断层视活动与真实活动的探讨

Approach to apparent and true fault activity

占王忠,许浚远

Zhan Wangzhong Xu Junyuan

中国地质大学资源学院，湖北 武汉 430074

Faculty of Resources, China University of Geoscience, Wuhan 430074, China

描述生长断层的主要活动参数（生长指数、古落差、活动速率等）都没有考虑断层上下盘地层的压实作用对断层活动性造成的影响，通过统计的这些活动参数描述断层只能认为是对断层“视活动”的描述，对于断层真实活动的描述必须将压实作用考虑进去。文中以活动速率为例，对计算生长断层活动速率方法进行校正，得出正确计算活动速率方法的公式。当研究断层为正断层时，按照传统方法得到的断层“视活动”速率将小于断层真实活动速率；研究断层为逆断层时，“视活动”活动速率将大于断层真实活动速率。探讨生长断层真实活动参数时，必须剔除压实作用对断层活动参数的干扰，从而对断层真实活动性以及演化历史有更清晰的探讨。

Effects of sedimentary overburden compaction are not considered in traditional quantitative description of activities of faults using such parameters as growth index, paleo-fall and activity ratio. In fact, these effects must be taken into account. This paper takes calculation of growth fault activity ratio for example to explain how to consider the effects. A correct formula  is proposed for calculation of growth fault activity ratio. When the studied fault is a normal fault, traditional "apparent fault activity ratio" is less than  its real one and  when it is a reverse fault, the traditional "apparent fault activity ratio" is larger than its real one . Only when sedimentary compaction is considered can meaningful quantitative study of fault activity in sedimentary basins and evolution be made.