Paleolakes in the Northwest Hellas Region, Mars: Implications for the Regional Geologic History and Paleoclimate

Abstract

Hellas basin is one of the largest and oldest impact basins on the Martian surface. Its surrounding highland regions have undergone complicated geologic processes after the formation of Hellas basin. However, the geologic and climatic histories of the highlands surrounding Hellas are still unclear. Paleolakes provide us clues to answer these questions. In this study, we made a detailed investigation of paleolakes in the northwest Hellas region with high‐resolution imaging, topographic, and spectral data. A total of 64 paleolakes were identified with diameters larger than 4 km, in which 49 are newly reported. We calculated basic hydrologic parameters of the paleolakes and analyzed the sedimentary landforms, resurfacing processes, and aqueous minerals in the lake basins. Comprehensive analyses of the geomorphology, mineralogy, and age of the paleolakes revealed the geologic and climatic histories of the northwest Hellas region: a climate transition from warm and wet to semi‐arid happened in Noachian, and then lakes drained in a cold and dry climate in the early Hesperian, contemporary with or followed by a period of intense volcanic activity peaked around 3.3 Ga, and finally in the Amazonian, an extensive glacial event around 0.9 Ga resurfaced most of the paleolakes in the region south of 25°S. Our study also supports the existence of a “Hellas Ocean” and indicates that the Martian climate could have variations on regional scales and further studies are still needed to clarify the details.

Life on Mars: Clues, Evidence or Proof?

“…There are strong evidences that the whole surface of early Mars was habitable and several biomarkers were found (including microbialite/stromatolite-like structures and bona fide microfossils). Orbital and rover data reveal fluvial valley networks, paleolake deposits, alluvial fans/deltas entering these lakes, clearly revealing sustained precipitation during the Noachian, Hesperian and Amazonian periods, since 4.5 to 0.9 Gy ago, when an extensive glacial event resurfaced the paleolakes themselves [85,86].…”

Megatsunamis and microbial life on early Mars

“…Martian palaeo-lakes that formed in impact craters are mainly of glacial, fluvial, rainfalls and groundwater rise origin (Hargitai et al, 2018;Zhao et al, 2020;Boatwright and Head, 2021).…”

“…In lacustrine environments, phyllosilicate clays and evaporite sediments are abundant, which is a suitable sedimentological property for the preservation of microbial fossils (Anderson, 2012;Zhao et al, 2020).…”

Limited Recharge of a Steady Deep Groundwater Aquifer in the Southern Highlands of Early Mars

“…Open and closed crater lakes have been identified throughout the Noachian terrain, providing further evidence of standing bodies of water on the Martian surface (Cabrol & Grin, 1999;Fassett & Head, 2008b;Di Achille & Hynek, 2010). In both Argyre and Hellas, observations have been made supporting the possible presence of large standing bodies of water (Parker et al, 2000;Wilson et al, 2010;Dohm et al, 2015;Hiesinger & Head, 2002;Hargitai et al, 2018;Zhao et al, 2020). Many have also argued that an immense ocean once existed within the northern lowlands (e.g., Parker et al, 1989Parker et al, , 1993Carr & Head, 2003;Fassett & Head, 2008a).…”