Early Mars climate near the Noachian–Hesperian boundary: Independent evidence for cold conditions from basal melting of the south polar ice sheet (Dorsa Argentea Formation) and implications for valley network formation

For moderate values of Martian obliquity and atmospheric pressures above around 0.5 bar, the equatorial Noachian highlands become cold traps.

“As a result of this adiabatic cooling effect, for moderate values of Martian obliquity and atmospheric pressures above around 0.5 bar, the equatorial Noachian highlands (where most valley networks are observed) become cold traps, confirming a prior prediction by Fastook et al. (2012).”

Dynamic ice-sheet modeling suggests that polar surface temperature increases of 25-50 K from Amazonian (modern) values are required before wet-based glaciation of the Dorsa Argentea Formation could occur.

“Dynamic icesheet modeling (Fastook et al. 2012) suggests that polar surface temperature increases of 25-50 K from Amazonian (modern) values are required before wet-based glaciation of the DAF could occur, again suggesting episodically warmer climate conditions on early Mars.”