Geodynamic Implications from Late Cenozoic Dynamic Topography and Landscape Evolution in the Eastern U.S.

The composition and dynamics of the mantle underneath the eastern U.S. remains debated. For example, previous mantle convection models proposed contrasting scenarios of dynamic topography, surface manifestation of flow induced sub-lithospheric stress, during the late Cenozoic period. Such inconsistency often arises from the differences in the choice of mantle viscosity and density distribution. Long-term, large-scale landscape evolution simulation represents a tool to examine different models of mantle flow through quantifying the impacts of their resulting dynamic topography on surface processes. For this study, we plan to use inverse mantle convection models, with different assumptions on mantle dynamic properties, to generate varying dynamic topography scenarios, and then to use landscape evolution simulations to investigate these scenarios for the eastern U.S. The eastern U.S. serves as an ideal place to test the effect of dynamic topography given its tectonic quiescence and richness in surface observation. To distinguish different dynamic topography scenarios, we will rely on comparing the predicted river drainage patterns and sedimentary records with the observational proxies. By finding the best-fit dynamic topography scenario, we hope to put new constraints on the regional mantle flow history over the late Cenozoic and implications on the nature of mantle dynamics.