北秦岭西段奥陶纪红花铺岩体岩石地球化学特征及地质意义  

Geochemical characteristics of Ordovician Honghuapu intrusions in the west segment of North Qinling Mountains and their geological significance

作　　者：董增产[1] 王洪亮[2] 郭彩莲[1] 徐学义[2] 陈隽璐[2] 何世平[2] 

机构地区：[1]西北大学大陆动力学国家重点实验室 西北大学地质系,陕西西安710069 [2]西安地质矿产研究所,陕西西安710054

出　　处：《岩石矿物学杂志》2009年第2期109-117,共9页Acta Petrologica et Mineralogica

基　　金：国家自然科学基金资助项目(40773044,40472044);国土资源大调查项目(1212010610319);国家科技支撑计划项目(2006BAB01A11);西北大学大陆动力学国家重点实验室开放课题基金(06LCD16)

摘　　要：红花铺岩体位于北秦岭造山带西段,侵位于奥陶纪草滩沟群之中,岩石类型主要为中细粒奥长花岗岩。岩石地球化学分析结果表明该岩体属弱过铝质钙碱性岩石系列,为I型花岗岩;轻重稀土元素分馏不明显,轻稀土元素略为富集,稀土元素球粒陨石标准化配分型式为右倾型,Eu异常不明显;主量、微量及稀土元素等相关的构造环境判别结果均显示其具典型的火山弧花岗岩特征,结合区域上与一套岛弧型火山岩(草滩沟群)共生的特点,分析红花铺岩体形成于俯冲带的岛弧环境。红花铺岩体已获得(450.5±1.8)Ma的单颗粒锆石U-Pb侵位年龄,属晚奥陶世,揭示北秦岭西段加里东期存在板块俯冲作用。The Honghuapu intrusions, located in the western segment of northem Qinling orogenic belt and intruding into Ordovician Caotangou Formation, are medium-fine grained trondhjemites. Geochemical studies indicate that they are weakly peraluminous calc-alkaline rocks and can be classified as I type granite. Light REE elements are rich, and light and heavy REE are not significantly fraetionated. In chondrite-normalized REE diagrams, all samples are LREE-enriehed with insignificant Eu anomalies. Their major and trace element geochemical characteristics are all comparable with features of typical volcanic-arc granites. It is thus concluded that the Honghuapu intrusions were formed in island arc settings. The Honghuapu intrusions were dated at （450.5 ± 1.8 ） Ma by the LAICPMS U-Pb zircon method. The new geochemical dating has important significance to the study of Early Paleozoic tectonic evolution and dynamic mechanism of Qinling orogenic belt.

关 键 词：北秦岭 红花铺侵入体 地球化学特征 构造意义 

分 类 号：P588.121[天文地球—岩石学] P595[天文地球—地质学]