昆山绰墩古土壤粒度特征及母质判别

Particle-size Features of Chuodun Paleosol and Identification of Its Parent Material

自第四纪晚期以来，来自黄土高原的粉尘在风力作用下不断向东南扩张，在长江中下游地区形成了下蜀黄土。太湖流域的部分水稻土就是在下蜀黄土之上发育的。本文对绰墩古土壤的粒度组成特征进行了系统的研究。结果表明，绰墩古土壤〈5μm粘粒、5～10μm细粉砂和10～50μm粗粉砂组分平均含量分别为22．89％、22．96％63．52％，其中10～50μm粗粉砂组分为众数粒组。〉50μm砂粒平均含量仅为5．10％。绰墩古土壤粒度组成与镇江下蜀黄土粒度组成具高度相关性（r=0．97）。根据粒度分析，我们初步认定绰墩古土壤母质为下蜀黄土。

The origin of Chuodun paleosel in Kunshan was elucidated by particle size distributions. Results showed that the Chuodun paleosol mainly consists of fine particle less than 50 μm. The ＂second large particle componen＂ of the Chuodun paleosol is those particles between 10μm and 50μm, accounting for 46.47% to 63.52% respectively, with the average content of 56.32%. The particle size analyses indicate that the grain size composition of the Chuodun paleosel is well correlated with that of the Xiashu loess in Zhenjiang. Hence, it ean be deduced that the parent material of the Chuodun paleosol might have been from eolian Xiashu loess.