Inhomogeneous Magnetization of Tyrrhenian Seamounts Revealed From Gravity and Magnetic Correlation Analysis.

Barone, A.; Milano, M.; Fedi, M.

We perform a joint analysis of gravity and magnetic data sets in the Tyrrhenian Sea region to infer the rock physical properties of several volcanic seamounts. We propose a moving‐window application using Poisson's theorem, which relates the total gradient of the magnetic field to the total gradient of the first‐order vertical derivative of the gravity field data. In volcanic environments, where strong intensity of remanent magnetization is expected, the total gradient of the magnetic field is particularly useful since it is almost independent on the direction of the total‐magnetization. The moving‐window approach resulted necessary due to the heterogeneous magnetization distribution of the volcanoes. First, we perform synthetic tests based on realistic seamount models which exhibit inhomogeneous magnetization intensity and orientation. Using the total gradients, we demonstrate that our approach can provide an appropriate magnetization‐to‐density ratio in different subareas of seamounts. The results of the correlation analysis for the Palinuro, Marsili, Vavilov, and Magnaghi seamounts provide interesting information on the variability of magnetization associated with different epochs of formation and demagnetization effects due to hydrothermal alteration processes. Plain Language Summary: We analyzed gravity and magnetic data sets to determine the rock properties of the main seamounts in Southern Tyrrhenian Sea. This study shows that the correlation analysis based on a window‐by‐window approach is an efficient tool for studying potential field anomalies in areas where inhomogeneous distribution of magnetization is expected. We also show that, by studying the total gradients of the magnetic field and the first order vertical derivative of the gravity field, the correlation analysis is almost insensitive to the direction of the remanent magnetization. We obtain interesting information on the variability in magnetization for each seamount and identify possible areas of demagnetization due to hydrothermal alteration processes. Key Points: We may infer the rock magnetization of seamounts by the correlation analysis of gravity and magnetic anomaliesThe study of the potential field total gradients is particularly useful when the source has strong remanent magnetizationWe found inhomogeneous magnetization in the Palinuro, Marsili, Magnaghi and Vavilov seamounts, likely due to hydrothermal activity

REMANENCE; HYDROTHERMAL alteration; MAGNETIC fields; ROCK properties; SEAMOUNTS

Journal of Geophysical Research. Solid Earth, 2024, Vol 129, Issue 9, p1

2169-9313

Academic Journal

10.1029/2024JB028977