L\£ATio EAAT)VlK~\ r £WAOYIK~\ ETOlpio\ TO~ xxx:.I, 35 - 45, 2003 Bulletin of the Geological Society of val. xxx:.I, 35 - 45, 2003 35

Geological and geochronological data for and metamorphic units (, Greece): Their tectono-stratigraphic significance

A. PHOTIADES1 and S. KEAYz

ABSTRACT Sikinos and Folegandros islands are comprised of various Mesozoic formations, which are de­ tached on a pre-Alpidic basement. The inherited zircons from both the basement and blueschist series rocks of these islands have been dated by SHRIMP U-Pb geochronology. Zircons from the Sikinos metagranodiorite batholith yielded arange of ages (from ca. 860 to 290 Ma) with aconcentra­ tion of Carboniferous ages consistent with a link to the Pelagonian basement of continental Greece. Ages of igneous zircons from the metabasic and quartz-chlorite schist samples from Sikinos and Folegandros blueschist units are dominantly Jurassic-Triassic (201 ±2 to 223±2 Ma) and Triassic (225±3 Ma) respectively. These ages can be related to the remnants of the Pindos or Vardar Neo­ Tethyan oceanic crust and igneous activity in continental Greece.

llNTRODUCTlON The islands of Sikinos and Folegandros belong to the Cycladic Archipelago of the . The dominant morphological features of these islands are narrow ridges running parallel to the NE-SW and NW-SE directions of the islands respectively. Sikinos and Folegandros form part of the median tectono-metamorphic Attic-Cycladic Complex, which is composed of an Alpine and pre-Alpidic tectonic pile (Papanikolaou, 1984; 1987). At least two main tectonic units can be recognised within the Alpine metamorphic complex of Cycladic islands (Altllerr & Seidel, 1977; o6rr et aI., 1978). An upper unit comprised of unmetamorphosed sedimentary and ophiolitic rocks (R

1 Institute ot Geology and Mineral Exploration, Athens, Greece 2 Department ot Earth Sciences, University ot Queensland, Brisbane, Australia

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2.GEOlOGY AND LITHOSTRATIGRAPHIC SUC­ within the Sikinos basement produced an impre­ CESSION cise age of 275±87 Ma. For this reason the 2.1 Sikinos island crystallisation age of the above metagranodiorite Sikinos consists of a sequence of tectono­ may be re-examined, using the age of precipita­ metamorphic units. At least two major tion of zircon in the intrusive. lithostratigraphic units can be distinguished: a b) The upper unit crops out over the entire basal unit consisting of pre-Alpine dominantly northeastern part of the island. As shown in Figure orthogneissic basement, and an upper tectonic (1 A), a tectonic contact separates the basal unit unit containing Mesozoic formations that both have from the overlying upper unit. Metric size lenticu­ been affected by the Alpine orogeny. lar forms of coarse crystalline actinolitic schist a) The basal unit crops out along the SE coasts mark the tectonic boundary between the two units. of the island, and consists of amedium to coarse­ Overlying the basement is atectonically detached grained metagranodiorite intrusion into gneiss and glaucophane-bearing marble formation, up to 250 schistose-gne iss. mthick. Overlying this formation is a tectonically The metagranodiorite is characterised by a emplaced sequence of glaucophane schist alter­ heterogeneous mineralogical composition, with nating with marble horizons, up to 1300 mthick, local enrichment of feldspar and Ti-biotite with or representing isoclinally folded meta-sediments and without hornblende. In general, the meta-volcanics. metagranodiorite consists ofxenomorphic quartz. The various lithological formations that tec­ plagioclase, K-feldspar (orthoclase, microcline) tonically overlie the detached glaucophane-bear­ with rare perthitic exsolutions in the presence of ing marble can be distinguished from base to top albite and zircon. The gneiss to schistose-gneiss as is described below: consists of lepidoblastic muscovite layers, and Glaucophane schist with cipolin marble (250 rarely intercalations of biotite, as well as to 450 mthick) contains glaucophane, paragonite granoblastic quartz, K-fe!dspar and zircon. The and chloritoid. In the lower parts of the schist metre­ schistose-gneiss differs from the gneiss in hav­ scale lenses of metabasic to greenschist rocks ing a higher proportion of quartz. Overlying these occur, grading to layers of thin-bedded, calc'ltic formations is garnet-mica schist, which is cut by cipolin marble with dolomite. em-sized aplitic dykes. Lower dolomitic marble (up to 200 m thick) The granitoids of this unit, and their country medium-to thick-bedded. Locally ankeritized, thick­ rocks, are polymetamorphics, characterised by bedded marble, crosscut by a dense network of pre-Alpine (Variscan) amphibolite Barrovian fa­ calcite veins and Fe-mineralisation. passing in the cies metamorphism with peak temperatures of 570­ lower parts to thin-bedded cipolin marble. 650 0 Cand pressures of around 5 kbar (Franz et Upwards, glaucophane schist with garnet (200 al.. 1993) and overprinted by two Alpine (Tertiary) to 250 m thick) occupies a large part of the area metamorphic events. This pre-Alpidic amphibolite extending between Chora and Episcopi. At its base, facies metamorphism is characterised by the metabasic lenses (known as prasinites) of metric presence of brown hornblende, passing during the dimensions occur, while in its intermediate and retrograde phase of the Alpine metamorphism to upper parts it alternates with layers of metabasic actinolite and chlorite. However, the transforma­ schist to greenschist and cipolin marble. The tion of white mica into phengite. in these units glaucophane schist is characterised by Na-amphib­ suggests metamorphism up to blueschist facies oles, mainly glaucophane and garnet porphyroblasts. took place during the Eocene (Franz et aI., 1993). The metabasic rocks, WITh medium-crystalline-blas­ Rb-Sr whole-rock measurements by tic texture are composed of albite, epidote. Andriessen et al. (1987) from agranitoid intrusion paragonite, chlorite, apatite and zircon.

