Three-Dimensional Magnetic Inversion with Mixed Lp Norm Regularization for Constraining the Crustal Architecture of Mesozoic Volcanic Arc in the Northern South China Sea

The high-magnetic anomaly belt in the northern slope of the South China Sea has long been associated with a Mesozoic volcanic arc. However, its crustal architecture remains unclear, limiting the understanding of its geological implications. We assembled high-resolution reduced-to-the-pole aeromagnetic anomaly data around the northern South China Sea and then applied the 3-D magnetic inversion method based on mixed Lp norm regularization, with the constraint of multiple deep seismic reflection profiling data, to obtain high-resolution 3-D crustal susceptibility model. Our model confirms that the high-magnetic anomaly belt is caused by deep-seated magnetic bodies, which, supported by borehole and seismic data, are identified as a Mesozoic volcanic arc. We found that the Mesozoic volcanic arc described by high susceptibility bodies extends northeastward from the Dongsha Rise to Taiwan Island and primarily distributes within the depth range of 20~28 km. Our findings provide important constraints for understanding the pre-Cenozoic tectonic evolution of the northern South China Sea.