非洲中南部赞比西造山带地质演化及矿产资源现状

Geological Evolution of the Zambezi Orogenic Belt,Central-Southern Africa and the Current Situation of Mineral Resources

赞比西造山带位于非洲中南缘,是新元古代-早古生代泛非造山运动的重要组成部分,形成于冈瓦纳古陆中心陆块缝合期间。赞比西带大地构造位置位于刚果克拉通和卡拉哈里克拉通之间,东连莫桑比克带,北接卢弗里安弧,西部和纳米比亚的达马拉构造带相呼应。带内主要地层单元为基底杂岩和一套沉积在硅铝质基底上的浅变质沉积序列。岩石学及构造学证据证明沉积作用发生在陆内裂谷盆地中,大量同位素年龄限制了盆地演化时代大致为880~820Ma;赞比西带在600~450Ma的泛非造山事件中再次活化,韧性剪切和大范围糜棱岩化导致了角闪岩相变质作用和同构造期花岗质岩体侵入事件同时发生。赞比西带目前已发现的矿产包括岩浆通道型镍硫化物矿床和浅成低温热液型硅锌矿等。笔者通过对赞比西带的地质演化和矿床成矿作用进行系统总结,并将赞比西带内的主要矿床和国内类似矿床进行对比分析,以期为赞比西带找矿实践提供依据或线索。

The Zambezi orogenic belt,located in the central-southern Africa,is a major part of Neoproterozoic Pan-African orogeny,which formed during the suturing of land blocks in the center of Gondwana.It lies between the Congo craton and Kalahari craton,linking with the Mozambique belt in east,Lufrian arc in the north,and Damara belt in west.The basement of this orogen is complex overlain by a suite of metamorphic sediment sequence.Petrological and tectonic evidence shows that sedimentation in this belt occurred in intracontinental rift basins,and a large number of isotopic ages constrain the evolutionary time roughly as 880~820Ma.The Zambesi belt was reactivated during the 600~450Ma Pan-African orogeny,during which the ductile shear and extensive mylonitization resulted in metamorphism and syntectonic granitic intrusion.The minerals discovered in this belt include Ni sulfide deposits and Willemite.This paper systematically summarizes the geological evolution and mineralization of the Zambesi belt and compares its major deposits with similar mines in China,expecting to provide a basis and clues for the prospecting practice in this region.