Infrared microthermometric and noble gas isotope study of fluid inclusions in ore minerals at the Woxi orogenic Au–Sb–W deposit, western Hunan, South China
Ya-Nan Zhu;Jian-Tang Peng
刊名Ore Geology Reviews
2015
卷号65期号:Part 1页码:55-69
关键词Fluid Inclusions noble Gas Isotope ore Minerals orogenic Au–sb–w Deposit
英文摘要

The Woxi Au–Sb–W deposit, hosted by the Neoproterozoic low-grade metamorphic clastic rocks, is located in a brittle-ductile shear zone within the Xuefengshan Range, South China. Orebodies are predominantly banded quartz veins, which are strictly controlled by bedding faults and display significant vertical extents (up to 2 km) without obvious vertical metal zoning. Fluid inclusions hosted in quartz, scheelite, and stibnite from quartz–scheelite and quartz–sulfide–gold veins have been studied using conventional and infrared microscopy, respectively. Four types of fluid inclusions were identified based on petrography, including type I (two-phase, liquid-rich aqueous inclusions), type II (two- or three-phase, CO2-rich inclusions), type III (two-phase, vapour-rich aqueous inclusions), and type IV (single-phase aqueous inclusions). The fluid inclusions in ore minerals (scheelite and stibnite) and their coexisting quartz largely share similar characteristics in terms of their types, homogenization temperatures and salinities. This is consistent with the fact that these ore minerals are always intergrown with quartz. Microthermometric and laser Raman data indicate a low-to-moderate temperature (140–240 °C), low salinity (< 7.0 wt.% NaCl equiv.), CO2-rich, N2-bearing aqueous ore-forming fluid. Such fluid is further identified as a deeply non-magmatic crustal fluid rather than a mantle-source fluid by the significantly low 3He/4He ratios (0.002–0.281 Ra), and a small amount of meteoric water or host-rock-buffered fluid could be involved. W ore precipitation was probably associated with mixing between a deeply-originated crustal fluid and host-rock-buffered fluid based on the fluid inclusion features in scheelite and quartz-I. However, Au and Sb ore deposition probably resulted from boiling which was caused by the marked pressure drop. Geological features (such as banded structure and crack-sealing structure) also indicate that fluid pressure fluctuation induced by fault-valve mechanism occurred during ore precipitation. These characteristics of the ore-forming fluids in the Woxi deposit are in good agreement with the definition of orogenic gold deposits and the Woxi Au–Sb–W deposit is probably an atypical orogenic gold deposit for its unique ore-forming element association.

语种英语
内容类型期刊论文
源URL[http://ir.gyig.ac.cn/handle/42920512-1/9545]  
专题地球化学研究所_矿床地球化学国家重点实验室
作者单位1.State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, PR China
2.University of Chinese Academy of Sciences, Beijing 100049, PR China
3.Key Laboratory of Metallogenic Prediction of Nonferrous Metals, Ministry of Education, School of Geosciences and Info-physics, Central South University, Changsha 410083, PR China
推荐引用方式
GB/T 7714
Ya-Nan Zhu;Jian-Tang Peng. Infrared microthermometric and noble gas isotope study of fluid inclusions in ore minerals at the Woxi orogenic Au–Sb–W deposit, western Hunan, South China[J]. Ore Geology Reviews,2015,65(Part 1):55-69.
APA Ya-Nan Zhu;Jian-Tang Peng.(2015).Infrared microthermometric and noble gas isotope study of fluid inclusions in ore minerals at the Woxi orogenic Au–Sb–W deposit, western Hunan, South China.Ore Geology Reviews,65(Part 1),55-69.
MLA Ya-Nan Zhu;Jian-Tang Peng."Infrared microthermometric and noble gas isotope study of fluid inclusions in ore minerals at the Woxi orogenic Au–Sb–W deposit, western Hunan, South China".Ore Geology Reviews 65.Part 1(2015):55-69.
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