Updated on 2024/11/22

写真a

 
OTA Tsutomu
 
Organization
Institute for Planetary Materials Chief super technician
Position
Chief super technician
External link

Degree

  • 博士(理学) ( 新潟大学 )

Research Interests

  • geochemistry

  • Petrology

  • 地球化学

  • 岩石学

Research Areas

  • Natural Science / Solid earth sciences

Education

  • Niigata University   自然科学研究科   環境科学

    - 1997

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    Country: Japan

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  • Niigata University    

    - 1997

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  • Ehime University   理学部   地球科学科

    - 1991

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    Country: Japan

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  • Ehime University    

    - 1991

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Papers

  • Unraveling the Cr Isotopes of Ryugu: An Accurate Aqueous Alteration Age and the Least Thermally Processed Solar System Material

    Ryoji Tanaka, Dilan M. Ratnayake, Tsutomu Ota, Noah Miklusicak, Tak Kunihiro, Christian Potiszil, Chie Sakaguchi, Katsura Kobayashi, Hiroshi Kitagawa, Masahiro Yamanaka, Masanao Abe, Akiko Miyazaki, Aiko Nakato, Satoru Nakazawa, Masahiro Nishimura, Tatsuaki Okada, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Yuichi Tsuda, Tomohiro Usui, Sei-ichiro Watanabe, Toru Yada, Kasumi Yogata, Makoto Yoshikawa, Eizo Nakamura

    The Astrophysical Journal   965 ( 1 )   52 - 52   2024.4

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    Publishing type:Research paper (scientific journal)   Publisher:American Astronomical Society  

    Abstract

    The analysis of samples returned from the C-type asteroid Ryugu has drastically advanced our knowledge of the evolution of early solar system materials. However, no consensus has been obtained on the chronological data, which is important for understanding the evolution of the asteroid Ryugu. Here, the aqueous alteration age of Ryugu particles was determined by the Mn–Cr method using bulk samples, yielding an age of 4.13 + 0.62/−0.55 Myr after the formation of Ca–Al-rich inclusions (CAI). The age corresponds to 4563.17 + 0.60/−0.67 Myr ago. The higher 55Mn/52Cr, ε 54Cr, and initial ε 53Cr values of the Ryugu samples relative to any carbonaceous chondrite samples implies that its progenitor body formed from the least thermally processed precursors in the outermost region of the protoplanetary disk. Despite accreting at different distances from the Sun, the hydrous asteroids (Ryugu and the parent bodies of CI, CM, CR, and ungrouped C2 meteorites) underwent aqueous alteration during a period of limited duration (3.8 ± 1.8 Myr after CAI). These ages are identical to the crystallization age of the carbonaceous achondirtes NWA 6704/6693 within the error. The ε 54Cr and initial ε 53Cr values of Ryugu and NWA 6704/6693 are also identical, while they show distinct Δ'17O values. This suggests that the precursors that formed the progenitor bodies of Ryugu and NWA 6703/6693 were formed in close proximity and experienced a similar degree of thermal processing in the protosolar nebula. However, the progenitor body of Ryugu was formed by a higher ice/dust ratio, than NWA6703/6693, in the outer region of the protoplanetary disk.

    DOI: 10.3847/1538-4357/ad276a

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    Other Link: https://iopscience.iop.org/article/10.3847/1538-4357/ad276a/pdf

  • The Formation of a Rubble Pile Asteroid: Insights from the Asteroid Ryugu Reviewed

    Tsutomu Ota, Christian Potiszil, Katsura Kobayashi, Ryoji Tanaka, Hiroshi Kitagawa, Tak Kunihiro, Chie Sakaguchi, Masahiro Yamanaka, Eizo Nakamura

    Universe   2023.6

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    Publishing type:Research paper (scientific journal)  

    DOI: 10.3390/universe9060293

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  • Organic Matter in the Asteroid Ryugu: What We Know So Far Invited Reviewed

