永平铜多金属矿床地质与地球化学特征
发布时间：2018-08-31 12:49
【摘要】：永平铜多金属矿床位于华南板块十杭断裂带南侧,是区内典型的与晚侏罗世二长花岗斑岩类有关的斑岩-矽卡岩矿床。本文在前人研究工作的基础上,展开了岩石地球化学、锆石U-Pb测年、流体包裹体和稳定同位素研究,取得的成果如下:(1)永平矿区范围内主要存在斑岩型矿化和矽卡岩矿化两种矿化类型。斑岩型钼矿化主要发育在岩体内部及岩体与围岩的接触带,形成十字头钼矿体;矽卡岩铜矿化主要发育在岩体外围的碳酸盐岩地层的层间破碎带中,形成天排山铜矿体。钼矿体和铜矿体紧密相连,两者的地质概况也大致相同。(2)对永平花岗质岩体进行了主微量、锆石U-Pb测年等方面的研究。永平花岗质岩石定名为二长花岗斑岩,具有高硅、富碱的特点,样品的落点主要位于准铝质靠近过铝质的区域,说明为准铝质-过铝质花岗岩类。Na2O含量变化较大,K2O/Na2O较高,铝饱和指数(ASI)为0.97~1.38,整体表现为I-S过渡类型花岗岩的特征。轻稀土元素(LREE)强富集,大离子亲石元素(Rb、Ba、U、Th、K、Pb)富集,相当于原始地幔的数百倍,高场强元素(Nb、Ta、Ti)亏损,表明二长花岗斑岩形成于与岛弧有关的构造环境中。锆石U-Pb定年获得岩体侵位时代为155.7±2.7Ma,属于晚侏罗世岩浆活动的产物,研究区在180~170Ma是大陆弧环境,160~150Ma为大陆弧和同碰撞构造环境的过渡,之后进入碰撞造山阶段。(3)流体包裹体研究结果表明,永平矽卡岩铜矿化与斑岩型钼矿化成矿流体具有相似的演化特征,都是由高温向中低温演化,且是一个自然冷却的过程,两者都经历的石英-硫化物阶段温度和盐度的区间范围也具有一定的重合。激光拉曼测试结果也显示二者流体包裹体中具有相似的气相成分(以CO2和H2O为主),成矿流体体系同属于CO2-H2O-Na Cl体系。(4)硫同位素测试分析结果显示,矿石金属硫化物的δ34S值介于-0.2‰~+1.9‰之间,位于零值附近,这表明成矿物质硫源主要来自于深部的岩浆。(5)结合矿区地质特征,认为永平铜多金属矿床是与晚侏罗世的花岗质岩浆关系密切的岩浆热液型矿床,十字头岩体即为岩浆侵位中心,构成以斑岩型钼矿在内部,矽卡岩型铜钨铅锌矿在外围的成矿分带。十字头钼矿体与天排山铜矿体一起构成了永平斑岩型-矽卡岩型铜多金属矿床。
[Abstract]:Yongping copper polymetallic deposit is a typical porphyry skarn deposit related to late Jurassic Erchanggranitic porphyry in the south of the Shihang fault zone of South China plate. On the basis of previous studies, this paper has carried out geochemistry, zircon U-Pb dating, fluid inclusions and stable isotopes. The results are as follows: (1) there are two types of porphyry mineralization and skarn mineralization in Yongping mining area. Porphyry molybdenum mineralization mainly developed in the contact zone between rock mass and surrounding rock to form cross head molybdenum orebody, while skarn copper mineralization mainly developed in the interlayer fracture zone of carbonate strata around the rock mass, forming Tianpaishan copper deposit body. The molybdenum ore body and the copper ore body are closely connected, and their geological profiles are similar. (2) the main trace amount and zircon U-Pb dating of the Yongping granitic rock body have been studied. Yongping granitic rock is named as Erchang granitic porphyry, which has the characteristics of high silicon and rich alkali. The sample's falling point is mainly located in the area of quasi-aluminite near peraluminous, which indicates that the content of quasi-aluminite-peraluminous granitoids has a great change in content of K _ 2O / Na _ 2O, and the content of K _ 2O / Na _ 2O is relatively high. The aluminum saturation index (ASI) is 0.97 ~ 1.38, which is characterized by I-S transition type granite. The (LREE) enrichment of light rare earth elements and the enrichment of large ion lithophile elements (Rb,Ba,U,Th,K,Pb) are hundreds of times as much as those of the primitive mantle. The depletion of high field strength elements (Nb,Ta,Ti) indicates that the Erchang granitic porphyry was formed in a tectonic environment related to island arc. Zircon U-Pb dating obtained an emplacement age of 155.7 卤2.7 Ma.It is the product of late Jurassic magmatism. The study area is a transition between continental arc and syncollision tectonic environment in 180~170Ma, which is a continental arc environment (160 ~ 150Ma). The results of fluid inclusion study show that the ore-forming fluid of Yongping skarn copper deposit and porphyry molybdenum mineralization have similar evolution characteristics, both of which are from high temperature to middle low temperature, and are a natural cooling process. The range of temperature and salinity in quartz-sulfide stage is also consistent. Laser Raman measurements also show that there are similar gas compositions (mainly CO2 and H2O) in the fluid inclusions, and the ore-forming fluid systems belong to the CO2-H2O-Na Cl system. (4) the sulfur isotope analysis results show that the ore-forming fluid system belongs to the CO2-H2O-Na Cl system. The 未 34S values of ore metal sulfides range from -0.2 鈥，
