绰墩遗址古今水稻土黏土矿物特征比较研究

Clay Mineral Characteristics of Ancient Paddy at Chuodun Site in Yangtze River Delta

在江苏绰墩山遗址考古发掘中,发现了在剖面不同深度埋藏的距今约6 000年的史前水稻土层、距今约3 000年的商周史前的古水稻土层和现代水稻土层。本研究为了比较古今水稻土黏土矿物特征的差异,以土壤剖面P01(包含史前古水稻土、商周史古水稻土和现代水稻土)与P03(仅含商周时期古水稻土和现代水稻土)为对象,测定其各种形态铁锰氧化物含量和黏粒矿物组成。对绰墩遗址两古水稻土剖面黏土矿物特征进行研究,结果表明:古今水稻土全铁含量的差异较小。与6 000年前古非水稻土相比,6 000年前古水稻土剖面出现铁锰和蒙皂石类矿物随水流失的现象。古今水稻土黏土矿物组成都是以水云母和蒙皂石为主,但是古水稻土1.41 nm的过渡性黏粒矿物强度低于现代水稻土。现代土壤和古土壤中黏土矿物的演变规律相似,为水云母→蛭石、绿泥石→蒙皂石。

Two layers of ancient paddy soil and one modem paddy soil were discovered in archcological excavation of Chuodunshan Relics in Kunshan, China. One of the ancient paddy soils could be ascended to 6 ka BP （prehistoric） and the other to 3 ka BP （Shang-Zhou Period）. Two soil profiles, not far apart, named P01 （containing both ancient paddy soil layers and the modem paddy soil layer） and P03 （containing only the latter ancient paddy soil layer and the modem paddy soil layers） respectively, were fixed and soil samples were collected according to soil color and texture. In order to compare the difference of clay mineral characteristics between ancient paddy soils and modem paddy soil, the contents of iron oxides and manganese oxides and the constituents of clay mineral were analyzed. The results showed that there was no difference in total iron content between ancient paddy soils and modem paddy soils. Compared to ancient non-paddy soil （6 ka BP）, some of the iron oxides, manganese oxides and smectite were lost in the profile of ancient paddy soil （6 ka BP）. The mineral constituents in ancient paddy soil and present paddy soil were very similar, but the contents of 1.4 nm mineral in ancient paddy soil was lower than that of modem paddy soil. The evolution of clay minerals were similar between modem and ancient paddy soils： both were from hydromuscovite to chlorite and vermiculite and then to smectite,