小秦岭地区矿田构造深部探测初步认识

The preliminary understanding of deep structure exploration in the orefield of Xiaoqinling area

通过地震剖面、钻孔资料对比,利用1∶5万重力资料和广域电磁测深资料对小秦岭地区矿田构造深部特征进行了探讨。初步认为:小秦岭地区太华群埋深1500、2500、3500 m处是重要的构造界面,特别是1500 m处可能限制了大多数的石英脉矿体就位,1500~2500 m网格状电磁剖面南倾、北倾视电阻率交汇部位有可能形成较大规模金矿体;巡马道断裂结构复杂,其上盘可能以构造片岩、碎裂岩为主,3500 m深部可能存在燕山期侵入岩体,具有寻找石英脉型金矿的前景,又具备形成构造蚀变岩型金矿的条件;太要断裂呈"阶梯状"北倾,其北1.5~3 km范围内,第四系下伏太华群埋深在800~1500 m,该断裂西宽东窄,东西两段断距存在差异;提出了该地区深部找矿应重点关注巡马道断裂中西段两侧电性结构特征复杂地段的认识。

According to the measured gravity data and wide-area magnetotelluric sounding study as well as the seismic section and borehole data,the authors investigated the deep structure of Xiaoqingling area.It is considered that the buried depths at 1500 m,2500 m and 3500 m of Taihua Group in Xiaoqingling area are important tectonic interfaces,especially at 1500 m,which may limit the emplacement of most quartz vein orebodies.The intersection of the S-dipping and N-dipping resistivity of the grid magnetotelluric profile at 1500~2500 m may indicate the formation of large-scale gold orebodies.The fault structure of Xunmadao is complex,and its upper plate may be dominated by structural schist and rifting rocks.The Yanshanian intrusive rock mass may exist at the depth of 3500 m,which has the prospect of finding quarz vein-type gold deposits and the conditions for forming tectonic alteration rock-type gold deposits.The Taiyao fault dips northward in the stepladder form.Within the range of 1.5~3 km to the north,the underlying Quaternary Taihua Group is buried at the depth of 800~1500 m.The fault is wide in the west and narrow in the east.The deep prospecting in this area should pay attention to the recognition of the complex structural features of the electrical structure on both sides of the middle and western sections of the Xunmadao fault.