Dolerites of Svalbard, north-west Barents Sea Shelf: age, tectonic setting and significance for geotectonic interpretation of the High-Arctic Large Igneous Province

Abstract

The dolerites of Svalbard are mineralogically and geochemically homogeneous with geochemical features typical of continental within-plate tholeiites. Their geochemistry is similar to tholeiites belonging to a bimodal suite defined as the High-Arctic Large Igneous Province (HALIP). K–Ar dating of numerous dolerites sampled from many locations across Svalbard define a narrow time span of this magmatism from 125.5±3.6 to 78.3±2.6 Mya. Discrete peaks of intensive activity occurred at 115.3, 100.8, 91.3 and 78.5 Mya corresponding to (1) breakup of the continental crust and formation of an initial rift as a result of mantle plume activity, located in the southern part of the Alpha Ridge; (2) magmatic activity related to spreading along the Alpha Ridge that led to the development of the initial oceanic crust and (3) continuation of spreading along the Alpha Ridge and termination of magmatic activity related to HALIP (last two peaks at 91.3 and 78.5 Mya).

• Dolerite
• geochemistry
• petrogenesis
• K–Ar whole rock ages
• Svalbard
• Cretaceous

Acknowledgements

Fieldwork in Svalbard was supported by the Polish Ministry of Science and Higher Education (grant nos. N 307 069 32/4103 and IPY/279/2006) and made possible by the scientific cruises of the SBS Horyzont II. The field assistance of Przemyslaw Karcz, Marcin Klisz and Stanislaw Mazur during the summer seasons of 2005 and 2007 is gratefully acknowledged. Special thanks are due to the Norwegian Petroleum Directorate for inviting KPK to join its expeditions to eastern Svalbard in August 2007 and August 2009 on board the MS Kongsøy. Atle Mørk, of SINTEF Petroleum Research, is thanked for dolerite samples from Isormen, Wilhelmøya and Wahlbergøya. The authors are grateful to Professors Krzysztof Birkenmajer and Raymond Macdonald for valuable suggestions and for critical reviews of an earlier draft of the article. We would like to thank Richard Ernst, Solveig Estrada and Friedhelm Henjes-Kunst for their careful reviews of this article and their constructive comments. The authors are also grateful to Piotr Dzierzanowski and Lidia Jezak for their help with the electron probe micro-analyses, to Bozena Lacka for her help during preparation of the samples for geochemical and geochronological analyses and to Ewa Deput for preparation of the thin sections.