The Climate, Hydrology and Limnology of Martian Crater Lakes: Implications for Surface and Subsurface Habitability of Jezero Crater and late Noachian / early Hesperian Mars

Long-lived lakes are among the prime habitable environments on ancient Mars and are key targets for current and future exploration. Some of the best examples of such lakes are found in craters, including Gusev, Gale, and Jezero. Deltaic and sedimentary deposits, and geomorphic indicators in these craters preserve key constraints on the paleo-climate and paleo-lacustrine environment of Mars, and provide evidence for a stable hydrologic cycle. Our recent work on the formation of lake and sulfate-cemented sediments in Gale has shown the importance of considering both surface and subsurface components of the hydrologic cycle. Moreover, these components have very different implications for habitability. The surface hydrology (precipitation driven runoff) is responsible for carving channels and forming deltas. In cold environments on Earth, land to lake transport of material via runoff dominates the lake chemical budget. However, the subsurface hydrology (base flow to lakes) plays a key role in the long-term stability of lakes, and has implications for chemical and thermal stratification in lakes. Thus, understanding the relative surface and subsurface hydrology has important implications for the habitability of early Mars lakes. Jezero crater is a prime candidate for a past habitable environment, with deltaic deposits and outlet breach morphology suggesting a long-lived lake, and mineralogy consistent with a neutral pH lake environment. Likewise, habitable conditions have been found in closed-basin lakes, such as Gale and Gusev, with evidence for long-lived lakes and active hydrology. Apparent differences in the hydrologic conditions and wide variations in the final deposition states of Jezero, other open-basin lakes in the surrounding region, Gale, Gusev, and closed-basin lakes in Arabia Terra and Meridiani Planum indicate a diversity of past habitable environment. However, it is not clear whether these differences reflect unique hydrologic conditions at these craters or a change in climate or hydrologic conditions with time. With abundant evidence of long-lived lakes and constraints on past lake levels in Jezero and other crater lakes, the goal of this project is to explore the lake and climatic settings of crater lakes on Mars.

This project utilizes an integrated atmosphere-surface-subsurface hydrological model to Jezero and the surrounding open-basin lakes to relate surface conditions to climatic conditions. This will constrain the climate and hydrology required for a stable, neutral lake in Jezero and the open-basin lakes in the surrounding region. We explore the relative importance of surface and subsurface flow assuming both an integrated hydrologic system and a hydrologic system in which fluvial activity was driven by melting ice. This hydrological model is also applied to other crater lakes on Mars and conduct a comparative analysis of the hydrology and limnology of Jezero (proposed above) with closed-basin lakes of Arabia Terra, Gusev, and Gale (previously studied). Modeling a diverse suite of crater lakes will allow us to investigate the influence of surface and subsurface hydrology, the climate evolution, and timing of these habitable environments, which has implications for the habitability of lakes throughout Mars past.