晚更新世以来黄土塬区临潼-长安断裂的活动性研究

ACTIVITY OF THE LINTONG-CHANG'AN FAULT IN LOESS TABLELANDS SINCE LATE PLEISTOCENE

黄土塬区晚更新世风成黄土分布广、特征明显,与断裂关系直接。通过小鲍陂、桥沟、冢底村3个典型晚更新世断层剖面的仔细观察、测量和年代学工作,获得了白鹿塬、少陵塬、横岭塬3个黄土台塬上临潼-长安断裂晚更新世以来的活动性参数和区域地层的年代序列。研究结果表明,晚更新世以来临潼-长安断裂在白鹿塬段活动性最强,明显错断了黄土L1-2地层,而其两侧的少陵塬和横岭塬上,同时期断裂的活动性相对弱些。剖面中黄土L1-2及其以上地层被裂缝穿切的现象有可能说明,晚更新世中晚期以来临潼-长安断裂仍在活动,仅是强度有所减弱。

The late Pleistocene aeolian loess distributes widely in the loess tableland area. It has obvious features and is directly related with faulting. By the observation, measurement and dating to three typical sections at Xiaobaopo, Qiaogou and Zhongdicun, this paper obtained the activity parameters of the Lintong-Chang＇an Fault since the late Pleistocene and the age stratigraphic sequence of the tablelands of Bailuyuan,Shaolingyuan and Henglingyuan. Research results show that the Bailuyuan tableland has experienced the strongest faulting since late Pleistocene, which offset the loess strata L1-2. On the Shaolingyuan and Henglingyuan tablelands, the activity of Lintong-Chang＇an Fault is weak in the same period. The phenomenon of the fissures incising L1-2 and their upper strata shows that the Lintong-Chang＇an Fault is still active since late Pleistocene, but its activity seems weak.