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SDLRC - Scientific Articles all years by Author - J


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.
Searching this page for a specific term or authorIn your Firefox browser click Edit in the menu bar and then Find. In the Find box that shows up at the bottom of the web page enter your search term. Firefox will highlight all occurrences. This is particularly helpful when the author you are seeking was not the lead author by whom the compilation is sorted.
Sending or sharing a referenceThe left column (Posted/Published) has an embedded hyperlink for each reference. In Firefox, if you right click on it, you can obtain the link url for that reference's location within the page, which you can copy and paste into an email or any other document. You can also use the "share this link" option to tweet, facebook etc the link.
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 - J
Posted/
Published
AuthorTitleSourceRegionKeywords
DS201904-0758
2019
J.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 F = 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.
DS1975-1081
1979
J.C. Hill &associationJ.C. Hill &associationProposals for the Survey and Evaluation of Offshore Diamondiferous Gravel Deposits in the Hondeklipbaai Area of South Africa.Unpubl. Report., 20P.South AfricaProspecting, Exploration
DS1860-0631
1889
Jaap, A.H.Jaap, A.H.Days with Industrials. Adventures and Experiences Among Curious Industries.London: Trubner And Co., Africa, South AfricaTravelogue
DS201505-0242
2015
Jablon, M.Jablon, M., Navon, O.The role of high density Micro inclusion fluids in the growth of monocrystalline diamonds.Israel Geological Society, Abstracts 1p.Africa, Guinea, South AfricaFibrous diamonds
DS1996-0712
1996
JablonskiKamperman, M., Danyushevskey, L.V., Taylor, W., JablonskiDirect oxygen measurements of chromium rich spinel: implications for spinelstoichiometry.American Mineralogist, Vol. 81, Sept-Oct., pp. 1186-1194.AustraliaDiamond indicator spinel, Deposit -Aries, Argyle
DS1984-0118
1984
Jablonwo, J.Ashburn, A., Jablonwo, J.Japan Pushes into Diamond TurningAmerican Machinery, Vol. 128, No. 12, DECEMBER PP. 75-79.JapanIndustrial
DS1995-0800
1995
Jachens, R.C.Hildenbrand, T.G., Jachens, R.C., Simpson, R.W.Insights on lithospheric structures within the stable craton, USA based on magnetic and gravity data.Iagod Giant Ore Deposits Workshop, J. Kutina, 6p.MidcontinentCraton, Geophysics -magnetics, gravity
DS1997-0505
1997
Jachens, R.C.Hildenbrand, T.G., Jachens, R.C., Simpson, R.W.Insights on lithospheric structures within the stable craton USA, based on magnetic and gravity data.Global Tectonics and Metallogeny, Vol. 6, No. 2, March pp. 113-118.MidcontinentMantle structure, Geophysics - magnetics, gravity
DS1860-0758
1892
Jack, R.L.Jack, R.L.On the Sapphire Deposits and the Gold and Silver Mines Near west Marsfield. GilbertonQueensland Geological Survey Publn., No. 16, P. 81.Australia, QueenslandSapphire
DS1989-1406
1989
JacksonSmith, C.B., Allsopp, H.L., Garvie, O.G., Kramers, J.D., JacksonNote on the uranium-lead (U-Pb) (U-Pb) perovskite method for dating kimberlites: examples fromChemical Geology, Vol. 79, pp. 137-145South Africa, Northwest TerritoriesGeochronology, Perovskite
DS1997-1211
1997
JacksonVilleneuve, M.E., Henderson, J.R., Hrabi, R.B., Jackson2.80-2.58 Ga plutonism and volcanism in the Slave ProvinceGeological Survey of Canada (GSC) Paper, No. 1997-F, pp. 37-60.Northwest TerritoriesGeochronology, Craton - Slave
DS1997-1212
1997
JacksonVilleneuve, M.E., Henderson, J.R., Hrabi, R.B., Jackson2.70 - 2.58 Ga plutonism and volcanism in the Slave Province, District ofMackenzie, Northwest Territories.Geological Society of Canada (GSC) Paper, No. 1997-F, p. 37-60.Northwest TerritoriesGeochronology, Magma activity
DS2001-0102
2001
JacksonBelousova, E.A., Griffin, W.L., Shee, Jackson, O'ReillyTwo age populations of zircons from the Timber Creek kimberlites, as determined by laser ablation ICP MSAustralian Journal of Earth Sciences, Vol. 48, No. 5, Oct. pp. 757-766.AustraliaGeochronology, Deposit - Timber Creek
DS2002-0614
2002
JacksonGriffin, W.L., Wang, X., Jackson, Pearson, O'Reilly, XuZircon chemistry and magma mixing, SE China: in situ analysis of Hf isotopes, Tonglu and Pingtan complexes.Lithos, Vol.61, No.1-4, pp. 237-69., Vol.61, No.1-4, pp. 237-69.China, SoutheastGeochemistry - magma mixing, Geochronology
DS2002-0615
2002
JacksonGriffin, W.L., Wang, X., Jackson, Pearson, O'Reilly, XuZircon chemistry and magma mixing, SE China: in situ analysis of Hf isotopes, Tonglu and Pingtan complexes.Lithos, Vol.61, No.1-4, pp. 237-69., Vol.61, No.1-4, pp. 237-69.China, SoutheastGeochemistry - magma mixing, Geochronology
DS2002-1236
2002
JacksonPearson, N.J., Alard, O., Griffin, Jackson, O'ReillyIn situ measurement of Re Os isotopes in mantle sulfides by laser ablation multicollector inductively..Geochimica et Cosmochimica Acta, Vol. 66, 6, pp. 1037-50.Russia, Siberia, Northwest TerritoriesCraton - mass spectrometry, rhenium, osmium, Peridotites
DS2002-1685
2002
JacksonWang, X., Griffin, O'Reilly, Zhou, Xu, Jackson, PearsonMorphology and geochemistry of zircons from late Mesozoic igneous complexes in coastal SE China:Mineralogical Magazine, Vol.66,2,pp. 235-52., Vol.66,2,pp. 235-52.China, southeastPetrogenesis
DS2002-1686
2002
JacksonWang, X., Griffin, O'Reilly, Zhou, Xu, Jackson, PearsonMorphology and geochemistry of zircons from late Mesozoic igneous complexes in coastal SE China:Mineralogical Magazine, Vol.66,2,pp. 235-52., Vol.66,2,pp. 235-52.China, southeastPetrogenesis
DS200712-0204
2007
JacksonCourtier, A.M., Jackson, Lawrence, Wang, Lee, Halama, Warren, Workman, Xu, Hirschmann, Larson, Hart, Lithgo-Bertelloni, Stixrude, ChenCorrelation of seismic and petrologic thermometers suggests deep thermal anomalies beneath hotspots.Earth and Planetary Science Letters, Vol. 264, 1-2, pp. 308-316.MantleGeothermometry
DS1991-0775
1991
Jackson, .E.Jackson, .E.A user's guide to principal componentsWiley Interscience, 569p. approx. $ 70.00GlobalGeostatistics, Book Review
DS1991-0131
1991
Jackson, A.Bloxham, J., Jackson, A.Fluid flow near the surface of earth's outer coreReviews of Geophysics, Vol. 29, No. 1, February pp. 97-120GlobalEarth's core, Core/mantle
DS201509-0415
2015
Jackson, A-L.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.
DS201708-1676
2017
Jackson, C.Jackson, C.New insights into volatile-rich mantle metasomatism at the Bultfontein diamond mine, Kimberley, South Africa.11th. International Kimberlite Conference, PosterAfrica, South Africadeposit - Bultfontein
DS201709-2002
2017
Jackson, C.Jackson, C., Gibson, S.New insights into sulfur-rich mantle metasomatism at Bultfontein, Kimberley.Goldschmidt Conference, abstract 1p.Africa, South Africadeposit - Bultfontein

Abstract: Metasomatised regions of Earth’s sub-continental lithospheric mantle potentially represent a large volatile reservoir. Nevertheless, the mechanisms involved in the storage and upward transport of volatiles such as C and S, from the convecting mantle and/or subducting slabs, are poorly understood. We have carried out a systematic microanalytical study of a suite of sulfide-rich mantle peridotites from the Bultfontein diamond mine, Kimberley. EDS mapping of large (>2mm), interstitial base metal sulfides in the Bultfontein xenoliths has identified distinct Ni-rich regions (pentlandite). The Ni-rich sulfides are adjacent to olivine with Ni poor rims (<0.2 wt% NiO). Diffusion profiles between the protolith olivines and adjacent sulfides are used to estimate the timing of the S-rich metasomatic event. The presence of large unequilibrated olivine indicates that Nisulfides were introduced immediately prior to kimberlite emplacement. The calculated composition of melt in equilibrium with metasomatic clinopyroxenes in the Bultfontein sulphide-bearing peridotites shows a strong correlation to high-density carbonatitic fluids trapped in diamonds. This association is extended by the wealth of metasomatic sulfides in the Bultfontein xenoliths. Moreover, Ni-rich sulfides (~25 wt%) are the most common mineral inclusion in peridotitic diamonds, implying that diamonds crystallise from a S-saturated fluid. Many studies attribute the metasomatism at Bultfontein to silicate melts associated with the kimberlite, but we explore the possibility of metasomatism by reactive percolation of a volatile-rich agent with carbonatitic affinity. The S-rich nature of the metasomatism and the correlation with diamond high-density fluids has great implications for the transport of volatiles from the deep mantle to shallow regions of the craton.
DS201807-1510
2018
Jackson, C.A-L.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.
DS201810-2331
2018
Jackson, C.G.Jackson, C.G., Gibson, S.A.Preservation of systematic Ni and Cr heterogeneity in otherwise homogeneous mantle olivine: implications for timescales of post-metasomatism re-equilibration.Lithos, Vol. 318-319. pp. 448-463.Africa, South Africadeposit - Bultfontein

Abstract: The flux of elements into Earth's sub-continental lithospheric mantle is facilitated by the passage of small-fraction melts that either crystallise new phases or react with pre-existing minerals.Metasomatised peridotite records the end product of this exchange but rarely captures the process in the act due to subsolidus re-equilibration. We present the results of a systematic investigation of a metasomatic melt channel preserved in a mantle peridotite from the Late Cretaceous Bultfontein kimberlite (Kaapvaal craton) that shows rare direct evidence of the melt-rock reaction processes. We show that the metasomatic proto-kimberlite melt underwent variable crystallisation of clinopyroxene, sulfides, phlogopite, spinel and zircon together with interaction and diffusive exchange with the surrounding olivine-rich mantle. Element profiles across large olivine porphyroclasts (Fo88) show significant core-to-rim variations in Ni (NiO?=?0.18-0.32?wt%) and Cr (Cr?=?35-60?ppm), while concentrations of all other elements (e.g. Mg, Fe, Mn, Co, V)are remarkably homogeneous. Electron backscatter diffraction analysis shows that the disequilibrium of Ni and Cr is greatest where the crystal contains large components of the [100] and [010] axes. The disequilibrium is preserved in certain orientations because diffusion of Ni and Cr in olivine is more anisotropic than Fe-Mg and Mn, and slower in the [100] and [010] directions. We present the first observations of Ni and Cr decoupling from other elements in mantle olivine and suggest that this is a consequence of: (i)changing mineral-melt concentration gradients associated with the reactive percolation of a precursory kimberlite melt; and (ii) late-stage sulfide and spinel precipitation. We use the diffusion limited re-equilibration of Ni in olivine to quantify the timing of metasomatism prior to xenolith entrainment by the host kimberlite. Our modelling indicates that reactive percolation occurred on the order of 103-105?years prior to entrainment; this provides an additional line of support for the hypothesis that a period of metasomatism by proto-kimberlite melts precedes the final kimberlite ascent to the surface. The broader implication of our finding of variable rates of minor element diffusion in natural olivine is that it highlights the importance of anisotropy and the impact of changing local concentration gradients during subsolidus re-equilibration.
DS201812-2821
2018
Jackson, C.G.Jackson, C.G., Gibson, S.A.Preservation of systematic Ni and Cr heterogeneity in otherwise homogeneous mantle olivine: implications for timescales of post-metasomatism re-equilibrium.Lithos, Vol. 318-319, pp. 448-463.Africa, South Africadeposit - Bultfontein

Abstract: The flux of elements into Earth’s sub-continental lithospheric mantle is facilitated by the passage of small-fraction melts that either crystallise new phases or react with pre-existing minerals. Metasomatised peridotite records the end product of this exchange but rarely captures the process in the act due to subsolidus re-equilibration. We present the results of a systematic investigation of a metasomatic melt channel preserved in a mantle peridotite from the Late Cretaceous Bultfontein kimberlite (Kaapvaal craton) that shows rare direct evidence of the melt-rock reaction processes. We show that the metasomatic proto-kimberlite melt underwent variable crystallisation of clinopyroxene, sulfides, phlogopite, spinel and zircon together with interaction and diffusive exchange with the surrounding olivine-rich mantle. Element profiles across large olivine porphyroclasts (Fo88) show significant core-to-rim variations in Ni (NiO = 0.18-0.32 wt.%) and Cr (Cr = 35-60 ppm), while concentrations of all other elements (e.g. Mg, Fe, Mn, Co, V) are remarkably homogeneous. Electron backscatter diffraction analysis shows that the disequilibrium of Ni and Cr is greatest where the crystal contains large components of the [100] and [010] axes. The disequilibrium is preserved in certain orientations because diffusion of Ni and Cr in olivine is more anisotropic than Fe-Mg and Mn, and slower in the [100] and [010] directions. We present the first observations of Ni and Cr decoupling from other elements in mantle olivine and suggest that this is a consequence of: (i) changing mineral-melt concentration gradients associated with the reactive percolation of a precursory kimberlite melt; and (ii) late-stage sulfide and spinel precipitation. We use the diffusion limited re-equilibration of Ni in olivine to quantify the timing of metasomatism prior to xenolith entrainment by the host kimberlite. Our modelling indicates that reactive percolation occurred on the order of 103-105 years prior to entrainment; this provides an additional line of support for the hypothesis that a period of metasomatism by proto-kimberlite melts precedes the final kimberlite ascent to the surface. The broader implication of our finding of variable rates of minor element diffusion in natural olivine is that it highlights the importance of anisotropy and the impact of changing local concentration gradients during subsolidus re-equilibration.
DS201803-0455
2018
Jackson, C.R.Jackson, C.R., Bennett, N.R., Du, Z., Cottrell, E., Fei, Y.Early episodes of high pressure core formation preserved in plume mantle.Nature , Vol. 553, 7689, pp. 491-495.Mantleplumes

Abstract: The decay of short-lived iodine (I) and plutonium (Pu) results in xenon (Xe) isotopic anomalies in the mantle that record Earth’s earliest stages of formation1,2,3,4,5,6,7,8. Xe isotopic anomalies have been linked to degassing during accretion2,3,4, but degassing alone cannot account for the co-occurrence of Xe and tungsten (W) isotopic heterogeneity in plume-derived basalts9,10 and their long-term preservation in the mantle. Here we describe measurements of I partitioning between liquid Fe alloys and liquid silicates at high pressure and temperature and propose that Xe isotopic anomalies found in modern plume rocks (that is, rocks with elevated 3He/4He ratios) result from I/Pu fractionations during early, high-pressure episodes of core formation. Our measurements demonstrate that I becomes progressively more siderophile as pressure increases, so that portions of mantle that experienced high-pressure core formation will have large I/Pu depletions not related to volatility. These portions of mantle could be the source of Xe and W anomalies observed in modern plume-derived basalts2,3,4,9,10. Portions of mantle involved in early high-pressure core formation would also be rich in FeO11,12, and hence denser than ambient mantle. This would aid the long-term preservation of these mantle portions, and potentially points to their modern manifestation within seismically slow, deep mantle reservoirs13 with high 3He/4He ratios.
DS201706-1104
2017
Jackson, C.R.M.Smye, A.J., Jackson, C.R.M., Konrad-Schnolke, M., Hesse, M.A., Parman, S.W., Shuster, D.L., Ballentine, C.J.Noble gases recycled into the mantle through cold subduction zones.Earth and Planetary Science Letters, Vol. 471, pp. 65-73.Mantlegeochemistry, water cycle

Abstract: Subduction of hydrous and carbonated oceanic lithosphere replenishes the mantle volatile inventory. Substantial uncertainties exist on the magnitudes of the recycled volatile fluxes and it is unclear whether Earth surface reservoirs are undergoing net-loss or net-gain of H2O and CO2. Here, we use noble gases as tracers for deep volatile cycling. Specifically, we construct and apply a kinetic model to estimate the effect of subduction zone metamorphism on the elemental composition of noble gases in amphibole - a common constituent of altered oceanic crust. We show that progressive dehydration of the slab leads to the extraction of noble gases, linking noble gas recycling to H2O. Noble gases are strongly fractionated within hot subduction zones, whereas minimal fractionation occurs along colder subduction geotherms. In the context of our modelling, this implies that the mantle heavy noble gas inventory is dominated by the injection of noble gases through cold subduction zones. For cold subduction zones, we estimate a present-day bulk recycling efficiency, past the depth of amphibole breakdown, of 5-35% and 60-80% for 36Ar and H2O bound within oceanic crust, respectively. Given that hotter subduction dominates over geologic history, this result highlights the importance of cooler subduction zones in regassing the mantle and in affecting the modern volatile budget of Earth's interior.
DS202012-2221
2021
Jackson, C.R.M.Jackson, C.R.M., Cottrell, E., Andrews, B.Warm and oxidizing slabs limit ingassing efficiency of nitrogen to the mantle.Earth and Planetary Letters, Vol. 553, 116515, 12p. PdfMantlenitrogen

Abstract: Nitrogen is a major and essential component of Earth's atmosphere, yet relative to other volatile elements, there are relatively few experimental constraints on the pathways by which nitrogen cycles between Earth's interior and exterior. We report mineral-melt and mineral-fluid partitioning experiments to constrain the behavior of nitrogen during slab dehydration and sediment melting processes. Experiments reacted rhyolitic melts with silicate and oxide minerals, in the presence of excess aqueous fluid, over temperatures between 725-925 °C and pressures between 0.2 and 2.3 GPa. Oxygen fugacity ranged between iron metal saturation (~NNO-5) to that in excess of primitive arc basalts (~NNO+2). Our experiments demonstrate that hydrous fluid is the preferred phase for nitrogen over minerals (biotite, K-feldspar, and amphibole) and rhyolitic melts across all conditions explored. Relatively large effects of pressure (?log()/?(GPa/K) = 761 ± 68 (1s), ?log()/?(GPa/K) = 462 ± 169) and moderate effects of oxygen fugacity (NNO = -0.20 ± 0.04, ?logNNO = -0.10 ± 0.04) modulate partitioning of nitrogen. We further document negligible partitioning effects related to mineral composition or Cl content of hydrous fluid. Of the minerals investigated, biotite has the largest affinity for N and should control the retention of N in slabs where present. Application of partitioning data to slab dehydration PT paths highlights the potential for highly incompatible behavior ( < 0.1) from the slab along warmer and oxidized (NNO+1) subduction geotherms, whereas dehydration along reduced and cooler geotherms will extract moderate amounts of nitrogen ( > 0.1). We find that slab melting is less effective at extracting N from slabs than fluid loss, at least under oxidized conditions (NNO+1). Ultimately, the conditions under which slabs lose fluid strongly affect the distribution of nitrogen between Earth's interior and exterior.
DS1859-0133
1859
Jackson, C.T.Jackson, C.T.Sur la Bornite de DahlOnega et sur Les Diamants de l'etat De Georgie.Academy of Science Paris COMPTES RENDUS, Vol. 48, PP. 850-851. ALSO American Journal of Science, N.S. 2, Vol. 27United States, Appalachia, GeorgiaDiamond Occurrence
DS201212-0361
2012
Jackson, D.Kjarsgaard, B.A., Mather, D.G., Pearson, S., Jackson, D., Crabtree, D., Creighton, S.CR-diopside and Cr-pyrope xenocryst thermobarometry revisited: applications to lithosphere studies and diamond exploration.10th. International Kimberlite Conference Feb. 6-11, Bangalore India, AbstractCanadaGeobarometry
DS1982-0290
1982
Jackson, D.E.Jackson, D.E.Petrogenesis of a shallow level kimberlite from Taughannock Creek, NewYorkMsc. Thesis University of Of Tennessee, Knoxville, Tn, 71pGlobalKimberlite, Petrology
DS1982-0291
1982
Jackson, D.E.Jackson, D.E., Hunter, R.H., Taylor, L.A.A Mesozoic Window Into the Sub-appalachian Mantle: Kimberlite from the Eastern United States.Geological Society of America (GSA), Vol. 14, No. 1-2, P. 28, (abstract.).United States, Appalachia, New YorkKimberlite, Dike, Devonian, Shale, Garnet
DS1982-0292
1982
Jackson, D.E.Jackson, D.E., Hunter, R.H., Taylor, L.A.Shallow Level Kimberlite from the Northeastern United States (us): an Unusual Mantle Sample.Eos, Vol. 63, PP. 463-464.United States, Appalachia, New YorkBlank
DS1986-0326
1986
Jackson, D.G.Haebig, A.E., Jackson, D.G.Geochemical expression of some west Australian kimberlites andlamproitesProceedings of the Fourth International Kimberlite Conference, Held Perth, Australia, No. 16, pp. 466-468AustraliaDiamond exploration
DS1970-0101
1970
Jackson, E.D.Jackson, E.D., Wright, T.L.Xenoliths in the Honolulu Volcanic Series, HawaiiJournal of Petrology, Vol. 11, P. 405.United States, HawaiiBlank
DS1989-0367
1989
Jackson, G.D.Dostal, J., Jackson, G.D., Galley, A.Geochemistry of Neohelikian Nauyat plateau basalts, Borden rift basin, northwestern Baffin Island.Canadian Journal of Earth Sciences, Vol. 26, pp. 2214-23.Northwest Territories, Baffin IslandBasalts
DS1995-0570
1995
Jackson, G.D.Frisch, T., Jackson, G.D., et al.uranium-lead (U-Pb) ages of zircon from the Kolvitsa gabbro anorthosite complex, southern Kola PeninsulaPetrology, Vol. 3, No. 3, May-June pp. 219-225RussiaGeochronology, Anorthosite
DS2000-0436
2000
Jackson, G.D.Jackson, G.D., Berman, R.G.Precambrian metamorphic and tectonic evolution of northern Baffin Island, Nunuvut Canada.Can. Mineralog., Vol. 38, No. 2, Apr. pp. 399-422.Northwest Territories, Nunavut, Baffin IslandTectonics - metamorphism
DS200612-1358
2006
Jackson, G.D.St.Onge, M.R., Jackson, G.D., Henderson, I.Geology, Baffin Island south of 70 N and east of 80 W.Geological Survey of Canada, No. 4931, 1 CD $ 9.10Canada, NunavutBedrock data
DS1992-0761
1992
Jackson, H.R.Jackson, H.R., Dickie, K., Marillier, F.A seismic reflection study of northern Baffin Bay: implication for tectonicevolutionCanadian Journal of Earth Sciences, Vol. 29, No. 11, November, pp. 2353-2369GlobalGeophysics -seismics, Tectonics
DS1994-0813
1994
Jackson, H.R.Jackson, H.R., Reid, I.Crustal thickness variations between Greenland and Ellesmere Island margins detremined from seismic...Canadian Journal of Earth Sciences, Vol. 31, pp. 1407-18.Greenland, Northwest Territories, Ellesmere IslandGeophysics - seismics, Crust
DS1990-0749
1990
Jackson, I.Jackson, I., Rudnick, R.L., O'Reilly, S.Y., Bezant, C.Measured and calculated elastic wave velocities for xenoliths from the lower crust and upper mantleTectonophysics, Vol. 174, No. 1/2, March 1, pp. 207-210GlobalMantle, Xenoliths -physics
DS1991-1424
1991
Jackson, I.Rigden, S.M., Gwanmesia, G.D., Fitzgerald, J.D., Jackson, I.Spinel elasticity and seismic structure of the transition zone of themantleNature, Vol. 354, No. 6349, Nove. 14, pp. 143-145MantleSpinels, Geophysics -seismics
DS1996-0671
1996
Jackson, I.Jackson, I.The composition of the earth's mantle: insights from laboratory measurements of seismic wave speeds.Geological Society of Australia 13th. Convention held Feb., No. 41, abstracts p.215.MantleGeophysics -seismic, Lithosphere
DS2000-0437
2000
Jackson, I.Jackson, I.Geophysics: taking the Earth's temperatureNature, Vol. 406, No. 6795, Aug. 3, p. 470.GlobalGeophysics, Geothermometry
DS2000-0545
2000
Jackson, I.Kung, J., Rogden, S.M., Jackson, I.Silicate perovskite analogue ScALO3; temperature dependence of elastic moduli.Physical Earth and Planetary Interiors, Vol. 120, No. 4, Aug. 1, pp. 299-314.GlobalPerovskite - experimental petrology
DS2001-0410
2001
Jackson, I.Gregoire, M., Jackson, I., O'Reilly, S.Y., Cottin, J.Y.The lithospheric mantle beneath Kerguelen Islands: petrological and petrophysical characteristics....Contributions to Mineralogy and Petrology, Vol. 142, No. 2, Nov. pp. 244-59.Indian Ocean, Kerguelen IslandsMantle mafic rock types - correlation with profiles, Geophysics - seismics
DS200412-0535
2004
Jackson, I.Faul, U., Jackson, I., Fitzgerald, J.Viscoelasticity of olivine and implications for the upper mantle.Lithos, ABSTRACTS only, Vol. 73, p. S33. abstractUnited States, New MexicoSan Carlos olivine
DS200512-0280
2005
Jackson, I.Faul, U.H., Jackson, I.The seismological signature of temperature and grain size variations in the upper mantle.Earth and Planetary Science Letters, Vol. 234, 1-2, pp. 119-134.MantleGeophysics - seismics
DS200612-0816
2006
Jackson, I.Liebermann, R.C., Kung, J., Li, B., Jackson, I.Elastic properties of pyroxene polymorphs of MgSiO3 and implications for seismic models and discontinuities in the Earth's upper mantle.Geochimica et Cosmochimica Acta, Vol. 70, 18, p. 18, abstract only.MantleGeophysics - seismic
DS201804-0681
2018
Jackson, I.Cline, C.J. II, Faul, U.H., David, E.C., Berry, A.J., Jackson, I.Redox influenced seismic properties of upper mantle olivine.Nature, Vol. 555, March 15, pp. 255-258.Mantlegeophysics - seismics

Abstract: Lateral variations of seismic wave speeds and attenuation (dissipation of strain energy) in the Earth’s upper mantle have the potential to map key characteristics such as temperature, major-element composition, melt fraction and water content1,2,3. The inversion of these data into meaningful representations of physical properties requires a robust understanding of the micromechanical processes that affect the propagation of seismic waves2,3. Structurally bound water (hydroxyl) is believed to affect seismic properties2,3 but this has yet to be experimentally quantified. Here we present a comprehensive low-frequency forced-oscillation assessment of the seismic properties of olivine as a function of water content within the under-saturated regime that is relevant to the Earth’s interior. Our results demonstrate that wave speeds and attenuation are in fact strikingly insensitive to water content. Rather, the redox conditions imposed by the choice of metal sleeving, and the associated defect chemistry, appear to have a substantial influence on the seismic properties. These findings suggest that elevated water contents are not responsible for low-velocity or high-attenuation structures in the upper mantle. Instead, the high attenuation observed in hydrous and oxidized regions of the upper mantle (such as above subduction zones) may reflect the prevailing oxygen fugacity. In addition, these data provide no support for the hypothesis whereby a sharp lithosphere-asthenosphere boundary is explained by enhanced grain boundary sliding in the presence of water.
DS1989-0404
1989
Jackson, J.England, P., Jackson, J.Active deformation of the continentsAnnual Rev. Earth. Planet. Sci, Vol. 17, pp. 197-226GlobalTectonics, Mantle
DS1993-0727
1993
Jackson, J.Jackson, J., Blenkinsop, T.The Malawi Earthquake of March 10, 1989: deep faulting within the East African Rift systemTectonics, Vol. 12, No. 5, Oct. pp. 1131-39.East Africa, MalawiTectonics, Rifting
DS2002-0755
2002
Jackson, J.Jackson, J.Faulting, flow and the strength of the continental lithosphereInternational Geology Review, Vol. 44, 1, pp. 39-61.India, China, TibetTectonics - structure
DS2002-0756
2002
Jackson, J.Jackson, J.Strength of the continental lithosphere: time to abandon the jelly sandwich?Gsa Today, Sept. pp. 4-9.India, China, TibetTectonics, geodynamics, lithosphere
DS2002-1033
2002
Jackson, J.McKenzie, D., Jackson, J.Conditions for flow in the continental crustTectonics, Vol. 21, No. 6, 10.1029/2001TC001394MantleTectonics, Heat flow
DS200512-0470
2005
Jackson, J.Jackson, J.Mountain roots and the survival of cratons.Astronomy and Geophysics, Vol. 46, 2, pp. 2.33-2.36.MantleCraton
DS200512-0705
2005
Jackson, J.McKenzie, D., Jackson, J., Priestley, K.Thermal structure of oceanic and continental lithosphere.Earth and Planetary Science Letters, Vol. 233, 3-4, May 15, pp. 337-349.Mantle, CanadaGeothermometry, mantle rheology, heat flow
DS200712-0292
2006
Jackson, J.Emmerson, B., Jackson, J., McKensie, D., Priestley, K.Seismicity, structure and rheology of the lithosphere in the Lake Baikal region.Geophysical Journal International, Vol. 167, 3, Dec. 1, pp. 1233-1272.RussiaGeophysics - seismics
DS200812-0513
2008
Jackson, J.Jackson, J., McKenzie, D., Priestley, K., Emmerson, B.New views on the structure and rheology of the lithosphere.Journal Geological Society of London, Vol. 165, 2, pp. 453-466.MantleTectonics
DS200812-0923
2008
Jackson, J.Priestly, K., Jackson, J., McKenzie, D.Lithospheric structure and deep earthquakes beneath India, the Himalaya and southern Tibet.Geophysical Journal International, Vol. 172, 1, pp. 345-362.IndiaGeophysics - seismics
DS201312-0044
2013
Jackson, J.Ayuso, R., Tucker, R., Peters, S., Foley, N., Jackson, J., Robinson, S., Bove, M.Preliminary radiogenic isotope study on the origin of the Khanneshin carbonatite complex, Helmand Province, Afghanistan.Journal of Geochemical Exploration, Vol. 133, pp. 6-14.AfghanistanCarbonatite
DS1984-0373
1984
Jackson, J.A.Jackson, J.A.Carbon: Pencil Lead and GemsEarth Scince., Vol. 37, No. 2, SUMMER PP. 16-18.GlobalDiamonds
DS1995-0119
1995
Jackson, J.A.Bates, R.L., Jackson, J.A.Glossary of geology on CD-ROMAmerican Geological Institute, GlobalBook -CD ROM., Glossary
DS2000-0606
2000
Jackson, J.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
DS2002-0757
2002
Jackson, J.A.Jackson, J.A.Using earthquakes for continental tectonic geologyInternational Geophysics Series, Vol. 81, A, pp. 491-504.MantleTectonics
DS201112-0219
2011
Jackson, J.A.Craig, T.J., Jackson, J.A., Priestley, K., McKenzie, D.Earthquake distribution patterns in Africa: their relationship to variations in lithospheric and geological structure, and their rheological implicationGeophysical Journal International, Vol. 185, 1, pp. 403-404.AfricaGeophysics - seismics
DS200712-0474
2007
Jackson, J.M.Jackson, J.M., Sturhahn, W., Lerche, M., Li, J.Electronic structure of iron in aluminous ferromagnesium silicate perovskite under lower mantle conditions.Frontiers in Mineral Sciences 2007, Joint Meeting of Mineralogical societies Held June 26-28, Cambridge, Abstract Volume p.146.MantlePerovskite
DS200712-0475
2007
Jackson, J.M.Jackson, J.M., Sturhahn, W., Lerche, M., Li, J.Electronic structure of iron in aluminous ferromagnesium silicate perovskite under lower mantle conditions.Frontiers in Mineral Sciences 2007, Joint Meeting of Mineralogical societies Held June 26-28, Cambridge, Abstract Volume p.146.MantlePerovskite
DS200912-0802
2008
Jackson, J.M.Wagner, L.B., Anderson, M.L., Jackson, J.M., Beck, S.L., Zandt,G.Seismic evidence for orthopyroxene enrichment in the continental lithosphere.Geology, Vol. 36, 12, Dec. pp. 936=938.MantleGeophysics - seismics
DS201312-0895
2013
Jackson, J.M.Sun, D., Helmberger, D.V., Jackson, J.M., Clayton, R.W.Rolling hills on the core-mantle boundary.Earth and Planetary Science Letters, Vol. 361, pp. 333-342.MantleCMB - structure
DS201606-1118
2016
Jackson, J.M.Solomatova, N.V., Jackson, J.M., Sturhahn, W., Wicks, J.K., Zhao, J., Toellner, T.S., Kalkan, B., Steinhardt, W.M.Equation of state and spin crossover of ( Mg,Fe)O at high pressure, with implications for explaining topographic relief at the core mantle boundary.American Mineralogist, Vol. 101, 5, pp. 1084-1093.MantleCore, mantle boundary
DS201709-2071
2017
Jackson, J.M.Wicks, J.K., Jackson, J.M., Struhahn, W., Zhang, D.Sound velocity and sensity of magnesiowustites: implications for ultralow velocity zone topography.Geophysics Research Letters, Vol. 44, 5, pp. 2148-2158.Mantlegeophysics - seismics

Abstract: We explore the effect of Mg/Fe substitution on the sound velocities of iron-rich (Mg1 - xFex)O, where x = 0.84, 0.94, and 1.0. Sound velocities were determined using nuclear resonance inelastic X-ray scattering as a function of pressure, approaching those of the lowermost mantle. The systematics of cation substitution in the Fe-rich limit has the potential to play an important role in the interpretation of seismic observations of the core-mantle boundary. By determining a relationship between sound velocity, density, and composition of (Mg,Fe)O, this study explores the potential constraints on ultralow-velocity zones at the core-mantle boundary.
DS201810-2313
2018
Jackson, J.M.Finkelstein, G.J., Jackson, J.M., Said, A., Alatas, A., Leu, B.M., Sturhahn, W., Toellner, T.S.Strongly anisotropic magnesiowustite in Earth's lower mantle. Journal of Geophysical Research Solid Earth, doi.org/10.1029/ 2017JB015349Mantlecore mantle boundary

Abstract: The juxtaposition of a liquid iron-dominant alloy against a mixture of silicate and oxide minerals at Earth's core-mantle boundary is associated with a wide range of complex seismological features. One category of observed structures is ultralow-velocity zones, which are thought to correspond to either aggregates of partially molten material or solid, iron-enriched assemblages. We measured the phonon dispersion relations of (Mg,Fe) O magnesiowüstite containing 76 mol % FeO, a candidate ultralow-velocity zone phase, at high pressures using high-energy resolution inelastic X-ray scattering. From these measurements, we find that magnesiowüstite becomes strongly elastically anisotropic with increasing pressure, potentially contributing to a significant proportion of seismic anisotropy detected near the base of the mantle.
DS201904-0771
2019
Jackson, J.M.Reali, R., Jackson, J.M., Van Orman, J., Bower, D.J., Carrez, P., Cordier, P.Modeling viscosity of ( Mg, Fe)O at lowermost mantle conditions.Physics of the Earth and Planetary Interiors, Vol. 287, pp. 65-75.Mantlecore-mantle boundary

Abstract: The viscosity of the lower mantle results from the rheological behavior of its two main constituent minerals, aluminous (Mg,Fe)SiO3 bridgmanite and (Mg,Fe)O ferropericlase. Understanding the transport properties of lower mantle aggregates is of primary importance in geophysics and it is a challenging task, due to the extreme time-varying conditions to which such aggregates are subjected. In particular, viscosity is a crucial transport property that can vary over several orders of magnitude. It thus has a first-order control on the structure and dynamics of the mantle. Here we focus on the creep behavior of (Mg,Fe)O at the bottom of the lower mantle, where the presence of thermo-chemical anomalies such as ultralow-velocity zones (ULVZ) may significantly alter the viscosity contrast characterizing this region. Two different iron concentrations of (Mg1-xFex)O are considered: one mirroring the average composition of ferropericlase throughout most of the lower mantle (x?=?0.20) and another representing a candidate magnesiowüstite component of ULVZs near the base of the mantle (x?=?0.84). The investigated pressure-temperature conditions span from 120?GPa and 2800?K, corresponding to the average geotherm at this depth, to core-mantle boundary conditions of 135?GPa and 3800?K. In this study, dislocation creep of (Mg,Fe)O is investigated by dislocation dynamics (DD) simulations, a modeling tool which considers the collective motion and interactions of dislocations. To model their behavior, a 2.5 dimensional dislocation dynamics approach is employed. Within this method, both glide and climb mechanisms can be taken into account, and the interplay of these features results in a steady-state condition. This allows the retrieval of the creep strain rates at different temperatures, pressures, applied stresses and iron concentrations across the (Mg,Fe)O solid solution, providing information on the viscosity for these materials. A particularly low viscosity is obtained for magnesiowüstite with respect to ferropericlase, the difference being around 10 orders of magnitude. Thus, the final section of this work is devoted to the assessment of the dynamic implications of such a weak phase within ULVZs, in terms of the viscosity contrast with respect to the surrounding lowermost mantle.
DS1975-0106
1975
Jackson, K.C.Howard, J.M., Jackson, K.C.Petrography of the Potash Sulfur Springs Intrusion, Garlandcounty, Arkansaw.Geological Society of America (GSA), Vol. 7, No. 2, PP. 173-174. (abstract.).United States, Gulf Coast, Arkansas, Garland CountyPetrography
DS1975-0604
1977
Jackson, K.C.Robison, E.C., Steele, K.F., Jackson, K.C.Geochemistry of Lamprophyric Rocks, Eastern Ouachita Mountains, Arkansaw.Geological Society of America (GSA), Vol. 9, No. 1, PP. 69-70.United States, Oklahoma, Gulf Coast, Arkansas, Garland CountyPetrology, Geochemistry
DS1975-0769
1978
Jackson, K.C.Jackson, K.C.Arkansaw Syenites, Fenitized Crustal Material?Geological Society of America (GSA), Vol. 10, No. 1, PP. 7-8.United States, Gulf Coast, Arkansas, Hot Spring County, Garland CountyMagnet Cove, Potash Sulfur Springs, Petrology
DS1975-1232
1979
Jackson, K.C.Steele, K.F., Jackson, K.C., Van buren, W.Geochemical Comparison of Arkansaw SyeniteGeological Society of America (GSA), Vol. 11, No. 2, P. 166. (abstract.).United States, Gulf Coast, Arkansas, Garland County, Hot Spring CountyMagnet Cove, Potash Sulfur Springs, Geochemistry
DS1975-0297
1976
Jackson, K.D.Jackson, K.D., Steele, K.F.New Dat a on Some Arkansaw Igneous RocksGeological Society of America (GSA), Vol. 8, No. 1, PP. 25-26. (abstract.).United States, Gulf Coast, Arkansas, Garland CountyGeochemistry
DS201603-0396
2016
Jackson, K.G.Long, M.D., Jackson, K.G., McNamara, J.F.SKS splitting beneath transportable array stations in eastern North America and the signature of past lithospheric deformation.Geochemistry, Geophysics, Geosystems: G3, Vol. 17, 1, pp. 2-15.United StatesGeophysics - seismics

Abstract: Seismic anisotropy in the upper mantle beneath continental interiors is generally complicated, with contributions from both the lithosphere and the asthenosphere. Previous studies of SKS splitting beneath the eastern United States have yielded evidence for complex and laterally variable anisotropy, but until the recent arrival of the USArray Transportable Array (TA) the station coverage has been sparse. Here we present SKS splitting measurements at TA stations in eastern North America and compare the measured fast directions with indicators such as absolute plate motion, surface geology, and magnetic lineations. We find few correlations between fast directions and absolute plate motion, except in the northeastern U.S. and southern Canada, where some stations exhibit variations in apparent splitting with backazimuth that would suggest multiple layers of anisotropy. A region of the southeastern U.S. is dominated by null SKS arrivals over a range of backazimuths, consistent with previous work. We document a pattern of fast directions parallel to the Appalachian mountain chain, suggesting a contribution from lithospheric deformation associated with Appalachian orogenesis. Overall, our measurements suggest that upper mantle anisotropy beneath the eastern United States is complex, with likely contributions from both asthenospheric and lithospheric anisotropy in many regions.
DS1950-0013
1950
Jackson, L.Belshaw, J.P., Jackson, L.Mining for Diamonds, Sapphires and Emeralds in Northern New south Wales.Armidale: New England University Reg. Res., No. 2, (UNPUBL.).AustraliaDiamond
DS1970-0940
1974
Jackson, M.Jackson, M.Gems, the Beautiful InvestmentDallas: R. Larry Kuehn Prod., 52P.GlobalKimberlite
DS1975-0751
1978
Jackson, M.Van De Graaff, W.J.E., Crowe, R.W.A., Bunting, J.A., Jackson, M.Relic Early Cainozoic Drainages in Arid Western AustraliaZeitschr. Geomorph., Vol. 21, No. 4, PP. 379-400.Australia, Western AustraliaDiamond, Geomorphology
DS1986-0392
1986
Jackson, M.Jackson, M., Van der Voo, R.A paleomagnetic estimate of the age and thermal history of the Kentland Indiana cryptoexplosion structureJournal of Geology, Vol. 94, No. 5, September pp. 713-724IndianaPaleomagnetics, Geophysics, Thermobarometry
DS1989-0967
1989
Jackson, M.McCabe, C., Jackson, M., Suffer, B.Regional patterns of magnetite authigenesis in the Appalachian basin:implications for the mechanism of late Paleozoic remagnetizationJournal of Geophys. Research, Vol. 94, No. B8, August 10, pp. 10, 429-10, 443AppalachiaGeophysics, Paleomagnetism
DS1991-0776
1991
Jackson, M.Jackson, M.Anisotropy of magnetic remanence- a brief review of mineralogical physical origins and geological applications, and comparison with susceptibilityanisotropPure and Applied Geophysics, Vol. 136, No. 1, May pp. 1-28GlobalReview, Anisotropy
DS1994-0814
1994
Jackson, M.Jackson, M.Mining on the edge of Yellowstone Park... extracted from an environmental management study.Crs Perspectives, No. 48, February pp. 2-15Montana, Ontario, Quebec, BrazilEnvironmental study, gold, Deposit -Mineral Hill
DS2003-0626
2003
Jackson, M.Iverson, N.R., Cohen, D., Hooyer, T.S., Fischer, U.H., Jackson, M., Moore, P.L.Effects of basal debris on glacier flowScience, No. 5629, July 4, pp. 81-83.GlobalGeomorphology
DS200412-0884
2003
Jackson, M.Iverson, N.R., Cohen, D., Hooyer, T.S., Fischer, U.H., Jackson, M., Moore, P.L., Lappegard, G., Kohler, J.Effects of basal debris on glacier flow.Science, No. 5629, July 4, pp. 81-83.TechnologyGeomorphology
DS200512-0286
2005
Jackson, M.Ferr, E.C., Tikoff, B., Jackson, M.The magnetic anistropy of mantle peridotites: examples from the Twin Sisters dunite, Washington.Tectonophysics, Vol. 398, 3-4, pp. 141-166.United States, WashingtonPeridotite - not specific to diamonds
DS200512-0289
2005
Jackson, M.Ferre, E.C., Tikoff, B., Jackson, M.The magnetic anisotropy of mantle peridotites: examples from the Twin Sisters dunite, Washington.Tectonophysics, Vol. 398, 3-4, April 13, pp. 141-166.United States, WashingtonGeophysics - AMS magnetometer, not specific to diamond
DS201312-0117
2013
Jackson, M.A.Cabral, R.A., Jackson, M.A., Rose-Kaga, E.F., Koga, K.T., Whitehouse, MJ., Antonelli, M.A., Farquhar, J., Day, J.M.D., Hauri, E.H.Anomalous sulphur isotopes in plume lavas reveal deep mantle storage of Archean crust.Nature, Vol. 496, April 25, pp. 490-493.Mantle, Cook IslandsSubduction
DS1991-1663
1991
Jackson, M.C.Stone, D., Kamineni, D.C., Jackson, M.C.Geology of the Atikokan areaGeological Association of Canada (GAC) Annual Meeting held Toronto May 1991, Guidebook, No. A7, 27pOntarioStructure, Steep Rock Group
DS1992-1483
1992
Jackson, M.C.Stone, D., Kamineni, D.C., Jackson, M.C.Precambrian geology of the Atikokan area, northwestern OntarioGeological Survey of Canada, Bulletin. No. 405, 106p. $ 23.95OntarioAtikokan area, Precambrian geology
DS201212-0687
2012
Jackson, M.D.Solano, J.M.S., Jackson, M.D., Sparks, R.S.J., Blundy, J.D., Annen, C.Melt segregation in deep crustal hot zones: a mechanism for chemical differentiation, crustal assimilation and the formation of evolved magmas.Journal of Petrology, Vol. 53, 10, pp. 1999-2026.MantleHotspots, magmatism
DS201807-1510
2018
Jackson, M.D.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.
DS201901-0042
2018
Jackson, M.D.Jackson, M.D., Blundy, J., Sparks, R.S.J. Chemical differentiation, cold storage and remobilization of magma in the Earth's crust.Nature, Vol. 564, pp. 405-409.Mantlemagmatism

Abstract: The formation, storage and chemical differentiation of magma in the Earth’s crust is of fundamental importance in igneous geology and volcanology. Recent data are challenging the high-melt-fraction ‘magma chamber’ paradigm that has underpinned models of crustal magmatism for over a century, suggesting instead that magma is normally stored in low-melt-fraction "mush reservoirs". A mush reservoir comprises a porous and permeable framework of closely packed crystals with melt present in the pore space1,10. However, many common features of crustal magmatism have not yet been explained by either the ‘chamber’ or ‘mush reservoir’ concepts. Here we show that reactive melt flow is a critical, but hitherto neglected, process in crustal mush reservoirs, caused by buoyant melt percolating upwards through, and reacting with, the crystals. Reactive melt flow in mush reservoirs produces the low-crystallinity, chemically differentiated (silicic) magmas that ascend to form shallower intrusions or erupt to the surface. These magmas can host much older crystals, stored at low and even sub-solidus temperatures, consistent with crystal chemistry data. Changes in local bulk composition caused by reactive melt flow, rather than large increases in temperature, produce the rapid increase in melt fraction that remobilizes these cool- or cold-stored crystals. Reactive flow can also produce bimodality in magma compositions sourced from mid- to lower-crustal reservoirs. Trace-element profiles generated by reactive flow are similar to those observed in a well studied reservoir now exposed at the surface. We propose that magma storage and differentiation primarily occurs by reactive melt flow in long-lived mush reservoirs, rather than by the commonly invoked process of fractional crystallization in magma chambers.
DS2000-0438
2000
Jackson, M.G.Jackson, M.G., Ihinger, P.D.Carbonatite expulsion from a lamprophyre: an integrated geochemical study of dike wall rock interaction.Geological Society of America (GSA) Abstracts, Vol. 32, No. 7, p.A-436.GlobalCarbonatite
DS200712-0862
2007
Jackson, M.G.Putirka, K.D., Perfit, M., Ryerson, F.J., Jackson, M.G.Ambient and excess mantle temperatures, olivine thermometry and active vs. passive upwelling.Chemical Geology, Vol. 241, 3-4, pp. 177-206.MantleGeothermometry
DS201112-0131
2011
Jackson, M.G.Cabral, R.A., Jackson, M.G., Rose-Koga, E.F., Fay, J.M.D., Shimizu, N.Volatile and trace element abundances in HIMU melt inclusions.Goldschmidt Conference 2011, abstract p.610.Polynesia, Cook IslandsWater, carbonatite
DS201112-0144
2011
Jackson, M.G.Carlson, R.W., Jackson, M.G.Implications of a non-chrondritic primitive mantle for chemical geodynamics.Goldschmidt Conference 2011, abstract p.624.Canada, Nunavut, Baffin IslandTrace element characteristics
DS201112-0469
2011
Jackson, M.G.Jackson, M.G., Carlson, R.W.A new starting point for the mantle's geochemical reservoirs.Goldschmidt Conference 2011, abstract p.1093.MantleGeochemistry
DS201511-1845
2015
Jackson, M.G.Jellinek, A.M., Jackson, M.G.Connections between bulk composition, geodynamics and habitability of Earth.Nature Geoscience, Vol. 8, pp. 587-593.MantleGeodynamics

