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SDLRC - Scientific Articles all years by Author - M-Maq


The Sheahan Diamond Literature Reference Compilation
The Sheahan Diamond Literature Reference Compilation is compiled by Patricia Sheahan who publishes on a monthly basis a list of new scientific articles related to diamonds as well as media coverage and corporate announcementscalled the Sheahan Diamond Literature Service that is distributed as a free pdf to a list of followers. Pat has kindly agreed to allow her work to be made available as an online digital resource at Kaiser Research Online so that a broader community interested in diamonds and related geology can benefit. The references are for personal use information purposes only; when available a link is provided to an online location where the full article can be accessed or purchased directly. Reproduction of this compilation in part or in whole without permission from the Sheahan Diamond Literature Service is strictly prohibited. Return to Diamond Resource Center
Sheahan Diamond Literature Reference Compilation - Scientific Articles by Author for all years
A-An Ao+ B-Bd Be-Bk Bl-Bq Br+ C-Cg Ch-Ck Cl+ D-Dd De-Dn Do+ E F-Fn Fo+ G-Gh Gi-Gq Gr+ H-Hd He-Hn Ho+ I J K-Kg Kh-Kn Ko-Kq Kr+ L-Lh
Li+ M-Maq Mar-Mc Md-Mn Mo+ N O P-Pd Pe-Pn Po+ Q R-Rh Ri-Rn Ro+ S-Sd Se-Sh Si-Sm Sn-Ss St+ T-Th Ti+ U V W-Wg Wh+ X Y Z
Sheahan Diamond Literature Reference Compilation - Media/Corporate References by Name for all years
A B C D-Diam Diamonds Diamr+ E F G H I J K L M N O P Q R S T U V W X Y Z
Tips for Users
Posted/Published Reference CodesThe SDLRC provides 3 types of references identified in the reference code. DS for scientific article, DM for a media article, and DC for a corporate announcement. Consider DS0512-0001. The DS stands for "diamond scientific". 05 stands for 2005, the year the reference was posted. 12 represents the month the reference was posted. For all years prior to 2015 the default month is 12. -0001 is the reference's identifier and it does not mean anything. The number below the refence code, ie 2015, is the year the article was published. Note that the posted year may sometimes be later than the published year.
Sort OrderReferences are sorted by the "author" name and when the reference was posted to the compilation.
Most RecentIf the reference code is highlighted yellow, the reference was made available through the most recent monthly compilation of new literature. Use this to check out new references. When new references are posted, we make it our priority to track down an online link and obtain an abstract. With regard to older references, tracking down an abstract and an online link is a work in progress.
Link to external location of article: If the title has a link, it means we have found a location online where you can either retrieve the full article free, or purchase access to it. The Sheahan Diamond Literature Service is not a technical article procurement service; if you want a restricted article, you must deal directly with the vendor who controls the copyright to the article.
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Author Index
A-An Ao+ B-Bd Be-Bk Bl-Bq Br+ C-Cg Ch-Ck Cl+ D-Dd De-Dn Do+ E F-Fn Fo+ G-Gh Gi-Gq Gr+ H-Hd He-Hn Ho+ I J K-Kg Kh-Kn Ko-Kq Kr+ L-Lh
Li+ M-Maq Mar-Mc Md-Mn Mo+ N O P-Pd Pe-Pn Po+ Q R-Rh Ri-Rn Ro+ S-Sd Se-Sh Si-Sm Sn-Ss St+ T-Th Ti+ U V W-Wg Wh+ X Y Z
Sheahan Diamond Literature Reference Compilation - Scientific Articles by Author for all years - M-Maq
Posted/
Published
AuthorTitleSourceRegionKeywords
DS201906-1298
2019
MGuzmics, T., Berkesi, M, Bodnar, R.J., Fall, A., Bali, E., Milke, R., Vetlenyi, E., Szabo, C.Natrocarbonatites: a hidden product of three phase immiscibility.Geology, Vol. 47, 6, pp. 527-530.Africa, Tanzaniadeposit - Oldoinyo Lengai

Abstract: Earth’s only active natrocarbonatite volcanism, occurring at Oldoinyo Lengai (OL), Tanzania, suggests that natrocarbonatite melts are formed through a unique geological process. In the East African Rift, the extinct Kerimasi (KER) volcano is a neighbor of OL and also contains nephelinites hosting melt and fluid inclusions that preserve the igneous processes associated with formation of natrocarbonatite melts. Here, we present evidence for the presence of coexisting nephelinite melt, fluorine-rich carbonate melt, and alkali carbonate fluid. The compositions of these phases differ from the composition of OL natrocarbonatites; therefore, it is unlikely that natrocarbonatites formed directly from one of these phases. Instead, mixing of the outgassing alkali carbonate fluid and the fluorine-rich carbonate melt can yield natrocarbonatite compositions at temperatures close to subsolidus temperatures of nephelinite (<630-650 °C). Moreover, the high halogen content (6-16 wt%) in the carbonate melt precludes saturation of calcite (i.e., formation of calciocarbonatite) and maintains the carbonate melt in the liquid state with 28-41 wt% CaO at temperatures ?600 °C. Our study suggests that alkali carbonate fluids and melts could have commonly formed in the geological past, but it is unlikely they precipitated calcite that facilitates fossilization. Instead, alkali carbonates likely precipitated that were not preserved in the fossil nephelinite rocks. Thus, alkali carbonate fluids and melts have been so far overlooked in the geological record because of the lack of previous detailed inclusion studies.
DS201908-1806
2019
M, E.A.Ramiz, M.M., Mondal, M,E.A., Farooq, S.H.Geochemistry of ultramafic-mafic rocks of the Madawara ultramafic complex in the southern part of the Bundelkhand craton, Central Indian Shield: implications for mantle sources and geodynamic setting.Geological Journal, Vol. 54, 4, pp. 2185-2207.Indiacraton

Abstract: Detailed field, petrography and whole?rock geochemical study was carried out in order to constrain the mantle sources and geodynamic setting of the Madawara Ultramafic Complex (MUC) of the Bundelkhand Craton. Studies reveal that there are two types of ultramafic rocks: (a) high?Mg ultrabasic/basic rocks and (b) undeformed ultramafic-mafic plutonic rocks. The high?Mg ultrabasic/basic rocks have undergone severe low?grade (greenschist) metamorphism and are characterized by stringer and veinlet structures of talc-tremolite-actinolite schists with alternate layers of serpentinites showing comparatively higher SiO2 (46.1-49.4 wt%), lower MgO (24.6-26.2 wt%), and higher Al2O3 (4.58-7.06 wt%) and CaO (2.72-6.77 wt%) compared to the undeformed ultramafic rocks. The undeformed ultramafic rocks (mainly harzburgite, lherzolite, and olivine websterite) are characterized by globular structures and have lower SiO2 (40-44.1 wt%), higher MgO (30.4-38 wt%) and lower Al2O3 (1.84-4.03 wt%) and CaO (0.16-3.14 wt%). The undeformed mafic rocks (mainly gabbro) occur as small pockets within the undeformed ultramafic rocks as well as independent outcrops. Limited variation in Nb/Th against Nb/Yb along with negative Nb?Ti anomalies of all the rock types in the multi?element diagram reveals the significant role of the metasomatized mantle in their genesis. All the rocks show enrichment in light rare earth element and large?ion lithophile elements compared to heavy rare earth elements and high?field strength elements. The geochemical characteristics coupled with Ce/Yb versus Ce variation of the rocks of MUC point towards two different sources for their genesis. The high?Mg ultrabasic/basic rocks are derived from partial melting of metasomatized mantle at shallow depth, while the undeformed ultramafic rocks were formed as a result of asthenospheric upwelling from a greater depth that induced the melting in the overlying lithosphere. Gabbro rocks represent the last and most evolved phase of the complex. Geochemical signatures suggest that the rocks of MUC were formed in a continental arc setting.
DS202204-0540
2022
M, Y.Van Rythoven, A.D., Schulze, D.J., Stern, R.A., Lai, M, Y.Composition of diamond from the 95-2 pipe, Lake Timiskaming kimberlite cluster, Superior craton, Canada.The Canadian Mineralogist, Vol. 60, pp. 67-90. pdfCanada, Ontariocathodluminenescence

Abstract: Forty-one samples of diamond from the Jurassic 95-2 kimberlite pipe in the Lake Timiskaming Kimberlite Cluster, Superior Craton, Canada, were imaged using cathodoluminescence and analyzed by secondary ion mass spectrometry and Fourier-transform infrared absorbance spectrometry to determine carbon stable isotope composition, total nitrogen abundance, and nitrogen aggregation state. The carbon isotope compositions results (?13CVPDB) range from -9.11 to -3.57‰, with a mean value of -5.8‰. Intra-stone variation is small (maximum ?2.2‰, and in most individual diamond samples <1‰). Nitrogen contents range from 0.5 to 2040 ppm (mean of 483 ppm). The greatest range of values in a single stone is 825 ppm. The samples are poorly aggregated in terms of nitrogen. The samples are mostly type IaA or IaAB, with a few bordering on type Ib. Diamond growth was episodic, with nitrogen behaving highly compatibly (i.e., D = [N]diamond/[N]fluid >> 1). Precipitation was likely from a carbonate-rich fluid in a peridotitic (lherzolitic) environment within the mantle of the central Superior Craton. This generation of diamond growth is very similar to those reported from the Jurassic age Victor and U2 pipes of the Attawapiskat Kimberlite Cluster, and distinct from a possibly much older (>1.1 Ga) generation of diamond reported in other older host rocks (T1, Wawa, Lynx, and Renard). This older generation of diamond at these other localities is also predominantly of the peridotitic (harzburgitic) paragenesis but contains far less nitrogen (although typically more aggregated as B centers) and has higher ?13CVPDB. The younger generation of diamond formed after mantle heating during formation of the Mid-Continental Rift (ca. 1.1 Ga) destroyed any proximal prior generation(s) of diamond. Igneous activity after 1.1 Ga subsequently refertilized the cratonic mantle to a lherzolitic paragenesis in which the younger generation precipitated.
DS202103-0370
2021
m Couper, S.Brennan, M.C., Fischer, R.A,m Couper, S., Miyagi, L., Antonangeli, D., Morard, G.High-pressure deformation of iron-nickel-silicon alloys and implications for Earth's inner core.Journal of Geophysical Research, Solid Earth, https://eartharxiv.org /repository/ view/1694/ 21p. PdfMantleGeophysics - seismics

Abstract: The inner core is a Moon?sized ball of solid metal at the very center of the Earth. Vibrations from earthquakes move faster through the inner core if they travel parallel to Earth's axis (the line between the North and South Poles) than if they travel parallel to the Equator. This probably means that the grains of metal in the inner core are themselves aligned with Earth's axis. Previous studies determined that this alignment likely happened after the inner core had formed, but those experiments were done on pure iron, whereas the inner core is mostly iron but also contains other elements. We did experiments at high pressures and temperatures on a more realistic core metal containing iron, nickel, and silicon. We found that this metal would be much stronger than pure iron at inner core pressures and temperatures; it is still possible for it to produce a north-south alignment, but it is much more difficult for it to do so. This could mean that the alignment occurred while the inner core was forming (rather than afterward), which might change how we think about the forces present in the deep Earth today.
DS201904-0804
2017
m Gu, Y-C.Zhou, Z., Wang, G., Di, Y-J,m Gu, Y-C., Zhang, D., Zhu, W-p., Liu, C., Wu, C., Li, H., Chen, L.-z.Discovery of Mesoproterozoic kimberlite from Dorbed Benner, Inner Mongolia and its tectonic significance.Geochemistry International, doi:10.1002/gi.2939 14p.China, Mongoliadeposit - Longtou Shan

Abstract: Porphyritic olivine kimberlitic breccia, discovered in the Dörbed Banner of Inner Mongolia, Western China, is referred to as Longtou Shan Kimberlite in our study. This kimberlite occurs as a pipe in the Halahuogete Formation of Bayan Obo Group. Zircon U-Pb ages of Longtou Shan Kimberlite reveals a Mesoproterozoic age of ~1,552 Ma, constraining the deposition age of Halahuogete Formation to the Mesoproterozoic. Compared with Mesoproterozoic kimberlite of the ancient landmass, it can be inferred that the North China Craton is a member of the Ur ancient continent of the Columbia supercontinent. Furthermore, according to the tectonic background of the Bayan Obo Group, we raise this possibility that “Bayan Obo Aulacogen” should be renamed the “Bayan Obo Continental Rift.”
DS201905-1059
2019
m Hubik, P.Mortet, V., Vickova Zicova, Z., Taylor, A., Davydova, M., Frank, O,m Hubik, P., Lorincik, J., Aleshin, M.Determination of atomic boron concentration in heavily boron-doped diamond by Raman spectroscopy.Diamond & Related Materials, Vol. 93, pp. 54-58.Globalspectroscopy

Abstract: Raman spectroscopy has been foreseen as a simple and non-destructive characterization method to determine the boron concentration in heavily boron-doped diamond with metallic conductivity. However, currently available empirical studies are not fully satisfactory for enabling accurate determination of the boron concentration in diamond. Here, we study Raman spectra of epitaxial boron-doped diamond as a function of the boron concentration and the excitation wavelength. The zone center phonon and the phonon density of state maximum (at ca. 1200?cm?1) lines are analyzed using a decoupled double Fano-function. This analysis method accurately describes the observed variation of the asymmetric parameters with atomic boron concentration and the photon excitation energy and enables the determination of the atomic boron concentration from the parameters of the examined Raman lines.
DS201907-1532
2019
m Jiang, S-Y.Chen, W., Liu, H-Y,m Jiang, S-Y., Simonetti, A., Xu, C., Zhang, W.The formation of the ore-bearing dolomite marble from the giant Bayan Obo REE-Nb-Fe deposit, Inner Mongolia: insights from micron-scale geochemical data.Mineralium Deposita, in press available, 16p.Asia, Mongoliadeposit - Bayan Obo

Abstract: The genesis of Earth’s largest rare earth element (REE) deposit, Bayan Obo (China), has been intensely debated, in particular whether the host dolomite marble is of sedimentary or igneous origin. The protracted (Mesoproterozoic to Paleozoic) and intricate (magmatic to metasomatic) geological processes complicate geochemical interpretations. In this study, we present a comprehensive petrographic and in situ, high-spatial resolution Sr-Pb isotopic and geochemical investigation of the host dolomite from the Bayan Obo marble. Based on petrographic evidence, the dolomite marble is divided into three facies including coarse-grained (CM), fine-grained (FM), and heterogeneous marble (HM). All carbonates are ferroan dolomite with high SrO and MnO contents (>?0.15 wt.%), consistent with an igneous origin. Trace element compositions of these dolomites are highly variable both among and within individual samples, with CM dolomite displaying the strongest LREE enrichment. In situ 206Pb/204Pb and 207Pb/204Pb ratios of the dolomite are generally consistent with mantle values. However, initial 208Pb/204Pb ratios define a large range from 35.45 to 39.75, which may result from the incorporation of radiogenic Pb released from decomposition of monazite and/or bastnäsite during Early Paleozoic metasomatism. Moreover, in situ Sr isotope compositions of dolomite indicate a large range (87Sr/86Sr?=?0.70292-0.71363). CM dolomite is characterized by a relatively consistent, unradiogenic Sr isotope composition (87Sr/86Sr?=?0.70295-0.70314), which is typical for Mesoproterozoic mantle. The variation of 87Sr/86Sr ratios together with radiogenic 206Pb/204Pb signatures for dolomite within FM and HM possibly represents recrystallization during Early Paleozoic metasomatism with the contribution of radiogenic Sr and Pb from surrounding host rocks. Therefore, our in situ geochemical data support a Mesoproterozoic igneous origin for the ore-bearing dolomite marble in the Bayan Obo deposit, which subsequently underwent intensive metasomatism during the Early Paleozoic.
DS202003-0348
2020
m Kong, T.Lee, C.W.Y., Cheng, J., Yium Y.C., Chan, K., Lau, D., Tang, W.C., Cheng, K.W,m Kong, T., Hui, T.K.C., Jelezko, F.Correlation between EPR spectra and coloration of natural diamonds.Diamond & Related Materials, Vol. 103, 13p. PdfGlobaldiamond colour

Abstract: White diamonds color grading is one of the basic diamond evaluations. The color value based on a scale that ranges from D to Z, with D being the more colorless and more valuable, among other qualifications. As the diamond grade moves on this scale, its color appears more yellow progressively. This yellowish color, present only in Type I diamonds, is mainly due to the nitrogen related defects such as N3 center and C-center. The current color grading system is based on a visual method, where gemologist compares the sample with a Master Color set. However, this method is very subjective. Several defects responsible for light absorption in diamond are carrying electron spin and appear in Electron Paramagnetic Resonance (EPR) spectrum. In this study, we developed a new EPR based technique for a quantitative measurement of N3 center and C-center in diamond through quantitative EPR spectroscopy. The correlation between EPR spectra and color grades of diamond was established.
DS202007-1178
2020
m Phillips, D.Soltys, A., Giuliani, A,m Phillips, D., Kamenetsky, V.S.Kimberlite metasomatism of the lithosphere and the evolution of olivine in carbonate rich melts evidence from the Kimberley kimberlites ( South Africa).Journal of Petrology, 10.1093/petrology /egaa062/5857610 90p. PdfAfrica, South Africadeposit - Kimberley

Abstract: Olivine is the most abundant phase in kimberlites and is stable throughout most of the crystallisation sequence, thus providing an extensive record of kimberlite petrogenesis. To better constrain the composition, evolution, and source of kimberlites we present a detailed petrographic and geochemical study of olivine from multiple dyke, sill, and root zone kimberlites in the Kimberley cluster (South Africa). Olivine grains in these kimberlites are zoned, with a central core, a rim overgrowth, and occasionally an external rind. Additional ‘internal’ and ‘transitional’ zones may occur between the core and rim, and some samples of root zone kimberlites contain a late generation of high-Mg olivine in cross-cutting veins. Olivine records widespread pre-ascent (proto-)kimberlite metasomatism in the mantle including: (a) Relatively Fe-rich (Mg# <89) olivine cores interpreted to derive from the disaggregation of kimberlite-related megacrysts (20% of cores); (b) Mg-Ca-rich olivine cores (Mg# >89; >0.05?wt.% CaO) suggested to be sourced from neoblasts in sheared peridotites (25% of cores); (c) transitional zones between cores and rims probably formed by partial re-equilibration of xenocrysts (now cores) with a previous pulse of kimberlite melt (i.e., compositionally heterogeneous xenocrysts); and (d) olivine from the Wesselton water tunnel sills, internal zones (I), and low-Mg# rims, that crystallised from a kimberlite melt that underwent olivine fractionation within the shallow lithospheric mantle. Magmatic crystallisation begins with internal olivine zones (II), which are common but not ubiquitous in the Kimberley olivine. These zones are euhedral, contain rare inclusions of chromite, and have a higher Mg# (90.0 ± 0.5), NiO, and Cr2O3 contents, but are depleted in CaO compared to the rims. Internal olivine zones (II) are interpreted to crystallise from a primitive kimberlite melt during its ascent and transport of olivine toward the surface. Their compositions suggest assimilation of peridotitic material (particularly orthopyroxene) and potentially sulfides prior to or during crystallisation. Comparison of internal zones (II) with liquidus olivine from other mantle-derived carbonate-bearing magmas (i.e., orangeites, ultramafic lamprophyres, melilitites) show that low (100×) Mn/Fe (?1.2), very low Ca/Fe (?0.6), and moderate Ni/Mg ratios (?1.1) appear to be the hallmarks of olivine in melts derived from carbonate-bearing garnet-peridotite sources. Olivine rims display features indicative of magmatic crystallisation, which are typical of olivine rims in kimberlites worldwide - i.e. primary inclusions of chromite, Mg-ilmenite and rutile, homogeneous Mg# (88.8 ± 0.3), decreasing Ni and Cr, increasing Ca and Mn. Rinds and high-Mg olivine are characterised by extreme Mg-Ca-Mn enrichment and Ni depletion, and textural relationships indicate these zones represent replacement of pre-existing olivine, with some new crystallisation of rinds. These zones likely precipitated from evolved, oxidised, and relatively low-temperature kimberlite fluids after crustal emplacement. In summary, this study demonstrates the utility of combined petrography and olivine geochemistry to trace the evolution of kimberlite magmatic systems from early metasomatism of the lithospheric mantle by (proto-)kimberlite melts, to crystallisation at different depths en route to surface, and finally late-stage deuteric/hydrothermal fluid alteration processes after crustal emplacement.
DS202104-0580
2019
m Seitz, H-M.Grass, C., Woodland, A., Hoferm H,m Seitz, H-M., Pearson, G., Kjarsgaard, B.Metasomatism and oxidation state of the lithospheric mantle beneath the Rae Craton, Canada as revealed by xenoliths from Somerset Island and Pelly Bay. ***note dateGeophysical Research abstracts, EGU, EGU2019-9348, 1p. PdfCanadageodynamics

Abstract: We present the first oxidation state measurements for the subcontinental lithospheric mantle (SCLM) beneath the Rae craton, northern Canada, one of the largest components of the Canadian shield. In combination with major and trace element compositions for garnet and clinopyroxene, we assess the relationship between oxidation state and metasomatic overprinting. The sample suite comprises peridotite xenoliths from the central part (Pelly Bay) and the craton margin (Somerset Island) providing insights into lateral and vertical variations in lithospheric character. Our suite contains spinel, garnet-spinel and garnet peridotites, with most samples originating from 100 to 140 km depth. Within this narrow depth range we observe strong chemical gradients, including variations in oxygen fugacity (ƒO2) of over 4 log units. Both Pelly Bay and Somerset Island peridotites reveal a change in metasomatic type with depth. Observed geochemical systematics and textural evidence support the notion that Rae SCLM developed through amalgamation of different local domains, establishing chemical gradients from the start. These gradients were subsequently modified by migrating melts that drove further development of different types of metasomatic overprinting and variable oxidation at a range of length scales. This oxidation already apparent at ~?100 km depth could have locally destabilised any pre-existing diamond or graphite.
DS202010-1845
2020
m Simakin, A.Gordeychik, B., Churikova, T., Shea, T., Kronz, A,m Simakin, A., Worner, G.Fo and Ni relations in olivine differentiate between crystallization and diffusion trends.Journal of Petrology, 10.1093/petrology/egaa083Mantleolivine

Abstract: Nickel is a strongly compatible element in olivine, and thus fractional crystallization of olivine typically results in a concave-up trend on a Fo-Ni diagram. "Ni-enriched" olivine compositions are considered those that fall above such a crystallization trend. To explain Ni-enriched olivine crystals, we develop a set of theoretical and computational models to describe how primitive olivine phenocrysts from a parent (high-Mg, high-Ni) basalt re-equilibrate with an evolved (low-Mg, low-Ni) melt through diffusion. These models describe the progressive loss of Fo and Ni in olivine cores during protracted diffusion for various crystal shapes and different relative diffusivities for Ni and Fe-Mg. In the case when the diffusivity of Ni is lower than that for Fe-Mg interdiffusion, then olivine phenocrysts affected by protracted diffusion form a concave-down trend that contrasts with the concave-up crystallization trend. Models for different simple geometries show that the concavity of the diffusion trend does not depend on the size of the crystals and only weakly depends on their shape. We also find that the effect of diffusion anisotropy on trend concavity is in the same magnitude as the effect of crystal shape. Thus, both diffusion anisotropy and crystal shape do not significantly change the concave-down diffusion trend. Three-dimensional numerical diffusion models using a range of more complex, realistic olivine morphologies with anisotropy corroborate this conclusion. Thus, the curvature of the concave-down diffusion trend is mainly determined by the ratio of Ni and Fe-Mg diffusion coefficients. The initial and final points of the diffusion trend are in turn determined by the compositional contrast between mafic and more evolved melts that have mixed to cause disequilibrium between olivine cores and surrounding melt. We present several examples of measurements on olivine from arc basalts from Kamchatka, and several published olivine datasets from mafic magmas from non-subduction settings (lamproites and kimberlites) that are consistent with diffusion-controlled Fo-Ni behaviour. In each case the ratio of Ni and Fe-Mg diffusion coefficients is indicated to be?
DS202205-0730
2021
m Yurimoto, H.Wang, W., Sueno, S,m Yurimoto, H., Takahashi, E.Geochemical study of eclogitic mineral inclusions from Chinese diamonds.Researchgate Chapter, 8p. PdfChinadiamond inclusions

Abstract: Major and trace element geochemistry of eclogitic mineral inclusions from Chinese diamonds are reported in this study, for the first time. Bulk major element compositions of mantle eclogite, estimated from diamond inclusions, are very close to that of MORB. All the analyzed samples exhibit evident positive Eu anomalies. Estimated bulk trace element compositions of mantle eclogite are generally parallel to that of MORB, but with deviations like enrichment in LILE and depletion in HFSE. It is proposed that the formation of mantle eclogite could be closely related to recycling of ancient oceanic crust. Other processes like (1) metasomatism by incompatible trace element rich melts; or (2) remelting and interaction with mantle peridotite, may also be involved. Coexisting of olivine with eclogitic mineral inclusions in a same diamond host, and evident trace element variations in some mineral inclusions show that some diamonds were formed by disequilibrium growth.
DS202004-0545
2020
M.Wright, L.J., M., Muirhead, J.D., Scholz, C.ASpatio-temporal variations in upper crustal extension across the different basement terranes of the Lake Tanganyika Rift, East Africa.Tectonics, Vol. 39, 3, doi:e2019TC006019Africacraton

Abstract: Preexisting crustal heterogeneities are shown to influence rift process at a variety of scales. However, our understanding of how crustal inheritance influences rift?scale spatiotemporal kinematics of faulting in magma?poor rift environments is still very limited. Studies of active continental rifts can provide high?fidelity assessments of extensional processes and structures that are not possible through examination of ancient rifts that have undergone subsequent deformation events or are buried deeply beneath passive margins. We examine the influence of crustal inheritance on active rifting through balancing and restoring a series of regional cross sections across the Lake Tanganyika Rift in the Western Branch of the East African Rift System. The cross sections are produced using legacy seismic reflection data, reprocessed through prestack depth migration. This type example of a young, magma?poor continental rift transects several different basement terranes, including an Archean/Paleoproterozoic craton, and Proterozoic mobile belts. The Lake Tanganyika Rift exhibits two classic bell?shaped profiles of extension along strike, reaching a maximum of 7.15 km. A spatiotemporal integration of the extension data, and comparison with the various basement terranes the rift transects, reveals that extension in cratonic blocks is more widely distributed compared to mobile belt terranes, where strain rapidly localizes onto border faults by later rift stages. These results reveal how crustal inheritance exerts a fundamental control on the evolution of extension localization, ultimately impacting the geometry and structural architecture of rift basins.
DS202106-0922
2021
M.Ashchepkov, I.,Medvedev, N.,Ivanov, A., Vladykin, N., Ntafos,T.,Downes, H.,Saprykin, A.,Tolstov, A.Vavilov, M., Shmarov, G.Deep mantle roots of the Zarnitsa kimberlite pipe, Siberian craton, Russia: evidence for multistage polybaric interaction with mantle melts.Journal of Asian Earth Sciences, Vol. 213, 104756, 22p.pdfRussia, Siberiadeposit - Zarnitsa

Abstract: Zarnitsa kimberlite pipe in Central Yakutia contains pyrope garnets with Cr2O3 ranging from 9 to 19.3 wt% derived from the asthenospheric mantle. They show mostly S-shaped, inflected rare earth element (REE) patterns for dunitic and harzburgitic, lherzolitic and harzburgitic varieties and all are rich in high field strength elements (HFSE) due to reaction with protokimberlite melts. Lithospheric garnets (<9 wt% Cr2O3) show a similar division into four groups but have more symmetric trace element patterns. Cr-diopsides suggest reactions with hydrous alkaline, protokimberlitic and primary (hydrous) partial melts. Cr-diopsides of metasomatic origin have inclined REE patterns and high LILE, U, Th and Zr concentrations. Four groups in REE of Ti-rich Cr-diopsides, and augites have asymmetric bell-like REE patterns and are HFSE-rich. Mg-ilmenites low in REE were formed within dunite conduits. Ilmenite derived from differentiated melts have inclined REE patterns with LREE ~ 100 × chondrite levels. Thermobarometry for dunites shows a 34 mWm?2 geotherm with a HT branch (>50 mWm?2) at 6-9 GPa, and a stepped HT geotherm with heated pyroxenite lenses at four levels from 6.5 to 3.5 GPa. Parental melts calculated with KDs suggest that augites and high-Cr garnets in the lithosphere base reacted with essentially carbonatitic melts while garnets from lower pressure show subduction peaks in U, Ba and Pb. The roots of the Zarnitsa pipe served to transfer large portions of deep (>9 GPa) protokimberlite melts to the lithosphere. Smaller diamonds were dissolved due to the elevated oxidation state but in peripheral zones large diamonds could grow.
DS202106-0960
2021
M.Mohammed, A. Al Deep, M.Depth to the bottom of the magnetic layer, crustal thickness, and heat flow in Africa: inferences from gravity and magnetic data.Journal of African Earth Sciences, Vol. 179, 104204, 17p. PdfAfricaEMAG2

Abstract: Data from the Earth Gravitational Model (EGM2008) and the Earth Magnetic Anomaly Grid (EMAG2) were used to develop a continental scale crustal thickness model for Africa, and to estimate the depth to the bottom of the magnetic layer (DBML) and the geothermal gradient and heat flow. The results are: (1) the estimated DBML from the magnetic data varies from ~23.0 to ~37.2 km. The shallowest DBML values are located in the northern, eastern, and western parts of the continent, whereas the deepest values are observed in the central and southern regions. (2) The estimated crustal thickness based on gravity data varies from ~29.9 km in the northern and western parts of Africa to ~48.0 km in its southern regions, with an average thickness of 35.1 km for the whole continent. (3) The estimated heat flow varies between high values of 46-59 mW/m2, observed in the northern, eastern, and western regions to low values of ~< 41 mW/m2, observed in the central and southern parts of the continent. (4) The geothermal gradient values vary between 14.5 and 23.6 °C/km (5) The East African rift zone is underlain by shallow DBML characterized by high heat flow values that vary between 42 and 59 mW/m2 (6) The heat flow anomalies in Egypt and Libya may be associated with the zone of the Pelusium megashear system, and it shows heat flow values that vary between 36.3 and 59.0 mW/m2. The current study has taken advantage of the availability of the EGM2008 and EMAG2 datasets to map crustal thickness variations and DBML beneath the continental landmass of Africa.
DS202109-1490
2021
M.C.J.Spaggiari, R.I. de Wit, M.C.J.Diamondiferous alluvial deposits of the Longatshimo Valley, Kasai Province, southern DRC: a sedimentary and economic model of a central African diamond placer.South African Journal of Geology, Vol. 124, pp. 499-518.Africa, Democratic Republic of Congodeposit - Kasai

Abstract: The Kasai alluvial field in southern Democratic Republic of Congo (DRC) is part of central Africa’s largest diamond placer that has produced more than 200 million carats, mainly derived from Quaternary deposits. A small part of these deposits, along and within the Longatshimo River, is the subject of this study providing a glimpse into the alluvial history of the Kasai diamond placer. This work documents their sedimentological and diamond mineralization attributes, as well as their emplacement processes, which can inform future exploration models. The key controls of this placer formation, notably Quaternary climatic variations, fluvial landscape evolution and bedrock conditions are also evaluated. A consequence of the interplay among these processes is that diamond supply (from Cretaceous alluvial sources), recycling and concentration were most pronounced and consistent, in the Late Quaternary. Alluvial diamond mineralization in this central African region thus evolved differently to those in southern Africa. Based on exploration results in the Longatshimo Valley, diamond concentration improves but diamond size diminishes with decreasing deposit age, and thus the modern river sediments contain the highest abundance but smallest diamonds. This is opposite to the grade and diamond size trend that characterises southern African fluvial diamond placers. The Longatshimo River study offers insight into the Kasai alluvial field, and its placer model is expected to be applicable to the exploration of other central African diamond placers.
DS1860-0249
1875
M.E.M.E.Life on the Diamond Fields KimberleyLondon: Wertheimer., 54P.Africa, South Africa, Griqualand WestBiography
DS202111-1778
2021
M.I.Nadolinny, V.A., Komarovskikh, A.Yu., Rakhmanova, M.I.,Yuryeva, O.P., Shatsky, V.S., Palyanov, Yu.N. Guskova, M.I.New data on the N1 nitrogen paramagnetic center in brownish type IaAB diamonds from Mir pipe.Diamond and Related Materials, Vol. 120, 108638 6p. PdfRussiadeposit - Mir

Abstract: In this work, two brownish crystals from the Mir pipe attributed to type IaAB have been examined by a complex of spectroscopic methods: electron paramagnetic resonance, infrared, and photoluminescence spectroscopies. A combination of features such as brownish color, optical system 490.7 nm, and paramagnetic centers W7 and 490.7 points out to plastic deformation of the crystals. The W7 is known to be formed as a result of destruction of A-aggregates during plastic deformation while part of the N3V centrers can be formed due to the disruption of the B-aggregates. The narrow-line EPR spectra from the nitrogen-related N3V centers and the P1 centers indicate that the crystals were annealed after plastic deformation. Another feature of the crystals studied is the observation of the well-known paramagnetic N1 center with only two magnetically inequivalent positions (i.e. with two magnetically inequivalent directions of the C1-N1 fragments) instead of the previously reported four. Possible transformation pathways of the W7 center (N1-C1-C2-N2+) into the N1 center (N1-C-N2+) during the post-deformation annealing are considered.
DS1859-0094
1848
M.M.F.M.M.F.Scripture, Natural History, Being an Account of Animals, Trees, Plants and Precious Stones.London: Soc. For Promoting Christian Knowledge Royal Exchang, 2ND. EDITION, 452P.GlobalTravelogue
DS200912-0861
2009
MaZheng, J.P., Griffin, W.L., O'Reilly, S.Y., Zhao, J.H., Wu, Liu, Pearson, Zhang, Ma, Zhang, Yu, Su, TangNeoarchean ( 2.7-2.8 Ga) accretion beneath the North Chin a Craton: U Pb age, trace elements and Hf isotopes of zircons in Diamondiferous kimberlites.Lithos, Vol. 117, pp. 188-202.ChinaGeochronology
DS201012-0765
2010
MaSu, B-X., Zhang, H-F., Sakyi, P.A., Yang, Y-H., Ying, J-F., Tang, Y-J., Qin, K-Z., Xiao, Y., Zhao, Mao, MaThe origin of spongy texture in minerals of mantle xenoliths from the western Qinling, central China.Contributions to Mineralogy and Petrology, in press available, 18p.ChinaXenoliths
DS2000-0601
2000
Ma, C.Ma, C., Ehlers, C., et al.The roots of the Dabie Shan ultrahigh pressure metamorphic terrane: constraints from geochemistry NdSrPrec. Research, Vol. 102, No. 3-4, Aug. pp. 303-Chinaultra high pressure (UHP), Dabie Shan
DS2000-0602
2000
Ma, C.Ma, C., Ehlers, C., Xu, C., Li, Z., Yang, K.The roots of the Dabie Shan ultrahigh pressure metamorphic terrane: constraints from geochemistry ...Precambrian Research, Vol. 102, No. 3-4, Aug.pp. 279-301.Chinaultra high pressure (UHP), geochronology, Dabie Shan region
DS200512-0664
2005
Ma, C.Ma, C., She, Z., Ai, X.An Early Cretaceous intrusive complex in the Dabie Shan ultrahigh pressure metamorphic terrane, East China. Evidence for the beginning of post orogenic collapse.GAC Annual Meeting Halifax May 15-19, Abstract 1p.ChinaUHP, crustal root
DS201710-2279
2017
Ma, C.Wu, W., Yang, J., Ma, C., Milushi, I., Lian, D., Tian, Y.Discovery and significance of diamonds and moissanites in chromitites within the Skenderbeu Massif of the Mirdita zone ophiolite, west Albania.Acta Geologica Sinica, Vol. 91, 3, pp. 882-897.Europe, Albaniamoissanites

Abstract: In recent years diamonds and other unusual minerals (carbides, nitrides, metal alloys and native elements) have been recovered from mantle peridotites and chromitites (both high-Cr chromitites and high-Al chromitites) from a number of ophiolites of different ages and tectonic settings. Here we report a similar assemblage of minerals from the Skenderbeu massif of the Mirdita zone ophiolite, west Albania. So far, more than 20 grains of microdiamonds and 30 grains of moissanites (SiC) have been separated from the podiform chromitite. The diamonds are mostly light yellow, transparent, euhedral crystals, 200-300 ?m across, with a range of morphologies; some are octahedral and cuboctahedron and others are elongate and irregular. Secondary electron images show that some grains have well-developed striations. All the diamond grains have been analyzed and yielded typical Raman spectra with a shift at ?1325 cm?1. The moissanite grains recovered from the Skenderbeu chromitites are mainly light blue to dark blue, but some are yellow to light yellow. All the analyzed grains have typical Raman spectra with shifts at 766 cm?1, 787 cm?1, and 967 cm?1. The energy spectrums of the moissanites confirm that the grains are composed entirely of silicon and carbon. This investigation expands the occurrence of diamonds and moissanites to Mesozoic ophiolites in the Neo-Tethys. Our new findings suggest that diamonds and moissanites are present, and probably ubiquitous in the oceanic mantle and can provide new perspectives and avenues for research on the origin of ophiolites and podiform chromitites.
DS201803-0472
2017
Ma, C.Rubin, A.E., Ma, C.Meteoritic minerals and their origins. Review Chemie der Erde, Vol. 77, pp. 325-385.Globalmeteorites

Abstract: About 435 mineral species have been identified in meteorites including native elements, metals and metallic alloys, carbides, nitrides and oxynitrides, phosphides, silicides, sulfides and hydroxysulfides, tellurides, arsenides and sulfarsenides, halides, oxides, hydroxides, carbonates, sulfates, molybdates, tungstates, phosphates and silico phosphates, oxalates, and silicates from all six structural groups. The minerals in meteorites can be categorized as having formed by a myriad of processes that are not all mutually distinct: (1) condensation in gaseous envelopes around evolved stars (presolar grains), (2) condensation in the solar nebula, (3) crystallization in CAI and AOI melts, (4) crystallization in chondrule melts, (5) exsolution during the cooling of CAIs, (6) exsolution during the cooling of chondrules and opaque assemblages, (7) annealing of amorphous material, (8) thermal metamorphism and exsolution, (9) aqueous alteration, hydrothermal alteration and metasomatism, (10) shock metamorphism, (11) condensation within impact plumes, (12) crystallization from melts in differentiated or partially differentiated bodies, (13) condensation from late-stage vapors in differentiated bodies, (14) exsolution, inversion and subsolidus redox effects within cooling igneous materials, (15) solar heating near perihelion, (16) atmospheric passage, and (17) terrestrial weathering.
DS201805-0984
2018
Ma, C.Tschauner, O., Huang, S., Greenberg, E., Prakapenka, V.B., Ma, C., Rossman, G.R., Shen, A.H., Zhang, D., Newville, M., Lanzirotti, A., Tait, K.Ice-VII inclusions in diamonds: evidence for aqueous fluid in the Earth's deep mantle. Orapa, ShandongScience, Vol. 359, pp. 1136-1139.Africa, South Africa, Botswana, Congo, Sierra Leone, Chinadiamond inclusions
DS201909-2105
2019
Ma, C-Q.Wang, L-X., Ma, C-Q., Salih, M-A., Abdallisamed, M-I-M., Zhu, Y-X.The syenite-carbonatite-fluorite association in Jebel Dumbier complex ( Sudan): magma origin and evolution.Goldschmidt2019, 1p. Poster abstractAfrica, Sudancarbonatite

Abstract: Jebel Dumbier is the first-identified carbonatite-bearing alkaline complex in Sudan. It is located on the northeastern margin of the Nuba Mountains in the south part of Sudan. The complex exposed as small elliptical hills with outcrops of around 8 km2. It is composed of dominant orthoclasite and ditroite and subdominant carbonatite and fluorite dykes. The fluorite dykes are mined and together with the carbonatite dykes are controlled by a NNE strike-slip fault system. Orthoclasite is the dominant rock type, comprising of orthoclase, kalsilite, few interstitial biotite and calcium carbonate and accesserary minerals of fluorite, apatite and zircon. Ditroite consists of perthite, aegirine-augite, nepheline, sodalite, and minor annite-phlogopite and richterite, with common accessories of fluorite, titanite, apatite and zircon. Zircon U-Pb dating reveals that both orthoclasite and ditroite emplaced at around 600 Ma. Relative to orthoclasites, ditroites display higher FeOtotal and MgO and lower Al2O3 contents, contain higher volatiles (F, Cl, Br, S), and are more depleted in LILEs (Rb, Sr, Ba) and enriched in HFSEs (Nb, Ta, Zr, Hf, Th, U) and REEs. Isotopic data imply that the ditoite, orthoclasite, fluorite and carbonatite dyke originated from a common source of depleted mantle affinities, with identical low initial 87Sr/86Sr ratios (0.7033-0.7037) and high ?Nd (t) values (1.6-2.7). The carbonatites display ?13C(V-PDB) of -5.8 to -6.7‰ and ?18O(SMOW) of 9.1 to 11.3‰, typical of primary igneous carbonatite worldwide. We propose that the orthoclasite, ditroite, carbonatite, and fluorite association in Jebel Dumbier is product of variable degrees of fractional crystallization of mantlederived volatile-rich magma. Magma immiscibility among silicates, carbonates and fluorates may proceed. The Jebel Dumbier alkaline-carbonatite complex represents the postorogenic alkaline magmatism during the end evolution of Pan-African orogen (650-550 Ma) at Arabian-Nubian Shield.
DS202110-1624
2021
Ma, C-Y.Long, Z-Y., Yu, X-Y., Jiang, X., Guo, B-J., Ma, C-Y., You, Y., Zheng, Y-Y.Fluid boiling and fluid-rock interaction as primary triggers for emerald deposition: insights from the Dayakou emerald deposit ( China).Ore Geology Reviews, Vol. 139, 104454, 15p. PdfChinaemerald

Abstract: The formation of tectonic magmatic-related emerald deposits necessarily invokes a mixing model of Be-rich granitic rocks and Cr and/or V-rich surrounding rocks. However, there has been continuing debate on the deposit genesis, with the essential controversy being the relative significance of magma versus metamorphism in mineralizing as well as the key triggers for emerald deposition. The Dayakou emerald deposit genetically related to the Cretaceous granitic magmatism and hosted within the Neoproterozoic metasedimentary rocks is an ideal study case to probe into the above outstanding issue. In this paper, three hydrothermal mineralization and related alteration stages have been recognized in Dayakou, comprised of the greisenization and early emerald mineralization in high-temperature hydrothermal condition (stage-I; peak at 380 °C to 480 °C), the silicification and main emerald mineralization in medium-high temperature fluid (stage-II; peak at 300 °C to 360 °C) and the late carbonate alteration and scheelite mineralization (stage-III). Analysis results of fluid inclusion and C-H-O isotopes of emeralds and associated minerals suggest that ore-forming fluids belong to the H2O-NaCl ± CO2 system with minor H2S, CH4, and N2, exsolved from the Cretaceous granites and gradually interacted with the surrounding metamorphic rocks. We combine the new data with those reported in earlier studies to further propose a genesis scenario for the Dayakou deposit, in which Be-bearing fluids originally exsolved from peraluminous melts and fluoride complexes may be an effective transport proxy for Be in hydrothermal fluids. Fluid boiling during fluid ascent leads to the significant fractionation and enrichment of elements and the escape of volatiles (e.g., HF, H2O, CO2) in ore system. Meanwhile, sustained fluid-rock interaction (e.g., greisenization) increasingly extracts Cr, V and Ca into fluids to facilitate mineral precipitation, wherein the crystallization of fluoride minerals would cause the destabilization of Be-F complexes. Our study indicates that fluid boiling and fluid-rock interactions are the primary triggers for emerald deposition.
DS201906-1305
2019
Ma, F.Kopylova, M., Tso, E., Ma, F., Liu, J., Pearson, D.G.From regional to local metasomatism in the peridotitic mantle of the Chidliak kimberlite province ( Southern Baffin Island).GAC/MAC annual Meeting, 1p. Abstract p. 124.Canada, Baffin Islanddeposit - Chidliak

Abstract: We studied the petrography, mineralogy, thermobarometry and whole rock chemistry of 120 peridotite and pyroxenite xenoliths collected from the 156 - 138 Ma Chidliak kimberlites CH-1, -6, -7 and -44. The xenoliths have higher CaO contents relative to Al2O3, and high Al for a given Mg/Si ratio compared to other cratonic peridotites. We assign the complex Ca-Al systematics of the Chidliak peridotites to repeated episodes of Ca-rich, Si-poor metasomatism, which introduced clinopyroxene and garnet, and later replaced orthopyroxene and clinopyroxene with secondary clinopyroxene and monticellite. This carbonatitic metasomatism, manifest in formation of wehrlites, acted upon the entire sampled mantle depth on a regional scale, including the proximal blocks of the North Atlantic Craton and the Chidliak mantle, where clinopyroxene and garnet modes are uniformly and heterogeneously high in the ~ 110 km deep mantle segment. Another, more recent type of mantle metasomatism, is expressed as elevated Ti in clinopyroxene and elevated Na and Ti in garnet, typical of sheared peridotites from CH-1, -7, and -44, but absent from CH-6 xenolith suite. The Ti-Na imprint is most intense in xenoliths derived from depths equivalent to 5.5 to 6.5 GPa, where it is associated with higher strain, the presence of sheared peridotites and higher temperatures varying isobarically by up to 200 °C. The horizontal scale of the thermal-metasomatic imprint is more ambiguous and could be as regional as 10's of kilometers or as local as < 1 km. The latter is constrained by the varied abundance of Ti-enriched garnets within a single kimberlite. The time-scale of this metasomatism relates to a conductive length-scale and could be as short as 100's ka, shortly predating the kimberlite formation. The Ti-Na, megacryst-like metasomatism may have resulted from a highly localized influx of hot hydrous proto-kimberlite fluids that weakened the mantle and triggered the formation of sheared peridotites.
DS200912-0864
2009
Ma, H.Zhou, S., Zang, C., Ma, H., Li, X., Zhang, H., Jia, X.Study on growth of coarse grains of diamond with high quality under HPHT.Chinese Science Bulletin, Vol. 54, 1, pp. 163-167.TechnologyUHP
DS201802-0225
2018
Ma, H.Chen, N., Ma, H., Chen, L., Yan, B., Fang, C., Liu, X., Li, Y., Guo, L., Chen, L., Jia, X.Effects of S on the synthesis of type 1b diamond under high pressure and high temperature.International Journal of Refractory Metals & Hard Materials, Vol. 71, pp. 141-146.Technologysynthetic diamonds
DS200512-1231
2005
Ma, H.A.Zang, C.Y., Jia, X.P., Ma, H.A., Tian, Y., Xiao, H.Y.Effect of regrown graphite on the growth of large gem diamonds by temperature gradient method.Chinese Physics Letters , Vol. 22, 9, pp. 2415-2417.TechnologyDiamond morphology
DS202110-1625
2021
Ma, H-a.Lu, Z., Zhao, H., Wang, Y., Fang, S., Cai, Z., Wang, Z., Ma, H-a., Chen, L., Jia, H., Jia, X.Diamond growth and characteristics in the metal-silicate-H2O-C system at HPHT conditions.Lithos, Vol. 404-405, 106470, 11p. PdfMantlediamond crystals

Abstract: The detailed phase composition and characteristics of diamond crystals grown in the metal-silicate-H2O-C system at 5.5 GPa and 1385 °C are reported in this paper. The conversion efficiency of the graphite-to-diamond in the metal-silicate-C system is lower than that in the metal-C system, which significantly decreases the growth rate of crystal. As the Mg2Si3O8•5H2O content increases to 1.5 wt%, growth pits and {110} related features of trigonal pyramids, skeletal structure, rhombic dodecahedron, and {110} dendrites exhibit in sequence. Simultaneously, the content of graphite and metal inclusions inside the crystal increases. These systematic changes are accompanied by the appearance of Csingle bondH, Csingle bondO, and Cdouble bondO bonds and a decrease of nitrogen content from ?210 ppm to ?60 ppm. It is speculated that H2O will further decompose and bond with carbon atoms and finally enter the diamond structure. The formation of Csingle bondH and Cdouble bondO bonds will terminate the extension of the three-dimensional network of Csingle bondC bonds. These defects will accumulate along the [111] direction and form {110} related characteristics. These chemical bonds also compete with the nitrogen in the system during entering into the diamond lattice. Our experimental model may provide implications for the morphology and formation environment of natural diamonds.
DS200712-1133
2007
Ma, J.Wang, Q., Wyman, D.A., Xu, J., Jian, P., Zhao, Z., Li, C., Xu, W., Ma, J., He, B.Early Cretaceous adakitic granites in the northern Dabie Complex, central China: implications for partial melting and delamination of thickened lower crust.Geochimica et Cosmochimica Acta, Vol. 71, 10, May 15, pp. 2609-2636.ChinaUHP - Dabie Shon
DS201112-0599
2011
Ma, J.Li, Z., Li, L., Zhang, R., Ma, J.An improved classification method for hyper spectral dat a based on spectral and morphological information.International Journal of Remote Sensing, Vol. 32, 10, p. 2919-2929TechnologyHyperspectral
DS202010-1831
2020
Ma, J.Cao, Y., Jung, H., Ma, J.Seismic properties of a unique olivine-rich eclogite in the western Gneiss region, Norway.Minerals ( MDPI), 10.339/min10090774 22p. PdfEurope, Norwayeclogites

Abstract: Investigating the seismic properties of natural eclogite is crucial for identifying the composition, density, and mechanical structure of the Earth’s deep crust and mantle. For this purpose, numerous studies have addressed the seismic properties of various types of eclogite, except for a rare eclogite type that contains abundant olivine and orthopyroxene. In this contribution, we calculated the ambient-condition seismic velocities and seismic anisotropies of this eclogite type using an olivine-rich eclogite from northwestern Flemsøya in the Nordøyane ultrahigh-pressure (UHP) domain of the Western Gneiss Region in Norway. Detailed analyses of the seismic properties data suggest that patterns of seismic anisotropy of the Flem eclogite were largely controlled by the strength of the crystal-preferred orientation (CPO) and characterized by significant destructive effects of the CPO interactions, which together, resulted in very weak bulk rock seismic anisotropies (AVp = 1.0-2.5%, max. AVs = 0.6-2.0%). The magnitudes of the seismic anisotropies of the Flem eclogite were similar to those of dry eclogite but much lower than those of gabbro, peridotite, hydrous-phase-bearing eclogite, and blueschist. Furthermore, we found that amphibole CPOs were the main contributors to the higher seismic anisotropies in some amphibole-rich samples. The average seismic velocities of Flem eclogite were greatly affected by the relative volume proportions of omphacite and amphibole. The Vp (8.00-8.33 km/s) and Vs (4.55-4.72 km/s) were remarkably larger than the hydrous-phase-bearing eclogite, blueschist, and gabbro, but lower than dry eclogite and peridotite. The Vp/Vs ratio was almost constant (avg. ? 1.765) among Flem eclogite, slightly larger than olivine-free dry eclogite, but similar to peridotite, indicating that an abundance of olivine is the source of their high Vp/Vs ratios. The Vp/Vs ratios of Flem eclogite were also higher than other (non-)retrograded eclogite and significantly lower than those of gabbro. The seismic features derived from the Flem eclogite can thus be used to distinguish olivine-rich eclogite from other common rock types (especially gabbro) in the deep continental crust or subduction channel when high-resolution seismic wave data are available.
DS200612-1558
2005
Ma, J.LXu, Y.G., Ma, J.L, Frey, F.A., Feigenson, M.D., Liu, J.F.Role of lithosphere asthenosphere interaction in the genesis of Quaternary alkali and tholeitic basalts from Datong, western North Chin a Craton.Chemical Geology, Vol. 224, 4, pp. 247-271.ChinaAlkalic
DS200612-1557
2006
Ma, J.L.Xu, Y.G., Blusztajn, J., Ma, J.L., Hart, S.R.In searching for old lithospheric relict beneath North Chin a Craton: Sr Nd Os isotopic composition of peridotite xenoliths from Yangyuan.Geochimica et Cosmochimica Acta, Vol. 70, 18, p. 3. abstract only.ChinaGeochronology
DS200812-1284
2008
Ma, J-L.Xu, Y-G., Blusztajn, J., Ma, J-L., Suzuki, K., Liu, J.F., Hart, S.R.Late Archean to Early Proterozoic lithospheric mantle beneath the western North Chin a craton: Sr Nd Os isotopes of peridotite xenoliths from Yangyuan and FansiLithos, Vol. 102, 3-4, pp.25-42.ChinaGeochronology
DS202105-0802
2021
Ma, J-L.Yu, Y., Huang, X-L., Sun, M., Ma, J-L.B isotopic constraints on the role of H2O in mantle wedge melting.Geochimica et Cosmochimica Acta, Vol. 303, pp. 92-109, pdfMantlemelting

Abstract: The role of water on melting in the mantle wedge is still debated due to large uncertainty on the estimates of H2O flux beneath arcs. B has been proven as an effective proxy for water flux because B and H2O show similar chemical behaviors during subduction. The Habahe mafic dikes from the Chinese Altai were emplaced within a narrow area (<20?km from south to north) during the northward subduction of the Junggar Ocean in the middle Paleozoic. These dikes have been classified into four types with distinct geochemical and Sr-Nd-Hf-Pb isotopic compositions, which originated from mantle sources metasomatized by different subduction components, including melts from subducted sediments (Type-I, Type-IV), fluids from subducted sediments (Type-II), and melts from subducted oceanic crust (Type-III). We present B content and isotope data for the Habahe mafic dikes to investigate the influence of subduction components on melting in the mantle wedge. Type-I and -III mafic dikes all have negative ?11B values (?7.7‰ to ?5.0‰) with variable B contents (3.65-13.4?ppm) and B/Nb ratios (2.10-7.39), indicating B isotopically light features for the subducted sediments and oceanic crust. Type-II mafic dikes have lower B contents (3.97-9.90?ppm) and higher B/Nb ratios (7.07-14.4) than Type-I mafic dikes, with a wide range of ?11B values from ?7.8‰ to ?2.7‰. This suggests that their mantle source may have been metasomatized by fluids from subducted serpentinite besides fluids from subducted sediments. Type-IV mafic dikes have higher B contents (17.0-27.5?ppm) and B/Nb ratios (25.0-40.8), and heavier B isotopic compositions (?11B?=??2.9‰ to +3.5‰) than Type-I mafic dikes. This indicates involvement of fluids from the slab serpentinite in metasomatism of their mantle source in addition to melts from the subducted sediments. The Habahe mafic dikes show wide range of B/Nb ratios, suggesting that different amounts of water were added into their mantle sources. These dikes exhibit variable Zr/Yb and Nb/Yb ratios, and constantly low TiO2/Yb, indicating their formation through different degrees melting of depleted mantle sources. Their Zr/Yb and Nb/Yb ratios are negatively correlated with B/Nb, which reflects elevation of the melting degree of their mantle sources as increasing water input. Similar trends are also observed in basalts from global arcs and their major and trace elements correlate well with B/Nb ratios. Thus, water flux should play an important role on melting in the mantle wedge and control magma compositions of the arcs.
DS200712-0659
2006
Ma, L.Ma, L.Developments and challenges of the Chin a diamond market.Gems & Gemology, 4th International Symposium abstracts, Fall 2006, p.25 abstract onlyChinaEconomics
DS201312-0561
2014
Ma, L.Ma, L., Jiang, S-Y., Hofman, A.W., Dai, B-Z., Hou, M-L., Zhao, K-D, Chen, L-H., Jiang, Y.H.Lithospheric and asthenospheric sources of lamprophyres in the Jiadong Peninsula: a consequence of rapid lithospheric thinning beneath the North Chin a craton?Geochimica et Cosmochimica Acta, Vol. 124, pp. 250-271.ChinaLamprophyre
DS201605-0863
2016
Ma, L.Ma, L., Jiang, S-Y., Hofmann, A.W., Xu, Y-G, Dai, B-Z., Hou, M-L.Rapid lithospheric thinning of North Chin a craton: new evidence from Cretaceous mafic dikes in the Jiaodong Peninsula.Chemical Geology, Vol. 432, pp. 1-15.ChinaDikes

Abstract: The North China Craton is a classic case for the destruction of an ancient craton, in that it records the loss of more than 100 km of ancient refractory lithospheric mantle during the late Mesozoic and early Cenozoic. However, the mechanisms for this lithospheric thinning remain controversial in large part due to the lack of any systematic investigations of the Mesozoic asthenospheric mantle via its derived mafic rocks, which are key to understand the thinning processes. In this paper, we present detailed zircon U-Pb geochronology, elemental geochemistry, and Sr-Nd-Hf isotopic data for lamprophyres and diabase-porphyries of the Jiaodong Peninsula, in the eastern North China Craton in order to place constraints on models for lithospheric thinning. Our results show that the lamprophyres and diabase-porphyries are derived from the convective asthenospheric mantle via different degrees of partial melting, and that this mantle source was previously modified by carbonatitic liquids. Zircon LA-ICP-MS U-Pb dating suggests an emplacement age for these rocks of 123-121 Ma, the earliest evidence for asthenospherically-derived melts in the Jiaodong Peninsula so far. This emplacement age indicates that the thickness of the lithosphere in the Jiaodong Peninsula was relatively thin at that time. Co-occurrence of the asthenospheric and lithospheric mantle-derived mafic rocks as well as high-Mg adakites record a rapid transition from lithospheric to asthenospheric mantle sources, indicating that the lithosphere beneath the Jiaodong Peninsula was rapidly detached just prior to ca. 120 Ma. Lithospheric thinning of the North China Craton may have been initiated from the Jiaodong Peninsula and Bohai Sea and then propagated towards the interior of the craton.
DS201012-0831
2010
Ma, L.J.Wang, L., Zhao, Y., Ding, J., Hao, J.,Ma, L.J., Zhang, L.X.Macrocrystal garnet and its inclusions in kimberlite pipes from the Mengyin area, Shandong Province, China.Acta Geologica Sinica, Vol. 84, 1, pp. 167-177.ChinaDeposit - Mengyin
DS201508-0351
2015
Ma, M.Dongre, A.N., Viljoen, K.S., Ma, M.The Pipe-15 kimberlite: a new addition to the Wajrakarur cluster of the Wajrakarur kimberlite field, Eastern Dharwar craton, southern India.Journal of the Geological Society of India, Vol. 86, 1, pp. 71-79.IndiaDeposit - Pipe-15
DS200712-0660
2007
Ma, P.Ma, P., Wang, P., Tenorio, L., de Hoop, M.V., Van der Hilst, R.D.Imaging of structure at and near the core mantle boundary using a generalized radon transform2. inference of singularities.Journal of Geophysical Research, Vol. 112, B8, B08403.MantleGeophysics - seismics
DS201212-0826
2012
Ma, Q.Zheng, J.P., Griffin, W.L., Ma, Q., O'Reilly, S.Y., Xiong, Q., Tang, H.Y., Zhao, J.H., Yu, C.M., Su, Y.P.Accretion and reworking beneath the North Chin a craton.Lithos, Vol. 149, pp. 61-78.ChinaAccretion
DS201803-0488
2018
Ma, Q.Yang, Y-H., Wu, F-Y., Yang, J-H., Mitchell, R.H., Zhao, Z-F., Xie, L-W., Huang, C., Ma, Q., Yang, M., Zhao, H.U-Pb age determination of schorlomite garnet by laser ablation inductively coupled plasma mass spectrometry. Magnet Cove, Fanshan, Ozernaya, Alno, Prairie LakeJournal of Analytical At. Spectrometry, Vol. 33, pp. 231-239.United States, Arkansas, China, Hebei, Russia, Kola Peninsula, Europe, Sweden, Canada, Ontariogeochronology

Abstract: We report the first U-Pb geochronological investigation of schorlomite garnet from carbonatite and alkaline complexes and demonstrate its applicability for U-Pb age determination using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) due to its relatively high U and Th abundances and negligible common Pb content. The comparative matrix effects of laser ablation of zircon and schorlomite are investigated and demonstrate the necessity of a suitable matrix-matched reference material for schorlomite geochronology. Laser-induced elemental fractional and instrumental mass discrimination were externally-corrected using an in house schorlomite reference material (WS20) for U-Pb geochronology. In order to validate the effectiveness and robustness of our analytical protocol, we demonstrate the veracity of U-Pb age determination for five schorlomite samples from: the Magnet Cove complex, Arkansas (USA); the Fanshan ultrapotassic complex, Hebei (China); the Ozernaya alkaline ultramafic complex, Kola Peninsula (Russia); the Alnö alkaline-rock carbonatite complex (Sweden); and the Prairie Lake carbonatite complex, Ontario (Canada). The schorlomite U-Pb ages range from 96 Ma to 1160 Ma, and are almost identical to ages determined from other accessory minerals in these complexes and support the reliability of our analytical protocol. Schorlomite garnet U-Pb geochronology is considered to be a promising new technique for understanding the genesis of carbonatites, alkaline rocks, and related rare-metal deposits.
DS201812-2844
2018
Ma, Q.Ma, Q., Xu, Y-G., Deng, Y,m Zhengm J-P., Sur, M., Griffin, W.L., Xia, B., Yan Wang, C.Similar crust beneath disrupted and intact cratons: arguments against lower crust delamination as a decratonization trigger. North China cratonTectonophysics, in press available 31p.Chinacraton

Abstract: The continental lithosphere is not forever; some cratons have lost their original roots during the course of their evolution. Yet, it is not clear whether gravitational instability of dense lower crust is the primary driver of decratonization. This is addressed here with emphasis being placed on the North China Craton (NCC), because it represents one of the best examples of craton-root disruption in the world, and a place where models can be tested. If lower-crustal delamination was the trigger for decratonization, we would expect a clear contrast in crustal structure and composition between disturbed (rootless) and intact cratons. However, the eastern (disturbed) and western (intact) parts of the NCC show virtually identical physical structure and composition (a thin mafic lower crust and a predominantly intermediate composition overall) although the crust in the disturbed part is thinner than in the intact craton. This suggests that delamination of the lower crust was not a viable mechanism of craton-root disruption in the NCC case. Indeed, the crust beneath the NCC largely resembles those of stable Archean cratons worldwide. Therefore the delamination, if it occurred, may have taken place much earlier (Archean) than previously thought, rather than in the Mesozoic. Delamination may have been a common phenomenon in the early evolution of cratons, probably due to relatively higher mantle temperatures in the Archean Eon.
DS201912-2835
2019
Ma, Q.Yang, Y-H., Wu, F-Y., Qiu-Li, L., Rojas-Agramonte, Y., Yang, J-H., Yang, L., Ma, Q., Xie, L-W., Huang, C., Fan, H-R., Zhao, Z-F., Xu, C.In situ U-Th-Pb dating and Sr-Nd isotope analysis of bastnasite by LA-(MC)-ICP-MS.Geostandards and Geoanalltical Research, Vol. 43, 3, pp. 543-565.China, Europe, Sweden, Asia, Mongolia, United States, Africa, Malawi, MadagascarREE

Abstract: Bastnäsite is the end member of a large group of carbonate-fluoride minerals with the common formula (REE) CO3F•CaCO3. This group is generally widespread and, despite never occurring in large quantities, represents the major economic light rare earth element (LREE) mineral in deposits related to carbonatite and alkaline intrusions. Since bastnäsite is easily altered and commonly contains inclusions of earlier?crystallised minerals, in situ analysis is considered the most suitable method to measure its U?Th?Pb and Sr?Nd isotopic compositions. Electron probe microanalysis and laser ablation (multi?collector) inductively coupled plasma?mass spectrometry of forty?six bastnäsite samples from LREE deposits in China, Pakistan, Sweden, Mongolia, USA, Malawi and Madagascar indicate that this mineral typically has high Th and LREE and moderate U and Sr contents. Analysis of an in?house bastnäsite reference material (K?9) demonstrated that precise and accurate U?Th?Pb ages could be obtained after common Pb correction. Moreover, the Th?Pb age with its high precision is preferable to the U?Pb age because most bastnäsites have relatively high Th rather than U contents. These results will have significant implications for understanding the genesis of endogenous ore deposits and formation processes related to metallogenic geochronology research.
DS202111-1774
2021
Ma, R-L.Ma, R-L., Chen, W.T., Zhang, W., Chen, Y-W.Hydrothermal upgrading as an important tool for the REE mineralization in the Miaoya carbonatite - syenite complex, central China.American Mineralogist, Vol. 106, pp. 1690-1703.Chinadeposit - Miaoya

Abstract: Secondary hydrothermal reworking of REEs has been widely documented in carbonatites/alkaline rocks, but its potential role in the REE mineralization associated with these rocks is currently poorly understood. This study conducted a combined textural and in situ chemical investigation on the REE mineralization in the ~430 Ma Miaoya carbonatite-syenite complex, central China. Our study shows that the REE mineralization, dated at ~220 Ma, is characterized by a close association of REE minerals (monazite and/or bastnäsite) with pervasive carbonatization overprinting the carbonatites and syenites. In these carbonatites and syenites, both the apatite and calcite, which are the dominant magmatic REE-bearing minerals, exhibit complicated internal textures that are generally composed of BSE-bright and BSE-dark domains. Under BSE imaging, the former domains are homogeneous and free of pores or mineral inclusions, whereas the latter have a high porosity and inclusions of monazite and/or bastnäsite. In situ chemical analyses show that the BSE-dark domains of the apatite and calcite have light REE concentrations and (La/Yb)N values much lower than the BSE-bright areas. These features are similar to those observed in metasomatized apatite from mineral-fluid reaction experiments, thus indicating that the BSE-dark domains formed from primary precursors (i.e., represented by the BSE-bright domains) through a fluid-aided, dissolution-reprecipitation process during which the primary light REEs are hydrothermally remobilized. New, in situ Sr-Nd isotopic results of apatite and various REE minerals, in combination with mass balance calculations, strongly suggest that the remobilized REEs are responsible for the subsequent hydrothermal REE mineralization in the Miaoya complex. Investigations of fluid inclusions show that the fluids responsible for the REE mobilization and mineralization are CO2-rich, with medium temperatures (227-340 °C) and low salinities (1.42-8.82 wt‰). Such a feature, in combination with C-O isotopic data, indicates that the causative fluids are likely co-genetic with fluids from coeval orogenic Au-Ag deposits (220-200 Ma) in the same tectonic unit. Our new findings provide strong evidence that the late hydrothermal upgrading of early cumulated REEs under certain conditions could also be an important tool for REE mineralization in carbonatites, particularly for those present in convergent belts where faults (facilitating fluid migration) and hydrothermal fluids are extensively developed.
DS200712-0661
2007
Ma, S.Ma, S., Eaton, D.W.Western Quebec seismic zone ( Canada): clustered, midcrustal seismicity along a Mesozoic hot spot track.Journal of Geophysical Research, Vol. 112, B6, B06305.Canada, QuebecGeophysics - seismics
DS201512-1937
2015
Ma, W.Mackay, D.A.R., Simandl, G.J.,Ma, W., Gravel, J., Redfearn, M.Indicator minerals in exploration for speciality metal deposits: a QEMSCAN approach.Symposium on critical and strategic materials, British Columbia Geological Survey Paper 2015-3, held Nov. 13-14, pp. 211-218.TechnologyRare earths

Abstract: Quantitative Evaluation of Materials by Scanning electron microscopy (QEMSCAN®) was used to assess carbonatite indicator minerals in fl uvial sediments from the drainage area of the Aley carbonatite, in north-central British Columbia. QEMSCAN® is a viable method for rapid detection and characterization of carbonatite indicator minerals with minimal processing other than dry sieving. Stream sediments from directly above, and up to 11 km downstream, of the carbonatite deposit were selected for this indicator mineral study. The geology of the Aley carbonatite is described by Mäder (1986), Kressal et al. (2010), McLeish (2013), Mackay and Simandl (2014), and Chakhmouradian et al. (2015). Traditional indicator mineral exploration methods use the 0.25-2.0 mm size fraction of unconsolidated sediments (Averill, 2001, 2014; McCurdy, 2006, 2009; McClenaghan, 2011, 2014). Indicator minerals are detectable by QEMSCAN® at particle sizes smaller than those used for hand picking (<0.25 mm). Pre-concentration (typically by shaker table) is used before heavy liquid separation, isodynamic magnetic separation, optical identifi cation using a binocular microscope, and hand picking (McClenaghan, 2011). Following additional sieving, the 0.5-1 and 1-2 mm fractions are hand picked for indicator minerals while the 0.25-0.5 mm fraction is subjected to paramagnetic separation before hand picking (Averill, 2001; McClenaghan, 2011). Hand picking indicator minerals focuses on monomineralic grains, and composite grains may be lost during processing. Composite grains are diffi cult and time consuming to hand pick and characterize using optical and Scanning Electron Microscopy (SEM) methods. A single grain mount can take 6-12 hours to chemically analyse (Layton- Matthews et al., 2014). Detailed sample analysis using the QEMSCAN® Particle Mineral Analysis routine allows for 5-6 samples to be analyzed per day. When only mineral identifi cation and mineral concentrations and counts are required, the use of a Bulk Mineral Analysis routine reduces the analysis time from ~4 hours to ~30 minutes per sample.
DS201605-0864
2016
Ma, W.Mackay, D.A.R., Simandl, G.J., Ma, W., Redfearn, M., Gravel, J.Indicator mineral-based exploration for carbonatites and related specialty metal deposits - a QEMSCAN orientation survey, British Columbia. Aley, Lonnie, WicheedaJournal of Geochemical Exploration, Vol. 165, pp. 159-173.Canada, British ColumbiaGeochemistry - carbonatites

Abstract: This orientation survey indicates that Quantitative Evaluation of Materials by Scanning electron microscopy (QEMSCAN®) is a viable alternative to traditional indicator mineral exploration approaches which involve complex processing followed by visual indicator mineral hand-picking with a binocular microscope. Representative polished smear sections of the 125-250 ?m fraction (dry sieved and otherwise unprocessed) and corresponding Mozley C800 table concentrates from the drainages of three carbonatites (Aley, Lonnie, and Wicheeda) in the British Columbia Alkaline Province of the Canadian Cordillera were studied. Polished smear sections (26 × 46 mm slide size) contained an average of 20,000 exposed particles. A single section can be analyzed in detail using the Particle Mineral Analysis routine in approximately 3.5-4.5 h. If only mineral identification and mineral concentrations are required, the Bulk Mineral Analysis routine reduces the analytical time to 30 min. The most useful carbonatite indicator minerals are niobates (pyrochlore and columbite), REE-fluorocarbonates, monazite, and apatite. Niobate minerals were identified in the 125-250 ?m fraction of stream sediment samples more than 11 km downstream from the Aley carbonatite (their source) without the need for pre-concentration. With minimal processing by Mozley C800, carbonatite indicator minerals were detected downstream of the Lonnie and Wicheeda carbonatites. The main advantages of QEMSCAN® over the traditional indicator mineral exploration techniques are its ability to: 1) analyze very small minerals, 2) quickly determine quantitative sediment composition and mineralogy by both weight percent and mineral count, 3) establish mineral size distribution within the analyzed size fraction, and 4) determine the proportions of monomineralic (liberated) grains to compound grains and statistically assess mineral associations in compound grains. One of the key advantages is that this method permits the use of indicator minerals based on their chemical properties. This is impossible to accomplish using visual identification.
DS1983-0423
1983
Ma, WENYUN.Ma, WENYUN.A Tentative Model for the Formation of Quaternary Valley Placer Diamond Deposits.Geological Review., Vol. 29, No. 6, PP. 545-552.ChinaAlluvial Diamond Placers
DS1998-0909
1998
Ma, X.Ma, X., Bai, J.Precambrian crustal evolution of China. revised by A.C. CadmanSpringer, 336p. $ 160.00ChinaBook - ad, Precambrian geology
DS201801-0063
2017
Ma, X.Simandl, G.J., Mackay, D.A.R., Ma, X., Luck, P., Gravel, J., Akam, C.The direct indicator mineral concept and QEMSCAN applied to exploration for carbonatite and carbonatite related ore deposits.in: Ferbey, T. Plouffe, A., Hickein, A.S. eds. Indicator minerals in tills and stream sediments of the Canadian Cordillera. Geological Association of Canada Special Paper,, Vol. 50, pp. 175-190.Canada, British Columbiacarbonatite - Aley, Lonnie, Wicheeda

Abstract: This volume consists of a series of papers of importance to indicator minerals in the Canadian Cordillera. Topics include the glacial history of the Cordilleran Ice Sheet, drift prospecting methods, the evolution of survey sampling strategies, new analytical methods, and recent advances in applying indicators minerals to mineral exploration. This volume fills a notable knowledge gap on the use of indicator minerals in the Canadian Cordillera. We hope that the volume serves as a user guide, encouraging the wider application of indicator minerals by the exploration community.
DS200812-0812
2008
Ma, Y.Oganov, A.R., Ono, S., Ma, Y., Glass, C.W., Garcia, A.Novel high pressure structures of MgCo3, CaCo3 and CO2 and their role in Earth's lower mantle.Earth and Planetary Science Letters, Vol. 273, pp. 38-47.MantleUHP, Carbon storage
DS200912-0554
2008
Ma, Y.Organoc, A.R., Ono, S., Ma, Y.Where is the mantle's carbon?American Geological Union, Fall meeting Dec. 15-19, Eos Trans. Vol. 89, no. 53, meeting supplement, 1p. abstractMantleReduction
DS201112-1100
2011
Ma, Y.Wang, K., Fan, H., Yang, K., Hu, F., Ma, Y.Bayan Obo carbonatites: texture evidence from polyphase intrusive and extrusive carbonatites.Acta Geologica Sinica, Vol. 84, 6, pp. 1365-1376.Asia, ChinaCarbonatite
DS201312-0347
2012
Ma, Y.Guo, S., Ye, K., Wu, Y., Chen, Y., Yang, Y., Zhang, L., Liu, J., Mao, Q., Ma, Y.A potential method to confirm the previous existence of lawsonite in eclogite: the mass imbalance of Sr and LREEs in multi stage epidote ( Ganghe, Dabie UHP terrane).Journal of Metamorphic Gology, Vol. 31, 4, pp. 415-435.ChinaUHP
DS201412-0383
2014
Ma, Y.Huang, Q., Yu, D., Xu, B., Hu, W., Ma, Y., Wang, Y., Zhao, Z., Wen, B., He, J., Liu, Z., Tian, Y.Nanotwinned diamond with unprecedented hardness and stability.Nature, Vol. 510, June 12, pp. 250-253.TechnologyDiamond synthetic
DS201804-0747
2017
Ma, Y.Tang, S., Song, Z., Lu, T., Su, J., Ma, Y.Two natural type IIa diamonds with strong phosphorescence and Ni related defects.Gems & Gemology Lab Notes, Vol. 53, 4, pp. 476-478.Technologyfluoresecence

Abstract: Strong phosphorescence under UV excitation is rarely seen in natural diamond and normally limited to hydrogen-rich type Ia or type IaA/Ib chameleons and type IIb diamonds (T. Hainschwang et al., "A gemological study of a collection of chameleon diamonds," Spring 2005 G&G, pp. 20-35; S. Eaton-Magaña and R. Lu, "Phosphorescence in type IIb diamonds," Diamond and Related Materials, Vol. 20, No. 7, 2011, pp. 983-989). When seen in other diamond types, an even rarer occurrence, it is shorter and less intense. Recently, the National Gemstone Testing Center (NGTC) in Beijing encountered two natural diamonds that showed extraordinarily strong blue phosphorescence and uncommon fluorescence colors under the DiamondView.
DS201808-1792
2018
Ma, Y.Tang, S., Su, J., Lu, T., Ma, Y., Ke, J., Song, Z., Zhang, S., Liu, H.A thick overgrowth of CVD synthetic diamond on a natural diamond.Journal of Gemmology, Vol. 36, 2, pp. 134-141.Technologysynthetics

Abstract: In October 2017, a natural diamond overgrown by a thick layer of CVD synthetic diamond was identified at the Beijing laboratory of the National Gemstone Testing Center (NGTC). The round-brilliant-cut sample was near-colourless and weighed 0.11 ct. No sign of the overgrowth was observed with magnification. However, DiamondView images showed a distinct boundary in the pavilion separating layers of different luminescence: The upper layer displayed red fluorescence with greenish blue phosphorescence, while the lower portion showed deep blue fluorescence and no phosphorescence. Infrared spectroscopy revealed that the upper layer was type IIa and the lower portion was type Ia. Ultraviolet-visible-near infrared (UV-Vis-NIR) spectroscopy recorded an unusual co-existence of the N3 centre at 415 nm together with absorption due to [Si-V]-defects at 737 nm. The photoluminescence (PL) spectrum confirmed a high level of [Si-V]-defects. The approximate thickness of the CVD synthetic layer was ~740 µm, which is much thicker than previously reported for such overgrowths. The presence of the N3 centre in the natural diamond layer caused this sample to be passed as natural by various screening instruments. Luminescence imaging is key to identifying such overgrowths, and should be relied upon more heavily in the screening procedures used by gemmological laboratories in the future.
DS202001-0047
2020
Ma, Y.Wang, X., Xiao, Y., Sun, Y., Wang, Y., Liu, J., Yang, K., Gu, H., Hou, Z., Tian, Y., Wu, W., Ma, Y.Initiation of the North China craton destruction: constraints from the diamond bearing alkaline basalts from Langan, China.Gondwana Research, Vol. 80, pp. 228-243.Chinacraton

Abstract: The North China Craton (NCC) is an atypical ancient landmass that suffered lithospheric destruction. Previous studies suggest that the eastern part of the lithospheric mantle of the NCC has been thinned and modified in the Mesozoic. However, the initiation time and mechanism of the destruction remain controversial. Mafic magmatismcould provide a unique windowinto deciphering the lithospheric mantle composition and its evolution. Here we present geochemical and geochronological data of the diamond-bearing alkaline basalts from Lan'gan, located in the southeastern margin of the NCC. Zircon U-Pb dating yielded an average age of 174 ± 14 Ma, representing the first reported Jurassic basalts in the eastern NCC. The Lan'gan basalts are enriched in light rare earth elements (LREE) and large ion lithosphile elements (LILE). Sr-Nd-Pb-Hf isotopic compositions (87Sr/86Sr(t) = 0.70646-0.70925, ?Nd(t) = ?2.1 to ?4.9, 206Pb/204Pb(t) = 17.14-18.12, 207Pb/204Pb(t) = 15.28-15.61, 208Pb/204Pb(t) = 37.82-38.67, and zircon ?Hf(t) = ?17 to ?21) are enriched compared to depleted mantle. The presence of primary amphibole indicates that the magma source of the basalts was water enriched. These observations suggest that, the lithospheric mantle of the eastern NCC were significantly refertilized, likely by slab derived fluids/melts fromthe Paleo-Pacific subduction. Owing to the Paleo-Pacific subduction, the lithosphericmantle of the eastern NCCwere reduced in viscosity and intensity, and finally promoted partialmelting in a limited scale to generate the investigated alkaline basalts. Hence, the discovery of diamond in the Lan'gan basalts demonstrates that the lithosphere of the NCC remained thick, and that large-scale destruction had not initiated in the early Jurassic beneath this region.
DS202004-0542
2020
Ma, Y.Wang, X., Xiao, Y., Wang, Y., Liu, J., Yang, K., Gu, H., Hou, Z., Tian, Y., Wu, W., Ma, Y.Initiation of the North China Craton destruction: constraints from the diamond bearing alkaline basalts from Langan China.Gondwana Research, Vol. 80, pp. 228-243.Chinadeposit - Langan

Abstract: The North China Craton (NCC) is an atypical ancient landmass that suffered lithospheric destruction. Previous studies suggest that the eastern part of the lithospheric mantle of the NCC has been thinned and refertilized in the Mesozoic. However, the initiation time and mechanism of the destruction remain controversial. Mafic magmatism could provide a unique window into deciphering the lithospheric mantle composition and its evolution. Here we present geochemical and geochronological data of the diamond-bearing alkaline basalts from Lan'gan, located in the southeastern margin of the NCC. Zircon UPb dating yielded an average age of 174?±?14?Ma, representing the first reported Jurassic basalts in the eastern NCC. The Lan'gan basalts are enriched in light rare earth elements (LREE) and large ion lithosphile elements (LILE). Sr-Nd-Pb-Hf isotopic compositions (87Sr/86Sr(t)?=?0.70646-0.70925, ?Nd(t)?=??2.1 to ?4.9, 206Pb/204Pb(t)?=?17.14-18.12, 207Pb/204Pb(t)?=?15.28-15.61, 208Pb/204Pb(t)?=?37.82-38.67, and zircon ?Hf(t)?=??17 to ?21) are slightly enriched compared to depleted mantle. The presence of primary amphibole indicates that the magma source of the basalts was water enriched. These observations suggest that, the lithospheric mantle of the eastern NCC were significantly refertilized, likely by slab derived fluids/melts from the Paleo-Pacific subduction. Owing to the Paleo-Pacific subduction, the lithospheric mantle of the eastern NCC were reduced in viscosity and intensity, and finally promoted partial melting in a limited scale to generate the investigated alkaline basalts. Hence, the discovery of diamond in the Lan'gan basalts demonstrates that the lithosphere of the NCC remained thick, and that large-scale destruction had not initiated in the early Jurassic beneath this region.
DS200512-0665
2004
Ma, Z.Ma, Z., Gao, X.Some thoughts on the research on continental tectonics, oceanic tectonics and earth tectonics.Earth Science Frontiers, Vol. 11, 4, pp. 9-14. Ingenta 1045384804ChinaTectonics
DS1980-0221
1980
Ma DaquanMa DaquanComparative Study of Pyropes in Kimberlites from Eastern Chin a and Discussion on Their Genetic Conditions.Chi. Acad. Geol. Sci. Bulletin., SER. 8, Vol. 1, No. 1, PP. 26-38. 18 REFS.China, Guizhou, Songhe, Hubei, Henan, Shandong, LiaoningMineral Chemistry, Garnet, Pyrope
DS1983-0420
1983
Ma daquanMa daquan, ZHAO ZIJIE, Xu tao, LU DENGGRONG.On the Petrological Characteristics of Micaceous Kimberlite and Accompanied Meta-alkaline Ultrabasic Rocks at Maping, Quizhou Province.Bulletin. Institute GEOL. GEOL. (CHINESE ACAD. GEOL. SCI.), No. 7, PP. 65-75.China, QuizhouMineralogy, Petrology, Micaceous
DS1983-0421
1983
Ma daquanMa daquan, ZHAO ZIJIE, Xu tao, LU DENGRONG.The petrological characteristics of micaceous kimberlite and accompanied meta alkaline ultrabasic rocks at Maping, Guizhou.*CHIBulletin. Yichang Institute Geol. and Min. Res.*CHI, Vol. 7, pp. 65-75ChinaPetrology, Kimberlite
DS1991-0797
1991
Ma KaiyiJiang Mei, Ma KaiyiThe magnetic lineament map of Chin a and adjacent sea areasGlobal tectonics and Metallogeny, Vol. 3, No. 4, July, pp. 193-211ChinaStructure -lineament, Geophysics -magnetics
DS1983-0422
1983
Ma WenyumMa WenyumModel Experiment for the Formation of Quaternary Diamond Placers.*chiDizhi Lunping, *CHI, Vol. 29, No. 6, pp. 545-552ChinaPlacer, Diamond
DS1981-0275
1981
Ma xingyuan, WU ZHENGWEN.Ma xingyuan, WU ZHENGWEN.Early Tectonic Evolution of ChinaPrecambrian Research, Vol. 14, PP. 185-202.ChinaRegional Structure, Geotectonics
DS202106-0965
2021
Maacha, L.Pujol-Sola, N., Dominguez-Carretero, D., Proenza, J.A., Haissen, F., Ikenne, M., Gonzales-Jiminez, J.M., Colas, V., Maacha, L., Garcia-Casco, A.The chromitites of the Neoproterozoic Bou Azzer ophiolite ( central Anti-Atlas, Morocco) revisited.Ore Geology Reviews, Vol. 134, 104166, 24p. PdfAfrica, Moroccomoissanite

Abstract: The Neoproterozoic Bou Azzer ophiolite in the Moroccan Anti-Atlas Panafrican belt hosts numerous chromitite orebodies within the peridotite section of the oceanic mantle. The chromitites are strongly affected by serpentinization and metamorphism, although they still preserve igneous relicts amenable for petrogenetic interpretation. The major, minor and trace element composition of unaltered chromite cores reveal two compositional groups: intermediate-Cr (Cr# = 0.60 - 0.74) and high-Cr (Cr# = 0.79 - 0.84) and estimates of parental melt compositions suggest crystallization from pulses of fore-arc basalts (FAB) and boninitic melts, respectively, that infiltrated the oceanic supra-subduction zone (SSZ) mantle. A platinum group elements (PGE) mineralization dominated by Ir-Ru-Os is recognized in the chromitites, which has its mineralogical expression in abundant inclusions of Os-Ir alloys and coexisting magmatic laurite (RuS2) and their products of metamorphic alteration. Unusual mineral phases in chromite, not previously reported in this ophiolite, include super-reduced and/or nominally ultra-high pressure minerals moissanite (SiC), native Cu and silicates (oriented clinopyroxene lamellae), but “exotic” zircon and diaspore have also been identified. We interpret that clinopyroxene lamellae have a magmatic origin, whereas super-reduced phases originated during serpentinization processes and diaspore is linked to late circulation of low-silica fluids related to rodingitization. Zircon grains, on the other hand, with apatite and serpentine inclusions, could either have formed after the interaction of chromitite with mantle-derived melts or could represent subducted detrital sediments later incorporated into the chromitites. We offer a comparison of the Bou Azzer chromitites with other Precambrian ophiolitic chromitites worldwide, which are rather scarce in the geological record. The studied chromitites are very similar to the Neoproterozoic chromitites reported in the Arabian-Nubian shield, which are also related to the Panafrican orogeny. Thus, we conclude that the Bou Azzer chromitites formed in a subduction-initiation geodynamic setting with two-stages of evolution, with formation of FAB-derived intermediate-Cr chromitites in the early stage and formation of boninite-derived high-Cr chromitites in the late stage.
DS1950-0110
1952
Maack, R.Maack, R.Die Entwicklung der Gondwana Schichten Sued brasiliens und Ihre Beziehungen zur Karru-formation Suedafrikas.International GEOL. CONGRRESS 19TH. SYMPOSIUM SUR LES SERIES DE GO, PP. 341-372.South AfricaGeomorphology
DS200812-0231
2007
Maake, L.Compton, J.S., Maake, L.Source of the suspended load of the upper Orange River, South Africa.South African Journal of Geology, Vol. 110, 2-3, Sept. pp. 339-348.Africa, South AfricaGeomorphology
DS1987-0230
1987
Maaloe, S.Furnes, H., Pedersen, R.B., Maaloe, S.Petrology and geochemistry of spinel peridotite nodules and host basalt, VestspitsbergenNorsk Geologisk Tidsskrift, Vol. 66, pp. 53-68NorwayMineral Chemistry
DS1987-0429
1987
Maaloe, S.Maaloe, S.The generation and shape of feeder dykes from mantle sourcesContributions to Mineralogy and Petrology, Vol. 96, No. 1, pp. 47-55GlobalMantle, Dike
DS1995-1132
1995
Maaloe, S.Maaloe, S.Geochemical aspects of primary magma accumulation from extended sourceregionsGeochimica et Cosmochimica Acta, Vol. 59, No. 24, Dec. 1, pp. 5091-5102MantleMagma, Geochemistry
DS1998-0910
1998
Maaloe, S.Maaloe, S.Extraction of primary abyssal tholeiite from a stratified plumeJournal of Geology, Vol. 106, No. 2, March pp. 163-179.MantleHarzburgite, Melt layers, plumes
DS1998-0911
1998
Maaloe, S.Maaloe, S.Melt dynamics of a layered mantle plume sourceContributions to Mineralogy and Petrology, Vol. 133, No. 1-2, pp. 83-95.MantlePlume, Geodynamics
DS2002-1012
2002
MaasMatteini, M., Mazzuoli, R., Omarini, R., Cas, R., MaasThe geochemical variations of the upper Cenozoic volcanism along Calama Olacapato El Toro transversalTectonophysics, Vol.345,1-4,Feb.15, pp. 211-27.AndesGeodynamics - tectonics, fault system, Petrogenetic
DS1996-0463
1996
Maas, R.Foster, J.G., Lambert, D.D., Maas, R.Rhenium- Osmium (Re-Os) isotopic evidence for genesis of Archean nickel ores from uncontaminated komatiitesNature, Vol. 382, No. 6593, Aug. 22, pp. 703-705AustraliaNickel, komatiites, Geochronology
DS1997-0706
1997
Maas, R.Maas, R., Nicholls, I.A., Legg, C.Igneous and metamorphic enclaves in the S type Deddick granodiorite Lach lanfold belt, petrographic, geochem.Journal of Petrology, Vol. 38, No. 7, July pp. 815-842AustraliaGeochronology, crustal melting, Magma mixing
DS1998-1558
1998
Maas, R.Waight, T.E., Weaver, S.D., Maas, R., Eby, G.N.French Creek granite and Hohanu Dyke swarm: Late Cretaceous alkaline magmatism and opening of Tasman SeaAustralian Journal of Earth Sciences, Vol. 45, No. 6, Dec. pp. 823-36.GlobalAlkaline rocks
DS2002-0804
2002
Maas, R.Kamenetsky, V.S., Maas, R.Mantle melt evolution (dynamic source) in the origin of single MORB suite: a perspective from magnesian glasses of MacQuarie Island.Journal of Petrology, Vol. 43, No. 10, Oct.pp. 1909-22.Australia, MacQuarie IslandMelt - chemistry
DS200512-0495
2004
Maas, R.Kamenetsky, M.B., Sobolev, A.V., Kamenetsky, V.S., Maas, R., Danyushevsky, L.V., Thomas, R., Pokhilenko, N.P., Sobolev, N.V.Kimberlite melts rich in alkali chlorides and carbonates: a potent metasomatic agent in the mantle.Geology, Vol. 32, 10, Oct. pp. 845-848.Russia, Siberia, YakutiaUdachnaya, Group I, volatiles, metasomatism, inclusions
DS200512-0666
2005
Maas, R.Maas, R., Kamenetsky, M.B., Sobolev, A.V., Kamenetsky, V.S., Sobolev, N.V.Sr Nd Pb isotope evidence for a mantle origin of alkali chlorides and carbonates in the Udachnaya kimberlite, Siberia.Geology, Vol. 33, 7, July, pp. 549-552.Russia, SiberiaGeochronology - Udachnaya
DS200612-0660
2006
Maas, R.Kamenetsky, V.S., Kamenetsky, M.B., Sharygin, V.V., Maas, R., Faure, K., Sobolev, A.V.Why are Udachnaya East pipe kimberlites enriched in Cl and alkalis but poor in H2O?Geochimica et Cosmochimica Acta, Vol. 70, 18, p. 3. abstract only.Russia, YakutiaDeposit - Udachnaya mineral chemistry
DS200712-0662
2007
Maas, R.Maas, R., Kamenetsky, V.S., Sharygin, V.V.Recycled oceanic crust as a possible source of kimberlites - isotopic evidence from perovskite, Udachnaya-East pipe, Siberia.Plates, Plumes, and Paradigms, 1p. abstract p. A608.Russia, SiberiaUdachnaya-East
DS200812-0539
2008
Maas, R.Kamenetsky, V.S., Kamenetsky, M.B., Golovin, A.V., Maas, R., Sharygin, V.V., Pokhilenko, N.P.Salty kimberlite of the Udachnaya East pipe ( Yakutia, Russia): a petrological oddity, victim of contamination or a new magma type?9IKC.com, 3p. extended abstractRussiaDeposit - Udachnaya - taste!
DS200812-0542
2008
Maas, R.Kamenetsky, V.S., Maas, R.The merits of 'recycled oceanic crust - eclogite' lineage in the mantle source of group I kimberlite melts.Goldschmidt Conference 2008, Abstract p.A446.Russia, SiberiaDeposit - Udachnaya-East
DS200812-0694
2008
Maas, R.Maas, R., Kamenetsky, V., Paton, C., Sharygin, V.Low 87Sr 86 Sr in kimberlitic perovskite - further evidence for recycled oceanic crust as a possible source of kimberlites.9IKC.com, 3p. extended abstractRussiaDeposit - Udachnaya
DS200912-0113
2008
Maas, R.Chesler, R., Hergt, J., Phillips, D., Maas, R.The geochemistry of the West Australian, West Kimberley province lamproites.Geological Society of Australia Abstracts, Vol. 90, p. 35. abs.AustraliaLamproite
DS201212-0347
2012
Maas, R.Kamenetsky, V.S., Kamenetsky, M.B., Golovin, A.V., Shaygin, V.V., Maas, R.Ultrafresh salty kimberlite of the Udachnaya-East pipe ( Yakutia, Russia): a petrological oddity or fortuitous discovery?Lithos, Vol. 152, pp. 173-186.RussiaDeposit - Udachnaya-East
DS201312-0313
2013
Maas, R.Giuliani, A., Kamenetsky, V.S., Kendrick, M.A., Phillips, D., Wyatt, B.A., Maas, R.Oxide, sulphide and carbonate minerals in a mantle polymict breccia: metasomatism by proto-kimberlite magmas, and relationship to the kimberlite megacrystic suite.Chemical Geology, Vol. 353, pp. 4-18.Africa, South AfricaKimberley district
DS201312-0314
2013
Maas, R.Giuliani, A., Phillips, D., Kendrick, M.K., Maas, R., Greig, A., Armstrong, R., Felgate, M.R., Kamenetsky, V.S.Dating mantle metasomatism: a new tool ( U/PB LIMA Titanate) and an imposter ( 40Ar/39Ar phlogopite).Goldschmidt 2013, AbstractMantleMetasomatism
DS201312-0344
2013
Maas, R.Guiliani, A., Phillips, D., Fiorentini, M.L., Kendrick, M.A., Maas, R., Wing, B.A., Woodhead, J.D., Bui, T.H., Kamenetsky, V.S.Mantle oddities: a sulphate fluid preserved in a MARID xenolith from the Bultfontein kimberlite ( Kimberley South Africa).Earth and Planetary Science Letters, Vol. 376, pp. 74-86.Africa, South AfricaDeposit - Bultfontein
DS201412-0296
2014
Maas, R.Giuliani, G., Phillips, D., Maas, R., Woodhead, J.D., Kendrick, M.A., Greig, A., Armstrong, R.A., Chew, D., Kamenetsky, V.S., Fiorentini, M.I.LIMA U-Pb ages link lithospheric mantle metasomatism to Karoo magmatism beneath the Kimberley region, South Africa.Earth and Planetary Science Letters, Vol. 401, pp. 132-147.Africa, South AfricaKimberlite
DS201412-0439
2014
Maas, R.Kamenetsky, V.S., Golovin, A.V., Maas, R., Giuliani, A., Kamenetsky, M.B., Weiss, Y.Towards a new model for kimberlite petrogenesis: evidence from unaltered kimberlites and mantle minerals. Earth Science Reviews, Vol. 139, pp. 145-151.Russia, YakutiaDeposit - Udachnaya
DS201412-1006
2013
Maas, R.Yaxley, G.M., Kamenetsky, V.S., Nichols, G.T., Maas, R., Belousova, E., Rosenthal, A., Norman, M.The discovery of kimberlites in Antarctica extends the vast Gondwanan Cretaceous province.Nature Communications, Dec. 17, 7p.AntarcticaPrince Charles Mountains
DS201509-0405
2015
Maas, R.Kamenetsky, V.S., Mitchell, R.H., Maas, R., Giuliani, A., Gaboury, D., Zhitova, L.Chlorine in mantle derived carbonatite melts revealed by halite in the St. Honore intrusion ( Quebec, Canada).Geology, Vol. 43, 8, pp. 687-690.Canada, QuebecCarbonatite

Abstract: Mantle-derived carbonatites are igneous rocks dominated by carbonate minerals. Intrusive carbonatites typically contain calcite and, less commonly, dolomite and siderite as the only carbonate minerals. In contrast, lavas erupted by the only active carbonatite volcano on Earth, Oldoinyo Lengai, Tanzania, are enriched in Na-rich carbonate phenocrysts (nyerereite and gregoryite) and Na-K halides in the groundmass. The apparent paradox between the compositions of intrusive and extrusive carbonatites has not been satisfactorily resolved. This study records the fortuitous preservation of halite in the intrusive dolomitic carbonatite of the St.-Honoré carbonatite complex (Québec, Canada), more than 490 m below the present surface. Halite occurs intergrown with, and included in, magmatic minerals typical of intrusive carbonatites; i.e., dolomite, calcite, apatite, rare earth element fluorocarbonates, pyrochlore, fluorite, and phlogopite. Halite is also a major daughter phase of melt inclusions hosted in early magmatic minerals, apatite and pyrochlore. The carbon isotope composition of dolomite (?13C = –5.2‰) and Sr-Nd isotope compositions of individual minerals (87Sr/86Sri = 0.70287 in apatite, to 0.70443 in halite; ?Nd = +3.2 to +4.0) indicate a mantle origin for the St.-Honoré carbonatite parental melt. More radiogenic Sr compositions of dolomite and dolomite-hosted halite and heavy oxygen isotope composition of dolomite (?18O = +23‰) suggest their formation at some time after magma emplacement by recrystallization of original magmatic components in the presence of ambient fluids. Our observations indicate that water-soluble chloride minerals, common in the modern natrocarbonatite lavas, can be significant but ephemeral components of intrusive carbonatite complexes. We therefore infer that the parental magmas that produce primary carbonatite melts might be enriched in Na and Cl. This conclusion affects existing models for mantle source compositions, melting scenarios, temperature, rheological properties, and crystallization path of carbonatite melts.
DS201606-1119
2016
Maas, R.Soltys, A., Giuliani, A., Phillips, D., Kamenetsky, V.S., Maas, R., Woodhead, J., Rodemann, T.In-situ assimilation of mantle minerals by kimberlitic magmas - direct evidence from a garnet wehrlite xenolith entrained in the Bultfontein kimberlite ( Kimberley, South Africa).Lithos, Vol. 256-257, pp. 182-196.Africa, South AfricaDeposit - Bultfontein

Abstract: The lack of consensus on the possible range of initial kimberlite melt compositions and their evolution as they ascend through and interact with mantle and crustal wall rocks, hampers a complete understanding of kimberlite petrogenesis. Attempts to resolve these issues are complicated by the fact that kimberlite rocks are mixtures of magmatic, xenocrystic and antecrystic components and, hence, are not directly representative of their parental melt composition. Furthermore, there is a lack of direct evidence of the assimilation processes that may characterise kimberlitic melts during ascent, which makes understanding their melt evolution difficult. In this contribution we provide novel constraints on the interaction between precursor kimberlite melts and lithospheric mantle wall rocks. We present detailed textural and geochemical data for a carbonate-rich vein assemblage that traverses a garnet wehrlite xenolith [equilibrated at ~ 1060 °C and 43 kbar (~ 140-145 km)] from the Bultfontein kimberlite (Kimberley, South Africa). This vein assemblage is dominated by Ca-Mg carbonates, with subordinate oxide minerals, olivine, sulphides, and apatite. Vein phases have highly variable compositions indicating formation under disequilibrium conditions. Primary inclusions in the vein minerals and secondary inclusion trails in host wehrlite minerals contain abundant alkali-bearing phases (e.g., Na-K bearing carbonates, Mg-freudenbergite, Na-bearing apatite and phlogopite). The Sr-isotope composition of vein carbonates overlaps those of groundmass calcite from the Bultfontein kimberlite, as well as perovskite from the other kimberlites in the Kimberley area. Clinopyroxene and garnet in the host wehrlite are resorbed and have Si-rich reaction mantles where in contact with the carbonate-rich veins. Within some veins, the carbonates occur as droplet-like, globular segregations, separated from a similarly shaped Si-rich phase by a thin meniscus of Mg-magnetite. These textures are interpreted to represent immiscibility between carbonate and silicate melts. The preservation of reaction mantles, immiscibility textures and disequilibrium in the vein assemblage, suggests quenching, probably triggered by entrainment and rapid transport toward the Earth's surface in the host kimberlite magma. Based on the Sr-isotope systematics of vein carbonate minerals, and the close temporal relationship between carbonate-rich metasomatism and kimberlite magmatism, we suggest that the carbonate-rich vein assemblage was produced by the interaction between a melt genetically related to the Bultfontein kimberlite and wehrlitic mantle wall rock. If correct, this unique xenolith sample provides a rare snapshot of the assimilation processes that might characterise parental kimberlite melts during their ascent through the lithospheric mantle.
DS201610-1877
2016
Maas, R.Kamenetsky, V.S., Maas, R., Kamenetsky, M.B., Yaxley, G.M., Ehrig, K., Zellmer, G.F., Bindeman, I.N., Sobolev, A.V., Kuzmin, D.V., Ivanov, A.V., Woodhead, J., Schilling, J-G.Multiple mantle sources of continental magmatism: insights from "high-Ti" picrites of Karoo and other large igneous provinces.Chemical Geology, in press available 10p.Africa, South AfricaLIP magmatism

Abstract: Magmas forming large igneous provinces (LIP) on continents are generated by extensive melting in the deep crust and underlying mantle and associated with break-up of ancient supercontinents, followed by formation of a new basaltic crust in the mid-oceanic rifts. A lack of the unifying model in understanding the sources of LIP magmatism is justified by lithological and geochemical complexity of erupted magmas on local (e.g. a cross-section) and regional (a single and different LIP) scales. Moreover, the majority of LIP rocks do not fit general criteria for recognizing primary/primitive melts (i.e. < 8 wt% MgO and absence of high-Fo olivine phenocrysts). This study presents the mineralogical (olivine, Cr-spinel, orthopyroxene), geochemical (trace elements and Sr-Nd-Hf-Pb isotopes) and olivine-hosted melt inclusion compositional characteristics of a single primitive (16 wt% MgO), high-Ti (2.5 wt% TiO2) picrite with high-Mg olivine (up to 91 mol% Fo) from the Letaba Formation in the ~ 180 Ma Karoo LIP (south Africa). The olivine compositions (unusually high ?18O (6.17‰), high NiO (0.36-0.56 wt%) and low MnO and CaO (0.12-0.20 and 0.12-0.22 wt%, respectively)) are used to argue for a non-peridotitic mantle source. This is supported by the enrichment of the rock and melts in most incompatible trace elements and depletion in heavy rare earth elements (e.g. high Gd/Yb) that reflects residual garnet in the source of melting. The radiogenic isotopes resemble those of the model enriched mantle (EM-1) and further argue for a long-term enrichment of the source in incompatible trace elements. The enriched high-Ti compositions, strongly fractionated incompatible trace elements, presence of primitive olivine and high-Cr spinel in the Letaba picrites are closely matched by olivine-phyric rocks from the ~ 260 Ma Emeishan (Yongsheng area, SW China) and ~ 250 Ma Siberian (Maimecha-Kotuy region, N Siberia) LIPs. However, many other compositional parameters (e.g. trace element and ?18O compositions of olivine phenocrysts, Fe2 +/Fe3 + in Cr-spinel, Sr-Nd-Hf isotope ratios) only partially overlap or even diverge. We thus imply that parental melts of enriched picritic rocks with forsteritic olivine from three major continental igneous provinces - Karoo, Emeishan and Siberia cannot be assigned to a common mantle source and similar melting conditions. The Karoo picrites also exhibit some mineralogical and geochemical similarities with rocks and glasses in the south Atlantic Ridge and adjacent fracture zones. The geodynamic reconstructions of the continental plate motions since break-up of the Gondwanaland in the Jurassic support the current position of the source of the Karoo magmatism in the southernmost Atlantic. Co-occurrence of modern and recent anomalous rocks with normal mid-ocean ridge basalts in this region can be related to blocks/rafts of the ancient lithosphere, stranded in the ambient upper mantle and occasionally sampled by rifting-related decompressional melting.
DS201611-2110
2016
Maas, R.Giuliani, A., Soltys, A., Phillips, D., Kamenetsly, V.S., Maas, R., Geomann, K., Woodhead, J.D., Drysdale, R.N., Griffin, W.L.The final stages of kimberlite petrogenesis: petrography, mineral chemistry, melt inclusions and Sr-C-O isotope geochemistry of the Bultfontein kimberlite ( Kimberley, South Africa).Chemical Geology, in press available 15p.Africa, South AfricaDeposit - Bultfontein

Abstract: The petrogenesis of kimberlites commonly is obscured by interaction with hydrothermal fluids, including deuteric (late-magmatic) and/or groundwater components. To provide new constraints on the modification of kimberlite rocks during overprinting by such fluids and on the fractionation of kimberlite magmas during crystallisation, we have undertaken a detailed petrographic and geochemical study of a hypabyssal sample (BK) from the Bultfontein kimberlite (Kimberley, South Africa).
DS201707-1327
2017
Maas, R.Giuliani, A., Soltys, A., Phillips, D., Kamenetsky, V.S., Maas, R., Goemann, K., Woodhead, J.D., Drysdale, R.N., Griffin, W.L.The final stages of kimberlite petrogenesis: petrography, mineral chemistry, melt inclusions and Sr-C-O isotope geochemistry of the Bultfontein kimberlite ( Kimberley, South Africa.Chemical Geology, Vol. 455, pp. 342-256.Africa, South Africadeposit - Bultfontein

Abstract: The petrogenesis of kimberlites is commonly obscured by interaction with hydrothermal fluids, including deuteric (late-magmatic) and/or groundwater components. To provide new constraints on the modification of kimberlite rocks during fluid interaction and the fractionation of kimberlite magmas during crystallisation, we have undertaken a detailed petrographic and geochemical study of a hypabyssal sample (BK) from the Bultfontein kimberlite (Kimberley, South Africa). Sample BK consists of abundant macrocrysts (> 1 mm) and (micro-) phenocrysts of olivine and lesser phlogopite, smaller grains of apatite, serpentinised monticellite, spinel, perovskite, phlogopite and ilmenite in a matrix of calcite, serpentine and dolomite. As in kimberlites worldwide, BK olivine grains consist of cores with variable Mg/Fe ratios, overgrown by rims that host inclusions of groundmass phases (spinel, perovskite, phlogopite) and have constant Mg/Fe, but variable Ni, Mn and Ca concentrations. Primary multiphase inclusions in the outer rims of olivine and in Fe-Ti-rich (‘MUM’) spinel are dominated by dolomite, calcite and alkali carbonates with lesser silicate and oxide minerals. Secondary inclusions in olivine host an assemblage of Na-K carbonates and chlorides. The primary inclusions are interpreted as crystallised alkali-Si-bearing Ca-Mg-rich carbonate melts, whereas secondary inclusions host Na-K-rich C-O-H-Cl fluids. In situ Sr-isotope analyses of groundmass calcite and perovskite reveal similar 87Sr/86Sr ratios to perovskite in the Bultfontein and the other Kimberley kimberlites, i.e. magmatic values. The ?18O composition of the BK bulk carbonate fraction is above the mantle range, whereas the ?13C values are similar to those of mantle-derived magmas. The occurrence of different generations of serpentine and occasional groundmass calcite with high 87Sr/86Sr, and elevated bulk carbonate ?18O values indicate that the kimberlite was overprinted by hydrothermal fluids, which probably included a significant groundwater component. Before this alteration the groundmass included calcite, monticellite, apatite and minor dolomite, phlogopite, spinel, perovskite and ilmenite. Inclusions of groundmass minerals in olivine rims and phlogopite phenocrysts show that olivine and phlogopite also belong to the magmatic assemblage. We therefore suggest that the crystallised kimberlite was produced by an alkali-bearing, phosphorus-rich, silica-dolomitic melt. The alkali-Si-bearing Ca-Mg-rich carbonate compositions of primary melt inclusions in the outer rims of olivine and in spinel grains with evolved compositions (MUM spinel) support formation of these melts after fractionation of abundant olivine, and probably other phases (e.g., ilmenite and chromite). Finally, the similarity between secondary inclusions in kimberlite olivine of this and other worldwide kimberlites and secondary inclusions in minerals of carbonatitic, mafic and felsic magmatic rocks, suggests trapping of residual Na-K-rich C-O-H-Cl fluids after groundmass crystallisation. These residual fluids may have persisted in pore spaces within the largely crystalline BK groundmass and subsequently mixed with larger volumes of external fluids, which triggered serpentine formation and localised carbonate recrystallisation.
DS201707-1337
2017
Maas, R.Kamenetsky, V.S., Maas, R., Kamenetsky, M.B., Yaxley, G.M., Ehrig, K., Zellmer, G.F., Bindeman, I.N., Sobolev, A.V., Kuzmin, D.V., Ivanov, A.V., Woodhead, J., Schilling, J-G.Multiple mantle sources of continental magmatism: insights from high Ti picrites of Karoo and other large igneous provinces.Chemical Geology, Vol. 455, pp. 22-31.Africa, South Africamagmatism

Abstract: Magmas forming large igneous provinces (LIP) on continents are generated by extensive melting in the deep crust and underlying mantle and associated with break-up of ancient supercontinents, followed by formation of a new basaltic crust in the mid-oceanic rifts. A lack of the unifying model in understanding the sources of LIP magmatism is justified by lithological and geochemical complexity of erupted magmas on local (e.g. a cross-section) and regional (a single and different LIP) scales. Moreover, the majority of LIP rocks do not fit general criteria for recognizing primary/primitive melts (i.e. < 8 wt% MgO and absence of high-Fo olivine phenocrysts). This study presents the mineralogical (olivine, Cr-spinel, orthopyroxene), geochemical (trace elements and Sr-Nd-Hf-Pb isotopes) and olivine-hosted melt inclusion compositional characteristics of a single primitive (16 wt% MgO), high-Ti (2.5 wt% TiO2) picrite with high-Mg olivine (up to 91 mol% Fo) from the Letaba Formation in the ~ 180 Ma Karoo LIP (south Africa). The olivine compositions (unusually high ?18O (6.17‰), high NiO (0.36–0.56 wt%) and low MnO and CaO (0.12–0.20 and 0.12–0.22 wt%, respectively)) are used to argue for a non-peridotitic mantle source. This is supported by the enrichment of the rock and melts in most incompatible trace elements and depletion in heavy rare earth elements (e.g. high Gd/Yb) that reflects residual garnet in the source of melting. The radiogenic isotopes resemble those of the model enriched mantle (EM-1) and further argue for a long-term enrichment of the source in incompatible trace elements. The enriched high-Ti compositions, strongly fractionated incompatible trace elements, presence of primitive olivine and high-Cr spinel in the Letaba picrites are closely matched by olivine-phyric rocks from the ~ 260 Ma Emeishan (Yongsheng area, SW China) and ~ 250 Ma Siberian (Maimecha-Kotuy region, N Siberia) LIPs. However, many other compositional parameters (e.g. trace element and ?18O compositions of olivine phenocrysts, Fe2 +/Fe3 + in Cr-spinel, Sr-Nd-Hf isotope ratios) only partially overlap or even diverge. We thus imply that parental melts of enriched picritic rocks with forsteritic olivine from three major continental igneous provinces – Karoo, Emeishan and Siberia cannot be assigned to a common mantle source and similar melting conditions. The Karoo picrites also exhibit some mineralogical and geochemical similarities with rocks and glasses in the south Atlantic Ridge and adjacent fracture zones. The geodynamic reconstructions of the continental plate motions since break-up of the Gondwanaland in the Jurassic support the current position of the source of the Karoo magmatism in the southernmost Atlantic. Co-occurrence of modern and recent anomalous rocks with normal mid-ocean ridge basalts in this region can be related to blocks/rafts of the ancient lithosphere, stranded in the ambient upper mantle and occasionally sampled by rifting-related decompressional melting.
DS201708-1583
2017
Maas, R.Woodhead, J., Hergt, J., Guiliani, A., Phillips, D., Maas, R.Tracking continental style scale modification of the Earth's mantle using zircon megacrysts. KimberlitesGeochemical Perspectives Letters, Vol. 4, pp. 1-6.Africa, South Africa, Zimbabwemetasomatism, geochronology

Abstract: Metasomatism, the chemical alteration of rocks by a variety of melts and fluids, has formed a key concept in studies of the Earth’s mantle for decades. Metasomatic effects are often inferred to be far-reaching and yet the evidence for their occurrence is usually based upon individual hand specimens or suites of rocks that display considerable heterogeneity. In rare cases, however, we are offered insights into larger-scale chemical modifications that occur in the mantle. Here we utilise the Lu–Hf systematics of zircon megacrysts erupted in kimberlite magmas to discern two temporally and compositionally discrete metasomatic events in the mantle beneath southern Africa, each having an influence extending over an area exceeding one million km2. These data provide unambiguous evidence for metasomatic processes operating at continental scales and seemingly unperturbed by the age and composition of the local lithospheric mantle. The most recent of these events may be associated with the major Jurassic-Karoo magmatism in southern Africa.
DS201801-0017
2017
Maas, R.Giuliani, A., Campeny, M., Kamenetsky, V.S., Afonso, J.C., Maas, R., Melgarejo, J.C., Kohn, B.P., Matchen, E.L., Mangas, J., Goncalves, A.O., Manuel, J.Southwestern Africa on the burner: Pleistocene carbonatite volcanism linked to deep mantle upwelling in Angola.Geology, Vol. 45, 11, pp. 971=974.Africa, Angolacarbonatite - Catanda

Abstract: The origin of intraplate carbonatitic to alkaline volcanism in Africa is controversial. A tectonic control, i.e., decompression melting associated with far-field stress, is suggested by correlation with lithospheric sutures, repeated magmatic cycles in the same areas over several million years, synchronicity across the plate, and lack of clear age progression patterns. Conversely, a dominant role for mantle convection is supported by the coincidence of Cenozoic volcanism with regions of lithospheric uplift, positive free-air gravity anomalies, and slow seismic velocities. To improve constraints on the genesis of African volcanism, here we report the first radiometric and isotopic results for the Catanda complex, which hosts the only extrusive carbonatites in Angola. Apatite (U-Th-Sm)/He and phlogopite 40Ar/39Ar ages of Catanda aillikite lavas indicate eruption at ca. 500-800 ka, more than 100 m.y. after emplacement of abundant kimberlites and carbonatites in this region. The lavas share similar high-? (HIMU)-like Sr-Nd-Pb-Hf isotope compositions with other young mantle-derived volcanics from Africa (e.g., Northern Kenya Rift; Cameroon Line). The position of the Catanda complex in the Lucapa corridor, a long-lived extensional structure, suggests a possible tectonic control for the volcanism. The complex is also located on the Bié Dome, a broad region of fast Pleistocene uplift attributed to mantle upwelling. Seismic tomography models indicate convection of deep hot material beneath regions of active volcanism in Africa, including a large area encompassing Angola and northern Namibia. This is strong evidence that intraplate late Cenozoic volcanism, including the Catanda complex, resulted from the interplay between mantle convection and preexisting lithospheric heterogeneities.
DS201803-0450
2014
Maas, R.Giuliani, A., Phillips, D., Maas, R., Woodhead, J.D., Kendrick, M.A., Greig, A., Armstrong, R.A., Chew, D., Kamenetsky, V.S., Fiorentini, M.L.LIMA U-Pb ages link lithospheric mantle metasomatism to Karoo magmatism beneath the Kimberley region, South Africa.Earth and Planetary Science Letters, Vol. 401, pp. 132-147.Africa, South Africametasomatism

Abstract: The Karoo igneous rocks (174-185 Ma) of southern Africa represent one of the largest continental flood basalt provinces on Earth. Available evidence indicates that Karoo magmas either originated in the asthenosphere and were extensively modified by interaction with the lithospheric mantle prior to emplacement in the upper crust; or were produced by partial melting of enriched mantle lithosphere. However, no direct evidence of interaction by Karoo melts (or their precursors) with lithospheric mantle rocks has yet been identified in the suites of mantle xenoliths sampled by post-Karoo kimberlites in southern Africa. Here we report U-Pb ages for lindsleyite-mathiasite (LIMA) titanate minerals (crichtonite series) from three metasomatised, phlogopite and clinopyroxene-rich peridotite xenoliths from the ?84 Ma Bultfontein kimberlite (Kimberley, South Africa), located in the southern part of the Karoo magmatic province. The LIMA minerals appear to have formed during metasomatism of the lithospheric mantle by fluids enriched in HFSE (Ti, Zr, Hf, Nb), LILE (K, Ba, Ca, Sr) and LREE. LIMA U-Pb elemental and isotopic compositions were measured in situ by LA-ICP-MS methods, and potential matrix effects were evaluated by solution-mode analysis of mineral separates. LIMA minerals from the three samples yielded apparent U-Pb ages of , and (). A single zircon grain extracted from the ?190 Ma LIMA-bearing sample produced a similar U-Pb age of , within uncertainty of the LIMA ages. These data provide the first robust evidence of fluid enrichment in the lithospheric mantle beneath the Kimberley region at ?180-190 Ma, and suggest causation of mantle metasomatism by Karoo melts or their precursor(s). The results further indicate that U-Pb dating of LIMA minerals provides a new, accurate tool for dating metasomatic events in the lithospheric mantle.
DS201803-0451
2018
Maas, R.Giuliani, A., Woodhead, J.D., Phillips, D., Maas, R., Davies, G.R.Titanates of the lindsleyite mathiasite ( LIMA) group reveal isotope disequilibrium associated with metasomatism in the mantle beneath Kimberley ( South Africa).Earth and Planetary Science Letters, Vol. 482, pp. 253-264.Africa, South Africametasomatism

Abstract: Radiogenic isotope variations unrelated to radiogenic ingrowth are common between minerals found in metasomatised mantle xenoliths entrained in kimberlite, basalts and related magmas. As the metasomatic minerals are assumed to have been in isotopic equilibrium originally, such variations are typically attributed to contamination by the magma host and/or interaction with mantle fluids during or before xenolith transport to surface. However, the increasing evidence of metasomatism by multiple, compositionally distinct fluids permeating the lithospheric mantle, coeval with specific magmatic events, suggests that isotopic disequilibrium might be a consequence of discrete, though complex, metasomatic events. Here we provide clear evidence of elemental and Sr isotope heterogeneity between coeval Ti-rich LIMA (lindsleyite–mathiasite) minerals at the time of their formation in the mantle. LIMA minerals occur in close textural association with clinopyroxene and phlogopite in low-temperature (?800–900?°C), strongly metasomatised mantle xenoliths from the ?84 Ma Bultfontein kimberlite (South Africa). Previous U/Pb dating of the LIMA phases was used to argue that each xenolith recorded a single event of LIMA crystallisation at ?180–190 Ma, coeval with the emplacement of Karoo magmas. SEM imaging reveals that up to four types of LIMA phases coexist in each xenolith, and occasionally in a single LIMA grain. Major element and in situ Sr isotope analyses of the different LIMA types show that each phase has a distinct elemental composition and initial 87Sr/86Sr ratio (e.g., 0.7068–0.7086 and 0.7115–0.7129 for two LIMA types in a single xenolith; 0.7053-0.7131 across the entire sample suite). These combined age and isotopic constraints require that multiple fluids metasomatised these rocks at broadly the same time (i.e. within a few thousands to millions of years), and produced similar mineralogical features. Elemental and isotopic variations between different LIMA types could be due to interaction between one (or more) Karoo-related Ti-rich silicate melts and previously metasomatised, phlogopite-rich lithospheric mantle. This study demonstrates that mantle metasomatic assemblages seemingly generated in a single event may instead result from the infiltration of broadly coeval fluids with variable compositions. This in turn implies that the isotopic variations recorded in mantle rocks may be an inherent feature of metasomatism, and that hot fluids infiltrating a rock do not necessarily cause equilibration at the cm scale, as has been assumed previously. Simple modelling of solid-state diffusion in mantle minerals shows that isotopic disequilibrium may be preserved for up to hundreds of Myr at mantle lithosphere temperatures (?1100–1200?°C), unless subsequently affected by transient heating and/or fluid infiltration events. Radiogenic isotope disequilibrium associated with mantle metasomatism may therefore be a common feature of mantle xenoliths.
DS201807-1489
2018
Maas, R.Farr, H., Phillips, D., Maas, R., de Wit, M.Petrography, Sr isotope geochemistry and geochronology of the Nxau-Nxau kimberlites, north west Botswana.Mineralogy and Petrology, June 14, DOI:10.1007/ s00710-018- 0593-8, 14p.Africa, Botswanadeposit - Nxau

Abstract: The Nxau Nxau kimberlites in northwest Botswana belong to the Xaudum kimberlite province that also includes the Sikereti, Kaudom and Gura kimberlite clusters in north-east Namibia. The Nxau Nxau kimberlites lie on the southernmost extension of the Congo Craton, which incorporates part of the Damara Orogenic Belt on its margin. The Xaudum kimberlite province is geographically isolated from other known clusters but occurs within the limits of the NW-SE oriented, Karoo-aged Okavango Dyke Swarm and near NE-SW faults interpreted as the early stages of the East African Rift System. Petrographic, geochronological and isotopic studies were undertaken to characterise the nature of these kimberlites and the timing of their emplacement. The Nxau Nxau kimberlites exhibit groundmass textures, mineral phases and Sr-isotope compositions (87Sr/86Sri of 0.7036?±?0.0002; 2?) that are characteristic of archetypal (Group I) kimberlites. U-Pb perovskite, 40Ar/39Ar phlogopite and Rb-Sr phlogopite ages indicate that the kimberlites were emplaced in the Cretaceous, with perovskite from four samples yielding a preferred weighted average U-Pb age of 84?±?4 Ma (2?). This age is typical of many kimberlites in southern Africa, indicating that the Xaudum occurrences form part of this widespread Late Cretaceous kimberlite magmatic province. This time marks a significant period of tectonic stress reorganisation that could have provided the trigger for kimberlite magmatism. In this regard, the Nxau Nxau kimberlites may form part of a NE-SW oriented trend such as the Lucapa corridor, with implications for further undiscovered kimberlites along this corridor.
DS201812-2797
2018
Maas, R.Das, H., Kobussen, A.F., Webb, K.J., Phillips, D., Maas, R., Soltys, A., Rayner, M.J., Howell, D.Bunder deposit: The Bunder diamond project, India: geology, geochemistry, and age of Saptarshi lamproite pipes.Society of Economic Geology Geoscience and Exploration of the Argyle, Bunder, Diavik, and Murowa Diamond Deposits, Special Publication no. 20, pp. 201-222.Indiadeposit - Bunder
DS201902-0271
2019
Maas, R.Fitzpayne, A., Giuliani, A., Maas, R., Hergt, J., Janney, P., Phillips, D.Progressive metasomatism of the mantle by kimberlite melts: Sr-Nd-Hf-Pb isotope compositions of MARID and PIC minerals.Earth and Planetary Science Letters, Vol. 506, pp. 15-26.Africa, South Africadeposit - Newlands, Kimberley, Bultfontein

Abstract: MARID (Mica-Amphibole-Rutile-Ilmenite-Diopside) and PIC (Phlogopite-Ilmenite-Clinopyroxene) rocks occur as mantle-derived xenoliths in kimberlites and other alkaline volcanic rocks. Both rock types are alkaline and ultramafic in composition. The H2O and alkali metal enrichments in MARID and PIC rocks, reflected in abundant phlogopite, have been suggested to be caused by extreme mantle metasomatism. Radiogenic (Sr-Nd-Hf-Pb) isotope and trace element compositions for mineral separates from MARID (clinopyroxene and amphibole) and PIC (clinopyroxene only) samples derived from Cretaceous kimberlites (Kimberley) and orangeites (Newlands) from South Africa are used here to examine the source(s) of mantle metasomatism. PIC clinopyroxene is relatively homogeneous, with narrow ranges in initial isotopic composition (calculated to the emplacement age of the host Bultfontein kimberlite; 87Sr/86Sri: 0.7037-0.7041; ?Ndi: +3.0 to +3.6; ?Hfi: +2.2 to +2.5; 206Pb/204Pbi: 19.72-19.94) similar to kimberlite values. This is consistent with PIC rocks representing peridotites modified by intense metasomatic interaction with kimberlite melts. The MARID clinopyroxene and amphibole separates () studied here display broader ranges in isotope composition (e.g., 87Sr/86Sri: 0.705-0.711; ?Ndi: ?11.0 to ?1.0; ?Hfi: ?17.9 to ?8.5; 206Pb/204Pbi: 17.33-18.72) than observed in previous studies of MARID rocks. The Nd-Hf isotope compositions of kimberlite-derived MARID samples fall below the mantle array (??Hfi between ?13.0 and ?2.4), a feature reported widely for kimberlites and other alkaline magmas. We propose that such displacements in MARID minerals result from metasomatic alteration of an initial “enriched mantle” MARID composition (i.e., 87Sr/86Sri = 0.711; ?Ndi = ?11.0; ?Hfi = ?17.9; and 206Pb/204Pbi = 17.3) by the entraining kimberlite magma (87Sr/86Sr; ?Nd; ?Hf; 206Pb/204Pb). A model simulating the flow of kimberlite magma through a mantle column, thereby gradually equilibrating the isotopic and chemical compositions of the MARID wall-rock with those of the kimberlite magma, broadly reproduces the Sr-Nd-Hf-Pb isotope compositions of the MARID minerals analysed here. This model also suggests that assimilation of MARID components could be responsible for negative ??Hfi values in kimberlites. The isotopic composition of the inferred initial MARID end-member, with high 87Sr/86Sr and low ?Nd, ?Hf, and 206Pb/204Pb, resembles those found in orangeites, supporting previous inferences of a genetic link between MARID-veined mantle and orangeites. The metasomatic agent that produced such compositions in MARID rocks must be more extreme than the EM-II mantle component and may relate to recycled material that experienced long-term storage in the lithospheric mantle.
DS201905-1017
2019
Maas, R.Boger, S.D., Maas, R., Pastuhov, M., Macey, P.H., Hirdes, W., Schulte, B., Fanning, C.M., Ferreira, C.A.M., Jenett, T., Dallwig, R.The tectonic domains of southern and western Madagascar.Precambrian Research, Vol. 327, pp. 144-175.Africa, Madagascarplate tectonics

