北京高压科学研究中心
Center for High Pressure Science &Technology Advanced Research

6.1 TSE John

Structures, chemical reactivity and transport properties of Carbon Dioxide and Carbonates under the mantle conditions

John S. Tse1,2, Min Wu1,3, Xue Yong1, Yuanming Pan4 and Jiuchua Chen2

1 Department of Physics and Engineering Physics, University of Saskatchewan, Saskatoon, Canada

2 Center for High Pressure Science & Technology Advanced Research, China

3 College of Materials Science and Engineering, Zhejiang University of Technology, Hangzhou, China

4 Department of Geological Sciences, University of Saskatchewan, Saskatoon, Canada


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Carbonatitic and carbonated silicate melts generated from melting in the mantle are the chief agents for liberating carbon from the solid Earth and exert important controls on Earths deep carbon cycle. In this presentation, we report recent first-principles molecular dynamic studies of aqueous and calcium carbonate melts at ambient conditions and down to the mantle/core boundary.  The calculations reproduced the ultralow viscosity observed recently by experiments. Surprisingly, the StokesEinstein equation relating the viscosity and the diffusion coefficient was found to hold at high pressure even when the melt is no longer an ideal fluid. Structural changes predicted in aqueous carbonates and carbonate melts at high pressure and high temperature will be discussed. Possible chemical reactions between silica and carbon dioxide (CO2) were investigated.  It is found that encapsulated CO2 reacted readily at relatively low pressure. CO2 mixed well with silica in the melt and formed a solid upon cooling with disordered Si and C sites similar to the proposed but recently dispute cristobalite solid-solution structure.