40Ar-39Ar analyses of a lumar meteorite (Yamato-86032) and a few LL3 and LL4 chondrites from Antarctica

^<40>Ar-^<39>Ar analyses were performed for a lunar meteorite (Yamato-86032), two LL3 (Y-790448,Allan Hills-764) and one LL4 (Y-74442) chondrites from Antarctica. The lunar meteorite Y-86032 shows a scattered ^<40>Ar-^<39>Ar age spectrum with anomalously high ages in the high...

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Bibliographic Details
Main Authors: Kaneoka,Ichiro, Nagao,Keisuke
Format: Report
Language:English
Published: Earthquake Research Institute, University of Tokyo/Institute for Study of Earth's Interior, Okayama University 1993
Subjects:
Online Access:https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=4603
http://id.nii.ac.jp/1291/00004603/
https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=4603&item_no=1&attribute_id=18&file_no=1
Description
Summary:^<40>Ar-^<39>Ar analyses were performed for a lunar meteorite (Yamato-86032), two LL3 (Y-790448,Allan Hills-764) and one LL4 (Y-74442) chondrites from Antarctica. The lunar meteorite Y-86032 shows a scattered ^<40>Ar-^<39>Ar age spectrum with anomalously high ages in the higher temperature fractions, indicating a shock effect on the analyzed sample. Among the three LL chondrites analyzed, the sample Y-790448 indicates a plateau ^<40>Ar-^<39>Ar age of 4521±28Ma in the lower temperature fractions (600-800℃). The other two LL chondrites show inverse staircase spectra in the higher temperature fractions. In the LL chondrite group, un-equilibrated chondrites seem to show older ^<40>Ar-^<39>Ar ages compared with equilibrated ones, which may be related to the differences in the thermal history of each portion of their parent body.