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Turkish Journal of Earth Sciences (Turkish J. Earth Sci.), Vol. 15, 2006, pp. 25-45. Copyright ©TÜB‹TAK

Origin and Tectonic Significance of the Metamorphic Sole and Isolated Dykes of the Divri¤i Ophiolite (Sivas, Turkey): Evidence for Slab Break-off prior to Ophiolite Emplacement

OSMAN PARLAK1, HÜSEY‹N YILMAZ2 & DURMUfi BOZTU⁄3

1 Çukurova University, Department of Geological Engineering, TR–01330 Adana, Turkey (E-mail: [email protected]) 2 Cumhuriyet University, Department of Geophysical Engineering, TR–58140 Sivas, Turkey 3 Cumhuriyet University, Department of Geological Engineering, TR–58140 Sivas, Turkey

Abstract: The Late Cretaceous Divri¤i ophiolite of east-central Anatolia comprises, from bottom to top, an ophiolitic mélange, metamorphic sole and remnants of oceanic . The ophiolitic mélange has been thrust onto the Lower Carboniferous–Campanian Munzur Limestone (Tauride platform), and is in turn tectonically overlain by the metamorphic sole. The metamorphic-sole rocks are represented by amphibolite, plagioclase amphibolite, plagioclase-amphibole schist, plagioclase--amphibole schist and calc-schist. The oceanic- lithosphere remnant exhibits a complete section, excluding volcanic rocks, comprising mantle , ultramafic to mafic cumulates, isotropic and sheeted dykes. Isolated dykes intrude the metamorphic sole and mantle tectonites at different structural levels. The metamorphic-sole rocks beneath the Divri¤i ophiolite can be divided into two groups with distinct geochemical features. The first group is tholeiitic (Nb/Y=0.07–0.18), whereas the second group is alkaline (Nb/Y=1.77–3.48) in chemistry. Chondrite-normalized REE patterns, N-MORB- normalized spider diagrams and tectonic discrimination diagrams suggest that the protolith of the first group was similar to island-arc tholeiitic , whereas the protolith of the second group was more akin to within-plate alkali basalts. The isolated dykes cutting the metamorphic sole and the mantle tectonites exhibit alkaline (Nb/Y=0.68–2.11) character and are geochemically similar to within-plate alkaline basalts. The geochemical evidence suggests that the Late Cretaceous Divri¤i ophiolite formed in a suprasubduction zone tectonic setting to the north of the Tauride platform. During intraoceanic /thrusting, the IAT type and seamount-type alkaline basalts were metamorphosed and accreted to the base of the Divri¤i ophiolite. The alkaline isolated dykes were probably the result of late-stage magmatism fed by melts that originated within an asthenospheric window due to slab break-off, shortly before the emplacement of the Divri¤i ophiolite onto the Tauride platform to the south.

Key Words: isolated dyke, amphibolite, alkaline , tholeiitic magma, slab break-off, Divri¤i, Turkey

Divri¤i Ofiyolitindeki (Sivas, Türkiye) Metamorfik Dilim ve ‹zole Dayklar›n Kökeni ve Tektonik Önemi: Ofiyolit Yerleflmesinden Önce Dalan Levhan›n Kopmas›na ‹liflkin Veriler

Özet: Orta Anadolunun do¤usunda yer alan Geç Kretase yafll› Divri¤i ofiyoliti tabandan tavana do¤ru ofiyolitik melanj, metamorfik dilim ve okyanusal litosfer kal›nt›lar›n› içermektedir. Ofiyolitik melanj tabanda Erken Karbonifer–Kampaniyen yafll› Munzur Kireçtafllar›n› (Toros platformu) bindirmeli bir dokanakla üzerler ve tavanda ise metamorfik dilim taraf›ndan tektonik dokanakla örtülür. Metamorfik dilim amfibolit, plajiyoklasl› amfibolit, plajiyoklas-amfibol flist, plajiyoklas-epidot-amfibol flist ve kalk-flist kayaçlar› ile temsil edilmektedir. Okyanusal litosfer kal›nt›lar› volkanikler hariç tam bir kesit sunarlar ve manto tektonitleri, ultramafik-mafik kümülatlar, izotropik gabrolar ve levha dayklar› ile temsil edilirler. ‹zole dayklar metamorfik dilim ve manto tektonitlerini de¤iflik yap›sal seviyelerde keserler. Divri¤i ofiyolitinin taban›nda yer alan metamorfik dilime ait kayaçlar farkl› jeokimyasal özelliklerine göre iki farkl› gruba ayr›labilirler. Birinci grup toleyitik (Nb/Y=0.07–0.18) ikinci grup ise alkalen (Nb/Y=1.77–3.48) kimyadad›r. Kondrite göre normalize edilmifl nadir toprak element diyagram›, N- MORB’a göre normalize edilmifl örümcek diyagram› ve tektonik ortam belirleme diyagramlar› birinci gruba ait metamorfik kayaçlar›n ada yay› toleyitik bazaltlar›ndan, ikinci gruba ait metamorfik kayaçlar›n ise k›ta içi alkali bazaltlar›ndan türediklerini iflaret etmektedir. Metamorfik dilim ve manto tektonitlerini kesen izole dayklar alkalen (Nb/Y=0.68–2.11) karakterde olup jeokimyasal aç›dan k›ta içi bazaltlar›na benzemektedir. Jeokimyasal veriler Divri¤i ofiyolitinin Geç Kretase’de Toros platformunun kuzeyinde okyanus içi dalma-batma zonu üzerinde

25 ORIGIN OF METAMORPHIC SOLE AND ISOLATED DYKES

olufltu¤unu göstermektedir. Okyanus içi dalma-batma/bindirme s›ras›nda ada yay› toleyitik bazaltlar› ve okyanus adas› alkali bazaltlar›n›n metamorfizmaya maruz kal›p Divri¤i ofiyolitinin taban›na yerleflmifltir. Alkalen izole dayklar ise dalan levhan›n kopmas› ile aç›lan astenosferik pencereden nüfuz eden zenginleflmifl eriyiklerin besledi¤i geç-evre magmatizmas› sonucu Divri¤i ofiyolitinin Toros platformu üzerine yerleflmesinden hemen önce geliflmifltir.

Anahtar Sözcükler: izole dayk, amfibolit, alkali magma, toleyitik magma, levha kopmas›, Divri¤i, Türkiye

