Age and origin of subalkaline magmatic series of the Khibiny-Lovozero complex

Results of the study of miaskite syenites of the Lovozersky massif, pulaskites of the Khibiny massif and rocks of the larvikite-lardalite series of the Khibiny massif, as well as subalkaline volcanics preserved as remnants in their roof are presented. The studied rocks are characterized by a low agpaitic coefficient 1, by the absence of typical minerals of ultra-alkaline rocks (eudialyte, enigmatite, etc.) as well as by the presence of zircon. The morphological features and chemical composition of zircon from the Lovozero massif miaskite syenite indicate magmatic origin of the massif, allowing to determine the age of crystallization of miaskites at 373 ± 5 Ма. The isotope-geochemical characteristics of the rocks of the subalkaline series indicate the mantle origin of the Lovozero massif miaskites, the absence of signs of crustal contamination in them and their formation during the evolution of the ankaramite melt. The formation of the pulaskites of the Khibiny massif, which occurred according to a similar scenario, was complicated by the assimilation of crustal material, proportion of which, according to the model calculations, did not exceeded ten percent.