Publisher © Czech Geological Survey, ISSN: 2336-5757 (online), 0514-8057 (print)
Diachronic occurrence of Marthasterites furcatus in the Turonian sediments of the Bohemian Cretaceous Basin and Western Carpathians, Czech Republic
Abstract
The diachronic occurrence of calcareous nannofossil species Marthasterites furcatus is evident in the Turonian sediments both in the Bohemian Cretaceous Basin and Western Carpathians. In the Outer group of nappes of Western Carpathians, the first occurrence (FO) of M. furcatus is recorded in two levels: 1. Lower Turonian (UC6b and UC7 zones) in association with Eprolithus moratus and Quadrum gartneri in the Silesian Unit, 2. Upper Turonian (UC9b Zone) in association with Lithastrinus septenarius and Zeugrhabdothus biperforatus in the Ždánice-Subsilesian Unit. Concerning the Bohemian Cretaceous Basin, FO M. furcatus was recognized during Upper Turonian. In the western part of basin it was found approximately with FO Z. biperforatus in the lower Upper Turonian, in the lowermost part of Teplice Formation but in the eastern part of basin in the uppermost Turonian, few metres bellow the Didymotis II event, Turonian-Coniacian boundary respectively. M. furcatus is not suitable for the biostratigraphic conclusions not only for the diachronic occurrence reason but also for its scarce and not continuous presence in the Turonian deposits. Common and continuous presence of M. furcatus both in the Bohemian Cretaceous Basin and Ždánice-Subsilesian Unit, Western Carpathians was recorded in the interval uppermost Turonian-Lower Coniacian. The diachronic FO M. furcatus can be used for the paleogeographic interpretations. Its presense in the Lower Turonian of Silesian Unit gives evidence for the significant influence by Boreal province from North in this depositional area.
