| Project/Area Number |
63400003
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| Research Category |
Grant-in-Aid for General Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
広領域
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| Research Institution | University of Tokyo |
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Principal Investigator |
TAKEDA Hiroshi Univ. of Tokyo, Mineralogical Inst., Prof., 理学部, 教授 (50011523)
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| Co-Investigator(Kenkyū-buntansha) |
SUGIURA Naoji Univ. of Tokyo, Dept. of Geophys., Assoc. Prof., 理学部, 助教授 (80196716)
MORI Hiroshi Univ. of Tokyo, Mineralogical Res. Assoc., 理学部, 助手 (30174379)
MIYAMOTO Masamichi Univ. of Tokyo, College of Arts and Sci., Lecturer, 教養学部, 講師 (70107944)
TOMEOKA Kazushige Univ. of Tokyo, Mineralogical Res. Assoc., 理学部, 助手 (00201658)
TAGAI Tokuhei Univ. of Tokyo, Mineralogical Assoc. Prof., 理学部, 助教授 (40011738)
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| Project Period (FY) |
1988 – 1989
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| Keywords | Achondrites / Antarctic Meteorites / Crystal fractionation / Shock metamorphism / Material evolution / Chemical map analysis / Meteorite parent body / Differentiated meteorites |
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| Research Abstract |
Comparative and comprehensive studies of several Antarctic meteorites of the achondrite group have been carried out to reconstruct their parent bodies and to deduce their formation processes. The parent bodies of achondrites have been thought of protoplanets with differentiated crusts and mantles produced by melting and crystal fractionation from the primitive materials in the early solar system, and will provide us with useful information to deduce early evolution of moon and terrestrial planets.
This year, we investigated several Antarctic achondrites, which have been characterized last year. The samples include ureilites resembling terrestrial ultramafic mantle rocks, and eucrites having basaltic composition. The textures, mineral assemblages, and variations of chemical compositions within their minerals have been analyzed by two-dimensional chemical mapping analysis techniques of the scanning electron microscope (SEM) with an Energy Dispersive Solid State Detector (EDS), which has been installed by this grant this year.
We found that chemical variations recorded in a few heavily shocked ureilites give us information on how some elements were removed from carbonaceous chondrite-like source materials when the parent body was produced. One Yamato ureilite preserved thick carbonaceous veins, which might have been a drain channel of these elements including Al,Ca, Fe and S.
One encritic breccia has been found to include mineral and lithic fragments, which had been formed close together in the crust and mantle of their parent body. This study supports an idea that their crust was formed in sequence by crystal fractionation. Many of encritic meteorites experienced a thermal metamorphism induced by shock events. Lunar meteorites include also rock fragments produced by a large basin forming cratering event.
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