Sublacustrine depositional fans in southwest Melas Chasma

Abstract

Two depositional fan complexes have been identified on the floor of southwest Melas Chasma. The western fan complex is located near the center of an enclosed basin in southwest Melas Chasma and is composed of multiple lobes with dendritic finger‐like terminations. These fans are very flat and have a morphology unlike any other fan that has been previously identified on Mars. On the basis of the morphologic similarity of the western fan complex to the Mississippi submarine fan complex, we suggest that it may be a deep subaqueous fan depositional system. There are numerous channels on the surface of the western fan complex, and measurements of channel length, width, and sinuosity are consistent with channels observed on terrestrial submarine fans. The eastern Melas depositional fans are less well preserved and may be of deltaic or sublacustrine origin. Recognition of the fans supports earlier suggestions for the presence of a former lake in Melas Chasma and indicates that a significant body of water was present and stable at the surface of Mars for at least 102 to 104 years.

Dynamics of dilative slope failure

“…The model developed in this study shows that breaching can occur in any granular material with sufficient dilation potential. My work also provides a framework and motivation for considering the occurrence of breaching on the surfaces of other planets and moons (Dromart et al, 2007;Metz et al, 2009) where liquid and granular materials exist. Liquefaction slope failure is usually associated with clay-rich deposits; increase in shear stress in the deposit drives the elevation of pore pressures until the deposit liquefies and releases large volumes of sediments all in once (Terzaghi, 1956;Morgenstern, 1967;Lowe, 1976;Hampton et al, 1996).…”

Inferring the high velocity of landslides in Valles Marineris on Mars from morphological analysis

“…The lake subsequently drained toward north (Ori et al 2000;Chapman 2008, 2010;Lucchitta 2009;Metz et al 2009;Flahaut et al 2010;Lucchitta 2010;Sowe et al 2011;Warner et al 2013). Thus, depending on the timing of the lake disappearance in relation to the landslide events, it is possible that at least some of the most ancient landslides were subaqueous.…”

“…Whereas the surface of the lowlands in the northern hemisphere exhibits widespread indications of ice at higher latitudes (Mouginot et al 2012), only more recently has it been suggested that glacial conditions might have been achieved in the equatorial regions during some episodes of Mars Hesperian-Amazonian history (Head and Marchant 2003;Murray et al 2005;Fueten et al 2011;De Blasio 2011a;Gourronc et al 2014). Thus, different lines of evidence suggest that VM has been filled for a long period by subsurface or exposed ice (De Blasio 2011a;Gourronc et al 2014) or a lake (Ori et al 2000;Chapman 2008, 2010;Lucchitta 2009;Metz et al 2009;Flahaut et al 2010;Lucchitta 2010;Sowe et al 2011;Warner et al 2013;Fueten et al 2014). This work explores landslide morphologies also with the objective of providing more independent data on their depositional environment.…”

The science process for selecting the landing site for the 2011 Mars Science Laboratory

“…The proposed site targets layered sedimentary beds deposited in a postulated paleolake that was fed by tributaries of Hesperian age (Dromart et al, 2007;Metz et al, 2009;Quantin et al, 2005). Some of the beds may have been deposited in sublacustrine fans (Metz et al, 2009) and the depositional setting suggests significant water was present and stable for at least hundreds to thousands of years (Metz et al, 2009).…”