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Figure 1. Simplified geological maps of Sikinos (A) and FoJegandros (8) Islands with their tectono-stratigraphic columns and cross-sections (modified trom Avdis &Photiades, 1999). Sikinos (A) 1:alluvial deposits; 2:dolomitic marble; 3:glaucophane schist with metabasalt lenses, eclogite and serpentinite bodies; 4:glaucophane-bearing marble; 5:garnet-mica schist; 6: metagranodiorite and gneiss; 7:tec­ tonic contact (detachment); 8:dated sample. Folegandros (8) 1:Quaternary and Neogene deposits; 2:schist with serpentinite bodies; 3: calcitic marble; 4:glaucophane schist with metabasalt lenses; 5:marble; 6:tectonic contact (detachment); 7:dated sample.

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Table 1. Zircon igneous U-Pb representative analytical results for Sikinos and Folegandros islands a. Data for Sikinos metagranodiorite sample (SK1).

Grain spot U(ppm ThiU %Pb NOPbP''''U ±1a l

b. Data for Sikinos metabasic schist sample (SK2).

Grain spot Uppm ThiU %Pb ""'Pbi2-"U ±1

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c. Data for Folegandros quartz-chlorite schist sample (FL2).

<..~..ra:n spot uppm ThfU %Pb 2{~Pb.r-""U ±1 v =Pbi''''Pb ±1a Ag~ ±1v . Grain area Des mea3ured measured [Mal ~r:'L2-11 397 003 020 109998 0.01621 012575 000193 I 2022.6 322 3 core oz FL2-1.2 348 010 010 1.25009 002448 012718 0002631 2044.1 380 - 3 nm 02 FJ 2-2 f 179 006 066 025516 0006]4 0.00152 000302, 4519 111 1 term;nelJon Ot FU-31 160 011 020 112922 002&32 0.20821 000322 I 2800 I 262 3 nm oz FL2-41 425 042 0.25 005279 000213 0(15305 1)00248 I 237.1 97 1 core oz FU·42 151 086 098 0.07838 000323 005943 000535 2497 101 1 nm oz FL2-43 92 195 254 006482 0.00351 007192 000889 I ?156 11 5 1 Rim oz FL2-51 2g

* Common Pb correction applied: 1· 107Pb correction applied to 106 Pbf3BU age; 3 .1004Pb correction applied to 207Pb/ 206Pb age Des:- Description of internal zircon structure revealed by cathodoluminescence: oz (regular oscillatory zoning); oxc (oscillatory zoned xenocrystic core): uol (unzoned overgrowth low luminescence): ixc (irregularly zoned xenocrystic core); iz (irregularly zoned grain) Note: Italicised data has previously been reported in Keay and Lister's 2002 study on the provenance of Aegean rocks.

