Geologic structure of the Vera Rubin ridge, Gale crater, Mars

Abstract

Mount Sharp is a 5 km high mound of lithified sediments in the center of Gale crater on Mars. The Curiosity rover has been traversing this field site since its arrival in 2012. Curiosity has revealed a complex depositional and diagenetic history at Mount Sharp, which has been hypothesized to include a stable fluvio‐lacustrine period responsible for sediment accummulation at the base of the mound. We study this history by examining the bedding geometries of exposed bedrock along the traverse. Prior to landing, orbital measurements suggested the stratigraphy typically ranges between 2‐5° from horizontal and is always oriented radially outward from the center of the mound. Terrestrial lacustrine basins display horizontal to shallowly dipping beds oriented towards the center of the basin. We determine the structure of bedding planes at Mount Sharp with in situ Mastcam and Navcam stereo topographic data from the Curiosity rover on the resistant strata of the Vera Rubin ridge at 24 sites along the Curiosity traverse in addition to long baseline Mastcam stereo and orbital stereo techniques. From this integrated approach, we report a shallow dip (2‐7°) to the northwest, away from the central sedimentary mound. This result suggests that layering observed from orbit represents true depositional strata, rather than diagenetic horizons, and are an accurate measure of geologic structure. Additionally, these measurements have major implications for quantifying the vertical extent of the stratigraphy through which Curiosity has traversed.