Opaque Minerals in LL3.0-6 Chondrites I: Mineralogy of Ti-oxides and ^(53)Mn-^(53)Cr Systematics of Ilmenite

作     者：KIMURA Makoto SUGIURA Naoji NAKAJIMA Haruna Michael K.WEISBERG 

作者机构：Faculty of Science Ibaraki University Mito 310-8512 JapanDepartment of Earth and Planetary Science University of Tokyo Tokyo 113-0033 JapanFaculty of Science Ibaraki University Mito 310-8512 JapanDepartment of Physical Sciences Kingsborough College of the City University of New YorkBrooklyn NY 11235 Department of Earth and Planetary Sciences American Museum of Natural HistoryNew York NY10024 USA. 

出 版 物：《Acta Geologica Sinica(English Edition)》 (地质学报（英文版）)

年 卷 期：2004年第78卷第5期

页      面：1082-1089页

核心收录：

学科分类：07[理学] 070401[理学-天体物理] 0704[理学-天文学] 

主　　题：chondrite ilmenite Mn-Cr isotopes 

摘      要：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.