投稿时间：2015-06-10
修订日期：2016-01-15
网络发布日期：2016-04-29
中文摘要:洋灰洞子铜矿床位于延边-东宁成矿带,兴凯-延边岩浆构造带北端。矿床发育在花岗闪长斑岩与三叠系黄松群阎王殿组浅变质岩系接触带内侧的角砾岩带内,矿体多呈透镜状和脉状产出。矿床地质和岩相学特征研究表明:围岩蚀变主要是黑云母化、绢云母化、硅化、绿泥石化、绿帘石化及碳酸盐化;蚀变分带特征明显,以岩体为中心向外依次发育钾硅酸盐化带、绢英岩化带和青磐岩化带。矿石矿物主要是黄铜矿、黄铁矿和磁黄铁矿,其次是毒砂、辉钼矿、闪锌矿、方铅矿等。成矿过程可初步划分为4个阶段,从早到晚依次为:(Ⅰ)石英-黄铁矿-毒砂阶段;(Ⅱ)石英-磁黄铁矿-辉钼矿阶段;(Ⅲ)石英-多金属硫化物阶段和(Ⅳ)石英-碳酸盐阶段。流体包裹体类型有富液相(WL)、富气相(WV)、纯液相(L)和纯气相(V)以及含子晶三相(S)包裹体;其中Ⅰ阶段发育富液相包裹体;Ⅱ阶段发育富液相和含子矿物三相包裹体;Ⅲ阶段发育气液两相、纯液相和纯气相以及少量含子晶三相包裹体,呈孤立和群体分布;Ⅳ阶段主要是富液相和纯液相包裹体。流体包裹体均一温度分别为380~417℃、304~368℃、171~310℃和116~189℃,与划分的4个成矿阶段相对应。Ⅰ、Ⅱ阶段包裹体的w(NaCleq)分别为4.63%~14.52%和5.09%~14.63%;Ⅲ阶段包裹体的w(NaCleq)分布在1.73%~10.37%和13.44%~15.35%两个区间;Ⅳ阶段包裹体的w(NaCleq)为0.87%~9.08%。早阶段包裹体气相成分主要为H2O,含少量CO2;主成矿阶段以H2O为主,含少量CH4;晚阶段只有H2O;指示伴随着温度降低,成矿过程由含CO2的水盐体系逐渐演化为含CH4的水盐体系。结合与成矿密切相关的花岗闪长斑岩的斑晶石英和各不同成矿阶段硫化物石英脉的石英H-O同位素及矿石矿物Pb同位素特征,认为成矿流体来源于花岗质岩浆作用或是出溶流体,成矿物质来源于深部岩浆。成岩成矿过程经历了花岗质岩浆上升侵位→流体出溶与含矿流体形成→隐爆作用→成矿流体与大气水混合等过程,并先后形成以黄铁矿化为主的蚀变岩和以铜为主的多金属硫化物石英脉、石英-碳酸盐脉。综合研究认为洋灰洞子铜矿床属于斑岩型铜矿床。
Abstract:The Yanghuidongzi copper deposit is located in the Yanbian-Dongning metallogenic belt along the northern part of Xingkai-Yanbian magmatic-tectonic zone. The orebodies are mainly hosted in breccia zone of the inner contact zone between granodioritic porphyry and Triassic metamorphic rocks of Yanwangdian Formation in Huangsong Group, which are mainly lenticular and veinlike in shape. Detailed studies of geological features of ore deposit geology and petrography indicate that the wall-rock alterations include mainly biotitization, sericitization, silicification, chloritization, epidotization and carbonation, and the alteration zoning from the lithosome to the wall rock is in order of potassium silicate zone, phyllic zone and propylitization zone. The ore minerals are mainly chalcopyrite, pyrite and pyrrhotite, subordinately arsenopyrite, molybdenite, sphalerite and galena. The ore-forming process can be divided into four stages:(Ⅰ) quartz-pyrite-arsenopyrite stage; (Ⅱ) quartz-pyrrhotite-molybdenite stage; (Ⅲ) quartz-polymetallic sulfides stage; and (Ⅳ) quartz-carbonate stage. The fluid inclusions in the Yanghuidongzi copper deposit are mainly liquid-rich inclusion (WL-type), vapor-rich inclusion (WV-type), pure liquid inclusion (L-type), pure vapor inclusion (V-type) and daughter-minerals bearing three-phase inclusion (S-type). The Ⅰstage quartz contains WL-type fluid inclusions, the Ⅱ stage quartz contains WL-type and very small S-type fluid inclusions; the Ⅲ stage quartz contains WL-type, WV-type, L-type, V-type and S-type fluid inclusions, which occurs in isolated form or in group; and the Ⅳ stage quartz contains WL-type and L-type fluid inclusions. The homogeneous temperature of the fluid inclusions from Ⅰ to Ⅳ stage are 380~417℃, 304~368℃, 171~310℃ and 116~189℃, respectively, which correspond to the four ore-forming stages. The w(NaCleq) of fluid inclusions from Ⅰ and Ⅱ stage are 4.63%~14.5% and 5.09%~14.63%; the w(NaCleq) of fluid inclusions from Ⅲ stage could be divided into two groups:1.73%~10.37% and 13.44%~15.35%; the w(NaCleq) of Ⅳ stage is 0.87%~9.08%. Laser Raman spectroscopic analysis indicates that the gas components of fluid inclusions at the early stage is dominated by H2O and a little CO2, while the gas components of fluid inclusions from the main ore-forming stage is dominated by H2O and a little CH4; the component of fluid inclusions from the late stage is only H2O, suggesting that the ore-forming process evolved from the CO2-bearing salt-water system to CH4-bearing salt-water system gradually with decreasing temperature. The study of H-O isotope of quartz from phenocrysts of granodioritic porphyry and from sulfide quartz veins of every ore-forming stage and Pb isotope of sulfides show that the primary ore-forming fluid was mainly derived from granodioritic magma or was probably the product of exsolved fluid, and ore material was derived from deep magma. The ore-forming process experienced the emplacement of granitoid magmas, fluid exsolution, the formation of ore-bearing fluid, cryptoexplosion and the mixing of ore-forming fluid and meteoric water, which resulted in the formation of pyritization-dominated altered rock, copper-dominated sulfide quartz vein and quartz-carbonate vein in succession. Comparative studies suggest that the Yanghuidongzi copper deposit belongs to the porphyry copper type.
keywords:geochemistry fluid inclusion stable isotope ore genesis Yanghuidongzi copper deposit eastern Heilongjiang Province
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中图分类号：P618.41
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基金项目:本文得到国家自然科学基金(编号:41390443;41172072)资助
引用文本：
祝浚泉,孙景贵,门兰静,古阿雷,陈延峻,明珠,赵世峰,闫佳.2016.黑龙江省东部洋灰洞子铜矿床成矿机理: 矿化蚀变、流体包裹体和稳定同位素示踪[J].矿床地质,35(2):365~380ZHU JunQuan,SUN JingGui,MEN LanJing,GU ALei,CHEN YanJun,MING Zhu,ZHAO ShiFeng,YAN Jia.2016.Metallogenic mechanism of Yanghuidongzi copper deposit in eastern Heilongjiang Province: Mineralization-alteration, fluid inclusions and stable isotope tracing[J].Mineral Deposits35(2):365~380
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