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现代地质 ›› 2022, Vol. 36 ›› Issue (01): 333-346.DOI: 10.19657/j.geoscience.1000-8527.2022.01.30

• 地球化学 • 上一篇    下一篇

胶东艾山岩体二长花岗岩地球化学、锆石U-Pb年代学及Lu-Hf同位素特征研究

李秀章1(), 王立功1(), 李衣鑫2, 王英鹏1, 于晓卫1, 张文1, 郭瑞朋1, 刘汉栋1   

  1. 1. 山东省地质调查院,山东 济南 250013
    2. 桂林理工大学 地球科学学院,广西 桂林 541006
  • 收稿日期:2021-03-31 修回日期:2021-09-03 出版日期:2022-02-10 发布日期:2022-03-08
  • 通讯作者: 王立功
  • 作者简介:王立功,男,高级工程师,1986年出生,矿物学、岩石学、矿床学专业,主要从事地质勘查及矿床学研究。Email: 346020775@qq.com
    李秀章,男,研究员,1969年出生,矿物学、岩石学、矿床学专业,主要从事地质勘查及矿床学研究。Email: lixiuzhang4117@126.com
  • 基金资助:
    国家重点研发计划项目“深部资源预测系统技术研究与示范”(2017YFC0601506);山东省自然科学基金面上项目(ZR2020MD033);山东省地质勘查项目(鲁勘字(2019)1号,鲁勘字(2012)4号,鲁勘字(2014)7号,鲁勘字(2018)19号)

Geochemistry, Zircon U-Pb Chronology and Lu-Hf Isotope Characteristics of Monzogranites from Aishan Pluton in Jiaodong Peninsula

LI Xiuzhang1(), WANG Ligong1(), LI Yixin2, WANG Yingpeng1, YU Xiaowei1, ZHANG Wen1, GUO Ruipeng1, LIU Handong1   

  1. 1. Shandong Institute of Geological Survey, Jinan, Shandong 250013, China
    2. College of Earth Sciences, Guilin University of Technology, Guilin, Guangxi 541006, China
  • Received:2021-03-31 Revised:2021-09-03 Online:2022-02-10 Published:2022-03-08
  • Contact: WANG Ligong

摘要:

胶东地区大规模金成矿作用发生于125~110 Ma,与金成矿作用同期的早白垩世晚期艾山岩体出露于华北克拉通东缘,由深成相的石英闪长岩-似斑状二长花岗岩类及浅成相的闪长玢岩、花岗斑岩等组成,岩体发育岩浆暗色包体。对艾山二长花岗岩开展了岩相学、岩石地球化学、锆石LA-ICP-MS年代学和Lu-Hf同位素测试和研究,探讨了该岩体的岩石类型、形成时代、岩浆源区与岩石成因。艾山岩体锆石U-Pb 年龄为(115±1) Ma,Na2O>3.47,A/CNK<1.35,高Y 含量(8.2×10-6~210.5×10-6),低Sr/Y比值(19.5~67.3),具有明显的稀土元素分馏(LREE/HREE=28.43~34.72,(La/Yb)N=46.38~56.74),负铕异常(δEu=0.75~0.83),为一套准铝质-弱过铝质的高钾钙碱性岩系,显示出I型花岗岩的特征。艾山二长花岗岩的岩浆锆石εHf(t)值为-19.7~-16.0,对应的Hf二阶段模式年龄TDM2为2.18~2.42 Ga。根据岩石学、地球化学和Lu-Hf同位素特征,并结合前人的研究成果,认为艾山二长花岗岩是壳源酸性岩浆与幔源中基性岩浆混合而成,壳源岩浆源区主要为古元古代、新太古代陆壳物质。

关键词: 艾山岩体, 二长花岗岩, 锆石U-Pb年龄, Lu-Hf同位素, 胶东

Abstract:

The large-scale gold mineralization in Jiaodong Peninsula occurred from 125 to 110 Ma. Early Cretaceous Aishan pluton, coincided with the gold mineralization, is distributed in the eastern margin of North China Craton. Aishan pluton is composed of deep-facies quartz diorite-porphyry monzonitic granite and shallow-facies diorite porphyry, granite porphyry, etc., and develops mafic enclaves. Based on the studies of the petrography, geochemistry, zircon LA-ICP-MS U-Pb dating and Lu-Hf isotopic constitution of Aishan monzogranites, this paper discusses the petrologic classification, forming age, magmatic source and petrogenesis. Zircon U-Pb age of Aishan pluton is( 115±1)Ma. Aishan pluton is characterized by Na2O>3.47, A/CNK<1.35, high Y content (8.2×10-6-210.5×10-6), low Sr/Y ratio (19.5-67.3), with obvious rare earth element fractionation (LREE/HREE=28.43-34.72, (La/Yb)N=46.38-56.74), and negative Eu anomaly (δEu=0.75-0.83). Aishan pluton is a set of quasi-aluminous-weak peraluminous high-potassium calc-alkaline rock series, showing the characteristics of I-type granite. Aishan monzogranites have zircon εHf(t) values of -19.7 to -16.0, and two-stage Hf model ages (TDM2) vary in range of 2.18-2.42 Ga. According to the petrology, geochemistry and Lu-Hf isotopic constitution, combined with the results of previous studies on the genesis of Weideshan granite, the authors hold that Aishan monzogranites are a production of mixture between crustal acid magma and mantle intermediate-basic magma. The magma mainly derived from ancient Proterozoic and Neoarchean continental crust material.

Key words: Aishan pluton, monzogranite, zircon U-Pb age, Lu-Hf isotope, Jiaodong Peninsula

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