| 藏北阿翁错复式岩体及其暗色微粒包体年龄、地球化学与地球动力学意义 |
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| 引用本文： | 雷传扬,吴建亮,尹显科,刘文,王波,李威,袁华云,张伟,尹滔,裴亚伦.藏北阿翁错复式岩体及其暗色微粒包体年龄、地球化学与地球动力学意义[J].地质通报,2019,38(4):494-508. |
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| 作者姓名： | 雷传扬 吴建亮 尹显科 刘文 王波 李威 袁华云 张伟 尹滔 裴亚伦 |
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| 作者单位： | 成都理工大学, 四川 成都 610059;四川省地质调查院, 四川 成都 610081,四川省地质调查院, 四川 成都 610081,四川省地质调查院, 四川 成都 610081,四川省地质调查院, 四川 成都 610081,四川省地质调查院, 四川 成都 610081,四川省地质调查院, 四川 成都 610081,四川省地质调查院, 四川 成都 610081,四川省地质调查院, 四川 成都 610081,四川省地质调查院, 四川 成都 610081,四川省地质调查院, 四川 成都 610081 |
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| 基金项目： | 中国地质调查局项目《班公湖-怒江成矿带铜多金属矿产资源基地调查》（编号：DD20160026） |
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| 摘 要： | 对班公湖-怒江缝合带西段阿翁错复式岩体及其暗色微粒包体开展了岩石学、全岩地球化学及同位素年龄研究。结果表明,阿翁错复式岩体中出露大量闪长质暗色微粒包体,包体具典型的火成结构,发育针状磷灰石。寄主岩与包体均为准铝质、高钾钙碱性-钾玄岩系列过渡岩石,主要氧化物含量在Harker图解上具有良好的线性关系,稀土元素配分曲线和微量元素原始地幔标准化蛛网图具有高度的一致性,表明二者具有强烈的地球化学亲源关系,且经历了相似的岩浆演化过程;主量、微量元素同分母协变图中包体和寄主岩表现为良好的线性关系,表明二者之间的演化与岩浆混合作用关系密切;包体的原始岩浆可能来源于受俯冲带流体交代的地幔楔,寄主岩为幔源岩浆与熔融下地壳岩浆混合的产物,以熔融下地壳岩浆为主。寄主岩和暗色微粒包体的成岩年龄分别为109.1±1.0Ma和107.4±0.7Ma,显示岩浆混合作用发生在早白垩世。结合班公湖-怒江缝合带的演化及构造判别,认为阿翁错复式岩体形成于班公湖-怒江特提斯洋软碰撞阶段,为受俯冲带流体交代的地幔楔上升与其诱发的下地壳花岗质岩浆混合作用的产物。
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| 关 键 词： | 阿翁错复式岩体 暗色微粒包体 地球化学 岩浆混合作用 岩石成因 藏北 |
| 收稿时间： | 2017/5/25 0:00:00 |
| 修稿时间： | 2017/9/16 0:00:00 |
Geochronology, geochemistry and geodynamic significance of Awengcuo composite pluton and its dark microgranular enclaves in the north of Tibet |
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| LEI Chuanyang,WU Jianliang,YIN Xianke,LIU Wen,WANG Bo,LI Wei,YUAN Huayun,ZHANG Wei,YIN Tao and PEI Yalun.Geochronology, geochemistry and geodynamic significance of Awengcuo composite pluton and its dark microgranular enclaves in the north of Tibet[J].Geologcal Bulletin OF China,2019,38(4):494-508. |
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| Authors: | LEI Chuanyang WU Jianliang YIN Xianke LIU Wen WANG Bo LI Wei YUAN Huayun ZHANG Wei YIN Tao and PEI Yalun |
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| Institution: | College of Earth Sciences, Chengdu University of Technology, Chengdu 610059, Sichuan, China;Geological Survey of Sichuan Province, Chengdu 610081, Sichuan, China,Geological Survey of Sichuan Province, Chengdu 610081, Sichuan, China,Geological Survey of Sichuan Province, Chengdu 610081, Sichuan, China,Geological Survey of Sichuan Province, Chengdu 610081, Sichuan, China,Geological Survey of Sichuan Province, Chengdu 610081, Sichuan, China,Geological Survey of Sichuan Province, Chengdu 610081, Sichuan, China,Geological Survey of Sichuan Province, Chengdu 610081, Sichuan, China,Geological Survey of Sichuan Province, Chengdu 610081, Sichuan, China,Geological Survey of Sichuan Province, Chengdu 610081, Sichuan, China and Geological Survey of Sichuan Province, Chengdu 610081, Sichuan, China |
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| Abstract: | The petrology, whole rock geochemistry and U-Pb isotopic chronology of the Awengcuo composite pluton and its dark microgranular enclaves in the western part of Bangong Co-Nujiang suture zone were studied in this paper. The results show that Awengcuo composite pluton contains abundant mafic magmatic enclaves (MMEs) comprising mainly biotitic diorite. The MMEs display igneous texture and long prisms of apatite. Host rock and MMEs are transitional rock belonging to quasi-aluminum, highcalcium alkaline-potassium kaolin series, and the main oxides in the Harker diagram show good linear relationship. Rare earth element distribution curve and normalized spider web for trace element primitive mantle exhibit a high degree of consistency. It shows that there is a strong geophysical relationship between the two groups, which experienced similar magmatic evolution processes. A good linear relationship is shown between the host rock and the inclusions in the denominator covariant map for the major and trace elements. The original magma of the inclusions might have been derived from the mantle wedge by fluid of the subduction zone, whereas the host rock is a product of mantle-derived magma mixed with the molten lower crust magma, mainly molten lower crust magma. The LA-ICP-MS single-zircon U-Pb dating demonstrates that the magmatic age is 109.1±1.0Ma for the host rock and 107.4±0.7Ma for the enclave. The two ages are basically the same, suggesting that the mixing event took place during the period of Early Cretaceous. Combined with the evolution and tectonic discrimination of Bangong Co-Nujiang suture zone, it is concluded that the Awengcuo composite pluton was formed at the soft-collision stage in the Bangong Co-Nujiang Tethyan Ocean, being a product of mantle wedge ascending with the derived mixture of subduction zone fluid and magma. |
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| Keywords: | Awengcuo composite plutons dark microgranular enclaves geochemistry magmatic mixing petrogenesis north of Tibet |
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