Geochemistry of Neogene–Quaternary alkaline volcanism in western Anatolia, Turkey, and ...

25 Pages·2010·0.97 MB·English

InternationalGeologyReview
Vol.52,Nos.4–6,April–June2010,631–655
Geochemistry of Neogene–Quaternary alkaline volcanism in western
Anatolia, Turkey, and implications for the Aegean mantle
YildirimDileka* and S¸afak Altunkaynakb
aDepartmentofGeology,MiamiUniversity,Oxford,OH45056,USA;bDepartmentofGeological
Engineering,IstanbulTechnicalUniversity,Maslak,Istanbul34469,Turkey
(Accepted17November2009)
The NS-trending alkaline volcanic province in western Turkey shows an age
progression from early Miocene in the north to Quaternary in the south, becoming
progressively more potassic–ultrapotassic southward. In three distinct volcanic
fields, Seyitgazi-Kırka (SKV), Afyon-Suhut-Sandıklı (ASSV), and Isparta-Go¨lcu¨k-
10 Bucak (IGBV), potassic (shoshonitic) and ultrapotassic rocks show close
0
2 relationships in space and time. Basaltic trachyandesites–trachyandesites and

ry coeval rhyolites-ignimbrites (21–17Ma) in the SKV represent the oldest phase of
a
nu alkaline volcanism in the area. The younger potassic rocks (14–8Ma) of the ASSV
a
J to the south are represented by trachyte and trachyandesite, whereas the youngest
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2 potassic rocks (4.7–4 and 200–24Ka) of the IGBV yet farther south are trachytic,
8
2 trachyandesitic, and rhyolitic in composition. Ultrapotassic rocks of all three fields
:
3
0 are transitional between lamproitic and Roman-type, although lamproitic

t: composition is dominant in the IGBV. Potassic and ultrapotassic rocks of the
A
] SKV and ASSV and the potassic rocks of the IGBV generally display similar trace
m
ri element characteristics. They are all enriched in large ion lithophile elements and
i
d light rare earth elements with respect to high field strength elements and show
l
i
Y negative Nb, Ta, and Ti anomalies. The first two groups are characterized

ek, by isotopic ratios of 87Sr/86Sr¼0.705219–0.707450, 1Nd¼6.3–0.5,
il 206Pb/204Pb¼18.90–19.07, 207Pb/204Pb¼15.65–15.85, and 208Pb/204Pb¼39.14–
D
[ 39.63, resembling the isotopic compositions of high-K, calc-alkaline lavas in
:
y western Anatolia and the shoshonitic and evolved lamproitic rocks in Serbia. In
B

d contrast, ultrapotassic rocks of the IGBV are characterized by higher contents of
e
oad CaO, MgO, Cr, and Ni, with a narrow range of SiO2 (47–52wt%). These rocks
nl are represented by nearly primitive lamproites and resemble the more primary
w
Do ultrapotassic rocks of Serbia. Ultrapotassic rocks of the IGBV are characterized by
more restricted 87Sr/86Sr¼0.7035–0.7036, positive 1 ¼1.7–2.5,
Nd
206Pb/204Pb¼18.7–19.1, 207Pb/204Pb¼15.69–15.75, and 208Pb/204Pb¼39.03–
39.29. These geochemical and isotopic features are consistent with subduction-
driven crustal-sediment recycling within the upper mantle. Observed variations in
the Sr–Nd–Pb isotopic signatures of the contemporaneous potassic and
ultrapotassic rocks suggest melting of a heterogeneous lithospheric mantle source
veined through metasomatism by previous subduction events. The within-plate
geochemical and isotopic components appear late in the evolution of the IGBV
ultrapotassic rocks. Isotopic differences from north to south are consistent with
decreasing amounts of subduction-derived crustal components in the mantle and an
increasing role of asthenospheric input through time. Combined with the depleted
*Correspondingauthor.Email:[email protected]
ISSN0020-6814print/ISSN1938-2839online
q2010Taylor&Francis
DOI:10.1080/00206810903495020
http://www.informaworld.com
632 Y. Dilekand S¸. Altunkaynak
mantle model (T ) age data, these observations suggest the occurrence of a
DM
vertically zoned mantle beneath southwest Anatolia and the Aegean region.
Keywords: alkaline volcanism; potassic–ultrapotassic rocks; lamproites and
shoshonites; subduction-metasomatized mantle; asthenospheric melt; Neogene–
Quaternarymagmatism;westernTurkey
Introduction
ThegeochemicalandtemporalevolutionoflateCenozoicmagmatisminwesternAnatolia
hasbeenstronglycontrolledbyaccretionarytectonicsandcollisionalevents,extensional
tectonics, subduction-zone processes, collision-induced mantle dynamics (i.e. slab
breakoffanddelamination),andasthenosphericupwelling(Figure1;Fytikasetal.1984;
Jolivet and Faccenna 2000; Dilek and Altunkaynak 2009; Dilek and Sandvol 2009; and
references therein). The initial Cenozoic magmatism that produced widespread calc-
alkaline granitoids and their extrusive counterparts (Figure 2) was post-collisional in
0 natureandfollowedthecollisionoftheSakaryaandTauridecontinentalblocks(Figure1)
1
20 inthelatePalaeocene.MagmasoftheseEocenetoOligo-Miocenevolcano-plutonicunits

