Updated on 2024/12/21

写真a

 
OGASAWARA, Yoshihide
 
Affiliation
Faculty of Education and Integrated Arts and Sciences
Job title
Professor Emeritus
Degree
工学博士 ( 早稲田大学 )
Homepage URL
http://133.9.221.71/

Professional Memberships

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    日本地学教育学会

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    資源地質学会

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    Mineralogical Society of Japan

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    日本岩石鉱物鉱床学会

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    Geological Society of Japan

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    Mineralogical Society of America

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    Geological Society of America (Fellow)

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    American Geophysical Union

▼display all

Research Areas

  • Solid earth sciences

Research Interests

  • Mineralogy, Petrology & Study of Mineral Deposit,Earth material science

 

Papers

  • Grs50PyP50 garnet-bearing composite inclusion in Cr-rich pyrope from Garnet Ridge, the Colorado Plateau

    Suzuki, H, Takebayashi, T, Saito, T, Sakamaki, K, Ogasawara, Y

    JpGU-AGU Joint Meeting 2017 Abstract    2017.05  [Refereed]

  • CaO8 and MgO8 clustering in Grs50Pyp50 garnet in diamond-bearing dolomite marble from the Kokchetav Massif

    Takebayashi, T, Saito, T, Sakamaki, K, Ssuzuki, H, Ogasawara, Y

    JpGU-AGU Joing Meeting 2017 Abstract    2017.05  [Refereed]

  • Discovery of composite lamellae of diopside plus magnetite in discrete olivine crytals from Colorado Plateau diatremes: indication of precursor hydrous ringwoodite

    Sakamaki, K, Sato, Y, Marshall, E.W, Ogasawara, Y

    AGU 2016 Fall Meeting Abstracts   SR33A-2672  2016.12  [Refereed]

  • Discovery of composite lamellae of diopside plus magnetite in discrete olivine crytals from Colorado Plateau diatremes: indication of precurosr hydrous ringwoodite

    Sakamaki, K, Sato, Y, Marshall, E.W, Ogasawara, Y

    Abstracts of AGU 2016 Fall Meeting    2016.12  [Refereed]

  • Significance of pyrope-grossular garnet in diamond-bearing UHP dolomite marble from the Kokchetav massif, Kazakhstan

    Ogasawara, Y, Sakamaki, K, Takebayashi, T, Suzuki, H, Saito, S

    Abstracts of AGU 2016 Fall Meeting    2016.12  [Refereed]

  • Hydrous Na-garnet from Garnet Ridge; products of mantle metasomatism underneath the Colorado Plateau

    Kunihiko Sakamaki, Yuto Sato, Yoshihide Ogasawara

    PROGRESS IN EARTH AND PLANETARY SCIENCE   3  2016.07  [Refereed]  [Invited]

    　View Summary

    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, Mg-x)(2)Si3O12-2x(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 (Si-3.017 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 (Pyp(49-76), 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.

    DOI

  • Diopside and Magnetite Lamellae in Olivine Xenocrysts from the Colorado Plateau: Former Ringwoodite?

    Sakamaki, K. Sato, Y, Marshall, E.W, Ogasawara, Y

    Abstract of Goldschmidt Conference 2016 at Yokohama    2016.06  [Refereed]

  • Intraslab UHP Metasomatism: A Model for the Evolution of Deeply Subducted Carbonates and Calc-silicates and the Formation of Diamond Under H2O Fluid Conditions.

    Ogasawara, Y, Sakamaki, K

    Abstract of Goldschmidt Conference 2016 at Yokohama    2016.06  [Refereed]

  • Disocovery of H2O inclulsions in Kokchetav metamorphic diamond: diamond drystallization during metasomatism in UHP conditions.

    Sakamaki, K, Ogasawara, Y, Schertl, H.P

    Abstract of Japan Geoscience Union Meeting 2016   SMP13-P02  2016.05  [Refereed]

  • Maruyamaite, K(MgAl2)(Al5Mg)Si6O18(BO3)(3)(OH)(3)O, a potassium-dominant tourmaline from the ultrahigh-pressure Kokchetav massif, northern Kazakhstan: Description and crystal structure

    Aaron Lussier, Neil A. Ball, Frank C. Hawthorne, Darrell J. Henry, Rentaro Shimizu, Yoshihide Ogasawara, Tsutomu Ota

    AMERICAN MINERALOGIST   101 ( 1-2 ) 355 - 361  2016.01  [Refereed]

    　View Summary

    Maruyamaite, ideally K(MgAl2)(Al5Mg)Si6O18(BO3)(3)(OH)(3)O, was recently approved as the first K-dominant mineral-species of the tourmaline supergroup. It occurs in ultrahigh-pressure quartzofeldspathic gneisses of the Kumdy-Kol area of the Kokchetav Massif, northern Kazakhstan. Maruyamaite contains inclusions of microdiamonds, and probably crystallized near the peak pressure conditions of UHP metamorphism in the stability field of diamond. Crystals occur as anhedral to euhedral grains up to 2 mm across, embedded in a matrix of anhedral quartz and K-feldspar. Maruyamaite is pale brown to brown with a white to very pale-brown streak and has a vitreous luster. It is brittle and has a Mohs hardness of similar to 7; it is non-fluorescent, has no observable cleavage or parting, and has a calculated density of 3.081 g/cm(3). In plane-polarized transmitted light, it is pleochroic, 0 = darkish brown, E = pale brown. Maruyamaite is uniaxial negative, w = 1.634, e = 1.652, both 0.002. It is rhombohedral, space group R3rii, a = 15.955(1), c = 7.227(1) angstrom, V= 1593(3) angstrom(3), Z= 3. The strongest 10 X-ray diffraction lines in the powder pattern are [d in A(1)(hkl)]: 2.581(100)(051), 2.974(85)(T32), 3.995 (69) (240), 4.237(59)(231), 2.046(54)(762), 3.498(42)(012), 1.923(36)(372), 6.415(23)(T11), 1.595(22) (5.10.0), 5.002(21)(021), and 4.610(20)(030). The crystal structure of maruyamaite was refined to an R, index of 1.58% using 1149 unique reflections measured with MoKa X-radiation. Analysis by a combination of electron microprobe and crystal-structure refinement gave Si02 36.37, A1203 31.50, TiO2 1.09, Cr2O3 0.04, Fe2O3 0.33, FeO 4.01, MgO 9.00, CaO 1.47, Na2O 0.60, K20 2.54, F 0.30, B2O3(calc) 10.58, H2O(calc) 2.96, sum 100.67 wt%. The formula unit, calculated on the basis of 31 anions pfu with B = 3, OH = 3.24 apfu (derived from the crystal structure) and the site populations assigned to reflect the mean interatomic distances, is (K3.53Na0.19Ca0.26H0.02)Dc=1.00(Mg(1.19)Fer(55)FerosTi(0.14) Al(1.0)7)2Y-3.00(Al5.00MgO)(S15.97A10.03018)(BO3)(3)(OH)(3)(OhoFo.160110,24). Maruyamaite, ideally K(MgAl2) (A15Mg)(BO3)3(Si6018)(OH)(3)O, is related to oxy-dravite: ideally Na(MgAl2)(Al5Mg)(BO3)3(S16018) (OH)(3)O, by the substitution xK-: xNa.

    DOI

  • Radiation damage to Kokchetav UHPM diamonds in zircon: Variations in Raman, photoluminescence, and cathodoluminescence spectra

    Rentaro Shimizu, Yoshihide Ogasawara

    LITHOS   206   201 - 213  2014.10  [Refereed]

    　View Summary

    We conducted detailed in-situ Raman, photoluminescence (PL) and cathodoluminescence (CL) studies on microdiamonds in a tourmaline-rich quartzofeldspathic rock from the Kokchetav Massif, Kazakhstan. The microdiamonds occur as inclusions in the cores of K-tourmaline and in zoned zircons with varying U contents. The results of 2D Raman mapping of zircon showed that the U-rich parts were more metamictized than the U-poor parts. All the diamonds showed a strong Raman band at approximately 1332 cm(-1), however, the features of the Raman bands were distinctly different depending on the host minerals. On the one hand, diamonds in tourmaline had a sharp Raman band that is similar to that of kimberlite diamonds [full width at half maximum (FWHM): 2-3 cm(-1)]. On the other hand, diamonds in zircon had a broad and downshifted band compared to those in tourmaline. In particular, diamonds in U-rich cores of zircons (up to 0.15 wt.% UO2) showed broader and more downshifted Raman bands (FWHMs and peak positions varied up to 9.3 cm(-1) and 1328 cm(-1), respectively), with additional small bands at approximately 1490 cm(-1) and 1630 cm(-1). A negative correlation was observed between the peak position and the FWHM of the principal Raman band of microdiamonds. Furthermore, the PL and CL spectra showed systematic variations. Diamonds in zircons with low to moderate U-concentrations had very strong PL and CL compared to diamonds in U-rich zircons and in tourmalines. Several characteristic peaks appeared in the PL and CL spectra, indicating the presence of irradiation and/or nitrogen-related point defects in the diamonds. PL and CL of microdiamonds in high-U zircon were weak, but still showed irradiation-related peaks. The relationship between the occurrence of microdiamonds (i.e., corresponding to the estimated total alpha-dose since crystallization) and the Raman, PL, and CL spectral characteristics of microdiamonds strongly suggests that radiation damage predominantly caused by alpha-particle emission from radioactive decay of actinides (mainly U) in zircon is a principal factor for the spectral variations. Radiation damage (metamictization) is probably a common phenomenon among microdiamonds in zircons in various diamond-bearing rocks from the Kokchetav Massif. To discuss the genesis of diamonds based on their Raman, PL, or CL spectra, it is highly recommended that microdiamonds included in actinide-bearing minerals (e.g., zircon) should be treated with the most careful attention, because post-crystallization radiation damage significantly influences the spectra. (C) 2014 Elsevier BM. All rights reserved.

    DOI

  • Titanite stability in UHP metacarbonate rocks from the Kokchetav Massif, northern Kazakhstan

    Ogasawara, Y

    Gakujutsukenkyu    2014.03  [Refereed]

  • Hydroxyl in clinopyroxene and titanite in a UHP diamond-free garnet-clinopyroxene rock from the Kokchetav Massif, northern Kazakhstan

    Kunihiko Sakamaki, Yoshihide Ogasawara

    INTERNATIONAL GEOLOGY REVIEW   56 ( 2 ) 133 - 149  2014.01  [Refereed]

    　View Summary

    Hydroxyls in clinopyroxene and supersilicic titantite in diamond-free garnet-clinopyroxene rock from the Kumdy-Kol area of the Kokchetav Massif were characterized using micro-FT-IR spectroscopy. The presence of supersilicic titanite is evidence of ultra-high pressure (UHP) metamorphic conditions of at least 6GPa. Significant amounts of hydroxyls were detected suggesting that supersilicic titanite crystallized in an H2O-rich environment at a depth of >200km. Clinopyroxenes coexisting with supersilicic titanite contain exsolved K-feldspar and phengite lamellae and were classified into three types on the basis of exsolved lamellae texture. Hydroxyl was identified in types A and B, but was not present in type C. The variety of reintegrated hydroxyl contents in clinopyroxenes reflected the differences of H2O activities when they crystallized: type C formed at extremely low H2O activities; type B crystallized at high H2O activities; and type A formed under a range of conditions from high (pyroxene cores) to low (pyroxene mantles) H2O activities. Clinopyroxenes recorded local heterogeneity of H2O activity on the scale of individual grains during UHP metamorphism and represent the best indicator of H2O activity. The fluid environment is an important factor attending petrogenesis during UHP metamorphism. Variations in abundance of hydroxyl in UHP clinopyroxene can be used to clarify fluid environments at great depths.

