Characteristics of Fluid Inclusions and Metallogenesis of Annage Gold Deposit in Qinghai Province, China

• 作者: Baorong Yang Jianqing Lai Jinjin Tao Peijiao Ju Xiaoyun Wang
• 来源期刊: 地质学期刊(英文)
• 学科: 地球科学
• 关键词: FLUID INCLUSIONS Hydrogen-Oxygen Isotope ORE-FORMING FLUID METALLOGENESIS Annage China
• 年，卷（期）: 2015,（11）
• 页码范围: 780-794
• 页数: 15页
• 分类号: P61

摘要

The?Annage gold deposit is located at the east part of the eastern Kunlun orogenic belt. The characteristics of ore-forming fluids and metallogenesis were discussed by using fluid petrography, micro-thermometry and hydrogen-oxygen isotope analysis. Three stages, namely quartz-pyrite stage (A), quartz-polymetallic-sulfide stage (B) and quartz-ankerite stage (C) were included in the hydrothermal process as indicated by the results of this study. Inclusions developed in ore-bearing quartz veins from stages A and B are of three types: aqueous inclusions (type I), CO2-bearing inclusions (type II) and pure CO2?inclusions (type III). All three types of inclusions, mainly type I, are presented in stage A, having homogenization temperatures at 180°C - 360°C, and salinities ranging from 0.53% to 21.44%. In addition to development of type I inclusions, type II and III inclusions increase significantly in stage B, with homogenization temperatures ranging from 160°C to 330°C, and salinities are from 1.32% to 22.01%. Based on micro-thermometry, fluids in Annage deposit are of H2O-NaCl-CO2?type with medium-high temperature (140°C - 395°C) and medium-low salinity (0.53% - 22.01%). Results of hydrogen-oxygen isotope analysis show that ore-forming fluid is mainly CO2-rich magmatic fluid, mixed with shallow groundwater or metamorphic hydrothermal in the late mineralization stages. Calculated metallogenic pressures are in the range of 79 - 130MPa corresponding to a maximum depth of 4.8 km. The Annage deposit is a mesothermal quartz vein type gold deposit.