| Petrogenesis of Kejie Granite in the Northern Changning-Menglian Zone, Western Yunnan: Constraints from Zircon U-Pb Geochronology,
Geochemistry and Hf Isotope |
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| 作者姓名： | NIE Fei DONG Guochen MO Xuanxue WANG Xi FAN Wenyu DONG Meiling and ZHU Huaping |
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| 作者单位： | 1 Chengdu Institute of Geology and Mineral Resource, Chengdu 610081, China
2 School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China
3 Earthquake Administration of Shanxi Provence, Taiyuan 030021, China |
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| 基金项目： | This study was financially supported by the Programme of the China Geological Survey (No.1212011120608, No.1212011220907), the National Key Projects for Basic Research of China (No.2009CB421002, No.2011CB403102), NSF of China (No. 40672044), Program for Changjiang Scholars, Innovative Research Team in University (No.IRT1083) and 111 project (No.B07011). |
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| 摘 要： | The Kejie pluton is located in the north of the Changning-Menglian suture zone. The rock types are mainly biotite-granite. Zircon LA-ICP-MS U-Pb dating indicates that the Kejie pluton emplaced at about 80–77 Ma, Late Cretaceous. The Kejie pluton samples are characterized by high SiO2(71.68%–72.47%), K2O(4.73%–5.54%), total alkali(K2O + Na2O = 8.21%–8.53%), K2O/Na2O ratios(1.36–1.94) and low P2O5(0.13%–0.17%), with A/CNK of 1.025–1.055; enriched in U, Th, and K, depleted in Ba, Nb, Sr, Ti, P and Eu. They are highly fractionated, slightly peraluminous I-type granite. The two samples of the Kejie pluton give a large variation of εHf(t) values(-5.04 to 1.96) and Hf isotope crustal model ages of 1.16–1.5 Ga. Zircon Hf isotopes and zircon saturation temperatures of whole-rock(801°C–823°C) show that the mantle-derived materials maybe have played a vital role in the generation of the Kejie pluton. The Kejie pluton was most likely generated in a setting associated with the eastward subduction of the neo-Tethys ocean, where intrusion of mantle wedge basaltic magmas in the crust caused the anatexis of the latter, forming hybrid melts, which subsequently experienced high-degree fractional crystallization.
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| 关 键 词： | 锆石U-Pb年代学 黑云母花岗岩 Hf同位素 地球化学 LA-ICP-MS 岩体侵位 成因 滇西 |
| 收稿时间： | 2013/11/11 0:00:00 |
| 修稿时间： | 2014/2/24 0:00:00 |
Petrogenesis of Kejie Granite in the Northern Changning-Menglian Zone,Western Yunnan： Constraints from Zircon U-Pb Geochronology,Geochemistry and Hf Isotope |
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| Authors: | NIE Fei ;DONG Guochen ;MO Xuanxue ;WANG Xia ;FAN Wenyu ;DONG Meiling ;ZHU Huaping |
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| Institution: | [1]Chengdu Institute of Geology and MineralResource, Chengdu 610081, China; [2]School of Earth Sciences and Resources, China University ofGeosciences, Beijing 100083, China; [3]Earthquake Administration of Shanxi Provence, Taiyuan 030021, China |
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| Abstract: | The Kejie pluton is located in the north of the Changning‐Menglian suture zone. The rock types are mainly biotite‐granite. Zircon LA‐ICP‐MS U‐Pb dating indicates that the Kejie pluton emplaced at about 80–77 Ma, Late Cretaceous. The Kejie pluton samples are characterized by high SiO2 (71.68%–72.47%), K2O (4.73%–5.54%), total alkali (K2O + Na2O = 8.21%–8.53%), K2O/Na2O ratios (1.36–1.94) and low P2O5 (0.13%–0.17%), with A/CNK of 1.025–1.055; enriched in U, Th, and K, depleted in Ba, Nb, Sr, Ti, P and Eu. They are highly fractionated, slightly pet aluminous I‐type granite. The two samples of the Kejie pluton give a large variation of εHf(t) values (–5.04 to 1.96) and Hf isotope crustal model ages of 1.16–1.5 Ga. Zircon Hf isotopes and zircon saturation temperatures of whole‐rock (801°C–823°C) show that the mantle‐derived materials maybe have played a vital role in the generation of the Kejie pluton. The Kejie pluton was most likely generated in a setting associated with the eastward subduction of the neo‐Tethys ocean, where intrusion of mantle wedge basaltic magmas in the crust caused the anatexis of the latter, forming hybrid melts, which subsequently experienced high‐degree fractional crystallization. |
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| Keywords: | Zircon U-Pb dating and Hf isotope geochemistry highly fractionated 1-type granite Kejiepluton neo-Tethys ocean |
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