通过对长安少陵塬双竹村S4古土壤的野外观察、元素分析及粒度分析,讨论其环境变化。结果表明:(1) 根据剖面特点、元素淋溶迁移特征及脱离粘化层的钙淀积层,可判断S4属于酸性淋溶土,其剖面构型为Bts-Bs-BC-Bck-C;(2) 根据S4的颜色、质地、结构及铁质胶膜和钙淀积层的特点,但又不具明显的铁铝化特征,可判断S4可能相当于现今中国北亚热带的黄棕壤;(3)根据CaCO3迁移深度、风化淋滤黄土层厚度及红色铁质粘土胶膜的最大深度与江苏六合地区现代黄棕壤的剖面很相似,可判断当时西安地区的年均温、年均降水量与六合地区较接近。
Based on field investigation, geochemistry and grain size analyses on the fourth paleosol (S4) at Shaolingyuan section in Chang’an County, we concluded the following new comings about weathering features and the environmental changes. (1) The soil microstructure and leaching and immigration of elements indicate S4 at this section belong to acid leached soil type, and the profile structure is Bts-Bs-BC-Bck-C.(2) The color, structure, clayey films illuvial without obvious ferrallitisation characteristics show that the S4 is equivalent to yellow-brown soil developed at modern subtropics. (3) By contrasting the section between the S4 and the modern yellow-brown soil, illuvial depth of calcium carbonate and the thickness of weathering are similar to the yellow-brown soil in Liuhe, Jiangsu. Therefore we estimate the S4 formed at a mean annual precipitation and temperature equivalent to Liuhe area.
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