sequence stratigraphy tectonics and depositional history in eastern thrace basin nw turkey abstract the eastern thrace basin forms the eastern portion of the turkish thrace basin in nw turkey the pre tertiary crystalline basement shows platform and deep basin depositional morphology which results in facies pattern and thickness distribution localization during the early stages of basin development in middle to late eocene time normal fault controlled early and lateral reverse fault controlled later stage tectonic events characterize basin geometry and the present topography respectively the early stage normal faulting caused subsidence and sediment accumulation in the late eocene and early oligocene while later stage tectonic events caused intense deformation and structuration in the early to middle miocene as a result southeastern and northern regions were folded or uplifted and deeply eroded outcrop well log core and reflection seismic studies reveal that the sedimentary succession can be subdivided into five characteristic depositional sequences bounded at their base by unconformities these unconformities were dated using paleontological data the sequence boundaries underlying consecutively sequences 1 2 3 and 5 were dated at 39 5 36 30 and 25 5 ma from older to young in order of succession corresponding to the major erosional breaks between the middle and upper eocene the upper eocene and the lower oligocene the lower and upper oligocene and the upper oligocene and the lower miocene the sequence boundary underlying sequence 4 was determined to lie within the late oligocene succession and as an age designation could not be assigned it was termed intra sequence boundary isb the first two sequences correspond to relative sea level rises and a normal fault controlled tectonism coincides with them reefal carbonates coarse grained clastics and marine shales with abundant volcanic flows or layers represent the sedimentary facies of these two early sequences the third and fourth sequences correspond to either a decreased relative rise of sea level or a relative still stand of sea level and a sediment induced subsidence related to thermal relaxation provides accommodation prograding delta sediments of varying extent constitute the sedimentary packages of these two sequences the depositional sequence 5 which makes up the uppermost part of the sedimentary succession in the basin corresponds to a relative sea level fall and a tectonic style shaped by lateral and inversion faulting characterizes this period nonmarine alluvial fan fluvial channel and various lagoonal deposits constitute the sedimentary facies of this last sequence porous reefal limestones and shallow marine beach sandstones of sequence 1 and deltaic sandstones of sequences 3 and 4 provide good reservoir rocks for the hydrocarbons produced in the study area the marine shales and marls of the second and the third sequences provide good source rocks as they are rich in disseminated organic matter content although the non marine alluvial and fluvial channel deposits of sequence 5 are good reservoirs they lack effective seals the time interval in which sequence 5 was deposited represents a period of major structural and trap development in the basin

acid and basic late neogene volcanism in central aegean sea its nature and geotectonic significance local eruptions of acid volcanic rocks occurred in the central aegean region around the miocene pliocene boundary rhyolites outcrop on the island of antiparos located in the central part of the attic cycladic massif the age of these volcanic rocks ranges from 4 0 to 5 4 m y and chemical and sr isotopic data suggest they were generated by partial melting of the continental crust at the same time along the border of the attic cycladic massif i e on the island of patmos and caloyeri local eruptions of naalkaline basalts occurred the whole of the eruptive activity is interpreted as an expression of the marked tensional tectonic phase which has affected the central aegean area since middle miocene the contrasting nature of the erupted volcanic rocks crustal and sub crustal is attributed to the different thermal state of the lithosphere beneath the two areas as emphasized also by the presence of a wide granitic belt of mainly miocene age which developed in the median sector of the attic cycladic massif

a three dimensional microgeodynamic model of melt geometry in the earth s deep interior 1 this article presents a three dimensional microgeodynamic model of grain melt geometry in partially molten rocks the isotropic unit cell of the partially molten rock is characterized by a face centered cubic symmetry consisting of rhombic dodecahedral grains the variation of surface tension between grain grain and grain melt contacts excites a coupled viscous flow within grains and the interstitial melt leading to a steady state grain melt geometry we obtain the fractional area of intergranular contact contiguity from these models as a function of melt volume fraction between melt fractions of 0 05 and 0 25 comparison with previous results indicates that the contiguity in three dimensional models is lower than in two dimensional models the contrast between two and three dimensional values of contiguity increases at high melt volume fractions we apply our model to the ultralow velocity zones ulvzs and the very low velocity province vlvp in the earth s core mantle boundary the observed seismic signature of the ulvz and vlvp can be explained by peridotite melt volume fractions between 0 08 and 0 12 and between 0 01 and 0 05 respectively in a matrix of elastic properties similar to the preliminary earth reference model

evidence for neotethys rooted within the vardar suture zone from the voras massif northernmost greece abstract three conflicting models are currently proposed for the location and tectonic setting of the eurasian continental margin and adjacent tethys ocean in the balkan region during mesozoic early tertiary time model 1 places the eurasian margin within the rhodope zone relatively close to the moesian platform a tethyan oceanic basin was located to the south bordering a large serbo pelagonian microcontinent model 2 correlates an integral serbo pelagonian continental unit with the eurasian margin and locates the tethys further southwest model 3 envisages the pelagonian zone and the serbo macedonian zone as conjugate continental units separated by a tethyan ocean that was sutured in early tertiary time to create the vardar zone of northern greece and former yugoslavia these published alternatives are tested in this paper based on a study of the tectono stratigraphy of a completely exposed transect located in the voras mountains of northernmost greece the outcrop extends across the vardar zone from the pelagonian zone in the west to the serbo macedonian zone in the east within the voras massif six east dipping imbricate thrust sheets are recognised of these units 1 4 correlate with the regional pelagonian zone in the west and related almopias sub zone by contrast units 5 6 show a contrasting tectono stratigraphy and correlate with the paikon massif and the serbo macedonian zone to the east these units form a stack of thrust sheets with unit 1 at the base and unit 6 at the top unstacking these thrust sheets places ophiolitic units between the pelagonian zone and the serbo macedonian zone as in model 3 additional implications are first that the paikon massif cannot be seen as a window of pelagonian basement as in model 1 and secondly jurassic andesitic volcanics of the paikon massif locally preserve a gneissose continental basement ruling out a recently suggested origin as an intra oceanic arc we envisage that the almopias vardar ocean rifted in triassic time followed by seafloor spreading the almopias ocean was consumed beneath the serbo macedonian margin in jurassic time generating subduction related arc volcanism in the paikon massif and related units ophiolites were emplaced onto the pelagonian margin in the west and covered by late jurassic pre kimmeridgian conglomerates other ophiolitic rocks formed within the vardar zone ano garefi ophiolite unit 4 in latest jurassic early cretaceous time and were not deformed until early tertiary time the vardar zone finally sutured in the early tertiary creating the present imbricate thrust structure of the voras mountains

the significance of graptolite reflectance in regional thermal maturity studies queen elizabeth islands arctic canada abstract variations in reflectance and bireflectance of graptolites taken from the cape phillips formation in the queen elizabeth islands arctic canada are documented graptolites taken from core samples from melville island possess a wide range of reflectance 1 75 3 90 r0max graptolites taken from outcrop samples from the other islands have a much narrower reflectance distribution 0 57 0 81 r0max the latter indicate that the organic matter is in the mature stage of hydrocarbon generation conodont colour alteration indices in strata from arctic canada and in the cape phillips formation in eldridge bay e 79 melville island are low 1 1 5 and agree with the low reflectance of the cape phillips graptolites the higher maximum reflectance values of the melville island graptolites indicate that the host sediments have experienced deeper burial and exposure to elevated temperatures compared to graptolites in the same formation of other islands this study demonstrates that graptolite reflectance can delineate relatively accurately the thermal conditions that sediments enclosing them have experienced and when combined with bitumen reflectance and stratigraphic and structural evidence graptolite reflectance can be useful in assessment of thermal maturity and thickness of eroded section in lower palaezoic successions

