Meeting room "Glova", 4 floor, Integrated Research Building
Abstract
Recent seismological studies have revealed that seismic structure of the base of mantle transition zone is complicated especially beneath subduction zones. In these reagions, the 660 km seismic discontinuity, which is the boundary between the mantle transition zone and the lower mantle, have been observed to be not a single discontinuity but to be multiplied into two or three discontinuities. The goal of our project is to understand this characteristic by petrological and mineralogical sciences. We will show experimental results of our recent studies: 1) phase relations in harzburgite; 2) phase diagram in Mg2SiO4, (Mg,Fe)2SiO4, and MgSiO3 using in-situ X-ray diffraction and ex-situ Raman spectroscopy; 3) phase relation in (Mg,Fe)SiO3; 4) metastable phase transformations in pyrolite. We would like to propose a hypothesis to explain the characteristics of the base of the mantle transition zone. The hypothesis is that the lower part of the mantle transition zone is composed partly of harzburgite. In the seminar, we would like to emphasize that difference of Al-content in rocks makes variety of its seismological features.
For inquiry：Taku Tsuchiya TEL:（089）927-8198
E-mail takut@sci.ehime-u.ac.jp
