Characters of Changdi fault in the east of Jiyang depression and its reconstruction process
Cao Gaoshe, Bi Lei, Peng Chuansheng, Zhou Tingquan, Xu Guangming, Xing Nana, Chen Junxia
1. Institute of Resources & Environment in Henan Polytechnic University, Jiaozuo, Henan 454000;
2. State Key Laboratory of Marine Geology, Tongji University, Shanghai 200092;
3. Geology Science Research Institute of Shengli Oilfield, Dongying, Shandong 257015
Changdi fault is a representative strike-slip fault zone in the east of Jiyang depression,which included deep and shallow fault systems. The deep fault system which developed R-P faults is the main body of Changdi fault. The deep fault system manifested ribbon structural style in cross section and pigtail structural style in plane. The shallow fault system was consisted of NS-trending left-order en-echelon faults. Each fault in the en-echelon faults zone was NS-trending T-fault of strike-slip fault. The development history of Changdi fault could divide into three stages including the deposition periods during Member 3 of Shahejie Formation to Lower Member 2 of Shahejie Formation,Upper Member 2 of Shahejie Formation to Dongying Formation and Guantao Formation to Minghuazhen Formation. Because of the accommodate effect between Jiyang and Bozhong depression,Changdi fault started activities and developed deep fault system at the deposition period during Member 3 of Shahejie Formation to Lower Member 2 of Shahejie Formation. Affected by gradually thickened sedimentary cover and continuing activities of deep fault system,the shallow fault system of Changdi fault started activities at the deposition period during Upper Member 2 of Shahejie Formation to Dongying Formation. At the same time,Tanlu fault began to affect the structural pattern in study area,the activity of the fault in left-order en-echelon faults zone was enhanced and a large-scale north-trending fault zone was formed. The shallow fault system was increasingly apparent at the deposition period during Guantao Formation to Minghuazhen Formation. The NS-trending strike-slip fault gave way to the NE-trending strike-slip fault which controlled by Tanlu fault.