青海鄂拉山口银铅锌矿床成矿地质特征及找矿标志

The Geological Features of Prospecting Indicator in Elashankou Silver-Lead-Zinc Deposit,Qinghai Province

鄂拉山口银铅锌矿床的发现是近几年来在青海省鄂拉山成矿带上找矿的重大突破。该矿床主要产于晚三叠世(鄂拉山组)陆相火山岩地层中。以鄂拉山口银铅锌矿区多年勘查成果为依据,从地层、构造、火成岩、围岩蚀变、控矿因素及成矿规律等方面,对鄂拉山银铅锌矿床成矿地质条件进行分析,结果显示该区具备良好的找矿前景。矿床成因受火山喷发—喷溢及酸性熔岩的影响,矿体产于复杂的(流纹质、安山质和英安质)火山角砾凝灰熔岩组合中,形成以硫铁矿化为主的铜银铅锌矿化体,并在此基础上叠加了后期NW向断裂及中酸性岩浆的侵入,最终形成了受火山机构和NW向断裂控制的矿床格局,综合分析,该矿床属于陆相火山—次火山岩(热液型)矿床。

The discovery of Elashankou silver-lead-zinc deposit is a major breakthrough in the prospecting of Elashan metallogenic belt in Qinghai Province.This deposit is mainly produced in terrestrial volcanic rocks of the Late Triassic（Elashan group）.We discuss the geological conditions of the silver -lead-zinc deposit based on years of exploration results about the formation,structure,igneous rock,wall rock alteration,ore-controlling factors and metallogenic regularity,etc.We suggest that the deposit is impacted by the volcanic eruptions and acidic lava,and the ore produces in the eomplex（rhyolitic,andesitic,dacitic） volcanic breccia tuff lava combination,formed coppersilver-lead-zinc body in which pyrite is predominant,based on this,with the superimposed of the acidic magma intrusion in late NW-trending fauhs,eventually formed deposits pattern,which is controlled by the volcanic bodies and NW-trending faults.Comprehensive analysis show that the deposit belongs to terrestrial volcano-subvolcanic type （hydrothermal） deposits.