六盘山东麓断裂断层泥的组构特征及其意义

THE FABRIC OF FAULT GOUGE FROM THE EASTERN LIUPANSHAN PIEDMONT FAULT ZONE AND THEIR IMPLICATION

本文采用宏观与微观相结合的方法 ,研究六盘山东麓断裂的滑动方式。结果表明 :(1)根据断层泥组构特征 ,六盘山东麓断裂可划分为北、中、南 3段 ,这与前人宏观分段结果相一致 ;(2 )北段断层泥局部强烈变形 ,发育牵引褶皱 ,吕德剪切角 (R1)介于 11°～ 2 6° ,以及伊利石无明显的优选方位组构 ,表明该段断层活动是以粘滑为主的左旋走滑运动 ;(3)中、南段断层泥普遍变形 ,吕德剪切角 (R1)一般小于 11° ,P叶理、带状褶皱和肠状构造发育 ,以及伊利石复杂的优选方位组构 ,显示该断层的活动是以蠕滑为主的多期逆冲滑动。

The mode of slipping along the eastern Liupanshan piedmont fault zone is analyzed through both macroscopic and microscopic investigations. The results show that (1)this fault zone can be divided into north,middle and south three segments based on the characteristics of the fabric from fault gouge. This is consistent with the result from macroscopic along the fault zone in recent years.(2)local strong deformation, traction fold, Riedel shears angle ( R 1) being in the range of 11°～26°, P foliation and randomly preferred orientation of illite mineral that developed within the fault gouge are indication of stick slip and left lateral strike-slip along the north segment.(3)general deformation, Riedel shears being at angle of 11°or less, banded foled, ptygmatic structure and polygemic preferred orientation of illite mineral that developed within the fault gouges are the indicators of creep slip and reverse slip along the middle and south segments.