y
r were derived from moderately to strongly evolved melts with subduction-zone
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an geochemicalsignatures.Thesubductioncomponenttothemantlesourcewasintroduced
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4 byearlier(Cretaceous–earlyCenozoic)subduction-accretioneventsintheTethyanrealm
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8 (hence the historical contingency) that contributed to the metasomatization and
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03 heterogeneityofthelithosphericmantlebeneathwesternAnatoliaandtheAegeanregion

t: (Altunkaynak andDilek 2006; Dilekand Altunkaynak 2009).
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Figure1. TectonicmapoftheAegeanandeasternMediterraneanregion,showingthemainplate
boundaries, major suture zones, and fault systems. Thick, white arrows depict the direction and
magnitude(mm/year)ofplateconvergence,greyarrowsmarkthedirectionofextension(Miocene–
Recent).OrangeandpurplecoloursdelineateEurasianandAfricanplateaffinities,respectively.Key
tolettering:DSF,DeadSeafault;EF,Ecemisfault;IAESZ,Izmir–Ankara–Erzincansuture;ITS,
Inner-Tauride suture; KOTJ, Karliova triple junction; MS, Marmara Sea; MTR, Maras triple
junction; NAFZ, North Anatolian fault zone; OF, Ovacik fault; TF, Tutak fault (modified from
Dilek2006).
International Geology Review 633
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Figure2. SimplifiedgeologicalmapofwesternAnatoliaandtheeasternAegeanregion,showing
thedistributionofmajorCenozoicigneousprovincesandthesalientfaultsystems(modifiedfrom
DilekandAltunkaynak2009).MenderesandKazdag(KDM)massifsrepresentmetamorphiccore
complexes with exhumed lower continental crust. Izmir–Ankara suture zone (IASZ) marks the
collision front between the Sakarya and Tauride continental blocks. The post-collisional Eocene
granitoids(showninred)straddlethissuturezone.Cenozoicvolcanicrocksandterrestrialdeposits
634 Y. Dilekand S¸. Altunkaynak
ExtensionaltectonicswaswidelyoperatinginwesternAnatoliabythelateMioceneand
was accompanied by alkaline magmatism (Ercan et al. 1985; Gu¨lec¸ 1991; Dilek and
Altunkaynak2007,2009;andreferencestherein).Mainlyshoshoniticvolcanismintheearly
stagesofthisphaseprogressivelygavewayintomorepotassic–ultrapotassiccompositions
inthelaterstagesandpropagatedsouthwardovertime(AthroughDinFigure2;Alıcıetal.
1998,2002;Savasc¸inandOyman1998;Aldanmazetal.2000;Innocentietal.2005;C¸oban
and Flower 2006). Late Miocene–Pliocene to Quaternary volcanism produced basalts,
basanites, phonotephrites, alkali basalts, and lamproites (Richardson-Bunbury 1996;
Seyitogluetal.1997;Savasc¸inandOyman1998;Aldanmazetal.2000;Francalancietal.
2000;Alicietal.2002;Innocentietal.2005;Elitoketal.2009)thatarecommonlyspatially
associated with major extensional and oblique-slip fault systems (Figure 2). Thus, the
productsofmostrecentvolcanisminwesternAnatoliaarecompositionallymoreakinto
intraplate oceanic island basalts and indicate the involvement of a convecting
asthenosphericmantleaccompanyingmeltevolutionbeneaththeregion.
This significant shift in western Anatolia from early Cenozoic post-collisional calc-
0 alkalinemagmatismtolateCenozoicextensionalultrapotassic,anorogenicmagmatismisa
1
20 resultofacomplexinterplaybetweenplateboundaryprocessesandmantledynamicsand

