Retroarc foreland basins document past oceanic subduction history

Abstract

Retroarc foreland basins are natural laboratories for reconstructing the history of oceanic plate subduction. However, disentangling that history from the basin stratigraphic record remains challenging due to lack of quantification of how oceanic subduction and other geological processes separately or collectively affect the basin sedimentation. We aim to partially fill that gap by modeling the stratigraphic record of retroarc foreland basins under various subduction and mountain building events. We systematically evaluate the impacts of four parameters - slab geometry (or slab dip θ), surface uplift rate (U), elastic thickness of overriding plate ($T_e$), and surface erosion efficiencies (${\kappa }_c$) - on basin geometry and stratigraphic patterns. Our results reveal that shallow basin geometries are promoted by high θ and U, and low $T_e$ and ${\kappa }_c$. Basin width increases as U and ${\kappa }_c$ increase, but exhibits no universal scaling with θ and $T_e$, due to its dependence on sediment supply to the basin. Progradation of fluvial deposits positively correlates to the magnitude of flexural rebound (uplift), suggesting a novel proxy for estimating lithospheric elastic thickness. Furthermore, our model demonstrates that slab flattening can drive large-scale depocenter migration, mirroring the patterns observed in the Cordilleran retroarc basins in North America. Lastly, by normalizing basin geometry, we categorize accommodation-dominant or supply-dominant basins, which helps to evaluate the relative contribution of operated processes on basin formation. This work advances quantitative linkages between stratigraphic architecture and the interplay of subduction dynamics, mountain building, and surface processes, offering predictive tools to extract past geodynamic and tectonic signals from stratigraphic records.