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本文根据在地质上确实证明了的一种假定,即穹窿运动先于裂谷运动,提出了一种地壳上穹运动与地堑形成之间的关系的力学解释。裂谷运动和地堑形成可以在■.menez 楔形沉陷机制所产生的地壳引张条件下发生。楔形沉陷机制经修改被应用于大陆壳的最上部大致20km。如大致5km厚的充填于槽谷中的沉积物是由于这种机制形成的,则级将需要大致200kma(2千巴)的持续的引张。这样一种应力系统可以由于上升区地的地形负荷及其下的下伏低密度的上地幔区域所引起的上冲断层的联合效应产生。如地壳上部10-20km 是弹性的,而下伏区域又是可以由于粘一弹性蠕动而缓慢变形的,则200mPα的应力差可以由于这种过程产生于上部弹性地壳之中。经证明,正是这样一种应力系统,而不是由于上穹地壳的穹曲或由于板块边缘应力所产生的一种应力系统,才是地堑运动的首要原因。
This paper presents a mechanistic explanation of the relationship between the movement of the crustal dome and the formation of the graben, based on a hypothesis that is indeed geologically proven, namely that the dome was moved ahead of the rift. Rift movement and graben formation can occur under the crustal extension produced by the .menez wedge subsidence mechanism. Wedge sinking mechanism was modified to be applied to the uppermost part of the continental crust approximately 20 km. If a deposit of about 5 km thick filled in troughs is formed by this mechanism, the stage will require a sustained tension of approximately 200 kma (2 kPa). Such a stress system can result from the combined effect of upwelling faults caused by the topographic loading of the ascending region and the underlying low-lying upper mantle region. For example, 10-20km above the crust is elastic, and the underlying area is slowly deformable due to viscous-elastic creep. The stress difference of 200mPa can be generated by the process in the upper elastic crust. It is a stress system that has been proved to be the primary cause of grab movement, not because of a stress system created by the dome of the dome or by the edge of the plate.