简介:Onthebasisofmineralparagenesisandthechemistryandhomogenizationtemperaturesoffluidinclusions,thephysicochemicalparameterswerecalculatedfortheformationoftheDalingkouAg-Pb-ZudepositinZhejiang.Fromtheearlytothelatestageofmineralizationtheore-formingtemperatureveriationwasfoundtobe298.5℃→267.0℃→217.6℃→167.3℃,withacorrespondingpHchangeof3.0-5.8→6.1→6.7→5.0→7.3.Thepressurechangedfrom403.8to128.5atm,andlogfS2-9.9→-11.2→<-15;logfO2<-44→-45.6--42.6→>-44.2;andlogfCO2around-1.55.Inconjunctionwithgeologicalobservations.thedepositisconsideredtobeofmeso-epithermalorigin,i.e.,itwasformedaftercontinentalvolcanic-subvolcanicactivity.ThemajorfactorsaffectingoreprecipitationarethedecreasingtemperatureandtheincreasingpHofore-formingsolutions.
简介:MetallogenicDynamicsofZhashuiAg-PbPolymetallicOreDepositinShaanxi,ChinaWeiJunhao;LiJianwei;WangSiyuan(FacultyofEarthResources...
简介:Itisawellknownfactthatmagnaticcryoto-explosion,asaspeeialformofmagmatismunderthenear-surfacecondition,hasacloseconncctionwithcdogcnicmctaldcposits,particularlywiththoseofporphyrytyPe,suchaSporphyryCu-Mo,Pb-Zn,W-SnandUdcposits’However,onlyinrcccntyearsbavetheChineseoregeologistsandpetrologistsgivenin
简介:Ithaslongbeenacontroversyaboutthesourceofore-formingmaterialsofAu-Agpolymetallicdepositsbothinmetallogenictheoryandinore-searchingpractice.IntermsofalargewealthoftheisotopicstatisticsdatafromIndosinian-YanshanianendogenicoredepositsinnorthernHebei(generallyreferringtotheareasalongthenorthernpartofTaihangMountainsandnorthernHebei,thesamebelow),itisconsideredthattheore-formingmaterialscamefromthedeepinterioroftheEarth,whichhadmigratedthroughplumestotheEarthsurfacewhileex-periencedmulti-stageevolutionandthenemplacedprogressivelyinfavorablestructurallocitoformores.Theirisotopedatashowthat559sulfurisotopicdatafrom40oredepositsare,forthemostpart,withintherangeof-5‰-5‰,withahighdegreeofhomogenization,indicatingthatthesulfurisderivedmainlyfrommagma;200leadisotopedatafrom37oredepositsindi-catethattheore-formingmaterialsareprincipallyofmantlesourcethoughsomecrust-sourcema-terialwasinvolved;96oxygen,hydrogenandcarbonisotopedatafrom34oredepositsillustratethattheore-formingfluidsaredominatedbymagmaticwaterwhileothersourcesofwaterwouldbeinvolved.Itmaythereforebeseenthattheformationofendogenicdepositshasnothingtodowiththestrata.
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简介:WeperformedasystematictraceandrareearthelementanalysisforthebeddedFe-MncarbonaterocksrelatedtothestratiformAg-Pb-ZnmineralizationintheLengshuikengoredistrict,JiangxiProvince,SouthChina.ThreetypesofFe-Mncarbonatesaredistinguished,namely,themassive,breccia,andveintypes.Bothcarbonateandsilicatefractionsinthesamplesareanalyzedfortheirtraceandrareearthelementconcentrationsusingastepacid-leachingtechnique.OurresultsshowthatthecarbonatefractionsinthemassivetypesampleshavethelowestREEconcentrationsbutpronouncedpositiveEuandYanomalieswithEu/Eu*valuefrom1.3to6.2andY/Hovaluefrom40.1to59.5,andsimilarcharacteristicsarealsoshownforthesilicatefractionsinthemassivetypesamples(Eu/Eu*=1.0–6.7,Y/Ho=20.7–55.1).TheseREEcharacteristicsaresimilartothoseofSedextypemassivesulfidedepositsworldwide,andwesuggestthatthemassivetypeFe-Mncarbonaterockswerelikelyformedfromanexhalativevolcanic-hydrothermalfluidfeedingthedepressionbasinofavolcaniclake.Thehighconcentrationsofredox-sensitiveelementsandratiossuchasU/Th,V/CrandV/(V+Ni)indicateadysoxicenvironmentfortheFe-Mncarbonatedeposition.Incontrast,thebrecciatypeandveintypeFe-Mncarbonatesamplesshowdifferenttraceandrareearthelementfeaturesfromthoseofmassivetypesamples,andtheyaremoresimilartothevolcanicrocksandmagmatic-hydrothermalfluidsintheLengshuikengoredistrictandmayreflectstrongoverprintingfromvolcanicandsub-volcanicmagmatismrelatedtotheporphyrytypemineralizationinthedistrict.