Curie point depth from spectral analysis of magnetic data in Taiwan

This study constructs an integrated magnetic anomaly map of Taiwan and its vicinity that combines land magnetic data and marine magnetic data. The reduction to pole (RTP) correction method was applied to the integrated magnetic anomaly data. The corrected magnetic anomaly results for a region roughly 880 km in width and 660 km in length fit well with geological tectonic signatures and are used to estimate the Curie point isotherm. The adopted Curie point depth method provides a relationship between the 2-D FFT power spectrum of the magnetic anomalies and the depth of magnetic sources by transforming the spatial data into the frequency domain. The basal depth of the magnetic sources is calculated from the magnetic data. Finally, the Curie point depth of Taiwan is obtained. The highest value of 17 km is located in northern Taiwan, and the lowest value of 6 km is located at southern Taiwan and also has the highest thermal gradient of 88 °C/km. The Curie point depth is consistent with heat-flow measurements with correlation coefficient 0.62.