Bazhenov horizon of Siberia (Tithonian – Lower Berriasian): tectonic and hydrodynamic conditions of sedimentation

Abstract

The new model of the sedimentation of the Bazhenov Formation, on which black shale accumulated on relative elevation – a shallow-marine hilly plateau, agrees well with the results of a general paleogeographic analysis of the Bazhenov horizon of Siberia. In addition to the favorable conditions for the accumulation and fossilization of organic matter, the most important conditions for the formation of a unique Bazhenov suite are the multiplicity of nutrient sources, their constant flow, and the capture of almost all the terrigenous material in the flow basins of the Ural-Khatanga strike-slip. Judging by the presence of incisions and the distribution of facies in the system of strke-slip basins, a sea current from the Arctic Ocean operated on the territory of the YeniseiKhatanga trough. Periodic changes of the Arctic runoff were probably synchronous episodes of tectonic activation in the divergent shear zone. Rising sea levels led to flooding of the hilly‑lake South-Taimyr coastal basin and increasing the flow of sedimentary material from it. During the transgressions, nutrients were removed from flooded plains of South Taimyr. At the same time, the transgressions “locked” the flow from the Vilyui alluvial-lake basin. During regressions, on the contrary, the runoff of sedimentary material and biophilic elements from Vilyui sharply increased.