Complex evolution of the sedimentation, metamorphism. deformation and hydrothermal processes and their constraints on the occurrence,enrichment and mineralization of Cointhe DahengluCu.Codeposit,JilinProvince.

The Dahenglu Cu-Co deposit in Baishan City, Jilin Province , is a large cobalt deposit in Northeast China. It is an ideal research area in investigating the multi-metallogenicprocesseswithinthePaleoproterozoicorogenicbelt,whosegenesisiscontrolledby multi.factorssuchassedimentation,metamorphismandhydrotherm.Atpresent,theoccurrence,enrichmentandmigrationofcobalt andthecomplexmineralizingprocessesofthisdepositwerepoorlystudied.Inthisstudy,representativedrillingsamplesfrom the DahengluCu.Codepositwereinvestigatedintermsofdetailedmineraltextureobservations,scanningelectronmicroscopeanalysis,X. rayelementmapping,andquantitativeanalysisofmineralcompositions.ItisrevealedthattheDahengluCu.Codepositunderwent multiplestagesofsedimentation,metamorphismandhydrothermalalterations.Thecobaltinthisdepositmainlyexistsintheformof independentminerals(i.e.,siegenite,cobaltiteandcobaltpentlandite),isomorphisminCo.enrichedpyriteandexsolutionofcobalt pentlanditeinpyrrhotite.Thepristinesedimentarystageismarkedbytheformationofveryfinemineralinclusionsofpyrite.pyrrhotite. chalcopyrite.Themetamorphicstageisrepresentedbytheorientedsiegenite.pyrrhotite.chalcopyriteaggregatesthataredistributedalong thephylliticfoliationdefinedbyhigh.greenschist.faciessericite.biotite.quartzassemblage.Theprecipitationofcoarse.veinedpyrrhotite andcobaltpentlanditeexsolutionwithinitdefinestheearly.stagehydrothermalmetasomatism.Thesubsequenthydrothermalstageis markedbytheformationofbandedeuhedralCo.enrichedpyriteandsiegenite,whichrepresentsthemainmetallogenicepoch.The precipitationofchalcopyriteoccursduringthelatehydrothermalmetasomatism,whichisaccompaniedbythegrowthoffine.grained cobaltite.Thealterationmainlyincludessilication,carbonatation,albitization,andchloritization,alongwithpotassicfeldspathization andsericitization.Thesilication,ankeritization,andalbitizationpredatethemetalsulfidehydrothermal.Thesealterationsmaynot correlatetotheComineralization,butwouldhaveprovidedtheprecipitatespacesforthemetalsulfides.Theprecipitationofcobaltiteis closelyrelatedtothechloritization,potassicfeldspathizationandsericitization.Inconclusion,multiplemetamorphicandhydrothermal eventssignificantlycontrolledthemigrationandenrichmentofthecobalt.TheprecipitationsofCo.enrichedsulfideswithdifferent occurrencesdevelopedthroughoutthedifferentevolutionstagesofthemetamorphism andhydrotherm.TheCo.enrichedpyriteand siegenitearetheprimaryCo.occurrencestatesintheDahengluCu.Codeposit.Insummary,theDahengluCu.Colargedepositinthe Liao.JiPaleoproterozoicorogenictectonicregimeunderwentcomplexevolutionprocessesofsedimentation.metamorphism.multiple hydrothermaloverprintingthatwererelatedtotheCoenrichmentandmineralization.TheDahengluCu.Codepositcanberegardedasan orogenicCu.Codeposit: thepristinesedimentation provided importantore.formingconditionsfortheComineralizaton; the Paleoproterozoicorogenicprocessandassociatedregionalmetamorphism anddeformationcontrolledtheoriginalComobilizationand migration;andthesubsequenthydrothermdominatedthemigrationand ultra-enrichment of the Co in the Dahenglu Cu-Co deposit