Characterization of a Lava Plain NW of Ascraeus Mons, Mars, Through Surface Morphometric Analyses and SHARAD Subsurface Detections

Abstract

The Martian lava plains are characterized by their extensive, low-relief surfaces, which are the result of numerous basaltic eruptions and feature a variety of volcanic landforms, including vents, cones, pits, and skylights. The combination of these features and impact craters yields a significant understanding of the planet's geological past and subsurface composition. However, the flat terrain presents a challenge to detailed morphometric analyses, while the unavailability of high-resolution Digital Elevation Models (DEMs) complicates the precise estimation of radar-based thicknesses and dielectric constants. To address these challenges, we investigated an ∼8,030 km2 area northwest of Ascraeus Mons within the Tharsis Region. Prior research documented Amazonian volcanic features in this region; however, precise thickness and permittivity values remained undetermined owing to insufficient surface features and limited exposures. An enhanced, multi-scale neighborhood analysis method, adapted from terrestrial and Martian applications, was utilized to define the boundaries of a shallow lava flow sequence and identify three previously unmapped volcanic vents. Subsequently, all available subsurface sounding radar data in the region were analyzed using a simplified method. The results demonstrate that shallow, low-relief lava flows overlie a series of laterally consistent subsurface units, suggesting that volcanic and sedimentary processes occurred in multiple phases. The combination of our unique morphometric methodology using radar sounding showcases the characterization of morphologically subtle features despite the constraints of available data. This study offers a methodological framework for the investigation of other low-relief Martian regions, enhancing our understanding of the planet's volcanic and stratigraphic evolution.