Early Miocene rotational process in the eastern part of south-west Japan inferred from paleomagnetic studies |
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| Authors: | Yasuto Itoh Kazuya Kitada |
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| Institution: | Department of Earth Sciences, College of Integrated Arts and Sciences, Osaka Prefecture University, Gakuencho 1-1 Sakai, Osaka 599-8531, Japan (email: ) and;Graduate School of Science and Technology, Kobe University, Rokkodai 1-1 Nada-ku, Kobe 657-8501, Japan |
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| Abstract: | Abstract This paper provides untilted paleomagnetic data obtained from the early Miocene strata around the Kanazawa‐Iozen area, in the eastern part of south‐west Japan. A thick pile of volcaniclastics and marine transgressive sediments underlie the area; they were deposited in the early stage of the Japan Sea opening event. Progressive thermal demagnetization tests isolated stable primary magnetic vectors from eight sites in the upper part of the Iozen Formation. Overall, the tilt‐corrected mean direction of this unit is D = 36.4°, I = 51.6° and α95 = 12.1. Together with a published paleomagnetic and chronological database, the present results suggest that clockwise rotation of south‐west Japan, linked to the back‐arc opening, commenced in the early Miocene and accelerated at the same time as rapid subsidence along the Japan Sea coast. Post‐opening, differential rotation within the eastern part of south‐west Japan is assumed, based on selected paleomagnetic data from the latest Early Miocene. |
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| Keywords: | back-arc opening clockwise rotation differential rotation Japan Sea paleomagnetism |
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