Drainage and Sedimentary Responses to Dynamic Topography

Abstract

Dynamic topography due to mantle flow contributes to shaping Earth's evolving landscapes by affecting sediment routing, which has rarely been explored in source-to-sink contexts. Here we design a generic model to investigate the impact of dynamic topography on both landscape evolution and stratigraphic formations. An imposed wave of dynamic topography propagates laterally under a fixed continent, exerting transient surface uplift and subsidence. We find that a migrating dynamic topography can induce significant drainage reorganizations and affect sediment routing from source to sink. Variations in sediment supply driven by the lateral migrating dynamic topography contribute to the formation of diachronous unconformities along the margin. The predicted sediment flux histories are then put into perspective with the Cretaceous sedimentary records along the Southern African margins. Finally, we demonstrate that correlating offshore depositional hiatuses and unconformities has the potential to constrain the spatiotemporal evolution of past dynamic topography events. Plain Language Summary Convective motion within Earth's interior result in transient upliftand subsidence of the surface is called dynamic topography. This process slowly shapes landscapes over millions of years and identifying its fingerprints in the rock record remains a challenge. This study uses numerical modeling to investigate the erosional and depositional response of landscapes to sea level change and to mantle flow. We show that unlike sea level change, dynamic topography reorganizes river flows and changes sediment supply to offshore regions, generating various stratal patterns. We model a simple circular landscape that evolves similarly to the southern African landscape between 140 and 66 million years ago and suggest sedimentary fingerprints to link the evolution of the Earth's surface to the dynamics of its deep interior.

Landscape responses to dynamic topography and climate change on the South African source-to-sink system since the Oligocene

“…We show the importance of taking climate, dynamic topography as well as erodibility together as forcing parameters and not only focusing on one main driver as they appear to be completely interdependent. We agree that mantle dynamics can cause rapid uplift associated with drainage reorganisation, and denudation over a short period of time (Ding et al, 2019). Braun et al 2013, also showed that low slopes associated with the motion of a continent over a fixed source of dynamic topography may lead to substantial, i.e., kilometre scale, and rapid surface erosion, through continental-scale drainage reorganization.…”

Global influence of mantle temperature and plate thickness on intraplate volcanism

“…Dynamic topography undoubtedly makes a profound contribution to relative sea-level changes, ancient oceanic circulation, fluvial drainage patterns, and sedimentary deposition 62 – 67 . Here, we have shown that intraplate magmatism, positive asthenospheric temperature anomalies and thinned lithosphere are closely related during Neogene-Quaternary times.…”

Constraining Plateau Uplift in Southern Africa by Combining Thermochronology, Sediment Flux, Topography, and Landscape Evolution Modeling

“…Block landscape models showed that continent-scale tilting during early Late Cretaceous uplift was necessary to reproduce the major pulse of sediment to the marine basins on the west coast at that time (Braun et al, 2014). Additional modeling of a generic continent subjected to a propagating wave of dynamic topography argued that the modeled sedimentary architecture was consistent with Cretaceous sedimentary archives from southern Africa (Ding et al, 2019). Modeling efforts focused on river profile shape have taken this approach a step further by comparing modeled and observed river profiles to invert for uplift histories that suggest that the high topography was developed in the last 30-40 Ma (Paul et al, 2014;Roberts & White, 2010;Rudge et al, 2015).…”