武汉第四纪网纹红土的稀土元素特征及其物源指示意义

REE Characteristics of Vermicular Red Clay of the Quaternary Period from Wuhan,Hubei Province,Chinaand Its Implications

对武汉地区第四纪中更新世王家店组(Qp2w)网纹红土采用ICP-MS进行了稀土元素质量分数测定,分析了稀土元素组成与分馏特征,并与渭南黄土和长江沉积物进行了对比。分析表明,Qp2w网纹红土的REE含量除了受沉积物粒度控制之外,还受风化淋溶作用控制。Qp2w网纹红土的Eu负异常,与渭南黄土相比未出现明显的再分馏;Ce异常出现分层现象,分馏复杂;轻重稀土元素分馏比渭南黄土略弱,比长江沉积物弱得多;轻稀土元素分馏比渭南黄土和长江沉积物显著;重稀土元素分馏较渭南黄土和长江沉积物要弱。总体上,Qp2w网纹红土稀土配分模式与渭南黄土更相似。通过物源计算,总结出Qp2w网纹红土具有风积成因的特点,这表明其有可能是黄土高原黄土朝南或东南方向的延伸。

The rare earth element contents of 9vermicular red clay samples of the Quaternary period and the middle Pleistocene epoch and the Wangjiadian formation（Qp2w）in Wuhan,the capital of Hubei Province,China were analyzed by ICP-MS.Results show that∑REE of Qp2 wvermicular red clay is controlled by,beside grain size of sediment,weathering-eluviating.The Europium（Eu）of Qp2 wvermicular red clay is negative anomaly.Compared with the Weinan loess,its Eu fractionation is not apparent.The cerium（Ce）fractionation presents layering and it is remarkable during weathering.It shows fractionations between LREEs and HREEs,and those between HREEs of Qp2 wvermicular red clay are weaker than Weinan loess and the Yangtze River,but fractionation between LREEs are just the opposite.To sum up,the rare earth distribution patterns of Qp2 w vermicular red clay are very similar with Weinan loess.Through the provenance calculation,the data show that Qp2 wvermicular red clay is similar to the sediment of aeolian deposit,probably implicating that Qp2 wvermicular red clay is the aeolian deposit extended toward the southern or southeastern area beyond the Loess Plateau.