Abstract: The bulk composition of the silicate part of Earth has long been linked to chondritic meteorites. Ordinary chondrites — the most abundant meteorite class — are thought to represent planetary building materials. However, a landmark discovery showed that the 142Nd/144Nd ratio of the accessible parts of the modern terrestrial mantle on Earth is greater than that of ordinary chondrites. If Earth was derived from these precursors, mass balance requires that a missing reservoir with 142Nd/144Nd lower than ordinary chondrites was isolated from the accessible mantle within 20 to 30 million years of accretion. This reservoir would host the equivalent of the modern continents' budget of radioactive heat-producing elements (uranium, thorium and potassium), yet has not been discovered. We argue that this reservoir could have been lost to space by ablation from early impactors. If so, Earth's radiogenic heat generation is between 18 and 45% lower than estimates based on a chondritic composition. Calculations of Earth's thermal history that incorporate such reduced radiogenic heating are consistent with a transition to the current plate tectonic mode in the past 2.5 billion years or so, a late onset of the dynamo and an evolving rate of volcanic outgassing consistent with Earth's long-term habitable climate. Reduced heat production compared with Venus and Mars could also explain aspects of the differences between the current climatic regimes of these planets and Earth.
DS201606-1110
2016
Jackson, M.G.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
DS201703-0409
2017
Jackson, M.G.Jackson, M.G., Konter, J.G., Becker, T.W.Primordial helium entrained by the hottest mantle plumes.Nature Geoscience, Jan. 7, 1p. PreviewEurope, IcelandHot spots

Abstract: Helium isotopes provide an important tool for tracing early-Earth, primordial reservoirs that have survived in the planet’s interior1, 2, 3. Volcanic hotspot lavas, like those erupted at Hawaii and Iceland, can host rare, high 3He/4He isotopic ratios (up to 50 times4 the present atmospheric ratio, Ra) compared to the lower 3He/4He ratios identified in mid-ocean-ridge basalts that form by melting the upper mantle (about 8Ra; ref. 5). A long-standing hypothesis maintains that the high-3He/4He domain resides in the deep mantle6, 7, 8, beneath the upper mantle sampled by mid-ocean-ridge basalts, and that buoyantly upwelling plumes from the deep mantle transport high-3He/4He material to the shallow mantle beneath plume-fed hotspots. One problem with this hypothesis is that, while some hotspots have 3He/4He values ranging from low to high, other hotspots exhibit only low 3He/4He ratios. Here we show that, among hotspots suggested to overlie mantle plumes9, 10, those with the highest maximum 3He/4He ratios have high hotspot buoyancy fluxes and overlie regions with seismic low-velocity anomalies in the upper mantle11, unlike plume-fed hotspots with only low maximum 3He/4He ratios. We interpret the relationships between 3He/4He values, hotspot buoyancy flux, and upper-mantle shear wave velocity to mean that hot plumes—which exhibit seismic low-velocity anomalies at depths of 200 kilometres—are more buoyant and entrain both high-3He/4He and low-3He/4He material. In contrast, cooler, less buoyant plumes do not entrain this high-3He/4He material. This can be explained if the high-3He/4He domain is denser than low-3He/4He mantle components hosted in plumes, and if high-3He/4He material is entrained from the deep mantle only by the hottest, most buoyant plumes12. Such a dense, deep-mantle high-3He/4He domain could remain isolated from the convecting mantle13, 14, which may help to explain the preservation of early Hadean (>4.5 billion years ago) geochemical anomalies in lavas sampling this reservoir1, 2, 3.
DS201808-1780
2018
Jackson, M.G.Putirka, K., Tao, Y., Hari, K.R., Perfit, M., Jackson, M.G., Arevalo, Jr. R.The mantle source of thermal plumes: trace and minor element & major oxides of primitive liquids ( and why olivine compositions don't matter).minoscam.org, doi.org/10.2138/am-2018-6192 59p.Mantleforsterite

Abstract: We estimate the mantle source compositions for mantle plumes, and by implication Earth’s lower mantle, by: (a) measuring trace (e.g, Sc, V, Cu) and minor (e.g., Ca, Mn, Ni) element concentrations of high forsterite olivine grains from several plume localities, (b) estimating the parent liquid compositions from which they crystallized, (c) calculating mantle potential temperatures and degrees of partial melting and (d) estimating trace element compositions of depleted and enriched mantle sources. Our sample set includes two continental flood basalt provinces (Emeishan and Deccan), a flood basalt that erupted in a continental rift setting (Baffin Island), our type example of a thermal mantle plume (Hawaii) and lavas from the Siqueiros Transform at the East Pacific Rise, which represent the mid-ocean ridge system. We also present olivine compositions for the peridotite xenoliths from Kilbourne Hole, New Mexico, USA, which are commonly used as primary and secondary analytical standards. We find that trace elements in lava-hosted olivine grains are too far removed from their mantle source to provided anything but greatly hindered views of such. Olivine compositions reflect not only evolving liquid compositions (including partial melting conditions and later fractionation), but also evolving Ol+liq partition coefficients, which mostly increase with decreasing T during crystallization. Mantle compositions, delimited by maximum forsterite contents and estimates of parental magmas (and experimentally determined partition coefficients) indicate that our selected plumes reflect some combination of (1) a depleted mantle source that is quite similar to that obtained by other methods, and (2) a variably enriched plume source that is more enriched than current estimates of pyrolite. The enriched plume mantle sources can be explained remarkably well as a mixture of subducted mid-ocean ridge basalt (MORB; Gale et al. 2013) and depleted MORB mantle (DM; Salters and Stracke 2004), with MORB:DM ratios of 1:5 to 1:4. These ratios are most sensitive to estimates of melt fraction where plume parental magmas are last equilibrated with their mantle source, but are nonetheless consistent across a wide range of chemically very different elements, and estimates of MORB and DM obtained by very different means. Baffin Island is of particular interest. Like prior studies, we verify a high mantle potential temperature (Tp) of 1630oC (compared to Tp = 1320-1420oC for MORB from Cottrell and Kelley 2011 for Ol of Fo89.3-91.4). The Baffin source is also within error the same as DM with respect to trace elements, although still isotopically distinct; Baffin appears to be sourced in something that is akin to DM that lies at the base of the mantle, where plumes acquire their excess heat. Thus while part of our analysis supports the concept of a "slab graveyard" at the bottom of the lower mantle (e.g., Wyession 1996), that cemetery is by no means ubiquitous at the CMB: subducted slabs are either unevenly interred, or efficiently excavated by later upwellings.
DS202008-1393
2020
Jackson, M.G.Giuliani, A., Jackson, M.G., Fitzpayne, A.The role of FOZO-PREMA in kimberlite genesis. Goldschmidt 2020, 1p. AbstractMantlekimberlite

Abstract: FOZO-PREMA is an ubiquitous component of oceanic basalts and was originally defined by the convergence of Sr- Nd-Pb isotope trends of ocean island basalts (OIBs) from individual island-seamount chains [1]. FOZO-PREMA is also widespread in juvenile continental magmas, which argue for a global relevance of this component irrespective of the tectonic settings. Early studies proposed that FOZO-PREMA could be a physically discrete reservoir derived from depletion of primitive mantle based on the combination of geochemically depleted 143Nd/144Nd combined with elevated 3He/4He ratios [2]. Conversely, later models showed that isotopic compositions spanning the FOZO-PREMA field can be obtained by mixing recycled oceanic crust and mantle material previously depleted by crust extraction [3]. Kimberlites can provide a new perspective on this debate because a recent study of the Nd and Hf isotope compositions of kimberlite through time shows that these magmas sample a deep, long-lived, homogeneous reservoir, which might contain remnants of early Earth differentiation processes [4]. We critically review the Sr, Nd and Hf isotope compositions of kimberlites that were emplaced from ~2.1 Ga. After screening kimberlite isotopic data for the effects of lithospheric contamination and secondary alteration, we show that kimberlites through time have been derived from a mantle source with FOZO-PREMA composition. This observation makes it unlikely that FOZO-PREMA derives from continuous mixing of depleted and recycled components because the composition of subducted lithologies, pressure and temperature conditions in subduction zones, and temperature and oxygen fugacity conditions of the convective mantle have changed throughout Earth history. We therefore conclude that FOZO-PREMA is a long-lived component of Earth’s mantle, which must have existed for at least the last 2.1 Ga, the wider implications of which will be discussed.
DS202102-0193
2020
Jackson, M.G.Giuliani, A., Jackson, M.G., Fitzpayne, A., Dalton, H.Remnants of early Earth differentiation in the deepest mantle-derived lavas. ( kimberlite source)PNAS, Vol. 118, 1 e201521118, 9p. PdfMantlekimberlite

Abstract: The noble gas isotope systematics of ocean island basalts suggest the existence of primordial mantle signatures in the deep mantle. Yet, the isotopic compositions of lithophile elements (Sr, Nd, Hf) in these lavas require derivation from a mantle source that is geochemically depleted by melt extraction rather than primitive. Here, this apparent contradiction is resolved by employing a compilation of the Sr, Nd, and Hf isotope composition of kimberlites—volcanic rocks that originate at great depth beneath continents. This compilation includes kimberlites as old as 2.06 billion years and shows that kimberlites do not derive from a primitive mantle source but sample the same geochemically depleted component (where geochemical depletion refers to ancient melt extraction) common to most oceanic island basalts, previously called PREMA (prevalent mantle) or FOZO (focal zone). Extrapolation of the Nd and Hf isotopic compositions of the kimberlite source to the age of Earth formation yields a 143Nd/144Nd-176Hf/177Hf composition within error of chondrite meteorites, which include the likely parent bodies of Earth. This supports a hypothesis where the source of kimberlites and ocean island basalts contains a long-lived component that formed by melt extraction from a domain with chondritic 143Nd/144Nd and 176Hf/177Hf shortly after Earth accretion. The geographic distribution of kimberlites containing the PREMA component suggests that these remnants of early Earth differentiation are located in large seismically anomalous regions corresponding to thermochemical piles above the core-mantle boundary. PREMA could have been stored in these structures for most of Earth’s history, partially shielded from convective homogenization.
DS202104-0578
2020
Jackson, M.G.Giuliani, A., Jackson, M.G., Fitzpayne, A., Dalton, H.Remnants of early Earth differentiation in the deepest mantle-derived lavas.Proceedings of the National Academy of Sciences PNAS, Vol. 118, 1 e201521118 9p. PdfMantlekimberlite

Abstract: The noble gas isotope systematics of ocean island basalts suggest the existence of primordial mantle signatures in the deep mantle. Yet, the isotopic compositions of lithophile elements (Sr, Nd, Hf) in these lavas require derivation from a mantle source that is geochemically depleted by melt extraction rather than primitive. Here, this apparent contradiction is resolved by employing a compilation of the Sr, Nd, and Hf isotope composition of kimberlites—volcanic rocks that originate at great depth beneath continents. This compilation includes kimberlites as old as 2.06 billion years and shows that kimberlites do not derive from a primitive mantle source but sample the same geochemically depleted component (where geochemical depletion refers to ancient melt extraction) common to most oceanic island basalts, previously called PREMA (prevalent mantle) or FOZO (focal zone). Extrapolation of the Nd and Hf isotopic compositions of the kimberlite source to the age of Earth formation yields a 143Nd/144Nd-176Hf/177Hf composition within error of chondrite meteorites, which include the likely parent bodies of Earth. This supports a hypothesis where the source of kimberlites and ocean island basalts contains a long-lived component that formed by melt extraction from a domain with chondritic 143Nd/144Nd and 176Hf/177Hf shortly after Earth accretion. The geographic distribution of kimberlites containing the PREMA component suggests that these remnants of early Earth differentiation are located in large seismically anomalous regions corresponding to thermochemical piles above the core-mantle boundary. PREMA could have been stored in these structures for most of Earth’s history, partially shielded from convective homogenization.
DS1970-0948
1974
Jackson, M.P.A.Kroner, A., Jackson, M.P.A.Geological Reconnaissance of the Coast between Luederitz And Marble Point Southwest Africa.Precambr. Res. Unit University Cape Town., Bulletin. No. 15, PP. 79-103.Southwest Africa, NamibiaGeology, Littoral Diamond Placers
DS1975-0298
1976
Jackson, M.P.A.Jackson, M.P.A.High Grade Metamorphism and Migmatization of the Namaqua Metamorphic Complex Around Aus in the Southern Namib Desert, South West Africa.Precamb. Res. Unit. University Cape Town., Bulletin. No. 18, 299P.Southwest Africa, NamibiaRegional Geology
DS1994-0815
1994
Jackson, M.P.A.Jackson, M.P.A., Vendeville, B.C.Regional extension as a geologic trigger for diapirisMGeological Society of America Bulletin, Vol. 106, No. 1, January pp. 57-73GlobalTectonics, Salt diapirs
DS200612-0629
2005
Jackson, M.P.A.Jackson, M.P.A., Hudec, M.R., Hegarty, K.A.The great West African Tertiary coastal uplift: fact or fiction? A perspective from the Angola Rift.Tectonics, Vol. 24, 6, TC6013. 10.1029/2005 TC1836Africa, West Africa, AngolaGeomorphology
DS1989-0076
1989
Jackson, P.D.Baria, R., Jackson, P.D., McCann, D.M.Further development of a high frequency seismic source for use inboreholesGeophysical Prospecting, Vol. 37, No. 1, January pp. 31-52GlobalGeophysics, Seismic - drillholes
DS1982-0293
1982
Jackson, P.L.Jackson, P.L.Appraisal of Land sat Lineaments As Faults in Western Kentucky. Final Report.National Technical Information Service DOE MC 16463-1324., 71P.GlobalMid-continent, Geophysics
DS1989-0655
1989
Jackson, R.D.Holm, R.G., Jackson, R.D., Yuan, B.Surface reflectance factor retrieval from thematic mapper dataRemote Sensing Environ, Vol. 27, pp. 47-57. Database # 17792GlobalRemote Sensing, TEM.
DS200912-0245
2009
Jackson, R.H.Gerlings, J., Funck, T., Jackson, R.H., Louden, K.E., Klingelhofer, F.Seismic evidence for plume derived volcanism during formation of the continental margin in southern Davis Strait and northern Labrador Sea.Geophysical Journal International, Vol. 176, 3, pp. 980-994.CanadaPlume
DS1970-0102
1970
Jackson, S.Jackson, S.The Great BarnatoLondon: Heinemann., 278P., ILLUS.South AfricaBiography, Kimberley
DS1998-0671
1998
Jackson, S.Jackson, S., Davies, R.Trace elements in the carbon of your choice by LAM ICP MSGemoc 1998 Annual Report, p. 28. abstractMantleDiamond inclusions
DS1998-1156
1998
Jackson, S.Petibon, C.M., Kjarsgaard, B., Jenner, G., Jackson, S.Liquidus phase relationships of a silicate bearing natro carbonatite from Oldoinyo Lengai at 20, 100 Mpa.Journal of Petrology, Vol. 39, No. 11-12, Nov-Dec. pp. 2137-51.TanzaniaCarbonatite, Deposit - Oldoinyo Lengai
DS2001-0517
2001
Jackson, S.Jackson, S., Davies, R., Griffin, B.Diamond fingerprints - for science and peaceGemoc Annual Report 2000, p. 23.GlobalMicroprobe analysis, Conflict diamonds
DS2003-1151
2003
Jackson, S.Rege, S., Davies, R.M., Griffin, W.L., Jackson, S., O'Reilly, S.Y.Trace element analysis of diamonds by LAM ICPMS: preliminary results8 Ikc Www.venuewest.com/8ikc/program.htm, Session 3, AbstractRussia, Siberia, Australia, Brazil, Northwest TerritoriesDiamonds - database 115, Geochemistry
DS200412-1648
2003
Jackson, S.Rege, S., Davies, R.M., Griffin, W.L., Jackson, S., O'Reilly, S.Y.Trace element analysis of diamonds by LAM ICPMS: preliminary results.8 IKC Program, Session 3, AbstractRussia, Siberia, AustraliaDiamonds - database 115 Geochemistry
DS201012-0476
2010
Jackson, S.Mather, K.A., Pearson, D.G., Kjarsgaard, B.A., Jackson, S.Understanding the lithosphere beneath Arctic Canada - an example from the N. Slave craton.38th. Geoscience Forum Northwest Territories, Abstract p. 65.Canada, Northwest TerritoriesDeposit - Artemisia
DS201012-0632
2010
Jackson, S.Robles-Cruz, S.E., Escayola, M., Melgarejo, J.C., Watangua, M., Gali, S., Goncalves, O.A., Jackson, S.Disclosed dat a from mantle xenoliths of Angolan kimberlites based on LA-ICP-MS analyses. Catoca and Cucumbi-79International Mineralogical Association meeting August Budapest, abstract p. 553.Africa, AngolaPetrology
DS201212-0318
2012
Jackson, S.Hunt, L.,Stachel, T., Pearson, D.G., Jackson, S., McLean, H., Kjarsgaard, B.The origin of websterites at Diavik diamondmine, Canada, and the realationship to diamond growth.10th. International Kimberlite Conference Feb. 6-11, Bangalore India, AbstractCanada, Northwest TerritoriesDeposit - Diavik
DS201212-0590
2012
Jackson, S.Robles-Cruz, S.E., Escayola, M., Jackson, S., Gali, S., Pervov, S., Watanga, M., Goncalves, A., Melgarejo, J.C.U-Pb SHRIMP geochronology of zircon from the Catoca kimberlite, Angola: implications for diamond exploration.Chemical Geology, Vol. 310-311, pp. 137-147.Africa, AngolaDeposit - Catoca
DS201810-2342
2018
Jackson, S.Lawley, C., Kjarsgaard, B., Jackson, S., Yang, Z., Petts, D., Roots, E.Trace metal and isotopic depth profiles through the Abitibi. Kirkland Lake kimberlite field.Lithos, Vol. 314-315, pp. 520-533.Canada, Ontariodeposit - Kirkland Lake

Abstract: Geophysical imaging of trans-lithospheric structures provide a spatial link between ore deposits in the crust and the underlying cratonic mantle. However, the deep lithosphere's role in ore deposit genesis remains poorly understood because remotely acquired datasets do not provide any direct constraints on the behaviour of ore elements within these mantle-roots. The abundance and behaviour of ore elements governs the metallic endowment of the cratonic mantle and the economic potential of mantle-derived magmas. Herein we present in situ electron probe microanalysis (EPMA) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) geochemical datasets for clinopyroxene and olivine mantle xenocrysts from the Jurassic Kirkland Lake kimberlite field, Abitibi greenstone belt, Canada. We specifically focus on unconventional trace elements, including ore elements with chalcophile and/or siderophile affinities (Ag-As-Au-Bi-Cu-Mo-Pb-Pt-Pd-Sb-Se-Sn-Te-W-Zn). Robust principal component analysis suggests that low-T, large-ion lithophile element alteration (Ba-Sr), which likely occurred during kimberlite emplacement, represents the largest source of variance for the xenocryst dataset. PT-dependent element partitioning during sub-solidus equilibration represents the second most important control on olivine and clinopyroxene chemistry. We demonstrate that least-altered, high-PT mantle silicates are, in fact, a significant mineral host for a range of ore elements (Cu-Zn ± Ag ± As ± Se ± Sn ± Mo) within equilibrated, garnet peridotite at depth (70-190 km). Statistical analysis of the raw, individual mass sweeps for each LA-ICP-MS signal suggest that the most abundant ore elements (Cu-Zn) occur predominantly as PT-dependent substitution reactions with the dominant mineral-forming elements, rather than as inclusions. A subset of high-PT olivine (160-180 km) yields Fe-Ni-S-poor and Na (Au ± Pt ± Pd)-rich compositions, which may reflect metasomatism, sulphide segregation and trapping of precious metal-bearing fluids at the base of the lithosphere. These anomalous mantle fragments possibly represent the first, direct sampling of precious metal-modified mantle peridotite beneath the Abitibi. Mid-PT olivine xenocrysts (70-120 km), which yield Mg-rich and high field-strength element-poor compositions, document a highly melt-depleted segment of mantle peridotite coincident with and below a shallow-dipping, low-seismic-velocity anomaly and conductive feature of the Kirkland Lake mid-lithosphere at 70-100 km. We speculate that the trace element signature of mid-PT xenocrysts documents the re-distribution of high-charge and incompatible elements from refractory garnet peridotite to phlogopite- and/or amphibole-bearing peridotite with conductive metasomatic up-flow zones. The rapid, sub-solidus diffusion of elements at high-T suggest that these processes likely occurred during, and/or immediately preceding, kimberlite volcanism. New in situ Pb isotope analyses of clinopyroxene xenocrysts sampled from metasomatized, low-Al garnet peridotite, however, also document ancient metasomatic events that likely pre-date Jurassic kimberlitic volcanism by at least one billion years.
DS1994-0816
1994
Jackson, S.A.Jackson, S.A.Diamond exploration in North America: status report January 1994Preprint of talk given at Dregs Meeting Feb. 1994., 1p text and 2 maps.United States, CanadaNews item
DS1992-0762
1992
Jackson, S.E.Jackson, S.E., et al.The application of laser-ablation microprobe - inductively coupled plasma-mass spectrometry (LAM-ICP-MS) to in situ trace element determinationsCanadian Mineralogist, Vol. 30, Pt. 4, December, pp. 1049-1064GlobalSpectrometry, Overview and examples in specific minerals
DS1992-0763
1992
Jackson, S.E.Jackson, S.E., et al.The application of laser-ablation microprobe -inductively coupled plasma-mass spectrometry (LAM-ICP-MS) to in situ trace element determinationsCanadian Mineralogist, Vol. 30, Pt. 4, December pp. 1049-1064GlobalSpectrometry, Overview -uses garnet not specific to diamond interests
DS1993-0924
1993
Jackson, S.E.Longerich, H.P., Jackson, S.E., Fryer, B.J., Strong, D.F.The laser ablation microprobe-inductively coupled plasma-massspectrometerGeoscience Canada, Vol. 20, No. 1, March pp. 21-25GlobalSpectrometry, Exploration techniques
DS1996-0460
1996
Jackson, S.E.Foley, S.F., Jackson, S.E., Jenner, G.A.Trace element partition coefficients for clinopyroxene and phlogopite in an alkaline lamprophyre from NewfoundlandGeochimica et Cosmochimica Acta, Vol. 60, No. 4, Feb. 1, pp. 629-638.NewfoundlandLamprophyre, Microscopy
DS1997-0904
1997
Jackson, S.E.Petibon, C.M., Jenner, G.A., Jackson, S.E., Kjarsgaard, B.Petrogenesis of Oldoinyo Lengai carbonatites: constraints from trace element partition coefficients.Geological Association of Canada (GAC) Abstracts, TanzaniaCarbonatite, Deposit - Oldoinyo Lengai
DS200412-0034
2004
Jackson, S.E.Andersen, T., Griffin, W.L., Jackson, S.E., Knudsen, T.L., Pearson, N.J.Mid-Proterozoic magmatic arc evolution at the southwest margin of the Baltic Shield.Lithos, Vol. 73, 3-4, April pp. 289-318.Europe, Norway, Baltic ShieldMagmatism, Laser ablation, geochronology
DS200612-0501
2006
Jackson, S.E.Griffin, W.L., Rege, S., O'Reilly, S.Y., Jackson, S.E., Pearson, N.J., Zedgenizov, D., Kurat, G.Trace element patterns of diamond: toward a unified genetic model.Geochimica et Cosmochimica Acta, Vol. 70, 18, p. 218. abstract only.TechnologyDiamond genesis geochemistry
DS200612-1528
2006
Jackson, S.E.Wieland, P.R., Beyer, E., Jackson, S.E., Pearson, N.J., O'Reilly, S.Y.Evaluation of a method of the separation of Ni in geological samples.Geochimica et Cosmochimica Acta, Vol. 70, 18, p. 19 abstract only.TechnologyGeochemistry - nickel
DS200812-0829
2008
Jackson, S.E.O'Reilly, S.Y., Griffin, W.L., Pearson, N.J., Jackson, S.E., Belousova, E.A., Alard, O., Saeed, A.Taking the pulse of the Earth: linking crustal and mantle events.Australian Journal of Earth Sciences, Vol. 55, pp. 983-995.MantleGeochronology
DS200812-0945
2008
Jackson, S.E.Rege, S., Griffin, W.L., Kurat, G., Jackson, S.E., Pearson, N.J., OReilly, S.Y.Trace element geochemistry of diamondite: crystallization of diamond from kimberlite carbonatite melts.Lithos, Vol. 106, 1-2, pp. 39-54.TechnologyDiamondite
DS201112-0862
2011
Jackson, S.E.Riches, A.J.V., Pearson, D.G., Kjarsgaard, B.A., Jackson, S.E., Stachel, T., Armstrong, J.P.Deep lithosphere beneath the Rae Craton: peridotite xenoliths from Repulse Bay, Nunavut.Yellowknife Geoscience Forum Abstracts for 2011, abstract p. 74-75.Canada, Nunavut, Victoria Island, Parry PeninsulaMineralogy
DS201212-0585
2012
Jackson, S.E.Riches, A.J.V., Pearson, D.G., Stern, R.A., Ickert, R.B., Kjarsgaard, B.A., Jackson, S.E., Ishikawa, A.Multi-stage metasomatism of a Roberts Victor eclogite linked to the formation and destruction of diamond.10th. International Kimberlite Conference Feb. 6-11, Bangalore India, AbstractAfrica, South AfricaDeposit - Roberts Victor
DS201412-0315
2014
Jackson, S.E.Griffin, W.L., Pearson, N.J., Andersen, T., Jackson, S.E., O'Reilly, S.Y., Zhang, M.Sources of cratonic metasomatic fluids: In-situ LA-MC-ICPMS analysis of Sr, Nd and Pb isotopes in Lima from the Jagersfontein kimberlite.American Journal of Science, Vol. 314, pp. 435-461.Africa, South AfricaDeposit - Jagersfontein
DS201511-1847
2015
Jackson, S.E.Julian, B.R., Foulger, G.R., Hatfield, O., Jackson, S.E., Simpson, E., Einbeck, J., Moore, A.Hotspots in hindsight. Mentions kimberlitesGeological Society of America Special Paper, No. 514, pp. SPE514-08.MantleHotspots

Abstract: Thorne et al. (2004), Torsvik et al. (2010; 2006) and Burke et al. (2008) have suggested that the locations of melting anomalies ("hot spots") and the original locations of large igneous provinces ("LIPs") and kimberlite pipes, lie preferentially above the margins of two "large lower-mantle shear velocity provinces", or LLSVPs, near the bottom of the mantle, and that the geographical correlations have high confidence levels (> 99.9999%) (Burke et al., 2008, Fig. 5). They conclude that the LLSVP margins are "Plume-Generation Zones", and that deep-mantle plumes cause hot spots, LIPs, and kimberlites. This conclusion raises questions about what physical processes could be responsible, because, for example, the LLSVPs are apparently dense and not abnormally hot (Trampert et al., 2004). The supposed LIP-hot spot-LLSVP correlations probably are examples of the "Hindsight Heresy" (Acton, 1959), of performing a statistical test using the same data sample that led to the initial formulation of a hypothesis. In this process, an analyst will consider and reject many competing hypotheses, but will not adjust statistical assessments correspondingly. Furthermore, an analyst will test extreme deviations of the data, , but not take this fact into account. "Hindsight heresy" errors are particularly problematical in Earth science, where it often is impossible to conduct controlled experiments. For random locations on the globe, the number of points within a specified distance of a given curve follows a cumulative binomial distribution. We use this fact to test the statistical significance of the observed hot spot-LLSVP correlation using several hot-spot catalogs and mantle models. The results indicate that the actual confidence levels of the correlations are two or three orders of magnitude smaller than claimed. The tests also show that hot spots correlate well with presumably shallowly rooted features such as spreading plate boundaries. Nevertheless, the correlations are significant at confidence levels in excess of 99%. But this is confidence that the null hypothesis of random coincidence is wrong. It is not confidence about what hypothesis is correct. The correlations probably are symptoms of as-yet-unidentified processes.
DS201601-0040
2015
Jackson, S.E.Riches, A.J.V., Ickert, R.B., Pearson, D.G., Stern, R.A., Jackson, S.E., Ishikawa, A.In situ oxygen isotope, major-, and trace element constraints on the metasomatic modification and crustal origin of a Diamondiferous eclogite from Roberts Victor, Kaapvaal Craton.Geochimica et Cosmochimica Acta, in press available, 45p.Africa, South AfricaDeposit - Roberts Victor
DS201603-0417
2016
Jackson, S.E.Riches, A.J.V., Ickert, R.B., Pearson, D.G., Stern, R.A., Jackson, S.E., Ishikawa, A., Kjarsgaard, B.A., Gurney, J.J.In situ oxygen-isotope, major, and trace element constraints on the metasomatic modification and crust origin of a Diamondiferous eclogite from Roberts Victor, Kaapvaal craton.Geochimica et Cosmochimica Acta, Vol. 174, pp. 345-359.Africa, South AfricaDeposit - Roberts Victor
DS201809-2054
2018
Jackson, S.E.Lawley, C.J.M., Kjarsgaard, B.A., Jackson, S.E., Yang, Z., Petts, D.C.Olivine and clinopyroxene mantle xenocryst geochemistry from the Kirkland Lake kimberlite field, Ontario.Geological Survey of Canada, Open File 8376, 9p.Canada, Ontariogeochemistry
DS201908-1773
2019
Jackson, S.E.Bussweiler, Y., Giuliani, A., Greig, A., Kjarsgaard, B.A., Petts, D., Jackson, S.E., Barrett, N., Luo, Y., Pearson, D.G.Trace element analysis of high-Mg olivine by LA-ICP-MS - characterization of natural olivine standards for matrix-matched calibration and application to mantle peridotites.Chemical Geology, Vol. 524, pp. 136-157.Mantleperidotite

Abstract: The trace element composition of olivine is becoming increasingly important in petrological studies due to the ubiquity of olivine in the Earth's upper mantle and in primitive magmatic rocks. The LA-ICP-MS method allows for the routine analysis of trace elements in olivine to sub-ppm levels, but a major drawback of this method is the lack of knowledge about possible downhole fractionation effects when non matrix-matched calibration is used. In this contribution, we show that matrix-matched (i.e., olivine-based) calibration is preferable for small laser spot sizes (<100?µm) due to significant laser-induced inter-element fractionation between olivine and commonly used silicate glass calibration materials, e.g., NIST SRM 612, GSD-1G and BHVO-2G. As a result, we present two Mg-rich natural olivine standards (355OL and SC-GB) that have been characterized by independent methods (EPMA, solution ICP-MS), and by LA-ICP-MS in four different laboratories. These natural olivines have been used 1) as primary standards for the matrix-matched calibration of olivine samples for most elements of interest (e.g., Li, Na, Al, P, Ca, Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Zn), and 2) as secondary standards to assess the accuracy of results. Comparison of olivine- and silicate glass-calibrated results for natural peridotitic olivine reveals that matrix-matched calibration is essential when using small laser spot sizes (<100?µm) in order to mitigate downhole fractionation effects for certain elements, especially Na, P, Mn, Co, Ni and Zn. If matrix-matched calibration is not feasible, we recommend that spot sizes of =100?µm, laser fluence of =4.0?J/cm2, and total laser shot counts of =250 (e.g., 5?Hz repetition rate for 50?s) are used in order to minimize fractionation effects between olivine and silicate glass calibration materials. We demonstrate the applicability of matrix-matched calibration on olivine from a suite of different mantle peridotite xenoliths sampled by kimberlites and alkali basalts from on-craton and off-craton localities.
DS202002-0202
2020
Jackson, S.E.Lawley, C.J.M., Pearson, G., Waterton, P., Zagorevski, A., Bedard, J.H., Jackson, S.E., Petts, D.C., Kjarsgaard, B.A., Zhang, S., Wright, D.Element and isotopic signature of re-fertilized mantle peridotite as determined by nanopower and olivine LA-ICPMS analyses.Chemical Geology, DOI:101016/ j.chemgeo.2020.119464Mantleperidotite

Abstract: The lithospheric mantle should be depleted in base- and precious-metals as these elements are transferred to the crust during partial melting. However, some melt-depleted mantle peridotites are enriched in these ore-forming elements. This may reflect re-fertilization of the mantle lithosphere and/or sequestering of these elements by residual mantle phase(s). Both processes remain poorly understood because of the low abundances of incompatible elements in peridotite and the nugget-like distribution of digestion-resistant mantle phases that pose analytical challenges for conventional geochemical methods. Herein we report new major and trace element concentrations for a suite of mantle peridotite and pyroxenite samples from the Late Permian to Middle Triassic Nahlin ophiolite (Cache Creek terrane, British Columbia, Canada) using Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICPMS) analysis of nanoparticulate powders and olivine. Compatible to moderately incompatible element concentrations suggest that Nahlin ophiolite peridotites represent residues after =20% melt extraction. Pyroxenite dykes and replacive dunite bands are folded and closely intercalated with residual harzburgite. These field relationships, coupled with the presence of intergranular base metal sulphide, clinopyroxene and Cr-spinel at the microscale, point to percolating melts that variably re-fertilized melt-depleted mantle peridotite. Radiogenic Pb (206Pb/204Pb?=?15.402-19.050; 207Pb/204Pb?=?15.127-15.633; 208Pb/204Pb?=?34.980-38.434; n?=?45) and Os (187Os/188Os 0.1143-0.5745; n?=?58) isotope compositions for a subset of melt-depleted peridotite samples further support metasomatic re-fertilization of these elements. Other ore-forming elements are also implicated in these metasomatic reactions because some melt-depleted peridotite samples are enriched relative to the primitive mantle, opposite to their expected behaviour during partial melting. New LA-ICPMS analysis of fresh olivine further demonstrates that a significant proportion of the highly incompatible element budget for the most melt-depleted rocks is either hosted by, and/or occurs as trapped inclusions within, the olivine-rich residues. Trapped phases from past melting and/or re-fertilization events are the preferred explanation for unradiogenic Pb isotope compositions and Paleozoic to Paleoproterozoic Re-depletion model ages, which predate the Nahlin ophiolite by over one billion years.
DS1994-0532
1994
Jackson, S.F.Foley, S.F., Jenner, G.A., Jackson, S.F., Fryer, B.J.Trace element partition coefficients phlogopite, clinopyroxene and matrixin alkaline lamprophyre.Mineralogical Magazine, Vol. 58A, pp. 280-281. AbstractNewfoundlandLamprophyre, Alkaline rocks -Notre Dame Bay
DS1990-0750
1990
Jackson, S.L.Jackson, S.L., Sutcliffe, R.H.Central Superior Province geology: evidence for an allochthonous, ensimatic, southern Abitibi greenstone beltCanadian Journal of Earth Sciences, Vol. 27, No. 4, April pp. 582-589OntarioTectonics -Superior, Abitibi greenstone belt
DS1991-0309
1991
Jackson, S.L.Corfu, F., Jackson, S.L., Sutcliffe, R.H.uranium-lead (U-Pb) (U-Pb) ages and tectonic significance of late Archean alkalic magmatism and nonmarine sedimentation: Timiskaming Group, southern Abitibi belt, OntarioCanadian Journal of Earth Sciences, Vol. 28, No. 4, April pp. 489-503OntarioTectonics, Geochronology
DS1994-0817
1994
Jackson, S.L.Jackson, S.L., Fyon, J.A., Corfu, F.Review of Archean supracrustal assemblages of the southern Abitibi Greenstone belt in Ontario, Canada: products of microplate interaction within alarge scale platePrecambrian Research, Vol. 65, No. 1-4, January pp. 183-206OntarioAbitibi greenstone belt, Tectonics
DS1992-0434
1992
Jackson, V.Epp, H., Jackson, V.Satellite remote sensing in the search for kimberlite pipes in the Northwest TerritoriesNorthwest Territories Geoscience Forum held November 25, 26th. 1992, poster, AbstractNorthwest TerritoriesGeophysics, Remote sensing
DS2003-0098
2003
Jackson, V.Bennett, V., Jackson, V., Rivers, T., Tubrett, M., Relf, C.Mapping lower crustal age domains utilizing LAM ICP MS U-Pb dating of inherited31st Yellowknife Geoscience Forum, p. 5. (abst.NunavutGeochronology, Tectonics, SRT
DS200412-0133
2003
Jackson, V.Bennett, V., Jackson, V., Rivers, T., Tubrett, M., Relf, C.Mapping lower crustal age domains utilizing LAM ICP MS U-Pb dating of inherited zircons: a new diamond exploration tool?31st Yellowknife Geoscience Forum, p. 5. (abst.Canada, NunavutGeochronology, Tectonics, SRT
DS201911-2551
2019
Jackson, V.Ootes, L., Sandemann, H., Cousens, B.L.,Luo, Y., Pearson, D.G., Jackson, V.Pyroxenite magma conduits ( ca 1.86 Ga) in Wopmay orogen and Slave craton: petrogenetic constrainst from whole rock and mineral chemistry.Lithos, in press available, 54p.Canada, Northwest Territorieslamprophyres
DS1994-0585
1994
Jackson, V.A.Gebert, J.S., Jackson, V.A.Preliminary compilation of the Point Lake Contwyoto Napultulik Kathawachaga Lakes area.Diand., EGS 1994-2, map.Northwest TerritoriesGeology
DS200612-0121
2006
Jackson, V.A.Bennett, V., Jackson, V.A., Rivers, T., Relf, C., Horan, P., Tubrett, M.Geology and U Pb geochronology of the Neoarchean Snare River terrane: tracking evolving tectonic regimes and crustal growth mechanisms.Canadian Journal of Earth Sciences, Vol. 42, 6, pp. 895-934.Canada, Northwest TerritoriesGeochronology
DS200912-0723
2009
Jackson, V.A.Spratt, J.E., Jones, A.G., Jackson, V.A., Collins, L., Avdeeva, A.Lithospheric geometry of the Wopmay orogen from a Slave Craton to Bear province magnetotelluric transect.Journal of Geophysical Research, Vol. 114, B1 B01101.CanadaGeophysics - magnetotellurics
DS201412-0636
2014
Jackson, V.A.Normandeau, P.X., Mcmartin, L., Jackson, V.A., Corriveau, L., Paquette, J.Kimberlite indicator minerals and gold grains in till from the Great Bear magmatic zone and Wopmay metamorphic zone, Northwest Territories, Canada.2014 Yellowknife Geoscience Forum Poster, p. 97, abstractCanada, Northwest TerritoriesKIMs in till
DS201707-1354
2017
Jackson, V.A.Ootes, L., Jackson, V.A., Davis, W.J., Bennett, V., Smar, L., Cousens, B.L.Parentage of Archean basement within a Paleoproterozoic orogen and implications for on-craton diamond preservation: Slave craton and Wopmay orogen, northwest Canada.Canadian Journal of Earth Sciences, Vol. 54, pp. 203-232.Canada, Northwest Territorieskimberlite

Abstract: The Wopmay orogen is a Paleoproterozoic accretionary belt preserved to the west of the Archean Slave craton, northwest Canada. Reworked Archean crystalline basement occurs in the orogen, and new bedrock mapping, U–Pb geochronology, and Sm–Nd isotopic data further substantiate a Slave craton parentage for this basement. Detrital zircon results from unconformably overlying Paleoproterozoic supracrustal rocks also support a Slave craton provenance. Rifting of the Slave margin began at ca. 2.02 Ga with a second rift phase constrained between ca. 1.92 and 1.89 Ga, resulting in thermal weakening of the Archean basement and allowing subsequent penetrative deformation during the Calderian orogeny (ca. 1.88–1.85 Ga). The boundary between the western Slave craton and the reworked Archean basement in the southern Wopmay orogen is interpreted as the rifted cratonic margin, which later acted as a rigid backstop during compressional deformation. Age-isotopic characteristics of plutonic phases track the extent and evolution of these processes that left penetratively deformed Archean basement, Paleoproterozoic cover, and plutons in the west, and “rigid” Archean Slave craton to the east. Diamond-bearing kimberlite occurs across the central and eastern parts of the Slave craton, but kimberlite (diamond bearing or not) has not been documented west of ~114°W. It is proposed that while the crust of the western Slave craton escaped thermal weakening, the mantle did not and was moved out of the diamond stability field. The Paleoproterozoic extension–convergence cycle preserved in the Wopmay orogen provides a reasonable explanation as to why the western Slave craton appears to be diamond sterile.
DS1994-0818
1994
Jackson, W.D.Jackson, W.D., Christiansen, G.International strategic minerals inventory summar report -rare earthoxidesUnited States Geological Survey (USGS) Circ, No. 930-N, 70pUnited States, GlobalEconomics, Rare earths
DS202108-1302
2021
Jacob, B.Pamato, M.G., Novella, D., Jacob, B., Oliveira, B., Pearson, D.G.Petrogenetic sulfide inclusions in diamonds date the diamond formation event using Re-Os isotopes.Geology, Vol. 49, pp. 941-945.Canada, Ontario, Nunavutdeposit - Victor, Jericho

Abstract: Sulfides are the most abundant inclusions in diamonds and a key tool for dating diamond formation via Re-Os isotopic analyses. The manner in which fluids invade the continental lithospheric mantle and the time scale at which they equilibrate with preexisting (protogenetic) sulfides are poorly understood yet essential factors to understanding diamond formation and the validity of isotopic ages. We investigated a suite of sulfide-bearing diamonds from two Canadian cratons to test the robustness of Re-Os in sulfide for dating diamond formation. Single crystal X-ray diffraction (XRD) allowed determination of the original monosulfide solid-solution (Mss) composition stable in the mantle, indicating subsolidus conditions of encapsulation, and providing crystallographic evidence supporting a protogenetic origin of the inclusions. The results, coupled with a diffusion model, indicate Re-Os isotope equilibration is sufficiently fast in sulfide inclusions with typical grain size, at mantle temperatures, for the system to be reset by the diamond-forming event. This confirms that even if protogenetic, the Re-Os isochrons defined by these minerals likely reflect the ages of diamond formation, and this result highlights the power of this system to date the timing of fluid migration in mantle lithosphere.
DS1991-0777
1991
Jacob, D.Jacob, D., Jagoutz, E., Sobolev, N.V.A diamond graphite bearing eclogitic xenolith from Roberts Victor-indication for petrogenesis from lead, neodymium, and Sr isotopesProceedings of Fifth International Kimberlite Conference held Araxa June 1991, Servico Geologico do Brasil (CPRM) Special, pp. 190-192South AfricaGeochronology, Geochemistry
DS1993-0728
1993
Jacob, D.Jacob, D., Jagoutz, E., et al.Diamondiferous eclogites from Siberia: ancient oceanic crustAmerican Geophysical Union, EOS, supplement Abstract Volume, October, Vol. 74, No. 43, October 26, abstract p. 637.Russia, SiberiaEclogite
DS1994-0819
1994
Jacob, D.Jacob, D., Jagoutz, E.A diamond graphite bearing eclogitic xenoliths from Roberts Victor (SouthAfrica) -indication for petrogenesis from lead neodymium and Sr isotopes.Proceedings of Fifth International Kimberlite Conference, Vol. 1, pp. 304-317.South AfricaGeochronology, Deposit -Roberts Victor
DS1994-0820
1994
Jacob, D.Jacob, D., Jagoutz, E., Lowry, D., Mattey, D., KudrjavtsevaDiamondiferous eclogites from Siberia: remnants of Archean oceanic crustGeochimica et Cosmochimica Acta, Vol. 58, 23, pp. 5191-207.Russia, SiberiaEclogites, Deposit -Udachnaya
DS1998-0672
1998
Jacob, D.Jacob, D., Jagoutz, E., Zinngrebe, E., Snyder, TaylorComment and reply on the origins of Yakutian eclogite xenolithsJournal of Petrology, Vol. 39, No. 8, Aug. 1, pp. 1527-1539.Russia, YakutiaEclogites, Diamond genesis
DS1998-1648
1998
Jacob, D.Zinngrebe, E., Jacob, D., Ramos, Z., Smith, C.B.A model for eclogite peridotite interactions: activity driven with evidence from Zero eclogiteMineralogical Magazine, Goldschmidt abstract, Vol. 62A, p. 1705-6.South AfricaSubduction, eclogite, Deposit - Zero
DS200412-0563
2004
Jacob, D.Foley, S., Vannucci, R., Jacob, D., Tiepolo, M.The geochemical signature and origin of Archean TTG gneisses: melting of amphibolite or eclogite?Lithos, ABSTRACTS only, Vol. 73, p. S38. abstractTechnologySubduction
DS200612-0630
2006
Jacob, D.Jacob, D., Resiberg, L., Yaxley, G.Processes of mantle refertilization and modification.Goldschmidt Conference 16th. Annual, S5-05 theme abstract 1/8p. goldschmidt2006.orgMantleCraton
DS201112-0433
2011
Jacob, D.Hettmann, K., Marks, M., Kressing, K., Zack, T., Wenzel, T., Rehkamper, M., Jacob, D., Markl, G.The geochemistry of thallium and its isotopes in a peralkaline magmatic system.Peralk-Carb 2011, workshop held Tubingen Germany June 16-18, PosterTechnologyMagmatism
DS201505-0246
2015
Jacob, D.Griffin, W.L., Gain, S.E.M., Toledo, V., O'Reilly, S.Y., Jacob, D., Pearson, N.J.Corundum, moissanite and super reducing conditions in the upper mantle beneath the lower ( southern) Galilee ( Israel).Israel Geological Society, 1p.posterEurope, IsraelMineralogy
DS201605-0848
2016
Jacob, D.Jacob, D.Insights into subcratonic lithosphere development from banded eclogite xenoliths.DCO Edmonton Diamond Workshop, June 8-10MantleXenoliths
DS201902-0257
2019
Jacob, D.Aulbach, S., Heaman, L.M., Jacob, D., Viljoen, K.S.Ages and sources of mantle eclogites: ID-TIMS and in situ MC-ICPMS Pb-Sr isotope systematics of clinopyroxene.Chemical Geology, Vol. 503, pp. 15-28.Africa, South Africa, Zimbabwe, Sierra Leonedeposit - Lace, Orapa, Koidu

