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SDLRC - Scientific Articles all years by Author - O


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 - O
Posted/
Published
AuthorTitleSourceRegionKeywords
DS201905-1059
2019
OMortet, V., Vickova Zicova, Z., Taylor, A., Davydova, M., Frank, O,m Hubik, P., Lorincik, J., Aleshin, M.Determination of atomic boron concentration in heavily boron-doped diamond by Raman spectroscopy.Diamond & Related Materials, Vol. 93, pp. 54-58.Globalspectroscopy

Abstract: Raman spectroscopy has been foreseen as a simple and non-destructive characterization method to determine the boron concentration in heavily boron-doped diamond with metallic conductivity. However, currently available empirical studies are not fully satisfactory for enabling accurate determination of the boron concentration in diamond. Here, we study Raman spectra of epitaxial boron-doped diamond as a function of the boron concentration and the excitation wavelength. The zone center phonon and the phonon density of state maximum (at ca. 1200?cm-1) lines are analyzed using a decoupled double Fano-function. This analysis method accurately describes the observed variation of the asymmetric parameters with atomic boron concentration and the photon excitation energy and enables the determination of the atomic boron concentration from the parameters of the examined Raman lines.
DS200612-0111
2006
O Connell, R.J.Becker, T.W., Sculte Pelkum, V., Blackman, D.K., Kellogg, J.B., O Connell, R.J.Mantle flow under the western United States from shear wave splitting.Earth and Planetary Science Letters, Vol. 247, 3-4, pp. 235-251.United StatesGeodynamics
DS200512-0369
2005
O Reilly, S.Y.Griffin, W.L., Natapov, L.M., O Reilly, S.Y., Van Acterbergh, E., Cherenkova, A.F., Cherenkov, V.G.The Kharamai kimberlite field, Siberia: modification of the lithospheric mantle by the Siberian Trap event.Lithos, Vol. 81, 1-4, pp. 167-187.Russia, SiberiaMetasomatism
DS200512-1259
2005
O Reilly, S.Y.Zheng, J., Griffin, W.L., O Reilly, S.Y., Liou, J.G., Zhang, R.Y., Lu, F.Late Mesozoic Eocene mantle replacement beneath the eastern North Chin a Craton: evidence from the Paleozoic and Cenozoic peridotite xenoliths.International Geology Review, Vol. 47, 5, May, pp. 457-472.ChinaXenoliths
DS1996-1089
1996
O.Reilly, S.Y.Pearson, N.J., O.Reilly, S.Y., Griffin, W.L.Lower crust geothermsInternational Geological Congress 30th Session Beijing, Abstracts, Vol. 1, p. 119.South AfricaKaapvaal Craton, Geothermometry
DS200412-1090
2004
Oa-bttat, M.A.O.Le Bas, M.J., Oa-bttat, M.A.O., Taylor, R.N., Milton, J.A., Windley, B.F., Evins, P.M.The carbonatite marble dykes of Abyan Province, Yemen Republic: the mixing of mantle and crustal carbonate materials revealed byMineralogy and Petrology, Vol. 82, 1-2, pp. 105- DOI 10.1007/ s00710-004-0056-2YemenCarbonatite, geochronology
DS1983-0410
1983
Oakes, G.M.Lishmund, S.R., Oakes, G.M.Diamonds, Sapphires and Cretaceous Tertiary Diatremes in New South Wales.New South Wales Geological Survey Quarterly Notes, No. 53, OCTOBER PP. 23-27.Australia, New South WalesProspecting
DS1984-0456
1984
Oakes, G.M.Lishmund, S.R., Oakes, G.M.Sapphires and diamonds in New South Wales; are Tertiary diatremes and relatedpyroclastics the answer?In: Geoscience in the development of Natural Resources Abstract Volume, Vol. 12, pp. 334-336AustraliaBlank
DS1984-0457
1984
Oakes, G.M.Lishmund, S.R., Oakes, G.M.Sapphires and Diamonds in New South Wales- are Tertiary Diatremes and Related Pyroclastics the Answer?Geological Society of Australia ABSTRACT VOLUME., No. 12, PP. 334-336. EXTENDED ABSTRACT.Australia, New South WalesGenesis, Invernell
DS1994-0112
1994
Oakes, G.M.Barron, L.M., Lishmund, S.R., Oakes, G.M., Barron, B.J.Subduction diamonds in New South Wales: implications for exploration In eastern Australia.Quart. Notes Geological Society New South Wales, pp. 1-23.AustraliaSubduction, ES-diamond model
DS1994-0113
1994
Oakes, G.M.Barron, L.M., Lishmund, S.R., Oakes, G.M., Barron, B.J.A new model for the origin of some diamonds in eastern AustraliaGeological Society of Australia Abstracts, No. 37, pp. 19, 20.Australia, New South Wales, VictoriaDiamond genesis
DS1998-0083
1998
Oakes, G.M.Barron, L.M., Lishmund, S.R., Oakes, G.M., Barron, B.J.Primary and related diamond occurrences within a Phanerozoic subduction regime eastern New South Wales7th International Kimberlite Conference Abstract, pp. 46-48.Australia, New South WalesSubduction, Diamond model
DS2000-0061
2000
Oakes, G.M.Barron, L.M., Lishmund, S.R., Barron, B.J., Oakes, G.M.Features of diamonds from Copeton Bingara NSW AustraliaGeological Society of Australia 15th Geological Convention, 1p. abstractAustralia, New South WalesBlank
DS2003-0076
2003
Oakes, G.M.Barron, L.M., Lishmund, S.R., Barron, B.J., Oakes, G.M.Features of diamonds from Copeton, NSW. AustraliaPreprint from author, 13p.Australia, New South WalesDeposit - Copeton, Bingara
DS200412-0103
2000
Oakes, G.M.Barron, L.M., Lishmund, S.R., Barron, B.J., Oakes, G.M.Features of diamonds from Copeton Bingara NSW Australia.Geological Society of Australia 15th Geological Convention, 1p. abstractAustralia, New South WalesDiamond - morphology
DS200412-0104
2003
Oakes, G.M.Barron, L.M., Lishmund, S.R., Barron, B.J., Oakes, G.M.Features of diamonds from Copeton, NSW. Australia.Preprint from author, 13p.Australia, New South WalesAlkali basalt, basanite, leucitite Deposit - Copeton, Bingara
DS1999-0519
1999
Oakey, G.N.Oakey, G.N., et al.Circum-Arctic magnetic map with tectonic overlay, polar stereographprojection.Geological Survey of Canada (GSC), Open file 3691, 1:6, 000, 000 $ 20.00Northwest Territories, ArcticGeophysics - magnetics
DS201212-0525
2012
Oakey, G.N.Oakey, G.N., Chalmers, J.A. A new model for the Paleogene motion of Greenland relative to North America: plate reconstructions of the Davis Strait and Nares Strait regions between Canada and Greenland.Journal of Geophysical Research, Vol. 117, B 10, B10401.Canada, Europe, GreenlandTectonics
DS1992-1619
1992
Oarsons, I.Waldron, K.A., Oarsons, I.Feldspar microtextures and multistage thermal history of syenites from the Coldwell Complex, OntarioContributions to Mineralogy and Petrology, Vol. 111, No. 2, July pp. 222-234OntarioColdwell Complex, Alkaline rocks
DS1940-0134
1946
Oates, F.Teale, E.O., Oates, F.The Mineral Resources of Tanganyika TerritoryGeological Survey TANGANYIKA Bulletin., No. 16. 171P.Tanzania, East AfricaMineral Resources, Diamond
DS1860-0419
1883
Oats, F.Oats, F.On Dunn's Notes on the Diamond Fields of South AfricaQuarterly Journal of Geological Society (London), Vol. 39, P. 5. ALSO: Geology Magazine (London), Dec. 2, Vol. 10, PAfrica, South Africa, Cape ProvinceGeology
DS200912-0237
2009
Oba, M.Furukawa, Y., Sekine, T., Oba, M., Kakegawa, T., Nakazawa, H.Biomolecule formation by oceanic impacts on early Earth. ( subducting .. conversion to graphite or diamond....)Nature Geoscience, Vol. 2, no. 1, pp. 62-66.MantleSubduction
DS201705-0866
2017
Obale, O.Obale, O.From conflict to illicit.pacweb.org, 36 pdf.Africa, Cameroon, Central African RepublicDiamond industry
DS200612-0994
2006
Oban, H.Oban, H., Flower, M.F.Mineral phase compositions in silica undersaturated leucite lamproites from the Bucak area, I sparta SW Turkey.Lithos, Vol. 89, 3-4, pp. 275-299.Europe, TurkeyLamproite
DS201808-1790
2017
Obannon, E.F.Stan, C.V., Obannon, E.F., Dobrzhinetskaya, L.F., Tamura, N.Polytypism in natural SiC using Laue microdiffraction.Acta Crystallographia, A70, 1p. abstractEurope, Israelmoissanite

Abstract: Silicon carbide (SiC, moissanite) is a common industrial material that is rarely found in terrestrial rocks and meteorites. It has been found to adopt over 300 different crystal structures, most of which are polytypic: they consist of alternating layers of Si and C, with only small stacking faults or shears distinguishing them from one another. In nature, only a few polytypes of SiC have been found, primarily a cubic zincblende type (3C-SiC), several hexagonal wurtzite types (4H-SiC and 6H-SiC), and a rhombohedral type (15R-SiC). Our natural silicon carbide sample is from a Miocene tuff (Yizre’el Valley, Israel) related to interplate alkaline basalt volcanism. Three SiC grains with native silicon and metal silicide inclusions were analyzed using Raman spectroscopy and synchrotron Laue X-ray microdiffraction accompanied by mapping at a 5-8 um resolution. SiC is found to crystallize in only the 4H and 6H polytypes. Due to the crystal orientation of the grains, as well as the significant difference in the c-axis length (~10 vs. ~15 um in 4H and 6H respectively), we were able to unambiguously assign polytypes to each diffraction pattern. Each grain contains large areas where one polytype dominates as a single crystal. In some cases, multiple stacking faults and misoriented polycrystalline aggregates of SiC occur at the 4H/6H interface. In other cases we see intercalation of the 4H and 6H crystals throughout the diffracting volume without a significant change in their crystallographic axes orientation, pointing to a possibly incommensurate crystal structure. Stress and strain are also mapped for all three grains, showing a slight (< 2 ppt) compressive strain in the y direction of all three grains, and a tensile strain in the x and z directions. In the SiC-2 grain, a mostly single-crystalline Si inclusion was found, with an exposed surface diameter of ~30 um. We examine residual strain in Si by both Laue X-ray diffraction and Raman spectroscopy, and find results to generally agree between the two measurements.
DS201212-0163
2013
O'Bannon, E.Dobrzhinetskaya, L.F., Wirth, R., Green, H.W., Schreiber, A., O'Bannon, E.First find of polycrystalline diamond in ultrahigh-pressure metamorphic terrane of Erzgebirge, Germany.Journal of Metamorphic Geology, Vol. 31, 1, pp. 5-18.Europe, GermanyUHP
DS201212-0164
2012
O'bannon, E.Dobrzhinskaya, L.F., Wirth, R., Green, H.W., Schreiber, A., O'bannon, E.First find of polycrystalline diamond in ultrahigh pressure metamorphic terrane of Erzgebirge Germany.Journal of Metamorphic Geology, in press availableEurope, GermanyUHP
DS201312-0219
2013
O'Bannon, E.Dobrzhinetskaya, L., Wirth, R., Green, H.W., Schreiber, A., O'Bannon, E.First find of polycrystalline diamond in ultrahigh pressure metamorphic terrane of Erzgebirge Germany.Journal of Metamorphic Geology, Vol. 31, pp. 5-18.Europe, GermanyUHP
DS201805-0943
2018
O'Bannon, E.Dobrzhinetskaya, L., Mukhin, P., wang, Q., Wirth, R., O'Bannon, E., Zhao, W., Eppelbaum, L., Sokhonchuk, T.Moissanite ( SiC) with metal silicide and silicon inclusions from tuff of Israel: raman spectroscopy and electron microscope studies.Lithos, in press available 58p.Europe, Israelmoissanite

Abstract: Here, we present studies of natural SiC that occurs in situ in tuff related to the Miocene alkaline basalt formation deposited in northern part of Israel. Raman spectroscopy, SEM and FIB-assisted TEM studies revealed that SiC is primarily hexagonal polytypes 4H-SiC and 6H-SiC, and that the 4H-SiC polytype is the predominant phase. Both SiC polytypes contain crystalline inclusions of silicon (Sio) and inclusions of metal-silicide with varying compositions (e.g. Si58V25Ti12Cr3Fe2, Si41Fe24Ti20Ni7V5Zr3, and Si43Fe40Ni17). The silicides crystal structure parameters match Si2TiV5 (Pm-3 m space group, cubic), FeSi2Ti (Pbam space group, orthorhombic), and FeSi2 (Cmca space group, orthorhombic) respectively. We hypothesize that SiC was formed in a local ultra-reduced environment at respectively shallow depths (60-100 km), through a "desilification" reaction of SiO2 with highly reducing fluids (H2O-CH4-H2-C2H6) arisen from the mantle "hot spot" and passing through alkaline basalt magma reservoir. SiO2 (melt) interacting with the fluids may originate from the walls of the crustal rocks surrounding this magmatic reservoir. The "desilification" process led to the formation of SiC and the reduction of metal-oxides to native metals, alloys, and silicides. The latter were trapped by SiC during its growth. Hence, interplate "hot spot" alkali basalt volcanism can now be included as a geological environment where SiC, silicon, and silicides can be found.
DS202006-0944
2020
O'Bannon, E.O'Bannon, E., Xia, G., Shi, F., Wirth, R., King, R.A., Dobrzhinetskaya, L.The transformation of diamond to graphite: experiments reveal the presence of an intermediate linear carbon phase. Diamonds & Related Materials, in press available, 31p. PdfGlobalcarbon

Abstract: Natural diamonds that have been partially replaced by graphite have been observed to occur in natural rocks. While the graphite-to-diamond phase transition has been extensively studied the opposite of this (diamond to graphite) remains poorly understood. We performed high-pressure and temperature hydrous and anhydrous experiments up to 1.0?GPa and 1300?°C using Amplex premium virgin synthetic diamonds (20-40?µm size) as the starting material mixed with Mg (OH)2 as a source of H2O for the hydrous experiments. The experiments revealed that the diamond-to-graphite transformation at P?=?1GPa and T?=?1300?°C was triggered by the presence of H2O and was accomplished through a three-stage process. Stage 1: diamond reacts with a supercritical H2O producing an intermediate 200-500?nm size “globular carbon” phase. This phase is a linear carbon chain; i.e. a polyyne or carbyne. Stage 2: the linear carbon chains are unstable and highly reactive, and they decompose by zigzagging and cross-linking to form sp2-bonded structures. Stage 3: normal, disordered, and onion-like graphite is produced by the decomposition of the sp-hybridized carbon chains which are re-organized into sp2 bonds. Our experiments show that there is no direct transformation from sp3 C-bonds into sp2 C-bonds. Our hydrous high-pressure and high-temperature experiments show that the diamond-to-graphite transformation requires an intermediate metastable phase of a linear hydrocarbon. This process provides a simple mechanism for the substitution of other elements into the graphite structure (e.g. H, S, O).
DS201808-1766
2018
O'Bannon, E.F.Machev, P., O'Bannon, E.F., Bozhilov, K.N., Wang, Q., Dobrzhinetskaya, L.Not all moissanites are created equal: new constraints on moissanite from metamorphic rocks of Bulgaria. Earth and Planetary Science Letters, Vol. 498, pp. 387-396.Europe, Bulgariamoissanite

Abstract: Terrestrial moissanite (SiC) is widely reported as an ultra-high pressure mineral occurring in kimberlites, diamonds and ultramafic/mafic rocks of mantle origin. However, the conditions of crystallization remain largely unknown. Moreover, dozens of SiC occurrences have been reported from continental crust sources such as granitoids, andesite-dacite volcanic rocks and their breccia, metasomatic and metamorphic rocks, and even limestones. The validity of many of these reports is still debated primarily due to possible contaminations from the widespread use of synthetic SiC abrasives in samples preparation. Indeed, reports of well-documented in-situ occurrences of moissanite in association with co-existing minerals are still scarce. The only condition of moissanite formation that is agreed upon is that extremely reducing media are required (e.g. 4.5-6 log units below the iron-wustite buffer). Here, we report the new occurrence of moissanite that was found in-situ within the garnet-staurolite-mica schists of Topolovgrad metamorphic group of Triassic age in Southern Bulgaria. The 10-300 µm moissanite crystals are situated within 0.1-1.2 mm isolated clusters, filled with amorphous carbon and nanocrystalline graphite. Most of moissanite crystals are 15R (rhombohedral) and 6H (hexagonal) polytypes, and one prismatic crystal, found within them, exhibits unusual concentric polytypical zoning with core (15R), intermediate zone (6H) and rim (3C-cubic). Experimental data show that this type of polytypical zonation is likely due to a decrease in temperature (or/and pressure?) and changes in Si/C ratio. Indeed, amphibolite facies metamorphism (500-580?°C - garnet-staurolite zone) followed by a subsequent cooling during the retrograde stage of green schist facies metamorphism (~400-500?°C) could have provided a change in temperature. The SiC containing clusters exhibit evidence that they are pre-metamorphic, and we hypothesize that their protolith was a "lack shale" material likely rich in carbon, hydrocarbon and terrigenous silica. The latter served as a source of isolated chemically-reduced media, which is required for SiC formation. Other concepts to explain moissanite occurrences in metasedimentary rocks are also discussed. Importantly, our findings show that the formation conditions of moissanite are likely more variable than previously recognized.
DS202004-0535
2020
O'Bannon III, E.F.Stan, C.V., O'Bannon III, E.F., Mukhin, P., Tamura, N., Dobrzhinetskaya, L.X-ray laue microdiffraction and raman spectroscopic investigation of natural silicon and moissanite.Minerals MDPI, Vol. 10, 10030204 12p. PdfGlobalmoissanite

Abstract: Moissanite, SiC, is an uncommon accessory mineral that forms under low oxygen fugacity. Here, we analyze natural SiC from a Miocene tuff-sandstone using synchrotron Laue microdiffraction and Raman spectroscopy, in order to better understand the SiC phases and formation physics. The studied crystals of SiC consist of 4H- and 6H-SiC domains, formed from either, continuous growth or, in one case, intergrown, together with native Si. The native Si is polycrystalline, with a large crystal size relative to the analytical beam dimensions (>1-2 µm). We find that the intergrown region shows low distortion or dislocation density in SiC, but these features are comparatively high in Si. The distortion/deformation observed in Si may have been caused by a mismatch in the coefficients of thermal expansion of the two materials. Raman spectroscopic measurements are discussed in combination with our Laue microdiffraction results. Our results suggest that these SiC grains likely grew from an igneous melt.
DS1975-0369
1976
Obata, M.Obata, M.The Solubility of Al2o3 in Orthopyroxenes in Spinel and Plagioclase Peridotites and Spinel Pyroxenite.American MINERALOGIST., Vol. 61, PP. 804-816.GlobalPyrope, Model
DS1983-0474
1983
Obata, M.Nagata, J., Goto, A., Obata, M.The Parabolic Pattern of Chromium Partioning Observed Between Pyroxenes and Spinel from Ultramafic Rocks and its Petrologic Significance.Contributions to Mineralogy and Petrology, Vol. 82, No. 1, PP. 42-51.GlobalMineral Chemistry, Mineralogy
DS1987-0541
1987
Obata, M.Obata, M., Morten, L.Transformation of spinel lherzolite to garnet lherzolite in ultramafic lenses of the Austridic crystalline complex,northern ItalyJournal of Petrology, Vol. 28, pt. 3, pp. 599-623ItalyGarnet lherzolite, Garnet Peridotite
DS1987-0542
1987
Obata, M.Obata, M., Nagahara, N.Layering of alpine type peridotite and the segregation of partial melt In the upper mantleJournal of Geophysical Research, Vol. 92, No. b5 April 10, pp. 3467-3474JapanMantle genesis, Metasomatism
DS1992-1513
1992
Obata, M.Takazawa, E., Frey, F.A., Shimizu, N., Obata, M.Geochemical evidence for melt migration and reaction in the upper mantleNature, Vol. 359, No. 6390, September 3, pp. 55-58MantleMelt, Geochemistry
DS1993-0320
1993
Obata, M.Davies, G.R., Nixon, P.H., Pearson, D.G., Obata, M.Tectonic implications of graphitized diamonds from the Ronda peridotitemassif, southern SpainGeology, Vol. 21, No. 5, May pp. 471-474GlobalTectonics, Graphite morphology, Pyroxene
DS1994-0387
1994
Obata, M.Davies, G.R., Nixon, P.H., Pearson, G., Obata, M.Octahedral graphite bearing pyroxenites from Ronda, S. SpainProceedings of Fifth International Kimberlite Conference, Vol. 1, pp. 318-326.GlobalPyroxenites, Ronda
DS1994-1292
1994
Obata, M.Obata, M.Material transfer and local equilibration temperatures in a zoned kelphite from a garnetpyroxenite, Ronda Spain.Journal of Petrology, Vol. 35, No. 1, pp. 271-287.GlobalPyroxenite, Garnet - rims
DS1995-1304
1995
Obata, M.Morishita, R., Obata, M.A new statistical description of the spatial distribution of minerals inrocksJournal of Geology, Vol. 103, No. 2, March pp. 232-240GlobalRock textures, Statistics
DS201012-0545
2010
Obata, M.Obata, M.Kelphyite and symplectite after garnet: the microstructure, formation processes and reaction kinetics.International Mineralogical Association meeting August Budapest, AbstractTechnologyRim mineralogy
DS201112-0749
2011
Obata, M.Obata, M., Ozawa, K.Topotaxic relationships between spinel and pyroxene in kelphite after garnet in mantle derived peridotites and their implications to reaction mechanism and kinetics.Mineralogy and Petrology, Vol. 101, 3-4, pp. 217-224.MantleKelphite
DS201312-0660
2013
Obata, M.Obata, M., Ozawa, K., Naemura, K., Miyake, A.Isochemical breakdown of garnet in orogenic garnet peridotite and its implication to reaction kinetics.Mineralogy and Petrology, Vol. 107, 6, pp. 881-895.Europe, Czech RepublicKelphite
DS2001-0345
2001
Obayahi, M.Fukao, Y., Widiyantoro, S., Obayahi, M.Stagnant slabs in the upper and lower mantle transition regionReviews of Geophysics, Vol. 39, No. 3, Aug. pp. 291-324.MantleSlabs, Melting, subduction
DS1992-0495
1992
Obayashi, M.Fukao, Y., Obayashi, M., Inoue, H., Nenbai, M.Subducting slabs stagnant in the mantle transition zoneJournal of Geophysical Research, Vol. 97, No. B 4, April 10, pp. 4809-4822MantleModel transition zone, Subduction -slabs
DS1994-0556
1994
Obayashi, M.Fukao, Y., Maruyama, S., Obayashi, M., Inoue, H.Geologic implication of the whole mantle P wave tomographyJournal of the Geological Society of Japan, Vol. 100, No. 1, January pp. 4-23MantleTomography, Geophysics -seismics
DS1994-0557
1994
Obayashi, M.Fukao, Y., Maruyama, S., Obayashi, M., Inoue, H.Geologic implication of the whole mantle P wave tomographyJournal of the Geological Society of Japan, Vol. 100, No. 1, January pp. 4-23.MantleTomography, Geophysics -seismics
DS200412-0591
2004
Obayashi, M.Fukao, Y., Koyama, T., Obayashi, M., Utada, H.Trans Pacific temperature field in the mantle transition region derived from seismic and electromagnetic tomography.Earth and Planetary Science Letters, Vol. 217, 3-4, Jan. 15, pp.425-434.MantleGeophysics - seismics
DS200612-0617
2006
Obayashi, M.Ichiki, M., Baba, K., Obayashi, M., Utada, H.Water content and geotherm in the upper mantle above the stagnant slab: interpreation of electrical conductivity and seismic P wave velocity models.Physics of the Earth and Planetary Interiors, Vol. 155, 1-2, April 14, pp. 1-15.MantleGeothermometry, harzburgite, back arc volcanism
DS200612-0995
2006
Obayashi, M.Obayashi, M., Sugioka, H., Yoshimitsu, J., Fukao, Y.High temperature anomalies oceanward of subducting slabs at the 410 km discontinuity.Earth and Planetary Science Letters, Vol. 243, 1-2, Mar 15, pp. 149-158.MantleSubduction
DS200912-0234
2009
Obayashi, M.Fukao, Y., Obayashi, M., Nakakuki, T.Stagnant slab: a review.Annual Review of Earth and Planetary Sciences, Vol. 37, pp. 19-46.MantleSubduction
DS200912-0543
2009
Obayashi, M.Obayashi, M., Yoshimitsu, J., Fukao, Y.Tearing of stagnant slab.Science, Vol. 324, 5931, pp. 1173-1175.JapanSubduction
DS200912-0782
2009
Obayashi, M.Utada, H., Koyama, T., Obayashi, M., Fukao, Y.A joint interpretation of electromagnetic and seismic tomography models suggest the mantle transition zone below Europe is dry.Earth and Planetary Science Letters, Vol. 281, 3-4, May 15, pp. 249-257.EuropeGeophysics - seismics
DS201412-0257
2013
Obayashi, M.Fukao, Y., Obayashi, M.Subducted slabs stagnant above, penetrating through, and trapped below the 660 km discontinuity.Journal of Geophysical Research, Vol. 118, 11, pp. 5920-5938.MantleSubduction
DS201412-0644
2013
Obayashi, M.Obayashi, M., Yoshimitsu, J., Noelt, G., Fukao, Y., Shiobara, H., Sugioka, H., Miyamachi, H., Gao, Y.Finite frequency whole mantle P wave tomography: improvement of subducted slab images.Geophysical Research Letters, Vol. 40, 21, pp. 5652-5657.MantleTomography
DS1995-0062
1995
Obei, J.D.Aseno, J.O., Obei, J.D.Deformation monitoring of the Kenyan rift system using linearmeasurements.Geological Society Africa 10th. Conference Oct. Nairobi, pp. 138. Abstract.KenyaTectonics, Geophysics -seismics
DS1993-1151
1993
Oberbeck, V.R.Oberbeck, V.R., Marshall, J.R., Aggarwal, H.Impacts, tillites and the breakup of GondwanalandJournal of Geology, Vol. 101, No. 1, January, pp. 1-19Craters, Rifting
DS1993-1152
1993
Oberbeck, V.R.Oberbeck, V.R., Marshall, J.R., Aggarwal, H.Impacts, tillites and the breakup of GondwanalandJournal of Geology, Vol. 101, No. 1, January pp. 1-19.Tectonics, Rifting
DS2003-0487
2003
Oberg, S.Goss, J.P., Coomer, B.J., Jones, R., Fall, C.J., Briddon, P.R., Oberg, S.Extended defects in diamond: the interstitial plateletPhysical Review, Vol. 67, 16, 15p.GlobalBlank
DS200412-0700
2003
Oberg, S.Goss, J.P., Coomer, B.J., Jones, R., Fall, C.J., Briddon, P.R., Oberg, S.Extended defects in diamond: the interstitial platelet.Physical Review Letters, Vol. 67, 16, 15p.TechnologyDiamond - morphology
DS200612-0082
2006
Oberg, S.Bangert, U., Barnes, R., Hounsome, L.S., Jones, R., Blumenau, A.T., Briddon, P.R., Shaw, M.J., Oberg, S.Electron energy loss spectroscopic studies of brown diamonds.Philosophical Magazine, Vol. 86, no. 29/31, pp. 4757-4780.TechnologyBrown diamonds
DS200612-0604
2006
Oberg, S.Hounsome, L.S., Jones, R., Martineau, P.M., Fisher, D., Shaw, M.J., Briddon, P.R., Oberg, S.Origin of brown coloration in diamond.Physical Review Letters, Vol. 73, 12, pp. 125203 ( 8 pages)TechnologyDiamond - colour
DS200712-0051
2006
Oberg, S.Bangert, U., Barnes, R., Hounsome, L.S., Jones, R., Bhumenau, A.T., Briddon, P.R., Shaw, M.J., Oberg, S.Electron energy loss spectroscopic studies of brown diamonds.Philosophical Magazine, Vol. 86, no. 29-31, pp. 4757-4779.TechnologyType IIa diamonds
DS2001-0331
2001
OberhansliFranz, L., Romer, Klemd, Schmid, Oberhansli, WagnerEclogite facies quartz veins within metabasites of the Dabie Shan: P T time deformation path... fluid phase..Contributions to Mineralogy and Petrology, Vol. 141, No. 3, June, pp. 322-46.Chinaultra high pressure (UHP) - fluid flow, melting, exhumation
DS2002-1168
2002
Oberhansli, R.Oberhansli, R., Matinotti, G., Schmid, R., Liu, X.Preservation of primary volcanic textures in the ultrahigh pressure terrain of Dabie ShanGeology, Vol.30,8,Aug.pp.699-702.ChinaUHP, Deposit - Dabie Shan area
DS2003-1185
2003
Oberhansli, R.Romer, R.L., Wawrzenitz, N., Oberhansli, R.Anomalous unradiogenic 87 Sr 86 Sr ratios in ultrahigh pressure crustal carbonates -Terra Nova, Vol. 15, pp. 330-36.ChinaUHP, subduction, Dabie Shan
DS2003-1225
2003
Oberhansli, R.Schmid, R., Romer, R.L., Franz, L., Oberhansli, R., Martinotti, G.Basement cover sequences within the UHP unit of the Dabie ShanJournal of Metamorphic Geology, Vol. 21, 6, pp. 531-38.ChinaUHP
DS200412-1689
2003
Oberhansli, R.Romer, R.L., Wawrzenitz, N., Oberhansli, R.Anomalous unradiogenic 87 Sr 86 Sr ratios in ultrahigh pressure crustal carbonates - evidence for fluid infiltration during deepTerra Nova, Vol. 15, pp. 330-36.ChinaUHP, subduction, Dabie Shan
DS200412-1755
2003
Oberhansli, R.Schmid, R., Romer, R.L., Franz, L., Oberhansli, R., Martinotti, G.Basement cover sequences within the UHP unit of the Dabie Shan.Journal of Metamorphic Geology, Vol. 21, 6, pp. 531-38.ChinaUHP
DS200612-1512
2006
Oberhansli, R.Wawrzenitz, N., Romer, R.L., Oberhansli, R., Dong, S.Dating of subduction and differential exhumation of UHP rocks fromn the Central Dabie Complex ( E-China): constraints from microfabrics, Rb-Sr and U-Pb isotope systems.Lithos, in press,ChinaGeochronology, UHP
DS1940-0099
1945
Oberholster, J.J.Oberholster, J.J.Die Anneksasie Van Griekwaland WesArchives Year Book, No. 8, 337P.South AfricaMining Laws, Maps
DS1998-1519
1998
Oberli, F.Vance, D., Meier, M., Oberli, F.The influence of high uranium-thorium (U-Th) inclusions on the uranium-thorium-lead systematics of almandine pyrope garnet: resultsGeochimica et Cosmochimica Acta, Vol. 62, No. 21-22, pp. 3527-40.IndiaGarnet mineralogy - not specific to diamonds
DS200812-0699
2008
Oberli, F.Magna, T., Ionov, D.A., Oberli, F., Wiechert, U.Links between mantle metasomatism and lithium isotopes: evidence from glass bearing and cryptically metasomatized xenoliths from Mongolia.Earth and Planetary Science Letters, Vol. 276, 1-2, Nov. pp. 214-222.Asia, MongoliaMetasomatism
DS1997-0860
1997
Obermeyer, N.J.Obermeyer, N.J., Pinto, J.K.Managing Geographic Information SystemsEarth Observation Magazine books, $ 40.00GlobalBook - ad, GIS
DS1940-0034
1941
Obermuller, A.Obermuller, A.Description Petrologie et Geologie de la Region Forestiere De Guinee.Dakar., Bulletin. No. 5West Africa, GuineaGeology, Regional
DS1940-0128
1946
Obermuller, A.Roques, M., Obermuller, A.Discordance de la Serie Antecambrienne du Simandou sur Les Gneiss de Guinee.|Academy of Science COMPTES RENDUS, Vol. 223, No. 26, Dec. 26TH.West Africa, GuineaStratigraphy
DS2002-1169
2002
Oberthur, T.Oberthur, T., Davis, D.W., Blenkinsop, T., Hohdorf, A.Precise U Pb mineral ages, Rb Sr and Sm Nd systematics for the Great Dyke, constraints on late Archean eventsPrecambrian Research, Vol. 113, No. 3-4, pp. 293-305.ZimbabweGeochronology, Craton, uranium, lead, rubidium, strontium, Limpopo Belt
DS1991-1246
1991
Oberti, R.Oberti, R., Capotusco, F.A.Crystal chemistry of clinopyroxenes from mantle eclogites: a study of the key role of the M2 site population by means of crystal structure refinementAmerican Mineralogist, Vol. 76, pp. 1141-1152South AfricaMineral chemistry, Eclogites, Roberts Victor, Bobbejaan
DS1995-1370
1995
Oberti, R.Oberti, R., Hawthorne, F.C., Ungaretti, CannilloAluminum disorder in amphiboles from mantle peridotitesCanadian Mineralogist, Vol. 33, No. 4, August pp. 867-878.MantlePeridotites
DS2003-1380
2003
Oberti, R.Tiepolo, M., Zanetti, A., Oberti, R., Brumm, R., Foley, S., Vannucci, R.Trace element partitioning between synthetic potassic richterites and silicate melts, andEuropean Journal of Mineralogy, Vol. 15, 2, pp. 329-40.GlobalMineralogy
DS200412-1992
2003
Oberti, R.Tiepolo, M., Zanetti, A., Oberti, R., Brumm, R., Foley, S., Vannucci, R.Trace element partitioning between synthetic potassic richterites and silicate melts, and contrasts with the partitioning behaviEuropean Journal of Mineralogy, Vol. 15, 2, pp. 329-40.TechnologyMineralogy
DS200412-2197
2004
Oberti, R.Zanetti, A., Tiepolo, M., Oberti, R., Vannucci, R.Trace element partitioning in olivine: modelling of a complete dat a set from a synthetic hydrous basanite melt.Lithos, Vol. 75, 1-2, July, pp. 39-54.TechnologyGeochemistry - petrogenetic processes, fingerprinting
DS200612-0996
2006
Oberti, R.Oberti, R., Quartieri, S., Dalconi, M.C., Boscherini, F., Iezzi, G., Boiocchi, M., Eeckhout, S.G.Site preference and local geometry of Sc in garnets: part 1. multifarious mechanisms in the pyrope-grossular join.American Mineralogist, Vol. 91, 9, pp. 1230-1239.TechnologyMineral chemistry - garnets
DS201212-0002
2012
Oberti, R.Adam, J., Oberti, R., Camara, F., Green, T.H., Rushmer, T.The effect of water on equilibrium relations between clinopyroxenes and basanitic magmas: tracing water and non- volatile incompatible elements in the Earth's mantle.emc2012 @ uni-frankfurt.de, 1p. AbstractMantleMelting
DS1992-1685
1992
Obi, C.M.Wise, D.U., Obi, C.M.Laramide basement deformation in an evolving stress field, Bighorn MountainFront, Five Spring area, Wyoming.American Association of Petroleum Geologists Bulletin, Vol. 76, No. 10, October pp. 1586-1600.WyomingTectonics, Basement -general reference
DS200512-0790
2004
OblenskiyNokleberg, W.J., Bararch, G.Berzin, Diggles, Hwang, Khanchuk, Miller, Naumova, Oblenskiy, Ogasawara, ParfemicDigital files for northeast Asia, geodynamics, mineral deposit location and metallogenic belt maps. stratigraphic columns, map units.U.S. Geological Survey, Open file 2004-1252Russia, ChinaMaps - geodynamics - not specific to diamonds
DS1994-0433
1994
Obolenskii, A.A.Distanov, E.G., Obolenskii, A.A.Metallogenic development of the central Asian mobile belt in relation to its geodynamic evolutionRussian Geology and Geophysics, Vol. 35, No. 7-8, pp. 218-China, AsiaMetallogeny, Geodynamics
DS201112-0750
2011
Obrebski, M.Obrebski, M., Allen, R.M., Pollitz, F., Hung, S-H.Lithosphere asthenosphere interaction beneath the western United States from the joint inversion of body-wave traveltimes and surface wave phase veolocities.Geophysical Journal International, March 25, In press availableUnited StatesGeophysics - seismics
DS1989-0686
1989
O'Brieb, H.E.Irving, A.J., O'Brieb, H.E., McCallum, I.S.Precambrian mantle beneath Montana: geochemical evidence from Eocene volcanics and their xenolithsLpi Technical Report, No. 89-05, pp. 45-46MontanaMantle xenoliths, Age determinations
DS201603-0376
2016
Obrien, P.J.Ferrero, S., Ziemann, M.A., Angel, R.J., Obrien, P.J., Wunder, B.Kumdykolite, kokchetavite, and cristobalite crystallized in nanogranites from felsic granulites, Orlica-Snieznik Dome, ( Bohemian Massif): not an evidence for ultrahigh-pressure conditions.Contributions to Mineralogy and Petrology, Vol. 171, pp. 1-12.EuropeBohemian

Abstract: A unique assemblage including kumdykolite and kokchetavite, polymorphs of albite and K-feldspar, respectively, together with cristobalite, micas, and calcite has been identified in high-pressure granulites of the Orlica-Snieznik dome (Bohemian Massif) as the product of partial melt crystallization in preserved nanogranites. Previous reports of both kumdykolite and kokchetavite in natural rocks are mainly from samples that passed through the diamond stability field. However, because the maximum pressure recorded in these host rocks is <3 GPa, our observations indicate that high pressure is not required for the formation of kumdykolite and kokchetavite, and their presence is not therefore an indicator of ultrahigh-pressure conditions. Detailed microstructural and microchemical investigation of these inclusions indicates that such phases should instead be regarded as (1) a direct mineralogical criteria to identify former melt inclusions with preserved original compositions, including H2O and CO2 contents and (2) indicators of rapid cooling of the host rocks. Thus, the present study provides novel criteria for the interpretation of melt inclusions in natural rocks and allows a more rigorous characterization of partial melts during deep subduction to mantle depth as well as their behavior on exhumation.
DS1989-0609
1989
O'BrienHearn, B.C.Jr., Dudas, F.O., Eggler, D.H., Hyndman, D.W. , O'BrienMontana high pressureotassium igneous province. Crazy Mountains to Montana. July 20-27American Geophysical Union (AGU) 28th. International Geological Congress Field Trip Guidebook, No. T 346, 86pMontanaHighwood Mountains, Minettes, Shonkinites, Lamproites
DS1990-1419
1990
O'BrienStockmal, G.S., Colman-Sadd, Keen, C.E., Marillier, F., O'BrienDeep seismic structure and plate tectonic evolution of the CanadianAppalachiansTectonics, Vol. 9, No. 1, February pp. 45-62AppalachiaTectonics, Geophysics-seismics
DS201212-0488
2012
O'Brien, D.P.Morbidelli, A., Lunine, J.I., O'Brien, D.P., Raymond, S.N., Walsh, K.J.Building terrestrial planets.Annual Review of Earth and Planetary Sciences, Vol. 40, pp. 251-275.MantleTectonics
DS201412-0306
2014
O'Brien, D.P.Goodrich, C., Bischoff, A., O'Brien, D.P.Asteroids: establishing asteroid-meteorite links.Elements, Vol. 10, 1, pp. 25-30.TechnologyAsteroids
DS1997-1178
1997
O'Brien, H.Tyni, M., O'Brien, H.Prospecting for Diamondiferous kimberlites in FinlandVuoriteollisus, Vol. 55, No. 3, pp. 26-29.FinlandOverview, Prospecting
DS200512-0795
2005
O'Brien, H.O'Brien, H.Diamond prospectivity of the Karelian Craton of Finland.PDAC 2005, Abstract 1p.Europe, FinlandBrief overview abstract
DS200612-0997
2004
O'Brien, H.O'Brien, H., Ramo, T., Gehor, S.Carbonatite-kimberlite-alkaline rock field trip to southern and central Finland.Siilinjarvi, Kaavi-Kuopio, Kuhmo, IivaaraFinland Field Trip Guidebook June 2-4, 2004, 30p.Europe, FinlandGuidebook
DS200912-0432
2009
O'Brien, H.Lehtonen, M., O'Brien, H., Peltonen, P., Kukkonen, I., Ustinov, V., Verzhak, V.Mantle xenocrysts from the Arkangelskaya kimberlite (Lomonosov); constraints on the composition and thermal state of the Diamondiferous lithospheric mantle.Lithos, in press availableRussia, Kola Peninsula, ArchangelDeposit - Lomonosov
DS200912-0870
2009
O'Brien, H.Zozulya, D.R., Mitrofanov, F.P., Peltonen, P., O'Brien, H., Lehtonen, M., Kalachev, V.Yu.Lithospheric mantle structure and diamond prospects in the Kola region: chemical and thermobarometric analyses of kimberlite pyrope.Doklady Earth Sciences, Vol. 427, 5, pp. 746-750.Russia, Kola PeninsulaGeothermometry
DS200912-0871
2008
O'Brien, H.Zozulya, D.R., Peltonen, P., O'Brien, H.Pyrope and Cr-diopside as indicators of mantle structure and diamond depth facies in the Kola region.Geology of Ore Deposits, Vol. 50, 7, pp. 524-534.Russia, Kola Peninsula, ArchangelTectonics
DS200912-0872
2009
O'Brien, H.Zozulya, D.R., Peltonen, P., O'Brien, H., Lehtonen, M.Lithospheric roots and asthenospheric upwarps of the NE Baltic Shield: spatial controls for kimberlitic and alkaline magmatism.alkaline09.narod.ru ENGLISH, May 10, 2p. abstractEurope, Baltic Shield, Kola PeninsulaMagmatism
DS200912-0873
2009
O'Brien, H.Zozulya, D.R., Peltonen, P., O'Brien, H., Lehtonen, M.Mantle depth facies of high pressure pyroxene in the Kola region.Doklady Earth Sciences, Vol. 424, 1, pp. 52-56.Russia, Kola PeninsulaMineralogy
DS201012-0432
2009
O'Brien, H.Lehtonen, M., O'Brien, H.Mantle transect of the Karelian craton from margin to core based on P-T dat a from garnet and clinopyroxene xenocrysts in kimberlites.Bulletin of the Geological Society of Finland, Vol. 81, pp. 79-102.Europe, FinlandGeochemistry
DS201012-0636
2010
O'Brien, H.Romu, I., Luttinen, A., O'Brien, H.Ultrapotassic dyke swarm of Vestfjella, western Dronning Maud Land, Antartica.International Dyke Conference Held Feb. 6, India, 1p. AbstractAntarcticaLamproites - Orangeites
DS201012-0897
2009
O'Brien, H.Zozulya, D.R., O'Brien, H., Peltonen, P., Lehtonen, M.Thermobarometry of mantle derived garnets and pyroxenes of Kola region ( NW Russia): lithosphere composition, thermal regime and diamond prospectivity.Bulletin of the Geological Society of Finland, Vol. 81, pp. 143-158.Russia, Kola PeninsulaGeothermometry
DS201012-0898
2009
O'Brien, H.Zozulya, D.R., O'Brien, H., Peltonen, P., Lehtonen, M.Thermobarometry of mantle derived garnets and pyroxenes of Kola region ( NW Russia): lithosphere composition, thermal regime and diamond prospectivity.Bulletin of the Geological Society of Finland, Vol. 81, pp. 143-158.Russia, Kola PeninsulaGeothermometry
DS201212-0526
2012
O'Brien, H.O'Brien, H., Lehtonen, M.Craton mantle formation and structure of eastern FIn land mantle: evidence from kimberlite-derived mantle xenoliths, xenocrysts and diamonds.Springer Lecture Notes in Earth Sciences From the Earth's core to Outer space, editor Haapala, I., Vol. 137, pp. 61-80.Europe, FinlandKimberlite xenoliths
DS201312-0007
2013
O'Brien, H.Afanasiev, V.P., Aschepkov, I.V., Verzhak, V.V., O'Brien, H., Palessky, S.V.PT conditions and trace element variations of picroilmenites and pyropes from placers and kimberlites in the Arkhangelsk region, NW Russia.Journal of Asian Earth Sciences, Vol. 70, pp. 45-63.Russia, Kola Peninsula, ArchangelDeposit - Verkhotinskoe , Kepinskoe fields
DS201604-0620
2015
O'Brien, H.O'Brien, H.Mineral Deposits of FIn land Chapter 4.4 Kimberlite hosted diamonds in FIn land.Mineral Deposits of Finland, pp. 345-375.Europe, FinlandKimberlite - deposits

Abstract: The levels of brilliance (brightness and contrast), fire (flashes of rainbow color), and scintillation (intense sparkles when moved) of diamonds are unmatched by any other gemstone. Also diamonds of gem size and quality are relatively rare. As a result, gem diamonds are extremely valuable, yet the supply of diamonds is ultimately limited. This reality has pushed diamond exploration and mining into extreme environments, from the far Arctic North to the deserts of southern Africa and onto the ocean bed off the coast of Namibia. About two-thirds of the annual production of diamonds by weight comes from ancient volcanoes that consist of the rock types kimberlite, orangeite, or lamproite. Tracking down the remnants of these small volcanoes requires sophisticated and efficient collection and processing of samples for kimberlite indicator minerals (i.e., peridotite constituent minerals) and evaluation of enormous amounts of mineral data to constrain the diamond prospectivity of a region, cluster of pipes, or particular diatreme. The exploration sampling stage is usually followed by aero- or ground-geophysical measurements, target evaluation, and, finally, drill testing. Diamond exploration is expensive, but the rewards can be great. Diamond exploration in Finland started in 1985, and has been continuous, albeit with varying levels of activity, since that time. As a result, diamondiferous rocks have been found in three regions—namely, the Kuhmo-Lentiira area hosting a group of 1200 Ma orangeites, the Kuusamo-Hossa area containing several 760 Ma kimberlites, and the Kaavi-Kuopio area with a cluster of ~600 Ma kimberlites. Driven by the needs of these exploration activities, our understanding of the makeup of the Karelian craton, and our understanding of the magmas that have transported diamonds to the surface in this part of the world have benefitted enormously.
DS201705-0874
2017
O'Brien, H.Smart, K.A., Cartigny, P., Tappe, S., O'Brien, H., Klemme, S.Lithospheric diamond formation as a consequence of methane rich volatile flooding: an example from Diamondiferous eclogite xenoliths of the Karelian craton ( Finland).Geochimica et Cosmochimica Acta, Vol. 206, pp. 312-342.Europe, FinlandDeposit - Lahtojoki

Abstract: A collection of 61 xenocrystic and 12 eclogite xenolith-derived diamonds from the 600 Ma Lahtojoki kimberlite in central Finland has been investigated. Calculated pressure and temperature conditions for the diamondiferous eclogites are in excess of 5.5 GPa and 1300 °C, suggesting residence depths greater than 180 km, near the base of the Karelian cratonic mantle lithosphere. Geochemically, the eclogite xenoliths have gabbroic compositions showing positive Eu and Sr anomalies, relatively low SREE and elevated Al2O3 contents, yet garnets have ambiguous d18O values of 5.7‰ and 5.9‰. Gabbroic eclogite formation could therefore be linked to either subduction processes during the 1.9 Ga Svecofennian orogeny or to cumulate processes during 2.1 Ga rift-induced magmatism. Determination of the oxygen fugacity of Lahtojoki eclogite xenoliths from both this work and previous studies suggests that diamond-bearing eclogites may be more reduced (?FMQ-3.5) compared to barren eclogites (?FMQ-1.7). While recycled oceanic crust protoliths for the eclogites remain a possibility, the carbon isotopic compositions and nitrogen abundances of the Lahtojoki diamonds indicate mantle-derived volatile sources. All diamonds (i.e., loose and eclogite xenolith-derived) display a restricted range of d13C values from -7.8‰ to -3.7‰ that overlaps with the carbon isotopic composition of Earth’s mantle. The Lahtojoki diamond d13C values form a negatively skewed distribution, indicating diamond growth from reduced mantle-derived carbon sources such as methane- (CH4) bearing fluids. Nitrogen contents of the Lahtojoki diamonds range from 40 to 1830 atomic ppm with a mean of ~670 atomic ppm; these elevated nitrogen contents combined with the close association to eclogites suggest an eclogitic or crustal volatile source. However, the Karelian craton was periodically intruded by ultramafic alkaline magmas since at least 1.8 Ga, noting in particular the occurrence of phlogopite-rich kimberlites and olivine lamproites between 1200 and 700 Ma. We argue that this punctuated volatile-rich magmatism simultaneously metasomatised the cratonic mantle lithosphere, forming nitrogen enriched phlogopite-bearing metasomes. We propose that reduced, carbon-bearing and nitrogen-rich fluids were remobilized to form the Lahtojoki diamonds. The diamond-forming event(s) most probably occurred during or shortly prior to the entraining kimberlite magmatism as indicated by the diamond nitrogen aggregation systematics. Involvement of reduced diamond-forming fluids is supported by both the negative skewness of Lahtojoki diamond d13C values and the more reduced nature of the diamondiferous Lahtojoki eclogites compared with their more oxidized barren counterparts. Our results from the diamondiferous eclogites derived from the deepest parts of the Karelian cratonic mantle root are in support of methane being the stable carbon volatile species at the base of thick continental lithosphere.
DS201709-2029
2017
O'Brien, H.Maier, W.D., O'Brien, H., Peltonen, P., Barnes, S-J.Platinum group element contents of Karelian kimberlites: implications for the PGE budget of the sub-continental lithospheric mantle.Geochimica et Cosmochimica Acta, in press available, 14p.Europe, Finlanddeposit - Kaavi

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

Abstract: We present high-precision isotope dilution data for Os, Ir, Ru, Pt, Pd and Re in Group I and Group II kimberlites from the Karelian craton, as well as 2 samples of the Premier Group I kimberlite pipe from the Kaapvaal craton. The samples have, on average, 1.38 ppb Pt and 1.33 ppb Pd, with Pt/Pd around unity. These PGE levels are markedly lower, by as much as 80%, than those reported previously for kimberlites from South Africa, Brazil and India, but overlap with PGE results reported recently from Canadian kimberlites. Primitive-mantle-normalised chalcophile element patterns are relatively flat from Os to Pt, but Cu, Ni and, somewhat less so, Au are enriched relative to the PGE (e.g., Cu/Pd > 25.000). Pd/Ir ratios are 3,6 on average, lower than in most other mantle melts. The PGE systematics can be largely explained by two components, (i) harzburgite/lherzolite detritus of the SCLM with relatively high IPGE (Os-Ir-Ru)/PPGE (Rh-Pt-Pd) ratios, and (ii) a melt component that has high PPGE/IPGE ratios. By using the concentrations of iridium in the kimberlites as a proxy for the proportion of mantle detritus in the magma, we estimate that the analysed kimberlites contain 3-27% entrained and partially dissolved detritus from the sub-continental lithospheric mantle, consistent with previous estimates of kimberlites elsewhere (Tappe S. et al., 2016, Chem. Geol. http://dx.doi.org/10.1016/j.chemgeo.2016.08.019). The other major component in the samples is melt, modelled to contain an average of 0.85 ppb Pt and 1.09 ppb Pd. Assuming that Group II kimberlites are derived from relatively metasomatised SCLM, our data suggest that the metasomatised Karelian SCLM is relatively poor in Pt and Pd. If our data are representative of other Group II kimberlites elsewhere, this result could imply that the PGE enrichment in certain continental large igneous provinces, including Bushveld, is not derived from melting of metasomatised SCLM.
DS201805-0967
2007
O'Brien, H.O'Brien, H., Philippips, D., Spencer, R.Isotopic ages of Lentiira-Kuhmo-Kostomuksha olivine lamproite - Group II kimberlites NOTE Date of publ. Bulletin of the Geological Survey of Finland, Vol. 79, 2, pp. 203-215.Europe, Finlanddeposit - Lentiira Kuhmo

Abstract: The Lentiira-Kuhmo-Kostomuksha triangle, along the Finland - Russian border and within the central part of the Archean Karelian craton, contains numerous examples of phlogopite-rich, ultramafic, mantle-xenocryst-bearing and, in some cases, diamond-bearing dike rocks. Laser probe Ar-Ar data on phlogopite from 3 dike rocks on the Finnish side (Lentiira, Kuhmo) all gave ages within error of each other, 1202 ± 3 Ma (2s), 1199 ± 3 Ma (2s) and 1204 ± 4 Ma (2s) while a fourth sample produced mixed ages. Published Rb-Sr dates on mineralogically and chemically similar dikes from the Russian side (Kostomuksha) are 1232 ± 5 Ma. The question remains open whether these represent two distinct age populations or whether differences in isotopic system behavior are the reason for the 30 m.y. age difference.
DS201809-2088
2018
O'Brien, H.Smart, K.A., Cartigny, P., Tappe, S., O'Brien, H., Klemme, S.Reduced volatile sources for Karelian diamonds linked to punctuated ultramafic magmatism. LahtojokiGoldschmidt Conference, 1p. AbstractEurope, FinlandDeposit - Lahtojoki

