法国巴黎城市大学Charles-Édouard Boukaré团队发现地幔的凝固不可避免地导致了基底岩浆海洋的形成。2025年3月26日，该研究成果发表在《自然》杂志上。

地幔深层地球物理结构的主要解释之一是，它们源于地核上方地球原始基底岩浆海洋的自上而下固化。然而，固体是首先在地幔底部形成，向上固化，还是在熔体上方向下固化，仍然存在争议。研究组表明，无论熔融曲线和地热在哪里相交，致密的富铁熔体与较轻的贫铁固体的重力分离都会驱动地幔演化。这一过程导致富含氧化铁的熔体在岩芯上方积聚，形成基底岩浆海洋。

他们使用一种新的多相流体动力学方法对地幔凝固进行了数值模拟，该方法结合了熔融相关系和地球化学模型。这使得他们能够估算原始地球化学储层的成分特征和空间分布，这可能与太古宙岩石中测量的同位素异常直接相关。结果发现，大量的固体是在地球表面产生的，而不是在深处，在深地幔中注入了浅硅酸盐分馏的地球化学特征。这项工作可以作为重新研究岩石行星演化最初10亿年地幔动力学、岩石学和地球化学之间复杂相互作用的基础。

附：英文原文

Title: Solidification of Earth’s mantle led inevitably to a basal magma ocean

Author: Boukar, Charles-douard, Badro, James, Samuel, Henri

Issue&Volume: 2025-03-26

Abstract: One of the main interpretations of deep-rooted geophysical structures in the mantle1 is that they stem from the top-down solidification of the primitive basal magma ocean of Earth above the core2,3,4,5,6. However, it remains debated whether solids first formed at the bottom of the mantle, solidifying upward, or above the melts, solidifying downward. Here we show that gravitational segregation of dense, iron-rich melts from lighter, iron-poor solids drives mantle evolution, regardless of where melting curves and geotherms intersect. This process results in the accumulation of iron-oxide-rich melts above the core, forming a basal magma ocean. We numerically model mantle solidification using a new multiphase fluid dynamics approach that integrates melting phase relations and geochemical models. This enables estimating the compositional signature and spatial distribution of primordial geochemical reservoirs, which may be directly linked to the isotopic anomalies measured in Archean rocks7,8,9,10,11. We find that a substantial amount of solids is produced at the surface of the planet, not at depth, injecting geochemical signatures of shallow silicate fractionation in the deep mantle. This work could serve as a foundation for re-examining the intricate interplay between mantle dynamics, petrology and geochemistry during the first thousand million years of the evolution of rocky planets.

DOI: 10.1038/s41586-025-08701-z

Source: https://www.nature.com/articles/s41586-025-08701-z