甘肃中秦岭成矿带成矿规律及找矿远景

Ore-forming regularities of Middle Qinling metallogenic belt,Gansu Province and its prospective areas for ore-prospecting

文章在全面揭示甘肃中秦岭成矿带23种矿产成矿规律的基础上,圈定找矿远景区。通过成矿地质背景和成矿过程研究,建立主要矿床类型的成矿模式;以主要地质事件和成矿作用为主线,归纳矿床的时空分布规律和矿床成矿系列;通过矿床成矿系列与成矿模式相结合的方法预测找矿远景区。结果表明,浅成中-低温热液型铅锌矿由有地幔流体和岩浆流体参与的变质流体和建造水混合或沸腾形成;岩浆热液型金矿由源于下地壳的岩浆热液与大气水混合和沸腾形成,或由源于中地壳的岩浆热液与变质水混合后再与建造水或大气水混合形成;研究区存在7个矿床成矿系列。结论认为,中秦岭华力西期—印支期含矿流体矿床成矿系列分布区中,夏河-两当弧形断裂与近东西向断裂的交汇部位是该矿床成矿系列的成矿有利部位,中秦岭华力西期—印支期岩浆相关矿床成矿系列分布区中,中酸性岩体与近东西向断裂耦合部位是该成矿系列的成矿有利部位。文章圈定找矿远景区12处。

On the basis of overall metallogenic regularities of 23 kinds of mineral resources in the Middle Qinling metallogenic belt of Gansu Province,this paper aims to delineate ore-prospecting areas.Metallogenic models of main deposit types were built by studying of metallogenic & geological background as well as metallogenic process of mineral deposits.The spatial and temporal distribution regularities and metallogenic series of mineral deposits were summarized by taking main geological events and metallogenesis as key thread.With the combination of metallogenic series and metallogenic models of mineral deposits,the prospective areas of mineral deposits were predicted.The results are summarized as:the epithermal type lead-zinc deposits were formed from mixing or boiling of metamorphic fluid and sedimentary fluid,in which magmatic fluid and mantle fluid participated.The magmatic type gold deposits came from mixing and boiling of meteoric water and magmatic hydrothermal fluid derived from lower crust;or with two stages of mixing processes of fluids,i.e.,the fluid from mixing of magmatic hydrothermal fluid and metamorphic fluid again mixed in later stage with sedimentary water or meteoric water.There are 7 metallogenic series of mineral deposits.It is concluded as following:the favourable metallogenic conditions for Variscan-Indosinian ore-bearing fluid related metalogenic series in Middle Qinling mainly occur at the intersection of Xiahe-Liangdang arcuate-fault and approximately E-W striking faults,within the area of Variscan-Indosinian magmatism-related metallogenic series developed in Middle Qinling Belt,the high prospective areas are thought to be mainly at the coupling parts of intermediate-acidic intrusives and approximately E-W striking faults.12 high prospective areas were delineated.