增厚大陆岩石层热边界层对流剥离的数值模拟

用数值模拟方法模拟了增厚大陆岩石层热边界层被对流地幔剥离并为软流层物质替代的动力学过程．结果表明，在初始温度分层分布、侧向均匀但存在微小热扰动的流场中，80km厚的增厚岩石层热边界层约需60Ma才能被完全剥离，剥离的速率微弱地依赖扰动的强度；在已建立好的流场中，同样厚度的增厚热边界层只需约10Ma就可被剥离．模拟结果暗示青藏高原地壳及岩石层在岩石层增厚和剥离以前就很热，其下伏地馒中可能已存在建立好的上地幔小尺度对流系统，而该尺度的对流系统很可能是由特提斯海洋岩石圈俯冲和消减诱发的

NUMERICAL SIMULATION OF THE CONVECTIVE REMOVAL OF THE THICKENED THERMAL BOUNDARY LAYER OF CONTINENTAL LOTHOSPHERE

The dynamic process of the convective removal of the thickened thermal boundary layer of continental lithosphere by mantle and its replacement by asthenosphere is investigated by the method of numerical simulation in this paper. The numerical result shows that in the initial flow field, where lateral temperature is homogeneous and slightly perturbed, the thickened thermal boundsry layer with the thickness of 80kin can be removed completely in 60 Ma. The removal rate is slightly dependent upon the amplitude of perturbation. In the well established flow field, the thickened thermal boundary layer with the same thickness can be removed in about 10Ma. This result suggests that the crust and lithosphere was very hot before the thickening and removal of the lithoophere. There aught exist the small-scale convection in the upper mantle, which may be induced by the underthrust and subduction of Tethys oceanic lithosphere..