Basement characteristics reflected by aeromagnetic data in the northern coastal zone of Taizhou

On the basis of the latest aeromagnetic data of the northern coastal zone of Taizhou, integrated interpretation is performed in this study by combining airborne gravity data, regional geology, and magnetic susceptibility information. According to different zone and block characteristics of the reduced-to-the-pole (RTP) aeromagnetic data, the magnetic field characteristics and related structural division are determined and described in detail. The variation in aeromagnetic field characteristics reflects tectonic movement, magmatic activity, and stratigraphic distribution, which further delineates the structural characteristics of the basement lithofacies, aeromagnetic anomaly characteristics, and distribution regularity of the magmatic rocks and faults. The Bohai coastal zone, located to the west of the Tancheng-Lujiang fault, is characterized by block-like positive aeromagnetic anomalies. The basement is composed of rocks of the Archean Qianxi, Anshan, and Taishan groups, as well as Paleoproterozoic metamorphic rocks. The area to the east of the Tancheng-Lujiang fault is dominated by variable negative aeromagnetic anomalies. The magnetic field is caused by the metamorphic rocks of the Anshan, Jiaodong, Liaohe, and Fenzishan groups, in addition to several intermediate-acid magmatic rocks. The block-like positive aeromagnetic anomaly in the coastal zone of the South Yellow Sea might be related to Archean metamorphic rocks, and the basement rocks are Proterozoic metamorphic. The dramatic changes in the aeromagnetic anomaly belts in the southern Jiangsu-Wunansha region and the Zhejiang-Fujian coast are attributed to the strong reformation of the Proterozoic metamorphic basement rocks of weak magnetism to Mesozoic-Cenozoic magmatic rocks. The coastal zone of the East China Sea is characterized by NNE positive and negative aeromagnetic anomalies, whereas the metamorphic basement is composed of metamorphic rocks of the Proterozoic Chencai Group. The positive aeromagnetic anomaly belt is a reflection of the magmatic rock belt. In summary, this study reveals the characteristics of basement lithofacies in airborne gravity and aeromagnetic fields, which provides an important reference for geological evolution and the division of tectonic units.