TurkishJournalofEarthSciences (TurkishJ.EarthSci.),Vol.10, 2001,pp.35-49. Copyright©TÜB‹TAK Stratigraphy,GeochemistryandDepositionalEnvironment oftheCelestine-bearingGypsiferousFormationsofthe TertiaryUlafl-SivasBasin,East-CentralAnatolia(Turkey) ERDO⁄ANTEK‹N AnkaraUniversity,FacultyofScience,DepartmentofGeologicalEngineering, TR-06100Tando¤an,Ankara-TURKEY(e-mail:[email protected]) Abstract: Celestine-bearingevaporitemineralizationiswidespreadintheTertiaryevaporiticunitsoftheUlafl-Sivas Basin,east-centralAnatolia.Theoldestdepositionofgypsum,whichisoflaminatedcharacter,occurredina shallowinner-lagoonalenvironmentorindepressionsduringLateEoceneregression.Thickgypsumandoverlying bedscomposedofalternatingbedded,nodulargypsumandsandstonedevelopedincoastalsabkhasandabandoned channelswithinameander-rivercomplexduringOligocenetime.Thelastoccurrenceofevaporiticunits,namely massiveandbeddedgypsumalternatingwithsandstonesandfossiliferouslimestones,resultedfromlimitedmarine transgressionofanEarlyMioceneseaalongthesouthernmarginoftheSivasTertiaryBasin. ThecelestinedepositsarepredominantlyfoundwithinthegypsumbedsthroughouttheTertiarybasinandin subordinateamountsinthelimestonesoftheuppermostEoceneandasopen-spacefillingsingypsum,andas nodulesinthesomeoftheOligocenefluvialsandstone,claystonesandmassivegypsums.Large-scalelensesof celestineoccurwithinEarlyMiocenemassivegypsums.Thecelestinesampleswerestudiedbyscanningelectron microscopy(SEM),oremicroscopy,andelectron-microprobe(EMP),fluid-inclusion,selectedtrace-element(XRF) 18O/16O, 34S/32Sand 87Sr/86Srisotopegeochemistry.Fieldobservationsandanalyticalresultsindicatethatthe celestinedidnotdevelopviaprimarysedimentaryprocesses.Rather,high-temperatureconditionsprevailedduring late-diageneticorepigeneticcelestineformation. KeyWords: Celestine,Gypsum,Geochemistry,Uluk›flla-SivasBasin,East-CentralAnatolia TersiyerUlafl-SivasHavzas›ndaSölestiniçerenJipsliFormasyonlar›nStratigrafisi, Jeokimyas›veÇökelmeOrtamlar›,Do¤u-OrtaAnadolu(Türkiye) Özet: Do¤u-OrtaAnadolubölgesindeyeralanTersiyeryafll›Sivas-Ulaflevaporithavzas›ndayayg›nolaraksölestin içerenevaporitoluflumlar›bulunmaktad›r.Bunlarbafll›caüçzonaayr›labilir. BirincisiGeçEosenyafll›velaminal›birkaraktersergileyenjipslerdir.ButipjipslerEosensonundakiregresyona ba¤l›olarakoluflans›¤karakterliiçlagünlerdemineralleflmifllerdir.Bunlar›üzerleyenikincijipszonuiseOligosen yafll›d›rvebafll›caikitipfasiyessergilemektedir.Bunlarkal›nvemasifkarakterlijipsfasiyesiilekumtafl›aratabakal› nodülerjipsfasiyesidir.Oligosen’inbirincitipfasiyesis›¤sahilsabkhalar›nda,ikincitipfasiyesiisemenderesli akarsular›nterkedilmiflkanallar›içerisindeoluflmufllard›r.HavzadakiüçüncüvesonevaporitzonuiseErken Miyosenyafll›masifvetabakal›jipslerdir.Bunlar›ntabakal›olanlar›fosillikireçtafllar›vekumtafllar›ileyeryerara tabakal›d›rlar.Bölgedekibuengençevaporitmineralleflmesi,SivasTersiyerhavzas›n›nÜstMiyosenbafl›nda güneydengelens›n›rl›birdenizeltransgresyonunürünüdür. BuüçevaporitzonundakisölestinmineralleflmeleriiseSivas-UlaflTersiyerbasenindeoldukçayayg›nd›r. SölestinlerhavzadaenüstEosenyafll›kireçtafllar›vejipsleriçerisindeçatlak-karstikboflluklardadolgutürü tarz›nda,Oligosen’inflüvyalkumtafl›vekiltafllar›ilemasifjipsleriiçerisindeyumrularfleklindedir.