Exploration of Deep Mineral Resources Using the SOTEM Method

Summary This study introduces the Short-Offset Transient Electromagnetic (SOTEM) method for deep ore exploration, representing a significant advancement over traditional electromagnetic techniques. While methods such as Controlled Source Audio-frequency Magnetotellurics (CSAMT) and Long-offset Transient Electromagnetics (LOTEM) are widely used in mineral exploration, they are often constrained by depth limitations and resolution issues stemming from plane-wave field assumptions and signal strength challenges. The SOTEM approach employs a ground wire source with bipolar currents and utilizes shorter offsets—ranging from 0.3 to 2 times the detection depth. This innovation enhances signal strength, reduces noise interference, and minimizes averaging effects. To improve data interpretation accuracy, the adaptive regularized inversion algorithm (ARIA) is applied. A case study conducted at the Xiaoshan Mine in northern China demonstrates the practical application of SOTEM. Survey lines successfully identified high-resistivity formations and potential mineralization zones. Results indicate that SOTEM offers high detection accuracy and deep penetration capabilities, making it particularly effective in complex terrains, such as mountainous regions. Key advantages include increased signal strength, enhanced resolution, reduced transmitter power needs, and improved efficiency for deep-mining applications. The Xiaoshan case confirmed the successful detection of mineralization anomalies, highlighting the method’s suitability for deep geological exploration.