R3: High-pressure science and deep Earth’s material

[R3-02] Rheological weakening induced by the olivine-ringwoodite transformation

[Presentation award entry]

*Rikuto Honda¹, Tomoaki Kubo¹, Yuichiro Mori², Yuta Goto¹, Takuya Iwasato³, Yuji Higo⁴, Masaaki Miyahara⁵ (1. Kyushu Univ., 2. U. Tokyo, 3. Shin-Nippon Nondestructive Inspection Co., Ltd., 4. JASRI, 5. Hiroshima Univ.)

Keywords:slab weakening, deep earthquake, transformation, in-situ X-ray observation, acoustic emission

To investigate Rheological Weakening and Shear Instability in deep slabs, we carried out the olivine (ol) - ringwoodite (rw) transformation experiments under uniaxial stress at 10-20GPa, 723-1273K, using a D111-type apparatus combined with X-ray and AE measurement system. We observed that the strength of Rw newly transformed was very small compared to that of parental Ol (~10-20%) at large overpressure and low T conditions. The parental Ol also rheologically weakens as the transformation proceeds probably because the fine grained weak Rw is interconnected.