Abstract: Diamond xenocrysts and eclogite-hosted diamonds from the Lahtojoki kimberlite (Karelian craton, Finland) indicate metasomatism of the deep lithosphere by N-rich, relatively reduced fluids. P-T-fO2 constraints show that all eclogites were derived from near the base of the lithospheric mantle (>5 GPa), but only the diamond-bearing samples are relatively reduced (?FMQ-3.5 vs. -1.7 for barren eclogites). The Lahtojoki diamonds show evidence of formation from reduced mantle-derived carbon, based on the restricted range of ?13C values (-3 and -7.8 ‰; n = 67) that form a negativelyskewed distribution. This reduced CHO fluid was also anomalously N-rich, based on the diamond N contents that range up to 1830 at. ppm. While N-rich sources for eclogiteassociated diamonds are often linked to recycled crustal materials, in this case we prefer derivation from K-rich cratonic mantle metasomes due to lack of firm crustal geochemical signatures in the eclogites (?18O = 5.7 - 5.9 ‰), in addition to the magmatic history of the Karelian craton. The Karelian craton has been periodically intruded by Krich alkaline lamprophyres, Group-2 kimberlites and olivine lamproites from 1800 to 700 Ma. Such K-rich ultramafic alkaline magmatism is likely linked to phlogopite-rich metasomes, which may represent significant repositories of N (NH4+ substitution for K+). Because the Lahtojoki eclogites resided near the base of the lithospheric mantle, they would have been susceptible to interaction with ascending asthenosphere-derived C-bearing fluids/melts, which were reducing. Following ingress into and interaction with the Krich metasomatised Karelian mantle lithosphere, the increasingly N-enriched, CH4-bearing fluids precipitated diamond during interaction with relatively oxidized eclogite wall rock. In contrast to the prevalent oxidizing effects of mantle metasomatism as identified within cratonic lithosphere-derived samples from worldwide locations, the eclogite-hosted diamonds at Lahtojoki represent a natural example of metasomatic overprinting that was highly reducing.
DS201910-2253
2019
O'Brien, H.Dalton, H., Giuliani, A., Phillips, D., Hergt, J., O'Brien, H.Petrographic and geochemical variations in the Kaavi-Kuopio kimberlite field, Finland: the role of mantle assimilation.Goldschmidt2019, 1p. AbstractEurope, Finlanddeposit - Kaavi-Kuopio

Abstract: Kimberlites are silica-poor, volatile-rich (CO2 ± H2O), volcanic rocks that are often described as ‘hybrid’, because their parental magmas include abundant xenocrystic (crustand mantle-derived) components. Unravelling the influence of mantle assimilation on kimberlite melt compositions represents an outstanding question of kimberlite petrology. To address this issue, we have carried out a comprehensive geochemical and petrographic investigation of nine kimberlites from the Kaavi-Kuopio field in Finland, that were emplaced on the southern margin of the Karelian Craton in the Neoproterozoic (~550-600 Ma). Olivine is the dominant mineral phase in kimberlites (~50 vol.%) with cores mainly derived from the disaggregation of mantle peridotite. In contrast, olivine rims crystallise directly from the kimberlitic melt and their Mg# (Mg/(Mg+Fe)) typically show remarkable homogeneity within and between kimberlites of a single cluster and field (e.g., Lac de Gras). The Kaavi-Kuopio kimberlites appear to represent a unique case where there is a (statistically) significant difference between the average Mg# of olivine rims in different pipes (89.9 ± 0.2 to 88.5 ± 0.3). Importantly, the Mg# of olivine rims exhibit a strong correlation with the Mg# of olivine cores. Furthermore, the compositions of olivine cores (and rims) exhibit a strong correlation with those of spinel (e.g., Mg#, TiO2 contents). These geochemical variations correlate with the modal mineralogy of the kimberlites: for example, higher abundances of monticellite and lower abundances of ilmenite are associated with higher Mg# olivine. The robust relationship between entrained and assimilated lithospheric mantle material (i.e. olivine cores) and magmatic components (i.e. olivine rims, spinel, and other groundmass minerals) suggests that assimilation of lithospheric mantle has impacted the compositions of kimberlitic melts to a greater extent than previously recognised. These new data also suggest significant variations in the composition of the mantle lithosphere beneath the Kaavi-Kuopio kimberlites, which are spaced less than 10 km apart.
DS201912-2807
2019
O'Brien, H.Mitchell, R.H., Giulani, A., O'Brien, H.What is a kimberlite? Petrology and mineralogy of hypabyssal kimberlite.Elements, Vol. 15, 6, pp.Mantlediamond genesis

Abstract: Hypabyssal kimberlites are subvolcanic intrusive rocks crystallised from mantle-derived magmas poor in SiO2 and rich in CO2 and H2O. They are complex, hybrid rocks containing significant amounts of mantle-derived fragments, primarily olivine with rare diamonds, set in a matrix of essentially magmatic origin. Unambiguous identification of kimberlites requires careful petrographic examination combined with mineral compositional analyses. Melt inclusion studies have shown that kimberlite melts contain higher alkali concentrations than previously thought but have not clarified the ultimate origin of these melts. Because of the hybrid nature of kimberlites and their common hydrothermal alteration by fluids of controversial origin (magmatic and/or crustal), the composition of primary kimberlite melts remains unknown.
DS202002-0173
2019
O'Brien, H.Dalton, H., Giuliani, A., O'Brien, H., Phillips, D., Hergt, J.The role of lithospheric heterogeneity on the composition of kimberlite magmas from a single field: the case of Kaavi-Kuopio, Finland.Lithos, in press available, 61p. PdfEurope, Finlanddeposit - Kaavi-Kuopio

Abstract: Kimberlites are complex, ‘hybrid’ igneous rocks because their parental magmas entrain abundant crust- and mantle-derived components that can be readily assimilated during ascent to surface. Recent studies of olivine zonation patterns have shown compositional relationships between xenocrystic cores and magmatic rims, suggesting that kimberlite melt compositions might be controlled by assimilation of mantle material during emplacement. However, the nature and extent to which this process, as well as assimilation of crustal material, influences melt compositions within single kimberlite fields remains unclear. To address this issue, we have conducted a comprehensive geochemical and petrographic investigation of kimberlites from eight pipes in the Kaavi-Kuopio field in Finland, which were emplaced on the southern margin of the Karelian craton during the Neoproterozoic (~550-600 Ma). While magmatic olivine rims are usually homogeneous in composition within and between kimberlites of a single cluster and field (e.g., Lac de Gras), the Kaavi-Kuopio kimberlites appear to represent a unique case where there are statistically significant differences between the average Mg# of olivine rims in different pipes (89.9 ± 0.2 to 88.5 ± 0.3). Importantly, the Mg# of magmatic olivine rims exhibit a strong correlation with the Mg# of their mantle-derived xenocrystic cores. Furthermore, the compositions of olivine cores and rims exhibit a robust relationship with those of magmatic spinel (e.g., Mg#, TiO2 contents). These geochemical variations also align with the mineralogy of the kimberlites: whereby abundances of phlogopite and oxides (e.g., spinel) are negatively correlated with olivine rim Mg#. The robust relationship between entrained and assimilated lithospheric mantle material (i.e. olivine cores) and magmatic components (i.e. olivine rims, spinel, and groundmass mineral abundance), combined with numerical modelling suggests that up to 10 wt% assimilation of lithospheric mantle material has modified the compositions of the Kaavi-Kuopio kimberlites. These new data are also consistent with significant variations in the lithospheric mantle composition of the Karelian craton beneath the closely spaced (<10 km) kimberlites. Finally, in addition to mantle assimilation, formation of Si-Fe-rich mica in some of the examined kimberlites might be linked to late-stage increases in oxygen fugacity potentially enhanced by crustal contamination. This study shows for the first time that variable assimilation of mantle and crustal material can generate significant variations in kimberlites derived from seemingly similar sources.
DS202002-0174
2019
O'Brien, H.Dalton, H., Giuliani, A., O'Brien, H., Phillips, D., Maas, R. Petrogenesis of a hybrid cluster of evolved kimberlites and ultramafic lamprophyres in the Kuusamo area, Finland. Kasma 45, Kasma 45 south, Kasma 47, Kalettomanpuro, Kattaisenvaara, Dike 15 and LampiJournal of Petrology, in press available, 79p. PdfEurope, Finlanddeposit - Kuusamo

Abstract: Kimberlites are often closely associated, both in time and space, with a wide variety of alkaline ultramafic rock types; yet the question of a genetic relationship between these rock types remains uncertain. One locality where these relationships can be studied within the same cluster is the Karelian craton in Finland. In this study we present the first petrographic, mineral and whole-rock geochemical results for the most recently discovered kimberlite cluster on this craton, which represents an example of the close spatial overlap of kimberlites with ultramafic lamprophyres. The Kuusamo cluster incorporates seven bodies (Kasma 45, Kasma 45 south, Kasma 47, Kalettomanpuro (KP), Kattaisenvaara (KV), Dike 15 and Lampi) distributed along a 60?km NE-SW corridor. Hypabyssal samples from KV, KP, Kasma 45 and Kasma 47 consist of altered olivine macrocrysts and microcrysts and phlogopite phenocrysts in a groundmass of perovskite, apatite, spinel, ilmenite, serpentine, and calcite. These petrographic features combined with mineral (e.g., Mg-rich ilmenite, Al-Ba-rich, Ti-Fe-poor mica) and whole-rock incompatible trace element compositions (La/Nb = 0.8 ± 0.1; Th/Nb = 0.07 ± 0.01; Nb/U = 66 ± 9) are consistent with these rocks being classified as archetypal kimberlites. These Kuusamo kimberlites are enriched in CaO and poor in MgO, which combined with the absence of chromite and paucity of olivine macrocrysts and mantle-derived xenocrysts (including diamonds), suggest derivation from differentiated magmas after crystal fractionation. Samples from Lampi share similar petrographic features, but contain mica with compositions ranging from kimberlitic (Ba-Al-rich cores) to those more typical of orangeites/lamproites (increasing Si-Fe, decreasing Al-Ti-Ba), and have higher bulk-rock SiO2 contents than the Kuusamo kimberlites. These features, combined with the occurrence of quartz and titanite in the groundmass, indicate derivation from a kimberlite magma that underwent considerable crustal contamination. This study shows that crustal contamination can modify kimberlites by introducing features typical of alkaline ultramafic rock types. Dike 15 represents a distinct carbonate-rich lithology dominated by phlogopite over olivine, with lesser amounts of titaniferous clinopyroxene and manganoan ilmenite. Phlogopite (Fe-Ti-rich) and spinel (high Fe2+/Fe2++Mg) compositions are also distinct from the other Kuusamo intrusions. The petrographic and geochemical features of Dike 15 are typical of ultramafic lamprophyres, specifically, aillikites. Rb-Sr dating of phlogopite in Dike 15 yields an age of 1178.8 ± 4.1?Ma (2s), which is considerably older than the ~750?Ma emplacement age of the Kuusamo kimberlites. This new age indicates significant temporal overlap with the Lentiira-Kuhmo-Kostomuksha olivine lamproites emplaced ~100?km to the southeast. It is suggested that asthenospheric aillikite magmas similar to Dike 15 evolved to compositions akin to the Karelian orangeites and olivine lamproites through interaction with and assimilation of MARID-like, enriched subcontinental lithospheric mantle. We conclude that the spatial coincidence of the Kuusamo kimberlites and Dike 15 is likely the result of exploitation of similar trans-lithospheric corridors.
DS202008-1383
2020
O'Brien, H.Dalton, H., Giuiani, A., Phillips, D., Hergt, J., Maas, R., Woodhead, J., Matchan, E., O'Brien, H.Kimberlite magmatism in Finland: distinct sources and links to the breakup of Rodinia.Goldschmidt 2020, 1p. AbstractEurope, Finlanddeposit - Kuusamo

Abstract: The Karelian Craton in Finland is host to (at least) two distinct pulses of kimberlite magmatism. Twenty kimberlite occurrences have so far been discovered on the southwest margin of the craton at Kaavi-Kuopio and seven kimberlites are located in the Kuusamo area within the core of the craton. Comprehensive radiometric age determinations (U-Pb, Ar- Ar and Rb-Sr) reveal that all kimberlite activity was restricted to the Proterozoic. The Kaavi-Kuopio field was emplaced over a protracted period from ~610 to 550 Ma and is predated by the Kuusamo cluster that represents a relatively short pulse of magmatism at ~750 to 730 Ma. The emplacement of kimberlites globally has recently been linked to supercontinent reorganisation and we propose a similar scenario for these Finnish occurrences which, at the time of kimberlite emplacement, were situated on the Baltica paleo-continent. This land mass was contiguous with Laurentia in the Proterozoic and together formed part of Rodinia. The breakup of Rodinia is considered to have commenced at ~750 Ma and initiation of the opening of the Iapetus ocean at ~615 Ma. Contemporaneous with Kaavi-Kuopio magmatism, this latter period of Neoproterozoic crustal extension also includes the emplacement of kimberlites and related rocks in areas that were linked with Baltica as part of Rodinia - West Greenland and eastern North America. Both the initial and final periods of Rodinia’s breakup have been linked to mantle upwellings from the core-mantle boundary. We suggest that kimberlite magmatism in Finland was promoted by the influx of heat from mantle upwellings and lithospheric extension associated with the demise of Rodinia. Although both magmatic episodes are potentially linked to the breakup of Rodinia, whole-rock and perovskite radiogenic isotope compositions for the Kuusamo kimberlites (eNd(i) +2.6 to +3.3, eHf(i) +3.1 to +5.6) are distinct from the Kaavi-Kuopio kimberlites (eNd(i) -0.7 to +1.8, eHf(i) -6.1 to +5.2). The spread in Hf isotope compositions for the Kaavi-Kuopio magmas may be linked to variable assimilation of diverse mantle lithologies.
DS202008-1405
2020
O'Brien, H.Kara, J., Vaisanen, M., Heinonen, J.S., Lahaye, Y., O'Brien, H., Huhma, H.Tracing arcologites in the Paleoproteroic era - a shift from 1.88 Ga calc-alkaline to 1.86 Ga high-Nb and adakite-like magmatism in central Fennoscandian shield.Lithos, in press available, 68p. PdfEurope, Fennoscandiaalkaline
DS200912-0869
2009
O'Brien, H.A.Zozulya, D.A.R.A., Peltonen, S.A.P.A., O'Brien, H.A., Lehtonen, M.A.Kimberlite depth facies of high pressure pyroxene in the Kola region.Doklady Earth Sciences, Vol. 425, 2, pp. 350-352.Russia, Kola PeninsulaUHP
DS1985-0502
1985
O'brien, H.E.O'brien, H.E., Irving, A.J., Mccallum, I.S.Complex Zoning of Clinopyroxene in Shonkinites from Mafic Phonolites, Highwood Mountains, Montana: Evidence for Periodic Mixing with a K Rich Bananitic Magma.Geological Society of America (GSA), Vol. 17, No. 3, P. 187. (abstract.).United States, Montana, Rocky MountainsMineralogy
DS1986-0615
1986
O'Brien, H.E.O'Brien, H.E., Irving, A.J., McCallum, I.S.Evolution og minette, lamproite and mafic phonolite magmas in the Highwood Mountains province, Montana USA: geochemical andmineralogicalevidenceProceedings of the Fourth International Kimberlite Conference, Held Perth, Australia, No. 16, pp. 199-201MontanaBlank
DS1987-0543
1987
O'Brien, H.E.O'Brien, H.E., Irving, A.J., McCallum, I.S.Geochemical evidence for ancient enriched and eocene arc components In the source region of the Highwood mountains potassic volcanics, MontanaTerra Cognita, Conference abstracts Oceanic and Continental Lithosphere:, Vol. 7, No. 4, Autumn, abstract only p. 621MontanaBlank
DS1989-0687
1989
O'Brien, H.E.Irving, A.J., O'Brien, H.E., McCallum, I.S.Montana potassic volcanism: geochemical evidence for interaction of asthenopsheric melts and meta-somatically-veinedPrec. subcontinental mantlelithNew Mexico Bureau of Mines Bulletin., Continental Magmatism Abstract Volume, Held, Bulletin. No. 131, p. 140 Abstract held June 25-July 1MontanaVolcanology, Mantle
DS1989-1144
1989
O'Brien, H.E.O'Brien, H.E.Petrogenesis of the mafic potassic rocks of the Highwood Mountains, MontanaPh.D. Thesis, University of Washington, Seattle, 379pMontanaHighwood, Petrogenesis
DS1991-0772
1991
O'Brien, H.E.Irving, A.J., O'Brien, H.E.Isotopic and trace element remote sensing of Montana continental lithosphere from erupted magmasProceedings of Fifth International Kimberlite Conference held Araxa June 1991, Servico Geologico do Brasil (CPRM) Special, pp. 188-189MontanaMissouri Breaks, Haystack Butte, Indian Flats, Highwood, Bearpaw, Volcano Butte, Black Butte, Smoky Butte, lamproite
DS1991-1247
1991
O'Brien, H.E.O'Brien, H.E., Irvingm A.J., McCallum, J.S.Eocene potassic magmatism in the Highwood Mountains, Montana: petrology, geochemistry and tectonic implicationsJournal of Geophysical Research, Vol. 96, No. B8, July 30, pp. 13, 237-13, 260MontanaHighwood Mountains, Alkaline rocks
DS1994-0810
1994
O'Brien, H.E.Irving, A.J., O'Brien, H.E.Geochemistry of mafic shoshonitic Adel Mountain volcanics, Montana. Late Cretaceous arc related magma.Geological Society of America (GSA) Abstract Volume, Vol. 26, No. 7, ABSTRACT only p. A40.MontanaIgneous petrology, Shoshonites
DS1995-1371
1995
O'Brien, H.E.O'Brien, H.E., Irving, A.J., Thirlwall, M.F.Strontium, neodymium, lead isotope evidence for interaction post subduction asthenospheric potassic mafic magmas....Geochimica et Cosmochimica Acta, Vol. 59, No. 21, Nov. 1, pp. 4539-62.MontanaHighwood Mountains, Wyoming craton, mantle
DS1997-0861
1997
O'Brien, H.E.O'Brien, H.E., Tyni, M.Petrology of an unusual ortho-pyroxene bearing minette suite from selenium - Al rich lamproites ... granitesPapunen: 4th. Biennial SGA Meeting, pp. 781-783.FinlandDiamond exploration, Malmikaivos Oy, orangeite
DS1998-1088
1998
O'Brien, H.E.O'Brien, H.E., Tyni, M.Mineralogy and geochemistry of kimberlites and related rocks from FIn land #17th. Kimberlite Conference abstract, pp. 643-5.FinlandGeochemistry, Deposit - Kaavi, Kuopio
DS1999-0520
1999
O'Brien, H.E.O'Brien, H.E., Tyni, M.Mineralogy and geochemistry of kimberlites and related rocks from Finland7th International Kimberlite Conference Nixon, Vol. 2, pp. 625-36.FinlandHistory, mineral chemistry, analyses, Koidu, Aries
DS2003-0755
2003
O'Brien, H.E.Kuehner, S.M., Irving, A.J., O'Brien, H.E.A kalborsite pitiglianoite kalsilite shcherbakovite barytolam prophyllite wadeite bearing8 Ikc Www.venuewest.com/8ikc/program.htm, Session 7, POSTER abstractMontanaBlank
DS2003-0791
2003
O'Brien, H.E.Lehtonen, M.L., O'Brien, H.E., Peltonen, P., Johanson, B.S., Pakkanen, L.K.Layered mantle at the edge of the Karelian craton: P-T of mantle xenocrysts and8 Ikc Www.venuewest.com/8ikc/program.htm, Session 6, POSTER abstractFinlandBlank
DS2003-1025
2003
O'Brien, H.E.O'Brien, H.E., Lehtonen, M.L., Spencer, R.G., Birnie, A.C.Lithospheric mantle eastern Finland, a 240 km 3D transect8 Ikc Www.venuewest.com/8ikc/program.htm, Session 8, AbstractFinlandDiamond exploration - geophysics, seismics
DS200412-1061
2003
O'Brien, H.E.Kuehner, S.M., Irving, A.J., O'Brien, H.E.A kalborsite pitiglianoite kalsilite shcherbakovite barytolam prophyllite wadeite bearing lamproitic dike from the northern Highw8 IKC Program, Session 7, POSTER abstractUnited States, MontanaKimberlite petrogenesis
DS200412-1111
2004
O'Brien, H.E.Lehtonen, M.L., O'Brien, H.E., Peltonen, B.S., Johanson, B.S., Pakkanen, L.K.Layered mantle at the Karelian Craton margin: P T of mantle xenocrysts and xenoliths from the Kaavi Kuopio kimberlites, Finland.Lithos, Vol. 77, 1-4, Sept. pp. 593-608.Europe, FinlandLithosphere, thermometry
DS200412-1112
2003
O'Brien, H.E.Lehtonen, M.L., O'Brien, H.E., Peltonen, P., Johanson, B.S., Pakkanen, L.K.Layered mantle at the edge of the Karelian craton: P-T of mantle xenocrysts and xenoliths from eastern FIn land kimberlites.8 IKC Program, Session 6, POSTER abstractEurope, FinlandMantle petrology
DS200412-1456
2003
O'Brien, H.E.O'Brien, H.E., Lehtonen, M.L., Spencer, R.G., Birnie, A.C.Lithospheric mantle eastern Finland, a 240 km 3D transect.8 IKC Program, Session 8, AbstractEurope, FinlandDiamond exploration - geophysics, seismics
DS200512-0796
2005
O'Brien, H.E.O'Brien, H.E., Peltonen, P., Vartiainen, H.Kimberlites, carbonatites and alkaline rocks.Elsevier: Lehtinen, M., Nurmi, P.A., Rama, O.T. eds. Precambrian geology of Finland: key to the evolution, pp.Europe, Finland, FennoscandiaOverview
DS200812-0500
2008
O'Brien, H.E.Illona Romu, K.R., Luttinen, A.V., O'Brien, H.E.Lamproite orangeite transition in 159 Ma dykes of Dronning Maud Land, Antarctica.9IKC.com, 3p. extended abstractAntarcticaLamproite
DS200812-0625
2008
O'Brien, H.E.Laine, H.M., O'Brien, H.E.Alteration and primary kimberlite rock type classification for Lahtojoki kimberlite, Finland.9IKC.com, 3p. extended abstractEurope, FinlandDeposit - Lahtojoki
DS200812-0809
2008
O'Brien, H.E.O'Brien, H.E., Bradley, J.New kimberlite discoveries in Kuusamo, northern Finland.9IKC.com, 3p. extended abstractEurope, FinlandDeposit - Kuusamo field
DS200812-0810
2008
O'Brien, H.E.O'Brien, H.E., Legtonen, M.L., Grimmer, S.G., McNulty, K., Peltonen, P., Kontinen, A.Kimberlites in Finland. Geology of kimberlites, carbonatites and alkaline rocks. Seitapera kimberlite and Jormua ophiolite complex.9th. IKC Field Trip Guidebook, CD 58p.Europe, FinlandGuidebook - kimberlites, carbonatites
DS201212-0457
2012
O'Brien, H.E.McNulty, W.K., O'Brien, H.E.Seitapera Group II kimberlite/olivine lamproite: large 1200 Ma Diamondiferous pipe in Kuhmo, eastern Finland.10th. International Kimberlite Conference Held Bangalore India Feb. 6-11, Poster abstractEurope, FinlandDeposit - Seitapera
DS201212-0527
2012
O'Brien, H.E.O'Brien, H.E., Birnie, A.C., Spencer, R.G.Diamondiferous megacrystal garnet and orthopyroxene from Liqhobong, Lesotho.10th. International Kimberlite Conference Held Bangalore India Feb. 6-11, Poster abstractAfrica, LesothoDeposit - Liqhobong
DS201212-0528
2012
O'Brien, H.E.O'Brien, H.E., Spencer, R.G.Lemphane kimberlite diamond project: petrology update.10th. International Kimberlite Conference Held Bangalore India Feb. 6-11, Poster abstractAfrica, LesothoDeposit - Lemphane
DS1998-1482
1998
O'Brien, P.Treloar, P.J., O'Brien, P.What drives metamorphism and metamorphic reactons?Geological Society of London Spec. Pub, No. 138, 240p. $ 115.00Europe, Spain, Japan, PakistanBook - ad, Metamorphism, barrovian
DS200612-0515
2006
O'Brien, P.Hacker, B., O'Brien, P.Continental crust subduction and recycling.Goldschmidt Conference 16th. Annual, S5-08 theme abstract 1/8p. goldschmidt2006.orgMantleSubduction
DS1991-1253
1991
O'Brien, P.J.Okrusch, M., Matthes, S., Klemd, R., O'Brien, P.J., Schmidt, K.Eclogites at the north-western margin of the Bohemian Massif: a reviewEuropean Journal of Mineralogy, Vol. 3, No. 4, pp. 707-730EuropeEclogites, Mineral chemistry
DS1993-1153
1993
O'Brien, P.J.O'Brien, P.J., Carswell, D.A.Tectonometamorphic evolution of the Bohemian Massif: evidence from high pressure metamorphic rocksGeologische Rundshau, Vol. 82, pp. 531-555Austria, GermanyTectonics, metamorphism
DS1993-1154
1993
O'Brien, P.J.O'Brien, P.J., Rohr, C., Okrusch, M., Patzak, M.Eclogite facies relics and a multistage breakdown in metabasites of the KTB pilot hole, northeast Bavaria: implications for the Variscan tectonometamorphic evolContributions to Mineralogy and Petrology, Vol. 112, pp. 261-278GlobalEclogites, metamorphism
DS1997-0169
1997
O'Brien, P.J.Carswell, D.A., O'Brien, P.J., Zhai, M.Thermobarometry of phengite bearing eclogites in the Dabie Mountains of central China.Journal of Met. Geology, Vol. 15, No. 2, Mar. 1, pp. 239-252.ChinaEclogites, Dabie Mountains
DS2000-0723
2000
O'Brien, P.J.O'Brien, P.J.ultra high pressure (UHP) metamorphism - prospecting for potential coesite bearing terranes with alternative geothermobarometric..Igc 30th. Brasil, Aug. abstract only 1p.NorwayCoesites
DS2001-0846
2001
O'Brien, P.J.O'Brien, P.J.Subduction followed by collision: Alpine and Himalayan examplesPhysics of the Earth and Planetary Interiors, Vol. 127, No. 1-4, Dec. 1, pp. 277-91.Alps, MantleSubduction, Tectonics, geodynamics
DS2001-0847
2001
O'Brien, P.J.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
DS2003-0220
2003
O'Brien, P.J.Carswell, D.A., Brueckner, H.K., Cuthbert, S.J., Mehta, K., O'Brien, P.J.The timing of stabilization and the exhumation rate for ultra high pressure rocks in theJournal of Metamorphic Geology, Vol. 21, 6, pp. 601-612.NorwayUHP
DS2003-0221
2003
O'Brien, P.J.Carswell, D.A., Tucker, R.D., O'Brien, P.J., Krogh, T.E.Coesite micro-inclusions and the U Pb age of zircons from the Hariedland eclogite inLithos, Vol. 67, 3-4, April pp. 181-190.NorwayCoesite
DS2003-0222
2003
O'Brien, P.J.Carswell, D.A., Tucker, R.D., O'Brien, P.J., Krogh, T.E.Coesite micro-inclusions and the U Pb age of zircons from the Hareidland eclogite inLithos, Vol.67, 3-4, April, pp. 181-190.NorwayGeochronology, UHP
DS2003-1389
2003
O'Brien, P.J.Treloar, P.J., O'Brien, P.J., Parrish, R.R., Khan, M.A.Exhumation of early Tertiary, coesite bearing eclogites from the Pakistan HimalayaJournal of the Geological Society of London, Vol. 160, 3, May pp. 367-76.PakistanEclogites
DS200412-0286
2003
O'Brien, P.J.Carswell, D.A., Brueckner, H.K., Cuthbert, S.J., Mehta, K., O'Brien, P.J.The timing of stabilization and the exhumation rate for ultra high pressure rocks in the Western Gneiss region of Norway.Journal of Metamorphic Geology, Vol. 21, 6, pp. 601-612.Europe, NorwayUHP
DS200412-0287
2003
O'Brien, P.J.Carswell, D.A., Tucker, R.D., O'Brien, P.J., Krogh, T.E.Coesite micro-inclusions and the U Pb age of zircons from the Hareidland eclogite in the Western Gneiss region of Norway.Lithos, Vol.67, 3-4, April, pp. 181-190.Europe, NorwayGeochronology, UHP
DS200412-2011
2003
O'Brien, P.J.Treloar, P.J., O'Brien, P.J., Parrish, R.R., Khan, M.A.Exhumation of early Tertiary, coesite bearing eclogites from the Pakistan Himalaya.Journal of the Geological Society, Vol. 160, 3, May pp. 367-76.PakistanEclogite
DS200712-0567
2007
O'Brien, P.J.Konrad-Schmolke, M., Zack, T., O'Brien, P.J.Trace element partitioning in subducted slabs: constraints from garnet inclusions and thermodynamic modelling.Plates, Plumes, and Paradigms, 1p. abstract p. A510.Mantle, NorwaySubduction, UHP
DS200812-0811
2008
O'Brien, P.J.O'Brien, P.J., Ziemann, M.A.Preservation of coesite in exhumed eclogite: insights from Raman mapping.European Journal of Mineralogy, Vol. 20, 5, pp. 827-834.MantleCoesite
DS201112-0545
2011
O'Brien, P.J.Kotkova, J., O'Brien, P.J., Ziemann, M.A.Discovery of diamond and coesite in Bohemian granulites.Goldschmidt Conference 2011, abstract p.1228.Europe, BohemiaEger Crystalline Complex, microdiamonds
DS201112-0546
2011
O'Brien, P.J.Kotkova, J., O'Brien, P.J., Ziemann, M.A.Diamond and coesite discovered in Saxony-type granulite: solution to the Variscan garnet peridotite enigma.Geology, Vol. 39, 7, pp. 667-670.EuropeSubduction - Bohemian diamond
DS201112-0929
2011
O'Brien, P.J.Schmidt, A., Mezger, K., O'Brien, P.J.The time of eclogite formation in the ultrahigh pressure rocks of the Sulu terrane constraints from Lu-Hf garnet geochronology.Lithos, Vol. 125, pp. 743-756ChinaUHP
DS201312-0783
2013
O'Brien, P.J.Schertl, H-P., O'Brien, P.J.Continental crust at mantle depths: key minerals and microstructures.Elements,, Vol. 9, 4, August pp. 261-266.MantleMineralogy
DS201506-0267
2015
O'Brien, P.J.Ferrero, S., Wunder, B., Walczak, K., O'Brien, P.J., Ziemann, M.A.Preserved near ultrahigh-pressure melt from continental crust subducted to mantle depths.Geology, Vol. 43, 5, pp. 447-450.MantleBohemian
DS201703-0402
2016
O'Brien, P.J.Ferrero, S., Wunder, B., Ziemann, M.A., Walle, M., O'Brien, P.J.Carbonatitic and granitic melts produced under conditions of primary immiscibility during anatexis in the lower crust. Oberpfalz areaEarth and Planetary Science Letters, Vol. 454, pp. 121-131.Europe, Czech RepublicBohemian Massif

Abstract: Carbonatites are peculiar magmatic rocks with mantle-related genesis, commonly interpreted as the products of melting of CO2-bearing peridotites, or resulting from the chemical evolution of mantle-derived magmas, either through extreme differentiation or secondary immiscibility. Here we report the first finding of anatectic carbonatites of crustal origin, preserved as calcite-rich polycrystalline inclusions in garnet from low-to-medium pressure migmatites of the Oberpfalz area, SW Bohemian Massif (Central Europe). These inclusions originally trapped a melt of calciocarbonatitic composition with a characteristic enrichment in Ba, Sr and LREE. This interpretation is supported by the results of a detailed microstructural and microchemical investigation, as well as re-melting experiments using a piston cylinder apparatus. Carbonatitic inclusions coexist in the same cluster with crystallized silicate melt inclusions (nanogranites) and COH fluid inclusions, suggesting conditions of primary immiscibility between two melts and a fluid during anatexis. The production of both carbonatitic and granitic melts during the same anatectic event requires a suitable heterogeneous protolith. This may be represented by a sedimentary sequence containing marble lenses of limited extension, similar to the one still visible in the adjacent central Moldanubian Zone. The presence of CO2-rich fluid inclusions suggests furthermore that high CO2 activity during anatexis may be required to stabilize a carbonate-rich melt in a silica-dominated system. This natural occurrence displays a remarkable similarity with experiments on carbonate-silicate melt immiscibility, where CO2 saturation is a condition commonly imposed.
DS201711-2511
2017
O'Brien, P.J.Ferrerro, S.., Wunder, B., Ziemann, M.A., Walle, M., O'Brien, P.J.Carbonatitic and granitic melts produced under conditions of primary immiscibility during anatexis in the lower crust.Earth and Planetary Science Letters, Vol. 454, pp. 121-131.Mantlecarbonatites

Abstract: Carbonatites are peculiar magmatic rocks with mantle-related genesis, commonly interpreted as the products of melting of CO2-bearing peridotites, or resulting from the chemical evolution of mantle-derived magmas, either through extreme differentiation or secondary immiscibility. Here we report the first finding of anatectic carbonatites of crustal origin, preserved as calcite-rich polycrystalline inclusions in garnet from low-to-medium pressure migmatites of the Oberpfalz area, SW Bohemian Massif (Central Europe). These inclusions originally trapped a melt of calciocarbonatitic composition with a characteristic enrichment in Ba, Sr and LREE. This interpretation is supported by the results of a detailed microstructural and microchemical investigation, as well as re-melting experiments using a piston cylinder apparatus. Carbonatitic inclusions coexist in the same cluster with crystallized silicate melt inclusions (nanogranites) and COH fluid inclusions, suggesting conditions of primary immiscibility between two melts and a fluid during anatexis. The production of both carbonatitic and granitic melts during the same anatectic event requires a suitable heterogeneous protolith. This may be represented by a sedimentary sequence containing marble lenses of limited extension, similar to the one still visible in the adjacent central Moldanubian Zone. The presence of CO2-rich fluid inclusions suggests furthermore that high CO2 activity during anatexis may be required to stabilize a carbonate-rich melt in a silica-dominated system. This natural occurrence displays a remarkable similarity with experiments on carbonate-silicate melt immiscibility, where CO2 saturation is a condition commonly imposed. In conclusion, this study shows how the investigation of partial melting through melt inclusion studies may unveil unexpected processes whose evidence, while preserved in stiff minerals such as garnet, is completely obliterated in the rest of the rock due to metamorphic re-equilibration. Our results thus provide invaluable new insights into the processes which shape the geochemical evolution of our planet, such as the redistribution of carbon and strategic metals during orogenesis.
DS1982-0477
1982
O'brien, T.F.O'brien, T.F., Kay, S.M.Rare Earth Elements (ree) and Trace Elements in Basic Lower Crustal XenolithsGeological Society of America (GSA), Vol. 14, No. 7, P. 578, (abstract.).GlobalGeochemistry
DS1983-0487
1983
O'brien, T.F.O'brien, T.F.Evidence for the Nature of the Lower Crust Beneath the Central Colorado Plateau As Derived from Xenoliths in the Buell Park Green Knobs Diatremes.Ph.d. Thesis, Cornell University, United States, Arizona, New Mexico, Colorado PlateauLower Crust Composition
DS1989-1145
1989
O'Brien, W.O'Brien, W.Interactive Over thrust interpretationGeophysics: the leading edge of exploration, Vol. 8, No. 4, April pp. 24-28. Database # 17767Rocky MountainsGeophysics, Seismics
DS200712-0886
2007
Obst, K.Rehfeldt, T., Obst, K., Johannson, L.Petrogenesis of ultramafic and mafic xenoliths from Mesozoic basanites in southern Sweden: constraints from mineral chemistry.International Journal of Earth Sciences, Vol. 96, 3, pp. 433-450.Europe, SwedenBasanites, Foidites
DS200712-0887
2007
Obst, K.Rehfeldt, T., Obst, K., Johansson, L.Petrogenesis of ultramafic and mafic xenoliths from Mesozoic basanites in southern Sweden: constraints from mineral chemistry.International Journal of Earth Sciences, Vol. 96, 3, pp. 433-450.Europe, SwedenBasanites, Foidites
DS1990-1533
1990
Obuch, R.C.Wandrey, C.J., Obuch, R.C.FORMATIONTOPS (version 1): a system to retrieve formation tops dataUnited States Geological Survey (USGS) Open File, No. 90-0530, 1 disc. $ 6.00GlobalComputer, Program -FORMATIONTOPS
DS201112-0751
2011
Obuchi, T.Obuchi, T., Karato, S-I., Fujino, K.Strength of single crystal orthopyroxene under lithospheric conditions.Contributions to Mineralogy and Petrology, Vol. 161, pp. 961-975.MantleConvection
DS201312-0661
2013
Obuchi, T.Obuchi, T., Irifune, T.Development of A type olivine fabric in water rich deep upper mantle.Earth and Planetary Science Letters, Vol. 362, pp. 20-30.MantleSeismic anisotropy
DS201802-0260
2018
Obukhov, A.V.Prokopyev, I.R., Doroshkevich, A.G., Redina, A.A., Obukhov, A.V.Magnetite apatite dolomitic rocks of Ust Chulman ( Aldan Shield, Russia): Seligdar type carbonatites?Mineralogy and Petrology, in press available, 10p.Russia, Aldan shieldcarbonatites

Abstract: The Ust-Chulman apatite ore body is situated within the Nimnyrskaya apatite zone at the Aldan shield in Russia. The latest data confirm the carbonatitic origin of the Seligdar apatite deposit (Prokopyev et al. in Ore Geol Rev 81:296-308, 2017). The results of our investigations demonstrate that the magnetite-apatite-dolomitic rocks of the Ust-Chulman are highly similar to Seligdar-type dolomitic carbonatites in terms of the mineralogy and the fluid regime of formation. The ilmenite and spinel mineral phases occur as solid solutions with magnetite, and support the magmatic origin of the Ust-Chulman ores. The chemical composition of REE- and SO3-bearing apatite crystals and, specifically, monazite-(Ce) mineralisation and the formation of Nb-rutile, late hydrothermal sulphate minerals (barite, anhydrite) and haematite are typical for carbonatite complexes. The fluid inclusions study revealed similarities to the evolutionary trend of the Seligdar carbonatites that included changes of the hydrothermal solutions from highly concentrated chloride to medium-low concentrated chloride-sulphate and oxidized carbonate-ferrous.
DS2002-0988
2002
ObydenMakeev, A.B., Ivanuch, Obyden, Saparin, FilippovMineralogy, composition of inclusions and cathodluminescence of carbonado from Bahia State.Geology of Ore Deposits, Vol.44,2,pp.87-102.Brazil, BahiaMineralogy, geochronology, Carbonado
DS2002-1597
2002
Obyden, C.K.Titkov, S.V., Saparin, G.V., Obyden, C.K.A study of the evolution of grwoth sectors in natural diamond crystals using cathodluminescence microscopy.18th. International Mineralogical Association Sept. 1-6, Edinburgh, abstract p.151.RussiaDiamond - crystallography
DS1990-1623
1990
Obyden, S.K.Zezin, R.B., Saparin, G.V., Smirnova, E.P., Obyden, S.K., ChukichevCathodluminescence of natural diamonds from Jakutian depositsScanning, Vol. 12, No.6, Nov-Dec. pp. 326-333RussiaDiamond morphology, Cathodluminescence
DS1992-1733
1992
Obyden, S.K.Zezin, R.B., Smirnova, E.P., Saparin, G.V., Obyden, S.K.New growth features of natural diamonds, revealed by colour cathodluminescence scanning electron microscope (CCL SEM) techniqueScanning, Vol. 14, No. 1, Jan-Feb. pp. 3-10.# HC 517GlobalNatural diamond morphology, Cathodluminescence
DS1998-1284
1998
Obyden, S.K.Saparin, G.V., Obyden, S.K., Titkov, S.V.Use of cathodluminescence scanning electron microscope (SEM) with color TVdisplay for study natural diamonds -7th. Kimberlite Conference abstract, pp. 763-5.Russia, YakutiaDiamond morphology - structure, Luminescence - CL-scanning electron microscope (SEM).
DS2002-1598
2002
Obyden, S.K.Titkov, S.V., Saparin, G.V., Obyden, S.K.Evolution of growth sectors in natural diamond crystals as revealed by cathodluminescence topography.Geology of Ore Deposits, Vol. 44, 5, pp. 350-63.GlobalDiamond morphology
DS2002-1666
2002
Obyden, S.K.Viktorov, M.A., Shelementiev, Yu.B., Saparin, G.V., Obyden, S.K., ChhukichevSpectroscopic properties of artifically coloured diamonds18th. International Mineralogical Association Sept. 1-6, Edinburgh, abstract p.149.GlobalDiamond - colouration
DS200412-1208
2003
Obyden, S.K.Makeyev, A.B., Iwanuch, W., Obyden, S.K., Bryachaninova, N.I., Saparin, G.V.Inter relation of diamond and carbonado ( based on study of collections from Brazil and Middle Timan).Doklady Earth Sciences, Vol. 393a, no. 9, pp.1251-5.Russia, South America, BrazilDiamond morphology
DS1984-0564
1984
O'callaghan, D.O'callaghan, D.Kimberlite Indications of Diamonds on the Wintinna PropertyCity of London Public Relations Limited., 1P.Australia, South AustraliaProspecting, Sampling, Drill Core
DS2003-1026
2003
Occelli, F.Occelli, F., Loubeyre, P., LeToullec, R.Properties of diamond under hydrostatic pressures up to 140 GPaNature Materials, Vol. 2,3,pp. 151-54.GlobalDiamond morphology
DS201610-1884
2016
Occhipinti, S.Lindsay, M., Spratt, J., Occhipinti, S., Aitken, A., Dentith, M., Metelka, V., Hollis, J., Tyler, I.Integrated interpretation of magnetotelluric and potential field data: assessing the northeast Kimberley region. ( no mention of kimberlites)ASEG-PESA-AIG 2016 25th Geophysical Conference, Abstract 4p.AustraliaGeophysics
DS201904-0763
2019
Occipinti, S.A.Olierook, H.K.H., Agangi, A., Plavsa, D., Reddy, S.M., Yao, W., Clark, C., Occipinti, S.A., Kylander-Clark, A.R.C.Neoproterozoic hydrothermal activity in the west Australian craton related to Rodinia assembly or breakup?Gondwana Research, Vol 68, 1, pp. 1-12.Australiacraton

Abstract: The timing of final assembly and initiation of subsequent rifting of Rodinia is disputed. New rutile ages (913?±?9?Ma, 900?±?8?Ma and 873?±?3?Ma) and published zircon, monazite, titanite, biotite, muscovite and xenotime geochronology from the Capricorn Orogen (West Australian Craton) reveal a significant early Neoproterozoic event characterized by very low to low metamorphic grade, abundant metasomatism, minor leucogranitic and pegmatitic magmatism and NW-SE fault reactivation episodes between ca. 955 and 830?Ma. Collectively, these are termed the ca. 955-830?Ma Kuparr Tectonic Event. An age range of ca. 955-830?Ma is concomitant with the final stages of Rodinia assembly and the initial stages of its attempted breakup. Very low- to low-grade metamorphic and structural geological evidence favor a distal north-south compressional regime as the driver for hydrothermal activity during ca. 955-830?Ma. Nearby continental collision or accretion from the west (e.g., South China and/or Tarim) are ruled out. The cessation of metasomatism and magmatism in the West Australian Craton after ca. 830?Ma is concomitant with the emplacement of the Gairdner-Amata dyke swarm and associated magmatic activity in South China and Laurentia, the inception of the Adelaide Rift Complex and the deposition of the Centralian Superbasin. We posit that the cessation of hydrothermal activity in the Capricorn Orogen was caused by a tectonic switch from compressional to extensional at ca. 830?Ma. Magmatic and hydrothermal fluids were transferred away from the Capricorn Orogen to the incipient Adelaide Rift Complex, terminating metasomatism in the West Australian Craton. Ultimately, the Kuparr Tectonic Event marked the final stages of Rodinia assembly and its cessation marks the initial stages of its attempted breakup.
DS1996-1047
1996
OceanologyOceanologyMajor South African diamond miner joins Sundra shelf project..Oceanology, Vol. 1, No. 1, 2p.OceansMarine mining, Ocean Resources, Trans Hex
DS2002-1785
2002
Ochi, F.Zhao, D., Ochi, F., Takahashi, E.Seismic images of hot spots and mantle plumesGeophysics Monograph, American geophysical Union, No. 128, pp. 349-64.MantleGeophysics - seismics
DS200812-0350
2008
Ochika, F.Filhio, J.P.D., Oliviera, E., Pisani, J.R., Ochika, F.Geochemistry and mineralogy of kimberlites from the Brauna kimberlite province, Sao Francisco Craton, NE Brazil.9IKC.com, 3p. extended abstractSouth America, BrazilDeposit - Brauna field
DS201811-2596
2015
Ochoa, C.J.C.Ochoa, C.J.C., Herreno Daza, M.J., Fortaleche, D., Jimenez, J.F.Progress on the study of parameters related to the origin of Colombian diamonds.InColor, December pp. 88-97.South America, Colombiaemeralds
DS1900-0347
1905
Ochs, L.Ochs, L.Afrique du Sud. les Mines de DiamantsMonit. Off. Commer. Ind., Vol. 44, MARCH 2ND. PP. 187-192.Africa, South AfricaCurrent Activities
DS1930-0141
1933
Ockepan, J.W.Landes, K.R., Ockepan, J.W.Origin of Domes in Lincoln and Mitchell Counties, KansasGeological Society of America (GSA) Bulletin., Vol. 44, No. 3, PP. 529-540.KansasKimberlite, Central States, Wilson, Woodson
DS1970-0162
1970
Ocola, L.C.Ocola, L.C.Evidence Relative to the Origin of the Midcontinent Region And its Mineral Deposits.Eos, Vol. 51, No. 4, P. 357, (abstract.).GlobalMid-continent
DS1970-0163
1970
Ocola, L.C.Ocola, L.C., Meyer, R.P.Regional Upper Crustal Structure of Midcontinent of the U.s.a.Geological Society of America (GSA), Vol. 2, No. 7, P. 638. (abstract.)GlobalMid-continent
DS1970-0164
1970
Ocola, L.C.Ocola, L.C., Meyer, R.P.Regional Crustal Structure of Mid-continent of the United States (us)Earthquake Notes, Vol. 41, No. 4, P. 18. (abstract.).GlobalMid-continent
DS1970-0798
1973
Ocola, L.C.Ocola, L.C., Meyer, R.P.The Central North American Rift SystemTectonophysics, Vol. 20, P. 215. (abstract.).GlobalMid-continent
DS1970-0799
1973
Ocola, L.C.Ocola, L.C., Meyer, R.P.Central North American Rift System Pt. 1: Structure of The axial Zone from Seismic and Gravimetric Data.Journal of GEOPHYSICAL RESEARCH, Vol. 78, PP. 5173-5184.GlobalMid-continent Geophysics
DS1991-1835
1991
O'Connell, R.J.Wdowinski, S., O'Connell, R.J.Deformation of the central Andes ( 15 - 27 S) derived from a flow model of subduction zones.Journal of Geophysical Research, Vol. 96, No. B7, July 10, pp. 12, 245-55.AndesTectonics - subduction
DS1992-0989
1992
O'Connell, R.J.Manga, M., O'Connell, R.J., Stone, H.A.Effect of boundaries and compositional layering in the mantle on the ascent of mantle plumesEos Transactions, Vol. 73, No. 14, April 7, supplement abstracts p. 297MantlePlumes
DS1992-1132
1992
O'Connell, R.J.O'Connell, R.J., Gable, C.W.Some relations between plate motions and mantle convectionEos Transactions, Vol. 73, No. 14, April 7, supplement abstracts p. 272MantleMantle convection, Tectonics
DS1992-1518
1992
O'Connell, R.J.Tao, W.C., O'Connell, R.J.Ablative subduction: a two sided alternative to the conventional subductionmodelJournal of Geophysical Research, Vol. 97, No. B6, June 10, pp. 8877-8904GlobalSubduction, Plate tectonics
DS1993-1571
1993
O'Connell, R.J.Tao, W.C., O'Connell, R.J.Deformation of a weak subducted slab and variation of seismicity at depthNature, Vol. 361, No. 6413, February 18, pp. 626-628GlobalTectonics, Mantle, Geophysics -seismics
DS1995-0552
1995
O'Connell, R.J.Forte, A.M., Dziewonski, A.M., O'Connell, R.J.Continent ocean chemical heterogeneity in the mantle based on seismictomography.Science, Vol. 268, April 21, pp. 386-388.MantleGeodynamic, Geophysics -seismics
DS1995-1372
1995
O'Connell, R.J.O'Connell, R.J.Mantle flow, viscosity structure and geochemical reservoirsEos, Vol. 76, No. 46, Nov. 7. p.F605. Abstract.MantleGeodynamics, Tomography
DS1998-1266
1998
O'Connell, R.J.Rudnick, R.L., McDonough, W.F., O'Connell, R.J.Thermal structure, thickness and composition of continental lithosphereChemical Geology, Vol. 145, No. 3-4, Apr. 15, pp. 395-412.MantleTectonics
DS2002-1550
2002
O'Connell, R.J.Steinberger, B., O'Connell, R.J.The convective mantle flow signal rates of True Polar WanderAmerican Geophysical Union, Geodynamics Series, Vol. 29, pp. 233-56.MantleGeophysics - seismics
DS200412-0894
2004
O'Connell, R.J.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
DS200412-1457
2004
O'Connell, R.J.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
DS200412-1924
2002
O'Connell, R.J.Steinberger, B., O'Connell, R.J.The convective mantle flow signal rates of True Polar Wander.American Geophysical Union, Geodynamics Series, Vol. 29, pp. 233-56.MantleGeophysics - seismics
DS200612-0110
2006
O'Connell, R.J.Becker, T.W., Schulte-Pelkum, V., Blackman, D.K., Kellogg, J.B., O'Connell, R.J.Mantle flow under the western United States from shear wave splitting.Earth and Planetary Science Letters, in press availableUnited StatesGeophysics - seismics, tectonics, convection
DS200912-0784
2009
O'Connell, R.J.Valencia, D., O'Connell, R.J.Convection scaling and subduction on Earth and super-Earths.Earth and Planetary Science Letters, Vol. 286, 3-4, pp. 492-502.MantleConvection
DS1989-0210
1989
O'Connell, S.Cant, D., O'Connell, S.The Peace River Arch: its structure and originCan. Soc. Pet. Geol., Sequences, stratigraphy, sedimentology:surface and, Memoir No. 15, pp. 537-542AlbertaStructure
DS1990-1126
1990
O'Connell, S.C.O'Connell, S.C., Dix, G.R., Barclay, J.E.The origin, history and regional structural developments of the Peace RiverArch, western CanadaGeology of the Peace River Arch, ed. Sc.C. O'Connell, J.S. Bell, Bulletin. Can., Vol. 38A, Special Volume, December pp. 4-24AlbertaPeace River area, Tectonics, structure
DS1982-0478
1982
O'connor, D.O'connor, D., Geopeko ltd.El 3146 Final Report 19/10/81 to 17/6/82Northern Territory Open File., No. CR 82-272, 10P. 1 MAP UNPUBL.Australia, Northern TerritoryDiamonds, Geochemistry, Geophysics, Stream Sediment Sampling
DS1982-0479
1982
O'connor, G.O'connor, G.Go the Hole Hog and Taste Our Rich Diamond Studed PastThe Kimberley Star., DECEMBER 1ST. PP. 16-17.South AfricaMuseum
DS1995-1259
1995
O'Connor, J.M.Milner, S.C., Le Roex, A.P., O'Connor, J.M.Age of Mesozoic igneous rocks in northwestern Namibia and their relationship to continental breakupJournal of the Geological Society of London, Vol. 152, No. 1, Jan. pp. 97-104NamibiaTectonics, Geochronology
DS2002-1170
2002
O'Connor, J.M.O'Connor, J.M., Stoffer, P., Wijbrans, J.R.Pulsing of a focused mantle plume. Evidence from the distribution of Foundation Chain hotspot volcanism.Geophysical Research Letters, Vol. 29,9,May 1, p. 64-GlobalMantle plumes - not specific to diamonds
DS1994-1293
1994
O'Connor, P.J.O'Connor, P.J., Hogelsberger, H., Feely, M., Rex, D.C.Fluid inclusion studies, rare-earth element chemistry and age of hydrothermal fluid mineralization in w Ireland- link continental rifting?Institute of Mining and Metallurgy (IMM) Bulletins, Vol. 102, pp. B141-B148IrelandGeochemistry, Geochronology
DS1990-1127
1990
O'Connor, T.K.O'Connor, T.K., MacRae, N.D.A new occurrence of Rhoenite in a lherzolite xenolithof Victoria, AustraliaGeological Association of Canada (GAC)/Mineralogical Association of Canada (MAC) Vancouver 90 Program with Abstracts, Held May 16-18, Vol. 15, p. A98. AbstractAustraliaMt. Leura, Lherzolite xenolith
DS1996-1048
1996
O'Connor, T.K.O'Connor, T.K., Edgar, A.D., Lloyd, F.E.Origin of glass in Quaternary mantle xenoliths from Meerfeldmaar West EifelGermany: implications mantleCanadian Mineralogist, Vol. 34, pt. 2, April pp. 187-200.GermanyLithospher -mantle, Xenoliths
DS201112-1156
2011
OdakeZedgenizov, D.A., Ragozin, Shatsky, Kagi, Odake, Griffin, Araujo, YuryevaEvidence for evolution of growth media in superdeep diamonds from Sao-Luis Brazil.Goldschmidt Conference 2011, abstract p.2244.South America, BrazilCl imaging
DS200712-0158
2007
Odake, S.Cayzer, N.J., Odake, S., Harte, B., Kagi, H.Plastic deformation of lower mantle diamonds by inclusion phases transformations.Frontiers in Mineral Sciences 2007, Joint Meeting of Mineralogical societies Held June 26-28, Cambridge, Abstract Volume p.188-189.MantleDiamond morphology
DS200712-0159
2007
Odake, S.Cayzer, N.J., Odake, S., Harte, B., Kagi, H.Plastic deformation of lower mantle diamonds by inclusion phases transformations.Frontiers in Mineral Sciences 2007, Joint Meeting of Mineralogical societies Held June 26-28, Cambridge, Abstract Volume p.188-189.MantleDiamond morphology
DS200812-0189
2008
Odake, S.Cayzer, N.J., Odake, S., Harte, B., Kagi, H.Plastic deformation of lower mantle diamonds by inclusion phase transformation.European Journal of Mineralogy, Vol. 20, no. 3, 333-339.MantleDiamond inclusions
DS200912-0349
2008
Odake, S.Kagi, H., Odake, S., Zedgenizov, D.Depth of diamonds formation: a novel spectroscopic approach to the 3-D mapping of stress patterns.American Geological Union, Fall meeting Dec. 15-19, Eos Trans. Vol. 89, no. 53, meeting supplement, 1p. abstractMantleUHP
DS200912-0544
2009
Odake, S.Odake, S., Fukura, S., Arakawa, S., Ohta, M., Harte, B., Kagi, H.Divalent chromium in ferropericlase inclusions in lower mantle diamonds revealed by morco XANES measurements.Journal of Mineralogical and Petrological Sciences, Vol. 103, 5, pp. 350-353.TechnologyDiamond inclusions
DS200912-0545
2009
Odake, S.Odake, S., Kagi, H., Arakawa, M., Ohta, A., Harte, B.Oxidation state of chromium in ferropericlese inclusions in lower mantle diamonds determined with micro-XANES measurements.Goldschmidt Conference 2009, p. A962 Abstract.MantleDiamond inclusions
DS201012-0332
2009
Odake, S.Kagi, H., Odake, S., Fukura, S., Zedgenizov, D.A.Raman spectroscopic estimation of depth of diamond origin: technical developments and the application.Russian Geology and Geophysics, Vol. 50, 12, pp. 1183-1187.TechnologyDiamond genesis
DS201901-0049
2018
Odake, S.Odake, S.Melee diamonds: metal defects and treated color.Gems & Gemology, Sixth International Gemological Symposium Vol. 54, 3, 1p. Abstract p. 304.Globaldiamond color

