新疆北部晚古生代岩浆Cu-Ni-Ti成矿作用动力学背景的流体组成制约

Many late Proterozoic (especially Carboniferous-Permian) mantle-derived magmatic Cu-Ni sulfide deposits and V-Ti magnetite deposits occurred in Central Asia Orogenic belt (CAOB) in northern Xinjiang, China are considered as formed in the dynamic setting of orogenic post-collision stretching (or tectonic slab window) superimposed a debating mantle plume. The samples of mafic- ultramafic rocks and ores from these magnetite deposits in Altay, Tianshan and Beishan metallogenic mafic ultramafic complex belts, and contemporary late Proterozoic basalts from Junggar, Turpan-Hami and Santanghu basins have been collected for the analysis of C-He-Ne-Ar isotopic composition and chemical composition of volatiles, because He-Ne-Ar isotopic compositions are unique to identify the matters of deep Earth and mantle plume. The data of C-He-Ne-Ar isotopic compositions and chemical composition of volatile, combine with the data of chronology, geochemical and Nd-Sr-Os-Hf isotopic compositions, are used to reveal the nature of primary magma, the composition and evolution of ore-forming magma sources of Cu-Ni sulfide deposits and V-Ti magnetite deposits, and to calculate the proportions of mantle, crust and atmosphere etc. different endmembers in the mineralization process of mantle-derived magma, and then to discuss the tectonic and deep geodynamic settings of ore-forming magmatism associated with magnetic deposits, finally to identify the mantle plume from these components. The scientific results will be significant to understand mantle-derived magmatic metallogenesis under the complex geodynamic settings of post-collision stretching (or tectonic window) superimposed the mantle plume, and provide the basis for revealing the regional lithosphere evolutions, continental crustal formation and growths.

新疆北部中亚造山带众多的晚古生代（尤其是石炭-二叠纪）幔源岩浆Cu-Ni硫化物矿床和钒钛磁铁矿矿床成矿作用的动力学背景被认为是碰撞后伸展（或板片窗）环境叠加争议的地幔柱作用。采用对地幔柱等深部物质鉴别具有独特作用的C-He-Ne-Ar同位素组成及流体组成等研究手段，系统研究阿尔泰、黄山-镜儿泉和北山岩浆矿床和成矿镁铁-超镁铁杂岩体，以及临近的准噶尔、吐-哈和三塘湖盆地同期的玄武岩，结合已有年代学、岩石地球化学和Nd-Sr-Os-Hf同位素组成数据，确定幔源岩浆矿床母岩浆性质、源区组成和演化特征，计算岩浆作用过程中地幔、地壳和大气等不同端元组分的贡献，探讨幔源岩浆矿床成矿构造环境及深部动力学，鉴别地幔柱作用的贡献，相关成果对认识造山带碰撞后伸展体制之下叠加地幔柱作用的独特环境下岩浆成矿作用具有重要的科学意义，为探索岩石圈演化和造山带大陆地壳垂向增生提供依据。

国家自然科学基金项目（批准号：41072056）选择新疆北部晚古生代岩浆Cu-Ni-Ti矿床，对比金川、峨眉山和塔里木大火成岩省等不同构造环境的岩浆矿床，开展岩相学、流体化学组成、C-He-Ar同位素和配套的年代学、岩石地球化学与Sr-Nd-Pb-Hf同位素分析，完善了岩石气体化学组成与同位素组成实验分析技术与示踪体系，确认不同构造环境基性岩浆作用的流体组成具有明显的差异，造山带构造环境腾冲新生代玄武质岩浆作用及夏日哈木岩浆镍铜硫化物矿床流体组成，峨眉山地幔柱环境朱布岩浆矿床流体组成中H2O、H2和H2S含量与Ni-Cu-PGE含量相关性表明流体对成矿金属的运移聚集、硫饱和等具有重要作用。揭示金川超大型铜镍铂族硫化物矿床和库鲁克塔格镁铁-超镁铁质岩体为新元古代Rodinia 超大陆裂解过程大陆裂谷与俯冲体系有关的玄武质岩浆作用在华北克拉通与塔里木克拉通的产物，准噶尔盆地二叠纪玄武岩流体组成显示幔源流体中混入大量的沉积热裂解来源气体，坡北岩体以H2O为主流体组份中存在深部地幔（地幔柱）来源组分。新疆北部岩浆Cu-Ni硫化物矿床和镁铁-超镁铁质杂岩体动力学背景被认为是碰撞后伸展（或板片窗）环境叠加地幔柱作用。