太行山麻棚地区高Ba-Sr花岗质侵入岩的地球化学、锆石U-Pb年龄和Hf同位素特征及其地质意义  

Geochemistry,zircon U-Pb age and Hf isotope characteristics of high-Ba-Sr granites in Mapeng area,Taihang Mountains and their geological significance

作　　者：程海峰 杜利林[2] 杨崇辉[2] 苏荣昆 孟庆涛 刘广 王明明 张正平 井晶晶 王晓东 CHENG Hai-feng;DU Li-lin;YANG Chong-hui;SU Rong-kun;MENG Qing-tao;LIU Guang;WANG Ming-ming;ZHANG Zheng-ping;JING Jing-jing;WANG Xiao-dong(Institute of Regional Geological Survey of Hebei Province,Langfang 065000,China;Institute of Geology,Chinese Academy of Geological Sciences,Bejing 100037,China;Petroleum Exploration&Production Research Institute of Northwest Oilfield Company,SINOPEC,Urumqi 830011,China;The Forth Geological Brigade of Hebei Bureau of Geology and Mineral Resources Exploration,Chengde 067000,China)

机构地区：[1]河北省区域地质调查院,河北廊坊065000 [2]中国地质科学院地质研究所,北京100037 [3]中国石化西北油田分公司勘探开发研究院,新疆乌鲁木齐830011 [4]河北省地质矿产勘查开发局第四地质大队,河北承德067000

出　　处：《岩石矿物学杂志》2024年第3期719-736,共18页Acta Petrologica et Mineralogica

基　　金：河北省1∶5万区域地质调查项目(13000022P00F2D410209L,13000023P00F2D4102673,13000024P00F2D410574E);中国地质调查局地质调查项目(DD20190003);河北省自然科学基金资助项目(D2021403028)。

摘　　要：华北克拉通经历了长期而复杂的地质过程,中生代时期在太行山地区构造岩浆活动强烈,形成了一系列中酸性岩体。麻棚岩体位于太行山北段,侵位于新太古代片麻岩和表壳岩中,由中心向边缘分别出露似斑状二长花岗岩、花岗闪长岩和石英闪长岩。前人已经对麻棚岩体进行过岩石学、岩石化学、岩体成因类型和年代学等多方面的研究,其花岗岩类型仍存有争议。本文对麻棚岩体进行了系统的岩石地球化学、锆石SHRIMP U-Pb同位素年代学分析和Lu-Hf同位素组成研究,进一步探讨了麻棚岩体的地球化学类型、形成时代和岩浆源区性质。岩石地球化学特征表明麻棚岩体具有较高的SiO_(2)、Na_(2)O+K_(2)O、Ba、Sr、LREE含量和K_(2)O/Na_(2)O值,较低的Al_(2)O_(3)、MgO、Rb、Nb、Ta、Th、U、Y、HREE含量和Mg^(#)值,无明显的Eu异常,明显亏损Nb、Ta、P、Ti等高场强元素,属于高Ba-Sr花岗岩。新获得的3个不同相带岩石的锆石SHRIMP U-Pb同位素206Pb/238U加权平均年龄为129.4±1.4、131.2±2.2和129.5±1.3 Ma,且具有相似主量元素组成及稀土和微量元素分布模式,反映了麻棚岩体为同一期岩浆活动产物。Lu-Hf同位素测试分析数据计算获得麻棚岩体岩浆锆石的εHf(t)值为-27.00~-15.44,二阶段模式年龄t_(DM2)为2 358~1 765 Ma。麻棚岩体是前寒武纪变质基底部分熔融形成的岩浆与幔源岩浆混合作用的结果。The North China Craton(NCC)has undergone a long and complicated geological process.During the Mesozoic,a series of intermediate-acid granitoids were formed in the Taihang Mountains.Mapeng granitic pluton is located in the northern part of Taihang Mountains,emplaced in Fuping complex,with porphyritic monzonitic granite,granodiorite and quartz diorite exposed from the center to the edge.The petrology,petrochemistry,genetic type of Mapeng granitic pluton have been studied by predecessors,but the type and source of granitic pluton are still con-troversial.In this paper,the petrochemistry,zircon SHRIMP U-Pb isotopic chronology and Lu-Hf isotopic composi-tion of porphyritic monzonitic granite,granodiorite and quartz diorite in Mapeng pluton are systematically studied,and the geochemical type,formation age and magma source nature of Mapeng granite are further discussed.Geo-chemical magmas show that the Mapeng granite has high SiO_(2)、Na_(2)O+K_(2)O、Ba、Sr、LREE and the ratio of K_(2)O/Na_(2)O,lower Al_(2)O_(3)、Mg O、Rb、Nb、Ta、Th、U、Y、HREE and Mg#value,no obvious Eu anomaly and obvious depletion of high field strength elements such as Nb,Ta,P and Ti.The SHRIMP U-Pb isotopic ages of the three newly obtained granites with different facies belts are 129.4±1.4 Ma,131.2±2.2 Ma,129.5±1.3 Ma,and they have similar major element compositions and REE and trace element distribution patterns.It also reflects that the Mapeng pluton is a magmatic activity of the same period,and has undergone rapid emplacement and cooling crystal-lization.Lu-Hf isotopic analysis shows that theεHf(t)value of magmatic zircon from the Mapeng granite is-27.00--15.44,and the two-stage model age tDM2 is 2358-1765 Ma.The magma source of the Mapeng granite is the result of mixing of mantle magma and magma formed by partial melting of Precambrian metamorphic basement.

关 键 词：麻棚岩体 锆石SHRIMP U-Pb年龄 LU-HF同位素 高Ba-Sr花岗岩 

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