碎屑岩地层中逆断层内部结构演化模式及封闭性

The evolution model and sealing of reverse fault in clastic strata

为了建立碎屑岩地层中逆断层的演化模式,在对柴达木盆地西缘地表出露断层的系统观察与实验分析基础上,从宏观与微观2个方面研究断层的演化过程,分析不同规模断裂带内部结构以及侧向封闭能力。研究结果表明:断裂带形成演化主要经历3个阶段:(1)断层断距较小时,断层为"一元"型结构,由破碎带与滑动面构成;(2)断层断距中等时,断层为典型的"二元"型结构,具有断层核与破碎带,断层核内部被断层泥和断层角砾岩渐变充填;(3)断层断距较大时,断层核内部仅充填断层泥。当达到一定断距条件时,形成断层核以断层泥充填为主,断层开始具有一定封闭能力,断层断距越大,断层核内部泥质含量越高,断层所具有的侧向封闭能力越强。

In order to establish the reverse fault evolution model in clastic strata,on the basis of systematic observation and experimental analysis of the fault on the western margin of Qaidam Basin,combined with the research of the evolution of fault from both macroscopic and microscopic aspects, the internal structure and lateral sealing ability of different scale fault zones were analyzed.The results show that the evolution of fault zone has three stages：（1） When fault throw is minor,the fault is the ＂one factor＂ structure,it con- sists of damage zone and slipping surface; （2） When fault throw is moderate,the fault is the ＂two-factor＂ structure,it consists of damage zone and fault core,the fault core is filled with fault gouge and fault brecci- a; （3） When fault throw is large,the fault core is filled with fault gouge only.When a certain fault throw is reached,the fault begins to have certain sealing ability,the larger the fault scale （throw）,the greater the content of the fault gouge,the higher SGR,the greater the lateral sealing ability of the fault.