西太平洋岛弧-弧后盆地热液活动及成矿作用

Hydrothermal Activities and Mineralization in the Arc and Back-Arc Basin Systems,Western Pacific

岛弧-弧后盆地是海底热液硫化物发育的重要环境。本文总结了近几十年对西太平洋地区岛弧-弧后盆地热液活动调查及研究的成果,阐述了岛弧-弧后盆地热液活动的分布规律、构造环境、热液喷口水深和流体温度变化关系、相分离过程以及热液硫化物的金属元素组成特征,分析了成矿元素富集规律和控矿因素。研究认为,随着岛弧-弧后盆地热液喷口所处水深的增加,其最高喷口流体温度也相应增加,这与相分离过程有关;岛弧-弧后盆地热液硫化物与洋中脊硫化物不同,以Fe-Zn-Pb型硫化物为主,显著富集Zn、Pb、Au、Ag等金属元素;热液成矿作用主要受到岛弧及弧后扩张处的岩浆作用、相分离、基岩、弧后扩张速率、沉积物盖层等5类因素的制约。

Island arc and back-arc basin systems are the important seafloor environments for the development of hydrothermal sulfide resources.In this study,we reviewed the results of international investigations and numerous studies on the hydrothermal activities and the accompanying sulfide mineralization processes in the arc and back-arc basin systems over the past few decades.We summarized geographical distributions,tectonic environments,water depths,vent fluid temperatures and phase separation process for the hydrothermal activities,and the sulfide types,element accumulationcharacteristics,ore body scales and the main ore-forming control factors for the hydrothermal sulfides in the systems.We suggested that,the variation trendy for the water depth of vents in the systems is the same as that for maximum vent fluid temperatures,and both of them are related to the phase separation process.Hydrothermal sulfides are mainly dominated by Fe-Zn-Pb type,and significantly enriched in the metal elements such as Zn,Pb,Au,Ag,etc.Hydrothermal mineralization is mainly controlled by the following five factors,island arc and back-arc magmatism,phase separation,basement rock,back-arc spreading rate and sediment.