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a recent meteorite shower in antarctica with an unusual orbital historyThe Antarctic meteorite collection has proved to be a source of many important discoveries, including a number of previously unknown or very rare meteorite types. A thermoluminescence (TL) survey of meteorite samples recovered by the 1988/89 European expedition and pre-1988 American expeditions to the Allan Hills Main blue ice field resulted in the discovery of 15 meteorites with very high TL levels (greater than 100 krad at 250 C in the glow curve). It is likely that these samples are fragments of a single meteoroid body which: (1) fell very recently and (2) experienced a decrease in orbital perihelia from greater than or equal to 1.1 AU to 1 AU within the last 10(exp 5) yr. Carbon-14 data for two of the samples confirm their young terrestrial age compared to most Antarctic meteorites. Studies of the cosmogenic isotopes in at least one non-Antarctic meteorite which also has very high natural TL, Jilin, indicate that the meteorite experienced a multi-stage irradiation history, the most recent stage being 0.4 Ma in duration following a major break-up of the object. These meteorites, and the few equivalent modern falls, are the only documented samples from bodies which were recently in Earth-approaching (Amor) orbits (i.e., with perihelion greater than 1.0 AU), as opposed to the Earth-crossing (Apollo) orbits which are the source of most other meteorites. Their rarity indicates that such rapid orbit changes are unusual for meteoroid bodies and may be the result of isolated, large break-up events.
Document ID
19950042387
Document Type
Reprint (Version printed in journal)
Authors
Benoit, P. H.
(University of Arkansas, Fayetteville, AR United States)
Sears, D. W. G.
(University of Arkansas, Fayetteville, AR United States)
Date Acquired
August 16, 2013
Publication Date
December 1, 1993
Publication Information
Publication: Earth and Planetary Science Letters
Volume: 120
Issue: 4-Mar
ISSN: 0012-821X
Subject Category
LUNAR AND PLANETARY EXPLORATION
Funding Number(s)
CONTRACT_GRANT: NAG9-81
CONTRACT_GRANT: NSF DPP-91-15521
Distribution Limits
Public
Copyright
Other