环洞庭湖地区网纹红土中稀土元素的地球化学特征

RARE EARTH ELEMENT GEOCHEMISTRY OF RETICULATE RED CLAY AROUND DONGTING LAKE

对环洞庭湖地区网纹红土中稀土元素(REE)进行分析,结果表明,同一剖面稀土元素的总量(ΣREE)表现为白色网纹明显高于红色基质,白色网纹ΣREE平均值为224.7μg·g-1,红色基质平均值为198.5μg·g-1,总平均值为211.6μg·g-1,明显高于镇江下蜀黄土(207.7μg·g-1)和黄土高原黄土(159.2μg·g-1),表明网纹红土经过了强风化成壤作用.而且,网纹红土与黄土高原黄土和镇江下蜀黄土的稀土配分模式具有相似性,表明网纹红土在成因上与黄土高原黄土和镇江下蜀黄土具有一致性,同为风成成因,网纹红土可能是黄土高原黄土在中国东南部或南部的延伸.

The characteristics of the rare earth elemen （REE） geochemistry of reticulate red clay around Dongting lake were discussed. The results showed a higher EREE contents in the white reticulate clay than in the red clay, the mean REE contents is 224. 7μg·g^-1 in the white reticulate clay, and 198.5μg·g^-1 in the red clay. The mean REE contents of all samples from the reticulate red clay is 211.6μg·g^-1, which is the highest comparing to the Xiashu loess（207.7μg·g^-1）in Zhenjiang and the loess in the Loess Plateau （159.2 μg·g^-1）, which indicated that the reticulate red clay had been experienced a intensively pedogenic process. The REE distribution patterns and characteristic parameters are similar between the white reticulate clay and the red clay, and also the REE distribution patterns of the reticulate red clay is similar with of Xiashu loess in Zhenjiang province and of loess in the loess Plateau, which may display a similar formation process between the three clayey silt sediments. It may implicate that the reticulate red clay is the aeolian deposits extended toward the southern or southeastern area beyond the Loess Plateau.