Self-weight consolidation process of water-saturated deltas on Mars and Earth

Deltas are water-related sedimentary landforms commonly discovered on Mars and Earth. During the formation of a delta, the self-weight consolidation process reduces its porosity and thickness. Previous studies on the martian consolidation process either adopted the terrestrial consolidation rate or ignored this process altogether. However, the consolidation process may diverge on these two planets due to their different gravity regimes, which may further affect the delta morphology and lithification and the estimation of the delta formation timescale. In this study, we carry out a series of laboratory experiments to determine the basic parameters for modeling consolidation using water-saturated martian sediment simulants. The consolidation process is modeled with Gibson's 1-D consolidation model for deltas with different initial thicknesses (20–150 m) and different types of base drainage conditions (rigid bedrock and loose regolith). The modeling results suggest that for the delta area with fine grains, the settlement amount on Mars is lower than that on Earth, which indicates the martian delta to be looser, more erodible and more easily disturbed than the counterparts on Earth from the effects of the consolidation process alone. Higher delta channelization, more sediment deformations and post-deposition erosions before significant cementation are thus expected on Mars. More cementation/recrystallization is needed for martian deltas to be lithified. By using the simulated final porosity of martian deltas (0.45–0.46) and an updated timescale calculation formula, estimated delta formation timescale is reduced to be 32–44% of the previous results.