SHRIMP U-Pb dating and Hf isotopic analyses of zircons from the mafic dyke swarms in central Qiangtang area, Northern Tibet

被引：48
作者：
Zhai QingGuo [1 ]
Li Cai [2 ]
Wang Jun [1 ]
Ji ZhanSheng [1 ]
Wang Yong [1 ]
机构：
[1] Chinese Acad Geol Sci, Inst Geol, Beijing 100037, Peoples R China
[2] Jilin Univ, Coll Earth Sci, Changchun 130061, Peoples R China
来源：
CHINESE SCIENCE BULLETIN | 2009年 / 54卷 / 13期
基金：
中国国家自然科学基金;
关键词：
Northern Tibet; Qiangtang; mafic dyke swarm; SHRIMP dating; Hf isotope; ROCKS; AGE;
D O I：
10.1007/s11434-009-0203-6
中图分类号：
O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];
学科分类号：
07 ; 0710 ; 09 ;
摘要：
In the "Central Uplift" of Qiangtang, Northern Tibet, a large scale of mafic dyke swarms extended in E-W direction. Zircon SHRIMP U-Pb dating on two representative samples of diabase dyke yield weighted mean ages of 284 +/- 3 Ma and 302 +/- 4 Ma, respectively, suggesting they emplaced in the Late Carboniferous to Early Permian. Zircon Hf-176/Hf-177 ratios range from 0.282852 to 0.283041, with epsilon (Hf)(t) values of +12.1 to +12.2 and Hf modal (T (DM)) ages of:_440-460 Ma. These data indicate that these mafic dykes were mainly derived from the depleted mantle. In addition, geochemical data suggest that these mafic dyke swarms are of intra-plate origin. Therefore, the mafic dyke swarms represent products during the extensional process associated with the opening of the Paleo-Tethys Ocean in the area.
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页码：2279 / 2285
页数：7
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