【摘要】 运用孢粉、藻类、有孔虫等古生物综合分析方法,对比土壤微形态、沉积磁组构分析结果,研究长江三角洲地区晚第四纪古土壤层记录的古环境信息。结果表明,古土壤是海平面变化、气候、环境综合作用的产物,它的发育具有明显的阶段性。古土壤堆积阶段,海水已退出本地区,气候温暖而湿润,河漫滩经常受洪水淹没积水,多次滞水与暴露环境的交替,形成了淡水藻类与陆生植物互为消长的特殊生物组合特征。这一时期沉积与暴露成壤作用反复交替,古土壤形成了多个粘粒胶膜淀积层。此期相当于末次间冰阶向末次盛冰期过渡及海平面下降的时期,沉积后进入了持续成土阶段,海平面变得更低,气候变干,地下水面降低,古土壤已不能被淹没,持续暴露成壤,这一时期逐渐接近末次盛冰期。更多还原

【Abstract】 The paleoenvironmental information of Quaternary paleosol in the Yangtze River delta area has been interpreted on the basis of paleobiologic analysis including sporopollen, algae and foraminifer, along with micromorphologic and magnetic fabric analysis. According to the analysis result, the paleosol was the product of sea level, climate and environmental changes. The formation of the paleosol can be divided into the following stages: in the deposition stage, though the sea level dropped, the paleoclimate was still warm and humid, and the fluvial floodplain could still be submerged when flooding. Consequently, the alternation of flooding and exposition made the paleosol a unique sediment of complex genesis and paleobiologic assembly. This process happened in transition from δ18O stage Ⅲ to δ18O stage Ⅱ when the sea level was dropping. The climate became dry and the groundwater level got down, therefore the plain was no longer flooded and the pedogenesis going on. This period may be the last glacial maximum.更多还原