Constraining Early Mars Glacial Conditions From Paleodischarge Estimates of Intracrater Inverted Channels

Abstract

Inverted fluvial channels are widespread on Mars, and along with valley networks, they provide evidence of flowing liquid water in the early period of the planet's geologic history. We previously described tributary ridge networks within a closed-source drainage basin crater in the southern highlands, which we interpreted as inverted fluvial channels that were fed by meltwater from the surface of cold-based glaciers located in crater wall alcoves. Here, we estimate both the paleodischarge within the inverted channels and the necessary melting rates for discharge sources in glacial alcoves. We find that paleodischarges of up to ∼7,000 m3/s were possible with melting rates exceeding 2,000 mm/hr in an extreme warming scenario, with lower rates potentially representing more gradual glacial ice loss. These end-member estimates can provide key constraints for further early Mars climate and landform evolution modeling.