桂岭岩体稀土、微量元素地球化学特征研究

Geochemical characteristics of rare earth elements and trace elements of Guiling rock mass

文章运用岩石地球化学方法,对桂岭岩体的构造环境和地球化学特征进行了研究,结果显示:桂岭岩体岩石平均LREE/HREE=7.68,(La/Yb)N=6.77,(La/Sm)N=4.65,(Gd/Yb)N=1.04,平均δEu=0.45<1,表明轻重稀土轻度分异,轻稀土相对富集,轻稀土内部分馏明显,存在负铕异常;岩体明显亏损Nb、Sr、Ti,显示桂岭岩体的源区可能主要来自地壳,是地壳环境下壳源岩石发生部分熔融的产物;研究表明,桂岭岩体形成于挤压—伸展的大地构造环境。

This paper makes research on tectonic setting and geochemical characteristics of Guiling rock mass by using methods of lithogeochemistry. Results reflect that： average LREE/HREE= 7. 68, （La/Yb）N （La/Sm） N = 4.65, （Gd/Yb）N = 1.04, and average δEu = 0. 45〈1. It is suggested that the heavy rare earths are differentiated from each other mildly, and the light rare earths enrich relative =6. 77, ight and y. Inner fractionation exists obviously in the light rare earth, and negative Eu anomalies occur. In the rock mass de pletion of Nb, Sr and Ti exists, and it is suggested that the source of Guiling rock mass originates from earth ＇s crust, and it is a product of partially melted lower crust rocks in the environment of crust. Research shows that the rock formed ill the compression-stretch geotectonic environment.