Study notes on water and magmas in the depths of the Earth

Abstract

I started my research as a petrology student supervised by Shohei Banno and Yoshiyuki Tatsumi at Kyoto University. I described every phenocryst in a single thin section to explain enigmatic plagioclase morphology and obtained PhD by discussion of processes in chemically-zoned magma chamber. I started high-pressure and high-temperature (HPHT) experiments as a postdoc at Ikuo Kushiro's lab at Tokyo, where I conducted partial melting experiments of hydrous mantle peridotite with Kei Hirose and duplicated andesite-dacite-rhyolite magmas by crystal fractionation of hydrous arc basalts. Then I joined the Depths of the Earth lead by John Holloway at Arizona State University (USA) and became the first Japanese who learned how to use multi-anvil type HPHT apparatus in the States. I proposed a choke point of subducting hydrous minerals, hydrous mantle transition and generation of komatiite and kimberlite magmas. After I learned Bassett-type diamond anvil cell from Helene Bureau, Nikolay Zotov, and Hans Keppler at Bayerisches Geoinstitut (Germany), I moved back to Kyoto University. With Kenji Mibe, Masami Kanzaki, Shigeaki Ono, and Kyoko Matsukage, I determined critical endpoints between various magmas and aqueous fluids by use of X-ray radiography and suggested new hypothesis for subduction zone magmatism. I have found seawater-like saline fluid inclusions in mantle xenoliths beneath Pinatubo and others, proposing the importance of being salty in subduction zone fluids.