报告详情
Ultralow velocities of amorphous CaCO3 and the origin of seismic anomalies in the Earth's upper mantle
编号：76
访问权限：仅限参会人
更新：2021-06-07 16:31:31 浏览：764次
口头报告
报告开始：2021年07月10日 16:40（Asia/Shanghai）
报告时间：15min
所在会场：[S8] 8、地球物理 [S8-1] 8、地球物理-1
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摘要
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.
关键词
deep carbon recycle,amorphization,high pressure,low velocity zone,sound velocity
报告人
侯明强
中国科学院精密测量研究院稿件作者
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重要日期
-
会议日期
07月09日
2021
至07月11日
2021
-
05月30日 2021
摘要截稿日期
-
05月30日 2021
初稿截稿日期
-
05月30日 2021
提前注册日期
-
07月10日 2021
注册截止日期
-
07月11日 2021
报告提交截止日期
主办单位
青年地学论坛理事会
承办单位
中国科学院地球化学研究所
贵州大学
贵州大学
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