日時 ： ２００９年１月３０日（金）17：00〜
場所 ： 愛媛大学理学部講義棟1F101室
要 旨
It is believed that the upper-to-middle part of the mantle transition zone consists of pyrolite, but the structure and composition of its lowermost part remains controversial. In the transition zone, majorite garnet is reported as a silicate rich garnet and also a major phase within the assumption of the pyrolite composition. Recent works suggested that phase transitions and chemical reactions between majorite garnet and perovskites could conciliate mineralogical results and seismological observations in the region of 660 to 720 km depth, especially in zone of variable temperatures and compositions like subducting slabs. We conducted an experimental study at HP-HT in the Ca-Al-Si-O system at the P,T conditions of the lowermost transition zone and upper part of the lower mantle. In those regions, the progressive formation of the CaSiO3 perovskite and the variation of aluminium content between garnets and perovskites are showed to give interesting information for the understanding of the nature of the region of the 660 km depth discontinuity.
問い合わせ先：土屋 卓久 TEL （089）927-8198
E-mail takut@sci.ehime-u.ac.jp
