Application of a multiple transmitter spacing gradient array TDIP survey in the Huaniushan mining area, Gansu...

Time domain induced polarization (TDIP) method is an important geophysical exploration technique for metal exploration. It is common to collect resistivity/IP data using a gradient array. However, the depth of investigation of a typical gradient array survey is limited by a single fixed transmitter electrode distance, which only provides information over a limited range of depths. In recent years, with the development of high-power transmitters, we have modified the single transmitter bipole gradient array to include several transmitter electrode spacings. This array design takes advantage of both the mapping characteristics of the gradient, with improved depth information. Therefore, it provides a possible means of detection for deep exploration of metal ore in perennial arid areas such as the Gobi Desert area, where building a large number of good transmitter locations is difficult. We applied this method in the Huaniushan mining area of Gansu Province in China. The results show that using multiple transmitter lengths allowed us to efficiently obtain both resistivity and IP anomalies at different depths in the research area. We have developed and use a 3D inversion routine to process and then image on these data sets. Finally, we combined the electrical structure determined from the multi-transmitter gradient surveys with relevant geological data. A 3D geological-geophysical model was constructed, which is consistent with the known location of a mineralised zones in the mining area and led to the speculation of eight new potential mineralisation. The application has shown significant effectiveness.