Abstract: Gem-quality laboratory-grown diamonds are manufactured in large quantities. With frequent reports of the mixing of meleesized synthetic diamonds with natural stones, demand for melee diamond screening is increasing. During melee diamond screening at GIA’s Tokyo lab, two notable types of samples with uncommon characteristics have been found. 1. Natural melee diamonds with silicon and nickel defects. Luminescence peaks derived from Si- and Ni-related defects are often observed in colorless melee grown by the HPHT method. The silicon-related defect, once considered proof of CVD-grown diamond, is now known to exist naturally as well (Breeding and Wang, 2008). Several colorless melee diamonds having both silicon- and nickel-related emissions have been found in GIA’s Tokyo lab; olivine inclusions were found in one of these samples. Spectroscopic and gemological features confirmed that the samples were grown in nature. 2. Irradiated laboratory-grown diamond melee found among irradiated natural melee diamonds. Several thousand greenish blue melee diamonds have been submitted by various clients to the Tokyo lab for testing. Each diamond’s color was attributed to a strong GR1 defect caused by irradiation treatment. Fourier-transform infrared (FTIR), photoluminescence (PL), and DiamondView analysis revealed that most of them were irradiated natural diamonds. Eight were irradiated CVD-grown diamonds, and one was an irradiated HPHT-grown specimen. The infrared spectrum of all the CVD samples showed a peak at 3123 cm-1, while their PL spectrum showed a doublet peak at 596/597 nm. Those peaks are specific to as-grown CVD diamonds, as annealing removes the peaks. From their spectra, these CVD specimens were considered irradiated without pre-annealing.
DS200912-0456
2009
Odaki, T.Lu, T., Odaki, T., Yasunaga, K., Uesugi, H.A fancy reddish brown diamond with new optical absorption features.Journal of Gemmology, Vol. 31, 2-4, pp. 73-76.TechnologyDiamond colour
DS1930-0034
1930
O'daniel, H.O'daniel, H.Ein Chromhaltiger Pyroxen von JagersfonteinZeitschr. Kryst. (leipzig), Vol. 75, P. 575.South Africa, Cape Province, Kimberley AreaPyroxene, Chomite, Mineralogy, Petrography
DS1990-1475
1990
Oddone, M.Toscani, L., Capedri, I.S., Oddone, M.New chemical and petrographic dat a of some undersaturated lavas from Nyiragongo and Mikeno (Virunga Western African rift- Zaire)Neues Jahrbuch fnr Mineralogie, Vol. 161, No. 3, May pp. 287-302Democratic Republic of CongoChemistry -lavas, Petrography
DS201112-0903
2011
Oddone, M.Salvioli-Mariani, E., Toscani, L., Bersani, D., Oddone, M., Cancelliere, R.Late veins of C3 carbonatite intrusion from Jacupiranga complex ( southern Brazil): fluid and melt inclusions and mineralogy.Mineralogy and Petrology, In press available,South America, BrazilCarbonatite
DS201212-0618
2012
Oddone, M.Salvioli-Mariani, E., Toscani, L., Bersani, D., Oddone, M., Cancellielere, R.Late veins of C 3 carbonatite intrusion from Jacupiranga complex, southern Brazil: fluid and melt inclusions and mineralogy.Mineralogy and Petrology, Vol. 104, 1-2, pp. 95-114.South America, BrazilCarbonatite
DS1997-0862
1997
O'Dea, M.G.O'Dea, M.G., Lister, G.S., Betts, P.G., Pound, K.S.A shortened intraplate rift system in the Proterozoic Mount Isa terrane, northwestQueensland, AustraliaTectonics, Vol. 16, No. 3, June, pp. 425-441AustraliaProterozoic
DS1998-0121
1998
O'Dea, M.G.Betts, P.G., Lister, G.S., O'Dea, M.G.Asymmetric extension of the Middle Proterozoic lithosphere, Mount Isaterrane, Queensland.Tectonophysics, Vol. 296, No. 3-4, Nov. 10, pp. 293-316.AustraliaTectonic, Deposit - Mount Isa area
DS1991-0684
1991
Oderkirk, J.R.Hausen, D.M., Oderkirk, J.R.XRD mineralogic logging of drill samples from gold and copper miningoperationsOre Geology Reviews, Special issue -Applied mineralogy in exploration, Vol. 6, No. 2-3, May pp. 107-118NevadaSampling -logging, XRD.
DS1988-0515
1988
Odermatt, W.Odermatt, W.Spin dynamics of transitions among muon states in semiconductorsHelv. Phys. Acta, Vol. 61, No. 8, pp. 1087-1129GlobalDiamond morphology, MuoniuM.
DS1988-0516
1988
Odermatt, W.Odermatt, W., Baumeler, H., Keller, H., Kuendig, W., PattersonSign of hyperfine parameters of anomalous muonium in diamondPhys. Rev. B., Condensed Matter, Vol. 38, No. 7, pp. 4388-4393GlobalDiamond morphology, MuoniuM.
DS1993-1155
1993
Odgers, A.T.R.Odgers, A.T.R., Hinds, R.C., Von Gruenewaldt, G.Interpretation of a seismic reflection survey across the southern BushveldComplexSouth African Journal of Geology, Vol. 96, No. 4, pp. 205-212South AfricaGeophysics -seismics, Deposit -Bushveld
DS201610-1869
2016
Oding, W.A.Hastie, A.R., Fitton, J.G., Bromiley, G.D., Butler, I.B., Oding, W.A.The origin of Earth's first continents and the onset of plate tectonics.Geology, Vol. 44, 10, pp. 855-858.MantleSubduction

Abstract: The growth and recycling of continental crust has resulted in the chemical and thermal modification of Earth's mantle, hydrosphere, atmosphere, and biosphere for ~4.0 b.y. However, knowledge of the protolith that gave rise to the first continents and whether the environment of formation was a subduction zone still remains unknown. Here, tonalite melts are formed in high P-T experiments in which primitive oceanic plateau starting material is used as an analogue for Eoarchean (3.6-4.0 Ga) oceanic crust generated at early spreading centers. The tonalites are produced at 1.6-2.2 GPa and 900-950 °C and are mixed with slab-derived aqueous fluids to generate melts that have compositions identical to that of Eoarchean continental crust. Our data support the idea that the first continents formed at ca. 4 Ga and subsequently, through the subduction and partial melting of ~30-45-km-thick Eoarchean oceanic crust, modified Earth's mantle and Eoarchean environments and ecosystems.
DS1960-0284
1962
Odintsov, M.M.Odintsov, M.M., et al.Structure Volcanic Activity and Diamonds of the Irkutsk Amphitheater.Akad. Nauk Sssr Izv. Geol. Series, RussiaKimberlite
DS1960-0285
1962
Odintsov, M.M.Odintsov, M.M., Tverdokhlebov, V.A., Vladimirov, B.M., Ilyukhi.Structure, Volcanism and Diamondiferous Deposits in the Irkutsk Amphitheatre.Moscow: Izdat Nauka., 179P.Russia, IrkutskKimberlite, Kimberley
DS1960-0722
1966
Odintsov, M.M.Odintsov, M.M., Vladimirov, B.M.Some General Regularities of Spacial Distribution of Kimberlites and Diamond Bearing Occurrences in the Earth's Crust.In: Problems of Genesis And Regularities of Distribution Of, MOSCOW: NEDRA.RussiaBlank
DS1960-1004
1968
Odintsov, M.M.Odintsov, M.M., Strakhov, L.G.Trap and Kimberlite Pipes As an Index of Features of Structural Development of the Continental Crust of Ancient Platforms.In: Volcanism And Tectogenesis. Moscow: Nauka., PP.165-173.RussiaBlank
DS1960-1005
1968
Odintsov, M.M.Odintsov, M.M., Vladimirov, B.M., Tverdokhledeboy, I.Regularities of Kimberlite Distribution in the Earth's CrustInternational Geological Congress 23RD., PP. 139-146.RussiaBlank
DS1981-0319
1981
Odintsov, M.M.Odintsov, M.M., Pavlov, S.F.The Clssification of Kimberlites and the Internal Structure of Kimberlite Pipes.Moscow: Izd. Nauka., 138P.RussiaBlank
DS201312-0928
2013
Odling, N.Upton, B.G.J., Macdonald, R., Odling, N., Ramo, O.T., Baginski, B.Kungnaat, revisited. A review of five decades of research into an alkaline complex in South Greenland, with new trace element and Nd isotopic data.Mineralogical Magazine, Vol. 77, 4, pp. 523-550.Europe, GreenlandKungnaat
DS1990-0660
1990
Odling, N.W.A.Harley, S.L., Odling, N.W.A.Mantle geochemistry: reducing mantle redox optionsNature, Vol. 348, No. 6300, November 29, pp. 394-395GlobalMantle, Geochemistry
DS1990-1128
1990
Odling, N.W.A.Odling, N.W.A., Mernagh, T., Green, D.H.high pressure, high temperature fluid inclusion synthesis: analysis andimplicationsTerra, Abstracts of Experimental mineralogy, petrology and, Vol. 2, December abstracts p. 89GlobalMantle, Xenoliths
DS1994-1294
1994
Odling, N.W.A.Odling, N.W.A.An experimental simulation of upper mantle MetasomatismAmerican Mineralogist, Vol. 79, No. 1-2, January-February, pp. 148-153.MantleMetasomatism
DS1995-1373
1995
Odling, N.W.A.Odling, N.W.A.An experimental replication of upper mantle MetasomatismNature, Vol. 373, No. 6509, Jan. 5, pp. 58-60.MantleMetasomatism
DS1950-0347
1957
Odman, O.H.Odman, O.H.Beskrivning Till Berggrundskarta Over Urberget I Norrbottens Lan.Sver. Geol. Undersokn., SER. CA, No. 41, PP. 108-109; 128; 147.Norway, ScandinaviaBlank
DS1983-0529
1983
Odom, A.Rankin, D.W., Stern, T.W., Mclelland, J., Zartman, R.E., Odom, A.Correlation Chart for Precambrian Rocks of the Eastern United States.United States Geological Survey (USGS) PROF. PAPER., No. 1241-E, 18P.GlobalMid-continent
DS1982-0480
1982
O'donaghue, M.O'donaghue, M.Minerals and GemstonesVan Nostrand., 159P.GlobalMineralogy, Kimberley
DS201312-0662
2013
Odonnell, J.P.Odonnell, J.P., Adams, A., Nyblade, A.A., Mulibo, G.D., Tugume, F.The uppermost mantle shear wave velocty structure of eastern Africa from Rayleigh wave tomography: constraints on rift evolution.Geophysical Journal International, Vol. 194, 2, pp. 961-978.AfricaGeophysics - seismics
DS1995-0740
1995
O'Donnell, J.Haner, B., O'Donnell, J.Changing gateways: the impact of technology on Geoscience informationexchangeProceedings 29th. GIS Volume, No. 25, 120pUnited StatesBook -information technology, Table of contents
DS201909-2083
2019
O'Donnell, J.P.Selway, K., O'Donnell, J.P., Ozaydin, S.Upper mantle melt distribution from petrologically constrained magnetotellurics.Geochemistry, Geophysics, Geosystems, Vol. 20, 7, pp. 3328-3346.Mantlemelting

Abstract: Plate tectonics occurs because the strong tectonic plates sit on underlying weaker and softer mantle that flows over geological timescales. We do not fully understand why this deeper mantle is weak—the two main contenders are that a small part of it is molten or that it contains nominal amounts of the element hydrogen. The electrical conductivity of the mantle is increased both by the presence of molten rock and by hydrogen, so when we interpret conductivity data, it is difficult to distinguish between these two interpretations. We have written a new code to help this. It analyzes whether the conductivity of the mantle could only be explained by the presence of molten rock, whether it could only be explained by large hydrogen contents, or whether it could be explained by either. Our results show that the distribution of partially molten rock is very uneven: Most lies beneath hot spot volcanic islands, while there is no need for molten rock to be present beneath old continents or old parts of the ocean. Beneath young parts of the ocean, the electrical conductivities could be explained by either a small amount of molten rock or by large hydrogen contents.
DS1970-0375
1971
O'dowd, M.C.O'dowd, M.C.The Second Source. Grahamstown 1820 SettlersNational Mon. Foundation., 23P.South AfricaHistory
DS1991-1248
1991
O'Dowd, R.J.O'Dowd, R.J.Conditions of coefficient matrices of ordinary krigingMathematical Geology, Vol. 23, No. 5, July pp. 721-740GlobalGeostatistics, Kriging
DS201412-0130
2014
O'Driscoll, B.Clay, P.L., O'Driscoll, B., Upton, B.G.J., Busemann, H.Characteristics of djerfisherite from fluid rich metasomatized alkaline intrusive environments and anhydrous enstatite chrondrites and achondrites.American Mineralogist, Vol. 99, pp. 1683-93.MantleDjerfisherites
DS201807-1510
2018
O'Driscoll, B.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.
DS1986-0616
1986
O'Driscoll, E.S.T.O'Driscoll, E.S.T.Observations of the lineament ore relationRoyal Soc. London Phil. TRans, Series A. No. 317, pp. 195-218GlobalStructure, Tectonics
DS1995-1374
1995
O'Driscoll, E.S.T.O'Driscoll, E.S.T., Campbell, I.B.Ore deposits related to Australian continental rifts and ring structuresIagod Giant Ore Deposits Workshop, J. Kutina, 9p.AustraliaTectonics, Lineaments, ring structures -not specific to diamonds
DS1997-0863
1997
O'Driscoll, E.S.T.O'Driscoll, E.S.T., Campbell, I.B.Mineral deposits related to Australian continental ring and rift structures with some terrestrial analogiesGlobal Tectonics and Metallogeny, Vol. 6, No. 2, March pp. 83-102AustraliaMetallogeny, model, Deposits - ring, rift complexes
DS200912-0546
2009
O'Driscoll, L.J.O'Driscoll, L.J., Humphreys, E.D., Saucier, F.Subduction adjacent to deep continental roots: enhanced negative pressure in the mantle wedge, mountain building and continental motion.Earth and Planetary Science Letters, Vol. 280, 1-4, Apr. 15, pp. 61-70.MantleSubduction
DS1988-0517
1988
O'Driscoll, M.O'Driscoll, M.Rare earths: enter the dragonIndustrial Minerals, No. 254, November pp. 21-55. Database # 17552ChinaRare earths, Review - economics
DS1992-1133
1992
O'Driscoll, M.O'Driscoll, M.Garnet: set for a blast off?Industrial Minerals, December pp. 22-33 odd pagesGlobalEconomics, Garnet
DS1994-1295
1994
O'Driscoll, M.O'Driscoll, M.China's minerals industry... gathering for the great leap forwardIndustrial Minerals, June pp. 19-57ChinaEconomics, Mineral industry
DS1994-1296
1994
O'Driscoll, M.O'Driscoll, M.China's minerals industry... gathering for the great leap forwardIndustrial Minerals, June pp. 19-57.ChinaEconomics, Mineral industry -general
DS1997-0864
1997
O'Driscoll, M.O'Driscoll, M.Silicon carbide : supply sector showdownIndustrial Minerals, Jan. pp. 19-24.GlobalEconomics, Silicon carbide, SIC.
DS1997-0865
1997
O'Driscoll, M.O'Driscoll, M.Silicon carbide: supply sector slowdownIndustrial Minerals, Jan. pp. 19-24GlobalSIC, silicon carbide, Economics
DS201012-0753
2010
O'Driscoll, N.Stanley, C.R., O'Driscoll, N., Ranjan, P.Determining the magnitude of true analytical error in geochemical analysis.Geochemistry: Exploration, Environment, Analysis, Vol. 10, 4, pp. 355-364.TechnologyGeochemistry - not specific to diamonds
DS1995-1375
1995
Odum, J.K.Odum, J.K., Luzietti, E.A., et al.High resolution, shallow seismic reflection surveys of northwest Reelfoot Rift Boundary, near Marston.United States Geological Survey (USGS) Prof. paper, No. 1538- P, 18p.Missouri, MidcontinentGeophysics - seismics, Mississippi Embayment
DS200512-0797
2005
OECD Development CentreOECD Development CentreAfrican Economic Outlook 2004/2005: Angola.Organization for Economic Cooperation and Development, ingenta pub = infobike: //oecd/16080173, Sept. No. 5, pp. 68-81.Africa, AngolaEconomics
DS200512-0798
2005
OECD Development CentreOECD Development CentreAfrican Economic Outlook 2004/2005: BotswanaOrganization for Economic Cooperation and Development, ingenta pub = Infobike: //oecd/16080173, Sept. No. 5, pp. 97-111.Africa, BotswanaEconomics
DS1994-1297
1994
OECD.OECD.Mining and non-ferrous metals policies of OECD countriesOecd., 322p. approx. $ 90.00Australia, CanadaBook -ad and review, Mining, metal policiies
DS1984-0762
1984
Oehm, J.Wedepohl, K.H., Mengel, K., Oehm, J.Depleted Mantle Rocks and Metasomatically Altered Peridotite Inclusions in Tertiary Basalts from the Hessian Depression northwest Germany.Proceedings of Third International Kimberlite Conference, Vol. 2, PP. 190-201.GermanyRelated Rocks, Mineral Composition
DS1996-1198
1996
Oehm, J.Rochell, A., Heusser, E., Kirsten, T., Oehm, J., RichterA noble gas profile across a Hawaiian mantle xenolith: coexisting accidental and cognate noble gases derivedGeochimica et Cosmochimica Acta, Vol. 60, No. 23, pp. 4773-83.Mantle, HawaiiGeochemistry - ultramafic xenoliths, Geochronology
DS2002-0576
2002
Oelkers, E.H.Gislason, S.R., Oelkers, E.H., Bruno, J.Geochemistry of crustal fluids: an Andalusian perspectiveChemical Geology, Vol. 190, 1-4, pp.MantleGeochemistry
DS201412-0418
2014
Oelofsen, A.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
DS1993-1801
1993
Oertel, G.Yin, A., Oertel, G.Kinematics and strain distribution of a thrust related fold system in the Lewis Plate, northwestern Montana.Journal of Structural Geology, Vol. 15, No. 6, pp. 707-19.MontanaTectonics, structure
DS201802-0255
2018
Oeser, M.Neave, D.A., Shorttle, O., Oeser, M., Weyer, S., Kobayashi, K.Mantle derived trace element variability in olivines and their melt inclusions.Earth and Planetary Science Letters, Vol. 483, 1, pp. 90-104.Europe, Icelandolivines

Abstract: Trace element variability in oceanic basalts is commonly used to constrain the physics of mantle melting and the chemistry of Earth's deep interior. However, the geochemical properties of mantle melts are often overprinted by mixing and crystallisation processes during ascent and storage. Studying primitive melt inclusions offers one solution to this problem, but the fidelity of the melt-inclusion archive to bulk magma chemistry has been repeatedly questioned. To provide a novel check of the melt inclusion record, we present new major and trace element analyses from olivine macrocrysts in the products of two geographically proximal, yet compositionally distinct, primitive eruptions from the Reykjanes Peninsula of Iceland. By combining these macrocryst analyses with new and published melt inclusion analyses we demonstrate that olivines have similar patterns of incompatible trace element (ITE) variability to the inclusions they host, capturing chemical systematics on intra- and inter-eruption scales. ITE variability (element concentrations, ratios, variances and variance ratios) in olivines from the ITE-enriched Stapafell eruption is best accounted for by olivine-dominated fractional crystallisation. In contrast, ITE variability in olivines and inclusions from the ITE-depleted Háleyjabunga eruption cannot be explained by crystallisation alone, and must have originated in the mantle. Compatible trace element (CTE) variability is best described by crystallisation processes in both eruptions. Modest correlations between host and inclusion ITE contents in samples from Háleyjabunga suggest that melt inclusions can be faithful archives of melting and magmatic processes. It also indicates that degrees of ITE enrichment can be estimated from olivines directly when melt inclusion and matrix glass records of geochemical variability are poor or absent. Inter-eruption differences in olivine ITE systematics between Stapafell and Háleyjabunga mirror differences in melt inclusion suites, and confirm that the Stapafell eruption was fed by lower degree melts from greater depths within the melting region than the Háleyjabunga eruption. Although olivine macrocrysts from Stapafell are slightly richer in Ni than those from Háleyjabunga, their overall CTE systematics (e.g., Ni/(Mg/Fe), Fe/Mn and Zn/Fe) are inconsistent with being derived from olivine-free pyroxenites. However, the major element systematics of Icelandic basalts require lithological heterogeneity in their mantle source in the form of Fe-rich and hence fusible domains. We thus conclude that enriched heterogeneities in the Icelandic mantle are composed of modally enriched, yet nonetheless olivine-bearing, lithologies and that olivine CTE contents provide an incomplete record of lithological heterogeneity in the mantle. Modally enriched peridotites may therefore play a more important role in oceanic magma genesis than previously inferred.
DS1995-1376
1995
Oesterien, P.M.Oesterien, P.M., Millsteed, B.D.Lithostratigraphy, paleontology and sedimentary environments of the western Cabora Bassa Basin, ZambeziSouth African Journal of Geology, Vol. 97, No. 2, pp. 205-224ZimbabweKaroo Supergroup, Zambezi Valley
DS1950-0114
1952
Oesterling, W.A.Oesterling, W.A. , Landes, K.K.Geologic and Economic Significance of the Huston Zinc Mine, salem Kentucky Fluorspar District.Economic Geology, Vol. 47, No. 3, PP. 316-338.GlobalKimberlite, Western Kentucky, Central States
DS1994-1298
1994
O'Faircheallaigh, C.O'Faircheallaigh, C.Mabo, mining and aborginal Australia: an alternative perspectiveCrs Perspectives, No. 49, April pp. 9-15AustraliaLegal, Native rights
DS201312-0663
2013
O'Faircheallaigh, C.O'Faircheallaigh, C.CSR, the mining industry and indigenous peoples in Australia and Canada.Innovative CSR: From risk Management to value creation. Greenleaf Publishing Limited, Vol. 1, no. 46, pp. 398-418.Australia, CanadaCSR, aboriginals
DS1990-0167
1990
Often, M.Barnes, S.J., Often, M.Ti-rich komatiites from northern NorwayContributions to Mineralogy and Petrology, Vol. 105, No. 1, pp. 42-54NorwayKomatiites, titanium, Greenstone belt
DS1975-0590
1977
Ofunguo, A.C.Ofunguo, A.C.History of Labour on the Mwadui Diamond MineDar Es Salaam: M.a. Thesis, University Dar Es Salaam., 143P.Tanzania, East AfricaPolitics, Mining
DS200912-0343
2009
Oganov, A.Jones, A.P., Oganov, A.Superdeep carbonate melts in the Earth.Goldschmidt Conference 2009, p. A601 Abstract.MantleMelting
DS2002-1171
2002
Oganov, A.R.Oganov, A.R., Price, G.D., Brodholt, J.P.Theory of MgSiO3 perovskite: towards a thermal and mineralogical model of the Earth's mantle.18th. International Mineralogical Association Sept. 1-6, Edinburgh, abstract p.70.MantleUHP - mineralogy
DS2003-0169
2003
Oganov, A.R.Brodholt, J.P., Oganov, A.R., Price, G.D.Computational mineral physics and the physical properties of perovskitePhilosophical Transactions of the Royal Society of London, Vol. 360, 1800, pp. 2507-20.GlobalMineralogy, mantle, perovskite
DS200412-0216
2003
Oganov, A.R.Brodholt, J.P., Oganov, A.R., Price, G.D.Computational mineral physics and the physical properties of perovskite.Philosophical Transactions of the Royal Society of London Series A Mathematical Physical and Engineering Sciences, Vol. 360, 1800, pp. 2507-20.TechnologyMineralogy, mantle, perovskite
DS200612-1016
2006
Oganov, A.R.Ono, S., Oganov, A.R., Koyama, T., Shimizu, H.Stability and compressibility of the high pressure phases of AL203 up to 200 GPa: implications for the electrical conductivity of the base of the lower mantle.Earth and Planetary Science Letters, Vol. 246, 3-4, pp. 326-335.MantleGeophysics - seismics
DS200712-1224
2006
Oganov, A.R.Zhang, F., Oganov, A.R.Valence state and spin transitions of iron in Earth's mantle silicates.Geochimica et Cosmochimica Acta, In press availableMantleD layer, perovskites
DS200812-0812
2008
Oganov, A.R.Oganov, A.R., Ono, S., Ma, Y., Glass, C.W., Garcia, A.Novel high pressure structures of MgCo3, CaCo3 and CO2 and their role in Earth's lower mantle.Earth and Planetary Science Letters, Vol. 273, pp. 38-47.MantleUHP, Carbon storage
DS200512-0790
2004
OgasawaraNokleberg, W.J., Bararch, G.Berzin, Diggles, Hwang, Khanchuk, Miller, Naumova, Oblenskiy, Ogasawara, ParfemicDigital files for northeast Asia, geodynamics, mineral deposit location and metallogenic belt maps. stratigraphic columns, map units.U.S. Geological Survey, Open file 2004-1252Russia, ChinaMaps - geodynamics - not specific to diamonds
DS1995-1099
1995
Ogasawara, Y.Liou, J.G., Ogasawara, Y., Zhang, R.Y.Occurrence and stability of diamond bearing assemblages in ultrahigh pressure metamorphic rocks.Proceedings of the Sixth International Kimberlite Conference Abstracts, pp. 328-330.Russia, KazakhstanMetamorphic, Deposit -Kokchetav
DS1997-0866
1997
Ogasawara, Y.Ogasawara, Y., Liou, J.G., Zhang, R.Y.Thermochemical calculation of log FO2 -T-P stability relations of Diamond bearing system CaOMgOSiO2CO2H2O.Russian Geology and Geophysics, Vol. 38, No. 2, pp. 587-598GlobalPetrology - petrochemistry, experimental, Diamond bearing system
DS2002-0813
2002
Ogasawara, Y.Kataayama, I., Ohta, M., Ogasawara, Y.Phengite exsolution in diopside in diamond bearing marble from Kumdy KolFrontiers Science Series, University Academy Press, Vol. 38, pp. 181-190.ChinaPetrology
DS2002-0814
2002
Ogasawara, Y.Katayama, I., Ohta, M., Ogasawara, Y.Mineral inclusions in zircon from diamond bearing marble in the Kokchetav massif, northern Kazakhstan.European Journal of Mineralogy, Vol. 14, No. 6, pp. 1103-1108.Russia, KazakhstanDiamond - inclusions
DS2002-0951
2002
Ogasawara, Y.Liou, J.G., Ernst, W.G., Ogasawara, Y.Petrochemical and tectonic processes of UHP/HP terranes: I. prefaceInternational Geology Review, Vol. 44, No. 9, pp. 765-9.GlobalTectonics, Ultrahigh Pressure
DS2002-1172
2002
Ogasawara, Y.Ogasawara, Y., Ohta, M., Fukasawa, K., Katayama, I., Maruyama, S.Petrology of diamond bearing dolomite marble from Kumdy KolFrontiers Science Series, University Academy Press, Vol. 38, pp. 191-212.ChinaPetrology
DS2002-1180
2002
Ogasawara, Y.Okamoto, K., Liou, J.G., Ogasawara, Y.Petrology of diamond grade eclogite from Kumdy KolFrontiers Science Series, University Academy Press, Vol. 38, pp. 235-256.ChinaEclogites
DS2002-1794
2002
Ogasawara, Y.Zhu, Y., Ogasawara, Y.Phlogopite and coesite exsolution from super silici clinopyroxeneInternational Geology Review, Vol. 44, 9, pp. 831-36.GlobalPetrology
DS2002-1795
2002
Ogasawara, Y.Zhu, Y., Ogasawara, Y.Carbon recycled into deep earth: evidence from dolomite association in subduction zone arc.Geology, Vol. 30, 10, Oct. pp. 947-50.RussiaUHP, texture, subduction, diamond, Kochetav Massif
DS2002-1796
2002
Ogasawara, Y.Zhu, Y., Ogasawara, Y., Ayabe, T.The mineralogy of the Kokchetav 'lamproite': implications for the magma evolutionJournal of Volcanology and Geothermal Research, Vol.116, 1-2, pp. 35-61.RussiaPetrology - clinopyroxene, magnetite, Deposit - Kokchetav
DS2003-0624
2003
Ogasawara, Y.Ishida, H., Ogasawara, Y., Ohsumi, K., Saito, A.Two stage growth of microdiamond in UHP dolomite marble from Kokechtav MassifJournal of Metamorphic Geology, Vol. 21, 6, pp. 515-22.Russia, KazakhstanMicrodiamonds - morphology
DS2003-1028
2003
Ogasawara, Y.Ohta, M., Mock, T., Ogasawara, Y., Rumble, D.Oxygen, carbon, and strontium isotope geochemistry of diamond bearing carbonateLithos, Vol. 70, 3-4, pp. 77-90.Russia, KazakhstanGeochemistry
DS200412-0876
2003
Ogasawara, Y.Ishida, H., Ogasawara, Y., Ohsumi, K., Saito, A.Two stage growth of microdiamond in UHP dolomite marble from Kokechtav Massif, Kazakhstan.Journal of Metamorphic Geology, Vol. 21, 6, pp. 515-22.Russia, KazakhstanMicrodiamonds - morphology
DS200412-0959
2002
Ogasawara, Y.Kataayama, I., Ohta, M., Ogasawara, Y.Phengite exsolution in diopside in diamond bearing marble from Kumdy Kol.Frontiers Science Series, University Academy Press, Vol. 38, pp. 181-190.ChinaPetrology
DS200412-1458
2002
Ogasawara, Y.Ogasawara, Y., Ohta, M., Fukasawa, K., Katayama, I., Maruyama, S.Petrology of diamond bearing dolomite marble from Kumdy Kol.Frontiers Science Series, University Academy Press, Vol. 38, pp. 191-212.ChinaPetrology
DS200412-1460
2003
Ogasawara, Y.Ohta, M., Mock, T., Ogasawara, Y., Rumble, D.Oxygen, carbon, and strontium isotope geochemistry of diamond bearing carbonate rocks from Kumdy Kol, Kochetav Massif, KazakhstaLithos, Vol. 70, 3-4, pp. 77-90.Russia, KazakhstanGeochemistry
DS200412-1463
2002
Ogasawara, Y.Okamoto, K., Liou, J.G., Ogasawara, Y.Petrology of diamond grade eclogite from Kumdy Kol.Frontiers Science Series, University Academy Press, Vol. 38, pp. 235-256.ChinaEclogite
DS200412-1716
2004
Ogasawara, Y.Sachan, H.K., Mukherjee, B.K., Ogasawara, Y., Mauyama, S., Ishida, H., Muko, A., Yoshioka, N.Discovery of coesite from Indus Suture Zone (ISZ) Ladakh India: evidence for deep subduction.European Journal of Mineralogy, Vol. 16, 2, pp. 235-240.IndiaSubduction
DS200412-2230
2004
Ogasawara, Y.Zhu, Y., Ogasawara, Y.Clinopyroxene phenocrysts ( with green salite cores) in trachybasalts: implications for two magma chambers under the Kokchetav UJournal of Asian Earth Sciences, Vol. 22, 5, January pp. 517-527.Russia, KazakhstanUHP, magma mixing, subduction
DS200512-0499
2004
Ogasawara, Y.Katayama, I., Ohta, M., Ogasawara, Y.Mineral inclusions in zircon from diamond bearing marble in the Kokchetav Massif, northern Kazakhstan.European Journal of Mineralogy, Vol. 14, 6, pp. 1103-1108.Russia, KazakhstanMineral inclusions
DS200512-0789
2005
Ogasawara, Y.Nobuhiro, Y., Ogasawara, Y.Cathodluminescence of microdiamond in dolomite marble from the Kokehetav Massif - additional evidence for two stage growth of diamond.International Geology Review, Vol. 47, 7, July pp. 703-715.RussiaMicrodiamond morphology
DS200512-0799
2005
Ogasawara, Y.Ogasawara, Y.Microdiamonds in ultrahigh pressure metamorphic rocks.Elements, Vol. 1, 2, March pp. 91-96.Russia, MantleUHP, continental collision, Kokchetav
DS200512-1221
2005
Ogasawara, Y.Yoshioka, N., Ogasawara, Y.Cathodluminesence of microdiamond in dolomite marble from the Kokchetav massif - additional evidence for two stage growth in diamond.International Geology Review, Vol. 47, 7, pp. 703-715.RussiaMicrodiamonds
DS200612-0698
2006
Ogasawara, Y.Kikuchi, M., Ogasawara, Y.Occurrence and characterization of UHPM microdiamonds from the Kokchetav Massif.International Mineralogical Association 19th. General Meeting, held Kobe, Japan July 23-28 2006, Abstract p. 139.RussiaKochetav - microdiamond
DS200612-0699
2006
Ogasawara, Y.Kikuchi, M., Ogasawara, Y.Hydroxyl in diopside of diamond free ultrahigh pressure dolomitic marble from Kokchetav Massif, Kazakhstan.Geological Society of America, In: Hacker, B.R., McClelland, Liou: Ultra High Pressure Metamorphism, Special Paper 403, pp. 139-145.RussiaUHP
DS200612-0998
2006
Ogasawara, Y.Ogasawara, Y.Microdiamond formation during intraslab UHP metasomatism: an example from the Kokchetav Massif.International Mineralogical Association 19th. General Meeting, held Kobe, Japan July 23-28 2006, Abstract p. 139.RussiaKochetav - microdiamond
DS200612-0999
2005
Ogasawara, Y.Ogasawara, Y., Aoki, K.The role of fluid for diamond free UHP dolomitic marble from the Kokchetav Massif.International Geology Review, Vol. 47, 11, pp. 1178-1193.RussiaUHP
DS200612-1285
2006
Ogasawara, Y.Shimizu, R., Ogasawara, Y.Characterization of microdiamonds in K-tourmaline rich UHP rock by raman spectroscopy.International Mineralogical Association 19th. General Meeting, held Kobe, Japan July 23-28 2006, Abstract p. 140.RussiaKokchetav Massif, Microdiamonds
DS201312-0427
2013
Ogasawara, Y.Imamura, K., Ogasawara, Y., Yurimoto, H., Kusakabe, M.Carbon isotope heterogeneity in metamorphic diamond from the Kokchetav UHP dolomite marble, northern Kazakhstan.International Geology Review, Vol. 55, 4, pp. 453-467.Russia, KazakhstanDeposit- Kokchetav
DS201312-0772
2014
Ogasawara, Y.Sakamaki, K., Ogasawara, Y.Hydroxyl in clinopyroxene and titanite in a UHP diamond free garnet clinopyroxene rock from the Kokchetav Massif, northern Kazakhstan.International Geology Review, Vol. 56, 2, pp. 133-149.Russia, KazakhstanDeposit - Kokchetav
DS201412-0770
2014
Ogasawara, Y.Sakamaki, K., Ogasawara, Y.Hydroxyl in clinopyroxene and titanite in a UHP diamond-free-garnet-clinopyroxene rock from the Kokchetav Massif, northern Kazakhstan.International Geology Review, Vol. 56, 2, pp. 133-149.Russia, KazakhstanKokchetav massif
DS201412-0811
2014
Ogasawara, Y.Shimizu, R., Ogasawara, Y.Radiation damage to Kokchetav UHPM diamonds in zircon: variations in Raman, photoluminescence and cathodluminesence spectra.Lithos, Vol. 206-207, pp. 201-213.TechnologyMicrodiamonds
DS201608-1436
2016
Ogasawara, Y.Sakamaki, K., Sato, Y., Ogasawara, Y.Hydrous Na-garnet from Garnet Ridge products of mantle metasomatism underneath the Colorado Plateau.Progress in Earth and Planetary Science, Vol. 3, 20, 17p.United States, Colorado PlateauMetasomatism

Abstract: This is the first report on amphibole exsolution in pyrope from the Colorado Plateau. Pyrope crystals delivered from mantle depths underneath the Colorado Plateau by kimberlitic volcanism at 30 Ma were collected at Garnet Ridge, northern Arizona. The garnet grains analyzed in this study occur as discrete crystals (without adjacent rock matrix) and are classified into two major groups, Cr-rich pyrope and Cr-poor pyrope. The Cr-poor pyrope group is divided into four subgroups based on exsolved phases: amphibole lamella type, ilmenite lamella type, dense lamellae type, and clinopyroxene/amphibole lamellae type. Exsolved amphibole occurs in amphibole lamella type, dense lamellae type, and clinopyroxene/amphibole lamellae type of Cr-poor pyrope. The amphibole crystals tend to have preferred orientations in their garnet hosts and occur as monomineralic hexagonal or rhombic prisms and tablets, and as multimineralic needles or blades with other exsolved phases. Exsolved amphibole has pargasitic compositions (Na2O up to 1.6 apfu based on 23 oxygen). Garnet host crystals that have undergone amphibole exsolution have low OH contents (2-42 ppmw H2O) compared to garnets that do not have amphibole lamellae (up to 115 ppmw H2O). The low OH contents of garnets hosting amphibole lamellae suggest loss of OH from garnet during amphibole exsolution. Amphibole exsolution from pyrope resulted from breakdown of a precursor “hydrous Na-garnet” composition (Mg,Na+ x)3(Al2?-?x, Mgx)2Si3O12?-?2x(OH)2x. Exsolution of amphibole and other phases probably occurred during exhumation to depths shallower than 100 km prior to volcanic eruption. Based on the abundance and composition of exsolved clinopyroxene and amphibole lamellae in one garnet, hydrous Na-garnet had excess silicon (Si3.017 apfu, 12 oxygen normalization, vs. X3Y2Si3O12 for typical garnet). Comparison with experimental data suggests crystallization at pressures near 6-8 GPa. Garnet crystals that host exsolved amphibole have compositions (Pyp49-76, 3-10 wt% CaO, and up to 0.6 wt% Cr2O3) similar to garnets reported from pyroxenites, and have pyrope-almandine-grossular compositional ranges that overlap with the Cr-rich pyrope (typical lherzolitic garnet). Hydrous Na-garnet was likely formed by metasomatic reactions between Cr-rich pyrope and Na-rich aqueous fluid in the deep upper mantle. The most likely source of metasomatic Na-rich fluid is ancient oceanic crust that was subducted before subduction of the Farallon Plate beneath the Colorado Plateau.
DS201603-0406
2015
Ogasawara Y.Ogasawara Y., Shimizu, R., Sakamaki, K.Diversity of the Kokchetav metamorphic diamonds and their formation related to h ( sub 2) o-rich fluid conditions.Geological Society of America Annual Meeting, Vol. 47, 7, p. 169. abstractRussiaMetamorphic diamonds

Abstract: The metamorphic diamonds in the Kokchetav Massif show very diverse features in morphologies and grain sizes with other crystal characters, Raman spectra (FWHM, PL), cathodoluminescence spectra, C isotope, abundance, paragenesis with silicates and carbonates. The formations of these diamonds, however, seem to be related to H2O-fluid conditions. Dolomite marble has the highest abundance in diamond. The diamond grew at two stages and 2nd stage growth was from H2O fluid. Grt-Bt gneiss is 2nd highest and the diamond shows several morphologies; however, no 2nd stage growth. In dolomite marble, diamond at 2nd stage has light carbon isotope, -17 to -27 whereas 1st stage diamond has -8 to -15. The light carbon of 2nd stage could be organic carbon in gneisses carried by H2O-fluid; dissolution of diamond in gneisses could have occurred. No 2nd stage growth in gneisses supports this idea. Carbon-bearing H2O fluid infiltration into dolomite marble caused the change of carbon solubility in fluid to precipitate abundant fine diamonds (10-20 mm), quickly. Recently discovered sp2 graphitic carbon inclusions in 2nd stage diamond (AGU2014F V13B-4771), which is a relic of metastable intermediate phase for diamond formation, suggest the diamond participation from H2O fluid. A minor amount of diamond (large-grained, ca. 150 µm at average) occurs in Grt-Cpx rock. Recently, we found the overgrowth of large-grained cubic diamond on small-grained one by multi-layered 2D Raman mappings (JpGU2014 No.02541). This indicates slow-growth in H2O-fluid having low oversaturation degree of carbon. UHP calcite marble contains a trace amount of small-grained diamond (no 2nd stage growth) only in diopside; titanite with coesite exsolution does not contain diamond. These suggest that very high H2O activity for titanite stability makes diamond unstable, and dissolution of diamond was possible. This is a similar relation with UHP dolomitic marble, which Arg-Fo and Arg-Ti-Chum were stable but diamond was unstable. In Tur-Fel-Qtz rock, diamond is included in new mineral "maruyamaite" (K-rich Tur); recent experiments show high-P and fluid-bearing conditions for maruyamaite. Summarizing these diverse features of the Kokchetav diamonds, those formation and their possible dissolutions have strong relationships with H2O-fluid conditions.
DS201112-0752
2011
Ogassawara, Y.Ogassawara, Y., Hasiguchi, Y., Igarashi, M., Harada, Y.Microdiamonds: a relict of intermediate phase for diamond formation.Geological Society of America, Annual Meeting, Minneapolis, Oct. 9-12, abstractRussiaKokchetav massif, UHP
DS200412-0590
2004
Ogawa, H.Fujino, K., sasaki, Y., Komori, T., Ogawa, H., Miyajima, N., Sata, N., Yagi, T.Approach to the mineralogy of the lower mantle by a combined method of a laser heated diamond anvil cell experiment and analyticPhysics of the Earth and Planetary Interiors, Vol. 143-144, pp. 215-221.MantleMineralogy - experimental
DS1988-0518
1988
Ogawa, M.Ogawa, M.Numerical experiments on coupled magmatism mantle convection system:implications for mantle evolution and Archean continental crustsJournal of Geophysical Research, Vol. 93, No. B12, December 10, pp. 15, 119-15, 135GlobalMantle, Magmatism
DS1994-1299
1994
Ogawa, M.Ogawa, M.Effects chem fractionation of heat producing elements on mantle evolution inferred model of coupled magmatismPhys. Earth and Planetary Interiors, Vol. 83, No. 2, May pp. 101-128.MantleMagmatism, Mantle convection systems
DS1998-1089
1998
Ogawa, M.Ogawa, M.Numerical models of coupled magmatism mantle convection system applied To the early mantle.Geological Society of America (GSA) Annual Meeting, abstract. only, p.A207-8.MantleMagmatism, Convection
DS2000-0724
2000
Ogawa, M.Ogawa, M.Coupled magmatism - mantle convection system with variable viscosityTectonophysics, Vol. 322, No. 1-2, pp. 1-18.MantleMagmatism - convection
DS2000-0725
2000
Ogawa, M.Ogawa, M.Coupled magmatism mantle convection system with variable viscosityTectonophysics, Vol.322, No.1-2, July10, pp.1-18.MantleMagmatism, Convection
DS2003-1027
2003
Ogawa, M.Ogawa, M.Chemical stratification in a two dimensional convecting mantle with magmatism andJournal of Geophysical Research, Vol. 108, B12, 2561 10.1029/2002JB002205MantleMagmatism, geochemistry
DS200412-1459
2003
Ogawa, M.Ogawa, M.Chemical stratification in a two dimensional convecting mantle with magmatism and moving plates.Journal of Geophysical Research, Vol. 108, B12, 2561 10.1029/2002 JB002205MantleMagmatism, geochemistry
DS200412-2186
2004
Ogawa, M.Yoshida, M., Ogawa, M.The role of hot uprising plumes in the initiation of plate like regime of three dimensional mantle convection.Geophysical Research Letters, Vol. 31, 5, March 16, DOI 10.1029/2003 GLO17376MantleHotspots
DS200612-1575
2005
Ogawa, M.Yoshida, M., Ogawa, M.Plume heat flow in a numerical model of mantle convection with moving plates.Earth and Planetary Science Letters, Vol. 239, 3-4, pp. 276-285.MantleConvection
DS200712-0784
2007
Ogawa, M.Ogawa, M.Superplumes, plates and mantle magmatism in two dimensional numerical models.Journal of Geophysical Research, Vol. 112, B 6, B06404MantleMagmatism
DS200712-0785
2007
Ogawa, M.Ogawa, M.Superplumes, plates and mantle magmatism in two dimensional numerical models.Journal of Geophysical Research, Vol. 112, B6 B06404.MantleMagmatism
DS200812-0813
2008
Ogawa, M.Ogawa, M.Mantle convection: a review.Fluid Dynamic Research, Vol. 40, 6, pp. 379-398.MantleConvection
DS201312-0283
2013
Ogawa, M.Fujita, K., Ogawa, M.A preliminary numerical study on water-circulation in convecting mantle with magmatism and tectonic plates.Physics of the Earth and Planetary Interiors, Vol. 216, pp. 1-11.MantleMagmatism, Convection
DS200412-1621
2004
Ogawa, Y.Rao, C.K., Ogawa, Y., Gokarn, S.G., Gupta, G.Electromagnetic imaging of magma across the Narmada Son lineament, central India.Earth Planets and Space, Vol. 56, 2, pp. 229-238.. IngentaIndiaGeophysics - magnotellurics
DS200812-0814
2008
Ogden, D.E.Ogden, D.E., Glatzmaier, G.A.Effects of vent overpressure on buoyant eruption columns: implications for plume stability.Earth and Planetary Science Letters, Vol. 268, no. 3-4, April. 30, pp. 283-292.MantleGeophysics
DS201810-2362
2018
Ogden, J.Ogden, J.Diamonds - an early history of the King of Gems. Yale University Press, 408p. ISBN 978-0300215663Globalhistory

Abstract: This richly illustrated history of diamonds illuminates myriad facets of the “king of gems,” including a cast of larger-than-life characters such as Alexander the Great, the Mughal emperor Jahangir, and East India Company adventurers. It’s an in-depth study tracing the story of diamonds from their early mining and trade more than two thousand years ago to the 1700s, when Brazil displaced India as the world’s primary diamond supplier. Jack Ogden, a historian and gemologist specializing in ancient gems and jewelry, describes the early history of diamond jewelry, the development of diamond cutting, and how diamonds were assessed and valued. The book includes more than one hundred captivating images, from close-up full-color photographs of historic diamond-set jewelry (some previously unpublished), to photomicrographs of individual gems and illustrations of medieval manuscripts, as well as diagrams depicting historical methods of cutting and polishing diamonds.
DS202009-1648
2019
Ogden, J.Ogden, J.History, heritage and hype behind Golgonda diamondsGems & Jewellery, Vol. 29, 3, autumn pp. 38-40.Indiadeposit - Golconda
DS201705-0867
2017
Ogden, J.M.Ogden, J.M.Rethinking laboratory reports for the geographical origin of gems.Journal of Gemmology, Vol. 35, 5, pp. 416-423.TechnologyReports - gem reports, tests, grades

