Topographic Evolution and Climate Aridification during Continental Collision: Insights from Computer Simulations.

Area of Science:

• Earth Sciences
• Geodynamics
• Climate Science

Background:

• Understanding the interplay between tectonics, sediment transport, and climate is crucial for explaining Earth's topographic evolution.
• Previous studies have used numerical models constrained by thermochronological and geomorphological data at various scales.

Purpose of the Study:

• To present a novel numerical model simulating the interaction of tectonics, sediment transport, and climate at the continental scale.
• To quantify feedbacks between these processes using a synthetic scenario inspired by the India-Asia collision and Tibetan Plateau growth.

Main Methods:

• Developed a unified computer program integrating a thin-sheet viscous model for continental deformation.
• Incorporated a stream-power surface-transport approach and flexural isostasy for foreland basin formation.
• Included an orographic precipitation model to simulate continentality and rain shadow effects.

Main Results:

• Identified a positive feedback between erosion and crustal thickening, locally increasing deformation rates by up to 50% where orographic precipitation is concentrated.
• Climatically-enhanced deformation occurs predominantly on the upwind flank and syntaxes of growing plateaus, potentially explaining tectonic features in the Himalayas.
• Continental topography appears largely insensitive to climate at the continental scale, though climate significantly impacts sediment trapping in basins like the Tarim Basin.

Conclusions:

• Complex interactions between climate, drainage, and tectonics suggest that steady-state topography at the continental scale is unlikely.
• The model provides insights into climatically-driven tectonic variations and their influence on landscape evolution.