    DOI

  • Water contents of garnets from the Garnet Ridge, northern Arizona: H2O behavior underneath the Colorado Plateau

    Ogasawara, Y, Sakamaki, K. &am, Sato, Y

    2013 AGU Fall Meeting Absracts   V23A-2754  2013.12  [Refereed]

  • OH and H2O of garnets in diamond-bearing and diamond-free garnet-clinopyroxene rocks from the Kumdy-kol area, Kokchetav Massif

    Sakamaki, K. &am, Ogasawara, Y

    2013 AGU Fall Meeting Abstracts   V23A-2755  2013.12  [Refereed]

  • Inclusion/lamella mineralogy and chemical characteristics of garnets from the Garnet Ridge in the Colorado Plateau, northern Arizona

    Sato, Y. &am, Ogasawara, Y

    2013 AGU Fall Meeting Absracts   V23A-2756  2013.12  [Refereed]

  • Radiation damage of the Kokchetav diamonds due to α-particles from zircon – for proper understanding of spectroscopic variations of metamorphic diamonds

    Shimizu, R. &am, Ogasawara, Y

    2013 AGU Fall Meeting Absracts   V23A-2762  2013.12  [Refereed]

  • Strange heterogeneous photoluminescence in the Kokchetav metamorphic diamonds

    Takabe, S. &am, Ogasawara, Y

    2013 AGU Fall Meeting Abstracts   V23A-2763  2013.12  [Refereed]

  • Carbon isotope heterogeneity in metamorphic diamond from the Kokchetav UHP dolomite marble, northern Kazakhstan

    Kyoko Imamura, Yoshihide Ogasawara, Hisayoshi Yurimoto, Minoru Kusakabe

    INTERNATIONAL GEOLOGY REVIEW   55 ( 4 ) 453 - 467  2013.03  [Refereed]

    　View Summary

    We analysed isotopic compositions of metamorphic microdiamond secondary ion mass spectrometry. Typical microdiamonds in this dolomite marble show star-shaped morphologies (S-type) consisting of single-crystal cores and polycrystalline rims. Four S-type microdiamonds and two R-type microdiamonds (single crystals with rugged surfaces) were analysed using a 5m diameter ion beam. S-type microdiamonds have heterogeneous carbon isotopic compositions even in a single grain. Analysis of a typical S-type microdiamond (no. xx01-1-13) revealed clear difference in 13C between core and rim. The rim shows lighter isotopic compositions ranging from17.2 parts per thousand to26.9 parts per thousand, whereas the core is much heavier, with 13C ranging from9.3 parts per thousand to13.0 parts per thousand. The 13C values of R-type microdiamonds fall into narrow ranges from8.3 parts per thousand to14.9 parts per thousand for no. xx01-1-10 and from8.3 parts per thousand to15.3 parts per thousand for no. xx01-1-16. These 13C values are similar to those of the S-type microdiamond cores. The R-type probably formed at the same stage as the core of the S-type, whereas rim growth at a second stage did not occur or occurred very weakly in R-type microdiamonds. These carbon isotopic data support the two-stage growth of microdiamonds in the Kokchetav ultrahigh-pressure host rock. To explain the second stage growth of S-type microdiamonds, we postulate a simple fluid infiltration of light carbon from neighbouring gneisses into the dolomite marble.

    DOI

  • Preface: HP and UHP metamorphic belts in Asia

    Yui, T.F, Ogasawara, Y, Zhan, L.F. &amp, Tsai, C.H

    Journal of Asian Earth Sciences   63, p. 1-4  2013.02  [Refereed]

  • Diversity of potassium-bearing tourmalines in diamondiferous Kokchetav UHP metamorphic rocks: A geochemical recorder from peak to retrograde metamorphic stages

    Rentaro Shimizu, Yoshihide Ogasawara

    JOURNAL OF ASIAN EARTH SCIENCES   63   39 - 55  2013.02  [Refereed]

    　View Summary

    Chemical variations and inclusion mineralogy of tourmaline in diamond-bearing ultrahigh-pressure (UHP) gneisses and related siliceous rocks from the Kokchetav Massif, Kazakhstan are extensively investigated, in conjunction with a review of previously discovered K-bearing tourmaline with microdiamond inclusions. Tourmalines in these Kokchetav UHP rocks have a wide compositional range (dravite - "potassium-oxy-dravite" - schorl - uvite - feruvite - foitite, and some of their oxy-variants) with potassium content ranging from 0 to 0.576 atoms per formula unit (apfu, based on Y + Z + T cations = 15) (or 02.76 wt.% K2O) and decreasing from core to rim. The variation in potassium is spatially related to the inclusion mineralogy and is attributed to changes in metamorphic grade. Four stages of tourmaline growth in the Kokchetav UHP rocks are recognized based on the potassium contents and occurrences; in order of decreasing P and T: (1) K-dominant tourmaline (K > Na, Ca, and X-vacancy) with microdiamond and high-Si-Ti phengite inclusions and without quartz inclusions; (2) K-rich tourmaline (K: 0.2-0.05 apfu) with graphite, phengite, kyanite and quartz inclusions; (3) K-poor tourmaline (K: 0.05-0.01 apfu) with matrix quartz and biotite; and (4) K-free anhedral or overgrown tourmaline associated with low-P-T minerals such as amphibole or chlorite. Several lines of evidence also suggest that K-dominant tourmaline crystallized in the diamond stability field. Tourmalines in the Kokchetav UHP rocks recorded multi-stage growth history from peak UHP conditions through a granulite fades overprint event including partial melting and ultimately to the latest retrograde metamorphism during exhumation. (C) 2012 Elsevier Ltd. All rights reserved.

    DOI

  • Hydroxyl in garnets from Garnet Ridge, northern Arizona

    Ogasawara, Y, Sakamaki, K. &am, Koga, I

    2012 AGU Fall Meeting Abstracts   V43A-2821  2012.12  [Refereed]

  • Coexistence of "wet-" and "dry-clinopyroxenes" in garnet-clinopyroxene rock from the Kokchetav Massif - Evidence for local heterogeneity of H2Oactivity at the depth > 200 km

    Sakamaki, K. &am, Ogasawara, Y

    2012 AGU Fall Meeting Abstracts   V43A-2822  2012.12  [Refereed]

  • Chemical properties of garnet s from Garnet Ridge, Navajo volcanic field in the Colorado Plateau

    Koga, I. &am, Ogasawara, Y

    2012 AGU Fall Meeting Abstracts   V43A-2824  2012.12  [Refereed]

  • "Mysterious bands" in Raman spectra of Kokchetav microdiamonds were photoluminescence - Internal structure of the microdiamond grains by laser excited photoluminescence

    Harada, Y. &am, Ogasawara, Y

    2012 AGU Fall Meeting Abstracts   V51C-07  2012.12  [Refereed]

  • “Fullerene-like” Raman bands in UHP metamorphic diamonds: Metastable intermediate phases for diamond formation

    Harada, Igarashi, Hashiguchi &amp, Ogasawara

    2011 AGU Fall Meeting Abstracts   V23E-2599  2011.12  [Refereed]

  • Chemical characterization of garnets from Garnet Ridge, northern Arizona in the Colorado Plateau

    Koga, I. &am, Ogasawara, Y

    2011 AGU Fall Meeting Abstracts   V23E-2602  2011.12  [Refereed]

  • Hydroxyl distributions in a product of UHP metasomatism: Diamond-free garnet-clinopyroxene rock from the Kokchetav Massif

    Sakamaki, K, Morozumi, H. &am, Ogasawara, Y

    2011 AGU Fall Meeting Abstracts   V23E-2600  2011.12  [Refereed]

  • Possibility of the misidentification of contaminated microdiamonds in UHP metamorphic rocks: An example of diamond grains in Dabie garnet clinopyroxenite

    Ogasawara, Y, Igarashi, M, Tsai, C.H, Iwasaki, I. &amp, Liou, J.G

    2011 AGU Fall Meeting Abstracts   V23E-2609  2011.12  [Refereed]

  • Tale of the Kulet eclogite from the Kokchetav Massive, Kazakhstan: Initial tectonic setting and transition from amphibolite to eclogite

    Zhang, R.Y, Liou, J.G, Omori, S, Sobolev, N.V, Shatsky, S.V, Iizuka, Y., Lo, C.H. &amp, Ogasawara, Y

    Journal of Metamorphic Geology   30, p. 537-559  2011.12  [Refereed]

  • MYSTERIOUS RAMAN BANDS FROM UHP METAMORPHIC MICRODIAMONDS: A RELICT OF INTERMEDIATE PHASE FOR DIAMOND FORMATION

    Ogasawara, Y, Hashiguchi, Y, Igarashi, M. &am, Harada, Y

    GSA Abstracts with Programs   43, p. 47  2011.10  [Refereed]

  • Significance of UHPM carbonates for Deep Carbon Cycle

    Ogasawara, Y

    8th AOGS Annual Meeting Abstracts   S53-A003  2011.08  [Refereed]

  • Fullerene (?) as possible intermediate phase for UHPM diamond formation

    Ogasawara, Y, Igarashi, M. &am, Hashiguchi, Y

    8th AOGS Annual Meeting Abstracts   SE53-A004  2011.08  [Refereed]

  • Significance of K-rich tourmalines in UHP gneisses: geochemical recorder from peak to retrograde metamorphism?