Abstract: The proliferation of gemmological laboratory reports and the need for transparency to best protect against litigation suggest that some gem-testing laboratories should consider changes in the wording and content of their geographical origin reports. Based on the author's recent broader study of the legal aspects of the opinions provided by experts in the field of art and antiques, the main proposals presented here are that statements of opinion rather than fact should be clearly expressed as such where they are presented on a report, rather than relegating all mention of 'opinion' to the 'terms and conditions', and that the basic nature of the observational or analytical evidence on which any opinions are based should be noted. In addition, a laboratory might usefully provide some indication of the level of confidence in its opinion.
DS201904-0762
2019
Ogden, J.M.Ogden, J.M.Out of the Blue: The Hope diamond in London.Journal of Gemology, Vol. 36, 4, pp. 316-331.Globaldiamonds notable
DS201907-1564
2019
Ogden, J.M.Ogden, J.M.Mr. Hornby's diamonds: its travels, diplomatic role and possible equation with the Nur al-'Ayn. Sancy diamondJournal of Gemmology, Vol. 36, 6, pp. 512-523.Indiadiamonds notable
DS1984-0752
1984
Ogden, P.Vollmer, R., Ogden, P., Schilling, J.G., Kingsley, R.H.Neodymium and Strontium Isotopes in the Ultrapotassic Volcanic Rocks from the Leucite Hills, Wyoming.Contributions to Mineralogy and Petrology, Vol. 87, No. 4, PP. 359-368.United States, Wyoming, Leucite HillsGeochronology
DS1990-0612
1990
Ogden, P.Gunter, W.D., Hoinkes, G., Ogden, P., Pajari, G.E.Origin of leucite rich and sanidine roch flow layers in the Leucite Hills volcanic field, WyomingJournal of Geophysical Research, Vol. 95, No. B 10, September 10, pp. 15, 911-15, 928WyomingLeucite, Lamproite -orendite
DS1975-0591
1977
Ogden, P.R.JR.Ogden, P.R.JR., Gunter, W.D., Fandry, C.B.A New Occurrence of Madupite: Leucite Hills, WyomingGeological Society of America (GSA), Vol. 9, No. 6, P. 754, (abstract.).GlobalLeucite Hills, Leucite, Rocky Mountains
DS1975-0828
1978
Ogden, P.R.JR.Ogden, P.R.JR.Evidence for Contamination in the Petrogenesis of Madupite, leucite Hills, Wyoming.Geological Society of America (GSA), Vol. 10, No. 7, P. 465, (abstract.).GlobalRocky Mountains, Leucite Hills, Leucite
DS1975-0829
1978
Ogden, P.R.JR.Ogden, P.R.JR., Sperr, J.T., Gunter, W.D.Morphology of a Recent Ultrapotassic Volcanic Field, Leucite Hills, Southwestern Wyoming.Geological Society of America (GSA), Vol. 10, No. 3, P. 140, (abstract.).GlobalRocky Mountains, Leucite Hills, Leucite
DS1975-1170
1979
Ogden, P.R.JR.Ogden, P.R.JR.The Geology, Major Element Geochemistry and Petrogenesis Of the Leucite Hills Volcanic Rocks, Wyoming.Ph.d. Thesis, University Wyoming, 213P.GlobalLamproite
DS1975-1218
1979
Ogden, P.R.JR.Sheriff, S.D., Shive, P.N., Ogden, P.R.JR.Paleomagnetism of the Leucite Hills of Southwestern WyomingEos, Vol. 60, No. 18, PP. 244-245. (abstract.).GlobalLeucite, Rocky Mountains
DS1980-0263
1980
Ogden, P.R.JR.Ogden, P.R.JR., Vollmer, R., Schilling, J.G.Leucite Hills Revisited 87/sr and 86/sr EvidenceEos, Vol. 61, No. 17, P. 388, (abstract.).GlobalLeucite Hills, Leucite, Rocky Mountains
DS201112-0753
2011
Ogilvie-HarrisOgilvie-HarrisImplications of volcanic processes from the petrology of the AK06 South Lobe kimberlite.IUGG Held July 6, AbstractAfrica, BotswanaDeposit - AK06
DS201212-0694
2012
Ogilvie-Harris, R.Sparks, R.S.J., Buisman, I., Brooker, R., Brown, R.J., Field, M., Gernon, T., Kavanagh,J., Ogilvie-Harris, R., Schumacher, J.C.Dynamics of kimberlite magam ascent, intrusion and eruption.10th. International Kimberlite Conference Feb. 6-11, Bangalore India, AbstractGlobalDiamond genesis
DS200912-0249
2009
Ogilvie-Harris, R.C.Gernon, T.M., Sparks, R.S., Field, M., Ogilvie-Harris, R.C.Geological constraints on the emplacement of the Snap lake kimberlite dyke, NW Territories, Arctic Canada.GAC/MAC/AGU Meeting held May 23-27 Toronto, Abstract onlyCanada, Northwest TerritoriesDeposit - Snap Lake
DS200912-0547
2009
Ogilvie-Harris, R.C.Ogilvie-Harris, R.C., Sparks, R.S., Field, M., Gernon, T.M.The geochemistry of the Snap Lake kimberlite dyke, Northwest Territories: phlogopite and spinel.GAC/MAC/AGU Meeting held May 23-27 Toronto, Abstract onlyCanada, Northwest TerritoriesDeposit - Snap Lake
DS201012-0546
2009
Ogilvie-Harris, R.C.Ogilvie-Harris, R.C., Field, M., Sparks, R.S.J., Walter, M.J.Perovskite from the Dutoitspan kimberlite, Kimberley, South Africa: implications for magmatic processes.Mineralogical Magazine, Vol. 73, no. 6, pp. 915-928.Africa, South AfricaDeposit - Dutoitspan
DS201212-0236
2012
Ogilvie-Harris, R.C.Gernon, T.M.I., Ogilvie-Harris, R.C., Sparks, R.S.J.,Field, M.Emplacement of the Snap Lake kimberlite intrusion, Northwest Territories, Canada.10th. International Kimberlite Conference Feb. 6-11, Bangalore India, AbstractCanada, Northwest TerritoriesDeposit - Snap Lake
DS201212-0529
2012
Ogilvie-Harris, R.C.Ogilvie-Harris, R.C., Field, M., Brooker, R.A., Walter, M.J., Sparks, R.S.J.The petrology of AK6, Botswana: implications of volcanic and igneous processes.10th. International Kimberlite Conference Feb. 6-11, Bangalore India, AbstractAfrica, BotswanaDeposit - AK6
DS201212-0530
2012
Ogily-Harris, R.C.Ogily-Harris, R.C., Brooker, R.A., Sparks, R.S.J., Walter, M.J.An experimental investigation of the carbonatite-kimberlite melt.10th. International Kimberlite Conference Held Bangalore India Feb. 6-11, Poster abstractAfrica, South AfricaDeposit - Dutoitspan
DS1960-1006
1968
Oglesby, J.C.Oglesby, J.C.Final Report on the Lee Creek Concession Area. M.e.l. 300New South Wales Geological Survey Report., GS 1968/231, (UNPUBL.).AustraliaKimberlite, Diamond, Prospecting
DS1960-1007
1968
Oglesby, J.C.Oglesby, J.C.Final Report on the Carrow Creek Concession Area. M.e.l. 299 and 323.New South Wales Geological Survey Report., GS 1968/263, (UNPUBL.).AustraliaKimberlite, Diamond, Prospecting
DS1970-0165
1970
Oglesby, J.C.Oglesby, J.C.E.l. 281, Bingara. Report for the Period 22.8.70- 22.11.70New South Wales Geological Survey Report., GS 1970/629, (UNPUBL.).AustraliaKimberlite, Diamond, Prospecting
DS1970-0166
1970
Oglesby, J.C.Oglesby, J.C.E.l. 280, Kyogle Area. Report for the Period 22.8.70- 22.11.70.New South Wales Geological Survey Report., GS 1970/630, (UNPUB.).AustraliaKimberlite, Diamond, Prospecting
DS1970-0167
1970
Oglesby, J.C.Oglesby, J.C.A Study of Distribution and Origin of Diamond Deposits in New South wales.Stockdale Exploration Ltd. Report., ( UNPUBL.).AustraliaKimberlite, Prospecting
DS1970-0650
1973
Oglesby, J.C.Colchester, D.M., Oglesby, J.C., Pallett, J.J.Sml 706 Formerly Sml 307 Nackara South Australia Progress And Final Report from 25/5/72 to 24/5/73.South Australia Geological Survey, No. E 2046, 19P.Australia, South AustraliaProspecting, Bulk Sampling, Geochemistry
DS1983-0230
1983
Ogloblina, A.I.Florovskaya, V.N., Korytov, F.YA., Ogloblina, A.I., Ramenskaya.Polycycle Aromatics in a Plutonic Lherzolite Xenolith and BasaltDoklady Academy of Science USSR, Earth Science Section., Vol. 262, No. 106, PP. 121-122.Russia, MongoliaRelated Rocks
DS1983-0488
1983
Ogloblina, A.I.Ogloblina, A.I., Rudenko, A.P., et al.Characteristics of the composition of polycyclic aromatic hydrocarbons inkimberlites.(in Russian)Doklady Academy of Sciences Akademy Nauk SSSR.(Russian), Vol. 272, No. 4, pp. 964-967RussiaBlank
DS1983-0489
1983
Ogloblina, A.I.Ogloblina, A.I., Rudenko, A.P., Kulakova, I.I., et al.Pecularities of the Composition of Polycyclic Atomatic Hydrocarbons in Kimberlites.Doklady Academy of Sciences AKAD. NAUK SSSR., Vol. 272, No. 4, PP. 964-967.RussiaMineral Chemistry
DS1984-0439
1984
Ogloblina, A.I.Kulakova, I.I., Ogloblina, A.I., et al.Polycyclic Aromatics in Accessory Minerals of Diamond and Their Possible Genesis.Doklady Academy of Science USSR, Earth Science Section., Vol. 267, No. 1-6, JUNE PP. 206-209.RussiaGenesis Pyrope, Mineral Chemistry
DS1985-0319
1985
Ogloblina, A.I.Kaminskii, F.V., Kulakova, I.I., Ogloblina, A.I.Polycyclic Aromatic Hydrocarbons in Carbonado and DiamondDoklady Academy of Sciences AKAD. NAUK SSSR., Vol. 283, No. 4, PP. 985-989.RussiaBlank
DS1985-0503
1985
Ogloblina, A.I.Ogloblina, A.I., Rudenko, A.P., Kulaskova, I.I., et al.Composition of Polycyclic Aromatics in KimberliteDoklady Academy of Science USSR, Earth Science Section., Vol. 272, No. 1-6, MARCH PP. 199-202.RussiaGeochemistry
DS1987-0328
1987
Ogloblina, A.I.Kaminskiy, F.V., Kulakova, I.I., Ogloblina, A.I.Polycyclic aromatic hydrocarbons in carbonado and diamondDoklady Academy of Sciences Acad. Svi. Ussr Earth Sci. Section, Vol. 283, No. 4, pp. 147-150RussiaGeochemistry, Diamond
DS1990-1344
1990
Ogloblina, A.I.Shepeleva, N.N., Ogloblina, A.I., Pikovskiy, Yu.I.Polycyclic aromatic hydrocarbons in carbonaceous material from the Daldyn-Alakit region, Siberian PlatformGeochemical Int, Vol. 27, No. 3, pp. 98-107RussiaKimberlite, Carbonaceous material
DS1970-0970
1974
O'gorman, J.V.O'gorman, J.V., Kitchener, J.A.The Flocculation and Dewatering of Kimberlite Clay SlimesInternational Journal of MIN. Proceedings, Vol. 1, PP. 33-49.South AfricaDiamond Mining Recovery, Kimberlite Pipes
DS201901-0050
2018
Ogorodova, L.P.Ogorodova, L.P., Gritsenko, Y.D., Vigasina, M.F., Bychkov, A.Y., Ksenofontov, D.A., Melchakova, L.V.Thermodynamic properties of natural melilites.American Mineralogist, Vol. 103, pp. 1945-1952.Mantlemineralogy

Abstract: In the present study, four samples of natural melilites were characterized using electron microprobe analysis, powder X-ray diffraction, FTIR, and Raman spectroscopy, and their thermodynamic properties were measured with a high-temperature heat-flux Tian-Calvet microcalorimeter. The enthalpies of formation from the elements were determined to be: -3796.3 ± 4.1 kJ/mol for Ca1.8Na0.2(Mg0.7Al0.2Fe2+0.1?)Si2O7, -3753.6 ± 5.2 kJ/mol for Ca1.6Na0.4(Mg0.5Al0.4Fe2+0.1?)Si2O7, -3736.4 ± 3.7 kJ/mol for Ca1.6Na0.4(Mg0.4Al0.4Fe2+0.2?)Si2O7, and -3929.2 ± 3.8 kJ/mol for Ca2(Mg0.4Al0.6)[Si1.4Al0.6O7]. Using the obtained formation enthalpies and estimated entropies, the standard Gibbs free energies of formation of these melilites were calculated. Finally, the enthalpies of the formation of the end-members of the isomorphic åkermanite-gehlenite and åkermanite-alumoåkermanite series were derived. The obtained thermodynamic properties of melilites of different compositions can be used for quantitative modeling of formation conditions of these minerals in related geological and industrial processes.
DS201801-0022
2017
Oguchi, T.Hecht, H., Oguchi, T.Global evalusation of erosion rates in relation to tectonics. Progress in Earth and Planetary Science, 7p. PdfGlobaltectonics

Abstract: Understanding the mechanisms and controlling factors of erosion rates is essential in order to sufficiently comprehend bigger processes such as landscape evolution. For decades, scientists have been researching erosion rates where one of the main objectives was to find the controlling factors. A variety of parameters have been suggested ranging from climate-related, basin morphometry and the tectonic setting of an area. This study focuses on the latter. We use previously published erosion rate data obtained mainly using 10Be and sediment yield and sediment yield data published by the United States Geological Survey. We correlate these data to tectonic-related factors, i.e., distance to tectonic plate boundary, peak ground acceleration (PGA), and fault distribution. We also examine the relationship between erosion rate and mean basin slope and find significant correlations of erosion rates with distance to tectonic plate boundary, PGA, and slope. The data are binned into high, medium, and low values of each of these parameters and grouped in all combinations. We find that groups with a combination of high PGA (>?0.2.86 g) and long distance (>?1118.69 km) or low PGA (
DS201510-1794
2015
Ogungbuyi, P.I.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
Ogungbuyi, P.I.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
DS1990-1129
1990
Oh, C.W.Oh, C.W., Liou, J.G.Metamorphic evolution of two different eclogites in the Franciscan California, United States (US)Lithos, Vol. 25, No. 1-3, November pp. 41-54CaliforniaEclogites, San Franciscan complex
DS1991-1249
1991
Oh, C.W.Oh, C.W., Liou, J.G., Maruyama, S.Low temperature eclogites and eclogitic schists in Mn-rich metabasites in Ward Creek, California: Mn and iron effects on the transition blueschist andeclogitesJournal of Petrology, Vol. 32, No. 2, April pp. 275-302CaliforniaEclogites
DS200612-1000
2006
Oh, C.W.Oh, C.W.A new concept on tectonic correlation between Korea, Chin a and Japan: histories from the late Proterozoic to Cretaceous.Gondwana Research, Vol. 9, pp. 47-61.Asia, China, Korea, JapanUHP, Dabie Sulu collision belt
DS200812-0815
2008
Oh, E.S.Oh, E.S., Slattery, J.C.Nanoscale thermodynamics of multicomponent, elastic, crystalline solids: diamond, silicon and silicon carbide.Philosophical Magazine, Vol. 88, 3, pp. 427-440.TechnologyThermometry
DS200812-1056
2008
Oh, Y.B.Shin, D.B., Oh, Y.B., Lee, M.J.Petrological and geochemical characteristics of the Hongcheon carbonatite phoscorite, Korea.Goldschmidt Conference 2008, Abstract p.A861.Asia, KoreaCarbonatite
DS201212-0584
2012
O'Hagan, S.Rice, M.D., Tierney, S., O'Hagan, S., Lyons, D., Green, M.B.Knowledge, influence and firm level change: a geographic analysis of board membership associated with Canada's growing and declining businesses.Geoforum, Vol. 43, pp. 959-968.CanadaCSR - governance
DS1989-1349
1989
O'Hanley, D.S.Schandl, E.S., O'Hanley, D.S., Wicks, F.J.Rodingites in serpentinized ultramafic rocks of the Abitibi Greenstonebelt, OntarioCanadian Mineralogist, Vol. 27, No. 4, December pp. 579-592OntarioGreenstone belt, Abitibi, ultramafics
DS1996-1049
1996
O'Hanlon, L.O'Hanlon, L.The measure of a mountain.. highest mountains.Earth, February, pp. 51-57GlobalMountains
DS2002-1173
2002
O'Hanlon, L.O'Hanlon, L.Glittering globe - could Earth be littered with diamonds in places no one's thought of looking?New Scientist, Aug. 17, pp. 48-51.GlobalDiamonds - meteoritic
DS2002-1174
2002
O'Hanlon, L.O'Hanlon, L.Glittering globe:could the earth be littered with diamonds in places no one has dreamed of looking? .. Hanlon ventures to an island paradise in search....New Scientist, August 17, pp. 48-50.Solomon IslandsSolsearch, Collerson, Zorba Mining, University of Queen
DS1988-0777
1988
Ohara, H.Yoshioka, T., Imai, O., Ohara, H., Doi, A., Fujimori, N.Thin solid films of ceramic and diamond and their applicationSurf. Coat. Technol, Vol. 36, No. 1-2, pp. 311-318GlobalDiamond applications/coatings
DS200512-0800
2004
O'Hara, B.O'Hara, B.Fort a la Corne.. the gem of Saskatchewan.Canadian Institute of Mining and Metallurgical Bulletin, Vol. 97, 1085, Dec. pp. 0-34.Canada, SaskatchewanNews item - Shore Gold
DS200512-0801
2005
O'Hara, B.O'Hara, B.Diamond rush.... with 70 companies in town and many more predicted, is Vancouver poised to become the diamond discovery capital of the country.Mining Review , Fall, pp. 9-11.CanadaNews item - list of Vancouver labs
DS200512-0802
2004
O'Hara, B.O'Hara, B.Fort a la Corne.. the gem of Saskatchewan.Canadian Institute of Mining and Metallurgy Bulletin, Vol. 97, 1084, Nov. Dec. pp. 30-34.Canada, SaskatchewanNews item - overview of current activity
DS200612-1001
2005
O'Hara, B.O'Hara, B.Diamonds on the horizon... 70 exploration companies in town.. is Vancouver poised to become the diamond discovery capital of the country?Mining Review, Fall, pp. 9-11.CanadaNews item - companies
DS1960-0383
1963
O'hara, M.J.O'hara, M.J., Mercy, E.L.P.Petrology and Petrogenesis of Some Garnetiferous PeridotitesRoyal Society. EDINBURGH EARTH SCI. SECT. Transactions, Vol. 65, PP. 251-314.South AfricaGeology, Garnets
DS1960-0579
1965
O'hara, M.J.Mercy, E.L.P., O'hara, M.J.Chemistry of Some Garnet Bearing Rocks from the South Norwegian Peridotites.Norske Geol. Tidsskr., Vol. 45, PP. 323-332.Norway, ScandinaviaGeochemistry
DS1960-0580
1965
O'hara, M.J.Mercy, E.L.P., O'hara, M.J.Olivines and Orthopyroxenes from Garnetiferous Peridotites And Related Rocks.Norske Geol. Tidsskr., Vol. 45, PP. 457-461.Norway, ScandinaviaPetrography
DS1960-0723
1966
O'hara, M.J.O'hara, M.J.Eclogite, Peridotite and Pyrope from the Navajo Counties, Arizona and new Mexico.American MINERALOGIST., Vol. 51, PP. 336-352.United States, Arizona, New Mexico, Colorado PlateauBlank
DS1960-0724
1966
O'hara, M.J.O'hara, M.J., Mercy, E.L.P.Exceptionally Calcic Pyralspite from South African Kyanite Eclogite.Nature., Vol. 212, No. 5057, PP. 68-69.South AfricaRoberts Victor Mine, Mineralogy
DS1960-0725
1966
O'hara, M.J.O'hara, M.J., Mercy, E.L.R.Peridotite and Pyrope from the Navajo Country, Arizona and New Mexico.American MINERALOGIST., Vol. 51, No. 3-4, PP. 336-352.GlobalDiatreme
DS1970-0631
1973
O'hara, M.J.Berg, G.W., O'hara, M.J.Source Mantle Rubidium and Partial Melt Composition Deduced from the Kimberlite Record.International Kimberlite Conference, ABSTRACT VOLUME, PP. 31-34.South AfricaGenesis
DS1975-0153
1975
O'hara, M.J.O'hara, M.J., Saunders, M.J., Mercy, E.L.P.Garnet Peridotite, Primary Ultrabasic Magmas and Eclogites:interpretation of Upper Mantle Processes in Kimberlite.Physics and Chemistry of the Earth., Vol. 9, PP. 571-604.South AfricaPetrology
DS1985-0283
1985
O'hara, M.J.Herzberg, C.T., O'hara, M.J.Origin of Mantle Peridotite and Komatiite by Partial MeltingGeophysical Research. LETTERS, Vol. 12, No. 9, SEPTEMBER PP. 541-544.GlobalPetrology
DS1990-1544
1990
O'Hara, M.J.Waters, F.G., Cohen, A.S., O'Nions, R.K., O'Hara, M.J.Development of Archean lithosphere deduced from chronology and isotope chemistry of Scourie DykesEarth and Planetary Science Letters, Vol. 97, No. 3/4, March pp. 241-255ScotlandUltramafic rocks, Scourie Dykes
DS1995-1377
1995
O'Hara, M.J.O'Hara, M.J.Trace element geochemical effects of integrated melt extraction and shaped melting reimesJournal of Petrology, Vol. 96, No. 4, pp. 1111-1132MantleMelt - shapes, Geochemistry
DS1996-1050
1996
O'Hara, M.J.O'Hara, M.J., Fry, N.The highly compatible trace element paradox fractional crystallizationrevisitedJournal of Petrology, Vol. 37, No. 4, Aug. 1, pp. 859-890GlobalMagma chambers, Layered intrusions
DS1996-1051
1996
O'Hara, M.J.O'Hara, M.J., Fry, N.Geochemical effects of small packet crystallization in large magma chambers-further resolutions =paradoxJournal of Petrology, Vol. 37, No. 4, Aug. 1, pp. 891-GlobalMagma chambers, Layered intrusions
DS1998-0616
1998
O'Hara, M.J.Herzberg, C., O'Hara, M.J.Phase equilibrium constraints on the origin of basalts, picrites andkomatiites.Earth Science Reviews, Vol. 44, No. 1-2, July pp. 39-79.South Africa, IcelandPeridotites, Craton, lithosphere, mantle plumes, Petrology, Picrites
DS1998-1090
1998
O'Hara, M.J.O'Hara, M.J.Volcanic plumbing and the space problem - thermal and geochemical consequence of large scale assimilation..Journal of Petrol, Vol. 39, No. 5, May pp. 1077-OceanIslands - volcanics, Geochemistry, geothermometry
DS2000-0726
2000
O'Hara, M.J.O'Hara, M.J.Flood basalts, basalt floods or topless Bushvelds: Lunar petrogenesis revisited.Journal of Petrology, Vol. 41, No. 11, Nov. pp. 1545-1651.GlobalBasalts - flood, Review
DS2002-0713
2002
O'Hara, M.J.Herzberg, C., O'Hara, M.J.Plume associated ultramafic magmas of Phanerozoic ageJournal of Petrology, Vol. 43, No. 10, Oct.pp. 1857-1884.GlobalHot spots, Magmatism
DS2003-1018
2003
O'Hara, M.J.Niu, Y., O'Hara, M.J., Pearce, J.A.Initiation of subduction zones as a consequence of lateral compositional buoyancy:Journal of Petrology, Vol. 44, 5, pp. 851-66.MantleSubduction
DS200412-1441
2003
O'Hara, M.J.Niu, Y., O'Hara, M.J., Pearce, J.A.Initiation of subduction zones as a consequence of lateral compositional buoyancy: contrast within the lithosphere: a petrologicJournal of Petrology, Vol. 44, 5, pp. 851-66.MantleSubduction
DS200612-0982
2006
O'Hara, M.J.Niu, Y., O'Hara, M.J.MORB mantle hosts the missing Eu in the continental crust.Geochimica et Cosmochimica Acta, Vol. 70, 18, p. 447. abstract only.MantleGeochemistry - Eu
DS1960-0681
1966
O'hara, N.W.Hinze, W.J., O'hara, N.W.Aeromagnetic Studies of Eastern Lake SuperiorIn: The Earth Beneath The Continents, American Geophys. Monogra, No. 10, PP. 95-110.GlobalMid-continent, Geophysics
DS1960-0869
1967
O'hara, N.W.O'hara, N.W.An Aeromagnetic and Geophysical Interpretation of the Precambrian Framework and Tectonic Structure of the Eastern Lake Superior Region.Ph.d. Thesis, East Lansing, Michigan State University, 260P.Wisconsin, MichiganMid-continent, Geophysics
DS1970-0376
1971
O'hara, N.W.O'hara, N.W.A Regional Geophysical Investigation of the Green Bay AreaProceedings 14TH. Conference GREAT LAKES RES., PP. 355-367.MichiganMid-continent
DS1970-0578
1972
O'hara, N.W.O'hara, N.W., Hinze, W.J.Basement Geology of the Lake Michigan Area from Aeromagnetic Studies.Geological Society of America (GSA) Bulletin., Vol. 83, PP. 1771-1786.Michigan, WisconsinMid-continent, Geophysics
DS1970-0800
1973
O'hara, N.W.O'hara, N.W., Wold, R.J., Hinze, W.J.Regional Gravity and Magnetic Study of Southern Lake MichigaInternational Association GREAT LAKES RESEARCH, 16TH. CONFERENCE PROCEE, PP. 431-440.MichiganMid-continent
DS1970-0802
1973
O'hara, N.W.Oray, E., Hinze, W.J., O'hara, N.W.Gravity and Magnetic Evidence for the Eastern Termination Of the Lake Superior Syncline.Geological Society of America (GSA) Bulletin., Vol. 84, PP. 2763-2780.GlobalMid-continent
DS1970-0971
1974
O'hara, N.W.O'hara, N.W., Meguid, F., Hinze, W.J.Gravity and Magnetic Observations from Lake Erie and Lake Ontario Region.Geological Society of America (GSA), Vol. 6, No. 7, P. 896, (abstract.).Michigan, OhioMid-continent
DS1975-0105
1975
O'hara, N.W.Hinze, W.J., Kellogg, R.L., O'hara, N.W.Geophysical Studies of Basement Geology of Southern Peninsula of Michigan.American Association PET. GEOL. Bulletin., Vol. 59, PP. 1562-1584.MichiganMid-continent, Geophysics
DS1975-0370
1976
O'hara, N.W.O'hara, N.W., Hinze, W.J.Deep Crustal Implications of Regional Gravity and Magnetic Data.Geological Society of America (GSA), Vol. 8, No. 4, PP. 502-503. (abstract.).GlobalMid-continent
DS1980-0264
1980
O'hara, N.W.O'hara, N.W., Hinze, W.J.Regional Basement Geology of Lake HuronGeological Society of America (GSA) Bulletin., Vol. 91, PT. 1, PP. 348-358.MichiganMid-continent
DS1981-0320
1981
O'hara, N.W.O'hara, N.W.Great Lakes Region Gravity and Magnetic Map Sequence - Michigan Basin Area.Geological Society of America (GSA), MAP AND CHART SERIES, MC-40. 1:750, 000GlobalMid-continent
DS1981-0321
1981
O'hara, N.W.O'hara, N.W.Great Lakes Region Gravity and Magnetic Map Sequence - Great Lakes Area.Geological Society of America (GSA), MAP AND CHART SERIES, MC-41. 1:750, 000GlobalMid-continent
DS1981-0322
1981
O'hara, N.W.O'hara, N.W.Great Lakes Region Gravity and Magnetic Map Sequence - Lake huron Area.Geological Society of America (GSA), MAP AND CHART SERIES, MC-39. 1:750, 000Lake HuronBlank
DS1981-0323
1981
O'hara, N.W.O'hara, N.W.Great Lakes Region Gravity and Magnetic Map Sequence - Lake michigan Area.Geological Society of America (GSA), MAP AND CHART SERIES, MC-38. 1:750, 000Lake MichiganBlank
DS1981-0324
1981
O'hara, N.W.O'hara, N.W.Great Lakes Region Gravity and Magnetic Map Sequence - Lake superior Area.Geological Society of America (GSA), MAP AND CHART SERIES, MC-37. 1:750, 000Lake SuperiorMid-continent
DS1982-0278
1982
O'hara, N.W.Hinze, W.J., Wold, R.J., O'hara, N.W.Gravity and Magnetic Anomaly Studies of Lake SuperiorGeological Society of America (GSA) MEMOIR., No. 156, PP. 203-221.Wisconsin, Minnesota, MichiganMid-continent
DS1983-0490
1983
O'hara, N.W.O'hara, N.W., Lyons, P.L.New Map Updates Gravity Dat a of the United StatesGeotimes, Vol. 28, No. 12, DECEMBER PP. 22-27.GlobalMid-continent
DS1986-0363
1986
O'Hara, N.W.Hinze, W.J., Kane, M.F., O'Hara, N.W., Reford, M.S., Tanner, J., WeberThe utility of regional gravity and magnetic anomaly mapsSociety of Exploration Geophysicists, Special Volume, 400pUnited States, CanadaGeophysics
DS2002-1175
2002
O'Hara, Y.O'Hara, Y., Stern, Ishii, Yurimoto, YamazakiPeridotites from the Mariana Trough: first look at the mantle beneath an active back-arc basin.Contribution to Mineralogy and Petrology, Vol.143,1,pp.1-18., Vol.143,1,pp.1-18.Mariana TroughPeridotites
DS2002-1176
2002
O'Hara, Y.O'Hara, Y., Stern, Ishii, Yurimoto, YamazakiPeridotites from the Mariana Trough: first look at the mantle beneath an active back-arc basin.Contribution to Mineralogy and Petrology, Vol.143,1,pp.1-18., Vol.143,1,pp.1-18.Mariana TroughPeridotites
DS1985-0002
1985
Ohashi, H.Akasaka, M., Ohashi, H.57 Iron Mossbauer Study of Synthetic Iron 3 MelilitesPhysics Chem. Minerals, Vol. 12, No. 1, PP. 13-18.GlobalExperimental Petrology
DS1975-0214
1975
Ohashi, Y.Wyatt, B., Mccallister, R.H., Boyd, F.R., Ohashi, Y.An Experimentally Produced Clinopyroxene Ilmenite IntergrowtCarnegie Institute Yearbook, FOR 1974, PP. 536-542.South AfricaNodules, Petrography
DS2002-1009
2002
Ohde, S.Mataragio, J.P., Ohde, S., Hogan, J.P.Geochemistry of PAnd a Hill carbonatites from Tanzania: implications for their origin and evolution.16th. International Conference On Basement Tectonics '02, Abstracts, 2p., 2p.TanzaniaGeochronology
DS1991-1250
1991
Ohenstetter, D.Ohenstetter, D., Watkinson, D.H., Dahl, R.Zoned hollingworthite from Two Duck Lake intrusion, Coldwell Complex, Ontario.American Mineralogist, Vol. 76, pp. 1694-1700.OntarioColdwell alkaline complex area
DS1999-0460
1999
Ohenstetter, D.McDonald, I., Ohenstetter, D.Palladium oxides in ultramafic complexes near Lavatrafo, WesternAndriemena.Mineralogical Magazine, Vol. 63, No. 3, June, pp. 345-52.MadagascarUltramafic rocks
DS201709-1984
2017
Ohenstetter, D.Feneyrol, J., Giuliani, G., Demaiffe, D., Ohenstetter, D., Fallick, A.E., Dubessy, J., Martelet, J-E., Rakotondrazafy, A.F.M., Omito, E., Ichangi, D., Nyamai, C., Wamunyu, W.Age and origin of the tsavorite and tanzanite mineralozing fluids in the Neoproterozoic Mozambique metamorphic belt.The Canadian Mineralogist, Vol. 55, pp. 763-786.Africa, Kenya, Tanzania, Madagascartanzanite

Abstract: The genetic model previously proposed for tsavorite- (and tanzanite-) bearing mineralization hosted in the Neoproterozoic Metamorphic Mozambique Belt (stretching from Kenya through Tanzania to Madagascar) is refined on the basis of new Sm-Nd age determinations and detailed Sr-O-S isotope and fluid-inclusion studies. The deposits are hosted within meta-sedimentary series composed of quartzites, graphitic gneisses, calc-silicate rocks intercalated with meta-evaporites, and marbles. Tsavorite occurs either in nodules (also called “boudins”) oriented parallel to the metamorphic foliation in all of the deposits in the metamorphic belt or in quartz veins and lenses located at the hinges of anticlinal folds (Lelatema fold belt and Ruangwa deposits, Tanzania). Gem tanzanite occurs in pockets and lenses in the Lelatema fold belt of northern Tanzania. The Sm-Nd isotopic data for tsavorites and tanzanites hosted in quartz veins and lenses from Merelani demonstrate that they formed at 600 Ma, during the retrograde metamorphic episode associated with the East African Orogeny. The tsavorites hosted in nodules do not provide reliable ages: their sedimentary protoliths had heterogeneous compositions and their Sm-Nd system was not completely rehomogenized, even at the local scale, by the fluid-absent metamorphic recrystallization. The initial 87Sr/86Sr isotopic ratios of calcite from marble and tanzanites from Merelani fit with the strontium isotopic composition of Neoproterozoic marine carbonates. Seawater sediment deposition in the Mozambique Ocean took place around 720 Ma. The quartz-zoisite O-isotopic thermometer indicates a temperature of formation for zoisite between 385 and 448 °C. The sulfur isotopic composition of pyrite (between –7.8 and –1.3‰ V-CDT) associated with tsavorite in the Lelatema fold belt deposits suggests the contribution of reduced marine sulfate. The sulfur in pyrite in the marbles was likely derived from bacterial sulfate reduction which produced H2S. Fluid inclusion data from tsavorite and tanzanite samples from the Merelani mine indicate the presence of a dominant H2S-S8±(CH4)±(N2)±(H2O)-bearing fluid. In the deposits in Kenya and Madagascar, the replacement of sulfate by tsavorite in the nodules and the boron isotopic composition of tourmaline associated with tsavorite are strong arguments in favor of the participation of evaporites in garnet formation.
DS200612-0777
2006
Ohfuji, H.Le Guillou, C., Brunet, F., Rouzand, J.N., Irifune, T., Ohfuji, H.New experimental constraints on nanodiamond formation mechanisms from carbon nanoparticles at high pressure.International Mineralogical Association 19th. General Meeting, held Kobe, Japan July 23-28 2006, Abstract p.161.TechnologyNanodiamonds
DS200812-0503
2008
Ohfuji, H.Irifune, T., Higo, Y., Inoue, T., Kono, Y., Ohfuji, H., Funakoshi, K.Sound velocities of majorite garnet and the composition of the mantle transition zone.Nature, Vol. 451, 7180, pp. 814-817.MantleGeophysics - seismics
DS201012-0311
2010
Ohfuji, H.Irifune, T., Isobe, F., Shinmei, T., Sanchira, T., Ohfuji, H., Kurio, A., Sumiya, H.Synthesis of ultrahard nano-polycrystalline diamond at high pressure and temperature using a large volume multianvil apparatus.International Mineralogical Association meeting August Budapest, abstract p. 182.TechnologyDiamond synthesis
DS201012-0547
2010
Ohfuji, H.Ohfuji, H.Influence of graphite crystallinity on the microcrystalline diamond obtained by direct conversion.International Mineralogical Association meeting August Budapest, AbstractTechnologyCrystallography
DS201012-0548
2010
Ohfuji, H.Ohfuji, H., Okimoto, S., Kunimoto, T., Irifune, T.Influence of graphite crystallinity on the microtexture of polycrystalline diamond obtained by direct conversion.International Mineralogical Association meeting August Budapest, abstract p. 182.TechnologyDiamond synthesis
DS201212-0332
2012
Ohfuji, H.Ishibashi, H., Kagi, H., Sakuai, H., Ohfuji, H., Sumino, H.Hydrous fluid as the growth media of natural polycrystalline diamond, carbonado: implication from IR spectra and microtextural observations.American Mineralogist, Vol. 97, pp. 1366-1372.Africa, Central African RepublicCarbonado
DS201312-0652
2013
Ohfuji, H.Nishi, M., Irifune, T., Ohfuji, H., Tange, Y.Intracrystalline nucleation during the post garnet transformation under large overpressure conditions in deep subducting slabs.Geophysical Research Letters, Vol. 39, 23,MantleSubduction
DS201312-0653
2013
Ohfuji, H.Nishi, M., Kubo, T., Ohfuji, H., Kato, T., Nishihara, Y., Irifune, T.Slow Si-Al interdiffusion in garnet and stagnation of subducting slabs.Earth and Planetary Science Letters, Vol. 361, pp. 44-49.MantleSubduction
DS201611-2117
2016
Ohfuji, H.Kagi, H., Zedgenizov, D.A., Ohfuji, H., Ishibashi, H.Micro- and nano-inclusions in a superdeep diamond from Sao Luiz, Brazil.Geochemistry International, Vol. 54, 10, pp. 834-838.South America, BrazilDeposit - Sao Luiz

Abstract: We report cloudy micro- and nano-inclusions in a superdeep diamond from São-Luiz, Brazil which contains inclusions of ferropericlase (Mg, Fe)O and former bridgmanite (Mg, Fe)SiO3 and ringwoodite (Mg, Fe)2SiO4. Field emission-SEM and TEM observations showed that the cloudy inclusions were composed of euhedral micro-inclusions with grain sizes ranging from tens nanometers to submicrometers. Infrared absorption spectra of the cloudy inclusions showed that water, carbonate, and silicates were not major components of these micro- and nano-inclusions and suggested that the main constituent of the inclusions was infrared-inactive. Some inclusions were suggested to contain material with lower atomic numbers than that of carbon. Mineral phase of nano- and micro-inclusions is unclear at present. Microbeam X-ray fluorescence analysis clarified that the micro-inclusions contained transition metals (Cr, Mn, Fe, Co, Ni, Cu, Zn) possibly as metallic or sulfide phases. The cloudy inclusions provide an important information on the growth environment of superdeep diamonds in the transition zone or the lower mantle.
DS201707-1322
2017
Ohfuji, H.Fei, H., Yamazaki, D., Sakurai, M., Miyajima, N., Ohfuji, H., Katsura, T., Yamamoto, T.A nearly water-saturated mantle transition zone inferred from mineral viscosity. Wadsleyite, ringwooditeScience Advances, Vol. 3, 6, 7p.Mantlewater

Abstract: An open question for solid-earth scientists is the amount of water in Earth’s interior. The uppermost mantle and lower mantle contain little water because their dominant minerals, olivine and bridgmanite, have limited water storage capacity. In contrast, the mantle transition zone (MTZ) at a depth of 410 to 660 km is considered to be a potential water reservoir because its dominant minerals, wadsleyite and ringwoodite, can contain large amounts of water [up to 3 weight % (wt %)]. However, the actual amount of water in the MTZ is unknown. Given that water incorporated into mantle minerals can lower their viscosity, we evaluate the water content of the MTZ by measuring dislocation mobility, a property that is inversely proportional to viscosity, as a function of temperature and water content in ringwoodite and bridgmanite. We find that dislocation mobility in bridgmanite is faster by two orders of magnitude than in anhydrous ringwoodite but 1.5 orders of magnitude slower than in water-saturated ringwoodite. To fit the observed mantle viscosity profiles, ringwoodite in the MTZ should contain 1 to 2 wt % water. The MTZ should thus be nearly water-saturated globally.
DS201901-0039
2018
Ohfuji, H.Gu, T., Valley, J., Kitajima, K., Spicuzza, M., Fournelle, J., Stern, R., Ohfuji, H., Wang, W.Evidence of subducted altered oceanic crust into deep mantle from inclusions of type IaB diamonds,Gems & Gemology, Sixth International Gemological Symposium Vol. 54, 3, 1p. Abstract p. 306-7.Mantlediamond inclusions

Abstract: Nitrogen is one of the most common impurities in diamond, and its aggregation styles have been used as criteria for diamond classification. Pure type IaB diamonds (with 100% nitrogen in B aggregation) are rather rare among natural diamonds. The occurrence of the B center is generally associated with high temperature and a long residence time of the host diamond, which would potentially provide information on the earth’s deep interior. Seawater circulation is the unique process that shapes the surface of our planet and potentially has a profound effect on its interior due to slab subduction. In about 50 type IaB diamonds with detectable micro-inclusions submitted to GIA for screening, we found that more than 70% of them contained a typical mineral assemblage from the sublithosphere. Jeffbenite (TAPP), majorite garnet, enstatite, and ferropericlase have been observed, which could be retrograde products of former bridgmanite. CaSiO3-walstromite with larnite and titanite is the dominant phase present in approximately 40% of all diamond samples. Direct evidence from oxygen isotope ratios measured by secondary ion mass spectrometry, or SIMS, (d18OVSMOWin the range +10.7 to +12.5‰) of CaSiO3-walstromite with coexisting larnite and titanite that retrograde from CaSiO3-perovskite suggest that hydrothermally altered oceanic basalt can subduct to depths of >410 km in the transition zone. Incorporation of materials from subducted altered oceanic crust into the deep mantle produced diamond inclusions that have both lower mantle and subduction signatures. Ca(Si,Al)O3-perovskite was observed with a high concentration of rare earth elements (>5 wt.%) that could be enriched under P-Tconditions in the lower mantle. Evidence from ringwoodite with a hydroxide bond, coexisting tuite and apatite, precipitates of an NH3phase, and cohenite with trace amounts of Cl imply that the subducted brines can potentially introduce hydrous fluid to the bottom of the transition zone. In the diamonds with subducted materials, the increasing carbon isotope ratio from the core to the rim region detected by SIMS (d13C from -5.5‰ to -4‰) suggests that an oxidized carbonate-dominated fluid was associated with recycling of the subducted hydrous material. The deep subduction played an important role in balancing redox exchange with the reduced lower mantle indicated by precipitated iron nanoparticles and coexisting hydrocarbons and carbonate phases.
DS201906-1297
2019
Ohfuji, H.Gu, T., Ohfuji, H., Wang, W.Origin of milky optical features in type 1aB diamonds: dislocations, nano-inclusions, and polycrystalline diamond.American Mineralogist, Vol. 104, pp. 652-658.Globaldiamond morphology
DS201906-1315
2019
Ohfuji, H.Litasov, K.D., Kagi, H., Voropaev, S.A., Hirata, T., Ohfuji, H., Ishibashi., Makino, Y., Bekker, T.B., Sevastyanov, V.S., Afanasiev,V.P., Pokhilenko, N.P.Comparison of enigmatic diamonds from the Tolbachik arc volcano ( Kamchatka) and Tibetan ophiolites: assessing the role of contamination by synthetic materials. Gondwana Research, in press available 38p.Russia, Asia, Tibetdeposit - Tolbachik

Abstract: The enigmatic appearance of cuboctahedral diamonds in ophiolitic and arc volcanic rocks with morphology and infrared characteristics similar to synthetic diamonds that were grown from metal solvent requires a critical reappraisal. We have studied 15 diamond crystals and fragments from Tolbachik volcano lava flows, using Fourier transform infrared spectrometry (FTIR), transmission electron microscopy (TEM), synchrotron X-ray fluorescence (SRXRF) and laser ablation inductively coupled plasma mass-spectrometry (LA-ICP-MS). FTIR spectra of Tolbachik diamonds correspond to typical type Ib patterns of synthetic diamonds. In TEM films prepared using focused ion beam technique, we find Mn-Ni and Mn-Si inclusions in Tolbachik diamonds. SRXRF spectra indicate the presence of Fe-Ni and Fe-Ni-Mn inclusions with Cr, Ti, Cu, and Zn impurities. LA-ICP-MS data show variable but significantly elevated concentrations of Mn, Fe, Ni, and Cu reaching up to 70?ppm. These transition metal concentration levels are comparable with those determined by LA-ICP-MS for similar diamonds from Tibetan ophiolites. Mn-Ni (+Fe) solvent was widely used to produce industrial synthetic diamonds in the former USSR and Russia with very similar proportions of these metals. Hence, it appears highly probable that the cuboctahedral diamonds recovered from Kamchatka arc volcanic rocks represent contamination and are likely derived from drilling tools or other hard instruments. Kinetic data on diamond dissolution in basaltic magma or in fluid phase demonstrate that diamond does not form under the pressures and temperature conditions prevalent within the magmatic system beneath the modern-day Klyuchevskoy group of arc volcanoes. We also considered reference data for inclusions in ophiolitic diamonds and compared them with the composition of solvent used in industrial diamond synthesis in China. The similar inclusion chemistry close to Ni70Mn25Co5 for ophiolitic and synthetic Chinese diamonds scrutinized here suggests that most diamonds recovered from Tibetan and other ophiolites are not natural but instead have a synthetic origin. In order to mitigate further dubious reports of diamonds from unconventional tectonic settings and source rocks, we propose a set of discrimination criteria to better distinguish natural cuboctahedral diamonds from those produced synthetically in industrial environments and found as contaminants in mantle- and crust-derived rocks.
DS201907-1560
2019
Ohfuji, H.Martirosyan, N.S., Litasov, K.D., Lobanov, S.S., Goncharov, A.F., Shatskiy, A., Ohfuji, H., Prakapenka, V.The Mg carbonate Fe interaction: implication for the fate of subducted carbonates and formation of diamond in the lower mantle.Geoscience Frontiers, Vol. 10, pp. 1449-1458.Mantlecarbon cycle

Abstract: The fate of subducted carbonates in the lower mantle and at the core-mantle boundary was modelled via experiments in the MgCO3-Fe0 system at 70-150 GPa and 800-2600 K in a laser-heated diamond anvil cell. Using in situ synchrotron X-ray diffraction and ex situ transmission electron microscopy we show that the reduction of Mg-carbonate can be exemplified by: 6MgCO3 + 19Fe = 8FeO +10(Mg0.6Fe0.4)O + Fe7C3 + 3C. The presented results suggest that the interaction of carbonates with Fe0 or Fe0-bearing rocks can produce Fe-carbide and diamond, which can accumulate in the D’’ region, depending on its carbon to Fe ratio. Due to the sluggish kinetics of the transformation, diamond can remain metastable at the core-mantle boundary (CMB) unless it is in a direct contact with Fe-metal. In addition, it can be remobilized by redox melting accompanying the generation of mantle plumes.
DS202008-1428
2020
Ohfuji, H.Nishiyama, T., Ohfuji, H., Fukuba, K., Terauchi, M., Nishi, U., Harada, K., Unoki, K., Moribe, Y., Yoshiasa, A., Ishimaru, S., Mori, Y., Shigeno, M., Arai, S.Microdiamond in a low grade metapelite from a Cretaceous subduction complex, western Kyushu, Japan. ( UHP) Nishisonogi unitNature Scientific Reports, Vol. 10, 11645 11p. PdfAsia, Japanmicrodiamond

Abstract: Microdiamonds in metamorphic rocks are a signature of ultrahigh-pressure (UHP) metamorphism that occurs mostly at continental collision zones. Most UHP minerals, except coesite and microdiamond, have been partially or completely retrogressed during exhumation; therefore, the discovery of coesite and microdiamond is crucial to identify UHP metamorphism and to understand the tectonic history of metamorphic rocks. Microdiamonds typically occur as inclusions in minerals such as garnet. Here we report the discovery of microdiamond aggregates in the matrix of a metapelite from the Nishisonogi unit, Nagasaki Metamorphic Complex, western Kyushu, Japan. The Nishisonogi unit represents a Cretaceous subduction complex which has been considered as an epidote-blueschist subfacies metamorphic unit, and the metapelite is a member of a serpentinite mélange in the Nishisonogi unit. The temperature condition for the Nishisonogi unit is 450 °C, based on the Raman micro-spectroscopy of graphite. The coexistence of microdiamond and Mg-carbonates suggests the precipitation of microdiamond from C-O-H fluid under pressures higher than 2.8 GPa. This is the first report of metamorphic microdiamond from Japan, which reveals the hidden UHP history of the Nishisonogi unit. The tectonic evolution of Kyushu in the Japanese Archipelago should be reconsidered based on this finding.
DS1860-1015
1898
Ohio State JournalOhio State Journal A Rough DiamondOhio State Journal, Nov. 27TH.United States, Ohio, Great LakesDiamond Occurrence
DS201412-0645
2014
Ohira, I.Ohira, I., Ohtani, E., Sakai, T., Miyahara, M., Hirao, N., Ohishi, Y., Nishijima, M.Stability of a hydrous delta phase AlOOH-MgSiO2(OH)2, and a mechanism for water transport into the base of lower mantle.Earth and Planetary Science Letters, Vol. 401, pp. 12-17.MantleWater
DS200412-0881
2003
Ohishi, Y.Isshiki, E., Irifune, T., Hiropse, K., Ono, S., Ohishi, Y., Watanuki, T., Nishibori, E., Takat, M., Sakata, M.Stability of magnesite and its high pressure form in the lowermost mantle.Nature, No. 6969, pp. 60-62.MantleUHP
DS200412-1381
2004
Ohishi, Y.Murakami, M., Hirose, K., Kawamura, K., Sata, N., Ohishi, Y.Phase transition of MgSiO3 perovskite in the deep lower mantle.Lithos, ABSTRACTS only, Vol. 73, p. S78. abstractMantleSeismic discontinuity
DS200412-2075
2004
Ohishi, Y.Walter, M.J., Kubo, A., Yoshino, T., Brodholt, J., Koga, K.T., Ohishi, Y.Phase relations and equation of state aluminous Mg silicate perovskite and implications for Earth's lower mantle.Earth and Planetary Science Letters, Vol. 222, 2, pp. 501-516.MantlePerovskite
DS200512-0436
2005
Ohishi, Y.Hirose, K., Takafuji, N., Sata, N., Ohishi, Y.Phase transition and density of subducted MORB crust in the lower mantle.Earth and Planetary Science Letters, Vol. 237, 1-2, Aug, 30, pp. 239-251.MantleMineral chemistry, subduction
DS200512-0810
2005
Ohishi, Y.Ono, S., Ohishi, Y., Isshiki, M., Watanuki, T.In situ x-ray observations of phase assemblages in peridotite and basalt compositions at lower mantle conditions: implications for density of subducted...Journal of Geophysical Research, Vol. 110, B2, Feb. 15, dx.doi.org/10.1029/2004 JB003196MantleSubduction - oceanic plate
DS200712-0763
2007
Ohishi, Y.Murkami, M., Sinogeikin, S.V., Bass, J.D., Sata, N., Ohishi, Y., Hirose, K.Sound velocity of MgSiO3 post perovskite phase: a constraint on the D' discontinuity.Earth and Planetary Science Letters, Vol. 259, 1-2, July 15, pp. 18-23.MantleDiscontinuity
DS200812-0817
2008
Ohishi, Y.Ohta, K., Hirose, K., Lay, T., Sata, N., Ohishi, Y.Phase transitions in pyrolite and MORB at lowermost mantle conditions: implications for a MORB rich pile above the core-mantle boundary.Earth and Planetary Science Letters, Vol. 267, 1-2, pp.107-117.MantlePetrology
DS200912-0695
2008
Ohishi, Y.Sinmyo, R., Ozawa, H., Jirose, K., Yasuhara, A., Endo, N., Sata, N., Ohishi, Y.Ferric iron content in (Mg,Fe) SiO3 perovskite and post-perocskite at deep lower mantle conditions.American Mineralogist, Vol. 93, 11/12 pp. 1899-1902.MantlePerovskite
DS201112-0969
2011
Ohishi, Y.Sinmyo, R., Hirose, K., Muto, S., Ohishi, Y., Yasuhara, A.The valence state and partitioning of iron in the Earth's lowermost mantle.Journal of Geophysical Research, Vol. 116, B7, B07205.MantleChemistry
DS201212-0385
2012
Ohishi, Y.Kudo, Y., Hirose, K.,Murakami, M., Asahara, Y., Ozawa, H., Ohishi, Y., Hirao, N.Sound velocity measurements of CaSiO3 perovskite to 133 Gpa an implications for lowermost mantle seismic anomalies.Earth and Planetary Science Letters, Vol. 349-350 pp. 1-7.MantlePerovskite
DS201212-0503
2012
Ohishi, Y.Murakami, M., Ohishi, Y., Hirao, N., Hirose, K.A perovskite lower mantle inferred from high pressure, high temperature sound velocity data.Journal of the Geological Society of India, Vol. 80, 1, p. 147. Brief reviewMantlePerovskite
DS201212-0504
2012
Ohishi, Y.Murakami, M., Ohishi, Y., Hirao, N., Hirose, K.A perovskite lower mantle inferred from high pressure, high temperature sound velocity data.Nature, Vol. 485, May 3, pp. 90-94.MantlePerovskite
DS201212-0717
2012
Ohishi, Y.Tange, Y., Kuwayma, Y., Irifune, T., Funakoshi, K-I., Ohishi, Y.P-V-T equation of state of MgSiO3 perovskite based on the MgO pressure scale: a comprehensive reference for mineralogy of the lower mantle.Journal of Geophysical Research, Vol. 117, B6, B06201MantlePerovskite
DS201312-0656
2013
Ohishi, Y.Noguchi, M., Komabayashi, T., Hirose, K., Ohishi, Y.High-temperature compression experiments of CaSiO3 perovskite to lowermost mantle conditions and its thermal equation of state.Physics and Chemistry of Minerals, Vol. 40, pp. 81-91.MantleGeothermometry
DS201412-0542
2014
Ohishi, Y.Maeda, F., Ohtani, E., Kamada, S., Sakamaki, T., Ohishi, Y., Hirao, N.The reactions in the MgCO3-SiO2 system in the slabs subducted into the lower mantle and formation of deep diamond.V.S. Sobolev Institute of Geology and Mineralogy Siberian Branch Russian Academy of Sciences International Symposium Advances in high pressure research: breaking scales and horizons ( Courtesy of N. Poikilenko), Held Sept. 22-26, 1p. AbstractSouth America, BrazilCarbon
DS201412-0635
2014
Ohishi, Y.Nomura, R., Uesugi, K., Ohishi, Y., Tsuchiyama, A., Miyake, A., Ueno, Y.Low core mantle boundary temperature inferred from the solidus of pyrolite.Science, Vol. 343, 6170 pp. 522-525.MantleMelting
DS201412-0645
2014
Ohishi, Y.Ohira, I., Ohtani, E., Sakai, T., Miyahara, M., Hirao, N., Ohishi, Y., Nishijima, M.Stability of a hydrous delta phase AlOOH-MgSiO2(OH)2, and a mechanism for water transport into the base of lower mantle.Earth and Planetary Science Letters, Vol. 401, pp. 12-17.MantleWater
DS201412-0646
2014
Ohishi, Y.Ohta, K., Fujino, K., Kuwayama, Y., Kondo, T., Shimizu, K., Ohishi, Y.Highly conductive iron rich (Mg, Fe) O magnesiowustite and its stability in the Earth's lower mantle.Journal of Geophysical Research, Vol. 119, no. 6, pp. 4656-4665.MantleMineralogy
DS201412-0921
2014
Ohishi, Y.Tateno, S., Hrose, K., Ohishi, Y.Melting experiments on peridotite to lowermost mantle conditions.Journal of Geophysical Research, Vol. 119, no. 6, pp. 4684-4694.MantleMelting
DS201412-0922
2013
Ohishi, Y.Tatsumi, Y., Suzuki, T., Ozawa, H., Hirose, K., Hanyu, T., Ohishi, Y.Accumulation of 'anti-continent' at the base of the mantle and its recycling in mantle plumes.Geochimica et Cosmochimica Acta, in press availableMantleD layer
DS201504-0225
2015
Ohishi, Y.Tateno, S., Kuwayama, Y., Hirose, K., Ohishi, Y.The structure of Fe-Si alloy in Earth's inner core.Earth and Planetary Science Letters, Vol. 418, pp. 11-18.MantleCore
DS201704-0638
2017
Ohishi, Y.Maeda, F., Ohtani, E., Kamada, S., Sakamaki, T., Hirao, N., Ohishi, Y.Diamond formation in the deep lower mantle: a high pressure reaction of MgCO3 and SiO2.Nature Scientific reports, Jan. 13, 7p. PdfMantleDiamond, genesis

