Extraction of Marine Magnetic Anomalies under Magmatic Disturbances Based on an Anisotropic Elliptical Directional Filter

Marine magnetic anomalies are of great significance to plate tectonics and geodynamics. However, the presence of magmatic disturbances does not allow a straightforward interpretation of marine magnetic anomalies. Therefore, we proposed an anisotropic elliptical directional filter to extract marine magnetic anomalies under magmatic disturbances. Synthetic marine magnetic anomaly models are built considering the magnetic layers of oceanic crust and upper mantle. The influence of magmatic disturbances of seamounts and magmatic intrusions and transform faults is investigated. The synthetic models and actual marine magnetic anomalies are used to investigate the effects of extracting marine magnetic anomalies. The results show that marine magnetic anomalies were effectively extracted by the elliptical directional filter. The power spectrum of the marine magnetic anomalies is anisotropic and is distributed in a narrow zone in the direction perpendicular to the strike of the marine magnetic anomalies. In contrast, the power spectrum of the magnetic anomalies of magmatic disturbances such as seamounts and magmatic intrusions is radially isotropic. Transform faults offset marine magnetic anomalies and cause the power spectrum to scatter in the direction parallel to the strike of the marine magnetic anomalies. Residual magnetic anomalies derived from the original magnetic anomalies subtracting the extracted magnetic anomalies enabled the separation of the magnetic anomalies of magmatic disturbances. If transform faults existed, the magnetic anomalies of the transform faults were also able to be separated by the residual magnetic anomalies. The application of the elliptical directional filter in the West Caroline Basin improved the continuity of the magnetic stripes and delineated three anomalous zones with magmatic disturbances.