Japan Geoscience Union Meeting 2019

Presentation information

[E] Poster

S (Solid Earth Sciences ) » S-MP Mineralogy & Petrology

[S-MP29] Oceanic and Continental Subduction Processes

Tue. May 28, 2019 5:15 PM - 6:30 PM Poster Hall (International Exhibition Hall8, Makuhari Messe)

convener:REHMAN Ur Hafiz(Department of Earth and Environmental Sciences, Graduate School of Science and Engineering, Kagoshima University), Tatsuki Tsujimori(Tohoku University), Chin-Ho Tsai(Department of Natural Resources and Environmental Studies, National Dong Hwa University), Kazuaki Okamoto(Faculty of Education, Saitama University)

[SMP29-P07] Experimental modeling of eclogite and C-O-H fluid interaction in the subduction zones

*Nadezda Chertkova1, Shigeru Yamashita2, Hiroaki Ohfuji1, Tetsuo Irifune1, Hirokazu Kadobayashi1, Yoshitaka Yamamoto3 (1.Ehime University, Geodynamics Research Center, 2.Okayama University, Institute for Planetary Materials, 3.National Institute of Advanced Industrial Science and Technology)

The presence of volatile components controls melting relationships in the subducting oceanic plate and the overlying mantle wedge, affecting their physical properties and seismic observables. The major volatile species in the mantle low oxygen fugacity environment are considered to be H2O and CH4, as estimated for mantle xenoliths and C-O-H fluid speciation in equilibrium with diamond [1,2]. Experimental studies with the direct monitoring of phase assemblages and melting relationships in the silicate systems with C-O-H components can shed light on the processes, which take place in the subduction zones, and provide important data for interpretation of observed physical parameters.
In this study, we employed in situ spectroscopic methods in combination with the diamond anvil cell (DAC) technique for investigation of C-O-H fluid behavior and its influence on phase relationships in the eclogite–5.75H2O–CH4 system at temperatures up to 1000 degree C and pressures exceeding 5 GPa. We designed a new cell assembly for Mao-type symmetric diamond anvil cell with large optical access to the sample in order to make it suitable for infrared and Raman measurements directly at high-pressure and high-temperature conditions. Mineral phase assemblages, observed during experiments, are consistent with those described in the dry system of the similar basaltic composition [3]. At the same time, miscibility between aqueous and carbonaceous components in the fluid phase coexisting with silicate minerals was confirmed at temperatures above 800 degree C and pressures above 3.2 GPa.

[1] Shirey, S.B., Cartigny, P., Frost, D.J., Keshav, S., Nestola, F., Nimis, P., Pearson, D.G., Sobolev, N.V. and Walter, M.J. (2013) Rev. Mineral. Geochem., 75, 355-421.
[2] Belonoshko, A. and Saxena, S. (1992) Geochim. Cosmochim. Acta, 56, 3611-3626.
[3] Yasuda, A., Fujii, T. and Kurita, K. (1994) J. Geophys. Res.: Solid Earth, 99, 9401-9414.