vorticity analysis in calcite tectonites an example from the attico cycladic massif attica greece abstract although calcite tectonites are widespread in nature their use to quantify flow vorticity is limited we use new micro structural petrofabric and vorticity data to analyse the kinematics of flow in outcrop scale calcite mylonite zones these zones are genetically related to a crustal scale ne directed ductile thrust basal thrust that emplaced the blueschist over the basal unit during the exhumation of the attico cycladic massif calcite microstructures reveal that the last stage of deformation occurred at temperatures 200 300 c achieved by mild heating which is possibly related with the reburial of the basal thrust s footwall vorticity analyses were based on the degree of asymmetry of calcite c axis fabrics as well as on the assumption that the orientation of the long axes of calcite neoblasts within an oblique foliation delineates the direction of instantaneous stretching axis both methodological approaches provide consistent estimates with a simple shear component between 55 and 82 w n 0 76 0 96 the use of the stress axis 1 orientation recorded by twin c axis pairs to quantify vorticity generally gives significantly lower simple shear component comparison of our vorticity estimates with previous estimates inferred from quartz fabrics and rigid porphyroclasts reveals that exhumation related deformation in the nappe pile was steady state

the thrace basin in the rhodope province of ne greece a tertiary supradetachment basin and its geodynamic implications abstract detailed tectonic analysis and geological mapping on the tertiary molassic and volcanosedimentary rocks of the thrace basin in northeastern greece allowed us to reconstruct the structural evolution of the basin and its geotectonic setting as well as the orientation of the regional paleostress field sedimentation was linked with a calc alkaline and locally shoshonitic magmatism associated with the tertiary syn to late orogenic extension in the rhodope province we interpret the molassic tertiary greek part of the thrace basin as a supradetachment basin associated with sedimentary and volcanic infilling five 5 deformational events t1 to t5 have been distinguished during basin evolution from eocene to quaternary time t1 is related to a low angle normal detachment fault zone with a top to the sw to ssw sense of movement and initial basin subsidence during middle late eocene to oligocene time simultaneously with uplift and exhumation of the footwall rhodope metamorphic rocks stacking and crustal thickening in the more external parts of the hellenic orogenic belt have taken place during the same time t2 evolved during oligocene miocene time it was characterized by transpressional tectonics and formation of large strike slip faults and extensional fractures as well as conjugate thrust faults and folds with n nw or s se sense of movement during miocene pliocene time the third t3 event took place it was responsible for the high angle normal faults dismembering the eocene oligocene molassic basin into neogene grabens the t4 event affected the neogene sediments of the basin with minor reverse strike slip faults as well as normal faults the following t5 event is related to large normal active faults they coincided with the active tectonics of the study area defined by the earthquake focal mechanisms

palaeogeography of the western pelagonian continental margin in beotia greece during the cretaceous biostratigraphy and isotopic compositions δ13c δ18o of calcareous deposits the palaeogeography of beotia greece during the cretaceous is outlined on the basis of biostratigraphic evidence derived predominantly from the distribution of rudist bivalves and planktonic foraminifera observed facies trends are evaluated together with carbon and oxygen isotopic compositions of limestones and rudist shells the interaction between global sea level fluctuations and gradual subsidence of the pelagonian continental margin controlled facies distribution during most of the cretaceous the sedimentary record begins with berriasian flysch type deposits that accumulated during incipient eohellenian orogenic movements barremian deposits with similar sedimentological characteristics probably belong to the same tectonostratigraphic unit during aptian cenomanian times terrigenous clastics with a few intercalated marine limestones accumulated in south beotia the fossil content of patch reefs presents important biostratigraphic marks in this terrigenous sequence carbon and oxygen isotopic compositions recorded unstable marine environments and subsequent decrease of continental influx continuous subsidence and rising sea levels are evident in the late turonian onlap of rudist limestones on the eohellenian basement of the ptoon mountains as well as in the interfingering of calcareous slope deposits and basinal globotruncana mudstones of south beotia during late coniacian early santonian a marked regression finally led to a regional emersion and the development of a karst relief this regression is predated by heavy oxygen isotopic compositions in the coniacian limestones which probably resulted from isolation of a larger marine embayment from oceanic circulation the subsequent late santonian campanian transgression flooded all of beotia its sediments lie over allochthonous laterites extended rudist biostromes developed as soon as continental influx ceased as indicated both by the stable isotope compositions of rudish shells and embedding limestones during the late campanian the rather uniform platform type depositional environments differentiated and pelagic sedimentation recurred in south beotia whereas depositional environments to the north remained shallow incipient tectonics movements were responsible for a late maastrichtian emersion of north beotia while basinal conditions persisted in the south the onset of flysch type sedimentation occurred simultaneously during the late paleocene in north beotia as well as in the adjacent parnassus and pindos zones however this important facies transition has not yet been precisely dated in south beotia