Abstract: Southern and western Madagascar is comprised of five tectonic provinces that, from northeast to southwest, are defined by the: (i) Ikalamavony, (ii) Anosyen, (iii) Androyen, (iv) Graphite and (v) Vohibory Domains. The Ikalamavony, Graphite and Vohibory Domains all have intermediate and felsic igneous protoliths of tonalite-trondhjemite-granodiorite-granite composition, with positive ?Nd, and low Sr and Pb isotopic ratios. All three domains are interpreted to be the products of intra-oceanic island arc magmatism. The protoliths of the Ikalamavony and Graphite Domains formed repectively between c. 1080-980?Ma and 1000-920?Ma, whereas those of the Vohibory Domain are younger and date to between c. 670-630?Ma. Different post-formation geologic histories tie the Vohibory-Graphite and Ikalamavony Domains to opposite sides of the pre-Gondwana Mozambique Ocean. By contrast, the Androyen and Anosyen Domains record long crustal histories. Intermediate to felsic igneous protoliths in the Androyen Domain are of Palaeoproterozoic age (c. 2200-1800?Ma), of tonalite-trondhjemite-granodiorite-granite composition, and show negative ?Nd, moderate to high 87Sr/86Sr and variable Pb isotopic compositions. The felsic igneous protoliths of the Anosyen Domain are of granitic composition and, when compared to felsic gneisses of the Androyen Domain, show consistently lower Sr/Y and markedly higher Sr and Pb isotope ratios. Like the Vohibory and Graphite Domains, the Androyen Domain can be linked to the western side of the Mozambique Ocean, while the Anosyen Domain shares magmatic and detrital zircon commonalities with the Ikalamavony Domain. It is consequently linked to the opposing eastern side of this ocean. The first common event observed in all domains dates to c. 580-520?Ma and marks the closure of the Mozambique Ocean. The trace of this suture lies along the boundary between the Androyen and Anosyen Domains and is defined by the Beraketa high-strain zone.
DS201910-2257
2019
Maas, R.Fitzpayne, A., Giuliani, A., Maas, R., Hergt, J., Janney, P., Phillips, D.Progressive metasomatism of the mantle by kimberliitic melts: Sr-Nd-Hf-Pb isotopic composition of MARID and PIC minerals.Goldschmidt2019, 1p. AbstractMantlemetasomatism

Abstract: MARID (Mica-Amphibole-Rutile-Ilmenite-Diopside) and PIC (Phlogopite-Ilmenite-Clinopyroxene) rocks occur as mantle-derived xenoliths in kimberlites and other alkaline volcanic rocks. Both rock types are alkaline and ultramafic in composition. The H2O and alkali metal enrichments in MARID and PIC rocks, reflected in abundant phlogopite, have been suggested to be caused by extreme mantle metasomatism. Radiogenic (Sr-Nd-Hf-Pb) isotope and trace element compositions for mineral separates from MARID (clinopyroxene and amphibole) and PIC (clinopyroxene only) samples derived from Cretaceous kimberlites (Kimberley) and orangeites (Newlands) from South Africa are used here to examine the source(s) of mantle metasomatism. PIC clinopyroxene ( n = 4 ) is relatively homogeneous, with narrow ranges in initial isotopic composition (calculated to the emplacement age of the host Bultfontein kimberlite; 87Sr/86Sri: 0.7037-0.7041; ?Ndi: +3.0 to +3.6; ?Hfi: +2.2 to +2.5; 206Pb/204Pbi: 19.72-19.94) similar to kimberlite values. This is consistent with PIC rocks representing peridotites modified by intense metasomatic interaction with kimberlite melts. The MARID clinopyroxene ( n = 9 ) and amphibole separates ( n = 11 ) studied here display broader ranges in isotope composition (e.g., 87Sr/86Sri: 0.705-0.711; ?Ndi: ?11.0 to ?1.0; ?Hfi: ?17.9 to ?8.5; 206Pb/204Pbi: 17.33-18.72) than observed in previous studies of MARID rocks. The Nd-Hf isotope compositions of kimberlite-derived MARID samples fall below the mantle array (??Hfi between ?13.0 and ?2.4), a feature reported widely for kimberlites and other alkaline magmas. We propose that such displacements in MARID minerals result from metasomatic alteration of an initial “enriched mantle” MARID composition (i.e., 87Sr/86Sri = 0.711; ?Ndi = ?11.0; ?Hfi = ?17.9; and 206Pb/204Pbi = 17.3) by the entraining kimberlite magma (87Sr/86Sr ? i 0.704 ; ?Nd ? i + 3.3 ; ?Hf ? i + 2.3 ; 206Pb/204Pb ? i 19.7 ). A model simulating the flow of kimberlite magma through a mantle column, thereby gradually equilibrating the isotopic and chemical compositions of the MARID wall-rock with those of the kimberlite magma, broadly reproduces the Sr-Nd-Hf-Pb isotope compositions of the MARID minerals analysed here. This model also suggests that assimilation of MARID components could be responsible for negative ??Hfi values in kimberlites. The isotopic composition of the inferred initial MARID end-member, with high 87Sr/86Sr and low ?Nd, ?Hf, and 206Pb/204Pb, resembles those found in orangeites, supporting previous inferences of a genetic link between MARID-veined mantle and orangeites. The metasomatic agent that produced such compositions in MARID rocks must be more extreme than the EM-II mantle component and may relate to recycled material that experienced long-term storage in the lithospheric mantle.
DS201910-2308
2019
Maas, R.Woodhead, J., Hergt, J., Giuliani, A., Maas, R., Philips, D., Pearson, D.G., Nowell, G.Kimberlites reveal 2.5-nillion year evolution of a deep, isolated mantle reservoir.Nature, Vol. 573, pp. 578-581.Mantlemelting

Abstract: The widely accepted paradigm of Earth's geochemical evolution states that the successive extraction of melts from the mantle over the past 4.5 billion years formed the continental crust, and produced at least one complementary melt-depleted reservoir that is now recognized as the upper-mantle source of mid-ocean-ridge basalts1. However, geochemical modelling and the occurrence of high 3He/4He (that is, primordial) signatures in some volcanic rocks suggest that volumes of relatively undifferentiated mantle may reside in deeper, isolated regions2. Some basalts from large igneous provinces may provide temporally restricted glimpses of the most primitive parts of the mantle3,4, but key questions regarding the longevity of such sources on planetary timescales—and whether any survive today—remain unresolved. Kimberlites, small-volume volcanic rocks that are the source of most diamonds, offer rare insights into aspects of the composition of the Earth’s deep mantle. The radiogenic isotope ratios of kimberlites of different ages enable us to map the evolution of this domain through time. Here we show that globally distributed kimberlites originate from a single homogeneous reservoir with an isotopic composition that is indicative of a uniform and pristine mantle source, which evolved in isolation over at least 2.5 billion years of Earth history—to our knowledge, the only such reservoir that has been identified to date. Around 200 million years ago, extensive volumes of the same source were perturbed, probably as a result of contamination by exogenic material. The distribution of affected kimberlites suggests that this event may be related to subduction along the margin of the Pangaea supercontinent. These results reveal a long-lived and globally extensive mantle reservoir that underwent subsequent disruption, possibly heralding a marked change to large-scale mantle-mixing regimes. These processes may explain why uncontaminated primordial mantle is so difficult to identify in recent mantle-derived melts.
DS201911-2575
2019
Maas, R.Woodhead, J., Hergt, J., Giuliani, A., Maas, R., Phillips, D., Pearson, D.G., Nowell, G.Kimberlites reveal 2.5 billion year evolution of a deep, isolated mantle reservoir.Nature , Vol. 573, pp. 578-581.Mantlediamond genesis

Abstract: The widely accepted paradigm of Earth's geochemical evolution states that the successive extraction of melts from the mantle over the past 4.5 billion years formed the continental crust, and produced at least one complementary melt-depleted reservoir that is now recognized as the upper-mantle source of mid-ocean-ridge basalts1. However, geochemical modelling and the occurrence of high 3He/4He (that is, primordial) signatures in some volcanic rocks suggest that volumes of relatively undifferentiated mantle may reside in deeper, isolated regions2. Some basalts from large igneous provinces may provide temporally restricted glimpses of the most primitive parts of the mantle3,4, but key questions regarding the longevity of such sources on planetary timescales—and whether any survive today—remain unresolved. Kimberlites, small-volume volcanic rocks that are the source of most diamonds, offer rare insights into aspects of the composition of the Earth’s deep mantle. The radiogenic isotope ratios of kimberlites of different ages enable us to map the evolution of this domain through time. Here we show that globally distributed kimberlites originate from a single homogeneous reservoir with an isotopic composition that is indicative of a uniform and pristine mantle source, which evolved in isolation over at least 2.5 billion years of Earth history—to our knowledge, the only such reservoir that has been identified to date. Around 200 million years ago, extensive volumes of the same source were perturbed, probably as a result of contamination by exogenic material. The distribution of affected kimberlites suggests that this event may be related to subduction along the margin of the Pangaea supercontinent. These results reveal a long-lived and globally extensive mantle reservoir that underwent subsequent disruption, possibly heralding a marked change to large-scale mantle-mixing regimes. These processes may explain why uncontaminated primordial mantle is so difficult to identify in recent mantle-derived melts.
DS202002-0174
2019
Maas, R.Dalton, H., Giuliani, A., O'Brien, H., Phillips, D., Maas, R. Petrogenesis of a hybrid cluster of evolved kimberlites and ultramafic lamprophyres in the Kuusamo area, Finland. Kasma 45, Kasma 45 south, Kasma 47, Kalettomanpuro, Kattaisenvaara, Dike 15 and LampiJournal of Petrology, in press available, 79p. PdfEurope, Finlanddeposit - Kuusamo

Abstract: Kimberlites are often closely associated, both in time and space, with a wide variety of alkaline ultramafic rock types; yet the question of a genetic relationship between these rock types remains uncertain. One locality where these relationships can be studied within the same cluster is the Karelian craton in Finland. In this study we present the first petrographic, mineral and whole-rock geochemical results for the most recently discovered kimberlite cluster on this craton, which represents an example of the close spatial overlap of kimberlites with ultramafic lamprophyres. The Kuusamo cluster incorporates seven bodies (Kasma 45, Kasma 45 south, Kasma 47, Kalettomanpuro (KP), Kattaisenvaara (KV), Dike 15 and Lampi) distributed along a 60?km NE-SW corridor. Hypabyssal samples from KV, KP, Kasma 45 and Kasma 47 consist of altered olivine macrocrysts and microcrysts and phlogopite phenocrysts in a groundmass of perovskite, apatite, spinel, ilmenite, serpentine, and calcite. These petrographic features combined with mineral (e.g., Mg-rich ilmenite, Al-Ba-rich, Ti-Fe-poor mica) and whole-rock incompatible trace element compositions (La/Nb = 0.8 ± 0.1; Th/Nb = 0.07 ± 0.01; Nb/U = 66 ± 9) are consistent with these rocks being classified as archetypal kimberlites. These Kuusamo kimberlites are enriched in CaO and poor in MgO, which combined with the absence of chromite and paucity of olivine macrocrysts and mantle-derived xenocrysts (including diamonds), suggest derivation from differentiated magmas after crystal fractionation. Samples from Lampi share similar petrographic features, but contain mica with compositions ranging from kimberlitic (Ba-Al-rich cores) to those more typical of orangeites/lamproites (increasing Si-Fe, decreasing Al-Ti-Ba), and have higher bulk-rock SiO2 contents than the Kuusamo kimberlites. These features, combined with the occurrence of quartz and titanite in the groundmass, indicate derivation from a kimberlite magma that underwent considerable crustal contamination. This study shows that crustal contamination can modify kimberlites by introducing features typical of alkaline ultramafic rock types. Dike 15 represents a distinct carbonate-rich lithology dominated by phlogopite over olivine, with lesser amounts of titaniferous clinopyroxene and manganoan ilmenite. Phlogopite (Fe-Ti-rich) and spinel (high Fe2+/Fe2++Mg) compositions are also distinct from the other Kuusamo intrusions. The petrographic and geochemical features of Dike 15 are typical of ultramafic lamprophyres, specifically, aillikites. Rb-Sr dating of phlogopite in Dike 15 yields an age of 1178.8 ± 4.1?Ma (2?), which is considerably older than the ?750?Ma emplacement age of the Kuusamo kimberlites. This new age indicates significant temporal overlap with the Lentiira-Kuhmo-Kostomuksha olivine lamproites emplaced ?100?km to the southeast. It is suggested that asthenospheric aillikite magmas similar to Dike 15 evolved to compositions akin to the Karelian orangeites and olivine lamproites through interaction with and assimilation of MARID-like, enriched subcontinental lithospheric mantle. We conclude that the spatial coincidence of the Kuusamo kimberlites and Dike 15 is likely the result of exploitation of similar trans-lithospheric corridors.
DS202007-1132
2020
Maas, R.Choi, F.M., Fiorentini, M.L., Giuliani, A., Foley, S.F., Maas, R., Taylor, W.R.Subduction related tetrogenesis of late Archean calc-alkaline lamprophyres in the Yilgarn craton ( Western Australia).Precambrian Research, Vol. 338, 105550Australialamprophyres

Abstract: We present a comprehensive petrographic, mineralogical and geochemical study of calc-alkaline lamprophyres (CAL) from the Archean Yilgarn Craton, Western Australia. Previous studies have shown that the emplacement age of CAL from the Eastern Goldfields Superterrane of the Yilgarn Craton is ~2684 to ~2640 Ma. A new Rb/Sr mica age for a CAL sample in the Western Yilgarn is ~2070 Ma. Both Archean and Proterozoic CAL analysed in this study display porphyritic textures and contain phenocrysts of amphibole, minor clinopyroxene and biotite in a fine-grained groundmass dominated by feldspar. High MgO, Ni and Cr abundances (up to 11.9 wt%, 373 and 993 ppm. respectively) are consistent with derivation of primitive magmas from a mantle source. Enrichment in H2O, reflected in the abundance of magmatic amphibole and mica, combined with high whole-rock LILE, Th/Yb ratios and negative Nb-Ta anomalies in trace element patterns are consistent with a source that was metasomatised by hydrous fluids analogous to those generated by Phanerozoic subduction-related processes. Chondritic ?Nd and ?Hf signatures and Archean mantle-like Sr isotope signatures of the Late Archean CAL indicate that the fluid metasomatism required to explain their volatile and trace-element enriched composition shortly preceded partial melting (i.e. there was insufficient time to develop enriched radiogenic isotopic signatures). The concurrence of apparently juvenile radiogenic isotopes and fluid-related trace element compositions requires a geodynamic scenario whereby dehydration of a subducted slab triggered metasomatism of the overlying mantle wedge. Our findings therefore support a subduction setting at ~2.6-2.7 Ga along the eastern margin of the Yilgarn Craton. The CAL from the Western Yilgarn have similar compositions but enriched Sr-Nd-Hf isotopes compared to those in the Eastern Goldfields Superterrane. This signature is consistent with melting of lithospheric mantle domains previously enriched by subduction-related metasomatism. Hence, our study suggests the presence of a subduction setting in the Western Yilgarn during the Archean, which is consistent with previous geodynamic reconstructions. However, the geodynamic trigger for the early Proterozoic event that generated CAL magmatism in the Western Yilgarn is currently unclear.
DS202007-1140
2020
Maas, R.Fitzpayne, A., Giuliani, A., Hergt, J., Woodhead, J.D., Maas, R.Isotopic analyses of clinopyroxene demonstrate the effects of mantle metasomatism upon the lithospheric mantle.Lithos, in press available, 77p. PdfAfrica, South Africadeposit - Kimberley

Abstract: The trace element and radiogenic isotope systematics of clinopyroxene have frequently been used to characterise mantle metasomatic processes, because it is the main host of most lithophile elements in the lithospheric mantle. To further our understanding of mantle metasomatism, both solution-mode Sr-Nd-Hf-Pb and in situ trace element and Sr isotopic data have been acquired for clinopyroxene grains from a suite of peridotite (lherzolites and wehrlites), MARID (Mica-Amphibole-Rutile-Ilmenite-Diopside), and PIC (Phlogopite-Ilmenite-Clinopyroxene) rocks from the Kimberley kimberlites (South Africa). The studied mantle samples can be divided into two groups on the basis of their clinopyroxene trace element compositions, and this subdivision is reinforced by their isotopic ratios. Type 1 clinopyroxene, which comprises PIC, wehrlite, and some sheared lherzolite samples, is characterised by low Sr (~100-200 ppm) and LREE concentrations, moderate HFSE contents (e.g., ~40-75 ppm Zr; La/Zr < 0.04), and restricted isotopic compositions (e.g., 87Sr/86Sri = 0.70369-0.70383; ?Ndi = +3.1 to +3.6) resembling those of their host kimberlite magmas. Available trace element partition coefficients can be used to show that Type 1 clinopyroxenes are close to being in equilibrium with kimberlite melt compositions, supporting a genetic link between kimberlites and these metasomatised lithologies. Thermobarometric estimates for Type 1 samples in this study indicate equilibration depths of 135-160 km within the lithosphere, thus showing that kimberlite melt metasomatism is prevalent in the deeper part of the lithosphere beneath Kimberley. In contrast, Type 2 clinopyroxenes occur in MARID rocks and coarse granular lherzolites in this study, which derive from shallower depths (<135 km), and have higher Sr (~350-1000 ppm) and LREE contents, corresponding to higher La/Zr of > ~ 0.05. The isotopic compositions of Type 2 clinopyroxenes are more variable and extend from compositions resembling the “enriched mantle” towards those of Type 1 rocks (e.g., ?Ndi = ?12.7 to ?4.4). To constrain the source of these variations, in situ Sr isotope analyses of clinopyroxene were undertaken, including zoned grains in Type 2 samples. MARID and lherzolite clinopyroxene cores display generally radiogenic but variable 87Sr/86Sri values (0.70526-0.71177), which are correlated with Sr contents and La/Zr ratios, and which might be explained by the interaction between peridotite and melts from different enriched sources within the lithospheric mantle. Most notably, the rims of these Type 2 clinopyroxenes trend towards compositions similar to those of the host kimberlite and Type 1 clinopyroxene from PIC and wehrlites. These results are interpreted to represent clinopyroxene overgrowth during late-stage (shortly before/during entrainment) metasomatism by kimberlite magmas. Our study shows that a pervasive, alkaline metasomatic event caused MARID to be generated and harzburgites to be converted to lherzolite in the lithospheric mantle beneath the Kimberley area, which was followed by kimberlite metasomatism during Cretaceous magmatism. This latter event is the time at which discrete PIC, wehrlite, and sheared lherzolite lithologies were formed, and MARID and granular lherzolites were partly modified.
DS202008-1380
2020
Maas, R.Choi, E., Fiorentini, M.L., Giuliani, A., Foley, S.F., Maas, R., Taylor, W.R.Subduction related petrogenesis of late Archean calc-alkaline lamprophyres in the Yilgarn craton, western Australia.Precambrian Research, Vol. 338, 105550, 18p. PdfAustralialamprophyres

Abstract: We present a comprehensive petrographic, mineralogical and geochemical study of calc-alkaline lamprophyres (CAL) from the Archean Yilgarn Craton, Western Australia. Previous studies have shown that the emplacement age of CAL from the Eastern Goldfields Superterrane of the Yilgarn Craton is ~2684 to ~2640 Ma. A new Rb/Sr mica age for a CAL sample in the Western Yilgarn is ~2070 Ma. Both Archean and Proterozoic CAL analysed in this study display porphyritic textures and contain phenocrysts of amphibole, minor clinopyroxene and biotite in a fine-grained groundmass dominated by feldspar. High MgO, Ni and Cr abundances (up to 11.9 wt%, 373 and 993 ppm. respectively) are consistent with derivation of primitive magmas from a mantle source. Enrichment in H2O, reflected in the abundance of magmatic amphibole and mica, combined with high whole-rock LILE, Th/Yb ratios and negative Nb-Ta anomalies in trace element patterns are consistent with a source that was metasomatised by hydrous fluids analogous to those generated by Phanerozoic subduction-related processes. Chondritic ?Nd and ?Hf signatures and Archean mantle-like Sr isotope signatures of the Late Archean CAL indicate that the fluid metasomatism required to explain their volatile and trace-element enriched composition shortly preceded partial melting (i.e. there was insufficient time to develop enriched radiogenic isotopic signatures). The concurrence of apparently juvenile radiogenic isotopes and fluid-related trace element compositions requires a geodynamic scenario whereby dehydration of a subducted slab triggered metasomatism of the overlying mantle wedge. Our findings therefore support a subduction setting at ~2.6-2.7 Ga along the eastern margin of the Yilgarn Craton. The CAL from the Western Yilgarn have similar compositions but enriched Sr-Nd-Hf isotopes compared to those in the Eastern Goldfields Superterrane. This signature is consistent with melting of lithospheric mantle domains previously enriched by subduction-related metasomatism. Hence, our study suggests the presence of a subduction setting in the Western Yilgarn during the Archean, which is consistent with previous geodynamic reconstructions. However, the geodynamic trigger for the early Proterozoic event that generated CAL magmatism in the Western Yilgarn is currently unclear.
DS202008-1383
2020
Maas, R.Dalton, H., Giuiani, A., Phillips, D., Hergt, J., Maas, R., Woodhead, J., Matchan, E., O'Brien, H.Kimberlite magmatism in Finland: distinct sources and links to the breakup of Rodinia.Goldschmidt 2020, 1p. AbstractEurope, Finlanddeposit - Kuusamo

Abstract: The Karelian Craton in Finland is host to (at least) two distinct pulses of kimberlite magmatism. Twenty kimberlite occurrences have so far been discovered on the southwest margin of the craton at Kaavi-Kuopio and seven kimberlites are located in the Kuusamo area within the core of the craton. Comprehensive radiometric age determinations (U-Pb, Ar- Ar and Rb-Sr) reveal that all kimberlite activity was restricted to the Proterozoic. The Kaavi-Kuopio field was emplaced over a protracted period from ~610 to 550 Ma and is predated by the Kuusamo cluster that represents a relatively short pulse of magmatism at ~750 to 730 Ma. The emplacement of kimberlites globally has recently been linked to supercontinent reorganisation and we propose a similar scenario for these Finnish occurrences which, at the time of kimberlite emplacement, were situated on the Baltica paleo-continent. This land mass was contiguous with Laurentia in the Proterozoic and together formed part of Rodinia. The breakup of Rodinia is considered to have commenced at ~750 Ma and initiation of the opening of the Iapetus ocean at ~615 Ma. Contemporaneous with Kaavi-Kuopio magmatism, this latter period of Neoproterozoic crustal extension also includes the emplacement of kimberlites and related rocks in areas that were linked with Baltica as part of Rodinia - West Greenland and eastern North America. Both the initial and final periods of Rodinia’s breakup have been linked to mantle upwellings from the core-mantle boundary. We suggest that kimberlite magmatism in Finland was promoted by the influx of heat from mantle upwellings and lithospheric extension associated with the demise of Rodinia. Although both magmatic episodes are potentially linked to the breakup of Rodinia, whole-rock and perovskite radiogenic isotope compositions for the Kuusamo kimberlites (?Nd(i) +2.6 to +3.3, ?Hf(i) +3.1 to +5.6) are distinct from the Kaavi-Kuopio kimberlites (?Nd(i) -0.7 to +1.8, ?Hf(i) -6.1 to +5.2). The spread in Hf isotope compositions for the Kaavi-Kuopio magmas may be linked to variable assimilation of diverse mantle lithologies.
DS202102-0188
2020
Maas, R.Fiorentini, M.L., O'Neill, C., Giuliani, A., Choi, E., Maas, R., Pirajno, F., Foley, S.Bushveld superplume drove Proterozoic magmatism and metallogenesis in Australia. Nature Scientific Reports, doi.org/10.1038/ s41598-020-76800-0 10p. PdfAustralia, Africa, South Africaalkaline magmatism

Abstract: Large-scale mantle convective processes are commonly reflected in the emplacement of Large Igneous Provinces (LIPs). These are high-volume, short-duration magmatic events consisting mainly of extensive flood basalts and their associated plumbing systems. One of the most voluminous LIPs in the geological record is the ~?2.06 billion-year-old Bushveld Igneous Complex of South Africa (BIC), one of the most mineralised magmatic complexes on Earth. Surprisingly, the known geographic envelope of magmatism related to the BIC is limited to a series of satellite intrusions in southern Africa and has not been traced further afield. This appears inconsistent with the inferred large size of the BIC event. Here, we present new radiometric ages for alkaline magmatism in the Archean Yilgarn Craton (Western Australia), which overlap the emplacement age of the BIC and indicate a much more extensive geographic footprint of the BIC magmatic event. To assess plume involvement at this distance, we present numerical simulations of mantle plume impingement at the base of the lithosphere, and constrain a relationship between the radial extent of volcanism versus time, excess temperature and plume size. These simulations suggest that the thermal influence of large plume events could extend for thousands of km within a few million years, and produce widespread alkaline magmatism, crustal extension potentially leading to continental break-up, and large ore deposits in distal sectors. Our results imply that superplumes may produce very extensive and diverse magmatic and metallogenic provinces, which may now be preserved in widely-dispersed continental blocks.
DS202106-0929
2021
Maas, R.Choi, E., Fiorentini, M.L., Giuliani, A., Foley, S.F., Maas, R., Graham, S.Petrogenesis of Proterozoic alkaline ultramafic rocks in the Yilgarn Craton, western Australia.Gondwana Research, Vol. 93, pp. 197-217. pdfAustraliacarbonatites

Abstract: The Yilgarn Craton and its northern margin contain a variety of petrogenetically poorly defined small-volume alkaline ultramafic rocks of Proterozoic age. This study documents the petrography, mineral and bulk-rock geochemistry and Nd-Hf-Sr-Pb isotope compositions of a selected suite of these rocks. They comprise ~2.03-2.06 Ga ultramafic lamprophyres (UML) and carbonatites from the Eastern Goldfields Superterrane (EGS), ~0.86 Ga UML from Norseman, and orangeites from the Earaheedy Basin, including samples from Jewill (~1.3 Ga), Bulljah (~1.4 Ga) and Nabberu (~1.8-1.9 Ga). The Proterozoic UML and carbonatites from the EGS and Norseman display very consistent chondritic to superchondritic Nd-Hf isotope compositions and trace-element ratios similar to modern OIBs, which are indicative of a common mantle source across this wide alkaline province. These Nd-Hf isotope compositions overlap with the evolution trends of global kimberlites through time, thus suggesting that this mantle source could be deep and ancient as that proposed for kimberlites. Conversely, the orangeites located in the Earaheedy Basin along the northern margin of the Yilgarn Craton display trace element signatures similar to subduction-related calc-alkaline magmas. Taken together with their highly enriched Sr-Nd-Hf isotope compositions, these characteristics indicate an ancient lithospheric mantle source, which was probably metasomatised by subduction-related fluids. As the ages of the Bulljah and Jewill orangeites overlap with the breakup of the Columbia supercontinent, it is proposed that orangeite magmatism was triggered by changes in plate stress conditions associated with this event. This study provides a comprehensive picture of the genesis of Proterozoic alkaline magmatism in the Yilgarn Craton, highlighting the complex tectono-magmatic evolution of this lithospheric block after its assembly in the Archean.
DS1996-0124
1996
Maasch, K.A.Berner, R.A., Maasch, K.A.Chemical weathering and controls on atmospheric O2 and CO2: fundamental principles were enunciated... 1845Geochimica et Cosmochimica Acta, Vol. 60, No. 9, May, pp. 1633-37GlobalChemical weather, supergene, laterites
DS1983-0424
1983
Maass, R.S.Maass, R.S.Early Proterozoic Tectonic Style in Central WisconsinGeological Society of America (GSA) MEMOIR., No. 160, PP. 85-96.WisconsinMid-continent
DS1996-0866
1996
Mabako, M.A.H.Mabako, M.A.H., Nakamura, E.neodymium and Strontium isotopic mapping of Archean Prot. boundary in southeast Tanzania using granites probes crustal growth.Precambrian Rseaerch, Vol.l 77, pp. 105-115.TanzaniaGeochronology, Tanzanian Craton
DS1975-0126
1975
Mabarak, C.D.Mabarak, C.D.Heavy Minerals in Late Tertiary Gravel and Recent Alluvial-colluvial Deposits in the Prairie Divide Region of Northern Larimer County, Colorado.Msc. Thesis, Colorado State University, 90P.Colorado, State Line, Rocky Mountains, United StatesProspecting, Kimberlite
DS1975-0337
1976
Mabarak, C.D.Mccallum, M.E., Mabarak, C.D.Diamond in Kimberlitic Diatremes of Northern ColoradoGeology, Vol. 4, PP. 467-469.United States, Colorado, State Line, Rocky MountainsKimberlite, State Line, Rocky Mountains
DS1975-0338
1976
Mabarak, C.D.Mccallum, M.E., Mabarak, C.D.Diamond in State Line Kimberlite Diatremes Albany County, Wyoming and Larimer County, Colorado.Wyoming Geological Survey Report Inv., No. 12, 36P.United States, Colorado, Wyoming, State Line, Rocky MountainsProspecting, Genesis, Distribution, Petrography, Mineralogy
DS1975-0339
1976
Mabarak, C.D.Mccallum, M.E., Mabarak, C.D.Diamond from Kimberlite Diatremes in Northern Colorado and Southern Wyoming.Geological Society of America (GSA), Vol. 8, No. 5, P. 609. (abstract.).United States, Colorado, Wyoming, State Line, Rocky MountainsBlank
DS1975-0565
1977
Mabarak, C.D.Mccallum, M.E., Mabarak, C.D., Coopersmith, H.G.Diamonds from Kimberlite in the Colorado Wyoming State Linedistrict.International Kimberlite Conference SECOND EXTENDED ABSTRACT VOLUME., United States, Colorado, Wyoming, State Line, Rocky MountainsBlank
DS1975-1137
1979
Mabarak, C.D.Mccallum, M.E., Mabarak, C.D., Coopersmith, H.G.Diamonds from Kimberlites in the Colorado Wyoming State Line District.International Kimberlite Conference SECOND Proceedings, Vol. 1, PP. 42-53.United States, Colorado, Wyoming, State Line, Rocky MountainsBlank
DS1950-0225
1955
Mabbutt, J.A.Mabbutt, J.A.Erosion Surfaces of Namaqualand and the Ages of Surface Deposits in the South Western Kalahari.Geological Survey of South Africa Transactions, Vol. 58, PP. 13-30.South AfricaGeomorphology
DS1989-0911
1989
Mabee, S.B.Mabee, S.B., Hardcastle, K.C., Wise, D.U.Ground truth?-relationship between lineaments and bedrock fabricGeological Society of America (GSA) Annual Meeting Abstracts, Vol. 21, No. 6, p. A68. AbstractGlobalTectonics, General - interest
DS200712-0663
2007
Mabidi, T.Mabidi, T., Thiart, C., De Wit, M.J.Secular changes recorded in mineralization in African crust.Journal of African Earth Sciences, Vol. 47, 2, Feb. pp. 88-94.AfricaMetallogeny - not specific to diamonds
DS200412-0711
2003
Maboko, M.Grantham, G.H., Maboko, M., Eglington, B.M.A review of the evolution of the Mozambique belt and implications for the amalgamation and dispersal of Rodinia and Gondwana.Proterozoic East Gondwana: Supercontinent assembly and Breakup. Ed. Yoshida , Geological Society of London Spe, No. 206, pp. 401-426.Gondwana, RodiniaPlume, tectonics
DS200612-0861
2006
Maboko, M.A.Manya, S., Kobayashi, K., Maboko, M.A., Nakamura, E.Ion microprobe zircon U Pb dating of the late Archean metavolcanics and associated granites of the Musoma Mara greenstone belt, northeast Tanzania: implicationsJournal of African Earth Sciences, Vol. 45, 3, pp. 355-366.Africa, TanzaniaCraton, geochronology, not specific to diamonds
DS1995-1133
1995
Maboko, M.A.H.Maboko, M.A.H.Neodynium isotope constraints on the protolith ages of rocks involved in Pan African tectonism Mozambique BeltJournal of the Geological Society of London, Vol. 152, No. 6, Nov. pp. 911-916TanzaniaGeochronology, Tectonics
DS1996-0867
1996
Maboko, M.A.H.Maboko, M.A.H., Nakamura, E.neodymium and Strontium isotopic mapping of the Archean Proterozoic boundary in southeastern Tanzania using granites ..Precambrian Research, Vol. 77, No. 1-2, March 1, pp. 105-116TanzaniaCrust, Geochronology
DS1997-0707
1997
Maboko, M.A.H.Maboko, M.A.H.P-T conditions of metamorphism in Wami River granulite complex, central coastal Tanzania: implicationsJournal of African Earth Sciences, Vol. 24, No. 1-2, Jan. 1, pp. 51-64TanzaniaGeotectonics, Mozambique Belt
DS2000-0603
2000
Maboko, M.A.H.Maboko, M.A.H.neodymium and Strontium isotopic investigation of the Archean - Proterozoic boundary in northeastern Tanzania:Precambrian Research, Vol. 102, No. 1-2, July 1, pp.87-98.TanzaniaTectonism - Neoproterozoic, Mozambique Belt
DS201212-0426
2012
Mabolani, S.Mabolani, S., Cawthorn, R.G., Reimold, W.U.Benfontein -02 kimberlite, northern Cape Province, South Africa.10th. International Kimberlite Conference Held Bangalore India Feb. 6-11, Poster abstractAfrica, South AfricaDeposit - Benfontein-02
DS2001-0710
2001
Mabolia, Y.Mabolia, Y.Congo ( Democratic Republic OF)Mining Annual Review, 3p.GlobalCountry - overview, economics, mining, Overview - brief
DS1998-0912
1998
Mabuza, M.Mabuza, M., Viljoen, K.S., Majola, S.New diamond bearing xenoliths from the Orapa mine, Botswana7th International Kimberlite Conference Abstract, pp. 521-23.BotswanaXenoliths, Deposit - Orapa
DS2003-0924
2003
Mabuza, M.B.Mdludlu, S., Mabuza, M.B., Tainton, K.M., Sweeney, R.J.A clinopyroxene thermobarometry traverse across Coromandel area, Brazil8 Ikc Www.venuewest.com/8ikc/program.htm, Session 9, POSTER abstractBrazilGeothermometry
DS200412-1285
2003
Mabuza, M.B.Mdludlu, S., Mabuza, M.B., Tainton, K.M., Sweeney, R.J.A clinopyroxene thermobarometry traverse across Coromandel area, Brazil.8 IKC Program, Session 9, POSTER abstractSouth America, BrazilCraton studies Geothermometry
DS200512-0667
2004
Mabuza, N.T.Mabuza, N.T., Pocock, J., Loveday, B.K.The use of surface active chemicals in heavy medium viscosity reduction.Minerals Engineering, Vol. 18, pp. 25-31.Africa, South AfricaDMS, magnetite, viscosity
DS201212-0091
2012
Mac Niocaill, C.Brown, R.J., Buisman, M.I., Fontana, G., Field, M., Mac Niocaill, C., Sparks, R.S.J., Stuart, F.M.Eruption of kimberlite magmas: physical volcanology, geomorphology and age of the youngest kimberlitic volcanoes known on Earth ( the Upper Pleistocene/Holocene Igwisi Hills volcanoes, Tanzania).Bulletin Volcanology, in press availableAfrica, TanzaniaDeposit - Igwisi
DS1920-0111
1922
Macadam, P.Macadam, P.Diamond Washing MachineryMining Engineering Journal of South Africa, Vol. 33, PT. 1, JUNE 3RD. P. 1325.South AfricaMining Engineering
DS1995-1693
1995
Macahdo, N.Scott, D.J., Macahdo, N.uranium-lead (U-Pb) (U-Pb) geochronology of the northern Torngat Orogen, Labrador: a record of Paleoproterozoic magmatismPrecambrian Research, Vol. 70, No. 3-4, Jan. pp. 169-190LabradorTectonics, Geochronology, Orogeny- Torngat
DS2000-0457
2000
Macambira, M.Jordt-Evangelista, H., Macambira, M., Peres. G.G., Limalead/lead single zircon dating of Paleoproterozoic calc-alkaline /alkaline magmatism in Sao Francisco...Igc 30th. Brasil, Aug. abstract only 1p.Brazil, Minas GeraisCraton - southeastern border, Geochronology
DS1994-0367
1994
Macambira, M.J.B.Dall'Agnol, R., Lafon, J-M., Macambira, M.J.B.Proterozoic anorogenic magmatism in the central Amazonian Province, Amazonian craton: geochronological, petrological and geochemical aspectsMineralogy and Petrology, Vo. 50, No. 1-3, pp. 113-138South AmericaGeochemistry, Petrology
DS200612-0845
2006
Macambira, M.J.B.Macambira, M.J.B., Armstrong, R.A., Silva, D.C.C., Camelo, J.F.The Archean Paleoproterozoic boundary in Amazonian Craton: new isotope evidence for crustal growth.Geochimica et Cosmochimica Acta, Vol. 70, 18, p. 2, abstract only.South America, BrazilGeochronology, craton
DS200712-0912
2007
Macambira, M.J.B.Rosset, A., De Min, A., Marques, L.S., Macambira, M.J.B., Ernesto, M., Renne, P.R., Piccrillo, E.M.Genesis and geodynamic significance of Mesoproterozoic and Early Cretaceous tholeiitic dyke swarms from the Sao Francisco Craton, Brazil.Journal of South American Earth Sciences, Vol. 24, 1, June pp. 69-92.South America, BrazilDyke swarms
DS200812-0023
2008
Macambira, M.J.B.Almeida, M.E., Macambira, M.J.B., Valente, S.de C.New geological and single zircon Pb evaporation dat a from the central Guyana Domain, southeastern Roraima, Brazil: tectonic implications for the central shield.Journal of South American Earth Sciences, Vol. 26, 3, Nov. pp. 318-328.South America, Brazil, GuyanaTectonics, Roraima
DS1993-0973
1993
MacArthur, B.T.Mars, P.J., MacArthur, B.T., Pirie, J.Canadian diamond exploration.. high risk.. high reward. Background-historical and overview of current northwest Territories play to date June 11, 1993.Bunting Warburg Inc. Research Report, June 11, 23p.Northwest TerritoriesNews item, Promotional overview
DS200812-0695
2008
MacauHubMacauHubAngola: industrial diamond mining continues to gain ground over the traditional sector.MacauHub, Dec. 1, 1p.Africa, AngolaNews item - production
DS200512-0151
2005
MacBride, L.Chakhmouradian, A.R., McCammon, C.A., MacBride, L., Cahill, C.L.Titaniferous garnets in carbonatites: their significance and place in the evolutionary history of host rocks.GAC Annual Meeting Halifax May 15-19, Abstract 1p.Classification - mineralogy
DS200812-0696
2008
MacBride, L.M.MacBride, L.M., Chakhmouradian, A.R.The petrology and geochemistry of kimberlite like rocks from the Konozero diatreme, Kola Peninsula, NW Russia.9IKC.com, 3p. extended abstractRussia, Kola Peninsula, Baltic ShieldCarbonatite
DS201012-0042
2009
Macc, R.A.Bauer, R., Macc, R.A.Laser inscription on diamonds.Australian Gemmologist, Vol. 23, 12, p.TechnologyDiamond Dias
DS201112-0628
2011
Maccaferri, F.Maccaferri, F., Bonafede, M., Rivalta, E.A quantitative study of the mechanisms governing dike propogation, dike arrest and sill formation.Journal of Volcanology and Geothermal Research, Vol. 208, 1-2, Nov. pp. 39-50.TechnologyGeodynamics of dikes and sills
DS200612-1182
2005
MacCarthy, J.K.Roy, M., MacCarthy, J.K., Selverstone, J.Upper mantle structure beneath eastern Colorado Plateau and Rio Grande rift revealed by Bouguer gravity, seismic velocities and xenolith data.Geochemistry, Geophysics, Geosystems: G3, Vol. 6, 10.1029/2005 GC001008United States, Colorado PlateauGeophysics - seismics
DS2001-1152
2001
Macchiato, M.Telesca, L., Cuomo, V., Lapenna, V., Macchiato, M.Statistical analysis of fractal properties of point processes modeling seismic sequencesPhysics of the Earth and Planetary Interiors, Vol. 125, No. 1-4, pp. 65-83.GlobalGeophysics - seismics, Experimental
DS1900-0204
1903
Macco, A.Macco, A.Review of Schmeisser's Vortrag " die Nutzbaren Bodenschaetze der Deutschen Schutzgebiete".Zeitschr. F. Prakt. Geol., Vol. 11, PP. 28-33; PP. 193-194.Africa, Namibia, ChinaMineral Resources, Diamond
DS1900-0340
1905
Macco, A.Macco, A.Sued afrikanische Diamanten #2Zeitschr. F. Prakt. Geol., Vol. 13, PP. 146-147.Africa, South AfricaGeology, Mineralogy, Premier
DS1900-0580
1907
Macco, A.Macco, A.Ueber die Sued afrikanischen Diamantlagerstatten: die Blau Ground Vorkommen in Suedafrika.Zeitschr. Deut. Geol. Ges., MONATSBER. Vol. 59, PP. 76-81. ALSO: Neues Jahrbuch f?r Mineralogie, BD.Africa, South AfricaGeology, Kimberlite Mines And Deposits
DS1990-1171
1990
MacDadyen, D.A.Pegg, C.C., Brummer, J.J., MacDadyen, D.A.Discovery of kimberlite diatremes in the Kirkland Lake area, Ontario #1The Canadian Institute of Mining, Metallurgy and Petroleum (CIM), The Canadian Institute of Mining, Metallurgy and Petroleum (CIM) Vol.89, No. 935, April p. 90. AbstractOntarioDiatremes -five, Diamondiferous tests
DS1920-0342
1927
Macdill, M.Macdill, M.American Diamonds. #5Literature Digest., Vol. 92, No. 9, PP. 23-24.United StatesBlank
DS1987-0761
1987
MacdonaldVan Schmus, W.R., Bickford, M.E., Lewry, Macdonalduranium-lead (U-Pb) geochronology in the Trans Hudson Orogen, northern SaskatchewanProg. in Phys. Geography, Vol. 24, pp. 407=24.SaskatchewanGeochronology
DS1910-0365
1913
Macdonald, A.Macdonald, A.In the Land of Pearl and GoldLondon: Fisher Unwin, 2nd. Edition., 319P.AustraliaKimberlite, Kimberley, Janlib, Travelogue
DS201212-0427
2012
Macdonald, A.Macdonald, A., Napier, S.Chemical and textural characterisation of non-kimberlitic chromian spinel populations from diamond exploration programs.10th. International Kimberlite Conference Held Bangalore India Feb. 6-11, Poster abstractAfrica, South Africa, Botswana, GabonDeposit - Malopo Farms
DS202205-0672
2022
Macdonald, A.Afonso, J., Ben-Mansour, W., O'Reilly, S.Y., Griffin, W.L., Salajeghegh, F., Foley, S., Begg, G., Selway, K., Macdonald, A., Januszczak, N., Fomin, I., Nyblade, A.A., Yang, Y.Thermochemical structure and evolution of cratonic lithosphere in central and southern Africa.Nature Geoscience, Apr. 26, 329p. FreeAfrica, South AfricaCraton

Abstract: The thermochemical structure of the subcontinental mantle holds information on its origin and evolution that can inform energy and mineral exploration strategies, natural hazard mitigation and evolutionary models of Earth. However, imaging the fine-scale thermochemical structure of continental lithosphere remains a major challenge. Here we combine multiple land and satellite datasets via thermodynamically constrained inversions to obtain a high-resolution thermochemical model of central and southern Africa. Results reveal diverse structures and compositions for cratons, indicating distinct evolutions and responses to geodynamic processes. While much of the Kaapvaal lithosphere retained its cratonic features, the western Angolan-Kasai Shield and the Rehoboth Block have lost their cratonic keels. The lithosphere of the Congo Craton has been affected by metasomatism, increasing its density and inducing its conspicuous low-topography, geoid and magnetic anomalies. Our results reconcile mantle structure with the causes and location of volcanism within and around the Tanzanian Craton, whereas the absence of volcanism towards the north is due to local asthenospheric downwellings, not to a previously proposed lithospheric root connecting with the Congo Craton. Our study offers improved integration of mantle structure, magmatism and the evolution and destruction of cratonic lithosphere, and lays the groundwork for future lithospheric evolutionary models and exploration frameworks for Earth and other terrestrial planets.
DS1989-0912
1989
MacDonald, A.J.MacDonald, A.J.The effect of the Canadian Exploration Incentive program on flow through share financingProspectors and Developers Association of Canada, 57th. Meeting, No. M-2, 15p. Database # 17922CanadaEconomics, Flow through
DS1996-1319
1996
MacDonald, D.Sinding, K., Poulin, R., MacDonald, D.Property rights for mineral resourcesJournal of Mineral Policy, Vol. 12, No. 1, pp. 24-29GlobalLegal, Mineral resources - property rights
DS1996-1320
1996
MacDonald, D.Sinding, K., Poulin, R., MacDonald, D.Property rights for mineral resources.... not specific to diamonds but ofinterest.Journal of Mineral Policy, Vol. 12, No. 1, pp. 24-29.GlobalLegal, Property rights
DS201602-0235
2015
Macdonald, D.I.M.Schiffer, C., Stephenson, R.A., Petersen, K.D., Nielsen, S.B., Jacobsen, B.H., Balling, N., Macdonald, D.I.M.A sub crustal piercing point for North Atlantic reconstructions and tectonic implications.Geology, Vol. 43, 12, pp. 1087-1090.Europe, GreenlandPlate Tectonics

Abstract: Plate tectonic reconstructions are usually constrained by the correlation of lineaments of surface geology and crustal structures. This procedure is, however, largely dependent on and complicated by assumptions on crustal structure and thinning and the identification of the continent-ocean transition. We identify two geophysically and geometrically similar upper mantle structures in the North Atlantic and suggest that these represent remnants of the same Caledonian collision event. The identification of this structural lineament provides a sub-crustal piercing point and hence a novel opportunity to tie plate tectonic reconstructions. Further, this structure coincides with the location of some major tectonic events of the North Atlantic post-orogenic evolution such as the occurrence of the Iceland Melt Anomaly and the separation of the Jan Mayen microcontinent. We suggest that this inherited orogenic structure played a major role in the control of North Atlantic tectonic processes.
DS1983-0425
1983
Macdonald, E.H.Macdonald, E.H.Alluvial Mining. #2London: Chapman And Hall, PP. 1, 25, 104-106, 115, 181, 135, 196, 320-321, 326-327, 339-340, 34GlobalAlluvial Mining Methods, Diamonds, Kimberlite
DS1983-0426
1983
Macdonald, E.H.Macdonald, E.H.Alluvial Mining. #1Methuen., 580P.GlobalKimberlite
DS201112-0629
2009
MacDonald, F.MacDonald, F.Control of rock strength on the initiation of kimberlite eruptions.Thesis, BASC University of British Columbia, MantleThesis - note availability based on request to author
DS2003-0855
2003
Macdonald, F.A.Macdonald, F.A., Bunting, J.A., Cina, S.E.Yarrabubba - a large deeply eroded impact structure in the Yilgarn Craton, WesternEarth and Planetary Science Letters, Vol. 213, No. 3-4, pp. 225-247.AustraliaImpact structure - not specific to diamonds
DS200412-1188
2003
Macdonald, F.A.Macdonald, F.A., Bunting, J.A., Cina, S.E.Yarrabubba - a large deeply eroded impact structure in the Yilgarn Craton, Western Australia.Earth and Planetary Science Letters, Vol. 213, no. 3-4, pp. 225-247.AustraliaImpact structure - not specific to diamonds
DS201201-0848
2011
Macdonald, F.A.Hoffman, P., Macdonald, F.A., Halverson, G.P.Chemical sediments association with Neoproterozoic glaciation: iron formation cap carbonate, barite and phosphorite.The Geological Record of Neoproterozoic glaciations, Memoirs 2011; Vol. 36, pp. 67-80GlobalGeomorphology - geochemistry
DS202006-0919
2020
Macdonald, F.A.Flowers, R.M., Macdonald, F.A., Siddoway, C.S., Havranek, R.Diachronous development of Great Unconformities before Neoproterozoic Snowlball Earth. Proceedinds of the National Academy of Sciences, Vol. 117, 19, 9p. PdfUnited States, Coloradogeothermometry

Abstract: The Great Unconformity marks a major gap in the continental geological record, separating Precambrian basement from Phanerozoic sedimentary rocks. However, the timing, magnitude, spatial heterogeneity, and causes of the erosional event(s) and/or depositional hiatus that lead to its development are unknown. We present field relationships from the 1.07-Ga Pikes Peak batholith in Colorado that constrain the position of Cryogenian and Cambrian paleosurfaces below the Great Unconformity. Tavakaiv sandstone injectites with an age of ?676 ± 26 Ma cut Pikes Peak granite. Injection of quartzose sediment in bulbous bodies indicates near-surface conditions during emplacement. Fractured, weathered wall rock around Tavakaiv bodies and intensely altered basement fragments within unweathered injectites imply still earlier regolith development. These observations provide evidence that the granite was exhumed and resided at the surface prior to sand injection, likely before the 717-Ma Sturtian glaciation for the climate appropriate for regolith formation over an extensive region of the paleolandscape. The 510-Ma Sawatch sandstone directly overlies Tavakaiv-injected Pikes granite and drapes over core stones in Pikes regolith, consistent with limited erosion between 717 and 510 Ma. Zircon (U-Th)/He dates for basement below the Great Unconformity are 975 to 46 Ma and are consistent with exhumation by 717 Ma. Our results provide evidence that most erosion below the Great Unconformity in Colorado occurred before the first Neoproterozoic Snowball Earth and therefore cannot be a product of glacial erosion. We propose that multiple Great Unconformities developed diachronously and represent regional tectonic features rather than a synchronous global phenomenon.
DS202107-1138
2021
Macdonald, F.A.Sturrock, C.P., Flowers, R.M., Macdonald, F.A.The late great unconformity of the central Canadian shield.Geochemistry, Geophysics, Geosytems, 49p. PdfCanada, Ontariogeochronology

Abstract: The Great Unconformity is a distinctive feature in the geologic record that separates more ancient rocks from younger (<540 Ma) sedimentary rocks. It commonly marks a substantial time gap in the rock record. When and why the Great Unconformity developed is much debated. We present new thermochronologic data that constrain when ancient rocks across the central Canadian Shield last cooled during exhumation to the surface before deposition of overlying sedimentary rocks that mark the Great Unconformity. These data and the geologic context indicate that the basement below the Great Unconformity erosion here was last exhumed after 650 Ma, in contrast to the pre-650 Ma timing inferred elsewhere in North America. This result is inconsistent with the notion that the Great Unconformity formed worldwide in a single erosion event.
DS202109-1472
2021
Macdonald, F.A.Hoffman, P.F., Halverson, G.P., Schrag, D.P., Higgins, J.A., Domack, E.W., Macdonald, F.A., Pruss, S.B., Blattler, C.L., Crockford, P.W., Hodgin, E.B., Bellefroid, E.J., Johnson, B.W., Hodgskiss, M.S.W., Lamothe, K.G., LoBianco, S.J.C., Busch, J.F., HowesSnowballs in Africa: sectioning a long-lived Neoproterozoic carbonate platform and its bathyal foreslope ( NW Namibia). (Octavi Group)Earth Science Reviews , Vol. 219, 103616 231p. PdfAfrica, NamibiaCraton - Congo

Abstract: Otavi Group is a 1.5-3.5-km-thick epicontinental marine carbonate succession of Neoproterozoic age, exposed in an 800-km-long Ediacaran?Cambrian fold belt that rims the SW cape of Congo craton in northern Namibia. Along its southern margin, a contiguous distally tapered foreslope carbonate wedge of the same age is called Swakop Group. Swakop Group also occurs on the western cratonic margin, where a crustal-scale thrust cuts out the facies transition to the platformal Otavi Group. Subsidence accommodating Otavi Group resulted from S?N crustal stretching (770-655?Ma), followed by post-rift thermal subsidence (655-600?Ma). Rifting under southern Swakop Group continued until 650-635?Ma, culminating with breakup and a S-facing continental margin. No hint of a western margin is evident in Otavi Group, suggesting a transform margin to the west, kinematically consistent with S?N plate divergence. Rift-related peralkaline igneous activity in southern Swakop Group occurred around 760 and 746?Ma, with several rift-related igneous centres undated. By comparison, western Swakop Group is impoverished in rift-related igneous rocks. Despite low paleoelevation and paleolatitude, Otavi and Swakop groups are everywhere imprinted by early and late Cryogenian glaciations, enabling unequivocal stratigraphic division into five epochs (period divisions): (1) non-glacial late Tonian, 770-717?Ma; (2) glacial early Cryogenian/Sturtian, 717-661?Ma; (3) non-glacial middle Cryogenian, 661-646?±?5?Ma; (4) glacial late Cryogenian/Marinoan, 646?±?5-635?Ma; and (5) non-glacial early Ediacaran, 635-600?±?5?Ma. Odd numbered epochs lack evident glacioeustatic fluctuation; even numbered ones were the Sturtian and Marinoan snowball Earths. This study aimed to deconstruct the carbonate succession for insights on the nature of Cryogenian glaciations. It focuses on the well-exposed southwestern apex of the arcuate fold belt, incorporating 585?measured sections (totaling >190?km of strata) and?>?8764 pairs of ?13C/?18Ocarb analyses (tabulated in Supplementary On-line Information). Each glaciation began and ended abruptly, and each was followed by anomalously thick ‘catch-up’ depositional sequences that filled accommodation space created by synglacial tectonic subsidence accompanied by very low average rates of sediment accumulation. Net subsidence was 38% larger on average for the younger glaciation, despite its 3.5-9.3-times shorter duration. Average accumulation rates were subequal, 4.0 vs 3.3-8.8?m Myr?1, despite syn-rift tectonics and topography during Sturtian glaciation, versus passive-margin subsidence during Marinoan. Sturtian deposits everywhere overlie an erosional disconformity or unconformity, with depocenters ?1.6?km thick localized in subglacial rift basins, glacially carved bedrock troughs and moraine-like buildups. Sturtian deposits are dominated by massive diamictite, and the associated fine-grained laminated sediments appear to be local subglacial meltwater deposits, including a deep subglacial rift basin. No marine ice-grounding line is required in the 110 Sturtian measured sections in our survey. In contrast, the newly-opened southern foreslope was occupied by a Marinoan marine ice grounding zone, which became the dominant repository for glacial debris eroded from the upper foreslope and broad shallow troughs on the Otavi Group platform, which was glaciated but left nearly devoid of glacial deposits. On the distal foreslope, a distinct glacioeustatic falling-stand carbonate wedge is truncated upslope by a glacial disconformity that underlies the main lowstand grounding-zone wedge, which includes a proximal 0.60-km-high grounding-line moraine. Marinoan deposits are recessional overall, since all but the most distal overlie a glacial disconformity. The Marinoan glacial record is that of an early ice maximum and subsequent slow recession and aggradation, due to tectonic subsidence. Terminal deglaciation is recorded by a ferruginous drape of stratified diamictite, choked with ice-rafted debris, abruptly followed by a syndeglacial-postglacial cap-carbonate depositional sequence. Unlike its Sturtian counterpart, the post-Marinoan sequence has a well-developed basal transgressive (i.e., deepening-upward) cap dolomite (16.9?m regional average thickness, n?=?140) with idiosyncratic sedimentary features including sheet-crack marine cements, tubestone stromatolites and giant wave ripples. The overlying deeper-water calci-rhythmite includes crystal-fans of former aragonite benthic cement ?90?m thick, localized in areas of steep sea-floor topography. Marinoan sequence stratigraphy is laid out over ?0.6?km of paleobathymetric relief. Late Tonian shallow-neritic ?13Ccarb records were obtained from the 0.4-km-thick Devede Fm (~770-760?Ma) in Otavi Group and the 0.7-km-thick Ugab Subgroup (~737-717?Ma) in Swakop Group. Devede Fm is isotopically heavy, +4-8‰ VPDB, and could be correlative with Backlundtoppen Fm (NE Svalbard). Ugab Subgroup post-dates 746?Ma volcanics and shows two negative excursions bridged by heavy ?13C values. The negative excursions could be correlative with Russøya and Garvellach CIEs (carbon isotope excursions) in NE Laurentia. Middle Cryogenian neritic ?13C records from Otavi Group inner platform feature two heavy plateaus bracketed by three negative excursions, correlated with Twitya (NW Canada), Taishir (Mongolia) and Trezona (South Australia) CIEs. The same pattern is observed in carbonate turbidites in distal Swakop Group, with the sub-Marinoan falling-stand wedge hosting the Trezona CIE recovery. Proximal Swakop Group strata equivalent to Taishir CIE and its subsequent heavy plateau are shifted bidirectionally to uniform values of +3.0-3.5‰. Early Ediacaran neritic ?13C records from Otavi Group inner platform display a deep negative excursion associated with the post-Marinoan depositional sequence and heavy values (??+?11‰) with extreme point-to-point variability (?10‰) in the youngest Otavi Group formation. Distal Swakop Group mimics older parts of the early Ediacaran inner platform ?13C records, but after the post-Marinoan negative excursion, proximal Swakop Group values are shifted bidirectionally to +0.9?±?1.5‰. Destruction of positive and negative CIEs in proximal Swakop Group is tentatively attributed to early seawater-buffered diagenesis (dolomitization), driven by geothermal porewater convection that sucks seawater into the proximal foreslope of the platform. This hypothesis provocatively implies that CIEs originating in epi-platform waters and shed far downslope as turbidites are decoupled from open-ocean DIC (dissolved inorganic carbon), which is recorded by the altered proximal Swakop Group values closer to DIC of modern seawater. Carbonate sedimentation ended when the cratonic margins collided with and were overridden by the Atlantic coast-normal Northern Damara and coast-parallel Kaoko orogens at 0.60-0.58?Ga. A forebulge disconformity separates Otavi/Swakop Group from overlying foredeep clastics. In the cratonic cusp, where the orogens meet at a right angle, the forebulge disconformity has an astounding ?1.85?km of megakarstic relief, and km-thick mass slides were displaced gravitationally toward both trenches, prior to orogenic shortening responsible for the craton-rimming fold belt.
DS202109-1491
2021
Macdonald, F.A.Sturrock, C.P., Flowers, R.M., Macdonald, F.A.The Late unconformity of the central Canadian Shield.Geochemistry, Geophysics, Geosystems, Vol. 22, e2020GC009567Canada, Saskatchewancraton

Abstract: The Great Unconformity is a distinctive feature in the geologic record that separates more ancient rocks from younger (<540 Ma) sedimentary rocks. It commonly marks a substantial time gap in the rock record. When and why the Great Unconformity developed is much debated. We present new thermochronologic data that constrain when ancient rocks across the central Canadian Shield last cooled during exhumation to the surface before deposition of overlying sedimentary rocks that mark the Great Unconformity. These data and the geologic context indicate that the basement below the Great Unconformity erosion here was last exhumed after 650 Ma, in contrast to the pre-650 Ma timing inferred elsewhere in North America. This result is inconsistent with the notion that the Great Unconformity formed worldwide in a single erosion event.
DS2001-0711
2001
Macdonald, G.Macdonald, G., Wytrychowski, S., Baker, Madsen, E.Environmental management and monitoring - Diavik 2001 dike contruction29th. Yellowknife Geoscience Forum, Nov. 21-23, abstract p. 55-6.Northwest TerritoriesLegal - environment, Deposit - Diavik
DS1994-0166
1994
Macdonald, I.Bizzi, L.A., Smith, C.B., De Wit, M., Macdonald, I., Armstrong, R.A.Isotopic characteristics of the lithospheric mantle underlying the southwest Sao Francisco craton margin, Brasil.International Symposium Upper Mantle, Aug. 14-19, 1994, pp. 227-255.BrazilGeochronology, Craton
DS201812-2885
2018
Macdonald, I.Smith, C.B., Atkinson, W.J., Tyler, E.W.J., Hall, A.E., Macdonald, I.Argyle deposit: The discovery of the Argyle pipe, western Australia: the world's first lamproite-hosted diamond mine.Society of Economic Geology Geoscience and Exploration of the Argyle, Bunder, Diavik, and Murowa Diamond Deposits, Special Publication no. 20, pp. 49-64.Australia, western Australiadeposit - Argyle
DS201312-0562
2013
Macdonald, J.Macdonald, J.Zircon - Earth's timekeeper.Geology Today, Vol. 29, 3, 2p.TechnologyGeochronology
DS1910-0366
1913
Macdonald, J.A.Macdonald, J.A.Diamonds in British Columbia; February, 1913Min. Sci. Press, Feb. 8TH. P. 247. FEBRUARYCanada, British ColumbiaHistory
DS1987-0615
1987
Macdonald, K.A.Rockwell, M.C., Macdonald, K.A.Processing technology for the recovery of placer mineralsMarine Mining, Vol. 6, No. 2, pp. 161-175GlobalGravity Seperation techniques, placer mining, Mining Methods
DS1989-0913
1989
Macdonald, K.C.Macdonald, K.C.Propagating rifts exposedNature, Vol. 342, Dec. 14, pp. 640-741GlobalTectonics, Rifts
DS1989-0914
1989
Macdonald, K.C.Macdonald, K.C.Propogating rifts exposedNature, Vol. 342, Dec. 14, pp. 740-1.GlobalTectonics, sea floor spreading
DS1990-0965
1990
Macdonald, K.C.Macdonald, K.C.A slow but restless ridgeNature, Vol. 348, Nov. 8, pp. 108-9.MantleTectonics, sea floor spreading
DS1990-0966
1990
Macdonald, K.C.Macdonald, K.C., Fox, P.J.The mid-ocean ridgeOcean Resources NL., Trans Hex International Ltd., Vol. 262, No. 6, June pp. 72-95Ocean RidgeTectonics, Plate tectonics
DS1991-1028
1991
Macdonald, K.C.Macdonald, K.C., Scheirer, D.S., Carbote, S.M.Mid-ocean ridges: discontinuities, segments and giant cracksScience, Vol. 253, August 30, pp. 986-994GlobalTectonics, Mid-ocean ridges
DS1993-0944
1993
Macdonald, K.C.Macdonald, K.C., Fox, P.J.It's only topography: part 2Gsa Today, Vol. 3, No. 2, February pp. 29, 30, 31, 34, 35GlobalOverview, Topography -computers
DS1993-0945
1993
Macdonald, K.C.Macdonald, K.C., Scheirer, D.S., Carbotte, S.It's only topography: part 1Gsa Today, Vol. 3, No. 1, January p. 1, 24, 25GlobalSonar mapping systems, Ridges, offsets, tectonics, structure
DS1960-0814
1967
Macdonald, R.Cox, K.G., Macdonald, R., Hornung, G.Geochemical and Petrographic Provinces in the Karroo Basalts of Southern Africa.American MINERALOGIST., Vol. 52, PP. 1451-1474.South AfricaPetrography, Geochemistry, Related Rocks
DS1985-0403
1985
Macdonald, R.Macdonald, R.Quaternary Peralkaline Silicic Rocks and Caldera Volcanoes Of Kenya.Conference Report of A Meeting of The Volcanic Studies Group, 1P. ABSTRACT.Central Africa, KenyaGeochemistry
DS1985-0404
1985
Macdonald, R.Macdonald, R., Thorpe, R.S., Gaskarth, J.W., Grinrod, A.R.Multi-component Origin of Caledonian Lamprophyres of Northern England.Mineralogical Magazine., Vol. 49, No. 353 PT. 4 SEPTEMBER PP. 485-494.GlobalLamprophyres
DS1990-0552
1990
Macdonald, R.Gent, M.R., Harper, C.T., Guliov, P., Macdonald, R.Saskatchewan diamonds: a new realityThe Canadian Mining and Metallurgical Bulletin (CIM Bulletin), Vol. 83, No. 939, July p. 115. Abstract (PDA)SaskatchewanBrief overview, Diamond activities
DS1992-0970
1992
Macdonald, R.Macdonald, R., Upton, B.G.J., Collerson, K.D., Hearn, B.C.Potassic mafic lavas of the Bearpaw Mountains, Montana-mineralogy, chemistry and origin ( review)Journal of Petrology, Vol. 33, No. 2, April pp. 305-346MontanaPotassic magmatism, Bearpaw Mountains
DS1993-0272
1993
MacDonald, R.Collerson, K.D., Scherer, E.E., MacDonald, R.The evolution of Wyoming craton lower crust: uranium-lead (U-Pb) (U-Pb) shrimp and neodymium-Sr isotopic evidence for middle Archean and Early Proterozoic events.The Xenolith window into the lower crust, abstract volume and workshop, p. 4.MontanaCraton
DS1994-1076
1994
Macdonald, R.Macdonald, R., Williams, L.A., Gass, I.G.Tectonomagmatic evolution of Kenya rift valley -some geologicalperspectives.Journal of the Geological Society of London, Vol. 151, No. 5, Sept. pp. 879-888.KenyaTectonics, Rifting
DS1998-0130
1998
Macdonald, R.Black, S., Macdonald, R., Barreiro, Dunkley, SmithOpen system alkaline magmatism in northern Kenya: evidence from U seriesdisequilibration temperatures and radiogenic...Contributions to Mineralogy and Petrology, Vol. 131, No. 4, May pp. 364-378.KenyaGeochronology - isotopes, Alkaline rocks
DS2001-0712
2001
Macdonald, R.Macdonald, R., Rogers, N., Fitton, J.G., Black, SmithPlume lithosphere interactions in the generation of the basalts of the Kenya rift, east Africa.Journal of Petrology, Vol. 42, No. 5, pp. 877-900.East Africa, KenyaTectonics - plume, mantle
DS200412-0477
2004
Macdonald, R.Downes, H., Macdonald, R., Upton, B.G.J., Cox, K.G., Bodinier, J-L., Mason, P.R.D., James, D., Hill, P.G., HeaUltramafic xenoliths from the Bearpaw Mountains, Montana: USA: evidence for multiple metasomatic events in the lithospheric mantJournal of Petrology, Vol. 45, 8, pp. 1631-1662.United States, MontanaMetasomatism
DS200612-0846
2006
Macdonald, R.Macdonald, R., Scaillet, B.The central Kenya peralkaline province: insights into the evolution of peralkaline salic magmas.Lithos, in press availableAfrica, KenyaMagmatism - not specific to alkaline rocks
DS201112-0630
2011
Macdonald, R.Macdonald, R.Evolution of peralkaline silicic complexes: lessons from the extrusive rocks.Peralk-Carb 2011, workshop held Tubingen Germany June 16-18, AbstractMelting
DS201212-0428
2012
Macdonald, R.Macdonald, R.Evolution of peralkaline silicic complexes: lessons from the extrusive rocks. ( caldera collapse)Lithos, Vol. 152, pp. 11-12.MantlePre-eruption chambers
DS201312-0928
2013
Macdonald, R.Upton, B.G.J., Macdonald, R., Odling, N., Ramo, O.T., Baginski, B.Kungnaat, revisited. A review of five decades of research into an alkaline complex in South Greenland, with new trace element and Nd isotopic data.Mineralogical Magazine, Vol. 77, 4, pp. 523-550.Europe, GreenlandKungnaat
DS201705-0851
2017
Macdonald, R.Macdonald, R., Baginski, B., Zozulya, D.Differing responses of zircon, chevkinite - (Ce), monazite-(Ce) and fergusonite-(Y) to hydrothermal alteration: Evidence from the Keivy alkaline province, Kola Peninsula.Mineralogy and Petrology, in press available 22p.Russia, Kola PeninsulaAlkaline rocks

Abstract: A quartzolite from the Rova occurrence, Keivy alkali granite province, Kola Peninsula, Russia, is used to examine the differing responses of certain rare-metal minerals during interaction with hydrothermal fluids. The minerals are two silicates [chevkinite-(Ce) and zircon], a phosphate [monazite-(Ce)] and an oxide [fergusonite-(Y)]. Textural evidence is taken to show that the dominant alteration mechanism was interface-coupled dissolution-reprecipitation. Zircon was the most pervasively altered, possibly by broadening of cleavage planes or fractures; the other minerals were altered mainly on their rims and along cracks. The importance of cracks in promoting fluid access is stressed. The compositional effects of the alteration of each phase are documented. The hydrothermal fluids carried few ligands capable of transporting significant amounts of rare-earth elements (REE), high field strength elements (HFSE) and actinides; alteration is inferred to have been promoted by mildly alkaline, Ca-bearing fluids. Expansion cracks emanating from fergusonite-(Y) are filled with unidentified material containing up to 35 wt% UO2 and 25 wt% REE2O3, indicating late-stage, short-distance mobility of these elements. Electron microprobe chemical dating of monazite yielded an age of 1665 ± 22 Ma, much younger than the formation age of the Keivy province (2.65-2.67 Ga) but comparable to that of the Svecofennian metamorphic event which affected the area (1.9-1.7 Ga) or during fluid-thermal activation of the region during rapakivi granite magmatism (1.66-1.56 Ga). Dates for altered monazite range from 2592 ± 244 Ma to 773 ± 88 Ma and reflect disturbance of the U-Th-Pb system during alteration.
DS201709-2038
2017
Macdonald, R.Nasdala, L., Broska, I., Harlov, D.E., Macdonald, R.Recent progress in the study of accessory minerals. Outline of special volume.Mineralogy and Petrology, Vol. 111, 4, pp. 431-433.Technologymineralogy

Abstract: Accessory minerals are a common species in igneous and metamorphic rocks that are not considered characteristic of the host rock and hence do not affect its root name. Accessories tend to be complex in terms of their chemical and isotopic composition and their structural state. In spite of not being major rock constituents, they are, however, of enormous petrologic interest as they contain a record of the formation and post-formation history of their host rock. The study of accessory minerals hence has increased continuously during the past years, and still increases (Fig. 1). Recent progress is driven by new analytical opportunities of (in situ) micro-techniques. More and more the internal textures, that is, elemental, isotopic, and/or structural distribution patterns within individual grains, have come into the focus of researchers; a few examples are compiled in Fig. 2.
DS1988-0136
1988
Macdonald, R.A.Collerson, K., Hearm, B.C., Macdonald, R.A., Upton, B.F., Park, J.G.Granulite xenoliths from the Bearpaw Mountains,Montana: constraints on the character and evolution of lower continental crustTerra Cognita, Eclogite conference, Vol. 8, No. 3, Summer, p. 270. AbstractMontanaXenoliths, Bearpaw Mountains
DS1989-0279
1989
MacDonald, R.A.Collerson, K.D., MacDonald, R.A., Upton, B.G.J., Harmon, R.S.Composition and evolution of lower continental crust:evidence from xenoliths in Eocene lavas from the Bearpaw Mountains, MontanaNew Mexico Bureau of Mines Bulletin., Continental Magmatism Abstract Volume, Held, Bulletin. No. 131, p. 57. AbstractMontanaXenoliths
DS1989-0608
1989
MacDonald, R.A.Hearn, B.C.Jr., Collerson, K.D., MacDonald, R.A., Upton, B.G.J.Mantle crustal lithosphere of north central Montana,USA: evidence fromxenolithsNew Mexico Bureau of Mines Bulletin., Continental Magmatism Abstract Volume, Held, Bulletin. No. 131, p. 125. AbstractMontanaXenoliths
DS1991-0694
1991
Macdonald, R.A.Hearn, B.C.Jr., Collerson, K.D., Upton, B.G.J., Macdonald, R.A.Ancient enriched upper mantle beneath north-central Montana: evidence fromxenolithsGuidebook of the Central Montana Alkalic Province, ed. Baker, D.W., Berg. R., No. 100, pp. 133-135. extended abstractMontanaMantle, xenoliths
DS1994-1320
1994
Macdougall, D.Otto, J., Macdougall, D.Project financing and the mineral development agreementTransactions of the Institute of Mining and Metallurgy (IMM), Vol. 103, A, pp. A117-123GlobalLegal, mining law, Project agreements
DS1995-1134
1995
MacDougall, D.G.MacDougall, D.G.Rare element occurrencesGeological Survey of Canada (GSC) Open File, No. 3119, pp. 67-76.SaskatchewanCarbonatite
DS1986-0511
1986
Macdougall, J.D.Macdougall, J.D., Lugmair, G.W.Strontium and neodymium isotopes in basalts from the East Pacific Rise-significance for mantle heterogeneityEarth and Planetary Science Letters, Vol. 77, No. 3-4, April pp. 273-284East Pacific RiseGeochronology
DS1988-0586
1988
Macdougall, J.D.Rubin, K.H., Macdougall, J.D.226 Ra excesses in mid ocean ridge basalts and mantle meltingNature, Vol. 335, September 8, pp. 158-161. Database # 17368GlobalMantle, Genesis
DS1992-0356
1992
Macdougall, J.D.Deng, F-L, Macdougall, J.D.Proterozoic depletion of the lithosphere recorded in mantle xenoliths from Inner MongoliaNature, Vol. 360, No. 6402, November 26, pp. 333-335GlobalXenoliths
DS1997-0641
1997
Macdougall, J.D.Kumar, A., Charan, S.N., Gopalan, K., Macdougall, J.D.Isotope evidence for a long lived source for Proterozoic carbonatites from South India.Geological Association of Canada (GAC) Abstracts, India, southCarbonatite, Proterozoic, geochronology
DS1998-0817
1998
Macdougall, J.D.Kumar, A., Charan, N., Gopalan, K., Macdougall, J.D.A long lived enriched mantle source for two Proterozoic carbonatite complexes from Tamil Nadu, southern India.Geochimica et Cosmochimica Acta, Vol. 62, No. 3, Feb. pp. 515-523.IndiaCarbonatite, Hogenakal, Sevathur, geochronology
DS1999-0431
1999
Macdougall, J.D.Macdougall, J.D., Haggerty, S.E.Ultradeep xenoliths from African kimberlites: Strontium and neodymium isotopic compositions suggest complex history.Earth and Planetary Science Letters, Vol. 170, No. 1-2, June 30, pp. 73-82.South Africa, Africa, Liberia, Sierra LeoneGeochronology
DS2000-0534
2000
MacDougall, J.D.Krishnamurthy, P., Gopalan, K., MacDougall, J.D.Olivine compositions in picrite basalts and the Deccan volcanic cycleJournal of Petrology, Vol. 41, No. 7, July, pp. 1057-70.IndiaPicrites
DS201710-2242
2017
MacDougall, J.G.MacDougall, J.G., Jadamec, M.A., Fischer, K.M.The zone of influence of the subducting slab in the asthenospheric mantle.Journal of Geophysical Research: Solid Earth, Vol. 122, 8, pp. 6599-6624.Mantlesubduction

Abstract: Due to the multidisciplinary nature of combined geodynamics and shear wave splitting studies, there is still much to be understood in terms of isolating the contributions from mantle dynamics to the shear wave splitting signal, even in a two-dimensional (2-D) mantle flow framework. This paper investigates the viscous flow, lattice preferred orientation (LPO) development, and predicted shear wave splitting for a suite of buoyancy-driven subduction models using a non-linear rheology to shed light on the nature of the slab-driven asthenospheric flow and plate-mantle coupling. The slab-driven zone of influence in the mantle, LPO fabric, and resulting synthetic splitting are sensitive to slab strength and slab initial slab dip. The non-linear viscosity formulations leads to dynamic reductions in asthenospheric viscosity extending over 600 km into the mantle wedge and over 300 km behind the trench, with peak flow velocities occurring in models with a weaker slab and moderate slab dip. The olivine LPO fabric in the asthenosphere generally increases in alignment strength with increased proximity to the slab but can be transient and spatially variable on small length scales. The results suggest that LPO formed during initial subduction may persist into the steady state subduction regime. Vertical flow fields in the asthenosphere can produce shear wave splitting variations with back azimuth that deviate from the predictions of uniform trench-normal anisotropy, a result that bears on the interpretation of complexity in shear wave splitting observed in real subduction zones. Furthermore, the models demonstrate the corner flow paradigm should not be equated with a 2-D subduction framework.
DS1990-0967
1990
MacDougall, R.E.MacDougall, R.E., Fuchs, R.L.Property sales- getting from here to thereAmerican Institute of Mining, Metallurgical, and Petroleum Engineers (AIME) Preprint, No. 90-36, 5pGlobalLaw, Mineral properties -overview
DS1997-0098
1997
Mace, J.Bernard-Griffiths, J., Gruau, G., Mace, J.Continental lithospheric contribution to alkaline magmatism: isotopic Sr, lead) and geochemical rare earth elements (REE).Journal of Petrology, Vol. 38, No. 1, Jan. 1, pp. 115-132.MantleSerra de Monchique, Mount Ormonde, Alkaline rocks
DS1994-1077
1994
MacEachren, A.M.MacEachren, A.M., Taylor, D.R.T.Visualization in modern cartographyElsevier, 345p. $ 45.00 United StatesGlobalBook -ad, Cartography
DS1997-0708
1997
MacEachren, A.M.MacEachren, A.M.How maps work... representation, visualization and designEarth Observation Magazine books, $ 50.00GlobalBook - ad, Maps
DS2000-0027
2000
MacedoArchanjo, C.J., Trinidade, R.I., Macedo, AraujoMagnetic fabric of a basaltic dyke swarm associated with Mesozoic rifting in northeastern Brasil.Journal of South American Earth Sciences, Vol. 13, No. 3, July pp. 179-89.BrazilDike swarms, tectonics, Geophysics - magnetics
DS1992-0113
1992
Macedo, M.H.F.Bellieni, G., Macedo, M.H.F., Petrini, R., Piccirillo, E.M.Evidence of magmatic activity related to Middle Jurassic and LowerChemical Geology, Vol. 97, No. 1/2, May 15, pp. 9-32BrazilTectonics, Geochronology
DS200912-0130
2009
Macedonio, G.Costa, A., Sparks, R.J.S., Macedonio, G., melnik, O.Effects of wall rock elasticity on magma flow in dykes during explosive eruptions.Earth and Planetary Science Letters, Vol. 288, 3-4, pp. 455-462.MantleMagmatism - not specific to diamonds
DS202012-2209
2020
Macedonio, G.Buono, G., Fanara, S., Macedonio, G., Palladino, D.M., Petrosino, P., Sottili, G., Pappalardo, L.Dynamics of degassing in evolved alkaline magmas: petrological, experimental and theoretical insights.Earth-Science Reviews, Vol. 211, 103402, 23p. PdfMantlealkaline

Abstract: In the last few decades, advanced monitoring networks have been extended to the main active volcanoes, providing warnings for variations in volcano dynamics. However, one of the main tasks of modern volcanology is the correct interpretation of surface-monitored signals in terms of magma transfer through the Earth's crust. In this frame, it is crucial to investigate decompression-induced magma degassing as it controls magma ascent towards the surface and, in case of eruption, the eruptive style and the atmospheric dispersal of tephra and gases. Understanding the degassing behaviour is particularly intriguing in the case of poorly explored evolved alkaline magmas. In fact, these melts frequently feed hazardous, highly explosive volcanoes (e.g., Campi Flegrei, Somma-Vesuvius, Colli Albani, Tambora, Azores and Canary Islands), despite their low viscosity that usually promotes effusive and/or weakly explosive eruptions. Decompression experiments, together with numerical models, are powerful tools to examine magma degassing behaviour and constrain field observations from natural eruptive products and monitoring signals. These approaches have been recently applied to evolved alkaline melts, yet numerous open questions remain. To cast new light on the degassing dynamics of evolved alkaline magmas, in this study we present new results from decompression experiments, as well as a critical review of previous experimental works. We achieved a comprehensive dataset of key petrological parameters (i.e., 3D textural data for bubbles and microlites using X-ray computed microtomography, glass volatile contents and nanolite occurrence) from experimental samples obtained through high temperature-high pressure isothermal decompression experiments on trachytic alkaline melts at super-liquidus temperature. We explored systematically a range of final pressures (from 200 to 25 MPa), decompression rates (from 0.01 to 1 MPa s?1), and volatile (H2O and CO2) contents. On these grounds, we integrated coherently literature data from decompression experiments on evolved alkaline (trachytic and phonolitic) melts under various conditions, with the aim to fully constrain the degassing mechanisms and timescales in these magmas. Finally, we simulated numerically the experimental conditions to evaluate strengths and weaknesses in decrypting degassing behaviour from field observations. Our results highlight that bubble formation in evolved alkaline melts is primarily controlled by the initial volatile (H2O and CO2) content during magma storage. In these melts, bubble nucleation needs low supersaturation pressures (? 50-112 MPa for homogeneous nucleation, ? 13-25 MPa for heterogeneous nucleation), resulting in high bubble number density (~ 1012-1016 m?3), efficient volatile exsolution and thus in severe rheological changes. Moreover, the bubble number density is amplified in CO2-rich melts (mole fraction XCO2 ? 0.5), in which continuous bubble nucleation predominates on growth. These conditions typically lead to highly explosive eruptions. However, moving towards slower decompression rates (? 10?1 MPa s?1) and H2O-rich melts, permeable outgassing and inertial fragmentation occur, promoting weakly explosive eruptions. Finally, our findings suggest that the exhaustion of CO2 at deep levels, and the consequent transition to a H2O-dominated degassing, can crucially enhance magma vesiculation and ascent. In a hazard perspective, these constraints allow to postulate that time-depth variations of unrest signals could be significantly weaker/shorter (e.g., minor gas emissions and short-term seismicity) during major eruptions than in small-scale events.
DS202109-1455
2021
Macedonio, G.Buono, G., Fanara, S., Macedonio, G., Palladino, D.M., Petrosino, P., Sottili, G., Pappalardo, L.Dynamics of degassing in evolved alkaline magmas: petrological, experimental and theoretical insights.Earth Science Reviews , Vol. 211, 103402, 23p. PdfMantlegeodynamics

Abstract: In the last few decades, advanced monitoring networks have been extended to the main active volcanoes, providing warnings for variations in volcano dynamics. However, one of the main tasks of modern volcanology is the correct interpretation of surface-monitored signals in terms of magma transfer through the Earth's crust. In this frame, it is crucial to investigate decompression-induced magma degassing as it controls magma ascent towards the surface and, in case of eruption, the eruptive style and the atmospheric dispersal of tephra and gases. Understanding the degassing behaviour is particularly intriguing in the case of poorly explored evolved alkaline magmas. In fact, these melts frequently feed hazardous, highly explosive volcanoes (e.g., Campi Flegrei, Somma-Vesuvius, Colli Albani, Tambora, Azores and Canary Islands), despite their low viscosity that usually promotes effusive and/or weakly explosive eruptions. Decompression experiments, together with numerical models, are powerful tools to examine magma degassing behaviour and constrain field observations from natural eruptive products and monitoring signals. These approaches have been recently applied to evolved alkaline melts, yet numerous open questions remain. To cast new light on the degassing dynamics of evolved alkaline magmas, in this study we present new results from decompression experiments, as well as a critical review of previous experimental works. We achieved a comprehensive dataset of key petrological parameters (i.e., 3D textural data for bubbles and microlites using X-ray computed microtomography, glass volatile contents and nanolite occurrence) from experimental samples obtained through high temperature-high pressure isothermal decompression experiments on trachytic alkaline melts at super-liquidus temperature. We explored systematically a range of final pressures (from 200 to 25 MPa), decompression rates (from 0.01 to 1 MPa s?1), and volatile (H2O and CO2) contents. On these grounds, we integrated coherently literature data from decompression experiments on evolved alkaline (trachytic and phonolitic) melts under various conditions, with the aim to fully constrain the degassing mechanisms and timescales in these magmas. Finally, we simulated numerically the experimental conditions to evaluate strengths and weaknesses in decrypting degassing behaviour from field observations. Our results highlight that bubble formation in evolved alkaline melts is primarily controlled by the initial volatile (H2O and CO2) content during magma storage. In these melts, bubble nucleation needs low supersaturation pressures (? 50-112 MPa for homogeneous nucleation, ? 13-25 MPa for heterogeneous nucleation), resulting in high bubble number density (~ 1012-1016 m?3), efficient volatile exsolution and thus in severe rheological changes. Moreover, the bubble number density is amplified in CO2-rich melts (mole fraction XCO2 ? 0.5), in which continuous bubble nucleation predominates on growth. These conditions typically lead to highly explosive eruptions. However, moving towards slower decompression rates (? 10?1 MPa s?1) and H2O-rich melts, permeable outgassing and inertial fragmentation occur, promoting weakly explosive eruptions. Finally, our findings suggest that the exhaustion of CO2 at deep levels, and the consequent transition to a H2O-dominated degassing, can crucially enhance magma vesiculation and ascent. In a hazard perspective, these constraints allow to postulate that time-depth variations of unrest signals could be significantly weaker/shorter (e.g., minor gas emissions and short-term seismicity) during major eruptions than in small-scale events.
DS1999-0432
1999
Macek, J.J.Macek, J.J., Ducharme, E.B., Lettley, C., McGregor, C.R.Thompson nickel belt project: retrieval of core from Falcon bridge Bucko exploration site near Wabowden.Man. Geological Survey Report Activities, pp. 15-17.ManitobaExploration - drilling, Bucko project, Falconbridge Ltd.
DS2003-0446
2003
Macera, P.Gasperini, D., Blichert Toft, J., Bosch, D., Del Moro, A., Macera, P., Albaraede, F.Upwelling of deep mantle material through a plate window: evidence from theJournal of Geophysical Research, Vol. 107, 12, Dec. 6, pp. DO1 10.1029/2001JB000418MantleGeophysics - seismics, Tectonics
DS200412-0614
2003
Macera, P.Gasperini, D., Blichert Toft, J., Bosch, D., Del Moro, A., Macera, P., Albaraede, F.Upwelling of deep mantle material through a plate window: evidence from the geochemistry of Italian basaltic volcanics.Journal of Geophysical Research, Vol. 107, 12, Dec. 6, pp. DO1 10.1029/2001 JB000418MantleGeophysics - seismics Tectonics
DS201612-2343
2016
Macey, P.H.Thomas, R.J., Macey, P.H., Spencer, C., Dhansay, T., Diener, J.F.A., Lambert, C.W., Frei, D., Nguno, A.The Sperrgebeit Domain, Aurus Mountains, SW Namibia: a ~2020-850 Ma window within the Pan-African Gariep Orogen.Precambrian Research, Vol. 286, pp. 35-58.Africa, NamibiaGeochronology
DS201901-0037
2018
Macey, P.H.Grantham, G., Eglinton, B., Macey, P.H., Ingram,B., Radeneyer, M., Kaiden, H., Manhica, V.The chemistry of Karoo age andesitic lavas along the northern Mozambique coast, southern Africa and possible implications for Gondwana breakup.South African Journal of Geology, Vol. 121, pp. 271-286.Africa, Mozambiquegeodynamics

Abstract: Major, trace, radiogenic isotope and stable isotope data from lavas along the northeastern coast of Mozambique are described. The whole rock composition data demonstrate that the rocks are dominantly andesitic with compositions typical of calc-alkaline volcanic rocks from arc environments. SHRIMP U/Pb data from zircons indicate that the zircons are xenocrystic, having ages of between 500 Ma and 660 Ma, with the age of the lava constrained by Rb/Sr data at ~184 Ma. Strontium, Nd and Pb radiogenic isotope data support an interpretation of extensive mixing between a Karoo age basaltic magma (dolerite) from Antarctica and continental crust similar in composition to the Mozambique basement. Oxygen isotope data also imply a significant crustal contribution to the lavas. Possible tectonic settings for the lavas are at the margin of a plume or from a locally restricted compressional setting during Gondwana breakup processes.
DS201905-1017
2019
Macey, P.H.Boger, S.D., Maas, R., Pastuhov, M., Macey, P.H., Hirdes, W., Schulte, B., Fanning, C.M., Ferreira, C.A.M., Jenett, T., Dallwig, R.The tectonic domains of southern and western Madagascar.Precambrian Research, Vol. 327, pp. 144-175.Africa, Madagascarplate tectonics

Abstract: Southern and western Madagascar is comprised of five tectonic provinces that, from northeast to southwest, are defined by the: (i) Ikalamavony, (ii) Anosyen, (iii) Androyen, (iv) Graphite and (v) Vohibory Domains. The Ikalamavony, Graphite and Vohibory Domains all have intermediate and felsic igneous protoliths of tonalite-trondhjemite-granodiorite-granite composition, with positive ?Nd, and low Sr and Pb isotopic ratios. All three domains are interpreted to be the products of intra-oceanic island arc magmatism. The protoliths of the Ikalamavony and Graphite Domains formed repectively between c. 1080-980?Ma and 1000-920?Ma, whereas those of the Vohibory Domain are younger and date to between c. 670-630?Ma. Different post-formation geologic histories tie the Vohibory-Graphite and Ikalamavony Domains to opposite sides of the pre-Gondwana Mozambique Ocean. By contrast, the Androyen and Anosyen Domains record long crustal histories. Intermediate to felsic igneous protoliths in the Androyen Domain are of Palaeoproterozoic age (c. 2200-1800?Ma), of tonalite-trondhjemite-granodiorite-granite composition, and show negative ?Nd, moderate to high 87Sr/86Sr and variable Pb isotopic compositions. The felsic igneous protoliths of the Anosyen Domain are of granitic composition and, when compared to felsic gneisses of the Androyen Domain, show consistently lower Sr/Y and markedly higher Sr and Pb isotope ratios. Like the Vohibory and Graphite Domains, the Androyen Domain can be linked to the western side of the Mozambique Ocean, while the Anosyen Domain shares magmatic and detrital zircon commonalities with the Ikalamavony Domain. It is consequently linked to the opposing eastern side of this ocean. The first common event observed in all domains dates to c. 580-520?Ma and marks the closure of the Mozambique Ocean. The trace of this suture lies along the boundary between the Androyen and Anosyen Domains and is defined by the Beraketa high-strain zone.
DS202004-0544
2020
Macey, P.H.Will, T.M., Hohn, S., Frimmel, H.E., Gaucher, C., Le Roux, P.J., Macey, P.H.Petrological, geochemical and isotopic data of Neoproterozoic rock units from Uruguay and South Africa: correlation of basement terranes across the South Atlantic.Gondwana Research, Vol. 80, pp. 12-32.South America, Uruguay, Brazil, Africa, Namibiacraton

Abstract: Felsic to intermediate igneous rocks from the Cuchilla Dionisio (or Punta del Este) Terrane (CDT) in Uruguay and the Várzea do Capivarita Complex (VCC) in southern Brazil were emplaced in the Tonian and experienced high-grade metamorphism towards the end of the Cryogenian. Geological and geochemical data indicate an S-type origin and formation in a continental within-plate setting by recycling of lower crustal material that was initially extracted from the mantle in the Palaeoproterozoic. Similar felsic igneous rocks of Tonian age occur in the Richtersveld Igneous Complex and the Vredefontein and Rosh Pinah formations in westernmost South Africa and southern Namibia and have been correlated with their supposed equivalents in Uruguay and Brazil. Geochemical and isotope data of the largely unmetamorphosed felsic igneous rocks in southwestern Africa imply a within-plate origin and formation by partial melting or fractional crystallization of mafic rocks that were extracted from the mantle in the Proterozoic. The parental melts of all of these Tonian igneous rocks from South America and southwestern Africa formed in an anorogenic continental setting at the western margin of the Kalahari Craton and were emplaced in, and/or contaminated by, Namaqua Province-type basement after separation from their source region. However, the source regions and the time of extractions thereof are different and, moreover, occurred at different palaeogeographical latitudes. New petrological data of CDT high-grade gneiss indicate a geothermal gradient of c. 20-25 °C/km, implying continental collisional tectonics following subduction and ocean basin closure at an active continental margin at the eastern edge of present-day South America in the late Cryogenian to early Ediacaran. The associated suture may be traced by the high-grade gneiss and amphibolite-facies mafic rocks in the CDT and probably continues northwards to the Arroio Grande Complex and the VCC in southern Brazil.
DS202102-0205
2020
Macey, P.H.Martin, E.L., Spencer, C.J., Collins, W.J., Thomas, R.J., Macey, P.H., Roberts, N.M.W.The core of Rodinia formed by the juxtaposition of opposed retreating and advancing accretionary orogens.Earth-Science Reviews, Vol. 211, doi.org/10.1016 /j.earscirev.2020 .103413 17p. Pdf Globalcratons

Abstract: Long-lived (800?Ma) Paleo- to Mesoproterozoic accretionary orogens on the margins of Laurentia, Baltica, Amazonia, and Kalahari collided to form the core of the supercontinent, Rodinia. Accretionary orogens in Laurentia and Baltica record predominately radiogenic zircon ?Hf(t) and whole-rock Pb isotopic compositions, short crustal residence times (ca. 0.5?Ga), and the development of arc-backarc complexes. The accretionary orogenic record of Laurentia and Baltica is consistent with a retreating accretionary orogen and analogous to the Phanerozoic western Pacific orogenic system. In contrast, the Mesoproterozoic orogens of Amazon and Kalahari cratons record unradiogenic zircon ?Hf(t) values, ca. 0.8?Ga crustal residence times, and more ancient whole-rock Pb isotopic signatures. The accretionary orogenic record of Amazonia and Kalahari indicates the preferential incorporation of cratonic material in continental arcs of advancing accretionary orogens comparable to the Phanerozoic eastern Pacific orogenic system. Based on similarities in the geodynamic evolution of the Phanerozoic circum-Pacific orogens peripheral to Gondwana/Pangea, we suggest that the Mesoproterozoic accretionary orogens formed as peripheral subduction zones along the margin of the supercontinent Nuna (ca. 1.8-1.6?Ga). The eventual collapse of this peripheral subduction zone onto itself and closure of the external ocean around Nuna to form Rodinia is equivalent to the projected future collapse of the circum-Pacific subduction system and juxtaposition of Australia-Asia with South America. The juxtaposition of advancing and retreating accretionary orogens at the core of the supercontinent Rodinia demonstrates that supercontinent assembly can occur by the closure of external oceans and indicates that future closure of the Pacific Ocean is plausible.
DS201012-0462
2010
MacFadyen, C.MacFadyen, C.The vandalizing effect of irresponsible core sampling: a call for a new code of conduct.Geology Today, Vol. 26, 4, pp. 146-151.GlobalSampling - Not specific to diamonds
DS1984-0578
1984
Macfadyen, D.A.Paterson, N.R., Macfadyen, D.A.An Airborne Electromagnetic Input Magnetometer Survey State Line District,colorado Wyoming.American Institute of Mining, Metallurgical, and Petroleum Engineers (AIME) PREPRINT., No. 84-310, 11P.United States, Colorado, Wyoming, State Line, Rocky MountainsGeophysics, Kimberlite
DS1986-0633
1986
MacFadyen, D.A.Paterson, N.R., MacFadyen, D.A.Airborne electromagnetic (input)/magnetometer survey, State Line Colorado-WyomingAmerican Institute of Mining, Metallurgical, and Petroleum Engineers (AIME) Transactions Vol, Vol. 280, pt. A, pp. 1935-1942Colorado, WyomingBlank
DS1992-0178
1992
MacFadyen, D.A.Brummer, J.J., MacFadyen, D.A., Pegg, C.C.Discovery of kimberlites in the Kirkland Lake area, northern Ontario, Canada. Part I: kimberlite discoveries, sampling, diamondcontent, age, emplacementThe Canadian Institute of Mining, Metallurgy and Petroleum (CIM) Exploration Mining Geology, Vol. 1, No. 4, October pp. 351-370OntarioGeology, geophysics -aeromagnetics, Kimberlite pipes
DS1992-0179
1992
MacFadyen, D.A.Brummer, J.J., MacFadyen, D.A., Pegg, C.C.Discovery of kimberlites in the Kirkland Lake area, northern Ontario, Canada. Part I: early surveys and surficial geologyThe Canadian Institute of Mining, Metallurgy and Petroleum (CIM), Vol. 1, No. 4, October pp. 339-350OntarioHistory, Quaternary, sampling programs
DS1993-0946
1993
MacFadyen, D.A.MacFadyen, D.A.Discovery of kimberlites Kirkland Lake area(Part III) - a decisive contribution by aeromagnetic dat a analysis in conditions of deep overburden.Mid-continent diamonds Geological Association of Canada (GAC)-Mineralogical Association of Canada (MAC) Symposium ABSTRACT volume, held Edmonton May, pp. 31-36.OntarioGeophysics, Geomorphology
DS1995-0871
1995
MacFadyen. D.A.Janse, A.J.A., Novak, N.A., MacFadyen. D.A.Discovery of a new type of highly Diamondiferous kimberlitic rocks in The james Bay Lowlands, Northern OntarioProceedings of the Sixth International Kimberlite Conference Abstracts, pp. 260-262.OntarioKimberlite, Deposit -Kyle Lake area
DS1940-0122
1946
Macfall, R.P.Macfall, R.P., Chagnon, H.E.Gem Hunter's GuideChicago: Science And Mechanics Publishing Co., 95P.GlobalKimberlite
DS1970-0954
1974
Macfarlane, A.Macfarlane, A., Crow, M.J., Arthurs, J.W., Wilkinson, A.F.The Geology and Mineral Resources of Northern Sierra Leone #1Overseas Institute of Geological Sciences International Report, No. 34, 203P.Sierra Leone, West AfricaKimberley, Geology, Diamonds
DS1975-1119
1979
Macfarlane, A.Macfarlane, A., Crowe, M.J., Wilkinson, A.F., Arthurs, J.W.The Geology and Mineral Resources of Northern Sierra Leone #2Geological Survey SIERRA LEONE Bulletin., No. 7Sierra Leone, West AfricaGeology, Diamonds
DS1981-0276
1981
Macfarlane, A.Macfarlane, A., Crow, M.J., Arthurs, J.W., Wilkinson, A.F., Auco.The Geology and Mineral Resources of Northern Sierra Leone #3Institute GEOL. SCIENCES OVERSEAS MEMOIR., MEMOIR No. 7, 103P. DIAMONDS PP. 65-66.Sierra Leone, West AfricaKimberley, Geology, Diamond
DS1993-1423
1993
Macfarlane, A.Sen, G., Macfarlane, A., Srimal, N.Mantle metasomesGeological Society of America Annual Abstract Volume, Vol. 25, No. 6, p. A99 abstract onlyHawaiiMantle, Metasomatism
DS1980-0056
1980
Macfarlane, A.C.Beckinsale, R.D., Gale, N.H., Parkhurst, R.J., Macfarlane, A.C.Discordant Rubidium-strontium and Lead Whole Rock Isochron Ages for ThePrecambrian Research., Vol. 13, No. 1, PP. 43-62.Sierra Leone, West AfricaGeochronology, Geology
DS2001-0713
2001
Macfarlane, A.S.Macfarlane, A.S.A code for the valuation of mineral properties and projects in South AfricaValmin 01, Mineral Asset Valuation Oct. 25-6th., pp.34-50.South AfricaEconomics - legal code, Mineral reserves, resources, valuation, exploration
DS1991-1029
1991
Macfarlane, A.W.Macfarlane, A.W., Holland, H.D.The timing of alkali metasomatism in paleosolsCanadian Mineralogist, Vol. 29, pt. 4, December pp. 1043-1050GlobalGeochronology, Precambrian paleosols
DS1994-1078
1994
Macfarlane, A.W.Macfarlane, A.W., Prol-Ledesma, R-M., Conrad, M.E.Isotope and fluid inclusion studies of geological and hydrothermal processes northern PeruInternational Geology Review, Vol. 36, No. 7, July pp. 645-677PeruGeochronology, Metallogeny
DS1993-0947
1993
Macfarlane, S.N.Macfarlane, S.N.Political and economic change in the former USSR: implications for Canadian competiveness in mineralsCrs Perspectives, No. 42, January pp. 2-9RussiaEconomics, Mineral industry
DS1991-1324
1991
MacFayden, D.A.Pegg, C.C., Brummer, J.J., MacFayden, D.A.Discovery of kimberlite diatremes in the Kirkland Lake area, Ontario #2The Canadian Mining and Metallurgical Bulletin (CIM Bulletin) ., Session, Vol. 84, No. 947, March p. 99. AbstractOntarioKimberlite -diatremes, Kirkland Lake area
DS1996-0868
1996
MacGillivray, L.D.MacGillivray, L.D.Nuggets: a motherlode of useful natural resource and real propertytopics... trespass and technology .Can. Bar Association Continuing Legal Education, Oct. 26, 21pOntarioLegal - interference and property rights, Geophysical surveys
DS1910-0469
1915
Macgregor, A.M.Macgregor, A.M.Notes on a Graphic Intergrowth of Diopside and Ilmenite From the Bembesi Diamond Field, Southern Rhodesia.Geological Society of South Africa Transactions, Vol. 18, PP. 1-4. ALSO: REPLY TO DRAPER, Geological Society STH. AFRZimbabweOxide-silicate-intergrowths, Mineralogy
DS1920-0079
1921
Macgregor, A.M.Macgregor, A.M.The Geology of the Diamond Bearing Gravels of the Somabula Forest. Notes by A.e.v. Zealley.Geological Survey Southern Rhodesia Bulletin., No. 8, PP. 7-38.ZimbabweAlluvial Diamond Placers, Geology
DS1930-0114
1932
Macgregor, A.M.Macgregor, A.M.Walvis Bay Economic Survey. Geological Report with Analyses by E. Golding.In: Report of The Rhodesia-walvis Bay Reconnaissance Survey, PP. 44-54.Southwest Africa, NamibiaGeology, Littoral Diamond Placers
DS1930-0257
1937
Macgregor, A.M.Macgregor, A.M., Ferguson, J.C., Amm, F.L.The Geology of the Country Around the Queen's Mine, BulawayoGeological Survey Southern Rhodesia Bulletin., No. 30, 175P.ZimbabweColussus, Wessels, Geology
DS1940-0156
1947
Macgregor, A.M.Macgregor, A.M.An Outline of the Geological History of Southern RhodesiaRhodesia Geological Survey, Bulletin. No. 38, 73P.ZimbabweGeology, Kimberley
DS1940-0184
1948
Macgregor, A.M.Macgregor, A.M.On Alkaline Ring Complexes in Sabi Valley at the Meeting Of african Geological Surveys Held in London.Chronique de Mines COLON. 16TH., No. 147, PP. 205-206.ZimbabweRelated Rocks
DS1950-0076
1951
Macgregor, A.M.Macgregor, A.M.A Discussion on the Origin of CarbonatitesInternational Geological Congress 18TH., PT. 14, P. 23.South AfricaGeology Kimberlite Pipes, Mining Methods, Recovery Diamond
DS201412-0538
2015
Macgregor, D.Macgregor, D.History of the development of the East African Rift system: a series of interpreted maps through time.Journal of African Earth Sciences, Vol. 101, pp. 232-252.AfricaTectonics
DS201503-0159
2015
MacGregor, D.MacGregor, D.The Fairway concept and chance mapping: African petroleum and carbonatite examples.PDAC 2015, Abstract, 1p.Africa, East AfricaCarbonatite
DS1960-0477
1964
Macgregor, I.D.Macgregor, I.D., Ringwood, A.E.The Natural System Enstatite PyropeCarnegie Institute Yearbook, FOR 1963-1964, PP. 161-163.South AfricaBultfontein, Mineral Chemistry
DS1960-0983
1968
Macgregor, I.D.Macgregor, I.D.Mafic and Ultramafic from the Roberts Victor Kimberlite, South Africa.Geological Society of America (GSA) SPECIAL PAPER., No. 115, PP. 136-137.South AfricaGeology, Petrography
DS1960-1159
1969
Macgregor, I.D.Macgregor, I.D., Carter, J.L.The Genesis of Eclogite Xenoliths from the Roberts Victor Kimberlite Pipe South Africa.American Geophysical Union (AGU) Transactions, Vol. 50, No. 4, P. 342. (abstract.).South AfricaGeology
DS1970-0125
1970
Macgregor, I.D.Macgregor, I.D.An Hypothesis for the Origin of KimberliteAmerican MINERALOGIST., SPECIAL PAPER No. 3, PP. 51-62.South AfricaGenesis
DS1970-0126
1970
Macgregor, I.D.Macgregor, I.D., Carter, J.L.The Chemistry of Clinopyroxenes and Garnets of Eclogite And peridotite Xenoliths from the Roberts Victor Mine, South Africa.Phys. Earth. Plan. International, Vol. 3, PP. 391-397.South AfricaGeochemistry
DS1970-0127
1970
Macgregor, I.D.Macgregor, I.D., Wittkop, R.W.Diopside Ilmenite Intergrowth from the Monastery Mine, Orange Free State, South Africa.Geological Society of America (GSA), Vol. 2, P. 113, (abstract.).South AfricaMineralogy, Petrography
DS1970-0294
1971
Macgregor, I.D.Garlick, G.D., Macgregor, I.D., Vogel, D.E.Oxygen Isotope Ratios in Eclogites from KimberlitesScience., Vol. 172, No. 3987, PP. 1025-1027.South AfricaMineralogy
DS1970-0750
1973
Macgregor, I.D.Macgregor, I.D.Petrological Structure of the Upper Mantle Beneath the South African Shield.1st International Kimberlite Conference, EXTENDED ABSTRACT VOLUME, PP. 207-209.South AfricaTectonics
DS1970-0955
1974
Macgregor, I.D.Macgregor, I.D.The System Mgo Al2os Sio2: Solubility of Al2o3 in Enstatitefor Spinel and Garnet Peridotite Compositions.American MINERALOGIST, \, Vol. 59, PP. 110-119.GlobalMineral Chemistry
DS1975-0027
1975
Macgregor, I.D.Basu, A.R., Macgregor, I.D.Chromite Spinels Fromm Ultramafic XenolithsGeochimica et Cosmochimica Acta ., Vol. 39, PP. 937-945.GlobalGeochemistry
DS1975-0127
1975
Macgregor, I.D.Macgregor, I.D.Petrologic and Thermal Structure of the Upper Mantle Beneath South Africa in the Cretaceous.Physics and Chemistry of the Earth., Vol. 9, PP. 455-466.South AfricaPetrology, Geothermometry, Littoral Diamond Placers
DS1975-1120
1979
Macgregor, I.D.Macgregor, I.D.Mafic and Ultramafic Xenoliths from the Kao Kimberlite PipeProceedings of Second International Kimberlite Conference, Proceedings Vol. 2, PP. 156-172.LesothoPetrography
DS1975-1121
1979
Macgregor, I.D.Macgregor, I.D., Basu, A.R.Petrogenesis of the Mount Albert Ultramafic Massif, QuebecGeological Society of America (GSA) Bulletin., Vol. 90, No. 10, OCTOBER, PP. 898-900. PT. 2. FICHE PP. 1529Canada, QuebecBlank
DS1985-0405
1985
Macgregor, I.D.Macgregor, I.D.The Roberts Victor Eclogites: Ancient Oceanic Crust?Geological Society of America (GSA), Vol. 17, No. 7, P. 650. (abstract.).South AfricaOxygen Isotope Geochemistry
DS1986-0060
1986
MacGregor, I.D.Basu, A.R., Ongley, J.S., MacGregor, I.D.Eclogites, pyroxene geotherm and layered mantle convectionScience, Vol. 233, No. 4770, Sept. 19, pp. 1303-1305MantleBlank
DS1986-0061
1986
Macgregor, I.D.Basu, A.R., Ongley, J.S., Macgregor, I.D.Roberts Victor eclogites, pyroxenes geotherm and layered mantleconvectionEos, Vol. 67, No. 16, April 22, p. 394. (abstract.)South AfricaGeothermometry
DS1986-0512
1986
MacGregor, I.D.MacGregor, I.D., Manton, W.I.The Roberts Victor eclogites: ancient oceanic crustJournal of Geophysical Research, Pt. B, Paper No. 6B5997 (abstract.)South AfricaEclogite
DS1986-0513
1986
MacGregor, I.D.MacGregor, I.D., Manton, W.I.Roberts Victor eclogites: ancient oceanic crustJournal of Geophysical Research, Vol. 91, No. b14, December 10, pp. 14063-14079South AfricaEclogites, Genesis
DS201509-0414
2015
Macgregor, I.D.Macgregor, I.D.Empirical geothermometers and geothermobarometers for spinel peridotite phase assemblages.International Geology Review, Vol. 57, 15, pp. 1940-1974.TechnologyPeridotite, experimental petrology

Abstract: Experimental synthesis of spinel peridotite phase assemblages for a range of compositions that mimic natural samples is used to derive a set of empirical geothermometers and geothermobarometers represented by multiple linear regression best-fit surfaces that link the variables of temperature, pressure, and composition. The calibrated geothermometers use reactions that govern the solubility of Al and Cr in both pyroxenes and the Mg–Fe exchange between silicates and spinel. Geothermobarometers map the Mg–Fe exchange between coexisting olivine and clinopyroxene and pyroxenes and Ca–Mg exchange between coexisting pyroxenes. Application of the geothermometers and geothermobarometers to suites of naturally occurring samples indicates that while reactions governing the Cr and Al solubility and solvus of orthopyroxene give useful estimates of ‘original’ mantle temperatures and pressures, respectively, comparable reactions for clinopyroxene yield estimates that are variably dependent on the transport phase of the sample suites. Temperature and pressure estimates from reactions governing Mg and Fe exchange between silicates and spinel and coexisting silicates are all sensitive to the later transport stage of the samples.
DS201112-1154
2011
Mach, K.Zavada, P., Dedecek, P., Mach, K., Lexa, O., Potuzak, M.Emplacement dynamics of phonolite magma into maar-diatreme structures - correlation of field, thermal modeling and AMS analogue modeling data.Journal of Volcanology and Geothermal Research, Vol. 201, 1-4, pp. 210-226.EuropeGeodynamics - not specific to diamonds
DS1998-1271
1998
MachadoRyan, B., Phillips, Shwetz, MachadoA tale of more than ten plutons - Okay Bay and Staghorn lakeNewfound. Geological Survey, Paper 98-1, pp. 143-71.Quebec, Labrador, UngavaAnorthosites
DS1970-0553
1972
Machado, A. DE M.Machado, A. DE M.Dias E Noites Em DiamantinaUnknown, XEROXBrazilKimberlite, Kimberley, Janlib, History
DS201312-0563
2013
Machado, G.Machado, G., Bilodeau, C., Takpanie, R., St.Onge, M., Rayner, N., Skipton, D., From, R., MacKay, C., Young, M., Creason, G., Braden, Z.Regional bedrock mapping, Hall Peninsula, Nunavut.Geoscience Forum 40 NWT, abstract only p. 26Canada, NunavutMapping
DS1994-1079
1994
Machado, I.F.Machado, I.F., et al.Virgin versus mature reserves: a crucial dilemma for new investmentRaw Materials Report, Vol. 10, No. 1, pp. 8-16GlobalEconomics, Mineral resource development
DS1997-0709
1997
Machado, I.F.Machado, I.F.The CVRD privatization a hard victory for the governmentJournal of Mineral Policy, Business and Environment, Vol. 12, No. 4, pp. 36-41BrazilEconomics, CVRD.
DS2000-0604
2000
Machado, I.F.Machado, I.F., Souza Filho, C.R.Revisiting the largest diamond found in the AmericasIgc 30th. Brasil, Aug. abstract only 1p.Brazil, Minas GeraisDiamond - notable President Vargas
DS201603-0397
2011
Machado, I.F.Machado, I.F.Expedicao Grafte: viagem as berco do maior diamante das Americas. Presidente Vargas diamond found in 1938.Jornal Da Unicamp *** IN POR, Vol. 35, no. 510, 3p. *** In PortugueseSouth America, BrazilDeposit - Coromandel area
DS1997-0912
1997
Machado, KirkhaM.Pilote, P., Dion, C., Joanisse, David, Machado, KirkhaM.Geochronologie des mineralisations d'affiliation magmatique de l'Abitibi -implications geotectoniques.Quebec Department of Mines, DV97-03, p. 47.QuebecGeochronology, Magmatism - not specifc to diamonds
DS1986-0230
1986
Machado, N.Fahrig, W.F., Christie, K.W., Chown, E.H., Janes, D., Machado, N.The tectonic significance of some basic dyke swarms in the Canadian Superior province with special reference to The geochemistry and paleomagnetism of thCanadian Journal of Earth Sciences, Vol. 23, No. 2, February pp. 238-253Ontario, QuebecTectonics, Dyke
DS1987-0430
1987
Machado, N.Machado, N., Heaman, L.Isotope geochemistry of the Coldwell alkaline complex II evidence for crustal contamination from preliminary Sr and neodymium dat a on primary mineralsGeological Association of Canada (GAC), Vol.12, p. 69. abstractOntarioGeochronology, Isotope
DS1989-0915
1989
Machado, N.Machado, N., Goulet, C., Gariepy, C.uranium-lead (U-Pb) geochronology of reactivated Archean basement and Hudsonian metamorphism in northern Labrador Trough.Canadian Journal of Earth Sciences, Vol. 26, pp. 1-15.Quebec, Ungava, LabradorGeochronology, Tectonics
DS1989-0916
1989
Machado, N.Machado, N., Goulet, N., Gariepy, C.uranium-lead (U-Pb) geochronology of reactivated Archean basement and of Hudsonian metamorphism in the northern Labrador...Canadian Journal of Earth Sciences, Vol. 26, pp. 1-15.Labrador, QuebecGeochronology, Labrador Trough
DS1989-0917
1989
Machado, N.Machado, N., Goulet, N., Gariepy, C.uranium-lead (U-Pb) (U-Pb) geochronology of reactivated Archean basement and ofHudsonian metamorphism in the northern Labrador TroughCanadian Journal of Earth Sciences, Vol. 26, No. 1, January pp. 1-15Quebec, Labrador, UngavaProterozoic, Geochronology
DS1990-0968
1990
Machado, N.Machado, N., Krogh, T.E., Weber, W.uranium-lead (U-Pb) geochronology of basement gneisses in the Thompson Belt: evidence for Pikwitonei type crust .. basement..Canadian Journal of Earth Sciences, Vol. 27, pp. 794-802.ManitobaGeochronology, Trans Hudson Orogeny
DS1990-0969
1990
Machado, N.Machado, N., Krogh, T.E.uranium-lead (U-Pb) (U-Pb) geochronology of basement gneisses in the Thompson Belt (Manitoba):evidence for pre-Kenoran and Pikwitonei type crust and early ProterozoicbasementCanadian Journal of Earth Sciences, Vol. 27, No. 6, June pp. 794-802ManitobaThompson belt, Geochronology
DS1992-0690
1992
Machado, N.Heaman, L.M., Machado, N.Timing and origin of Midcontinent rift alkaline magmatism, North America:evidence from the Coldwell ComplexContributions to Mineralogy and Petrology, Vol. 110, No. 2-3, pp. 289-303OntarioAlkaline, Midcontinent Rift
DS1992-0691
1992
Machado, N.Heaman, L.M., Machado, N.Timing and orogen of midcontinent rift alkaline magmatism, North America:evidence from the Coldwell complexMineralogy and Petrology, Vol. 110, No. 2/3, pp. 289-303OntarioTectonics, Alkaline magmatism
DS1992-0971
1992
Machado, N.Machado, N., Carneiro, M.uranium-lead (U-Pb) evidence of late Archean tectono thermal activity in the southern Sao Francisco shield, Brasil.Canadian Journal of Earth Sciences, Vol. 29, pp. 2341-46.BrazilCraton, Geochronology
DS1992-0972
1992
Machado, N.Machado, N., Carneiro, M.uranium-lead (U-Pb) (U-Pb) evidence of late Archean tectono-thermal activity in the southern Sao Francisco shield, BrasilCanadian Journal of Earth Sciences, Vol. 29, No. 11, November, pp. 2341-2346BrazilTectonics, Geochronology
DS1992-0973
1992
Machado, N.Machado, N., Noce, C.M., Ladeira, E.A., Belo de Oliveira, O.uranium-lead (U-Pb) (U-Pb) geochronology of Archean magmatism and Proterozoic metamorphism in the Quadrilatero Ferrifero, southern Sao Francisco craton, BrasilGeological Society of America (GSA) Bulletin, Vol. 104, No. 9, September pp. 1221-1227BrazilGeochronology, Proterozoic
DS1993-0948
1993
Machado, N.Machado, N., David, Scott, Lamothe, Philipe, Gariepyuranium-lead (U-Pb) geochronology of the western Cape Smith Belt: new insights on age of initial rifting and arc magmatismGeological Association of Canada (GAC), Annual Meeting, Vol. 16, p. A78. abstract.Quebec, Ungava, LabradorGeochronology, Tectonics
DS1995-0265
1995
Machado, N.Carignan, J., Machado, N., Gariepy, C.uranium-lead (U-Pb) (U-Pb) isotopic geochemistry of komatiites and pyroxenes from the southern Abitibi greenstone belt, CanadaChemical Geology, Vol. 126, No. 1, Nov. 20, pp. 17-28QuebecKomatiites, Abitibi greenstone belt
DS1997-0710
1997
Machado, N.Machado, N., Clark, T., David, J., Goulet, N.uranium-lead (U-Pb) ages for magmatism and deformation in the New Quebec OrogenCanadian Journal of Earth Sciences, Vol. 34, pp. 716-23.Quebec, Labrador, UngavaMagmatism, Orogeny - New Quebec
DS1997-0913
1997
Machado, N.Pimentel, M.M., Whitehouse, M.J., Machado, N.The Mara Rosa Arc in the To cantins Province: further evidence for Neoproterozoic crustal accretion ..Precambrian Research, Vol. 81. No. 3-4, Feb. 1, pp. 299-Brazil, CentralTectonics, Proterozoic
DS2000-0836
2000
Machado, N.Ross, S., Bernier, F., Machado, N.Buried cratons: completing the Precambrian map of Canada, 2000Geological Association of Canada (GAC)/Mineralogical Association of Canada (MAC) 2000, 1p. abstract.Ontario, Manitoba, Western CanadaTrans Hudson Orogen, Archean Superior Province
DS2001-1131
2001
Machado, N.Stevenson, R.K., Machado, N., Coutreau, BernierBuried Cratons: completing the Precambrian map of Canada, 2001Geological Association of Canada (GAC) Annual Meeting Abstracts, Vol. 26, p. 145.abstract.ManitobaTrans Hudson orogen, Tectonics
DS2002-1555
2002
Machado, N.Stevenson, R., Machado, N., Bernier, F.Isotopic and geochronologic constraints on the Precambrian basement beneath southern Manitoba.Gac/mac Annual Meeting, Saskatoon, Abstract Volume, P.114., p.114.ManitobaGeochronology, Orogen - Trans Hudson
DS2002-1556
2002
Machado, N.Stevenson, R., Machado, N., Bernier, F.Isotopic and geochronologic constraints on the Precambrian basement beneath southern Manitoba.Gac/mac Annual Meeting, Saskatoon, Abstract Volume, P.114., p.114.ManitobaGeochronology, Orogen - Trans Hudson
DS1984-0468
1984
Machado, R.Machado, R.Discussao Da Genese Do Protominerio de Mangabes de Facies Oxido Carbonatico Denominados Bandarrito Municipio de Jacaraci,bahia.Revista Brasileira De Geociencias, Vol. 13, No. 1, PP. 19-22.BrazilRelated Rocks
DS201812-2823
2018
Machado, V.Jerram, D.A., Sharp, T.H., Torsvik, T.H., Poulson, R., Watton, T.H., Freitag, U., Halton, A., Sherlock, S.C., Malley, J.A.S., Finley, A., Roberge, J., Swart, R., Fabregas, P., Ferreira, C.H., Machado, V.Volcanic constraints on the unzipping of Africa from South America: insights from new geochronological controls alone the Angola margin.Tectonophysics, doi.org/10.1016/ j.tecto.2018.07.027 33p.Africa, Angola, South Americageochronology

Abstract: The breakup of Africa from South America is associated with the emplacement of the Paraná-Etendeka flood basalt province from around 134 Ma and the Tristan da Cunha plume. Yet many additional volcanic events occur that are younger than the main pulse of the Paraná-Etendeka and straddle the rift to drift phases of the main breakup. This contribution reports on new geochronological constraints from the Angolan part of the African Margin. Three coastal and one inland section have been sampled stretching across some 400 Km, with 39Ar/40Ar, U-Pb and Palaeontology used to provide age constraints. Ages from the new data range from ~100 to 81 Ma, with three main events (cr. 100, 91 and 82-81 Ma). Volcanic events are occurring within the Early to Late Cretaceous, along this part of the margin with a general younging towards Namibia. With the constraints of additional age information both onshore and offshore Angola, a clear younging trend at the early stages of rift to drift is recorded in the volcanic events that unzip from North to South. Similar age volcanic events are reported from the Brazilian side of the conjugate margin, and highlight the need to fully incorporate these relatively low volume volcanic pulses into the plate tectonic breakup models of the South Atlantic Margin.
DS201904-0750
2019
Machado, V.Jerram, D.A., Sharp, I.R., Torsvik, T.H., Poulsen, R., Machado, V.Volcanic constraints on the unzipping of Africa from South America: insights from new geochronological controls along the Angola margin.Tectonophysics, in press available 27p.Africa, Angola, South Americageochronology

Abstract: The breakup of Africa from South America is associated with the emplacement of the Paraná-Etendeka flood basalt province from around 134?Ma and the Tristan da Cunha plume. Yet many additional volcanic events occur that are younger than the main pulse of the Paraná-Etendeka and straddle the rift to drift phases of the main breakup. This contribution reports on new geochronological constraints from the Angolan part of the African Margin. Three coastal and one inland section have been sampled stretching across some 400?Km, with 39Ar/40Ar, U-Pb and Palaeontology used to provide age constraints. Ages from the new data range from ~100 to 81?Ma, with three main events (cr. 100, 91 and 82-81?Ma). Volcanic events are occurring within the Early to Late Cretaceous, along this part of the margin with a general younging towards Namibia. With the constraints of additional age information both onshore and offshore Angola, a clear younging trend at the early stages of rift to drift is recorded in the volcanic events that unzip from North to South. Similar age volcanic events are reported from the Brazilian side of the conjugate margin, and highlight the need to fully incorporate these relatively low volume volcanic pulses into the plate tectonic breakup models of the South Atlantic Margin.
DS1985-0406
1985
Machado, W.G.Machado, W.G., Moore, M.On the Dodechahedral Growth of Coasted DiamondJournal of Crystal growth, Vol. 71, pp. 718-727GlobalDiamond Morphology
DS1985-0407
1985
Machado, W.G.Machado, W.G., Moore, M., Woods, G.S.On the Dodecahedral Growth of Coated DiamondsJournal of CRYST. GR., Vol. 71, No. 3, PP. 718-727.GlobalExperimental Petrology
DS200712-0386
2006
Machado Alves, F.Grohmann, C.H., Riccomini, C., Machado Alves, F.SRTM based morphotectonic analysis of the Pocos de Caldas alkaline Massif, southeastern Brazil.Computers & Geosciences, Vol. January pp. 10-19.South America, BrazilGeomorphology - alkaline
DS201509-0391
2015
Machaka, E.Cornah, A., Machaka, E.Integration of imprecise and biased dat a into mineral resource estimates.South African Institute of Mining and Metallurgy, Vol. 115, June pp. 523-531.GlobalResource estimation, kriging not specific to diamonds

Abstract: Mineral resources are typically informed by multiple data sources of varying reliability throughout a mining project life cycle. Abundant data which are imprecise or biased or both (‘secondary data’) are often excluded from mineral resource estimations (the ‘base case’) under an intuitive, but usually untested, assumption that this data may reduce the estimation precision, bias the estimate, or both. This paper demonstrates that the assumption is often wasteful and realized only if the secondary data are naïvely integrated into the estimation. A number of specialized geostatistical tools are available to extract maximum value from secondary information which are imprecise or biased or both; this paper evaluates cokriging (CK), multicollocated cokriging (MCCK), and ordinary kriging with variance of measurement error (OKVME). Where abundant imprecise but unbiased secondary data are available, integration using OKVME is recommended. This re-appropriates kriging weights from less precise to more precise data locations, improving the estimation precision compared to the base case and to Ordinary Kriging (OK) of a pooled data-set. If abundant secondary data are biased and imprecise, integration through CK is recommended as the biased data are zero-sum weighted. CK consequently provides an unbiased estimate with some improvement in estimation precision compared to the base case.
DS1999-0150
1999
MacHattieCorrigan, D., Pehrsson, S.J., MacHattie, Piper, WrightLithotectonic framework of the Trans Hudson Orogen in the northwestern Reindeer Zone: update recent mapping.Geological Survey of Canada (GSC), Current Research 1999- C, pp. 169-78.SaskatchewanTectonics, Trans Hudson Orogen
DS2001-0714
2001
MacHattie, T.G.MacHattie, T.G., Jenner, G.A., Corrigan, D.The Wathaman Batholith: evidence for role of enriched lithospheric mantle in a Proterozoic subduction zone.Geological Association of Canada (GAC) Annual Meeting Abstracts, Vol. 26, p.92.abstract.Saskatchewan, ManitobaTectonics, Subduction
DS1996-0869
1996
Machel, H.G.Machel, H.G., Cavell, P.A., Patey, K.S.Isotopic evidence for carbonate cementation and recrystallization, and for tectonic expulsion of fluidsGeological Society of America (GSA), Vol. 108, Sept. pp.1108-19.Alberta, western CanadaWestern Canada Sedimentary Basin, Geochronology
DS1995-1904
1995
Machetal, P.Thoraval, C., Machetal, P., Cazenave, A.Locally layered convection inferred from dynamic models of the earth'smantle.Nature, Vol. 375, No. 6534, June 29, pp. 777-779.MantleSubduction, Geodynamics
DS1991-1030
1991
Machetel, P.Machetel, P., Weber, P.Intermittent layered convection in a model mantle with an endothermic phase change at 670 KM.Nature, Vol. 350, No. 6313, March 7, pp. 55-57GlobalMantle, Layered mantle
DS1991-1031
1991
Machetel, P.Machetel, P., Weber, P.Intermittent layered convection in a model mantle with an endothermic phase change at 670 KM.Nature, Vol. 350, No. 6313, March 7, pp. 55-57GlobalMantle, Layered mantle
DS1995-1905
1995
Machetel, P.Thoraval, C., Machetel, P.Empirical estimates of upper mantle discontinuities topography based upongeodynamical constraints.Eos, Vol. 76, No. 46, Nov. 7. p.F578. Abstract.MantleConvection
DS1998-0198
1998
Machetel, P.Cadek, O., Yuen, D.A., Machetel, P.New perspectives on mantle dynamics from high resolution seismic tomographic model P1200.Pure and Applied Geophys., Vol. 151, No. 2-4, Mar. 1, pp. 503-538.MantleGeophysics - seismics, Geodynamics
DS2003-0856
2003
Machetel, P.Machetel, P., Hunter, E.High mantle temperature during Cretaceous avalancheEarth and Planetary Science Letters, Vol. 208, 3-4, pp. 125-133.MantleGeothermometry
DS200412-1189
2003
Machetel, P.Machetel, P., Hunter, E.High mantle temperature during Cretaceous avalanche.Earth and Planetary Science Letters, Vol. 208, 3-4, pp. 125-133.MantleGeothermometry
DS2002-0023
2002
Machette, K.M.Allaoua Saadi, M.N., Machette,K.M., Haller,K.M., Dart, R.L., Bradley, L-A.Map and database of Quaternary faults and lineaments in BrazilU.s. Geological Survey, OF 02-0230 58p $ 76. http://pubs.usgs.gov/of/2002/ofr-BrazilBlank
DS200412-0019
2002
Machette, K.M.Allaoua Saadi, M.N., Machette,K.M., Haller,K.M., Dart, R.L., Bradley, L-A., De Souza, A.M.P.D.Map and database of Quaternary faults and lineaments in Brazil.U.S. Geological Survey, OF 02-0230 58p $ 76.South America, BrazilMap - structure
DS201808-1766
2018
Machev, P.Machev, P., O'Bannon, E.F., Bozhilov, K.N., Wang, Q., Dobrzhinetskaya, L.Not all moissanites are created equal: new constraints on moissanite from metamorphic rocks of Bulgaria. Earth and Planetary Science Letters, Vol. 498, pp. 387-396.Europe, Bulgariamoissanite

