贵东岩体X荧光光谱、等离子体质谱分析结果及其对岩体演化的指示意义  

Analysis of X-Ray Fluorescence Spectroscopy and Plasma Mass Spectrometry of the Guidong Granite Body and Its Implications to Granite Evolution

作　　者：李宏卫[1,2] 陈国能[1] 彭卓伦[1] 

机构地区：[1]中山大学地球科学系,广东广州510275 [2]广东省地质调查院,广东广州510080

出　　处：《光谱学与光谱分析》2013年第7期1965-1968,共4页Spectroscopy and Spectral Analysis

基　　金：高等院校博士点基金项目(2008321104111260);广东省重点基金项目(10251027501000019)资助

摘　　要：粤北贵东岩体是由形成于早侏罗世(燕山一期)的粗粒黑云母花岗岩、晚侏罗世(燕山三期)的中细粒二云母或白云母花岗岩、早白垩世(燕山四期)石英正长岩组成的复式岩体。不同期次花岗岩进行X荧光光谱和等离子体质谱测试结果显示:(1)同期岩体自上而下具有硅碱组分降低,铁镁含量组分和LREE,LREE/HREE及(La/Yb),N值总体升高的变化趋势;(2)复式岩体从早期到晚期,岩体的硅碱组分逐渐升高,而∑REE,LREE/HREE,(La/Yb)N及δEu值则逐渐降低,稀土配分曲线由右倾型向海鸥型过渡,表明复式岩体的形成是地壳岩石多次原地熔融(重熔)的结果;(3)微量元素组成同样反映复式岩体形成是地壳岩石多次原地熔融(重熔)的结果;多次熔融(重熔)导致晚期岩体U丰度和U/Th比值升高,故该区铀矿床的形成多与燕山晚期的熔融(重熔)事件有关。The Guidong composite granite body （CGB） located in the north Guangdong Province consists of numerous rock bodies formed respectively in the early and late Jurassic and early Cretaceous. Analysis of the granites of different perod with X- ray fluorescence spectroscopy and plasma mass spectrometry indicates： （1） From the top of a granite body downwards, the felsic components of rock decrease, while the mafic and 1REE, LREE/HREE, （La/Yb）N, as well as · Eu value increase, suggesting the material differentiation in the in-situ melting of crustal rocks and crystallisation of magma; （2） From old to young of the dif- ferent period granite-massifs in the Guidong CGB, the felsic compositions totally decrease, and the mafic components, ~REE, LREE/HREE, （La/Yb）N, and Eu value increase as well, implying multiple crustal melting （remelting） events in the Mesozoic in this area; and （3） Primitive mantle-normalized spider diagram for trace elements of Guidong CGB suggests high maturity of the crust involved in the in-situ melting.

关 键 词：X荧光光谱 等离子体质谱 贵东岩体 原地重熔 

分 类 号：P581[天文地球—岩石学]