TurkishJournalofEarthSciences (TurkishJ.EarthSci.),Vol.13, 2004,pp.15-36. Copyright©TÜB‹TAK TheProblemoftheCore–CoverBoundaryoftheMenderes MassifandanEmplacementMechanismforRegionally ExtensiveGneissicGranites,WesternAnatolia(Turkey) BURHANERDO⁄AN&TAL‹PGÜNGÖR DokuzEylülUniversity,DepartmentofGeologicalEngineering,TR–35100Bornova,‹zmir-Turkey (e-mail:[email protected]) Abstract: Inpreviousstudies,thestratigraphyoftheMenderesMassifwasdividedintoaPrecambriancoreand Mesozoiccoverassociations,thecoreconsistingofgneissicgranitesandhigh-gradeschistsandthecoverofmica schistsandplatform-typemarbles.Ithasalsobeenproposedthatthetwoassociationsareseparatedbyan unconformityalthoughnowhereisthisrelationclearlyobserved. Inthisstudy,theBafaandKavakl›dereareasinthesouthernpartofthemassifhavebeenexamined.Inthe Bafaarea,Mesozoicmicaschistswithmarblelensesoccurinthelowermostpartsofthesequenceandareoverlain, alongagradationalboundary,byaMesozoiccarbonatesuccession.Gneissicgranitescutthedetritalpartsofthis Mesozoicsuccessionandtheboundaryisclearlyintrusive,characterisedbyenclavesofschistwithinthegranite bodyandseamsandveinsofgranitecuttingthesurroundingmicaschists.IntheKavakl›derearea,Mesozoic metaclasticsandplatformmarblesareunderlainbythePermo-CarboniferousGöktepeFormationwhichconsists ofblackmarble,chertandquartz-micaschistintercalations.Thegneissicgranitesinthisregionalsohaveintrusive contactrelationswithsurroundingrocksandcuttheGöktepeFormation. ThegraniteswereemplacedsyntectonicallyduringthemainMenderesmetamorphismwhichtookplaceinLate Cretaceous–EarlyCenozoictimeandincludedstronglyassimilatedmicaschistzonesandpatches.Thesegranites aregeochemicallyS-type,peraluminousandofsyn-collisionalcharacter. Thesubdivisionofthestratigraphyofthemassifintocoreandcoverassociationsbasedonthepositionofthe gneissicgranitesisincorrect.TheLycianNappeswerethrustnorthwardcoevallywiththemainMenderes metamorphism,andtheMenderesplatformwasrecumbentlyfolded.Alongthecoresofthesenorth-vergingfolds, graniticmeltswereemplacedsyntectonicallyandstronglyassimilated,andrejuvenatedthelowerpartsofthe platformsequence.Inversionofthemetamorphicgradeandverticalrepetitionofgneissesandmicaschistsinsome areasareconsequencesofrecumbentflowfolding. KeyWords: gneissicgranites,syntectonicgranites,MenderesMassif,westernAnatolia MenderesMasifindeÇekirdek–ÖrtüProblemiveBölgesel ÖlçekliGnaysikGranitlerinYerleflimMekanizmas› Özet: MenderesMasifi’ninstratigrafisiöncekiçal›flmalardaPrekambriençekirdekveMesozoyikörtütopluluklar› olmaküzereikianabölümeayr›lm›fl,çekirdekbölümününgnaysikgranitlerveyüksekdereceliflistler,örtü serilerininiseflislerveplatformtürümermerlerdenolufltu¤ubelirtilmifltir.Ayr›ca,çekirdekveörtütopluluklar›n›n birbirlerindenaç›saluyumsuzdokanakboyuncaayr›ld›¤›ilerisürülmesinera¤menbuiliflkihiçbiryerdeaç›kolarak gözlenememifltir. Buçal›flmadaMenderesMasifi’ningüneybölümündebulunanBafaveKavakl›derealanlar›incelenmifltir.Bafa alan›ndamermermercekleriiçerenMesozoyikyafll›mikaflistlerstratigrafikolarakaltdüzeyleriolufltururveüste do¤ruderecelibirkuflakboyuncaMesozoyikkarbonatistifinegeçmektedir.GnaysikgranitleralttakiMesozoyik