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

Mingqiang Hou; Qian Zhang; Renbiao Tao; Hong Liu; Yoshio Kono; Ho-Kwang Mao; Wenge Yang; Bin Chen; Yingwei Fei

doi:10.1038/s41467-019-09742-5

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

Nat Commun. 2019 Apr 29;10(1):1963. doi: 10.1038/s41467-019-09742-5.

Authors

Mingqiang Hou^{1

2}, Qian Zhang³, Renbiao Tao⁴, Hong Liu⁵, Yoshio Kono^{6

7}, Ho-Kwang Mao^{3

4}, Wenge Yang³, Bin Chen³, Yingwei Fei⁴

Affiliations

¹ Center for High Pressure Science and Technology Advanced Research, 201203, Shanghai, China. mingqiang.hou@hpstar.ac.cn.
² The Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA. mingqiang.hou@hpstar.ac.cn.
³ Center for High Pressure Science and Technology Advanced Research, 201203, Shanghai, China.
⁴ Geophysical Laboratory, Carnegie Institution of Washington, Washington, DC, 20015, USA.
⁵ CEA Key Laboratory of Earthquake Prediction, Institute of Earthquake Science, China Earthquake Administration, 100036, Beijing, China.
⁶ HPCAT, Geophysical Laboratory, Carnegie Institution of Washington, Argonne, IL, 60439, USA.
⁷ Geodynamics Research Center, Ehime University, Matsuyama, Ehime, 7908577, Japan.

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.

Publication types

Research Support, U.S. Gov't, Non-P.H.S.