Geomorphological Analysis of ExoMars Candidate Landing Site Oxia Planum

Abstract

The article is devoted to a detailed photogeological and topographic analysis of the surface in the region of Oxia Planum, which is the most likely landing site for the rover of the ExoMars mission. The landing site consists of two topographic domains (highlands and lowlands) separated by a sharp regional slope. The highland domain accounts for approximately 25% of the landing site. The main unit of this domain is lava plains with an absolute model age of 3.65 Ga. These plains extend to the west and cover almost the entire surface of the lowlands, where they are overlain by a relatively thin (first tens of meters) layer of material removed from the highlands during the period of fluvial activity. The age of its final phase is estimated at 3.53 Ga. The material to be tested by the ExoMars rover is mainly associated with the final accumulation phase and is represented by deposits of dark and light smooth plains within the lowlands. The material of the dark plains mainly consists of a more coarse-grained fraction of the highland lava plains redeposited near the topographic boundary separating the highlands and lowlands. Deposits of the light plains are dominant at the landing site and are represented by a finer fraction of the material of the lava plains and light mantle material, in which clay minerals are likely predominant.