EROSIONAL WINDOWS INTO ANCIENT SEDIMENTARY BASINS ON MARS

Large sedimentary basins are important archives of Earth history and it is unknown to what extent similar basins existed on Mars. It is difficult to identify buried deposits on Mars because most observations are limited to the planet’s surface, with few exceptions. Here, we tested the hypothesis that landscapes of networks of topographic ridges, abundant on the surface of Mars, form at erosional windows into thick, basin-filling river deposits accumulated over long timespans, in contrast to classical views as thin-skinned surface deposits that preserved fluvial landscapes at a snapshot in time. We used a numerical model to drive hillslope creep and differential erosion from the wind to simulate Mars-like exhumation processes, and we applied the model to basin-filling fluvial strata buried in the Gulf of Mexico on Earth, imaged using 3D reflectance seismology. Simulations produced remarkably martian landscapes. The preferential erosion of mudstone relative to sandstone channel belts created landscapes with complex patterns of intersecting ridges. Ridge cross-cutting patterns reflected the exhumation of channel bodies at different stratigraphic levels, exposing basin strata accumulated over 500,000 years. Fluvial ridges on Mars may reflect similar erosional windows into the interior of martian sedimentary basins, exposing an archive of long-lived aqueous processes.