Constraints on the rate of post-orogenic erosional decay from low-temperature thermochronological data: application to the Dabie Shan, China
Résumé
We have investigated whether low temperature thermochronological datasets can be used to constrain the rate of surface evolution during the post-orogenic phase of a mountain belt. We use a numerical method to solve the heat transport equation in the Earth's crust, including the effects of a changing, finite-amplitude topography and the resulting flexural isostatic rebound. We demonstrate that accurate estimates of the amount of relief loss can be obtained by applying a recently developed spectral method that is based on estimates of the relationship between age and surface elevation as a function of topographic wavelength. We also show that the rate at which topography decays with time following cessation of tectonic activity can be constrained from estimates of exhumation rate derived from the slope of ageelevation profiles collected across short wavelength topography. Using the Neighbourhood Algorithm to perform a thorough search through parameter space, we are able to find a tectonomorphic scenario that predicts age distributions compatible with a thermochronological dataset collected in the Dabie Shan of eastern China by Reiners et al.