论文部分内容阅读
随着深水油气勘探和深水盆地研究的推进,白云凹陷陆架坡折在张裂结束后发生快速跃迁、上下地壳伸展存在不均一性等一系列地质现象逐渐受到学者的关注,这些问题的解决对被动大陆边缘演化过程的认识具有重要的推动作用.根据中国海洋石油总公司(CNOOC)提供的地震地球物理数据,计算出白云凹陷地壳的拉张因子(β)分布.并选取白云凹陷内13条精确解释的长地震剖面,分别计算出沿剖面的上下地壳拉张因子,并获得拉张因子的平面分布,揭示上下地壳在拉张过程中的不同贡献.结果显示:白云凹陷全地壳拉张因子由西北向东南逐渐变大,反映了地壳由陆向洋减薄的特征.上地壳拉张因子较小,而下地壳比上地壳的拉张贡献大,表明白云凹陷新生代变形受脆性伸展作用控制不大,而主要受韧性伸展作用控制.数值模拟计算过程表明白云凹陷初始地壳应为热减薄地壳.下地壳拉张因子由北部向深海盆边缘逐渐增大,并出现两个拉张中心,分别对应于白云凹陷和荔湾凹陷.在23.8和13.8 Ma这两个时期,陆架坡折形态都与下地壳拉张因子等值圈闭的外缘走向近似,且都处于下地壳强烈变化的地区,推测由下地壳伸展和下地壳流动引起的盆地沉积沉降作用是控制陆架坡折发育位置的一个重要因素.
With the advancement of deepwater oil and gas exploration and deepwater basin research, a series of geological phenomena such as heterogeneity of the upper and lower crustal extensibility occurred on the continental slope slope of Baiyun Depression gradually became the focus of attention after the end of the fracture. These problems are solved by passive According to the seismic geophysical data provided by China National Offshore Oil Corporation (CNOOC), the tension factor (β) distribution of crust in Baiyun Depression is calculated, and 13 accurate Interpreted the long seismic sections and calculated the upper and lower crustal tensioning factors along the section respectively and obtained the plane distribution of tensioning factors to reveal the different contributions of the upper and lower crusts during the tensioning process.The results show that the global crustal tensioning factor Which shows that the crust is characterized by thinning from land to ocean.The upper crust tension factor is small, while the lower crust contributes more than the upper crust, which indicates that the Cenozoic deformation of Baiyun sag is controlled by brittle extensibility Large, but mainly controlled by the ductile extension.The numerical simulation shows that the initial crust of Baiyun sag should be a thermal thinned crust. The tension factor of the shell gradually increases from the north to the edge of the deep sea basin, and two tension centers appear, corresponding to the Baiyun sag and the Liwan sag, respectively. During both periods of 23.8 and 13.8 Ma, The outer margin of the equivalent factor traps approximates and is located in the area where the lower crust strongly changes. It is speculated that the sedimentation and sedimentation of the basin caused by the extension of the lower crust and the flow of the lower crust is an important factor in controlling the development of the slope.