Crustal structure of the North Svalbard margin: Continental breakup and Eurasia Basin opening

Abstract

Continental breakup at the North Svalbard margin and the northern Barents Sea during the Paleogene led to the opening of the oceanic Eurasia Basin. However, the mechanisms behind this rift-to-drift evolution remain unclear. Here, we present seven crustal transects (CT1–7) integrating 2D forward modelling of potential field data and constrained by structural interpretation of multichannel seismic reflection profiles. These transects extend from the continental regions of North Svalbard to the oceanic domain in southwest Eurasia Basin. The Yermak Plateau comprises two juxtaposed tectono-magmatic blocks: the Northeast Yermak Plateau, linked to pre- or early Eurekan settings, and the Southwest Yermak Plateau, formed by shearing and oblique extension along the West Svalbard margin. Broadly, the North Svalbard margin is divided into three segments: (1) Northwest Spitsbergen-Southwest Yermak Plateau, (2) Northeast Spitsbergen-Northwest Kvitøya, and (3) Northeast Kvitøya-North Barents. Segmentation follows inherited north-northwest trending weak zones, guiding Paleogene multi-phase oblique rifting and formation of the Sophia Basin, underlain by thinned, high-density metamorphic crust. The results indicate a rift-shear breakup mode with exhumation of continental lower crust and/or serpentinized subcontinental mantle blocks within the continent-ocean transition (COT) that precedes seafloor spreading which started at ca. 53 Ma during magnetic chron C24. The continental breakup processes that led to margin segmentation reflect the interplay between inherited basement fabrics and plate opening directions of the Eurasia Basin region.