New Magnetic Anomaly Map of the East Asia with Some Preliminary Tectonic Interpretations


Magnetic data provides basic information for geological and geophysical interpretation. In this study we compile recently collected (57 cruises survey) and old (published and open access) magnetic data. This compilation includes land, marine and aeromagnetic data acquired in the East Asia region. The newly acquired magnetic data are mainly concentrated mainly in the South China Sea (SCS) (especially in the northern continental shelf), the northwestern part of the West Philippine Basin (WPB), and the East China Sea. The updated magnetic dataset is gridded with a spacing of one arc-minute. The new mag- netic map provides new insights into the tectonic setting of East Asia. Analysis of the compiled data reveals several regional anomaly patterns: (1) the NE-SW trending high positive magnetic anomaly zone extending from southwest Taiwan to the area about 114.5°E and 22°N is pronounced; but it is less continuous southwest of the Penghu islands. In addition, the orientation of this high linear magnetic zone changes slightly in 118.5°E, 22.5°N from N60°E - N50°E. (2) Between the Gagua Ridge (GR) and the Luzon-Okinawa Fracture Zone (LOFZ) the marine magnetic stripes of the WPB exhibit a NW-SE orientation. This suggests that the seafloor spreading could be related to the first stage of the WPB east of the LOFZ. (3) The Urdaneta and Amami plateaus are associated with high magnetization zones. These high magnetization zones extend northwestward and are subducting beneath the Ryukyu Trench.

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