Tristan Salles (USyd)

Adding stratigraphy to landscape evolution model: basin architecture on passive margins & peneplain preservation

First, I will present new results on the influence of dynamic topography on passive continental margin stratigraphy. Quantifying the interaction between surface processes and tectonics/deep Earth processes has been one important aspect of landscape evolution modelling in recent decades. Both observations and results from numerical modelling indicate that dynamic topography plays a significant role in shaping landscape through geological time. Recent research suggests that dynamic topography also has non-negligible effects on stratigraphic architecture by modifying accommodation space available for sedimentation. Using Badlands I will investigate the evolution of a continental scale landscape in response to transient dynamic uplift or subsidence, and model the stratigraphic development (looking at stratal stacking pattern, vertical cross-sections and wheeler diagram) on passive continental margins in response to sea-level change, thermal subsidence and dynamic topography.

Then, I will discuss using newly implemented erosion laws the role of bedload fluxes on the preservation of low-relief summit surfaces. Low relief upland areas form summit surfaces in many dissected mountain ranges. They are often distinguished by their conspicuous flatness compared to the surrounding dissected terrain. Such relict landscape generate two questions: 1, is preservation a random process, or is there a process that helps such surfaces to resist dissection, and 2, how come relict landscapes are generally exclusively composed of subdued terrain? Dissection of the landscape by renewed wave of incision is controlled by river erosive power. River incision is achieved by various processes, but one of the main contributors is bedrock abrasion by bedload. Here I will show how this process can explain the persistence of subdued topographies.