Biostratigraphy and lithological features of Carboniferous Urmugteyul Formation (Orkhon Trough, Northern Mongolia)
The results of a biostratigraphic and lithological studies of the terrigenous Carboniferous Urmugteyul Formation in the stratotype area (left bank of the Sharyn-Gol River, Orkhon Trough) are presented in this research paper. Four members are distinguished in the composition of the formation; the first three members are assigned to the Lower Urmugteyul Subformation, the fourth is to the Upper Urmugteyul Subformation. The first palynological studies made it possible to limit the accumulation time of the Lower Urmugteyul Subformation to Late Tournaisian, and the Upper Urmugteyul Subformation to Late Visean. The nature of the structure and lithological features of the section, considered as part of two terrigenous facies associations, as well as the paleontological characteristics and analysis of palynofacies, indicate that the accumulation of the Lower Urmugteyul Subformation occurred in the alluvial-delta plain settings, and the Upper Urmugteyul Subformation is in the shallow shelf basin.