山西省狐姑山BIF铁矿三维空间分布规律及深部预测

Three-Dimensional Spatial Distribution Law and Deep Prospecting of the Hugushan BIF Iron Deposit,Shanxi Province

狐姑山铁矿是吕梁地区一个大型BIF铁矿床,该矿床成矿经历多期次构造-变形-岩浆活动,矿体形态极其复杂且空间分布不清,阻碍了深边部找矿效果。在系统的野外地质调查、矿石显微组构分析的基础上,进一步采用三维建模软件构建了狐姑山地层、矿体、断裂、岩浆岩等控矿要素的三维空间模型,结果显示:(1)铁矿主要受袁家村组地层与区域变质作用控制;(2)矿体形成后主要经历了EW向与近SN向的挤压构造应力作用,产生了褶皱变形,形成了连续平行分布的凹凸体,其垂向变形最大幅度达220 m;(3)成矿后的断裂错断矿体且断距较小,基性岩脉对矿体具有明显的破坏作用;(4)深部矿体倾角逐渐变缓,典型勘探线剖面高精度磁测与大地电磁测深结果显示深部异常体连续且有稳定延伸。综合矿床地质特征、三维空间分布、磁化率及电阻率异常特征认为,狐姑山矿床深边部均具有较大的找矿前景,并圈定了3个找矿靶区。

The Hugushan deposit is a large BIF iron deposit in the Lüliang area,which has experienced multi-stage tectonic-deformation-magmatic activities after mineralization.The orebody shape is extremely complex and the spatial distribution is unclear,hindering the prospecting effect in the deep and edge.On the basis of systematic field geological survey and ore microstructure analysis,the three-dimensional spatial model of ore-controlling factors such as formation,orebody,fault and magmatic rock in Hugushan deposit was further constructed by 3D modeling software.The results show that:(1)Iron ores are mainly controlled by Yuanjiacun Formation and regional metamorphism;(2)After the formation of the orebody,the extrusion tectonic stress in EW direction and nearly SN direction resulted in folds,and formed a continuous parallel distribution of concave and convex bodies with the maximum vertical deformation of 220 m;(3)The faults after mineralization cut through the orebody with small fault distance,whereas the basic dikes had obvious destructive effect on the orebody;(4)The dip angle of deep orebody gradually became gentle.The results of high precision magnetic survey and magnetotelluric sounding of typical exploration line section show that the deep anomaly orebody is continuous and shows stable extension.Based on the geological characteristics,three-dimensional spatial distribution,magnetic susceptibility and resistivity anomalies,it is suggested that the deep of Hugushan deposit has great prospecting potential,and three prospecting targets are determined.