论文部分内容阅读
在青藏高原中部的温泉盆地西侧发育了1条倾向东的强烈活动的近SN正断层——温泉盆地西缘断裂。它是在印度板块与欧亚板块强烈碰撞的背景下,青藏高原中北部地区自晚新生代以来发生近EW向伸展变形的产物。晚新生代以来,该断裂上的最大垂直错动量不会<21km,错动中生代褶皱地层所暗示的最大垂直位移量为(60±22)km。第四纪期间,该断裂发生了多期活动,形成了山前的多套断层三角面和多级断层陡坎地貌。根据断裂垂直错动晚第四纪期间不同时代的地层和地貌体所形成的断层崖高度估算,其晚第四纪以来的最大活动速率不超过12mm/a,平均活动速率为045mm/a。初步的探槽分析表明,晚更新世末期以来沿该断裂至少发生了3次震级不同的古地震事件。综合该断裂的全新世活动特点推断,它是在未来具有较大可能发生6～7级地震的一条重要控震断裂。
On the west side of the hot spring basin in the central part of the Qinghai-Xizang Plateau, a strong active near-SN normal fault-western margin of the hot spring basin is developed. It is a product of near-EW extensional deformation in the central-northern Qinghai-Tibet Plateau since late-Cenozoic under the background of strong collision between Indian plate and Eurasian plate. Since the Late Cenozoic, the maximum vertical displacement of this fault is less than 21 km. The maximum vertical displacement implied by the migrating Mesozoic fold strata is (60 ± 22) km. Quaternary period, the fault occurred a number of activities, forming a set of front of the mountain sets of multi-faceted fault triangular and multistage fault ridge morphology. According to the estimation of the height of fault cliffs formed by strata and geomorphic bodies of different ages during the Late Quaternary of the fault, the maximum activity rate of late Quaternary does not exceed 12mm / a and the average activity rate is 045mm / a. Preliminary trench analysis shows that at least three paleo-seismic events of this magnitude have occurred along the fault since the late Pleistocene. Based on the characteristics of the Holocene activity of the fault, it is inferred that it is an important earthquake-controlled fault with a large magnitude of 6-7 earthquakes in the future.