Characteristics of gravity and magnetic field in Weibei uplift of Ordos basin

This paper neatened and studied the gravity and magnetic measurement data in the study area. It used these data in combination with drilling, geological, electrical and seisimic results in the study area.The distribution of gravity and magnetic anomalies have been discussed, the faulting structures have been speculated, the tectonic units of the study area have been divided and the favourable areas for oil shale have also been predicted.The results showed that gravity and magnetic fields have the following basic features:"high in the east and low in the west, high in the center and low in the south and the north, the high and the low are alternated".The main fault of the study area is NE-trending.Nearly EW and NW-trending secondary faults cut off the main fault, forming "多"-shaped tectonic features.According to significant differences on north-south and east-west, Weibei uplift can be divided into 6 tectonic units, such as Yijun-Huanglong ramp zone, Tuqiao-Zhaojin fault fold belt, Bin county-Lingtai fold belt, Linyou-Yong shou fold belt, Yao county-Chengcheng fault-fold belt, Heyang-Chengcheng fault-uplift belt. Trissic in Yi jun-Huanglong ramp zone and Yao county-Chengcheng fault-fold belt has wide area, distributional stability, large sedimentary thickness and hydrocarbin source rocks. They may be favourable exploration target zones for Triassic Yanchang Formation in the study area.