Lower and Middle Jurassic foraminiferal and ostracod biostratigraphy of the eastern Barents Sea and correlation with northern Siberia

The Barents Sea shelf and adjacent areas comprise one of the important petroleum-bearing provinces of the world. During the last three decades, these areas have received considerable interest in the exploration for petroleum, resulting in the discovery of several new gas and oil fields. This has necessitated large-scale geological mapping and evaluation studies based on detailed biostratigraphy and high-resolution stratigraphy. Apparently synchronous microfauna assemblages of Lower and Middle Jurassic age are characterized by closely similar taxonomic composition in both the Barents Sea shelf and northeastern Siberia, allowing the recognition of the Siberian zonal successions in Barents Sea region. Detailed biostratigraphic analysis of foraminiferal and ostracod zonal subdivisions, together with lithostratigraphic data, have provided the basis for a more detailed determination of the stratigraphic position and extent of lithostratigraphic units and seismic sequence in the Barents Sea shelf. The results show that the Lower and Middle Jurassic sections of Barents Sea shelf and northern Siberia have a very similar lithostratigraphic structure. Taking into consideration the microbiotic similarity and lithostratigraphic development of these regions, a high degree of regional homogenity of depositional conditions can be assumed in the Early and Middle Jurassic.