Introduction 2002; Çelik & Delaloye 2003; Vergili & Parlak 2005). The Late Cretaceous ophiolites of Turkey define the Isolated microgabbro and dykes intrude the Neotethyan sutures that resulted from the closure of metamorphic soles, mantle tectonites and cumulates of oceanic basins between the Eurasian and Afro-Arabian the Tauride ophiolites. The geochemistry of the dykes plates during the Late Triassic to Late Cretaceous period. shows that they formed in a subduction-related From north to south, these zones are named: (a) environment and indicates their derivation from an the ‹zmir-Ankara-Erzincan, (b) the Inner Tauride, and (c) island-arc tholeiite (IAT) (Parlak et al. 1995; Parlak & the SE Anatolian suture zones (fiengör & Y›lmaz 1981; Delaloye 1996; Dilek et al. 1999; Elitok 2001; Çelik & Görür et al. 1984; Robertson & Dixon 1984; Dilek & Delaloye 2003; Vergili & Parlak 2005). Moores 1990; Y›lmaz 1993; Robertson 2004). Available The latest stage of magmatic activity in a petrographic and geochemical data on ophiolitic suprasubduction zone setting is dominated by the extrusives and intrusives suggest that the Neotethyan eruption of MORB-like or OIB lavas on top of earlier arc- ophiolites of Turkey formed in a suprasubduction zone related tholeiitic lavas. Alternatively, these may environment (SSZ) (e.g., Pearce et al. 1984; Parlak intrude as dykes (Shervais 2001). This has been 1996; Parlak et al. 1996, 2000, 2002, 2004; Yal›n›z et interpreted as off-axis alkaline magmatism representing al. 1996, 2000; Beyarslan & Bingöl 2000; Floyd et al. melts that possibly originated from an asthenospheric 2000; Robertson 2002, 2004; Çelik & Delaloye 2003). window beneath the displaced oceanic lithosphere in the The ophiolites of southern Turkey are located along upper plate (Shervais 2001; Dilek & Flower 2003). two lineaments, namely the Bitlis-Zagros suture zone and Examples of this type of magmatism are found in the the Tauride belt (Figure 1). The Bitlis-Zagros suture zone of (Shervais & Beaman includes complete and undeformed oceanic lithospheric 1991), the ophiolite (Alabaster et al. 1982; remnants of the southern branch of Neotethys, such as Ernewein et al. 1988; Dilek & Flower 2003), and the Troodos in , K›z›lda¤ in Turkey and Baer-Bassit in Tauride ophiolites of Turkey (Lytwyn & Casey 1995; Syria (Figure 1). The Tauride ophiolite belt is Dilek et al. 1999). The late-stage magmas, represented characterized by dismembered ophiolitic units rooted to by isolated dykes in the Tauride ophiolites, range in the north of the Tauride platform (fiengör & Y›lmaz composition from basalts to andesites characteristic of 1981; Andrew & Robertson 2002; Robertson 2002, evolved island-arc tholeiites, and have been interpreted as 2004; Parlak & Robertson 2004). These are, from west having been derived from an asthenospheric window to east, the Lycian, Tekirova, Beyflehir-Hoyran, Alihoca, created by the subduction of a ridge system in the Inner Mersin, Pozant›-Karsant›, P›narbafl› and Divri¤i ophiolites Tauride ocean (Lytwyn & Casey 1995; Dilek et al. 1999). (Figure 1). The ophiolite-related units in this latter belt Çelik (2002) documented exclusively alkaline are characterized, from bottom to top, by ophiolitic dykes cutting the metamorphic sole of the Pozant›- mélanges that tectonically overlie the Tauride carbonate Karsant› ophiolite in southern Turkey. The isolated platform, metamorphic soles and ophiolitic rocks. Well- alkaline microgabbro to diabase dykes of our study area, developed thin metamorphic soles, ranging in thickness which intrude metamorphic soles and oceanic lithospheric from 100 to 400 m, crop out beneath the serpentinized remnants, have not previously been recorded in Turkish mantle tectonites. Protoliths of the metamorphic soles ophiolites. Thus, the Divri¤i ophiolite is an interesting suggest the presence of both tholeiitic and alkaline example of alkaline-type melt generation in the early magma types from various tectonic settings, such as OIB, stages of oceanic lithosphere onto the MORB and IAB (Parlak et al. 1995; Parlak 1996; Çelik .

26 O. PARLAK ET AL.

20°E 24°E 28°E 32°E 36°E 40°E Dinarides 44°N EURASIA

Vardar Zone ophiolites Moesian Platform Black Sea Adriatic Küre ophiolite Rhodope 42°N Sea Massif Mirdita Çangaldağ Ophiolite İstanbul arc Pontides North Anatolian Fault IPO Ankara PO VO Melange 40°N Hellenides Munzur DO Guleman IAESZ ANATOLIA ophiolite İzmir AO Suture Zone East Anatolian Fault Baskil arc Lycian Nappes BHN Zagros T au rid e Bitlis- İspendere- P la MO Kömürhan ophiolite AC tf o Aegean Rhodes r m Sea ARABIA Kızıldağ 36°N Crete Troodos ophiolite ophiolite

0 100 Aegean Trench Cyprus Trench 34°N Mediterranean Sea Dead Sea Fault Km

Figure 1. Distribution of the Neotethyan ophiolites and major tectonic features of the eastern Mediterranean region (from Dilek & Flower 2003). AC– Antalya Complex; IPO– Intra-Pontide Ophiolites; BHN– Beyflehir-Hoyran Nappes; IAESZ– ‹zmir-Ankara-Erzincan Suture Zone; MO– Mersin Ophiolite; PO– Pindos Ophiolite; VO– Vourinos Ophiolite; AO– Alada¤ Ophiolite; DO– Divri¤i Ophiolite.

This paper (1) presents the major- and trace-element et al. (2001). The structurally lowest unit in the study chemistry of the metamorphic sole and isolated dyke area is the Munzur Limestone. The Munzur Limestone is rocks intruding both the metamorphic sole and the present in the carbonate sequence of most of mantle tectonites, (2) investigates possible protoliths of the autochthonous and allochthonous units of the Tauride the material accreted to the base of mantle tectonites belt (Özgül & Turflucu 1984). The base of the Munzur during intraoceanic subduction, and (3) presents the limestone is not exposed in the study area, and this unit evidence for late-stage dyke intrusions fed by melts that is tectonically overlain by the Yefliltaflyayla ophiolitic originated within an asthenospheric window due to slab mélange and above that, the metamorphic sole and break-off, shortly before the emplacement of the Divri¤i Divri¤i ophiolite (Figures 2 & 3). The Munzur Limestone ophiolite onto the Tauride platform in the Late comprises, from bottom to top, algal limestone, oolitic Cretaceous. limestone, algal and foraminiferal limestone, cherty limestone, neritic limestone, rudistic limestone and pelagic limestone (Özgül & Turflucu 1984). The type Geological Setting locality of the Munzur Limestone has yielded an Early The Divri¤i region in east-central Anatolia comprises the Triassic–Campanian age (Özgül & Turflucu 1984); Tauride platform unit, ophiolitic mélange, ophiolite- however, the fossil content of this unit in the study area related metamorphic rocks, ophiolitic rocks, a - indicates an Early Carboniferous–Campanian age (Öztürk sedimentary unit, granitoid rocks and Tertiary cover & Öztunal› 1993; Y›lmaz et al. 2001). sediments (Figure 2). Detailed (1:25000-scale) geological The Yefliltaflyayla mélange tectonically overlies the mapping of the internal of the ophiolitic Munzur Limestone east of Ekinbafl› and Maltepe villages, units of the Divri¤i region was first carried out by Y›lmaz and is tectonically overlain by either metamorphic-sole

27 ORIGIN OF METAMORPHIC SOLE AND ISOLATED DYKES

Palaeocene Maltepe Maastrichtian Divriği granitoid Quaternary alluvium and talus Maastrichtian Saya formation Örenlice formation Campanian volcano-clastic rocks continental detritics Sincan Plio-Quaternary Akmeşe sheeted dyke complex Yamadağı Volcanics unnamed units massive gabbros Eocene-Miocene detritics, carbonates and Galın evaporites layered gabbros Cürek cumulate peridodites N

Divriği Ophiolite Kızılyüce tepe Late Cretaceous tectonites Ekinbaşı metamorphic sole Pengürt thrust fault 0 2 Bizevi Km Yeşiltaşyayla mé lange

E. Carboniferous- Munzur Limestone Karatepe Campanian Güneş Tekke o ’ Keçikaya 39 23 Divriği Soğucak

Tatlıçay river

İnallı

Eskiköy Çetinkaya o ’ Yellice 39 11 37o 37’ 38o 06’

Figure 2. Geological map of the area between Divri¤i and Çetinkaya (Sivas) (modified from Y›lmaz et al. 2001; Y›lmaz & Y›lmaz 2004).

rocks or serpentinized mantle rocks. This unit is also metamorphic sole is cut by unmetamorphosed diabase/ unconformably overlain by Tertiary cover sediments near microgabbro dykes. Divri¤i (Figures 2 & 3). The mélange unit contains The Divri¤i ophiolite is located between Çetinkaya and limestone blocks and metamorphic-rock fragments set in Maltepe in the study area (Figure 2). It displays an almost a serpentinized matrix. The limestone blocks typically complete oceanic lithospheric section, represented by range from tens of metres to several hundred metres in serpentinized mantle tectonites, cumulates, isotropic size. The metamorphic-rock fragments are represented gabbros and sheeted dykes (Figures 2 & 3). Ophiolitic by gneiss, amphibolite, metavolcanic rocks, volcanic rocks and associated sediments are absent. The metaquartzite, calc-schist, and mica schist. transitions from cumulate to isotropic gabbros and from The metamorphic sole lies consistently between the isotropic gabbros to sheeted dykes are gradual, and are mantle tectonites and the Yefliltaflyayla mélange to the exposed along the Tatl›çay river between Günefl and east of Ekinbafl›, and shares sheared contacts with the Çetinkaya (Figure 2). The contacts between the other units above and below (Figure 2). A pronounced regional units of the ophiolite are tectonic (Figure 2). The foliation, mineral lineations and intrafolial folds were exposures of the mantle are located between produced during intraoceanic deformation. The main Pengürt and Maltepe, and are dominated by serpentinized lithology of the metamorphic sole is amphibolite, with that contains dunitic lenses and subordinate subordinate greenschist, marble and metachert. The . A number of deposits within the metamorphic sole exhibits a classic inverted metamorphic dunitic lenses were mined at Pengürt, north of Bizevi and gradient, from amphibolite-facies metamorphic rocks south of Gal›n (Figure 2). The tectonites are intruded by downward into greenschist-facies rocks. The pyroxenite and gabbroic to diabasic dykes at different

