内蒙古塔尔气地区中酸性脉岩的地球化学特征及成因  

Geochemical characteristics and petrogenesis of intermediate-acidic dykes in Taerqi,Inner Mongolia

作　　者：汪爱鸿 张春蕾 和钟铧[1] 隋振民[1] 马瑞[1] 杨德明[1] 

机构地区：[1]吉林大学地球科学学院,长春130061 [2]辽宁省地质矿产调查院,沈阳110032

出　　处：《世界地质》2016年第2期403-417,共15页World Geology

基　　金：中国地质调查局区域地质调查项目(1212011120672)

摘　　要：对塔尔气地区中酸性脉岩的地质特征、锆石U-Pb年龄及地球化学特征进行了研究,并讨论了该地区中酸性脉岩的形成时代、成因及构造环境。锆石U-Pb测年结果表明,这些中酸性脉岩形成于早白垩世141.4~136.0 Ma和136.5~126.4 Ma两个阶段。其中中性脉岩具有中硅、富碱、准铝质（A/CNK=0.80~0.92）的特点,属于高钾钙碱性准铝质岩石,无Eu负异常;而酸性脉岩则表现出高硅、富碱、弱过铝质（A/CNK=1.03~1.24）的特点,属于高钾钙碱性系列,大多具有明显的Eu负异常。综合区域地质资料分析,塔尔气地区中性脉岩与酸性脉岩可能为两次岩浆事件的产物,形成于伸展构造环境。The authors explored the age,petrogenesis and tectonic setting of intermediate-acidic dykes in Taerqi regions through the study in geological fieldwork,zircon U-Pb age and geochemical features of them. The zircon U-Pb age indicates that the intermediate dykes and acidic dykes were formed in Early Cretaceous including 141. 4~ 136. 0 Ma and 136. 5 ~ 126. 4 Ma,respectively. The geochemical data show that the intermediate dykes are characterized by medium silicon,alkali-rich,quasi-aluminous（ A / CNK = 0. 8 ~ 0. 92）,belonging to high-K calcalkaline weakly quasi-aluminous series,and most of them are obvious in having Eu negative anomaly. The acidic dykes are characterized by high silicon,alkali-rich,weakly peraluminous（ A / CNK = 1. 03 ~ 1. 24）,indicating high-K calc-alkaline series and most of them have no Eu negative anomaly. Based on a synthesis of petrography,geochronology,elemental and isotopic geochemistry,it is suggested that the intermediate dykes and acid dykes in Taerqi may be products of two stages of magmatic event under a extensional setting.

关 键 词：内蒙古 塔尔气 中酸性脉岩 锆石U-PB年龄 成因 

分 类 号：P595[天文地球—地球化学] P597[天文地球—地质学]