Presentation Details
Ultralow velocities of amorphous CaCO3 and the origin of seismic anomalies in the Earth's upper mantle
ID：76
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Updated Time：2021-06-07 16:31:31 Hits：2276
Oral Presentation
Start Time：2021-07-10 16:40（Asia/Shanghai）
Duration：15min
Session：S8 8、地球物理 »
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Abstract
Volatiles (H2O, CO2, etc.) modulate the global climate in geological time. Hydrous minerals and fluids have been predominantly believed to be the major cause of the seismic low velocity, electrical conductivity abnormalities, deep earthquake, partial melting, and magma chamber for volcanoes in the upper mantle. By contrast, the effect of CO2 carriers has largely been underestimated. Calcium carbonate (CaCO3) is a major long-term host for CO2 and the nature of CaCO3 at extreme pressure-temperature (P-T) conditions are indispensable to decipher its circulation between the Earth's interior and its surface via volcanoes and subduction. Using the pulse-echo-overlap method in a Paris-Edinburgh press coupled with X-ray diffraction, we explored the seismic velocities of CaCO3 and observed an anomalously drop associated with aragonite to amorphous phase transition under P-T conditions relevant to subducting slabs in the upper mantle. Compared to aragonite, the velocity reductions of the partially amorphous CaCO3 are approximately 35% and 52% for compressional (VP) and shear (VS) wave velocities, respectively, at 3.5–5.5 GPa and 1,073–1,373 K. The VP and VS values of the partially amorphous CaCO3 are about 1/2 and 1/3 of those of the upper mantle minerals, respectively. Amorphous CaCO3-bearing domains would be expected to dwell atop the subducting slabs and naturally account for many enigmatic characteristics of the low-velocity layers in circum-Pacific subduction zones.
Keywords
deep carbon recycle,amorphization,high pressure,low velocity zone,sound velocity
Speaker
侯明强
中国科学院精密测量研究院Submission Author
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Important Date
-
Conference Date
Jul 09
2021
toJul 11
2021
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May 30 2021
Abstract Submission Deadline
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May 30 2021
Draft paper submission deadline
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May 30 2021
Early Bird Registration
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Jul 10 2021
Registration deadline
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Jul 11 2021
Contribution Submission Deadline
Sponsored By
青年地学论坛理事会
Organized By
中国科学院地球化学研究所
贵州大学
贵州大学
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