在河流不断向前推进的海退条件下可形成粒度向上变粗的进积型剖面结构和沉积层序，而在海侵条件下则形成相反的退积型制面结构和沉积层序。一般以具有进积型创面层序的三角洲保存较完整，其沉积层序自下而上依次为:底部为前三角洲泥，向上变为三角洲前缘的砂和粉砂、夹粉砂质泥: 最上部为三角洲平原沉积。具有典型的进粒序结构。除了分流河道砂体外，还有天然堤粉砂、分流间湾泥及沼泽泥发等组合。
在古河谷沉积层序中存在着多种沉积间断。
There exited many types of the depositional gap within depositional sequence.
油气盆地、沉积层序与油气系统的研究属于不同层次的油气资源评价的基础研究。
Hydrocarbon evaluation analysis is based on different level research, such as basin analysis, sedimentary sequence analysis, and petroleum system analysis.
依据生物地层学资料和层序顺序，将这些层序与台地相区沉积层序逐一进行了对比。
The correlation between these sequences and the depositional sequences of the plat were given on the basis of biostratigraphic data.
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