【摘要】 为了了解南中国海南部南沙群岛陆架-陆坡区中生代地层发育情况,作者通过综合分析该海区钻井、拖网及1987年以来采集的20000多公里的多道反射地震勘探等资料,得到了对该区中生界基本特征的如下新认识:空间分布上,南沙的中生界具有从北部的郑和-礼乐隆起南缘向南增厚的趋势;沉积岩相方面,东部三叠纪时为深海相,侏罗纪为浅海与三角洲相,白垩纪为浅海-内浅海相,而往西南部中生代的海水深度有变深的趋势;中-新生代变形上,在南沙西部的曾母盆地,中生界褶皱为复式的、非协调性的,南沙中部多为舒缓褶皱,东部仅在近巴拉望海槽地带出现小幅度的褶皱。结合围区中生界及特提斯构造域的发育特征,作者提出南沙地块上的海相中生界在大地构造上归属于残留在中特提斯洋北部减薄陆缘地壳上的中特提斯期海相沉积地层,是该海域油气资源勘探不可忽视的对象。更多还原

【Abstract】 The Nansha Islands region, or geologically the Nansha Block, occupies the southern part of South China Sea. For potential energy resource targeting, the development and distribution of the Mesozoic stratigraphy on the area from continental shelf to continental slope were investigated. By studying various geological (ocean drilling and dredging) and geophysical (multi-channel seismographic reflection data in total length of over 20 000-km made since 1987) data, the Mesozoic paleogeography of the area was reconstructed. In spatial dimen-sion, the Mesozoic deposits thicken up southwards from southern border of the Zhenghe-Liyue Uplift in the north. In temporal dimension, in the Triassic, abyssal sedimentary facies developed in the east; to the Jurassic, shallow marine and deltaic facies developed; and to the Cretaceous, the area progressed into shallow marine or inner shallow marine environment deepening southwestwards. In the Meso-Cenozoic tectonics, the western part of the study region represented by the Zengmu Basin experienced multiphased and non-accordant folding; the central part showed gentle and wide folding; and the eastern part underwent small and local folding such as seen in the area near the Palawan Trough. In overall, under the scope the Tethys Realm, the Mesozoic marine deposits on the Nansha Block reflect the nature of a thinned continental margin in the northern part of the Meso-Tethys tectonic realm. Exploration to energy resources of the Mesozoic marine deposits in the area should be intensified.更多还原