坦桑尼亚太古代克拉通斑岩型金矿床地质特征及找矿方向

Geological characteristics and prospecting direction of Archean craton porphyry-type gold deposits in Tanzania

坦桑尼亚太古代克拉通花岗-绿岩带是著名的金矿聚集区之一,斑岩型金矿床是其重要组成部分,找矿潜力较大。通过对该区域典型斑岩型金矿床地质特征、矿床地球化学特征、控矿因素、成矿流体、成矿物质来源及矿床成因进行研究,认为含矿斑岩属钙碱性系列,形成于岛弧环境,以岩浆热液成矿作用为主;矿体分布在斑岩体内及与绿岩带接触带部位,主要产于钾化-硅化蚀变带和硅化-绢云母化-硫化物带内;同位素特征显示,成矿物质来源于深部岩浆,成矿流体为岩浆水;总结了坦桑尼亚太古代克拉通斑岩型金矿床成矿模式,认为太古代克拉通斑岩体与绿岩带之间的深大断裂和斑岩体边部接触带是未来重点找矿靶区。

The granite-greenstone belt in the Archean craton of Tanzania is one of the well-known gold accumulation zones,and porphyry-type gold deposits are a significant part of it,showing substantial exploration potential.This study investigates the geological characteristics,geochemical features,ore-controlling factors,metallogenic fluids,sources of metallogenic materials,and genesis of typical porphyry-type gold deposits in the region.It is concluded that the mineral-bearing porphyry belongs to the calc-alkaline series,formed in an island arc environment,primarily by magmatic-hydrothermal processes.The ore bodies are distributed within the porphyry and at the contact zones with the greenstone belt,mainly in potassium-silica alteration zones and silica-sericite-sulfide belts.Isotopic characteristics indicate that the metallogenic materials originated from deep magma,and the metallogenic fluid is magmatic water.A metallogenic model for the Archean craton s porphyry-type gold deposits is summarized,suggesting that deep faults between the Archean craton s porphyry bodies and the greenstone belt,as well as the marginal contact zones of the porphyry bodies,should be the main targets for future exploration.