大店沟金矿矿床特征与成因分析

陕西省核工业地质调查院,陕西 西安 710054

西秦岭; 大店沟金矿; 特征与成因分析

Characteristics and causes of Dadiangou Gold Deposit
ZHANG Jing-ping,HU Xi-you

(Shaanxi Province Nuclear Industry Geological Survey,Xi'an 710054,China)

west Qinling mountains; Dadiangou gold deposit; characteristics and cause analysis

备注

甘肃省两当县大店沟金矿床位于北秦岭西段,矿体呈似层状、脉状、透镜状等产出; 主要赋存于丹凤群木其滩组第三岩性段绢云绿泥石英片岩中; 望天沟-利桥复背斜及舒家坝-太阳寺大断裂控制了金矿的定位,元家坪-小寺沟韧性剪切带及次级韧性剪切挤压带控制了金矿化体的空间展布及形态。矿石类型可分为黄铁矿化石英脉型和黄铁矿蚀变岩型2类。矿石结构主要为鳞片变晶结构,构造主要为千枚状构造、条带状构造。金以微粒金产出,主要载金矿物为黄铁矿。通过综合研究表明,加里东运动使地层受到高绿片岩相的温、压作用,造成了金元素的活化及初步富集; 印支期活动的热液使金进一步富集,同时为石英脉体串通韧性剪切带的薄弱地带提供了动力,又为后来的金矿化准备了储矿空间。研究表明,该矿床受韧性剪切带及含金地层控制,具多期次金富集成矿成因特点。

Dadiangou Gold Deposit is located in the western part of northern Qinling Mountains,Liangdang County of Gansu province,the ore bodies are bedded,vein,lenticular,output; occurs mainly in Danfeng Group Muqitan third lithologic unit Juanyun chlorite schist; Wangtiangou-Liqiao anticlinorium and Shujiaba-Taiyangsi faults control the gold positioning,Yuanjiaping-Xiaosigou ductile shear zone and the secondary ductile shear zone control the spatial distribution and morphology of gold ore body.The ore types can be divided into pyrite quartz vein and pyrite alteration rock.The main ore structure is lepidoblastic texture mainly phyllitic structure and structure.Gold is from particle gold output,the main gold carrying mineral is pyrite.Through comprehensive study,Caledonian movement made the formation pressure by high greenschist facies,temperature,caused the activation of gold element and preliminary enrichment; hydrothermal Indosinian activity made the gold enrichment further,at the same timeprovides dynamic force for weak zoneof the quartz veins ductile shear zone,but also prepares the storage space for the later gold mineral.Research shows that,the deposit is controlled by the ductile shear zone and gold bearing strata,with features ofmany times of gold mineralization.