【摘要】 中国贵州、云南和广西交界处存在大面积以宣威地区为中心的土壤稀土元素地球化学异常,为了探究该地区土壤稀土元素来源,本研究采集了宣威地区土壤(红土)和岩石(玄武岩、白云岩、灰岩、砂岩、粉砂岩、泥岩、凝灰岩和页岩)样品,分析了稀土元素、微量元素、pH值和有机质组成。结果显示:土壤稀土元素含量均在大陆上地壳的2倍左右,玄武岩稀土元素含量与上覆土壤一致,但沉积岩(白云岩、石灰岩和砂岩)稀土元素含量远低于上覆土壤。土壤稀土元素与基性岩中富集的元素Co、Ni、Cu、Zn和Au等具有极好的相关性(相关系数r>0.7),但与pH值(r=0.33)和有机质含量(r=0.20)无明显相关关系。玄武岩与其上覆土壤之间的稀土配分模式具有高度的一致性,而沉积岩与其上覆土壤之间的稀土配分模式差异较大,且所有土壤中位值的稀土配分模式与玄武岩的极其相似。宣威地区处于既有玄武岩又有海相沉积岩出露的区域,玄武岩可能是该地区土壤稀土元素的主要来源。更多还原

【Abstract】 There is a large REE soil geochemical anomaly, which is centered in the Xuanwei area, in the conjunction area of Guizhou, Yunnan, and Guangxi provinces, China. In this study, soil(red clay) and various kinds of rocks(basalt, dolomite, limestone, sandstone, siltstone, mudstone, tuff, and shale) in the Xuanwei area have been collected for analyzing contents of the REE and trace elements, and organic matter(Corg) composition, and measuring pH values in order to explore the REE source of soils in the area. The results show that the REE content of soils are about two times higher than that of the upper continental crust. The REE contents of basalt samples are consistent with those of the overlying soils, but the REE contents of sedimentary rocks(dolomite, limestone, and sandstone)are far below those of the overlying soils. The REE contents of the soil samples have excellent correlation(r > 0.7)with their contents of Co, Ni, Cu, Zn, and Au, which are normally rich in basic rocks, but have no obvious correlations with pH values(r=0.33) and organic matter contents(r=0.20). The REE distribution patterns of basalts are highly consistent with those of the overlying soils, while REE patterns of sedimentary rocks are quite different to those of the overlying soils. In addition, the REE pattern of median values of all soil samples is exactly similar with that of the basalt. Although basalt and marine sedimentary rocks are both exposed in the Xuanwei area, the basalt may be the main source of REE in soil samples in the REE geochemical anomaly area.更多还原