巴西卡拉加斯地区大规模铁-铜-金多金属矿床的成矿作用

Massive Fe-Cu-Au polymetallic deposits metallogenesis in Carajás mineral province of Brazil

巴西卡拉加斯(Carajás)地区是世界上矿床类型最为丰富、资源聚集程度最高的成矿带之一。早期该地区以巨型的浅层富集型铁-锰矿著称,近年发现了世界上最大的铁氧化物铜-金矿床(群)。并且,该区的小型脉状铜-金(钨-锡)矿床、浅成热液型金-钯-铂矿床、沉积型锰矿床和与超基性岩石关的铬-镍矿床也很有特色。综合研究表明,这一区域发生了4期成矿作用:新太古代早期铁-锰成矿作用、新太古代晚期铜-金-铀-稀土元素成矿作用、古元古代晚期铜-金(钨-锡)成矿作用和新元古代晚期金-铜成矿作用。而后新生代的表生作用,特别是红土化去硅富集作用对其进行了富集改造,形成了卡拉加斯地区大规模铁-铜-金矿集区。

The Carajds province of Brazil is one of the world famous metallogenic regions with various types of deposits and high concentration of minerals. It is well known for huge shallow enrichment type Fe-Mn deposits. In recent years the world＇ s largest iron oxide Cu-Au deposits and some distinctive small vein type Cu-Au （W-Sn） de-posits, epithermal Au-Pd-Pt deposits, sedimentary Mn deposits and Ni-Cr deposits related to ultrabasic rocks were discovered in this province. A comprehensive study shows that four periods of metallogenesis occurred in this region, namely early Neo-Archaeozoic Fe-Mn metallogenesis, late Neo-Archaeozoic Cu-Au-U-REE metallogenesis, late Paleoproterozoic Cu-Au（W-Sn） metallogenesis, and late Neoproterozoic Au-Cu metallogenesis. The Cenozoic supergenesis, especially laterized desilication enrichment, transformed Carajas into a large Cu-Au min- eral province.