Multiproxy constraints on Central Paratethys Sea and Lake Pannon paleoclimate and paleoenvironment transitions during the Middle-Late Miocene (Danube Basin, Slovakia)

Abstract

The Danube Basin represents a northwestern depocenter of the Middle Miocene Central Paratethys Sea, which was succeed by the Late Miocene Lake Pannon. Although this is an extensively examined area, the application of multidisciplinary studies has proven capable of drawing attention to novel information concerning the depositional environment. Thus, this study aims to reveal climatic and paleoenvironmental changes by using both archive and fresh data drawn from biomarkers, palynology, sedimentology, and geochemistry. The article also addresses the quality, quantity, and thermal maturity of organic matter in relation to hydrocarbon potential. In general, the beginning of Serravallian stage relates to a regression forced by the development of the Antarctic icesheet followed by a pronounced transgression. The results presented here show that the Central Paratethys Sea reacted to the late Badenian (Serravallian) flooding, by an event which triggered a dysoxic, but not euxinic, bottom waters. The climate remained warm and humid, with paratropical to subtropical forests on the continent. Several new depocenters developed during the Sarmatian and divided the depositional environments into a shelf-brake slope in the central part of the Danube Basin, and into deltaic and swamp environments on the basin margins. The climate changed to temperate, leading to the disappearance of subtropical taxa. A shallow lake and swamp environment developed at the beginning of the Pannonian (Tortonian), forcing a salinity decrease connected to the increase in humidity. The degree of hydrocarbon richness of the mudstones is generally fair to good, and the kerogen is of mixed marine-terrestrial origin (II and III). Nonetheless, sediments at the basin margin are clearly immature due to insufficient burial.