斑岩铜矿若干问题的最新研究进展

斑岩铜矿是最重要的铜矿床类型,对其成矿作用的认识对找矿实践具有重要指导意义,为此,文章通过收集和整理有关文献总结了近年来斑岩铜矿研究在构造和岩浆对成矿作用的控制、成矿金属和成矿流体来源、矿石伴生金属组分含量的影响因素等方面所取得的成果。近几年的研究工作揭示:斑岩铜矿的大规模成矿作用与洋壳高浮力块体(包括无震海岭和洋底高原)的俯冲有关,高氧逸度的岩浆活动有利于斑岩铜矿的形成,与无矿斑岩体相比,含铜斑岩体一般具有低稀土元素含量以及亏损Ho和Er等特征;斑岩铜矿中铜和金多由俯冲洋壳所释放的流体对地幔中硫化物的氧化作用释放而来;在部分斑岩铜矿中,岩浆来源流体可构成绢英岩化期流体的主体;斑岩铜矿伴生金属组分的含量受许多因素控制,其中包括岩浆源区地幔演化、火成岩岩石类型、岩浆侵位深度和成矿温度等多个方面。部分研究成果应作为找矿标志在实践中运用。

The latest advances in researches on porphyry copper deposits

Porphyry copper deposits serve as major Cu,Mo and Re resources in the world,and a great abundance of research work has been carried out in this aspect in the past forty years.This paper reports the latest advances in the researches on such aspects as tectonic and magmatic conditions,origins of ore-forming fluids and metals,and factors controlling associated metallic components in porphyry copper deposits.Studies in recent years show that mineralization of porphyry copper deposits is associated with the subduction of relatively buoyant topographic anomalies of the oceanic crust and oxidization type magmatism.In comparison with barren porphyry intrusions,copper-bearing porphyry intrusions have lower total REE contents and display a right-inclined spoon-shaped pattern(i.e.,depletion of Er and Ho).Some researchers believe that copper and gold are derived from sulfides in the mantle,which are decomposed for interaction with Fe3 -rich fluids or melts derived from the subducted oceanic slab.Researches on copper deposits along the island arc of West Pacific Ocean indicate that magmatic water can exist as the main source of the phyllic stage fluids in some porphyry copper deposits.It is also recognized that gold and molybdenum contents of porphyry copper deposits are affected by many factors such as evolution of the mantle wedge caused by subduction-evolved magmatism,rock types and emplacement depths of associated porphyry intrusions,and mineralization temperatures.