Alteration

OutlineGeneralDescriptionoftheSariGunayAlterationSystemDescriptionsofDifferentAlterationTypesPresentAlterationHistoryoftheSariGunaySystem1、GeneralDescriptionoftheAlterationSystem石英-电气石角砾岩silicification硅化（电气石）Sericitic（phyllic）绢英岩化Kaolinitic（argillic）泥化Chloritic（propylitic）青磐岩化potassium钾化2、DescriptionsofDifferentAlterationTypesPresentTourmaline（电气石）AlterationSilicification（硅化）andQuartz-K-feldsparSericitic（绢云母化）(‘Phyllic’)AlterationIlliteAlterationAluniteAlterationKaolinitic（高岭土化）(‘Argillic’andSupergene)Chloritic(‘Propylitic’)AlterationOtherSupergeneAlterationMineralsPotassicAlteration（钾化）(withoverprintingFe-richCarbonatealteration)2、1Tourmaline（电气石）AlterationFeature：1、intheVBX，darkgreytoblackmatrix2、Outsidethe‘VBX’fineneedle-like（针状的）disseminationsandcavityfill。sericitealterationquartz-tourmalinebreccia(‘VBX’).2、1Tourmaline（电气石）AlterationWheretheVBXquartz-Tourmaline（电气石）brecciahasbeenusedasaconduit（通道）formineralisingfluidsthereisgold(e.g.muchofthecentralpartofSariGunay).thepresenceofTourmaline（电气石）hasaverygoodassociationwithgoldmineralisation•PIMAspectrafeature：InPIMAspectra（光谱）Tourmaline（电气石）hasadistinctiveironabsorptionfeatureat~2240nm.2、2Silicification（硅化）andQuartz-K-feldsparAlterationSilicification：veryFine-grained（细粒的）silicahaspervasi-vely（普遍地）alteredthefinegrainedgroundmass（基质）ofthedacite（英安岩）porphyriesandthefinecrystalmatrixoftheventtuffsandbreccias.Phenocrysts（斑晶）aretypicallynotsilicifedbutratherstronglyalteredtosericite（绢云母）(ex-feldsparPhenocrysts)ormuscovite(ex-biotitePhenocrysts).Silicification：InPIMAitwasfoundthatstrongareasofsilicificationwererepresentedbyverynoisyspectra,especiallyifthesilicaoccurredwithsignificantamountsofsulphide(whichisoftenthecase).•K-feldspar：fine-grainedpinkish（略带桃色的）K-feldspar•Opal：lightgrey、greasytextureandverylowdensityquartz2、3Sericitic（绢云母化）(‘Phyllic’)Alterationthreekindsofalterationofwhitemica:muscovitesericite(themostabundant)phengite(多硅白云母)Muscovite•muscovitereplacesbiotite，preservesthemicaplatesinthebiotitephenocrysts(假象pseudomorph)•Incore,muscoviteisasilvery-bronzecolourwithasatinsheen•ThePIMAcannotdifferentiatebetweensericiteandmuscovitebecausetheyhavethesamecomposition.Sericite•themostabundantalterationproduct•silkyluster•fine-grainedcrystalaggregates•InPIMAthewhitemicashaveanabsorptionfeatureintheAlOHwaveband.Thisfeatureisataround2202nmforsericitebutmovesasthecompositionofwhitemicachangesPhengite(多硅白云母)•themainmineralisingphaseofalteration•fine-grained,incloseproximitytotourmaline,strongsilicification•phengiticcomposition:highsulphidecontent•AlOHabsorptionbetween2210and2225nm•maybeassociatewithAu-mineralisingeventWherethemicaremainsofsericiticcompositionthereisnotlikelytobeanygold,except,perhapsindiscreteveins.2、4IlliteAlteration•difficulttodistinguishfrommontmorillonite、kaolinite、sericite•thewaterabsorptionfeaturesat1460nmand1910nm(illiteclayscontainsmorewaterthanthemicasillite2、5AluniteAlterationAluniteisthoughttobeafairlyminoralterationmineralintheSariGunaysystembutmayprovideimportantinformationonthegenesisofthemineralisingsystem.2、6Kaolinitic（高岭土化）(‘Argillic’andSupergene)AlterationnocorrelationbetweenkaoliniteandgoldKaolinite2、7Chloritic(‘Propylitic’)AlterationGoldmineralisationisnotassociatedwiththepropyliticalteration(bothinthelargehaloandininternalrafts)andisagoodindicatortobeingoutsideofthemaingold-bearingmineralisedzones.2、8OtherSupergeneAlterationMinerals•Halloysite（多水高岭土）•Montmorillonite（蒙脱石）•Jarosite（黄钾铁矾）Kaolinitealterationoffeldsparphenocrystswithanorangy-brownmontmorillonite2、9PotassicAlteration（钾化）(withoverprintingFe-richCarbonatealteration)•pink（粉红色）•anouterhalozoneofnumerousquartz-Fine-grained（细粒的）K-feldsparveinswhichcross-cutsercite-alteredorchlorite-alteredcountryrock.•Theseveinsoftencontainsmallamountsofpyrite,chalcopyriteandtennantite（砷黝铜矿）andcansometimesappearlikecopper-porphyrystyle‘A’or‘C’veins.3、AlterationHistoryoftheSariGunaySystemthedevelopmentoftheSariGunayalterationsystem：1、potassicalteration2、phyllicalteration3、quartz-Tourmaline‘VBX’breccias4、argillicalteration5、silicification（硅化），converthepreviouslyformedsericite（绢云母）intophengite（多硅白云母）[cyclicity]-旋回性Thankyou！