日月山断裂德州段晚更新世以来的活动速率研究  

SLIP RATES OF THE RIYUE MT. FAULT AT DEZHOU SEGMENT SINCE LATE PLEISTOCENE

作　　者：李智敏[1] 苏鹏[2] 黄帅堂 田勤俭[4] 殷翔[1] LI Zhi-min;SU Peng;HUANG Shuai-tang;TIAN Qin-jian;YIN Xiang(Qinghai Earthquake Administration,Xining 810001,China;Key Laboratory of Active Tectonics and Volcano,Institute of Geology,China Earthquake Administration,Beijing 100029,China;Earthquake Administration of Xinjiang Uygur Autonomous Region,Urumqi 830011,China;Key Laboratory of Earthquake Prediction,Institute of Earthquake Science,China Earthquake Administration,Beijing 100036,China)

机构地区：[1]青海省地震局,西宁810001 [2]中国地震局地质研究所活动构造与火山重点实验室,北京100029 [3]新疆维吾尔自治区地震局,乌鲁木齐830011 [4]中国地震局地震预测研究所地震预测重点实验室,北京100036

出　　处：《地震地质》2018年第3期656-671,共16页Seismology and Geology

基　　金：青海省科技计划项目(2017-ZJ-775);中国地震局地震行业科研专项(201408023)共同资助

摘　　要：日月山断裂位于柴达木-祁连活动块体内部,受到东昆仑断裂和祁连-海原断裂等主边界断裂控制,形成了块体内部夹持于主边界断裂之间的次级构造。该断裂的构造位置特殊,确定其晚更新世以来的活动速率可提供青藏高原东北缘向外扩展的最新活动信息。文中通过建立地貌面时间标尺,分析断错的地貌标志,获得了以下2点认识:1)晚更新世以来,日月山断裂德州段主要发育一级洪积扇面fp,三级河流阶地面T1、T2和T3。其中洪积扇fp的废弃年龄约(21.2±0.6)ka,河流阶地T2的废弃年龄约(12.4±0.11)ka;2)日月山断裂晚更新世晚期以来的右旋走滑速率约(2.41±0.25)mm/a,全新世以来的右旋走滑速率约(2.18±0.40)mm/a,垂直滑动速率约(0.24±0.16)mm/a。日月山断裂德州段的右旋走滑速率在晚更新世晚期以来基本不变。日月山断裂并未切错大型块体的边界,而是青藏高原东北缘地区夹持于区域大型左旋走滑断裂内部的1套右旋走滑断裂中的1支。在青藏高原东北缘整体生长和扩展的过程中,右旋走滑断裂对各次级块体之间的变形协调起着十分重要的调节作用。The Riyue Mt. Fault is a secondary fault controlled by the major regional boundary faults（ East Kunlun Fault and Qilian-Haiyuan Fault）. It lies in the interior of Qaidam-Qilianshan block and between the major regional boundary faults. The Riyue Mt. fault zone locates in the special tectonic setting which can provide some evidences for recent activity of outward extension of NE Tibetan plateau,so it is of significance to determine the activity of Riyue Mt. Fault since late Pleistocene to Holocene. In this paper,we have obtained some findings along the Dezhou segment of Riyue Mt. Fault by interpreting the piedmont alluvial fans,measuring fault scarps,and excavating trenches across the fault scarp. The findings are as follows：（ 1） Since the late Pleistocene,there are an alluvial fan fpand three river terraces T1-T3 formed on the Dezhou segment. The abandonment age of fpis approximately（ 21. 2±0. 6） ka,and that of the river terrace T2 is（ 12. 4± 0. 11） ka.（ 2） Since the late Pleistocene,the dextral strike-slip rate of the Riyue Mt. Fault is（ 2. 41±0. 25） mm/a. In the Holocene,the dextral strike-slip rate of the fault is（ 2. 18±0. 40） mm/a,and its vertical displacement rate is（ 0. 24±0. 16）mm/a. This result indicates that the dextral strike-slip rate of the Riyue Mt. Fault has not changed since the late Pleistocene. It is believed that,as one of the dextral strike-slip faults,sandwiched between the the regional big left-lateral strike-slip faults,the Riyue Mt. Fault didn＇t cut the boundary zone of the large block. What＇s more,the dextral strike-slip faults play an important role in the coordination of deformation between the sub-blocks during the long term growth and expansion of the northeast Tibetan plateau.

关 键 词：日月山断裂 活动速率 德州段 地貌标尺 晚更新世 

分 类 号：P315.2[天文地球—地震学]