Karst landforms in an interior layered deposit within the Coprates Chasma, Mars

Abstract

The Coprates Chasma forms part of the backbone of the Valles Marineris canyon system. In the westernmost part of the chasma in an embayment on the northern wall a mound of layered material rises from the chasma floor and displays a characteristic dome-shaped morphology. The mineralogical characteristics of the dome and its surroundings have been determined by analysis of the CRISM (Compact Reconnaissance Imaging Spectrometer for Mars) data (image HRL00003752). The unit shows the clear signatures of kieserite, an evaporite mineral also found on Earth. Through analysis of the M.RO. HiRISE (Mars Reconnaissance Orbiter High Resolution Imaging Science Experiment images) we have investigated the dome landforms and the possible processes involved in their formation and shaping in great detail. The analysis shows that the landforms observed clearly indicate the presence of solutional processes that made those karst landforms. The results of our observation also suggest that liquid water must have existed on the dome in the past for long enough for the solution features to be formed, and that the karst landforms investigated exhibit an older erosional age or shorter than the same landforms studied in a similar kieserite dome located within Tithonium Chasma, another graben of the Valles Marineris system.