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

Authors

Mingqiang Hou, University of New Mexico
Ming HaoFollow
Jin Liu
Xiaowan Su
Wen-Yi Zhou, University of New Mexico
Jin S. Zhang, University of New MexicoFollow
Rostislav Hrubiak

Publication Date

2021

Document Type

Dataset

Abstract

Calcium carbonate (CaCO₃) is a major mineral host for CO₂ in deep Earth. The physical and chemical properties of CaCO₃ at extreme pressure-temperature (P-T) conditions are important for understanding the CO₂ circulation between the Earth's surface and interior primarily via volcanism and subduction. Using the pulse-echo-overlap method combined with Paris-Edinburgh (PE) press, we measured velocities of CaCO₃ under upper mantle conditions and observed an anomalous velocity drop associated with the amorphization of aragonite. 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_Pand V_S of the partially amorphized CaCO₃ are only ~1/2 and 1/3 of what are expected for typical upper mantle minerals. The ultralow velocities of CaCO₃ provide a plausible alternative explanation for the slow seismic anomalies in the upper mantle, such as the low-velocity layers atop the slabs.

Language (ISO)

English

Recommended Citation

Hou, Mingqiang; Ming Hao; Jin Liu; Xiaowan Su; Wen-Yi Zhou; Jin S. Zhang; and Rostislav Hrubiak. "Ultralow velocities of CaCO3 and the origin of seismic anomalies in the Earth's upper mantle." (2021). https://digitalrepository.unm.edu/eps_fsp/13