Core Complex and Detachment Structure in the Kaiping Sag,Pearl River Mouth Basin and a Discussion on the Dynamics
The Kaiping sag within the Pearl River Mouth basin,northern South China Sea rifted margin,shows a complex rift structure,and the rift structure and dynamics are the main factors that hinder our understanding on the petroleum geology and exploration process in this area. Based on the newly acquired 3D seismic reflection data,this study investigates the structure of the Kaiping sag,the geometric and kinematic characteristics of boundary faults,and the deep lithospheric structure. It is revealed that the Kaiping sag has a detachment structure related to core complex,and the E-W extending dome structure in the central part of the Kaiping sag is a standard oceanic core complex structure. The development of the core complex is related to the uplift of the ductile crust,which is exposed and truncated at the KP9 high. The detachment in the context of core complex uplifting controls the structural styles and sedimentary filling process in the Kaiping sag. The development of the Kaiping core complex shows a standard rolling-hinge model,and the domed layered seismic reflectors within the crust represent the brittle-ductile transition surface in geological history,which has a direction of migration same with the hanging-wall movement. The main detachment fault shows "spoon-shaped",and a large number of SN-trending corrugations on the detachment surface indicate top down to the south slip of the hanging wall. The development of oceanic core complexes in the Kaiping sag is closely related to the existence of a weak middle crust layer within the initial lithosphere in this area. This research offers a new explanation on the rift structure and dynamics of the Kaiping sag,which has promoted the understanding on source rocks and hydrocarbon accumulation and provided important guidance for the first commercial exploration breakthrough in forty years.
core complexSouth China SeaPearl River Mouth basinKaiping sagrift structurepetroleum geologygeodynamics
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NSTL
万方数据