Abstract: Terrestrial moissanite (SiC) is widely reported as an ultra-high pressure mineral occurring in kimberlites, diamonds and ultramafic/mafic rocks of mantle origin. However, the conditions of crystallization remain largely unknown. Moreover, dozens of SiC occurrences have been reported from continental crust sources such as granitoids, andesite-dacite volcanic rocks and their breccia, metasomatic and metamorphic rocks, and even limestones. The validity of many of these reports is still debated primarily due to possible contaminations from the widespread use of synthetic SiC abrasives in samples preparation. Indeed, reports of well-documented in-situ occurrences of moissanite in association with co-existing minerals are still scarce. The only condition of moissanite formation that is agreed upon is that extremely reducing media are required (e.g. 4.5-6 log units below the iron-wustite buffer). Here, we report the new occurrence of moissanite that was found in-situ within the garnet-staurolite-mica schists of Topolovgrad metamorphic group of Triassic age in Southern Bulgaria. The 10-300 ?m moissanite crystals are situated within 0.1-1.2 mm isolated clusters, filled with amorphous carbon and nanocrystalline graphite. Most of moissanite crystals are 15R (rhombohedral) and 6H (hexagonal) polytypes, and one prismatic crystal, found within them, exhibits unusual concentric polytypical zoning with core (15R), intermediate zone (6H) and rim (3C-cubic). Experimental data show that this type of polytypical zonation is likely due to a decrease in temperature (or/and pressure?) and changes in Si/C ratio. Indeed, amphibolite facies metamorphism (500-580?°C - garnet-staurolite zone) followed by a subsequent cooling during the retrograde stage of green schist facies metamorphism (?400-500?°C) could have provided a change in temperature. The SiC containing clusters exhibit evidence that they are pre-metamorphic, and we hypothesize that their protolith was a "lack shale" material likely rich in carbon, hydrocarbon and terrigenous silica. The latter served as a source of isolated chemically-reduced media, which is required for SiC formation. Other concepts to explain moissanite occurrences in metasedimentary rocks are also discussed. Importantly, our findings show that the formation conditions of moissanite are likely more variable than previously recognized.
DS201603-0371
2016
Macheyeki, A.Delcamp, A., Delvaux, D., Kwelwa, S., Macheyeki, A., Kervyn, M.Sector collapse events at volcanoes in the North Tanzanian divergence zone and their implications for regional tectonics. ( Oldoinyo Lengai)Geological Society of America Bulletin, Vol. 128, 1/2, pp. 169-186.Africa, TanzaniaLineaments

Abstract: The North Tanzanian divergence zone along the East African Rift is characterized by active faults and several large volcanoes such as Meru, Ol Doinyo Lengai, and Kilimanjaro. Based on systematic morphostructural analysis of the Shuttle Radar Topographic Mission digital elevation model and targeted field work, 14 debris avalanche deposits were identified and characterized, some of them being - to our knowledge - previously unknown. Our field survey around Mount Meru allowed previous "lahar" deposits to be reinterpreted as debris avalanche deposits and three major collapse events to be distinguished, with the two older ones being associated with eruptions. We used topographic lineaments and faults across the North Tanzanian divergence zone to derive the main tectonic trends and their spatial variations and highlight their control on volcano collapse orientation. Based on previous analogue models, the tectonic regime is inferred from the orientation of the collapse scars and/or debris avalanche deposits. We infer two types of regime: extensional and transtensional/strike-slip. The strike-slip regime dominates along the rift escarpment, but an extensional regime is inferred to have operated for the recent sector collapses. The proposed interpretation of sector collapse scars and debris avalanche deposits therefore provides constraints on the tectonic regime in the region. It is possible that, in some cases, movement on regional faults triggered sector collapse.
DS201701-0027
2016
Machida, S.Pilet, S., Abe, N., Rochat, L., Kaczmarek, M-A., Hirano. N., Machida, S., Buchs, D.M., Baumgartner, P.O., Muntener, O.Pre-subduction metasomatic enrichment of the oceanic lithosphere induced by plate flexure.Nature Geoscience, Vol. 9, pp. 898-903.MantleSubduction

Abstract: Oceanic lithospheric mantle is generally interpreted as depleted mantle residue after mid-ocean ridge basalt extraction. Several models have suggested that metasomatic processes can refertilize portions of the lithospheric mantle before subduction. Here, we report mantle xenocrysts and xenoliths in petit-spot lavas that provide direct evidence that the lower oceanic lithosphere is affected by metasomatic processes. We find a chemical similarity between clinopyroxene observed in petit-spot mantle xenoliths and clinopyroxene from melt-metasomatized garnet or spinel peridotites, which are sampled by kimberlites and intracontinental basalts respectively. We suggest that extensional stresses in oceanic lithosphere, such as plate bending in front of subduction zones, allow low-degree melts from the seismic low-velocity zone to percolate, interact and weaken the oceanic lithospheric mantle. Thus, metasomatism is not limited to mantle upwelling zones such as mid-ocean ridges or mantle plumes, but could be initiated by tectonic processes. Since plate flexure is a global mechanism in subduction zones, a significant portion of oceanic lithospheric mantle is likely to be metasomatized. Recycling of metasomatic domains into the convecting mantle is fundamental to understanding the generation of small-scale mantle isotopic and volatile heterogeneities sampled by oceanic island and mid-ocean ridge basalts.
DS1998-0913
1998
Machin, K.J.Machin, K.J., Barton, E.S.The petrology of the Rex mine kimberlite fissures, central Free State, South Africa.7th International Kimberlite Conference Abstract, pp. 524-6.South AfricaPetrology, mineral chemistry, Deposit - Rex
DS1998-1160
1998
Machin, K.J.Phillips, D., Machin, K.J., Skinner, E.M.W.A petrographic and 40 Ar-39 Ar geochronological study of the Voorspoedkimberlite, implications for origin..South African Journal of Geology, Vol. 101, No. 4, Dec. 1, pp. 299-306.South AfricaKimberlite - Group II magmatism, Deposit - Voorspoed, Argon
DS1990-0970
1990
Machotkin, I.L.Machotkin, I.L., Vrublevskaja, Z.V.Typomorphic associations of secondary minerals of lamproites of centralAldanInternational Mineralogical Association Meeting Held June, 1990 Beijing China, Vol. 2, extended abstract p. 812-813RussiaLampoites, Secondary minerals
DS1990-0343
1990
MacInnes, S.Cole, G., MacInnes, S., Miller, J.Conversion of contoured topography to digital terrain dataComputers and Geosciences, Vol. 16, No. 1, pp. 101-110GlobalProgram, Contoured topography
DS1975-0327
1976
Macintosh, E.K.Macintosh, E.K.A Guide to the Rocks Minerals and Gemstones of Southern Africa.Johannesburg: C. Struik, 96P.GlobalKimberlite
DS1983-0427
1983
Macintosh, E.K.Macintosh, E.K.Rocks, Minerals and Gemstones of Southern AfricaStruik Publishing, South AfricaKimberley
DS1988-0504
1988
MacIntyre, D.Nelson, J., MacIntyre, D.Metallogeny of northeastern British ColumbiaGeoscience Canada, Vol. 15, No. 2, June pp. 113-116British ColumbiaMetallogeny, Diatremes
DS1960-0828
1967
Macintyre, R.M.Gittins, J.G., Macintyre, R.M., Yorck, D.The Ages of Carbonatite Complexes in Eastern CanadaCanadian Journal of Earth Sciences, Vol. 4, PP. 651-655.Canada, QuebecRelated Rocks
DS1970-0342
1971
Macintyre, R.M.Macintyre, R.M.Apparent Periodicity of Carbonatite Emplacement in CanadaNature., Vol. 230, MARCH 22ND. PP. 79-81.United States, Appalachia, New YorkGeochronology, Age Dating
DS1975-0276
1976
Macintyre, R.M.Faerseth, R.B., Macintyre, R.M., Naterstad, J.Mesozoic Alkaline Dikes in the Sunnhordaland Region. Western Norway: Ages, Geochemistry and Regional Significance.Lithos, Vol. 9, PP. 331-345.Norway, ScandinaviaUltramafic And Related Rocks
DS1982-0384
1982
Macintyre, R.M.Macintyre, R.M.Kimberlite-carbonatite: Evolutionary Links?Proceedings of Third International Kimberlite Conference, TERRA COGNITA, ABSTRACT VOLUME., Vol. 2, No. 3, P. 215, (abstract.).GlobalKimberlite, Radiometric, Dating, Iridium Anomaly
DS1989-1008
1989
MacIntyre, R.M.Menzies, M.A., Halliday, A.N., Hunter, R.H., MacIntyre, R.M., UptonThe age, composition and significance of a xenolith bearing monchiquitedike, Lewis, ScotlandGeological Society of Australia Inc. Blackwell Scientific Publishing, Special, No. 14, Vol. 2, pp. 843-852ScotlandMantle xenoliths
DS1970-0343
1971
Macintyre, R.N.Macintyre, R.N., Dawson, J.B.Radiometric Dating of Alkaline Intrusions in Southern AfricaAnnual SOC. GEOL. BELG., Vol. 94, P. 120.South AfricaDating
DS1975-0328
1976
Macintyre, R.N.Macintyre, R.N., Dawson, J.B.Age and Significance of Some South African KimberlitesEur. Colloq. Geochron. Cosmochron. Isotope Geol. 4th. Held A, ABSTRACT VOLUME, P. 66.South AfricaGeochronology
DS1992-0974
1992
Mack, G.H.Mack, G.H., James, W.C.Paleosols for sedimentologistsGeological Society of America Short Course, Notes, 125pGlobalShort Course, Sedimentology, paleosols
DS1993-0949
1993
Mack, G.H.Mack, G.H., James, W.C., Monger, H.C.Classification of paleosolsGeological Society of America (GSA) Bulletin, Vol. 105, No. 2, February pp. 129-136GlobalLaterites, Paleosols
DS1994-1080
1994
Mack, G.H.Mack, G.H., James, W.C.Paleoclimate and the global distribution of paleosolsJournal of Geology, Vol. 102, No. 3, May pp. 360-366GlobalPaleoclimate, Paleosols, Laterites
DS1994-1081
1994
Mack, G.H.Mack, G.H., James, W.C.Paleoclimate and the global distribution of paleosolsJournal of Geology, Vol. 102, No. 3, May pp. 360-366.GlobalPaleosols -not specific to diamonds
DS1984-0587
1984
Mack, J.F.Plaisted, P.S., Mack, J.F.The metallurgical evaluation of AK1 kimberlite to establish process design criteriaIn: Darwin Conference, Publishing Australasian Institute Min. Metallurgy, pp. 151-160AustraliaMetallurgy, Mining Methods
DS1993-1749
1993
Mack, L.E.Wittke, J.H., Mack, L.E.The mantle source for continental alkaline rocks of the Balcones Texas: trace -element and isotopic evidence.Journal of Geology, Vol. 101, No. 3, May pp. 333-344.GlobalAlkaline rocks, Balcones
DS1960-0271
1962
Mack, S.Mack, S.Post Stormking Dikes in the Hudson Highlands of New YorkNew York Academy of Sciences ANNALS, Vol. 93, PP. 923-933.United States, Appalachia, New YorkRelated Rocks, Petrography
DS1860-0113
1870
Mackay, A.Mackay, A.A Visit to Sydney and the Cudgegong MineMelbourne:, 64P.Australia, New South WalesTravelogue
DS2002-0083
2002
Mackay, A.G.E.August, C.M., Esterhuizey, G., Mackay, A.G.E.The application of geophysical techniques in the delineation of diamond bearing shallow marine deposits.11th. Quadrennial Iagod Symposium And Geocongress 2002 Held Windhoek, Abstract p. 19.NamibiaGeophysics - sonar, chirp sub bottom profiling, Alluvials
DS1991-1032
1991
Mackay, A.L.Mackay, A.L., Terrones, H.Diamond from graphiteNature, Vol. 352, No. August 29, p. 762GlobalDiamond morphology, Graphite
DS201312-0563
2013
MacKay, C.Machado, G., Bilodeau, C., Takpanie, R., St.Onge, M., Rayner, N., Skipton, D., From, R., MacKay, C., Young, M., Creason, G., Braden, Z.Regional bedrock mapping, Hall Peninsula, Nunavut.Geoscience Forum 40 NWT, abstract only p. 26Canada, NunavutMapping
DS201412-0539
2014
Mackay, D.A.R.Mackay, D.A.R., Simandl, G.J.Geology, market and supply chain of niobium and tantalum - a review.Mineralium Deposita, Vol. 49, 8, pp. 1025-1047.GlobalNiobium
DS201512-1936
2015
Mackay, D.A.R.Mackay, D.A.R., Simandl, G.J.Niobium and tantalum: geology, markets, and supply chains.Symposium on critical and strategic materials, British Columbia Geological Survey Paper 2015-3, held Nov. 13-14, pp. 13-22.GlobalNiobium, tantalum

Abstract: Until 2014, niobium (Nb) and tantalum (Ta) were on the critical metals list of the European Union (European Commission, 2011; 2014). Both Ta and Nb have high levels of supply chain risk and even temporary disruptions in supply could be difficult to cope with. The Ta market is subject to infl ux of ‘conflict’ columbite-tantalite concentrate, or ’Coltan,’ into the supply chain, displacing production in Australia and Canada. The growing consumer appetite for goods made of ethically sourced or ‘confl ict-free’ minerals and metals has put pressure on manufacturers of components for consumer electronics, such as smart phones, laptop computers, computer hard drives, digital cameras, GPS navigation systems, and airbag triggers to stop using Ta from ‘confl ict’ areas. Other uses of Ta include medical implants, super alloys used in jet turbine and rocket nozzle production, corrosion prevention in chemical and nuclear plants, as a sputtering target, and in optical lenses (Tantalum-Niobium International Study Center, 2015a, b). These applications make Ta economically and strategically important to industrialised countries (European Commission, 2011, 2014; Brown et al., 2012; Papp, 2012). Niobium (Nb) is primarily used in high-strength low-alloy (HSLA) steel used extensively in the oil and gas and automotive industries. Niobium is also a major component in vacuum-grade alloys used in rocket components and other aeronautic applications (Tantalum-Niobium International Study Center, 2015a, c). Demand for Nb is increasing due to greater use of Nb in steel making in China, India, and Russia (Roskill, 2013b; Mackay and Simandl, 2014). Because most primary Nb production is restricted to a single country (Brazil), security of supply is considered at risk (European Commission, 2014). New sources of supply may be developed to diversify geographic location of supply for strategic reasons (Mackay and Simandl, 2014). Herein we summarize the geology, market, and supply chains of Niobium and Tantalum metals.
DS201512-1937
2015
Mackay, D.A.R.Mackay, D.A.R., Simandl, G.J.,Ma, W., Gravel, J., Redfearn, M.Indicator minerals in exploration for speciality metal deposits: a QEMSCAN approach.Symposium on critical and strategic materials, British Columbia Geological Survey Paper 2015-3, held Nov. 13-14, pp. 211-218.TechnologyRare earths

Abstract: Quantitative Evaluation of Materials by Scanning electron microscopy (QEMSCAN®) was used to assess carbonatite indicator minerals in fl uvial sediments from the drainage area of the Aley carbonatite, in north-central British Columbia. QEMSCAN® is a viable method for rapid detection and characterization of carbonatite indicator minerals with minimal processing other than dry sieving. Stream sediments from directly above, and up to 11 km downstream, of the carbonatite deposit were selected for this indicator mineral study. The geology of the Aley carbonatite is described by Mäder (1986), Kressal et al. (2010), McLeish (2013), Mackay and Simandl (2014), and Chakhmouradian et al. (2015). Traditional indicator mineral exploration methods use the 0.25-2.0 mm size fraction of unconsolidated sediments (Averill, 2001, 2014; McCurdy, 2006, 2009; McClenaghan, 2011, 2014). Indicator minerals are detectable by QEMSCAN® at particle sizes smaller than those used for hand picking (<0.25 mm). Pre-concentration (typically by shaker table) is used before heavy liquid separation, isodynamic magnetic separation, optical identifi cation using a binocular microscope, and hand picking (McClenaghan, 2011). Following additional sieving, the 0.5-1 and 1-2 mm fractions are hand picked for indicator minerals while the 0.25-0.5 mm fraction is subjected to paramagnetic separation before hand picking (Averill, 2001; McClenaghan, 2011). Hand picking indicator minerals focuses on monomineralic grains, and composite grains may be lost during processing. Composite grains are diffi cult and time consuming to hand pick and characterize using optical and Scanning Electron Microscopy (SEM) methods. A single grain mount can take 6-12 hours to chemically analyse (Layton- Matthews et al., 2014). Detailed sample analysis using the QEMSCAN® Particle Mineral Analysis routine allows for 5-6 samples to be analyzed per day. When only mineral identifi cation and mineral concentrations and counts are required, the use of a Bulk Mineral Analysis routine reduces the analysis time from ~4 hours to ~30 minutes per sample.
DS201605-0864
2016
Mackay, D.A.R.Mackay, D.A.R., Simandl, G.J., Ma, W., Redfearn, M., Gravel, J.Indicator mineral-based exploration for carbonatites and related specialty metal deposits - a QEMSCAN orientation survey, British Columbia. Aley, Lonnie, WicheedaJournal of Geochemical Exploration, Vol. 165, pp. 159-173.Canada, British ColumbiaGeochemistry - carbonatites

Abstract: This orientation survey indicates that Quantitative Evaluation of Materials by Scanning electron microscopy (QEMSCAN®) is a viable alternative to traditional indicator mineral exploration approaches which involve complex processing followed by visual indicator mineral hand-picking with a binocular microscope. Representative polished smear sections of the 125-250 ?m fraction (dry sieved and otherwise unprocessed) and corresponding Mozley C800 table concentrates from the drainages of three carbonatites (Aley, Lonnie, and Wicheeda) in the British Columbia Alkaline Province of the Canadian Cordillera were studied. Polished smear sections (26 × 46 mm slide size) contained an average of 20,000 exposed particles. A single section can be analyzed in detail using the Particle Mineral Analysis routine in approximately 3.5-4.5 h. If only mineral identification and mineral concentrations are required, the Bulk Mineral Analysis routine reduces the analytical time to 30 min. The most useful carbonatite indicator minerals are niobates (pyrochlore and columbite), REE-fluorocarbonates, monazite, and apatite. Niobate minerals were identified in the 125-250 ?m fraction of stream sediment samples more than 11 km downstream from the Aley carbonatite (their source) without the need for pre-concentration. With minimal processing by Mozley C800, carbonatite indicator minerals were detected downstream of the Lonnie and Wicheeda carbonatites. The main advantages of QEMSCAN® over the traditional indicator mineral exploration techniques are its ability to: 1) analyze very small minerals, 2) quickly determine quantitative sediment composition and mineralogy by both weight percent and mineral count, 3) establish mineral size distribution within the analyzed size fraction, and 4) determine the proportions of monomineralic (liberated) grains to compound grains and statistically assess mineral associations in compound grains. One of the key advantages is that this method permits the use of indicator minerals based on their chemical properties. This is impossible to accomplish using visual identification.
DS201801-0063
2017
Mackay, D.A.R.Simandl, G.J., Mackay, D.A.R., Ma, X., Luck, P., Gravel, J., Akam, C.The direct indicator mineral concept and QEMSCAN applied to exploration for carbonatite and carbonatite related ore deposits.in: Ferbey, T. Plouffe, A., Hickein, A.S. eds. Indicator minerals in tills and stream sediments of the Canadian Cordillera. Geological Association of Canada Special Paper,, Vol. 50, pp. 175-190.Canada, British Columbiacarbonatite - Aley, Lonnie, Wicheeda

Abstract: This volume consists of a series of papers of importance to indicator minerals in the Canadian Cordillera. Topics include the glacial history of the Cordilleran Ice Sheet, drift prospecting methods, the evolution of survey sampling strategies, new analytical methods, and recent advances in applying indicators minerals to mineral exploration. This volume fills a notable knowledge gap on the use of indicator minerals in the Canadian Cordillera. We hope that the volume serves as a user guide, encouraging the wider application of indicator minerals by the exploration community.
DS1994-0312
1994
MacKay, R.Clarke, D.B., Mitchell, R.H., Chapman, C.A.T., MacKay, R.Occurrence and origin of djerfisherite from Elwin Bay kimberlite, SomersetIsland, northwest Territories.Canadian Mineralogist, Vol. 32, No. 4, Dec. pp. 815-824.Northwest Territories, Somerset IslandMineralogy
DS1990-0336
1990
MacKay, R.M.Clarke, D.B., MacKay, R.M.An ilmenite garnet clinopyroxenite nodule from Matsoku: evidence for oxide rich liquid immiscibility in kimberlitesCanadian Mineralogist, Vol. 28, pt. 2, June pp. 229-239LesothoGeothermometry, Garnet analyses Xenolith
DS202005-0748
2020
Mackensie, S.Mackensie, S., Everingham, J-A., Bourke, P.The social dimensions of mineral exploration. Not specific to diamonds - but interestSEG Discovery ( former NewsLetter), No. 121, April, pp. 16-28.Globalgeoscience

Abstract: Geoscientists are often the first point of contact a local community has with a company conducting mineral exploration. The behavior of the geoscientists and the interest they take in understanding the local community and stakeholders will have ramifications well beyond their direct exploration activities. This article highlights some of the positive and negative impacts exploration can have for local communities (in part drawing on interviews with experienced geoscientists and others involved in exploration). The article explores the increasing complexity of deposits in terms of environmental, economic, social, and political parameters and the increasing scrutiny by local stakeholders and the international community. We argue that, although geoscientists are not social performance specialists, they still need the awareness, tools, and capabilities to understand and manage the social aspects of their exploration activities commensurate with the stage and resourcing of the project. We propose three interrelated aspects of social performance that can be applied during mineral exploration: meaningful and positive engagement, acquiring and documenting a social knowledge base, and strategic investment in the community. Two case studies provide cautionary examples of failure to do so and two case studies highlight how, through careful engagement and strategic collaboration, mutually beneficial and positive relationships can be built from early exploration.
DS1992-0975
1992
Mackenzie, B.W.Mackenzie, B.W., Doggett, M.D.Economics of mineral exploration in AustraliaCentre for Resource Studies, 269p. $ 125.00AustraliaEconomics, Book -ad
DS1992-0976
1992
Mackenzie, B.W.Mackenzie, B.W., Doggett, M.D.Economic potential of mining in Manitoba: developing taxation policyCentre for Resource Studies, June 124pManitobaEconomics, Legal, Policy and mining taxation
DS1993-0950
1993
Mackenzie, B.W.Mackenzie, B.W., Doggett, M.How to appraise mineral resourcesCrs Perspective, No. 42, January pp. 28-34CanadaEconomics, MIneral appraisal, ore reserves
DS1994-0439
1994
Mackenzie, B.W.Doggett, M.D., Mackenzie, B.W.Mineral potential on Canada's frontiersCrs Perspectives, No. 48, February pp. 19-27CanadaEconomics, Mineral policies for remote areas
DS1995-1135
1995
Mackenzie, B.W.Mackenzie, B.W., Doggett, M.D.The changing economic climate for mineral supply in CanadaCentre for Resource Studies, Mon. 31, 100p. $ 25.00CanadaEconomics, Mineral supply
DS1994-1082
1994
Mackenzie, D.Mackenzie, D.Where has all the carbon gone?New Science, January pp. 31-33GlobalCarbon dioxide, Atmosphere, lithosphere
DS1960-0167
1961
Mackenzie, D.H.Mackenzie, D.H.Geology and Mineral Resources of the Gbangbama AreaGeological Survey SIERRA LEONE Bulletin., No. 3, UNPUBL.Sierra Leone, West AfricaGeology, Kimberlite, Diamond
DS1998-0117
1998
Mackenzie, D.H.Berkman, D.A., Mackenzie, D.H.Geology of Australian and Papua New Guinean mineral depositsAusIMM, Mon. 22, 880pAustralia, Papua New GuineaBook - table of contents, Mineral deposits, gold, copper, zinc, nickel
DS200612-0040
2006
Mackenzie, F.T.Arvidson, R.S., Mackenzie, F.T., Guidry, M.MAGic: a Phanerozoic model for the geochemical cycling of major rock forming components.American Journal of Science, Vol. 306, 3, pp. 135-190.TechnologyComputer program - MAGic, geochemistry
DS1860-0153
1871
Mackenzie, J. REV.Mackenzie, J. REV.Ten Years North of the Orange River from 1859-1869Edinburgh: Edmunston And Douglas, 523P.Africa, South Africa, Cape ProvinceHistory
DS1985-0299
1985
Mackenzie, J.K.Humble, P., Mackenzie, J.K., Olsen, A.Platelet Defects in Natural Diamond. 1. Measurement of DisplacementPhil. Magazine Part A., Vol. 52, No. 5, Nov. pp. 605-621GlobalMineral Chemistry, Diamond Morphology
DS1997-0711
1997
Mackenzie, J.M.Mackenzie, J.M., Canil, D.Petrological aspects of the Barra do Itapirapua carbonatite, southernBrasil.Lithoprobe Slave/SNORCLE., pp. 223-4.Northwest TerritoriesMantle, Petrology
DS1998-0914
1998
Mackenzie, J.M.Mackenzie, J.M., Canil, D.Upper mantle xenoliths from the Archean Slave Craton: composition and thermal evolution of a kimberlite ProvinceGeological Association of Canada (GAC)/Mineralogical Association of Canada (MAC) Abstract Volume, p. A114. abstract.Northwest TerritoriesThermobarometry, Xenoliths
DS1999-0433
1999
Mackenzie, J.M.Mackenzie, J.M., Canil, D.Composition and thermal evolution of cratonic mantle beneath the central Archean Slave Province, northwest Territories.Contributions to Mineralogy and Petrology, Vol. 134, No. 4, pp. 313-324.Northwest TerritoriesCraton, Geothermometry
DS2003-0319
2003
MacKenzie, J.M.Davis, W.J., Canil, D., MacKenzie, J.M., Carbno, G.B.Petrology and U Pb geochronology of lower crust xenoliths and the development of aLithos, Vol. 71, 2-4, pp. 541-573.Northwest Territories, NunavutGeochronology
DS200412-0419
2003
MacKenzie, J.M.Davis, W.J., Canil, D., MacKenzie, J.M., Carbno, G.B.Petrology and U Pb geochronology of lower crust xenoliths and the development of a craton, Slave Province, Canada.Lithos, Vol. 71, 2-4, pp. 541-573.Canada, NunavutGeochronology
DS200512-0668
2005
MacKenzie, J.M.MacKenzie, J.M., Canil, D., Johnston, S.T., English, J., Mihalynuk, M.G., Grant, B.First evidence for ultrahigh pressure garnet peridotite in the North American Cordillera.Geology, Vol. 33, 2, pp. 105-108.Canada, Yukon, British ColumbiaUHP, Mantle lithosphere
DS200612-0218
2005
MacKenzie, J.M.Canil, D., Mihalynuk, M., MacKenzie, J.M., Johnston, S.T., Grant, B.Diamond in the Atlin-Nakin a region, British Columbia: insights from heavy minerals in stream sediments.Canadian Journal of Earth Sciences, Vol. 42, 12, Dec. pp. 2161-2171.Canada, British Columbia, Yukon, United States, AlaskaGeochemistry
DS1992-1488
1992
MacKenzie, P.Strang, J., MacKenzie, P.A manual on Mines rescue, safety and gas detectionColorado School of Mines Press, 475p. $ 45.00 United StatesGlobalBook -ad, Mines rescue, safety, gas
DS1900-0029
1900
Mackenzie, W.D.Mackenzie, W.D., Skead, A.South Africa Its History, Heroes and WarsChicago: American Literary And Musical Association, 663P.Africa, South AfricaKimberley, History, Politics
DS1984-0469
1984
Mackenzie, W.S.Mackenzie, W.S., Donaldson, C.H., Guilford, C.Kimberlite and Garnet PeridotiteAtlas of Igneous Rocks And Their Textures, J.wiley- Halstead, 148P. PP. 81-82.GlobalPhotomicrographs
DS1990-1622
1990
Mackenzie, W.S.Zeng Rongshu, Mackenzie, W.S.Variation of the primary field of leucite under water deficient conditions in the system northeast-Ks-Q-H2O at PH2O =kbInternational Mineralogical Association Meeting Held June, 1990 Beijing China, Vol. 1, extended abstract p. 129-130ChinaExperimental petrology, Leucite
DS1998-0007
1998
MacKenzie, W.S.Adams, A.E., MacKenzie, W.S.A colour atlas of carbonate sediments and rocks under the microscopeOxford University of Press, 192p. approx. $ 90.00GlobalBook - ad, Atlas - carbonate sediments
DS1998-0915
1998
Mackey, K.G.Mackey, K.G., Fujita, K., Ruff, L.J.Crustal thickness of northeast RussiaTectonophysics, Vol. 284, No. 3-4, Jan. 30, pp. 283-298.Russia, SiberiaTectonics, Crust
DS1997-1140
1997
Mackey, T.Tarlowksi, C., Gunn, P.J., Mackey, T.Enhancements of the magnetic map of AustraliaAgso Journal, Australian Geology And Geophysics, Vol. 17, No. 2, pp. 77-82AustraliaGeophysics - airborne, Geophysics - magnetics
DS1998-0887
1998
Mackey, T.Liu, S., Mackey, T.Using images in a geological interpretation of magnetic dataAgso Research Newsletter, No. 28, May pp. 17-19AustraliaLithology, structure, Geophysics - magnetics
DS1993-0951
1993
Mackey, T.S.Mackey, T.S.No tomorrow? environmental matters affecting new industrial plants in theUSAEngineering and Mining Journal, Vol. 194, No. 12, December pp. NA 16A, 16B, 16D.United StatesEnvironmental, Mining
DS1970-0751
1973
Mackidd, D.G.Mackidd, D.G.Interpretation of Gravity and Magnetics North of Lake Superior.Msc. Thesis, University Toronto, 103P.GlobalMid-continent, Geophysics
DS201712-2702
2017
Mackintosh, V.Mackintosh, V., Kohn, B., Gleadow, A., Tian, Y.Phanerozoic morphotectonic evolution of the Zimbabwean craton: unexpected outcomes from a multiple low temperature thermochronology study.Tectonics, Vol. 36, 10, in press availableAfrica, Zimbabwecraton, geothermometry

Abstract: The fragmentary Phanerozoic geological record of the anomalously elevated Zimbabwe Craton makes reconstructing its history difficult using conventional field methods. Here we constrain the cryptic Phanerozoic evolution of the Zimbabwe Craton using a spatially extensive apatite (U-Th-Sm)/He (AHe), apatite fission track (AFT), and zircon (U-Th)/He (ZHe) data set. Joint thermal history modeling reveals that the region experienced two cooling episodes inferred to be the denudational response to surface uplift. The first and most significant protracted denudation period was triggered by stress transmission from the adjacent ~750-500 Ma Pan-African orogenesis during the amalgamation of Gondwana. The spatial extent of this rejuvenation signature, encompassing the current broad topographic high, could indicate the possible longevity of an ancient topographic feature. The ZHe data reveal a second, minor denudation phase which began in the Paleogene and removed a kilometer-scale Karoo cover from the craton. Within our data set, the majority of ZHe ages are younger than their corresponding AHe and AFT ages, even at relatively low eU. This unexpectedly recurrent age “inversion” suggests that in certain environments, moderately, as well as extremely, damaged zircons have the potential to act as ultra-low-temperature thermochronometers. Thermal history modeling results reveal that the zircon radiation damage accumulation and annealing model (ZRDAAM) frequently overpredicts the ZHe age. However, the opposite is true for extremely damaged zircons where the ZHe and AHe data are also seemingly incompatible. This suggests that modification of the ZRDAAM may be required for moderate to extreme damage levels.
DS2003-0857
2003
Macklem, K.Macklem, K.Diamonds with an edge. Canadian stones are transforming the industryMacleans, Sept. 8, pp. 52-55.Ontario, Wawa, Northwest Territories, Nunavut, SaskatchewanNews item
DS200412-1190
2003
Macklem, K.Macklem, K.Diamonds with an edge. Canadian stones are transforming the industry.Macleans Magazine, Sept. 8, pp. 52-55.Canada, Ontario, WawaNews item
DS2002-1238
2002
Mackley, R.D.Pederson, J.L., Mackley, R.D., Eddleman, J.L.Colorado Plateau uplift and erosion evaluated using GISGsa Today, Vol. 12, No. 8, August pp. 4-10.Colorado, Arizona, Utah, New MexicoStratigraphic - geomorphology, epeirogeny
DS1990-0449
1990
Macko, S.A.Engel, M.H., Macko, S.A., Silfer, J.A.Carbon isotope composition of individual amino acidss in the MurchisonmeteoriteNature, Vol. 348, No. November 1, pp. 47-49GlobalMeteorite, Geochronology -CI
DS1993-0410
1993
Macko, S.A.Engel, M.H., Macko, S.A.Organic geochemistry.. principles and applicationsPlenum Publishing Corp, $ approx. 90.00 United StatesGlobalBook -table of contents, ad, Geochemistry -organic
DS1997-0316
1997
Macko, S.A.Engel, M.H., Macko, S.A.Organic geochemistry - principles and applicationsPlenum Publ, $ 100.00 approxGlobalBook - ad, Organic geochemistry
DS2002-0186
2002
Mackwell, S.Bolfan Casanova, N., Mackwell, S., Keppler, H., McCammon, C., Rubie, D.C.Pressure dependence of H solibility in magnesiowustite up to 25 GPa: implications forGeophysical Research Letters, Vol. 29,10,May15,pp.89-MantleGeochemistry
DS1990-0971
1990
Mackwell, S.J.Mackwell, S.J., Kohlstedt, D.L.Diffusion of hydrogen in olivine: implications for water in the mantleJournal of Geophysical Research, Vol. 95, B4, April 10, pp. 5079-5088GlobalMantle, Olivine
DS1992-0405
1992
Mackwell, S.J.Dyar, M.D., McGuire, A.V., Mackwell, S.J.Fe3/H and D/H in kaersutites- misleading indicators of mantle sourcefugacitiesGeology, Vol. 20, No. 6, June pp. 565-568GlobalMantle, iron, Hydrogen, Geochronology
DS1993-0385
1993
Mackwell, S.J.Dyar, M.D., Mackwell, S.J., Cross, L.R., Robertson, J.D.Crystal chemistry of iron and Hydrogen in mantle kaersutite: implications for mantle MetasomatismAmerican Mineralogist, Vol. 78, No. 9, 10, September-October pp. 968-979MantleMetasomatism, iron, Hydrogen, Geochemistry
DS2002-0977
2002
Mackwell, S.J.Mackwell, S.J., Paterson, M.S.New developments in deformation studies: high strain deformationPlastic Deformation of Minerals and Rocks, Geological Society of America, No. 51, Chapter 1, pp. 1-17.MantleUHP
DS200412-1191
2002
Mackwell, S.J.Mackwell, S.J., Paterson, M.S.New developments in deformation studies: high strain deformation.Plastic Deformation of Minerals and Rocks, Geological Society of America, Mineralogy and Geochemistry Series, No. 51, Chapter 1, pp. 1-17.MantleUHP
DS200712-0090
2006
Mackwell, S.J.Bolfan Casanova, N., McCammon, C.A., Mackwell, S.J.Water in transition zone and lower mantle minerals.American Geophysical Union, Geophysical Monograph, No. 168, pp. 57-68.MantleWater
DS200712-0238
2007
Mackwell, S.J.Demouchy, S., Mackwell, S.J., Kohlstedt, D.L.Influence of hydrogen on Fe Mg interdiffusion in (Mg,Fe)O and implications for Earth's lower mantle.Contributions to Mineralogy and Petrology, Vol. 154, 3m pp. 279-289.MantleMineralogy
DS200812-0660
2008
Mackwell, S.J.Li, ZX., Lee, C-T.A, Peslier, A.H., Lenardic, A., Mackwell, S.J.Water contents in mantle xeonoliths from the Colorado Plateau and vicinity: implications for the mantle rheology and hydration induced thinking of lithosphereJournal of Geophysical Research, Vol. 113, B9, B09210.MantleWater content
DS200812-1325
2008
Mackwell, S.J.Zheng-Xue, A.L., Lee, C-T.A., Peslier, A.H., Lenardic, A., Mackwell, S.J.Water contents in mantle xenoliths from the Colorado Plateau and vicinity: implications for mantle rheology and hydration induced thinning of continental lithosph.Journal of Geophysical Research, Vol. 113. B09210United States, Colorado PlateauPeridotite
DS1995-1136
1995
MacLachlan, K.MacLachlan, K., Helmsteadt, H.Geology and geochemistry of an Archean mafic dike complex in the Chan Formation -revised plate tectonicsCanadian Journal of Earth Sciences, Vol. 32, No. 5, May pp. 614-630Northwest TerritoriesYellowknife greenstone belt, Tectonics
DS2000-0605
2000
MacLachlan, K.MacLachlan, K., Hanmer, S., Berman, W.J., Ryan, RelfComplex, protracted, Proterozoic reworking Western Churchill Province: the craton that wouldn't grow up.Geological Association of Canada (GAC)/Mineralogical Association of Canada (MAC) 2000, 4p. abstractWestern Canada, Northwest Territories, SaskatchewanTectonics - craton, Geothermometry
DS200512-0669
2005
Maclachlan, K.Maclachlan, K., Davis, W.J., Relf, C.Paleoproterozoic reworking of an Archean thrust fault in the Hearne Domain, Western Churchill Province: U Pb geochronological constraints.Canadian Journal of Earth Sciences, Vol. 42, 7, July pp. 1-18.Canada, Northwest Territories, NunavutGeotectonics
DS1999-0434
1999
MacLatchy, P.MacLatchy, P., Witteman, J.Development of an aquatic effects monitoring program for BHP's Ekati diamond mine, northwest Territories.The Canadian Mining and Metallurgical Bulletin (CIM Bulletin) ., Vol. 92, No. 1028, Mar. p. 112, abstractNorthwest TerritoriesMining - environment, Deposit - Ekati
DS201706-1105
2017
MacleanSt. Onge, M.R., Harrison, J.C., Paul, D., Tella, S., Brent, T.A., Jauer, C.D., MacleanTectonic map of Arctic Canada (TeMAC): a first derivative product from Canada in 3-D geological compilation work.GAC annual meeting, 1p. AbstractCanadatectonics
DS1991-0300
1991
Maclean, B.C.Cook, D.G., Maclean, B.C.Seismic interpretation, northern interior plains, Canada: bedding parallel thrusts versus Wyoming style basement block upliftsGeological Society of America Annual Meeting Abstract Volume, Vol. 23, No. 5, San Diego, p. A 422Saskatchewan, WyomingGeophysics -seismics, Tectonics
DS1992-0298
1992
MacLean, B.C.Cook, D.G., MacLean, B.C.Proterozoic thick-skinned intracratonic deformation, Colville Hills Northwest Territories, CanadaGeology, Vol. 20, No. 1, January pp. 67-70Northwest TerritoriesGeophysics -seismics, Reflections, stratigraphy
DS1992-0978
1992
Maclean, B.C.Maclean, B.C., Cook, D.G.The influence of Proterozoic structures on the development of Laramidestructures, northern interior Plains, Northwest Territories, CanadaCanadian Petroleum Geologists Bulletin, Vol. 40, No. 3, September pp. 207-221Northwest TerritoriesStructure, Interior Plains
DS1995-0347
1995
Maclean, B.C.Cook, D.G., Maclean, B.C.The intracratonic Paleoproterozoic Forward orogeny, and implications for regional correlations, northwest Territories.Canadian Journal of Earth Sciences, Vol. 32, No. 11, Nov. pp. 1991-1998Northwest TerritoriesOrogeny, Structure, tectonics
DS1996-0291
1996
Maclean, B.C.Cook, D.G., Maclean, B.C.Mid-continent tectonic inversions, Northwest Territories, CanadaJournal of Structural Geology, Vol. 18, No. 6, June 1, pp. 791-802.Northwest TerritoriesTectonics
DS2002-0978
2002
Maclean, B.C.Maclean, B.C., Miles, W.Potential field modeling of a Proterozoic half graben near Blackwater Lake: and its implications Fort SimpsonCanadian Journal of Earth Science, Vol.39,2,Feb.169-87.Northwest TerritoriesGeophysics - magnetics, seismics, Precambrian tectonics
DS2002-1096
2002
Maclean, B.C.Morrow, D., Maclean, B.C., Tzeng, P., Pana, D.Subsurface Paleozoic structure and isopach maps and selected seismic surveys ofGeological Survey of Canada Open File, No. 4366, 1 CD., $26.Northwest Territories, AlbertaGeophysics - seismics
DS200412-0356
2004
Maclean, B.C.Cook, D.G., Maclean, B.C.Subsurface Proterozoic stratigraphy anf tectonics of the western plains of the Northwest Territories.Geological Survey of Canada Bulletin, No. 575 92p. 1 CD $ 70.Canada, Northwest TerritoriesTectonics
DS200412-1192
2004
MacLean, B.C.MacLean, B.C., Cook, D.G.Revisions to the Paleoproterozoic sequence A, based on reflected seismic dat a across the western plains of the Northwest TerritoPrecambrian Research, Vol. 129, 3-4, March 10, pp. 271-289.Canada, Northwest TerritoriesGeophysics - seismics
DS1992-0979
1992
Maclean, D.Maclean, D., Adams, C.Diamonds in Canada odds of finding a mine are long, but favourable forWood Gundy Investment Research, June 24, 5pCanada, Northwest TerritoriesNews item, Promotional literature -background
DS1991-0761
1991
MacLean, W.H.Ichangi, D.W., MacLean, W.H.The Archean volcanic facies in the Migori segment, Nyanza greenstone @Kenya: stratigraphy, geochemistry and mineralizationJournal of African Earth Sciences, Vol. 13, No. 3-4, pp. 277-290KenyaGreenstone belt -Nyanza, Mineralization
DS1992-0977
1992
Maclean HunterMaclean HunterSurface Mining, second editionNaclean Hunter, M-164, 2nd ed, approx. $ 80.00 United States plus $ 34.50 airmailGlobalBook -ad, Surface Mining
DS200812-0697
2008
MacLeansMacLeansA shiny piece of hope. Birks sells diamonds and a little peace of mind.Macleans Magazine, No. 24, June 23, p. 38.Canada, United StatesNews item - retail
DS200512-0670
2005
Macleans MagazineMacleans MagazinePixels, not pickaxes. Brief overview of Geoinformatics and Goldcorp background.Macleans Magazine, August 1, pp. 36-37.Canada, OntarioComputer - brief overview
DS2001-0715
2001
Maclennan, J.Maclennan, J., McKenzie, D., Gronvold, K., Slater, L.Crustal accretion under northern IcelandEarth and Planetary Science Letters, Vol. 191, No. 3-4, pp. 295-310.GlobalTectonics, geodynamics
DS2001-0716
2001
Maclennan, J.Maclennan, J., McKenzie, D.M., Gronvold, K.Plume driven upwelling under central IcelandEarth and Planetary Science Letters, Vol. 194, No. 1-2, pp. 67-82.IcelandHot spots, Herdubreid region, Northern Volcanic Zone
DS2002-0979
2002
Maclennan, J.Maclennan, J., Lovell, B.Control of regional sea level by surface uplift and subsidence caused by magmatic underplating of Earth's crust.Geology, Vol.30,8,Aug.pp.675-8.MantleMagmatism
DS200612-0646
2005
Maclennan, J.Jones, S.M., Maclennan, J.Crustal flow beneath Iceland.Journal of Geophysical Research, Vol. 110, B9 B09410Europe, IcelandTectonics
DS201112-0813
2011
Maclennan, J.Poore, H., White, N., Maclennan, J.Ocean circulation and mantle melting controlled by radial flow of hot pulses in the Iceland plume.Nature Geoscience, in press availableMantle, Europe, IcelandMelting
DS201112-0887
2011
Maclennan, J.Rudge, J.F., Maclennan, J., Stracke, A.Statistical sampling of mantle heterogeneity.Goldschmidt Conference 2011, abstract p.1765.MantleMelting
DS201312-0756
2013
Maclennan, J.Rudge, J.F., Maclennan, J., Stracke, A.The geochemical consequences of mixing melts from a heterogeneous mantle.Geochimica et Cosmochimica Acta, Vol. 114, pp. 112-143.MantleMelting
DS201412-0464
2014
Maclennan, J.Klocking, M., White, N., Maclennan, J.A magmatic probe of lithospheric thickness variations beneath western North America.Volcanic and Magmatic Studies Group meeting, Poster Held Jan. 6-8. See minsoc websiteUnited States, CanadaMagmatism
DS201610-1875
2016
Maclennan, J.Jennings, E.S., Gibson, S.A., Maclennan, J., Heinonen, J.S.Deep mixing of mantle melts beneath continental flood basalt provinces: constraints from olivine hosted melt inclusions in primitive magmas. Etendeka and KarooGeochimica et Cosmochimica Acta, in press availableAfrica, NamibiaPicrite, ferroPicrite

Abstract: We present major and trace element compositions of 154 re-homogenised olivine-hosted melt inclusions found in primitive rocks (picrites and ferropicrites) from the Mesozoic Paraná-Etendeka and Karoo Continental Flood Basalt (CFB) provinces. The major element compositions of the melt inclusions, especially their Fe/Mg ratios, are variable and erratic, and attributed to the re-homogenisation process during sample preparation. In contrast, the trace element compositions of both the picrite and ferropicrite olivine-hosted melt inclusions are remarkably uniform and closely reflect those of the host whole-rocks, except in a small subset affected by hydrothermal alteration. The Paraná-Etendeka picrites and ferropicrites are petrogenetically related to the more evolved and voluminous flood basalts, and so we propose that compositional homogeneity at the melt inclusion scale implies that the CFB parental mantle melts were well mixed prior to extensive crystallisation. The incompatible trace element homogeneity of olivine-hosted melt inclusions in Paraná-Etendeka and Karoo near primitive magmatic rocks has also been identified in other CFB provinces and contrasts with findings from studies of basalts from mid-ocean ridges (e.g. Iceland and FAMOUS on the Mid Atlantic Ridge), where heterogeneity of incompatible trace elements in olivine-hosted melt inclusions is much more pronounced. We suggest that the low variability in incompatible trace element contents of olivine-hosted melt inclusions in near-primitive CFB rocks, and also ocean island basalts associated with moderately thick lithosphere (e.g. Hawaii, Galápagos, Samoa) may reflect mixing along their longer transport pathways during ascent and/or a temperature contrast between the liquidus and the liquid when it arrives in the crust. These thermal paths promote mixing of mantle melts prior to their entrapment by growing olivine crystals in crustal magma chambers. Olivine-hosted melt inclusions of ferropicrites from the Paraná-Etendeka and Karoo CFB have the least variable compositions of all global melt inclusion suites, which may be a function of their unusually deep origin and low viscosity.
DS201611-2115
2016
Maclennan, J.Jennings, E.S., Gibson, S.A., Maclennan, J., Heinonen, J.S.Deep mantle melts beneath continental flood basalt provinces: constraints from olivine hosted melt inclusions in primitive magmas.Geochimica et Cosmochimica Acta, Vol. 196, pp. 36-57.Africa, Namibia, AngolaParan-Etendeka, Karoo

Abstract: We present major and trace element compositions of 154 re-homogenised olivine-hosted melt inclusions found in primitive rocks (picrites and ferropicrites) from the Mesozoic Parana ´-Etendeka and Karoo Continental Flood Basalt (CFB) provinces. The major element compositions of the melt inclusions, especially their Fe/Mg ratios, are variable and erratic, and attributed to the re-homogenisation process during sample preparation. In contrast, the trace element compositions of both the picrite and ferropicrite olivine-hosted melt inclusions are remarkably uniform and closely re?ect those of the host whole-rocks, except in a small subset a?ected by hydrothermal alteration. The Parana ´-Etendeka picrites and ferropicrites are petrogenet- ically related to the more evolved and voluminous ?ood basalts, and so we propose that compositional homogeneity at the melt inclusion scale implies that the CFB parental mantle melts were well mixed prior to extensive crystallisation. The incompatible trace element homogeneity of olivine-hosted melt inclusions in Parana ´-Etendeka and Karoo primitive magmatic rocks has also been identi?ed in other CFB provinces and contrasts with ?ndings from studies of basalts from mid- ocean ridges (e.g. Iceland and FAMOUS on the Mid Atlantic Ridge), where heterogeneity of incompatible trace elements in olivine-hosted melt inclusions is more pronounced. We suggest that the low variability in incompatible trace element contents of olivine-hosted melt inclusions in near-primitive CFB rocks, and also ocean island basalts associated with moderately thick lithosphere (e.g. Hawaii, Gala ´pagos, Samoa), may re?ect mixing along their longer transport pathways during ascent and/or a temperature contrast between the liquidus and the liquid when it arrives in the crust. These thermal paths promote mixing of mantle melts prior to their entrapment by growing olivine crystals in crustal magma chambers. Olivine-hosted melt inclusions of ferropicrites from the Parana ´-Etendeka and Karoo CFB have the least variable compositions of all global melt inclusion suites, which may be a function of their unusually deep origin and low viscosity.
DS201704-0629
2017
Maclennan, J.Jennings, E.S., Holland, T.J.B., Maclennan, J., Gibson, S.A.The composition of melts from a heterogeneous mantle and the origin of ferropicrite: application of a thermodynamic model.Journal of Petrology, Vol. 57, 11-12, pp. 2289-2310.MantleGeochemistry
DS201809-2072
2018
Maclennan, J.Matthews, S., Shorttle, O., Maclennan, J., Rudge, J.F., Miller, W.G.R.Can we detect carbon rich mantle reservoirs?Goldschmidt Conference, 1p. AbstractMantlecarbon

Abstract: The Earth’s surface inventory of carbon is critical for maintaining the planet’s habitability, yet the majority of Earth’s carbon is likely sequestered in the solid Earth. Understanding how Earth’s shallow carbon cycle evolved requires an assesment of the total carbon accreted, how it was distributed between Earth’s reservoirs, and how these reservoirs continue to exchange carbon. The low carbon content of Earth’s depleted upper mantle has been well constrained by primitive olivine hosted melt inclusions and the CO2/3He ratios of magmatic fluids. Using mass balance constraints we show that either the lower mantle is considerably more carbon rich, or the Earth has lost much of its initial carbon inventory. Distinguising between these scenarios is crucial for understanding the development and maintenance of Earth’s shallow carbon cycle. We assess the carbon content of the lower mantle using new melt inclusion datasets from Iceland, sampling both primordial and recycled mantle material. By comparing carbon concentrations with lithophile element concentrations we find evidence that carbon rich material is transported in the Iceland plume. Furthermore, we demonstrate that such datasets provide only a low bound on the true carbon content of the lower mantle, due to fundamental limits imposed by magma mixing, degassing and inclusion decrepitation. Using a global compilation of melt inclusion analyses we argue these processes occur ubiquitously and are likely to limit our ability to robustly resolve high mantle carbon using melt inclusion datasets. By combining these observations with global mass balance constraints we derive new estimates of the carbon content of primordial and recycled mantle material.
DS1997-0712
1997
MacLeod, C.J.MacLeod, C.J., Tyler, P.A., Walker, C.L.Tectonic, magmatic, hydrothermal and biological segmentation of Mid-OceanRidgesGeological Society of London Special Paper, No. 118, 240p. approx. 200.00GlobalTectonics, Book - Table of contents
DS200412-0355
2004
MacLeod, C.J.Coogan, L.A., Thompson, G.M., MacLeod, C.J., Dick, H.J., Edwards, S.J., Hosford Scierer, A., Barry, T.L.A combined basalt and peridotite perspective on 14 million years of melt generation at the Atlantis Bank segment of the southwesChemical Geology, Vol. 207, 1-2, pp. 13-30.IndiaMantle dynamics, tectonics
DS1992-1630
1992
MacLeod, M.D.Walstrom, J.S., MacLeod, M.D., Rutherford, T.L.Environmental liability management for mineral processorsAmerican Institute of Mining, Metallurgical, and Petroleum Engineers (AIME) Preprint, Annual Meeting held Phoenix Arizona Feb. 24-27th. 1992, Preprint No. 92-16. 5pGlobalEnvironment, Legal, mineral processing
DS1981-0277
1981
Macleod, N.Macleod, N.Mining in Western AustraliaPerth: Chamber of Mines of Western Australia., 73P.AustraliaMining Overview, Diamonds
DS1991-1033
1991
MacLeod, N.MacLeod, N., Keller, G.Hiatus distributions and mass extinctions at the Cretaceous/TertiaryboundaryGeology, Vol. 19, No. 5, May pp. 497-501GlobalBoundary, Extinctions
DS201912-2821
2019
Macleod, S.Sanatmaria-Perez, D., Ruiz-Fuertes, J., Pena-Alvarez, M., Chulia-Jordan, R., Marquerno, T., Zimmer, D., Guterrez-Cano, V., Macleod, S., Gregoryanz, E., Popescue, C., Rodriguez-Herandez, P., Munoz, A.Post-tilleyite, a dense calcium silicate carbonate phase.Nature Scientific Reports, Vol. 9, 11p. PdfMantletilleyite

Abstract: Calcium carbonate is a relevant constituent of the Earth’s crust that is transferred into the deep Earth through the subduction process. Its chemical interaction with calcium-rich silicates at high temperatures give rise to the formation of mixed silicate-carbonate minerals, but the structural behavior of these phases under compression is not known. Here we report the existence of a dense polymorph of Ca5(Si2O7)(CO3)2 tilleyite above 8 GPa. We have structurally characterized the two phases at high pressures and temperatures, determined their equations of state and analyzed the evolution of the polyhedral units under compression. This has been possible thanks to the agreement between our powder and single-crystal XRD experiments, Raman spectroscopy measurements and ab-initio simulations. The presence of multiple cation sites, with variable volume and coordination number (6-9) and different polyhedral compressibilities, together with the observation of significant amounts of alumina in compositions of some natural tilleyite assemblages, suggests that post-tilleyite structure has the potential to accommodate cations with different sizes and valencies.
DS1960-1160
1969
Macleod, W.N.Macleod, W.N.Intrusive Carbonate Rocks of the Mount Fraser Area, Peak Hill Goldfield.Western Australia Department of Mines Report For 1969, PP. 26-29.Australia, Western AustraliaCarbonatite
DS200712-1177
2006
MacMaster, G.Woodward, R., MacMaster, G., Scott, F.Ekati - drilling in the Canadian Arctic - a journey of continuous safety improvements.34th Yellowknife Geoscience Forum, p. 60-61. abstractCanada, Northwest TerritoriesEkati - safety
DS200912-0142
2009
Macmbira, M.J.B.Da Silva Valerio, C., da Silva Valerio, V., Macmbira, M.J.B.The 1.90-1.88 Ga magnetism in the southernmost Guyana Shield, Amazonas, Brazil: geology, geochemistry, zircon geochronology and tectonic implications.Journal of South American Earth Sciences, Vol. 28, 3, pp. 304-320.South America, BrazilGeochronology
DS201805-0960
2017
Macmillan, H.Macmillan, H.Mining in South Africa in the last 30 years - an overview.Reviews of African Political Economy, Vol. 44, 152, pp. 272-291.Africa, South Africahistory

Abstract: This article examines the history of South African mining over the last 30 years. It notes the declining contribution of mining to the economy, and a drop in employment levels and labour migration. It considers political, legislative and macro-economic changes, as well as mine ownership and control. It addresses the question why a democratically elected government, progressive labour legislation, trade-unionisation and Black Economic Empowerment have made remarkably little difference to working conditions. After examining the trajectories of individual commodities, such as gold, platinum, coal and diamonds, it concludes there has been no fundamental change in the relationship between state and capital.
DS1970-0128
1970
Macmillan, M.Macmillan, M.Sir Henry Barkly, Mediator and Moderator 1815- 1898Cape Town: A.a. Balkema., 302P.South AfricaKimberley, Biography
DS1900-0341
1905
Macmillan And FergusonMacmillan And FergusonThe Orange River Colony. an Illustrated Historical Description and Commercial Review.Cape Town, Port Elizabeth: Macmillan And Ferguson., 51P.Africa, South AfricaMineral Resources, Current Activities, Diamond Occurrences
DS201812-2845
2018
Macmorran, M.Macmorran, M.2018 kimberlite discoveries at the Loki ( Lac de Gras, NT) and Mel ( Melville Peninsula, NU) diamond projects.2018 Yellowknife Geoscience Forum , p. 49. abstractCanada, Northwest Territories, Nunavutdeposit - Loki, Mel

Abstract: Details will be provided on the recent kimberlite discoveries at North Arrow's Loki (NT) and Mel (NU) diamond projects. In April of this year, North Arrow announced the discovery of a new kimberlite at its Loki Diamond Project in the Northwest Territories. The Project is located in the Lac de Gras region, approximately 30 km southwest, and 24 km west of the Ekati and Diavik diamond mines, respectively. The Loki claims are contiguous to the south and east of the diamondiferous Monument kimberlite cluster. The project hosts several prospective exploration targets, as well as five known kimberlites: EG-01, EG-02, EG-05 and EG-130. At the beginning of March 2018, North Arrow commenced drilling to test the EG-05 kimberlite, as well as other priority targets. On April 5th, intersections of the first new kimberlite (465) discovered at Lac de Gras in over five years were announced, along with new drilling of kimberlite EG-05. The Mel Diamond Project is located on the Melville Peninsula (NU), approximately 140 km south of the community of Hall Beach, and 210 km northeast of the community of Naujaat (formerly Repulse Bay). A prospecting program conducted in late 2017 focused on discovery of potential kimberlite bedrock sources to a well-defined kimberlite indicator mineral train in the north part of the project area. Kimberlite float and subcrop was found in two areas, including a surface exposure of the ML8 kimberlite. A 62.1 kg sample of ML8 yielded 23 diamonds larger than the 0.106 mm sieve size, including a single, colourless diamond larger than the 0.85 mm sieve size. The 2018 exploration program included 778 m of exploration drilling leading to the discovery of a new kimberlite (ML345) and defining the ML8 kimberlite over a 170 m strike length. In addition, 447 till samples were collected to better define existing and new targets within the project area, 14 magnetic ground survey grids were completed, and over 200 kg of kimberlite was collected from surface at ML8 for further microdiamond analysis.
DS1991-1945
1991
Macnab, R.Zonenshain, L.P., Verhoef, J., Macnab, R., Meyers, H.Magnetic imprints of continental accretion in the U.S.S.REos, Vol. 72, No. 29, July 16, pp. 305, 310RussiaGeophysics -magnetics, Tectonics
DS1995-1137
1995
Macnab, R.Macnab, R., Verhoef, J., Roest, W., Arkani-Hamed, J.New database documents the magnetic character of the Arctic and NorthAtlanticEos, Vol. 76, No. 45, Nov. 7, p. 449, 458Arctic, Atlantic OceanGeophysics - database
DS1991-1034
1991
MacNae, J.MacNae, J., McGowan, P.Quantitative resistance and capacitative electrodes: new developments in inductive source resistivity8th. Australian Society of Exploration Geophysicists (ASEG) Conference, Vol. 22, No. 2, June pp. 251-256AustraliaGeophysics, Inductive resistivity
DS1995-1138
1995
Macnae, J.Macnae, J.Applications of geophysics for the detection and exploration of Kimberlites and lamproites.Journal of Geochemical Exploration, Vol. 52, pp. 213-244.AustraliaDiamond exploration, Geophysics
DS1995-1139
1995
Macnae, J.Macnae, J.Esoteric and mundane geophysics for Diamondiferous pipe explorationExploration Geophysics, Vol. 26, No. 2-3, June 1, pp. 131-137.AustraliaGeophysics, Diamonds
DS201610-1885
2016
Macnae, J.Macnae, J.Definitive superparamagnetic source identification through spatial, temporal, and amplitude analysis of airborne electromagnetic data.Geophysical Prospecting, in press available 14p.TechnologyPaleosols

Abstract: The aim of this paper is to add confidence to existing methods using decay shape analysis to detect superparamagnetic responses in airborne electromagnetic data. While expensive to acquire, vertical spatial gradient measurements of the electromagnetic signals can discriminate near-surface superparamagnetic sources. This research investigated the use of horizontal spatial gradients and amplitude information as further indicators of superparamagnetic. High horizontal gradients were shown both theoretically and in field data to help discriminate superparamagnetic from deep mineral targets. Further, superparamagnetic responses have characteristically small amplitudes inconsistent with realistic mineral exploration targets at shallow depths.
DS201703-0425
2016
Macnae, J.Macnae, J.Airborne unmanned excluding photography. RPA geophysics .Society of Exploration Geophysics, Dallas annual meeting, RMIT University 27ppt.TechnologyGeophysics
DS201705-0852
2016
Macnae, J.Macnae, J.DO-27 and DO-18 (formerly Tli Kwi Cho complex when they were believed to be part of the same kimberlite complex).SEG Annual Meeting Dallas, 24 ppt.Canada, Northwest TerritoriesDeposit - Tli Kwi Cho
DS1975-0800
1978
Macnae, J.C.Macnae, J.C.Kimberlite GeophysicsEos, Vol. 59, No. 12, P. 1023, (abstract.).Lesotho, South AfricaKimberlite, Geophysics
DS1975-1122
1979
Macnae, J.C.Macnae, J.C.Kimberlites and Exploration GeophysicsGeophysics, Vol. 44, No. 8, PP. 1395-1416.Lesotho, South AfricaKimberlite, Geophysics
DS1989-0060
1989
Macnae, J.C.Bailey, R.C., Craven, J.A., Macnae, J.C., Polzar, B.D.Deep UTEM controlled source electromagnetic sounding across the Ivanhoe Lake cataclastic zoneGeological Association of Canada (GAC) Annual Meeting Program Abstracts, Vol. 14, p. A124. (abstract.)OntarioTectonics, Kapuskasing Zone
DS1989-0061
1989
Macnae, J.C.Bailey, R.C., Craven, J.A., Macnae, J.C., Polzer, B.D.Imaging of deep fluids in Archean crustNature, Vol. 340, No. 6229, July 13, pp. 136-8 Database #18038OntarioGeophysics, Midcontinent- Ivanhoe Lake
DS200612-0706
2006
MacNeil, D.Kjarsgaard, B.A., Harvey, S.E., Zonneveld, J.P., Heaman, L.M., White, D., MacNeil, D.Volcanic stratigraphy, eruptive sequences and emplacement of the 140/141 kimberlite Fort a la Corne field, Saskatchewan.Emplacement Workshop held September, 5p. extended abstractCanada, SaskatchewanDeposit - 140/141 geology
DS1985-0030
1985
Macneil, K.A.Averill, S.A., Macneil, K.A., Huneault, R.G., Baker, C.L.Rotasonic drilling operations and overburden heavy mineral studies Matheson area, district of CochraneOntario Geological Survey Open File, No. 5569, 59p. 5 figs. 1 mapOntarioDrilling, Geochemistry, Sampling, Geomorphology
DS1975-0557
1977
Macnevin, A.A.Macnevin, A.A.Diamonds in New South Wales. #1New South Wales Geological Survey Min. Res., No. 42, 114P.AustraliaKimberlite, Prospecting
DS1980-0222
1980
Macnevin, A.A.Macnevin, A.A., Holmes, G.G.Gemstones; New South Wales Geological Survey, 1980New South Wales Geological Survey Mineral Industry Report., No. 18, 119P.Australia, New South WalesKimberley, Diamond Occurrences
DS200912-0224
2009
MacNiocaill, C.Fontana, G.P.,MacNiocaill, C., Brown, R.J., Sparks, S.R., Field, M., Gernon, T.M.Emplacement temperatures of pyroclastic and colcaniclastic deposits in kimberlite pipes in southern Africa: new constraints from paleomagnetic measurementsGAC/MAC/AGU Meeting held May 23-27 Toronto, Abstract onlyAfrica, Botswana, South AfricaDeposit - AK1, Orapa, K1, K2 Venetia
DS201212-0092
2012
MacNiocaill, C.Brown, R.J., Manya, S., Buisman, I., Fontana, G., Field, M., MacNiocaill, C., Sparks, R.S.J., Stuart, F.M.Eruption of kimberlite magmas: physical volcanology, geomrphology and age of the youngest kimberlitic volcanoes known on Earth ( the Upper Pleistocene-Holocene Igwisi Hills, volcanoes, Tanzania.Bulletin of Volcanology, Vol. 74, 7, pp. 1621-1643.Africa, TanzaniaIgwisi Hills
DS1999-0443
1999
MacNiocaill C.Marcano, M.C., Van Der Voo, R., MacNiocaill C.True polar wander during the Permo-TriassicJournal of Geodynamics, Vol. 28, No. 2-3, Sept. 2, pp. 75-95.MantleGeophysics - thermodynamics, Lithosphere
DS200512-0090
2005
Maconachie, R.Binns, T., Maconachie, R.Going home in post-conflict Sierra Leone: diamonds, agriculture and re-building rural livelihoods in the eastern province.Geography, Vol. 90, 1, pp. 67-78. Ingenta 1050887072Africa, Sierra LeoneInfostructure
DS200712-0664
2007
MaConachie, R.MaConachie, R., Binns, T.Farming miners or mining farmers? Diamond mining and rural development in post conflict Sierra Leone.Journal of Rural Studies, Vol. 23, 3, pp. 367-380.Africa, Sierra LeoneHistory
DS200712-0665
2007
MaConachie, R.MaConachie, R., Binns, T.Farming miners or mining farmers? Diamond mining and rural development in post conflict Sierra Leone.Journal of Rural Studies, Vol. 23, 3, pp. 367-380.Africa, Sierra LeoneHistory
DS200912-0464
2009
Maconachie, R.Maconachie, R.Diamonds, governance and 'local' development in post-conflict Sierra Leone: lessons for artisanal and small scale mining in sub-Saharan Africa?Resources Policy, Vol. 34, 1-2, pp. 71-79.Africa, Sierra LeoneLegal
DS201603-0398
2016
Maconachie, R.Maconachie, R., Hilson, G.Re-thinking the child labour "problem" in rural sub-Saharan Africa: the case of Sierra Leone's half shovels.World Development, Vol. 78, pp. 136-147.Africa, Sierra LeoneHistory

Abstract: This article contributes to evolving debates on Sierra Leone’s post-war “crisis of youth” by providing an extended analysis of the role that young boys and girls assume in negotiating household poverty and enhancing their livelihood opportunities in small-scale mining communities. Child miners – or “half shovels” as they are locally known – are both directly and indirectly involved in small-scale gold extraction in Kono District, Sierra Leone’s main diamond-producing area. But the implications of their involvement are often far more nuanced and complex than international children’s rights advocates understand them to be. Drawing upon recent fieldwork carried out in and around the Kono mining village of Bandafayie, the article argues that children’s participation in the rural economy not only generates much-needed household income, but in many cases is the only way in which they can earn the monies needed to attend school. A blind and uncritical acceptance of international codes and agreements on child labor could have an adverse impact on children and, by extension, poor communities in rural Sierra Leone. Western notions of “progress” and development, as encapsulated in the post-conflict reconstruction programing of international NGOs and donor organizations, often do not match up with the complex realities or competing visions of local people.
DS201810-2350
2018
Maconachie, R.Maconachie, R., Hilson, G.The war whose bullets you don't see: diamond digging, resilience and ebola in Sierra Leone.Journal of Rural Studies, Vol. 61, 1, pp. 110-122.Africa, Sierra Leonealluvials

Abstract: This paper reflects critically on the transformational impacts the recent Ebola epidemic has had in diamond-rich areas of rural Sierra Leone. It focuses specifically on the country's ‘diggers’, a sizable group of labourers who occupy the bottom of the country's artisanal diamond mine production pyramid. Based upon research conducted in the diamond-producing localities of Kenema and Kono, the paper argues how, in sharp contrast to the gloomy picture painted in the literature about their existences and struggles, diggers exhibited considerable resilience during the Ebola crisis. Their diversified livelihood portfolios proved to be effective survival strategies and buffers against the shocks and stresses brought about by lengthy periods of quarantine, and during times when mobility was restricted by the government in a bid to prevent the spreading of the disease. Drawing inspiration from the resilience literature, the paper captures the essence of these survival strategies, which should be viewed as latest reshuffling and expansion of diggers' rural livelihood portfolios. Policymakers and donors have yet to embrace fully these changes in a country where the Ebola recovery period promises to be lengthy and at a time when fresh, locally-informed rural development solutions are in short supply.
DS202011-2051
2020
Maconachie, R.Maconachie, R., Conteh, F.M.Artisanal mining and the rationalisation of informality: critical reflections from Liberia.Canadian Journal of Development Studies, Vol. 41, 3, pp. 432-449. pdfAfrica, Liberiaalluvials

Abstract: Across sub-Saharan Africa, artisanal and small-scale mining (ASM) represents a major source of direct and indirect employment. Yet, despite the livelihood benefits and the growing interest from governments, donors and policy makers to formalise ASM, most artisanal miners still operate informally. Focusing on Liberia, this article critically investigates the question of why formalisation efforts continue to fail and argues that the persistence of informality in the sector needs to first be understood as a rational strategy for those who profit from it. Only then can sustainable mining reforms be linked to broader national and international extractive sector policy frameworks.
DS201504-0226
2015
Macorps, E.Valentine, G.A., Graettinger, A.H, Macorps, E., Ross, P-S., White, J.D.L., Dohring, E., Sonder, I.Experiments with vertically and laterally migrating subsurface explosions with applications to the geology of phreatomagmatic and hydrothermal explosion craters and diatremes.Bulletin of Volcanology, Vol. 77, 15p.TechnologyDiatremes, kimberlites
DS2003-0858
2003
Macouin, M.Macouin, M., Valet, J.P., Besse, J., Buchan, K., Ernst, R., Le Goff, M., ScharerLow paleointensities recorded in 1 to 2.4. Ga Proterozoic dykes, Superior ProvinceEarth and Planetary Science Letters, Vol. 213, 1-2, pp. 79-95.Ontario, ManitobaGeochronology
DS200412-1193
2003
Macouin, M.Macouin, M., Valet, J.P., Besse, J., Buchan, K., Ernst, R., Le Goff, M., Scharer, U.Low paleointensities recorded in 1 to 2.4. Ga Proterozoic dykes, Superior Province, Canada.Earth and Planetary Science Letters, Vol. 213, 1-2, pp. 79-95.Canada, Ontario, ManitobaGeochronology
DS200612-0847
2006
Macouin, M.Macouin, M., Valet, J.P., Besse, J., Ernst, R.E.Absolute paleointensity at 1.27 Ga from the Mackenzie dyke swarm ( Canada).Geochemistry, Geophysics, Geosystems: G3, Vol. 7, Q01H21Canada, Northwest TerritoriesGeochronology, magnetiziation
DS200912-0143
2009
MacPhersonDale, C.W., Pearson, D.G., Starkey, N.A., Stuart, F.M., Ellam, Larsen, Fitton, MacPhersonOsmium isotope insights into high 3He4He mantle and convecting mantle in the North Atlantic.Goldschmidt Conference 2009, p. A260 Abstract.Canada, Nunavut, Baffin Island, Europe, GreenlandPicrite
DS1992-0980
1992
Macpherson, C.Macpherson, C., Mattey, D.P., Harris, J.Oxygen isotope analysis of microgram quantities of silicate by a laser fluorination technique dat a for syngenetic inclusions in diamondV.m. Goldschmidt Conference Program And Abstracts, Held May 8-10th. Reston, p. A 66. abstractGlobalDiamond inclusions, Geochemistry
DS1994-1124
1994
Macpherson, C.Mattey, D., Lowry, D., Macpherson, C.Oxygen isotope composition of mantle peridotiteEarth Planetary Science Letters, Vol. 128, No. 3-4, Dec. pp. 231-242.MantleGeochronology
DS1994-1060
1994
Macpherson, C.G.Lowry, D., Mattey, D.P., Macpherson, C.G., Harris, J.W.Evidence for stable isotope and chemical disequilibrium associated with diamond formation in the mantle.Mineralogical Magazine, Vol. 58A, pp. 535-536. AbstractMantleGeochronology, Diamond genesis
DS2002-0980
2002
Macpherson, C.G.Macpherson, C.G., Hall, R.Timing and tectonic controls in the evolving orogen of SE Asia and the western Pacific and some implications for ore generation.Geological Society of London Special Publication, No. 204, pp.49-68.AsiaTectonics - not specific to diamonds
DS200512-0220
2005
MacPherson, C.G.Day, J.M.D., Hilton, D.R., Pearson, D.G., MacPherson, C.G., Kjarsgaard, B.A., Janney, P.E.Absence of a high time integrated 3He (U-Th) source in the mantle beneath continents.Geology, Vol. 33, 9, Sept. pp. 733-736.Mantle, Canada, Africa, South Africa, UgandaGeochronology - helium isotopes
DS200512-0671
2005
MacPherson, C.G.MacPherson, C.G., Hilton, D.R., Day, J.M., Lowry, D., Grenvold, K.High 3He 4He depleted mantle and low 180 recycled oceanic lithosphere in the source of central Iceland magmatism.Physics and Planetary Science Letters, Vol. 233, 3-4, pp. 411-427.MantleGeochemistry
DS200512-0672
2005
MacPherson, C.G.MacPherson, C.G., Hilton, D.R., Day, J.M.D., Lowry, D., Gronvold, K.High He3 He4 depleted mantle and low delta18O recycled oceanic lithosphere in the source of central Iceland magmatism.Earth and Planetary Science Letters, Vol. 233, 3-4, May 15, pp. 411-427.Europe, IcelandMagmatism, geochronology, recycling
DS200912-0161
2009
Macpherson, C.G.Day, J.M.D., Pearson, D.G., Macpherson, C.G., Lowry, D., Carracedo, J-C.Pyroxenite rich mantle formed by recycled oceanic lithosphere: oxygen osmium isotope evidence from Canary Island lavas.Geology, Vol. 37, 6, pp. 555-558.Mantle, Canary IslandsGeochronology
DS201212-0641
2012
MacPherson, C.G.Shaw, A.M., Hauri, E.H., Behn, M.D., Hilton, D.R., MacPherson, C.G., Sinton, J.M.Long term preservation of slab signatures in the mantle interred from hydrogen isotopes.Nature Geoscience, Vol. 5, March pp, 224-228.MantleTomography - seismics
DS200512-0092
2004
Macpherson, G.L.Blackburn, T.J., Stockli, D., Berendsen, P., Carlson, R.W., Macpherson, G.L.New (U-TH/He) age constraints on the emplacement of kimberlite pipes in north eastern Kansas.Geological Society of America Annual Meeting ABSTRACTS, Nov. 7-10, Paper 192-2, Vol. 36, 5, p. 447.United States, KansasGeochronology, Bala. Stockdale, Tuttle, Leonardville
DS1982-0385
1982
Macquarie UniversityMacquarie UniversityThe Magsat Project in AustraliaNational Technical Information Service, NASA CR 169599, 8P.AustraliaGeophysics
DS201012-0679
2010
MacQueen, J.Seigel, H.O., Nind, C.J.M., Milanov, A., MacQueen, J.Results from the initial field tests of a borehole gravity meter for mining and geotechnical applications. NOT specific to diamonds.Scintrex, 5p. distributed Jan. 2010 PPT also availableTechnologyGravity methodology
DS1992-0981
1992
Macqueen, R.W.Macqueen, R.W., Leckie, D.A.Foreland basins and foldbeltsAmerican Association of Petroleum Geologists, Memoir 55, 460pCordilleraBook -ad, Basins
DS1997-0713
1997
MacQueen, R.W.MacQueen, R.W.Exploring for minerals in Alberta: Geological Society of Canada (GSC) Alberta agreement on mineral development 1992-1995Geological Survey of Canada Bulletin, No. 500, 350pAlbertaBook - table of contents, Mineral resources
DS200912-0795
2009
MacQuet, A.Verhoeven, O., MacQuet, A., Vacher, P., Rivoldini, A., Menvielle, M., Arrial, P.A., Chiblet, G., Tarits,P.Constraints on thermal state and composition of the Earth's lower mantle from electromagnetic impedances and seismic data.Journal of Geophysical Research, Vol. 114, B3, B03302.MantleGeophysics - seismics
DS2003-0276
2003
MacRae, C.M.Cooper, S.A., MacRae, C.M., Wilson, N.C., Scarlett, N.V.Y., Marx, W.T.Diamond coatings that affect diamond recoveries on grease tables investigated by8ikc, Www.venuewest.com/8ikc/program.htm, Session 1 POSTER abstractSouth AfricaKimberlite geology and economics, Technology - recovery, Perdevlei, Kareevlei
DS201312-0564
2013
MacRae, C.M.MacRae, C.M., Wilson, N.C., Torpy, A.hyper spectral cathodluminescence.Mineralogy and Petrology, in pressTechnologyCL spectra
DS1960-1161
1969
Macrae, N.D.Macrae, N.D.Ultramafic Inclusions of the Abitibi Area, OntarioCanadian Journal of Earth Sciences, Vol. 6, pp. 281-303.OntarioUltramafic Rocks, Peridotites
DS1990-1127
1990
MacRae, N.D.O'Connor, T.K., MacRae, N.D.A new occurrence of Rhoenite in a lherzolite xenolithof Victoria, AustraliaGeological Association of Canada (GAC)/Mineralogical Association of Canada (MAC) Vancouver 90 Program with Abstracts, Held May 16-18, Vol. 15, p. A98. AbstractAustraliaMt. Leura, Lherzolite xenolith
DS1993-0404
1993
MacRae, N.D.Elphick, J.R., MacRae, N.D., Barnett, R.L., Barron, K.M., Morris, W.Spinel compositions and trends from tuffisitic breccias of the James BayLowlands, OntarioMid-continent diamonds Geological Association of Canada (GAC)-Mineralogical Association of Canada (MAC) Symposium ABSTRACT volume, held Edmonton May, pp. 47-52OntarioMineralogy
DS1994-1083
1994
MacRae, N.D.MacRae, N.D., Armitage, A.E., Miller, A.R.Diamond bearing potential of alkaline dykes in the Gibson Lake area, District of Keewatin, northwest Territories.Geological Association of Canada (GAC) Abstract Volume, Vol. 19, p.Northwest TerritoriesAlkaline dykes, Gibson Lake area
DS1995-0891
1995
MacRae, N.D.Jones, A.L., Miller, A.R., Armitage, A.E., MacRae, N.D.Lamprophyre dikes of the Christopher Island Formation, Thirty Mile Lake, District of Keewatin.Geological Survey of Canada, Paper 1995-C, pp. 187-194.Northwest TerritoriesLamprophyre dykes
DS1995-1140
1995
MacRae, N.D.MacRae, N.D., Armitage, A.E., Jones, A.L.A Diamondiferous lamprophyre dike, Gibson Lake area, NorthwestTerritories.International Geology Review, Vol. 37, pp. 212-229.Northwest TerritoriesLamprophyre, diamond, Deposit -Akluilak dike
DS1996-0870
1996
MacRae, N.D.MacRae, N.D., Armitage, A.E., Miller, A.R., Roddick, J.C.The Diamondiferous Akluilak lamprophyre dyke, Gibson Lake area, northwest TerritoriesGeological Survey of Canada, LeCheminant ed, OF 3228, pp. 101-107.Northwest TerritoriesLamprophyre, Akluilak dyke
DS200912-0841
2009
Macris, C.A.Young, E.D., Tonui, E., Manning, C.E., Schauble, E., Macris, C.A.Spinel olivine magnesium isotope thermometry in the mantle and implications for the MG isotopic composition of Earth.Earth and Planetary Science Letters, Vol. 288, 3-4, pp. 524-533.MantleGeothermometry
DS201012-0881
2009
Macris, C.A.Young, E.D., Tonui, E., Manning, C.E., Schauble, E., Macris, C.A.Spinel olivine magnesium isotope thermometry in the mantle and implications for the Mg isotopic composition of Earth.Earth and Planetary Science Letters, Vol. 288, pp. 524-533..MantleGeochemistry
DS200712-1113
2006
Macthans, H.Vecsei, P., Macthans, H., Schryer, R.Monitoring a sub-arctic lake trout population to determine potential TDS effects from a diamond mining operation at Snap Lake.34th Yellowknife Geoscience Forum, p. 59-60. abstractCanada, Northwest TerritoriesWater
DS2001-0222
2001
MacyealCutler, P.M., Mickelson, Colgan, Macyeal, ParizekInfluence of the Great Lakes on the dynamics of the southern Laurentide ice sheet: numerical experiments.Geology, Vol. 29, No. 11, Nov. pp. 1039-42.Ontario, Michigan, WisconsinGeomorphology, Glacial flow
DS1989-1211
1989
Maczuga, D.E.Phinney, W.C., Morrison, D.A., Maczuga, D.E.Anorthosites and related megacrystic units in the evolution of ArcheancrustJournal of Petrology, Vol. 29, No. 6, pp. 1283-1323. Database # 17977Ontario, Greenland, South AfricaAnorthosites -chromite, Archean
DS201909-2078
2019
Madabhooshi, S.Pothuri, R.C.P., Madabhooshi, S.Petrogenesis of a newly discovered diamondiferous chloritised kimberlite at Dibbasanipalli, Wajrakarur field, southerm India.Goldschmidt2019, 1p. Poster abstractIndiadeposit - Dibbasanipalli

Abstract: Petrogenesis of a newly discovered diamondiferous kimberlite pipe (3-021) by the Rio Tinto Group, ~2 km east of Dibbasanipalli, Wajrakarur Kimberlite Field, eastern Dharwar craton is attempted. The pipe is located in field based on published literature and consultation with local villagers [1,2]. Local geology is dominated by Archaean basement granitoids and genisses intruded by younger nordmarkites and dolerites. The rock is highly chloritised giving rise to poor preservation of kimberlitic matrix. However, olivine pseudomorphs are distinctly visible in thin sections. The rock possesses crustal xenoliths of granite, syenite, dolerite etc. with petrographic similarities to Khaderet pipe (3-106). Geochemically, the kimberlite is silica undersaturated (SiO2 39.32-45.67 wt%), MgO rich (26.51- 28.82 wt%) with K2O (1-88-2.1 wt%) higher than Na2O (0.29-0.39 wt%), akin to archetypal Group-I variety. High amounts of MgO and Mg# correspond to enrichment of magnesium bearing mineral phases like olivine and to some extent Mg-ilmenite. The higher concentration of elements Ba, Cr, Co, Nb, Ni, V, Zr is attributed to enrichment of mantle originated xenocrysts like chromite, perovskite, pyrope, Crdiopside. Based on trace element content, the kimberlite appears to be of magmatic origin within a stable continental geological set up. The enrichment of LREE over HREE supports inferior degree of partial melting (0.1-2%) indicating a metasomatically enriched phlogopite bearing garnet lherzolite source, inturn indicating a deep seated and depleted mantle origin, within an estimated temperature range of 1150- 1280oC and low viscosity (0.05 Pa s).
DS202007-1120
2020
Madani, A.A.Abe, N., Surour, A.A., Madani, A.A., Arai, S.Metasomatized peridotite xenoliths from the Cretaceous rift related Natash volcanics and their bearing on the nature of the lithospheric mantle beneath the southern part of the eastern desert of Egypt.Lithos, in press available , 47p. PdfAfrica, Asia, Egyptperidotites

Abstract: Highly carbonated mantle xenoliths have been found in rift-related alkaline basalts at the Wadi Natash area in the southern part of the Eastern Desert of Egypt. Although all olivine and most orthopyroxene was replaced by carbonate and/or quartz, textural and mineral chemical features show that they are plagioclase-free spinel peridotites (lherzolite to harzburgite). Cr and Mg numbers (Cr#, Mg#) of Cr-spinel vary from 0.06 to 0.45 and 0.73 to 0.81, respectively. The correlation between Cr# and Mg# of the Cr-spinel in the studied xenoliths is weakly negative and its TiO2 content is slightly higher than in abyssal peridotite that was not affected by melt injection. The chemistry of ortho- and clinopyroxene suggests enstatite and chromian diopside compositions, respectively, with distinct signatures of a sub-continental mantle source. In particular, the Na2O contents (>1.0?wt%) and AlVI/AlIV ratios (1.2-2.6) of chromian diopside suggest such an origin. Two-pyroxene geothermometry indicates a temperature of about 900?°C, which is slightly lower than that of ordinary spinel peridotite xenoliths from other rift zones. It is evident that the studied peridotite xenoliths had experienced mantle processes (e.g. decompression melting, magma upwelling and metasomatism) at higher pressure than abyssal peridotites. The trace-element chemistry of clinopyroxene, e.g. high LREE/HREE ratios {(Ce/Yb)n?=?7}, high LREE contents (>3.6?ppm and up to 30.0?ppm Ce) and high Sr between >85.6?ppm and 466?ppm, indicates metasomatic alteration of the peridotite. Clinopyroxene in one sample has very low Ti/Eu and high LREE/HREE ratios. Clinopyroxene with (Ce/Yb)n higher than 3-4 and Ti/Eu ratio lower than 1500 may have experienced carbonatite or carbonate-rich melt metasomatism prior to their incorporation into the host basalt. The basalt itself is almost devoid of any carbonatization and hence the studied mantle peridotites were carbonatized before the generation of the basaltic magma but following an earlier event of K-metasomatism as indicated by the presence of phlogopite. The studied peridotites from the Wadi Natash area were altered by a carbonate-rich melt during a rifting stage. The results of the present paper indicate that the Natash basalts with their peridotite xenoliths extruded along transversal fractures of the NW-trending Nuqra-Kom Ombo-Kharit continental rift on its western shoulder in the south Eastern Desert of Egypt.
DS200712-0480
2007
Madden, P.A.Jahn, S., Madden, P.A.Modeling Earth materials from crustal to lower mantle conditions: a transferable set of interaction potentials for the CMAS system.Physics of the Earth and Planetary Interiors, Vol. 162, 1-2, pp. 129-139.MantleChemistry
DS200712-0481
2007
Madden, P.A.Jahn, S., Madden, P.A.Modeling Earth materials from crustal to lower mantle conditions: a transferable set of interaction potentials for the CMAS system.Physics of the Earth and Planetary Interiors, Vol. 162, 1-2, pp. 129-139.MantleChemistry
DS1990-0972
1990
Maddox, J.Maddox, J.Tectoclimatology comes of ageNature, Vol. 343, February 8, p. 507GlobalMountain Building, Climate
DS1993-0952
1993
Maddox, J.Maddox, J.Calculating the energy of fullerenesNature, Vol. 363, June 3, p. 305.GlobalFullerenes
DS1995-1141
1995
Maddox, J.Maddox, J.Sustainable development unsustainableNature, Vol. 374, No. 6520, March 23, p. 305GlobalEconomics, Environment
DS2003-0785
2003
Maddren, J.Lee, D.C., Maddren, J., Griffin, B.J.The importance of chromite morphology in diamond exploration8 Ikc Www.venuewest.com/8ikc/program.htm, Session 8, POSTER abstractAustraliaBlank
DS200412-1102
2003
Maddren, J.Lee, D.C., Maddren, J., Griffin, B.J.The importance of chromite morphology in diamond exploration.8 IKC Program, Session 8, POSTER abstractAustraliaDiamond exploration
DS1995-1142
1995
Madeira, J.Madeira, J., et al.Spectral (MIR) determination of kaolinite and gibbsite contents in lateritic soilsC.r. Academy Of Science Paris, Vol. 321, 11a, pp. 119-128GlobalLaterites, Spectroscopy
DS201012-0519
2009
Madeira, J.Mourai, C., Mata, J., Doucelance, R., Madeira, J., Brum da Silviera, A., Silva, L.C., Moreira, M.Quaternary extrusive calciocarbonatite volcanism on Brava Island ( Cape Verde): a nephelinite carbonatite immiscibility product.Journal of African Earth Sciences, Vol. 56, 2-3, pp. 59-74.Europe, Cape Verde IslandsCarbonatite
DS201212-0497
2012
Madeira, J.Mourao, C., Mata, J., Doucekance, R., Madeira, J., Millet, M-A., Moreira, M.Geochemical temporal evolution of Brava Island magmatism: constraints on the variability of Cape Verde mantle sources and on carbonatite-silicate magma link.Chemical Geology, Vol. 334, pp. 44-61.Europe, Cape Verde IslandsCarbonatite
DS201212-0498
2012
Madeira, J.Mourao, C., Moreira, M., Mata, J., Raquin, A., Madeira, J.Primary and secondary processes constraining the noble gas isotopic signatures of carbonatites and silicate rocks from Brava Island: evidence for a lower mantle origin of the Cape Verde Plume.Contributions to Mineralogy and Petrology, Vol. 163, 6, pp. 995-1009.Europe, Brava IslandCarbonatite
DS1993-0953
1993
Mader, G.L.Mader, G.L.Permanent satellite tracking networks for geodesy and geodynamicsSpringer-Verlag, 208p. approx. $ 75.00GlobalBook -ad, GPS systems
DS1999-0042
1999
Mader, G.M.Baragar, R.A., Mader, G.M.Carbonatitic ultramafic volcanic rocks (meimechites) of lower most Povungnituk Group, Cape Smith Belt, Quebec.Geological Association of Canada (GAC) Geological Association of Canada (GAC)/Mineralogical Association of Canada (MAC)., Vol. 24, p. 6. abstractQuebec, Labrador, UngavaCarbonatite, Meimechites
DS1996-0871
1996
Mader, H.M.Mader, H.M., et al.Dynamics of explosive degassing of magma: observations of fragmenting two phase flowsJournal of Geophysical Research, Vol. 101, No. B 3, March 10, pp. 5547-60GlobalMagma, Layered intrusion
DS2001-0115
2001
Mader, H.M.Blower, J.D., Mader, H.M., Wilson, S.D.R.Coupling of viscous and diffusive controls on bubble growth during explosive volcanic eruptions.Earth and Planetary Science Letters, Vol. 193, No. 1-2, Nov. 30, pp. 47-56.MantlePhreatomagmatism
DS200612-0848
2006
Mader, H.M.Mader, H.M., Coles, S.G., Connor, C.B., Connor, L.J.Statistics in volcanology. Guide to modern statistical methods applied to volcanology.Geological Society of London, IAVCEI Publication, Oct. 296p.TechnologyBook - volcanology
DS201012-0170
2010
Mader, H.M.Doyle, E.E., Hogg, A.J., Mader, H.M., Sparks, R.S.J.A two layer model for the evolution and propogation of dense and dilute regions of pyroclastic currents.Journal of Volcanology and Geothermal Research, Vol. 190, 3-4, pp. 365-378.TechnologyVolcanism
DS201312-0565
2013
Mader, H.M.Mader, H.M., Llewllin, E.W., Mueller, S.P.The rheology of two phase magmas: a review and analysis.Journal of Volcanology and Geothermal Research, Vol. 257, pp. 135-158.MantleSilicate melt, viscosity ( bubbles or crystals)
DS200612-1401
2006
Mader, M.M.Sylvester, P.J., Mader, M.M., Myers, J.S.Ultramafic alkaline magmas (meymechites) from the mid-Archean Ivistaroq greenstone belt, southwest Greenland.Geochimica et Cosmochimica Acta, Vol. 70, 18, p. 633. abstract only.Europe, GreenlandMeymechites
DS1995-1648
1995
Mader, P.Salomons, W., Forstner, U., Mader, P.Heavy metals... problems and solutionsSpringer, 270p. approx. $ 110.00GlobalBook -ad, Environment -heavy metals
DS1992-0079
1992
Mader, U.Baragar, W.R.A., Mader, U., Le Cheminant, G.M.Lac Leclair carbonatitic ultramafic center, Cape Smith BeltGeological Survey of Canada (GSC) Paper, No. 92-1C, pp. 103-9.Quebec, Ungava, LabradorCarbonatite
DS1992-0080
1992
Mader, U.Baragar, W.R.A., Mader, U., LeCheminant, G.M.Lac Leclair carbonatitic ultramafic volcanic centre, Cape Smith Belt, QuebecGeological Survey of Canada, Paper No. 92-1C, pp. 103-110Quebec, Labrador, UngavaCarbonatite, Lac Leclair
DS2001-0082
2001
Mader, U.Baragar, W.R.A., Mader, U., LeCheminant, G.M.Paleoproterozoic carbonatitic ultrabasic volcanic rocks (meimechites) of Cape Smith Belt, Quebec.Canadian Journal of Earth Sciences, Vol. 38, No. 9, Sept. pp. 1313-34.Quebec, Ungava, LabradorLac Le Clair, Carbonatite, geochemistry, Lapilli tuffs
DS1987-0431
1987
Mader, U.K.Mader, U.K.The Aley carbonatite complex, Northern Rocky Mountain,British SOURCE[ British Columbia Geological Field work 1986British Columbia Geological Fieldwork 1986, Paper No. 1987-1, pp. 283-288British ColumbiaCarbonatite
DS1988-0429
1988
Mader, U.K.Mader, U.K., Greenwood, H.J.Carbonatites and related rocks of the Prince and George Claims Northern Rocky MountainsBritish Columbia Department of Mines, Geological Fieldwork 1987, Paper 1988-1, pp. 375-380British ColumbiaBlank
DS1989-0918
1989
Mader, U.K.Mader, U.K.The Aley carbonatite complex, Northern Rocky Mountains, BritishColumbia(94 B 5)Msc. Thesis University Of British Columbia, British ColumbiaCarbonatite, Aley
DS1986-0514
1986
Mader U.KMader U.KThe Aley carbonatite complexMsc. Thesis University Of British Columbia, 104pBritish ColumbiaCarbonatite
DS1989-0919
1989
Madge, D.N.Madge, D.N.Mine economic valuation and the determination of economic parametersThe Canadian Institute of Mining, Metallurgy and Petroleum (CIM) 91st. Annual Meeting Preprint, No. 81, text 19p. slides 20p. Database # 17969GlobalEconomics, Mine evaluation
DS1990-0973
1990
Madhavan, V.Madhavan, V., Mallikarjuna Rao, J.Petrology of olivine basalt dyke of lamprophyre affinity at Uppalapadu, Prakasam District, Andhra PradeshJournal of Geological Society India, Vol. 36, November pp. 493-501IndiaLamprophyre dike, Petrology
DS1992-0982
1992
Madhavan, V.Madhavan, V., Mallikharjuna Rao, J. Balaram. V., Kumar, R.Geochemistry and petrogenesis of lamprophyres and associated dikes fromElchuru, Andhra Pradesh, IndiaJournal of Geological Society India, Vol. 40, No. 2, August pp. 135-150IndiaLamprophyres, Petrology
DS1992-0983
1992
Madhavan, V.Madhavan, V., Mallikharjuna, J., et al.Geochemistry and petrogenesis of lamprophyres and associated dykes fromElchuru, Andhra Pradesh, India.Journal Geological Society of India, Vol. 40, August pp. 135-149.IndiaLamprophyres, minettes, sannaite, camptonite, Geochemistry
DS1996-1157
1996
Madhavan, V.Rao, C.N.V., Miller, J.A., Pyle, D.M., Madhavan, V.New Proterozoic K-Ar ages for some kimberlites and lamproites from the Cuddapah Basin, Dharwar Craton:Precambrian Research, Vol. 79, pp. 363-369.India, MahbubnagarLamproite, Geochronology, Deposit -Ramannapeta, Kotakonda, Chelima
DS1996-1161
1996
Madhavan, V.Rao, N.V.C., Madhavan, V.Some observations on the geochemistry of Ramannapeta -Ustapalle lamproiticbody, Krishna District AP.Journal of Geological Society India, Vol. 47, No. 4, Apr. 1, pp. 409-418.IndiaLamproite, Deposit -Ramannapeta-Ustapalle
DS1999-0580
1999
Madhavan, V.Rao, N.V.C., Miller, J.A., Madhavan, V.Precise 40 Ar-39 Ar age determinations of the Kotonda kimberlite and Chelima lamproite : implications timingJournal of Geological Society India, Vol. 53, No. 4, Apr. pp. 425-32.IndiaGeochronology - mafic dyke swarm emplacement, Argon, Craton - Dharwar
DS2001-0717
2001
Madhavan, V.Madhavan, V.Rare alkaline rocks from Andhra Pradesh, southern India: an overviewJournal of African Earth Sciences, Vol. 19, No. 3, Apr. pp.321-32.India, Andhra PradeshAlkaline rocks
DS2002-0981
2002
Madhavan, V.Madhavan, V.Comments on : kimberlite occurrence in Raichur area, Karnataka by S. ShivannaJournal of the Geological Society of India, Vol. 60, 5, Oct. pp. 478-80.India, KarnatakaLamproite, lamprophyere
DS200412-1194
2002
Madhavan, V.Madhavan, V.Notes: National seminar on alkaline carbonatite magmatism.Journal Geological Society of India, Vol. 59, 6, pp. 233-234.IndiaConference note
DS200412-1195
2002
Madhavan, V.Madhavan, V.Comments on : kimberlite occurrence in Raichur area, Karnataka by S. Shivanna.Journal of the Geological Society of India, Vol. 60, 5, Oct. pp. 478-80.India, KarnatakaLamproite, lamprophyere
DS200612-0849
2005
Madhavan, V.Madhavan, V.Group II kimberlite or Orangeite? no final verdict in sight.Geological Society of India, Bangalore November Meeting Group Discussion on Kimberlites and Related Rocks India, Abstract p. 114-115.India, Madhya Pradesh, Aravalli Bundelkhand CratonClassification
DS1989-0920
1989
Madhaven, V.Madhaven, V., Mallikharjuna Rao, J., Subrahmanyam, K., KrishnaBedrock geology of the Elchuru alkaline pluton,Prakasam District, AndhraPradeshGeological Society of India, Memoir, Editor C. LeelanandaM., No. 15, pp. 189-206IndiaAlkaline rocks, Lamprophyres
DS1990-0974
1990
Madhaven, V.Madhaven, V., Rao, J.M., Sprininasan, T.P., Sprininansan, M.The mid-Proterozoic dyke swarm of mica lamprophyres and microshonkinites from Elchuru IndiaMafic dykes and emplacement mechanisms, Editors A.J. Parker, P.C., pp. 363-372IndiaLamprophyric dykes, Shonkinites
DS1996-1160
1996
Madhaven, V.Rao, N.V., Chalapthi, Madhaven, V.A new look at the olivine lamproitic rocks of the Maddur Narayanpet area, Mahbubnagar District, A.P.Journal of Geological Society India, Vol. 47, No. 6, June pp. 549-664.IndiaLamproites, Deposit -Maddur Narayanpet
DS1998-0916
1998
Madhaven, V.Madhaven, V., David, K., Srinivas, M.Comparative study of lamprophyres from the Cuddapah Intrusive province(CIP) Andhra Pradesh, India.Journal of Geological Society India, Vol. 52, No. 6, Dec. pp. 621-42.India, South IndiaLamprophyres, Deposit - Elchuru, Purimetla, PrakasaM.
DS1999-0435
1999
Madhaven, V.Madhaven, V., Rao, J.M., Srinivas, M.Mid Proterozoic intraplate alkaline magmatism in the eastern Dharwar Craton of India: the Cuddapah ProvinceJournal of Geological Society IndiaM., Vol. 53, No. 2, Feb. 1, pp. 143-62.India, CuddapahAlkaline rocks, Magmatism, Craton
DS200412-1196
2004
Madhaven, V.Madhaven, V.Continental alkaline magmatism vis a vis the Indian subcontinent: a documentary profile.Journal of the Geological Society of India, Vol. 63, 3, pp. 271-281.IndiaAlkalic
DS1996-1162
1996
Madhavran, V.Rao, NVC, Madhavran, V.Titanium rich phlogopites from the Zangamajupalle kimberlitic rock, AndhraPradesh, India.Journal of Geological Society India, Vol. 47, No. 3, March pp. 355-363.IndiaPetrography, Deposit -Zangamajupalle
DS201512-1920
2015
MadhuraGokhale, M., Madhura, Somani, R., RakeshFullerenes: chemistry and its applications.Mini-Reviews in Organic Chemistry, Vol. 12, 4, pp. 355-366.TechnologyFullerenes

Abstract: Fullerenes being allotropes of carbon, have been considered as new class of molecules. Unlike diamond and graphite, this is made up of hollow carbon cage structure. The idea of spheroidal cage structures of C60 arose from construction of geodesic domes made by renowned architect Buckminster Fuller. Although fullerenes have low solubility in physiological media they finds promising biological applications. The photo, electrochemical and physical properties of C60 and other fullerene derivatives finds applications in medical fields. The ability of fullerenes to fit inside the hydrophobic cavity of HIV proteases makes them potential inhibitor for substrates to catalytic active site of enzyme. It possesses radical scavenging and antioxidant property. At the same time, when it exposed to light it can form singlet oxygen in high quantum yields which with direct electron transfer from excited state of fullerenes and DNA bases finally results in cleavage of DNA. The fullerenes are also used as a carrier for gene and drug delivery system. The associated low toxicity of fullerenes is sufficient to attract the researchers for investigation of these interesting molecules.
DS200512-0673
2005
Madi, K.Madi, K., Forest, S., Cordier, P., Boussuge, M.Numerical study of creep in two phase aggregates with a large rheology contrast: implications for the lower mantle.Earth and Planetary Science Letters, Vol. 237, 1-2, Aug, 30, pp. 223-238.MantleSeismic anistropy
DS1994-1084
1994
MadibaMadiba, CCP, et al.From stoichiometry to nitrogen in ilmenitesHyper. Inter., #QB951, Vol. 91, No. 1-4, pp. 715-719.GlobalIlmenite, Mineralogy
DS1975-1215
1979
Madiba, C.C.P.Sellschop, J.P.F., Madiba, C.C.P., Annegarn, H.J.Volatile Light Elements in DiamondDiamond Research, VOLUME FOR 1979, PP. 24-30.GlobalDiamond Genesis, Microprobe
DS1988-0430
1988
Madiba, C.C.P.Madiba, C.C.P., Sellschop, J.P.F., Van Wyx, J.A.Light volatiles in synthetic diamond analyzed by ion probesNucl. Instrum. Methods Phys. Res. Sect. B., Vol. B35, No. 3-4, 12(II) pp. 442-445GlobalDiamond synthesis
DS1983-0428
1983
Madigan, R.Madigan, R.Diamond Exploration in AustraliaIndiaqua., 1983/II, No. 35, PP. 27-38.AustraliaHistory, Prospecting, Current Actvities, Recovery, Sampling
DS1994-1085
1994
Madill, H.Madson, E., Madill, H., Walker, R.Exploration to development: DIAND's regulatory requirements. #2The Canadian Institute of Mining, Metallurgy and Petroleum (CIM), pp. 25-38.Northwest TerritoriesLegal, environment, Regulations
DS1994-1086
1994
Madill, H.Madson, E., Madill, H., Walker, R.Exploration to development: DIAND's regulatory requirements. #1The Canadian Institute of Mining, Metallurgy and Petroleum (CIM), pp. 25-38.Northwest TerritoriesLegal, Environmental
DS200812-0698
2008
Madison DialogueMadison DialogueDiamonds are forever, and so is sustainable development. Third white paper Making Diamonds Work for Development.madisondialogue.org, July 16, 30p.GlobalNews item - overview
DS1995-0013
1995
Madon, M.Ahmed Zid, I., Madon, M.Electron microscopy of high pressure phases synthesized from natural garnets in a diamond anvil cell: mantle.Earth and Planetary Science Letters, Vol. 129, No. 1-4, January pp. 233-248.MantleGarnet mineralogy, Petrology -experimental
DS1995-0845
1995
Madon, M.Ingrin, J., Madon, M.TEM observations of several spinel garnet assemblages - toward the rheologyof the transition zone.Terra Nova, Vol. 7, No. 5, pp. 509-515.MantlePetrology
DS2003-0091
2003
Madorc, L.Bedard, J.H., Brouillette, P., Madorc, L., Berclaz, A.Archean cratonization and deformation in the northern Superior Province, Canada: anPrecambrian Research, Vol. 127, 1-2, Nov. pp. 61-87.Northwest Territories, QuebecTectonics
DS200412-0121
2003
Madorc, L.Bedard, J.H., Brouillette, P., Madorc, L., Berclaz, A.Archean cratonization and deformation in the northern Superior Province, Canada: an evaluation of plate tectonic versus verticalPrecambrian Research, Vol. 127, 1-2, Nov. pp. 61-87.Canada, Northwest Territories, QuebecTectonics
DS200512-0674
2005
Madore, C.Madore, C., Annesley, I.R., Portella, P.Geology and thermotectonic evolution of the western margin of the Trans-Hudson Orogen: evidence from the eastern sub-Athabasca basement, Saskatchewan.Canadian Journal of Earth Sciences, Vol. 42, 4, April pp. 573-597.Canada, SaskatchewanGeothermometry
DS1993-0954
1993
Madore, L.Madore, L., Girard, R.Etude petrographique et recommendations de travaux dans le cadre de l'exploracion pour le diamant.. Castignon.La Societe Miniere Ecudor Inc., Ressources KWG Inc., 37p.QuebecExploration - assessment, KWG Resources
DS1995-1716
1995
Madore, L.Sharma, K.N.M., Guguere, E., Cimon, J., Madore, L.Les roches ultramafiques dans le Granville de l'Outaoais... contexte tectonique et potential mineralQuebec Department of Mines, Pro 95-08, 6p.QuebecUltramafics
DS1995-1717
1995
Madore, L.Sharma, K.N.M., Guguere, E., Cimon, J., Madore, L.Les roches ultramafiques dans le Grenville de l'Outaoais... contexte tectonique et potential mineralQuebec Department of Mines, Pro 95-08, 6p.QuebecUltramafics
DS2001-0718
2001
Madore, L.Madore, L., Larbi, Y.Regional structural character of the northeastern Ungava Peninsula: connection between Rae and SuperiorGeological Association of Canada (GAC) Annual Meeting Abstracts, Vol. 26, p.93.abstract.Quebec, Ungava, LabradorTectonics - structure
DS201312-0566
2013
Madowe, A.Madowe, A.The mine planning process for an open pit diamond mining operation - a case study on Letseng diamond mine in Lesotho.South African Institute of Mining and Metallurgy, Vol. 113, July pp. 547-554.Africa, LesothoLetseng - mine plan
DS201605-0865
2016
Madowe, A.Madowe, A.Design and implementation of steeper slope angles on a kimberlite open pit diamond operation - a practical approach.Diamonds Still Sparkling SAIMM 2016 Conference, Mar. 14-17, pp. 215-228.TechnologyMining - applied
DS201709-2024
2016
Madowe, A.Madowe, A.Design and implentation of steeper slope angles on a kimberlite open pit diamond operation - a practical approach.South African Institute of Mining and Metallurgy, Vol. 116, 8, pp. 723-731.Africa, Lesothodeposit - Letseng

Abstract: The steepening of slope angles on an open pit mining operation has a material impact on improving the economics of mining. Steepening of slope angles can also increase the risk of slope failure. Slope failures are inherently costly events, because they can be catastrophic, resulting in multiple fatalities, equipment damage, and temporary or permanent closure of a mine. The steepening of the basalt slope angles at Letseng Diamond Mine followed operational improvements that were introduced through improved blasting practices and geotechnical controls. The steeper slope design resulted in a 6 Mt/a reduction in the peak waste mining compared with the previous mine plan coupled with an increase in the net present value and life of mine. This paper is an outline of the steps that were taken at Letseng to increase slope angles in waste and the resulting improvements to the mine plan.
DS1920-0393
1928
Madras MailMadras MailWajrakarurMadras Mail, MAY 2.India, MadrasHistory, Companies
DS1987-0515
1987
MadsenNickel, E.H., Grey, I.E., MadsenLucasite-(Ce),CeTi2(O, Oh06; a new mineral from WesternAustralia: its description and structureAmerican Mineralogist, Vol. 72, pp. 1006-1010Australia, LucasiteLamproite
DS202201-0025
2021
Madsen, A.C.Madsen, A.C.Diamonds: diamond stories. ( only natural diamonds)Assouline Publishing, isbn 978-1649800114GlobalBook - notice

Abstract: Formed billions of years ago deep below the surface of the earth, natural diamonds have always had an ethereal mysticism about them. Once reserved only for royals, red carpets, and life’s most celebratory moments, diamonds were seen as symbols of wealth and prosperity that only few could access. But with a new century comes a new expression of luxury, as a new crop of young designers and heritage jewelry houses alike including Sabyasachi, Messika, Anita Ko, Boucheron, and Fernando Jorge are celebrating natural diamonds as an everyday indulgence. Today’s tastemakers are incorporating diamonds into their designs in unexpected ways, unafraid to play around with interesting cuts and colorful hues. In telling the story of today’s expression of natural diamonds and their continous impact on the world, this new volume dives into tales of the world’s most captivating stones, from the Hope Diamond to the legend of the Beau Sancy Diamond. Featuring stunning images; tall tales; and interviews with top designers, tastemakers, and enthusiasts alike; Diamonds is the definitive book on the world’s most sought-after jewel.
DS2001-0711
2001
Madsen, E.Macdonald, G., Wytrychowski, S., Baker, Madsen, E.Environmental management and monitoring - Diavik 2001 dike contruction29th. Yellowknife Geoscience Forum, Nov. 21-23, abstract p. 55-6.Northwest TerritoriesLegal - environment, Deposit - Diavik
DS201812-2846
2018
Madsen, E.Madsen, E., Truter, K.The transformation of De Beers Canada.2018 Yellowknife Geoscience Forum , p. 49-50. abstractCanadadeposit - De Beers

Abstract: Over the past two years, De Beers Canada has undergone a transformation. This has included: opening the world's largest newdiamond mine (Gahcho Kué Mine); relocating its operational supportcentre to Calgary from Toronto, andrefocusing the Calgary organizationto ensure it provides support servicesto our remote operations rather thanacting as a “head office”; improving partnerships with localcommunities; preparing to close the highlysuccessful Victor Mine in NorthernOntario; and, looking for opportunities to grow thecompany in Canada. The De Beers Canada of 2018 is a dramatically different company, one that has become a solid contributor to the De Beers Group, is a national leader in safety and has its focus on developing the first diamond mine on Baffin Island. Our presentation will provide an update on the activities of De Beers Canada since 2016 and a look ahead at where our company is going in the future.
DS1987-0516
1987
Madsen, I.C.Nickel, E.H., Grey, I.E., Madsen, I.C.Lucasite (Ce) CeTi2 (O, OH)6 a new mineral from Western Australia: its description and structure.American Miner., Vol. 72, pp. 1006-10.AustraliaMineralogy, Lucasite, Deposit - Argyle mine
DS200712-0666
2006
Madsen, J.K.Madsen, J.K., Thorkelson, D.J., Friedman, R.M., Marshall, D.D.Cenozoic to Recent plate configuration in the Pacific Basin: ridge subduction and slab window magmatism in western North America.Geosphere, Vol. 2, pp. 11-34.United States, CanadaSubduction
DS1994-1085
1994
Madson, E.Madson, E., Madill, H., Walker, R.Exploration to development: DIAND's regulatory requirements. #2The Canadian Institute of Mining, Metallurgy and Petroleum (CIM), pp. 25-38.Northwest TerritoriesLegal, environment, Regulations
DS1994-1086
1994
Madson, E.Madson, E., Madill, H., Walker, R.Exploration to development: DIAND's regulatory requirements. #1The Canadian Institute of Mining, Metallurgy and Petroleum (CIM), pp. 25-38.Northwest TerritoriesLegal, Environmental
DS201412-0541
2014
Madugalla, T.B.N.S.Madugalla, T.B.N.S., Pitawala, H.M.T.G.A., Karunaratne, D.G.G.P.Use of carbonatites in the production of precipitated calcium carbonate: a case study from Eppawala, Sri Lanka.Natural Resources Research, Vol. 23, 2, June pp. 217-230.Asia, Sri LankaCarbonatite
DS1984-0470
1984
Madureira filho de, J.B.Madureira filho de, J.B., Svisero, D.P.Diagrama Quinario Para a Determinacao Da Composicao de Granadas Gemologicas.Anais Do Xxxiii Congress Brasilieiro Geologia., PP. 4, 968-4, 978.BrazilNatural, Garnets, Geochemistry, Chemical Analyses
DS1996-0100
1996
MaduskiBeard, A.D., Downes, H., Vetrin, V., Kempton, P.D., MaduskiPetrogenesis of Devonian lamprophyre and carbonatite minor intrusions Kandalaksha Gulf, Kola Peninsula.Lithos, Vol. 39, pp. 93-119.Russia, Kola PeninsulaCarbonatite
DS201705-0808
2017
Madvedev, N.Ashchepkov, I., Ntaflos, T., Logvinova, A., Vladykin, N., Ivanov, A., Spetsius, Z., Stegnitsky, Y., Kostrovitsky, S., Salikhov, R., Makovchuk, I., Shmarov, G., Karpenko, M., Downes, H., Madvedev, N.Evolution of the mantle sections beneath the kimberlite pipes example of Yakutia.European Geosciences Union General Assembly 2017, Vienna April 23-28, 1p. 6337 AbstractRussia, YakutiaDeposit - Sytykanskaya, Dalnyaya, Aykhal, Zarya, Komosomolskaya, Zarnitsa, Udachnaya

Abstract: The PTX diagrams for the separate phases in Sytykanskaya (Ashchepkov et al., 2016) Dalnyaya (Ashchepkov et al., 2017), pipes shows that the PK show the relatively simple P-X trends and geotherms and shows more contrast and simple layering. The PK contain most abundant material from the root of the magma generation they are dunitic veins as the magma feeders represented by the megacrysts. New results for the Aykhal, Zarya and Komsomolskaya pipes in Alake field and Zarnitsa and Udachnaya pipes in Daldyn field show that evolution is accompanied by the developing of metasomatites and branching and veining of the wall rock peridotites . In Aykhal pipe in PK the Gar- dunites prevail, the xenoliths from the dark ABK "Rebus" contain Cr-Ti - rich garnets and ilmenites, more abundant compared with the grey carbonited breccia Nearly the same features were found for Yubileinaya pipe. The example of Komsomolskya pipes show that the ABK contain more eclogitic xenolith than PK. The developing of the magma channel shown in satellite Chukukskaya and Structurnaya pipe was followed by the separation of some parts of the magmatic feeders and crystallization of abundant Gar megacrysts near o the walls blocking the peridotites from the magma feeder. This drastically decrease diamond grade of pipes. Such blocking seems to be the common features for the latest breccias. In Zarnitsa pipe, the dark PK and ABK also contain fresh xenoliths but not only dunites but also sheared and metasomatic varieties and eclogites. Most of dark ABK in Yakutia contain the intergrowth of ilmenites with brown Ti- Cpx showing joint evolution trends. The late breccia contains completely altered peridotite xenoliths mainly of dunite- harzburgite type. The comparison of the trace elements of the coexisting minerals in megacryst show that they were derived from the protokimberlites but are not in complete equilibrium as well as other megacrystalline phases. Ilmenites show inflections of the trace element patterns of most Ilmenites but more regular for the Cpx and Garnets revealing the sub parallel patterns elevating LREE with the rising TRE. But commonly these are not continuous sequances because they developed in the pulsing moving systems like beneath Zarnitsa. The minerals from the feeders like dunites also show the inflected or S-type REE patterns. From the earlier to later phases the TRE compositions became more evolved reflecting the evolution of protokimberlites. The wall rocks also often show the interaction with the more evolved melts and sometimes "cut" spectrums due to the dissolution some phases and repeated melting events So we could suggest the joint evolution of the mantle column protokimberlites and megacrysts composition and type of kimberlites with the diamond grade. The mantle lithospheric base captured by the PK. The developing and rising protokimbelrites was followed by the crystallization of the diamonds in the gradient in FO2 zone in wall rocks due to reductions of C -bearing fluids and carbonatites (> 1 QMF) on peridotites ((< -2 -5 QMF). The most intensive reactions are near the graphite - diamond boundary where protokimberlites are breaking and where most framesites are forming.
DS200612-0253
2006
Madyukov, I.A.Chupin, V.P., Kuzmin, D.V., Madyukov, I.A.Melt inclusions in minerals of scapolite bearing granulite (lower crustal xenoliths from diatremes of the Pamirs).Doklady Earth Sciences, Vol. 407, 3, pp. 507-511.RussiaXenoliths
DS200712-1101
2007
Madyukov, I.A.Urakaev, F.K., Shevchenko, V.S., Logvinoa, A.M., Madyukov, I.A., Petrushin, E.I., Yusupov,T.S.Sobolev.Mechano chemical processing of low grade diamond into nanocomposite materials.Doklady Earth Sciences, Vol. 415, 5, pp. 755-758.RussiaMining - mineral processing
DS201412-0542
2014
Maeda, F.Maeda, F., Ohtani, E., Kamada, S., Sakamaki, T., Ohishi, Y., Hirao, N.The reactions in the MgCO3-SiO2 system in the slabs subducted into the lower mantle and formation of deep diamond.V.S. Sobolev Institute of Geology and Mineralogy Siberian Branch Russian Academy of Sciences International Symposium Advances in high pressure research: breaking scales and horizons ( Courtesy of N. Poikilenko), Held Sept. 22-26, 1p. AbstractSouth America, BrazilCarbon
DS201704-0638
2017
Maeda, F.Maeda, F., Ohtani, E., Kamada, S., Sakamaki, T., Hirao, N., Ohishi, Y.Diamond formation in the deep lower mantle: a high pressure reaction of MgCO3 and SiO2.Nature Scientific reports, Jan. 13, 7p. PdfMantleDiamond, genesis

Abstract: Diamond is an evidence for carbon existing in the deep Earth. Some diamonds are considered to have originated at various depth ranges from the mantle transition zone to the lower mantle. These diamonds are expected to carry significant information about the deep Earth. Here, we determined the phase relations in the MgCO3-SiO2 system up to 152?GPa and 3,100?K using a double sided laser-heated diamond anvil cell combined with in situ synchrotron X-ray diffraction. MgCO3 transforms from magnesite to the high-pressure polymorph of MgCO3, phase II, above 80?GPa. A reaction between MgCO3 phase II and SiO2 (CaCl2-type SiO2 or seifertite) to form diamond and MgSiO3 (bridgmanite or post-perovsktite) was identified in the deep lower mantle conditions. These observations suggested that the reaction of the MgCO3 phase II with SiO2 causes formation of super-deep diamond in cold slabs descending into the deep lower mantle.
DS201911-2534
2019
Maeda, F.Ishi, T., Huang, R., Myhill, R., Fei, H., Koemets, I., Liu, Z., Maeda, F., Yuan, L., Wang, L., Druzhbin, D., Yamamoto, T., Bhat, S., Farla, R., Kawazoe, T., Tsujino, N., Kulik, E., Higo, Y., Tange, H., Katsura, T.Sharp 660 km discontinuity controlled by extremely narrow binary post-spinel transition.Nature Geosciences, Vol. 12, pp. 869-872.Mantlediscontinuity

Abstract: The Earth’s mantle is characterized by a sharp seismic discontinuity at a depth of 660?km that can provide insights into deep mantle processes. The discontinuity occurs over only 2?km—or a pressure difference of 0.1?GPa—and is thought to result from the post-spinel transition, that is, the decomposition of the mineral ringwoodite to bridgmanite plus ferropericlase. Existing high-pressure, high-temperature experiments have lacked the pressure control required to test whether such sharpness is the result of isochemical phase relations or chemically distinct upper and lower mantle domains. Here, we obtain the isothermal pressure interval of the Mg-Fe binary post-spinel transition by applying advanced multi-anvil techniques with in situ X-ray diffraction with the help of Mg-Fe partition experiments. It is demonstrated that the interval at mantle compositions and temperatures is only 0.01?GPa, corresponding to 250?m. This interval is indistinguishable from zero at seismic frequencies. These results can explain the discontinuity sharpness and provide new support for whole-mantle convection in a chemically homogeneous mantle. The present work suggests that distribution of adiabatic vertical flows between the upper and lower mantles can be mapped on the basis of discontinuity sharpness.
DS2001-0849
2001
Maeda, M.Ohtani, E., Maeda, M.Density of basaltic melt at high pressure and stability of the melt at the base of the lower mantle.Earth and Planetary Science Letters, Vol. 193, No. 1-2, pp. 69-75.MantleMorb, picrites, floating diamond method, peridotites, D Layer, discontinuity
DS1996-1033
1996
MaehrNewsom, H.E., Sims, Noll, Jaeger, Maehr, BesserraThe depletion of tungsten in the bulk silicate earth: constraints on coreformation.Geochimica et Cosmochimica Acta, Vol. 60, No. 7, pp. 1155-69.MantleGeochemistry - bulk silicate EARTH backscatter electron (BSE) imaging ., Core formation
DS1997-1034
1997
Maekawa, H.Shibakusa, H., Maekawa, H.Lawsonite bearing eclogitic metabasites in the Cazadero area, northernCalifornia.Mineralogical Magazine, Vol. 61, No. 1-4, pp. 163-180.CaliforniaEclogite
DS1960-0861
1967
Maertens, K.Maertens, K.Edelsteine. #2Hannover: Schmidt-kuster Gmbh, 211P.GlobalKimberlite
DS200412-1197
2004
Maes, J.Maes, J., Iakoubovskii, K., Hayne, M., Stesmans, A., Moshchalkov, V.V.Diamond as a magnetic field calibration probe.Journal of Physics D: Applied Physics, Vol. 37, 7, April 7, pp. 1102-1106.TechnologyGeophysics - magnetics
DS201904-0791
2019
Maes, W.Vanpoucke, D.E.P., Nicely, S.S., Raymakers, J., Maes, W., Haenen, K.Can europium atoms form luminescent centres in diamond: a combined theoretical-experimental study.Diamond and Related Materials, https://doi.org/j. diamond.2019.02.024Globaldiamond morphology

Abstract: The incorporation of Eu into the diamond lattice is investigated in a combined theoretical-experimental study. The large size of the Eu ion induces a strain on the host lattice, which is minimal for the Eu-vacancy complex. The oxidation state of Eu is calculated to be 3+ for all defect models considered. In contrast, the total charge of the defect-complexes is shown to be negative: ?1.5 to ?2.3 electron. Hybrid-functional electronic-band-structures show the luminescence of the Eu defect to be strongly dependent on the local defect geometry. The 4-coordinated Eu substitutional dopant is the most promising candidate to present the typical Eu3+ luminescence, while the 6-coordinated Eu-vacancy complex is expected not to present any luminescent behaviour. Preliminary experimental results on the treatment of diamond films with Eu-containing precursor indicate the possible incorporation of Eu into diamond films treated by drop-casting. Changes in the PL spectrum, with the main luminescent peak shifting from approximately 614?nm to 611?nm after the growth plasma exposure, and the appearance of a shoulder peak at 625?nm indicate the potential incorporation. Drop-casting treatment with an electronegative polymer material was shown not to be necessary to observe the Eu signature following the plasma exposure, and increased the background luminescence.
DS201905-1083
2019
Maes, W.Vanpoucke, D.E.P., Nicley, S.S., Raymakers, J., Maes, W., Haenen, K.Can europium atoms form luminescent centres in diamond: a combined theoretical-experimental study.Diamond & Related Materials, Vol. 94, pp. 233-241.Globalluminescence

Abstract: The incorporation of Eu into the diamond lattice is investigated in a combined theoretical-experimental study. The large size of the Eu ion induces a strain on the host lattice, which is minimal for the Eu-vacancy complex. The oxidation state of Eu is calculated to be 3+ for all defect models considered. In contrast, the total charge of the defect-complexes is shown to be negative: ?1.5 to ?2.3 electron. Hybrid-functional electronic-band-structures show the luminescence of the Eu defect to be strongly dependent on the local defect geometry. The 4-coordinated Eu substitutional dopant is the most promising candidate to present the typical Eu3+ luminescence, while the 6-coordinated Eu-vacancy complex is expected not to present any luminescent behaviour. Preliminary experimental results on the treatment of diamond films with Eu-containing precursor indicate the possible incorporation of Eu into diamond films treated by drop-casting. Changes in the PL spectrum, with the main luminescent peak shifting from approximately 614?nm to 611?nm after the growth plasma exposure, and the appearance of a shoulder peak at 625?nm indicate the potential incorporation. Drop-casting treatment with an electronegative polymer material was shown not to be necessary to observe the Eu signature following the plasma exposure, and increased the background luminescence.
DS1991-1035
1991
Mafarachisi, B.A.Mafarachisi, B.A.Mining is businessRaw Materials Report, Vol. 8, No. 2, pp. 21-22ZimbabweEconomics, Mining
DS1860-0154
1871
Maffei, D.E.Maffei, D.E., Figueroa, D.R.R.Apuntes Para Una Bibliotech Espanola de Libros, Folletos Y AMadrid: J.m. Lapuenta., 529P.GlobalHistory
DS201910-2306
2019
Maffione, M.Van Hinsbergen, D.J.J., Torsvik, T.H., Schmid, S.M., Matenco, L.C., Maffione, M., Vissers, R.L.M., Gurer, D., Spakman, W.Orogenic architecture of the Mediterranean region and kinematic reconstruction of its tectonic evolution since the Triassic. AtriaGondwana Research, in press available 427p.Europecraton

Abstract: The basins and orogens of the Mediterranean region ultimately result from the opening of oceans during the early break-up of Pangea since the Triassic, and their subsequent destruction by subduction accommodating convergence between the African and Eurasian Plates since the Jurassic. The region has been the cradle for the development of geodynamic concepts that link crustal evolution to continental break-up, oceanic and continental subduction, and mantle dynamics in general. The development of such concepts requires a first-order understanding of the kinematic evolution of the region for which a multitude of reconstructions have previously been proposed. In this paper, we use advances made in kinematic restoration software in the last decade with a systematic reconstruction protocol for developing a more quantitative restoration of the Mediterranean region for the last 240 million years. This restoration is constructed for the first time with the GPlates plate reconstruction software and uses a systematic reconstruction protocol that limits input data to marine magnetic anomaly reconstructions of ocean basins, structural geological constraints quantifying timing, direction, and magnitude of tectonic motion, and tests and iterations against paleomagnetic data. This approach leads to a reconstruction that is reproducible, and updatable with future constraints. We first review constraints on the opening history of the Atlantic (and Red Sea) oceans and the Bay of Biscay. We then provide a comprehensive overview of the architecture of the Mediterranean orogens, from the Pyrenees and Betic-Rif orogen in the west to the Caucasus in the east and identify structural geological constraints on tectonic motions. We subsequently analyze a newly constructed database of some 2300 published paleomagnetic sites from the Mediterranean region and test the reconstruction against these constraints. We provide the reconstruction in the form of 12 maps being snapshots from 240 to 0 Ma, outline the main features in each time-slice, and identify differences from previous reconstructions, which are discussed in the final section.
DS200712-1084
2006
Magaina, L.O.Titkov, S.V., Solodova, Y.P., Gorshkov, A.I., Magaina, L.O., Sivtsov, A.V., Sedova, E.A., Gasanov, SamosorovInclusions in white gray diamonds of cubic habit from Siberia.Gems & Gemology, 4th International Symposium abstracts, Fall 2006, p.127-8. abstract onlyRussiaDiamond morphology
DS201212-0448
2012
Magaji, S.S.Martin, R.F., Sokolov, M., Magaji, S.S.Punctuated anorogenic magmatism.Lithos, Vol. 152, pp. 132-140.Canada, Greenland, Russia, AfricaMagmatism
DS201709-2025
2017
Magalhaes, N.Magalhaes, N., Magna, T., Rapprich, V., Kratky, O., Farquhar, J.Sulfur isotope systematics in carbonatites from Sevattur and Samalpatti, S India.Goldschmidt Conference, abstract 1p.Indiacarbonatites, Sevattur, Samalpatti

