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.pdf

第34卷第2~3期
地质通报
Vol 34. Nos2-3
2015年3月
GEOLOGICAL BULLETIN OF CHINA
Mar.,2015
西藏罗布莎群中火山岩夹层LA-ICP-ーMS錯石
U-Pb年龄及其意义
孔明',江万2,刘成东,李晓雄3,杨云汉',叶培盛2
KONG Ming JIANG Wan, LIU Chengdong, LI Xiaoxiong, YANG Yunhan
YE Peisheng
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
1. State Key Laboratory Breeding Base of Nuclear Resources and Enuironment, East China Institute of Technology
Nanchang 330013, China
2. Institute ofgeomechanics, CAGS, Beijing 100081, China;
3. State Key Laboratory of Geological Processes and Mineral Resources, School of Earth Science and Mineral Resources
China University of Geoscienees, Beijing 100083, China
摘要:针对泽当西郊贡巴?北坡剖面罗布莎群砾岩下部厚约15n的火山岩夹层进行结石定年,测试结果表明,该火山岩LA
ICP-MS错石UーPb年龄为18.70.2Ma,罗布莎群下伏花岗岩LA-ICPーMS石U-Pb年龄为29.9士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国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,其时空分布特征与网
底斯带中新世钾质一超钾质火山活动具有显著的相似性。
关键词:LA-ICP-MS锆石U-Pb年龄;火山岩;罗布莎群砾岩;泽当
中图分类号:P58814;P597:3文献标志码:A文章编号:1671-2552(2015)02/03-0328-09
Kong M, Jiang W, Liu C D, Li X X, Yang Y H, Ye P S. LA-ICP-MS zircon U-pb age of the tufts from the Luobusha con
glomerates in southeast Tibet and its implications. Geological Bulletin of China, 2015, 34(2/3): 328-336
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 tuas 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 conglomer
ates is 29. t0.. The existence of the uff documents a volcan activity developed at 18.7*.2MA.In combination with echr-
nologic 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
Key words: LA-ICP-MS zircon U-pb age; volcanic rock; Luobusha conglomerates; Zetang
收稿日期:2014-12-04;修订日期:2014-12-31
资助项目:中国地质调查局项目(编号:1212011220937、1212011120182
作者简介:孔明(1989),男,在读硕士生,地质学专业。E-mail!ongoing890163.com
通讯作者:江万(1969-),男,博士,研究员,从事岩石学与大地构造研究。E-mail;namcor@sina.cn