扩散对地球体系中不同尺度的化学交换和质量传输发挥了关键作用。橄榄石作为上地幔最主要矿物，而铁和镁是地球上元素丰度最高的两种元素之一，因此橄榄石中铁和镁的扩散行为将在很大程度上影响一系列地幔动力学过程的时间和空间尺度。由于水能够极大地影响地幔矿物的物理化学性质，显然用地幔矿物在不含水条件下获得的扩散系数来推断真实地球内部环境就可能存在较大偏差。因此，定量研究水对橄榄石中Fe-Mg互扩散系数的影响将有助于正确认识水在地球内部各种动力学过程中所起的关键作用。. 本项目将以单晶和多晶橄榄石为研究对象，拟同时在高温高压和不同氧逸度条件下系统研究水对单晶和多晶橄榄石中Fe-Mg互扩散系数的影响，探索并建立橄榄石的Fe-Mg互扩散系数随水含量、温度、压力、成分、氧逸度等因素的变化规律，揭示水对扩散机制影响的微观机理，从而有望对上地幔中的一些关键地球动力学过程提供科学依据和重要约束。

Diffusion plays a key role in chemical exchange and mass transfer at different scales in the Earth system. Olivine is the most important mineral in the upper mantle, and iron and magnesium are two of the most abundant elements on the Earth. Therefore, the diffusion behavior of iron and magnesium in olivine will significantly affect the temporal and spatial scales of a series of mantle dynamics processes. Because water can greatly affect the physical and chemical properties of mantle minerals, it is obvious that there may be a large deviation or even misunderstanding in deducing the real Earth interior from the diffusion coefficients of mantle minerals obtained under anhydrous conditions. Therefore, the quantitative study of the effect of water on the Fe–Mg interdiffusion coefficient (DFe-Mg) in olivine will help to correctly understand the key role of water in various dynamic processes within the Earth.. In this project, single crystal and polycrystalline olivine will be taken as the research object, we will systematically investigate the effect of water on DFe-Mg in olivine under high-temperature and high-pressure and different oxygen fugacity conditions. We will try to explore and establish the constitutive relationships among DFe-Mg and water content, temperature, pressure, composition, oxygen fugacity and other factors, and reveal the micro physical mechanism of water influencing Fe–Mg interdiffusion in olivine in detail. After this project being finished, it is expected to provide scientific basis and important constraints for some key geodynamic processes in the upper mantle.