Abstract: We report preliminary data for sulfur isotopes from two spatially related Neoproterozoic carbonatite complexes in Tamil Nadu, S India, with the aim of getting further insights into their magmatic and/or post-emplacement histories [1]. The major sulfide phase in these rocks is pyrite, with minor chalcopyrite, whereas sulfate occurs as barite. A bimodal distribution of G34Ssulfide is found for Samalpatti (13.5 to 14.0‰), and Sevattur (?2.1 to 1.4‰) carbonatites. A significantly larger range of G34Ssulfide values is found for the associated Samalpatti silicate rocks (?5.2 to 7.4‰) relative to Sevattur pyroxenites and gabbros (?1.1 to 2.1‰). High G34Ssulfide values for Samalpatti carbonatites are unsual [2,3] but could reflect hydrothermal post-emplacement modification [1] of S isotopes. The low G34Ssulfide values for Sevattur may represent a mantle source signature. The G34Ssulfate is uniformly positive for both complexes, with most data falling in a narrow range (5.7 to 7.8‰) and one datum for a pyroxenite yielding more positive G34Ssulfate = 13.3‰. Data for '33S varies outside of analytical uncertainty (?0.07 to 0.04‰), indicating contribution from a source with a surface-derrived component. The small range of '33S values does not allow us to determine whether these sources contain S fractionated by biogeochemical (mass-dependent) or photochemical (mass-independent, pre GOE) processes. Data for '36S is positive, and varies within uncertainty (0.28 ± 0.15‰). Variations of this magnitude have been observed in other localities, and are not diagnostic of any unique source or process. The sulfur isotope data imply addition of crustal sulfur to Samalpatti. In contrast, sulfur from Sevattur has a mantle-like G34S but '33S with anomalous character. These observations support the idea of a different evolutionary story for these complexes, possibly more complex than previously thought.
DS202008-1390
2020
Magalhaes, N.Fitzpaynek, A., Giuliani, A., Magalhaes, N., Soltys, A., Fiorentini, M., Farquhar, J.The petrology and sulphur istopic composition of sulphide and sulphate in the Kimberley kimberlites.Goldschmidt 2020, 1p. AbstractAfrica, South Africadeposit - Kimberley

Abstract: The petrology and bulk-rock sulphur isotopic compositions of kimberlite samples from four localities (Bultfontein, De Beers, Kimberley, Wesselton) of the archetypal Kimberley cluster, South Africa, were used to investigate the origin(s) of S in kimberlites and gain insights into the occurrence of recycled crustal material in the source of Mesozoic kimberlites. The samples, which show variable degrees of alteration, are all hypabyssal and were derived from coherent root-zones as well as dykes and sills. Typical sulphide minerals are Cu-Fe-Ni-sulphides with less common pyrite, galena, sphalerite, and djerfisherite. They occur in a variety of textural associations, for example as groundmass phases, secondary inclusions in olivine, inclusions in matrix phases (e.g., phlogopite), or in carbonate-serpentine segregations. Barite is the most commonly observed sulphate phase. Bulk-sample ?34SVCDT values of sulphides in fresh kimberlites, which mostly do not contain barite, vary from - 2.0 to -5.7 ‰. Slightly altered kimberlite samples, in which sulphides were generally associated with serpentine, returned somewhat higher bulk-sulphide ?34SVCDT (-3.8 to +1.1 ‰). One sample from the Wesselton Water Tunnel Sills complex contains abundant barite and pyrite in its groundmass, with the latter having ?34SVCDT (+0.2 to +1.9 ‰) similar to altered kimberlites. Two further altered samples returned ?34SVCDT values (-10.1 to -13.0 ‰) that suggest a contribution from the local country rocks (Dwyka shale: ?34SVCDT from -10.2 to -10.5 ‰). All samples have near-zero ?33S values, suggesting that material displaying mass-independent fractionation has not played an important role. The negative ?34SVCDT values of fresh kimberlites from Kimberley suggest the involvement of recycled crustal material in their source, which is consistent with radiogenic isotope compositions. Overall, it appears that most kimberlitic sulphide S isotopic compositions can be explained by the action of a few typical magmatic/hydrothermal processes.
DS201812-2847
2018
Magalhaes Macedo, J.Magalhaes Macedo, J.Gar Mineracao - discoveries, geology and development of diamond deposits of Romaria and Monte Carmelo.7th Symposio Brasileiro de Geologia do Diamante , Title only South America, Brazildeposit - Romaria, Monte Carmelo
DS201412-0013
2014
Magana, S.Ardon, T., Magana, S.Spatial correlation of infrared and PL optical centers in hydrogen rich diamonds.Geological Society of America Conference Vancouver Oct. 19-22, 1p. AbstractAfrica, ZimbabweDiamond absorption
DS201604-0636
2016
Magana, Z.Thomas, R.J, Spencer, C., Bushi, A.M., Baglow, N., Gerrit de Kock, B., Hortswood, M.S.A., Hollick, L., Jacobs, J., Kajara, S., Kaminhanda, G., Key, R.M., Magana, Z., McCourt, M.W., Momburi, P., Moses, F., Mruma, A., Myamilwa, Y., Roberts, N.M.W., HamisiGeochronology of the centra Tanzania craton and its southern and eastern orogenic margins.Precambrian Research, in press available 57p.Africa, TanzaniaGeochronology

Abstract: Geological mapping and zircon U-Pb/Hf isotope data from 35 samples from the central Tanzania Craton and surrounding orogenic belts to the south and east allow a revised model of Precambrian crustal evolution of this part of East Africa. The geochronology of two studied segments of the craton shows them to be essentially the same, suggesting that they form a contiguous crustal section dominated by granitoid plutons. The oldest orthogneisses are dated at ca. 2820 Ma (Dodoma Suite) and the youngest alkaline syenite plutons at ca. 2610 Ma (Singida Suite). Plutonism was interrupted by a period of deposition of volcano-sedimentary rocks metamorphosed to greenschist facies, directly dated by a pyroclastic metavolcanic rock which gave an age of ca. 2725 Ma. This is supported by detrital zircons from psammitic metasedimentary rocks, which indicate a maximum depositional age of ca. 2740 Ma, with additional detrital sources 2820 and 2940 Ma. Thus, 200 Ma of episodic magmatism in this part of the Tanzania Craton was punctuated by a period of uplift, exhumation, erosion and clastic sedimentation/volcanism, followed by burial and renewed granitic to syenitic magmatism. In eastern Tanzania (Handeni block), in the heart of the East African Orogen, all the dated orthogneisses and charnockites (apart from those of the overthrust Neoproterozoic granulite nappes), have Neoarchaean protolith ages within a narrow range between 2710 and 2630 Ma, identical to (but more restricted than) the ages of the Singida Suite. They show evidence of Ediacaran "Pan-African" isotopic disturbance, but this is poorly defined. In contrast, granulite samples from the Wami Complex nappe were dated at ca. 605 and ca. 675 Ma, coeval with previous dates of the "Eastern Granulites" of eastern Tanzania and granulite nappes of adjacent NE Mozambique. To the south of the Tanzania Craton, samples of orthogneiss from the northern part of the Lupa area were dated at ca. 2730 Ma and clearly belong to the Tanzania Craton. However, granitoid samples from the southern part of the Lupa "block" have Palaeoproterozoic (Ubendian) intrusive ages of ca. 1920 Ma. Outcrops further south, at the northern tip of Lake Malawi, mark the SE continuation of the Ubendian belt, albeit with slightly younger ages of igneous rocks (ca. 1870-1900 Ma) which provide a link with the Ponte Messuli Complex, along strike to the SE in northern Mozambique. In SW Tanzania, rocks from the Mgazini area gave Ubendian protolith ages of ca. 1980-1800 Ma, but these rocks underwent Late Mesoproterozoic high-grade metamorphism between 1015 and 1040 Ma. One granitoid gave a crystallisation age of ca. 1080 Ma correlating with known Mesoproterozoic crust to the east in SE Tanzania and NE Mozambique. However, while the crust in the Mgazini area was clearly one of original Ubendian age, reworked and intruded by granitoids at ca. 1 Ga, the crust of SE Tanzania is a mixed Mesoproterozoic terrane and a continuation from NE Mozambique. Hence the Mgazini area lies at the edge of the Ubendian belt which was re-worked during the Mesoproterozoic orogen (South Irumide belt), providing a further constraint on the distribution of ca. 1 Ga crust in SE Africa. Hf data from near-concordant analyses of detrital zircons from a sample from the Tanzania Craton lie along a Pb-loss trajectory (Lu/Hf = 0), extending back to ?3.9 Ga. This probably represents the initial depleted mantle extraction event of the cratonic core. Furthermore, the Hf data from all igneous samples, regardless of age, from the entire study area (including the Neoproterozoic granulite nappes) show a shallow evolution trend (Lu/Hf = 0.028) extending back to the same mantle extraction age. This implies the entire Tanzanian crust sampled in this study represents over 3.5 billion years of crustal reworking from a single crustal reservoir and that the innermost core of the Tanzanian Craton that was subsequently reworked was composed of a very depleted, mafic source with a very high Lu/Hf ratio. Our study helps to define the architecture of the Tanzanian Craton and its evolution from a single age-source in the early Eoarchaean.
DS1997-0714
1997
Magang, D.N.Magang, D.N.Presentation by the Minister of Mineral resources and Water Affairs of the Republic of BotswanaMiga Conference Held Denver June 3-5, 10pBotswanaMining
DS1997-0715
1997
Magang, D.N.Magang, D.N., Tomable, A.R., Ntsimanyana, M.Mining potential of BotswanaMiga Conference Held Denver June 3-5, 37pBotswanaMining, Overview
DS1997-0716
1997
Magang, D.N.Magang, D.N., Tomable, A.R., Ntsimanyana, M.Mining potential of BotswanaMiga Conference Held Denver June 3-5, 37p.BotswanaMining, Overview
DS201610-1840
2016
Magaraggia, R.Aravanis, T., Chen, J., Fuechsle, M., Grujic, M., Johnston, P., Kok, Y., Magaraggia, R., Mann, A., Mann, L., McIntoshm S., Rheinberger, G., Saxey, D., Smalley, M., van Kann, F., Walker, G., Winterflood, J.VK1 tm - a next generation airborne gravity gradiometer.ASEG-PESA-AIG 2016 25th Geophysical Conference, Abstract 5p.TechnologyGradiometer

Abstract: The minerals exploration industry’s demand for a highly precise airborne gravity gradiometer has driven development of the VK1TM Airborne Gravity Gradiometer, a collaborative effort by Rio Tinto and the University of Western Australia. VK1TM aims to provide gravity gradient data with lower uncertainty and higher spatial resolution than current commercial systems. In the recent years of VK1TM development, there have been significant improvements in hardware, signal processing and data processing which have combined to result in a complete AGG system that is approaching competitive survey-ready status. This paper focuses on recent improvements. Milestone-achieving data from recent lab-based and moving-platform trials will be presented and discussed, along with details of some advanced data processing techniques that are required to make the most use of the data.
DS1991-1036
1991
Magaritz, M.Magaritz, M.Carbon isotopes, time boundaries and evolutionTerra Nova, Vol. 3, No. 3, pp. 251-256GlobalCarbonates, Geochronology
DS2000-0355
2000
MagazinaGorshkov, A. Bao, Titkov, Ryabchikov, Magazina, SivtsovComposition of mineral inclusions and formation of polycrystalline diamond aggregates ( Bort) Shengli pipeGeochemistry International, Vol. 38, No. 7, pp. 698-705.ChinaMineralogy - bort, Deposit - Shengli, Shenli
DS200612-1429
2006
MagazinaTitkov, S.V., Gorshkov, A.I., Solodova, Ryabchikov, Magazina, Sivtsov, Gasanov, Sedova, SamosorovMineral Micro inclusions in cubic diamonds from the Yakutian deposits based on analytical electron microscopy data.Doklady Earth Sciences, Vol. 410, no. 7 July-August, pp. 1106-1108.Russia, YakutiaDiamond inclusions
DS1995-1364
1995
Magazina, L.O.Novgorodova, M.I., Samotoin, N.D., Magazina, L.O.Packing defect regularity in graphite from deep seated xenolithsDoklady Academy of Sciences, Vol. 334, No. 1, Aug., pp. 97-101.ChinaXenoliths, Deposit Tuvish pipe
DS1999-0260
1999
Magazina, L.O.Gorshkov, A.I., Bao, Y.N., Magazina, L.O.Polycrystalline diamond aggregate (bort) from Shanley kimberlite pipe, China: growth features, genesisGeochemistry International, Vol. 37, No. 1, Jan. pp. 75-81.ChinaDiamond morphology - bort, Deposit - Shanley
DS2003-1381
2003
Magazina, L.O.Tikov, S.V., Zudin, N.G., Gorshkov, A.I., Sivtsov, A.V., Magazina, L.O.An investigation into the cause of colour in natural black diamonds from SiberiaGems & Gemology, Vol. 39,3, Fall, pp. 200-209.Russia, SiberiaMineral inclusions - Mir
DS200412-1995
2003
Magazina, L.O.Tikov, S.V., Zudin, N.G., Gorshkov, A.I., Sivtsov, A.V., Magazina, L.O.An investigation into the cause of colour in natural black diamonds from Siberia.Gems & Gemology, Vol. 39,3, Fall, pp. 200-209.Russia, SiberiaMineral inclusions - Mir
DS200412-2000
2004
Magazina, L.O.Titkov, S.V., Gorshkov, A.I., Magazina, L.O., Sivtsov, A.V., Zakharchenko, O.D.Shapeless dark diamonds ( Yakutites) from placers of the Siberian platform and criteria of their impact origin.Geology of Ore Deposits, Vol. 46, 3, pp. 191-201.Russia, SiberiaDiamond morphology
DS200612-0480
2006
Magazina, L.O.Gorshkov, A.I., Titkov, S.V., Bao, Y.N., Ryabchikov, I.D., Magazina, L.O.Micro inclusions in diamonds of octahedral habit from kimberlites of Shandong province, eastern China.Geology of Ore Deposits, Vol. 48, 4, pp. 326-China, ShandongDiamond morphology, inclusions
DS200612-0481
2006
Magazina, L.O.Gorshkov, A.L., Titkov, S.V., Bao, Y.N., Ryabchikov, I.D., Magazina, L.O.Micro inclusions in diamonds of octahedral habit from kimberlites of Shandong Province, eastern China.Geology of Ore Deposits, Vol. 48, 4, pp 326-334.ChinaDiamond crystallography
DS201112-1049
2011
Magazina, L.O.Titkov, S.V., Ryabchikov, I.D., Pomazanskii, B.S., Magazina, L.O.Chloride Micro inclusions in diamonds of the Siberian Platform.Doklady Earth Sciences, Vol. 437, 2, pp. 503-506.Russia, SiberiaDiamond inclusions
DS201903-0529
2018
Magazina, L.O.Lykhin, D.A., Yarmolyuk, V.V., Nikiforov, A.V., Kozlovsky, A.M., Magazina, L.O.Ulan-Tologoi Ta - Nb deposit: the role of magmatism in the formation of rare metal mineralization.Geology of Ore Deposits, Vol. 60, 6, pp. 461-85.Asia, MongoliaREE

Abstract: The role of magmatic differentiation is considered for the formation of the Ulan-Tologoi Ta-Nb-Zr deposit (northwestern Mongolia) related to the eponymous alkali granite pluton. Data are presented on the structure of the pluton, the composition of its rocks, and distribution of rare metal mineralization. The ores of the pluton include alkali granites with contents of ore elements exceeding the normative threshold for Ta (>100 ppm). The rare metal mineralization includes pyrochlore, columbite, zircon, bastnaesite, monazite, and thorite, which are typical of all alkali-salic rocks; however, their amount varies depending on the REE content of the rocks. The pluton was formed ~298 Ma ago under the influence of a mantle-crustal melt source.
DS200712-0080
2007
Magee, C.Birch, W.D., Barron, L.M., Magee, C., Sutherland, F.L.Gold and diamond bearing White Hills Gravel, St. Arnaud district, Victoria: age and provenance based on U Pb dating of zircon and rutile.Australian Journal of Earth Sciences, Vol. 54, 4, pp. 609-628.Australia, VictoriaGeochronology
DS200812-0113
2007
Magee, C.Birch, W.D., Barron, L.M., Magee, C., Sutherland, F.L.Gold and diamond bearing White Hills gravel, St. Arnaud district, Victoria: age and provenance based on U-Pb dating of zircon and rutile.Australian Journal of Earth Sciences, Vol. 54, 4, June pp. 609-628.Australia, VictoriaGeochronology
DS201509-0415
2015
Magee, C.Magee, C., Mahaaj, S.M., Wrona, T., Jackson, A-L.Controls on the expression of igneous intrusions in seismic reflection data.Geosphere, Vol. 11, 4, pp. 1024-1041.MantleMagmatism

Abstract: The architecture of subsurface magma plumbing systems influences a variety of igneous processes, including the physiochemical evolution of magma and extrusion sites. Seismic reflection data provides a unique opportunity to image and analyze these subvolcanic systems in three dimensions and has arguably revolutionized our understanding of magma emplacement. In particular, the observation of (1) interconnected sills, (2) transgressive sill limbs, and (3) magma flow indicators in seismic data suggest that sill complexes can facilitate significant lateral (tens to hundreds of kilometers) and vertical (<5 km) magma transport. However, it is often difficult to determine the validity of seismic interpretations of igneous features because they are rarely drilled, and our ability to compare seismically imaged features to potential field analogues is hampered by the limited resolution of seismic data. Here we use field observations to constrain a series of novel seismic forward models that examine how different sill morphologies may be expressed in seismic data. By varying the geologic architecture (e.g., host-rock lithology and intrusion thickness) and seismic properties (e.g., frequency), the models demonstrate that seismic amplitude variations and reflection configurations can be used to constrain intrusion geometry. However, our results also highlight that stratigraphic reflections can interfere with reflections generated at the intrusive contacts, and may thus produce seismic artifacts that could be misinterpreted as real features. This study emphasizes the value of seismic data to understanding magmatic systems and demonstrates the role that synthetic seismic forward modeling can play in bridging the gap between seismic data and field observations.
DS201807-1510
2018
Magee, C.Magee, C., Stevenson, C.T.E., Ebmeier, S.K., Keir, D., Hammond, J.O.S., Gottsmann, J.H., Whaler, K.A., Schofield, N., Jackson, C.A-L., Petronis, M.S., O'Driscoll, B., Morgan, J., Cruden, A., Vollgger, S.A., Dering, G., Micklethwaite, S., Jackson, M.D.Magma plumbing systems: a geophysical perspective. InSAR, GPS, GNSS, FWI, UAVsJournal of Petrology, in press available, 99p.Mantlemagmatism - geophysics

Abstract: Over the last few decades, significant advances in using geophysical techniques to image the structure of magma plumbing systems have enabled the identification of zones of melt accumulation, crystal mush development, and magma migration. Combining advanced geophysical observations with petrological and geochemical data has arguably revolutionised our understanding of, and afforded exciting new insights into, the development of entire magma plumbing systems. However, divisions between the scales and physical settings over which these geophysical, petrological, and geochemical methods are applied still remain. To characterise some of these differences and promote the benefits of further integration between these methodologies, we provide a review of geophysical techniques and discuss how they can be utilised to provide a structural context for and place physical limits on the chemical evolution of magma plumbing systems. For example, we examine how Interferometric Synthetic Aperture Radar (InSAR), coupled with Global Positioning System (GPS) and Global Navigation Satellite System (GNSS) data, and seismicity may be used to track magma migration in near real-time. We also discuss how seismic imaging, gravimetry, and electromagnetic data can identify contemporary melt zones, magma reservoirs, and, or, crystal mushes. These techniques complement seismic reflection data and rock magnetic analyses that delimit the structure and emplacement of ancient magma plumbing systems. For each of these techniques, with the addition of full-waveform inversion (FWI), the use of Unmanned Aerial Vehicles (UAVs), and the integration of geophysics with numerical modelling, we discuss potential future directions. We show that approaching problems concerning magma plumbing systems from an integrated petrological, geochemical, and geophysical perspective will undoubtedly yield important scientific advances, providing exciting future opportunities for the volcanological community.
DS1998-0917
1998
Magee, C.W.Magee, C.W., Taylor, W.R.Constraints on the history and origin of carbonado from luminescencestudies.7th International Kimberlite Conference Abstract, pp. 527-8.Brazil, Central African RepublicCarbonado, Cathodluninescence, Photoluminescence
DS1999-0436
1999
Magee, C.W.Magee, C.W., Taylor, W.R.Constraints from luminesence on the history and origin of carbonado7th International Kimberlite Conference Nixon, Vol. 2, pp. 529-32.Central African Republic, BrazilCarbonado
DS2002-0982
2002
Magee, C.W.Magee, C.W., Taylor, W.R.Raman, cathodluminescence and optical observations of carbonado microstructureEos, American Geophysical Union, Spring Abstract Volume, Vol.83,19, 1p.Central African Republic, South America, BrazilDiamond - morphology, carbonado
DS201610-1845
2016
Magee, C.W.Beyer, C., Klemme, S., Grutzner, T., Ireland, T.R., Magee, C.W., Frost, D.J.Fluorine partitioning between eclogitic garnet, clinopyroxene, and melt at upper mantle conditions.Chemical Geology, Vol. 437, pp. 88-97.MantleLamproite

Abstract: In this experimental study we obtained new mineral/melt (DF = cmineral/cmelt) partitioning data for fluorine in a bimineralic hydrous eclogite under Earth's upper mantle conditions (4-6 GPa, 1460-1550 °C). Omphacitic clinopyroxene displays mineral/melt partition coefficients between DF = 0.056 ± 0.005 and DF = 0.074 ± 0.001. Garnet partition coefficients are consistently lower with an average partition coefficient of DF = 0.016 ± 0.003. We found that omphacitic clinopyroxene is the dominant nominally fluorine-free phase in subducted oceanic crust and hence omphacite is expected to be the major fluorine carrier during subduction of crust into the deeper mantle. Together with previously obtained partitioning data we propose that the oceanic crust can host more fluorine per mass unit than the underlying depleted oceanic mantle. If the majority of entrained fluorine is recycled into Earth's transition zone it is possible that the fluorine is either incorporated into high-pressure transition zone phases or released during high-pressure phase transformations and forming fluorine-rich small degree partial melts. Both scenarios are supported by elevated fluorine concentration in ocean island basalts, kimberlites, and lamproites. Combining the fluorine partitioning data with water partitioning data yields a plausible process to generate lamproitic magmas with a high F/H2O ratio. The enrichment of fluorine relative to H2O is triggered by multiple episodes of small degree melting that deplete the residual more in H2O than in fluorine, caused by the approximately three times smaller mineral-melt partition coefficients of H2O.
DS2003-0365
2003
Magee, D.Eccles, D.R., Pana, D.I., Paulen, R.C., Olson, R.A., Magee, D.Discovery and geological setting of the northern Alberta kimberlite provinceIn: 8th. International Kimberlite Conference Slave Province And Northern Alberta, pp. 1-10.AlbertaGeology
DS2003-0367
2003
Magee, D.Eccles, R., Olson, R., Magee, D.Mineral trains, but no gravy train as diamond hunt continuesPdac Exploration And Development Highlights, March, pp. 24-5.AlbertaNews item, Overview
DS2003-0368
2003
Magee, D.Eccles, R., Olson, R.A., Magee, D.Mineral trains, but no gravy train as diamond hunt continuesExploration and Development Highlights, March 2003, p. 24-25Albertaexploration activity
DS200412-0501
2003
Magee, D.Eccles, D.R., Pana, D.I., Paulen, R.C., Olson, R.A., Magee, D.Discovery and geological setting of the northern Alberta kimberlite province.8th. International Kimberlite Conference Slave Province and Northern Alberta Field Trip Guidebook, pp. 1-10.Canada, AlbertaGeology
DS1991-1941
1991
Magee, M.Zoback, M.L., Magee, M.Stress magnitudes in the crust -constraints from stress orientation and relative magnitude dataPhil. Transactions Royal Society of London, Vol. 337, No. 1645, October 15, pp. 181-195GlobalCrust, Tectonics
DS2000-0606
2000
Maggi, A.Maggi, A., Jackson, J.A., McKenszie, D., Priestley, K.Earthquake focal depths, effective elastic thickness and the strength of the continental lithosphere.Geology, Vol. 28, No. 6, June pp. 495-8.MantleEarthquakes - crustal thickness, Seismogenic crust
DS1984-0492
1984
Maggiore, C.Mathez, E.A., Blacic, J.D., Beery, J., Maggiore, C., Hollander.Carbon Abundances in Mantle Minerals Determined by Nuclear Reaction Analysis.Geophysical Research. LETTERS, Vol. 11, No. 10, OCTOBER, PP. 947-950.United States, Colorado Plateau, New MexicoXenolith, Crystallography
DS1986-0533
1986
Maggiore, C.Mathez, E.A., Blacic, J.D., Beery, J., Maggiore, C., Hollander, M.Carbon in olivine by nuclear reaction analysisProceedings of the Fourth International Kimberlite Conference, Held Perth, Australia, No. 16, pp. 273-275GlobalBlank
DS1987-0444
1987
Maggiore, C.Mathez, E.A., Blacic, J.D., Beery, J., Hollander, M., Maggiore, C.Carbon in olivine: results from nuclear reaction analysisJournal of Geophys., Res, Vol. 92, No. B5, April 10, pp. 3500-3506GlobalMantle genesis
DS1991-0125
1991
Maggiore, C.Blacic, J.D., Mathez, E.A., Maggiore, C., Mitchell, T.E., Fogel, R.Oxygen in diamond by the nuclear microprobe: analytical technique and initial resultsProceedings of Fifth International Kimberlite Conference held Araxa June 1991, Servico Geologico do Brasil (CPRM) Special, pp. 20-22GlobalMicroprobe, Oxygen analyses
DS1993-0980
1993
Maggiore, C.Mathez, E.A., Blacic, J.D., Maggiore, C., Mitchell, T.E., Fogel, R.A.The determination of the O content of diamond by microactivationAmerican Mineralogist, Vol. 78, No. 7-8, July-August pp. 753-761.South Africa, Botswana, ZaireKimberlites, Deposit -Monastery, Finsch, Orapa, Muji Mayi
DS2001-0483
2001
MagloughlinHoldsworth, R.E., Strachan, R.A., Magloughlin, KnipeThe nature and tectonic significance of fault zone weakeningGeological Society of London - Book, No. 186, 328p. approx. $120.00 United StatesGlobalBook - ad, Structure, faulting, tectonics
DS2001-0484
2001
MagloughlinHoldsworth, R.E., Strachan, R.A., Magloughlin, KnipeThe nature and tectonic significance of fault zone weakeningGeological Society of London, No. 186, 350p.GlobalBook - table of contents, Tectonics - deformation, fault systems
DS1996-0872
1996
Magloughlin, J.Magloughlin, J., Chester, F.M., Spray, J.Fine grained fault rocks... overview of Penrose conferenceGsa Today, Vol. 6, No. 4, April pp. 33-37GlobalTectonics, Fault rock genesis, mechanisms, deformation
DS200812-0699
2008
Magna, T.Magna, T., Ionov, D.A., Oberli, F., Wiechert, U.Links between mantle metasomatism and lithium isotopes: evidence from glass bearing and cryptically metasomatized xenoliths from Mongolia.Earth and Planetary Science Letters, Vol. 276, 1-2, Nov. pp. 214-222.Asia, MongoliaMetasomatism
DS201504-0183
2015
Magna, T.Barry, P.H., Hilton, D.R., Day, J.M.D., Pernet-Fisher, J.F., Howarth, G.H., Magna, T., Agashev, A.M., Pokhilenko, N.P., Opkhilenko, L.N., Taylor, L.A.Helium isotope evidence for modification of the cratonic lithosphere during the Permo-Triassic Siberian flood basalt event.Lithos, Vol. 216-217, pp. 73-80.Russia, SiberiaDeposit - Udachnaya, Obnazhennaya

Abstract: Major flood basalt emplacement events can dramatically alter the composition of the sub-continental lithospheric mantle (SCLM). The Siberian craton experienced one of the largest flood basalt events preserved in the geologic record — eruption of the Permo-Triassic Siberian flood basalts (SFB) at ~250 Myr in response to upwelling of a deep-rooted mantle plume beneath the Siberian SCLM. Here, we present helium isotope (3 He/ 4 He) and concentra-tion data for petrologically-distinct suites of peridotitic xenoliths recovered from two temporally-separated kim-berlites: the 360 Ma Udachnaya and 160 Ma Obnazhennaya pipes, which erupted through the Siberian SCLM and bracket the eruption of the SFB. Measured 3 He/ 4 He ratios span a range from 0.1 to 9.8 R A (where R A = air 3 He/ 4 He) and fall into two distinct groups: 1) predominantly radiogenic pre-plume Udachnaya samples (mean clinopyroxene 3 He/ 4 He = 0.41 ± 0.30 R A (1?); n = 7 excluding 1 outlier), and 2) 'mantle-like' post plume Obnazhennaya samples (mean clinopyroxene 3 He/ 4 He = 4.20 ± 0.90 R A (1?); n = 5 excluding 1 outlier). Olivine separates from both kimberlite pipes tend to have higher 3 He/ 4 He than clinopyroxenes (or garnet). Helium con-tents in Udachnaya samples ([He] = 0.13–1.35 ?cm 3 STP/g; n = 6) overlap with those of Obnazhennaya ([He] = 0.05–1.58 ?cm 3 STP/g; n = 10), but extend to significantly higher values in some instances ([He] = 49– 349 ?cm 3 STP/g; n = 4). Uranium and thorium contents are also reported for the crushed material from which He was extracted in order to evaluate the potential for He migration from the mineral matrix to fluid inclusions. The wide range in He content, together with consistently radiogenic He-isotope values in Udachnaya peridotites suggests that crustal-derived fluids have incongruently metasomatized segments of the Siberian SCLM, whereas high 3 He/ 4 He values in Obnazhennaya peridotites show that this section of the SCLM has been overprinted by Permo-Triassic (plume-derived) basaltic fluids. Indeed, the stark contrast between pre-and post-plume 3 He/ 4 He ra-tios in peridotite xenoliths highlights the potentially powerful utility of He-isotopes for differentiating between various types of metasomatism (i.e., crustal versus basaltic fluids).
DS201707-1300
2017
Magna, T.Ackerman, L., Magna, T., Rapprich, V., Upadhyay, D., Kratky, O., Cejkova, B., Erban, V., Kochergina, Y.V., Hrstka, T.Contrasting petrogenesis of spatially related carbonatites from Samalpatti and Sevattur, Tamil Nadu, India.Lithos, Vol. 284-285, pp. 257-275.Indiacarbonatite - Samalpatti, Sevattur

Abstract: Two Neoproterozoic carbonatite suites of spatially related carbonatites and associated silicate alkaline rocks from Sevattur and Samalpatti, south India, have been investigated in terms of petrography, chemistry and radiogenic–stable isotopic compositions in order to provide further constraints on their genesis. The cumulative evidence indicates that the Sevattur suite is derived from an enriched mantle source without significant post-emplacement modifications through crustal contamination and hydrothermal overprint. The stable (C, O) isotopic compositions confirm mantle origin of Sevattur carbonatites with only a modest difference to Paleoproterozoic Hogenakal carbonatite, emplaced in the same tectonic setting. On the contrary, multiple processes have shaped the petrography, chemistry and isotopic systematics of the Samalpatti suite. These include pre-emplacement interaction with the ambient crustal materials with more pronounced signatures of such a process in silicocarbonatites. Calc-silicate marbles present in the Samalpatti area could represent a possible evolved end member due to the inability of common silicate rocks (pyroxenites, granites, diorites) to comply with radiogenic isotopic constraints. In addition, Samalpatti carbonatites show a range of C–O isotopic compositions, and ?13CV-PDB values between + 1.8 and + 4.1‰ found for a sub-suite of Samalpatti carbonatites belong to the highest values ever reported for magmatic carbonates. These heavy C–O isotopic signatures in Samalpatti carbonatites could be indicative of massive hydrothermal interaction with carbonated fluids. Unusual high-Cr silicocarbonatites, discovered at Samalpatti, seek their origin in the reaction of pyroxenites with enriched mantle-derived alkali-CO2-rich melts, as also evidenced by mantle-like O isotopic compositions. Field and petrographic observations as well as isotopic constraints must, however, be combined with the complex chemistry of incompatible trace elements as indicated from their non-uniform systematics in carbonatites and their individual fractions. We emphasise that, beside common carriers of REE like apatite, other phases may be important for incompatible element budgets, such as mckelveyite–(Nd) and kosmochlor, found in these carbonatites. Future targeted studies, including in-situ techniques, could help further constrain temporal and petrologic conditions of formation of Sevattur and Samalpatti carbonatite bodies.
DS201709-1976
2017
Magna, T.Czupponi, G., Magna, T., Benk, Z., Rapprich, V., Ott, U.Noble gases in Indian carbonatites.Goldschmidt Conference, abstract 1p.Indiacarbonatites

Abstract: We have studied noble gases in carbonates and apatites from three carbonatites of South India, namely Hogenakal (2400 Ma), Sevattur (770 Ma) and Khambamettuu (523 Ma) by vacuum crushing. Apatite has also been analysed by pyrolysis. Vacuum crushing mostly releases the trapped gas components. The ratios 21Ne/20Ne, 22Ne/20Ne and 40Ar/36Ar increase with progressive crushing due to preservation of different composition gases in smaller inclusions released in later steps. This heterogeneity of isotopic composition of fluid inclusions is a consequence of the involvement of magmas carrying different noble gas signatures. The inclusions with lower ratios suggest the presence of a subducted atmospheric component, while the higher 21Ne/20Ne, 22Ne/20Ne and 40Ar/36Ar can be attributed to the presence of an enriched lithospheric mantle component. In addition, very minor trapped gases from less degassed, deeper mantle may also be present but overprinted by lithospheric and/or nucleogenic components. We propose that these carbonatites were generated only in an advanced stage of magmatism when this lithospheric component overwhelmed any contribution from the deeper mantle source. The lithospheric mantle underwent enrichment during an ancient subduction process through mantle metasomatism manifested in nucleogenic/radiogenic isotopic ratios of 21Ne/20Ne, 22Ne/20Ne and 40Ar/36Ar. The apatites analysed by pyrolysis clearly show nucleogenic 21Ne from 18O(?,n) reaction. We have demonstrated the potential of using U,Th–21Ne systematics as a thermo-chronometer in conjunction with the established U,Th–4He and U–136Xe clocks. While for Hogenakal, the U,Th–21Ne age of 845 ± 127 Ma is in agreement with the age of emplacement of other adjacent younger carbonatites, syenites and alkali granites, for the Sevattur apatite (738 ± 111 Ma) it indicates the crystallisation age.
DS201709-2025
2017
Magna, T.Magalhaes, N., Magna, T., Rapprich, V., Kratky, O., Farquhar, J.Sulfur isotope systematics in carbonatites from Sevattur and Samalpatti, S India.Goldschmidt Conference, abstract 1p.Indiacarbonatites, Sevattur, Samalpatti

Abstract: We report preliminary data for sulfur isotopes from two spatially related Neoproterozoic carbonatite complexes in Tamil Nadu, S India, with the aim of getting further insights into their magmatic and/or post-emplacement histories [1]. The major sulfide phase in these rocks is pyrite, with minor chalcopyrite, whereas sulfate occurs as barite. A bimodal distribution of G34Ssulfide is found for Samalpatti (13.5 to 14.0‰), and Sevattur (?2.1 to 1.4‰) carbonatites. A significantly larger range of G34Ssulfide values is found for the associated Samalpatti silicate rocks (?5.2 to 7.4‰) relative to Sevattur pyroxenites and gabbros (?1.1 to 2.1‰). High G34Ssulfide values for Samalpatti carbonatites are unsual [2,3] but could reflect hydrothermal post-emplacement modification [1] of S isotopes. The low G34Ssulfide values for Sevattur may represent a mantle source signature. The G34Ssulfate is uniformly positive for both complexes, with most data falling in a narrow range (5.7 to 7.8‰) and one datum for a pyroxenite yielding more positive G34Ssulfate = 13.3‰. Data for '33S varies outside of analytical uncertainty (?0.07 to 0.04‰), indicating contribution from a source with a surface-derrived component. The small range of '33S values does not allow us to determine whether these sources contain S fractionated by biogeochemical (mass-dependent) or photochemical (mass-independent, pre GOE) processes. Data for '36S is positive, and varies within uncertainty (0.28 ± 0.15‰). Variations of this magnitude have been observed in other localities, and are not diagnostic of any unique source or process. The sulfur isotope data imply addition of crustal sulfur to Samalpatti. In contrast, sulfur from Sevattur has a mantle-like G34S but '33S with anomalous character. These observations support the idea of a different evolutionary story for these complexes, possibly more complex than previously thought.
DS201709-2026
2017
Magna, T.Magna, T., Wittke, A., Gussone, N., Rapprich, V., Upadhyay, D.Calcium isotope composition of carbonatites - a case study of Sevattur and Samalpatti, S. India.Goldschmidt Conference, abstract 1p.Indiacarbonatites

Abstract: Calcium isotope compositions are presented for two suites of carbonatites and associated alkaline silicate rocks from Neoproterozoic Sevattur and Samalpatti complexes in Tamil Nadu, South India. Despite their geographic proximity, the mean G44/40Ca values are different for Sevattur (G44/40Ca = 0.69 r 0.10‰, n = 7) and Samalpatti (0.81 r 0.16‰, n = 5). The former suite is derived from an enriched mantle source without significant post-emplacement modifications [1] and its Ca isotope composition falls to the lower end of Ca isotope range reported for mantle-derived rocks [2]. Some carbonatites from Samalpatti show a 44Ca-enriched signature which could reflect large-scale low-temperature modification, recognized also by their 13C–18O-enriched isotope systematics and sizeable loss of REE, when compared to pristine carbonatites from the area [1]. This is also consistent with albite–epidote metasomatic sample and shistose pyroxenite from Samalpatti, both showing a 44Ca-depleted signature. Leaching experiments confirm a systematic G44/40Ca offset with isotopically light carbonate relative to bulk sample [also 3]. Pyroxenites from Samalpatti are isotopically heavier than accompanying unmodified carbonatites and their G44/40Ca values fall into the mantle range. In contrast, pyroxenite and phosphate from Sevattur have a G44/40Ca value identical with associated carbonatites, indicating a homogeneous mantle source for the latter complex. For K-rich syenites and monzonites, 40K-decay corrections need to be considered for the intrinsic mass-dependent isotope fractionations considering the Neoproterozoic age and high K/Ca character of some samples.
DS201709-2047
2017
Magna, T.Rapprich, V., Pecskay, Z., Magna, T., Mikova, J.Age disparity for spatially related Sevattur and Samalpatti carbonatite complexes.Goldschmidt Conference, abstract 1p.Indiacarbonatites

Abstract: The Neoproterozoic Sevattur and Samalpatti alkaline– carbonatite complexes in S India were supposedly emplaced into regional metagranite at ~800 Ma [1]. Both complexes are close to each other (~4 km apart), with a similar NE–SW elongated oval shape arranged along NE–SW trending lineament formed by the Koratti–Attur tectonic zone [2]. Both complexes share a similar setting with central syenite intrusion mantled with a discontinuous ring and/or crescentshaped suites of carbonatites, pyroxenites, gabbros, and dunites. In contrast to identical tectonic position and similar structure, the two complexes differ significantly in geochemistry and Sr–Nd–Pb–O–C isotope compositions. The Sevattur suite is derived from an enriched mantle source without significant post-emplacement modification whilst extensive hydrothermal overprint by crustal fluids must have occurred to result in the observed 13C–18O-enriched systematics reported for the Samalpatti carbonatites [3]. Some Samalpatti pyroxenites, though, show a clear mantle signature [3]. We report preliminary K–Ar age-data, that indicate a prolonged period of the magmatic activity in this area. Sevattur gabbro and pyroxenite (both Bt-fraction) as well as one Samalpatti Cr-rich silicocarbonatite (Amp-fraction) yielded the range of ages at 700–800 Ma, consistent with previous reports [see 3 for details]. The new K–Ar data from syenites display significantly younger ages of 560–576 Ma for Samalpatti and 510–540 Ma for Sevattur, regardless of the mineral fraction used (Bt or Kfs). The K–Ar results are being supplemented by systematic U–Pb analyses of zircons. If proven true, the age disparity would have profound consequences on our understanding of carbonatite evolution.
DS201710-2209
2017
Magna, T.Ackerman, L., Slama, J., Haluzova, E., Magna, T., Rapprich, V., Kochergin, Y., Upadhyay, D.Hafnium isotope systematics of carbonatites and alkaline silicate rocks from south and west India.Goldschmidt Conference, 1p. AbstractIndiadeposit - Amba Dongar
DS201801-0001
2017
Magna, T.Ackerman, L., Magna, T., Rapprich, V., Upadhyay, D., Kratky, O., Cejkova, B., Erban, V., Kochergina, Y.V., Hrstka, T.Contrasting petrogenesis of spatially related carbonatites from Samalpatti and Sevattur, Tamil Nadu, India: insights from trace element and isotopic geochemistry.Carbonatite-alkaline rocks and associated mineral deposits , Dec. 8-11, abstract p. 31-33.Indiadeposit - Samalpatti, Sevattur

Abstract: The Tamil Nadu region in southern India hosts several carbonatite bodies (e.g., Hogenakal, Samalpatti, Sevattur, Pakkanadu-Mulakkadu) which are closely associated with alkaline silicate rocks such as syenites, pyroxenites or dunites (e.g, Kumar et al., 1998; Schleicher et al., 1998; Srivastava, 1998). This is in contrast to the carbonatite occurrences in north-western India associated with the Deccan Trap basalts (e.g., Amba Dongar) or Proterozoic Newania dolomitic carbonatites. We have studied two, spatially related, Neoproterozoic carbonatite-silico(carbonatite) suites in association with alkaline silicate rocks (e.g., pyroxenite, gabbro) from Sevattur and Samalpatti in terms of petrography, chemistry and radiogenic-stable isotopic compositions in order to provide constraints on their genesis and evolution. In these two bodies, several different carbonatite types have been reported previously with striking differences in their trace element and isotopic compositions (Srivastava, 1998; Viladkar and Subramanian, 1995; Schleicher et al., 1998; Pandit et al., 2002). Collected data for previously poorly studied calcite carbonatites from the Sevattur representing the first carbonatite magmas on this locality, indicate similar geochemical characteristics to those of dolomitic carbonatites, such as high LREE/HREE ratios, very high Sr and Ba contents, large amounts of apatite and magnetite, identical Sr-Nd-C-O isotopic compositions. Thus, they were derived from an enriched mantle source without significant post-emplacement modifications through crustal contamination and hydrothermal overprint, in agreement with previous studies (e.g., Schleicher et al., 1998). Detailed microprobe analyses revealed that high levels of some incompatible elements (e.g., REE, Y, Sr, Ba) cannot be accounted by matrix calcite hosting only significant amounts of SrO (~0.6-1.2 wt.%). On the other hand, abundant micro- to nano-scale exsolution lamellae and/or inclusions of mckelveyite-(Nd) appear to host a significant fraction of LREE in parallel with apatite. Distribution of Sr is most likely influenced also by common but heterogeneously dispersed barite and strontianite. Newly acquired as well as detailed inspection of available geochemical data permits distinguish two different types of carbonatites in Samalpatti: (1) Type I similar to Sevattur carbonatites in terms of mineralogy, trace element and radiogenic-stable isotopic compositions and (2) Type II with remarkably low concentrations of REE and other incompatible trace elements, more radiogenic Sr isotopic compositions and extremely variable C–O isotopic values. The petrogenesis of the Type II seems to be intimately associated with the presence of silicocarbonatites and abundant silicate mineral domains. Instead of liquid immiscible separation from a silicate magma, elevated SiO2 contents observed in silico-carbonatites may have resulted from the interaction of primary carbonatitic melts and crustal rocks prior to and/or during magma emplacement. Arguments for such hypothesis include variable, but radiogenic Sr isotopic compositions correlated with SiO2 and other lithophile elements (e.g., Ti, Y, Zr, REE). Calc-silicate marbles present in the Samalpatti area could represent a possible evolved crustal end member for such process due to the inability of common silicate rocks (pyroxenites, granites, diorites) to comply with radiogenic isotopic constraints. The wide range of C-O isotopic compositions found in Samalpatti carbonatites belong to the highest values ever reported for magmatic carbonates and can be best explained by massive hydrothermal interaction with carbonated fluids. Unusual high-Cr silicocarbonatites were discovered at Samalpatti forming centimetre to decimetre-sized enclaves enclosed in pyroxenites with sharp contacts at hand specimen scale. Detailed microprobe analyses revealed peculiar chemical compositions of the Mgamphibole with predominantly sodic composition embaying and replacing Na-Cr-rich pyroxene (kosmochlor), accompanied by the common presence of Cr-spinel and titanite. Such association have been reported for hydrous metasomatism by Na-rich carbonatitic melts at upper mantle conditions (Ali and Arai, 2013). However, the mineralogy and the mode of occurrence of Samalpatti Mg–-r-rich silicocarbonatites argue against such origin. We explain the petrogenesis of these rocks through the reaction of pyroxenites with enriched mantle-derived alkali-CO2-rich melts, as also evidenced by mantle-like O and Hf isotopic compositions.
DS201801-0035
2017
Magna, T.Magna, T., Rapprich, V., Wittke, A., Gussone, N., Upadhyay, D., Mikova, J., Pecskay, Z.Calcium isotope systematics and K-Ar and U-Pb temporal constraints on the genesis of Sevattur Samalpatti carbonatite silicate alkaline complexes.Carbonatite-alkaline rocks and associated mineral deposits , Dec. 8-11, abstract p. 34-35.Indiadeposit - Samalpatti, Sevattur

Abstract: We present the first systematic survey of Ca isotope compositions in carbonatites and associated silicate rocks from Samalpatti and Sevattur, two Neoproterozoic complexes in Tamil Nadu, south India. Despite their close geographic proximity, their genesis and post-emplacement histories differ (Ackerman et al. 2017). The Sevattur complex appears to have been derived from an enriched mantle source with a limited post-magmatic disturbance. In contrast, carbonatites from Samalpatti show a record of extensive late-stage post-magmatic overprint, also apparent from unusually heavy C-O isotope compositions in a sub-suite of carbonatites (Ackerman et al. 2017). The mean ?44/40Ca = 0.69 ± 0.10‰ is slightly lighter than the average of fertile, unmetasomatized peridotites at ?44/40Ca = 0.95 ± 0.05‰ (Kang et al. 2017). This difference may attest to the general difference between carbonates and silicates (see Kang et al. 2017). It could also reflect Ca isotope fractionation between isotopically heavy silicate and isotopically light carbonate (e.g., John et al. 2012), though to a somewhat minor extent. This is supported by leaching experiments in this study where the extent of silicate-carbonate fractionation (44/40Casilicate-carbonate) has been investigated. The values at ~0.1-0.2‰ are expectedly lower than those reported earlier (~0.6‰; John et al. 2012) and may reflect high-temperature Ca isotope fractionation. The variability in ?44/40Ca values of carbonatites and silico-carbonatites from the Samalpatti complex is larger (0.70- 1.14‰) and appears to be in accord with extensive post-emplacement disturbance. Significant loss of REE and 13C-18O-enriched signature are combined with high ?44/40Ca values, which could reflect massive exchange with metasomatic aqueous fluids. The 40Kdecay correction was applied to K-rich rocks (syenites, monzonites). Given the antiquity of the complex dated at ca. ~800 Ma (Schleicher et al. 1997) and considering high-K/Ca character of some rocks, the resulting ?44/40Ca800 Myr correction was up to ~+1.2‰. In this regard, it is crucial to constrain the age history of the entire region. The nearby Hogenakal carbonatite body was dated at ~2.4 Ga which is much older than Rb-Sr and Sm-Nd age of Sevattur (Kumar et al. 1998) from the same fault system. We have acquired K-Ar mineral (K-feldspar, biotite, amphibole) and U-Pb zircon data from Sevattur and Samalpatti. The K-Ar ages span a range between ~800 and ~510 Ma (~800 Ma for amphiboles and biotites from silico-carbonatites and mafic silicate rocks and ~570-510 Ma for K-feldspars and biotites from syenites), dating two high-grade regional tectono-thermal overprint events, documented earlier. The complex nature of this process is indicated by concordant U-Pb zircon age at ~2.5 Ga yielded for a melatonalite, for which K-Ar biotite age of ~802 Ma was measured. This fits into the age bracket of basement of the Eastern Dharwar Craton. The age distribution bimodality at ~2.5 Ga and ~800 Ma has been found for several other samples, suggesting a pulsed thermal history of the area, associated with a significant overprint by fluids likely derived from the local crust. Particularly high U concentrations in zircons (thousands ppm), combined with a range of K-Ar ages, attest to such multi-episodic history.
DS201801-0048
2017
Magna, T.Polak, L., Ackerman, L., Rapprich, V., Magna, T.Platinum group element and rhenium osmium geochemistry of selected carbonatites from India, USA and East africa.Carbonatite-alkaline rocks and associated mineral deposits , Dec. 8-11, abstract p. 22-23.India, United States, Africa, East Africacarbonatites

Abstract: Carbonatites and associated alkaline silicate rocks might have potential economic impact for a large variety of metals such as Cu, Ni, Fe and platinum-group elements (PGE - Os, Ir, Ru, Pd, Pt) as it is demonstrated in South Africa (Phalaborwa; Taylor et al. 2009) or Brazil (Ipanema; Fontana 2006). In addition, determined PGE contents along with Re-Os isotopic compositions may also provide important information about PGE fractionation during the genesis of upper mantle-derived carbonatitic melts and nature of their sources. Nevertheless, the existing PGE data for carbonatites are extremely rare, limited mostly to Chinese localities and they are not paralleled by Re-Os isotopic data (Xu et al. 2008). Therefore, in this study, we present the first complete PGE datasets together with Re-Os determinations for a suite of selected carbonatite bodies worldwide. We have chosen eight carbonatite sites with different alkaline rock association, age and geotectonic position. Among these, the youngest samples are from East African rift system and include Oldoinyo Dili, Tanzania with an age spanning from ~0 to 45 Ma; same as Tororo and Sukulu in Uganda (Woolley and Kjarsgaard 2008). These carbonatites are in association with pyroxenites and nepheline syenites. Another young carbonatitic complex is Amba Dongar in west India with Cretaceous age of ~65 Ma associated with alkaline volcanic rocks such as trachybasalts within Deccan Traps (Sukheswala and Udas 1963). Proterozoic bodies are represented by Iron Hill, USA carbonatites associated with pyroxenite, melitolite and ijolite with age ranging from ~520 to 580 Ma (Nash 1972). These carbonatites are famous for their intensive and varied fenitization. Last and the oldest carbonatites in this study comes from Samalpatti and Sevattur, South India having the age of ~800 Ma (Schleicher et al. 1997) and outcropping as small bodies within alkaline rocks such as pyroxenite, syenite and gabbro. The PGE concentrations and Re-Os isotopic ratios were determined by standard methods consisting of decarbonatization using HCl, decomposition of samples in Carius Tubes in the presence of reverse aqua regia and spikes (isotopic dilution), separation of Os by CHCl3 followed by N-TIMS measurements and Ir, Ru, Pd, Pt, Re isolation by anion exchange chromatography followed by ICP-MS measurements. All analysed carbonatites exhibit extremely low PGE contents (? PGE up to 1 ppb), even in the samples with high S contents (up to 1.5 wt. %). Such values are much lower than other determined so far for upper mantle-derived melts such as basalts, komatiites, etc. (Day et al. 2016). Such signatures indicate very low partitioning of PGE into carbonatitic melts and/or early separation of PGE-bearing fraction. Elements from iridium-group I-PGE; Os, Ir and Ru; mostly < 0.1 ppb) are distinctly lower compared to palladiumgroup elements and Re (PPGE; Pt, Pd, Re; mostly > 0.1 ppb) with some rocks being largely enriched in Re (up to ~6 ppb). Most of the analysed carbonatites exhibit progressive enrichment from Os to Re and consequently, PdN/ReN < 0.1 except south India carbonatites and associated alkaline rocks (> 0.30). Rocks analysed so far for Os have OsN/IrN up to 6.2 that might suggest that the carbonatites might concentrate Os over Ir. The highest HSEtot contents have been found in Mg-Cr-rich silicocarbonatites from South India (up to 40 ppb) and taking into account their only slightly radiogenic 187Os/188Os ratios (0.14-0.57), these rocks represents mixture of CO2-rich alkaline mantle melts and country rocks. Very high concentrations of HSE have been also found in magnetite separated from Fe-carbonatite from Amba Dongar, India (0.2-0.5 ppb of I-PGE and 0.9-9 ppb of P-PGE). The 187Os/188Os ratios determined so far for carbonatites from South India vary from 0.24 to 6.5 and calculated ?Os values range from +100 up to +5000. Such wide range of values suggest extremely heterogenous source of the melts and/or possible contamination by 187Os-rich crustal materials.
DS201909-2094
2019
Magna, T.Tappe, S., Burness, S., Smart, K., Magna, T., Stracke, A.Views of plate tectonics and mantle metal budgets from alkaline and carbonate magmas.Goldschmidt2019, 1p. AbstractGlobalalkaline rocks

Abstract: Low-volume alkaline silicate and carbonate magmas are products of volatile-controlled incipient melting processes in the Earth’s mantle. Although this form of melting is ubiquitous beneath the thick and cold portions of continental lithosphere, such melts rarely reach the Earth’s surface due to a combination of their small volumes, reactive nature, and great depths of origin. In spite of being rare at surface, the impact of alkaline and carbonate magmatism on the dynamic stability of mantle lithosphere and its metal endowment may be disproportionately large, but it is difficult to grasp in the absence of spatial and temporal constraints on melt mobility. We review evidence from major alkaline and carbonatite provinces for metasomatic overprinting of the underlying continental mantle lithosphere, and evaluate how these processes influenced plate tectonic evolution in these regions. Key examples from Greenland and Africa show that metasomatic weakening of mantle lithosphere by pervasive alkaline and carbonate melts is frequently the first step in continent fragmentation ultimately leading to supercontinent dispersal. A major obstacle in identifying carbonate melt metasomatized mantle is the use of differentiated ‘surface’ carbonatite compositions as proxies for geochemical processes operating at great depths. We assess the robustness of some of the classic geochemical proxies, such as Ti/Eu and Zr/Sm, and identify new promising fingerprints of passing carbonate melts in the deep mantle lithosphere. New evidence from the Kaapvaal craton, one of world’s best endowed metallogenic provinces, shows that redox- and volatile-controlled alkaline melting events can effectively mobilize sulphide-hosted PGE and base metal budgets from eclogite components within the thick mantle lithosphere. Such precursor alkaline magmatic events, heralding the formation of major continental rifts and mantle plume impingement, can enhance the metal contents of subsequent asthenosphere-derived mafic magmas, thereby upgrading oreforming potential. However, economic metal deposits only form when geologic conditions during magma emplacement in the crust are favorable, with mantle metal budgets being less critical.
DS201910-2241
2019
Magna, T.Ackerman, L., Polak, L., Magna, T., Rapprich, V., Jana, D., Upadhyay, D.Highly siderophile element geochemistry and Re-Os isotopic systematics of carbonatites: insights from Tamil Nadu, India.Earth and Planetary Science letters, Vol. 520, pp. 175-187.Indiacarbonatites

Abstract: Carbonatite metasomatism has been widely implicated for worldwide mafic mantle suites but so far, no combined data have been available for highly siderophile element systematics (HSE - Os, Ir, Ru, Pt, Pd, Re) and Re-Os isotopic compositions in carbonatites themselves. We present the first systematic survey of the HSE and Re-Os isotopic compositions in a suite of well-characterized Neoproterozoic carbonatites, silicocarbonatites and associated silicate rocks (pyroxenites, monzogabbros, syenites) from south India in order to place constraints on the HSE systematics in carbonatite magmas, anchoring possible mantle sources of carbonatites and relationship to the ambient crustal lithologies as well as preliminary constraints on carbonatite metasomatism in Earth's mantle. The most plausible explanation for generally low HSE contents in calciocarbonatites from Tamil Nadu (?HSE < 1.22 ppb) involves a low-degree (<1%) partial melting of the mantle source producing sulfur-saturated carbonatitic magmas leaving behind sulfide phases retaining HSE. The new data also indicate a strong FeO control on the distribution of Os and Pt during segregation of carbonatite melt from its enriched mantle source and/or melt differentiation. The combined 187Re/188Os values (from 0.10 to 217), 187Os/188Os ratios (0.186-10.4) and initial ?Os values back-calculated to 800 Ma (from +0.1 to +6052) predict that most Tamil Nadu calciocarbonatites were plausibly derived from a carbonated peridotite source with <10% recycled component. This model would thus provide significant constraints on the origin/source of carbonatites, irrespective of their post-emplacement history. The unusual, volumetrically rare, Mg-Cr-rich silicocarbonatites (?HSE = 14-41 ppb) display almost identical HSE patterns with those of host pyroxenites and predominantly high Pt (up to 38 ppb), the origin of which remains unknown. Positive co-variations between Pt, Pd and Re, and the well-developed positive correlation between Pt and MgO in these Mg-Cr-rich silicocarbonatites argue for a source coming predominantly from the upper mantle. The Re-Os isotopic systematics agree with direct incorporation of enriched mantle-derived material into parental melts but variable incorporation of potassium-rich crustal materials is evidenced by highly positive ?Os800 Ma values for a sub-suite of Mg-Cr-rich silicocarbonatites, indicating intense fenitization. The highly radiogenic Os isotopic compositions of monzogabbros and a syenite argue for their derivation from crustal lithologies with no or only negligible contribution of mantle material. Collectively, low Ir, Ru, Pt and Pd contents found in the Tamil Nadu carbonatites appear to indicate the incapability to significantly modify the total budget of these elements in the Earth's mantle during carbonatite metasomatism. In contrast, very high Re/Os ratios found in some of the analyzed carbonatites, paralleled by extremely radiogenic 187Os/188Os signature, can produce large modification of the Re-Os isotopic composition of mantle peridotites during carbonatite melt percolation when high melt/rock ratios are achieved.
DS201911-2543
2019
Magna, T.Magna, T., Viladkar, S., Rappirich, V., Pour, O., Cejkova, B.Nb-V enriched sovites of the northeastern and eastern part of the Amba Dongar carbonatite ring dike, India - a reflection of post emplacement hydrothermal overprint.Chemie der Erde, in press available 11p. Indiadeposit - Amba Dongar
DS202102-0204
2020
Magna, T.Magna, T., Viladar, S., Rapprich, V., Pour, O., Hopp, J., Cejkova, B.Nb-V enriched sovites of the northeastern and eastern part of the Amba Dongar carbonatite ring dike, India - a reflection of post-emplacement hydrothermal overprint?Geochemistry, Vol. 80, doi.org/10.1016 /j.chemer.2019 .125534 11p. PdfIndiadeposit - Amba Dongar

Abstract: Wakefieldite-(Ce,La) and vanadinite in coarse-grained calciocarbonatites (sovites) are for the first time reported from the northeastern part of the worldwide largest fluorite deposit at the Amba Dongar carbonatite ring dike, India. Sovite in this part of the carbonatite ring dike is rich in pyrochlore, calcite and magnetite. Pyrochlore makes up almost 50% of some sovite samples and shows core-to-rim compositional changes. The core of pyrochlore consists of primary fluorcalciopyrochlore with high F and Na contents while the margins gained elevated amounts of Pb, La and Ce with the associated loss of F and Na due to circulation of hydrothermal solutions. The presence of wakefieldite-(Ce,La) and vanadinite points to an exceptionally high V abundance in hydrothermal solutions formed towards the end of the carbonatite magma activity. This investigation thus opens new promising areas for Nb and REE prospection in the eastern part of the Amba Dongar carbonatite body.
DS202108-1294
2021
Magna, T.Krmicek, L., Magna, T., Chalapathi Rao, Pandey, A.Lithium isotopes in kimberlites, lamproites and lamprophyres as tracers of source components and processes related to supercontinent cycles.Geological Society of London Special Publications, doi:10.1144/SP513-2021-60geodynamics

Abstract: Our pilot study reveals potential fingerprints of Li isotopes recorded in the Mesoproterozoic (?1.4-1.1 Ga) kimberlites, lamproites and lamprophyres from the Eastern Dharwar Craton and Paleocene (62 Ma) orangeite from the Bastar Craton in India. The new data are interpreted in the context of available Li isotope composition of lamproitic to lamprophyric rocks occurring in Variscan (Bohemian Massif) and Alpine-Himalayan (SW Tibet) orogenic belts formed in response to Gondwana-Pangea amalgamation and break-up. As a result of supercontinents development, kimberlites from the Eastern Dharwar Craton and ‘orangeite’ from the Bastar Craton show clear presence of a component with a heavy Li isotope signature (?7Li up to 9.7‰) similar to an ancient altered oceanic crust, whereas the Eastern Dharwar Craton lamproites (2.3-6.3‰) and lamprophyres (3.3-6.7‰) show Li isotope signatures indicative of a dominant contribution from heterogeneous lithospheric mantle. Variscan lamprophyric to lamproitic rocks and post-collisional mantle-derived (ultra)potassic volcanic rocks from SW Tibet, i.e., rocks from the orogenic belts outside the cratonic areas, are characterized by a clear Li isotope shift towards isotopically lighter component (?7Li as low as -9.5‰) comparable with the involvement of an evolved continental crust and high-pressure metamorphic rocks in their orogenic mantle source. Such components with isotopically light Li are strikingly missing in the source of cratonic kimberlites, lamproites and lamprophyres.
DS200512-0624
2005
Magnani, M.B.Levander, A., Zelt, C., Magnani, M.B.Crust and upper mantle velocity structure of the Southern Rocky Mountains from the Jemez Lineament to the Cheyenne Belt.American Geophysical Union, Geophysical Monograph, No. 154, pp. 293-308.United States,Wyoming, Colorado PlateauGeophysics - seismics, tectonics
DS1994-1087
1994
Magnavita, L.P.Magnavita, L.P., Davison, I., Kusznir, N.J.Rifting, erosion and uplift history of the Reconcavo Tucano Jatoba Rift, northeast Brasil.Tectonics, Vol. 13, No. 2, Apr. pp. 367-88.BrazilTectonics
DS1940-0157
1947
Magnee, I. DE.Magnee, I. DE.Presence de Kimberlite dans la Zone Diamantifere de BakwangaSoc. Geol. Belge Bulletin., Vol. 56, No. 1-2, PP. 97-108;Democratic Republic of Congo, Central AfricaKimberlite, Geology
DS1940-0213
1949
Magnee, I. DE.Magnee, I. DE.Kimberlite Discovery in the Diamond Fields of BakwangaGems And Gemology, Vol. 6, No. 5, PP. 131-135.Democratic Republic of Congo, Central AfricaGeology
DS1950-0031
1950
Magnee, I. DE.Magnee, I. DE.Deliniation Geo-electrique du Premiere Pipe de Kimberlite Decouvert dans Les Champs Diamantiferes du Kasai (congo Belge).Institute of Geological Sciences 18TH. SESSION., PT. 5, PP. 52-58.Democratic Republic of Congo, Central AfricaKimberlite, Geophysics, Ground Electromagnetic
DS201709-2027
2017
Magni, V.Magni, V., Allen, M.B., van Hunen, J., Bouihol, P.Continental underplating after slab break-off.Earth and Planetary Science Letters, Vol. 474, pp. 59-67.Mantle, India-Eurasiasubduction

Abstract: We present three-dimensional numerical models to investigate the dynamics of continental collision, and in particular what happens to the subducted continental lithosphere after oceanic slab break-off. We find that in some scenarios the subducting continental lithosphere underthrusts the overriding plate not immediately after it enters the trench, but after oceanic slab break-off. In this case, the continental plate first subducts with a steep angle and then, after the slab breaks off at depth, it rises back towards the surface and flattens below the overriding plate, forming a thick horizontal layer of continental crust that extends for about 200 km beyond the suture. This type of behaviour depends on the width of the oceanic plate marginal to the collision zone: wide oceanic margins promote continental underplating and marginal back-arc basins; narrow margins do not show such underplating unless a far field force is applied. Our models show that, as the subducted continental lithosphere rises, the mantle wedge progressively migrates away from the suture and the continental crust heats up, reaching temperatures >900?°C. This heating might lead to crustal melting, and resultant magmatism. We observe a sharp peak in the overriding plate rock uplift right after the occurrence of slab break-off. Afterwards, during underplating, the maximum rock uplift is smaller, but the affected area is much wider (up to 350 km). These results can be used to explain the dynamics that led to the present-day crustal configuration of the India–Eurasia collision zone and its consequences for the regional tectonic and magmatic evolution.
DS201710-2243
2017
Magni, V.Magni, V.Plate tectonics: crustal recycling evolution.Nature Geoscience, Vol. 10, 9, pp. 623-624.Mantleslab break-off

Abstract: The processes that form and recycle continental crust have changed through time. Numerical models reveal an evolution from extensive recycling on early Earth as the lower crust peeled away, to limited recycling via slab break-off today.
DS201711-2513
2017
Magni, V.Freeburn, R., Bouilhol, P., Maunder, B., Magni, V., van Hunen, J.Numerical models of the magmatic processes induced by slab breakoff.Earth and Planetary Science Letters, Vol. 478, pp. 203-213.Mantlesubduction

Abstract: After the onset of continental collision, magmatism often persists for tens of millions of years, albeit with a different composition, in reduced volumes, and with a more episodic nature and more widespread spatial distribution, compared to normal arc magmatism. Kinematic modelling studies have suggested that slab breakoff can account for this post-collisional magmatism through the formation of a slab window and subsequent heating of the overriding plate and decompression melting of upwelling asthenosphere, particularly if breakoff occurs at depths shallower than the overriding plate. To constrain the nature of any melting and the geodynamic conditions required, we numerically model the collision of two continental plates following a period of oceanic subduction. A thermodynamic database is used to determine the (de)hydration reactions and occurrence of melt throughout this process. We investigate melting conditions within a parameter space designed to generate a wide range of breakoff depths, timings and collisional styles. Under most circumstances, slab breakoff occurs deeper than the depth extent of the overriding plate; too deep to generate any decompressional melting of dry upwelling asthenosphere or thermal perturbation within the overriding plate. Even if slab breakoff is very shallow, the hot mantle inflow into the slab window is not sustained long enough to sufficiently heat the hydrated overriding plate to cause significant magmatism. Instead, for relatively fast, shallow breakoff we observe melting of asthenosphere above the detached slab through the release of water from the tip of the heating detached slab. Melting of the subducted continental crust during necking and breakoff is a more common feature and may be a more reliable indicator of the occurrence of breakoff. We suggest that magmatism from slab breakoff alone is unable to explain several of the characteristics of post-collisional magmatism, and that additional geodynamical processes need to be considered when interpreting magmatic observations.
DS201904-0758
2019
Magni, V.Maunder, B. Hunen, J., Bouihol, P., Magni, V.Modeling slab temperature: a reevaluation of the thermal parameter.Geochemistry, Geophysics, Geosystems, Vol. 20, 2, pp. 673-687.MantleThermometry

Abstract: We reevaluate the effects of slab age, speed, and dip on slab temperature with numerical models. The thermal parameter ? = t v sin ?, where t is age, v is speed, and ? is angle, is traditionally used as an indicator of slab temperature. However, we find that an empirically derived quantity, in which slab temperature T ? log (t?av?b) , is more accurate at depths <120 km, with the constants a and b depending on position within the slab. Shallower than the decoupling depth (~70-80 km), a~1 and b~0, that is, temperature is dependent on slab age alone. This has important implications for the early devolatilization of slabs in the hottest (youngest) cases and for shallow slab seismicity. At subarc depths (~100 km), within the slab mantle, a~1 and b~0 again. However, for the slab crust, now a~0.5 and b~1, that is, speed has the dominant effect. This is important when considering the generation of arc magmatism, and in particular, slab melting and the generation of slab?derived melange diapirs. Moving deeper into the Earth, the original thermal parameter performs well as a temperature indicator, initially in the core of the slab (the region of interest for deep water cycling). Finally, varying the decoupling depth between 40 and 100 km has a dominant effect on slab temperatures down to 140?km depth, but only within the slab crust. Slab mantle temperature remains primarily dependent on age.
DS202109-1469
2021
Magnus, S.Good, D.J., Hollings, P., Dunning, G., Epstein, R., McBride, J., Jedemann, A., Magnus, S., Bohav, T., Shore, G.A new model for the Coldwell Complex and associated dykes of the Midcontinent Rift, Canada.Journal of Petrology, Vol. 62, 7, 10.1093/petrology/ega036Canadadeposit - Coldwell

Abstract: Mafic intrusions on the NE shoulder of the Midcontinent Rift (Keweenawan LIP), including Cu-PGE mineralized gabbros within the Coldwell Complex (CC), and rift parallel or radial dykes outside the CC are correlated based on characteristic trace element patterns. In the Coldwell Complex, mafic rocks are subdivided into four groups: (1) early metabasalt; (2) Marathon Series; (3) Layered Series; (4) Geordie-Wolfcamp Series. The Marathon Series are correlated with the rift radial Abitibi dykes (1140?Ma), and the Geordie-Wolfcamp Series with the rift parallel Pukaskwa and Copper Island dykes. U-Pb ages determined for five gabbros from the Layered and Marathon Series are between 1107•7 and 1106•0?Ma. Radiogenic isotope ratios show near chondritic (CHUR) ?Nd(1106?Ma) and 87Sr/86Sri values that range from -0•38 to +1•13 and 0•702537 to 0•703944, respectively. Distinctive geochemical properties of the Marathon Series and Abitibi dykes, such as Ba/La (14-37), Th/Nb (0•06-0•12), La/Sm (3•8-7•7), Sr/Nd (21-96) and Zr/Sm (9-19), are very different from those of the Geordie-Wolfcamp Series and a subset of Copper Island and Pukaskwa dykes with Ba/La (8•7-11), Th/Nb (0•12-0•13), La/Sm (6•7-7•9), Sr/Nd (5-7•8) and Zr/Sm (18-24). Each unit exhibits covariation between incompatible element ratios such as Zr/Sm and Nb/La or Gd/Yb, Sr/Nd and Ba/La, and Nb/Y and Zr/Y, which are consistent with mixing relationship between two or more mantle domains. These characteristics are unlike those of intrusions on the NW shoulder of the MCR, but resemble those of mafic rocks occurring in the East Kenya Rift. The results imply that an unusual and long-lived mantle source was present in the NE MCR for at least 34?Myr (spanning the 1140?Ma Abitibi dykes and the 1106?Ma Marathon series) and indicate potential for Cu-PGE mineralization in an area much larger than was previously recognized.
DS1988-0431
1988
Magnusson, S.G.Magnusson, S.G., Bjornsson, A.Directional spectral analysis and filtering of geophysical mapsGeophysics, Vol. 53, No. 12, December pp. 1587-1591GlobalGeophysics, Spectral Analysis-maps
DS1993-0955
1993
Magomedov, M.N.Magomedov, M.N.Reconstructing the thermal history of mineralsGeochemistry International, Vol. 30, No. 2, pp. 54-61RussiaGeochronology, Syngenetic minerals
DS202009-1624
2020
Magrez, A.Dorfman, S.M., Potapkin, V., Lv, M., Greenberg, E., Kupenko, I., Chumakov, A.I., Bi, W., Alp, E.E., Liu, J., Magrez, A., Dutton, S.E., Cava, R.J., McCammon, C.A., Gillet, P.Effects of composition and pressure on electronic states of iron in bridgmanite.American Mineralogist, Vol. 105, pp. 1030-1039. pdfMantleredox

Abstract: Electronic states of iron in the lower mantle's dominant mineral, (Mg,Fe,Al)(Fe,Al,Si)O3 bridgmanite, control physical properties of the mantle including density, elasticity, and electrical and thermal conductivity. However, the determination of electronic states of iron has been controversial, in part due to different interpretations of Mössbauer spectroscopy results used to identify spin state, valence state, and site occupancy of iron. We applied energy-domain Mössbauer spectroscopy to a set of four bridgmanite samples spanning a wide range of compositions: 10-50% Fe/total cations, 0-25% Al/total cations, 12-100% Fe3+/total Fe. Measurements performed in the diamond-anvil cell at pressures up to 76 GPa below and above the high to low spin transition in Fe3+ provide a Mössbauer reference library for bridgmanite and demonstrate the effects of pressure and composition on electronic states of iron. Results indicate that although the spin transition in Fe3+ in the bridgmanite B-site occurs as predicted, it does not strongly affect the observed quadrupole splitting of 1.4 mm/s, and only decreases center shift for this site to 0 mm/s at ~70 GPa. Thus center shift can easily distinguish Fe3+ from Fe2+ at high pressure, which exhibits two distinct Mössbauer sites with center shift ~1 mm/s and quadrupole splitting 2.4-3.1 and 3.9 mm/s at ~70 GPa. Correct quantification of Fe3+/total Fe in bridgmanite is required to constrain the effects of composition and redox states in experimental measurements of seismic properties of bridgmanite. In Fe-rich, mixed-valence bridgmanite at deep-mantle-relevant pressures, up to ~20% of the Fe may be a Fe2.5+ charge transfer component, which should enhance electrical and thermal conductivity in Fe-rich heterogeneities at the base of Earth's mantle.
DS1900-0030
1900
Maguire, D.Maguire, D.Precious Stones and Gem Materials of the Pacific Coast States and Territories of the United States.Mines AND MINERALS, Vol. 20, DECEMBER PP. 222-223; PP. 255-256.United States, California, Montana, Idaho, Oregon, Arizona, West Coast, Rocky MountainsGemstones
DS1900-0686
1908
Maguire, D.Maguire, D.Gems and Precious Stones of AmericaMineral Science., Vol. 58, SEPT. 3RD. PP. 188-189.United StatesGemstones
DS1991-1037
1991
Maguire, D.J.Maguire, D.J., Goodchild, M.F., Rhind, D.W.Geographic information systems: principles and applicationsJ.wiley Publ, 640p. 416p. 2 vols. set approx. $ 300.00 United StatesGlobalGeographic Information systems, Book-ad
DS1988-0432
1988
Maguire, P.K.H.Maguire, P.K.H., Shah, E.R., Pointing, A.J., Cooke, P.A.V., KhanThe seismicity of KenyaJournal of African Earth Sciences, Vol. 7, No. 7-8, pp. 915-924KenyaGeophysics
DS1989-0767
1989
Maguire, P.K.H.Khan, M.A., Maguire, P.K.H., et al.A crustal seismic refraction line along the axis of the S. Kenya riftJournal of African Earth Sciences, Vol. 8, No. 2/3/4, pp. 455-460KenyaTectonics, Rifting
DS1992-0009
1992
Maguire, P.K.H.Aftab Khan, M., Maguire, P.K.H., Swain, C.J.Geophysical models of the Kenya riftTectonophysics, Vol. 209, pp. 209-211. Extended abstractEast Africa, KenyaTectonics, Geophysics -gravity, seismics
DS200612-1571
2006
Maguire, P.K.H.Yirgu, G., Ebinger, C.J., Maguire, P.K.H.The Afar volcanic province within the East African Rift sytem.Geological Society of London, Special Publication, No. 259, 336p. $ 200.00Africa, East AfricaMantle plume, paleomagnetism
DS202006-0924
2020
Maguire, R.R.Jones, T.D., Maguire, R.R., van Keken, P.E., Ritsema, J., Koelemeijer, P.Subducted oceanic crust as the origin of seismically slow lower-mantle structures.Progress in Earth and Planetary Science , Vol. 7, 16p. PdfMantlegeophysics - seismics

Abstract: Mantle tomography reveals the existence of two large low-shear-velocity provinces (LLSVPs) at the base of the mantle. We examine here the hypothesis that they are piles of oceanic crust that have steadily accumulated and warmed over billions of years. We use existing global geodynamic models in which dense oceanic crust forms at divergent plate boundaries and subducts at convergent ones. The model suite covers the predicted density range for oceanic crust over lower mantle conditions. To meaningfully compare our geodynamic models to tomographic structures, we convert them into models of seismic wavespeed and explicitly account for the limited resolving power of tomography. Our results demonstrate that long-term recycling of dense oceanic crust naturally leads to the formation of thermochemical piles with seismic characteristics similar to the LLSVPs. The extent to which oceanic crust contributes to the LLSVPs depends upon its density in the lower mantle for which accurate data is lacking. We find that the LLSVPs are not composed solely of oceanic crust. Rather, they are basalt rich at their base (bottom 100-200 km) and grade into peridotite toward their sides and top with the strength of their seismic signature arising from the dominant role of temperature. We conclude that recycling of oceanic crust, if sufficiently dense, has a strong influence on the thermal and chemical evolution of Earth’s mantle.
DS200612-1485
2006
Magyati-Kope, B.Vitos, L., Magyati-Kope, B., Ahuja, R., Kollar, J., Grimvall, G., Johansson, B.Phase transformations between garnet and perovskite phases in the Earth's mantle: a theoretical study.Physics of the Earth and Planetary Interiors, Vol. 156, 1-2, pp. 108-116.MantleLower mantle, majorite, geophysics -seismic
DS1995-1143
1995
Mah, A.Mah, A., Taylor, G.R., Lennox, P., Balia, L.Lineament analyses of Land sat thematic mapper images, Northern TerritoryPhotogr. Eng. and Remote Sensing, Vol. LXI, No. 6, June pp. 761-773AustraliaRemote sensing, Structure - lineaments
DS200812-1082
2008
Mah, D.Smart, K.A., Heaman, L.M., Chocko, T., Simonetti, A., Kopylova, M., Mah, D., Daniels, D.The origin of diamond rich high MGO eclogite xenoliths from the Jericho kimberlite, Nunavut.Northwest Territories Geoscience Office, p. 56-57. abstractCanada, NunavutDeposit - Jericho
DS200912-0701
2009
Mah, D.Smart, K.A., Heaman, L.M., Chacko, T., Simonetti, A., Kopylova, M., Mah, D., Daniels, D.The origin of hig MgO diamond eclogites from the Jericho kimberlite, Canada.Earth and Planetary Science Letters, Vol. 284, 3-4, pp. 527-537.Canada, NunavutDeposit - Jericho
DS201509-0415
2015
Mahaaj, S.M.Magee, C., Mahaaj, S.M., Wrona, T., Jackson, A-L.Controls on the expression of igneous intrusions in seismic reflection data.Geosphere, Vol. 11, 4, pp. 1024-1041.MantleMagmatism

Abstract: The architecture of subsurface magma plumbing systems influences a variety of igneous processes, including the physiochemical evolution of magma and extrusion sites. Seismic reflection data provides a unique opportunity to image and analyze these subvolcanic systems in three dimensions and has arguably revolutionized our understanding of magma emplacement. In particular, the observation of (1) interconnected sills, (2) transgressive sill limbs, and (3) magma flow indicators in seismic data suggest that sill complexes can facilitate significant lateral (tens to hundreds of kilometers) and vertical (<5 km) magma transport. However, it is often difficult to determine the validity of seismic interpretations of igneous features because they are rarely drilled, and our ability to compare seismically imaged features to potential field analogues is hampered by the limited resolution of seismic data. Here we use field observations to constrain a series of novel seismic forward models that examine how different sill morphologies may be expressed in seismic data. By varying the geologic architecture (e.g., host-rock lithology and intrusion thickness) and seismic properties (e.g., frequency), the models demonstrate that seismic amplitude variations and reflection configurations can be used to constrain intrusion geometry. However, our results also highlight that stratigraphic reflections can interfere with reflections generated at the intrusive contacts, and may thus produce seismic artifacts that could be misinterpreted as real features. This study emphasizes the value of seismic data to understanding magmatic systems and demonstrates the role that synthetic seismic forward modeling can play in bridging the gap between seismic data and field observations.
DS2003-0760
2003
Mahabaleswar, B.Kumar, S.B.H., Jayananda, M., Kano, T., Swamy, N.S., Mahabaleswar, B.Late Archean juvenile magmatic accretion process in the eastern Dharwar Craton:Geological Society of India Memoir, No. 50, pp. 375-408.IndiaMagmatism
DS200412-1069
2003
Mahabaleswar, B.Kumar, S.B.H., Jayananda, M., Kano, T., Swamy, N.S., Mahabaleswar, B.Late Archean juvenile magmatic accretion process in the eastern Dharwar Craton: Kuppam Karimangalam area.Geological Society of India Memoir, No. 50, pp. 375-408.IndiaMagmatism
DS201012-0463
2010
Mahadevan, L.Mahadevan, L., Bendick, R., Liang, H.Why subduction zones are curved.Tectonics, Vol. 29, 6, TC6002MantleSubduction
DS1970-0236
1971
Mahadevan, T.M.Balasundaram, M.S., Mahadevan, T.M.Geological Environment of Diamond Deposits and its Bearing On Prospecting and Exploration in India.India Geological Survey Miscellaneous Publishing, No. 19, PP. 7-18.IndiaDiamond Genesis
DS1995-1144
1995
Mahadevan, T.M.Mahadevan, T.M.Deep continental structure of India: a reviewGeological Society India, 569pIndiaTectonics, Book -ad
DS2003-0859
2003
Mahadevan, T.M.Mahadevan, T.M.Lamprophyric rocks and Group II kimberlites ( in the Gondwana coalfields DamodarIn: Geology Of Bhiar & Jharkhand, Geological Society Of India, 563p., pp. 470-490.IndiaLamprophyres, Orangeites
DS200412-1198
2003
Mahadevan, T.M.Mahadevan, T.M.Lamprophyric rocks and Group II kimberlites ( in the Gondwana coalfields Damodar Valley).IN: Geology of Bhiar & Jharkhand, Geological Society of India, 563p., pp. 470-490.IndiaLamprophyre Orangeites
DS200812-0700
2008
Mahadevan, T.M.Mahadevan, T.M.Precambrian geological and structural features of the Indian Peninsula.Journal of the Geological Society of India, Vol. 72, 1, pp. 35-56.IndiaRegional geology
DS201810-2351
2018
Mahan, B.Mahan, B., Siebert, J., Blanchard, I., Moynier, F.Investigating Earth's formation history through copper & sulfur metal silicate partitioning during core-mantle differentiation.Journal of Geophysical Research: Solid Earth, doi:10.1029/2018JB015991Mantlecore mantle boundary

Abstract: Experiments wherein molten metal and silicate (rock?building) phases un?mix themselves due to their physical properties, i.e. metal?silicate partitioning, can be conducted at the high temperatures and pressures (HP?HT) that characterized Earth's differentiation into a core and mantle. The redistribution of elements between the metal and silicate phases ? their partitioning ? during this process can be measured and mathematically described, then placed into numerical models to better understand Earth's formation history. Here, we have mathematically characterized the HP?HT partitioning of copper, combined this with results for sulfur from literature, and input these characterizations into numerical models that track their distribution between Earth's core and mantle as it grows to its present mass. Copper and sulfur were chosen because they display different sensitivities to the physical mechanisms that govern planetary formation, and we can leverage this to better understand Earth's formation and differentiation history. Our results indicate that ~75% of Earth's precursor materials grew incrementally from relatively small bits of material ? on average ~0.1% of Earth's mass or less ? that is most compositionally similar to meteorite classes that are made up of iron?rich metal and silicate solids (chondrules) that are depleted in easily vaporized (volatile) elements, especially sulfur.
DS202104-0585
2021
Mahan, B.Kubik, E., Siebert, J., Blanchard, I., Agranier, A., Mahan, B., Moynier, F.Earth's volatile accretion as told by Cd, Bi, Sb and Ti core-mantle distribution.Geochimica et Cosmochimica Acta, in press available, 35p. PdfMantlegeodynamics
DS200512-1181
2005
Mahan, K.Williams, M.L., Jercinovic, M.J., Mahan, K., Drumond, G., Flowers, R.M., Davis, W.J.Regional high T metamorphic events in Proterozoic crust of Laurentia: implications of magmatic underplating for regional tectonics crustal evolution.GAC Annual Meeting Halifax May 15-19, Abstract 1p.Canada, Nunavut, Saskatchewan, AlbertaTectonics, Churchill Province
DS201112-0090
2011
Mahan, K.Blackburn, T., Bowring, S., Perron, T., Mahan, K., Dudas, F.A long term record of continental lithosphere exhumation via U-Pb thermochronology of the lower crust.Goldschmidt Conference 2011, abstract p.532.United States, MontanaCraton, keels
DS201112-0091
2011
Mahan, K.Blackburn, T., Bowring, S.A., Schoene, B., Mahan, K., Dudas, F.U-Pb thermochronology: creating a temporal record of lithosphere thermal evolution.Contributions to Mineralogy and Petrology, in press, availableMantleGeothermometry - xenoliths
DS201707-1362
2017
Mahan, K.Schulte-Pelkum, V., Mahan, K., Shen, W., Stachnik, J.The distribution and composition of high velocity lower crust across the continental US: comparison of seismic and xenolith dat a and implications for lithospheric dynamics and history.Tectonics, in press availableUnited Statesgeophysics

Abstract: The magnetotelluric component of the EarthScope USArray program has covered over 35% of the continental United States. Resistivity tomography models derived from these data image lithospheric structure and provide constraints on the distribution of fluids and melt within the lithosphere. We present a three-dimensional resistivity model of the northwestern United States which provides new insight into the tectonic assembly of western North America from the Archean to present. Comparison with seismic tomography models reveals regions of correlated and anti-correlated resistivity and velocity that help identify thermal and compositional variations within the lithosphere. Recent (Neogene) tectonic features reflected in the model include the subducting Juan de Fuca–Gorda plate which can be traced beneath the forearc to more than 100 km depth, high lithospheric conductivity along the Snake River Plain, and pronounced lower-crustal and upper-mantle conductivity beneath the Basin and Range. The latter is abruptly terminated to the northwest by the Klamath–Blue Mountains Lineament, which we interpret as an important structure during and since the Mesozoic assembly of the region. This boundary is interpreted to separate hot extended lithosphere from colder, less extended lithosphere. The western edge of Proterozoic North America, as indicated by the Cretaceous initial 87Sr/86Sr = 0.706 contour, is clearly reflected in the resistivity model. We further image an Archean crustal block (“Pend Oreille block”) straddling the Washington/Idaho border, which we speculate separated from the Archean Medicine Hat block in the Proterozoic. Finally, in the modern Cascades forearc, the geometry and internal structure of the Eocene Siletz terrane is reflected in the resistivity model. The apparent eastern edge of the Siletz terrane under the Cascades arc suggests that pre-Tertiary rocks fill the Washington and Oregon back-arc.
DS2003-0860
2003
Mahan, K.H.Mahan, K.H., Hoffman-Setka, D., Williams, M.L., Kopf, C.F.Contrasting lithotectonic domain boundaries within a deep crustal exposure, northernGeological Association of Canada Annual Meeting, Abstract onlySaskatchewanTectonics
DS200412-1199
2003
Mahan, K.H.Mahan, K.H., Hoffman-Setka, D., Williams, M.L., Kopf, C.F.Contrasting lithotectonic domain boundaries within a deep crustal exposure, northern Saskatchewan, western Canadian shield.Geological Association of Canada Annual Meeting, Abstract onlyCanada, SaskatchewanTectonics
DS200512-0675
2005
Mahan, K.H.Mahan, K.H., Williams, M.L.Reconstruction of a large deep crustal terrane: implications for the Snowbird tectonic zone and early growth of Laurentia.Geology, Vol. 33, 5, May pp. 385-388.Canada, Ontario, ManitobaTectonics, mantle
DS200512-0676
2005
Mahan, K.H.Mahan, K.H., Williams, M.L., Dumond, G., Card, C.Reconstruction of a large deep crustal terrane: implications for the Snowbird tectonic zone and early growth of Laurentia.GAC Annual Meeting Halifax May 15-19, Abstract 1p.Canada, Alberta, SaskatchewanTrans Hudson Orogen, tectonics
DS200612-0400
2006
Mahan, K.H.Flowers, R.M., Mahan, K.H., Bowring, S.A., Williams, M.L., Pringle, M.S., Hodges, K.V.Multistage exhumation and juxaposition of lower continental crust in the western Canadian Shield: linking high resolution U Pb and 40 Ar / 39 Ar thermochronometry with pressure temperature deformation paths.Tectonics, Vol. 25, 4, TC4003, 20p.Canada, Alberta, Saskatchewan, Northwest TerritoriesGeothermometry, thermocrhonmetry, deformation P T
DS200812-0357
2008
Mahan, K.H.Flowers, R.M., Bowring, S.A., Mahan, K.H., Williams, M.L., Wiliams, I.S.Stabilization and reactivation of cratonic lithosphere from the lower crustal record in the western Canadian Shield.Contributions to Mineralogy and Petrology, in press available, 21p.Canada, SaskatchewanCraton
DS200812-0358
2008
Mahan, K.H.Flowers, R.M., Bowring, S.A., Mahan, K.H., Williams, M.L., Williams, I.S.Stabilization and reactivation of cratonic lithosphere from the lower crustal record in the western Canadian Shield.Contributions to Mineralogy and Petrology, Vol. 156, 4, pp. 529-549.Canada, Northwest TerritoriesCraton
DS200812-0359
2008
Mahan, K.H.Flowers, R.M., Bowring, S.A., Mahan, K.H., Williams, M.L., Williams, I.S.Stabilization and reactivation of cratonic lithosphere from the lower crustal record in the western Canadian shield.Contributions to Mineralogy and Petrology, in press available, 21p.Canada, Alberta, Saskatchewan, ManitobaGeochronology, recycling
DS1991-1591
1991
Mahan, S.Sims, P.K., Peterman, Z.E., Hildenbrand, T.G., Mahan, S.Precambrian basement map of the Trans-Hudson Orogen and adjacent northern Great Plains, United States (US)United States Geological Survey (USGS), Map I 2214, 1: 1, 000, 000 $ 3.10Minnesota, Montana, Nebraska, WyomingPrecambrian, Map
DS2002-0411
2002
Mahanta, A.M.Dyke, A.L., Harmon, P., Mahanta, A.M.Falcon spreads its wings. Einstein and Newton... now new ones Galileo .. brief summary of performance and rationale behind BHP Billiton business.Preview, August pp. 25-28.Australia, Canada, United States, Mexico, Chile, Peru, South AfricaGeophysics - magnetics, Kimberlites
DS2003-0861
2003
Mahatha, S.Mahatha, S., Dutta, P.Incorporating cumulative impact concerns into EIAsMining Environmental Management, Vol. 11, 2, March pp. 16-21.GlobalCheck list, Environmental - example coal project
DS200412-1200
2003
Mahatha, S.Mahatha, S., Dutta, P.Incorporating cumulative impact concerns into EIAs.Mining Environmental Management, Vol. 11, 2, March pp. 16-21.GlobalCheck list Environmental - example coal project
DS2002-0983
2002
Mahavan, V.Mahavan, V.Kimberlite occurrences in Raichurara, KarnatakaJournal of the Geological Society of India, Vol. 60, 4, Oct., pp.478-9.IndiaBlank
DS200412-1201
2002
Mahavan, V.Mahavan, V.Kimberlite occurrences in Raichurara, Karnataka.Journal of the Geological Society of India, Vol. 60, 4, Oct., pp.478-9.IndiaKimberlite
DS200712-0667
2007
Mahbubui Ameen, S.M.Mahbubui Ameen, S.M., Wilde, S.A., Kabir, Z., Akon, E., Chowdbury, K.R., Khan, S.H.Paleoproterozoic granitoids in the basement of Bangladesh: a piece of the Indian Shield or an exotic fragment of the Gondwana jigsaw?Gondwana Research, Vol. 12, 4, pp. 380-387.IndiaIndian Shield
DS200812-0534
2008
Mahdjoub, Y.Kahoui, M., Mahdjoub, Y., Kaminsky, F.V.Possible primary sources of diamond in the North African Diamondiferous province.Geological Society of London, Ennih and Ligeois eds. The Boundaries of the West African Craton., Special Publication SP297, pp. 77-108.Africa, AlgeriaDiamond genesis
DS201201-0851
2011
Mahdjoub, Y.Kahoui, M., Kemainsky, F.V., Griffin, W.L., Belousova, E., Mahdjoub, Y., Chabane, M.Detrital pyrope garnets from the El Kseibat area, Algeria: a glimpse into the lithospheric mantle beneath the north-eastern edge of the West African Craton.Journal of African Earth Sciences, In press available, 46p.Africa, AlgeriaGeochemistry - El Kseibat
DS201212-0346
2012
Mahdjoub, Y.Kahoui, M., Kaminsky, F.V., Griffin, W.L., Belousova, E., Mahdjoub, Y., Chabane, M.Detrital pyrope garnets from the El Kseibat area, Algeria: a glimpse into lithospheric mantle beneath the north eastern edge of the west African Craton.Journal of African Earth Sciences, Vol. 63, Feb. pp. 1-11.AfricaEglab shield
DS201312-0454
2012
Mahdjoub, Y.Kaminsky, F.V., Kahoui, M.,Mahdjoub, Y., Belousova, E., Griffin, W.L.,O'Reilly, S.Y.Pyrope garnets from the Eglab Shield, Algeria: look inside the Earth's mantle in the West African Craton and suggestions about primary sources of diamond and indicator minerals.Vladykin, N.V. ed. Deep seated magmatism, its sources and plumes, Russian Academy of Sciences, pp. 73-103.Africa, AlgeriaMineralogy
DS1975-1202
1979
Maher, A.T.Robins, B. , Maher, A.T.Geology and Geochemistry of a Metamorphosed Picrite Ankaramite Dyke Suite from the Seiland Province, Northern Norway.Norske Geol. Tidsskr., Vol. 59, No. 1, PP. 67-9.Norway, ScandinaviaBlank
DS1990-0526
1990
Maher, M.J.Geerthsen, K., Maher, M.J.Gravity signature of an Archean craton/Proterozoic mobile belt transition in southern AfricaSociety of Exploration Geophysicists, 60th. Annual Meeting held, San, Vol. 1, pp. 613-616. Extended abstractSouth AfricaGeophysics -gravity, Craton
DS1983-0429
1983
Maher, P.Maher, P.Diamond Search Loses SparkleMining And Oil Review., JULY 21ST.AustraliaProspecting, Investment, Ashton Joint Venture
DS1984-0471
1984
Maher, P.Maher, P., Wood, E., Louthean, R.Argyle Production Makes Its First World ImpressionRegister of Australian Mining, 1983-1984, PP. 41-48.Australia, Western Australia, Argyle, New South WalesCurrent Activities, Markets, Cso, Prospecting, Politics, Investment
DS1994-0480
1994
Maher, S.G.Eby, G.N., Maher, S.G., Poland, L.J.Petrology and geochemistry of the Beemerville nepheline syenite complex, northern New Jersey, USAGeological Association of Canada (GAC) Abstract Volume, Vol. 19, p. posterGlobalAlkaline rocks, Beemerville
DS2002-0984
2002
Maheshwari, A.Maheshwari, A., Sial, A.N., Chittora, V.K., Bhu, H.A positive d13C carb anomaly in Paleoproterozoic carbonates of the Aravalli Craton, western India: support for a global isotopic excursion.Journal of Asian Earth Sciences, Vol. 21, 1, pp. 59-67.IndiaGeochronology
DS1995-1145
1995
Mahfoud, R.F.Mahfoud, R.F., Beck, J.N.Composition, origin and classification of extrusive carbonatites in rift edSouthern Syria.International Geology Review, Vol. 37, No. 4, April pp. 361-?SyriaCarbonatite, Tectonics
DS2002-0985
2002
Mahfoud, R.F.Mahfoud, R.F.Presence of diamond in the pyrope peridotite, Dreikeesh area, Tartous province, NW Syria: a new theory on the origin of diamond.Microchemical Journal, Vol. 73, 3, pp. 265-71. Ingenta 1024565221SyriaDiamond - genesis
DS1986-0566
1986
Mahin, R.A.Meyer, H.O.A., Mahin, R.A.The kimberlites of Guinea, West AfricaProceedings of the Fourth International Kimberlite Conference, Held Perth, Australia, No. 16, pp. 66-68GuineaPetrology, Analyses
DS201709-1982
2017
Mahlaku, S.M.Elburg, M.A., Andersen, T., Mahlaku, S.M., Cawthorn, R.G., Kramers, J.A potassic magma series in the Pilanesberg alkaline complex.Goldschmidt Conference, abstract 1p.Africa, South Africaalkaline rocks

Abstract: The Pilanesberg Alkaline Complex (South Africa) consists of a partially eroded phonolitic-trachytic package of lavas and tuffs, intruded by consanguinous syenites and nepheline syenites (foyaites). The latter have been divided in several units, based on their colour and mineralogy. Most of the foyaitic units are sodic in composition, but whole rock analyses show that some samples are more potassic, with Na2O/K2O<0.8. This observation, together with old reports of leucite-bearing lavas [1], could suggest the existence of a second, potassic magmatic lineage. To investigate whether the observed potassium-enrichment is a primary feature, or the result of deuteric alteration, the mineralogical distinction between sodic and potassic samples was investigated. The mineralogy of the sodic samples is dominated by nepheline, alkali-feldspar and aegirine, ± titanite, amphibole, biotite, and late agpaitic phases [2]. Within the potassic samples, the main primary ferromagnesian mineral is biotite, which shows conspicuous zoning in thin section; nepheline has been extensively replaced by sodalite and cancrinite, but alkali-feldspar appears relatively unaltered. No agpaitic minerals were observed. U-Pb isotope systematics of titanite are similar for sodic and potassic samples in terms of the age (ca. 1.4 Ga) and composion of common Pb; Ar-Ar dating of biotite also gives ca. 1.4 Ga, showing that biotite is a primary magmatic phase. Compositions of the biotite in sodic and potassic samples are similar, with the sodic samples having slightly higher Fe# (independent of whole rock Fe#), higher Na, but lower (Na+K) and Ba. Zoning in biotite from potassic samples is related to a decrease in Mg, Ti and F in the rim of the crystals. Despite the primary character of the biotite, the question whether the potassic samples reflect a combination of alteration and perhaps minor crustal contamination, or a separate mag
DS201709-2028
2016
Mahlangau, T.Mahlangau, T., Moemise, N., Ramakokovhu, M.M., Olubambi, P.A., Shongwe, M.B.Separation of kimberlite from waste rocks using sensor based sorting at Culli nan diamond mine.South African Institute of Mining and Metallurgy, Vol. 116, 4, pp. 343-350.Africa, South Africadeposit - Cullinan

Abstract: Near-infrared (NIR) spectroscopy sorting technology is incorporated in an automated optical mineral sorter that can discriminate between materials using the differences in characteristics when exposed to near-infrared radiation. During September 2014 to April 2015, a pilot plant that utilized NIR technology to discriminate between kimberlite and waste materials was commissioned to determine the viability of including this technology in the diamond winning process flow sheet at Cullinan Diamond Mine. The plant was used to minimize the waste content in the size fraction -70+35 mm that reports to the crushing section and then to the dense media separation process. This paper describes the initial test work, conducted at Mintek, that led to the decision to conduct a pilot-scale study. The mineralogical characterization of the feed and product streams to establish the sorting criteria and the operational data obtained during the pilot plant campaign are described. The results indicated a good possibility of discriminating between the kimberlite and waste material using NIR technology. However, the consistency of discrimination was not good enough to avoid the risk of potential diamond loss. Furthermore, a lower than expected availability of the machine reduced the throughput capabilities.
DS201612-2319
2016
Mahlangu, T.Mahlangu, T., Moemise, N., Ramakokovhu, M.M., Olubambi, P.A., Shongwe, M.B.Seperation of kimberlite from waste rocks using sensor-based sorting at Culli nan diamond mine.Journal of South African Institute of Mining and Metallurgy, Vol. 116, Apr. pp. 343-348.Africa, South AfricaDeposit - Cullinan

Abstract: Near-infrared (NIR) spectroscopy sorting technology is incorporated in an automated optical mineral sorter that can discriminate between materials using the differences in characteristics when exposed to near-infrared radiation. During September 2014 to April 2015, a pilot plant that utilized NIR technology to discriminate between kimberlite and waste materials was commissioned to determine the viability of including this technology in the diamond winning process flow sheet at Cullinan Diamond Mine. The plant was used to minimize the waste content in the size fraction -70+35 mm that reports to the crushing section and then to the dense media separation process. This paper describes the initial test work, conducted at Mintek, that led to the decision to conduct a pilot-scale study. The mineralogical characterization of the feed and product streams to establish the sorting criteria and the operational data obtained during the pilot plant campaign are described. The results indicated a good possibility of discriminating between the kimberlite and waste material using NIR technology. However, the consistency of discrimination was not good enough to avoid the risk of potential diamond loss. Furthermore, a lower than expected availability of the machine reduced the throughput capabilities.
DS1992-1096
1992
Mahlburg Kay, S.Mpodozis, C., Mahlburg Kay, S.Late Paleozoic to Triassic evolution of the Gondwana margin: evidence from Chilean frontal Cordilleran batholithsGeological Society of America (GSA) Bulletin, Vol. 104, No. 8, August pp. 999-1014Andes, ChileTectonics, Cordilleran batholiths
DS1992-1575
1992
Mahlburg Kay, S.Turcotte, D.L., Mahlburg Kay, S.On the coupling between plate tectonics and mantle convectionEos Transactions, Vol. 73, No. 14, April 7, supplement abstracts p. 272MantleMantle convection, Tectonics
DS1993-0956
1993
Mahlburg Kay, S.Mahlburg Kay, S., Ramos, V.A., Marquez, M.Evidence in Cerro Pampa volcanic rocks for slab melting prior to Ridge-Trench collision in southern South AmericaJournal of Geology, Vol. 101, No. 6, November pp. 703-714Argentina, PatagoniaAdakite flows, Magmatic, melt
DS1996-0873
1996
Mahlburg Kay, S.Mahlburg Kay, S., Orrell, S., Abbruzzi, J.M.Zircon and whole rock neodymium lead isotopic evidence for a Grenville age and a Laurentian Origin for the basementJournal of Geology, Vol. 104, No. 6, Nov. pp. 637-648ArgentinaGeochronology, Precordillera
DS2002-0986
2002
Mahlburg Kay, S.Mahlburg Kay, S., Mpodozis, C.Magmatism as a probe to the Neogene shallowing of the Nazca plate beneath the modern Chilean flat slab.Journal of South American Earth Sciences, Vol.15,1,Apr.pp.39-57.Chile, AndesSubduction, Magmatism
DS200812-0550
2008
Mahlburg Kay, S.Kay, R.W., Mahlburg Kay, S.The Armstrong Unit ( AU=km3/yr) and processes of crust mantle mass flux.Goldschmidt Conference 2008, Abstract p.A455.TechnologyMagmatism, subduction
DS1991-0833
1991
Mahlburg-Kay, S.Kay, R.W., Mahlburg-Kay, S.Creation and destruction of lower continental crustGeologische Rundschau, Vol. 80, No. 2, pp. 259-278GlobalMantle, crust, Geochemistry, bulk composition
DS200912-0421
2009
Mahlen, N.Kylander Clar, A.R.C., Hacker, B.R., Johnson, C.M., Beard, B.L., Mahlen, N.Slow subduction of a thick ultrahigh pressure terrane.Tectonics, Vol. 28, 2, TC2003MantleUHP
DS1998-0918
1998
Mahmood, A.Mahmood, A., Crawford, J.P., Michaud, R., Jezek, K.C.Mapping the world with remote sensingEos, Vol. 79, No. 2, Jan. 13, p. 17, 23.GlobalRemote Sensing, Radarsat
DS1960-0572
1965
Mahmood, F.Mahmood, F.Golconda Diamond MinesGeografia., Vol. 4, No. 1-2, PP. 29-46.India, Andhra PradeshDiamond Occurrences, History
DS201112-0631
2010
Mahon, K.A.Mahon, K.A.Estudos com base em quimica semi-quantitativa atraves da microscopis eletronica de Varredura dos minerais satelites do corpo kimberlitico no minicipio de Ariquemes5th Brasilian Symposium on Diamond Geology, Nov. 6-12, abstract p. 65.South America, Brazil, RondoniaGeochemistry - Ariquemes
DS1996-0874
1996
Mahon, K.I.Mahon, K.I.The "New York" regression: application of an improved statistical method togeochemistryInternational Geology Review, Vol. 38, pp. 293-303GlobalIsotope geochemistry, Standard errors
DS1975-0374
1976
Mahon, M.W.Page, R.W., Blake, D.H., Mahon, M.W.Geochronology and Related Aspects of Acid Volcanics Associated Granites, and Other Proterozoic Rocks of the Granites-tanami Region.B.m.r. Journal of Aust. Geol. Geophys., Vol. 1, PP. 1-13.AustraliaKimberlite, Regional Geology
DS1993-1342
1993
Mahoney, J.Rubin, K., Mahoney, J.What's on the plume channel?Nature, Vol. 362, m March 11, pp. 109-110GlobalHot spots, Mantle, Plumes
DS200612-1595
2006
Mahoney, J.Zhang, Z., Mahoney, J., Mao,J., Wang, F.Geochemistry of picritic and associated basalt flows of the western Emeishan flood basalt province, China.Journal of Petrology, Vol. 47, 10, pp. 1997-2019.ChinaPicrite
DS1987-0285
1987
Mahoney, J.J.He Xiong, D.A., Mahoney, J.J.Preliminary experimental study of the relationship between kimberlite and metasomatism of duniteEos, abstractGlobalMantle genesis
DS1995-1061
1995
Mahoney, J.J.Lassiter, J.C., De Paolo, D.J., Mahoney, J.J.Geochemistry of Wrangellia flood basalt province: implications for the roleof continental lithosphere.Journal of Petrology, Vol. 96, No. 4, pp. 983-1009United States, Wrangellia TerraneBasalt, Flood basalt genesis
DS1996-1417
1996
Mahoney, J.J.Tejada, M.L.G., Mahoney, J.J., Duncan, R.A., Hawkins, M.P.Age and geochemistry of basement and alkalic rocks of Malaita and SantaIsabel, Solomon Islands, Ontong JavaJournal of Petrology, Vol. 37, No. 2, pp. 361-394.GlobalGeochemistry, Alkaline rocks
DS1997-0717
1997
Mahoney, J.J.Mahoney, J.J., Coffin, M.F.Large igneous provinces - continental, oceanic and planetary floodvolcanism.American Geophysical Union (AGU) Geophys. Mon, No. 100, $ 65.00Idaho, Central African Republic, Colombia, South Africa, Russia, SiberiaBook - table of contents, Flood basalts, Mantle plumes
DS2001-0770
2001
Mahoney, J.J.Melluso, L., Morra, V., Brotzu, P., Mahoney, J.J.The Cretaceous igneous province of Madagascar: geochemistry and petrogenesis of lavas and dykes...Journal of Petrology, Vol. 42, No. 7, July, pp. 1249-78.Madagascar, central westernIgneous rocks - petrology
DS2003-1264
2003
Mahoney, J.J.Sheth, H.C., Mahoney, J.J., Baxter, A.N.Geochemistry of lavas from Mauritius, Indian Ocean: mantle sources and petrogenesisInternational Geology Review, Vol. 45, 9, pp. 780-797.MauritiusBasalts
DS200412-0883
2004
Mahoney, J.J.Ito, G., Mahoney, J.J.Hotspot and mid-ocean ridge basalt genesis from melting of a non-layered heterogeneous mantle.Geochimica et Cosmochimica Acta, 13th Goldschmidt Conference held Copenhagen Denmark, Vol. 68, 11 Supp. July, ABSTRACT p.A563.MantleConvection
DS200412-1803
2003
Mahoney, J.J.Sheth, H.C., Mahoney, J.J., Baxter, A.N.Geochemistry of lavas from Mauritius, Indian Ocean: mantle sources and petrogenesis.International Geology Review, Vol. 45, 9, pp. 780-797.Africa, MauritiusBasalts
DS200512-0465
2005
Mahoney, J.J.Ito, G., Mahoney, J.J.Flow and melting of a heterogeneous mantle: 1. method and importance to the geochemistry of ocean island and mid-ocean ridge basalts.Earth and Planetary Science Letters, Vol. 230, 1-2, pp. 29-46.MantleMagmatism, melting
DS200512-0466
2005
Mahoney, J.J.Ito, G., Mahoney, J.J.Flow and melting of a heterogeneous mantle. II.Earth and Planetary Science Letters, Vol. 230, 1-2, pp. 47-63.MantleMelting
DS200512-1249
2005
Mahoney, J.J.Zhang, S.Q., Mahoney, J.J., Mo, X.X., Ghazi, A.M., Milani, L., Crawford, A.J., Guo, T.Y., Zhao, Z.D.Evidence for a Wide spread Tethyan upper mantle with Indian - Ocean type isotopic characteristics.Journal of Petrology, Vol. 46, 4, pp. 829-858.Indian OceanGeochronology
DS201312-0082
2013
Mahoney, J.J.Bianco, T.A., Ito, G., van Hunen, J., Mahoney, J.J., Ballmer, M.D.Geochemical variations at ridge centered hotspots caused by variable melting of a veined mantle plume.Earth and Planetary Science Letters, Vol. 371-372, pp. 191-202.GlobalGeochemisty
DS2003-0862
2003
Mahoney, S.Mahoney, S., James, P., Mauger, A., Heinson, G.Geologic and regolith mapping for mineral exploration in the Gawler Craton of SouthInternational Geoscience and Remote Sensing Symposium, Vol. 3, pp. III 1779-81. Ingenta 1034976078AustraliaRemote sensing
DS200412-1202
2003
Mahoney, S.Mahoney, S., James, P., Mauger, A., Heinson, G.Geologic and regolith mapping for mineral exploration in the Gawler Craton of South Australia using Hyperion and other remote seInternational Geoscience and Remote Sensing Symposium, Vol. 3, pp. III 1779-81. Ingenta 1034976078AustraliaRemote sensing
DS200612-0752
2006
Mahotkin, I.Kurszlaukis, S., Mahotkin,I., Rotman, A.Y.,Kolesnikov, G.V., Makovchuk, I.V.Syn and post eruptive volcanic processes in the Yubileinaya kimberlite pipe, Yakutia,Emplacement Workshop held September, 5p. extended abstractRussia, YakutiaDeposit - Yubileinya , petrology
DS200912-0417
2009
Mahotkin, I.Kurszlaukis, S., Mahotkin, I., Rotman, A.Y., Kolesnikov, G.W., Makovchuk, I.V.Syn and post eruptive volcanic processes in the Yubileinaya kimberlite pipe, Yakutia, Russia and implications for the emplacement of South African style kimberliteLithos, In press available, 36p.Russia, YakutiaDeposit - Yubileinaya
DS200812-0296
2007
Mahotkin, I.I.Downes, H., Mahotkin, I.I., Beard, A.D., Hegner, E.Petrogenesis of alkali silicate, carbonatitic and kimberlitic magmas of the Kola alkaline carbonatite province.Vladykin Volume 2007, pp. 45-56.Russia, Kola PeninsulaCarbonatite
DS1995-1146
1995
Mahotkin, I.L.Mahotkin, I.L., Stolz, J., Zhuralev, D.Z.Mantle sources of low Ti lamproites from the Mesozoic collision zone of the Aldan shield, East Siberia.Proceedings of the Sixth International Kimberlite Conference Abstracts, pp. 339-341.Russia, Siberia, Aldan ShieldLamproite, Deposit -Yakokut, Inagli, Yakodka, Zvezdochka, Mrachnay
DS1995-1147
1995
Mahotkin, I.L.Mahotkin, I.L., Sublukov, S.M., Zhuralev, D.Z., ZherdevGeochemistry and Strontium, neodymium composition of kimberlites, melilitites, and basalts from Arkangelsk region.Proceedings of the Sixth International Kimberlite Conference Abstracts, pp. 342-344.Russia, ArkangelskGeochemistry, Deposit -Winter Cost, Nenoksa, Chidvia, Verhotinskoiy
DS1998-0919
1998
Mahotkin, I.L.Mahotkin, I.L.Petrology of Group 2 kimberlite olivine lamproite K@L series from the Kostomuksha area, Karelia, northwest Russia.7th International Kimberlite Conference Abstract, pp. 529-31.Russia, KareliaLamproites, Deposit - Kostomuksha
DS1998-0920
1998
Mahotkin, I.L.Mahotkin, I.L., Skinner, E.M.M.Kimberlites from the Archangelsk region - a rock type transitional betweenkimberlites, melnoites, lamproites7th International Kimberlite Conference Abstract, pp. 532-34.Russia, Arkangelsk, Kola PeninsulaClassification - Group I, II, Petrology
DS1999-0675
1999
Mahotkin, I.L.Skinner, E.M.W., Mahotkin, I.L., Grutter, H.S.Melilite in kimberlites7th International Kimberlite Conference Nixon, Vol. 2, pp. 788-94.South Africa, Lesotho, RussiaPetrology - melilite, Deposit - Finsch, Voorspoed, Lace, Swartruggen
DS2001-0719
2001
Mahotkin, I.L.Mahotkin, I.L., Podkuiko, Y.A., Zhuravlev, D.Z.Early Paleozoic kimberlite melnoite magmatism of the Pri-Polar Urals and thAlkaline Magmatism -problems mantle source, pp. 151-60.GlobalMelnoite, Tectonics
DS2003-0313
2003
Mahotkin, I.L.Davies, G.R., Stolz, A.J., Mahotkin, I.L., Nowell, G.M., Pearson, D.G.Trace element and Sr Pb Nd Hf isotope evidence for ancient fluid related enrichment in8 Ikc Www.venuewest.com/8ikc/program.htm, Session 7, POSTER abstractRussia, Aldan ShieldGeochronology
DS2003-0863
2003
Mahotkin, I.L.Mahotkin, I.L., Downes, H., Hegner, E., Beard, A.D.Devonian dike swarms of alkaline, carbonatitic and primitiv magma type rocks from the8ikc, Www.venuewest.com/8ikc/program.htm, Session 4, POSTER abstractRussia, Kola PeninsulaMantle geochemistry
DS2003-0864
2003
Mahotkin, I.L.Mahotkin, I.L., Robey, J., Kurszlaukis, S., Valuev, E.P., Pylaev, N.F.Pipe emplacement model of the Lomonosov diamond deposit, Arkangelsk region, NW8 Ikc Www.venuewest.com/8ikc/program.htm, Session 1, AbstractRussiaGeology, economics, Deposit - Lomonosov
DS200412-0413
2003
Mahotkin, I.L.Davies, G.R., Stolz, A.J., Mahotkin, I.L., Nowell, G.M., Pearson, D.G.Trace element and Sr Pb Nd Hf isotope evidence for ancient fluid related enrichment in the source region of Aldan Shield lamproi8 IKC Program, Session 7, POSTER abstractRussia, Aldan ShieldKimberlite petrogenesis, geochronology
DS200412-1203
2003
Mahotkin, I.L.Mahotkin, I.L., Robey, J., Kurszlaukis, S., Valuev, E.P., Pylaev, N.F.Pipe emplacement model of the Lomonosov diamond deposit, Arkangelsk region, NW Russia.8 IKC Program, Session 1, AbstractRussiaGeology, economics Deposit - Lomonosov
DS200512-0677
2001
Mahotkin, I.L.Mahotkin, I.L., Podkuiko, Yu.A., Zhuravlev, D.Z.Early Paleozoic kimberlite melnoite magmatism of the Pre-Polar Urals and the geodynamic formation model.Alkaline Magmatism and the problems of mantle sources, pp. 151-160.Russia, UralsMelnoites
DS200612-0315
2006
Mahotkin, I.L.Davies, G.R., Stolz, A.J., Mahotkin, I.L., Nowell, G.M., Pearson, D.G.Trace element and Sr Pb Nd Hf isotope evidence for ancient fluid dominated enrichment of the source of the Aldan Shield, lamproites.Journal of Petrology, Vol. 47, 6, pp. 1119-1146.RussiaGeochronology, geochemistry lamproites
DS201608-1419
2016
Maia, M.Maia, M., Sichel, S., Briais, A., Brunelli, D., Ligi, M., Ferreira, N., Campos, T., Mougel, B., Brehme, I., Hemond, C., Motoki, A., Moura, D., Scalabrin, C., Pessanha, I., Alves, E., Ayres, A., Oliveira, P.Extreme mantle uplift and exhumation along a transpressive transform fault.Nature Geoscience, Vol. 9, 8, pp. 619-623.MantleRidges

Abstract: Mantle exhumation at slow-spreading ridges is favoured by extensional tectonics through low-angle detachment faults1, 2, 3, 4, and, along transforms, by transtension due to changes in ridge/transform geometry5, 6. Less common, exhumation by compressive stresses has been proposed for the large-offset transforms of the equatorial Atlantic7, 8. Here we show, using high-resolution bathymetry, seismic and gravity data, that the northern transform fault of the St Paul system has been controlled by compressive deformation since ~10?million years ago. The long-lived transpression resulted from ridge overlap due to the propagation of the northern Mid-Atlantic Ridge segment into the transform domain, which induced the migration and segmentation of the transform fault creating restraining stepovers. An anticlockwise change in plate motion at ~11?million years ago5 initially favoured extension in the left-stepping transform, triggering the formation of a transverse ridge, later uplifted through transpression, forming the St Peter and St Paul islets. Enhanced melt supply at the ridge axis due to the nearby Sierra Leone thermo chemical anomaly9 is responsible for the robust response of the northern Mid-Atlantic Ridge segment to the kinematic change. The long-lived process at the origin of the compressive stresses is directly linked to the nature of the underlying mantle and not to a change in the far-field stress regime.
DS2003-0865
2003
Maiade Hollanda, M.H.Maiade Hollanda, M.H., Pimentel, M.M., Jardim de Sa, E.F.Paleoproterozoic subduction related metasomatic signatures in the lithospheric mantleJournal of South American Earth Sciences, Vol. 15, 8, pp. 885-900.Brazil, southeastSubduction, Alkaline rocks
DS200412-1204
2003
Maiade Hollanda, M.H.Maiade Hollanda, M.H., Pimentel, M.M., Jardim de Sa, E.F.Paleoproterozoic subduction related metasomatic signatures in the lithospheric mantle beneath NE Brazil: inferences from trace eJournal of South American Earth Sciences, Vol. 15, 8,pp. 885-900.South America, BrazilSubduction Alkaline rocks
DS200812-0903
2008
Maicher, D.Podolsky, M.H., Seller, M.H., Kryvoshlyk, I.N., Seghedi, I., Maicher, D.Whole rock geochemistry investigations of the 5034 and Tuzo kimberlites and potential applications to improving geology and resource models, Gahcho Kue project, NWTNorthwest Territories Geoscience Office, p. 72. abstractCanada, Northwest TerritoriesDeposit - Gahcho Kue
DS200912-0682
2009
Maicher, D.Seghedi, I., Kurzlaukis, S., Maicher, D.Basaltic diatreme to root zone volcanic processes in Tuzo kimberlite pipe (Gahcho Kue kimberlite field, NWT, Canada).GAC/MAC/AGU Meeting held May 23-27 Toronto, Abstract onlyCanada, Northwest TerritoriesDeposit - Tuzo
DS200912-0683
2009
Maicher, D.Seghedi, I., Kurzlaukis, T., Ntaflos, S., Maicher, D.Mineralogy of digested wall rock xenoliths in transitional coherent kimberlites of Tuzo pipe, Gahcho Kue kimberlite field, NWT, Canada.Goldschmidt Conference 2009, p. A1190 Abstract.Canada, Northwest TerritoriesDeposit - Gacho Kue
DS200912-0684
2009
Maicher, D.Seghedi, I., Maicher, D., Kurslaukis, S.Volcanology of Tuzo pipe ( Gahcho Kue cluster) root diatreme processes re-interpreted.Lithos, In press available 37p.Canada, Northwest TerritoriesDeposit - Gahcho Kue
DS201312-0485
2013
Maichur, D.Kipl, A.F., Werner, R., Gohl, K., Van den Bogaard, P., Hoemle, K., Maichur, D., Klugel, A.Seamounts off the West Antarctic margin: a case for non-hotpsot driven intra-plate volcanism.Gondwana Research, Vol. 25, 4, pp. 1660-1679.AntarcticaIntra-plate volcanism
DS1990-0685
1990
Maiden, K.J.Henry, G., Clendenin, C.W., Stainstreet, I.G., Maiden, K.J.Multiple detachment model for the early rifting stAge of Late Proterozoic Damara orogen in NamibiaGeology, Vol. 18, No. 1, January pp. 67-71Southwest Africa, NamibiaTectonics, Damara orogen
DS1988-0433
1988
Maidens, J.M.Maidens, J.M., Paulson, K.V.A magnetotelluric investigation under the Williston Basin of southeasternSaskatchewan. Discussion. #2Canadian Journal of Earth Sciences, Vol. 25, No. 1, Janusry p; . 60-67SaskatchewanGeophysics
DS201212-0429
2012
Maier, A.C.Maier, A.C., Cates, N.L., Trail, D., Mojzsis, S.J.Geology, age and field relations of Hadean zircon bearing supracrustal rocks from Quad Creek, eastern Beartooth Mountains ( Montana and Wyoming) USA.Chemical Geology, Vol. 312-313, pp. 47-57.United States, MontanaWyoming Craton, geochronology
DS200712-0668
2007
Maier, R.Maier, R., Heinson, G., Thiel, S., Selway, K., Gill, R., Scroggs, M.A 3D lithospheric resistivity model of the Gawler Craton: southern Australia.Transactions of the Institution of Mining and Metallurgy, Vol. 116, 1, pp. 13-21.AustraliaGeophysics - resistivity
DS201012-0464
2009
Maier, W.Maier, W.Book review: Platinum, gold and diamonds: the adventures of Hans Merensky's discoveries by Machens, 308p. Schweizerbart Publ.Economic Geology, Vol. 104, 7, p. 1083.Africa, South AfricaBook review - history
DS1994-1088
1994
Maier, W.D.Maier, W.D., Eales, H.V.Plagioclase inclusions in orthopyroxene and olivine of the UG2 Merensky Reef interval: regional trends.South Africa Journal of Geology, Vol. 97, No. 4, pp. 408-414South AfricaInclusions -texture, Deposit -Bushveld Complex
DS2003-0866
2003
Maier, W.D.Maier, W.D., Roelofse, F., Barnes, S.J.The concentration of the Platinum Group elements in South African komatiites:Journal of Petrology, Vol. 44, 10, pp. 1787-1804.South AfricaMagmatism - not specific to diamonds
DS200412-1205
2003
Maier, W.D.Maier, W.D., Roelofse, F., Barnes, S.J.The concentration of the Platinum Group elements in South African komatiites: implications for mantle sources, melting regime anJournal of Petrology, Vol. 44, 10, pp. 1787-1804.Africa, South AfricaMagmatism - not specific to diamonds
DS200512-0678
2004
Maier, W.D.Maier, W.D., Barnes, S.J.Pt Pd and Pd Ir ratios in mantle derived magmas: a possible role for mantle metasomatism.South African Journal of Geology, Vol. 107, 3, pp. 333-340.MantleMetasomatism, platinum group elements
DS200612-0850
2005
Maier, W.D.Maier, W.D., Peltonen, P., Juvonen, R., Pienaar, C.Platinum group elements in peridotite xenoliths and kimberlite from the Premier kimberlite pipe, South Africa.South African Journal of Geology, Vol. 108, pp. 413-428.Africa, South AfricaDeposit - Premier, xenolith mineralogy
DS200712-0669
2007
Maier, W.D.Maier, W.D., McDonald, I., Peltonen, P., Barnes, S-J., Gurney, J., Hatton, C.Platinum group elements in mantle xenoliths from the Kaapvaal Craton.Plates, Plumes, and Paradigms, 1p. abstract p. A614.Africa, South Africa, Botswana, LesothoKimberley, Jagersfontein, Lethlakane, Finsch, Venetia
DS201212-0430
2012
Maier, W.D.Maier, W.D., Peltonen, P., McDonald, I., Barnes, S.J., Barnes, S-J., Hatton, C., Viljoen, F.The concentration of platinum group elements and gold in southern African and Karelian kimberlite hosted mantle xenoliths: implications for the noble metal content of the Earth's mantle.Chemical Geology, Vol. 302-303, pp. 119-135.Africa, southern AfricaKimberlite - PGM
DS201709-2029
2017
Maier, W.D.Maier, W.D., O'Brien, H., Peltonen, P., Barnes, S-J.Platinum group element contents of Karelian kimberlites: implications for the PGE budget of the sub-continental lithospheric mantle.Geochimica et Cosmochimica Acta, in press available, 14p.Europe, Finlanddeposit - Kaavi

Abstract: We present high-precision isotope dilution data for Os, Ir, Ru, Pt, Pd and Re in Group I and Group II kimberlites from the Karelian craton, as well as 2 samples of the Premier Group I kimberlite pipe from the Kaapvaal craton. The samples have, on average, 1.38 ppb Pt and 1.33 ppb Pd, with Pt/Pd around unity. These PGE levels are markedly lower, by as much as 80%, than those reported previously for kimberlites from South Africa, Brazil and India, but overlap with PGE results reported recently from Canadian kimberlites. Primitive-mantle-normalised chalcophile element patterns are relatively flat from Os to Pt, but Cu, Ni and, somewhat less so, Au are enriched relative to the PGE (e.g., Cu/Pd > 25.000). Pd/Ir ratios are 3,6 on average, lower than in most other mantle melts. The PGE systematics can be largely explained by two components, (i) harzburgite/lherzolite detritus of the SCLM with relatively high IPGE (Os-Ir-Ru)/PPGE (Rh-Pt-Pd) ratios, and (ii) a melt component that has high PPGE/IPGE ratios. By using the concentrations of iridium in the kimberlites as a proxy for the proportion of mantle detritus in the magma, we estimate that the analysed kimberlites contain 3–27% entrained and partially dissolved detritus from the sub-continental lithospheric mantle, consistent with previous estimates of kimberlites elsewhere (Tappe S. et al., 2016, Chem. Geol. http://dx.doi.org/10.1016/j.chemgeo.2016.08.019). The other major component in the samples is melt, modelled to contain an average of 0.85 ppb Pt and 1.09 ppb Pd. Assuming that Group II kimberlites are derived from relatively metasomatised SCLM, our data suggest that the metasomatised Karelian SCLM is relatively poor in Pt and Pd. If our data are representative of other Group II kimberlites elsewhere, this result could imply that the PGE enrichment in certain continental large igneous provinces, including Bushveld, is not derived from melting of metasomatised SCLM.
DS201710-2244
2017
Maier, W.D.Maier, W.D., O'Brien, H., Peltonen, P., Barnes, S-J.Platinum group element contents of Karelian kimberlites: implications for the PGE budget of the sub-continental lithospheric mantle.Geochimica et Cosmochimica Acta, Vol. 216, pp. 358-371.Europe, Finlanddeposit - Karelian