    Shimizu, R. &am, Ogasawara, Y

    8th AOGS Annual Meeting Abstracts   SE53-A022  2011.08  [Refereed]

  • Tale of the Kulet eclogite from the Kokchetav Massif, Kazakhstan: initial tectonic setting and transition from amphibolite to eclogite

    Zhang, R.Y, Liou, J.G, Sobolev, N.V, Shatsky, V.S, Iizuka, Y., Lo, C.H. &amp, Ogasawara, Y

    8th AOGS Annual Meeting Abstracts   SE53-A008  2011.08  [Refereed]

  • The risk of misidentification of contaminated microdiamonds in UHP metamorphic rocks: an example from Dabieshan

    Igarashi, M, Tsai, C.H, Ogasawara, Y. &amp, Liou, J.G

    8th AOGS Annual Meeting Abstracts   SE53-A006  2011.08  [Refereed]

  • Unknown Raman bands in the Kokchetav metamorphic diamonds - intermediate phases, fullerenes (?) for diamond formation

    Igarashi, M, Hashiguchi, Y. &amp, Ogasawara, Y

    8th AOGS Annual Meeting Abstracts   SE53-A005  2011.08  [Refereed]

  • H2O behavior during UHP metamorphism - micro FT-IR study on diamond-free garnet-clinopyroxene rock from the Kokchetav Massif

    Sakamaki, K. &am, Ogasawara, Y

    8th AOGS Annual Meeting Abstracts   SE53-A007  2011.08  [Refereed]

  • Multi-stage growth of microdiamonds in Kokchetav UHP rocks revealed by Raman, photoluminescence and cathodoluminescence spectra

    Shimizu, R. &am, Ogasawara, Y

    8th AOGS Annual Meeting Abstracts   SE53-A016  2011.08  [Refereed]

  • Coesite-exsolution from supersilicic titanite in UHP metasomatic rocks: diamond-free garnet-clinopyroxene rock from the Kokchetav Massif

    Morozumi, H. &am, Ogasawara, Y

    8th AOGS Annual Meeting Abstracts   SE53-A020  2011.08  [Refereed]

  • Eclogite and garnet: a window to the mantle and the subducted oceanic plate underneath the Colorado Plateau

    Koga, I. &am, Ogasawara, Y

    8th AOGS Annual Meeting Abstracts   SE53-A021  2011.08  [Refereed]

  • Evidence for Deep Carbon Cycle: UHPM carbonates, microdiamonds, aqueous fluid and mantle metasomatism

    Ogasawara, Y

    JpGU Meeting 2011 Abstracts   MIS002-01  2011.05  [Refereed]

  • Phlogopite-bearing peridotite from the 25°S oceanic core complex, along the Central Indian Ocean Ridge

    Soda, Y, Igarashi, M, Ogasawara, Y, Takagi, H, Sawaguchi, T, Neo, N, Morishita, T, Nakamura, K. &am, Kumagai, H

    2010 AGU Fall Meeting Abstracts   T23A-2226  2010.12  [Refereed]

  • Chemistry and metamorphic evolution of Kulet eclogite from the Kokchetav Massif, Kazakhstan

    Zhang, R.Y, Liou, J.G, Shatsky, V.S, Ogasawara, Y. &amp, Lo, C

    2010 AGU Fall Meeting Abstracts   V13D-2388  2010.12  [Refereed]

  • Ophiolite

    Liou, J.G, Maruyama, S, Tsujimori, T. &amp, Ogasawara, Y

    McGraw Hill Encyclopedia of Science & Technology   10th Ed.  2010  [Refereed]

  • Petrology of UHP metasomatic rock from the Kumdy-kol area in the Kokchetav Massif

    Iwaoka, H, Shimizu, R, Takeuchi, Y, Ogasawara, Y

    Eos Transactions AGU   87 ( 52 )  2006.12  [Refereed]

  • Microdiamond and graphite in the Kokchetav UHPM dolomite marble - Occurrence and Raman study

    Hashiguchi, Y, Shimizu, R, Ogasawara, Y

    Eos Transactions AGU   87 ( 52 )  2006.12  [Refereed]

  • Petrology of greenstones in southern Wyoming Province

    Takeuchi, Y, Yuasa, T, Ogasawara, Y

    Eos Transactions AGU   87 ( 52 )  2006.12  [Refereed]

  • Tourmaline chemistry in diamond-bearing UHP pelitic gneiss

    Shimizu, R, Ogasawara, Y

    Eos Transactions AGU   87 ( 52 )  2006.12  [Refereed]

  • Mysteries of the Kokchetav UHPM microdiamond

    Ogasawara, Y

    Eos Transactions AGU   87 ( 52 )  2006.12  [Refereed]

  • Microdiamond formation during Intrastab UHP Metasomatism: An example from the Kokchetav Massif

    Ogasawara, Y

    Program & Abstracts of the 19th General Meeting of the IMA     139  2006.07  [Refereed]

  • Occurrence and Characterization of UHPM microdiamonds from the Kokchetav Massif

    Kikuchi, M, Ogasawara, Y

    Program & Abstracts of the 19th General Meeting of the IMA     139  2006.07  [Refereed]

  • Characterization of microdiamonds in “K-tourmaline”-rich UHP rock by Raman spectroscopy

    Shimizu, R, Ogasawara, Y

    Program & Abstracts of the 19th General Meeting of the IMA     140  2006.07  [Refereed]

  • Petrology of Archean greenstone in Wyoming Province-Part 1: Thermal effect of Louis Lake batholigh on Archean greenstones at South Pass, in southern Wind River Range

    Takeuchi, Y, Yuasa, T, Adachi, T, Ogasawara, Y

    EOS Transactions AGU   86  2005.12  [Refereed]

  • Microdiamond formation during "Intraslab UHP Metasomatism"

    Ogasawara, Y

    EOS Transactions AGU   86   F1894  2005.12  [Refereed]

  • Petrology of Archean greenstone in Wyoming Province-Part 2: Significance of skarn formation in Archean greenstone in Wind River Canyon

    Yuasa, T, Takeuchi, Y, Adachi, T, Ogasawara, Y

    EOS Transactions AUG   86   F1894  2005.12  [Refereed]

  • Discovery of `K-tourmaline' in Diamond-Bearing Tourmaline-K-Feldspar-Quartz Rock From the Kokchetav Massif, Kazakhstan

    Shimizu, R, Ogasawara, Y

    EOS Transactions AGU   86   F2006  2005.12  [Refereed]

  • FTIR Study of Microdiamonds From Garnet-Biotite Gneisses of the Kokchetav Massiv, Kazakhstan

    Kikuchi, M, Kagi, H, Ogasawara, Y, Dobrzhinetskaya, L

    EOS Transactions AGU   86   F2004 - F2005  2005.12  [Refereed]

  • Formation of diamond and UHP metasomatism

    Ogasawara, Y

    Liou Symposium at Stanford University    2005.12  [Refereed]

  • The role of fluid for diamond-free UHP dolomitic marble from the Kokchetav Massif

    Y Ogasawara, K Aoki

    INTERNATIONAL GEOLOGY REVIEW   47 ( 11 ) 1178 - 1193  2005.11  [Refereed]

    　View Summary

    A diamond-free, dolomite-bearing UHP marble showing a banded structure occurs at Kumdy-kol in the Kokehetav Massif, northern Kazakhstan. Three centimeter-scale zones occur in this marble (sample no. Y665): zone A = Ti-clinohumite-bearing dolomitic marble; zone B = dolomite marble; and zone C = dolomitic marble lacking Ti-clinohumite and forsterite. The occurrence of phlogopite and garnet lamellae in diopside in zone C suggests UHP metamorphism. Large-area chemical mapping covering about two-thirds of the sample surface was conducted. Ti-K alpha X-ray images clearly indicate that TiO2, is concentrated in zone A. Ca-K alpha and Mg-K alpha images showed that zones A and C have similar modal compositions of carbonates, but they have strong contrasts in TiO2, contents and mineral paragenesis. Mineral assemblages in each zone were analyzed in terms of the CaO-(MgO, FeO)-TiO2-SiO2 compositional tetrahedron. In zone A, the aragonite-Ti-clinohumite tie-line was stable under UHP conditions, whereas it was unstable in zones B and C. This indicates that XCO2 in zone A was lower than that in zones B and C. Infiltration of TiO2-bearing aqueous fluid is implied on the basis of paragenetic relations, distribution of Ti-bearing phases and chemical zonation in Ti-clinohumite in zone A. The lack of microdiamond in this dolomite-bearing carbonate rock suggests extremely low-XCO2, conditions, and implies the infiltration of an aqueous fluid during UHP metamorphism.

  • 超高圧変成作用起源のダイヤモンド-大陸衝突と陸源物質の深部沈み込みの産物

    小笠原義秀

    ニューダイヤモンドフォーラム平成17年度第2回研究会講演要旨集     33 - 39  2005.10  [Refereed]

  • Discovery of K-tourmaline in diamond-bearing quartz-rich rock from the Kokchetav Massif, Kazakhstan

    Shimizu, R, Ogasawara, Y

    Mitteilungen der Osterreichいshcen Mineralogischen Gesellschaft   150   141  2005.08  [Refereed]

  • Characterization of microdiamonds in pelitic gneisses from the Kokchetav Massif, Kazakhstan - Why no 2nd stage growth?

    Ogasawara, Y, Shimizu, R

    Mitteilungen der Osterreichishcen Mineralogischen Gesellschaft   150   121  2005.08  [Refereed]

  • Cathodolumnescence of microdiamond in dolomite marble from the Kokchetav Massif - Another evidence for two-stage growth of diamond

    Yoshioka, N, Ogasawara, Y

    International Geology Review   47 ( 7 ) 703 - 715  2005.07  [Refereed]

  • Microdiamond in pelitic gneisses from the Kokchetav Massif, Kazakhstan

    Ogasawara, Y, Shimizu, R

    Abstracts 2005 of Japan Earth and Planetary Science Joint Meeting     G025 - 007  2005.05  [Refereed]

  • Discovery of K-tourmaline with microdiamond in the Kokchetav UHP rock, Kazakhstan - Implications to boron cycling

    Shimizu, R, Ogasawara, Y

    Abstracts 2005 of Japan Earth and Planetary Science Joint Meeting     G025 - 006  2005.05  [Refereed]

  • Microdiamonds in ultrahigh-pressure metamorphic rocks

    Y Ogasawara

    ELEMENTS   1 ( 2 ) 91 - 96  2005.03  [Refereed]

    　View Summary

    Since the first report of microdiamonds of metamorphic origin in crustal rocks of the Kokchetav Massif, northern Kazakhstan, diamonds have been described from several other ultrahigh-pressure (UHP) metamorphic terranes. In situ diamond is the best indicator of ultrahigh-pressure conditions (> 4 GPa), and testifies to subduction of continental crust to depths within the diamond stability field followed by relatively rapid exhumation In contrast to other UHP terranes, the Kokchetav Massif contains rocks with unusually abundant diamonds, particularly in the Kumdy-Kol region. Kumdy-Kol diamonds exhibit diverse morphologies, dependent upon the host rock. Raman and cathodoluminescence spectra and carbon isotope compositions differ between core and rim, indicating two distinct growth stages.

