Abstract
The aim of this thesis is to improve the understanding of source to sink systems in general and the Danube River Basin - Black Sea source to sink system in particular. The sediment sources of this system are formed by a number of mountain chains, including the Alps, Dinarides and
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Carpathians; a number of Paratethys basins serve as sinks. These mountain chains and basins formed as a result of the large-scale collision of the African and European plates, and a number of smaller continental blocks that were located in between. A coherent model for the formation and infilling of the Pannonian back-arc basin, a major Paratethys basin, is presented. Sequence stratigraphic concepts were applied to constrain the nature, timing and mechanics of extension in the southern part of the basin. It is shown that extension was a more continuous process than previously thought, and that it occurred simultaneously with shortening and exhumation near the plate margins. As extension-rates in the Pannonian Basin gradually decreased during the Middle and Late Miocene, the Central Paratethys was disconnected from the neighbouring Eastern Paratethys and the marine realm, effectively making the Central Paratethys a system of large lakes. Magnetostratigraphic results show that this major paleogeographic event occurred around 11.7 Ma. Based on this age, it is concluded that the uplift of mountain chains in the area was the prime cause of the isolation, while eustatic sea level fluctuations may have had a minor influence. After its isolation, the Pannonian Basin and other Central Paratethys basins were filled in with erosion products from the mountain chains surrounding the basins. New data presented in this thesis shows that progradation also occurred from the southern and eastern basin margins, in addition to the previously described progradation from the north western basin margin. Furthermore, it is shown that the effects of the Messinian Salinity Crisis on the Pannonian Basin were minor at most. A field study, reflection seismics and paleontological methods were used to identify the connections between the Pannonian Basin (Central Paratethys) and the Dacian basin (Eastern Paratethys). A significant regression occurred in the Dacian Basin during the late Sarmatian or early Maeotian; relative water levels in the Dacian basin dropped to the lowest point in post-Badenian times. The migration of Pannonian Basin (Central Paratethys) species to the Dacian Basin (Eastern Paratethys) show that a new connection formed between both basins during the Late Miocene. A new method is proposed that can be used to check whether uplift occurred recently in a region, based on the interplay between active tectonics and changes in drainage networks. Shifts of drainage divides are found to occur in the Carpathian bend area and the Transylvanian Basin, showing that although basin formation and mountain building processes have largely come to an end here, significant vertical movements still occur. The Danube is forming new tributaries downstream of the Iron Gates, where the river crosses the Carpathians. This suggests that the present-day course of the Danube near the Iron Gates formed during the Pliocene or Pleistocene
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