苏北废黄河三角洲地区浅表沉积物特征和指示意义

Shallow sedimentary characteristics and the indicative significance in the Old Huanghe delta,northern Jiangsu Province

苏北废黄河三角洲是中国东部沿海研究海陆交互作用的重要区域,在该区域开展槽型钻和基坑剖面调查,同时采集泥炭层样品进行^(14)C测年,结果显示废黄河三角洲区域浅表主要分布以淤泥质黏土、黏土或砂黏互层的“千层饼”状沉积物为主的潮坪-潟湖-砂坝相沉积层,以及以细砂、粉砂等砂质为主的废黄河沉积层,其形成时间分别为5—7 ka B.P.(中全新世早—中期)及12—19世纪黄河夺淮期间。因此认为全球性气候变化是废黄河三角洲区域沉积环境演变的主导因素,中全新世早—中期全球性的气温升高和降雨增多造成入海沉积物的增加,形成了全区广泛分布的以潮坪、潟湖、砂坝等微地貌为主的海陆交互相沉积;12—19世纪黄河夺淮期间携带大量泥沙入海,与人类改造活动共同控制了废黄河三角洲现代地貌的形成。

The Old Huanghe(Yellow River)delta in northern Jiangsu Province is an important area for the study of land-sea interaction along the east coast of China.Trough drilling and foundation pit profile survey were carried out in this area meanwhile peat samples were collected for ^(14)C dating.The results show that the shallow surface of the Old Huanghe delta area is mainly distributed in the tidal flat-lagoon-sand bar facies sedimentary layer dominated by silty clay,clay-clay or sand-clay interlayer,and the Old Huanghe sediment layer dominated by fine sand,silty sand and other sand.The formation dates were 5-7 ka B.P.(the early and middle periods of Middle Holocene)and 12th-19th century when the Yellow River seized the Huaihe River.Therefore,it is believed that global climate change is the dominant factor in the evolution of sedimentary environment in the Old Huanghe delta region.The global temperature rise and rainfall increase in the early and middle periods of Middle Holocene resulted in the increase of marine sediment,which formed a wide distribution of micro-landforms such as tidal flat,lagoon,sand bar and so on.During the period from 12th to 19th century when the Yellow River seized the Huaihe River,it carried a large amount of sediment into the sea,which together with human reconstruction activities controlled the formation of the modern landform of the Old Huanghe delta.