Foreland-directed lower-crustal flow and its implications for the exhumation of high-pressure-high-temperature rocks

Abstract

AbstractThermo-mechanical finite element models are used to study foreland-directed lower-crustal flow as a potential process to transport high-pressure-high-temperature (HP-HT) rocks from a continental collision zone to areas that have never experienced crustal thickening or deep burial. The numerical simulations show that lower-crustal rocks can indeed flow over substantial horizontal and vertical distances, provided a thermal anomaly reducing lithospheric strength exists in the foreland. As lower-crustal flow is a fast process compared with conductive heat transport and occurs subparallel to the isotherms, the resultingPTpath of the rocks exhumed will be characterized by near-isothermal decompression. Modelling results are applied to the Saxonian Granulite Massif in Eastern Germany, where HP-HT granulites have been exhumed beneath a marine sedimentary basin during the Variscan Orogeny.