| 西藏罗布莎群中火山岩夹层LA-ICP-MS 锆石U-Pb 年龄及其意义 |
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| 引用本文： | 孔明,江万,刘成东,李晓雄,杨云汉,叶培盛.西藏罗布莎群中火山岩夹层LA-ICP-MS 锆石U-Pb 年龄及其意义[J].地质通报,2015,34(203):328-336. |
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| 作者姓名： | 孔明 江万 刘成东 李晓雄 杨云汉 叶培盛 |
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| 作者单位： | 1.东华理工大学省部共建核资源与环境国家重点实验室培育基地，江西南昌330013；2.中国地质科学院地质力学研究所，北京100081；3.地质过程与矿产资源国家重点实验室，中国地质大学地球科学与资源学院，北京100083 |
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| 基金项目： | 中国地质调查局项目（编号：1212011220937、1212011120182） |
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| 摘 要： | 针对泽当西郊贡巴日北坡剖面罗布莎群砾岩下部厚约15m的火山岩夹层进行锆石定年，测试结果表明，该火山岩LA-ICP-MS 锆石U-Pb年龄为18.7±0.2Ma，罗布莎群下伏花岗岩LA-ICP-MS锆石 U-Pb年龄为29.9±0.4Ma。据此认为，罗布莎群砾岩初始沉积时代约为20Ma前。火山岩的出现表明，中新世布尔迪加尔期罗布莎群发育一期火山活动，结合前人研究认为，沿雅鲁藏布江结合带的狭长范围内自西向东发育一期火山活动，代表雅鲁藏布江缝合带的一次活化，其时空分布特征与冈底斯带中新世钾质—超钾质火山活动具有显著的相似性。
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| 关 键 词： | LA-ICP-MS锆石U-Pb年龄 火山岩 罗布莎群砾岩 泽当 |
LA-ICP-MS zircon U-Pb age of the tuffs from the Luobusha conglomerates in southeast Tibet and its implications |
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| KONG Ming,JIANG Wan,LIU Chengdong,LI Xiaoxiong,YANG Yunhan,YE Peisheng.LA-ICP-MS zircon U-Pb age of the tuffs from the Luobusha conglomerates in southeast Tibet and its implications[J].Geologcal Bulletin OF China,2015,34(203):328-336. |
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| Authors: | KONG Ming JIANG Wan LIU Chengdong LI Xiaoxiong YANG Yunhan YE Peisheng |
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| Institution: | 1. State Key Laboratory Breeding Base of Nuclear Resources and Environment, East China Institute of Technology,Nanchang 330013, China; 2. Institute of Geomechanics, CAGS, Beijing 100081, China; 3. State Key Laboratory of Geological Processes and Mineral Resources, School of Earth Science and Mineral Resources, China University of Geosciences, Beijing 100083, China |
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| Abstract: | The age of the felsic tuff interbedded with the Luobusha conglomerates in western Zetang County is reported for the first time in this paper. LA-ICP-MS zircon U-Pb analysis shows that the tuffs were formed at 18.7±0.2Ma, and hence the time of the initial deposition should be about 20Ma, whereas the LA-ICP-MS zircon U-Pb age of granite underlying the Luobusa conglomerates is 29.9±0.4Ma. The existence of the tuff documents a volcanic activity developed at 18.7±0.2Ma. In combination with geochronologic data from previous work, the authors hold that volcanic activities were developed all along the Yarlung Zangbo suture zone, meaning the re-activation of the suture zone, which is remarkably similar to the potassic-ultrapotassic volcanism along the Gangdise zone in time and space. |
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| Keywords: | LA-ICP-MS zircon U-Pb age volcanic rock Luobusha conglomerates Zetang |
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