  • Occurrence of microdiamond in UHP calcite marble from the Kokchetav Massif

    Eos Tranactions AGU   85   F1655  2004.12  [Refereed]

  • Petrology of UHP calcite marble from the Kokchetav Massif

    Eos Transactions AGU   85   F1655  2004.12  [Refereed]

  • Laser Raman study on microdimond in UHP marbles from the Kokchetav Massif

    Eos Transactions AGU   85   F1655  2004.12  [Refereed]

  • Hydroxyl in diopside in diamond-free UHP dolomitic marble from the Kokchetav Massif

    Eos Transactions AGU   85   F1655  2004.12  [Refereed]

  • Intraslab UHP metasomatism - Evidence from the Kokchetav Massif

    Abstracts of 32th International Geological Congress    2004.08  [Refereed]

  • Stability of Ti-bearing assemblages in the Kokchetav UHP marbles

    Abstracts of 32th International Geological Congress    2004.08  [Refereed]

  • Significance of Diamond-free Kokchetav UHP dolomitic marble

    Abstracts of 32th International Geological Congress    2004.08  [Refereed]

  • Diamond-free garnet-clinopyroxene rock from the Kokchetav Massif - As a product of metasomatism under UHP conditions

    Abstracts of 32th International Geological Congress    2004.08  [Refereed]

  • Carbon isotope compositions of microdiamond in UHP marble

    Abstracts of 32th International Geological Congress    2004.08  [Refereed]

  • Two-stage growth of microdiamond in Kokchetav UHP dolomite marble

    Abstracts of 32th International Geological Congress    2004.08  [Refereed]

  • P-T-XCO2 Stabilities of Ti-bearing Phases in Diamond-bearing and Diamond-free UHP Marbles in the Kokchetav Massif

    Abstracts of AOGS 1st Annual Meeting    2004.07  [Refereed]

  • Role of Fluids for the Kokchetav UHP Carbonates

    Abstracts of AOGS 1st Annual Meeting    2004.07  [Refereed]

  • Fluid and bulk composition effect on the phase relations of Ti-bearing assemblages in the Kokchetav UHP marbles

    Abstract of Japan Earth and Planetary Science Joint Meeting    2004.05  [Refereed]

  • Role of the fluid for diamond-free UHP carbonate and calc-silicate rocks from the Kokchetav Massif

    Abstract of Japan Earth and Planetary Science Joint Meeting    2004.05  [Refereed]

  • Discovery of coesite from Indus Suture Zone (ISZ), Ladakh, India: Evidence for deep subduction

    European Journal of Mineralogy   16, 2  2004  [Refereed]

  • Diamond-free UHP garnet-clinopyroxene rock from Kumdy-kol in the Kokchetav Massif

    Eos Transactions AGU   84, F1531  2003.12  [Refereed]

  • Significance of Diamond-free Heterogeneous UHP Dolomitic Marble From the Kokchetav Massif

    Eos Transactions AGU   84, F1532  2003.12  [Refereed]

  • Stability relations of Ti-bearing assemblages in UHP marbles from the Kokchetav Massif

    Eos Tranactions AGU   84, F1532  2003.12  [Refereed]

  • SIMS carbon isotope study of microdiamond in UHP dolomite marble from the Kokchetav Massif

    Eos Transactions AGU   84, F1532  2003.12  [Refereed]

  • Oxygen, carbon,and strontium isotope geochemistry of diamond-bearing carbonate rocks from Kumdy-kol, Kokchetav Massif, Kazakhstan

    Ohta, M, Mock, T, Ogasawara, Y, Rumble, D

    Lithos/Elsevier   70, No.3-4, 77-90  2003.11  [Refereed]

  • Evolution of deeply subducted carbonates and the formation of microdiamond

    Abstracts with Programs/GSA   36, No.6, 137  2003.11  [Refereed]

  • Two stage growth of microdiamonds in UHP dolomite marble from Kokchetav Massif, Kazakhstan

    Ishida, H, Ogasawara, Y, Ohsumi, K, Saito, A

    Journal of Metamorphic Geology/Blackwell   21, 515-522  2003.08  [Refereed]

  • Petrochemical and tectonic processes of UHP/HP terranes II: Preface

    Liou, J.G, Ernst, W.G, Ogaswara, Y

    Journal of Metamorophic Geology/Blackwell Publishing   21, 513-514  2003.08  [Refereed]

  • Carbonate-bearing UHPM rocks from Tso-Morari region, Ladakh, India: petrological implications

    International Geology Review/IUGS   45, 49-69  2003  [Refereed]

  • Petrogenesis of Ti-clinohumite-bearing Garnetiferous Ultramafic Rocks from Kokchetav, Massif

    Eos, Transactions, AGU   83, no.47, F1402  2002.12  [Refereed]

  • Kulet Eclogite from the Kokchetav Massive, Kazakhstan: Transition from Low-grade Amphibolite to Eclogite

    Eos, Transactions, AGU   83, no.47, F1402  2002.12  [Refereed]

  • Morphology and Distribution of Microdiamonds in Dolomite Marble From Kokchetav UHP Massif

    Eos, Transactions, AGU   83, no.47, F1402  2002.12  [Refereed]

  • Cathode luminescence of microdiamond in UHP dolomite marble -New evidence for two stage growth of star-shaped microdiamond

    Eos, Transactions, AGU   83, no.47, F1403  2002.12  [Refereed]

  • Mineral inclusions in zircon from diamond-bearing marble in the Kokchetav massif, northern Kazakhstan

    European Journal of Mineralogy   14, 1103-1108  2002.11  [Refereed]

  • Petrochemical and tectonic processes of UHP/HP terranes I: Preface

    International Geology Review   44, 765-769  2002.09  [Refereed]

  • The mineralogy of the Kokchetav 'lamproite': implications for the magma evolution

    Journal of volcanology and geothermal research   116(35-61  2002.07  [Refereed]

  • The mineralogy of the Kokchetav 'lamproite': implications for the magma evolution

    Journal of Volcanology and geothermal research   116, 35-61  2002.07

  • Coesite exsolution from spuersilicic titanite in UHP marble from the Kokchetav Massif, northern Kazakhstan

    Ogasawara, Y, Fukasawa, K, Maruyama, S

    American Mineralogist/Mineralogical Society of America   87, 454-461  2002.04  [Refereed]

  • Distribution and concentration of microdiamond in UHP dolomite marble

    Eos. Trans. AGU   82, 47  2001.12  [Refereed]

  • Diamond-phengite and diamond-carbonate composite inclusions in UHP dolomite marble from the Kokchetav Massif - Evidence for the formation of microdiamond from fluids

    Abstracts of 6th International Eclogite Conferecne    2001.09  [Refereed]

  • Coesite exsolution from super-silicic titanite - An example of impure UHP marble from the Kokchetav Massif

    Abstract of 6th International Eclogite Conference    2001.09  [Refereed]

  • K2O- and H2O-bearing diopside in UHP calcite marble from the Kokchetav Massif

    Abstracts of 6th International Eclogite Conference    2001.09  [Refereed]

  • New discovery of coesite from the Indian Himalayas

    Abstracts of 6th International Eclogite Conference    2001.09  [Refereed]

  • Petrography of Ti-clinohumite-bearing garnet peridotite from Kumdy-kol area in the Kokhcetav Massif

    Abstract of Japan Earth and Planetary Science Joint Meeting   Rn-P001  2001.06  [Refereed]

  • The estimation of diamond content of diamon-bearing dolomite marble from Kumdy-kol area in the Kokchetav Massif.

    Abstract of Japan Earth and Planetary Science Joint Meeting   Rn-P003  2001.06  [Refereed]

  • Petrology of dolomitic marble and eclogite from the Dabie UHP terrane, eastern China

    Abstract of Japan Earth and Planetary Science Joint Meeting   Rn-P004  2001.06  [Refereed]

  • Coesite inclusions and prograde compositional zonation of garnet in eclogite from Zekou in the Su-Lu ultrahigh-pressure terrane, eastern China

    Journal of Mineralogical and Petrological Sciences   96, 100-108  2001.06  [Refereed]

  • Ceosite exsolution, silica-excess titanite and K2O-, H2O-bearing diopside in calcite marble from the Kokchetav UHPM terrane

    Abstract of the 11th Goldschmidt Conference   #3549  2001.05  [Refereed]

  • Fluid control on metamorphic evolution of deeply subducted carbonates

    Abstarct of the 11th Goldschmidt Conference   #3609  2001.05  [Refereed]

  • Unique high pressure evidence in the Kokchetav UHP carbonate rocks

    Abstract of the 11th Goldschmidt Conference   #3545  2001.05  [Refereed]

  • Permian volcanism in the Mongolian orogenic zone, northeast China: geochemistry, magma sources and petrogenesis

    Geological Magazine   138, 2  2001.04  [Refereed]

  • Ultrapotassic rocks of Boroboye area from Kokchetav UHP terrane, northern Kazakhstan

    EOS, Transactions, AGU   81(48), F1364  2000.12  [Refereed]

  • Coesite exsolution from titanite in UHP marble from the Kokchetav Massif

    EOS, Transactions, AGU   81(48), F1367  2000.12  [Refereed]

  • Very high pressure evidence in calcite marble from Kumdy-kol area in the Kokchetav Massif, northern Kazakhstan

    EOS, Transactions, AGU   81(48), F1367  2000.12  [Refereed]

  • Diamond-phengite composite inclusion in garnet: possible evidence for diamond stability under H2O-bearing fluid in carbonate rock from the Kokchetav Massif

    EOS, Transactions, AGU   81(48), F1364  2000.12  [Refereed]

  • Diamond-bearing and diamond-free metacarbonate rocks from Kumdy-kol in the Kokchetav Massif, northern Kazakhstan

    Ogasawara, Y, Ohta, M, Fukasawa, K, Maruyama, S

    The Island Arc/Blackwell   9, 400-416  2000.09  [Refereed]

  • Petrology of the diamond-grade eclogite in the Kokchetav Massif, northern Kazakhstan

    The Island Arc/Blackwell   9, 379-399  2000.09  [Refereed]

  • Fluid control on the formation and the stability relations of diamond in UHP carbonate rocks from the Kokchetav terrane, northern Kazakhstan

    EOS, Transactions, AGU   81(22), WP241  2000.06  [Refereed]

  • C, O and Sr isotope studies of diamond-bearing marbles from the Kokchetav Massif, northern Kazakhstan

    EOS, Transactions, AGU   81(22), WP241  2000.06  [Refereed]

  • Growth of microdiamond in UHP dolomite marble from Kumdy-kol in the Kokchetav Massif, northern Kazakhstan

    EOS, Transactions, AGU   81(22), WP241  2000.06  [Refereed]

  • Petrology of UHP carbonate rocks from Kumdy-kol in the Kokchetav Massif, northern Kazakhstan

    EOS, Transactions, AGU   81(22), WP248  2000.06  [Refereed]

  • Ultrapotassic magmatism after continental collision in the Kokchetav UHP terrane, northern Kazakhstan

    EOS, Transactions, AGU   81(22), WP248  2000.06  [Refereed]

  • The Permian volcanism in east Inner Mongolia (East China): geochemistry and tectonic significance

    EOS, Transactions, AGU   81(22), WP251  2000.06  [Refereed]

  • Diamond, carbonates and fluids: the stability relations of UHP marbles from the Kokhcetav Massif, northern Kazakhstan

    EOS, Transactions, AGU   81(19), S443  2000.05  [Refereed]

  • Isotopic evidence (C-O-Sr) on the fluid-rock- evolution of diamond-bearing Kokchetav marbles, northern Kazakhstan