Abstract: Strontium and Pb isotopic compositions of clinopyroxene (cpx) in selected samples from three well-characterised eclogite suites with oceanic crustal protoliths (Lace/Kaapvaal craton, Orapa/Zimbabwe craton and Koidu/West African craton) were acquired by high-precision isotope dilution thermal ionisation mass spectrometry (ID-TIMS) and in situ multicollector-laser ablation-inductively-coupled plasma mass spectrometry (MC-LA-ICPMS). The aims of this study are twofold: (1) assess their utility to obtain formation or resetting age constraints and identify elemental signatures that enhance the chances of successful age dating, and (2) to confirm the veracity and utility of results obtained by novel MC-LA-ICPMS techniques. Strontium-Pb isotope systematics of eclogitic cpx measured in this study are decoupled and may reflect addition of unsupported radiogenic Sr during seawater alteration or interaction with oceanic sediments in subduction mélanges, and/or disturbance due to mantle metasomatism, to which the more incompatible Pb is more susceptible. Despite a complex history, subsets of samples yield meaningful model dates. Clinopyroxene fractions from Lace with high Pb contents (3-6?ppm), unradiogenic Pb isotopic compositions (206Pb/204Pb?=?13.57-13.52) and low 238U/204Pb (1.0-1.5) give single-stage model Pb dates of 2.90-2.84?Ga. In contrast, samples from Orapa plot to the right of the Geochron and do not yield meaningful Pb model ages. However, these data do define secondary isochrons that can be modelled to yield minimum age constraints on major events affecting the cratonic lithosphere. Within the uncertainties, the resultant 2.18?±?0.45?Ga age obtained for Koidu eclogites reflect disturbance of the Pb isotope system due to subduction beneath the craton linked to the Eburnean orogeny, while they retained their unradiogenic 87Sr/86Sr (0.7016). Similarly, the age for samples from Orapa (2.20?±?0.54?Ga) is interpreted as an overprint age related to Palaeoproterozoic accretion at the western craton margin. Gabbroic eclogites (Eu/Eu*?>?1) with plagioclase-rich protoliths having low time-integrated Rb/Sr and U/Pb retain the least radiogenic Sr and, in part, Pb. High model µ (9.0 to 9.1) for several eclogites from Lace with elevated LREE, Th and Pb abundances reflects ca. 3.0?Ga addition of a sedimentary component, possibly derived from reworking of a high-µ basaltic protocrust, as observed on other cratons. We suggest that sample targeting can be usefully guided by fast-throughput in situ LA-ICPMS techniques, which largely yield results identical to ID-TIMS, albeit at lower precision, and which can further help identify kimberlite contamination in the mineral separates used for solution work.
DS1992-0764
1992
Jacob, D.E.Jacob, D.E., Jagutz, E.Diamondiferous eclogites and mixing of mantle componentsEos Transactions, Vol. 73, No. 14, April 7, supplement abstracts p. 324South AfricaGeochronology, Roberts Victor
DS1993-0729
1993
Jacob, D.E.Jacob, D.E., Jagoutz, E., Sobolev, N.V.Isotopic systematics of subcalcic garnets from SiberiaEos, Transactions, American Geophysical Union, Vol. 74, No. 16, April 20, supplement abstract p. 320Russia, SiberiaGeochemistry -garnets, Geochronology
DS1994-0821
1994
Jacob, D.E.Jacob, D.E., Jagoutz, E., Lowry, D., et al.Diamondiferous eclogites from Udachnaya: a subducted component in the Siberian upper mantle.Mineralogical Magazine, Vol. 58A, pp. 448-449. AbstractRussia, SiberiaEclogites, diamond genesis, Deposit -Udachnaya
DS1995-0862
1995
Jacob, D.E.Jacob, D.E., Jagoutz, E., Sobolev, N.V., Sorowka, A.Isotopic analysis ( Samarium/neodymium, Rubidium-Strontium and Uranium/lead) of single subcalcic garnet grains from Yakutian kimberlites.Proceedings of the Sixth International Kimberlite Conference Abstracts, pp. 257-259.Russia, YakutiaGeochemistry, isotopes, Geochronology -garnets
DS1998-0673
1998
Jacob, D.E.Jacob, D.E., Foley, S.F.Evidence for Archean ocean crust with Island Arc signature from diamondiferous eclogite xenoliths.7th International Kimberlite Conference Abstract, pp. 358-60.South Africa, Russia, YakutiaXenoliths, Deposit - Udachnaya, Finsch, Jagersfontein, Kaalvallei
DS1998-0674
1998
Jacob, D.E.Jacob, D.E., Jagoutz, E., Sobolev, N.V.Neodynium and strontium isotopic measurements on single subcalcic garnet grains from Yakutian kimberlites.Neues Jahrbuch fnr Mineralogie Abh., No. 172, pp. 357-379.Russia, YakutiaGeochronology
DS1998-0675
1998
Jacob, D.E.Jacob, D.E., Kjarsgaard, B., Horn, I.Trace element concentrations by laser ablation ICP-MS in subcalcic garnets from Saskatchewan and Somerset Is.7th International Kimberlite Conference Abstract, pp. 361-63.Saskatchewan, Somerset IslandGeochemistry, Deposit - Fort a la Corne
DS1998-0676
1998
Jacob, D.E.Jacob, D.E., Mattey, D.P.Geochemistry of layered kyanite bearing eclogites froim the Roberts Victormine.7th International Kimberlite Conference Abstract, pp. 364-5.South AfricaGeochemistry - garnets, Deposit - Roberts Victor
DS1999-0328
1999
Jacob, D.E.Jacob, D.E., Foley, S.F.Evidence for Archean ocean crust with low high field strength element signature - Diamondiferous eclogiticLithos, Vol. 48, No. 1-4, Sept. pp. 317-GlobalEclogites, xenoliths, Mineral chemistry
DS2001-0518
2001
Jacob, D.E.Jacob, D.E.Evidence for the geochemistry and petrology of Late Archean oceanic crust from mantle eclogite xenoliths.Geological Association of Canada (GAC) Annual Meeting Abstracts, Vol. 26, p.70, abstract.GlobalEclogites
DS2003-0415
2003
Jacob, D.E.Foley, S.F., Buhre, S., Jacob, D.E.Evolution of the Archean crust by delamination and shallow subductionNature, No. 6920, Jan 16, pp. 249-51.MantleSubduction
DS2003-0416
2003
Jacob, D.E.Foley, S.F., Buhre, S., Jacob, D.E., Rehfeldt, T.Pyroxenite and dunite xenoliths as metamorphosed cumulates from the Archean lower8ikc, Www.venuewest.com/8ikc/program.htm, Session 2, POSTER abstractGlobalEclogites and Diamonds
DS2003-0630
2003
Jacob, D.E.Jacob, D.E.The origin of eclogite xenoliths from the Earth's mantle8 Ikc Www.venuewest.com/8ikc/program.htm, Session 2, AbstractGlobalEclogites, diamonds - petrogenetic, Review
DS2003-0631
2003
Jacob, D.E.Jacob, D.E., Fung, A., Jagoutz, E., Pearson, D.G.Petrology and geochemistry of eclogite xenoliths from the Ekati kimberlite area8ikc, Www.venuewest.com/8ikc/program.htm, Session 2, POSTER abstractNorthwest TerritoriesEclogites and Diamonds, Deposit - Ekati
DS2003-0632
2003
Jacob, D.E.Jacob, D.E., Schmickler, B., Schulze, D.J.Trace element geochemistry of coesite bearing eclogites from the Roberts VictorLithos, Vol. 71, 2-4, pp. 337-351.South AfricaGeochemistry - deposit
DS2003-1020
2003
Jacob, D.E.Nowell, G.M., Pearson, D.G., Jacob, D.E., Spetsius, S., Nixon, P.H., HaggertyThe origin of alkremites and related rocks: a Lu Hf Rb Sr and Sm Nd isotope study8ikc, Www.venuewest.com/8ikc/program.htm, Session 4, POSTER abstractRussia, YakutiaMantle geochemistry, Deposit - Udachnaya
DS200412-0888
2003
Jacob, D.E.Jacob, D.E.The origin of eclogite xenoliths from the Earth's mantle.8 IKC Program, Session 2, AbstractTechnologyEclogite, diamonds - petrogenetic Review
DS200412-0889
2004
Jacob, D.E.Jacob, D.E.Nature and origin of eclogite xenoliths from kimberlites.Lithos, Vol. 77, 1-4, Sept. pp. 295-316.Africa, South Africa, Sierra LeoneKuruman, Koidu, mineral chemistry, isotopes, mantle
DS200412-0890
2004
Jacob, D.E.Jacob, D.E., Kronz, A., Viljoen, K.S.Cohenite, native iron and troilite inclusions in garnets from polycrystalline diamond aggregates.Contributions to Mineralogy and Petrology, Vol. 146, 5, pp. 566-76.Africa, South AfricaDiamond inclusions
DS200412-0891
2003
Jacob, D.E.Jacob, D.E., Schmickler, B., Schulze, D.J.Trace element geochemistry of coesite bearing eclogites from the Roberts Victor kimberlite, Kaapvaal Craton.Lithos, Vol. 71, 2-4, pp. 337-351.Africa, South AfricaGeochemistry - deposit
DS200412-1754
2004
Jacob, D.E.Schmickler, B., Jacob, D.E., Foley, S.F.Eclogite xenoliths from the Kuruman kimberlites, South Africa: geochemical fingerprinting of deep subduction and cumulate procesLithos, Vol. 75, 1-2, July pp. 173-207.Africa, South AfricaSubduction, Zero, petrogenetic processes
DS200512-0471
2005
Jacob, D.E.Jacob, D.E., Bizimis, M., Salters, V.J.M.Lu Hf and geochemical systematics of recycled ancient oceanic crust: evidence from Roberts Victor eclogites.Contributions to Mineralogy and Petrology, Vol. 148, 6, pp. 707-720.Africa, South AfricaGeochemistry
DS200612-0403
2006
Jacob, D.E.Foley, S.F., Andronikov, A.V., Jacob, D.E., Melzer, S.Evidence from Antarctic mantle peridotite xenoliths for changes in mineralogy, geochemistry and geothermal gradients beneath a developing rift.Geochimica et Cosmochimica Acta, Vol. 70, 12, June pp. 3096-3120.AntarcticaGeothermometry
DS200612-0631
2006
Jacob, D.E.Jacob, D.E., Foley, S.F., Andonikov, A.V.Re-enrichment of cratonic lithospheric mantle beneath an evolving rift: mantle xenoliths from East Antarctica.Geochimica et Cosmochimica Acta, Vol. 70, 18, p. 285. abstract only.AntarcticaXenolith - geochemistry
DS200712-0883
2006
Jacob, D.E.Rehfeldt, T., Foley, S.F., Jacob, D.E.Restoration of premetasomatic protolith compositions in mantle xenoliths.Geochimica et Cosmochimica Acta, In press availableMantleMetasomatism
DS200712-0884
2007
Jacob, D.E.Rehfeldt, T., Foley, S.F., Jacob, D.E., Carlson, R.W.Characterizing Fe rich dunite xenoliths as cumulates of Phanerozoic and Archean flood basalt magmatism.Plates, Plumes, and Paradigms, 1p. abstract p. A827.Africa, South AfricaKimberley Cluster
DS200712-0885
2007
Jacob, D.E.Rehfeldt, T., Jacob, D.E., Carlson, R.W., Foley, S.F.Fe rich dunite xenoliths from South African kimberlites: cumulates from Karoo flood basalts.Journal of Petrology, Vol. 48, 7, pp. 1387-1409.Africa, South AfricaMineral chemistry
DS200812-0362
2008
Jacob, D.E.Foley, S.F., Jacob, D.E.Trace element and isotopic effects of mantle metasomatism by carbonatitic and alkaline silicate melts in the lower cratonic mantle lithosphere.9IKC.com, 3p. extended abstractMantleMelting
DS200812-0363
2008
Jacob, D.E.Foley, S.F., Yaxley, G.M., Rosenthal, A., Rapp, R.P., Jacob, D.E.Experimental melting of peridotites in the presence of CO2 and H2O at 40 - 60 kbar.9IKC.com, 3p. extended abstractTechnologyPeridotite - melting
DS200812-0948
2008
Jacob, D.E.Rehfeldt, T., Foley, S.F., Jacob, D.E., Carlson, R.W., Lowry, D.Contrasting types of metasomatism in dunite, wehrlite and websterite xenoliths from Kimberley, South Africa.Geochimica et Cosmochimica Acta, Vol. 73, 23, Dec. 1. pp. 5722-5756.Africa, South AfricaDeposit - Kimberley
DS200812-0949
2007
Jacob, D.E.Rehfeldt, T., Jacob, D.E., Carlson, R.W., Foley, S.F.Fe rich dunite xenoliths from South African kimberlites: cumulates from Karoo flood basalts.Journal of Petrology, Vol. 48, pp. 1387-1409.Africa, South AfricaXenoliths
DS200912-0081
2009
Jacob, D.E.Buhre, S., Jacob, D.E., Foley, S.F.Delayed continental crust formation on a hot Archean Earth.Goldschmidt Conference 2009, p. A171 Abstract.MantleMelting
DS200912-0608
2008
Jacob, D.E.Rahfeldt, T., Foley, S.F., Jacob, D.E., Carlson, R.W., Lowry, D.Contrasting types of metasomatism in dunite, wherlite and websterite xenoliths from Kimberley, South Africa.Geochimica et Cosmochimica Acta, Vol. 72, 5722-36.Africa, South AfricaDeposit - Kimberley
DS201012-0204
2010
Jacob, D.E.Foley, S.F., Jacob, D.E., O'Neill, H.St.C.Trace element variations in olivine phenocrysts from Ugand an potassic rocks as clues to the chemical characteristics of parental magmas.Contributions to Mineralogy and Petrology, In press available, 20p.Africa, UgandaGeochemistry - East African Rift
DS201012-0205
2009
Jacob, D.E.Foley, S.F., Yaxley, G.M., Rosenthal, A., Buhre, S., Kisseeva, E.S., Rapp, R.P., Jacob, D.E.The composition of near solidus melts of peridotite in the presence of CO2 and H2O between 40 and 60 kbar.Lithos, Vol. 112 S pp. 274-283.MantleMineral chemistry
DS201012-0243
2010
Jacob, D.E.Gonzaga, R.G., Lowry, D., Jacob, D.E., Le Roex, A., Schulze, D., Menzies, M.A.Eclogites and garnet pyroxenes: similarities and differences.Journal of Volcanology and Geothermal Research, Vol. 190, 1-2 pp. 235-247.TechnologyEclogite
DS201012-0244
2010
Jacob, D.E.Gonzaga, R.G., Menzies, M.A., Thirwala, M.F., Jacob, D.E., Le Roex, A.Eclogites and garnet pyroxenites: problems resolving provenance using Lu-Hf, Sm-Nd and Rb-Sr isotope systems.Journal of Petrology, Vol. 51, 1-2, pp. 513-535.MantleGeochronology
DS201012-0317
2010
Jacob, D.E.Jacob, D.E., Wirth, R., Enzmann, F., Kronz, A.Combined FIB/TEM and microcomputer tomography of polycrystalline diamond ( framesite) from Orapa, Botswana.International Mineralogical Association meeting August Budapest, abstract p. 178.Africa, BotswanaFramesite
DS201012-0621
2010
Jacob, D.E.Rehfeldt, T., Foley, S.F., Jacob, D.E., Pearson, D.G.Trace elements in mantle olivine and orthopyroxene from the North Atlantic and Kaapvaal Cratons.Goldschmidt 2010 abstracts, abstractAfrica, South Africa, EuropeGeochemistry
DS201112-0326
2011
Jacob, D.E.Foley, S.F., Jacob, D.E., O'Neill, H.St.C.Trace element variations in olivine phenocrysts from Ugand an potassic rocks as clues to the chemical characteristics of parental magma.Contributions to Mineralogy and Petrology, Vol, 167, 1, July pp. 1-20.Africa, UgandaAlkaline rocks, magmatism
DS201112-0470
2011
Jacob, D.E.Jacob, D.E., Wirth, R., Enzmann, F.Polycrystalline diamonds witness redox processes in the Earth's mantle.Goldschmidt Conference 2011, abstract p.1095.Africa, BotswanaDeposit - Orapa
DS201112-0471
2011
Jacob, D.E.Jacob, D.E., Wirth, R., Enzmann, F., Kronz, A., Schreiber, A.Nano-inclusion suite and high resolution micro-computed tomography of polycrystalline diamond (framesite) from Orapa, Botswana.Earth and Planetary Science Letters, Vol. 308, 3-4, pp. 307-316.Africa, BotswanaInclusions
DS201112-0472
2011
Jacob, D.E.Jacob, D.E., Wirth, R., Enzmann, F., Kronz, A., Schrieber, A.Nano-inclusion suite and high resolution micro-computed-tomography of polycrystalline diamond (framesite) from Orapa, Botswana.Earth and Planetary Science Letters, Vol. 308, 3-4, pp. 307-316.Africa, BotswanaDeposit - Orapa
DS201112-0924
2011
Jacob, D.E.Schilling, J., Marks, m.A.W., Wenzel, T., Vennenmann, T., Horvth, L., Tarassof, P., Jacob, D.E., Markl, G.The magmatic to hydrothermal evolution of the intrusive Mont Sainte Hilaire Complex: insights into the late stage evolution of peralkaline rocks.Journal of Petrology, Vol. 52, 11. pp. 2147-2185.Canada, QuebecAlkaline rocks, carbonatite
DS201312-0017
2013
Jacob, D.E.Ammannati, E., Foley, S.F., Avanzinelli, R., Jacob, D.E., Conticelli, S.Trace elements in olivine characterize the mantle source of subduction related potassic magmas.Goldschmidt 2013, AbstractMantleSubduction
DS201312-0271
2013
Jacob, D.E.Foley, S.F., Prelevic, D., Rehfeldt, T., Jacob, D.E.Minor and trace elements in olivines as probes into early igneous and mantle melting.Earth and Planetary Science Letters, Vol. 363, pp. 181-191.MantleMetasomatism
DS201312-0280
2013
Jacob, D.E.Fritschle, T., Prelevic, D., Foley, S.F., Jacob, D.E.Petrological characterization of the mantle source of Mediterranean lamproites: indications from major and trace elements of phlogopite.Chemical Geology, Vol. 353, pp. 267-279.Europe, SpainLamproite
DS201412-0086
2014
Jacob, D.E.Bussweiler, Y., Foley, S.F., Prelevic, D., Jacob, D.E., Pearson, D.G., Stachel, T.Olivine as a petrogenetic and exploration indicator in Lac de Gras kimberlites.2014 Yellowknife Geoscience Forum, p. 20, 21 abstractCanada, Northwest TerritoriesDeposit - Ekati
DS201412-0415
2014
Jacob, D.E.Jacob, D.E., Dobrrzhinetskaya, L., Wirth, R.New insight into polycrystalline diamond genesis from modern nanoanalytical techniques. Earth Science Reviews, Vol. 136, Sept. pp. 21-35.MantleDiamond, carbonado, UHP, subduction
DS201412-0870
2013
Jacob, D.E.Sommer, H., Wan,Y., Kroner, A., Xie, H., Jacob, D.E.Shrimp zircon ages and petrology of lower crustal granulite xenoliths from the Letseng-La-Terae kimberlite, Lesotho: further evidence for a Namaquanatal connection.South Africa Journal of Geology, Vol. 116, 2, pp. 183-198.Africa, LesothoDeposit - Letseng
DS201504-0187
2015
Jacob, D.E.Bussweiler, Y., Foley, S.F., Prelevic, D., Jacob, D.E.The olivine macrocryst problem: new insights from minor and trace element compositions of olivine from Lac de Gras kimberlites, Canada.Lithos, Vol. 220-223, pp. 238-252.Canada, Northwest TerritoriesDeposit - Ekati field

Abstract: This study presents detailed petrographical and geochemical investigations on remarkably fresh olivines in kimberlites from the EKATI Diamond Mine- located in the Tertiary/Cretaceous Lac de Gras kimberlite field within the Slave craton of Canada. Olivine, constituting about 42 vol.% of the analyzed samples, can be divided into two textural groups: (i) macrocrystic olivines, > 100 µm sub-rounded crystals and (ii) groundmass olivines, < 100 µm subhedral crystals. Olivines from both populations define two distinct chemical trends; a “ "mantle trend" with angular cores, showing low Ca (< 0.1 wt.% CaO) and high Ni (0.3-0.4 wt.% NiO) at varying Mg# (0.86-0.93), contrasts with a "melt trend" typified by thin (< 100 µm) rims with increasing Ca (up to 1.0 wt.% CaO) and decreasing Ni (down to 0.1 wt.% NiO) contents at constant Mg# (~ 0.915). These findings are in agreement with recent studies suggesting that virtually all olivine is composed of xenocrystic (i.e. mantle-related) cores with phenocrystic (i.e. melt-related) overgrowths, thereby challenging the traditional view that the origin of kimberlitic olivine can be distinguished based on size and morphology. The two main trends can be further resolved into sub-groups refining the crystallization history of olivine; the mantle trend indicates a multi-source origin that samples the layered lithosphere below the Slave craton, whereas the melt trend represents multi-stage crystallization comprising a differentiation trend starting at mantle conditions and a second trend controlled by the crystallization of additional phases (e.g. chromite) and changing magma conditions (e.g. oxidation). These trends are also seen in the concentrations of trace elements not routinely measured in olivine (e.g. Na, P, Ti, Co, Sc, Zr). Trace element mapping with LA-ICP-MS reveals the distribution of these elements within olivine grains. The trace element distribution between the two trends appears to be consistent with phenocrystic olivine overgrowths mainly originating from dissolved orthopyroxene, showing enrichment in Zr, Ga, Nb, Sc, V, P, Al, Ti, Cr, Ca and Mn in the melt trend. In a sample of magmatic kimberlite from the Leslie pipe, the amount of xenocrystic and phenocrystic olivine is estimated to be around 23 vol.% and 19 vol.%, respectively. Subtraction of this xenocrystic olivine from the Leslie bulk composition, aimed at estimating the parental kimberlite melt, results in a minor decrease of Mg# (by about 0.01) and SiO2 content (by about 3 wt.%), whereas CaO increases (by about 3 wt.%).
DS201508-0350
2015
Jacob, D.E.Dongre, A.N., Jacob, D.E., Stern, R.A.Subduction related origin of eclogite xenoliths from the Wajrakarur kimberlite field, Eastern Dharwar craton, southern India: constraints from petrology and geochemistry.Geochimica et Cosmochimica Acta, Vol. 166, pp. 165-188.IndiaDeposit - Wajrakarur
DS201606-1093
2015
Jacob, D.E.Howell, D., Griffin, W.L., Yang, J., Gain, S., Stern, R.A., Huang, J-X., Jacob, D.E., Xu, X., Stokes, A.J., O'Reilly, S.Y., Pearson, N.J.Diamonds in ophiolites: contamination or a new diamond growth environment?Earth and Planetary Science Letters, Vol. 430, pp. 284-295.Asia, TibetLuobusa Massif Type Iib

Abstract: For more than 20 years, the reported occurrence of diamonds in the chromites and peridotites of the Luobusa massif in Tibet (a complex described as an ophiolite) has been widely ignored by the diamond research community. This skepticism has persisted because the diamonds are similar in many respects to high-pressure high-temperature (HPHT) synthetic/industrial diamonds (grown from metal solvents), and the finding previously has not been independently replicated. We present a detailed examination of the Luobusa diamonds (recovered from both peridotites and chromitites), including morphology, size, color, impurity characteristics (by infrared spectroscopy), internal growth structures, trace-element patterns, and C and N isotopes. A detailed comparison with synthetic industrial diamonds shows many similarities. Cubo-octahedral morphology, yellow color due to unaggregated nitrogen (C centres only, Type Ib), metal-alloy inclusions and highly negative View the MathML sourcedC13 values are present in both sets of diamonds. The Tibetan diamonds (n=3n=3) show an exceptionally large range in View the MathML sourcedN15 (-5.6 to +28.7‰+28.7‰) within individual crystals, and inconsistent fractionation between {111} and {100} growth sectors. This in contrast to large synthetic HPHT diamonds grown by the temperature gradient method, which have with View the MathML sourcedN15=0‰ in {111} sectors and +30‰+30‰ in {100} sectors, as reported in the literature. This comparison is limited by the small sample set combined with the fact the diamonds probably grew by different processes. However, the Tibetan diamonds do have generally higher concentrations and different ratios of trace elements; most inclusions are a NiMnCo alloy, but there are also some small REE-rich phases never seen in HPHT synthetics. These characteristics indicate that the Tibetan diamonds grew in contact with a C-saturated Ni-Mn-Co-rich melt in a highly reduced environment. The stable isotopes indicate a major subduction-related contribution to the chemical environment. The unaggregated nitrogen, combined with the lack of evidence for resorption or plastic deformation, suggests a short (geologically speaking) residence in the mantle. Previously published models to explain the occurrence of the diamonds, and other phases indicative of highly reduced conditions and very high pressures, have failed to take into account the characteristics of the diamonds and the implications for their formation. For these diamonds to be seriously considered as the result of a natural growth environment requires a new understanding of mantle conditions that could produce them.
DS201606-1102
2016
Jacob, D.E.Kvassnytsya, V., Wirth, R., Piazolo, S., Jacob, D.E., Trimby, P.Surface morphology and structural types of natural impact apographitic diamonds. IN RUSSIANSverkhtverdie Materiali ( Ukraine) in RUSSIAN, No. 2, pp. 3-17.TechnologyMorphology of lonsdaleite, diamond

Abstract: External and internal morphologies of natural impact apographitic diamonds (paramorphoses) have been studied. The (0001) surface morphology of the paramorphoses reflects their phase composition and the structural relationship of its constituting phases. Growth and etch figures together with the elements of crystal symmetry of lonsdaleite and diamond are developed on these surfaces. The crystal size of lonsdaleite is up to 100 nm, and that of diamond is up to 300 nm. Two types of structural relations between graphite, lonsdaleite, and diamond in the paramorphoses are observed: the first type (black, black-gray, colorless and yellowish paramorphoses): the (0001) graphite face is parallel to the (100) lonsdaleite face and parallel to (111) diamond; the second type (milky-white paramorphoses): the (0001) graphite is parallel to the (100) lonsdaleite and parallel to the (112) diamond. The first type of the paramorphoses contains lonsdaleite, diamond, graphite or diamond, lonsdaleite, the second type of the paramorphoses contains predominantly diamond. The direct phase transition of graphite ? lonsdaleite and/or graphite ?diamond occurred in the paramorphoses of the first type. A successive phase transition graphite ? lonsdaleite ? diamond was observed in the paramorphoses of the second type. The structure of the paramorphoses of this type shows characteristic features of recrystallization.
DS201607-1303
2016
Jacob, D.E.Jacob, D.E., Piazolo, S., Screiber, A., Trimby, P.Redox-freezing and nucleation of diamond via magnetite formation in the Earth's mantle.Nature Communications, Vol. 7, June 21, 7p.Africa, BotswanaDeposit - Orapa

Abstract: Diamonds and their inclusions are unique probes into the deep Earth, tracking the deep carbon cycle to >800?km. Understanding the mechanisms of carbon mobilization and freezing is a prerequisite for quantifying the fluxes of carbon in the deep Earth. Here we show direct evidence for the formation of diamond by redox reactions involving FeNi sulfides. Transmission Kikuchi Diffraction identifies an arrested redox reaction from pyrrhotite to magnetite included in diamond. The magnetite corona shows coherent epitaxy with relict pyrrhotite and diamond, indicating that diamond nucleated on magnetite. Furthermore, structures inherited from h-Fe3O4 define a phase transformation at depths of 320 -330?km, the base of the Kaapvaal lithosphere. The oxidation of pyrrhotite to magnetite is an important trigger of diamond precipitation in the upper mantle, explaining the presence of these phases in diamonds.
DS201609-1701
2016
Jacob, D.E.Aulbach, S., Jacob, D.E.Major and trace elements in cratonic mantle eclogites and pyroxenites reveal heterogeneous sources and metamorphic processing of low pressure protoliths.Lithos, Vol. 262, pp. 586-605.MantleEclogite

Abstract: There is a growing body of evidence for the origin of cratonic mantle eclogite xenoliths by low-pressure formation in now-recycled ocean floors. Because they have protoliths ultimately derived from the convecting mantle, their study can potentially yield unprecedented insights into as yet little-understood palaeo-geodynamic regimes, once primary (fractional crystallisation, accumulation, mixing) and secondary processes (kimberlite infiltration, metasomatism) affecting their compositions are understood. This is achieved using diagnostic concentrations or ratios of the analytically and geologically most robust elements (major and minor elements, transition metals, REE), and aided by comparison to natural and modelled analogues. Here, mineral compositions taken from the literature were used to reconstruct bulk rocks and assign the samples to eclogites (further divided into high-Mg, low-Mg and high-Ca types), pyroxenites and their gabbroic (Eu* > 1.05) counterparts. Various protolith types - formed predominantly by < 1 GPa crystallisation from broadly picritic magmas leaving garnet-poor mantle sources - are identified: (1) Many high-Mg eclogites lie on modelled crystallisation trends between 0.5 and < 1 GPa. Some have elevated FeO contents with lower SiO2 and CaO possibly requiring Fe-rich pyroxenite heterogeneities in their mantle source. (2) Many high-Ca eclogites may be the differentiated (higher Na2O, TiO2 and FeO at lower MgO) equivalents of high-Mg eclogites, following modelled crystallisation trends at somewhat lower pressure (0.05 to 0.5 GPa). Other high-Ca eclogites with low FeO were produced during interaction with fluids and melts in mélange-type settings. (3) Low-Mg eclogites, with intermediate MgO content, are too FeO-rich to be intermediary crystallisation products of the same parental melt and are ascribed to melting out of Fe-rich lithologies possibly related to recycling of eclogite and/or contamination with ferromanganese sediments. (4) The positive Eu anomalies in gabbroic eclogites require accumulation of substantial amounts of plagioclase, consistent with their low FeO and TiO2 contents, but their simultaneously low MgO contents suggest that they interacted with residual melts. (5) The elevated CaO and low Al2O3 in pyroxenite may indicate clinopyroxene-rich high- or low-pressure cumulate protoliths, but high Cr2O3 and MgO, combined with low HREE and high LREE in many of these samples, suggests formation by hybridisation of eclogite-derived melt with peridotite.
DS201610-1860
2016
Jacob, D.E.Forster, M.W., Prelevic, D., Schmuck, H.R., Jacob, D.E.Melting and dynamic metasomatism of mixed harzburgite + glimmerite mantle source: implications for the genesis of orogenic potassic magmas.Chemical Geology, in press available 10p.MantleUltrapotassic magmas

Abstract: Tectonically young, orogenic settings are commonly the sites of post-collisional silica-rich ultrapotassic magmas with extreme K2O-contents of up to 9 wt% and K2O/Na2O > 2. Many experimental studies investigating the generation of these melts have concentrated on melting of homogenous phlogopite bearing peridotites, whereas geochemical signatures indicate the involvement of at least two types of source rocks: ultra-depleted and K and trace elements-enriched ones. We report the results of melting experiments at 1-2 GPa of mixed glimmerite and harzburgite, in which these rock types make up two halves each capsule. Melting begins in the glimmerite, and its metasomatic effects on the harzburgite are apparent at 1100 °C even before melt pools are visible. The first melts are Na-rich, seen in zoning of olivines and as growth of clinopyroxene in the harzburgite, but change at higher degrees of melting to produce a typical lamproite-like melt with K2O > 10 wt%. A major advantage of this study is the preservation of distinct melts in different parts of the capsule, which reflect a process of dynamic metasomatism: within the harzburgite matrix, the infiltrating melt derived from melting of the glimmerite changes consistently with the distance of travel through the harzburgite, enabling quantification of the metasomatic effects as an increase in SiO2 and K2O. This results principally from assimilation of orthopyroxene, which increases the Ol/Opx ratio of the residual harzburgite. The effects of quench olivine growth are recognizable and can be quantified due to a step-change in composition at the glimmerite/harzburgite border: the large total surface area of olivine and small melt fraction mean that the amount of quench olivine is high within the harzburgite, but negligible in the almost completely molten glimmerite. Melts of the glimmerite contain up to 8-10 wt% K2O and 53 wt% SiO2, which increase to 55-56 wt% after interaction with the harzburgite. Mediterranean lamproites resemble melts of glimmerite, whereas melts that have interacted with harzburgite are more similar to less potassic, but more SiO2-rich shoshonites of the Mediterranean region.
DS201705-0877
2017
Jacob, D.E.Sommer, H., Jacob, D.E., Stern, R.A., Petts, D., Mattey, D.P., Pearson, D.G.Fluid induced transition from banded kyanite to bimineralic eclogite and implications for the evolution of cratons.Geochimica et Cosmochimica Acta, in press available 55p.Africa, South AfricaDeposit - Roberts Victor

Abstract: Heterogeneous, modally banded kyanite-bearing and bimineralic eclogites from the lithospheric mantle, collected at the Roberts Victor Diamond mine (South Africa), show a reaction texture in which kyanite is consumed. Geothermobarometric calculations using measured mineral compositions in Perple_X allowed the construction of a P-T path showing a steep, cool prograde metamorphic gradient of 2 °C/km to reach peak conditions of 5.8 GPa and 890 °C for the kyanite eclogite. The kyanite-out reaction formed bimineralic eclogite and is probably an integral part of the mineralogical evolution of most archetypal bimineralic eclogites at Roberts Victor and potentially elsewhere. The kyanite-out reaction occured at close to peak pressure (5.3 GPa) and was associated with a rise in temperature to 1380 °C. Mass balance calculations show that upon breakdown, the kyanite component is fully accommodated in garnet and omphacite via a reaction system with low water fugacity that required restricted fluid influx from metasomatic sources. The d18O values of garnets are consistently higher than normal mantle values. Each sample has its characteristic trend of d18O variance between garnets in the kyanite-bearing sections and those in the bimineralic parts covering a range between 5.1‰ and 6.8‰. No systematic change in O-isotope signature exists across the sample population. Differences in garnet trace element signatures between differing lithologies in the eclogites are significant. Grossular-rich garnets coexisting with kyanite have strong positive Eu-anomalies and low Gd/Yb ratios, while more pyrope-rich garnets in the bimineralic sections have lost their positive Eu-anomaly, have higher Gd/Yb ratios and generally higher heavy rare earth element contents. Garnets in the original kyanite-bearing portions thus reflect the provenance of the rocks as metamorphosed gabbros/troctolites. The kyanite-out reaction was most likely triggered by a heating event in the subcratonic lithosphere. As kyanite contains around 100 ppm of H2O it is suggested that the kyanite-out reaction, once initiated by heating and restricted metasomatic influx, was promoted by the release of water contained in the kyanite. The steep (high-P low-T) prograde P-T path defining rapid compression at low heating rates is atypical for subduction transport of eclogites into the lithospheric mantle. Such a trajectory is best explained in a model where strong lateral compression forces eclogites downward to higher pressures, supporting models of cratonic lithosphere formation by lateral collision and compression.
DS201707-1323
2017
Jacob, D.E.Forster, M.W., Orelevic, D., Schmuck, H.R., Buhre, S., Veter, M., Mertz-Kraus, R., Foley, S.F., Jacob, D.E.Melting and dynamic metasomatism of mixed harzburgite + glimmerite mantle source: implications for the genesis of orogenic potassic magmas.Chemical Geology, Vol. 455, pp. 182-191.Mantlemetasomatism

Abstract: Tectonically young, orogenic settings are commonly the sites of post-collisional silica-rich ultrapotassic magmas with extreme K2O-contents of up to 9 wt% and K2O/Na2O > 2. Many experimental studies investigating the generation of these melts have concentrated on melting of homogenous phlogopite bearing peridotites, whereas geochemical signatures indicate the involvement of at least two types of source rocks: ultra-depleted and K and trace elements-enriched ones. We report the results of melting experiments at 1–2 GPa of mixed glimmerite and harzburgite, in which these rock types make up two halves each capsule. Melting begins in the glimmerite, and its metasomatic effects on the harzburgite are apparent at 1100 °C even before melt pools are visible. The first melts are Na-rich, seen in zoning of olivines and as growth of clinopyroxene in the harzburgite, but change at higher degrees of melting to produce a typical lamproite-like melt with K2O > 10 wt%. A major advantage of this study is the preservation of distinct melts in different parts of the capsule, which reflect a process of dynamic metasomatism: within the harzburgite matrix, the infiltrating melt derived from melting of the glimmerite changes consistently with the distance of travel through the harzburgite, enabling quantification of the metasomatic effects as an increase in SiO2 and K2O. This results principally from assimilation of orthopyroxene, which increases the Ol/Opx ratio of the residual harzburgite. The effects of quench olivine growth are recognizable and can be quantified due to a step-change in composition at the glimmerite/harzburgite border: the large total surface area of olivine and small melt fraction mean that the amount of quench olivine is high within the harzburgite, but negligible in the almost completely molten glimmerite. Melts of the glimmerite contain up to 8–10 wt% K2O and 53 wt% SiO2, which increase to 55–56 wt% after interaction with the harzburgite. Mediterranean lamproites resemble melts of glimmerite, whereas melts that have interacted with harzburgite are more similar to less potassic, but more SiO2-rich shoshonites of the Mediterranean region.
DS201709-1956
2017
Jacob, D.E.Aulbach, S., Jacob, D.E., Cartigny, P., Stern, R.A., Simonetti, S.S., Worner, G., Viljoen, K.S.Eclogite xenoliths from Orapa: ocean crust recycling, mantle metasomatism and carbon cycling at the western Zimbabwe craton margin.Geochimica et Cosmochimica Acta, Vol. 213, pp. 574-592.Africa, Botswanadeposit - Orapa

Abstract: Major- and trace-element compositions of garnet and clinopyroxene, as well as 87Sr/86Sr in clinopyroxene and d18O in garnet in eclogite and pyroxenite xenoliths from Orapa, at the western margin of the Zimbabwe craton (central Botswana), were investigated in order to trace their origin and evolution in the mantle lithosphere. Two groups of eclogites are distinguished with respect to 87Sr/86Sr: One with moderate ratios (0.7026-0.7046) and another with 87Sr/86Sr >0.7048 to 0.7091. In the former group, heavy d18O attests to low-temperature alteration on the ocean floor, while 87Sr/86Sr correlates with indices of low-pressure igneous processes (Eu/Eu*, Mg#, Sr/Y). This suggests relatively undisturbed long-term ingrowth of 87Sr at near-igneous Rb/Sr after metamorphism, despite the exposed craton margin setting. The high-87Sr/86Sr group has mainly mantle-like d18O and is suggested to have interacted with a small-volume melt derived from an aged phlogopite-rich metasome. The overlap of diamondiferous and graphite-bearing eclogites and pyroxenites over a pressure interval of ~3.2 to 4.9 GPa is interpreted as reflecting a mantle parcel beneath Orapa that has moved out of the diamond stability field, due to a change in geotherm and/or decompression. Diamondiferous eclogites record lower median 87Sr/86Sr (0.7039) than graphite-bearing samples (0.7064) and carbon-free samples (0.7051), suggesting that interaction with the - possibly oxidising - metasome-derived melt caused carbon removal in some eclogites, while catalysing the conversion of diamond to graphite in others. This highlights the role of small-volume melts in modulating the lithospheric carbon cycle. Compared to diamondiferous eclogites, eclogitic inclusions in diamonds are restricted to high FeO and low SiO2, CaO and Na2O contents, they record higher equilibrium temperatures and garnets have mostly mantle-like O isotopic composition. We suggest that this signature was imparted by a sublithospheric melt with contributions from a clinopyroxene-rich source, possibly related to the ca. 2.0 Ga Bushveld event.
DS201709-2003
2017
Jacob, D.E.Jacob, D.E., Stern, R.A., Chapman, J., Piazoli, S.Insights into diamond formation from polycrystalline diamond aggregates. DiamonditesGoldschmidt Conference, abstract 1p.Africa, South Africadeposit - Venetia

Abstract: Polycrystalline diamond aggregates (diamondites) are produced by rapid crystal nucleation caused by extreme carbon supersaturation in mantle fluids. They may form episodically and under variable chemical conditions, providing snapshots of diamond formation in the Earth’s mantle. Diamondites, thus, represent an extreme end member of diamond formation mechanisms, while forming via the same processes and ingredients as the gem-sized diamonds. We present results on a large suite of diamondites from the Venetia mine (South Africa), comprising a complete characterisation of the diamonds and their silicate inclusions and intergrowths. The highlighted characteristic of this sample suite is its heterogeneity in all aspects, from affiliated silicate to diamond composition and texture of the diamond aggregates. The diamond grains in the samples are intergrown with silicates (garnets, clinopyroxenes, phlogopites) comprising a websteritic-eclogitic and a peridotiticpyroxenitic suite of minerals. Diamonds, regardless of their affiliation based on their silicate phases, overlap in carbon and nitrogen composition and have d13C values between -28 and -8 ‰, d15N values of 0.8 to 16.3 ‰ and nitrogen contents of 4 to 2329 ppm. The entire range of carbon and nitrogen variability of the suite is also reflected in some individual samples. Cathodoluminescence imaging visualizes different zones in the samples that can be interpreted as different growth events with differing nitrogen contents and d15N decoupled from d13C values, in line with the variability off nitrogen aggregation states. Electron backscatter diffraction analyses identify an original texture of randomly intergrown diamond grains that is partly changed by deformation and newly grown smaller diamond grains. The large overall variability suggesting episodic formation of diamondite with nitrogen from crustal sources.
DS201709-2056
2017
Jacob, D.E.Sommer, H., Jacob, D.E., Stern, R.A., Petts, D., Mattey, D.P., Pearson, D.G.Fluid induced transition from banded kyanite to bimineralic eclogite and implications for the evolution of cratons.Goldschmidt Conference, abstract 1p.Africa, South Africadeposit - Roberts Victor

Abstract: Heterogeneous, modally banded kyanite-bearing and bimineralic eclogites from the lithospheric mantle, collected at the Roberts Victor Diamond mine (South Africa), show a reaction texture in which kyanite is consumed. Geothermobarometric calculations using measured mineral compositions in Perple_X allowed the construction of a P-T path showing a steep, cool prograde metamorphic gradient of 2 °C/km to reach peak conditions of 5.8 GPa and 890 °C for the kyanite eclogite. The kyanite-out reaction formed bimineralic eclogite and is probably an integral part of the mineralogical evolution of most archetypal bimineralic eclogites at Roberts Victor and potentially elsewhere. The kyanite-out reaction occured at close to peak pressure (5.3 GPa) and was associated with a rise in temperature to 1380 °C. Mass balance calculations show that upon breakdown, the kyanite component is fully accommodated in garnet and omphacite via a reaction system with low water fugacity that required restricted fluid influx from metasomatic sources. The d18O values of garnets are consistently higher than normal mantle values. Each sample has its characteristic trend of d18O variance between garnets in the kyanite-bearing sections and those in the bimineralic parts covering a range between 5.1‰ and 6.8‰. No systematic change in O-isotope signature exists across the sample population. Differences in garnet trace element signatures between differing lithologies in the eclogites are significant. Grossular-rich garnets coexisting with kyanite have strong positive Eu-anomalies and low Gd/Yb ratios, while more pyrope-rich garnets in the bimineralic sections have lost their positive Eu-anomaly, have higher Gd/Yb ratios and generally higher heavy rare earth element contents. Garnets in the original kyanite-bearing portions thus reflect the provenance of the rocks as metamorphosed gabbros/troctolites. The kyanite-out reaction was most likely triggered by a heating event in the subcratonic lithosphere. As kyanite contains around 100 ppm of H2O it is suggested that the kyanite-out reaction, once initiated by heating and restricted metasomatic influx, was promoted by the release of water contained in the kyanite. The steep (high-P low-T) prograde P-T path defining rapid compression at low heating rates is atypical for subduction transport of eclogites into the lithospheric mantle. Such a trajectory is best explained in a model where strong lateral compression forces eclogites downward to higher pressures, supporting models of cratonic lithosphere formation by lateral collision and compression.
DS201710-2212
2017
Jacob, D.E.Aulbach, S., Jacob, D.E., Cartigny, P., Stern, R.A., Simonetti, S.S., Womer, G., Viljoen, K.S.Eclogite xenoliths from Orapa: Ocean crust recycling, mantle metasomatism and carbon cycling at the western Zimbabwe craton margin.Geochimica et Cosmochinica Acta, Vol. 213, pp. 574-592.Africa, Botswanadeposit - Orapa

Abstract: Major- and trace-element compositions of garnet and clinopyroxene, as well as 87Sr/86Sr in clinopyroxene and d18O in garnet in eclogite and pyroxenite xenoliths from Orapa, at the western margin of the Zimbabwe craton (central Botswana), were investigated in order to trace their origin and evolution in the mantle lithosphere. Two groups of eclogites are distinguished with respect to 87Sr/86Sr: One with moderate ratios (0.7026-0.7046) and another with 87Sr/86Sr >0.7048 to 0.7091. In the former group, heavy d18O attests to low-temperature alteration on the ocean floor, while 87Sr/86Sr correlates with indices of low-pressure igneous processes (Eu/Eu*, Mg#, Sr/Y). This suggests relatively undisturbed long-term ingrowth of 87Sr at near-igneous Rb/Sr after metamorphism, despite the exposed craton margin setting. The high-87Sr/86Sr group has mainly mantle-like d18O and is suggested to have interacted with a small-volume melt derived from an aged phlogopite-rich metasome. The overlap of diamondiferous and graphite-bearing eclogites and pyroxenites over a pressure interval of ~3.2 to 4.9 GPa is interpreted as reflecting a mantle parcel beneath Orapa that has moved out of the diamond stability field, due to a change in geotherm and/or decompression. Diamondiferous eclogites record lower median 87Sr/86Sr (0.7039) than graphite-bearing samples (0.7064) and carbon-free samples (0.7051), suggesting that interaction with the - possibly oxidising - metasome-derived melt caused carbon removal in some eclogites, while catalysing the conversion of diamond to graphite in others. This highlights the role of small-volume melts in modulating the lithospheric carbon cycle. Compared to diamondiferous eclogites, eclogitic inclusions in diamonds are restricted to high FeO and low SiO2, CaO and Na2O contents, they record higher equilibrium temperatures and garnets have mostly mantle-like O isotopic composition. We suggest that this signature was imparted by a sublithospheric melt with contributions from a clinopyroxene-rich source, possibly related to the ca. 2.0 Ga Bushveld event.
DS201804-0689
2018
Jacob, D.E.Forster, M.W., Prelevic, D., Schmuck, H.R., Buhre, S., Marschall, H.R., Mertz-Kraus, R., Jacob, D.E.Melting phologopite rich MARID: lamproites and the role of alkalis in olivine liquid Ni partioning.Chemical Geology, Vol. 476, 1, pp. 429-440.Technologylamproites

Abstract: In this study, we show how veined lithospheric mantle is involved in the genesis of ultrapotassic magmatism in cratonic settings. We conducted high pressure experiments to simulate vein + wall rock melting within the Earth's lithospheric mantle by reacting assemblages of harzburgite and phlogopite-rich hydrous mantle xenoliths. These comprised a mica-, amphibole-, rutile-, ilmenite-, diopside (MARID) assemblage at 3-5 GPa and 1325-1450 °C. Melting of the MARID assemblages results in infiltration of melt through the harzburgite, leading to its chemical alteration. At 3 and 4 GPa, melts are high in K2O (> 9 wt%) with K2O/Na2O > > 2 comparable to anorogenic lamproites. Higher pressures and temperatures (5 GPa/1450 °C) lead to increasing MgO contents of the melt and to some extent lower K2O contents (5-7 wt%) at equally high K2O/Na2O ratios. Our experiments provide insights into the role of alkalis in nickel-partitioning (DNi) between olivine and ultrapotassic melt. We observe that the high contents of Na, K, and Al are indicative of high DNi values, implying that the melt polymerization is the dominant factor influencing the olivine/melt nickel partitioning. The change of DNi as a function of melt composition results in a pressure independent, empirical geothermometer: Element oxides represent the composition of the glass (in wt%), and DNi is the liquid/olivine Ni-partitioning coefficient. We propose that this geothermometer is applicable to all natural silicate melts that crystallized olivine in a temperature interval between 1000 and 1600 °C. Application to glass-olivine pairs from calc-alkaline settings (Mexico), MORB (East Pacific Rise), and OIB (Hawaii) yielded reasonable values of 996-1199 °C, 1265 °C, and 1330 °C, respectively.
DS201809-1991
2017
Jacob, D.E.Aulbach, S., Jacob, D.E., Cartigny, P., Stern, R.A., Simonetti, S.S., Worner, G., Viljoen, K.S.Eclogite xenoliths from Orapa: Ocean crust recycling, mantle metasomatism and carbon cycling at the western Zimbabwe craton margin.Geochimica et Cosmochimica Acta, Vol. 213, 1, pp. 574-592.Africa, Botswanadeposit - Orapa

Abstract: Major- and trace-element compositions of garnet and clinopyroxene, as well as 87Sr/86Sr in clinopyroxene and d18O in garnet in eclogite and pyroxenite xenoliths from Orapa, at the western margin of the Zimbabwe craton (central Botswana), were investigated in order to trace their origin and evolution in the mantle lithosphere. Two groups of eclogites are distinguished with respect to 87Sr/86Sr: One with moderate ratios (0.7026-0.7046) and another with 87Sr/86Sr >0.7048 to 0.7091. In the former group, heavy d18O attests to low-temperature alteration on the ocean floor, while 87Sr/86Sr correlates with indices of low-pressure igneous processes (Eu/Eu*, Mg#, Sr/Y). This suggests relatively undisturbed long-term ingrowth of 87Sr at near-igneous Rb/Sr after metamorphism, despite the exposed craton margin setting. The high-87Sr/86Sr group has mainly mantle-like d18O and is suggested to have interacted with a small-volume melt derived from an aged phlogopite-rich metasome. The overlap of diamondiferous and graphite-bearing eclogites and pyroxenites over a pressure interval of ~3.2 to 4.9 GPa is interpreted as reflecting a mantle parcel beneath Orapa that has moved out of the diamond stability field, due to a change in geotherm and/or decompression. Diamondiferous eclogites record lower median 87Sr/86Sr (0.7039) than graphite-bearing samples (0.7064) and carbon-free samples (0.7051), suggesting that interaction with the - possibly oxidising - metasome-derived melt caused carbon removal in some eclogites, while catalysing the conversion of diamond to graphite in others. This highlights the role of small-volume melts in modulating the lithospheric carbon cycle. Compared to diamondiferous eclogites, eclogitic inclusions in diamonds are restricted to high FeO and low SiO2, CaO and Na2O contents, they record higher equilibrium temperatures and garnets have mostly mantle-like O isotopic composition. We suggest that this signature was imparted by a sublithospheric melt with contributions from a clinopyroxene-rich source, possibly related to the ca. 2.0 Ga Bushveld event.
DS201809-2044
2018
Jacob, D.E.Jacob, D.E., Stern, R.A., Stachel, T., Piazolo, S.Polycrystalline diamonds and their mantle derived mineral and fluid intergrowths. (Aggregates, framesites, boart, diamondite)Goldschmidt Conference, 1p. AbstractAfrica, South Africadeposit - Venetia

