| 兴蒙造山带南缘东段和龙地区Ⅰ型花岗岩锆石U-Pb定年、地球化学特征及其地质意义 |
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| 引用本文： | 关庆彬,李世超,张超,时溢,李鹏川.兴蒙造山带南缘东段和龙地区Ⅰ型花岗岩锆石U-Pb定年、地球化学特征及其地质意义[J].岩石学报,2016,32(9):2690-2706. |
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| 作者姓名： | 关庆彬 李世超 张超 时溢 李鹏川 |
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| 作者单位： | 吉林大学地球科学学院, 长春 130061,吉林大学地球科学学院, 长春 130061,山东理工大学资源与环境工程学院, 淄博 255049,沈阳地质矿产研究所, 沈阳 110034,吉林大学地球科学学院, 长春 130061 |
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| 基金项目： | 本文受国家自然科学基金项目（41272223、41340024）和中国地质调查局项目（12120113098500）联合资助. |
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| 摘 要： | 本文对兴蒙造山带南缘东段和龙地区八家子岩体和勇新岩体进行了岩相学、地球化学、LA-ICP-MS U-Pb定年和Sr-Nd同位素研究,以便制约该区的区域构造演化。锆石测年结果显示,八家子石英闪长岩结晶年龄为257.8±0.9Ma,形成于晚二叠世早期,勇新二长花岗岩的结晶年龄为243.2±1.1Ma和238.5±2.8Ma,形成于中三叠世。八家子石英闪长岩为钠质钙碱系列、偏铝质的Ⅰ型花岗岩类,富集轻稀土(LREEs)和大离子亲石元素(LILEs,Cs、Ba、K和Sr),亏损重稀土(HREEs)和高场强元素(HFSEs,Nb、Ta和P),结合Sr-Nd同位素特征显示其为壳源成因,形成于俯冲环境下,是玄武质下地壳部分熔融的产物。勇新二长花岗岩富硅、铝和钾,为高钾钙碱性系列、偏铝质-弱过铝质的Ⅰ型花岗岩,富集轻稀土(LREEs)及大离子亲石元素(LILEs,Cs、K、Sr),亏损重稀土(HREEs)和高场强元素(HFSEs,Nb、Ta、P和Ti),结合Sr-Nd同位素特征显示其为壳源成因,形成于同碰撞环境下,是玄武质下地壳部分熔融的产物。花岗岩的侵位反映了研究区晚二叠世早期古亚洲洋板块俯冲于华北克拉通之下,中三叠世华北克拉通与兴凯地块碰撞拼合,说明古亚洲洋应闭合于晚二叠世末期-早三叠世期间。
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| 关 键 词： | 兴蒙造山带南缘 Ⅰ型花岗岩 锆石U-Pb测年 地球化学 古亚洲洋 |
| 收稿时间： | 2016/4/11 0:00:00 |
| 修稿时间： | 2016/7/25 0:00:00 |
Zircon U-Pb dating, geochemistry and geological significance of the I-type granites in Helong area, the eastern section of the southern margin of Xing-Meng Orogenic Belt |
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| GUAN QingBin,LI ShiChao,ZHANG Chao,SHI Yi and LI PengChuan.Zircon U-Pb dating, geochemistry and geological significance of the I-type granites in Helong area, the eastern section of the southern margin of Xing-Meng Orogenic Belt[J].Acta Petrologica Sinica,2016,32(9):2690-2706. |
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| Authors: | GUAN QingBin LI ShiChao ZHANG Chao SHI Yi and LI PengChuan |
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| Institution: | College of Earth Science, Jilin University, Changchun 130061, China,College of Earth Science, Jilin University, Changchun 130061, China,School of Resources and Environmental Engineering, Shandong University of Technology, Zibo 255049, China,Shenyang Institute of Geology and Mineral Resource, Shenyang 110034, China and College of Earth Science, Jilin University, Changchun 130061, China |
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| Abstract: | Petrography, geochemical data, LA-ICP-MS zircon U-Pb dating and Sr-Nd isotopic have been obtained from Bajiazi pluton and Yongxin pluton in Helong area, with the aim of constraining the tectonic nature of the eastern section of the southern margin of Xing-Meng Orogenic Belt. LA-ICP-MS zircon U-Pb age data indicate that the quartz diorites from Bajiazi pluton formed during the early period of Late Permian and monzogranites from Yongxin pluton formed during Middle Triassic. Furthermore, Bajiazi quartz diorites belong to calc-alkaline, metaluminous I-type granitoids with feature of Na2O content is higher than K2O. They also show strong enrichment in LREEs and LILEs (Cs, Ba, K and Sr), depletions in HREEs and HFSEs (Nb, Ta and P). Combined the Sr-Nd isotopic data indicate the primary magma for Bajiazi pluton could be mainly derived from partical melting of the mafic lower crust under the tectonic setting of subduction. The Yongxin monzogranites belong to high-K calc-alkaline, metaluminous-weakly peraluminous I-type granitoids with features of rich in SiO2, Al2O3 and K2O. They also show strong enrichment in LREEs and LILEs (Cs, K and Sr), depletions in HREEs and HFSEs (Nb, Ta, Ti and P). Combined the Sr-Nd isotopic data indicate the primary magma for Bajiazi pluton could be mainly derived from partical melting of the mafic lower crust under the tectonic setting of syn-collision. The emplacement timing of Bajiazi pluton and Yongxin pluton reflect the Paleo-Asian oceanic plate had been subducting beneath the eastern section of the northern margin of the North China Plate during the early period of Late Permian, and the collision between North China Plate and Khanka Massif took place at the Middle Triassic, which suggests that the Paleo-Asian Ocean closed is between the end of Late Permian and Early Triassic. |
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| Keywords: | Southern margin of Xing-Meng Orogenic Belt I-type granites Zircon U-Pb dating Geochemistry The Paleo-Asian Ocean |
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