内蒙古锡林郭勒盟布金黑铅锌矿床Ⅱ号矿脉地质特征及成矿预测

Geological features and metallogenic prediction of ore vein Ⅱ in Bujinhei Pb-Zn deposit,Xilingele League,Inner Mongolia

布金黑铅锌矿床为典型的中温热液脉型矿床,矿体呈脉状、透镜状产出于寿山沟组下段的变质砂板岩之中,其中Ⅱ号矿脉是该矿床主要的工业矿体,总体呈近EW向展布。通过矿区地质、矿化特征、磁法测量及OPIS计算机模拟,指出在断裂构造EW与NE方向转变的地带易成矿,且矿化体具有高极化率、高磁化率、高厚度和高品位特征。磁异常图表现为呈近东西向线性分布的磁异常水平一阶90°、135°导数等值线与近EW向断裂相对应,异常梯度大的区域对应断裂构造方向改变地带。OPIS预测图表明矿体的位置对应数据的高值的中心部位、中心部位附近,或位于断裂面距离变化较陡部位。据此,圈定了Ⅰ、Ⅱ、Ⅲ、Ⅳ四处外围找矿靶区及Ⅱ-1、Ⅱ-2、Ⅱ-3三处深部找矿靶区,其中Ⅱ-2靶区已被验证。

The Bujinhei Pb-Zn deposit with a lenticular and vein ore bodies,is a representative medium temperature hydrothermal vein-type deposit,occurred in the metamorphic sandstone and slate of the lower member of Shoushangou Formation. The EW-oriented ore vein Ⅱ is well productive for industry. According to the analysis of orefield geology,ore characteristics,magnetic survey and OPIS simulation,the transitional tectonic fractures between EW and NE direction are reported as the zone where ore is easily to deposit. In addition,the mineralized bodies are featured by high polarizability,high susceptibility,high thickness and high grade. Magnetic abnormal maps manifest that the nearly EW extended contours of the first order level of 90° and 135° derivative of magnetic anomaly correspond to nearly EW-oriented fracture,and great abnomal gradient zone corresponds to the transitional area of fracture direction. Sketch map of OPIS prediction manifests that orebody positions correspond to high value central part and around the centre zone or greater steep part of fracture surface distance. As a result,the four peripheral targets Ⅰ,Ⅱ,Ⅲ and Ⅳ,and three deep targets Ⅱ-1,Ⅱ-2 and Ⅱ-3,have been delineated,and thetarget Ⅱ-2 has been verified.