基于多重地层对比研究还原长江三角洲北翼晚第四纪古环境演变

Reconstruction of the Late Quaternary palaeoenvironment on the north wing of Yangtze River Delta, based on comparative study of the multistratigraphies

对江苏省盐城市溱东镇CSJA3钻孔揭露的74m沉积物岩心进行了沉积学、年代学、生物学等多重地层研究,晚第四纪以来初步划分了 3 个有孔虫化石组合,分别对应长江三角洲的镇江海侵、滿湖海侵和太湖海侵,证实钻孔所在位置对3 次海侵事件均有记录.同-时期的7 个孢粉组合反映了不同的气候条件和沉积环境,分别为（P8） 莎草- 禾本科组合（0？7.8m） , 气候暖湿,沉积环境自下而上为盐沼- 潮上带;（P7）松- 藜科- 蒿属组合（7.8-11.0m） , 冷干,河漫滩;（P6）松- 栎- 禾本科- 藜科- 菊科组合（11.0-30.0m）,溫和略干,自下而上为河漫滩- 潮间带;（P5）环纹藻- 蒿组合（30.0-37.2m）,冷干,河漫滩;（P4）松- 菊科组合（37.2-43.55m）, 溫凉偏冷干,潮间带- 潮下带;（P3）栎- 松- 禾本科组合（43.55-50.0m）, 溫暖湿润,潮间带;（P2） 松- 栎- 菊科- 环纹藻组合,50.0-65.0m,溫凉偏干,河流边滩- 河漫滩相沉积.

A 74m core was obtained from Borehole CSJA3, drilled in Qindong Town, Yancheng City of Jiangsu Province. Multi-stratigraphic studies, which included sedimento-, chrono- and biostratigraphy, were carried out for its core sediments. Consequently, three foraminifera assemblages since the Late Quaternary were preliminarily distinguished,which corresponded to ‘Zhenjiang Trans-gression’,‘Gehu Transgression’ and ‘Taihu Transgression’, respectively. This correlation confirmed that such three transgressions all occupied the borehole area and the transgressive records were well preserved. Moreover,seven palynological assemblages,revealing variability of the climate and sedimentary environments in the same period,were composed of the following assemblages： （P 8） Cyper- us-Graminea assemblage, 0～7.8m,warm and humid,salt marsh to supratidal upwards; （P7） Pinus-Chenopodiaceae-Artemisia assem-blage, 7.8？11.0m, cold and dry,fluvial flood plain; （P6） Pinus- Quercus- Gramineae- Chenopodiaceae- Compositae assemblage, 11.0～30.0m,moderate warm and slightly dry,fluvial flood plain upward to intertidal; （P5） Ring algae-Artemisia assemblage, 30.0～37.2m,cold and dry,fluvial flood plain; （P4） Pinus-Compositae assemblage, 37.2～43.55m, warm-cool to cold-dry, intertidal to sub-tidal; （P3） Quercus-Pinus-Gramineae assemblage, 43.55～50.0m,warm and humid, intertidal; （P2） Pinus-Quercus-Compositae- Concentricystes aseemblage, 50.0～65.0m, warm-cool to dry, bank-attached bar and fluvial-flood land facies.