Tectono-magmatic evolution of the Greenland−Iceland−Norway ridge complex and the Jan Mayen hotspot in the Arctic Atlantic Ocean: Constraints from in situ trace elements and Sr isotopes of minerals

Abstract

The subarctic North Atlantic Ocean has experienced a complex and gradual magmatic evolution, including continental breakup, mature seafloor spreading, and episodic ridge jumps. Here, we present new in situ major-element, trace-element, and Sr isotopic compositions for minerals (olivine, clinopyroxene, and plagioclase) from the Jan Mayen microcontinent (Integrated Ocean Drilling Program [IODP] Sites 907 and 985), Reykjanes Ridge (Site 983), Greenland Basin (Site 913), and Knipovich Ridge (Site 911) volcanic samples in the Arctic Atlantic Ocean. The Jan Mayen hotspot−type and Iceland plume−type volcanic rocks have a common magma source. The former were likely derived from the latter by further fractional crystallization, resulting in their distinct geochemical features. The in situ incompatible element and isotopic compositions show that the normal mid-ocean-ridge basalt spreading ridge feature for the older (>14 Ma) system and the enriched plume feature for the younger (1.521 Ma and 1.049 Ma) system likely indicate plume-ridge interaction and the evolution from mid-ocean-ridge−type to plume-type magmatism beneath the Norwegian−Greenland Sea. The disequilibrium of Sr isotopes in plagioclase among the groundmass, phenocryst cores, and rims is likely due to heterogeneous compositions beneath the North Atlantic Ocean basin, with the contamination of thick continental crust and the influence of H2O-enriched melts originating from the deep Iceland plume.