丁启福,黄增保.北祁连中段毛藏寺花岗闪长岩U-Pb年龄及岩石地球化学特征[J].西北地质,2019,52(4):53-62 DING Qifu,HUANG Zengbao.U-Pb Ages and Geochemistry of Maozangsi Granodiorite in North Qilian Mountains, China[J].Northwestern Geology,2019,52(4):53-62
北祁连中段毛藏寺花岗闪长岩U-Pb年龄及岩石地球化学特征
U-Pb Ages and Geochemistry of Maozangsi Granodiorite in North Qilian Mountains, China
投稿时间:2019-07-12  修订日期:2019-08-22
DOI:
中文关键词:  岩石成因;花岗闪长岩;构造意义;北祁连山
英文关键词:Petrogenesis;granodiorite;tectonic implications;North Qilian orogen belt
基金项目:中国地质调查局“中国矿产地质与成矿规律综合集成和服务(矿产地质志)”项目(DD20160346)
作者单位
丁启福 甘肃矿业开发研究院, 甘肃 兰州 730000 
黄增保 甘肃省地质调查院, 甘肃 兰州 730000 
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中文摘要:
      笔者研究了北祁连中段毛藏寺花岗闪长岩体的岩石学、年代学和地球化学特征。毛藏寺岩体主要岩石类型为花岗闪长岩,锆石SHRIMP U-Pb测年获得花岗闪长岩结晶年龄为(456±3)Ma。花岗闪长岩的SiO2含量较高,介于65.1%~73.0%,较低的Mg#值(18~32),K2O/Na2O介于0.82~1.37,A/NKC=0.9~1.1,总体为高钾钙碱性准铝质花岗岩;岩石微量元素组成具富集LILE元素,亏损HFSE元素,轻重稀土分异明显[(La/Yb)N=11.1~34.1],具弱负Eu异常。综合地球化学特征和区域构造演化表明,花岗闪长岩岩浆源区为下地壳变玄武岩石,形成于同碰撞构造背景。
英文摘要:
      This paper reports a detailed study of petrology, U-Pb zircon dating and geochemical characteristic for Maozangsi granodiorite in North Qilian Mountains. The Maozangsi pluton is mainly consisted of granodiorite, and the SHRIMP U-Pb zircon dating yield a magma crystallization age of (456±3)Ma for this pluton. The Maozangsi granodiorite has high SiO2 (65.1%~73.0%) and low Mg# (18~32) values, its K2O/Na2O ratio is 0.82~1.37 while its A/NKC ratio is 0.9~1.1, belonging to high K calc-alkaline granite. It is rich in LILE and depleted in HFSE. The REE data shows strongly frantionated REE patterns, with (La/Yb)N ratio of 11.1~34.1 and δEu value of 0.6~0.8. The geochemical characteristics and evolutionary history of granitoids in North Qilian orogen belt indicate that the magma of the granodiorite was derived from partial melting of basaltic rock in lower crust and formed in collisional tectonic setting.
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