Shakya Abin, Ghosh Dipta B, Jackson Colin, Morra Gabriele, Karki Bijaya B
School of Electrical Engineering and Computer Science, Department of Geology and Geophysics, Center for Computation and Technology, Louisiana State University, Baton Rouge, LA, 70803, USA.
Department of Earth and Environmental Sciences, Tulane University, New Orleans, LA, 70118, USA.
Sci Rep. 2024 Aug 13;14(1):18739. doi: 10.1038/s41598-024-69873-8.
The earth is thought to have gone through complex physicochemical changes during the accretion and magma ocean stages. To better understand this evolution process at the fundamental level, we investigate the behavior of a bulk earth melt system by simulating the composition FeMgSiO (in wt%) at high pressure. A deep neural network potential trained by first-principles data can enable accurate molecular dynamics simulation of large supercells that greatly enhances sampling for reliable evaluation of elemental partitioning. Our simulated system undergoes a phase separation in which the four elements clump together to different extents into two major domains. Based on the coordination and space-decomposition analyses, the inferred composition at 3000 K and 29.1 GPa contains 96.2, 0.1, 1.9 and 1.7 wt% of Fe, Mg, Si, and O, respectively, for the one domain and the corresponding elemental proportions are 3.0, 29.7, 22.0, and 45.3 wt% for the other domain. The predicted segregation thus leads to the formation of an iron-rich phase which corresponds to the metallic core and a magma ocean phase which corresponds to the silicate mantle. The metallic domain incorporates more silicon and more oxygen whereas the magma ocean domain gains more iron oxides at higher temperatures. Our predicted compositions compare favorably with those derived from experimental work for the equilibrium state metal and silicate reacting under high-pressure conditions.
据认为，地球在吸积和岩浆海洋阶段经历了复杂的物理化学变化。为了在基础层面更好地理解这一演化过程，我们通过在高压下模拟FeMgSiO（重量百分比）成分来研究整体地球熔体系统的行为。由第一性原理数据训练的深度神经网络势能够对大型超胞进行精确的分子动力学模拟，这大大增强了采样，以便可靠地评估元素分配。我们模拟的系统经历了相分离，其中四种元素在不同程度上聚集在一起形成两个主要区域。基于配位和空间分解分析，在3000K和29.1GPa下推断的一个区域的成分分别包含96.2、0.1、1.9和1.7重量百分比的铁、镁、硅和氧，另一个区域相应的元素比例分别为3.0、29.7、22.0和45.3重量百分比。因此，预测的偏析导致形成一个对应于金属核的富铁相和一个对应于硅酸盐地幔的岩浆海洋相。金属区域包含更多的硅和更多的氧，而岩浆海洋区域在较高温度下获得更多的铁氧化物。我们预测的成分与在高压条件下平衡态金属和硅酸盐反应的实验工作得出的成分相比具有优势。
