湖南沃溪金锑钨矿床成矿流体研究

发布时间：2018-05-08 03:00

  本文选题：沃溪金锑钨矿床 + 流体包裹体　； 参考：《成都理工大学》2017年硕士论文

【摘要】：沃溪金锑钨矿床地处湘西,位于雪峰构造带转折部位。该矿床产于晚元古界板溪群马底驿组浊积岩地层之中,受地层与构造控制明显,以金、锑、钨均达到工业品位而闻名于世,是我国著名的大型金锑钨矿床。矿体分为似层状矿体及脉状矿体,主要矿石矿物为自然金、辉锑矿和白钨矿,围岩蚀变类型主要有褪色化、黄铁矿化以及硅化。本文在前人研究的基础上,采用流体包裹体的研究方法对成矿流体进行研究,采集不同期次不同阶段的石英、白钨矿和方解石样品,进行室内观察、描述、测试以及计算,得出如下结论:流体包裹体主要包括H_2O包裹体和CO_2-H_2O包裹体两类,以H_2O包裹体为主。成矿作用包含四个阶段,第一阶段均一温度变化范围为117~185℃,平均157.6℃,成矿温度介于173~214℃,盐度介于3.85~6.52wt%Na Cl,平均5.25wt%Na Cl,pH值5.74,呈现出弱碱性,Eh值-0.0578,表现出弱还原性,f_(O2)值为10~(-50.84),f_(CO2)值为3.202,f_(S2)值为10~(-13.35);第二阶段均一温度变化范围为120~182℃,平均157.5℃,成矿温度介于185~210℃,盐度介于1.24~7.14wt%Na Cl,平均4.95wt%Na Cl,pH值5.73,呈现出弱碱性,Eh值-0.0775,表现出弱还原性,f _(O2)值为10~(-50.66),f_(CO2)值为2.687,f_(S2)值为10~(-13.36);第三阶段均一温度变化范围为125~170℃,平均150.0℃,成矿温度介于183~201℃,盐度介于3.53~6.17 wt%Na Cl,平均4.66wt%Na Cl,pH值5.73,呈现出弱碱性,Eh值-0.0596,表现出弱还原性,f_(O2)值为10~(-51.47),f_(CO2)值为3.521,f_(S2)值为10~(-13.55);第四阶段均一温度变化范围为95~153℃,平均132.6℃,成矿温度介于162~186℃,pH值5.73,呈现出弱碱性,Eh值-0.073,表现出弱还原性,f_(O2)值为10~(-54.23),f_(CO2)值为3.609,f _(S2)值为10~(-14.05)。通过CO_2-H_2O包裹体测得成矿压力值介与293.1~505.8 bar,平均391.6 bar,对应成矿深度为1.11~1.91km。成矿流体密度值介于0.936-0.982g/cm~3,各成矿阶段密度无明显变化。同位素证据表明,矿质来源于壳源,介质水来源于变质水与大气降水的相互混合。金主要以Au(HS)_2~-的形式进行迁移,锑主要以硫络合物HSb_2S_4~-的形式迁移,钨主要以WO_4~(2-)和HWO_4~-的形式进行迁移,金、锑、钨沉淀的机制是温度的降低,除此之外,钨的沉淀还受第一阶段pH值降低的影响,且温度的降低可能与多种因素有关。
[Abstract]:Woxi gold-antimony-tungsten deposit is located in western Hunan, located at the turning point of Xuefeng structural belt. The deposit occurs in the late Proterozoic turbidite strata of the Madiyi formation of Banxi Group in the late Proterozoic and is obviously controlled by strata and structures. It is well known for its industrial grade of gold, antimony and tungsten, and is a famous large gold-antimony-tungsten deposit in China. The ore body is divided into stratiform ore body and vein ore body, the main ore minerals are natural gold, stibnite and scheelite, and the alteration types of surrounding rock are mainly fading, pyrite and silicification. On the basis of previous studies, the fluid inclusions are used to study the ore-forming fluids. Samples of quartz, scheelite and calcite at different stages are collected for laboratory observation, description, testing and calculation. The main conclusions are as follows: the fluid inclusions mainly consist of two types: s / H _ 2O inclusions and CO_2-H_2O inclusions, with H _ 2O inclusions as the main inclusions. The metallogenic process consists of four stages. In the first stage, the homogenization temperature ranges from 117 to 185 鈩，

本文编号：1859641