ry providesauniqueopportunitytofingerprintthegeochemicalevolutionofthemantlesource
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n beneath a young orogenic belt. Specifically, the close spatial and temporal relationships
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4 betweenearlyCenozoicorogenicmagmaproductsandlateCenozoicanorogenicmagma
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8 typeswithinthesamegeodynamicsettingrequireacarefulevaluationoftheirmantlemelt
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3 sourceandmeltevolutionthroughtime.Inthispaper,wefocusonthegeochemistryand
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t: petrogenesisoftheNeogene–Quaternaryalkalivolcanism,whichproducedaNS-trending
A
] linearvolcanicprovinceintheIspartaAngleregionofwesternAnatolia,Turkey(Figures1
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r and 2). We present new geochemical and isotope data from three volcanic fields in this
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il provinceanddiscussthespatialandtemporalevolutionofthevolcanismthatproducedthe
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, Neogene–Quaternarypotassic–ultrapotassicextrusiverocksinthisregion.Ourdataand
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l interpretationssuggestaverticallyzoned,heterogeneousmantlesourcebeneaththeregion
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[ thatbecameyoungertowardsthesouth,asdiditsextrusivemeltproducts.
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ed Geological setting of alkaline volcanism inthe Isparta Angle region
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l TheIspartaAngleisamajorre-entrantintheTaurideribboncontinentinwesternAnatolia
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Do (Kisseletal.1993)andoccursattheintersectionbetweentheHellenic(west)andCyprus
(east)arcsintheeasternMediterranean(Figures1and2).TheapexoftheIspartaAngleis
situated at a pivot zone between the Bey Daglari (west) and Anama-Akseki (east)
carbonate platforms. Previous studies have suggested that the rotational movements of
thesetwocrustalblocksmighthavecreatedthiscuspwithintheTauridecontinent(Dilek
andRowland1993;Kissel et al.1993). Palaeomagnetic investigations suggestthatthere
has been very little rotation of the Isparta Angle in the last 10million years (Tatar et al.
2002). Therefore, any rigid rotational movements of the crustal blocks must have taken
R
covermuchofwesternAnatolia.Blueboxesdepictthearealextentofvolcanicfieldsinvestigatedin
this study. Letters A through D mark the type localities of the Neogene–Quaternary alkaline
volcanicfieldsintheIspartaAngleregion,whicharealsodisplayedinFigure4.Keytolettering:AF,
Acigo¨l fault; BFZ, Burdur fault zone; DF, Datc¸a fault; IASZ, Izmir–Ankara suture zone; IPSZ,
Intra-Pontide suture zone; KDM, Kazdag metamorphic massif; KF, Kale fault; NAFZ, North
Anatolianfaultzone.Keytoletteringforthegranitoidplutons:CGD,C¸ataldag;EGP,Egrigo¨z;EP,
Eybek; GBG, Go¨ynu¨kbelen; GYG, Gu¨rgenyayla; IGD, Ilica; KG, Kozak; OGD, Orhaneli; TGD,
Topuk.
International Geology Review 635
place prior to the middle Miocene. The Bey Daglari carbonate platform on the western
limboftheIspartaAngleisdissectedbyabroad(,40kmwide),left-lateralfaultsystem,
whichcomprisestheBurdur(BFZ),Acigo¨l,andKalefaults(Figure2).Thecentreofthe
Isparta Angle is occupied by the Kovada Graben, which represents a NS-trending,
transtensional shear zone. The left-lateral fault system in the west extends into the Pliny
Trench at sea, which constitutes the eastern end of the Hellenic arc (Figure 1).
SeismogenicdeformationalongtheHellenicarcindicatesatransitionfromcompressional
tonormalfaultingneartheIspartaAngle.Theglobalpositioningsystemvelocityvectors
ofMcCluskyetal.(2000)suggestthatthelithospherewithintheIspartaAngleismoving
independentlyoftherestoftheAnatolianplateandthatitmaybeattachedtotheAfrican
plate or toa piece ofit (Barka and Reilinger 1997; McClusky et al.2000).
ItismostlikelythattheIspartaAngleisasurfaceexpressionofthesharpcuspbetween
theHellenicandCyprustrenches(Figure1).Thesignificantdifferencesintheconvergence
velocities of the African lithosphere at these trenches, ,40mm/year at the Hellenic and
,10mm/year at the Cyprus trench, may have produced a lithospheric tear in the
0 downgoing African plate that allowed the asthenospheric mantle to rise beneath SW
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20 Anatolia (Doglioni et al. 2002; Agostini et al. 2007; Dilek and Altunkaynak 2009).

