Paleoenvironmental evolution of Central Paratethys Sea and Lake Pannon during the Cenozoic

摘要

Deep wells penetrated Cenozoic sedimentary record of two different basins: 1) Oligocene retro-arc basin which is buried under the 2) Miocene back-arc Danube Basin. This study is focused on biotic and abiotic proxies discussed in terms of existing biostratigraphical, paleoenvironmental and sedimentological data. Biotic proxies are represented by palynofacies and biomarkers (palynomorphs, AOM, phytoclasts, TOC, Pr/Ph ratio, steranes). Abiotic proxies are represented by inorganic geochemistry (e.g., CIA, Sr/Ba, Ga/Rb, Th/U, SiO2/Al2O3, C-org/P and enrichment factors). The biotic and abiotic proxies helped to refine the knowledge about the changes in redox conditions, salinity, depositional system, and paleoclimate. In the study area five temporally different environments are observed: 1) Sedimentation in the Oligocene fragment of the retro-arc Hungarian Paleogene Basin that took place on a highly proximal part of the shelf. A major dysoxic event connected with humid marsh environment is documented within (last Rupelian transgression; Ru4/Ch1-Ch2). 2) After a hiatus the Danube Basin initiated with early Badenian (Langhian) stable oxic to slightly dysoxic shelf with minor salinity changes (Lan2/Ser1-Ser2 transgression). 3) Late Badenian (early Serravallian) dysoxic deposition, similar in all basins of the Central Paratethys, was influenced by upwelling connected with the Ser2-Ser3 transgression. 4) Sarmatian (late Serravallian) dysoxic event associated with subsequent flooding (Ser3-Ser4/Tor1), which created shallow marginal marine environment. 5) Pannonian (Tortonian-Messinian) sedimentation took place on an oxic shelf of the Lake Pannon near a fluvio-deltaic source, most likely represented by the paleo-Danube delta system.