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An I-Xe Constraint on the Age of the CB Chondrites, and a Reevaluation of the Closure Age of Shallowater Enstatite

Gilmour, Jamie and Crowther, Sarah and Busfield, Alli and Holland, Greg and Whitby, James (2009) An I-Xe Constraint on the Age of the CB Chondrites, and a Reevaluation of the Closure Age of Shallowater Enstatite. Meteoritics and Planetary Science, 44 (4). pp. 573-579. ISSN 1086-9379

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Abstract

The iodine-xenon system has been analyzed in samples of 7 chondrules from the CB chondrites Gujba and Hammadah al Hamra (HaH) 237. One sample from Gujba defined a high temperature iodine-xenon isochron corresponding to closure 1.87 ± 0.4 Ma before closure of Shallowater enstatite. Motivated by this result, we employ outlier rejection to re-evaluate the Shallowater age, leading to a modified value of 4562.3 ± 0.4 Ma (1s̀). In this process, the datum obtained by combining our I-Xe age for Gujba with the literature Pb-Pb age is rejected as an outlier, indicating that in this sample the I-Xe system closed earlier than the accepted Pb-Pb age of chondrules from CB chondrites. The need for a formation environment distinct from that of chondrules from other meteorites is thus reduced.

Item Type: Article
Journal or Publication Title: Meteoritics and Planetary Science
Subjects: G Geography. Anthropology. Recreation > GE Environmental Sciences
Departments: Faculty of Science and Technology > Lancaster Environment Centre
ID Code: 55271
Deposited By: ep_importer_pure
Deposited On: 20 Jun 2012 14:54
Refereed?: Yes
Published?: Published
Last Modified: 09 Apr 2014 23:40
Identification Number:
URI: http://eprints.lancs.ac.uk/id/eprint/55271

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