28 O. PARLAK ET AL.

AGE UNIT LITHOLOGY EXPLANATION

Quaternary alluvium and talus unconformity Örenlice formation continental clastic rocks unconformity Quaternary Pliocene Yamadağı volcanics andesitic and basaltic lavas and pyroclastites unconformity Miocene unnamed detritics, carbonates and evaporites units Eocene unconformity

Palaeocene Divriği Maastrichtian granitoids granitic rocks

basal conglomerate, gravelstone Campanian Saya -sandstone alternation, pillow lavas Maastrichtian formation with milstone interlayers and reefal limestone unconformity

sheeted dyke complex

massive gabbros

layered gabbros

cumulate containing Divriği Ophiolite , wherlite and clinopyroxenites tectonic contact tectonites containing orthopyroxenite Late Cretaceous layers and dunite pods tectonic contact metamorphic isolated dykes sole tectonic contact mélange containing limestone Yeşiltaşyayla and metamorphics within serpentinized mé lange matrix tectonic contact

L. Carboniferous Munzur recrystalized limestone Campanian Limestone

Figure 3. Columnar section of units in the study area (modified from Y›lmaz et al. 2001; Y›lmaz & Y›lmaz 2004). structural levels. The ultramafic cumulate rocks crop out river to the northeast of Çetinkaya (Figure 2) and are mainly to the south of Pengürt and to the northeast of represented by normal and olivine gabbro. The Yellice (Figure 2). The ultramafic cumulates comprise cumulate gabbro passes transitionally into isotropic dunite, wehrlite, olivine websterite and scarce lherzolite. gabbroic rocks along the Tatl›çay river near Keçikaya and The gabbroic cumulates are observed along the Tatl›çay to the northeast of ‹nalli (Figure 2). It is represented by

29 ORIGIN OF METAMORPHIC SOLE AND ISOLATED DYKES

gabbro and diorite. The sheeted dykes are sparsely pyroxenite dykes have thicknesses ranging from 10 to 25 represented in the upper parts of the isotropic gabbros cm and show granular texture. They are made up and increase in frequency upwards. The dyke thicknesses exclusively of orthopyroxenes, which are recognised in range from 20 to 50 cm. The sheeted dykes are thin section by their first-order colours and lamellar characterized by diabase and microdiorite. structure. In some cases, they contain clinopyroxene The volcano-sedimentary unit, named the Saya exsolution lamellae (Figure 4a). The microgabbro-diabase formation, is well exposed around Yellice and southwest dykes have 30 cm to 1 m thickness and exhibit of Günefl village (Figure 2). The Saya formation intergranular to microgranular-ophitic textures (Figure unconformably overlies the Divri¤i ophiolite, and 4b–d). They are composed mainly of plagioclase, comprises conglomerates at the base in which ophiolite- amphibole and clinopyroxene. The plagioclase shows derived pebbles are dominant. The basal conglomerate extensive saussuritization. The clinopyroxene occurs as passes into alternations of sandstone-mudstone-marl, relict grains surrounded by reaction rims of green to limestone lenses, agglomerate, tuff and spilitic volcanics. green-brown hornblende. In some dykes, biotite is This volcano-sedimentary unit is intruded by basic dykes. observed together with amphibole (Figure 4c). The The fossil content of the limestone lenses yielded a secondary phases include epidote and chlorite, and Campanian-Maastrichtian age (Y›lmaz et al. 2001). accessory minerals are titanite and ilmenite. Calcite and are also found in veins. The granitoid rocks, intruding all of the pre-existing units, are observed at Yellice, Pengürt and Ekinbafl› The metamorphic-sole rocks of the Divri¤i ophiolite (Figure 2). They are A-type granitoid bodies, consisting of comprise four mineralogical associations. These are (1) felsic monzonitic/syenitic and mafic monzogabbroic/ amphibolite, (2) plagioclase amphibolite, (3) plagioclase- monzodioritic rocks and monzodiorite, and are amphibole schist and (4) plagioclase-epidote-amphibole themselves intruded by numerous aplite and diabase schist. The amphibolites have no pronounced foliation, dykes (Y›lmaz et al. 2001; Boztu¤ et al. 2005). The are characterized by granoblastic texture, and are granitoid body cuts the volcano-sedimentary unit of composed exclusively of green hornblende (Figure 4e). The plagioclase-amphibolite rocks have granoblastic Campanian–Maastrichtian age and is unconformably overlain by Eocene basal conglomerates (Do¤an et al. texture and are made up of brown hornblende (65–75 1989; Y›lmaz et al. 2001). Thus, the intrusion age of the %), plagioclase (25–35 %), epidote (< 5 %) and opaque granitoid body is thought to be between Maastrichtian minerals (Figure 4f). The plagioclase is intensely altered and Eocene (Figures 2 & 3). to saussurite and sericite. Quartz, epidote and calcite are observed in veins. The plagioclase-amphibole schist has The Tertiary cover sediments, cropping out between nematoblastic texture and exhibits pronounced foliation Divri¤i and Çetinkaya, range in age from Eocene to due to the preferred orientation of hornblende (70–75 Quaternary and are represented by detrital material, %) and plagioclase (25–30 %) (Figure 4g). The carbonate rocks, evaporites, volcanic rocks and alluvium plagioclase-epidote-amphibole schist has nematoblastic (Figure 2). The base of the cover sediments texture and comprises plagioclase (5–10 %), epidote unconformably overlies the former units and begins with (10–15 %) and green to brown hornblende (70–75 %) an Eocene basal conglomerate in which pebbles of (Figure 4h). granitoid rock, ophiolitic rocks and are dominant (Gürsoy 1986; Do¤an et al. 1989; Y›lmaz et al. 2001). Analytical Techniques

Petrography A total of 29 samples from the metamorphic-sole rocks (17) and isolated mafic dykes (12) were analysed for The isolated dyke intrusions in the mantle tectonites of their major- and trace-element contents. The major- and the Divri¤i ophiolite are widespread and are represented trace-element analyses were carried out in the Mineralogy by microgabbro-diabase and pyroxenite whereas the Department of the University of Geneva (Switzerland). metamorphic sole is only intruded by microgabbro- The major elements were determined by XRF diabase dykes. The dykes have sharp contacts with their spectrometry on glass beads fused from ignited powders host rocks but chilled margins are not observed. The

30 O. PARLAK ET AL.

a b

c d

e f

g h

Figure 4. Microscopic views from the isolated dyke (a-d) and metamorphic-sole rocks (e-h) of the Divri¤i ophiolite.

