| 浙江中部芙蓉山花岗斑岩及包体岩石地球化学研究 |
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| 引用本文： | 杜秀玲,汪方跃,闫海洋,顾海欧,孙贺,葛粲.浙江中部芙蓉山花岗斑岩及包体岩石地球化学研究[J].地质论评,2022,68(1):18-46. |
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| 作者姓名： | 杜秀玲 汪方跃 闫海洋 顾海欧 孙贺 葛粲 |
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| 作者单位： | 合肥工业大学资源与环境工程学院,合肥,230009;合肥工业大学矿床成因与勘查技术研究中心,合肥,230009;中国科学院壳幔物质与环境重点实验室,中国科学技术大学地球和空间科学学院,合肥,230026 |
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| 基金项目： | 国家重点研发计划“深地资源勘查开采”重点专项(2016YFC0600404)、 国家自然科学基金项目(41873034) |
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| 摘 要： | 花岗岩的源区、温压条件及与其他岩石的共生组合的研究可以限定其形成构造背景,了解其形成的深部动力学过程.本文对浙江中部中生代芙蓉山花岗斑岩及其暗色包体开展了全岩主微量元素、锆石U-Pb年代学和Hf同位素、Ti温度计和全岩Sr—Nd同位素研究,探讨芙蓉山花岗斑岩的成因类型、源区特征及其与镁铁质包体之间的关系,并进一步限定其...
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| 关 键 词： | 赣杭构造带 芙蓉山岩体 I型花岗岩 岩浆混合 古太平洋俯冲 洋壳俯冲后撤 |
| 收稿时间： | 2021/4/16 0:00:00 |
| 修稿时间： | 2021/8/27 0:00:00 |
Geochemistry of Furongshan Granitic Porphyry and Mafic Microgranular Enclaves in Central Zhejiang Province |
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| DU Xiuling,WANG Fangyue,YAN Haiyang,GU Haiou,SUN He,GE Can.Geochemistry of Furongshan Granitic Porphyry and Mafic Microgranular Enclaves in Central Zhejiang Province[J].Geological Review,2022,68(1):18-46. |
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| Authors: | DU Xiuling WANG Fangyue YAN Haiyang GU Haiou SUN He GE Can |
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| Institution: | (School of Resources and Environmental Engineering,Hefei University of Technology,Hefei,230009;Ore Deposit and Exploration Center(ODEC),Hefei University of Technology,Hefei,230009;Chinese Academy of Sciences(CAS)Key Laboratory of Crust—Mantle Materials and Environments,School of Earth and Space Sciences,University of Science and Technology of China,Hefei,230026) |
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| Abstract: | Objectives:By comparing the geochemistry and isotopic compositions of Furongshan granitic porphyry and mafic microgranular enclaves from central Zhejiang province,the genesis of Furongshan granitic porphyry,the characteristic of source area and the relationship between granitic porphyry and mafic microgranular enclaves are able to be explored,through which further constraints of the tectonic setting,and the geodynamic process of the Late Mesozoic crust—mantle magma interaction in the South China Plate could be revealed.Methods:Based on the field work,through the microscope observation,the whole rock chemical analysis,LA ICP-MS zircon U-Pb dating,Ti-thermometer,Sr—Nd isotopic compositions and Hf isotopes of Mesozoic host granitic porphyry and their mafic microgranular enclaves(MMEs)from Furongshan pluton.Results:Zircon U-Pb dating results show that the weighted mean n(206Pb)/n(238U)age of Furongshan granitic porphyry is 133.6±1.6 Ma(MSWD=2.1,2σ),and the weighted mean n(206Pb)/n(238U)age of mafic microgranular enclaves is 130.3±4.2 Ma(MSWD=5.8,2σ).Their diagenetic ages are basically the same and formed in the early Cretaceous.The Furongshan granitic porphyry are sub-alkaline with low Ga/Al(<2.6)(10000·Ga/Al=2.19~2.48)and high Na2O(2.75%~4.5%),enriched in alkalis(Na2O+K2O=7.93%~8.75%).And calculated results based on zircon Ti-thermometry indicate a relatively low magmatic temperature(631~690℃).The Furongshan granitic porphyry has a large range of zircon εHf(t)values(-10.9~-1.1)and exhibits initialn(87Sr)/n(86Sr)]i ratios of 0.7062 to 0.7078 andεNd(t)values of-5.6 to-4.7,the enclaves have relatively uniform initialn(87Sr)/n(86Sr)]i ratios of 0.7071 to 0.7079 andεNd(t)values of-3.8 to-2.8.Conclusions:These petrographical and geochemical characteristics of the Furongshan granitic porphyry suggest I-type granitic affinities rather than A-type granitic affinities.Field and petrography and geochemistry characteristics suggesting Furongshan mafic microgranular enclaves and host granitic porphyry were formed by magma mixing.The source of mafic microgranular enclaves may be derived from the subduction metasomatic mantle,and the Furongshan granitic porphyry was formed by the fractional crystallization after the mixing of ancient K-rich crustal melt and metasomatic mantle melt.The modeling results indicate that the hybrid magma may have been formed by~80%basaltic and~20%felsic melts.The Furongshan K-rich I type granitic porphyry and the enclaves in the central Zhejiang province may indicate that they were formed in the tectonic setting of weak extension at the earlier stage of the roll-back of paleo-Pacific plate subduction. |
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| Keywords: | Furongshan I-type granites Magma mixing Paleo-Pacific plate subduction Oceanic crust subduction and retreat |
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