The volcanic originated greenschist formation cally contain dispersed pyrite crystals and in vari­ develops large garnet crystals, which are ous parts of the upper members, diasporite pock­ characterised by medium-crystalline to ets up to 1m in scale are observed. Moreover, at microaugen texture, while their structure is mas­ the upper parts, this marble passes gradually to sive and parallel to the schistosity. The microaugens calcschist and then it changes to glaucophane consist of either albite xenoblasts with poikilitic schist, rich in lenticular intercalations of schis­ texture, or by garnet porphyroblasts. Glaucophane, tose eclogitic bodies. In the intermediate mem­ muscovite, paragonite, actinolite, Quartz, zircon bers, it becomes mica-schist bearing and epidote also form part of the paragenesis. microconglomerate horizons rich in glaucophane Marble-schist formation (300 m thick), me­ schist and metavolcanic elongated cobbles. In the dium-thick-bedded, calcitic marble, passing up­ upper members of the formation glaucophane wards to thin-bedded, microcrystalline with Quartz­ schist prevails, rich in eclogite, matabasic to ite lenses, and microbeddings, becoming dolo­ greenschist lenses, which coexist rarely with mitic towards its base. Marble and dolomite 10­ se rpenti nite.

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Upper dolomitic marble (100 mthick) is me­ Calcschist, sericite and mica schists (1 DO-150m dium-thick-bedded to massive and traversed by in thick) overlying marble sequence and in their carbonate and rarely quartz veins. It occurs along upper members serpentinite bodies occur of met­ the northeastern edge of the island. ric dimensions. This unit contains evidence of two separate metamorphic events consisting of a high-pres­ 2.3 Tectonic sure metamorphism (M1) under eclogite to The outcrop-scale structures for Sikinos and glaucophane schist facies conditions, which was Folegandros blueschist units are characterised by overprinted by a greenschist facies Barrovian an initial deformation phase of isoclinal folding, metamorphism (M 2), (Alth err et aI., 1979; with folds having aNW-SE direction (N1300), and Andriessen et aI., 1979; van der Maar et al., 19S1 ; being recumbent towards the SW. The folded rocks Franz et aI., 1993). are affected by synkinematic metamorphism, un­ der blueschist (glaucophane) facies conditions. 2.2 Folegandros island The isoclinal folding and blueschist metamorphism In the southeastern part of the Island (Fig.1 B), is followed by astrong Alpine strain-slip deforma­ an upper unit with low-grade metamorphism ap­ tion phase locally associated with greenschist fa­ pears in tectonic contact with a lower one, which cies conditions and, with axes having the same is characterised by high-grade metamorphism direction as the earlier folding. These tectonic (Sowa 1985; Avdis & Photiades 1999). events deformed the glaucophane schist, and prob­ a} The lower unit, up to 500m in thick, is char­ ably representing tectonic transport from NE to acterized by blueschist sequence where SW, similar to the present plate-kinematics of the glaucophane schists prevail. It also consists of Hellenic arc and trench system (Papanikolaou, greenschists with glaucophane porphyroblastes, 1987). comprising metabasic schist lenses deriving from However, the Folegandros upper unit has not altered basic volcanic rocks with residual porphy­ experienced Alpine high-pressure metamorphism ritic texture and thin-bedded marble intercalation. and it is tectonically separated by the lower The lower parts of the sequence pass to the thin­ blueschist one, via a low angle fault plane with medium-bedded marble through a transitional N400 direction and southeastward dip zone, consisting of marble layers with calcschist, The nature of the contact between the base­ chlorite, actinolite and glaucophane schists Atthe ment and the overlying blueschist and/or base, glaucophane schist with marble alternations unmetamorphosed units is originally interpreted is dominant. In general, these rocks are charac­ as tectonic (Papanikolaou 19S0) or interpreted as terized by the blueschist metamorphic facies of thrust fault (van der Maar &Jansen 1993; Grutter Eocene, passing to greenschist facies during Oli­ 1993; Franz eta!., 1993), while others have inter­ gocene-Miocene. preted the contact as a detachment, normal fault b) The upper unit is characterized by low-grade (Lister et aI., 1984), due to their reactivation dur­ metamorphism formations that from the base to ing the Miocene extensional event, which is also top is composed by micaceous and calcitic explained by collapse of the Aegean crust during schists, thin-medium-bedded marble sequence, granitoid intrusions (see Lee & Lister 1992). up to 400m in thick, where at its base in the non metamorphic biomicrite relics were identified 3. ANALYTICAL METHODS Miliolidae. Ophthalmidiidae and Lagenidae of prob­ The U- Th-Pb composition of zircons from able Jurassic (?) to Cretaceous (?) age (N. Carras basement and blueschist units of Sikinos and determinations in Avdis & Photiades, 1999). Folegandros islands were measured using the

