Accretionary Orogens: Erosion and Exhumation

摘要

The effect of surface erosion upon the structural evolution of accretionary wedges was studied with reference to the Himalayas and the Olympic Mountains, Washington, USA, and simulated by physical modeling. It was established that erosion is a necessary condition for exhumation in accretionary orogens. Under condition of erosion, dome-shaped structures are formed in the wedge models, and the material of the lower layers of the wedge is exhumed on the surface. The geometry of faults that controls the raising of material to the surface, as well as the localization of maximum uplift and exhumation, is different for accretionary wedges with high and low values of basal friction. The way of material transfer through an accretionary wedge and the location of maximum uplift and exhumation in the wedge depend on the slope of the erosion surface. Investigation of the structure, evolution, and material transfer in laboratory models of accretionary wedges subject to erosion makes it possible to clarify the effect of erosion on structure formation and the direction and rate of exhumation in accretionary orogens.