| 华夏地块龙泉地区发现亚洲最古老的锆石 |
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| 关键词:zircon Hadean Longquan Cathaysia Block |
| 基金项目:中国地质调查局工作项目“华东基础地质综合调查与片区总结”(编号: 1212011220542);国家自然科学基金项目(编号: 41002024; 41202141) |
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| The Discovery of the Asian Oldest Zircons in Longquan, Cathaysia Block |
| At present, zircons are the only residual material of the Hadean crust, and constitute a crucial clue to understanding the early crustal evolution. Rencently, we found the two ~4100 Ma detrital zircons from a Paleozoic quartzite in the Longquan area of the Cathaysia Block, through SHRIMP zircon data. One zircon (207Pb/206Pb age of 4127±4 Ma) shows normal oscillatory zonation and constant mantle-like oxygen isotope ratios (δ18O = 5.8‰ to 6.0‰), and might have crystallized in ancient mantle-derived magmas or partial melts of primitive crust. Obviously, this is the oldest age in the reported zircon ages of Asia. The other zircon grain has a ~4100 Ma magmatic core surrounded by a ~4070 Ma metamorphic mantle. The 4070 Ma indicates the most reliable metamorphic age of the earth. Outside the mantle, two overgrowth bands are 3800~3600 Ma, implying that the magmatic core (crust) underwent complex evolutions after ~4100Ma. These data demonstate the diversity of the Earth’s earliest crustal nature and tectonic setting, and provide crucial evidence for us to understand the earliest crustal evolution. |
| XING Guang-fu,YANG Zhu-liang,CHEN Zhi-hong,JIANG Yang,HONG Wen-tao,JIN Guo-dong,YU Ming-gang,ZHAO Xi-lin,DUAN Zheng.2015.The Discovery of the Asian Oldest Zircons in Longquan, Cathaysia Block[J].Acta Geoscientica Sinica,36(4):395-402. |
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