| Late Paleozoic to Mesozoic Intrusions Distribution in the North Sanjiang Orogenic Belt, Southwest China: Evidence from Zircon U–Pb Dating and Geochemistry |
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| 作者姓名： | GONG Xuejing YANG Zhusen MENG Xiangjin PAN Xiaofei WANG Qian ZHANG Lejun |
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| 基金项目： | This work was funded by the National Key Research and Development Program of China ‘Deep Structure and Ore–forming Process of Main Mineralization system in Tibetan Orogen’ (NO.2016YFC0600300), the National Basic Research Program of China (NO.2011CB403104), the China Geological Survey (NO.12120113037901), the National Nature Science Foundation of China(NO.41320104004). Two anonymous reviewers are thanked for thoughtful and helpful reviews. We thank Prof. Zengqian Hou, Prof. Zhiming Yang, Prof. Qingfei Wang and Dr. Chao Duan for the detailed and insightful suggestions. |
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| 摘 要： | A mosaic of terranes or blocks and associated Late Paleozoic to Mesozoic sutures are characteristics of the north Sanjiang orogenic belt (NSOB). A detailed field study and sampling across the three magmatic belts in north Sanjiang orogenic belt, which are the Jomda–Weixi magmatic belt, the Yidun magmatic belt and the Northeast Lhasa magmatic belt, yield abundant data that demonstrate multiphase magmatism took place during the late Paleozoic to early Mesozoic. 9 new zircon LA–ICP–MS U–Pb ages and 160 published geochronological data have identified five continuous episodes of magma activities in the NSOB from the Late Paleozoic to Mesozoic: the Late Permian to Early Triassic (c. 261–230 Ma); the Middle to Late Triassic (c. 229–210 Ma); the Early to Middle Jurassic (c. 206–165 Ma); the Early Cretaceous (c. 138–110 Ma) and the Late Cretaceous (c. 103–75 Ma). 105 new and 830 published geochemical data reveal that the intrusive rocks in different episodes have distinct geochemical compositions. The Late Permian to Early Triassic intrusive rocks are all distributed in the Jomda–Weixi magmatic belt, showing arc–like characteristics; the Middle to Late Triassic intrusive rocks widely distributed in both Jomda–Weixi and Yidun magmatic belts, also demonstrating volcanic–arc granite features; the Early to Middle Jurassic intrusive rocks are mostly exposed in the easternmost Yidun magmatic belt and scattered in the westernmost Yangtza Block along the Garzê–Litang suture, showing the properties of syn–collisional granite; nearly all the Early Cretaceous intrusive rocks distributed in the NE Lhasa magmatic belt along Bangong suture, exhibiting both arc–like and syn–collision–like characteristics; and the Late Cretaceous intrusive rocks mainly exposed in the westernmost Yidun magmatic belt, with A–type granite features. These suggest that the co–collision related magmatism in Indosinian period developed in the central and eastern parts of NSOB while the Yanshan period co–collision related magmatism mainly occurred in the west area. In detail, the earliest magmatism developed in late Permian to Triassic and formed the Jomda–Wei magmatic belt, then magmatic activity migrated eastwards and westwards, forming the Yidun magmatic bellt, the magmatism weakend at the end of late Triassic, until the explosure of the magmatic activity occurred in early Cretaceous in the west NSOB, forming the NE Lhasa magmatic belt. Then the magmatism migrated eastwards and made an impact on the within–plate magmatism in Yidun magmatic belt in late Cretaceous.
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| 关 键 词： | intrusions distribution granitoid age and geochemistry Paleozoic and Mesozoic subduction–related magmatic belt Sanjiang orogenic belt |
| 收稿时间： | 2017/1/19 0:00:00 |
| 修稿时间： | 2017/3/20 0:00:00 |
Late Paleozoic to Mesozoic Intrusions Distribution in the North Sanjiang Orogenic Belt,Southwest China: Evidence from Zircon U–Pb Dating and Geochemistry |
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| Authors: | GONG Xuejing YANG Zhusen MENG Xiangjin PAN Xiaofei WANG Qian and ZHANG Lejun |
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| Institution: | 1 School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China
2 MLR Key Laboratory and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of
Geological Sciences, Beijing 100037, China,2 MLR Key Laboratory and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of
Geological Sciences, Beijing 100037, China,2 MLR Key Laboratory and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of
Geological Sciences, Beijing 100037, China,3 Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China,2 MLR Key Laboratory and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of
Geological Sciences, Beijing 100037, China and 4 ARC Centre of Excellence in Ore Deposits (CODES), University of Tasmania, Private Bag 79, Hobart,
TAS 7001, Australia
5 Transforming the Mining Value Chain, an ARC Industrial Transformation Research Hub, University of
Tasmania, Private Bag 79, Hobart, TAS 7001, Australia |
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| Abstract: | A mosaic of terranes or blocks and associated Late Paleozoic to Mesozoic sutures are characteristics of the north Sanjiang orogenic belt (NSOB). A detailed field study and sampling across the three magmatic belts in north Sanjiang orogenic belt, which are the Jomda–Weixi magmatic belt, the Yidun magmatic belt and the Northeast Lhasa magmatic belt, yield abundant data that demonstrate multiphase magmatism took place during the late Paleozoic to early Mesozoic. 9 new zircon LA–ICP–MS U–Pb ages and 160 published geochronological data have identified five continuous episodes of magma activities in the NSOB from the Late Paleozoic to Mesozoic: the Late Permian to Early Triassic (c. 261–230 Ma); the Middle to Late Triassic (c. 229–210 Ma); the Early to Middle Jurassic (c. 206–165 Ma); the Early Cretaceous (c. 138–110 Ma) and the Late Cretaceous (c. 103–75 Ma). 105 new and 830 published geochemical data reveal that the intrusive rocks in different episodes have distinct geochemical compositions. The Late Permian to Early Triassic intrusive rocks are all distributed in the Jomda–Weixi magmatic belt, showing arc–like characteristics; the Middle to Late Triassic intrusive rocks widely distributed in both Jomda–Weixi and Yidun magmatic belts, also demonstrating volcanic–arc granite features; the Early to Middle Jurassic intrusive rocks are mostly exposed in the easternmost Yidun magmatic belt and scattered in the westernmost Yangtza Block along the Garzê–Litang suture, showing the properties of syn–collisional granite; nearly all the Early Cretaceous intrusive rocks distributed in the NE Lhasa magmatic belt along Bangong suture, exhibiting both arc–like and syn–collision–like characteristics; and the Late Cretaceous intrusive rocks mainly exposed in the westernmost Yidun magmatic belt, with A–type granite features. These suggest that the co–collision related magmatism in Indosinian period developed in the central and eastern parts of NSOB while the Yanshan period co–collision related magmatism mainly occurred in the west area. In detail, the earliest magmatism developed in late Permian to Triassic and formed the Jomda–Wei magmatic belt, then magmatic activity migrated eastwards and westwards, forming the Yidun magmatic bellt, the magmatism weakend at the end of late Triassic, until the explosure of the magmatic activity occurred in early Cretaceous in the west NSOB, forming the NE Lhasa magmatic belt. Then the magmatism migrated eastwards and made an impact on the within–plate magmatism in Yidun magmatic belt in late Cretaceous. |
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| Keywords: | intrusions distribution granitoid age and geochemistry Paleozoic and Mesozoic subduction–related magmatic belt Sanjiang orogenic belt |
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