Magnetic field imaging of ground–airborne transient electromagnetic data: a case study from Jinchuan Mine, China

Abstract The transient electromagnetic (TEM) method is widely applied in mineral exploration. The ground–airborne transient electromagnetic (GATEM) method offers higher efficiency and broader areal than conventional ground TEM surveys. However, when apparent resistivity is calculated directly from raw attenuation-voltage records, the interpretation may suffer from non‑uniqueness and ambiguity. To mitigate these issues, we develop a processing workflow that converts the raw attenuation-voltage data to magnetic field signals through an approximation algorithm developed in this study, Then the apparent resistivity is then calculated from the transformed magnetic field signals, which ensures the uniqueness of apparent resistivity. The full workflow is validated in a mining district in Gansu, China. Detailed lithological mapping provides the geological context, and the field data undergo systematic preprocessing before the proposed method is applied. The resulting GATEM apparent resistivity slices clearly delineate the three-dimensional distribution of ore bodies and coincides well with the local geological section. These results confirm that our workflow can effectively suppress noise, resolve non-uniqueness, and provide a reliable tool for interpreting raw GATEM data in complex environments.