Terrestrial and Martian weathering signatures of xenon components in shergottite mineral separates |
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| Authors: | J A CARTWRIGHT K D OCKER S A CROWTHER R BURGESS J D GILMOUR |
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| Institution: | 1. School of Earth, Atmospheric and Environmental Sciences, University of Manchester, Williamson Building, Oxford Road, Manchester M13 9PL, UK;2. Present address: Max Planck Institut für Chemie (Otto‐Hahn Institut), Joh.‐Joachim‐Becher‐Weg 27, 55128 Mainz, Germany;3. Institute for Rare Isotope Measurements, University of Tennessee, 10521 Research Drive, Suite 300, Knoxville, Tennessee 37932, USA;4. Present address: Tusculum College, 60 Shiloh Road, Greeneville, Tennessee 37743, USA |
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| Abstract: | Abstract– Xenon‐isotopic ratios, step‐heating release patterns, and gas concentrations of mineral separates from Martian shergottites Roberts Massif (RBT) 04262, Dar al Gani (DaG) 489, Shergotty, and Elephant Moraine (EET) 79001 lithology B are reported. Concentrations of Martian atmospheric xenon are similar in mineral separates from all meteorites, but more weathered samples contain more terrestrial atmospheric xenon. The distributions of xenon from the Martian and terrestrial atmospheres among minerals in any one sample are similar, suggesting similarities in the processes by which they were acquired. However, in opaque and maskelynite fractions, Martian atmospheric xenon is released at higher temperatures than terrestrial atmospheric xenon. It is suggested that both Martian and terrestrial atmospheric xenon were initially introduced by weathering (low temperature alteration processes). However, the Martian component was redistributed by shock, accounting for its current residence in more retentive sites. The presence or absence of detectable 129Xe from the Martian atmosphere in mafic minerals may correspond to the extent of crustal contamination of the rock’s parent melt. Variable contents of excess 129Xe contrast with previously reported consistent concentrations of excess 40Ar, suggesting distinct sources contributed these gases to the parent magma. |
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