胶东望儿山金矿床氢-氧同位素地球化学  

Hydrogen and oxygen isotopes geochemistry of the Wang'ershan gold deposit Jiaodong

作　　者：郭林楠[1] 张潮[1] 宋宇宙[2] 陈炳翰 周铸[1,3] 张炳林[1] 徐晓磊[2] 王彦玮[2] 

机构地区：[1]中国地质大学地质过程与矿产资源国家重点实验室,北京100083 [2]山东黄金集团有限公司焦家金矿,莱州261441 [3]中国矿业报社,北京100055

出　　处：《岩石学报》2014年第9期2481-2494,共14页Acta Petrologica Sinica

基　　金：国家自然科学基金重点项目(41230311);国家科技支撑计划课题(2011BAB04B09);地质过程与矿产资源国家重点实验室开放课题(GPMR201307)联合资助

摘　　要：胶东金成矿省位于华北克拉通东南缘,是我国最重要的黄金集区,约占全国黄金储量的25%。其中约90%的金资源量集中于胶东半岛的西北部,主要受3个一级断裂带(三山岛断裂带、焦家断裂带和招平断裂带)控制。望儿山金矿床赋存于晚侏罗世玲珑型黑云母花岗岩中,受焦家断裂带的次级断裂带(望儿山断裂带)控制,是胶东地区受二级断裂带控制的已探明规模最大的金矿床,同时发育蚀变岩型矿化和石英脉型矿化。金矿化与硅化和绢云母化蚀变密切相关,矿体多呈脉状,主要为矿区内主干断裂F1和F5控制的1号和5号矿体以及F1和F5的次级断裂控制的3号和23号矿体。矿石分为蚀变岩型和石英脉型,主要由石英、绢云母及黄铁矿、黄铜矿、方铅矿、闪锌矿等金属硫化物等组成。本研究通过详细的野外和岩相学、矿相学观察,依据蚀变特征、脉体穿插关系及矿石结构构造和矿物共生组合,将成矿过程分为四个阶段:黄铁矿-石英-绢云母阶段(Ⅰ)、石英-黄铁矿阶段(Ⅱ)、石英-多金属硫化物阶段(Ⅲ)和石英-碳酸盐阶段(Ⅳ)。针对不同高程、不同成矿阶段、不同矿石类型、不同矿体,系统采集了26件样品,分别挑选石英单矿物进行氢、氧同位素测试,总体δD值分布于-77.3‰^-54.2‰,δ18O值分布于-5.56‰~7.20‰,Ⅰ阶段δD=(-62.2±6.6)‰(n=8),δ18O=(4.60±1.52)‰(n=8);Ⅱ阶段δD=(-62.5±4.5)‰(n=7),δ18O=(0.47±2.86)‰(n=7);Ⅲ阶段δD=(-66.5±3.9)‰(n=8),δ18O=(-0.44±2.21)‰(n=8);Ⅳ阶段δD=(-65.6±4.5)‰(n=3),δ18O=(-4.43±1.09)‰(n=3)。根据氢-氧同位素组成及流体混合作用图解和水-岩交换氢氧同位素演化曲线,得出变质水与大气降水的混合流体与成矿相关。成矿流体来源主要为胶东群变质水,随着成矿作用的进行,更多大气降水混入成矿流体,成矿Ⅲ、Ⅳ阶段流体很可能以大气降水为主。成矿流体依据其流动方式主要分为�The Jiaodong gold metallogenic province is located in the southeast of the North China craton, and it defines China＇ s largest gold province, which account for about 25% of the national gold reserves. Roughly 90% of the gold is concentrated in the northwestern Jiaodong Peninsula, and mainly controled by three first-level fault belts （ Sanshandao fault belt, Jiaojia fault belt and Zhaoping fault belt）. The Wang＇ ershan .gold deposit, occuring in the Late Jurassic Linglong-type biotite granite, is controled by secondary fault zone in Jiaojia fault belt, the Wang＇ ershan fault zone. As Jiaodong＇ s largest proven gold deposit which is controlled by second-level fault belt, it develops both altered rock type and quartz vein type mineralization. The four main lode gold orebodies generally locate in the silicification and sericitization zones, No. 1 and No. 5 orebodies are controled by two main faults, F1 and F5 , in the mine respectively, No. 3 and No. 23 orebodies are controled by secondary fractures of F1 and F5. The altered rock type and quartz vein type ores consist of quartz, sericite, pyrite, chalcopyrite, galena, sphalerite, etc. Four mineralization stages have been identified on the basis of alteration characteristics and crosscutting relationships observed in the field, and structure, texture and mineral assemblages by petrography and ore microscopy observation. They include a pyrite-quartz-sericite stage （ I ）, a quartz-pyrite stage （ Ⅱ ）, a quartz-polysulfide stage （ Ⅲ ） and a quartz-carbonate stage （ Ⅳ ）. Twenty-six samples were collected according to elevations, mineralization stages, ore types and ore bodies. Pure quartz grains were selected from the samples for hydrogen and oxygen isotopic analyses. It shows 8D values of -77. 3‰ -54. 2‰, and δ18O varying from -5. 56‰ to 7. 20‰. From stage I to IV, hydrogen and oxygen isotopic compositions are 8D = （ - 62. 2 ~ 6. 6） ‰ （ n = 8 ）, δTM O = （4. 60 ~ 1.52） ‰ （ n = 8 ） ; 8D = （ - 62. 5 ~ 4. 5 ）

关 键 词：氢-氧同位素 成矿流体演化 流体流动方式 金成矿机制 望儿山金矿床 胶东 

分 类 号：P595[天文地球—地球化学] P618.51[天文地球—地质学]