Abstract

—The East Tannu-Ola sector of the Tuvinian magmatic belt is composed of Early Cambrian volcanosedimentary rocks of an island-arc association (Kadvoi, Serlig, and Irbitei Formations), which are intruded by granitoid massifs of different ages (from Cambrian to Devonian) of the Tannu-Ola areal pluton. We analyzed the structural and geologic position, chemical composition, metallogenic signatures, and geochronological (U/Pb) and isotope-geochemical (Sm/Nd and Rb/Sr) characteristics of Early Paleozoic granitoids of the Ungesh pluton (western part of the Tannu-Ola areal pluton). The available and our new data made it possible to establish the specific chemical parameters, age sequence, duration, intensity, and metallogeny of granitoid magmatism in the East Tannu-Ola sector of the Tuvinian magmatic belt. An early Cambrian (534–518 Ma) gabbro–plagiogranite complex similar to the Maina complex in West Sayan has been recognized in the Ungesh pluton. The age and metallogeny of the middle–late Cambrian (508–492 Ma) Tannu-Ola diorite–granodiorite–plagiogranite and Late Ordovician (451–447 Ma) Argolik granite–leucogranite complexes have been refined. Granitoids of the early Cambrian complex formed probably at the initial stage of formation of an island arc, in association with the Kadvoi–Serlig basalt–andesite–rhyolite complex. It is in these granitoids that early low-productivity gold–sulfide–quartz veins and veinlets originated. Granitoids of the Tannu-Ola complex formed at the initial stage of evolution of the accretion–collision system. Magnetite-containing skarns and numerous vein–veinlet zones of late high-productivity gold-sulfide-quartz mineralization evolved in these granitoids. Granitoid massifs of the Argolik complex formed at the final stage of evolution of the accretion–collision system and probably played a crucial role in the regeneration of ore mineralization in some areas.

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