New data on the stratigraphy and depositional environment of the Jurassic-Cretaceous boundary sediments of the northwestern part of the Yenisei-Khatanga trough

Abstract

Research subject. Boundary Jurassic-Cretaceous sediments of the western part of the Yenisei-Khatanga Regional Trough. Materials and methods. The main correlation tools were seismostratigraphic, logging, and biostratigraphic methods. Litho- and biofacies methods were used to reconstruct the development conditions of the Yanovstan Formation and the NKh group of the Ryazanian Stage reservoirs. Results. The composition of macro- and microfauna complexes was defined, analogues of the ammonite and foraminiferal zones of the Upper Volgian substage and the Ryazanian stage of Siberia were established. The structure of the Upper Jurassic and Ryazanian complexes of the western part of the Yenisei-Khatanga Regional Trough was detailed. Conclusions were made about the formation conditions of the Volgian and Ryazanian deposits. Conclusions. The sediments were found to have been formed in a sea basin with stable salinity and low water energy, in relatively deep-water conditions. Mixed turbidite systems with multipoint supply sources were identified, in which the terrigenous material was supplied from southeast to northwest.