Differential tectonic movement of Yanchang Formation in southwestern margin of Ordos Basin and its geologic significance

Huanxian-Zhenyuan area is one of the major exploration areas in southwestern margin of Ordos Basin in recent years.Some newgeology phenomenons appeared and were cared in the exploration.Based on the analysis of tuff,seismites and limestone gravel in Chang 7 to Chang 6 reservoir and thicken layers in Chang 7 to Chang 1 reservoir,it is believed that areal tectonic setting during Chang 7 to Chang 6 depositional stage is different from that during Chang 9 to Chang 8 depositional stage,which results in different formations,different sequence,different sedimentary settings,different lithologies and different reservoir properties.Different exploration methods are proposed for different layers and different reservoirs.