Analysis Of The Genesis And Tectonic Evolution Of Faults In Jinhu Sag

The northern Jiangsu Basin on the Southern China plate is one of the few continental petroliferous basins and Jinhu sag is one of the most important producing oil and gas areas of the basin,the hydrocarbon reservoir and the fault basin system has close relationship.Based on analysis of regional dynamics background,the typical profile of the structure interpretation,section and plane structural style analysis,we anlyse fault activity,tectonic evolution and focuse on the synbasinal stress field simulation,forme process numerical simulation research,then expound the causes and the evolution history of the faults system in Jinhu sag.Jinhu sag includ three fault systems of Yangcun,Tongcheng and Shigang.The fault system and basin forming period experience multi-stage tectonic evolution stage.Research shows that the West Yangcun fault(Chajian fault),Shigang fault and Tongcheng fault.They are late Cretaceous-Paleogene basin basement faults before the product of resurrection.The Shigang fault and Chajian fault formerly know as the Su-Lu orogenic belt of the Indosinian foreland deformation belt of the same thrust faults during the late Cretaceous to Paleogene basin raised by thrust faults into the basin controlling / control wa listric normal fault.The predecessor of Tongcheng fault is left lateral fault in Late Jurassic period,the translation made Chajian fault and Shigang fault produced left fault and during the late Cretaceous Paleogene basin produced the release of Chajian fault.The east Yangcun fault formed in the late Cretaceous Paleogene basin extended fault of Chajian fault.A series of evidence explain that Jinhu sag during the late Cretaceous-Paleogene basin nearly extended SN stress field in this area.In the stress background,the lateral fault in the Yangcun,Tongcheng and Shigang fault developed a series of pinnate fault or en echelon fault and a lot of of results of simulation reproduced the process of the formation and development mechanism of these secondary faults.Since the late Cretaceous of Jinhu sag has experienced multi period of basin formation and reversal events,there are three sets of bottom-up development of structural layers forming three distinct tectonic system in the section,in Taizhou-Funing period basin dispersed rifting,Dainan-Sanduo period experienced the central fault depression and Yancheng period depression stage.In Taizhou-Funing period synsedimentary extensional faults were in the start-up phase,in Dainan-Sanduo period faults produced intense activity called extensional stage,Yancheng in the period under the weak extension(SN tension)basin disappeared and faults activity tended to stop.Dainan-Sanduo and Yancheng duo sedimentary stage in the sedimentary period of Sanduo event(NEE direction extrusion)caused by a strong inversion basin.Tongcheng fault becaused of its unique orientation and the nature of the fault becoming the one thrust fault of the few in the Subei basin.On the whole,the fault system in Jinhu sag was in the evolution of multi period results controlled by basement fault.In Late Cretaceous-Paleogene period the basin during the regional north-south extensional stress field developed of a series of secondary faults,thus forming a complex fault system.In Jinhu sag,the fault system in the basin before experienced Indosinian foreland thrust and Yanshan sinistral two stages of tectonic evolution,After a period of Funing basin was in extensional stage(basin dispersion and rifting stage)and in Sanduo-Dainan period basin was in strong extensional stage(basin centraly rift stage),Sanduo event made fault in inversion stage and base in Neogene was in weakly extensional extinction stage(basin depression-subsidence stage).