JpGU-AGU Joint Meeting 2017

Presentation information

[EE] Oral

S (Solid Earth Sciences) » S-GC Geochemistry

[S-GC52] [EE] Volatile cycles in the Earth - from Surface to Deep Interior

Mon. May 22, 2017 10:45 AM - 12:15 PM A03 (Tokyo Bay Makuhari Hall)

convener:Takeshi Hanyu(Japan Agency for Marine-Earth Science and Technology, Department of Solid Earth Geochemistry), David R Hilton(University of California San Diego), Hirochika Sumino(Department of Basic Science, Graduate School of Arts and Sciences, The University of Tokyo), Yuji Sano(Division of Ocean and Earth Systems, Atmosphere and Ocean Research Institute, University of Tokyo), Chairperson:David Hilton(University of California San Diego), Chairperson:Takeshi Hanyu(Japan Agency for Marine-Earth Science and Technology, Department of Solid Earth Geochemistry)

11:45 AM - 12:00 PM

[SGC52-11] In situ optical study of H2O-CO2-CO system at high pressures

*Nadezda Chertkova1, Hiroaki Ohfuji1, Tetsuo Irifune1 (1.Ehime University, Geodynamics Research Center)

Keywords:Externally heated diamond anvil cell, Raman spectroscopy, C-O-H fluid

Externally heated diamond anvil cell (DAC) technique provides optical access to the sample, homogeneously heated to high temperatures, and is widely used for in situ observations and spectroscopic measurements. Nevertheless, the pressure range achievable with the conventional externally heated hydrothermal DAC is limited by low resistance of diamond anvils to thermal stress at high temperatures. In this study we used a modified external heating system combined with the lever type DAC (Whale cell) in order to reach simultaneous high temperatures and high pressures for in situ measurements.
Visual observations and Raman spectroscopy were carried out for C2H2O4 composition in the temperature range to 720 degree C and pressure range to 6.4 GPa. Above 105 degree C and 1 GPa a dissociation of starting material with the formation of CO2 solid, H2O and CO fluid phases was observed. At temperatures above 377 degree C and pressures above 2 GPa a polycrystalline phase was stable, which transformed to a solid carbon phase above 565 degree C and 5.5 GPa. Raman spectra of the solid carbon phase contain two broad peaks, consistent with the D breathing mode and G bond-stretching mode of C atoms. Therefore, solid phases are stable in this system in the broad region of temperatures and pressures.
Obtained results have interesting implications for transportation mechanism of water and CO2 into the Earth’s interior in cold subduction zones.