Jurassic continental deposits in the sections of the Irkutsk Coal Basin stratoregion

Resumo

This paper presents bed-by-bed description and paleofloristic characterization (on the basis of plant macroremains) of the Jurassic continental deposits of the Irkutsk Coal Basin, in the sections of the stratotype region where the lithostrata now widely used for the geological mapping works were established for the first time. The characteristics of these units are refined along with their age and occurrences. Newly obtained taphofloras are comparatively analyzed and established to be synchronous. The spatial distribution of Jurassic deposits from different outcrops is correlated with sections of the reference boreholes. Two successive phytostratigraphic assemblages, Cheremkhovo and Prisayan, are recognized. These assemblages are correlated based on the taxonomic composition of the dominant plant groups, with the assemblages of the end of the Early Jurassic and the beginning of the Middle Jurassic of Western Siberia, which are dated using coastal marine fauna.