Abstract This book is the final product of the Circum-Arctic Lithosphere Evolution (CALE) project. The project’s ultimate goal is to link the onshore and offshore geology in order to develop a self-consistent set of constraints for the opening of the Amerasia Basin. The circum-Arctic is divided into seven regions, each with its own research team; the teams included geophysicists and geologists working together to integrate geological and geophysical data, from onshore to offshore. This work is summarized in the 18 papers contained in this volume.

Abstract We perform an integrated analysis of magnetic anomalies, multichannel seismic and wide-angle seismic data across an Early Cretaceous continental large igneous province in the northern Barents Sea region. Our data show that the high-frequency and high-amplitude magnetic anomalies in this region are spatially correlated with dykes and sills observed onshore. The dykes are grouped into two conjugate swarms striking oblique to the northern Barents Sea passive margin in the regions of eastern Svalbard and Franz Josef Land, respectively. The multichannel seismic data east of Svalbard and south of Franz Josef Land indicate the presence of sills at different stratigraphic levels. The most abundant population of sills is observed in the Triassic successions of the East Barents Sea Basin. We observe near-vertical seismic column-like anomalies that cut across the entire sedimentary cover. We interpret these structures as magmatic feeder channels or dykes. In addition, the compressional seismic velocity model locally indicates near-vertical, positive finger-shaped velocity anomalies (10–15 km wide) that extend to mid-crustal depths (15–20 km) and possibly deeper. The crustal structure does not include magmatic underplating and shows no regional crustal thinning, suggesting a localized (dyking, channelized flow) rather than a pervasive mode of magma emplacement. We suggest that most of the crustal extension was taken up by brittle–plastic dilatation in shear bands. We interpret the geometry of dykes in the horizontal plane in terms of the palaeo-stress regime using a model of a thick elastoplastic plate containing a circular hole (at the plume location) and subject to combined pure shear and pressure loads. The geometry of dykes in the northern Barents Sea and Arctic Canada can be predicted by the pattern of dilatant plastic shear bands obtained in our numerical experiments assuming boundary conditions consistent with a combination of extension in the Amerasia Basin sub-parallel to the northern Barents Sea margin and a mild compression nearly orthogonal to the margin. The approach has implications for palaeo-stress analysis using the geometry of dyke swarms. Supplementary material: Details on traveltime tomography model: Resolution tests, traveltime information and ray coverage are available at https://doi.org/10.6084/m9.figshare.c.3783542

Abstract: Compound-specific isotope analysis (CSIA) of individual organic compounds is a powerful but underutilized tool in petroleum exploration. When integrated with other organic geochemical methodologies it can provide evidence of fluid histories including source, maturity, charge history and reservoir processes that can support field development planning and exploration efforts. The purpose of this chapter is to provide a review of the methodologies used for generating carbon and hydrogen isotope data for mid- and high-molecular-weight n -alkanes. We discuss the factors that control stable carbon and hydrogen isotope compositions of n -alkanes and related compounds in sedimentary and petroleum systems and review current and future applications of this methodology for petroleum exploration. We discuss basin-specific case studies that demonstrate the usefulness of CSIA either when addressing particular aspects of petroleum exploration (e.g. charge evaluation, source rock–oil correlation, and investigation of maturity and in-reservoir processes) or when this technique is used to corroborate interpretations from integrated petroleum systems analysis, providing unique insights which may not be revealed when using other methods. CSIA of n -alkanes and related n -alkyl structures can provide independent data to strengthen petroleum systems concepts from generation and expulsion of fluids from source rock, to charge history, connectivity, and in-reservoir processes.

Abstract The Greenland and Svalbard Caledonides make up an important part of the Palaeozoic Caledonian orogen, and preserve a complex history of Palaeoproterozoic arc accretion, Proterozoic to Palaeozoic sedimentation within various basins and extensive magmatism, metamorphism and deformation during the Caledonian orogeny. In this summary, the current understanding of the structure and lithological content of the Greenland and Svalbard Caledonides is first reviewed, and open questions are highlighted. The Greenland Caledonides are divided into three different segments, and the term terrane is abandoned for the Svalbard Caledonides. Then, other Caledonian fragments in the Arctic region are discussed, including Bjørnøya, Pearya and Cordilleran terranes and parts of the Barents Shelf. Finally, a regional synthesis covering the geological evolution of the Greenland and Svalbard Caledonides from the Palaeoproterozoic to the end of the Caledonian orogeny is presented and controversial issues and open questions are discussed.