摘要: |
隐性断裂带(断裂趋势带)是指盆地沉积盖层内发育的弱变形(隐蔽性较强)构造带,属于断裂带形成演化早、中期阶段的产物,由于缺乏明显的断裂面(带)和显著的位移而难以识别。在对苏北盆地、渤海湾盆地隐性断裂带研究基础上,于歧口凹陷识别出基底断裂走滑型隐性断裂带,并分析其特征、形成机制、控藏作用等。该断裂趋势带其自南向北可以分3个区段:南段基底断裂与盖层断裂体系直接连接构成花状构造;中段古近系的花状构造终止于沙二段,新近系仅发生挠曲变形,成为东西侧不同构造单元、南北部不同构造特征的平衡点;北段新近系发育的花状构造深部收敛于古近系的重力滑脱断层,基底断裂通过影响滑脱断层控制盖层断裂体系。研究结果表明,古近系基底断裂扭动作用主要以直接传递、调节传递、间接传递等3种方式控制影响盖层中隐性断裂带的形成。深部隐伏断裂切入基底,有利于热作用传递而促进烃源岩成熟;盖层中的隐性断裂带控制了沉积体系和隐蔽性圈闭的形成和分布;隐性断裂带的观点丰富了构造地质学理论,为油气勘探提供了新认识。 |
关键词: 隐性断裂带 基底断裂活动 花状构造 调节构造 滑脱构造 油气成藏 |
DOI:10.3969/j.issn.1673-5005.2016.04.004 |
分类号::TE 121.2 |
文献标识码:A |
基金项目:国家自然科学基金项目(41340008);中央高校基本科研业务费专项(14CX06069) |
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Characteristics of concealed fault zone and its significance in hydrocarbon accumulation in Qikou Sag |
ZHOU Weiwei1, WANG Weifeng2, SHAN Chenchen2
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(1.Key Laboratory of Marginal Sea Geology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China;2.School of Geosciences in China University of Petroleum, Qingdao 266580, China)
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Abstract: |
Concealed fault zones or fault trend zones formed in the cap rocks of sedimentary basin, which is influenced by the regional or local stress field, and activities in the basement rift system. A concealed fault zone is characterized by strong concealment and is associated with dominant fault zone. Based on the previous research of Subei and Bohai bay basins, using basement structure, structural framework, small dominant structure, seismic section features and coherent slices of Huanghua Sag, we recognized a NNE concealed fault zone and analyzed its characteristics, formation mechanism, and hydrocarbon accumulation potentials. The results show that the newly found concealed fault can be divided into three different tectonic deformation sections, the flower structure linked by the basement rift and the cap rock rift system in the south part; the Paleogene flower structure ended in the second member of Shahejie Formation in the middle part where bending deformations only occurred in the Neogene stratum and became the balance point of different structural units; and the flower structure developed in the Neogene stratum of north part deeply converged to gravitational detachment fault of Paleogene, where basement rift controlled the cap rock rift system by affecting gravitational detachment fault balance point. Studies show that former Paleogene basement rift twist controlled and affected the formation of concealed fault zone in the cap rock in three forms:direct transmission, regulatory transmission and indirect transmission. Deep buried faults cut into the basement, facilitating heat transfer to accelerate the maturity of source rock. Concealed fault zones in the cap rock controlled the formation and the distribution of the sedimentary system and disguised traps. The viewpoint of concealed fault zone enriches structural geology theory and provides a new understanding for oil and gas exploration. |
Key words: concealed fault zone basement fault activity flower structure accommodation structure decollement structure hydrocarbon accumulation |