Abstract: Polycrystalline diamond aggregates (framesites, boart, diamondite) are an understudied variety of mantle diamond, but can make up 20% of the production in some Group I kimberlites. Their polycrystalline nature indicates rapid precipitation from carbon-oversaturated fluids and individual PDAs often contain a chemically heterogeneous suite of websteritic and pyroxenitic inclusions and minerals intimately intergrown with the diamond crystals. Geochemical and microstructural evidence suggests that fluid-driven redox reactions with lithospheric material occurring episodically over millions of years play a major role in freezing carbon in the subcratonic lithosphere (Jacob et al., 2000; 2016; Mikhail et al., 2014). A suite of 39 samples from the Venetia kimberlite pipe in South Africa allows a more detailed look at the diamondforming fluids. 13C values in the diamonds measured by secondary ion mass spectrometry range from +2 to -28 and cover the entire range for PDA from the literature. Nitrogen concentrations are mostly very low (less than 100 at ppm), but reach up to 2660 at ppm in individual samples. These high nitrogen concentrations in concert with mostly positive 15N values of up to +17 and some very negative 3C values suggest crustal material as the source of the nitrogen and the carbon. However, detailed analysis of the sample provides evidence for a more complex growth history followed by alteration. Individual diamond crystals show complex growth zonations by cathodoluminescence imaging that can be related with the carbon and nitrogen isotopic compositions and points to growth incorporating several pulses of carbon-nitrogen fluid with distinct isotopic compositions. Most of these growth events show decoupled carbon and nitrogen systematics. In addition, EBSD identifies deformation and recrystallization and nitrogen aggregation states range from pure IaA to pure IaB, supporting a heterogeneous and episodic growth history.
DS201810-2307
2018
Jacob, D.E.Cruz-Uribe, A.M., Feineman, M.D., Zack, T., Jacob, D.E.Asssessing trace element (dis) equilibrium and the application of single element thermometers in metamorphic rocks.Lithos, Vol. 314-315, pp. 1-15.Globalthermobarometry

Abstract: Empirical and experimental calibration of single element solubility thermometers, such as Zr-in-rutile, Zr-in-titanite, Ti-in-zircon, and Ti-in-quartz, within the past 13 years has greatly expanded our ability to assess the pressure and temperature conditions of individual minerals associated with specific textures in metamorphic rocks. Combined with advances in in situ techniques for analyzing trace concentrations, this has led to an increase in the combined use of single element thermometers, geochronometers, and isotope ratios, often simultaneously, in metamorphic minerals. Here we review the calibration and application of single element thermometers at the pressure and temperature conditions of interest in metamorphic rocks. We discuss to what extent accessory phase equilibrium and trace element equilibrium are attained in metamorphic systems, and the thermodynamic and kinetic framework within which trace element equilibrium is assessed. As an example, we present a comprehensive study of trace element distribution during rutile replacement by titanite in rocks that experienced high-temperature amphibolite-facies overprinting and those that underwent low-temperature blueschist-facies overprinting from a variety of subduction-related terranes worldwide. We find that trace element distributions approach equilibrium partition coefficients in rocks from amphibolite-facies overprinted terranes, whereas trace element distributions do not approach equilibrium in rocks that experienced blueschist-facies overprinting. We caution that single element thermometers that rely upon slow-diffusing high field strength elements should not be applied to rocks equilibrated at <600 °C unless attainment of trace element equilibrium can be demonstrated.
DS201812-2776
2019
Jacob, D.E.Aulbach, S., Heaman, L.M., Jacob, D.E., Viljoen, K.S.Ages and sources of mantle eclogites: ID-TIMS and in situ MC-ICPMS Pb-Sr isotope sytematics of clinopyroxene.Chemical Geology, Vol. 503, pp. 15-28.Mantleeclogite

Abstract: Strontium and Pb isotopic compositions of clinopyroxene (cpx) in selected samples from three well-characterised eclogite suites with oceanic crustal protoliths (Lace/Kaapvaal craton, Orapa/Zimbabwe craton and Koidu/West African craton) were acquired by high-precision isotope dilution thermal ionisation mass spectrometry (ID-TIMS) and in situ multicollector-laser ablation-inductively-coupled plasma mass spectrometry (MC-LA-ICPMS). The aims of this study are twofold: (1) assess their utility to obtain formation or resetting age constraints and identify elemental signatures that enhance the chances of successful age dating, and (2) to confirm the veracity and utility of results obtained by novel MC-LA-ICPMS techniques. Strontium-Pb isotope systematics of eclogitic cpx measured in this study are decoupled and may reflect addition of unsupported radiogenic Sr during seawater alteration or interaction with oceanic sediments in subduction mélanges, and/or disturbance due to mantle metasomatism, to which the more incompatible Pb is more susceptible. Despite a complex history, subsets of samples yield meaningful model dates. Clinopyroxene fractions from Lace with high Pb contents (36?ppm), unradiogenic Pb isotopic compositions (206Pb/204Pb?=?13.5713.52) and low 238U/204Pb (1.01.5) give single-stage model Pb dates of 2.902.84?Ga. In contrast, samples from Orapa plot to the right of the Geochron and do not yield meaningful Pb model ages. However, these data do define secondary isochrons that can be modelled to yield minimum age constraints on major events affecting the cratonic lithosphere. Within the uncertainties, the resultant 2.18?±?0.45?Ga age obtained for Koidu eclogites reflect disturbance of the Pb isotope system due to subduction beneath the craton linked to the Eburnean orogeny, while they retained their unradiogenic 87Sr/86Sr (0.7016). Similarly, the age for samples from Orapa (2.20?±?0.54?Ga) is interpreted as an overprint age related to Palaeoproterozoic accretion at the western craton margin. Gabbroic eclogites (Eu/Eu*?>?1) with plagioclase-rich protoliths having low time-integrated Rb/Sr and U/Pb retain the least radiogenic Sr and, in part, Pb. High model µ (9.0 to 9.1) for several eclogites from Lace with elevated LREE, Th and Pb abundances reflects ca. 3.0?Ga addition of a sedimentary component, possibly derived from reworking of a high-µ basaltic protocrust, as observed on other cratons. We suggest that sample targeting can be usefully guided by fast-throughput in situ LA-ICPMS techniques, which largely yield results identical to ID-TIMS, albeit at lower precision, and which can further help identify kimberlite contamination in the mineral separates used for solution work.
DS201905-1062
2019
Jacob, D.E.Nestola, F., Jacob, D.E., Pamato, M.G., Pasqualatto, L., Oliveira, B., Greene, S., Perritt, S., Chinn, I., Milani, S., Kueter, N., Sgreva, N., Nimis, P., Secco, L., Harris, J.W.Protogenetic garnet inclusions and the age of diamonds.Geology, doi.10.1130/G45781.1Mantlediamond inclusions

Abstract: Diamonds are the deepest accessible “fragments” of Earth, providing records of deep geological processes. Absolute ages for diamond formation are crucial to place these records in the correct time context. Diamond ages are typically determined by dating inclusions, assuming that they were formed simultaneously with their hosts. One of the most widely used mineral inclusions for dating diamond is garnet, which is amenable to Sm-Nd geochronology and is common in lithospheric diamonds. By investigating worldwide garnet-bearing diamonds, we provide crystallographic evidence that garnet inclusions that were previously considered to be syngenetic may instead be protogenetic, i.e., they were formed before the host diamond, raising doubts about the real significance of many reported diamond “ages.” Diffusion modeling at relevant pressures and temperatures, however, demonstrates that isotopic resetting would generally occur over geologically short time scales. Therefore, despite protogenicity, the majority of garnet-based ages should effectively correspond to the time of diamond formation. On the other hand, our results indicate that use of large garnet inclusions (e.g., >100 µm) and diamond hosts formed at temperatures lower than ~1000 °C is not recommended for diamond age determinations.
DS201912-2825
2020
Jacob, D.E.Shirey, S.B., Smit, K.V., Pearson, D.G., Walter, M.J., Aulbach, S., Brenker, F.E., Bureau, H., Burnham, A.D., Cartigny, P., Chacko, T., Frost, D.J., Hauri, E.H., Jacob, D.E., Jacobsen, S.D., Kohn, S.C., Luth, R.W., Mikhail, S., Navon, O., Nestola, F., NimDiamonds and the mantle geodynamics of carbon: deep mantle carbon and evolution from the diamond record.IN: Deep carbon: past to present, Orcutt, Daniel, Dasgupta eds., pp. 89-128.Mantlegeodynamics

Abstract: The science of studying diamond inclusions for understanding Earth history has developed significantly over the past decades, with new instrumentation and techniques applied to diamond sample archives revealing the stories contained within diamond inclusions. This chapter reviews what diamonds can tell us about the deep carbon cycle over the course of Earth’s history. It reviews how the geochemistry of diamonds and their inclusions inform us about the deep carbon cycle, the origin of the diamonds in Earth’s mantle, and the evolution of diamonds through time.
DS202001-0039
2020
Jacob, D.E.Shirey, S.B., Smit, K.V., Pearson, D.G., Walter, M.J., Aulbach, S., Brenker, F.E., Bureau, H., Burnham, A.D., Cartigny, P., Chacko, T., Frost, D.J., Hauri, E.H., Jacob, D.E., Jacobsen, S.D., Kohn, S.C., Luth, R.W., Mikhail, S., Navon, O., Nestola, F., NimDiamonds and mantle geodynamics of carbon: IN: Deep Carbon: past to present. Editors Orcutt, Danielle, Dasgupta, pp. 89-128.Mantlegeodynamics

Abstract: The science of studying diamond inclusions for understanding Earth history has developed significantly over the past decades, with new instrumentation and techniques applied to diamond sample archives revealing the stories contained within diamond inclusions. This chapter reviews what diamonds can tell us about the deep carbon cycle over the course of Earth’s history. It reviews how the geochemistry of diamonds and their inclusions inform us about the deep carbon cycle, the origin of the diamonds in Earth’s mantle, and the evolution of diamonds through time.
DS202004-0519
2020
Jacob, D.E.Howell, D., Stachel, T., Stern, R.A., Pearson, D.G., Nestola, F., Hardman, M.F., Harris, J.W., Jaques, A.L., Shirery, S.B., Cartigny, P., Smit, K.V., Aulbach, S., Brenker, F.E., Jacob, D.E., Thomassot, E., Walter, M.J., Navon, O.Deep carbon through time: Earth's diamond record and its implications for carbon cycling and fluid speciation in the mantle.(peridotite and eclogite used)Geochimica et Cosmochimica Acta, Vol. 275, pp. 99-122.Mantlecarbon

Abstract: Diamonds are unrivalled in their ability to record the mantle carbon cycle and mantle fO2 over a vast portion of Earth’s history. Diamonds’ inertness and antiquity means their carbon isotopic characteristics directly reflect their growth environment within the mantle as far back as ~3.5 Ga. This paper reports the results of a thorough secondary ion mass spectrometry (SIMS) carbon isotope and nitrogen concentration study, carried out on fragments of 144 diamond samples from various locations, from ~3.5 to 1.4 Ga for P [peridotitic]-type diamonds and 3.0 to 1.0 Ga for E [eclogitic]-type diamonds. The majority of the studied samples were from diamonds used to establish formation ages and thus provide a direct connection between the carbon isotope values, nitrogen contents and the formation ages. In total, 908 carbon isotope and nitrogen concentration measurements were obtained. The total d¹³C data range from -17.1 to -1.9 ‰ (P = -8.4 to -1.9 ‰; E = -17.1 to -2.1‰) and N contents range from 0 to 3073 at. ppm (P = 0 to 3073 at. ppm; E = 1 to 2661 at. ppm). In general, there is no systematic variation with time in the mantle carbon isotope record since > 3 Ga. The mode in d¹³C of peridotitic diamonds has been at -5 (±2) ‰ since the earliest diamond growth ~3.5 Ga, and this mode is also observed in the eclogitic diamond record since ~3 Ga. The skewness of eclogitic diamonds’ d¹³C distributions to more negative values, which the data establishes began around 3 Ga, is also consistent through time, with no global trends apparent. No isotopic and concentration trends were recorded within individual samples, indicating that, firstly, closed system fractionation trends are rare. This implies that diamonds typically grow in systems with high excess of carbon in the fluid (i.e. relative to the mass of the growing diamond). Any minerals included into diamond during the growth process are more likely to be isotopically reset at the time of diamond formation, meaning inclusion ages would be representative of the diamond growth event irrespective of whether they are syngenetic or protogenetic. Secondly, the lack of significant variation seen in the peridotitic diamonds studied is in keeping with modeling of Rayleigh isotopic fractionation in multicomponent systems (RIFMS) during isochemical diamond precipitation in harzburgitic mantle. The RIFMS model not only showed that in water-maximum fluids at constant depths along a geotherm, fractionation can only account for variations of <1‰, but also that the principal d¹³C mode of -5 ± 1‰ in the global harzburgitic diamond record occurs if the variation in fO2 is only 0.4 log units. Due to the wide age distribution of P-type diamonds, this leads to the conclusion that the speciation and oxygen fugacity of diamond forming fluids has been relatively consistent. The deep mantle has therefore generated fluids with near constant carbon speciation for 3.5 Ga.
DS202008-1398
2020
Jacob, D.E.Greene, S., Jacob, D.E., O'Reilly, S.Y., Henry, H., Pinter, Z., Heaman, L.Extensive prekimberlitic lithosphere modification recorded in Jericho mantle xenoliths in kimberlites, Slave Craton.Goldschmidt 2020, 1p. AbstractCanada, Northwest Territoriesdeposit - Jericho

Abstract: Wehrlite and pyroxenite xenoliths and megacrysts from the Jericho kimberlite were analyzed by µXRF and EBSD, and for major elements, trace elements, and isotopes (Pb-Sr- O) in major phases. Thermobarometry places these samples at 60 - 180 km and 600 - 1200 ??C. While modes and textures vary, many samples have olivine-olivine grain boundaries with straight edges and 120° angle junctions, indicating granoblastic recrystallisation, while clinopyroxene and orthopyroxene are complexly intergrown. Clinopyroxene twins and subgrains recording orientations distinct from the encapsulating grain were detected using EBSD and are inferred to represent recent modification processes. Several distinct garnet compositions were measured, with multiple thin garnet rims in some samples suggesting possible successive stages of garnet crystallisation. Complex chromium zoning in garnet is detected by µXRF in several samples (fig.1). Pb-Pb ages for most samples are similar to the age of kimberlite entrainment (173 Ma), but the shallowest pyroxenite sample preserves the most radiogenic Pb composition, intercecting concordia at 0.7 - 1.1 Ga, and is the only sample with d18O above the mantle range (6.2±0.1 ‰). The deepest sample has the lowest d18O (5.5±0.1 ‰) and radiogenic 87Sr/86Sr similar to MARID rocks (0.709±1 ‰). These results suggest the Jericho lithosphere experienced several melt/fluid injection events that modified substantial portions of the sampled section soon before kimberlite entrainment.
DS202102-0212
2021
Jacob, D.E.Otter, L.M., Forster, M.W., Belousova, E., O'Reilly, P., Nowak, D., Parlk, S., Clar, S., Foley, S.F., Jacob, D.E.GGR cutting-edge review nanoscale chemical imaging by photo-induced force microscopy: technical aspects and application to the geosciences. ( not specific to diamonds)Geostandards and Geoanalytical Research, doi:10.111/ GGR.12373. 51p. PdfGlobalspectroscopy, mineralogy

Abstract: Photo-induced force microscopy (PiFM) is a new-frontier technique that combines the advantages of atomic force microscopy with infrared spectroscopy and allows for the simultaneous acquisition of 3D topographic data with molecular chemical information at high spatial (~ 5 nm) and spectral (~ 1 cm-1) resolution at the nanoscale. This non-destructive technique is time efficient as it requires only conventional mirror-polishing and has fast mapping rates on the order of a few minutes that allow the study of dynamic processes via time series. Here, we review the method’s historical development, working principle, data acquisition, evaluation, and provide a comparison with traditional geochemical methods. We review PiFM studies in the areas of materials science, chemistry, and biology. In addition, we provide the first applications for geochemical samples including the visualisation of faint growth zonation in zircons, the identification of fluid speciation in high-pressure experimental samples, and of nanoscale organic phases in biominerals. We demonstrate that PiFM analysis is a time- and cost-efficient technique combining high-resolution surface imaging with molecular chemical information at the nanoscale and, thus, complements and expands traditional geochemical methods.
DS202107-1128
2019
Jacob, D.E.Shirey, S.B., Smit, K.V., Pearson, D.G., Walter, M.J., Aulbach, S., Brenker, F.E., Bureau, H., Burnham, A.D., Cartigny, P., Chacko, T., Frost, D.J., Hauri, E.H., Jacob, D.E., Jacobsen, S.D., Kohn, S.C., Luth, R.W., Mikhail, S., Navon, O.. Nestola, F., NimDiamonds and mantle geodynamics of carbon.Deep Carbon - Cambridge University Press , Cambridge.org 40p. PdfMantlecarbon
DS1987-0314
1987
Jacob, H.L.Jacob, H.L.Inventaire des gisements de mineraux industriels off rant un potentiel pourla production de minerales.Quebec Department of Mines, MB 87-43, 68p.QuebecIndustrial minerals
DS1998-0677
1998
Jacob, H.L.Jacob, H.L.Caracterisation de gites de syenite a nepheline comme source de materiaux feldspathiques.Quebec Department of Mines, DP 98-05, p. 52.QuebecGeology, nepheline syenite
DS200612-0632
2006
Jacob, J.Jacob, J., Ward, J.D., Bluck, B.J., Scholz, R.A., Frimmel, H.E.Some observations on Diamondiferous bedrock gully trapsites on Late Cainozoic, marine cut platforms of the Sperrgebiet, Namibia.Ore Geology Reviews, Vol. 28, 4, pp. 493-506.Africa, NamibiaGeomorphology, alluvials, placers
DS201412-0417
2014
Jacob, J.Jacob, J.The Namibian megaplacer: 106 years on and still going strong.GSSA Kimberley Diamond Symposium and Trade Show provisional programme, Sept. 11, title onlyAfrica, NamibiaAlluvials
DS201412-0418
2014
Jacob, J.Jacob, J., Prins, C., Oelofsen, A.Determination of sampling configuration for near shore Diamondiferous gravel occurrence using geostatistical methods. Mining area no. 1 - linear beach NamdebJournal of South African Institute of Mining and Metallurgy, Vol. 114, Jan. pp. 31-38.Africa, NamibiaSampling - geostatistics
DS201605-0849
2016
Jacob, J.Jacob, J.Using the proportion of barren samples as a proxy for minimum grade in a Diamondiferous linear beach deposit - an application of the Nachman model.Diamonds Still Sparkling SAIMM 2016 Conference, Mar. 14-17, pp. 47-56.Africa, NamibiaGeostatistics
DS201609-1716
2016
Jacob, J.De Wit, M., Bhebhe, Z., Davidson, J., Haggerty, S.E., Hundt, P., Jacob, J., Lynn, M., Marshall, T.R., Skinner, C., Smithson, K., Stiefenhofer, J., Robert, M., Revitt, A., Spaggiari, R., Ward, J.Overview of diamonds resources in Africa.Episodes, Vol. 9, 2, pp. 198-238.AfricaDiamond resources - overview

Abstract: From the discovery of diamonds in South Africa in 1866 until the end of 2013, Africa is estimated to have produced almost 3.2 Bct out of a total global production of 5.03 Bct, or 63.6% of all diamonds that have ever been mined. In 2013 African countries ranked 2nd (Botswana), 3rd (DRC), 6th (Zimbabwe), 7th (Angola), 8th (South Africa), and 9th (Namibia), in terms of carat production and 1st (Botswana), 4th (Namibia), 5th (Angola), 6th (South Africa), 7th (Zimbabwe), and 9th (DRC), in terms of value of the diamonds produced. In 2013 Africa produced 70.6 Mct out of a global total of 130.5 Mct or 54.1%, which was valued at US$ 8.7 billion representing 61.5% of the global value of US$ 14.1 billion.
DS201612-2306
2016
Jacob, J.Jacob, J.Using the proportion of barren samples as a proxy for minimum grade in a Diamondiferous linear beach deposit - an application of the Nachman model.Journal of South African Institute of Mining and Metallurgy, Vol. 116, Aug. pp. 731-737.Africa, NamibiaDeposit - marine placers

Abstract: Over the past 80 years, the Namibian diamondiferous marine placer has been studied extensively to develop solutions for mining and sampling challenges. The types of studies include the statistical modelling of the distributions of the stone counts per sample; investigating the relationship between geology and the grade distribution; assessing the quality potential of the entrapment of the available diamond pulse; using predetermined acceptability of barren samples (zero proportion (Zp) samples) to model distributions; optimal sample sizes; and more. During early-stage project evaluation it is more important to find out if a particular area is likely to be above a specific cut-off grade than to focus on sampling for the purpose of accurate resource estimation. Previous work using mixed Poisson and Sichel distributions to model the abundant onshore diamond data has been very successful in modelling the long-tailed nature of these linear beach deposits. The means of these distributions are, however, sensitive to extreme values. Technical and cost constraints prevent a similar scale of sample collection in an adjacent, geologically equivalent, submerged beach environment. A method not sensitive to extreme values is thus required to make early-stage assessments of the likelihood that the grade of a particular target is above a minimum cut-off grade. The Nachman model describes the functional relationship between the mean population density and proportion of barren patches ( Zp) in a patchy environment. A prerequisite for using the Nachman model is that the underlying data must be modelled using a negative binomial distribution (NBD). The case study data is from an analogous area adjacent to the exploration target and meets the NBD requirement. It is thus appropriate to apply the Nachman model. The Nachman model provides an opportunity to use the observed Zpto predict the mean grade for an area at the very early stage of an exploration project. In future, early-stage exploration data from a homogenous geological zone exhibiting characteristics of the Nachman model assumptions can thus be used to rank and target those areas that show potential to be above the minimum required grade cut-off for follow-up sampling and inclusion in the mine planning cycle.
DS201612-2307
2016
Jacob, J.Jacob, J., Prins, C.Construction of an expert opinion based virtual orebody for a Diamondiferous linear beach deposit.Journal of South African Institute of Mining and Metallurgy, Vol. 116, July pp. 629-635.Africa, NamibiaDeposit - marine placers

Abstract: During early-stage diamond exploration projects, hard data underpinning spatial continuity is often very limited. An extreme example of this is a submerged diamondiferous marine placer target area alongside a current onshore mining area in southwestern Namibia. Although an abundance of geological and grade data exists for the adjacent onshore mining area, the target area itself contains no such information. Despite this apparent abundance of data, it is extremely difficult to obtain a variogram (Prins and Jacob, 2014) for use in this study area. The use of traditional simulation techniques is further hindered by the fact that diamond entrapment within the highly gullied footwall is non-stationary. An alternative approach for creating a simulated virtual orebody (VOB) is thus required in order to enable the assessment of sampling strategies. This paper demonstrates how expert opinion is used to generate a composite probability map for diamond concentration using a greyscale hand-sketching technique. The probability map is subsequently calibrated and populated using the diamond distribution for different raised beaches obtained from analog data based on sample results adjacent to the target area. The resultant grade simulation is used to test different sample scenarios and is a first step towards determining an appropriate sampling strategy for the target area. The VOB is used to analyse and rank the efficiency of different sampling strategies for grade determination of submerged diamondiferous linear beach exploration targets.
DS201702-0217
2017
Jacob, J.Jacob, J.Overview of the Namibian diamond megaplacer: past, present and future potential.PDAC 2017, March 6, 1p. AbstractAfrica, NamibiaAlluvials
DS201709-2004
2016
Jacob, J.Jacob, J., Prins, C.Construction of an expert opinion based virtual orebody for a Diamondiferous linear beach deposit. South African Institute of Mining and Metallurgy, Vol. 116, 7, pp. 629-336.Africa, Namibiatechnology, alluvials
DS201709-2005
2016
Jacob, J.Jacob, J., Prins, C.Using the proportion of barren samples as a proxy for minimum grade in a Diamondiferous linear beach deposit - an application of the Nachman model.South African Institute of Mining and Metallurgy, Vol. 116, 8, pp. 731-737.Africa, Namibiadeposit - Orange River

Abstract: Over the past 80 years, the Namibian diamondiferous marine placer has been studied extensively to develop solutions for mining and sampling challenges. The types of studies include the statistical modelling of the distributions of the stone counts per sample; investigating the relationship between geology and the grade distribution; assessing the quality potential of the entrapment of the available diamond pulse; using predetermined acceptability of barren samples (zero proportion (Zp) samples) to model distributions; optimal sample sizes; and more. During early-stage project evaluation it is more important to find out if a particular area is likely to be above a specific cut-off grade than to focus on sampling for the purpose of accurate resource estimation. Previous work using mixed Poisson and Sichel distributions to model the abundant onshore diamond data has been very successful in modelling the long-tailed nature of these linear beach deposits. The means of these distributions are, however, sensitive to extreme values. Technical and cost constraints prevent a similar scale of sample collection in an adjacent, geologically equivalent, submerged beach environment. A method not sensitive to extreme values is thus required to make early-stage assessments of the likelihood that the grade of a particular target is above a minimum cut-off grade. The Nachman model describes the functional relationship between the mean population density and proportion of barren patches ( Zp) in a patchy environment. A prerequisite for using the Nachman model is that the underlying data must be modelled using a negative binomial distribution (NBD). The case study data is from an analogous area adjacent to the exploration target and meets the NBD requirement. It is thus appropriate to apply the Nachman model. The Nachman model provides an opportunity to use the observed Zpto predict the mean grade for an area at the very early stage of an exploration project. In future, early-stage exploration data from a homogenous geological zone exhibiting characteristics of the Nachman model assumptions can thus be used to rank and target those areas that show potential to be above the minimum required grade cut-off for follow-up sampling and inclusion in the mine planning cycle.
DS201907-1552
2019
Jacob, J.Jacob, J., Grobbelaar, G.Onshore and nearshore diamond mining on the south-western coast of Namibia: recent activities and future exploration techniques.Journal of Gemmology, Vol. 36, 6, pp. 524-533.Africa, Namibiamining
DS1994-1565
1994
Jacob, J.P.Sears, J.W., Jacob, J.P., Poage, M.A., Sims, J.L., Skinner, L.L.Mid-continent rift analog for middle Proterozoic belt basinGeological Society of America Abstracts, Vol. 26, No. 6, April p. 62. Abstract.GlobalTectonics, Midcontinent
DS1995-0863
1995
Jacob, K.H.Jacob, K.H., et al.Self organization of mineral fabricsFractal Distribution, pp. 259-268GlobalFractals, Patterned mineral fabrics
DS2003-0633
2003
Jacob, K.H.Jacob, K.H.New concepts in global tectonicsErzmetall, Vol. 56, 1, pp. 35-8.GlobalTectonics
DS1999-0329
1999
Jacob, R.J.Jacob, R.J., Bluck, B.J., Ward, J.D.Tertiary age Diamondiferous fluvial deposits of the Lower Orange RiverValley, southwestern Africa.Economic Geology, Vol. 94, No. 5, Aug. pp. 749-58.South AfricaDiamond alluvials, Orange River area
DS201712-2695
2005
Jacob, R.J.Jacob, R.J.The erosional and Cainozoic deposition history of the Lower Orange River southwestern Africa.Thesis, Phd. University of Glasgow, 178p. PdfAfrica, South Africadeposit - Lower Orange River

Abstract: A series of terraces flanking the Lower Orange River in the study area were deposited after ca. 90% of the incision had occurred, thus only the late stage incision/depositional history of this margin is able to be addressed here. Two principal suites of river terraces are distinguished by their palaeo-courses, bedrock strath levels, overall geometry and clast assemblages: an older, higher lying Proto suite and a younger Meso suite. The Proto suite represents a long, post-Eocene, through the Oligocene into the Early Miocene, phase of incision, followed by a prolonged period of aggradation where up to 90 m of fluvial, diamondiferous deposits accumulated during the Early-Middle Miocene. The Meso suite of deposits represents shorter phrases of incision and aggradation in the Pilo-Pleistocene. The Proto and Meso deposits were built in response to both base level rise and increased supply of material from tributaries draining the Great Escarpment locally, with clast assemblage and downstream fining data indicating the latter to be the more important variable. River incision into bedrock is a topic of great interest to fluvial geomorphologists, although most data are derived from active tectonic settings. The incision of a large river into a plateau surface is relatively rare, the best known example being the Colorado River in the young (6 Ma) Grand Canyon. The Orange River in the study area represents a long-lived example of this setting, with the present day dissected topography having evolved from more confined canyon-like walls following the early incision of the Orange River in the Early Tertiary. Although a long-lived incision, the modern channel is not graded in the study area, and is actively incising. The world-wide dataset of incision rates in modern rivers indicates that the Orange River could have completed its entire incision within less than a million years. The continued downcutting of this river so long after the initial incision event is indicative of the roles of intermittent, ongoing epeirogenesis and/or eustatic influences (both of which cannot be proven at this stage), tributary input from the plateau rim (Great Escarpment) or merely the long tag time involved in landscape adjustment following incision into a plateau surface.
DS201803-0466
2018
Jacob, R.J.Nakashole, A.N., Hodgson, D.M., Chapman, R.J., Morgan, D.J., Jacob, R.J.Long term controls on continental scale bedrock river terrace deposition from integrated clast and heavy mineral assemblage analysis: an example from the Lower Orange River, Namibia. ( Diamondiferous gravel terraces)Sedimentary Geology, Vol. 364, pp. 103-120.Africa, Namibiadeposit - Orange River

Abstract: Establishing relationships between the long-term landscape evolution of drainage basins and the fill of sedimentary basins benefits from analysis of bedrock river terrace deposits. These fragmented detrital archives help to constrain changes in river system character and provenance during sediment transfer from continents (source) to oceans (sink). Thick diamondiferous gravel terrace deposits along the lower Orange River, southern Namibia, provide a rare opportunity to investigate controls on the incision history of a continental-scale bedrock river. Clast assemblage and heavy mineral data from seven localities permit detailed characterisation of the lower Orange River gravel terrace deposits. Two distinct fining-upward gravel terrace deposits are recognised, primarily based on mapped stratigraphic relationships (cross-cutting relationships) and strath and terrace top elevations, and secondarily on the proportion of exotic clasts, referred to as Proto Orange River deposits and Meso Orange River deposits. The older early to middle Miocene Proto Orange River gravels are thick (up to 50 m) and characterised by a dominance of Karoo Supergroup shale and sandstone clasts, whereas the younger Plio-Pleistocene Meso Orange River gravels (6-23 m thick) are characterised by more banded iron formation clasts. Mapping of the downstepping terraces indicates that the Proto gravels were deposited by a higher sinuosity river, and are strongly discordant to the modern Orange River course, whereas the Meso deposits were deposited by a lower sinuosity river. The heavy minerals present in both units comprise magnetite, garnet, amphibole, epidote and ilmenite, with rare titanite and zircon grains. The concentration of amphibole-epidote in the heavy minerals fraction increases from the Proto to the Meso deposits. The decrease in incision depths, recorded by deposit thicknesses above strath terraces, and the differences in clast character (size and roundness) and type between the two units, are ascribed to a more powerful river system during Proto-Orange River time, rather than reworking of older deposits, changes in provenance or climatic variations. In addition, from Proto- to Meso-Orange River times there was an increase in the proportion of sediments supplied from local bedrock sources, including amphibole-epidote in the heavy mineral assemblages derived from the Namaqua Metamorphic Complex. This integrated study demonstrates that clast assemblages are not a proxy for the character of the matrix, and vice versa, because they are influenced by the interplay of different controls. Therefore, an integrated approach is needed to improve prediction of placer mineral deposits in river gravels, and their distribution in coeval deposits downstream.
DS1988-0322
1988
Jacobberger, P.A.Jacobberger, P.A.Mapping abandoned river channels in Mali through directional filtering of thematic mapper dataRemote Sensing of Environment, Vol. 26, pp. 161-170GlobalRemote Sensing, TEM.
DS2002-0848
2002
Jacobi, R.D.Kim, J., Jacobi, R.D.Boninites: characteristics and tectonic constraints, northeastern AppalachiansPhysics and Chemistry of Earth, Vol.27,pt.A,B,C,1-3,pp.109-47.AppalachiaTectonics, Boninites
DS2002-0849
2002
Jacobi, R.D.Kim, J., Jacobi, R.D.Boninites: characteristics and tectonic constraints, northeastern AppalachiansPhysics and Chemistry of the Earth, Vol. 27, pp.109-147.Quebec, Labrador, NewfoundlandTectonics, Boninites
DS202105-0781
2021
Jacobs, D.E.Pamato, M.G., Novella, D., Jacobs, D.E., Oliveira, B., Pearson, D.G., Greene, S., Alfonso, J.C., Favero, M., Stachel, T., Alvaro, M., Nestola, F.Protogenetic sulfide inclusions in diamonds date the diamond formation event using Re-Os isotopes. Victor, JerichoGeology , Vol. 49, 4, 5p. Canada, Ontario, Nunavutdiamond inclusions

Abstract: Sulfides are the most abundant inclusions in diamonds and a key tool for dating diamond formation via Re-Os isotopic analyses. The manner in which fluids invade the continental lithospheric mantle and the time scale at which they equilibrate with preexisting (protogenetic) sulfides are poorly understood yet essential factors to understanding diamond formation and the validity of isotopic ages. We investigated a suite of sulfide-bearing diamonds from two Canadian cratons to test the robustness of Re-Os in sulfide for dating diamond formation. Single-crystal X-ray diffraction (XRD) allowed determination of the original monosulfide solid-solution (Mss) composition stable in the mantle, indicating subsolidus conditions of encapsulation, and providing crystallographic evidence supporting a protogenetic origin of the inclusions. The results, coupled with a diffusion model, indicate Re-Os isotope equilibration is sufficiently fast in sulfide inclusions with typical grain size, at mantle temperatures, for the system to be reset by the diamond-forming event. This confirms that even if protogenetic, the Re-Os isochrons defined by these minerals likely reflect the ages of diamond formation, and this result highlights the power of this system to date the timing of fluid migration in mantle lithosphere.
DS1950-0180
1954
Jacobs, D.S.Jacobs, D.S.Die Geskiedenis Van die Mynwese in die O.v.s. Tussen die Jare 1854 En 1899 ,met Spesiale Verwysing Na die Diamantbedryf.M.a. Thesis, Unisa, Bloemfontein., 136P.South AfricaMining History
DS1910-0193
1911
Jacobs, E.Jacobs, E.Diamonds in British Columbia; April, 1911Engineering and Mining Journal, Vol. 91, APRIL 22ND. PP. 797-798. ALSO Canadian MiningCanada, British ColumbiaHistory
DS1860-0340
1880
Jacobs, H.Jacobs, H., Chatrian, N.Monographie du DiamantAnvers: Legros, Also: Paris: Seppelt., 211P. PP. 69-74.GlobalGemology
DS1860-0440
1884
Jacobs, H.Jacobs, H., Chatrian, N.Le Diamant (1884)Paris: Masson, G. Editeur, Libraire De L'academie De Medicin, 358P. PP. 353-374.Africa, South Africa, Global, Borneo, Brazil, India, United StatesGemology
DS1993-0730
1993
Jacobs, J.Jacobs, J., Thomas, R.J., Weber, K.Accretion and indentation tectonics at the southern edge of the Kaapvaal craton during the Kilbaran (Grenville) orogenyGeology, Vol. 21, No. 3, March pp. 203-206Zimbabwe, southern AfricaTectonics, Orogeny, Kaapval Craton
DS1994-0822
1994
Jacobs, J.Jacobs, J., Thomas, R.J.Oblique collision at about 1.1 Ga along the southern margin of the Kaapvaalcontinent, southeast AfricaGeologische Rundschau, Vol. 83, No. 2, July pp. 322-333AfricaTectonics, Kaapval craton
DS1996-0672
1996
Jacobs, J.Jacobs, J., Thomas, R.J.Pan African rejuvenation of the C. 1.1 Ga Natal metamorphic Province (SouthAfrica): K-Ar muscovite..Journal of the Geological Society of London, Vol. 153, pt. 6, pp. 971-978South Africametamorphism, Natal Province
DS1997-0548
1997
Jacobs, J.Jacobs, J., Falter, M., Jessberger, E.K.40 Ar-39 Ar thermochronological constraints on the structural evolution of the Mesoproterozoic Natal...Precambrian Research, Vol. 86, No. 1/2, Dec. 15, pp. 71-92GlobalMetamorphic province, Argon, Tectonics, structure
DS1999-0330
1999
Jacobs, J.Jacobs, J., Thomas, R.J., Henjes-Kunst, F.Age and thermal evolution of the Mesoproterozoic Cape Meredith Complex, West Falkland.Journal of Geological Society of London, Vol. 156, No. 3, May pp. 917-28.GlobalGeochronology
DS2001-0519
2001
Jacobs, J.Jacobs, J., Thomas, R.J.A titanite fission track profile across the southeastern Archean Kaapvaal CratonJournal of African Earth Sciences, Vol.33,2,pp.323-33., Vol.33,2,pp.323-33.South AfricaGeochronology, Craton - Kaapvaal
DS2001-0520
2001
Jacobs, J.Jacobs, J., Thomas, R.J.A titanite fission track profile across the southeastern Archean Kaapvaal CratonJournal of African Earth Sciences, Vol.33,2,pp.323-33., Vol.33,2,pp.323-33.South AfricaGeochronology, Craton - Kaapvaal
DS2001-0521
2001
Jacobs, J.Jacobs, J., Thomas, R.J.A titanite fission track profile across southeastern Archean Kaapvaal Craton and the Mesoproterozoic NatalJournal of African Earth Sciences, Vol.33,2,Aug.pp.323-34.South AfricaTectonism, Metamorphism
DS2003-0634
2003
Jacobs, J.Jacobs, J., Bauer, W., Fanning, C.M.New age constraints for Grenville age metamorphism in western central Dronning MaudInternational Journal of Earth Sciences, Vol. 92, No. 3, July pp. 301-315.Antarctica, RodiniaGeochronology, Orogeny, Laurentia
DS200412-0892
2003
Jacobs, J.Jacobs, J., Bauer, W., Fanning, C.M.New age constraints for Grenville age metamorphism in western central Dronning Maud Land ( east Antarctica) and implications forInternational Journal of Earth Sciences, Vol. 92, no. 3, July pp. 301-315.Antarctica, RodiniaGeochronology Orogeny, Laurentia
DS200412-2185
2003
Jacobs, J.Yoshida, M., Jacobs, J., Santosh, M., Rajesh, H.M.Role of Pan African events in the Circum East Antarctic Orogen of East Gondwana: a critical overview.Proterozoic East Gondwana: Supercontinent assembly and Breakup. Ed. Yoshida , Geological Society of London Spe, No. 206, pp. 57-76.AntarcticaPlume, tectonics
DS200612-0375
2005
Jacobs, J.Emmel, B., Jacobs, J., Kastowski, M., Graser, G.Phanerozoic upper crustal tectonothermal development of basement rocks from central Madagascar: an integrated fission track and structural study.Tectonophysics, in pressAfrica, MadagascarGeothermometry, Gondwana
DS201604-0636
2016
Jacobs, J.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.
DS201710-2219
2017
Jacobs, J.Cerantola, V., Bykova, E., Kupenko, I., Merlini, M., Ismailova, L., McCammon, C., Bykov, M., Chumakov, A.I., Petitgirard, S., Kantor, I., Svityk, V., Jacobs, J., Hanfland, M., Mezouar, M., Prescher, C., Ruffer, R., Prakapenka, V.B., Duvbovinsky, L.How iron carbonates help form diamonds.Nature Communications, July 18 #15960Mantlecarbonate inclusions
DS1991-0778
1991
Jacobs, J.A.Jacobs, J.A.The deep interior of the earthChapman and Hall, 160p. approx. $ 30.00 United StatesGlobalBook -ad, Deep interior of the earth
DS1992-0765
1992
Jacobs, J.A.Jacobs, J.A.The earth's core in a nutshellNature, Vol. 356, No. 6367, March 26, p. 286-287MantleCore, Geophysics, seismics
DS1995-0864
1995
Jacobs, J.A.Jacobs, J.A.The earth's inner core and the geodynamo: determining their roles in theearth's history.Eos, Vol. 76, No. 25, June 20, p. 249, 253.MantleGeomagnetisM., Boundary conditions
DS1997-0549
1997
Jacobs, J.A.Jacobs, J.A.The earth's inner coreTerra Nova, Vol. 9, pp. 140-143.MantleGeodynamics, anisotropy, Inner core
DS1940-0116
1946
Jacobs, J.F.Jacobs, J.F.Diamante. #1Bloemfontein: Nas. Pers. Kennis Vir Almal, SER. No. 39. PP. 9-87.South AfricaHistory, Diamond
DS2003-0929
2003
Jacobs, P.Mees, F., Swennen, R., Van Geet, M., Jacobs, P.Applications of X ray computed tomography in the GeosciencesGeological Society of London Publ., http://bookshop.geolsoc.org.uk, SP 215, 256p. approx. $110.USGlobalBook - tomography - general interest
DS200412-1288
2003
Jacobs, P.Mees, F., Swennen, R., Van Geet, M., Jacobs, P.Applications of X ray computed tomography in the Geosciences.Geological Society of London , SP 215, 256p. approx. $110.USTechnologyBook - tomography
DS200812-0560
2008
Jacobs, P.Kervyn, M., Ernst, G.G., Harris, A.J.L., Belton, F., Mbede, E., Jacobs, P.Thermal remote sensing of the low intensity carbonatite volcanism of Oldoinyo Lengai, Tanzania,International Journal of Remote Sensing, Vol. 29, 22, pp. 6467-6499.Africa, TanzaniaCarbonatite
DS1992-0766
1992
Jacobs, S.S.Jacobs, S.S.Is the Antarctic ice sheet growing?Nature, Vol. 360, November 5, pp. 29-33AntarcticaGeomorphology, Review article on glacial activity
DS200612-0633
2006
Jacobs, T.Jacobs, T.Any diamonds in the diagnostic coal?Nature Biotechnology, Vol. 24, 8, p. 930. (1p).TechnologyCarbon - coal
DS201511-1851
2015
Jacobsen, B.Kaminsky, F., Matzel, J., Jacobsen, B., Hutcheon, I., Wirth, R.Isotopic fractionation of oxygen and carbin in decomposed lower-mantle inclusions in diamond. Rio Soriso Mineralogy and Petrology, DOI 10. 1007/s00710-015-0401-7South America, Brazil, Mato GrossoJuina area

Abstract: Two carbonatitic mineral assemblages, calcite + wollastonite and calcite + monticellite, which are encapsulated in two diamond grains from the Rio Soriso basin in the Juina area, Mato Grosso State, Brazil, were studied utilizing the NanoSIMS technique. The assemblages were formed as the result of the decomposition of the lower-mantle assemblage calcite + CaSi-perovskite + volatile during the course of the diamond ascent under pressure conditions from 15 to less than 0.8 GPa. The oxygen and carbon isotopic compositions of the studied minerals are inhomogeneous. They fractionated during the process of the decomposition of primary minerals to very varying values: d18O from -3.3 to +15.4?‰SMOW and d13C from -2.8 to +9.3?VPDB. These values significantly extend the mantle values for these elements in both isotopically-light and isotopically-heavy areas.
DS201602-0235
2015
Jacobsen, B.H.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.
DS201605-0850
2016
Jacobsen, S.Jacobsen, S.Earth's deep mantle water cycle: what diamond inclusions might be telling us.DCO Edmonton Diamond Workshop, June 8-10MantleDiamond Inclusions
DS202009-1631
2020
Jacobsen, S.Hyung, E., Jacobsen, S.The 142Nd/144 Nd variations in mantle derived rocks provide constraints on the stirring rate of the mantle from the Hadean to the present.Proceedings of the National Academy of Sciences, Voll. 176, no. 26, 14738-44. pdfMantleplate tectonics

Abstract: Early silicate differentiation events for the terrestrial planets can be traced with the short-lived 146Sm-142Nd system (~100-My half-life). Resulting early Earth-produced 142Nd/144Nd variations are an excellent tracer of the rate of mantle mixing and thus a potential tracer of plate tectonics through time. Evidence for early silicate differentiation in the Hadean (4.6 to 4.0 Ga) has been provided by 142Nd/144Nd measurements of rocks that show both higher and lower (±20 ppm) values than the present-day mantle, demonstrating major silicate Earth differentiation within the first 100 My of solar system formation. We have obtained an external 2s uncertainty at 1.7 ppm for 142Nd/144Nd measurements to constrain its homogeneity/heterogeneity in the mantle for the last 2 Ga. We report that most modern-day mid-ocean ridge basalt and ocean island basalt samples as well as continental crustal rocks going back to 2 Ga are within 1.7 ppm of the average Earth 142Nd/144Nd value. Considering mafic and ultramafic compositions, we use a mantle-mixing model to show that this trend is consistent with a mantle stirring time of about 400 My since the early Hadean. Such a fast mantle stirring rate supports the notion that Earth’s thermal and chemical evolution is likely to have been largely regulated by plate tectonics for most of its history. Some young rocks have 142Nd/144Nd signatures marginally resolved (~3 ppm), suggesting that the entire mantle is not equally well homogenized and that some silicate mantle signatures from an early differentiated mantle (>4.1 Ga ago) are preserved in the modern mantle.
DS1984-0374
1984
Jacobsen, S.B.Jacobsen, S.B., Quick, J.E., Wasserburg, G.J.A Neodymium and Strontium Isotopic Study of the Trinity Peridotite- implic Ations for Mantle Evolution.Earth and Planetary Science Letters, Vol. 68, No. 3, JUNE PP. 361-378.United States, CaliforniaGeochronology
DS1992-0670
1992
Jacobsen, S.B.Harper, C.L.Jr., Jacobsen, S.B.Evidence from coupled 147 Sm-143 neodymium and 146 Sm-142 neodymium systematics for very early (4.5-Gyr) differentiation of the earth's mantleNature, Vol. 360, No. 6406, December 24/31, pp. 728-732GlobalGeochronology, Mantle
DS1992-0767
1992
Jacobsen, S.B.Jacobsen, S.B., Harper, C.J.Isotopic modeling of crust and mantle evolutionV.m. Goldschmidt Conference Program And Abstracts, Held May 8-10th. Reston, p. A 54. abstractMantleGeochronology, Crust
DS1996-0601
1996
Jacobsen, S.B.Harper, C.L., Jacobsen, S.B.Evidence for 182 Hafnium in the Early Solar system and constraints on the time scale of terrestrial accretion and core formation.Geochimica Et Cosmochimica Acta, Vol. 60, No. 7, pp. 1131-53.MantleDensity - core
DS1998-0678
1998
Jacobsen, S.B.Jacobsen, S.B., Yin, Q.Models for the accretion and early differentiation of the EarthMineralogical Magazine, Goldschmidt abstract, Vol. 62A, p. 694-5.MantleAccretion
DS2003-0635
2003
Jacobsen, S.B.Jacobsen, S.B.How old is planet Earth?Science, No. 5625, June 6, p. 1513.EarthGeochronology
DS2003-0636
2003
Jacobsen, S.B.Jacobsen, S.B.Geochemistry - lost terrains of early EarthNature, No. 6926, Feb. 27, pp. 901-2.MantleGeochemistry
DS200412-0893
2003
Jacobsen, S.B.Jacobsen, S.B.How old is planet Earth?Science, No. 5625, June 6, p. 1513.TechnologyGeochronology
DS200412-1457
2004
Jacobsen, S.B.O'Connell, R.J., Kellogg, J.B., Jacobsen, S.B.Heterogeneity and geochemical reservoirs in the mantle.Geochimica et Cosmochimica Acta, 13th Goldschmidt Conference held Copenhagen Denmark, Vol. 68, 11 Supp. July, ABSTRACT p.A558.MantleGeochemistry
DS200512-0472
2005
Jacobsen, S.B.Jacobsen, S.B.The Hf-W isotopic system and the origin of the Earth and Moon.Annual Review of Earth and Planetary Sciences, Vol. 33, May pp. 531-570.Review - geochronology
DS200512-0927
2005
Jacobsen, S.B.Saha, A., Basu, A.R., Jacobsen, S.B., Poreda, R.J., Yin, Q.Z., Yogodzinski, G.M.Slab devolatization and Os and Pb mobility in the mantle wedge of the Kamchatka arc.Earth and Planetary Science Letters, Advanced in press,Russia, KamchatkaGeochronology, slab
DS200912-0331
2009
Jacobsen, S.B.Jacobsen, S.B.The growth of the continental crust: isotopic constraints on timing and rates.Goldschmidt Conference 2009, p. A580 Abstract.MantleGeochronology
DS2003-1300
2003
Jacobsen, S.D.Smyth, J.R., Holl, C.M., Frost, D.J., Jacobsen, S.D., Langenhorst, F.Structural systematics of hydrous ring woodite and water in Earth's interiorAmerican Mineralogist, Vol. 88, 10, Oct. pp. 1402-7.MantleMineralogy
DS200412-0219
2004
Jacobsen, S.D.Bromiley, G.D., Keppler, H., McCammon, C., Bromiley, F.A., Jacobsen, S.D.Hydrogen solubility and speciation in natural gem quality chromian diopside.American Mineralogist, Vol. 89, 6, pp. 941-949.TechnologyPetrology, experimental ( not specific to diamonds)
DS200412-1863
2003
Jacobsen, S.D.Smyth, J.R., Holl, C.M., Frost, D.J., Jacobsen, S.D., Langenhorst, F., McCammon, C.A.Structural systematics of hydrous ring woodite and water in Earth's interior.American Mineralogist, Vol. 88, 10, Oct. pp. 1402-7.MantleMineralogy
DS200512-0638
2005
Jacobsen, S.D.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
DS200612-0327
2006
Jacobsen, S.D.Demouchy, S., Jacobsen, S.D., Gaillard, F., Stern, C.R.Rapid magma ascent recorded by water diffusion profiles in mantle olivine.Geology, Vol. 34, 6, June pp. 429-432.Mantle, South America, ChileMagmatism, xenoliths - not specific to diamonds
DS200712-0476
2007
Jacobsen, S.D.Jacobsen, S.D., Van der Lee, S., Smyth, J.R., Holl, C.M.Detecting hydration in the Earth's mantle.Frontiers in Mineral Sciences 2007, Joint Meeting of Mineralogical societies Held June 26-28, Cambridge, Abstract Volume p.187-188.MantleWater
DS200712-0477
2007
Jacobsen, S.D.Jacobsen, S.D., Van der Lee, S., Smyth, J.R., Holl, C.M.Detecting hydration in the Earth's mantle.Frontiers in Mineral Sciences 2007, Joint Meeting of Mineralogical societies Held June 26-28, Cambridge, Abstract Volume p.187-188.MantleWater
DS201212-0727
2012
Jacobsen, S.D.Thomas, S-M., Bina, C.R., Jacobsen, S.D., Goncharov, A.F.Radiative heat transfer in a hydrous mantle transition zone.Earth and Planetary Science Letters, Vol. 357-358, pp. 130-138.MantleGothermometry
DS201312-0147
2013
Jacobsen, S.D.Chang, Y-Y., Jacobsen, S.D., Lin, J-F., Bina, C.R., Thomas, S-M., Wu, J., Shen, G., Xiao, Y., Chow, P., Frost, D.J., McCammon, C.A., Dera, P.Spin transition off F23+ in Al bearing phase D: an alternative explanation for small scale seismic scatterers in the mid-lower mantle.Earth and Planetary Science Letters, Vol. 382, pp. 1-9.MantleGeophysics, seismics
DS201412-0779
2014
Jacobsen, S.D.Schmandt, B., Jacobsen, S.D., Becker, T.W., Liu, Z., Dueker, K.G.Dehydration melting at the top of the lower mantle.Science, Vol. 344, 6189, June 13, pp. 1265-68.MantleWater in transition zone
DS201603-0368
2015
Jacobsen, S.D.Chang, Y-Y., Jacobsen, S.D., Bina, C.R., Thomas, S-M., Smyth, J.R., Frost, D.J., Boffa Ballaran, T., McCammon, C.A., Hauri, E.H., Inoue, T., Yurimoto, H., Meng, Y., Dera, P.Comparative compressibility of hydrous wadsleyite and ringwoodite: effect of H2O and implications for detecting water in the transition zone.Journal of Geophysical Research,, Vol. 120, 12, pp. 8259-8280.MantleRingwoodite

