青海红土沟金矿床地质特征与找矿标志探讨

红土沟金矿床位于中祁连地块与北祁连褶皱带的分界断裂中，出露地层主要有中寒武统和下奥陶统阴沟群。通过研究金矿体的赋存位置、状态以及观察镜下矿物特征，总结该区金矿床的地质特征和找矿标志，对下一步找矿具有重要的指示意义。该区金矿体均产于下奥陶统阴沟群中基性火山岩组第二段内，主要岩性有安山质玄武岩、绢云母石英片岩、黑云斜长变粒岩及部分变砂岩、大理岩等。矿体沿NW或近EW向断裂及其附近的蚀变破碎带分布，呈似层状、透镜状和脉状产出。金矿床矿石矿物主要为毒砂和黄铁矿，含微量自然金及自然银。脉石矿物主要有绢云母、白云石、白云母和石英。金品位变化较大，毒砂、黄铁矿是金的富集及载体矿物，金矿化与砷、硫金属矿物及硅化密切相关。金主要以次显微金形式存在（矿石中含量＞90%），其次以自然金形式存在。矿石构造类型以浸染状为主，脉状构造次之。

Discussion on the Geological Characteristics and Prospecting Signs of Hongtu- gou Gold Deposit in Qinghai Province

Hongtugou gold deposit is located in the boundary- fault between the Middle Qilian block and North Qilian fold belt, the exposed stratas are mainly Middle Cambrian and Lower Ordovician Yingou Group.By studing the location of gold orebody, occurrence of gold, ore mineral and gangue mineral, we sum up geological characteristics and prospecting signs of Hongtugou gold deposit,it will be very important for next exploring.The gold orebodies are all occurrence in the second part of the mafic volcanic rocks within Yingou Group,which mainly consist of andesitic basalt,quartz sericite schist,biotite plagioclase granulite and some metamorphous malmstone,marble and so on.Orebodies distribute at bedded,lenticular and vein along the north-west or nearly east-west trending faults and the ahered fracture zone near the fauhs.The ore minerals are mainly arsenopyrite, pyrite, a little native gold and native silver.Gangue minerals primarily include sericite, dolomite, muscovite and quartz.The change of gold grade is larger.Gold grains are mainly located and enriched in arsenopyrite and pyrite,which is closely related to the arsenic, sulfur metallic minerals and silicification.Gold grains are mainly in form of sub-microscopic grains （whose content is more than 90% in the ore）, followed by the existence in the form of native gold.Ore is mainly disseminated structure, vein structure followed.