Main structure formation units in sedimentary basins of Russia’s eastern arctic seas: stages and conditions of formation

In order to reach this paper’s objectives aimed at studying hydrocarbon systems in the sedimentary basins within the East Arctic Seas, we have applied a specialized step-by-step technique of paleotectonic and geodynamic analyses. The initial steps of this procedure involve analyzing the present-day structural geometries of the main unconformities with a view to determining key tectonic stages in the evolution of the sedimentary succession. Specific aspects of vertical movement at each stage are also examined. This is followed by analyzing thickness maps of sedimentary formations between the main unconformities, identifying basin boundaries and areas of persistent downwarping. Next, depositional rates for each key stage of evolution are calculated and analyzed. Based on the studies of geodynamic conditions, we have conducted geodynamic zonation, and identified and described six structure formation units within the examined Eastern Arctic offshore areas: a unit of intermontane and foredeep depressions, an intracontinental unit, units resulting from shear and extension near plate boundaries, compression near plate boundaries, rift-driven extension, and a unit of overlying passive margins. A total of four structural levels have been identified in the Laptev Sea area (Cretaceous, Paleocene–Eocene, Oligocene and Miocene–Quaternary) and three structural levels in the East Siberian and Chukchi Seas (Cretaceous, Paleocene–Eocene and Oligocene–Quaternary).