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Ungrouped iron meteorites in Antarctica - Origin of anomalously high abundanceEighty-five percent of the iron meteorites collected outside Antarctica are assigned to 13 compositionally and structurally defined groups; the remaining 15 percent are ungrouped. Of the 31 iron meteorites recovered from Antarctica, 39 percent are ungrouped. This major difference in the two sets is almost certainly not a stochastic variation, a latitudinal effect, or an effect associated with differences in terrestrial ages. It seems to be related to the median mass of Antarctic irons, which is about 1/100 that of non-Antarctic irons. During impacts on asteroids, smaller fragments tend to be ejected into space at higher velocities than larger fragments, and, on average, small meteoroids have undergone more changes in orbital velocity than large ones. As a result, the set of asteroids that contributes small meteoroids to earth-crossing orbits is larger than the set that contributes large meteoroids. Most small iron meteorites may escape from the asteroid belt as a result of impact-induced changes in velocity that reduce their perihelia to values less than the aphelion of Mars.
Document ID
19900060195
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Wasson, John T.
(California, University Los Angeles, United States)
Date Acquired
August 14, 2013
Publication Date
August 24, 1990
Publication Information
Publication: Science
Volume: 249
ISSN: 0036-8075
Subject Category
Lunar And Planetary Exploration
Accession Number
90A47250
Funding Number(s)
CONTRACT_GRANT: NAG9-40
Distribution Limits
Public
Copyright
Other

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