歧口凹陷“包心菜”构造的形成机制与演化

目的研究"包心菜"构造的结构特征和演化过程,探讨其形成和演化的动力学机制。方法运用歧口凹陷地震资料,采取平衡剖面及地震地层界面拉平方法进行综合分析。结果 "包心菜"构造为具有"凹中隆"结构的新型构造类型,一般出现于凹陷断层交汇或拐弯处;歧口凹陷内典型的"包心菜"构造为滨海1号,另外,港东断层东北端和歧东断层下降盘的"包心菜"构造也较为典型;凹陷内的"包心菜"构造在东营末期出现隆升,东营组遭受剥蚀,随后区域沉降接受沉积,在新近纪出现隆起塌陷形成"包心菜"构造。结论 "包心菜"构造的形成和演化受控于区域构造应力场和深部热作用,其形成经历了4个演化阶段:在区域挤压背景下形成隆升→隆升处地层遭受剥蚀夷平→区域沉降接受沉积→应力撤出,隆起塌陷,形成"包心菜"构造样式。

Formation mechanism and evolution of "cabbage" structure in Qikou sag

Aim To research the construction and evolution of "Cabbage" structure and analyze the dynamic mechanism of the formation and evolution.Methods Using the seismic data of Qikou sag and adopting the methods of balanced section and layer flattening in seismic.Results "Cabbage" structure is a new structure type with "uplift in sag" construction,which is generally developed in the intersections or corners of faults in sag;Binhai No.1 structure is the typical representative of "cabbage" structure in sag,and "Cabbage" structures in the northeastern end of Gangdong Fault and the downthrow side of Qidong Fault are also researched;"Cabbage" structures in Qikou sag was uplifted in the end of Dongying period followed by denudation in the Dongying formation and deposited as regional subsidence,and the uplift collapsed to form "cabbage" structure in Neogene.Conclusion The formation and evolution of "cabbage" structure are controlled by regional tectonic stress field and the deep thermal process,and the formation can be divided into four evolution stages: uplifting under regional compression→denudation planation of the strata in uplift→deposition in regional subsidence→stress withdrawal→uplift collapse to form a "cabbage" structure.