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Simulating evaporative wet and dry cycles in Gale crater, Mars using thermochemical modeling techniques.
  • +7
  • Debarati Das,
  • Stuart Matthew Robert Turner,
  • Susanne P Schwenzer,
  • Patrick J Gasda,
  • Jim Palandri,
  • Kim Berlo,
  • Richard John Leveille,
  • Laura J Crossey,
  • Benjamin M. Tutolo,
  • Nina L. Lanza
Debarati Das
Los Alamos National Laboratory

Corresponding Author:[email protected]

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Stuart Matthew Robert Turner
The Open University
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Susanne P Schwenzer
Open University
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Patrick J Gasda
Los Alamos National Laboratory (DOE)
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Jim Palandri
University of Oregon
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Kim Berlo
McGill University
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Richard John Leveille
McGill University
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Laura J Crossey
University of New Mexico
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Benjamin M. Tutolo
University of Calgary
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Nina L. Lanza
Los Alamos National Laboratory (DOE)
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Abstract

The aim of this work is to understand the formation of primary evaporites—sulfates, borates, and chlorides—in Gale crater using thermochemical modeling to determine constraints on their formation. We test the hypothesis that primary evaporites required multiple wet-dry cycles to form, akin to how evaporite assemblages form on Earth. Starting with a basalt-equilibrated Mars fluid, Mars-relevant concentrations of B and Li were added, and then equilibrated with Gale lacustrine bedrock. We simulated cycles of evaporation followed by groundwater recharge/dilution to establish an approximate minimum number of wet-dry cycles required to form primary evaporites. We determine that a minimum of 250 wet-dry cycles may be required to start forming primary evaporites that consist of borates and Ca-sulfates. We estimate that ~14,250 annual cycles (~25.6 k Earth years) of wet and dry periods may form primary borates and Ca-sulfates in Gale crater. These primary evaporites could have been remobilized during secondary diagenesis to form the veins that the Curiosity rover observes in Gale crater. No LiCl salts form after 14,250 cycles modeled for the Gale-relevant scenario (approximately 106 cycles would be needed) which implies Li may be leftover in a groundwater brine after the time of the lake. No major deposits of borates are observed to date in Gale crater which also implies that B may be leftover in the subsequent groundwater brine that formed after evaporites were remobilized into Ca-sulfate veins.
24 May 2023Submitted to ESS Open Archive
25 May 2023Published in ESS Open Archive