与地幔柱有关的成矿作用及其主控因素

地幔柱是地球动力系统中重要的组成部分,不仅形成规模巨大的大火成岩省,也形成了众多具有重要经济价值的矿床类型。由地幔柱形成不同的岩浆系列显示了特有的成矿专属性,如镁铁-超镁铁质层状岩体与钒钛磁铁矿矿床和铜镍硫化物矿床,科马提岩与铜镍硫化物矿床,斜长岩与钒钛磁铁矿矿床,过碱性花岗岩系列与铌-钽-锆-稀土矿床,金伯利岩与金刚石矿等。在分析与地幔柱相关矿床的基础上,我们认为地幔柱结构、岩浆源区特征、结晶分异过程、硫化物饱和、地壳混染和岩浆侵位过程等是地幔柱成矿的关键控制因素。本文还对矿床成因研究中的存在问题以及几种潜在的地球化学找矿/评价指标(如橄榄石的Ni含量、单斜辉石和磁铁矿中的Cr含量,层状岩体的PGE 含量和Re-Os同位素联合示踪等)进行了评述。

Mantle plume-related mineralization and their principal controlling factors

As one of the most important geodynamic systems, mantle plumes are not only responsible for the generation of large igneous provinces, but are also associated with many economically important mineral deposits. Plume-related magmatic sequences are found to host some specific mineralization, notably, mafic-ultramafic layered intrusions and deposits of Cr-Ti-Fe oxides and Ni-Cu-PGE sulfides, komatiite and related Fe-Ni-Cu deposits, anorthosite and Fe-Ti-V oxide deposits, peralkaline complex and Nb-Ta-Zr-REE deposits, and kimberlite and diamond. We are able to identify the following as key controlling factors in plume-related mineralization: structure of a plume, magma source, crystal fractionation, sulfide saturation, crustal contamination, and intrusion processes. Reviews are also given for outstanding issues on the studies of plume-related mineralization and for some potential diagnostic geochemical indicators of mineral prospecting/evaluation (e.g., Ni in olivine, Cr in clinopyroxene and magnetite, PGE concentration and Re-Os isotopes of layered intrusions).