Abstract The time-domain induced polarization (TDIP) method is widely used in mineral exploration, particularly for sulfide metallic ores that exhibit strong polarization characteristics. By measuring the voltage after the current is switched off, TDIP can enable the detection of subsurface sulfide deposits. However, data interpretation in the field is often complicated by topographic variations and geological anisotropy, which can distort the observed responses. To enhance TDIP data interpretation, this study presents a three-dimensional forward modeling algorithm based on the finite element method (FEM), explicitly accounting for complex topography and anisotropy. The algorithm is validated using classical anisotropic models. Initially, we simulate TDIP responses of ore bodies with different geometries under flat topography. The results show that deposit orientation strongly affects TDIP profiles, with tilted and horizontally layered deposits yielding the most pronounced apparent chargeability responses. We then model the effects of sloped topography and anisotropy on TDIP measurements. The simulations indicate that as slope angles increase, the peak of the chargeability curve deviates further from the true deposit location, reducing apparent chargeability. Conversely, stronger anisotropy enhances the TDIP signal, improving the accuracy of deposit localization. Finally, a complex model incorporating both anisotropy and valley-like topography is examined using unstructured grids. The results reveal that vertical transverse isotropy (VTI) enhances TDIP responses, aiding in ore detection, whereas tilted transverse isotropy (TTI) presents greater challenges. This study provides valuable guidance for improving TDIP data interpretation in metallic ore exploration.
Hu et al. (Thu,) studied this question.