上地幔密度异常驱动小尺度对流及实验模型

建立了由密度异常驱动上地幔小尺度对流的数学 物理模型， 发展了利用地震层析成像数据反演上地幔小尺度对流的基本理论和方法. 该模型建立在三维直角坐标系框架上， 假设地震层析成像所显示的地震波速度异常对应于上地幔物质密度异常， 而该密度异常反映了上地幔小尺度热对流系统的温度异常场. 模型首先将地震层析成像确定的地震波速度异常转换为密度异常， 并视其为对流的驱动力； 进而利用三维傅立叶变换， 在波数域内， 在给定的边界条件下， 求解控制流体行为的运动方程和连续性方程， 最后求得对流的流场. 为检验本研究提出的理论和方法的有效性， 本文使用了两个简单的实验模型: 热体和冷体模型； 俯冲断离( break off)板片模型， 计算了其驱动的地幔流场. 结果表明， 本文提供的理论和方法， 可以直接应用于与区域岩石层构造动力学相关的上地幔小尺度对流的研究. 

UPPER MANTLE CONVECTION DRIVING BY DENSITY ANOMALY AND A TEST MODEL

A mathematic physical convection model in upper mantle is established in this paper. This model is in a three dimensional frame. Assume that the density anomalies, which are mapped from the seismic tomography data, are responding to the temperature perturbation in the connective system. This model takes the density anomalies as the driving force for the mantle convection. We solve the basic equations with different boundary conditions in a domination of wave number by using the FFT arithmetic. In order to test the validity of our theory and method two simple models (higher lower density body and break off slab) are employed to calculate their flow patters in this paper. Results show that our method can be directly used to investigate the upper mantle convection patterns and its related problems of lithospheric dynamics.