Meeting room "Glova", 4 floor, Integrated Researdh Building
Abstract
Major seismic discontinuities in mantle have been interpreted as phase transitions in olivine which is the most abundant mineral in the earth's mantle. 410-km, 660-km discontinuities, and the top of D" layer correspond to olivine-wadsleyite, post-ringwoodite, and post-perovskite transitions, respectively. In this decade, seismological studies have revealed that seismic discontinuities in mantle are more complex than expected in some regions. Simmons and Gurrola (2000) reported that presence of multiple seismic discontinuities near the base of the mantle transition zone (MTZ). They found that 660-km discontinuity is not a single discontinuity and that there are three discontinuities at 610, 660, and 720 km depth beneath North America. Deuss and Woodhouse (2001) reported that 520 km discontinuity can be observed and splitting of the discontinuity can be observed. In GRC, we have tried to interpret these regional seismic discontinuities by studying phase relations in rocks which can be present in MTZ. Our tool to study them is high PT equipment, Kawai-type apparatus. In this seminar, I would like to show results of our resent studies for phase relations in harzburgite under high pressure and temperature. Using these results, I introduce our interpretations for the splitting of 520-km discontinuities and 610-km discontinuity. In addition, I will show our future experimental projects to interpret 720-km discontinuity.
For inquiry：Taku Tsuchiya TEL:（089）927-8198
E-mail takut@sci.ehime-u.ac.jp
