MINERALOGICAL ABSTRACTS FROM SCIENTIFIC PAPERS PUBLISHED IN JAPAN, Edited by the Abstracting Committee, Japan Association of Mineralogical Sciences

摘要

103001 Arai, T., Takeda, H. & Miyamoto, M. Experimental petrology of ancient lunar mare basalt Asuka-881757: Spinel crystallization as a petrologic indicator. Antarctic Meteorite Res., No. 19, 1-19, 5 figs., 10 tables, 2006. The paucity of titanian chromites in lunar-meteorite basalt Asuka (A) 881757 is unusual compared to the general occurrence of coexisting chromites and ulvospinels in the Apollo and Luna mare basalts. The unique spinel crystallization of A 881757 is expected to hold a key to elucidate the crystallization and cooling episodes of the basalt. In this study, we investigated the possible reason for the missing chromite by conducting isothermal and cooling experiments on the bulk-rock composition of A 881757 and discuss the petrogenesis of the ancient low-Ti mare basalt in light of spinel crystallization. A series of isothermal experiments showed the A 881757 basalt magma is not saturated with chromite under the expected lunar oxygen fugacity condition (IWIW-1). A peritectic reaction among chromite, melt, and pyroxene is present for A 881757 basalt magma under the more oxidized condition which is one or two log unit higher than the lunar condition.