    Christian Potiszil, Masahiro Yamanaka, Chie Sakaguchi, Tsutomu Ota, Hiroshi Kitagawa, Tak Kunihiro, Ryoji Tanaka, Katsura Kobayashi, Eizo Nakamura

    Life   2023.6

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    Publishing type:Research paper (scientific journal)  

    DOI: 10.3390/life13071448

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  • Detection of Meteoritic Amino Acids in Extremely Small Sample Sizes: Implications for Sample Return Missions

    Christian Potiszil, Masahiro Yamanaka, Tsutomu Ota, Ryoji Tanaka, Katsura Kobayashi, Eizo Nakamura

    2023.3

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    Publisher:MDPI AG  

    Unmetamorphosed carbonaceous chondrites provide important information concerning the formation and evolution of organic matter, such as amino acids. However, terrestrial contamination remains a valid concern when investigating the organic inventory of meteorites that have fallen to Earth. Accordingly, JAXA’s Hayabusa2 and NASA’s OSIRIS-REx have been launched with the task of returning uncontaminated C-type asteroid material to Earth. The successful Hayabusa2 mission has a very limited sample size (5.4 g). Therefore, many conventional compound specific techniques will struggle to detect amino acids above detection limit with available sample amounts (~several mg to 10’s of mg) being much smaller than those typically used. Here a novel method utilizing ultrahigh performance liquid chromatography-Orbitrap-mass spectrometry is validated and applied to very small meteorite samples, thus providing an approach that can overcome the small sample size constraints of sample return missions. The method is highly sensitive, enabling the detection of amino acids in the carbonaceous chondrites Murchison (2.28 mg) and Orgueil (2.30 mg). Furthermore, quantitation was possible for many of the detected amino acids in Murchison and Orgueil. Using the data presented here, both the amino acid reservoirs of Murchison and Orgueil and the potential application of this method to sample return samples are discussed.

    DOI: 10.20944/preprints202302.0374.v2

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  • Insights into the formation and evolution of extraterrestrial amino acids from the asteroid Ryugu

    Christian Potiszil, Tsutomu Ota, Masahiro Yamanaka, Chie Sakaguchi, Katsura Kobayashi, Ryoji Tanaka, Tak Kunihiro, Hiroshi Kitagawa, Masanao Abe, Akiko Miyazaki, Aiko Nakato, Satoru Nakazawa, Masahiro Nishimura, Tatsuaki Okada, Takanao Saiki, Satoshi Tanaka, Fuyuto Terui, Yuichi Tsuda, Tomohiro Usui, Sei-ichiro Watanabe, Toru Yada, Kasumi Yogata, Makoto Yoshikawa, Eizo Nakamura

    Nature Communications   14 ( 1 )   2023.3

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    Publishing type:Research paper (scientific journal)   Publisher:Springer Science and Business Media LLC  

    Abstract

    All life on Earth contains amino acids and carbonaceous chondrite meteorites have been suggested as their source at the origin of life on Earth. While many meteoritic amino acids are considered indigenous, deciphering the extent of terrestrial contamination remains an issue. The Ryugu asteroid fragments (JAXA Hayabusa2 mission), represent the most uncontaminated primitive extraterrestrial material available. Here, the concentrations of amino acids from two particles from different touchdown sites (TD1 and TD2) are reported. The concentrations show that N,N-dimethylglycine (DMG) is the most abundant amino acid in the TD1 particle, but below detection limit in the other. The TD1 particle mineral components indicate it experienced more aqueous alteration. Furthermore, the relationships between the amino acids and the geochemistry suggest that DMG formed on the Ryugu progenitor body during aqueous alteration. The findings highlight the importance of aqueous chemistry for defining the ultimate concentrations of amino acids in primitive extraterrestrial samples.

