青海热水-日月山断裂带的新活动特征  

CHARACTERISTICS OF THE MODERN ACTIVITY OF THE RESHUI-RIYUESHAN FAULT ZONE IN QINGHAI PROVINCE

作　　者：袁道阳[1] 刘小龙[1] 张培震[2] 刘百篪[1] 

机构地区：[1]中国地震局兰州地震研究所,兰州730000 [2]中国地震局地质研究所,北京100029

出　　处：《地震地质》2003年第1期155-165,共11页Seismology and Geology

基　　金：国家重点基础研究发展规划项目 (G19980 4 0 70 1);国家杰出青年基金 ( 4 982 5 10 4 );地震科学联合基金 ( 10 2 0 5 5 )资助。

摘　　要：热水 -日月山断裂带是发育在青藏高原东北缘柴达木 -祁连活动地块内部的 1条重要的NNW向逆 -右旋走滑活动断裂带 ,长约 183km。断裂由 4条不连续的次级断裂段右阶羽列而成 ,阶距 2～ 3km左右 ,在不连续部位形成拉分区。主断裂两端则形成帚状分叉。断裂活动形成了一系列山脊、冲沟和阶地等右旋断错微地貌 ,其中Ⅰ级阶地右旋断错约 8～ 11m ,Ⅱ级阶地右旋断错约 35m。同时沿断裂带还形成了许多断层陡坎 ,Ⅰ级阶地或洪积台地上断层陡坎高约 0 .5～ 1m ,最高达 2 .8m ,Ⅱ级阶地或台地上的断层陡坎高约 2 .5～ 3m ,最高达 4～ 5m。根据相应的阶地年代 ,计算得到断裂带全新世以来的平均水平滑动速率为 3 16mm/a ,垂直滑动速率为 0 .83mm/a。The Reshui-Riyueshan active fault zone lies within the central part of the Qaidam-Qilianshan active block on the northeastern margin of the Qinghai-Tibet Plateau. It is a NNW-trending right-lateral strike-slip active fault zone with reverse components characterized by clear linear features and strong activities. It initiates to the north of Datong River, and extends southward through the Reshui coal mine, running along the eastern side of the NNW-oriented Datongshan and Riyueshan upheaval area, and obliquely connected with Lajishan active fault zone at the pass of Riyueshan Mountain. The fault zone is generally striking N35°W, having a total length of about 183km and a relatively simple geometrical structure. It consists of 4 discontinuous secondary en echelon faults, which are Datong River (F 1-1), Reshui (F 1-2), Haiyan (F 1-3) and Riyueshan (F 1-4) Faults, respectively. Extensional zones or pull-apart small basins, such as Ketu basin, were formed at the step-over of these secondary faults. The wide of the step-over is about 2～3km. The Reshui-Riyueshan active fault zone was a compressive reverse fault zone in the early period, and caused the strong compressive deformation of late Cenozoic strata on both side of the fault. Since late Quaternary, the fault zone has become a right lateral strike-slip reverse fault, which has given rise to the formation of micro-morphology represented by right-laterally offset ridges, valleys and terraces. The larger offset may reach up to hundreds meters or more, while the smaller offsets are just about several meters. The right-lateral offset of the first level terrace is about 8～11m, while that of the second level terrace is about 35m. At the same time, there are many fault cliffs and fault scarps developed along the fault zone. The height of the fault scarp at the first level terrace is about 0.5～1m, and the highest one is about 2.8m; at the second level terrace and pluvial mesa, the height of the scarp is about 2.5～3m,with the highest value of about 4�

关 键 词：活动断裂 滑动速率 新活动 青海 

分 类 号：P315.2[天文地球—地震学]