拉张环境下构造层次的划分

Dividing Tectonic Levels of Extensional Deformation Region

构造层次的概念最初是针对挤压变形区提出来的。研究表明,这一概念也可用于拉张变形区,但其特征及应变机制与挤压变形区有显著不同。拉张变形区的构造层次也可分为浅层次、中层次和深层次,各层次构造形成的最大主压应力方向为垂直方向。浅层次应变机制为剪切作用,形成铲形正断层及其相伴生的滚动背斜、反向断层等;中层次应变机制为横弯引起的弯滑作用;形成等厚褶皱、滑脱构造等;深层次的主导应变机制为上部弯流作用、下部流动作用,以形成顶薄褶皱和流动褶皱为特征。不同构造环境的各种构造层次叠加在一起,常形成复杂的构造图案。

The concept of tectonic level was initially put forward to describe the region of compressional deformation. The research shows that tectonic level may also be applied to the region of extensional deformation. The tectonic levels of extensional deformational region may be divided into 3 types:top.middle, and deep levels. There is presented in this paper the deformational feature,mechanisms, and main stress orientation of each level in the region of extensional deformation. A comparison is also made between the tectonic levels under the compressional setting and those under the extensional setting. A brief discussion of the superposition of tectonic levels is provided in this paper.