    DOI: 10.1038/s41467-023-37107-6

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    Other Link: https://www.nature.com/articles/s41467-023-37107-6

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MISC

  • Supervolcano eruptions driven by melt buoyancy in large silicic magma chambers

    Wim J. Malfait, Rita Seifert, Sylvain Petitgirard, Jean-Philippe Perrillat, Mohamed Mezouar, Tsutomu Ota, Eizo Nakamura, Philippe Lerch, Carmen Sanchez-Valle

    NATURE GEOSCIENCE   7 ( 2 )   122 - 125   2014.2

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    Language:English   Publisher:NATURE PUBLISHING GROUP  

    Super-eruptions that dwarf all historical volcanic episodes in erupted volume(1) and environmental impact(2) are abundant in the geological record. Such eruptions of silica-rich magmas form large calderas. The mechanisms that trigger these super-eruptions are elusive because the processes occurring in conventional volcanic systems cannot simply be scaled up to the much larger magma chambers beneath supervolcanoes. Over-pressurization of the magma reservoir, caused by magma recharge, is a common trigger for smaller eruptions(3), but is insufficient to generate eruptions from large supervolcano magma chambers(4). Magma buoyancy can potentially create sufficient overpressure(4), but the efficiency of this trigger mechanism has not been tested. Here we use synchrotron measurements of X-ray absorption(5) to determine the density of silica-rich magmas at pressures and temperatures of up to 3.6 GPa and 1,950 K, respectively. We combine our results with existing measurements of silica-rich magma density at ambient pressures(6,7) to show that magma buoyancy can generate an overpressure on the roof of a large supervolcano magma chamber that exceeds the critical overpressure of 10-40 MPa required to induce dyke propagation(4), even when the magma is undersaturated in volatiles. We conclude that magma buoyancy alone is a viable mechanism to trigger a super-eruption, although magma recharge and mush rejuvenation(8), volatile saturation(9) or tectonic stress(10) may have been important during specific eruptions.

    DOI: 10.1038/NGEO2042

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  • Supervolcano eruptions driven by melt buoyancy in large silicic magma chambers

    Wim J. Malfait, Rita Seifert, Sylvain Petitgirard, Jean-Philippe Perrillat, Mohamed Mezouar, Tsutomu Ota, Eizo Nakamura, Philippe Lerch, Carmen Sanchez-Valle

    NATURE GEOSCIENCE   7 ( 2 )   122 - 125   2014.2

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    Language:English   Publisher:NATURE PUBLISHING GROUP  

    Super-eruptions that dwarf all historical volcanic episodes in erupted volume(1) and environmental impact(2) are abundant in the geological record. Such eruptions of silica-rich magmas form large calderas. The mechanisms that trigger these super-eruptions are elusive because the processes occurring in conventional volcanic systems cannot simply be scaled up to the much larger magma chambers beneath supervolcanoes. Over-pressurization of the magma reservoir, caused by magma recharge, is a common trigger for smaller eruptions(3), but is insufficient to generate eruptions from large supervolcano magma chambers(4). Magma buoyancy can potentially create sufficient overpressure(4), but the efficiency of this trigger mechanism has not been tested. Here we use synchrotron measurements of X-ray absorption(5) to determine the density of silica-rich magmas at pressures and temperatures of up to 3.6 GPa and 1,950 K, respectively. We combine our results with existing measurements of silica-rich magma density at ambient pressures(6,7) to show that magma buoyancy can generate an overpressure on the roof of a large supervolcano magma chamber that exceeds the critical overpressure of 10-40 MPa required to induce dyke propagation(4), even when the magma is undersaturated in volatiles. We conclude that magma buoyancy alone is a viable mechanism to trigger a super-eruption, although magma recharge and mush rejuvenation(8), volatile saturation(9) or tectonic stress(10) may have been important during specific eruptions.

