Institute of Mineralogy, Petrology, and Economic Geology, TohokuUniversity
College of General Education, Tohoku University
Instituteof Mineralogy, Petrology, and Economic Geology, Tohoku University
抄録(英)
Rubidium and strontium abundances as well as Sr isotopic compositions were analyzed for the impact-melted meteorites (LL-chondrite : Yamato-790723 and -790528) from Antarctica to clarify their Rb-Sr features and to date the impact events. The samples were separated according to the magnetic property. The less magnetic and glass-rich portions of Y-790723 approximate an isochron of 1.27±0.19 Ga. The obtained age should indicate the impact event. The magnetic portions and fine-grained one largely deviate from the isochron. Y-790528 is rather depleted in K_2O and Rb, but not in Na_2O; this may be due to scarcity of the K-rich fragments. The ^<87>Sr/^<86>Sr ratios of the separated portions from Y-790528 are low and less variable. The five less magnetic portions of the Y-790528 chondrite seem to form the isochron of 4.36±0.76Ga as the time of the impact event. The large errors may have derived from local reset of the Rb-Sr chronometer and incomplete separation into the portions.
雑誌書誌ID
AA10784627
雑誌名
Proceedings of the NIPR Symposium on Antarctic Meteorites
Rb-Sr features of the impact-melted LL-chondrites from Antarctica:Yamato-790723 and Yamato-790528
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KJ00000036391
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概要
