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| 山东微山稀土矿矿床成因:来自云母Rb-Sr年龄、激光Nd同位素及流体包裹体的证据 | |
| 引用本文： | 蓝廷广,范宏瑞,胡芳芳,杨奎锋,王永.山东微山稀土矿矿床成因:来自云母Rb-Sr年龄、激光Nd同位素及流体包裹体的证据[J].地球化学,2011(5):428-442. |
| 作者姓名： | 蓝廷广 范宏瑞 胡芳芳 杨奎锋 王永 |
| 基金项目： | 国家自然科学基金（40625010） |
| 摘 要： | 微山稀土矿位于华北克拉通东南缘的鲁西地块,为与碱性岩相关的伟晶岩型稀土矿床.根据单颗粒云母Rb-Sr定年,其形成于119.5 Ma,属于华北克拉通早白垩世大规模成矿事件的一部分.稀土矿物氟碳铈矿和独居石的激光Nd同位素研究表明,稀土矿的成矿物质与其围岩碱性岩一样,来源于富集地幔.对稀土矿脉中的石英、萤石和重晶石的流体包... |
| 关 键 词： | Rb-Sr等时线年龄 激光Nd同位素 流体包裹体 不混溶作用 微山稀土矿 华北克拉通 |
Genesis of the Weishan REE deposit, Shandong Province： Evidences from Rb-Sr isochron age, LA-MC-ICPMS Nd isotopic compositions and fluid inclusions |
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| LAN Ting-guang,FAN Hong-rui,HU Fang-fang,YANG Kui-feng and WANG Yong.Genesis of the Weishan REE deposit, Shandong Province： Evidences from Rb-Sr isochron age, LA-MC-ICPMS Nd isotopic compositions and fluid inclusions[J].Geochimica,2011(5):428-442. | |
| Authors: | LAN Ting-guang FAN Hong-rui HU Fang-fang YANG Kui-feng and WANG Yong |
| Abstract: | Weishan REE deposit, a pegmatite-type REE deposit related to alkaline rocks, is located in Luxi Block,southeastern North China Craton. Muscovite Rb-Sr isochron yields an age of 119.5 Ma, which belonged to the Early Cretaceous large-scale mineralization in the North China Craton. LA-ICPMS Nd isotopic compositions of bastnaesite and monazite indicate that the source of the REE deposit is the enriched lithospheric mantle. Four types of fluid inclusions have been identified in quartz, fluorite and barite, including （1） H2O inclusions （H）, （2） pure CO2 inclusions （C）, （3） H2O＋CO2 inclusions （HC） and （4） H2O＋CO2＋daughter mineral inclusions （HCD）.The H inclusions are secondary while others are primary. The daughter minerals in HCD inclusions include thenardite, barite, celestine, calcite, aphthitalite and glauberite. The homogenization and capture pressures of HC and HCD inclusions range from 205-433 ℃ and 120-200 MPa, respectively. Coupled with the existence of abundant daughter minerals and S stable isotopic compositions, it can be deduced that the initial ore-forming fluids were high-temperature, moderate-pressure and high-concentration orthomagmatic fluids, which were characterized by enrichment nt of HCO^-3 /CO^2-3,SO^2-4 and F– and multi-component （e.g., Na＋, K＋, Ca＋, Ba2＋, Sr2＋ and REE3＋）. The coexistence of C, HC and HCD inclusions and the wide range of liquid/vapor ratios between these inclusions suggest that fluid unmixing may have occurred during ore-forming process. REE were most probably transported as REEF]2＋ and precipitated through fluid unmixing. Fluids mixing, which contributed little to the REE precipitation, also happened in the late stage of the ore-forming process. |
| Keywords: | Rb-Sr isochron age LA-MC-ICPMS Nd isotopic composition fluid inclusion fluid unmixing Weishan REE deposit North China Craton |
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