| 扬子陆块北缘西大别地区定远组双峰式火山岩U-Pb年代学及其地质构造意义 |
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| 引用本文： | 朱江,彭三国,彭练红,许珂,张闯,刘锦明,王祥东.扬子陆块北缘西大别地区定远组双峰式火山岩U-Pb年代学及其地质构造意义[J].地球科学,2019,44(2):355-365. |
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| 作者姓名： | 朱江 彭三国 彭练红 许珂 张闯 刘锦明 王祥东 |
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| 作者单位： | 1.中国地质调查局武汉地质调查中心, 湖北武汉 430205 |
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| 基金项目： | 中国地质调查局项目121201009000150013中国地质调查局项目121201009000160902 |
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| 摘 要： | 西大别地区定远组由浅变质的酸性火山岩(流纹岩和流纹质凝灰岩)和基性火山岩组成,二者在空间上互层产出,具典型的双峰式火山岩系组合特征,为认识南秦岭-大别造山带及扬子陆块北缘前寒武纪物质组成和地质演化提供了极佳的研究对象.通过对2件变流纹岩、1件变流纹质晶屑凝灰岩和1件变基性火山岩样品进行LA-ICP-MS锆石原位U-Pb测年,获得其成岩年龄分别为737±5Ma、740±3Ma、740±5Ma和739±6Ma.结果表明,定远组双峰式火山岩系形成时代并非前人认识的古生代,而是新元古代约740Ma.定远组与红安岩群双峰式火山建造形成时间基本一致,指示了西大别地区新元古代一次重要的拉张构造-岩浆事件,可能形成于大陆边缘裂谷环境.扬子陆块北缘武当-随枣-大别地区新元古代800～720Ma岩浆活动广泛且强烈,其峰期为755～730Ma,可能是对Rodinia超大陆裂解事件的响应.
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| 关 键 词： | 双峰式 火山岩 地质年代学 新元古代 构造背景 大别山 地球化学 |
| 收稿时间： | 2018-12-20 |
Geochronology of Bimodal Volcanic Rocks from Dingyuan Formation in Western Dabie Orogen,Central China: Implications for Extension during Breakup of Rodinia |
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| Zhu Jiang,Peng Sanguo,Peng Lianhong,Xu Ke,Zhang Chuang,Liu Jinming,Wang Xiangdong.Geochronology of Bimodal Volcanic Rocks from Dingyuan Formation in Western Dabie Orogen,Central China: Implications for Extension during Breakup of Rodinia[J].Earth Science-Journal of China University of Geosciences,2019,44(2):355-365. |
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| Authors: | Zhu Jiang Peng Sanguo Peng Lianhong Xu Ke Zhang Chuang Liu Jinming Wang Xiangdong |
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| Institution: | (Wuhan Center,China Geological Survey,Wuhan 430205, China;Research Center of Granitic Diagenesis and Mineralization,China Geological Survey,Wuhan 430205, China;College of Resources and Environment,Yangtze University,Wuhan 430100, China;Sixth Geological Brigade,Hubei Geological Bureau,Xiaogan 432000, China) |
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| Abstract: | In-situ zircon U-Pb ages are reported for the meta-bimodal volcanic suite of rhyolites and basalts from the Dingyuan Formation in the western Dabie orogen. The rhyolite, the rhyolitic tuff, and the basalt yield zircon U-Pb ages of 737±5 Ma (1σ, MSWD=0.02), 740±3 Ma (1σ, MSWD=0.07), 740±5 Ma (1σ, MSWD=0.07) and 739±6 Ma (1σ, MSWD=0.07), respectively, indicating that the bimodal suite was erupted during the Neoproterozoic. Intensive magmatic rocks were widespread throughout the South Qinling, Suizao, western Dabie and eastern Dabie areas during 755 to 730 Ma, such as the Yaolinghe Group, the Suixian Group, the Hong'an Group and the Dingyuan Formation. These igneous rocks show peak ages at ca.740 Ma, indicating a continental rift extensional setting in the northern margin of the Yangtze Block during the breakup of supercontinent Rodinia. |
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| Keywords: | bimodal volcanic rock geochronology Neoproterozoic tectonic setting Dabie orogen geochemistry |
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