Abstract: We present high-precision isotope dilution data for Os, Ir, Ru, Pt, Pd and Re in Group I and Group II kimberlites from the Karelian craton, as well as 2 samples of the Premier Group I kimberlite pipe from the Kaapvaal craton. The samples have, on average, 1.38 ppb Pt and 1.33 ppb Pd, with Pt/Pd around unity. These PGE levels are markedly lower, by as much as 80%, than those reported previously for kimberlites from South Africa, Brazil and India, but overlap with PGE results reported recently from Canadian kimberlites. Primitive-mantle-normalised chalcophile element patterns are relatively flat from Os to Pt, but Cu, Ni and, somewhat less so, Au are enriched relative to the PGE (e.g., Cu/Pd > 25.000). Pd/Ir ratios are 3,6 on average, lower than in most other mantle melts. The PGE systematics can be largely explained by two components, (i) harzburgite/lherzolite detritus of the SCLM with relatively high IPGE (Os-Ir-Ru)/PPGE (Rh-Pt-Pd) ratios, and (ii) a melt component that has high PPGE/IPGE ratios. By using the concentrations of iridium in the kimberlites as a proxy for the proportion of mantle detritus in the magma, we estimate that the analysed kimberlites contain 3-27% entrained and partially dissolved detritus from the sub-continental lithospheric mantle, consistent with previous estimates of kimberlites elsewhere (Tappe S. et al., 2016, Chem. Geol. http://dx.doi.org/10.1016/j.chemgeo.2016.08.019). The other major component in the samples is melt, modelled to contain an average of 0.85 ppb Pt and 1.09 ppb Pd. Assuming that Group II kimberlites are derived from relatively metasomatised SCLM, our data suggest that the metasomatised Karelian SCLM is relatively poor in Pt and Pd. If our data are representative of other Group II kimberlites elsewhere, this result could imply that the PGE enrichment in certain continental large igneous provinces, including Bushveld, is not derived from melting of metasomatised SCLM.
DS201312-0613
2013
Maier, W-G.Mondal, S.K., Maier, W-G., Griffin, W.L.Ore deposits and the role of the lithospheric mantle.Lithos, One page introduction to forthcoming issue…. Does not appear to include diamonds.MantleMetasomatism
DS1990-1041
1990
Maier-Reimer, E.Mikolajewicz, U., Santer, B.D., Maier-Reimer, E.Ocean response to green house warmingNature, Vol. 345, June 14, pp. 589-593OceanGreenhouse, Climate
DS1996-1035
1996
Maijer, C.Nijland, T.G., Maijer, C., De Haas, G.J.L.M.The Skokkafjell troctolite: its bearing on the early P-T evolution of the Rogaland TerraneNeues Jahrb. fur Min, Vol. 171, No. 1, pp. 91-NorwayTroctolite
DS200412-1206
2004
Mail and GuardianMail and GuardianDe Beers in talks to return to the US.De Beers, Feb. 24, 1p.United StatesNews item - markets
DS200612-0851
2006
Maillard, A.Maillard, A., Malod, J., Thiebot, E., Klingelhoefer, F., Rehault, J-P.Imaging a lithospheric detachment at the continent ocean crustal transition off Morocco.Earth and Planetary Science Letters, Vol. 241, 3-4, Jan. 31, pp. 686-698.Africa, MoroccoGeophysics - seismics, exhumation
DS201212-0431
2012
Maimon, O.Maimon, O., Lyakhovsky, V., Melnik, O., Navon, O.The propagation of a dyke driven by gas saturated magma.Geophysical Journal International, Vol. 189, 2, pp. 956-966.MantleDykes
DS2003-1395
2003
Main, B.Tryggvason, B., Main, B.Impact of resolution of airborne gravity gradiometry for detection of kimberlite pipesPdac Abstract 2003, March 12, 1p.AustraliaTechnology - FalconTM
DS1992-1324
1992
Main, I.G.Sammonds, P.R., Meredith, P.G., Main, I.G.Role of pore fluids in the generation of seismic precursors to shearfractureNature, Vol. 359, No. 6392, September 17, p. 228-230GlobalCrust deformation, Geophysics -seismics
DS202205-0708
2022
Main, M.Moore, A.E., Cotterill, F.P.D., Main, M., Williams, H.B.The Zambesi: origins and legacies of Earth's oldest river system.Chapter , on requestAfrica, Angola, Zambia, Botswana, Zimbabwe, MozambiqueHistory

Abstract: The Zambezi rises with considerable modesty in north-west Zambia from a small spring on the gentle upland of the Southern Equatorial Divide - the watershed that separates the river from north-west-flowing tributaries of the Congo. The evolution of the Zambezi River has repeatedly modified the distribution of riverine plant and animal species. The hydrology of the Zambezi is further influenced by water exploitation by different users, along its main channel and tributaries. The dams have had severe ecological impacts on the major floodplains, as a result of the reduction of the supply of water and sediment. The major Early Cretaceous Zambezi-Limpopo River system entered the Mozambique coastal plain via a line of crustal weakness that was exploited by a major west-north-west trending dyke swarm. Drainage evolution of the Palaeo-Chambeshi system has been invoked as the primary cause of the recent evolution of the molerats.
DS2003-0867
2003
Mainkar, D.Mainkar, D., Lehmann, B., Haggerty, S.E.Discovery of the very large crater facies kimberlite system of Tokapal, Bastar District8ikc, Www.venuewest.com/8ikc/program.htm, Session 1 POSTER abstractIndiaKimberlite geology and economics, Deposit - Tokapal
DS200412-1207
2002
Mainkar, D.Mainkar, D.Notes: report on the international conference on diamond and gemstones held Feb. 9-15, 2002 in Raipur, Chhattisgarh.Journal Geological Society of India, Vol. 60, 3, pp. 343-344.IndiaConference note
DS200612-0237
2005
Mainkar, D.Chalapathi Rao, N.V., Burgess, R., Anand, M., Mainkar, D.Evidence for a Phanerozoic (478 Ma) Diamondiferous kimberlite emplacement epoch in the Indian Shield from 40 Ar/ 39Ar dating of the Kodomali kimberlite: implications ....Geological Society of India, Bangalore November Meeting Group Discussion on Kimberlites and Related Rocks India, Abstract p. 103-106.India, Bastar Craton, RodiniaTectonics - Kodomali, Pan African , Geothermometry
DS200612-0790
2006
Mainkar, D.Lehmann, B., Mainkar, D., Belyatsky, B.The Tokapal Crater facies kimberlite system, Chhattisgarh, India: reconnaissance petrography and geochemistry.Journal of the Geological Society of India, Vol. 68, 1, pp. 9-18.IndiaDeposit - Tokopal
DS200812-0701
2008
Mainkar, D.Mainkar, D., Lehmann, B., Burgess, R., Belyatsky, B.The Diamondiferous Behradih kimberlite pipe, Raipur district, Chhattisgarh, India.9IKC.com, 3p. extended abstractIndiaBastar Craton, Mainpur field
DS200912-0023
2009
Mainkar, D.Babu, E.V.S.S.K, Bhaskar Rao, Y.J., Mainkar, D., Pashine, J.K., Sirikant Rao, R.Mantle xenoliths from the Kodamali kimberlite pipe, Bastar Craton, central India: evidence for decompression melting and crustal contamination mantleGoldschmidt Conference 2009, p. A66 Abstract.IndiaMelting
DS201012-0100
2010
Mainkar, D.Chalapathi Rao, N.V., Lehmann, B., Mainkar, D., Belyatsky, B.Petrogenesis of the end Cretaceous Diamondiferous Behradih kimberlite, central India: implication for the plume lithosphere interactions in the Bastar craton?International Dyke Conference Held Feb. 6, India, 1p. AbstractIndiaMineral chemistry
DS201012-0101
2010
Mainkar, D.Chalapathi Rao, N.V., Lehmann, B., Mainkar, D., Belyatsky, B.Petrogenesis of the end Cretaceous Diamondiferous Behradih orangeite pipe: implications for mantle plume - lithosphere interaction in the Bastar craton, India.Contributions to Mineralogy and Petrology, Vol. 161, pp. 721-742.IndiaOrangeite
DS201012-0430
2010
Mainkar, D.Lehman, B., Burgess, R., Frei, D., Belyatsky, B., Mainkar, D., Chalapthi Rao, N.V., Heaman, L.M.Diamondiferous kimberlites in central India synchronous with Deccan flood basalts.Earth and Planetary Science Letters, Vol. 290, 1-2, Feb. 15, pp. 142-149.IndiaMineral chemistry
DS201012-0431
2010
Mainkar, D.Lehmann, B., Burgess, R., Frei, D., Belyatsky, B., Mainkar, D., Chalapthi Rao, N.V., Heaman, L.M.Diamondiferous kimberlites in central India synchronous with Deccan flood basalts.International Dyke Conference Held Feb. 6, India, 1p. AbstractIndiaDharwar and Bundelkhand cratons
DS201212-0119
2012
Mainkar, D.Chalapathi Rao, N.V., Lehmann, B., Belousova, E., Frei, D., Mainkar, D.Petrology, bulk rock geochemistry, indicator mineral composition and zircon U-Pb geochronology of the end Cretaceous Diamondiferous Mainpur orangeites, Bastar Craton, Central India.10th. International Kimberlite Conference Feb. 6-11, Bangalore India, AbstractIndiaDeposit - Mainpur
DS201212-0120
2012
Mainkar, D.Chalapathi Rao, N.V., Lehmann, B., Mainkar, D., Panwar, B.K.Diamond facies chrome spinel from the Tokapal kimberlite, Indravati basin, central India and its petrological significance.Mineralogy and Petrology, Vol. 105, 3-4, pp. 121-133.IndiaDeposit - Tokapal
DS201212-0432
2012
Mainkar, D.Mainkar, D., Gupta, T., Patel, S.C., Lehmann, B., Diwan, P., Kaminsky, F.V.Physical and infrared characteristics of diamonds from Bahradih kimberlite, Bastar Craton, India.10th. International Kimberlite Conference Held Bangalore India Feb. 6-11, Poster abstractIndiaDeposit - Behradih
DS201312-0567
2013
Mainkar, D.Mainkar, D., Gupta, T., Patel, S.C.Diamonds from the Behradih kimberlite pipe, Bastar craton, India: a reconnaissance study.Proceedings of the 10th. International Kimberlite Conference, Vol. 1, Special Issue of the Journal of the Geological Society of India,, Vol. 1, pp. 309-316.IndiaDeposit - Behradih
DS201412-0118
2013
Mainkar, D.Chalapathi Rao, N.V., Lehmann, B., Panwar, B.K., Kumar, A., Mainkar, D.Tokapal tuff facies kimberlite, Baston craton, central India: a nickel prospect?Journal of the Geological Society of India, Vol. 82, 6, pp. 595-600.IndiaDeposit - Tokapal
DS201901-0075
2018
Mainkar, D.Shaikh, A.M., Patel, S.C., Bussweiler, Y., Kumar, S.P., Tappe, S., Ravi, S., Mainkar, D.Olivine trace element compositions in diamondiferous lamproites from India: proxies for magma origins and the nature of the lithospheric mantle beneath the Bastar and Dharwar cratons.Lithos, doi.org.10.1016/j.lithos.2018.11.026Indiadeposit - Wajrakarur, Mainpur

Abstract: The ~1100?Ma CC2 and P13 lamproite dykes in the Wajrakarur Kimberlite Field (WKF), Eastern Dharwar Craton, and ~65?Ma Kodomali and Behradih lamproite diatremes in the Mainpur Kimberlite Field (MKF), Bastar Craton share a similar mineralogy, although the proportions of individual mineral phases vary significantly. The lamproites contain phenocrysts, macrocrysts and microcrysts of olivine set in a groundmass dominated by diopside and phlogopite with a subordinate amount of spinel, perovskite, apatite and serpentine along with rare barite. K-richterite occurs as inclusion in olivine phenocrysts in Kodomali, while it is a late groundmass phase in Behradih and CC2. Mineralogically, the studied intrusions are classified as olivine lamproites. Based on microtextures and compositions, three distinct populations of olivine are recognised. The first population comprises Mg-rich olivine macrocrysts (Fo89-93), which are interpreted to be xenocrysts derived from disaggregated mantle peridotites. The second population includes Fe-rich olivine macrocrysts (Fo82-89), which are suggested to be the product of metasomatism of mantle wall-rock by precursor lamproite melts. The third population comprises phenocrysts and overgrowth rims (Fo83-92), which are clearly of magmatic origin. The Mn and Al systematics of Mg-rich olivine xenocrysts indicate an origin from diverse mantle lithologies including garnet peridotite, garnet-spinel peridotite and spinel peridotite beneath the WKF, and mostly from garnet peridotite beneath the MKF. Modelling of temperatures calculated using the Al-in-olivine thermometer for olivine xenocrysts indicates a hotter palaeogeotherm of the SCLM beneath the WKF (between 41 and 43?mW/m2) at ~1100?Ma than beneath the MKF (between 38 and 41?mW/m2) at ~65?Ma. Further, a higher degree of metasomatism of the SCLM by precursor lamproite melts has occurred beneath the WKF compared to the MKF based on the extent of CaTi enrichment in Fe-rich olivine macrocrysts. For different lamproite intrusions within a given volcanic field, lower Fo olivine overgrowth rims are correlated with higher phlogopite plus oxide mineral abundances. A comparison of olivine overgrowth rims from the two fields shows that WKF olivines with lower Fo content than MKF olivines are associated with increased XMg in spinel and phlogopite and vice versa. Melt modelling indicates relatively Fe-rich parental melt for WKF intrusions compared to MKF intrusions. The Ni/Mg and Mn/Fe systematics of magmatic olivines indicate derivation of the lamproite melts from mantle source rocks with a higher proportion of phlogopite and/or lower proportion of orthopyroxene for the WKF on the Eastern Dharwar Craton compared to those for the MKF on the Bastar Craton. This study highlights how olivine cores provide important insights into the composition and thermal state of cratonic mantle lithosphere as sampled by lamproites, including clues to elusive precursor metasomatic events. Variable compositions of olivine rims testify to the complex interplay of parental magma composition and localised crystallisation conditions including oxygen fugacity variations, co-crystallisation of groundmass minerals, and assimilation of entrained material.
DS201812-2878
2018
Mainkar, D. RaviShaikh, A.M., Patel, S.C., Bussweiler, Y., Kumar, S.P.K., Tappe, S., Mainkar, D. Ravi, S.Olivine trace element compositions in diamondiferous lamproites from India: proxies for magma origins and the nature of the lithosphere mantle beneath the Bastar and Dharwar cratons. CC2 and P13 Wajrakarur, Kodomali, Behradih Mainpur Lithos, doi:10.1016/j. lithos.2018.11.026 35p.Indiadeposit - Wajrakarur, Mainpur

Abstract: The ~1100 Ma CC2 and P13 lamproite dykes in the Wajrakarur Kimberlite Field (WKF), Eastern Dharwar Craton, and ~65 Ma Kodomali and Behradih lamproite diatremes in the Mainpur Kimberlite Field (MKF), Bastar Craton share a similar mineralogy, although the proportions of individual mineral phases vary significantly. The lamproites contain phenocrysts, macrocrysts and microcrysts of olivine set in a groundmass dominated by diopside and phlogopite with a subordinate amount of spinel, perovskite, apatite and serpentine along with rare barite. K-richterite occurs as inclusion in olivine phenocrysts in Kodomali, while it is a late groundmass phase in Behradih and CC2. Mineralogically, the studied intrusions are classified as olivine lamproites. Based on microtextures and compositions, three distinct populations of olivine are recognised. The first population comprises Mg-rich olivine macrocrysts (Fo89-93), which are interpreted to be xenocrysts derived from disaggregated mantle peridotites. The second population includes Fe-rich olivine macrocrysts (Fo82-89), which are suggested to be the product of metasomatism of mantle wall-rock by precursor lamproite melts. The third population comprises phenocrysts and overgrowth rims (Fo83-92), which are clearly of magmatic origin. The Mn and Al systematics of Mg-rich olivine xenocrysts indicate an origin from diverse mantle lithologies including garnet peridotite, garnet-spinel peridotite and spinel peridotite beneath the WKF, and mostly from garnet peridotite beneath the MKF. Modelling of temperatures calculated using the Al-in-olivine thermometer for olivine xenocrysts indicates a hotter palaeogeotherm of the SCLM beneath the WKF (between 41 and 43 mW/m2) at ~1100 Ma than beneath the MKF (between 38 and 41 mW/m2) at ~65 Ma. Further, a higher degree of metasomatism of the SCLM by precursor lamproite melts has occurred beneath the WKF compared to the MKF based on the extent of CaTi enrichment in Fe-rich olivine macrocrysts. For different lamproite intrusions within a given volcanic field, lower Fo olivine overgrowth rims are correlated with higher phlogopite plus oxide mineral abundances. A comparison of olivine overgrowth rims from the two fields shows that WKF olivines with lower Fo content than MKF olivines are associated with increased XMg in spinel and phlogopite and vice versa. Melt modelling indicates relatively Fe-rich parental melt for WKF intrusions compared to MKF intrusions. The Ni/Mg and Mn/Fe systematics of magmatic olivines indicate derivation of the lamproite melts from mantle source rocks with a higher proportion of phlogopite and/or lower proportion of orthopyroxene for the WKF on the Eastern Dharwar Craton compared to those for the MKF on the Bastar Craton. This study highlights how olivine cores provide important insights into the composition and thermal state of cratonic mantle lithosphere as sampled by lamproites, including clues to elusive precursor metasomatic events. Variable compositions of olivine rims testify to the complex interplay of parental magma composition and localised crystallisation conditions including oxygen fugacity variations, co-crystallisation of groundmass minerals, and assimilation of entrained material.
DS2001-0091
2001
MainpriceBascou, J., Barruol, Vauchez, Mainprice, EgydiosilvaEBSD measured lattice preferred orientations and seismic properties of eclogitesTectonophysics, Vol. 342, No. 2, pp. 61-80.GlobalGeophysics - seismics, Eclogites
DS1991-1005
1991
Mainprice, D.Lloyd, G.E., Schmidt, N.H., Mainprice, D., Prior, D.J.Crystallographic texturesMineralogical Magazine, Vol. 55, pp. 331-345GlobalTextures, Crystallography -review not specific to diamonds
DS1993-0957
1993
Mainprice, D.Mainprice, D., Silver, P.G.Interpretation of SKS -waves using samples from the subcontinentallithosphere.Physics of the Earth and Planetary Interiors, Special issue on Dynamics of, Vol. 78, No. 3-4, July pp. 257-280.MantleGeophysics -seismics, Lithosphere, anisotropy
DS1998-0109
1998
Mainprice, D.Ben Ismail, W., Mainprice, D.An olivine fabric database: an interpretative frame for upper mantleseismology.7th International Kimberlite Conference Abstract, pp. 70-72.MantlePetrophysical database, tectonics, Peridotite
DS1998-0110
1998
Mainprice, D.Ben Ismail, W., Mainprice, D., Barruol, G., Boyd, J.Lithospheric mantle anisotropy of the Kaapvaal Craton, from lattice preferred orientation analysis.7th International Kimberlite Conference Abstract, pp. 73-75.South AfricaTomography - seismic, Olivine
DS1998-0662
1998
Mainprice, D.Ismail, W.B., Mainprice, D.An olivine fabric database: an overview of upper mantle fabrics and seismicanisotropy.Tectonophysics, Vol. 296, No. 1-2, . Oct. 30, pp. 145-158.MantleXenoliths, Magmatism
DS1998-0921
1998
Mainprice, D.Mainprice, D., Barruol, G., Ismail, W.B., Lloyd, G.Automatic crystal orientation mapping of kimberlite nodules using electron back scattererd diffraction..7th International Kimberlite Conference Abstract, pp. 535-6.GlobalKimberlite nodules, Spectroscopy - scanning electron microscope (SEM), EBSP
DS2001-0103
2001
Mainprice, D.Benismail, W., Barruloi, G., Mainprice, D.The Kaapvaal Craton seismic anisotropy: petrophysical analyses of upper mantle kimberlite nodules.Geophysical Research Letters, Vol. 28, No. 13, July 1, pp. 2497-2500.South AfricaGeophysics - seismics, Nodules
DS2002-0113
2002
Mainprice, D.Bascou, J., Tommasi, A., Mainprice, D.Plastic deformation and development of clinopyroxene lattic preferred orientations in eclogites.Journal of Structural Geology, Vol.24,8,pp. 1357-68.GlobalEclogites - omphacite lattics, Mineralogy
DS2003-0464
2003
Mainprice, D.Gibert, B., Sepold, U., Tommasi, A., Mainprice, D.Thermal diffusivity of upper mantle rocks: influence of temperature, pressure and theJournal of Geophysical Research, Vol. 108, 8, ECV 1 , DOI 10.1029/2002JB002108MantleGeothermometry
DS200412-0661
2003
Mainprice, D.Gibert, B., Sepold, U., Tommasi, A., Mainprice, D.Thermal diffusivity of upper mantle rocks: influence of temperature, pressure and the deformation fabric.Journal of Geophysical Research, Vol. 108, 8, ECV 1 , DOI 10.1029/2002 JB002108MantleGeothermometry
DS200512-0679
2005
Mainprice, D.Mainprice, D., Tommasi, A., Couvy, H., Cordier, P., Frost, D.J.Pressure sensitivity of olivine slip systems and seismic anisotropy of Earth's upper mantle.Nature, No. 7027, Feb. 17, pp. 731-2.MantleOlivine
DS200712-0670
2007
Mainprice, D.Mainprice, D., Le Page, Y., Rodgers, J., Jouanna, P.Predicted elastic properties of hydrous D phase at mantle pressures: implications for the anisotropy of subducted slabs near 670 km discontinuity and in the lower mantle.Earth and Planetary Science Letters, Vol. 259, 3-4, pp. 283-296.MantleSubduction
DS200712-0671
2007
Mainprice, D.Mainprice, D., Le Page, Y., Rodgers, J., Jouanna, P.Predicted elastic properties of hydrous D phase at mantle pressures: implications for the anisotropy of subducted slabs near 670 km discontinuity and in the lower mantle.Earth and Planetary Science Letters, Vol. 259, 3-4, pp. 283-296.MantleSubduction
DS200812-0702
2008
Mainprice, D.Mainprice, D., Tommasi, A., Ferre, D., Carrez, P., Cordier, P.Predicted glide systems and crystal preferred orientations of polycrystalline silicate Mg perovskite at high pressure: implications for seismic anisotropyEarth and Planetary Science Letters, Vol. 271, 1-4, pp. 135-144.MantlePerovskite - lower mantle
DS200812-1155
2008
Mainprice, D.Tasaka, M., Michibayashi, K., Mainprice, D.B type olivine fabrics developed in the fore-arc side of the mantle wedge along a subducting slab.Earth and Planetary Science Letters, Vol. 272, 3-4, pp. 747-757.MantleSubduction
DS201312-0919
2013
Mainprice, D.Tommasi, A., Baptiste, V., Soustelle, V., Le Roux, V., Mainprice, D., Vauchez, A.Heterogeneity and anisotropy in the lithospheric mantle.Goldschmidt 2013, AbstractMantleGeophysics
DS201412-0127
2014
Mainprice, D.Chheda, T.D., Mookherjee, M., Mainprice, D., Dos Santos, A.M., Molaison, J.J., Chantel, J., Manthilake, G., Bassett, W.A.Structure and elasticity of phlogopite under compression: geophysical implications.Physics of the Earth and Planetary Interiors, Vol. 233, pp. 1-12.MantleGeophysics
DS201412-0253
2014
Mainprice, D.Frets, E.C., Tommasi, A., Garrido, C.J., Vauchez, A., Mainprice, D., Targuisti, K., Amri, I.The Beni Boussera peridotite ( Rif belt, Morocco): an oblique slip low angle shear zone thinning the subcontinental mantle lithosphere.Journal of Petrology, Vol. 55, 2, pp. 283-313.Africa, MoroccoPeridotite
DS201704-0616
2017
Mainprice, D.Almqvist. B.S.G., Mainprice, D.Seismic properties and anisotropy of the continental crust: predictions based on mineral texture and rock microstructure.Reviews of Geophysics, in press availableMantleGeophysics - seismic

Abstract: Progress in seismic methodology and ambitious large-scale seismic projects are enabling high-resolution imaging of the continental crust. The ability to constrain interpretations of crustal seismic data is based on laboratory measurements on rock samples and calculations of seismic properties. Seismic velocity calculations and their directional dependence are based on the rock micro fabric, which consists of mineral aggregate properties including crystallographic preferred orientation (CPO), grain shape and distribution, grain boundary distribution, and misorientation within grains. Single mineral elastic constants and density are crucial for predicting seismic velocities, preferably at conditions that span the crust. However, high temperature and pressure properties are not as common as elastic constants at standard temperature and pressure (STP) at atmospheric conditions. Continental crust has a very diverse mineralogy, however a select number appear to dominate seismic properties because of their high volume fraction contribution. Calculations of micro fabric-based seismic properties and anisotropy are performed with averaging methods that in their simplest form takes into account the CPO and modal mineral composition. More complex methods can take into account other microstructural characteristics, including the grain shape and distribution of mineral grains, and cracks and pores. A challenge for the geophysics and rock physics communities is the separation of intrinsic factors affecting seismic anisotropy, due to properties of crystals within a rock and apparent sources due to extrinsic factors like cracks, fractures and alteration. This is of particular importance when trying to deduce the state of crustal composition and deformation from seismic parameters.
DS201707-1302
2017
Mainprice, D.Almqvist, B.S.G., Mainprice, D.Seismic properties and anisotropy of the continental crust: predictions based on mineral texture and rock microstructure.Reviews of Geophysics, in press available 43p.Mantlegeophysics - seismics

Abstract: Progress in seismic methodology and ambitious large-scale seismic projects are enabling high-resolution imaging of the continental crust. The ability to constrain interpretations of crustal seismic data is based on laboratory measurements on rock samples and calculations of seismic properties. Seismic velocity calculations and their directional dependence are based on the rock micro fabric, which consists of mineral aggregate properties including crystallographic preferred orientation (CPO), grain shape and distribution, grain boundary distribution, and misorientation within grains. Single mineral elastic constants and density are crucial for predicting seismic velocities, preferably at conditions that span the crust. However, high temperature and pressure properties are not as common as elastic constants at standard temperature and pressure (STP) at atmospheric conditions. Continental crust has a very diverse mineralogy, however a select number appear to dominate seismic properties because of their high volume fraction contribution. Calculations of micro fabric-based seismic properties and anisotropy are performed with averaging methods that in their simplest form takes into account the CPO and modal mineral composition. More complex methods can take into account other microstructural characteristics, including the grain shape and distribution of mineral grains, and cracks and pores. A challenge for the geophysics and rock physics communities is the separation of intrinsic factors affecting seismic anisotropy, due to properties of crystals within a rock and apparent sources due to extrinsic factors like cracks, fractures and alteration. This is of particular importance when trying to deduce the state of crustal composition and deformation from seismic parameters.
DS1982-0396
1982
Mainprice, D.H.Marie, A.M., Mainprice, D.H., Sobolev, N.V.A Transmission Electron Microscopy Study of Olivine Inclusions in Diamond.Proceedings of Third International Kimberlite Conference, TERRA COGNITA, ABSTRACT VOLUME., Vol. 2, No. 3, P. 200, (abstract.).RussiaKimberlite, Udachnaya
DS2003-0656
2003
Mainproce, D.Ji, S., Saruwateri, K., Mainproce, D., Wirth, R., Xu, Z., Xia, B.Microstructures, petrofabrics and seismic properties of ultra high pressure eclogitesTectonophysics, Vol. 370, 1-4, pp. 49-76.ChinaGeophysics - seismics, UHP, subduction
DS200412-0915
2003
Mainproce, D.Ji, S., Saruwateri, K., Mainproce, D., Wirth, R., Xu, Z., Xia, B.Microstructures, petrofabrics and seismic properties of ultra high pressure eclogites from Sulu region, China: implications forTectonophysics, Vol. 370, 1-4, pp. 49-76.ChinaGeophysics - seismics UHP, subduction
DS200812-0490
2008
Mainville, A.Huang, J., Veronneau, M., Mainville, A.Assessment of systematic errors in the surface gravity anomalies over North America using the GRACE gravity model.Geophysical Journal International, Vol. 175, 1, pp. 46-54.United States, CanadaGeophysics - gravity
DS1994-1089
1994
Mainwood, A.Mainwood, A.Electronic band structure of diamondProperties and growth of diamond, G. Davies, pp. 3-8.GlobalDiamond, Bulk properties of natural isotope diamond
DS1994-1090
1994
Mainwood, A.Mainwood, A.Optical constants of diamondProperties and growth of diamond, G. Davies, pp. 9-12.GlobalDiamond, Bulk properties of natural isotope diamond
DS201012-0465
2010
Mainwood, A.Mainwood, A., Newton, M.E., Stoneham, M.Science's gem: diamond science 2009.Journal of Physics Condensed Matter, Vol. 21, 36, pp. 360301-304.TechnologyReview
DS201012-0210
2010
Mair, J.L.Friis, H., Mair, J.L.Ilmaussaq alkaline complex, a unique rare element deposit.International Workshop Geology of Rare Metals, held Nov9-10, Victoria BC, Open file 2010-10, extended abstract pp.37-39.Europe, GreenlandAlkalic
DS201012-0466
2010
Mair, P.Mair, P., Konzett, J., Hauzenberger, Ch.Metasomatic titanates associated with Cl rich amphibole and phlogopite in a multiply metasomatized garnet lherzolite from Letseng la Terae Lesotho.International Mineralogical Association meeting August Budapest, abstract p. 525.Africa, LesothoMineral chemistry
DS201412-0374
2014
Maisano, J.A.Howarth, G.H., Sobolev, N.V., Pernet-Fisher, J.F., Barry, P.H., Penumado, D., Puplampu, S., Ketcham, R.A., Maisano, J.A., Taylor, D., Taylor, L.A.The secondary origin of diamonds: multi-modal radiation tomography of Diamondiferous mantle eclogites.International Geology Review, Vol. 56, 9, pp. 1172-1180.Russia, Siberia3D
DS201504-0202
2015
Maisano, J.A.Howarth, G.H., Sobolev, N.V., Pernet-Fisher, J.F., Ketcham, R.A., Maisano, J.A., Pokhilenko, L.N., Taylor, D.3-D X-ray tomography of Diamondiferous mantle eclogite xenoliths, Siberia: a review.Journal of Asian Earth Sciences, Vol. 101, 1, pp. 39-67.RussiaDeposit - Udachnaya
DS1984-0472
1984
Maisonpierre, R.O'D.Maisonpierre, R.O'D.Central African RepublicMining Annual Review., FOR 1983, JUNE PP. 395-396.West Africa, Central African RepublicDiamond Production
DS201112-0510
2011
Maiter, J.Kelemen, P.B., Maiter, J., Sireil, E.E., Rudge, J.F., Curry, W.B., Blusztajn, J.Rates and mechanisms of mineral carbonation in peridotite: natural processes and recipes for enhanced, in situ CO2 capture and storage.Annual Review of Earth and Planetary Sciences, Vol. 39, pp. 545-576.MantleMineral carbonation
DS1997-0596
1997
Maithani, P.B.Khandelwal, M.K., Maithani, P.B., Pant, P.C., et al.Geological and geochemical studies on carbonatites and rocks of carbonatitic affinity from areas north...Journal of Geological Society India, Vol. 50, Sept., pp. 307-313.India, Madhya Pradesh, GujaratNarmada lineament, Carbonatite
DS1999-0437
1999
Maitra, M.Maitra, M., Chattopadhyay, B.Experimental studies of lamproites in presence of variable volatiles and doping with carbonRecords of Geological Society India, Vol. 133, No. 2, p. 2. (1p)IndiaLamproites, Petrology
DS1993-0958
1993
Maitsev, K.A.Maitsev, K.A., Kluev, Y.A.The degree of nitrogen aggregation in diamonds and the features of diamondformation.(Russian)Geochemistry International (Geokhimiya), (Russian), No. 9, September pp. 1254-1356.RussiaDiamond morphology, Nitrogen
DS200812-0703
2008
Maj, S.Maj, S.Remarks on the thermal conductivity and heat flow density of the Indian Craton.Acta Geophysica, Vol. 56, 4, pp. 994-999.IndiaGeothermometry
DS2001-0720
2001
Majaule, T.Majaule, T., Hanson, Key, Singletary, Martin, BowringThe Magondi belt in northeast Botswana: regional relations and new geochronological dat a from Sua PanJournal of African Earth Sciences, Vol. 32, No. 2, pp. 257-67.BotswanaOrogeny, Geochronology - mentions diamond area
DS2003-0687
2003
Majaule, T.Kampunzu, A.B., Tombale, A.R., Zhai, M., Bagai, Z., Majaule, T., Modisi, M.P.Major and trace element geochemistry of plutonic rocks from Francistown, NELithos, Vol. 71, 2-4, pp. 431-460.ZimbabweTectonics
DS200412-0949
2003
Majaule, T.Kampunzu, A.B., Tombale, A.R., Zhai, M., Bagai, Z., Majaule, T., Modisi, M.P.Major and trace element geochemistry of plutonic rocks from Francistown, NE Botswana: evidence for a Neoarchean continental actiLithos, Vol. 71, 2-4, pp. 431-460.Africa, ZimbabweTectonics
DS200412-0021
2004
Majer, V.Altherr, R., Meyer, H.P., Holl, A., Volker, F., Alibert, C., McCulloch, M.T., Majer, V.Geochemical and Sr Nd Pb isotopic characteristics of Late Cenozoic leucite lamproites from the East European Alpine belt ( MacedContributions to Mineralogy and Petrology, Vol. 147, 1, pp. 58-73.Europe, MacedoniaLamproite, geodynamics
DS201312-0087
2013
Majka, J.Boskabadi, A., Pitcairn, I.K., Stern, R.J., Azer, M.K., Broman, C., Mohamed, F.H., Majka, J.Carbonatite crystallization and alteration in the Tarr carbonatite-albitite complex, Sinai Peninsula, Egypt. ( Arabian-Nubian shield)Precambrian Research, Vol. 239, pp. 24-41.Africa, EgyptCarbonatite
DS201502-0076
2014
Majka, J.Majka, J., Rosen, A., Janak, M., Froitzheim, N., Klonowska, I., Manecki, M., Sasinkova, V., Yoshida, K.Microdiamond discovered in the Seve Nappe ( Scandinavian Caledonides) and its exhumation by the "vacuum-cleaner" mechanism.Geology, Vol. 42, 12, pp. 1107-1110.Europe, SwedenSubduction, microdiamond
DS201505-0237
2014
Majka, J.Majka, J., Rosen, A., Janak, M., Froitzheim, N., Klonowska, I., Maneck, M., Sasinkova, V., Yoshida, K.Microdiamond discovered in the Seve Nappe (Scandinavian Caledonides) and its exhumation by the "vacuum-cleaner" mechanism.Geology, Vol. 42, 12, pp. 1107-110.EuropeMicrodiamonds
DS201702-0221
2017
Majka, J.Klonowska, I., Janak, M., Majka, J., Petrik, I., Froitzheim, N., Gee, D.G., sasinkova, V.Microdiamond on Areskutan confirms regional UHP metamorphism in the Seve Nappe complex of the Scandinavian Caledonides.Journal of Metamorphic Geology, in press availableEurope, Sweden, NorwayUHP

Abstract: Metamorphic diamond in crustal rocks provides important information on the deep subduction of continental crust. Here we present a new occurrence of diamond within the Seve Nappe Complex of the Scandinavian Caledonides, on Åreskutan in Jämtland County, Sweden. Microdiamond is found in-situ as single and composite (diamond + carbonate) inclusions within garnet, in kyanite-bearing paragneisses. The rocks preserve the primary peak pressure assemblage of Ca,Mg-rich garnet + phengite + kyanite + rutile, with polycrystalline quartz surrounded by radial cracks indicating breakdown of coesite. Calculated P-T conditions for this stage are 830-840 °C and 4.1-4.2 GPa, in the diamond stability field. The ultrahigh-pressure (UHP) assemblage has been variably overprinted under granulite facies conditions of 850-860 °C and 1.0-1.1 GPa, leading to formation of Ca,Mg-poor garnet+biotite+ plagioclase+K-feldspar+sillimanite+ilmenite+quartz. This overprint was the result of nearly isothermal decompression, which is corroborated by Ti-in-quartz thermometry. Chemical Th-U-Pb dating of monazite yields ages between 445 and 435 Ma, which are interpreted to record post-UHP exhumation of the diamond-bearing rocks. The new discovery of microdiamond on Åreskutan, together with other evidence of ultrahigh-pressure metamorphism (UHPM) within gneisses, eclogites and peridotites elsewhere in the Seve Nappe Complex, provide compelling arguments for regional (at least 200 km along strike of the unit). UHPM of substantial parts of this far-travelled allochthon. The occurrence of UHPM in both rheologically weak (gneisses) and strong lithologies (eclogites, peridotites) speaks against the presence of large tectonic overpressure during metamorphism.
DS201703-0422
2017
Majka, J.Klonowska, I., Janak, M., Majka, J., Petrik, I., Froitzheim, N., Gee, D.G., Sasinkova, V.Microdiamond on Areskutan confirms regional UHP metamorphism in the Seve Nappe Complex of the Scandinavian Caledonides.Journal of Metamorphic Geology, in press availableEurope, SwedenMicrodiamond

Abstract: Metamorphic diamond in crustal rocks provides important information on the deep subduction of continental crust. Here, we present a new occurrence of diamond within the Seve Nappe Complex (SNC) of the Scandinavian Caledonides, on Åreskutan in Jämtland County, Sweden. Microdiamond is found in situ as single and composite (diamond+carbonate) inclusions within garnet, in kyanite-bearing paragneisses. The rocks preserve the primary peak pressure assemblage of Ca,Mg-rich garnet+phengite+kyanite+rutile, with polycrystalline quartz surrounded by radial cracks indicating breakdown of coesite. Calculated P-T conditions for this stage are 830-840 °C and 4.1-4.2 GPa, in the diamond stability field. The ultrahigh-pressure (UHP) assemblage has been variably overprinted under granulite facies conditions of 850-860 °C and 1.0-1.1 GPa, leading to formation of Ca,Mg-poor garnet+biotite+plagioclase+K-feldspar+sillimanite+ilmenite+quartz. This overprint was the result of nearly isothermal decompression, which is corroborated by Ti-in-quartz thermometry. Chemical Th-U-Pb dating of monazite yields ages between 445 and 435 Ma, which are interpreted to record post-UHP exhumation of the diamond-bearing rocks. The new discovery of microdiamond on Åreskutan, together with other evidence of ultrahigh-pressure metamorphism (UHPM) within gneisses, eclogites and peridotites elsewhere in the SNC, provide compelling arguments for regional (at least 200 km along strike of the unit) UHPM of substantial parts of this far-travelled allochthon. The occurrence of UHPM in both rheologically weak (gneisses) and strong lithologies (eclogites, peridotites) speaks against the presence of large tectonic overpressure during metamorphism.
DS201707-1340
2017
Majka, J.Klonowska, I., Janak, M., Majka, J., Petrik, I., Froitzheim, N., Gee, D.Microdiamond on Areskutan confirms UHP metamorphism in the Seve Nappe Complex of the Scandinavian Caledonides.Journal of Metamorphic Geology, Vol. 35, 5, pp. 541-564.Europe, SwedenUHP

Abstract: Metamorphic diamond in crustal rocks provides important information on the deep subduction of continental crust. Here we present a new occurrence of diamond within the Seve Nappe Complex of the Scandinavian Caledonides, on Åreskutan in Jämtland County, Sweden. Microdiamond is found in-situ as single and composite (diamond + carbonate) inclusions within garnet, in kyanite-bearing paragneisses. The rocks preserve the primary peak pressure assemblage of Ca,Mg-rich garnet + phengite + kyanite + rutile, with polycrystalline quartz surrounded by radial cracks indicating breakdown of coesite. Calculated P-T conditions for this stage are 830-840 ºC and 4.1-4.2 GPa, in the diamond stability field. The ultrahigh-pressure (UHP) assemblage has been variably overprinted under granulite facies conditions of 850-860 ºC and 1.0-1.1 GPa, leading to formation of Ca,Mg-poor garnet + biotite + plagioclase + K-feldspar + sillimanite + ilmenite + quartz. This overprint was the result of nearly isothermal decompression, which is corroborated by Ti-in-quartz thermometry. Chemical Th-U-Pb dating of monazite yields ages between 445 and 435 Ma, which are interpreted to record post-UHP exhumation of the diamond-bearing rocks. The new discovery of microdiamond on Åreskutan, together with other evidence of ultrahigh-pressure metamorphism (UHPM) within gneisses, eclogites and peridotites elsewhere in the Seve Nappe Complex, provide compelling arguments for regional (at least 200 km along the unit) UHPM of substantial parts of this far-travelled allochthon. The occurrence of UHPM in both rheologically weak (gneisses) and strong lithologies (eclogites, peridotites) speaks against the presence of large tectonic overpressure during metamorphism.
DS201709-2018
2017
Majka, J.Klonowska, I., Janek, M., Majka, J., Petrik, I., Froitzheim, N., Gee, D.G., Sasinkova, V.Microdiamond on Areskutan confirms regional UHP metamorphism in the Seve Nappe Complex of the Scandinavian Caledonides.Journal of Metamorphic Geology, Vol. 35, 5, pp. 541-564.Europe, Scandinaviamicrodiamond

Abstract: Metamorphic diamond in crustal rocks provides important information on the deep subduction of continental crust. Here, we present a new occurrence of diamond within the Seve Nappe Complex (SNC) of the Scandinavian Caledonides, on Åreskutan in Jämtland County, Sweden. Microdiamond is found in situ as single and composite (diamond+carbonate) inclusions within garnet, in kyanite-bearing paragneisses. The rocks preserve the primary peak pressure assemblage of Ca,Mg-rich garnet+phengite+kyanite+rutile, with polycrystalline quartz surrounded by radial cracks indicating breakdown of coesite. Calculated P–T conditions for this stage are 830–840 °C and 4.1–4.2 GPa, in the diamond stability field. The ultrahigh-pressure (UHP) assemblage has been variably overprinted under granulite facies conditions of 850–860 °C and 1.0–1.1 GPa, leading to formation of Ca,Mg-poor garnet+biotite+plagioclase+K-feldspar+sillimanite+ilmenite+quartz. This overprint was the result of nearly isothermal decompression, which is corroborated by Ti-in-quartz thermometry. Chemical Th–U–Pb dating of monazite yields ages between 445 and 435 Ma, which are interpreted to record post-UHP exhumation of the diamond-bearing rocks. The new discovery of microdiamond on Åreskutan, together with other evidence of ultrahigh-pressure metamorphism (UHPM) within gneisses, eclogites and peridotites elsewhere in the SNC, provide compelling arguments for regional (at least 200 km along strike of the unit) UHPM of substantial parts of this far-travelled allochthon. The occurrence of UHPM in both rheologically weak (gneisses) and strong lithologies (eclogites, peridotites) speaks against the presence of large tectonic overpressure during metamorphism.
DS201906-1360
2019
Majka, J.Walczak, K., Cuthbert, S., Kooijman, E., Majka, J., Smit, M.A.U-PB zircon age dating of diamond bearing gneiss from Fjortoft reveals repeated burial of the Baltoscandian margin during the Caledonian Orogeny.Geological Magazine, doi.org:10.1017/S0016 756819000268 16p.Europe, Norwaygeochronology

Abstract: The first find of microdiamond in the Nordøyane ultra-high-pressure (UHP) domain of the Western Gneiss Region (WGR) of the Scandinavian Caledonides reshaped tectonic models for the region. Nevertheless, in spite of much progress regarding the meaning and significance of this find, the history of rock that the diamonds were found in is complex and still largely ambiguous. To investigate this, we report U-Pb zircon ages obtained from the exact crushed sample material in which metamorphic diamond was first found. The grains exhibit complicated internal zoning with distinct detrital cores overgrown by metamorphic rims. The cores yielded a range of ages from the Archaean to the late Neoproterozoic / early Cambrian. This detrital zircon age spectrum is broadly similar to detrital signatures recorded by metasedimentary rocks of the Lower and Middle allochthons elsewhere within the orogen. Thus, our dating results support the previously proposed affinity of the studied gneiss to the Seve-Blåhø Nappe of the Middle Allochthon. Metamorphic rims yielded a well-defined peak at 447 ± 2 Ma and a broad population that ranges between c. 437 and 423 Ma. The data reveal a prolonged metamorphic history of the Fjørtoft gneiss that is far more complex then would be expected for a UHP rock that has seen a single burial and exhumation cycle. The data are consistent with a model involving multiple such cycles, which would provide renewed support for the dunk tectonics model that has been postulated for the region.
DS1998-0912
1998
Majola, S.Mabuza, M., Viljoen, K.S., Majola, S.New diamond bearing xenoliths from the Orapa mine, Botswana7th International Kimberlite Conference Abstract, pp. 521-23.BotswanaXenoliths, Deposit - Orapa
DS1960-0736
1966
Major, A.Ringwood, A.E., Major, A.Synthesis of DiamondsAust. Journal of Chem., Vol. 19, No. 10, PP. 1965-1969.AustraliaSynthetic Diamonds
DS1993-0993
1993
Major, T.McCracken, M., Major, T.Diamond mining by Poseidon Bow River Diamond Mine Limited, Bow River WAAustralia Min. Met. Mawby Memorial Volume, Mon. 19, pp. 1449-1452.AustraliaMining, Deposit -Bow River
DS1986-0515
1986
Majorowicz, J.A.Majorowicz, J.A., Jones, F.W., Ertman, M.E., Linville, A., OsadetzHeat flow in the Edmonton-Cold Lake region Of the western Canadian sedimentary basin and the influence of fluid flowProceedings of the Third Canadian/American conference on hydro- geology, pp. 151-158. (Staff of Geological Society of Canada (GSC))AlbertaBasin, Geothermometry -heat flow
DS1987-0038
1987
Majorowicz, J.A.Beach, R.D.W., Jones, F.W., Majorowicz, J.A.Heat flow and heat generation estimates for the Churchill basement of The western Canadian basin inAlberta, CanadaGeothermic, Vol. 16, No. 1, pp. 1-16AlbertaChurchill province, depth to basement, hot spots, Geothermometry
DS1988-0434
1988
Majorowicz, J.A.Majorowicz, J.A., Jones, F.W., Osadetz, K.G.Heat flow environment of the electrical conductivity anomalies in the Williston Basin and occurrence ofhydrocarbonsCan. Soc. Pet. Geol. Bulletin, Vol. 36, No. 1, pp. 86-90AlbertaBasin, Geothermometry -heat flow
DS1993-0959
1993
Majorowicz, J.A.Majorowicz, J.A., Gough, D.I., Lewis, T.J.Electrical conductivity and temperature in the Canadian Cordilleran crustEarth and Planetary Science Letters, Vol. 115, No. 1-4, March pp. 57-64.British Columbia, AlbertaGeophysics, Heat flow
DS1994-1091
1994
Majorowicz, J.A.Majorowicz, J.A., Gough, D.I.A model of crustal conductive structure in the Canadian CordilleraGeophysical Journal International, Vol. 117, pp. 301-312.British ColumbiaGeophysics, Magnetotellurics
DS1998-0922
1998
Majorowicz, J.A.Majorowicz, J.A., Safanda, J.Ground surface temperature history from inversions of underground temperatures: case study....Tectonophysics, Vol. 291, No. 1-4, pp. 187-98.Alberta, Western Canada Sedimentary BasinGeothermometry
DS1999-0438
1999
Majorowicz, J.A.Majorowicz, J.A., Garven, G., Jessop, A., Jessop, C.Present heat flow along a profile across the Western Canada sedimentary basin; the extent hydrodynamic...Geothermics in Basin Analysis, Merriam Ed., pp. 61-79.Alberta, Western CanadaGeothermometry, Basin
DS200712-0672
2007
Majumdar, S.Majumdar, S.Forms of carbon: diamond & graphite.Chemical Weekly, Vol. 52, 41 May 29, pp. 191-206.TechnologyCarbon
DS200712-0673
2007
Majumdar, S.Majumdar, S.Forms of carbon: diamond & graphite.Chemical Weekly, Vol. 52, 41 May 29, pp. 191-206.TechnologyCarbon
DS1999-0439
1999
Majumdar, T.J.Majumdar, T.J., Mohanty, K.K.Regional relief and structural pattern identification over the Indian subcontinent using INSAT VHRRR data.Journal of Geological Society IndiaM., Vol. 53, No. 2, Feb. 1, pp. 205-10.IndiaStructure - landsat imagery
DS200612-0852
2006
Majumdar, T.J.Majumdar, T.J., Bhattacharyya, R., Chatterjee, S.Generation of very high resolution gravity image over the Central Indian Ridge and its tectonic implications.Current Science, Vol. 91, 5, pp. 683-685.IndiaGeophysics - gravity
DS2002-1111
2002
Majundar, R.K.Mullick, M., Majundar, R.K.A FORTRAN program for computing the mise a la masse response over a dyke like body.Computers and Geosciences, Vol. 28, 9, pp. 1119-26.GlobalGeophysics - mise a la masse ( not specific to diamonds
DS2003-0874
2003
Makabo, M.A.H.Manya, S., Makabo, M.A.H.Dating basaltic volcanism in the Neoarchean Sukumaland greenstone belt of thePrecambrian Research, Vol. 121, 1-2. Feb. 28, pp. 35-45.TanzaniaCraton - geochronology
DS2002-0987
2002
Makanga, J.F.Makanga, J.F.The diamond potentialites and investment oppportunities in the mining sector of GabonWorld Diamond Conference (3rd) June 7p., 7p.GabonEconomics - diamond mining
DS1970-0554
1972
Makanjoula, A.A.Makanjoula, A.A.The Mineralogy of Ultramafic and Mafic Nodules from the Pnayam Tertiary Volcanics Benue Plateau State, Nigeria.In: African Geology, Alkalic Rocks And Ring Complexes, University, PP. 127-148.GlobalRelated Rocks
DS1988-0527
1988
Makarenko, N.A.Osipov, P.V., Makarenko, N.A., Korchagin, S.A., Gertner, I.E.New alkaline gabbroid ore bearing massif in Kuznetsk Alatau.(Russian)Geologii i Geofiziki, (Russian), No. 11, (346) November pp. 79-82RussiaAlkaline rocks
DS2003-1434
2003
Makarenko, N.A.Vrublevskii, V.A., Gertner, I.F., Zhuravlev, D.Z., Makarenko, N.A.The Sm Nd isotopic age and source of comagmatic alkaline mafic rocks andDoklady Earth Sciences, Vol. 391A, 6, July-August, pp. 832-5.RussiaGeochronology
DS200412-2065
2003
Makarenko, N.A.Vrublevskii, V.A., Gertner, I.F., Zhuravlev, D.Z., Makarenko, N.A.The Sm Nd isotopic age and source of comagmatic alkaline mafic rocks and carbonatites of Kuznetsk Alatau.Doklady Earth Sciences, Vol. 391A, 6, July-August, pp. 832-5.RussiaGeochronology
DS1986-0516
1986
Makarov, A.S.Makarov, A.S.Trap rock P2- Tl age differentiation in the kimberlite sites of Alakiye andMarkinsk.(Russian)Doklady Academy of Sciences Akademy Nauk SSSR, (Russian), Vol. 290, No. 4, pp. 940-944RussiaKimberlite, Alakiye, Markinsk
DS1986-0517
1986
Makarov, A.S.Makarov, A.S.Differentiated Permian Triassic traps in the Alajit Marhinskkimberlitefield.(Russian)Doklady Academy of Sciences Akademy Nauk SSSR (Russian), Vol. 290, No. 4, pp. 940-944RussiaPetrology
DS1986-0518
1986
Makarov, A.S.Makarov, A.S.Differential traps if the P2 Ti age in alakite-markinskkimberlitefields.(Russian)Doklady Academy of Sciences Akademy Nauk SSSR, (Russian), Vol. 290, No. 4, pp. 940-945RussiaBlank
DS1950-0440
1958
Makarov, N.N.Zrayakovskii, M.S., Makarov, N.N.Tain a Yakutskikh AlmazovMoscow: Gosydarstvennoe Izdat., 110P.RussiaKimberlite, Diamonds, Kimberley
DS1989-0783
1989
Makarov, S.V.Kirichenko, V.T., Makarov, S.V.The Kharamai field: a new region of kimberlite magmatism on the SiberianPlatformSoviet Geology and Geophysics, Vol. 30, No. 11, pp. 31-36RussiaKharamai, Kimberlite genesis
DS1985-0330
1985
Makarova, M.V.Kats, YA.G., Makarova, M.V.A Map of Circular Structures of the World's ContinentsMoscow University of Geol. Bulletin, Vol. 40, No. 6, pp. 32-41RussiaTectonics
DS200512-0625
2005
MakeevLevchenkov, O.A., Gaidamako, I.M., Levskii, L.K., Komarov, Yakovleva, Rizvanova, MakeevU Pb age of zircon from the Mir and 325 Let Yakutii pipes.Doklady Earth Sciences, Vol. 400, 1, pp. 99-101.Russia, YakutiaGeochronology
DS201112-0632
2011
Makeev, A.Makeev, A.The informational significance of studies of diamond accessory minerals.Russian Journal of General Chemistry, Vol. 81, 6, pp. 1315-1327.TechnologyDiamond inclusions
DS1984-0473
1984
Makeev, A.B.Makeev, A.B., Agafanov, L.V., Goncharenko, A.I.The Relation of the Chemical Composition to the Physical Properties of Chrome Spinels in Alpinotypic Ultrabasites.Soviet Geology And Geophysics, Vol. 25, No. 2, PP. 125-129.RussiaMineral Chemistry
DS2002-0988
2002
Makeev, A.B.Makeev, A.B., Ivanuch, Obyden, Saparin, FilippovMineralogy, composition of inclusions and cathodluminescence of carbonado from Bahia State.Geology of Ore Deposits, Vol.44,2,pp.87-102.Brazil, BahiaMineralogy, geochronology, Carbonado
DS2002-0989
2002
Makeev, A.B.Makeev, A.B., Kisel, S.I., Sobolev, V.K., Filippov, V.N., Bryanchaninova, N.I.Native metals in kimberlite pipe aureoles of the Arkhangelsk Diamondiferous provinceDoklady Earth Sciences, Vol. 385A, 6, pp. 714-8.Russia, Kola Peninsula, ArkangelskGeochemistry, Deposit - Arkangel area
DS200912-0465
2009
Makeev, A.B.Makeev, A.B., Andriechev, V.L., Bryanchaninova, N.I.Age of lamprophyres of the Middle Timan: first Rb-Sr data.Doklady Earth Sciences, Vol. 427, 4, pp. 584-587.RussiaLamprophyre
DS201012-0076
2010
Makeev, A.B.Bryanchaninova, N.I., Makeev, A.B.Garnet of the pyrope majorite series.International Mineralogical Association meeting August Budapest, abstract p. 152.Russia, Timan, South America, BrazilUHP
DS201012-0467
2010
Makeev, A.B.Makeev, A.B., Bryanchaninova, N.I.Lamprophyres of Middle Timan, Russia.International Mineralogical Association meeting August Budapest, abstract p. 574.Russia, TimanLamprophyre
DS201312-0568
2012
Makeev, A.B.Makeev, A.B., Kriulina, G.Y.Metal films on the surfaces and within diamond crystals from Arkangelskaya and Yakutian diamond provinces.Geology of Ore Deposits, Vol. 54, 8, pp. 663-673.Russia, YakutiaDeposit - Lomonosovskaya, Archangelsk, Snegurochka, XXIII Congress, Internationalnaya
DS201412-0823
2014
Makeev, B.Shumilova, T., Kis, K.V., Masaitis, V., Isaenko, S., Makeev, B.Onion-like carbon in impact diamonds from the Popigai astrobleme.European Journal of Mineralogy, Vol. 26, 2, pp. 267-277.RussiaLonsdaleite, raman spectroscopy
DS201806-1251
2018
Makeev, B.A.Shunilova, T.G., Isaenko, S.I., Ulyashev, V.V., Kazakov, V.A., Makeev, B.A.After coal diamonds: an enigmatic type of impact diamonds. Kara astrobleme ( Pay-Khoy)European Journal of Mineralogy, Vol. 30, 1, pp. 61-76.Russiameteorites

Abstract: Impact diamonds were discovered in the 70s and are usually accepted as being paramorphs after graphite, resulting in grains of extremely high mechanical quality. A diffusion-less mechanism for the graphite-to-diamond transition under huge pressure has been experimentally realized and theoretically explained. Besides, another type of impact product has received much less attention, namely diamonds formed after coal as a result of the impact. Here we describe after-coal impact diamonds from the giant Kara astrobleme (Pay-Khoy, Russia), which resulted from a large asteroid impact about 70?Ma ago. The impact created a large number of unusual impact diamonds, which are described here for the first time using high-resolution techniques including visible and UV Raman spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM) and transmission electron microscopy (TEM). Two main varieties of after-coal diamonds occur: micrograined (sugar-like, subdivided into coherent and friable) and, as a new type, paramorphs after organic relics. After-coal diamonds differ from after-graphite impact diamonds by the texture, the absence of lonsdaleite, a micro- and nanoporous structure. The sugar-like variety consists of tightly aggregated, well-shaped single nanocrystals. The after-organic diamond paramorphs are characterized by a well-preserved relict organic morphology, sub-nanocrystalline-amorphous sp3-carbon (ta-C) nanocomposites and other specific properties (optical transparence, brown color, very high luminescence, spectral features). Based on the description of after-coal diamonds, we propose a new, polystage formation mechanism: high-velocity coal pyrolysis with hetero-elements removal followed by diffusion-limited crystallization of pure carbon. The similarity of the after-coal diamonds features with carbonado is a strong piece of evidence in support of the impact hypothesis for the origin of carbonado.
DS201907-1573
2019
Makeev, B.A.Shumilova, T.G., Kovalchuk, N.S., Makeev, B.A.Geochemical features of the diamondiferous suevites of the Kara astrobleme ( Pay-Khoy).Doklady Earth Sciences, Vol. 486, 1, pp. 545-548.Russiamicrodiamonds

Abstract: The results of geochemical studies of the diamondiferous suevites of the Kara astrobleme (Pay-Khoy) using a new approach based on “area” microprobe analysis of suevite matrix and consolidated impact melt aggregates with subsequent data processing by multivariate statistic methods are described for the first time. At least three suevite varieties that differ essentially in geomorphology, mineralogy, petrography, and geochemical features have been recognized. The predominant protoliths of the rocks of the target are proposed for these suevite varieties on the basis of integrated data analysis.
DS200912-0174
2009
Makeev, B.A.A.A.Divaev, F.A.K.A., Shumilova, T.A.G.A., Yushkin, N.A.P.A., Makeev, B.A.A.A.First occurrence of diamonds in shonkinite porphyrys of the northern Tamdytau ( Central Kyzylkumy, western Uzbekistan).Doklady Earth Sciences, Vol. 425, 2, pp. 216-218.Russia, UzbekistanDiamond - shonkinite
DS201601-0051
2015
Makeeyev, A.B.Yang, J.S., Wirth, R., Wiedenbeck, M., Griffin, W.L., Meng, F.C., Chen, S.Y., Bai, W.J., Xu, X.X., Makeeyev, A.B., Bryanchaniniova, N.I.Diamonds and highly reduced minerals from chromitite of the Ray-Iz ophiolite of the Polar Urals: deep origin of podiform chromitites and ophiolitic diamonds.Acta Geologica Sinica, Vol. 89, 2, p. 107.Russia, Polar UralsOphiolite
DS200612-0200
2006
Makene, C.Burnard, P., Basset, R., Marty, B., Fischer, T., Palhol, F., Mangasini, F., Makene, C.Xe isotopes in carbonatites: Oldonyo Lengai, East African Rift.Geochimica et Cosmochimica Acta, Vol. 70, 18, p. 1, abstract only.Africa, TanzaniaCarbonatite
DS1985-0379
1985
Makepeace, A.P.Lang, A.R., Kowalski, G., Makepeace, A.P.Recording Diffuse X-ray Reflections with Continuous Synchroton Radiation - an Application to Type 1a Diamond.Phil. Magazine, SECT. A, Vol. 52, No. 1, JULY, PP. 1-L. (LETTER).GlobalMineralogy
DS1991-0950
1991
Makepeace, A.P.Lang, A.R., Moore, M., Makepeace, A.P., Wierzchov, W.On the dilation of synthetic type 1B diamond by substitutional nitrogenimpurityPhil. Transactions Roy. A., Vol. A 337, No. 1648, Dec. 16, pp. 497-520GlobalDiamond synthesis, Nitrogen impurity
DS1998-0923
1998
Makeyev, A.B.Makeyev, A.B.Mineralogy of diamonds from Devonian placer Ichetju, middle Timans, Russia.Ima 17th. Abstract Vol., p. A16. poster abstractRussia, TimanDiamond morphology, alluvials, Deposit - Ichetju
DS2000-0607
2000
Makeyev, A.B.Makeyev, A.B.Metal membranes on natural diamondsIgc 30th. Brasil, Aug. abstract only 1p.Russia, Urals, TimanDiamond - morphology, Deposit - Ichetju
DS2000-0608
2000
Makeyev, A.B.Makeyev, A.B., Dudar, V.A., Bryanchaninova, N.I.Original rocks of Uralian and Timanian diamondsIgc 30th. Brasil, Aug. abstract only 1p.Russia, Urals, TimanDiamond - morphology, Deposit - Ichetju
DS200412-1208
2003
Makeyev, A.B.Makeyev, A.B., Iwanuch, W., Obyden, S.K., Bryachaninova, N.I., Saparin, G.V.Inter relation of diamond and carbonado ( based on study of collections from Brazil and Middle Timan).Doklady Earth Sciences, Vol. 393a, no. 9, pp.1251-5.Russia, South America, BrazilDiamond morphology
DS201012-0468
2010
Makeyev, A.B.Makeyev, A.B.Informative value of the diamonds' minerals - indicators study.International Mineralogical Association meeting August Budapest, abstract p. 185.RussiaDiamond - synthesis
DS201412-0999
2014
Makeyev, A.B.Yang, J., Meng, F., Xu, X., Robinson, P.T., Dilek, Y., Makeyev, A.B., Wirth, R., Wiedenbeck, M., Cliff, J.Diamonds, native elements and metal alloys from chromitites of the Ray-Iz ophiolite of the Polar Urals.Gondwana Research, Vol. 27, 2, pp. 459-485.Asia, TibetUHP ophiolite diamonds
DS201502-0126
2014
Makeyev, A.B.Yang, J., Meng, F., Xu, X., Robinson, P.T., Dilek, Y., Makeyev, A.B., Wirth, R., Wiedenbeck, M., Cliff, J.Diamonds, native elements and metal alloys from chromitites of the Ray-Iz ophiolite of the Polar Urals.Gondwana Research, Vol. 27, 2, pp. 459-485.Russia, UralsChromitite
DS1999-0178
1999
Makeyeva, L.Dricker, I., Vinnik, L., Makeyeva, L.Upper mantle flow in eastern EuropeGeophysical Research Letters, Vol. 27, No. 9, May pp. 1219-22.EuropeGeophysics - seismics, Mantle flow, melting
DS2002-1670
2002
Makeyeva, L.Vinnick, L., Peregoudov, D., Makeyeva, L., Oreshin, S., Roecker, S.Towards 3 D fabric in the continental lithosphere and asthenosphere: the Tien ShanGeophysical Research Letters, Vol. 16, 39, Aug. 15, 10.1029/2001GL014588ChinaGeophysics - seismics
DS200912-0800
2009
Makeyeva, L.Vinnik, L., Oreshin, S., Kosarev, G., Kiselev, S.,Makeyeva, L.Mantle anomalies beneath southern Africa: evidence from seismic S and P receiver functions.Geophysical Journal International, Vol. 179, 1, pp. 279-298.Africa, South AfricaGeophysics - seismics
DS201811-2584
2018
Makeyeva, L.Kosarev, G., Oreshin, S., Vinnik, L., Makeyeva, L.Mantle transition zone beneath the central Tien Shan: lithospheric delamination and mantle plumes.Tectonophysics, Vol. 723, 1, pp. 172-177.Chinaplumes

Abstract: We investigate structure of the mantle transition zone (MTZ) under the central Tien Shan in central Asia by using recordings of seismograph stations in Kyrgyzstan, Kazakhstan and adjacent northern China. We apply P-wave receiver functions techniques and evaluate the differential time between the arrivals of seismic phases that are formed by P to SV mode conversion at the 410-km and 660-km seismic boundaries. The differential time is sensitive to the thickness of the MTZ and insensitive to volumetric velocity anomalies above the 410-km boundary. Under part of the southern central Tien Shan with the lowest S wave velocity in the uppermost mantle and the largest thickness of the crust, the thickness of the MTZ increases by 15-20 km relative to the ambient mantle and the reference model IASP91. The increased thickness is a likely effect of low (about ? 150 K) temperature. This anomaly is indicative of delamination and sinking of the mantle lithosphere. The low temperature in the MTZ might also be a relic of subduction of the oceanic lithosphere in the Paleozoic, but this scenario requires strong coupling and coherence between structures in the MTZ and in the lithosphere during plate motions in the last 300 Myr. Our data reveal a reduction of thickness of the MTZ of 10-15 km under the Fergana basin, in the neighborhood of the region of small-scale basaltic volcanism at the time near the Cretaceous-Paleogene boundary. The reduced thickness of the MTZ is the effect of a depressed 410-km discontinuity, similar to that found in many hotspots. This depression suggests a positive temperature anomaly of about 100-150 K, consistent with the presence of a thermal mantle plume. A similar depression on the 410-km discontinuity is found underneath the Tarim basin.
DS1992-0984
1992
Makeyeva, L.I.Makeyeva, L.I., Vinnik, L.P., Roecker, S.W.Shear-wave splitting and small scale convection in the continental uppermantleNature, Vol. 358, No. 6382, July 9, pp. 144-146MantleGeodynamics, Geophysics -convection
DS1960-0704
1966
Makhilayev, L.V.Makhilayev, L.V., Surina, N.P.Kimberlites of the Maimecha-kotui Province of Ultrabasic Alkaline Rocks of Northern Siberia.Geologii i Geofiziki, No. 8, PP. 45-55.RussiaBlank
DS1995-1794
1995
MakhinSobolev, N.V., Yefimova, E., Reimers, Zakharchenko, MakhinArkhangelsk diamond inclusionsProceedings of the Sixth International Kimberlite Conference Abstracts, pp. 558-560.Russia, ArkangelskDiamond inclusions, Deposit -Lomonosov, Pionerskaya, Karpinski, Pomorskaya
DS1997-1074
1997
MakhinSobolev, N.V., Yefimova, Reimers, Zakharchenko, MakhinMineral inclusions in diamonds of the Arkangelsk kimberlite provinceRussian Geology and Geophysics, Vol. 38, No. 2, pp. 379-393.RussiaDiamond inclusions, Deposit - Zolotitsky, Lomonosov, Karpinsky, Pionerskaya
DS1989-0393
1989
Makhin, A.I.Efimova, E.S., Zakharchenko, O.D., Sobolev, N.V., Makhin, A.I.Inclusions in diamonds from a kimberlite pipe.(Russian)Zap. Vses. Mineral. O-Va, (Russian), Vol. 118, No. 2, pp. 74-76RussiaDiamond morphology, Diamond inclusions
DS1991-1918
1991
Makhin, A.I.Zakarchenko, O.D., Kharkiv, A.D., Botova, M.M., Makhin, A.I.Inclusions of deep seated minerals in diamonds from kimberlite rocks From the northern Russian Platform*(in Russian)Mineral. Zhurn., (Russian), Vol. 13, No. 5, pp. 42-52RussiaPetrology, Diamond inclusions
DS1991-1920
1991
Makhin, A.I.Zarharchenko, O.D., Kharkiv, A.D., Botova, M.M., Makhin, A.I.Inclusions of plutonic minerals in diamonds from kimberlite rocks of the northern east European PlatformProceedings of Fifth International Kimberlite Conference held Araxa June 1991, Servico Geologico do Brasil (CPRM) Special, pp. 579-580RussiaDiamond inclusions, Olivine, coesite, chrome-spinellid
DS1994-0563
1994
Makhin, A.I.Galimov, E.M., Zakharch, O.D., Maltsev, K.A., Makhin, A.I.The isotopic composition of carbon in diamonds from the kimberlitic pipe sat Archangelsk.(Russian)Geochemistry International (Geokhimiya), (Russian), No. 1, pp. 67-74.Russia, Yakutia, ArkangelskGeochronology, Diamond inclusions -carbon
DS1995-1727
1995
Makhin, A.I.Shchukin, V.S., Sobolev, V., Larehence, V.A., Makhin, A.I.Geology of the diamond deposits in the Arkhangelsk region, RussiaSociety for Mining, Metallurgy and Exploration (SME) Meeting, Denver March 1995, abstractRussia, Commonwealth of Independent States (CIS), RussiaDiamond deposits
DS1960-0272
1962
Makhlayev, L.V.Makhlayev, L.V., Volkhov, V.K., Dakhya, L.M.Discovery of the Kimberlites in the Kotui-meimecha DistrictNiiga, Info. Bulletin., No. 26, PP. L6-24, French Geological Survey (BRGM) TRANSLATION No.RussiaBlank
DS1960-0372
1963
Makhlayev, L.V.Makhlayev, L.V., Surina, N.P.Meimicha-kotny Province of Ultrabasic and Alkaline Rocks- A new Region of Kimberlite Magmatism.Doklady Academy of Science USSR, Earth Science Section., Vol. 153, No. L-6, PP. 178-180.RussiaBlank
DS1984-0618
1984
Makho.Rotman, A.J., Serenko, V.P., Okrugin, A.V., Ivanov, A.G., Makho.Garnets from Basite Explosion Pipes of Western YakutiaDoklady Academy of Sciences AKAD. NAUK SSSR., Vol. 276, No. 3, PP. 693-697.RussiaMineralogy
DS1993-1253
1993
Makhorin, A.M.Poltaratskaya, O.L., Makhorin, A.M.The prediction of the kimberlite fields according to deep geoelectrics -1Diamonds of Yakutia, pp. 127-128.Russia, YakutiaGeophysics, Geoelectrics
DS1986-0083
1986
Makhotin, I.L.Bogatikov, O.A., Eremeev, N.V., Makhotin, I.L., et al.Lamproites of Aldan and Central Asia.(Russian)Doklady Academy of Sciences Akademy Nauk SSSR, (Russian), Vol. 290, No. 4, pp. 936-940RussiaLamproite, Petrology
DS1985-0069
1985
Makhotkin, I.L.Bogatikov, O.A., Makhotkin, I.L., Konova, V.A.Lamproites and their position in the classification of magnesium richpotassic rocks. (Russian)Izv. Akad. Nauk SSSR Ser. Geol. (Russian), No. 12, pp. 3-10RussiaLamproite, Potassic
DS1986-0084
1986
Makhotkin, I.L.Bogatikov, O.A., Eremeev, N.V., Makhotkin, I.L., Konova, V.A.Lamproites of Aldan and Middle Asia.(Russian)Doklady Academy of Sciences Akademy Nauk SSSR, (Russian), Vol 290, No. 4, pp. 936-940RussiaLamproites
DS1987-0063
1987
Makhotkin, I.L.Bogatikov, O.A., Kononova, V.A., Makhotkin, I.L., Eremeev, N.V.Rare earth and elements as indicators of the origin of lamproites of central Aldan (USSR).(Russian)Vulkanol. Seismol., (Russian), No. 1, pp. 15-29RussiaLamproites, Rare earths
DS1988-0065
1988
Makhotkin, I.L.Bogatikov, O.A., Kononova, V.A., Makhotkin, I.L.Lamproites. (Russian)Ultrabasic rocks, Magmaticheskiye Gornyye Porody, Izd. Nauka, Moscow, Vol. 5, pp. 217-229RussiaLamproites, Geochemistry
DS1988-0066
1988
Makhotkin, I.L.Bogatikov, O.A., Yeremeyev, N.V., Makhotkin, I.L., Kononova, V.A.Lamproites of the Aldan and central AsiaDoklady Academy of Science USSR, Earth Science Section, Vol. 290, No. 1-6, March pp. 154-157RussiaLamproite, Analyses
DS1989-0133
1989
Makhotkin, I.L.Bogatikov, O.A., Makhotkin, I.L., Kononova, V.A.Lamproites: composition and petrogenetic questions. (Russian)Moscow, Nayka, Monograph, (Russian), pp. 92-100RussiaLamproites, Petrology
DS1989-0134
1989
Makhotkin, I.L.Bogatikov, O.A., Makhotkin, I.L., Kononova, V.A.Lamproites, composition and aspects of petrogenesis.(Russian)Kristal. Kora V Prostranstve i vrement: magmatizm Dokl. Sov. Geol, pp. 92-100. Chem abstracts E1310:082300M CA 153003RussiaLamproites, Genesis
DS1989-0408
1989
Makhotkin, I.L.Eremeyev, N.V., Kononova, V.A., Makhotkin, I.L., Dmitrieva, M.T.Native metals in lamproites of central Aldan.(Russian)Doklady Academy of Sciences Akademy Nauk SSSR, (Russian), Vol. 303, No. 6, pp. 1464-1467RussiaLamproite, Base metals
DS1989-0921
1989
Makhotkin, I.L.Makhotkin, I.L., Arakeliants, M.M., Vladykin, N.V.On the age of lamproites from the Aldanian province. (Russian)Doklady Academy of Sciences Akademy Nauk SSSR, (Russian), Vol. 306, No. 3, pp. 703-707RussiaLamproite, Geochronology
DS1990-0874
1990
Makhotkin, I.L.Kononova, V.A., Makhotkin, I.L., Malov, Y.V., Bogatikov, O.A.Lamproites and petrochemical series of potassium rocks.(Russian)Izves. Akad. Nauk SSSR, (Russian), Ser, Geol. No. 11, November pp. 55-65RussiaLamproites, Petrochemistry
DS1990-0975
1990
Makhotkin, I.L.Makhotkin, I.L., Arakelyants, M.M., Vladykin, N.V.Age of lamproites of the Aldan provinceDoklady Academy of Sciences USSR, Earth Sci. Section, Vol. 306, No. 3, pp. 163-167RussiaLamproites, Geochronology
DS1991-0860
1991
Makhotkin, I.L.Kharkiv, A.D., Zherdev, P.Y., Makhotkin, I.L., Sheremeev, V.F.Pecularities of diamond bearing pipe substance composition Majhgawan(Central India).(Russian)Izvest. Akad. Nauk SSSR, ser. geol., (Russian), No. 3, March pp. 123-132IndiaDiamond genesis, Deposit -Majhgawan
DS1991-0861
1991
Makhotkin, I.L.Kharkiv, A.D., Zherdev, P.Yu., Makhotkin, I.L., Sheremeyev, V.F.Composition of the diamond bearing rocks of the Majhgawan pipe, centralIndiaInternational Geology Review, Vol. 33, No. 3, March pp. 269-278IndiaPipes, Mineral chemistry
DS1992-0985
1992
Makhotkin, I.L.Makhotkin, I.L.The isotopic composition of Strontium and Neodymium in lamproites of Aldan.(Russian)Doklady Academy of Sciences Akademy Nauk SSSR, (Russian), Vol. 325, No. 3, pp. 576-580.RussiaLamproite
DS1993-0960
1993
Makhotkin, I.L.Makhotkin, I.L., Zhuravle, D.Z.Isotopic composition of Strontium and neodymium Diamondiferous kimberlites and melilitites of Arkangelsk region.(Russian)Doklady Academy of Sciences Akademy Nauk SSSR*(in Russian), Vol. 332, No. 4, Oct. pp. 491-495.Russia, ArkangelskGeochronology, Diamond genesis
DS1994-1092
1994
Makhotkin, I.L.Makhotkin, I.L.Isotope composition of Strontium and neodymium in the Aldan lamproitesDoklady Academy of Sciences USSR, Vol. 326, Oct. pp. 167-171.Russia, Aldan, LenaLamproites, Geochronology
DS1995-1148
1995
Makhotkin, I.L.Makhotkin, I.L., Zherdev, P.Yu.New dat a on the composition of alkalic ultramafic rocks of explosion pipes in Arkhangelsk oblast.Doklady Academy of Sciences, Vol. 330, No. 4, May pp. 145-149.Russia, ArkangelskUltramafic, Dike
DS1995-1149
1995
Makhotkin, I.L.Makhotkin, I.L., Zhuravlev, D.Z.Isotopic compositions of Arkhangel'sk region diamond bearing Kimberlites and melilites containing Sr and neodymium.Doklady Academy of Sciences USSR, Vol. 333, No. 8, August, pp. 138-143.Russia, ArkangelskGeochornology, Kimberlites, melilites
DS1997-0718
1997
Makhotkin, I.L.Makhotkin, I.L., Zhuravlev, Sabu\lukov, Zherdev et al.The plume lithosphere interaction as a geodynamic formation model of the Arkangelsk diamond bearing ProvinceDoklady Academy of Sciences, Vol. 353, No. 2, Feb-Mar, pp. 238-42.Russia, Kola Peninsula, ArkangelskTectonics
DS1998-0924
1998
Makhotkin, I.L.Makhotkin, I.L., Podkuiko, Y.A.Kimberlites of the Polar Ural region: a new geochemical type of kimberlitic rocks depleted in trace elements.Doklady Academy of Sciences, Vol. 361A, No. 6, pp. 993-8.Russia, UralsGeochemistry
DS1989-0135
1989
Makhotkin, I.P.Bogatikov, O.A., Makhotkin, I.P., Kononova, V.A.Lamproites, composition and petrogenetic questions.(Russian)in: Crystalline crust in space and time; magmatism, (Russian), Izd. Nauka, Moscow, pp. 91-100RussiaLamproites, Petrology
DS1993-0961
1993
Makhotkin, T.L.Makhotkin, T.L., Zherdev, P.Y.New dat a on alkaline-ultrabasic rocks of pipes from Arkhangelsk region.(Russian)Doklady Academy of Sciences Akademy Nauk SSSR, (Russian), Vol. 329, No. 4, April pp. 484-489.Russia, Yakutia, RussiaAlkaline rocks
DS1986-0679
1986
MakhotkoRotman, A.Ya., Serenko, V.P., Okrugin, A.V., Ivanov, A.G., MakhotkoGarnets from mafic volcanic pipes of western YakutiaDoklady Academy of Science USSR, Earth Science Section, Vol. 276, January pp. 119-122RussiaMineralogy, Analyses
DS1983-0551
1983
Makhotko, V.F.Safronov, A.F., Egorov, K.N., Makhotko, V.F.Pecularities of the Temperature Regime of Kimberlite Melt CrystallizationDoklady Academy of Sciences AKAD. NAUK SSSR., Vol. 269, No. 2, PP. 454-457.RussiaGenesis
DS1984-0625
1984
Makhotko, V.F.Safronov, A.F., Yegorov, K.N., Makhotko, V.F.Thermal Regime of Crystallization of Kimberlite MeltDoklady Academy of Science USSR, Earth Science Section., Vol. 269, No. 1-6, SEPT. PP. 119-121.RussiaUdachnaya, Crystallography, Mineralogy
DS1984-0702
1984
Makhotko, V.F.Spetsius, Z.V., Nikishov, K.N., Makhotko, V.F.Sanidine bearing kyanite eclogites from the Udachnayakimberlitepipe.(Russian)Doklady Academy of Sciences Akademy Nauk SSSR, (Russian), Vol. 279, No. 1, pp. 177-180RussiaEclogite, Sanidine
DS1984-0703
1984
Makhotko, V.F.Spetsius, Z.V., Nikishov, K.N., Makhotko, V.F.Sanidine Bearing Kyanite Eclogite from Kimberlite Pipe Udachnaia.Doklady Academy of Sciences AKAD. NAUK SSSR., Vol. 279, No. 1, PP. 177-180.RussiaInclusions
DS1986-0781
1986
Makhotko, V.F.Spetsius, Z.V., Nikishov, K.N., Makhotko, V.F.Kyanite eclogite with sanadine from the Udachnaya kimberlite pipeDoklady Academy of Science USSR, Earth Science Section, Vol. 279, No. 1-6, pp. 138-141RussiaEclogite
DS1987-0345
1987
Makhotko, V.F.Kharkiv, A.D., Safronov, A.F., Makhotko, V.F.Deep seated xenoliths from the Aikhal kimberlite pipe.(Russian)Doklady Academy of Sciences Akademy Nauk SSSR (Russian), Vol. 295, No. 2, pp. 482-486RussiaGeothermometry, Xenoliths
DS1988-0353
1988
Makhotko, V.F.Kharkiv, A.D., Safronov, A.F., Makhotko, V.F.Plutonic xenoliths from the Aykhal kimberlite pipeDoklady Academy of Science USSR, Earth Science Section, Vol. 295, No. 1-6, Nov. pp. 165-168RussiaAnalyses -garnet, ratios with Cr2O3
DS1995-1071
1995
Makhotko, V.F.Lazebik, K.A., Zayakina, N.V., Makhotko, V.F.A new thorium silicate from carbonatites at the Sirenevyy Kaman charoititedeposit.Doklady Academy of Sciences, Vol. 336, No. 4, Nov., pp. 97-101.Russia, YakutiaAlkaline rocks, Carbonatite -charoite
DS1985-0385
1985
Makhoto, V.F.Lazebnik, K.A., Makhoto, V.F., Lazebnik, Y.D.The First Finding of Priderite in Eastern Siberia.(russian)Mineral. Zhurn., (Russian), Vol. 7, No. 4, pp. 81-83RussiaLamproite
DS1986-0779
1986
Makhoto, V.F.Spetsius, X.V., Nikishov, K.N., Makhoto, V.F.Kyanite eclogite with sanidine from the Udachnaya kimberlite pipeDoklady Academy of Sciences Acad. Science USSR Earth Science Section, Vol. 279, No. 1-6, pp. 138-141South AfricaMineral chemistry, Roberts Victor, Analyses sanidine eclogit
DS1987-0344
1987
Makhoto, V.F.Kharkiv, A.D., Matsyuk, S.S., Safronov, A.F., Makhoto, V.F.Minerals in xenoliths of deep seated rocks from kimberlites oftheInternationial'Naya' pipe, Yakutia.(Russian)Mineral. Zhurn., *UKR., Vol. 9, No. 4, pp. 62-71RussiaBlank
DS1988-0774
1988
Makhotsin, I.L.Yeremeyev, N.V., Kononova, V.A., Makhotsin, I.L., et al.Native metals in lamproites of central AldanDokl. Acad. Sciences USSR Earth Science Section, Vol. 303, No. 6, pp. 167-171RussiaLamproites, Native metals
DS200512-1131
2005
Makhrachev, A.F.Vedin, A.T., Vorobev, V.V., Emelyanov, E.L., Makhrachev, A.F., Potashnikov, A.K., Shlyufman, E.M.X ray luminescence diamond separator with digital signal.Journal of Mining Science, Vol. 40, 6, pp. 633-638.Mining -5 + 2mm in size concentrates
DS1984-0402
1984
Makhumod, A.S.Khakimov, Z.M., Pulatova, D.S., Makhumod, A.S., Levin, A.A., et al.Genealogy of Localized States in Diamond Like CrystalsDoklady Academy of Sciences AKAD. NAUK SSSR., Vol. 279, No. 1, PP. 153-156.RussiaDiamond Cystallography
DS200912-0466
2009
Maki, J.M.Maki, J.M., Tuomisto, F., Kelly, C., Fisher, D., Martineau, P.M.Properties of optically active vacancy clusters in type IIa diamond.Journal of Physics Condensed Matter, in press ( August)TechnologyDiamond - morphology IIa
DS1991-1038
1991
Makinen, J.Makinen, J.Similarity analysis using rank in till geochemistryBulletin. Geological Society Finland, Vol. 63, pt. 1, pp. 49-57FinlandGeochemistry, Analysis
DS200412-1736
2004
Makino, K.Satoh, H., Yamaguchi, Y., Makino, K.Ti substitution mechanism in plutonic oxy-kaersutite from the Larvik alkaline complex, Oslo Rift, Norway.Mineralogical Magazine, Vol. 68, 4, Aug. 1, pp. 687-697.Europe, NorwayAlkaline rocks, mineralogy
DS200512-0937
2004
Makino, K.Satoh, H., Yamaguchi, Y., Makino, K.Ti substitution mechanism in plutonic oxy-kaesutite from the Larvik alkaline complex, Oslo Rift, Norway.Mineralogical Magazine, Vol. 68, 4, Aug. 1,pp. 687-697.Europe, NorwayPetrology - alkaline
DS201906-1315
2019
Makino, Y.Litasov, K.D., Kagi, H., Voropaev, S.A., Hirata, T., Ohfuji, H., Ishibashi., Makino, Y., Bekker, T.B., Sevastyanov, V.S., Afanasiev,V.P., Pokhilenko, N.P.Comparison of enigmatic diamonds from the Tolbachik arc volcano ( Kamchatka) and Tibetan ophiolites: assessing the role of contamination by synthetic materials. Gondwana Research, in press available 38p.Russia, Asia, Tibetdeposit - Tolbachik

Abstract: The enigmatic appearance of cuboctahedral diamonds in ophiolitic and arc volcanic rocks with morphology and infrared characteristics similar to synthetic diamonds that were grown from metal solvent requires a critical reappraisal. We have studied 15 diamond crystals and fragments from Tolbachik volcano lava flows, using Fourier transform infrared spectrometry (FTIR), transmission electron microscopy (TEM), synchrotron X-ray fluorescence (SRXRF) and laser ablation inductively coupled plasma mass-spectrometry (LA-ICP-MS). FTIR spectra of Tolbachik diamonds correspond to typical type Ib patterns of synthetic diamonds. In TEM films prepared using focused ion beam technique, we find Mn-Ni and Mn-Si inclusions in Tolbachik diamonds. SRXRF spectra indicate the presence of Fe-Ni and Fe-Ni-Mn inclusions with Cr, Ti, Cu, and Zn impurities. LA-ICP-MS data show variable but significantly elevated concentrations of Mn, Fe, Ni, and Cu reaching up to 70?ppm. These transition metal concentration levels are comparable with those determined by LA-ICP-MS for similar diamonds from Tibetan ophiolites. Mn-Ni (+Fe) solvent was widely used to produce industrial synthetic diamonds in the former USSR and Russia with very similar proportions of these metals. Hence, it appears highly probable that the cuboctahedral diamonds recovered from Kamchatka arc volcanic rocks represent contamination and are likely derived from drilling tools or other hard instruments. Kinetic data on diamond dissolution in basaltic magma or in fluid phase demonstrate that diamond does not form under the pressures and temperature conditions prevalent within the magmatic system beneath the modern-day Klyuchevskoy group of arc volcanoes. We also considered reference data for inclusions in ophiolitic diamonds and compared them with the composition of solvent used in industrial diamond synthesis in China. The similar inclusion chemistry close to Ni70Mn25Co5 for ophiolitic and synthetic Chinese diamonds scrutinized here suggests that most diamonds recovered from Tibetan and other ophiolites are not natural but instead have a synthetic origin. In order to mitigate further dubious reports of diamonds from unconventional tectonic settings and source rocks, we propose a set of discrimination criteria to better distinguish natural cuboctahedral diamonds from those produced synthetically in industrial environments and found as contaminants in mantle- and crust-derived rocks.
DS202004-0537
2020
Makino, Y.Tamarova, A.P., Marchenko, E.I., Bobrov, A.V., Eremin, N.N., Zinovera, N.G., Irifune, T., Hirata, T., Makino, Y.Interphase REE partitioning at the boundary between the Earth's transition zone and lower mantle: evidence from experiments and atomistic modeling.Minerals MDPI, Vol. 10, 10030262 14p. PdfMantleREE

Abstract: Trace elements play a significant role in interpretation of different processes in the deep Earth. However, the systematics of interphase rare-earth element (REE) partitioning under the conditions of the uppermost lower mantle are poorly understood. We performed high-pressure experiments to study the phase relations in key solid-phase reactions CaMgSi2O6 = CaSiO3-perovskite + MgSiO3-bridgmanite and (Mg,Fe)2SiO4-ringwoodite = (Mg,Fe)SiO3-bridgmanite + (Mg,Fe)O with addition of 1 wt % of REE oxides. Atomistic modeling was used to obtain more accurate quantitative estimates of the interphase REE partitioning and displayed the ideal model for the high-pressure minerals. HREE (Er, Tm, Yb, and Lu) are mostly accumulated in bridgmanite, while LREE are predominantly redistributed into CaSiO3. On the basis of the results of experiments and atomistic modeling, REE in bridgmanite are clearly divided into two groups (from La to Gd and from Gd to Lu). Interphase REE partition coefficients in solid-state reactions were calculated at 21.5 and 24 GPa for the first time. The new data are applicable for interpretation of the trace-element composition of the lower mantle inclusions in natural diamonds from kimberlite; the experimentally determined effect of pressure on the interphase (bridgmanite/CaSiO3-perovskite) REE partition coefficients can be a potential qualitative geobarometer for mineral inclusions in super-deep diamonds.
DS202102-0202
2021
Makino, Y.Litasov, K.D., Kagi, H., Bekker, T.B., Makino, Y., Hirata, T., Brazhkin, V.V.Why Tolbachik diamonds cannot be natural.The American Mineralogist, Vol. 106. pp. 44-53. pdfRussiadeposit - Kamchatka

Abstract: Taking into account recent publications, we provide additional comprehensive evidence that type Ib cuboctahedral diamonds and some other microcrystalline diamonds from Kamchatka volcanic rocks and alluvial placers cannot be natural and undoubtedly represent synthetic materials, which appear in the natural rocks by anthropogenic contamination. The major arguments provided in favor of the natural origin of those diamonds can be easily disproved. They include the coexistence of diamond and deltalumite from Koryaksky volcano; coexistence with super-reduced corundum and moissanite, Mn-Ni silicide inclusions, F-Cl enrichment and F/Cl ratios, and carbon and nitrogen isotopes in Tolbachik diamonds, as well as microtwinning, Mn-Ni silicides, and other inclusions in microcrystalline diamond aggregates from other Kamchatka placers. We emphasize the importance of careful comparison of unusual minerals found in nature, which include type Ib cuboctahedral diamonds and super-reduced phase assemblages resembling industrial slags, with synthetic analogs. The cavitation model proposed for the origin of Tolbachik diamonds is also unreliable since cavitation has only been shown to cause the formation of nanosized diamonds only.
DS202108-1296
2029
Makino, Y.Litasov, K.D., Kagi, H., Bekker, T.B., Hirata, T., Makino, Y.Cuboctahedral type lb diamonds in ophiolitic chromitites and peridotites: the evidence for anthropogenic contamination.International Journal of High Pressure Research, Vol. 39, 3, pp. 480-488.Mantlediamond morphology

Abstract: Here we present trace element compositions of synthetic diamonds, which show spectacular similarity with the compositions of metallic inclusions in type Ib cuboctahedral diamonds in ophiolitic chromitites and peridotites. The compositions of inclusions in synthetic and ophiolite diamonds closely correspond to Ni:Mn:Co?=?70:25:5 in wt.%, which is the most widely used catalyst for HPHT growth of synthetic diamonds in China. Thus, we claim for thorough reconsideration of diamonds in ophiolitic rocks and emphasize that most of them appear by anthropogenic contamination.
DS201112-0937
2011
Makl, G.Setzer, F., Worgard, L., Wenzel, T., Makl, G.Element mobilization in the Agate Mountain carbonatite complex, NW Namibia.Peralk-Carb 2011, workshop held Tubingen Germany June 16-18, PosterAfrica, NamibiaCarbonatite
DS201910-2277
2019
Makombe, E.K.Kusena, B., Makombe, E.K.Sustainable livelihoods and artisanal mining in Marange, Zimbabwe, 2006-2016.Global Environment, Vol. 12, 2, pp. 354-374.Africa, Zimbabwedeposit - Marange

Abstract: The recent discovery of alluvial diamonds in Marange, Zimbabwe, has rekindled the interest of environmental scholars in critiquing the political economy of artisanal mining. The increasing recurrence of this 'illegal' small-scale mining has partly been attributed to its 'lucrative' nature, but more importantly as a safety net to the deepening crises rooted in the country's adverse economic climate in the period under review. The economic structural adjustments during the 1990s, the hefty off-budget gratuities awarded to restive war veterans in 1997, the country's ill-fated intervention in the DRC war in 1988 and the violent land seizures of the early 2000s have contributed to this prolonged setback. This paper first assesses the sustainability of artisanal mining as a livelihood option mostly for the unemployed. It appears that diamond mining produced positive outcomes for some, but by no means all, artisanal miners who accumulated considerable wealth in cattle and real estate. Others failed to break through altogether, suffering heavy losses, including deaths under mining pits. The paper then explores the effects of artisanal mining on the physical environment, including river denudation and soil erosion, deforestation, creation of wastelands and pollution of water bodies. The overriding argument of this study is that artisanal mining has continued to be a sustainable livelihood avenue in spite of its well-known negative impacts. The study is based on semi-structured interviews conducted between 2015 and 2017 with artisanal miners, security personnel, rural district councillors, environmental authorities and former employees of defunct mining firms in Marange. Other sources of data included community-based organisations and civil society groups, as well as newspapers that reported on the unfolding events in Marange at the time.
DS201312-0432
2013
Makota, F.Izuka, T., Campbell, I.H., Allen, C.M., Gill, J.B., Maruyama, S., Makota, F.Evolution of the African continental crust as recorded by U-Pb, Lu-Hf and O isotopes in detrital zircons from modern rivers.Geochimica et Cosmochimica Acta, Vol. Pp. 96-120.AfricaGeochronology, Comgo, Zambesi, Orange
DS201412-0020
2014
Makovchuk, I.Ashchepkov, I., Remirs, L., Ntaflos, T., Vladykin, N., Logvinova, A., Travin, A., Yudin, D., Karpenko, K., Makovchuk, I., Palessky, S., Salikhov, R.Evolution of mantle column of pipe Sytykanskaya, Yakutia kimberlite.Goldschmidt Conference 2014, 1p. AbstractRussia, YakutiaDeposit - Sytykanskaya
DS201705-0808
2017
Makovchuk, I.Ashchepkov, I., Ntaflos, T., Logvinova, A., Vladykin, N., Ivanov, A., Spetsius, Z., Stegnitsky, Y., Kostrovitsky, S., Salikhov, R., Makovchuk, I., Shmarov, G., Karpenko, M., Downes, H., Madvedev, N.Evolution of the mantle sections beneath the kimberlite pipes example of Yakutia.European Geosciences Union General Assembly 2017, Vienna April 23-28, 1p. 6337 AbstractRussia, YakutiaDeposit - Sytykanskaya, Dalnyaya, Aykhal, Zarya, Komosomolskaya, Zarnitsa, Udachnaya

Abstract: The PTX diagrams for the separate phases in Sytykanskaya (Ashchepkov et al., 2016) Dalnyaya (Ashchepkov et al., 2017), pipes shows that the PK show the relatively simple P-X trends and geotherms and shows more contrast and simple layering. The PK contain most abundant material from the root of the magma generation they are dunitic veins as the magma feeders represented by the megacrysts. New results for the Aykhal, Zarya and Komsomolskaya pipes in Alake field and Zarnitsa and Udachnaya pipes in Daldyn field show that evolution is accompanied by the developing of metasomatites and branching and veining of the wall rock peridotites . In Aykhal pipe in PK the Gar- dunites prevail, the xenoliths from the dark ABK "Rebus" contain Cr-Ti - rich garnets and ilmenites, more abundant compared with the grey carbonited breccia Nearly the same features were found for Yubileinaya pipe. The example of Komsomolskya pipes show that the ABK contain more eclogitic xenolith than PK. The developing of the magma channel shown in satellite Chukukskaya and Structurnaya pipe was followed by the separation of some parts of the magmatic feeders and crystallization of abundant Gar megacrysts near o the walls blocking the peridotites from the magma feeder. This drastically decrease diamond grade of pipes. Such blocking seems to be the common features for the latest breccias. In Zarnitsa pipe, the dark PK and ABK also contain fresh xenoliths but not only dunites but also sheared and metasomatic varieties and eclogites. Most of dark ABK in Yakutia contain the intergrowth of ilmenites with brown Ti- Cpx showing joint evolution trends. The late breccia contains completely altered peridotite xenoliths mainly of dunite- harzburgite type. The comparison of the trace elements of the coexisting minerals in megacryst show that they were derived from the protokimberlites but are not in complete equilibrium as well as other megacrystalline phases. Ilmenites show inflections of the trace element patterns of most Ilmenites but more regular for the Cpx and Garnets revealing the sub parallel patterns elevating LREE with the rising TRE. But commonly these are not continuous sequances because they developed in the pulsing moving systems like beneath Zarnitsa. The minerals from the feeders like dunites also show the inflected or S-type REE patterns. From the earlier to later phases the TRE compositions became more evolved reflecting the evolution of protokimberlites. The wall rocks also often show the interaction with the more evolved melts and sometimes "cut" spectrums due to the dissolution some phases and repeated melting events So we could suggest the joint evolution of the mantle column protokimberlites and megacrysts composition and type of kimberlites with the diamond grade. The mantle lithospheric base captured by the PK. The developing and rising protokimbelrites was followed by the crystallization of the diamonds in the gradient in FO2 zone in wall rocks due to reductions of C -bearing fluids and carbonatites (> 1 QMF) on peridotites ((< -2 -5 QMF). The most intensive reactions are near the graphite - diamond boundary where protokimberlites are breaking and where most framesites are forming.
DS200612-0752
2006
Makovchuk, I.V.Kurszlaukis, S., Mahotkin,I., Rotman, A.Y.,Kolesnikov, G.V., Makovchuk, I.V.Syn and post eruptive volcanic processes in the Yubileinaya kimberlite pipe, Yakutia,Emplacement Workshop held September, 5p. extended abstractRussia, YakutiaDeposit - Yubileinya , petrology
DS200912-0417
2009
Makovchuk, I.V.Kurszlaukis, S., Mahotkin, I., Rotman, A.Y., Kolesnikov, G.W., Makovchuk, I.V.Syn and post eruptive volcanic processes in the Yubileinaya kimberlite pipe, Yakutia, Russia and implications for the emplacement of South African style kimberliteLithos, In press available, 36p.Russia, YakutiaDeposit - Yubileinaya
DS201012-0237
2010
Makovchuk, I.V.Gladkov, A.S., Makovchuk, I.V., Lunina, O.V., Bornyakov, S.A., Potekhina, I.A.The Yubieinaya kimberlite pipe site, Russia: 3 D model of the fault block structure.Geology of Ore Deposits, Vol. 52, 3, pp. 234-251.RussiaStructure
DS201212-0036
2013
Makovchuk, I.V.Ashchepkov, I.V., Vladykin, N.V., Ntaflos, T., Downes, H., Mitchell, R., Smelov, A.P., Alymova, N.V., Kostrovitsky, S.I., Rotman, A.Ya., Smarov, G.P., Makovchuk, I.V., Stegnitsky, Yu.B., Nigmatulina, E.N., Khmehnikova, O.S.Regularities and mechanism of formation of the mantle lithosphere structure beneath the Siberian Craton in comparison with other cratons.Gondwana Research, Vol. 23, 1, pp. 4-24.Russia, SiberiaKimberlite pipes
DS201510-1758
2015
Makovchuk, I.V.Ashchepkov, I.V., Logvinova, A.M., Reimers, L.F., Ntaflos, T., Spetisus, Z.V., Vladykin, N.V., Downes, H., Yudin, D.S., Travin, A.V., Makovchuk, I.V., Palesskiy, V.S., KhmelNikova, O.S.The Sytykanskaya kimberlite pipe: evidence from deep seated xenoliths and xenocrysts for the evolution of the mantle beneath Alakit, Yakutia, Russia.Geoscience Frontiers, Vol. 6, 5, pp. 687-714.Russia, YakutiaDeposit - Sytykanskaya

Abstract: Mantle xenoliths (>150) and concentrates from late autolithic breccia and porphyritic kimberlite from the Sytykanskaya pipe of the Alakit field (Yakutia) were analyzed by EPMA and LAM ICP methods. In P-T-X-f(O2) diagrams minerals from xenoliths show widest variations, the trends P-Fe#-CaO, f(O2) for minerals from porphyric kimberlites are more stepped than for xenocrysts from breccia. Ilmenite PTX points mark moving for protokimberlites from the lithosphere base (7.5 GPa) to pyroxenite lens (5-3.5 GPa) accompanied by Cr increase by AFC and creation of two trends P-Fe#Ol ?10-12% and 13-15%. The Opx-Gar-based mantle geotherm in Alakit field is close to 35 mW/m2 at 65 GPa and 600 °C near Moho was determined. The oxidation state for the megacrystalline ilmenites is lower for the metasomatic associations due to reduction of protokimberlites on peridotites than for uncontaminated varieties at the lithosphere base. Highly inclined linear REE patterns with deep HFSE troughs for the parental melts of clinopyroxene and garnet xenocrysts from breccia were influenced by differentiated protokimberlite. Melts for metasomatic xenoliths reveal less inclined slopes without deep troughs in spider diagrams. Garnets reveal S-shaped REE patterns. The clinopyroxenes from graphite bearing Cr-websterites show inclined and inflected in Gd spectrums with LREE variations due to AFC differentiation. Melts for garnets display less inclined patterns and Ba-Sr troughs but enrichment in Nb-Ta-U. The 40Ar/39Ar ages for micas from the Alakit mantle xenoliths for disseminated phlogopites reveal Proterozoic (1154 Ma) age of metasomatism in early Rodinia mantle. Veined glimmerites with richterite - like amphiboles mark ?1015 Ma plume event in Rodinia mantle. The ?600-550 Ma stage manifests final Rodinia break-up. The last 385 Ma metasomatism is protokimberlite-related.
DS201911-2508
2019
Makovchuk, I.V.Ashchepkov, I.V., Mevedev, N.S., Yudin, D.S., Ntaflos, T., Makovchuk, I.V., Ivanov, A.S., Kiseeva, E.Mantle columns beneath Kosomolskaya and Zarnitsa kimberlite pipes: xenolith study.Goldschmidt2019, 1p. AbstractRussiadeposit - Kosomolskaya, Zarnitsa

Abstract: Mantle xenolith from Komsomolskya and Zarnitsa pie were used for the reconstryctions of mantle columns beneath theses kimberlite pipes. Relatively fresh mantle xenolith from Zarnitsa and Komsomolskaya pipes we used for PTX reconstructions of mantle sections. In Zarnitsa dunites - harburgites with richterite, Phl-Ilm veins, sheared lherzolites, pyroxenites (with amphibole) and eclogites and deformed peridotites. Mg -rich Gar and Opx formed stepped P-Fe# trend, Fe- enriched Cpx with Ilm were created mostly by protkimberlites. Sub Ca garnets rarely show U spikes while Ti rich show Th, U, Ta, Nb, Zr and peaks Many minerals demonstrate Th enrichment due to carbonitites. In mantle of Komsomolskaya pipe Phl is wide spreadin periditites from lherzolites ti dunites and in eclogites. There are 6 intervals with sharp division at 5 GPa.Mg eclogites prevae in lower part while fe- enriched in middle part. The Fe# rise is detevcted in lower and upper parts of mantle section. The TRE spiderdiagrams of grnets shows U -pb subduction peaks But Cpx mainly show n Th- peak. The ages of eclogites ogive 500-600 Ma (one 1525 MA) which is much less than in Zarnitsa or Udachnaya having Proterozoic - Archean ages.
DS200912-0661
2009
Makovicky, E.Sand, K.K., Waight, T.E., Pearson, D.G., Nielsen, T.F.D., Makovicky, E., Hutchison, M.T.The lithospheric mantle below southern West Greenland: a geothermobarometric approach to diamond potential and mantle stratigraphy.Lithos, In press availableEurope, GreenlandDiamond prospectivity, geothermometry
DS1970-0325
1971
Makovskaya, N.S.Khar'kiv, A.D., Makovskaya, N.S.Chromium and Titanium in Garnets from Yakutian KimberlitesDoklady Academy of Sciences Nauk SSSR., Vol. 193, PP. 124-126.RussiaBlank
DS1995-0899
1995
MakovskyJuhlin, C., Kashubin, S., Knapp, J.H., Makovsky, RybergProject conducts seismic reflection profiling in the Ural MountainsEos, Vol. 76, No. 19, May 9, p. 193, 197, 198, 199.Russia, UralsTectonics, Geophysics -seismics
DS1960-0373
1963
Makowiecki, L.Z.A.Makowiecki, L.Z.A.Detailed Surveys Were Also Made of a Number of Kimberlite Pipes.Overseas Geol. Min. Res., Vol. 9, No. 1, P.55.Tanzania, East AfricaGeophysics, Kimberlite
DS1860-0211
1873
Makowsky, A.Makowsky, A.Ueber die Diamanten des Kaplandes Auf der Weltaustellung Inwien.Verhand. D. Natur. Vereins In Brunn, Sitzungsberichte., Vol. 12, PP. 16-19.Africa, South Africa, Cape ProvinceGemology
DS201608-1404
2016
Maksimov, A.P.Galimov, E.M., Sevastyanov, V.S., Karpova, G.A., Shilobreeva, S.N., Maksimov, A.P.Microcrystalline diamonds in the oceanic lithosphere and their nature. MicrodiamondsDoklady Earth Sciences, Vol. 469, 1, pp. 670-673.RussiaTolbachik Volcano

Abstract: The carbon isotope composition of microdiamonds found in products of the Tolbachik Volcano eruption, Kamchatka (porous lavas and ash), was studied. The isotope composition of microdiamonds (with an average value of ?13C =-25.05‰) is close to that of microsized carbon particles in lavas (from-28.9 to-25.3‰). The general peculiarities of the diamond-forming environment include (1) no evidence for high pressure in the medium; (2) a reduced environment; and (3) mineralogical evidence for the presence of a fluid. The geochemical data characterizing the type of diamonds studied allow us to suggest that they were formed in accordance with the mechanism of diamond synthesis during cavitation in a rapidly migrating fluid, which was suggested by E.M. Galimov.
DS2001-0721
2001
Maksimov, S.O.Maksimov, S.O., Moiseenko, V.G., Sakho, V.G.High Potassium basalts of eruptive pipes from the eastern part of the Bureya Massif, Russian far east.Doklady Academy of Sciences, Vol. 379A, No. 6, July-August pp. 640-3.Russia, SiberiaPetrology, Bureya Massif
DS200512-0929
2004
Maksimov, S.O.Sakhno, V.G., Maksimov, S.O., Popov, V.K., Sandimirova, G.P.Leucite basanites and potassium shonkinites of the Uglovoe Basin, southern Primorye.Doklady Earth Sciences, Vol. 399A, Nov-Dec. pp. 1322-1326.RussiaBasanites, Foidites
DS200612-0853
2006
Maksimov, S.O.Maksimov, S.O., Popov, V.K.The first finding of carbonatite tuffs in Cenozoic basaltic volcano of southeastern Primorye.Doklady Earth Sciences, Vol. 408, 4, pp. 617-622.RussiaCarbonatite
DS1991-0445
1991
Maksimov, Ye.P.Entin, A.R., Kim, A.AQ., Maksimov, Ye.P., Uyutov, V.I., Tyan, O.A.Apatites from plutonic igneous rocks of the Aldan shieldDoklady Academy of Sciences USSR Earth Sci. Section, Vol. 313, No. 1, pp. 276-279Russia, Aldan shieldCarbonatite
DS200612-0252
2006
Maksimova, T.G.Chukikova, N.A., Maksimova, T.G.Isostatic equilibrium of the Earth's crust and upper mantle.Moscow University Physics Bulletin, Vol. 60, 5, pp. 76-85.MantleGeophysics
DS201905-1058
2019
Makuuskina, A.Makuuskina, A., Tauzin, B., Tkalcic, H., Thybo, H.The mantle transition zone in Fennoscandia: enigmatic high topography without deep mantle thermal anomaly.Geophysical Research Letters, Vol. 46, 7, pp. 3652-3662.Mantlegeothermometry

Abstract: High mountains in Norway have long puzzled scientists because it is challenging to explain their existence. Numerous explanations have been proposed including processes deep inside the Earth. Our results show that these processes must be located above 410?km depth. This observation is critical for the ongoing debate on the cause of the enigmatic mountains in Scandinavia. New data acquired between 2012 and 2017 by the collaborative ScanArray project between European institutions allow mapping of the mantle transition zone—the deepest layer possibly involved in the mountain support. We show that the mantle transition zone boundaries beneath Fennoscandia are close to reference depths and the zone has a standard thickness. As the depths to these boundaries are sensitive to temperatures, this indicates that the mantle transition zone in this area is unaffected by any ongoing deep process. Therefore, the explanation for the high topography in Norway must be found above the mantle transition zone. This study provides the first map of the mantle transition zone below Fennoscandia, which will be valuable for any further global studies of the mantle transition zone.
DS200612-1106
2006
Malakhova, F.Posukhova, T.V., Malakhova, F., Dorokhova, G.I.X ray computer microtomography - effective method of the investigation of the inclusion in diamond.International Mineralogical Association 19th. General Meeting, held Kobe, Japan July 23-28 2006, Abstract p.TechnologyDiamond inclusions
DS201012-0247
2010
Malanin, Yu.A.Grakhanov, S.A., Malanin, Yu.A., Pavlov, Afanasev, Pokhilenko, Gerasimchuk, LipashovaRhaetian diamond placers in Siberia.Russian Geology and Geophysics, Vol. 51, pp. 127-135.Russia, Yakutia, SakhaAlluvials
DS1985-0534
1985
Malanina, R.V.Plotnikova, S.P., Dudenov, YU.A., Malanina, R.V., Kulakov, V.M.The internal structure and properties of a variety of diamond of cubichabit.(Russian)Kristallografiya, (Russian), Vol. 30, No. 6, pp. 1140-1144RussiaDiamond Luminescence, Diamond Morphology
DS200812-0408
2008
Malarkey, J.Gibson, S.A., Malarkey, J., Day, J.A.Melt depletion and enrichment beneath the western Kaapvaal Craton: evidence from Finsch peridotite xenoliths.Journal of Petrology, Vol. 49, 10, pp. 1817-1852.Africa, South AfricaDeposit - Finsch
DS200812-0704
2008
Malarkey, J.Malarkey, J., Pearson, D.G., Davidson, J.P., Wiitig, N.Origins of Cr diopside in peridotite xenoliths.Goldschmidt Conference 2008, Abstract p.A588.Europe, Greenland, Africa, South AfricaDeposit - Kimberley
DS200812-0705
2008
Malarkey, J.Malarkey, J., Pearson, D.J., Nowell, G.M., Davidson, J.P., Ottley, C.J., Kjarsgaard, B., Mitchell, R.H., Kopylova, M.Constraining the crust and mantle contributions to kimberlite - a multi phase micro sampling approach.9IKC.com, 3p. extended abstractCanada, OntarioDeposit - C 14 perovskite crystals
DS200912-0467
2009
Malarkey, J.Malarkey, J., Pearson, D.G., Davidson, J.P., Nowell, G.M., Kjarsgaard, B., Ottley, C.J.Geochemical dissection of a kimberlite: What makes up a whole rock analysis?Goldschmidt Conference 2009, p. A820 Abstract.Canada, Nunavut, Somerset IslandDeposit - Jos
DS200912-0468
2009
Malarkey, J.Malarkey, J., Pearson, D.G., Davidson, J.P., Nowell, G.M., Kjarsgaard, B., Ottley, C.J.Geochemical discretion of a kimberlite: what makes a whole rock analysis?GAC/MAC/AGU Meeting held May 23-27 Toronto, Abstract onlyTechnologyGeochronology
DS200912-0491
2009
Malarkey, J.McNeill, J.C., Klein-BenDavid, O., Pearson, D.G., Nowell, D.G., Ottley, C.J., Chinn, I., Malarkey, J.Quantitative analysis of trace element impurity levels in some gem-quality diamonds.GAC/MAC/AGU Meeting held May 23-27 Toronto, Abstract onlyTechnologyDiamond inclusions
DS201012-0469
2010
Malarkey, J.Malarkey, J., Pearson, D.G., Kjarsgaard, B.A., Davidson, J.P., Nowell, G.M., Ottley, C.J., Stammer, J.From source to crust: tracing magmatic evolution in a kimberlite and a melilitite using microsample geochemistry.Earth and Planetary Science Letters, Vol. 299, 1-2, Oct. 15, pp. 80-90.Canada, Northwest Territories, Africa, South AfricaGeochemistry - JOS
DS201112-0633
2011
Malarkey, J.Malarkey, J., Wittig, N., Pearson, D.G., Davidson, J.P.Characterising modal metasomatic processes in young continental lithospheric mantle: a microsampling isotopic and trace element study on xenoliths from the Middle Atlas Mountains, Morocco.Contributions to Mineralogy and Petrology, Vol. 162, 2, pp. 289-302.Europe, Africa, MoroccoMetasomatism
DS201112-0634
2011
Malarkey, J.Malarkey, J., Wittig, N., Pearson, D.G., Davidson, J.P.Characterising modal metasomatic processes in young continental lithospheric mantle: a microsampling isotopic and trace element study on xenoliths ...Contributions to Mineralogy and Petrology, in press, availableAfrica, MoroccoMetasomatism - Middle Atlas Mountains
DS200612-0854
2006
Malaspina, N.Malaspina, N., Hermann, J., Scambelluri, M., Compagnoni, R.Multistage metasomatism in ultrahigh pressure mafic rocks from North Dabie complex (China).Lithos, Vol.90, 1-2, August pp. 19-42.ChinaUHP - metasomatism
DS200612-1231
2006
Malaspina, N.Scambelluri, M., Hermann, J., Malaspina, N.The deep subduction fluids in high and ultrahigh pressure rocks and their interaction with the overlying mantle wedge.Geochimica et Cosmochimica Acta, Vol. 70, 18, p. 559, abstract only.MantleUHP, subduction
DS200712-0674
2006
Malaspina, N.Malaspina, N., Hermann, J., Scambelluri, M., Compagnoni, R.Polyphase inclusions in garnet orthopyroxenite (Dabie Shan, China) as monitors for metasomatism and fluid related trace element transfer in subduction zone.Geochimica et Cosmochimica Acta, In press availableChinaPeridotite, Maowu ultramafic complex, metasomatism
DS200912-0469
2009
Malaspina, N.Malaspina, N., Poli, S., Fumagalli, P.The oxidation state of metasomatized mantle wedge: insights from COH-bearing garnet peridotite.Journal of Petrology, Vol. 50, 8, pp. 1533-1552.MantleMetasomatism
DS201112-0635
2010
Malaspina, N.Malaspina, N., Scambelluri, M., Poli, S., Van Roermund, H.L.M., Langenhorst, F.The oxidation state of mantle wedge majoritic garnet websterites metasomatised by C-bearing subduction fluids.Earth and Planetary Science Letters, Vol. 298, 3-4, pp. 417-426.MantleMetasomatism
DS201212-0433
2012
Malaspina, N.Malaspina, N., Langenhorst, F., Fumagalli, P., Tumiati, S., Poli, S.Fe 3+ distribution between garnet and pyroxenes in mantle wedge carbonate bearing garnet peridotites ( Sulu, China) and implications for their oxidation state.Lithos, Vol. 146-147, pp. 11-17.ChinaUHP
DS201212-0434
2012
Malaspina, N.Malaspina, N., Langenhorst, F., Fumagalli, P., Tumiati, S., Poli, S.Fe 3 + distribution between garnet and pyroxenes in mantle wedge carbonate bearing garnet peridotites ( Sulu China) and implications for their oxidation state.Lithos, Vol. 146-147, pp. 11-17.ChinaUHP
DS201212-0435
2012
Malaspina, N.Malaspina, N., Langenhorst, F., Poli, S.C-O-H metasomatism and redox processes in the mantle at subduction zones.emc2012 @ uni-frankfurt.de, 1p. AbstractChinaSulu area
DS201212-0436
2012
Malaspina, N.Malaspina, N., Tumiati, S.The role of C-O-H and oxygen fugacity in subduction-zone garnet peridotites.European Journal of Mineralogy, Vol. 24, 4, pp. 607-618.MantleSubduction
DS201312-0569
2013
Malaspina, N.Malaspina, N., Langenhorst, F.Fluid induced redox processes at the slab mantle interface: insights from ultrahigh pressure garnet peridotites.Goldschmidt 2013, AbstractMantleRedox
DS201711-2504
2017
Malaspina, N.Campione, M., Tumiati, S., Malaspina, N.Primary spinel + chlorite inclusions in mantle garnet formed at ultrahigh pressure. Maowu ultramafic complex.Geochemical Perspectives Letters, Vol. 4, pp. 19-23.ChinaUHP

Abstract: Multiphase inclusions represent microenvironments where the interaction between fluid and host mineral is preserved during the rock geological path. Under its peculiar chemical-physical constraints, the entrapped solute-rich fluid might follow a crystallisation mechanism which is not predictable through simple equilibrium arguments. In this letter, by the modelling of solid-solution equilibrium and the application of principles of mass conservation, we demonstrate that cavities in mantle garnet filled with slab-derived fluids can re-equilibrate to a pyrope + spinel + chlorite assemblage at the same high P-T of their formation. The basis of this occurrence is a dissolution-reprecipitation mechanism, triggered by a dilute, non-equilibrated slab fluid.
DS201811-2614
2018
Malaspina, N.Tumiati, S., Malaspina, N.Redox processes and the role of carbon-bearing volatiles from the slab-mantle interface to the mantle wedge. COH system, carbonatiteJournal of the Geological Society, doi.org/10.1144/jgs20`8-046 10p.Mantlemetasomatism

Abstract: The valence of carbon is governed by the oxidation state of the host system. The subducted oceanic lithosphere contains considerable amounts of iron so that Fe3+/Fe2+ equilibria in mineral assemblages are able to buffer the (intensive) fO2 and the valence of carbon. Alternatively, carbon itself can be a carrier of (extensive) ‘excess oxygen’ when transferred from the slab to the mantle, prompting the oxidation of the sub-arc mantle. Therefore, the correct use of intensive and extensive variables to define the slab-to-mantle oxidation by C-bearing fluids is of primary importance when considering different fluid/rock ratios. Fluid-mediated processes at the slab-mantle interface can also be investigated experimentally. The presence of CO2 (or CH4 at highly reduced conditions) in aqueous COH fluids in peridotitic systems affects the positions of carbonation or decarbonation reactions and of the solidus. Some methods to produce and analyse COH fluid-saturated experiments in model systems are introduced, together with the measurement of experimental COH fluids composition in terms of volatiles and dissolved solutes. The role of COH fluids in the stability of hydrous and carbonate minerals is discussed comparing experimental results with thermodynamic models and the message of nature. The investigation of redox processes and the role of volatiles especially at the slab-mantle interface are crucial for depicting the framework of Earth carbon cycling. During the early stages of the Earth's history, the abundances of carbon and other volatiles in the different reservoirs were determined by the coupled evolution of the terrestrial magma ocean and the primitive atmosphere (Hier-Majumder & Hirschmann 2017). Since the Archean, the efficient deep subduction of organic carbon produced by photosynthesis could have promoted carbon burial in the mantle and an increase of atmospheric levels of oxygen through time (Duncan & Dasgupta 2017). In this picture the oxidation state of the mantle, mainly governed by Fe0 and Fe2+/Fe3+ ratios, and its dynamics played a key role in modulating the fO2 of the Earth's surface, leading to the precipitation of minerals in their oxidized forms such as carbonates (Sverjensky & Lee 2010; Andrault et al. 2018). Carbon at the modern terrestrial surface is largely divided between carbonates and organic deposits, with a total budget of 1?×?1023 g C, corresponding to about 100 ppm in the upper mantle (Porcelli & Pepin 2014). Recent estimates from volcanic degassing suggest that the carbon content in the modern deep mantle is even higher (c. 263 ppm; Anderson & Poland 2017; Barry 2017). In fact, the fate of carbonates and organic carbon in modern subduction zones is still largely unconstrained, although recent studies suggest that most of the subducted carbon, in the form of carbonates and organic matter, could be recycled back to the surface (Kelemen & Manning 2015). In this contribution we aim to introduce some basic principles regarding the importance of the use of intensive and extensive variables to define the ‘oxidation transfer’ from the slab to the overlying mantle by C-bearing fluids, and the buffering capacity of the mantle in the carbon speciation at subduction zones, both from the natural and experimental point of view.
DS201904-0789
2018
Malaspina, N.Tumiati, S., Malaspina, N.Redox processes and role of carbon-bearing volatiles from the slab-mantle interface to the mantle wedge.Journal of the Geological Society of London, Vol. 176, pp. 388-397.Mantlecarbon

Abstract: The valence of carbon is governed by the oxidation state of the host system. The subducted oceanic lithosphere contains considerable amounts of iron so that Fe3+/Fe2+ equilibria in mineral assemblages are able to buffer the fO2 and the valence of carbon. Alternatively, carbon itself can be a carrier of redox budget when transferred from the slab to the mantle, prompting the oxidation of the sub-arc mantle. Also, the oxidation of sedimentary carbonaceous matter to CO2 in the slab could consume the available redox budget. Therefore, the correct use of intensive and extensive variables to define the slab-to-mantle redox budget by C-bearing fluids is of primary importance when considering different fluid/rock ratios. Fluid-mediated processes at the slab-mantle interface can be investigated also experimentally. The presence of CO2 (or CH4 at highly reduced conditions) in aqueous COH fluids in peridotitic systems affects the positions of carbonation/decarbonation reactions and of the solidus. Some methods to produce and analyse COH fluid-saturated experiments in model systems are introduced, together with the measurement of experimental COH fluids composition in terms of volatiles and dissolved solutes. The role of COH fluids in the stability of hydrous and carbonate minerals is discussed comparing experimental results with thermodynamic models.
DS200612-1352
2005
Malathi, M.N.Srikantappa, C., Fareeduddin, Malathi, M.N.Olivine hosted melt inclusions and serpentine hosted aqueous fluids in diamond bearing kimberlites from Wajakarur, Andhra Pradesh, India.Geological Society of India, Bangalore November Meeting Group Discussion on Kimberlites and Related Rocks India, Abstract p. 75-76.India, Andhra Pradesh, Dharwar CratonDiamond inclusions
DS1995-1150
1995
Malave, G.Malave, G., Suarez, G.Intermediate depth seismicity in northern Colombia and western Venezuela and its relationship to Caribean plate subductionTectonics, Vol. 14, No. 3, June pp. 617-628ColombiaSubduction, Lithosphere slab
DS1993-0962
1993
Malaveille, J.Malaveille, J.Late Orogenic extension in mountain belts: insights from the Basin and Range and the Late Paleozoic Variscan beltTectonics, Vol. 12, No. 5, October pp. 1115-1130Basin and Range, CordilleraTectonics, Variscan Belt
DS201904-0757
2019
Malavergegne, V.Malavergegne, V., Bureau, H., Raepsaet, C., Gaillard, C., Poncet, F., Surble, M., Sifre, S., Shcheka, D., Fourdrin, S., Deldicque, C., Khodja, D., HichamExperimental constraints on the fate of H and C during planetary core-mantle differentiation. Implications for the Earth.Icarus - New York, Vol. 321, 1, pp. 473-485.Mantlecarbon

Abstract: Hydrogen (H) and carbon (C) have probably been delivered to the Earth mainly during accretion processes at High Temperature (HT) and High Pressure (HP) and at variable redox conditions. We performed HP (1-15?GPa) and HT (1600-2300°C) experiments, combined with state-of-the-art analytical techniques to better understand the behavior of H and C during planetary differentiation processes. We show that increasing pressure makes H slightly siderophile and slightly decreases the highly siderophile nature of C. This implies that the capacity of a growing core to retain significant amounts of H or C is mainly controlled by the size of the planet: small planetary bodies may retain C in their cores while H may have rather been lost in space; larger bodies may store both H and C in their cores. During the Earth's differentiation, both C and H might be sequestrated in the core. However, the H content of the core would remain one or two orders of magnitude lower than that of C since the (H/C)core ratio might range between 0.04 and 0.27.
DS1995-1151
1995
Malavergne, V.Malavergne, V., Guyot, F., Peyronneau, J., Poirier, J-P.Distribution du fer, cobalt, nickel, entre mineraux du manteau inferieurterrestre haute pressure/temperatureCompte Rendus Sci. Paris., (in French), Vol. 320, II a, pp. 455-462.MantlePerovskite, Microscopy
DS200512-0982
2005
Malavergne, V.Siebert, J., Guyot, F., Malavergne, V.Diamond formation in metal? carbonate interactions.Earth and Planetary Science Letters, Vol. 229, 3-4, pp. 205-216.UHP, Earth differentiation, diamond genesis
DS202112-1954
2021
Malaviarachchi, S.P.K.Wang, J., Su, B-X., Ferrero, S., Malaviarachchi, S.P.K., Sakyi, P.A., Yang, Y-H., Dharmapriya, P.L.Crustal derivation of the ca 475 Ma Eppawala carbonatites in Sri Lanka.Journal of Petrology, Vol. 62, 11, pp.1-18. pdfAsia, Sri Lankacarbonatite