Abstract: Review of recent mineral physics literature shows consistent trends for the influence of Fe and H2O on the bulk modulus (K0) of wadsleyite and ringwoodite, the major phases of Earth's mantle transition zone (410-660?km). However, there is little consensus on the first pressure derivative, K0'?=?(dK/dP)P=0, which ranges from about 4 to >5 across experimental studies and compositions. Here we demonstrate the importance of K0' in evaluating the bulk sound velocity of the transition zone in terms of water content and provide new constraints on the effect of H2O on K0' for wadsleyite and ringwoodite by conducting a comparative compressibility study. In the experiment, multiple crystals of hydrous Fo90 wadsleyite containing 2.0 and 0.25?wt?% H2O were loaded into the same diamond anvil cell, along with hydrous ringwoodite containing 1.4?wt?% H2O. By measuring their pressure-volume evolution simultaneously up to 32?GPa, we constrain the difference in K0' independent of the pressure scale, finding that H2O has no effect on K0', whereas the effect of H2O on K0 is significant. The fitted K0' values of hydrous wadsleyite (0.25 and 2.0?wt?% H2O) and hydrous ringwoodite (1.4?wt?% H2O) examined in this study were found to be identical within uncertainty, with K0' ~3.7(2). New secondary-ion mass spectrometry measurements of the H2O content of these and previously investigated wadsleyite samples shows the bulk modulus of wadsleyite is reduced by 7.0(5)?GPa/wt?% H2O, independent of Fe content for upper mantle compositions. Because K0' is unaffected by H2O, the reduction of bulk sound velocity in very hydrous regions of transition zone is expected to be on the order of 1.6%, which is potentially detectible in high-resolution, regional seismology studies.
DS201608-1430
2016
Jacobsen, S.D.Palot, M., Jacobsen, S.D., Townsend, J.P., Nestols, F., Marquardt, K., Harris, J.W., Stachel, T., McCammon, C.A., Pearson, D.G.Evidence for H2O bearing fluids in the lower mantle from diamond inclusion.Lithos, in press available 27p.South America, BrazilSao Luis

Abstract: In this study, we report the first direct evidence for water-bearing fluids in the uppermost lower mantle from natural ferropericlase crystal contained within a diamond from São Luíz, Brazil. The ferropericlase exhibits exsolution of magnesioferrite, which places the origin of this assemblage in the uppermost part of the lower mantle. The presence of brucite-Mg(OH)2 precipitates in the ferropericlase crystal reflects the later-stage quenching of H2O-bearing fluid likely in the transition zone, which has been trapped during the inclusion process in the lower mantle. Dehydration melting may be one of the key processes involved in transporting water across the boundary between the upper and lower mantle.
DS201611-2149
2016
Jacobsen, S.D.Zhang, L., Smyth, J.R., Allaz, J., Kawazoe, T., Jacobsen, S.D., Jin, Z.Transition metals in the transition zone: crystal chemistry of minor element substitution in wadsleyite.American Mineralogist, Vol. 101, pp. 2322-2330.TechnologyWadsleyite

Abstract: As the most abundant solid phase at depths of 410-525 km, wadsleyite constitutes a large geochemical reservoir in the Earth. To better understand the implications of minor element substitution and cation ordering in wadsleyite, we have synthesized wadsleyites coexisting with pyroxenes with 2-3 wt% of either TiO2, Cr2O3, V2O3, CoO, NiO, or ZnO under hydrous conditions in separate experiments at 1300 °C and 15 GPa. We have refined the crystal structures of these wadsleyites by single-crystal X-ray diffraction, analyzed the compositions by electron microprobe, and estimated M3 vacancy concentration from b/a cell-parameter ratios. According to the crystal structure refinements, Cr and V show strong preferences for M3 over M1 and M2 sites and significant substitution up to 2.9 at% at the tetrahedral site (T site). Ni, Co, and Zn show site preferences similar to those of Fe with M1˜ M3 > M2 > T. The avoidance of Ni, Co, and Fe for the M2 site in both wadsleyite and olivine appears to be partially controlled by crystal field stabilization energy (CFSE). The estimated CFSE values of Ni2+, Co2+, and Zn2+ at three distinct octahedral sites show a positive correlation with octahedral occupancy ratios [M2/(M1+M3)]. Ti substitutes primarily into the M3 octahedron, rather than M1, M2, or T sites. Ti, Cr, and V each have greater solubility in wadsleyite than in olivine. Therefore these transition metal cations may be enriched in a melt or an accessory phase if hydrous melting occurs on upward convection across the wadsleyite-olivine boundary and may be useful as indicators of high-pressure origin.
DS201807-1540
2018
Jacobsen, S.D.Zhang, L., Smyth, J.R., Kawazoe, T., Jacobsen, S.D., Qin, S.Transition metals in the transition zone: partitioning of Ni, Co, and Zn between olivine, wadsleyite, ringwoodite, and clineoenstatite.Contributions to Mineralogy and Petrology, 10.1007/ s00410-018-1478-x 10p.Mantlemelting

Abstract: Ni, Co, and Zn are widely distributed in the Earth’s mantle as significant minor elements that may offer insights into the chemistry of melting in the mantle. To better understand the distribution of Ni2+, Co2+, and Zn2+ in the most abundant silicate phases in the transition zone and the upper mantle, we have analyzed the crystal chemistry of wadsleyite (Mg2SiO4), ringwoodite (Mg2SiO4), forsterite (Mg2SiO4), and clinoenstatite (Mg2Si2O6) synthesized at 12-20 GPa and 1200-1400 °C with 1.5-3 wt% of either NiO, CoO, or ZnO in starting materials. Single-crystal X-ray diffraction analyses demonstrate that significant amounts of Ni, Co, and Zn are incorporated in octahedral sites in wadsleyite (up to 7.1 at%), ringwoodite (up to 11.3 at%), olivine (up to 2.0 at%), and clinoenstatite (up to 3.2 at%). Crystal structure refinements indicate that crystal field stabilization energy (CFSE) controls both cation ordering and transition metal partitioning in coexisting minerals. According to electron microprobe analyses, Ni and Co partition preferentially into forsterite and wadsleyite relative to coexisting clinoenstatite. Ni strongly prefers ringwoodite over coexisting wadsleyite with DRw/WdNi?=?4.13. Due to decreasing metal-oxygen distances with rising pressure, crystal field effect on distribution of divalent metal ions in magnesium silicates is more critical in the transition zone relative to the upper mantle. Analyses of Ni partitioning between the major upper-mantle phases implies that Ni-rich olivine in ultramafic rocks can be indicative of near-primary magmas.
DS201907-1524
2019
Jacobsen, S.D.Anzolini, C., Wang, F., Harris, G.A., Locock, A.J., Zhang, D., Nestola, F., Peruzzo, L., Jacobsen, S.D., Pearson, D.G.Nixonite, Na2Ti6O13, a new mineral from a metasomatized mantle garnet pyroxenite from the western Rae Craton, Darby kimberlite field, Canada.American Mineralogist, in press available 26p.Canada, Nunavutdeposit - Darby

Abstract: Nixonite (IMA 2018-133), ideally Na2Ti6O13, is a new mineral found within a heavily-metasomatized pyroxenite xenolith from the Darby kimberlite field, beneath the west central Rae Craton, Canada. It occurs as microcrystalline aggregates, 15 to 40 µm in length. Nixonite is isostructural with jeppeite, K2Ti6O13, with a structure consisting of edge- and corner-shared titanium-centered octahedra that enclose alkali-metal ions. The Mohs hardness is estimated to be between 5 and 6 by comparison to jeppeite and the calculated density is 3.51(1) g/cm3. Electron microprobe wavelength-dispersive spectroscopic analysis (average of 6 points) yielded: Na2O 6.87, K2O 5.67 CaO 0.57, TiO2 84.99, V2O3 0.31, Cr2O3 0.04, MnO 0.01, Fe2O3 0.26, SrO 0.07, total 98.79 wt%. The empirical formula, based on 13 O atoms, is: (Na1.24K0.67Ca0.06)S1.97(Ti5.96V0.023Fe0.018)S6.00O13 with minor amounts of Cr and Mn. Nixonite is monoclinic, space group C2/m, with unit-cell parameters a = 15.3632(26) Å, b = 3.7782(7) Å, c = 9.1266(15) Å, ß = 99.35(15)º and V = 522.72(1) Å3, Z = 2. Based on the average of seven integrated multi-grain diffraction images, the strongest diffraction lines are [dobs in Å (I in %) (h k l)]: 3.02 (100) (3 1 0) , 3.66 (75) (1 1 0), 7.57 (73) (2 0 0), 6.31 (68) (2 0 -1), 2.96 (63) (3 1 -1), 2.96 (63) (2 0 -3) and 2.71 (62) (4 0 2). The five main Raman peaks of nixonite, in order of decreasing intensity, are at: 863, 280, 664, 135 and 113 cm-1. Nixonite is named after Peter H. Nixon, a renowned scientist in the field of kimberlites and mantle xenoliths. Nixonite occurs within a pyroxenite xenolith in a kimberlite, in association with rutile, priderite, perovskite, freudenbergite and ilmenite. This complex Na-K-Ti rich metasomatic mineral assemblage may have been produced by a fractionated Na-rich kimberlitic melt that infiltrated a mantle-derived garnet pyroxenite and reacted with rutile during kimberlite crystallization.
DS201908-1825
2019
Jacobsen, S.D.Wenz, M.D., Jacobsen, S.D., Zhang, D., Regier, M., Bausch, H.J., Dera, P.K., Rivers, M., Eng, P., Shirey, S.B., Pearson, D.G.Fast identification of mineral inclusions in diamond at GSECARS using synchrotron X-ray microtomography, radiography and diffraction.Journal of Synchrotron Radiation, Vol. 26, doi.org/10.1107 /S1600577519006854 6p. PdfMantlediamond inclusions

Abstract: Mineral inclusions in natural diamond are widely studied for the insight that they provide into the geochemistry and dynamics of the Earth's interior. A major challenge in achieving thorough yet high rates of analysis of mineral inclusions in diamond derives from the micrometre-scale of most inclusions, often requiring synchrotron radiation sources for diffraction. Centering microinclusions for diffraction with a highly focused synchrotron beam cannot be achieved optically because of the very high index of refraction of diamond. A fast, high-throughput method for identification of micromineral inclusions in diamond has been developed at the GeoSoilEnviro Center for Advanced Radiation Sources (GSECARS), Advanced Photon Source, Argonne National Laboratory, USA. Diamonds and their inclusions are imaged using synchrotron 3D computed X-ray microtomography on beamline 13-BM-D of GSECARS. The location of every inclusion is then pinpointed onto the coordinate system of the six-circle goniometer of the single-crystal diffractometer on beamline 13-BM-C. Because the bending magnet branch 13-BM is divided and delivered into 13-BM-C and 13-BM-D stations simultaneously, numerous diamonds can be examined during coordinated runs. The fast, high-throughput capability of the methodology is demonstrated by collecting 3D diffraction data on 53 diamond inclusions from Juína, Brazil, within a total of about 72 h of beam time.
DS201910-2285
2019
Jacobsen, S.D.Meyer, N.A., Wenz, M.D., Walsh, J.P.S., Jacobsen, S.D., Locock, A.J., Harris, J.W.Goldschmidtite, ( K,REE,Sr) (Nb,Cr)03: a new perovskite supergroup mineral found in diamond from Koffiefontein, South Africa.American Mineralogist, Vol. 104, pp. 1345-1350.Africa, South Africadeposit - Koffiefontein

Abstract: Goldschmidtite is a new perovskite-group mineral (IMA No. 2018-034) with the ideal formula (K,REE,Sr)(Nb,Cr)O3. A single grain of goldschmidtite with a maximum dimension of ~100 µm was found as an inclusion in a diamond from the Koffiefontein pipe in South Africa. In addition to the dark green and opaque goldschmidtite, the diamond contained a Cr-rich augite (websteritic paragenesis) and an intergrowth of chromite, Mg-silicate, and unidentified K-Sr-REE-Nb-oxide. Geothermobarometry of the augite indicates that the depth of formation was ~170 km. The chemical composition of gold-schmidtite determined by electron microprobe analysis (n = 11, WDS, wt%) is: Nb2O5 44.82, TiO2 0.44, ThO2 0.10, Al2O3 0.35, Cr2O3 7.07, La2O3 11.85, Ce2O3 6.18, Fe2O3 1.96, MgO 0.70, CaO 0.04, SrO 6.67, BaO 6.82, K2O 11.53, total 98.53. The empirical formula (expressed to two decimal places) is (K0.50La0.15Sr0.13Ba0.09Ce0.08)S0.95(Nb0.70Cr0.19Fe0.05Al0.01Mg0.04Ti0.01)S1.00O3. Goldschmidtite is cubic, space group Pm3m, with unit-cell parameters: a = 3.9876(1) Å, V = 63.404(6) Å3, Z = 1, resulting in a calculated density of 5.32(3) g/cm3. Goldschmidtite is the K-analog of isolueshite, (Na,La)NbO3. Raman spectra of goldschmidtite exhibit many second-order broad bands at 100 to 700 cm-1 as well as a pronounced peak at 815 cm-1, which is possibly a result of local ordering of Nb and Cr at the B site. The name goldschmidtite is in honor of the eminent geochemist Victor Moritz Goldschmidt (1888-1947), who formalized perovskite crystal chemistry and identified KNbO3 as a perovskite-structured compound.
DS201912-2825
2020
Jacobsen, S.D.Shirey, S.B., Smit, K.V., Pearson, D.G., Walter, M.J., Aulbach, S., Brenker, F.E., Bureau, H., Burnham, A.D., Cartigny, P., Chacko, T., Frost, D.J., Hauri, E.H., Jacob, D.E., Jacobsen, S.D., Kohn, S.C., Luth, R.W., Mikhail, S., Navon, O., Nestola, F., NimDiamonds and the mantle geodynamics of carbon: deep mantle carbon and evolution from the diamond record.IN: Deep carbon: past to present, Orcutt, Daniel, Dasgupta eds., pp. 89-128.Mantlegeodynamics

Abstract: The science of studying diamond inclusions for understanding Earth history has developed significantly over the past decades, with new instrumentation and techniques applied to diamond sample archives revealing the stories contained within diamond inclusions. This chapter reviews what diamonds can tell us about the deep carbon cycle over the course of Earth’s history. It reviews how the geochemistry of diamonds and their inclusions inform us about the deep carbon cycle, the origin of the diamonds in Earth’s mantle, and the evolution of diamonds through time.
DS202001-0039
2020
Jacobsen, S.D.Shirey, S.B., Smit, K.V., Pearson, D.G., Walter, M.J., Aulbach, S., Brenker, F.E., Bureau, H., Burnham, A.D., Cartigny, P., Chacko, T., Frost, D.J., Hauri, E.H., Jacob, D.E., Jacobsen, S.D., Kohn, S.C., Luth, R.W., Mikhail, S., Navon, O., Nestola, F., NimDiamonds and mantle geodynamics of carbon: IN: Deep Carbon: past to present. Editors Orcutt, Danielle, Dasgupta, pp. 89-128.Mantlegeodynamics

Abstract: The science of studying diamond inclusions for understanding Earth history has developed significantly over the past decades, with new instrumentation and techniques applied to diamond sample archives revealing the stories contained within diamond inclusions. This chapter reviews what diamonds can tell us about the deep carbon cycle over the course of Earth’s history. It reviews how the geochemistry of diamonds and their inclusions inform us about the deep carbon cycle, the origin of the diamonds in Earth’s mantle, and the evolution of diamonds through time.
DS202107-1128
2019
Jacobsen, S.D.Shirey, S.B., Smit, K.V., Pearson, D.G., Walter, M.J., Aulbach, S., Brenker, F.E., Bureau, H., Burnham, A.D., Cartigny, P., Chacko, T., Frost, D.J., Hauri, E.H., Jacob, D.E., Jacobsen, S.D., Kohn, S.C., Luth, R.W., Mikhail, S., Navon, O.. Nestola, F., NimDiamonds and mantle geodynamics of carbon.Deep Carbon - Cambridge University Press , Cambridge.org 40p. PdfMantlecarbon
DS200412-0894
2004
Jacobsen, S.R.Jacobsen, S.R., Kellogg, J.B., O'Connell, R.J.Isotopic heterogeneity in the mantle: in search of the final explanation.Geochimica et Cosmochimica Acta, 13th Goldschmidt Conference held Copenhagen Denmark, Vol. 68, 11 Supp. July, ABSTRACT p.A552.MantleGeochronology
DS2002-1109
2002
Jacobshagen, V.Muller, J.P., Kley, J., Jacobshagen, V.Structure and Cenozoic kinematics of the Eastern Cordillera, southern BoliviaTectonics, Vol. 21, No. 5, 10.1029/2001TC001340.BoliviaTectonics - structure
DS2001-0522
2001
Jacobson, C.E.Jacobson, C.E.Using Auto CAD for descriptive geometry exercisesComputers and Geosciences, Vol. 27, No. 1, Feb. pp. 9-15.GlobalComputer - AutoCAD.
DS1940-0182
1948
Jacobson, D.Jacobson, D.Maize Turns to GoldCape Town: Harold Timmins, South AfricaKimberlite, Kimberley, Janlib, Gold
DS1986-0393
1986
Jacobson, D.Jacobson, D.The price of diamonds. ( reprint of 1957 novel)Johannesburg, distributed by Frank Thorold Africana Bookseller, 256p. approx. $ 12.95R.South AfricaHistory
DS1995-1049
1995
Jacobson, E.Lamorey, G., Jacobson, E.Estimation of semivariogram parameters and evaluation of the effects ofdat a sparcityMathematical Geology, Vol. 27, No. 3, pp. 327-358GlobalGeostatistics, Jackknife kriging
DS202102-0185
2020
Jacobson, N.S.Fegley, B., Lodders, K., Jacobson, N.S.Volatile element chemistry during accretion of the Earth.Geochemistry, Vol. 80, doi.org/10.1016/ j.chemer. 2019.125594 40p. PdfMantlegeochemistry

Abstract: We review some issues relevant to volatile element chemistry during accretion of the Earth with an emphasis on historical development of ideas during the past century and on issues we think are important. These ideas and issues include the following: (1) whether or not the Earth accreted hot and the geochemical evidence for high temperatures during its formation, (2) some chemical consequences of the Earth’s formation before dissipation of solar nebular gas, (3) the building blocks of the Earth, (4) the composition of the Earth and its lithophile volatility trend, (5) chemistry of silicate vapor and steam atmospheres during Earth’s formation, (6) vapor - melt partitioning and possible loss of volatile elements, (7) insights from hot rocky extrasolar planets. We include tabulated chemical kinetic data for high-temperature elementary reactions in silicate vapor and steam atmospheres. We finish with a summary of the known and unknown issues along with suggestions for future work.
DS1994-0264
1994
Jacobson, R.S.Carlson, R.L., Jacobson, R.S.Comment on Upper Crustal structure as a function of plate age... by Houtzand EwingJournal of Geophysical Research, Vol. 99, No. B 2, February 10, pp. 3135-3138MantleStructure
DS201604-0600
2016
Jacobson, S.De Vries, J., Nimmo, F., Melosh, H., Jacobson, S., Morbidelli, A., Rubie, D.Impact induced melting during accretion of the Earth.Progress in Earth and Planetary Science, Vol. 3, 7p.MantleMelting

Abstract: Because of the high energies involved, giant impacts that occur during planetary accretion cause large degrees of melting. The depth of melting in the target body after each collision determines the pressure and temperature conditions of metal-silicate equilibration and thus geochemical fractionation that results from core-mantle differentiation. The accretional collisions involved in forming the terrestrial planets of the inner Solar System have been calculated by previous studies using N-body accretion simulations. Here we use the output from such simulations to determine the volumes of melt produced and thus the pressure and temperature conditions of metal-silicate equilibration, after each impact, as Earth-like planets accrete. For these calculations a parameterised melting model is used that takes impact velocity, impact angle and the respective masses of the impacting bodies into account. The evolution of metal-silicate equilibration pressures (as defined by evolving magma ocean depths) during Earth’s accretion depends strongly on the lifetime of impact-generated magma oceans compared to the time interval between large impacts. In addition, such results depend on starting parameters in the N-body simulations, such as the number and initial mass of embryos. Thus, there is the potential for combining the results, such as those presented here, with multistage core formation models to better constrain the accretional history of the Earth.
DS201603-0433
2016
Jacobson, S.A.Young, E.D., Kohl, I.E., Warren, P.H., Rubie, D.C., Jacobson, S.A., Morbidelli, A.Oxygen isotopic evidence for vigorous mixing during the moon forming giant impact.Science, Vol. 6272, pp. 493-496.MantleMeteorite

Abstract: Earth and the Moon are shown here to have indistinguishable oxygen isotope ratios, with a difference in ?'17O of -1 ± 5 parts per million (2 standard error). On the basis of these data and our new planet formation simulations that include a realistic model for primordial oxygen isotopic reservoirs, our results favor vigorous mixing during the giant impact and therefore a high-energy, high-angular-momentum impact. The results indicate that the late veneer impactors had an average ?'17O within approximately 1 per mil of the terrestrial value, limiting possible sources for this late addition of mass to the Earth-Moon system.
DS201804-0704
2018
Jacoby, M.Jacoby, M.Carbonate mineral forms diamond on its own. New geological mechanism involving carbonate suggests Earth's lower mantle may be rich in diamond.cen.acs.org, Mar. 5, 1p.Mantlemeteorite

Abstract: When a meteorite slammed into Earth some 50,000 years ago, forming the bowl-shaped Xiuyan crater in northeast China, it left a treasure trove of geochemical research goodies. By applying microscopy and spectroscopy methods to analyze carbonate minerals found there, researchers have uncovered samples of diamond and a new mechanism for its formation.
DS2001-0523
2001
Jacoby, W.Jacoby, W.Mantle plumesJournal of Geodynamics, Vol. 32. No. 1-2, pp. 287-8.MantleHotspots
DS1999-0745
1999
Jacoby, W.R.Trubitsyn, V.P., Rykov, V.V., Jacoby, W.R.A self consistent 2 D model for the dip angle of mantle downflow beneath an overriding continent.Journal of Geodynamics, Vol. 28, No. 2-3, Sept. 2, pp. 215-224.MantleGeophysics - seismics, Subduction
DS200512-0943
2005
Jacome, M.I.Schmitz, M., Martins, A., Izarra, C., Jacome, M.I., Sanchez, J., Rocabado, V.The major features of the crustal structure in northeastern Venezuela from deep wide angle seismic observations and gravity modelling.Tectonophysics, Vol. 399, 1-4, April 27, pp. 109-124.South America, VenezuelaGeophysics - seismics, crustal structure, tectonics
DS201912-2790
2019
Jacq, K.Jacq, K., Giguet-Covex, C., Sabatier, P., Perrette, Y., Fanget, B., Coquin, D., Debret, M., Arnaud, F.High resolution grain size distribution of sediment core with hyperspectral imaging. ( not specific to diamond)Sedimentary Geology, Vol. 393-394, pdfGlobalhyperspectral

Abstract: The study of sediment cores allows for the reconstruction of past climate and environment through physical-chemical analysis. Nevertheless, this interpretation suffers from many drawbacks that can be overcome with the newest technologies. Hyperspectral imaging is one of these and allows a fast, high resolution, and non-destructive analysis of sediment cores. In this study, we use visible and near-infrared hyperspectral imaging to predict particle size fractions and distribution (PSD) at a resolution of 200?µm on a previously well-studied sediment core taken from Lake Bourget (Western Alps, France). These predictions agree with previous studies on this core. Then, the PSD was used to estimate sedimentary deposit sources using the PSD unmixing algorithm AnalySize. It permitted estimation of the contribution of five sources (micrite, small and large bio-induced calcite crystals, diatom frustules, detrital particles), which had previously been characterized. The spatial dimension allowed for laminae to be discretized and counted, in agreement with the age-depth model previously established. We then evaluated the particle size and spectral signatures of each of these annual laminae, hence characterizing their physico-chemical composition. These high-resolution data also allowed for estimation of the accumulation rate (cm/year) of each of the main sources in the laminated unit and inferring the trophic status and the presence of instantaneous events of the lake.
DS1991-0779
1991
Jacques, A.L.Jacques, A.L., Hall, A.E., Sheraton, J., Smith, C.B., Roksandic, Z.Peridotitic paragenesis planar octahedral diamonds from the Ellendale lamproite pipes, western AustraliaProceedings of Fifth International Kimberlite Conference held Araxa June 1991, Servico Geologico do Brasil (CPRM) Special, pp. 202-204AustraliaEllendale, Carbon isotope, Diamond morphology
DS1991-0780
1991
Jacques, A.L.Jacques, A.L., Knutson, J., Duncan, R.A review of the carbonatites of AustraliaProceedings of Fifth International Kimberlite Conference held Araxa June 1991, Servico Geologico do Brasil (CPRM) Special, pp. 205-207AustraliaMount Weld, Ponton Creek, Cummins Range, Mundine Well, Mud Tank, Redbank, Walloway
DS201412-0209
2014
Jacques, A.L.Downes, P.J., Demeny, A., Czuppon, G., Jacques, A.L., Verrall, M., Sweetapple, M., Adams, D., McNaughton, N.J., Gwalani, L.G., Griffin, B.J.Stable H-C-O isotope and trace element geochemistry of the Cummins Range carbonatite complex, Kimberley region Western Australia: implications for hydrothermal REE mineralization, carbonatite evolution and mantle source regions.Mineralium Deposita, in press available 28p.AustraliaCarbonatite
DS202001-0021
2019
Jacques, J.F.Jacques, J.F.An eye on diamonds. The way diamonds are utilised for ophthalmic surgery.Gems & Jewellery, Vol. 28, 4, pp. 22-23.GlobalCryo-EM
DS201708-1677
2017
Jacques, L.Jacques, L.Insights into the petrogenesis of the West Kimberley lamproites from trace elements in olivine.11th. International Kimberlite Conference, OralAustralialamproites
DS201710-2245
2017
Jacquet, B.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.
DS1860-1033
1898
Jacquet, J.B.Jacquet, J.B.Diamonds. In: Appendix No. 12New South Wales Geological Survey Report For 1897, P. 172.Australia, New South WalesDiamond Occurrence
DS1920-0387
1928
Jacquier, G.Jacquier, G.The Formation of Diamonds. Some Theories and Facts According to the Great French Mineralogist H. Moissan.Min. Ind. Magazine (johannesburg), Vol. 7, Dec. 26TH. PP. 413-415.GlobalDiamond Genesis
DS201412-0419
2014
Jacubek, J.Jacubek, J.From dream to reality …. Is it a mine?SRK and Friends Diamond Short Course, March 1, ppt p. 172-208.TechnologyMining methods
DS201906-1345
2019
Jadamec, M.Saylor, J.E., Finzel, E., Jadamec, M.Linking observations and modeling of flat-slab subduction. EOS.100, doi.org/10.1029/ 2019/EO122245United States, Montanasubduction
DS201611-2114
2016
Jadamec, M.A.Jadamec, M.A.Insights into slab-driven mantle flow from advances in three-dimensional modelling.Journal of Geodynamics, Vol. 100, pp. 51-70.MantleSubduction

Abstract: The wealth of seismic observations collected over the past 20 years has raised intriguing questions about the three-dimensional (3D) nature of the mantle flow field close to subduction zones and provided a valuable constraint for how the plate geometry may influence mantle flow proximal to the slab. In geodynamics, there has been a new direction of subduction zone modelling that has explored the 3D nature of slab-driven mantle flow, motivated in part by the observations from shear wave splitting, but also by the observed variations in slab geometries worldwide. Advances in high-performance computing are now allowing for an unprecedented level of detail to be incorporated into numerical models of subduction. This paper summarizes recent advances from 3D geodynamic models that reveal the complex nature of slab-driven mantle flow, including trench parallel flow, toroidal flow around slab edges, mantle upwelling at lateral slab edges, and small scale convection within the mantle wedge. This implies slab-driven mantle deformation zones occur in the asthenosphere proximal to the slab, wherein the mantle may commonly flow in a different direction and rate than the surface plates, implying laterally variable plate-mantle coupling. The 3D slab-driven mantle flow can explain, in part, the lateral transport of geochemical signatures in subduction zones. In addition, high-resolution geographically referenced models can inform the interpretation of slab structure, where seismic data are lacking. The incorporation of complex plate boundaries into high-resolution, 3D numerical models opens the door to a new avenue of research in model construction, data assimilation, and modelling workflows, and gives 3D immersive visualization a new role in scientific discovery.
DS201710-2242
2017
Jadamec, M.A.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.
DS201801-0026
2017
Jadhav, G.N.Jadhav, G.N., Viladkar, S.G., Goswami, R., Badhe, K.Fluid melt inclusions petrography of primary calcites from carbonatites of Amba Dongar, Gujarat India.Carbonatite-alkaline rocks and associated mineral deposits , Dec. 8-11, abstract p. 15.Indiadeposit - Amba Dongar

Abstract: The Amba Dongar Carbonatite complex consists of sovites which are dominantly composed of calcite along with pyrochlore, phlogopite, apatite, barite, ankerite and haematite and minor opaques such as magnetite, chalcopyrite and pyrite. Two distinct types of texture are present in these carbonatites- a mosaic of equigranular calcite crystals and porphyritic texture. Silicate melt inclusions are observed in primary minerals viz. apatite and calcites. These are small droplets of silicate melt entrapped during the growth of the minerals. In this case carbonatite-alkaline silicate melt inclusions are entrapped predominantly in calcite crystals. Dominantly these calcite host minerals are predominantly containing fluid inclusions along with halite, sylvite and minor nahcolite as daughter crystals. The presence of calcite with nahcolite indicates the coexistence of a Ca-rich, alkali-bearing carbonatite melt phase. The melt inclusions are heated upto 1100 °C and the carbonate melt inclusions appear to be homogenized around 950 °C. This fall within the range of melting temperature of a carbonatite melt. In addition to these, three types of fluid inclusions were also observed in host calcite they are i) monophase, ii) biphase and iii) polyphase types of fluid inclusions. The fluid inclusions contain CO2 gas, Li-K carbonate phases and fergusonite based on Micro-Laser- Raman. Carbon dioxide is the dominant gas phase in most of the fluid inclusions, indicating high temperature and deep mantle source(?). The fluid inclusions have formed from a primary mother liquor that has separated out from the early formed carbonatitic melt. This fluid was either formed just after the formation of melt inclusions or during simultaneous crystallization from a carbonatitic or to be more precise carbonatiticpegmatite melt(?).The presence of both melt and fluid inclusions in these primary calcite host minerals indicates the presence of a carbonatitic-pegmatitic fluid, which must have got separated out from the early formed carbonatite-alkaline silicate magma.
DS1991-1496
1991
Jadhav, P.C.Sant, D.A., Karanth, R.V., Jadhav, P.C.A note on the occurrence of carbonatite dykes in the Lower Narmada ValleyJournal of Geological Society India, Vol. 37, Feb. pp. 119-127IndiaCarbonatite, Petrology
DS1970-0318
1971
Jadia, P.L.Jadia, P.L.Preparation of Diamond Roughs for the MarketIndia Geological Survey Miscellaneous Publishing, No. 19, PP. 203-207.IndiaMineral Economics
DS1970-0319
1971
Jadia, P.L.Jadia, P.L.Diamondiferous Alluvials of RamkheriaIndia Geological Survey Miscellaneous Publishing, No. 19, PP. 86-91.IndiaSampling, Prospecting, Alluvial Placer Deposits
DS1995-1317
1995
Jaeckel, P.Munyanyiwa, H., Kroner, A., Jaeckel, P.uranium-lead (U-Pb) and lead lead single zircon ages for the chrno-enderbites from the Magondimobile beltSouth African Journal of Geology, Vol. 98, No. 1, March pp. 52-57ZimbabweGeochronology, Magondi belt
DS1996-1033
1996
JaegerNewsom, 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
DS1920-0340
1927
Jaeger, F.Jaeger, F.Die Diamantenwueste SuedwestafrikasZeitschr. Geogr. (leipzig), Vol. 33, PP. 321-329.Southwest Africa, NamibiaGeology, Geomorphology
DS200612-0839
2006
Jaeger-Frank, E.Ludascher, B., Lin, K., Bowers, S., Jaeger-Frank, E., Brodaric, B., Baru, C.Managing scientific dat a: from dat a integration to scientific workflows.In: Sinha, A.K. Geoinformatics: data to knowledge, GSA Special Paper, 397, 397,pp.109-30TechnologyData - not specific to diamonds
DS201012-0318
2010
Jaesok, L.Jaesok, L., Haemycong, J.Lattice preferred orientation of olivine in garnet peridotites from Finsch, South Africa.International Mineralogical Association meeting August Budapest, abstract p. 216.Africa, South AfricaSpectroscopy
DS202004-0500
2020
Jaffal, M.Ba, M.H., Ibough, H., Lo, K., Youbi, N., Jaffal, M., Ernst, R.E., Niang, A.J., Dia, I., Abdeina, E.H., Bensalah, M.K., Boumehdi, M.A., Soderlund, U.Spatial and temporal distribution patterns of Precambrian mafic dyke swarms in northern Mauritania ( West African Craton): analysis and results fro remote sensing interpretation, geographical information systems ( GIS), Google Earth TM images, and regionaArabian Journal of Geosciences, Vol. 13, , 209 orchid.org/ 0000-002-3287-9537Africa, Mauritaniacraton

Abstract: We used remote sensing, geographical information systems, Google Earth™ images, and regional geology in order to (i) improve the mapping of linear structures and understand the chronology of different mafic dyke swarms in the Ahmeyim area that belongs to the Archean Tasiast-Tijirit Terrane of the Reguibat Shield, West African craton, NW Mauritania. The spatial and temporal distributions with the trends of the dyke swarms provide important information about geodynamics. The analysis of the mafic dyke swarms map and statistical data allow us to distinguish four mafic dyke swarm sets: a major swarm trending NE-SW to NNE-SSW (80%) and three minor swarms trending EW to ENE-WSW (9.33%), NW-SE to WNW-ESE (9.06%), and NS (1.3%). The major swarms extend over 35 km while the minor swarms do not exceed 13 km. The Google Earth™ images reveal relative ages through crossover relationships. The major NE-SW to NNE-SSW and the minor NS swarms are the oldest generations emplaced in the Ahemyim area. The NW-SE-oriented swarm dykes which are cutting the two former swarms are emplaced later. The minor E-W to WSW-ENE swarms are probably the youngest. A precise U-Pb baddeleyite age of 2733?±?2 Ma has been obtained for the NNE-SSW Ahmeyim Great Dyke. This dyke is approximately 1500 m wide in some zone and extends for more than 150 km. The distinct mafic dyke swarms being identified in this study can potentially be linked with coeval magmatic events on other cratons around the globe to identify reconstructed LIPs and constrain continental reconstructions.
DS201810-2338
2018
Jaffri, S.H.Khanna, T.C., Sesha Sai, V.V., Jaffri, S.H., Keshav Krishna, A., Korakoppa, M.M.Boninites in the ~3.3 Ga Holenarsipur greenstone belt, western Dharwar Craton, India.MDPI Geosciences, Researchgate 17p.Indiaboninites