ry Asthenospheric low velocities detected through Pn tomographic imaging in this region
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n (Al-Lazkietal.2004)supporttheexistenceofshallowasthenospherebeneaththeIsparta
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4 Angle at present. Dilek and Altunkaynak (2009) have proposed that this scenario is
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8 reminiscentoflithospherictearingatsubduction-transformedgepropagator(STEP)faults
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3 described by Govers and Wortel (2005) from the Ionian and Calabrian arcs, the New
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t: Hebridestrench,thesouthernedgeoftheLesserAntillestrench,andthenorthernendofthe
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] SouthSandwichtrench.Inalltheseexamplesofobliqueconvergentmarginsettings,STEP
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r faults propagate in a direction opposite to the subduction direction, and asthenospheric
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il upwelling occurs behind and beneath their propagating tips. This upwelling induces
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, decompressionalmeltingofshallowasthenosphere,leadingtolinearlydistributedalkaline
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l magmatismyounginginthedirectionoftearpropagation(DilekandAltunkaynak2009).
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[ Majoreruptioncentresofpotassic–ultrapotassiclavasintheIspartaAngleregionthat
:
By wehaveinvestigatedinthisstudyincludetheSeyitgazi-Kirka,Afyon-Suhut-Sandikli,and

d
e Isparta-Go¨lcu¨k-Bucakvolcanicfields(Figure2).Thesevolcanicfieldsrangeinagefrom
d
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lo 21–17MaintheSeyitgazi-Kirkaand14–8.7MaintheAfyon-Suhut-Sandiklito4.6–4.00
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ow and 200–24Ka in the Isparta-Go¨lcu¨k-Bucak fields (Yagmurlu et al. 1997; Alici et al.
D
1998, 2002; Savasc¸in and Oyman 1998; Aldanmaz et al. 2000; Francalanci et al. 2000;
C¸obanandFlower2006;Kumraletal.2006;Platevoetetal.2008).Thisdistributionofthe
potassic and ultrapotassic volcanic fields in the Isparta Angle region is consistent with a
progressivemigrationoftheirmeltsourcetowardsthesouthandsupportsaSTEPmodel
for their origin(Dilek andAltunkaynak 2009).
The Seyitgazi-Kirka volcanic field occurs between the Eskisehir (north) and Afyon-
Ku¨tahya (south) fault zones (Figure 2). The lower Miocene basaltic-trachyandesitic,
trachyandesitic, and rhyolitic lavas, ignimbrites, and tuff deposits are interlayered with
lacustrine carbonate and clastic rocks and are overlain by middle to upper Miocene
basalticlavas,latites,trachytes,andphonolitictephritesandlimestone-chertintercalations
(Figures3(a),4(a)and(b);Keller1983;Yalc¸in1989).Basalticlavascanbelocallyseveral
hundred metres thick (i.e. Tu¨rkmendagi basalt). Ryholitic plugs occur along NW–SE-
