Sources of the magmatic rocks of the Mendeleev Rise, Arctic Ocean: Evidence from isotope-geochemical data

Abstract

Mineralogical-petrographic and isotope-geochemical studies were carried out for basic and intermediate magmatic rocks derived by deep-water drilling and dredging at the test sites from 79.02° N to 83.09° N, Arctic Ocean (AO), during expedition “Arktika-2012” with the icebreaker Kapitan Desnitsyn. Volcanic bedrock samples derived from the drill holes at the foot of the Mendeleev Rise are grouped into the low- and moderate alkali rocks, showing narrow ranges in the initial Nd (ɛNd(T) from +4.3 to +7.0) and Sr (87Sr/86Sr from 0.70365 to 0.70495) isotope ratios, and correspond to the volcanic rocks of the oceanic islands and rises in the discriminant isotope and geochemical diagrams. Gabbro-dolerite samples dredged from the slopes of the Mendeleev Rise are grouped into the low-alkali field and show wide variations in Nd (ɛNd from −33.1 to +2.9) and Sr (87Sr/86Sr from 0.7050 to 0.7233) isotope compositions, being similar to the Siberian flood basalts and, possibly, other rocks of continental genesis.