Fig. 1

The study area. a Location of the gravity network in the southwest margin of the Ordos Block. Black dots denote observation stations, red dots denote permanent GPS stations, red triangles denote absolute gravity stations, white dots denote leveling stations (Hao et al. 2014), yellow lines labeled P1–3 and DD′ denote profiles, and red lines denote faults. b Geographical position of the study area (marked by blue box). LPSF Liupan Shan fault, LBF Longxian–Baoji fault, NQF North Qinling fault, WF Weihe fault, WQF Western Qinling fault, LTF Lintan–Tanchang fault, HF Haiyuan fault, WRB West Region Block, NAB Northeast Asia Block, NCB North China Block, SCB South China Block, TP Tibetan Plateau, CBB China–Burma Block