– to which Li2B4O7 had been added (1:5) – in a gold- Analytical Laboratories in Canada. A subset of 3 samples platinum crucible at 1150 ºC. The trace elements were was also analysed for rare-earth elements (REE) by the analyzed on pressed powder pellets by the same same method in the Minerology Department of the instrument. A subset of 11 samples was analysed for University of Geneva. trace elements (including REE) by ICP-MS at Acme

31 ORIGIN OF METAMORPHIC SOLE AND ISOLATED DYKES

Geochemistry isolated dykes differ from other isolated dykes in the belt The major-, trace- and rare-earth-element contents of the in terms of their alkaline nature. The isolated dykes at metamorphic-sole and isolated dyke rocks from the Mersin, P›narbafl›, Pozant›-Karsant›, Antalya and Köyce¤iz Divri¤i ophiolite are given in Tables 1 to 3. The in southern Turkey have tholeiitic chemistry. metamorphic-sole rocks and the isolated dykes of the The plots in Figure 6a, b illustrate the broad range of Divri¤i ophiolite have a wide range of loss-on-ignition variable Zr/Y and Zr/Ti ratios for the amphibolites. The (LOI) values, ranging from 0.8 to 11.03 (Tables 1 & 2). alkaline amphibolites are characterized by high Zr/Y The wide variation in LOI is a crude measure of the (11.66 to 7.77) and Zr/Ti (0.008 to 0.025) ratios degree of rock alteration and reflects the contribution by whereas the tholeiitic amphibolites have low Zr/Y ratios secondary hydrated and carbonate phases. Humphris & (2.11 to 3) and Zr/Ti (0.01 to 0.013). The isolated dykes Thompson (1978) and Thompson (1991) stated that display similar geochemical behaviour to the alkaline under medium grades of metamorphism involving amphibolites in terms of Zr/Y (4.16 to 10.08) and Zr/Ti hydrous fluids, some degree of selective element mobility (0.015 to 0.065) ratios (Figure 6a, b). Both amphibolites is to be expected, especially for the large-ion-lithophile and dykes display coherent trends in Ti, Y and FeO*/MgO (LIL) elements. Characterization and discrimination of with increasing Zr (Figure 6a–c). The FeO*/MgO variation metamorphic (e.g., amphibolites) and magmatic suites diagram in Figure 6c shows that the internal chemical has been done on the basis of trace elements generally variation is governed largely by mafic fractionation that considered relatively stable (immobile) during alteration, produced a typical Fe-enrichment trend for the alkaline to such as the high-field-strength (HFS) elements and rare- tholeiitic amphibolites and alkaline isolated dykes. The earth elements (Pearce & Cann 1973; Smith & Smith tholeiitic amphibolites appear to define a different 1976; Floyd & Winchester 1978, 1983). Good linear fractionation trend, however, they exhibit geochemical coherence between pairs of stable incompatible elements, features similar to the other data at lower values of Zr. and smooth normalized patterns for REE or a sequence Figure 6d presents two ratios (Ce/Yb vs Zr/Nb) of pairs of incompatible elements mirror pre-metamorphic/ of elements of different degrees of incompatibility. On alteration magmatic compositional variations (Floyd et al. this plot, the degree of partial melting increases from 1996; Winchester et al. 1998; Vergili & Parlak 2005). upper left to lower right. Thus, the protolith of the The amphibolitic rocks from the metamorphic sole alkaline amphibolites is thought to have formed as a exhibit two geochemically distinguishable magma types result of smaller degrees of partial melting than the on the basis of the Zr/Ti versus Nb/Y diagram of Pearce protolith of the tholeiitic amphibolites. The data from the (1996). The first group plots in the alkali- field and isolated dykes plot between those of the alkaline and tholeiitic amphibolites, suggesting that they formed as a is characterized by high concentrations of TiO2 (1.81 to result of smaller degrees of partial melting compared to 5.04 wt %), P2O5 (0.2 to 1.55 wt %), Zr (150 to 339 ppm), Nb (30 to 115 ppm) and Nb/Y (1.77 to 3.48) the tholeiitic amphibolites and higher degrees of partial whereas the second group plots in the tholeiitic-basalt melting compared to the alkaline amphibolites (Figure 5d). These geochemical aspects will be discussed later in field and is represented by low concentrations of TiO2 more detail. (0.61 to 0.99 wt %), P2O5 (0.05 to 0.21 wt %), Zr (38 to 72 ppm), Nb (2 to 4 ppm) and Nb/Y (0.07 to 0.18) The chondrite-normalized REE patterns of the (Figure 5). metamorphic sole rocks and isolated dykes are presented The isolated dykes cutting the metamorphic sole and in Figure 7. The metamorphic-sole rocks display two the mantle tectonites are nepheline normative (Table 2). distinct REE patterns. The alkaline amphibolites exhibit They plot in the alkali-basalt to trachy-andesite field and LREE-enriched patterns (LaN/YbN=8.80 to 21.95) whereas the tholeiitic ones exhibit flat REE patterns contain high values of TiO2 (0.5 to 1.76 wt %), P2O5 (0.11 to 0.49 wt %), Zr (128 to 217 ppm), Nb (17 to (LaN/YbN=0.59 to 1.25). The alkaline amphibolites display 89 ppm) and Nb/Y (0.68 to 2.11) (Figure 5). While the geochemical trends similar to LREE-enriched patterns of Divri¤i subophiolitic amphibolitic rocks exhibit ocean-island basalts (Sun & McDonough 1989) whereas geochemical features similar to metamorphic-sole rocks the tholeiitic amphibolites are more akin to the flat-lying occurring elsewhere in the Tauride belt, the Divri¤i REE patterns of basaltic rocks formed in subduction-

32 O. PARLAK ET AL. Tholeiitic Amphibolites Alkaline Amphibolites 0.99 0.99 0.84 0.61 4.720.200.11 0.21 5.04 0.10 0.12 2.57 0.06 0.05 3.31 0.07 0.84 2.15 0.03 0.87 2.29 0.03 3.32 0.42 0.10 2.83 1.55 0.00 4.08 0.78 0.00 4.06 0.84 0.00 1.81 0.20 3.91 0.09 0.36 4.03 0.08 0.59 0.01 0.60 0.01 0.24 0.12 0.70 0.02 0.65 0.01 41.14 44.1117.27 40.31 16.58 46.59 12.59 41.15 16.30 12.12 41.68 12.23 41.67 46.32 10.53 49.73 16.24 49.84 17.09 43.15 16.99 46.68 13.03 41.23 11.75 42.65 13.68 36.58 14.68 44.98 9.09 44.53 14.32 14.88 100.11 100.04 99.65 100.14 99.06 99.42 100.27 99.60 99.96 99.65 99.13 99.62 99.54 99.23 99.36 99.96 99.92 Major- and trace-element contents of the metamorphic sole rocks. 3 3 5 O 2.79 4.39 2.93 2.05 2.03 2.36 0.76 4.53 4.83 4.85 2.29 2.54 2.06 3.02 2.05 2.88 2.37 2 O 2 O 2 O 1.38 1.52 0.91 0.46 1.41 1.41 0.59 2.04 2.38 2.11 1.07 0.96 1.17 1.30 0.88 1.92 2.40 O 2 2 2 2 Al Cr NiOLOI 0.03 4.95 0.03 4.55 0.02 11.03 0.01 2.41 0.02 1.97 0.01 1.60 0.05 1.82 0.00 1.30 0.00 0.92 0.00 0.80 0.05 1.30 0.03 1.49 0.01 0.91 0.01 1.28 0.03 10.37 0.01 0.83 0.01 0.99 TiO FeO*MnOMgOCaO 11.47Na 0.38 12.08 5.02 9.57 14.38 0.31 4.30 10.85 0.30 9.30 15.39 5.57 15.82 0.16 14.65 7.50 16.01 0.29 10.90 7.74 13.05 11.05 0.28 14.25 6.87 19.92 11.27 0.17 8.63 7.10 11.51 0.20 15.81 2.77 7.29 0.27 12.81 3.26 6.91 15.13 0.24 10.57 3.26 14.63 0.24 11.08 8.03 9.40 13.14 0.22 13.81 8.80 11.60 13.03 0.21 22.39 7.31 0.22 10.70 5.17 11.43 0.42 5.98 0.12 5.75 0.09 5.50 NbZr72YSr698 70URb 476 2727221827271941333426222424132732 2222222 66 2Th 2 22 32Pb 123 2 2 22 32 2283 2222222 Ga 2 13232 38 3Zn 107Cu 29 238Ni 497 4Co 15Cr857 32 252 18V 553 123 2Ce 18 761 23 82Nd 15 181 113 208 119101043393068606123204838223942 252Ba 440 67 13 64 421215145677416253728333027 La 339 19 12 1235 202 12 82S 8 104 531 221Hf 61 1435 331 13 108 67 43 14 16Sc 15 67 219 231 1864As 112 6 320 75 43 53Ti/Y 2 16 95 7 67 134 53 214 17 16 5855 354Nb/Y 58856117 260 182 207 10Zr/Ti 119 41 112 15 25 234 244 1 145 171 2 26 54 19 723 219.5 7 115 55 113 3 333 671 0.07 14 276 220.4 24 117 1 0.01 10 26 10 41 110 10 230.2 15 583 0.11 114 280 327 367 8 54 173 0.01 464 18 201.5 6 254 0.18 85 5 40 23 47 150 2 1048.9 0.01 100 10 108 280 23 1215 75 0.11 546 1118.5 47 242 4 12 39 41 16 1 0.01 613 85 9 99 2.48 4 39 270 23 3 811.7 35 0.01 692 114 66 19 15 132 7 483.4 5 171 25 2.48 6 683 11 589 4 390.6 0.01 104 64 20 3 33 19 126 1776 5 404.0 32 2.79 340 5 77 3 137 9 0.01 30 17 764.6 1230 136 17 2.73 277 175 27 46 3 0.02 770.4 152 48 3 69 50 339 3.48 1019.7 18 22 3 47 286 10 89 0.03 29 1013.4 974 73 3 162 3.24 59 56 834.3 20 377 2 20 45 0.02 6 109 47 11 63 867.6 529 1.81 85 290 368 51 0.01 66 754.9 12 91 147 87 2 1.77 12 229 397 11 39 58 245 0.01 79 42 19 2.75 76 69 254 164 3 11 328 0.01 27 39 2.67 50 22 398 40 16 328 0.01 24 41 2.31 2 2 3 837 48 0.01 89 15 1.85 578 32 2 0.01 2 32 1.84 97 1882 0.01 26 528 8 1219 2 11 779 27 4 20 5 9 Table 1. Metamorphic-Sole Rocks SampleSiO PD-1 PD-2 PD-4 PD-5 PD-19 PD-20 PD-23 PD-24 PD-27 PD-28 PD-29 PD-30 PD-31 PD-32 PD-33 PD-71 PD-72 K P Total