cretaceous tertiary structures and kinematics of the serbomacedonian metamorphic rocks and their relation to the exhumation of the hellenic hinterland macedonia greece the kinematic pattern and associated metamorphism of the predominant ductile deformation and the subsequent deformational stages of the serbomacedonian metamorphic rocks and granitoids are presented in terms of peri tethyan tectonics a systematic record of structural and metamorphic data gives evidence of a main top to ene to ese ductile flow of cretaceous age 120 90 ma associated with a crustal stretching and unroofing a subordinate wsw to wnw antithetic sense of movement of the tectonic top is observed in places the associated metamorphic conditions are estimated at 4 5 7 5 kbar and 510 580 c during eocene to miocene times these fabrics were successively deformed by low angle extensional de ductile shear zones with top to ne and sw sense of movement and brittle shear zones of similar kinematic pattern suggesting a transition from ductile to brittle deformation de deformation was accompanied during its later stages by nw se directed shortening we also discuss the relation of this cretaceous tertiary deformation of the serbomacedonian metamorphic rocks with the eocene to miocene ductile top to southwestward crustal shear of the adjacent rhodope crystalline rocks we regard the serbomacedonian and the rhodope metamorphic rocks to represent related metamorphic provinces the most recent exhumation and cooling history of which is bracketed between the eocene and neogene

faulting of lemnos island a mirror of faulting of the north aegean trough northern greece abstract a detailed analysis of the faulting on lemnos island since the miocene was achieved by grouping the recorded meso scale faults and their slickenlines into different groups replacing them with mean representative fault planes mrfp and lineations mrfl and finding the stress tensors driven to the activation of the different mrfp mrfl pairs the oldest recognized fault activity followed the late oligocene n s contraction and uplift d1 event as the latter is implied by e w to ene wsw buckle folds in the upper eocene lower oligocene molasse type sediments it was an early middle miocene strike slip to transpression deformation d2 event associated with n s contraction that also affected the lower miocene volcanogenic rocks the next fault activity was dated in middle late miocene and caused a wnw ese extension d3 event this deformation suggests that a during the late eocene oligocene the north aegean trough was developed as a fore arc basin between the rhodopian magmatic arc and its subduction accretion complex to the south and b during the late oligocene middle miocene the north aegean trough as the whole hellenic hinterland was subjected to the transpression s l deformation and lateral extrusion because of the late collisional processes between apulia and eurasia plates and the retreating of the hellenic orogen from late miocene to pliocene a ne sw extension to right lateral transtension d4 event dominated the north aegean trough indicating that the retreating of the hellenic orogen was completely balanced by a back arc extension the deformation facilitates the westward propagation of the north anatolian fault into the north aegean sea since the early pleistocene the deformation of the north aegean trough is related to a nne ssw back arc extension d5 of the present day hellenic subduction zone and the dominant ene wsw to e w faults along the north aegean trough function as normal to oblique right lateral normal faults

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

an evaluation of criteria to deduce the sense of movement in sheared rocks some of the most useful criteria for the deduction of the sense of shear are summarized for use in areas where unequivocal field evidence is lacking apparently conflicting evidence from rotated pressure shadow regions around porphyroclasts and porphyroblasts is clarified the use of quartz crystallographic fabric asymmetry to deduce the shear sense in the bulk rock should be treated with caution and used only together with detailed microstructural observations

evolution of retreating subduction boundaries formed during continental collision retreating subduction boundaries formed where the rate of subduction exceeds the rate of overall plate convergence appear to be commonly developed features within regions of early or incomplete continent continent collision they are characterized by regional extension within the overriding plate and at their leading edge by thin skinned arcuate thrust belts that are concave towards the overriding plate as is illustrated by examples from the mediterranean region the formation of retreating subduction boundaries is intimately related to the process of continental collision during the early stages of collision retreating subduction boundaries are commonly formed by lateral ejection from zones of crustal shortening along the main collision boundary retreating plate boundaries can also form before the main collision and the associated thrust belts emplaced as precollisional accretionary assemblages because the driving mechanism for retreating subduction boundaries appears to be gravity acting on a dense subducted slab slab pull subduction usually ceases when and only when thick buoyant continental crust enters the subduction zone thus differences in the evolution and duration of retreating subduction systems can be largely attributed to the size and configuration of the deep water regions available to be subducted in some cases retreating subduction boundaries may escape into the open ocean where they form nearly isolated local tectonic systems in these systems the rate of subduction is approximately compensated by the rate of upper plate extension and migration of the system across the oceanic region may be very rapid for example the horseshoe seamounts located about 800 km offshore in the eastern north atlantic may be the active expression of an east dipping westwardly migrating retreating subduction boundary that has evolved from the betic cordillera rif system active in miocene time and may now be progressing across the atlantic at approximately 50 mm yr an analogous situation may be represented by the scotia arc system a westward dipping retreating subduction system located between the south american and antarctic plates which may have escaped into the south atlantic ocean from a zone of crustal shortening in the andes and is now progressing across the atlantic at a rate of about 80 mm yr

inversion of field data in fault tectonics to obtain the regional stress iii a new rapid direct inversion method by analytical means summary a new method for determining the reduced stress tensor with four degrees of freedom the orientations of the three principal stress axes as well as the ratio of principal stress differences using fault slip data or focal mechanisms of earthquakes is presented from a computational point of view the inversion of fault slip data is made in a direct way by purely analytical means as a result the determination process is extremely fast and adaptable on small microcomputers from a physical point of view the method aims at simultaneously i minimizing the angles between theoretical shear stress and actual slip vector and ii having relative magnitudes of shear stress large enough to induce slip despite rock cohesion and friction examples of application to actual fault slip data sets with good or poor variety of fault slip orientations are shown the double significance of the basic criterion adopted results in a more realistic solution of the inverse problem than the single minimization of the shear stria angle

exhumation and doming of the thasos metamorphic core complex s rhodope greece structural and geochronological constraints abstract the thasos island metamorphic core complex s rhodope n aegean sea was generated between 26 and 13 ma progressive extensional tectonics was associated with upwarping of the deeper parts of this core complex to a narrow gneiss dome and with formation of a steep topographic high we present a combined structural microstructural and geochronological study that constrains the deformation time path of progressive extension and exhumation thasos island consists of three superimposed more or less flat lying metamorphic units with downward decreasing geochronologic ages which are separated by two systems of low angle normal detachment surfaces trending nw se the upper unit stayed in supracrustal level since 50 ma representing the upper plate during an early phase of extension not later than 26 23 ma upper levels of the core complex intermediate unit underwent pervasive mylonitization with top to the sw shear from about 21 ma onward the intermediate unit was rigid and top to the sw slip continued at least until 13 8 ma on the discrete detachment surface that separates the core complex from the upper plate yet in the 21 15 ma period deeper levels lower unit still deformed plastically and deformation successively concentrated in zones of high strain and in discrete detachment surfaces that caused decoupling of the lower from the intermediate unit these indicate downdip movements in opposite sense associated with doming of the lower unit at that stage simultaneously the intermediate unit was fragmented on high angle normal faults that sole into the dome bounding detachment surface and roof into the core complex bounding detachment surface these faults confine tilt blocks that are arranged around the lower unit gneiss dome doming of the core complex occurred simultaneously with subsidence of basins located on the upper plate

