招平断裂带大尹格庄—后仓段深部矿体定位预测

大尹格庄—后仓测区位于招平断裂带中段之大尹格庄金矿东侧。根据深部探矿目标区的特点和方法的有效性试验,选择构造地球化学测量和大地电磁测深作为深部矿体定位预测的手段。本次地表构造地球化学测量范围约8 km2,在测区中部、东部和西部发现3处成规模的Au元素异常带,结合因子分析,提出Au-As-Hg-Cu-Pb-Zn元素组合异常对应深部成矿流体活跃地段,Au和As元素可作为深部矿体预测的主要标志元素,Cu、Pb、Zn等元素异常更多地反映了多金属硫化物成矿阶段流体活跃的地段,可作为辅助标志。岩、矿石样品电阻率测定显示,与招平断裂带有直接空间关系的富矿石、黄铁绢英岩化蚀变岩及断层泥表现为显著的低阻体,与上、下盘的胶东群变质岩和玲珑花岗岩电阻率值差异明显,为大地电磁测深的有效性提供了依据。根据大地电磁法获得的深部呈串珠状分布的低阻异常,圈定出玲珑花岗岩与胶东群变质岩界线、招平断裂带位置,深部低阻异常中心指示了断裂带局部膨大和成矿有利部位。根据构造地球化学元素组合异常和大地电磁测深电阻率异常的空间分布关系,共圈定找矿靶位8处,钻探工程验证在1 150～1 450 m深度发现了金矿体。

Oriental prognosis of deep orebodies in Dayingezhuang—Houcang mining area of Zhaoping fault zone

Dayingezhuang—Houcang surveying area is located in the east part of Dayingezhuang gold deposit,which situates in the middle part of Zhaoping fault zone.Tectonic geochemistry and magnetotelluric sounding(MT) were chosen as the means for oriental prognosis of deep orebodies according to the characteristic of target area in depth and the efficiency of technique test.The area of tectonic geochemical measurement is about 8 km2.Three scaled anomalies of Au were found in the middle,east and west parts of the surveying area.Integrated with factor analysis,the combined anomalies of Au-As-Hg-Cu-Pb-Zn could be considered as the active sites of ore-forming fluid.Au and As were the main marked elements of ore prediction.The anomalies of Cu,Pb and Zn were subsidiary signs.The resistivity measurement of rock and ore samples shows that the ore,beresite and fault gouge in Zhaoping fault zone are low-resistance bodies,which have an obvious difference from the m etamorphic rocks of Jiaodong group and Linglong granite in the hanging wall and footwall.The obvious difference also provides basis for the effectiveness of MT magnetotelluric sounding.According to catenular low-resistance anomalies acquired by MT method in the deep,the boundary line between metaorphic rocks of Jiaodong group and Linglong granite is defined,which means the position of Zhaoping fault zone.The centre of low-resistance anomalies indicates the topical swell of fault zone and the favourable ore-forming positions.Eight prospecting targets are delineated according to spatial relations between element association anomalies of tectonic chemistry and resistance anomalies of magnetotelluric sounding.A gold orebody is discovered at the depth from 1 150 m to 1 450 m by drillings.