3-D density and magnetic crustal characterization of the southwestern Barents Shelf: implications for the offshore prolongation of the Norwegian Caledonides

Abstract

SUMMARY The presented study focuses on understanding the Barents Sea tectonic evolution. 3-D joint gravity and magnetic modelling of the southwestern Barents Shelf is based on a wealth of offshore seismic and onshore geological information. It allows characterizing the crust with respect to its density and magnetic properties. The main outcomes of the study are (1) new information on key geological interfaces through the production of a new top basement map and upper/lower crustal boundary and Moho maps. In addition, (2) a crustal units map based on density and magnetic properties distribution is proposed and helps understanding of the tectonic evolution of the region. Finally, (3) the study has highlighted disparate basin evolution east and west of the Loppa high. To the east of the Loppa High, a combination of Timanian and Caledonian faults and weakness zones may have played an important role in the evolution of the Mesozoic and Cenozoic sedimentary basins. To the west of the Loppa High, the basinal evolution seems mostly controlled by the reactivated Caledonian suture. The integration of new interpretations leads to a new structural conception of the Caledonian orogen with a unique Caledonide branch propagating towards the north and a confirmation of Caledonian nappes emplaced asymmetrically in the western Barents Sea. The proposed geometry is interpreted as linked to the palaeogeography of the Baltican Plate.