时间域航空电磁、航磁在五龙沟金矿整装勘查区中的应用研究

Applications of time domain airborne electromagnetic and aeromagnetic in Wulonggou gold deposit exploration area

五龙沟金矿整装勘查区地处青藏高原中北部,开展地面电磁法难度大.以直升机为平台搭载VTEM系统,在整装勘查区东南缘开展了1∶1万时间域航空电磁、航磁测量,结果显示矿体航电异常明显,呈双峰、高时间常数和低阻特征;同时,矿体处于-60^-40 n T的负磁场梯度带上,周围可见局部升高5~10 n T的低幅磁异常.对该航电异常进行板状体反演,板状体埋深、规模和产状等参数与后续收集到的矿体产状等信息基本一致,表明该方法对已知构造蚀变岩型金矿反映好.结合地质、化探等资料,建立了构造蚀变岩金矿的找矿模型,圈定了靶区6片,其中1片经钻孔验证发现隐伏矿体.时间域航空电磁、航磁对构造蚀变岩型金矿找矿效果好,能克服地面电磁法受制于高海拔、复杂地形等恶劣条件影响的诸多困难,可用于勘查区已知矿区深边部和空白区的"攻深找盲"以及其他地区的金及多金属矿勘查工作.

A helicopter-borne VTEM electromagnetic and magnetic survey with scale 1： 10000 was flown over the southeast of the Wulonggou gold deposit exploration area which is located in the Qinghai Tibet Plateau and is not suitable to carry out the ground electromagnetic survey. Geophysical signatures characteristics of tectonic-altered rock type gold deposit were observed in the electromagnetic and magnetic data over the known deposit. The characteristics showed strong electromagnetic response,double peak in d B/dt profile and higher time constant values over the orebody while aeromagnetic（ ΔT） values was-60 ^-40 n T and appeared micro magnetic anomaly with ΔT values 5 ~ 10 n T around. Besides,the parameters of the plate, which inversed from some electromagnetic anomalies data such as depth,size and attitude,were corresponding to the known gold orebody. Integration with geology and geochemistry data helped to establish the tectonicaltered rock type gold deposit prospecting marks and identify 6 new potential targets for the following exploration. One of the targets was found the deep orebody after drilling. The above studies proved that the time domain airborne electromagnetic and aeromagnetic can explore tectonic-altered rock type gold deposit and overcome the difficulties due to high altitude,complex terrain conditions and so on. Briefly,this method can apply to explore mineralization around or deep district of known deposit and blank district in Wulonggou gold deposit exploration area and other regions.