Magnetotelluric Study along a Profile Traversing the Korean Peninsula

Magnetotelluric measurements were carried out along a profile traversing the Korean peninsula, which is an important tectonic link between the continental block of China and the island arcs of Japan, to figure out the mid-crustal structure of electrical conductivity. The 2-D inversion result shows a few highly conductive anomalies and highly resistive anomalies. The highly conductive anomalies are related with the basement rocks of the Cretaceous Kyongsang basin and the sedimentary and metamorphic rocks of the Okchon belt that is a representative orogenic belt in the Korean peninsula, while the highly resistive anomalies are connected with the Cretaceous granite intrusions in the middle part of the Okchon belt and the eastern part of the Kyongsang basin. Another interesting feature is the large phase anomaly exceeding 90° in the Okchon belt. Although a reliable explanation seems to be made by an electrically anisotropic structure, it will be necessary to treat a full 3-D modeling or an anisotropic modeling to understand the complex structure of this region.