滇西北衙斑岩型金多金属矿床成矿流体特征及其演化  

The characteristics and evolution of the ore-forming fluids in the Beiya porphyry Au-polymetallic deposit,western Yunnan

作　　者：王建华[1] 李文昌[1,2] 王可勇[3] 尹光候 吴松[1] 姜文涛[1] 

机构地区：[1]昆明理工大学国土资源工程学院,昆明650093 [2]云南省地质调查局,昆明650051 [3]吉林大学地球科学学院,长春130061

出　　处：《岩石学报》2015年第11期3269-3280,共12页Acta Petrologica Sinica

基　　金：国家重点基础研究发展计划项目(2015CB452605);云南省科技创新人才计划-科技领军人才培养项目(2013HA001);中国地质调查局地质调查工作项目(12120114013501)联合资助

摘　　要：北衙超大型金多金属矿床位于扬子陆块西缘与三江特提斯造山带的结合部位。本文通过对北衙矿区内的斑岩体石英斑晶、斑岩型矿化、矽卡岩矿化中的矽卡岩及外围似层状热液型铅锌银矿化的岩(矿)石中发育的流体包裹体进行了系统研究,发现北衙矿区内主要发育CO2、富CO2、含CO2、含子矿物三相、富气相水溶液及气液两相水溶液包裹体六类流体包裹体;与斑岩型矿化有关的成矿流体为中-高温Na Cl-H2O-CO2体系热液,矽卡岩矿化相关成矿流体为一种高温的Na Cl-H2O及Na Cl-H2O-CO2体系热液,而外围似层状铅锌银矿化相关的成矿流体则为中温的Na Cl-H2O-CO2体系热液。对比分析表明,矽卡岩矿化中的矽卡岩矿物(以绿帘石类矿物为主)形成较早,其中发育富气相的流体包裹体,可以推断岩浆侵位后先分异出富水蒸气的流体,此后CO2才从成矿流体中大量分异。斑岩型矿化及外围地层中似层状铅锌银矿化脉体中发育的流体包裹体与斑岩体石英斑晶内发育的流体包裹体组合类型基本一致,表明成矿流体主要来自斑岩体结晶分异出的岩浆热液。流体包裹体研究表明,北衙金多金属矿区内的矽卡岩型(金铜铁)、斑岩型(铜金钼)及外围碳酸盐岩等地层中的似层状热液型(铅锌银)矿床系列为与富碱斑岩体侵位活动有关的,由岩浆分异热液并逐渐演化形成的斑岩型金-铁铜-铅锌(银)多金属成矿系统。The Beiya super-large gold deposit is located in the junction zone of the ‘Sanjiang＇Tethys orogenic belt and Yangtze plate in SW China. This systematic study on fluid inclusion developed in the quartz phenocryst of porphyries and mainly mineralization（ i. e. porphyry-,skarn-,and layer-like epithermal-） occur in the Beiya deposit indicate that there are six types of fluid inclusions exist in the study area named： Ⅰ CO2 fluid inclusions; Ⅱ CO2-rich fluid inclusions; Ⅲ CO2-bearing fluid inclusions; Ⅳ halite-bearing three-phase fluid inclusions; Ⅴ vapor-rich fluid inclusions and Ⅵ aqueous two-phase fluid inclusions; the ore forming fluids responsible for the formations of porphyry-, skarn-, and layer-like polymetallic epithermal-mineralizaion are medium to high temperature Na Cl-H2O-CO2 type solutions,high temperature Na Cl-H2O-CO2 with Na Cl-H2 O type solutions and medium temperature Na Cl-H2O-CO2 type solutions respectively. The presence of vapor-rich fluid inclusions in the skarn demonstrates that vapor-rich ore forming fluids were differentiated from magma after the emplacement of the porphyries,and then came to the abundant of fluids rich in CO2. The fact that the groups of fluid inclusions in the porphyry-and layer-like polymetallic epithermal veins are almost the same to the ones in the quartz phenocrysts of porphyries indicates that the ore forming fluids related to the two types of mineralization came from the magmatic hydrothermal which differentiated from the central porphyries. This fluid inclusion study also illustrates that the three main types of mineralization resulted from the evolution of the ore forming fluids differentiated from the magma which produced the alkalinerich porphyries in Beiya constitute a porphyry Au-Fe-Cu-Pb-Zn-Ag polymetallic metallogenic system.

关 键 词：流体包裹体 斑岩型 金多金属成矿系统 北衙金矿 滇西 

分 类 号：P618.51[天文地球—矿床学]