timing kinematics and cause of aegean extension a scenario based on a comparison with simple analogue experiments abstract since the early 1970s most geodynamic models proposed for the eastern mediterranean consider that the initiation of extension in the aegean during the late middle miocene or later was a direct consequence of the westward extrusion of anatolia away from the arabia eurasia collision front in the late 1990s a few models have taken into account the increasing evidence for an earlier initiation of aegean extension arising mostly from the analysis of deformation within the various alpine metamorphic complexes of the area based largely on our own investigations we first present a review of the data that reliably constrain the minimum age for the initiation of extension in these complexes it shows that regional scale extension with a pattern of stretching orientations similar to that of the pliocene pleistocene was already strongly active in the aegean before the onset of arabian indentation into eurasia lower miocene vs middle or upper miocene this implies that the initiation of aegean extension did not result from the lateral extrusion of anatolia instead extension may have started owing to a process of gravity spreading of the continental lithosphere that had previously been thickened during alpine collision the main arguments favouring this interpretation are presented and a preliminary scenario is proposed for the neogene evolution of the eastern mediterranean in which lateral extrusion of anatolia occurred lately during southward spreading of the aegean lithosphere in order to test this hypothesis further physical experiments simulating the horizontal spreading of a continental lithosphere toward a free boundary have been carried out the analysis of various elements of the deformation field displacements strain rotations fault pattern and kinematics both in the experiments and in the aegean domain reveals an excellent agreement between the two not only do early stages of aegean extension appear to fit the gravity spreading hypothesis but so does the recent to present internal deformation of the aegean transverse e w active shortening observed in the northern aegean is commonly taken as one of the most striking pieces of evidence that aegean extension results from the lateral extrusion of anatolia the experiments indicate that such transverse shortening may equally develop as a result of pure gravity spreading associated with a pattern of faults and rotations that compares well with that of the northern aegean pure dextral shearing along some strands of the north aegean trough fault system and the related development of an asymmetric pattern of faults in the northern aegean are eventually the only features that evidently arise from the extrusion of anatolia since less than 3 ma finally we argue that during the early stages of aegean extension since at least 21 ma and until ca 11 ma the distribution of extensional strain on a regional scale has been controlled by the distribution of earlier thickening post thickening thermal weakening through partial melting of deep levels of the crust probably accounts for the localization of extensional strain within the areas of thick crust restoring the aegean in its most likely configuration at the onset of bulk crustal extension suggests that 1 the extensional strain rate remained roughly constant or has eventually decreased since the onset of aegean extension and 2 the amounts of extension before and after 16 ma have been roughly equal

upper cretaceous exhumation of the western rhodope metamorphic province chalkidiki peninsula northern greece the vertiskos unit of northern greece is an elongated basement belt with a complex poly metamorphic history it extends from greece chalkidiki peninsula to the south up to serbia in the north and arguably represents the westernmost part of the rhodope metamorphic province northern greece to southern bulgaria the vertiskos unit experienced a medium pressure lower amphibolite facies metamorphic overprint during the alpine orogeny the available medium temperature geochronology implies that it remained at temperature of approximately 300 c or slightly higher during lower cretaceous in order to constrain its post lower cretaceous thermal history until near surface exposure we applied apatite fission track analysis the central ages obtained range from 68 5 3 8 to 46 6 3 6 ma uppermost cretaceous to middle eocene and mean track lengths between 13 and 13 5 m we applied two inverse thermal modeling approaches using either each sample independently high degree of freedomin the thermal history better data fit or all samples together interpreting them as a vertical profile simpler thermal history worse data fit irrespective of the modeling approach we conclude that the bulk thermal history of the vertiskos unit crosses the high temperature limit of the apatite partial annealing zone by the uppermost cretaceous and reaches near surface conditions as early as lower middle eocene these results contrast with the thermal history of the other domains of the rhodope metamorphic province further east namely the southern rhodope core complex and the northern rhodope complex and establish the vertiskos basement complex as the oldest exhumed coherent basement fragment of the rhodope metamorphic province and greece

dextral rotations and tectonomagmatic evolution of the southern rhodope and adjacent regions greece abstract palaeomagnetic measurements deduced from eocene oligocene miocene and pliocene formations exposed in the greek rhodope and surrounding areas reveal significant clockwise rotations displaying an apparent systematic increase in magnitude from thrace westwards and a decrease northwards the pelagonian zone in the west has suffered no rotation at least since the late miocene a transition from rotated to unrotated regions seems to exist close to the western boundary of the vardar zone no rotations are apparent earlier than the mid oligocene parts of the rhodope may have been rotated clockwise by 12 during the late oligocene additional clockwise rotations occurred after the early miocene it is proposed that at least the post early miocene rotations were the result of plate tectonic motions in the north aegean area initiated by middle miocene times and continuing to the present day southward stretching and bending of the ductile part of the lithosphere was accomplished at brittle upper crustal levels by the detachment translation and rotation of the upper plate of the rhodope core complex the serbomacedonian element possibly followed by further fragmentation and rotation of individual blocks