mesozoic tertiary structural evolution of an extensional gneiss dome the kesebir kardamos dome eastern rhodope bulgaria greece the tectonic evolution of the rhodope massif involves mid cretaceous contractional deformation and protracted oligocene and miocene extension we present structural kinematic and strain data on the kesebir kardamos dome in eastern rhodope which document early tertiary extension the dome consists of three superposed crustal units bounded by a low angle nne dipping detachment on its northern flank in bulgaria the detachment separates footwall gneiss and migmatite in a lower unit from intermediate metamorphic and overlying upper sedimentary units in the hanging wall the high grade metamorphic rocks of the footwall have recorded isothermal decompression direct juxtaposition of the sedimentary unit onto footwall rocks is due to local extensional omission of the intermediate unit structural analysis and deformational metamorphic relationships give evidence for several events the earliest event corresponds to top to the sse ductile shearing within the intermediate unit interpreted as reflecting mid late cretaceous crustal thickening and nappe stacking late cretaceous palaeocene eocene late tectonic to post tectonic granitoids that intruded into the intermediate unit between 70 and 53 ma constrain at least pre latest late cretaceous age for the crustal stacking event subsequent extension related deformation caused pervasive mylonitisation of the footwall with top to the nne ductile then brittle shear ductile flow was dominated by non coaxial deformation indicated by quartz c axis fabrics but was nearly coaxial in the dome core latest events relate to brittle faulting that accommodated extension at shallow crustal levels on high angle normal faults and additional movement along strike slip faults radiometric and stratigraphic constraints bracket the ductile then brittle extensional events at the kesebir kardamos dome between 55 and 35 ma extension began in paleocene early eocene time and displacement on the detachment led to unroofing of the intermediate unit which supplied material for the syn detachment deposits in supra detachment basin subsequent cooling and exhumation of the footwall unit from beneath the detachment occurred between 42 and 37 ma as indicated by mica cooling ages in footwall rocks and extension proceeded at brittle levels with high angle faulting constrained at 35 ma by the age of hydrothermal adularia crystallized in open spaces created along the faults this was followed by late eocene oligocene post detachment overlap successions and volcanic activity crustal extension described herein is contemporaneous with the closure of the vardar ocean to the southwest it has accommodated an earlier hinterland directed unroofing of the rhodope nappe complex and may be pre cursor of and or make a transition to the aegean back arc extension that further contributed to its exhumation during the late miocene this study underlines the importance of crustal extension at the scale of the rhodope massif in particular in the eastern rhodope region as it recognizes an early tertiary extension that should be considered in future tectonic models of the rhodope and north aegean regions

extension in compressional orogenic belts the eastern alps extension in the eastern alps encompasses the following 1 extension accompanying simple shear crustal stacking subhorizontal stretching occurs along flat lying foliations and regionally consistent stretching lineations with associated high strains on a local scale stretching results from extrusion of ductile sediments squeezed between rigid basement blocks basement blocks during thrust sheet imbrication the overall geometric effect is crustal thickening 2 classical extensional tectonics extension first occurs as a consequence of accretion and underthrusting of continental and oceanic material and represents gravitational adjustment of an unstable orogenic wedge extension then occurs as a consequence of terminal continental collision and is accommodated by lateral extrusion of crustal of crustal blocks the overall geometric effect is crustal thinning extension is generally oriented subparallel to the strike of the orogen

syn metamorphic nappe complex in the rhodope massif structure and kinematics mylonitic gneisses of the bulgarian and greek rhodope were deformed under medium pressure type metamorphism the kinematic information contained in these gneisses shows that shear deformation occurred during development of a nappe complex lithologies and metamorphic histories allow a lower footwall and an upper hanging wall terrane to be distinguished that define a crustal scale duplex as oceanic crust is involved collision between two continental units with subsequent crustal thickening is inferred the blocks would be moesia to the north and the lower rhodope promontory to the south which collided in the mesozoic to early cenozoic the nappe complex is characterized by south to southwestward foreland directed piling up and is associated with both coeval and subsequent extension the late extension is associated with the establishment of a high temperature low pressure metamorphic gradient and plutonism that predates but makes a transition to the lithospheric extension of the aegean arc

u pb and 40ar 39ar geochronology of the symvolon granodiorite implications for the thermal and structural evolution of the rhodope metamorphic core complex northeastern greece north aegean continental lithosphere was thickened by southwest vergent thrusting and continental subduction within the alpine collisional orogen but has subsequently been greatly extended on a northeast southwest axis in the back arc of the hellenic subduction zone crosscutting relationships with two granodiorite bodies emplaced at 31 33 ma the xanthi and eastern vrondou plutons constrain a pre mid oligocene origin of alpine convergent structures in northeastern greece post alpine thinning of the north aegean nappe pile began in earliest miocene time and has been accommodated by a succession of distinct structural systems the earliest of these the symvolon shear zone appears to represent a midcrustal coaxial rupture of the falakron marble series a carbonate platform 5000 m thick that was subducted northeastward beneath high grade rocks of the rhodope metamorphic province in late alpine time zircon and titanite u pb dates and hornblende 40ar 39ar dates obtained in this study constrain the intrusion and incipient mylonitization of the symvolon or kavala granodiorite within the symvolon shear zone at 21 22 ma following its emplacement the symvolon body resided at temperatures between 300 c and 500 c for 5 7 m y during which coaxial deformation may have continued within a widening symvolon rupture the strymon valley detachment a regionally south west dipping low angle normal fault succeeded the symvolon shear zone in middle miocene time southwestward displacement of the serbo macedonian gneiss complex by as much as 80 km in the hanging wall of this detachment facilitated the unroofing of the rhodope metamorphic core complex including the falakron marble series and several tertiary plutons in its footwall biotite and k feldspar 40ar 39ar dates from 11 1 0 2 ma to 15 5 0 3 ma yielded by symvolon granodiorite samples document the cooling of the rhodope core complex below 150 c 300 c during its southwestward progressive exhumation in the footwall of the strymon valley detachment

u pb zircon geochronology of the paleogene neogene volcanism in the nw anatolia its implications for the late mesozoic cenozoic geodynamic evolution of the aegean abstract the northern aegean region was shaped by subduction obduction collision and post collisional extension processes two areas in this region the rhodope thrace biga peninsula to the west and armutlu almacik nallihan the central sakarya to the east are characterized by extensive eocene to miocene post collisional magmatic associations we suggest that comparison of the cenozoic magmatic events of these two regions may provide insights into the late mesozoic to cenozoic tectonic evolution of the aegean with this aim we present an improved cenozoic stratigraphy of the biga peninsula derived from a new comprehensive set of u pb zircon age data obtained from the eocene to miocene volcanic units in the region the compiled radiometric age data show that calc alkaline volcanic activity occurred at 43 15 ma in the biga peninsula 43 17 ma in the rhodope and thrace regions and 53 38 ma in the armutlu almacik nallihan region which are slightly overlapping we discuss the possible cause for the distinct cenozoic geodynamic evolution of the eastern and western parts of the region and propose that the rhodope thrace and biga regions in the north aegean share the same late mesozoic to cenozoic geodynamic evolution which is consistent with continuous subduction crustal accretion southwestward trench migration and accompanying extension all preceded by the late cretaceous paleocene collision along the vardar suture zone in contrast the armutlu almacik nallihan region was shaped by slab break off and related processes following the late cretaceous paleocene collision along the izmir ankara suture zone the eastern and western parts of the region are presently separated by a northeast southwest trending transfer zone that was likely originally present as a transform fault in the subducted tethys oceanic crust and demonstrates that the regional geodynamic evolution can be strongly influenced by the geographical distribution of geologic features on the subducting plate