k›r›nt›l›düzeylerikesmekte,dokanakiseintrüsifözelliktedir.Granitleriçindemikaflistanklavlar›bulunurken, flistlerdenoluflançevrekayalar›n›kesengranitbantvedamarlar›dokanakboyuncayeralmaktad›r.Kavakl›dere alan›ndaMesozoyikyafll›metak›r›nt›l›vemermeristifininalt›ndasiyahmermerler,çörtlervekuvarsmikaflistlerden oluflanPermo-Karboniferyafll›GöktepeFormasyonuyeral›r.Gnaysikgranitlerbualandadaçevrekayalara sokulmufl,do¤rudanGöktepeFormasyonu’nukesmektedir. Granitlersintektonikolarakyerleflmiflolupiçirisindeileriderecedeyutulmuflmikaflistzonveyamalar›bulunur. JeokimyasalözelliklerigüneyMenderesMasifi’ndekignaysikgranitlerinS-tipi,peraluminusveçarp›flmas›ras›nda yerleflmiflgranitleroldu¤unaiflaretetmektedir.Granitler,AnaMenderesMetamorfizmas›s›ras›ndaGeç Kretase–ErkenSenozoyikdönemindeçevrekayalar›n›oluflturanflistleriniçierisinesintektonikolarak 15 GRANITICGNEISSESOFTHEMENDERESMASSIF,WTURKEY yerleflmifllerdir.Bunedenlegnaysikgranitlerinkonumuesasal›narakyap›lançekirdekveörtüs›n›flamas›yanl›flt›r. Likyanaplar›,bus›radakuzeyedo¤ruitilmifl,bunaba¤l›olarakMenderesplatformubölgeselölçeklik›vr›mlarla deformasyongeçirmifltir.Granitikergiyiklerkuzeyedevrikk›vr›mlar›nçekirdekleriboyuncayerleflmiflveayn› zamandaplatformunaltbölümleriniergimeveyutmalaryoluylamobilizasyonau¤ratm›flt›r. AnahtarSözcükler:gnaysikgranitler,sintektonikgranitler,MenderesMasifi,Bat›Anadolu Introduction facingthrustfault(Ringetal. 1999,2001;Gessneretal. InthewesternpartofTurkey,theMenderesMassif– 2001a,2001b,2001c;Régnier etal. 2003).Onthe witharegionallymetamorphosedrocksuccessionof otherhand,morerecentlyitissuggestedthatthecontact gneissicgranites,micaschistsandmassivemarbles– wascontractionalwithtoptotheN–NNEsenseof formsthestructurallylowesttectonicunit,uponwhich shearing,theninvertedtoextensionalwithtoptothe tectonicslicesofmélangerocksofthe‹zmir-AnkaraZone S–SSWsenseofshearingduringEocene–Oligocenetimes inthenorthandtheLycianbeltinthesouthlieasnappes (Lipsetal. 2001;Whitney&Bozkurt2002). (Figure1). Boray etal. (1973),aftermappingalargeregion Inpreviousstudies,thestratigraphyoftheMenderes betweenMilasandTavasalongthesouthernedgeofthe Massifhasbeenconsideredtoconsistoftwomajorrock massif,pointedoutthatthecontactrelationshipbetween associations;thelowerpartwasnamedthe“ core”and thecoreandcoverseriescouldonlyberesolvedafter theupperpartthe“cover”ofthemassif(Schuiling1962; decipheringtheoriginofthecoregneisses. Dürr1975;Dora etal. 1992).Thecoreisconsidered Thestratigraphyoftheupperpartsofthemassif, PrecambrianinageandthecoverPalaeozoic,Mesozoic whichiscalledthecoversuccession,isrelativelybetter andTertiary.Thecorecomprisesvarioustypesof known(Figure2).Thecoverseriesconsists,initslower gneissesandhigh-gradeschists(Schuiling1962)andthe half,ofaverythicksuccessionofmicaschists,quartz- coverPalaeozoicandMesozoicschistsandmarbles.The micaschists,quartzites,blackchertsandlensesofdark intrusionageoftheorthogneissesofthecoresuccession greymarbles.CarboniferousandPermianageshavebeen hasbeendeterminedbyradiometricmethodstorange determinedfromthefossilcontentsofmarblesinthe from570to520Ma(Hetzel&Reischmann1996;Loos Kavakl›derearea(Önay1949;Konaketal. 1987;Güngör &Reischmann1999;Koralay etal. 2001)and566to &Erdo¤an2001).ThisPalaeozoicsuccessionis 541(Gessneretal. 