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利用南海最新的重磁资料,在岩石物性分析和全海域分带变倾角化极磁异常反演磁性基底分布的基础上,选择6条典型剖面拟合反演其密度与磁性结构,在此基础上进行了深部结构的对比分析.反演中尽可能以海底地震仪探测数据(OBS)、多道地震等结果作为约束,其中FF’剖面层速度分析是利用“南海大陆边缘动力学及油气资源潜力”973项目2009年最新采集的多道地震数据,并利用了OBS2009南沙段数据对重力数据进行了物性结构拟合反演.根据剖面深部结构与物性分布特征分析认为:南海北部、南部陆缘均应以非火山型构造属性为主.北部陆缘CC’剖面以东,虽有下地壳高密度层存在并伴有活跃的岩浆活动,但缺乏典型向海倾斜反射层(SeawardDipping Reflectors)存在的证据,推断高密度层应与浅表岩浆岩一样,是海底扩张之后陆缘裂解过程中的产物.中沙隆起与礼乐盆地区的磁性基底和深部结构特征十分相似,推断在海盆拉张之前应为同一块体,属于共轭大陆边缘中的“共轭点”.西南次海盆南部陆缘地球物理综合分析表明:在陆坡坡脚附近有中生界分布,但层速度计算结果表明可能整条剖面上的中生界并不完全连续.
Using the latest gravity and magnetic data from the South China Sea, six typical cross-section fits were used to retrieve the density and magnetic structure based on petrophysical analysis and magnetic dipole anisotropy inversion over the whole sea area. Based on this, , The results of the seabed seismograph data (OBS) and multi-channel earthquakes are taken as constraints, and the velocity profile of the FF ’profile is calculated using the “South China Sea continental margin dynamics and oil and gas Resource Potential ”973 project newly acquired multi-channel seismic data in 2009, and the data of Nansha section of OBS2009 were used to perform inversion of the physical structure data.According to the deep structure and physical property distribution of the profile, it is concluded that the northern and southern parts of the South China Sea The continental margin should be dominated by non-volcanic structural properties.With the east crust CC ’profile of the northern continental margin, although there is an active crustal high-density layer with active magma activity, the typical seawardDipping Reflectors It is concluded that the high-density layer should be the same as the superficial magmatic rocks, which is the product of the continental margin pyrolysis after the expansion of the seafloor. The deep structural features are very similar and it is inferred that the same block should be formed before the extension of the sea basin and belongs to the “conjugate point” in the conjugate continental margin. The geophysical analysis of the continental margin in the southwestern sub-basin shows that at the foot of the slope There are Mesozoic distribution, but the calculation of layer velocity shows that the Mesozoic may not be completely continuous in the whole profile.