active tectonics of the north and central aegean sea summary in this paper we examine the connection between the westward motion of turkey relative to europe and the extension in and around the aegean sea the principal new data available since the last attempt to synthesize the tectonics of this region by mckenzie 1978 are much improved focal mechanisms of earthquakes constrained by p and sh body wave modelling as well as by first motions these mechanisms show that the faulting in the western part of the aegean region is mostly extensional in nature on normal faults with a nw to wnw strike and with slip vectors directed nnw to nne there is evidence from palaeomagnetism that this western region rotates clockwise relative to stable europe in the central and eastern aegean and in nw turkey distributed right lateral strike slip is more prevalent on faults trending ne to ene and with slip vectors directed ne palaeomagnetic data in this eastern region is more ambiguous but consistent with very small or no rotations in the northern part and possibly anticlockwise rotations relative to europe in the south the strike slip faulting that enters the central aegean from the east appears to end abruptly in the sw against the nw trending normal faults of greece the kinematics of the deformation is controlled by three factors the westward motion of turkey relative to europe the continental collision between nw greece albania and the apulia adriatic platform in the west and the presence of the hellenic subduction zone to the south as the right lateral slip on the north anatolian fault enters the aegean region it splays out becoming distributed on several parallel faults the continental shortening in nw greece and albania does not allow the rotation of the western margin of the region to be rapid enough to accommodate this distributed e w right lateral shear and thus leads to e w shortening in the northern aegean which is compensated by n s extension as the southern aegean margin can move easily over the hellenic subduction zone the dynamics of the system once initiated is self sustaining being driven by the high topography in eastern turkey and by the roll back of the subducted slab beneath the southern aegean the geometry of the deformation resembles the behaviour of a system of broken slats attached to margins that rotate in spite of its extreme simplicity a simple model of such broken slats is able to reproduce quantitatively most of the features of the instantaneous velocity field in the aegean region including the slip vectors and nature of the faulting in the eastern and western parts the senses and approximate rates of rotation the overall extensional velocity across the aegean and the distribution of strain rates as seen in the seismicity and topography or bathymetry and using geodetic measurements as part of this study we re examined the relation between the surface faulting and the focal parameters determined seismologically for the three large 1981 gulf of corinth earthquakes and reassessed the evidence for associating particular earthquakes in the sequence with observed surface faulting an important result is that in one of the events there is a resolvable discrepancy between the slip vector measured at the surface and that determined from the seismic body waves

late cenozoic extension in northeastern greece strymon valley detachment system and rhodope metamorphic core complex the strymon valley detachment system accommodated at least 25 km of extension at the northern margin of the aegean extensional province from middle miocene through early pliocene time the primary detachment surface is exposed as a gently southwest dipping low angle normal fault similar to those widely known in core complex settings of the u s basin and range province for more than 150 km along strike from the aegean sea coast in northeastern greece northward into the struma valley of southern bulgaria hanging wall rocks in the strymon valley detachment system moved in a s53 w direction relative to the footwall resulting ultimately in the tectonic unroofing of the rhodope metamorphic core complex several segments of the strymon valley detachment have previously been interpreted as thrust faults formed during a miocene compressional event our results negate the principal evidence for this event and imply instead that extensional deformation has characterized the northern aegean region since at least middle miocene time displacement ceased on the strymon valley detachment with the late pliocene development of the strymon and drama basins we propose that those basins together with the other principal basins of the northern aegean region are subsiding above an active northeast dipping extensional detachment zone that forms a unified kinematic system with the western offshore continuation of the dextral north anatolian strike slip fault the north aegean trough if this hypothesis is correct then the north aegean trough the western strands of the north anatolian fault and the principal modern depocenters of the northern aegean region may all have originated no earlier than late pliocene time

the tertiary geodynamical evolution of the aegean arc a paleomagnetic reconstruction abstract the paleomagnetic results obtained in the last 5 6 years from tertiary formations in the aegean domain indicate that the lower miocene arc was almost rectilinear with an e w trend and that its curvature has been acquired tectonically in two major phases during the middle miocene a first phase of deformation is characterized by rotations occurring at the two terminations of the arc clockwise in the west epirus anticlockwise in the east southeastern anatolia a second phase of rotation occurring in the last 5 ma about a pole situated in the southern adriatic sea has affected only the northwestern part the data also indicate that the antalya basin has not been involved in the geodynamical evolution of the arc so that the bey daglari represent its easternmost unit a more complex rotational pattern is observed in the internal zones the large rotations measured in evia 48 and skyros 26 probably occurred in the last 5 ma and result from rotation of fault bounded blocks in a shear zone connecting the north aegean trough to the external arc in the izmir region in the karaburun peninsula of western anatolia and in the island of lesbos significant counterclockwise clockwise or null rotations of coherent blocks have taken place during the neotectonic extensional regime furthermore the values of the inclination obtained from both sedimentary and volcanic oligo miocene formations are systematically shallower than expected on the basis of a geocentered dipole field this suggests that the entire studied area has undergone a northward drift of over 1000 km since the middle miocene

the two stage aegean extension from localized to distributed a result of slab rollback acceleration back arc extension in the aegean which was driven by slab rollback since 45 ma is described here for the first time in two stages from middle eocene to middle miocene deformation was localized leading to i the exhumation of high pressure metamorphic rocks to crustal depths ii the exhumation of high temperature metamorphic rocks in core complexes and iii the deposition of sedimentary basins since middle miocene extension distributed over the whole aegean domain controlled the deposition of onshore and offshore neogene sedimentary basins we reconstructed this two stage evolution in 3d and four steps at aegean scale by using available ages of metamorphic and sedimentary processes geometry and kinematics of ductile deformation paleomagnetic data and available tomographic models the restoration model shows that the rate of trench retreat was around 0 6 cm year during the first 30 my and then accelerated up to 3 2 cm year during the last 15 my the sharp transition observed in the mode of ex

tertiary extension of continental crust and uplift of psiloritis metamorphic core complex in the central part of the hellenic arc crete greece kinematic analysis of the deformation in central crete suggests that the structural evolution and exhumation of the high pressure low temperature hp lt rocks outcropping at the mount psiloritis metamorphic core complex are associated with a regional miocene north south extension and thinning of the continental crust this tectonic regime developed under bulk coaxial strain conditions with ductile deformation in the lower and brittle deformation in the upper crust and followed on the decompressional path a north south compression associated with a hp lt metamorphism in the lower crust this compressional event took place during oligocene early miocene and led to overthickening of the accretionary wedge in the hellenic arc an east west directed compression accompanied in the final stages the miocene north south extension of the continental crust

apatite fission track thermochronology of the western pontides nw turkey the results of apatite fission track analyses of the western pontides of nw turkey point to three discrete episodes of cenozoic exhumation correlatable with major supraregional tectonic events 1 paleocene early eocene exhumation reflected the closure of theocean 2 late eocene earliest oligocene exhumation was the result of renewed tectonic activity along thesuture 3 late oligocene early miocene exhumation recorded the onset of northern aegean extension samples collected north and south of the tectonic contact between the two terranes forming the western pontides i e and sakarya terranes record the same cooling events suggesting that such terranes were amalgamated in pre cenozoic times

