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›› 2015, Vol. 32 ›› Issue (3): 356-362.DOI: 10.7523/j.issn.2095-6134.2015.03.010

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Densities and compressibilities of calcium-carbonate melts under the mantle condition

LIU Zairong1,2, ZHANG Zhigang1   

  1. 1. Key Laboratory of Earth and planetary physics, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China;
    2. University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2014-05-07 Revised:2014-06-09 Online:2015-05-15

Abstract:

Carbonate melts play important roles in the carbon cycle process in the earth interiors. However, the previous studies were limited to the low temperature and low pressure conditions, and mainly focused on K+ and/or Na+ bearing carbonate melts. In this study we used extensive first-principle molecular dynamics simulation to obtain the equation of state of CaCO3 melts under the mantle condition. The results are listed in the following. CaCO3 melts have significantly greater compressibility than aragonite or typical silicate melts and hence the densities rapidly increase with pressure. When the pressure exceeds 10 GPa, densities of CaCO3 melts are higher than that of albite melt and the densities are even higher than that of diamond (at the pressure above 37 GPa). Densities of CaCO3 melts are lower than that of crystalline phase throughout mantle condition, but the density difference between them significantly decreases when the pressare increases. The high compressibility of CaCO3 melts may have important implications for uncovering distributions of carbonate melts in the mantle and for the formation of ultra-deep diamonds.

Key words: carbonate melts, first-principle molecular dynamics, density, compressibility

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