江南造山带钨锡稀有金属矿床成矿作用特征

Metallogenic Characteristics of Tungsten,Tin,and Rare Metal Deposits in the Jiangnan Orogenic Belt

江南造山带是世界上重要的钨锡稀有金属成矿带之一,发育矽卡岩型钨/锡矿、细脉浸染型钨矿、石英脉型黑钨矿/白钨矿、电气石-石英脉型锡矿、云英岩型钨/锡矿和花岗岩-伟晶岩型铌钽矿床,成矿时代包括新元古代、加里东期、印支期和燕山期。依据成矿元素组合,可将成矿花岗岩划分为W-Mo、W、Sn和Nb-Ta花岗岩,其演化程度和地球化学特征显示出明显差异,铌钽矿化发生在极端分异的钠长石花岗岩中。不同时代、不同类型的成矿花岗岩可能来自不同源区的部分熔融,江南造山带可能存在多个稀有金属富集的源区。成矿物质和成矿流体主要源自花岗质岩浆,岩浆分异演化促进了成矿元素在熔体中的富集。铌钽矿主要为岩浆成因,叠加热液矿化,钨锡矿主要通过流体充填和交代作用形成。

The Jiangnan Orogenic Belt is an important tungsten,tin,and rare metal metallogenic belt in the world.Skarn tungsten-tin deposits,veinlet-disseminated tungsten deposits,quartz-vein wolframite/scheelite deposits,tourmaline-quartz vein tin deposits,greisen tungsten-tin deposits,and granite-pegmatite niobium-tantalum deposits are developed in this belt.Four metallogenic epochs including Neoproterozoic,Caledonian,Indosinian,and Yanshanian have been identified.The ore-bearing granites can be divided into W-Mo,W,Sn,and Nb-Ta granites based on the metallogenic element assemblages,and their evolution degree and geochemical characteristics show significant differences.Nb-Ta mineralization occurs in the extremely differentiated albite granite.The ore-bearing granites with different ages and types are likely to have been derived from partial melting of sources.The ore-forming materials and fluids mainly originate from the granitic melts,where the magmatic fractionation facilitates the enrichment of ore elements in the melts.The Nb-Ta deposits are primarily of magmatic origin and subordinately overprinted by hydrothermal mineralization,while the W and Sn deposits are dominantly formed through fluid filling and metasomatism.