Palaeogeographic significance of tidal deposits: an example from an early Miocene Paratethys embayment, Northern Hungary

Tide-influenced deposits can be used in palaeogeographic reconstructions because they are good indicators of open marine connections. An example is presented from the Eggenburgian (late Aquitanian-early Burdigalian) of the North Hungarian Bay. This bay was part of an inland sea, the Paratethys. Tide-influenced deposits prove that tidal motions in the North Hungarian Bay were locally amplified. This required a free propagation of tidal waves from the open ocean through the Paratethys into this embayment. Since all seaways towards the Mediterranean were closed during the early Eggenburgian, the only connection between the North Hungarian Bay and open marine waters, which allowed the transmission of tidal waves was the outlet towards the East Slovakian Basin in the northeast. The presence of tide-influenced deposits in the North Hungarian Bay implies that tidal waves entered the Eastern Paratethys from the east through a wide passage. examples of Lower Miocene tide-influenced deposits in the Mediterranean and Paratethian regions are reported from different periods. In these cases amplification of tidal motions in various embayments and straits also occurred because of the local basin morphology. It is demonstrated that significant palaeogeographic changes during the Early Miocene resulted in changes of current pathways and related shifts of loci of tide-influenced deposition.