摘要
本文采用层序地层学基本原理,以海平面升降旋回为主线,根据300口钻井、静力触探井和分析化验等资料,探讨了杭州湾地区晚第四纪地层层序、沉积特征、控制沉积的主要地质作用及沉积层的形成过程。结果表明,该区晚第四纪地层底界面为区域不整合面,是末次冰期海面下降时形成的。晚第四系具有一个从陆相到海相再到海陆过渡相的沉积旋回,自下而上发育5套地层,即河床滞留沉积和海进河床充填沉积层序、海进河漫滩充填层序、海相层覆盖、海退河口湾及湖沼相进积层序。流水切割的古地形、海平面升降以及物源和沉积物供应量的变化,对沉积物分布起着主要控制作用。末次冰盛期低海平面时,河流下切,形成深达40～110 m的钱塘江和太湖下切河谷。冰后期以来,本区经历了早期下切河谷充填,中期海水覆盖,晚期河口湾形成、萎缩和湖沼发育过程。
The Late Quaternary stratigraphic succession, sedimentary characteristics, sedimentary processes and primary geological agent controlling Late Quarternary deposition in the Hangzhou Bay coastal plain have been studied using the sequence stratigraphic principle, and based on the date of 300 drillings, static sounding and chemical analysis etc. The results show.- the bottom boundary of Late Quaternary strata in the Hangzhou Bay is a regional surface of unconformity, which was formed during the lowering of sea level in the last glacial epoch. The Late Quaternary strata show a sedimentary cycle from continental facies to marine facies and then to paralic facies. Five sequences are developed: from bottom upward they are : channel facies, transgressive flood plain facies, neritic facies, regressive estuarine and lacustrine-swampy prograding facies. The distribution of Late Quaternary sediments was dominated by the river-cut paleotopographic relief, sea-level fluctuation and change of terrigenous supply. In the last glaciation maximum(18-15 ka B P) , the sea-level was lower and washout of river resulted in the formation of the Qiantang river and Taihu Lake incised valleys as deep as 40 to 110 m. Since the postglacial epoch, this area went through the filling of incised valley in early stage(15-7. 5 ka B P) . seawater coverage in the middle stage(7. 5-4ka R P) , formation and shrinkage of the estuarine and development of lacustrine and swampy in late stage(4 ka B P to present).
出处
《地质学报》
EI
CAS
CSCD
北大核心
1999年第2期120-130,共11页
Acta Geologica Sinica
基金
中国博士后科学基金
关键词
晚第四纪
沉积特征
沉积旋回
杭州湾
沉积过程
Late Quaternary
sedimentary characteristics
sedimentary cycle
Hangzhou Bay