Abstract: In this contribution, we present detailed field, petrography, mineral chemistry, and geochemistry of newly identified high-Si high-Mg metavolcanic rocks from the southern part of the ~3.3 Ga Holenarsipur greenstone belt in the western Dharwar craton, India. The rocks occur as conformable bands that were interleaved with the mafic-ultramafic units. The entire volcanic package exhibits uniform foliation pattern, and metamorphosed under greenschist to low grade amphibolite facies conditions. The rocks are extremely fine grained and exhibit relict primary igneous textures. They are composed of orthopyroxene and clinopyroxene phenocrysts with serpentine, talc, and amphibole (altered clinopyroxene). Cr-spinel, rutile, ilmenite, and apatite occur as disseminated minute grains in the groundmass. The mineralogical composition and the geochemical signatures comprising of high SiO2 (~53 wt. %), Mg# (~83), low TiO2 (~0.18 wt. %), and higher than chondritic Al2O3/TiO2 ratio (~26), reversely fractionated heavy rare earth elements (REE) (GdN/YbN ~ 0.8), resulting in concave-up patterns, and positive Zr anomaly, typically resembled with the Phanerozoic boninites. Depletion in the high field strength elements Nb, and Ti relative to Th and the REE in a primitive mantle normalized trace element variation diagram, cannot account for contamination by pre-existing Mesoarchean continental crust present in the study area. The trace element attributes instead suggest an intraoceanic subduction-related tectonic setting for the genesis of these rocks. Accordingly, the Holenarsipur high-Si high-Mg metavolcanic rocks have been identified as boninites. It importantly indicates that the geodynamic process involved in the generation of Archean boninites, was perhaps not significantly different from the widely recognized two-stage melt generation process that produced the Phanerozoic boninites, and hence provides compelling evidence for the onset of Phanerozoic type plate tectonic processes by at least ~3.3 Ga, in the Earth’s evolutionary history.
DS201012-0319
2010
Jafri, S.S.H.Jafri, S.S.H., Moeen, S., Dayal, A.M., Narayana, B.L.High silica lamproite dykes from Schirmacher Oasis, Queen Maud Land, Antarctica.International Dyke Conference Held Feb. 6, India, 1p. AbstractAntarcticaLamproite
DS1989-1078
1989
Jagannadha Rao, S.Murthy Radhakrishna, I.V., Jagannadha Rao, S.A fortran 77 program for inverting gravity anomalies of two dimensional basement structuresComputers and Geosciences, Vol. 15, No. 7, pp. 1149-1156. Database #18197GlobalGeophysics, Tectonics basement structure, Computer- program Fortran 77
DS1993-0731
1993
Jagannadha Rao, S.Jagannadha Rao, S., et al.Automatic inversion of self-potential anomalies of sheet-like bodiesComputers and Geosciences, Vol. 19, No. 1, pp. 61-73IndiaGeophysics -Special Paper, Sulphides, graphite, computer applications
DS2003-0538
2003
Jagger, K.Hamblin, A.P., Stasiuk, L.D., Sweet, L.D., Lockhart, G., Dyck, D.R., Jagger, K.Post kimberlite Eocene strat a in Crater Basin, Lac de Gras, Northwest Territories8ikc, Www.venuewest.com/8ikc/program.htm, Session 1 POSTER abstractNorthwest TerritoriesKimberlite geology and economics, Stratigraphy
DS200712-0478
2007
Jaglinski, T.Jaglinski, T., Kochmann, D., Stone, D., Lakes, R.S.Composite materials with viscoelastic stiffness greater than diamond.Science, No. 5812, Feb. 2, pp. 620-621.TechnologyChemistry
DS1860-0468
1885
Jagnaux, R.Jagnaux, R.Traite Mineralogie Applique Aux Arts l'industrie....Paris: Octave Doin., 883P.GlobalMineralogy
DS2003-0637
2003
Jago, B.Jago, B.Diamond sample processing and dat a interpretationSme Annual Meeting, February 24-26, ( Brief Abstract), 1/8p.GlobalNews item, Technology
DS1980-0182
1980
Jago, B.C.Jago, B.C.Geology of a Portion of the Western Contact Margin, the Coldwell Complex.Bsc. Thesis, Lakehead University, Canada, OntarioAlkaline Rocks, Carbonatite
DS1982-0294
1982
Jago, B.C.Jago, B.C.Mineralogy and Petrology of the Ham Kimberlite, Somerset Island, Northwest Territories, Canada.Thunder Bay: Msc. Thesis, Lakehead University, 235P.Canada, Northwest Territories, Batty BayGarnet, Geothermometry, Geobarometry, Geophysics, Geochemistry
DS1985-0305
1985
Jago, B.C.Jago, B.C., Mitchell, R.H.Mineralogy and petrology of the Ham kimberlite Somerset IslandNorthwestTerritoriesCanadian Mineralogist, Vol. 23, pp. 619-634Northwest TerritoriesBlank
DS1986-0394
1986
Jago, B.C.Jago, B.C., Mitchell, R.H.The statistical classification of kimberlite garnet by devisive cluster analysis and multiple discriminant analysisProceedings of the Fourth International Kimberlite Conference, Held Perth, Australia, No. 16, pp. 42-44Northwest TerritoriesSomserset Island, Geochemistry
DS1987-0315
1987
Jago, B.C.Jago, B.C., Mitchell, R.H.Ultrabasic xenoliths from the Ham kimberlite, Somerset Island,NorthwestTerritoriesCanadian Mineralogist, Vol. 25, pt. 3 September pp. 515-525Northwest TerritoriesGeothermobarometry
DS1987-0316
1987
Jago, B.C.Jago, B.C., Mitchell, R.H.A new garnet classification technique: divisive cluster analysis applied to garnet populations from Somerset Island kimberlites #2Fourth International Kimberlite Conference, In pressNorthwest TerritoriesSomerset Island, Garnet
DS1989-0515
1989
Jago, B.C.Gittins, J., Jago, B.C.Calcitic carbonatite lavas reinterpreted; their significance for magmagenesisNew Mexico Bureau of Mines Bulletin., Continental Magmatism Abstract Volume, Held, Bulletin. No. 131, p. 108. AbstractGlobalCarbonatite
DS1989-0695
1989
Jago, B.C.Jago, B.C., Mitchell, R.H.A new garnet classification technique: divisive cluster analysis applied to garnet populations from Somerset Island kimberlites #1Geological Society of Australia Inc. Blackwell Scientific Publishing, Special, No. 14, Vol. 1, pp. 297-310Northwest Territories, Somerset IslandAnalysis, Garnets
DS1990-0574
1990
Jago, B.C.Gittins, J., Beckett, M.F., Jago, B.C.Composition of the fluid phase accompanying carbonatite magma: a criticalexaminationAmerican Mineralogist, Vol. 75, No. 9-10. Sept.-Oct. pp. 1106-1109QuebecOka, Husereau Hill, Carbonatite
DS1990-0575
1990
Jago, B.C.Gittins, J., Jago, B.C.Carbonatite lavas: the role of fluorine, chlorine and water in carbonatitemagmasTerra, Abstracts of Experimental mineralogy, petrology and, Vol. 2, December abstracts p. 76GlobalCarbonatite, Experimental petrology
DS1990-0751
1990
Jago, B.C.Jago, B.C., Gittins, J.Comparative roles of fluorine and water in carbonatite magma evolutionTerra, Abstracts of Experimental mineralogy, petrology and, Vol. 2, December abstracts p. 82GlobalExperimental Petrology, Carbonatite
DS1991-0578
1991
Jago, B.C.Gittins, J., Jago, B.C.Extrusive carbonatites: their origins reappraised in the light of new experimental dataGeological Magazine, Vol. 128, No. 4, July pp. 301-305GlobalExperimental petrology, Carbonatite
DS1991-0781
1991
Jago, B.C.Jago, B.C.The role of fluorine in the evolution of alkali-bearing carbonatite magma sand the formation of carbonatite-hosted apatite and pyrochlore depositsPh.d. thesis University of Toronto, 410p, MantleGeochemistry, Carbonatite
DS1991-0782
1991
Jago, B.C.Jago, B.C., Gittins, J.The role of fluorine in the crystallization of niobium and phosphorous ores in carbonatitesProceedings of Fifth International Kimberlite Conference held Araxa June 1991, Servico Geologico do Brasil (CPRM) Special, pp. 193-195GlobalPyrochlore, apatite, Experimental petrology
DS1991-0783
1991
Jago, B.C.Jago, B.C., Gittins, J.The role of fluorine in carbonatite magma evolutionNature, Vol. 349, No. 6304, January 3, pp. 56-58TanzaniaCarbonatite, Oldoinyo Lengai -fluorine
DS1992-0576
1992
Jago, B.C.Gittins, J., Beckett, M.F., Jago, B.C.Composition of the fluid phase accompanying carbonatite magmas: acritical examination- replyAmerican Mineralogist, Vol. 77, No. 5, 6, May-June pp. 666-667GlobalCarbonatite, Petrology
DS1992-0577
1992
Jago, B.C.Gittins, J., Jago, B.C.The role of fluorine in the crystallization and evolution of carbonatitemagmasEos Transactions, Vol. 73, No. 14, April 7, supplement abstracts p.349GlobalCarbonatite, Fluorine
DS1993-0732
1993
Jago, B.C.Jago, B.C.Petrology and mineralogy of kimberlite and diamond indicator mineralsQuebec Exploration Conference summaries held September 15-1th. Val d'Or, pp. 3-5GlobalBrief overview petrology
DS1993-0733
1993
Jago, B.C.Jago, B.C.The tentative field identification of kimberlite and what should happennext: a short course definition, classification, petrology, mineralogy andprelim. eval. evalPreprint from author, 34pGlobalKimberlite, Field identification notes
DS1993-0734
1993
Jago, B.C.Jago, B.C., Gittins, J.Pyrochlore crystallization in carbonatites: the role of fluorineSouth African Journal of Geology, Vol. 96, No. 3, Sept. pp. 149-159.TanzaniaCarbonatite -pyrochlore, Petrology -experimental
DS1994-0823
1994
Jago, B.C.Jago, B.C., Gittins, J.Solubility of water in carbonatite magmas and partitioning of Fluorine and Chlorine between magma and aequeous fluid.Geological Association of Canada (GAC) Abstract Volume, Vol. 19, p.GlobalCarbonatite, Petrology -experimental
DS1998-0515
1998
Jago, B.C.Gittins, J., Jago, B.C.Differentiation of natrocarbonatite magma at Oldoinyo Lengai volcano, Tanzania.Mineralogical Magazine, Vol. 62, No. 6, Dec. 1, pp. 759-68.TanzaniaCarbonatite, Deposit - Oldoinyo Lengai
DS1999-0331
1999
Jago, B.C.Jago, B.C., Gittins, J.Manganese and Fluorine bearing rasvumite in natrocarbonatite at Oldoinyo Lengai Tanzania.Mineralogical Magazine, Vol. 63, No. 1, pp. 53-5.TanzaniaCarbonatite, Deposit - Oldoinyo Lengai
DS2000-0439
2000
Jago, B.C.Jago, B.C.Mineralogy and microdiamonds - diamond exploration toolsSociety for Mining, Metallurgy and Exploration (SME) preprint, Feb. 27GlobalDiamond - technology - microdiamonds
DS2001-0524
2001
Jago, B.C.Jago, B.C.Mineralogy and microdiamonds - evaluating a diamond prospectOntario Geological Survey, Northeastern Mineral Symposium, p.12-3, abstract.Ontario, WawaSampling - analyses
DS2002-0758
2002
Jago, B.C.Jago, B.C., Davis, D., Derbuch, H.Diamonds on the Brodeur Peninsula - a new kimberlite province in Nunuvut, CanadaC.i.m. Bulletin, Vol. 95, No. 1061, May, pp. 72-78.Nunavut, Brodeur Peninsula, Baffin IslandGeology, geophysics, petrology, mineralogy, Deposit - Freightrain
DS2003-0638
2003
Jago, B.C.Jago, B.C., Davis, D., Derbuch, H.Diamond indicator mineral chemistry in relation to diamond potential - the Brodeur31st Yellowknife Geoscience Forum, p. 44-5. (abst.Nunavut, Brodeur Peninsula, Somerset IslandMineral chemistry
DS2003-0639
2003
Jago, B.C.Jago, B.C., Lindsay, J., De Belder, D., Davis, D.W.Diamond grade and quality in relation to mineral chemistry of Twin Mining's Jackson31st Yellowknife Geoscience Forum, p. 46. (abst.Nunavut, Brodeur PeninsulaMineral chemistry
DS200412-0895
2003
Jago, B.C.Jago, B.C., Davis, D., Derbuch, H.Diamond indicator mineral chemistry in relation to diamond potential - the Brodeur Peninsula kimberlite province vs Somerset isl31st Yellowknife Geoscience Forum, p. 44-5. (abst.Canada, Nunavut, Brodeur Peninsula, Somerset IslandMineral chemistry
DS200412-0896
2003
Jago, B.C.Jago, B.C., Lindsay, J., De Belder, D., Davis, D.W.Diamond grade and quality in relation to mineral chemistry of Twin Mining's Jackson In let FreightTrain kimberlite, Brodeur Penin31st Yellowknife Geoscience Forum, p. 46. (abst.Canada, Nunavut, Brodeur PeninsulaMineral chemistry
DS201112-0473
1982
Jago, B.C.Jago, B.C.Mineralogy and petrology of the Ham kimberlite, Somerset Island, N.W.T. Canada.Thesis: Msc. Lakehead University, Canada, Northwest TerritoriesThesis - note availability based on request to author
DS1986-0751
1986
JagoutzSmith, C.B., Allsopp, H.L., Kramers, J.D., Gurney, J.J., JagoutzIsotopic and geochemical studies of kimberlitic and included xenolithsProceedings of the Fourth International Kimberlite Conference, Held Perth, Australia, No. 16, pp. 329-331South Africa, BotswanaBlank
DS2000-0886
2000
JagoutzShatskii, V.S., Simonov, Jagoutz, Kozmenko, KurenkovNew dat a on the age of eclogites from the Polar UralsDoklady Academy of Sciences, Vol. 371a, No. 3, Mar-Apr. pp. 534-8.Russia, UralsEclogites, Geochronology
DS1983-0328
1983
Jagoutz, E.Jagoutz, E., Spettel, B., Waenke, H., Dawson, B.Identification of Early Differentiation Processes on the Earth.Meteoritics, Vol. 18, No. 4, PP. 319-320. (abstract.).GlobalGeochemistry, Kimberlite, Ultramafics
DS1984-0375
1984
Jagoutz, E.Jagoutz, E., Dawson, J.B., Hoernes, S., Spettel, B., Waenke, H.Anorthositic Oceanic Crust in the Archean EarthLunar and Planetary Science Conference 15th. Abstract Volume, Vol. 15, pp. 395-396GlobalAnorthosite
DS1986-0395
1986
Jagoutz, E.Jagoutz, E.samarium-neodymium (Sm-Nd) systematics in eclogites from SiberiaProceedings of the Fourth International Kimberlite Conference, Held Perth, Australia, No. 16, pp. 265-266RussiaEclogite
DS1986-0708
1986
Jagoutz, E.Schier, D., Jagoutz, E.Cerium isotopes- new aspects for kimberlite genesis by a newisotopicsystemProceedings of the Fourth International Kimberlite Conference, Held Perth, Australia, No. 16, pp. 318-319South AfricaBlank
DS1987-0689
1987
Jagoutz, E.Smith, C.B., Kramers, J.D., Jagoutz, E.Subcalcic megacrysts in kimberlite: deep lithosphere orasthenosphereorigins?Terra Cognita, Conference abstracts Oceanic and Continental Lithosphere:, Vol. 7, No. 4, Autumn, abstract only p. 624South AfricaBlank
DS1988-0323
1988
Jagoutz, E.Jagoutz, E.neodymium and Strontium systematics in an eclogite xenolith from Tanzania:evidence for frozen mineral equilibration temperatures in the continentallithosphereGeochimica et Cosmochimica Acta, Vol. 52, No. 5, May pp. 1285-194TanzaniaBlank
DS1988-0784
1988
Jagoutz, E.Zindler, A., Jagoutz, E.Mantle cryptologyGeochimica et Cosmochimica Acta, Vol. 52, No. 2, February pp. 319-333GlobalBlank
DS1989-0696
1989
Jagoutz, E.Jagoutz, E., Shatsky, V.S., Sobolev, N.V., Pokhilenko, N.P.lead-neodymium-Sr isotope study of the Kokchetav Massif;the outcrop of the lowerlithosphereDiamond Workshop, International Geological Congress, July 15-16th. editors, pp. 32-35. AbstractRussiaMantle, Geochronology
DS1990-0752
1990
Jagoutz, E.Jagoutz, E., Shatsky, V.S., Sobolev, N.V.Sr-Neodymium-Palladium isotopic study of ultra high pressuret rocks from Kokchetav massifEos, Vol. 71, No. 43, October 23, p. 1707 AbstractRussiaMetamorphic rocks, Diamonds
DS1990-1341
1990
Jagoutz, E.Shatskii, V.S., Jagoutz, E., Sobolev, N.V., Kozmenko, O.A.Geochemical characteristics of crustal rocks subducted into the uppermantleEos, Vol. 71, No. 43, October 23, p. 1707 AbstractRussiaMetamorphic rocks, Diamonds
DS1991-0638
1991
Jagoutz, E.Guther, M., Jagoutz, E.Systematics of isotopic disequilibration temperatures between minerals of low temperature garnet lherzolitesProceedings of Fifth International Kimberlite Conference held Araxa June 1991, Servico Geologico do Brasil (CPRM) Special, pp. 122-124South AfricaGeochronology -isotopes
DS1991-0777
1991
Jagoutz, E.Jacob, D., Jagoutz, E., Sobolev, N.V.A diamond graphite bearing eclogitic xenolith from Roberts Victor-indication for petrogenesis from lead, neodymium, and Sr isotopesProceedings of Fifth International Kimberlite Conference held Araxa June 1991, Servico Geologico do Brasil (CPRM) Special, pp. 190-192South AfricaGeochronology, Geochemistry
DS1991-0925
1991
Jagoutz, E.Kovalenko, V.I., Ionov, D.A., Yarmolyuk, V.V., Jagoutz, E.Isotope dat a on the evolution of the mantle and its correlation with the evolution of the crust in some parts of central AsiaGeochemistry International, Vol. 28, No. 4, pp. 82-92China, RussiaMantle, Geochronology
DS1992-0768
1992
Jagoutz, E.Jagoutz, E.Isotopic systematics of ultra high pressureT rocksProceedings of the 29th International Geological Congress. Held Japan August 1992, Vol. 2, abstract p. 598RussiaDiamond, Crustal rocks
DS1993-0728
1993
Jagoutz, E.Jacob, D., Jagoutz, E., et al.Diamondiferous eclogites from Siberia: ancient oceanic crustAmerican Geophysical Union, EOS, supplement Abstract Volume, October, Vol. 74, No. 43, October 26, abstract p. 637.Russia, SiberiaEclogite
DS1993-0729
1993
Jagoutz, E.Jacob, D.E., Jagoutz, E., Sobolev, N.V.Isotopic systematics of subcalcic garnets from SiberiaEos, Transactions, American Geophysical Union, Vol. 74, No. 16, April 20, supplement abstract p. 320Russia, SiberiaGeochemistry -garnets, Geochronology
DS1993-1442
1993
Jagoutz, E.Shatsky, V.S., Jagoutz, E., Kozmenko, O.A., Blinchik, T.M., Sobolev, N.V.Age and genesis of eclogites from the Kokchetav massif (northernKazakhstan).Russian Geology and Geophysics, Vol. 34, No. 12, pp. 40-50.Russia, KazakhstanGeochronology, Eclogites
DS1994-0674
1994
Jagoutz, E.Gunther, M., Jagoutz, E.Isotopic disequilibration temperatures (Samarium/neodymium, Rubidium-Strontium) between mineral phases of coarse grained, low temperature garnet peridotites from Kimberley Floors.Proceedings of Fifth International Kimberlite Conference, Vol. 1, pp. 354-365.South AfricaPeridotites, Deposit -Kimberley Floors
DS1994-0819
1994
Jagoutz, E.Jacob, D., Jagoutz, E.A diamond graphite bearing eclogitic xenoliths from Roberts Victor (SouthAfrica) -indication for petrogenesis from lead neodymium and Sr isotopes.Proceedings of Fifth International Kimberlite Conference, Vol. 1, pp. 304-317.South AfricaGeochronology, Deposit -Roberts Victor
DS1994-0820
1994
Jagoutz, E.Jacob, D., Jagoutz, E., Lowry, D., Mattey, D., KudrjavtsevaDiamondiferous eclogites from Siberia: remnants of Archean oceanic crustGeochimica et Cosmochimica Acta, Vol. 58, 23, pp. 5191-207.Russia, SiberiaEclogites, Deposit -Udachnaya
DS1994-0821
1994
Jagoutz, E.Jacob, D.E., Jagoutz, E., Lowry, D., et al.Diamondiferous eclogites from Udachnaya: a subducted component in the Siberian upper mantle.Mineralogical Magazine, Vol. 58A, pp. 448-449. AbstractRussia, SiberiaEclogites, diamond genesis, Deposit -Udachnaya
DS1995-0442
1995
Jagoutz, E.Dreibus, G., Jagoutz, E., Wanke, H.Water in the earth's mantleProceedings of the Sixth International Kimberlite Conference Extended Abstracts, p. 141-2.MantleAccretion model -water
DS1995-0700
1995
Jagoutz, E.Gunther, M., Jagoutz, E.Age informations in kimberlite derived low temperature garnet lherzolite xenoliths -what do they mean?Terra Nova, Abstract Vol., p. 334.South AfricaXenoliths, Kimberlite
DS1995-0701
1995
Jagoutz, E.Gunther, M., Jagoutz, E.Ages and processes as reported by isotopes of kimberlite derived low temperature lherzolites.Proceedings of the Sixth International Kimberlite Conference Extended Abstracts, p. 205-7.South Africa, Russia, SiberiaGeochronology, Deposit -Kimberley Floors, Jagersfontein, Udachnaya, Mir
DS1995-0862
1995
Jagoutz, E.Jacob, D.E., Jagoutz, E., Sobolev, N.V., Sorowka, A.Isotopic analysis ( Samarium/neodymium, Rubidium-Strontium and Uranium/lead) of single subcalcic garnet grains from Yakutian kimberlites.Proceedings of the Sixth International Kimberlite Conference Abstracts, pp. 257-259.Russia, YakutiaGeochemistry, isotopes, Geochronology -garnets
DS1995-1720
1995
Jagoutz, E.Shatsky, V.S., Sobolev, N.V., Jagoutz, E., Vavilov, M.A.Ultrahigh pressure metamorphic environment of microdiamondsProceedings of the Sixth International Kimberlite Conference Abstracts, pp. 512-514.Russia, KazakhstanMetamorphic, Deposit -Kokchetav Massif
DS1997-1028
1997
Jagoutz, E.Shatsky, V.S., Jagoutz, E., Kozmenko, O.A.Sm neodymium dating of the high pressure metamorphism of the Maksyutov Complex, southern Urals.Doklady Academy of Sciences, Vol. 353, No. 2, Feb-Mar, pp. 285-8.Russia, UralsGeochronology, ultra high pressure (UHP)
DS1998-0672
1998
Jagoutz, E.Jacob, D., Jagoutz, E., Zinngrebe, E., Snyder, TaylorComment and reply on the origins of Yakutian eclogite xenolithsJournal of Petrology, Vol. 39, No. 8, Aug. 1, pp. 1527-1539.Russia, YakutiaEclogites, Diamond genesis
DS1998-0674
1998
Jagoutz, E.Jacob, D.E., Jagoutz, E., Sobolev, N.V.Neodynium and strontium isotopic measurements on single subcalcic garnet grains from Yakutian kimberlites.Neues Jahrbuch fnr Mineralogie Abh., No. 172, pp. 357-379.Russia, YakutiaGeochronology
DS1998-1246
1998
Jagoutz, E.Roden, M.F., Lazko, E.E., Jagoutz, E.Petrology and geochemistry of peridotite inclusions from the Mirkimberlite, Siberia.7th. Kimberlite Conference abstract, pp. 741-2.Russia, Siberia, YakutiaXenoliths - inclusions, Deposit - Mir
DS1999-0606
1999
Jagoutz, E.Roden, M.F., Lazko, E.E., Jagoutz, E.The role of garnet pyroxenites in the Siberian lithosphere: evidence from the Mir kimberlite.7th International Kimberlite Conference Nixon, Vol. 2, pp. 714-20.Russia, Siberia, YakutiaMineralogy, thermobarometry, mineral chemistry, analyse, Deposit - Mir
DS2003-0631
2003
Jagoutz, E.Jacob, D.E., Fung, A., Jagoutz, E., Pearson, D.G.Petrology and geochemistry of eclogite xenoliths from the Ekati kimberlite area8ikc, Www.venuewest.com/8ikc/program.htm, Session 2, POSTER abstractNorthwest TerritoriesEclogites and Diamonds, Deposit - Ekati
DS2003-0640
2003
Jagoutz, E.Jagoutz, E., Dreibus, G.On the search for 142 Nd in terrestrial rocks8 Ikc Www.venuewest.com/8ikc/program.htm, Session 4, AbstractSouth Africa, Russia, SiberiaMantle geochemistry, Lherzolitic nodules
DS2003-1175
2003
Jagoutz, E.Roden, M., Patino-Douce, A., Lazko, E., Jagoutz, E.Exsolution textures in high pressure garnets, Mir kimberlite, Sibveria8 Ikc Www.venuewest.com/8ikc/program.htm, Session 6, POSTER abstractRussia, SiberiaDeposit - Mir
DS200412-0897
2003
Jagoutz, E.Jagoutz, E., Dreibus, G.On the search for 142 Nd in terrestrial rocks.8 IKC Program, Session 4, AbstractAfrica, South Africa, Russia, SiberiaMantle geochemistry Lherzolitic nodules
DS200412-1680
2003
Jagoutz, E.Roden, M., Patino-Douce, A., Lazko, E., Jagoutz, E.Exsolution textures in high pressure garnets, Mir kimberlite, Sibveria.8 IKC Program, Session 6, POSTER abstractRussia, SiberiaMantle petrology Deposit - Mir
DS200512-0462
2005
Jagoutz, E.Ionov, D.A., Ashchepkov, I., Jagoutz, E.The provenance of fertile off craton lithospheric mantle: Sr Nd isotope chemical composition of garnet and spinel peridotite xenoliths from Vitim, Siberia.Chemical Geology, Vol. 217, 1-2, April 15, pp. 41-75.Russia, SiberiaGeochronology
DS200612-1165
2006
Jagoutz, E.Roden, M.F., Paino-Douce, A.E., Jagoutz, E., Lazko, E.E.High pressure petrogenesis of Mg rich garnet pyroxenites from Mir kimberlite, Russia.Lithos, Vol. 90, 1-2, pp. 77-91.Russia, SiberiaMajorite
DS200612-1166
2006
Jagoutz, E.Roden, M.F., PatinoDouce, A.E., Jagoutz, E., Lazko, E.E.High pressure petrogenesis of Mg rich garnet pyroxenites from Mir kimberlite, Russia.Lithos, Vol.90, 1-2, August pp. 77-91.Russia, YakutiaDeposit - Mir, petrology
DS201907-1572
2019
Jagoutz, E.Shatsky, V., Jagoutz, E., Kozmenko, O., Ragozin, A., Skuzovatov, S., Sobolev, N.The protolith nature of diamondiferous metamorphic rocks of the Kokchetav Massif.Acta Geologica Sinica, Vol. 93, 1, p. 173-Russiadeposit - Kokchetav

Abstract: International Symposium on Deep Earth Exploration and Practices Beijing, China -October24-26, 2018The protolithnatureof diamondiferous metamorphic rocks of the Kokchetav MassifVladislav Shatsky1,2,3, Emil Jagoutz4, Olga Kozmenko1, Alexey Ragozin1,3, Sergei Skuzovatov2and Nikolai Sobolev1,31Sobolev Institute of Geology and Mineralogy SB RAS, Novosibirsk, 630090, Russia, Institute of Geochemistry SB RAS, Irkutsk, Russia3Novosibirsk State University, Novosibirsk, Russia4Max Planck Institute for Chemistry, Mainz, GermanyUltra-high-pressure diamondiferous rocks (UHP) of the Kokchetav subduction-collision zone are considered as an idealobject for studying the mobility of elements insubduction zones of the continental type. The compositional diversity of metasedimentary rocks subjected to UHP metamorphism makes it difficult to establish the nature of their protoliths. This, in turn, complicates estimatesof the degree of depletionof the UHP metamorphic rocks relative to the protoliths.To clarify the nature of protholiths of the Kokchetav diamondiferous rocks we studied the geochemical features and Sm-Nd isotopic composition of diamondiferous calc-silicate, garnet-pyroxene rocks, high-alumina metapelitesand barren granite-gneisses.The nine samples of the Kumdy Kol mocrodiamond deposit (one granite-gneiss, 4-calc-silicate rocks, 3-garnet-pyroxenite) yielded aSm-Nd whole-rockisochronageof 1052±44 Ma. This age is close to the age of formation of the granitic gneiss basement of the Kokchetav massif (1.2-1.05 Ga) (Glorie et al., 2015). Therefore, we assume that the protoliths of these rocks were basementrocks. In this interpretation, their geochemical features may not be directly related to the processes of ultrahigh-pressure metamorphism.At the same time, the high-alumina rocks of the Barchinsky area are depleted todifferent degreeswithrespect to LREE and K yieldeda whole-rockisochron with an age of 509 ± 32 Ma, which suggests partial melting of these rocks duringthe exhumation stage.It was previously assumed that metasedimentary rocks of the Kokchetav microcontinent are the protoliths of diamondiferous rocks (Buslov et al., 2015). However, this contradicts with Sm-Nd isotopic data for metasedimentary rocks of quartzite-schist sequences of the Kokchetav microcontinent (Kovach et al., 2017). The metasedimentary rocks of the Sharyk Formation are characterized by variations in the ?Nd(t)from +4.1 to -3.3 and intNd(DM)from 1.9 to 1.25 Ga, whereasin the UHP metamorphic rocks ?Nd(t)varies from -7.6 to -13.2, and the model ages range from 2.7 to 2.3 Ga. These data clearly indicate that the metasedimentary rocks of the Kokchetav massif could not be the protolith of the ultrahigh-pressure rocks.
DS200612-1270
2005
Jagoutz, F.Shatsky, V.S., Buzlukova, L.V., Jagoutz, F., Kozmenko, O.A., Mityukhin, S.I.Structure and evolution of the lower crust of the Daldyn Alakit district in the Yakutian diamond province ( from dat a on xenoliths).Russian Geology and Geophysics, Vol. 46, 12, pp. 1252-1270.Russia, YakutiaPetrology - peridotites
DS201112-0397
2011
Jagoutz, O.Gysi, A.P., Jagoutz, O., Schmidt, M.W., Targuisti, K.Petrogenesis of pyroxenites and melt infiltrations in the ultramafic complex of Beni Bousera, northern Morocco.Journal of Petrology, Vol. 52, 9, pp. 1679-1735.Africa, MoroccoMelting, delamination
DS201112-0398
2011
Jagoutz, O.Gysi, A.P., Jagoutz, O., Schmidt, M.W., Targuisti, K.Petrogenesis of pyroxenites and melt infiltrations in the ultramafic complex of Beni Bousera, northern Morocco.Journal of Petrology, Vol. 52, 9, pp. 1679-1735.Africa, MoroccoMetasomatism
DS201312-0433
2013
Jagoutz, O.Jagoutz, O., Schmidt, M.W.The composition of the foundered complement to the continental crust and re-evaluation of fluxes in arcs.Earth and Planetary Science Letters, Vol. 371-372, June pp. 177-190.MantleGeochronology
DS201412-0006
2014
Jagoutz, O.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
DS201412-0420
2014
Jagoutz, O.Jagoutz, O.Arc crustal differentiation mechanisms.Earth and Planetary Science Letters, Vol. 396, pp. 267-277.MantleGeodynamics
DS201507-0318
2015
Jagoutz, O.Jagoutz, O., Kelemen, P.B.Role of arc processes in the formation of continental crust.Annual Review of Earth and Planetary Sciences, Vol. 43, pp. 363-404.MantleMagmatism
DS201607-1304
2016
Jagoutz, O.Jagoutz, O., Kelemen, P.B.Role of arc progresses in the formation of continental crust.Annual Review of Earth and Planetary Sciences, Vol. 43, pp. 363-404.MantleMagmatism

Abstract: We review data and recent research on arc composition, focusing on the relatively complete arc crustal sections in the Jurassic Talkeetna arc (south central Alaska) and the Cretaceous Kohistan arc (northwest Pakistan), together with seismic data on the lower crust and uppermost mantle. Whereas primitive arc lavas are dominantly basaltic, the Kohistan crust is clearly andesitic and the Talkeetna crust could be andesitic. The andesitic compositions of the two arc sections are within the range of estimates for the major element composition of continental crust. Calculated seismic sections for Kohistan and Talkeetna provide a close match for the thicker parts of the active Izu arc, suggesting that it, too, could have an andesitic bulk composition. Because andesitic crust is buoyant with respect to the underlying mantle, much of this material represents a net addition to continental crust. Production of bulk crust from a parental melt in equilibrium with mantle olivine or pyroxene requires processing of igneous crust, probably via density instabilities. Delamination of dense cumulates from the base of arc crust, foundering into less dense, underlying mantle peridotite, is likely, as supported by geochemical evidence from Talkeetna and Kohistan. Relamination of buoyant, subducting material—during sediment subduction, subduction erosion, arcarc collision, and continental collision—is also likely.
DS201709-2017
2017
Jagoutz, O.Klein, B.Z., Jagoutz, O., Behn, M.D.Archean crustal compositions promote full mantle convection.Earth and Planetary Science Letters, Vol. 474, pp. 516-526.Mantlesubduction

Abstract: Higher mantle potential temperatures characterized the early Earth, resulting in thicker, more mafic oceanic crust entering subduction systems. This change in the composition of subducted slabs, combined with the enhanced temperature contrast between the slab and ambient mantle, would have altered the buoyancy forces driving subduction in the early Earth. Here we investigate this “compositional effect” through a combination of petrologic and thermal modeling. Specifically, we construct density profiles for sinking slabs under modern and early Earth conditions based on a range of mafic crust and mantle compositions. Slab and mantle densities are then determined from mineral assemblages calculated using the thermodynamic modeling program Perple_X along slab geotherms estimated from an analytic thermal model. Consistent with previous studies, we find that modern MORB compositions are typically less dense than the ambient mantle in the basalt barrier zone, located immediately beneath the mantle transition zone. By contrast, possible early Earth oceanic crust compositions are denser than ambient mantle at all depths down to 1000 km. This compositional effect results in slabs that would have more readily penetrated the transition zone, promoting single-layered convection and effective mantle mixing in the early Earth.
DS1992-0764
1992
Jagutz, E.Jacob, D.E., Jagutz, E.Diamondiferous eclogites and mixing of mantle componentsEos Transactions, Vol. 73, No. 14, April 7, supplement abstracts p. 324South AfricaGeochronology, Roberts Victor
DS202107-1095
2021
JAHCoward, S., Campbell, JAHAnalytics for effective investment in early stage diamond exploration. SAIMM Conference, 36 ppts. PdfGlobaleconomics
DS200512-0650
2004
Jah, B.Liu, X., Jah, B., Liu, D., Dong, S., Li, S.SHRIMP U-Pb zircon dating of a metagabbro and eclogites from western Dabie Shan ( Hong'an Block) Chin a and its tectonic implications.Tectonophysics, Vol. 394, 3-4, Dec. 1-, pp. 171-192.ChinaGeochronology, UHP
DS200812-0758
2008
Jahangiri, A.Moayyed, M., Moazzen, M., Calagari, A.A., Jahangiri, A., Modjarrad, M.Geochemistry and petrogenesis of lamprophyric dykes and the associated rocks from Eslamy Peninsula, NW Iran: implications for deep mantle metasomatism.Chemie der Erde, Vol. 68, 2, pp. 141-154.Europe, IranMetasomatism
DS2001-0175
2001
JahnChavagnac, V., Jahn, Villa, Whitehouse, LiuMultichronometric evidence for an in situ origin of the ultra high pressure metamorphic terrane of Dabie Shan.Journal of Geology, Vol. 109, pp. 633-46.Chinaultra high pressure (UHP), Qinling - Dabie orogenic belt
DS1996-0673
1996
Jahn, B.Jahn, B., Comichet, J., Yui, T.F.Ultrahigh epsilon neodymium eclogites from an ultrahigh pressure metamorphic terrane of China.Chemical Geology, Vol. 127, No. 1-3, Jan. 10, pp. 61-80.ChinaEclogites, Metamorphic rocks
DS2000-0959
2000
Jahn, B.Tsai, C-H., Lo C-H, Liou, J.G., Jahn, B.Evidence against subduction related magmatism for the Jiaoziyan gabbro northern Dabie Shan China.Geology, Vol. 28, No. 10, Oct. pp. 943-6.ChinaSubduction, Dabie Shan area
DS2003-0427
2003
Jahn, B.Fu, B., Touret, J.L., Zheng, Y.F., Jahn, B.Fluid inclusions in granulites, granulitized eclogites and garnet pyroxenites from theLithos, Vol. 70, 3-4, pp. 293-319.ChinaUHP, eclogites
DS2003-0641
2003
Jahn, B.Jahn, B., Fan, Q., Yang, J.J., Henin, O.Petrogenesis of the Maowu pyroxenite eclogite body from the UHP metamorphicLithos, Vol. 70, 3-4, pp. 243-67.ChinaUHP, geochronology
DS200412-0587
2003
Jahn, B.Fu, B., Touret, J.L., Zheng, Y.F., Jahn, B.Fluid inclusions in granulites, granulitized eclogites and garnet pyroxenites from the Dabie Sulu terranes, eastern China.Lithos, Vol. 70, 3-4, pp. 293-319.ChinaUHP, eclogites
DS200412-0898
2003
Jahn, B.Jahn, B., Fan, Q., Yang, J.J., Henin, O.Petrogenesis of the Maowu pyroxenite eclogite body from the UHP metamorphic terrane of Dabie Shan: chemical and isotopic constraLithos, Vol. 70, 3-4, pp. 243-67.ChinaUHP, geochronology
DS200512-0473
2005
Jahn, B.Jahn, B., Liu, X., Yui, T.F., Morin, N., Coz, M.B.High pressure/ultrahigh pressure eclogites from the Hongan Block, east central China: geochemical characterization, isotope disequilibrium, geochronologyContributions to Mineralogy and Petrology, Vol. 149, 5, pp. 499-526.Asia, ChinaUHP
DS1995-0865
1995
Jahn, B.M.Jahn, B.M.NCB-SCB: geochemical and isotopic constraints of coesite bearing eclogites from Sulu and Dabie MtnsTerra Nova, Abstract Vol., p. 339.ChinaCoesite, Eclogite
DS1998-0679
1998
Jahn, B.M.Jahn, B.M., Gruau, G., Rudnik, V.A.Archean crustal evolution of the Aldan Shield, Siberia: geochemical and isotopic constraints.Precambrian Research, Vol. 91, No. 3-4, Aug. pp. 333-364.Russia, Siberia, Aldan ShieldGeochronology, Geochemistry
DS1999-0332
1999
Jahn, B.M.Jahn, B.M., Wu, F., Tsai, C.H.Crust mantle interaction induced by deep subduction of the continentalcrust: geochemical and Sr neodymium isotopicChemical Geology, Vol. 157, No. 1-2, May 3, pp. 119-46.ChinaSubduction, ultramafic intrusions, Dabie Mountains
DS1999-0817
1999
Jahn, B.M.Yang, J.J., Jahn, B.M.Sinking intrusion model for the emplacement of garnet bearing peridotites into continent collision orogens...Geology, Vol. 27, No. 8, Aug. pp. 767-8.MantleSubduction, Petrology - peridotites
DS2000-0573
2000
Jahn, B.M.Liou, J.G., Zhang, R.Y., Jahn, B.M.Petrological and geochemical characteristics of ultrahigh pressure metamorphic rocks Dabie Sulu TerraneInternational Geology Review, Vol. 42, No. 4, Apr 1, pp. 328-52.China, East CentralPetrology, geochemistry, ultra high pressure (UHP), Deposit - Dabie Shan area
DS2000-1038
2000
Jahn, B.M.Yang, J.J., Jahn, B.M.Deep subduction of mantle derived garnet peridotites from Su Lu ultra high pressure metamorphic terrane in China.Igc 30th. Brasil, Aug. abstract only 1p.Chinaultra high pressure (UHP) metamorphism
DS200912-0439
2009
Jahn, B.M.Liou, J.G., Ernst, E.G., Zhang, R.Y., Tsujimori, T., Jahn, B.M.Ultrahigh pressure minerals and metamorphic terranes - the view from China.Journal of Asian Earth Sciences, Vol. 35, 3-4, pp. 199-231.ChinaUHP
DS201112-0173
2011
Jahn, B.M.Chauvel, C., Garcon, M., Arndt, N.T., Gallet, S., Jahn, B.M.Average Nd hf isotopic compositions and model age of the upper continental crust.Goldschmidt Conference 2011, abstract p.646.Africa, South AfricaBeach placers
DS1995-0866
1995
Jahn, B-M.Jahn, B-M., Condie, K.C.Evolution of the Kaapvaal Craton viewed from geochem.,samarium-neodymium (Sm-Nd) isotopic analyses intracratonic pelitesGeochimica et Cosmochimica Acta, Vol. 59, No. 11, pp. 2239-58South AfricaGeochronology, Kaapvaal Craton
DS1996-0262
1996
Jahn, B-m.Chavagnac, V., Jahn, B-m.Coesite bearing eclogites from the Bixiling Complex, Dabie Mountains, China: Sm neodymium ages, geochemical....Chemical Geology, Vol. 133, pp. 29-51.ChinaEclogites, coesites, Deposit -Dabie Mountains
DS2001-0525
2001
Jahn, B-M.Jahn, B-M., Caby, R., Monie, P.The oldest ultra high pressure (UHP) eclogites of the world: age of ultra high pressure (UHP) metamorphism, nature of protoliths and tectonic implic.Chemical Geology, Vol. 178, No. 1-4, pp. 143-58.GlobalEclogites, ultra high pressure (UHP), Geochronology
DS2002-0282
2002
Jahn, B-M.Chen, B., Jahn, B-M., Wei, C.Petrogenesis of Mesozoic granitoids in the Dabie UHP Complex, Central China: trace element and Nd Sr isotopeLithos, Vol. 60, No. 1-2, Jan. pp. 67-88.ChinaUltra high pressure, UHP, Geochronology
DS2003-1560
2003
Jahn, B-M.Zheng, Y-F., Yang, J-J., Gong, B., Jahn, B-M.Partial equilibrium of radiogenic and stable isotope systems in garnet peridotite duringAmerican Mineralogist, Vol. 88, pp. 1633-43.ChinaGeochronology, UHP
DS200412-2155
2004
Jahn, B-M.Xie, Z., Zheng, Y-F., Jahn, B-M., Ballevre, M., Chen, J., Gautier, P., Gao, T., Gong, B., Zhou, J.Sm Nd and Rb Sr dating of pyroxene garnetite from North Dabie in east centra China: problem of isotope disequilibrium due to retChemical Geology, Vol. 206, 1-2, May 28, pp. 137-158.ChinaUHP, eclogite, geochronology
DS200412-2227
2003
Jahn, B-M.Zheng, Y-F., Yang, J-J., Gong, B., Jahn, B-M.Partial equilibrium of radiogenic and stable isotope systems in garnet peridotite during ultrahigh pressure metamorphism.American Mineralogist, Vol. 88, pp. 1633-43.ChinaGeochronology, UHP, Shimafang, Sulu
DS200512-0474
2005
Jahn, B-M.Jahn, B-M., Liu, X., Yui, T-F., Morin, N., Bouhnik-Le Coz, M.High pressure ultrahigh pressure eclogites from the Hong an Block, east central China: geochemical characterization, isotope disequilibrium and geochronological controversy.Contributions to Mineralogy and Petrology, On lineChinaUHP
DS200512-0644
2005
Jahn, B-M.Lin,L.H., Wang, P-L., Lo, C-H., Tsai, C-H., Jahn, B-M.40 Ar 39 Ar thermochronological constraints on the exhumation of ultrahigh pressure metamorphic rocks in the Sulu Terrane of eastern China.International Geology Review, Vol. 47, 7, pp. 872-886.Asia, ChinaUHP
DS200512-1246
2004
Jahn, B-M.Zhang, R.Y., Liou, J.G., Yang, J.S., Liu, L., Jahn, B-M.Garnet peridotites in the UHP Mountain Belts of China.International Geology Review, Vol. 46, 11, pp. 981-1004.China, AsiaUHP
DS200612-1242
2006
Jahn, B-M.Schneider, J., Jahn, B-M., Okamoto, K., Tong, L., Lizuka, Y., Xu, Z.Rb Sr and Sm Nd isotope analyses of CCSD eclogites ( Sulu, China): a test for the closure temperature concept.Geochimica et Cosmochimica Acta, Vol. 70, 18, p. 12, abstract only.ChinaUHP, geochronology
DS200712-0479
2007
Jahn, B-m.Jahn, B-m., Chen, B.Dabie Shan UHP metamorphic terrane: Sr Nd Pb isotopic constraint to pre-metamorphic subduction polarity.International Geology Review, Vol. 49, 1, pp. 14-29.ChinaUHP
DS201012-0455
2010
Jahn, B-M.Liu, X., Jahn, B-M., Lou, Y.Diachronous subduction and exhumation of the Tongbai Dabie Sulu HP/UHP metamorphic belt in central China.Goldschmidt 2010 abstracts, posterChinaUHP
DS201112-1053
2011
Jahn, B-M.Tong, L., Jahn, B-M., Zheng, Y-F.Diverse P-T paths of the northern Dabie complex in central Chin a and its reworking in the early Cretaceous.Journal of Asian Earth Sciences, Vol. 42, 4, pp. 633-640.Asia, ChinaUHP
DS201312-0512
2013
Jahn, B-M.Kovach, V.,Salnikova, E., Wang, K-L., Jahn, B-M., Chiu, H-Y., Reznitskiy, L., Kotov, A., Lizuka, Y., Chung, S-L.Zircon ages and Hf isotopic constraints on sources of clastic metasediments of the Slyudyansky high grade complex, southeastern Siberia: implication for continental growth and evolution of the Central Asian orogenic belt.Journal of Asian Earth Sciences, Vol. 62, pp. 18-36.Russia, SiberiaUHP, Geochronology
DS200712-0480
2007
Jahn, S.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
Jahn, S.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
DS201212-0278
2012
Jahn, S.Haigis, V., Salanne, M., Jahn, S.Thermal conductivity of minerals in the Earth's lower mantle from molecular dynamics.emc2012 @ uni-frankfurt.de, 1p. AbstractMantleGeothermometry
DS201212-0279
2012
Jahn, S.Haigis, V., Salanne, M., Jahn, S.Thermal conductivity of MgO, MgSiO3 perovskite and post-perovskite in the Earth's deep mantle.Earth and Planetary Science Letters, Vol. 355-356, pp. 102-108.MantleGeothermometry
DS202105-0776
2021
Jahn, S.Martirosyan, N.S., Efthimiopoulos, I., Pennacchioni, L., Wirth, R., Jahn, S., Koch-Muller, M.Effect of catonic substitution on the pressure -induced phase transition in calcium carbonate.American Mineralogist, Vol. 106, pp. 549-558. pdfMantledeep carbon cycle
DS1995-0867
1995
Jahne, B.Jahne, B.Digital image processing.Springer, 396p. approx. $ 75.00GlobalBook -ad, Image processing
DS1940-0183
1948
Jahns, R.H.Jahns, R.H.The Gem Deposits of Southern CaliforniaEng. Sci. Monthly; Gems And Gemology, Vol. 11, No. 2, PP. 6-9; Vol. 6, PP. 6-9, 28, 30.United States, California, West CoastBlank
DS1960-0058
1960
Jahns, R.H.Jahns, R.H.Gem Stones and Allied MineralsIn: Industrial Minerals And Rocks, American Institute of Mining, Metallurgical, And Petroleum Engineers (aime), PP. 383-441.South Africa, Southwest Africa, GlobalDiamonds, Production, Figures
DS1960-0059
1960
Jahns, R.H.Jahns, R.H.Precious Stones (1960)Industrial Minerals And Rocks, American Institute of Mining, PP. 383-441.United States, CanadaBlank
DS2002-0759
2002
Jahren, A.H.Jahren, A.H.The biogeochemical consequences of the mid-Cretaceous superplumeJournal of Geodynamics, Vol.34,2, Sept. pp. 163-76.GlobalBiogeochemistry, Mantle plumes, hot spots
DS1996-0674
1996
Jaillard, E.Jaillard, E., Soler, P.Cretaceous to early Paleocene tectonic evolution of the northern Central Andes 0-10 and its relations geodynaM.Tectonophysics, Vol. 259, No. 1-3, June 30, pp. 41-54Andes, Cordillera, Bolivia, ArgentinaGeodynamics, Tectonics
DS2002-0760
2002
Jaillard, E.Jaillard, E., Herail, G., Monfret, T., Worner, G.Andean geodynamics: main issues and contributions from the 4th. ISAGTectonophysics, Vol.345, 1-4, Feb.15, pp. 1-15.AndesGeodynamics - brief review
DS2001-0424
2001
Jaillard, Yepes et al.Guililer, B., Chatelain, J.L., Jaillard, Yepes et al.Seismological evidence on the geometry of the orogenic system in central northern Ecuador.Geophysical Research Letters, Vol. 28, No. 19, Oct. 1, pp. 3749-52.Ecuador, South AmericaGeophysics - seismics, Tectonics
DS1999-0018
1999
Jaillard. E.Arculus, R.J., Lapierre, H., Jaillard. E.Geochemical window into subduction and accretion processes: Raspas metamorphic complex, Ecuador.Geology, Vol. 27, No. 6, June, pp. 547-50.EcuadorLithosphere, subduction, Geochemistry - Raspas
DS1988-0324
1988
JainJain, Ajai Kumar, Tapi, R.D.Study of carbonatite in the northeast of BarwahDistrict, Khargone, SOURCE[ Vijana Parshad Anusandhan Patrike, (Ind)Vijana Parshad Anusandhan Patrike, (Ind), Vol. 31, No. 2-3, June pp. 89-96IndiaCarbonatite
DS1995-0385
1995
Jain, A.K.Das, J.D. , saraf, A.K., Jain, A.K.Fault tectonics of the Shilong plateau and adjoining regions, north-east India using remote sensing dataInternational Journal of Remote Sensing, Vol. 16, No. 9, June pp. 1633-46IndiaRemote Sensing, Tectonics
DS202005-0730
2020
Jain, A.K.Fareeduddin., Pant, N.C., Gupta, S., Chakraborty, P., Sensarma, S., Jain, A.K., Prasad, G.V.R., Srivastava, P., Rjan, S., Tiwari, V.M.The geodynamic evolution of the Indian subcontinent - an introduction.Episodes ( IUGS), Vol. 43, 1, pp. 1-18.Indiacarbonatite
DS202009-1627
2020
Jain, A.K.Fareeduddin, Pant, N.C., Gupta, S., Chakraborty, P., Sensarma, S., Jain, A.K., Prasad, G.V.R., Srivastava, P., Rajan, S., Tiwari, V.M.The geodynamic evolution of the Indian subcontinent - an introduction.Episodes, Vol. 43, 1, pp. 8p.Indiacarbonatites
DS1982-0295
1982
Jain, B.K.Jain, B.K., Regan, R.D.Integration of Satellite and Conventional Geophysical Dat a with tectonics and Structural Information Over the African Continent.Geoexploration., Vol. 20, No. 3-4, PP. 233-258.Africa, West Africa, Central Africa, East Africa, Southwest AfricaStructure, Tectonics, Remote Sensing
DS201706-1102
2017
Jain, C.Rozel, A.B., Golabek, G.J., Jain, C., Tackley, P.J., Gerya, T.Continental crust formation on early Earth controlled by intrusive magmatism.Nature, online availableMantlegeodynamics

Abstract: The global geodynamic regime of early Earth, which operated before the onset of plate tectonics, remains contentious. As geological and geochemical data suggest hotter Archean mantle temperature1, 2 and more intense juvenile magmatism than in the present-day Earth3, 4, two crust-mantle interaction modes differing in melt eruption efficiency have been proposed: the Io-like heat-pipe tectonics regime dominated by volcanism5, 6 and the “Plutonic squishy lid” tectonics regime governed by intrusive magmatism, which is thought to apply to the dynamics of Venus7, 8, 9. Both tectonics regimes are capable of producing primordial tonalite-trondhjemite-granodiorite (TTG) continental crust5, 10 but lithospheric geotherms and crust production rates as well as proportions of various TTG compositions differ greatly9, 10, which implies that the heat-pipe and Plutonic squishy lid hypotheses can be tested using natural data11. Here we investigate the creation of primordial TTG-like continental crust using self-consistent numerical models of global thermochemical convection associated with magmatic processes. We show that the volcanism-dominated heat-pipe tectonics model results in cold crustal geotherms and is not able to produce Earth-like primordial continental crust. In contrast, the Plutonic squishy lid tectonics regime dominated by intrusive magmatism results in hotter crustal geotherms and is capable of reproducing the observed proportions of various TTG rocks. Using a systematic parameter study, we show that the typical modern eruption efficiency of less than 40 per cent12 leads to the production of the expected amounts of the three main primordial crustal compositions previously reported from field data4, 11 (low-, medium- and high-pressure TTG). Our study thus suggests that the pre-plate-tectonics Archean Earth operated globally in the Plutonic squishy lid regime rather than in an Io-like heat-pipe regime.
DS201905-1047
2019
Jain, C.Jain, C., Rozel, A.B., Tackley, P.J.Quantifying the correlation between mobile continents and elevated temperatures in the subcontinental mantle.Geochemistry, Geophysics, Geosystems, Vol. 20, 3, pp. 1358-1386.Mantlegeothermometry

Abstract: Continents influence the mantle's convective wavelength and the heat flow escaping from the planet's surface. Over the last few decades, many numerical and analytical studies have contributed to the debate about whether the continents can warm up the subcontinental mantle or not and if they do, then to what extent? However, a consensus regarding the exact nature and magnitude of this correlation between continents and elevated temperatures in the subcontinental mantle remains to be achieved. By conducting a systematic parameter study using 2-D global mantle convection simulations with mobile continents, we provide qualitative and quantitative observations on the nature of this correlation. In our incompressible and compressible convection models, we observe the general processes of downwellings bringing cold material into the mantle along continental margins and a subsequent buildup of warm thermal anomalies underneath the continents. We compute the amplitude and degree of this correlation using spectral decomposition of the temperature and composition fields. The dominant degree of correlation evolves with time and changes with continental configuration. Using simple empirical fits, we observe that this correlation decreases with increasing core temperature, number of continents, internal heating, or decreasing reference viscosity. We also report simple regressions of the time dependence of this correlation. Additionally, we show that decompression melting as a result of a mantle upwelling or small-scale sublithospheric convection leads to voluminous volcanism. The emplacement of this dense basalt-eclogite material breaks the continents apart and destroys the correlation.
DS201908-1780
2019
Jain, C.Jain, C., Rozel, A.B., Tackley, P.J., Sanan, P., Gerya, T.V.Growing primordial continental crust self-consistently in global mantle convection models.Gondwana Research, Vol. 73, pp. 96-122.Mantlegeothermometry

