Opaque Minerals in LL3.0-6 Chondrites I: Mineralogy of Ti-oxides and ~(53)Mn-~(53)Cr Systematics of Ilmenite |
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| Authors: | KIMURA Makoto SUGIURA Naoji NAKAJIMA Haruna Michael K. WEISBERG Faculty of Science Ibaraki University Mito - Japan |
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| Affiliation: | KIMURA Makoto,SUGIURA Naoji,NAKAJIMA Haruna and Michael K. WEISBERG Faculty of Science,Ibaraki University,Mito -,Japan,Department of Earth and Planetary Science,University of Tokyo,Tokyo -,Japan Department of Physical Sciences,Kingsborough College of the City University of New York,Brooklyn,NY Department of Earth and Planetary Sciences,American Museum of Natural History,New York,NY,USA. |
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| Abstract: | ![]()
We conducted a systematic study of oxide minerals in LL3.0-6 chondrites, and found ilmenite, rutile, perovskite and an unknown Al-Ti-Zr-oxide. Ilmenite is low in abundance, but is present in the chondrules and matrix of all the samples that we studied. The MnO content of ilmenite in LL3.0-3.3 is lower than that in LL3.5-6. The low concentration of MnO in the former is due to crystallization from chondrules melts at high temperatures. On the other hand, ilmenite composition in LL3.5-6 reflects thermal metamorphism. Therefore, ilmenite is indicative of petrologic type. We also made the first measurements of the 53Mn-53Cr systematics of ilmenite in ordinary chondrites. The age for ilmenite in Y790256 (LL6) is determined to be about 2 Ma older than angrites. This may represent the metamorphic age of the LL chondrites. |
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| Keywords: | chondrite ilmenite Mn-Cr isotopes |
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