trending oblique normal faults. Farther south in the Afyon-Suhut-Sandikli volcanic field
(Figure 3(a) and (b)), the middle Miocene (,14Ma) latitic and trachytic lavas are
interlayered with agglomerates, tuffs, and volcanosedimentary rocks (Keller and Villari
1972;C¸evikbasetal.1988;Yagmurluetal.1997).TheupperMiocenetrachyte,leucitic
636 Y. Dilekand S¸. Altunkaynak
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Figure 3. Google Earthe images of the Afyon-Kirka (a), Isparta-Go¨lcu¨k (b), and Kula (c)
volcanic fields, showing the distribution of distinct volcanic landforms and products in their
geological settings. In all three fields, volcanic units are spatially associated with crustal-scale
fault systems.
International Geology Review 637
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Figure4. (a)UpperMiocene–PliocenebasalticlavaflowsandtheunderlyingNeogenelacustrine
deposits of the Seyitgazi volcanic field, south of the Eskisehir fault zone. (b) Lower Miocene
rhyolitic plugs in the Kirka volcanic field (Afyon-Seyitgazi road). (c) Middle Miocene trachytic
plugsanderuptivecentresinandaroundtheCityofAfyonintheAfyon-Suhut-Sandiklivolcanic
field.(d)IgnimbritesandaresurgentdomewithintheGo¨lcu¨kcalderainthehighlyalkalineIsparta-
Go¨lcu¨k-Bucak volcanic field. (e) Bu¨yu¨k Volcano cone and Quaternary lava fields near the
Demirko¨pru¨ReservoirinthewesternpartoftheKulaalkalinebasaltfield.(f)QuaternarybasalticAa
lava flows and the Divlit Tepe cinder cone in the western part of the Kula alkaline basalt field.
(g)Sandalvolcanoconeinthenorth-centralpartofthealkalinebasaltfield.
638 Y. Dilekand S¸. Altunkaynak
tephrite, and phonolite dikes, plugs, and domes crosscut these older trachytic–latitic
volcanic sequences (Figure 4(c)). The Isparta-Go¨lcu¨k-Bucak volcanic field occurs along
the BFZ SW ofLake Egirdir (Figures 2 and3(b);Cengiz et al.2006) and includesPlio-
Pleistocene,thicklybeddedpyroclastic rockswithrhyolite andtrachytic, trachyandesitic
lavas, overlain by trachyte, phonolitic tephrite, and tephritic phonolite (Lefevre et al.
1983;O¨zgu¨retal.1990;Yagmurluetal.1997;Platevoetetal.2008;Elitoketal.2009).In
theGo¨lcu¨kareasouthwestofthecityofIsparta,alargemaarcrater(,2.5kmindiameter)
anditslakeoccupytheedificeoftheGo¨lcu¨kvolcano(Figure4(d)),whichiscomposedof
tephradepositswithsubsidiarylavaflows,anddomes(Platevoetetal.2008;Elitoketal.
2009).Thecrateredgecomprisestephriphonoliticlavaflowsandthecratercentreincludes
twointracaldera-like, trachyticresurgentdomes(Figure4(d)).Thenew40Ar/39Ardating
ofsuccessiveextrusivesequencesoftheGo¨lcu¨kvolcanoindicatesmajoreruptiveevents
between200and24^2Ka(Platevoetetal.2008),markingarenewedactivityinthearea
during the Quaternary, after the Pleistocene volcanism.
The Kula volcanic field immediately west of the Isparta Angle represents the
0 westernmost area of young alkali volcanism in the region and occurs on the northern
1
20 shoulderoftheGedizgraben(Figure2).Thisvolcanicfieldconsistsofaseriesofcinder

