构造原生晕在攻深找盲中的应用——以赣南银坑牛形坝铅锌金银矿床为例

Application of tectonic primary halos in the exploration of deep concealed ore bodies:A case study of the Niuxingba plumbum-zinc-gold-silver deposit in Yinkeng,southern Jiangxi

牛形坝铅锌金银矿床为南岭EW向成矿带与武夷山NNE向成矿带交汇处银坑矿田内新发现的一个严格受断裂构造控制的典型热液脉型矿床,矿体呈脉群状产出。为了预测该矿床V31号主矿带(体)的深部找矿潜力,在对矿床地质特征分析的基础上,系统开展了矿床V31号主矿带(体)轴(垂)向、横向和纵向构造原生晕地球化学特征及分带研究,建立了构造原生晕轴向分带序列和矿床构造原生晕地质—地球化学模型,并运用多元统计方法验证了模型的正确性、合理性、可靠性。构造原生晕地质—地球化学模型表明:牛形坝铅锌金银矿床前缘晕指示元素为F;近矿晕指示元素一类为与金矿化有关的As-Au元素组合,位于矿体中上部,一类为与铅锌银矿化有关的Hg-Zn-Pb-Ag-Cu-Bi-Sb元素组合,位于矿体中部;尾晕指示元素为Mo-Cr-Co-Ni。前缘—近矿—尾晕三者异常中心轴向相距约200~300 m,具明显的“头尾晕共存”和“近矿晕折线拐点”特征,且往东出现中低温Pb、Zn、Ag、Au矿化向中高温Cu、Zn矿化转变,指示V31号主矿带(体)走向东侧伏,倾向往深部仍有较大延伸(至少可延伸至-200 m标高)或有盲矿体存在,经东部隐伏区深部钻探工程验证(367线最低见矿标高-165 m),表明V31号矿带(体)东部、深处有较大的增储潜力。

The Niuxingba plumbum-zinc-gold-silver deposit(the Niuxingba deposit)occurs in the Yinkeng ore field at the intersection of the EW-trending Nanling metallogenic belt and the NNE-striking Wuyishan metallogenic belt.It is a typical hydrothermal vein depos-it under the strict control of fault structures,with ore bodies occurring as vein groups.To predict the deep prospecting potential of the No.V31 major ore belt(body)of the Niuxingba deposit,this study systematically investigated the axial(vertical),transverse,and longitudinal geochemical characteristics and zoning of tectonic primary halos of the ore belt(body)based on the geological characteris-tics of the deposit.Then,this study determined the axial zoning sequence and the geological-geochemical model of tectonic primary ha-los.It was confirmed that this model was correct,reasonable,and reliable using the multivariate statistical method.The results of the geological-geochemical model show that:①the front halo of the Niuxingba deposit has F as the indicator element;②the near-ore halo has two types of indicator elements:the gold mineralization-related As-Au element association in the middle and upper parts of the ore body and the Pb-Zn-Ag mineralization-related Hg-Zn-Pb-Ag-Cu-Bi-Sb element association in the middle part of the ore body;③the rear halo has the Mo-Cr-Co-Ni element association as indicator elements;④the anomaly centers of the front,near-ore,and rear halos are about 200~300 m apart axially,suggesting significant coexistence of front and rear halos and the presence of inflection points of the near-ore halo broken line.Furthermore,the transformation of low-moderate-temperature Pb-Zn-Ag-Au mineralization into moderate-high-temperature Cu-Zn mineralization occurs eastward.These characteristics indicate that the No.V31 main ore belt(body)has a pitch direction of east and a large extension toward the deep part(to an elevation of-200 m at least),implying that blind ore bodies may occur.As verified by deep drilling in the eastern concealed area(the lowest ore-controlled elevation of the No.367 survey line:-165 m),the eastern deep part of the No.V31 ore belt(body)has a high potential for increasing reserves.