中文摘要：

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裹体研究显示, 流体包裹体主要分为以下4 类： （1）H2O 包裹体（H 类）,（2）纯CO2 包裹体（C 类）, （3）H2O＋CO2 包裹体（HC 类）和（4）H2O＋CO2＋子矿物包裹体（HCD 类）, 其中H 类包裹体为次生包裹体, 其余为原生包裹体, HCD 包裹体中的子矿物为无水芒硝、重晶石、天青石、方解石、钾芒硝和钙芒硝等。HC 和HCD 类包裹体的完全均一温度变化于205～433 ℃之间, 捕获压力在120~200 MPa 之间,结合子矿物大量发育, 成矿流体应为中压环境下的中高温、高浓度流体。这种流体富含 CO^2-3 、SO^2-4 、F-阴离子以及Na＋、K＋、Ca2＋、Sr2＋和Ba2＋等阳离子, 并且其中的S 同位素组成具有岩浆硫的特征, 因此,其可能来自碱性岩浆的分异, 通过岩浆-流体不混溶作用形成。C 类、HC 类和HCD 类包裹体的密切共生以及不同充填度包裹体的均一温度的相似表明流体可能发生不混溶作用。稀土元素主[REEF]2＋形式运移, 运移过程10：59 2011-9-30中的流体不混溶作用可能是稀土矿物沉淀的决定因素。成矿晚期可能发生流体混合作用, 但对稀土矿的沉淀贡献不大。

英文摘要：

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.