P038-10
Tracking Changes in Chemistry of Diagenetic Features in Glen Torridon, Gale Crater, Mars with ChemCam

Thursday, 10 December 2020: 07:27
Virtual
Patrick James Gasda1, Matthew Nellessen2, Debarati Das3, Erwin Dehouck4, Rachel Kronyak5, Deirdra M Fey6, William Rapin7, Pierre-Yves Meslin8, Horton E Newsom9, Megan Hoffman10, Jens Frydenvang11, Roger C Wiens12, Olivier Gasnault7, Samuel M Clegg1 and Sylvestre Maurice13, (1)Los Alamos National Laboratory, Los Alamos, NM, United States, (2)University of New Mexico Main Campus, Albuquerque, NM, United States, (3)McGill University, Montreal, Canada, (4)LGLTPE Laboratoire de Géologie de Lyon : Terre, Planètes et Environnement, Villeurbanne, France, (5)Jet Propulsion Laboratory California Institute of Technology, Pasadena, California, United States, (6)Malin Space Science Systems, San Diego, CA, United States, (7)Universite de Toulouse, Toulouse Cedex 4, France, (8)IRAP, Universite Paul Sabatier, Toulouse, France, (9)Univ New Mexico, Albuquerque, NM, United States, (10)University of New Mexico Main Campus, Earth and Planetary Sciences, Albuquerque, United States, (11)Univ. of Copenhagen, Natural History Museum of Denmark, Copenhagen, Denmark, (12)Space Science and Applications, Los Alamos, NM, United States, (13)Institut de Recherche en Astrophysique et Planétologie (IRAP), Toulouse, France
Abstract:
The NASA Curiosity rover has observed diagenetic features, including concretions, Ca-sulfate fracture fills, and cement throughout the clay-bearing and primarily mudstone Murray formation in Gale crater, Mars. Since sol 2300, Curiosity has been exploring the clay-rich Glen Torridon region and has observed a large diversity of the types of diagenetic features and their chemistry. The timing of the formation of these diagenetic features is important for understanding climate change on Mars, and potentially demonstrated in the transition from Glen Torridon into the overlying layered sulfate unit. Glen Torridon is comprised of four different sections in ascending order: Jura, Knockfarril Hill, fractured Intermediate unit (FIU), and Hutton, the strata just below the basal Siccar Point unconformity (SPU). In Glen Torridon, Ca-sulfate filled fractures are common. Ca-sulfate rich veins, cement, nodules, and light-toned banding are most frequently observed at the base of the FIU, and observed less frequently up to the SPU. FeOT/MgO-rich resistant features were first encountered upon entering the FIU, and tended to increase in MgO and decrease FeOT content up to the SPU. These resistant features do not always differ chemically from the surrounding bedrock. Nearest to the unconformity, MnO/FeO-rich and F/Li/K/MgO-rich fracture fills have been observed on the opposite ends of the MgO-FeOT spectrum observed in the bedrock resistant features. Thus, these fracture fills may be related to, or are endmembers of, resistant features observed in the FIU. The Ca-sulfate features within the FIU may have been altered/replaced by diagenetic processes related to the SPU. Ca-sulfate features are likely a combination of early- and late-stage processes; Ca-sulfate veins appear to cut through other sulfate features. Whether the Ca-sulfate rich features are related to the layered sulfate unit, either as a primary deposit, an early diagenetic consequence of lake drying, or as a late-stage event, will remain uncertain until Curiosity traverses up to the layered sulfate unit. If the sulfate-rich features in Glen Torridon continue to increase in frequency towards the layered sulfate unit, as we might expect on during lake drying, it would point to a relationship between the features and the transition between the units.
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