Middle-Late Triassic magmatism in the Hutouya Fe-Cu-Pb-Zn deposit, East Kunlun Orogenic Belt, NW China: Implications for geodynamic setting and polymetallic mineralization

The Hutouya Pb-Zn mining district in the Qiman Tagh region in NW China is a zoned skarn district with inner Fe-Sn-Cu-Co ores and outer Pb-Zn skarn mineralization. Temporal coincidence of 40Ar/39Ar plateau age of orestage phlogopite (226.9 +/- 1.5 Ma) with weighted mean LA-ICP-MS U-Pb ages of zircons (230.3 +/- 3.7 and 221.6 +/- 1.3 Ma) and 40Ar/39Ar plateau ages of biotite (229.6 +/- 2.3 and 224.7 +/- 2.6 Ma) in the spatially-associated monzogranite strongly suggest a genetic relationship between skarn formation in the Hutouya metallogenic district and intrusion of the monzogranite suite. Major and REE analyses indicate the Hutouya monzogranites are A-type granites that belong to the high-K talc-alkaline series. Hafnium isotope data are consistent with a crust-mantle mixing source. Geochemical characteristics of the Middle-Late Triassic Indosinian (235-204 Ma) granitoids associated with mineralization in the Qiman Tagh region are consistent with an origin as post-collisional, mantle-derived magmas that underplated the lower crust in the East Kunlun orogen in an extensional setting, causing lower crustal melting and subsequent mixing and assimilation that produced magmas fertile for mineralization.