The hydrology of the Jezero crater paleolake: Implications for the climate and limnology of the lake system from hydrological modeling

Abstract

Jezero crater, the landing site of the Perseverance rover, hosts sedimentary fan deposits, aqueously altered sedimentary rock, and an outlet breach of the crater rim, all of which indicates that a long-lived lake (or lakes) once existed within the crater. The deltaic deposits in the crater may preserve evidence of habitable conditions within the past lake system, which would have been influenced by the climate and conditions of the past hydrological system within the watersheds and basin. However, the aqueously altered sedimentary deposits within Jezero are less extensive than those found in other crater lakes on Mars, like Gale with a crater filling mound of cemented sediment. In this work we use hydrological models of the past Jezero lake system to constrain the climatic and hydrological conditions by comparing model predictions to the proposed lake stands and mineralogy in the crater observed from orbit and by the Perseverance rover thus far. We then compare these results to Gale crater to understand the influence of basin hydrology on the depositional setting found within past crater lakes. We show that a lake forming at the outlet breach elevation or higher in Jezero requires a semiarid or wetter-arid climate, consistent with previous estimates. An integrated hydrologic system with seasonal variations similar to arid and semiarid climates on Earth results in a lake system at Jezero characterized by both surface and subsurface outflow from the lake. Outflow to the subsurface and through the outlet breach will remove dissolved solids from the lake system, mitigating large-scale evaporite cementation within the Jezero basin, which is in contrast to Gale crater, where subsurface inflow constituted a larger percentage of the total inflow to the lake and all loss was through evaporation due to the setting in a deeper impact crater. Furthermore, at hyperarid climatic and/or groundwater-driven hydrological conditions, lake formation within Jezero would have ceased while a lacustrine depositional environment would have continued at Gale. This highlights the importance of considering basin hydrology, in addition to climate, when interpreting lacustrine sedimentary deposits in craters on Mars.