布里奇曼石巨晶驱动岩浆海洋分离的潜力
近日，西北工业大学牛海洋团队发现了布里奇曼石巨晶驱动岩浆海洋分离的潜力。这一研究成果发表在2026年1月21日出版的《自然》杂志上。
地球早期地幔可能以剧烈对流的深层岩浆海形式存在，其固化过程被认为是行星长期化学与动力学演化的核心环节。然而一个重要不确定性在于布里奇曼石（下地幔主要矿物相）的晶粒尺寸——其在极端压力下的成核行为始终难以通过实验直接观测。
研究组结合尖端技术手段，包括基于机器学习势函数驱动、包含多达100万个原子的大尺度分子动力学模拟，以及晶种植入与增强采样技术，首次揭示出MgSiO3布里奇曼石的晶体-熔体界面能随压力显著提升，可达常压硅酸盐-液态体系界面能的十倍。在深部基底岩浆海中，这种增强的界面能与可能的缓慢冷却过程共同作用，或可促成异常粗大的布里奇曼石晶体形成，其尺寸可达厘米至米级。
此类潜在巨型晶体可能驱动高效的分异结晶过程，引发显著的化学分异与地幔压实效应。若该机制确实存在，将为联系下地幔物质属性与早期地球分层结构提供新的物理路径，并推动未来地球动力学模型纳入过冷效应、成分对流与元素配分等关键要素。该研究由此提出一个连接微观成核过程与宏观行星结构的合理假说，为揭示地球内部初始成分结构的形成机制提供了新的理论视角。
附：英文原文
Title: The potential for bridgmanite megacrysts to drive magma ocean segregation
Author: Deng, Jie, Hu, Junwei, Shi, Yidi, Lee, Jina, Niu, Haiyang, Stixrude, Lars
Issue&Volume: 2026-01-21
Abstract: Earth’s early mantle probably existed as a deep, vigorously convecting magma ocean, and its solidification is considered central to the long-term chemical and dynamical evolution of the planet. Yet a notable uncertainty is the grain size of bridgmanite—the dominant lower-mantle phase—whose nucleation behaviour at extreme pressure has remained experimentally inaccessible. Here we show, using a combination of cutting-edge techniques, including large-scale molecular dynamics simulations consisting of up to 1million atoms driven by machine learning potentials (MLPs), seeding and enhanced sampling, that crystal–melt interfacial energies of MgSiO3 bridgmanite increase substantially with pressure, surpassing those of silicate–liquid systems at ambient pressure by a factor of up to ten (refs.1,2,3). In a deep basal magma ocean (BMO), this amplified interfacial energy, combined with the potential sluggish cooling, may permit the formation of unusually large bridgmanite crystals, up to centimetre-to-metre-scale sizes. Such potentially large crystals could drive efficient fractional crystallization and cause substantial chemical differentiation and mantle compaction. If operative, this mechanism would provide a new physical pathway linking lower-mantle material properties to early Earth stratification and it motivates future geodynamic models that explicitly incorporate supercooling, compositional convection and elemental partitioning. Our findings thus offer a plausible hypothesis connecting microscopic nucleation processes with macroscopic planetary structure, refining present views of how the Earth’s interior acquired its initial compositional architecture.
DOI: 10.1038/s41586-025-10063-5
Source: https://www.nature.com/articles/s41586-025-10063-5
