| 柴北缘察汗诺辉长岩成因:岩石地球化学、锆石U-Pb年代学与Lu-Hf同位素制约 |
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| 引用本文： | 程婷婷,牛漫兰,吴齐,夏文静,李秀财.柴北缘察汗诺辉长岩成因:岩石地球化学、锆石U-Pb年代学与Lu-Hf同位素制约[J].地质科学,2015,0(3):741-755. |
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| 作者姓名： | 程婷婷 牛漫兰 吴齐 夏文静 李秀财 |
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| 作者单位： | 1. 合肥工业大学资源与环境工程学院 合肥 230009;
2. 中国科学院大学地球科学学院 北京 100049 |
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| 摘 要： | 柴北缘察汗诺地区广泛发育中生代辉长岩、闪长岩、花岗闪长岩和花岗岩。LA-ICP-MS锆石U-Pb测年结果表明, 辉长岩206 Pb/238 U加权平均年龄为246±0.7 Ma, 形成于中三叠世早期。辉长岩SiO2(50.61%~54.41%)和全碱含量(2.36%~3.72%)低, 里特曼指数为0.54~1.12, 属于中钾钙碱性系列岩石; Mg#(73~79)和Cr(342×10-6~753×10-6)、Ni(45.1×10-6~145×10-6)含量高, LREE/HREE为4.74~5.67, 富集U、Th等大离子亲石元素, 亏损Nb、Ta、Ti等高场强元素, 呈现出与典型俯冲作用密切相关的弧岩浆岩特征。锆石Lu-Hf同位素分析结果显示, 辉长岩εHf(t)值为-2.24~+1.37, 研究表明察汗诺辉长岩岩浆源区因受俯冲板片流体交代而富集, 岩石主要起源于富集地幔的部分熔融。空间上, 察汗诺辉长岩与东昆仑布尔汗布达、鄂拉山以及西秦岭同仁-泽库等同时代的钙碱性岩浆岩, 共同构成了古特提斯洋向北俯冲的大陆边缘弧。
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| 关 键 词： | 察汗诺辉长岩 岩浆弧 古特提斯 柴北缘 |
| 收稿时间： | 2014-11-16 |
| 修稿时间： | 2014-11-16; |
Petrogenesis of the Chahannuo gabbro on the northern margin of Qaidam Basin: Constraint from geochemistry,zircon U-Pb dating and Lu-Hf isotopes |
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| Cheng Tingting,Niu Manlan,Wu Qi,Xia Wenjing,Li Xiucai.Petrogenesis of the Chahannuo gabbro on the northern margin of Qaidam Basin: Constraint from geochemistry,zircon U-Pb dating and Lu-Hf isotopes[J].Chinese Journal of Geology,2015,0(3):741-755. |
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| Authors: | Cheng Tingting Niu Manlan Wu Qi Xia Wenjing Li Xiucai |
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| Institution: | 1. Department of Resources and Environment, Hefei University of Technology, Hefei 230009;
2. College of Earth Science, University of Chinese Academy of Sciences, Beijing 100049 |
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| Abstract: | The Mesozoic gabbro, diorite, granodiorite and granite are widespread at Chahannuo area in the north margin of Qaidam terrane. LA-ICP-MS zircon dating yields Middle Triassic age of 246±0.7 Ma for the Chahannuo gabbro. The gabbros have low SiO2(50.6%~54.41%), total alkali contents(2.36%~3.72%), and low σ value caring from 0.54 to 1.12, indicating that they are belong to medium-K calc-alkaline series. They are characterized by elevated high MgO, Mg#, Cr, Ni, enriched LREE, LILEs(U, Th, K), and depleted in HREE, HFSEs(Nb, Ta, Ti). The gabbro zircons εHf(t)changed from -2.24 to +1.37. These indicated that gabbros were dominatly derived by the partial melting of enriched lithosphere which had been metasomatism the fluid from the subducted slab. The Chahannuo gabbro were contemporary with the calc-alkaline magmatism from Buerhanbuda in the East Kunlun orogen, Elashan and Tongren-Zeku area in the West Qinling orogeny. These calc-alkaline magmatism constituted a active continental margin arc formed by the northern subduction of Paleo-Tethys Ocean. |
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| Keywords: | Chahannuo gabbro Magma arc Paleo-Tethys Northern margin of Qaidam Basin |
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