地球早期地幔化学不均一性及其成因机制

Chemical heterogeneity in the early Earth's mantle and its geodynamic genesis.

早期地球是地球科学前沿研究方向之一,涉及地-月形成、核幔分异、原始大气圈和水圈的形成等关键科学问题。地幔是硅酸盐地球的主要组成部分,也是地球上最大的化学储库,其早期演化为揭示早期地球增生、核-幔分异、壳-幔分异等重大地质事件提供重要制约。近年来,地球早期地幔不均一性逐渐被认知,本文在总结早期地幔不均一性的稀有气体同位素、钕同位素和钨同位素等证据基础上,探讨了早期地幔不均一性形成动力学机制,并指出发展高精度同位素分析技术,结合地球物理和实验岩石学,揭示核幔边界结构、核幔物质交换过程是深入研究早期地幔不均一的重要发展方向。

The early Earth is one of the frontier topics in Earth Sciences,involving numerous key scientific questions,such as the formation of moon-earth system,core-mantle differentiation,and formation of proto-atmosphere and hydrosphere.The mantle is the main component and the largest chemical reservoir of the Silicate Earth.The evolution of early mantle provides important constraints for revealing major geological events,such as accretion of the early Earth,core-mantle differentiation,and mantle-crust differentiation.Chemical heterogeneity in the early Earth mantle has been gradually discovered in recent years.On the basis of overview of the evidence of rare gas,neodymium and tungsten isotopes for the early mantle heterogeneity,this paper discusses the possible geodynamic processes(i.e.,early mantle differentiation,late accretion,and core-mantle interaction)to form the early mantle heterogeneity.Furthermore,it also points out that using the high precision isotopic data,combined with geophysics and experimental petrology,to reveal the structure of core-mantle boundary and the material exchange process between mantle and core is the important issue of the early mantle heterogeneity in the future.