The Tectonic Subsidence Evolution of the Southern Part of the East Barents Sedimentary Basin

Abstract

The history of the subsidence of the southern part of the East Barents Sedimentary Basin was reconstructed based on the interpretation of 6 seismic profiles along with data from rare deep wells. Total and tectonic subsidence were estimated, which made it possible to determine the magnitude of the lithosphere stretching factor (β) throughout the history of the region. The values of the stretching factor (β) range from 2.5–3.0 for areas with the highest thickness of sediments in the central part of the basin, to 1.25–1.66 for areas on the margins of the basin with the lowest thickness of sediments. Close values of the stretching factor (β) characterize the Atlantic coast of North America in the area with predominant distribution of transitional crust. If continental crust from adjacent areas of the Baltic Shield (approximately 40 km) is accepted as undeformed, then according to seismic data, the crust thinning was approximately 2.5, which is close to thinning estimated from the McKenzie model. Comparison of the obtained data with theoretical models of passive margins subsidence indicates that rifting and transition to the stage of sedimentary basin formation occurred in accordance with the McKenzie uniform stretching model. Although available geological data show that the most intense rifting occurred in the Late Devonian, the shape of the total and tectonic subsidence show that the most intense deposition occurred in the Permian and Triassic. This contradiction gives evidence for the interpretation that after the Late Devonian rifting, a deep-water basin was formed which filled in only in the Permian. Water depth estimated from interpretation of sedimentological and paleontological data varies from 1.0 to 3.5 km. According to the shape of the tectonic subsidence curve, during the Carboniferous, water depth was close to 3.5 km.