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根据古生物化石资料,结合岩性资料以及古构造、古地貌等,对琼东南盆地渐新统崖城组沉积环境进行了系统分析,结果表明,琼东南盆地崖城组沉积时期,中央坳陷古生物呈间歇-较连续性出现,丰度与分异度较高,为局限滨海-浅海环境,据此得到位于该一级构造单元的长昌凹陷崖城组时期为局限滨海-浅海环境.根据平面沉积充填特征、典型地震剖面,结合前人对琼东南盆地渐新统崖城组聚煤环境的研究结果,总结了长昌凹陷地堑式烃源岩发育模式,即烃源岩为凹陷边缘的扇三角洲、滨海沼泽、海岸平原煤系及凹陷中央的浅海相泥岩或泥炭层.其中,崖三段与崖一段成煤面积相对较大,更有利于煤系烃源岩的发育,崖一段近平衡浅海环境具较充足的陆源高等植物有机质来源,也具有较好的保存条件,有利于炭质泥岩烃源岩的发育.“,”According to fossils,lithology,paleo-tectonic and paleogeomorphological features,we comprehensively studied the sedimentary environment of the Yacheng Formation in the Qiongdongnan Basin.It was found that during the period of the Yacheng Formation,the fossils records in the central depression of the Qiongdongnan Basin are continuous,with high abundance and diversity,indicating a restricted shallow-sea environment in the Changchang Depression.According to the sediment filling features from typical seismic profiles,and based on the fact of coal accumulation in the Yacheng Formation,we proposed in this paper a graben source rock model for the Changchang Depression.There are two kinds of source rocks,namely the source rocks of fan delta,coastal marsh and coastal plain around the depression and the source rocks of shallow sea mud and peat layer in the center of depression.The Yacheng III and Yacheng I Formations have large areas of coal deposition,and coal source rock is well developed.There were abundant terrestrial higher plants as organic matters for the balanced shallow sea environment of Yacheng I Formation,and preservation condition was also good,of which both could contribute to the formation of carbonaceous mudstone source rocks.