ÜstMiyosen’in masifjipsleriiçerisindeisebüyükboyutlumerceklerbiçimindeyeral›rlar.Sölestinlerdeyap›lanarazi,elektron mikroskobu(SEM),cevhermikroskobisi,elektronmikroprob,s›v›kapan›m,izelement(XRF)ile 18O/16O,34S/32S ve87Sr/86Srizotopçal›flmalar›sedimanter-sinjenetikkökenlibirmineralleflmeyidesteklememektedir.Bunakarfl›l›k yükseks›cakl›kkoflullar›n›netkilioldu¤uepijenetikve/veyageçdiyajenetikoluflumflekliniiflaretlemektedir. AnahtarSözcükler:Sölestin,Jips,Jeokimya,Ulafl-SivasHavzas›,Do¤u-OrtaAnadolu 35 CELESTINE-BEARINGFORMATIONS,ULAfi-S‹VASBASIN,TURKEY Introduction Bischoff&Seyfried1978;Barbieri&Masi1984;Glynn& Manystudieshaveshownthatsomecelestineoccurrences Reardon1990;Dove&Czank1995). anddepositsofeconomicimportanceareassociatedwith Thegoalofthispaperistosetforthnew evaporiticsediments(e.g.,Müller1962;Evans& sedimentologicalandgeochemicaldataforthecelestine- Shearman1964;Usdowski1973;Rickman1977; bearingTertiaryevaporitesandtoprovideanew Olaussen1981;Kesler&Jones1981;Brodtkorb etal. approachtothismuch-debatedmineralization. 1982;Martinetal.1984;Kushnir1985;Carlson1987; Decima etal. 1987).Itwasreportedinmostofthose Regionalgeology worksthatcelestineoccurrencesarepresentinTertiary massive-gypsumunitsandweredepositedindifferent TheSivasBasinineast-centralTurkeyisoneofthethree ways. majorsedimentarybasinsofCentralAnatoliathat collectivelylieinacurvilinearbeltfollowingaperipheral TheTertiarySivasbasincontainsthemostimportant remnantbasinalongtheInner-Tauridesuturezone celestinedepositknowninTurkey.Thereareatleast25 (Görür etal. 1983;Erdo¤an etal. 1996).TheInner- celestineoccurrencesinthebasin;ofthese,onlyone Tauridesuturezonemarksthesiteofcollisionbetween (Körtuzlamine)isamajordeposit.Atotalof20million theTauridecarbonateplatformtothesouthandthe tonnesofcelestinehasbeenproducedfromtheKörtuzla CentralAnatolianCrystallineComplextothenorth,and minebytheopen-pitmethod.Celestine-bearinglayersin ophioliticfragmentsthatareremnantsoftheInner- theKörtuzlaminehavelengthsofupto850mand Taurideocean(Neotethyanbranch)occuralongthis widthsofupto100m,andareobservedaslensesin suturezone(Figure1a).TheSivasbasinevolvedfrom threedifferentzones.Theaveragegradeofthedepositis marinetolacustrineandfluvialenvironmentsbetween 55.2%SrO.Celestineoccurrencesinthebasinare thecollidingcrustalblocksastheinterveningInner- generallypresentwithingypsiferousunits(Tekin1995). TaurideoceanclosedduringTertiarytime.Thevolcanic Gypsumdepositsoftheregion(300kmlongand40-50 andsedimentaryrocksinthecenterofthebasinreston kmwide)extendfromfiark›fllainthewesttoRefahiyein anophioliticbasement.Theyconsist,frombottomtotop, theeast(Figure1a,b).IntheSivasbasin,thereareplaces ofPalaeocene-Eocenesiliciclastic,volcanogenicand wheretheevaporiticrockunitsexperiencedextensive carbonateflyschdepositswithshallowmarinelimestone tectonismanddiapirism.Themassivegypsumdeposits andmarl-gypsumintercalationsandolistolithsofvarious aremostlyboundedbystructuralfeatures,including lithologies;Oligocenefluvialsedimentsandgypsum; imbricatedthrusts.However,theageofthemassive massiveMiocenegypsum,fluvialsediments,basalticlavas, gypsumdepositsisstillcontroversial,butthesedeposits