3D high-efficiency property inversion method for potential field data in ellipsoidal coordinate system and its application to South China Sea

Abstract

The method of property inversion for gravity and magnetic data in ellipsoidal coordinate system is more suitable for obtaining large-area physical structure of the Earth. We built a method of high-efficiency property inversion for gravity and magnetic data in ellipsoidal coordinate system to obtain the density and magnetic susceptibility structure and used the exchangeability and equivalence of the grids at the same latitude to improve the inversion efficiency; in addition, a volume weight function was introduced to suppress the influence of the difference in grid size caused by latitudinal variation to improve the precision. We also first derived the forward formula of magnetic anomaly in ellipsoidal coordinate system according to the Gauss–Legendre quadrature (GLQ) and Poisson's formula for inversion. The high-efficiency inversion method for gravity and magnetic data in ellipsoidal coordinate system was tested on theoretical models, which can better restore the property distribution of the source, improve the computing efficiency and reduce memory requirements. The method was applied to the gravity data of South China Sea to obtain the 3D density structure, and the boundaries of ocean-continent transition were obtained based on the density and magnetic susceptibility variation characteristics. The results can better reveal the process of South China Sea expansion.