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Australian National University's Sensitive High­ one at 311 ± 1 Ma (n =12) and the other at333 ± mass-Resolution Ion MicroProbes (SHRIMP). 1 Ma (n = 12). The large population at ca. 310 Ma Grains of zircon were separated from well-selected is interpreted as the emplacement age of the samples, using standard magnetic and density orthogneiss proto lith while the older peak repre­ separation techniques. Approximately 100 zircon sents an early-formed inherited component that grains from each sample were randomly hand­ may reflect remobilisation of the magma. The picked to ensure adequate representation of all spread of older ages represent inherited compo­ zircon populations. These zircons were then nents preserved in the igneous zircon grains. mounted in epoxy resin, and sectioned in half by Sample SK2, the Sikinos metabasic schist, polishing, to expose cores and rims. SHRIMP I contains zircons that are irregularly-shaped, pit­ and II ion microprobes were used according to ted and contain numerous inclusions. The zircons current operating procedures to determine U, Th commonly display oscillatory zoning with rare in­ and Pb/U in the sample zircons relative to those in herited cores. Twenty-one analyses of seventeen the 572 Ma SL13 reference zircon. The probe di­ zircon grains yield ages ranging from ca. 230 to ameter varied from 15-30 microns Overnight pump­ 45 Ma (Table 1). The youngest age is from a zir­ ing of the sample chamber minimised the effect of con with unusually high uranium content that grew hydride interferences. Variable discrimination in in a fracture in a pre-existing zircon grain. It is Pb+/U+ was corrected using the established possible that this grain could represent new meta­ power-law relationship between Pb+/U+ and morphic zircon growth. The next youngest zircon UO+/U+ (Claoul-Long et aI., 1995). Small adjust­ grain at ca. 60 Ma is from azircon with 'a mottled ments to the assigned 206Pb/238Pb age of 572 appearance, possibly due to new growth or Ma for SL13 were made per session, to allow for recrystallisation, whereas the other few ages sampling fluctuations arising from its bimodal dis­ younge r than 180 Ma are form unzoned portions tribution (Compston, 1996). The errors in the ages of other,vise oscillatory-zoned grains The first were augmented by a 2.5% uncertainty in the U/ clearly magmatic-appearing, oscillatory-zoned zir­ Pb standard calibration line. For zircons younger con is 180 Ma in age, placing a maximum con­ than 800 Ma, common Pb was estimated by the straint on the timing of sedimentation to form the 207Pb-method (Compston et aI., 1984). schist protolith. This sample also contains adomi­ Zircons were imaged both before and after nant population of Jurassic-Triassic inheritance SHRIMP analysis using cathodoluminescence (CL) at 201 ± 2Ma (n =4) and at 223 ± 2Ma (n =5). techniques. The zircon grains reveal well-devel­ Sample FL2 is strongly foliated quartz-chlorite oped crystal faces, and exhibit oscillatory growth schist with minor calcite from Folegandros, and zoning in CL. shows textural evidence of garnets entirely pseudomorphed by quartz and chlorite. The sample 4. RESULTS contains a mixed, typically detrital, population of The Sikinos metagranodiorite sample (SKi) zircons consisting of rounded, honey-coloured, consists of quartz-K-feldspar-plagi oc lase-biotite, irregular and oscillatory zoned grains, as well as with zircons mainly hosted by biotite and quartz. more angular, elongate to euhedral, colourless and Ages from thirty analyses of twenty-six zircon oscillatory zoned grains. Analyses of nineteen zir­ grains ranged from ca. 860 to 290 Ma (Table 1). cons indicate arange of ages from ca. 2880 to 90 Zircon grains appeared typically magmatic and Ma (Table 1). The youngest age in this population were consistently around 200 ~m in length with has a large uncertainty due to its relatively high regular oscillatory zoning and only rare core struc­ common Pb content (Table 1). The next youngest tures. Two main groups of zircons were identified; age is ca. 140 Ma, and this is taken to represent

