MAPPING HYDRATED SULFATE MINERALS IN GALE CRATER, MARS

Gale crater is a 154 km diameter impact crater that resides along the global topographic dichotomy of Mars and is currently being explored by the Curiosity rover. Orbital observations revealed significant occurrences of hydrated sulfate minerals in Gale, but their origin is still not well understood. Numerous studies (e.g., Irwin et al., 2005; Pelkey et al., 2004; Anderson and Bell, 2010; Milliken et al., 2010; Thomson et al., 2011; Le Deit et al., 2013; Fraeman et al., 2016, Sheppard et al. 2021) have investigated sulfates within Gale using orbital data, but the types of sulfate present (i.e., Fe-rich monohydrated sulfates, Mg-rich polyhydrated sulfates) have not been mapped and investigated in detail across the entire mound; consequently, many questions regarding the source and formation of sulfate within Aeolis Mons remain unanswered.

We are producing a geologic map that characterizes the spatial distributions of sulfate deposits and their stratigraphic relationships throughout Aeolis Mons focusing on the scale, juxtaposition, and setting of landform assemblages. Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) summary parameter maps were georeferenced to a 6m/pixel context camera images (CTX) basemap allowing for mineral compositions to be interpreted. New High Resolution Imaging Science Experiment (HiRISE) digital terrain models (DTMs) were produced to quantitatively evaluate the relationships of the observed sulfate occurrences to elevation. HiRISE images also allowed us to delineate relationships between the different sulfates and other units at a finer scale.

The distribution of sulfate minerals in Gale where CRISM coverage is available and in areas where it can be confidently extrapolated indicate their spatial distribution is more complex than previously observed. HiRISE and CTX imagery made extrapolation possible where there is no CRISM coverage, but it should be noted that interpretations based on extrapolation are not definitive. Through detailed mapping of sulfate occurrences in Gale crater, more informed comparisons can be made to sulfate occurrences on Mars as a planet, elucidating whether processes involved are globally or locally controlled.