Využití izotopů ve stratigrafii křídy slezské jednotky.

Abstract

The thesis deals with Cretaceous black shales from the Silesian Unit in the Outer Western Carphatians. The total organic carbon (TOC) content and carbon and oxygen isotopes in carboniferous and organic matter were studied in selected profiles. Also done was quantitative analyses of organic matter (palynofacies) contain in the studied sediments. Analyses were done on four profiles: Skalice, Pindula, Bystrý potok and Němetice. An increased content of total organic carbon was observed in upper Valanginian (up to 5.8 %), upper Aptian (up to 3.7 %), the uppermost Albian (up to 3.3 %) and lower Cenomanian (up to 3.6 %). Carbon and oxygen isotopes (δ13C, δ18O) were studied on the Skalice profile in the stratigraphic range of Valanginian and on the Němetice profile in the stratigraphic range Cenomanian/Turonian. On profiles Pindula (Barremian – Albian) and Bystrý potok (Albian – Campanian) it was only possible to study C isotopes in organic matter. The analyses results are correlated with similar records cited in literature. The changes in the isotopic rates and the high content of the total organic carbon indicate the presence of Oceanic Anoxic Events (OAE) at the studied locations. Based on geochemical analyses and their correlation with paleontological data, it is possible to assume the presence of OAE in the upper Valanginian, the uppermost Aptian, the upper Albian, the lower Cenomanian and around the Santonian/Campanian.