Ψηφιακή Βιβλιοθήκη Θεόφραστος - Τμήμα Γεωλογίας. Α.Π.Θ. 42 the protolith age for the Folegandros schist Anum­ metamorphic zircon overgrowths suggests that the ber of zircons contain Triassic inheritance at 225 rocks have experienced acomplicated pre-M1 his­ ± 3(n=5) Ma. tory. For these reasons, it seems more likely that the sediments forming these rocks were depos­ 5. DISCUSSION ited in the Triassic-Jurassic and underwent pre­ The U-Pb geochronology of igneous zircons M1 metamorphism that may be correlated to the from the Sikinos metagranodiorite sample (Table Early Cretaceous event, under epidote-amphibo­ 1) indicates that the granitoid was emplaced dur­ lite facies conditions that recorded in Pelagonian ing the Late Carboniferous (between 330 - 300 domain in continental Greece (Yarwood & Dixon Ma) during the late stages of the Variscan orog­ 1977; Perraki et aI., 2002). These sediments were eny. This supports the suggestion that pre-Meso­ most likely deposited in an active tectonic envi­ zoic basement exists in the Cyclades (e.g., van ronment similar to amodern-day back-arc basin, der Maar and Jansen, 1983). The restricted range accompanied by Triassic volcanism, before they in ages from 330-300 Ma determined forthe intru­ underwent Cretaceous and then Tertiary metamor­ sion of the basement orthogneiss protolith, con· phism associated with the Alpine orogeny. f1icts with previous interpretations of the Pan-Afri­ can basement age for the Cyclades (Henjes-Kunst 6. CONCLUSIONS and Kreuzer, 1982; Andriessen et aI., 1987). The The basal unit in the SE part of the island of interpretation that the ages represent the timing of Sikinos consists of gneiss and schistose gneiss cooling and emplacement of granitoid magma is associated with agran'odiorite intrusive rock. The supported by the metamorphic growth of metagranodiorite sample yields zircon recrystallisation, as has previously been sug­ crystallisation ages varying from ca. 860 to 290 gested (Henjes-Kunst and Kreuzer, 1982). Although Ma suggesting a Devonian to Carboniferous age the granitoid precursors to the gneisses were most of igneous emplacement. These radiometric mea­ likely S-type, there is no evidence to suggest that surements are significant, because they support the zircon ages are entirely inherited (i.e. that no the existence of abasement, which acts as awin­ new zircon growth occurred during granitoid pro­ dow, through which the metamorphosed remnant duction). of pre-Alpidic crystalline basement in the Cyclades The zircon igneous ages from the Sikinos is exposed. The lower unit of Sikinos consists of metabasic and Folegandros Quartz-chlorite schist pre-Alpidic basement, which was recognised also samples, both from blueschist units, (Table 1) are on the islands of los, , and , in dominantly Jurassic-Triassic. These ages repre­ tectonic contact with the overlying Alpine forma­ sent the time at which the zircons formed prior to tions of Mesozoic age (van der Maar, 1981; van metamorphism and place a maximum age con­ der Maar et aI., 1981; Henjes-Kunst & Kreuzer, strain on the timing of sedimentation to form the 1982; Bonneau, 1984; Andriessen et aI., 1987; protoliths to the schists. The protoliths must have Engel and Reischmann 1998; Keay 1998). The pre­ been deposited in the Triassic-Jurassic or possi­ Alpidic basement of Cyclades is thought to link to bly later. This is consistent with fossil evidence of the Pelagonian basement of continental Greece Triassic deposition (Dorr et aI., 1978 and refer­ (Mountrakis 1984; Pe-Piper et aI., 1993; Vavassis ences therein) forthe schists from blueschist units et al., 2000). in the Cyclades. The presumed Eocene timing of The blueschist units in Sikinos and M1 metamorphism (Andriessen et aI., 1979) places Folegandros islands represent isoclinally folded aminimum age constraint on the time of sedimen­ metasediments and metavolcanic ophiolitic relicts, tation, while the recognition of Cretaceous-aged geochemically originating from acid volcanic rocks

