40Ar-39Ar and Rb-Sr age constraints on the formation of Sukhoi-Log-style orogenic gold deposits of the Bodaibo District (Northern Transbaikalia, Russia)
А. В. Чугаев, A. E. Budyak, Yulia O. Larionova, И. В. Чернышев, А. В. Травин, Yulia I. Tarasova, Б. И. Гареев, G. А. Batalin, Irina V. Rassokhina, Т. И. Олейникова
Abstract
The Bodaibo District (the Irkutsk Region of Russia) is a world-class gold-mining subprovince comprising a total of 13 large- and medium-scale black-shale-hosted orogenic gold deposits known as the Sukhoi Log-style gold deposits (Ivanov, 2014). The gold mineralization of the Sukhoi Log-style deposits is represented by early veinlet-disseminated sulfide ores, which have the main economic significance, and late native gold-bearing quartz veins with only minor gold reserves. This paper presents the results of Rb-Sr и 40Ar-39Ar dating of the gold mineralization in four Sukhoi Log-style deposits: Verninsky, Golets Vysochaishy, Ozherelie, and Ikan, with the estimated gold reserves of 143, 86, 6.5, and 7.0 metric tons, respectively. The Rb-Sr and 40Ar-39Ar data obtained indicate the existence of two ore-forming events in the district. The early sulfide veinlet-disseminated ores formed in the Silurian (450–430 Ma) and postdate the peak of the regional metamorphism in the region.. During the middle Carboniferous (ca. 330 Ma), the rejuvenation of ore-forming processes resulted in the formation of native gold-bearing quartz veins. The constraints on the ages of gold mineralization of the Sukhoi Log-style deposits are of key importance for understanding their genesis and the features of evolution of the Bodaibo District as a gold-mining subprovince.