Landscape evolution constrained by the intraplate stress field: Direct coupling of tectonics and the influence of biota on long-term geomorphic development in the Chilean Coastal Ranges

Investigator Names and Contact Info:

• Kurt Stüwe (Geology / Neotectonics). Department of Earth Science, University of Graz, Austria
• Jörg Robl (Geology / Numerical Modelling). AG Geology, University of Salzburg, Austria

Chilean Collaborators Involved:

• Martin Reich (Geochemistry, Ore Deposits). Department of Geology, University of Chile, Santiago, Chile

Project summary:

This project has no precursor project in EarthShape Phase 1 and is an entirely new contribution to Phase 2. It aims to explain the curious observation that the relationship between slope and elevation in the topography of the Chilean Coastal Ranges changes systematically from north to south. This may be interpreted in terms of the influence of biota, because it is consistent with erosion being a function of the observed vegetation gradient. The region presents therefore a unique opportunity to investigate how landscape evolution models can be modulated for biota. For the project it is planned to use a numerical model developed by PIs in Austria that allows the modelling of surface processes on a mechanically coupled, deformable grid. Within this model we will use the well-constrained intraplate stress field of the Chilean Coastal Ranges and its evolution since the Miocene as boundary conditions to describe rock uplift. The surface process model of our code will then be modulated for the observed vegetation gradient until the observed surface uplift and slope-elevation distributions are reproduced. The result of the project will be a quantitative tool (a biota-modulated erosion law) which describes the relative importance of biota and tectonics on erosion processes in surface process models.

The project is an invited (Austrian) addition to EarthShape (Phase 2, cluster 5) because: (a) the use of the Chilean intraplate stress field is missing in the programme portfolio, (b) the numerical code used herein is not available in Germany and (c) the question tackled crucial to the priority programme. The project is laid out for the duration of one year and will provide its results to the substantially longer running overall EarthShape project. The project is paralleled by a more thorough application to the Austrian Science Fund FWF that involves a 3-year investigation of a related subject.

update: The project was not funded.