Basement Characterisation by Regional Isostatic Methods in the Barents Sea

We study the tectonic setting of the greater Barents Sea region by investigating the isostatic state and the gravity field. Forward gravity modelling utilizing available information from seismics and boreholes show an apparent shift between the level of observed and modelled gravity anomalies. The difference cannot be solely explained by crustal densities and is changing between the Western and Eastern Barents and the Kara Seas. Local isostatic calculations show that the present crustal thickness in the Eastern Barents Sea is larger than expected. Despite the large sedimentary basins in the Eastern Barents Sea of up to 20 km thickness, the average Moho depth is >35 km. To compensate the thick crust, high-density material in the lithospheric mantle is needed in agreement with the gravity modelling. Taking into account the isostatic compensated mantle densities, the gravity field of the Eastern Barents Sea Region can be modelled generally well with local changes in crustal densities. The results indicate that the basins of the Western Barents Sea are mainly affected by rifting, while the Eastern Barents Sea basins seem to be intracratonic basins, and the Zemlya basins are flexural basins related to the mountain chain of Novaya Zemlya.