| Qingbaikouan and Crygenian in South China: Constraints by SHRIMP Zircon U-Pb dating |
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| 作者姓名： | GAO Linzhi DING Xiaozhong YIN Chongyu ZHANG Chuanheng and Frank R. ETTENSOHN |
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| 作者单位： | 1 Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China;2 China University of Sciences, Beijing 100083, China;3 Department of Earth and Environment Sciences, University of Kentucky, Lexington, KY 40506-0053, USA |
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| 基金项目： | This study was supported by the China Geological Survey (CGS) and IGMA 5000 (Grant No. 12120113013900), and the Ministry of Science and Technology (MST) (Grant No., 2011FY120100). Project supported by the National Science Foundation of China (Grant No. 41372038). |
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| 摘 要： | The Qingbaikouan System is the lowest unit of the Neoproterozoic Erathem in Chinese stratigraphic succession,and it now provides a precise geochronological framework and geological time scale for mapping and stratal correlation in China.However,a sensitive high-resolution ion microprobe （SHRIMP） U-Pb zircon age date （1368±12 Ma） obtained from a bentonite in the Qingbaikouan Xiamaling Formation indicates that it belongs to the Mesoproterozoic Erathem instead.This change is a milestone in understanding the Precambrian Stratigraphic Time Scale in China,and it has had great influence on Precambrian correlations in Asia.Otherwise,a large amount of geochronological work has been done in the ＂Jiangnan Orogen Belt＂ of South China,and new isotopic data have redefined the traditional recognition of metamorphosed Mesoproterozoic strata from the Sibao orogeny to the Neoproterozoic Erathem.Based on SHRIMP zircon U-Pb age data,the authors regard the Sibao orogeny （equal to the Wuling orogeny） as a movement at ca 820 Ma,meaning that the Sibao orogeny was not equivalent to the Grenvillian orogeny.Finally,we report here the first SHRIMP U-Pb age of the boundary between the top of the Qingbaikouan Gongdong Formation （786.8±5.6 Ma） and the bottom of the Chang＇an （diamictite） Formation （778.4±5.2 Ma）,which is the age of the lowest diamictite of the Nanhuan System in China.
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| 关 键 词： | SHRIMP锆石U-Pb定年 中国南方 SHRIMP锆石U-Pb年龄 地质年代学 造山运动 江南造山带 中元古代地层 新元古代 |
| 收稿时间： | 2012/12/12 0:00:00 |
| 修稿时间： | 2013/5/27 0:00:00 |
Qingbaikouan and Crygenian in South China： Constraints by SHRIMP Zircon U-Pb dating |
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| Authors: | GAO Linzhi DING Xiaozhong YIN Chongyu ZHANG Chuanheng Frank R ETTENSOHN |
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| Institution: | [1]Institute of Geology, Chinese Academy of Geological Sciences, Beijing 10003 7, China [2]China University of Sciences, Beijing 100083, China [3]Department of Earth and Environment Sciences, University of Kentucky, Lexington, KY 40506-0053, USA |
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| Abstract: | The Qingbaikouan System is the lowest unit of the Neoproterozoic Erathem in Chinese stratigraphic succession, and it now provides a precise geochronological framework and geological time scale for mapping and stratal correlation in China. However, a sensitive high‐resolution ion microprobe (SHRIMP) U‐Pb zircon age date (1368±12 Ma) obtained from a bentonite in the Qingbaikouan Xiamaling Formation indicates that it belongs to the Mesoproterozoic Erathem instead. This change is a milestone in understanding the Precambrian Stratigraphic Time Scale in China, and it has had great influence on Precambrian correlations in Asia. Otherwise, a large amount of geochronological work has been done in the “Jiangnan Orogen Belt” of South China, and new isotopic data have redefined the traditional recognition of metamorphosed Mesoproterozoic strata from the Sibao orogeny to the Neoproterozoic Erathem. Based on SHRIMP zircon U‐Pb age data, the authors regard the Sibao orogeny (equal to the Willing orogeny) as a movement at ca 820 Ma, meaning that the Sibao orogeny was not equivalent to the Grenvillian orogeny. Finally, we report here the first SHRIMP U‐Pb age of the boundary between the top of the Qingbaikouan Gongdong Formation (786.8±5.6 Ma) and the bottom of the Chang'an (diamictite) Formation (778.4±5.2 Ma), which is the age of the lowest diamictite of the Nanhuan System in China. |
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| Keywords: | Neoproterozoic Nanhuan System SHRIMP U-Pb Geochronology |
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