structural and geochronological evidence for paleogene thrusting in the western rhodopes sw bulgaria elements for a new tectonic model of the rhodope metamorphic province 1 the rhodope metamorphic province in the area around the mesta graben sw bulgaria exposes a structurally lower complex the pangaion pirin complex of variscan continental crust and its cover mostly orthogneiss and marble and a higher complex the rhodope terrane of mixed oceanic and continental origin with metamorphosed jurassic arc magmatites the boundary between the two is the top to the southwest nestos shear zone the regional top to the southwest shearing of the two basement complexes is related to the emplacement of the rhodope terrane over the pangaion pirin complex along this shear zone syntectonic and posttectonic alpine intrusions within the basement can provide age limits for the thrusting zircons from the posttectonic teshovo south pirin granitoid pluton in the pangaion pirin complex yielded crystallization ages of 32 0 2 ma la sf icp ms u pb method zircons from two syntectonic granite plutons in the rhodope terrane dolno dryanovo and spanchevo have circa 143 to 145 ma old inherited magmatic cores and circa 55 to 56 ma old magmatic rims these ages especially the presence of the upper jurassic lower cretaceous cores in the plutons from the rhodope terrane and the structural relations indicate that the southwestward thrusting of the rhodope terrane over the pangaion pirin complex took place in the paleogene a model is proposed in which the pangaion pirin complex represents the margin of apulia and the structure of the rhodopes is explained by a switch of subduction polarity from sw dipping in the jurassic and early cretaceous to ne dipping in the late cretaceous and paleogene

the oligocene xanthi pluton northern greece a granodiorite emplaced during regional extension the xanthi pluton is one of a series of oligocene subduction related granodiorites in northern greece its emplacement was controlled by major faults it is located on the ene trending kavala komotini fault zone which probably originated as a strike slip fault geophysical data show that the pluton is laccolith shaped extending many kilometres south of the fault andesitic dykes several million years older than the pluton indicate a ne sw directed extensional stress field mineral lineations plunging to the sw reflect continued extension during cooling of the pluton subsequent jointing and dykes of aplite and lamprophyre reflect continued extension although this could result from extensional pull apart at a bend during dextral strike slip motion on the kavala komotini fault there is no evidence for subsequent strike slip deformation furthermore two similar laccolithic plutons are unrelated to the kavala komotini fault and the regional extent of thick oligocene sediments suggests an extensional environment during the extension that created a ramp space along the listric fault bounding the xanthi basin into which the granite was intruded the kavala komotini fault acted as a transfer fault reactivation of early joints occurred during late oligocene early miocene compression faults within the pluton parallel to the kavala komotini fault accompanied extension during neogene basin formation emplacement of subduction related magma into ramp space developed along listric faults to produce laccolith like plutons may be a common feature of back arc extension

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

eocene stratigraphic evolution of the thrace basin turkey abstract this paper explains the primary basin evolution processes of the thrace basin which started opening during early middle eocene stratigraphic and tectonic models for different parts of the basin have been constructed and basin scale stratigraphic correlations were established by using outcrop well and seismic data initial deposits of eocene in the thrace basin show irregular depositional patterns associated with various lithofacies deposited under the control of various tectonostratigraphic settings first a compressional regime started after the collision of the sakarya continent with the rhodope pontide fragment in late cretaceous paleocene enabled initiation of transtensional stress which was responsible for the creation of necessary accommodation space for deposition of the initial thrace sediments in the northern and eastern part of the thrace basin the lower middle eocene hamitabat formation was deposited in this kind of transtensional setting and can be divided into various lithostratigraphic units an unconformity identified within hamitabat formation from seismic and well data divides it to two major units in early eocene the thrace basin was deepening eastwards and deposition was initiated between finger shaped paleo highs aligned in an e w direction thus synchronous erosional and depositional events in different parts of the basin formed various facies associated with a variety of depositional environments during the same time interval a regional unconformity at the base of lower eocene between karaagac and hamitabat formations can be correlated from south to north moreover the unconformity between lower middle eocene deposits and the middle eocene limestones of southern thrace is correlative with the unconformity between the hamitabat formation and overlying upper eocene limestones at northern regions this unconformity has a correlative conformity within the gazikoy or kesan formations in central thrace where continuous deposition took place during eocene without interruption

multiple generations of extensional detachments in the rhodope mountains northern greece evidence of episodic exhumation of high pressure rocks abstract an integrated structural and petrological study shows that exhumation of high rocks of the rhodope occurred in several pulses the structurally uppermost kimi complex recording an early cretaceous high p metamorphism was exhumed between about 65 and 42 ma the sidironero kardamos and kechros complexes that record early tertiary high metamorphism at least 19 kbar at 700 c were exhumed at 42 30 ma exhumation occurred with isothermal decompression strain episodes depict thrusting of medium high grade above lower grade high p rocks syn thrusting extension and post thrusting extension polyphase extension created several generations of detachment zones which in sum excise about 20 km of material within the crustal profile this reduction in crustal thickness is consistent with a reduction of the present crustal thickness from more than 40 km to less than 30 km in the eastern rhodope we mapped the post thrusting xanthi low angle detachment system over 100km from its break up zone above the sidironero complex central rhodope into the eastern rhodope this detachment shows an overall ese dip with a ramp and flat geometry cutting across the earlier thrust structures the kimi complex is the hanging wall of all synand post thrusting extensional systems on top of the kimi complex marine basins were formed from the lutetian c 48 43 ma through the oligocene during extension successively at c 26 to 8 ma the thasos pangeon metamorphic core complexes were exhumed in these times representing the early stages of aegean back arc extension the strymon and thasos detachment systems caused crustal thinning in the western rhodope renewed heating of the lithosphere associated with magmatism and exhumation of hot middle crust from beneath the sidironero complex occurred we focusoxn the geometry timing and kinematics of extension and contraction structures related to the 42 30 ma interval and how these exhumed high p rocks we interpret high rocks exhumed in this interval as a window of the apulian plate beneath the earlier in the cretaceous accreted kimi complex

separate eocene early oligocene and miocene stages of extension and core complex formation in the western rhodopes mesta basin and pirin mountains bulgaria abstract the rhodope metamorphic province in bulgaria and northern greece has been affected by significant extensional tectonics since the middle to late eocene an important fault system active in the eocene and early oligocene includes the ribnovo fault on the eastern side of the mesta basin in bulgaria and the vertiskos kerdilion fault in greece together with several minor normal fault relicts identified during this study these represent an originally west southwest dipping low angle at least at the end of faulting normal fault with greenschist facies mylonites in the footwall and cataclasites along the fault plane the mesta kerdilion detachment exposed over ca 150 km along strike and about 50 km parallel to the slip direction during the intrusion of several plutons in the pirin mountains at ca 32 ma the footwall of the fault was uplifted to form a large anticline parallel to fault strike and the fault was offset by a system of antithetic northeast dipping normal faults along the northeastern flank of this anticline dobrotino and breznitsa faults the mesta kerdilion detachment was later in the miocene again crosscut and offset by the southwest dipping strimon valley detachment which accommodated important core complex like exhumation to the south strongly diminishing and finally ceasing towards north this rotational activity of the strimon valley detachment represents the onset of the extension that led to opening of the aegean basin the mesta kerdilion detachment can be viewed as a precursor of this but with slightly different kinematics i e not involving significant vertical axis rotation and separated in time from the following events by a phase of relative tectonic quiescence in the late oligocene

