Journal of Mineralogical and Petrological Sciences
Online ISSN : 1349-3825
Print ISSN : 1345-6296
ISSN-L : 1345-6296
ORIGINAL ARTICLES
Decarbonation and melting in MgCO3–SiO2 system at high temperature and high pressure
Sho KAKIZAWAToru INOUEHideki SUENAMITakumi KIKEGAWA
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2015 Volume 110 Issue 4 Pages 179-188

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Abstract

The decarbonation reaction boundary and the melting temperature in the MgCO3–SiO2 system were investigated up to 26 GPa using a multi–anvil apparatus. It was found that the decarbonation reaction (MgCO3 + SiO2 → MgSiO3 + CO2) occurs below 8 GPa, but it becomes a melting reaction above 8 GPa. The melting system shows a simple eutectic relation. The eutectic point shifts to a higher temperature and more MgCO3–rich composition with increasing pressure. The eutectic temperatures at ~ 9 GPa and ~ 26 GPa were found to be ~ 1700 °C and ~ 2000 °C, respectively. Our results show that magnesite remains stable through the mantle geotherm, at least up to uppermost lower mantle, and that carbon can be transported to the lower mantle as magnesite. If a hot plume brings magnesite back to the upper mantle, it generates carbonatite magma or CO2 fluid.

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© 2015 Japan Association of Mineralogical Sciences
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