Cenozoic Volcanisms and Mantle Dynamics in Japan

Abstract

The Japanese Islands have experienced subduction of the old Pacific Plate and the young Philippine Sea Plate, as well as back-arc basin opening, such as at the Kurile basin, Japan Sea, Shikoku basin, and Okinawa trough. This paper summarizes progress in understanding mantle dynamics beneath Japan in the past ～10 years in terms of igneous petrology and geochemistry, seismology, and numerical simulation. The discussion is separated into four regions: Hokkaido, northeast and central Japan, southwest Japan （Chugoku and Shikoku districts） , and Kyushu, from northeast to the southwest. Now that a massive amount of volcanic eruption age data and high-resolution seismic analyses have been accumulated for every region, we can discuss mantle dynamics within mantle wedge and back arc mantle in more detail than in the 20 th century. Constraints related to water content, temperature, and melting process in the mantle from a natural sample are, however, still missing despite the importance of these factors when modeling mantle dynamics.

Abyssal Peridotite as a Component of Forearc Mantle: Inference from a New Mantle Xenolith Suite of Bankawa in the Southwest Japan Arc

“…Petrological and chemical characteristics of the host basalt are also described because Bankawa is a new locality of peridotite xenolith-bearing basalt and they have not been reported in detail. This study will also contribute to our understanding of the peculiar Cenozoic magmatism in the SW Japan arc [27,31,32].…”