Prototype basin types and segmental differential evolution of LF13 subsag in the Pearl River Mouth basin
LF13 subsag,a traditional hydrocarbon target of the eastern Pear River Mouth basin,currently faces the challenges of lacking of domain specific and large scale exploration targets.Therefore,it is necessary to conduct an integrative analysis and regional anatomy for the subsag,and carry out basic geological researches such as prototype basin restoration and structural segmentation differences.The results demonstrate that,the prototype basin of the western LF13 subsag is one typical dustpan-like half graben with faulting in the north and overlapping in the south,showing the characteristics of brittle deformation,and the western segment is of inherited half graben,but the eastern segment is a half graben with weak migration.However,the eastern LF13 subsag shows a remarkable difference in structural segmentation as follows:the western segment belongs to a migrating superimposed depression,and the late-rifting(Enping period)faulted-depression superimposed on the early rifting(Wenchang period)dustpan-like half graben,as the result of northward migration associated with magma underplating below the basement;the prototype basin of the middle segment is a faulted-depression superimposed with a wide and gentle half graben,and the depression-controlling faults are large in number but weak in activity,with the characteristics of ductile deformation,and intensively localized magma underplating are found below the basement;the prototype basin of the eastern segment is a dustpan-like half graben with faulting in the north and overlapping in the south.Based on the above prototype basin restoration,we anatomized the lateral differences in structural style and evolution of each segment,discussed the differential evolution process and deep dynamic mechanism as well,and proposed that the magma underplating and associated different thermal mechanisms account for the observed multiple prototype basins and segmental differential evolution of LF13 subsag,filling the blanks of research on thermal mechanism of continental shelf areas and differential deformation of sags in the Pearl River Mouth basin.The findings could not only deepen the understandings of basic petroleum geological conditions and lateral differences in hydrocarbon accumulation in the LF13 subsag,but also provide theoretical reference and guidance for hydrocarbon exploration in the next stage.
Pear River Mouth basinLF13 subsagprototype basindifferential evolutionmagma underplatingthermal mechanism
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