【摘要】 <正> 华北平原早第三纪的主导构造是伸展断裂。伸展断裂的主要特征是水平拉伸及其导致的地层或地块的旋转。旋转引起地块掀斜,掀斜是直观的拉伸构造。涉及基底的断裂,其伸展最终造成地壳减薄。这种构造不仅是华北平原,也是鄂尔多斯地块周边新生代断陷的主要构造;在大陆裂谷区、美国西部的盆岭构造及大西洋的被动边缘普遍发育。更多还原

【Abstract】 The principal tectonis are extensional faults in Eogene in the North China plain and the principal faults are listric nomal faults. Due to extension, the secondary Ho-mothetic faults or Antithetic faults are developed at the hanging walls of listric nomal faults. Under continuous extension, subseeondary faults are developed at the hanging walls of Secondary faults. Such secondary faults are usually formmec in clustering. The more secondary, the faults are, the later the formation of faults would be, the higher, the dip angle’ of faults, the straighter, the fault planes, the more equal, the distances between them. Such features are useful to distinguish the recency and activity of faults.更多还原