33 ORIGIN OF METAMORPHIC SOLE AND ISOLATED DYKES CIPW Norms Isolated Dikes 0.350.01 0.36 0.02 0.35 0.02 0.42 0.00 0.33 0.01 0.24 0.03 0.47 0.03 0.49 0.03 0.42 0.03 0.14 0.00 0.11 0.00 0.37 0.01 1.41 1.33 1.31 1.76 1.14 1.17 1.31 1.35 1.22 0.50 0.50 1.15 51.1519.62 46.39 15.63 46.12 15.88 49.00 17.56 46.60 16.89 46.87 15.98 49.37 17.87 49.39 17.71 50.22 17.11 51.57 23.74 55.39 24.62 46.20 15.10 Major- and trace-element contents and CIPW norms of the isolated dykes. 3 3 5 O 7.25 2.78 2.81 5.01 3.22 2.70 4.39 4.46 3.93 5.19 7.53 2.71 O 2 2 O O 0.34 1.00 1.15 2.64 1.42 1.41 2.33 2.27 3.32 4.39 0.61 3.26 O 2 2 2 2 2 u355125355898 Cr NiOLOITotalNbZr131YSr88 0.02U 99.41 3.76 132424322523282829384324 Rb 129ThPb 5 19 3 2 281 0.01 100.22Ga 4 3 3.24Zn 2 128Cu2305652182559345 3 3Ni 99.97 3 0.01 290Co 694 12 17 3.32Cr145 13V 217 3Ce 23 99.49Nd41727362525303028455028 0.00 57 83 244 9Ba 17 3475 3.21 18 154La532294043293145467910243 149 10 34 4S 100.37 3334 21 130 16Hf13161 16 0.01Sc 390 70 381 2.17 168As54743 21 27 23 100.52Ti/Y 81 10Nb/Y 140 65 42 20Zr/Ti 15 0.01 238 83 100.18 697 2.15 21 3 33 31 17 81 16 49 652.3 322 159 42 1.46 0.01 100.15 242 5 21 0.02 1.26 763 72 47 85 72 67 331.2 17 389 3 35 10 163 0.71 27 99.95 0.01 262 0.02 10 1.04 16 623 328.4 39 115 204 86 57 100.29 674 25 37 0.71 61 164 0.02 5 0.01 41 234 330.0 1.34 13 682 487 8 99.94 40 234 46 618 0.84 78 24 23 193 0.02 0.00 67 274.5 231 99.58 36 4.75 8 402 16 33 29 288 239 0.68 444 0.00 179 42 76 0.02 306.1 37 1.50 24 188 82 697 30 10 18 103 0.01 53 1076 268 136 0.74 5 281.2 5.04 0.02 62 104 519 189 33 80 88 34 10 309 0.89 288.2 819 17 0.02 8 47 217 6 67 89 19 186 97 205 27 0.86 38 252.9 1318 0.02 18 33 34 25 17 3 62 16 22 21 78.2 36 0.83 443 3 59 20 61 0.02 27 59 117 3 10 70.0 16 22 228 11 2.11 15 0.06 3 49 73 113 287.0 229 14 1627 2.07 74 0.06 8 147 38 56 0.71 0.02 817 9 34 SampleSiO TiO Al PD-3FeO*MnOMgOCaONa PD-6K 7.58P 0.13 6.94 PD-7 0.85 9.33 0.16 7.08 PD-8 12.90 9.48 0.17 PD-10 7.07 12.27 10.27 0.15 PD-11 3.85 5.61 9.06 PD-12 0.12 12.17 7.23 8.22 PD-13 0.12 13.68 7.94 8.53 PD-14 0.12 8.60 5.88 8.90 PD-16 0.12 8.19 6.19Plagioclase PD-17OrthoclaseNepheline 8.05Corundum 72.45 0.11Diopside PD-18 7.92 6.26 2.38WollastoniteOlivine 0.43 0.70 5.05Ilmenite 47.07Magnetite 0.02 0.00 7.70 0.00Apatite 1.59 7.15Total 0.86 6.27 16.14 47.30 0.00 1.71 0.01 1.07 8.28 26.12 0.00 0.53 8.24 0.77 8.67 6.41 100.00 52.90 9.58 0.00 10.03 0.23 23.75 1.65 1.35 0.00 6.82 18.24 100.00 0.81 10.52 43.14 8.12 0.00 1.63 1.37 5.50 0.00 100.01 9.94 0.79 10.80 39.32 10.27 0.00 2.11 22.84 100.01 1.43 0.00 9.91 10.44 0.91 47.99 9.64 100.01 29.00 0.00 1.38 1.28 0.00 15.77 48.69 9.01 0.72 9.49 99.99 12.51 0.00 1.42 1.16 15.35 0.00 10.55 42.61 0.53 100.01 9.11 11.36 0.00 1.54 1.16 22.43 0.00 11.65 48.59 99.99 1.00 12.39 8.28 1.58 0.00 28.54 81.37 1.21 10.88 100.00 0.00 1.04 15.36 5.98 30.97 3.86 0.00 1.43 100.00 1.09 0.59 0.00 9.18 3.03 0.89 23.48 100.02 0.00 0.56 0.00 0.09 1.70 10.13 21.33 99.99 0.29 0.00 10.56 0.55 0.11 0.00 0.22 1.43 1.25 0.84 Table 2.

