Late Mesozoic magmatism in Svalbard: A review

Late Mesozoic mafic igneous rocks are widespread across the Arctic region, and are collectively referred to as the High Arctic Large Igneous Province (HALIP). In Svalbard the HALIP is represented by the Diabasodden Suite, an extensive system of predominantly basic intrusive doleritic rocks. Associated lava flows are exposed on the far east of the archipelago. Two main igneous centres have been proposed: (1) Central Spitsbergen and (2) the eastern Svalbard dolerite belt, spanning Hinlopenstretet and the islands of Edgeøya and Barentsøya. Offshore seismic and magnetic data suggest a link between the Svalbard and Franz Joseph Land igneous exposures. Intrusions occur predominantly as sills, up to 100 m thick and laterally continuous for up to 30 km. Dykes are present locally, and range in thickness from < 10 m up to 100 m. A compilation of published geochemical data reveals that the vast majority of samples have a basaltic geochemical signature. Comparison to HALIP rocks elsewhere in the Arctic, including paleotectonic reconstructions, suggests that the Diabasodden Suite formed as part of an intra-plate basaltic complex originating from a source near the Alpha Ridge. Apart from Late Mesozoic magmatism, Svalbard has also experienced magmatic activity both before and after the intrusion of the Diabasodden Suite dolerites. These are distinguished on the basis of their geochemical signature and timing. Timing of the Diabasodden Suite magmatism is currently poorly constrained. More than 130 radiometric (Ar-Ar and K-Ar) ages have been published, with a wide range of ages (ca. 75-145 Ma). Modern radiometric dating (U-Pb) on three samples suggests a shorter-lived intrusion pulse at ca. 124.5 Ma (i.e. early Aptian). While much work has been conducted on the Diabasodden Suite in the past, a detailed synthesis of this widespread unit is presently missing. In this contribution we discuss the current knowledge on the Diabasodden Suite, synthesizing and reviewing the past studies as well as pointing out possible future research directions.