Sedymentacja utworów miocenu we wschodniej części zapadliska przedkarpackiego

Abstract

Miocene deposition in the eastern part of the Carpathian Foredeep in Poland.Summary. Results of new biostratigraphical investigations correlated with nannoplankton zones permit to suggest that deposits which are filling the eastern, Polish part of the Carpathian Foredeep Basin include also the late Sarmatian and Panonian deposits. The filling of eastern parts of the Carpathian Foredeep, as in most foredeep basins, took place in two main stages; (1) underfilled flysch stage - lasting from the early Badenian to the lower part of late Badenian (Moravian–Wieliczian) and (2) overfilled molasse stage — lasting from upper part of the late Badenian to Panonian (Kosovian–Meotian). Classically, this flysch to molasse transition is interpreted as a record of the migration of the thrust wedge and foreland basin over the hinge line of the inherited passive margin. Also, the Badenian and Sarmatian successions are characterised by very diverse facies, which were deposited in various depositional environments. A detailed sedimentological analysis of cores, together with well log analysis, and seismic sections permitted to fit the stratigraphic column into a sequence stratigraphic framework. Within this framework, the Badenian and Sarmatian successions are interpreted to have been deposited within 3 third-order depositional sequences: the first two in the Badenian (not recognised in seismic scale), and the third during the Sarmatian, which consists of 4 fourth order sequences (Dziadzio, 1999, 2000), with total thickness of 800 to over 3000 m. The M3 boundary is interpreted as a flooding surface within the fourth order, oldest Sarmatian depositional sequence. The M2 boundary corresponds to the boundary between two foraminiferal zones Anomalinoides dividens and Varidentella reussi, within the Sarmatian succession, which lies in the upper part of the second Sarmatian sequences, near the maximum flooding surface, in late phase of highstand sea level. The M1 boundary is interpreted as a transgressive surface within the third Sarmatian sequence. The boundary M0 marks transgressive surface within the fourth Sarmatian sequence and also is a stratigraphical boundary between two youngest foraminiferal zones Velapertina reussi and Porosononion granosum, and marks a border between the Wolhynian and Bessarabian stages.