Melting and decomposition of MgCO3 at pressures up to 84 GPa
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Magnesium carbonate MgCO3 (magnesite) was experimentally studied at pressures of 12–84 GPa and temperatures between 1,600 and 3,300 K. We applied the high-pressure technique using a multianvil press and a diamond anvil cell with laser heating. The phase relations and melting of magnesite were investigated by means of Raman and time-resolved multi-wavelength spectroscopy. Magnesite is found to melt congruently within the entire studied pressure range at temperatures of 2,100–2,650 K. At temperatures above 2,700 K, we observed decomposition of magnesite with formation of MgO and a carbon phase (diamond). Our results demonstrate that at high pressures, the magnesium carbonate melt can exist at a wide range of thermodynamic conditions.
KeywordsMg-carbonate melting High-temperature decomposition boundary Phase relations High-pressure experiment Laser heating Raman spectroscopy
The study was financially supported by the German Research Foundation (DFG) and the Russian Foundation for Basic Research (Nos. 13-05-00835, 14-05-31142 and 11-05-00401). N.D. thanks DFG for financial support through the Heisenberg Program and the DFG Project DU 954-8/1.
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