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. The total and tectonic subsidence were estimated, which made 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 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 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 the transitional crust. Whether continental crust from adjacent areas of the Baltic shield (approximately 40 km) is accepted as undeformed, according to seismic data the crust thinning was approximately 2,5 that is close to thinning estimated from McKenzie model. The comparison of the obtained data with theoretical models of the passive margins subsidence indicates that the rifting and the 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 Late Devonian, shape of the total and tectonic subsidence show that the most intense deposition occurred in Permian and Triassic. This contradiction gives evidence for interpretation that after the Late Devonian rifting, a deep-water basin was formed and filled in only in Permian. Water depth estimated from interpretation of sedimentological and paleontological data varies from 1,0 to 3,5 km. According to shape of the tectonic subsidence curve, during Carboniferous water depth was close to 3,5 km.