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Evidence for differences in the thermal histories of Antarctic and non-Antarctic H chondrites with cosmic-ray exposure ages less than 20 MaAntarctic H chondrites show a different range of induced thermoluminescence properties compared with those of H chondrites that have fallen elsewhere in the world. Recent noble gas data of Schultz et al. (1991) show that this difference is displayed most dramatically by meteorites with cosmic-ray exposure ages less than 20 Ma, and they confirm that the differences cannot be attributed to weathering or to the presence of a great many fragments of an unusual Antarctic meteorite. Annealing experiments on an H5 chondrite, and other measurements on a variety of ordinary chondrites, have shown that induced TL properties are sensitive to the thermal histories of the meteorities. It is concluded that the events(s) that released the less than 20 Ma samples, which are predominantly those with exposure ages of 8 + or - 2 Ma, produced two groups with different thermal histories, one that came to earth several 100,000 years ago and that are currently only found in Antarctica, and one that is currently falling on the earth.
Document ID
19910050072
Document Type
Reprint (Version printed in journal)
Authors
Sears, Derek W. G. (Arkansas Univ. Fayetteville, AR, United States)
Benoit, Paul (Arkansas Univ. Fayetteville, AR, United States)
Batchelor, J. David (Arkansas, University Fayetteville, United States)
Date Acquired
August 15, 2013
Publication Date
April 1, 1991
Publication Information
Publication: Geochimica et Cosmochimica Acta
Volume: 55
ISSN: 0016-7037
Subject Category
LUNAR AND PLANETARY EXPLORATION
Funding Number(s)
CONTRACT_GRANT: NAG9-81
Distribution Limits
Public
Copyright
Other