Zircon UPb geochronology and geochemistry of ore-bearing rhyolites in the Fuxingtun Ag–Pb–Zn deposit, Great Xing'an Range, NE China: Constraints on petrogenesis and tectonic setting

The Fuxingtun Ag–Pb–Zn deposit, located in the Right Front Banner of Horqin, Inner Mongolia, is a superlarge Ag–Pb–Zn deposit discovered in 2019 in the southern-central Great Xing'an Range. In this work, LA–ICP–MS zircon UPb, petrogeochemical and zircon Hf isotope data were obtained from ore-bearing rhyolites in the Manketouebo Formation in the Fuxingtun mining area. The zircon UPb ages of the eight rhyolite samples range from 140.1 Ma to 133 Ma, corresponding to the Early Cretaceous. The geochemical characteristics reveal that the rhyolites belong to the high-k calc-alkaline peraluminous series and are characterized by high silicon, alkali and aluminum contents and low iron, magnesium and calcium contents. The total amount of rare earth elements (REEs) is low, and the light and heavy REEs exhibit a certain degree of fractionation, with a moderate negative Eu anomaly. The enrichment of Rb, Th, U, K, Zr, and Hf and the depletion of Ba, Sr, P, Ti, Nb, and Ta correspond to the geochemical characteristics of I-type rhyolites. The source of the rhyolitic magma may have been the remelting of Paleozoic juvenile crust in a postcollisional extensional geotectonic environment.