The Particle Size Characteristics and Origin of Hard Clay in the  Central Area of Chenghu Lake, Jiangsu Province, China

Key words: 
• Chenghu Lake /
• hard clay /
• particle size /
• Taihu Plain /
• Yangtze River

Abstract: Chenghu is one of the shallow lakes in Taihu Plain, Jiangsu Province, China. The bottom of Chenghu is extremely flat, which is mainly composed of ‘hard clay’(a kind of sediment consisting of silt and clay), and has been featured with a NWSE paleochannel in the middle and shallow swamps in the middlewest. Sediment record in these paleochannel and swamps may become good archives, spanning from the Last Glacial to the Postglacial. This paper focuses on the hard clay of the lake bottom based on the study of the SC7 core (about 4 meters long) that drilled in the paleochannel at the bottom of the lake. The composition of the particlesize of the hard clay is discussed in detail. The hard clay in Chenghu mainly consists of fine silt, medium silt and clay; the content of fine silt from 26.7% to 38.1%, that of medium silt from 26.9% to 34.3%, that of clay from 19.7% to 26.2%, which belongs to clayey silt. The 10~50 μm particle group is the “dominate group” of the hard clay in Chenghu with the average content of 57.9%. The mean particlesize is from 6.3 to 6.9. Through the comparison of the particlesize characteristics among the hard clay in Chenghu, lake sediments, Xiashu Loess in Zhenjiang of Jiangsu Province and the northern China loesses in Qaidam, western Gansu, eastern Gansu, northern Shaanxi, western Shanxi and Shandong Province, we tend to conclude that the hard clay in Chenghu is of aeolian origin.