using microtremors to assess potential earthquake site response a case study in flushing meadows new york city abstract we have used portable 5 sec period seismometers to record ambient noise across a glacially cut valley filled with unconsolidated holocene sediments the valley located in flushing meadows new york city is surrounded by a densely populated urban environment microtremors were recorded at several sites on and adjacent to the valley while some raw spectra of valley site microtremors exhibit no predominant peaks spectral ratios taken with respect to recordings made at a reference station outside the valley show a sharp peak near 0 8 hz a secondary peak near 2 4 hz is also visible in some of the spectral ratios the frequency of the predominant peak remains constant across the valley width while the relative amplitude decreases systematically from a maximum at the valley center to background levels near the valley edge resonant frequencies predicted by one dimensional modeling of the valley center site response show excellent agreement with observations the 0 8 hz spectral ratio peak is interpreted as the fundamental resonance mode and the 2 4 hz peak is interpreted as the first harmonic of the region above the base of an organic clay layer observed in borehole data the amplification factors implied by the observed spectral ratios are unrealistically high up to 100 which can be attributed to the close proximity of microtremor sources an experiment involving the use of a pile driver source located outside the valley was also performed signals obtained at valley sites during times when the pile driver was in operation show a two fold increase in the amplitude of a spectral peak when compared to signals obtained when the pile driver was turned off this observation gives additional evidence that observed spectral peaks represent soil layer resonances in the valley based on the results of this and other previous studies we conclude that easily obtained microtremor measurements can contribute valuable microzonation and site response information to a study of regional earthquake hazard

temperature time history of subducted continental crust mount olympos region greece in the mt olympos region of northeastern greece continental margin strata and basement rocks were subducted and metamorphosed under blueschist facies conditions and thrust over carbonate platform strata during alpine orogenesis subsequent exposure of the subducted basement rocks by normal faulting has allowed an integrated study of the timing of metamorphism its relationship to deformation and the thermal history of the subducted terrane alpine low grade metamorphic assemblages occur at four structural levels three thrust sheets composed of paleozoic granitic basement and mesozoic metasedimentary cover were thrust over mesozoic carbonate rocks and eocene flysch thrusting and metamorphism occurred first in the highest thrust sheets and progressed downward as units were imbricated from ne to sw 40ar 39ar spectra from hornblende white mica and biotite samples indicate that the upper two units preserve evidence of four distinct thermal events 1 293 302 ma crystallization of granites with cooling from 550 c to 20 km extension in the olympos region was synchronous with extension in the mesohellenic trough and the aegean back arc and concurrent with westward progressing shortening in the external hellenides

littorina and post littorina sedimentological processes in the odra channel in light of multidisciplinary investigations of a sediment core pomeranian bay southern baltic sea abstract a multi proxy study was performed on a gravity core supplemented by acoustics profiles and new radiocarbon dates of macrofossils found in the sedimentation history of the odra channel during the holocene the channel is located in the western part of pomeranian bay and was shaped by a pre odra river that flowed northwest along the peene valley and the eastern part of rugen island during a drop in yoldia sea level the acoustic profiling enabled identification of glacial till the baltic ice lake and littorina sediments the studied core penetrated only marine sediments deposited during littorina and post littorina stages and was the subject of grain size geochemical and diatom analyses the age of appearance of a marine environment in the studied area was estimated at 7200 yrs bp the performed studies enabled division of the core into three phases of environmental evolution the littorina i phase occurred during the time span 7200 6000 yrs bp and is described as a shallow water brackish basin with a low rate of sea level rise and favourable conditions for biogenic production the littorina ii phase dated at 6000 3800 yrs bp reflects a deep marine environment with relatively high salinity and greater current velocity and the last phase post littorina covered the last 3800 yrs bp and turned out to be a strongly energetic environment with decreasing salinity the change from littorina ii to post littorina phase correlates clearly with a change in the acoustic reflection core analyses could be associated with extreme stormy cold events known as bond events dated at 5900 5500 yrs bp and 4200 yrs bp evidencing the final destruction of the odra bank barrier

