Transform faulting, extension, and subduction in the Carpathian Pannonian region

Abstract

The Carpathian arc formed during the Cretaceous to Miocene continental collision of Europe with a smaller continental fragment following southward and westward subduction of an oceanic terrane. During and after the last stages of thrusting in the outer Carpathians, a set of discrete basins opened up inside the Carpathian loop. These basins are regions of local extension, which appear to be associated with strike-slip faults. In general, northeast- and northwest-trending sets of conjugate shears reflect east-west extension of the intra-Carpathian region during the middle and late Miocene. Palinspastic reconstruction of the basins indicates approximately 75 to 100 km of extension, comparable to the magnitude of synchronous crustal shortening in the East Carpathians. Extension may have occurred to accommodate continued westward (A-type) subduction after plate convergence was prohibited by geometrical constraints and suggests that in this region Miocene subduction is driven by forces acting on the downgoing plate.