The low C~13C values observed in beds with high TOC and high hydrogen index in the Toarcian oil shales of the 'Posidonienschiefer' (Lower Jurassic) correlate with palynomorph assemblages composed largely by prasinophyte phycomata and sphaeroidal, coccal palynomorphs of ambiguous affinity ('sphaericals'). The macerals of the same beds are dominated by lamalginite and bituminite. The liptodetrinite content is very variable. Vitrinite, inertinite and sporinite maccrals are rare. This correlation is consistent with the model proposed by Riegel et al. for the 'Posidonienschiefcr' of northwestern Germany.The accumulation and preservation of the organic matter were favoured by a density stratification of the water column caused by the influx of low-salinity water. The paleogeographic setting and the affinity of dinocyst assemblages in the Proto-Arctic and in W Europe during Pliensbachian/Toarcian times suggest a high-latitude origin of this lowsalinity water.Hydrogen indices obtained from Rock-Eval analyses indicate Type-II kerogen for most Of the 'Posidonienschiefer' oil shale. Reflectance values of vitrinite and bitumen in oil shales are significantly suppressed by the presence of high amounts of liptinite.The maturity of the organic matter determined by vitrinite reflectance and by Rock-Eval pyrolysis corresponds to the start of the oil window.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.