the basement of the mount athos peninsula northern greece insights from geochemistry and zircon ages the mount athos peninsula is situated in the south easternmost part of the chalkidiki peninsula in northern greece it belongs to the serbo macedonian massif smm a large basement massif within the internal hellenides the south eastern part of the mount athos peninsula is built by fine grained banded biotite gneisses and migmatites forming a domal structure the southern tip of the peninsula which also comprises mount athos itself is built by limestone marble and low grade metamorphic rocks of the chortiatis unit the northern part and the majority of the western shore of the mount athos peninsula are composed of highly deformed rocks belonging to a tectonic melange termed the athos volvi suture zone avz which separates two major basement units the vertiskos terrane in the west and the kerdillion unit in the east the rock types in this melange range from metasediments marbles and gneisses to amphibolites eclogites and peridotites the gneisses are tectonic slivers of the adjacent basement complexes the melange zone and the gneisses were intruded by granites ierissos ouranoupolis and gregoriou the ouranoupolis intrusion obscures the contact between the melange and the gneisses the granites are only slightly deformed and therefore postdate the accretionary event that assembled the units and created the melange pb pb and u pb shrimp dating of igneous zircons of the gneisses and granites of the eastern athos peninsula in conjunction with geochemical and isotopic analyses are used to put athos into the context of a regional tectonic model the ages form three clusters the basement age is indicated by two samples that yielded permo carboniferous u pb ages of 292 6 2 9 ma and 299 4 3 5 ma the main magmatic event of the granitoids now forming the gneiss dome is dated by pb pb ages between 140 0 2 6 ma and 155 7 5 1 ma with a mean of 144 7 2 4 ma a within error identical age of 146 6 2 3 ma was obtained by the u pb shrimp method this late jurassic age is also known from the kerdillion unit and the rhodope terrane the rather undeformed granites are interpreted as piercing plutons the small granite stocks sampled have late cretaceous to early tertiary ages of 66 8 0 8 ma and 68 0 1 0 ma u pb shrimp 62 8 3 9 ma pb pb the main accretionary event was according to these data in the late jurassic since all younger rocks show little or no deformation the age distribution together with the geochemical and isotopic signature and the lithology indicates that the eastern part of the mount athos peninsula is part of a large scale gneiss dome also building the kerdillion unit of the eastern smm and the rhodope massif this finding extends the area of this dome significantly to the south and indicates that the tectonic boundary between the smm and the rhodope massif lies within the avz

early orogenic deformation in the ionian zone of the hellenides effects of slab retreat and arching on syn orogenic stress evolution abstract in this work we report on early orogenic fracture patterns affecting a cretaceous to eocene sedimentary succession exposed in western greece these rocks belong to the cenozoic external hellenides which form the western portion of the aegean orocline the analysis of fracture type orientation and crosscutting relationships provides constraints on the stress and strain patterns during the early stages of orocline formation the fracture patterns in the study area includes early orogenic extensional fractures arranged into two mutually orthogonal sets these developed during progressive burial in the forebulge foredeep system ahead of the advancing compressive front tectonic solution seams at a high angle to bedding postdate these extensional structures solution seams are arranged in different sets oblique to each other and developed in the early stages of thrusting and folding extensional structures and solution seams are oblique to each other their orientation and crosscutting relationships provide evidence for clockwise vertical axis rotation of stress directions with time this is consistent with the progressive arching of the forebulge thrust belt system during progressive slab retreat

