珠江口-琼东南盆地深水区古近系共划分出三套沉积层序,即始新统-文昌层序,恩平-崖城层序和珠海-陵水层序。综合应用单井相、地层等厚图、地震相平面图、地震砂岩指数平面图,参考断陷盆地沉积体系发育特征,结合构造背景,综合编制了全区各个体系域的沉积相平面图。南海北部深水区始新统发育三个大型的湖泊区,东部为白云凹陷,西部为松南-宝岛凹陷和陵水-乐东凹陷,该时期表现出比较明显陆相断陷湖盆的分隔性,除了三大湖盆外,还发育5—6个小型湖泊。渐新世早期海进区域集中在琼东南盆地,海水可能从东西两个方向进入琼东南盆地,形成东西两个浅海区,中间有浅海相和剥蚀区分隔;东部白云凹陷未发育海进,保持湖泊环境;顺德-开平凹陷亦为湖泊环境,由独立的湖泊相逐渐扩大为连片湖相沉积。渐新世晚期全区发生海进,但海进方向存在差异,东部白云凹陷一顺德一开平凹陷的海水可能由东部进入,由东向西海进;西部琼东南盆地可能存在东西两个海口,海水从两地进入盆地,继承崖城期的海进方向。
Three sedimentary sequences have been divided in the deep water area from the Paleogene system of Zhujiangkou-Qiongdongnan basin, i.e. Eocene Wenehang, Enping-Yacheng and Zhuhai-Lingshui sequences. In combination with the data from well facies, strata isopach, seismic facies and seismic sandstone index maps, together with depositional characteristics of faulted basin and tectonic background, the integrated sedimentary facies maps have been figured out for each systems tract in the study area. Three large lacustrine area were developed in the deep water area around the northern part of South China Sea, including the Baiyun depression in the east, Songnan-Baodao depression and Lingshui- Ledong depression in the west. During this period, the segment features were obvious,i, e. five or six small-scaled lakes were also developed apart from the three large lake basins. During the early Eocene, the sea transgression area was mainly in Qiongdongnan basin, and sea water was probably flushed into the basin from both the west and east directions to form two shallow sea areas divided by the erosion area while the Baiyun depression was not influenced by sea transgression to keep lacustrine environment. At the same time, Shunde-Kaiping depression also maintained the lacustrine environment which was gradually enlarged from small lakes into the united giant lake. During the late period, the overall sea transgression took place in the study area, but there existed the difference of transgression directions, e.g. the sea water emplaced from the east in the Baiytm-Shunde-Kaiping depression, and there might exist two sea mouths in the Qiongdongnan basin for sea transgression which inherited the sea flushing direction of Yachengnian.