34 O. PARLAK ET AL. Metamorphic-Sole Rocks Isolated Dikes Trace-element and REE compositions of the subset of samples analysed by ICP-MS. Table 3. SampleRb PD-2BaTh PD-5U 31.10 PD-20Nb 150.50Ta 8.10 PD-23 15.70 0.20Pb 20.80 516.50 0.20Sr508.40 PD-24 < 0.1 1.80Zr55.40 113.70 PD-27 < 0.1Hf 0.1 nd 5.50 nd 631.10 0.70 28.10 0.90Y PD-29 1.80 248.50 695.00 < 0.1La 50.80 79.80 PD-30 0.60 1545.30 nd ndCe 46.00 1.60 4.4Pr1.80 1362.90 nd nd 0.50 10.40 nd PD-3 30.80 1447.80Nd nd 0.90 337.50 5.30 0.77Sm 124.70 nd 1.80 17.70 147.80 nd 8.50 PD-7 7.70 nd 310.30Eu 116.50 15.98 nd 7.00 23.90 1.50 33.60Gd PD-10 2.80 25.10 285.70 3.809.70 6.7Tb nd 1.80 63.20 9.68 nd 345.50 3.30 PD-14 132.60 nd 6.80Dy nd 106.10 nd 4.30 nd 164.70 1.18 490.90 38.12 3.30 6.60Ho 2.70 25.21 PD-16 43.30 83.06 345.80 1.50 18.00 4.28 1220.40Er3.03 45.10 69.40 8.40 146.30 107.10 1.20 PD-18 0.65 0.76 380.80 19.06 215.90 12.00 481.30Tm 6.00 71.10 20.00 nd 128.00 nd 2.05 38.79 40.60 4.69 80.90 1.94 794.70Yb 7.70 173.80 109.90 3.96 0.55 1.00 7.94 3.30 117.90 16.70 7.73Lu 6.00 10.33 106.80 458.90 nd 0.40 26.61 2.5 2.82 64.87 174.50 3.03 159.50 nd 2.12 1.66 15.80 0.50 7.98 0.67 nd 2.20 18.10 78.30 32.60nd 6.27= not 5.20determined; < = below detection limit. 66.00 168.70 6.86 nd 3.00 21.90 3.04 2.02 nd 24.80 1.2 34.29 13.50 1.18 0.84 4.60 0.38 6.16 2.90 1.28 0.39 15.04 7.40 10.80 5.70 4.51 6.30 nd 1.82 75.10 35.50 4.12 8.80 7.84 0.46 0.79 10.69 4.78 2.18 36.30 3.10 4.00 0.33 46.30 5.58 23.50 1 2.55 25.40 9.93 3.40 3.58 nd 4.90 6.50 0.26 7.05 48.00 2.42 22.20 1.68 1.70 0.31 6.60 3.00 5.49 nd 1.00 24.20 1.54 8.02 0.70 23.60 2.77 60.80 32.30 6.30 2.17 1.10 0.61 1.00 1.40 0.21 3.30 6.93 25.30 nd 100.60 1.4 23.50 5.82 7.40 3.50 2.04 48.00 1.04 10.70 5.00 1.06 0.45 34.30 1.14 0.20 3.70 0.44 49.34 27.70 23.88 4.56 2.89 4.4 1.01 nd 5.83 0.79 0.37 4.80 4.66 1.47 0.18 2.20 38.80 0.41 nd 2.17 1.22 2.40 nd 23.63 0.28 5.50 4.11 0.31 1.30 0.80 0.31 nd 1.84 4.40 2.30 6.30 0.21 4.93 0.24 0.83 1.51 0.82 4.02 1.29 2.54 4.90 0.38 4.98 1.26 0.85 0.81 0.26 4.23 2.25 3.41 4.40 1.38 0.30 0.87 1.02 0.32 5.48 2.24 2.06 0.65 0.40 1.12 0.31 3.91 2.46 0.77 0.54 0.34 3.91 0.31 0.47 2.02 0.31

35 ORIGIN OF METAMORPHIC SOLE AND ISOLATED DYKES

1 isolated alkaline amphibolite alkali rhyolite tholeiitic amphibolite phonolite trachy- rhyolite & dacite andesite 0.1 tephri-phonolite

Zr/Ti andesite & basaltic-andesite 0.01 foidite basalt alkali basalt

field of alkaline amphibolites beneath Tauride ophiolites field of tholeiitic amphibolites beneath Tauride ophiolites

field of isolated dikes 0.001 in Tauride ophiolites 0.01 0.1 1 10 100 Nb/Y Figure 5. Rock classification diagram for the metamorphic sole and isolated dykes from the Divri¤i ophiolite (after Pearce 1996). Field of metamorphic soles and mafic dykes from the Tauride ophiolites are from Parlak et al. (1995), Lytwyn & Casey (1995), Dilek et al. (1999), Parlak (2000), Çelik & Delaloye (2003).

50 35000 30000 40 25000 20000 30 15000 Y (ppm)

Ti (ppm) 20 10000 5000 10 0 0 100 200 300 400 0 100 200 300 400 Zr (ppm) Zr (ppm) (a) (b) 6 70 isolated dike 5 alkaline amphibolite 60 Increasing degree of partial melting tholeiitic amphibolite 50 4 40 3

Ce/Yb 30

FeO*/MgO 2 20 1 10 0 0 0 100 200 300 400 0 5 10 15 20 25 30 Zr (ppm) Zr/Nb (c) (d) Figure 6. Characterization of metamorphic-sole rocks and isolated diabase dykes in terms of (a) Zr-Y, (b) Zr-Ti, (c) Zr-FeO*/MgO and (d) Zr/Nb-Ce/Yb.

36 O. PARLAK ET AL.

1000 isolated dike alkaline amphibolite tholeiitic amphibolite field of alkaline amphibolites beneath Tauride ophiolites 100

10

Rock/Chondrite

field of isolated dikes field of tholeiitic amphibolites in Tauride ophiolites beneath Tauride ophiolites 1 La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu

Figure 7. Chondrite-normalized REE patterns of the isolated dykes and metamorphic- sole rocks of the Divri¤i ophiolite (normalizing values are from Sun & McDonough 1989). Data for the metamorphic soles and mafic dykes from the Tauride ophiolites are the same as in Figure 5.

related settings. These two REE patterns are typical of Figure 8. The isolated dykes exhibit enriched multi- other metamorphic soles beneath Tauride-belt ophiolites element patterns compared to N-MORB and the isolated and are interpreted to indicate that basaltic volcanics dykes in other Tauride-belt ophiolites (Figure 8a). They formed in mid-ocean ridge (MORB), within- plate (WPB) exhibit similar patterns to OIB-type basalts in general and island-arc (IAT) settings were metamorphosed during (Figure 8a). But the isolated alkaline dykes seem to intraoceanic subduction in a Neotethyan exhibit small relative Nb depletions with respect to the (Parlak et al. 1995; Lytwyn & Casey 1995; Dilek et al. adjacent elements and LIL-element enrichments such as 1999; Çelik & Delaloye 2003; Vergili & Parlak 2005). Rb, Ba and Th. This may reflect a slight contribution from The isolated dykes have LREE-enriched, differentiated a subduction-modified source to the alkaline melts. The alkaline amphibolites can be directly compared chemically patterns (LaN/YbN=3.17 to 9.42) that are distinct from the REE patterns of isolated dykes elsewhere in the with ocean-island basalt (OIB) and show multi-element Tauride-belt ophiolites (Parlak et al. 1995; Lytwyn & patterns similar to the other analysed amphibolites from Casey 1995; Parlak & Delaloye 1996; Çelik & Delaloye the base of the Tauride-belt ophiolites (Sun & 2003; Vergili & Parlak 2005). The LREE-enrichment McDonough 1989; Parlak et al. 1995; Lytwyn & Casey patterns of the isolated dykes from the Divri¤i ophiolite 1995; Çelik & Delaloye 2003; Vergili & Parlak 2005) display similarity to LREE-enrichment patterns of ocean- (Figure 8b). The tholeiitic amphibolites are different from island basalts (Sun & McDonough 1989). One sample of OIB-type basaltic rocks but exhibit multi-element patterns similar to the other tholeiitic amphibolites beneath the the isolated dykes (PD-3) exhibited lower fractionation Tauride-belt ophiolites (Figure 8c). They are (La /Yb =3.17) and concentrations of REE compared to N N characterized by enrichment of LIL elements (i.e., Rb, Ba, the others (Figure 7); this may be due to different Th, K), Nb depletion, and flat patterns of HFS elements degrees of partial melting at different depths. relative to MORB (Figure 8c). All of this evidence suggests The multi-element diagrams for the isolated dykes, that the protolith of the tholeiitic amphibolites formed in alkaline and tholeiitic amphibolites are presented in a subduction-related setting.