Abstract: The majority of continental crust formed during the hotter Archean was composed of Tonalite-Trondhjemite-Granodiorite (TTG) rocks. In contrast to the present-day loci of crust formation around subduction zones and intra-plate tectonic settings, TTGs are formed when hydrated basalt melts at garnet-amphibolite, granulite or eclogite facies conditions. Generating continental crust requires a two step differentiation process. Basaltic magma is extracted from the pyrolytic mantle, is hydrated, and then partially melts to form continental crust. Here, we parameterise the melt production and melt extraction processes and show self-consistent generation of primordial continental crust using evolutionary thermochemical mantle convection models. To study the growth of TTG and the geodynamic regime of early Earth, we systematically vary the ratio of intrusive (plutonic) and eruptive (volcanic) magmatism, initial core temperature, and internal friction coefficient. As the amount of TTG that can be extracted from the basalt (or basalt-to-TTG production efficiency) is not known, we also test two different values in our simulations, thereby limiting TTG mass to 10% or 50% of basalt mass. For simulations with lower basalt-to-TTG production efficiency, the volume of TTG crust produced is in agreement with net crustal growth models but overall crustal (basaltic and TTG) composition stays more mafic than expected from geochemical data. With higher production efficiency, abundant TTG crust is produced, with a production rate far exceeding typical net crustal growth models but the felsic to mafic crustal ratio follows the expected trend. These modelling results indicate that (i) early Earth exhibited a "plutonic squishy lid" or vertical-tectonics geodynamic regime, (ii) present-day slab-driven subduction was not necessary for the production of early continental crust, and (iii) the Archean Earth was dominated by intrusive magmatism as opposed to "heat-pipe" eruptive magmatism.
DS1995-0526
1995
Jain, J.C.Fedorowich, J.S., Jain, J.C., Kerrich, R., Sopuck, V.Trace element analysis of garnet by laser-ablation microprobe ICP-MS....pyrope garnet.Canadian Mineralogist, Vol. 33, No. 2, April pp. 469-480.Wyoming, South AfricaGarnet -mass spectrometry, Deposit -Schaffer, Frank Smith
DS200912-0332
2009
Jain, P.K.Jain, P.K.Mineral royalty in India and its comparison with selected countries.Minerals & Energy - Raw Materials Report, Vol. 23, 3, pp. 119-126.IndiaLegal
DS1975-0585
1977
Jain, R.S.Nautiyal, S.P., Jain, R.S.On the Prospect of Locating New Diamondiferous Areas in IndiIndia Geological Survey Records, Vol. 108, PT. 2, PP. 157-166.IndiaDiamond Occurrences, Prospecting
DS1991-0784
1991
Jaireth, S.Jaireth, S., Sen, A.K., Varma, O.P.Fluid inclusion studies in apatite of the Sung Valley carbonatite northeast India: evidence of melt-fluid immiscibilityJournal of Geological Society India, Vol. 37, June pp. 547-559IndiaCarbonatite, Geochemistry
DS201412-0422
2014
Jaireth, S.Jaireth, S., Hoatson, D.M., Miezitis, Y.Geological setting and resources of the major rare-earth-element deposits in Australia.Ore Geology Reviews, Vol. 61, pp. 72-128.AustraliaREE in alkaline rocks
DS1998-1454
1998
Jakimowicz, J.Taylor, W.R., Reddicliffe, T.H., Jakimowicz, J.Thermobarometry of peridotitic chromium diopside from the Merlin kimberlites -nature of upper mantle..7th International Kimberlite Conference Abstract, pp. 899-901.AustraliaProterozoic, craton, Deposit - Merlin
DS2003-1146
2003
Jakimowicz, J.Reddicliffe, T.H., Jakimowicz, J., Hell, A.J., Robins, J.A.The geology, mineralogy and near surface chacteristics of the Ashmore and Seppelt8ikc, Www.venuewest.com/8ikc/program.htm, Session 1 POSTER abstractAustraliaKimberlite geology and economics, Deposit - Ashmore, Seppelt
DS200912-0489
2009
Jakimowicz, J.McInnes, B.I.A., Evans, N.J., McDonald, B.J., Kinny, P.D., Jakimowicz, J.Zircon U Th Pb He double dating of the Merlin kimberlite field, Northern Territory, Australia.Lithos, In press availableAustraliaDeposit - Merlin
DS201412-0940
2014
Jakins, A.Van der Westhuyzen, P., Bouwer, W., Jakins, A.Current trends in the development of new or optimization of existing diamond processing plants, with focus on beneficiation.South African Institute of Mining and Metallurgy, Vol. 114, July pp. 537-546.TechnologyDiamond processing plants
DS202007-1158
2020
Jakkawanvibul, J.Leelawatanasuk, T., Atichat, W., Pisutha-Arnond, V., Sutthirat, C., Jakkawanvibul, J., GITTwo decades of GIT's ruby and sapphire color standards.incolorMagazine.com, Vol. winter pp. 96-103.Asia, Thailandsapphire colour
DS1996-0675
1996
Jakni, B.Jakni, B., Dautria, J-M., Liotard, J-M., Brigueu, L.Evidence of the presence of a carbonated mantle beneath Bas-Languedoc:peridotitic xenoliths Grand Magnon...C.r. Academy Of Science Paris., *french, Vol. 323, iia, pp. 33-40.FranceXenoliths, Basanites, Leucito-nephelinites
DS1975-1045
1979
Jakob, W.K.O.Gurney, J.J., Jakob, W.K.O., Dawson, J.B.Metacrysts from the Monastery Kimberlite PipeProceedings of Second International Kimberlite Conference, Proceedings Vol. 2, PP. 227-243.South AfricaPetrography
DS1975-0539
1977
Jakob, W.R.O.Jakob, W.R.O.Geochemical Aspects of the Megacryst Suite from the Monastery Kimberlite Pipe.Cape Town: Msc. Thesis, University Cape Town., 81P.South AfricaGeochemistry
DS1996-1132
1996
Jakobsen, R.Postma, D., Jakobsen, R.Redox zonation: equilibrium constraints on the iron (III) SO4 reductioninterface.Geochimica et Cosmochimica Acta, Vol. 60, No. 17, pp. 3169-75.GlobalGeochemistry - redox not specific to diamonds
DS200812-0514
2008
Jakobsson, S.Jakobsson, S., Holloway, J.R.Mantle melting in equilibrium with an iron wustite.. graphite buffered COH fluid.Contributions to Mineralogy and Petrology, Vol. 155, 2, pp. 247-256.MantleMelting
DS1994-0922
1994
Jakop, Z.J.Kjarsgaard, B.A., Spark, R.N., Jakop, Z.J.Preliminary geology Kaola 76D/10Geological Survey of Canada (GSC) Open File, No. 2966, map, 1: 50, 000Northwest TerritoriesGeology
DS1994-0923
1994
Jakop, Z.J.Kjarsgaard, B.A., Spark, R.N., Jakop, Z.J.Geology, Ursula Lake 76D/16Geological Survey of Canada (GSC) Open File, No. 2967, map, 1: 50, 000Northwest TerritoriesGeology
DS1994-0924
1994
Jakop, Z.J.Kjarsgaard, B.A., Spark, R.N., Jakop, Z.J.Preliminary geology Koala District of MackenzieGeological Survey of Canada Open file Map., No. 2966, 1: 50, 000 $ 19.75Northwest TerritoriesGeology map, Koala area
DS1994-0925
1994
Jakop, Z.J.Kjarsgaard, B.A., Spark, R.N., Jakop, Z.J.Preliminary geology Ursula Lake District of MackenzieGeological Survey of Canada Open file Map., No. 2967, 1: 50, 000 $ 19.75Northwest TerritoriesGeology map, Ursula Lake area
DS1995-0868
1995
Jakop, Z.J.Jakop, Z.J.Petrology and heavy mineral concentrate analysis of kimberlites, GuigueTownship, determination-economicCarleton University, BSc. Thesis, 75p.QuebecPetrology, Deposit -Guigue
DS1999-0364
1999
Jakop, Z.J.Kjarsgaard, B.A., Jakop, Z.J., Spark, R.N.Preliminary geology, Exeter Lake 76D/15Geological Survey of Canada (GSC) Open File, No. 3702, map, 1: 50, 000Northwest TerritoriesGeology
DS200512-0541
2005
Jakop, Z.J.Kjarsgaard, B.A., Spark, R.N., Jakop, Z.J.Preliminary geology Koala district of Mackenzie Northwest Territories. Map 76 D 10.Geological Survey of Canada Open File, OF 2966 $ 21.00Canada, Northwest TerritoriesGeology map
DS200512-0542
2005
Jakop, Z.J.Kjarsgaard, B.A., Spark, R.N., Jakop, Z.J.Preliminary geology Ursula Lake district of Mackenzie Northwest Territories. Map 76 D 16.Geological Survey of Canada Open File, OF 2967 $ 21.00Canada, Northwest TerritoriesGeology map
DS201212-0336
2012
Jakovlev, A.V.Jakovlev, A.V., Bushenkova, N.A., Koulakov, I.yu., Dobretsov, N.L.Structure of the upper mantle in the circum-artic region from regional seismic tomography.Russian Geology and Geophysics, Vol. 53, 10. pp. 963-971.RussiaGeophysics - seismic
DS200412-0899
2004
Jakubec, C.Jakubec, C.From exploration geology to mine design.PDAC 2004, 1p. abtract.GlobalMine risk
DS1995-0869
1995
Jakubec, J.Jakubec, J., Milton, A., Siwawa, C.Z., Struik, M.J.P.M.Improvement in blasting techniques at Orapa and Letlhakane diamond Mines -a holistic approach.African Mining 95, Institute of Mining and Metallurgy (IMM) Publishing, pp. 285-304.BotswanaMining, Deposit -Orapa and Letlhakane
DS2003-0642
2003
Jakubec, J.Jakubec, J.Role of geology in project development8 Ikc Www.venuewest.com/8ikc/program.htm, Session 1, AbstractNorthwest TerritoriesPipe emplacement, Deposit - Ekati
DS2003-0643
2003
Jakubec, J.Jakubec, J., Long, L.Underground geotechnical and geological investigation at Ekati diamond mine - Koala8ikc, Www.venuewest.com/8ikc/program.htm, Session 1 POSTER abstractNorthwest TerritoriesKimberlite geology and economics, Deposit - Koalo North
DS200412-0900
2003
Jakubec, J.Jakubec, J.Role of geology in project development.8 IKC Program, Session 1, AbstractCanada, Northwest TerritoriesPipe emplacement Deposit - Ekati
DS200612-0634
2006
Jakubec, J.Jakubec, J.Diamond project management - a holistic approach.CIM Conference and Exhibition, Vancouver - Creating Value with Values, List of talks CIM Magazine, Feb. p. 77.GlobalMining
DS200612-0635
2006
Jakubec, J.Jakubec, J.Kimberlite emplacement model - impact on diamond project development.Emplacement Workshop held September, 5p. extended abstractGlobalMining issues, pipe geometry, Country rock, dilution
DS200812-0515
2008
Jakubec, J.Jakubec, J.Kimberlite emplacement models - the implications for mining projects.Journal of Volcanology and Geothermal Research, Vol. 174, 1-3, pp. 20-28.GlobalEmplacement models, diamond mining
DS201503-0151
2015
Jakubec, J.Jakubec, J., Johnson, M.The Jericho diamond mine - what happened?Vancouver Kimberlite Cluster, Feb. 20, 1p. AbstractCanada, NunavutDeposit - Jericho
DS201708-1678
2017
Jakubec, J.Jakubec, J.Mining for diamonds - history and present.11th. International Kimberlite Conference, OralGlobalBlank
DS201708-1679
2017
Jakubec, J.Jakubec, J.Underground diamond mining at Ekati and Diavik mines.11th. International Kimberlite Conference, PosterCanada, Northwest Territoriesdeposit - Ekati, Diavik
DS201709-2020
2017
JakubovaKotova, J., Fedortchouk, Y., Wirth, R., Whitehouse, M., JakubovaUHP-UHT melting and diamond formation. MicrodiamondsGoldschmidt Conference, abstract 1p.MantleUHP

Abstract: Exhumed ultrahigh-pressure (UHP) terranes, involving slices of deeply subducted crustal rocks, provide unique material for studying material transfer in subduction zones. Diamond-bearing UHP rocks with sedimentary protoliths allow for tracing melting processes at both UHP and UHT including carbon cycling in the Earth. We studied microdiamonds and associated phases in two contrasting lithologies, (1) acid, quartzofeldpathic UHP gneiss composed of garnet, kyanite, feldspar, quartz and biotite, with a high ASI characteristic of sedimentary rocks, and (2) intermediate garnet-clinopyroxene rock containing quartz, feldspar, minor kyanite and biotite, which is metaluminous. Whereas rock (1) contains exclusively single octahedral diamonds with perfect crystal shape in garnet, kyanite (more common) and zircon, the microdiamonds in the rock (2) occur mostly as clusters of cuboid shape in garnet and zircon. Micro-Raman and FIB TEM data document presence of graphite, quartz and rutile at diamond/host interface or in separate multiple solid inclusions (MSI) whereas carbonates are practically absent. The morphology and lack of inclusions reflect relatively slow growth of the octahedral diamonds (rock 1) at lower fluid supersaturation. Individual deep and symmetrical negative trigons (AFM) on the (111) plane suggest dissolution by a residual silicate-carbonate melt. In contrast, polycrystallline character of diamond cuboids (rock 2) along with their common dissolution and formation of numerous tetragonal etch pits reflect relatively rapid growth of these grains from highly supersaturated fluid/melt. Peak P-T conditions for the UHP rocks of = 1100ºC at 4.5 GPa are located above the phengite dehydration melting curve, where silicate melts are produced and may coexist with carbonate melts. In view of the light carbon isotope composition and lack of carbonates, we suggest that the diamonds crystallized from the graphitized primordial organic matter under reducing conditions at presence of silicate melt.
DS201612-2312
2016
Jakubova, P.Kotkova, J., Fedortchouk, Y., Jakubova, P., Whitehouse, M., Wirth, R.Bohemian microdiamonds: diamond forming media and carbon source.Acta Geologica Sinica, Vol. 90, 1, July abstract P. 217-219.EuropeMicrodiamonds
DS201112-0474
2011
Jakusconek, T.Jakusconek, T.Rough times behind - sparkle ahead. Harry Winston featured and recommended.Scotia Capital Equity Research Report, June 29, 38p.Canada, Northwest Territories, GlobalNews item - Harry Winston
DS201312-0434
2013
Jakusconek, T.Jakusconek, T., et al.Diamond Quarterly Review: The carat chronicles Q1/13.Scotia Capital Equity Research Report, 36p.GlobalReview of companies
DS1989-0697
1989
Jalahi, S.Jalahi, S.Diamond - with a color change garnet inclusionGems and Gemology - Gem Trade Lab Notes, Vol. 25, No. 4, Winter pp. 237-238GlobalDiamond morphology, Diamond inclusion
DS201903-0548
2019
Jalowitski, T.Vieira Conceicao, R., Colombo Carniel, L., Jalowitski, T., Gervasoni, F., Grings Cedeno, D.Geochemistry and geodynamic implications on the source of Parana-Etendeka Large Igneous Province evidenced by the late 128 Ma Rosario-6 kimberlite, southern Brazil.Lithos, Vol. 328-329, pp. 130-145.South America, Brazildeposit - Rosario-6

Abstract: The Rosário-6 is a non-diamondiferous hypabyssal kimberlite located above the Rio de la Plata craton and near the south-eastern edge of the Paraná Basin, in southern Brazil. It is petrographically an inequigranular texture, macrocrystal kimberlite, fresh and the groundmass exhibits a microporphyritic texture and round megacrysts of olivine, which are derived from disaggregated mantle xenoliths. Olivine is also present as macrocrysts, microphenocrysts and in the groundmass together with phlogopite and apatite. These microphenocrysts are immersed in a groundmass of olivine, monticellite, phlogopite, CaTiO3-perovskite, apatite, Mg-chromite and Mg-ulvöspinel and melilite. A mesostasis assemblage of phlogopite, melilite, soda melilite, akermanite and calcium carbonate is segregated from the groundmass. Its geochemical signature is similar to those of transitional kimberlites of Kaapvaal Craton, South Africa, and the U-Pb ages of ~ 128 Ma on perovskite reveal that Rosário-6 kimberlite post-dates the main pulse of volcanism in the Paraná-Etendeka Large Igneous Province (LIP). The high Ti content of some minerals, such as Mg-chromite, Mg-ulvöspinel, phlogopite and melilite, and the presence of perovskite suggest a Ti-rich source. The petrographic, geochemical and isotopic data indicate that the Rosário-6 kimberlite source is a depleted mantle metasomatized by H2O-rich fluids, CO2-rich and silicate melts derived from the recycling of an ancient subducted oceanic plate (eclogite) before the South Atlantic opening. Although several authors indicate the influence of Tristan da Cunha plume for the generation of alkaline magmatism associated to the Paraná-Etendeka flood basalts, our data demonstrates that Tristan da Cunha plume has no chemical contribution to the generation of Rosário-6 kimberlite, except by its thermal influence.
DS202008-1402
2020
Jalowitzki, T.Jalowitzki, T., Gervasoni, F., Sumino, H., Klemme, S., Berndt, J., Dalla Costa, M., Fuck, R.A.Plume subduction events recorded by KS2 kimberlite indicator minerals from Juina, Brazil.Goldschmidt 2020, 1p. AbstractSouth America, Brazil, Mato Grossodeposit - Juina

Abstract: The Cretaceous Juína Kimberlite Province (JKP, 95-92 Ma) is located in the southwest of the Amazonian Craton, northwest of Mato Grosso, Brazil. Here we present new geochemical and isotopic data of garnet (n=187) and zircon (n=25) megacrysts collected from the KS2 kimberlite. The magmatic zircon megacrysts have U-Pb ages of 92.1 ± 0.7 Ma. The chondrite-normalized rare earth element (REE) patterns (LREE
DS202101-0002
2020
Jalowitzki, T.Carniel, L.C., Conceicao, R.V., Klemme, S., Berndt,J., Jalowitzki, T.Origin and redox conditions of the Rosario-6 alnoite of southern Brazil: implications for the state of the mantle during Gondwana breakup.Lithos, Vol. 376-377, 105751, 13p. PdfSouth America, Brazildeposit - Rosario do Sul

Abstract: The Rosário-6 alnöite is an alkaline occurrence that belongs to the Rosário do Sul kimberlitic field, situated in the south-eastern edge of the Paraná Basin, in the South of Brazil, and erupted concomitant or just after the volcanism of the Paraná-Etendeka Large Igneous Province (LIP). Following recent published nomenclature, Rosário-6 was classified as a kimberlite from a deep mantle source with a distinctive inequigranular texture resulting from the presence of olivine macrocrysts set in a finer-grained matrix. Trace element compositions of olivine, monticellite, spinel, phlogopite, perovskite and apatite show an enrichment of Nb, Ce, Ta and U, which implies that the Rosário-6 mantle source was enriched by recycled oceanic crust. The positive anomalies of Rb, Ba and Sr, the enrichment in LREE, and the negative anomalies of HREE in the Rosário-6 minerals, are indicative of a metasomatic process in the mantle source that could be caused by fluids from recycled oceanic crust. Temperature, pressure and redox conditions (fO2) of Rosário-6 crystallization are estimated from olivine, spinel, perovskite and monticellite compositions: Rosário-6 crystallization temperatures using olivine-spinel geothermobarometry were around 1390(±56)°C at a pressure of 2 GPa, and 1405(±56)°C at 3 GPa with ?NNO = 2.8, at pressures constrained by the silica activity limited by the crystallization of monticellite. Using a perovskite oxybarometer, we obtained a larger range of ?NNO (from -2.8 to 3.4), whereas the monticellite oxybarometer results in fO2 of -2.6 to -0.8 ?NNO units. The fO2 indicate that the mantle source of Rosário-6 at the time of crystallization was possibly oxidized by materials from ancient subduction, which may be the cause for Rosário-6's low potential to carry and preserve diamonds. Horizontal tomographic images derived from P-wave velocity data constrain the thickness of the lithosphere in this region and the overall information indicates that mantle cooling at depths below 200 km may have resulted of an accumulation of oceanic plate slabs from old subduction. The geochemical data in conjunction with the geophysical characterizes the conditions of Rosário-6 mineral crystallization and also the mantle of this part of South America during Gondwana breakup.
DS202109-1458
2021
Jalowitzki, T.de Caravlho, L.D.V., Jalowitzki, T., Scholz, R., de Oliveira Gonzales, G., Rocha, M.P., Peeira, R.S., Lana, C., de Castro, P., Queiroga, G., Fuck, R.A.An exotic Cretaceous kimberlite linked to metasomatized lithospheric mantle beneath the southwestern margin of the Sao Francisco Craton, Brazil.Geoscience Frontiers, doi,org/101016/j.gsf.2021.101.28South America, Brazildeposit - Osvaldo Franca 1

Abstract: We present major and trace element compositions of mineral concentrates comprising garnet xenocrysts, ilmenite, phlogopite, spinel, zircon, and uncommon minerals (titanite, calzirtite, anatase, baddeleyite and pyrochlore) of a newly discovered Late Cretaceous kimberlite (U-Pb zircon age 90.0 ± 1.3 Ma; 2s) named Osvaldo França 1, located in the Alto Paranaíba Igneous Province (APIP), southeastern Brazil. Pyrope grains are lherzolitic (Lherz-1, Lherz-2 and Lherz-3), harzburgitic (Harz-3) and wehrlitic (Wehr-2). The pyrope xenocrysts cover a wide mantle column in the subcratonic lithosphere (66-143 km; 20-43 kbar) at relatively low temperatures (811-875 °C). The shallowest part of this mantle is represented by Lherz-1 pyropes (20-32 kbar), which have low-Cr (Cr2O3 = 1.74-6.89 wt.%) and fractionated middle to heavy rare earth elements (MREE-HREE) pattern. The deepest samples are represented by Lherz-2, Lherz-3, Harz-3, and Wehr-2 pyropes (36-43 kbar). They contain high-Cr contents (Cr2O3 = 7.36-11.19 wt.%) and are characterized by sinusoidal (Lherz-2 and Wehr-2) and spoon-like (Lherz-3 and Harz-3) REE patterns. According to their REE and trace elements, pyrope xenocrysts have enriched nature (e.g., Ce and Yb vs. Cr2O3), indicating that the cratonic lithosphere has been affected by a silicate melt with subalkaline/tholeiite composition due to their low Zr, Ti and Y concentrations. Besides minerals with typical kimberlitic signatures, such as ilmenite and zircon, the exotic compositions of phlogopite and ulvöspinel suggest an enriched component in the magma source. The formation of rare mineral phases with strong enrichment of light-REE (LREE) and high field strength elements (HFSE) is attributed to the late-stage kimberlitic melt. We propose a tectonic model where a thermal anomaly, represented by the low-velocity seismic anomaly observed in P-wave seismic tomography images, supplied heat to activate the alkaline magmatism from a metasomatized cratonic mantle source during the late-stages of Gondwana fragmentation and consequent South Atlantic Ocean opening. The metasomatism recorded by mineral phases is a product of long-lived recycling of subducted oceanic plates since the Neoproterozoic (Brasiliano Orogeny) or even older collisional events, contributing to the exotic character of the Osvaldo França 1 kimberlite, as well as to the cratonic lithospheric mantle.
DS201705-0821
2017
Jamal, D.L.Chauque, F.R., Cordani, U.G., Jamal, D.L., Onoe, A.T.The Zimbabwe Craton in Mozambique: a brief review of its geochronological pattern and its relation to the Mozambique Belt.Journal of African Earth Sciences, Vol. 129, pp. 366-379.Africa, MozambiqueCraton, Zimbabwe

Abstract: The eastern margin of the Zimbabwe Craton, along the Mozambique-Zimbabwe border, includes the oldest rocks of west-central Mozambique constituting a large terrain of granite-greenstone type dated between 3000 and 2500 Ma. These rocks consist mainly of gneisses and granitoid rocks of tonalitic-trondhjemitic-granodioritic composition belonging to the Mudzi Metamorphic Complex in the northern part and to the Mavonde Complex in the southern part. The latter is associated with a granite-greenstone terrain, which includes the eastern part of Mutare-Odzi-Manica greenstone belt. A volcano-sedimentary sequences cover, belonging to the apparently Mesoproterozoic and Paleoproterozoic Umkondo and Gairezi groups respectively was deposited along the eastern margin of the craton and is exposed in the territory of Mozambique. The Umkondo minimum age is marked by intrusive dolerite in Zimbabwe dated at 1100 Ma while for the Ghairezi it is still not well established. The Gairezi Group was subjected to progressive metamorphism of Pan-African age. At the margin of the Zimbabwe Craton, in its northern part, metasedimentary units occur representing a passive margin of Neoproterozoic age. They make up the Rushinga Group, which includes felsic metavolcanic rocks dated at ca.800 Ma. Granulites and medium- to high-grade paragneisses, and migmatites of the Chimoio, Macossa and Mungari Groups of Neoproterozoic metamorphic age, overly the ortho-metamorphic pre-existing rock of ca. 1100 Ma, which belongs to the Báruè Magmatic Arc. They characterize the N-S trend Mozambique Belt, which appears to the east of the craton tectonically juxtaposed on the Archean rocks. The maximum age of deposition of these rocks, indicated by U-Pb dating of detrital zircons, is ca. 700 Ma and their minimum age is limited by a few monzonitic Cambrian intrusions dated at ca. 500 Ma. The Neoproterozoic bimodal Guro Suite, dated at ca. 850 Ma and composed of felsic and mafic members characterizes the east-dipping outer rim of the craton margin in the north. The felsic member comprises the Serra Banguatere aplitic granite gneiss-migmatite and the mafic member consists of the Magasso metagabbro and mafic gneiss-migmatite. The geochemical signature and bimodality are all characteristics of anorogenic, A-type granites. The tectono-thermal effects of the Pan-African orogenic event, of approximately 500 Ma, are visible along the margin of the Zimbabwe Craton. Deformation and metamorphism are progressive from the craton towards the belt, from greenschist facies to granulite facies. The main suture in the study area shall be placed along the frontal thrusts of the Mungari and Macossa/Chimoio nappes of Neoproterozoic to Cambrian age. To the west of the suture the rejuvenated margin of the craton occurs, indicated by K-Ar dating. To the east, the Mozambique Belt occurs with its paragneisses of the Neoproterozoic overlaying the Mesoproterozoic granitoids of the Báruè magmatic arc.
DS201909-2099
2019
Jamal, D.L.Turunen, S.T., Luttinen, A.V., Heinonen, J.S., Jamal, D.L.Luenha picrites, central Mozambique - messengers from a mantle plume source of Karoo continental flood basalts?Lithos, Vol. 346-347, 16p. PdfAfrica, Mozambiquepicrites

Abstract: We present geochemical and isotopic (Nd, Sr) data for a picrite lava suite from the Luenha River and adjacent areas in Mozambique. The Luenha picrites represent a previously unknown type of picrites related to the Karoo large igneous province (LIP) and are distinguished by their notably low TiO2 contents (0.3-1.0?wt%) and coupling of high Nb/Y with low Zr/Y and Sm/Yb. Relatively high CaO and low Zn/Fe point to a peridotitic mantle source. Contamination-sensitive incompatible element ratios show that one lava flow is likely to be uncontaminated by the crust and its composition suggests a mantle source with primitive mantle-like incompatible element ratios and mildly depleted isotopic ratios (initial 87Sr/86Sr?=?0.7041 and eNd?=?+1.4 at 180?Ma). The primary melts of the Luenha picrites had MgO contents in the range of 13-21?wt%. Our preferred estimate for a primary melt composition (MgO?=?18?wt%) resembles experimental melts of fertile mantle peridotite at 3-4?GPa and indicates liquidus temperature of 1445-1582?°C. Geochemical similarities suggest the Luenha picrites were generated from the same overall primitive mantle-like reservoir that produced the main volume of Karoo flood basalts in the Karoo, Kalahari, and Zambezi basins, whereas the previously identified enriched and depleted (upper) mantle sources of Karoo picrite suites (Mwenezi, Antarctica) were subordinate sources for flood basalts. We propose that the Luenha picrites record melting of a hot, chemically primitive mantle plume source that may have been rooted in the sub-African large low shear velocity province boundary and that such a source might have been the most significant magma source in the Karoo LIP.
DS200912-0333
2009
Jamasmie, C.Jamasmie, C.Nunavut: the epicentre of a new diamond exploration boom in Canada. Peregrine features. Stornoway mentioned.Mining Magazine, July pp. 16-17.Canada, NunavutNews item - Peregrine
DS200812-0637
2008
Jambion, A.Le Guillou, C., Rouzaud, J.N., Bourot-Denise, M., Remusat, L., Jambion, A.Laboratory shock synthesized diamond vs carbons from a differentiated meteorite.Goldschmidt Conference 2008, Abstract p.A532.Urelilite
DS1998-0512
1998
JambonGillet, Ph., Matas, Fiquet, Chamorro, Maryinez, JambonVolatiles in the Earth's mantle: insights from mineral and melt physicsMineralogical Magazine, Goldschmidt abstract, Vol. 62A, p. 521-2.MantleMagnesite, noble gases, volcanism.
DS1987-0441
1987
Jambon, A.Marty, B., Jambon, A.C/3He in volatile fluxes from the solid earth: implications for carbongeodynamicsEarth and Planetary Science Letters, Vol. 83, No. 1-4, May pp. 16-26GlobalGeochemistry
DS1992-0358
1992
Jambon, A.Deruelle, B., Dreibus, G., Jambon, A.Iodine abundances in oceanic basalts: implications for earth dynamicsEarth and Planetary Science Letters, Vol. 108, No. 4, February pp. 217-228GlobalGeochemistry, Oceanic basalts
DS1994-0287
1994
Jambon, A.Chaussidon, M., Jambon, A.Boron content and isotopic composition of oceanic basalts: geochemical and cosmochemical implicationsEarth and Planetary Science Letters, Vol. 121, pp. 277-291MantleOceanic basalts, Geochronology -boron
DS1998-0680
1998
Jambon, A.Jambon, A., Gillet, P., Chamorro, ColticeHelium and argon poor magmas from the under gassed mantleMineralogical Magazine, Goldschmidt abstract, Vol. 62A, p. 705-6.Hawaii, Mantlehelium, Geodynamics
DS2002-0105
2002
Jambon, A.Barrat, J.A., Jambon, A., Bohn, M., Gillet, P., Sautter, V., Gopei, C., Lesourd, M.Petrology and chemistry of the picritic shergottite north west AfricaGeochimica et Cosmochimica Acta, Vol.66, 19, pp.3505-18.West AfricaPicrites
DS201012-0323
2010
Jambon, Agrinier.DavailleJavoy, M., Kaminski, E., Guyot,Andrault, Sanloup, Moreira, Labrosse, Jambon, Agrinier.Davaille, JaupartThe chemical composition of the Earth: enstatite chondrite models.Earth and Planetary Science Letters, Vol. 293, 3-4, pp. 259-268.MantleChemistry
DS1990-0753
1990
Jambor, J.L.Jambor, J.L., Vaughan, D.J.Advanced microcopic studies of ore mineralsMineralogical Association of Canada Short Course Handbook, Vol. 17, 440pBookMicroscopy -ore minerals
DS1990-0754
1990
Jambor, J.L.Jambor, J.L., Vaughan, D.J.Advanced mircorscopic studies of ore mineralsMineralogical Association of Canada Short Course Handbook, Vol. 17, 440pGlobalBook -table of contents, Microscopy -ore minerals
DS1992-1411
1992
Jambor, J.L.Sinclair, W.D., Jambor, J.L., Birkett, T.C.Rare earths and the potential for rare earth deposits in CanadaThe Canadian Institute of Mining, Metallurgy and Petroleum (CIM) Exploration and Mining Geology, Vol. 1, No. 3, July pp. 265-282CanadaEconomics, overview, Rare earths
DS1993-1472
1993
Jambor, J.L.Sinclair, W.D., Jambor, J.L., Birkett, T.C.Rare earth deposits in Canada: alkaline complexes as potential sources of rare earth elements.Rare earth Minerals: chemistry, origin and ore deposits, International Geological Correlation Programme (IGCP) Project, pp. 128-130. abstractCanadaAlkaline rocks, rare earth elements (REE).
DS1994-0172
1994
Jambor, J.L.Blowes, D.W., Jambor, J.L.The environmental geochemistry of sulfide mine wastesMineralogical Association of Canada Short Course, Vol. 22, 110p. $ 30.00GlobalEnvironmental geochemistry, Table of contents, Mine wastes
DS2003-0063
2003
Jambor, J.L.Baker, M.J., Blowes, D.W., Logsdon, M.J., Jambor, J.L.Environmental geochemistry of kimberlite materials: Diavik diamonds project, Lac deExploration Mining Geology ( C.I.M.), Vol. 10, 3, pp. 155-63.Northwest TerritoriesGeochemistry - whole rock analyses, ABA results, Deposit - Diavik
DS200412-0086
2003
Jambor, J.L.Baker, M.J., Blowes, D.W., Logsdon, M.J., Jambor, J.L.Environmental geochemistry of kimberlite materials: Diavik diamonds project, Lac de Gras, Northwest Territories, Canada.Exploration Mining Geology , Vol. 10, 3, pp. 155-63.Canada, Northwest TerritoriesGeochemistry - whole rock analyses, ABA results Deposit - Diavik
DS201312-0849
2013
Jambor, J.L.Smith, L.J.D., Blowes, D.W., Jambor, J.L., Smith, L., Sego, D.C., Neuner, M.The Diavik waste rock project: initial geochemical response from a low sulfide waste rock pile.Applied Geochemistry, Vol. 36, pp. 200-209.Canada, Northwest TerritoriesMining - Diavik
DS2001-0325
2001
JamesFouch, M.J., James, Silver, VanDecar, Van der LeeImaging broad ranges in structural variations beneath the Kaapvaal and Zimbabwe Cratons, southern Africa.Slave-Kaapvaal Workshop, Sept. Ottawa, 5p. abstractSouth Africa, ZimbabweGeophysics - seismics, Tomography - Kimberley array
DS2001-0644
2001
JamesKwadiba, M., Wright, James, Kgaswane, Simon, Niu, SchuttCrustal phases and the structure of the crust beneath the Kaapvaal CratonSlave-Kaapvaal Workshop, Sept. Ottawa, 2p. abstractSouth AfricaTectonics, Geophysics - teleseismic
DS2001-0832
2001
JamesNguuri, T.K., Gore, James, Webb, Wright, Zengeni et al.Crustal structure beneath southern Africa and its implications for the formation and evolution of ...Geophysical Research Letters, Vol. 28, No. 13, July 1, pp. 2501-4.South AfricaTectonics, Craton - Kaapvaal and Zimbabwe
DS2001-1069
2001
JamesShirey, S.B., Harris, James, Deines, Richardson, et al.Geochemical and geophysical perspectives on diamond formation beneath southern Africa.Slave-Kaapvaal Workshop, Sept. Ottawa, 3p. abstractSouth AfricaGeochemistry - diamond inclusions, Diamond - genesis
DS2001-1182
2001
JamesVan der Lee, S., Van De Car, Fouch, JamesCombined sensitivity to the Kaapvaal tectosphere of regional and teleseismic surface and S Waves.Slave-Kaapvaal Workshop, Sept. Ottawa, 3p. abstractSouth AfricaGeophysics - seismics, Lithosphere
DS200712-0769
2006
JamesNadeau, L., Ryan, J.J., Hinchey, A.M., James, Sandeman, Tremblay, Schetselaar, Berman, DavisOutlook on the geology of the Boothia MaIn land area, Kitikmeot region, Nunavut.34th Yellowknife Geoscience Forum, p. 39-40. abstractCanada, NunavutGeology - brief overview
DS1996-0676
1996
James, C.James, C.Structuring Win/Win joint ventures ( eg. with Echo Bay)Southeast Asian Mining Conference, Sept. Toronto, 8p (slide diagrams not text)GlobalEconomics, Joint Ventures -alliances
DS1988-0218
1988
James, D.Fitton, J.G., James, D., Kempton, P.D., Ormerod, D.S., Leeman, W.P.The role of lithospheric mantle in the generation of late Cenozoic basic magmas in the Western UnitedStatesJournal of Petrology, Special Volume 1988- Oceanic and Continental, pp. 331-349United States, Colorado PlateauHopi Buttes
DS1995-0398
1995
James, D.Dawson, J.B., James, D., Paslick, m C., Halliday, A.Thermal anomay in the upper mantle beneath a propagating continental rift:evdience Labait VolcanoProceedings of the Sixth International Kimberlite Conference Extended Abstracts, p. 124-5.TanzaniaTectonics, magmatism, Carbonatite
DS1995-0870
1995
James, D.James, D., Christie, B.The Canadian diamond sector.. a sparkling new industry groupCanaccord, Oct. 19, 12p.Northwest Territories, Brazil, SaskatchewanNews item -research report, Aber, Canabrava, Dia Met, Kensington, Mountain Province
DS1995-1444
1995
James, D.Paslick, C., Halliday, A., James, D., Dawson, J.B.Enrichment of the continental lithosphere by Ocean Island Basalt (OIB) melts: isotopic evidence from volcanic province, Tanzania.Earth and Planetary Science Letters, Vol. 130, No. 1-4, Feb. pp. 109-126.TanzaniaGeochronology, Volcanics
DS2000-0440
2000
James, D.James, D., Fouch, M., Vandecar, J.Seismic studies of lithsopheric structure beneath southern Africa: implications for formation cratons...Geological Society of America (GSA) Abstracts, Vol. 32, No. 7, p.A-163.South AfricaCraton - evolution Kaapvaal, Geophysics - seismics
DS2001-0526
2001
James, D.James, D., Boyd, Bell, Schutt, CarlsonXenolith constraints on seismic velocities in the upper mantle beneath southern Africa.Slave-Kaapvaal Workshop, Sept. Ottawa, 2p. abstractSouth Africa, BotswanaGeophysics - seismics, Tomography - Kaapvaal Craton
DS2001-0527
2001
James, D.James, D., Rokosky, Nguuri, Gore, Niu, WebbCrustal formation in the Archean: constraints from the southern Africa seismic experiment.Slave-Kaapvaal Workshop, Sept. Ottawa, 2p. abstractSouth Africa, BotswanaGeophysics - seismics, Brief review of crustal structure studies
DS2001-1199
2001
James, D.Ven der Lee, S., James, D., Silver, P.Upper mantle S velocity structure of central and south AmericaJournal of Geophysical Research, Vol. 106, No. 12, pp. 30,821-34.South AmericaTectonics, Geophysics
DS2001-1226
2001
James, D.Wen. L., Silver, P., James, D., Kuehnel, R.Seismic evidence for a thermo chemical boundary at the base of the Earth'smantle.Earth and Planetary Science Letters, Vol. 189, No. 3-4, July 15, pp. 141-54.MantleGeophysics - seismics, Boundary
DS200412-0477
2004
James, D.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
DS1994-0824
1994
James, D.E.James, D.E.P and S seismic velocities in the upper mantle transition zone beneath The western Brazilian shield.International Symposium Upper Mantle, Aug. 14-19, 1994, pp. 124-126.BrazilGeophysics -seismics, Mantle
DS1994-0825
1994
James, D.E.James, D.E.Structure and dynamics of the continental lithosphere: a reviewInternational Symposium Upper Mantle, Aug. 14-19, 1994, pp. 151-164.Canada, Superior ProvinceGeodynamics, Lithosphere, orogeny, Trans Hudson
DS1994-0826
1994
James, D.E.James, D.E., Snoke, J.A.Structure and tectonics in the region of flat subduction beneath centralPeru: crust and uppermost mantleJournal of Geophy. Research, Vol. 99, No. B4, April 10, pp. 6899-6912PeruTectonics, Structure
DS1994-1647
1994
James, D.E.Snoke, J.A., James, D.E.Structure of the continental lithosphere beneath southeast Brasil from surfacewave inversion: prel. results.International Symposium Upper Mantle, Aug. 14-19, 1994, pp. 121-123.BrazilTectonics, Lithosphere
DS1998-0681
1998
James, D.E.James, D.E., et al.Review of seismic structure of the continental lithosphere with results from the Southern Africa....7th International Kimberlite Conference Abstract, pp. 366-70.South AfricaGeophysics - seismics, Tomography, discontinuity, anistrophy structure
DS2001-0528
2001
James, D.E.James, D.E., Fouch, D.J., Van De Car, M.J., VanderleeTectosphere structure beneath southern AfricaGeophysical Research Letters, Vol. 28, No. 13, July 1, pp. 2485-88.South AfricaTectonics
DS2002-0761
2002
James, D.E.James, D.E., Fouch, M.J.Formation and evolution of Archean cratons: insights from southern AfricaGeological Society of London Special Publication, No. 199, pp. 1-26.South AfricaTectonics
DS2002-1144
2002
James, D.E.Niu, F., James, D.E.Fine structure of the lowermost crust beneath the Kaapvaal Craton and its implication for crustal formation and evolution.Earth and Planetary Science Letters, Vol. 200, 1-2, pp. 121-30.South AfricaTectonics
DS2002-1465
2002
James, D.E.Shirey, S.B., Harris, J.W., Richardson, S.H., Fuch, M.J., James, D.E., CartignyDiamond genesis, seismic structure and evolution of the Kaapvaal Zimbabwe CratonScience, No. 5587, Sept. 6, pp. 1683-5.South Africa, ZimbabweTectonics - diamond genesis, Geophysics - seismics
DS2003-0644
2003
James, D.E.James, D.E.Imaging crust and upper mantle beneath southern Africa: the southern Africa broadbandLeading Edge, Vol. 22, 3, pp. 238-49.South AfricaGeophysics - seismics
DS2003-0645
2003
James, D.E.James, D.E., Niu, F., Rokosky, J.Crustal structure of the Kaapvaal craton and its significance for early crustal evolutionLithos, Vol. 71, 2-4, pp. 413-429.South AfricaGeophysics - seismics, tectonics
DS2003-1267
2003
James, D.E.Shirey, S.B., Harris, J.W., Richardson, S.H.,Fouch, M., James, D.E., CartignyRegional patterns in the paragenesis and age of inclusions in diamond, diamondLithos, Vol. 71, 2-4, pp. 243-258.South AfricaDiamond inclusions
DS200412-0567
2004
James, D.E.Fouch, M.J., James, D.E., Van De Car, J.C., Van Der Lee, S.Mantle seismic structure beneath the Kaapvaal and Zimbabwe Cratons.South African Journal of Geology, Vol. 107, 1/2, pp. 33-44.Africa, South Africa, ZimbabweGeophysics - seismics, tectonics, magmatism
DS200412-0901
2003
James, D.E.James, D.E.Imaging crust and upper mantle beneath southern Africa: the southern Africa broadband seismic experiment.Leading Edge, Vol. 22, 3, pp. 238-49.Africa, South AfricaGeophysics - seismics
DS200412-0902
2003
James, D.E.James, D.E., Niu, F., Rokosky, J.Crustal structure of the Kaapvaal craton and its significance for early crustal evolution.Lithos, Vol. 71, 2-4, pp. 413-429.Africa, South AfricaGeophysics - seismics, tectonics
DS200412-1439
2004
James, D.E.Niu, F., Levander, A., Cooper, C.M., Lee, C.T., Lenardic, A., James, D.E.Seismic constraints on the depth and composition of the mantle keel beneath the Kaapvaal craton.Earth and Planetary Science Letters, Vol. 224, 3-4, pp. 337-346.Africa, South AfricaGeophysics - seismics, boundary
DS200412-1806
2003
James, D.E.Shirey, S.B., Harris, J.W., Richardson, S.H.,Fouch, M., James, D.E., Cartigny, P.,Deines, P., Vijoen, F.Regional patterns in the paragenesis and age of inclusions in diamond, diamond composition and the lithospheric seismic structurLithos, Vol. 71, 2-4, pp. 243-258.Africa, South AfricaDiamond inclusions
DS200512-0140
2005
James, D.E.Carlson, R.W., Pearson, D.G., James, D.E.Physical, chemical and chronological characteristics of continental mantle.Reviews of Geophysics, Vol. 43, 1, RG1001 10.1029/2004 TG000156MantleGeochemistry
DS200612-0766
2006
James, D.E.Larson, A.M., Snoke, J.A., James, D.E.S-wave velocity structure, mantle xenoliths and the upper mantle beneath the Kaapvaal Craton.Geophysical Journal International, Vol. 167, 1, Oct., pp. 171-186.Africa, South AfricaGeophysics - seismics
DS201012-0245
2010
James, D.E.Gore, J., James, D.E., Zengeni, T.G., Gwavava, O.Crustal structure of the Zimbabwe craton and the Limpopo belt of southern Africa: new constraints from seismic dat a and implications for its evolution.South African Journal of Geology, Vol. 112, pp. 213-228.Africa, Zimbabwe, South Africa, BotswanaGeophysics - seismics
DS1989-0698
1989
James, D.R.James, D.R.Claude Resources Inc. (CRJ) -$ 4.50 Diamonds inSaskatchewan. Special situation reportRichardson Greenshields Equity Research, No. 89-102, August 10, 1989, 10pSaskatchewanCompany profile, Claude-Corona
DS1992-0769
1992
James, D.R.James, D.R.Diamonds in the North Lac de Gras, Northwest Territories diamond playRichardson Greenshields Equity Research, No. 92-79, May 28, 10pNorthwest TerritoriesNews item, BHP, Dia Met
DS1993-0735
1993
James, D.R.James, D.R.Diamond mining at Lac de Gras Northwest Territories... The race is onRichardson Greenshields Equity Research, No. 93-167, October 20, 19p.Northwest TerritoriesResearch Report, Dia Met, BHP
DS1996-0677
1996
James, D.R.James, D.R.The Canadian diamond sector.. an update on selected exploration/developmentprojects.Canaccord, May 30, pp. 1-8.Northwest Territories, Ontario, SaskatchewanBrief overview, Diamond exploration
DS1995-0345
1995
James, D.T.Connelly, J.N., Rivers, T., James, D.T.Thermotectonic evolution of the Grenville Province of western LabradorTectonics, Vol. 14, No. 1, February pp. 202-217Labrador, QuebecTectonics, Terranes
DS1995-0346
1995
James, D.T.Connelly, J.N., Rivers, T., James, D.T.Thermotectonic evolution of the Grenville Province of western LabradorTectonics, Vol; . 14, No. 1, Feb. pp. 202-217.Labrador, Ungava, QuebecTectonics
DS1996-0678
1996
James, D.T.James, D.T., Connelly, J.N., Wasteneys, H.A., Kilfoil, G.J.Paleoproterozoic lithotectonic divisions of the southeastern ChurchillProvince, western LabradorCanadian Journal of Earth Sciences, Vol. 33, No. 2, Feb. pp. 216-230Labrador, Quebec, UngavaTectonics, Geochronology, Nain Craton, Superior Craton
DS2000-0441
2000
James, D.T.James, D.T., Duning, G.R.uranium-lead (U-Pb) geochronological constraints for Paleoproterozoic evolution of the Core Zone, southeastern Churchill ProvPrecambrian Research, Vol. 103, No. 1-2, Sept. pp. 31-54.Saskatchewan, Manitoba, Western CanadaGeochronology, Churchill Province
DS2000-0442
2000
James, D.T.James, D.T., Dunning, G.R., Fairchild, T.R.Proterozoic microfossils from subsurface siliclastic rocks of the Sao Francico Craton, south central Brasil.Precambrian Research, Vol. 103, No. 1-2, Sept.pp. 31-54.Brazil, south centralCraton - Sao Francisco
DS2001-0529
2001
James, D.T.James, D.T.Paleoproterozoic (>1.75) crustal growth and architecture in the region between Superior ....Geological Association of Canada (GAC) Annual Meeting Abstracts, Vol. 26, p.71, abstract.Quebec, LabradorTectonics - New Quebec orogen, North Atlantic Craton - a review
DS2001-0530
2001
James, D.T.James, D.T., Ryan, A.B.The Saglek and Hopedale blocks of the Western North Atlantic Craton: a review of 1.4 Billion years evol.Geological Association of Canada (GAC) Annual Meeting Abstracts, Vol. 26, p.71, abstract.Quebec, LabradorTectonics, Geochronology
DS2002-0762
2002
James, D.T.James, D.T., Kamo, S., Krogh, T.Evolution of 3.1 and 3.0 Ga volcanic belts and a new thermotectonic model for the Hopedale Block, North Atlantic Craton, Canada.Canadian Journal of Earth Science, Vol.39,5, May, pp.687-710.Quebec, Labrador, GreenlandTectonics - regional framework
DS2002-1688
2002
James, D.T.Wardle, R.J., James, D.T., Scott, D.J., Hall, J.The southeastern Churchill Province: synthesis of a Paleoproterozoic transpressional orogen.Canadian Journal of Earth Science, Vol.39,5, May, pp.639-63.Quebec, Labrador, Baffin IslandGeophysics - Torngat, New Quebec orogens, Trans Hudson, Tectonics - Nain, Superior Craton
DS200812-0973
2007
James, D.T.Ross, M., Utting, D.J., Hodgson, D.A., James, D.T.Ice flow and dispersal patterns on Southampton Island Nunavut: a preliminary Assessment. ( KIMs)35th. Yellowknife Geoscience Forum, Abstracts only p. 52.Canada, NunavutGeochemistry - samples
DS200812-0998
2008
James, D.T.Sanborn-Barrie, M., Chakungal, J., James, D.T., Whalen, J., Rayner, N., Berman, R.G., Craven, J., Coyle, M.New understanding of the geology and diamond prospectivity of Southampton Island, central Nunavut.Northwest Territories Geoscience Office, p. 53-54. abstractCanada, NunavutDeposit - Qilalugaq
DS201012-0797
2009
James, D.T.Tremblay, T., Ryan, J.J., James, D.T., Kjarsgaard, I.M.Kimberlite indicator mineral survey and ice flow studies in Boothia maIn land 57A,B,C,D. Kitikmeot region, Nunavut.Geological Survey of Canada, Open file 6040 31p. CD $ 9.10Canada, NunavutGeochemistry
DS1993-0736
1993
James, E.W.James, E.W., Henry, C.D.Southeastern extent of the North American craton in Texas and northern Chihuahua as revealed by lead isotopesGeological Society of America (GSA) Bulletin, Vol. 105, No. 1, January pp. 116-126Texas, MexicoCraton, tectonics
DS1992-0770
1992
James, H.L.James, H.L.Precambrian iron formations: nature, origin and mineralogic evolution from sedimentation to metamorphismin: Diagenesis III, editors Wolf, K.H., Chilingarian, G.V, Vol. 11, pp. 543-589GlobalIron Formations -Precambrian, Nature, origin and mineralogy
DS1960-0560
1965
James, L.D.James, L.D.Regional Geochemical Reconnaissance in the Northern and Southern Sections of the Sula Mountains Schist Belt.London: Ph. D. Thesis, University London., 401P.Sierra Leone, West Africa, Kangari HillsGeochemistry, Regional Studies, Chromite
DS1960-0719
1966
James, L.D.Nicol, I., James, L.D., Viewing, K.D.Regional Geochemical Reconnaissance in Sierra LeoneInstitute of Mining and Metallurgy. Transactions, Vol. 75, PP. B146-161.Sierra Leone, West AfricaGeochemistry, Kimberlite, Diamonds
DS1991-1325
1991
James, N.P.Pelechaty, S.M., James, N.P., Kerans, C., Grotzinger, J.P.A middle Proterozoic paleokarst unconformity and associated sedimentaryrocks, Elu basin, Northwest CanadaSedimentology, Vol. 38, No. 5, October pp. 775-798Northwest TerritoriesBasin, Proterozoic
DS2003-0862
2003
James, P.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
James, P.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
DS200512-0115
2004
James, R.H.Brooker, R.A., James, R.H., Blundy, J.D.Trace elements and Li isotope systematics in Zabargad peridotites: evidence of ancient subduction processes in the Red Sea mantle.Chemical Geology, Vol. 212, 1-2, pp. 179-204.Mantle, EuropeSubduction
DS200712-0407
2007
James, R.H.Hammond, S.J., Parkinson, I.J., James, R.H., Rogers, N.W., Harvey, J.Delta 7 Li systematics of mantle xenoliths from Kilbourne Hole: unravelling metasomatic and differential processes.Plates, Plumes, and Paradigms, 1p. abstract p. A373.United States, New Mexico, Colorado PlateauMetasomatism
DS1991-1320
1991
James, R.S.Peck, D.C., James, R.S.Geology and platinum group element sulphide mineralization, East BulletinLakeOntario Geological Survey Open File, Report No. 5813, 65pOntarioPlatinuM., Deposit -East Bulletin Lake
DS1995-0318
1995
James, R.S.Chubb, P.T., Peck, D.C., James, R.S., Ercit, T.S.Nature and origin of nodular textures in anorthositic cumulates from the east Bulletin intrusion, OntarioMineralogy and Petrology, Vol. 54, No. 1-2, pp. 93-104OntarioAnorthosites, layered intrusion, Deposit -East Bulletin
DS1998-1549
1998
James, R.S.Vogel, D.C., Vuollo, J.I., James, R.S.Tectonic, stratigraphic and geochemical comparisons between ca 2500-2440 Mamafic igneous events - shield.Precambrian Research, Vol. 92, No. 2, Oct.l, pp. 89-116Canada, FennoscandiaTectonics - shield, Geochemistry
DS1998-1550
1998
James, R.S.Vogel, D.C., Vuollo, J.I., James, R.S.Tectonic, stratigraphic and geochemical comparisons between 2500-2440 Mamafic igneous events ...shieldPrecambrian Research, Vol. 92, No. 2, Oct. 1, pp. 89-116.Canada, FennoScandia, Finland, DenmarkTectonics - shield, Geochemistry
DS1992-0888
1992
James, S.D.Kostopoulos, D.K., James, S.D.Parameterization of melting regime of shallow upper mantle and effects of variable lithospheric stretching on mantle modal stratification, trace elementmagmasJournal of Petrology, Vol. 33, No. 3, pp. 665-691MantleModel, Upper mantle -magmas
DS1994-1806
1994
James, T.Turner, B.L., James, T.Developing a diamond mine: sequence versus synchronismThe Canadian Institute of Mining, Metallurgy and Petroleum (CIM) District 6, Oct. 11-15th. Vancouver, p.66 abstract onlyNorthwest TerritoriesEnvironment, Land management
DS1950-0395
1958
James, T.C.James, T.C., Mckie, D.The Alteration of Pyrochlore to Columbite in Carbonatites In Tanganyika.Mineralogical Magazine., Vol. 31, No. 242, SEPT. PP. 889-907.Tanzania, East AfricaMineralogy
DS1992-0771
1992
James, T.S.James, T.S.The Hudson Bay free-air gravity anomaly and glacial reboundGeophysical Research Letters, Vol. 19, No. 9, May 4, pp. 861-864OntarioGeophysics-gravity, Geomorphology
DS1991-1149
1991
James, W.C.Mickus, K.L., James, W.C.Regional gravity studies in southeastern California, western Arizona, and southern NevadaJournal of Geophysical Research, Vol. 96, No. B7, July 10, pp. 12, 333-12, 351Arizona, NevadaStructure, Geophysics -gravity
DS1992-0974
1992
James, W.C.Mack, G.H., James, W.C.Paleosols for sedimentologistsGeological Society of America Short Course, Notes, 125pGlobalShort Course, Sedimentology, paleosols
DS1993-0949
1993
James, W.C.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
James, W.C.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
James, W.C.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
DS1982-0296
1982
James Capel And CoJames Capel And CoThe World Diamond IndustryLondon: James Capel And Co., NOT KNOWN.GlobalKimberley, Mineral Economics, Markets, Cso, Industry Review
DS1998-1594
1998
JamiesonWu, W.J., Lines, L., Burton, Lu, Zhu, Jamieson, BordingPrestack depth migration of an Alberta foothills dat a set: the Husky experience.Geophysics, Vol. 63, No. 2, pp. 392-8.AlbertaGeophysics - seismics, Tectonics, thrust
DS201312-0435
2013
Jamieson, A.Jamieson, A., Beaumont, C.On the origin of orogens.Geological Society of America Bulletin, Vol. 125, pp. 1671-1702.TechnologyOrogen
DS1990-0755
1990
Jamieson, B.Jamieson, B.De Beers coup spurs the rush to RussiaSunday Telegraph, July 29, 1/4pRussiaNews item, De Beers and Russia
DS1990-0756
1990
Jamieson, B.Jamieson, B.Red alert as the Soviet Union's diamonds come in from the coldSunday Telegraph, July 29, 1pRussiaNews item, De Beers and Russia
DS1960-0531
1965
Jamieson, B.G.Cox, K.G., Jamieson, B.G.Progress Report on Karroo Volcanic StudiesLeeds University Research Institute of African Geology Annual Report, Vol. 3B, PP. 37-39.South Africa, BotswanaGeology
DS2001-1000
2001
Jamieson, D.N.Ryan, C.G., Jamieson, D.N., Griffin, W.L., CrippsThe new CSIRO GEMOC nuclear microprobe: first results, performance and recent applications.Nuclear Institute Methods Phys. Res., Vol. B 181, pp. 12-19.GlobalProton microprobe
DS2003-1179
2003
Jamieson, H.E.Rolla, A., Jamieson, H.E.Processed kimberlite water interactions in diamond mine waste, Ekati diamond mineGeological Association of Canada Annual Meeting, Abstract onlyNorthwest TerritoriesMining - waste
DS2003-1180
2003
Jamieson, H.E.Rollo, H.A., Jamieson, H.E.Processes kimberlite - water interactions in diamond mine waste, Ekati diamond mine8ikc, Www.venuewest.com/8ikc/program.htm, Session 1 POSTER abstractNorthwest TerritoriesKimberlite geology and economics, Mining - tailings, environment
DS200412-1685
2003
Jamieson, H.E.Rolla, A., Jamieson, H.E.Processed kimberlite water interactions in diamond mine waste, Ekati diamond mine, N.W.T. Canada.Geological Association of Canada Annual Meeting, Abstract onlyCanada, Northwest TerritoriesMining - waste
DS200612-1172
2006
Jamieson, H.E.Rollo, H.A., Jamieson, H.E.Interaction of diamond mine waste and surface water in the Canadian Arctic.Applied Geochemistry, Vol. 21, 9, pp. 1522-1538.Canada, Northwest TerritoriesMining
DS200712-0609
2007
Jamieson, H.E.Lee, C.A., Rollo, H.A., Jamieson, H.E.Rock water interaction and CO2 sequestration associated with kimberlite ore processing.Geological Association of Canada, Gac-Mac Yellowknife 2007, May 23-25, Volume 32, 1 pg. abstract p.47.TechnologyMineral processing
DS201212-0315
2012
Jamieson, H.E.Hudson-Edwards, K.A., Jamieson, H.E., Lottermoser, B.G.Mine wastes: past present, future * not specific to diamond mines - good general knowledgeElements, Vol. 7, 6, Dec. pp. 375-380.GlobalDescription of mine wastes - history
DS201012-0045
2010
Jamieson, R.Beaumont, C., Jamieson, R., Nguyen, M.Models of large, hot orogens containing a collage of reworked and accreted terranes.Canadian Journal of Earth Sciences, Vol. 47, 4, pp. 485-515.MantleCraton
DS1991-0327
1991
Jamieson, R.A.Culshaw, N., Corrigan, D., Jamieson, R.A., Ketchum, J., Wallace, P.Traverse of the Central Gneiss Belt, Grenville Province, Georgian Bay, OntarioGeological Association of Canada (GAC) Annual Meeting held Toronto May 1991, Guidebook, No. B3, 35pOntarioCentral Gneiss Belt, Structure
DS1997-0233
1997
Jamieson, R.A.Culshaw, N.G., Jamieson, R.A., Ketchum, J.W.F., et al.Transect across the northwestern Grenville orogen, Georgian Bay Ontario:polystage convergence.. extensionTectonics, Vol. 16, No. 6, Dec. pp. 966-982.OntarioTectonics, Lower Orogenic Crust
DS2000-0443
2000
Jamieson, R.A.Jamieson, R.A., Beaumont, Vanderhaeghe, FullsackHow does the lower crust get hot?Geological Association of Canada (GAC)/Mineralogical Association of Canada (MAC) 2000 Conference, 2p. abstract.MantleMagma - heat production
DS2002-0763
2002
Jamieson, R.A.Jamieson, R.A., Beaumont, C., Nguyen, M.H., Lee, B.Interaction of metamorphism, deformation and exhumation in large convergent orogensJournal of Metamorphic Geology, Vol.20,1,pp. 9-24.GlobalOrogens - tectonics - not specific to diamonds
DS2003-1409
2003
Jamieson, R.A.Van der Hagaeghe, O., Medvedev, S., Fullsack, P., Beaumont, C., Jamieson, R.A.Evolution of orogenic wedges and continental plateaux: insights from crustalGeophysical Journal International, Vol. 153, 1, pp. 27-51.MantleGeothermometry, Subduction
DS200412-2035
2003
Jamieson, R.A.Van der Hagaeghe, O., Medvedev, S., Fullsack, P., Beaumont, C., Jamieson, R.A.Evolution of orogenic wedges and continental plateaux: insights from crustal thermalmechanical models overlying subducting mantlGeophysical Journal International, Vol. 153,1, pp. 27-51.MantleGeothermometry Subduction
DS200612-0297
2006
Jamieson, R.A.Culshaw, N.G., Beaumont, C., Jamieson, R.A.The orogenic superstructure infrastructure concept: revisited, quantified, and revived.Geology, Vol. 34, 9, Sept. pp. 733-736.Canada, Ontario, Manitoba, Superior ProvinceTectonics, geophysics - seismics
DS200812-1242
2008
Jamieson, R.A.Warren, C.J., Beaumont, C., Jamieson, R.A.Modelling tectonic styles and ultra high pressure UHP rock exhumation during the transition from oceanic subduction to continental collision.Earth and Planetary Science Letters, Vol. 267, 1-2, pp.129-145.MantleSubduction
DS200812-1243
2008
Jamieson, R.A.Warren, C.J., Beaumont, C., Jamieson, R.A.Deep subduction and rapid exhumation: role of crustal strength and strain weakening in continental crust and ultrahigh pressure rock exhumation.Tectonics, Vol. 27, TC6002.MantleSubduction
DS200912-0040
2009
Jamieson, R.A.Beaumont, C., Jamieson, R.A., Butler, J.P., Warren, C.J.Crustal structure: a key constraint on the mechanism of ultra high pressure rock exhumation.Earth and Planetary Science Letters, Vol. 287, 1-2, pp. 116-129.MantleUHP
DS201112-0475
2011
Jamieson, R.A.Jamieson, R.A., Unsworth, M.J., Harris, N.B.W., Rosenberg, C.L., Schulmann, K.Crustal melting and the flow of mountains.Elements, Vol. 7, 4, August pp. 253-260.Mantle, AsiaCrustal deformation - weakening
DS201212-0099
2012
Jamieson, R.A.Butler, J.P., Jamieson, R.A., Steenkamp, H.M., Robinson, P.Discovery of coesite eclogite from the Nordyane UHP domain, Western Gneiss region, Norway: field relations, metamorphic history and tectonic significance.Journal of Metamorphic Geology, in press availableEurope, NorwayCoesite
DS201412-0423
2013
Jamieson, R.A.Jamieson, R.A., Beaumont, C.On the origin of orogens.Geological Society of America Bulletin, Vol. 125, pp. 1671-1702.TechnologyOrogen
DS201805-0941
2018
Jammes, S.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.
DS1996-0121
1996
Jams, W.J.Berger, A.R., Jams, W.J.Geoindicators - assessing rapid environmental changes in earth systemsBalkema, 470pGlobalEnvironment, water systems, semi, arid, Table of contents
DS2000-0955
2000
JamtveitTorsvik, T.H., Tucker, R.D., Ashwal, Carter, JamtveitLate Cretaceous India Madagascar fit and timing of break up related magmatisnTerra Nova, Vol. 12, No. 5, Oct. pp. 220-4.India, Madagascar, GondwanaGeochronology, Gondwana, tectonics
DS1996-0679
1996
Jamtveit, B.Jamtveit, B., Yardley, B.Fluid flow and transport in rocks: mechanisms and effectsChapman and Hall, ITP Distributors, approx. 150.00GlobalBook -ad, Sedimentary basins, fluid flow
DS1998-1430
1998
Jamtveit, B.Svensen, H., Jamtveit, B., Yardley, B., Austrheim, H.Eclogite facies fluids from the Caledonides of western Norway: compositions and implications for fluid-rock...Mineralogical Magazine, Goldschmidt abstract, Vol. 62A, p. 1481-2.NorwayEclogites, Fluid geochemistry
DS2001-1143
2001
Jamtveit, B.Svensen, H., Jamtveit, B., Austrheim, H.Halogen contents of eclogite facies fluid inclusions and minerals: Caledonides, western Norway.Earth and Planetary Science Letters, Vol. 186, No. 1, Mar. 15, pp.165-78.NorwayEclogites, Metasomatism
DS200512-0941
2005
Jamtveit, B.Schmalholz, S.M., Podladchikov, Y.Y., Jamtveit, B.Structural softening of the lithosphere.Terra Nova, Vol. 17, 1, pp. 66-72.MantleTectonics
DS1991-0024
1991
Jamveit, B.Andersen, T.B., Jamveit, B., Dewey, J.F., Swensson, E.Subduction and education of continental crust: major mechanisms during continent-continent collision and orogenic extensional collapse, a model Based on NorwegTerra Nova, Vol. 3, No. 3, pp. 303-310NorwayTectonics, Caledonides
DS201012-0320
2010
Jamveit, B.Jamveit, B.Metamorphism: from patterns to processes.Elements, Vol. 6, 3, pp. 149-152.MantleRates, systems
DS2001-0847
2001
Jan. M.O'Brien, P.J., Zotov, N., Law, R., Khan, M.A., Jan. M.Coesite in Himalayan eclogite and implications for models of India Asia collision.Geology, Vol. 29, No. 5, May, pp. 435-8.GlobalEclogite, coesite, metamorphism
DS1997-0550
1997
Jana, D.Jana, D., Walker, D.The impact of carbon on element distribution during core formationGeochimica et Cosmochimica Acta, Vol. 61, No. 13, pp. 2759-2763.GlobalSilicate partition, Carbon
DS201910-2241
2019
Jana, D.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.
DS201810-2372
2018
Janaina, N.Rielli A., Tomkins, A.G., Nebel, O., Raveggi, M., Jeon, H., Martin, L., Laure, A., Janaina, N.Sulfur isotope and PGE systematics of metasomatised mantle wedge.Earth and Planetary Science Letters, Vol. 497, 1, pp. 181-192.Mantlemetasomatism

