桂东北海洋山岩体锆石SHRIMP U-Pb定年和地球化学研究  

Zircon SHRIMP U-Pb Dating and Geochemical characteristics of Haiyangshan Monzogranitic Batholith,Northeast Guangxi

作　　者：程顺波 付建明 陈希清 马丽艳 卢友月 

机构地区：[1]武汉地质调查中心,武汉430205

出　　处：《华南地质与矿产》2012年第2期132-140,共9页Geology and Mineral Resources of South China

基　　金：中国地质调查局地质大调查项目(编号:1212010533307和1212010813061)

摘　　要：桂东北海洋山岩体为岩性单一的二长花岗岩岩基。锆石SHRIMP U-Pb定年显示海洋山岩体主结晶年龄为431±7 Ma(MSWD=3.14),与赣湘桂内陆加里东期花岗闪长岩-二长花岗岩形成时代相似,为同一期成岩事件的产物。元素地球化学研究表明,绝大多数样品具有富硅(～68%),富钾(K2O/Na2O>1.5),弱过铝质(A/CNK均值1.05)和低Al2O3/TiO2值(<100)、高CaO/Na2O值(>0.3)的特征。与临区浅变质基底一致的εNd(t)值(-8.0～-8.6)和T2DM值(1.82～1.87 Ga),指示其理想源区为成熟度较低的古老变质杂砂岩。进一步的宏观地质特征和华南加里东造山带构造演化序列分析表明,海洋山岩体属于陆壳改造型花岗岩,其形成的构造环境很可能为汇聚造山向非造山转化的后造山伸张环境。Haiyangshan granite is a monzogranitic batholith in northeast Guangxi province.Zircon SHRIMP U-Pb dating of this granite yields an age of 431±7 Ma（MSWD=3.14）,same as granodioritic-monzogranitic plutons of inland area like Jiangxi,Hunan and Guangxi,providing temporal constraint of a diagenesis event in late Caledonian.Major,trace elements and Nd isotopic compositions of several rock samples are reported to constraints its magma source and geodynamic setting in northeast Guangxi province.The geochemical of those samples,which behavior as relatively low SiO2 contents（0.3） ratios,with low εNd（t）（-8.0～-8.6）and relatively high T2DM values（1.82～1.87 Ga）,indicating they are originated from the salic crust with metamorphosed graywacks as its major composition.Integrated with its geological feature and evolution of Caledonian orogen of Southeast China,we advocate that Haiyangshan batholith belongs to continental crust-transformation series and it forms in late orogeny setting between orogenic convergence and anorogenic periods.

关 键 词：SHRIMP锆石年龄 地球化学 加里东期 海洋山岩体 桂东北 

分 类 号：P595[天文地球—地球化学] P597[天文地球—地质学]