Applicability of airborne geophysics (DighemV) in a granite area, 2; Airborne magnetic and radiometric surveys

Hasegawa, Ken; Matsuoka, Toshiyuki; Yuki, Yoichi*

Airborne magnetic and radiometric surveys were conducted in the region of the Toki granite. The shaded relief map of the magnetic survey data shows that the magnetic susceptibility of the Toki granite is not uniform, and a relatively high magnetic susceptibility zone was identified. Moreover, it was shown that the Toki granite can be separated into three parts; one with high U abnormality, another with high Th abnormality, both separated by a middle region. The area with high magnetic susceptibility in the Toki granite correspond to where the thickness of the layer of the Mizunami and/or the Seto Group is thin and the depth of the Toki granite is shallow, and the region corresponds to high U abnormality. We conclude the Toki Granite is not homogeneous with respect to geophysical properties, but instead is composed of separate regions.