Abstract: Diamond is an evidence for carbon existing in the deep Earth. Some diamonds are considered to have originated at various depth ranges from the mantle transition zone to the lower mantle. These diamonds are expected to carry significant information about the deep Earth. Here, we determined the phase relations in the MgCO3-SiO2 system up to 152?GPa and 3,100?K using a double sided laser-heated diamond anvil cell combined with in situ synchrotron X-ray diffraction. MgCO3 transforms from magnesite to the high-pressure polymorph of MgCO3, phase II, above 80?GPa. A reaction between MgCO3 phase II and SiO2 (CaCl2-type SiO2 or seifertite) to form diamond and MgSiO3 (bridgmanite or post-perovsktite) was identified in the deep lower mantle conditions. These observations suggested that the reaction of the MgCO3 phase II with SiO2 causes formation of super-deep diamond in cold slabs descending into the deep lower mantle.
DS201704-0643
2017
Ohishi, Y.Ohta, K., Yagi, T., Hirose, K., Ohishi, Y.Thermal conductivity of ferropericlase in the Earths's lower mantle.Earth and Planetary Science Letters, Vol. 465, pp. 29-37.MantleGeothermometry

Abstract: (Mg,?Fe)O ferropericlase (Fp) is one of the important minerals comprising Earth's lower mantle, and its thermal conductivity could be strongly influenced by the iron content and its spin state. We examined the lattice thermal conductivity of (Mg,?Fe)O Fp containing 19 mol% iron up to 111 GPa and 300 K by means of the pulsed light heating thermoreflectance technique in a diamond anvil cell. We confirmed a strong reduction in the lattice thermal conductivity of Fp due to iron substitution as reported in previous studies. Our results also show that iron spin crossover in Fp reduces its lattice thermal conductivity as well as its radiative conduction. We also measured the electrical conductivity of an identical Fp sample up to 140 GPa and 2730 K, and found that Fp remained an insulator throughout the experimental conditions, indicating the electronic thermal conduction in Fp is negligible. Because of the effects of strong iron impurity scattering and spin crossover, the total thermal conductivity of Fp at the core-mantle boundary conditions is much smaller than that of bridgmanite (Bdg). Our findings indicate that Bdg (and post-perovskite) is the best heat conductor in the Earth's lower mantle, and distribution of iron and its valence state among the lower mantle minerals are key factors to control the lower mantle thermal conductivity.
DS202009-1649
2020
Ohishi, Y.Okuda, Y., Ohta, K., Haseawa, A., Yagi, T., Hirose, K., Kawaguchi, S.I., Ohishi, Y.Thermal conductivity of Fe bearing post- perovskite in the Earth's lowermost mantle.Earth and Planetary Science Letters, Vol. 547, 9p. PdfMantleperovskite

Abstract: The thermal conductivity of post-perovskite (ppv), the highest-pressure polymorph of MgSiO3 in the Earth's mantle, is one of the most important transport properties for providing better constraints on the temperature profile and dynamics at the core-mantle boundary (CMB). Incorporation of Fe into ppv can affect its conductivity, which has never been experimentally investigated. Here we determined the lattice thermal conductivities of ppv containing 3 mol% and 10 mol% of Fe at high P-T conditions - of pressures up to 149 GPa and 177 GPa, respectively, and temperatures up to 1560 K - by means of the recently developed pulsed light heating thermoreflectance technique combining continuous wave heating lasers. We found that the incorporation of Fe into ppv moderately reduces its lattice thermal conductivity as it increases the Fe content. The bulk conductivity of ppv dominant pyrolite is estimated as 1.5 times higher than that of pyrolite consisting of bridgmanite and ferropericlase in the lower mantle, which agrees with the traditional view that ppv acts as a better heat conductor than bridgmanite in the Earth's lowermost mantle.
DS200812-0621
2008
Ohisi, Y.Kuwayama, Y., Horise, K., Sata, N., Ohisi, Y.Phase relations of iron and iron-nickel alloys up to 300 GPa:implications for composition and structure of the Earth's inner core.Earth and Planetary Science Letters, Vol. 273, 3-4 pp. 379-385.MantleCore, chemistry
DS201312-0462
2013
Ohisi, Y.Kato, C., Hirose, K., Kombayashi, T., Ozawa, H., Ohisi, Y.NAL phase in K rich portions of the lower Mantle.Geophysical Research Letters, Vol. 40, 19, pp. 5085-5088.MantleAlkalic
DS1999-0521
1999
Ohlander, B.Ohlander, B., Wikstrom, A.The Archean Proterozooic paleoboundary in the Lulea area, northern Sweden:field and isotope geochemistryPrecambrian Research, Vol. 96, 3-4, July pp, 228-44.SwedenTerrane boundary, Geochronology
DS2002-0791
2002
Ohlander, B.Juhlin, C., Elming, S.A., Mellqvist, C., Ohlander, B., Weihed, P., Wikstrom, A.Crustal refectivity near Archean Proterozoic boundary in northern Sweden andGeophysical Journal International, Vol.150,1,pp.180-197.SwedenGeophysics - seismics, Boundary
DS1950-0292
1956
Ohle, E.L.Ohle, E.L., Brown, J.S.Geologic Problems in Southeast Missouri Lead DistrictGeological Society of America (GSA) Bulletin., Vol. 65, PP. 201-221.GlobalKimberlite, Central States
DS2002-1177
2002
Ohlmacher, G.C.Ohlmacher, G.C., Berendsen, P.Relationship between surficial structures and basement faults associated with the Midcontinent Rift, USA.16th. International Conference On Basement Tectonics '02, Abstracts, 2p., 2p.KansasTectonics
DS1975-0371
1976
Ohly, F.Ohly, F.Diamant und BocksblutUnknown, GlobalKimberlite, Kimberley, Janlib, Traveloque
DS200612-0626
2006
Ohmoto, H.Ishihara, S., Ohmoto, H., Anhaeusser, C.R., Imai, A., Robb, L.J.Discovery of the oldest oxidized granitoids in the Kaapvaal Craton and its implications for the redox evolution of early Earth.Geological Society of America Memoir, No. 198, pp. 67-80.Africa, South AfricaRedox
DS1992-1134
1992
Ohnenstetter, D.Ohnenstetter, D., Brown, W.L.Overgrowth textures, disequilibrium zoning and cooling history of a glassy four pyroxene boninite dyke from New CaledoniaJournal of Petrology, Vol. 33, No. 1, February pp. 231-?New CaledoniaBoninite, Petrology
DS1993-1156
1993
Ohnenstetter, D.Ohnenstetter, D.International symposium on mineralization related to mafic and ultramafic rocks with a special session on alkaline and carbonatitic magmatism and associated minCrscm-cnrs, To Be Held September 1-3, Orleans France, FranceSymposium September 1-3, 1993, Alkaline rocks
DS1993-1319
1993
Ohnenstetter, D.Rohon, M.-L., Vialette, Y., Clar, T., Roger, G., Ohnenstetter, D., Vidal, Ph.Aphebian mafic-ultramafic magmatism in the Labrador trough (New Quebec):its age and the nature of its mantle source.Canadian Journal of Earth Sciences, Vol. 30, No. 8, August pp. 1582-1593.QuebecCrustal contamination, Ultramafics
DS1994-1300
1994
Ohnenstetter, D.Ohnenstetter, D., Moreau, C., Demaiffe, D., Robineau, B.The Los Archipelago nepheline syenite ring structure: a magmatic marker Of the evolution of central Atlantic...#1Geological Association of Canada (GAC) Abstract Volume, Vol. 19, p.GlobalAlkaline rocks, Los Archipelago
DS1996-0991
1996
Ohnenstetter, D.Moreau, C., Ohnenstetter, D., Demaiffe, D., Robineau, B.The Los Archipelago nepheline syenite ring structure: a magmatic marker Of the evolution of central Atlantic #2Canadian Mineralogist, Vol. 34, pt. 2, April pp. 281-301.GlobalNepheline syenite
DS1996-1052
1996
Ohnenstetter, D.Ohnenstetter, D., Browm\n, W.L.Compositional variation and primary water contents of differentiated interstitial and included glasses in boninites.Contributions to Mineralogy and Petrology, Vol. 123, pp. 117-137.New CaledoniaBoninites, Glasses
DS1997-1205
1997
Ohnenstetter, D.Verhulst, A., Demaiffe, D., Ohnenstetter, D., Blanc, Ph.Cathodluminescence petrography of carbonatites and associated alkaline silicate rocks from Kola Pen.Geological Association of Canada (GAC) Abstracts, POSTER.Russia, Kola PeninsulaCarbonatite
DS2000-0727
2000
Ohnenstetter, D.Ohnenstetter, D., Verhulst, A., et al.Cathodluminescence study of the carbonatite suites of the Kola Peninsula (Russia).Igc 30th. Brasil, Aug. abstract only 1p.Russia, Kola PeninsulaCarbonatite
DS200912-0154
2009
Ohnenstetter, D.Dauphas, N., Craddock, P.R., Asimow, P.D., Bennett, V.C., Nutman, A.P., Ohnenstetter, D.Iron isotopes may reveal the redox conditions of mantle melting from Archean to present.Earth and Planetary Science Letters, Vol. 288, 1-2, pp. 255-267.MantleRedox
DS201012-0326
2010
Ohnenstetter, D.Johan, Z., Ohnenstetter, D.Zincochromite from the Guaniamo River Diamondiferous placers, Venezuela: evidence of its metasomatic origin.Canadian Mineralogist, Vol. 48, 2, pp. 361-374.South America, VenezuelaMineralogy
DS201212-0691
2012
Ohnenstetter, D.Solovova, I.P., Ohnenstetter, D., Girnis, A.V.Melt inclusions in olivine from boninites of New Caledonia: postentrapment melt modification and estimation of primary magma compositions.Petrology, Vol. 20, 6, pp. 529-544.AsiaBoninites
DS201312-0204
2013
Ohnenstetter, D.Demaiffe, D., Wiszniewska, J., Krzeminska, E., Williams, I.S., Stein, H., Brassinnes, S., Ohnenstetter, D., Deloule, E.A hidden alkaline and carbonatite province of Early Carboniferous age in northeast Poland: zircon U-Pb and pyrrhotite Re-Os geochronology.Journal of Geology, Vol. 121, 1, pp. 91-104.Europe, PolandCarbonatite
DS201412-0321
2014
Ohnenstetter, D.Groulier, P.A., Andre-Mayer, A.S., Ohnenstetter, D., Zeh, A., Moukhsil, A., Solgadi, F., El Basbas, A.Petrology, geochemistry and age of the Crevier alkaline intrusion.GAC-MAC Annual Meeting May, abstract 1p.Canada, QuebecAlkalic
DS201505-0235
2015
Ohnenstetter, D.Giuliani, G.,Pivin, M., Fallick, A.E., Ohnenstetter, D., Song, Y., Demaiffe, D.Geochemical and oxygen isotope signatures of mantle corundum megacrysts from the Mbuji-Mayi kimberlite, Democratic Republic of Congo and the Changle alkali basalt, China.Comptes Rendus Geoscience, Vol. 347, 1, pp. 24-34.Africa, Democratic Republic of Congo, ChinaDeposit - Mbuji-Mayi
DS201512-1971
2015
Ohnenstetter, D.Solgadi, F., Groulier, P.A, Moukhsil, A., Ohnenstetter, D., Andre-Mayer, A.S., Zeh, A.Nb-Ta-REE mineralization associated with the Crevier alkaline intrusion.Symposium on critical and strategic materials, British Columbia Geological Survey Paper 2015-3, held Nov. 13-14, pp. 69-74.Canada, QuebecAlkalic

Abstract: The Crevier alkaline intrusion is in the Grenville Province, north of the Lac Saint-Jean region of Québec (Fig. 1). It covers ~25 km2 (Bergeron, 1980) and intrudes charnockitic suites in the allochthon belt defi ned by Rivers et al. (1989). This intrusion has a U-Pb zircon age of 957.5 ± 2.9 Ma (Groulier et al., 2014) and is oriented N320°, along the axis of crustal weakness known as the Waswanipi-Saguenay corridor (Bernier and Moorhead, 2000). This corridor is related to the Saguenay graben, which hosts the Saint-Honoré (Niobec) Nb-Ta-REE deposit and Montviel REE deposit. The age of the Saint-Honoré carbonatite was estimated at 584 to 650 Ma (K-Ar whole rock; Vallée and Dubuc, 1970; Boily and Gosselin, 2004). The Montviel intrusion has a U-Pb zircon age of 1894 ± 3.5 Ma (David et al., 2006; Goutier, 2006). These crystallization ages are very different and cannot be related to a single event for the injection of alkaline intrusions. As mapped by Bergeron (1980), the Crevier alkaline intrusion is broadly composed of syenite and carbonatite rocks (Fig. 2). The Nb- Ta mineralization consists of pyrochlore hosted by a nepheline syenite dike swarm in the centre of the intrusion. The highest REE concentrations, up to 729 ppm La and 1465 ppm Ce, are at the edge of the Crevier alkaline intrusion (Niotaz sud showing; Fig. 2).
DS1989-1146
1989
Ohnenstetter, D.R.Ohnenstetter, D.R., Brown, W.L.Disequilibrium crystallization in a bonninite from New CaledoniaGeological Association of Canada (GAC) Annual Meeting Program Abstracts, Vol. 14, p. A22. (abstract.)New CaledoniaBonninite
DS200412-1461
2004
Ohnisi, N.Ohtaka, O., Shimono, M., Ohnisi, N., Fukui, H., Takebe, H., Arima, H., Yamanaka, T.,Kikegawa, T., Kume, S.HIP production of a diamond/ SiC composite and application to high pressure anvils.Physics of the Earth and Planetary Interiors, Vol. 143-144, pp. 587-591.TechnologyUHP
DS1991-0651
1991
Ohr, M.Halliday, A.N., Ohr, M., Mezger, K., Chesley, J.T., Nakai, S.Recent developments in dating ancient crustal fluid flowReviews of Geophysics, Vol. 29, No. 4, November pp. 577-584MantleModel -fluid flow, Geochronology
DS1989-0744
1989
Ohsawa, T.Kanda, H., Ohsawa, T., Fukunaga, O., Sunagawa, I.Effect of solvent metals upon the morphology of synthetic diamonds #1Journal of Crystal Growth, Vol. 94, pp. 115-124GlobalDiamond synthesis, Diamond morphology
DS2003-0624
2003
Ohsumi, K.Ishida, H., Ogasawara, Y., Ohsumi, K., Saito, A.Two stage growth of microdiamond in UHP dolomite marble from Kokechtav MassifJournal of Metamorphic Geology, Vol. 21, 6, pp. 515-22.Russia, KazakhstanMicrodiamonds - morphology
DS200412-0876
2003
Ohsumi, K.Ishida, H., Ogasawara, Y., Ohsumi, K., Saito, A.Two stage growth of microdiamond in UHP dolomite marble from Kokechtav Massif, Kazakhstan.Journal of Metamorphic Geology, Vol. 21, 6, pp. 515-22.Russia, KazakhstanMicrodiamonds - morphology
DS200912-0545
2009
Ohta, A.Odake, S., Kagi, H., Arakawa, M., Ohta, A., Harte, B.Oxidation state of chromium in ferropericlese inclusions in lower mantle diamonds determined with micro-XANES measurements.Goldschmidt Conference 2009, p. A962 Abstract.MantleDiamond inclusions
DS200812-0816
2008
Ohta, K.Ohta, K.The electrical conductivity of post-perovskite in Earth's D' layer.Science, Vol. 320, no. 5872, pp. 89-90.MantleGeophysics - perovskite
DS200812-0817
2008
Ohta, K.Ohta, K., Hirose, K., Lay, T., Sata, N., Ohishi, Y.Phase transitions in pyrolite and MORB at lowermost mantle conditions: implications for a MORB rich pile above the core-mantle boundary.Earth and Planetary Science Letters, Vol. 267, 1-2, pp.107-117.MantlePetrology
DS201412-0403
2014
Ohta, K.Imada, S., Ohta, K., Yagi, T., Hirose, K., Yoshida, H., Nagahara, H.Measurements of lattice thermal conductivity of MgO to core-mantle boundary.Geophysical Research Letters, Vol. 41, 13, pp. 4542-4547.MantleGeothermometry
DS201412-0646
2014
Ohta, K.Ohta, K., Fujino, K., Kuwayama, Y., Kondo, T., Shimizu, K., Ohishi, Y.Highly conductive iron rich (Mg, Fe) O magnesiowustite and its stability in the Earth's lower mantle.Journal of Geophysical Research, Vol. 119, no. 6, pp. 4656-4665.MantleMineralogy
DS201704-0643
2017
Ohta, K.Ohta, K., Yagi, T., Hirose, K., Ohishi, Y.Thermal conductivity of ferropericlase in the Earths's lower mantle.Earth and Planetary Science Letters, Vol. 465, pp. 29-37.MantleGeothermometry

Abstract: (Mg,?Fe)O ferropericlase (Fp) is one of the important minerals comprising Earth's lower mantle, and its thermal conductivity could be strongly influenced by the iron content and its spin state. We examined the lattice thermal conductivity of (Mg,?Fe)O Fp containing 19 mol% iron up to 111 GPa and 300 K by means of the pulsed light heating thermoreflectance technique in a diamond anvil cell. We confirmed a strong reduction in the lattice thermal conductivity of Fp due to iron substitution as reported in previous studies. Our results also show that iron spin crossover in Fp reduces its lattice thermal conductivity as well as its radiative conduction. We also measured the electrical conductivity of an identical Fp sample up to 140 GPa and 2730 K, and found that Fp remained an insulator throughout the experimental conditions, indicating the electronic thermal conduction in Fp is negligible. Because of the effects of strong iron impurity scattering and spin crossover, the total thermal conductivity of Fp at the core-mantle boundary conditions is much smaller than that of bridgmanite (Bdg). Our findings indicate that Bdg (and post-perovskite) is the best heat conductor in the Earth's lower mantle, and distribution of iron and its valence state among the lower mantle minerals are key factors to control the lower mantle thermal conductivity.
DS202009-1649
2020
Ohta, K.Okuda, Y., Ohta, K., Haseawa, A., Yagi, T., Hirose, K., Kawaguchi, S.I., Ohishi, Y.Thermal conductivity of Fe bearing post- perovskite in the Earth's lowermost mantle.Earth and Planetary Science Letters, Vol. 547, 9p. PdfMantleperovskite

Abstract: The thermal conductivity of post-perovskite (ppv), the highest-pressure polymorph of MgSiO3 in the Earth's mantle, is one of the most important transport properties for providing better constraints on the temperature profile and dynamics at the core-mantle boundary (CMB). Incorporation of Fe into ppv can affect its conductivity, which has never been experimentally investigated. Here we determined the lattice thermal conductivities of ppv containing 3 mol% and 10 mol% of Fe at high P-T conditions - of pressures up to 149 GPa and 177 GPa, respectively, and temperatures up to 1560 K - by means of the recently developed pulsed light heating thermoreflectance technique combining continuous wave heating lasers. We found that the incorporation of Fe into ppv moderately reduces its lattice thermal conductivity as it increases the Fe content. The bulk conductivity of ppv dominant pyrolite is estimated as 1.5 times higher than that of pyrolite consisting of bridgmanite and ferropericlase in the lower mantle, which agrees with the traditional view that ppv acts as a better heat conductor than bridgmanite in the Earth's lowermost mantle.
DS2002-0813
2002
Ohta, M.Kataayama, I., Ohta, M., Ogasawara, Y.Phengite exsolution in diopside in diamond bearing marble from Kumdy KolFrontiers Science Series, University Academy Press, Vol. 38, pp. 181-190.ChinaPetrology
DS2002-0814
2002
Ohta, M.Katayama, I., Ohta, M., Ogasawara, Y.Mineral inclusions in zircon from diamond bearing marble in the Kokchetav massif, northern Kazakhstan.European Journal of Mineralogy, Vol. 14, No. 6, pp. 1103-1108.Russia, KazakhstanDiamond - inclusions
DS2002-1172
2002
Ohta, M.Ogasawara, Y., Ohta, M., Fukasawa, K., Katayama, I., Maruyama, S.Petrology of diamond bearing dolomite marble from Kumdy KolFrontiers Science Series, University Academy Press, Vol. 38, pp. 191-212.ChinaPetrology
DS2003-1028
2003
Ohta, M.Ohta, M., Mock, T., Ogasawara, Y., Rumble, D.Oxygen, carbon, and strontium isotope geochemistry of diamond bearing carbonateLithos, Vol. 70, 3-4, pp. 77-90.Russia, KazakhstanGeochemistry
DS200412-0959
2002
Ohta, M.Kataayama, I., Ohta, M., Ogasawara, Y.Phengite exsolution in diopside in diamond bearing marble from Kumdy Kol.Frontiers Science Series, University Academy Press, Vol. 38, pp. 181-190.ChinaPetrology
DS200412-1458
2002
Ohta, M.Ogasawara, Y., Ohta, M., Fukasawa, K., Katayama, I., Maruyama, S.Petrology of diamond bearing dolomite marble from Kumdy Kol.Frontiers Science Series, University Academy Press, Vol. 38, pp. 191-212.ChinaPetrology
DS200412-1460
2003
Ohta, M.Ohta, M., Mock, T., Ogasawara, Y., Rumble, D.Oxygen, carbon, and strontium isotope geochemistry of diamond bearing carbonate rocks from Kumdy Kol, Kochetav Massif, KazakhstaLithos, Vol. 70, 3-4, pp. 77-90.Russia, KazakhstanGeochemistry
DS200512-0499
2004
Ohta, M.Katayama, I., Ohta, M., Ogasawara, Y.Mineral inclusions in zircon from diamond bearing marble in the Kokchetav Massif, northern Kazakhstan.European Journal of Mineralogy, Vol. 14, 6, pp. 1103-1108.Russia, KazakhstanMineral inclusions
DS200912-0544
2009
Ohta, M.Odake, S., Fukura, S., Arakawa, S., Ohta, M., Harte, B., Kagi, H.Divalent chromium in ferropericlase inclusions in lower mantle diamonds revealed by morco XANES measurements.Journal of Mineralogical and Petrological Sciences, Vol. 103, 5, pp. 350-353.TechnologyDiamond inclusions
DS1996-0711
1996
Ohta, T.Kamioka, H., Shibata, K., Kajizuka, I., Ohta, T.Rare earth element patterns and carbon isotopic composition of carbonados -implications for originGeochem. Journal, Vol. 30, No. 3, pp. 189-194.GlobalCrustal origin -rare earth elements (REE)., Carbonados
DS200612-0824
2006
Ohtain, E.Litasov, K.D., Ohtain, E., Kagi, H., Lakshtanov, D.L., Bass, J.D.Hydrogen solubility in Al rich stidhovite and water transport to the lower mantle.Geochimica et Cosmochimica Acta, Vol. 70, 18, p. 23. abstract only.MantleWater
DS200612-1205
2006
Ohtain, E.Sakai, T., Kondo, T., Ohtain, E., Terasaki, H., Endo, N., Kuba, T., Suzuki, T., Kikegawa, T.Interaction between iron and post perovskite at core mantle boundary and core signature in plume source region.Geophysical Research Letters, Vol. 33, 15, August 16, L15317MantleGeophysics - seismics, boundary
DS200612-0601
2005
Ohtaini, E.Hosoya, T., Kubo, T., Ohtaini, E., Sano, A., Funakoshi, K.Water controls the fields of metastable olivine in cold subducting slabs.Geophysical Research Letters, Vol. 32, 17, Sept. 16, pp.Li7305-06.MantleSubduction
DS201412-0799
2014
Ohtaini, E.Shatskiy, A., Litasov, K., Palyanov, Y.N., Ohtaini, E.Phase relationships on the K2CO3 MgCOs join at 6 Gpa and 900-1400C: implications for incipient melting in carbonated mantle domains.V.S. Sobolev Institute of Geology and Mineralogy Siberian Branch Russian Academy of Sciences International Symposium Advances in high pressure research: breaking scales and horizons ( Courtesy of N. Poikilenko), Held Sept. 22-26, 2p. AbstractTechnologyDeposit - Ebelyakh, Udachnaya
DS202008-1460
2020
Ohtaini, E.Zedgenizov, D., Kagi, H., Ohtaini, E., Tsujimori, T., Komatsu, K.Retrograde phases of former bridgemanite inclusions in superdeep diamonds.Lithos, Vol. 370-371, 105659 7p. PdfAfrica, South Africa, Guinea, Australia,South America, Brazil, Canada, Northwest Territoriesdeposit - Koffiefontein, Kankan, Lac de Gras, Juina, Machado, Orroroo

Abstract: (Mg,Fe)SiO3 bridgmanite is the dominant phase in the lower mantle; however no naturally occurring samples had ever been found in terrestrial samples as it undergoes retrograde transformation to a pyroxene-type structure. To identify retrograde phases of former bridgmanite single-phase and composite inclusions of (Mg,Fe)SiO3 in a series of superdeep diamonds have been examined with electron microscopy, electron microprobe, Raman spectroscopy and X-ray diffraction techniques. Our study revealed that (Mg,Fe)SiO3 inclusions are represented by orthopyroxene. Orthopyroxenes in single-phase and composite inclusions inherit initial chemical composition of bridgmanites, including a high Al and low Ni contents. In composite inclusions they coexist with jeffbenite (ex-TAPP) and olivine. The bulk compositions of these composite inclusions are rich in Al, Ti, and Fe, which are similar but not fully resembling Al-rich bridgmanite produced in experiments on the MORB composition. The retrograde origin of composite inclusions due to decomposition of Al-rich bridgmanite may be doubtful because each of observed minerals may represent coexisting HP phases, i.e. bridgmanite or ringwoodite.
DS200412-1461
2004
Ohtaka, O.Ohtaka, O., Shimono, M., Ohnisi, N., Fukui, H., Takebe, H., Arima, H., Yamanaka, T.,Kikegawa, T., Kume, S.HIP production of a diamond/ SiC composite and application to high pressure anvils.Physics of the Earth and Planetary Interiors, Vol. 143-144, pp. 587-591.TechnologyUHP
DS201012-0213
2010
OhtaniFrost, D.F., Asahara, Y., Rubie, D.C., Miyajima, N., Dubrovinsky, Holzapfel, Ohtani, Miyahara, SakaiPartitioning of oxygen between the Earth's mantle and core.Journal of Geophysical Research, Vol. 115, B2 , B02202.MantleChemistry
DS1986-0617
1986
Ohtani, B.Ohtani, B., Herzberg, C.I.Stability of lherzolite magmas at solidus temperatures and 20 GPAEos, Vol. 67, No. 16, April 22, p. 408. AbstractGlobalLherzolites
DS1982-0287
1982
Ohtani, E.Irifune, T., Ohtani, E., Kumazawa, M.Stability Field of Knorringite Mg3 Chromium 2 Si3 012 at High Pressure and its implication to the Occurrence of Chromium Rich Pyrope in the Upper Mantle.Physics of The Earth And Plan. Interiors, Vol. 27, PP. 263-272.GlobalMineral Chemistry, Pyrope, Garnet
DS1982-0288
1982
Ohtani, E.Irifune, T., Ohtani, E., Kumazawa, M.Stability Field of Knorringite Mg3cr2si3o12 at High Pressure and its Implication to the Occurrence of Chromium Rich Pyrope In the Upper Mantle.Physics of The Earth And Planetary Interiors, Vol. 27, No. 4, PP. 263-272.RussiaGarnet, Kimberlite
DS1988-0300
1988
Ohtani, E.Herzberg, C., Feigenson, M., kuba, C., Ohtani, E.Majorite fractionation recorded in the geochemistry of peridotites from South AfricaNature, Vol. 332, No. 6167, April 28, pp. 823-826South AfricaBlank
DS1989-1147
1989
Ohtani, E.Ohtani, E., Kawabe, I., Moriyama, J., Nagata, Y.Partitioning of elements between majorite garnet and melt and Implications for petrogenesis of komatiiteContributions to Mineralogy and Petrology, Vol. 103, pp. 263-269. Database # 18231GlobalArchean mantle, Komatiite
DS1994-0062
1994
Ohtani, E.Arima, M., Yamashita, H., Ohtani, E.Melting experiments of kimberlite up to 8GPa and its bearing onMetasomatismGeological Association of Canada (GAC) Abstract Volume, Vol. 19, p.GlobalPetrology - experimenta, Metasomatism
DS1995-1378
1995
Ohtani, E.Ohtani, E., et al.Stability of hydrous phases in the transition zone and the upper most partof the lower mantle.Geophysical Research Letters, Vol. 22, No. 19, Oct. 1, pp. 2553-2556.MantleTransition zone
DS1995-1379
1995
Ohtani, E.Ohtani, E., Nagata, Y., Suzuki, A., Kato, T.Melting relations of peridotite and the density crossover in planetarymantles.Chemical Geology, Vol. 120, No. 3-4, March 1, pp. 207-221.MantleMelt, majorite, Magma
DS1995-1859
1995
Ohtani, E.Suzuki, A., Ohtani, E., Kato, T.Flotation of diamond in mantle melt at high pressureScience, Vol. 269, No. 5221, Jul 14, pp. 216-218.MantleDiamond genesis
DS1995-2096
1995
Ohtani, E.Yamashita, H., Arima, M., Ohtani, E.high pressure melting experiments on group II kimberlite up to 8 GPa:implications MetasomatismProceedings of the Sixth International Kimberlite Conference Abstracts, pp. 669-691.GlobalPetrology -experimental, Group II kimberlite
DS1996-0716
1996
Ohtani, E.Kato, T., Ohtani, E., Ito, Y., Onuma, K.Element partioning between silicate perovskites and calcic ultrabasicmelt.Physics of the Earth and Planetary Interiors, Vol. 86, 2-3, pp. 201-207.MantlePerovskites, Kimberlite petrogenesis
DS1997-0224
1997
Ohtani, E.Courtal, P., Ohtani, E., Dingwell, D.B.High temperature densities of some mantle meltsGeochimica et Cosmochimica Acta, Vol. 61, No. 15, pp. 3111-19.MantleMelting
DS1997-0867
1997
Ohtani, E.Ohtani, E., Yurimoto, H., Seto, S.Element partitioning between metallic liquid, silicate liquid and Lower Mantle mineral: implications for corePhysics of the Earth and Plan. Interiros, Vol. 100, pp. 97-114.MantleGeothermometry, Heat transport, silicates
DS1998-1091
1998
Ohtani, E.Ohtani, E., Suzuki, A., Kato, T.Flotation of olivine and diamond in mantle melt at high pressure:implications for fractionation in deep mantleAmerican Geophysical Union (AGU) Geo. Mon., No. 101, pp.MantleMelt, Olivine - diamond
DS1998-1429
1998
Ohtani, E.Suzuki, A., Ohtani, E., Kato-TakumiDensity and thermal expansion of a peridotite melt at high pressurePhysical Earth and Planetary Interiors, Vol. 107, No. 1-3, pp. 53-61.MantleMelting, ultra high pressure (UHP)
DS1998-1609
1998
Ohtani, E.Yamashita, H., Arima, M., Ohtani, E.Melting experiments of kimberlite compositions up to 9 GPa: determination of melt compositions using aggregate7th International Kimberlite Conference Abstract, pp. 977-9.GlobalExperimental petrology, Mineral chemistry
DS2001-0052
2001
Ohtani, E.Asahara, Y., Ohtani, E.Melting relations of the hydrous primitive mantle in the CMAS H2O system at high pressures and temperaturesPhysics of the Earth and Planetary Interiors, Vol. 125, No. 1-4, pp. 31-44.MantleKomatiites - not specific to diamonds
DS2001-0053
2001
Ohtani, E.Asahera, Y., Ohtani, E.Melting relations of the hydrous primitive mantle in the CMAS - H2O systemat high pressures and temperaturePhysical Earth and Planetary Interiors, Vol. 125, No. 1-4, pp. 31-44.MantleMelting
DS2001-0691
2001
Ohtani, E.Litasov, K.D., Ohtani, E., Dobretsov, N.L.Stability of hydrous phase in the Earth's mantleDoklady Academy of Sciences, Vol. 378, No. 4, pp. 456-9.MantleGeochemistry
DS2001-0848
2001
Ohtani, E.Ohtani, E., Litasov, K., Suzuki, A., Kondo, T.Stability field of new hydrous mantle phase with implications for water transport into the deep mantle.Geophysical Research Letters, Vol. 28, No. 20, Oct. 15, pp. 3991-4.MantleMineral chemistry
DS2001-0849
2001
Ohtani, E.Ohtani, E., Maeda, M.Density of basaltic melt at high pressure and stability of the melt at the base of the lower mantle.Earth and Planetary Science Letters, Vol. 193, No. 1-2, pp. 69-75.MantleMorb, picrites, floating diamond method, peridotites, D Layer, discontinuity
DS2001-0850
2001
Ohtani, E.Ohtani, E., Toma, Litasov, Kubo, SuzukiStability of dense hydrous magnesium silicate phases and water storage capacity in transition zone -Physical Earth and Planetary Interiors, Vol. 124, No. 1-2, pp. 105-117.MantleSlab melting, water
DS2001-1142
2001
Ohtani, E.Suzuki, A., Ohtani, E., Kondo, T., et al.Neutron diffraction study of hydrous phase G: hydrogen in the lower mantle hydrous silicate phase G.Geophysical Research Letters, Vol. 28, No. 20, Oct. 15, pp. 3987-90.MantleMineral chemistry
DS2002-0798
2002
Ohtani, E.Kabo, T., Ohtani, E., Kondo, T., Kato, T., Toma, M., Hosoya, T., Sano, A.Metastable garnet in oceanic crust at the top of the lower mantleNature, No. 6917, Dec. 19, pp. 803-5.MantleGarnet mineralogy
DS2002-1178
2002
Ohtani, E.Ohtani, E., Litasov, K.D.Phase and melting relations of peridotite H2O and basalt H2O systems to the top of the lower mantle and implications for slab subduction and hot mantle plume.18th. International Mineralogical Association Sept. 1-6, Edinburgh, abstract p.75.MantleUHP - mineralogy
DS2003-0823
2003
Ohtani, E.Litasov, K., Ohtani, E., Langenhorst, F., Yurimoto, H., Kubo, T., Kondo, T.Water solubility in Mg perovskites and water storage capacity in the lower mantleEarth and Planetary Science Letters, Vol. 211, 1-2, June 15, pp. 189-203.MantleWater storage
DS2003-0824
2003
Ohtani, E.Litasov, K., Ohtani, E., Langenhorst, F., Yurimoto, H., Kubo, T., Kondo, T.Water solubility in Mg perovskites and water storage capacity in the lower mantleEarth and Planetary Science Letters, Vol. 211, 1-2, pp. 189-203.MantleBlank
DS2003-0826
2003
Ohtani, E.Litasov, K.D., Ohtani, E.Hydrous lower mantle: the water source for wet plumes8 Ikc Www.venuewest.com/8ikc/program.htm, Session 6, POSTER abstractMantleBlank
DS2003-1350
2003
Ohtani, E.Suzuki, A., Ohtani, E.Density of peridotite melts at high pressurePhysics and Chemistry of Minerals, Vol. 30, 8, Sept. pp. 449-56.MantleMineral chemistry
DS200412-1143
2003
Ohtani, E.Litasov, K., Ohtani, E.Hydrous solidus of CMAS pyrolite and melting of mantle plumes at the bottom of the upper mantle.Geophysical Research Letters, Vol. 22, SDE 2 Nov. 15, 10.1029/2003 GLO18318MantleGeochemistry - plumes
DS200412-1144
2003
Ohtani, E.Litasov, K., Ohtani, E., Langenhorst, F., Yurimoto, H., Kubo, T., Kondo, T.Water solubility in Mg perovskites and water storage capacity in the lower mantle.Earth and Planetary Science Letters, Vol. 211, 1-2, June 15, pp. 189-203.MantleWater storage
DS200412-1147
2003
Ohtani, E.Litasov, K.D., Ohtani, E.Hydrous lower mantle: the water source for wet plumes.8 IKC Program, Session 6, POSTER abstractMantleMantle petrology
DS200412-1953
2003
Ohtani, E.Suzuki, A., Ohtani, E.Density of peridotite melts at high pressure.Physics and Chemistry of Minerals, Vol. 30, 8, Sept. pp. 449-56.MantleMineral chemistry
DS200512-0645
2005
Ohtani, E.Litasov, K., Ohtani, E., Sano, A., Suzuki, A., Funakoshi, K.In situ X-ray diffraction study of post spinel transformation in a peridotite mantle: implication for the 660 km discontinuity.Earth and Planetary Science Letters, Vol.238, 3-4, pp. 311-328.MantleUHP, ringwoodite, perovskite
DS200512-0646
2005
Ohtani, E.Litasov, K.D., Ohtani, E.Phase relations in hydrous MORB at 18 - 28 GPa: implications for heterogeneity of the lower mantle.Physics of the Earth and Planetary Interiors, Vol. 150, 4, June 15, pp. 239-263.MantleSubduction, slab, UHP
DS200512-0803
2004
Ohtani, E.Ohtani, E.Water in the mantle.Elements, Vol. 1, 1, Jan. pp. 25-30.MantleSubduction, slab, transition zone, DHMS phase
DS200612-0456
2006
Ohtani, E.Ghosh, S., Ohtani, E., Litasov, K.D., Suzuki, A.Density of carbonated basaltic melt at the conditions of Earth's upper mantle.Geochimica et Cosmochimica Acta, Vol. 70, 18, p. 15, abstract only.MantleMelting
DS200612-0457
2006
Ohtani, E.Ghosh, S., Ohtani, E., Litasov, K.D., Suzuki, A., Terasaki, H.Solidus of carbonated peridotite tp 20 GPa.International Mineralogical Association 19th. General Meeting, held Kobe, Japan July 23-28 2006, Abstract p. 140.MantleMelting
DS200612-0519
2006
Ohtani, E.Hae, R., Ohtani, E., Kubo, T., Koyama, T., Utada, H.Hydrogen diffusivity in wadsleyite and water distribution in the mantle transition zone.Earth and Planetary Science Letters, Vol. 243,1-2, Mar. 15, pp. 141-148.MantleIR spectroscopy
DS200612-0585
2006
Ohtani, E.Hirao, N., Kondo, T., Ohtani, E., Kikegawa, T.Post hollandite phase in KAlSi308 as a possible host mineral of potassium in the Earth's lower mantle.International Mineralogical Association 19th. General Meeting, held Kobe, Japan July 23-28 2006, Abstract p. 130.MantleMineralogy
DS200612-0825
2006
Ohtani, E.Litasov, K.D., Ohtani, E., Kagi, H., Ghosh, S.Water partitioning between olivine and wadsleyite near 410 km seismic discontinuity.International Mineralogical Association 19th. General Meeting, held Kobe, Japan July 23-28 2006, Abstract p.102.MantleDiscontinuity - width
DS200612-1002
2006
Ohtani, E.Ohtani, E.Perovskite and post perovskite stability, geochemical and geodynamical consequences.Goldschmidt Conference 16th. Annual, S4-05 theme abstract 1/8p. goldschmidt2006.orgMantleGeochemistry
DS200612-1003
2006
Ohtani, E.Ohtani, E.Effect of water on dynamics in the upper mantle and transition zone.International Mineralogical Association 19th. General Meeting, held Kobe, Japan July 23-28 2006, Abstract p. 132.MantleGeodynamics
DS200612-1004
2005
Ohtani, E.Ohtani, E.Recent progress in experimental mineral physics: phase relations of hydrous systems and the role of water in slab dynamics.American Geophysical Union, Geophysical Monograph, ed. Van der Hilst, Earth's Deep mantle, structure ...., No. 160, pp. 321-MantleSubduction
DS200612-1005
2006
Ohtani, E.Ohtani, E., Litasov, K.D.The effect of water on mantle phase transitions.Reviews in Mineralogy and Geochemistry, Vol. 62, pp. 397-420.MantleWater - chemistry
DS200612-1183
2006
Ohtani, E.Rubie, D.C., Duffy, T.S., Ohtani, E.New developments in high pressure mineral physics and applications to the Earth's interior.Elsevier, 750p. approx. $ 120 USMantleBook - mantle mineralogy, volatiles, rheology, melting
DS200612-1206
2006
Ohtani, E.Sakai, T., Kondo, T., Ohtani, E., Terasaki, H., Miyahara, Yoo, Endo, Kuba, Suzuki, KikegawaWetting property at the core mantle boundary and core signature in plume source region.International Mineralogical Association 19th. General Meeting, held Kobe, Japan July 23-28 2006, Abstract p. 129.MantleGeophysics - seismics
DS200612-1207
2006
Ohtani, E.Sakamaki, T., Suzuki, A., Ohtani, E.Stability of hydrous melt at the base of the Earth's upper mantle.Nature, No. 7073, Jan. 12, pp. 192-194.MantleMelting
DS200612-1221
2006
Ohtani, E.Sano, A., Ohtani, E., Litasov, K., Kubo, T., Hosoya, T., Funakoshi, K., Kikegawa, T.In situ x-ray diffraction study of the effect of water on the garnet perovksite transformation in MORB and implications for the penetration of oceanic crust...Physics of the Earth and Planetary Interiors, Vol. 159, 1-2, pp. 118-126.MantleWater in lower mantle
DS200712-0631
2007
Ohtani, E.Litasov, K.D., Ohtani, E.Effect of water on the phase relations in Earth's mantle and deep water cycle.Ohtani: Advances in high pressure mineralogy, pp. 115-156.MantleWater
DS200712-0632
2006
Ohtani, E.Litasov, K.D., Ohtani, E., Sano, A.Influence of water on major phase transitions in the Earth's mantle.American Geophysical Union, Geophysical Monograph, No. 168, pp. 95-112.MantleWater
DS200712-0786
2007
Ohtani, E.Ohtani, E.Advances in high-pressure mineralogy.GSA Bookstore, No. 421, approx. 300p. Cost Member 67.00 non- 95.00TechnologyIndividual chapters of interest cited separately
DS200712-0933
2007
Ohtani, E.Sanchez-Valle, C., Litasov, K., Ohtani, E., Bass, E.Sound velocities and single crystal properties of DHMS phase E to high pressure.Frontiers in Mineral Sciences 2007, Joint Meeting of Mineralogical societies Held June 26-28, Cambridge, Abstract Volume p.193.MantleTransition zone
DS200712-0934
2007
Ohtani, E.Sanchez-Valle, C., Litasov, K., Ohtani, E., Bass, E.Sound velocities and single crystal properties of DHMS phase E to high pressure.Frontiers in Mineral Sciences 2007, Joint Meeting of Mineralogical societies Held June 26-28, Cambridge, Abstract Volume p.193.MantleTransition zone
DS200712-0948
2007
Ohtani, E.Schich, S.R., Duffy, T.S., Liu, Z., Ohtani, E.The hydrogen within the deep mantle.Frontiers in Mineral Sciences 2007, Joint Meeting of Mineralogical societies Held June 26-28, Cambridge, Abstract Volume p.153.MantleHydrogen budget
DS200712-0949
2007
Ohtani, E.Schich, S.R., Duffy, T.S., Liu, Z., Ohtani, E.The hydrogen within the deep mantle.Frontiers in Mineral Sciences 2007, Joint Meeting of Mineralogical societies Held June 26-28, Cambridge, Abstract Volume p.153.MantleHydrogen budget
DS200812-0406
2007
Ohtani, E.Ghosh, S., Ohtani, E., Litasov, K., Suzuki, A., Sakamaki, T.Stability of carbonated magmas at the base of the Earth's upper mantle.Geophysical Research Letters, Vol. 34, 22, pp. L22312.MantlePetrology
DS200812-0471
2008
Ohtani, E.Hirao, N., Ohtani, E., Kondo, T., Sakari, T., Kikegawa, T.Hollandite II phase in KAiSi3O8 as a potential host mineral of potassium in the Earth's lower mantle.Physics of the Earth and Planetary Interiors., Vol. 166, 1-2, pp. 97-104.MantlePotassium
DS200812-0818
2008
Ohtani, E.Ohtani, E.Chemical reactions and element partitioning at the core mantle boundary.Goldschmidt Conference 2008, Abstract p.A702.MantleBoundary
DS200812-1058
2007
Ohtani, E.Shiraishi, R., Ohtani, E.Raman spectroscopic study of a garnetite xenolith from Malaita, southwest Pacific.Journal of Mineralogical and Petrological Sciences, Vol. 102, 6, pp. 337-345.Asia, Solomon IslandsXenoliths
DS200912-0250
2009
Ohtani, E.Ghosh, S., Ohtani, E., Litasov, K.Partial melting of peridotite + CO2 and origin of kimberlite melt in the deep mantle.Goldschmidt Conference 2009, p. A433 Abstract.MantleMelting
DS200912-0251
2009
Ohtani, E.Ghosh, S., Ohtani, E., Litsov, K.D., Terasaki, H.Solidus of carbonated peridotite from 10 to 20 GPa and origin of magnesiocarbonatite melt in the Earth's deep mantle.Chemical Geology, Vol. 262, 1-2, May 15, pp. 17-28.MantleCarbonatite
DS200912-0440
2009
Ohtani, E.Litasov, K.D., Ohtani, E.Phase relations in the peridotite carbonate chloride system at 7.0- and 16.5 GPa and the rock of chlorides in the origin of kimberlite and diamond.Chemical Geology, Vol. 262, 1-2, May 15, pp. 29-41.MantleDiamond genesis
DS200912-0441
2009
Ohtani, E.Litasov, K.D., Ohtani, E.Eclogite carbonate chloride system at 7.0-16.5 GPa: implications to diamond and mantle fluids.Goldschmidt Conference 2009, p. A773 Abstract.MantleDiamond inclusions
DS200912-0548
2009
Ohtani, E.Ohtani, E.Melting relations and the equation of state of magmas at high pressure: application to geodynamics.Chemical Geology, Vol. 265, 3-4, pp. 279-288.MantleMelting
DS200912-0857
2009
Ohtani, E.Zhao, D., Ohtani, E.Deep slab subduction and dehydration and their geodynamic consequences: evidence from seismology and mineral physics.Gondwana Research, Vol. 16, 3-4, pp. 401-413.MantleSubduction
DS201012-0014
2009
Ohtani, E.Asanuma, H., Ohtani, E., Sakai, T., Terasaki, H., Kamada, S., Kondo, T., Kikegawa, T.Melting of iron silicon alloy up to the core mantle boundary pressure: implications to the thermal structure of the Earth's core.Physics and Chemistry of Minerals, Vol. 37, 6, pp. 353-359.MantleMelting
DS201012-0060
2010
Ohtani, E.Bobrov, A., Dymshits, A., Litvin, Yu., Litasov, K., Shatskiy, A., Ohtani, E.Sodium bearing majorite garnet: nature and experimental aspects.International Mineralogical Association meeting August Budapest, abstract p. 148.Russia, Timan, South America, Brazil, ChinaUHP
DS201012-0113
2010
Ohtani, E.Collerson, K.D., Williams, Q., Kamber, B.S., Omori, S., Arai, H., Ohtani, E.Majoritic garnet: a new approach to pressure estimation of shock events in meteorites and the encapsulation of sub-lithospheric inclusions in diamonds.Geochimica et Cosmochimica Acta, Vol. 74, 20, pp. 5939-5937.TechnologyMeteorite
DS201012-0447
2010
Ohtani, E.Litasov, K., Ohtani, E.The solidus of carbonated eclogite in the system CaO Al2O3 MgO SiO2 Na2O CO2 to 32 GPa and carbonatite liquid in the deep mantle.Earth and Planetary Science Letters, Vol. 295, 1-2, pp. 115-126.MantleCarbonatite
DS201012-0448
2010
Ohtani, E.Litasov, K.D., Safonov, O.G., Ohtani, E.Origin of Cl bearing silica rich melt inclusions in diamonds: experimental evidence for an eclogite connection.Geology, Vol. 38, 12, Dec. pp. 1131-1134.TechnologyMelting phase relations, chlorine
DS201012-0549
2009
Ohtani, E.Ohtani, E., Zhao, D.The role of water in the deep upper mantle and transition zone: dehydration of stagnant slabs and the effects on the big mantle wedge.Russian Geology and Geophysics, Vol. 50, 12, pp. 1073-1078.MantleWater
DS201012-0651
2009
Ohtani, E.Sakamaki, T., Ohtani, E., Urakawa, S., Suzuki, A., Katayama, Y.Density of dry peridotite magma at high pressure using an x-ray absorption method.American Mineralogist, Vol. 95, pp. 144-147.TechnologyUHP
DS201112-0606
2010
Ohtani, E.Litasov, K.D., Sharygin, I.S., Shatskiy, A.F., Ohtani, E., Pokhilenko, N.P.Experimental constraints on the role of chloride in the origin and evolution of kimberlitic magma.Doklady Earth Sciences, Vol. 435, 2, pp. 1641-1646.MantleMineralogy
DS201112-0607
2011
Ohtani, E.Litasov, K.D., Shatskiy, A., Ohtani, E.Melting in the peridotite and eclogite coexisting with reduced C-O-H fluid at 3.16 GPa.Goldschmidt Conference 2011, abstract p.1335.MantleRedox melting - graphite and diamond crystals
DS201112-0901
2011
Ohtani, E.Sakamaki, T., Ohtani, E., Urakawa, S., Terasaki, H., Katayama, Y.Density of carbonated peridotite magma at high pressure using an X-ray absorption method.American Mineralogist, Vol. 96, pp. 553-557.MantleHP
DS201212-0178
2012
Ohtani, E.Dymshits, A.M., Bindi, L., Bobrov, A.V., Litasov, K.D., Shatskiy, A.F., Ohtani, E., Litvin, Yu.A.Sodium majorite and its pyrope solid solutions high pressure experiment and crystal chemical implications.10th. International Kimberlite Conference Feb. 6-11, Bangalore India, AbstractTechnologyMineral Chemistry
DS201212-0356
2012
Ohtani, E.Kiseeva, E.S., Litasov, K.D., Yaxley, G.M., Ohtani, E.Carbonated eclogite at 3.5-5.5 Gpa - the effect of the capsule material on solidus temperatures.10th. International Kimberlite Conference Held Bangalore India Feb. 6-11, Poster abstractTechnologyDiamond/carbon crystallography
DS201212-0357
2012
Ohtani, E.Kiseeva, E.S., Litasov, K.D., Yaxley, G.M., Ohtani, E., Kamenetsky, V.S.Phase relations of eclogite + 4% CO2 at 9-21 GPA: implications for diamond formation in the deep mantle.10th. International Kimberlite Conference Feb. 6-11, Bangalore India, AbstractMantleDiamond genesis
DS201212-0411
2012
Ohtani, E.Litasov, K.D., Shatskiy, A., Ohtani, E.Melting of peridotite and eclogite coexisting with reduced C-O-H fluid at 3-16 Gpa: further constraints for redox melting models.10th. International Kimberlite Conference Held Bangalore India Feb. 6-11, Poster abstractMantleRedox
DS201212-0412
2012
Ohtani, E.Litasov, K.D., Shatskiy, A., Ohtani, E., Pokhilenko, N.P.Melting phase relations in the systems peridotite-H2O-CO2 and eclogite-H2O-CO2 at pressures up to 27 Gpa.10th. International Kimberlite Conference Held Bangalore India Feb. 6-11, Poster abstractMantleMelting
DS201212-0413
2012
Ohtani, E.Litasov, K.D., Shatsky, A., Ohtani, E.Melting of peridotite and eclogite coexisting with reduced C-O-H fluid at 3-16 GPA: further constraints on redox melting models.10th. International Kimberlite Conference Feb. 6-11, Bangalore India, AbstractMantleMelting
DS201212-0638
2012
Ohtani, E.Sharygin, I.S., Litasov, K.D., Shatskiy, A., Golovin, A.V., Ohtani, E., Pokhilenko, N.P.Melting phase relations of chlorine bearing kimberlite at 2.1-6.5 GPA and 900-1500 ON10th. International Kimberlite Conference Feb. 6-11, Bangalore India, AbstractMantleMelting
DS201212-0640
2012
Ohtani, E.Shatskiy, A., Litasov, K.D., Ohtani, E.Segregation rate and transport mechanism of volatile bearing melt in the deep mantle.10th. International Kimberlite Conference Held Bangalore India Feb. 6-11, Poster abstractMantleMelting
DS201312-0486
2013
Ohtani, E.Kiseeva, E.S., Litasov, K.D., Yaxley, G.M., Ohtani, E., Kamenetsky, V.S.Melting and phase relations of carbonated eclogite at 9-21 GPa and the petrogenesis of alkali rich melts in the deep mantle.Journal of Petrology, Vol. 54, 8, pp. 1555-1583.MantleEclogite
DS201312-0543
2013
Ohtani, E.Litasov, K.D., Shatskiy, A., Ohtani, E., Yaxley, G.M.Solidus of alkaline carbonatite in the deep mantle.Geology, Vol. 41, pp. 79-82.MantleCarbonatite
DS201312-0544
2013
Ohtani, E.Litasov, K.D., Shatsky, A., Ohtani, E.Deep melting of subducted carbonate and carbonatite melt diapirs in the Earth's mantle.Goldschmidt 2013, AbstractMantleMelting
DS201312-0803
2013
Ohtani, E.Sharygin, I.S., Litasov, K.D., Shatskiy, A., Golovin, A.V., Ohtani, E., Pokhilenko, N.P.Melting phase relations in Udachnaya-East kimberlite and search for parental melt composition. Group IGoldschmidt 2013, AbstractRussiaDeposit - Udachnaya
DS201412-0216
2014
Ohtani, E.Dymshits, A., Litasov, K., Sharygin, I., Shatskiy, A., Ohtani, E.Mineral physics of high pressure garnets.V.S. Sobolev Institute of Geology and Mineralogy Siberian Branch Russian Academy of Sciences International Symposium Advances in high pressure research: breaking scales and horizons ( Courtesy of N. Poikilenko), Held Sept. 22-26, 2p. AbstractTechnologyGarnet
DS201412-0285
2014
Ohtani, E.Ghosh, S., Litasov, K., Ohtani, E.Phase relations and melting of carbonated peridotite between 10 and 20 Gpa: a proxy for alkali and CO2 rich silicate melts in the deep mantle.Contributions to Mineralogy and Petrology, Vol. 167, pp. 964-972.MantleMelting
DS201412-0514
2014
Ohtani, E.Litasov, K.D., Shatskiy, A., Ohtani, E.Melting and subsolidus phase relations in peridotite and eclogite systems with reduced C O H fluid at 3-16 Gpa.Earth and Planetary Science Letters, Vol. 391, 1, pp. 87-99.MantleMelting
DS201412-0542
2014
Ohtani, E.Maeda, F., Ohtani, E., Kamada, S., Sakamaki, T., Ohishi, Y., Hirao, N.The reactions in the MgCO3-SiO2 system in the slabs subducted into the lower mantle and formation of deep diamond.V.S. Sobolev Institute of Geology and Mineralogy Siberian Branch Russian Academy of Sciences International Symposium Advances in high pressure research: breaking scales and horizons ( Courtesy of N. Poikilenko), Held Sept. 22-26, 1p. AbstractSouth America, BrazilCarbon
DS201412-0609
2014
Ohtani, E.Mysen, B., Tomita, T., Ohtani, E., Suzuki, A.Speciation of and D/H partioning between fluids and melts in silicate D-O-H-C-N systems determined in-situ at upper mantle temperatures, pressures, and redox conditions.American Mineralogist, Vol. 99, pp. 578-588.MantleMelting
DS201412-0645
2014
Ohtani, E.Ohira, I., Ohtani, E., Sakai, T., Miyahara, M., Hirao, N., Ohishi, Y., Nishijima, M.Stability of a hydrous delta phase AlOOH-MgSiO2(OH)2, and a mechanism for water transport into the base of lower mantle.Earth and Planetary Science Letters, Vol. 401, pp. 12-17.MantleWater
DS201412-0771
2013
Ohtani, E.Sakamaki, T., Suzuki, A., Ohtani, E., Terasaki, H., Urakawa, S.Ponded melt at the boundary between the lithosphere and asthenosphere.Nature Geoscience, Vol. 6, no. 12, pp. 1041-1044.MantleMagmatism - ponding
DS201412-0795
2014
Ohtani, E.Sharygin, I., Litasov, K., Shatskiy, A., Golovin, A., Ohtani, E., Pokhilenko, N.Is kimberlite magma ascent fuelled by CO2 degassing via orthopyroxene assimilation?V.S. Sobolev Institute of Geology and Mineralogy Siberian Branch Russian Academy of Sciences International Symposium Advances in high pressure research: breaking scales and horizons ( Courtesy of N. Poikilenko), Held Sept. 22-26, 2p. AbstractTechnologyModel
DS201412-0796
2014
Ohtani, E.Sharygin, I., Litasov, K., Shatskiy, A., Golovin, A., Ohtani, E., Pokhilenko, N.Melting phase relations of the Udachnaya East Group 1 kimberlite at 3.0-6.5 GPA: experimental evidence for alkali-carbonatite composition of primary kimberlite melt.V.S. Sobolev Institute of Geology and Mineralogy Siberian Branch Russian Academy of Sciences International Symposium Advances in high pressure research: breaking scales and horizons ( Courtesy of N. Poikilenko), Held Sept. 22-26, 2p. AbstractRussia, YakutiaDeposit - Udachnaya-East
DS201412-0798
2014
Ohtani, E.Sharygin, I.S., Litasov, K.D., Shatskiy, A., Golovin, A.V., Ohtani, E., Pokhilenko, N.P.Melting phase relations of the Udachnaya-East Group 1 kimberlite at 3.0-6.5GPa: experimental evidence for alkali-carbonatite composition of primary kimberlite melts and implications for mantle plumes.Gondwana Research, in press availableRussiaDeposit - Udachnaya-East
DS201412-0800
2014
Ohtani, E.Shatskiy, A.F., Sharygin, I.S., Litasov, K.D., Ohtani, E.Effect of CO2 content on melting phase relations in kimberlite Group 1 at 6.5 Gpa and 1200-1600C : implcations for the parental magma composition.30th. International Conference on Ore Potential of alkaline, kimberlite and carbonatite magmatism. Sept. 29-, http://alkaline2014.comMantleKimberlite
DS201502-0103
2015
Ohtani, E.Sobolev, N.V., Dobretsov, N.I., Ohtani, E., Taylor, L.A., Schertl, H-P., Palyanov, Yu.N.Problems related to crystallogenesis and the deep carbon cycle.Russian Geology and Geophysics, Vol. 56, 1-2, pp. 1-12.MantleCarbon cycle
DS201503-0164
2015
Ohtani, E.Ohtani, E., Amaike, Y., Kamada, S., Sakamaki, T., Hirao, N.Stability of hydrous phase H MgSi04H2 under lower mantle conditions.Geophysical Research Letters, Vol. 41, 23, pp. 8283-8287.MantleMineralogy
DS201504-0194
2015
Ohtani, E.Dymshits, A., Sharygin, I., Litasov, K., Shatskiy, A., Gavryushkin, P., Ohtani, E., Suzuki, A., Funakoshi, K.In situ observation of the pyroxene majorite transition in Na2MgSi5O12 using synchroton radiation and Raman spectroscopy of Na-majorite.American Mineralogist, Vol. 100, pp. 378-384.MantleMajorite
DS201506-0284
2015
Ohtani, E.Miyahara, M., Ohtani, E., El Goresy, A., Lin, Y., Feng, L.,Zhang, J-C., Gillet, P., Nagase, T., Muto, J., Nishijima, M.Unique large diamonds in a urelilite from Almahat a Sitta TC3, asteroid.Geochimica et Cosmochimica Acta, Vol. 163, pp. 14-26.TechnologyUrelilite
DS201510-1795
2015
Ohtani, E.Ohtani, E.Hydrous minerals and the storage of water in the deep mantle.Chemical Geology, Vol. 418, pp. 6-15.MantleWater

