mvt和sedex铅锌矿床1

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1、IntroductiontoSediment-HostedPb-ZnDeposits:Part1:OverviewandComparisonofMVTandSEDEX沉积岩中赋存的铅锌矿第一部分：MVT和SEDEX型矿床的概述和对比DavidLeachUSGeologicalSurveyDenver,Coloradodleach@usgs.govdleach5100@mac.comhttp://idisk.mac.com/dleach5100-PublicPinePoint,NWTCanadaSediment-hostedPb-ZnOre沉积岩中赋存的铅锌矿Sedimentarybrin

2、esSeawater沉积型盐水海水SiliciclasticsCarbonateMixedClastics硅质碎屑岩碳酸盐混合碎屑岩SS-PbMVTSEDEXBHTVMSDistalskarnsCarbonatereplacementPolymetallicveins远矽卡岩碳酸盐岩交代体多金属脉Notincluded:FluoritedominatedPb-Zn不包括：萤石为主的Pb-Zn矿―TakeHomePoints‖要点•ISMYDEPOSITAMVTORSEDEX?怎么判断一个矿床是MVT型还是SEDEX型?•LAMINATEDORSYNGENETICTEXTURESCANBE

3、MISLEADING(MVTorSEDEX)纹层状或同沉积结构构造不可靠（可能是MVT型也可能是SEDEX型）•CARBONATE-HOSTED–MVTORSEDEXORSKARNORPOLYMETALICREPLACEMENT碳酸盐岩中赋存的矿床：可能是MVT型、SEDEX型、矽卡岩型或多金属交代型•TECTONICSETTTING–THEFIRSTANDMOSTIMPORTANTCONSIDERATION大地构造背景–最先要考虑也是最重要的因素•BOTHFORMBYSIMILARFLUIDSATSIMILARTEMPERATURES形成两者的流体和温度相似•THETECTONICSE

4、TTINGSETSTHEMAPART大地构造背景将二者区分开来•SEDEX:MAINLYPASSIVEMARGINSORPROTEROZICRIFT/SAGBASINSSEDEX型：主要形成于被动大陆边缘或元古宙裂谷/下陷盆地中•MVTCARBONATEPLATFORMSEQUENCESINPASSIVEMARGINSMVT型：被动大陆边缘的碳酸盐岩台地层序•SKARNOFTENCONFUSEDWITHMVT矽卡岩型常被误认为是MVT型SEDEXDefinitionSEDEX型的定义•CarneandCathro(1982):Laminated,exhalativesulfidesinf

5、ine-grainedclastic,carbonate,andmetasedimentaryrocks.CarneandCathro(1982)定义:细粒碎屑岩、碳酸盐岩和变质沉积岩中赋存的纹层状喷流成因硫化物•“Exhalative”componentinherentinthetermSEDEX术语本身就说明喷流成因•Directevidenceofanexhalitenotrequired–includessub-seafloorsystems.不需要有喷流物或海底之下成矿体系存在的证据.AssumedAgeofmineralization“same”or“closeto”ageo

6、fhostrocks假定的矿化年龄与赋矿围岩的年龄相同或非常相似Sedex=ClasticdominatedPb-ZnSEDEX=碎屑状为主的铅锌矿SEDEXOreTexturesSEDEX型矿石的结构构造•Typicallyfine-grained,laminatedandstrataform典型矿石为细粒,纹层状或层状•Maybesub-seafloorreplacive可能由海床下的交代作用形成•Varietyofhostrocks:shale,carbonate,coarseclastics各种各样的围岩:页岩,碳酸盐岩,粗粒碎屑岩•Typicallyfine-grainedbu

7、tcanbecoarse-grained典型矿石为细粒，但也可呈粗粒状Laminatedorbeddedsulfides纹层状或层状的硫化物Sphalerite-galenaLayers闪锌矿-方铅矿层TurbiditeLayers浊流岩层BlackshaleLayers黑色页岩层SEDEXClassificationsinLiterature文献中SEDEX型矿床的分类•Balmat-Edwards,UpperProterozoi