Ψηφιακή Βιβλιοθήκη Θεόφραστος - Τμήμα Γεωλογίας. Α.Π.Θ. 43 similar to those in island arcs and basic volcanic Altherr, R., Schliestedt, I., Okrusch, I., Seidel, A. , rocks of MORB affinities (Davis & Dietrich, 1986; Kreuzer, H., Harre, W., Lenz, H., Wendt, I. & Dietrich & Davis, 1986). Wagner, G.A. (1979). Geochronology of high­ Along with the basement, the blueschist units pressure rocks on (Cyclades, Greece). have also undergone the same history of Eocene Contr. Miner. Petrol. 70, 245-255. high-P/low-T metamorphism and Oligo-Miocene Altherr, R., Kreuzer, H, Wendt, I., Lenz, H., Wagner, greenschist to amphibolite facies metamorphism G.A., Keller, J., Harre, W. &Hlphndort, A. (1982). (Altherr et ai., 1979; Andriessen et ai., 1979), prior ALate Oligocene/Early Miocene High Tempera­ to Mio-Pliocene eXhumation as in the case of the ture Belt in the Attic-Cycladic Crystalline Com­ plex (SE Pelagonian, Greece). Geol. Jb. E 23, metamorphic events, which have affected most of 97-164. the Cycladic islands. The Folegandros upper unit Andriessen, PA M., Boelrijk, N.AJ M., Hebeda, has not experienced Alpine high-pressure meta­ E.H., Priem, H.N.A., Verdurmen, EAT. & morphism and it can be correlated with similar Verschure, R.H. (1979). Dating the events of units found in several Cycladic islands and which metamorphism and granitic magmatism in the were emplaced during the Middle-Upper Miocene Alpine orogeny of Naxos (Cyclades, Greece). (Photiades, 2002 and references therein). Contr. Miner Petrol. 69,215-225. The Jurassic-Triassic ages found in zircons Andriessen, PAM., Banga, G. & Hedeba, E.H. from the Sikinos metabasic schist and the (1987). Isotopic age study of pre-Alpine rocks Folegandros quartz-chlorite schist indicate that in the basal units on Naxos, Sikinos and los, these samples may represent the oldest remnants Greek Cyclades. Geologie en Mijnbouw. 66, 3­ of the Pindos or Vardar Ocean. It seems likely that 14. the basalts or ophiolites of the Cycladic blueschist Avdis, V. &Photiades, A. (1999). Geological map units must have been generated in the Triassic of Greece" Folegandros and Sikinos sheet » and then uplifted and eroded to form sedimentary scale 1:50.000. Athens Institute of Geology and sequences, such as the quartz-chlorite schist of Mineral Exploration. Folegandros, during the Jurassic and prior to the Bonneau, M. (1984). Correlation of the Hellenides Eocene metamorphism. nappes in the southeast Aegean and their tec­ Furthermore, these ages reinforce the idea that tonic reconstruction. In J.E. Dixon & A.H.F. Robertson (eds), The Geological Evolution of the possible beginning of oceanic development the Eastern Mediterranean. Spec. PubIs. geol. within the Tethys Hellenic sector began during the Soc. Lond. 17, 517-527. Triassic (Bortolotti et ai., 2001, 2002, 2003; Bonneau, M., Geyssant, J., Kienast, J.R., Lepvrier, Saccani et ai., 2002; 2004). Simultaneously, the G & Maluski, H. (1980). Tectonique et occurrences in the Hellenides of MOR ophiolites mltamorphisme haute pression d'age Eoc8ne of Middle Triassic to Middle Jurassic ages and dans les Hellenides: exemple de 1'~le de Syros IAT to boninitic rocks of suprasubduction zone (Cyclades, Gr8ce). C. R. Acad. Sc. Paris 2910, that occur during the Middle Jurassic are favored 171-174. for the existence of only the Vardar Ocean Bortolotti,V., Carras, N, Chiari, M, Fazzuoli, M., (Bortolotti et al. 2003). Marcucci, M., Photiades, A. & Principi, G. (2003). The Argolis Peninsula in the REFERENCES palaeogeographic and geodynamic frame of Altherr, R & Seidel, E. (1977). Speculations on the the Hellenides .Ofioliti, 28/2,79-94. geodynamic evolution of the Attic-Cycladic Bortolotti, V, Carras, N., Chiari, M., Fazzuoli, M., Crystalline Complex during Alpidic times. In G. Marcucci, M., Photiades, A. & Principi, G. Kallergis (ed.), Proc. Vlth Coli. Geo!. Aegean (2002). New geological obselVations and bio­ Regions, Athens 1977, 347-352, Athens. stratigraphic data on the Argolis Peninsula:

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Ψηφιακή Βιβλιοθήκη Θεόφραστος - Τμήμα Γεωλογίας. Α.Π.Θ.