Multi-scale Apparent Magnetization Inversion Imaging Method Based on the Theoretical Pseudo-gravity Anomalies

The complex superposition of magnetic anomalies on the ground caused by multi-source magnetic geologic bodies makes it difficult to invert their geometries and positions. According to the theoretical pseudo-gravity anomalies of the Poisson formula of the gravity and magnetic field, this paper converts the magnetic anomaly dipole source into the centroid anomaly of unipolar source of the gravity, adopts the multi-scale interpolation cutting method to separate the anomaly and utilizes the iterative method to downward continue the multi-scale anomaly to the close-to-source depth of the top interface of each magnetic source so as to acquire the high-resolution magnetic anomaly near the top interface of each source. This magnetization inversion of the anomaly can greatly improve the inversion accuracy and speed. However, the continuation space is always required to meet the first type of boundary conditions of the Laplace equation, which leads to the fact that the close-to-source level may not really reflect the real depth of the anomaly which contains the equivalent effect of depth. Therefore, the method is essentially a fast apparent magnetization imaging method which describes the multi-source and multi-scale geological bodies. The increased vertical resolution may help to better define the magnetic interface morphology, and it can also obtain the physical property distribution of the multi-scale magnetic source geological body in three-dimensional space. The method is demonstrated on the synthetic models and on an aeromagnetic data set from the Xisha Trough, South China Sea.