| 辽东半岛～2．2 Ga 岩浆事件及其地质意义 |
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| 引用本文： | 陈斌,李壮,王家林,张璐,鄢雪龙.辽东半岛～2．2 Ga 岩浆事件及其地质意义[J].吉林大学学报(地球科学版),2016,46(2):303-320. |
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| 作者姓名： | 陈斌 李壮 王家林 张璐 鄢雪龙 |
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| 作者单位： | 合肥工业大学资源与环境工程学院,合肥,230009;北京大学地球与空间科学学院/造山带与地壳演化教育部重点实验室,北京,100871 |
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| 基金项目： | 科技部“973”项目(2012CB416603)；国家自然科学基金重点项目(90914001)；北京大学开放测试基金(0000010541)；吉林大学大学生创新性实验计划项目(2010C61164) |
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| 摘 要： | 本文报道了辽东半岛古元古代胶—辽—吉活动带内辽河群变质火山岩和辽吉花岗岩的锆石LA-ICP-MS U-Pb年代学和地球化学数据。变质安山岩的锆石具典型的岩浆振荡环带结构和较高的Th/U值(0.5),锆石U-Pb年龄为(2 182±6)Ma和(2 229±22)Ma,该年龄可代表安山岩的形成年龄。辽吉花岗岩的锆石同样具有典型的岩浆振荡环带结构和较高的Th/U值(0.3),锆石U-Pb年龄为(2 199±10)Ma,代表花岗岩的侵位时代,在误差范围内与辽河群火山岩喷发时代一致,表明辽吉花岗岩并不是辽河群的基底,二者可能为同一次岩浆作用过程的产物。辽东半岛~2.2Ga岩浆事件的识别及性质,对于正确认识古元古代胶—辽—吉活动带的属性至关重要。结合前人有关辽东半岛前寒武纪岩石的研究成果,本文研究认为胶—辽—吉活动带的形成演化可能与弧-陆碰撞有关。
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| 关 键 词： | 锆石LAICPMS定年 2.2Ga 岩浆事件 辽东半岛 胶-辽-吉活动带 辽吉花岗岩 辽河群变质火山岩 |
Liaodong Peninsula ~2 .2 Ga Magmatic Event and Its Geological Significance |
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| Chen Bin,Li Zhuang,Wang Jialin,Zhang Lu,Yan Xuelong.Liaodong Peninsula ~2 .2 Ga Magmatic Event and Its Geological Significance[J].Journal of Jilin Unviersity:Earth Science Edition,2016,46(2):303-320. |
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| Authors: | Chen Bin Li Zhuang Wang Jialin Zhang Lu Yan Xuelong |
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| Abstract: | The geochronology and geochemical studies were carried out on the Paleoproterozoic meta‐volcanic rocks and the Liaoji granite from Jiao Liao Ji mobile belt in North China craton to understand the ~2 .2 Ga magmatic event and its geodynamic setting .The zircon LA ICP MS U Pb analyses on the meta‐andesites yield 207 Pb/206 Pb ages of (2 182 ± 6) Ma and (2 229 ± 22) Ma .These zircons exhibit oscillatory and sector‐zoning and high Th/U ratios (>0 .5) ,the typical magmatic origin ;thus the ages probably represent the formation ages of the protolith of the meta‐volcanic rocks .The zircons from the Paleopr oterozoic Liaoji granite share the similar magmatic characteristics with those from the meta‐volcanic rocks ,e .g .,oscillatory and sector‐zoning ,and high Th/U ratios (>0 .3) .The zircon U Pb isotopic dating by using the LA ICP MS method on the Paleoproterozoic Liaoji granite reveals that they formed at (2 199 ± 10 ) Ma , which are regionally comparable to those of the Paleoproterozoic meta‐volcanic rocks .Our age data suggest a synchronism for the two rock units ,rather than that the Paleopreoterozoic Liaoji granites were the basement of Liaohe Group volcanic rocks as considered previously . T he recognition and the nature of the ~ 2 .2 Ga magmatic event in Liaodong Peninsula are critical for understanding the evolution of Jiao Liao Ji mobile belt . Our new data , coupled with recent studies on lithology ,metamorphism ,geochemistry ,and geochronology of Archean‐Paleoproterozoic basement rocks ,support the Paleoproterozoic arc‐continent collision model . |
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| Keywords: | zircon LA ICP MS dating ~2 2 Ga magmatic event Liaodong Peninsula Jiao Liao Ji mobile belt Liaoji granite meta-volcanic rocks of Liaohe Group |
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