The role of light elements at the core-mantle boundary – partitioning, demixing, and transport

轻元素在核幔边界的作用——分配、分层和传输

• 批准号: 521548786
• 负责人: Professor Dr. Ronald Redmer
• 金额: --
• 依托单位: Max-Planck-Institut für Sonnensystemforschung (MPS)
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/521548786?language=en
• 关键词: role; light; elements; core; mantle

The possible presence of a stagnant layer below the core-mantle boundary raises a number of important geophysical and geochemical questions for the deep Earth. In the proposed project, we plan to explore the possibility of this layer being caused by a distinct chemical composition, i.e., the accumulation of light elements there, initially brought to the core at higher temperature during core segregation. To this avail we will perform ab-initio simulations on different aspects that may lead to the formation and stability of such a light element enriched layer, and determine dynamically important physical properties of it. For the geodynamo and thermal evolution considerations in other projects proposed within the focus program, density, viscosity and thermal conductivity are of significance. We have agreed to collaborate with two other projects, Wicht and Zhu for the geodynamo, Tosi et al. for thermal evolution simulations. As an additional driving force for the geodynamo, especially in the young Earth, we will explore the possible exsolution of SiO2 from the initial core composition. In a more geochemical context, we will consider the transport of light elements to the core during its formation by equilibration between the magma ocean and metal, as well as the possible chemical equilibration of the chemical boundary layer with the overlying mantle. Methodologically, we will perform large-scale molecular dynamics simulation using both density functional theory and machine learning potentials, and – based on molecular dynamics simulations – compute thermodynamic potentials of candidate reaction products to quantitatively determine partitioning of light elements between liquid iron-alloys (the core) and solid (the mantle) and liquid silicates (the magma ocean) at relevant high pressures and temperatures.

核幔边界以下可能存在停滞层，这给地球深部提出了许多重要的地球物理和地球化学问题。在拟议的项目中，我们计划探索这一层由不同的化学成分造成的可能性，即，轻元素在那里的积累，最初在核心偏析期间在较高温度下被带到核心。为此，我们将进行从头计算模拟的不同方面，可能会导致这样的轻元素富集层的形成和稳定性，并确定动态重要的物理性质it.For的地球发电机和热演化的考虑，在重点计划内提出的其他项目，密度，粘度和热导率的意义。我们已经同意与另外两个项目合作，Wicht和Zhu的地球发电机，Tosi等人的热演化模拟。作为地球发电机的额外驱动力，特别是在年轻的地球中，我们将探索SiO2从初始内核成分中可能的出溶。在一个更地球化学的背景下，我们将考虑轻元素的运输，在其形成过程中，通过岩浆海洋和金属之间的平衡，以及可能的化学边界层与上覆地幔的化学平衡。在方法上，我们将使用密度泛函理论和机器学习势进行大规模分子动力学模拟，并基于分子动力学模拟计算候选反应产物的热力学势，以定量确定轻元素在相关高压和高温下在液态铁合金（核心）和固态（地幔）以及液态硅酸盐（岩浆海洋）之间的分配。