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山东省玲珑金矿矿床成因研究
Study on the Genesis of Ling Long Gold Deposit in Shandong Province
【作者】 赵泳越;
【导师】 李碧乐;
【作者基本信息】 吉林大学 , 矿物学、岩石学、矿床学, 2012, 硕士
【摘要】 玲珑金矿区位于山东省胶东半岛西北部,招远市和莱州市的交界处。构造位置处于华北地台胶辽地盾的胶北隆起区西北部,西侧与沂沐大断裂毗邻。玲珑金矿开发较早,始建于1962年,属超大型金矿床。区域内地层出露简单而构造和岩浆活动强烈。玲珑花岗岩是玲珑金矿的主要容矿围岩。岩石地球化学分析表明,玲珑花岗岩体SiO2含量平均值为72.13%。K2O+Na2O=8.42%~10.1%,平均值为8.96%;K2O/Na2O=0.75~1.30,平均值为1.07,属于富钾型花岗岩。A/CNK为0.72~1.04之间,平均值为0.92,属于准铝质至弱过铝质的S型花岗岩。Sr含量(Sr>770μg/g);Y含量(Y<7.64μg/g)Yb含量(Yb<0.5μg/g);上述稀土配分模式特征与埃达克岩类似。锆石LA-ICP-MS U-Pb年龄显示玲珑花岗岩体成岩年龄为158.53±0.79Ma,MSWD=0.13,为晚侏罗世。玲珑花岗岩体的源区物质来源于晚太古代和古元古代地壳,形成于太平洋板块强烈俯冲引起的大陆弧伸展环境。玲珑金矿床严格受NE-NNE向断裂构造控制,且分布在区域性破头青断裂下盘的次级韧-脆性剪切断裂带中,这些矿脉平面上近平行或雁行状排列,剖面上呈共轭形产出,矿脉呈群聚集出现,脉群走向一般是35-70°,以NW倾向为主,但是破头青断裂附近的脉群浅部呈现SE倾向,而深部转为NW倾向,在各脉群内部及相邻脉群之间,矿脉呈十分明显的穿插、交汇、分支、绳结式和结环式复合现象。容矿断裂构造成矿期前表现为左旋压扭,成矿期表现为右旋张扭特征。玲珑花岗岩是主要的赋矿围岩,矿区深部可见容矿的郭家岭花岗岩。矿物矿石主要有黄铁矿、黄铜矿、方铅矿、闪锌矿、金银矿、自然金和少量菱铁矿等。围岩蚀变主要有绢云母化、硅化、黄铁绢英岩化、钾化、碳酸盐化和绿泥石化等,其中金矿化与黄铁绢英岩化和硅化关系密切。流体包裹体为含CO2包裹体和气液两相包裹体,气相成分均以普遍含CO2、H2O和少量N2为特征。成矿流体具有低盐度(0.83-5.247wt%NaCl),低密度(0.69~0.92g/cm3)的特点,成矿均一温度为170-340℃,成矿压力为58-128MPa,成矿深度为6.13-9.42km。玲珑金矿的C、H、O同位素综合研究分析表明,成矿的流体以幔源流体为主,成矿晚期有大气降水的加入;通过对玲珑金矿的铅同位素和胶东群、中生代花岗岩的分析,推测成矿物质主要来源于地幔,下地壳提供部分矿质。燕山早期强烈的俯冲作用导致深俯冲带之上远离海沟的中国东部大陆一侧造山带发生强烈伸展和岩石圈减薄,引发大规模的底侵作用。造成玲珑花岗岩和随后的郭家岭花岗岩的侵位。燕山晚期太平洋板块的持续俯冲使得大陆弧一侧持续伸展,在100~120Ma期间岩石圈减薄至最高峰,引起大规模的幔源岩浆和大规模的金成矿作用的发生,玲珑金矿即为这期构造活动的产物。确定其成因类型为典型的中温热液脉型金矿床。
【Abstract】 The Linglong gold deposit located in the Northwest of Shandong Peninsula inShandong Province, the junction of Zhaoyuan and Laizhou. The sructural position is innorthwest of uplift area which is in the Jiaoliao shield,the North China platform, and thewest is adjacent to Yi Mu large faults.The Strata of the area is exposed relatively simply,but the tectonic and magmatic activity are strong. In this paper, we discuss the genesis andmineralization mechanism on the basis of comprehension studying the regional geologicalbackground, geological features, geological congditions, physical and chemical conditionsand ore source.Linglong granites is the wall rock of Linglong gold deposits. Rock geochemicalanalyzes show that the average content of SiO2is about72.13%. K2O+Na2O=8.42%~10.1%, an average of8.96%; K2O/Na2O=0.75~1.30, an average of1.07.It belongs toPotassium-rich granites. A/CNK=0.72~1.04, an average of0.92; From above, it belongs tometaluminous to weakly peraluminous and S-type granites. Sr>770μg/g, Y<7.64μg/gand Yb<0.5μg/g; The above REE patterns characteristics similar to the adakite.ZirconLA-ICP-MS U-Pb dating shows that the age of Linglong granites is about158.53±0.79Ma,MSWD=0.13, belongs to the late Jurassic. Linglong granites source-material comes fromthe Late-Archean and Paleoproterozoic crust.The granites burn from strong subduction ofthe Pacific plate caused continental arcextensional environment.The gold deposits are strictly controlled by the NE-NNE faults, and distributed in thesub-ductile-brittle shear zones. These veins were nearly parallel or echelon arrangement,and profile