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现代地质 ›› 2022, Vol. 36 ›› Issue (03): 862-875.DOI: 10.19657/j.geoscience.1000-8527.2021.151

• 岩石学 • 上一篇    下一篇

粤西北大桂山岩体LA-ICP-MS锆石U-Pb测年、岩石成因及构造环境分析

张宏辉1(), 谢财富2(), 陈凯3, 袁永盛1, 余杨忠1, 张沥元4, 陈贵仁1, 李鸿1, 詹华思5, 石海涛6, 蔡泉宇1, 于一帆1   

  1. 1.中国地质调查局 昆明自然资源综合调查中心,云南 昆明 650100
    2.东华理工大学,江西 南昌 330000
    3.海南武华金源矿业股份有限公司,海南 东方 572633
    4.中国地质调查局 地球物理调查中心,河北 廊坊 065000
    5.中国地质调查局 海口海洋地质调查中心,海南 海口 571127
    6.中国地质调查局 乌鲁木齐自然资源综合调查中心,新疆 乌鲁木齐 830000
  • 收稿日期:2021-07-07 修回日期:2021-08-11 出版日期:2022-06-10 发布日期:2022-07-19
  • 通讯作者: 谢财富
  • 作者简介:谢财富,男,博士,教授,1965年出生,岩石地球化学专业,主要从事岩浆岩与矿床学研究。Email: cfxie@ecut.edu.cn
    张宏辉,男,工程师,1989年出生,资源勘查工程(固体矿产)专业,主要从事区域地质调查工作。Email: 673872084@qq.com
  • 基金资助:
    中国地质调查局项目“重要矿产资源调查评价”子项目“广东南岭成矿带洽水圩、横石圩幅1:5万区域地质矿产调查”(12120114083071)

LA-ICP-MS Zircon U-Pb Dating,Petrogenesis and Tectonic Setting of the Daguishan Pluton in Northwestern Guangdong

ZHANG Honghui1(), XIE Caifu2(), CHEN Kai3, YUAN Yongsheng1, YU Yangzhong1, ZHANG Liyuan4, CHEN Guiren1, LI Hong1, ZHAN Huasi5, SHI Haitao6, CAI Quanyu1, YU Yifan1   

  1. 1. Kunming Natura Resource Comprehensive Investigation Center of China Geological Survey,Kunming,Yunnan 650100, China
    2. East China University of Technology, Nanchang,Jiangxi 330000,China
    3. Hainan Wuhuajinyuan Mining Co., Ltd., Dongfang,Hainan 572633,China
    4. Geophysical Investigation Center of China Geological Survey, Langfang,Hebei 065000,China
    5. Haikou Marine Geological Investigation Center of China Geological Survey,Haikou,Hainan 571127,China
    6. Urumqi Natural Resources Comprehensive Investigation Center of China Geological Survey, Urumqi,Xinjiang 830000, China
  • Received:2021-07-07 Revised:2021-08-11 Online:2022-06-10 Published:2022-07-19
  • Contact: XIE Caifu

摘要:

为了加深对粤西北地区加里东期岩浆岩演化的认识,对粤西北地区大桂山岩体进行了岩石学、岩相学、同位素年代学、岩石地球化学及Sm-Nd同位素地球化学等研究。研究显示:大桂山岩体位于广东佛冈复式岩体的北西缘,岩性为中粗粒含斑黑云母正长花岗岩;利用LA-ICP-MS锆石U-Pb法测得其年龄为(445.9±3.6) Ma,属晚奥陶世侵入岩;岩石地球化学具有高硅、富钾、高分异指数和低钙、低镁、贫铁的特征;稀土元素总量中等-偏低,轻重稀土元素分馏程度较低,具明显的负Eu异常;微量元素表现为大离子亲石元素Rb、Th、U、K、La、Ce、Nd等的富集,亏损P、Sr、Ba、Ti等高场强元素;(87Sr/86Sr)i为0.025 3~0.100 2,εNd(t)值较高,为-3.15~-5.26,TDM2值较低。以上特征表明大桂山岩体为高分异或低熔融程度的铝质A型花岗岩,其源区为成熟度较低的地壳物质或者是一定比例壳幔物质的混合,因造山带垮塌、软流圈上涌引起地壳伸展,由于地幔上隆,幔源基性岩浆岩和钾玄质岩浆岩上侵或底侵而形成。

关键词: 佛冈岩体, U-Pb测年, Nd同位素, 花岗岩, 晚奥陶世

Abstract:

To deepen our understanding on Caledonian magmatic rock evolution in northwest Guangdong, the petrology, petrography, isotope chronology, petrogeochemistry and Sm-Nd isotope geochemistry of the Daguishan pluton in northwest Guangdong is carried out.The result shows the Daguishan pluton is located in the northwest margin of the Fogang complex pluton in Guangdong Province, and the lithology is medium-/coarse-grained biotite syenogranite.LA-ICP-MS zircon U-Pb dating shows that its age to be (445.9±3.6) Ma, belonging to the Late Ordovician intrusive rock.The Daguishan pluton is rich in Si,K, high differentiation index and low Ca, Mg and Fe. The rocks show the total amount of REE is medium to low, the fractionation degree of LREE and HREE is low with negative Eu anomaly. The monzogranite is also enriched in LILEs(e.g., Rb,Th,U,K,La,Ce and Nd) and depleted in P,Sr,Ba and Ti. (87Sr/86Sr)i value is 0.025,3-0.100,2, and εNd(t) value is -3.15--5.26 with lower TDM2 value. Based on the geochronological and geochemical characteristics of the Daguishan pluton, it is inferred that the source area is the crust material with low maturity or the mixing of a certain proportion of crust mantle material. The crust gets extended due to the collapse of orogenic belt and the upwelling of asthenosphere. Due to mantle uplift, mantle-derived mafic magmatites and potassic-basalt magmatites were formed by upwelling or underplating.

Key words: Fogang pluton, U-Pb dating, Nd isotope, granite, Late Ordovician

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