DescriptiveandGeneticModelsforVolcanic-Hosted(“Volcanogenic”)MassiveSulfideDeposits(“VMS”)ofIron,Copper,Zinc,SilverandGold

(+variousotherminorelements)

火山巖塊狀硫化物（VMS）型Fe、Cu、Zn、Ag、Au及其它次要元素礦床的描述性及成因模型InstructorsZhaoshanChang,CODES,UniversityofTasmania,AustraliaDavidCooke,CODES,UniversityofTasmania,AustraliaRichGoldfarb,USGeologicalSurvey,Denver,USADaveLeach,USGeologicalSurvey,Denver,USAChusiLi,UniversityofIndiana,Cincinnati,USAStevenScott,UniversityofToronto,Toronto,CanadaNoelWhite,Consultant,Brisbane,AustraliaKaihuiYang,PresidentofAsiaNowResources,Toronto,CanadaOreDepositModels

TheirImportanceinResearchandExploration

礦床模型

礦床模型在勘探和研究中的重要作用NoelC.WhiteThayerLindsleyLecturer2008,SocietyofEconomicGeologistsGuestProfessor,ChinaUniversityofGeosciences,BeijingAdjunctProfessor,UniversityofQueensland,BrisbaneResearchAssociate,CentreofExcellenceinOreDeposits,UniversityofTasmania經(jīng)濟(jì)地質(zhì)協(xié)會(huì)榮譽(yù)學(xué)者,中國(guó)地質(zhì)大學(xué)(北京)客座教授,Queensland大學(xué)兼職教授,布理斯班塔斯馬尼亞大學(xué)礦床高級(jí)研究中心研究員WhatisanOreDepositModel?

什么是礦床模型?Itisasynthesisofavailableinformationonthedeposittype,includingthemostinformativeandreliablecharacteristicsrecognizedonavarietyofscales

礦床模型就是把某一礦床的各種有用的信息的綜合起來(lái)，包括不同尺度上識(shí)別出的最全面而可靠的特征Oredepositmodelschangeasourknowledgeadvances

礦床模型隨著我們所掌握知識(shí)的進(jìn)步而改變DESCRIPTIVEGENETICWhyareOreDepositModelsImportant?

為什么礦床模型如此重要?Oredepositsarecomplexandinvolvemanydifferentcharacteristics

礦床是復(fù)雜多變且包含多方面的特征Tectonicsetting構(gòu)造背景

Hostenvironment

地質(zhì)背景Hostrocks

圍巖Shapeandformoforebody礦體的形狀和形式Texturesofore礦石結(jié)構(gòu)Mineralogyofore礦石的礦物學(xué)特征Chemistryofore礦石的化學(xué)特征Ageofhostrocksandore圍巖和礦石的年齡Sourceandcompositionoffluids流體的來(lái)源及成分WhyareOreDepositModelsImportant?

為什么礦床模型如此重要?Chemicalandmineralogicalzoning化學(xué)和礦物學(xué)分帶Hydrothermalalterationmineralogyandzoning礦物學(xué)的熱液蝕變及分帶Structuralsetting構(gòu)造背景Structuralcontrols構(gòu)造控制條件Post-depositionalmodification(deformation,metamorphism,weathering)后期沉積變形作用(變形,變質(zhì),風(fēng)化)Geophysicalcharacteroforeandhostrocks(density,magnetism,chargeability,conductivity)礦體和圍巖的地球物理特點(diǎn)：密度,磁性,荷電率,導(dǎo)電率

Oredepositmodelsbringthekeycharacteristicstogetherinabriefandunderstandableway

礦床模型就是把礦床的主要特征用簡(jiǎn)單易懂的方法表示出來(lái)VerticalsectionthroughatypicalVMSdeposit(WhiteafterLydon,1984)