was conjugate-shaped output. The veins trend is generally35-70°and mainlyNW tendency. But the veinlets near the fractures are superficial to show the SE tendency,deep into the NW tendency. Between the veins group and the adjacent vein swarm, the veins was obvious interspersed intersection, branch, knot type and knot ring compoundphenomenon. Fault structure of the ore mineralization of the performance is L-pressuretorsion, mineralization of the performance characteristics is dextral transtensional. TheLinglong granites is the main ore-wall rock, from the deep mining area, it is possible tosee Guojialing granites.Mineral ores are mainly pyrite, chalcopyrite, galena, sphalerite, gold and silver ore,natural gold and a small amount of siderite. The wall rock alteration is mainlysericitization, silicification, pyrite phyllic, potassic, carbonate and chlorite and so, inwhich gold mineralization is closely related withpyrite phyllic alteration and silicification.Fluid inclusions containing CO2inclusions and gas-liquid two-phase inclusions, The gasphase composition are generally containing CO2, H2O and a small amount of N2. Theore-forming fluid has low salinity(0.83-5.247wt%NaCl), low-density(0.69~0.92g/cm3)characteristics, The mineralization uniform temperature is about170-340℃. Ore-formingpressure is about58-128MPa, mineralization is about6.13-9.42km. The C、H、O isotopeanalysis of Linglong gold deposit shows that the main ore-forming fluid is mantle fluid,thelate metallogenic has got some atmospheric water to join.From the analysis of the Pbisotope of Linglong gold deposit、Jiaodong group and Mesozoic granites, we can speculatethat the forming materials are mostly derived from the mantle,lower crust provide part ofthe minerals.The strong subduction of early Yanshanian led to deep subduction zone away fromthetrench above the eastern part of the mainland side of the orogen strong stretchingandlithospheric thinning, and lead to large-scale underplating. It cause the Linglong granitesand subsequent Guojialing granites emplacement. Late Yanshanian, continued subductionof the Pacific plate makes the side of the continental arccontinuous stretch.The Linglong gold deposit is mainly mineralization of quarts-veins. The mainmetallic minerals are pyrite, chalcopyrite, galena, sphalerite and minor siderite, etc. Thereare many types of wall-rock alteration, such as K-fledspar phase, silicification,sericitization and Pyrite phyllic ect. This is typical of mesothermal-type deposits in thealteration assemblage. During100~120Ma, the lithospheric thinning to peak, it cause theoccurrence of large-scale mantle-derived magma and large-scale gold mineralization.Linglong gold deposit is the product of this tectonic activity. From above, we can determine that Linglong gold deposit is the typical type ofMesothermal vein-type gold deposits.
【Key words】 Ore forming fluid; Genetic type of deposits; Mesothermal vein-type gold deposit; Linglong; Shandong;
- 【网络出版投稿人】 吉林大学 【网络出版年期】2012年 10期
- 【分类号】P618.51
- 【被引频次】7
- 【下载频次】583