Sedimentary conditions of the Abalak formation and Vogulkinskaya strata on the area of Kamennaya summit (Krasnoleninsky arch, Western Siberia)

Abstract

As part of this work, various sedimentation environments were identified in the Middle-Late Jurassic (J2k–J3v1) on the territory of the Krasnoleninsky arch in Western Siberia. The heterogeneity of the seabed topography and the presence of islands formed by protrusions of the pre-Jurassic basement led to the formation of the Vogulka strata as a result of the removal of clastic material from the land. At the same time, far from the islands, in relatively calm shallow environments, clayey and glauconite-clayey sediments of the Abalak Formation accumulated. Gravelites and sandstones of the Vogulka strata were formed unevenly. The greatest thickness of these deposits is observed to the west of the central upland. The difference in the thickness of clastic strata on the western and eastern slopes could probably be caused by the specific horseshoe shape of the island and the absence of active currents on the western part of the slope, as well as its greater steepness. The upper member of the Vogulka strata, composed of detrital limestones, is extremely thin (no more than 1 m), and contains numerous unconformities. Probably, these traces of erosion can be indirect evidence of the influence of the Late Oxford regression on the structure of the section, which was previously noted in adjacent territories.