斑岩型铜（钼）矿床和斑岩型钼（铜）矿床是世界钼资源最主要的来源,提供的钼金属量相当。对比发现,两类矿床在流体来源-演化以及铜和钼的相关性上较为相似,而在铜/钼比值、品位、矿物共生组合、蚀变类型等方面存在差异,特别是斑岩铜（钼）矿初始出溶流体中的Cl-/F-值、硫的总量、SO2/H2S以及H＋/K＋比斑岩钼（铜）矿高。流体演化过程中有两方面因素可能影响最终沉淀的铜和钼比值（1）铜和钼在流体中的性质差异,如铜以氯或硫络合物形式运移,沉淀受温度影响比较显著,钼以羟基或氯络合物形式存在,沉淀受压力控制比较明显;（2）流体自身氧逸度、pH、硫逸度的变化以及演化路径的改变。然而,和初始流体性质的差异相比,流体演化过程对最终形成矿床类型的影响是有限的,决定矿床形成斑岩铜（钼）矿化还是钼（铜）矿化的因素可能在流体出溶之前的岩浆起源-演化阶段就存在。斑岩铜（钼）矿常分布在偏挤压的陆缘弧和大陆碰撞造山带环境,基底多为新生或加厚的陆壳,斑岩钼（铜）矿多出现在偏伸展的陆内裂谷、弧后及造山后伸展环境,基底可以为老陆壳或新生的陆壳;上述特征反映物源区或岩浆的起源和演化方式不同可能是制约形成斑岩铜（钼）矿还是钼（铜）矿的主要机制。%Porphyry Cu-Mo deposits and porphyry Mo-Cu deposits are the most important sources of world's Mo resources,each providing comparable Mo reserves.Although sharing the same characteristics in fluid source and evolution pattern and Cu-Mo correlation,those two types of deposits demonstrate many differences in Cu/Mo ratio,ore grade,mineral association,hydrothermal alteration type,and especially in primitive fluid composition,with fluids from porphyry Cu-Mo deposits containing more sulfur and showing higher ratios of Cl-/F-,SO2/H2S,as well as H+/ K+ than those from porphyry Mo-Cu deposits.Two factors may influence the final Cu/Mo ratio in a porphyry deposit during fluid evolution:(1) different behaviors of Cu and Mo in hydrothermal fluids(e.g.,Cu is usually transported as chlorine or sulfur complexes in fluids,the stabilities of which are dominantly controlled by temperature,while Mo mainly appears as hydroxyl or chlorine complexes,and their precipitation are principally influenced by pressure shift);(2) change of f(O2),f(S2),pH and evolution path of the primitive fluids.However,compared with the intrinsic differences of fluids from porphyry Cu-Mo and porphyry Mo-Cu deposits,fluids evolution process just have limited influence on the final types of deposits,indicating that the mechanisms which determine the final value of Cu/Mo must have already existed prior to the segregation of ore-forming fluids during magma generation and evolution.Porphyry Cu-Mo deposits are mainly distributed in compressional settings,including continental margin magmatic arc related to subduction of oceanic-slab and continental collisional orogenic belt,the basement of which is juvenile or thickened continental crust.In contrast,porphyry Mo-Cu deposits are mostly generated in extensional settings,such as continental rift,continental margin magmatic backarc and late extension stage of collisional orogenic belt,the basement of which may be ancient or juvenile continental crust.Those differences in distribution and tectonic setting may reflect that the variation in material sources and way of evolution of magmas are the principle mechanisms restricting the final products,whether porphyry Cu-Mo deposits or porphyry Mo-Cu deposits.
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