Abstract: Although a mantle origin of carbonatites has long been advocated, a few carbonatite bodies with crustal fingerprints have been identified. The Eppawala carbonatites in Sri Lanka are more similar to orogenic carbonatites than those formed in stable cratons and within plate rifts. They occur within the Pan-African orogenic belt and have a formation age of ca. 475 Ma newly obtained in this study with no contemporary mantle-related magmatism. These carbonatites have higher (87Sr/86Sr)i ratios (0•70479-0•70524) and more enriched Nd and Hf isotopic compositions than carbonatites reported in other parts of the world. Model ages (1•3-2•0 Ga) of both Nd and Hf isotopes [apatite ?Nd(t)?=??9•2 to ?4•7; rutile ?Hf(t)?=??22•0 to ?8•02] are in the age range of metamorphic basement in Sri Lanka, and the carbon and oxygen isotopic compositions (?13CPDB?=??2•36 to ?1•71; ?18OSMOW?=?13•91-15•13) lie between those of mantle-derived carbonatites and marble. These crustal signatures are compatible with the chemistry of accessory minerals in the carbonatites, such as Ni-free olivine and Al- and Cr-poor rutile. Modeling results demonstrate that the Eppawala carbonatite magmas originated from a mixture of basement gneisses and marbles, probably during regional metamorphism. This interpretation is supported by the occurrence of the carbonatites along, or near, the axes of synforms and antiforms where granitic gneiss and marble are exposed. Therefore, we propose that the Eppawala carbonatites constitute another rare example of a carbonatitic magma that was derived from melting of a sedimentary carbonate protolith. Our findings suggest that other orogenic carbonatites with similar features should be re-examined to re-evaluate their origin.
DS1984-0238
1984
Malaysheva, T.V.Dmitriev, L.V., Sobolev, A.V., Uchanov, A.V., Malaysheva, T.V.Primary Differences in Oxygen Fugacity and Depth of Melting in the Mantle Source Regions for Oceanic Basalts.Earth Plan. Sci. Letters, Vol. 70, PP. 303-310.GlobalMineral Chemistry, Mid Ocean Ridge Basalt (morb)
DS201212-0437
2012
Malbam, B.Malbam, B.Mineral chemistry of peridotites fom the Naga ophiolite belt, northeastern India and their petrological significance.10th. International Kimberlite Conference Held Bangalore India Feb. 6-11, Poster abstractIndiaOphiolites
DS1859-0069
1840
Malcomson, J.G.Malcomson, J.G.On the Fossils of the Eastern Portion of the Great Basaltic district of India.Transactions Geological Society of London., SER. 2, Vol. 5, PP. 537-575. REVIEW: Journal of SOC. ARTS, Nov. 2India, Andhra Pradesh, MadrasRegional Geology, Stratigraphy, Alluvial Diamond Placers, Kistn
DS1950-0182
1954
Malde, H.E.Malde, H.E.Serpentine Pipes at Garnet Ridge, ArizonaScience., Vol. 119, P. 618.United States, Arizona, Colorado Plateau, Rocky MountainsDiatreme
DS1960-0374
1963
Malde, H.E.Malde, H.E., Thaden, R.E.Serpentine at Garnet RidgeIn: Geology And Uranium-vanadium Deposits of The Monument Va, No. 1103, PP. 54-61.United States, Arizona, Colorado Plateau, Rocky MountainsDiatreme
DS202010-1868
2020
Maldonado, A.Presser, J.L.B., Monteiro, M., Maldonado, A.Impact diamonds in an extravagant metal piece found in Paraguay. *** PORTHistoria Natural *** english abstract, Vol. 10, 2, 12p. PdfSouth America, Paraguaymeteorite

Abstract: Around 70 km SSE of Chovoreca Hill (Paraguay), a pitcher-like metal piece weighing approximately 303 kg was found. Several studies have been carried out on this piece. Metallographic examination resembles cast iron that presents eutectoid microtextures, but the metal showed Neumann lines. Small fragments of the piece were diluted in concentrated HCl and with this it was possible to obtain colorless crystals, with size ranging from 10 ?m to 1 mm, approximately; SEM/EDS studies showed that major element present is carbon which suggests the presence of diamonds. Raman spectroscopy proved that crystals are diamonds, that showing bands in the “lonsdaleite/diamond zone”, further, the results also showed bands that accuse that the carbon of the diamonds are of meteoritic origin. From the calculus of the FWHM with values around to 42-373 cm-1 centered on 1282 cm-1 peak could be an indication of a very powerful impact that would have formed the diamonds.
DS200612-0855
2006
Male, S.K.Male, S.K., Nol, E.Impacts of roads associated with the Ekati diamond mine, Northwest Territories, Canada, on reproductive success and breeding habitat of Lapland Longspurs.Canadian Journal of Zoology, Vol. 83, 10, pp. 1286-1296.Canada, Northwest TerritoriesBiology
DS201503-0166
2015
Malec, J.Pasava, J., Malec, J., Griffin, W.L., Gonzalez-Jiminez, J.M.Re-Os isotopic constraints on the source of platinum-group minerals (PGMs) from the Vestrev pyrope rich garnet placer deposit, Bohemian Massif.Ore Geology Reviews, Vol. 68, pp. 117-1326EuropeGarnet mineralogy
DS201608-1420
2016
Malecka, A.Malecka, A.The great Mughal and the Orlov: one and the same diamond? 189.62 caratsJournal of Gemmology, Vol. 35, 1, pp. 56-63.TechnologyDiamonds notable
DS201804-0718
2017
Malecka, A.Malecka, A.Naming of the Koh-i-Noor and the origin of Mughal-cut diamonds.Journal of Gemmology, Vol. 35, 8, pp. 738-751.Indiadiamonds notable - Koh-i-Noor

Abstract: For centuries, the Koh-i-Noor, or Mountain of Light, has been a diamond of exceptional renown in the East as well as in the West. Several legends circulate regarding this stone, and among these are tales of its origin and the way it received its name. This article attempts to verify the authenticity of these accounts and shows that the true origin of the diamond's name is connected to its appearance achieved through the faceting style known today as the Mughal cut. Although the provenance of this cut has thus far not been determined, this article proposes that it possibly originated in the 16th century in Goa, India, through the Gujaratis and under the influence of European diamond cutters. Various lines of evidence suggest that the Koh-i-Noor may have been worked in the 16th century by an Indian specialist in the Vijayanagara Empire.
DS201806-1208
2018
Malehmir, A.Andersson, M., Malehmir, A.Internal architecture of the Alno alkaline and carbonatite complex (central Sweden) revealed using 3D models of gravity and magnetic data.Tectonophysics, Vol. 740-741, pp. 53-71.Europe, Swedencarbonatite - Alno
DS201907-1561
2019
Malehmir, A.Mattsson, H.B., Hogdahl, K., Carlsson, M., Malehmir, A.The role of mafic dykes in the petrogenesis of the Archean Siilinjarvi carbonatite complex, east central Finland.Lithos, in press available, 37p.Europe, Finlandcarbonatites

Abstract: The Archean (~2.6?Ga) Siilinjärvi carbonatite complex in east-central Finland is crosscut by a few ultramafic lamprophyre dykes, together with a broad array of more evolved mafic dykes that range in composition from foidites to various types of alkali basalts. A possible genetic link between the primitive lamprophyres and the carbonatite complex has previously been hypothesised, but their exact relations have been unclear due to the regional metamorphic overprint (i.e., greenschist facies). Here we focus on the petrology and petrography of the mafic dykes, and integrate the data to present a coherent model that can explain the genesis of the Siilinjärvi carbonatite complex. Field-relations, in combination with petrography and geochemistry, indicate that there are at least three generations of mafic dykes present. The oldest dykes (Generation I) are strongly deformed, and inferred to have been emplaced shortly after the formation of the complex itself. These dykes can be divided into two groups (i.e., ultramafic lamprophyres and Group A), where Group A comprises foidites characterised by low SiO2 (41.4-51.5?wt%) and high alkali (>10?wt% K2O) content. We interpret the foiditic magmas to have evolved from primitive ultramafic lamprophyres by fractionating a clinopyroxene-olivine dominated mineral assemblage that was devoid of feldspar. This fractionation path forced alkali-enrichment in the magmas belonging to Group A, which pushed them into the miscibility gap, and resulted in liquid immiscibility that produced moderately alkaline conjugate carbonatite(s). Subsequent fractionation of the conjugate carbonatite by predominantly calcite and apatite produced the mineralogically homogeneous carbonatite cumulate that is exposed at Siilinjärvi. Younger, less deformed, mafic dykes (belonging to Generations II and III) exhibit trace element characteristics, broadly similar to basaltic dyke swarms in the region. The younger dykes are characterised by the presence of large plagioclase crystals in thin sections. Crystallisation of a feldspar-bearing mineral assemblage resulted in only moderate enrichment of alkalis with increased fractionation, which caused the younger dykes to evolve along the more common basalt-to-trachyte series. Thus, the magmas belonging to Generations II and III at Siilinjärvi never fulfilled the conditions required to produce carbonatites by liquid immiscibility.
DS202111-1768
2021
Malek, M.A.Gong, Z., Evans, D.A.D., Youbi, N., Lahna, A.A., Sodelund, U., Malek, M.A., Wen, B., Jing, X., Ding, J., Boumedhdi, M.A., Ernst, R.E.Reorienting the West African craton in Paleoproterozoic-Msoproterozoic supercontinent Nuna.Geology, Vol. 49, 10, pp. 1171-1176. pdfAfrica, west AfricaNuna

Abstract: The location of the West African craton (WAC) has been poorly constrained in the Paleoproterozoic-Mesoproterozoic supercontinent Nuna (also known as Columbia). Previous Nuna reconstruction models suggested that the WAC was connected to Amazonia in a way similar to their relative position in Gondwana. By an integrated paleomagnetic and geochronological study of the Proterozoic mafic dikes in the Anti-Atlas Belt, Morocco, we provide two reliable paleomagnetic poles to test this connection. Incorporating our new poles with quality-filtered poles from the neighboring cratons of the WAC, we propose an inverted WAC-Amazonia connection, with the northern WAC attached to northeastern Amazonia, as well as a refined configuration of Nuna. Global large igneous province records also conform to our new reconstruction. The inverted WAC-Amazonia connection suggests a substantial change in their relative orientation from Nuna to Gondwana, providing an additional example of large-magnitude cumulative azimuthal rotations between adjacent continental blocks over supercontinental cycles.
DS202106-0937
2021
Maleke, M.Gomez-Arias, A., Yesares, L., Carabello, M.A., Maleke, M., Vermeulen, D., Nieto, J.M., van Heerden, E., Castillo, J.Environmental and geochemical characterization of alkaline mine wastes from Phalaborwa ( Palabora) complex, South Africa.Journal of Geochemical Exploration, Vol. 224, 106757, 13p. PdfAfrica, South Africadeposit - Palabora

Abstract: A detailed characterization of alkaline tailing ponds and waste rock dumps from Phalaborwa Igneous Complex (PIC) South Africa, has been accomplished. The study goes beyond the environmental characterization of mining wastes, offering the first insight towards the recycling of the wastes as alkaline reagent to neutralize acid industrial wastewater. To achieve these aims, tailings and waste rocks were characterized using a combination of conventional, novel and modified Acid Rock Drainage (ARD) prediction methodologies, as well as South African leachate tests, sequential extractions and pseudo-total digestions. The scarcity of Fe-sulphide minerals and the abundance of alkaline minerals indicated that PIC wastes are not ARD producers. The highest neutralization potential was found in the carbonatite rocks and East tailing samples (range between 289 and 801 kg CaCO3 eq/t). According to the National Environmental Management Waste Act (59/2008) of South Africa, tailing ponds and waste rock dumps from PIC classify as non-hazardous (Type 3 waste). The sequential extractions showed that the different fractions from most of the samples would mostly release sulphate and non-toxic elements, such as Ca, Mg, Na and K, which might be a concern if leached in high concentration. In addition, relatively high concentrations of radionuclides, such as U and Th (average of 6.7 and 36.3 mg/kg, respectively) are present in the non-labile fraction of PIC wastes, while the leachable concentrations were always below 0.006 mg/L. Among PIC wastes, East tailing would be the best option as alkaline reagent to neutralize acid wastewater because of its high neutralization potential and non-harmful leachate composition. In general, this study exposes the shortcomings in mine waste characterization, particularly for alkaline mine wastes, and introduces the assessment of potential revalorization as a novel practice in mine waste characterization that, if extended as a regular practice, would facilitate a circular economy approach to the mining industry with its consequent economic and environmental benefits.
DS1970-0555
1972
Males, P.A.Males, P.A.Diamond Crystals from the Isabella River, New South WalesAustralian Gemologist., Nov. PP. 23-25.AustraliaKimberlite, Oberon District
DS1992-0568
1992
Malesieux, J-M.Gillet, P., Fiquet, G., Malesieux, J-M., Geiger, C.A.high pressure and high temperature Raman spectroscopy of end membergarnets: pyrope, grossular and andraditeEuropean Journal of Mineralogy, Vol. 4, No. 4, pp. 651-664GlobalMineralogy, Garnets
DS1997-1149
1997
Malevsky, A.V.Ten, A., Yuen, D.A., Malevsky, A.V.Fractal features in mixing of non-Newtonian and Newtonian mantleconvection.Earth and Planetary Letters, Vol. 146, No. 3/4. Feb 1, pp. 401-414.MantleMixing models
DS2001-0722
2001
Malevsky-Malevich, S.P.Malevsky-Malevich, S.P., Molkentin, NadyozhinaNumerical simulation of permafrost parameters distribution in RussiaCold Regions Science and Tech., Vol. 32, No. 1, pp. 1-11.RussiaPermafrost, climate change - not specific to diamonds
DS1992-0569
1992
Malezieux, J.M.Gillet, P., Fiquet, G., Malezieux, J.M., Geiger, C.A.high pressure and high temperature Raman spectroscopy of end-member garnets-pyrope, grossular and andraditeEuropean Journal of Mineralogy, Vol. 4, No. 4, July-August pp. 651-664GlobalMineralogy, Garnets
DS200412-0207
2004
Malferrari, D.Brigatti, M.R., Malferrari, D., Medici, L., Ottolini, L., Poppi, L.Crystal chemistry of apatites from the Tapira carbonatite complex, Brazil.European Journal of Mineralogy, Vol. 16, 4,pp. 677-685.South America, BrazilMineral chemistry
DS201012-0020
2009
MalginaAshchepkov, Vladykin, Pokhilenko, Logvinova, Kuligin, Pokhilenko, Malgina, Alymova, Mityukhin, KopylovaApplication of the monomineral thermobarometers for the reconstruction of the mantle lithosphere structure.Deep Seated Magmatism, its sources and plumes, Ed. Vladykin, N.V., p. 98-116.MantleGeothermometry
DS1993-0271
1993
MalhburgCoira, B., Malhburg, Kay, S., Viramonte, J.Upper Cenozoic magmatic evolution of the Argentine Puma - a model for changing subduction geometryInternational Geology Review, Vol. 35, No. 8, August pp. 677-720Peru, Bolivia, CHileAltiplano, Tectonics
DS1991-0277
1991
Malhburg Kay, S.Coira, B., Malhburg Kay, S.Mantle and crustal components in high K to shoshonitic series volcanic rocks in the eastern Argentine PunaEos, Spring Meeting Program And Abstracts, Vol. 72, No. 17, April 23, p. 295ArgentinaShoshonites, Mantle
DS1991-1039
1991
Malhotra, D.Malhotra, D., Klimpel, R.R., Mular, A.L.Evaluation and optimization of metallurgical performanceAmerican Institute of Mining, Metallurgical, and Petroleum Engineers (AIME), 365p. $ 38.50GlobalMining -plant evaluation, Metallurgy
DS1995-1152
1995
MaliMaliAshton signs up for Mali ventureAustralian Financial Review, June 14.AustraliaNews item, Ashton Mining
DS200812-0706
2008
Mali, B.M.Mali, B.M., Pendey, G.P., Candrakala, K., Reddy, P.R.Imprints of a Proterozoic tectonothermal anomaly below the 1.1 Ga kimberlitic province of southwest Cuddapah Basin, Dharwar craton, southern India.Geophysical Journal International, Vol. 172, 1, pp. 422-438.IndiaGeothermometry
DS1994-0998
1994
Malich, K.N.Lazarenko, V.G., Malich, K.N.Platinum group element distribution in meymechites of the Maymecha-Kotuyprovince.Doklady Academy of Sciences Acad. Science USSR, Vol. 323, No. 2, June pp. 185-188.RussiaMeimechitites
DS201512-1938
2015
Malich, K.N.Malich, K.N., Khiller, V.V., Badanina, I.Yu., Belousova, E.A.Results of dating of thorianite and badeleyite from carbonatites of the Guli massif, Russia.Doklady Earth Sciences, Vol. 464, 2, pp. 1029-1032.RussiaCarbonatite

Abstract: The isotopic -geochronological features of thorianite and baddeleyite from carbonatites of the Guli massif, located within Maimecha -Kotui province in the north of the Siberian Platform, are characterized for the first time. The economic complex platinum-group element (PGE) and gold placer deposits are closely related to the Guli massif. Similar geochronological data for thorianite (250.1 ± 2.9 Ma, MSWD = 0.09, n = 36) and baddeleyite (250.8 ± 1.2 Ma, MSWD = 0.2, n = 6) obtained by two different methods indicate that carbonatites were formed close to the Permian -Triassic boundary and are synchronous with tholeiitic flood basalts of the Siberian Platform.
DS201801-0036
2017
Malierova, P.Malierova, P., Schulmann, K., Gerya, T.Relamination styles in collisional orogens.Tectonics, in press availableMantlesubduction

Abstract: During continental collision, a part of the lower-plate material can be subducted, emplaced at the base of the upper plate, and eventually incorporated into its crust. This mechanism of continental-crust transformation is called relamination and it has been invoked to explain occurrences of high-pressure felsic rocks in different structural positions of several orogenic systems. In the present study we reproduced relamination during continental collision in a thermo-mechanical numerical model. We performed a parametric study and distinguished three main types of evolution regarding the fate of the subducted continental crust: (i) return along the plate interface in a subduction channel or wedge, (ii) flow at the bottom of the upper-plate lithosphere and subsequent trans-lithospheric exhumation near the arc or in the back-arc region ("sub-lithospheric relamination"), and (iii) nearly horizontal flow directly into the upper-plate crust ("intra-crustal relamination"). Sub-lithospheric relamination is preferred for relatively quick convergence of thin continental plates. An important factor for the development of sub-lithospheric relamination is melting of the subducted material, which weakens the lithosphere and opens a path for the exhumation of the relaminant. In contrast, a thick and strong overriding plate typically leads to exhumation near the plate interface. If the overriding plate is too thin or weak, intra-crustal relamination occurs. We show that each of these evolution types has its counterpart in nature: (i) the Alps and the Caledonides, (ii) the Himalayan-Tibetan system and the European Variscides, and (iii) pre-Cambrian ultra-hot orogens.
DS201012-0041
2010
Malikwisha, M.Bauer, F.U., Glasmacher, U.A., Malikwisha, M., Mambo, V.S., Mutete, B.V.The eastern Congo - a beauty spot, rediscovered from a geological point of view.Geology Today, Vol. 26, 2, pp. 55-64.Africa, Democratic Republic of CongoHistory
DS1986-0902
1986
Malinconico, M.L.Zimmerman, J., Malinconico, M.L.Finite strain in the Missouri Mountain Formation (Silurian)south central Benton uplift, ArkansawGeological Society of America, Vol. 18, No. 3, p. 273. AbstractMidcontinent, ArkansasTectonics
DS1993-0963
1993
Maling, D.H.Maling, D.H.Coordinate systems and map projectionsPergamon Press, 500p. $ 50.00 softcoverGlobalBook -ad, Cartography
DS1995-1021
1995
Malinin, S.D.Kravchuk, I.F., Ivanova, G.F., Malinin, S.D.rare earth elements (REE) fractionation in acid fluid magma systemsGeochemistry International, Vol. 32, No. 11, Nov. 1, pp. 60-68RussiaMagma, Rare earths
DS1982-0386
1982
Malinko, S.V.Malinko, S.V., Ilupin, I.P., Berman, I.B., Stoliarova, A.N.Boron in Kimberlites of the Kuoika Field According to the Dat a of Local Radioagraphic Analysis.Doklady Academy of Sciences AKAD. NAUK SSSR., Vol. 265, No. 1, PP. 170-172.RussiaSpectrometry, Boron
DS1983-0430
1983
Malinovskii, I.I.Malinovskii, I.I., Doroshev, A.M., Kalinin, A.A.Investigation of the Stability of Pyrope-grossular Garnets Under the Pressure of 30kbar.Doklady Academy of Sciences AKAD. NAUK SSSR., Vol. 268, No. 1, PP. 163-168.RussiaBlank
DS1989-0052
1989
Malinovskii, I.Yu.Babich, Yu.V., Doroshev, A.M., Malinovskii, I.Yu.Heat-activated transformation of coesite at standard pressureSoviet Geology and Geophysics, Vol. 30, No. 2, pp. 140-146RussiaCoesite, Mineralogy
DS1992-1159
1992
Malinovskiy, I.Yu.Palyanov, Yu.N., Malinovskiy, I.Yu., Borzdov, Yu.M., KhokhryakovUse of the split sphere apparatus for growing large diamond crystals without the use of a hydraulic press.Doklady Academy of Sciences USSR, Earth Science Section, Vol. 315, pp. 233-237.RussiaDiamond synthesis
DS1980-0296
1980
Malinovskiy, YU.A.Rumyantsev, G.S., Nedezhdina, YE. D., Malinovskiy, YU.A.Lonsdaleite-containing Polycrystalline DiamondsTsnigri, No. 153, PP. 3-19.RussiaBlank
DS200412-1209
2004
Malitch, K.N.Malitch, K.N.Osmium isotope constraints on contrasting sources and prolonged melting in the Proterozoic upper mantle: evidence from ophiolitiChemical Geology, Vol. 208, 1-4, pp. 157-173.Russia, Taimyr, Kunar, Austria, Alps, KraubathGeochronology, platinum, PGE, alloys, depletion
DS201012-0733
2009
Malitch, K.N.Sobolev, A.V., Sobolev, S.V., Kuzmin, D.V., Malitch, K.N., Petrunin, A.G.Siberian meimechites: origin and relation to flood basalts and kimberlites.Russian Geology and Geophysics, Vol. 50, 12, pp. 999-1033.Russia, SiberiaMeimechite
DS201112-0636
2011
Malitch, K.N.Malitch, K.N., Karpisky, A.P., Sorokhtina, N.V., Goncharov, M.M.Carbonatite of the Guli massif as a possible source of gold: evidence from zirconolite inclusions in Au rich nuggets.Peralk-Carb 2011... workshop June 16-18, Tubingen, Germany, Abstract p.147-150.Russia, SiberiaGuli
DS201112-0637
2011
Malitch, K.N.Malitch, K.N., Karpisky, A.P., Sorokhtina, N.V., Goncharov, M.M.Carbonatite of the Guli massif as a possible source of gold: evidence from zirconolite inclusions in Au rich nuggets.Peralk-Carb 2011... workshop June 16-18, Tubingen, Germany, Abstract p.147-150.Russia, SiberiaGuli
DS201112-0638
2011
Malitch, K.N.Malitch, K.N., Sorokhtina, N.V., Goncharov, N.N., Goncharov, M.M.Carbonatite of the Guli Massif as a possible source of gold: evidence from zirconolite inclusions in au-rich nuggets.Peralk-Carb 2011, workshop held Tubingen Germany June 16-18, PosterRussia, SiberiaCarbonatite
DS2001-1028
2001
MalitestaSchingaro, E., Scaordani, Malitesta, Rudolf, LouetteXPS investigation on natural Ti bearing garnetsPlinius, No. 24, p. 195. abstractGlobalMineralogy - garnet
DS1994-1093
1994
Malkov, A.B.Malkov, A.B.Genesis of curved faced diamonds of the Timan region and the UralsDoklady Academy of Sciences, Vol. 325, No. 4, pp. 158-161.Russia, Urals, Yakutia, Brazil, NamibiaDiamond morphology, Alluvials
DS1975-0329
1976
Malkov, B.A.Malkov, B.A.Tectonic Patterns in the Localization of Kimberlite ProvinceDoklady Academy of Science USSR, Earth Science Section., Vol. 203, No. 1-6. PP. 46-48.South Africa, RussiaTectonics
DS1975-0330
1976
Malkov, B.A.Malkov, B.A., Gustomesov, V.A.Jurassic Fossils in Kimberlite of the Olenek Uplift and Age of Kimberlite Volcanism in the Northeastern Part of the Siberian PlatformDoklady Academy of Science USSR, Earth Science Section., Vol. 229, No. 1-6, PP. 67-69.RussiaKimberlite
DS1975-0558
1977
Malkov, B.A.Malkov, B.A.Epitaxial Intergrowths As Indicator of Thermodynamic Conditions of Diamond Formation.Akad. Nauk Sssr Izv. Ser. Geol., Vol. 1977, No. 5, PP. 84-95.RussiaKimberlite
DS1975-1026
1979
Malkov, B.A.Garanin, V.K., Kudryavtseva, G.P., Malkov, B.A.Mantle Inclusions in Diatremes of the Northeastern Party Of the Russian PlatformDoklady Academy of Science USSR, Earth Science Section., Vol. 249, No. 1-6, PP. 140-143.RussiaPetrography
DS1975-1125
1979
Malkov, B.A.Malkov, B.A., Askhabov, A.M.External (pseudo) Symmetry of Diamond Crystals; a Morphologic Consequence of Their Recrystallization in the Mantle.Doklady Academy of Science USSR, Earth Science Section., Vol. 249, No. 1-6, PP. 129-131.RussiaDiamond Morphology
DS1981-0279
1981
Malkov, B.A.Malkov, B.A., Askhabov, A.M.Nitrogen Segregations (platelets) in Diamond Crystals Produced by Diamond Annealing in the Mantle.Doklday Academy of Science Ussr Earth Sci. Section., Vol. 248, No. 1, PP. 179-181.RussiaBlank
DS1982-0075
1982
Malkov, B.A.Askhabov, A.M., Malkov, B.A.The Origin of Natural Coated Diamond CrystalsDoklady Academy of Science USSR, Earth Science Section., Vol. 251, No. 4, PP. 130-132.RussiaCrystallography
DS1982-0387
1982
Malkov, B.A.Malkov, B.A.Diamond Bearing Mantle - a Product of the Earth's Early Evolution.Doklady Academy of Science USSR, Earth Science Section., Vol. 252, No. 1-6, PP. 40-41.RussiaXenoliths, Genesis, Kimberlite, Thermometry
DS1982-0438
1982
Malkov, B.A.Milanovskiy, YE.YE., Malkov, B.A.Epochs of Kimberlite Volcanism and Global Compressive and Expansionary Cycles of the Earth.Doklady Academy of Science USSR, Earth Science Section., Vol. 252, No. 5, PP. 62-65.Russia, Global, United States, Colorado, Wyoming, South Africa, Canada, West AfricaTectonics, Structure, Geochronology
DS1983-0452
1983
Malkov, B.A.Milanovskii, E.E., Malkov, B.A.Archean Diamond Bearing Mantle in the Expanding Earth ModelDoklady Academy of Sciences AKAD NAUK SSSR., Vol. 269, No. 2, PP. 430-434.RussiaGenesis
DS1983-0453
1983
Malkov, B.A.Milanovskiy, YE.YE., Malkov, B.A.Diamond bearing Archean mantle in a model of an expansionistearth.(Russian)Doklady Academy of Sciences Akademy Nauk SSSR, (Russian), Vol. 269, No. 2, pp. 430-434RussiaDiamond Genesis
DS1984-0474
1984
Malkov, B.A.Malkov, B.A.Archean diamond bearing mantle and kimberlite volcanism in the expanding earth theory.(Russian)In: Problemy Rasshirenya i Pulsatsiy Zemli., (Russian) ed., Izd. Nauka Moscow, pp. 56-61RussiaMantle
DS1984-0475
1984
Malkov, B.A.Malkov, B.A., Milanovskiy, Y.Y., Kropotkin, P.N., Pushcharovski.Archean Diamond Bearing Mantle and Kimberlite Volcanism in The Expanding Earth Theory.Izd. Nauka, Moscow., PP. 56061.RussiaIgneous Rocks, Kimberlite, Genesis, Plate Tectonics
DS1984-0519
1984
Malkov, B.A.Milanovskiy, YE.YE., Malkov, B.A.The Archean Diamond Bearing Mantle in the Model of the Expanding Earth.Doklady Academy of Science USSR, Earth Science Section., Vol. 269, No. 1-6, SEPTEMBER PP. 48-52.RussiaGenesis
DS1994-1094
1994
Malkov, B.A.Malkov, B.A.Cosmic cycles of a kimberlitic volcanism.(Russian)Doklady Academy of Sciences Nauk., (Russian), Vol. 338, 4, Oct. pp. 798-801.RussiaPetrology, Kimberlite
DS1995-1153
1995
Malkov, B.A.Malkov, B.A., Holopova, E.B.Epochs and cycles of diamond genesis in cratons and mobile beltsProceedings of the Sixth International Kimberlite Conference Abstracts, pp. 345-347.RussiaTectonic cycles, Diamond genesis
DS1996-0875
1996
Malkov, B.A.Malkov, B.A.Cosmic cyles of kimberlite volcanismDoklady Academy of Sciences, Vol. 340, No. 2, March., pp. 134-137.RussiaKimberlite volcanism., Earth Moon system
DS1998-0925
1998
Malkov, B.A.Malkov, B.A.The cosmic cycles of kimberlite volcanism: new data7th International Kimberlite Conference Abstract, pp. 537-9.Russia, Siberia, AustraliaTectogenesis, homological rows, CTC - cosmic cyles of tectogenesis
DS1998-0926
1998
Malkov, B.A.Malkov, B.A., Malyshev, N.A.Diamond occurrences in kimberlites and lamproites from Phanerozoic mobile belts an example of Timans, Urals..7th International Kimberlite Conference Abstract, pp. 540-2.Arkansas, Louisiana, Russia, Urals, ChinaMobile belts, Diatremes - rybalites
DS1982-0236
1982
Malkov, Y.V.Gurvich, M.Y., Kozlov, A.A., Malkov, Y.V., Pavlov, Y.G., Semonov.Structures of disintegration in rutile of kimberlite in Letseng la Teraipipe, Lesotho.(Russian)Geochemistry International (Geokhimiya), (Russian), No. 10, pp. 1520-1523LesothoBlank
DS1975-1123
1979
Mal'kov, B.A.Mal'kov, B.A.Radiologic Proof of the Xenogenic Origin of Olivine, Pyrope and Chromium Diopside 'phenocrysts' in Kimberlite.Doklady Academy of Sciences USSR, EARTH SCI. SECTION., Vol. 245, No. 1-6, PP. 151-153.RussiaBlank
DS1975-1124
1979
Mal'kov, B.A.Mal'kov, B.A., et al.Radiologic Proof of the Xenogenic Origin of Olivine Pyrope And Chrome-diopside "phenocryts" in Kimberlite.Doklady Academy of Science USSR, Earth Science Section., Vol. 245, No. 1-6, PP. 151-153.RussiaBlank
DS1981-0278
1981
Mal'kov, B.A.Mal'kov, B.A.Global Epochs of Kimberlite Volcanism in the PhanerozoicDoklady Academy of Science USSR, Earth Science Section., Vol. 242, No. 5, PP. 113-115.RussiaKimberlite
DS1998-1325
1998
MalkovetsSharygin, V.V., Golovin, A.V., Smirnov, S.Z., MalkovetsRelationships between websterite xenolith and host basanite ( Pipe BeleKhakasia, Russia)... silicate melt7th International Kimberlite Conference Abstract, pp. 788-790.RussiaXenolith, Deposit - Bele pipe
DS200512-0007
2004
MalkovetsAgashev, A.M., Pokhilenko, N.P., Tolstov, A.V., Polyanichko, Malkovets, SobolevNew age dat a on kimberlites from the Yakutian Diamondiferous Province.Doklady Earth Sciences, Vol. 399, 8, pp.1142-1145.Russia, YakutiaGeochronology
DS1997-0542
1997
Malkovets, V.Ionov, D., Griffin, W.L., O'Reilly, S.Y., Malkovets, V.Carbonate bearing mantle xenoliths in alkali basalts: phase mineral compositions, MetasomatismGeological Association of Canada (GAC) Abstracts, AustraliaXenoliths, Mantle carbonate Metasomatism
DS200812-0946
2008
Malkovets, V.Reguir, E., Chakhmouradian, A., Halden, N., Malkovets, V., Yang, P.Major and trace element compositional variation of phlogopite from kimberlites and carbonatites as a petrogenetic indicator.9IKC.com, 3p. extended abstractCanada, AfricaGeochemistry - ferromagnesian micas
DS201012-0234
2010
Malkovets, V.Gibsher, A., Malkovets, V., Travin, A.New Ar Ar dat a of the lamprophyric dykes of west Sangilen ( southeast Tuva south Russia): the oldest mantle xenoliths bearing basaltic hosts.International Dyke Conference Held Feb. 6, India, 1p. AbstractRussia, TuvaGeochronology
DS201012-0470
2010
Malkovets, V.Malkovets, V., Griffin, W., Poikhilenko, N., O'Reilly, S., Mishenin, S.Thickness of diamond bearing metasomatic aureoles in the cratonic SCLM.Goldschmidt 2010 abstracts, PosterMantleDiamond genesis
DS201312-0336
2013
Malkovets, V.Griffin, W.L., Belousova, E.A., O'Neill, C., O'Reilly, S.Y., Malkovets, V., Pearson, N.J., Spetsius, S., Wilde, S.A.The world turns over: Hadean-Archean crust mantle evolution.Lithos, Vol. 189, pp. 2-15.MantleCrust- mantle review
DS201412-0543
2014
Malkovets, V.Malkovets, V.Mineralogy and geochemistry of megacrystalline pyrope peridotites from the Udachnaya pipe, Siberian craton.ima2014.co.za, AbstractRussia, YakutiaDeposit - Udachnaya
DS201607-1361
2016
Malkovets, V.Malkovets, V.Timing of the Siberian craton kimberlite magmatism: evidences from the U-Pb dating of kimberlitic zircon.IGC 35th., Session A Dynamic Earth 1p. AbstractRussiaKimberlite
DS202010-1840
2020
Malkovets, V.Dymshits, A., Sharygin, I., Malkovets, V., Yakovlev, I.V., Gibsher, A.A., Alifirova, T.A., Vorobei, S.S., Potapov, S.V., Garanin, V.K.Thermal state, thickness and composition of the lithospheric mantle beneath the Upper Muna kimberlite field, Siberian Craton, constrained by clinopyroxene xenocrysts and comparison with Daldyn and Mirny fields.Minerals, 10.1039/DOJA00308E 20p. PdfRussiadeposit - Muna

Abstract: To gain better insight into the thermal state and composition of the lithospheric mantle beneath the Upper Muna kimberlite field (Siberian craton), a suite of 323 clinopyroxene xenocrysts and 10 mantle xenoliths from the Komsomolskaya-Magnitnaya (KM) pipe have been studied. We selected 188 clinopyroxene grains suitable for precise pressure (P)-temperature (T) estimation using single-clinopyroxene thermobarometry. The majority of P-T points lie along a narrow, elongated field in P-T space with a cluster of high-T and high-P points above 1300 °C, which deviates from the main P-T trend. The latter points may record a thermal event associated with kimberlite magmatism (a “stepped” or “kinked” geotherm). In order to eliminate these factors, the steady-state mantle paleogeotherm for the KM pipe at the time of initiation of kimberlite magmatism (Late Devonian-Early Carboniferous) was constrained by numerical fitting of P-T points below T = 1200 °C. The obtained mantle paleogeotherm is similar to the one from the nearby Novinka pipe, corresponding to a ~34-35 mW/m2 surface heat flux, 225-230 km lithospheric thickness, and 110-120 thick "diamond window" for the Upper Muna field. Coarse peridotite xenoliths are consistent in their P-T estimates with the steady-state mantle paleogeotherm derived from clinopyroxene xenocrysts, whereas porphyroclastic ones plot within the cluster of high-T and high-P clinopyroxene xenocrysts. Discrimination using Cr2O3 demonstrates that peridotitic clinopyroxene xenocrysts are prevalent (89%) among all studied 323 xenocrysts, suggesting that the Upper Muna mantle is predominantly composed of peridotites. Clinopyroxene-poor or -free peridotitic rocks such as harzburgites and dunites may be evident at depths of 140-180 km in the Upper Muna mantle. Judging solely from the thermal considerations and the thickness of the lithosphere, the KM and Novinka pipes should have excellent diamond potential. However, all pipes in the Upper Muna field have low diamond grades (<0.9, in carats/ton), although the lithosphere thickness is almost similar to the values obtained for the high-grade Udachnaya and Mir pipes from the Daldyn and Mirny fields, respectively. Therefore, other factors have affected the diamond grade of the Upper Muna kimberlite field.
DS202010-1841
2020
Malkovets, V.Dymshits, A., Sharygin, I., Liu, Z., Korolev, N., Malkovets, V., Alifirova, T., Yakovlev, I., Xu, Y-G.Oxidation state of the lithospheric mantle beneath Komosomolskaya-Magnitnaya kimberlite pipe, Upper Muna field, Siberian craton.Minerals, Vol. 10, 9, 740 10.3390/ min10090740 24p. PdfRussiadeposit - Muna

Abstract: The oxidation state of the mantle plays an important role in many chemical and physical processes, including magma genesis, the speciation of volatiles, metasomatism and the evolution of the Earth’s atmosphere. We report the first data on the redox state of the subcontinental lithospheric mantle (SCLM) beneath the Komsomolskaya-Magnitnaya kimberlite pipe (KM), Upper Muna field, central Siberian craton. The oxygen fugacity of the KM peridotites ranges from ?2.6 to 0.3 logarithmic units relative to the fayalite-magnetite-quartz buffer (?logfO2 (FMQ)) at depths of 120-220 km. The enriched KM peridotites are more oxidized (?1.0-0.3 ?logfO2 (FMQ)) than the depleted ones (from ?1.4 to ?2.6 ?logfO2 (FMQ)). The oxygen fugacity of some enriched samples may reflect equilibrium with carbonate or carbonate-bearing melts at depths >170 km. A comparison of well-studied coeval Udachnaya and KM peridotites revealed similar redox conditions in the SCLM of the Siberian craton beneath these pipes. Nevertheless, Udachnaya peridotites show wider variations in oxygen fugacity (?4.95-0.23 ?logfO2 (FMQ)). This indicates the presence of more reduced mantle domains in the Udachnaya SCLM. In turn, the established difference in the redox conditions is a good explanation for the lower amounts of resorbed diamonds in the Udachnaya pipe (12%) in comparison with the KM kimberlites (33%). The obtained results advocate a lateral heterogeneity in the oxidation state of the Siberian SCLM.
DS1995-0064
1995
Malkovets, V.G.Ashchepkov, I.V., Litasov, A.L., Malkovets, V.G.Origin and evolution of mantle melts beneath Vitim PlateauProceedings of the Sixth International Kimberlite Conference Extended Abstracts, p. 17-19.Russia, VitiM.Xenoliths, Picrite, basanite, diapir
DS1995-0065
1995
Malkovets, V.G.Ashchepkov, I.V., Malkovets, V.G., Litasov, K.D.Stratification of upper mantle columns beneath the Vitim Plateau in Miocene and Quaternary.Proceedings of the Sixth International Kimberlite Conference Extended Abstracts, p. 20-22Russia, VitiM.Xenoliths, Picrite, basanite, diapir
DS1998-0927
1998
Malkovets, V.G.Malkovets, V.G., Ionov, D.A., Griffin, W.L., O'ReillyA P-T composition cross section of spinel and garnet facies lithospheric mantle in the Minusa region.7th International Kimberlite Conference Abstract, pp. 543-5.Russia, SiberiaCraton -basanite, Deposit - Minusa region
DS2000-0344
2000
Malkovets, V.G.Golovin, A.V., Sharygin, V.V., Malkovets, V.G.Evolution of melt during crystallization of the Bele pipe basanites. North Minusa depression.Russian Geology and Geophysics, Vol.41,12,pp.1710-31., Vol.41,12,pp.1710-31.RussiaBasanite
DS2000-0345
2000
Malkovets, V.G.Golovin, A.V., Sharygin, V.V., Malkovets, V.G.Evolution of melt during crystallization of the Bele pipe basanites. North Minusa depression.Russian Geology and Geophysics, Vol.41,12,pp.1710-31., Vol.41,12,pp.1710-31.RussiaBasanite
DS2000-0578
2000
Malkovets, V.G.Litasov, K.D., Mekhonoshin, A.S., Malkovets, V.G.Mineralogy of mantle xenoliths from Pliocene basanites of Dzhilinda River.Vitim volcanic field.Russian Geology and Geophysics, Vol.41,11,pp.1477-1501., Vol.41,11,pp.1477-1501.RussiaXenoliths, Basanites
DS2000-0579
2000
Malkovets, V.G.Litasov, K.D., Mekhonoshin, A.S., Malkovets, V.G.Mineralogy of mantle xenoliths from Pliocene basanites of Dzhilinda River.Vitim volcanic field.Russian Geology and Geophysics, Vol.41,11,pp.1477-1501., Vol.41,11,pp.1477-1501.RussiaXenoliths, Basanites
DS2000-0580
2000
Malkovets, V.G.Litasov, K.D., Mekhonoshin, A.S., Malkovets, V.G.Geochemistry of clinopyroxenes and petrogenesis of mantle xenoliths from Pliocene basanites.. Vitim field.Russian Geology and Geophysics, Vol.41,11,pp.1502-19., Vol.41,11,pp.1502-19.RussiaXenoliths, Geochemistry
DS2000-0581
2000
Malkovets, V.G.Litasov, K.D., Mekhonoshin, A.S., Malkovets, V.G.Geochemistry of clinopyroxenes and petrogenesis of mantle xenoliths from Pliocene basanites.. Vitim field.Russian Geology and Geophysics, Vol.41,11,pp.1502-19., Vol.41,11,pp.1502-19.RussiaXenoliths, Geochemistry
DS2002-0591
2002
Malkovets, V.G.Golovin, A.V., Sharygin, V.V., Pokhilenko, N.P., Malkovets, V.G., KoelsovSecondary melt inclusions in olivine from unaltered kimberlites of the Udachnaya East pipe, Yakutia.Doklady Earth Sciences, Vol. 388,1,pp. 93-96.Russia, YakutiaPetrology, deposit - Udachnaya
DS2003-0478
2003
Malkovets, V.G.Golovin, A.V., Sharygin, V.V., Pkhilenko, N.P., Malkovets, V.G., Kolesov, B.A.Secondary melt inclusions in olivine from unaltered kimberlites of the Udachnaya EastDoklady Earth Sciences, Russia, YakutiaBlank
DS2003-0479
2003
Malkovets, V.G.Golovin, A.V., Sharygin, V.V., Pokhilenko, N.P., Malkovets, V.G., KolesavSecondary melt inclusions in olivine from unaltered kimberlites of the Udachnaya EastDoklady Earth Sciences, Vol. 388,1, pp. 93-96.Russia, YakutiaInclusions, Deposit - Udachnaya
DS2003-0480
2003
Malkovets, V.G.Golovin, A.V., Sharygin, V.V., Pokhilenko, N.P., Malkovets, V.G., Sobolev, N.V.Secondary melt inclusions in olivine from unaltered kimberlites of the Udachnaya8 Ikc Www.venuewest.com/8ikc/program.htm, Session 7, POSTER abstractRussia, YakutiaDeposit - Udachnaya
DS2003-0739
2003
Malkovets, V.G.Konstantin, D., Litasov, V.G., Malkovets, V.G., Kostrovitsky, S.J., Taylor, L.A.Petrogenesis of ilmenite bearing symplectite xenoliths from Vitim alkaline basalts andInternational Geology Review, Vol. 45, No. 11, Nov. pp. 976-997.RussiaPetrology
DS2003-0757
2003
Malkovets, V.G.Kuligin, S.S., Malkovets, V.G., Pkhilenko, N.P., Vavilov, M.A., Griffin, W.L.Mineralogical and geochemical characteristics of a unique mantle xenoliths from the8ikc, Www.venuewest.com/8ikc/program.htm, Session 4, POSTER abstractRussia, YakutiaMantle geochemistry, Deposit - Udachnaya
DS2003-0825
2003
Malkovets, V.G.Litasov, K.D., Litasov, Y.D., Malkovets, V.G., Taniguchi, H.Lithosphere structure and thermal regime of the upper mantle beneath the Baikal region:8 Ikc Www.venuewest.com/8ikc/program.htm, Session 9, POSTER abstractRussiaBlank
DS2003-0868
2003
Malkovets, V.G.Malkovets, V.G., Litasov, Y.D., Travin, A.V., Litasov, K.D., Taylor, L.A.Volcanic pipes as clues to upper mantle petrogenesis: Mesozoic Ar Ar dating of theInternational Geology Review, Vol. 45, 2, pp. 133-142.Russia, SiberiaPipe - models
DS2003-0869
2003
Malkovets, V.G.Malkovets, V.G., Taylor, L.A., Griffin, W., O'Reilly, S., Pearson, N., PokhilenkoCratonic considitons beneath Arkhangelsk, Russia: garnet peridotites form the Grib8ikc, Www.venuewest.com/8ikc/program.htm, Session 4, POSTER abstractRussia, Kola PeninsulaMantle geochemistry, Deposit - Grib
DS2003-0870
2003
Malkovets, V.G.Malkovets, V.G., Taylor, L.A., Griffin, W.L., O'Reilly, S., Pokhilenko, N.P.Eclogites from the Grib kimberlite pipe, Arkangelsk, Russia8ikc, Www.venuewest.com/8ikc/program.htm, Session 2, POSTER abstractRussia, ArkangelskEclogites and Diamonds, Deposit - Grib
DS2003-1092
2003
Malkovets, V.G.Pokhilenko, N.P., Griffin, W.L., Shimizu, N., McLean, R.C., Malkovets, V.G.Pyropes and chromites of the Snap Lake King Lake kimberlite dyke system in relation8 Ikc Www.venuewest.com/8ikc/program.htm, Session 6, POSTER abstractNorthwest TerritoriesDeposit - Snap Lake King Lake
DS2003-1114
2003
Malkovets, V.G.Promprated, P., Taylor, L.A., Floss, C., Malkovets, V.G., Anand, M., GriffinDiamond inclusions from Snap Lake, NWT, Canada8ikc, Www.venuewest.com/8ikc/program.htm, Session 3, POSTER abstractNorthwest TerritoriesDiamonds - inclusions, Deposit - Snap Lake
DS200412-0685
2003
Malkovets, V.G.Golovin, A.V., Sharygin, V.V., Pkhilenko, N.P., Malkovets, V.G., Kolesov, B.A., Sobolev, N.V.Secondary melt inclusions in olivine from unaltered kimberlites of the Udachnaya East pipe, Yakutia.Doklady Earth Sciences, Vol. 388, 1, pp. 93-96.Russia, YakutiaGeochemistry - mineral chemistry
DS200412-0686
2003
Malkovets, V.G.Golovin, A.V., Sharygin, V.V., Pokhilenko, N.P., Malkovets, V.G., Sobolev, N.V.Secondary melt inclusions in olivine from unaltered kimberlites of the Udachnaya eastern pipe, Yakutia.8 IKC Program, Session 7, POSTER abstractRussia, YakutiaKimberlite petrogenesis Deposit - Udachnaya
DS200412-1032
2003
Malkovets, V.G.Konstantin, D., Litasov, V.G., Malkovets, V.G., Kostrovitsky, S.J., Taylor, L.A.Petrogenesis of ilmenite bearing symplectite xenoliths from Vitim alkaline basalts and Yakutian kimberlites, Russia.International Geology Review, Vol. 45, no. 11, Nov. pp. 976-997.RussiaPetrology
DS200412-1048
2004
Malkovets, V.G.Kostrovitsky, S.I., Malkovets, V.G., Verichev, E.M., Garanin, V.K., Suvorova, L.V.Megacrysts from the Grib kimberlite pipe ( Arkandgelsk Province, Russia).Lithos, Vol. 77, 1-4, Sept. pp. 511-523.Russia, Archangel, Kola PeninsulaHigh chromium association, genesis
DS200412-1145
2003
Malkovets, V.G.Litasov, K.D., Litasov, Y.D., Malkovets, V.G., Taniguchi, H.Lithosphere structure and thermal regime of the upper mantle beneath the Baikal region: evidence from deep seated xenoliths.8 IKC Program, Session 9, POSTER abstractRussiaCraton studies
DS200412-1146
2003
Malkovets, V.G.Litasov, K.D., Malkovets, V.G., Kostrovitsky, S.I., Taylor, L.A.Petrogenesis of ilmenite bearing symplectic xenoliths from Vitim alkaline basalts and Yakutian kimberlites, Russia.International Geology Review, Vol. 45, 11, pp. 976-997.Russia, YakutiaXenoliths - petrology
DS200412-1210
2003
Malkovets, V.G.Malkovets, V.G., Litasov, Y.D., Travin, A.V., Litasov, K.D., Taylor, L.A.Volcanic pipes as clues to upper mantle petrogenesis: Mesozoic Ar Ar dating of the Miusinsk basalts, South Siberia.International Geology Review, Vol. 45, 2, pp. 133-142.Russia, SiberiaPipe - models
DS200412-1563
2003
Malkovets, V.G.Pokhilenko, N.P., Griffin, W.L., Shimizu, N., McLean, R.C., Malkovets, V.G., Pokhilenko, L.N., Malygina, E.V.Pyropes and chromites of the Snap Lake King Lake kimberlite dyke system in relation to the problem of the southern Slave Craton8 IKC Program, Session 6, POSTER abstractCanada, Northwest TerritoriesMantle petrology Deposit - Snap Lake King Lake
DS200612-0004
2006
Malkovets, V.G.Agashev, A.M., Pokhilenko, N.P., Malkovets, V.G., Sobolev, N.V.Sm Nd isotopic system in garnet megacrysts from the Udachnaya kimberlite pipe (Yakutia) and petrogenesis of kimberlites.Doklady Earth Sciences, Vol. 407A, 3, pp. 491-494.Russia, YakutiaGeochronology - Udachnaya
DS200712-0675
2007
Malkovets, V.G.Malkovets, V.G., Griffin, W.L., O'Reilly, S.Y., Wood, B.J.Diamond, subcalcic garnet, and mantle metasomatism: kimberlite sampling patterns define the link.Geology, Vol. 35, 4, pp. 339-342.MantleMetasomatism
DS200912-0470
2009
Malkovets, V.G.Malkovets, V.G., Belousova, E.A., Griffin, W.L., Buzlukova, L.V., Shatsky, V.S., O'Reilly, S.Y., Pokhilenko, N.P.U/Pb dating of zircons from the lower crustal xenoliths from Siberian kimberlites.Goldschmidt Conference 2009, p. A823 Abstract.Russia, SiberiaDeposit - Udachnaya
DS200912-0623
2009
Malkovets, V.G.Reguir, E.P., Chakmouradian, A.R., Halden, N.M., Malkovets, V.G., Yang, P.Major and trace element compositional variation of phlogopite from kimberlites and carbonatites as a petrogenetic indicator.Lithos, In press available, 50p.TechnologyGeochemistry - ferromagnesian micas
DS201112-0639
2011
Malkovets, V.G.Malkovets, V.G., Griffin, Pearson, Rezvukhin, O'Reilly, Pokhilenko, Garanin, Spetsius, LitasovLate metasomatic addition of garnet to the SCLM: Os-isotope evidence.Goldschmidt Conference 2011, abstract p.1395.RussiaUdachnaya, Daldyn
DS201112-0640
2011
Malkovets, V.G.Malkovets, V.G., Zedgenizov, Sobolev, Kuzmin, Gibsher, Shchukina, Golovin, Verichev, PokhilenkoContents of trace elements in olivines from diamonds and peridotite xenoliths of the V.Grib kimberlite pipe ( Arkhangel'sk Diamondiferous province, Russia).Doklady Earth Sciences, Vol. 436, 2, pp. 301-307.RussiaDeposit - Grib
DS201112-0945
2011
Malkovets, V.G.Shatsky, V.S., Malkovets, V.G., Buzlukova, L., Griffin, W.L., Belousova, E.A., O'Reilly, S.Y.Deep crust of the Siberian craton evidence from xenolith.Goldschmidt Conference 2011, abstract p.1850.RussiaUdachnaya, Leningradskaya, Yubileynaya
DS201112-0972
2011
Malkovets, V.G.Skublov, S.G., Shchukina, E.V., Guseva, N.S., Malkovets, V.G., Golovin, N.N.Geochemical characteristics of zircons from xenoliths in the V. Grib kimberlite pipe, Archangelsk Diamondiferous province.Geochemistry International, Vol. 49, 4, pp. 415-421.Russia, Kola PeninsulaGeochemistry
DS201212-0010
2012
Malkovets, V.G.Alifirova, T.A., Pokhilenko, L.N., Malkovets, V.G., Griffin, W.L.Petrological inferences for the role of exsolution in upper mantle: evidence from the Yakutian kimberlite xenoliths.10th. International Kimberlite Conference Feb. 6-11, Bangalore India, AbstractRussia, YakutiaPetrology
DS201212-0242
2012
Malkovets, V.G.Gibsher, A.A., Malkovets, V.G., Griffin, W.L., O'Reilly, S.Y.Petrogenesis of composite xenoliths from alkaline basalts ( West Sangilen) Russia10th. International Kimberlite Conference Held Bangalore India Feb. 6-11, Poster abstractRussiaAlkalic
DS201212-0438
2012
Malkovets, V.G.Malkovets, V.G., Griffin, W.L., Pearson, N.J., Rezvukhin, D.I., Oreilly, S.Y., Pokhilenko, N.P., Garanin, V.K., Spetsius, Z.V., Litasov, K.D.Late metasomatic addition of garnet to the SCLM: Os-itope evidence.10th. International Kimberlite Conference Feb. 6-11, Bangalore India, AbstractMantleMetasomatism
DS201212-0439
2012
Malkovets, V.G.Malkovets, V.G., Griffin, W.L., Pokhilenko, N.P., O'Reilly, S.Y., Dak, A.I., Tolstov, A.V., Serov, I.V., Bazhan, I.S., Kuzmin, D.V.Lithosphere mantle structure beneath the Nakyn kimberlite field, Yakutia.10th. International Kimberlite Conference Held Bangalore India Feb. 6-11, Poster abstractRussia, YakutiaDeposit - Nakyn
DS201212-0583
2012
Malkovets, V.G.Rezvukhin, D.I., Malkovets, V.G., Gibsher, A.A., Kuzmin, D.V., Griffin, W.L., Pokhilenko, N.P., O'Reilly, S.Y.Mineral inclusions in pyropes from some kimberlite pipes of Yakutia.10th. International Kimberlite Conference Held Bangalore India Feb. 6-11, Poster abstractRussia, YakutiaDeposit - Internationskaya
DS201212-0642
2012
Malkovets, V.G.Shchukina, E.V., Malkovets, V.G., Golovin, N.N., Pokhilenko, N.P.Peridotitic mantle section beneath V Grib kimberlite pipe ( Arkhangelsk region, Russia): mineralogical composition P-T conditions, metasomatism.10th. International Kimberlite Conference Held Bangalore India Feb. 6-11, Poster abstractRussia, Archangel, Kola PeninsulaDeposit - Grib
DS201212-0643
2012
Malkovets, V.G.Shchulina, E.V., Golovin, N.N., Malkovets, V.G., Pokhilenko, N.P.Mineralogy and equilibrium P-T estimates for peridotite assemblages from the V Grib kimberlite pipe (Arkangelsk kimberlite province).Doklady Earth Sciences, Vol. 444, 2, pp. 776-781.Russia, Kola Peninsula, ArchangelDeposit - Grib
DS201412-0695
2014
Malkovets, V.G.Poikhilenko, N.P., Afanasiev, V.P., Agashev, A.M., Malkovets, V.G., Poikhilenko, L.N.New archean terranes with thick lithosphere of arctic regions of Siberia and North American ancient platforms: are they prospective for Diamondiferous kimberlites?30th. International Conference on Ore Potential of alkaline, kimberlite and carbonatite magmatism. Sept. 29-, Russia, CanadaKimberlite
DS201412-0698
2014
Malkovets, V.G.Pokhilenko, L.N., Malkovets, V.G., Kuzmin, D.V., Pokhilenko, N.P.New dat a on the mineralogy of megacrystalline pyrope peridotite from the Udachnaya kimberlite pipe, Siberian Craton, Yakutian Diamondiferous province.Doklady Earth Sciences, Vol. 454. no. 2, pp. 179-184.Russia, YakutiaDeposit - Udachnaya
DS201605-0887
2016
Malkovets, V.G.Rezvukhin, D.I., Malkovets, V.G., Sharygin, I.S., Kuzmin, D.V., Litasov, K.D., Gibsher, A.A., Pokhilenko, N.P., Sobolev, N.V.Inclusions of Cr- and Cr-Nb-Rutile in pyropes from the Internationalnaya kimberlite pipe, Yakutia.Doklady Earth Sciences, Vol. 466, 2, Feb. pp. 173-176.Russia, YakutiaDeposit - International

Abstract: The results of study of rutile inclusions in pyrope from the Internatsionalnaya kimberlite pipe are presented. Rutile is characterized by unusually high contents of impurities (up to 25 wt %). The presence of Cr2O3 (up to 9.75 wt %) and Nb2O5 (up to 15.57 wt %) are most typical. Rutile inclusions often occur in assemblage with Ti-rich oxides: picroilmenite and crichtonite group minerals. The Cr-pyropes with inclusions of rutile, picroilmenite, and crichtonite group minerals were formed in the lithospheric mantle beneath the Mirnyi field during their joint crystallization from melts enriched in Fe, Ti, and other incompatible elements as a result of metasomatic enrichment of the depleted lithospheric mantle.
DS201605-0888
2016
Malkovets, V.G.Rezvukhin, D.I., Malkovets, V.G., Sharygin, I.S., Kuzmin, D.V., Litasov, K.D., Gibsher, A.A., Pokhilenko, N.P., Sobolev, N.V.Inclusions of crichonite group minerals in pyropes from the Internatsionalnaya kimberlite pipe, Yakutia.Doklady Earth Sciences, Vol. 466, 2, Feb. pp. 206-209.Russia, YakutiaDeposit - International
DS201611-2150
2016
Malkovets, V.G.Ziberna, L., Nimis, P., Kuzmin, D., Malkovets, V.G.Error sources in single clinopyroxene thermobarometry and a mantle geotherm for the Novinka kimberlite, Yakutia. Upper Muna fieldAmerican Mineralogist, Vol. 101, pp. 222-2232.RussiaDeposit - Novinka

Abstract: A new suite of 173 clinopyroxene grains from heavy-mineral concentrates of the diamondiferous Novinka kimberlite (Upper Muna field, Yakutia) has been analyzed for major and minor elements with an electron microprobe to perform a thermobarometric study and model the thermal structure of the Archean Upper Muna lithospheric mantle. Scrupulous evaluation of propagation of analytical uncertainties on pressure estimates revealed that (1) the single-clinopyroxene geobarometer can be very sensitive to analytical uncertainties for particular clinopyroxene compositions, and that (2) most clinopyroxenes from Novinka have compositions that are sensitive to analytical uncertainties, notwithstanding their apparent compositional suitability for single-clinopyroxene thermobarometry based on previously proposed application limits. A test on various mantle clinopyroxenes containing different proportions of the sensitive elements Cr, Na, and Al allowed us to identify clinopyroxene compositions that produce unacceptably high propagated errors and to define appropriate analytical conditions (i.e., higher beam currents and longer counting times for specific elements) that allow precise P-T estimates to be obtained for sensitive compositions. Based on the results of our analytical test, and taking into account the intrinsic limitations of the single-clinopyroxene thermobarometer, we have designed a new protocol for optimum thermobarometry, which uses partly revised compositional filters. The new protocol permits precise computation of the conductive paleogeotherm at Novinka with the single-clinopyroxene thermobarometer of Nimis and Taylor (2000). Thermal modeling of the resulting P-T estimates indicates a ~34 mW/m2 surface heat flow, a thermal lithosphere thickness of ~225 km, and an over 100 km thick “diamond window” beneath Novinka in the middle Paleozoic (344-361 Ma). We estimate that appropriate analytical conditions may extend the applicability of single-clinopyroxene thermobarometry to over 90% of clinopyroxene-bearing garnet peridotites and pyroxenites and to ~70% of chromian-diopside inclusions in diamonds. In all cases, application to clinopyroxenes with Cr/(Cr+Al)mol < 0.1 is not recommended. We confirm the tendency of the single-clinopyroxene barometer to progressively underestimate pressure at P > 4.5 GPa.
DS201612-2320
2016
Malkovets, V.G.Malkovets, V.G., Rezvukhin, D.I., Belousova, E.A., Griffin, W.L., Sharygin, I.S., Tretiakov, I.G., Gibsher, A.A., O'Reilly, S.Y., Kuzmin, D.V., Litasov, K.D., Logvinova, A.M., Pokhilenko, N.P., Sobolev, N.V.Cr-rich rutile: a powerful tool for diamond exploration.Lithos, Vol. 265, pp. 304-311.Russia, SiberiaDeposit - Internationalskaya

Abstract: Mineralogical studies and U-Pb dating have been carried out on rutile included in peridotitic and eclogitic garnets from the Internatsionalnaya pipe, Mirny field, Siberian craton. We also describe a unique peridotitic paragenesis (rutile + forsterite + enstatite + Cr-diopside + Cr-pyrope) preserved in diamond from the Mir pipe, Mirny field. Compositions of rutile from the heavy mineral concentrates of the Internatsionalnaya pipe and rutile inclusions in crustal almandine-rich garnets from the Mayskaya pipe (Nakyn field), as well as from a range of different lithologies, are presented for comparison. Rutile from cratonic mantle peridotites shows characteristic enrichment in Cr, in contrast to lower-Cr rutile from crustal rocks and off-craton mantle. Rutile with Cr2O3 > 1.7 wt% is commonly derived from cratonic mantle, while rutiles with lower Cr2O3 may be both of cratonic and off-cratonic origin. New analytical developments and availability of standards have made rutile accessible to in situ U-Pb dating by laser ablation ICP-MS. A U-Pb age of 369 ± 10 Ma for 9 rutile grains in 6 garnets from the Internatsionalnaya pipe is consistent with the accepted eruption age of the pipe (360 Ma). The equilibrium temperatures of pyropes with rutile inclusions calculated using Ni-in-Gar thermometer range between ~ 725 and 1030 °C, corresponding to a depth range of ca ~ 100-165 km. At the time of entrainment in the kimberlite, garnets with Cr-rich rutile inclusions resided at temperatures well above the closure temperature for Pb in rutile, and thus U-Pb ages on mantle-derived rutile most likely record the emplacement age of the kimberlites. The synthesis of distinctive rutile compositions and U-Pb dating opens new perspectives for using rutile in diamond exploration in cratonic areas.
DS201701-0035
2016
Malkovets, V.G.Tretiakova, I.G., Belousova, E.A., Malkovets, V.G., Griffin, W.L., Piazolo, S., Pearson, N.J., O'Reilly, S.Y., Nishido, H.Recurrent magmatic activity on a lithosphere scale structure: crystallization and deformation in kimberlitic zircons.Gondwana Research, Vol. 42, pp. 126-132.RussiaDeposit - Nubinskaya

Abstract: Kimberlites are not only the most economically important source of diamonds; they also carry unique information encapsulated in rock fragments entrained as the magma traverses the whole thickness of the lithosphere. The Nurbinskaya pipe in the Siberian kimberlite province (Russia) is one of several intruded along the Vilyui Rift, a major terrane boundary. The pipe contains three populations of mantle-derived zircon xenocrysts: Archean (mean age 2709 ± 9 Ma), Devonian (mean age 371 ± 2.3 Ma), and a subset of grains with evidence of brittle deformation and rehealing, and a range of ages between 370 and 450 Ma. The Hf-isotope, O-isotope and trace-element signatures of the last group provide a link between the Archean and Devonian events, indicating at least three episodes of magmatic activity and zircon crystallization in the lithosphere beneath the pipe. The emplacement of the Nurbinskaya pipe ca 370 Ma ago was only the youngest activity in a magma plumbing system that has been periodically reactivated over at least 2.7 billion years, controlled by the lithosphere-scale structure of the Vilyui Rift.
DS201801-0060
2018
Malkovets, V.G.Shatsky, V.S., Malkovets, V.G., Belousova, E.A., Tretiakova, I.G., Griffin, W.L., Ragozin, A.L., Wang, Q., Gibsher, A.A., O'Reilly, S.Y.Multi-stage modification of Paleoarchean crust beneath the Anabar tectonic province ( Siberian craton).Precambrian Research, Vol. 305, pp. 125-144.Russiacraton - Siberian

Abstract: According to present views, the crustal terranes of the Anabar province of the Siberian craton were initially independent blocks, separated from the convecting mantle at 3.1 (Daldyn terrane), 2.9 (Magan terrane) and 2.5?Ga (Markha terrane) (Rosen, 2003, 2004; Rosen et al., 1994, 2005, 2009). Previous studies of zircons in a suite of crustal xenoliths from kimberlite pipes of the Markha terrane concluded that the evolution of the crust of the Markha terrane is very similar to that of the Daldyn terrane. To test this conclusion we present results of U-Pb and Hf-isotope studies on zircons in crustal xenoliths from the Zapolyarnaya kimberlite pipe (Upper Muna kimberlite field), located within the Daldyn terrane, and the Botuobinskaya pipe (Nakyn kimberlite field) in the center of the Markha terrane. The data on xenoliths from the Botuobinskaya kimberlite pipe record tectonothermal events at 2.94, 2.8, 2.7 and 2?Ga. The event at 2?Ga caused Pb loss in zircons from a mafic granulite. U-Pb dating of zircons from the Zapolyarnaya pipe gives an age of 2.7?Ga. All zircons from the studied crustal xenoliths have Archean Hf model ages ranging from 3.65 to 3.11?Ga. This relatively narrow range suggests that reworking of the ancient crust beneath the Nakyn and Upper Muna kimberlite fields was minor, compared with the Daldyn and Alakit-Markha fields (Shatsky et al., 2016). This study, when combined with dating of detrital zircons, implies that tectonic-thermal events at 2.9-2.85, 2.75-2.7 and 2.0-1.95?Ga occurred everywhere on the Anabar tectonic province, and could reflect the upwelling of superplumes at 2.9, 2.7 and 2?Ga. The presence of the same tectonic-thermal events in the Daldyn and Markha terranes (Rosen et al., 2006a,b) supports the conclusion that the identification of the Markha terrane as a separate unit is not valid.
DS201806-1243
2018
Malkovets, V.G.Rezvukhin, D.I., Malkovets, V.G., Sharygin, I.S., Tretiakova, I.G., Griffin, W.L., O'Reilly, S.Y.Inclusions of crichtonite group minerals in Cr-pyropes from the Internationalnaya kimberlite pipe, Siberian craton: crystal chemistry, parageneses and relationships to mantle metasomatism.Lithos, Vol. 308, 1, pp. 181-195.Russiadeposit - International

Abstract: Cr-pyrope xenocrysts and associated inclusions of crichtonite-group minerals from the Internatsionalnaya kimberlite pipe were studied to provide new insights into processes in the lithospheric mantle beneath the Mirny kimberlite field, Siberian craton. Pyropes are predominantly of lherzolitic paragenesis (Cr2O3 2-6?wt%) and have trace-element spectra typical for garnets from fertile mantle (gradual increase in chondrite-normalized values from LREE to MREE-HREE). Crichtonite-group minerals commonly occur as monomineralic elongated inclusions, mostly in association with rutile, Mg-ilmenite and Cr-spinel within individual grains of pyrope. Sample INT-266 hosts intergrowth of crichtonite-group mineral and Cl-apatite, while sample INT-324 contains polymineralic apatite- and dolomite-bearing assemblages. Crichtonite-group minerals are Al-rich (1.1-4.5?wt% Al2O3), moderately Zr-enriched (1.3-4.3?wt% ZrO2), and are Ca-, Sr-, and occasionally Ba-dominant in terms of A-site occupancy; they also contain significant amounts of Na and LREE. T-estimates and chemical composition of Cr-pyropes imply that samples represent relatively low-T peridotite assemblages with ambient T ranging from 720 to 820°?. Projected onto the 35?mW/m2 cratonic paleogeotherm for the Mirny kimberlite field (Griffin et al., 1999b. Tectonophysics 310, 1-35), temperature estimates yield a P range of ~34-42?kbar (~110-130?km), which corresponds to a mantle domain in the uppermost part of the diamond stability field. The presence of crichtonite-group minerals in Cr-pyropes has petrological and geochemical implications as evidence for metasomatic enrichment of some incompatible elements in the lithospheric mantle beneath the Mirny kimberlite field. The genesis of Cr-pyropes with inclusions of crichtonite-group minerals is attributed to the percolation of Ca-Sr-Na-LREE-Zr-bearing carbonate-silicate metasomatic agents through Mg- and Cr-rich depleted peridotite protoliths. The findings of several potentially new members of the crichtonite group as inclusions in garnet extend existing knowledge on the compositions and occurrences of exotic titanates stable in the lithospheric mantle.
DS201808-1788
2018
Malkovets, V.G.Shatsky, V.S., Malkovets, V.G., Belousova, E.A., Tretiakova, I.G., Griffin, W.L., Ragozin, A.L., Wang, Q., Gibsher, A.A., O'Reilly, S.Y.Multi stage modification of Paleoarchean crust beneath the Anabar tectonic provnce ( Siberian craton).Precambrian Research, Vol. 305, pp. 125-144.Russiatectonics

Abstract: According to present views, the crustal terranes of the Anabar province of the Siberian craton were initially independent blocks, separated from the convecting mantle at 3.1 (Daldyn terrane), 2.9 (Magan terrane) and 2.5?Ga (Markha terrane) (Rosen, 2003, 2004; Rosen et al., 1994, 2005, 2009). Previous studies of zircons in a suite of crustal xenoliths from kimberlite pipes of the Markha terrane concluded that the evolution of the crust of the Markha terrane is very similar to that of the Daldyn terrane. To test this conclusion we present results of U-Pb and Hf-isotope studies on zircons in crustal xenoliths from the Zapolyarnaya kimberlite pipe (Upper Muna kimberlite field), located within the Daldyn terrane, and the Botuobinskaya pipe (Nakyn kimberlite field) in the center of the Markha terrane. The data on xenoliths from the Botuobinskaya kimberlite pipe record tectonothermal events at 2.94, 2.8, 2.7 and 2?Ga. The event at 2?Ga caused Pb loss in zircons from a mafic granulite. U-Pb dating of zircons from the Zapolyarnaya pipe gives an age of 2.7?Ga. All zircons from the studied crustal xenoliths have Archean Hf model ages ranging from 3.65 to 3.11?Ga. This relatively narrow range suggests that reworking of the ancient crust beneath the Nakyn and Upper Muna kimberlite fields was minor, compared with the Daldyn and Alakit-Markha fields (Shatsky et al., 2016). This study, when combined with dating of detrital zircons, implies that tectonic-thermal events at 2.9 -2.85, 2.75 -2.7 and 2.0 -1.95?Ga occurred everywhere on the Anabar tectonic province, and could reflect the upwelling of superplumes at 2.9, 2.7 and 2?Ga. The presence of the same tectonic-thermal events in the Daldyn and Markha terranes (Rosen et al., 2006a,b) supports the conclusion that the identification of the Markha terrane as a separate unit is not valid.
DS201911-2544
2019
Malkovets, V.G.Malkovets, V.G., Rezvukhin, D.I., Griffin, W.L., Tretiakova, I.G., Pearson, N.J., Gibsher, A.A., Belousova, E.A., Zedgenizov, D.A., O'Reilly, S.Y.Re-Os dating of sulfide inclusions in Cr-pyropes from the Upper Muna kimberlites.Goldschmidt2019, 1p. AbstractRussiadeposit - Upper Muna

Abstract: Archean cratons are underlain by highly depleted subcontinental lithospheric mantle (SCLM). However, there are extensive evidences that Archean SCLM has been extensively refertilized by metasomatic processes, with the addition of Fe, Ca, and Al to depleted protoliths. The distribution of sub-calcic Cr-rich garnets in the SCLM beneath the Siberian craton suggests (1) sub-calcic garnets and diamonds are metasomatic phases in the cratonic SCLM; (2) the distribution of both phases is laterally heterogeneous on relatively small scales and related to ancient structural controls [1]. Re-Os isotopic compositions of twenty six sulfide inclusions in lherzolitic Cr-pyropes from Upper Muna kimberlites have been determined by laser ablation MCICPMS. Most analysed sulfides (~92%) have very low Re/Os ratios (<0.07), and their Re-depletion ages (TRD) form three major peaks: 3.4-2.8, 2.2-1.8 and 1.4-1.2 Ga (±0.03 Ga, mean 2s analytical uncertainty). One sulfide give the oldest TRD age at 4 Ga. Our data suggest that refertilization of the highly depleted SCLM and the introduction of Cr-pyrope garnet occurred in several episodes. The oldest age of ca 4 Ga indicate on the beginning of the formation of the depleted SCLM of the Siberian Craton in Hadean time [2].
DS202006-0908
2020
Malkovets, V.G.Afanasiev, V.P., Pokhilenko, N.P., Grinenko, V.S., Kostin, A.V., Malkovets, V.G., Oleinikov, O.B.Kimberlitic magmatism in the south western flank of the Vilui basin. ( pyrope from Kenkeme River catchment) Jurassic-Cretaceous barren kimberlites.Doklady Earth Science, Vol. 490, 2, pp. 51-54.Russiageochronology

Abstract: We have analyzed 141 grains of pyrope from Neogene sediments in a quarry of construction materials, in the Kenkeme River catchment, along its left-side tributary (Chakiya River), about 60 km northwest of Yakutsk city. The mineral chemistry patterns of pyropes are typical of Jurassic-Cretaceous barren kimberlites, like the pipes of Obnazhennaya or Muza, but are uncommon to diamondiferous Middle Paleozoic kimberlites. The results allow identifying the magmatic event and placing time constraints on kimberlite magmatism in the southeastern flank of the Vilui basin, which was part of the Late Jurassic-Early Cretaceous tectonic-magmatic event in northeastern Asia.
DS202104-0591
2021
Malkovets, V.G.Malkovets, V.G., Shatsky, V.S., Dak, A.I., Gibsher, A.A., Yakovlev, I.V., Belousova, E.A., Tsujimori, T., Sobolev, N.V.Evidence for multistage and polychronous alkaline-ultrabasic Mesozoic magmatism in the area of diamondiferous placers of the Ebelyakh River basin, ( eastern slope of the Anabar shield).Doklady Earth Sciences, Vol. 496, 1, pp. 48-52.Russiadeposit - Anabar

Abstract: New mineralogical and isotope-geochemical data for zircon megacrysts (n = 48) from alluvium of Kholomolokh Creek (a tributary of the Ebelakh River) are reported. Using the geochemical classification schemes, the presence of zircons of kimberlitic and carbonatitic genesis was shown. The U-Pb dating of zircons revealed two major age populations: the Triassic (258-221 Ma, n = 18) and Jurassic (192-154 Ma, n = 30). Weighted mean 206Pb/238U ages allowed us to distinguish the following age stages: 155 ± 3, 161 ± 2, 177 ± 1.5, 183 ± 1.5, 190 ± 2, 233 ± 2.5, and 252 ± 4 Ma. It is suggested that the Ebelyakh diamonds could have been transported from the mantle depths by kimberlite, as well as by other related rocks, such as carbonatite, lamprophyre, lamproite, olivine melilitite, etc. Diamonds from the Ebelyakh placers most likely have polygenic native sources and may be associated with polychronous and multistage Middle Paleozoic and Mesozoic kimberlite and alkaline-ultrabasic magmatism in the eastern slope of the Anabar Shield (the Ebelyakh, Mayat, and Billyakh river basins).
DS202105-0779
2021
Malkovets, v.G.Nikolenko, E.I., Sharygin, I.S., Rezvukhin, D.I., Malkovets, v.G., Tychkov, N.S., Pokhilenko, N.P.Sulfide-bearing polymineralic inclusions in mantle-derived garnets from lamprophyres of the Chompolo field, (Central Aldan, Siberian Craton).Doklady Earth Sciences, Vol. 497, pp. 300-304.Russia, Siberiadeposit - Chompolo

Abstract: Sulfide-bearing polymineralic inclusions in mantle-derived chromium pyrope garnets of lherzolite paragenesis from lamprophyres of the Chompolo field (Aldan shield, southern Siberian craton) have been studied. The inclusions are composed of either only sulfides or sulfides in association with other minerals (carbonates, silicates, oxides, etc.). The sulfide part of the inclusions is represented by up to four minerals. Among the sulfides, minerals rich in Cu and Ni have been found, whereas Fe sulfides (pyrrhotite, troilite) are absent. This distinguishes the inclusions studied from the majority of sulfide inclusions in mantle minerals and diamonds, as well as in mantle xenoliths from kimberlites. The formation of polymineralic inclusions in chromium garnets of the Chompolo field is attributed to the effect of a carbonate-silicate metasomatic melt/fluid on mantle peridotites, as evidenced by the mineral suite associated with the sulfides. The research results indicate significant differences in the nature of metasomatic processes that occurred in the lithospheric mantle of the southern and central parts of the Siberian craton.
DS202106-0964
2021
Malkovets, V.G.Perchuk, A.L., Sapegina, A.V., Safonov, O.G., Yapaskurt, V.O., Shatsky, V.S., Malkovets, V.G.Reduced amphibolite facies conditions in the Precambrian continental crust of the Siberian craton recorded by mafic granulite xenoliths from the Udachnaya kimberlite pipe, Yakutia.Precambrian Research, Vol. 357, 1061022, 14p. PdfRussia, Yakutiadeposit - Udachnaya

Abstract: It is widely accepted that granulite xenoliths from kimberlites provide a record of granulite facies metamorphism at the basement of cratons worldwide. However, application of the phase equilibria modeling for seven representative samples of mafic granulites from xenoliths of the Udachnaya kimberlite pipe, Yakutia, revealed that a granulitic garnet + clinopyroxene + plagioclase ± orthopyroxene ± amphibole ± scapolite mineral assemblage was likely formed in the middle crust under amphibolite facies conditions (600-650 °C and 0.8-1.0 GPa) in a deficiency of fluid. Clinopyroxene in the rocks is characterized by elevated aegirine content (up to 10 mol.%) both in the earlier magmatic cores and in the later metamorphic rim zones of the grains. Nevertheless, the phase equilibrium modeling for all samples indicates surprisingly reduced conditions, i.e. oxygen fugacity 1.6-3.3 log units below the FMQ (Fayalite-Magnetite-Quartz) buffer. In contrast, the coexistence of Fe-Ti oxides indicates temperatures of 850-990 °C and oxygen fugacity about lg(FMQ) ± 0.5, conditions which correspond to earlier stages of rock evolution. Reduction of oxygen fugacity during cooling is discussed in the context of the evolution of a complex fluid. The reconstructed P-T conditions for the final equilibration in the mafic granulites indicate that temperatures were ~250 °C higher than those extrapolated from the continental conductive geotherm of 35-40 µW/m2 deduced from peridotite xenoliths of the Udachnaya pipe. Although the granulites resided in the crust for a period for at least 1.4 Ga, they did not re-equilibrate to the temperatures of the geotherm, likely due to the blocking of mineral reactions under relatively low temperatures and fluid-deficient conditions
DS202112-1945
2021
Malkovets, V.G.Sharygin, I.S., Golovin, A.V., Dymshits, A.M., Kalugina, A.D., Solovev, K.A., Malkovets, V.G., Pokhilenko, N.P.Relics of deep alkali-carbonate melt in the mantle xenolith from the Komosomolskaya-Magnitnaya kimberlite pipe ( Upper Muna field, Yakutia).Doklady Earth Sciences, Vol. 500, 2, pp. 842-847.Russia, Yakutiadeposit - Komosomolskaya-Magnitnaya

Abstract: The results of study secondary crystallized melt inclusions in olivine of a sheared peridotite xenolith from the Komsomolskaya-Magnitnaya kimberlite pipe (Upper Muna field, Yakutia) are reported. Monticellite, phlogopite, tetraferriphlogopite KMg3(Fe3+)Si3O10(F,Cl,OH), apatite, aphthitalite K3Na(SO4)2, burkeite Na6CO3(SO4)2, and carbonates, namely calcite, nyerereite (Na,K)2Ca(CO3)2, shortite Na2Ca2(CO3)3, and eitelite Na2Mg(CO3)2, were detected among the daughter minerals of the melt inclusions by the method of confocal Raman spectroscopy. The abundance of alkali carbonates in the inclusions indicates the alkali-carbonate composition of the melt. Previously, identical inclusions of alkali-carbonate melt were reported in olivine of sheared peridotites from the Udachnaya pipe (Daldyn field). Melt inclusions in sheared peridotites are the relics of a crystallized kimberlite melt that penetrated into peridotites either during the transport of xenoliths to the surface or directly in the mantle shortly prior to the entrapment of xenoliths by the kimberlite magma. If the second scenario took place, the finds of alkali-carbonate melt inclusions in sheared peridotites carried from different mantle depths in the Udachnaya and Komsomolskaya-Magnitnaya kimberlite pipes indicate a large-scale metasomatic alteration of the lithospheric mantle of the Siberian Craton by alkaline-carbonate melts, which preceded the kimberlite magmatism. However, regardless of which of the two models proposed above is correct, the results reported here support the alkali-carbonate composition of primary kimberlite melts.
DS200712-0866
2007
Mall, D.M.Rajendra Prasad, B., Kesava Rao, G., Mall, D.M., Koteswarar Rao, P., Raju, S., Reddy, SridherTectonic implications of seismic reflectivity pattern observed over the Precambrian southern granulite terrain, India.Precambrian Research, Vol. 153, 1-2, pp. 1-10.IndiaGeophysics - seismics
DS200812-0707
2008
Mall, D.M.Mall, D.M., Pandey, O.P., Chandrakala, K., Reddy, P.R.Imprints of a Proterozoic tectonothermal anomaly below the 1.1 Ga kimberltic province of southwest Cuddapah basin, Dharwar craton ( Southern India).Geophysical Journal International, Vol. 172, 1, pp. 422-438.IndiaGeothermometry
DS200912-0471
2009
Mall, D.M.Mall, D.M., Pandev, O.P., Chandrakala, K., Reddy, P.R.Imprints of a Proterozoic tectonothermal anomaly below the 1.1 Ga kimberlitic province of southwest Cuddapah basin, Dharwar Craton, southern India.Geophysical Journal International, Vol. 172, 1, pp. 422-438.IndiaGeothermometry
DS201112-0168
2010
Mall, D.M.Chandrakala, K., Pandey, O.P., Mall, D.M., Sarkar, D.Seismic signatures of a Proterozoic thermal plume below southwestern part of the Cuddapah Basin, Dharwar craton.Journal of the Geological Society of India, Vol. 76, 6, pp.565-572.IndiaGeophysics - seismics
DS201112-0169
2010
Mall, D.M.Chandrakala, K., Pandey, O.P., Mall, D.M., Sarkar, D.Seismic signatures of a Proterozoic thermal plume below southwestern part of the Cuddapah basin, Dharwar craton.Journal of the Geological Society of India, Vol. 76, pp. 565-572.India, Andhra PradeshGeophysics - seismics kimberlite magmatism
DS201112-0715
2011
Mall, D.M.Nageswara Rao, B., Kumar, N., Singh, A.P., Prabhakar Rao, M.R.K., Mall, D.M., Singh, B.Crustal density structure across the Central Indian shear zone from gravity data.Journal of Asian Earth Sciences, Vol. 42, 3, pp. 341-353..IndiaGeophysics - Bundelkhand Craton
DS1989-0521
1989
Mall, M.R.Godson, R.H., Mall, M.R.Potential field geophysical programs for IBM compatible microcomputers, version 1.0; documentationUnited States Geological Survey (USGS) Open File, No. 89-0197-A-F, paper 4.00 discs @ 6.00 30.00GlobalComputer, Program -geophysics
DS201607-1307
2016
Mallard, C.Mallard, C., Coltice, N., Seton, M., Muller, R.D., Tackley, P.J.Subduction controls the distribution and fragmentation of Earth's tectonic plates.Nature, available eprintMantleSubduction, melting

Abstract: The theory of plate tectonics describes how the surface of Earth is split into an organized jigsaw of seven large plates1 of similar sizes and a population of smaller plates whose areas follow a fractal distribution2, 3. The reconstruction of global tectonics during the past 200 million years4 suggests that this layout is probably a long-term feature of Earth, but the forces governing it are unknown. Previous studies3, 5, 6, primarily based on the statistical properties of plate distributions, were unable to resolve how the size of the plates is determined by the properties of the lithosphere and the underlying mantle convection. Here we demonstrate that the plate layout of Earth is produced by a dynamic feedback between mantle convection and the strength of the lithosphere. Using three-dimensional spherical models of mantle convection that self-consistently produce the plate size -frequency distribution observed for Earth, we show that subduction geometry drives the tectonic fragmentation that generates plates. The spacing between the slabs controls the layout of large plates, and the stresses caused by the bending of trenches break plates into smaller fragments. Our results explain why the fast evolution in small back-arc plates7, 8 reflects the marked changes in plate motions during times of major reorganizations. Our study opens the way to using convection simulations with plate-like behaviour to unravel how global tectonics and mantle convection are dynamically connected.
DS201710-2245
2017
Mallard, C.Mallard, C., Jacquet, B., Coltice, N.ADOPT: a tool for automatic detection of tectonic plates at the surface of convection model.Geochemistry, Geophysics, Geosystems, Vol. 18, 8, pp. 3197-3208.Mantletectonics

Abstract: Mantle convection models with plate-like behavior produce surface structures comparable to Earth's plate boundaries. However, analyzing those structures is a difficult task, since convection models produce, as on Earth, diffuse deformation and elusive plate boundaries. Therefore we present here and share a quantitative tool to identify plate boundaries and produce plate polygon layouts from results of numerical models of convection: Automatic Detection Of Plate Tectonics (ADOPT). This digital tool operates within the free open-source visualization software Paraview. It is based on image segmentation techniques to detect objects. The fundamental algorithm used in ADOPT is the watershed transform. We transform the output of convection models into a topographic map, the crest lines being the regions of deformation (plate boundaries) and the catchment basins being the plate interiors. We propose two generic protocols (the field and the distance methods) that we test against an independent visual detection of plate polygons. We show that ADOPT is effective to identify the smaller plates and to close plate polygons in areas where boundaries are diffuse or elusive. ADOPT allows the export of plate polygons in the standard OGR-GMT format for visualization, modification, and analysis under generic softwares like GMT or GPlates.
DS202009-1607
2020
Mallard, C.Arnould, M., Coltice, N., Flament, N., Mallard, C.Plate tectonics and mantle controls on plume dynamics.Earth and Planetary Science Letters, Vol. 547, 15p. PdfMantlegeodynamics

Abstract: Mantle plumes provide valuable information about whole-mantle convection: they originate at the core-mantle boundary, cross Earth's mantle and interact with the lithosphere. For instance, it has been proposed that the mobility/stability of plumes depends on plume intrinsic properties, on how slabs interact with the basal boundary layer, on mantle flow, or on their proximity to mid-ocean ridges. Here, we use 3D-spherical models of mantle convection generating self-consistent plate-like behaviour to investigate the mechanisms linking tectonics and mantle convection to plume dynamics. Our models produce fully-dynamic mantle plumes that rise vertically with deflection and present excess temperatures, rising speeds, buoyancy and heat fluxes comparable to observations. In the absence of plate tectonics, plumes are stable and their lifetime exceeds hundreds of million years. With plate tectonics, plumes are more mobile, and we identify four physical mechanisms controlling their stability. 1/ Fixed plumes are located at saddle points of basal mantle flow. 2/ Plumes moving at speeds between 0.5-1 cm yr?1 are slowly entrained by passive mantle flow. 3/ Fast plume motions between 2-5 cm yr?1 lasting several tens of million years are caused by slab push. 4/ Plumes occasionally drift at speeds >5 cm yr?1 over <10 Myr through plume merging. We do not observe systematic anchoring of plumes to mid-oceanic ridges. Independent of the presence of a dense basal layer, plate-like regimes decrease the lifetime of plumes compared to stagnant-lid models. Plume age, temperature excess or buoyancy flux are not diagnostic of plume lateral speed. The fraction of plumes moving by less than 0.5 cm yr?1 is >25%, which suggests that fixed hotspot reference frames can be defined from carefully selected hotspot tracks.
DS1991-1040
1991
Mallard, G.E.Mallard, G.E., Aronson, D.E.United States Geological Survey (USGS) toxic substances hydrology program; abstracts of the technicalmeeting, Monterey California, March 11-15th. 1991United States Geological Survey (USGS) Open File, No. 91-088, 133pUnited StatesToxic substances
DS1997-0719
1997
Mallard, L.D.Mallard, L.D., Rogers, J.J.W.Relationship of Avalonian and Cadomian terranes to Grenville and Pan-African events.Journal of Geodynamics, Vol. 23, No. 3-4, pp. 197-222.Ontario, Canada, EuropeTerranes, Tectonics
DS1992-0986
1992
Mallender, S.C.R.Mallender, S.C.R.New techniques for retrieving exploration dataGeobyte, Vol. 7, No. 1, pp. 15-19GlobalComputer, Program -Exploration data Program
DS1860-0155
1871
Mallet, F.R.Mallet, F.R.On the Vindhyan Series As Exhibited in the Northwest and Central Provinces of India.India Geological Survey Memoir., Vol. 7India, Madhya PradeshRegional Geology
DS1988-0435
1988
Mallet, J.L.Mallet, J.L.Three dimensional graphic display of disconnected bodiesMathematical Geology, Vol. 20, No. 8, November pp. 977-990. Database # 17576GlobalComputer, Program- Graphic
DS201812-2823
2018
Malley, J.A.S.Jerram, D.A., Sharp, T.H., Torsvik, T.H., Poulson, R., Watton, T.H., Freitag, U., Halton, A., Sherlock, S.C., Malley, J.A.S., Finley, A., Roberge, J., Swart, R., Fabregas, P., Ferreira, C.H., Machado, V.Volcanic constraints on the unzipping of Africa from South America: insights from new geochronological controls alone the Angola margin.Tectonophysics, doi.org/10.1016/ j.tecto.2018.07.027 33p.Africa, Angola, South Americageochronology

Abstract: The breakup of Africa from South America is associated with the emplacement of the Paraná-Etendeka flood basalt province from around 134 Ma and the Tristan da Cunha plume. Yet many additional volcanic events occur that are younger than the main pulse of the Paraná-Etendeka and straddle the rift to drift phases of the main breakup. This contribution reports on new geochronological constraints from the Angolan part of the African Margin. Three coastal and one inland section have been sampled stretching across some 400 Km, with 39Ar/40Ar, U-Pb and Palaeontology used to provide age constraints. Ages from the new data range from ~100 to 81 Ma, with three main events (cr. 100, 91 and 82-81 Ma). Volcanic events are occurring within the Early to Late Cretaceous, along this part of the margin with a general younging towards Namibia. With the constraints of additional age information both onshore and offshore Angola, a clear younging trend at the early stages of rift to drift is recorded in the volcanic events that unzip from North to South. Similar age volcanic events are reported from the Brazilian side of the conjugate margin, and highlight the need to fully incorporate these relatively low volume volcanic pulses into the plate tectonic breakup models of the South Atlantic Margin.
DS201312-0570
2013
Mallick, A.Mallick, A., Dasgupta, R.Reactive infiltration of MORB eclogite derived carbonated silicate melt into fertile peridotite at 3 Gpa and genesis of alkalic magmas.Journal of Petrology, Vol. 54, pp. 2267-2300.MantleAlkaline rocks, magmatism
DS202001-0050
2020
Mallick, A.Yaxley, G.M., Ghosh, S., Kiseeva, E.S., Mallick, A., Spandler, C., Thomson, A.R., Walter, M.J.Co2 rich melts in the earth.IN: Deep Carbon: past to present. Editors Orcutt, Danielle, Dasgupta, pp. 129-162.Mantlemelting

Abstract: This chapter reviews the systematics of partial melting of mantle lithologies - like peridotite and eclogite - in the presence of carbon dioxide. It discusses the composition of mantle-derived magmas generated in the presence of carbon dioxide and whether magmas erupted on Earth’s surface resemble carbonated magmas from the mantle. It reviews how the production of carbon dioxide-rich magma in the mantle varies as a function of tectonic settings - beneath continents and oceans and in subduction zones - and time.
DS1975-0986
1979
Mallick, D.I.J.Cornwell, J.D., Mallick, D.I.J.Reconnaissance Ground Geophysical Survey of the Xade Complex Central Botswana.Botswana Geological Survey, Bulletin. No. 22, PP. 247-272.BotswanaGeophysics, Tectonics
DS1981-0280
1981
Mallick, D.I.J.Mallick, D.I.J., Habgood, F., Skinner, A.C.A Geological Interpretation of Land sat Imagery and Air Photography of Botswana.Overseas Geol. Min. Resour., No. 56, 39P.BotswanaTectonic, Structure, Kimberlite, Remote Sensing, Tectonics
DS2001-1194
2001
Mallick, K.Vasanthi, A., Mallick, K.Patterns of occurrence of kimberlite pipes based on gravity and magnetic anomalies in Wajrakarur LattavaramJournal of Geological Society India, Vol. 58, No. 3, pp. 251-60.India, Andhra PradeshGeophysics - gravity, magnetics, Deposit - Wajrakarur
DS2001-1195
2001
Mallick, K.Vasanthi, A., Mallick, K.Patterns of occurrence of kimberlite pipes based on gravity and magnetic anomalies in Wajrakarur LattavaraM.Journal Geological Society of India, Vol.58,pp.251-9.India, Andhra PradeshGeophysics - magnetics, Deposit - Wajrakarur - Lattavaram
DS2002-1652
2002
Mallick, K.Vasanthi, A., Mallick, K.Pattern of occurrence of kimberlite pipes based on gravity and magnetic anomalies in Wajrakarur Lattavaram region, Andhra Pradesh.COMMENTSJournal of Geological Society of India, Vol. 60, Sept. pp. 3590-51.India, Andhra PradeshGeophysics - corrections
DS200412-2045
2002
Mallick, K.Vasanthi, A., Mallick, K.Pattern of occurrence of kimberlite pipes based on gravity and magnetic anomalies in Wajrakarur Lattavaram region, Andhra PradesJournal of Geological Society of India, Vol. 60, Sept. pp. 3590-51.India, Andhra PradeshGeophysics - corrections
DS200512-1127
2005
Mallick, K.Vasanthi, A., Mallick, K.Bouguer gravity anomalies and occurrence patterns of kimberlite pipes in Narayanpet Maddur regions, Andhra Pradesh, India.Geophysics, Vol. 70, 1, Jan-Feb. pp. J13-J24.India, Andhra PradeshGeophysics - gravity
DS200512-1128
2005
Mallick, K.Vasanthi, A., Mallick, K.Bouguer gravity modeling of central Cuddaph Basin.Journal of the Geological Society of India, Vol. 66, 2, pp. 171-184.IndiaGeophysics - gravity
DS200612-1471
2005
Mallick, K.Vasanthi, A., Mallick, K.Occurrence pattern of kimberlite pipes as reflected by gravity and magnetic anomalies.Geological Society of India, Bangalore November Meeting Group Discussion on Kimberlites and Related Rocks India, Abstract p. 69-70.India, Andhra Pradesh, Dharwar CratonGeophysics
DS200612-1472
2006
Mallick, K.Vasanthi, A., Mallick, K.Further confirmation of kimberlite/lamproite occurrences in concentric ring pattern in Andhra Pradesh. Wajrakarur, Chigicherla, Chelima, NarayanpetJournal of the Geological Society of India, Vol. 68, August pp. 332-333.IndiaTectonics - kimberlites
DS200812-0943
2008
MallikRay, R., Shukia, A.D., Sheth, H.C., Ray, J.S., Duraiswami, Vanderkluysen, Rautela, MallikHighly heterogeneous Precambrian basement under the central Deccan Traps, India: direct evidence from xenoliths in dykes.Gondwana Research, Vol. 13, 3, pp. 375-385.IndiaPetrology - dykes
DS201112-0236
2011
Mallik, A.Dasgupta, R., Tsuno, K., Withers, A.C., Mallik, A.Silicate melting in the Earth's deep upper mantle caused by C-O-H volatiles.Goldschmidt Conference 2011, abstract p.724.MantleCarbonatite
DS201312-0186
2013
Mallik, A.Dasgupta, R., Mallik, A., Tsuno, K., Withers, A.C., Hirth, G., Hirschmann, M.M.Carbon dioxide rich silicate melt in the Earth's upper mantle.Nature, Vol. 493, Jan. 10, pp. 211-215.MantleMelting
DS201906-1319
2018
Mallik, A.Mallik, A., Li, Y., Wiedenbeck, M.Nitrogen evolution within the Earth's atmosphere-mantle system assessed by recycling in subduction zones.Earth and Planetary Science Letters, Vol. 482, pp. 556-566.Mantlenitrogen

Abstract: Understanding the evolution of nitrogen (N) across Earth's history requires a comprehensive understanding of N's behaviour in the Earth's mantle - a massive reservoir of this volatile element. Investigation of terrestrial N systematics also requires assessment of its evolution in the Earth's atmosphere, especially to constrain the N content of the Archaean atmosphere, which potentially impacted water retention on the post-accretion Earth, potentially causing enough warming of surface temperatures for liquid water to exist. We estimated the proportion of recycled N in the Earth's mantle today, the isotopic composition of the primitive mantle, and the N content of the Archaean atmosphere based on the recycling rates of N in modern-day subduction zones. We have constrained recycling rates in modern-day subduction zones by focusing on the mechanism and efficiency of N transfer from the subducting slab to the sub-arc mantle by both aqueous fluids and slab partial melts. We also address the transfer of N by aqueous fluids as per the model of Li and Keppler (2014). For slab partial melts, we constrained the transfer of N in two ways - firstly, by an experimental study of the solubility limit of N in melt (which provides an upper estimate of N uptake by slab partial melts) and, secondly, by the partitioning of N between the slab and its partial melt. Globally, 45-74% of N introduced into the mantle by subduction enters the deep mantle past the arc magmatism filter, after taking into account the loss of N from the mantle by degassing at mid-ocean ridges, ocean islands and back-arcs. Although the majority of the N in the present-day mantle remains of primordial origin, our results point to a significant, albeit minor proportion of mantle N that is of recycled origin (% or % of N in the present-day mantle has undergone recycling assuming that modern-style subduction was initiated 4 or 3 billion years ago, respectively). This proportion of recycled N is enough to cause a departure of N isotopic composition of the primitive mantle from today's N of ?5‰ to ‰ or ‰. Future studies of Earth's parent bodies based on the bulk Earth N isotopic signature should take into account these revised values for the N composition of the primitive mantle. Also, the Archaean atmosphere had a N partial pressure of 1.4-1.6 times higher than today, which may have warmed the Earth's surface above freezing despite a faint young Sun.
DS200612-0455
2001
Mallik, A.K.Ghosh Roy, A.K., Mukhopashyay, P.K., Mallik, A.K.Some alkaline complexes of West Bengal, Orissa and Andhra Pradesh - potential hosts for semi-precious and precious stones.National Seminar on Exploration Survey, Geological Society of India Special Publication, No. 58, pp. 671-676IndiaAlkalic
DS1990-0973
1990
Mallikarjuna Rao, J.Madhavan, V., Mallikarjuna Rao, J.Petrology of olivine basalt dyke of lamprophyre affinity at Uppalapadu, Prakasam District, Andhra PradeshJournal of Geological Society India, Vol. 36, November pp. 493-501IndiaLamprophyre dike, Petrology
DS1992-0983
1992
Mallikharjuna, J.Madhavan, V., Mallikharjuna, J., et al.Geochemistry and petrogenesis of lamprophyres and associated dykes fromElchuru, Andhra Pradesh, India.Journal Geological Society of India, Vol. 40, August pp. 135-149.IndiaLamprophyres, minettes, sannaite, camptonite, Geochemistry
DS1989-0920
1989
Mallikharjuna Rao, J.Madhaven, V., Mallikharjuna Rao, J., Subrahmanyam, K., KrishnaBedrock geology of the Elchuru alkaline pluton,Prakasam District, AndhraPradeshGeological Society of India, Memoir, Editor C. LeelanandaM., No. 15, pp. 189-206IndiaAlkaline rocks, Lamprophyres
DS201012-0471
2010
Mallikharjuna Rao, J.Mallikharjuna Rao, J.Mafic and alkaline dykes of Swangkre, Shilong Plateau, north east India.International Dyke Conference Held Feb. 6, India, 1p. AbstractIndiaIjolite, carbonatite
DS1992-0982
1992
Mallikharjuna Rao, J. Balaram. V.Madhavan, V., Mallikharjuna Rao, J. Balaram. V., Kumar, R.Geochemistry and petrogenesis of lamprophyres and associated dikes fromElchuru, Andhra Pradesh, IndiaJournal of Geological Society India, Vol. 40, No. 2, August pp. 135-150IndiaLamprophyres, Petrology
DS200712-0676
2007
Mallman, G.Mallman, G., O'Neill, H.S.The effect of oxygen fugacity on the partitioning of Re between crystals and silicate melt during mantle melting.Geochimica et Cosmochimica Acta, Vol. 71, 11, pp. 2837-2857.MantleMelting
DS200712-0677
2007
Mallmann, G.Mallmann, G., O'Neill, H.St.C.The effect of oxygen fugacity on the partitioning of Re between crystals and silicate melt during mantle melting.Geochimica et Cosmochimica Acta, Vol. 71, 11, June 1, pp. 2837-2857.MantleMelting
DS200712-0791
2007
Mallmann, G.O'Neill, H.St.C., Mallmann, G.The P/Nd ratio of basalt as an indicator of pyroxenite in its source.Plates, Plumes, and Paradigms, 1p. abstract p. A741.MantleMelting
DS201112-0758
2011
Mallmann, G.O'Neill, H.St., Berry, A.J., Mallmann, G.Redox variable trace elements.Goldschmidt Conference 2011, abstract p.1557.TechnologyGeochemical properties
DS200512-0990
2005
Mallory, S.Simandl, G.J., Ferbey, T., Levson, V.M., Demchuk, T.E., Mallory, S., Smith, L.R., Kjarsgaard, I.Kimberlite indicator minerals in the Fort Nelson area, northeastern British Columbia.British Columbia Geological Survey, Summary of Fieldwork, Paper 2005-1, pp. 325-343.Canada, British ColumbiaGeochemistry, geomorphology, glacial, KIMS
DS200512-0365
2005
Mallory-Greenough, L.M.Greenough, J.D., Dostal, J., Mallory-Greenough, L.M.Igneous rock association- pt. 4 Oceanic volcanism 1 mineralogy and petrology.Geoscience Canada, Vol. 32, 1, March pp. 29-45.MantleHotspots, tectonics, basalts
DS1970-0129
1970
Malloy, M.J.Malloy, M.J.An Exercise in Terrace Identification and Correlation in The Alluvial Gravels of the Orange River in Southwest Africa.Petros, Vol. 2, PP. 20-22.Southwest Africa, NamibiaGeomorphology, Alluvial Diamond Placers
DS201712-2705
2017
Mallozzi, S.McPeak, S., Mallozzi, S., Samson, C., Elliott, B., Junter, J.Estimating overburden depth in a permafrost rich environment using passive seismics: results from the 2017 preliminary survey at Kennady Camp.45th. Annual Yellowknife Geoscience Forum, p. 103 abstract posterCanada, Northwest Territoriesdeposit - Kennady
DS2001-0513
2001
Malmsten, C.Irving, M., Malmsten, C., Elliot, D.Diamond value added in Canada's Northwest Territories37th. Forum Industrial Minerals;, May 23-5, p. 89.Northwest TerritoriesEconomics
DS200612-0851
2006
Malod, J.Maillard, A., Malod, J., Thiebot, E., Klingelhoefer, F., Rehault, J-P.Imaging a lithospheric detachment at the continent ocean crustal transition off Morocco.Earth and Planetary Science Letters, Vol. 241, 3-4, Jan. 31, pp. 686-698.Africa, MoroccoGeophysics - seismics, exhumation
DS200412-0353
2004
Malod, J.P.Contrucci, I., Klingelhofer, J., Perrot, R., Bartolome, M.A., Gutscher, M., Sahabi, J., Malod, J.P.The crustal structure of the NW Moroccan continental margin from wide angle reflection seismic data.Geophysical Journal International, Vol. 159, 1, pp. 117-128.Africa, MoroccoGeophysics - seismics, Tectonics
DS1991-0107
1991
Malogolovets, V.G.Beskrovanov, V.V., Spetsuius, Z.V., Malogolovets, V.G., KhrenovMorphology and physical properties of diamonds from mantlexenoliths.(Russian)Mineral. Zhurn., (Russian), Vol. 13, No. 5, October pp. 31-42RussiaDiamond morphology, Xenoliths
DS201811-2562
2018
Malone, D.Craddock, J., Malone, D., Schmitz, M.D., Gifford, J.N.Strain variations across the Proterozoic Penokean Orogen, USA and Canada. Sudbury impact Precambrian Research, Vol. 318, pp. 25-69.United States, Canadaorogeny

Abstract: Strata in the Huron (2.5-2.0 Ga) and Animikie (2.2-1.85 Ga) basins were deposited on the southern margin of the Archean Superior province. These rocks were deformed during the Penokean orogeny (?1850 Ma) followed by subsequent accretionary orogens to the south at 1750 Ma (Yavapai) and 1630 Ma (Mazatzal). Strain patterns are unique to each orogenic belt with no far-field effect: Archean Wawa terrane rocks in the Penokean foreland preserve deformation associated with Archean accretion with no younger Penokean, Yavapai or Mazatzal strain overprint. The Penokean orogeny deformed Huron-Animikie basin sediments into a north-vergent fold-and-thrust belt with no Yavapai or Mazatzal strain overprint. Yavapai orogen strains (SW-NE margin-parallel shortening) are unique when compared to the younger Mazatzal shortening (N20°W) shortening, with no strain overprint. Penokean deformation is characterized by shortening from the south including uplifted Archean gneisses and a northerly thin-skinned fold-and-thrust belt, with north-vergent nappes and a gently-dipping foreland. Our study of finite and calcite twinning strains (n=60) along (?1500 km) and across (?200 km) the Penokean belt indicate that this orogeny was collisional as layer-parallel shortening axes are parallel across the belt, or parallel to the tectonic transport direction (?N-S). Penokean nappe burial near the margin resulted in vertical shortening strain overprints, some of which are layer-normal. The Sudbury impact layer (1850 Ma) is found across the Animikie basin and provides a widespread deformation marker with many local, unique strain observations. We also report new geochronology (U-Pb zircon and apatite) for the gneiss-mafic dike rocks at Wissota (Chippewa Falls, WI) and Arbutus (Black River Falls, WI) dams, respectively, which bears on Penokean-Yavapai deformation in the Archean Marshfield terrane which was accreted during the Penokean orogen. Pseudotachylite formation was common in the Superior province Archean basement rocks, especially along terrane boundaries reactivated by contemporaneous Penokean, Trans-Hudson, Cape Smith and New Quebec deformation. In the hinterland (south), the younger Yavapai orogen (1750 Ma; n=8) deformation is preserved as margin-parallel horizontal shortening (?SW-NE) in Yavapai crust and up to 200 km to the north in the Penokean thrust belt as a strain and Barrovian metamorphic overprint. Mazatzal deformation (1630 Ma; n=16) is preserved in quartzites on Yavapai and Penokean crust with layer-parallel and layer-normal shortening strains oriented N20°W.
DS200712-0943
2007
Malone, S.D.Scandone, R., Cashman, K.V., Malone, S.D.Magma supply, magma ascent and the style of volcanic eruptions.Earth and Planetary Science Letters, Vol. 253, 3-4, Jan. 30, pp. 513-529.MantleMagmatism
DS200612-0497
2006
Malone, S.J.Gregory, L.C., Meert, J.G., Pradhan, V., Pandit, M.K., Tamrat, E., Malone, S.J.A paleomagnetic and geochronologic study of the Majhgawan kimberlite. India: implications for the age of the Upper Vindhyan Supergroup.Precambrian Research, Vol. 149, 1-2, pp. 65-75.IndiaDeposit - Majhgawan, geophysics, geochronology
DS201012-0596
2010
Malone, S.J.Pradhan, V.R., Meert, J.G., Pandit, M.K., Kamenov, G., Gregory, L.C., Malone, S.J.India's changing place in global Proterozoic reconstructions: a review of geochronologic constraints and paleomagnetic poles from the Dharwar Bundelk hand and MarwarJournal of Geodynamics, Vol. 50, 3-4, pp. 224-242.IndiaCraton, crustal evolution
DS201412-0908
2014
Maloof, A.C.Swanson-Hysell, N.L., Burgess, S.D., Maloof, A.C., Bowring, S.A.Magmatic activity and plate motion during the latent stage of Midcontinent Rift development.Geology, Vol. 42, pp. 475-478.United StatesStructure - rifting
DS201605-0813
2016
Malope, K.Bomman, F., Malope, K.Investigation of the optimal vortex finder length in DMS cyclones.Diamonds Still Sparkling SAIMM 2016 Conference, Mar. 14-17, pp. 229-238.TechnologyDMS - applied
DS2001-0723
2001
Malov, A.I.Malov, A.I.Magnesium in brines from the Svernaya Dvin a Artesian basin as an indicator of kimberlite magmatism.Doklady Academy of Sciences, Vol. 377, No. 2, Feb-Mar. pp.225-28.RussiaGeochemistry, Magmatism
DS200412-1211
2004
Malov, A.I.Malov, A.I.The role of exogenic groundwaters in kimberlite formations.Doklady Earth Sciences, Vol. 395, 4, March-April, pp. 453-455.RussiaGenesis
DS201802-0251
2017
Malov, A.I.Malov, A.I., Sidkina, E.S., Ryzhenko, B.N.Model of the Lomonosov diamond deposit as a water rock system: migration species, groundwater saturation with rock forming and ore minerals, and ecological assessment of water quality.Geochemistry International, Vol. 55, 12, pp. 1118-1130.Russiadeposit - Lomonosov

Abstract: Thermodynamic numerical simulations were carried out to determine the principal simple and complex migration species of Ca, Mg, Na, K, Al, B, Mn, Mo, Sr, and U with Cl-, OH-, SO4?2, HCO3?, and CO32? in waters at the Lomonosov diamond deposit and to estimate the saturation indexes with respect to kaolinite, Na- and Mg-montmorillonite, Mg- and Na-saponite, muscovite and paragonite, biotite, phlogopite, chromite, pyrite, plagioclase (anorthite, labradorite, and andesine), olivine (forsterite and fayalite), diopside, pyrope, gypsum, anhydrite, barite, magnesite, calcite, dolomite, talc, chrysotile, chlorite, goethite, quartz, microcline, and albite. The waters are proved not to be saturated with respect to the primary (hydrothermal) minerals. The saturation of certain water samples with uranophane suggests that this mineral is of secondary genesis. The ascent of highly mineralized deep waters shall result in the dissolution of minerals whose concentrations are near the saturation ones. To maintain the ecological standards of the discharged waters, they should be diluted and/or purified by adsorbing dissolved U on a reducing reactive barrier.
DS1985-0349
1985
Malov, Y.V.Klopotov, V.I., Malov, Y.V., Ovsyannikov, Y.A.Reaction Rims on Picroilmenites from KimberlitesGeochemistry International, Vol. 22, No. 3, pp. 117-124RussiaGeochemistry, Alteration, Metasomatism
DS1985-0358
1985
Malov, Y.V.Koslov, A.A., Malov, Y.V., Semenov, G.S.Mineral concentrators of manganese in some kimberlites ofSiberianPlatform*(in Russian)Geochemistry International (Geokhimiya), (Russian), No. 5, pp. 781-783RussiaBlank
DS1990-0874
1990
Malov, Y.V.Kononova, V.A., Makhotkin, I.L., Malov, Y.V., Bogatikov, O.A.Lamproites and petrochemical series of potassium rocks.(Russian)Izves. Akad. Nauk SSSR, (Russian), Ser, Geol. No. 11, November pp. 55-65RussiaLamproites, Petrochemistry
DS1990-0976
1990
Malov, Y.V.Malov, Y.V., Ovsyanni.. E.A., Ostrocski, B.M.Typomorphic associations of kimberlite ilmenites.(Russian)Geochemistry International (Geokhimiya), (Russian), No. 6, June pp. 815-822RussiaMineralogy, Ilmenites
DS1983-0373
1983
Malov, YU.Kozlov, A.A. , Malov, YU., Semenov, G.S.Manganese Concentrators of Some Siberia Platform KimberlitesGeokimiya., No. 5, PP. 781-790.RussiaMineralogy
DS1984-0412
1984
Malov, YU.V.Klopotov, V.I., Malov, YU.V., Ousyannikov, E.A.Reaction Rims on Picroilmenites from KimberlitesGeochemistry International (Geokhimiya)., No. 10, OCTOBER PP. 1466-1473.RussiaMineralogy, Microprobe, Analyses, Geochemistry
DS1991-1041
1991
Malov, Yu.V.Malov, Yu.V., Ovsyannikov, Ye.A., Ostrovisky, B.M.Type assemblages of kimberlite ilmenitesGeochemistry International, Vol. 28, No. 1, pp. 43-50RussiaMineral chemistry, Ilmenite analyses
DS201910-2256
2019
Malovets, V.Dymshits, A., Sharygin, I., Yakolev, I., Malovets, V.Thermal state and composition of the lithospheric mantle beneath the Upper Muna kimberlite field, Yakutia.Goldschmidt2019, 1p. AbstractRussia, Yakutiadeposit - Upper Muna

Abstract: Mantle xenoliths brought up by kimberlitic magmas are the main source of data on the composition and physical conditions of cratonic mantle. Temperature varioations in a complete lithospheric mantle section (80-200 km) of the Siberian craton beneath the Upper Muna kimberlite filed are estimated based 49 peridotite xenolith and 330 Cpx grains from the Komsomolskaya-Magnitnaya pipe. Pressure and temperature estimates closely follow the 34.5 mW/m2 conductive geotherm. Thermal lithospere thickness is of ~ 220 km, and “diamond window” in the Paleozoic is ~75 km thick (Fig.1). Olivine compositions range in Mg# from 82 to 94 and the majority of olivenes has very high Mg# > 93. Garnets compositions mainlly follow to harzburgite-dunite and lherzolite trends plotted as Cr2O3 vs CaO. The composition of the minerals indicated the extremly depleted lithospheric mantle beneath the Upper-Muna kimberlite field. Figure 1: Model palaeogeotherms calculated using the program FITPLOT. Komsomolskaya-Magnitnaya - our data, Novinka and Udachaya are from Z16 [1]
DS201412-0544
2014
Malowa, M.Malowa, M.Variation in average diamond size in the MOR paleo gravel deposits on SRC and BHC terraces on the Saxen drift mine.GSSA Kimberley Diamond Symposium and Trade Show provisional programme, Sept. 10-12, POSTERAfrica, South AfricaDeposit - Saxendrift
DS1975-0482
1977
Malpas, J.Collerson, K.D., Malpas, J.Partial Melts in Upper Mantle Nodules from Labrador Kimberlites.International Kimberlite Conference SECOND., EXTENDED ABSTRACT VOLUME.Canada, Quebec, LabradorBlank
DS1986-0519
1986
Malpas, J.Malpas, J., Foley, S.F., King, A.F.Alkaline mafic and ultramafic lamprophyres from the Aillik Bayarea, LabradorCanadian Journal of Earth Sciences, Vol. 23, No.12, December pp. 1902-1918CanadaQuebec, Labrador
DS1986-0520
1986
Malpas, J.Malpas, J., Foley, S.F., King, A.F.Alkaline mafic and ultramafic lamprophyres from the Allik Bay area, Labrador.Canadian Journal of Earth Sciences, Vol. 23, pp. 1902-18.Quebec, LabradorAlkalic rocks, Deposit - Allik Bay area
DS1990-0977
1990
Malpas, J.Malpas, J., Moores, E.M., Pantayiotou, A., Xenophontos, C.Ophiolites- oceanic crustal analoguesCyprus Geological Survey, 733p. $ 65.00Japan, Indonesia, California, Oregon, Mid-Atlantic Ridge, ScotlandOphiolites, Book -ad
DS1991-0791
1991
Malpas, J.Jenner, G.A., Dunning, G.R., Malpas, J., Brown, M., Brace, T.Bay of Islands and Little Port complexes, revisited: age, geochemical and isotopic evidence confirm suprasubduction-zone originCanadian Journal of Earth Sciences, Vol. 28, No. 10, October pp. 1635-1652NewfoundlandOphiolites, Geochronology
DS1993-0964
1993
Malpas, J.Malpas, J.Deep drilling of the Oceanic crust and Upper MantleGsa Today, Vol. 3, No. 3, March pp. 53-57MantleCrust, Drilling, magma chambers
DS1993-0965
1993
Malpas, J.Malpas, J.Deep drilling of the oceanic crust and upper mantleGsa Today, Vol. 3, No. 3, March pp. 53-57.MantleDrilling
DS1995-0483
1995
Malpas, J.Edwards, S.J., Malpas, J.Multiple origins for mantle harzburgites: examples from the Lewis Hills, Bay of Islands ophiolite.Canadian Journal of Earth Sciences, Vol. 32, No. 7, July pp. 1046-1057.NewfoundlandHarzburgites
DS1997-0720
1997
Malpas, J.Malpas, J., Robinson, P.The origin and evolution of Oceanic lithosphere: introductionGeoscience Canada, Vol. 24, No. 2, pp. 100-107MantleLithosphere - evolution, ophiolites, Oceanic - rates, Pacific, Indian
DS1998-0242
1998
Malpas, J.Chen, N.S., Sun, M., Malpas, J.Well preserved garnet growth zoning in granulite from the Dabie Mountains central China.Journal of Metamorphic Geology, Vol. 16, No. 2, March pp. 213-222.Chinametamorphism, Dabie Mountains
DS2000-0609
2000
Malpas, J.Malpas, J., Robinson, P.T.No. 4The origin and evolution of oceanic lithosphere: magmatic processes at oceanic spreading centresGeoscience Canada, Vol. 27, No. 3, Sept. pp. 131-46.MantlePlumes, geophysics, magma chambers, ophiolites
DS200412-1212
2004
Malpas, J.Malpas, J., Fletcher, C.J.N., Aitchison, J.C.Aspects of the tectonic evolution of China.Geological Society of London Special Paper, No. 226, 368p. $140.ChinaBook - tectonics
DS200512-0680
2004
Malpas, J.Malpas, J., Fletcher, C.J.N., Ali, J.R., Aitchison, J.C.Aspects of the tectonic evolution of China.Geological Society of London , Special Publication 226, 368p. $134.ChinaBook - tectonics
DS201112-0871
2004
Malpas, J.Robinson, P.T., Bai, W-J., Malpas, J., Yang, J-S., Zhou, M-F., Fang, Q-S., Hu, X-F., Cameron, StaudigelUltra high pressure minerals in the Loubasa ophiolite, Tibet and their tectonic implications.Aspects of the Tectonic evolution of China, Editors Fletcher, Ali, Aitchison, Geological Society Of America, Spec. Pub.226, pp.247-71China, TibetUHP
DS201905-1041
2019
Malpe, D.B.Hazarika, B., Malpe, D.B., Dongre, A.Petrology and geochemistry of a boninite dyke from the western Bastar craton of central India.Journal of Earth System Science, Vol. 128:32Indiacraton

Abstract: The Dongargarh Supergroup along with the basal Amgaon Gneissic Complex constitutes the northwestern part of the central Indian Bastar craton. In the present study, we report a new finding of a boninite dyke intruded in the Amgaon gneisses of this area. The dyke composed of mainly pyroxenes, amphiboles and subordinate amount of plagioclase. The higher contents of SiO2 (51-54 wt.%), MgO (12-14 wt.%), Ni (375-473 ppm), Cr (1416-1580 ppm) and very low TiO2 (0.2-0.4 wt.%) are consistent with the boninite nature of the dyke as well as the unevolved primary nature of the source magma. The extraordinarily high CaO content (15.97-17.7 wt.%) with higher CaO/Al2O3 (3.13-3.96) ratios classifies it as high-Ca boninite. The trace element ratios including Zr/Ti, Ti/V, Ti/Sc and Ti/Yb further show its geochemical similarity with the Archaean boninite. The dyke also shows negative high-field strength element (Nb, Ta and Ti) anomalies which are the characteristics of the boninite rocks reported elsewhere and along with the enriched light rare earth element pattern, it shows more affinity particularly with the northern Bastar boninite dyke. The mineralogical and geochemical similarities of the boninite dykes from the Bastar craton indicate a widespread boninitic event during the Palaeoproterozoic having a similar origin. These boninite dykes indicate the preservation of subduction-related signatures in the lithospheric mantle beneath the Bastar craton at the time of its evolution or may be during the convergence of the Bastar and Bundelkhand cratons.
DS202002-0192
2019
Malpe, D.B.Hazarika, B., Malpe, D.B., Dongre, A.Petrology and geochemistry of a boninite dyke from the western Bastar craton of central India.Journal of Earth System Science, Vol. 128, 17p. PdfIndiaboninite

Abstract: The Dongargarh Supergroup along with the basal Amgaon Gneissic Complex constitutes the northwestern part of the central Indian Bastar craton. In the present study, we report a new finding of a boninite dyke intruded in the Amgaon gneisses of this area. The dyke composed of mainly pyroxenes, amphiboles and subordinate amount of plagioclase. The higher contents of SiO2 (51-54 wt.%), MgO (12-14 wt.%), Ni (375-473 ppm), Cr (1416-1580 ppm) and very low TiO2 (0.2-0.4 wt.%) are consistent with the boninite nature of the dyke as well as the unevolved primary nature of the source magma. The extraordinarily high CaO content (15.97-17.7 wt.%) with higher CaO/Al2O3 (3.13-3.96) ratios classifies it as high-Ca boninite. The trace element ratios including Zr/Ti, Ti/V, Ti/Sc and Ti/Yb further show its geochemical similarity with the Archaean boninite. The dyke also shows negative high-field strength element (Nb, Ta and Ti) anomalies which are the characteristics of the boninite rocks reported elsewhere and along with the enriched light rare earth element pattern, it shows more affinity particularly with the northern Bastar boninite dyke. The mineralogical and geochemical similarities of the boninite dykes from the Bastar craton indicate a widespread boninitic event during the Palaeoproterozoic having a similar origin. These boninite dykes indicate the preservation of subduction-related signatures in the lithospheric mantle beneath the Bastar craton at the time of its evolution or may be during the convergence of the Bastar and Bundelkhand cratons.
DS202003-0342
2020
Malpe, D.B.Hazarika, B., Malpe, D.B., Dongre, A.Petrogenesis of mafic dykes from the western Bastar craton of central India and their relation to ourgrowth of Columbia supercontinent.Mineralogy and Petrology, in press available, 20p. PdfIndiacraton

Abstract: We report mineral compositions and bulk rock geochemistry of mafic dykes intruded in the western part of Bastar craton, comprising of Archaean Amgaon Group and Proterozoic Dongargarh Supergroup of rocks. Field relations show two distinct trends of these dykes which are almost perpendicular to each other but having similar mineralogical and geochemical characteristics. Dykes are mostly composed of pyroxenes, plagioclase and subordinate amount of amphiboles and Fe-Ti oxides (magnetite and ilmenite). These hypersthene normative basaltic dykes show tholeiitic trend and are characterised by narrow compositional variations of MgO (6.067.08 wt%), FeOt (15.0617.78 wt%), TiO2 (1.182.24 wt%), Al2O3 (11.9615.54 wt%) and low Mg# [atomic Mg/(Mg?+?Fe2+)?×?100] values in the range of 3748. Low loss on ignition (LOI) values <2 wt% and significant trends of trace elements (Nb, La, Th, Sr) with Zr indicate insignificant effects of post magmatic processes in these dykes. Smooth correlations between major oxides and MgO, among trace element ratios (Ce/La, Th/Yb, Nb/Yb) and negative Nb-Ta anomalies without positive Zr and Hf anomalies negate the crustal contamination effects. The correlations of compatible (e.g. Cr, Ni) and incompatible (e.g. Ba, Rb) elements show involvement of both fractional crystallisation and partial melting processes in their formation. Flat heavy rare earth element (HREE) pattern with low (Tb/Yb)n values reveal their genesis from a mantle source without involvement of garnet and geochemical models suggested in the present study indicate melting from spinel lherzolite mantle source. Strong geochemical similarities of present dykes with those of earlier reported Lakhna (1.46 Ga) and Bandimal (1.42 Ga) dykes of northern Bastar craton suggest a widespread mafic magmatic event across the Bastar craton during 1.421.46 Ga. Present dykes therefore represent a subduction related outgrowth of Columbia supercontinent due to the accretion of continental margins.
DS201312-0160
2013
Malpeli, K.C.Chirico, P.G., Malpeli, K.C.Preventing the trade of conflict diamonds and supporting artisanal mining.apogeospatial.com, Summer, 5p.Africa, Ivory Coast, Sierra Leone, Liberia, AngolaBrief use of satellite imagery
DS201610-1852
2010
Malpeti, K.C.Chirico, P.G., Malpeti, K.C., Anum, S., Phillips, E.C.Alluvial diamond resource potential and production capacity assessment of Ghana.U.S. Geological Survey, Report 2010-5045, 25p.Africa, GhanaAlluvials, resources

Abstract: In May of 2000, a meeting was convened in Kimberley, South Africa, and attended by representatives of the diamond industry and leaders of African governments to develop a certification process intended to assure that rough, exported diamonds were free of conflictual concerns. This meeting was supported later in 2000 by the United Nations in a resolution adopted by the General Assembly. By 2002, the Kimberley Process Certification Scheme (KPCS) was ratified and signed by both diamond-producing and diamond-importing countries. Over 70 countries were included as members at the end of 2007. To prevent trade in "conflict" diamonds while protecting legitimate trade, the KPCS requires that each country set up an internal system of controls to prevent conflict diamonds from entering any imported or exported shipments of rough diamonds. Every diamond or diamond shipment must be accompanied by a Kimberley Process (KP) certificate and be contained in tamper-proof packaging. The objective of this study was to assess the alluvial diamond resource endowment and current production capacity of the alluvial diamond-mining sector in Ghana. A modified volume and grade methodology was used to estimate the remaining diamond reserves within the Birim and Bonsa diamond fields. The production capacity of the sector was estimated using a formulaic expression of the number of workers reported in the sector, their productivity, and the average grade of deposits mined. This study estimates that there are approximately 91,600,000 carats of alluvial diamonds remaining in both the Birim and Bonsa diamond fields: 89,000,000 carats in the Birim and 2,600,000 carats in the Bonsa. Production capacity is calculated to be 765,000 carats per year, based on the formula used and available data on the number of workers and worker productivity. Annual production is highly dependent on the international diamond market and prices, the numbers of seasonal workers actively mining in the sector, and environmental conditions, which influence seasonal farming.
DS201610-1853
2014
Malpeti, K.C.Chirico, P.G., Malpeti, K.C., Van Bockstael, M., Mamandou, D., Cisse, K., Diallo, T.A., Sano, M.Alluvial diamond resource potential and production capacity assessment of Guinea.U.S. Geological Survey, Report 2012-5256, 49p.Africa, GuineaAlluvials, resources

