A global survey of martian central mounds: Central mounds as remnants of previously more extensive large-scale sedimentary deposits

We conducted a survey of central mounds within large (>25 km diameter) impact craters on Mars. We use mound locations, mound offsets within their host craters, and relative mound heights to address and extend various mound formation hypotheses. The results of this survey support the hypothesis that mound sediments once filled their host craters and were later eroded into the features we observe today. The majority of mounds are located near the boundaries of previously identified large-scale sedimentary deposits. We discuss the implications of the hypothesis that central mounds are part of previously more extensive sedimentary units that filled and overtopped underlying impact craters. In this scenario, as erosion of the sedimentary unit occurred, the sediment within impact craters was preserved slightly longer than the overlying sediment because it was sheltered by the crater walls. Our study also reveals that most mounds are offset from the center of their host crater in the same direction as the present regional winds (e.g., the mounds in Arabia Terra are offset towards the western portion of their craters). We propose that this implies that wind has been the dominant agent causing the erosion of central mounds.