内蒙古东乌旗沟特岩体年代学、地球化学及铪同位素特征及其地质意义  

Zircon U-Pb Geochemistry,Geochronology and Hf Isotope of the Goute Granite Pluton,East Wuzhu Muqinqi,Inner Mongolia,and Their Geological Significance

作　　者：熊光强[1,2] 赵洪涛[1] 刘敏[1] 张达[1] 秦晓峰[1] 王忠 仝立华[4] 胡兆初[5] 

机构地区：[1]中国地质大学(北京)地球科学与资源学院,北京100083 [2]江西省地矿局物化探大队,南昌330002 [3]内蒙古地质调查院,呼和浩特010020 [4]中国地质调查局油气资源中心,北京100029 [5]中国地质大学(武汉)地质过程与矿产资源国家重点实验室,武汉430074

出　　处：《矿物岩石地球化学通报》2014年第4期439-451,共13页Bulletin of Mineralogy, Petrology and Geochemistry

基　　金：中国地质调查局地质调查项目(1212011085490)

摘　　要：对沟特岩体开展了地球化学、年代学及Hf同位素特征等研究.结果显示沟特花岗岩SiO2含量为76.41％～78.36％,AI2 O3为11.72％～12.86％,A/CNK值为1.40～1.43,K2O＋Na2O为7.99 ％～8.05％,K2O为4.8％～5.04％,Na2O为3.18％～3.47％,Na2 O/K2O为0.66～0.72,属高钾钙碱性系列,里特曼组合指数σ值为1.81～2.24,碱度率AR为4.67～4.97,也表明该岩体属钙碱性系列;在微量元素方面,沟特花岗岩体富集大离子亲石元素和Pb,明显亏损高场强元素;沟特花岗岩的REE总量为115.84×10-6～153.56×10-6,LREE/HREE为7.75～9.27,具有明显的轻稀土富集,重稀土亏损特征,（La/Yb）N值为5.24～7.73,δEu为0.27～0.35,Eu负异常;锆石U-Pb年龄为134.1±1.0 Ma,属早白垩世;Hf同位素特征表明该区花岗岩的形成可能与早期的板块俯冲作用有关.上诉特征表明沟特花岗岩是在伸展背景下形成的受俯冲组分影响而形成的壳幔混合型高分异S型花岗岩,属于燕山造山旋回的晚期.This paper carried out researches mainly about geochemistry, isotope chronology and Hf characteristics of the Goute pluton. The contents of SiO2 and Al2O3 respectively are 76.41%-78.36% and 11.72%-12.86%, and the A/CNK ratio is 1.40-1.43 indicated that the pluton is peraluminous; the contents of K2O and Na2O respec- tively are 4.8%-5.04% and 3.18%-3.47%, The values of K2O＋Na2O and Na2O/K2O respectively are 7.99%-8.05 % and 0. 66-0. 72, indicating the Goute granite is higher in potassium calc-alkaline; the values of σand AR are 1.81-2.24 and 4.67-4.97, respectivley, also reflects that the Goute granite is calc-alkaline. The results of trace elements showed that the Goute granite enriches in LILEs and Pb, but strongly depletes in HFSEs. The ∑REE is between 115.84 X×10-6 to 153.56 × 10-6 , LREE/HREE is 7.75-9.27, normalized La/Yb ratio is of 5.27-7.73 and δEu is 0. 27-0. 35. The intrusion is characterized remarkably by enriching LREE and depleting HREE. The zircon U-Pb age of the Goute granite is 134.1-1.0 Ma, belonging to the early Cretaceous; Hf isotope data suggested that the formation of its mantle source may be associated with early plate subduction. These charac-teristics indicated the Goute granite was a highly differentiated crust-mantle mixed S-type granite which was formed in the late of the Yanshan orogenic cycle.

关 键 词：内蒙古 沟特岩体 早白垩世 构造体制转换 

分 类 号：P597[天文地球—地球化学]