临潼—长安断裂带的几何结构及形成机理

Geometric structure and formation mechanism of Lintong-Chang'an fault zone

根据野外大量断层露头以及人工地震结果表明,临潼—长安断裂带主要由两条断层组成,即麻街—碾湾断层和胡家沟—首帕张断层.麻街—碾湾断层,在灞河右岸的高桥分出一条分支断层,即王家碥—侯家湾断层;胡家沟—首帕张断层在铜人塬和少陵塬分出一条分支断层,即冢底村—唐家寨断层.断裂表现为张性倾滑正断层性质,平面上局部范围大致呈平行等间距展布,剖面上向西北呈阶梯状降落,成"Y"字型组合.深地震反射结果显示,该断裂深约5—8km,为基底断裂,深部为铲形正断层.临潼—长安断裂带是在近南北向引张应力场的作用下形成的典型的伸展断裂系,同时受余下—铁炉子断裂左旋走滑运动的影响,使断裂带从东北向西南呈帚状展布形态.

The results from investigation of large quantity of fault outcrops and artificial earthquakes suggest that the Lin-tong-Chang＇an fault zone mainly consists of two faults. One is the Majie-Nianwan fault that separates a branch of Wangjiabian-Houjiawan fault on the right bank of the Bahe River the other is the Hujiagou-Shoupazhang fault that separates a branch of Zhongdicun-Tangjiazhai fault in Tongrenyuan and Shaolingyuan. As tensile dip-slip normal faults, the faults distribute with approximately parallel equal intervals in local regions and the profiles drop in a step-like form to the northwest, presenting a Y-shape combination. The result from deep seismic reflection indicates that the fault is about 5-8 km in depth, which is not only a basement fault, but also a listric normal fault in the deep stratum. The Lintong-Chang＇an fault is a typical outstretching rift system under the NS-trending tensile stress field. At the same time, affected by the sinistral strike slip of the Yuxia-Tieluzi fault, the fault extends like a broom from the northeast to the southwest.