| 江西龙南稀土花岗岩的锆石U-Pb年龄、内生矿化特征及成因讨论 |
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| 关键词:rare earth ore-bearing granite zircon U-Pb age endogenic mineralization petrogenesis Longnan region |
| 基金项目:中国地质调查局地质大调查项目“我国离子吸附型稀土战略调查及研究”(编号: 1212011220804);“南岭岩浆岩成矿专属性”(编号: 1212011120989) |
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| Zircon U-Pb Age, Endogenic Mineralization and Petrogenesis of Rare Earth Ore-bearing Granite in Longnan, Jiangxi Province |
| Granites related to ion adsorption type rare earth ore deposits are widely exposed in Longnan area, Jiangxi Province. However, there are different views concerning the emplacement age and petrogenesis of the granites due to the lack of accurate isotopic geochronologic data. In this paper, the authors conducted research on the zircon U-Pb chronology of the weathering crust or granite samples from Zudong, Niukeng and Bankeng granites by using Laser Ablation-Multicollector Inductively Coupled Plasma-Mass Spectrometry (La-MS-ICPMS). Three weighted average 206Pb/238U ages obtained are (168.2±1.2) Ma, (168.3±1.7) Ma and (209.75±0.86) Ma respectively. These data show that the emplacement ages of the Zudong and Niukeng granites are consistent with each other in consideration of the errors, suggesting the Yanshanian period. The ages are younger than the age of the Zhaibei-Guanxi granite (~195 Ma), and are much younger than the age of Bankeng granite which was emplaced during the Indosinian period. The Zudong and Niukeng granites have similar petrologic and mineralogical characteristics as well as heavy rare earth distribution patterns, implying that they might be products of the same stage of the comagmatic evolution. The Zhaibei-Guanxi and Bankeng granites also have similar petrologic and mineralogical characteristics and light rare earth distribution patterns, suggesting that they might be products of different stages of the comagmatic evolution. A comparison between the Zudong-Niukeng granite and the Zhaibei-Guanxi granite shows that they have different rare earth minerals, rare earth distribution patterns and trace elements characteristics (the Zr/Hf ratios of the weathering crust samples from the Zhaibei-Guanxi granite (20~60) are higher than those of the Zudong-Niukeng granite (<20), and they are positively correlated with the Nb/Ta ratios). It is believed that these granites originated from different magmatic source areas. |
| ZHAO Zhi,WANG Deng-hong,CHEN Zhen-yu,CHEN Zheng-hui,ZHENG Guo-dong,LIU Xin-xing.2014.Zircon U-Pb Age, Endogenic Mineralization and Petrogenesis of Rare Earth Ore-bearing Granite in Longnan, Jiangxi Province[J].Acta Geoscientica Sinica,35(6):719-725. |
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