kinematics of the central hellenides structural analysis along 24 cross sections crosscutting several windows in the central hellenides provides the sense of nappe movements as well as the location of destroyed oceans lying between the apulian and eurasian continents from the mesozoic orogeny took place in two phases the first phase the eo hellenic phase was initiated by convergence of the apulian and pelagonian plates with west directed subduction and closure of the pindos ocean late jurassic obduction of oceanic lithosphere over the western margin of the pelagonian plate was followed by footwall imbrication mylonites and sheath folds during the late cretaceous uplift was associated with ductile normal faulting at depth and tectonic unroofing at shallow crustal levels the second phase the meso hellenic phase comprised the closure of the ambelakia ocean at the eastern margin of the pelagonian plate and continental subduction along the eastern margin of the apulian plate west directed subduction of the ambelakia ocean was associated with eastward directed ductile thrusting folding and blueschist metamorphism blueschist formed within a simple duplex structure at depth and was subsequently overthrusted in the late eocene onto the olympos microcontinent which acted as a major obstacle to the eastward directed nappe movements up to 150 m thick cataclasites kink folds and a spaced cleavage were formed during the late stage of the continental collision a subduction along the eastern margin of the apulian plate caused kink folding and reimbrication of the western parts of the pelagonian basement since the oligocene the overthickened crust collapsed by means of low angle normal faults

fault structure and related basins of the north aegean sea and its surroundings 1 fault structure and basin evolution in the northern aegean sea and its surroundings have been investigated using bathymetry available onshore and offshore seismic profiles onshore fault patterns from ne greece nw turkey three islands in the aegean sea surface ruptures associated with the 1978 thessaloniki earthquakes gps measurements from north aegean islands and a number of earthquake focal plane solutions and historic seismicity bathymetric and isopach data show that the north aegean trough can be divided into the sporades basin and the saros trough post miocene sediment thickness differences in these basins offset of distinct horizons and frequent seismicity along basin bounding faults indicate that sediment accumulation in the area is fault controlled offshore seismic profiles show that the basin bounding faults are dominantly characterized by apparent normal components as well as strike slip components inferred from typical fault zone profiles additional evidence for existence of strike slip faulting comes from earthquake focal plane solutions we refined the pattern and kinematics of the faults controlling the basins and classified them into two major groups the faults in the first group trend ne sw and ene wsw and are here interpreted to be dominantly right lateral strike slip with normal or reverse components these faults accommodate a similar amount of deformation like the ganos fault and thus represent the westernmost extension of the north anatolian fault zone the faults in the second group trend nw se and are dominantly normal faults with an occasional left lateral component these faults are believed to manifest the termination of the north anatolian fault zone because of the segmentation of the right lateral strike slip faults and the preexisting ne trending tectonic grain the basins are compartmentalized into smaller depocenters basins are orientated with their long axes either parallel to the ne sw to ene wsw trending echelon strike slip faults or in the zone north of the strike slip faults parallel to the nw se trending normal faults the interpretations regarding the kinematics of the faults are consistent with the data compiled from the islands near the faults and from the land in ne greece and nw turkey the northern aegean basins and their spatial relationships to the fault architecture representing the diffused termination of the north anatolian fault system are consistent with the mechanical principles of the strike slip tectonics

retroward extrusion of high pressure rocks an example from the hellenides pelion blueschist nappe nw aegean current tectonic models interpret the hellenides as a unidirectional sw vergent orogenic belt new micro structural and amphibole chemistry analyses show instead that the exhumation of the pelion blueschist nappe pbn of the internal hellenides was achieved by retroward ene directed ductile extrusion which opposes the principal proward orogenic vergence retroward extrusion occurred between two sub parallel major ductile shear zones basal thrust and upper detachment with opposite shear senses which operated simultaneously under blueschist to greenschist facies conditions during the late eocene oligocene because the pbn is tectonically sandwiched between pelagonian basement rocks we suggest that the pbn protolith was accumulated during the late cretaceous in an incipient backarc basin developed above the ne dipping subduction of the pindos ocean beneath the pelagonian microcontinent subsequent apulian pelagonian collision triggered basin inversion and the proward dipping intracontinental subduction that caused the early middle eocene blueschist facies metamorphism followed by the retroward extrusion of the pbn this article is protected by copyright all rights reserved

paleogeographic conditions in the western pelagonian margin in greece during the initial rifting of the continental area the uppermost paleozoic metaclastic sequences of the pelagonian zone in northern greece are connected to the western margin of the zone they represent paleogeographic conditions of a deltaic environment and continental slope which are related to the separation of the paleozoic continent and the initial rifting in the western ophiolite belt in greece the metaclastic sequences define the western external boundary of the pelagonian zone and are used to find the continuation of this boundary in the sporades and oinouses islands in the aegean sea in order to help answer the question of the connection between the hellenides and the taurides in turkey

