西藏日喀则拉堆—乃东断裂带断层泥石英微形貌特征及其年代学意义

Surface Texture Characteristics and Dating Implication of the Gouge Quartz in the Ladui-Naidong Faults,Xigaze,Tibet

为推断西藏日喀则拉堆—乃东断裂带(LNF)的断层活动年代及活动性,在野外调查的基础上,对该断裂带上采集的2件断层泥样品中的石英进行了扫描电镜(SEM)下微形貌观察,并将石英表面形貌出现频率绘制成统计直方图。结果显示,拉堆—乃东断裂带第四纪以来具有明显的活动性;且石英微形貌大量出现贝壳状结构、次贝壳状结构和桔皮状结构的组合类型,推断该断裂带自中更新世进入活动高峰期,全新世以来仍在活动。

In order to determine the chronology and the activity of the Ladui-Naidong Faults（LNF） at Xigaze,Tibet,we examined quartz samples of two fault gouge samples collected from the LNF fault. The quartz samples were carefully observed and counted under SEM and the statistic histograms were made according to the occurrence frequency of the surface micro-morphologies. The results showed that the LNF had obvious activities since the Quaternary and the micro-morphology of the quartz showed lots of texture combinations of conchoidal texture,subconchoidal texture and orange peel texture,indicating that the LNF reached its peak period of activity in the middle Pleistocene and is still active in the Holocene.