Mineralization timing and genesis of the Qukulekedong Au–Sb deposit in the East Kunlun Orogenic Belt, northern tibetan Plateau: Constraints from arsenopyrite Re–Os ages, zircon U–Pb ages, and Lu–Hf isotopes

Abstract

The Qukulekedong Au–Sb deposit is the first large Au–Sb deposit discovered in the western section of the East Kunlun Orogenic Belt. Even though the significance of the deposit is important, mineralization timing and genesis of the deposit have remained elusive. This study integrated a regional geological survey and the analysis of deposit characteristics with newly acquired geochemical data (Re–Os dating, LA–ICP–MS zircon U–Pb dating, and Lu–Hf isotopes) to gain insights into the chronology and genesis of this deposit. The deposit is closely related to granodiorite and diorite porphyry intrusions in space. The orebody occurs in the inner and outer contact zones of the intrusions and is characterized by disseminated, quartz veins, and breccia type mineralization. The main Au-bearing minerals are pyrite, arsenopyrite, and stibnite. The zircon U–Pb ages of the granodiorite and diorite porphyry are 214.8 ± 1.1 Ma and 211.0 ± 3.7 Ma, respectively. The Re–Os isochron age of Au-bearing arsenopyrite is 209 ± 12 Ma. The εHf(t) values of zircons from the granodiorite range from 4.78 to 9.16, the εHf(t) of zircons from the diorite porphyry range from −1.81 to 7.05, and the initial 187Os/188Os value of Au-bearing arsenopyrite is 0.7851 ± 0.0079, indicating that the magmas of deposit were derived from the lower crust and ore-forming materials were mainly derived from ancient lower crust. These results show that the Qukulekedong Au–Sb deposit was formed in a Late Triassic post-collision extensional background and is an Au–Sb deposit related to the crust-derived magmatic activity. There is still significant prospecting potential in the depth of the deposit.