core complex related extension of the aegean lithosphere initiated at the eocene oligocene transition 1 core complex related stretching of the aegean lithosphere was accommodated in part by the south cyclades shear zone scsz which outcrops on the islands of ios and thera aegean sea greece this paper reports new microstructurally focused 40ar 39ar geochronology that suggests the scsz initiated just before the time of the eocene oligocene transition at 35 ma therefore it is not only miocene extension that led to the tethyan metamorphic core complexes exposed in the cycladic archipelago it is shown here that pervasive top to the south directed ductile shear took place in the scsz for 5 ma during the early oligocene followed by initiation of overprinting north sense shear zones at the time of the oligocene miocene transition at 25 ma this means that modern core complex related extension in the aegean started much earlier than has been previously recognized and that stretching of the aegean lithosphere took place in a distinctly episodic fashion not in a manner that can be described as continuous or progressive the data also mean that the complementary shear sense geometry of the scsz and the north cyclades shear zone ncsz cannot be interpreted as crustal scale boudinage initiated during crustal extension in miocene time since the opposing sense shear zones operated at distinctly different times the paper illustrates the difficulties involved in systematically determining the age of deformation fabrics using 40ar 39ar geochronology and provides a case study that shows the value of carefully designed step heating experiments on microstructurally controlled samples in samples such as these from complex metamorphic tectonites laser fusion or step heating experiments with relatively few steps would have led to erroneous conclusions

tectonic history of a segment of the pelagonian zone northeastern greece continental metamorphic rocks and ophiolitic bodies within the pelagonian zone of the hellenides in the livadi area northeastern greece show repeated periods of deformation that accompany thermal events of early cretaceous and possibly late eocene age structures associated with the earlier deformation indicate thrusting towards the northeast accompanying regional metamorphism of upper greenschist to lower amphibolite facies later structures and a retrogression to lower greenschist facies associated with emplacement of the livadi ophiolitic rocks into their present position are likewise attributed to northeast directed thrusting and probably accompanied the allochthonous movement of the pelagonian basement over the mesozoic platform carbonates of mt olympos emplacement vectors of northeast polarity are inconsistent with tectonic models of the hellenides involving large scale southwestward obduction of mesozoic ophiolites from a single ocean located northeast of the pelagonian zone tectonic models inv

the hellenic ophiolites eastward or westward obduction of the maliac ocean a discussion ophiolitic bodies in the dinaro hellenic mountain belt are among the most important ones in the peri mediterranean alpine chains the characteristic feature of this ophiolitic belt is its middle to late jurassic age of obduction the ophiolitic bodies form two major belts on each side of the pelagonian zone an east pelagonian belt in the vardarian domain and a supra pelagonian ophiolitic belt spo to the west the different hypotheses relative to the origin of the spo present geodynamic evolution models accounting for most of the available data a mid triassic episode of rifting a ladinian jurassic episode of sea floor spreading forming notably the maliac ocean a middle to late jurassic convergent period with subduction and obduction episodes and finally a late episode of tertiary compressional deformation responsible for the westward thrusting of the jurassic ophiolitic nappes over the external zones despite many studies dating from the early 1970s the eastern or western pelagonian origin of these ophiolites especially the spo is still under dispute whatever the adopted hypothesis we consider that the main spo bodies n pindos vourinos othris evia argolis have the same origin because of their geographic continuity and of the similarities in their geological characteristics we propose that this ocean corresponds everywhere to the maliac ocean defined in othris from the well preserved sedimentary oceanic margin and ophiolitic nappes thrust during the late jurassic obduction onto the pelagonian platform there is strong evidence for the existence of two deep basins on both sides of the pelagonian continental ridge during triassic jurassic times they correspond respectively to the vardar area to the east and the pindos domain to the west one of these domains being at the origin of the spo the hypothesis of an eastward emplacement of the spo from the pindos domain is based mainly on sedimentological data from the margin series and on structural analyses of ophiolitic bodies however we conclude the westward obduction of the maliac ocean originating from the vardar area to be the best fitting model this westward model is supported by paleogeographic and structural constraints on regional scale notably the absence of obducted ophiolites in the jurassic series of the koziakas units units attributed to the western pelagonian margin and of the parnassus domain on the eastern side of the pindos basin is difficult to reconcile with an eastward obduction from the pindos domain other observations such as the distribution of ophiolitic detritus in the internal and external zones also promote the westward late jurassic obduction of the maliac ocean our preferred model offers a consistent explanation for the mechanism and timing of the emplacement of the spo as well as providing insight on the origin and emplacement of the vardarian ophiolites following this hypothesis there is no need for a clear boundary between the spo and the west vardarian ophiolitic bodies as they were obducted from the same oceanic basin and during the same jurassic tectonic event in this paper we develop evidence in favor of the eastern pelagonian origin for the spo our adopted model and provide discussion on the data supporting the main alternative hypothesis western origin for the spo

