Comparative geochemical characteristics and genesis of large polystage plutons in the core and periphery of the different age areas of the Mongol-Okhotsk fold belt

The Early Mesozoic Baga-Khentey pluton is the fragment of the Dauria-Khentey batholith, which could have formed due by the mantle plume action on lower horizons of the continental crust within the zone of collisional compression by closing of the Mongol-Okhotsk ocean. The batholith and their peripheral zones possibly formed from the mantle and crustal sources of magma. The Ikh-Narotin-Khid Massif is located on the border of the rifting zones on periphery of the Late Mesozoic area. The petrographic and geochemical affinity of granitoids of the Ikh-Narotin-Khid massif and composition of gneisses from the country rocks might indicate that this was the substratum in formation of palingenic granites of the calc-alkali series. The distinctions in rock composition of the large plutons consist in minor differentiation of the Baga-Khentey Massif rocks probably related to the anatexis conditions and origin of melts in the collisional compression setting. The granites of the Ikh-Narotin-Khid Massif formed in the extension setting favorable for deep differentiation of magmatic melts.