Ore Geology Reviews   2017 年 80 卷

2017.01.01

The Duolong district in central Tibet hosts a number of porphyry as well as high sulfidation epithermal copper??“gold deposits and prospects, associated with voluminous calc-alkaline volcanism and plutonism. In this study, we present new geochronological, geochemical, isotopic and mineralogical data for both economically mineralized and barren porphyritic intrusions from the Duobuza and Naruo porphyry Cu??“Au deposits. Zircon U??“Pb analyses suggest the emplacement of economically mineralized granodiorite porphyry and barren granodiorite porphyry at Naruo deposit took place at 119.8???±??1.4??Ma and 117.2???±??0.5??Ma, respectively. Four molybdenite samples from the Naruo deposit yield an isochron Re??“Os age of 119.5???±??3.2??Ma, indicating mineralization occurred synchronously with the emplacement of the early granodiorite porphyry. At Duobuza deposit, the barren quartz diorite porphyry intruded at 119.5???±??0.7??Ma, and two economically mineralized intrusions intruded at 118.5???±??1.2??Ma (granodiorite porphyry) and 117.5???±??1.2??Ma (quartz diorite porphyry), respectively. Petrographic investigations and geochemical data indicate that all of the porphyritic intrusions were oxidized, water rich, and subduction-related calc-alkaline magmas. Zircons from the porphyritic intrusions have a wide range in the ??