K–Ar ages of the Akan-Shiretoko volcanic chain lying oblique to the Kurile trench: Implications for tectonic control of volcanism |
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| Authors: | Yoshihiko Goto Atsushi Funayama Nobuo Gouchi and Tetsumaru Itaya |
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| Institution: | Department of Geoscience and Technology, Graduate School of Engineering, Tohoku University, Aramaki, Aoba, Sendai 980-8579 (email:;Pacific Consultants Co. Ltd, 2-7-1, Nishi-shinjuku, Shinjuku, Tokyo 163-0730,;Shiretoko Museum, Motomachi, Shari, Hokkaido 099-4113, and;Research Institute of Natural Sciences, Okayama University of Science, 1-1, Ridai-cho, Okayama 700-0005, Japan |
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| Abstract: | The Akan‐Shiretoko volcanic chain, situated in the Southwestern Kurile arc, consists mainly of nine subaerial andesitic stratovolcanoes and three calderas. The chain extends in a SW–NE direction for 200 km, situated oblique to the Kurile trench at an angle of 25 degrees. Thirty‐seven new K–Ar ages, plus previous data, suggest that volcanic activity along the Akan‐Shiretoko volcanic chain began at ca 4 Ma at Akan, at the southwestern end of the chain, and systematically progressed northeastward, resulting in the southwest‐northeast‐trending volcanic chain. This spatial and temporal distribution of volcanoes can be explained by anticline development advancing northeastward from the Akan area, accompanied by magma rising through northeast‐trending fractures that developed along the anticlinal axis. The northeastward development of the anticline caused uplifting of the Akan‐Shiretoko area and changed the area from submarine to subaerial conditions. Anticline formation was likely due to deformation of the southwestern Kurile arc, with southwestward migration of the Kurile forearc sliver caused by oblique subduction of the Pacific plate. The echelon topographic arrangement of the Shiretoko, Kunashiri, Etorofu and Urup was formed at ca 1 Ma. |
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| Keywords: | Akan-Shiretoko volcanic chain echelon Hokkaido Japan K–Ar ages Kurile arc Quaternary tectonics volcanoes |
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