Synonym: Fen-Wei Graben
The Fen-Wei Graben is located in the area between the EW-trending orogenic belts of the Yinshan Mountains and Qinling Mountains along the Fenhe River and Weihe River. It extends north of the Qinling Mountains along the Weihe River with an EW trend to Houma and Yuncheng in Shanxi Province and then turns to a NNE trend. It is composed of a graben system with a length of 1,200 km and a width of 10–50 km. The graben system began to form in the Eocene. It continued to develop in the Pliocene and began to subside in the Quaternary. The basement of the Weihe Basin is up to 6,000 m deep, which is an indication of strong subsidence. The graben system contains numerous hot springs and is also an area of recent seismic activity. These characteristics indicate that this graben is currently an active rift zone.