河北平原区泥岩的稀土元素地球化学特征
Distribution characteristic of rare earth elements of mudstone of Hebei plain area
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摘要: 为了查明河北平原区二叠纪泥岩中稀土元素的特征、来源及其地质意义,应用电感耦合等离子体质谱法(ICP-MS)对河北平原区32个泥岩样品的稀土及微量元素进行测试,全面分析了稀土元素、地球化学参数、空间分布规律及分布模式。研究表明:河北平原区泥岩稀土元素相对富集,太原组泥岩中的稀土元素明显低于山西组;稀土元素与Be,Sc,Ti,V,Co,Zn,Nb,Th,Hf,Ta等亲石元素相关性好,反映了研究区泥岩稀土元素主要来自于陆源碎屑;沉积速率、稀土元素及微量元素比值(∑REE,(La/Yb)_N,La/Sm等)在太原组-山西组分界层面上存在较明显的突变现象,是太原组沉积后华北板块构造抬升的直接反映。Abstract: The abundances of rare earth element ( REE) in 32 mudstone samples from Hebei plain area were deter- mined by inductively couple-plasma mass spectrometry (ICP-MS). The contents of the REE,geochemical parameters, geological significance,spatial distribution and distribution patterns were studied in this paper. The results are as fol- lows:compared with North American shale,the REE are obvious in the study area,and the REE content in the Shanxi Formation are higher than in the Taiyuan Formation. The correlation between ΣREE and external elements,like Ti,Ni, Pb,Rb,Ga,Cr and Zn is very good,which indicates that the REE is mainly supplied by terrigenous minerals. The de- positing rate,rare earth element and trace element ratios have obvious variation at sedimentary interface between the Taiyuan Formation and the Shanxi Formation,respectively,reflecting tectonic uplift in Huabei plain area.
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