Distribution and structural characteristics of the Xi’an Section of the Weihe Fault

Abstract

The results of seismic deep reflection, high resolution refraction and shallow artificial seismic exploration indicate that the fault on the northern bank of the Weihe river is composed of two faults, one is the Yaodian-Zhangjiawan fault and the other is the Chuanzhang-Zuitou fault. The 22 km long Yaodian-Zhangjiawan fault of EW-striking starts from Chenjiagou via Yaodian town, Qianpai village, Bili village, Wujia town and Zhangjiawan to Jiajiatan. The 15 km long Chuanzhang-Zuitou fault striking near EW starts from Chuanzhang via Mabei to Zuitou. The Weihe fault offset the basement and upper crust, the reflecting layers of TQ, TN, TE and Tg are ruptured at depth of about 15 km. In the deep part, the Weihe fault and the secondary fault form a Y-shaped structure or a synthetic low angle intersection. The Weihe fault is a listric normal fault. The fault has obvious structural characteristics of a reversed-drag normal fault and a normal drag normal fault with the depth of 1 000 m, and also has the characteristics of syngenetic sediment. The Weihe fault is one of the faults which control the basin sediment, and it is the boundary fault of Xi’an depression and Xianyang salient. The depth of the fault decreases from the west to east gradually, the deep part intersects with the Lintong-Chang’an fault at the intersection part of Weihe River, Jinghe River and Bahe River and the shallow part connects with the Weinan-Jingyang fault. The seismic exploration results indicate that no fault exists on southern bank of the Weihe River.