    EOS, Transactions, AGU   81(19), S443  2000.05  [Refereed]

  • 直視すべき現状の問題点と学部抜本改革-真の地球市民育成を担う学部を目指して-

    早稲田フォーラム/早稲田大學   79, 52-62  1999.12  [Refereed]

  • Micro Laue X-ray diffraction study on microdiamonds from Kumdy-kol in the Kokchetav UHP Terrane, northern Kazakhstan

    Eos, Transactions, AGU   80 (46), F986  1999.12  [Refereed]

  • Microdiamonds in pelitic gneiss and dolomite marble from Kumdy-kol in the Kokchetav UHP terrane

    Abstracts of 4th International Eclogite Field Sysmposium   17-18  1999.08  [Refereed]

  • Fluid effect to the stability relations of diamond-bearing and diamond-free carbonate rocks from Kumdy-kol in the Kokchetav UHP terrane

    Abstracts of 4th International Eclogite Field Sysmposium   18-19  1999.08  [Refereed]

  • Occurrence of diamond-bearing lamproite from the Kokchetav massif and its significance as the evidence for ultrapotassic magmatism along continental collision zone

    Abstracts of the Annual Meeting of the Geological Society of Japan/Geological Society of Japan    1999.03  [Refereed]

  • Petrology of eclogite and Ti-clinohumite-bearing rock from Kumdy-kol, Kokchetav Massif, Kazakhstan - some mineralogical records of UHP conditions

    Abstracts of the Annual Meeting of the Geological Society of Japan/Geological Society of Japan    1999.03  [Refereed]

  • Petrology and stability relations of diamond-bearing and diamond-free carbonate rocks from Kumdy-kol in the Kokchetav UHP terrane

    Abstracts of the Annual Meeting of the Geological Society of Japan/Geological Society of Japan    1999.03  [Refereed]

  • Morphology and laser Raman study of microdiamonds in pelitic gneiss and dolomite marble from Kumdy-kol, Kokchetav UHP terrane, Kazakhstan

    Abstracts of the Annual Meeting of the Geological Society of Japam/ Geological Society of Japan    1999.03  [Refereed]

  • 14号館教育学部視聴覚教育教室の設計理念とその仕様

    学術研究(教育・社会教育・体育学編)/教育学部   47;9-19  1999.02  [Refereed]

  • Occurrence and stability relations of diamond and carbonates in impure dolomite marble from the Kokchetav Massif, northern Kazakhstan

    Eos, Transactions/American Geophysical Union   79; 46, F983  1998.12  [Refereed]

  • Geology of the Kokchetav UHP-HP unit, northern Kazakhstan

    Eos, Transactions/American Geophysical Union   79; 46, F983  1998.12  [Refereed]

  • Petrology of diamond-bearing impure dolomite marble from the Kokchetav Massif,northern Kazakhstan

    Eos, Transactions/American Geophysical Union   79; 46, F988  1998.12  [Refereed]

  • Petrological study of diamond-grade eclogite in the Kokchetav Massif,northern Kazakhstan

    Eos, Transactions/American Geophysical Union   79; 46, F988  1998.12  [Refereed]

  • New occurrence of clinohypthersthene(?) in garnet bearing ultramafic rock from Donghai in the Su-Lu UHP terrane, eastern China

    Eos, Transactions/American Geophysical Union   79; 46, F990  1998.12  [Refereed]

  • Lamprophyre-granite mingled rock at Virginia Dale, Colorado

    Eos, Transactions/American Geophysical Union   79; 46, F997  1998.12  [Refereed]

  • "UniEQ" a computer program package for constructing petrogenetic grid

    Eos, Transactions/American Geophysical Union   79; 46, F999  1998.12  [Refereed]

  • Clinohypersthene-bearing UHP rock from Donghai in the Su-Lu UHP terrane,eastern China

    Abstracts of International Workshop on UHP Metamorphism and Exhumation/Stanford University   A145-149  1998.12  [Refereed]

  • Ti-clinohumite-bearing garnet rock at Kumdy-kol area in Kokchetav UHP complex: possible evidence of slab-mantle interaction under UHP condition

    Abstracts of International Workshop on UHP Metamorphism and Exhumation/Stanford University   A111-115  1998.12  [Refereed]

  • Petrology of diamond-bearing dolomite marble and diamond-free dolomitic marble from the Kokchetav Massif, northern Kazakhstan

    Abstracts of International Workshop on UHP Metamorphism and Exhumation/Stanford University   A96-100  1998.12  [Refereed]

  • Geology of the eastern Kokchetav metamorphic belt, northern Kazakhstan

    Abstracts of International Workshop on UHP Metamorphism and Exhumation/Stanford University   A86-90  1998.12  [Refereed]

  • Stability relations of microdiamond and carbonates in the marbles from the Kokchetav Massif, northern Kazakhstan

    Abstracts of International Workshop on UHP Metamorphism and Exhumation/Stanford University   A62-65.  1998.12  [Refereed]

  • カザフ共和国北部・コクチェタフ超高圧変成帯の地質と地質構造(1)

    日本地質学会第105年学術大会講演会要旨/日本地質学会   P.217  1998.09  [Refereed]

  • ドロマイトマーブル中のダイアモンドの産状と安定関係

    日本地質学会第105年学術大会講演会要旨/日本地質学会   P.218  1998.09  [Refereed]

  • カザフ共和国コクチェタフ超高圧変成帯産含ダイアモンドドロマイトマーブル

    日本地質学会第105年学術大会講演会要旨/日本地質学会   P.356  1998.09  [Refereed]

  • Interpretation of paragenetic relations and chemical compositions of carbonates from UHP terrane

    Abstract of the 17th International Mineralogical Association   A78  1998.08  [Refereed]

  • Fe-Ti oxides in garnet-bearing ultramafic rock from Donghai in the Su-Lu UHP terrane, eastern China

    Eos, Transactions/American Geophysical Union   79; 46, W126  1998.07  [Refereed]

  • Significance of carbonates in UHP rocks

    Eos, Transactions/American Geophysical Union   79; 46, W128  1998.07  [Refereed]

  • Ti-clinohumite-bearing garnet peridotite from Kumdy-kol area in Kokchetav UHP complex, northern Kazakhstan

    Eos, Transactions/American Geophysical Union   79; 46, W129  1998.07  [Refereed]

  • Petrogenesis of impure dolomitic marble from Dabie Mountains, central China.

    Omori, S, Liou, J.G, Zhang, R.Y, Ogasawara, Y

    The Island Arc/Blackwell   7;1・2  1998.06  [Refereed]

  • Petrogesis of dolomitic marbles from Rongcheng in the Sulu UHP metamorphic terrane, eastern China

    The Island Arc/Blackwell   7;1・2  1998.06  [Refereed]

  • 飛騨変成帯東漆山に産出する変複合貫入岩体

    地質学雑誌/日本地質学会   104;655-671  1998.06  [Refereed]

  • 3D chemical mapping of metamorphic minerals by characteristic X-ray images and back-scattered electron images

    Eos, Transactions/American Geophysical Union   79, S357  1998.05  [Refereed]

  • Serial-grinding and X-ray CT technique for 3D observation of rock textures - an example of magma-mingled rock from Colorado

    Eos, Transactions/American Geophysical Union   79, S356  1998.05  [Refereed]

  • Significance of the Kokchetav Massif in Earth sciences - recent progress in the Kokchetav drilling project

    Abstract of International Symposium on Ignesous and Metarmorphic Rocks/Russian Academy of Sciences    1998.05  [Refereed]

  • 情報教育の現状と展望-地球科学教育における情報化-

    早稲田教育評論/早稲田大学教育総合研究室   第12巻,第1号  1998.03  [Refereed]

  • Garnet lherzolite with olivine-Ti mineral intergrowth from Rongcheng in the Sulu UHP metamorphic terrane, eastern China.

    Eos, Transactions, AGU   Vol.78,F787  1997.12  [Refereed]

  • A preliminary report of nondestructive 3D chemical mapping of textural information.

    Eos, Transactions, AGU   Vol.78,F737  1997.12  [Refereed]

  • 3D observation of magma mingled rock: comparison between serial grinding and X-ray CT methods.

    Eos, Transactions, AGU   Vol.78,F796  1997.12  [Refereed]

  • 3D Chemical mapping of garnet porphyroblasts in an eclogite from the Himalayas.

    Extended Abstracts of Tokyo Workshop on Kokchetav Deep-Drilling Project/Waseda University   100-104  1997.09  [Refereed]

  • What could we learn from deep drilling in an UHP terrane such as the Kokchetav Massif?

    Extended Abstracts of Tokyo Workshop on Kokchetav Deep-Drilling Project/Waseda University   9月16日  1997.09  [Refereed]

  • Phase relations of carbonates during UHP metamorphism. What can we expect in carbonates from the Kokchetav Massif, northern Kazakhstan ?

    Extended Abstracts of Tokyo Workshop on Kokchetav Deep-Drilling Project/Waseda University   44-50  1997.09  [Refereed]

  • Geology of the Kokchetav UHP-HP unit, northern Kazakhstan

    Extended Abstracts of Tokyo Workshop on Kokchetav Deep-Drilling Project/Waseda University   3月8日  1997.09  [Refereed]

  • Model P-T path and the stability relations of carbonates in dolomitic marbles during UHP metamorphism.

    TERRA Nova Abstract/Blackwell   Vol.9, No.1  1997.08  [Refereed]

  • New occurrence of Ti-mineral rod intergrowth in olivine in garnet lherzolite from Rongcheng in the Sulu UHP metamorphism terrane, eastern China.

    TERRA Nova Abstract/Blackwell   Vol.9, No.1  1997.08  [Refereed]

  • 3D chemical mapping of some metamorphic minerals.

    Eos, Transactions, AGU   Vol.78, S327  1997.05  [Refereed]

  • 3D rock textures of magma commingled dike, San Isabel batholith, Wet Mountains, Colorado.

    Eos, Transactions, AGU   Vol.78, S327  1997.05  [Refereed]

  • 地球科学教育に利用できるインターネットWWWサイト.

