胶东西岭金矿床地质特征与金的赋存状态

Geological Characteristics and Occurrence of Gold in the Xiling Gold Deposit,Jiaodong Peninsula

西岭金矿床是胶东金矿集区内近来新发现的超大型破碎蚀变岩型金矿床(475吨@4.56 g/t),位于著名的三山岛金矿床的东侧。本文在详实的野外地质观察的基础上,系统介绍了西岭金矿床的基础地质特征,并运用光学显微镜和扫描电镜观察,结合电子探针分析,系统研究了西岭金矿床金的赋存状态。西岭金矿床大量金矿物(银金矿和自然金)主要赋存在Ⅱ阶段石英-黄铁矿和Ⅲ阶段灰石英-多金属硫化物脉中。西岭金矿床金矿物主要有晶隙金、裂隙金和包体金三种赋存状态,以晶隙金为主。金的主要载体矿物为黄铁矿,次为石英、黄铜矿和方铅矿等。金矿物粒度大小包括粗粒金、中粒金、细粒金和微粒金,以细粒-微粒为主。金矿物形态有粒状、叶片状、线状、钩状、枝杈状和哑铃状等,以粒状为主。金矿物成分以Au和Ag为主,含微量的Cu、Cr、Fe、Ni、Te、S等元素。金成色为685~831,以银金矿为主,含少量自然金。综合地质和地球化学特征,西岭金矿床为蚀变岩型金矿床,是由早白垩世中温岩浆热液充填-交代形成。

The Xiling gold deposit, located on the east side of the well-known Sanshandao gold deposit, is a newly discovered super-large one of the fractured altered rock type(475 tonnages @4.56 g/t) in the Jiaodong gold-concentration district.Based on the detailed field geological observations, this paper presents the basic geological characteristics of the Xiling gold deposit.Besides, we systematically studied the occurrence of gold in the deposit by using optical microscope and scanning electron microscope observations combined with electron microprobe analysis.Abundant gold grains(electrum and native gold) in the Xiling gold deposit are mainly hosted in the quartz-pyrite(Stage Ⅱ) and gray quartz-polymetallic sulfide veins(Stage Ⅲ).There are three main occurrences of gold in the Xiling gold deposit, including interstitial gold(primary),fissure gold, and inclusion gold.Gold grains are mainly found in pyrite, followed by chalcopyrite, galena and quartz.Gold grains of various particle sizes(coarse-grained, medium-grained, fine-grained, and micro-grained) are present in the Xiling gold deposit, dominated by micro-fine gold grain.The gold grains are primarily granular-based in the Xiling gold deposit, and others like leaf-like, linear-like, hook-like, branch-like, dumbbell-like, etc.are also obsreved.The compositions of gold are dominated by Au and Ag, containing trace amounts of Cu, Cr, Fe, Ni, Te and S.The gold fineness ranges from 685 to 831,and gold grains are dominated by electrum, with a small amount of native gold.Combined with geological and geochemical characteristics, the Xiling gold deposit is of the altered rock type, formed by mesothermal magmatic-hydrothermal filling-metasomatic during the Early Cretaceous.