中外学者发现全球核幔边界高速异常区内超低速区
近日，中外学者合作揭示了全球核幔边界高速异常区内存在超低速区。这一发现对理解地球深部物质循环和地幔动力学具有重要意义。
研究团队利用美国国家地震台网和中国地震台网的数据，对全球核幔边界高速异常区进行了详细成像。结果发现，在高速异常区内存在一个超低速区，其速度比周围区域慢约10%。
超低速区位于太平洋板块下方约2900公里处，延伸范围约为2000公里。研究团队认为，该超低速区可能是由部分熔融物质或富含挥发分的岩石组成，这些物质可以降低地震波的速度。
超低速区的发现表明，全球核幔边界高速异常区并非均匀的，而是存在内部结构差异。这为理解地球深部物质循环和地幔动力学提供了新的线索。
研究团队指出，超低速区可能是一个软弱区域，允许物质在核幔边界流动。这有助于解释太平洋板块的运动和地震活动。
该研究成果发表在国际学术期刊《自然·地球科学》上。参与研究的学者来自中国科学院地质与地球物理研究所、美国加州大学伯克利分校、德国马克斯·普朗克地球化学研究所等机构。
英语如下：
**Headline:** Oasis of Extreme Slowness Found Deep Inside Earth
**Keywords:**Core-mantle boundary, ultralow-velocity zone, anomalous zone
**Article:**
Scientists from China and abroad have discovered an ultralow-velocity zone within a high-velocity anomaly zone at the Earth’s core-mantle boundary. This discovery is significant for understanding the deep material circulation and dynamics of the Earth’s mantle.
Using data from the U.S. National Seismic Network and the China Seismic Network, the research team conducted detailed imaging ofthe high-velocity anomaly zone at the core-mantle boundary. They found an ultralow-velocity zone within the high-velocity anomaly, with velocities about 10% slower than the surrounding area.
The ultralow-velocity zone is located about 2,900 kilometers beneath the Pacific Plate and extends for about 2,000 kilometers. The research team believes that the ultralow-velocity zone may be composed of partially molten material or volatile-rich rocks, which can reduce the velocity of seismic waves.
The discovery of the ultralow-velocity zone suggests that the high-velocityanomaly zone at the core-mantle boundary is not uniform but has internal structural variations. This provides new clues for understanding the deep material circulation and dynamics of the Earth’s mantle.
The research team points out that the ultralow-velocity zone may be a weak zone that allows material to flow at the core-mantle boundary. This could help explain the movement of the Pacific Plate and seismic activity.
The research findings were published in the international academic journal Nature Geoscience. Scientists from the Institute of Geology and Geophysics, Chinese Academy of Sciences; University of California, Berkeley; and Max Planck Institute for Chemistry, Germany, participated in the research.
【来源】http://www.chinanews.com/gj/2024/03-06/10175367.shtml
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