Abstract: Water is transported into the deep mantle via hydrous minerals in subducting slabs. During subduction, a series of minerals in these slabs such as serpentine or chlorite, Mg-sursassite and/or the 10 Å phase, and phase A can be stable at different pressures within the slab geotherms, and may transport significant amount of water into the Earth's interior. The transition zone has a large water storage capacity because of the high solubility of water in wadsleyite and ringwoodite. The recent discovery of hydrous ringwoodite and phase Egg as inclusions in ultra deep diamonds from Juina, Brazil suggests that the transition zone may indeed contain water. Seismic tomographic studies and electrical conductivity observations suggest that the transition zone may contain large amount of water, at least locally, beneath the subduction zones. The discovery of a new hydrous phase H, MgSiO2(OH)2, and its solid solution with isostructural phase d-AlOOH, suggests that a significant amount of water could be stored in this hydrous magnesium silicate phase which is stable down to the lower mantle. Water may be transported into the bottom of the lower mantle via phase H–d solid solution in descending slabs. This new high pressure hydrous phase solid solution has a high bulk modulus and sound velocity owing to strong O-H bonding due to hydrogen bond symmetrization in the lower mantle. Therefore, water stored in this hydrous phase would not reduce the seismic wave velocity in the lower mantle, and is seismically invisible. Dehydration melting could then occur at the base of the lower mantle, providing a potential explanation for the ultralow-velocity zone at the core-mantle boundary. When this hydrous magnesium silicate phase or hydrous melt makes contact with the metallic outer core at the core-mantle boundary, then hydrogen is likely to dissolve into the core.
DS201604-0625
2015
Ohtani, E.Sharygin, I.S., Litasov, K.D., Shatskiy, A., Golovin, A.V., Ohtani, E., Pokhilenko, N.P.Melting phase relations of the Udachnaya-East group 1 kimberlite at 3.0-6.5 Gpa: experimental evidence for alkali- carbonatite composition of primary kimberlite melts and implications for mantle plumes.Gondwana Research, Vol. 28, pp. 1391-1414.RussiaDeposit - Udachnaya -East

Abstract: Experiments on the origin of the Udachnaya-East kimberlite (UEK) have been performed using a Kawai-type multianvil apparatus at 3-6.5GPa and 900-1500°C. The studied composition represents exceptionally fresh Group-I kimberlite containing (wt.%): SiO2=25.9, TiO2=1.8, Al2O3=2.8, FeO=9.0, MgO=30.1, CaO=12.7, Na2O=3.4, K2O=1.3, P2O5=1.0, Cl=0.9, CO2=9.9, and H2O=0.5. The super-solidus assemblage consists of melt, olivine (Ol), Ca-rich (26.0-30.2wt.% CaO) garnet (Gt), Al-spinel (Sp), perovskite (Pv), a CaCO3 phase (calcite or aragonite), and apatite. The low pressure assemblage (3-4GPa) also includes clinopyroxene. The apparent solidus was established between 900 and 1000°C at 6.5GPa. At 6.5GPa and 900°C Na-Ca carbonate with molar ratio of (Na+K)/Ca˜0.44 was observed. The UEK did not achieve complete melting even at 1500°C and 6.5GPa, due to excess xenogenic Ol in the starting material. In the studied P-T range, the melt has a Ca-carbonatite composition (Ca#=molar Ca/(Ca+Mg) ratio=0.62-0.84) with high alkali and Cl contents (7.3-11.4wt.% Na2O, 2.8-6.7wt.% K2O, 1.6-3.4wt.% Cl). The K, Na and Cl contents and Ca# decrease with temperature. It is argued that the primary kimberlite melt at depths>200km was an essentially carbonatitic (<5wt.% SiO2), but evolved toward a carbonate-silicate composition (up to 15-20wt.% SiO2) during ascent. The absence of orthopyroxene among the run products indicates that xenogenic orthopyroxene was preferentially dissolved into the kimberlite melt. The obtained subliquidus phase assemblage (Ol+Sp+Pv+Ca-rich Gt) at P-T conditions of the UEK source region, i.e. where melt was in the last equilibrium with source rock before magma ascent, differs from the Opx-bearing peridotitic mineral assemblage of the UEK source region. This difference can be ascribed to the loss of substantial amounts of CO2 from the kimberlite magma at shallow depths, as indicated by both petrological and experimental data. Our study implies that alkali-carbonatite melt would be a liquid phase within mantle plumes generated at the core-mantle boundary or shallower levels of the mantle, enhancing the ascent velocity of the plumes. We conclude that the long-term activity of a rising hot mantle plume and associated carbonatite melt (i.e. kimberlite melt) causes thermo-mechanical erosion of the subcontinental lithosphere mantle (SCLM) roots and creates hot and deformed metasomatic regions in the lower parts of the SCLM, which corresponds to depths constrained by P-T estimates of sheared Gt-peridotite xenoliths. The sheared Gt-peridotites undoubtedly represent samples of these regions.
DS201605-0867
2016
Ohtani, E.Mashino, I., Murakami, M., Ohtani, E.Sound vehicles of AlOOH up to core mantle boundary pressures with implications for the seismic anomalies in the deep mantle.Journal of Geophysical Research,, Vol. 121, 2, pp. 595-609.MantleBoundary
DS201611-2139
2016
Ohtani, E.Sharygin, I.S., Litasov, K.D., Shatskiy, A., Safonov, O.G., Golovin, A.V., Ohtani, E., Pokhilenko, N.P.Experimental constraints on orthopyroxene dissolution in alkali carbonate melts in the lithospheric mantle: implications for kimberlite melt composition and magma ascent.Chemical Geology, in press available 42p.TechnologyMagma melting

Abstract: Although kimberlite magma carries large amounts of mantle-derived xenocrysts and xenoliths (with sizes up to meters), this magma ascends from the Earth's mantle (> 150-250 km) to the surface in a matter of hours or days, which enables diamonds to survive. The recently proposed assimilation-fuelled buoyancy model for kimberlite magma ascent emphasizes the importance of fluid CO2 that is produced via the reactive dissolution of mantle-derived orthopyroxene xenocrysts into kimberlite melt, which initially has carbonatitic composition. Here, we use a series of high-pressure experiments to test this model by studying the interaction of orthopyroxene (Opx) with an alkali-dolomitic melt (simplified to 0.7Na2CO3 + 0.3K2CO3 + 2CaMg(CO3)2), which is close to the melt that is produced by the partial melting of a kimberlite source, at P = 3.1-6.5 GPa and T = 1200-1600 °C, i.e., up to pressures that correspond to depths (~ 200 km) from where the ascent of kimberlite magma would start. During the first set of experiments, we study the reaction between powdered Opx and model carbonate melt in a homogeneous mixture. During the second set of experiments, we investigate the mechanism and kinetics of the dissolution of Opx crystals in alkali-dolomitic melt. Depending on the P-T conditions, Opx dissolves in the alkali-dolomitic melt (CL) either congruently or incongruently via the following reactions: Mg2Si2O6 (Opx) + CaMg(CO3)2 (CL) = CaMgSi2O6 (clinopyroxene) + 2MgCO3 (CL) and Mg2Si2O6 (Opx) = Mg2SiO4 (olivine) + SiO2 (CL). The experiments confirm that the dissolution of Opx causes gradual SiO2 enrichment in the initial carbonate melt, as previously suggested. However, the assimilation of Opx by carbonate melt does not produce fluid CO2 in the experiments because the CO2 is totally dissolved in the evolved melt. Thus, our results clearly demonstrate the absence of exsolved CO2 fluid at 3.1-6.5 GPa in ascending kimberlite magma and disprove the assimilation-fuelled buoyancy model for kimberlite magma ascent in the lithospheric mantle. We alternatively suggest that the extreme buoyancy of kimberlite magma at depths of 100-250 km is an exclusive consequence of the unique physical properties (i.e., low density, ultra-low viscosity and, thus, high mobility) of the kimberlite melt, which are dictated by its carbonatitic composition.
DS201704-0638
2017
Ohtani, E.Maeda, F., Ohtani, E., Kamada, S., Sakamaki, T., Hirao, N., Ohishi, Y.Diamond formation in the deep lower mantle: a high pressure reaction of MgCO3 and SiO2.Nature Scientific reports, Jan. 13, 7p. PdfMantleDiamond, genesis

Abstract: Diamond is an evidence for carbon existing in the deep Earth. Some diamonds are considered to have originated at various depth ranges from the mantle transition zone to the lower mantle. These diamonds are expected to carry significant information about the deep Earth. Here, we determined the phase relations in the MgCO3-SiO2 system up to 152?GPa and 3,100?K using a double sided laser-heated diamond anvil cell combined with in situ synchrotron X-ray diffraction. MgCO3 transforms from magnesite to the high-pressure polymorph of MgCO3, phase II, above 80?GPa. A reaction between MgCO3 phase II and SiO2 (CaCl2-type SiO2 or seifertite) to form diamond and MgSiO3 (bridgmanite or post-perovsktite) was identified in the deep lower mantle conditions. These observations suggested that the reaction of the MgCO3 phase II with SiO2 causes formation of super-deep diamond in cold slabs descending into the deep lower mantle.
DS201704-0647
2017
Ohtani, E.Shatskiy, A., Litasov, K.D., Sharygin, I.S., Ohtani, E.Comparison of primary kimberlite melt in a garnet lherzolite mantle source: constraints from melting phase relations in anhydrous Udachnaya-East kimberlite with variable CO2 content at 6.5GPa.Earth and Planetary Science Letters, Vol. 465, pp. 208-227.RussiaDeposit - Udachnaya-East

Abstract: The critical issue in the study of kimberlites, known as principal host rocks of diamonds, is the reconstruction of their primary melt composition, which is poorly constrained due to contamination by xenogenic materials, significant loss of volatiles during eruption, and post-magmatic alteration. It is generally accepted that the last equilibration of primary kimberlite melt with surrounding mantle (garnet lherzolite) occurred beneath cratons at 5-7 GPa (150-230 km depths). However, the subliquidus mineral assemblages obtained in kimberlite melting experiments at mantle pressures differ from lherzolite, probably owing to unaccounted loss of CO2. Here we present experiments at 6.5 GPa and 1200-1600 °C on unaltered kimberlite with an addition of 2-22 mol% CO2 over its natural abundance in the rock (13 mol%), but keeping proportions of other components identical to those in an exceptionally fresh anhydrous kimberlite from Udachnaya-East pipe in Siberia. We found that the partial melt achieves equilibrium with garnet lherzolite at 1500 °C and 19-23 mol% CO2 in the system. Under these conditions this melt contains (mol%): SiO2 = 9, FeO = 6-7, MgO = 23-26, CaO = 16, Na2O = 4, K2O = 1, and CO2 = 30-35. We propose, therefore, the alkali-rich carbonatitic composition of primary kimberlite melt and loss of 34-45 mol% (34-46 wt%) CO2 during ascent of the kimberlite magma to the surface.
DS201707-1364
2017
Ohtani, E.Sharygin, I.S., Litasov, K.D., Shatskiy, A., Safonov, O.G., Golovin, A.V., Ohtani, E., Pokhilenko, N.P.Experimental constraints on orthopyroxene dissolution in alkali-carbonate melts in the lithospheric mantle: implications for kimberlite melt composition and magma ascent.Chemical Geology, Vol. 455, pp. 44-56.Mantlekimberlite, carbonatite

Abstract: Although kimberlite magma carries large amounts of mantle-derived xenocrysts and xenoliths (with sizes up to meters), this magma ascends from the Earth's mantle (> 150–250 km) to the surface in a matter of hours or days, which enables diamonds to survive. The recently proposed assimilation-fuelled buoyancy model for kimberlite magma ascent emphasizes the importance of fluid CO2 that is produced via the reactive dissolution of mantle-derived orthopyroxene xenocrysts into kimberlite melt, which initially has carbonatitic composition. Here, we use a series of high-pressure experiments to test this model by studying the interaction of orthopyroxene (Opx) with an alkali-dolomitic melt (simplified to 0.7Na2CO3 + 0.3K2CO3 + 2CaMg(CO3)2), which is close to the melt that is produced by the partial melting of a kimberlite source, at P = 3.1–6.5 GPa and T = 1200–1600 °C, i.e., up to pressures that correspond to depths (~ 200 km) from where the ascent of kimberlite magma would start. During the first set of experiments, we study the reaction between powdered Opx and model carbonate melt in a homogeneous mixture. During the second set of experiments, we investigate the mechanism and kinetics of the dissolution of Opx crystals in alkali-dolomitic melt. Depending on the P-T conditions, Opx dissolves in the alkali-dolomitic melt (CL) either congruently or incongruently via the following reactions: Mg2Si2O6 (Opx) + CaMg(CO3)2 (CL) = CaMgSi2O6 (clinopyroxene) + 2MgCO3 (CL) and Mg2Si2O6 (Opx) = Mg2SiO4 (olivine) + SiO2 (CL). The experiments confirm that the dissolution of Opx causes gradual SiO2 enrichment in the initial carbonate melt, as previously suggested. However, the assimilation of Opx by carbonate melt does not produce fluid CO2 in the experiments because the CO2 is totally dissolved in the evolved melt. Thus, our results clearly demonstrate the absence of exsolved CO2 fluid at 3.1–6.5 GPa in ascending kimberlite magma and disprove the assimilation-fuelled buoyancy model for kimberlite magma ascent in the lithospheric mantle. We alternatively suggest that the extreme buoyancy of kimberlite magma at depths of 100–250 km is an exclusive consequence of the unique physical properties (i.e., low density, ultra-low viscosity and, thus, high mobility) of the kimberlite melt, which are dictated by its carbonatitic composition.
DS201804-0734
2018
Ohtani, E.Sharygin, I.S., Shatskiy, A., Litasov, K.D., Golovin, A.V., Ohtani, E., Pokhilenko, N.P.Interaction of peridotite with Ca-rich carbonatite melt at 3.1 and 6.5 Gpa: implications for merwinite formation in upper mantle, and for metasomatic origin of sublithospheric diamonds with Ca rich suite of inclusions.Contribution to Mineralogy and Petrology, Vol. 173, 22p.Mantlecarbonatite

Abstract: We performed an experimental study, designed to reproduce the formation of an unusual merwinite?+?olivine-bearing mantle assemblage recently described as a part of a Ca-rich suite of inclusions in sublithospheric diamonds, through the interaction of peridotite with an alkali-rich Ca-carbonatite melt, derived from deeply subducted oceanic crust. In the first set of experiments, we studied the reaction between powdered Mg-silicates, olivine and orthopyroxene, and a model Ca-carbonate melt (molar Na:K:Ca?=?1:1:2), in a homogeneous mixture, at 3.1 and 6.5 GPa. In these equilibration experiments, we observed the formation of a merwinite?+?olivine-bearing assemblage at 3.1 GPa and 1200 °C and at 6.5 GPa and 1300-1400 °C. The melts coexisting with this assemblage have a low Si and high Ca content (Ca#?=?molar 100?×?Ca/(Ca?+?Mg)?>?0.57). In the second set of experiments, we investigated reaction rims produced by interaction of the same Ca-carbonate melt (molar Na:K:Ca?=?1:1:2) with Mg-silicate, olivine and orthopyroxene, single crystals at 3.1 GPa and 1300 °C and at 6.5 GPa and 1400 °C. The interaction of the Ca-carbonate melt with olivine leads to merwinite formation through the expected reaction: 2Mg2SiO4 (olivine)?+?6CaCO3 (liquid)?=?Ca3MgSi2O8 (merwinite)?+?3CaMg(CO3)2 (liquid). Thus, our experiments confirm the idea that merwinite in the upper mantle may originate via interaction of peridotite with Ca-rich carbonatite melt, and that diamonds hosting merwinite may have a metasomatic origin. It is remarkable that the interaction of the Ca-carbonate melt with orthopyroxene crystals does not produce merwinite both at 3.1 and 6.5 GPa. This indicates that olivine grain boundaries are preferable for merwinite formation in the upper mantle.
DS201910-2311
2019
Ohtani, E.Zedgenizov, D., Kagi, H., Ohtani, E., Tsujimori, T., Komatsu, K.Inclusions of (Mg,Fe)Si03 in superdeep diamonds - former bridgmanite?Goldschmidt2019, 1p. AbstractMantlediamond inclusions

Abstract: Bridgmanite (Mg,Fe)SiO3, a high pressure silicate with a perovskite structure, is dominant material in the Lower Mantle and therefore is probably the most abundant mineral in the Earth. One single-phase and two composite inclusions of (Mg,Fe)SiO3 coexisting with jeffbenite ((Mg,Fe)3Al2Si3O12), and with jeffbenite and olivine ((Mg,Fe)2SiO4) have been analyzed to identify retrograde phases of former bridgmanite in diamonds from Juina (Brazil). XRD and Raman spectroscopy have revealed that (Mg,Fe)SiO3 inclusions are orthopyroxene at ambient conditions. XRD patterns of these inclusions indicate that they consist of polycrystals. This polycrystalline textures together with high lattice strain of host diamond around these inclusions observed from EBSD may be an evidence for the retrograde phase transition of former bridgmanite. Single-phase inclusions of (Mg,Fe)SiO3 in superdeep diamonds are suggested to represent a retrograde phase of bridgmanite and fully inherit its initial chemical composition, including a high Al and low Ni contents [1,2]. The composite inclusions of (Mg,Fe)SiO3 with jeffbenite and other silicate and oxide phases may be interpreted as exsolution products from originally homogeneous bridgmanite [3]. The bulk compositions of these inclusions are rich in Al, Ti, and Fe which are similar to bridgmanite produced in experiments on the MORB composition. However, the retrograde origin of composite inclusions due to decomposition of Al-rich bridgmanite may be doubtful because each of observed phases may represent single-phase inclusions, i.e. bridgmanite and high pressure garnet (majoritic garnet), with similar compositional features.
DS202007-1182
2020
Ohtani, E.Tanaka, R., Sakamaki, T., Ohtani, E., Fukui, H., Kamada, S., Suzuki, A., Tsutsui, S., Uchiyama, H., Baron, A.Q.R.The sound velocity of wustite at high pressures: implications for low-velocity anomalies at the base of the lower mantle.Progress in Earth and Planetary Science, Vol. 7, 23, 7p. PdfMantlewustite

Abstract: The longitudinal sound velocity (VP) and the density (?) of wüstite, FeO, were measured at pressures of up to 112.3?GPa and temperatures of up to 1700?K using both inelastic X-ray scattering and X-ray diffraction combined with a laser-heated diamond-anvil cell. The linear relationship between VP and ?, Birch’s law, for wüstite can be expressed as VP = 1.55 (1) × ? [g/cm3] - 2.03 (8) [km/s] at 300?K and VP = 1.61 (1) × ? [kg/m3] - 2.82 (10) [km/s] at 1700?K. The sound velocity of wüstite is significantly lower than that of bridgmanite and ferropericlase under lower mantle conditions. In other words, the existence of wüstite in the lower mantle can efficiently decrease the seismic velocity. Considering its slow velocity and several mechanisms for the formation of FeO-rich regions at the core-mantle boundary, we confirm earlier suggestions indicating that wüstite enrichment at the bottom of the Earth’s mantle may contribute to the formation of denser ultra-low velocity zones.
DS202007-1187
2020
Ohtani, E.Zedgenizov, D., Kagi, H., Ohtani, E., Tsujimori, T., Komatsu, K.Retrograde phases of former bridgemanite inclusions in superdeep diamonds.Lithos, in press available, 25p. PdfSouth America, Brazil, Africa, South Africa, Guinea, Canada, Northwest Territoriesdeposit - Sao Luis, Juina

Abstract: Bridgmanite (Mg,Fe)SiO3, a high pressure silicate with a perovskite structure, is dominant material in the lower mantle at the depths from 660 to 2700 km and therefore is probably the most abundant mineral in the Earth. Although synthetic analogues of this mineral have been well studied, no naturally occurring samples had ever been found in a rock on the planet’s surface except in some shocked meteorites. Due to its unstable nature under ambient conditions, this phase undergoes retrograde transformation to a pyroxene-type structure. The identification of the retrograde phase as ‘bridgmanite’ in so-called superdeep diamonds was based on the association with ferropericlase (Mg,Fe)O and other high-pressure (supposedly lower-mantle) minerals predicted from theoretical models and HP-HT experiments. In this study pyroxene inclusions in diamond grains from Juina (Brazil), one single-phase (Sample SL-14) and two composite inclusions of (Mg,Fe)SiO3 coexisting with (Mg,Fe)3Al2Si3O12 (Sample SL-13), and with (Mg,Fe)3Al2Si3O12 and (Mg,Fe)2SiO4 (Sample SL-80) have been analyzed to identify retrograde phases of former bridgmanite. XRD and Raman spectroscopy have revealed that these are orthopyroxene (Opx). (Mg,Fe)2SiO4 and (Mg,Fe)3Al2Si3O12 in these inclusions are identified as olivine and jeffbenite (TAPP). These inclusions are associated with inclusions of (Mg,Fe)O (SL-14), CaSiO3 (SL-80) and composite inclusion of CaSiO3+CaTiO3 (SL-13). XRD patterns of (Mg,Fe)SiO3 inclusions indicate that they consist of polycrystals. This polycrystalline textures together with high lattice strain of host diamond around these inclusions observed from EBSD may be an evidence for the retrograde phase transition of former bridgmanite. Single-phase inclusions of (Mg,Fe)SiO3 in superdeep diamonds are suggested to represent a retrograde phase of bridgmanite and fully inherit its initial chemical composition, including a high Al and low Ni contents [Harte, Hudson, 2013; Kaminsky, 2017]. The composite inclusions of (Mg,Fe)SiO3 with jeffbenite and other silicate and oxide phases may be interpreted as exolusion products from originally homogeneous bridgmanite [Walter et al., 2011]. The bulk compositions of these composite inclusions are rich in Al, Ti, and Fe which are similar to Al-rich bridgmanite produced in experiments on the MORB composition. However, the retrograde origin of composite inclusions due to decomposition of Al-rich bridgmanite may be doubtful because each of observed phases may represent single-phase inclusions, i.e. bridgmanite and high pressure garnet (majoritic garnet), with similar compositional features.
DS200512-0804
2004
Ohtani, L.Ohtani, L., Le Fevre, B., Vannucci, R.Direct assessment of mantle boron and lithium contents and distribution by SIMS analyses of peridotite minerals.Earth and Planetary Science Letters, Vol. 228, 1-2, Nov. 30, pp. 19-36.MantlePeridotite, pyrolitic mantle
DS200812-0669
2008
Ohtani, Y.Litasov, K.D., Ohtani, Y., Nishihara, Y., Suzuki, A., Funakoshi, K.Thermal equation of state of Al and Fe bearing phase D.Journal of Geophysical Research, Vol. 113, August 15, B08205MantleBoundary
DS201112-0754
2011
Ohuchi, T.Ohuchi, T., Kawazoe, T., Nishihara, Y., Nishiyama, N., Irifune, T.High pressure and temperature fabric transitions in olivine and variations in upper mantle seismic anisotropy.Earth and Planetary Science Letters, Vol. 304, 1-2, pp. 55-63.MantleUHP
DS201212-0531
2012
Ohuchi, T.Ohuchi, T., Kawazo, T., Nishihara, Y., Irifune, T.Change of olivine a-axis alignment by water: origin of seismic anisotropy in subduction zones.Earth and Planetary Science Letters, Vol. 317-318, pp. 111-119.MantleSubduction
DS201412-0647
2014
Ohuchi, T.Ohuchi, T., Fujino, K., Kawazoe, T., Irifune, T.Crystallographic preferred orientation of wadsleyite and ringwoodite: effects of phase transformation and water on seismic anisotropy in the mantle transition zone.Earth and Planetary Science Letters, Vol. 397, pp. 133-144.MantleMineral chemistry
DS201804-0702
2018
Ohuchi, T.Irifune, T., Ohuchi, T.Oxidation softens mantle rocks. Nature, Vol. 555, March 15, pp. 314-315.Mantlegeophysics - seismics

Abstract: Seismic waves that propagate through a layer of Earth’s upper mantle are highly attenuated. Contrary to general thinking, this attenuation seems to be strongly affected by oxidation conditions, rather than by water content.
DS201811-2597
2018
Ohuchi, T.Ohuchi, T., Lei, X., Higo, Y., Tange, Y., Sakai, T., Fujino, K.Semi-brittle behavior of wet olivine aggregates: the role of aqueous fluid in faulting at upper mantle pressures.Contributions to Mineralogy and Petrology, Vol. 173, 21p. Doi.org/10.1007/s00410-018-1515-9Mantlesubduction

Abstract: The role of aqueous fluid in fracturing in subducting slabs was investigated through a series of deformation experiments on dunite that was undersaturated (i.e., fluid-free) or saturated with water (i.e., aqueous-fluid bearing) at pressures of 1.0-1.8 GPa and temperatures of 670-1250 K, corresponding to the conditions of the shallower regions of the double seismic zone in slabs. In situ X-ray diffraction, radiography, and acoustic emissions (AEs) monitoring demonstrated that semi-brittle flow associated with AEs was dominant and the creep/failure strength of dunite was insensitive to the dissolved water content in olivine. In contrast, aqueous fluid drastically decreased the creep/failure strength of dunite (up to ~ 1 GPa of weakening) over a wide range of temperatures in the semi-brittle regime. Weakening of the dunite by the aqueous fluid resulted in the reduction of the number of AE events (i.e., suppression of microcracking) and shortening of time to failure. The AE hypocenters were located at the margin of the deforming sample while the interior of the faulted sample was aseismic (i.e., aseismic semi-brittle flow) under water-saturated conditions. A faulting (slip rate of ~ 10?³ to 10?4 s?¹) associated with a large drop of stress (?s ~ 0.5 to 1 GPa) and/or pressure (?P ~ 0.5 GPa) was dominant in fluid-free dunite, while a slow faulting (slip rate < 8 × 10?5 s?¹) without any stress/pressure drop was common in water-saturated dunite. Aseismic semi-brittle flow may mimic silent ductile flow under water-saturated conditions in subducting slabs.
DS200812-1006
2008
Ohyama, H.Santosh, M., Tsunogae, T., Ohyama, H., Sato, K., Li, J.H., Liu, S.J.Carbonic metamorphism at ultrahigh temperatures: evidence from North Chin a Craton.Earth and Planetary Science Letters, Vol. 266, 1-2, pp. 149-165.ChinaUHP
DS1900-0143
1903
Oil ReviewOil ReviewDiamond in Arctic RegionsIndus. Rec. And Oil Review., Vol. 3, No. 5, MARCH 28TH. P. 11.Canada, Ontario, Great Lakes, James Bay LowlandsGeomorphology
DS1989-0355
1989
Ojakangas, R.W.Dickas, A.B., Bornhorst, T.J., Ojakangas, R.W., Green, J.C.Lake Superior basin segment of the Midcontinent rift systemAmerican Geophysical Union (AGU) 28th. International Geological Congress Field Trip Guidebook, No. T 344, 62pMidcontinentTectonics
DS1989-1054
1989
Ojakangas, R.W.Morey, G.B., Card, K., Schulz, K., Klasner, J.S., Ojakangas, R.W.Early Proterozoic rocks of the Great Lakes regionAmerican Geophysical Union (AGU) 28th. International Geological Congress Field Trip Guidebook, No. T 145, 63pMidcontinent, Ontario, Wisconsin, MichiganSudbury structure
DS1989-1148
1989
Ojakangas, R.W.Ojakangas, R.W., Green, J.C., Holst, T.B.35th. Annual Institute on Lake Superior Geology,Proceedings andAbstracts, held Duluth Minnesota,May 4-5, 1989Institute Lake Superior Geology, 35th. VolumeMinnesota, MichiganMid continent, Tectonics
DS1991-1251
1991
Ojakangas, R.W.Ojakangas, R.W.Precambrian geology of the southern Canadian shield and the eastern BalticshieldMinnesota Geological Survey, Information Circular, No. 34, 80pMinnesota, Ontario, RussiaGeneral shield, Precambrian
DS1991-1252
1991
Ojakangas, R.W.Ojakangas, R.W., Heiskanen, K.I.Early Proterozoic glaciogenic deposits: a North America -balticconnection?Minnesota Geological Survey, Information Circular No. 34, pp. 83-91Minnesota, RussiaGeomorphology, Glacial deposits
DS1992-0874
1992
Ojakangas, R.W.Klasner, J.S., Ojakangas, R.W.Nature and style of deformation in the foreland of the early Proterozoic penokean Orogen, northern MichiganUnited States Geological Survey (USGS) Bulletin, No. 1904-K, pp. K1-K22MichiganTectonics, Penokean Orogen
DS1995-1380
1995
Ojakangas, R.W.Ojakangas, R.W., Dickas, A.B., Green, J.C.Basement tectonics - No. 10 proceedings -prev. held 1992Kluwer Academic Publ, 450pUnited States, MidcontinentStructures, lineaments, tectonics, shear zones, Table of contents
DS1997-0868
1997
Ojakangas, R.W.Ojakangas, R.W., Diackas, A.B., Green, J.C.Middle Proterozoic to Cambrian rifting, central North AmericaGeological Society of America, SPE312, 326p. approx. $ 80.00 United StatesNorth AmericaBook - ad, Tectonics, rifting
DS1997-0869
1997
Ojakangas, R.W.Ojakangas, R.W., Dickas, A.B., Green, J.C.Middle Proterozoic to Cambrian rifting central North AmericaGeological Society of America Special Paper, No. 312, $ 100.00Appalachia, MidcontinentBook - ad, Tectonics, rifting
DS1995-1381
1995
Ojala, J.Ojala, J.Targeting diamond -bearing intrusions in areas of low crustal strengthUniversity of West. Australian Key Centre, held Feb. 15, 16th., 7p.AustraliaGeophysics, Diamond pipes
DS201912-2808
2019
Oka, K.Oka, K., Hirose, K., Tagawa, S., Kidokoro, Y., Nakajima, Y., Kuwayama, Y., Morard, G., Coudurier, N., Fiquet, G.Melting in the Fe-FeO system to 204 GPa: implications for oxygen in Earth's core.American Mineralogist, Vol. 104, pp. 1603-1607.Mantlemelting

Abstract: We performed melting experiments on Fe-O alloys up to 204 GPa and 3500 K in a diamond-anvil cell (DAC) and determined the liquidus phase relations in the Fe-FeO system based on textural and chemical characterizations of recovered samples. Liquid-liquid immiscibility was observed up to 29 GPa. Oxygen concentration in eutectic liquid increased from >8 wt% O at 44 GPa to 13 wt% at 204 GPa and is extrapolated to be about 15 wt% at the inner core boundary (ICB) conditions. These results support O-rich liquid core, although oxygen cannot be a single core light element. We estimated the range of possible liquid core compositions in Fe-O-Si-C-S and found that the upper bounds for silicon and carbon concentrations are constrained by the crystallization of dense inner core at the ICB.
DS1975-0830
1978
Oka, Y.Oka, Y.Experimental Study on the Partitioning of Iron and Magnesium Between garnet and Olivine and its Applications to Kimberlites.Hokkaido University Journal of Fac. Sci., SER. 4, Vol. 18, PP. 351-376.South AfricaMineral Chemistry
DS1991-0028
1991
Okada, H.Arai, S., Okada, H.Petrology of serpentine sandstone as a key to tectonic development of serpentine beltsTectonophysics, Vol. 195, pp. 65-81JapanPeridotite -general serpentine belts, Tectonics, Petrology
DS201112-0685
2011
Okada, M.Mita, Y., Nisida, Y., Okada, M.Formation of the nitrogen B-aggregates in type Ib diamond.Goldschmidt Conference 2011, abstract p.1479.TechnologyDiamond morphology
DS2002-1179
2002
Okada, T.Okada, T., Utsumi, W., Kaneko, H., Yamakata, M., Shimomura, O.In situ observations of the decomposition of brucite diamond conversion in aqueous fluid at high pressure and temperature.Physics and Chemistry of Minerals, Vol. 29, 7, pp. 439-45.GlobalDiamond - UHP, Mineral exploration potential
DS200412-1462
2004
Okada, T.Okada, T., Utsumi, W., Kaneko, H., Turkevich, V., Hamaya, N., Shimomura, O.Kinetics of the graphite diamond transformation in aqueous fluid determined by in situ X ray diffractions at high pressures andPhysics and Chemistry of Minerals, Vol. 31, 4, pp. 261-268.TechnologyUHP
DS2001-0028
2001
OkajimaAndo, J., Shibata, Okajima, Kanagawa, Furosho, TomiolaStriped iron zoning of olivine induced discloaction creep in deformed peridotitesNature, No. 6866, Dec. 20, pp. 893-4.MantlePeridotites
DS1996-0744
1996
Okal, E.A.Kirby, S.H., Stein, S., Okal, E.A., Rubie, D.C.Metastable mantle phase transformations and deep earthquakes in subducting oceanic lithosphere.Reviews of Geophysics, Vol. 34, No. 2, May pp. 261-306.MantleLithosphere, Subduction
DS2002-1180
2002
Okamoto, K.Okamoto, K., Liou, J.G., Ogasawara, Y.Petrology of diamond grade eclogite from Kumdy KolFrontiers Science Series, University Academy Press, Vol. 38, pp. 235-256.ChinaEclogites
DS200412-1463
2002
Okamoto, K.Okamoto, K., Liou, J.G., Ogasawara, Y.Petrology of diamond grade eclogite from Kumdy Kol.Frontiers Science Series, University Academy Press, Vol. 38, pp. 235-256.ChinaEclogite
DS200612-1006
2006
Okamoto, K.Okamoto, K., Katayama, I., Maruyama, S., Liou, J.G.Zircon inclusion mineralogy of a diamond grade eclogite from the Kokchetav Massif, northern Kazakhstan.International Geology Review, Vol. 48, 10, Oct., pp. 882-891.RussiaEclogite mineralogy
DS200612-1242
2006
Okamoto, K.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
DS200512-1212
2005
Okamoto, M.Yamazaki, D., Inoue, T., Okamoto, M., Irifune, T.Grain growth kinetics of ring woodite and its implication for rheology of the subducting slab.Earth and Planetary Science Letters, Advanced in press,MantleSubduction, mantle transition zone
DS200612-1007
2005
Okamoto, T.Okamoto, T., Sumita, I., Nakakuki, T., Yoshida, S.Deformation of a partially molten D' layer by small scale convection and the resulting seismic anistrophy and ultralow velocity zone.Physics of the Earth and Planetary Interiors, Vol. 153, 1-3, pp. 32-48.MantleBoundary
DS201112-0025
2011
Okamura, H.Arai, S., Okamura, H., Kadoshima, K., Tanaka, C., Suzuki, K., Ishimaru, S.Chemical characteristics of chromian spinel in plutonic rocks: implications for deep magma processes and discrimination of tectonic setting.Island Arc, Vol. 20, 1, pp. 125-137.MantleMagmatism - tectonics
DS200512-0805
2005
Okamura, S.Okamura, S., Arculus, R.J., Martynov, Y.A.Cenozoic magmatism of the north eastern Eurasian margin: the role of lithosphere versus asthenosphere.Journal of Petrology, Vol. 46, no. 2, pp. 221-253.Europe, Baltic ShieldMagmatism - not specific to diamonds
DS200512-0806
2002
Okamura, S.Okamura, S., Mariynov, Yu.A.Cenozoic volcanism of Far East Russia: the relative importance of subcontinental lithosphere and asthenospheric mantle.Deep Seated Magmatism, magmatism sources and the problem of plumes., pp. 95-101.RussiaMagmatism
DS200812-1286
2008
OkanoYamaguchi, H.,Kudo, Y., Masuzawa, T., Kudo, M., Yamada, Takakuwa, OkanoCombine x-ray photoelectron spectroscopy/ultraviolet photoelectron spectroscopy/field emission spectroscopy for characterization of electron emmision of diamond.Journal of Vacuum Science and Technology B Microelectronics and Nanometer Structures, Vol. 26, 2, pp. 730-734. American Vacuum SocietyTechnologyDiamond emission
DS200812-1287
2008
Okano, K.Yamaguchi, H., Salto, I., Kudi, Y., Masuzawa, T., Yamada, T., Kudo, M., Takakuma, Y., Okano, K.Electron emission mechanism of hydrogeneated natural type IIb diamond (111).Diamond and Related Materials, Vol. 17, 2, pp. 162-166.TechnologyType II diamonds
DS200812-0574
2008
Okano, M.Kitawaki, H., Abduriyim, A., Okano, M.Identification of melee size synthetic yellow diamonds in jewelry.Gems & Gemology, Vol. 44, 3, pp. 202-213.TechnologySynthetics
DS201901-0044
2018
Okano, M.Kitawaki, H., Emori, K., Hisanaga, M., Yamamoto, M., Okano, M.LPHT treated pink CVD synthetic diamond.Gems & Gemology, Sixth International Gemological Symposium Vol. 54, 3, 1p. Abstract p. 267.Globalsynthetics

Abstract: Pink diamond is extremely popular among fancy-color diamonds, which has prompted numerous attempts to produce pink diamond artificially. Pink CVD synthetic diamonds appeared on the gem market around 2010. Their color was produced by a multistep process combining post-growth HPHT treatment to remove the brown hue and subsequent electron irradiation, followed by low-temperature annealing. Pink CVD synthetic diamonds treated only with low pressure and high temperature (LPHT), without additional post-growth irradiation, have also been reported but are rarely seen on the market. Recently, a loose pink stone (figure 1) was submitted to the Central Gem Laboratory in Tokyo for grading purposes. Our examination revealed that this 0.192 ct brilliant-cut marquise was a CVD synthetic diamond that had been LPHT treated. Visually, this diamond could not be distinguished from natural diamonds with similar color. However, three characteristics of CVD origin were detected: 1. C-H related absorption peaks between 3200 and 2800 cm-1, located with infrared spectroscopy 2. A luminescence peak at 737 nm, detected with photoluminescence (PL) spectroscopy 3. A trace of lamellar pattern seen in the DiamondView However, irradiation-related peaks such as at 1450 cm-1 (H1a), 741.1 nm (GR1), 594.3 nm, or 393.5 nm (ND1) that are seen in the pink CVD diamonds treated with common multi-step processes were not detected. The presence of four peaks at 3123, 2901, 2870, and 2812 cm-1 between 3200 and 2800 cm-1 suggests this stone was LPHT treated; the following observations indicate that it was not HPHT treated: 1) The 3123 cm-1 peak presumably derived from NVH0 disappears after a normal HPHT treatment. 2) The 2901, 2870, and 2812 cm-1 peaks are known to shift toward higher wavenumbers as the annealing temperature rises. Our own HPHT treatment experiments on CVDgrown diamonds proved that the 2902 and 2871 cm-1 peaks detected after 1600°C annealing shifted to 2907 and 2873 cm-1 after 2300°C annealing. The peak shift of 2901, 2870, and 2812 cm-1 is also related to the pressure during the annealing, as these peaks shifted to 2902, 2871, and 2819 cm-1 at the higher pressure of 7 GPa compared to 2900, 2868, and 2813 cm-1 at the ambient pressure under the same annealing temperature of 1600°C. 3) Absorption peaks at 7917 and 7804 cm-1 in the infrared region and at 667 and 684 nm in the visible range were also detected, which coincide with the features seen in LPHTtreated stones. From the combination of the intensity ratios of optical centers such as H3 and NV centers that were detected with PL measurement, this sample is presumed to have been treated with LPHT annealing at about 1500- 1700°C as a post-growth process. In recent years, CVD synthetic diamonds have been produced in a wider range of colors due to progress in the crystal growth techniques and post-growth treatments. Although HPHT treatment has been employed mainly to improve the color in a diamond, LPHT annealing may become widespread as the technique is further developed. Gemologists need to have deep knowledge about the optical defects in such LPHT-treated specimens.
DS1995-1479
1995
Okay, A.Perchuk, L.L., Yapaskurt, V.O., Okay, A.Comparative petrology of diamond bearing complexesPetrology, Vol. 3, No. 3, May-June pp. 238-277.RussiaPetrology, Diamond complexes
DS1992-1135
1992
Okay, A.I.Okay, A.I., Sengor, A.M.C.Evidence for intracontinental thrust related exhumation of ultra high pressure rocks in ChinaGeology, Vol. 20, No. 5, May pp. 411-414ChinaCoesite, Diamond bearing metamorphic rocks
DS1992-1706
1992
Okay, A.I.Xu, Shutong, Okay, A.I., Ji, S.Y., Sengor, A.H.C., Wen, S., LiuDiamond from the Dabie-Shaw metamorphic rocks and its implication for tectonic settingScience, Vol. 256, No. 5053, April 3, pp. 80-82ChinaMetamorphic rocks, Diamonds
DS1993-1157
1993
Okay, A.I.Okay, A.I.Petrology of a diamond and coesite bearing metamorphic terrain -Dabie @China.European Journal of Mineralogy, Vol. 5 No. 4, July-August pp. 659-675ChinaMetamorphic rocks, Diamond bearing
DS1993-1158
1993
Okay, A.I.Okay, A.I.Petrology of a diamond and coesite-bearing metamorphic terrain: Dabie @China.European Journal of Mineralogy, Vol. 5, pp. 659-675.ChinaMetamorphic rocks, Petrology
DS1993-1159
1993
Okay, A.I.Okay, A.I.Tectonics of an ultrahigh pressure metamorphic terrane: the DabieShan/Tonghai Shan Orogen, China.Tectonics, Vol. 12, No. 6, December pp. 1320-1334.ChinaTectonics, Dabie Shan area
DS1994-1301
1994
Okay, A.I.Okay, A.I.Sapphirine and Ti-Clinohumite in ultra high pressure garnet pyroxenite and eclogite from Dabie Shan, China.Contributions to Mineralogy and Petrology, Vol. 116, pp. 145-155.ChinaEclogites, Dabie Shan area
DS1994-1539
1994
Okay, A.I.Schertl, H.P., Okay, A.I.A coesite inclusion in dolomite from Dabie Shan, China: petrological and rheological significance.European Journal of Mineralogy, No. 6, pp. 995-1000.ChinaCoesite, mineralogy, Deposit -Dabie Shan area
DS1995-1382
1995
Okay, A.I.Okay, A.I.Paragonite eclogites from Dabie Shan China: re-equilibration duringexhumation?Journal of Metamorphic Geology, Vol. 13, pp. 449-460.ChinaEclogites, Geobarometry
DS1995-1669
1995
Okay, A.I.Schertl, H.P., Okay, A.I.A coesite inclusion in dolomite in Dabie Shan, China: petrological and rheological significance.European Journal of Mineralogy, Vol. 6, No. 6, Nov. 1, pp. 995-1006.ChinaCoesite, Deposit - Dabie Shan area
DS1997-0870
1997
Okay, A.I.Okay, A.I., Monie, P.Early Mesozoic subduction in the Eastern Mediterranean: evidence from Triassic eclogite in northwest Turkey.Geology, Vol. 25, No. 7, July pp. 595-598.TurkeyEclogite, Subduction zone, Subduction
DS202007-1181
2020
Okaya, D.Stern, T., Lamb, S., Moore, J.D.P., Okaya, D., Hichmuth, K.High mantle seismic P-wave speeds as a signature for gravitational spreading of superplumes. Science Adavances, Vol. 6, eaba7118 May 27, 9p. PdfAsia, Javageophysics -seismic

Abstract: New passive- and active-source seismic experiments reveal unusually high mantle P-wave speeds that extend beneath the remnants of the world’s largest known large igneous province, making up the 120-million-year-old Ontong-Java-Manihiki-Hikurangi Plateau. Sub-Moho Pn phases of ~8.8 ± 0.2 km/s are resolved with negligible azimuthal seismic anisotropy, but with strong radial anisotropy (~10%), characteristic of aggregates of olivine with an AG crystallographic fabric. These seismic results are the first in situ evidence for this fabric in the upper mantle. We show that its presence can be explained by isotropic horizontal dilation and vertical flattening due to late-stage gravitational collapse and spreading in the top 10 to 20 km of a depleted, mushroom-shaped, superplume head on a horizontal length scale of 1000 km or more. This way, it provides a seismic tool to track plumes long after the thermal effects have ceased.
DS1989-0527
1989
Okaya, D.A.Goodwin, E.B., Thompson, G.A., Okaya, D.A.Seismic identification of basement reflectors: the Bagdad reflection sequence in the Basin and Range Province- Colorado Plateau transition zone, ArizonaTectonics, Vol. 8, No. 4, August pp. 821-832Colorado PlateauTectonics
DS201902-0281
2018
Okaya, D.A.Kaminski, E., Okaya, D.A.How to detect water in the mantle wedge of a subduction zone using seismic anisotropy.Geophysical Research Letters, Vol. 45, 24, pp. 13,298-13,305.Mantlesubduction

