P070-07
Geochemical Processes Along and Above the Glen Torridon/Greenheugh Pediment, Unconformity, Gale Crater, Mars: Results from the Sample Analysis at Mars Instrument.

Tuesday, 15 December 2020: 05:48
Virtual
Brad Sutter1, Amy McAdam2, Doug Archer Jr.1, Douglas W Ming3, Jennifer L Eigenbrode4, Elizabeth B Rampe3, Joanna Victoria Hogancamp1, Tanya Peretyazhko1, Daniel Patrick Glavin5, Albert Yen6, Rafael Navarro-Gonzalez7, Charles Malespin4 and Paul R Mahaffy2, (1)Jacobs Technology, NASA Johnson Space Center, Houston, TX, United States, (2)NASA Goddard SFC, Greenbelt, MD, United States, (3)NASA Johnson Space Center, Houston, TX, United States, (4)NASA Goddard Space Flight Center, Greenbelt, MD, United States, (5)NASA Goddard Space Flight Center, Solar System Exploration Division, Greenbelt, MD, United States, (6)NASA Jet Propulsion Laboratory, Pasadena, CA, United States, (7)Universidad Nacional Autonoma de Mexico, Mexico City, EM, Mexico
Recorded Presentation
Abstract:
The Sample Analysis at Mars (SAM) instrument on board the Curiosity rover has analyzed samples from the Glen Torridon (GT) smectite-bearing unit and the unconformably overlying Greenheugh Pediment (GP) in Gale Crater. The objectives were to evaluate SAM-Evolved Gas Analysis (EGA) volatiles to 1). Determine if mineralogical/chemical linkages exist between the GP Edinburgh (EB) sandstone target and the underlying GT Hutton (HU) sample and 2). Determine if the GT Glasgow (GG) and stratigraphically higher (+13m) HU materials encountered alteration related to the unconformity. The SAM-EGA detected differences in evolved H2O, SO2, CO2, O2, and NO suggesting differing source material and/or depositional/alteration processes between EB and HU. Evolved H2O in HU consisted of 2 water peaks (adsorbed water, hydrated salts, Fe-hydroxides) that were also present in EB that had an additional 2 water peaks consistent with phyllosilicates. SO2 detections indicated that EB contained Fe-sulfate/sulfides and some Mg-SO4 while HU contained only Fe-sulfates. Nitrate and perchlorate detection in EB but not HU and other GT materials indicated that EB depositional fluids were enriched in nitrate and perchlorate but absent in GT. EB (1400±1000 μgC/g) and HU (1200±1000 μgC/g) evolved similar CO2 amounts that spanned similar temperature ranges consistent with contributions from oxidized organic carbon. Subsequent to the unconformity formation, HU may have experienced multiple alteration events that could explain the SAM-EGA differences and similarities between GG and HU. SO2 results indicated minor Fe-sulfate in both HU and the lower GG target. Evolved HU CO2 patterns and GG were similar and consistent with oxidized organic C phases. HU and GG had similar evolved HCl patterns attributed to the chlorides. Hydrated salts were indicated by similar 240°C H2O peaks in HU and GG. However, GG had a 445°C smectite H2O peak which was absent in HU. These results suggest multiple alteration events where fluids that moved along the contact weathered smectite, sulfate and chloride from HU were then followed by events that redeposited only sulfates and chlorides to HU.
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