发表机构
State Key Laboratory of Geological Processes and Mineral Resources, School of Earth Sciences, China University of Geosciences; Institute of Atomic and Molecular Physics, Sichuan University; Bayerisches Geoinstitut, Universität Bayreuth（中国地质大学地球科学学院; 四川大学原子与分子物理研究所; 拜罗伊特大学巴伐利亚地质研究所）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该研究通过机器学习加速的分子动力学模拟，发现玄武质熔体在约3 GPa存在由铝配位重组驱动的粘度最小值，解释了软流圈熔体聚集及双重地震信号的物理机制。
AI 中文摘要
软流圈的力学软弱性使得板块构造成为可能，但其起源仍存在争议。部分熔融被认为是导致这种软化的原因，然而近期研究表明，玄武质熔体中测得的粘度最小值（对熔体流动性至关重要的控制因素）可能是实验假象。我们利用基于量子力学、机器学习加速的分子动力学方法，将模拟时间尺度延长了超过1000倍，并实现了百分级的精度。我们证明，玄武质熔体在约3 GPa压力下表现出稳健的粘度最小值（比1 bar值低约20%），这一现象由压力诱导的铝配位重组驱动，促进了剪切弛豫，而硅氧多面体保持结构刚性。我们的结果揭示了随深度变化的流变转变：熔体流动性在约150公里以下达到峰值，促进高效提取，但在上升过程中急剧下降，导致熔体在岩石圈下方停滞。该机制为熔体贫化的深层软流圈和岩石圈-软流圈边界附近富熔体层的双重地震信号提供了物理基础。
英文摘要
The asthenosphere's mechanical weakness enables plate tectonics, but its origin is debated. Partial melt has been proposed to cause this softening, yet recent studies suggest that the measured viscosity minimum in basaltic melts, an essential control on melt mobility, is an experimental artifact. Using quantum mechanics-based, machine learning-accelerated molecular dynamics, we extend simulation timescales by more than a factor of 1000 and achieve percent-level precision. We show that basaltic melt exhibits a robust viscosity minimum (approximately 20% below 1-bar values) at approximately 3 GPa, driven by pressure-induced reorganization of aluminum coordination that facilitates shear relaxation while silicon-oxygen polyhedra remain structurally rigid. Our results reveal a depth-dependent rheological transition: melt mobility peaks below approximately 150 km, promoting efficient extraction, but declines sharply during ascent, causing melt to stagnate beneath the lithosphere. This mechanism provides a physical basis for the dual seismic signatures of a melt-depleted deep asthenosphere and a melt-enriched layer near the lithosphere-asthenosphere boundary.
Comments14 pages, 2 figures
