A sample dredged from the Alpha Ridge records evidence of an emergent volcanic setting at 90 Ma

Abstract Recovering geological samples from the deep basins and ridges of the central Arctic Ocean presents significant challenges because of remote access and thick ice cover. During the 2016 Canada-Sweden Polar Expedition to the Arctic Ocean, volcaniclastic breccia was dredged from the Alpha Ridge, part of an underwater mountain chain extending from the Canadian polar margin to the Siberian shelf. Argon geochronology of plagioclase crystals within glassy lava fragments dates the sample to 90.4 ± 0.26 Ma. The geochemical composition of basalt clasts in the volcaniclastic breccia closely resembles that of igneous rocks from the High Arctic Large Igneous Province suggesting that the Alpha Ridge was an active volcanic feature within the circum-Arctic in the Late Cretaceous. Our results support lava–water interactions in a littoral environment, driven by the growth and emergence of a central igneous platform and accompanied by eruptive activity at constructional volcanic edifices along its margins.