湖南澧阳平原玉成土壤剖面粒度组成及其环境意义

Grain-size Characteristics of Yu Cheng Soil Profile and Its Environmental Significance in the Liyang Plain,Hunan

通过对澧阳平原大量的野外考察、典型剖面玉成(YC)土壤剖面的系统采样和室内粒度分析和年代学分析,探讨了YC土壤剖面的粒度特征,揭示了澧阳平原末次冰期至全新世早期环境演变过程。研究结果表明,澧阳平原YC土壤剖面沉积物粒度无砾石,野外调查发现土壤剖面无明显层理,沉积物主要以粉砂为主,属于典型风尘沉积物特征,非水流沉积物。澧阳平原YC土壤剖面沉积物粒度经历了粗-变细-细-粗-细的变化过程,表明澧阳平原YC土壤剖面记录了末次冰期至全新世早期环境经历了5次明显变化,大致为56.0kaBP～31.8kaBP为相对寒冷干旱,31.8kaBP～23.6kaBP气候转型阶段,23.8kaBP～14.8kaBP为相对冷湿,14.8kaBP～10.6kaBP位于晚冰期阶段,气候变化剧烈,10.6kaBP～6.96kaBP为全新世早期,气候向暖湿转变。

According to field investigation,sample and grain-size analysis,optically stimulated luminescence （OSL） and AMS 14 C dating in Yu Cheng soil profile in Liyang plain,Hunan.The characteristics of sediments in YC soil profile and the environmental change were discussed from last glacial to earlier Holocene.The results showed that sediments of YC soil profile was the eolian deposits and not fluvial sediments based on the grain size and other characteristics.The changing process of particles of coarse-becoming fine-fine-coarse-fine of YC soil profile has been found,which shows sediments of YC soil profile have well recorded the climatic environmental change during 56.00 ka BP-6.96 ka BP in Liyang plain.Five stages of climatic change could be found in Liyang plain.Five stages of climate change were following：cold and dry period（56.00 ka BP-31.80 ka BP）,relative warm and wet period （31.80 ka BP-23.80 ka BP）,cold and wet period （23.80 ka BP-14.80 ka BP）,intensively change period（14.80ka BP-10.60 ka BP and warm and wet period（10.60 ka BP-6.96 ka BP）.