延边地区小西南岔富金铜矿床的成矿机理:矿物流体包裹体和同位素的制约  

Metallogenic mechanism of the Xiaoxinancha Au-rich Cu deposit in Yanbian area, Jilin Province: Constrains from fluid inclusions and isotope geochemistry

作　　者：门兰静[1] 张馨文 孙景贵[2] 赵俊康 王好均 刘城先[1] MEN Lanjing;ZHANG Xinwen;SUN Jinggui;ZHAO Junkang;WANG Haojun;LIU Chengxian(Changchun Institute of Technology,Changchun 130021,Jilin,China;College of Earth Science,Jilin University,Changchun130061,Jilin,China;Zijin Mining Industry Groups Co.,Ltd.,Xiamen 361009,Fujian,China)

机构地区：[1]长春工程学院,吉林长春130021 [2]吉林大学地球科学学院,吉林长春130061 [3]紫金矿业有限公司,福建厦门361009

出　　处：《中国地质》2018年第3期544-563,共20页Geology in China

基　　金：吉林省科技厅科研基金项目(120160038;120140075);吉林省科技发展计划项目(20180101310JC;20180520086JH);国家自然科学基金项目(40772052)联合资助~~

摘　　要：小西南岔富金铜矿床是中国东部陆缘重要的热液矿床,由不同矿石品位和矿体特征的南山、北山两个矿段组成,矿化形式分别为脉状、细脉浸染状。流体包裹体研究表明:北山矿段均一温度为120~470℃,Ⅰ矿化阶段流体盐度为10.1%~20.0%NaCl eqv,Ⅱ、Ⅲ矿化阶段盐度变化大,为0.4%~45.5%NaCl eqv,流体气相成分为H_2O、CO_2、CH_4,少量N_2。南山矿段均一温度为150~450℃,Ⅰ成矿阶段盐度为4.0%~11.1%NaCl eqv,Ⅱ、Ⅲ矿化阶段盐度随着温度降低盐度逐渐减小,气相成分主要是H_2O、CO_2、CH_4;似斑状角闪花岗闪长岩石英内流体包裹体与南、北山矿段流体显示相近的均一温度范围(150~510℃)和气体成分,盐度4.9%~11.5%NaCl eqv与南山矿段Ⅰ成矿阶段流体相似。流体包裹体的显微测温、氢氧同位素,稀有气体同位素和Pb同位素结果表明南山矿段的成矿过程为幔源中低盐度流体在围岩裂隙中随着温度、压力降低以充填结晶作用为主而成矿;北山矿段成矿过程为幔源中低盐度流体发生沸腾作用后,与地壳流体混合,随后成矿流体以交代方式成矿,晚阶段两个矿区在大气水的混入作用下,北山矿段形成胶黄铁矿石英脉,南山矿段形成纯硫化物脉;似斑状角闪花岗闪长岩内流体包裹体特征反映了初始含矿流体属性,为中低盐度幔源岩浆热流体。The Xiaoxinancha Au-rich Cu deposit is an important hydrothermal deposit in eastern China. The deposit includes twomines, known as the North mine（veinlet-dissemination type） and the South mine（vein type）, which show different ore grades and orebody characteristics. The total homogenization temperatures（Th,total） range from 120 to 470 ℃, and the salinities in the Ⅰmineralization stage and Ⅱ-Ⅲ mineralization stage are 10.1%-20.0% Na Cl eqv and 0.4%-45.5% Na Cl eqv, respectively, with the gas composition consisting mainly of H2O, CO2, CH4 and N2 in the North mine. The South mine fluids yield Th,totalof 150 to 450 ℃,salinities of 4.0%-11.1% NaCl eqv in the Ⅰmineralization stage, and the salinities in theⅡ-Ⅲ mineralization stage decrease with the decreasing temperatures, and the main gas composition consists of H2O, CO2, and CH4. The quartz-hosted fluid inclusions in the hornblende-granodiorite have homogenization temperatures of 150 to 510℃, and salinities of 4.9%-11.5% Na Cl eqv, being similar to those in the North and South mine. The authors hold that the North mine was formed by replacement of fluids which experienced mixing with crustal fluids in the Wudaogou Group after the boiling, whereas the South mine was mainly formed through fillingcrystallization of the initial ore-forming fluids with the decreasing temperatures and pressures, and the ore-forming fluids that involved the meteoric water in the mid-late stage produced melnikovite-quartz veins in the North mine and pure sulfide veins in the South mine. The fluid inclusions in the hornblende-granodiorite possibly reveal initial ore-forming fluid signatures characterized by low-moderate salinity and mantle-derived magmatic fluids.

关 键 词：流体演化 成矿机理 小西南岔富金铜矿床 延边地区 

分 类 号：P618.41[天文地球—矿床学] P618.51[天文地球—地质学]