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东准噶尔西缘晚古生代火山岩的锆石U-Pb年龄和Hf同位素特征及构造意义
引用本文:史基安,唐相路,张顺存,张宏福,肖燕. 东准噶尔西缘晚古生代火山岩的锆石U-Pb年龄和Hf同位素特征及构造意义[J]. 地质科学, 2012, 0(4): 955-979
作者姓名:史基安  唐相路  张顺存  张宏福  肖燕
作者单位:1. 中国科学院油气资源研究重点实验室 兰州 730000;2. 中国科学院研究生院 北京 100049;3. 中国科学院地质与地球物理研究所 北京 100029
摘    要:白碱沟和帐篷沟剖面位于东准噶尔西缘,出露有大量古生代火山岩,是研究东准噶尔古生代火山岩及构造演化的有利区域.本文利用LA-MC-ICP-MS锆石U-Pb定年法和Hf同位素系统对该区中的玄武岩、玄武质安山岩、流纹岩、角斑岩以及少量的凝灰岩和正长斑岩进行了地质年代学研究,认为它们形成于早泥盆世至晚石炭世之间(400~307...

关 键 词:中亚造山带  东准噶尔  锆石U-Pb定年  Hf同位素  年轻地壳  岛弧  陆壳增生
收稿时间:2012-06-02
修稿时间:2012-06-02;

Zircon U-Pb age and Hf isotopic systematics of Late Paleozoic volcanic from the western margin of east Junggar and tectonic implication
Shi Ji'an,Tang Xianglu,Zhang Shuncun,Zhang Hongfu,Xiao Yan. Zircon U-Pb age and Hf isotopic systematics of Late Paleozoic volcanic from the western margin of east Junggar and tectonic implication[J]. Chinese Journal of Geology, 2012, 0(4): 955-979
Authors:Shi Ji'an  Tang Xianglu  Zhang Shuncun  Zhang Hongfu  Xiao Yan
Affiliation:1. Key Laboratory of Petroleum Resources Research,Institute of Geology and Geophysics,Chinese Academy of Sciences,Lanzhou 730000;2. Graduate University of Chinese Academy of Sciences,Beijing 100049;3. Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029
Abstract:Two sections,namely Baijiangou and Zhangpenggo,in the western margin of east Junggar,where expose a large number of Paleozoic volcanic rocks,are the favorable areas to study the tectonic evolution of the east Junggar.LA-MC-ICP-MS zircon U-Pb dating and Hf isotopic systematics study of igneous rocks(basalt,basaltic andesite,rhyolite and keratophyre with minor tuff and syenite-porphyry),using geochrony technology,suggests that they were formed during Early Devonian to Late Carboniferous(400~307 Ma).Basalts and basaltic andesites are more likely output as dikes,and they display age-range from 435 Ma to 300 Ma and show positive εHf(t) values(+0.7~+15.4),which suggests that the east Junggar terrane is controled by juvenile crust and that the Precambrian crystalline rocks must be very limited,if there is any.The Zhangpenggou rhyolite and keratophyre,zircon U-Pb ages of 332 Ma and 336 Ma respectively,were formed in a volcanic arc environment or a environment which was mixed with part of island arc.The Baijiangou syenite-porphyries with positive εHf(t) values in Late Carboniferous(307 Ma and 315 Ma)indicate a vertical accretion of crustal materials.The Baijiangou rhyolites which show positive εHf(t)values and zircon U-Pb ages of 315 Ma and 323 Ma suggests a lateral accretion of crustal materials.Therefore,the east Junggar is mainly accretionary prism undering extensional settings of post-collisional period,and it's considered today to be a Paleozoic Mariana-type intra-oceanic island arc.
Keywords:Central Asian orogenic belt  East Junggar  Zircon U-Pb dating  Hf isotopic  Juvenile crust  Island arc  Continental growth
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