ry cones,maars,andvoluminouslavaflowseruptedalonganearlyEW-trendingline,which
a
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n isintersectedby,NS-strikingoblique-slipextensionalfaults(Figure3(c)).Someofthe
a
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4 cinderconesare300mhigh(i.e.DivlitTepe,Figure4(e)–(g))andfeedlavaflowsthatare
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8 nearly22kmlong(Figure3(c)).ThevolcanicactivityintheKulafieldhasbeendatedat
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3: 0.13^0.005Ma (Richardson-Bunbury1996).
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ri Analytical methods
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il We analysed 14 representative rock samples collected from the three volcanic fields we
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, haveinvestigatedinthisstudyformajorandtraceelementconcentrationsandforSr–Nd–
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l Pb isotopic systematics. Samples were powdered in an alumina spex ball mill. Trace
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[ element concentrations were measured using an inductively coupled plasma mass
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By spectrometer (Thermo elemental X-7 series), whereas Nd and Sr isotopic ratios were

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e measuredwithathermalionizationmassspectrometer(VGSector).Isotopeanalyseswere
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lo performed at the University of Rochester. Major elements were analysed in Actlabs in
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ow Ontario,Canada.Thesamplesunderwentlithiummetaborate/tetraboratefusionfollowed
D
by measurement using ICP-optical emission spectrometry). Repeated measurements of
known rock standards indicate that the concentrations of the major elements are within
0.2% and are also certifiedas such by the laboratory.
ForICP–MSanalysesinthegeochemistrylaboratoryattheUniversityofRochester,
25mg powder of the samples was digested and diluted to 100ml in 2% HNO solution
3
with,10ppbinternalstandardofIn,Cs,Re,andBi.Theelementalconcentrationsofthe
sampleswereobtainedbyusingBCR-2andBIR-2(concentrationsfromUSGS)asknown
external standards. The concentrations of the various elements are within 5% error, as
estimatedfromrepeatedmeasurementsofAGV-2(andesite-USGS)andBHVO-2(basalt-
USGS) rock standards, which were run asunknowns.
ForNdandSrisotopicanalyses,between100and200mgofpowderedrocksamples
wasdigestedinHF–HNO acidmixtures.NdandSrisotopesweremeasuredwithaVG
3
Sector multi-collector TIMS using the procedures established in the geochemistry
laboratoryattheUniversityofRochester.Thelaboratoryproceduralblankswere,400pg
for Sr and ,200pg for Nd. No blank correction was necessary for the isotope ratios
measured.
International Geology Review 639
Rock types and petrography
The rock samples from the Seyitgazi-Kırka, Afyon-Suhut-Sandıklı, and Isparta-Go¨lcu¨k-
Bucak volcanic fields comprise both potassic and ultrapotassic rocks (Figures 5 and 6).
The ultrapotassic rocks from all three fields are transitional between lamproitic and
Roman-type(Foleyetal.1987),althoughthelamproiticcompositionismoredominantin
the Isparta-Go¨lcu¨k-Bucak field in the south (Figure 7). In addition to these three NS-
trending volcanic fields in the Isparta Angle region, we evaluated the Kula alkali basalt
(KAB) fieldtothe west for comparison.
The distribution and igneous stratigraphy of the Plio-Pleistocene volcanism in the
IspartaAngleregionhavebeenstudiedpreviouslybyseveralauthors(e.g.Savas¸c¸ınetal.
1997; Yag˘murlu et al. 1997; Alıcı et al. 1998; Aydar 1998; Savas¸c¸ın and Oyman 1998;
Francalanci et al. 2000; Akal and Helvaci 2002; Aydar et al. 2003; C¸oban and Flower
2006; Agostini et al. 2007, 2008; Ersoy et al. 2008; Elitok et al. 2009). The detailed
petrographyandmineralogyofthese volcanicassociationscan befoundinthese papers.
We present below a brief petrographic summary of the main rock units in the three
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Figure 5. Total alkali versus SiO classification diagram (Le Bas et al. 1986) of Neogene–
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QuaternaryunitsfromKAB,Kulaalkalibasaltfield;IGB-KV,Isparta-Go¨lcu¨k-Bucakpotassicrocks;
IGB-UKV,Isparta-Go¨lcu¨k-Bucakultrapotassicrocks;SK-KV,Seyitgazi-Kirkapotassicrocks;SK-
UKV, Seyitgazi-Kirka ultrapotassic rocks; ASS-KV, Afyon-Suhut-Sandikli potassic rocks; ASS-
UKV, Afyon-Suhut-Sandikli ultrapotassic rocks. The blue-dashed curve depicts the Alkali-Sub
alkalisubdivisionfromIrvineandBaragar(1971).
640 Y. Dilekand S¸. Altunkaynak
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y
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a Figure 6. K O versus Na O diagram (using the classification scheme of Peccerillo and Taylor
u 2 2
an (1976)) showing the distribution of analysed-rock samples from the Kula, Isparta-Go¨lcu¨k-Bucak,
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4 Seyitgazi-Kirka,andAfyon-Suhut-Sandiklivolcanicprovincesinthecalc-alkaline,shoshonitic,and
2
8 ultrapotassicfields.Forsymbols,seeFigure5.
2
:
3
0
: VolcanicrocksintheSeyitgazi-Kirkafieldarerepresentedbybasaltictrachyandesite,
t
A
trachyandesite, and rhyolite with associated ignimbrites, which collectively represent
]
m
ri bimodal suites (Keller and Villari 1972). The basaltic trachyandesite lavas consist of
i
ld plagioclase, sanidine, clinopyroxene, orthopyroxene, and magnetite. The rhyolite is
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composed of plagioclase, sanidine, quartz, and biotite. Ultrapotassic rocks in this field
,
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le (SK-UKV)arerepresentedbyalkalinefonoliteandfonolitictephrite,whicharecomposed
i
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[ of leucite, sanidine, aegirine-augite, subordinate biotite, nosean, apatite, and opaque

