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.

Sequence stratigraphy and palaeogeography of the Upper Jurassic and Lower Cretaceous in the Eastern Barents Sea

“…One of the common features for both basins is the presence of the clastic wedge deposited prior to the clinoform packages: the Sequence J3 of the Tithonian–Berriasian in the Barents Sea Basin and Yanovstanov Fm of the Kimmeridgian–Berriasian in the Western Siberia Basin (Figure 28). The Yanovstanov Fm is recognised in the north‐eastern part of the West Siberia Basin and comprises a clastic wedge up to 700 m thick (Gurary, 2004; Stafeev et al., 2019). The clastic wedge of the Yanovstanov Fm marks the beginning of the deep basin infill caused by the uplift of the source area most likely in the Verkhoyansk fold belt and Siberian Platform (Stafeev et al., 2019).…”

“…The Yanovstanov Fm is recognised in the north‐eastern part of the West Siberia Basin and comprises a clastic wedge up to 700 m thick (Gurary, 2004; Stafeev et al., 2019). The clastic wedge of the Yanovstanov Fm marks the beginning of the deep basin infill caused by the uplift of the source area most likely in the Verkhoyansk fold belt and Siberian Platform (Stafeev et al., 2019). The J3 clastic wedge in the South Barents Sea Basin represents the same tectonic event and most likely connected to the Arctic Ocean opening, however, it is younger and might indicate a time lag in the response to the events.…”

“…Yanovstanov Fm is interpreted as a clastic wedge prograded from Siberian Craton. Lower Cretaceous clinoforms prograded westwards and downlap the black shales of Bazhenov Fm (modified after Stafeev et al., 2019). Vertical exaggeration of the seismic profile ×40.…”