Geodynamics

Abstract

We investigate a role of the contact friction in thrusting within the framework of the critical taper theory and according to geological settings for orogenic belts including the Ukrainian Carpathians (in Early Cretaceous time). Finite element models are used to simulate tectonic compression of sedimentary rocks by submerged stage and take into account frictional slipping on the detachment horizon. We assume a simple wedge geometry (rectangular layer 60 km long, 1.5 km thick and 2.5 km deep), plane strain state, quasistatic process and use elastic constitutive relation. Mechanical loads include gravity, water pressure on top and lateral displacement (up to 0.5 km) from the left, whereas the right side is fixed. Numerical results show specific features of the inhomogeneous stress fields for small (0.01-0.5), middle (0.5-0.64), large (0.64—0.8) and overlarge (0.8-1.15) friction coefficients. The magnitude of the tangential contact stress controls the front between sliding and sticking zones. Stress trajectories enable to predict thrust structures using Mohr-Coulomb failure criterion.