Zircon U–Pb and sericite Ar–Ar geochronology, geochemistry and S–Pb–Hf isotopes of the Zebuxia Pb–Zn deposit, Tibet, southwestern China
Yunhui Zhang, Rongwen Yao, Ying Wang, Ji Duo, Huawen Cao
Abstract
The Zebuxia Pb–Zn deposit is located in southern Tibet and belongs to the western segment of the Northern Gangdese Metallogenic Belt. Based on the characters of deposit geology, geochronology, geochemistry, and S–Pb-Hf isotopes, the genesis and spatial–temporal evolution of the Pb–Zn mineralization in the Northern Gangdese Metallogenic Belt were elucidated. The results of sericite Ar-Ar dating yields an isochron age of 55.2 ± 0.8 Ma, accordant with the zircon U-Pb 54.9 ± 0.4 Ma age obtained from the biotite granite. The biotite granite is of high-K calc–alkaline and metaluminous with I-type affinity. The δ34S values of galena and pyrite range from + 1.3‰ to + 3.5‰ (mean = +2.4‰) and show magmatic origin. Pb isotopic results of galena and pyrite show the 206Pb/204Pb values are 18.611–18.666 (mean = 18.631), 207 Pb/ 204Pb values are 15.654–15.718 (mean = 15.678), 208Pb/204Pb values are 38.982–39.195 (mean = 39.064), representing the orogenic feature with upper crustal source mixed by mantle-derived materials. Based on the comprehensive analyses above, the Zebuxia Pb–Zn deposit belongs to structure–hydrothermal–filling type deposit. Combined with previous studies, we propose that the magmatic intensity determine the mineralization scale of the Pb–Zn deposits, while the nature of ore–related plutons constrain the source of mineralized fluids in the Northern Gangdese Metallogenic Belt. The investigation of the Zebuxia Pb–Zn deposit reveals the western section of the Northern Gangdese Metallogenic Belt has great prospecting potential as well.