Crustal Thermal Structure of the Brazilian Equatorial Margin Using Fourier and Continuous Wavelet Transforms: A Comparative Analysis Based on Different Magnetic Datasets

In this work, we calculated the Curie Point Depth (CPD) for the Brazilian Equatorial Margin using the Fourier and continuous wavelet (CWT) transforms considering a linear inversion for random and fractal magnetization models with four different magnetic datasets. After comparing our results with Curie maps reported by previous studies, we concluded that the more consistent Curie isotherm was obtained by applying the random model based on CWT to the Brazilian Equatorial Margin Magnetic Map dataset, a compilation of airborne and marine magnetic surveys complemented with magnetic anomaly data extracted from the World Digital Magnetic Anomaly Map in the deep-water oceanic domain. In addition, we estimated heat flow using CPD results and compare with a global heat flow model based on geothermal measurements. In the continental domain, Curie values range from 18 to 35 km, shallowing westwards until reaching anomalously 10 km in the Tocantins Province. In turn, the heat flow decreases eastwards from 88 to 58 mW/m(2) as the Curie depth increases within the continental crust. Meanwhile, in the deep-water oceanic domain, the heat flow is overall higher (between 72 and 87 mW/m(2)), indicating a younger and warmer oceanic crust, whereas the Curie isotherm is shallower, varying between 10 and 30 km. Even so, it is deeper than Moho, suggesting a magnetized lithospheric mantle.

Automated summary

In this study, Curie Point Depth (CPD) was calculated for the Brazilian Equatorial Margin using Fourier and continuous wavelet transforms, with a focus on random and fractal magnetization models. Results showed variations in heat flow and Curie isotherm depths between the continental and deep-water oceanic domains, indicating differences in geothermal characteristics and lithospheric mantle magnetization.