Belemnites and calcareou nannofossils from the North Bohemia reveal prolonged Jurassic sedimentation in Central Europe
Abstrakt
Belemnites from North Bohemia were previously, in most cases, assigned exclusively to the Upper Jurassic (Oxfordian - Kimmeridgian). Tectonically and fragmentarily preserved Jurassic strata along the Lausitian Fault were divided into the non-fossiliferous Callovian Brtníky Formation and fossiliferous Oxfordian and Kimmeridgian strata (Doubice Formation).
We have applied a detailed stratigraphic framework dealing with previously published data based on the systematic investigation of preserved belemnite rostra and calcareous nannoplankton. Macro- and microfaunal character points to possible continuous sedimentation with frequent gaps (linked probably to eustatic cycles).
Therefore, the historical lithostratigraphic regional division (Brtníky and Doubice formations based on a similar lithological character) is probably not relevant. Belemnites were classified at the generic and species levels (including at least five genera with at least eight species).
The stratigraphic distribution of the studied belemnites and calcareous nannofossils surprisingly showed ranges from the Bajocian to Tithonian, based on belemnites, ammonites and calcareous nannoplankton. Megateuthidid belemnites (Megateuthis suevica and Megateuthis cf.
Megateuthis elliptica) indicate the earliest known faunal components within the Central European Jurassic (Bohemian Massif). Belemnites clearly show the prevailing Tethyan (Belemnopsis fauna) and partly also Boreal (Cylindroteuthis cf.
Cylindroteuthis puzosiana) provenances. Our results provided the first comprehensive description of the Jurassic belemnite fauna from Northern Bohemia and Saxony.
Our approach significantly fills a gap in stratigraphical, palaeoenvironmental, and palaeobiogeographical interpretations of Jurassic strata within Central Europe based on belemnites.