Skip to main content
eScholarship
Open Access Publications from the University of California

Temperature-induced amorphization in CaCO3 at high pressure and implications for recycled CaCO3 in subduction zones.

  • Author(s): Hou, Mingqiang;
  • Zhang, Qian;
  • Tao, Renbiao;
  • Liu, Hong;
  • Kono, Yoshio;
  • Mao, Ho-Kwang;
  • Yang, Wenge;
  • Chen, Bin;
  • Fei, Yingwei
  • et al.
Abstract

Calcium carbonate (CaCO3) significantly affects the properties of upper mantle and plays a key role in deep carbon recycling. However, its phase relations above 3 GPa and 1000 K are controversial. Here we report a reversible temperature-induced aragonite-amorphization transition in CaCO3 at 3.9-7.5 GPa and temperature above 1000 K. Amorphous CaCO3 shares a similar structure as liquid CaCO3 but with much larger C-O and Ca-Ca bond lengths, indicating a lower density and a mechanism of lattice collapse for the temperature-induced amorphous phase. The less dense amorphous phase compared with the liquid provides an explanation for the observed CaCO3 melting curve overturn at about 6 GPa. Amorphous CaCO3 is stable at subduction zone conditions and could aid the recycling of carbon to the surface.

Main Content
For improved accessibility of PDF content, download the file to your device.
Current View