中文摘要：

通过对江汉平原北部蔡垱西剖面沉积物粒度、地球化学元素、孢粉等相关数据的综合分析,揭示了该地区约1250年以来环境演变历史。通过沉积物的野外观察、粒度数据分析及剖面所处地貌部位的综合分析认为,该剖面沉积物主要为汉江等周围水系洪水带来的泥沙泛滥至低洼平原区,并以近乎停滞的低缓流速沉积而成,所以沉积物以细粒的黏土质粉砂为主,并由于沉积物来源区存在广泛的黄土沉积分布,使得沉积物具有某些类似于黄土的沉积特征。1500年前后沉积物粒度的明显变粗和分选的明显变差,可能反映洪泛作用的增强。地球化学元素和孢粉分析结果揭示,该地区自1250年以来的气候可以划分为较为暖湿、偏干凉、较为暖湿和稍许干凉化的4个阶段。其中1500年前后出现的显著气候干凉化事件反映出明清时期气候中突出的一次降温事件,这个时间段洪泛作用增强同气候干凉化事件的对应表明气候的干凉化可能是导致洪泛过程增强的因素之一。

英文摘要：

The Caidangxi profile is in the north of Jianghan Plain,Hubei Province,China.Synthetic analysis of grain size,chemical elements and pollen of sedimentary samples from Caidangxi profile reveal the paleo-environmental changes since 1250 AD of the area.The sediments of the profile dominantly consist of clay silts.The sedimentary characteristics,such as grain size and the sorting coefficient,together with the analysis geomorphic position on which the deposition occurred,may indicate that the sediments were deposited by sheet flood mainly from Han River in a slow hydrodynamic depositional process.The sedimentary characteristics also show some similarities with the loess sediments for that some materials were derived from the loess distributed in this river basin.The grain-size and sorting have a significantly increase in 1500 AD,which might reflect the effect of the intensified flooding process.The climatic history since 1250 AD could be identified four stages by geochemical elements and pollen analysis data.The climate of four stages were respectively ＂wet and warm＂,＂cool and dry＂,＂a little wet and warm＂ and ＂a little cool and dry＂.The distinct cool and dry climate during around 1500 AD might reflect the response of an evidently lower temperature event of the Little Ice Age.It also might be one of the reasons for the intensified flood process during the same time.