90-4 Top-down: Perspective of Lithospheric Foundering from Surface Geology

Abstract:

The viscous removal of dense, gravitationally unstable lithosphere beneath thickened plateaus is increasingly recognized as a fundamental process of intraplate tectonics. Yet lithospheric foundering is transient, leaving only indirect evidence in present-day geophysical observations, and difficult to study except via numerical geodynamic simulations. Over the past decade, a growing number of studies have proposed that foundering-induced dynamic topography may produce sedimentary basin records that preserve evidence of lithospheric removal. However, distinguishing such basins from more conventional tectonic basins remains an unresolved challenge.

Existing sedimentary basin models were developed primarily for basins generated by flexural loading, extension, or strike-slip deformation and do not explicitly account for localized dynamic topography associated with lithospheric removal. As a result, interpretations of “dynamic rebound basins” often invoke foundering to account for unexplained subsidence, leading to ongoing debate over whether these basins are best explained by lithospheric removal.

In this talk I explore the requirements for a testable sedimentary basin framework linking lithospheric removal to observable surface deformation, stratigraphic architecture, and thermochronologic signals of exhumation. Although such a model must necessarily be simplified and provisional, it provides a set of working hypotheses that can guide targeted geological fieldwork and enable comparisons among orogenic systems. Ultimately, the goal is to determine when, and with what confidence, the sedimentary and structural record can reveal otherwise hidden episodes of deep lithospheric foundering.

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