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综合运用钻测井和三维地震资料,对陆丰凹陷东部缓坡带文昌组层序地层格架、坡折带类型及层序样式进行了详细探讨,认为古近系文昌组自下向上可划分为5个三级层序,代表了一个由弱到强再变弱的完整裂陷旋回.陆丰凹陷东部缓坡带文昌组层序构成样式划分为3类6种:斜坡型(平缓斜坡型和翘倾斜坡型)、挠曲型(先存潜山挠曲型和沉积地形挠曲型)和断阶型(二级断阶型和多级断阶型),并分别建立了相应的层序地层模式.研究结果表明:初始断陷时期,断裂活动弱,陆丰凹陷缓坡带总体表现为平缓的斜坡地貌特征,坡度约0.8°~2.0°;断陷强烈期,岩浆作用活跃,同沉积断层差异性活动,形成二级和多级断裂型以及岩浆底辟改造斜坡型坡折带,在深湖背景下发育众多低位砂及高位滑塌砂体,地震反射以丘形为特征,钻测井显示厚层泥岩夹薄层细砂岩;弱断陷期,受控于断层活动减弱以及前期的岩浆底辟活动的影响,整体在缓坡带发育差异明显的多种层序样式,缓坡带北段发育先存潜山型挠曲坡折带(坡度约3.8°~6.0°),控制发育厚层S型地震前积的低位扇体,是研究区有利的勘探目标;断陷衰弱期,断裂活动近乎停止,大部分同沉积断层停止活动并转化为地形挠曲坡折带,辫状河三角洲推进距离远,整体为一套富砂沉积,可见红色泥岩夹层.
Based on comprehensively using the drilling and 3D seismic data, the sequence stratigraphic framework, slope break zone types and sequence patterns of the Wenchang Formation in the gentle slope belt of eastern Lufeng Depression are discussed in detail. The Paleogene Wenchang Formation can be divided into 5 A third-order sequence represents a complete rifting cycle from weak to strong and then weakened. The sequence composition of the Wenchang Formation in the gentle slope belt in the eastern part of the Lufeng Depression is divided into three types and six types: slope type (gentle slope and tilted slope (Pre-existing buried flexure and sedimentary topography deflection type) and the fault type (second grade and multi-level fault type), and the corresponding sequence stratigraphic model was established. The results show that the fault activity is weak during the initial fault depression, and the gentle slope belt of Lufeng Sag generally shows gentle slope topography with a gradient of 0.8 ° ~ 2.0 °. During the intense fault depression, the magmatic activity is active and the differential activity of the same sedimentary fault, Forming secondary and multistage fracture types and magmatic diapir transformation slope slope break, in the background of deep lacustrine development of a large number of low-lying sand and high slip sand bodies, the seismic reflection is characterized by mound, drilling and logging shows thick mudstone Thin thin sandstone sandstone; weak faulted depression controlled by the fault activity Weak and pre-magmatic diapirism, there are a variety of sequence patterns with obvious differences in the development of the gentle slope belt. In the northern part of the gentle slope belt, the latent buried hill type flexural slope break (about 3.8 ° ~ 6.0 °) Controlling the lower fan body of the pre-thick S-type earthquake is the favorable prospecting target in the study area. During the weakening period of fault depression, the fault activity almost stopped and most of the synsedimentary faults ceased to be transformed into the topography flexural slope slope and the braided Pujiang River Delta to promote a long distance, the overall set of rich sand deposition, visible red mudstone interlayer.