【摘要】 以珠江口盆地恩平凹陷恩平组为研究对象,在有限井控下,基于岩屑、薄片、锆石等测试资料及地球物理响应资料,综合分析研究区恩平组三级层序格架(SQ1—SQ3)内物源及其控制下滩坝沉积体系特征。采用古地貌宏观区分物源区与沉积区,运用岩屑组成及阴极发光特征明确沉积区原始物质成分,通过碎屑锆石U-Pb定年精细拾取年龄分布特征,从不同角度、层次进行物源示踪分析;同时,依据单井相、地震反射特征与多属性聚类分析刻画盆内的滩坝沉积体系特征。研究表明,研究区在恩平组沉积期发育古生代变质岩与中生代火成岩为主、元古代变质岩为辅的复合物源体系,SQ1—SQ3沉积期,北部3条大型断槽输导物源强度递增;滩坝的物源供应模式由SQ1沉积期的基岩-滩坝沉积体系向SQ3沉积期的辫状河三角洲-滩坝沉积体系转化,滩坝含砂率与含砾率递减,连片性变差,范围减小。更多还原

【Abstract】 Taking Enping Formation of Enping Depression in Pearl River Mouth Basin as research object,based on debris,slices,zircon and other test data as well as geophysical response data under finite well control,the provenances of three order Sequence Framework(SQ1—SQ3)of Enping Formation in the study area are comprehensively analyzed together with characteristics of the controlled beach-bar sedimentary systems.The paleo-geomorphology is used to divide the provenance area and sedimentary area from a macroscopic perspective.The prime material components in sedimentary area are identified based on debris compositions and cathodoluminescence characteristics.The age distribution characteristics were determined precisely through debris zircon U-Pb dating,while the source tracing analysis is conducted from difference perspectives and levels.Meanwhile,the characteristics of beach-bar sedimentary system within the basin are described based on single well facies,seismic reflection characteristics and multi-attribute cluster analysis.The results indicate that a complex provenance system was formed in Enping Formation of the study area during the sedimentary period,i.e.,dominated by Paleozoic metamorphic rocks and Mesozoic igneous rocks,and supplemented by Proterozoic metamorphic rocks.From SQ1 to SQ3,the conductivity provenance intensities of three large faulted troughs in the north were enhanced gradually.The provenance supply mode of beach bar was transformed from bedrock-beach bar sedimentary system in SQ1 to the braided river delta-beach bar sedimentary system in SQ3.Moreover,the sand content and gravel content of beach bar decreased gradually,leading to poor continuity and small scope.更多还原