摘要
驱龙斑岩铜矿是冈底斯成矿带新发现的规模最大的超大型矿床,形成于中新世.原生流体包裹体有5种类型,主成矿阶段均一温度集中于240～650℃之间,盐度变化于0.18%～52.04%之间,明显分为高盐度高密度、低盐度低密度2类.可见含子矿物、液相、气相等包裹体共存现象,且均一温度相近,盐度相差很大,表明成矿流体经历了沸腾过程;氢氧同位素及单矿物微量稀土元素研究表明,成矿物质主要来源于斑岩岩浆体系,而成矿流体主要来源于岩浆水、天然热卤水有关的混合水,且天然热卤水占优势,属NaCl(F)-KCl(F)-C2H6-HCO3-CaSO4型流体.成矿流体总体显示出高温、高盐度、高矿化度、高氧逸度的还原性酸性流体特征,并且富集Na+、K+、F-、Cl-、SO2-4、CO2等成分,以富F-为特征(F-/Cl->1,平均为5.66),这种特殊性质的流体特别有利于Fe2+、Cu2+等元素的迁移,并最终在岩浆期后热液期富集成矿,它是形成驱龙超大型斑岩铜矿床的必要条件;流体减压沸腾及不同性质流体混合作用是促使金属离子沉淀富集的主要机制.对该矿床成矿深度(0.5～2km)进行了探讨,可作为该矿床勘查评价的依据.
The Qulong porphyry copper deposit is the largest recently found in the Gangdise metallogenic belt. It was formed in the Miocene. The original fluid inclusions can be divided into five types according to the compositions of liquid, gas and single minerals The temperature of the main ore-forming phase ranges from 240 to 650 ℃ and the salinity is about 0. 18wt. %-52. 04wt. %. The fluids can be classified into two types including high salinity and high density, low salinity and low density. Daughter mineral inclusions, liquid and gas inclusions are coexistent and their homogeneous temperature is approximate, however salinity is quite different, showing that the fluid underwent the process of boiling. A study of the H and O isotopes and trace and rare elements of a single mineral indicates that the mineralization substance comes from the system of porphyry magma and fluid belonging to the NaCl（F）-KCl（F）-C2H6-HCO3-CaSO4 type fluid, which comes from magma and natural hot-brine. The fluid is characteristically reducing and acid, with high temperature, high salinity, high miner alization degree, and high oxygen fugacity. The fluid has high concentrations of Na^＋ , K^＋, Cl^-, SO4^2-, CO2 etc. , with high F^- （F^-/Cl^-〉1, average 5. 66）, which was good for the transfer of F^2＋ and Cu^2＋ , finally concentrated and formed the deposit, and is the necessary condition for the Qulong super-large porphyry copper deposit to form. Decompression and the mixing of different quality fluids is the main mechanism for the depositing of metal ions. The mineralizated depth is also discussed and could be regarded as the prospecting base of mineral deposit.
出处
《地球科学（中国地质大学学报）》
EI
CAS
CSCD
北大核心
2006年第3期349-354,共6页
Earth Science-Journal of China University of Geosciences
基金
国土资源部"新一轮国土资源大调查"重大项目(No.200210200001)
国家自然科学基金项目(No.40542008).
关键词
驱龙
超大型斑岩铜矿
成矿流体
成矿控制
必要条件.
Qulong
super-large porphyry copper deposit
ore-forming fluid
ore-controlling
necessary condition.
