中文摘要：

根据钻孔中沉积物性状的详细描述、样品粒度分析资料，结合已有黄河下游历史变迁及沉积物测年成果，分析了公元前602年到公元11年黄河下游冲积平原的沉积特征和沉积环境的变化。发现可以利用沉积物颜色、组成、粒度组成变化比较准确地确定研究区公元前602年的古地面，砂粘比Kd值是确定界线的很好指标。公元前602年以后的黄河冲积平原沉积物以浅黄色、黄色、棕色砂质亚沙土和粉质亚粘土为主，少量粉质亚沙土，平均粒度范围为3．31～6．12中，分选较差，偏度多为正偏或极正偏，峰态为窄峰、很窄和中等峰态。总体上由上游到下游平均粒径逐渐变细，标准离差增大，峰度减小，即水动力减弱，分选程度降低。对比分析发现，古黄河冲积平原沉积与现代黄河河漫滩沉积样品相比粒径明显偏细。钻孔Kd值随深度的变化揭示，从公元前602年到公元11年，黄河下游冲积平原沉积环境的水动力条件发生了两次明显的强弱变化。

英文摘要：

Using detailed description of deposits in six boreholes, grain size analysis data of sediment samples, results of previous studies on historical changes of the lower reaches of the Yellow River and dating results in the study area, we investigated the sedimentation characteristics and environmental changes in the floodplain of the lower reaches of the Yellow River from 602 BC to 11 AD. It is found that the ancient ground surface around 602 BC can be determined exactly by integrating the evidence such as changes in color, composition, texture, and grain size of the sediment samples from the boreholes in the study area, and the parameter Kd can also be used as a good indicator of the boundary. The sediments accumulated on the floodplain of the lower reaches of the Yellow River after 602 BC are mainly composed of light yellow, yellow, brown silt, sandy silt, and silty clay. They are characterized by poor sorting, with an average grain size of 3.31 to 6. 12Ф, a positive or very positive skewness, and a medium, narrow, and very narrow kurtosis. From the upper reaches to the lower reaches of the Yellow River, the average grain sizes become finer, and standard deviation increases and kurtosis decreases, indicating a decrease of both hydrodynamic forces and sorting. The results of non-parameter analyses show that the deposits, accumulated from 602 BC to 11 AD are markedly finer than those in the modern floodplain of the lower reaches of the Yellow River. The variations in the Kd value of deposit samples indicate that the hydrodynamic forces changed at least twice during the period from 602 BC to 11 AD.