Interplay between subduction retreat and lateral extrusion: Tectonics of the Western Carpathians

Abstract

Analysis of brittle microstructures reveals three Tertiary deformation events in the Western Carpathians: (1) Late Paleogene bedding‐parallel extension; (2) Oligocene (?) to middle Miocene NNE‐SSW compression and ESE‐WNW extension; (3) post‐mid‐Miocene NW‐SE extension. These regional deformations, applied to crustal blocks in the intra‐Carpathian region, resulted from forces which were induced by the coupled plate tectonic processes of subduction retreat beneath the Carpathian arc and lateral extrusion from the Eastern Alps toward the Carpathian region. Material flow from the Alps spread toward east and NE, guided by sinistral strike‐slip zones along the NE trending continental margin. Subduction retreat was terminated by mid‐Miocene “soft” collision of the Inner Western Carpathians with the European foreland. Ongoing subduction retreat beneath the Eastern Carpathians caused post‐mid‐Miocene back arc extension forming the Pannonian basin. Extension spread into the Western Carpathians by reactivating the extrusion‐related strike‐slip faults as normal faults.