南海东北部中生代海相地层的分布及其地质地球物理特征
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摘要
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。
In the four geological structure units in northeastern part of the South China Sea, including Zhu I Depression of Zhujiangkou Basin, Dongsha Uplift, Chaoshan Depression and Taixinan Basin, developed early Cretaceous and early Jurassic marine strata. The marine strata have the seismic characteristics of large dip, middle frequency, and moderate continuity. The individual velocities calculated from stack velocities are between 4.3 and 5.0 km·s -1 . Those strata, which have structural features of downwarping type depression, are quite different from the Cenozoic strata with features of filling faulting type one. The residual Mesozoic sediment is 4 000 to 5 000m thick. The Dongsha—Penghu—Beigang Uplift Belt where Tethys died out is a suture belt between South China and South China Sea blocks, with a high magnetic anomaly and thick crust.
In the four geological structure units in northeastern part of the South China Sea, including Zhu I Depression of Zhujiangkou Basin, Dongsha Uplift, Chaoshan Depression and Taixinan Basin, developed early Cretaceous and early Jurassic marine strata. The marine strata have the seismic characteristics of large dip, middle frequency, and moderate continuity. The individual velocities calculated from stack velocities are between 4.3 and 5.0 km·s -1 . Those strata, which have structural features of downwarping type depression, are quite different from the Cenozoic strata with features of filling faulting type one. The residual Mesozoic sediment is 4 000 to 5 000m thick. The Dongsha—Penghu—Beigang Uplift Belt where Tethys died out is a suture belt between South China and South China Sea blocks, with a high magnetic anomaly and thick crust.
引文
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