个旧锡矿东区黄铁矿成分标型特征研究

摘要

Pyrite is a common sulfide in Gejiu tin polymetallic deposit but research on it is rare.Geochemical characteristics of constant and trace elements of pyrite in different types of ore bodies in the east part of Gejiu are analyzed to get the composition typomorphic characteristics of pyrite.There are different ore body types here:interformation oxidized ore body with residual sulfides,karn ore body at contact,vein-like ore body,meta-colcanic rock ore body.Pyrites occur in the ore bodies are varied in texture,such as that in the oxidized ore body with residual texture,that in skarn type with crushing and skeleton.The data of pyrite of the study area are generally characterized by low iron and high sulfur enrichment of Pb,Zn,Cu,Cd,In,As,Sb,Bi,Sn,Ag,Au,W and depletion of Co,Ni,Cr,Te,Se and relatively high ratios of Co/Ni.The interformation oxidized ore body and meta-colcanic rock ore body occur in higher sulfur? fugacity environment.The pyrite of skarn ore body has higher content of high temperature elements.The total content of trace elements in vein-like ore body is higher.The higher of sulfur? fugacity and lower of temperature the easer As enters into the pyrite crystal lattice.The ore elements are abundant in the study area,As,Ag,Au probably derived from the strata,Pb from magma,Bi mostly from acidic magma.Temperature and mineral association have important effects on the enrichment of trace elements in pyrite.The chalcopyrite-pyrite association can indicate the temperature-pressure conditions.Pyrite in the study area is formed under medium-low temperature condition and indicating that from medium to low temperature skarn ore body-interformation oxidized ore body with residual sulfides-meta-basic volcanic ore body-vein-like ore body are formed.The mineralization temperature of the vein mine is the lowest,because the ore-forming fluid has distance and long time migration.The study of composition typomorphic characteristics of pyrite in east part of Gejiu can provide micro-information about forming environment,mineralization process,material source and composition and evolution characteristics of ore-forming fluids to support mineral exploration.%黄铁矿是个旧锡矿最常见的硫化物之一,但对其相关研究比较匮乏.本文通过对个旧锡矿东区不同类型矿体中黄铁矿的主微量元素特征研究获取黄铁矿成分的标型特征.个旧锡矿东区其矿体分为层间氧化残余硫化矿、接触带矽卡岩矿体、脉状矿、变基性火山岩矿体四类,不同类型黄铁矿产出特征各异,如层间氧化矿残余硫化矿中黄铁矿具有典型的残余结构,矽卡岩矿体中黄铁矿具有压碎结构、骸晶结构等.研究数据表明,黄铁矿总体表现亏铁、富硫,富集Pb、Zn、Cu、Cd、In、As、Sb、Bi、Sn、Ag、Au、W等元素,贫Co、Ni、Cr、Te、Se元素,Co/Ni较大.层间氧化矿残余硫化矿与变基性火山岩两类产于层间的矿体成矿环境硫逸度较高,矽卡岩矿体中黄铁矿高温元素含量较高,脉状矿中黄铁矿微量元素总量较高.硫逸度越大,温度越低,越有利于As进入黄铁矿晶格.成矿元素物源丰富,As、Ag、Au很可能来源于地层,Pb则来源于岩浆,Bi可能大部分来源于酸性岩浆.温度和共生矿物是影响黄铁矿中微量元素富集的重要因素,共生黄铁矿-黄铜矿可以指示形成时的温压条件.本区黄铁矿属中低温成矿,从高到低依次为矽卡岩矿—层间氧化矿残余硫化矿变基性火山岩矿—脉状矿.来自岩浆的成矿物源较丰富,以及产于岩体边缘蚀变岩型矿体的发现,可推测岩体内部矿产资源丰富.