Recent volatile processes in Martian low-latitudes revealed by pitted-wall craters in the Zhurong landing region

Multiple lines of evidence have confirmed that volatile activity during the Amazonian period of Mars was driven by obliquity oscillates, but supporting geomorphological evidence is lacking in the Martian low-latitude regions. Pitted-wall craters (PWCs), which are a set of craters whose interior walls host single or clusters of pits that share raised rims, comparable sizes (hundred meters) and equator-facing aspects, could be related to volatile activity and may fill the evidence gap. Based on the images acquired by Tianwen-1 High Resolution Imaging Camera (HiRIC) and HiRIC-derived DEMs, this study conducted quantitative characterization of 473 PWCs and 827 pits in the region, and constrained the formation age of the structures by combining crater size-frequency distribution (CSFD) analysis of degraded impact craters. The results show that the pits exhibit complex morphology, gentle slopes, a strict equator-facing orientation and uniform depth, suggesting a formation mechanism related to late-Amazonian volatile activity. Considering the regional geological background, we infer that water was likely the volatile responsible for forming the PWCs. This finding implies that during the Late Amazonian, the Zhurong landing region still had the materials and conditions needed to form large-scale, volatile-related landforms.