日時 ： ２００９年１２月１１日（金）※16：30～
場所 ： 愛媛大学総合研究棟Ⅰ 4F 共通会議室（理学部構内）
要 旨
Water decreases the melting temperature of mantle minerals, and enhances the magma generation. The water content in magma should define as hydrous liquidus line in the silicate-H2O system, and the water content generated in a P-T condition must be unique. Therefore we have determined the water content in the hydrous magma generated along the representative mantle geotherm at pressures of 8-20 GPa to discuss the magma migration in the mantle.
Two starting materials, pyrolite-2.9 wt% and 8.3 wt% H2O, were used. High-pressure and temperature experiments were carried out using an MA-8 type (Kawai-type) apparatus at pressure of 10-20 GPa and temperatures of 1350-1620 oC, which correspond to geotherm at those pressures, in order to investigate the water content of the melt generated in hydrous pyrolitic mantle. The degree of melting was determined from 1) SEM image of the cross sections of the recovered samples, and 2) the mass balance calculation on the chemical compositions of the minerals and quenched melts measured by SEM-EDS. The calculated water content of melt generated at higher than 12 GPa was found to be almost constant at least up to 20 GPa. The present result suggests that the degree of melting and the water content in magma should be almost constant in the upwelling plume of the mantle transition zone .
問い合わせ先：土屋 卓久 TEL （089）927-8198
E-mail takut@sci.ehime-u.ac.jp
