巴布亚新几内亚铜金矿床成矿时代及成矿控制因素

Ages and controlling factors of Cu-Au mineralization in Papua New Guinea

巴布亚新几内亚是在澳大利亚板块与太平洋板块斜向和快速汇聚的边界带内演化的，是世界上构造运动最复杂的区带之一，其地球动力学演化涉及俯冲与火山岛弧（岩浆弧）形成、弧陆碰撞与造山、俯冲陆壳折返-岩浆侵入-成矿作用等地质作用。地质年代学研究指出，巴布亚新几内亚主岛（新几内亚岛）的地球动力学次序是：①引起抬升和折返的碰撞作用；②折返期间或稍后的侵入作用；③侵入岩体系晚期的成矿事件。在地球动力学次序中，巴布亚新几内亚铜金成矿时代主要集中在25～0Ma之间，其中几个世界级矿床更为年轻，成矿年龄只有6-0Ma。笔者按成矿时代将巴布亚新几内亚铜金成矿作用分为第一高潮（23～12Ma）、第二高潮（7-1Ma）和第三高潮（现在进行时）（0．5-0Ma）。巴布亚新几内亚铜金成矿受大地构造、侵入杂岩体、特定赋矿地层、转换构造、背斜、各种断裂、破火山或火山管道等控制。

The Papua New Guinea region evolved within the obliquely and rapidly converging Australian and Pacific plate boundary zone. It is arguably one of the most tectonically complex regions in the world, and its geodynamic evolution involved subduction and formation of volcanic （magmatic） arcs, arc-continent collision and coUisional orogenesis, exhumation of continental crust, magmatic intrusion and mineralization. The geochronology of New Guinea suggests the geodynamic sequence of（1） collision causing uphft and exhumation, then （2）intrusion during or shortly after exhumation, and finally （3）mineralizing event during the late stages of the intrusive system. In the geodynamic sequence, ages of Cu-Au mineralization are mainly concentrated in the range of 25-0Ma. Most of the world class deposits in PNG are much younger （6-0Ma）. On the basis of ages of mineralization, the authors divide Cu-Au mineralization into the three boom periods： the first boom of mineralization （23-12Ma）; the second boom of mineralization （7-1Ma）; the third boom of mineralization （0.5-0Ma） （still continuous at present）. The controlling factors of Cu-Au mineralization in Papua New Guin- ea include tectonics, intrusive complex, special host strata, transfer structure, folds, various faults, caldera or diatreme and so on. In summary, Papua New Guinea has a relatively young （Meso-Cenozoic） and complex history of tectonic and metallogenic evolution with plate convergence, colhsional orogenesis, and strong and frequent magmatic-hydrothermal activities,including Cu-Au mineralization.