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南海东北部的珠江口盆地珠一坳陷、东沙隆起、潮汕坳陷和台西南盆地等 4个地质构造单元中 ,除发育巨厚新生代地层外 ,还发育并保留较厚的早白垩世和早侏罗世海相地层。这些地层的地震反射特征表现为大角度倾斜、可连续追踪和中低频的反射层序。由叠加速度推算的层速度为 4 3— 5 0km·s- 1 。这些中生代地层具坳陷型沉积特征而与新生代断陷型充填式沉积明显不同 ,残存厚度约 40 0 0— 5 0 0 0m。东沙—澎湖—北港隆起带是中生代华南地块与南海地块的缝合拼接带。该拼接带显示为地壳增厚和高磁异常 ,古特提斯在此消亡。
Among the four geotectonic units in the Pearl River Mouth Basin in the Pearl River Mouth Basin in the northeastern South China Sea, such as the Jurassic Cenozoic strata, the Dongsha uplift, the Chaoshan depression and the Taiwan-Southwest basin, thicker Early Cretaceous Early Jurassic marine strata. The seismic reflection features of these strata are characterized by large-angle tilting, continuous tracking and low- and medium-frequency reflection sequences. The layer velocity estimated from the superposition velocity is 4 3- 5 0km · s-1. These Mesozoic strata have the characteristics of depression-type sedimentation but distinctly different from the Cenozoic fault-type filling deposits, with a residual thickness of about 40 0 0-5 000 km. The Dongsha-Penghu-Beikang uplift belt is a stitching and splicing belt of the Mesozoic South China Block and the South China Sea Block. The splicing band showed thickening of the crust and high magnetic anomalies, the ancient Tethys died.