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| Zircon U-Pb dating on the Mesozoic volcanic suite from the Qingshan Group stratotype section in eastern Shandong Province and its tectonic significance | |
| 作者姓名： | LING WenLi XIE XianJun LIU XiaoMing & CHENG JianPing Faculty of Earth Sciences China University of Geosciences Wuhan China State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences Wuhan China Key Laboratory of Continental Dynamics Northwest University Xi’an China |
| 作者单位： | LING WenLi1，2，XIE XianJun1，2，LIU XiaoMing1，3 & CHENG JianPing1 1 Faculty of Earth Sciences，China University of Geosciences，Wuhan 430074，China; 2 State Key Laboratory of Geological Processes and Mineral Resources，China University of Geosciences，Wuhan 430074，China; 3 Key Laboratory of Continental Dynamics，Northwest University，Xi’an 710069，China |
| 基金项目： | 国家自然科学基金;教育部创新团队发展基金 |
| 摘 要： | A geochronological study of zircon U-Pb on the volcanic rocks from the stratotype section of the Qingshan Group within the Jiaozhou Basin, eastern Shandong Province, is presented. The zircons were analyzed using the method of in situ ablation of a 193 nm excimer laser system coupled with an up to date ICP-MS system. Among the three formations of the Qingshan Group, zircons recovered from the lowest part of the Houkuang Fm. were dated at 106±2 Ma (95% confidence, the same below), whereas those from the lower and upper parts of the Shiqianzhuang Fm. were given ages of 105±4 Ma and 98±1 Ma, respectively. A spatially decreasing trend for the Mesozoic magmatic timing from west to east in the province is observed through comparing the data of this study with those by previous works on the Qingshan volcanic lavas occurring at western Shandong and within the Yishu fault zone. The Qingshan volcanic rocks are constituent of the 'Shoshonite Province' in East China. Exposed at most provinces of central East China along the Tan-Lu fault and the Yangtze fault zones, these volcanic suites are characterized by shoshonite and high-K calcalkalic rocks in lithology and thought to be correlated with the partial melting of continental mantle in genesis. It is also shown that the Qingshan potassic volcanic suite from eastern Shandong basins is distinctly younger than those from other ar-eas of the shoshonite province. By contrary, ages of the Mesozoic to Cenozoic alkaline basalts, sourced by asthenospheric mantle, from both northern Huaiyan basin and northern Dabie belt along the Tan-Lu fault zone and from the Ningwu, Lishui and Luzong basins along the Yangtze fault zone are observably older than those occurring within eastern Shandong. The revealed temporal and spatial patterns in magmatism for the two types of volcanic suites make an important geochronological con-straint on the Mesozoic to Cenozoic dynamic evolution model of the subcontinental lithosphere in East China. |
| 收稿时间： | 20 May 2005 |
| 修稿时间： | 28 July 2005 |
Zircon U-Pb dating on the Mesozoic volcanic suite from the Qingshan Group stratotype section in eastern Shandong Province and its tectonic significance |
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| Ling?WenLi,Xie?XianJun,Liu?XiaoMing,Cheng?JianPing.Zircon U-Pb dating on the Mesozoic volcanic suite from the Qingshan Group stratotype section in eastern Shandong Province and its tectonic significance[J].Science in China(Earth Sciences),2007,50(6):813-824. | |
| Authors: | Ling WenLi Xie XianJun Liu XiaoMing Cheng JianPing |
| Institution: | 1. Faculty of Earth Sciences, China University of Geosciences, Wuhan 430074, China;State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan 430074, China 2. Faculty of Earth Sciences, China University of Geosciences, Wuhan 430074, China;Key Laboratory of Continental Dynamics, Northwest University, Xi'an 710069, China 3. Faculty of Earth Sciences, China University of Geosciences, Wuhan 430074, China |
| Abstract: | A geochronological study of zircon U-Pb on the volcanic rocks from the stratotype section of the Qingshan Group within the Jiaozhou Basin, eastern Shandong Province, is presented. The zircons were analyzed using the method of in situ ablation of a 193 nm excimer laser system coupled with an up to date ICP-MS system. Among the three formations of the Qingshan Group, zircons recovered from the lowest part of the Houkuang Fm. were dated at 106±2 Ma (95% confidence, the same below), whereas those from the lower and upper parts of the Shiqianzhuang Fm. were given ages of 105±4 Ma and 98±1 Ma, respectively. A spatially decreasing trend for the Mesozoic magmatic timing from west to east in the province is observed through comparing the data of this study with those by previous works on the Qingshan volcanic lavas occurring at western Shandong and within the Yishu fault zone. The Qingshan volcanic rocks are constituent of the ‘Shoshonite Province’ in East China. Exposed at most provinces of central East China along the Tan-Lu fault and the Yangtze fault zones, these volcanic suites are characterized by shoshonite and high-K calcalkalic rocks in lithology and thought to be correlated with the partial melting of continental mantle in genesis. It is also shown that the Qingshan potassic volcanic suite from eastern Shandong basins is distinctly younger than those from other areas of the shoshonite province. By contrary, ages of the Mesozoic to Cenozoic alkaline basalts, sourced by asthenospheric mantle, from both northern Huaiyan basin and northern Dabie belt along the Tan-Lu fault zone and from the Ningwu, Lishui and Luzong basins along the Yangtze fault zone are observably older than those occurring within eastern Shandong. The revealed temporal and spatial patterns in magmatism for the two types of volcanic suites make an important geochronological constraint on the Mesozoic to Cenozoic dynamic evolution model of the subcontinental lithosphere in East China. Supported by the National Natural Science Foundation of China (Grant No. 40133020) and Innovation Term Grant of Ministry of Education of China |
| Keywords: | Mesozoic volcanic suite Qingshan Group stratotype section zircon U-Pb tectonic significance |
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