lacustrinelimestoneandcarbonaceousmudstone.The areconsideredtobeOligo-Mioceneinagebymany Eoceneandyoungersedimentaryrocksofthebasinonlap workers(Kurtman1961;Baysal&Ataman1980;Gökten thedeformedrocksoftheTauridecarbonateplatformto 1983;Gökçen&Kelling1985;Gökçe&Ceyhan1988). thesouthandtheAkda¤metamorphicmassiftothenorth Owingtoextensivetectonismanddiapirism,primary (Gökten1983;Gökçen&Kelling1985;Cater etal. structuralandtexturalfeaturesofmanyofthemassive 1991;Tekin1995). gypsumdepositshavebeendestroyed.Thissituation createsconsiderabledifficultywithregardtothe interpretationofdepositionalenvironments. Materialsandmethods ThecelestinedepositsintheSivasbasinhavebeen Inthisstudy,grabandlinesampleswerecollectedfrom investigatedbymanyresearcherssince1970,butthereis gypsumoccurrencesintheTertiaryseriesoftheUlafl- noconsensusontheoriginofthesedeposits.Todate, Sivasevaporiticbasin.Thesesampleswerethensubjected threedifferentgeneticinterpretationshavebeen topetrographicanalysisusingapolarizingmicroscope,as proposed:(a)sedimentary-syngenetic(Çubuk etal. inthestudyofMandado&Tena(1985).Thirtycelestine- 1992),(b)epigeneticmineralizationasproductofthe bearingsampleswerechosenformicrotexturalstudy hydrationofanhydrite(Ceyhan1996)and(c)epigenetic usingaJEOLJSM-840Ascanningelectronmicroscope mineralizationformedathightemperature(Gundlach (SEM),andforEDSstudiesusingaTracorTN-5502 1959;Strübell1969;Brower1973;Usdowski1973; instrument. 36 E.TEK‹N TOKAT Bulgaria BlackSea Georgia N ‹stanbul ZARA REFAH‹YE YILDIZEL‹ HAF‹K PONTIDES Greece Sivas Armenia AKDA⁄MADEN‹ S‹VAS TertiaryBasin Sivas KARAYÜN Ankara CELALL‹ N STUDY Iran AREA ULAfi ANATOLIDES Inner fiARKIfiLA Suture Tauride TAURIDES BORDERFOLDS K›z›l›rmakRiver AegeanSea Iraq GÜRÜN Syria 03060km a MediterraneanSea 0150km b KAYSER‹ Tha ET. N ET. * * Sr Sinekli Thp Akkaya Village Qal Ts Thp Kavlak Village T Thp Qal Sr 0 1.5 3 4.5 km ET. Sahantepe * Bahçecik ET.1 EXPLANATION Solgeçe Qal: Alluvium Ts * Unconformity Thp:Purtepe member, massive gypsum Tha: Aktas member, clastics-carbonates ET. Ayl Battalhöyüğü Unconformity * Ts: Selimiye formation, gypsiferous alluvial series Unconformity and local paraconformity Tb: Bozbel formation Tb (gypsiferous) ET.1 * Locations of measured stratigraphic c Sr : Celestinedeposits Figure1. (a) LocationoftheTertiarySivasbasininTurkey.(b) Locationmapofthestudyarea.(c) Simplifiedgeologicalmapofthestudyareashow- ingthelocationofthecelestinebeds. Twenty-sixgypsumsampleswereselectedand (Gladney etal. 1983)wereusedtodeterminethe analysedonaPhilipsPW-1400X-rayfluorescence analyticalprecisionoftheXRFstudies. spectrometerusingthestandardsofNorrish&Chappel Microprobestudieswereperformedonselectedthree (1977).Thesampleswerepowderedinanagatemortar samplesusingaJEOLJXA-8600electronmicroprobeand andthematerialpassedthrougha200meshsieve,that spectrophotometer.Forthisstudy,upto0.2mm-thick materialwasthenquartered,and15gofitwasusedto sliceswerepreparedandbothsidespolished,thencoated producepellets.USGSstandardsforF,Li,Ba,Pb,andCu 37 CELESTINE-BEARINGFORMATIONS,ULAfi-S‹VASBASIN,TURKEY withcarbon.ZAF,20.00kV,and40.0degreesettings thegypsumsamplesweredissolved,treatingthemfirst wereused. withNaOH,andlaterBaSO4wasobtainedbyreacting 18