Mapping Carbonates and Associated Minerals on Mars

Carbonate and phyllosilicates are essential to understanding the ancient Martian environment, as well as the geologic evolutionary history, especially during the Noachian period. The presence of phyllosilicates is indicative of the aqueous solution in the form of water and the alteration processes. Carbonates are indicative of liquid water with neutral-to-alkaline pH, and a thick CO2 rich atmosphere. Today, Mars has a thin atmosphere (<10mbar) dominated by CO2[1]. However, ancient Mars had a much thicker atmosphere (100mbar-2bar)[2]. This atmospheric pressure would have allowed liquid water to exist on the surface of Mars. Widespread sulphate and phyllosilicate deposits are evidence of this [3,4]. A thick CO2 rich atmosphere and the presence of liquid water during the Noachian and pre-Noachian period suggest the presence of widespread carbonate deposits. However, on the contrary, few such deposits have been found. We present initial results from our work in understanding the environmental and geochemical conditions that led to the formation of carbonate deposits across equatorial Mars. In this effort, we also present an overview of our algorithm which uses an improved approach to Continuum Removal, as well as previously proposed spectral parameters for carbonates and phyllosilicates[5,6] to detect carbonates and associated minerals from CRISM hyperspectral data. [1] Craddock, R. A. et. al (2002) JGR 107 (E11), 5111. [2] PollackJ.B. (1987) Icarus, 71-2, 203-224. [3] Niles, P. B. (2013) Space Sci. Rev, 174, 301-328. [4] Bibring J. P. et. al. (2006) Science, 312, 400-404. [5] Dhoundiyal S. et. al. (2021), LPSC LII, Abstract #2548. [6] Dhoundiyal S. et. al. (2021), IPSC 2021, p.20.