Constraining rates of thrusting and erosion: Insights from kinematic thermal modeling

Abstract

We present a thermal model of a simple thrust system that can be used to determine thrust rates and erosion rates from low-temperature thermochronology. Unlike previous models, this model incorporates the effects of erosion both during and after thrusting. In particular, we examine the modeled evolving thermal structure and pressure-temperature-time evolution of hanging-wall rocks that undergo fault-bend folding due to transport over a blind footwall ramp. In all cases, rocks cool as they move over the footwall ramp, potentially providing a common pinpoint for determining thrust rates. In the simplest case, low-temperature thermochronology of minerals that pass through their closure temperature over the ramp will yield details on thrust kinematics (thrust rate, timing of initiation, and duration of thrusting). Additional cooling ages of a more comprehensive sample suite can capture cooling due to erosion. In these latter cases, model results can place limitations on erosion rates.