Formation and evolution of multistage ore-forming fluids in the Miocene Bangpu porphyry–skarn deposit, Southern Tibet: insights from LA–ICP–MS trace elements of quartz and fluid inclusions

Zhao, Xiaoyan, Zheng, Yuanchuan, Yang, Zhusen, and Hu, Yi (2020) Formation and evolution of multistage ore-forming fluids in the Miocene Bangpu porphyry–skarn deposit, Southern Tibet: insights from LA–ICP–MS trace elements of quartz and fluid inclusions. Journal of Asian Earth Sciences, 204. 104556.

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Abstract

The large Bangpu Mo–Cu–Pb–Zn deposit, is a Mo-rich (~0.089%), Cu-poor (~0.32%) porphyry–skarn deposit located in the northeastern Gangdese porphyry copper belt (GPCB), Southern Tibet. In this study, LA–ICP–MS data for fluid inclusions and quartz formed during different stages of the mineralization are used to (1) constrain changes in fluid composition during mineralization; (2) infer the origin, transport pathways, and conditions of ore precipitation; and (3) explore the influence of magma chamber on fluid exsolution and shallow mineralization. The Cu content of the vapor-rich (VL) inclusions is higher than that of the halite-bearing (LVH) inclusions, while the Mo, Pb, and Zn contents of the VL and LVH inclusions are similar, indicating that Mo, Cu, Pb, and Zn had a common source, which is inferred to be the intermediate-level magma chamber. The metal contents of fluid inclusions in the early stage potassic alteration-related vein (A vein) and later stage sericitic alteration-related vein (B vein) are similar but variable, implying the intermediate-level magma chamber was too small to form a large stable fluid system. The enrichment of Mo, Pb, and Zn in the Bangpu deposit relative to other porphyry deposits in the GPCB is related to the participation of ancient crustal material. A comparison of our results with those from super-large porphyry Cu deposits elsewhere indicates that metal-rich fluids are not the sole factor to form ore deposits, and the variability of metal contents in the early exsolved fluids is a better predictor of mineralization potential than absolute metal concentrations.

Item ID: 66596
Item Type: Article (Research - C1)
ISSN: 1878-5786
Keywords: Bangpu porphyry system, Fluid evolution, Gangdese porphyry copper belt, In situ analysis of quartz and fluid inclusion, Mo-Pb-Zn enrichment
Copyright Information: © 2020 Elsevier Ltd
Funders: National Natural Science Foundation of China, National Key Research and Development Project of China (NK), Fundamental Research Funds for the Chinese Academy of Geological Sciences
Date Deposited: 27 Apr 2021 02:09
FoR Codes: 37 EARTH SCIENCES > 3705 Geology > 370508 Resource geoscience @ 100%
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