disruption of the hellenic arc late miocene extensional detachment faults and steep pliocene quaternary normal faults or what happened at corinth 1 extensional faults exposed in the peloponnesus and mainland greece most of which are described here for the first time record a transition from regional extension of the aegean domain to the modern tectonic system the east peloponnesus detachment system trends north northwest from the southern peloponnesus to 30 km north of the gulf of corinth dips gently northeast and is late miocene early pliocene in age it has a minimum displacement of 25 30 km and appears to be the youngest of the regional scale extensional systems with significant displacement that formed parallel to the hellenic arc the partially coeval east sterea extensional system which extends from the gulf of corinth to the aegean sea contains low angle normal faults that both crosscut and trend parallel to older structures of the hellenic arc late miocene to early pliocene displacement within this zone disrupted the arc parallel structures of the hellenides upper pliocene quaternary normal faults which trend approximately east west and generally dip steeply at the surface continue the disruption of the hellenic arc much of the subsidence within the gulf of corinth appears to be unrelated to the younger faults and is instead related to the motion on the east peloponnesus detachment which crosscuts the modern graben

a fore arc origin for the thrace basin nw turkey hydrocarbon bearing thrace basin occupies much of the european part of turkey the middle eocene to oligocene sequence in the centre of the basin exceeds 9 km in thickness based on the stratigraphy structure and the regional context of this basin we propose that it developed as a fore arc basin between the medial eocene and the oligocene above the northward subducting intra pontide ocean its post miocene history has been dominated mainly by wrench tectonics resulting from the activity of the now deactivated northwestern strand of the present day north anatolian fault zone

oil and gas fields transfer zone relationships thrace basin nw turkey in the thrace basin oil and gas are produced from carbonate and sandstone reservoirs of eocene and oligocene age detailed geological and geophysical studies reveal that earlier and eocene structures were influenced by basement paleotopography resulting from late cretaceous movements between the arabian and anatolian plates while latest miocene structures were generated by splays of the north anatolian fault in the thrace basin the eocene structures which contain the hamitabat gas and devecatagi and k osmancik oil fields trend in a ne sw direction however miocene structures which are gas producers in the karacaoglan and umurca fields are oriented in a nw se direction parallel to the strike of the main faults which accommodate the transfer zones in the thrace basin the transfer zones occur between faults that dip in opposite directions conjugate and in the same directions synthetic the formation of reservoir zones improvement of reservoir characteristics and generation of oil and gas in the oil window zone were influenced by the timing of faulting and appearance of the transfer zones in the thrace basin

evidence from the mesta half graben sw bulgaria for the late eocene beginning of aegean extension in the central balkan peninsula abstract the ene tilted mesta half graben contains a 3 km thick section of priabonian late eocene to oligocene sedimentary and volcanic rocks that rest unconformably on basement metamorphic rocks along its west side basal strata dip 50 60 e and dip at progressively lower angles upward indicating synrotational deposition the southern part of the half graben contains nested volcanic caldera complexes formed during the deposition of the middle part of the sedimentary sequence which have been rotated by about half the total rotation of the sedimentary succession the half graben is bounded on the east by a fault that steepens from more deeply exposed structural levels in the south 8 18 w to shallower exposed structural levels in the north 70 w and together with the rotation of paleogene strata during deposition indicate the mesta half graben is underlain by a listric detachment fault the mesta detachment subhorizontal middle miocene strata that unconformably overlie tilted paleogene strata yield an upper age limit to the extension west and northwest of the mesta half graben are many other nnw trending ne tilted paleogene half grabens which we suggest are part of an important extended area in sw bulgaria and eastern macedonia that lies above one or more west dipping detachment faults and date the beginning of aegean extension in the southern balkan region as at least as old as priabonian the mesta detachment is oblique to the trend of a contemporaneous paleogene magmatic arc in the southern balkans and the origin of the detachment is probably related to gravitationally induced spreading of thickened hot arc crust and hellenic trench roll back

40ar 39ar laserprobe direct dating of discrete deformational events a continuous record of early alpine tectonics in the pelagonian zone nw aegean area greece abstract the pelagonian zone of the hellenides which occurs in the northwestern aegean region of the eastern mediterranean contains remnants of a high pressure metamorphic belt which subsequently underwent localized reworking during low temperature deformational events formation of alpine deformational structures in the ossa massif northern pelagonian zone occurred at metamorphic temperatures which failed to reset most pre alpine 40ar 39ar cooling ages in muscovite porphyroclasts the low metamorphic temperatures at alpine times have preserved the argon isotopic signature in white mica bearing deformational structures which allows direct dating of these structures and refinement of the alpine tectonic history in the region after separation of carefully selected and characterized mica generations application of sensitive 40ar 39ar laserprobe dating has resulted in a continuous record of the early alpine tectonic history of the ossa massif from the early cretaceous well into the eocene the early alpine history of the ossa massif records cooling of basement thrust slices which are mostly hercynian granites and metamorphics below ca 350 c by 100 ma while lower tectonostratigraphic levels of the basement had already cooled below these temperatures at around ca 285 ma blueschist facies mylonite fabrics related to a top to ene direction of tectonic transport yield ages as old as 84 5 3 3 ma exhumation of the blueschist facies sequences was initiated at ca 54 ma and involved tectonic activity along blueschist facies and greenschist facies mylonites zones final wsw ward transport of the metamorphic sequence across the structurally lowest and supposed autochthonous series occurred at around 45 ma and resulted in termination of the ductile deformation history in the studied area this study confines the onset of high pressure metamorphism in the pelagonian zone to an interval between 100 ma and 85 ma and has shown that high pressure metamorphism had terminated by ca 54 ma the recognition of an early to middle alpine cycle lasting over 30 million years and involving crustal shortening high pressure metamorphism exhumation and subsequent crustal shortening is a key contribution to a better understanding of the early alpine tectonic history of the aegean region and eastern mediterranean

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 subduction system high pressure metamorphism exhumation normal faulting and large scale extension the cenozoic history of the retreating hellenic subduction system in the eastern mediterranean involves subduction accretion arc magmatism exhumation normal faulting and large scale continental extension from 60 mya until the recent ages for high pressure metamorphism in the central aegean sea region range from 53 ma in the north the cyclades islands to 25 20 ma in the south crete younging of high pressure metamorphism reflects the southward retreat of the hellenic subduction zone the shape of pressure temperature time paths of high pressure rocks is remarkably similar across all tectonic units suggesting a steady state thermal profile of the subduction system and persistence of deformation and exhumation styles the high pressure metamorphic events were caused by the underthrusting of fragments of continental crust that were superimposed on slab retreat most of the exhumation of high pressure units occurred in extrusion wedges during ongoing lithospheric convergence at 23 19 mya large s

timing of tectonic emplacement of the ophiolites and terrane paleogeography in the hellenides the timing of tectonic emplacement of the ophiolites is analyzed in the four oceanic terranes of the hellenides h2 h4 h6 h8 the criteria for this analysis are based on a the post emplacement sedimentary cover or intrusive rocks b the syn emplacement tectonostratigraphic formations and c the youngest rocks involved in the structure of the autochthon and the allochthon unit in each case the timing becomes younger towards the more external tectonic units of the hellenides with i late eocene oligocene age in the external ophiolite belt of the pindos cyclades oceanic terrane h2 ii late jurassic early cretaceous age in the internal ophiolite belt of the vardar axios oceanic terrane h4 iii post liassic pre late jurassic age in the ophiolites of lesvos circum rhodope oceanic terrane h6 and iv pre late jurassic age in the ophiolites of volvi eastern rhodope terrane h8 an ophiolite obduction model can be applied with the ophiolitic nappes always emplaced on top of pre alpine continental terranes with mesozoic shallow water carbonate platforms the geometry of the continental terranes drifting during the mesozoic within the tethys ocean controls the number and dimensions of the tethyan oceanic basins where a continental terrane dies out the two adjacent oceanic basins merge into one larger basin this seems to be the case of the pelagonian terrane h3 which is terminated north of skopje where the pindos oceanic basin h2 merges with the vardar axios oceanic basin h4

