Source regions and multiple water release events in valley networks of the Libya Montes region on Mars

Abstract

Martian valley networks have been cited as the best evidence that Mars maintained flow of liquid water across its surface. Although internal structures associated with a fluvial origin within valleys such as inner channels, terraces, slip-off and undercut slopes are extremely rare on Mars (Carr and Malin, 2000) such features can be identified in highresolution imagery (e.g. Malin and Edgett, 2001; Jaumann et al., 2005). However, besides internal features the source regions are an important indicator for the flow processes in Martian valleys because they define the drainage area and thus constrain the amount of available water for eroding the valley network. Furthermore, the morphology of the source regions and their topographic characteristics provide information about the origin of the water. On Mars valley networks are thought to have been formed by retreating erosion where the water is supplied from the sub-surface. However, the mechanisms that are responsible for the release of ground water are poorly understood. The three-dimensional highly resolved data of the High Resolution Stereo Camera (HRSC) on the Mars Express Mission (Jaumann et al., 2007) allow the detailed examination of valley network source regions.