    DOI: 10.1038/NGEO2042

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  • Space environment of an asteroid preserved on micrograins returned by the Hayabusa spacecraft

    Eizo Nakamura, Akio Makishima, Takuya Moriguti, Katsura Kobayashi, Ryoji Tanaka, Tak Kunihiro, Tatsuki Tsujimori, Chie Sakaguchi, Hiroshi Kitagawa, Tsutomu Ota, Yusuke Yachi, Toru Yada, Masanao Abe, Akio Fujimura, Munetaka Ueno, Toshifumi Mukai, Makoto Yoshikawa, Jun'ichiro Kawaguchi

    PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA   109 ( 11 )   E624 - E629   2012.3

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    Language:English   Publisher:NATL ACAD SCIENCES  

    Records of micrometeorite collisions at down to submicron scales were discovered on dust grains recovered from near-Earth asteroid 25143 (Itokawa). Because the grains were sampled from very near the surface of the asteroid, by the Hayabusa spacecraft, their surfaces reflect the low-gravity space environment influencing the physical nature of the asteroid exterior. The space environment was examined by description of grain surfaces and asteroidal scenes were reconstructed. Chemical and O isotope compositions of five lithic grains, with diameters near 50 mu m, indicate that the uppermost layer of the rubble-pile-textured Itokawa is largely composed of equilibrated LL-ordinary-chondrite-like material with superimposed effects of collisions. The surfaces of the grains are dominated by fractures, and the fracture planes contain not only sub-mu m-sized craters but also a large number of sub-mu m-to several-mu m-sized adhered particles, some of the latter composed of glass. The size distribution and chemical compositions of the adhered particles, together with the occurrences of the sub-mu m-sized craters, suggest formation by hypervelocity collisions of micrometeorites at down to nm scales, a process expected in the physically hostile environment at an asteroid's surface. We describe impact-related phenomena, ranging in scale from 10(-9) to 10(4) meters, demonstrating the central role played by impact processes in the long-term evolution of planetary bodies. Impact appears to be an important process shaping the exteriors of not only large planetary bodies, such as the moon, but also low-gravity bodies such as asteroids.

    DOI: 10.1073/pnas.1116236109

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  • Space environment of an asteroid preserved on micrograins returned by the Hayabusa spacecraft

    Eizo Nakamura, Akio Makishima, Takuya Moriguti, Katsura Kobayashi, Ryoji Tanaka, Tak Kunihiro, Tatsuki Tsujimori, Chie Sakaguchi, Hiroshi Kitagawa, Tsutomu Ota, Yusuke Yachi, Toru Yada, Masanao Abe, Akio Fujimura, Munetaka Ueno, Toshifumi Mukai, Makoto Yoshikawa, Jun'ichiro Kawaguchi

    PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA   109 ( 11 )   E624 - E629   2012.3

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    Language:English   Publisher:NATL ACAD SCIENCES  

    Records of micrometeorite collisions at down to submicron scales were discovered on dust grains recovered from near-Earth asteroid 25143 (Itokawa). Because the grains were sampled from very near the surface of the asteroid, by the Hayabusa spacecraft, their surfaces reflect the low-gravity space environment influencing the physical nature of the asteroid exterior. The space environment was examined by description of grain surfaces and asteroidal scenes were reconstructed. Chemical and O isotope compositions of five lithic grains, with diameters near 50 mu m, indicate that the uppermost layer of the rubble-pile-textured Itokawa is largely composed of equilibrated LL-ordinary-chondrite-like material with superimposed effects of collisions. The surfaces of the grains are dominated by fractures, and the fracture planes contain not only sub-mu m-sized craters but also a large number of sub-mu m-to several-mu m-sized adhered particles, some of the latter composed of glass. The size distribution and chemical compositions of the adhered particles, together with the occurrences of the sub-mu m-sized craters, suggest formation by hypervelocity collisions of micrometeorites at down to nm scales, a process expected in the physically hostile environment at an asteroid's surface. We describe impact-related phenomena, ranging in scale from 10(-9) to 10(4) meters, demonstrating the central role played by impact processes in the long-term evolution of planetary bodies. Impact appears to be an important process shaping the exteriors of not only large planetary bodies, such as the moon, but also low-gravity bodies such as asteroids.

