河北青龙河地区下元古界浊积岩金矿床

笔者应用岩石学、构造学、矿床学、地球化学等手段和方法研究了该区金矿床的特点和形成条件,结果表明青龙河金矿的容矿岩石是一套成分以火山(碎屑)岩岩屑为主的浊积岩,其含金量高达2.87g/t,且金主要与硫化物共生,浊积岩是金的矿源层。矿区内有细脉浸染型和含金石英脉型矿床。金矿的形成受浊流作用、火山作用和后生热液作用的控制。

GOLD DEPOSITS OF LOWER PROTEROZOIC TURBIDITES IN THE QINGLONG RIVER AREA,HEBEI

The Qinglong River goldore district is located in the southeastern part of Qing-long county, Hebei province. There are mainly six gold occurrences (Miaozhengzi,Ciyugou, Huangzhangzi, Banbishang, Zhangzhangzi and Jinshangou) in the area.Gold orebodies occur in low--grade metamorphic rocks of the Zhangjiagou Forma-tion of the Lower Proterozoic Zhuzhangzi Group. Their protoliths are volcano--tur-bidites and graywacke. The entire ore district is an overturned synclinorium. Theoccurrence of the orebodies is strictly controlled by the strata, folds and theQinglong River fault. Orebodies are mainly stratified and veinlike. The ore miner-als are mainly pyrite, native gold and arsenopyrite with minor chalcopyriteand pyrrhotite. Gangue minerals are minly quartz, plagioclase and carbonateminerals. Host rocks are rich in SiO_2, Al_2O_3, FeO and CaO.The enrichment of goldis closely related to trace elements such as Pb, As and Sb. Gold mineralization isintimately associated with pyrite and arsenopyrite. The host rocks in the Qinglong River gold district were formed by the actionof turbidity currents on volcanic materials in the magmatic arc.Gold was broughtup from depths by volcanic eruption.The hydrothermal fluids from volcanic exha-lation and turbidities were deposited simultaneously to form stratified veins. Thereconstitution of gold--bearing rocks by late--stage metamorphic hydrothermal flu-ids and magmatic fluids resulted in the formation of stockwork--disseminated golddeposits and gold--bearing quartz vein gold deposits in the favorable structuralplaces. The formation of the gold deposits is related to both the syngenesis of volcan- ic-turbidity currents and the reconstitution by epigenetic hydrothermal fluids.