地球内核顶部结构的“半球"变化分界面性质

地球内核的形成促进了地磁场的产生以及核幔物质和能量的交换。内核顶部的结构因保留了内核形成过程的痕迹，一直是近年来地球深部动力学和核幔演化过程研究的重要内容和前沿热点。地震学研究表明，内核顶部具一阶的“半球”特征，即内核的东西半球结构不同，但这种半球结构的形成机制因研究不够全面尚存在争议。为此，本项目以内核半球结构的分界界面为主要研究对象，拟通过波形拟合、层析成像等方法具体研究分界界面的位置、尖锐度和深度分布特征，以及分界界面周围的内核顶部各向异性和不均匀性分布特征，以期对半球结构的形成机制有进一步的认识。项目研究成果将可以验证现有内核形成机制的有效性，探讨约束内核形成过程可能需要的其它因素，并为研究地核的物质组成和核幔作用提供重要信息。

Duringthe formation of the Earth’s inner core, latent heat and light elements are released, which drive the convection of the outer core and generate the Earth’s magnetic field. The structure in the top inner core is linked closely to this formation process, and thus provide essential information for our understanding of dynamic evolution of the inner core and outer core convection. Seismological studies have shown that one of the most prominent characteristics in the top inner core is its hemispherical structure, which shows different structures in the eastern and western hemisphere. However, the mechanisms for generating this structure still remain unclear, and they are incapable of explaining the anisotropy in the top inner core as well. Here in this proposal, we focus on the boundary characteristics between the two hemispheres of the inner core, as well as the anisotropy and heterogeneity structures in its surrounding areas. Using waveform modeling and tomography inversion, the location, sharpness, and the depth extent of the boundary will be investigated. Meanwhile, local structures in the surrounding area will also be imaged. Our results will provide new constraints on the dynamic process of the core, help understanding the chemical composition and the core mantle interaction.