    DOI: 10.1073/pnas.1116236109

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  • In situ ion-microprobe determination of trace element partition coefficients for hornblende, plagioclase, orthopyroxene, and apatite in equilibrium with natural rhyolitic glass, Little Glass Mountain Rhyofite, California

    James G. Brophy, Tsutomu Ota, Tak Kunihro, Tatsuki Tsujimori, Eizo Nakamura

    AMERICAN MINERALOGIST   96 ( 11-12 )   1838 - 1850   2011.11

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    Language:English   Publisher:MINERALOGICAL SOC AMER  

    Partially crystalline hornblende gabbro inclusions from the Little Glass Mountain Rhyolite contain euhedral plagioclase, orthopyroxene, hornblende, and apatite crystals in contact with interstitial rhyolitic (71-76% SiO(2)) glass. Textural and mineral compositional data indicate that the gabbros crystallized sufficiently slowly that surface equilibrium was closely approached at the interface between crystals and the liquid. This rare occurrence represents a natural dynamic crystallization experiment with a "run time" that is not realistically achievable in the laboratory. SIMS analysis of mineral rim-glass pairs have permitted the determination of high-quality, equilibrium trace-element partition coefficients for all four minerals. These data augment the limited partition coefficient database for minerals in high-SiO(2) rhyolitic systems. For all minerals, the D values are consistent with those anticipated from crystal-chemical considerations. These data further support a liquid SiO(2) control on the REEs (and presumably other elements) partitioning wherein D values systematically increase with increasing liquid SiO(2) content.

    DOI: 10.2138/am.2011.3857

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Research Projects

  • Spatiotemporal scale of isotope disequilibria in the mantle, deduced from lithium isotope compositions of mantle peridotite

    Grant number:17K05706  2017.04 - 2020.03

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)  Grant-in-Aid for Scientific Research (C)

    Ota Tsutomu

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    Grant amount:\4420000 ( Direct expense: \3400000 、 Indirect expense:\1020000 )

    The present study focused distributions of hydrogen and fluid-mobile elements including lithium isotopes in orogenic peridotites of the Horoman massif, Japan, to estimate spaciotemporal scales of mantle heterogeneity on light elements. The analytical results on the samples collected at various scales from kilometer (an entire massif) through meter (an outcrop) to submillimeter (a mineral) produced the following outcomes.
    The Horoman peridotites were partly affected at 150 Ma by a subduction-zone fluid. However in the core of the massif, they have retained geochemical characteristics derived from sub-seafloor hydrothermal alteration at 1 Ga. The hydrogen abundances are more than 10-times higher than those of a typical residual mantle. The presence of the Horoman massif suggests that ancient oceanic mantle domains formed by sub-seafloor hydrothermal alteration could have survived in the mantle for at least 1 Gy, and have influenced to dynamics and chemical evolution of the mantle.

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  • An integrated study of Paleoproterozoic high-pressure intermediate-type metamorphic belt: Implication for the operation of modern-style subduction processes

    Grant number:15H05212  2015.04 - 2018.03

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)  Grant-in-Aid for Scientific Research (B)

    Tsujimori Tatsuki

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    Grant amount:\15860000 ( Direct expense: \12200000 、 Indirect expense:\3660000 )

    High-pressure intermediate-type metamorphic belt surrounding the late Archean Tanzania Craton experienced Pacific-type subduction zone metamorphism in Orosirian Period at ca. 2 Ga. Epidote-amphibolite-facies meta-pillow basalts of the belt had a mid-ocean ridge basalt-like affinity. Details of eclogite- and high-pressure granulite-facies metamorphism has also brought new insight into Paleoproterozoic Pacific-type subduction processes.

