Geochemical characterisation of belemnite rostra from North-West Bohemia (Upper Cenomanian) - A contribution to palaeoenvironmental interpretation of a peri-Tethyan shelf
Abstrakt
The Bohemian Cretaceous Basin (BCB), the largest intracontinental basin within the Bohemian Massif extends across Saxony, Bohemia, Moravia and Silesia (Čech 2011). The preserved rocks within the BCB are possibly from the Lower (?Albian) to Upper Cretaceous (Cenomanian to Santonian).
We present studied rock sequences herein belonging to Oceanic Anoxic Event II (OAE II). High-resolution climate records reveal considerable changes in temperature, carbon cycling, and ocean chemistry during this climatic perturbation.
A cooling phase is preserved within the English Chalk based on an invasive Boreal fauna and bulk oxygen-isotope excursions registered during the early stages of OAE II. Here we describe the occurrence and geochemical characteristics of the belemnite species Praeactinocamax plenus (Blainville, 1827) within the BCB.
This Upper Cenomanian representative of fauna from the Metoicoceras geslinianum Zone is documented and morphologically well described. Its occurrence indicates the change of the palaeoenvironmental aspects, which is called Plenus Cold Event (PCE).
An abundance of this species is low except the so-called Plenus-beds (calcareous siltstones). P. plenus is also characteristic in limestones, marl/limestone alternations, and had preference of shallower water environments.
A phenomenon known as the Plenus Cold Event has tentatively been correlated with climatic shifts worldwide.