TurkishJournalofEarthSciences (TurkishJ.EarthSci.),Vol.14, 2005,pp.255-280. Copyright©TÜB‹TAK GeneticRelationsBetweenSkarnMineralizationand PetrogenesisoftheEvcilerGranitoid,Kazda¤,Çanakkale, TurkeyandComparisonwithWorldSkarnGranitoids YEfi‹MYÜCEL-ÖZTÜRK1,CAH‹THELVACI1 &MUHARREMSATIR2 1DokuzEylülÜniversitesi,MühendislikFakültesi,JeolojiMühendisli¤iBölümü,TR–35100‹zmir,Turkey (E-mail:[email protected]) 2UniversitätTübingen,InstitutfürGeowissenschaften,LehrstuhlfürGeochemie,D–72074Tübingen,Germany Abstract: Mostskarndepositsaredirectlyrelatedtomagmaticactivity,andthereisasystematiccorrelation betweenthecompositionofcausativeplutonsandthemetalcontentsoftherelatedskarns.Thispaperdocuments thecompositionoffacieswithintheEvcilerplutonandcorrelationsbetweenintrusioncompositionandthemetal contentsofassociatedskarns.Therehavebeenpreviousstudiesofmines(e.g.,Cumines)intheEvcilerdistrict, however,therehavebeennodetailedgeologicalinvestigationsofsuchoredepositsorassociatedskarn mineralization.IntheEvcilerdistrictbothcalcicexoskarn(garnet-pyroxene)andendoskarn(pyroxene-epidote) occuralongthecontactsbetweengranitoidandmarble.Calc-silicatemineralcompositionsintheEvcilerskarnsare similartothoseinAu-CuandFe-Cuskarns. Basedonmineralogyandgeochemistry,threemainfacieshavebeenrecognizedintheEvcilerpluton:(1)the Çavufllumonzodiorite,(2)theKaraköygranodioriteand(3)theEvcilerquartzdiorite-granodiorite,themesocratic unitoftheEvcilerpluton.AttheEvcilerdistrict,monzograniticrocks,termedleucocraticEvciler,havealimited distributioncomparedtothemesocraticEvcilerrocks.Fieldevidencefortherelativetimingofintrusionsandtrace- elementgeochemistryoftheindividualfaciessuggestthattheEvcilerplutonformedinamagmaticarcorpost- collisionalsettingfromahybridsource,havingcrustalandmantlecomponentscontaminatedbyinteractionwith theuppercrust. Wholerock δ18OvaluesoftheEvcilergranitoiddecreasefrom8.5to2.5‰towardstheintrusivecontact, whichisclosesttothecalcicskarnmineralization(Au-Cu),andthequartzδ18OcompositionoftheEvcilergranitoid variesfrom7.2to10.9‰.ThesevaluesarenormalforI-type,primaryunalteredvaluesforthisintrusiverock, butaretoolargetobeaccountedforbysimplemagmaticdifferentiation.Therefore,theEvcilergranitoidmust havebeensubjectedtopost-emplacementopen-systemhydrothermalalterationwithintroductionofexternalfluids (probablymeteoricwater)whichchangedtheoriginalmagmatic δ18Ovalues. ThepresentstudyshowsthatthegeochemicalcharacteristicsoftheÇavufllumonzodiorite,Karaköy granodioriteandmesocraticEvcilerrocksaresimilartoaveragesforAu-CuandFe-skarngranitoids,whereasthe geochemicalcharacteristicsoftheleucocraticEvcilerrocksaresimilartoaveragesforSn-andMo-skarngranitoids. TheEvcilergranitoidisalsocharacterizedbyrelativelyunevolvedtomoderatelyevolvedandoxidizedsuites,asin mostAu-Cucoremetalassociationsglobally. KeyWords: gold,copper,skarn,mineralization,Evcilergranitoid,Kazda¤,NWTurkey SkarnMineralizasyonuveEvcilerGranitoyidinin (Kazda¤,Çanakkale,KBTürkiye)PetrojeneziAras›ndakiKökensel‹liflki veDünyadakiSkarnGranitoidleriileKarfl›laflt›r›lmas› Özet: Birçokskarnyata¤›do¤rudanmagmatikaktiviteileiliflkilidirveskarnyataklar›n›nmetaliçerikleriveskarn oluflumunanedenolanplutonlar›nbileflimleriaras›ndasistematikbiriliflkisözkonusudur.Buçal›flma,Evciler