The Upper Turonian of the Bohemian Cretaceous Basin (Czech Republic) exemplified by the عpohlavy working quarry: integrated stratigraphy and palaeoceanography of a gateway to the Tethys

The north Bohemian Cretaceous (Bohemian Cretaceous Basin; Czech Republic) is located between the northern temperate areas and the Tethys. As a gateway to the Tethys, lithology, fauna and integrated stratigraphy (litho-, bio-, event, sequence, stable isotope stratigraphy) of the Upper Turonian succession in the Úpohlavy working quarry are described. Due to a large hiatus, the δ13C curve cannot be used for stratigraphic purposes at the base of the section. Up-section, the curve exhibits the well-known middle Upper Turonian positive excursion. Biostratigraphic and sequence stratigraphic subdivisions permit good correlation with other European Cretaceous basins. The inoceramid bivalve assemblage enables correlation with the US Western Interior. Palaeoceanographically, a positive peak in the δ18O curve above the hiatus indicates the upper part of the Late Turonian cooling event observed in other areas. The cooling was accompanied by a southward shift of a cool/temperate oceanic biosedimentary system, expressed by the sudden turnover from siliciclastic towards pelagic carbonate deposition. It is associated with the establishment of presumed oligotrophic conditions in the immediate vicinity of the West Sudetic Island, as indicated by the sudden decrease of macrofaunal abundance and diversity.