板块绝对运动及地幔热对流

本文以板块绝对运动AM1-2模型为边界条件探讨了不同的瑞利数下地幔热对流模型.结果表明,瑞利数小于10000（529.41）时,地幔对流呈现以板块驱动图式,运动的极型场和环型场由板块运动激发,两种场占有差不多相同的功率.当瑞利数增加到接近或略超过最低临界值时（约1.5倍）,对流呈现出复杂状态:1.板块运动速率小于下伏地幔对流速率;2.区域性的双层对流环出现;3.对流谱成分发生变化;4.环型场仅在地幔很浅的区域中起作用,而在地幔深部对流图式中影响很小.

PLATE ABSOLUTE MOTIONS AND THERMAL MANTLE CONVECTION

Several thermal convection madels in the mantle with a moving upper boundary expressed "by plate absolute motion model AMI-2 and different thermodynamical parameters are investigated in this paper. Results show that fhe mantle flow is driven by the plate motions when the Rayleigh number of the mantle is less than 10000（529.41） and two components of plate motions （poloidal and toroidal） almost have same power. With the increasing of Rayleigh number the convection patterns apear more complicated: 1. the rate of plate motions is smaller than the rate of under laying mantle flow, 2. two layers convections apear in some regions. 3. the spectum of mantle flow is changeable, 4. the weight of toroidal componet in the mantle flow becomes smaller.