Sedimentation in Meridiani Terrae, Mars, Owing to Magma-ice Interaction When Tharsis Arose?

Introduction: Cold temperatures on Mars [1] and a thin atmosphere prevent the occurrence of water in liquid form on the planet. However, sedimentary rocks at Meridiani Terrae show aqueous sedimentation. Catastrophic outgassing due to the Tharsis rise would result in increasing temperature and pressure, enabling water to exist on the surface for short periods of time. Magma–ice interactions during intrusive events that correspond to peak periods of Tharsis volcanic activity have been proposed as possible origins of surface materials in Xanthe, Margaritifer, and Meridiani Terrae [2]. New images from the Opportunity landing site show what appear characteristic of sedimentary sequences including gradation and cross-bedding. Turbulent flow of sediment-laden water deposits grains in a graded sequence, such as is common in turbidites. Jokulhlaup deposits (sediments from subglacial outburst floods resulting from volcanic activity) in Iceland also show graded deposition [3], superposed by cross bedding structures, reflecting deposition during both the rising and falling limbs of the flood hydrograph.