37 ORIGIN OF METAMORPHIC SOLE AND ISOLATED DYKES

1000 6 isolated dike alkaline amphibolite (a) tholeiitic amphibolite 5 100 average OIB

4 field of alkaline amphibolites beneath Tauride ophiolites 10 3 field of tholeiitic amphibolites beneath Tauride ophiolites Sm/Yb OIB

Rock/N-MORB 1 2

field of isolated dikes 1 in Tauride belt ophiolite MORB 0.1 0 (b) 0 2 4 6 8 10 12 14 16 18 100 (a) Ce/Sm

10 10 shoshonites

calc-alkaline lavas

Rock/N-MORB 1 enriched mantle source 1 intra-plate basalts

field of alkaline amphibolites

Th/Yb tholeiitic lavas

subduction beneath Tauride belt ophiolites component 0.1 0.1 (c) isolated dike alkaline amphibolite depleted mantleMORB source tholeiitic amphibolite 100 0.01 0.01 0.1 110 field of tholeiitic amphibolites beneath Tauride belt ophiolites (b) Ta/Yb 10 Figure 9. (a) Sm/Yb versus Ce/Sm diagram and (b) Ta/Yb versus Th/Yb diagram (after Pearce 1982), showing source

Rock/N-MORB 1 characteristics for the metamorphic-sole rocks and isolated dykes of the Divri¤i ophiolite. Fields of OIB and MORB are from Harms et al. (1997). Data for the mafic dykes of the Ba U K Ce Pr P Sm Hf Ti Dy Ho Tm Lu Tauride ophiolites are the same as in Figure 5. 0.1 Rb Th Nb La Pb Sr Nd Zr Eu Gd Y Er Yb

Figure 8. N-MORB-normalized spider diagram for the isolated diabase tholeiitic amphibolites suggest derivation from a more dykes (a), alkaline amphibolite (b) and tholeiitic amphibolites depleted MORB-like mantle source (Figure 9a). Both the (c) of the Divri¤i ophiolite (normalizing values are from Sun tholeiitic and alkaline amphibolites show geochemical & McDonough 1989). Data for the metamorphic-sole rocks and mafic dykes from the Tauride ophiolites are the same as behaviour similar to other amphibolites beneath the in Figure 5. Tauride ophiolites in terms of Ce/Sm and Sm/Yb ratio plots, whereas the isolated dykes are chemically distinct To characterize mantle source regions for the from the amphibolites. Th and Ta show similar degrees of metamorphic-sole and isolated dyke rocks of the Divri¤i enrichment and depletion in most mantle source regions, ophiolite, ratio/ratio plots of incompatible elements were however, Th alone is enriched in mantle wedges above used in Figure 9a, b. The Ce/Sm versus Sm/Yb ratios are subduction zones (Pearce 1982; Alabaster et al. 1982). plotted in Figure 9a together with OIB and MORB Thus, in Figure 9b, MOR basalts and intraplate basalts fall compositions. The high Sm/Yb and Ce/Sm ratios of the in a broad band with a slope of unity. The single sample alkaline amphibolites and isolated dykes suggest that they of tholeiitic amphibolite suggest that it was derived from were derived by melting of an OIB-like enriched mantle a depleted mantle source region modified by the addition source, whereas the low Sm/Yb and Ce/Sm ratios of the of a subduction component, whereas the four samples of

38 O. PARLAK ET AL.

alkaline amphibolites appear to have been derived from their evolution – from birth to resurrection stages. One an enriched mantle source region with no subduction of the most important stages in this cycle appears to be component (Figure 9b). The five samples of isolated the death stage, at which time the high-grade dykes exhibit a shift towards higher Th values and were metamorphic sole is formed and OIB-type enriched probably derived from an enriched mantle source, magmas supply lavas or dykes which invade plutonites modified by the addition of a subduction component and the metamorphic sole prior to ophiolite (Figure 9b). emplacement. A number of ophiolite examples possess these features, including the Coastal Range ophiolite of Tectonic-environment discrimination diagrams based California (the Stonyford Volcanic Complex) (Shervais & on immobile trace elements are presented in Figure 10. Hanan 1989; Shervais & Beaman 1991), the Oman The Zr-Nb-Y triangular plot of Meschede (1986) and the ophiolite (the Salahi volcanics) (Alabaster et al. 1982), Zr/Y versus Zr plot of Pearce & Norry (1979) show and the Pozant›-Karsant› ophiolite in Turkey (the within-plate affinities for the alkaline amphibolites and pyroxenite dykes) (Çelik 2002). Dilek & Flower (2003) isolated dykes, and island-arc affinities for the tholeiitic proposed a tectonic model depicting the late-stage (i.e., amphibolites of the Divri¤i ophiolite. prior to trench-passive margin collision and subsequent ophiolite emplacement) petrogenetic evolution of the Discussion Semail (Oman) ophiolite. The latter authors suggested that the late-stage alkali basalts and dykes of the Salahi Shervais (2001) reviewed the literature on subduction- unit were probably the result of off-axis magmatism fed related ophiolites and proposed an evolutionary scenario by melts that originated within an asthenospheric window that consisted of five stages, overlapping each other in as a result of delamination of subducting lithosphere time and space. In his analysis, he compared ophiolite shortly before the emplacement of the ophiolite onto the evolution to the biological life cycle: namely, the birth, Arabian continental margin. youth, maturity, death and resurrection stages. Each of these stages has its own geological, petrographical and The magmatic and metamorphic processes during the geochemical features. The eastern Mediterranean death stage of the suprasubduction-zone life cycle of the ophiolites possessed most of these characteristics during Divri¤i ophiolite are well constrained by the presence of

Nb*2 20 isolated dike alkaline amphibolite tholeiitic amphibolite 10 A - within plate basalts B - basalts C - mid-ocean ridge basalts A A

Zr/Y

B C

A: WPB B: E-MORB C B C: VAB D D: VAB-MORB 1 Zr/4 Y 10 100 1000 Zr (a) (b)

Figure 10. Tectonomagmatic discrimination diagrams for the metamorphic-sole rocks and isolated diabase dykes of the Divri¤i ophiolite. (a) after Pearce & Norry (1979) and (b) after Meschede (1986).