Abstract: A subduction zone's mantle wedge can have a complex pattern of seismic anisotropy where the fast direction often rotates from trench-parallel close to the trench to trench-normal in the backarc. This pattern can be interpreted as induced by either 3-D trench-parallel flow or by the presence of water close to the trench. Almost all models so far favored the trench-parallel flow hypothesis, usually based on indirect or complementary indicators such as the evolution of geochemical signatures of volcanoes along the arc. Here we examine a seismic anisotropy observational signature that can be used to discriminate between the two explanations. The concept is defined using an interdisciplinary approach linking a direct modeling of the flow in the subduction wedge and a computation of seismic wave propagation in anisotropic media. We define a unique water-induced signature that is the presence of a “morph zone” characterized by a weak anisotropy and a decrease of seismic velocities. We apply the model to the Lau Basin where we find this predicted signature, demonstrating for the first time that water rather than trench-parallel flow is responsible for the observed anisotropy pattern there.
DS1997-0871
1997
Okaya, N.Okaya, N., Tawackoli, S., Giese, P.Area -balanced model of the late Cenozoic tectonic evolution of the central Andean arc and back arcGeology, Vol. 25, No. 4, April pp. 367-370Chile, BoliviaTectonics model, Volcanics
DS1920-0291
1926
Oke, A.L.Oke, A.L.Notes on Diamond Prospecting, Gold Coast ColonyInstitute of Mining and Metallurgy. Transactions, Vol. 35, PP. 140-154.GlobalAlluvial Diamond Placers, Jigs
DS1970-0168
1970
O'keefe, B.O'keefe, B.Diamonds Can Be DangerousPretoria: Spearhead Publn., 190P.South AfricaFiction, Kimberley
DS201512-1904
2015
O'Keefe, H.Chen, W., Leblanc, S.G., White, H.P., Milkovic, B., O'Keefe, H., Croft, B., Gunn, A., Boulanger, J.Caribou relevant environmental changes around the Ekati diamond mine measured in 2015.43rd Annual Yellowknife Geoscience Forum Abstracts, abstract p. 24.Canada, Northwest TerritoriesDeposit - Ekati

Abstract: How would a large open pit mine on caribou range (e.g., the Ekati Diamond Mine in the Bathurst caribou’s summer range) have influenced caribou? A traditional knowledge study on the cumulative impacts on the Bathurst caribou herd qualitatively described how mining activities might have influenced the herd (Mackenzie et al. 2013): caribou migration routes deflected away from the mines probably due to seeing mining activities or hearing the noises; and skinny caribou or abnormal smells and materials in caribou meat, liver, or the hide linings probably related to changes in caribou forage and quality of water and air. In other words, the potential influences of mining operations on caribou were most likely through altering what caribou can see, hear, smell (e.g., dusts and fine particle matter < 2.5 ?m (PM2.5) in the air, and from acidity in the soil), and taste (e.g., dust on foliage, vegetation composition change). Boulanger et al. (2012) estimated the size of a zone of influence (ZOI) of the Ekati-Diavik mining complex in the Bathurst caribou summer range, using caribou presence dataset. They also explored the mechanisms of ZOI using the spatial distribution of the total suspended particles, which was simulated with an atmospheric transport and dispersion model (Rescan, 2006). While these studies have added to our understanding of the possible impacts of mining operations on caribou, knowledge gaps remain. One outstanding gap is the lack of direct measurements about the caribou relevant environmental changes caused by mining operations. For example, exactly from how far away can caribou clearly see the vehicles driving on a mining road, or the buildings and the elevated waste piles in a camp? From how far away might caribou hear the noise caused by mining operations? To what spatial extent had the dusts and PM2.5 from mining operations influenced the tundra ecosystems? And how the dusts and PM2.5 from mining operations might have influenced caribou forage quality? Potentially these questions can be answered by in-situ measurements and satellite remote sensing. For example, studies have showed that it is possible to remotely sense PM2.5 distribution using twice-daily MODIS data at a spatial resolution of 1 km (Lyapustin et al., 2011; Chudnovsky et al., 2013; Hu et al., 2014). The objective of this study is thus to quantitatively measure these changes around the Ekati Diamond Mine, by means of in-situ surveys and satellite remote sensing. We conducted field surveys at more than 100 sites around the Ekati Diamond Mine during August 14-23, 2015, a collaborative effort of the NWT CIMP project entitled “Satellite Monitoring for Assessing Resource Development’s Impact on Bathurst Caribou (SMART)”, and the Dominion Diamond Ekati Corporation. In this presentation, we will report preliminary results and lessons learned from our first year’s study.
DS200612-1008
2006
O'Keefe, M.O'Keefe, M.Canadian diamond exploration - at a fork in the road to discovery.Roundup 06, Abstract p.62-63.Canada, Northwest Territories, Saskatchewan, Ontario, AlbertaNews item - overview
DS201512-1956
2015
O'Keefe, M.O'Keefe, M.Rough year creates opportunity in diamonds.Diamonds in Canada Magazine, Northern Miner, Nov. pp. 5-9.Global, CanadaDiamond industry
DS1988-0209
1988
Okereke, C.S.Fairhead, J.D., Okereke, C.S.Depths to major density contrasts beneath the West African rift system in Nigeria and Cameroon based on the spectral analysis of gravity dataJournal of African Earth Sciences, Vol. 7, No. 5-6, pp. 769-778Nigeria, Cameroon, West AfricaTectonics, Rift systems
DS1991-0465
1991
Okereke, C.S.Fairhead, J.D., Okereke, C.S., Nnange, J.M.Crustal structure of the Mamfe basin, West Africa, based on gravity @SOURCE[ TectonophysicsTectonophysics, Vol. 186, pp. 351-358West Africa, Nigeria, Benue TroughGeophysics -gravity, Tectonics
DS201012-0548
2010
Okimoto, S.Ohfuji, H., Okimoto, S., Kunimoto, T., Irifune, T.Influence of graphite crystallinity on the microtexture of polycrystalline diamond obtained by direct conversion.International Mineralogical Association meeting August Budapest, abstract p. 182.TechnologyDiamond synthesis
DS1992-1528
1992
Okita, P.Taylor, R.W., Fromm, A.J., Okita, P.Reflection surveys conducted on the western side of the Midcontinent gravity highGeological Society of America (GSA) Abstracts with programs, 1992 Annual, Vol. 24, No. 7, abstract p. A295MidcontinentGeophysics -gravity
DS1970-0377
1971
Okitaudji, R.Okitaudji, R.Contribution a l'etude des Mineraux Opaques de la Breche Kimberlitique Diamantifere de Mbuji-mayi.Louvain: Thesis, University Louvain., Democratic Republic of Congo, Central AfricaBakwanga, Kimberlite, Diamond, Ilmenite, Chromite
DS1975-0372
1976
Okitaudji, R.Okitaudji, R.La Prospection Diamantifere dans la Region de Mbuji-mayi Par la Methode des Pouvoirs Reflecteurs des Ilmenites Magnesiennes.Maadini: Sgf, Report No. P10102, No. 9, PP. 35-43.Democratic Republic of Congo, Central AfricaDiamond Prospecting
DS201012-0815
2010
Okoemova, V.Vasiliev, P., Okoemova, V., Litvin, Y., Bobrov, A.Experimental study of syngenetic relations of diamond and its inclusions in the heterogeneous system eclogite carbonatite sulfide diamond at 7.0 GPa.International Mineralogical Association meeting August Budapest, abstract p. 179.TechnologyDiamond genesis
DS201312-0545
2012
Okoemova, V.Litvin, Yu., Vasilev, P., Bobrov, A., Okoemova, V., Kuzyura, A.Parental media of natural diamonds and primary mineral inclusions in them: evidence from physicochemical experiment.Geochemistry International, Vol. 50, 9, pp. 726-759.TechnologyDiamonds inclusions
DS201112-0755
2011
Okoemova, V.Yu.Okoemova, V.Yu., Vasiliev, P.G., Kuzyura, A.V., Litvin, Yu.A., Wall, F., Jeffries, T.Experimental study of partition of rare elements between minerals and melts of diamond forming eclogite carbonatite and peridotite carbonatites systems.Goldschmidt Conference 2011, abstract p.1566.TechnologyHP
DS201112-0610
2011
Okoyomova, V.Yu.Litvin, Yu.A., Vasiliev, P.G., Bobrov, A.V., Okoyomova, V.Yu., Kuzyura, A.V.Parental media for diamonds and primary inclusions by evidence of physicochemical experiment.Vestnik ONZ RAN *** in english, 4p. IN ENGLISHMantleMantle melting - carbonatite genesis of diamond
DS2000-0276
2000
OkruginErnst, R.E., Buchan, K.L., Hamilton, Okrugin, TomshinIntegrated paleomagnetism and uranium-lead (U-Pb) geochronology of mafic dikes of Eastern Anabar Shield Region: LaurentiaJournal of Geology, Vol. 108, pp. 381-401.Russia, SiberiaMesoproterozoic paleolatitude comparison Laurentia, Geophysics - magnetics
DS201012-0721
2010
OkruginSmelov, A.P., Andreev, Altukhova, Babushkin, Bekrenev, Zaitsev.Izbekov, Koroleva, Mishmin, Okrugin, OleinkovKimberlites of the Manchary pipe: a new kimberlite field in central Yakutia.Russian Geology and Geophysics, Vol. 51, pp. 121-126.Russia, YakutiaDeposit - Manchary
DS201012-0698
2010
Okrugin, A.Shiryae, A.A., Griffin, W.L., Tomshin, M.D., Okrugin, A.Natural silicon carbide from kimberlites: polytypes, trace elements, inclusions and speculations on its origin.International Mineralogical Association meeting August Budapest, abstract p. 181.TechnologyMoissanite
DS1984-0618
1984
Okrugin, A.V.Rotman, A.J., Serenko, V.P., Okrugin, A.V., Ivanov, A.G., Makho.Garnets from Basite Explosion Pipes of Western YakutiaDoklady Academy of Sciences AKAD. NAUK SSSR., Vol. 276, No. 3, PP. 693-697.RussiaMineralogy
DS1985-0504
1985
Okrugin, A.V.Oleinikov, B.V., Pankov, V.I., Plaksenko, A.N., Okrugin, A.V.Inclusions in Moissanite from Platform Basic RocksDoklady Academy of Sciences AKAD. NAUK SSSR., Vol. 283, No. 5, PP. 1269-1273.RussiaBlank
DS1986-0679
1986
Okrugin, A.V.Rotman, A.Ya., Serenko, V.P., Okrugin, A.V., Ivanov, A.G., MakhotkoGarnets from mafic volcanic pipes of western YakutiaDoklady Academy of Science USSR, Earth Science Section, Vol. 276, January pp. 119-122RussiaMineralogy, Analyses
DS1990-1354
1990
Okrugin, A.V.Shpunt, B.R., Shamshina, E.A., Okrugin, A.V.Mineral composition of potassic alkalic volcanites of the SiberianPlatformInternational Mineralogical Association Meeting Held June, 1990 Beijing China, Vol. 2, extended abstract p. 822-823RussiaPotassic volcanites, Mineralogy
DS200612-1009
2006
Okrugin, A.V.Okrugin, A.V., Kostoyanov, A.I., Shevchenko, S.S., Lazarenkov, V.G.The model of Re-Os age of platinum group minerals from Vilyui placers in the eastern Siberian Craton.Doklady Earth Sciences, Vol. 410, 7, pp. 1044-1047.Russia, SiberiaGeochronology - not specific to diamonds
DS201607-1295
2016
Okrugin, A.V.Ernst, R.E., Hamilton, M.A., Soderlund, U., Hanes, J.A., Gladkochub, D.P., Okrugin, A.V., Kolotilina, T., Mekhonoshin, A.S., Bleeker, W., LeCheminant, A.N., Buchan, K.L., Chamberlain, K.R., Didenko, A.N.Long lived connection between southern Siberia and northern Laurentia in the Proterozoic.Nature Geoscience, Vol. 9, 6, pp. 464-469.Canada, RussiaProterozoic

Abstract: Precambrian supercontinents Nuna-Columbia (1.7 to 1.3 billion years ago) and Rodinia (1.1 to 0.7 billion years ago) have been proposed. However, the arrangements of crustal blocks within these supercontinents are poorly known. Huge, dominantly basaltic magmatic outpourings and intrusions, covering up to millions of square kilometres, termed Large Igneous Provinces, typically accompany (super) continent breakup, or attempted breakup and offer an important tool for reconstructing supercontinents. Here we focus on the Large Igneous Province record for Siberia and Laurentia, whose relative position in Nuna-Columbia and Rodinia reconstructions is highly controversial. We present precise geochronology—nine U -Pb and six Ar -Ar ages—on dolerite dykes and sills, along with existing dates from the literature, that constrain the timing of emplacement of Large Igneous Province magmatism in southern Siberia and northern Laurentia between 1,900 and 720 million years ago. We identify four robust age matches between the continents 1,870, 1,750, 1,350 and 720 million years ago, as well as several additional approximate age correlations that indicate southern Siberia and northern Laurentia were probably near neighbours for this 1.2-billion-year interval. Our reconstructions provide a framework for evaluating the shared geological, tectonic and metallogenic histories of these continental blocks.
DS1998-0471
1998
Okrugin, G.V.Garanin, V.K., Zvezdin, A.V., Okrugin, G.V.Mineralogy of oxide minerals from Morkoka pipe kimberlites (Yakutian diamond Province): implications for diamond potential evaluation.Moscow University of Geol. Bulletin., Vol. 53, No. 4, pp. 24-36.Russia, YakutiaDeposit - Morkoka
DS1990-0841
1990
Okrusch, M.Klemd, R., Matthes, S., Okrusch, M.high pressure relics in metapelitic wallrocks of the Weissenstein eclogite(Munchberg gneiss complex, Germany)Terra, Abstracts of Crustal Dynamics: Pathways and Records held Bochum FRG, Vol. 2, December p. 2GermanyEclogite, metamorphism
DS1990-1130
1990
Okrusch, M.Okrusch, M., Brockner, M.Eclogites associated with high-grade blueschists in the CycladesArchipelago, Greece- a reviewEuropean Journal of Mineralogy, Vol. 2, No. 4, pp. 451-478GlobalEclogites, Review
DS1991-1253
1991
Okrusch, M.Okrusch, M., Matthes, S., Klemd, R., O'Brien, P.J., Schmidt, K.Eclogites at the north-western margin of the Bohemian Massif: a reviewEuropean Journal of Mineralogy, Vol. 3, No. 4, pp. 707-730EuropeEclogites, Mineral chemistry
DS1993-1154
1993
Okrusch, M.O'Brien, P.J., Rohr, C., Okrusch, M., Patzak, M.Eclogite facies relics and a multistage breakdown in metabasites of the KTB pilot hole, northeast Bavaria: implications for the Variscan tectonometamorphic evolContributions to Mineralogy and Petrology, Vol. 112, pp. 261-278GlobalEclogites, metamorphism
DS1995-0561
1995
Okrusch, M.Franz, L., Brey, G.P., Okrusch, M.Metasomatic reequilibration of mantle xenoliths from the Gibeon kimberliteprovince.Proceedings of the Sixth International Kimberlite Conference Extended Abstracts, p. 169-71.NamibiaXenoliths, Blue Hills, Hanaus, Anis Kubub, Hanus, Lourentsia, Gibeon
DS1996-0466
1996
Okrusch, M.Franz, L., Brey, G.P., Okrusch, M.Reequilibration of ultramafic xenoliths from Namibia by Metasomatic processes at the mantle boundary.Journal of Geology, Vol. 104, No. 5, Sept. pp. 599-615.NamibiaMantle xenoliths, Gibeon kimberlite -Hanaus and Anis Kubub pipes
DS1996-0467
1996
Okrusch, M.Franz, L., Okrusch, M.Steady state geotherm, thermal disturbances, and tectonic development Of the lower lithosphere..GibeonContributions to Mineralogy and Petrology, Vol. 126, No. 1/2, pp. 181-198.NamibiaGeothermometry, Deposit - Gibeon kimberlite province
DS1998-1315
1998
Okrusch, M.Seth, B., Kroner, A., Okrusch, M.Archean to neoproterozoic magmatic events in the Kaoko belt of northwest Namibia and their geodynamic significance.Precambrian Research, Vol. 92, No. 4, Dec. 1, pp. 341-365.NamibiaMagmatism, Tectonics
DS2000-0990
2000
Okrusch, M.Von Seckendorff, V., Druppel, K., Okrusch, M.Oxide sulphide relationships in sodalite bearing metasomatites of the Epembe Swartbooisdrif alkaline...Min. Deposita, Vol. 35, pp. 430-50.NamibiaCarbonatite
DS2002-0406
2002
Okrusch, M.Druppel, K., Hoefs, J., Litmann, S., Okrusch, M.Carbonatite related fenitisation processes at the southern margin of the Kunene intrusive complex, NW Namibia.18th. International Mineralogical Association Sept. 1-6, Edinburgh, abstract p.250.Namibiacarbonatite - mineralogy
DS2003-0152
2003
Okrusch, M.Brandt, S., Klemd, R., Okrusch, M.Ultrahigh temperature metamorphism and multistage evolution of garnet orthopyroxeneJournal of Petrology, Vol. 44,6,pp. 1121-44.NamibiaBlank
DS200412-0200
2003
Okrusch, M.Brandt, S., Klemd, R., Okrusch, M.Ultrahigh temperature metamorphism and multistage evolution of garnet orthopyroxene granulites from the Proterozoic Epupa CompleJournal of Petrology, Vol. 44,6,pp. 1121-44.Africa, NamibiaUHP
DS200512-0248
2005
Okrusch, M.Druppel, K., Hoefs, J., Okrusch, M.Fenitizing processes induced by ferrocarbonatite magmatism at Swartbooisdrif, northwest Namibia.Journal of Petrology, Vol. 46, no. 2, pp. 377-406.Africa, NamibiaCarbonatite
DS201112-0926
2011
Okrusch, M.Schmadicke, E., Okrusch, M., Rupprecht-Gutowski, P., Will, T.M.Garnet pyroxenite, eclogite and alkremite xenoliths from the off-craton Gibeon kimberlite field, Namibia: a window into the upper mantle of the Rehoboth Terrane.Precambrian Research, In press available, 63p.Africa, NamibiaGibeon kimberlite
DS201112-0927
2011
Okrusch, M.Schmadicke, E., Okrusch, M., Rupprecht-Gutpwski, P., Will, T.M.Garnet pyroxenite, eclogite and alkremite xenoliths from the off-craton Gibeon kimberlite field, Namibia: a window into the upper mantle of Rehoboth Terrane.Precambrian Research, Vol. 191, 1-2, pp. 1-17.Africa, NamibiaEclogite, geothermometry - Gibeon
DS1993-1160
1993
Oksama, M.Oksama, M., Suppala, I.Calculation of electromagnetic anomalies of perfectly conducting bodies by integral equationsJournal of Applied Geophysics, Vol. 30, pp. 205-213GlobalMining -computer, Computer graphics
DS201506-0270
2015
Oksum, E.Gomes de Moraes Rocha, L., Bittencourt Pires, A.C., Chatck Carmelo, A., Oksum, E.Curie surface of the alkaline provinces of Goias (GAP) and Alto Paranaiba ( APAP), central Brazil.Journal of Volcanology and Geothermal Research, Vol. 297, pp. 28-38.South America, BrazilKimberlites, Lineaments
DS201012-0550
2010
Oktaybrskii, N.V.Oktaybrskii, N.V., Vladykin, A.M., Lennikov, A.A., Vrzhosek, T.A., Yasnygina, et al.Chemical composition and geochemical characteristics of the Koksharovka alkaline ultrabasic massif with carbonatites.Geochimica et Cosmochimica Acta, Vol.74, 19, pp. 778-791.Asia, RussiaCarbonatite
DS200812-0646
2008
Oktyabrsky, R.A.Lennikov, A.M., Zalisjchak, B.L., Oktyabrsky, R.A., Ivanov, V.V.Variations of chemical composition in platinum group minerals and gold of the Konder alkali ultrabasic massif, Aldan Shield, Russia.Deep Seated Magmatism, its sources and plumes, Ed. Vladykin, N.V., 2008 pp. 181-208.RussiaKonder alkaline massif
DS200912-0520
2009
Oktyabrsky, R.A.Moskalenko, E.Yu., Vladykin, N.V., Oktyabrsky, R.A.Mineral composition and features of geochemistry of the Koksharovsky massif carbonatites, Prymorye Russia.alkaline09.narod.ru ENGLISH, May 10, 2p. abstractRussiacarbonatite
DS200812-0642
2008
Okuchi, T.Lee, S.K., Lin, J.F., Cai, Y.Q., Hiraoka, N., Eng, P.J., Okuchi, T., Mao, H., Meng, Y., Hu, M.Y.,Chow, P.X ray Raman scattering study of MgSi)3 glass at high pressure: implication for triclustered MgSiO3 melt in Earth's mantle.Proceedings of National Academy of Sciences USA, Vol. 105, 23, June 10, pp. 7925-7929.MantleMelting
DS201603-0379
2015
Okuchi, T.Goncharov, A.F., Lobanov, S.S., Tan, X., Hohensee, G.T., Cahill, D.G., Lin, J-F., Thomas, S-M., Okuchi, T., Tomioka, N., Helffrich, G.Experimental study of thermal conductvity at high pressures: implication for the deep Earth's interior.Physics of the Earth and Planetary Interiors, Vol. 247, pp. 11-16.MantleExperimental Petrology

Abstract: Lattice thermal conductivity of ferropericlase and radiative thermal conductivity of iron bearing magnesium silicate perovskite (bridgmanite) - the major mineral of Earth’s lower mantle- have been measured at room temperature up to 30 and 46 GPa, respectively, using time-domain thermoreflectance and optical spectroscopy techniques in diamond anvil cells. The results provide new constraints for the pressure dependencies of the thermal conductivities of Fe bearing minerals. The lattice thermal conductivity of ferropericlase Mg0.9Fe0.1O is 5.7(6) W/(m * K) at ambient conditions, which is almost 10 times smaller than that of pure MgO; however, it increases with pressure much faster (6.1(7)%/GPa vs 3.6(1)%/GPa). The radiative conductivity of a Mg0.94Fe0.06SiO3 bridgmanite single crystal agrees with previously determined values for powder samples at ambient pressure; it is almost pressure-independent in the investigated pressure range. Our results confirm the reduced radiative conductivity scenario for the Earth’s lower mantle, while the assessment of the heat flow through the core-mantle boundary still requires in situ measurements at the relevant pressure-temperature conditions.
DS1989-1129
1989
Okuda, S.Nisida, Y., Mita, Y., Mori, K., Okuda, S., Sato, S., Yazu, S.Color centers in annealing of neutron irradiated type 1B and 1A diamondsMater. Sci. forum, Vol. 38-41, Proc.Int.defects semicond. 15th.2, 561-565GlobalDiamond morpholoyg, Irradiated
DS202009-1649
2020
Okuda, Y.Okuda, Y., Ohta, K., Haseawa, A., Yagi, T., Hirose, K., Kawaguchi, S.I., Ohishi, Y.Thermal conductivity of Fe bearing post- perovskite in the Earth's lowermost mantle.Earth and Planetary Science Letters, Vol. 547, 9p. PdfMantleperovskite

Abstract: The thermal conductivity of post-perovskite (ppv), the highest-pressure polymorph of MgSiO3 in the Earth's mantle, is one of the most important transport properties for providing better constraints on the temperature profile and dynamics at the core-mantle boundary (CMB). Incorporation of Fe into ppv can affect its conductivity, which has never been experimentally investigated. Here we determined the lattice thermal conductivities of ppv containing 3 mol% and 10 mol% of Fe at high P-T conditions - of pressures up to 149 GPa and 177 GPa, respectively, and temperatures up to 1560 K - by means of the recently developed pulsed light heating thermoreflectance technique combining continuous wave heating lasers. We found that the incorporation of Fe into ppv moderately reduces its lattice thermal conductivity as it increases the Fe content. The bulk conductivity of ppv dominant pyrolite is estimated as 1.5 times higher than that of pyrolite consisting of bridgmanite and ferropericlase in the lower mantle, which agrees with the traditional view that ppv acts as a better heat conductor than bridgmanite in the Earth's lowermost mantle.
DS1986-0618
1986
Okulitch, A.V.Okulitch, A.V., Packard, J.J, Zolnai, A.I.Evolution of the Boothia Uplift, Arctic CanadaCanadian Journal of Earth Sciences, Vol. 23, pp. 350-8.Northwest TerritoriesTectonics
DS1988-0785
1988
Okulitch, A.V.Zolnai, A.I., Okulitch, A.V.New microcomputer database system for mapsMathematical Geology, Vol. 20, No. 8, November pp. 973-976GlobalComputer, Program- Maps
DS1998-1282
1998
Okulitch, A.V.Sanford, B.V., Card, K.D., Grant, A.C., Okulitch, A.V.Bedrock geology, James Bay Ontario - District of Keewatin, NorthwestTerritories.Geological Survey of Canada Open file, No. 3558, 1:1, 000, 000 $ 26.00Ontario, Northwest TerritoriesMap - bedrock geology, James Bay Lowlands
DS200912-0831
2009
Okumura, T.Yamamoto, J.,Nakai, S., Nishimura, K., Kaneoka, I., Sato, K., Okumura, T., Prikhodko,V.S., Arai, S.Intergranular trace elements in mantle xenoliths from Russian Far East: example for mantle metasomatism by hydrous melt.Island Arc, Vol. 18, 1, pp. 225-241.RussiaMetasomatism
DS2001-0851
2001
Okuno, J.Okuno, J., Nakada, M.Effects of water load on geophysical signals due to glacial rebound and implications for mantle viscosity.Earth Planets and Space, Vol. 53, No. 12, pp. 1121-36.MantleGeophysics - seismics, Geomorphology
DS201212-0800
2012
Okura, H.Yamamoto, H., Terabayashi, M., Okura, H., Matsui, T., Kanedo, Y.Northward extrusion of the ultrahigh-pressure units in the southern Dabie metamorphic belt, east-central China.Island Arc, in press availableChinaUHP
DS201808-1744
2018
Okuschi, T.Fu, S., Yang, J., Zhang, Y., Okuschi, T., McCammon, C., Kim, H-I., Lee, S.K., Lin, J-F.Abnormal elasticity of Fe bearing bridgmanite in the Earth's lower mantle.Geophysical Research Letters, Vol. 45, 10, pp. 4725-4732.Mantlebridgmanite

Abstract: Seismic heterogeneities in the Earth's lower mantle have been attributed to thermal and/or chemical variations of constituent minerals. Bridgmanite is the most abundant lower-mantle mineral and contains Fe and Al in its structure. Knowing the effect of Fe on compressional and shear wave velocities (VP, VS) and density of bridgmanite at relevant pressure-temperature conditions can help to understand seismic heterogeneities in the region. However, experimental studies on both VP and VS of Fe-bearing bridgmanite have been limited to pressures below 40 GPa. In this study, VP and VS of Fe-bearing bridgmanite were measured up to 70 GPa in the diamond anvil cell. We observed drastic softening of VP by ~6(±1)% at 42.6-58 GPa and increased VS at pressures above 40 GPa. We interpret these observations as due to a spin transition of Fe3+. These observations are different to previous views on the effect of Fe on seismic velocities of bridgmanite. We propose that the abnormal sound velocities of Fe-bearing bridgmanite could help to explain the seismically observed low correlation between VP and VS in the mid-lower mantle. Our results challenge existing models of Fe enrichment to explain the origin of Large Low Shear Velocity provinces in the lowermost mantle.
DS200712-1063
2007
Okushi, H.Takuda, N., Saito, T., Umezawa, H., Okushi, H., Yamasaki, S.The role of boron atoms in heavily boron doped semiconducting homoepitaxial diamond growth - study of surface morphology.Diamond and Related Materials, Vol. 16, 2, Feb., pp. 409-411.TechnologyDiamond morphology
DS200712-1086
2007
Okushi, H.Tokuda, N., Saito, T., Umezawa, H., Okushi, H., Yamasaki, S.The role of boron atoms in heavily boron-doped semiconducting homoepitaxial diamond growth. Study of surface morphology.Diamond and Related Materials, Vol. 16, 2, pp. 409-411. Ingenta 1070685096TechnologyDiamond morphology
DS202002-0213
2020
Okyay, U.Okyay, U., Telling, J., Glennie, C.L., Dietrich, W.E.Airborne lidar change detection: an overview of Earth science applications. ( not specific to diamonds)Earth Science Reviews, Vol. 198, 25p. PdfGlobalLidar

Abstract: In the last two decades, airborne laser scanning (ALS) has found widespread application and driven fundamental advances in the Earth sciences. With increasing availability and accessibility, multi-temporal ALS data have been used to advance key research topics related to dynamic Earth surface processes. This review presents a comprehensive compilation of existing applications of ALS change detection to the Earth sciences. We cover a wide scope of material pertinent to the broad field of Earth sciences to encourage the cross-pollination between sub-disciplines and discuss the outlook of ALS change detection for advancing scientific discovery. While significant progress has been made in applying repeat ALS data to change detection, numerous approaches make fundamental assumptions that limit the full potential of repeat ALS data. The use of such data for 3D change detection is, therefore, in need of novel, scalable, and computationally efficient processing algorithms that transcend the ever-increasing data density and spatial coverage. Quantification of uncertainty in change detection results also requires further attention, as it is vitally important to understand what 3D differences detected between epochs represent actual change as opposed to limitations in data or methodology. Although ALS has become increasingly integral to change detection across the Earth sciences, the existence of pre- and post-event ALS data is still uncommon for many isolated hazard events, such as earthquakes, volcanic eruptions, wildfires, and landslides. Consequently, data availability is still a major limitation for many ALS change detection applications.
DS1975-0154
1975
Olagulkina, V.H.Olagulkina, V.H., Tarnovskaya, A.N.Perovskite from Yakutian KimberlitesZap. Vses. Mineral. Obshch., Vol. 104, PP. 703-710.RussiaBlank
DS1992-0010
1992
Olarewaju, V.O.Aina, A., Olarewaju, V.O.Geological interpretation of aeromagnetic dat a in some parts of North central NigeriaJournal of Africam Earth Sciences, Vol. 14, No. 1, pp. 103-109NigeriaGeophysics, Granite ring complexes
DS1990-1131
1990
Olasehinde, P.I.Olasehinde, P.I., Pal, P.C., Annor, A.E.Aeromagnetic anomalies and structural lineaments in the Nigerian BasementComplexJournal of African Earth Sciences, Vol. 11, No. 3/4, pp. 351-356NigeriaGeophysics -magnetics, Tectonics
DS1992-1136
1992
Olayinka, A.I.Olayinka, A.I.Geophysical siting of boreholes in crystalline basement areas of AfricaJournal of African Earth Sciences, Vol. 14, No. 2, February, pp. 197-208Africa, NigeriaGeophysics, Mantle, Basement
DS1997-0872
1997
Olbertz, D.Olbertz, D., Wortel, M.J.R., Hansen, U.Trench migration and subduction zone geometryGeophysical Research. Letters, Vol. 24, No. 3, Feb. 1, pp. 221-224GlobalSubduction, Tectonics
DS1989-0283
1989
Oldale, R.N.Coman, S.M., Foster, D.S., Oldale, R.N.Evidence from seismic-reflection profiles of late Wisconsinian icereadvances in the Lake Michigan basinGeological Society of America (GSA) Abstract Volume, Vol. 21, No. 4, p. 7. (abstract.)MichiganGeomorphology
DS1989-1149
1989
Oldenburg, C.M.Oldenburg, C.M., Spera, F.J., Yuen, D.A., Sewell, G.Dynamic mixing in magma bodies: theory, simulations and implicationsJournal of Geophysical Research, Vol. 94, No. B7, July 10, pp. 9215-9236GlobalMagma, Genesis
DS1999-0522
1999
Oldenburg, C.M.Oldenburg, C.M., Pruess, K.Plume separation by transient thermohaline convection in porous mediaGeophysical Research Letters, Vol. 26, No. 19, Oct. 1, pp. 2997-GlobalGeophysics, Plume - convection
DS1990-1132
1990
Oldenburg, D.Oldenburg, D.Inversion of electromagnetic data: an overview of new techniquesSurveys in Geophysics, Vol. 11, No. 2-3 September pp. 231-270GlobalGeophysics, Electromagnetic
DS201705-0868
2016
Oldenburg, D.Oldenburg, D., Kang, S., fournier, D.Airborne IP at Tli Kwi Cho.SEG Annual Meeting Dallas, 19 ppt.Canada, Northwest TerritoriesDeposit - Tli Kwi Cho
DS1970-0178
1970
Oldenburg, D.W.Porath, H., Oldenburg, D.W., Gough, D.I.Seperation of Magnetic Variation Fields and Conductive Structures in the Western United States.Geophys. Journal of Res. Astron. Soc., Vol. 19, No. 3, PP. 237-260.GlobalGeophysics, Mid-continent
DS201412-0184
2014
Oldenburg, D.W.Devriese, S.G.R., Corcoran, N., Cowan, D., Davis, K., Bild-Enkin, D., Fournier, D., Heagy, L., Kang, S., Marchant, D., McMillan, M.S., Mitchell, M., Rosenkjar, G., Yang, D., Oldenburg, D.W.Magnetic inversion of three airborne dat a sets over the Tli Kwi Cho kimberlite complex.SEG Annual Meeting Denver, pp. 1790-1794 extended abstractCanada, Northwest TerritoriesGeophysics - Tli Kwi Cho
DS201412-0250
2014
Oldenburg, D.W.Fournier, D., Heagy, L., Corcoran, N., Devriese, S.G.R., Bild-Enkin, D., Davis, K., Kang, S., Marchant, D., McMillan, M.S., Mitchell, M., Rosenkjar, G., Yang, D., Oldenburg, D.W.Multi-EM systems inversion - towards a common conductivity model for Tli Kwi Cho complex.SEG Annual Meeting Denver, pp. 1795-1798. Extended abstractCanada, Northwest TerritoriesGeophysics - Tli Kwi Cho complex
DS201501-0006
2014
Oldenburg, D.W.Devriese, S.G.R., Corcoran, N., Cowan, D., Davis, K., Bild-Enkin, D., Fournier, D., Heagy, L., Kang, S., Marchant, D., McMillan, M.S., Mitchell, M., Rosenkjar, G., Yang, D., Oldenburg, D.W.Magnetic inversion of three airborne dat a sets over the Tli Kwi Cho kimberlite complex.SEG Annual Meeting Denver, 5p. Extended abstractCanada, Northwest TerritoriesDeposit - Tli Kwi Cho, geophysics

Abstract: The magnetic and electromagnetic responses from airborne systems at Tli Kwi Cho, a kimberlite complex in the Northwest Territories, Canada, have received considerable attention over the last two decades but a complete understanding of the causative physical properties is not yet at hand. Our analysis is distributed among three papers. In the first, we find a 3D magnetic susceptibility model for the area; in the second, we find a 3D conductivity model; and in the third paper, we find a 3D chargeability model. Our goal is to explain all the geophysical results within a geologic framework. In this first paper, we invert three independent airborne magnetic data sets flown over the Tli Kwi Cho kimberlite complex located in the Lac de Gras kimberlite field in Northwest Territories, Canada. The complex consists of two kimberlites known as DO-27 and DO-18. An initial airborne DIGHEM survey was flown in 1992 and AeroTEM and VTEM data subsequently acquired in 2003 and 2004, respectively. In this paper, we invert each magnetic data set in three dimensions. Both kimberlites are recovered in each model, with DO-27 as a more susceptible body than DO-18. Our goal is to simultaneously invert the three data sets to generate a single susceptibility model for Tli Kwi Cho. This project is part of a larger, on-going investigation by UBC-GIF on inverting magnetic, electromagnetic, and induced polarization data from the Tli Kwi Cho area.
DS201501-0009
2014
Oldenburg, D.W.Fournier, D., Heagy, L., Corcoran, N., Cowan, D., Devriese, S.G.R., Bild-Enkin, D., Davis, K., Kang, S., Marchant, D., McMillan, M.S., Mitchell, M., Rosenkjar, G., Yang, D., Oldenburg, D.W.Multi-EM systems inversion - towards a common conductivity model for Tli Kwi Cho complex.SEG Annual Meeting Denver, 5p. Extended abstractCanada, Northwest TerritoriesDeposit - Tli Kwi Cho, geophysics

Abstract: The magnetic and electromagnetic responses from airborne systems at Tli Kwi Cho, a kimberlite complex in the Northwest Territories, Canada, have received considerable attention over the last two decades but a complete understanding of the causative physical properties is not yet at hand. Our analysis is distributed among three posters. In the first we find a 3D magnetic susceptibility model for the area; in the second we find a 3D conductivity model; and in the third we find a 3D chargeability model that can explain the negative transient responses measured over the kimberlite pipes. In this second paper we focus upon the task of finding a conductivity model that is compatible with three airborne data sets flown between 1992 and 2004: one frequency-domain data set (DIGHEM) and two time-domain systems (AeroTEM and VTEM). The goal is to obtain a 3D model from which geologic questions can be answered, but even more importantly, to provide a background conductivity needed to complete the 3D IP inversion of airborne EM data. We begin by modifying our pre-existing 1D frequency and time domain inversion codes to produce models that have more lateral continuity. The results are useful in their own right but we have also found that 1D analysis is often very effective in bringing to light erroneous data, assisting in estimating noise floors, and providing some starting information for developing a background model for the 3D EM inversion. Here we show some results from our Laterally Constrained Inversion (LCI) framework. The recovered conductivity models seem to agree on the general location of the kimberlite pipes but disagree on the geometry and conductivity values at depth. The complete 3D inversions in time and frequency, needed to resolved these issues, are currently in progress.
DS201611-2103
2014
Oldenburg, D.W.Devriese, S.G.R., Corcoran, N., Cowan, D., Davis, K., Bild-Enkin, D., Fournier, D., Heagy, L., Kang, S., Marchant, D., McMillan, M.S., Mitchell, M., Rosenkjar, G., Yang, D., Oldenburg, D.W.Magnetic inversion of three airborne dat a sets over the Tli Kwi Cho kimberlite complex.SEG Annual Meeting Denver, pp. 1790-1794. pdfCanada, Northwest TerritoriesDeposit - Tli Kwi Cho

Abstract: The magnetic and electromagnetic responses from airborne systems at Tli Kwi Cho, a kimberlite complex in the Northwest Territories, Canada, have received considerable attention over the last two decades but a complete understanding of the causative physical properties is not yet at hand. Our analysis is distributed among three papers. In the first, we find a 3D magnetic susceptibility model for the area; in the second, we find a 3D conductivity model; and in the third paper, we find a 3D chargeability model. Our goal is to explain all the geophysical results within a geologic framework. In this first paper, we invert three independent airborne magnetic data sets flown over the Tli Kwi Cho kimberlite complex located in the Lac de Gras kimberlite field in Northwest Territories, Canada. The complex consists of two kimberlites known as DO-27 and DO- 18. An initial airborne DIGHEM survey was flown in 1992 and AeroTEM and VTEM data subsequently acquired in 2003 and 2004, respectively. In this paper, we invert each magnetic data set in three dimensions. Both kimberlites are recovered in each model, with DO-27 as a more susceptible body than DO-18. Our goal is to simultaneously invert the three data sets to generate a single susceptibility model for Tli Kwi Cho. This project is part of a larger, on-going investigation by UBC-GIF on inverting magnetic, electromagnetic, and induced polarization data from the Tli Kwi Cho area.
DS201611-2104
2016
Oldenburg, D.W.Devriese, S.G.R., Davis, K., Oldenburg, D.W.Inversion of airborne geophysics over the Tli Kwi Cho kimberlite complex, Part I: potential fields.Tli Kwi Cho Workshop UBC, Sept. 8, 49p. Contact Canada, Northwest TerritoriesDeposit - Tli Kwi Cho
DS201611-2107
2014
Oldenburg, D.W.Fournier, D., Heagy, L., Corcoran, N., Cowan, D., Devriese, S.G.R., Bild-Enkin, D., Davis, K., Marchant, M., McMillan, M.S., Mitchell, M., Rosenkjar, G., Yang, D., Oldenburg, D.W.Multi-EM systems inversion - towards a common conductivity model for Tli Kwi Cho complex.SEG Annual Meeting Denver, pp. 1795-1799. pdfCanada, Northwest TerritoriesDeposit - Tli Kwi Cho

Abstract: The magnetic and electromagnetic responses from airborne systems at Tli Kwi Cho, a kimberlite complex in the Northwest Territories, Canada, have received considerable attention over the last two decades but a complete understanding of the causative physical properties is not yet at hand. Our analysis is distributed among three posters. In the first we find a 3D magnetic susceptibility model for the area; in the second we find a 3D conductivity model; and in the third we find a 3D chargeability model that can explain the negative transient responses measured over the kimberlite pipes. In this second paper we focus upon the task of finding a conductivity model that is compatible with three airborne data sets flown between 1992 and 2004: one frequency-domain data set (DIGHEM) and two time-domain systems (AeroTEM and VTEM). The goal is to obtain a 3D model from which geologic questions can be answered, but even more importantly, to provide a background conductivity needed to complete the 3D IP inversion of airborne EM data. We begin by modifying our pre-existing 1D frequency and time domain inversion codes to produce models that have more lateral continuity. The results are useful in their own right but we have also found that 1D analysis is often very effective in bringing to light erroneous data, assisting in estimating noise floors, and providing some starting information for developing a background model for the 3D EM inversion. Here we show some results from our Laterally Constrained Inversion (LCI) framework. The recovered conductivity models seem to agree on the general location of the kimberlite pipes but disagree on the geometry and conductivity values at depth. The complete 3D inversions in time and frequency, needed to resolved these issues, are currently in progress.
DS201611-2108
2016
Oldenburg, D.W.Fournier, D., Kang, S., McMillan, M.S., Oldenburg, D.W.Inversion of airborne geophysics over the Tli Kwi Cho kimberlite complex, Part II: electromagnetics.Tli Kwi Cho Workshop UBC, Sept. 8, 43p. Contact sdevriese @eos.ubc.caCanada, Northwest TerritoriesDeposit - Tli Kwi Cho
DS201611-2119
2015
Oldenburg, D.W.Kang, S., Fournier, D., Oldenburg, D.W.Inversion of airborne geophysics over the Tli Kwi Cho kimberlite complex.Tli Kwi Cho Workshop UBC, 24p. Contact Canada, Northwest TerritoriesDeposit - Tli Kwi Cho
DS201611-2120
2015
Oldenburg, D.W.Kang, S., Oldenburg, D.W., McMillan, M.S.3D IP Inversion of airborne EM dat a at Tli Kwi Cho.ASEG-PESA-AIG 2016 25th Geophysical Conference, 4p. PdfCanada, Northwest TerritoriesDeposit - Tli Kwi Cho

Abstract: In this study, we revisit three airborne EM surveys over Tli Kwi Cho (TKC). These consist of a frequency domain DIGHEM data set, and two time domain surveys, VTEM and AeroTEM. Negative transients have been recorded in both of the time domain surveys and we interpret these as arising from chargeable bodies. The kimberlite pipes are referred to as DO-27 and DO-18. We look in more detail at the transient data and apply the ATEM-IP inversion procedure to recover a 3D pseudo-chargeability distribution. Important components of the analysis involve estimating a background conductivity for the region. For DO-27 we have used a 3D parametric inversion to recover the conductivity from TEM data. The IP signal for the inversion is obtained by subtracting the time domain responses estimated by EM inversion from the observed background signal. This process also removes EM coupling noise that might be contaminating the data. The resultant IP data are inverted with a linear inverse approach using the sensitivity from the background conductivity. This yields a 3D model of pseudo-chargeability.
DS201804-0683
2017
Oldenburg, D.W.Devriese, S.G.R., Davis, K., Oldenburg, D.W.Inversion of airborne geophysics over the DO-27/DO18 kimberlites. Part 1. Potential fields.Society of Exploration Geophysicists, Interpretation, August T 299, 13p.Canada, Northwest Territoriesdeposit - Tli Kwi Cho

Abstract: The Tli Kwi Cho (TKC) kimberlite complex contains two pipes, called DO-27 and DO-18, which were discovered during the Canadian diamond exploration rush in the 1990s. The complex has been used as a testbed for ground and airborne geophysics, and an abundance of data currently exist over the area. We have evaluated the historical and geologic background of the complex, the physical properties of interest for kimberlite exploration, and the geophysical surveys. We have carried out 3D inversion and joint interpretation of the potential field data. The magnetic data indicate high susceptibility at DO-18, and the magnetic inversion maps the horizontal extent of the pipe. DO-27 is more complicated. The northern part is highly magnetic and is contaminated with remanent magnetization; other parts of DO-27 have a low susceptibility. Low densities, obtained from the gravity and gravity gradiometry data, map the horizontal extents of DO-27 and DO-18. We combine the 3D density contrast and susceptibility models into a single geologic model that identifies three distinct kimberlite rock units that agree with drilling data. In further research, our density and magnetic susceptibility models are combined with information from electromagnetic data to provide a multigeophysical interpretation of the TKC kimberlite complex.
DS201804-0690
2017
Oldenburg, D.W.Fournier, D., Kang, S., Mmillan, M.S., Oldenburg, D.W.Inversion of airborne geophysics over the DO-27/DO18 kimberlites. Part 2. Electromagnetics.Society of Exploration Geophysicists, Interpretation, August T 313, 13p.Canada, Northwest Territoriesdeposit - Tli Kwi Cho

Abstract: We focus on the task of finding a 3D conductivity structure for the DO-18 and DO-27 kimberlites, historically known as the Tli Kwi Cho (TKC) kimberlite complex in the Northwest Territories, Canada. Two airborne electromagnetic (EM) surveys are analyzed: a frequency-domain DIGHEM and a time-domain VTEM survey. Airborne time-domain data at TKC are particularly challenging because of the negative values that exist even at the earliest time channels. Heretofore, such data have not been inverted in three dimensions. In our analysis, we start by inverting frequency-domain data and positive VTEM data with a laterally constrained 1D inversion. This is important for assessing the noise levels associated with the data and for estimating the general conductivity structure. The analysis is then extended to a 3D inversion with our most recent optimized and parallelized inversion codes. We first address the issue about whether the conductivity anomaly is due to a shallow flat-lying conductor (associated with the lake bottom) or a vertical conductive pipe; we conclude that it is the latter. Both data sets are then cooperatively inverted to obtain a consistent 3D conductivity model for TKC that can be used for geologic interpretation. The conductivity model is then jointly interpreted with the density and magnetic susceptibility models from a previous paper. The addition of conductivity enriches the interpretation made with the potential fields in characterizing several distinct petrophysical kimberlite units. The final conductivity model also helps better define the lateral extent and upper boundary of the kimberlite pipes. This conductivity model is a crucial component of the follow-up paper in which our colleagues invert the airborne EM data to recover the time-dependent chargeability that further advances our geologic interpretation.
DS201804-0705
2017
Oldenburg, D.W.Kang, S., Fournier, D., Oldenburg, D.W.Inversion of airborne geophysics over D0-27/D0-18 kimberlites. Part 3: Induced polarization.Society of Exploration Geophysicists, Interpretation, August T 327, 14p.Canada, Northwest Territoriesdeposit -Tli Kwi Cho

Abstract: The geologically distinct DO-27 and DO-18 kimberlites, often called the Tli Kwi Cho (TKC) kimberlites, have been used as a testbed for airborne geophysical methods applied to kimberlite exploration. This paper, which is the last of a three-part series, focuses on extracting chargeability information from time-domain electromagnetic (TEM) data. Three different TEM surveys, having similar coincident-loop geometry, have been carried out over TKC. Each records negative transients over the main kimberlite units and this is a signature of induced polarization (IP) effects. By applying a TEM-IP inversion workflow to a VTEM data set we decouple the EM and IP responses in the observations and then recover 3D pseudo-chargeability models at multiple times. A subsequent analysis is used to recover Cole-Cole parameters. Our models demonstrate that both DO-18 and DO-27 pipes are chargeable, but they have different Cole-Cole time constants: 110 and 1160 µs, respectively. At DO-27, we also distinguish between two adjacent kimberlite units based on their respective Cole-Cole time constants. Our chargeability models are combined with the den-sity, magnetic susceptibility and conductivity models from Papers I and II and allow us to build a 3D petrophysical model of TKC using only information obtained from airborne geophysics. Comparison of this final petrophysical model to a 3D geological model derived from the extensive drilling program demonstrates that we can characterize the three main kimberlite units at TKC: HK, VK, and PK in 3D by using airborne geophysics.
DS1981-0325
1981
Oldershaw, A.E.Oldershaw, A.E.A Preliminary Analysis of the Mountain and Keele Diatremes, northwest Territories.Egs 1981-11, PP. 148-154.Canada, Northwest TerritoriesPetrography, Geochemistry, Analyses
DS200512-0807
2004
Oldham, D.Oldham, D., Davies, J.H.Numerical investigation of layered convection in a three dimensional shell with application to planetary mantles.Geochemistry, Geophysics, Geosystems: G3, Vol. 5, pp. Q12C04 10.1029/2004 GC000603MantleConvection, plumes
DS1860-0114
1870
Oldham, T.Oldham, T.Cuddapah and Kurnool FormationsIndia Geological Survey Records, Vol. 2, P. 9.IndiaGeology
DS1991-1254
1991
Olding, N.W.A.Olding, N.W.A., Green, D.H., Harte, B.The composition of partial melts in a volatile bearing reduced mantleProceedings of Fifth International Kimberlite Conference held Araxa June 1991, Servico Geologico do Brasil (CPRM) Special, pp. 313-315GlobalExperimental petrology, Xenoliths, partial melt composition
DS200812-0026
2008
Oldon, P.Amit, H., Aubert, J., Hulot, G., Oldon, P.A simple model for mantle driven flow at the top of Earth's core.Earth Planets and Space, Vol. 60, 8, pp. 845-854.MantleTectonics
DS1991-0660
1991
Oldow, J.S.Hansen, V.L., Ave Lallemant, H.G., Oldow, J.S.Penrose Conference Report: Transpressional tectonics of convergent platemarginsGsa Today, Vol. 1, No. 4, April pp. 73, 76GlobalTectonics, Plate margins
DS1992-0933
1992
Oldow, J.S.Leeman, W.P., Oldow, J.S., Hart, W.K.Lithosphere-scale thrusting in the western U.S. Cordillera as constrained by Sr and neodymium isotopic transitions in Neogene volcanic rocksGeology, Vol. 20, No. 1, January pp. 63-66Idaho, Oregon, NevadaGeochronology, Tectonics -thrusts
DS1995-0761
1995
Oldow, J.S.Harry, D.L., Oldow, J.S., Sawyer, D.S.The growth of orogenic belts and the role of crustal heterogeneities indecollement tectonicsGeological Society of America (GSA) Bulletin, Vol. 107, No. 12, Dec. pp. 1411-1426MantleTectonics
DS2002-1181
2002
Oldroyd, D.R.Oldroyd, D.R.The Earth inside and out: some major contributions to geology in the Twentieth Century.Geological Society of London (U.K.), 368p.$ 142.00 http://bookshop.geolsoc.org.ukGlobalBook - plate tectonics, metamorphic petrology
DS2003-1029
2003
Oldroyd, D.R.Oldroyd, D.R.The Earth inside and out: some major contributions to geology in the twentieth centuryGeological Society of London, Special Publication, 192, 360p.GlobalBook - metamorphism, geodynamics, tectonics
DS200412-1464
2003
Oldroyd, D.R.Oldroyd, D.R.The Earth inside and out: some major contributions to geology in the twentieth century.Geological Society of London, Special Publication, 192, 360p.GlobalBook - metamorphism, geodynamics, tectonics
DS1991-1255
1991
Olea, R.A.Olea, R.A., Christakos, G., David, M., Journel, A.G., Krige, D.G.Geostatistical glossary and multilingual dictionaryOxford University of Press, 288p. $ 55.95 approxGlobalGeostatistics -glossary
DS1992-1137
1992
Olea, R.A.Olea, R.A.Kriging... understanding allays intimidationGeobyte, Vol. 7, No. 5, pp. 18-23GlobalGeostatistics, Kriging
DS1996-0685
1996
Olea, R.A.Jian, X., Olea, R.A., Yu, Y.Semivariogram modeling by weighted least squaresComputers and Geosciences, Vol. 22, No. 4, pp. 379-386GlobalComputer, Program -semi variograM.
DS1975-0592
1977
O'leary, D.O'leary, D.Remote Sensing for Lineaments in the Mississippi EmbaymentEarthquake Inf. Bulletin., Vol. 9, No. 1, PP. 14-18.GlobalMid-continent
DS1995-1383
1995
O'Leary, D.M.O'Leary, D.M., Ellis, R.M., Stephenson, R.A., et al.Crustal structure of the northern Yukon and Mackenzie deltaJournal of Geophysical Research, Vol. 100, No. B6, June 10, pp. 9905-9920.Northwest Territories, YukonTectonics, Structure
DS1975-0831
1978
O'leary, D.W.O'leary, D.W., Hildenbrand, T.G.Structural Significance of Lineament and Aeromagnetic Patterns in the Mississippi Embayment.Proceedings THIRD International CONFERENCE ON BASEMENT TECTONICS, BASEMENT TECTONICS COMMITTEE No. 3, PP. 305-313.GlobalMid-continent
DS1983-0491
1983
O'leary, D.W.O'leary, D.W., Johnson, G.R., England, A.W.Fracture Detection by Airborne Microwave Radiometry in Parts of the Mississippi Embayment, Missouri and Tennessee.Remote Sensing of The Environment., Vol. 13, No. 6, DECEMBER PP. 509-524.GlobalMid-continent
DS1994-1302
1994
O'Leary, J.O'Leary, J.Mining project finance and the assessment of ore reservesGeological Society of London Mineral Resource Evaluation II, No. 79, editor Whateley, Harvey pp. 129-139GlobalGeostatistics, ore reserves, economics, Mining project finance
DS201412-0258
2014
O'Leary, J.Gaetani, G., O'Leary, J., Koga, K., Hauri, E., Rose-Koga, E., Monteleone, B.Hydration of mantle olivine under variable water and oxygen fugacity conditions.Contributions to Mineralogy and Petrology, Vol. 167, 2, pp. 1-14.MantleOlivine
DS201508-0370
2015
O'Leary, M.C.O'Leary, M.C., Lange, R.A., Ai, Y.The compressability of CaCO3-Li2CO3-Na2CO3-K2CO3 liquids: application to natrocarbonatite and CO2- bearing nephelinite liquids from Oldoinyo Lengai.Contributions to Mineralogy and Petrology, Vol. 170, 18p.Africa, TanzaniaDeposit - Oldoinyo Lengai
DS1985-0504
1985
Oleinikov, B.V.Oleinikov, B.V., Pankov, V.I., Plaksenko, A.N., Okrugin, A.V.Inclusions in Moissanite from Platform Basic RocksDoklady Academy of Sciences AKAD. NAUK SSSR., Vol. 283, No. 5, PP. 1269-1273.RussiaBlank
DS1998-1473
1998
Oleinikov, B.V.Tomshin, M.D., Fomin, A.S., Oleinikov, B.V.Basites of the Vilyui Markha zone Siberian Platform7th International Kimberlite Conference Abstract, pp. 923-5.Russia, SiberiaBilyuisk paleorift system, Dike swarm, magmatism
DS1983-0372
1983
Oleinikov, O.B.Kovalskii, V.V., Oleinikov, O.B.Native Element Minerals in the Deep Seated Xenoliths from The Obnazhonnaia Kimberlite Pipe.Doklady Academy of Sciences AKAD. NAUK SSSR., Vol. 273, No. 5, PP. 1214-1216.RussiaMineral Chemistry
DS1988-0519
1988
Oleinikov, O.B.Oleinikov, O.B., Safronov, A.F.Unusual association of chrome bearing kyanite, spinel, garnet and rutile from microxenolith of the kimberlite breccia of the Ruslovaia pipe.(Russian)Doklady Academy of Sciences Akademy Nauk SSSR, (Russian), Vol. 299, No. 4, pp. 964-969RussiaBlank
DS1991-1256
1991
Oleinikov, O.B.Oleinikov, O.B.Native metals in kimberlites of Yakutia and their genesisProceedings of Fifth International Kimberlite Conference held Araxa June 1991, Servico Geologico do Brasil (CPRM) Special, pp. 539-540RussiaNative elements, Oxides
DS1995-1384
1995
Oleinikov, O.B.Oleinikov, O.B.Mineralogy of alkaline titanates bearing kimberlite from a dike, west Ukukit kimberlite field, Yakutia.Proceedings of the Sixth International Kimberlite Conference Abstracts, pp. 404-405.Russia, YakutiaPetrography, Deposit -Ukukit An-22 dike
DS1995-1385
1995
Oleinikov, O.B.Oleinikov, O.B., Tomshin, M.D.Basite magmatism of the Yakut kimberlite provinceProceedings of the Sixth International Kimberlite Conference Abstracts, pp. 406.Russia, YakutiaMagmatism, Basite
DS1996-1053
1996
Oleinikov, O.B.Oleinikov, O.B., Safronov, A.F., Kornilova, V.P., ZaitsevA first find of melanephelinite xenolith in kimberlite rocksRussian Geology and Geophysics, Vol. 37, No. 6, pp. 54-58.Russia, YakutiaXenolith, Deposit - Obnazhennaya
DS201509-0401
2015
Oleinikov, O.B.Ionov, D.A., Carlson, R.W., Doucet, L.S., Golovin, A.V., Oleinikov, O.B.The age and history of the lithospheric mantle of the Siberian craton: Re-Os and PGE study of peridotite xenoliths from the Obnazhennaya kimberlite.Earth and Planetary Science Letters, Vol. 428, pp. 108-119.Russia, SiberiaDeposit - Obnazhennaya

