| Institution: | 1. Kobe Ocean-Bottom Exploration Center, Kobe University, Kobe, Japan
Department of Planetology, Kobe University, Kobe, Japan;2. Department of Planetology, Kobe University, Kobe, Japan;3. Faculty of Engineering and Design, Kagawa University, Takamatsu, Japan;4. Kobe Ocean-Bottom Exploration Center, Kobe University, Kobe, Japan;5. Institute of Earthquake and Volcano Geology, Geological Survey of Japan, AIST, Tsukuba, Japan;6. Institute for Integrated Radiation and Nuclear Science, Kyoto University, Osaka, Japan;7. Global Environment Disaster Prevention Department, Kochi University, Kochi, Japan |
| Abstract: | Ar-Ar ages, and petrographical and geochemical characteristics of pyroclastics and an overlying lava from Teshima Island, southwest Japan are presented. Although previous geological and age data suggested Teshima pyroclastics were products of magmatism > 3 my prior to lava flows of Setouchi volcanic rocks generated in association with southward migration of the southwest Japan arc sliver during opening of the Sea of Japan backarc basin at ~ 15 Ma, the present results led to the conclusion that a sequence of Setouchi volcanism, induced by slab melting and subsequent melt-mantle reactions, produced both pyroclastics and lava at 14.6–14.8 Ma. This age is oldest among those reported so far and may represent the timing of onset of characteristic Setouchi magmatism immediately posterior to and hence as a result of the mega-tectonic event including rotation of the southwest Japan arc sliver. |