39 ORIGIN OF METAMORPHIC SOLE AND ISOLATED DYKES

the metamorphic sole and the alkaline isolated dykes. The Casey 1995; Polat et al. 1996; Dilek & Whitney 1997; protoliths of the metamorphic-sole rocks include both Collins & Robertson 1998; Dilek et al. 1999; Parlak & alkaline and tholeiitic magma types. The major-, trace- Robertson 2004), all of the Late Cretaceous Tauride and rare-earth-element geochemistry of the alkaline ophiolites are interpreted as remnants of a single vast amphibolites suggest that these rocks were derived from ophiolitic thrust sheet generated within Neotethys to the an enriched mantle source and do not exhibit a north of the Tauride carbonate platform, called the Inner subduction-zone component on the basis of Th/Yb and Tauride Ocean (Görür et al. 1984). They concluded that Ta/Yb ratios (Figure 9b). Therefore, these rocks are the Tauride ophiolites formed above a N-dipping geochemically similar to seamount-type alkaline basalts. intraoceanic subduction zone (SSZ-type) between the Jurassic–Cretaceous seamount-type alkaline basalts crop Anatolides to the north and the Tauride carbonate out extensively along the Neotethyan sutures of Turkey platform to the south (Figure 11). There are several lines (e.g., Floyd 1993; Parlak et al. 1995; Lytwyn & Casey of evidence, supporting this model of ophiolite 1995; Dilek et al. 1999; Parlak 2000; Rojay et al. 2001; emplacement over the Tauride carbonate platform. These Çelik & Delaloye 2003; Vergili & Parlak 2005). These are as follows: The Central Anatolian ophiolites differ rocks are considered to have accreted to the base of the lithologically and chemically from those emplaced over Neotethyan ophiolites to form metamorphic soles during the Tauride platform. There are number of isolated the Late Cretaceous. The tholeiitic amphibolites of the dismembered ophiolites lying structurally above the K›rflehir and Ni¤de metamorphic massifs (Yal›n›z & metamorphic sole were derived by the metamorphism of Göncüo¤lu 1998; Floyd et al. 2000). Their overall an IAT-type basaltic protolith during intraoceanic stratigraphy is as follows: the lowest part is composed of thrusting/subduction, and show a minor subduction-zone ultramafic rocks overlain by layered and isotropic component based on the Th/Yb and Ta/Yb ratios (Figure gabbros. These are followed upwards by plagiogranite, 9b). These volcanic rocks were presumably detached then dolerite dykes, pillow basalts and acidic extrusives. from the front of the overriding SSZ-type crust and were Epiophiolitic sediments are of middle Turonian–early then underplated and metamorphosed. The alkaline Santonian age according to Yal›n›z (1996). Both ophiolite isolated dykes cutting the metamorphic sole and mantle and overlying sediments were later intruded by tectonites were probably derived from an asthenospheric postcollisional quartz monzonite dated as 81–67 Ma window with some modification by a subduction (Yal›n›z et al. 1999). Geochemical data indicate that the component based on the evidence of Th/Yb and Ta/Yb basalts and dolerites of the volcanic sequence are of IAT ratios (Figure 9b). type, whereas the late dolerite dykes have compositions The Late Cretaceous Neotethyan palaeogeography of more akin to N-MORB (Yal›n›z et al. 1996). By the eastern Mediterranean region involved three different comparison, the Tauride ophiolites display more intact branches of oceanic basins separated by continental ophiolite stratigraphy. A thick slab of residual mantle fragments and platform carbonates. These are northern dominated mainly by harzburgite is tectonically underlain Neotethys, southern Neotethys and the Inner Tauride by dynamothermal metamorphic soles exhibiting inverted ocean (fiengör & Y›lmaz 1981; Robertson & Dixon 1984; metamorphic gradient (from amphibolite to greenschist Görür et al. 1984; Dilek et al. 1999). The Divri¤i facies), well-preserved ultramafic and mafic cumulates ophiolite is located within the Tauride belt in the eastern with a thickness of over 3 km, isotropic gabbros, basaltic part of Central Anatolia. Although there have been pillow lavas and associated sediments. Isolated numerous studies on the origin of the Tauride ophiolites, dolerite/diabase dykes intruded the Tauride ophiolites and their root zone is still debated. Göncüo¤lu et al. (1996- the underlying metamorphic soles. Both the basaltic rocks 1997) and Gürer & Aldanmaz (2002) suggested that the in the volcanic sequence and the isolated diabase dykes Tauride ophiolites formed in a suprasubduction-zone which intrude the ophiolites are of IAT type (Parlak & tectonic setting in the northern branch of Neotethys and Delaloye 1996; Parlak 2000; Elitok 2001; Çelik & were thrust over the K›rflehir-Ni¤de metamorphics Delaloye 2003). Dilek & Whitney (1997) and Okay massifs, then over the Bolkarda¤/Alada¤ carbonate (1989) mentioned the local presence of HP/LT platforms in the Late Cretaceous (Figure 11). According metamorphic rocks along the northern edge of the to some workers (Özgül 1976, 1984; Monod 1977; Bolkarda¤ platform and in Tavflanl› (Kütahya) region, fiengör & Y›lmaz 1981; Lytwyn & Casey 1995; Polat & perhaps due to subduction and later of the

40 O. PARLAK ET AL.

BS ? R/SM CO SC AES ? V IAS N. NEOTETHYS KN P AM ? ITO PO Taurides AP M S. NEOTETHYS A O C 30 N ? ?

subduction zone

Latest Cretaceous

Figure 11. Simplified palaeogeographic sketch map of the eastern Mediterranean during the Late Cretaceous (from Robertson, 2002). A– Antalya, AES– Ankara-Erzincan suture zone, AM– Ankara mélange, AP– Apulia, BS: Black Sea marginal basin, C– Cyprus, CO– Carpathian ocean, IAS– ‹mir-Ankara suture zone, ITO– Inner Tauride ocean, KN– K›rflehir/Ni¤de metamorphic massif, M– Menderes Massif, P– Pelagonian, PO– Pindos ocean, R/SM– Rhodope/Serbo-Macedonian, SC– Sakarya metamorphic massif, V– Vardar.

leading edge of the Tauride platform. Robertson (2002) the forward edge of the overriding SSZ-type crust while noted that, if the K›rflehir/Ni¤de metamorphic rocks seamount alkaline volcanic rocks from the top of the formed part of the Tauride platform, a large amount of subducting plate were metamorphosed to amphibolite would have to be subducted. There is facies as the plate was subducted (Figure 12b). Late-stage very little evidence of regional HP/LT metamorphism magmatic activity prior to the emplacement of the Divri¤i within the K›rflehir/Ni¤de metamorphic units. The ophiolite was represented by the intrusion of isolated ophiolite geology and the geochemical features of the dykes that were generated in an asthenospheric window Tauride ophiolites suggest that an oceanic basin existed in due to slab break-off (Figure 12c). A similar model has the interval from Late Triassic to the Late Cretaceous, and been proposed by Dilek & Flower (2003) for the Salahi was located between the Tauride platform to the south volcanics in the Oman ophiolite. Boztu¤ et al. (2005) and the Anatolides to the north (Figure 11). reported that the A-type Dumluca and Murmana The geological, geochemical and regional tectonic granitoids intrude Late Cretaceous ophiolitic units in the context of the Tauride belt is consistent with the Divri¤i (Sivas) area. They concluded that these granitoids following evolving scenario: The Divri¤i ophiolite formed resulted from the slab break-off stage of the Neotethyan above a north-dipping subduction zone (SSZ setting) convergence system. within the Inner Tauride Ocean (Görür et al. 1984), between the K›rflehir Massif to the north and the Tauride Conclusions platform to the south, in the Late Cretaceous (Figure 12a) (Parlak et al. 2005). During intraoceanic The Divri¤i ophiolite comprises three tectonic units (in subduction, IAT-type volcanic rocks were detached from ascending order): the ophiolitic mélange, the

41 ORIGIN OF METAMORPHIC SOLE AND ISOLATED DYKES

S N

seamount SSZ-type alkali basalt Divriği ophiolite Tauride Kırşehir block block

Late Cretaceous (a)

alkaline & tholeiitic basalt basalt

Tauride Kırşehir block block

Late Cretaceous (b)

Metamorphic sole

Tauride Kırşehir block block asthenospheric window OIB source asthenosphere (c) Late Cretaceous delaminated slab sinking into mantle

Figure 12. A tectonic model for the genesis of the Divri¤i ophiolite and metamorphic- sole rocks. metamorphic sole and the ophiolite unit. Its the tholeiitic amphibolites formed as result of tectonostratigraphy is similar to that found in other parts intraoceanic thrusting in a suprasubduction-zone (SSZ) of the Tauride ophiolite belt. Therefore the Divri¤i basin. ophiolite is thought to have been derived from the Inner The isolated dykes exhibit alkaline (Nb/Y=0.68–2.11) Tauride ocean which was located between the K›rflehir affinity. The major-, trace- and rare-earth-element block and the Tauride platform in the Late Cretaceous. geochemistry of the dykes show that they formed in a The metamorphic-sole rocks comprise two distinct within-plate environment. The Th values of the isolated geochemical groups. The first group is alkaline dykes are higher than normal within-plate alkaline (Nb/Y=1.77–3.48), whereas the second group is magmas; this situation is interpreted as indicating that tholeiitic (Nb/Y=0.07–0.18) in nature. The REE patterns, the isolated dykes were probably derived from an multi-element and tectonomagmatic discrimination enriched mantle source modified by the addition of a diagrams suggest that the alkaline amphibolites formed subduction component. as a result of metamorphism of seamount-type basaltic The late-stage isolated dykes may be a result of off- rocks in an intraoceanic subduction-zone setting, whereas axis magmatism fed by melts that originated within an

42 O. PARLAK ET AL.

asthenospheric window due to slab break-off, shortly (Project No: MMF2003BAP16), and by a Turkish before the emplacement of the Divri¤i ophiolite onto the Academy of Sciences grant to Osman Parlak, in the Tauride passive margin in the Late Cretaceous. framework of the Young Scientist Award Program (TÜBA-GEB‹P/2003-111). The authors would like to thank Abdel Rahman Fowler, Ercan Aldanmaz and Erdin Acknowledgements Bozkurt for their valuable scientific and technical This research was partially funded by Çukurova comments that improved the quality of the present University, Division of Scientific Research Projects manuscript.

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Received 03 August 2005; revised typescript accepted 17 January 2006

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