长江三角洲晚第四纪地层层序特征

通过289口钻孔资料的分析，以下切河谷底部的侵蚀面及河间地古土壤层顶面为层序界面，据此将长江三角洲晚第四纪地层划分为三个层序，古河谷和古河间地的层序界面埋深相差较大，但所划分的三个层序在横向上可以进行对比，长江三角洲晚第四纪地层存在古河谷相序和古河间地等两类相序以及四种层序组合方式，其中三期古河谷充填层序具有套叠式结构，证明古河谷的发育具有继承性，且规模逐渐缩小，长江晚第四纪古河谷经历了“下切—充填—海泛—三角洲进积—再下切”的周期性发育过程

Characteristics of the Late Quaternary Stratigraphic Sequence in the Changjiang River Delta Area

The Late Quatemary stratum in the Changiiang River delta area is divided into three sequences with the seqUence boundare - the top surface of the paloosol in the inteuluve and the erosional surface under the incised valley,analyzing with Sequence Stratigraphy on 289 drilled well data. These sequences can be cormlated in transverse in spite of great height deviation between the incised valley and the intediuve. The boe Quaternary stratum is composed of incised - valley sequence and interfluve sequence which are of two basic types in four pattems. Three period incisedvalley sequences telescoping each other, which are chief characteristics of the Late Quaternary stratum, prove that three incised valley developed posthumously, but with litile and litile scale. The Late Quaternary Changjiang River incised - valley went throuth three sedimentare cycles of" incising - filling - sea spreading - delta progndation - incising again.