3D Numerical Modeling of Subduction Zone Anisotropy

9814242在太平洋俯冲带附近的Malin剪切波分裂观测表明，在俯冲带内和俯冲带之间，弧后的平均橄榄石a轴取向是变化的，而在向海侧地幔板块下的橄榄石a轴取向主要平行于海沟。该项目提出利用三维数值模型研究非平面板块的同时下倾和回滚运动以及上覆板块的运动对俯冲板块附近上地幔流动和各向异性的影响。同时的板块运动、板块几何和上覆板块运动学对地幔流动和各向异性的影响需要比目前所做的更详细的研究。三维数值模型将产生的结果可以与当前的剪切波分裂观测结果进行比较。

9814242 Malin Shear-wave splitting observations in the vicinity of subduction zones of the Pacific indicate that average olivine a-axis orientations beneath back-arcs are variable within and between subduction zones, and those beneath slabs in the seaward-side mantle are predominantly parallel to the trenches. The PI proposes to use a 3-D numerical model to study the effects of simultaneous down-dip and rollback motion of a non-planar plate, and the motion of an overriding plate on upper mantle flow and anisotropy in the vicinity of a subducting slab. The influence of simultaneous slab motion, plate geometry and overriding plate kinematics on mantle flow and anisotropy needs to be examined in more detail than has presently been done. The 3-D numerical model will produce results that can be compared to current shear-wave splitting observations.