Present-day mass wasting in sulfate-rich sediments in the equatorial regions of Mars

摘要

Present-day topographic changes are observed on steep slopes in equatorial regions of Mars that are associated with sulfate-rich sediments. Hydrated sulfates are known to be present in many sedimentary deposits on Mars. We document volume changes in the form of mass movements and gullies over these regions. We have estimated erosion rates of similar to 12 mm/yr (or similar to 1.2-120 mm/yr with uncertainties) over steep slopes on sulfate-rich mounds in Ganges Chasma, much higher than Mars average erosion rate near a few mu m/yr. At this rate, the mounds would have shrunk in diameter by similar to 18,000 km over 3 b.y., which greatly exceeds the width of the canyon, supporting suggestions that these sediments once filled the canyons. Due to the soft nature of typical sulfate-rich sediment, it is susceptible to mass wasting, and active eolian processes may remove loose material to maintain steep slopes. The water in hydrated sulfates could potentially be extracted and used as a resource for future humans on Mars, and our results suggest that such deposits would be mechanically weak.