Joint Inversion Method of Gravity and Magnetic Analytic Signal Data With Adaptive Unstructured Tetrahedral Subdivision

Unstructured grid generation is more suitable for finishing the joint inversion of gravity and magnetic anomalies in the case of undulating observation surfaces and irregular field sources. To realize the joint inversion with an unstructured grid of gravity and magnetic anomalies corrupted by remanence, we proposed a joint inversion method of gravity and magnetic analytic signal (MAS) with an unstructured grid, and an adaptive subdivision method based on anomaly feature is introduced to improve the computation efficiency. The least-squares method was used to perform the computation of cross-gradient items in joint inversion for nonhomologous gravity and magnetic source. Synthetic tests on a dipping-slab model show that the proposed method can complete the joint inversion, and can effectively recover the distribution characteristics of the field source without precision loss, and can reduce calculation time and storage space. Finally, we applied our new method to real gravity and magnetic data to ascertain the distribution of magnetite in Shandong, China. We obtained the range of favorably mineralized regions based on the inversion results, which provides an important basis for further exploration.