Deformation, exhumation, and topography of experimental doubly-vergent orogenic wedges subjected to asymmetric erosion

摘要

We explore the effect of asymmetric erosion and dip angle of the indenter on the internal kinematics, deformation, and exhumation of an experimental doubly-vergent orogenic wedge during transient and steady-state flux conditions. We calculate displacement fields and derive strain and exhumation for several erosion and non-erosion cases, using particle image velocimetry (PIV) analysis. We apply calculated displacement fields to a simple heat equation to explore virtual evolution of thermal structure. Erosion exerts a primary control in the internal kinematics of the experimental wedge. In non-erosion cases, early-formed fore-shears rotate toward the indenter, such that the shear bands become steeper. This effect is more pronounced in prowedge erosion cases, where shear bands become very steep and even overturned. Conversely, retrowedge erosion results in back rotation of early-formed fore-shears, and the shear bands evolved to gently dipping structures. Wedge erosion, in combination with the condition of flux and topographic steady-state, increases density of fore-shears, and controls size, width, and topographic divide migration. Steeply dipping indenters produce overall gentle particle trajectories, and gently dipping indenters favor steep trajectories. Particle velocity, with respect to isotherms, increases where erosion is concentrated and near active fore-shears.