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、CO_(2)包裹体、CO_(2)-H2O包裹体,以富含CO_(2)-H2O包裹体为特征。CO_(2)-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CO_(2)的高压、中高温、中低盐度的H2O-Na Cl-CO_(2)的流体。加热时,富H2O相的CO_(2)-H2O包裹体完全均一到H2O相,富CO_(2)相的CO_(2)-H2O包裹体完全均一到CO_(2)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,CO_(2)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,CO_(2)inclusions and CO_(2)-H2 O inclusions,among which the CO_(2)-H2 O inclusion is the main type.The ore-forming temperature was283.1-382.0℃and the salinity of the CO_(2)-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-CO_(2)system of middle-high temperature with high-CO_(2)content and low to moderate salinity.When heated,the H2O-rich CO_(2)-H2 O inclusions were homogenized into H2 O phase,and the CO_(2)-rich CO_(2)-H2 O inclusions were homogenized into the CO_(2)phase.Moreover,they have the same homogenization temperature and pressure.When the immiscibility effect of the fluid occurred,a large amount of CO_(2)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.
作者
邓丹莉
李葆华
高昆丽
李表鹏
DENG Dan-li;LI Bao-hua;GAO Kun-li;LI Biao-peng(College of Earth Sciences,Chengdu University of Technology,Chengdu,Sichuan 610059)
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
