Depositional systems and paleogeography of Upper Cretaceous-Paleogene deep-sea flysch deposits of the Magura Basin (Western Carpathians)

摘要

The Outer Western Carpathians are part of the Alpine-Himalayan orogenic belt, and they are formed mostly by the Upper Cretaceous and Paleogene deep-sea "flysch" sequences. Orava region (northern Slovakia), situated in the central part of the Magura Nappe, has an important position for the solution of the geological structure and development of the Magura Nappe. At the beginning of the research, determination of the sedimentary sequences of the Magura Nappe and the fundamental lithotypes and lithofacies was required. A total of 1164 paleocurrent measurements were measured and assigned to lithotypes and lithostratigraphic units obtained during the detailed sedimentological study. The main purpose of the research was the interpretation of the filling history and tectonic activity of the Magura Basin. The results of the detailed sedimentological study were integrated with published data from surrounding regions. Presented palinspastic maps propose a reconstruction of the filling history and tectonic activity in chronological order during the Upper Cretaceous to Oligocene. Maps focus in detail on the western part of the Magura Basin, but they display its surroundings as well. The sedimentary record reflects the activity and gradual shifting of the Western Carpathian accretionary wedge to the north, the uplift of source areas, and the changes in the sea level of the Magura Basin. The paleocurrent analyses joined with the sedimentological and petrographic research allowed to reconstruct the paleogeographic properties of the northern sources of detritic material (Hostyn, Fore-Magura and Silesian Ridges), of the southern source of the material (Western Carpathians accretionary wedge) and of intrabasinal sources as well (Szczawina and Southern-Magura Ridges). We propose a discussion about the character of filling history, defining and position of the source areas and about Hostyn Ridge defined here.