Search all library resources

Flexural Modeling of Foreland Basins

This contribution focuses on the e↵ect of laterally varying elastic thickness in the un- derlying lithosphere and thrust loading on foreland basin subsidence. I use numerical models to compare flexural subsidence patterns expected in basins with little lateral variation in crustal thickness (e.g., Chaco Basin in Bolivia) with those typical of strong lateral variations in this property (Magallanes-Austral Basin in Chile/Argentina). In the Chaco Basin case, the observed basin geometry is well modeled using an elastic beam with uniform rigidity. In contrast, the Magallanes-Austral Basin contains rem- nants of the Rocas Verdes backarc basin proximal to the Patagonian fold-and-thrust belt and transitions to unattenuated continental crust in the distal plate segment from the thrust front. As a result of this strong lateral variation in crustal thickness, flexural subsidence predicted by an uniform-rigidity elastic beam model is inconsis- tent with measured subsidence. Instead, a model with varying elastic thickness better reconciles the bathyal foredeep and the relatively long wavelength deflection observed in the Magallanes-Austral case. I further this analysis with non-dimensionalizing the varying rigidity model and explore the evolution of basin geometry as the thrust front horizontally expands. I find that the initial phases of basin development are flexurally driven, but as the topographic load expands horizontally, isostatic forces take over and the basin depth becomes dependent on the crustal loading configurations rather than on the properties of the underlying lithosphere. The modeled basin history also has implications for sediment patterns, as rigidity variations in the lithosphere can result in hinge-like subsidence that localizes deposition spatially instead of relative to the thrust front.

San guo yan yi zi liao hui bian

Qian zi wen