Enhancing Boundary Estimation of Potential-Field Data Using Tilt and Theta Angle Derivatives

Authors

Faculty of Mining Engineering and Metallurgy, Yazd University, Iran.

Abstract

Summary
This study evaluates the Tilt Derivative (TDR) and Theta Angle (Cos θ) filters for delineating geophysical anomaly boundaries and suppressing artifacts in potential-field data. Synthetic and real gravity/magnetic datasets were first corrected for magnetic inclination via Reduction-to-the-Pole (RTP), which, while improving anomaly focus, induced spurious artifacts. To address this, magnetic data were transformed into pseudo-gravity fields, neutralizing orientation-dependent effects and spectral distortions. Both TDR and Cos θ filters were then applied: TDR enhances edge detection by computing the ratio of vertical to horizontal gradients, while Cos θ identifies boundary zones through the cosine of the angle between total and horizontal gradients. On pseudo-gravity data, TDR and Cos θ yielded clearer structural boundaries and improved detection of shallow anomalies, particularly Anomaly 2 in the GolGohar, without RTP-induced artifacts. Directional dependency persisted in RTP-processed magnetic data for TDR, whereas Cos θ proved more orientation-invariant. In real gravity and pseudo-gravity datasets, both filters delineated boundaries independently of source trend, though TDR slightly exaggerated body widths. Random noise tests confirmed the numerical stability of each method. Integrating RTP, pseudo-gravity conversion, TDR, and Cos θ within a unified workflow substantially enhances boundary interpretation accuracy and robustness for mineral exploration in complex terrains.

Keywords

References

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Volume 11, Issue 2
September 2025
Pages 131-148

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