COMPARISON OF MORPHOLOGICAL DATING MODELS FOR CUMULATIVE REVERSE FAULT SCARPS

Abstract

Degradation morphology of scarps can be used to estimate the age of an episode of uplift: linear diffusion models for slope degradation provide analytical solutions relying on simplified geometry and kinematics. In this paper, we evaluate to what extent such models can be applied to date cumulative reverse fault scarps by comparing their predicted degradation coefficients with those of a more realistic numerical model. Two analytical models with increasing complexity have been considered; the CU and IU models represent the morphological evolution of a single vertical fault at a constant rate of uplift and that of a vertical fault shifting incrementally, respectively. Synthetic data are generated by a numerical model accounting for reverse faulting, linear diffusion, and gravity-controlled collapse. We show that for cumulative reverse faulting without folding, approximated models neglecting fault dip and gravitational collapse lead to valid estimates of the degradation coefficient in a lot of cases because gravitational collapse and reverse faulting are competitive geomorphic processes. We provide estimates of the shifts expected on the degradation coefficient according to neglected processes.