摘要
冈底斯是我国重要的斑岩型铜矿带,东段已发现一系列大型-超大型斑岩矿床且研究程度较高,而西段仅发现朱诺一例大型斑岩铜矿床,且研究程度较低,这不利于冈底斯东西段的对比研究。本文对朱诺矿床进行了流体包裹体岩相学研究、包裹体测温及激光拉曼光谱分析,并与冈底斯东段的驱龙斑岩矿床开展了对比。研究表明朱诺矿床共发育四种类型包裹体,分别为富液相气液两相水溶液包裹体（LV）、富气相气液两相水溶液包裹体（VL）、含子晶多相（LVH）及富CO2三相（C）包裹体。从成矿早期到晚期（即由A脉向B脉至D脉阶段）,包裹体均一温度集中分布在350～550℃、250～350℃、250～300℃,盐度为5%～55%NaCleqv、5%～40%NaCleqv、2%～10%NaCleqv,显示包裹体均一温度及盐度呈递减趋势。而在B脉阶段,在显微镜下同一视域内可见不同类型（LV、VL、LVH）的包裹体共存,并且具有相似的均一温度而盐度变化较大特征,这是流体沸腾的明显标志,预示压力的降低及硫化物的沉淀。通过压力估算得到朱诺矿床A、B、D脉阶段的成矿深度分别为2.9km、2.7km、2.3km。通过与驱龙铜矿的对比,朱诺矿床硬石膏发育相对较弱,预示成矿流体氧逸度相对驱龙矿床低,此外二者在包裹体类型、温度、盐度等方面相似,但朱诺的成矿深度比驱龙的略浅,这在冈底斯西段总体剥蚀程度相对东段低的背景下是有利于矿床的寻找。
The Gangdese porphyry copper belt is one of the most important copper belts in China. Many large and super-large porphyry Cu-Mo（-Au） deposits have been discovered in the eastern part but only one large porphyry Cu deposit at Zhunuo was found in the western part of the belt. The metallogenesis of porphyry deposit in the western part of Gangdese belt is poorly constrained,which is not helpful for studying the difference of ore-forming condition and metallogenesis between western and eastern belt. Therefore,we studied the characteristics of the petrography,microthermometry,and Raman spectrum of fluid inclusions（ FIs） of the Zhunuo porphyry copper deposit and compared them with the Qulong deposit in the eastern part of the Gangdese belt. Four types of fluid inclusions（ FIs） are distinguished in this study based on petrographic and microthermometric criteria,i. e. rich vapor phase aqueous,rich liquid phase aqueous,rich CO2 and daughter mineral-bearing fluid inclusions. The inclusions from A vein through B vein to D vein have homogenization temperatures ranging from 350 ～ 550℃,250 ～ 350℃,250 ～ 300℃ and salinities ranging from 5% ～ 55%NaC leqv,5% ～ 40% NaC leqv,and 2% ～ 10% NaC leqv,respectively,which reveals that the temperature and salinity decreased from early to late stage. At B vein stage,different types of FIs were observed in one field of vision and show a similar temperature and wideranged salinity,indicating fluid boiling and decrease of pressure which are benefit for the minerals precipitation. The pressure estimation in Zhunuo deposit shows that the depth is 2. 9km,2. 7km,and 2. 3km from early stage to the late stage. The types,temperatures,and salinities of FIs for the Zhunuo deposit are similar to those for the Qulong deposit. However,the ore-forming depth at Zhunuo is relatively lower than that at Qulong,which is helpful for the prospecting in the western part of the Gangdese belt because the erosion degree of the western part is lower than that of the eastern part. In additio
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
2015年第5期1335-1347,共13页
Acta Petrologica Sinica
基金
国家自然科学基金项目(41302063)
中国地质调查局工作项目(1212011220927)
教育部长江学者和创新团队发展计划(IRT14R56)
教育部博士点基金项目
北京高等学校青年英才计划联合资助