:
By minerals. All these volcanic rocks are porphyritic in texture (Savas¸c¸ın et al. 1994;

ed Savas¸cın andOyman1998; Francalanci et al.2000).
d
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o The extrusive rocks of the Afyon-S¸uhut-Sandıklı volcanic field are represented by
l
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ow saturated and highly undersaturated rocks. Potassic units (ASS-KV) include shoshonite,
D
trachyte, and trachyandesite, consisting of sanidine, aegirine-augite, plagioclase biotite,
lamprobolite, subordinate apatite, and Fe–Ti oxides. Ultrapotassic units (ASS-UKV)
comprise foidite, leucitite, and lamproite, which consist of leucite, paracelcian, nosean,
perovskite,aegirine-augite,andolivine.Spinel,apatite,calcite,andFe–Tioxidesarethe
most important accessory minerals in these rocks (Yag˘murlu et al. 1997; Aydar 1998;
Savas¸c¸ınandOyman1998;Aydaretal.2003).LamproitesfromtheAfyon-Suhut-Sandikli
fieldincludephlogopite,K-richterite,olivine,diopside,sanidine,apatite,andcalcite(Akal
and Helvaci 2002).
The extrusive sequences in the Isparta-Go¨lcu¨k-Bucak volcanic field are mostly
porphyritic in texture (Guillou 1987; Bilgin et al. 1990). Potassic rocks (IGB-KV) are
trachytic, trachyandesitic, and rhyolitic in composition, and their phenocryst minerals
include sanidine, aegirine-augite, amphibole, plagioclase, biotite, and Fe–Ti oxides.
Ultrapotassic rocks (IGB-UKV) consist of phlogopite, leucite, olivine (with rare Cr-
spinels),clinopyroxene(5–10%),sanidine(5%),apatite, subordinaterichterite,andFe–
Tioxides.Phlogopiteis present either asgroundmass material or asphenocrystphase in
these rocks (C¸oban andFlower 2006).