Regional drainage of meltwater beneath a Hesperian‐aged south circumpolar ice sheet on Mars

Abstract

[1] Five sinuous valleys that begin near the margins of the Hesperian-aged Dorsa Argentea Formation (DAF) are examined using Mars Global Surveyor Mars Orbiter Laser Altimeter data. These valleys are carved into the surrounding Noachian cratered terrain and extend away from the DAF for lengths up to 1600 km before terminating in the Argyre basin 1-3 km below their starting elevations. The association of these valleys with the DAF, thought to be the volatile-rich deposits of a previously widespread circumpolar ice sheet, supports the scenario whereby the valleys formed contemporaneously with the DAF and served as conduits for drainage of meltwater associated with the melting and retreat of the ice sheet. Examination of the head regions of three of the valleys reveals pits and basins carved into the local deposits of the DAF closely associated with the valley heads. On the basis of the distribution of these pits and basins, their morphologies, size, spacing, and basal elevations similar to the nearby valleys, we conclude that the pits and basins represent the expression of the valleys within the DAF. We suggest that the pits and basins resulted from surface collapse of the deposits due to basal drainage of meltwater beneath the thinning ice sheet. Sinuous ridges within some of the basins appear similar to terrestrial eskers and further support this scenario.

Evidence of volcanic and glacial activity in Chryse and Acidalia Planitiae, Mars

“…Head (2000, 2001) identified possible kames, kettles, and eskers in the circumpolar regions. Head and Pratt (2001) and Ghatan and Head (2004) described putative meltwater drainage valleys and eskers in the southern circumpolar regions. Esker-like features have also been described in the Argyre basin (Carr and Evans, 1980;Howard, 1981;Kargel and Strom, 1992;Hiesinger and Head, 2002); Banks et al (2009) analyzed these landforms with higher spatial resolution data, confirming that they are most consistent with glacial eskers.…”

Variability in martian sinuous ridge form: Case study of Aeolis Serpens in the Aeolis Dorsa, Mars, and insight from the Mirackina paleoriver, South Australia

“…Sinuous ridges have been identified at a number of sites on Mars (e.g., Williams, 2007), including on large-scale alluvial fans (Moore and Howard, 2005), on several plateaus surrounding the Valles Marineris canyon system (LeDeit et al, 2010;Weitz et al, 2010), in Sinus Meridiani and Arabia Terra (e.g., Edgett, 2005;Williams and Chuang, 2012), in the Argyre basin, (Kargel and Strom, 1992), near the south pole (e.g., Kargel, 1993;Head, 2000aHead, , 2000bHead and Pratt, 2001;Ghatan and Head, 2004), as part of a fan-shaped complex within Eberswalde crater (Malin and Edgett, 2003;Moore et al, 2003), on an alluvial fan near the Mars Science Laboratory landing site in Gale crater (Anderson and Bell, 2010), and in Aeolis Dorsa (Burr et al, 2009).…”

A tale of two planets: geomorphology applied to Mars' surface, fluvio‐deltaic processes and landforms

“…Particularly debris fl ows found on lee slopes of pristine windgenerated mega sand dunes must have formed in water, as inferred from heights of levees in inner and outer bends of the debris fl ow channels by modelling transverse fl ow surface gradient and viscosity (Mangold et al, 2003), similar to debris fl ows found on terrestrial alluvial fans, e.g. on Svalbard, Norway, and Dry Valley, USA Alluvial fans have surface gradients between 0·02-0·1, probably formed by dilute and/or dense water-sediment fl ows ) Lake deltas with surface gradients >0·01 and, often, a steep lee-side slope, probably formed by dilute water-sediment fl ows or perhaps as fans that were subsequently eroded at their toes (Grin and Cabrol, 1997;Ori et al, 2000;Irwin et al, 2005;Hauber et al, 2009;Kraal et al, 2008) probably formed in association to (rock) glaciers (see Baker, 2001, for review), (Neukum et al, 2004) as well as a collapsing ice sheet (Ghatan and Head, 2004) Kettle holes and frost polygons found on likely ice-margins (Lane and Christensen, 2000;van Gasselt et al, 2005) and associated with many other ice-margin lake features Ghatan and Head (2004); Dickson and Head (2006) Pingos and surface ice some pingos are still uncollapsed indicating presence of near-surface ice (Dundas et al, 2008), and fractured surface ice is protected against sublimation by dust cover (Fig. 4) (Murray et al, 2005) At present, some of the martian water is stored in the soil mantle of Mars as ground ice ( Figure 4) and mixtures of water and carbon dioxide ice (Longhi, 2006).…”

“…The polar caps are much thinner than on Earth and shrink and grow with the seasons. The circumpolar basin harbours sinuous meltwater valleys, eskers and kettle holes (Ghatan and Head, 2004;Dickson and Head, 2006). Mega-outfl ow channels are directed off the Tharsis height.…”