Constraints on the Depositional and Diagenetic History of the Glen Torridon Clay-Bearing Unit from the Mars Science Laboratory Sample Analysis at Mars Instrument Suite - INSU - Institut national des sciences de l'Univers Accéder directement au contenu
Communication Dans Un Congrès Année : 2020

Constraints on the Depositional and Diagenetic History of the Glen Torridon Clay-Bearing Unit from the Mars Science Laboratory Sample Analysis at Mars Instrument Suite

B. Sutter
  • Fonction : Auteur
D. Archer
  • Fonction : Auteur
Caroline Freissinet

Résumé

The Sample Analysis at Mars (SAM) instrument suite analyzed samples from three groups within the Glen Torridon (GT) clay-bearing unit: the sample Kilmarie (KM) from the Jura member, Glen Etive (GE) from the Knockfarril Hill member (KHm), and Glasgow (GG) from the Fractured Intermediate Unit (FIU). SAM also analyzed Hutton (HU), from near the unconformity between the FIU and overlying Greenheugh Pediment (GP). X-ray diffraction of GT samples showed large abundances of smectite clay minerals and relatively low amounts of well-crystalline hematite. SAM evaluated mineralogy through evolved gas analysis mass spectrometry (EGA) while detailed organic chemistry was examined by pyrolysis gas chromatography mass spectrometry (py-GCMS) (KM, GE, GG, HU) and a derivatization experiment (GE). EGA H2O data indicate that smectites are dominantly Fe-rich dioctahedral smectites (e.g., nontronites), which are consistent with open system hydrologic environments. H2O data also indicates minor minerals such as Fe-talc (KM, GE) and Fe-montmorillonite (GG). SO2 data indicate Mg sulfates and Fe sulfates/sulfides in KM and GE, while GG and HU only have Fe sulfate/sulfide. No O2 and little to no NO was detected from the samples, suggesting no oxychlorine salts and little to no nitrate salts present. HCl evolved from all samples indicated chlorides, but KM evolved much less than the other samples and HU evolved much more. CO2 and CO data were consistent with partially oxidized organics (e.g., carboxylates) and possible carbonates. Py-GCMS did not reveal any clear native reduced organic compounds in KM. Py-GCMS of GE, GG and HU revealed a higher diversity of organics, and investigation of the most likely sources (background and/or indigeneous) is underway. Rocks at GE may most closely record the fluvial-lacustrine deposition with rocks at GG and especially HU affected by diagenetic fluids associated with the GP/GT contact. Diagenetic fluids could have influenced the change in sulfur mineralogy from GE to GG and HU. The proximity of KM rocks to the diagenetically altered Vera Rubin ridge may have facilitated diagenesis compared to GE, leading to fewer chlorides and a lack of clear native reduced organics in KM. SAM analyses suggest that varying degrees of diagenesis may have affected the mineralogy and organic preservation potential of GT rocks.
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Dates et versions

insu-04500839 , version 1 (12-03-2024)

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A. Mcadam, B. Sutter, D. Archer, H. B. Franz, J. L. Eigenbrode, et al.. Constraints on the Depositional and Diagenetic History of the Glen Torridon Clay-Bearing Unit from the Mars Science Laboratory Sample Analysis at Mars Instrument Suite. American Geophysical Union, Fall Meeting 2020, Dec 2020, Virtual Meeting, Unknown Region. pp.abstract #P070-04. ⟨insu-04500839⟩
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