Formation of Martian gullies by the action of liquid water flowing under current Martian environmental conditions

Abstract

[1] Geomorphic evidence suggests that recent gullies on Mars were formed by fluvial activity. The Martian gully features are significant because their existence implies the presence of liquid water near the surface on Mars in geologically recent times. Irrespective of the ultimate source of the fluid carving the gullies, we seek to understand the behavior of this fluid after it reaches the Martian surface. We find that contrary to popular belief, the fluvially carved Martian gullies are consistent with formation conditions such as now occur on Mars, outside of the temperature-pressure stability regime of liquid water. Our model of the action of flowing pure liquid water produces the observed gully length distribution only at surface pressures and temperatures below the triple point where liquid water simultaneously boils and freezes and thus suggests that gullies were formed under conditions similar to present-day Mars. Our results suggest a typical flow rate of 30 m 3 /s to carve the gully channels. At least 0.15 km 3 has flowed across the surface of Mars to carve the gully systems observed today, and this would require an aquifer recharge rate of $10 À13 -10 À12 m/yr. The absence of gullies on Mars that are long enough to have been created above the triple point pressure argues that the atmospheric pressure has not been significantly larger than it is now since the origin of the gullies. This result may imply that Mars does not possess a significant reservoir of condensed CO 2 .

Rapidly reversible redox transformation in nanophase manganese oxides at room temperature triggered by changes in hydration

“…There are great diurnal temperature differences and sheltered basins with subsequent transient melting of ice (15)(16)(17) and craters where the atmospheric pressure is higher than average (18,19). In addition, very high salt concentration in Martian soils (20)(21)(22) may contribute to melting of ice in addition to an increase mineral surface dehydration by lowering water activity.…”

Downslope sediment transport by boiling liquid water under Mars-like conditions: experiments and potential implications for Martian gullies

“…Although evaporation has been considered in previous studies of water flow at the Martian surface (e.g. Heldmann et al 2005), the physical effects of boiling are usually not taken into account. divided into three types: (1) 'classical gullies' (Fig.…”

“…Malin & Edgett 2000;Gaidos 2001;Mellon & Phillips 2001;Gilmore & Phillips 2002;Heldmann & Mellon 2004;Heldmann et al 2005Heldmann et al , 2007Malin et al 2006); (2) melting of near-surface snow or ice in a warmer recent past (e.g. Costard et al 2002;Arfstrom & Hartmann 2005;Berman et al 2005;Head et al 2008;Védie et al 2008;Schon et al 2009;Williams et al 2009;Kneissl et al 2010;Raack et al 2012;Jouannic et al 2015); (3) melting of surface snow or ice under current climatic conditions (Christensen 2003;Head et al 2008); (4) CO 2 -supported flows (e.g.…”

“…Therefore despite its instability, liquid water flows remain a strong candidate for the formation of gullies in the past and present (e.g. Malin & Edgett 2000;Mangold et al 2003Mangold et al , 2010Reiss & Jaumann 2003;Miyamoto et al 2004;Heldmann et al 2005;Mushkin et al 2010;Reiss et al 2010;Conway et al 2015;Conway & Balme 2016).…”

“…Estimations of the volumes of water required to produce the observed changes on Mars are often based on a terrestrial understanding of the behaviour and transport capacity of stable water (Heldmann et al 2005;Pelletier et al 2008;Kolb et al 2010;Parsons & Nimmo 2010). However, recently, Martian-like pressure experiments have highlighted the unusual behaviour of boiling water in sediment transport physics Raack et al 2017).…”