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Hydration state of calcium sulfates in Gale crater, Mars: Identification of bassanite veins

In-situ analyses reveal the presence of hydrogen within calcium sulfate veins crosscutting the sediments found in Gale crater. Laboratory experiments were performed to calibrate the hydrogen signal measured by laser induced breakdown spectroscopy (LIBS) in a range applicable to martian data. The ana...

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Bibliographic Details
Published in:Earth and planetary science letters 2016-10, Vol.452 (C), p.197-205
Main Authors: Rapin, W., Meslin, P.-Y., Maurice, S., Vaniman, D., Nachon, M., Mangold, N., Schröder, S., Gasnault, O., Forni, O., Wiens, R.C., Martínez, G.M., Cousin, A., Sautter, V., Lasue, J., Rampe, E.B., Archer, D.
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Language:English
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Summary:In-situ analyses reveal the presence of hydrogen within calcium sulfate veins crosscutting the sediments found in Gale crater. Laboratory experiments were performed to calibrate the hydrogen signal measured by laser induced breakdown spectroscopy (LIBS) in a range applicable to martian data. The analyses indicate that all veins targeted so far at Gale consist predominantly of bassanite which most likely formed by dehydration of gypsum. This scenario suggests that the percolating water produced gypsum, possibly by hydration of anhydrite in aqueous solution, and remained at temperatures below ∼60 °C at that time. Desiccating conditions followed, consistent with a hyperarid climate and favored by burial or impacts. Additionally, anhydrite with lesser bassanite has been found by XRD in samples of sediments hosting the veins. Our result suggests bassanite is likely found in the veins and anhydrite may be more common as a fine-grained component within the sediments. •Experiments on calcium sulfate pellets were performed to calibrate the LIBS hydrogen signal.•Bright veins analyzed in situ at Gale crater are made predominantly of bassanite.•Bassanite could have resulted from the desiccation of gypsum.
ISSN:0012-821X
1385-013X
DOI:10.1016/j.epsl.2016.07.045