Landform evolution of Oudemans crater and its bounding plateau plains on Mars: Geomorphological constraints on the Tharsis ice-cap hypothesis

In this study we address the question of whether Tharsis rise that occupies ~25 % surface area Mars was once covered by an ice cap, and sudden ice-cap melting responsible for catastrophic development Late Hesperian (3.5-3.6 Ga) circum-Tharsis giant (>1000s km in length) outflow channels. To achieve goal, conducted geomorphologic mapping across Oudemans crater basin (~125 diameter) at elevations ~2.7 to ~5.0 its bounding plateau plains ~5.3 ~6.7 central rise. Our work shows Oudemans-impact-induced landforms were superposed a suite younger landform assemblages, which consist horn-like peaks, arête-like ridges, cirque-like depressions, hanging-valley-like features, trim-line-like escarpments, lobate striated, pitted hummocky terrains, features resembling drumlins, crag-and-tails roches moutonnées. A plateau-plain striated terrain on exhibits streamlined linear ridges are 400-2000 m wide up ~17 long. The average length-width ratio (~9), shape, texture, associated washboard pattern morphological comparable mega-scale glacial lineations (MSGLs) Earth. Using well-understood Earth analogues as guide, interpret post-Oudemans-impact assemblages have formed during regional ice-sheet-style glaciation. We further suggest been generated fast-moving stream sheet filled 4-km deep crater-bounding volume glacier stored alone is estimated order ~200,000 3 . shape inferred glacier-induced their cross-cutting relationships require early northward-flowing northward-advancing glaciation, followed southward-flowing northward-retreating size-frequency distribution craters top interpreted glaciated mapped yields glaciation age ca. 3.5 Ga, coeval with along 2000-km long Valles Marineris trough zone east area. also Although our supports hypothesis, full extent cap within possibly beyond remains unconstrained. • Geomorphologic reveals (~3.5 western end possible lineation (MSGL) present next basin. may total 0.2 million cubic volume. from supporting hypothesis. formation channels, suggesting genetic link.