断层泥伊利石物理化学特征及其意义

Characteristics of Illite Minerals in Fault Gouge and Their Geological Implications

通过X射线衍射和化学分析等方法,研究了云南水电站断层泥中伊利石物理化学特征,结果显示:1伊利石物质的X射线衍射特征为Δ[(002)-(001)]>8,Ir>1,BB1<4°,属I+ISII有序混层,膨胀层小于15%,晶胞参数b0=8.991,1M多型结构;2K2O的平均含量9.1%变化范围在8.5%-10%之间;3K2O和Fe2O3含量之间为负相关,K2O含量与Δ[(002)-(001)]2θ值呈正相关,而K2O与Ir值呈负相关。上述特征表明该断层泥伊利石是在低温(小于200℃)低压环境下生成。它的形成与断层稳定滑动机制有关。由此推测该断层未来发生大地震的可能性较小。

The characteristics of minerals,such as illite,etc.in fault gouge from Xiaowan Fault are studied with X-ray diffraction and chemical analysis.The results show that：（1） X-ray diffraction features of illite are ⊿ [（002）-（001）] ＞8°,I,＞1,BB1 ＜4°,belonging to orderly mixed layer.Expansive layer accounts are smaller than 15％.The crystal cell parameters b0=8.991 （A）,1M polytype structure.（2） KO2 content varies from 4.18％ to 5.56％.（3） There is negative correlation exists between K2O and Fe2O3.There is a positive correlation between ⊿ [（002）-（001）] and K2O,but negative correlation exists between K2O and Ir.All of characteristics suggest that illite was formed in the environment with low-temperature and low-pressure,which is related with the low level of fault activity and low probability of strong earthquake occurrence in future.