| Ordovician Granitoids and Silurian Mafic Dikes in the Western Kunlun Orogen, Northwest China: Implications for Evolution of the Proto-Tethys |
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| 作者姓名： | ZHANG Qichao WU Zhenhan LI Shan LI Kan LIU Zhiwei ZHOU Qing |
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| 作者单位： | 1 Chinese Academy of Geological Sciences, Beijing 100037, China;2 Key Laboratory of Deep-Earth Dynamics, Ministry of Natural Resources, Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China;3 Xi’an Institute of Geology and Mineral Resources, Chinese Geological Survey, Xi’an 710054, China; 4 Chengdu Institute of Geology and Mineral Resources, Chinese Geological Survey, Chengdu 610081, China |
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| 基金项目： | funded by the Strategic Priority Research Program of Chinese Academy of Sciences,Grant No.XDA20070304;the Fundamental Research Funds for the Chinese Academy of Geological Sciences(YYWF201601);projects of China Geological Survey(DD20160004,20160083-1,12120115000801,121201101000150014);the National Natural Science Foundation of China(grant 41772232) |
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| 摘 要： | The western Kunlun orogen in the northwest Tibet Plateau is related to subduction and collision of Proto-and Paleo-Tethys from early Paleozoic to early Mesozoic. This paper presents new LA-ICPMS zircon U-Pb ages and Lu-Hf isotopes, whole-rock major and trace elements, and Sr–Nd isotopes of two Ordovician granitoid plutons(466–455 Ma) and their Silurian mafic dikes(～436 Ma) in the western Kunlun orogen. These granitoids show peraluminous high-K calcalkaline characteristics, with(87Sr/86Sr)_i value of 0.7129–0.7224, εNd(t) values of -9.3 to -7.0 and zircon εHf(t) values of -17.3 to -0.2, indicating that they were formed by partial melting of ancient lower-crust(metaigneous rocks mixed with metasedimentary rocks) with some mantle materials in response to subduction of the Proto-Tethyan Ocean and following collision. The Silurian mafic dikes were considered to have been derived from a low degree of partial melting of primary mafic magma. These mafic dikes show initial 87Sr/86Sr ratios of 0.7101–0.7152 and εNd(t) values of -3.8 to -3.4 and zircon εHf(t) values of -8.8 to -4.9, indicating that they were derived from enriched mantle in response to post-collisional slab break-off. Combined with regional geology, our new data provide valuable insight into late evolution of the Proto-Tethys.
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| 关 键 词： | High-K CALC-ALKALINE GRANITOIDS mafic DIKES Western KUNLUN OROGEN Proto-Tethys |
| 收稿时间： | 2018/8/16 0:00:00 |
| 修稿时间： | 2018/10/25 0:00:00 |
Ordovician Granitoids and Silurian Mafic Dikes in the Western Kunlun Orogen,Northwest China:Implications for Evolution of the Proto-Tethys |
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| Authors: | ZHANG Qichao WU Zhenhan LI Shan LI Kan LIU Zhiwei ZHOU Qing |
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| Abstract: | The western Kunlun orogen in the northwest Tibet Plateau is related to subduction and collision of Proto‐ and Paleo‐Tethys from early Paleozoic to early Mesozoic. This paper presents new LA‐ICPMS zircon U‐Pb ages and Lu‐Hf isotopes, whole‐rock major and trace elements, and Sr–Nd isotopes of two Ordovician granitoid plutons (466–455 Ma) and their Silurian mafic dikes (～436 Ma) in the western Kunlun orogen. These granitoids show peraluminous high‐K calc‐alkaline characteristics, with (87Sr/86Sr)i value of 0.7129–0.7224, εNd(t) values of –9.3 to –7.0 and zircon εHf(t) values of –17.3 to –0.2, indicating that they were formed by partial melting of ancient lower‐crust (metaigneous rocks mixed with metasedimentary rocks) with some mantle materials in response to subduction of the Proto‐Tethyan Ocean and following collision. The Silurian mafic dikes were considered to have been derived from a low degree of partial melting of primary mafic magma. These mafic dikes show initial 87Sr/86Sr ratios of 0.7101–0.7152 and εNd(t) values of –3.8 to –3.4 and zircon εHf(t) values of –8.8 to –4.9, indicating that they were derived from enriched mantle in response to post‐collisional slab break‐off. Combined with regional geology, our new data provide valuable insight into late evolution of the Proto‐Tethys. |
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| Keywords: | High‐K calc‐alkaline granitoids mafic dikes Western Kunlun Orogen Proto‐Tethys |
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