Paleomagnetism and fission-track ages of Oki-Dogo Island in Southwest Japan

Takeshi Kojima, Makoto Okada, Hiroto Ohira, Katsuyasu Tokieda, Hiroaki Komuro, Kazuo Amano
2001 Earth, Planets and Space  
Zircon fission-track (F.T.) ages and paleomagnetic directions were measured on the Neogene series of the Oki-Dogo Island. The results of F.T. dating on the the Tokibariyama Formation show ages of 23.7 ± 1.3 and 20.0 ± 2.3 Ma, indicating the early Early Miocene. Paleomagnetic measurements of the Tokibariyama, Kori Formations (24-17 Ma) and the Oki Trachyte-Rhyolite (6.8 Ma) were done to reveal the movement of Oki-Dogo Island during the Japan Sea opening. The Tokibariyama and Kori Formations show
more » ... ori Formations show an average declination of 39.9 • . The Oki Trachyte-Rhyolite has the same average geomagnetic direction as the present day value. These results show that a clockwise rotation of 40 • ± 15 • of the Oki-Dogo Island occurred between 17 and 6.8 Ma which is similar to the main land of southwest Japan.
doi:10.1186/bf03352361 fatcat:gwq6rtuz7bclzi26v52r67oyhi