Preservation of Late Amazonian Mars ice and water-related deposits in a unique crater environment in Noachis Terra: Age relationships between lobate debris tongues and gullies

Using martian single and double layered ejecta craters to probe subsurface stratigraphy

“…At temperatures below, water vapour will condense onto the surface and diffuse into the soil to condense as ice (Mellon and Jakosky, 1993). Decreasing obliquity towards the current low of $25°has resulted in the present day thin atmosphere and the loss and redistribution, through freezing and evaporation, of past reservoirs of liquid water from the surface (Clifford, 1993;Morgan et al, 2011). Currently Mars has a low partial pressure of water vapour in the atmosphere (P part ) and equatorial temperatures which exceed the frost point of water, causing water ice to be unstable at the surface and in the shallow subsurface at latitudes equatorward of $60° (Mellon and Phillips, 2001).…”

“…These are interpreted as debris covered glaciers (Holt et al, 2008) formed from snow accumulation during obliquity of $45° (Forget et al, 2006) (an axial tilt around 40°is expected to have occurred frequently throughout Mars' history, Laskar, 2004). More generally, the high concentration of lobate debris aprons associated with the Hellas and Argyre basins may be indicating a significant volume of subsurface ice <500 Myr old (Fastook et al, 2011;Morgan et al, 2011). Ice in all the aforementioned regions is currently not stable today at the surface, with the modelled average ice-table depth in these regions ranging from as shallow as 20 cm to deeper than 3 m (Mellon et al, 2004).…”

Geomorphic signatures of glacial activity in the Alba Patera volcanic province: Implications for recent frost accumulation on Mars

“…Overall, debris tongues are V‐shaped from the top to the terminus and their flow follows a NW trend. Based on the pattern of flow, scale, and association with gullies, LDTs tend to resemble some previously identified young viscous flow features (VFFs); however, their formation age differs from that of VFFs [ Milliken et al ., ; Arfstrom and Hartmann , , Morgan et al ., ]. Their presence on the pole‐facing slopes of a crater lying within 45°–40° is adequate to suggest that late Amazonian climate underwent multiple shifts that often formed larger‐moderate‐minor sized glacial landforms on pole‐facing slopes at lower‐middle latitudes during the past.…”

“…On Mars, the terrains in the northern and southern hemispheres have undergone a significant glacial transition during the past 10 Ma, when a suite of glacial features had formed by episodic melting/sublimation of atmospherically emplaced snow/ice under spin‐axis/orbital conditions [ Berman et al ., , ; Dickson and Head , ; Kneissl et al ., ; Dickson et al ., , ]. This suite of glacial features includes formation of gullies, thermal contraction crack polygons, arcuate ridges, localized viscous flow lobes, lobate debris tongues, solifluction lobes, and a scalloped terrain on the floor, wall, and regions adjacent to the rim of impact craters [ Head et al ., ; Milliken et al ., ; Ishii et al ., ; Mangold , ; Berman et al ., , ; Dickson and Head , ; Dickson et al ., , ; Levy et al ., ; Kneissl et al ., ; Morgan et al ., , ; Johnsson et al ., ; Schon and Head , ]. Head et al .…”

Terrestrial rock glaciers: a potential analog for Martian lobate flow features (LFF)

“…The suite of Late Amazonian landforms in the middle latitudes (30˚-60˚ N&S hemispheres) has suggested that the last 10 million to 1 billion years of Mars is dominated by multiple episodes of glaciation resulting in flow of ice-rich material [1][2][3][4][5][6][7][8][9][10][11] . A class of ice-rich landforms resulting from flow of ice-rich material during the Late Amazonian glacial episodes includes lobate debris aprons (LDA), linear valley fills (LFF), concentric crater fills (CCF), viscous flow features (VFF) and lobate flow features (LFF).…”