Abstract: At convergent margins fluids liberated from subducting slabs metasomatise the overlying mantle wedge, enriching it in volatiles, incompatible elements and possibly ore-forming metals. Despite the genetic link between this process, the genesis of arc magmas, and formation of porphyry Cu-Au deposits, there is currently little understanding of the behaviour of chalcophile and siderophile elements during subduction-related mantle metasomatism. In this study, we report sulfur isotopic compositions and PGE concentrations of sulfides in a suite of garnet peridotites from the Western Gneiss Region of Norway, sampling mantle wedge from ~100 to ~250 km depth. Sulfides hosted in metasomatised samples have deviated from typical mantle values, ranging between -10.0 and +5.4‰, indicating derivation of sulfur from subducted crust. Sulfides in pervasively metasomatised samples have atypical PGE signatures, with strong enrichment in Os and Ru relative to Ir, whereas channelised fluid flow produced sulfides extremely enriched in Pd, up to 700 times the concentration found in non-metasomatised samples. These signatures are reconcilable with a high oxidation state of the metasomatising agents and demonstrate that subduction can recycle chalcophile and siderophile elements into and within the mantle, along with sulfur. We further show that because the solubility of Os and Ru in fluids is redox sensitive, and Pd is more soluble than the I-PGE, ratios such as Os/Ir, Ru/Ir plotted against Pd/Ir can be used to trace the metasomatic oxidation of mantle samples, mantle-derived magmas and porphyry Cu±Au deposits. This geochemical insight is used to show that Au-rich porphyry Cu deposits are derived from more oxidised mantle wedge than Au-poor porphyry deposits.
DS200612-1492
2006
Janak, M.Vrabec, M., De Hoog, J.C.M., Janak, M.Partial melting of zoisite eclogite and its significance for trace element cycling in subduction zones.Geochimica et Cosmochimica Acta, Vol. 70, 18, p. 14. abstract onlyMantleEclogite
DS200712-0226
2007
Janak, M.De Hoog, J.C.M., Janak, M., Vrabec, M.The role of zoisite in trace element distribution in subduction zones.Plates, Plumes, and Paradigms, 1p. abstract p. A211.Mantle, Alps, HimalayasSubduction
DS201312-0436
2013
Janak, M.Janak, M., Krogh Ravna, E.J., Kullerud, K., Yoshida, K., Milovsky, R., Hirajima, T.Discovery of diamond in the Tromso Nappe, Scandinavian Caledonides ( N. Norway).Journal of Metamorphic Geology, Vol. 31, 6, pp. 691-703.Europe, NorwayMicrodiamonds in gneiss
DS201502-0076
2014
Janak, 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
DS201503-0156
2015
Janak, M.Kotkova, J., Janak, M.UHP kyanite eclogite associated with garnet peridotite and diamond bearing granulite, northern Bohemian Massif.Lithos, Vol. 226, pp. 255-264.EuropeBohemian
DS201504-0203
2015
Janak, M.Janak, M., Froitzheim, N., Yoshida, K., Sasinkova, V., Nosko, M., Kobayashi,T., Hirajima, T., Vrabec, M.Diamond in metasedimentary crustal rocks from Pohorje, eastern Alps: a window to deep continental subductionJournal of Metamorphic Geology, Vol. 33, 5, pp. 495-512.Europe, SloveniaSubduction
DS201505-0237
2014
Janak, 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
DS201602-0230
2016
Janak, M.Petrik, I., Janak, M., Froitzheim, N., Georgiev, N., Yoshida, K., Sasinkova, V., Konecny, P., Milovska, S.Triassic to Early Jurassic (c.200 Ma) UHP metamorphism in the Central Rhodopes: evidence from U-Pb-Th dating of monazite in diamond bearing gneiss from Chelelpare, Bulgaria.Journal of Metamorphic Geology, in press available, 44p.Europe, BulgariaGneiss - diamonds

Abstract: Evidence for ultrahigh-pressure metamorphism (UHPM) in the Rhodope Metamorphic Complex comes from occurrence of diamond in pelitic gneisses, variably overprinted by granulite facies metamorphism, known from several areas of the Rhodopes. However, tectonic setting and timing of UHPM are not interpreted unanimously. Linking age to metamorphic stage is a prerequisite for reconstruction of these processes. Here we use monazite in diamond-bearing gneiss from Chepelare (Bulgaria) to date the diamond-forming UHPM event in the Central Rhodopes. The diamond-bearing gneiss comes from a strongly deformed, lithologically heterogeneous zone (Chepelare Mélange) sandwiched between two migmatized orthogneiss units, known as Arda-I and Arda-II. Diamond, identified by Raman micro-spectroscopy, shows the characteristic band mostly centred between 1332 and 1330 cm-1. The microdiamond occurs as single grains or polyphase diamond + carbonate inclusions, rarely with CO2. Thermodynamic modelling shows that garnet was stable at UHP conditions of 3.5-4.6 GPa and 700-800 °C, in the stability field of diamond, and was re-equilibrated at granulite facies/partial melting conditions of 0.8-1.2 GPa and 750-800 °C. The texture of monazite shows older central parts and extensive younger domains which formed due to metasomatic replacement in solid residue and/or overgrowth in melt domains. The monazite core compositions, with distinctly lower Y, Th and U contents, suggest its formation in equilibrium with garnet. The U-Th-Pb dating of monazite using electron microprobe analysis yielded a c. 200 Ma age for the older cores with low Th, Y, U and high La/Nd ratio, and a c. 160 Ma age for the dominant younger monazite enriched in Th, Y, U and HREE. The older age of around 200 Ma is interpreted as the timing of UHPM whereas the younger age of around 160 Ma as granulite facies/partial melting overprint. Our results suggest that UHPM occurred in Late Triassic to Early Jurassic time, in the framework of collision and subduction of continental crust after the closure of Palaeotethys.
DS201604-0621
2016
Janak, M.Petrik, I., Janak, M., Froitzheim, N., Georgiev, N., Yoshida, K., Sasinkova, V., Konecny, P., Milovska, S.Triassic to Early Jurassic ( c. 200Ma) UHP metamorphism in the Central Rhodopes: evidence from U-Pb dating of monazite in diamond bearing gneiss from Chepelare ( Bulgaria).Journal of Metamorphic Geology, Vol. 34, 3, pp. 265-291.Europe, BulgariaUHP diamond bearing gneiss
DS201606-1105
2016
Janak, M.Petrik, I., Janak, M., Froitzheim, N., Georgiev, N., Yoshida, K., Sasinkova, V., Konecny, P., Milovska, S.Triassic to Early Jurassic ( c. 200Ma) UHP metamorphism in the central Rhodopes: evidence from U-Pb-Th dating of monazite in diamond bearing gneiss from Chepelare Bulgaria.Journal of Metamorphic Geology, Vol. 34, 3, pp. 265-291.Europe, BulgariaDiamonds in gneiss
DS201702-0221
2017
Janak, M.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
Janak, M.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
Janak, M.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.
DS201805-0973
2017
Janak, M.Ravna, E.K., Zozulya, D., Kullerud, K., Corfu, F., Nabelek, P.I., Janak, M., Slagstad, T., Davidsen, B., Selbekk, R.S., Schertl, H-P.Deep seated carbonatite intrusion and metasomatism in the UHP Tromso Nappe, northern Scandinavian Caledonides - a natural example of generation of carbonatite from carbonated eclogite.Journal of Petrology, Vol. 58, 12, pp. 2403-2428.Europe, Sweden, Norwaycarbonatite

Abstract: Carbonatites (sensu stricto) are igneous rocks typically associated with continental rifts, being emplaced at relatively shallow crustal levels or as extrusive rocks. Some carbonatites are, however, related to subduction and lithospheric collision zones, but so far no carbonatite has been reported from ultrahigh-pressure (UHP) metamorphic terranes. In this study, we present detailed petrological and geochemical data on carbonatites from the Tromsø Nappe—a UHP metamorphic terrane in the Scandinavian Caledonides. Massive to weakly foliated silicate-rich carbonate rocks, comprising the high-P mineral assemblage of Mg-Fe-calcite?±?Fe-dolomite?+?garnet?+?omphacitic clinopyroxene?+?phlogopite?+?apatite?+?rutile?+?ilmenite, are inferred to be carbonatites. They show apparent intrusive relationships to eclogite, garnet pyroxenite, garnet-mica gneiss, foliated calc-silicate marble and massive marble. Large grains of omphacitic pyroxene and megacrysts (up to 5?cm across) of Cr-diopside in the carbonatite contain rods of phlogopite oriented parallel to the c-axis, the density of rods being highest in the central part of the megacrysts. Garnet contains numerous inclusions of all the other phases of the carbonatite, and, in places, composite polyphase inclusions. Zircon, monazite and allanite are common accessory phases. Locally, veins of silicate-poor carbonatite (up to 10?cm across) occur. Extensive fenitization by K-rich fluids, with enrichment in phlogopite along contacts between carbonatite and silicate country rocks, is common. Primitive mantle-normalized incompatible element patterns for the carbonatite document a strong enrichment of light rare earth elements, Ba and Rb, and negative anomalies in Th, Nb, Ta, Zr and Hf. The carbon and oxygen isotope compositions of the carbonatite are distinctly different from those of the spatially associated calc-silicate marble, but also from mantle-derived carbonatites elsewhere. Neodymium and Sr isotope data coupled with the trace element distribution indicate a similarity of the Tromsø carbonatite to orogenic (off-craton) carbonatites rather than to anorogenic (on-craton) ones. U-Pb dating of relatively U-rich prismatic, oscillatory-zoned zircon gives an age of 454•5?±?1•1?Ma. We suggest that the primary carbonatite magma resulted from partial melting of a carbonated eclogite at UHP, in a deeply subducted continental slab.
DS1994-1911
1994
Janardhan, A.S.Wickham, S.M., Janardhan, A.S., Stern, R.J.Regional carbonate alteration of the crust by mantle derived magmaticfluids, Tamil Nadu, South India.Journal of Geology, Vol. 102, No. 4, July, pp. 379-398.IndiaCarbonatite
DS201703-0396
2017
Janasi, V.A.Almeida, V.V., Janasi, V.A., Heaman, L.M., Shaulis, B.J., Hollanda, M.H.B.M., Renne, P.R.Contemporaneous alkaline and tholeiitic magmatism in the Ponta Grossa Arch, Parana Etendeka magmatic province: constraints from U-Pb zircon baddeleyite and 40Ar/39Ar phlogopite dating of the Jose Fernandes gabbro and mafic dykes.Journal of Volcanology and Geothermal Research, in press available 11p.South America, BrazilAlkaline rocks

Abstract: We report the first high-precision ID-TIMS U-Pb baddeleyite/zircon and 40Ar/39Ar step-heating phlogopite age data for diabase and lamprophyre dykes and a mafic intrusion (José Fernandes Gabbro) located within the Ponta Grossa Arch, Brazil, in order to constrain the temporal evolution between Early Cretaceous tholeiitic and alkaline magmatism of the Paraná-Etendeka Magmatic Province. U-Pb dates from chemically abraded zircon data yielded the best estimate for the emplacement ages of a high Ti-P-Sr basaltic dyke (133.9 ± 0.2 Ma), a dyke with basaltic andesite composition (133.4 ± 0.2 Ma) and the José Fernandes Gabbro (134.5 ± 0.1 Ma). A 40Ar/39Ar phlogopite step-heating age of 133.7 ± 0.1 Ma from a lamprophyre dyke is identical within error to the U-Pb age of the diabase dykes, indicating that tholeiitic and alkaline magmatism were coeval in the Ponta Grossa Arch. Although nearly all analysed fractions are concordant and show low analytical uncertainties (± 0.3-0.9 Ma for baddeleyite; 0.1-0.4 Ma for zircon; 2s), Pb loss is observed in all baddeleyite fractions and in some initial zircon fractions not submitted to the most extreme chemical abrasion treatment. The resulting age spread may reflect intense and continued magmatic activity in the Ponta Grossa Arch.
DS201412-0612
2014
Janasi, V.de A.Nannini, F., Janasi, V.de A.Prospeccao de depositos primarios de diamante por tomografia sismica: uma prosposta de integracao entre geologia e geofisica.6 Simposio Brasileiro de Geologia do Diamante, Aug. 3-7, 4p. AbstractSouth America, BrazilGeophysics - seismics
DS201709-2018
2017
Janek, M.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.
DS1986-0230
1986
Janes, D.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
DS1994-0827
1994
Janes, T.Janes, T.northwest Territories diamonds project: developmentThe Canadian Institute of Mining, Metallurgy and Petroleum (CIM) District 6, Oct. 11-15th. Vancouver, 9p.Northwest TerritoriesManagement, Project -sampling, development
DS1994-1805
1994
Janes, T.Turner, B., Janes, T.The BHP/ Dia Met joint venture, Northwest TerritoriesThe Canadian Institute of Mining, Metallurgy and Petroleum (CIM) Section Meeting Oct. 12, Vancouver, p. 66. abstractNorthwest TerritoriesUpdate, BHP, Dia Met
DS1993-1814
1993
Jang, J.Zhao, D., Smith, D.G.W. Smith, Zhou, M., Jang, J., Deng, C., Huang, Y.Yinniugou lamproites in Datong, northern Shanxi Province, Chin a: first occurrence in the North Chin a craton.Mid-continent diamonds Geological Association of Canada (GAC)-Mineralogical Association of Canada (MAC) Symposium ABSTRACT volume, held Edmonton May, pp. 133-140.ChinaLamproite, Craton, tectonics
DS200712-0482
2007
Jang, Y-H.Jang, Y-H., Jiang, S-Y., LHou, M-L., Ling, H.F., Zhao, K., Ni, P.Geochemistry of Late Mesozoic lamprophyre dikes from the eastern North Chin a Craton: implications for subcontinental lithosphere evolution.Plates, Plumes, and Paradigms, 1p. abstract p. A445.ChinaLamprophyre
DS200712-0738
2007
Jang-Green, H.Moe, K.S., Johnson, P., Jang-Green, H.Translucent greenish yellow diamonds.Gems & Gemology, Vol. 43, 1, pp. 50-53.TechnologyDiamond morphology
DS1998-0682
1998
Janiak, J.Janiak, J.Envi-Tech microdiamond recovery adsorption process for economic evaluation of diamond deposit.Calgary Mining Forum, Apr. 8-9, p. 67-8. poster abstractNorthwest Territories, SaskatchewanLamproite, Sampling - DRAP process
DS200712-0088
2006
Janik, T.Bogdanova, S., Gorbatschev, R., Grad, M., Janik, T., Guterch, A., Kozlovskaya, E., Motuza, G., SkridaiteEUROBRIDGE: new insight into the geodynamic evolution of the East European Craton.Geological Society of London Memoir, No. 32, pp. 599-626.EuropeCraton
DS200712-0483
2007
Janik, T.Janik, T., Kozlovskaya, E., Yliniemi, J.Crust mantle boundary in the central Fennoscandian shield: constraints from wide angle P and S wave velocity models and new results of reflection profiling in FinlandJournal of Geophysical Research, Vol. 112, B4, B04302.Europe, FinlandGeophysics - seismics
DS200912-0334
2009
Janik, T.Janik, T., Kozlovskaya, E., Helikkinen, P., Tliniemi, J.Evidence for preservation of crustal root beneath the Proterozoic Lapland-Kola orogen ( northern Fennoscandian shield) derived from P and S wave models.Journal of Geophysical Research, Vol. 114. B 6, B06308.Europe, Finland, Kola PeninsulaGeophysics - seismics
DS202009-1671
2020
Janik, T.Tiira, T., Janik, T., Skrzynik, T., Komminaho, K., Heinonen, A., Veikkolainen, T., Vakeva, S., Korja, A.Full scale crustal interpretation of Kokkola-Kymi ( KOKKY) seismic profile, Fennoscandian shield.Pure and Applied Geophysics, Vol. 177, 8, pp. 3775-3795. pdfEurope, Finlandgeophysics - seismics

Abstract: The Kokkola-Kymi Deep Seismic Sounding profile crosses the Fennoscandian Shield in northwest-southeast (NW-SE) direction from Bothnian belt to Wiborg rapakivi batholith through Central Finland granitoid complex (CFGC). The 490-km refraction seismic line is perpendicular to the orogenic strike in Central Finland and entirely based on data from quarry blasts and road construction sites in years 2012 and 2013. The campaign resulted in 63 usable seismic record sections. The average perpendicular distance between these and the profile was 14 km. Tomographic velocity models were computed with JIVE3D program. The velocity fields of the tomographic models were used as starting points in the ray tracing modelling. Based on collected seismic sections a layer-cake model was prepared with the ray tracing package SEIS83. Along the profile, upper crust has an average thickness of 22 km average, and P-wave velocities (Vp) of 5.9-6.2 km/s near the surface, increasing downward to 6.25-6.40 km/s. The thickness of middle crust is 14 km below CFGC, 20 km in SE and 25 km in NW, but Vp ranges from 6.6 to 6.9 km/s in all parts. Lower crust has Vp values of 7.35-7.4 km/s and lithospheric mantle 8.2-8.25 km/s. Moho depth is 54 km in NW part, 63 km in the middle and 43 km in SW, yet a 55-km long section in the middle does not reveal an obvious Moho reflection. S-wave velocities vary from 3.4 km/s near the surface to 4.85 km/s in upper mantle, consistently with P-wave velocity variations. Results confirm the previously assumed high-velocity lower crust and depression of Moho in central Finland.
DS1997-0551
1997
Jankovic, S.Jankovic, S.The Carpatho-Balkanides and adjacent area: a sector of the Tethyan Eurasian metallogenic beltMineralium Deposita, Vol. 32, No. 5, pp. 426-433GlobalMetallogeny, genesis, model, Ore deposits, tectonic setting
DS1860-0315
1879
Jannetaz, E.Jannetaz, E.Sur les Colorations de Diamant dans la Lumiere PolariseeSoc. Min. France (paris) Bulletin., Vol. 2, P. 124.GlobalDiamond crystallography
DS1860-0316
1879
Jannetaz, E.Jannetaz, E.Observations sur la Communique de M. ChaperSoc. Min. France (paris) Bulletin., Vol. 2, PP. 200-201.Africa, Africa, South Africa, Griqualand WestDiamond crystallography
DS1860-0385
1882
Jannetaz, E.Jannetaz, E.Analyse D'un Pyroxene Vert des Mines Diamantiferes du CapSoc. Min. France (paris) Bulletin., Vol. 5, P. 281.Africa, South Africa, Cape ProvinceDiamond Mineralogy
DS1860-0469
1885
Jannetaz, E.Jannetaz, E.Note sur Un Diamant du CapSoc. Min. France (paris) Bulletin., Vol. 8, PP. 42-43.Africa, South AfricaDiamond crystallography
DS1860-0367
1881
Jannettaz, E.Jannettaz, E., Fontenay, E., Vanderheym, E., Coutance, A.Diamant et Pierres Precieuses. Cristall. Descript. Emplois, evaluation.Paris:, 580P. SECOND EDITION.GlobalGemology
DS2000-0139
2000
JanneyCarlson, R.W., Janney, Shirey, Boyd, Pearson, IrvineChemical and age structure of the southern African lithospheric mantle: implications continent formationGeological Society of America (GSA) Abstracts, Vol. 32, No. 7, p.A-163.South AfricaMantle xenoliths - Kaapvaal Craton, Geophysics - seismics
DS201012-0321
2010
Janney, P.Janney, P., Bell, D.Pb isotope evidence of a cognate origin for Cr poor megacrysts in southern African kimberlites.Goldschmidt 2010 abstracts, posterAfrica, South AfricaGeochronology
DS201607-1354
2016
Janney, P.Janney, P.A hidden mantle reservoir in the continental lithosphere? Evidence from Hf-Sr-Nd-Pb isotopes in megacrysts and kimberlites.IGC 35th., Session A Dynamic Earth 1p. AbstractMantleKimberlite
DS201607-1381
2016
Janney, P.Tappe, S., Griffin, W., Janney, P., Arndt, N., Gurney, J.The dynamic Earth and its kimberlite, cratonic mantle and diamond record through time.IGC 35th., Session A Dynamic Earth 1p. AbstractMantleKimberlite
DS201708-1680
2017
Janney, P.Janney, P.Hidden reservoirs in the continental lithosphere? Evidence from Hf-Sr-Nd-Pb isotopes in southern African kimberlite megacrysts.11th. International Kimberlite Conference, OralAfrica, Southern Africageochronology
DS201708-1681
2017
Janney, P.Janney, P.Geochemistry of the Namaqualand, Busmanland and Warmbad melillitite and kimberlite provinces of South Africa and Namibia: the southern extension of the African kimberlitic megalineament.11th. International Kimberlite Conference, PosterAfrica, South Africa, Namibiageochemistry, lineament
DS201810-2315
2018
Janney, P.Fitzpayne, A., Giuliani, A., Hergt, J., Phillips, D., Janney, P.New geochemical constraints on the origins of MARID and PIC rocks: implications for mantle metasomatism and mantle -derived potassic magmatism.Lithos, Vol. 318-319, pp. 478-493.Mantlemetasomatism
DS201812-2809
2018
Janney, P.Fitzpayne, A., Giuliani, A., Hergt, J., Phillips, D., Janney, P.New geochemical constraints on the origins of MARID and PIC rocks: implications for mantle metasomatism and mantle derived potassic magmatism. ( kimberlite)Lithos, Vol. 318-319, pp. 478-493.Globallamproites

Abstract: MARID (Mica-Amphibole-Rutile-Ilmenite-Diopside) and PIC (Phlogopite-Ilmenite-Clinopyroxene) rocks are unusual mantle samples entrained by kimberlites and other alkaline volcanic rocks. The formation of MARID rocks remains hotly debated. Although the incompatible element (for example, large ion lithophile element) enrichment in these rocks suggests that they formed by mantle metasomatism, the layered textures of some MARID samples (and MARID veins in composite xenoliths) are more indicative of formation by magmatic processes. MARID lithologies have also been implicated as an important source component in the genesis of intraplate ultramafic potassic magmas (e.g., lamproites, orangeites, ultramafic lamprophyres), due to similarities in their geochemical and isotopic signatures. To determine the origins of MARID and PIC xenoliths and to understand how they relate to alkaline magmatism, this study presents new mineral major and trace element data and bulk-rock reconstructions for 26 MARID and PIC samples from the Kimberley-Barkly West area in South Africa. Similarities between compositions of PIC minerals and corresponding phases in metasomatised mantle peridotites are indicative of PIC formation by pervasive metasomatic alteration of peridotites. MARID genesis remains a complicated issue, with no definitive evidence precluding either the magmatic or metasomatic model. MARID minerals exhibit broad ranges in Mg# (e.g., clinopyroxene Mg# from 82 to 91), which may be indicative of fractionation processes occurring in the MARID-forming fluid/melt. Finally, two quantitative modelling approaches were used to determine the compositions of theoretical melts in equilibrium with MARID rocks. Both models indicate that MARID-derived melts have trace element patterns resembling mantle-derived potassic magma compositions (e.g., lamproites, orangeites, ultramafic lamprophyres), supporting inferences that these magmas may originate from MARID-rich mantle sources.
DS201902-0271
2019
Janney, P.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; eNdi: +3.0 to +3.6; eHfi: +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; eNdi: -11.0 to -1.0; eHfi: -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 (?eHfi 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; eNdi = -11.0; eHfi = -17.9; and 206Pb/204Pbi = 17.3) by the entraining kimberlite magma (87Sr/86Sr; eNd; eHf; 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 ?eHfi values in kimberlites. The isotopic composition of the inferred initial MARID end-member, with high 87Sr/86Sr and low eNd, eHf, 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.
DS201910-2257
2019
Janney, P.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; eNdi: +3.0 to +3.6; eHfi: +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; eNdi: -11.0 to -1.0; eHfi: -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 (?eHfi 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; eNdi = -11.0; eHfi = -17.9; and 206Pb/204Pbi = 17.3) by the entraining kimberlite magma (87Sr/86Sr ~ i 0.704 ; eNd ~ i + 3.3 ; eHf ~ 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 ?eHfi values in kimberlites. The isotopic composition of the inferred initial MARID end-member, with high 87Sr/86Sr and low eNd, eHf, 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.
DS1998-0683
1998
Janney, P.E.Janney, P.E., Le Roex, A.P.Causes of compositional diversity in the olivine melilitites of Namaqualand- Bushmanland.7th International Kimberlite Conference Abstract, pp. 371-3.South AfricaMelilitites, Alkaline diatremes
DS1998-0684
1998
Janney, P.E.Janney, P.E., Le Roex, A.P., Viljoen, K.S.Trace element and isotopic characteristics of olivine melilitites from The western Cape: source for Group I.7th International Kimberlite Conference Abstract, pp. 374-6.South Africa, NamaqualandCape Fold Belt, Melilitites, Group I kimberlites
DS2001-0531
2001
Janney, P.E.Janney, P.E., Castillo, P.R.Geochemistry of the oldest Atlantic oceanic crust suggests mantle plume involvement in early history...Earth and Planetary Science Letters, Vol. 192, No. 3, pp. 291-302.Atlantic OceanMantle plume - not specific to diamonds
DS2002-0764
2002
Janney, P.E.Janney, P.E., LeRoex, A.P., Carlson, R.W., Viljoen, K.S.A chemical and multi isotope study of the western Cape olivine melilitite province SouthJournal of Petrology, Vol. 43, 12, pp. 2339-70.South AfricaGeochemistry - HIMU signature, Geochronology
DS2003-0095
2003
Janney, P.E.Bell, D.R., Schmitz, M.D., Janney, P.E.Mesozoic thermal evolution of the southern African mantle lithosphereLithos, Vol. 71, 2-4, pp. 273-87.South AfricaGeothermometry
DS2003-0646
2003
Janney, P.E.Janney, P.E., Le Roex, A.P., Carlson, R.W., Bell, D.R.Os and Hf isotope constraints on the sources of olivine melilitites from western South8 Ikc Www.venuewest.com/8ikc/program.htm, Session 7, POSTER abstractSouth AfricaGeochronology
DS200412-0130
2003
Janney, P.E.Bell, D.R., Schmitz, M.D., Janney, P.E.Mesozoic thermal evolution of the southern African mantle lithosphere.Lithos, Vol. 71, 2-4, pp. 273-87.Africa, South AfricaGeothermometry
DS200412-0903
2003
Janney, P.E.Janney, P.E., Le Roex, A.P., Carlson, R.W., Bell, D.R.Os and Hf isotope constraints on the sources of olivine melilitites from western South Africa.8 IKC Program, Session 7, POSTER abstractAfrica, South AfricaKimberlite petrogenesis Geochronology
DS200512-0220
2005
Janney, P.E.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
DS201012-0322
2010
Janney, P.E.Janney, P.E., Shirey, S.B., Carlson, R.W., Pearson, D.G., Bell, D.R., Le Roex, A., Ishikawa, Nixon, BoydAge, composition and thermal characteristics of South African off craton mantle lithosphere: evidence for a multi stage history.Journal of Petrology, Vol. 51, 9, pp. 1849-1890,Africa, South AfricaGeochronology, geothermometry
DS201112-0476
2011
Janney, P.E.Janney, P.E., Bell, D.R.Pb Sr Nd Hf isotope variations of megacrysts from Mesozoic Southern African kimberlites reflect mixing of HIMU melts with deep lithosphere.Goldschmidt Conference 2011, abstract p.1102.Africa, South AfricaPofadder, Monastery
DS201412-0173
2014
Janney, P.E.Day, J.M.D., Peters, B.J., Janney, P.E.Oxygen isotope systematics of South African olivine melilitites and implications for HIMU mantle reservoirs.Lithos, Vol. 202-203, pp. 76-84.Africa, South AfricaMelilitite
DS201510-1794
2015
Janney, P.E.Ogungbuyi, P.I., Janney, P.E., Harris, C.The petrogenesis and geochemistry of the Zandkopsdrift carbonatite complex, Namaqualand, South Africa.GSA Annual Meeting, Paper 131-14, 1p. Abstract onlyAfrica, South AfricaCarbonatite

Abstract: Petrologic and geochemical data for carbonatites and associated alkaline igneous rocks are presented for the Zandkopsdrift Carbonatite Complex, Namaqualand. The samples included in this study are relatively fresh, collected by coring at depths of >70 m below the weathered cap zone. The Zandkopsdrift complex is the only locality in the province known to contain significant carbonatite. The carbonatites studied are calico-, ferro- and silico- carbonatites, based on mineralogy, texture, and major element composition. They have low to moderate Mg-numbers (35-65), variable MgO contents (1.2-8.50 wt.%) and high atomic Ca/Ca+Mg (0.73-0.97), indicating that they are not likely simple mantle melts. The carbonatites contain significant apatite, magnetite, pyrochlore and phlogopite. Zandkopsdrift also contains significant amounts of aillikite and olivine melilitite. These rocks have relatively low SiO2 (25-31 wt.%) and Al2O3 (5.3- 6.1 wt.%), high K2O (6-6.3 wt.%) and TiO2 (5.6-9.5 wt.%) and moderate Mg numbers (51-58). d18O and d13C isotopes were measured for carbonatites and aillikites. d13CPDB values are close to those expected for mantle-derived carbonatites (-3.9 to -8.83), while the d18OSMOW values are significantly higher (+13. 25 to 21.84‰). The high d18O value observed in carbonatites and aillikites is most likely attributable to secondary alteration by hydrous/hydrothermal fluids. This supports the inference that the Zandkopsdrift carbonatite is magmatic in origin but was later affected by secondary alteration which resulted in the elevated O stable isotopes. The ‘mantle-like’ d13C is inconsistent with significant assimilation of C-bearing crustal rocks. Chondrite-normalised REE contents in the carbonatites are 2400 to 10,600 for La and 36 to 170 for Lu. The high REE contents of the carbonatites are most likely due to a combination of a source metasomatised by a highly LREE-enriched agent, as well as significant magmatic differentiation. The relatively fractionated composition of the Zandkopsdrift aillikites and melilitites is also consistent with this hypothesis. We propose that the Zandkopsdrift carbonatites were most likely formed by either immiscible liquid separation from or fractional crystallization of a moderately fractionated, carbonate-rich silicate parental magma. Session No. 131--Booth# 338
DS201709-2039
2017
Janney, P.E.Ogungbuyi, P.I., Janney, P.E., Harris, C.The geochemistry and genesis of Marinkas Quellen carbonatite complex, southwestern Namibia.Goldschmidt Conference, abstract 1p.Africa, Namibiacarbonatite

Abstract: The 525 Ma Marinkas Quellen (MQ) Complex of southern Namibia, part of the Kuboos-Bremen Line (KBL) of alkaline igneous centers [1] consists of granites, nepheline syenites and carbonatites and is the only carbonatite locality in the KBL [1]. MQ carbonatite variteties include calciocarbonatites, magnesiocarbonatites and ferrocarbonatites. The enrichments in Ba, Nb and the REE vary widely in the carbonatites, with La ranging from 45 to 11154 ppm. All the carbonatites are characterised by large Zr, Hf, Ti depletions. Zr/Hf ratios ranges from 40 to 500, all greater than the chondritic value of 36. Such large Zr/Hf fractionations are often associated with carbonatite metasomatism. The values of carbon and oxygen isotope ratios of bulk carbonate in Marinkas Quellen carbonatites vary significantly (e.g., d13C = -3.95 to -6.02‰; d18 O = 8.84 to 22.22‰). The carbon isotope compositions are in the mantle range, while the oxygen isotope values extend to higher than typical mantle values, presumably due to interaction with hydrous fluids. All but two of the carbonatite samples have initial 87Sr/86Sr ratios falling in the range of 0.70236 to 0.70408. Of the remaining samples, one, a ferrocarbonatite, has a higher value of 0.70503 that is likely due to contamination by the surrounding rock or assimilation in the lower crust or Sr exchange with groundwater. The other, a magnesiocarbonatite, appears to have experienced an increase in its Rb/Sr ratio due to alteration, resulting in an over-corrected initial 87Sr/86Sr value. The relatively low Sr isotope ratios of most samples, plus their HNd(t) values (+3.9 to +4.8) values suggest that the carbonatite magma was generated from a long-lived low Rb/Sr, high Sm/Nd, relatively depleted mantle source. The radiogenic Pb isotope composition of the carbonatites (206Pb/204Pbi ratios from 18.06 to 22.38), suggests a high U/Pb source, akin to the HIMU mantle end member. This points to a sub-lithospheric (asthenospheric) source with only a relatively minor contribution from enriched lithospheric mantle
DS201912-2810
2019
Janney, P.E.Pearson, D.G., Woodhead, J.D., Janney, P.E.Kimberlites as geochemical probes of Earth's mantle.Elements, Vol. 15, 6, pp.Mantlegeochemistry

Abstract: Kimberlites are ultrabasic, Si-undersaturated, low Al, low Na rocks rich in CO2 and H2O. The distinctive geochemical character of kimberlite is strongly influenced by the nature of the local underlying lithospheric mantle. Despite this, incompatible trace element ratios and radiogenic isotope characteristics of kimberlites, filtered for the effects of crustal contamination and alteration, closely resemble rocks derived from the deeper, more primitive, convecting mantle. This suggests that the ultimate magma source is sub-lithospheric. Although the composition of primitive kimberlite melt remains unresolved, kimberlites are likely derived from the convecting mantle, with possible source regions ranging from just below the lithosphere, through the transition zone, to the core-mantle boundary.
DS202107-1118
2021
Janney, P.E.Nkere, B.J., Janney, P.E., Tinguely, C.Cr-poor and Cr-rich clinopyroxene and garnet megacrysts from southern African Group 1 and Group 2 kimberlites: clues to megacrysts origins and their relationship to kimberlites.Lithos, Vol. 396-397, 106231 pdfAfrica, South Africa, Botswanadeposit - Colossus, Orapa, Kalput, Bellsbank

Abstract: Controversies surroun