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| Keywords | |
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Northern Tibet |
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Qiangtang |
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mafic dyke swarm |
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SHRIMP dating |
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Hf isotope |
| Authors | |
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ZHAI QingGuo |
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LI Cai |
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WANG Jun |
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JI ZhanSheng |
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WANG Yong |
| PubMed | |
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Article by ZHAI QingGuo |
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Article by LI Cai |
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Article by WANG Jun |
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Article by JI ZhanSheng |
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Article by WANG Yong |
SHRIMP U-Pb dating and Hf isotopic analyses of zircons from the mafic dyke swarms in central Qiangtang area, Northern Tibet
ZHAI QingGuo1, LI Cai2, WANG Jun1, JI ZhanSheng1 &|WANG Yong1
1 Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China;
2 College of Earth Sciences, Jilin University, Changchun 130061, China
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 Carbonif-erous to Early Permian. Zircon 176Hf/177Hf ratios range from 0.282852 to 0.283041, with εHf(t) values of +12.1 to +12.2 and Hf modal (TDM) 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.
Supported by the National Natural Science Foundation of China (Grants Nos. 40872146 and 40672147) and China Geological Survey (Grant No. 1212010561605)