Joint inversion of potential field data by a modified cross‐entropy coupling function

Abstract The joint inversion of gravity and magnetic data presents a powerful solution to mitigate the inherent non‐uniqueness of potential field methods. This paper introduces a novel structural coupling approach for joint inversion based on a modified cross‐entropy function. The proposed stabilizer minimizes the divergence between the model distributions, thereby enforcing structural correlation, whereas a minimum‐entropy condition promotes sparsity to recover focused subsurface models. The non‐quadratic functional is transformed into a pseudo‐quadratic form, enabling an efficient solution via the reweighted regularized conjugate gradient method. A key advantage of this formulation is its independence from the results of standalone inversions or explicit petrophysical relationships. The method's efficacy is first demonstrated on two different synthetic models, where it yields more compact and structurally coherent models compared to separate inversions, accurately resolving the geometry and physical properties. The technique was subsequently applied to airborne gravity gradiometer and magnetic data from the Nikka volcanogenic massive sulphide deposit in Ontario, Canada. The joint inversion successfully delineated the No. 3 Lens, resolving its lower boundary at approximately 300 m depth with greater precision than individual inversions, which produced smoother and more diffuse anomalies. The results confirm that the modified cross‐entropy approach significantly enhances structural resolution and provides a robust tool for integrated geophysical interpretation, particularly in complex geological settings with limited prior information.