Geochemistry of Paleozoic Dolerite Dikes in the Northeastern Kola Peninsula and Their Relations to Flood-Basalt and Alkaline Magmatism

The paper presents data on dolerite dikes in the Murmansk block in the northeastern Kola Peninsula. The dikes belong to a Middle Paleozoic flood-basalt association, which is a principal element of the large-scale plume-lithospheric process in the area of the Barents Sea. According to their geological, petrological, and geochemical features, the dolerite dikes are classified into two groups: older and younger, which pertain to the initial and final evolution of the large igneous province produced under the effect of the Barents Sea plume at 450-340 Ma. One of the results of the plume-lithosphere interaction was the origin of the Eastern Barents Basin, which is filled with large volumes of basalts, and this predetermined the further subsidence of the area in Meso-Cenozoic time and the accumulation of thick sedimentary sequences with significant hydrocarbon resources. The peripheries of the area with products of basaltic magmatism are marked by alkaline rock complexes. The largest of the latter are the intrusions of the Kola Province and kimberlites in Archangelsk oblast. The dolerites of the dikes abound in xenogenic grains of zircon, which were dated at 2.7, 1.8, 1.3, 0.7 Ga. These age values suggest that the parental melts may have been derived in the lower crust and that the magma-generating processes may have evolved in the root zone of an ancient rift system.