the pelagonian zone in greece a polyphase deformed fragment of the cimmerian continent and its role in the geotectonic evolution of the eastern mediterranean data from macedonia greece correlated with those reported from the pontides turkey indicate that the pelagonian zone of the hellenides represents a fragment of the cimmerian continent which separated the paleo tethys and neo tethys oceans a permo triassic age is suggested for separation of the paleozoic continent and initial rifting in the two oceanic basins as the pelagonian zone represented the northwestern european end of the cimmerian continent the paleo tethys and the northern branch of neo tethys would have been very close to each other on either side of this zone thus both oceans at their european end closed within a short time of each other in the late jurassic early cretaceous the sequential development of the two oceans outlines a model for the geotectonic evolution of the internal hellenides in which a correlation of thrusting and folding phases is also given

the three metamorphic belts of the hellenides a review and a kinematic interpretation summary new results obtained in the three metamorphic belts of the hellenides suggest that each belt has a different structure geotectonic setting and evolution the external metamorphic belt of peloponnesus crete has probably resulted from nappe movement in the vicinity of an evolving island arc system the blueschists occurring within this external belt are allochthonous and have been transported with other nappes over the external carbonate platform of the pre apulian plattenkalk ionian tripolitza almyropotamos units this implies that there was only one true blueschist domain initiated in the cycladic area during early eocene the kinematic interpretation is based on the distinction of a and b structures and on the nature of the shear zones between the different domains especially that between the metamorphic hellenides below and the non metamorphic hellenides above the existence of the probably lower palaeozoic meta sedimentary sequence of kastoria in the northern pelagonian zone indicates that the overlying ophiolite bearing almopias unit has been derived from within the hercynian domain the kastoria sedimentary sequence the ophiolites of vertiskos and the carbonate platform of pangeon are considered to be most likely elements of a probable hercynian orogeny

ductile nappe stacking and refolding in the cycladic blueschist unit insights from sifnos island south aegean sea new geological and structural mapping combined with kinematic and amphibole chemistry analyses is used to investigate the deformation history of the cycladic blueschist unit cbu on sifnos island cyclades aegean sea we concentrate on north sifnos an area characterized by exceptionally well preserved eclogites and blueschists our data show that the early main phase d2 of ductile deformation in the cbu occurred synchronous with the transition from prograde to close to peak retrograde conditions this deformation phase took place at middle eocene and is related to ese directed thrusting that emplaced the metavolcano sedimentary subunit over the marble subunit the subsequent exhumation related d3 deformation is characterized by gently ne plunging folds and ne directed contractional shear zones that formed parallel to the axial planes of folds ne directed shearing occurred under blueschist and transitional blueschist greenschist facies conditions during late eocene oligocene and caused the restacking of the early nappe pile we suggest that a mechanism of ductile extrusion of the cbu in a tectonic setting of net compression could explain better the recorded exhumation related deformation than a mechanism of syn and post orogenic extension our new kinematic results in combination with previous works in the cyclades area reveal a regional scale change in tectonic transport direction from w nw e se at late cretaceous middle eocene to e ne w sw at late eocene oligocene times the observed change in transport direction may be governed by the relative motion of africa with respect to europe during alpine orogeny

