In early 2019, the Curiosity rover embarked on a multi-year exploration of the Glen Torridon region, a topographic trough on the flank of Aeolis Mons, the sedimentary mound inside Gale crater, Mars. Orbital instruments have detected clay minerals over Glen Torridon, making it a primary target for Curiosity, because clay minerals are indicators of past interactions with water, and provide a medium favorable to the preservation of organic compounds. Understanding the context of formation of the clay minerals, and determining how much the sediments have been altered by water were among the objectives of the Glen Torridon campaign. Based on the chemical compositions measured by the ChemCam instrument, we show that the amount of water that interacted with the sediments was high enough to take away part of the most soluble elements. Nonetheless, similar levels of alteration have been observed in other parts of Gale, which implies that the signal observed from orbit is not controlled solely by the abundance of clay minerals in the rocks. Finally, in the highest part of Glen Torridon, we analyzed an area of light-toned rocks with distinct chemical compositions, which likely result from further modification by groundwater long after the main phase of alteration.

Reference: Bedrock geochemistry and alteration history of the clay-bearing Glen Torridon region of Gale crater, Mars. E. Dehouck, A. Cousin, N. Mangold, J. Frydenvang, O. Gasnault, O. Forni, W. Rapin, P. J. Gasda, G. Caravaca, G. David, C. C. Bedford, J. Lasue, P-Y Meslin, K. Rammelkamp, M. Desjardins, S. Le Mouélic, M. T. Thorpe, V. K. Fox, K. A. Bennett, A. B. Bryk, N. L. Lanza, S. Maurice, R. C. Wiens. JGR-Planets (2022).
DOI : https://doi.org/10.1029/2021JE007103