洪积扇上全新世古土壤的特点及环境意义——以临汾盆地东坡沟剖面为例

Characteristic of Paleosol on the Paleo-alluvial-pluvial Fans and Its Environmental Significance

通过对山西襄汾东坡沟全新世黄土剖面地层学和土壤学的研究 ,以及碳酸钙、铁和粒度的测定 ,发现全新世古土壤中碳酸钙经历了明显的淋溶与淀积 ,古土壤上部CaCO3 平均含量 10 .5 8% ,下部为 18.4 7% ,CaCO3 结核的淀积深度约为 1.1m ,铁在古土壤顶部有微弱的淋移和富集 ,粘化作用不明显。成壤作用始于全新世大暖期之初 ,较为强烈的成壤作用发生于大暖期的晚期 (4 10 0aB .P～ 310 0aB .P) ,这一阶段土壤湿度大 ,气候波动小 ,CaCO3 淋溶较强。大暖期结束后 ,冬季风在黄土高原占主导地位 ,土壤的淋溶作用和粘土作用均有一定程度减弱 ,显示气候干旱的趋势。该剖面位于古山前洪积扇前端 ,地形较高 ,降水易分散 ,淋溶作用总的说来不强烈 ,土壤上部CaCO3 残留较多 ,CaCO3淀积深度较浅 ,土壤类型接近黑垆土。

Pedological and stratigraphic observations indicate that there is one paleosol layer on the Holocene loess profile in DPG site,Co. Xiangfen of Shanxi province. CaCO 3 , TFe and clay analysis prove that pedological process started at the beginning of the Holocene Magathermal. The major pedological process developed between 4450～3100aB.P, when climate was humid and stable, ancient people cultivated here and created the splendid culture of Taosi . The leaching of CaCO 3 existed during the pedological process . The illuvial depth of CaCO 3 is about 1.1m . The pedogenesis is not intense overall due to deep slope on palaeo-alluvial-pluvial fans. The type of paleosol here can be regarded as the one of Heilutu soil.