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

A 74m core was obtained from Borehole CSJA3, drilled in Qindong Town, Yancheng City of Jiangsu Province. Multistratigraphic 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 Transgression’, ‘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: (P8) Cyperus-Graminea assemblage, 0~7.8m, warm and humid, salt marsh to supratidal upwards; (P7) Pinus-Chenopodiaceae-Artemisia assemblage, 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 subtidal; (P3) Quercus-Pinus-Gramineae assemblage, 43.55~50.0m, warm and humid, intertidal; (P2) Pinus-Quercus-CompositaeConcentricystes aseemblage, 50.0~65.0m, warm-cool to dry, bank-attached bar and fluvial-flood land facies.