Volatile abundances and hydrogen isotope ratios of apatite in martian basaltic breccia NWA 11522 – A paired stone of NWA 7034

Smith, A., Hallis, L. J. , Nagashima, K. and Huss, G. R. (2020) Volatile abundances and hydrogen isotope ratios of apatite in martian basaltic breccia NWA 11522 – A paired stone of NWA 7034. Meteoritics and Planetary Science, 55(12), pp. 2587-2598. (doi: 10.1111/maps.13605)

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Abstract

This study aimed to determine the volatile content (Cl, F, OH) and hydrogen isotope (D/H) ratios of apatite grains within the Martian meteorite NWA 11522, a paired stone of the ungrouped polymict breccia NWA 7034. Apatite F:Cl:OH ratios were measured via SEM‐EDS analyses, and found to be strikingly similar in all grains, and dominated by Cl. Apatite D/H ratios were measured in situ via the Cameca ims 1280 SIMS at the University of Hawai'i. Results varied between δD values of 782 and 52 ‰ and between water contents of 0.127 and 0.510 wt%. The data form a mixing line between two endmembers. The first endmember, a high D/H ratio and low water content endmember, represents a fluid present during the thermal event that lithified the breccia at 1.5 Ga, resetting apatite volatile content, D/H ratio, and U‐Pb ages at this time. The D/H ratio of this fluid suggests that it was derived from the crust/cryosphere (e.g., melted groundwater ice). The second endmember, a low D/H ratio and high water content endmember, represents a second Martian fluid that interacted with the breccia after lithification. The low D/H ratio of this later fluid indicates it was derived from the deeper Martian interior, and may be evidence of an impact‐related hydrothermal system on Mars during the Amazonian period. The presence of these fluids within NWA 11522 suggests that subsurface impact crater environments were still host to liquid water during the past 1.5 Ga on Mars, and still could be to this day.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Smith, Miss Aimee and Hallis, Dr Lydia
Authors: Smith, A., Hallis, L. J., Nagashima, K., and Huss, G. R.
College/School:College of Science and Engineering > School of Geographical and Earth Sciences
Journal Name:Meteoritics and Planetary Science
Publisher:Wiley
ISSN:1086-9379
ISSN (Online):1945-5100
Published Online:22 December 2020
Copyright Holders:Copyright © 2020 The Meteoritical Society (MET)
First Published:First published in Meteoritics and Planetary Science 55(12): 2587-2598
Publisher Policy:Reproduced in accordance with the publisher copyright policy

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