Abstract: In May of 2000, a meeting was convened in Kimberley, South Africa, by representatives of the diamond industry and leaders of African governments to develop a certification process intended to assure that export shipments of rough diamonds were free of conflict concerns. Outcomes of the meeting were formally supported later in December of 2000 by the United Nations in a resolution adopted by the General Assembly. By 2002, the Kimberley Process Certification Scheme (KPCS) was ratified and signed by diamond-producing and diamond-importing countries. The goal of this study was to estimate the alluvial diamond resource endowment and the current production capacity of the alluvial diamond mining sector of Guinea. A modified volume and grade methodology was used to estimate the remaining diamond reserves within Guinea’s diamondiferous regions, while the diamond-production capacity of these zones was estimated by inputting the number of artisanal miners, the number of days artisans work per year, and the average grade of the deposits into a formulaic expression. Guinea’s resource potential was estimated to be approximately 40 million carats, while the production capacity was estimated to lie within a range of 480,000 to 720,000 carats per year. While preliminary results have been produced by integrating historical documents, five fieldwork campaigns, and remote sensing and GIS analysis, significant data gaps remain. The artisanal mining sector is dynamic and is affected by a variety of internal and external factors. Estimates of the number of artisans and deposit variables, such as grade, vary from site to site and from zone to zone. This report has been developed on the basis of the most detailed information available at this time. However, continued fieldwork and evaluation of artisanally mined deposits would increase the accuracy of the results.
DS1998-0928
1998
Malpos, J.Malpos, J., Robinson, P.T.Oceanic lithosphere 2. the origin and evolution: bathymetry and morphology of ocean basinsGeoscience Canada, Vol. 25, No. 3, Sept. pp. 128-138OceansContinental margins, ridges, Lithosphere
DS200412-0459
2004
Malservisi, R.Dixon, J.E., Dixon, T.H., Bell, D.R., Malservisi, R.Lateral variation in upper mantle viscosity: role of water.Earth and Planetary Science Letters, Vol. 222, 2, pp. 451-467.United States, ColoradoWater - chemistry, xenoliths
DS201012-0022
2010
Malskov, B.A.Askhabov, A.M., Malskov, B.A.Quataron model of the impact origin of carbonado.Doklady Earth Sciences, Vol. 435, 1, pp. 1476-1477.South America, BrazilCarbonado - clusters, nitrogen
DS1859-0033
1824
Malte-Brun.Eyries, J.B., Malte-Brun.Mines de Diamant de PortyallParis: Nouvelles Annales Des Voyages, Vol. 21, PP. 228-233.Southeast Asia, Malaysia, BorneoDiamond Occurrence
DS202004-0527
2020
Maltese, A.Maltese, A., Mezger, K.The pb isotope evolution of bulk silicate Earth: constraints from its accretion and early differentiation history.Geochimica et Cosmochimica Acta, Vol. 271, pp. 179-193.Mantlemeteorites

Abstract: Constraining the evolution of Pb isotopes in the bulk silicate Earth (BSE) is hampered due to the lack of a direct determination of Earth’s U/Pb and initial Pb isotope composition. All estimates of these parameters are strongly model dependent and most Pb evolution models start with a meteoritic source, i.e., the primordial Pb composition determined in troilite from the Canyon Diablo iron meteorite. During the condensation of the elements in the solar nebula, accretion of the Earth, and its subsequent chemical evolution, the U/Pb was modified. Different models make different assumptions about the timing and extent of this U-Pb fractionation during Earth’s chemical evolution that cannot always be related to known global geological processes at the time of this modification. This study explores geochemical constraints that can be related to known geological processes to derive an internally consistent model for the evolution of the U-Th-Pb systematics of the silicate Earth. Lead is chalcophile, moderately volatile, and as a result strongly depleted in the BSE compared to primitive meteorites. Any process affecting the abundance and isotope composition of Pb in Earth throughout its early history has to be consistent with the abundance of elements with similar chemical and physical properties in the same reservoir. The abundances of refractory to moderately and highly volatile elements in the BSE imply that the proto Earth was highly depleted in volatile elements, and therefore evolved with a very high U/Pb (238U/204Pb?=?µ???100) prior to collision with the Moon-forming giant impactor. This impactor had close to chondritic abundances of moderately to highly volatile elements and delivered most of Earth’s volatile elements, including the Pb budget. Addition of this volatile-rich component caused oxidation of Earth’s mantle and allowed effective transfer of Pb into the core via sulfide melt segregation. Sequestration of Pb into the core therefore accounts for the high µBSE, which has affected ca. 53% of Earth’s Pb budget. In order to account for the present-day Pb isotope composition of BSE, the giant impact must have occurred at 69?±?10 Myr after the beginning of the solar system. Using this point in time, a model-derived µ-value and the corresponding initial Pb isotope composition of BSE, a single stage Pb isotope evolution curve can be deduced. The result is a model evolution curve for BSE in 208Pb-207Pb-206Pb-204Pb-isotope space that is fully consistent with geochemical constraints on Earth’s accretionary sequence and differentiation history. This Pb-evolution model may act as a reference frame to trace the silicate Earth’s differentiation into crust and mantle reservoirs, similar to the CHUR reference line used for other radio-isotope systems. It also highlights the long-standing Th/U paradox of the ancient Earth.
DS201012-0235
2009
Maltezos, G.Gilbertson, A., Gudlewski, B., Jhonson, M., Maltezos, G., Scherer, A., Shigley, J.Cutting diffraction gratings to improve dispersion ( 'fire') in diamonds. A new process of plasma eteching diffraction patterns on diamond facets.Gems & Gemology, Vol. 45, 4, Winter pp. 260-270.TechnologyDiamond cutting
DS1989-1422
1989
MaltsevSobolev, N.V., Galimov, E.M., Smith, C.B., Yefimova, E.S., MaltsevA comp study of the morphology, inclusions and C I composition of diamondsSoviet Geology and Geophysics, Vol. 30, No. 12, pp. 1-19AustraliaMicrodiamonds, Alluvial diamonds
DS1989-0462
1989
Maltsev, K.A.Galimov, E.M., Kaminskiy, F.V., Maltsev, K.A., Sobolev, N.V.Relation of carbon isotopic composition with parageneses of mineral inclusions in diamonds in paired kimberlite pipes.(Russian)Geochemistry International (Geokhimiya), (Russian), No. 5, pp. 754-758RussiaGeochronology - C Isotope, Diamond inclusions
DS1989-0922
1989
Maltsev, K.A.Maltsev, K.A.Isotopic composition of hydrogen in diamonds.(Russian)Doklady Academy of Sciences Akademy Nauk SSSR, (Russian), Vol. 308, No. 6, pp. 1451-1453RussiaDiamond morphology, Isotope -Hydrogen in diaM.
DS1990-0506
1990
Maltsev, K.A.Galimov, E.M., Kaminisky, F.V., Maltsev, K.A., Sobolev, N.V.The relation between delta 13 C and mineral inclusion assemblages in diamonds from paired kimberlite pipesGeochemistry International, Vol. 26, No. 12, pp. 134-137RussiaDiamond inclusions, carbon, Delta 13 C analyses
DS1990-0507
1990
Maltsev, K.A.Galimov, E.M., Kuznetsov, V.P., Maltsev, K.A., Gorbachev, V.V.Isotopic composition of diamonds bearing the inclusions of diamond.(Russian)Geochemistry International (Geokhimiya), (Russian), No. 7, July pp. 1033-1040RussiaDiamond inclusions, Geochronology
DS1990-0896
1990
Maltsev, K.A.Kuznetsova, V.P., Maltsev, K.A., Gorbachev, V.V., Zezin, R.B.Isotopic composition of diamonds bearing inlclusions of diamonds.(Russian)Geochemistry International (Geokhimiya), (Russian), No. 7, July pp. 1033-1039RussiaDiamond inclusions, Diamonds
DS1991-0528
1991
Maltsev, K.A.Galimov, E.M., Kuznetsova, V.P., Maltsev, K.A., Gorbachev, V.V.Isotope composition of diamonds containing diamond inclusionsGeochemistry International, Vol. 28, No. 1, pp. 115-121RussiaGeochronology, Diamond inclusions
DS1991-1042
1991
Maltsev, K.A.Maltsev, K.A., Galimov, E.M.Isotope distribution in hydrogen of diamondDoklady Academy of Science USSR, Earth Science Section, Vol. 308, No. 5, pp. 229-230RussiaDiamond inclusions, Hydrogen
DS1992-0987
1992
Maltsev, K.A.Maltsev, K.A.Nitrogen aggregation and the isotope composition of carbon and nitrogen indiamonds.Geochemistry International, Vol. 29, No. 7, pp. 140-144.RussiaGeochronology, Diamond inclusions
DS1994-0563
1994
Maltsev, K.A.Galimov, E.M., Zakharch, O.D., Maltsev, K.A., Makhin, A.I.The isotopic composition of carbon in diamonds from the kimberlitic pipe sat Archangelsk.(Russian)Geochemistry International (Geokhimiya), (Russian), No. 1, pp. 67-74.Russia, Yakutia, ArkangelskGeochronology, Diamond inclusions -carbon
DS1995-0575
1995
Maltsev, K.A.Galimov, E.M., Bao Yannan, K.A., Maltsev, K.A., SmirnovaIsotopic composition of diamonds from the North Chinese PlatformDoklady Academy of Sciences Acad. Science Russia, Vol. 331A, No. 6, June pp. 189-192.ChinaGeochronology, Diamonds
DS1994-1095
1994
Maltsev, K.A.KlyuyevMaltsev, K.A.Klyuyev, Yu.A.Nitrogen aggregation in diamonds and diamond formationGeochemistry International, Vol. 31, No. 4, pp. 99-102.GlobalDiamond genesis, Nitrogen
DS2001-0724
2001
Malunga, G.W.P.Malunga, G.W.P., Kalindekafe, L.S.Geology and economic potential of Malawi carbonatitesJournal of South African Earth Sciences, Vol. 32, No. 1, p. A 25. (abs)MalawiCarbonatite, Chilwa Alkaline Province
DS2002-1379
2002
Malveev, Yu.A.Safonov, O.G., Malveev, Yu.A., Litvin, Y.A., Perchuk, L.L., Bindi, L., MenchettiUltrahigh pressure study of potassium bearing clinopyroxene equilibria18th. International Mineralogical Association Sept. 1-6, Edinburgh, abstract p.74.Russia, YakutiaUHP, mineralogy, Kokchteav Complex, kimberlites
DS202202-0190
2022
Malviya, V.P.Dora, M.L., Randive, K., Meshram, R., Meshram, T., Baswani, S.R., Korakoppa, M., Malviya, V.P.Petrogenesis of a calc-alkaline lamprophyre ( minette) from Thanewasna western Bastar craton, central India: insights from mineral, bulk rock and in-situ trace element geochemistry.Geological Society of London Special Publication 513, pp. 179-207.Indiaminette

Abstract: The lamproites and kimberlites are well known from the Eastern Bastar Craton, Central India. However, a Proterozoic lamprophyre dyke is discussed here, from the Western Bastar Craton (WBC). The field geology, petrographic, mineralogical and whole-rock and in-situ trace element geochemistry of biotite are described to understand the petrogenesis and lithospheric evolution in the WBC. The Thanewasna lamprophyre (TL) is undeformed and unmetamorphosed, intruded into c. 2.5 Ga charnockite and metagabbro but closely associated with c. 1.62 Ga undeformed Mul granite. The TL has a characteristic porphyritic texture, dominated by phenocrysts of biotite, microphenocryst of amphibole, clinopyroxene and a groundmass controlled by feldspar. Mineral chemistry of biotite and amphibole suggest a calc-alkaline (CAL) type, and pyroxene chemistry reveals an orogenic setting. The TL is characterized by high SiO2 and low TiO2, MgO, Ni and Cr, consistent with its subcontinental lithospheric origin. The presence of crustal xenolith and ocelli texture followed by observed variations in Th/Yb, Hf/Sm, La/Nb, Ta/La, Nb/Yb, Ba/Nb indicate substantial crustal contamination. Whole-rock and in-situ biotite analysis by laser ablation inductively coupled plasma mass spectrometry show low concentrations of Ni (30-50 ppm) and Cr (70-150 ppm), pointing to the parental magma evolved nature. Enrichment in H2O, reflected in magmatic mica dominance, combined with high large ion lithophile element, Th/Yb ratios, and striking negative Nb-Ta anomalies in trace element patterns, is consistent with a source that was metasomatized by hydrous fluids corresponding to those generated by subduction-related processes. Significant Zr-Hf and Ti anomalies in the primitive mantle normalized multi-element plots and the rare earth element pattern of the TL, similar to the global CAL average trend, including Eastern Dharwar Craton lamprophyres. Our findings provide substantial petrological and geochemical constraints on petrogenesis and geodynamics. However, the geodynamic trigger that generated CAL magmatism and its role in Cu-Au metallogeny in the WBC, Central India, is presently indistinct in the absence of isotopic studies. Nevertheless, the lamprophyre dyke is emplaced close to the Cu-(Au) deposit at Thanewasna.
DS201902-0294
2018
Malyeshev, S.V.Malyeshev, S.V., Pasenko, A.M., Ivanov, A.V., Gladkochub, D.P., Savatenkov, V.M., Meffre, S., Abersteiner, A., Kamenetsky, V.S., Shcherbakov, V.D.Geodynamic significance of the Mesoproterozoic magmatism of the Udzha paleo-rift ( Northern Siberian craton) based in U-Pb geochronology and paleomagnetic data.Minerals ( mdpi.com), Vol. 8, 12, 11p. PdfRussia, Siberiacraton

Abstract: The emplacement age of the Great Udzha Dyke (northern Siberian Craton) was determined by the U-Pb dating of apatite using laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS). This produced an age of 1386 ± 30 Ma. This dyke along with two other adjacent intrusions, which cross-cut the sedimentary units of the Udzha paleo-rift, were subjected to paleomagnetic investigation. The paleomagnetic poles for the Udzha paleo-rift intrusions are consistent with previous results published for the Chieress dyke in the Anabar shield of the Siberian Craton (1384 ± 2 Ma). Our results suggest that there was a period of intense volcanism in the northern Siberian Craton, as well as allow us to reconstruct the apparent migration of the Siberian Craton during the Mesoproterozoic.
DS200812-0053
2008
MalyginaAshchepkov, Pokhilenko, Vladykon, Loginova, Rotman, Afansiev, Kuligin, Malygina, Alymova, Stegnitsky, KhmetnikovaPlume interaction and evolution of the continental mantle lithosphere.Deep Seated Magmatism, its sources and plumes, Ed. Vladykin, N.V., 2008 pp. 104-121.MantlePlume
DS200912-0016
2009
MalyginaAschepokov, L., Logvinova, A., Kuligin, Pokhilenko, Vladykin, Mityukhin, Alymova, Malygina, VishnyakovaClinopyroxene eclogite peridotite thermobarometry of the large Yakutian kimberlite pipes.Goldschmidt Conference 2009, p. A58 Abstract.Russia, YakutiaThermobarometry
DS201012-0018
2010
MalyginaAshchepkov, I.V., Pokhilenko, Vladykin, Logvinova, Afansiev, Kuligin, Malygina, Alymova, KostrovitskyStructure and evolution of the lithospheric mantle beneath Siberian Craton, theromobarometric study.Tectonophysics, Vol. 485, pp. 17-41.RussiaGeothermometry
DS201112-0037
2010
MalyginaAshchepkov, Ntaflos, Vladykin, Ionov, Kuligin, Malygina, Pokhilenko, Logvinova, Mityukhin, Palessky, Khmelnikova, RotmasDeep seated xenoliths from the phlogopite bearing brown breccia of the Udachnaya pipe.Vladykin, N.V., Deep Seated Magmatism: its sources and plumes, pp. 164-186.RussiaMetasomatism
DS2003-0871
2003
Malygina, E.V.Malygina, E.V., Pokhilenko, N.P., Sobolev, N.V.Coarse peridotite xenoliths of Udachnaya kimberlite pipe, Yakutia: garnetization of8 Ikc Www.venuewest.com/8ikc/program.htm, Session 6, POSTER abstractRussia, Siberia, YakutiaDeposit - Udachnaya
DS200412-1213
2003
Malygina, E.V.Malygina, E.V., Pokhilenko, N.P., Sobolev, N.V.Coarse peridotite xenoliths of Udachnaya kimberlite pipe, Yakutia: garnetization of peridotites of the central Siberian platform8 IKC Program, Session 6, POSTER abstractRussia, Siberia, YakutiaMantle petrology Deposit - Udachnaya
DS200412-1563
2003
Malygina, E.V.Pokhilenko, N.P., Griffin, W.L., Shimizu, N., McLean, R.C., Malkovets, V.G., Pokhilenko, L.N., Malygina, E.V.Pyropes and chromites of the Snap Lake King Lake kimberlite dyke system in relation to the problem of the southern Slave Craton8 IKC Program, Session 6, POSTER abstractCanada, Northwest TerritoriesMantle petrology Deposit - Snap Lake King Lake
DS200812-1190
2008
Malygina, E.V.Tychkov, N.S., Pokhilenko, N.P., Kuligin, S.S., Malygina, E.V.Composition and origin of peculiar pyropes from lherzolites: evidence for the evolution of the lithospheric mantle of the Siberian Platform.Russian Geology and Geophysics, Vol. 49, 4, pp. 225-239.RussiaMineralogy - garnets
DS200912-0708
2009
Malygina, E.V.Sobolev, N.V., Logvinova, A.M., Zedgenizov, D.A., Pokhilenko, N.P., Malygina, E.V., Kuzmin, D.V., Sobolev, A.V.Petrogenetic significance of minor elements in olivines from diamonds and peridotite xenoliths from kimberlites of Yakutia.Lithos, In press - available 38p.Russia, YakutiaDiamond inclusions
DS201212-0440
2012
Malygina, E.V.Malygina, E.V., Pokhilenko, N.P.Pecurlarities of composition of coarse peridotite xenoliths of some kimberlite pipes of South Africa.10th. International Kimberlite Conference Held Bangalore India Feb. 6-11, Poster abstractAfrica, South AfricaDeposit - Bells Bank, Roberts Victor, Wesselton, Bostoff Road
DS201312-0045
2013
Malygina, E.V.Ashchepkov, I.V., Ntaflos, T., Kuligin, S.S., Malygina, E.V., Agashev, A.M., Logvinova, A.M., Mitukhin, S.I., Vladykin, N.V.Deep seated xenoliths from the brown breccia of the Udachnaya pipe, Siberia.Proceedings of the 10th International Kimberlite Conference, Vol. 1, Special issue of the Journal of Geological Society of India, Vol. 1, pp. 59-73.RussiaDeposit - Udachnaya
DS201412-0937
2014
Malygina, E.V.Tychkov, N.S., Agashev, A.M., Malygina, E.V., Nikolenko, E.I., Pokhilenko, N.P.Thermal pertubations in the lithospheric mantle as evidenced from P-T equilibrium conditions of xenoliths from the Udachnaya kimberlite pipe.Doklady Earth Sciences, Vol. 454, 1, pp. 84-88.Russia, YakutiaDeposit - Udachnaya
DS202012-2234
2020
Malygina, E.V.Mikhailenko, D.S., Stagno, V., Korsakov, A.V., Andreozzi, G.B., Marras, G., Cerantola, V., Malygina, E.V.Redox state determination of eclogite xenoliths from Udachnaya kimberlite pipe ( Siberian craton), with some implications for the graphite/diamond formation.Contributions to Mineralogy and Petrology, Vol. 175, 107, 17p. PdfRussiadeposit - Udachnaya

Abstract: The formation of diamonds within eclogitic rocks has been widely linked to the fate of carbon during subduction and, therefore, referred to conditions of pressure, temperature, and oxygen fugacity (fo2). Mantle-derived eclogite xenoliths from Udachnaya kimberlite pipes represent a unique window to investigate the formation of carbon-free, graphite-diamond-bearing and diamond-bearing rocks from the Siberian craton. With this aim, we exploited oxy-thermobarometers to retrieve information on the P-T-fo2 at which mantle eclogites from the Siberian craton equilibrated along with elemental carbon. The chemical analyses of coupled garnet and omphacitic clinopyroxene were integrated with data on their iron oxidation state, determined both by conventional and synchrotron 57Fe Mössbauer spectroscopy. The calculated fo2s largely vary for each suite of eclogite samples from 0.10 to ? 2.43 log units (?FMQ) for C-free eclogites, from ? 0.01 to ? 2.91 (?FMQ) for graphite-diamond-bearing eclogites, and from ? 2.08 to ? 3.58 log units (?FMQ) for diamond-bearing eclogites. All eclogite samples mostly fall in the fo2 range typical of diamond coexisting with CO2-rich water-bearing melts and gaseous fluids, with diamondiferous eclogites being more reduced at fo2 conditions where circulating fluids can include some methane. When uncertainties on the calculated fo2 are taken into account, all samples essentially fall within the stability field of diamonds coexisting with CO2-bearing melts. Therefore, our results provide evidence of the potential role of CO2-bearing melts as growth medium on the formation of coexisting diamond and graphite in mantle eclogites during subduction of the oceanic crust.
DS202108-1267
2021
Malygina, E.V.Agasheva, E.V., Kolesnichenko, M.V., Malygina, E.V., Agashev, A.M., Zedgenizov, D.A.Origin of water in mantle eclogites from the V. Grib kimberlite pipe, NW Russia.Lithosphere, Vol. 2021, 7866657, 18p. PdfRussia, Arkangelskdeposit - Grib

Abstract: The water content in the garnet and clinopyroxene in the mantle eclogites from the V. Grib kimberlite pipe (Arkhangelsk Diamondiferous Province, NW Russia) was analysed using Fourier transform infrared spectrometry. The results show that all clinopyroxene grains contained structural water at concentrations of 39 to 247?ppm, whereas two garnet samples contained detectable water at concentrations of 211 and 337?ppm. The low-MgO eclogites with oceanic gabbro precursors contained significantly higher water concentrations in the omphacites (70-247?ppm) and whole rock (35-224?ppm) compared to those with oceanic basalt protoliths (49-73?ppm and 20-36?ppm, respectively). The incorporation of water into the clinopyroxene may be associated with vacancies at the M2 site, Al in the tetrahedral position, and the elements that filled the M2 site (mostly Na and Ca). The highest water content in the omphacite was detected in a nonmetasomatised sample and was assumed to represent residual water that survived during subduction. Other eclogite samples showed signs of modal and/or cryptic metasomatism and contained less water in the omphacites compared to the nonmetasomatised sample. The water content was heterogeneous within the eclogite section of the sampled lithospheric mantle. The lack of distinct and uniform correlations between the indices of eclogite modification and their water content indicated that the saturation with water was disturbed during their residence within the lithospheric mantle.
DS202111-1775
2021
Malygina, E.V.Mikhailenko, D.S., Aulbach, S., Korsakov, A.V., Golovin, A.V., Malygina, E.V., Gerdes, A., Stepanov, A.S., Xu, Y-G.Origin of graphite-diamond bearing eclogites from Udachnaya kimberlite pipe.Journal of Petrology, Vol. 62, 8, pp. 1-32. pdfRussiadeposit - Udachnaya

Abstract: Kimberlite-borne mantle eclogites represent an important diamond source rock. Although the origin and stability of diamond, as opposed to its low-pressure polymorph graphite, have been studied for decades, their relationship in rare natural samples where both polymorphs coexist remains poorly constrained. To shed new light on this issue, seven graphite-diamond-bearing eclogites from the kimberlite pipe Udachnaya, Siberian craton were comprehensively investigated with respect to their petrography, mineral chemical composition and omphacite 87Sr/86Sr, acquired in situ by laser ablation multicollector inductively coupled plasma mass spectrometry. The calculated P-T conditions for basaltic group eclogites (Eu/Eu* < 1) correspond to a pressure range of 4•8-6•5?GPa and temperatures of 1060-1130?°C, whereas gabbroic eclogites with positive Eu- and Sr-anomalies have a smaller pressure variation (4•8-5•8?GPa), but a larger range in temperature (990-1260?°C). Reconstructed bulk compositions for gabbroic eclogites indicate an oceanic crustal origin for their protoliths, with accumulation of plagioclase and olivine ± clinopyroxene (gabbronorite or olivine gabbro). The protoliths of basaltic eclogites probably formed from the complementary residual melt. The presence of coesite and low Mg# in basaltic eclogites suggest that their light rare earth element depletion was the result of <10?% partial melting during subsequent subduction and emplacement into the cratonic lithosphere. Extremely unradiogenic 87Sr/86Sr (0•70091-0•70186 for six of seven samples) not only provides new evidence for the Archean age (2•5-2•9?Gyr) of Yakutian graphite-diamond-bearing eclogites and for formation of their protoliths in a depleted mantle source, but also suggests that they were not significantly metasomatically overprinted after their formation, despite their extended residence in the cratonic mantle lithosphere. The mineralogical and petrographic features indicate that the primary mineral association includes garnet, omphacite, ± coesite, ± kyanite, ± rutile, graphite, and diamond. Graphite occurs in the samples in the form of idiomorphic crystals (the longest dimensions being 0•4-1?mm) in garnet and kyanite and extends beyond their grain boundaries. Diamonds occur as octahedral cubic transparent, slightly colored or bright yellow crystals as large as 0•1-2?mm. Furthermore, idiomorphic and highly ordered graphite occurs as inclusions in diamond in four samples. The carbon isotope composition for diamond and graphite has a narrow range (?4 to ?6•6?‰) for both groups (gabbroic and basaltic), indicating a mantle source and limiting the role of subducted isotopically light biogenic carbon or reduction of isotopically heavy carbonate in diamond crystallization. Importantly, the presence of graphite and diamond inclusions in garnet, omphacite, and kyanite in three samples indicates a co-formation close in time to eclogitization. Combined, the petrographic and geochemical evidence suggests that both polymorphic carbon modifications can form in the diamond stability field, as also suggested by experiments and some natural examples, although the exact mechanism remains unresolved. Furthermore, this study provides natural evidence that graphite can be preserved (metastably) deep within the diamond stability field, without recrystallizing into diamond, for a long time, ?2•5?Gyr.
DS1975-0215
1975
Malyshev, A.A.Zabrodin, V.YU., Malyshev, A.A.New Alkalic Ultramafic and Carbonatite Complex on the Yenisei Ridge.Doklady Academy of Science USSR, Earth Science Section., Vol. 223, No. 1-6, PP. 195-198.RussiaKimberlite
DS1987-0396
1987
Malyshev, A.A.Lapin, A.V., Ploshko, V.V., Malyshev, A.A.Carbonatites of the Tatar deep seated fault zone on the Eniseiridge.(Russian)Geol. Rudn. Mestorozd., (Russian), Vol. 29, No. 1, pp. 30-45RussiaCarbonatite
DS1988-0401
1988
Malyshev, A.A.Lapin, A.V., Malyshev, A.A., Ploshko, V.V., Cherepivskaya, G.Ye.Strontiopyrochlore from lateritic weathered mantle of carbonatiteDoklady Academy of Science USSR, Earth Science Section, Vol. 290, No. 1-6, March pp. 188-192RussiaSupergene alteration, analyses, Carbonatite
DS1998-0926
1998
Malyshev, N.A.Malkov, B.A., Malyshev, N.A.Diamond occurrences in kimberlites and lamproites from Phanerozoic mobile belts an example of Timans, Urals..7th International Kimberlite Conference Abstract, pp. 540-2.Arkansas, Louisiana, Russia, Urals, ChinaMobile belts, Diatremes - rybalites
DS200912-0260
2008
Malyshev, Y.F.Goroshko, M.V., Malyshev, Y.F.Regional potassic metasomatism and metallogeny of Precambrian structural-stratigraphic unconformity zones ( southeastern Siberian Craton).Doklady Earth Sciences, Vol. 423, 2, pp. 1459-1461.RussiaMetasomatism
DS1990-0873
1990
Malyshonok, Yu.V.Konev, A.A., Vorobjev, E.I., Malyshonok, Yu.V., PiskyuNew dat a on the mineralogy of carbonatitesInternational Mineralogical Association Meeting Held June, 1990 Beijing China, Vol. 2, extended abstract p. 701-702RussiaCarbonatite, Classification -Sr Ba
DS1982-0388
1982
Malyuk, B.I.Malyuk, B.I.Chemical Composition of Basic and Ultrabasic Rocks As an Indicator of the Compositional In homogeneity of the Upper Mantle.Soviet Geology and GEOPHYS., Vol. 23, No. 7, PP. 114-116.RussiaGenesis, Geochemistry
DS1982-0389
1982
Malyuk, B.I.Malyuk, B.I., Sivoronov, A.A.On the Nature of KomatiitesGeology And Geophysics, Vol. 23, No. 4, PP. 26-33.RussiaWebsterite, Lherzolite, Classification, Komatiite
DS1985-0408
1985
Malyuk, B.I.Malyuk, B.I.The Origin of Komatiite Magmas: Petrochemical Test of ModelsInternational Geology Review, Vol. 27, No. 7, July pp. 770-780RussiaComparison To Kimberlite Magmas, Komatiite
DS1989-0923
1989
Malyuk, B.I.Malyuk, B.I.Basalt magma evolution in Precambrian greenstone beltsGeochemistry International, Vol. 26, No. 12, pp. 37-47RussiaGreenstone belt, Basalt magma
DS1992-1754
1992
Malyuk, B.I.Zolotukhin, V.V., Laguta, O.N., Malyuk, B.I.Genesis of komatiites of different continents, as inferred from dat a on their chemical compositionDoklady Academy of Science USSR, Earth Science Section, Vol. 312, No. 3, pp. 177-180RussiaKomatiites, Geochemistry
DS1992-1755
1992
Malyuk, B.I.Zolotukhin, V.V., Malyuk, B.I., Laguta, O.N.Genetic aspects of deep seated petrogenesis of komatiite magmasSoviet Geology and Geophysics, Vol. 33, No. 1, pp. 29-39Russia, Commonwealth of Independent States (CIS)Komatiite, Petrology
DS1992-1756
1992
Malyuk, B.I.Zolotukin, V.V., Malyuk, B.I., Laguta, O.N.Komatiites and the problem of basalt genesisRussian Geology and Geophysics, Vol. 33, No. 3, pp. 48-56Russia, Commonwealth of Independent States (CIS)Komatiites, Genesis -basalt
DS1994-1096
1994
Mamallan, R.Mamallan, R., et al.Jasra ultramafic mafic alkaline complex: a new find in the ShillongPlateau, northeastern India.Current Science, Vol. 66, No. 1, Jan. 10, pp. 64-65.IndiaAlkaline rocks, Jasra complex
DS1996-0795
1996
Mamallan, R.Kumar, D., Mamallan, R., Dwivedy, K.K.Carbonatite magmatism in northeast IndiaJournal of Southeast Asian Earth Sciences, Vol. 13, No. 2, Feb. 1, pp. 145-?IndiaCarbonatite, Magmatism
DS201610-1853
2014
Mamandou, D.Chirico, P.G., Malpeti, K.C., Van Bockstael, M., Mamandou, D., Cisse, K., Diallo, T.A., Sano, M.Alluvial diamond resource potential and production capacity assessment of Guinea.U.S. Geological Survey, Report 2012-5256, 49p.Africa, GuineaAlluvials, resources

Abstract: In May of 2000, a meeting was convened in Kimberley, South Africa, by representatives of the diamond industry and leaders of African governments to develop a certification process intended to assure that export shipments of rough diamonds were free of conflict concerns. Outcomes of the meeting were formally supported later in December of 2000 by the United Nations in a resolution adopted by the General Assembly. By 2002, the Kimberley Process Certification Scheme (KPCS) was ratified and signed by diamond-producing and diamond-importing countries. The goal of this study was to estimate the alluvial diamond resource endowment and the current production capacity of the alluvial diamond mining sector of Guinea. A modified volume and grade methodology was used to estimate the remaining diamond reserves within Guinea’s diamondiferous regions, while the diamond-production capacity of these zones was estimated by inputting the number of artisanal miners, the number of days artisans work per year, and the average grade of the deposits into a formulaic expression. Guinea’s resource potential was estimated to be approximately 40 million carats, while the production capacity was estimated to lie within a range of 480,000 to 720,000 carats per year. While preliminary results have been produced by integrating historical documents, five fieldwork campaigns, and remote sensing and GIS analysis, significant data gaps remain. The artisanal mining sector is dynamic and is affected by a variety of internal and external factors. Estimates of the number of artisans and deposit variables, such as grade, vary from site to site and from zone to zone. This report has been developed on the basis of the most detailed information available at this time. However, continued fieldwork and evaluation of artisanally mined deposits would increase the accuracy of the results.
DS200712-0213
2007
Mamantov, G.Dai, S., Young, J.P., Begun, G.M., Mamantov, G.Temperature measurement by observation of the Raman spectrum of diamond.Applied Spectroscopy, Vol. 46, 2, pp. 375-377.TechnologySpectroscopy
DS201012-0041
2010
Mambo, V.S.Bauer, F.U., Glasmacher, U.A., Malikwisha, M., Mambo, V.S., Mutete, B.V.The eastern Congo - a beauty spot, rediscovered from a geological point of view.Geology Today, Vol. 26, 2, pp. 55-64.Africa, Democratic Republic of CongoHistory
DS2003-0872
2003
Mambole, A.Mambole, A., Fleitout, L.Petrological layering induced by an endothermic phase transition in the Earth's mantleGeophysical Research Letters, Vol. 29, 22, Nov. 15, . DOI 10.1029/2002GLO14674MantlePetrology
DS1991-1043
1991
Mambwe, S.Mambwe, S.Gemstone Corporation of Zambia was created in April 1991Small Mining International, Bulletin, No. 4, February p. 6ZambiaNews item, Gemstones not specific to diamonds
DS1989-0924
1989
Mambwe, S.H.Mambwe, S.H.An investigation of the phosphate resources of Nkombwa Hill, carbonatitecomplex, in ZambiaZimco, MINEX seminar on Carbonatites and other igneous phosphate bearing, Held Feb. 1, 1989, 1pZambiaCarbonatite
DS1989-0925
1989
Mambwe, S.H.Mambwe, S.H.Investigation of the phosphate resources of NkombwaHill carbonatite, ZambiaZambian Journal of Applied Earth Sciences, Vol. 3, No. 1, August pp. 27-35ZambiaCarbonatite, Nkombwa Hill
DS1982-0390
1982
Mamchur, G.P.Mamchur, G.P.Abiogenic Hydrocarbon Synthesis in Kimberlite Pipes As Revealed by Isotope Distribution in Carbon.Doklady Academy of Science USSR, Earth Science Section., Vol. 252, No. 4, PP. 163-165.RussiaUdachnaya, Inclusions, Geochemistry
DS1986-0436
1986
Mamchur, G.P.Kharkiv, A.D., Serenko, V.P., Mamchur, G.P., Melnik, Yu.M.Carbon isotope composition of carbonates from deep horizons Of the Mirpipe.(Russian)Geochemistry International (Geokhimiya), (Russian), No. 3, pp. 304-310RussiaGeochronology, Carbonate
DS1988-0350
1988
Mamchur, G.P.Kharkiv, A.D., Boris, Ye.I., Shabo, Z.V., Mamchur, G.P., SheremeyevThe occurrence of oil in the eruptive pipes of theSiberianPlatform*(in Russian)Geologii i Geofiziki, (Russian), No. 4, pp. 60-70RussiaStructural geology, Tectonics
DS1992-1531
1992
Mamdani, E.H.Terano, T., Asai, K., Sugeno, M., Mamdani, E.H.Fuzzy systems theory and its applicationsNature, Vol. 359, No. 6398, October 29, p. 788GlobalComputer, Program - Fuzzy systems
DS1998-0789
1998
Mamontov, V.P.Korobeinikov, A.N., Mamontov, V.P., Pavlov, V.P.Geology and ore mineralization of the Salmagora alkaline ultrabasic pluton Kola Peninsula: new data.Doklady Academy of Sciences, Vol. 363, No. 8, Oct-Nov. pp. 1082-1085.Russia, Kola PeninsulaAlkaline rocks
DS2001-0725
2001
Man. Exploration and Mining ReviewMan. Exploration and Mining ReviewDiamonds.. brief 1/8p. summary of activityMan. Exploration and Mining Review, p. 16.ManitobaNews item, Diamond exploration
DS1997-0721
1997
Manaf, H.Manaf, H.Indonesia's mining policyDeveloping Indonesia-Canada Cooperation Nov.3-4, Jakarta, 21p. 4 page size mapsIndonesiaLegal - mining laws, policy, Mineral agreement, investment, contracts
DS1998-1024
1998
ManakovMitioukhine, S.I., Manakov, Poltaratskaya, RomanovNew dat a about the structure of the Earth's crust according to regional geophysical investigations.7th International Kimberlite Conference Abstract, pp. 606-8.Russia, YakutiaGeophysics - magnetotellurics, Geodynamics
DS2001-1013
2001
ManakovSarayev, A.L., Pertel, Garat, Manakov, AlexandrovPossibilities of magnetotellurics for kimberlite exploration in the Russian PlatformNorth Atlantic Minerals Symposium held May 27-30, pp. 149. abstract.RussiaGeophysics - magnetotellurics
DS200512-0935
2002
Manakov, A.B.Saraev, A.K., Pertel, M.I., Nikiforov, A.B., Garat, M.N., Manakov, A.B., Ingerov, O.I.Magnetotelluric exploration for kimberlite pipes in Yakutian Province, Sakha Republic, Russia.Phoenix Geophysics Preprint, English, Jan. 7p. text 17 figuresRussia, Siberia, YakutiaGeophysics - magnetotellurics, Almakinskaya, Mirensky
DS1987-0622
1987
Manakov, A.V.Romanov, N.N., Manakov, A.V.Possibilities of magnetic surveying in prospecting for kimberlite pipesSoviet Geology and Geophysics, Vol. 28, No. 12, pp. 66-70RussiaGeophysics
DS1988-0261
1988
Manakov, A.V.Gorev, N.I., Manakov, A.V., Ericnshek, I.M., Bardina, E.I., et al.Reflection of the Mirinskoe kimberlite field in the structure of sedimentary cover.(Russian)Doklady Academy of Sciences Akademy Nauk SSSR, (Russian), Vol. 303, No. 3, pp. 685-689RussiaStructure, Mirinskoe
DS1988-0262
1988
Manakov, A.V.Gorev, N.I., Manakov, A.V., Erincheck, Yu.M., et al.Structural reflection of the Mirnyy kimberlite field in the sedimentarycoverDokl. Acad. Sciences USSR Earth Science Section, Vol. 303, No. 6, pp. 77-80RussiaGeophysics, Structure, Mirnyy
DS1995-1154
1995
Manakov, A.V.Manakov, A.V.The structure of consolidated crust of the Yakutian diamondiferousprovince, N. part -geophysical evidenceProceedings of the Sixth International Kimberlite Conference Abstracts, pp. 348-349.Russia, YakutiaGeophysics, Deposit -Anabar, Olenyok River areas
DS200512-0344
2005
Manakov, A.V.Gladkov, A.S., Zinchuk, N.N, Bornyakov, S.A., Sherman, S.I., Manakov, A.V., Matrosov, V.A., Garat, DzyubaNew dat a on the internal structure and formation mechanism of kimberlite hosting fault zones in the Malaya Botuoba region, Yakutian Diamondiferous provinceDoklady Earth Sciences, Vol. 402, 4, pp. 520-23.Russia, YakutiaTectonics, structure, Malaya Botuoba
DS200512-0911
2002
Manakov, A.V.Rosen, O.M., Serenko, V.P., Spetsius, Z.V., Manakov, A.V., Zinchuk, N.N.Yakutian kimberlite province: position in the structure of the Siberian Craton and composition of the upper and lower crust.Russian Geology and Geophysics, Vol. 45, 1, pp. 1-24.Russia, SiberiaTectonics
DS200612-1176
2005
Manakov, A.V.Rosen, O.M., Manakov, A.V., Serenko, V.P.Paleoproterozoic collisional system and Diamondiferous lithospheric keel of the Yakutian kimberlite province.Russian Geology and Geophysics, Vol. 46, 12, pp. 1237-51.Russia, YakutiaTectonics
DS200612-1177
2005
Manakov, A.V.Rosen, O.M., Manakov, A.V., Suvorov, V.D.The collisional system in the northeastern Siberian Craton and a problem of diamond bearing lithospheric keel.Geotectonics, Vol. 39, 6, pp. 42-67.Russia, SiberiaTectonics
DS1998-0929
1998
Manatschal, G.Manatschal, G., Ulfbeck, D., Van Gool. J.Change from thrusting to syncollisional extension at a mid-crustal level:an example from the PaleoproterozoicCanadian Journal of Earth Sciences, Vol. 35, No. 7, July pp. 802-19.GreenlandOrogen - Nagssugtoquidian, Tectonics
DS1999-0349
1999
Manatschal, G.Kalsbeek, F., Manatschal, G.Geochemistry and tectonic significance of peridotitic and metakomatiitic rocks from Us suit area.Precambrian Research, Vol. 94, No. 1-2, Mar. pp. 101-120.GreenlandOrogeny - Nagssugtoqidian, Tectonics
DS2001-0248
2001
Manatschal, G.Desmurs, L., Manatschal, G., Bernouilli, D.The Steinmann trinity revisited: mantle exhumation and magmatism along the ocean continent transition:Geological Society of London, Special Publication, No. 187, pp. 235-66.Switzerland, EuropeMantle - Platta Nappe
DS200812-0545
2007
Manatschal, G.Karner, G.D., Manatschal, G., Pinheiro, L.M.Imaging, mapping and modelling continental lithosphere extension and breakup.New books, Tables of contents and costsGlobalTectonics, deformation
DS201805-0941
2018
Manatschal, G.Chenin, P., Picazo, S., Jammes, S., Manatschal, G., Muntener, O., Karner, G.Potential role of lithospheric mantle composition in the Wilson cycle: a North American perspective.Geological Society of London, Special Publication, Vol. 470, doi:10.1144 /SP470.10Mantlewilson cycle

Abstract: Although the Wilson cycle is usually considered in terms of wide oceans floored with normal oceanic crust, numerous orogens result from the closure of embryonic oceans. We discuss how orogenic and post-orogenic processes may be controlled by the size/maturity of the inverted basin. We focus on the role of lithospheric mantle in controlling deformation and the magmatic budget. We describe the physical properties (composition, density, rheology) of three types of mantle: inherited, fertilized and depleted oceanic mantle. By comparing these, we highlight that fertilized mantle underlying embryonic oceans is mechanically weaker, less dense and more fertile than other types of mantle. We suggest that orogens resulting from the closure of a narrow, immature extensional system are essentially controlled by mechanical processes without significant thermal and lithological modification. The underlying mantle is fertile and thus has a high potential for magma generation during subsequent tectonic events. Conversely, the thermal state and lithology of orogens resulting from the closure of a wide, mature ocean are largely modified by subduction-related arc magmatism. The underlying mantle wedge is depleted, which may inhibit magma generation during post-orogenic extension. These end-member considerations are supported by observations derived from the Western Europe-North Atlantic region.
DS1990-0978
1990
Manby, C.N.D.Manby, C.N.D., Wakeling, T.R.M.Developments in soft-ground drilling, sampling and in-situ testingTransactions of the Institute of Mining and Metallurgy (IMM), Vol. 99, Sect. A., pp. A91-109GlobalDrilling techniques, Methodology
DS1987-0432
1987
Mancheno, M.A.Mancheno, M.A., Ruiz Gomez, J.M.Mineralogy of lamproitic rocks associated wth Triassic diapirs in northeastern Murcia: statistics. *SPA.Eclogia (Madrid), *SPA., No. 1, pp. 47-53.GlobalLamproite
DS1990-0979
1990
Manchester, J.Manchester, J., Smith, D., Tyner, G.N.Chino Valley xenoliths: lower crust and upper mantle below the Colorado plateau transition zoneGeological Society of America (GSA) Abstracts with programs, Cordilleran, Vol. 22, No. 3, p. 63Colorado PlateauXenoliths, Chino Valley
DS1994-1631
1994
Manchester, J.E.Smith, D., Arculus, R.J., Manchester, J.E., Tyner, G.Garnet pyroxenite amphibole xenoliths from Chino Valley Arizona, And implications for continental lithosphere below the MohoJournal of Geophysical Research, Vol. 99, No. B 1, January 10, pp. 683-696ArizonaXenoliths
DS1994-1632
1994
Manchester, J.E.Smith, D., Arculus, R.J., Manchester, J.E., Tyner, G.N.Garnet pyroxene amphibole xenoliths from Chino Valley, Arizona, And implications for continental lithosphere below the mantle.Journal of Geophysical Research, Vol. 99, No. B 1, January 10, pp. 683-696.ArizonaXenoliths
DS1983-0431
1983
MancheteMancheteThe New Race for Diamond Is at PoxoreoIndiaqua., No. 36, 1983/3, PP. 27-28.Brazil, Mato GrossoCurrent Activites, History
DS201608-1421
2015
Manchuk, J.G.Manchuk, J.G., Stiefenhofer, J., Thurston, M., Deutsch, C.V.Framework for resource uncertainty prediction and dat a valuation: an application to diamond deposits. OrapaCanadian Institute of Mining and Metallurgy, Vol. 6, 3, 14p.Africa, BotswanaDeposit - Orapa

Abstract: The degree of uncertainty associated with a natural diamond resource is important to quantify from the time of discovery through the production lifetime. Data collection occurs during the discovery, exploration, delineation, and production or recovery phases. Quantifying the relationship between data and uncertainty is an important component of project valuation. The value of data is measured as their potential to reduce uncertainty if they are collected. A method is developed using Monte Carlo simulation for predicting resource uncertainty and valuing data during critical phases of development, particularly discovery and exploration. The technique is applied to diamond pipe deposits.
DS201712-2703
2017
Mancinelli, N.J.Mancinelli, N.J., Fischer, K.M., Dalton, C.A.How sharp is the cratonic lithosphere; asthenosphere transition?Geophysical Research Letters, Vol. 44, 20, pp. 10,189-10,197.Mantlecraton

Abstract: Earth's cratonic mantle lithosphere is distinguished by high seismic wave velocities that extend to depths greater than 200 km, but recent studies disagree on the magnitude and depth extent of the velocity gradient at their lower boundary. Here we analyze and model the frequency dependence of Sp waves to constrain the lithosphere-asthenosphere velocity gradient at long-lived stations on cratons in North America, Africa, Australia, and Eurasia. Beneath 33 of 44 stations, negative velocity gradients at depths greater than 150 km are less than a 2-3% velocity drop distributed over more than 80 km. In these regions the base of the typical cratonic lithosphere is gradual enough to be explained by a thermal transition. Vertically sharper lithosphere-asthenosphere transitions are permitted beneath 11 stations, but these zones are spatially intermittent. These results demonstrate that lithosphere-asthenosphere viscosity contrasts and coupling fundamentally differ between cratons and younger continents.
DS1998-0930
1998
Mancini, F.Mancini, F., Papunen, H., Savitoki, S., Marshall, B.EPMA analyses and X-ray single crystal refinements of garnets from Arkangelsk kimberlites, northwest Russia.Petrology, Vol. 6, No. 6, Nov-Dec. pp. 546-554.Russia, Arkangelsk, Kola PeninsulaCrystallography, Garnet morphology
DS2002-0990
2002
Mancini, F.Mancini, F., Harlow, G.E., Cahill, C.The crystal structure and cation ordering of phase... ( K and H bearing silicate phase in the mantle)American Mineralogist, Vol. 87, pp. 302-6.MantlePetrology - exprimental
DS2002-0991
2002
Mancini, F.Mancini, F., Harlowm G.E., Cahill, C.The crystal structure and cation ordering of phase .... a potential K and H bearing phase in the mantle.American Mineralogist, Vol.87, 2-3,,pp. 302-6.MantleMineralogy
DS200412-1745
2004
Mancini, L.Schena, G., Favretto, S., Santoro, L., Pasini, A., Bettuzzi, M., Casali, F., Mancini, L.Detecting microdiamonds in kimberlite drill hole cores by computed tomography.International Journal of Mineral Processing, 16p.TechnologyMineral processing - microdiamonds
DS201702-0209
2017
Mancini, L.H.De Oliveira, I.L., Brod, J.A., Cordeiro, P.F.O., Dantas, E.L., Mancini, L.H.Insights into the Late stage differentiation processes of the Cat alao I Carbonatite complex in Brazil: new Sr-Nd and C-O isotopic dat a in minerals from niobium ores.Lithos, In press available, 44p.South America, BrazilDeposit - Catalao I

Abstract: The Late Cretaceous Catalão I carbonatite complex consists of ultramafic silicate rocks, phoscorites, nelsonites and carbonatites. The latest stages of the evolution of the complex are characterized by several nelsonite (magnetite-apatite rock) and carbonatite dykes, plugs and veins crosscutting earlier alkaline rocks. The interaction between the latter and late-stage carbonatites and/or carbo-hydrothermal fluids, converted the original dunites and bebedourites to metasomatic phlogopitites. Late-stage nelsonites (N1), pseudonelsonites (N2) and various types of dolomite carbonatites (DC) including norsethite-, magnesite- and/or monazite-bearing varieties show significant whole-rock Nd and Sr isotopic variations. To elucidate whether magmatic or metasomatic processes, or both, were responsible for these isotope variations we characterized the Nd and Sr isotope compositions of major mineral phases (i.e. apatite, dolomite, norsethite, pyrochlore and tetraferriphlogopite) in these late-stage rocks. Mineral isotope data recorded the same differences observed between N1 and N2 whole-rocks with N2 minerals showing more enriched isotopic signatures than minerals from N1. Sr isotopic disequilibrium among minerals from N2 pseudonelsonites and spatially related dolomite carbonatite pockets implies formation from batches of carbonate melts with distinct isotopic compositions. A detailed investigation of Nd and Sr isotopes from whole-rocks and minerals suggests that the most evolved rocks of the Catalão I complex probably derive from two different evolution paths. We propose that an earlier magmatic trend (path A) could be explained by several batches of immiscible and/or residual melts derived from carbonated-silicate parental magma (e.g. phlogopite picrite) contaminated with continental crust to a variable extent, in an AFCLI-like process. A second trend (path B) comprises highly variable 143Nd/144Ndi at nearly constant 87Sr/86Sri coupled with high ?18O in carbonates. This is interpreted here as the result of the interaction of previously-formed dolomite carbonatites with carbo-hydrothermal fluids.
DS2001-0629
2001
Manckelow, N.S.Koyi, H.A., Manckelow, N.S.Tectonic modelling: a volume in honour of Hans RambergGeological Society of America Memoir, 280p.GlobalBook - table of contents, Tectonic - deformation
DS200812-0708
2008
Mancktelow, N.S.Mancktelow, N.S.Tectonic pressure: theoretical concepts and modelled examples.Lithos, Vol. 103, 1-2, pp. 149-177.MantleTectonics
DS1990-0494
1990
Mancuso, J.Frizado, J., Mancuso, J.FOXPET: a FOXBASE Mineralogical Association of Canada (MAC) database system for managing petrological information(IGBADAT)Geological Society of America (GSA) Annual Meeting, Abstracts, Vol. 22, No. 7, p. A152GlobalComputer Program, FOXPET- petrology
DS1995-1350
1995
Mancuso, J.D.Nielsen, R.L., Mancuso, J.D., Miller, R.A., Sabins, F.F.Use of thematic mapper imagery in generative mineral exploration Central Andes of South AmericaAmerican Institute of Mining, Metallurgical, and Petroleum Engineers (AIME) Preprint, No. 95-9, 4pChile, Peru, Ecuador, Argentina, BoliviaRemote sensing, Exploration technique
DS202112-1935
2021
Mandal, B.Kumar, P., Mandal, B., Kumar, M.P.Seismic structure of the crust and lithospheric mantle of the Indian Shield: a review.Journal of the Geological Society of India, Vol. 97, 10, pp. 1169-1189.Indiageophysics - seismics

Abstract: The article reviews the history and accomplishments of CSIR-NGRI over the past 60 years, related to elucidating the seismic structure of the crust and lithospheric mantle of the Indian shield. Extensive investigations have been carried out in diverse geological and tectonic provinces of India, employing seismic reflection, refraction/wide-angle reflection and passive seismology to decipher (a) the evolution of the Indian plate through geological time, (b) hazard and its mitigation and (c) accumulation and disposition of natural resources. These endeavours entailed the application and development of state-of-the-art methodologies. Synthesis of the results from active and passive seismology reveals that the thickness of the crust varies between 28 and 65 km in the Kachchh and Aravalli regions respectively, consistent with their evolutionary histories. The thickest crust is observed in the western Dharwar craton (WDC) and the shallowest lies in the west coast. The crust in the shield region is mostly thicker, while it is thin beneath the rift zones. Results from coincident reflection and wide-angle seismic reflection studies broadly suggest a three-layered crust with magmatic underplating. Interestingly, the seismic sections traversing the Aravalli fold belt, central Indian suture zone, Dharwar craton and Southern Granulite Terrain (SGT) depict paleo-collision and subduction environments. The diverse character of the Moho, crustal fabrics and structure in different geological provinces indicate that contrasting tectonic environments might have influenced their evolution and support the hypothesis that plate tectonic processes were operative since Neoarchean. The thickness of the lithosphere estimated from receiver functions varies from 80 to 140 km. An undulation in the Lithosphere Asthenosphere Boundary reveals evidence for a flexure on a regional scale, owing to the continental collision of the Indian and Asian plates. However, the lithospheric thickness derived from surface wave dispersion studies is somewhat larger, ranging from 100 to 250 km, with some body wave tomographic studies suggesting it to be ?400 km, in consonance with the concept of Tectosphere. The thickness values derived from both the methods agree at a few locales such as the Eastern Dharwar Craton, SGT, Cambay, Singhbhum and western DVP. However, a broad disagreement prevails in WDC and northern part of the Indian shield where surface wave tomography reveals the thickness of lithosphere to be 140 to 200 km.
DS1989-0926
1989
Mandal, N.Mandal, N., Chakraborty, C.Fault motion and curved slickenlines: a theoretical analysisJournal of Structural Geology, Vol. 11, No. 4, pp. 497-501. Database # 17970GlobalStructure-fault motion, Tectonics
DS1992-0988
1992
Mandal, N.Mandal, N., Khan, D., Krishna Deb, S.An experimental approach to wide necked pinch and swell structuresJournal of Structural Geology, Vol. 14, No. 4, pp. 395-403GlobalStructure, Pinch and swell
DS200412-0301
2003
Mandal, N.Chakaborty, C., Mandal, N., Ghosh, S.K.Kinematics of the Gondwana basins of peninsular India.Tectonophysics, Vol. 377, 1, pp. 299-324.IndiaTectonics
DS201312-0571
2012
Mandal, N.Mandal, N., Charavarty, K.H., Borah, K., Rai, S.S.Is a cation ordering transition of the Mg-Fe olivine phase in the mantle responsible for the shallow mantle seismic discontinuity beneath the Indian craton?Journal of Geophysical Research, 9225IndiaHales discontinuity
DS1999-0440
1999
Mandal, P.Mandal, P.Intraplate stress distribution induced by topography and crustal density heterogeneities beneath ...Tectonophysics, Vol. 302, No. 1-2, Feb. 15, pp. 159-India, South IndiaShield, Geophysics - geodynamics
DS202106-0943
2021
Mandal, P.Illa, B., Reshma, K.S., Kumar, P., Srinagesh, D., Haldar, C., Kumar, S., Mandal, P.Pn tomography and anisotropic study of the Indian Shield and the adjacent regions.Tectonophysics, Vo. 813, 228932 23p. PdfIndiatomography

Abstract: High-resolution P-wave velocity and anisotropy structure of the hitherto elusive uppermost mantle beneath the Indian shield and its surrounding regions are presented to unravel the tectonic imprints in the lithosphere. We inverted high quality 19,500 regional Pn phases from 172 seismological stations for 4780 earthquakes at a distance range of 2° to 15° with a mean apparent Pn velocity of 8.22 km/s. The results suggest that the Pn velocity anomalies with fast anisotropic directions are consistent with the collision environments in the Himalaya, Tibetan Plateau, Tarim Basin, and Burmese arc regions. The higher Pn anomalies along the Himalayan arc explicate the subducting cold Indian lithosphere. The cratonic upper mantle of the Indian shield is characterized by Pn velocity of 8.12-8.42 km/s, while the large part of the central Indian shield has higher mantle-lid velocity of ~8.42 km/s with dominant anisotropic value of 0.2-0.3 km/s (~7.5%) suggesting the presence of mafic ‘lava pillow’ related to the Deccan volcanism. The impressions of the rifts and the mobile belts are conspicuous in the velocity anomaly image indicating their deep seated origin. The Pn anisotropy in the Indian shield exhibits a complex pattern and deviates from the absolute plate motion directions derived from the SKS study, demonstrating the presence of frozen anisotropy in the Indian lithospheric uppermost mantle, due to the large scale tectonic deformation after its breakup from the Gondwanaland. Whereas, Pn and SKS anisotropic observations are well consistent in Tarim basin, Tibetan regions, eastern Himalayan syntaxis and the Burmese arc. The modeled anisotropic Pn clearly manifests a lower velocity anomaly bounded by 85°E and 90°E ridges in the southern Bay of Bengal. Further, 85°E ridge spatially separates the BoB lithosphere into faster and slower regions consistent with the body wave tomography and free-air gravity observation.
DS1998-0067
1998
MandarinoBailey, L.M., Helmstaedt, H.H., Peterson, R., MandarinoMicrodiamonds and indicator minerals from a talc schist rock, FrenchGuiana.7th International Kimberlite Conference Abstract, pp. 37-39.GlobalMetakimberlites, Paramaca series
DS2000-0610
2000
Mandea, M.Mandea, M., Bellanger, E., Le Mouel, J-L.A geomagnetic jerk for the end of the 20th. century?Earth and Planetary Science Letters, Vol.183, No.3-4, pp.369-73.GlobalGeophysics - magnetics
DS200712-0426
2007
Mandea, M.Hemant, K., Thebault, E., Mandea, M., Ravat, D., Maus, S.Magnetic anomaly map of the world: merging satellite, airborne, marine and ground based magnetic dat a sets.Earth and Planetary Science Letters, Vol. 260, 1-2, pp. 56-71.GlobalMap - magnetics
DS200712-0427
2007
Mandea, M.Hemant, K., Thebault, E., Mandea, M., Ravat, D., Maus, S.Magnetic anomaly map of the world: merging satellite, airborne, marine and ground based magnetic dat a sets.Earth and Planetary Science Letters, Vol. 260, 1-2, pp. 56-71.GlobalMap - magnetics
DS200812-0709
2007
Mandea, M.Mandea, M., Korte, M., Mozzoni, D., Kotze, P.The magnetic field changing over the southern African continent: a unique behaviour.South African Journal of Geology, Vol. 110, 2-3, Sept. pp. 193-202.Africa, South AfricaGeophysics - magnetics
DS1989-0927
1989
Mandelbrot, B.B.Mandelbrot, B.B.Multifractal measures, especially for the geophysicistPure and Applied Geophysics, Vol. 131, No. 1/2, pp. 5-42. Database # 18153GlobalFractal, Geophysics
DS200412-1214
2004
Mandel-Campbell, A.Mandel-Campbell, A.Rough trade - how the diamond bonanza is changing the North and turning an industry inside out.The Walrus, Vol. 1, 4, April/May, pp. 36-49.Canada, Northwest TerritoriesOverview - profile
DS2003-1085
2003
Mandeville, C.Platt, J.P., Allerton, S., Kirker, A., Mandeville, C., Mayfield, D.The ultimate arc: differential displacement, oroclinal bending..Tectonics, Vol. 22,3,May, 10.1029/2001TC001321GlobalTectonics - arc
DS200412-1556
2003
Mandeville, C.Platt, J.P., Allerton, S., Kirker, A., Mandeville, C., Mayfield, D.The ultimate arc: differential displacement, oroclinal bending...Tectonics, Vol. 22,3,May, 10.1029/2001 TC001321TechnologyTectonics - arc
DS1988-0436
1988
Mandl, G.Mandl, G.Mechanics of tectonic faulting- models and basic conceptsElsevier, Developments in Structural Geology No. 1, 405pBookStructure, Fault, thrust
DS1982-0391
1982
Mandler, H.Mandler, H.Diamonds in PhilatelyIndiaqua., No. 33, PP. 79-82.GlobalBlank
DS1997-0722
1997
Mandler, H.A.F.Mandler, H.A.F., Clowes, R.M.Evidence for extensive tabular intrusions in the Precambrian shield Of western Canada: 160 km sequenceGeology, Vol. 25, No. 3, March pp. 271-274.Alberta, SaskatchewanTrans Hudson Orogeny, Geophysics - seismics
DS1998-0931
1998
Mandler, H.A.F.Mandler, H.A.F., Clowes, R.M.The HSI bright reflector: further evidence for extensive magmatism in the Precambrian western Canada.Tectonophysics, Vol. 288, No. 1-4, Mar. pp. 71-82.British Columbia, Alberta, SaskatchewanTectonics, Geophysics - seismic
DS1996-0876
1996
Mandryk, C.A.S.Mandryk, C.A.S.Late Wisconsi nan deglaciation of Alberta: processes and paleogeographyQuaternary International, Vol. 32, pp. 79-85.AlbertaGeomorphology
DS201511-1877
2015
Mane, S.Sastry, M.D., Mane, S., Gaonkar, M., Bhide, M.K., Desai, S.N., Ramachandran, K.T.Luminescence studies of gemstones and diamonds.International Journal of Luminescence and Applications, Vol. 5, 3, pp. 293-297.TechnologyLuminescence

Abstract: Some of the minerals like Corundum, chryso beryl, beryllium alumino silicate (emerald) and also Diamond exhibit exceptional optical properties[1] and in some cases attractive colours; in India these were recognized quite early since the days of Indus valley civilization. In more recent times there has been a lot of scientific interest in colours and colour modifications in Gem minerals and in Diamonds. Science of gem stones deals with their identification by non destructive means and understanding of origin of colour and excellent optical properties[1]. Optical methods have long been used to obtain properties like ‘Refractive Index’ which still remains an important parameter as a preliminary test to identify the gemstone/mineral. The spectroscopic studies of gem grade minerals are essentially directed towards some of these features in identifying and understanding the spectral properties of chromophores, either chemical impurities and/or radiation induced point defects, in solids. In this context a variety of spectroscopic methods are used to address the problems of the Gem stone identification and identification of origin of colours and colour modification treatments. The methods frequently used in Gem testing labs are the following: (i)Electronic absorption in UV-Visible-NIR range.(ii)UV-Vis excited luminescence, (iii) Vibrational spectra – Absorption in the Infra red range (iv) Vibrational spectra using Light Scattering (Raman spectroscopy) (v)Surface Fluorescence mapping Under deep UV excitation. The present paper deals with the luminescence studies in rubies, sapphires, emeralds and diamonds. Special mention may be made of fluorescence mapping using deep UV excitation (around 205 nm) corresponding to the band gap of diamond. Under such an excitation inter band excitation takes place creating a e-h pair and most of the absorption and subsequent emission being restricted to the surface. This makes surface mapping possible and thereby elucidating the growth patterns. This is invaluable in the diagnostics for the detection of synthetic diamonds. In this introductory presentation on the Luminescence methods in Gemmology, we give a brief account of optical spectroscopic methods which mainly deal with identification of corundum based gem stones (rubies, sapphire) and diamonds including the electronic absorption and luminescence of chromophore centres. In gem testing infrared absorption and Raman scattering methods are main work horses and they will be brought in as and when necessary to give a complete picture.
DS200712-0678
2007
Manea, V.Manea, V., Gurnis, M.Subduction zone evolution and low viscosity wedges and channels.Earth and Planetary Science Letters, Vol. 264, 1-2, pp. 22-45.MantleSubduction
DS201505-0237
2014
Maneck, M.Majka, J., Rosen, A., Janak, M., Froitzheim, N., Klonowska, I., Maneck, M., Sasinkova, V., Yoshida, K.Microdiamond discovered in the Seve Nappe (Scandinavian Caledonides) and its exhumation by the "vacuum-cleaner" mechanism.Geology, Vol. 42, 12, pp. 1107-110.EuropeMicrodiamonds
DS201502-0076
2014
Manecki, M.Majka, J., Rosen, A., Janak, M., Froitzheim, N., Klonowska, I., Manecki, M., Sasinkova, V., Yoshida, K.Microdiamond discovered in the Seve Nappe ( Scandinavian Caledonides) and its exhumation by the "vacuum-cleaner" mechanism.Geology, Vol. 42, 12, pp. 1107-1110.Europe, SwedenSubduction, microdiamond
DS1992-0295
1992
Manetti, P.Conticelli, S., Manetti, P., Menichet..S.Mineralogy, geochemistry and SR-isotopes in orendites from South Italy -constraints on their genesis and evolutionEuropean Journal of Mineralogy, Vol. 4, No. 6, Nov-Dec. pp. 1359-1375ItalyOrendites, Genesis
DS2003-0287
2003
Manetti, P.Corti, G., Bonini, M., Continelli, S., Innocenti, F., Manetti, P., Sokouris, D.Analogue modelling of continental extension: a review focused on the relations betweenEarth Science Reviews, Vol. 63, No. 3-4, pp. 169-247.MantleMagmatism, tectonics
DS200412-0373
2003
Manetti, P.Corti, G., Bonini, M., Continelli, S., Innocenti, F., Manetti, P., Sokouris, D.Analogue modelling of continental extension: a review focused on the relations between the patterns of deformation and the preseEarth Science Reviews, Vol. 63, no. 3-4, pp. 169-247.MantleMagmatism, tectonics
DS200412-0374
2004
Manetti, P.Corti, G., Bonini, M., Sokoutis, D., innocenti, F., Manetti, P., Cloetingh, S., Mulugeta, G.Continental rift architecture and patterns of magma migration: a dynamic analysis based on centrifuge models.Tectonics, Vol. 23, 2, TC2012 10.1029/2003 TC001561MantleGeodynamics
DS200512-1095
2005
Manetti, P.Tonarini, S., Agostini, S., Innocent, F., Manetti, P.d11B as tracer of slab dehydration and mantle evolution in western Anatolia Cenozoic magmatism.Terra Nova, Vol. 17, 3, pp. 259-264.MantleMagmatism - not specific to diamonds
DS200712-1012
2007
Manetti, P.Sokoutis, D., Corti, G., Bonin, M., Brun, J.P., Cloetingh, S., Maudit, T., Manetti, P.Modelling the extension of heterogeneous hot lithosphere.Tectonophysics, Vol. 444, pp. 63-79.MantleRheology, back arc extension
DS1997-0210
1997
Manetti, P. CioniConticelli, S., Francala, L., Manetti, P. Cioni, R.Petrology and geochemistry of the ultrapotassic rocks from the SabatiniJournal of Volcanology, Vol. 75, No. 1-2 Jan. pp. 107-136.ItalyUltrapotassic, Magma
DS202012-2227
2013
Manfredi, T.K.Manfredi, T.K., Nes, A.C.B., Perceira, V.P., Barbanson, L.The parasite-(Ce) mineralization associated with the Fazenda Varela carbonatite ( Correia Pinto, SC).Pesquisas Geosciencias, Dec. 14p. PdfSouth America, Brazil, Santa Catarinadeposit - Fazenda

Abstract: The Fazenda Varela carbonatite is part of the Lages alkaline complex (Late Cretaceous). The carbonatite occurs as abundant veins that cut the sandstones of the Rio Bonito Formation which are strongly brecciated and metasomatized. Petrography, geochemistry, X-ray diffraction, scanning electron microscopy and electron microprobe data allowed the identification and classification of REE fluorcarbonates. The carbonatite is composed essentially by ankerite and Fe-dolomite and was strongly affected for tardi and post magmatic events. The hydrothermal fluids percolated through fractures and grain boundaries and formed hydrothermal domains composed of barite, apatite, quartz, calcite, Fe-dolomite, and parisite-(Ce). In these domains, parisite-(Ce) occurs as well-developed fibrous to fibroradiated crystals. Parisite-(Ce) also occurs in hydrothermal veins that cut the metasomatized host rock. The parisite-(Ce) crystals are heterogeneous, occur in syntaxial growth with synchysite-(Ce), and have excess of Ca and REE and F depletions in relation to an ideal composition. The parasite-(Ce) mineralization formed from a fluid with low F activity that interacted with the rock and leached preferentially the LREE, which were likely transported as chlorine complexes.
DS2003-1101
2003
Manfredotti, C.Pratesi, G., Lo Giudice, A., Vishnevky, S., Manfredotti, C., Cipriani, C.Cathodluminescence investigations on the Popigai Ries and Lappajarvi impactAmerican Mineralogist, Vol. 88, pp. 1778-87.Russia, Siberia, FinlandMeteorite
DS200412-1577
2003
Manfredotti, C.Pratesi, G., Lo Giudice, A., Vishnevky, S., Manfredotti, C., Cipriani, C.Cathodluminescence investigations on the Popigai Ries and Lappajarvi impact diamonds.American Mineralogist, Vol. 88, pp. 1778-87.Russia, Siberia, Baltic ShieldMeteorite
DS2003-0873
2003
Mang, R.A.Mang, R.A.Hot ice... Canadian diamondsResource Magazine, Mining Association supplement, August, 3p.Northwest TerritoriesNews item
DS200412-1215
2003
Mang, R.A.Mang, R.A.Hot ice... Canadian diamonds.Resource World Magazine, August, 3p.Canada, Northwest TerritoriesNews item
DS1992-0989
1992
Manga, M.Manga, M., O'Connell, R.J., Stone, H.A.Effect of boundaries and compositional layering in the mantle on the ascent of mantle plumesEos Transactions, Vol. 73, No. 14, April 7, supplement abstracts p. 297MantlePlumes
DS1996-0841
1996
Manga, M.Li, X., Manga, M., Jeanloz, R.Temperature distribution in the laser heated diamond cell with externalheating, and implications perovskiteGeophysical Research Letters, Vol. 23, No. 25, Dec. 15, pp. 3775-3778.GlobalPerovskite
DS1997-0723
1997
Manga, M.Manga, M.Interactions between mantle diapirsGeophysical Research Letters, Vol. 24, No. 15, Aug. 1, pp. 1871-4.MantleDiapirs, Plumes
DS1997-0724
1997
Manga, M.Manga, M., Jeanloz, R.Thermal conductivity of corundum and periclase and implications for the lower mantle.Journal of Geophysical Research, Vol. 102, No. 2, Feb. 10, pp. 2799-3008.MantleGeothermometry
DS2001-1026
2001
Manga, M.Schaeffer, N., Manga, M.Interaction of rising and sinking mantle plumesGeophysical Research Letters, Vol. 28, No. 3, Feb. 1, pp.455-8.MantlePlumes, hotspots
DS2002-0592
2002
Manga, M.Gonnermann, H.M., Manga, M., Jellinek, A.M.Dynamics and longevity of an initially stratified mantleGeophysical Research Letters, Vol. 29,10,May15,pp.33-MantleGeodynamics
DS2002-0774
2002
Manga, M.Jellinek, A.M., Lenardic, A., Manga, M.The influence of interior mantle temperature on the structure of plumes: heads for Venus, tails for Earth.Geophysical Research Letters, Vol. 29, 10, DOI 10.1029/2001GL014624MantleHot spots, plumes
DS2002-0775
2002
Manga, M.Jellinek, A.M., Manga, M.The influence of a chemical boundary layer on the fixity, spacing and life time of mantle plumes.Nature, Vol. 418, Aug. 15, pp. 760-763.MantleHotposts, Geophysics - seismics
DS2003-0325
2003
Manga, M.De Paolo, D.J., Manga, M.Deep origin of hotspots - the mantle plume modelScience, Vol. 300, 5621, May 9, p. 920.MantleSubduction, Hotspot
DS200412-0426
2003
Manga, M.De Paolo, D.J., Manga, M.Deep origin of hotspots - the mantle plume model.Science, Vol. 300, 5621, May 9, p. 920.MantleSubduction
DS200412-0691
2004
Manga, M.Gonnermann, H.M., Jellinek, A.M., Richards, M.A., Manga, M.Modulation of mantle plumes and heat flow at the core mantle boundary by plate scale flow: results from laboratory experiments.Earth and Planetary Science Letters, Vol. 226, 1-2, pp. 53-67.MantleGeothermometry, boundary
DS200512-0476
2004
Manga, M.Jellinek, A.M., Manga, M.Links between long lived hot spots, mantle plumes, D' and plate tectonics.Reviews of Geophysics, Vol. 42, 3, RG3002MantleTectonics
DS200512-0618
2005
Manga, M.Lenardic, A., Moresi, L.N., Jellinek, A.M., Manga, M.Continental insulation, mantle cooling, and the surface area of oceans and continents.Earth and Planetary Science Letters, Vol. 234, 3-4, pp. 317-333.MantleGeothermometry
DS200512-0913
2005
Manga, M.Rost, S., Garnero, E.J., Williams, Q., Manga, M.Seismological constraints on a possible plume root at the core mantle boundary.Nature, No. 7042, June 2, pp. 666-669.MantleGeophysics - seismics
DS201312-0397
2014
Manga, M.Carlson, R.W., Garnero, E., Harrison, T.M., Li, J., Manga, M., McDonough, W.F., Mukhopadhyay, S., Romanowicz, B., Rubie, D., Williams, Q., Zhong, S.Deep time: how did the early Earth become our modern world?Annual Review of Earth and Planetary Sciences, Vol. 42, pp. 151-178.MantleConvection, composition
DS201412-0100
2014
Manga, M.Carlson, R.W., Garnero, E., Harrison, T.M., Li, J., Manga, M., McDonough, W.F., Mukhopadhyay, S., Romanowicz, B., Rubie, D., Williams, Q., Zhong, S.How did early Earth become our modern world?Annual Review of Earth and Planetary Sciences, Vol. 42, pp. 151-178.MantleMelting
DS201606-1130
2016
Manga, M.Zhang, Z., Dorfman, S.M., Labidi, J., Zhang, S., Li, M., Manga, M., Stixrude, L., McDonough, W.F., Williams, Q.Primordial metallic melt in the deep mantle.Geophysical Research Letters, Vol. 43, 8, pp. 3693-3697.MantleMelting

Abstract: Seismic tomography models reveal two large low shear velocity provinces (LLSVPs) that identify large-scale variations in temperature and composition in the deep mantle. Other characteristics include elevated density, elevated bulk sound speed, and sharp boundaries. We show that properties of LLSVPs can be explained by the presence of small quantities (0.3-3%) of suspended, dense Fe-Ni-S liquid. Trapping of metallic liquid is demonstrated to be likely during the crystallization of a dense basal magma ocean, and retention of such melts is consistent with currently available experimental constraints. Calculated seismic velocities and densities of lower mantle material containing low-abundance metallic liquids match the observed LLSVP properties. Small quantities of metallic liquids trapped at depth provide a natural explanation for primitive noble gas signatures in plume-related magmas. Our model hence provides a mechanism for generating large-scale chemical heterogeneities in Earth's early history and makes clear predictions for future tests of our hypothesis.
DS201607-1323
2016
Manga, M.Zhang, Z., Dorfman, S.M., Labidi, J., Zhang, S., Li, M., Manga, M., Stixrude, L., McDonough, W.F., Williams, Q.Primordial metallic melt in the deep mantle.Geophysical Research Letters, Vol. 43, 8, pp. 3693-3699.MantleMelting

Abstract: Seismic tomography models reveal two large low shear velocity provinces (LLSVPs) that identify large-scale variations in temperature and composition in the deep mantle. Other characteristics include elevated density, elevated bulk sound speed, and sharp boundaries. We show that properties of LLSVPs can be explained by the presence of small quantities (0.3 -3%) of suspended, dense Fe-Ni-S liquid. Trapping of metallic liquid is demonstrated to be likely during the crystallization of a dense basal magma ocean, and retention of such melts is consistent with currently available experimental constraints. Calculated seismic velocities and densities of lower mantle material containing low-abundance metallic liquids match the observed LLSVP properties. Small quantities of metallic liquids trapped at depth provide a natural explanation for primitive noble gas signatures in plume-related magmas. Our model hence provides a mechanism for generating large-scale chemical heterogeneities in Earth's early history and makes clear predictions for future tests of our hypothesis.
DS2000-0611
2000
Mangan, M.Mangan, M., Sisson, T.Delayed, disequilibrium degassing in rhyolite magma: decompression experiments and implications explosive ..Earth and Planetary Science Letters, Vol.183, No.3-4, pp.441-55.GlobalMagmatism - volcanism, pipes not specific to diamonds
DS202112-1940
2021
Mangana, S.Mangana, S.A glimmer of Hope: a look at the World's most famous blue diamond.GIA Knowledge session, Nov. 18, youtube.comIndia, globalHistory - Hope diamond, famous diamond

Abstract: The Hope diamond is perhaps the most famous jewel in the world. In addition to its illustrious royal provenance, it is a rare marvel of nature due to its size, blue color and red phosphorescence. Follow Senior Manager of Diamond Identification Dr. Sally Magaña as she delves through both the history and recent scientific discoveries surrounding this gem.
DS1993-0966
1993
Mangas, J.Mangas, J., et al.Alkaline and carbonatitic intrusive complexes from Fuerteventura (CanaryIslands): radiometric exploration, chemical composition and stable isotope.Rare earth Minerals: chemistry, origin and ore deposits, International Geological Correlation Programme (IGCP) Project, pp. 79-80. abstractGlobalCarbonatite, Alkaline rocks
DS1993-0967
1993
Mangas, J.Mangas, J., Perez-Torrado, F.J., Reguilon, R., Martin-Izard, A.Geological characteristics of alkaline rocks and carbonatites of Fuerteventura (Canary Islands, Spain) and their rare earth elements (REE) ore potential.Terra Abstracts, IAGOD International Symposium on mineralization related to mafic, Vol. 5, No. 3, abstract supplement p. 32.GlobalCarbonatite
DS201312-0121
2013
Mangas, J.Campeny, M., Kamenetsky, V., Melgarejo, J.C., Mangas, J., Bambi, A., Manuel, J.CatAnd a carbonatitic lavas ( Angola): melt inclusion evidence.Goldschmidt 2013, AbstractAfrica, AngolaCarbonatite
DS201312-0122
2013
Mangas, J.Campeny, M., Kamenetsky, V., Melgarejo, J.C., Mangas, J., Bambi, A., Manuel, J.Sodium rich magmas parental to CatAnd a carbonatitic lavas ( Angola): melt inclusion evidence.Goldschmidt 2013, AbstractAfrica, AngolaCarbonatite
DS201412-0096
2014
Mangas, J.Campeny, M., Mangas, J., Melgarejo, J.C., Bambi, A., Alfonso, P., Gernon, T., Manuel, J.The Catanga extrusive carbonatites ( Kwanza Sul, Angola): an example of explosive carbonatitic volcanism.Bulletin of Volcanology, Vol. 76, pp. 818-Africa, AngolaCarbonatite
DS201509-0387
2015
Mangas, J.Campeny, M., Kamenetsky, V.S., Melgarejo, J.C., Mangas, J., Manuel, J., Alfonso, P., Kamenetsky, M.B., Bambi, A.C.J.M., Goncalves, A.O.Carbonatitic lavas in CatAnd a ( Kwanza Sul, Angola): mineralogical and geochemical constraints on the parental melt.Lithos, Vol. 232, pp. 1-11.Africa, AngolaCarbonatite

Abstract: A set of small volcanic edifices with tuff ring and maar morphologies occur in the Catanda area, which is the only locality with extrusive carbonatites reported in Angola. Four outcrops of carbonatite lavas have been identified in this region and considering the mineralogical, textural and compositional features, we classify them as: silicocarbonatites (1), calciocarbonatites (2) and secondary calciocarbonatites produced by the alteration of primary natrocarbonatites (3). Even with their differences, we interpret these lava types as having been a single carbonatite suite related to the same parental magma. We have also estimated the composition of the parental magma from a study of melt inclusions hosted in magnetite microphenocrysts from all of these lavas. Melt inclusions revealed the presence of 13 different alkali-rich phases (e.g., nyerereite, shortite, halite and sylvite) that argues for an alkaline composition of the Catanda parental melts. Mineralogical, textural, compositional and isotopic features of some Catanda lavas are also similar to those described in altered natrocarbonatite localities worldwide such as Tinderet or Kerimasi, leading to our conclusion that the formation of some Catanda calciocarbonatite lavas was related to the occurrence of natrocarbonatite volcanism in this area. On the other hand, silicocarbonatite lavas, which are enriched in periclase, present very different mineralogical, compositional and isotopic features in comparison to the rest of Catanda lavas. We conclude that its formation was probably related to the decarbonation of primary dolomite bearing carbonatites.
DS201801-0017
2017
Mangas, J.Giuliani, A., Campeny, M., Kamenetsky, V.S., Afonso, J.C., Maas, R., Melgarejo, J.C., Kohn, B.P., Matchen, E.L., Mangas, J., Goncalves, A.O., Manuel, J.Southwestern Africa on the burner: Pleistocene carbonatite volcanism linked to deep mantle upwelling in Angola.Geology, Vol. 45, 11, pp. 971=974.Africa, Angolacarbonatite - Catanda

Abstract: The origin of intraplate carbonatitic to alkaline volcanism in Africa is controversial. A tectonic control, i.e., decompression melting associated with far-field stress, is suggested by correlation with lithospheric sutures, repeated magmatic cycles in the same areas over several million years, synchronicity across the plate, and lack of clear age progression patterns. Conversely, a dominant role for mantle convection is supported by the coincidence of Cenozoic volcanism with regions of lithospheric uplift, positive free-air gravity anomalies, and slow seismic velocities. To improve constraints on the genesis of African volcanism, here we report the first radiometric and isotopic results for the Catanda complex, which hosts the only extrusive carbonatites in Angola. Apatite (U-Th-Sm)/He and phlogopite 40Ar/39Ar ages of Catanda aillikite lavas indicate eruption at ca. 500-800 ka, more than 100 m.y. after emplacement of abundant kimberlites and carbonatites in this region. The lavas share similar high-? (HIMU)-like Sr-Nd-Pb-Hf isotope compositions with other young mantle-derived volcanics from Africa (e.g., Northern Kenya Rift; Cameroon Line). The position of the Catanda complex in the Lucapa corridor, a long-lived extensional structure, suggests a possible tectonic control for the volcanism. The complex is also located on the Bié Dome, a broad region of fast Pleistocene uplift attributed to mantle upwelling. Seismic tomography models indicate convection of deep hot material beneath regions of active volcanism in Africa, including a large area encompassing Angola and northern Namibia. This is strong evidence that intraplate late Cenozoic volcanism, including the Catanda complex, resulted from the interplay between mantle convection and preexisting lithospheric heterogeneities.
DS201910-2284
2019
Mangas, J.Menendez, I., Campeny, M., Quevedo-Gonzalez, L., Mangas, J., Llovet, X., Tauler, E., Barron, V., Torrent, J., Mendez-Ramos, J.Distribution of REE-bearing minerals in felsic magmatic rocks and palesols from Gran Canaria, Spain: intraplate oceanic islands as a new example of potential, non-conventional sources of rare earth elements.Journal of Geochemical Exploration, Vol. 204, pp. 270-288.Europe, SpainREE

Abstract: Gran Canaria is a hotspot-derived, intraplate, oceanic island, comprising a variety of alkaline felsic magmatic rocks (i.e. phonolites, trachytes, rhyolites and syenites). These rocks are enriched in rare-earth elements (REE) in relation to the mean concentration in the Earth's crust and they are subsequently mobilised and redistributed in the soil profile. From a set of 57 samples of felsic rocks and 12 samples from three paleosol profiles, we assess the concentration and mobility of REE. In the saprolite that developed over the rhyolites, we identified REE-bearing minerals such as primary monazite-(Ce), as well as secondary phases associated with the edaphic weathering, such as rhabdophane-(Ce) and LREE oxides. The averaged concentration of REE in the alkaline bedrock varies from trachytes (449?mg?kg?1), to rhyolites (588?mg?kg?1) and to phonolites (1036?mg?kg?1). REE are slightly enriched in saprolites developed on trachyte (498?mg?kg?1), rhyolite (601?mg?kg?1) and phonolite (1171?mg?kg?1) bedrocks. However, B-horizons of paleosols from trachytes and phonolites showed REE depletion (436 and 994?mg?kg?1, respectively), whereas a marked enrichment was found in soils developed on rhyolites (1584?mg?kg?1). According to our results, REE resources on Gran Canaria are significant, especially in Miocene alkaline felsic magmatic rocks (declining stage) and their associated paleosols. We estimate a total material volume of approximately 1000?km3 with REE concentrations of 672?±?296?mg?kg?1, yttrium contents of 57?±?30?mg?kg?1, and light and heavy REE ratios (LREE/HREE) of 17?±?6. This mineralisation can be considered as bulk tonnage and low-grade ore REE deposits but it remains necessary to develop detailed mineral exploration on selected insular zones in the future, without undermining environmental and socioeconomic interests.
DS200612-0200
2006
Mangasini, F.Burnard, P., Basset, R., Marty, B., Fischer, T., Palhol, F., Mangasini, F., Makene, C.Xe isotopes in carbonatites: Oldonyo Lengai, East African Rift.Geochimica et Cosmochimica Acta, Vol. 70, 18, p. 1, abstract only.Africa, TanzaniaCarbonatite
DS201312-0200
2013
Mangasini, F.De Moor, M., Fischer, T.P., King, P.L., Botcharnikov, R.E., Hervig, R.L., Hilton, D.R., Barry, P.H., Mangasini, F., Ramirez, C.Volatile rich silicate melts from Oldoinyo Lengai volcano (Tanzania): implications for carbonatite genesis and eruptive behavior.Earth and Planetary Science Letters, Vol. 361, pp. 379-390.Africa, TanzaniaDeposit - Oldoinyo Lengai
DS201607-1284
2016
Mangasini, F.Baudouin, C., Parat, F., Denis, C.M.M., Mangasini, F.Nephelinite lavas at early stage of rift inititian ( Hanang volcano) North Tanzanian Divergence.Contributions to Mineralogy and Petrology, Vol. 171, 7, 20p.Africa, TanzaniaTectonics

Abstract: North Tanzanian Divergence is the first stage of continental break-up of East African Rift (<6 Ma) and is one of the most concentrated areas of carbonatite magmatism on Earth, with singular Oldoinyo Lengai and Kerimasi volcanoes. Hanang volcano is the southernmost volcano in the North Tanzanian Divergence and the earliest stage of rift initiation. Hanang volcano erupted silica-undersaturated alkaline lavas with zoned clinopyroxene, nepheline, andradite-schorlomite, titanite, apatite, and pyrrhotite. Lavas are low MgO-nephelinite with low Mg# and high silica content (Mg# = 22.4–35.2, SiO2 = 44.2–46.7 wt%, respectively), high incompatible element concentrations (e.g. REE, Ba, Sr) and display Nb–Ta fractionation (Nb/Ta = 36–61). Major elements of whole rock are consistent with magmatic differentiation by fractional crystallization from a parental melt with melilititic composition. Although fractional crystallization occurred at 9–12 km and can be considered as an important process leading to nephelinite magma, the complex zonation of cpx (e.g. abrupt change of Mg#, Nb/Ta, and H2O) and trace element patterns of nephelinites recorded magmatic differentiation involving open system with carbonate–silicate immiscibility and primary melilititic melt replenishment. The low water content of clinopyroxene (3–25 ppm wt. H2O) indicates that at least 0.3 wt% H2O was present at depth during carbonate-rich nephelinite crystallization at 340–640 MPa and 1050–1100 °C. Mg-poor nephelinites from Hanang represent an early stage of the evolution path towards carbonatitic magmatism as observed in Oldoinyo Lengai. Paragenesis and geochemistry of Hanang nephelinites require the presence of CO2-rich melilititic liquid in the southern part of North Tanzanian Divergence and carbonate-rich melt percolations after deep partial melting of CO2-rich oxidized mantle source.
DS1991-1044
1991
Mange, M.A.Mange, M.A., Maurer, H.F.W.Heavy minerals in colourCambridge University Press, 200p. approx. $ 90.00GlobalHeavy minerals, Descriptive -not specific to diamonds
DS1987-0433
1987
Manger, W.L.Manger, W.L.Arkansaw geologists: a brief historyThe Compass of Sigma Gamma Epsilon, University of of Arkansaw Special issue, Vol. 65, No. 4, Summer pp. 232-241ArkansasHistory
DS201807-1535
2018
Mangera, R.Voigt, A., Morrison, G., Hill, G., Dellas, G., Mangera, R.The application of XRT in the De Beers Group of Companies. Jwaneng, marineSAIMM Diamonds - source to use 2018 Conference 'thriving in changing times'. June 11-13., pp. 173-184.Africa, Botswana, NamibiaXRT sorters
DS201808-1795
2018
Mangera, R.Voight, A., Morrison, G., Hill, G., Dellas, G., Mangera, R.The application of XRT in the De Beers Group of Companies. PresentationSAIMM Diamonds - source to use 2018 Conference 'thriving in changing times'. June 11-13., 25 ppts.GlobalMining - XRT
DS201212-0517
2012
Manghnani, M.Nestola, F., Merli, M., Nimis, P., Parisatto, M., Kopylova, M., DE Stefano, A., Longo, M., Ziberna, L., Manghnani, M.In situ analysis of garnet inclusion in diamond using single crystal X-ray diffraction and X-ray micro-tomography.European Journal of Mineralogy, Vol. 24, 4, pp. 599-606.TechnologyTomography
DS1991-1536
1991
Manghnani, M.H.Secco, R.A., Manghnani, M.H., Teleching LiuVelocities and compressibilities of komatiitic meltsGeophysical Research Letters, Vol. 18, No. 8, August pp. 1397-1400GlobalKomatiite, Experimental petrology
DS1998-0932
1998
Manghnani, M.H.Manghnani, M.H., Yagi, T.Properties of earth and planetary materials at high pressure andtemperature.American Geophysical Union (AGU) Geophys. Monograph., No. 101, 558p. $ 90.00MantleSeperate articles cited of interest
DS201112-0315
2011
Manghnani, M.H.Fedortchouk, Y., Manghnani, M.H., Hushur, A., Shiryaev, A., Nestola, F.An atomic force microscopy study of diamond dissolution features: the effect of H2O and CO2 in the fluid on diamond morphology.American Mineralogist, Vol. 96, pp. 1768-1775.TechnologyDiamond resorption
DS201112-0732
2011
Manghnani, M.H.Nestola, F., Nimis, P., Ziberna, L., Longo, M., Marzoli, A., Harris, J.W., Manghnani, M.H., Fedortchuk, Y.First crystal structure determination of olivine in diamond: composition and implications for provenance in the Earth's mantle.Earth and Planetary Science Letters, Vol. 305, 1-2, pp. 249-255.MantleInclusion - olivine in diamond
DS1860-0156
1871
Mangin, A.Mangin, A.Pierres et MetauxTours: Alfred Mame Et Fils., 388P.GlobalGemology
DS201412-0545
2014
Mangler, M.F.Mangler, M.F., Marks, M.A.W., Zaitsev, A.N., Eby, G.N., Markl, G.Halogens (F, Cl and Br) at Oldoinyo Lengai volcano ( Tanzania): effects of magmatic differentiation, silicate, natrocarbonatite melt seperation and surface alteration of natrocarbonatite.Chemical Geology, Vol. 365, pp. 43-53.Africa, TanzaniaCarbonatite
DS1991-1045
1991
Manglik, A.Manglik, A., Singh, R.N.Rheology of Indian continental crust and upper mantleProceedings Indian Academy of Sciences, Earth and Planetary Sciences, Vol. 100, No. 4, December pp. 389-398IndiaMantle, Crust
DS1992-0990
1992
Manglik, A.Manglik, A., Singh, R.N.Rheological thickness and strength of the Indian continental lithosphereProceedings of the Indian Academy of Sciences -Earth and Planetary, Vol. 101, No. 4, December pp. 339-346.IndiaCratton
DS200612-0856
2006
Manglik, A.Manglik, A.Mantle heat flow and thermal structure of the northern block of southern granulite terrain, India.Journal of Geodynamics, Vol. 41, 5, pp. 510-519.Asia, IndiaGeothermometry
DS200612-0857
2005
Manglik, A.Manglik, A., Christensen, U.R.Effect of lithospheric root on decompression melting in plume lithosphere interaction models.Geophysical Journal International, Vol. 164, 1, pp. 259-MantleMelting
DS201312-0373
2012
Mangolin, A.J.Hazen, R.M., Hemley, R.J., Mangolin, A.J.Carbon in Earth's Interior: storage, cycling and life.EOS Transaction of AGU, Vol. 93, 2, Jan 10, 3p.MantleReservoir - diamond mentioned
DS201912-2766
2019
Mangone, A.Agrosi, G., Tempesta, G., Mele, D., Caggiani, MC., Mangone, A., Della Ventura, G., Cestelli-Guidi, M., Allegretta, I., Hutchison, M.T., Nimis, P., Nestola, F.Multiphase inclusions associate with residual carbonate in a transition zone diamond from Juina, Brazil.Lithos, in press available, 31p. pdfSouth America, Brazildeposit - Juina

Abstract: Super-deep diamonds and their mineral inclusions preserve very precious information about Earth’s deep mantle. In this study, we examined multiphase inclusions entrapped within a diamond from the Rio Vinte e um de Abril, São Luiz area (Juina, Brazil), using a combination of non-destructive methods. Micro-Computed X-ray Tomography (?-CXRT) was used to investigate the size, shape, distribution and X-Ray absorption of inclusions and mapping by micro X-ray Fluorescence (?-XRF), ?-Raman Spectroscopy and micro-Fourier Transform Infrared Spectroscopy (?-FTIR) were used to determine the chemical and mineralogical composition of the inclusions. Four large inclusions enclosed in the N-rich diamond core consist of dominant ferropericlase-magnesiowüstite and locally exsolved magnesioferrite. FTIR maps, obtained integrating the band at 1430 cm?1, show also the presence of carbonates. A fifth large inclusion (ca 100 ?m) was remarkable because it showed a very unusual flask shape, resembling a fluid/melt inclusion. Based on ?CXRT tomography and ?-Raman mapping, the flask-shaped inclusion is polyphase and consists of magnetite and hematite partly replacing a magnesiowüstite core and small-volume of gas/vacuum. ?-Raman spectra on the same inclusion revealed local features that are ascribed to post-spinel polymorphs, such as maohokite or xieite, which are stable at P ? 18 GPa, and to huntite, a carbonate with formula CaMg3(CO3)4. This represents the first finding of maohokite and huntite in diamond. We interpret the composition of the inclusions as evidence of formation of ferropericlase-magnesiowüstite and diamond in a carbonate-rich environment at depths corresponding at least to the Transition Zone, followed by oxidation of ferropericlase-magnesiowüstite by reaction with relatively large-volume entrapped melt during diamond ascent.
DS200512-1240
2005
Manheim, F.T.Zhang, C., Manheim, F.T., Hinde, J., Grossman, J.N.Statistical characteristics of a large geochemical database and effect of sample size.Applied Geochemistry, Vol.20, 10, Oct. pp. 1857-1874.TechnologyGeochemistry - not specific to diamonds
DS2001-0019
2001
Manhes, G.Allegre, C., Manhes, G., Lewin, E.Chemical composition of the Earth and the volatility control on planetary genesis.Earth and Planetary Science Letters, Vol. 185, No. 1-2, Feb.15, pp.49-69.GlobalGeochemistry
DS200812-0020
2008
Manhes, G.Allegre, C.J., Manhes, G., Gopel, C.The major differentiation of the Earth at - 4.45 Ga.Earth and Planetary Science Letters, Vol. 267, 1-2, pp.386-398.MantlePetrology
DS1998-0933
1998
Manhica, A.Manhica, A., Grantham, G.H., Guise, P.D.An 40Ar 39Ar study of Zimbabwe Craton Mozambique Belt boundary inManica-Chimoio area, western Mozambique.Journal of African Earth Sciences, Vol. 27, 1A, p. 135. AbstractGlobalGeochronology
DS201012-0248
2010
Manhica, A.D.S.T.Grantham, G.H., Manhica, A.D.S.T., Armstrong, R.A., Kruger, F.J., Loubser, M.New SHRIMP, Rb/Sr and Sm/Nd isotope and whole rock chemical dat a from central Mozambique and western Dronning Maud Land: implications for eastern KalahariJournal of African Earth Sciences, Vol. 59, 1, pp.74-100.Africa, Mozambique, AntarcticaCraton, amalgamation of Gondwana
DS2001-0726
2001
Manhica, A.S.T.D.Manhica, A.S.T.D., Grantham, Armstrong, Guise, KrugerPolyphase deformation and metamorphism at the Kalahari Craton - Mozambique Belt boundary.Geological Society of London, Special Publication, Special Paper 184, pp. 303-22.South Africa, MozambiqueMetamorphism, Craton
DS201901-0037
2018
Manhica, V.Grantham, G., Eglinton, B., Macey, P.H., Ingram,B., Radeneyer, M., Kaiden, H., Manhica, V.The chemistry of Karoo age andesitic lavas along the northern Mozambique coast, southern Africa and possible implications for Gondwana breakup.South African Journal of Geology, Vol. 121, pp. 271-286.Africa, Mozambiquegeodynamics

Abstract: Major, trace, radiogenic isotope and stable isotope data from lavas along the northeastern coast of Mozambique are described. The whole rock composition data demonstrate that the rocks are dominantly andesitic with compositions typical of calc-alkaline volcanic rocks from arc environments. SHRIMP U/Pb data from zircons indicate that the zircons are xenocrystic, having ages of between 500 Ma and 660 Ma, with the age of the lava constrained by Rb/Sr data at ~184 Ma. Strontium, Nd and Pb radiogenic isotope data support an interpretation of extensive mixing between a Karoo age basaltic magma (dolerite) from Antarctica and continental crust similar in composition to the Mozambique basement. Oxygen isotope data also imply a significant crustal contribution to the lavas. Possible tectonic settings for the lavas are at the margin of a plume or from a locally restricted compressional setting during Gondwana breakup processes.
DS1989-0882
1989
Maniar, P.Lidiak, E.G., Maniar, P.A model for the tectonic evolution of the southern midcontinent in early middle Proterozoic timeGeological Society of America Abstract Volume, Vol. 21, No. 1, p. 33. (Abstract only)Missouri, Kansas, Oklahoma, MidcontinentTectonics
DS1989-0928
1989
Maniar, P.D.Maniar, P.D., Piccoli, P.M.Tectonic discrimination of granitoidsGeological Society of America (GSA) Bulletin, Vol. 101, No. 5, May pp. 635-643GlobalGranite, Tectonics
DS1991-0971
1991
Manier, E.Ledru, P., Lasserre, J-L., Manier, E., Mercier, D.The lower Proterozoic of northern Guiana: a revision of the lithology, transcurrent tectonics and sedimentary basin dynamicsBulletin Societe Geologique France, Vol. 162, No. 4, pp. 627-636GlobalBasin, Tectonics
DS1999-0154
1999
ManighettiCourtillot, V., Jaupart, C., Manighetti, TapponnierOn causal links between flood basalts and continental breakupEarth and Planetary Science Letters, Vol. 166, No. 3-4, Mar. pp. 177-196.GlobalBasalts, Tectonics
DS200512-0681
2005
Manikyamba, C.Manikyamba, C., Naqvi, S.M., Subba Rao, D.V., Ram Mohan, M., Khanna, T.C., Rao, T.G., Reddy, G.L.Boninites from the Neoarchean Gadwal greenstone belt, eastern Dharwar Craton, India, implications for Archean subduction processes.Earth and Planetary Science Letters, Vol. 230, 1-2, pp. 65-83.IndiaBoninites
DS200612-0858
2005
Manikyamba, C.Manikyamba, C., Khanna, T.C., Subba Rao, D.V., Charan, S.N., Rao, T.G.Geochemistry and petrogenesis of Gadwai kimberlites, eastern Dharwar Craton India.Geological Society of India, Bangalore November Meeting Group Discussion on Kimberlites and Related Rocks India, Abstract p. 67-68.India, Andhra Pradesh, Dharwar CratonKimberlite - Gadwai
DS201112-0641
2011
Manikyamba, C.Manikyamba, C., Kerrich, R.Geochemistry of alkaline basalts and associated high Mg basalts from the 2.7 Ga Penakacherla Terrane, Dharwar Craton, India: an Archean depleted mantle OIB arrayPrecambrian Research, Vol. 188, pp. 104-122.IndiaAlkaline rocks, basalts
DS201511-1874
2015
Manikyamba, C.Saha, A., Manikyamba, C., Santosh, M., Ganguly, S., Khelen, A.C.Platinum Group Elements ( PGE) geochemistry of komatiites and boninites from Dharwar Craton, India: implications for mantle melting processes.Journal of Asian Earth Sciences, Vol. 105, pp. 300-319.IndiaBoninites

Abstract: High MgO volcanic rocks having elevated concentrations of Ni and Cr are potential hosts for platinum group elements (PGE) owing to their primitive mantle origin and eruption at high temperatures. Though their higher PGE abundance is economically significant in mineral exploration studies, their lower concentrations are also valuable geochemical tools to evaluate petrogenetic processes. In this paper an attempt has been made to evaluate the PGE geochemistry of high MgO volcanic rocks from two greenstone belts of western and eastern Dharwar Craton and to discuss different mantle processes operative at diverse geodynamic settings during the Neoarchean time. The Bababudan greenstone belt of western and Gadwal greenstone belt of eastern Dharwar Cratons are dominantly composed of high MgO volcanic rocks which, based on distinct geochemical characteristics, have been identified as komatiites and boninites respectively. The Bababudan komatiites are essentially composed of olivine and clinopyroxene with rare plagioclase tending towards komatiitic basalts. The Gadwal boninites contain clinopyroxene, recrystallized hornblende with minor orthopyroxene, plagioclase and sulphide minerals. The Bababudan komatiites are Al-undepleted type (Al2O3/TiO2 = 23-59) with distinctly high MgO (27.4-35.8 wt.%), Ni (509-1066 ppm) and Cr (136-3036 ppm) contents. These rocks have low ?PGE (9-42 ppb) contents with 0.2-2.4 ppb Iridium (Ir), 0.2-1.4 ppb Osmium (Os) and 0.4-4.4 ppb Ruthenium (Ru) among Iridium group PGE (IPGE); and 1.4-16.2 ppb Platinum (Pt), 2.8-19 ppb Palladium (Pd) and 0.2-9.8 ppb Rhodium (Rh) among Platinum group PGE (PPGE). The Gadwal boninites are high-Ca boninites with CaO/Al2O3 ratios varying between 0.8 and 1.0, with 12-24 wt.% MgO, 821-1168 ppm Ni and 2307-2765 ppm Cr. They show higher concentration of total PGE (82-207 ppb) with Pt concentration ranging from 13 to 19 ppb, Pd between 65 and 180 ppb and Rh in the range of 1.4-3 ppb compared to the Bababudan komatiites. Ir, Os and Ru concentrations range from 0.6 to 2.2 ppb, 0.2 to 0.6 ppb and 1.4 to 2.6 ppb respectively in IPGE. The PGE abundances in Bababudan komatiites were controlled by olivine fractionation whereas that in Gadwal boninites were influenced by fractionation of chromite and sulphides. The Al-undepleted Bababudan komatiites are characterized by low CaO/Al2O3, (Gd/Yb)N, (La/Yb)N, with positive Zr, Hf, Ti anomalies and high Cu/Pd, Pd/Ir ratios at low Pd concentrations suggesting the derivation of parent magma by high degrees (>30%) partial melting of mantle under anhydrous conditions at shallow depth with garnet as a residual phase in the mantle restite. The komatiites are geochemically analogous to Al-undepleted Munro type komatiites and their PGE compositions are consistent with Alexo and Gorgona komatiites. The S-undersaturated character of Bababudan komatiites is attributed to decompression and assimilation of lower crustal materials during magma ascent and emplacement. In contrast, the higher Al2O3/TiO2, lower (Gd/Yb)N, for Gadwal boninites in combination with negative Nb, Zr, Hf, Ti anomalies and lower Cu/Pd at relatively higher Pd/Ir and Pd concentrations reflect high degree melting of refractory mantle wedge under hydrous conditions in an intraoceanic subduction zone setting. Higher Pd/Ir ratios and S-undersaturation of these boninites conform to influx of fluids derived by dehydration of subducted slab resulting into high fluid pressure and metasomatism of mantle wedge.
DS201906-1347
2019
Manikyamba, C.Sing, T.D., Manikyamba, C., Tang, L., Khelen, A.Phanerozoic magmatism in the Proterozoic Cuddapah basin and its connection with the Pangean supercontinent.Geoscience Frontier, doi.org/10.1016/ j.gsf.2019.04.001Indiamagmatism

Abstract: Magmatic pulses in intraplate sedimentary Basins are windows to understand the tectonomagmatic evolution and paleaoposition of the Basin. The present study reports the U-Pb zircon ages of mafic flows from the Cuddapah Basin and link these magmatic events with the Pangean evolution during late Carboniferous-Triassic/Phanerozoic timeframe. Zircon U-Pb geochronology for the basaltic lava flows from Vempalle Formation, Cuddapah Basin suggests two distinct Phanerozoic magmatic events coinciding with the amalgamation and dispersal stages of Pangea at 300 Ma (Late Carboniferous) and 227 Ma (Triassic). Further, these flows are characterized by analogous geochemical and geochronological signatures with Phanerozoic counterparts from Siberian, Panjal Traps, Emeishan and Tarim LIPs possibly suggesting their coeval and cogenetic nature. During the Phanerozoic Eon, the Indian subcontinent including the Cuddapah Basin was juxtaposed with the Pangean LIPs which led to the emplacement of these pulses of magmatism in the Basin coinciding with the assemblage of Pangea and its subsequent breakup between 400 Ma and 200 Ma.
DS202005-0761
2019
Manikyamba, C.Singh, T.D., Manikyamba, C., Subramanyam, K.S.V., Ganguly, S., Khelen, A., Ramakrsihna Reddy, N.Mantle heterogeneity, plume-lithosphere interaction at rift controlled ocean-continent transition zone: evidence from trace PGE geochemistry of Vempalle flows, Cuddapah basin India.Geoscience Frontiers, in press, 20p. PdfIndiaREE

Abstract: This study reports major, trace, rare earth and platinum group element compositions of lava flows from the Vempalle Formation of Cuddapah Basin through an integrated petrological and geochemical approach to address mantle conditions, magma generation processes and tectonic regimes involved in their formation. Six flows have been identified on the basis of morphological features and systematic three-tier arrangement of vesicular-entablature-colonnade zones. Petrographically, the studied flows are porphyritic basalts with plagioclase and clinopyroxene representing dominant phenocrystal phases. Major and trace element characteristics reflect moderate magmatic differentiation and fractional crystallization of tholeiitic magmas. Chondrite-normalized REE patterns corroborate pronounced LREE/HREE fractionation with LREE enrichment over MREE and HREE. Primitive mantle normalized trace element abundances are marked by LILE-LREE enrichment with relative HFSE depletion collectively conforming to intraplate magmatism with contributions from sub-continental lithospheric mantle (SCLM) and extensive melt-crust interaction. PGE compositions of Vempalle lavas attest to early sulphur-saturated nature of magmas with pronounced sulphide fractionation, while PPGE enrichment over IPGE and higher Pd/Ir ratios accord to the role of a metasomatized lithospheric mantle in the genesis of the lava flows. HFSE-REE-PGE systematics invoke heterogeneous mantle sources comprising depleted asthenospheric MORB type components combined with plume type melts. HFSE-REE variations account for polybaric melting at variable depths ranging from garnet to spinel lherzolite compositional domains of mantle. Intraplate tectonic setting for the Vempalle flows with P-MORB affinity is further substantiated by (i) their origin from a rising mantle plume trapping depleted asthenospheric MORB mantle during ascent, (ii) interaction between plume-derived melts and SCLM, (iii) their rift-controlled intrabasinal emplacement through Archean-Proterozoic cratonic blocks in a subduction-unrelated ocean-continent transition zone (OCTZ). The present study is significant in light of the evolution of Cuddapah basin in the global tectonic framework in terms of its association with Antarctica, plume incubation, lithospheric melting and thinning, asthenospheric infiltration collectively affecting the rifted margin of eastern Dharwar Craton and serving as precursors to supercontinent disintegration.
DS1998-0934
1998
Manion, M.Manion, M.Trends in mining project financeThe Canadian Institute of Mining, Metallurgy and Petroleum (CIM)/MIGA Conference Montreal May, 28p. slide overviews no textGlobalEconomics, discoveries, reserves, Risks, financial schedule, political, mining
DS1989-0929
1989
Manitoba Energy and MinesManitoba Energy and MinesMineral exploration in ManitobaManitoba Energy and Mines, March 12p. Database # 17705ManitobaEconomics, Exploration -overview
DS1989-0930
1989
Manitoba Energy and MinesManitoba Energy and MinesExploration highlightsManitoba Energy and Mines, March 1988-Feb. 1989, 15p. Database # 17704ManitobaExploration, Overview
DS1990-0980
1990
Manitoba Energy and MinesManitoba Energy and MinesMineral exploration in Manitoba 1989; Manitoba exploration highlights March1989-February 1990; List of companies active in ManitobaManitoba Energy and Mines, approx. 25pManitobaExploration overview, Current activities
DS2001-0727
2001
Manitoba Geological SurveyManitoba Geological SurveyOperation Superior: kimberlite indicator mineral survey results 2002 for the northern half of the Knee Lake Greenstone belt. 53M1,2,3,4 53 L 15Manitoba Geological Survey, [email protected], OF 2001-5, 57p. 1 mylar $ 15.ManitobaGeochemistry - database
DS200412-1216
2003
Manitoba Geological SurveyManitoba Geological SurveyThe search for diamonds in Manitoba: an update.Manitoba Geological Survey, pp. 239-246.Canada, ManitobaExploration - overview
DS200412-1217
2004
Manitoba Geological SurveyManitoba Geological SurveyManitoba's integrated anomaly map.Manitoba Geological Survey, Canada, ManitobaGIS map
DS200412-1218
2003
Manitoba Geological SurveyManitoba Geological SurveyThe search for diamonds in Manitoba: an update.Manitoba Geological Survey, Report of activities GS-31, pp. 239-246.Canada, ManitobaOverview exploration
DS200412-1219
2004
Maniyamba, C.Maniyamba, C., Kerrich, R., Naqvi, S.M., Ram Mohan, M.Geochemical systematics of tholeitic basalts from the 2.7 Ga Ramagiri Hungund composite greemstone belt, Dharwar Craton.Precambrian Research, Vol. 134, no. 1-2, Sept. 20, pp. 21-39.IndiaGeochronology - not specific to diamonds
DS201809-2032
2018
Mankelow, J.M.Gunn, A.G., Dorbor, J.K., Mankelow, J.M., Lusty, P.A.J., Deady, E.A., Shaw, R.A.A review of the mineral potential of Liberia.Ore Geology Reviews, Vol. 101, pp. 413-431.Africa, Liberiadiamonds

Abstract: The Republic of Liberia in West Africa is underlain mostly by Precambrian rocks of Archaean (Liberian) age in the west and of Proterozoic (Eburnean) age in the east. By analogy with similar terranes elsewhere in the world, and in West Africa in particular, the geology of Liberia is favourable for the occurrence of deposits of a wide range of metals and industrial minerals, including gold, iron ore, diamonds, base metals, bauxite, manganese, fluorspar, kyanite and phosphate. Known gold deposits, mostly orogenic in style, occur widely and are commonly associated with north-east-trending regional shear zones. Gold mining commenced at the New Liberty deposit in western Liberia in 2015, while significant gold resources have also been identified at several other sites in both Archaean and Proterozoic terranes. Liberia has large resources of itabirite-type iron ores, most of which are located in the Liberian terrane, and was the largest producer in Africa prior to the onset of civil war in 1989. Production of iron ore is currently restricted to a single mine, Yekepa, in the Nimba Range. Other important deposits, some of them previously mined, include Bong, the Western Cluster, Putu and Goe Fantro. There is a long history of alluvial diamond production in western and central Liberia, together with more than 160 known occurrences of kimberlite. Most of the known kimberlites occur in three clusters of small pipes and abundant dykes, located at Kumgbor, Mano Godua and Weasua, close to the border with Sierra Leone. Many of these are considered to be part of a single province that includes Jurassic age diamondiferous kimberlites in Sierra Leone and Guinea. Deposits and occurrences of a wide range of other metals and industrial minerals are also known. Several of these have been worked on a small scale in the past, mainly by artisanal miners, but most are poorly known in detail with sub-surface information available at only a few localities. By comparison with most other countries in West Africa, the geology of Liberia is poorly known and there has been very little systematic exploration carried out for most commodities other than gold, iron ore and diamonds since the 1960s and 1970s. Further detailed field and laboratory investigations using modern techniques are required to properly evaluate the potential for the occurrence of economic deposits of many minerals and metals in a variety of geological settings. Digital geological, geochemical, geophysical and mineral occurrence datasets, including new national airborne geophysical survey data, provide a sound basis for the identification of new exploration targets, but in almost every part of the country there is a need for new and more detailed geological surveys to underpin mineral exploration.
DS1990-1387
1990
Mankenda, A.Sobolev, N.V., Mankenda, A., Kaminsky, F.V., Sobolev, V.N.Garnets from kimberlites of north-east Angola and relation of Their composition with diamond content.(Russian)Doklady Academy of Sciences Akademy Nauk SSSR, (Russian), Vol. 315, No. 5, pp. 1225-1229AngolaGarnets and diamonds, Mineralogy
DS1992-0858
1992
Mankenda, A.Kharkiv, A.D., Levin, V.I., Mankenda, A., Safronov, A.F.The Camafuca-Camazambo kimberlite pipe of Angola, the largest in theworldInternational Geology Review, Vol. 34, No. 7, July pp. 710-719AngolaKimberlite, Deposit -Camafuca-Camazambo
DS1992-1448
1992
Mankenda, S.A.Sobolev, N.V., Mankenda, S.A., Kaminsky, F.V., Sobolev, V.N.Garnets from kimberlites of northeastern Angola and correlations between their compositions and diamond content.Doklady Academy of Sciences USSR, Earth Science Section, Vol. 315, pp. 238-242.AngolaGarnet mineralogy, Diamond content
DS1988-0437
1988
Mankin, C.J.Mankin, C.J.Geologic mapping: will needs be met?Geotimes, Vol. 33, No. 11, November pp. 6-7GlobalMapping
DS1989-0830
1989
Manley, C.R.Krinsley, D.H., Manley, C.R.back scattered electron microscopy as an advanced technique in petrographyJournal of Geology Education, Vol. 37, No. 3, May pp. 202-210GlobalPetrography, Overview
DS2000-0612
2000
Manley, C.R.Manley, C.R., Glazner, A.F., Farmer, G.L.Timing of volcanism in the Sierra Nevada of California: evidence for Pliocene delamination of batholithic rootGeology, Vol. 28, No. 9, Sept. pp. 811-14.CaliforniaTectonics, Magmatism - alkaline
DS1988-0253
1988
Manley, G.Gershon, M., Allen, L.E., Manley, G.Application of a new approach for drillholes location optimizationInternational Journal of Surface Mining, Vol. 2, pp. 27-31. Database # 17471GlobalDrilling, Geostatistics
DS1996-0877
1996
Manley, W.F.Manley, W.F.Late glacial flow patterns, deglaciation, and Post glacial emergence of South central Baffin Island...Canadian Journal of Earth Sciences, Vol. 33 No. 11, Nov. pp. 1499-1510.GlobalGeomorphology, Glaciation
DS1995-1155
1995
Mann, A.Mann, A.Metallic and industrial mineral assessment report for the Pearson Marguerite Audet exploration permits.Alberta Geological Survey, MIN 19950014AlbertaExploration - assessment
DS201610-1840
2016
Mann, A.Aravanis, T., Chen, J., Fuechsle, M., Grujic, M., Johnston, P., Kok, Y., Magaraggia, R., Mann, A., Mann, L., McIntoshm S., Rheinberger, G., Saxey, D., Smalley, M., van Kann, F., Walker, G., Winterflood, J.VK1 tm - a next generation airborne gravity gradiometer.ASEG-PESA-AIG 2016 25th Geophysical Conference, Abstract 5p.TechnologyGradiometer

Abstract: The minerals exploration industry’s demand for a highly precise airborne gravity gradiometer has driven development of the VK1TM Airborne Gravity Gradiometer, a collaborative effort by Rio Tinto and the University of Western Australia. VK1TM aims to provide gravity gradient data with lower uncertainty and higher spatial resolution than current commercial systems. In the recent years of VK1TM development, there have been significant improvements in hardware, signal processing and data processing which have combined to result in a complete AGG system that is approaching competitive survey-ready status. This paper focuses on recent improvements. Milestone-achieving data from recent lab-based and moving-platform trials will be presented and discussed, along with details of some advanced data processing techniques that are required to make the most use of the data.
DS1995-1156
1995
Mann, A.G.Mann, A.G.Metallic and industrial mineral assessment report for the Fort Smith and Fitzgerald exploration project.Alberta Geological Survey, MIN 19950011AlbertaExploration - assessment
DS1996-0878
1996
Mann, A.G.Mann, A.G., GRQ Mining Inc.Geological report on Dog river industrial mineral permit 9392060004 Fort Smith 74 M 14Alberta Geological Survey, MIN 19960020AlbertaExploration - assessment
DS1993-0968
1993
Mann, A.W.Mann, A.W., et al.The new mobile metal ion approach to the detection of buriedmineralizationAustralian Geological Survey, pp. 223-228GlobalTechniques, Laterization
DS1992-0742
1992
Mann, C.J.Hunter, R.L., Mann, C.J.Techniques of determining probabilities of geologic events and processesOxford University Press, 304pGlobalComputer probabilities, Book -ad
DS1994-0874
1994
Mann, C.J.Kanagy, S.P. II, Mann, C.J.Electrical properties of eolian sand and siltEarth Science Reviews, Vol. 36, pp. 181-204GlobalGeophysics, Experimental - sedimentology
DS1994-0875
1994
Mann, C.J.Kanagy, S.P. II, Mann, C.J.Electrical properties of eolian sand and siltEarth Science Reviews, Vol. 36, pp. 181-204.GlobalGeophysics, Experimental - sedimentology
DS201610-1840
2016
Mann, L.Aravanis, T., Chen, J., Fuechsle, M., Grujic, M., Johnston, P., Kok, Y., Magaraggia, R., Mann, A., Mann, L., McIntoshm S., Rheinberger, G., Saxey, D., Smalley, M., van Kann, F., Walker, G., Winterflood, J.VK1 tm - a next generation airborne gravity gradiometer.ASEG-PESA-AIG 2016 25th Geophysical Conference, Abstract 5p.TechnologyGradiometer

Abstract: The minerals exploration industry’s demand for a highly precise airborne gravity gradiometer has driven development of the VK1TM Airborne Gravity Gradiometer, a collaborative effort by Rio Tinto and the University of Western Australia. VK1TM aims to provide gravity gradient data with lower uncertainty and higher spatial resolution than current commercial systems. In the recent years of VK1TM development, there have been significant improvements in hardware, signal processing and data processing which have combined to result in a complete AGG system that is approaching competitive survey-ready status. This paper focuses on recent improvements. Milestone-achieving data from recent lab-based and moving-platform trials will be presented and discussed, along with details of some advanced data processing techniques that are required to make the most use of the data.
DS1994-1826
1994
Mann, P.Van der Hilst, R., Mann, P.Tectonic implications of tomographic images of subducted lithosphere beneath northwestern South AmericaGeology, Vol. 22, No. 5, May pp. 451-454Venezuela, Colombia, South America, ChileTectonics, Slab subduction
DS1997-0428
1997
Mann, P.Gordon, M.B., Mann, P., Flores, R.Cenozoic tectonic history of the North America - Caribbean plate boundary zone in western CubaJournal of Geophysical Research, Vol. 102, No. 5, May 10, pp. 10, 055-82GlobalTectonics, Plate boundary
DS1997-0725
1997
Mann, P.Mann, P.Model for the formation of large transtensional basins in zones of tectonicescapeGeology, Vol. 25, No. 3, March, pp. 211-214Europe, Aegean SeaBasins, Tectonics
DS1999-0441
1999
Mann, P.Mann, P.Subduction to strike slip transitions on plate boundaries... Penrose Conference report.Gsa Today, Vol.9, No. 7, July pp. 14-16.MantleSubduction, Plate boundary
DS1995-0234
1995
Mann, R.Bundtzen, T.K., Fonseca, A.L., Mann, R.Geology and mineral deposits of the Russian Far EastGlacier House Publications, 160p. $ 40.00RussiaBook -table of contents, Mneral deposits of Far East
DS1860-0234
1874
Mann, R.J.Mann, R.J.Additional Remarks on the Commercial Aspects and Influence Of the South African Diamond and Gold Fields.Soc. Arts (London) Journal, Vol. 22, PP. 392-397.Africa, South Africa, Cape Province, Griqualand WestEconomics
DS1860-0239
1874
Mann, R.J.Shepstone, T., Mann, R.J.Remarks on the Geographical and Physical Character of the Diamond Fields of South Africa.Soc. Arts Journal of (London), Vol. 22, PP. 390-392.Africa, South Africa, Cape ProvinceGeology
DS1989-1229
1989
Mann, U.Poelchau, H.S., Mann, U.Evolution of sedimentary basins- the integrated modeling approach. AnintroductionGeologische Rundschau, Vol. 78, No. 1, pp. 1-6. Database # 18160GlobalBasins, Modeling
DS200812-0370
2008
Mann, U.Frost, D.J., Mann, U., Asahara, Y., Rubie, D.C.The redox state of the mantle during and just after core formation.Philosophical Transactions Royal Society of London Series A Mathematical Physical and Engineering Sciences, Vol. 366, no. 1883, pp. 4315-4338.MantleRedox
DS201112-0885
2011
Mann, U.Rubie, D.C., Frost, D.J., Mann, U., Asahara, Y., Nimmo, F., Tsuno, K., Kegler, P., Holzheid, A., Palme, H.Heterogeneous accretion, composition and core-mantle differentiation of the Earth.Earth and Planetary Science Letters, Vol. 301, 1-2, pp. 31-42.MantleAccretion
DS1996-0879
1996
Mann. A.G.Mann. A.G.Assessment report - Albeta Mineral exploration permit 939310004 and 5 Holyoke,Beartrap Lake, eastern Alberta.Alberta Geological Survey, MIN 19960003Alberta, EasternExploration - assessment, Albury Resources Ltd.
DS1960-0273
1962
Mannard, G.Mannard, G.Geology of the Singida Kimberlite PipesMontreal: Ph.d. Thesis, University Mcgill, Tanzania, East AfricaGeology, Kimberlite, Mineralogy, Petrology
DS1960-0984
1968
Mannard, G.W.Mannard, G.W.The Surface Expression of Kimberlite PipesGeological Association of Canada (GAC) Proceedings, Vol. 19, PP. 15-21.United States, Great Lakes, CanadaKimberlite, Genesis, Geology, Geomorphology
DS201112-0373
2011
manning, A.H.Gleeson, T., Smith, L., Moosdorf, N., Hartmann, J., Durr, H.H., manning, A.H., Van Beek, P.H., Jellinek, A.Mapping permeability over the surface of the Earth.Geophysical Research Letters, Vol. 38, L02401MantleGeophysics
DS200612-0570
2006
Manning, C.Hermann, J., Manning, C.Deep fluid release from the slab.Goldschmidt Conference 16th. Annual, S6-02 theme abstract 1/8p. goldschmidt2006.orgMantleMelting
DS201312-0572
2013
Manning, C.Manning, C., Li, Y., Eguchi, J.Fluids, subduction, and deep carbon.Goldschmidt 2013, AbstractMantleCarbon cycle
DS201703-0400
2017
Manning, C.Edmonds, M., Manning, C.Synthesizing our understanding of Earth's deep carbon. Udachnaya pipe used as an example.EOS Transaction of AGU, https://doi.org/10.1029/2017EO67913RussiaCarbon
DS1993-0969
1993
Manning, C.E.Manning, C.E., Ingebritsen, S.E., Bird, D.K.Missing mineral zones in contact metamorphosed basaltsAmerican Journal of Science, Vol. 293, No. 9, November pp. 894-938GlobalBasalt
DS1994-1097
1994
Manning, C.E.Manning, C.E.Fractal clustering of metamorphic veinsGeology, Vol. 22, No. 4, April pp. 335-338Globalmetamorphism, Fluid flow
DS1996-0880
1996
Manning, C.E.Manning, C.E.Coupled reaction and flow in subduction zones: silica metasomatism in The mantle wedge.In: Jamtveit -Fluid flow and transport in rocks, pp. 139-148.MantleMetasomatism
DS2002-1133
2002
Manning, C.E.Newton, R.C., Manning, C.E.Experimental determination of calcite solubility in H2O NaCl solutions at deep crust/upper mantle pressures and temperatures: implications for metasomatic processesAmerican Mineralogist, Vol. 87, pp. 1401-9.India, southernAlkaline magmatism - shear zones
DS2002-1616
2002
manning, C.E.Tropper, P., manning, C.E., Essene, E.J.The substitution of Al and F in titanite at high pressure and temperature experimental constraints on phase relations and solid solution properties.Journal of Petrology, Vol. 43, No. 10, Oct.pp. 1787-1814.GlobalUltra high pressure, UHP
DS200412-1220
2004
Manning, C.E.Manning, C.E.The chemistry of subduction zone fluids.Earth and Planetary Science Letters, Vol. 223, 1-2, June, 30, pp. 1-16.MantleMantle wedge, metasomatism, water
DS200512-1101
2005
Manning, C.E.Tropper, P., Manning, C.E.Very low solubility of rutile in H2O at high pressure and temperature, and its implications for Ti mobility in subduction zones.American Mineralogist, Vol. 90, pp. 502-505.Geothermometry
DS200612-0859
2006
Manning, C.E.Manning, C.E.What's so super about supercritical fluids in subduction zones?Geochimica et Cosmochimica Acta, Vol. 70, 18, p. 10, abstract only.MantleSubduction - geochemistry
DS200712-1205
2007
Manning, C.E.Yin, A., Manning, C.E., Lovera, O., Menold, C.A., Chen, X., Gehrels, G.Early Paleozoic tectonic and thermomechanical evolution of ultrahigh pressure (UHP) metamorphic rocks in the northern Tibetan Plateau, northwest China.International Geology Review, Vol. 49, 8, pp. 681-716.ChinaUHP
DS200912-0841
2009
Manning, C.E.Young, E.D., Tonui, E., Manning, C.E., Schauble, E., Macris, C.A.Spinel olivine magnesium isotope thermometry in the mantle and implications for the MG isotopic composition of Earth.Earth and Planetary Science Letters, Vol. 288, 3-4, pp. 524-533.MantleGeothermometry
DS201012-0307
2010
Manning, C.E.Ingebritsen, S.E., Manning, C.E.Permeability of the continental crust: dynamic variations inferred from seismicity and metamorphism.Geofluids, Vol. 10, 1-2, pp. 193-205.MantleChemistry
DS201012-0881
2009
Manning, C.E.Young, E.D., Tonui, E., Manning, C.E., Schauble, E., Macris, C.A.Spinel olivine magnesium isotope thermometry in the mantle and implications for the Mg isotopic composition of Earth.Earth and Planetary Science Letters, Vol. 288, pp. 524-533..MantleGeochemistry
DS201112-0448
2010
Manning, C.E.Hopkins, M.D., Harrison, T.M., Manning, C.E.Constraints on Hadean geodynamics from mineral inclusions in > 4 Ga zircons.Earth and Planetary Science Letters, Vol. 298, 3-4, pp. 367-376.MantleGeochronology
DS201807-1511
2018
Manning, C.E.Manning, C.E.Fluids of the lower crust: deep is different.Annual Review of Earth and Planetary Sciences, Vol. 46, pp. 67-97.Mantlecore, boundary

