核幔边界D″区的地震学研究进展

核幔边界层在地球演化过程中扮演着极为重要的作用,是人们认识地球的主要研究对象之一。文中综述了近十多年来对核幔边界D″区开展地震学研究的主要方法及成果,内容涵盖了核幔边界D″区上部间断面、不均匀性、各向异性和超低速层等4个主要研究对象。结合多个相关学科的研究进展,从对热-化学-动力学三方面的耦合作用的分析,来探讨形成D″区各种观测现象的原因和机制,以及在此基础上提出的动力学演化模型。最后简要叙述了有关核幔边界研究的地震学、矿物实验、理论分析及计算科学的发展方向和挑战。随着对D″区认识的不断更新,逐步揭示地表观测到的可能受核幔边界因素控制的多种地质及地球物理现象。

The Earth's lowermost mantle and its seismological research progress

The core-mantle boundary(CMB) layer plays a significant role in the evolution of both the Earth's mantle and core. This paper outlines the generally used methods and vigorously debated results in seismological measurement about the core-mantle boundary and the D double prime region (or the Earth's lowermost mantle) during the last decades. The heterogeneity and anisotropy of the D″ discontinuity are discussed in detail, as well as those of the ultra-low velocity zones just above the core-mantle boundary. Mechanisms of observations in the D″ region are discussed using the coupling of thermal, chemical and dynamical factors, combining the research progresses of other disciplines; two dynamic models are proposed based on their coupling mechanism. The challenges for future research in seismological, mineral experiments, theoretical and computational geophysics have emerged. A reasonable model is necessary and expected to explain various Earth's surface observed geological, geochemical, and geophysical phenomena controlled by the lowermost mantle.