CSAMT与AMT数据“拼接”处理——以湖南仁里铌钽矿床7号剖面为例

CSAMT and AMT data"splicing"processing:A case study of No.7 profile of the Renli niobium tantalum deposit in Hunan Province

音频大地电磁测深(AMT)与可控源音频大地电磁测深(CSAMT)均为深部勘查常用方法。AMT方法采集频带较宽,但存在“死频带”,在“死频带”范围无法完全得到地质体响应。CSAMT信噪比高,但通常受发射功率的限制,收发距离一般放置不够远,容易过早进入“近区”。本文展示了将两种方法数据拼接组合的一种处理方式:首先在前人理论研究的基础上,利用CSAMT和AMT均匀半空间模型进行了正演计算,结果表明,CSAMT远区与AMT数据拼接具有可行性;选择湖南仁里铌钽矿床7号剖面的野外实测数据进行实验,将同测点位置的CSAMT远区数据和AMT同测点同模式数据相“拼接”,合成新AMT数据;最后进行反演,反演结果与钻探结果对应较好,表明该方法具有一定的效果。

Generally,audio frequency magnetotelluric sounding(AMT)and controlled source audio frequency magnetotelluric sounding(CSAMT)are used for deep exploration.The AMT method has a relatively wide acquisition frequency band,but is affected by weak signals in certain frequency bands of the natural field,which is called"dead band".In the"dead band"range,the geological body response cannot be obtained completely.However,CSAMT has the characteristics of high signal-to-noise ratio due to the introduction of artificial source;therefore,due to the limitation of transmitting power,the distance between transmitting and receiving is generally not far enough,so it is easy to enter the"near area"prematurely.This paper proposes a processing method that combines the two methods of data splicing.Firstly,on the basis of previous theoretical research,the forward calculation is carried out by using CSAMT and AMT uniform half space model,and the results show that the combination of CSAMT and AMT data is feasible.Secondly,the field measured data of No.7 geological section of the Renli niobium and tantalum deposit in Hunan Province are tested by using the CSAMT far area data and the AMT data at the same measuring point with the same mode to"splice".Finally,the new AMT data derived from synthesization are used.The results show that the inversion results and the drilling results correspond well,which proves that the method has good promotion significance.