2023 CSDMS meeting-083


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Impacts of changing subduction morphology on orogenic growth and foreland basin sedimentation

Xuesong Ding, The University of Texas at Austin Austin Texas, United States. xuesong.ding@beg.texas.edu
Carolina Lithgow-Bertelloni, UCLA LOS ANGELES California, United States.
Federico Davila, Universidad Nacional de Córdoba Córdoba , Argentina.

Along Andean-type convergent margins, the preserved stratigraphic successions in retroarc foreland basins record complex interactions between oceanic plate subduction, overriding lithosphere deformation, and surface processes. Modeling their interactions and their impacts on basin stratigraphy helps to distinguish the geological footprint of the operating processes. We use a source-to-sink landscape evolution model, Badlands, to investigate the basin stratigraphic formation in response to changes in subduction morphology, hinterland orogenic uplift, overriding lithosphere strength, and surface erosional efficiency. Our modeling results reveal distinguishable responses of basin sedimentation to the imposed tectonic and surface forcings. Firstly, with sufficient sediment supply (i.e., the basin is filled with sediments), subduction at higher slab dip leads to development of shallower and narrower basins, with increasing volume of fluvial and shallow-water deposits accumulation. For mechanically thicker overriding plates, a deeper foreland basin tends to develop, though the basin width does not show consistent changes with increasing lithosphere strength. When sediment supply is further enhanced by either increasing orogenic uplift rate or surface erodibility, the basin sedimentation extends horizontally while the basin depth changes in an opposite way. Secondly, our basin subsidence analysis reveals strong impact of flexural rebound at the foredeep on modifying the basin morphology and strata dipping. We further found positive correlations between the flexural rebound and the progradation of fluvial deposits at the foredeep. Lastly, by normalizing the basin width to orogenic belt width and basin depth to maximum foreland flexure, we categorize the basins to be accommodation-dominant and supply-dominant, which helps to evaluate the impact of varying each contributing process on the basin development. Overall, our source-to-sink models reveal the complex interactions between surface and tectonic forcings, and highlight the huge potential of extracting their signals from the geological record.