plutonuiçindekifasiyeslerinbileflimleriveintrüzyonbileflimivebiraradabulunduklar›skarnlar›nmetaliçerikleri aras›ndakikorelasyonuortayakoymaktad›r.Evcilerbölgesindeeskimadeniflletmeleri(örn.,Cumadeni) bulunmaktad›r,bununlabirlikteskarnmineralizasyonuveyabenzermadenyataklar›aç›s›ndanayr›nt›l›birjeolojik çal›flmayap›lmam›flt›r.Evcilerbölgesinde,kalsikeksoskarn(granat-piroksen)veendoskarn(piroksen-epidot) granitoidvemermeraras›ndakidokanakboyuncaortayaç›kmaktad›r.Evcilerskarnlar›ndakikalk-silikatmineral bileflimleri,Au-CuveFe-Cuskarnlar›ndanal›nanalterasyonminerallerininbileflimlerinebenzerdir. Evcilerplutonundamineralojikvejeokimyasalaç›danüçanafasiyesay›rtedilmektedir;bunlar,(1)Çavufllu monzodiyoriti,(2)Karaköygranodiyoritive(3)mezokratik-tipEvcilerolarakadland›r›lanEvcilerkuvarsdiyorit- graondiyoritidir.Ayn›zamanda,Evcilerbölgesindemonzogranitbileflimlikayaçlarmezokratik-tipEvciler’egöre dahas›n›rl›yay›l›msunmaktad›rvelökokratik-tipEvcilerolarakadland›r›lmaktad›r.Sokulumzaman›nailiflkinarazi verileriveherbirfasiyesinizelementjeokimyas›Evcilerplutonunun,üstkabuklaetkileflimilekirlenmifl,kabukve mantobileflenlerinesahipmelezbirkaynaktan,magmatik-yayveyaçarp›flmasonras›birortamdaolufltu¤unu önermektedir. 255 PETROGENESISOFTHEEVC‹LERGRANITOIDANDSKARN Evcilergranitoyidinintümkayaçδ18Ode¤erlerikalsikskarnmineralizasyonuna(Au-Cu)oldukçayak›nsokulum dokana¤›nado¤ru8.5‰’den2.5‰’eazalmaktad›rveEvcilergranitoidineaitquartz δ18Obileflimleri7.2’den 10.9‰’ede¤iflmektedir.Bude¤erlerI-tipialtereolmam›flintrüzifkayaçlariçinnormaldir,fakatbasitbirmagmatik farkl›laflmaiçinoldukçageniflbiraral›¤asahiptir.Bunedenle,Evcilergranitoyidi,bölgeyeyerleflimisonras›ndaaç›k- sistemhidrotermalalterasyonau¤ram›flvemuhtemelenmeteoriksugirifliileilkselmagmatik δ18Obileflimi de¤iflmifltir. Buçal›flma,EvcilergranodiyoritininjeokimyasalözelliklerininAu-Cu,Fe-skarngranitoyidlerininortalama de¤erleriilebenzerliksundu¤unugöstermektedir.Bunakarfl›n,EvcilerlökogranitiiseSn-veMo-skarn granitoyidlerinebenzerlikgöstermektedir.EvcilergranitoyididünyadakibirçokAu-Cuçekirdekmetaltopluluklar›na benzerflekildeilksel-ortaderecedeevrimgeçirmiflveoksideolmuflmagmalarlabenzerkaraktersunmaktad›r. AnahtarSözcükler:alt›n,bak›r,skarn,mineralizasyon,Evcilergranitoyidi,Kazda¤,KBTürkiye Introduction Thepresentstudyisthefirstreportofcorrelations TheEvcilergraniticplutonislocatedinKazda¤, betweenskarnsandtherelatedEvcilergranitoidinthe northwesternAnatolia,andisa170km 2 elliptical Kazda¤region,northwesternAnatolia,Turkey. metaluminouscalc-alkalinebody,withitslongaxis trendingWSW–ENE,ofLateOligocene–EarlyMiocene GeologicalSetting age(25±3Ma;Birkle1992),whichintrudestheKazda¤ Massif(Figure1). Studiesonthegeology,tectonics,petrologyand geochronologyoftheKazda¤Massifhavebeencarried Althoughtherearehistoricalworkings(mainlyCu outbyseveralworkers(e.g.,fiengör&Y›lmaz1981; mines)intheEvcilerdistrict,nomodernexploration Y›lmaz1989,1990,1995,1997;Okay etal. 1990, occurreduntil1996whenacompanyconducteddetailed 1996;Öngen1992;fiengör etal. 1993;Genç1998; stream-sedimentgeochemicalsurveystoidentify Okay&Sat›r2000;Duru etal. 2004).Thehigh-grade anomaliescausedbyhydrothermalalteration.Numerous metamorphicrocksoftheKazda¤mountainrange, copperandgoldanomalieswerefoundtobeassociated namedtheKazda¤group,cropoutasatectonicwindow withexoskarn.Theexplorationstudiesbythiscompany undertheKarakayacomplex(e.g.,Duru etal. 2004; focusedongeologyandore-reserveestimationof Göncüo¤luetal. 