【摘要】 南海北部洋陆转换带是近年来基础科学研究和深水油气勘探热点地区.本文在详细研究南海北部洋陆转换带新采集的二维长电缆深反射地震剖面资料的基础上,采用挠曲悬臂梁模型和挠曲回剥模型算法,分别计算了上地壳、地壳和整个岩石圈拉伸系数,实验结果表明,研究区洋陆转换带盆地岩石圈发生了与深度相关的拉伸变形过程,并且随深度增加,拉伸量逐渐变大,该结果解释了南海北部盆地裂后阶段发生的加速沉降现象.同时,本文结合南海北部洋陆转换带盆地发育过程的特点,将洋陆转换带盆地演化划分为陆内裂陷阶段、裂后热沉降阶段和裂后加速沉降阶段.本研究将有助于认识南海北部深水盆地特征,并对大陆边缘动力学研究和陆缘盆地深水区油气勘探有重要意义.更多还原

【Abstract】 Synthesis of deep seismic and potential field data from the northern rifted margin of the South China Sea shows that the ocean-continent transition zone(OCT) is a kilometer-scale wide zone between the shelf-break and ocean floor.We present the results from processing and interpreting one multichannel deep-penetration seismic reflection line collected during the late 2000s.A numerical backstripping calculation using 2D models flexural cantilever and sediment decompaction was performed in our study.The results show the stretching factors of the upper crust,the whole crust and the whole lithosphere are different,which indicates depth-dependent extension on the OCT of the northern margin of the South China Sea.Compared with the faulting in the upper crust,the larger extension factor of whole lithosphere has an important effect on the fast subsidence recognized in recent years.In our study,three stages of evolution of basins on the OCT of the South China Sea are established.They are the rifting in the continent,post-rifted thermal subsidence and post-rift fast subsidence stages.This work can improve understanding of the development and evolution of the South China Sea,and has significance for geodynamic research of the continental margins and petroleum exploration in the deepwater areas of the South China Sea.更多还原