软流层静压推力及其板块动力学意义

地幔软流层之上漂浮着地球板块,软流层对板块存在流体静压——软流层静压推力。对海洋板块而言,软流层静压推力在物理意义上与传统的分布力型洋脊推力没有差别。假定板块内部的应力场在水平和竖直方向上互相解耦,可利用二维球壳有限单元模型计算板内应力场的水平分量,并根据重力均衡理论计算其竖直分量,进而计算其差分应力场。利用软流层静压推力的概念,在研究有关的板块动力学问题时,能够充分利用观测资料中的应力状态信息作为约束条件,简明有效地解释部分海洋与大陆过渡区域及重力非均衡区域的复杂应力场图象。

ASTHENOSPHERIC STATIC PUSH AND ITS IMPLICATIONS TO PLATE DYNAMICS

Lithospheric plates are exerted by a fluid pressure,since they immediately overlie the asthenosphere. We define this fluid pressure as Asthenospheric Static Push (ASP). For a oceanic plate,there is no difference of ASP and the traditional ridge push force. Assuming a decoupling of horizontal components and vertical component of the intraplate stresses,we have the two horizontal components of the intraplate stresses due to the ASP and other forces using the 2-D spherical finite element modeling,and the vertical component by isostasy. A differential stress field is obtained by subtracting the vertical component of stresses from the horizontal components.
By introducing the concept of ASP,it is convenient to use the observed stress regimes as constraints to study the problems of plate dynamics and to explain the observed complex stress patterns in the transition regions between the sea and the continent and those in the anomalous gravity regions.