2004;Okay&Göncüo¤lu2004;Okay& mineralizationwithinindividualbodies,suchasthe Alt›ner2004;Pickett&Robertson2004andreferences pyrrhotite-richAuskarnzoneatthesouthendofthe therein)innorthwesternTurkey.TheKazda¤group Evcilerpluton.However,therelationshipbetweenskarns formsadoublyplunging,NE–SW-trendinganticlinorium. andassociatedplutons,andthepotentialfordifferent typesofmineralizationassociatedwiththeEvciler Duruetal. (2004)subdividedthemetamorphicrocks granitoid,havenotyetbeenstudied. intofourformations.ThelowermostunitistheF›nd›kl› formation,comprisingamphibole-gneiss,marbleand Broadcorrelationbetweenigneouscompositionsand minoramphibolite,andcropsoutmainlyinthesouthern themetalcontentsofassociatedskarnshasbeen partoftheKazda¤Massif.Theoverlyingunit,comprising describedbyseveralworkers(Zharikov1970;Shimazaki metaduniteandorthoamphibolite,istheTozluformation, 1975,1980;Kwak&White1982;Meinert1983,1995; whichinturnisoverlainbytheSar›k›zmarble.The Newberry&Swanson1986;Newberry1987;Keithetal. uppermostunit,whichcropsoutinthenorthernpartsof 1989;Newberry etal. 1990;Meinert etal. 1990; Kazda¤Massif,istheSutuvenformation;itcomprises Paktunc1990;Ishihara&Sasaki1991;Blevin&Chappell sillimanite-gneiss,migmatite,marble,amphiboliteand 1992;Naldrett1992;Rayetal. 1995;Srivastava&Sinha graniticgneiss. 1997;Nicolescu etal. 1999;Martin-Izard etal. 2000; Meza-Figueroa etal. 2003).Thesestudieshave TheSutuvenformationrestswithasharpcontacton documentedtherelationshipbetweenmetalcontentsin theSar›k›zmarbleandF›nd›kl›formation(Duru etal. mineraldepositsandmajor-andtrace-element 2004),andisintrudedbytheOligo–MioceneEvciler compositions,degreeofcrystallization,andtectonic granodiorite.TheSutuvenformationcomprisesmainly settingsoftherelatedplutons. grey,darkgreyandbrown,well-bandedquartzo- 256 N N N °ÝSTANBUL MARMARA SEA °ÇANAKKALE 315 Karaköy TURKEY Yeþilköy 0 100km AEGEAN SEA Kazdað Massif Mollahasanlar Y.YÜCELÖZTÜRK,C.HELVACI& M.SATIR Kestanbol Evciler 54-2 Eybekdað 52-2 41-2 modern graben fill granitic plutons with alluvium (Late Oligocene-Early Miocene) Aegean Sea upper sedimentary Ayvacýk assemblage metamorphic basement of Sakarya Continent (Late Miocene-Pliocene) Edremit Evciler Figure 2 Balabanlý volcanics ophiolite (Cretaceous) (Early-Middle Miocene) Burhaniye Ayvacýk volcanics normal fault (Early-Middle Miocene) 744 Küçükkuyu formation strike-slip fault Gulf of Edremit (Early Miocene) EH = Ezine Horst EG = Etili Graben Çavuþlu Bayramiç volcanics KZH = 0Kazdað Horst5 10 km a (Late Eocene-Oligocene) 750 0 3km cb Scale: alluvium granodiorite, Kazdað Massif quartz monzonite terrestrial quartz diorite, plastic-semiplastic sedimentary rocks granodiorite deformation zone upper volcanic monzodiorite, contact skarn association quartz monzodiorite aureole occurrence Early Miocene) rhyolite lower volcanic (Late Oligocene- fault sample association Evciler plutonic rocks 721 locality Figure1. (a) RegionalgeologicmapshowinglocationoftheEvcilerdistrict(simplifiedfromY›lmaz&Karac›k2001);