| 桂东大瑶山南缘社山花岗闪长岩的锆石U-Pb年龄及Hf同位素特征: 对区内加里东期成岩成矿作用的制约 |
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| 引用本文： | 李巍,毕诗健,杨振,梁培,唐克非.桂东大瑶山南缘社山花岗闪长岩的锆石U-Pb年龄及Hf同位素特征: 对区内加里东期成岩成矿作用的制约[J].地球科学,2015,40(1):17-33. |
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| 作者姓名： | 李巍 毕诗健 杨振 梁培 唐克非 |
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| 作者单位： | 1.广西壮族自治区地球物理勘察院, 广西柳州 545005 |
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| 基金项目： | 国家自然科学基金项目，中央高校基本科研业务费专项资金，广西壮族自治区地质矿产开发局科研项目 |
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| 摘 要： | 利用激光剥蚀(MC)-ICP-MS方法对桂东大瑶山南缘的社垌钨钼矿床中的花岗岩类进行研究, 精确限定社山黑云母花岗闪长岩(SD256)中锆石的206Pb/238U加权平均年龄为438.7±3.0 Ma(MSWD=0.22), 侵位于平头背石英砂岩的花岗闪长(斑)岩脉(SD190)形成于438.1±2.6 Ma(MSWD=0.28);花岗岩中新生岩浆锆石的Hf同位素特征较为一致, 176Hf/177Hf比值分布于0.282 406~0.282 518, 对应的εHf(438 Ma)值变化于-3.7~0, 两阶段Hf模式年龄(TDM2)集中在1 226~1 417 Ma之间.这表明大瑶山地区社山花岗闪长岩类的形成时间在438 Ma左右(加里东期), 成岩成矿作用可能与中元古代新生地壳物质(1.2~1.4 Ga)的部分熔融密切相关.结合区域内已有可靠年龄进行分析, 认为华南加里东期成岩成矿作用应该不是呈简单的北东向分布, 而是呈面状展布, 且该期构造-岩浆-成矿运动可能是引起华南地区在印支期、燕山早期发生大规模的岩浆作用和金属成矿作用的关键原因之一.
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| 关 键 词： | 社垌W-Mo矿床 地球化学 加里东期 成岩成矿作用 大瑶山 |
| 收稿时间： | 2014-06-19 |
Zircon U-Pb Age and Hf Isotope Characterization of Sheshan Granodiorite in Southern Edge of Dayaoshan,Guidong:Constraints on Caledonian Diagenesis and Mineralization |
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| Li Wei,Bi Shijian,Yang Zhen,Liang Pei,Tang Kefei.Zircon U-Pb Age and Hf Isotope Characterization of Sheshan Granodiorite in Southern Edge of Dayaoshan,Guidong:Constraints on Caledonian Diagenesis and Mineralization[J].Earth Science-Journal of China University of Geosciences,2015,40(1):17-33. |
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| Authors: | Li Wei Bi Shijian Yang Zhen Liang Pei Tang Kefei |
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| Affiliation: | Li Wei;Bi Shijian;Yang Zhen;Liang Pei;Tang Kefei;Geophysical Exploration Institute of Guangxi;State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences;Faculty of Earth Resources,China University of Geosciences;Guangzhou Institute of Geochemistry,Chinese Academy of Sciences; |
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| Abstract: | In this paper, we present laser ablation (MC)-ICP-MS U-Pb dating and Hf isotopic compositions of zircons from two representative granitoid samples collected from Shedong W-Mo deposit in the southern edge of the Dayaoshan. Highly precise U-Pb results indicate that zircons from Sheshan biotite granodiorite (SD256) and granodiorite-(porphyry) (SD190) which emplaced in the Pingtoubei quartz sandstone yields weighted mean 206Pb/238U age of 438.7±3.0 Ma (MSWD=0.22) and 438.1±2.6 Ma (MSWD=0.28), respectively. And the zircons crystallized in the Kwangsian granites yield 176Hf/177Hf ratios of 0.282 406 to 0.282 518, εHf(438 Ma) values ranging from -3.7 to 0 and Hf model ages (TDM2) of 1 226 to 1 417 Ma. Our U-Pb and Hf isotopic data can be interpreted as the crystallization time of granites, and indicate that it was formed in the ~438 Ma (Caledonian) and may have been formed by reworking of Mesoproterozoic juvenile crust (1.2-1.4 Ga) closely related to partial melting. Together with other published geochronological data, it is proposed that the late Early Paleozoic granites predominantly have a similar formation age and exhibit a planar-shaped distribution, rather than a north-east-striking-distribution pattern in the hinterland of the South China. Moreover, the Caledonian tectonic-magmatic-metallogenic movement may be the one of key reasons for the large-scale magmatism and metal mineralization in the following tectonic episodes, such as Indosinian and Yanshanian in the South China. |
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| Keywords: | Shedong W-Mo deposit geochemistry Caledonian diagenesis and mineralization Dayaoshan |
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