南黄海盆地位于下扬子地块的东部,中、古生界研究程度较低,迄今为止尚未系统开展过龙潭组—大隆组沉积相研究,从而制约了研究区的油气勘探。本次研究结合陆上下扬子的研究成果,通过实际的钻井、地震资料分析,开展了南黄海盆地南部坳陷龙潭组—大隆组沉积相研究。结果表明:龙潭组—大隆组沉积时期研究区发育海相碎屑岩沉积,沉积体系整体呈NE向展布;自NW向SE方向水体逐渐变深;研究区的东北部发育河流相,向SE方向过渡为三角洲相、沼泽—澙湖相和前滨—临滨相,东南部为陆棚相;该套地层泥岩和煤层发育,属于良好烃源岩。
The South Yellow Mesozoic and Paleozoic and Sea Basin is located in the eastern part of the lower Yangtze Block. The the sedimentary facies of the Longtan and Dalong Formations have not been well studied so far. As the result, oil and gas exploration in this area is constrained. Combining the new research findings recently achieved in the land area of the Lower Yangtze together with the drilling and seismic data offshore, we studied the Longtan-Dalong Formations in southern depression of South Yellow Sea Basin for their sedimentary facies. Results showed that the Longtan and Dalong Formations consist mainly of marine clastic rocks and depositional systems distributed in a north-east direction in general. During the period of deposition, water became deeper from the northwest to southeast. The northeastern part was dominated by fluvial facies, which changed gradually to delta, swamp-lagoon and foreshore-shoreface facies along southeast direction. Continental shelf was developed in the southeastern part. Shale and coal were well developed in the two formations and both are good source rocks. The research has founded a good geological basis for oil and gas exploration of the Longtan-Dalong Formations.