2004). unconformablyoverlainbyaMesozoicsequence(Konak AlthoughthemetamorphicrocksoftheMenderes etal. 1987)whichstartsatitsbasewithpurpletoviolet MassifcropoutextensivelyinwesternTurkey,the sandstones,conglomeratesandphyllites(Figure2). boundaryoftheso-calledcoreandcoverassociationshas Therearethinlensesofdolomiticlimestonesandmafic notbeenobservedanywherenordescribedunequivocally. volcaniclenses(Güngör&Erdo¤an2001)intheupper IntheKavakl›derearea,theboundarywasreportedasan partsofthisdetritalTriassicsuccession,which unconformitycharacterisedbyconglomeratehorizons gradationallypassesupwardintoathickplatformmarble withclastsofleucocraticmagmaticrockswhichwere succession. interpretedtobederivedfromtheunderlying AroundMilas,thedetritalTriassicsectionincludes Precambriangranites(Konaketal. 1987).IntheSelimiye lensesofquartzconglomerates(Konak etal. 1987)and, regionalongthesouthernflankofthemassif,thesame aroundSelçuk,darkgraythinlybeddedcherts boundarywasdescribedasashearzone(Bozkurt1994, interbeddedwithphyllites,pelagicmarblesandmafic 1996;Bozkurt&Park1994,1997a,1997b,1999, volcanicintervalsarepresent(Güngör&Erdo¤an2001). 2001;Hetzel&Reischmann1996;Loos&Reischmann TheMesozoicmarblesinthesouthernpartofthe 1999;Bozkurt&Sat›r2000;Bozkurt&Oberhänsli massifconsistofgrayandlightgreydolomitesand 2001;Lips etal. 2001;Whitney&Bozkurt2002),and dolomiticmarblesinthelowerpartandwhitetodark asanincipientdetachmentzonealongwhichayoung graymassivemarblesintheupperpartoftheseries graniteintrudedbyBozkurt&Park(1994,1997a, (Borayetal. 1973;Dürr1975;Konaketal. 1987;Özer 1997b).Therealsoclaimsthatthiscontactisasouth- 16 B.ERDO⁄AN&T. GÜNGÖR BULGARIA N42º MACEDONIA TURKEY AEGEAN GREECE SEA ‹zmir N38º Athens Afyon E22º E26º Dibekda¤ N MAN‹SA KARABURUN GED‹ZGRABEN ‹ZM‹R 0 25 km Bozda¤ BELT ‹ZM‹R-ANKARA ZONE Seferihisar MENDERES MASSIF N38º Selçuk AYDIN Kufladas› MENDERESGRABEN Samos Söke BÜYÜK Figure2 Figure10 KAVAKLIDERE BAFA AREA AREA STUDY AREAS Göktepe AEGEANSEA Milas MU⁄LA Key LYCIANNAPPES normalFault thrustFault E47º E28º Figure1. MapshowingmaintectonicbeltsofwesternAnatoliaandthelocationofthestudyareas. 17 18 Qa E27o30’ N granite s s blocksofophiolites Eocene s s apophysis phylliteswithlensesof limestone 2km gray-pink, ?Palaeocene thinlybeddedmarbles rudist-bearingmarbles Figure3 metabauxites Cretaceous GRANITICGNEISSESOFTHEMENDERESMASSIF,WTURKEY recrystallisedlimestones Cuneolinasp. BEfiPARMAK Trocholinasp. Jurassic MOUNTAINS Thaumatoporellasp. Clypeinajurassica Reophaxsp. Serçin LAKEBAFA recrystallisedlimestones Qa dolomites Lamelliconusmultispirus anddolomitic Lamelliconussp. limestones Aulotortussp. maficmetavolcanicrocks vvvv alternatingwithrecrystallised limestonesandphyllites 30’ vvvv o violetbasalconglomerates EXPLANATION LAKEBAFA UpperLadinian -Carnian Qa alluvium Unconformity dolomitesand fossillifereous N37 blacklimestones Triassic massivemarbles Figure5 30’ thrustfault quartzitesand o blacklimestones gneissicgranites N37 micaschistsandphyllites blackcherts, phyllitesandlimestones ?Palaeocene withmetaconglomeratelenses MENDERESMASSIF Maastrichtian red,pelagicmarbles conglomeratelenses (channel-fill) Cretaceous massivemarbles Jurassic withemerydeposits Triassic micaschists Qa quartzitesandmicaschists