LATE JURASSIC-MIOCENE EVOLUTION OF THE OUTER CARPATHIAN FOLD-AND-THRUST BELT AND ITS FOREDEEP BASIN (WESTERN CARPATHIANS, POLAND)

Abstract

The Outer Carpathian Basin domain developed in its initial stage as a Jurassic-Early Cretaceous rifted passive margin that faced the eastern parts of the oceanic Alpine Tethys. Following closure of this oceanic basin during the Late Cretaceous and collision of the Inner Western Carpathian orogenic wedge with the Outer Carpathian passive margin at the Cretaceous-Paleocene transition, the Outer Carpathian Basin domain was transformed into a foreland basin that was progressively scooped out by nappes and thrust sheets. In the pre- and syn-orogenic evolution of the Outer Carpathian basins the following prominent periods can be distinguished: (1) Middle Jurassic-Early Cretaceous syn-rift opening of basins followed by Early Cretaceous post-rift thermal subsidence, (2) latest Cretaeous-Paleocene syn-collisional inversion, (3) Late Paleocene to Middle Eocene flexural subsidence and (4) Late Eocene-Early Miocene synorogenic closure of the basins. In the Outer Carpathian domain driving forces of tectonic subsidence were syn-rift and thermal post-rift processes, as well as tectonic loads related to the emplacement of nappes and slab-pull. Similar to other orogenic belts, folding of the Outer Carpathians commenced in their internal parts and progressed in time towards the continental foreland. This process was initiated at the end of the Paleocene at the Pieniny Klippen Belt/Magura Basin boundary and was completed during early Burdigalian in the northern part of the Krosno Flysch Basin. During Early and Middle Miocene times the Polish Carpathian Foredeep developed as a peripheral foreland basin in front of the advancing Carpathian orogenic wedge. Subsidence of this basin was controlled both by tectonic and sedimentary loads. The Miocene convergence of the Carpathian wedge with the foreland resulted in outward migration of the foredeep depocenters and onlap of successively younger deposits onto the foreland.