西秦岭秦岭梁环斑花岗岩锆石U-Pb年龄及地球化学特征  

Zircon U-Pb age and geochemical characteristics of Qinlingliang rapakiwi granite from Western Qinling orogenic belt in Shaanxi

作　　者：陈清敏 郭岐明 王强 王喆 高勇浩 CHEN Qingmin;GUO Qiming;WANG Qiang;WANG Zhe;GAO Yonghao(Shaanxi Geological Survey Experiment Center,Shaanxi Institute of Geological Survey,Xi’an 710054,Shaanxi,China;The Silk Road Academy of Geological Science,Xi'an 710054,Shaanxi,China;Shaanxi Mineral Resources and Geological Survey,Shaanxi Institute of Geological Survey,Xi'an 710068,Shaanxi,China)

机构地区：[1]陕西省地质调查院/陕西省地质调查实验中心,陕西西安710054 [2]丝绸之路地质科学院,陕西西安710054 [3]陕西省地质调查院/陕西省矿产地质调查中心,陕西西安710068

出　　处：《地质通报》2019年第2期213-222,共10页Geological Bulletin of China

基　　金：陕西省公益性地勘专项项目<陕西秦岭造山带中生代构造体制与成矿作用研究>(编号:20130301)

摘　　要：对秦岭梁岩体进行了地质学、岩石学、地球化学及年代学研究。秦岭梁岩体主要岩石类型有似斑状黑云环斑花岗岩、似斑状角闪黑云环斑花岗岩、中粒黑云二长花岗岩,普遍发育环斑结构,LA-ICP-MS锆石U-Pb测年结果为215.1±2.5Ma(MSWD=0.29,n=17),显示秦岭梁环斑花岗岩形成于晚三叠世。秦岭梁环斑花岗岩属于高钾钙碱性系列,具有准铝质-弱过铝质的特点,富集Rb、Th、K、Pb、Nd等,贫Ba、Nb、Ta、La、P、Eu等,明显亏损Nb、Ta、P。稀土元素含量中等偏低,轻、重稀土元素分异程度高,稀土元素标准化配分曲线呈明显的右倾模式。秦岭梁环斑花岗岩岩浆主要来源于地壳熔融,同时具有壳幔混合特点。结合区域地质背景,认为秦岭梁环斑花岗岩形成于造山后伸展环境。Based on geological,petrological and geochemical studies,the authors investigated Qinlingliang rapakiwi granite intrusion,porphyritic biotite rapakivi granite,porphyritic hornblende biotite rapakivi granite and medium-grained biotite monzonitic granite.LA-ICP-MS zircon U-Pb analysis suggests that Qinlingliang rapakiwi granite intrusion was formed in late Triassic(215.1±2.5Ma).Qinlingliang rapakiwi granite belongs to high-K calc-alkaline series with aluminous-peraluminous nature,and is characterized by enrichment of Rb,Th,K,Pb and Nd,depletion of Ba,Nb,Ta,La,P and Eu,and significant loss of Nb,Ta and P.In addition,this intrusion has moderate-low REE concentration and right-inclined distribution curve.The magma probably mainly originated from partial melting of the crust,and also had the characteristics of crust-mantle mixing.In combination with regional geological background,the authors hold that Qinlingliang rapakiwi granite intrusion probably originated from a post orogenic extension environment.

关 键 词：西秦岭 秦岭梁环斑花岗岩 地球化学 LA-ICP-MS锆石U-PB测年 

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