Structural paragenesis as an indicator of the origin of alkaline rocks in the ijolite-urtite arc of the Khibiny pluton, Kola Peninsula

摘要

The results of structural analysis of the ore-bearing complex in the Khibiny pluton are presented. A multistage history of the formation of the ijolite-urtite arc structure has been established. The conic shear zone that determines the structural appearance of the ore-bearing complex is related to the early deformation stage. Only massive ijolite and melteigite are rocks of predeformation matrix. All other rock varieties and apatite ore are syndeformation (gneissic ijolite) or postdeformation (urtite, apatite ore) and thus are not magmatic in origin. The formation of the Paleozoic conic shear zone was most likely predetermined by a Precambrian central-type structure, more precisely, by a binucleus vortex structure related to shearing.