摘要
云南大坪金矿床是产于闪长岩中的石英脉型金矿床,矿体形态呈脉状,明显受断裂构造控制。成矿阶段可分为：早期成矿阶段（白钨矿石英脉）、主成矿阶段（硫化物石英脉）和晚成矿阶段（碳酸盐石英脉）。石英脉中的流体包裹体分为H2O包裹体、CO2包裹体、CO2-H2O包裹体,以富含CO2-H2O包裹体为特征。CO2-H2O包裹体的完全均一温度为283.1-382.0℃,盐度为（4.44-11.33）wt%Na Cleqv,计算的均一压力为151.2-261.5MPa,相应的成矿深度为10.272-12.649km,显示出该矿的成矿流体是一种富含CO2的高压、中高温、中低盐度的H2O-Na Cl-CO2的流体。加热时,富H2O相的CO2-H2O包裹体完全均一到H2O相,富CO2相的CO2-H2O包裹体完全均一到CO2相,而且二者的完全均一温度和压力一致,说明流体发生了不混溶作用,CO2的溶离使成矿流体的p H值升高,氧逸度降低,从而导致Au溶解度降低,并造成金沉淀成矿。大坪金矿床属于深成中高温热液石英脉型金矿床。
The Daping gold deposit is of quartz vein type,which is hosted by diorite. Its ore bodies show a form of vein,obviously controlled by faults. Mineralization epochs of this deposit can be divided into three stages： the early stage（ scheelite- bearing quartz vein）,the major stage（ massive polymetallic sulphide in auriferous quartz vein） and the 1ate stage（ carbonate- quartz）. The fluid inclusions in quartz are divided into three categories： H2 O inclusions,CO2 inclusions and CO2- H2 O inclusions,among which the CO2- H2 O inclusion is the main type. The ore- forming temperature was283. 1 - 382. 0℃ and the salinity of the CO2- H2 O inclusion was 4. 44% - 11. 33%,the ore- forming pressure was in the range of 151. 2 - 261. 5MPa with corresponding metallogenic depths of about 10. 272 - 12. 649 km. The fluid inclusion characteristics indicate that the ore- forming fluid of the Daping mine is a H2O- NaC l- CO2 system of middle- high temperature with high- CO2 content and low to moderate salinity. When heated,the H2O-rich CO2- H2 O inclusions were homogenized into H2 O phase,and the CO2- rich CO2- H2 O inclusions were homogenized into the CO2 phase. Moreover,they have the same homogenization temperature and pressure. When the immiscibility effect of the fluid occurred,a large amount of CO2 overflowed,the fugacity of O2 decreased,and p H increased. It led to the reduction of the solubility of gold in ore- forming hydrothermal fluid to the rapid precipitation of gold,and to the formation of deposits. The Daping gold deposit belongs to the middle- high temperature and high pressure deposits.
出处
《地质与勘探》
CAS
CSCD
北大核心
2016年第5期865-873,共9页
Geology and Exploration
基金
国家自然科学基金项目“甘肃干沙河稀土矿床碱性岩浆-流体演化过程研究”(批准号:41372094)资助
关键词
成矿流体
包裹体
不混溶
大坪金矿床
云南
ore-forming fluids
inclusions
immiscible fluids
Daping gold deposit
Yunnan Province
