Japan Geoscience Union Meeting 2018

Presentation information

[EE] Oral

S (Solid Earth Sciences) » S-IT Science of the Earth's Interior & Tectonophysics

[S-IT22] Interaction and Coevolution of the Core and Mantle in the Earth and Planets

Tue. May 22, 2018 3:30 PM - 5:00 PM International Conference Room (IC) (2F International Conference Hall, Makuhari Messe)

convener:Tsuyoshi Iizuka(University of Tokyo), Hidetoshi Shibuya(Department of Earth and Environmental Sciences, Faculty of Advanced Science and Technology, Kumamoto University), Taku Tsuchiya(愛媛大学地球深部ダイナミクス研究センター, 共同), Kenji Ohta(Department of Earth and Planetary Sciences, Tokyo Institute of Technology), Chairperson:Ohta Kenji, Kamada Seiji(FRIS, Tohoku Univ.)

4:15 PM - 4:30 PM

[SIT22-10] Sound velocities of CaSiO3 perovskite and some implications for deep mantle mineralogy

*Tetsuo Irifune1, Steeve Gréaux1 (1.Geodynamics Research Center, Ehime University)

Keywords:mantle transition region, lower mantle, sound velocity

We have measured sound velocities of CaSiO3 perovskitel (CaPv) under the entire pressure and temperature conditions of the mantle transition region by a combination of in situ X-ray observations and ultrasonic measurements in multi-anvil apparatus. Elastic properties of both tetragonal and cubic forms of CaPv have been obtained, yielding the shear modulus of cubic CaPv substantially lower than the theoretically predicted value. The present results, combined with the corresponding elastic properties of other high-pressure forms of major minerals in the mantle and subducting slabs, suggest the exsitence of a harzburgite-rich region near the bottom of the mantle transition region. In contrast, basaltic compositions should have significantly lower shear velocities relative to the surrounding pyrolitic mantle, and may explain the low velocity region atop of the lower mantle and the seismic scatterers in the uppermost lower mantle.