the oldest rocks of greece first evidence for a precambrian terrane within the pelagonian zone the pelagonian zone in greece represents the westernmost belt of the hellenide hinterland internal hellenides previous geochronological studies of basement rocks from the pelagonian zone have systematically yielded permo carboniferous ages in this study we demonstrate for the first time the existence of a precambrian crustal unit within the crystalline basement of the pelagonian zone the u pb single zircon and shrimp ages of these orthogneisses vary from 699 7 ma to 713 18 ma which identify them as the oldest rocks in greece these late proterozoic rocks which today occupy an area of c 20 100 km are significantly different from the neighbouring rocks of the pelagonian zone they are therefore interpreted as delineating a terrane named here the florina terrane during the permo carboniferous florina was incorporated into an active continental margin where it formed part of the basement for the pelagonian magmatic arc the activity of this arc was dated in this study by single zircon pb pb ages as having taken place at 292 5 ma and 298 7 ma during the alpine orogeny florina together with the pelagonian zone eventually became a constituent of the hellenides geochemically the florina orthogneisses represent granites formed at an active continental margin because of the late proterozoic ages this late proterozoic active continental margin can be correlated to a pan african or cadomian arc as the gneisses contain inherited zircons of late to middle proterozoic age the original location of florina was probably at the northwestern margin of gondwana similar to other gondwana derived terranes such as east avalonia florina approached the southern margin of eurasia during palaeozoic times where it became part of an active continental margin above the subducting palaeotethys these interpretations further indicate that terrane accretion was already playing an important role in the early pre alpine evolution of the hellenides

tectonic stages along a traverse cross cutting the rhodopian zone greece in a cross section along the rhodopian zone from the greece bulgarian border through the postalpine basins in the xanthi area to thasos island detailed structural mapping and collection of field data enable us to determine a sequence of tectonic stages that affected this area this allows us to propose a model of continental collision during the early eocene ne sw directed movements produced a southwest facing pile of crystalline nappes with internal deformation comprising nw and ne trending isoclinal folds and a ne sw trending stretching lineation after a short time interval nappe movements started again under brittle deformation conditions and produced composite thrust sheets wnw and nne trending chevron folds and thick cataclasite late erogenic uplift and extension caused the formation of nw and ne trending normal faults these faults bounded the oligocene flysch and molasse basins and provided pathways for voluminous magmatic suites this tectonic process was interrupted at the oligocene miocene boundary by a late orogenic compression reflected in nw open folds and dissolution cleavages subsequently differential uplift and subsidence associated with nw and ne trending normal faults has continued up to the present time from the early pliocene new fragmentation and thinning of the crust reflected in wnw listric faults and nne transfer faults has affected the southern parts of the rhodopian zone nappe forming movements are the result of a progressive collisional process involving a kimmerian microcontinent lying between the eurasia and apulia continents in the final stages of this collision uderplating processes led to regional uplift and extension additional extensional movements were related to the formation of the aegean back arc basin caused by the late cenozoic hellenic subduction zone

lateral growth of the continental crust through deep level subduction accretion a re evaluation of central greek rhodope abstract the rhodope massif of northern greece and southern bulgaria has been variably interpreted as a fragment of pre alpine possibly hercynian or precambrian age continental crust that was actively involved in european margin convergent tectonics during the mesozoic and tertiary alternatively we propose that for central greek rhodope the lithological associations and tectonothermal history are consistent with progressive south directed mesozoic crustal growth through deep level subduction accretion a process which involved the near continuous transferral of material of oceanic and continental margin affinity from footwall to hanging wall within a north directed palaeotethyan subduction system central greek rhodope comprises a sequence of schists gneisses and migmatites of wide compositional variation that have undergone intense tectonic intermixing extensive occurrences of marble are associated with amphibolites variably retrogressed eclogites meta gabbros and ultramafic rocks quartzo feldspathic gneisses are abundant throughout the area and are associated with psammitic meta greywacke sequences pelites and quartzites the presence of intercalated marble slivers and thin manganiferous and iron rich siliceous bands is significant the various components exposed in the subduction accretion complex were first underthrust northwards to deep crustal levels subjected to high pressure eclogite facies metamorphism and underplated to the base of the overriding eurasian plate this latter accretion event was characterised by intense southwest directed ductile thrusting and pervasive amphibolite facies metamorphic overprinting it was accompanied by migmatisation and intracrustal melt generation and followed by subduction related magmatism deep level subduction accretion leads to southward growth of the continental margin which in turn leads to subduction retreat allowing the encroachment of the magmatic arc from the north subsequent extensional tectonic exhumation brought the complex up to its present position within the southern margin of eurasia this new interpretation may have implications for other high grade terrains within convergent and collisional systems that have been assumed to represent ancient or pre existing continental crust if so then the importance of deep level subduction accretion as a mechanism of continental crustal growth has hitherto been underestimated