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Degree of equilibration of eucritic pyroxenes and thermal metamorphism of the earliest planetary crust
Author(s) -
Takeda Hiroshi,
Graham A. L.
Publication year - 1991
Publication title -
meteoritics
Language(s) - English
Resource type - Journals
eISSN - 1945-5100
pISSN - 0026-1114
DOI - 10.1111/j.1945-5100.1991.tb01028.x
Subject(s) - metamorphism , geology , meteorite , parent body , crust , petrography , geochemistry , astrobiology , chondrite , physics
— The pyroxenes in two new monomict eucrites from Antarctica, Yamato 791186 and Yamato 792510, have been studied and compared with those of other Antarctic and non‐Antarctic eucrites. The purpose of this study is to identify compositional and textural relationships shown by these pyroxenes which may be used as indicators of the thermal history of the meteorite. An attempt is made, using petrographic and compositional criteria, to distinguish between the initial cooling history and subsequent thermal events. We suggest that it is possible to identify stages of thermal “metamorphism” which may be used to indicate the conditions on the surface and crust of the parent body. A picture of the geological setting of the HED (Howardites, Eucrites, Diogenites) parent body is proposed, for which thermal metamorphism by impact heating is an important process.