Spatial resolution and the geologic interpretation of martian morphology: Implications for subsurface volatiles

Abstract

Viking orbiter images of Mars provide global coverage of the major geologic and tectonic provinces on the planet. However, only a fraction of the orbiter images are useful for assessing the processes responsible for the generation or modification of surface landforms. An example from Acheron Fossae illustrates that aeolian dunes visible at 9 m/pixel resolution are indistinguishable at 57 m/pixel resolution. Dunes in Acheron Fossae valleys lend support to an aeolian interpretation for lineated valley fill at this location; this result provides an alternative hypothesis for the proposed ice-rich interpretation of this terrain. Consequently, it seems unlikely that images with a spatial resolution >50 m/pixel can provide strong constraints on the relative importance of various geologic processes that have acted upon the surface. A survey of the best Viking Orbiter images with <10 m/pixel resolution revealed a variety of landforms, but none of these landforms necessarily requires the presence of subsurface volatiles for their formation. High-resolution images of proposed volatile-related landforms need to be identified in order to assess the role of subsurface volatiles in the generation or modification of Martian landforms.