島弧-海溝系のテクトニクス  [in Japanese] Tectonics of arc-trench system  [in Japanese]

This paper refers briefly to the distinguished events in the dawn of Plate Tectonics theory in Japan and the recent developments on the tectonic evolution of NE Japan arc. The results obtained during the international Upper Mantle Project were published in 1973. Geologic sections through the Japanese Islands in the paper were not affected as a whole by the revolutional new concept. On the contrary, a paper received with international enthusiasm, MATSUDA & UYEDA (1971), exhibited the new understanding on the arc-trench system in Japanese Islands. Nevertheless, most of problems pointed out by them have been not worked out during the past 15 years. It is certain that the Neogene orogeny began after the age indicated by the Hawaiian-Emperor bend. Andesitic arc volcanism is characteristic of the initial stage and waned with volcanism in the forearc region about 22 Ma ago. The following stage began with basalt and dacite volcanism, bimodal, associated with E-W extensional regime. The anticlockwise rotation of NE Japan arc may be the event in this stage. The stress regime changed later to NE-SW compressional. The present situation in the NE Japan arc appeared probably about 5Ma ago and became strongly E-W compressional 2 Ma ago. Some papers applied the evolutional model of island arc suggested by UYEDA & KANAMORI (1978) to the NE Japan arc.