Ultralow velocities of CaCO3 and the origin of seismic anomalies in the Earth's upper mantle

Authors

Mingqiang Hou, University of New Mexico
Ming Hao, University of New Mexico
Jin Liu, Center for High Pressure Science and Technology Advanced Research
Xiaowan Su, Peking univers
Wen-Yi Zhou, University of New Mexico
Rostislav Hrubiak, HPCAT
Jin S. Zhang, University of New MexicoFollow

Publication Date

Summer 5-31-2021

Document Type

Dataset

Abstract

Calcium carbonate (CaCO₃) is a major host for CO₂ in the deep Earth. The physical and chemical properties of CaCO₃ at extreme pressure-temperature (P-T) conditions are indispensable to decipher the circulation of carbon between the Earth's interior and surface via volcanism and subduction. Using the pulse-echo-overlap method combined with Paris-Edinburgh press, we measured velocities of CaCO₃ and observed an anomalous drop associated with the amorphization of aragonite under upper mantle conditions. The compressional (V_P) and shear (V_S) wave velocities of the partially amorphized CaCO₃ are reduced by ~35% and 52% respectively, at 3.5–5.5 GPa and 1,073–1,373 K. The V_P and V_S of the partially amorphized CaCO₃ are ~1/2 and 1/3 of what are expected for typical upper mantle minerals. The ultralow velocities of CaCO₃ provide a possible alternative explanation for the slow seismic anomalies, such as the low-velocity layers atop the slabs, in the upper mantle.

Keywords

CaCO3, low velocity zone

Recommended Citation

Hou, Mingqiang; Ming Hao; Jin Liu; Xiaowan Su; Wen-Yi Zhou; Rostislav Hrubiak; and Jin S. Zhang. "Ultralow velocities of CaCO3 and the origin of seismic anomalies in the Earth's upper mantle." (2021). https://digitalrepository.unm.edu/eps_fsp/12