典型的VMS礦床的垂直剖面塊狀硫化物透鏡體塊狀的、碎石狀或角礫狀結(jié)構(gòu)（強(qiáng)烈的化學(xué)帶狀模型）地層網(wǎng)脈帶上盤突變接觸“氣成巖”或“凝灰?guī)r”層層狀或分層構(gòu)造（化學(xué)上非均質(zhì)）熱液蝕變通道下盤漸變接觸帶Py+Sp+Gn硫化物礦化Cpy+Py+Po硫化物礦化綠泥石化水熱蝕變絹云母化-綠泥石化水熱蝕變Transpositionofalterationpipebyshearing

由于剪切作用造成蝕變巖筒變位

(SangsterandScott,1976)VMS成因模型SameprinciplesapplytootherVMSsettings

與其它VMS背景原理相同現(xiàn)代海底水動(dòng)力特征Roleofsubvolcanicintrusions

e.g.,SturgeonLake,Canada(Archean)次火山侵入體的作用~85°~85°Temperature/FluidFlowModelAboveaSubvolcanicSillorCaldera

次火山巖席或破火山口之上的溫度/流體流動(dòng)模型

AnimationcourtesyofTuckerBarrieandLarryCathles

Runtime10,000years流動(dòng)時(shí)間為10000年1200°Cmaficintrusion(nochangeinventingpatternforanyT>600°C)1200°C基性巖侵入體(>600°C噴氣模型不變)VolcanicrocksofuniformpermeabilitybutincludestemperaturedependentthermalcrackingchannelroutinetoopenuppermeabilityFiniteelementmodellingatCornellUniversityusingAkcess?有限元素模型Source:Barrie,C.T.,Cathles,L.M.,Erendi,A.Carr,P.,Shosa,J.,Ioannou,S.,Spooner,E.T.C.,2001,HeatandFluidFlowModelingofGiantVMSSystems:CAMIROFinalReport,431p.[ProjectfundedbyCAMIRO,NSFandNSERC]

AgesofVMSDepositsVMS礦床的年齡

The“boringbillion”(~0.8-1.8Ga)wheretherearenoorogenicgold(R.Goldfarb)orsedex(D.Leach)depositsisnotseeninVMSdepositsbuttherearenoVMSdepositsfrom~1.9to2.7Ga.

“單調(diào)十億”（0.8-1.8億年）內(nèi)沒(méi)有造山型金礦，或者SEDEX礦床也沒(méi)有發(fā)現(xiàn)，但在1.9-2.7億年沒(méi)有發(fā)現(xiàn)VMS礦床。Noorogenicgoldorsedex~800–1800MaAllVMSdeposits

所有VMS礦床(GeologicalSurveyofCanadaworlddatabase)NoVMS~1.9-2.7Ga(Supercontinentbreakup?)VMSoresformedattimesofsubductionalongthemarginsofstablecontinents

穩(wěn)定大陸邊緣俯沖時(shí)期形成VMS礦床VMSgapDiagramcourtesyofRichardGoldfarb,USGS,DenverVMS礦床－時(shí)代VMS成因模型Experimentalplumeinatank(fromL.Gustafson,ANU)“BlackSmoker”ModelSouthCleftvideocourtesyofEdBaker,NOAA“黑煙筒”模型Falloutfromplumeproduces“exhalites”

熱柱形成的“噴氣巖”沉積AufromcoatingJapanese“tetsusekiei”exhaliteVMS成因模型BrinePoolModel鹵水處模型Densityofhydrothermalfluidsin(A)modernseafloorventsand(B)ancientVMSdeposits

不同條件下熱流體的密度：（A）現(xiàn)代海底噴氣孔；（B）古VMS礦床

Scott(1997)UndercertainconditionsofT,P,ρ,andflowrate,abouyantplumecanbecomenon-bouyant

在一定的T、P、ρ和流動(dòng)速率條件下，具有浮力的熱柱可能會(huì)變成不具備浮力。Transitionfrom“blacksmoker”(A)to“brinepool”(B)model?

從“黑煙筒”(A)向“鹵水池