摘要
胶东地区的金矿找矿不断取得新突破,已成为世界第三大金矿集区。本文系统总结了胶东金矿床的空间分布、构造控矿和矿化蚀变等基本特征,分析了存在的主要争议问题。总结指出,胶东金矿床分布于胶西北、栖蓬福和牟乳3个金矿床集中区,有三山岛、焦家、招平、西林—陡崖和金牛山5条主要控矿断裂带。赋矿地质体主要为侏罗纪玲珑型花岗岩、白垩纪郭家岭型花岗岩和新太古代—古元古代变质岩系,白垩纪莱阳群底部也赋存少量金矿床。主要金矿化类型为破碎带蚀变岩型,其次为石英脉型和硫化物石英脉型,有少量金矿化被划分为蚀变砾岩型、盆缘断裂角砾岩型、破碎带石英网脉带型、层间滑动构造带型和黄铁矿碳酸盐脉型,金属量在20 t以上的大型金矿大部分为破碎带蚀变岩型。中型以上金矿床的矿石量加权平均品位为4.07×10-6。胶东金矿床主要受区域性较大断裂及其次级断裂控制,控矿构造型式或位置主要有:断裂的拐弯部位、断裂倾角变化部位、断裂交会部位、入字型构造组合、帚状构造组合、菱形结环状构造组合和雁列构造组合,不同构造控制的金矿体的侧伏方向大致沿SW-NE同一直线方向展布。金矿床的蚀变、矿化、构造具有较好的分带性,破碎带蚀变岩型金矿的分带由弱至强表现为:网脉状—脉状钾化岩带、浸染状—网脉状黄铁绢英岩化碎裂岩化岩带和浸染状黄铁绢英岩质碎裂岩带(或黄铁绢英岩带)。前人虽然对胶东金矿进行了大量研究,但仍然存在一些尚待解决的关键问题,主要争议包括:(1)关于胶东金矿类型的认识主要有岩浆热液型、胶东型、克拉通破坏型和造山型等。(2)关于成矿地质体及成矿物质和流体来源的认识主要有:玲珑花岗岩或郭家岭花岗岩在金成矿中起到了重要作用或者是金矿的成矿地质体,成矿流体源于初始岩浆水;成矿物质来源具有多元性和复杂性,源自中生代活化再造的前寒武纪增生变质杂岩,成矿流体为壳—幔混合来源,以壳源变质流体为主;地幔来源的煌斑岩与金矿化有成因联系,成矿流体可能来源于基性幔源岩浆脱水;胶东金矿的形成与伟德山型花岗岩及同期的脉岩、火山岩有关。(3)关于胶东金矿成矿时代的主要认识有:金矿同位素年龄范围为123.0~110.6 Ma,大多数金矿床形成于(120±5)Ma;或是认为金矿床主要形成于134~126 Ma、122~119 Ma和110~107 Ma 3个时段;有125~115 Ma和100~90 Ma 2期成矿。
Jiaodong has become the third largest gold ore concentration area in the world because of the breakthrough of gold exploration in recently.This basic characteristics of the spatial distribution,structural orecontrolling,mineralization and alteration of Jiaodong gold deposits were summarized,and the main controversial issues about the gold deposits were analyzed.Jiaodong gold deposits are distributed among the three metallogenetic sub-regions namely the Jiaoxibei,Qipengfu and Muru,and there are five main ore-controlling fault zones.The ore hosting geological bodies in the area are mainly Jurassic Linglong-type granitoid,followed by the early Cambrian metamorphic rocks and the Cretaceous Guojialing-type granitoid,and a small number of gold deposits occurred in the Cretaceous Laiyang group.The major types of gold minralization are altered-rock type in the fracture zone and gold-bearing quartz vein type,and next are braided quartz vein type along the fracture zones,quartz-sulphide vein type,interlayer type along the detachment belt,altered-conglomerate type,breccia type along the basin margin faults and carbonate vein type.The large-sized gold deposits are mostly altered-rock type,and the average grade of the medium and large-sized gold deposits is 4.07×10-6.Jiaodong gold deposits are strictly controlled by regional larger fault and its secondary fault.The ore-controlling tectonic pattern or position mainly include:turn around of the fracture,change parts of fracture angle,intersection part of multifaults,intersect as small angle of faults,brush structures,the diamond ring structure combination,and echelon structure combination.The long-axis direction of oblique-arrange of gold orebodies that controlled by different fractures are distribution roughly the same straight line along the SW-NE direction.The gold deposits present the zoning characteristics of structure,alternation and mineralization,including cataclasitic zone of pyrite-sericitequartz alteration,cataclasitic granitoid zone of pyrite-sericite-quartz alteration and potassic granitoid zone.The hydrothermal alteration minerals related to gold mineralization mainly include quartz,sericite,pyrite,chalcopyrite,galena,sphalerite,silver gold and natural gold.Though significant research has been conducted about Jiaodong gold deposits,there are the following key issues remain to be solved.(1)There are magmatic hydrothermal type,Jiaodong type,Cratonic destruction type or orogenic type for the understandings of the Jiaodong gold mineralization.(2)The understandings about the ore-forming geological bodies,the source of oreforming material and fluid mainly include:Linglong type or Guojialing type granitoid played an important role in mineralization,and ore-forming fluid is the result of initial magmatic water;The ore-forming materials are diversity and complexity that derived from the Precambrian metamorphic basement rock mass which reactivated in the Mesozoic,and ore-forming fluids came from both the crust and mantle and are mainly the crust source metamorphic fluid;Mantle-derived lamprophyre associated with gold mineralization,and ore-forming fluid may be derived from the magma water that formed by the dehydration of the mantle-derived basic magma;The formation of Jiaodong gold deposits is related to the Weideshan type granitoid and its related dikes and volcanics.(3)The understandings about the metallogenic epoch of Jiaodong gold deposits are three main arguments:The isotopic age range is 123.0~110.6 Ma,and mostly are formed at(120±5)Ma;Jiaodong gold deposits formed in three period between 134 and 107 Ma;There are two metallogenic periods at 125~115 Ma and 100~90 Ma.
作者
宋明春
宋英昕
丁正江
李世勇
SONG Mingchun;SONG Yingxin;DING Zhengjiang;LI Shiyong(Bureau of Geology and Mineral Resources of Shandong Province,Jinan 250013,Shandong,China;Institute of Geological Sciences of Shandong Province,Jinan 250013,Shandong,China;8rd Survey Institute of Geology&Mineral Resources of Shandong,Yantai 264003,Shandong,China;Shandong Institute of Geophysical and Geochemical Exploration,Jinan 250013,Shandong,China)
出处
《黄金科学技术》
CSCD
2018年第4期406-422,共17页
Gold Science and Technology
基金
山东省重点研发计划项目"深部金矿成矿资源评价理论
方法与预测"(编号:2017CXGC1604)
山东省泰山学者建设工程专项经费"胶东型金矿的构造岩浆背景和深部找矿关键技术"(编号:ts201511076)联合资助
关键词
胶东金矿床
空间分布
构造控矿
金矿类型
成矿地质体
物质来源
成矿时代
Jiaodong gold deposits
spatial distribution
structural ore-controlling
type of gold mineralization
metallogenic geological body
material source
metallogenetic epoch
