Stable Isotopes and Halogen Geochemistry of the Huayuan Carbonate-hosted Pb-Zn Ore District, South China: Implications for the Salt Source of Ore-forming Fluids  

作　　者：YANG Zhen JIANG Mengjie ZHAO Shaorui DING Zhenju HE Mouchun 

机构地区：[1]School of Earth Resources,China University of Geosciences,Wuhan 430074,China [2]State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences,Wuhan 430074,China

出　　处：《Acta Geologica Sinica(English Edition)》2022年第2期506-516,共11页地质学报（英文版）

基　　金：financially supported by the Geological Survey Program of China Geological Survey Bureau(Grant No.12120114016601)。

摘　　要：The Huayuan Pb-Zn ore district in China,located in western Hunan Province,is a giant carbonate-hosted Pb-Zn ore district.The source of ore-forming brines in this ore district remains poorly constrained.Whether the highly saline brines are derived from evaporated seawater or dissolved evaporates continues to be intensely debated.Carbonate minerals associated with Pb-Zn mineralization haveδ^(13)CV-PDB andδ^(18)OV-SMOW values ranging from−5.55‰to+1.35‰(mean value of−0.69‰;n=14)and+16.28‰to+25.05‰(mean value of+20.22‰;n=14),respectively.This indicates that carbonate minerals are dominantly formed from dissolved ore-hosted carbonate rocks.Theδ^(34)S values of sulfides range from+20.2‰to+36.8‰,with an average value of+30.0‰(n=27).These results suggest that sulfur is predominantly derived from the thermochemical sulfate reduction of marine sulfate.The crush-leach analyzed solute data of fluid inclusions in sphalerite show the ore-forming fluids have Cl/Br molar ratios range from 118 to 384,and Na/Br molar ratios from 39 to 160(n=8).These Cl/Br ratios of hydrothermal fluid are much lower than those of seawater(657 to 564),but are consistent with bittern brines through early halite precipitation.We propose that ore-forming fluids are mainly derived from evaporitic basin brines,which leached base metals from the basement and/or country rocks.The brine then migrated to the basin margins through clastic rocks of basement and then precipitated sulfides by thermochemical sulfate reduction.

关 键 词：fluid inclusions stable isotopes halogen elements ore genesis Huayuan Pb-Zn ore district 

分 类 号：P618.4[天文地球—矿床学] P597.2[天文地球—地质学]