祁连山北缘断裂带第四纪运动特征的初步研究
PRELIMINARY STUDY OF THE QUATERNARY FAULTING ON THE QILIAN MOUNTAIN NORTHERN MARGINAL FAULT ZONE
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摘要: 调查表明,自第四纪以来,祁连山北缘断裂带仍处在北(偏东)向挤压作用下,总体上以左旋逆推运动为主。Q1与Q2及Q2与Q3之间是区内两期重要构造活动期。实测资料表明,晚第四纪以来,该断裂的平均地质位错速率为5毫米/年,西段,垂直位错为主,年位错率约2毫米/年,东段,水平位错为主,速率为≥5毫米/年。Abstract: The NEN-SWS conpressive stress field in the Qilian mountain region is understood basing on the surveys of the crustal deformation and the faulting in the Quaternary period. Since lata Quaternary, the Qilian mountain marginal fault zone exhibited transcureut thrusing with left lateral slip. The geological and georaorphic surveys show that the npfolding and upthrusting are piominent in the period between Q1 and Q2 and between Q2 and Q3, the plastic flow of the upper crust material and lateral displasement of the fault are piincipal. In this time, the eastern segment of the fault (e. g. Mao Mao mountain fault) reactivated as a left lateral shear zone in right-step pattern. The results of the investigation indicate that the average slip rate of the fault is 2-5 mm/y. But in the western segment of the fault, vertical displacement is principal (2 mm/y.), and at it's eastern segment, there is the prominent horizontal displacement (≥5 mm/y.). Basing on the data revealed by the trenching and the computation of the average seismic slip rate, we know that the recurrence intervals of M≥7 earthquakes in the seismic area is 2000~4000 years.
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[1] 王荃、刘雪亚,我国西部祁连山区的古海洋地売及其大地构造意义,地质科学,1,1976. [2] 李春昱等,秦岭及祁连山构造发育史,国际交流地质学术论文集(1),地质出版社,1978. [3] 魏春海等,中国祁连山地质构造的基本特征,地质学报,2,1978. [4] 崔中元等,甘肃龙首山地区活动构造特征,西北地震学报,1,1983. [5] 余伯良,甘肃走廊新构造运动的特征与意义,中国科学院第一次新构造运动座谈会发言记录,科学出版社,1957. [6] 殷永候,甘肃河西龙廊(永昌至玉门)第四纪地质问题,中国第四纪研究,2,2,1939. [7] 方鸿慈,关于河西走廊第四纪地质问超的几点意见,地质论评,22,6,1964. [8] 向宏发、虢顺民,河西走廊玉门-嘉峪关地区活动断裂的初步认识,现代地壳运动研究(5),地震出版社,1988. [9] 马杏垣等,中国的活动块体运动与构造变形,现代地壳运动研究(3),地震山版社,1987. [10] 邓起东等,海原断裂带和1920年海原地震断层的基本特征及其形成机制,现代地壳运动研究(3),地震出版社.1987. [11] 虢顺民等,云南红河断裂带北段断裂位错与地震重复发生的时间间隔,地震地质,1期,1984. [12] 向宏发、方仲景等,三河-平谷8级地震区的构造背景与大震重复性研究,地震地质,1,1988. [13] Sharma, K. K, Crustal growth and two-stage India-Eurasia collision in Ladakh, Tectonophysics 134, P17-28. 1987. [14] M. M. Saikia, Kotoky, P. and Duarah. R. A zone of plate convergence with associated seismic activity-The Indo-Burman arc. Tectonophysics, 134. 145, 1987. -

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