Research On The Structural Feature During Rifting In The Western Baiyun Sag,Pearl River Mouth Basin

Baiyun Say is the biggest basin which is located in the deepwater aera of Peral River Mouth Basin,which is situated in northern South China Sea.It is also a significant research point of shelf-edge,sequential stratigraphy,deepwater fan and crust-mantle boundary study.Western Baiyun Sag is located in the northwest of Baiyun say.Compared with Baiyun Main Sag,the Western Baiyun Sag has a later and slighter deformation and thinner stratum.Its rifting time is the most remarkable transformation time,and has a very important meaning for the study of no matter its structural feature or the Pearl River Mouth Basin and South China Sea.This thesis is based on the interpretation of 2D and 3D seismic data,so as to analysis the feature of fault system.By analysing the destance-displacement line,balanced cross section,fault growth index,three-dimensional simulation,etc,we could analysis the characteristics of deformation during rifting.By analysing stereographic projection,rose diagram,etc,we could study the feature of force during rifting.As a consequence,we get some main results:(1)Western Baiyun Sag has different fault feature,such as planar fault,listric normal fault and ramp-flat fault.The main fracture system in echelon inclined column.(2)The boundry fault of Baiyun-three Sag is mainly controlled by tension-torsional stress,and the strongest defomation was happened during Wenchang time.The boundry fault of Panyu-25 Sag showed the feature of split-connection faults,and its strength slower in Enping time.(3)The main structure is half graben,and Baiyun-three Sag was controlled by multiperiod and multistage listric normal fault.(4)The main structure of north side of eastern Western Baiyun Sag is faulted and south side is overlapped,and has tectonic division at the same time.This feature might have something to do with transformation belt.(5)The force feature of Western Baiyun Sag is different in Panyu-25 say and Baiyun-3 say,and also has twist during Wenchang and Enping time.