Paleogeographic and litho-facial conditions of meso-cenozoic sediment formation of the Anadyr depression

Background. The Anadyr depression has a marginal structure. It comprises four sub-regional elements. Disjunctive dislocations are widely developed within the area. Aim. To reconstruct the paleogeographic and litho-facies conditions of the formation of the Meso-Cenozoic sediments of the Anadyr depression. The reconstruction was performed by evaluating the initial data and developing paleogeographic and litho-facies maps. Data on the conditions of sediment formation in the study area, rich in hydrocarbon and mineral deposits, is essential from a practical standpoint. Materials and methods. Paleogeographic reconstructions of the Anadyr depression were performed based on an analysis of the sediment thickness and litho-facies composition of the relevant age. To build litho-facies maps, we used the data on the material composition of the Bering Sea sedimentary cover and adjacent areas, including well-drilling data, outcropping descriptions, thickness gradient analysis, seismic study results, etc. Results. In the course of the work, sedimentary environment maps were created. Litho-facies maps were developed for all four main sedimentary complexes of the Anadyr depression. Based on the generalised geological data and paleoreconstructions, we constructed forecasting schemes of the distribution of barrier formations in the study area. Conclusions. It was found that the formation of the sedimentary cover of the Anadyr depression took place mainly in shallow-water sedimentary environments. In addition, the depths of paleobasins did not overpass the internal relatively shallow marine shelf. Based on the analysis, two most probable reservoirs were selected. Regional fluid and potential seals were characterised.