关于河西走廊盆地榆木山北缘断裂晚第四纪活动特征的新认识  

A new understanding of the characteristics of Late Quaternary activity of the northern Yumushan marginal fault in the Hexi corridor, northwestern China

作　　者：陈柏林[1] 王春宇[1] 宫红良[1] 刘建民[1] 张永双[1] 刘建生[2] 

机构地区：[1]中国地质科学院地质力学研究所,北京100081 [2]中国地震局兰州地震研究所,甘肃兰州730000

出　　处：《地质通报》2007年第8期976-983,共8页Geological Bulletin of China

基　　金：中国地质调查局地质调查项目(编号:水2003018-02和水2005018-04)资助。

摘　　要：榆木山北缘活动断裂属于河西走廊中段盆地内的次级隆起——榆木山隆起北侧断裂系的组成部分,它位于榆木山北缘断裂北侧山前,是与榆木山隆起有成生联系、活动时间很新的现代活动断裂。榆木山北缘活动断裂呈向北北东略微凸出的弧形,走向总体为北西向,倾向南西,自南东向北西走向由北西向渐变为北西西向,甚至近东西向,倾角自中等—低角度,东段较陡。榆木山北缘断裂的活动性质在剖面上表现为以南西盘向上逆冲为主,水平位移不明显,特别是中段的石炭口—窑儿沟口一带,在向南缓倾的主逆冲上盘往往发育反向逆冲断层,并导致上更新统砂砾层发生牵引褶皱。该断裂在距今13.1～13.3ka之间和距今3～5ka期间发生过2次明显的新构造活动。The northern Yumushan marginal active fault, as a component part of the faults system at the northern side of the Yumushan uplift-a second-order uplift m the central segment of the Hexi Corridor, is situated at the piedmont of the Yumushan Mountains and is a young, modern active fault genetically related to the Yumushan uplift. This active fault occurs as an arc convex slightly towards the NNE. It generally strikes NW and dips SW. From SE to NW, its strike changes gradually from NW to WNW and even to nearly E-W and its dip angle changes from medium to low, with the eastern segment dipping steeply. In section, the northern Yumushan marginal fault is manifested by thrusting of the southwestern block of the fault and indistinct horizontal displacement. It is particularly the case with the Shitankou-Yaoergoukou area in the middle segment of the fault, where the hanging wall of the main thrust fault with a gentle southerly dip usually developed into an antithetic thrust, which resulted in the formation of an antithetic drag fold in the Pleistocene sandy gravels. Two pronounced neotectonic movements took place along the fault from the late Pleistocene to Holocene： one occurred at the end of the late Pleistocene （13.1-13.3 ka BP）, and the other at the middle-late Holocene （-3.0-5.0 ka BP）.

关 键 词：晚第四纪 新构造活动 逆冲 反向牵引褶皱 榆木山北缘断裂 甘肃 

分 类 号：P542.3[天文地球—构造地质学] P534.63[天文地球—地质学]