Earth and Planetary Sciences Faculty and Staff Publications

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 (VP) and shear (VS) 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 VPand VS 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

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