Erosion and the mechanics of shallow foreland thrusts

Abstract

A simple model for the effects of erosion on the geometry and mechanics of shallow foreland thrusts allows prediction of maximum stable length of the thrust toe, location of initial failure within the toe, if total thrust displacement exceeds the maximum stable length, and estimates of average pore fluid pressures along the fault during thrust advance. For ‘typical’ rates of erosion and thrust advance, the maximum stable length of the toe may be very large (over 50 km) for relatively low values of fluid overpressure. Application of the theoretical results to the Keystone-Muddy Mountain thrust of southern Nevada predicts: maximum stable length, location and degree of imbrication in agreement with observation; relatively low pore fluid pressures along the fault (λ between 0.5 and 0.6), and a rate of thrust advance between 4 and 8 km Ma −1.