准噶尔盆地南缘霍尔果斯和吐谷鲁断裂带断层泥分形特征与断裂活动关系

Correlation between the fractal dimension of fault gouges and fault activity in the Huoerguosi and Tugulu faults zones along southern edge of Junggar basin

根据采集的天然断层泥样品 ,对准噶尔盆地南缘霍尔果斯和吐谷鲁逆断裂带中断层泥进行了显微构造、显微形貌和分形研究。研究结果表明 ,断层泥至少存在三期变形 ;同时断层泥和石英碎粒中既发育有线状擦痕、阶步等典型的粘滑活动显微构造 ,也发育有剪切滑动、定向排列等典型的蠕滑活动变形现象 ,说明了断裂活动的长期性和复杂性。断层泥的分形研究表明 ,霍尔果斯和吐谷鲁断裂带断层泥分维值分别在 2 .17～ 2 .6 3和 2 .76～ 2 .89变化 ,分维值与断层运动方式粘滑或蠕滑不存在因果关系。因此 ,断层泥分维值能否作为判别断裂活动方式值得进一步研究。

The grain size distribution,microscopic shape and microstructure characters of fault gouge in the Huoerguosi and Tugulu reverse fault zones along the southern edge of Junggar basin are studied from the collected samples of natural fault gouge. The results show that the gouges underwent three deformation stages, many stick-slip structural marks such as slickenside striations and steps appear in gouges and on quartz grains, and many creeping structural marks such as shear-slip and directional arrangement of clay minerals also exist, which imply the fault activity with multistage and complicated mechanism. The fractal dimensions of fault gouges range from 2.17 to 2.63 and from 2.76 to 2.89 for Huoerguosi and Tugulu fault zone, respectively, which indicates that the fractal dimensions of fault gouges do not correlate to fault activity—sticky slip or steady creeping slip. Therefore, a research on that whether the fractal dimensions of fault gouges can be a judgement on fault slip mode is needed.