江汉平原江陵湖泊沉积物粒度特征及气候环境意义

Grain-size Characteristics and Their Environmental Significance of Jiangling Lake Sediments in Jianghan Plain

以江汉平原江陵湖泊沉积物为研究对象，结合沉积物岩性、粒度组成、孢粉和有机碳同位素等，分析了江陵湖泊沉积物粒度组成特征及该区域近9000a来的气候环境变化。研究发现，江陵湖泊沉积物记录了该区湖泊水体逐渐减小直至消亡的过程．气候环境变化大致可分为以下5个阶段：（1）8900～6300aB．P．为水体较深、面积较大的开阔湖阶段，气候暖湿；（2）6300～4700aB．P．为面积较小、水体较浅的潴水湖阶段，气候干旱；（3）4700～3400aB．P．为面积更小、水体更浅的洼地湖阶段，气候偏暖偏湿；（4）3400～2500aB．P．为湖沼泥炭发育阶段，气候暖湿；（5）2500aB．P．以来，由湖泊及湖沼堆积转化为洪水漫滩堆积，古云梦泽开始萎缩，气候变干。江陵湖泊沉积物粒度所记录的区域气候干湿变化与国内邻近区域（特别是鄱阳-洞庭湖区）显示出较好的一致性，沉积物粒度研究是恢复区域古降水等气候环境变化的有效途径。

As a main geology body recording a large amount of information on paleoclimate environ- ment changes, lake sediments continuously and sensitively record information of regional climate and environment with annual to decadal resolution. The sediments were sampled from Jiangling section, located in Jiangling County, Jianghan Plain. Based on the high-resolution sampling and the analysis result of sedimental lithology,grain size, pollen and the isotope of organic carbon the grain-size characteristics of Jiangling lake sediments have been analyzed and the paleo-climatic changes over last 9 000 years in the area have been reconstructed. The research result shows that the lake sediment in Jiangling lake has well recorded the drying-up process of water body and climatic changes can be divided into five stages as follows： 8 900-6 300 aB. P. when the lake was deep and open with wet climate; 6 300-4 700 aB. P. when the lake was shallow with arid climate; 4 700-3 400 aB. P. when the lake was much shallower with the a little wetter and hotter climate; 3 400-2 500 aB. P. when the limnic peat was widely developed with hot and wet climate; 2 500 aB. P. to current when the with arid cliamte. The climatic changes over 9 000 aB. P. lake was changed towards the flood deposition in Jiangling area were coincident with other research results in neighboring areas,especially the Dongting lake. The sediment gain size provides a new effective way to recover the climate changes.