ERC IceFloods

Mars is a hyperarid, global cryosphere, and likely has been for over 3 Gyr. However, during the so-called early Mars period 4-3.5 Gyr go, water flowed within thousands of valleys, in crater lakes, producing ancient deltas, building ice sheets, and possibly ponding in oceans. Surface liquid water was stable on Mars coinciding with the origin of life on Earth. However, this early benign climate collapsed with the continued loss of Mars’ atmosphere in the Hesperian period, ~3.5-3 Gyr ago. Outflow channels, megacanyons among the largest erosive landforms in the Solar System, date from this time. The largest one, Kasei valles, is so vast that the volumes of water involved in its formation were an important fraction of Mars’ total water amount, and its outflow could have filled an ocean . In the current view, Kasei Valles was formed by a megaflood sourced from the catastrophic release of a near-surface aquifer, building on the basis of terrestrial analogue comparisons.

The project IceFloods aims to challenge this view. In this project, the IceFloods team will explore the hypothesis that Kasei Valles was eroded by an ice stream, a region of channelized, fast-flowing ice within an ice sheet, based on its scale, location, and geomorphology, and reinvestigate the origin of other outflow channels under this perspective. Drawing from novel fluid dynamic simulations, analogue field work, geological mapping, and climate modelling, we will test the ‘Ice flood’ hypothesis, which if correct would radically change our understanding of Mars’ transitional Hesperian climate, the nature of its hydrological cycle, and the possibility of a Hesperian ocean. Outflow channels hold a key for understanding the collapse of Mars’ early climate and hydrological system, the end of global conditions able to support life, and the rise of the global cryosphere that would come to dominate Mars’ climate.