Tectonics and exhumation of the Romanian Carpathians: inferences from kinematic and thermochronological studies

Abstract

The ultimate topographic expression of intra-continental mountain chains is established during continental collision. The Romanian Carpathians provide a key location for understanding the mechanics of collision during slab-retreat because the nappe stacking was not overprinted by back-arc extension, as commonly observed elsewhere. A review of existing kinematic and low-temperature thermochronological data infers that the collisional mechanics is significantly different when compared with high-convergence orogens. The shortening at exterior of the orogen was entirely accommodated by back-arc extension, the area in between simply rotated and moved into the Carpathians embayment. The roll-back collision is driven by foreland-coupling, a process that gradually accretes and exhumes continental material towards the foreland. The topographic expression of the Romanian Carpathians is both inherited from latest Cretaceous – Paleogene times, such as in the Apuseni Mountains or South Carpathians, and overprinted by the Miocene exhumation associated with the roll-back collision, as in the East or the SE Carpathians. The migration of exhumation towards the foreland continued during Pliocene-Quaternary times and is still active modifying the present-day topography in the SE Carpathians. The Transylvania basin is one of the best examples available of vertical movements induced by deep mantle processes in what is commonly referred as dynamic topography.