Age and Geodynamic Conditions of Formation for the Neoproterozoic Gold-Bearing Granitoids in the Eastern Sayan
The paper discusses results of the petrogeochemical and geochronological studies of the Tainsky granitoid stock containing the Tainsky gold ore deposit in the East Sayan. The Tainsky granitoid stock intrudes through the ultrabasites of the Ospa-Kitoi ultrabasitic massif. Granitoids are part of an ophiolite cover which overlap over the rocks of the Tuva-Mongolian microcontinent Archean foundation. Obtained by three independent methods (U–Pb, Re–Os, <sup>40</sup>Ar/<sup>39</sup>Ar) consistent isotopic age values in the range of 850–860 Ma, are evidence of the Neoproterozoic age of granitoid magmatism and its genetic relationship with gold-(±copper)-porphyry mineralization. The geological setting, geochemical characteristics, and age of the Tainsky granitoid stock allow us to attribute these rocks to the Neoproterozoic Dunzhugur island arc sequences. Isotopic age values o-btained by Rb–Sr and <sup>40</sup>Ar/<sup>39</sup>Ar methods which characterized by lower closure temperatures of isotopic systems allow to distinguish several tectonic-thermal events at 650, 435, 339–333, and 280–223 Ma.