A Preliminary Regional Geomorphologic Map in Utopia Planitia of the Tianwen-1 Zhurong Landing Region

A geomorphologic map is an important step to understanding the geologic context and history of a site; here, we present an initial geomorphologic map for an area spanning 2226N, 108112E in the southern Utopia Planitia (UP) region on Mars. This site is of special interest because it contains the May 2021 landing site of the Zhurong rover from Tianwen-1. The map can help place Zhurong data into the regional geomorphologic context. Our mapping effort has detailed the distribution of 3 geomorphologic units and 11 features. Based on our map, we propose the following regional history. Lava and/or sediments infilled the UP basin. Pitted Cones then developed on top of the basin-filling material. Subsequently, the Plains Unit was emplaced and resurfaced much of the area, followed by the creation of impact craters. The formation mechanism for the Pitted Cones and other units remains an open question. UP exhibits many features that have been proposed to be evidence of lava or mud flows. Lander and rover data should help solve this scientific question. Given that the Tianwen-1 lander touched down in the Plains unit, observations by Zhurong may provide the in situ data needed to better understand the origin of Plains, which we suggest is, at least locally in our map area, the youngest deposit and is potentially responsible for widespread resurfacing of the region. Additionally, in situ rover exploration of nearby Pitted Cones may yield the mineralogical and lithological data needed to distinguish between an igneous or sedimentary volcanic origin for these enigmatic features. We anticipate that our map will provide context for interpretations of Zhurong observations and future high-resolution orbital images. This map covers a 4x4 degree area (222 km by 237 km) and provides a useful representative tool to extrapolate local rover observations to the southern UP region. With it, we are better able to categorize and describe the enigmatic features and regional geomorphology found in UP and constrain the processes that formed the observed landforms.