豫西干树金矿钻孔原生晕地球化学特征及成矿预测

Geochemical Characteristics of Primary Halo in Boreholes and Metallogenic Prediction of Ganshu Gold Deposit in Western Henan Province

研究区位于华北板块南缘,熊耳山隆断区。区域结晶基底为太古宇太华群片麻岩,盖层为中元古界熊耳群火山岩、官道口群白云岩,区域断裂构造发育,燕山期岩浆活动频繁,成矿地质条件非常优越,是河南省著名的金、银、多金属生产基地。干树金矿位于熊耳山上宫金矿田内,上宫金矿田在全国"358"找矿突破战略行动中新增备案金资源量60 t以上,其重要成果之一是干树金矿深部找矿取得重大突破。干树金矿属热液作用形成的构造蚀变岩型金矿床,金矿体的产出严格受F1断裂控制。利用相关性分析、聚类分析对矿体元素亲疏程度进行了研究,采用格里戈良分带指数法确定了矿床原生晕的轴向分带序列,并通过原生晕等值线图对深部矿床进行了预测。研究表明:①Ag、Hg、Cu与Au关系最为密切,可以作为地球化学找矿的指示元素;②矿床原生晕的轴向分带序列为Hg→Ag→V→As→Au→W→Sb→Mn→Mo→Cu→Zn→Pb→Ba,反映矿床多期叠加成矿的特点,具有明显的"反分带"特征,预示着矿脉向深部还有很大的延深或者第二个隐伏矿体存在;③预测矿体向深部仍有很大的延深、且向北东侧侧伏;④在F1断裂深部0^-1 000 m标高、上宫41#线至干树66#线预测金资源量52.56 t。深部工程揭露了多层矿体或矿化带,Au、Ag、Cu、Pb、Zn单样最高品位分别达到2.60×10^-6、2 550×10^-6、1.16%、14.50%、15.52%,反映出上述成矿预测结果较为可靠,对于区域金矿床钻孔原生晕地球化学特征研究及成矿预测具有一定的借鉴意义。

The study area is located in the Xiongershan uplift fault area on the southern margin of the North Chinaplate. Crystalline basement of the regional is the gneiss of the Archean Taihua Group.Caprock of the regional is the volcanicrock of the Middle Proterozoic Xionger Group and the dolomite of the Guandaokou Group. The regional fault structure is de-veloped and the Yanshanian magmatic activity is frequent,so the ore-forming geological conditions are very superior. This isthe famous production base of gold,silver and polymetals in Henan Province. The Ganshu Gold Deposit is located in theShanggong Gold Orefield in Xiongershan. Shanggong Gold Orefield has added more than 60 tons of gold resources in the na-tional "358" prospecting breakthrough strategic action,and one of its important achievements is that Ganshu Gold Mine hasmade a major breakthrough in deep prospecting. Ganshu Gold Deposit belongs to tectonic altered rock type gold deposit formed by hydrothermal process,and the occurrence of gold orebody is strictly controlled by F1 fault. The affinity degree oforebody elements is studied by correlation analysis and cluster analysis,and the axial zoning sequence of the primary halo ofthe deposit is determined by the Gregorian zoning index method,and the deep ore deposits are predicted by the primary haloisoline map. The study achievements have been obtained as follows:(1) Ag,Hg and Cu are most closely related to Au,so theycan be used as indicator elements for geochemical prospecting.(2) The axial zoning sequence of the primary halo is Hg→Ag→V→As→Au→W→Sb→Mn→Mo→Cu→Zn→Pb→Ba. It reflects the characteristics of multi-stage superimposed mineralizationof the deposit,and the obvious characteristics of "reverse zoning" indicate that there is a great extension to the depth of thevein or the existence of a second concealed orebody.(3)It is predicted that the orebody still extends to the deep and lies side-ways to the north-east. Deep engineering reveals multi-layer orebodies or mineralized zones.(4)It is predicted that the amount ofgold resources is 52.56 t in the deep 0^-1 000 m elevation of F1 and the line from Shanggong 4#exploration line to Ganshu 6#exploration line.The highest grade of Au,Ag,Cu,Pb and Zn reached 2.60 ×10^-6,2 550 ×10^-6,1.16%,14.50% and 15.52%respectively. It shows that the metallogenic prediction results of this study are reliable and can be used as a reference for thestudy of geochemical characteristics of borehole primary halo and metallogenic prediction of regional gold deposits.