Abstract: The formation age of the lithospheric mantle of the Siberian craton (one of the largest on Earth) is not well established; nearly all published whole-rock Re–Os data are for mantle xenoliths from a single kimberlite in the center of the craton (Udachnaya). We report Re–Os isotope and PGE concentration data for 19 spinel and garnet peridotite xenoliths from the Obnazhennaya kimberlite in the northeastern portion of the craton. Most samples in this study, and many Obnazhennaya peridotites in general, show a combination of relatively low Al2O3 (0.1–2%) with high CaO (1.4–4%) concentrations. Only four dunites and harzburgites in our sample suite have low contents of both Al2O3 and CaO (0.1–0.8%), but their relatively low Mg# (0.888–0.919) and highly variable Os concentrations (0.6–35 ppb) suggest they may have formed in melt migration channels rather than as residues of partial melt extraction. A group of six Ca-rich (2.0–3.2% CaO) peridotites yields the highest Re–Os model ages (mean TRD = 2.8 Ga, mean TMA = 3.5 Ga). Eight peridotites with low to moderate Al2O3 (<2%) and Mg# =0.91, including three low-Ca harzburgites, yield lower Re–Os model ages (mean TRD = 1.9 Ga, mean TMA = 2.2 Ga). The remainder of the samples may not yield meaningful TRD ages because they are not refractory (Al2O3 >2.6% and/or Mg# =0.90). We interpret these results as evidence for a two-stage formation of the lithospheric mantle. The peridotites formed at the two stages show very similar chemical compositions. The enrichment in Ca, which we attribute to widespread post-melting metasomatism by carbonate-rich melts, may have taken place either at the end of the Archean melting event, when at least one Ca–Al-rich peridotite was formed, or later. The combined Re–Os age data on xenoliths from Obnazhennaya and Udachnaya suggest that the lithospheric mantle beneath the Siberian craton was not formed in a single event, but grew in at least two events, one in the late Archean and the other in the Paleoproterozoic. This study further indicates that the formation of highly melt-depleted lithospheric mantle was not limited to the Archean, but continued well into the Paleoproterozoic when the Siberian craton was stabilized.
DS201602-0249
2015
Oleinikov, O.B.Zayakina, N.V., Oleinikov, O.B., Vasileva, T.I., Oparin, N.A.Coalingite from kimberlite breccia of the Manchary pipe, central Yakutia.Geology of Ore Deposits, Vol. 57, 8, pp. 732-736.Russia, YakutiaDeposit - Manchary

Abstract: Coalingite, Mg10Fe2(CO3)(OH)24 • 2H2O, rare Mg -Fe hydrous carbonate, has been found in the course of the mineralogical study of a disintegrated kimberlite breccia from the Manchary pipe of the Khompu -May field located in the Tamma Basin, Central Yakutia, 100 km south of Yakutsk. Coalingite occurs as small reddish brown platelets, up to 0.2 mm in size. It is associated with lizardite, chrysotile and brucite, which are typical kimberlitic assemblage. Coalingite is a supergene mineral, but in this case, it is produced by the interaction of brucite-bearing kimberlite and underground water circulating through a vertical or oblique fault zone.
DS201710-2266
2017
Oleinikov, O.B.Sobolev, N.V., Schertle, H-P., Neuser, R.D., Tomilenko, A.A., Kuzmin, D.V., Loginova, A.M., Tolstov, A.V., Kostrovitsky, S.I., Yakovlev, D.A., Oleinikov, O.B.Formation and evolution of hypabyssal kimberlites from the Siberian craton: part 1 - new insights from cathodluminescence of the carbonates. Anabar and Olenek areaJournal of Asian Earth Sciences, Vol. 145, pt. B, pp. 670-678.Russia, Siberiadeposit - Kuranakh, Kharamay
DS201802-0242
2018
Oleinikov, O.B.Ionov, D.A., Doucet, L.S., Xu, Y., Golovin, A.V., Oleinikov, O.B.Reworking of Archean mantle in the NE Siberian craton by carbonatite and silicate melt metasomatism: evidence from a carbonate bearing, dunite to web sterite xenolith suite from the Obnazhennaya kimberlite.Geochimica et Cosmochimica Acta, in press available, 46p.Russia, Siberiadeposit - Obnazhennaya

Abstract: The Obnazhennaya kimberlite in the NE Siberian craton hosts a most unusual cratonic xenolith suite, with common rocks rich in pyroxenes and garnet, and no sheared peridotites. We report petrographic and chemical data for whole rocks (WR) and minerals of 20 spinel and garnet peridotites from Obnazhennaya with Re-depletion Os isotope ages of 1.8-2.9 Ga (Ionov et al., 2015a) as well as 2 pyroxenites. The garnet-bearing rocks equilibrated at 1.6-2.8 GPa and 710-1050°C. Some xenoliths contain vermicular spinel-pyroxene aggregates with REE patterns in clinopyroxene mimicking those of garnet. The peridotites show significant scatter of Mg# (0.888-0.924), Cr2O3 (0.2-1.4 wt.%) and high NiO (0.3-0.4 wt.%). None are pristine melting residues. Low-CaO-Al2O3 (=0.9 wt.%) dunites and harzburgites are melt-channel materials. Peridotites with low to moderate Al2O3 (0.4-1.8 wt.%) usually have CaO > Al2O3, and some have pockets of calcite texturally equilibrated with olivine and garnet. Such carbonates, exceptional in mantle xenoliths and reported here for the first time for the Siberian mantle, provide direct evidence for modal makeover and Ca and LREE enrichments by ephemeral carbonate-rich melts. Peridotites rich in CaO and Al2O3 (2.7-8.0 wt.%) formed by reaction with silicate melts. We infer that the mantle lithosphere beneath Obnazhennaya, initially formed in the Mesoarchean, has been profoundly modified. Pervasive inter-granular percolation of highly mobile and reactive carbonate-rich liquids may have reduced the strength of the mantle lithosphere leading the way for reworking by silicate melts. The latest events before the kimberlite eruption were the formation of the carbonate-phlogopite pockets, fine-grained pyroxenite veins and spinel-pyroxene symplectites. The reworked lithospheric sections are preserved at Obnazhennaya, but similar processes could erode lithospheric roots in the SE Siberian craton (Tok) and the North China craton, where ancient melting residues and reworked garnet-bearing peridotites are absent.The modal, chemical and Os-isotope compositions of the Obnazhennaya xenoliths produced by reaction of refractory peridotites with melts are very particular (high Ca/Al, no Mg#-Al correlations, highly variable Cr, low 187Os/188Os, continuous modal range from olivine-rich to low-olivine peridotites, wehrlites and websterites) and distinct from those of fertile lherzolites in off-craton xenoliths and peridotite massifs. These features argue against the concept of ‘refertilization’ of cratonic and other refractory peridotites by mantle-derived melts as a major mechanism to form fertile to moderately depleted lherzolites in continental lithosphere. The Obnazhennaya xenoliths represent a natural rock series produced by ‘refertilization’, but include no rocks equivalent in modal, major and trace element to the fertile lherzolites. This study shows that ‘refertilization’ yields broad, continuous ranges of modal and chemical compositions with common wehrlites and websterites that are rare among off-craton xenoliths.
DS201902-0279
2018
Oleinikov, O.B.Ionov, D.A., Doucet, L.S., Xu, Y., Golovin, A.V., Oleinikov, O.B.Reworking of Archean mantle in the NE Siberian craton by carbonatite and silicate melt metasomatism: evidence from a carbonate bearing, dunite to websterite xenolith suite from the Obnazhennaya kimberlite.Geochimica et Cosmochimica Acta, Vol. 224, pp. 132-153.Russia, Siberiadeposit - Obnazhennaya

Abstract: The Obnazhennaya kimberlite in the NE Siberian craton hosts a most unusual cratonic xenolith suite, with common rocks rich in pyroxenes and garnet, and no sheared peridotites. We report petrographic and chemical data for whole rocks (WR) and minerals of 20 spinel and garnet peridotites from Obnazhennaya with Re-depletion Os isotope ages of 1.8-2.9?Ga (Ionov et al., 2015a) as well as 2 pyroxenites. The garnet-bearing rocks equilibrated at 1.6-2.8?GPa and 710-1050?°C. Some xenoliths contain vermicular spinel-pyroxene aggregates with REE patterns in clinopyroxene mimicking those of garnet. The peridotites show significant scatter of Mg# (0.888-0.924), Cr2O3 (0.2-1.4?wt.%) and high NiO (0.3-0.4?wt.%). None are pristine melting residues. Low-CaO-Al2O3 (=0.9?wt.%) dunites and harzburgites are melt-channel materials. Peridotites with low to moderate Al2O3 (0.4-1.8?wt.%) usually have CaO?>?Al2O3, and some have pockets of calcite texturally equilibrated with olivine and garnet. Such carbonates, exceptional in mantle xenoliths and reported here for the first time for the Siberian mantle, provide direct evidence for modal makeover and Ca and LREE enrichments by ephemeral carbonate-rich melts. Peridotites rich in CaO and Al2O3 (2.7-8.0?wt.%) formed by reaction with silicate melts. We infer that the mantle lithosphere beneath Obnazhennaya, initially formed in the Mesoarchean, has been profoundly modified. Pervasive inter-granular percolation of highly mobile and reactive carbonate-rich liquids may have reduced the strength of the mantle lithosphere leading the way for reworking by silicate melts. The latest events before the kimberlite eruption were the formation of the carbonate-phlogopite pockets, fine-grained pyroxenite veins and spinel-pyroxene symplectites. The reworked lithospheric sections are preserved at Obnazhennaya, but similar processes could erode lithospheric roots in the SE Siberian craton (Tok) and the North China craton, where ancient melting residues and reworked garnet-bearing peridotites are absent. The modal, chemical and Os-isotope compositions of the Obnazhennaya xenoliths produced by reaction of refractory peridotites with melts are very particular (high Ca/Al, no Mg#-Al correlations, highly variable Cr, low 187Os/188Os, continuous modal range from olivine-rich to low-olivine peridotites, wehrlites and websterites) and distinct from those of fertile lherzolites in off-craton xenoliths and peridotite massifs. These features argue against the concept of ‘refertilization’ of cratonic and other refractory peridotites by mantle-derived melts as a major mechanism to form fertile to moderately depleted lherzolites in continental lithosphere. The Obnazhennaya xenoliths represent a natural rock series produced by ‘refertilization’, but include no rocks equivalent in modal, major and trace element to the fertile lherzolites. This study shows that ‘refertilization’ yields broad, continuous ranges of modal and chemical compositions with common wehrlites and websterites that are rare among off-craton xenoliths.
DS201902-0280
2019
Oleinikov, O.B.Ionov, D.A., Qi, Y-H., Kang, J-T., Golovin, A.V., Oleinikov, O.B., Zheng, W., Anbar, A.D., Zhang, Z-F., Huang, F.Calcium isotopic signatures of carbonatite and silicate metasomatism, melt percolation and crustal recycling in the lithospheric mantle.Geochimica et Cosmochimica Acta, Vol. 248, pp. 1-13.Russia, Siberiacarbonatite

Abstract: Ca isotopes can be strongly fractionated at the Earth’s surface and thus may be tracers of subducted carbonates and other Ca-rich surface materials in mantle rocks, magmas and fluids. However, the d44/40Ca range in the mantle and the scope of intra-mantle isotope fractionation are poorly constrained. We report Ca isotope analyses for 22 mantle xenoliths: four basalt-hosted refractory peridotites from Tariat in Mongolia and 18 samples from the Obnazhennaya (Obn) kimberlite on the NE Siberian craton. Obn peridotites are Paleoproterozoic to Archean melting residues metasomatised by carbonate-rich and/or silicate melts including unique xenoliths that contain texturally equilibrated carbonates. d44/40Ca in 15 Obn xenoliths shows limited variation (0.74-0.97‰) that overlaps the value (0.94?±?0.05‰) inferred for the bulk silicate Earth from data on fertile lherzolites, but is lower than d44/40Ca for non-metasomatised refractory peridotites from Mongolia (1.10?±?0.03‰). Bulk d44/40Ca in four Obn peridotites containing metasomatic carbonates ranges from 0.81?±?0.08‰ to 0.83?±?0.06‰, with similar values in acid-leachates and leaching residues, indicating isotopic equilibration of the carbonates with host rocks. We infer that (a) metasomatism tends to decrease d44/40Ca values of the mantle, but its effects are usually limited (=0.3‰); (b) Ca isotopes cannot distinguish "carbonatite" and "silicate" types of mantle metasomatism. The lowest d44/40Ca value (0.56‰) was obtained for a phlogopite-bearing Obn peridotite with a very high Ca/Al of 8 suggesting that the greatest metasomatism-induced Ca isotope shifts may be seen in rocks initially low in Ca that experienced significant Ca input leading to high Ca/Al. Two Obn peridotites, a dunite (melt channel material) and a veined spinel wehrlite, have high d44/40Ca values (1.22‰ and 1.38‰), which may be due to isotope fractionation by diffusion during silicate melt intrusion and percolation in the host mantle. Overall, we find no evidence that recycling of crustal carbonates may greatly affect Ca isotope values in the global mantle or on a regional scale.
DS201903-0519
2018
Oleinikov, O.B.Ionov, D.A., Qi, Y-H., Kang, J-T., Golovin, A.V., Oleinikov, O.B., Zheng, W., Anbar, A.D., Zhang, Z-F., Huang, F.Calcium isotopic signatures of carbonatite and silicate metasomatism, melt percolation and crustal recyclying in the lithospheric mantle.Geochimica et Cosmochimica Acta, Vol. 248, pp. 1-13.Mantlecarbonatite

Abstract: Ca isotopes can be strongly fractionated at the Earth’s surface and thus may be tracers of subducted carbonates and other Ca-rich surface materials in mantle rocks, magmas and fluids. However, the d44/40Ca range in the mantle and the scope of intra-mantle isotope fractionation are poorly constrained. We report Ca isotope analyses for 22 mantle xenoliths: four basalt-hosted refractory peridotites from Tariat in Mongolia and 18 samples from the Obnazhennaya (Obn) kimberlite on the NE Siberian craton. Obn peridotites are Paleoproterozoic to Archean melting residues metasomatised by carbonate-rich and/or silicate melts including unique xenoliths that contain texturally equilibrated carbonates. d44/40Ca in 15 Obn xenoliths shows limited variation (0.74-0.97‰) that overlaps the value (0.94?±?0.05‰) inferred for the bulk silicate Earth from data on fertile lherzolites, but is lower than d44/40Ca for non-metasomatised refractory peridotites from Mongolia (1.10?±?0.03‰). Bulk d44/40Ca in four Obn peridotites containing metasomatic carbonates ranges from 0.81?±?0.08‰ to 0.83?±?0.06‰, with similar values in acid-leachates and leaching residues, indicating isotopic equilibration of the carbonates with host rocks. We infer that (a) metasomatism tends to decrease d44/40Ca values of the mantle, but its effects are usually limited (=0.3‰); (b) Ca isotopes cannot distinguish "carbonatite" and "silicate" types of mantle metasomatism. The lowest d44/40Ca value (0.56‰) was obtained for a phlogopite-bearing Obn peridotite with a very high Ca/Al of 8 suggesting that the greatest metasomatism-induced Ca isotope shifts may be seen in rocks initially low in Ca that experienced significant Ca input leading to high Ca/Al. Two Obn peridotites, a dunite (melt channel material) and a veined spinel wehrlite, have high d44/40Ca values (1.22‰ and 1.38‰), which may be due to isotope fractionation by diffusion during silicate melt intrusion and percolation in the host mantle. Overall, we find no evidence that recycling of crustal carbonates may greatly affect Ca isotope values in the global mantle or on a regional scale.
DS202006-0908
2020
Oleinikov, O.B.Afanasiev, V.P., Pokhilenko, N.P., Grinenko, V.S., Kostin, A.V., Malkovets, V.G., Oleinikov, O.B.Kimberlitic magmatism in the south western flank of the Vilui basin. ( pyrope from Kenkeme River catchment) Jurassic-Cretaceous barren kimberlites.Doklady Earth Science, Vol. 490, 2, pp. 51-54.Russiageochronology

Abstract: We have analyzed 141 grains of pyrope from Neogene sediments in a quarry of construction materials, in the Kenkeme River catchment, along its left-side tributary (Chakiya River), about 60 km northwest of Yakutsk city. The mineral chemistry patterns of pyropes are typical of Jurassic-Cretaceous barren kimberlites, like the pipes of Obnazhennaya or Muza, but are uncommon to diamondiferous Middle Paleozoic kimberlites. The results allow identifying the magmatic event and placing time constraints on kimberlite magmatism in the southeastern flank of the Vilui basin, which was part of the Late Jurassic-Early Cretaceous tectonic-magmatic event in northeastern Asia.
DS202009-1641
2020
Oleinikov, O.B.Moine, B.N., Bolfan-Casanova, N., Radu, I.B., Ionov, D.A., Costin, G., Korsakov, A.V., Golovin, A.V., Oleinikov, O.B., Deloule, E., Cottin, J.Y.Molecular hydrogen in minerals as a clue to interpret deltaD variations in the mantle. ( Omphacites from eclogites from Kaapvaal and Siberian cratons.)Nature Communications, doi:.org/10.1038/ s41467-020-17442 -8 11p. PdfAfrica, South Africa, Russia, Siberiawater

Abstract: Trace amounts of water dissolved in minerals affect density, viscosity and melting behaviour of the Earth’s mantle and play an important role in global tectonics, magmatism and volatile cycle. Water concentrations and the ratios of hydrogen isotopes in the mantle give insight into these processes, as well as into the origin of terrestrial water. Here we show the presence of molecular H2 in minerals (omphacites) from eclogites from the Kaapvaal and Siberian cratons. These omphacites contain both high amounts of H2 (70 to 460 wt. ppm) and OH. Furthermore, their ?D values increase with dehydration, suggesting a positive H isotope fractionation factor between minerals and H2-bearing fluid, contrary to what is expected in case of isotopic exchange between minerals and H2O-fluids. The possibility of incorporation of large quantities of H as H2 in nominally anhydrous minerals implies that the storage capacity of H in the mantle may have been underestimated, and sheds new light on H isotope variations in mantle magmas and minerals.
DS201012-0721
2010
OleinkovSmelov, A.P., Andreev, Altukhova, Babushkin, Bekrenev, Zaitsev.Izbekov, Koroleva, Mishmin, Okrugin, OleinkovKimberlites of the Manchary pipe: a new kimberlite field in central Yakutia.Russian Geology and Geophysics, Vol. 51, pp. 121-126.Russia, YakutiaDeposit - Manchary
DS1985-0361
1985
Oleinkov, O.B.Kovalski, V.I., Oleinkov, O.B.Native metals and natural polymineral alloys of copper, zinc,lead, tinand antimony in the rocks of the Leningrad kimberlite pipe.(Russian)Doklady Academy of Sciences Akademy Nauk SSSR, (Russian), Vol. 285, No. 1, pp. 203-208RussiaSulphides
DS201904-0749
2019
Oleinkov, O.B.Ionov, D.A., Qi, YpH., Kang, J-T., Golovin, A.V., Oleinkov, O.B., Zheng, W., Anbar, A.D., Zhang, Z-F., Huang, F.Calcium isotopic signatures of carbonatite and silicate metasomatism, melt percolation and crustal recycling in the lithospheric mantle.Geochimica et Cosmochimica Acta, Vol. 248, pp. 1-13.Mantle, Asia, Mongolia, Russia, Siberiametasomatism

Abstract: Ca isotopes can be strongly fractionated at the Earth’s surface and thus may be tracers of subducted carbonates and other Ca-rich surface materials in mantle rocks, magmas and fluids. However, the d44/40Ca range in the mantle and the scope of intra-mantle isotope fractionation are poorly constrained. We report Ca isotope analyses for 22 mantle xenoliths: four basalt-hosted refractory peridotites from Tariat in Mongolia and 18 samples from the Obnazhennaya (Obn) kimberlite on the NE Siberian craton. Obn peridotites are Paleoproterozoic to Archean melting residues metasomatised by carbonate-rich and/or silicate melts including unique xenoliths that contain texturally equilibrated carbonates. d44/40Ca in 15 Obn xenoliths shows limited variation (0.74-0.97‰) that overlaps the value (0.94?±?0.05‰) inferred for the bulk silicate Earth from data on fertile lherzolites, but is lower than d44/40Ca for non-metasomatised refractory peridotites from Mongolia (1.10?±?0.03‰). Bulk d44/40Ca in four Obn peridotites containing metasomatic carbonates ranges from 0.81?±?0.08‰ to 0.83?±?0.06‰, with similar values in acid-leachates and leaching residues, indicating isotopic equilibration of the carbonates with host rocks. We infer that (a) metasomatism tends to decrease d44/40Ca values of the mantle, but its effects are usually limited (=0.3‰); (b) Ca isotopes cannot distinguish “carbonatite” and “silicate” types of mantle metasomatism. The lowest d44/40Ca value (0.56‰) was obtained for a phlogopite-bearing Obn peridotite with a very high Ca/Al of 8 suggesting that the greatest metasomatism-induced Ca isotope shifts may be seen in rocks initially low in Ca that experienced significant Ca input leading to high Ca/Al. Two Obn peridotites, a dunite (melt channel material) and a veined spinel wehrlite, have high d44/40Ca values (1.22‰ and 1.38‰), which may be due to isotope fractionation by diffusion during silicate melt intrusion and percolation in the host mantle. Overall, we find no evidence that recycling of crustal carbonates may greatly affect Ca isotope values in the global mantle or on a regional scale.
DS1988-0520
1988
Olerud, S.Olerud, S.Davidite-loveringite in early Proterozoic albite felsite in Finnmark, north NorwayMineralogical Magazine, Vol. 52, June pp. 400-402NorwayDavidite, Loveringite
DS2002-1288
2002
OlesenPuti, M., Korikovsky, Wallbrecher, Unzog, Olesen, FritzEvolution of an eclogitized continental fragment in the Eastern Alps ( Sieggraben Austria).Journal of Structural Geology, Vol. 24, No. 1, pp. 339-57.AustriaEclogites
DS1999-0303
1999
Olesen, H.K.Helmstaedt, H.H., Olesen, H.K., Jensen, S., SchonwandtThe diamond potential of the northern margin of the North Atlantic Cratonin West Greenland.North Atlantic Mineral Symposium, Sept., abstracts pp. 169-70.Greenland, Labrador, Ungava, QuebecExploration - brief review, Craton
DS1997-0957
1997
Olesen, O.Roberts, D., Olesen, O., Karpuz, M.R.Seismo- and neotectonics in Finnmark, Kola Peninsula and the southern Barents Sea: geological framework...Tectonophysics, Vol. 270, No. 1, 2, Feb. 28, pp. 1-14.Finland, Kola PeninsulaTectonics, Geophysics - seismics
DS200712-0629
2007
Oleshko, V.Lipatov, E., Lisitsyn, V., Oleshko, V., Tarasenko, V.Spectral and kinetic characteristics of the pulsed cathodluminescence of a natural type IIa diamond.Russian Physics Journal, Vol. 50, 1, pp. 52-57.TechnologyDiamond IIa
DS200712-0627
2007
Oleshko, V.I.Lipativ, E.I., Lisitsyn, V.M., Oleshko, V.I., Tarasenko, V.F.Spectral and kinetic characteristics of the pulsed cathodluminescence of a natural IIa type diamond.Russian Physics Journal, Vol. 50, 1, pp. 51-52.TechnologyDiamond - Type IIa
DS200712-0628
2007
Oleshko, V.I.Lipativ, E.I., Lisitsyn, V.M., Oleshko, V.I., Tarasenko, V.F.Spectral and kinetic characteristics of the pulsed cathodluminescence of a natural IIa type diamond.Russian Physics Journal, Vol. 50, 1, pp. 51-52.TechnologyDiamond - Type IIa
DS2003-1404
2003
Oleynik, H.S.Valter, A.A., Oleynik, H.S., Fisenko, A.V., Semenova, I.F.Structural and morphological evidence of the impact induced development of diamondGeochemistry International, Vol. 41, 10, pp. 939-946.GlobalMeteoritic - diamond
DS2003-1405
2003
Oleynik, H.S.Valter, A.A., Oleynik, H.S., Fisenko, A.V., Semenova, L.F.Structural and morphological evidence from impact induced development of diamondGeochemistry International, Vol. 41, 10, pp. 939-46.GlobalMicromorphology - martensite transformation
DS200412-2031
2003
Oleynik, H.S.Valter, A.A., Oleynik, H.S., Fisenko, A.V., Semenova, L.F.Structural and morphological evidence from impact induced development of diamond after graphite in the Novo-Urei meteorite.Geochemistry International, Vol. 41, 10, pp. 939-46.TechnologyMicromorphology - martensite transformation
DS1987-0544
1987
Oleynikov, B.V.Oleynikov, B.V., Pankov, V.Yu., et al.Inclusions in moissanite from mafic rocks of cratonsDoklady Academy of Science USSR, Earth Science Section, Vol.283, No. 1-6, pp. 155-159.RussiaMineralogy, Craton
DS1985-0364
1985
OLEYNIKOV, O.b.Kovalskiy. v.v., OLEYNIKOV, O.b.Native metals, natural alloys polyminerals of copper zinc leadand antimony in the rocks of the Leningrad kimberlite pipe.(Russian)Doklady Academy of Sciences Akademy Nauk SSSR (Russian), Vol. 285, No.1, pp. 203-207RussiaPetrology
DS1985-0505
1985
Oleynikov, O.B.Oleynikov, O.B.Native Metal Formation in the Kimberlite Process.(russian)In: Petrologic and Geochemical Features of the Plutonic Evolution of, pp. 51-86.(Russian)RussiaBlank
DS1987-0370
1987
Oleynikov, O.B.Kovalskiy, V.V., Oleynikov, O.B.Native metals and nature polymineralic alloys of copper zinc lead tin and antimony in rocks of the Leningrad kimberlite pipeDoklady Academy of Science USSR, Earth Science Section, Vol. 285, No. 1-6, August pp. 125-129RussiaBlank
DS1987-0371
1987
Oleynikov, O.B.Kovalskiy, V.V., Oleynikov, O.B.Native metals and natural polymineralic alloys of copper, zinc, lead, tinand antimony in rocks of the Leningrad kimberlite pipeDoklady Academy of Science USSR, Earth Science Section, Vol. 285, No. 6, pp. 125-129RussiaBlank
DS201804-0673
2018
Oleynikov, O.B.Biller, A.Ya., Logvinova, A.M., Babushkina, S.A., Oleynikov, O.B., Sobolev, N.V.Shrilankite inclusions in garnets from kimberlite bodies and Diamondiferous volcanic-sedimentary rocks of the Yakutian kimberlite province, Russia.Doklady Earth Sciences, Vol. 478, 1, pp. 15-19.Russia, Yakutiadeposit - Yubileinaya

Abstract: Pyrope-almandine garnets (Mg# = 28.3-44.9, Ca# = 15.5-21.3) from a heavy mineral concentrate of diamondiferous kimberlites of the largest diamond deposit, the Yubileinaya pipe, along with kimberlite- like rocks and diamondiferous volcano-sediments of the Laptev Sea coast, have been found to contain polymineral, predominantly acicular inclusions, composed of aggregates of shrilankite (Ti2ZrO6), rutile, ilmenite, clinopyroxene, and apatite. The presence of shrilankite as an inclusion in garnets from assumed garnet-pyroxene rocks of the lower crust, lifted up by diamond-bearing kimberlite, allows it to be considered as an indicator mineral of kimberlite, which expands the possibilities when searching for kimberlite in the Arctic.
DS201809-2064
2018
Oleynikov, O.B.Logvinova, A.M., Babushkina, S.A., Oleynikov, O.B., Sobolev, N.V.Shrilankite inclusions in garnets from kimberlite bodies and Diamondiferous volcanic sedimentary rocks of the Yakutian kimberlite province.Doklady Earth Sciences, Vol. 478, 1, pp. 15-19.Russiadiamond inclusions

Abstract: Pyrope-almandine garnets (Mg# = 28.3-44.9, Ca# = 15.5-21.3) from a heavy mineral concentrate of diamondiferous kimberlites of the largest diamond deposit, the Yubileinaya pipe, along with kimberlite- like rocks and diamondiferous volcano-sediments of the Laptev Sea coast, have been found to contain polymineral, predominantly acicular inclusions, composed of aggregates of shrilankite (Ti2ZrO6), rutile, ilmenite, clinopyroxene, and apatite. The presence of shrilankite as an inclusion in garnets from assumed garnet-pyroxene rocks of the lower crust, lifted up by diamond-bearing kimberlite, allows it to be considered as an indicator mineral of kimberlite, which expands the possibilities when searching for kimberlite in the Arctic.
DS1996-0490
1996
Olezewski, W.J.Gaudette, H.E., Olezewski, W.J., Santos, J.Geochronology of Precambrian rocks from the northern part of the GuianaShield, State of RoraimaJournal of South American Earth Sciences, Vol. 9, No. 3/4, pp. 183-196BrazilGeochronology, Guiana Shield
DS201505-0240
2015
Olhede, S.C.Kalnins, L.M., Simons, F.J., Kirby, J.F., Wang, D.V., Olhede, S.C.On the robustness of estimates of mechanical anisotropy in the continental lithosphere: a North American case study and global reanalysis.Earth and Planetary Science Letters, Vol. 419, pp. 43-51.United States, CanadaTectonics
DS201812-2808
2018
Olierook, H.K.H.Farahbakhsh, E., Chandra, R., Olierook, H.K.H., Scalzo, R., Clark, C., Reddy, S.M., Muller, R.D.Computer vision based framework for extracting geological lineaments from optical remote sensing data.researchgate.com, arXiv:1810.02320v1 17p. Oct 4.Globallineaments

Abstract: The extraction of geological lineaments from digital satellite data is a fundamental application in remote sensing. The location of geological lineaments such as faults and dykes are of interest for a range of applications, particularly because of their association with hydrothermal mineralization. Although a wide range of applications have utilized computer vision techniques, a standard workflow for application of these techniques to mineral exploration is lacking. We present a framework for extracting geological lineaments using computer vision techniques which is a combination of edge detection and line extraction algorithms for extracting geological lineaments using optical remote sensing data. It features ancillary computer vision techniques for reducing data dimensionality, removing noise and enhancing the expression of lineaments. We test the proposed framework on Landsat 8 data of a mineral-rich portion of the Gascoyne Province in Western Australia using different dimension reduction techniques and convolutional filters. To validate the results, the extracted lineaments are compared to our manual photointerpretation and geologically mapped structures by the Geological Survey of Western Australia (GSWA). The results show that the best correlation between our extracted geological lineaments and the GSWA geological lineament map is achieved by applying a minimum noise fraction transformation and a Laplacian filter. Application of a directional filter instead shows a stronger correlation with the output of our manual photointerpretation and known sites of hydrothermal mineralization. Hence, our framework using either filter can be used for mineral prospectivity mapping in other regions where faults are exposed and observable in optical remote sensing data.
DS201904-0763
2019
Olierook, H.K.H.Olierook, H.K.H., Agangi, A., Plavsa, D., Reddy, S.M., Yao, W., Clark, C., Occipinti, S.A., Kylander-Clark, A.R.C.Neoproterozoic hydrothermal activity in the west Australian craton related to Rodinia assembly or breakup?Gondwana Research, Vol 68, 1, pp. 1-12.Australiacraton

Abstract: The timing of final assembly and initiation of subsequent rifting of Rodinia is disputed. New rutile ages (913?±?9?Ma, 900?±?8?Ma and 873?±?3?Ma) and published zircon, monazite, titanite, biotite, muscovite and xenotime geochronology from the Capricorn Orogen (West Australian Craton) reveal a significant early Neoproterozoic event characterized by very low to low metamorphic grade, abundant metasomatism, minor leucogranitic and pegmatitic magmatism and NW-SE fault reactivation episodes between ca. 955 and 830?Ma. Collectively, these are termed the ca. 955-830?Ma Kuparr Tectonic Event. An age range of ca. 955-830?Ma is concomitant with the final stages of Rodinia assembly and the initial stages of its attempted breakup. Very low- to low-grade metamorphic and structural geological evidence favor a distal north-south compressional regime as the driver for hydrothermal activity during ca. 955-830?Ma. Nearby continental collision or accretion from the west (e.g., South China and/or Tarim) are ruled out. The cessation of metasomatism and magmatism in the West Australian Craton after ca. 830?Ma is concomitant with the emplacement of the Gairdner-Amata dyke swarm and associated magmatic activity in South China and Laurentia, the inception of the Adelaide Rift Complex and the deposition of the Centralian Superbasin. We posit that the cessation of hydrothermal activity in the Capricorn Orogen was caused by a tectonic switch from compressional to extensional at ca. 830?Ma. Magmatic and hydrothermal fluids were transferred away from the Capricorn Orogen to the incipient Adelaide Rift Complex, terminating metasomatism in the West Australian Craton. Ultimately, the Kuparr Tectonic Event marked the final stages of Rodinia assembly and its cessation marks the initial stages of its attempted breakup.
DS201905-1028
2018
Olierook, H.K.H.Farahbakhsh, E., Chandra, R., Olierook, H.K.H., Scalzo, R., Clark, C., Reddy, S.M., Muller, R.D.Computer vision based framework for extracting geological lineaments from optical remote sensing data.arXiv.1810,02320vl, researchgate 17p.Australialineaments
DS202008-1384
2020
Olierook, H.K.H.Doucet, L.S., Li, Z-X., Gamel El Dien, H., Pourteau, A., Murphy, B., Collins, W.J., Mattielli, N., Olierook, H.K.H., Spencer, C.J., Mitchell, R.N.Distinct formation history for deep mantle domains reflected in geochemical differences.Nature Geoscience, Vol. 13, pp. 511-515. pdfMantlegeochemistry

Abstract: The Earth’s mantle is currently divided into the African and Pacific domains, separated by the circum-Pacific subduction girdle, and each domain features a large low shear-wave velocity province (LLSVP) in the lower mantle. However, it remains controversial as to whether the LLSVPs have been stationary through time or dynamic, changing in response to changes in global subduction geometry. Here we compile radiogenic isotope data on plume-induced basalts from ocean islands and oceanic plateaus above the two LLSVPs that show distinct lead, neodymium and strontium isotopic compositions for the two mantle domains. The African domain shows enrichment by subducted continental material during the assembly and breakup of the supercontinent Pangaea, whereas no such feature is found in the Pacific domain. This deep-mantle geochemical dichotomy reflects the different evolutionary histories of the two domains during the Rodinia and Pangaea supercontinent cycles and thus supports a dynamic relationship between plate tectonics and deep-mantle structures.
DS202009-1625
2020
Olierook, H.K.H.Doucet, L.S., Li, Z-X., GamelEl Dien, H., Pourteau, A., Murphy, J.B., Collins, W.J., Mattielli, N., Olierook, H.K.H., Spencer, C.J., Mitchell, R.N.Distinct formation history for deep mantle domains reflected in geochemical differences.Nature Geoscience, Vol. 13, July pp. 511-515. pdfMantlegeochemistry

Abstract: The Earth’s mantle is currently divided into the African and Pacific domains, separated by the circum-Pacific subduction girdle, and each domain features a large low shear-wave velocity province (LLSVP) in the lower mantle. However, it remains controversial as to whether the LLSVPs have been stationary through time or dynamic, changing in response to changes in global subduction geometry. Here we compile radiogenic isotope data on plume-induced basalts from ocean islands and oceanic plateaus above the two LLSVPs that show distinct lead, neodymium and strontium isotopic compositions for the two mantle domains. The African domain shows enrichment by subducted continental material during the assembly and breakup of the supercontinent Pangaea, whereas no such feature is found in the Pacific domain. This deep-mantle geochemical dichotomy reflects the different evolutionary histories of the two domains during the Rodinia and Pangaea supercontinent cycles and thus supports a dynamic relationship between plate tectonics and deep-mantle structures.
DS2000-0994
2000
Olijnk, H.Wain, A., Waters, D., Jephcoat, A., Olijnk, H.The high pressure to ultrahigh pressure eclogite transition in the Western Gneiss region, Norway.European Journal of Mineralogy, No. 3, pp. 667-88.NorwayEclogite, ultra high pressure (UHP)
DS2002-1182
2002
Olijnyk, Z.Olijnyk, Z.Billion dollar babies... the rush is on, as junior miners like Kensington race for riches in Canada's burgeoning diamond industry. Jellicoe - interview.Canadian Business, September 30, pp.32-36.SaskatchewanNews item, Kensington Resources
DS2000-0995
2000
Olijynk, H.Wain, A., Waters, D., Olijynk, H.The high pressure to ultra high pressure eclogite transition in the Western Gneiss region, Norway.European Journal of Mineralogy, Vol. 12, No. 3, May 1, pp. 667-NorwayMineralogy, ultra high pressure (UHP)
DS201212-0589
2009
Olimpio Goncalves, A.Robles-Cruz, S., Lomba, A., Melgarejo, J-C., Gali, S., Olimpio Goncalves, A.The Cucumbi kimberlite, NE Angola: problems to discriminate fertile and barren kimberlites.Revist de la Sociedad de Mineralogia ( in english), pp. 159-160.Africa, AngolaDeposit - Cucumbi
DS200912-0635
2009
Olimpo, A.Robles-Cruz, S.E., Watangua, M., Isidoro, l., Melgarejo, J.C., Gali, S., Olimpo, A.Contrasting compositions and textures of ilmenite in the Catoca kimberlite, Angola, and implications in exploration for diamond.Lithos, In press - available formatted 10p.Africa, AngolaDeposit - Catoca
DS201905-1056
2019
Oliva, S.J.Lavayssiere, A., Drooff, C., Ebinger, C., Gallacher, R., Illsley-Kemp, F., Finnigan, Oliva, S.J., Keir, D.Deep extent and kinematics of faulting in the southern Tanganyika Rift, Africa.Tectonics, Vol. 38, 3, pp. 842-862.Africarifting

Abstract: Unusually deep earthquakes occur beneath rift segments with and without surface expressions of magmatism in the East African Rift system. The Tanganyika rift is part of the Western rift and has no surface evidence of magmatism. The TANG14 array was deployed in the southern Tanganyika rift, where earthquakes of magnitude up to 7.4 have occurred, to probe crust and upper mantle structure and evaluate fault kinematics. Four hundred seventy-four earthquakes detected between June 2014 and September 2015 are located using a new regional velocity model. The precise locations, magnitudes, and source mechanisms of local and teleseismic earthquakes are used to determine seismogenic layer thickness, delineate active faults, evaluate regional extension direction, and evaluate kinematics of border faults. The active faults span more than 350 km with deep normal faults transecting the thick Bangweulu craton, indicating a wide plate boundary zone. The seismogenic layer thickness is 42 km, spanning the entire crust beneath the rift basins and their uplifted flanks. Earthquakes in the upper mantle are also detected. Deep earthquakes with steep nodal planes occur along subsurface projections of Tanganyika and Rukwa border faults, indicating that large offset (=5 km) faults penetrate to the base of the crust, and are the current locus of strain. The focal mechanisms, continuous depth distribution, and correlation with mapped structures indicate that steep, deep border faults maintain a half-graben morphology over at least 12 Myr of basin evolution. Fault scaling based on our results suggests that M > 7 earthquakes along Tanganyika border faults are possible.
DS1997-0873
1997
Olive, V.Olive, V., Ellam, R.M., Harte, B.A Re Os isotope study of ultramafic xenoliths from the Matsoku kimberliteEarth and Planetary Science Letters, Vol. 150, No. 1-2, July pp. 129-140.GlobalGeochronology, Deposit - Matsoku
DS201905-1062
2019
Oliveira, B.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.
DS202002-0219
2020
Oliveira, B.Tilhac, R., Oliveira, B., Griffin, W.L., O'Reilly, S.Y., Schaefer, B.F., Alard, O., Ceuleneer, G., Afonso, J.C., Gregoire, M.Reworking of old continental lithosphere: unradiogenic Os and decoupled Hf-Nd isotopes in sub-arc mantle pyroxenites.Lithos, Vol. 354-355, 19p. pdfEurope, Spainpyroxenites

Abstract: Mantle lithologies in orogenic massifs and xenoliths commonly display strikingly different Hf- and Nd-isotope compositions compared to oceanic basalts. While the presence of pyroxenites has long been suggested in the source region of mantle-derived magmas, very few studies have reported their combined HfNd isotope compositions. We here report the first LuHf data along with ReOs data and S concentrations on the Cabo Ortegal Complex, where the pyroxenite-rich Herbeira massif has been interpreted as remnants of a delaminated arc root. The pyroxenites, chromitites and their host harzburgites show a wide range of whole-rock 187Re/188Os and 187Os/188Os (0.16-1.44), indicating that Re was strongly mobilized, partly during hydrous retrograde metamorphism but mostly during supergene alteration that preferentially affected low-Mg#, low Cu/S pyroxenites. Samples that escaped this disturbance yield an isochron age of 838 ± 42 Ma, interpreted as the formation of Cabo Ortegal pyroxenites. Corresponding values of initial 187Os/188Os (0.111-0.117) are relatively unradiogenic, suggesting limited contributions of slab-derived Os to primitive arc melts such as those parental to these pyroxenites. This interpretation is consistent with radiogenic Os in arc lavas being mostly related to crustal assimilation. Paleoproterozoic to Archean Os model ages confirm that Cabo Ortegal pyroxenites record incipient volcanic arc magmatism on the continental margin of the Western African Craton, as notably documented by zircon UPb ages of 2.1 and 2.7 Ga. LuHf data collected on clinopyroxene and amphibole separates and whole-rock samples are characterized by uncorrelated 176Lu/177Hf and 176Hf/177Hf (0.2822-0.2855), decoupled from Nd-isotope compositions. This decoupling is ascribed to diffusional disequilibrium during melt-peridotite interaction, in good agreement with the results of percolation-diffusion models simulating the interaction of an arc melt with an ancient melt-depleted residue. These models notably show that HfNd isotopic decoupling such as recorded by Cabo Ortegal pyroxenites and peridotites (??Hf(i) up to +97) is enhanced during melt-peridotite interaction by slow diffusional re-equilibration and can be relatively insensitive to chromatographic fractionation. Finally, we discuss the hypothesis that arc-continent interaction may provide preferential conditions for such isotopic decoupling and propose that its ubiquitous recognition in peridotites reflects the recycling of sub-arc mantle domains derived from ancient, reworked SCLM.
DS202007-1161
2020
Oliveira, B.Lu, J., Tilhac, R., Griffin, W.L., Zheng, J.P., Xiong, Q., Oliveira, B., O'Reilly, S.Y.Lithospheric memory of subduction in mantle pyroxenite xenoliths from rift related basalts.Earth and Planetary Science Letters, Vol. 544, 116365 14p. PdfAustraliacarbonatite

Abstract: Petrological and geochemical studies have revealed the contribution of garnet pyroxenites in basalt petrogenesis. However, whether primary mantle melts are produced with such signature or acquired it subsequently remains somewhat controversial. We here integrate new major-, trace-element and Sr-Nd-Hf isotopic compositions of garnet pyroxenite xenoliths in Holocene alkali basalts from Lakes Bullenmerri and Gnotuk, Southeastern Australia, to relate their petrogenesis to mantle-wedge melt circulation and subsequent lithospheric evolution. Results show that the clinopyroxenites have lower MgO and Cr2O3 contents than the associated websterites, and range in compositions from depleted LREE patterns and highly radiogenic Nd and Hf isotopic signatures in relatively low-MgO samples (Type 1), to enriched REE patterns with negative HFSE anomalies, unradiogenic Nd and Hf isotopes, and extremely radiogenic Sr-isotopic ratios in samples with higher MgO (Type 2). Such compositional variabilities suggest that these pyroxenites represent segregates from melts derived from a recycled oceanic lithosphere with a potential contribution from pelagic sediments. Variable LREE contents and isotopic compositions between those of Type 1 and 2 clinopyroxenites are observed in amphibole-bearing samples (Type 3), which are interpreted as Type 1-like protoliths metasomatized by the basaltic and carbonatitic melts, possibly parental to Type 2 clinopyroxenites. The lithosphere beneath Southeastern Australia thus has received variable melt contributions from a heterogeneous mantle-wedge source, which notably includes a subducted oceanic slab package that has retained its integrity during subduction. On this basis, we suggest that the compositional heterogeneity and temporal evolution of the subsequent Southeastern Australian basaltic magmatism were probably affected by the presence of pyroxenite fragments in the basalt source and formed by the tectonic reactivation of this lithosphere during Cenozoic rifting. This interpretation is notably consistent with a trend of Nd-Pb isotopes towards EMII in Older Volcanic Provinces (OVP basalts) and limited Sr-Nd-Pb isotopic variations towards HIMU in the Newer Volcanic Provinces (NVP basalts, including the host lavas), which also exhibit low SiO2, high FeO and high CaO/Al2O3 commonly interpreted as due to pyroxenite contributions. Therefore, the identification of a subduction signature in these rift-related lavas attests to a "lithospheric memory" of earlier subduction episodes (as documented by the xenoliths), rather than a reflection of contemporaneous subduction tectonics.
DS200512-0442
2005
Oliveira, D.C.Hollanda, M.H.B.M., Pimentel, M.M., Oliveira, D.C., De Sa, E.F.J.Lithosphere - asthenosphere interaction and the origin of Cretaceous tholeiitic magmatism in northeastern Brazil: Sr Nd Pb isotopic evidence.Lithos, Advanced in press,South America, BrazilRio Ceara Mirim dike, magmatism
DS201901-0084
2019
Oliveira, D.C.Teixeira, W., Reis, N.J., Bettencourt, J.S., Klein, E.L., Oliveira, D.C.Intraplate Proterozoic magmatism in the Amazonian craton reviewed: geochronology, crustal tectonics and global barcode matches.Dyke Swarms of the World: a modern perspective Ed. Srivastava et al. Springer , Chapter pp. 111-154. availableSouth America, Guiana, Brazilcraton

Abstract: We review geochronological data including U-Pb baddelyite ages of Proterozoic mafic dyke swarms and sills of the Amazonian Craton, as well as their geochemical character and geological settings, in order to arrive at an integrated tectonic interpretation. The information together with the characteristics of coeval volcanic-plutonic suites indicates a cyclicity of the mafic-felsic activity through time and space. At least four LIP/SLIP events are apparent, and each one appears to accompany the stepwise accretionary crustal growth of Amazonia. The oldest two, the Orocaima (1.98-1.96 Ga) and Uatumã (c. 1.89-1.87 Ga) SLIPs, comprise calc-alkaline I-type and subordinate A-type plutonic and volcanic rocks. Synchronous mafic intraplate activity occurs across the Guiana and Central-Brazil Shields. These two events may be caused by interaction between subduction-related processes and mantle plumes with synchronous lithosphere extension during the two time periods. The Avanavero (1.79 Ga) LIP event mostly consists of mafic dykes and sills which are intrusive into the Roraima platform cover, in the Guiana Shield. They show tholeiitic chemistry and similarities with E-MORB and subcontinental lithospheric mantle-derived basalts, whereas the REE pattern suggests affinity with intraplate settings. The age of the Avanavero rocks is identical to the Crepori Diabase, located ca. 1800 km away to the south (Central-Brazil Shield). The youngest LIP event (1.11 Ga), the Rincón del Tigre-Huanchaca, has the Rio Perdido Suite as a component in the Rio Apa Terrane, which is ca. 300 km away from the Rincón del Tigre Complex, located in the SW portion of the Amazonian Craton. Furthermore, the Central-Brazil and Guiana Shields boasts widespread intraplate mafic activity, highlighted by the Mata-Matá (1.57 Ga), Salto do Céu (1.44 Ga) and Nova Floresta (1.22 Ga) mafic sills and the Cachoeira Seca Troctolite (1.19 Ga). Contemporaneous A-type, rapakivi granites with roughly similar ages also occur elsewhere. These particular episodes are extension specific steps of the Mesoproterozoic Amazonia, and the quite large distribution is consistent with LIP events. In a broader perspective, the intermittent Proterozoic intracratonic activity has a barcode that matches LIP/SLIP events in Columbia and Rodinia.
DS201911-2570
2019
Oliveira, D.C.Teixeira, W., Reis, N.J., Bettencourt, J.S., Oliveira, D.C.Intraplate Proterozoic magmatism in the Amazonian craton reviewed: geochronology, crustal tectonics and global barcode matches.Dyke swarms of the world: a modern perspective., 10.1007/978-981-13-1666-1_4 South America, Guiana, Brazilmagmatism

Abstract: We review geochronological data including U-Pb baddelyite ages of Proterozoic mafic dyke swarms and sills of the Amazonian Craton, as well as their geochemical character and geological settings, in order to arrive at an integrated tectonic interpretation. The information together with the characteristics of coeval volcanic-plutonic suites indicates a cyclicity of the mafic-felsic activity through time and space. At least four LIP/SLIP events are apparent, and each one appears to accompany the stepwise accretionary crustal growth of Amazonia. The oldest two, the Orocaima (1.98-1.96 Ga) and Uatumã (c. 1.89-1.87 Ga) SLIPs, comprise calc-alkaline I-type and subordinate A-type plutonic and volcanic rocks. Synchronous mafic intraplate activity occurs across the Guiana and Ce