本文编号：2215036
[Abstract]:Yongping copper polymetallic deposit is a typical porphyry skarn deposit related to late Jurassic Erchanggranitic porphyry in the south of the Shihang fault zone of South China plate. On the basis of previous studies, this paper has carried out geochemistry, zircon U-Pb dating, fluid inclusions and stable isotopes. The results are as follows: (1) there are two types of porphyry mineralization and skarn mineralization in Yongping mining area. Porphyry molybdenum mineralization mainly developed in the contact zone between rock mass and surrounding rock to form cross head molybdenum orebody, while skarn copper mineralization mainly developed in the interlayer fracture zone of carbonate strata around the rock mass, forming Tianpaishan copper deposit body. The molybdenum ore body and the copper ore body are closely connected, and their geological profiles are similar. (2) the main trace amount and zircon U-Pb dating of the Yongping granitic rock body have been studied. Yongping granitic rock is named as Erchang granitic porphyry, which has the characteristics of high silicon and rich alkali. The sample's falling point is mainly located in the area of quasi-aluminite near peraluminous, which indicates that the content of quasi-aluminite-peraluminous granitoids has a great change in content of K _ 2O / Na _ 2O, and the content of K _ 2O / Na _ 2O is relatively high. The aluminum saturation index (ASI) is 0.97 ~ 1.38, which is characterized by I-S transition type granite. The (LREE) enrichment of light rare earth elements and the enrichment of large ion lithophile elements (Rb,Ba,U,Th,K,Pb) are hundreds of times as much as those of the primitive mantle. The depletion of high field strength elements (Nb,Ta,Ti) indicates that the Erchang granitic porphyry was formed in a tectonic environment related to island arc. Zircon U-Pb dating obtained an emplacement age of 155.7 卤2.7 Ma.It is the product of late Jurassic magmatism. The study area is a transition between continental arc and syncollision tectonic environment in 180~170Ma, which is a continental arc environment (160 ~ 150Ma). The results of fluid inclusion study show that the ore-forming fluid of Yongping skarn copper deposit and porphyry molybdenum mineralization have similar evolution characteristics, both of which are from high temperature to middle low temperature, and are a natural cooling process. The range of temperature and salinity in quartz-sulfide stage is also consistent. Laser Raman measurements also show that there are similar gas compositions (mainly CO2 and H2O) in the fluid inclusions, and the ore-forming fluid systems belong to the CO2-H2O-Na Cl system. (4) the sulfur isotope analysis results show that the ore-forming fluid system belongs to the CO2-H2O-Na Cl system. The 未 34S values of ore metal sulfides range from -0.2 鈥，
本文编号：2215036
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