白云金矿床60号脉带原生晕分带特征及深部含矿性评价

Characteristics of primary halo and evaluation of deep mineralization along No.60 vein zone of Baiyun gold deposit

白云金矿床产于华北地台东端辽东-吉南裂谷带内,是古元古代变质岩地层中的代表性矿床,60号脉带是现有埋藏最深、规模最大的矿脉群,矿体赋存在黑云母片岩、黑云母变粒岩与大理岩接触界面附近,主要受近东西向层间滑脱构造控制,最大延长1240 m,倾斜延深600 m,平均品位3.82×10^(-6)。为了评价60号脉的深部找矿潜力,进而指导深部找矿方向,本次工作采集了60号脉带坑道和钻孔原生晕样品,研究其地球化学分带特征,进一步评价其深部含矿性及找矿方向。原生晕分带特征研究表明,白云金矿的前缘晕主要元素为Hg、Sb、As;近矿晕元素为Au、Cu、Pb、Zn;尾晕元素为Co、Mn、Mo。运用重心法确定白云金矿垂向分带为(由上到下):Cr-Mn-Ni-F-BSn-As—W-Au-Mo-Hg-Cu-Sb-Pb—Ag-Co-Zn-Bi,结合元素分带特征,构建了白云金矿床60号脉带原生晕模式,并建立了前缘晕与尾晕累加比值的地球化学参数。在矿区浅部,出现前、尾晕叠加,对应现已控制的矿体;在深部,再一次出现前、尾晕叠加,且前缘晕元素异常较强的现象,预示着深部存在盲矿体。通过原生晕分带特征研究,预测了4个深部找矿靶区,分别在056勘探线与064勘探线之间的-400 m标高、-800 m标高、-1000 m标高、-1200 m标高范围内。

The Baiyun gold deposit occurs in the Liaodong-Jinnan rift zone at the eastern end of the North China platform,being a representative deposit in the Paleoproterozoic metamorphic strata in eastern Liaoning area.The No.60 vein zone is the buried largest orebody in this area.It occurs near the contact interface between biotite schist,biotite granulite and marble,and is mainly controlled by the nearly EW-trending interlayer sliding structure.The maximum extension is 1240 m,the dip extension is 600 m,and the average grade is 3.82×10^(-6).In order to evaluate the deep ore-prospecting potential of No.60 vein and guide deep ore-prospecting,the authors collected primary halo samples along the tunnel and drill hole of No.60 vein to study its geochemical zoning characteristics and further evaluate its deep ore-bearing property and ore-prospecting direction.The study of the characteristics of the primary halos shows that the main elements of the leading halos in the Baiyun gold deposit are Hg,Sb and As,the near-halo elements are Au,Cu,Pb and Zn,and the rear halo elements are Co,Mn and Mo.The center of the gravity method was used to determine the vertical zoning of The Baiyun gold deposit,which is in downward order of CR-Mn-Ni-F-B-SN-AS-W-Au-Mo-Cu-SB-PB-AG-Co-Zn-BI,the primary halo model of the 60 pulse zone of the Baiyun gold deposit was constructed in combination with the zonal characteristics of elements,and the geochemical parameters of the accumulated ratio of the leading and trailing halos were established.In the shallow part of the mining area,the front and tail halos are superimposed upon each other,corresponding to the orebodies that are now under control.In the depth,the superposition of the fore and rear halos and the strong anomaly of elements in the leading halos appear again,indicating the existence of blind orebo-dies in the depth.Through the study of the characteristics of the primary halo zoning,four deep prospecting target areas were delineated,which are within the range of-400 m elevation,-800 m elevation,-1000 m elevation and-1200 m elevation respectively between No.056 and No.064 exploration lines.