Geological Evidence of Planet‐Wide Groundwater System on Mars

Abstract

The scale of groundwater upwelling on Mars, as well as its relation to sedimentary systems, remains an ongoing debate. Several deep craters (basins) in the northern equatorial regions show compelling signs that large amounts of water once existed on Mars at a planet‐wide scale. The presence of water‐formed features, including fluvial Gilbert and sapping deltas fed by sapping valleys, constitute strong evidence of groundwater upwelling resulting in long term standing bodies of water inside the basins. Terrestrial field evidence shows that sapping valleys can occur in basalt bedrock and not only in unconsolidated sediments. A hypothesis that considers the elevation differences between the observed morphologies and the assumed basal groundwater level is presented and described as the “dike‐confined water” model, already present on Earth and introduced for the first time in the Martian geological literature. Only the deepest basins considered in this study, those with bases deeper than −4000 m in elevation below the Mars datum, intercepted the water‐saturated zone and exhibit evidence of groundwater fluctuations. The discovery of these groundwater discharge sites on a planet‐wide scale strongly suggests a link between the putative Martian ocean and various configurations of sedimentary deposits that were formed as a result of groundwater fluctuations during the Hesperian period. This newly recognized evidence of water‐formed features significantly increases the chance that biosignatures could be buried in the sediment. These deep basins (groundwater‐fed lakes) will be of interest to future exploration missions as they might provide evidence of geological conditions suitable for life.

Fluvial Regimes, Morphometry, and Age of Jezero Crater Paleolake Inlet Valleys and Their Exobiological Significance for the 2020 Rover Mission Landing Site

“…According to Goudge et al (2015), these valleys are carved within a basaltic capping unit, suggesting that groundwater may have been involved in combination with overland flows, as observed elsewhere on Mars (e.g., Salese et al, 2019b). However, although the valleys present a paucity of downstream tributaries, their longitudinal and transverse profiles show that the main tributary has neither amphitheater head nor constant valley width as usually observed for sapping, but rather a progressive incision into the plateau with gradual deepening and enlargement of the main tributary (Fig.…”

Groundwater Control and Process Variability on the Equatorial Layered Deposits of Kotido Crater, Mars

“…An important role of groundwater in ELDs deposition in Arabia Terra was already suggested for the case of sulfate‐bearing materials (Andrews‐Hanna et al, , ; Allen & Oehler, ; Rossi et al, ; Andrews‐Hanna & Lewis, ; Pondrelli et al, , ; Michalski et al, ; Franchi et al, ) and for the clay‐bearing materials located in the deepest craters of Arabia Terra (Salese et al, ). In the specific case of the study area, groundwater might have acted by providing pressurized fluids rich in salts, gas, or sediments, which led to water upwelling and evaporite precipitation, and/or the emplacement of mud volcanoes.…”

“…We interpreted the basin‐wide and internal architecture of the ELDs and analyzed their morphologies, textures, sedimentary structures, and composition characteristics with the aim to understand the processes and environments of their formation. We then discuss our results to infer the geological setting and evolution of Kotido crater in the framework of Arabia Terra clay‐ and sulfate‐bearing deposition (Salese et al, ).…”

Sustained fluvial deposition recorded in Mars’ Noachian stratigraphic record

“…W hile the present-day Martian surface is generally dry and cold, its geomorphic record contains compelling evidence for the former presence of liquid water [1][2][3][4][5][6][7] . In addition to this rich geomorphic archive, Mars' increasingly accessible sedimentary rock record provides a repository of information from which to study how planet-wide patterns in deposition have changed over time.…”