The Pedogenic Features Of Chuodun Paleosol In Kunshan, Jiangsu Province, And Its Environmental Implication

Paleosol indicated different time-scale regional and global environmental change. Paleosol profile at ancient human occupation can be used to study human activities, environmental change and their interaction. The Chuodun site is a very good paleosol profile for this propose. It is hard to find a paleosol at long-term human occupation regions.From the first excavated in 1982, many pleasing results from archaeology and palynology have been achieved in Chuodun agriculture site. Whereas, Archaeologists are interest in cultural relic than paleosol. Resulting in controcersial views whether there exists pale-paddy soil or not. So, it is necessary to study the paleosol and its formation environment at the site.In this paper, two 2m longs paleosol profile, located in the Chuodun site, an ancient agriculture site in Kunshan, Jiangsu. was studied. Through systematical study of grain size distribution, magnetic susceptibility and concentrations of clay minerals, the following conclusions are drawn:1, The origin of the Chuodun paleosol was elucidated by grain size distributions in this paper. Results show that the Chuodun paleosol mainly consists of fine particles less than 50 urn, with little of particles over 100 um. The "dominant sub-population" of the Chuodun paleosol is particle group between 10um and 50μm, content ranging from 46.47% to 63.52%, with the average content of 56.32%. The average contents of particle groups are 22.89% for < 5μm, 15.69% for between 5-10μm, and 5.10% for > 50μm, respectively. The grain-size analyses indicate that the grain size composition of the Chuodun paleosol is well correlated with that of the Xiashu loess in Zhenjiang. It can be deduced that the parent material of the Chuodun paleosol might be eolian Xiashu loess.2, A soil formation index(SI) was developed to quantitatively measure the degree of paleosol development. Results showed that Chuodun p1 profile consists four different layers. There was loess from 200- 160cm, pale-paddy soil from 160- 100cm, paleosol from 100 - 40cm and paddy soil from 40 - 0cm.3, Variations in total organic carbon (TOC), total nitrogen (TN) and clay mineralogy with depth of p1 profile from Chuodun. showed gradual increase TOC and TN and their ratio (C/N), kaolinite contents and their ratios to illite, K/I, with gradual decrease contents...