The Turiy Massif, Kola Peninsula, Russia: Isotopic and geochemical evidence for multi-source evolution

The Turiy Massif, lying within the Kandalaksha Graben, and on the southern coast of the Kola Peninsula, contains carbonatites, phoscorites, melilitoli tes, ijolites and pyroxenites within one central and four surrounding satel lite complexes. Sr-Nd isotopic data from the central complex phoscorites an d carbonatites, and the nearby Terskii Coast kimberlites, combined with oth er recently published data on the Devonian Kola Alkaline Province, allow us to redefine the position of the Kola Carbonatite Line (KCL) of Kramm (Euro pean Journal of Mineralogy 5, 985-989, 1993). We propose that the revised-K CL mantle sources include a lower-mantle plume, and a second enriched sourc e, which also contributed to the Terskii Coast and Archangelsk kimberlites. The Turiy Massif silicate rocks and northern complex carbonatites have mor e enriched isotopic signatures than the distinct, and depleted signatures o f the central complex phoscorites and carbonatites, particularly with respe ct to epsilon Sr. This is probably due to the contamination of parental mag mas, originally derived from the ITCL ad-members, by crustal material. The phoscorites and carbonatites show unusually enriched stable isotope delta C -13(PDB) values with respect to their conjugate delta O-18(SMOW) values. Th e Grace element signatures of the the silicate rocks are generally consiste nt with derivation from the magma sources proposed above.