    地学教育/日本地学教育学会.   第50巻  1997.05  [Refereed]

  • 中国蘇魯超高圧変成帯Rongcheng産ザクロ石レールゾライトからの針状鉱物-カンラン石連晶の発見とその意義

    地球惑星関連学会合同大会予稿集   P.477  1997.03  [Refereed]

  • 地球科学教育におけるインターネット

    早稲田教育評論/早稲田大学教育総合研究室   9;1  1997.03  [Refereed]

  • 3D visualizaton of rock textures

    Ando, K, Omori, S, Ogasawra, Y, Noblett, J

    Proceedings of the 30th International Geological Congress   25   133 - 144  1997  [Refereed]  [Invited]

  • Thermochemical calculation of log f(O(2))-TP stability relations of diamond-bearing assemblages in the model system CaO-MgO-SiO2-C-O-2-H2O

    Y Ogasawara, JG Liou, RY Zhang

    GEOLOGIYA I GEOFIZIKA   38 ( 2 ) 546 - 557  1997  [Refereed]

    　View Summary

    Stability relations of coesite (Co), diopside (Di), diamond (Dm), dolomite (Do), enstatite (En), forsterite (Fo), graphite (Gr), magnesite (Ms) and CO2-bearing fluid at X-CO2 = 0.1 in the model system CaO-MgO-SiO2-C-O-2-H2O were calculated at P = 4 to 8 GPa using available thermodynamic data already published. Isobaric log f(O2)-T stabilities of 4 decarbonation reactions and 4 oxidation reactions together with reaction Dm (Gr) + O-2 = CO2 and diamond-graphite transition were determined. Parageneses of minerals as function of bulk composition were modeled for eclogite, clinopyroxenite, websterite, lherzolite, and carbonate rocks. Reaction Co + Ms = En + Dm + O-2 stabilizes diamond in SiO2-saturated rocks such as eclogite at f(O2) slightly higher than reaction En + Ms = Fo + Dm + O-2 (EMOD). Diamond in SiO2-undersaturated rocks such as lherzolites and websterites, is stable at f(O2) lower than EMOD. Bulk carbon content is also important for the appearance of diamond in silicate rocks. Diopside-rich and carbon-rich compositions are favorable for diamond occurrence in silicate rocks. Ca- and Mg-rich carbonate rocks occur 7 diamond-bearing assemblages at wide f(O2) conditions. Using calculated log f(O2)-T relations, four model PT-f(O2) paths during exhumation and corresponding changes in mineral assemblages were predicted.

  • Significance of Calcite-Dolomite Solvus Geothermometry for UHP Dolomitic Marbles.

    Eos, Transactions, AGU   77;46  1996.12  [Refereed]

  • THERM version 3: An integrated calculation system of mineral equilibria for metamorphic petrology running under PC-UNIX.

    Abstracts of 30th IGC   3  1996.08  [Refereed]

  • 3D visualization of rock textures.

    Ando, T, Omori, S, Ogasawara, Y, Noblett, J

    Abstracts of 30th IGC   3  1996.08  [Refereed]

  • Impure ultra high-P marbles from the Dabie mountains, central China:P-T path and the role of fluids.

    Abstracts of 30th IGC   2  1996.08  [Refereed]

  • Bulk rock compositions and P-T-fO2 stability of diamond-bearing assemblages in the system CaO-MgO-SiO2-C-O2-H2O.

    Abstracts of 30th IGC   2  1996.08  [Refereed]

  • AVSによる岩石組織の3次元観察の試み-マグマ混合した岩石の実例-

    早稲田大学情報科学研究教育センター紀要/早稲田大学情報科学研究教育センター   20  1996.02  [Refereed]

  • Petrogenetic grid for ultrahigh-pressure metamorphism in the model system CaO-MgO-SiO2-CO2-H2O.

    Ogasawara, Y, Liou, J.G, Zhang, R.Y

    The Island Arc/Blackwell Publishing   4;4, 240-253  1995.12  [Refereed]

  • Computer programs of P-T-X relations for metamorphic petrology.

    Eos, Transactions, AGU   76;46  1995.12  [Refereed]

  • 変成岩の内部組織の三次元観察-フランシスカンエクロジャイトへの適用

    1995年度三鉱学会秋季連合講演会要旨    1995.09  [Refereed]

  • CaO-MgO-SiO2-C-O2-H2O系におけるダイアモンドを含む鉱物組み合わせのP-T-logfO2関係の熱化学計算.

    1995年度三鉱学会秋季連合講演会要旨    1995.09  [Refereed]

  • 不純な結晶質石灰岩の中〜超高圧下における相平衡と、その中国大別山産の変成岩への応用

    1995年度三鉱学会秋季連合講演会要旨    1995.09  [Refereed]

  • Stability of diamond-bearing assemblages in the model system CaO-MgO-SiO2-C-O2-H2O.

    Ogasawara, Y, Liou, J.G, Zhang, R.Y

    Chinese Science Bulletin/Chinese Academy of Sciences   40, 105-108  1995.08  [Refereed]

  • Impure marbles from the Xinyan area, Dabie mountains, central China.

    Omori, S, Liou, J.G, Zhang, R.Y, Laili, J.A, Ogasawara, Y

    Chinese Science Bulletin/Chinese Academy of Sciences   40, 98-101  1995.08  [Refereed]

  • Occurrence and stability of diamond-bearing assemblages in ultrahigh-pressure metamorphic rocks.

    Liou. J.G, Ogasawara, Y, Zhang, R.Y

    6th Internat. Kimberlite Conference, Extended Abstract    1995.08  [Refereed]

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Books and Other Publications

  • 超高圧変成作用起源のダイヤモンド(Ultrahigh-Pressure Metamorphic Diamond)-大陸衝突にともなう表層物質深部沈み込みの証拠

    小笠原義秀

    早稲田大学出版部  2009.04 ISBN: 9784657094032

  • 企業年金が危ない!

    李 洪茂, 小笠原 義秀

    講談社  2009.04 ISBN: 9784062725729

  • 地球・環境・資源-地球と人類の共生をめざして

    坂幸恭, 山﨑淳司, 円城寺守, 小笠原義秀, 高木秀雄, 平野弘道, 内田悦生, 大河内博, 香村一夫

    共立出版  2008.09

  • Cathodolulminescence of microdiamond in dolomite marble from the Kokchetav Massif - Additional evidence for two-stage growth of microdiamond

    Yoshioka, N, Ogasawara, Y

    GSA International Book Series  2006.06 ISBN: 0966586999

  • The role of fluid for diamond-free UHP dolomitic marble from the Kokchetav Massif

    Ogasawara, Y, Aoki, K

    GSA International Book Series  2006.06 ISBN: 0966586999

  • Hydroxyl in diopside of diamond-free UHP dolomitic marble from the Kokchetav Massif, Kazakhstan

    Kikuchi, M, Ogasawara, Y

    "Ultrahigh-pressure metamorphism: Deep Continental Subduction", Geological Society of America Special Paper  2006

  • Morphology and distribution of microdiamonds in Dolomite marble from Kumdy-kol

    "The Diamond-Bearing Kokchetav Massif, Kazakhstan"/Universal Academic Press  2002.09 ISBN: 4946443789

  • Coesite exsolution from supersilicic titanite in UHP marble from Kumdy-kol

    "The Diamond-Bearing Kokchetav Massif, Kazakhstan"/Universal Academic Press  2002.09 ISBN: 4946443789

  • Phengite exsolution in diopside in diamond-bearing marble from Kumdy-kol

    "The Diamond-Bearing Kokchetav Massif, Kazakhstan"/Universal Academic Press  2002.09 ISBN: 4946443789

  • Petrology of diamond-bearing dolomite marble from Kumdy-kol

    "The Diamond-Bearing Kokchetav Massif, Kazakhstan"/Universal Academic Press  2002.09 ISBN: 4946443789

  • Petrology of diamond-grade eclogite from Kumdy-kol

    "The Diamond-Bearing Kokchetav Massif, Kazakhstan"/Universal Academic Press  2002.09 ISBN: 4946443789

  • Petrogenesis of Ti-clinohumite-bearing garnetiferous ultramafic rocks from Kumdy-kol

    "The Diamond-Bearing Kokchetav Massif, Kazakhstan"/Universal Academic Press  2002.09 ISBN: 4946443789

  • Petrography and mineral chemistry of Ti-clinohumite-bearing garnet rock from Kokchetav ultrahigh pressure belt

    "Fluid/Slab/Mantle Interactions and Ultrahigh-P Minerals" Department of Earth Sciences, Waseda University  2001.08

  • How deep were carbonates subducted into the mantle? - Unique UHP evidence in the marble from Kokchtava -

    "Fluid/Slab/Mantle Interactions and Ultrahigh-P Minerals" Department of Earth Sciences, Waseda University  2001.08

  • Clinopyroxene phenocryst from the Kokchetav shoshonitic volcanic rocks: implications for multi-stage magma process

    "Fluid/Slab/Mantle Interactions and Ultrahigh-P Minerals" Department of Earth Sciences, Waseda University  2001.08

  • Review of recent rsults from isotope geochemistry in UHPM terranes: Kokchetav, Kazakhstan and Sulu, China

    "Fluid/Slab/Mantle Interactions and Ultrahigh-P Minerals" Department of Earth Sciences, Waseda University  2001.08

  • Geology, petrochemistry and geochronology of the Kokchetav Massif of Kazakhstan: Results of the Tokyo Institute of Technology-Waseda University Kokchetav Research Program, 1997-2001

    "Fluid/Slab/Mantle Interactions and Ultrahigh-P Minerals" Department of Earth Sciences, Waseda University  2001.08

  • Discovery of coesite from Indian Himalaya: Ceonsequences of Himalayan tectonics

    "Fluid/Slab/Mantle Interactions and Ultrahigh-P Minerals" Department of Earth Sciences, Waseda University  2001.08

  • Current advance in the study of ultrahigh-pressure(UHP) metamorphism

    "Fluid/Slab/Mantle Interactions and Ultrahigh-P Minerals" Department of Earth Sciences, Waseda University  2001.08

  • Extremely high diamond concentration in dolomite marble

    "Fluid/Slab/Mantle Interactions and Ultrahigh-P Minerals"/Department of Earth Sciences, Waseda University  2001.08

  • Diamond, fluid and carbonates - Stability and genesis of microdiamond

    "Fluid/Slab/Mantle Interactions and Ultrahigh-P Minerals"/Department of Earth Sciences, Waseda University  2001.08

  • Ophiolite

    McGraw Hill Encyclopedia of Science & Technology  2001

  • Geology, petrology and tectonics of the HP-UHPM Kokchetav Massif, Kazakhstan: Results of the TITech-Waseda Kokchetav research program

    Field Guide Book/4th International Eclogite Field Symposium Committee  1999.08

  • 3D visualization of rock textures.

    Ando T, Omori S, Ogasawara Y, Noblett J

    Proceedings of 30th International Geological Congress/IGC.  1998.03 ISBN: 9067642681

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Research Projects

  • Oxygen isotope study on diamond-facies ultrahigh-pressure metamorphic rocks (Geophysical Lab., Carnegie Inst.)