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  • An integrated study of Paleo- and Neoproterozoic orogenic processes at the Tanzanian craton margin

    Grant number:24403010  2012.04 - 2015.03

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)  Grant-in-Aid for Scientific Research (B)

    TSUJIMORI Tatsuki, OTA Tsutomu, KOBAYASHI Katsura

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    Grant amount:\17160000 ( Direct expense: \13200000 、 Indirect expense:\3960000 )

    High-pressure metamorphic rocks occurring sporadically around the Archean Tanzanian craton record a crustal evolution related to Paleo- and Neoproterozoic orogeny. Our integrated studies confirmed that the Paleoproterozoic subduction-related units including eclogite-bearing high-pressure intermediate-type metamorphic belt and coeval paired granitic batholiths are overprinted significantly by a Pan-African granulite-facies regional metamorphism and deformation. The Pan-African events intrusions played the most important role in the crustal evolution.

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  • Water content and lithium isotope fractionation in subduction-zone mantle olivine

    Grant number:24540513  2012.04 - 2015.03

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)  Grant-in-Aid for Scientific Research (C)

    OTA Tsutomu, MALFAIT WIM J.

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    Grant amount:\5070000 ( Direct expense: \3900000 、 Indirect expense:\1170000 )

    In terms of lithium (Li) isotope fractionation between mantle olivine and aqueous fluid, we examined an interaction between mantle and surficial material, which has strongly affected the earth’s chemical evolution.
    Combining an experimental study in a simple system with Li-isotope analysis of natural mantle olivine revealed that the mantle olivine yielded Li isotopic abundances that fractionated by an interaction with aqueous fluid is relatively enriched in hydrogen, compared with the less fractionated ones.
    This result indicates that mantle materials that interacted with surficial materials have maintained their chemical characteristics including Li isotopic abundance, even under high temperature conditions in mantle on a geologic timescale. The mantle materials, interacted with surficial materials, have been transported back to the mantle by lithospheric plate subduction; such cycling has chemically differentiated the mantle and the surface, that is, the earth’s chemical evolution.

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  • 希ガス同位体を用いた「Old Rock Geochemistry」の展開

    Grant number:21244085  2009 - 2012

    日本学術振興会  科学研究費助成事業 基盤研究(A)  基盤研究(A)

    松本 拓也, 松田 准一, 辻森 樹, 太田 努, 山下 勝行, 宮川 千絵

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    Grant amount:\38220000 ( Direct expense: \29400000 、 Indirect expense:\8820000 )

    本年度は、中国東南部各地から採取したマントル捕獲岩の希ガス同位体分析を完了した。この地域の大陸下lithosphereは比較的最近に大規模な剥奪過程を経験したことが先行研究などにより提唱されており、希ガス同位体がどのような特徴を示すかで、大陸中央部のlithospbereの進化過程に制約条件を与えうると期待できる。分析した試料の特徴としては一様に希ガス含有量がオーストラリアで産出する同様の岩石と比べて少なく、結果として同位体分析もかなり困難であった。ヘリウムの同位体が典型的な上部マントルの億よりも10-20%低い億を示すものもあったため、比較的最近のガスの寄与というよりは、ある程度の期間マントル内で放射集変起源成分の蓄積された領域が存在し、その領域に起因する流体が付加されたものであると推定できる。また、インド洋意の玄武岩試料の分析も完了し中央インド洋海嶺のセグメント毎に明確なヘリウム同位体比の特徴の違いを発見した。一部のセグメントで明確にレユニオンマントルブルームに起因する成分の寄与を発見するとともに.あるセグメントでは上部マントルの値よりも低い3He/4Heが発見され、その様な値は脱ガスを経験した上部マントルがその後少なくとも1000万年以上の期間放射起線のヘリウムを蓄積し、その領域からのガスが特定のセグメントにヘリウムを供給する必要がある。上記2つの研究は対象は異なっているが、いずれも上部マントル内でのローカルな同位体進化を反映した同位体不均一の存在を示唆しており、地球内部の同位体進化を探る上で今後考慮すべき事柄である。また、一部のダイアモンドで見られるネオン同位体の特徴を解釈するために、ネオンの同位体進化曲線をモデル計算し論文として発表した。昨年度来から継続したオーストラリア東部の研究については論文を発表するとともに国際学会にて発表を行った。

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