下地幔底部D"层的热-化学-相结构的三维动力学数值模拟

The D" layer above the core-mantle boundary (CMB) has a complex structure over a broad range of spatial scales, which controls the rate, spatial and temporal distribution of the heat transport across the CMB. This proposal aims to build up time-dependent three-dimensional (3-D) mantle convection numerical models with non-Newtonian rheology, solid-state phase transitions, and complex composition as well as imposed plate motion back to 458 Ma.The numerical calculation results for temperature, composition and PPV phase will be used to synthesize seismic shear wave velocity anomalies. With constraints from seismic tomography, geochemistry and rock physics, a best fitting model would be established to simulate the realistic Earth's mantle flow and reconstruct the complex thermal-chemical-phase structures of the D" region. The results of this study will improve our understanding of dynamics in the D" region and the mechanisms of heat transport across the CMB. In addition, this study will yield a better estimate of the magnitude of CMB heat flux, as well as its spatial and temporal variation.

下地幔底部的D"层内结构复杂，多种动力学过程相互叠加，控制着核幔边界热通量的传输速率、空间分布和时间变化。本项目拟建立一个包含粘度变化、多组分、相变特征的三维全地幔对流数值模型，并考虑458 Ma以来的板块运动的驱动作用。我们将把动力学模拟得到的温度、化学组成和相组成等数据转变为合成地震数据，综合使用地震层析成像数据、地球化学数据和岩石物理数据作为严格的约束条件，建立最佳的数值模型来模拟真实地球的地幔流体运动，重构D"层复杂结构的形成过程。研究成果将揭示下地幔底层D"区域的热-化学-相结构的动力学机制和地球核幔边界热流的传输机制，促进对核幔边界热流分布和结构的了解。

下地幔底部的D"层内结构复杂，多种动力学过程相互叠加，控制着核幔边界热通量的传输速率、空间分布和时间变化。本项目建立了包含复杂参数的三维地幔对流数值模型，探讨了加热模式、板块运动、粘度变化、相变和 D"层化学组成等因素对下地幔结构的影响，最大限度地近似模拟地球的真实条件。我们进行了数十组参数组合的计算实验。使用地震层析成像数据、地球化学数据和岩石物理数据作为约束条件，我们得到了一个优选模型，模拟了地球核幔边界附近的地幔区域的动力学过程，研究了热-化学-相变的相互叠加的作用，及其对地球核幔边界热结构的影响。