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Communication Dans Un Congrès Année : 2022

Formation and destruction of clay minerals in Glen Torridon, Gale crater, Mars

Marine Desjardin
  • Fonction : Auteur

Résumé

From 2019 to 2021, the Curiosity rover explored the Glen Torridon (GT) region, a topographic trough located on the slope of Aeolis Mons, the central mound of Gale crater. GT corresponds to what was previously referred to as the “clay-bearing unit”, due to the detection of smectite signatures by orbital spectro-imagers. One of the objectives of this campaign was to better understand the context of formation of the clay minerals, as well as the overall alteration history of GT. Here, we used the ChemCam instrument to survey the major-element composition of the bedrock throughout the region. Overall, the GT bedrock is characterized by elevated values of the Chemical Index of Alteration (CIA), which indicates that the clay minerals were formed in a context of open-system weathering, i.e., through the interaction of the sediments (or their source rocks) with dilute meteoric fluids at relatively high water-to-rock ratio. We also observed geochemical variations correlated with outcrop expression – for example, in the northern part of GT, the spatially dominant type of bedrock has a distinctive “rubbly” appearance and displays enrichments in both K2O and SiO2 , which are best explained by the presence of illite or a mixed-layer illite/smectite phase. Finally, in the southern part GT, in an area of lighter-toned rocks named the Hutton interval, we found significantly lower CIA values that are correlated with reduced abundances of clay minerals. We interpret these “anomalous” compositions as a local diagenetic overprint, and propose that the clay minerals of the Hutton interval have been partially destroyed by the circulation of concentrated fluids late in the history of Gale.
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Dates et versions

hal-03922838 , version 1 (04-01-2023)

Identifiants

  • HAL Id : hal-03922838 , version 1

Citer

Erwin Dehouck, Agnès Cousin, Nicolas Mangold, Jens Frydenvang, Olivier Gasnault, et al.. Formation and destruction of clay minerals in Glen Torridon, Gale crater, Mars. 23rd General Meeting of the International Mineralogical Association, Jul 2022, Lyon, France. ⟨hal-03922838⟩
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