Lithostratigraphy and Sedimentation Conditions of the Bazhenov Formation (Western Siberia) in the Central, Southeastern, and Northern Regions of Its Occurrence

• Published in: Stratigraphy and geological correlation 2022-10, Vol.30 (5), p.334-359
• Main Authors: Eder, V. G., Ryzhkova, S. V., Dzyuba, O. S., Zamirailova, A. G.
• Format: Article
• Language: English
• Subjects: Accumulation; Archaeology; Carbonates; Clay; Coccoliths; Cretaceous; Earth and Environmental Science; Earth Sciences; Geophysics/Geodesy; Historical Geology; Jurassic; Lithology; Organic matter; Principles; Sea level; Sea level changes; Sedimentary basins; Sedimentary rocks; Sedimentation; Sedimentation & deposition; Sedimentology; Sediments; Shale; Siliceous sediments; Structural Geology
• ISSN: 0869-5938; 1555-6263
• DOI: 10.1134/S0869593822050021

— The sections of the boundary Jurassic–Cretaceous black shale sediments (Bazhenov Formation) of the West Siberian sedimentary basin in conditional Central, Southeastern, and Northern regions are compared on the basis of a complex lithological-geochemical study, as well as geophysical and paleontological data. The studies are conducted using a common classification scheme of rocks and common principles of recognition of members in the structure of the formation. The elaborated sedimentation models reflect the spatiotemporal principles of the origination of the Bazhenov Formation depending on the features of paleotopography, proximity to the provenances, climatic fluctuations, and changes in sea level. The Central region was mostly characterized by biogenic siliceous sedimentation (radiolarian or similar sediments) during the entire Volgian Stage (locally, to the beginning of the Ryazanian Stage) and by carbonate-siliceous sedimentation (coccolith-rich sediments) from the end of the Volgian Stage to the beginning of the early Valanginian, which was favorable for the accumulation of a significant amount of organic matter. The accumulation of carbonate-siliceous sediments finished by the middle of the Ryazanian Stage within the Khantei Hemianteclise and the southeastern part of the South Nadym Megamonoclise of the Central region. In the Southeastern region, the formation of organic-rich sediments terminated at the stage of accumulation of biogenic-siliceous silts and, from the beginning of the Ryazanian Stage, was followed by sedimentation of organic-poor clays of the Megion and Kulomzino formations. The Northern region was characterized by the accumulation of relatively organic-poor siliceous-argillaceous sediments with a dominant terrigenous (over biogenic) component by means of more intense gain of clay material to this zone of the paleobasin. The sedimentation of the Bazhenov Formation here was probably terminated in the first half of the Ryazanian Stage.