摘要
渤中凹陷是整个渤海湾盆地的沉积和沉降中心,古近纪时期被石臼坨凸起、沙垒田凸起、渤南低凸起、渤东低凸起所环绕。凸起与凹陷之间因控盆断裂发育程度及活动速率的差异,形成复杂的构造带与沉积体系。在地震精细解释基础上,计算主要边界断裂在不同时期的活动速率,并与相应时期平面沉积体系的展布特征相对比。结果表明,渤中地区古近纪的控盆断裂活动速率峰值出现在沙三段和东三段沉积时期,凹陷处于强烈断陷期,且因平面上不同位置断裂活动强度的差异,凹陷在空间上并非呈简单的"平底锅"形态。盆缘碎屑沉积体系类型明显受控于断裂内侧的基底沉降速率,并随活动速率的大小变化而发生退积或进积。与环渤海湾陆上油田所处各凹陷古近纪的构造沉积演化相比,在东三段沉积期发生的最强烈断陷和在东二上-东一段沉积期发生断坳转换以后,成为整个渤海湾盆地远源三角洲的进积中心,是渤中凹陷古近纪构造沉积演化方面最突出的特征。
The Bozhong sag,the center of tectonic subsidence and deposition in the Bohai Bay Basin,was surrounded by the Shijiutuo uplift,Shaleitian uplift,Bonan uplift and Bodong uplift of Paleogene.Complicated tectonic belts and sedimentary systems were developed between uplifts and sags due to differentiated movement of basin-controlling faults which were under different mobility rate.Based on the detailed interpretation of 3Dseismic profiles,we calculated the mobility rate of main boundary fault in different depositional stages,and compared the distribution patterns of the deposits.The results suggest that the peak of fault mobilization occurred in the deposition stages of Es3 and Ed3 when the Bozhong Sag was intensely rifted.In a plane view,the Bozhong sag did not exhibited in a typical pan-like due to the difference of fault mobilization at different locations.The sedimentary facies at basin edge were controlled obviously by the fault activity rate.Progradation of the clastic deposits alternated with retrogradation in accordance with the change in fault activity rate.Compared with others,the tectono-depositional evolution of the Bozhong sag in Paleogene was characterized by strongly rifting at the deposition stages of Ed3.The rift then became a depocenter of a remote delta at the Bohai Bay basin after the rift turned into a depression during the depositional stages of upper Ed2 and Ed1.
出处
《海洋地质与第四纪地质》
CAS
CSCD
北大核心
2016年第4期85-92,共8页
Marine Geology & Quaternary Geology
基金
国家"十二五"科技重大专项"渤中凹陷油气成藏规律及勘探方向研究"(2011ZX05023-001-013)
关键词
断裂
活动速率
沉积体系
古近纪
渤中凹陷
fault
activity rate
sedimentary system
Paleogene
the Bozhong Sag
