A Model of a Shear Landslide Wedge with Subsequent Hydraulic Rupture as an Explanation for the Formation of an Anomalous Section of the Bazhenov Formation in the North of Western Siberia. Part 2. Description of the Mesostructural Complexes in the Core and the Model of the Anomalous Formation of the Section

A new anomalous section of the Bazhenov Formation has been described on the territory of the Urengoy deposit in the northern part of Western Siberia. This article describes mesostructural complexes in the core, which have served as a basis for the suggestion of a new model for the formation of the anomalous section of the Bazhenov Formation. It has been found that the mesostructural complexes were formed at different landslide stages and during the movement of the landslide body along the uneven surface of the detachment. The main role in the formation of large injection “sand veins” in the studied section was probably played by the landslide-induced grain flow from the coastal shallow water area. The penetration of its sandy material into the rocks of the Bazhenov Formation and, to a lesser extent, the Achimov Formation was determined by the energy of a hydraulic shock and hydraulic fracturing along layer-by-layer and secant fractures.