    Project Year :

    2005
    -
    2007
     

  • Growth mechanism of diamond in deeply subducted materials and its implication for carbon recycling (UC, Riverside; JSPS Long-term Program)

    Project Year :

    2004
    -
    2006
     

  • International Lithosphere Program Task Group: Ultra-Deep Continental Crust Subduction

    Project Year :

    2005
    -
    　
     

  • International Lithosphre Program Task Group III-8 Process and Dynamics in Formation and Exhumation of the Ultrahigh-pressure Metamorphic Terrain

    Project Year :

    1999
    -
    2004
     

  • SIMS carbon isotope study of microdiamonds

    Project Year :

    2002
    -
    2003
     

  • The evolution of deeply subducted carbonates and the formation of microdiamonds

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    2001
    -
    2002
     

    OGASAWARA Yoshihide

    　View Summary

    Deeply subducted carbonate rocks from the Kokchetav Massif, Kazakhstan were investigated in terms of the following subjects.1. Extremely high concentration of microdiamond found in dolomite marble. The contents of microdiamond are largely different domain by domain of the dolomite marble. The highest concentration of diamond were measured as about 2800 carat/ton.2. One of the samples showed the close relations between chemical zonation of garnet and the diamond distribution.3. The microdiamonds in dolomite marbles were classified into three types, S-type, R-type and T-type by their morphology.4. Microscopic observation, micro-Laue diffraction, laser Raman spectroscopy and micro cathode luminescence showed that the microdiamond formed at two stages.5. Micro -aue diffraction clarified the orientation of the rim and the core of S-type microdiamond. The rim is very fine grained transparent crystals and overgrew on the core at the 2^<nd> stage. The core of S-type diamond is a single crystal.6. The results suggested that the microdiamond in dolomite marble formed from fluids during both prograde and retrograde stage of UHP metamorphism

  • New discovery of coesite and ultrahigh-pressure rocks from Indian Himalayas (Wadia Inst. of Himalayan Geology)

    Project Year :

    2001
    　
    　
     

  • Alkali magmatisms at continental collision zones and its significance for Eurasian Plate

    Project Year :

    1999
    -
    2000
     

  • Micro-Laue X-ray diffraction study on the growth mechanism of microdiamonds in dolomite marble in the Kokchetav UHP Terrane (KEK, Japan)

    Project Year :

    1999
    -
    2000
     

  • C, O and Sr isotope compositions of the carbonates in ultrahigh-pressure rocks (Geophysical Lab., Carnegie Inst.)

    Project Year :

    1998
    -
    2000
     

  • Petrogenesis of diamond facies ultrahigh-pressure metamoprphic rocks (Academy of Sciences, Kazakhstan; JSPS Short Term Program)

    Project Year :

    1998
    　
    　
     

  • Ultrahigh-Pressure Metamorphism and Tectonics - Continental Collisions and Meterials Recycling

    Project Year :

    1997
    -
    1998
     

  • International Lithosphre Program Task Group III-6 Ultrahigh-pressure Metamorphism and Geodynamics in Collision Type Orogenic Belts

    Project Year :

    1993
    -
    1998
     

  • Study on ultrahigh-pressre metamorphic terrane, Kazakhstan (TIT)

    Project Year :

    1996
    -
    　
     

  • Study on ultrahigh-pressure carbonate rocks (Stanford University)

    Project Year :

    1993
    -
    　
     

  • Geochemical Studies on Basic Rocks Accompanied with Massive Sulfide Deposits

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research

    Project Year :

    1988
    -
    1990
     

    MARIKO Tadashi, OGASAWARA Yoshihide

    　View Summary

    Geological survey and chemical analyses of main and minor components of Shimokawa basic rocks, Hitachi metamorphic rocks and Sanbagawa metamorphic rocks which contain altered and/or metamorphosed rocks derived from basic volcanic rocks accompanied with massive sulfide deposits were carried out. The results are summarized as follows.1) All Shimokawa basic rocks are considered to be N-type mid-ocean ridge basalt (MORB). They have, however, larger amounts of low ion-potential LIL elements compared with the recent N-type MORB. This is explained by addition of the elements associated with the sea-floor alteration or contamination with pelitic rocks. The similar phenomena are observed in the present day sea-floor basalt from Guaymus basin, Gulf of California.2) Hitachi metamorphic rocks contain schist and gneiss derived from acidic-intermediate-basic volcanic rocks. The geochemical properties suggest that they consist of calc-alkalic, boninitic and back-arc volcanic rocks.3) Most of basic schists in the Sanbagawa metamorphic terrain of Kanto Mountains are N- and T-type MORB. The others are oceanic island tholeiite and alkali basalt.4) Chemical compositions of the rock specimens from Shimokawa, Hitachi and Sanbagawa are considered to have changed sea-floor alteration or regional metamorphism. Among main and minor components of the rocks Na_2O, K_2O, CaO, Sr, Rb are relatively mobile. In contrast, FeO*, MgO, SiO _2, Nb, Ti, Y are immobile. On the basis of the relative and absolute quantity of these immobile elements, tectonic settings of altered and/or metamorphic rocs derived from volcanic rocks in geologic times are estimated

  • The evolution of deeply subducted carbonates and the formation of microdiamonds

    　View Summary

    This study revealed the evidence for the aqueous fluid recycling in the continental materials during deep subduction to form UHP metamorphic rocks and for the metasomatism under UHP conditions. Intraslab UHP metasomatism model was proposed to explain these processes occurred in natural UHP metamorphic rocks. Multicomponent aqueous fluid released from subducted silicate rocks had been infiltrated into carbonate layers and had led to strong metasomatism. During such a metasomatism process, abundant microdiamond could form in carbonate rocks, particularly dolomite marble. Several components could be solved in recycled aqueous fluids under UHP conditions ; TiO2 was one of the representative one. In the Kokchetav UHP metamorphic rocks, Ti-clinohumite occurs in diamond-free UHP dolomitic marble, and the origin of TiO2 in clinohumite could be a solved component in aqueous fluid indicating high H2O activity. This suggest that diamond could be unstable under very high H2O activity even in carbonate rocks and carbon could dissolve into fluid phase. Diopside in this rock contains over 850ppm of H2O as hydroxyl on the basis of micro-FT-IR study. This also means diamond-free dolomitic marble could form under very high H2O activity conditions. Diopside in this marble does not contain K2O-bearing exsolved phases contrary to diamond-bearing dolomite marble. Not only the bulk K2O composition, the solubility of K2O in aqueous fluid under UHP conditions might control the presence of exsolved lamellae in diopside, and probably, K2O had been completely leached out into fluid phase in this rock.K2O-bearing tourmaline had been discovered in tourmaline-K-feldspar-quartz rock, and could be a new mineral because no such high-K2O compositions were reported in tourmaline. The occurrence of this tourmaline also indicates the high activity of volatile components in such rocks and the possibility of aqueous fluid as a carrier for these volatile components.All these results described above strongly suggest the importance of the role of aqueous fluid during UHP metamorphism and lead to the proposed model of“Intraslab UHP metasomatism"

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Internal Special Research Projects

  • 炭酸塩岩の深部沈み込みに伴うダイアモンドの形成と流体の果たす役割

    2002  

    　View Summary

    表層炭酸塩岩が大陸衝突に伴いマントルへ深部沈み込みをした例として、世界で最も深いところまで沈み込み地表に上昇してきたとされているカザフ共和国のコクチェタフ超高圧変成帯のマーブルを用いて標記テーマの研究を行い、以下のような成果を得た。1．ドロマイトマーブル中で多量のマイクロダイヤモンドが生成していること。また、その含有量には試料ごとにきわめて大きな差異があること。ダイヤモンドの最高含有量部分では岩石1トンに換算すると2800カラットとなる。ダイヤモンドを最も多く含有するガーネット粒子の一部に累帯構造を示すものが発見されダイヤモンドの分布との関係が考察された。2．ドロマイトマーブル中のマイクロダイヤモンドは光学顕微鏡下の詳細な形態観察から、R,S,Tの3つのタイプに区分された。これらのマイクロダイヤモンドは2つのステージで成長していることが、放射光を用いたマイクロラウエX線回折、レーザーラマン分光、マイクロカソードルミネッセンスなどの実験データから明らかにされた。3．典型的なマイクロダイヤモンドは“星型”（S-type）をしており、核部と周縁部に区分される。マイクロラウエX線回折により、核部が単結晶であること、また周縁部は透明度の高い半自形結晶で、核部と異なる方位を有することがわかった。またマイクロカソードルミネッセンスのスペクトルとイメージでは明瞭に各部と周縁部の差異が検出された。周縁部で520nm付近のスペクトルが顕著であり、各部はきわめて微弱である。4．以上の結果を総合し、マイクロダイヤモンドは第2ステージで流体から成長した可能性が高いことが示唆された。ドロマイトマーブル中でのダイヤモンドの形成は流体環境（その化学組成と不均質さ）に密接にかかわっていることが決定的になった。5．ダイヤモンドの形成プロセスと深部沈み込み炭酸塩岩とその進化プロセスの一端が解明された。

  • 大陸衝突帯の超高圧変成岩から読み取る地球内部物質循環の情報

    2000  

    　View Summary

    　古生代初期の大陸衝突帯であるカザフ共和国コクチェタフ超高圧変成帯に産出する変成炭酸岩を用いて、大陸起源物質の深部沈み込みとその過程でおこる物質の進化過程およびそこに関わる流体の役割の解明を念頭に、岩石学的・鉱物学的・同位体地球化学的研究を行った。2年間の研究成果として以下のことが明らかになった。１．コクチェタフ超高圧変成帯には、ダイアモンドを含むドロマイトマーブル（a）、ダイアモンドを含まないドロミティックマーブル(b)、コース石の離溶組織をもつチタン石を含む方解石マーブル(c)の、3つの超高圧マーブルが産出する。これらは、表層不純炭酸塩岩の深部沈みこみの産物であり、いずれも同一条件の変成作用を受けている。それぞれが固有の地球深部情報をもっていることがわかった。また、一連の変成岩岩石学的研究からこれらの岩石は圧力数GPaあるいはそれ以上の条件におかれていたことが確実であり、表層物質が深さ200Kmあるいはそれ以上まで沈みこんだことの直接的な証拠である。２．ドロマイトマーブル（a）とドロミティックマーブル（b）の鉱物組み合わせの違いは超高圧変成作用下の流体組成特にXCO2環境の相違で説明される。いずれもH2O-rich環境で安定であるが、（b）は（a）に比べて著しくXCO2が低い条件下で形成されたものであり、また、（b）におけるダイアモンドの欠如もこのことで説明できることがわかった。３．放射光を用いたマイクロラウエ法X線回折とレーザーラマン分光の結果から、ドロマイトマーブル中のマイクロダイアモンドは2つのステージで成長していることが明らかになった。最初のステージでは石墨からの転移でダイアモンドが生成した可能性が高い。またそれを核としてより微小な半自形ダイアモンドが異なった方位で成長している。このダイアモンドは超高圧条件下で変成流体から成長した可能性が濃厚である。４．同位体地球化学的研究から、(b)のドロミティックマーブルは超高圧条件下で外来の流体（特にH2Oに富む）による強い交代作用をこうむっていることが分かった。このことは、超高圧変成作用下においてH2O-rich流体の存在を示唆するだけでなく、沈み込んだ物質が流体成分に対して開放系であることの証拠ともなると解釈できる。