Abstract: Deep fluids are important for the evolution and properties of the lower continental and arc crust in tectonically active settings. They comprise four components: H2O, nonpolar gases, salts, and rock-derived solutes. Contrasting behavior of H2O-gas and H2O-salt mixtures yields immiscibility and potential separation of phases with different chemical properties. Equilibrium thermodynamic modeling of fluid-rock interaction using simple ionic species known from shallow-crustal systems yields solutions too dilute to be consistent with experiments and resistivity surveys, especially if CO2 is added. Therefore, additional species must be present, and H2O-salt solutions likely explain much of the evidence for fluid action in high-pressure settings. At low salinity, H2O-rich fluids are powerful solvents for aluminosilicate rock components that are dissolved as polymerized clusters. Addition of salts changes solubility patterns, but aluminosilicate contents may remain high. Fluids with Xsalt = 0.05 to 0.4 in equilibrium with model crustal rocks have bulk conductivities of 10?1.5 to 100 S/m at porosity of 0.001. Such fluids are consistent with observed conductivity anomalies and are capable of the mass transfer seen in metamorphic rocks exhumed from the lower crust.
DS201812-2888
2018
Manning, C.E.Stagno, V., Stopponi, V., Kono, Y., Manning, C.E., Irifune, T.Experimenal determination of the viscosity of Na2CO3 melt between 1.7 and 4.6 Gpa at 1200-1700 C: implications for the rheology of carbonatite magmas in the Earth's upper mantle.Chemical Geology, Vol. 501, pp. 19-25.Mantlecarbonatite

Abstract: Knowledge of the rheology of molten materials at high pressure and temperature is required to understand magma mobility and ascent rate at conditions of the Earth's interior. We determined the viscosity of nominally anhydrous sodium carbonate (Na2CO3), an analogue and ubiquitous component of natural carbonatitic magmas, by the in situ “falling sphere” technique at 1.7, 2.4 and 4.6?GPa, at 1200 to 1700?°C, using the Paris-Edinburgh press. We find that the viscosity of liquid Na2CO3 is between 0.0028?±?0.0001?Pa•s and 0.0073?±?0.0001?Pa•s in the investigated pressure-temperature range. Combination of our results with those from recent experimental studies indicate a negligible dependence on pressure from 1?atm to 4.6?GPa, and a small compositional dependence between molten alkali metal-bearing and alkaline earth metal-bearing carbonates. Based on our results, the viscosity of Na2CO3 is consistent with available viscosity data of both molten calcite (determined at high pressure and temperature) and Na2CO3 at ambient pressure. Molten Na2CO3 is a valid experimental analogue for study of the rheology of natural and/or synthetic near-solidus carbonatitic melts. Estimated values of the mobility and ascent velocity of carbonatitic melts at upper conditions are between 70 and 300?g?cm?3•Pa?1•s?1 and 330-1450?m•year?1, respectively, when using recently proposed densities for carbonatitic melts. The relatively slow migration rate allows magma-rock interaction over time causing seismic anomalies and chemical redox exchange.
DS201912-2815
2019
Manning, C.E.Plank, T., Manning, C.E.Subducting carbon.Nature, Vol. 574, pp. 343-352.Mantlecarbon

Abstract: A hidden carbon cycle exists inside Earth. Every year, megatons of carbon disappear into subduction zones, affecting atmospheric carbon dioxide and oxygen over Earth’s history. Here we discuss the processes that move carbon towards subduction zones and transform it into fluids, magmas, volcanic gases and diamonds. The carbon dioxide emitted from arc volcanoes is largely recycled from subducted microfossils, organic remains and carbonate precipitates. The type of carbon input and the efficiency with which carbon is remobilized in the subduction zone vary greatly around the globe, with every convergent margin providing a natural laboratory for tracing subducting carbon.
DS202004-0534
2020
Manning, C.E.Stagno, V., Stopponi, V., Kono, Y., D'Arco, A., Lupi, S., Romano, C., Poe, B.T., Foustoukos, D.J., Scarlato, P., Manning, C.E.The viscosity and atomic structure of volatile bearing melililititic melts at high pressure and temperature and the transport of deep carbon.Minerals MDPI, Vol. 10, 267 doi: 10.23390/min10030267 14p. PdfMantleMelililite, carbon

Abstract: Understanding the viscosity of mantle-derived magmas is needed to model their migration mechanisms and ascent rate from the source rock to the surface. High pressure-temperature experimental data are now available on the viscosity of synthetic melts, pure carbonatitic to carbonate-silicate compositions, anhydrous basalts, dacites and rhyolites. However, the viscosity of volatile-bearing melilititic melts, among the most plausible carriers of deep carbon, has not been investigated. In this study, we experimentally determined the viscosity of synthetic liquids with ~31 and ~39 wt% SiO2, 1.60 and 1.42 wt% CO2 and 5.7 and 1 wt% H2O, respectively, at pressures from 1 to 4.7 GPa and temperatures between 1265 and 1755 °C, using the falling-sphere technique combined with in situ X-ray radiography. Our results show viscosities between 0.1044 and 2.1221 Pa•s, with a clear dependence on temperature and SiO2 content. The atomic structure of both melt compositions was also determined at high pressure and temperature, using in situ multi-angle energy-dispersive X-ray diffraction supported by ex situ microFTIR and microRaman spectroscopic measurements. Our results yield evidence that the T-T and T-O (T = Si,Al) interatomic distances of ultrabasic melts are higher than those for basaltic melts known from similar recent studies. Based on our experimental data, melilititic melts are expected to migrate at a rate ~from 2 to 57 km•yr?1 in the present-day or the Archaean mantle, respectively.
DS202010-1884
2020
Manning, C.E.Wiedendorfer, D., Manning, C.E., Schmidt, M.W.Carbonate melts in the hydrous upper mantle.Contributions to Mineralogy and Petrology, doi.org/10.1007/ s00410-020-01708 17p. Pdf Mantlecarbonatite

Abstract: Carbonatite compositions resulting from melting of magnesian calcite?+?olivine?+?clinopyroxene were experimentally determined in the system CaO-MgO-SiO2-CO2-H2O as a function of temperature and bulk H2O contents at 1.0 and 1.5 GPa. The melting reaction and melt compositions were found to be highly sensitive to H-loss or -gain during experiments. We hence designed a new hydrogen-trap technique, which provided sufficient control to obtain consistent results. The nominally dry solidus temperatures at 1.0 and 1.5 GPa are 1225-1250 °C and 1275-1300 °C, respectively. At 1.0 GPa, the solidus temperature decreases with H2O increasing to 3.5 wt% (1025-1050 °C), then remains approximately constant at higher H2O concentrations. Our nominally dry solidus temperatures are up to 140 °C higher than in previous studies that did not take measures to limit hydrogen infiltration and hence suffered from H2O formation in the capsule. The near-solidus anhydrous melts have 7-8 wt% SiO2 and molar Ca/(Ca?+?Mg) of 0.78-0.82 (XCa). Melting temperatures decrease by as much as 200 °C with increasing XH2O in the coexisting COH-fluid. Concomitantly, near-solidus melt compositions change with increasing bulk H2O from siliceous Ca-rich carbonate melts to Mg-rich silico-carbonatites with up to 27.8 wt% SiO2 and 0.55 XCa. The continuous compositional array of Ca-Mg-Si carbonatites demonstrates the efficient suppression of liquid immiscibility in the alkali-free system. Diopside crystallization was found to be sensitive to temperature and bulk water contents, limiting metasomatic transformation of carbonated upper mantle to wehrlite at 1.0-1.5 GPa to?
DS202104-0592
2021
Manning, C.E.Manning, C.E., Frezzotti, M.L.Subduction-zone fluids. Deep fluidsElements, Vol. 16, pp. 395-400.Mantlewater

Abstract: Fluids are essential to the physical and chemical processes in subduction zones. Two types of subduction-zone fluids can be distinguished. First, shallow fluids, which are relatively dilute and water rich and that have properties that vary between subduction zones depending on the local thermal regime. Second, deep fluids, which possess higher proportions of dissolved silicate, salts and non-polar gases relative to water content, and have properties that are broadly similar in most subduction systems, regardless of the local thermal structure. We review key physical and chemical properties of fluids in two key subduction-zone contexts-along the slab top and beneath the volcanic front-to illustrate the distinct properties of shallow and deep subduction-zone fluids.
DS202104-0610
2021
Manning, C.E.Steele-MacInnis, M., Manning, C.E.Hydrothermal properties of geologic fluids.Elements, Vol. 16, pp. 375-380.Mantlewater

Abstract: Aqueous fluids are critical agents in the geochemical evolution of Earth’s interior. Fluid circulation and fluid-rock reactions in the Earth take place at temperatures ranging from ambient to magmatic, at pressures from ambient to extreme, and involve fluids that range from nearly pure H2O through to complex, multicomponent solutions. Consequently, the physical and chemical properties of hydrothermal fluids vary widely as functions of geologic setting; this variation strongly impacts fluid-driven processes. This issue will focus on the nature of geologic fluids at hydrothermal conditions and how such fluids affect geologic processes in some major settings.
DS1995-1157
1995
Manning, D.A.C.Manning, D.A.C.Introduction to industrial mineralsChapman and Hall, GlobalBook -ad, Industrial minerals
DS1991-1745
1991
Manning, E.R.Towie, N.J., Marz, M.R., Bush, M.D., Manning, E.R.The Aries Diamondiferous kimberlite pipe: central Kimberley Block, westernAustraliaProceedings of Fifth International Kimberlite Conference held Araxa June 1991, Servico Geologico do Brasil (CPRM) Special, pp. 435-436AustraliaSampling, prospecting, geophysics, Structure, geochemistry, alluvials
DS1994-1793
1994
Manning, E.R.Towie, N.J., Bush, M.D., Manning, E.R., Marx, M.R., Ramsay, R.R.The Aries Diamondiferous kimberlite pipe central Kimberley Block, westernAustralia: exploration, setting and evaluation.Proceedings of Fifth International Kimberlite Conference, Vol. 2, pp. 319-328.AustraliaDiamond exploration, Deposit -Aries
DS1997-0726
1997
Manning, S.Manning, S., Morris, W.High resolution magnetic anomaly maps from ERLIS compilation: an example from Kirkland LakeThe Canadian Mining and Metallurgical Bulletin (CIM Bulletin), Vol. 90, No. 1012, July pp. 89-93OntarioComputer - ERLIS, Geophysics - magnetics Kirkland Lake area
DS1998-0935
1998
Manning Clark CentreManning Clark Centre, ANUMineral systems and the Crust- Upper Mantle of southeast AustraliaManning Clark Centre, ANU, April 20-22 1998AustraliaConference - April 1998, Crust Upper mantle
DS1910-0367
1913
Mannix, J.B.Mannix, J.B.Mines and their StoryLondon: Sedgwick And Jackson Ltd., 337P.South AfricaKimberley, Geology, History
DS1910-0202
1911
Mannucci, U.Mannucci, U.Le Pietre PrezioseMilano: Della Real Casa., 398P.GlobalKimberley, Diamonds
DS200812-0710
2008
Manon, M.R.Manon, M.R., Dachs, E., Essene, E.J.Low T heat capacity measurements and new entropy dat a for titanite ( sphene) implications for thermobarometry of high pressure rocks.Contributions to Mineralogy and Petrology, Vol. 156, 6, pp. 709-720.TechnologyUHP
DS1989-0266
1989
Manoussis, S.Chorowicz, J., Kim, J., Manoussis, S., Rudant, J-P., Foin, P.A new technique for recognition of geological and geomorphological patterns in digital terrain modelsRemote Sensing of the Environment, Vol. 29, pp. 229-239GlobalRemote sensing, Geomorphology
DS1960-1162
1969
Manoyian, Z.Manoyian, Z.The GemstersOpa-locka Fla: Todd-z Corp., 144P.United States, Gulf Coast, Arkansas, PennsylvaniaBlank
DS2002-1512
2002
Manser, K.Smith, D., Moser, D.E., Connelly, J.N., Manser, K., Schulze, D.J.U Pb zircon ages of eclogites, garnetites and Cenozoic rock water reactions in Proterozoic mantle below the Colorado Plateau.Geological Society of America Annual Meeting Oct. 27-30, Abstract p. 253.Colorado, WyomingDaitremes, geochronology
DS2001-0728
2001
Mansfeld, J.Mansfeld, J.Age and neodymium constraints on the Paleoproterozoic tectonic evolution in the Baltic Sea region.Tectonophysics, Vol. 339, No. 1-2, pp. 135-51.Baltic ShieldGeochronology, Tectonics
DS2002-0158
2002
Mansfeld, J.Bingen, B., Mansfeld, J., Sigmond, E.M.O., Stein, H.Baltica - Laurentia link during the Mesoproterozoic: 1.27 Ga development of continental basins in the Sveconorwegian Orogen, southern Norway.Canadian Journal of Earth Science, Vol. 39, 9, Sept.pp. 1425-40.NorwayTectonics, Geochronology
DS2002-0441
2002
Mansfeld, J.Evins, P.M., Mansfeld, J., Laajoki, K.Geology and geochronology of the Suomujarvi Complex: a new Archean gneiss region in the NE Baltic Shield, Finland.Precambrian Research, Vol. 116, No. 3-4, pp. 285-306.FinlandGeneral geology - not specific to diamonds
DS2003-0112
2003
Mansfeld, J.Bingen, B., Nordgulen, O., Sigmond, E.M., Tucker, R., Mansfeld, J., Hogdahl, K.Relations between 1.19 - 1.13 Ga continental magmatism, sedimentation andPrecambrian Research, Vol. 124, 2-4, pp. 215-241.NorwayBlank
DS200412-0155
2003
Mansfeld, J.Bingen, B., Nordgulen, O., Sigmond, E.M., Tucker, R., Mansfeld, J., Hogdahl, K.Relations between 1.19 - 1.13 Ga continental magmatism, sedimentation and metamorphism, Sveconorwegian province, S. Norway.Precambrian Research, Vol. 124, 2-4, pp. 215-241.Europe, NorwayMagmatism
DS200512-1157
2005
Mansfeld, J.Vuorinen, J.H., Halenius, U., Whitehouse, M.J., Mansfeld, J., Skelton, A.D.L.Compositional variations (major and trace elements) of clinopyroxene and Ti and radite from pyroxenite, ijolite and nepheline syenite, Alno Island, Sweden.Lithos, Vol. 81, 1-4, April pp. 55-77.Europe, Sweden, Alno IslandGeochemistry, melteigite
DS200712-0019
2007
Mansfeld, J.Andersson, U.B., Rutanen, HG., Johansson, A., Mansfeld, J., Rimsa, A.Characterization of the Paleoproterozoic mantle beneath the Fennoscandian shield: geochemistry and isotope geology (Nd, Sr) of ~1.8 Ga mafic plutonic rocks ...International Geology Review, Vol. 49, 7, pp. 587-625.Europe, SwedenGeochronology
DS1910-0556
1918
Mansfield, G.C.Mansfield, G.C.History of Butte County, Biographical SketchesHistorical Record Company, Los Angeles, PP. 263; P. 301; PP. 369-370.United States, California, West CoastBlank
DS1996-0881
1996
Mansfield, J.Mansfield, J.Geological, geochemical and geochronological evidence for a new Paleoproterozoic terrane southeastern SwedenPrecambrian Research, Vol. 77, No. 1-2, March 1, pp. 91-104SwedenGeochronology, geochemistry, Proterozoic terrane
DS1980-0223
1980
Mansker, W.Mansker, W., Keil, K., Husler, J.A Petrologic Comparison of Olivine Nephelinites and Olivineme lilite Nephelinites: Implications Regarding Nepheline Evolution.Geological Society of America (GSA), Vol. 12, No. 7, P. 475, (abstract.).United States, HawaiiBlank
DS1970-0752
1973
Mansker, W.L.Mansker, W.L.Petrology of a Southeastern Missouri Ultramafic PipeRolla: Msc. Thesis, University Missouri, Rolla., 53P.Missouri, United States, Central StatesAlnoite, Avon
DS1975-0331
1976
Mansker, W.L.Mansker, W.L., Brookins, D.G., Landis, G.P., et al.Post Devonian Distremes in Southeast Missouri, Investigation of the Avon Kimberlite and Some Emplacement Parameters.Eos, Vol. 57, No. 10, P. 761, (abstract.).GlobalKimberlite, Central States, Alnoite
DS1985-0061
1985
Mansker, W.L.Berendsen, P., Cullers, R.L., Mansker, W.L., Cole, G.P.Late Cretaceous Kimberlite and Lamproite Occurrences in Eastern Kansas, United States (us)Geological Society of America (GSA), Vol. 17, No. 3, FEBRUARY P. 151. (abstract.).United States, Kansas, Central States, WilsonWinkler Crater, Rose Dome, Occurrences
DS1985-0089
1985
Mansker, W.L.Brookins, D.G., Mansker, W.L.Upper Mantle and Crustal Rocks in North Central Kansas: Evidence from Kimberlites.6th. International Conference Basement Tectonics, Held Sant Fe, Septemb, P. 13. (abstract.).United States, Central States, KansasPetrography, Geochemistry, Geophysics
DS1985-0409
1985
Mansker, W.L.Mansker, W.L., Richards, B.D., Cole, G.P.A Review and Comparison of Known and Recently Discovered Kimberlites in the Riley County, Kansas District.Preprint Paper Geological Society of America (gsa) Southeastern Section- Arkans, 22P.United States, Central States, KansasKimberlite Occurrences, Geology, Age, Geophysics, Magnetic
DS1985-0410
1985
Mansker, W.L.Mansker, W.L., Richards, B.D., Cole, G.P.A Review and Comparison of Kansas KimberlitesGeological Society of America (GSA), Vol. 17, No. 3, P. 166. (abstract.).United States, Kansas, Central StatesWinkler, Stockdale, Bala
DS1985-0640
1985
Mansker, W.L.Springfield, J.T., Mansker, W.L.Factors Affecting Garnet Metamerism and Applications in Kimberlite Evaluation/exploration.Geological Society of America (GSA), Vol. 17, No. 3, P. 193. (abstract.).GlobalGarnet, Population, Mineral Chemistry, Colour
DS1986-0112
1986
Mansker, W.L.Brookins, D.G., Mansker, W.L.Upper mantle and crustal rocks in North Central Kansas: evidence fromkimberlitesInternational Basement Tectonics Sixth Conference, p. 196. abstractKansasUSA, Mantle genesis
DS1986-0521
1986
Mansker, W.L.Mansker, W.L.Garnet suites in kimberlites and lamproitesMicrobeam Analysis, Vol. 21st. p. 126GlobalLamproite
DS1987-0434
1987
Mansker, W.L.Mansker, W.L., Richards, B.D., Cole, G.P.A note on newly discovered kimberlites in Riley County, KansasMantle metasomatism and alkaline magmatism, edited E. Mullen Morris and, No. 215, pp. 197-205KansasGeophysics
DS1997-0727
1997
Manson, C.J.Manson, C.J.The costs and values of geoscience informationGis Proc, Vol. 28, 120p. app. $ 50.00GlobalBook - table of contents, Information technology, databases, electronic, email
DS1975-0165
1975
Manson, D.V.Prinz, M., Manson, D.V., Hlava, P.F., Keil, K.Inclusions in Diamonds: Garnet Lherzolite and Eclogite Assemblages.Physics and Chemistry of the Earth., Vol. 9, PP. 797-815.South AfricaMineral Chemistry
DS1984-0476
1984
Manson, D.V.Manson, D.V., Stockton, C.M.Pyrope Spessartine Garnets With Unusual Color BehaviorGems And Gemology, Vol. 20, WINTER PP. 200-207.GlobalGarnet, Mineralogy
DS2001-0729
2001
Manson, M.Manson, M.Diamonds.... overview - Metals Minerals and markets session, Sunday Prospectors and Developers Association of Canada (PDAC)Prospectors and Developers Association of Canada (PDAC) 2001, 1p. abstractGlobalDiamond - market brief overview
DS2002-0992
2002
Manson, M.Manson, M.Diamond marketing: opportunities for the new Canadian productionUniversity of Western Ontario, SEG Student Chapter, March 8, p. 21. ( 1p). abstractNorthwest TerritoriesDiamond - markets ( brief), Aber, Diavik
DS200512-0682
2005
Manson, M.Manson, M.95-2 bulk sample Timiskaming kimberlite cluster, Ontario.British Columbia & Yukon Mineral Exploration Roundup, Jan.24-27th., p. 79-81.Canada, Ontario, Lake TemiskamingNews item - brief overview, Contact Diamonds
DS200812-0711
2007
Manson, M.Manson, M.The Renard project: Quebec's first diamond mine.Quebec Exploration Conference, Nov. 28, 1p. abstract onlyCanada, QuebecNews item - Stornoway
DS201212-0441
2012
Manson, M.Manson, M.Diamonds - commodity overview.PDAC 2012, abstractGlobalEconomics
DS201501-0018
2015
Manson, M.Manson, M.Jacques Cartier's legacy: the Renard diamond project under construction.PDAC 2015, 1p. AbstractCanada, QuebecDeposit - Renard
DS1992-0991
1992
Manson, M.L.Manson, M.L., Halls, H.C.The geometry and sense of post-Keweenawan faults in eastern Lake Superior:implications for models of rift developmentEos Transactions, Vol. 73, No. 14, April 7, supplement abstracts p. 320OntarioMidcontinent Rift, Structure -faults
DS1994-1098
1994
Manson, M.L.Manson, M.L., Halls, H.C.Post Keweenwan compressional faults in eastern Lake Superior region and their tectonic significance.Canadian Journal of Earth Sciences, Vol. 31, No. 4, April pp. 640-651.Ontario, MichiganGeophysics -seismics, Tectonics -Midcontinent rift
DS1997-0728
1997
Manson, M.L.Manson, M.L., Halls, H.C.Proterozoic reactivation of southern Superior Province and its role in the evolution of Midcontinent Rift.Canadian Journal of Earth Sciences, Vol. 34, No. 4, April, pp. 562-575.Michigan, WisconsinRifting, tectonics, Kapuskasing structural zone
DS200712-0679
2006
Manson, N.B.Manson, N.B., Harrison, J.P., Sellars, M.J.Nitrogen vacancy center in diamond: model of the electronic structure and associated dynamics.Physical Review Letters, Vol. 74, 10, 104303 ingenta 1064798716TechnologyDiamond mineralogy
DS1991-1046
1991
Manson, V.Manson, V.Proportion considerations in round brilliantsInternational Gemological Symposium, June 20-24, 1991 Los Angeles, Gems and Gemology, Vol. 27, Spring, Program p. 4GlobalDiamond cutting
DS1995-1158
1995
Manson Creek ResourcesManson Creek ResourcesDiamond discovery in eastern Arctic...Parker LakeManson Creek Resources Ltd., Feb. 9, 1p.Northwest TerritoriesNews item -press release
DS202205-0703
2021
Mansoor, M.Mansoor, M., Mansoor, M., Mansoor, M., Aksoy, A., Seyhan, S.N., Yildirim, B., Tahiri, A., Solak, N., Kazmanli, K., Er, Z., Czelej, K., Urgen, M.Ab-nitro calculation of point defect equilibria during heat treatment: nitrogen, hydrogen, and silicon doped diamond.Researchgate preprint Istanbul Technical University , 18p. PdfGlobaldiamond morphology

Abstract: Point defects are responsible for a wide range of optoelectronic properties in materials, making it crucial to engineer their concentrations for novel materials design. However, considering the plethora of defects in co-doped semiconducting and dielectric materials and the dependence of defect formation energies on heat treatment parameters, process design based on an experimental trial and error approach is not an efficient strategy. This makes it necessary to explore computational pathways for predicting defect equilibria during heat treatments. The accumulated experimental knowledge on defect transformations in diamond is unparalleled. Therefore, diamond is an excellent material for benchmarking computational approaches. By considering nitrogen, hydrogen, and silicon doped diamond as a model system, we have investigated the pressure dependence of defect formation energies and calculated the defect equilibria during heat treatment of diamond through ab-initio calculations. We have plotted monolithic-Kröger-Vink diagrams for various defects, representing defect concentrations based on process parameters, such as temperature and partial pressure of gases used during heat treatments of diamond. The method demonstrated predicts the majority of experimental data, such as nitrogen aggregation path leading towards the formation of the B center, annealing of the B, H3, N3, and NVHx centers at ultra high temperatures, the thermal stability of the SiV center, and temperature dependence of NV concentration. We demonstrate the possibility of designing heat treatments for a wide range of semiconducting and dielectric materials by using a relatively inexpensive yet robust first principles approach, significantly accelerating defect engineering and high-throughput novel materials design.
DS202205-0703
2021
Mansoor, M.Mansoor, M., Mansoor, M., Mansoor, M., Aksoy, A., Seyhan, S.N., Yildirim, B., Tahiri, A., Solak, N., Kazmanli, K., Er, Z., Czelej, K., Urgen, M.Ab-nitro calculation of point defect equilibria during heat treatment: nitrogen, hydrogen, and silicon doped diamond.Researchgate preprint Istanbul Technical University , 18p. PdfGlobaldiamond morphology

Abstract: Point defects are responsible for a wide range of optoelectronic properties in materials, making it crucial to engineer their concentrations for novel materials design. However, considering the plethora of defects in co-doped semiconducting and dielectric materials and the dependence of defect formation energies on heat treatment parameters, process design based on an experimental trial and error approach is not an efficient strategy. This makes it necessary to explore computational pathways for predicting defect equilibria during heat treatments. The accumulated experimental knowledge on defect transformations in diamond is unparalleled. Therefore, diamond is an excellent material for benchmarking computational approaches. By considering nitrogen, hydrogen, and silicon doped diamond as a model system, we have investigated the pressure dependence of defect formation energies and calculated the defect equilibria during heat treatment of diamond through ab-initio calculations. We have plotted monolithic-Kröger-Vink diagrams for various defects, representing defect concentrations based on process parameters, such as temperature and partial pressure of gases used during heat treatments of diamond. The method demonstrated predicts the majority of experimental data, such as nitrogen aggregation path leading towards the formation of the B center, annealing of the B, H3, N3, and NVHx centers at ultra high temperatures, the thermal stability of the SiV center, and temperature dependence of NV concentration. We demonstrate the possibility of designing heat treatments for a wide range of semiconducting and dielectric materials by using a relatively inexpensive yet robust first principles approach, significantly accelerating defect engineering and high-throughput novel materials design.
DS202205-0703
2021
Mansoor, M.Mansoor, M., Mansoor, M., Mansoor, M., Aksoy, A., Seyhan, S.N., Yildirim, B., Tahiri, A., Solak, N., Kazmanli, K., Er, Z., Czelej, K., Urgen, M.Ab-nitro calculation of point defect equilibria during heat treatment: nitrogen, hydrogen, and silicon doped diamond.Researchgate preprint Istanbul Technical University , 18p. PdfGlobaldiamond morphology

Abstract: Point defects are responsible for a wide range of optoelectronic properties in materials, making it crucial to engineer their concentrations for novel materials design. However, considering the plethora of defects in co-doped semiconducting and dielectric materials and the dependence of defect formation energies on heat treatment parameters, process design based on an experimental trial and error approach is not an efficient strategy. This makes it necessary to explore computational pathways for predicting defect equilibria during heat treatments. The accumulated experimental knowledge on defect transformations in diamond is unparalleled. Therefore, diamond is an excellent material for benchmarking computational approaches. By considering nitrogen, hydrogen, and silicon doped diamond as a model system, we have investigated the pressure dependence of defect formation energies and calculated the defect equilibria during heat treatment of diamond through ab-initio calculations. We have plotted monolithic-Kröger-Vink diagrams for various defects, representing defect concentrations based on process parameters, such as temperature and partial pressure of gases used during heat treatments of diamond. The method demonstrated predicts the majority of experimental data, such as nitrogen aggregation path leading towards the formation of the B center, annealing of the B, H3, N3, and NVHx centers at ultra high temperatures, the thermal stability of the SiV center, and temperature dependence of NV concentration. We demonstrate the possibility of designing heat treatments for a wide range of semiconducting and dielectric materials by using a relatively inexpensive yet robust first principles approach, significantly accelerating defect engineering and high-throughput novel materials design.
DS1988-0438
1988
Manspeizer, W.Manspeizer, W.Continental break up and origin of the Atlantic ocean and passivemarginsElsevier, Dev. in Geotectonics No. 22, 998p. $ 294.75 United StatesAfrica, North AmericaPlate tectonics, Outline of book
DS1983-0534
1983
Mansure, A.J.Reiter, M., Mansure, A.J.Geothermal Studies in the San Juan Basin and the Four Corners Area of the Colorado Plateau. I. Terrestrial Heat Flow Measurements.Tectonophysics, Vol. 91, PP. 233-251.GlobalRocky Mountians, Geophysics
DS2000-0970
2000
Mantarri, I.Vaisanen, M., Mantarri, I., Kriegsman, L.M., Holtta, P.Tectonic setting of post collisional magmatism in the Paleoproterozoic Svecofennian Orogen, southwest Finland.Lithos, Vol. 54, No. 1-2, Oct. pp. 63-81.FinlandTectonics, mantle enrichment, magmatism
DS201412-0006
2014
Manthei, C.Alvarez-Valero, A.M., Jagoutz, O., Stanley, J., Manthei, C., Ali Moukadiri, A., Piasecki, A.Crustal attenuation as a tracer for the emplacement of the Beni Bousera ultramafic massif ( Betico-Rifean belt).Geological Society of America Bulletin, Vol. 126, no. 11/12, pp. 1614-1624.Africa, MoroccoBeniBoussera
DS201012-0472
2010
Manthei, C.D.Manthei, C.D., Ducea, M.N., Girardi, J.D., Patchett, P.Isotopic and geochemical evidence for a recent transition in mantle chemistry beneath the western Canadian Cordillera.Journal of Geophysical Research, Vol. 115, B2, B202204.Canada, Alberta, saskatchewan, Northwest TerritoriesGeochemistry
DS200812-1299
2008
Manthilake, G.Yoshina, T., Manthilake, G., Matsuzaki, T., Katsura, T.Dry mantle transition zone inferred from the conductivity of wadsleyite and ringwoodite.Nature, Vol. 451, 7176, pp. 326-329.MantleGeochemistry
DS201012-0347
2009
Manthilake, G.Katsura, T., Yoshino, T., Manthilake, G., Matsuzaki, T.Electrical conductivity of the major upper mantle minerals: a review.Russian Geology and Geophysics, Vol. 50, 12, pp. 1139-1145.MantleGeophysics - seismics
DS201412-0127
2014
Manthilake, G.Chheda, T.D., Mookherjee, M., Mainprice, D., Dos Santos, A.M., Molaison, J.J., Chantel, J., Manthilake, G., Bassett, W.A.Structure and elasticity of phlogopite under compression: geophysical implications.Physics of the Earth and Planetary Interiors, Vol. 233, pp. 1-12.MantleGeophysics
DS201412-0336
2014
Manthilake, G.Hammouda, T., Chantel, J., Manthilake, G., Guignard, J., Crichton, W.Hot mantle geotherms stabilize calcic carbonatite magmas up to the surface.Geology, Vol. 42, no. 10, pp. 911-914.MantleCarbonatite
DS201705-0864
2017
Manthilake, G.Novella, D., Dolejs, D., Myhill, R., Pamato, M.G., Manthilake, G., Frost, D.J.Melting phase relations in the systems Mg2SiO4-H2O and MgSiO3-H2O and the formation of hydrous melts.Geochimica et Cosmochimica Acta, Vol. 204, pp. 68-82.MantleMelting

Abstract: High-pressure and high-temperature melting experiments were conducted in the systems Mg2SiO4-H2O and MgSiO3-H2O at 6 and 13 GPa and between 1150 and 1900 °C in order to investigate the effect of H2O on melting relations of forsterite and enstatite. The liquidus curves in both binary systems were constrained and the experimental results were interpreted using a thermodynamic model based on the homogeneous melt speciation equilibrium, H2O + O2? = 2OH?, where water in the melt is present as both molecular H2O and OH? groups bonded to silicate polyhedra. The liquidus depression as a function of melt H2O concentration is predicted using a cryoscopic equation with the experimental data being reproduced by adjusting the water speciation equilibrium constant. Application of this model reveals that in hydrous MgSiO3 melts at 6 and 13 GPa and in hydrous Mg2SiO4 melts at 6 GPa, water mainly dissociates into OH? groups in the melt structure. A temperature dependent equilibrium constant is necessary to reproduce the data, however, implying that molecular H2O becomes more important in the melt with decreasing temperature. The data for hydrous forsterite melting at 13 GPa are inconclusive due to uncertainties in the anhydrous melting temperature at these conditions. When applied to results on natural peridotite melt systems at similar conditions, the same model infers the presence mainly of molecular H2O, implying a significant difference in physicochemical behaviour between simple and complex hydrous melt systems. As pressures increase along a typical adiabat towards the base of the upper mantle, both simple and complex melting results imply that a hydrous melt fraction would decrease, given a fixed mantle H2O content. Consequently, the effect of pressure on the depression of melting due to H2O could not cause an increase in the proportion, and hence seismic visibility, of melts towards the base of the upper mantle.
DS201707-1309
2017
Manthilake, G.Bouhifd, M.A., Clesi, V., Boujibar, A., Cartier, C., Hammouda, T., Boyet, M., Manthilake, G., Monteux, J., Andrault, D.Silicate melts during the Earth's core formation.Chemical Geology, Vol. 461, pp. 128-139.Mantlemelting

Abstract: Accretion from primordial material and its subsequent differentiation into a planet with core and mantle are fundamental problems in terrestrial and solar system. Many of the questions about the processes, although well developed as model scenarios over the last few decades, are still open and much debated. In the early Earth, during its formation and differentiation into rocky mantle and iron-rich core, it is likely that silicate melts played an important part in shaping the Earth's main reservoirs as we know them today. Here, we review several recent results in a deep magma ocean scenario that give tight constraints on the early evolution of our planet. These results include the behaviour of some siderophile elements (Ni and Fe), lithophile elements (Nb and Ta) and one volatile element (Helium) during Earth's core formation. We will also discuss the melting and crystallization of an early magma ocean, and the implications on the general feature of core-mantle separation and the depth of the magma ocean. The incorporation of Fe2 + and Fe3 + in bridgmanite during magma ocean crystallization is also discussed. All the examples presented here highlight the importance of the prevailing conditions during the earliest time of Earth's history in determining the composition and dynamic history of our planet.
DS201711-2499
2017
Manthilake, G.Andrault, D., Bolfan-Casanova, N., Bouhifd, M.A., Boujibar, A., Garbarino, G., Manthilake, G., Mezouar, M., Monteux, J., Parisiades, P., Pesce, G.Toward a coherent model for the melting behaviour of the deep Earth's mantle.Physics of the Earth and Planetary Interiors, Vol. 265, pp. 67-81.Mantlemelting

Abstract: Knowledge of melting properties is critical to predict the nature and the fate of melts produced in the deep mantle. Early in the Earth’s history, melting properties controlled the magma ocean crystallization, which potentially induced chemical segregation in distinct reservoirs. Today, partial melting most probably occurs in the lowermost mantle as well as at mid upper-mantle depths, which control important aspects of mantle dynamics, including some types of volcanism. Unfortunately, despite major experimental and theoretical efforts, major controversies remain about several aspects of mantle melting. For example, the liquidus of the mantle was reported (for peridotitic or chondritic-type composition) with a temperature difference of ?1000 K at high mantle depths. Also, the Fe partitioning coefficient (DFeBg/melt) between bridgmanite (Bg, the major lower mantle mineral) and a melt was reported between ?0.1 and ?0.5, for a mantle depth of ?2000 km. Until now, these uncertainties had prevented the construction of a coherent picture of the melting behavior of the deep mantle. In this article, we perform a critical review of previous works and develop a coherent, semi-quantitative, model. We first address the melting curve of Bg with the help of original experimental measurements, which yields a constraint on the volume change upon melting (?Vm). Secondly, we apply a basic thermodynamical approach to discuss the melting behavior of mineralogical assemblages made of fractions of Bg, CaSiO3-perovskite and (Mg,Fe)O-ferropericlase. Our analysis yields quantitative constraints on the SiO2-content in the pseudo-eutectic melt and the degree of partial melting (F) as a function of pressure, temperature and mantle composition; For examples, we find that F could be more than 40% at the solidus temperature, except if the presence of volatile elements induces incipient melting. We then discuss the melt buoyancy in a partial molten lower mantle as a function of pressure, F and DFeBg/melt. In the lower mantle, density inversions (i.e. sinking melts) appear to be restricted to low F values and highest mantle pressures. The coherent melting model has direct geophysical implications: (i) in the early Earth, the magma ocean crystallization could not occur for a core temperature higher than ?5400 K at the core-mantle boundary (CMB). This temperature corresponds to the melting of pure Bg at 135 GPa. For a mantle composition more realistic than pure Bg, the right CMB temperature for magma ocean crystallization could have been as low as ?4400 K. (ii) There are converging arguments for the formation of a relatively homogeneous mantle after magma ocean crystallization. In particular, we predict the bulk crystallization of a relatively large mantle fraction, when the temperature becomes lower than the pseudo-eutectic temperature. Some chemical segregation could still be possible as a result of some Bg segregation in the lowermost mantle during the first stage of the magma ocean crystallization, and due to a much later descent of very low F, Fe-enriched, melts toward the CMB. (iii) The descent of such melts could still take place today. There formation should to be related to incipient mantle melting due to the presence of volatile elements. Even though, these melts can only be denser than the mantle (at high mantle depths) if the controversial value of DFeBg/melt is indeed as low as suggested by some experimental studies. This type of melts could contribute to produce ultra-low seismic velocity anomalies in the lowermost mantle.
DS201803-0432
2018
Manthilake, G.Andrault, D., Pesce, G., Manthilake, G., Monteux, J., Volfan-Casanova, N., Chantel, J. , Novella, D., Guignot, N., King, A., Itie, J-P., Hennet, L.An archean mushy mantle.Nature Geoscience, Vol. 11, 2, pp. 85-86.Mantlegeodynamics

Abstract: Experimental data reveal that Earth’s mantle melts more readily than previously thought, and may have remained mushy until two to three billion years ago.
DS201910-2246
2019
Manthilake, G.Bureau, H., Raepsat, V., Esteve, I., Armstrong, K., Manthilake, G.Replicate mantle diamonds.Goldschmidt2019, 1p. AbstractMantlediamond genesis

Abstract: Still today, diamond growth in the mantle is difficult to understand. It may implicate different processes but there is an agreement to involve fluids as diamonds parents. The composition of these fluids is supposed to be variable depending of the the settings and depths. Natural diamonds also exhibit dissolution features, possibly mantle-derived and not only due to kimberlite-induced resorption during magma ascent [1]. We present experimental results devoted to understand diamond growth versus dissolution mechanisms in the lithosphere. Experiments are performed using multianvil presses at 7 GPa, 1300-1675°C for a few hours (4 to 27 hrs). As starting materials we use mixtures of water, carbonates, natural lherzolite or MORB, graphite and diamonds seeds resulting in hydrous-carbonate-silicate fluids at high pressure and temperature. For similar pressure and temperature conditions, results show that diamonds are formed or dissolved in these fluids, depending on the redox conditions. Focussed ion beam preparations of the diamonds evidence that when they grow, they trap multi-phased inclusions similar to those observed in fibrous, coated and monocrystalline natural diamonds, in agreement with previous studies [2-4].
DS202204-0533
2022
Manthilake, G.Peng, Y., Manthilake, G., Mookherjee, M.Electrical conductivity of metasomatized lithology in subcontinental lithosphere.American Mineralogist, Vol. 107, pp. 343-349.Mantlemetasomatism

Abstract: A plausible origin of the seismically observed mid-lithospheric discontinuity (MLD) in the subcontinental lithosphere is mantle metasomatism. The metasomatized mantle is likely to stabilize hydrous phases such as amphiboles. The existing electrical conductivity data on amphiboles vary significantly. The electrical conductivity of hornblendite is much higher than that of tremolite. Thus, if hornblendite truly represents the amphibole varieties in MLD regions, then it is likely that amphibole will cause high electrical conductivity anomalies at MLD depths. However, this is inconsistent with the magnetotelluric observations across MLD depths. Hence, to better understand this discrepancy in electrical conductivity data of amphiboles and to evaluate whether MLD could be caused by metasomatism, we determined the electrical conductivity of a natural metasomatized rock sample. The metasomatized rock sample consists of ~87% diopside pyroxene, ~9% sodium-bearing tremolite amphibole, and ~3% albite feldspar. We collected the electrical conductivity data at ~3.0 GPa, i.e., the depth relevant to MLD. We also spanned a temperature range between 400 to 1000 K. We found that the electrical conductivity of this metasomatized rock sample increases with temperature. The temperature dependence of the electrical conductivity exhibits two distinct regimes. At low temperatures <700 K, the electrical conductivity is dominated by the conduction in the solid state. At temperatures >775 K, the conductivity increases, and it is likely to be dominated by the conduction of aqueous fluids due to partial dehydration. The main distinction between the current study and the prior studies on the electrical conductivity of amphiboles or amphibole-bearing rocks is the sodium (Na) content in amphiboles of the assemblage. Moreover, it is likely that the higher Na content in amphiboles leads to higher electrical conductivity. Pargasite and edenite amphiboles are the most common amphibole varieties in the metasomatized mantle, and our study on Na-bearing tremolite is the closest analog of these amphiboles. Comparison of the electrical conductivity results with the magnetotelluric observations constrains the amphibole abundance at MLD depths to <1.5%. Such a low-modal proportion of amphiboles could only reduce the seismic shear wave velocity by 0.4-0.5%, which is significantly lower than the observed velocity reduction of 2-6%. Thus, it might be challenging to explain both seismic and magnetotelluric observations at MLD simultaneously.
DS200812-0712
2008
Manthilake, M.A.G.M.Manthilake, M.A.G.M., Sawada, Y., Sakai, S.Genesis and evolution of Eppawala carbonatites, Sri Lanka.Journal of Asian Earth Sciences, Vol. 32, 1,feb. 15, pp. 66-75.Asia, Sri LankaCarbonatite
DS201412-0872
2014
Manthilake, M.A.G.M.Soustelle, V., Walte, N.P., Manthilake, M.A.G.M., Frost, D.J.Melt migration and melt rock reactions in the deforming Earth's upper mantle: experiments at high pressure and temperature.Geology, Vol. 42, pp. 83-86.MantleMelting
DS201606-1110
2016
Manthos, V.Rizo, H., Walker, R.J., Carlson, R.W., Horan, M.F., Mukhopadhyay, S., Manthos, V., Francis, D., Jackson, M.G.Preservation of Earth forming events in the tungsten isotopic composition of modern flood basalts…… ancient rocksScience, Vol. 352, no. 6287, May 13, pp. 809-812.Canada, Nunavut, Baffin IslandGeochronology

Abstract: How much of Earth's compositional variation dates to processes that occurred during planet formation remains an unanswered question. High-precision tungsten isotopic data from rocks from two large igneous provinces, the North Atlantic Igneous Province and the Ontong Java Plateau, reveal preservation to the Phanerozoic of tungsten isotopic heterogeneities in the mantle. These heterogeneities, caused by the decay of hafnium-182 in mantle domains with high hafnium/tungsten ratios, were created during the first ~50 million years of solar system history, indicating that portions of the mantle that formed during Earth’s primary accretionary period have survived to the present
DS2002-1530
2002
MantillaSpencer, R.M., Montenegro, J.L., Gaibor,Perez,MantillaThe Portovelo Zaruma mining camp: southwest Ecuador: porphyry and epithermal environments.Seg Newsletter, No. 49, April, pp. 1,8-14.EcuadorCopper, gold, Deposit - Portovelo Zaruma, R-Nivel, Muluncay
DS1960-0573
1965
Manton, W.I.Manton, W.I.A Rubidium Strontium Study of the Lebombo Nuanetsi Igneous Province Southern Africa.Report ON SCI. and EDUC. PROGRAMS 1964-1965 GRAD. RES. CENTRE O, ZimbabweIsotope, Related Rocks
DS1960-0985
1968
Manton, W.I.Manton, W.I.The Origin of Associated Basic and Acid Rocks in the Lebombo Nuanetsi Igneous Province, Southern Africa As Implied by Strontium Isotopes.Journal of PETROLOGY, Vol. 9, No. 1, PP. 23-29.South AfricaRelated Rocks, Geology
DS1960-1163
1969
Manton, W.I.Manton, W.I.Isotopic Composition of Lead Strontium in Nodules from Roberts Victor Mine, South Africa.American Geophysical Union (AGU) Transactions, Vol. 50, No. 4, P. 343. (abstract.).South AfricaIsotope
DS1970-0344
1971
Manton, W.I.Manton, W.I., Tatsumoto, M.Some Lead and Strontium Isotopic Measurements on Eclogites from the Roberts Victor Mine, South Africa.Earth and Planetary Science Letters, Vol. 10, No. 2, PP. 217-226.South AfricaIsotope., Lead, Strontium
DS1981-0005
1981
Manton, W.I.Allsop, H.L., Bristown, J.W., Manton, W.I., Cleverly, R.W.Rubidium-strontium Geochronology of the Lebombo VolcanicsGeocongress '81, South African Geodynamics Project., ABSTRACT VOLUME, PP. 1-2.GlobalDokolwayo, Lembo Volcanics
DS1986-0512
1986
Manton, W.I.MacGregor, I.D., Manton, W.I.The Roberts Victor eclogites: ancient oceanic crustJournal of Geophysical Research, Pt. B, Paper No. 6B5997 (abstract.)South AfricaEclogite
DS1986-0513
1986
Manton, W.I.MacGregor, I.D., Manton, W.I.Roberts Victor eclogites: ancient oceanic crustJournal of Geophysical Research, Vol. 91, No. b14, December 10, pp. 14063-14079South AfricaEclogites, Genesis
DS201803-0479
2017
Mantovani, F.Strati, V., Wipperfurth, S.A., Baldoncini, M., McDonough, W.F., Mantovani, F.Perceiving the crust in 3-D: a model integrating geological, geochemical and geophysical data.Geochemistry, Geophysics, Geosystems G3, pp. 4326-Mantlegeophysics

Abstract: Regional characterization of the continental crust has classically been performed through either geologic mapping, geochemical sampling, or geophysical surveys. Rarely are these techniques fully integrated, due to limits of data coverage, quality, and/or incompatible data sets. We combine geologic observations, geochemical sampling, and geophysical surveys to create a coherent 3-D geologic model of a 50 × 50 km upper crustal region surrounding the SNOLAB underground physics laboratory in Canada, which includes the Southern Province, the Superior Province, the Sudbury Structure, and the Grenville Front Tectonic Zone. Nine representative aggregate units of exposed lithologies are geologically characterized, geophysically constrained, and probed with 109 rock samples supported by compiled geochemical databases. A detailed study of the lognormal distributions of U and Th abundances and of their correlation permits a bivariate analysis for a robust treatment of the uncertainties. A downloadable 3-D numerical model of U and Th distribution defines an average heat production of math formula µW/m3, and predicts a contribution of math formula TNU (a Terrestrial Neutrino Unit is one geoneutrino event per 1032 target protons per year) out of a crustal geoneutrino signal of math formula TNU. The relatively high local crust geoneutrino signal together with its large variability strongly restrict the SNO+ capability of experimentally discriminating among BSE compositional models of the mantle. Future work to constrain the crustal heat production and the geoneutrino signal at SNO+ will be inefficient without more detailed geophysical characterization of the 3-D structure of the heterogeneous Huronian Supergroup, which contributes the largest uncertainty to the calculation.
DS1988-0294
1988
Mantovani, M.Hawkesworth, C.J., Mantovani, M., Peate, D.Lithospheric remobilization during Parana CFB magmatismJournal of Petrology, Special Volume 1988- Oceanic and Continental, pp. 205-224Brazil, Paraguay, ArgentinaMantle, Chemistry
DS201706-1093
2017
Mantovani, M.Louro, V., Cawood, P., Mantovani, M., Biondo Ribeiro, V.Tectonic insights of the southwest Amazon craton from geophysical, geochemical and mineralogical dat a of Figueira Branca mafic-ultramafic suite, Brazil.Tectonophysics, Vol. 708, pp. 96-107.South America, Brazilcraton - Amazon

Abstract: The Figueira Branca Suite is a layered mafic-ultramafic complex in the Jauru Terrane, southwest Amazon Craton. New lithological, geochemical, gamma-ray and potential field data, integrated with geological, isotope and paleomagnetic data are used to characterize this pulse of Mesoproterozoic extension-related magmatism. The Figueira Branca Suite formed through juvenile magma emplacement into the crust at 1425 Ma, coeval with the later stages of the Santa Helena Orogen. Gabbros and peridotite-gabbros display increasing enrichment of LREE, interpreted as evidence of progressive fractionation of the magma. Magnetic and gamma-ray data delimit the extent of magmatism within the suite to four bodies to the north of Indiavaí city. Modelling gravity and magnetic field data indicate that the anomalous sources are close to the surface or outcropping. These intrusions trend northwest over 8 km, with significant remanent magnetization that is consistent with published direction obtained through paleomagnetic data. The emplacement, mineralogy and geochemical signature point towards a back-arc extension tectonic framework in the later stages of the Santa Helena Orogen.
DS1994-1099
1994
Mantovani, M.S.M.Mantovani, M.S.M., Stewart, K., Turner, S., Hawkesworth, C.Duration of Parana magmatism and implications for the evolution and source regions of cont. flood basalts.International Symposium Upper Mantle, Aug. 14-19, 1994, Extended abstracts pp. 47-48.BrazilMagma, Flood basalts
DS1999-0442
1999
Mantovani, M.S.M.Mantovani, M.S.M., Shukowsky, W., De Freitas, S.R.C.Tectonic pattern of South America inferred from tidal gravity anomaliesPhysical Earth and Planetary Interiors, Vol. 114, No. 1-2, July 6, pp. 91-100.South AmericaGeophysics - gravity
DS2000-0503
2000
Mantovani, M.S.M.Kirstein, L.A., Peate, D.W., Mantovani, M.S.M.Early Cretaceous basaltic and rhyolitic magmatism in southern Uruguay: associated opening South AtlanticJournal of Petrology, Vol. 41, No. 9, Sept. pp. 1413-38.Uruguay, South AmericaMagmatism
DS2001-0730
2001
Mantovani, M.S.M.Mantovani, M.S.M., De Freitas, S.R.C., Shukowsky, W.Tidal gravity anomalies as a tool to measure rheological properties of the continental lithosphereJournal of South American Earth Sciences, Vol. 14, No. 1, Apr. pp. 1-14.South AmericaGeophysics - gravity, Geodynamics
DS200512-0683
2005
Mantovani, M.S.M.Mantovani, M.S.M., De Brito Neves, B.B.The Paranapanema lithospheric block: its importance for Proterozoic (Rodinia, Gondwana) supercontinent theories.Gondwana Research, Vol. 8, 3, pp. 303-315.South America, BrazilTectonics, Amazon, Sao Francisco, La Plata cratons
DS200612-0860
2005
Mantovani, M.S.M.Mantovani, M.S.M., Rugenski, A., Diogo, L.A., Shukowsky, W.Integrated geophysical investigation of a possible new alkaline occurrence in SE Brazil.Journal of South American Earth Sciences, Vol. 20, 3, Dec. pp. 259-266.South America, BrazilGeophysics - magnetics, gravity
DS201212-0442
2012
Mantovani, M.S.M.Marangoni, Y.R., Mantovani, M.S.M.Geophysical signatures of the alkaline intrusions bordering the Parana Basin.Journal of South American Earth Sciences, in press available, 48p.South America, Paraguay, BrazilGeophysics - magnetics
DS201312-0573
2013
Mantovani, M.S.M.Maragoni, Y.R., Mantovani, M.S.M.Geophysical signatures of the alkaline intrusions bordering on the Parana Bain.Journal of South American Earth Sciences, Vol. 41, pp. 83-98.South America, BrazilGeophysics - alkaline
DS201507-0323
2016
Mantovani, M.S.M.Mantovani, M.S.M., Louro, V.H.A., Ribeiro, V.B., Requejo, H.S., dos Santos, R.P.Z.Geophysical analysis of Catalao 1 alkaline carbonatite complex in Goias, Brazil.Geophysical Prospecting, Vol. 64, pp. 216-227.South America, BrazilDeposit - Catalao
DS201602-0222
2016
Mantovani, M.S.M.Mantovani, M.S.M., Louro, V.H.A., Ribeiro, V.B., Requejo, H.S., Santos, R.P.Z. dos.Geophysical analysis of Catalano 1 alkaline carbonatite complex in Goias, Brazil.Geophysical Prospecting, Vol. 64, 1, pp. 216-227.South America, BrazilDeposit - Catalano 1
DS1993-1209
1993
Mantovani, M.SM.Peate, D.W., Hawkesworth, C.J, Mantovani, M.SM.Chemical stratigraphy of the Parana lavas (South America): classification of magma types and their spatial distributionBulletin Volcanology, Vol. 55, pp. 119-139South AmericaFlood basalts, Geochemistry
DS2002-0402
2002
Manttari, I.Downes, H., Peltonen, P., Manttari, I., Sharkov, E.V.Proterozoic zircon ages from lower crust granulite xenoliths, Kola Peninsula, Russia: evidence for crustal growth and reworking.Journal of the Geological Society of London, Vol. 159, 2, pp. 485-488.Russia, Kola PeninsulaBlank
DS2002-1240
2002
Manttari, I.Peltonen, P., Manttari, I.An ion microprobe U Th Pb study of zircon xenocrysts from the Lahtojoki kimberlite pipe eastern Finland.Geological Society of Finland Bulletin, Vol. 73, 1/2, pp. 47-58.FinlandGeochronology, Deposit - Lahtojoki
DS2002-1628
2002
Manttari, I.Vaisanen, M., Manttari, I., Holtta, P.Svecofennian magmatic and metamorphic evolution in southwestern FIn land as revealed by U Pb zircon SIMS geochronology.Precambrian Research, Vol. 116, No.1-2, pp. 111-27.FinlandMagmatism, Geochronology
DS2003-1061
2003
Manttari, I.Peltonen, P., Manttari, I., Huhma, H., Kontinen, A.Archean zircons from the mantle: the Jormua ophiolite revisitedGeology, Vol. 31, 7, July, pp. 645-8.EuropeGeochronology
DS200412-0478
2002
Manttari, I.Downes, H., Peltonen, P., Manttari, I., Sharkov, E.V.Proterozoic zircon ages from lower crust granulite xenoliths, Kola Peninsula, Russia: evidence for crustal growth and reworking.Journal of the Geological Society, Vol. 159, 2, pp. 485-488.Russia, Kola PeninsulaGeochronology
DS200412-1521
2003
Manttari, I.Peltonen, P., Manttari, I., Huhma, H., Kontinen, A.Archean zircons from the mantle: the Jormua ophiolite revisited.Geology, Vol. 31, 7, July, pp. 645-8.EuropeGeochronology
DS200612-1069
2006
Manttari, I.Peltonen, P., Manttari, I., Huhma, H., Whitehouse, M.J.Multi stage origin of the lower crust of the Karelian craton from 3.5 to 1.7 Ga based on isotopic ages of kimberlite derived mafic granulite xenoliths.Precambrian Research, Vol. 147, 1-2, June 10, pp. 107-123.Europe, FinlandGeochronology, kimberlite, mantle plume, craton
DS201805-0970
2001
Manttari, I.Peltonen, P., Manttari, I.An ion microprobe U Th Pb study of zircon xenocrysts from the Lahtojoki kimberlite pipe, eastern Finland. NOTE Date of publ.Bulletin of the Geological Survey of Finland, Vol. 73, 1-2, pp. 47-58.Europe, Finlanddeposit - Lahtojoki

Abstract: Eleven relatively large (diameter 1-2 mm) zircon grains extracted from the Lahtojoki kimberlite pipe (Eastern Finland Kimberlite Province) have been analysed by the ion microprobe NORDSIM for their U- and Pb- isotopic composition. The 207Pb/206Pb ages fall into two concordant age groups: 2.7 Ga and 1.8 Ga. Discordant ages between these two groups are believed to result from partial resetting of Archaean grains in the 1.8 Ga thermal event. Since other datingmethods imply that kimberlites emplaced c. 0.6 Ga ago it is clear that the analysed zircons are xenocrysts inherited from older sources and do not provide the age of the kimberlite magmatism. Their unusual size and morphology, together with very low U- and Pb-concentrations, suggest, however, that these zircon grains are not derived from typical Archaean gneisses. More likely, they originate from lower crustal mafic pegmatites and from hydrous coarse-grained veins within the uppermost lithospheric mantle. The predominance of 1.8 Ga old xenocrystic grains, together with the recovery of mafic granulite xenoliths of similar age in the kimberlites (Hölttä et al. 2000), emphasises the importance of post-collisional lower crustal growth and reworking in central Fennoscandia.
DS200412-0066
2004
Manu, J.Asiedu, D.K., Dampare, S.B., Sakyi, P.A., Banoeng Yakubo, B., Osae, S., Nyarko, B.J.B., Manu, J.Geochemistry of Paleoproterozoic metasedimentary rocks from the Birim Diamondiferous field: implications for provenance and crusGeochemical Journal, Vol. 38, 3, pp. 215-228.Africa, GhanaGeochemistry - Archean Proterozoic boundary
DS201712-2727
2018
Manu Prasanth, M.P.Santosh, M., Hari, K.R., He, X-F., Han, Y-S., Manu Prasanth, M.P.Oldest lamproites from Peninsular India track the onset of Paleoproterozoic plume induced rifting and the birth of Large Igneous Province.Gondwana Research, Vol. 55, pp. 1-20.Indialamproites - Nuapada

Abstract: Potassic and ultrapotassic magmatism from deep lithospheric sources in intra-cratonic settings can be the signal of subsequent voluminous mafic magmatism and the formation of Large Igneous Provinces (LIPs) triggered by mantle plumes. Here we report for the first time, precise zircon U-Pb age data from a suite of lamproites in the Bastar Craton of central India that mark the onset of Paleoproterozoic rifting and culminating in the formation of extensive mafic dyke swarms as the bar codes of one of the major LIP events during the Precambrian evolution of the Indian shield. The lamproites from the Nuapada field occur as dismembered dykes and are composed of phenocrysts and microphenocrysts of altered olivine together with microphenocrysts of phlogopite and magnetite within a groundmass of chlorite and calcite with accessory rutile, apatite and zircon. The rocks compositionally correspond to olivine phlogopite lamproite and phlogopite lamproite. Geochemical features of the lamproites correlate with their counterparts in Peninsular India and other similar suites elsewhere in the world related to rift settings, and also indicate OIB-like magma source. The associated syenite shows subduction-related features, possibly generated in a post-collisional setting. Magmatic zircon grains with high Th/U ratios in the syenite from the Nuapada lamproite form a coherent group with an upper intercept age of 2473 ± 8 Ma representing the timing of emplacement of the magma. Zircon grains in three lamproite samples yield four distinct age groups at ca. 2.4 Ga, 2.2 Ga, 2.0 Ga and 0.8 Ga. The 2.4 Ga group corresponds to xenocrysts entrained from the syenite whereas the 2.2 Ga group is considered to represent the timing of emplacement of the lamproites. The ca. 2.0 Ga zircon grains correlate with the major thermal imprint associated with mafic magmatism and dyke emplacement in southern Bastar and the adjacent Dharwar Cratons. A few young zircon grains in the syenite and lamproites show a range of early to middle Neoproterozoic ages from 879 to 651 Ma corresponding to younger thermal event(s) as also represented by granitic veins cutting across these rocks and extensive silicification. Zircon Lu-Hf isotope data suggest magma derivation from a refertilized Paleo-Mesoarchean sub-continental lithospheric mantle, or OIB-type sources. The differences in Hf-isotope composition among the zircon grains from different age groups indicate that the mantle sources of the lamproite are heterogeneous at the regional scale. A combination of the features from geochemical and zircon Hf isotope data is consistent with asthenosphere-lithosphere interaction during the lamproite magma evolution. The timing of lamproite emplacement in central India correlates with the global 2.2 Ga record of LIPs. We link the origin of the related mantle plume to the recycling of subducted slabs associated with the prolonged subduction-accretion history prior to the Neoarchean cratonization, as well as the thermal blanket effect of the Earth’s oldest supercontinent. Pulsating plumes and continued rifting generated voluminous dyke swarms across the Bastar and Dharwar Cratons, forming part of a major global rifting and LIP event.
DS201802-0262
2018
Manu Prasanth, M.P.Santosh, M., Hari, K.R., He, X-F., Han, Y-S., Manu Prasanth, M.P.Oldest lamproites from Peninsular India track the onset of Paleoproterozoic plume induced rifting and the birth of Large Igneous Province.Gondwana Research, Vol. 55, pp. 1-20.Indialamproites

Abstract: Potassic and ultrapotassic magmatism from deep lithospheric sources in intra-cratonic settings can be the signal of subsequent voluminous mafic magmatism and the formation of Large Igneous Provinces (LIPs) triggered by mantle plumes. Here we report for the first time, precise zircon U-Pb age data from a suite of lamproites in the Bastar Craton of central India that mark the onset of Paleoproterozoic rifting and culminating in the formation of extensive mafic dyke swarms as the bar codes of one of the major LIP events during the Precambrian evolution of the Indian shield. The lamproites from the Nuapada field occur as dismembered dykes and are composed of phenocrysts and microphenocrysts of altered olivine together with microphenocrysts of phlogopite and magnetite within a groundmass of chlorite and calcite with accessory rutile, apatite and zircon. The rocks compositionally correspond to olivine phlogopite lamproite and phlogopite lamproite. Geochemical features of the lamproites correlate with their counterparts in Peninsular India and other similar suites elsewhere in the world related to rift settings, and also indicate OIB-like magma source. The associated syenite shows subduction-related features, possibly generated in a post-collisional setting. Magmatic zircon grains with high Th/U ratios in the syenite from the Nuapada lamproite form a coherent group with an upper intercept age of 2473 ± 8 Ma representing the timing of emplacement of the magma. Zircon grains in three lamproite samples yield four distinct age groups at ca. 2.4 Ga, 2.2 Ga, 2.0 Ga and 0.8 Ga. The 2.4 Ga group corresponds to xenocrysts entrained from the syenite whereas the 2.2 Ga group is considered to represent the timing of emplacement of the lamproites. The ca. 2.0 Ga zircon grains correlate with the major thermal imprint associated with mafic magmatism and dyke emplacement in southern Bastar and the adjacent Dharwar Cratons. A few young zircon grains in the syenite and lamproites show a range of early to middle Neoproterozoic ages from 879 to 651 Ma corresponding to younger thermal event(s) as also represented by granitic veins cutting across these rocks and extensive silicification. Zircon Lu-Hf isotope data suggest magma derivation from a refertilized Paleo-Mesoarchean sub-continental lithospheric mantle, or OIB-type sources. The differences in Hf-isotope composition among the zircon grains from different age groups indicate that the mantle sources of the lamproite are heterogeneous at the regional scale. A combination of the features from geochemical and zircon Hf isotope data is consistent with asthenosphere-lithosphere interaction during the lamproite magma evolution. The timing of lamproite emplacement in central India correlates with the global 2.2 Ga record of LIPs. We link the origin of the related mantle plume to the recycling of subducted slabs associated with the prolonged subduction-accretion history prior to the Neoarchean cratonization, as well as the thermal blanket effect of the Earth's oldest supercontinent. Pulsating plumes and continued rifting generated voluminous dyke swarms across the Bastar and Dharwar Cratons, forming part of a major global rifting and LIP event.
DS202003-0361
2020
Manu Prasanth, M.P.Santosh, M., Tsunogae, T., Yang, C-X., Han, Y-S., Hari, K.R., Manu Prasanth, M.P., Uthup, S.The Bastar craton, central India: a window to Archean - Paleoproterozoic crustal evolution.Gondwana Research, Vol. 79, pp. 157-184.Indiacraton

Abstract: The Bastar craton in central India, surrounded by cratonic blocks and Paleoproterozoic to Neoproterozoic orogenic belts, is a window to investigate the Archean-Paleoproterozoic crustal evolution and tectonic processes. Here we propose a new tectonic classification of the craton into the Western Bastar Craton (WBC), Eastern Bastar Craton (EBC), and the intervening Central Bastar Orogen (CBO). We present petrologic, geochemical and zircon U-Pb, REE and Lu-Hf data from a suite of rocks from the CBO and along the eastern margin of the WBC Including: (1) volcanic successions comprising meta-andesite and fine-grained amphibolite, representing arc-related volcanics along a convergent margin; (2) ferruginous sandstone, in association with rhyolite, representing a volcano-sedimentary succession, deposited in an active trench; and (3) metamorphosed mafic-ultramafic suite including gabbro, pyroxenite and dunite invaded by trondhjemite representing the section of sub-arc mantle and arc root adjacent to a long-lasting subduction system. Petrologic studies indicate that the mafic-ultramafic suite crystallized from an island arc tholeiitic parental magma in a suprasubduction zone environment. The chondrite-normalized and primitive mantle normalized diagrams of the mafic and ultramafic rocks suggest derivation from MORB magma. The mixed characters from N-MORB to E-MORB of the studied samples are consistent with subduction modification of a MORB related magma, involving partial melting of the metasomatized mantle wedge. Our zircon U-Pb age data suggest that the cratonic nuclei was constructed as early as Paleoarchean. We present evidence for active subduction and arc magmatism through Mesoarchean to Neoarchean and early Paleoproterozoic, with the trench remaining open until at least 2.3?Ga. Two major crust building events are recognized in the Bastar craton: during Mesoarchean (recycled Paleoarchean subduction-related as well as juvenile/depleted mantle components) and Neoarchean (accretion of juvenile oceanic crust, arc magmatism including granite batholiths and related porphyry mineralization). The final cratonization occurred during latest Paleoproterozoic, followed by collisional assembly of the craton and its incorporation within the Peninsular Indian mosaic during Mesoproterozoic. In the global supercontinent context, the craton preserves the history of Ur, the earliest supercontinent, followed by the Paleo-Mesoproterozoic Columbia, as well as minor thermal imprints of the Neoproterozoic Rodinia and associated Grenvillian orogeny.
DS1975-1080
1979
Manucharyants, A.O.Ivankin, P.F., Fel'dman, A.A., Manucharyants, A.O.Regional Localization Mechanisms for Kimberlites According To Geologic-geophysical Data.Tsnigri, No. 145, PP. 3-9.RussiaBlank
DS201312-0121
2013
Manuel, J.Campeny, M., Kamenetsky, V., Melgarejo, J.C., Mangas, J., Bambi, A., Manuel, J.CatAnd a carbonatitic lavas ( Angola): melt inclusion evidence.Goldschmidt 2013, AbstractAfrica, AngolaCarbonatite
DS201312-0122
2013
Manuel, J.Campeny, M., Kamenetsky, V., Melgarejo, J.C., Mangas, J., Bambi, A., Manuel, J.Sodium rich magmas parental to CatAnd a carbonatitic lavas ( Angola): melt inclusion evidence.Goldschmidt 2013, AbstractAfrica, AngolaCarbonatite
DS201412-0096
2014
Manuel, J.Campeny, M., Mangas, J., Melgarejo, J.C., Bambi, A., Alfonso, P., Gernon, T., Manuel, J.The Catanga extrusive carbonatites ( Kwanza Sul, Angola): an example of explosive carbonatitic volcanism.Bulletin of Volcanology, Vol. 76, pp. 818-Africa, AngolaCarbonatite
DS201509-0387
2015
Manuel, J.Campeny, M., Kamenetsky, V.S., Melgarejo, J.C., Mangas, J., Manuel, J., Alfonso, P., Kamenetsky, M.B., Bambi, A.C.J.M., Goncalves, A.O.Carbonatitic lavas in CatAnd a ( Kwanza Sul, Angola): mineralogical and geochemical constraints on the parental melt.Lithos, Vol. 232, pp. 1-11.Africa, AngolaCarbonatite

Abstract: A set of small volcanic edifices with tuff ring and maar morphologies occur in the Catanda area, which is the only locality with extrusive carbonatites reported in Angola. Four outcrops of carbonatite lavas have been identified in this region and considering the mineralogical, textural and compositional features, we classify them as: silicocarbonatites (1), calciocarbonatites (2) and secondary calciocarbonatites produced by the alteration of primary natrocarbonatites (3). Even with their differences, we interpret these lava types as having been a single carbonatite suite related to the same parental magma. We have also estimated the composition of the parental magma from a study of melt inclusions hosted in magnetite microphenocrysts from all of these lavas. Melt inclusions revealed the presence of 13 different alkali-rich phases (e.g., nyerereite, shortite, halite and sylvite) that argues for an alkaline composition of the Catanda parental melts. Mineralogical, textural, compositional and isotopic features of some Catanda lavas are also similar to those described in altered natrocarbonatite localities worldwide such as Tinderet or Kerimasi, leading to our conclusion that the formation of some Catanda calciocarbonatite lavas was related to the occurrence of natrocarbonatite volcanism in this area. On the other hand, silicocarbonatite lavas, which are enriched in periclase, present very different mineralogical, compositional and isotopic features in comparison to the rest of Catanda lavas. We conclude that its formation was probably related to the decarbonation of primary dolomite bearing carbonatites.
DS201801-0017
2017
Manuel, J.Giuliani, A., Campeny, M., Kamenetsky, V.S., Afonso, J.C., Maas, R., Melgarejo, J.C., Kohn, B.P., Matchen, E.L., Mangas, J., Goncalves, A.O., Manuel, J.Southwestern Africa on the burner: Pleistocene carbonatite volcanism linked to deep mantle upwelling in Angola.Geology, Vol. 45, 11, pp. 971=974.Africa, Angolacarbonatite - Catanda

Abstract: The origin of intraplate carbonatitic to alkaline volcanism in Africa is controversial. A tectonic control, i.e., decompression melting associated with far-field stress, is suggested by correlation with lithospheric sutures, repeated magmatic cycles in the same areas over several million years, synchronicity across the plate, and lack of clear age progression patterns. Conversely, a dominant role for mantle convection is supported by the coincidence of Cenozoic volcanism with regions of lithospheric uplift, positive free-air gravity anomalies, and slow seismic velocities. To improve constraints on the genesis of African volcanism, here we report the first radiometric and isotopic results for the Catanda complex, which hosts the only extrusive carbonatites in Angola. Apatite (U-Th-Sm)/He and phlogopite 40Ar/39Ar ages of Catanda aillikite lavas indicate eruption at ca. 500-800 ka, more than 100 m.y. after emplacement of abundant kimberlites and carbonatites in this region. The lavas share similar high-? (HIMU)-like Sr-Nd-Pb-Hf isotope compositions with other young mantle-derived volcanics from Africa (e.g., Northern Kenya Rift; Cameroon Line). The position of the Catanda complex in the Lucapa corridor, a long-lived extensional structure, suggests a possible tectonic control for the volcanism. The complex is also located on the Bié Dome, a broad region of fast Pleistocene uplift attributed to mantle upwelling. Seismic tomography models indicate convection of deep hot material beneath regions of active volcanism in Africa, including a large area encompassing Angola and northern Namibia. This is strong evidence that intraplate late Cenozoic volcanism, including the Catanda complex, resulted from the interplay between mantle convection and preexisting lithospheric heterogeneities.
DS1997-0645
1997
Manuel, L.Lajaunie, C., Courrioux, G., Manuel, L.Foliation fields and 3D cartography in geology: principles of a method based on potential interpolationMath. Geol, Vol. 29, No. 4, pp. 571-584GlobalGeostatistics, Kriging
DS200712-0534
2007
Manuel, S.Key, R.M., Bingen, B., Barton, E., Daudi, E.X.E., Manuel, S., Moniz, A.Kimberlites in a Karoo graben of northern Mozambique: tectonic setting, mineralogy and RbSr geochronology.South African Journal of Geology, Vol. 110, 1, pp. 111-124.Africa, MozambiqueGeochronology
DS201412-0546
2013
Manuella, F.C.Manuella, F.C.Can nanodiamonds grow in serpentinite-hosted hydrothermal systems? A theoretical modelling study.Mineralogical Magazine, Vol. 77, pp. 3163-3174.TechnologyNanodiamonds
DS1900-0236
1904
Manufacture JewellerManufacture JewellerAfter Precious Stones in KentuckyManufacturer Jeweller, Vol. 34, Feb. 4TH. P. 125.United States, Kentucky, AppalachiaDiamond Occurrence
DS1900-0099
1902
Manufacture JewellersManufacture JewellersDiamond Found in IndianaManufacturer Jewellers, Vol. 30, MAY 29TH. P. 556.United States, Indiana, Great LakesDiamond Occurrence
DS1900-0287
1905
Manufacturer JewellerManufacturer JewellerAfter Diamonds in MexicoManufacturer Jeweller, Vol. 37, Nov. 23RD. P. 632.MexicoDiamond Occurrence
DS1900-0301
1905
Manufacturer JewellerManufacturer JewellerDiamonds Near PlacervilleManufacturer Jeweller, Vol. 37, Oct. 12TH. P. 358.United States, California, West CoastDiamond Occurrence, Diamonds Notable
DS1900-0304
1905
Manufacturer JewellerManufacturer JewellerTo Hunt for Diamonds in KentuckyManufacturer Jeweller, Vol. 37, AUG. 31ST. PP. 204-206.United States, Kentucky, AppalachiaDiamond Occurrence, Diamonds Notable
DS1900-0389
1906
Manufacturer JewellerManufacturer JewellerLooking for Diamonds in KentuckyManufacturer Jeweller., Vol. 38, APRIL 7TH. P. 472.United States, Kentucky, AppalachiaDiamond Occurrence, Diamonds Notable
DS1900-0390
1906
Manufacturer JewellerManufacturer JewellerThose Kentucky Diamond Mines (1906)Manufacturer Jeweller., Vol. 39, Dec. 17TH. P. 811.United States, Kentucky, AppalachiaDiamond Occurrence, Diamonds Notable
DS1900-0517
1907
Manufacturer JewellerManufacturer JewellerAn American Diamond MineManufacturer Jeweller., Vol. 41, SEPT. 19TH. P. 434.United States, Gulf Coast, Arkansas, PennsylvaniaDiamond Occurrence
DS1900-0523
1907
Manufacturer JewellerManufacturer JewellerThose Kentucky Diamond Mines (1907)Manufacturer Jeweller., Vol. 40, MARCH 28TH. P. 484.United States, Kentucky, AppalachiaDiamond Occurrence
DS1900-0524
1907
Manufacturer JewellerManufacturer JewellerThe Kentucky Diamond ProspectManufacturer Jeweller., Vol. 41, Oct. 24TH. P. 640.United States, Kentucky, AppalachiaDiamond Occurrence
DS1900-0526
1907
Manufacturer JewellerManufacturer JewellerDiamonds of Little Value Found in MichiganManufacturer Jeweller, Vol. 41, SEPT. 5TH. P. 370.United States, Michigan, Great LakesDiamond Occurrence
DS1900-0608
1908
Manufacturer JewellerManufacturer JewellerDiamonds Found in CanadaManufacturer Jeweller, Vol. 42, MAY 14TH. P. 840.Canada, QuebecDiamond Occurrence
DS1900-0610
1908
Manufacturer JewellerManufacturer JewellerDiamonds in Shantung, China, 1908Manufacturer Jeweller, Vol. 42, Jan. 2ND. P. 8.China, ShandongPolitics, Diamond Production
DS1900-0628
1908
Manufacturer JewellerManufacturer JewellerThe California Diamond MineManufacturer Jeweller., Vol. 42, MARCH 26TH. P. 560.United States, California, West CoastDiamond Occurrence
DS1900-0633
1908
Manufacturer JewellerManufacturer JewellerBlue Ground Struck at OrovilleManufacturer Jeweller., Vol. 42, MAY 14TH. P. 840.United States, California, West Coast, MontanaDiamond Occurrence
DS1900-0637
1908
Manufacturer JewellerManufacturer JewellerActivity in Arkansas Diamond FieldsManufacturer Jeweller., Vol. 43, Dec. 17TH. P. 1076.United States, Gulf Coast, Arkansas, PennsylvaniaEconomics
DS1900-0736
1909
Manufacturer JewellerManufacturer JewellerDiamonds from CaliforniaManufacturer Jeweller, Vol. 44United States, California, West Coast, MontanaDiamond Occurrence
DS1860-0782
1893
Manufactures JewellersManufactures JewellersSalting the Idaho MinesManufacturers Jewellers, Vol. 12, Feb. 1ST. P. 173.United States, Idaho, Rocky MountainsLegal
DS1860-0832
1894
Manufactures JewellersManufactures JewellersDiamonds Near Cornishville KentuckyManufacturer Jewellers, Oct. 5TH.United States, Kentucky, AppalachiaDiamond Occurrence
DS202203-0356
2022
Manuilova, E.A.Manuilova, E.A.The relationships of the dislocations of the basement and sedimentary cover with the newest structural plan of the west Siberian plate.Moscow University Bulletin, Vol. 76, 5, pp. 425-500.Russiacraton

Abstract: Comparison of the newest structural plan of the West Siberian Plate with the dislocations of the basement and sedimentary cover allowed us to rank the latest plicative and disjunctive structures by the degree of inheritance. As a result, the inherited, reversed, and newly formed plicative structural forms were distinguished. It is shown that the orientation of ancient structures differs from the modern ones and the inheritance occurs only fragmentarily. The inherited and newly formed faults were distinguished by comparison of the newest faults with the ancient ones. The discovered inherited newest structures may be considered as promising areas for prospecting for hydrocarbon deposits.
DS2002-0428
2002
Manukhin, A.V.Elyutin, A.V., Ermolaev, A.A., Laptev, A.I., Manukhin, A.V.Effect of boron on the thermal stability of polycrystalline carbonado diamondsDoklady Physics, (language not known), Vol. 47, 9, pp. 651-3.GlobalCarbonados
DS2000-0613
2000
Manutchehr-Danai, M.Manutchehr-Danai, M.Dictionary of gems and gemology. #2Springer Publishing, 576p. approx. $ 200.00 United States ISBN 3-540-67482-9GlobalBook - reference, Dictionary - gems, gemology
DS200512-0684
2005
Manutchehr-Danai, M.Manutchehr-Danai, M.Dictionary of gems and gemology.Springer, Revised edition 880p. $ 259. ISBN 3-540-23970-7Book - mineralogy, gems
DS200812-0713
2008
Manutchehr-Danai, M.Manutchehr-Danai, M.Dictionary of Gems and Gemology.Springer, Price $ 599.00 ISBN 978-3-540-72795-8TechnologyBook - encyclopedia of gemology, mineralogy
DS1997-0607
1997
Manutsoglu, E.Kley, J., Muller, J., Manutsoglu, E.Pre-Andean and Andean age deformation in the Eastern Cordillera of SouthernBoliviaJournal of South American Earth Sciences, Vol. 10, No. 1, pp, 1-20BoliviaMetamorphism, Deformation
DS2003-0874
2003
Manya, S.Manya, S., Makabo, M.A.H.Dating basaltic volcanism in the Neoarchean Sukumaland greenstone belt of thePrecambrian Research, Vol. 121, 1-2. Feb. 28, pp. 35-45.TanzaniaCraton - geochronology
DS200612-0861
2006
Manya, S.Manya, S., Kobayashi, K., Maboko, M.A., Nakamura, E.Ion microprobe zircon U Pb dating of the late Archean metavolcanics and associated granites of the Musoma Mara greenstone belt, northeast Tanzania: implicationsJournal of African Earth Sciences, Vol. 45, 3, pp. 355-366.Africa, TanzaniaCraton, geochronology, not specific to diamonds
DS201112-0642
2011
Manya, S.Manya, S.Nd-isotopic mapping of the Archean Proterozoic boundary in southwestern Tanzania: implication for the size of the Archean Tanzanian craton.Gondwana Research, Vol. 20, 2-3, pp. 325-334.Africa, TanzaniaCraton
DS201212-0092
2012
Manya, S.Brown, R.J., Manya, S., Buisman, I., Fontana, G., Field, M., MacNiocaill, C., Sparks, R.S.J., Stuart, F.M.Eruption of kimberlite magmas: physical volcanology, geomrphology and age of the youngest kimberlitic volcanoes known on Earth ( the Upper Pleistocene-Holocene Igwisi Hills, volcanoes, Tanzania.Bulletin of Volcanology, Vol. 74, 7, pp. 1621-1643.Africa, TanzaniaIgwisi Hills
DS201212-0093
2012
Manya, S.Brown, R.J., Manya, S., Buisman, I., Sparks, R.S.J., Field, M., Stuart, F.M., Fontana, G.Physical volcanology, geomorphology, and cosmogenic 3HE dating of the youngest kimberlite volcanoes on Earth ( The Holocene Igwisi Hills, Volcanoes, Tanzania.10th. International Kimberlite Conference Feb. 6-11, Bangalore India, AbstractAfrica, TanzaniaIgwisi Hills - geochronology
DS201212-0095
2012
Manya, S.Buisman, I., Sparks, R.S.J., Walter, M.J., Brown, R.J., Manya, S., Kavanagh, J.Olivine chemistry of exceptionally young ( Holocene) kimberlite of the Igwisi Hills volcano, Tanzania.10th. International Kimberlite Conference Held Bangalore India Feb. 6-11, Poster abstractAfrica, TanzaniaDeposit - Igwisi
DS201412-0079
2014
Manya, S.Buisman, I., Sparks, R.S.J., Brown, R., Manya, S.Microanalysis of olivine chemistry of exceptionally young kimberlite of the Igwisi Hills, volcano, Tanzania.Volcanic and Magmatic Studies Group meeting, Poster Held Jan. 6-8. See minsoc websiteAfrica, TanzaniaIgwisi
DS202007-1144
2020
Manya, S.Haddock, D., Manya, S., Brown, R.J., Jones, T.J., Wadsworth, F.B., Dobson, K.J., Gernon, T.M.Syn-eruptive agglutination of kimberlite volcanic ash. PyroclastsVolcanica, Vol. 3, 1, pp. 169-182. PdfAfrica, Tanzaniadeposit - Igwisi Hills

Abstract: Pyroclastic deposits of the Holocene Igwisi Hills kimberlite volcanoes, Tanzania, preserve unequivocal evidence for rapid, syn-eruptive agglutination. The unusual pyroclasts are composed of ash-sized particles agglutinated to each other by thin necks. The textures suggest the magma was disrupted into droplets during ascent. Collisions between particles occurred within a volcanic plume and on deposition within the conduit to form a weakly agglutinated, porous pyroclastic deposit. Theoretical considerations indicate that agglutination occurred over short timescales. Agglutinated clasts were entrained into weak volcanic plumes and deposited around the craters. Our results support the notion that agglutination can occur during kimberlite eruptions, and that some coherent, dense rocks in ancient kimberlite pipes interpreted as intrusive rocks could instead represent agglutinated pyroclastic rocks. Differentiating between agglutinated pyroclastic rocks and effusive or intrusive rocks in kimberlite pipes is important because of the potential effects that pyroclastic processes might have on diamond concentrations in deposits.
DS202011-2040
2020
Manya, S.Haddock, D., Manya, S., Brown, R.J., Jones, T.J., Wadsworth, F.B., Dobson, K.J., Gernon, T.M.Syn-eruptive agglutination of kimberlite volcanic ash.Volcanica, 15p. PdfAfrica, Tanzaniadeposit - Igwisi Hills kimberlite

Abstract: Pyroclastic deposits of the Holocene Igwisi Hills kimberlite volcanoes, Tanzania, preserve unequivocal evidence for rapid, syn-eruptive agglutination. The unusual pyroclasts are composed of ash-sized particles agglutinated to each other by thin necks. The textures suggest the magma was disrupted into droplets during ascent. Collisions between particles occurred within a volcanic plume and on deposition within the conduit to form a weakly agglutinated, porous pyroclastic deposit. Theoretical considerations indicate that agglutination occurred over short timescales. Agglutinated clasts were entrained into weak volcanic plumes and deposited around the craters. Our results support the notion that agglutination can occur during kimberlite eruptions, and that some coherent, dense rocks in ancient kimberlite pipes interpreted as intrusive rocks could instead represent agglutinated pyroclastic rocks. Differentiating between agglutinated pyroclastic rocks and effusive or intrusive rocks in kimberlite pipes is important because of the potential effects that pyroclastic processes might have on diamond concentrations in deposits.
DS201212-0495
2012
Manyumbu, A.Moss, S., Webb, K., Hetman, C., Manyumbu, A., Muchechetere, C.Geology of the K1 and K2 kimberlite pipes at Murowa, Zimbabwe.10th. International Kimberlite Conference Held Bangalore India Feb. 6-11, Poster abstractAfrica, ZimbabweDeposit - Murowa
DS201412-0598
2013
Manyumbu, A.Moss, S., Webb, K., Hetman, C., Manyumbu, A.Geology of the K1 and K2 kimberlite pipes at Murowa, Zimbabwe.Proceedings of the 10th. International Kimberlite Conference, Vol. 2, pp. 35-41.Africa, ZimbabweDeposit - Murowa
DS201012-0765
2010
MaoSu, B-X., Zhang, H-F., Sakyi, P.A., Yang, Y-H., Ying, J-F., Tang, Y-J., Qin, K-Z., Xiao, Y., Zhao, Mao, MaThe origin of spongy texture in minerals of mantle xenoliths from the western Qinling, central China.Contributions to Mineralogy and Petrology, in press available, 18p.ChinaXenoliths
DS201812-2848
2018
MaoMao, W, Zhong, S.Slab stagnation in the transition zone is explained by a thin, weak layer and is transient on timescales of tens or millions of years, according to a global mantle convection model that includes phase changes and plate motion.Nature Geoscience, doi:10.038/s41561-018-0225-2 (pp. 876-881.)Mantleconvection

Abstract: The linear structures of seismically fast anomalies, often interpreted as subducted slabs, in the southern Asia and circum-Pacific lower mantle provided strong evidence for the whole mantle convection model. However, recent seismic studies have consistently shown that subducted slabs are deflected horizontally for large distances in mantle transition zone in the western Pacific and other subduction zones, suggesting that the slabs meet significant resistance to their descending motion and become stagnant in the transition zone. This poses challenges to the whole mantle convection model and also brings the origin of stagnant slabs into question. Here, using a global mantle convection model with realistic spine-post-spinel phase change (?2 MPa K?¹ Clapeyron slope) and plate motion history, we demonstrate that the observed stagnant slabs in the transition zone and other slab structures in the lower mantle can be explained by the presence of a thin, weak layer at the phase change boundary that was suggested by mineral physics and geoid modelling studies. Our study also shows that the stagnant slabs mostly result from subduction in the past 20-30 million years, confirming the transient nature of slab stagnation and phase change dynamics on timescales of tens of millions of years from previous studies.
DS2003-0875
2003
Mao, et al.Mao, et al.Halfway to diamond... carbon forms sp3 bond in a three dimensional structureScience, No. 5644, Oct. 17, p. 425.GlobalDiamond- morphology, crystallography
DS200412-1221
2003
Mao, et al.Mao, et al.Halfway to diamond... carbon forms sp3 bond in a three dimensional structure.Science, No. 5644, Oct. 17, p. 425.TechnologyDiamond- morphology, crystallography
DS2000-1032
2000
Mao, H.Xu, J., Mao, H.Moissanite: a window for high pressure experimentsScience, Vol. 290, No. 5492, Oct. 27, pp. 783-4.GlobalMoissanite
DS2003-0819
2003
Mao, H.Lin, J.F., Heinz, D.L., Mao, H., Hemley, R.J., Devine, J.M., Shen, G.Stability of magnesiowurstite in Earth's lower mantleProceedings of the National Academy of Sciences, USA, Vol. 100, 8, pp. 4405-8.MantlePetrology
DS200412-1138
2003
Mao, H.Lin, J.F., Heinz, D.L., Mao, H., Hemley, R.J., Devine, J.M., Shen, G.Stability of magnesiowurstite in Earth's lower mantle.Proceedings of National Academy of Science USA, Vol. 100, 8, pp. 4405-8.MantlePetrology
DS200512-0638
2005
Mao, H.Lin, J.F., Struzhkin, V.V., Jacobsen, S.D., Hu, M.Y., Chow, P., Kung, J., Liu, H., Mao, H., Hemley, R.J.Spin transition of iron in magnesiowustite in the Earth's lower mantle.Nature, No. 7049, July 21, pp. 377-380.MantleMineralogy
DS200812-0642
2008
Mao, H.Lee, S.K., Lin, J.F., Cai, Y.Q., Hiraoka, N., Eng, P.J., Okuchi, T., Mao, H., Meng, Y., Hu, M.Y.,Chow, P.X ray Raman scattering study of MgSi)3 glass at high pressure: implication for triclustered MgSiO3 melt in Earth's mantle.Proceedings of National Academy of Sciences USA, Vol. 105, 23, June 10, pp. 7925-7929.MantleMelting
DS201312-0539
2013
Mao, H.Liang, Q., Meng, Y., Yan, C., Krasnicki, S., Lai, J., Hemawan, K., Shu,H., Popov, D., Yu,T., Yang, W., Mao, H., Hemley, R.Developments in synthesis, characterization, and application of large high-quality CVD single crystal diamond.Journal of Superhard Materials, Vol. 35, 4, pp. 195-213.TechnologyDiamond synthetics
DS1986-0881
1986
Mao, H.K.Xu, J.A., Mao, H.K., Bell, P.M.high pressure ruby and diamond fluoresence: observations at 0.21 and 0.55terapascalScience, Vol. 232, June 13, pp. 1404-1406. also reviewed in EOSGlobalDiamond, Crystallography
DS1991-1047
1991
Mao, H.K.Mao, H.K., Hemley, R.J.Optical transitions in diamond at ultrahigh pressuresNature, Vol. 351, No. 6329, June 27, pp. 721-724GlobalDiamond morphology, Spectroscopy
DS1992-1478
1992
Mao, H.K.Stixrude, L., Hemley, R.J., Fei, Y., Mao, H.K.Thermoeleasticity of silicate perovskite and magnesiowustite and stratification of the earth's mantleScience, Vol. 257, August 21, pp. 1099-1101MantleStratification, Perovskite
DS1995-0957
1995
Mao, H.K.Kingma, K.J., Cohen, R.E., Hemley, R.J., Mao, H.K.Transformation of stishovite to a denser phase at lower mantle pressuresNature, Vol. 374, No. 6519, March 16, p. 243-245.MantleCoesite association
DS1998-0608
1998
Mao, H.K.Hemley, R.J., Mao, H.K., Cohen, R.E.high pressure electronic and magnetic propertiesReviews in Mineralogy, Vol. 37, pp. 591-638.MantleMineralogy, Petrology - experimental
DS1998-1335
1998
Mao, H.K.Shieh, S.R., Mao, H.K., Ming, L.C.Decomposition of phase D in the lower mantle and the fate of dense hydrous silicates in subducting slabs.Earth and Planetary Science Letters, Vol. 159, No. 1-2, June 15, pp. 13-24.MantleSubduction
DS2001-0468
2001
Mao, H.K.Hemley, R.J., Mao, H.K.In situ studies of iron under pressure: new windows on the Earth's coreInternational Geology Review, Vol. 43, No. 1, Jan. pp. 1-30.MantleCore - mineralogy
DS2001-0683
2001
Mao, H.K.Li, J., Fei, Y., Mao, H.K., Hirose, K., Shieh, S.R.Sulfur in the Earth's coreEarth and Planetary Science Letters, Vol. 193, No. 3-4, pp.509-14.MantleSulphur, Geochemistry
DS2002-0704
2002
Mao, H.K.Hemley, R.J., Mao, H.K.New windows on earth and planetary interiorsMineralogical magazine, Vol. 66,5, pp. 791-811.GlobalPetrology - mineralogy - not specific to diamonds
DS2002-0705
2002
Mao, H.K.Hemley, R.J., Mao, H.K.New windows on earth and planetary interiorsMineralogical Magazine, Vol.66, 6, pp. 791-812.MantleCore
DS1986-0522
1986
Mao, H-K.Mao, H-K., Xu J., Bell, P.M.Geophysical experiments: Ruby and diamond fluorescence measurements at 0.2-0. 5 terapascals ( 2-5 megabars)Eos, Vol. 67, No. 16, April 22, p. 368. (abstract.)GlobalDiamond morphology
DS1998-0936
1998
Mao, H-K.Mao, H-K., Hemley, R.J.New windows on the Earth's deep interiorReviews in Mineralogy, Vol. 37, pp. 1-32.GlobalLithosphere, Geophysics - gravity
DS2003-0937
2003
Mao, H-K.Meng, Y., Newville, M., Sutton, S., Rakovan, J., Mao, H-K.Fe and Ni impurities in synthetic diamondAmerican Mineralogist, Vol. 88, 10, Oct. pp. 1555-69.GlobalDiamond - synthesis
DS200412-1297
2003
Mao, H-K.Meng, Y., Newville, M., Sutton, S., Rakovan, J., Mao, H-K.Fe and Ni impurities in synthetic diamond.American Mineralogist, Vol. 88, 10, Oct. pp. 1555-69.TechnologyDiamond - synthesis
DS200412-2098
2004
Mao, H-K.Wenk, H.R., Lonardeli, I., Pehl, J., Devine, J., Prakapenka, V., Shen, G., Mao, H-K.In situ observation of texture development in olivine, ringwoodite, magnesiowustite and silicate perovskite at high pressure.Earth and Planetary Science Letters, Vol. 226, 3-4, Oct. 15, pp.507-519.Mantle, United States, New MexicoMagnesium silicates, San Carlos
DS200612-0862
2006
Mao, H-K.Mao, H-K., Mao, W.L.Core mantle interaction - the formation, elasticity, rheology and dynamics of iron rich silicate in core mantle boundary layer.International Mineralogical Association 19th. General Meeting, held Kobe, Japan July 23-28 2006, Abstract p. 126.MantleGeophysics - seismics, D layer
DS200612-0863
2006
Mao, H-K.Mao, W.L., Mao, H-K., Sturhahn, W., Zhao, J., Prakapenka, V.B., Meng, Y., Shu, J., Hemley, R.J.Iron rich post perovskite and the origin of ultralow-velocity zones.Science, Vol. 312, April 28, pp. 564-565.MantleGeophysics - seismics, silicate
DS201412-1024
2014
Mao, H-K.Zhang, L., Meng, Y., Yang, W.,Wang, L., Mao, W.L., Zeng, Q-S., Jeong, J.S., Wagner, A.J., Mkhoyan, K.A., Liu, W., Xu, R., Mao, H-K.Disproportionation of (Mg,Fe) SiO3 perovskite in Earth's deep lower mantle.Science, Vol. 344, no. 6186, pp. 877-882.MantlePerovskite
DS201910-2255
2019
Mao, H-k.Du, Z., Deng, J., Miyazaki, Y., Mao, H-k., Karki, B.B., Lee, K.K.M.Fate of hydrous Fe-silicate melt in Earth's deep mantle.Geophysical Research Letters, Vol. 46, doi.org/ 10.1029/ 2019GL083633Mantlemelting

Abstract: Planetary?scale melting is ubiquitous after energetic impacts early in Earth's history. Therefore, determining key melt properties, such as density, is of great significance to better understand Earth's formation and subsequent evolution. In this study, we performed state?of?art first?principles molecular dynamics simulations to examine the density of deep mantle melts, namely, hydrous Fe?rich silicate melts. We find that such hydrous melts can be gravitationally stable near Earth's core?mantle boundary given their likely high iron content. This has great implications for Earth's thermochemical evolution, as well as Earth's volatile cycle.
DS201911-2520
2019
Mao, H-K.Du, Z., Deng, J., Miyazaki, Y., Mao, H-K., Karki, B.B., Lee, K.K.M.Fate of hydrous Fe-rich silicate melt in Earth's deep mantle.Geophysical Research Letters, Vol. 46, 16, pp. 9466-9473.Mantlewater

Abstract: Planetary-scale melting is ubiquitous after energetic impacts early in Earth's history. Therefore, determining key melt properties, such as density, is of great significance to better understand Earth's formation and subsequent evolution. In this study, we performed state-of-art first-principles molecular dynamics simulations to examine the density of deep mantle melts, namely, hydrous Fe-rich silicate melts. We find that such hydrous melts can be gravitationally stable near Earth's core-mantle boundary given their likely high iron content. This has great implications for Earth's thermochemical evolution, as well as Earth's volatile cycle.
DS201912-2799
2019
Mao, H-K.Liu, J., Hu, Q., Bi, W., Yang, L., Xiao, Y., Chow, P., Meng, Y., Prakapenka, V.B., Mao, H-K., Mao, W.L.Altered chemistry of oxygen and iron under deep Earth conditionsNature Communications, 8p. PdfMantlegeochemistry

Abstract: A drastically altered chemistry was recently discovered in the Fe-O-H system under deep Earth conditions, involving the formation of iron superoxide (FeO2Hx with x?=?0 to 1), but the puzzling crystal chemistry of this system at high pressures is largely unknown. Here we present evidence that despite the high O/Fe ratio in FeO2Hx, iron remains in the ferrous, spin-paired and non-magnetic state at 60-133?GPa, while the presence of hydrogen has minimal effects on the valence of iron. The reduced iron is accompanied by oxidized oxygen due to oxygen-oxygen interactions. The valence of oxygen is not -2 as in all other major mantle minerals, instead it varies around -1. This result indicates that like iron, oxygen may have multiple valence states in our planet’s interior. Our study suggests a possible change in the chemical paradigm of how oxygen, iron, and hydrogen behave under deep Earth conditions.
DS202202-0205
2022
Mao, H-K.Lin, Y., van Westrenen, W., Mao, H-K.Oxygen controls on magmatism rocky exoplanets. Proceedings of the National Academy of Sciences, Vol. 78, 10.1073/pnas2110427118 6p. PdfCosmosmelting

Abstract: Refractory oxygen bound to cations is a key component of the interior of rocky exoplanets. Its abundance controls planetary properties including metallic core fraction, core composition, and mantle and crust mineralogy. Interior oxygen abundance, quantified with the oxygen fugacity (fO2), also determines the speciation of volatile species during planetary outgassing, affecting the composition of the atmosphere. Although melting drives planetary differentiation into core, mantle, crust, and atmosphere, the effect of fO2 on rock melting has not been studied directly to date, with prior efforts focusing on fO2-induced changes in the valence ratio of transition metals (particularly iron) in minerals and magma. Here, melting experiments were performed using a synthetic iron-free basalt at oxygen levels representing reducing (log fO2 = ?11.5 and ?7) and oxidizing (log fO2 = ?0.7) interior conditions observed in our solar system. Results show that the liquidus of iron-free basalt at a pressure of 1 atm is lowered by 105 ± 10?°C over an 11 log fO2 units increase in oxygen abundance. This effect is comparable in size to the well-known enhanced melting of rocks by the addition of H2O or CO2. This implies that refractory oxygen abundance can directly control exoplanetary differentiation dynamics by affecting the conditions under which magmatism occurs, even in the absence of iron or volatiles. Exoplanets with a high refractory oxygen abundance exhibit more extensive and longer duration magmatic activity, leading to more efficient and more massive volcanic outgassing of more oxidized gas species than comparable exoplanets with a lower rock fO2.
DS202203-0350
2022
Mao, H-K.He, Y., Sun, S., Kim, D.Y., Jang, B.G., Li, H., Mao, H-K.Superionic iron alloys and their seismic velocities in Earth's inner core.Nature, Vol. 602, pp. 258-276. 18p.Mantlecore

Abstract: Earth’s inner core (IC) is less dense than pure iron, indicating the existence of light elements within it1. Silicon, sulfur, carbon, oxygen and hydrogen have been suggested to be the candidates2,3, and the properties of iron-light-element alloys have been studied to constrain the IC composition4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19. Light elements have a substantial influence on the seismic velocities4,5,6,7,8,9,10,11,12,13, the melting temperatures14,15,16,17 and the thermal conductivities18,19 of iron alloys. However, the state of the light elements in the IC is rarely considered. Here, using ab initio molecular dynamics simulations, we find that hydrogen, oxygen and carbon in hexagonal close-packed iron transform to a superionic state under the IC conditions, showing high diffusion coefficients like a liquid. This suggests that the IC can be in a superionic state rather than a normal solid state. The liquid-like light elements lead to a substantial reduction in the seismic velocities, which approach the seismological observations of the IC20,21. The substantial decrease in shear-wave velocity provides an explanation for the soft IC21. In addition, the light-element convection has a potential influence on the IC seismological structure and magnetic field.
DS202205-0686
2021
Mao, H-K.Hu, Q., Mao, H-K.Role of hydrogen and proton transportation in Earth's deep mantle.Matter Radiation Extremes, Vol. 6, 068101 2p. PdfMantlehydrogen

Abstract: Hydrogen (H) is the most abundant element in the known universe, and on the Earth’s surface it bonds with oxygen to form water, which is a distinguishing feature of this planet. In the Earth’s deep mantle, H is stored hydroxyl (OH?) in hydrous or nominally anhydrous minerals. Despite its ubiquity on the surface, the abundance of H in the Earth’s deep interior is uncertain. Estimates of the total H budget in the Earth’s interior have ranged from less than one hydrosphere, which assumes an H-depleted interior, to hundreds of hydrospheres, which assumes that H is siderophile (iron-loving) in the core. This discrepancy raises the questions of how H is stored and transported in the Earth’s deep interior, the answers to which will constrain its behavior in the deep lower mantle, which is defined as the layer between 1700 km depth and the core-mantle boundary. Hydrogen is the lightest element and exhibits superior mobility under high pressure-temperature (P-T) conditions. Hydrogen, once it has lost its only electron, is electronically equivalent to the proton and can substitute at cation sites in minerals, which in turn enhances their ionic conductivity through the Grotthuss mechanism, or “hydrogen hopping,” in which a proton or proton defect diffuses through the crystal lattice by the formation and concomitant breaking of hydroxyl bonding. Grotthuss-type diffusion is dominant for H-incorporated silicate in the asthenosphere, particularly in regions under relatively high-temperature and low-pressure conditions.1 With increasing depth, H may be liberated from hydroxyl bonding and diffuse freely in the host crystalline lattice, entering an exotic superionic phase.2,3 The concept of a superionic phase is borrowed from the electric battery industry, and the existence of such a phase in ice is widely recognized. The recent discovery of superionic ice-silica in the interiors of giant planets suggests that superionic phases may be common in planetary deep interiors.4 The electrical and seismic features of superionic phases are of great importance, and they have been the subjects of recent studies.2,4 However, what is more challenging is the nature of H in these exotic “semi-fluid” like phases. Will superionicity induce distinct behavior in the distribution of H in major mineral phases? What is the role of proton transportation in the convection of materials? Will it have a large-scale impact? We take superionic FeOOH as an illustrative example, since this is one of the few superionic phases that have been experimentally confirmed. From a survey of data in the literature, we have found that the pressure and amount of escaped H (nH) are correlated (Fig. 1). Here, we define nH as the fraction of H that has escaped from FeOOH, with nH = 0 for fully hydrous FeOOH, and nH = 1 for complete H depletion. Escape of H is inhibited by increasing pressure, and nH converges to a minimum value of ?0.2 at the pressure of the core-mantle boundary (Fig. 1), which is consistent with a recent kinetic experiment involving the heating of FeOOH and the prediction of FeOOH0.75 as a stable stoichiometry.5 The regression of P-nH indicates that cross-boundary diffusion is more intense at relatively low pressures.
DS200612-1595
2006
Mao, J.Zhang, Z., Mahoney, J., Mao,J., Wang, F.Geochemistry of picritic and associated basalt flows of the western Emeishan flood basalt province, China.Journal of Petrology, Vol. 47, 10, pp. 1997-2019.ChinaPicrite
DS201512-1939
2015
Mao, M.Mao, M., Simandl, G.J., Spence, J., Marshall, D.Fluorite trace-element chemistry and its potential as an indicator mineral: evaluation of LA-ICP-MS method.Symposium on critical and strategic materials, British Columbia Geological Survey Paper 2015-3, held Nov. 13-14, pp. 251-264.TechnologyRare earths

Abstract: Fluorite (CaF2) belongs to the isometric system, with a cubic, face-centred lattice. Fluorite commonly forms cubes or octahedrons, less commonly dodecahedrons and, rarely, tetrahexahedrons, trapezohedrons, trisoctahedrons, hexoctahedrons, and botyroidal forms. Fluorite is transparent to translucent, and has vitreous luster. It occurs in a variety of colours including purple, green, blue, or yellow, however it can also be colourless, and can exhibit colour zoning, (Staebler et al., 2006). Fluorite from many localities is fl uorescent (Verbeek, 2006). Fluorite density varies from 3.0-3.6 g/cm3, depending to a large extent on inclusions and impurities in the crystal lattice (Staebler et al., 2006), and its hardness is 4 on Mohs scale (Berry et al., 1983). Many single fl uorite crystals display sector zoning, refl ecting preferential substitution and incorporation of trace elements along successive crystal surfaces (Bosce and Rakovan, 2001). The Ca2+ ion in the fl uorite crystal structure can be substituted by Li+, Na+, K+, Mg2+, Mn2+, Fe2+,3+, Zn2+, Sr2+, Y3+, Zr4+, Ba2+, lanthanides ions, Pb2+, Th4+, and U4+ ions (Bailey et al., 1974; Bill and Calas, 1978, Gagnon et al., 2003; Schwinn and Markl, 2005; Xu et al., 2012; Deng et al., 2014). Concentrations of these impurities do not exceed 1% (Deer, 1965) except in yttrofl uorite (Ca,Y)F2-2.33 and cerfl uorite (Ca,Ce)F2-2.33 (Sverdrup, 1968). Fluorite occurs in a variety of rocks, as an accessory and as a gangue mineral in many metalliferous deposits and, in exceptional cases, as the main ore constituent of economic deposits (Simandl, 2009). Good examples of fl uorite mines are Las Cuevas, Encantada-Buenavista (Mexico); St. Lawrence pluton-related veins and the Rock Candy Mine (Canada); El Hamman veins (Morocco) and LeBurc Montroc -Le Moulinal and Trebas deposits (France) as documented by Ruiz et al. (1980), Grogan and Montgomery (1975), González-Partida et al. (2003), Munoz et al. (2005), and Fulton III and Miller (2006). Fluorite also commonly occurs adjacent to or within carbonatites and alkaline complexes (Kogut et al., 1998; Hagni,1999; Alvin et al., 2004; Xu et al., 2004; Salvi and Williams-Jones, 2006); Mississippi Valley-type (MVT) Pb- Zn-F-Ba deposits; F-Ba-(Pb-Zn) veins (Grogan and Bradbury, 1967 and 1968; Baxter et al., 1973; Kesler et al., 1989; Cardellach et al., 2002; Levresse et al., 2006); hydrothermal Fe (±Au, ±Cu) and rare earth element (REE) deposits (Borrok et al., 1998; Andrade et al., 1999; Fourie, 2000); precious metal concentrations (Hill et al., 2000); fl uorite/metal-bearing skarns (Lu et al., 2003); Sn-polymetallic greissen-type deposits (Bettencourt et al., 2005); and zeolitic rocks and uranium deposits (Sheppard and Mumpton, 1984; Cunningham et al., 1998; Min et al., 2005). Ore deposit studies that document the trace element distribution in fl uorite are provided by Möller et al. (1976), Bau et al. (2003), Gagnon et al. (2003), Schwinn and Markl (2005), and Deng et al. (2014). The benchmark paper by Möller et al. (1976) identifi ed variations in the chemical composition of fl uorites according their origin (sedimentary, hydrothermal, or pegmatitic). Recently, Makin et al. (2014) compiled trace-element compositions of fl uorite from MVT, fl uorite-barite veins, peralkaline-related, and carbonatite-related deposits. They showed that fl uorite from MVT and carbonatite deposits can be distinguished through trace element concentrations, and that the REE concentration of fl uorite from veins is largely independent of the composition of the host rock. Based on the physical and chemical properties of fl uorite, its association with a variety of deposit types, and previous studies, it is possible that fl uorite can be used as a proximal indicator mineral to explore for a variety of deposit types. Unfortunately, the compilation by Makin et al. (2014) contained chemical analyses performed at different laboratories using different analytical techniques (including laser ablation-inductively coupled plasma mass spectrometry (LA-ICP-MS), electron microprobe, neutron activation, and ICP-MS), and precision and accuracy varied accordingly. As an orientation survey, herein we present data from fi ve deposits, with two samples from the Rock Candy deposit (British Columbia), and one sample from each of Kootenay Florence (British Columbia), Eaglet (British Columbia), Eldor (Quebec), and Hastie quarry (Illinois) deposits (Table 1). The main objectives of this study are to: 1) assess variations in chemical composition of fl uorite in the samples and deposit types; 2) evaluate relations between analyses made using laser ablation-inductively coupled plasma mass spectrometry on individual grains [LA-ICP-MS(IG)], and those made using laser ablation-inductively coupled plasma mass spectrometry on fused beads [LA-ICP-MS(FB)] and X-ray fl uorescence (XRF); 3) test the use of stoichiometric Ca content as an internal fl uorite standard, such has been done by Gagnon et al. (2003) and Schwinn and Markl, (2005); 4) select the elements that are commonly present in concentrations above the lower limit of detection of LA-ICP-MS and available for constructing discrimination diagrams; 5) consider if our results agree with the preliminary discrimination diagrams of Makin et al. (2014).
DS200612-0513
2006
Mao, Q.Guo, Z., Wilson, M., Liu, J., Mao, Q.Post collisional, potassic and ultrapotassic magmatism of the northern Tibetan Plateau: constraints on characteristics of the mantle source, geodynamic upliftJournal of Petrology, Vol. 47, 6, pp. 1177-1220.Asia, TibetMagmatism - not specific to diamonds
DS201312-0347
2012
Mao, Q.Guo, S., Ye, K., Wu, Y., Chen, Y., Yang, Y., Zhang, L., Liu, J., Mao, Q., Ma, Y.A potential method to confirm the previous existence of lawsonite in eclogite: the mass imbalance of Sr and LREEs in multi stage epidote ( Ganghe, Dabie UHP terrane).Journal of Metamorphic Gology, Vol. 31, 4, pp. 415-435.ChinaUHP
DS201909-2093
2019
Mao, Q.Su, B., Chen, Y., Mao, Q., Zhang, D., Jia, L-H., Guo, S.Minor elements in olivine inspect the petrogenesis of orogenic peridotites. Dabie -SuluLithos, Vol. 344-345, pp. 207-216.ChinaUHP
DS201212-0083
2012
Mao, W.Boulard, E., Mao, W.Mg, Fe rich carbonates stability at lower mantle conditions.Goldschmidt Conference 2012, abstract 1p.MantlePerovskite
DS2002-0949
2002
Mao, W.L.Linn, J.F., Heintz, D.C., Campbell, A.J., Devine, J.M., Mao, W.L., Shen, G.Iron nickel alloy in the Earth's coreGeophysical Research Letters, Vol. 29,10,May15,pp.108-MantleCore-mantle boundary
DS200612-0862
2006
Mao, W.L.Mao, H-K., Mao, W.L.Core mantle interaction - the formation, elasticity, rheology and dynamics of iron rich silicate in core mantle boundary layer.International Mineralogical Association 19th. General Meeting, held Kobe, Japan July 23-28 2006, Abstract p. 126.MantleGeophysics - seismics, D layer
DS200612-0863
2006
Mao, W.L.Mao, W.L., Mao, H-K., Sturhahn, W., Zhao, J., Prakapenka, V.B., Meng, Y., Shu, J., Hemley, R.J.Iron rich post perovskite and the origin of ultralow-velocity zones.Science, Vol. 312, April 28, pp. 564-565.MantleGeophysics - seismics, silicate
DS201412-1024
2014
Mao, W.L.Zhang, L., Meng, Y., Yang, W.,Wang, L., Mao, W.L., Zeng, Q-S., Jeong, J.S., Wagner, A.J., Mkhoyan, K.A., Liu, W., Xu, R., Mao, H-K.Disproportionation of (Mg,Fe) SiO3 perovskite in Earth's deep lower mantle.Science, Vol. 344, no. 6186, pp. 877-882.MantlePerovskite
DS201809-2067
2018
Mao, W.L.Mao, W.L., Liu, J., Hu, Q.Hydrogen bearing iron peroxide in Earth's lowermost mantle.Goldschmidt Conference, 1p. AbstractMantleWater

Abstract: How water cycles through the Earth's interior, presumably is of fundamental importance for understanding the evolution of our planet. The presence of even trace amounts of water (or hydrogen) can dramatically affect many physical and chemical properties of Earth materials, such as phase stability conditions, viscosity, thermal conductivity, etc. Here, we report that the reaction between water and iron to form a pyrite-structured hydrogen-bearing iron peroxide, FeO2Hx (with x = 0 to 1), under the pressure-temperature conditions relevant to the Earth’s deep lower mantle. Combined with theoretical calculations and high-pressure experiments using laser-heated diamond anvil cells coupled with a suite of insitu and characterization techniques (e.g. nuclear resonant inelastic X-ray scattering spectroscopy, X-ray absorption spectroscopy, and X-ray diffraction), we find that this extremely oxygen-rich form of iron peroxide has properties consistent with ultralow velocity zones that are seismically observed at the core-mantle boundary. This phase may also have implications for deep volatile cycling and mantle redox.
DS201912-2799
2019
Mao, W.L.Liu, J., Hu, Q., Bi, W., Yang, L., Xiao, Y., Chow, P., Meng, Y., Prakapenka, V.B., Mao, H-K., Mao, W.L.Altered chemistry of oxygen and iron under deep Earth conditionsNature Communications, 8p. PdfMantlegeochemistry

Abstract: A drastically altered chemistry was recently discovered in the Fe-O-H system under deep Earth conditions, involving the formation of iron superoxide (FeO2Hx with x?=?0 to 1), but the puzzling crystal chemistry of this system at high pressures is largely unknown. Here we present evidence that despite the high O/Fe ratio in FeO2Hx, iron remains in the ferrous, spin-paired and non-magnetic state at 60-133?GPa, while the presence of hydrogen has minimal effects on the valence of iron. The reduced iron is accompanied by oxidized oxygen due to oxygen-oxygen interactions. The valence of oxygen is not -2 as in all other major mantle minerals, instead it varies around -1. This result indicates that like iron, oxygen may have multiple valence states in our planet’s interior. Our study suggests a possible change in the chemical paradigm of how oxygen, iron, and hydrogen behave under deep Earth conditions.
DS201812-2840
2018
Mao, X.Li, Y., Zhang, J., Mustofa, K.M.G., Wang, Y., Yu, S., Cai, Z., Li, P., Zhou, G., Fu, C., Mao, X.Petrogenesis of carbonatites in the Luliangshan region, North Qaidam, northern Tibet, China: evidence for recycling of sedimentary carbonate and mantle metasomatism within a subduction zone.Lithos, Vol. 322, pp. 148-165.China, Tibetcarbonatite

Abstract: Carbonatitic magmatism in subduction zones provides extremely valuable information on the cycling, behavior and storage of deep carbon within the Earth. It may also shed light on insights into crust-mantle interaction and mantle metasomatism within subduction zones. Origin of carbonatite has long been debated: all hypotheses need to reflect the different mineral assemblages and geochemical compositions of carbonatites and their diverse tectonic settings. Here we present a petrological, geochronological, geochemical and isotopic study of carbonatite bodies associated with orogenic peridotites, which occur as stocks or dykes with widths of tens to hundreds of meters in the Luliangshan region, North Qaidam, northern Tibet, China. On the basis of modal olivine (Ol) content, the studied samples were subdivided into two groups: Ol-poor carbonatite and Ol-rich carbonatite. Zircon grains from the Ol-poor carbonatite show detrital features, and yield a wide age spectrum between 400?Ma and 1000?Ma with a pronounced peak at ca. 410-430?Ma. By contrast, oscillatory zoned zircons and inherited cores show two relatively small Neoproterozoic age peaks at ca. 920 and 830?Ma. Zircon grains from the Ol-rich carbonatite sample are also distributed in a wide spectrum between 400 and 1000?Ma, with a pronounced peak at ca. 440?Ma and a slightly inferior peak at ca. 410?Ma. The oscillatory zoned zircons and inherited cores exhibit a smaller Neoproterozoic age peak at ca. 740?Ma. The pronounced peaks ranging from 430 to 410?Ma are consistent with the deep subduction and mantle metasomatic events recorded in associated ultramafic rocks. Both groups of carbonatites are characterized by enrichment of light rare earth elements (LREEs) with high (La/Yb)N values and pronounced negative Eu anomalies. They show high 87Sr/86Sr values (0.708156-0.709004), low 143Nd/144Nd values (0.511932-0.512013) and high ?18OV-SMOW values (+17.9 to +21.3‰). This geochemical and isotopic evidence suggests that these carbonatites were derived from remobilized sedimentary carbonate rocks. We propose that the primary carbonatite magma was formed by partial melting of sedimentary carbonates with mantle contributions. Sedimentary carbonates were subducted into the shallow upper mantle where they melted and formed diapirs that moved upwards through the hot mantle wedge. The case presented provides a rare example of carbonatite originating from sedimentary carbonates with mantle contributions and relevant information on the mantle metasomatism within a subduction zone.
DS201312-0540
2013
Mao, Z.Lin, J-F., Speciale, S., Mao, Z., Marquardt, H.Effects of the electronic spin transitions of iron in lower mantle minerals: implications for deep mantle geophysics and geochemistry.Reviews of Geophysics, Vol. 51, 2, pp. 244-275.MantleMineralogy
DS201412-0547
2014
Mao, Z.Mao, Z., Lin, J-F., Yang, J., Bian, H., Liu, J., Watson, H.C., Huang, S., Chen, J., Prakapenka, V.B., Xiao, Y., Chow, P.Fe, Al bearing post-perovskite in the Earth's lower mantle.Earth and Planetary Science Letters, Vol. 403, pp. 157-163.MantlePerovskite
DS201805-0981
2018
Mao, Z.Sun, N., Wei, W., Han, S., Song, J., Li, X., Duan, Y., Prakapenka, V.B., Mao, Z.Phase transition and thermal equations of state of (Fe, Al) -bridgmanite and post perovskite: implication for the chemical heterogeneity at the lowermost mantle.Earth Planetary Science Letters, Vol. 490, pp. 161-169.Mantleperovskite
DS201901-0046
2018
Mao, Z.Lin, J-F, Mao, Z., Yang, J., Fu, F.Elasticity of lower-mantle bridgemanite.Nature, Vol. 564, pp. E18-E26.Mantlebridgmanite
DS201901-0083
2018
Mao, Z.Sun, N., Wei, W., Han, S., Song, J., Li, X, Duan, Y., Prakapenka, V.B., Mao, Z.Phase transition and thermal equations of state of ( Fe, Al) - bridgmanite and post-perovskite: implication for the chemical heterogeneity at the lowermost mantle.Earth and Planetary Science Letters, Vol. 490, 1, pp. 161-169.Mantlegeothermometry

Abstract: In this study, we have determined the phase boundary between Mg0.735Fe0.21Al0.07Si0.965O3-Bm and PPv and the thermal equations of state of both phases up to 202 GPa and 2600 K using synchrotron X-ray diffraction in laser heated diamond anvil cells. Our experimental results have shown that the combined effect of Fe and Al produces a wide two-phase coexistence region with a thickness of 26 GPa (410 km) at 2200 K, and addition of Fe lowers the onset transition pressure to 98 GPa at 2000 K, consistent with previous experimental results. Furthermore, addition of Fe was noted to reduce the density (?) and bulk sound velocity () contrasts across the Bm-PPv phase transition, which is in contrast to the effect of Al. Using the obtained phase diagram and thermal equations of state of Bm and PPv, we have also examined the effect of composition variations on the ? and profiles of the lowermost mantle. Our modeling results have shown that the pyrolitic lowermost mantle should be highly heterogeneous in composition and temperature laterally to match the observed variations in the depth and seismic signatures of the D? discontinuity. Normal mantle in a pyrolitic composition with ?10% Fe and Al in Bm and PPv will lack clear seismic signature of the D? discontinuity because the broad phase boundary could smooth the velocity contrast between Bm and PPv. On the other hand, Fe-enriched regions close to the cold slabs may show a seismic signature with a change in the velocity slope of the D? discontinuity, consistent with recent seismic observations beneath the eastern Alaska. Only regions depleted in Fe and Al near the cold slabs would show a sharp change in velocity. Fe in such regions could be removed to the outer core by strong core-mantle interactions or partitions together with Al to the high-pressure phases in the subduction mid ocean ridge basalts. Our results thus have profound implication for the composition of the lowermost mantle.
DS202005-0747
2020
Mao, Z.Lin, J-F., Mao, Z., Yang, J., Fu, S.Elasticity of lower-mantle bridgmanite.Nature, Vol. 564, 7736, doi:10.1038/s41586-018-0741-7Mantlebridgmanite
DS1998-0609
1998
Mao., H.K.Hemley, R.J., Mao., H.K.X rays on deep mantle and core dynamicsIma 17th. Abstract Vol., p. A 36, abstractMantleGeodynamics
DS200412-0962
2004
Maoshuang, K.Katusra, T., Yamada, H., Nishikawa, O., Maoshuang, K., et al.Olivine wadsleyite transition in the system MgFe 2SiO4.Journal of Geophysical Research, Vol. 109, B2, 10.1029/2003 JB002438TechnologyMineral chemistry
DS201412-0248
2015
Mapani, B.Foster, D.A., Goscombe, B.D., Newstead, B., Mapani, B., Mueller, P.A., Gregory, L.C., Muvangua, E.U-Pb age and Lu-Hf isotopic dat a of detrital zircons from the Neoproterozoic Damara sequence: implications for Congo and Kalahari before Gondwana.Gondwana Research, Vol. 28, 1, pp. 179-190.AfricaGeochronology
DS2001-0828
2001
Mapasa, K.Nesbit, P.Q., Du Toit, G., Mapasa, K., Feldman, C.Evaluation of the Hicom 120 mill at Venetia mineMinerals Eng., Vol. 14, No. 7, pp. 711-21.South AfricaMining - mineral processing, comminution, Deposit - Venetia
DS200412-1222
2004
Mapeo, R.B.M.Mapeo, R.B.M., Armstrong, R.A., Kampunzu, A.B., Ramokate, L.V.SHRIMP U Pb zircon ages of granitoids from the western domain of the Kaapvaal Craton, southeastern Botswana: implications for crSouth African Journal of Geology, Vol. 107, 1/2, pp. 159-172.Africa, BotswanaGeochronology, tectonics
DS201312-0593
2013
Mapeo, R.B.M.McCourt, S., Armstrong, R.A., Jelsma, H., Mapeo, R.B.M.New U-Pb SHRIMP ages from the Lubango region, sw Angola: insights into the Paleoproterozoic evolution of the Angolan shield, southern Congo craton, Africa.Journal of the Geological Society, Vol. 170, pp. 353-363.Africa, AngolaGeochronology
DS201708-1708
2017
Maphane, K.Maphane, K.Evolution of the Orapa A/K1 geology model - insights from analysis of multi-disciplinary datasets.11th. International Kimberlite Conference, OralAfrica, BotswanaDeposit - Orapa A/K1
DS201710-2236
2017
Maphane, K.Kruger, K., Maphane, K.Desert Gems: Bostwana's major mines. Orapa, Letlhakane and Damtshaa mines.11th International Kimberlite Field Trip Guide, Sept. 23p. PdfAfrica, Botswanadeposit - Orapa, Letlhakane, Damtshaa
DS202006-0936
2020
Mapurisa, W.Mhangara, P., Tsoeleng, L.T., Mapurisa, W.Monitoring the development of artisanal mines in South Africa.Journal of the Southern African Institute of Mining and Metallurgy, Vol. 120, pp. 299- 307. pdfAfrica, South Africaremote sensing
DS1920-0240
1925
MaquassiMaquassiConditions on the Alluvial Diamond Fields. #2Mining Engineering Journal of South Africa, Vol. 36, PT. 1, MAY 30TH. P. 376.South AfricaPolitics
DS1992-0992
1992
Maquire, D.J.Maquire, D.J.The raster GIS design model- a profile of ERDASComputers and Geosciences, Vol. 18, No. 4, pp. 463-470GlobalComputer, Program -Geographic information systems -ERDAS
DS1992-1253
1992
Maquire, D.J.Raper, J.F., Maquire, D.J.Design models and functionality in GISComputers and Geosciences, Vol. 18, No. 4, pp. 387-394GlobalComputer, Program -Geographic information systems -design models
DS201806-1234
2018
Maquire, R.Maquire, R., Ritsema, J., Bonnin, M., van Keken, P.E., Goes, S.Evaluating the resolution of deep mantle plumes in teleseismic traveltime tomography.Journal of Geophysical Research, Vol. 123, 1. pp. 384-400.Mantlegeophysics - seismic

Abstract: The strongest evidence to support the classical plume hypothesis comes from seismic imaging of the mantle beneath hot spots. However, imaging results are often ambiguous and it is questionable whether narrow plume tails can be detected by present?day seismological techniques. Here we carry out synthetic tomography experiments based on spectral element method simulations of seismic waves with period T > 10 s propagating through geodynamically derived plume structures. We vary the source?receiver geometry in order to explore the conditions under which lower mantle plume tails may be detected seismically. We determine that wide?aperture (4,000-6,000 km) networks with dense station coverage (<100-200 km station spacing) are necessary to image narrow (<500 km wide) thermal plume tails. We find that if uncertainties on traveltime measurements exceed delay times imparted by plume tails (typically <1 s), the plume tails are concealed in seismic images. Vertically propagating SKS waves enhance plume tail recovery but lack vertical resolution in regions that are not independently constrained by direct S paths. We demonstrate how vertical smearing of an upper mantle low?velocity anomaly can appear as a plume originating in the deep mantle. Our results are useful for interpreting previous plume imaging experiments and guide the design of future experiments.
Author Index
A-An Ao+ B-Bd Be-Bk Bl-Bq Br+ C-Cg Ch-Ck Cl+ D-Dd De-Dn Do+ E F-Fn Fo+ G-Gh Gi-Gq Gr+ H-Hd He-Hn Ho+ I J K-Kg Kh-Kn Ko-Kq Kr+ L-Lh
Li+ M-Maq Mar-Mc Md-Mn Mo+ N O P-Pd Pe-Pn Po+ Q R-Rh Ri-Rn Ro+ S-Sd Se-Sh Si-Sm Sn-Ss St+ T-Th Ti+ U V W-Wg Wh+ X Y Z
 
 

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