| 扬子地块西缘河口群的时代:来自火山岩锆石LA-ICP-MS U-Pb年龄的证据 |
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| 引用本文： | 王冬兵,孙志明,尹福光,王立全,王保弟,张万平.扬子地块西缘河口群的时代:来自火山岩锆石LA-ICP-MS U-Pb年龄的证据[J].地层学杂志,2012(3):630-635. |
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| 作者姓名： | 王冬兵 孙志明 尹福光 王立全 王保弟 张万平 |
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| 作者单位： | 成都地质矿产研究所 |
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| 基金项目： | 国家重点研究发展计划项目(2009CB421003);中国地质调查局地质矿产调查评价专项项目(1212011085119,1212011085147,1212011121259)联合资助 |
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| 摘 要： | 扬子地块西缘的河口群长期以来被认为是早元古代的火山—沉积地层,这种认识缺乏高精度同位素年龄的支持。为精确标定河口群的时代,采用激光剥蚀等离子体质谱(LA-ICP-MS)对川西南拉拉铜矿区河口群中的石英角斑岩进行锆石U-Pb定年。结果表明所有锆石均为岩浆锆石,单点分析结果均为谐和年龄,锆石207Pb/206Pb加权平均年龄为1722±25Ma(2σ,MSWD=0.5,n=11)。由此认为河口群浅变质火山—沉积岩系的精确沉积时代为1722±25Ma,为早元古代晚期的火山—沉积地层。
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| 关 键 词： | 年代地层学 锆石U-Pb年龄 LA-ICP-MS 河口群 早元古代 扬子地块 |
GEOCHRONOLOGY OF THE HEKOU GROUP ON THE WESTERN MARGIN OF THE YANGTZE BLOCK:EVIDENCE FROM ZIRCON LA-ICP-MS U-PB DATING OF VOLCANIC ROCKS |
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| WANG Dong-bing,SUN Zhi-ming,YIN Fu-guang,WANG Li-quan WANG Bao-di and ZHANG Wan-ping.GEOCHRONOLOGY OF THE HEKOU GROUP ON THE WESTERN MARGIN OF THE YANGTZE BLOCK:EVIDENCE FROM ZIRCON LA-ICP-MS U-PB DATING OF VOLCANIC ROCKS[J].Journal of Stratigraphy,2012(3):630-635. |
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| Authors: | WANG Dong-bing SUN Zhi-ming YIN Fu-guang WANG Li-quan WANG Bao-di and ZHANG Wan-ping |
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| Institution: | Chengdu Institute of Geology and Mineral Resources,Chengdu610081 |
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| Abstract: | The Hekou Group on the western margin of the Yangtze Block has long been considered to be Paleoproterozoic volcanic-sedimentary strata.However,high-quality isotopic age in support of this inference is lacking.To determine the age of the Hekou Group,we carried out in-situ zircon LA-ICP-MS U-Pb dating of volcanic rocks of the Hekou Group in the Lala Copper Deposit area,southwestern Sichuan.The results show that all the analyses are concordant,and yield a weighted mean 207Pb/206Pb age of 1722±25 Ma(2σ,MSWD=0.5,n=11).We conclude that the Hekou Group is late Paleoproterozoic volcanic-sedimentary strata with a precise depositional age of 1722±25Ma. |
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| Keywords: | geochronology zircon LA-ICP-MS U-Pb dating Hekou Group Paleoproterozoic Yangtze Block |
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