Evolved gas and X-ray diffraction analyses of sedimentary rocks in Gale Crater, Mars: Results from the Vera Rubin Ridge to the Glen Torridon Clay Unit. - INSU - Institut national des sciences de l'Univers Accéder directement au contenu
Communication Dans Un Congrès Année : 2019

Evolved gas and X-ray diffraction analyses of sedimentary rocks in Gale Crater, Mars: Results from the Vera Rubin Ridge to the Glen Torridon Clay Unit.

Résumé

The Sample Analysis at Mars instrument evolved gas analyzer (SAM-EGA) has detected evolved water, SO2, CO2, CO, and limited O2 and NO in 4 samples from the Vera Rubin Ridge (VRR) to the Glen Torridon (GT) Clay Unit. Three samples (Duluth (DL), Storer (ST), and Highfield (HF), were collected over 50 m of up-section stratigraphy along a southeast traverse up and over Vera Rubin Ridge (VRR). The Kilmarie (KM) sample was collected in the GT unit to the east and 10 m below HF, which is the highest stratigraphic sample. The SAM-EGA heated samples to 870°C and measured evolved gas releases as function of temperature. Evolved CO2 and CO were consistent with oxidized organics (e.g., carboxylates). Evolved SO2 indicated crystalline and/or poorly crystalline Fe- and Mg-sulfate and possibly Fe-sulfide. CheMin X-ray diffraction data indicated CaSO4 minerals accounted for most S. Evolved H2O was consistent with the adsorbed water, hydrated salts, phyllosilicate interlayer water/structural OH, and possible inclusion water in mineral/amorphous phases. The SAM-EGA and CheMin X-ray diffraction data indicated all four samples consisted of feldspar, pyroxene, phyllosilicates, sulfates, low levels of magnetite, and X-ray amorphous phases. However, differences between KM (GT Clay unit) were noted relative to the other VRR samples. Nitrate and oxychlorine were detected in KM but not in DL, ST, and HF. The KM sample also had lower hematite, higher total C and 2:1 phyllosilicates than the DL, ST, and HF samples. Similar depositional/alteration history could have caused all these sediments to possess feldspar, pyroxene, phyllosilicates, sulfates, and low levels of magnetite. A distinct resistant/recessive unit observed in both VRR and GT also suggests that stratigraphy carries through the VRR into GT as part of same depositional unit (Fedo et al. this meeting). Subsequent post-depositional processes affected only DL, ST, and HF resulting in higher hematite, and less C and phyllosilicate than in KM. Nitrate and oxychlorine may have been initially been present in all samples but were subsequently leached from only the VRR samples. The inferred geochemical conditions were likely favorable for microbial habitability. Organic C may have been sufficient, but nitrogen was likely a limiting microbial nutrient in these sediments.
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insu-04508186 , version 1 (17-03-2024)

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B. Sutter, A. Mcadam, D. W. Ming, C. Fedo, C. H. House, et al.. Evolved gas and X-ray diffraction analyses of sedimentary rocks in Gale Crater, Mars: Results from the Vera Rubin Ridge to the Glen Torridon Clay Unit.. American Geophysical Union, Fall Meeting 2019, Dec 2019, San Francisco, United States. pp.abstract #P33B-06. ⟨insu-04508186⟩
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