Surface Uplift Due To Time‐Varying Elastic Thickness in Continental Interiors.

If, as previously hypothesized, the effective elastic response of the lithosphere is sensitive to the imposed stress regime, then it may vary in time and produce distinctive geomorphic responses. Such effects will be at their most crucial in landscapes of low relief. Motivated by the existence of numerous small endorheic (internally‐drained) basins in central Australia, we examine the influence of changing elastic response in the presence of large embedded loads in the lithosphere underlying stable continental interiors. Focusing on the western Lake Eyre Basin and adjoining Lake Lewis basin—an area with a close correlation between drainage pattern and extreme Bouguer gravity anomalies—we devise a set of numerical simulations that incorporate the flexural response to time‐transient horizontal stresses. The simulations demonstrate that transient changes in the effective elastic thickness can drive topographic changes in low‐relief landscapes, including drainage capture and the development of endorheic basins, consistent with field observations. Plain Language Summary: Extreme density anomalies in central Australia suggest the presence of significant stress within the lithosphere, even though the region lies far from any tectonic plate boundaries. This in situ stress probably dates back to a mountain‐building period in the Paleozoic. The density anomalies correlate closely with drainage patterns and a set of internally‐drained catchments, suggesting an important relationship exists between the deep‐earth and landscape‐forming processes. We propose the driving mechanism is the result of changes in the rigidity of the lithosphere, which in the presence of in situ stress lead to surface uplift or subsidence. We use a landscape evolution model to show that topography similar to field observations can be simulated by imposing cycles of uplift and subsidence brought about by these changes in lithospheric rigidity over tens of millions of years. In consequence, the lithosphere must have fairly low rigidity counter to previously held ideas about continental interiors. Key Points: Loads embedded within the central Australian lithosphere produce large flexural responses that may evolve cyclically over timeSurface deflections induced by transient lithospheric rigidity can explain endorheic basins formed at wavelengths of order 100 kmCyclical behavior in lithospheric rigidity is consistent with the observed geomorphic record of erosion and deposition [ABSTRACT FROM AUTHOR]