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Noble gas fractionation during low temperature alteration: an experimental approach.

bullock, M. A.; Schwenzer, S. P.; Bridges, J. C.; Chavez, C.; Filiberto, J.; Kelley, S. P.; Miller, M.; Moore, J. M.; Smith, H.; Swindle, T. D. and Treiman, A. H. (2015). Noble gas fractionation during low temperature alteration: an experimental approach. In: 46th Lunar and Planetary Science Conference, 16-20 Mar 2015, The Woodlands, TX, USA.

URL: http://www.hou.usra.edu/meetings/lpsc2015/pdf/1235...
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Abstract

The heavy noble gases (Ar, Kr, Xe) are key tracers of planetary outgassing, atmospheric formation, and atmospheric evolution. On Mars, at least 3 distinct noble gas signatures have been observed: (1) Noble gas ratios different from the curent Mars atmosphere, but derived from mantle sources, was first found in Chassigny. (2) Shergottites, especially their shock glasses, contain unfractionated Martian atmosphere. (3) The nakhlite Martian meteorites and the ortho-pyroxenite ALH84001 contain fractionated Martian atmosphere that has been explained through several possible mechanisms: (1) The fractionation could represent ancient Martian atmosphere with a noble gas signature different from today. (2) The elementally fractionated noble gases could have entered the rocks via magma, either as a crustal component or via magmatic assimilation of aqueously altered crustal rock. (3) The elementally fractionated noble gases could have entered the rock during the formation of aqueous alteration minerals. Using data from Lafayette ‘iddingsite’, pure pyroxene mineral separate and whole rock samples, we have previously calculated that such an aquously fractionated component could have a 84Kr/132Xe of ~8.

All meteorites that show a fractionated Martian atmospheric component contain alteration products. Carbonates are the main alteration product in ALH 84001, accompanied by magnetite. In the nakhlites several alteration phases have been found; Lafayette contain carbonates, clay (ferric saponite, serpentine), sulfides, and an amorphous component.

Item Type: Conference or Workshop Item
Copyright Holders: 2015 The Authors
Keywords: Mars; alteration; noble gases; fractionation
Academic Unit/School: Faculty of Science, Technology, Engineering and Mathematics (STEM) > Environment, Earth and Ecosystem Sciences
Faculty of Science, Technology, Engineering and Mathematics (STEM)
Learning and Teaching Innovation (LTI) > Institute of Educational Technology (IET)
Learning and Teaching Innovation (LTI)
Research Group: Space
Related URLs:
Item ID: 42493
Depositing User: Susanne Schwenzer
Date Deposited: 15 Apr 2015 09:04
Last Modified: 07 Dec 2018 10:30
URI: http://oro.open.ac.uk/id/eprint/42493
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