滇东北乐红铅锌矿原生晕特征及深部找矿预测

鲁甸县乐红铅锌矿床位于滇东北矿集区,是新近发现的大型铅锌多金属沉积—热液改造型矿床。结合矿区地质背景、矿床成因、矿体特征及坑道岩石地球化学采样分析,系统详细地研究了乐红铅锌矿床深部的原生晕地球化学特征,结果表明:(1)矿体前缘元素和近矿元素为Ag、As、Sb、W、Hg、Zn、Mo,中程指示元素为Co、Ni,尾晕元素为Ba、Cu;(2)根据Grigorian原生晕分带原理,得出其轴向分带序列(由上至下各中段)为Ag-Zn-Mo-As-Hg-W-Co-Ni-Sb-Pb-Cu-Ba-Au-Sn,表明成矿过程存在多期矿化叠加;(3)采用多元统计的方法研究了各成矿元素及伴生元素的亲和性,并构建原生晕叠加模式、Ag/Cu、F1因子等深部找矿预测模型评价指标。综合原生晕各项特征,认为在1350中段以下应有隐伏矿体发育。此外,乐红矿床赋存状态为沿F2断裂近直立分布,垂向坑道岩石地球化学采样分析预测,深部具有成矿潜力,存在良好的找矿前景。

Geochemical characteristics of primary halo and prospecting of LehongPb-Zn deposit in northeastern Yunnan

The Lehong deposit located in mineralization concentration area of northeastern Yunnan, is a newly discovdred large-sized Pb-Zn polymetallic deposit which belongs to sedimentary-hydrothermal reformed type deposit.Combined with geological background, deposit genesis, orebody characteristics, geochemical analysis of tunnel rock samples, the geochemical characteristics of primary halos in the depth of the Lehong lead-zinc deposit is analyzed. The results indicate that Ag, As, Sb, W, Hg, Zn, Mo elements belong to the frontal halo elements and indicator elements near the ore bodies, Co, Ni elements belong to medium-range indicator elements, and Ba and Cu elements belong to rear halo elements.Axial zoning sequence of primary halo can be classified as followings from upper to lower part:Ag-Zn-Mo-As-Hg-W-Co-Ni-Sb-Pb-Cu-Ba-Au-Sn. It shows multiple stages of ore-forming evolution.Besides, the affinity of the ore-forming elements and associated elements are studied by using the multivariate statistical method,and primary halos superposition model is constructed. And Ag/Cu ratio and F1 factor are selected to predict deep prospecting model evaluation index.The comprehensive primary halos characteristics indicate that concealed orebody may occur below 1350m level. In addition, the Lehong lead-zinc orebody is distributed as vertical form along F2 fault, and the geochemical sampling results of vertical tunnel sampling also indicate that there is great possibility of finding new orebodies in the depth.