CSDMSRDasilvaEPub_Lithology

The shrinking and expanding of basins: insights from a Landscape Evolution Model with high lithological contrast

Authors and Affiliation:

Renato da Silva, Pedro Oliveira, Pedro Val*

*CUNY Queens College - School of Earth and Environmental Sciences

Doi: 10.5281/zenodo.12738032

Abstract: Landscapes in a transient state can be described as areas that are undergoing topographical and geomorphological adjustments. In tectonically active areas, it is straightforward to interpret and reconstruct topography using transient geomorphic signals based on stream power theory. However, areas without tectonic activity are also rife with topographic transience but lack a clear trigger. Landscapes with heterogeneous lithological substrates present geomorphic signals of an ongoing transient state even when their geological context implies tectonic and climatic quiescence. Here, I propose to investigate the transient landscape response to the exhumation of heterogenous lithology. The main objective of this project is to quantify the influence of lithology on landscape evolution processes in the absence of tectonic activity. I hypothesize that divide asymmetries are created by the differential incision power each basin has at the lithologic transition. The differences are a function of the drainage area and the distance crossed over the resistant rocks. Our work is based on a LandLab simulation in which the synthetic DEM has a rock in its lower (southern) portion that is more resistant to erosion. The boundary conditions were configured so that only the southern part was open to the river system, which resulted in drainages flowing from north to south. The drainage basins was then analyzed from the same base level, controlled by the exhumation of the most resistant rock. Preliminary results indicate that basins with a smaller drainage area are subject to shrinkage processes after the exhumation of resistant rock in their outlet (base level). While the basins that had the largest drainage area gained area via river capture and divide migration, expanding their total area over time and thus shrinking the adjacent basins.

Note: this script was based on the "Stream power, channel steepness, and relief" script, writen by Nicole Gasparini and available at https://github.com/landlab/landscapemetricscourse/blob/main/streampowerchannelssteepnessnotebook.ipynb