Constraining Contact-Depth Solutions Through the Enhanced Horizontal Gradient Amplitude

Abstract

Accurate depth estimation is crucial for the quantitative interpretation of magnetic anomalies, which plays a significant role in geological mapping, mineral exploration and subsurface investigations. Traditional depth estimation techniques, such as the contact-depth (CD) and tilt-depth (TD) methods, often suffer from the generation of spurious solutions, especially when applied to complex geological environments. To address this, we propose an enhanced depth estimation technique, namely, the located contact-depth (LCD) method that integrates the CD technique with the enhanced horizontal gradient amplitude (EHGA). By utilizing points near the peaks of EHGA, a mask is generated to constrain the solutions from the CD method, effectively eliminating false solutions. Furthermore, a stable finite-difference technique for calculating vertical derivatives is used to improve the robustness and stability of the outputs. The proposed technique is tested on synthetic data, both with and without noise, as well as on real aeromagnetic data from the Galinge Fe-polymetallic deposit (China). The results demonstrate that our method provides depth estimates with improved reliability and accuracy compared to traditional methods, reducing the number of spurious solutions and enhancing precision around source boundaries. The result from the real example is in good agreement with known structures, highlighting the potential for deep mineral exploration in the Galinge Fe-polymetallic deposit.