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

constraining the prograde and retrograde p t t path of eocene hp rocks by shrimp dating of different zircon domains inferred rates of heating burial cooling and exhumation for central rhodope northern greece ion microprobe shrimp dating was carried out on different zircon domains from metamorphic rocks of the hp ht terrane of central rhodope northern greece to constrain the timing of prograde and retrograde stages within a single tectono metamorphic cycle a well determined p t t relative path for the metamorphic rocks of this terrane was used as a petrological basis for the geochronological investigations ion microprobe work was assisted by cathodoluminescence cl images of the zircon crystals the geochronological results revealed that hercynian continental crust was subducted during the eocene several stages of the eocene tectono metamorphic cycle including both the prograde and retrograde parts of the p t path above ca 300 c 0 3 gpa were dated using zircons from the following rock types 1 a deformed quartz vein probably formed at ca 300 c 0 3 gpa zircons in this vein precipitated from a hydrothermal fluid they yielded an age of 45 3 0 9 ma which corresponds to the time of a low t prograde stage of metamorphism 2 in kyanite eclogites zircons were entirely reset during eclogite facies metamorphism resetting was very probably enhanced by the presence of fluids derived by h2o liberating reactions close to the p peak they yielded an age of 42 2 0 9 ma 3 orthogneisses surrounding the kyanite eclogites contained zircons with magmatic oscillatory zoned cores which yielded hercynian ages of 294 8 ma age of granitic protolith formation whereas cl bright metamorphic rims yielded like the eclogite zircons ages of 42 0 1 1 ma therefore both the eclogites and orthogneisses are interpreted to have approached maximum depth at around 42 ma 4 in a leucosome of a migmatized orthogneiss oscillatory zoned zircons yielded an age of 40 0 1 0 ma at this time the rocks reached maximum temperatures during early decompression 5 a late pegmatite crosscutting the schistosity of amphibolites contained oscillatory zoned zircons that yielded a crystallization age of 36 1 1 2 ma thus the whole tectono metamorphic cycle above ca 300 c 0 3 gpa lasted from 45 3 0 9 ma to 36 1 1 2 ma that is 9 2 ma with an extreme error value of 2 1 ma based on combined shrimp and petrological data the average rates of heating and burial during subduction above ca 300 c 0 3 gpa are 94 c ma and 15 mm a respectively rates of cooling and exhumation also above 300 c 0 3 gpa are calculated to be 128 c ma and 7 7 mm a the eocene age of metamorphism in central rhodope implies that the terrane of at least central rhodope and the cyclades very probably was part of the same continental crust

a major oligo miocene detachment in southern rhodope controlling north aegean extension plutonic and metamorphic rocks of the southwest part of the rhodope massif in greece correspond to ductile lower crust exhumed and deformed along a major detachment during post thickening extensional tectonics extension started during the oligocene and is responsible for the development of miocene quaternary sedimentary basins both brittle and ductile deformations result from gravity collapse of previously thickened lithosphere as proposed for others large extended terranes this interpretation disagrees with the previous models which attributed tertiary ductile deformation to alpine thrusting and brittle extensional deformation to back arc tectonics above a subduction zone

kinematics of the southern rhodope core complex north greece the southern rhodope core complex is a wide metamorphic dome exhumed in the northern aegean as a result of large scale extension from mid eocene to mid miocene times its roughly triangular shape is bordered on the sw by the jurassic and cretaceous metamorphic units of the serbo macedonian in the chalkidiki peninsula and on the n by the eclogite bearing gneisses of the sideroneron massif the main foliation of metamorphic rocks is flat lying up to 100 km core complex width most rocks display a stretching lineation trending ne sw the kerdylion detachment zone located at the sw controlled the exhumation of the core complex from middle eocene to mid oligocene from late oligocene to mid miocene exhumation is located inside the dome and is accompanied by the emplacement of the synkinematic plutons of vrondou and symvolon since late miocene times extensional basin sediments are deposited on top of the exhumed metamorphic and plutonic rocks and controlled by steep normal faults and flat ramp type structures evidence from thassos island is used to illustrate the sequence of deformation from stacking by thrusting of the metamorphic pile to ductile extension and finally to development of extensional plio pleistocene sedimentary basin paleomagnetic data indicate that the core complex exhumation is controlled by a 30 dextral rotation of the chalkidiki block extensional displacements are restored using a pole of rotation deduced from the curvature of stretching lineation trends at core complex scale it is argued that the rhodope core complex has recorded at least 120 km of extension in the north aegean since the last 40 my

tectonic sedimentary evolution of the western margin of the mesozoic vardar ocean evidence from the pelagonian and almopias zones northern greece

exhumation of high pressure rocks a review of concepts and processes the exhumation of high pressure metamorphic rocks requires either the removal of the overburden that caused the high pressures or the transport of the metamorphic rocks through the overburden exhumation cannot be achieved simply by thrusting or strike slip faulting it may be caused by erosion of shortened and thickened crust but this is unlikely to be the only mechanism for exhuming rocks from depths greater than about 20 km one or more of the following additional mechanisms may be involved 1 corner flow of low viscosity material trapped between the upper and lower plates in a subduction zone can cause upward flow of deeply buried rock and may explain some occurrences of high pressure tectonic blocks in melange this process does not however appear to be adequate to explain the exhumation of regional high pressure terrains 2 buoyancy forces acting directly on metamorphic rock bodies may cause them to rise relative to more dense surroundings this is likely to be the most important mechanism of exhumation of crustal rocks subducted into the mantle but cannot explain the emplacement of coherent tracts of high density metamorphic rock into shallow crustal levels some high pressure blocks emplaced at shallow levels in accretionary terrains may have been entrained in diapiric intrusions of low density mud or serpentinite 3 extension driven by the forces associated with contrasts in surface elevation may explain the exhumation and structural setting of many high pressure terrains extension may occur in the upper part of an accretionary wedge thickened by underplating or it may affect the whole lithosphere in a region of intracontinental convergence if surface elevation has been increased by the removal of a lithospheric root in the second case extension may be accompanied by magmatism and an evolution towards higher temperature during decompression of the metamorphic terrain

