GEOMORPHOLOGICAL EVIDENCE FOR REGIONAL GLACIATION AT THE NORTHEASTERN MARGIN OF THE THARSIS RISE, MARS

Glaciation at the Mars equator has long been debated with important implications for understanding the Martian paleoclimate. We conducted photogeologic mapping in a region of Xanthe Terra centered at about 0° S, 45°W and across the northeastern margin of the Tharsis rise. Our work reveals a suite of landforms best explained by formation through supra- and subglacial processes. The studied landforms include chaos terrain, hummocky terrain, ridges, and valleys, along with features that we interpret as potential outwash channels, tunnel channels, kames, pit chains, and kettle formations. Analogous features on Earth suggest glacial mechanisms and processes in our study area. Our geomorphological analysis using images and DEMs from CTX, MOLA, and HiRISE reveals a system shaped by marginal melting of an ice sheet. Continued warming after the demise of the ice sheet caused melting of the permafrost, which in turn may have created the observed secondary thermokarst features and channel networks. Outflow channels are interpreted to be a result of pressurized permafrost melt.