Light-toned strata and inverted channels adjacent to Juventae and Ganges chasmata, Mars

Abstract

Light-toned layered deposits on the plains adjacent to Juventae and Ganges Chasmata have been identified and analyzed with several instruments onboard the Mars Reconnaissance Orbiter, including HiRISE, CTX, and CRISM. Beds exhibit variations in brightness, color, polygonal fracturing, and erosional properties that are not seen in light-toned layered deposits within the chasmata. At both Juventae and Ganges, the light- toned layered deposits along the plains have associated features we interpret as fluvial, including sinuous ridges (inverted channels) that exhibit light-toned layering and an extensive valley system for the Ganges deposit. The strong correlation between the inverted channels and light-toned layered deposits suggests an association with fluvial-lacustrine processes, although pyroclastic and eolian activity may also be involved in their emplacement. The identification of potential fluviallacustrine layered deposits and associated valley networks suggests surface water flow in the Valles Marineris region that occurred for sustained periods during the Hesperian (3.7-3.0 Gyr).