内蒙古阿巴嘎旗阿德拉嘎碱长花岗岩锆石LA-ICP-MS U-Pb年龄、地球化学特征及构造意义  

Zircon LA-ICP-MS U-Pb age,geochemical character of Adelaga alkali-feldspar granite,in Abaga Banner,Inner Mongolia,and tectonic significance

作　　者：赵泽南 魏民 杨建坤 倪克庆 张建珍 申晋青 刘腾飞 葛斌 ZHAO Zenan;WEI Min;YANG Jiankun;NI Keqing;ZHANG Jianzhen;SHEN Jinqing;LIU Tengfei;GE Bin(Hebei regional geological survey institute,Langfang,Hebei,065000)

机构地区：[1]河北省区域地质调查院,河北廊坊065000

出　　处：《地质论评》2023年第2期779-794,共16页Geological Review

基　　金：中国地质调查局“内蒙古翁根温多尔等八幅1∶5万矿产调查项目”(编号:1212011220451)的成果。

摘　　要：阿巴嘎旗阿德拉嘎碱长花岗岩位于贺根山蛇绿岩带北侧。为了确定该碱长花岗岩体的岩石成因类型,探讨其构造环境,对该岩体进行了野外地质、岩石学、地球化学和LA-ICP-MS锆石U-Pb年代学研究。锆石LA-ICP-MS U-Pb测年表明,阿德拉嘎碱长花岗岩体的侵位年龄为310.7±2.6 Ma,形成时代为晚石炭世。岩石地球化学研究表明,阿德拉嘎碱长花岗岩具有较高的SiO_(2)、Na_(2)O+K_(2)O含量和较高的Ga/Al、(Na_(2)O+K_(2)O)/CaO值,相对贫CaO、MgO、Sr、Ba、Eu、Ti和P。稀土元素总量较低,轻重稀土分馏不明显,稀土配分曲线呈海鸥性,负铕异常明显(δEu=0.15~0.37)。岩石学和岩石地球化学特征表明,该碱长花岗岩为A型花岗岩,形成于弧后伸展构造环境,为晚石炭世古亚洲洋向西伯利亚俯冲作用的产物。Objectives:This paper provided petrography,geochemical characteristics,LA-ICP-MS zircon U-Pb age of Adelaga alkali feldspar granite,in Abaga Banner,Inner Mongolia.The formation age,genesis and tectonic significance of granits are discussed.Methods:Based on the field work,through the microscopic observation,the whole rock chemical analysis,the LA-ICP-MS zircon U-Pb isotopic chronology of granites.Results:The Zircon LA-ICP-MS U-Pb ages indicates that the Adelaga alkali feldspar granite is 310.7±2.6 Ma,and formed in Upper Carboniferous.The granite has the character of Higher content of SiO_(2),Na_(2)O +K_(2)O,higher ratio of Ga/Al,( Na_(2)O+K_(2)O)/Ca O,and relatively poor Ca O,Mg O,Sr,Ba,Eu,Ti and P.The total amount of rare earth elements is low,the fractionatio of light and heavy rare elements is not aobious,the distribution curve of rare eatrh is seagull,and the anomaly of negative europium is obvious( δEu = 0.15 ~ 0.37).The granite belong to A-type granite.Conclusions:The Adelaga alkali feldspar granite is A-type granite,and formed in back-arc extensional tectonic setting of Upper Carboniferous,which is the product of Paleo-Asian Oceanic subduction to Siberia.

关 键 词：碱长花岗岩 A型花岗岩 锆石U-PB定年 晚石炭世 弧后伸展环境 内蒙古阿巴嘎旗 

分 类 号：P597.3[天文地球—地球化学] P588.121[天文地球—地质学]