Erosion-driven uplift and tectonics at Valles Marineris, Mars

The morphology and geophysical signature of the Interior Layered Deposits (ILDs) within the Valles Marineris troughs on Mars suggest that the deposits were previously more extensive and have subsequently eroded to their present state. This erosion would have had significant geodynamic and tectonic consequences as the lithosphere responded to the resulting enormous mass-deficit. It is likely that the flexural uplift due to sediment erosion played a large part in the evolution of the canyon system. In this study, I model the topographic and gravitational effects of ILD erosion, as well as the resultant stresses that this process would generate in the lithosphere. The results show that the flexural response to ILD erosion for elastic lithosphere thicknesses of 100-150 km best reproduce the observed gravity and topography of the region. The stresses associated with this flexure are large in magnitude and played a role in the subsequent regional tectonics. This is evident in the orientations of secondary tectonic structures both within the ILDs and on the surrounding plateaus that match the flexural stresses modeled here. The consistency between the model predictions and the observed gravity, topography, and tectonic record provides evidence that the troughs likely formed sediment-filled, with the erosion of those sediments constituting the final major phase in the development of Valles Marineris.