Was Gale Crater (Mars) Connected to a Regionally Extensive Groundwater System?

• Published in: Geophysical research letters 2021-03, Vol.48 (6), p.n/a
• Main Authors: Roseborough, V., Horvath, D. G., Palucis, M. C.
• Format: Article
• Language: English
• Subjects: Aquifers; Climate; Curiosity (Mars rover); Drying; Geomorphology; geomorphology: fluvial; Groundwater; groundwater hydrology; Groundwater levels; Groundwater table; Gullies; Habitability; Hydrologic models; Hydrology; hydrology and fluvial processes; Lake levels; Lakes; limnology; Mars; Mars climate; Mars craters; Mars rovers; Mars surface sediments; Modelling; Paleolakes; Planetary geology; sediment transport; Sediments; Storage; Surface water; Surface-groundwater relations; Water depth; Water sources; Water table
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2020GL092107

Gale crater, home of the Curiosity rover, contains some of the best geomorphic and sedimentologic evidence on Mars for large lakes during the Hesperian and Amazonian. Orbital data and rover observations of delta deposits and terminations of gully networks suggest several phases of stable lake levels. However, the regional extent, water source (groundwater vs. surface water), and climate during each lake stand are debated. Consistent gully network termination elevations (GNTEs) within Gale and 17 regional craters suggest that GNTEs record paleolake levels. Hydrologic modeling indicates these lakes may have been coeval and the result of a regional groundwater table, recording a drying trend from subhumid conditions to semiarid conditions. Crater counting indicates that most lake‐hosting craters impacted after ∼3.7 Ga and surface water persisted intermittently until the Early Amazonian, constraining the timing but not duration of lakes. This work has implications for understanding water sources and volumes affecting sediments investigated by Curiosity. Plain Language Summary We seek to understand Mars' past climate and habitability by studying its past water abundance, storage, and sources. Currently, the Curiosity rover is collecting in situ data from Gale crater, where there is evidence in the rocks and surface features of a series of large lakes. However, the water source for these lakes, whether groundwater, surface water, or both, is debated. Here, we use a combination of high‐resolution mapping and numerical modeling to show that there were likely numerous large lakes across the Gale crater region—and the distribution and size (i.e., lake area and depth) of these lakes are consistent with a regional aquifer that existed under a climate that transitioned from subhumid to semiarid conditions. It is difficult to constrain the timing of these lakes, but they potentially existed until the Early Amazonian. Key Points Consistent elevations of gully network terminations within 18 craters in the Gale crater region likely record paleolake levels Hydrologic modeling suggests that Gale was connected to a regional aquifer, recording a transition from a subhumid to semiarid climate Crater counting indicates most water activity occurred after ∼3.7 Ga, with evidence for lacustrine activity until the Early Amazonian