Sequence Stratigraphy of the Volhynian (Late Middle Miocene) Deposits from the North Sector of Eastern Carpathian Foredeep

An exposed sedimentary succession, ca 115 m of 1000 m, from the Eastern Carpathian foredeep was for the first time analysed using facies analysis and scale and time inde-pendent sequence stratigraphy methods to reveal the depositional environment and its cyclic sedimentation. The outcropping deposits, dated on the basis of molluscs, forami-nifera, and ostracods are uppermost Volhynian (late Serravalian). The three recurrent facies associations we distinguished indicate a high energy shoreface – transition to offshore environment, episodically affected by storms. Five decametre thick high fre-quency sequences (HFS1–5), at most of 4th rank, bounded by maximum regressive sur-faces, were defined in the studied interval. The maximum thickness of Volhynian (12.65 – 12 Ma) deposits in the area, known both from well sites and outcrops, allowed to estimate the sedimentation rate at ca 1.5 mm/yr. The fossil content shows that entire sedimentary succession deposited in very shallow to shallow water during all Volhyn-ian. The time interval we studied was ca 75 kyr, so that average time of a HFS is ca 15 kyr. At this scale, considering that both high subsidence and Eastern Paratethys sea-level rise added to accommodation, the sediment supply must have been responsi-ble of cyclic nature of sedimentation, which, in turn, must have been controlled by precession climatic changes in the source area. The estimated time of a HFS is smaller than a precession cycle, but better dating might support or infirm this hypothesis.