Miocene evolution of sedimentary environments and paleogeographic relations of Pannonian (Carpathian) Basin

Abstract

The Miocene development of the Pannonian (Carpathian) basin is related to the collision of the European and African plates. The Alps and the Carpathians uplifted in the Miocene and, due to the arising extensional forces, in the area encircled by them a subsiding basin system formed. The rate of subsidence varied spatially and temporally. It reached its maximum in the Middle Miocene, when true deep-sea environments prevailed. In the Upper Miocene subsidence went on at a reduced rate and shifted towards the deep basins. The changes in the biota of the inland sea and the characteristic endemic animal life, recurring in the various stages, clearly indicate the paleogeographical links and alterations in the sedimentation environments, There are three tectonic stages in the evolution of the basin system: in the Eggenburgian there still was easy communication with the world ocean. In the Ottnangian the contacts were broken up and characteristic endemic faunas developed. At that time, the Pannonian Basin was only linked with the western and eastern basins of the Parathetys. In the Middle Miocene the rate of subsidence increased and broad sea arms opened towards the Tethys. This was the period when – within the Neogene – the richest biota populated the shallow and deep sea environments of sedimentation in the basin. The Upper Miocene was a period of basin infilling. In the Sarmatian the area was completely isolated from the world ocean and formed an inland sea. In the Pannonian the inland sea was dissected into a lacustrine system with typical brackish, deltaic and fluviolacustrine sedimentation environments. On the Sarmatian/Pannonian boundary the basin was also separated from the Parathetys. An unambiguous paleogeographical link could be found with the eastern Parathetys in the Pannonian. The Pannonian evolution of the basin is a history of desalinisation and infilling. On the Miocene/Pliocene boundary over most of the basin area was a fluvial plain and lacustrine and deltaic sedimentation was only limited to the deep depressions.