  • 世界の超高圧変成作用とテクトニクス―大陸成長過程・地球深部物質循環過程解明への新たなる挑戦―

    1998   鞠子　正, 高木　秀雄, 安藤　生大, 内田　悦生, J.G.Liou, W.G.Ernst, Cong Bolin, 丸山　茂徳

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    　変成作用とは地球表層物質が地下深所へ運ばれ新たな条件下で安定な岩石に変わる過程である。長い間、変成作用は平均地殻最下部（30数km）までを範囲とする見方が一般的で、圧力は最大１Gpa程度を上限として考えられていた。しかし、1984年のイタリアアルプスの変成岩中からコース石が発見されたのを契機にその圧力スケールは大きく変更されることになった。その後、世界数箇所の同様の岩石からコース石の他、ダイアモンドも発見されるに及び、このような岩石形成過程は超高圧変成作用と呼ばれるようになった。超高圧変成岩の分布は大陸内部に存在する縫合部（かつての大陸が衝突合体した場合）に集中することが明らかにされ、その研究は単に変成岩形成過程にとどまらず、パンゲア分裂以前の大陸の成長過程を明らかにする上で、また地球深部に及ぶ物質循環を考える上でもきわめて重要な役割を果たすことがわかってきた。本研究ではこのような観点から、世界のこの分野の研究者を集めて超高圧変成作用の研究を飛躍的に促進することを目的として計画された。特に、日本の研究者グループは、世界の超高圧変成帯の中でもダイアモンドの産出量の多さや、7Gpaにも達すると見られる非常に高い圧力条件で注目を集めるカザフ共和国コチェタフ超高圧変成帯（５億３千万年前の大陸衝突帯）に焦点を当て、トータル２カ月に及び広域地質調査行い、また約8000個の岩石資料を採取し、引き続く岩石学的研究を展開した。その結果、これまで不明確であったカザフ共和国コチェタフ超高圧変成帯周辺の地質構造のほか、大陸衝突型の超高圧変成帯形成条件とその歴史的側面の詳細が明らかにされてきた。本研究でのおもな活動は下記のとおりである。①1997年６月：日本隊（丸山教授リーダ）による第１回コクチェタフ超高圧変成帯調査。②1997年７月～現在（更に継続中）：変成岩岩石成因論的研究（早大・東工大グループ）。③1997年９月：超高圧変成作用とテクトニクスの国際ワークショップ（早大小笠原主催：詳細はアブストラクト集参照）。④1998年７月：日本隊（東工大・丸山教授リーダ）による第２回コクチェタフ超高圧変成帯調査。⑤1998年12月：超高圧変成作用とテクトニクスの国際ワークショップ（スタンフォード大・Liou教授主催）。⑥1998年12月～1999年２月：カザフ共和国科学アカデミーKasymov教授を早稲田大学に招聘し研究交換（小笠原：学術振興会プログラム）。⑦1999年３月：日本地質学会シンポジウム・コチェタフ超高圧変成帯研究の進展（早大・小笠原主催）。⑧国際誌「The Island Arc」(Blackwell社)にコチェタフ変成帯研究の特集号を企画（2000年の前半に出版予定）。

  • ダイアモンド相超高圧変成岩類における炭酸塩鉱物の安定関係の解明―カザフ共和国コチェタフ地域を例として

    1998  

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    　大陸衝突帯に分布する超高圧変成帯は、大陸成長史の解明に寄与するだけでなく、深さ数百km付近までの地球内部物質循環過程を解明するうえでも、極めて重要な意味をもつ。特に、ダイアモンドを含む超高圧変成岩類は、より深部の情報をもつことからその研究の重要性が指摘されている。世界の数カ所から含ダイアモンド超高圧変成岩の報告があるが、このうちカザフ共和国コチェタフの岩石は、変成炭酸塩岩におけるダイアモンドの共生やダイアモンド含有量の高さ、７Gpa（深さ約200km）にも達する極めて高い圧力を示唆する証拠などから（Okamoto, 19997）などから、最も注目を集める地域である。本研究では、超高圧変成炭酸塩岩が算出するKumdy-kol 地域に焦点を当て、２種の変成炭酸塩岩、ダイアモンドを含むdolomite marble とダイアモンドを含まないdolomitic marble の記載岩石学と両岩石の生成環境の推定を行った。その結果、２種の炭酸塩岩について下記のことが明らか人された。A.ダイアモンドを含むdolomite marble ：①変成ピーク時の鉱物組み合わせ：aragonite + dolomite + garnet + diopside + diamond.②diopside 中に微量のK〈SUB〉2〈/SUB〉O が含まれ、K-feldspar が連晶する。③マイクロダイヤモンドはおもにgarnet 中に含まれ、その他 diopside, phlogopite にわずかに含まれる。④２枚の薄片中に約750粒子のマイクロダイアモンドを見出した。B.ダイアモンドを含まない dolomitic marble：①変成ピーク時の鉱物組み合わせ： aragonite + dolomite +garnet +clinohumite + forsterite + diopside.②Mg-calcite の MgCO〈SUB〉3〈/SUB〉の含有量は最高21.7mol％を得た。これは減圧ステージで aragonite + dolomite から形成されたと解釈される。③garnet が減圧ステージで分解し diopside + spinel に変わっている。C.両炭酸塩岩の安定関係：①鉱物組み合わせの相違とダイアモンドの存在・欠如は両岩石のXCO〈SUB〉2〈/SUB〉の違いで説明可能である。②変成作用ピーク時の想定される圧力・温度条件は、圧力：4.2～7Gpa、温度：980～1250℃の範囲に限定される。

  • 変成岩岩石学のためのインターネットサーバの構築

    1997  

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    急速に普及しているインターネットは、学術雑誌とは質・量共に異なるレベルでの研究成果公開の場として大きな可能性を秘めている。また、その教育現場への活用もさまざまな分野で検討され始まりつつある。研究活動で集積された諸々の情報をデータベース化しインターネット上に公開することは、研究者間の情報交換・議論に資するだけでなく、最新の専門情報を教育現場から容易にアクセスできる環境を提供することにもなり、ひいては一般社会におけるその専門分野の理解をより深めることにつながる。このような専門分野の情報公開は、高度にコンピュータ化しつつある社会における大学の責務といえる。このような観点から、筆者はこれまでの研究で蓄積してきた変成岩岩石学分野の各種データ（P-T図やT-XCO2図などの相平衡図、変成岩の野外露頭データ、顕微鏡写真、岩石・鉱物の化学分析値等）を基に変成岩岩石学を対象とするインターネットサーバを構築することが急務であると考えた。本年度の研究でPC中に構築されたデータベースは以下の通りである。1）変成岩生成の条件推定のための相平衡図の一部、2）現在進行中の変成岩研究データ（主な内容は、カザフ共和国北部のコクチェタフマッシフや中国大別山・蘇魯地域の超高圧変成岩類、米国コロラド州の先カンブリア紀変成岩類・深成岩類、我が国の飛騨変成岩類等の岩石学研究データ）。本年度は予算の関係で本格的なサーバを構築することができなかったため、現有のPCにディスクを増設してその中にデータベースの主要部分を構築した。また、一部のデータについてはHTMLファイルを作成しブラウザからアクセス可能な状態にした。1998年7月導入予定の本格的WWWサーバ(UNIX)に移植し公開するとともに、更にデータの充実を目指す予定である。

  • PC-UNIXを用いた変成岩岩石学のための総合化相平衡関係計算システムの開発

    1996  

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    　変成岩岩石学の分野においては、変成作用の条件解明のために P-T図、TｰX図、T-Xco2図等々の多種多様な相平衡図が活用されている。これらの相平衡図は鉱物の共生関係を基に変成作用についての論議を深めるうえで極めて重要な役割を果たしている。通常、研究者は公表された相平衡図を引用して変成作用の条件推定を行うことが多いが、本来ならば研究者自信が、特別なプログラミングをすることなく、自由に熱力学データを選びながら、自らの手で必要とする相平衡図を得ることが望ましい。このような環境をパーソナルコンピュータ上に実現することを目的として本研究は行われた。　筆者がこれまでにUNIXワークステーションで開発してきたシステムTHERM を背景に、機能を大幅に修正・付加して、PC-UNIX 用システムで稼動するバージョン3を作製した。Solaris2.5 用のバージョンについては、主要部分の開発が終わり、圧力 10GPa までの P-T図・logfo2-T図・T-Xco2図等の計算および X-Window によるグラフィックス表示が可能である。当初予定していた Linux 専用のバージョンは、これまでのTHERM システムの骨格部分・グラフィックス部分に大幅修正が必要なこともあり、メニュー形式インターフェース部分と一部の計算機能のみが利用可能な状態である。他の多く部分は次年度以降に課題を残した。本研究で得られた Solaris2.5 用バージョンを用いて計算された主な結果は以下の通りである。1）上部マントルの超苦鉄質岩・炭酸塩岩中でのダイアモンドの酸化還元安定性（Russian Geololgy & Geophysics，vol.37）、2）ダイアモンドを含む鉱物組み合わせの安定関係とその全炭素含有量依存性（30th IGC at Beijing）、3）超高圧変成帯のドロマイト質マーブルにおける鉱物の安定関係とくに岩石中での Xco2 環境の効果（Eos Transactions，vol.77;The Island Arc，vol.6，in press）。

  • 変成岩岩石学のための統合化相平衡関係計算システムの開発とその活用

    1995  

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    変成岩岩石学の分野で，変成作用の物理化学的条件解明のためにしばしば利用される下記6種の相平衡図の計算と作図をする統合化システムをUNIX上で開発した：（1）P-T図，（2）T-XCO2図，（3）log fO2-T図，（4）T-X1図，（5）P-X1図，（6）組成-共生図。開発のベースにしたシステムは筆者が従来からUNIX上で開発してきた "THERM" であり，その機能を大幅に向上させた新バージョンとなっている。鉱物・流体の熱化学データについては，これまでに公表されている2, 3のinternallyconsistent datasetを引用しデータベース化した。すべての作図はX-Window上で行われるようになっている。また，作図プログラムはX-Window下のXlibライブラリのみで記述されている。 (1)～(3) は純粋鉱物相からなる複合系の相平衡に対して応用できる。反応の安定関係の判定にはSchreinemakersの方法を用いている。計算可能範囲を圧力100 kbar・温度2000℃まで拡大したため，ダイアモンドやコース石が出現することで近年特に注目を集めている超高圧変成作用の相平衡にも応用可能になった。既に超高圧変成作用に応用できるCaO-MgO-SiO2-CO2-H2O系の相平衡は報告した（Ogasawara et al., 1995: The Island Arc, vol.4, no.4）。 (4)～(6) はMg-Fe系やNa-K系などの固溶体を含む複合系の相平衡の計算に利用されるプログラムで，鉱物間のイオンの交換分配平衡のような，2種以上の固溶体鉱物の化学組成と温度・圧力との関係を明らかにする。現在の計算可能範囲は10 kbar・1000℃であるが，近い将来これを拡大し，超高圧変成作用にも活用できるようにする予定である。このプログラムの概要は1995年12月のAGU学会で報告した（Tabei and Ogasawara, 1995）。 本システムの概要は1996年8月の第30回IGC（北京）で報告予定である。

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