The Turiy Massif, Kola Peninsula, Russia: Isotopic and Geochemical Evidence for Multi-source Evolution

Abstract

The Turiy Massif, lying within the Kandalaksha Graben, and on studies during the last century [summaries have been given by Bell (1989) and Bell & Keller (1995)]. Current the southern coast of the Kola Peninsula, contains carbonatites, phoscorites, melilitolites, ijolites and pyroxenites within one central theories for their origin include the derivation of carbonatites as primary magmas (e.g. Bailey, 1993; Harmer and four surrounding satellite complexes. Sr-Nd isotopic data from the central complex phoscorites and carbonatites, and the nearby & Gittins, 1998), their differentiation from a silicate parent (e.g. Kjarsgaard, 1997), or their separation from Terskii Coast kimberlites, combined with other recently published data on the Devonian Kola Alkaline Province, allow us to redefine a silicate parent by liquid immiscibility (e.g. Brooker, 1998). To evaluate the role of each of these processes the position of the Kola Carbonatite Line (KCL) of Kramm (European Journal of Mineralogy 5, [985][986][987][988][989] 1993). We within an individual complex or intrusion, it becomes important to assess the geochemical relationships between propose that the revised-KCL mantle sources include a lower-mantle plume, and a second enriched source, which also contributed to the spatially related silicate and carbonatite rocks. In addition, trace element and isotopic characteristics from both Terskii Coast and Archangelsk kimberlites. The Turiy Massif silicate rocks and northern complex carbonatites have more enriched carbonatite and silicate rocks may help to characterize the mantle source(s) from which the magmas were de-isotopic signatures than the distinct, and depleted signatures of the central complex phoscorites and carbonatites, particularly with rived. The Turiy Massif, which has been subjected to little alteration since its intrusion, and for which a com-respect to Sr. This is probably due to the contamination of parental magmas, originally derived from the KCL end-members, by crustal prehensive suite of drill core samples exists, offers an ideal opportunity for such a detailed study. material. The phoscorites and carbonatites show unusually enriched stable isotope 13 C PDB values with respect to their conjugate 18 O SMOW values. The trace element signatures of the silicate rocks are generally consistent with derivation from the magma sources proposed above.