2 hydrothermal ore deposits related to post orogenic extensional magmatism and core complex formation the rhodope massif of bulgaria and greece abstract the rhodope massif in southern bulgaria and northern greece hosts a range of pb zn ag cu mo and au ag deposits in high grade metamorphic continental sedimentary and igneous rocks following a protracted thrusting history as part of the alpine himalayan collision major late orogenic extension led to the formation of metamorphic core complexes block faulting sedimentary basin formation acid to basic magmatism and hydrothermal activity within a relatively short period of time during the early tertiary large vein and carbonate replacement pb zn deposits hosted by high grade metamorphic rocks in the central rhodopean dome e g the madan ore field are spatially associated with low angle detachment faults as well as local silicic dyke swarms and or ignimbrites ore formation is essentially synchronous with post extensional dome uplift and magmatism which has a dominant crustal magma component according to pb and sr isotope data intermediate and high sulphidation pb zn ag au deposits and minor porphyry cu mo mineralization in the eastern rhodopes are predominantly hosted by veins in shoshonitic to high k calc alkaline volcanic rocks of closely similar age base metal poor high grade gold deposits of low sulphidation character occurring in continental sedimentary rocks of synextensional basins e g ada tepe show a close spatial and temporal relation to detachment faulting prior and during metamorphic core complex formation their formation predates local magmatism but may involve fluids from deep mantle magmas the change in geochemical signatures of palaeogene magmatic rocks from predominantly silicic types in the central rhodopes to strongly fractionated shoshonitic bulgaria to calc alkaline and high k calc alkaline greece magmas in the eastern rhodopes coincides with the enrichment in cu and au relative to pb and zn of the associated ore deposits this trend also correlates with a decrease in the radiogenic pb and sr isotope components of the magmatic rocks from west to east reflecting a reduced crustal contamination of mantle magmas which in turn correlates with a decreasing crustal thickness that can be observed today hydrogen and oxygen isotopic compositions of the related hydrothermal systems show a concomitant increase of magmatic relative to meteoric fluids from the pb zn ag deposits of the central rhodopes to the magmatic rock hosted polymetallic gold deposits of the eastern rhodopes

neotectonic and seismological data concerning major active faults and the stress regimes of northern greece northern greece is an intracontinental region behind the hellenic subduction zone with widespread seismic activity ranging from low to high with strong destructive earthquakes of mg6 0 in historical to recent times geological and seismological data indicate that recent seismic activity is mainly localized along large inherited fault zones which have transected northern greece since oligocene miocene times the main active fault zones in thrace and eastern and central macedonia strike approximately east west with lengths of 40 120 km fault segments strike wnw ese to ene wsw and range from 10 to 30 km in length in western macedonia the main active fault zones strike ne sw to ene wsw with lengths of 40 60 km and consist of 10 30 km segments the region s strong earthquakes are usually associated with reactivation of these fault segments and are estimated at m 5 6 6 5 focal mechanisms and fault slip data from the fault zones indicate a change in the trend of extension axes from nne ssw in eastern macedonia thrace to nnw sse in western macedonia thus neotectonic and seismological data suggest that variations in fault patterns as determined from the large inherited fault zones transecting northern greece are the major factor governing this change in the trend of maximum extension this interpretation is consistent with the long lived arcuate shape of the hellenic subduction zone of these the best known are the 1978 thessaloniki earthquake of m 6 5 papazachos et al 1979 and the 1995 kozani grevena earthquake pavlides et al 1995 mountrakis et al 1996c 1998 papazachos et al 1998a with the latter occurring in the low seismicity western macedonia region the rupture zones in northern greece need a thorough re examination in the light of recent advances in our understanding of active faulting and the new data provided by the aristotle university seismological network our aim is to identify the large active fault zones in northern greece from their geometric kinematic and seismotectonic features to define controlling stresses and to elucidate the continuity or extent of these zones the main aim is to better understand the active deformation of these areas and to determine whether fault deformation in northern greece is concentrated into relatively narrow bands or zones as one of the major issues in continental mechanics is how fault slips in the upper crust reflect more distributed flow in the lower lithosphere e g mckenzie jackson 1983 molnar gipson 1994 bourne et al 1998 information about active faulting and driving stresses in such areas is very useful brittle deformation within intracontinental regions is usually associated with distributed faulting and seismic activity however within such broad deforming regions some parts although transected by large faults are characterized by relatively less intense seismic activity and slip rates northern greece lies in the inner part of the continental collision region of nw greece and albania close to the intensely north south aegean extended sea this deformation is driven by the hellenic subduction zone and the westward extrusion of anatolia fig 1a in the older greek seismic code some large areas of macedonia e g western macedonia are classified as almost aseismic and other adjacent ones e g central macedonia as highly seismic recent instrumental data obtained from the regional seismological network of the aristotle university of thessaloniki after its installation in 1980 have confirmed the existence of significant seismicity in northern greece fig 1b particularly along narrow rupture zones papazachos et al 2001 furthermore large earthquakes have been reported in historical times papazachos papazachou 2003 and several strong and destructive ones have been recorded instrumentally during the last century 650 d mountrakis et al fig 1 a schematic map showing the position of northern greece in the broader eastern mediterranean geotectonic regime modified from papazachos papazachou 2003 b spatial distribution of instrumentally recorded earthquakes 1911 2004 with magnitudes mg3 0 for the broader study area ctf cephalonia transform fault rtf rhodes transform fault ptf paphos transform fault geology and seismotectonics of northern

multistage exhumation of the menderes massif western anatolia turkey structural analyses along selected transects across the menderes massif and incorporation of existing data have resulted in a synthetic cross section across southwestern turkey the tectonic interpretation has been combined with 40ar 39ar laser probe experiments on two syn kinematic white mica populations which respectively predate and overprint documented early miocene deformational fabrics our results indicate that the regional extension had initiated by eocene oligocene times a 36 2 ma 40ar 39ar age derived from white mica which formed during a regionally observed northward directed tectonic transport suggests that the extension was contemporaneous with the tectonic emplacement of mid crustal continental basement alternatively the age may relate to the regional cooling of the basement sequence and thus postdates the tectonic emplacement in the latter scenario the analysis fails to solve the present ambiguity on the pan african or alpine affinity of the northward directed transport further exhumation of basement rocks is characterized by a dominant displacement along the north dipping gediz detachment at the northern margin of the massif which developed under ductile conditions in the early miocene by partial exploitation of older zones of weakness which originated from an earlier phase of basement emplacement youngest semi ductile activity along the gediz detachment has been recorded as having a 7 1 ma 40ar 39ar age derived from syn kinematic white mica in the top of the detachment following the initiation of the ductile gediz detachment an antithetic semibrittle and south dipping buyuk menderes detachment had developed in the center of the massif which together with the gediz detachment accommodated further doming of the central part of the menderes massif and controlled the architecture of the surrounding supradetachment basins

middle eocene sedimentary and volcanic infilling of an evolving supradetachment basin white lake basin south central british columbia the middle eocene white lake and skaha formations in the white lake basin british columbia record the sedimentary and volcanic infilling of a supradetachment basin that developed during the latter stages of shuswap metamorphic core complex exhumation the 1 1 km thick white lake formation is characterized by volcanogenic sediment gravity flow fluvial and sheetflood facies interbedded with volcanic deposits facies relations suggest white lake strata accumulated on coalesced west sloping alluvial fans that drained an active volcanic center the overlying 0 3 km thick skaha formation records increased tectonism and mass wasting pervasively shattered skaha avalanche slide and sheetflood deposits accumulated on alluvial fans shed from hanging wall and footwall sources exposed along the okanagan valley fault clast compositions of the white lake and skaha formations record alluvial and tectonic stripping that locally eliminated hanging wall blocks mylonite clasts in upper skaha beds imply significant okanagan valley fault footwall uplift during the middle eocene and syntectonic erosion of the shuswap metamorphic core complex the syntectonic sedimentary record preserved within the white lake basin elucidates the relations and timing between core complex exhumation and extensional tectonism in this region the white lake and skaha formations are the apparent age equivalent of the klondike mountain formation of northern washington usa white lake basin strata however are more complexly interstratified post depositionally disrupted and contain a more complete record of core complex unroofing variations in the spatial distributions and textural and compositional character of middle eocene strata in this area underscore the need to exercise care when developing regional scale sedimentary tectonic volcanic models