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

tectonostratigraphic models of the alpine terranes and subduction history of the hellenides abstract the tectonostratigraphy of the hellenic terranes is related to their paleogeodynamic and paleogeographic evolution which comprises three major stages i continental rifting in the northern margin of gondwana characterised by volcanosedimentary complexes of late paleozoic triassic ii continental drifting and contemporaneous oceanic opening of tethyan basins in between the continental terranes during triassic paleogene with shallow water carbonate platforms on the continental terranes and ophiolite suites interlayered with pelagic sediments within the tethyan basins iii accretion of the tectonostratigraphic terranes with docking along the active european margin characterised by flysch melange sedimentation along the trenches from early jurassic to neogene two tectonostratigraphic models can be distinguished one for the continental terranes carbonate platforms and another for the oceanic basins the duration of each geodynamic stage for each terrane is obtained from the chronology of the tectonostratigraphic facies change the general trend is younger ages observed in the southern terranes and older ages towards the northern terranes the two alternative tectonostratigraphic models are applied in the two groups of terranes and the chronology of the geodynamic paleogeographic stages is estimated the hellenic subducted slab as shown in the seismic tomographic images is correlated to the terrane paleogeography using the estimated widths and the average subduction rates the upper 1700 km of the slab correspond to the three southern more external terranes whereas the remainingpart of the slab may represent the other more internal terranes a palinspastic model of the hellenides is presented taking into account the chronology of each stage for every terrane obduction of ophiolites over the southern platforms is observed in all four oceanic basins blueschist exhumation formation of core complexes and tectonic windows through extensional detachments occur after micro collision of continental terranes platforms and their isostatic uplift within the upper plate after their detachment from the subducting slab

low temperature constraints on the cenozoic thermal evolution of the southern rhodope core complex northern greece the south rhodope core complex srcc of northern greece is probably the most studied metamorphic core complex of the rhodope massif and yet its geological evolution has not yet been fully unravelled especially the later stages of its thermotectonic evolution we applied the fission track method on apatite and zircon and the u th sm he method on apatite in order to reconstruct the low temperature thermal history the main detachments responsible for the unroofing of the core complex are the kerdilion and the strymon valley detachments the kerdilion detachment initiated the exhumation of the srcc at the latest at 42 ma and controlled it until about 24 ma between 24 and 12 ma the strymon valley detachment accommodated the exhumation since 12 ma brittle normal faults some of them cutting the strymon valley detachment were responsible for the final cooling of the basement rocks in the studied area and the formation of syn tectonic sedimentary basins activity along these brittle normal faults lasted until 6 ma or probably even until today as indicated by recent seismic activity in the area

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

estimated ground motion from the 1994 northridge california earthquake at the site of the interstate 10 and la cienega boulevard bridge collapse west los angeles california we have estimated ground motions at the site of a bridge collapse during the 1994 northridge california earthquake the estimated motions are based on correcting motions recorded during the mainshock 2 3 km from the collapse site for the relative site response of the two sites shear wave slownesses and damping based on analysis of borehole measurements at the two sites were used in the site response analysis we estimate that the motions at the collapse site were probably larger by factors ranging from 1 2 to 1 6 than at the site at which the ground motion was recorded for periods less than about 1 sec

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

static fatigue of granite at 200 c cylinders of barre and westerly granites have been compressed to failure in static fatigue tests under dry and wet conditions at 1 kb confining pressure and temperatures of 24 sup 0 and 200 sup 0 c the effect of increasing temperature and water content is as expected to weaken the rocks appreciably and to reduce the time to failure at constant stress by about two orders of magnitude the activation energy estimated for dry barre granite deformed in temperature range 24 sup 0 to 200 sup 0 c is 10 2 kcal mol which seems reasonable and is consistent with other work at higher temperatures extrapolation of the static fatique equations obtained for specimens deformed at 200 sup 0 c both wet and dry to 10 sup 8 years yields maximum stress differences near 3 kb while such extrapolations may be reasonable for intact material over time spans of interest to national concerns the stresses obtained seem unreasonably high for tectonic deformations the discrepancy probably results from the very short durations of the tests which do not permit effective operation at these low temperatures of the several thermally activated weakening effects of h sub 2 o on silicates

tectonometamorphic evolution of the rhodope orogen 1 this study combines new data on tectonostratigraphy macrostructures and microstructures petrology and geochronology to propose a comprehensive model for the tectonometamorphic evolution of the rhodope orogen from the jurassic to the early paleogene rocks from two study areas in the central and eastern greek rhodope represent a continental suture zone rhodope suture zone with the included material most likely forming an extensional allochthon south of the european continent during permo triassic times that was subsequently subducted beneath europe in the early jurassic 180 ma on the basis of comparable metamorphic ages and coherent structures but differences in metamorphic conditions and lithologies the rocks of the rhodope suture zone are subdivided into an upper and a lower part the prograde history is linked with subduction related structures in the lower part uniaxial stretching deformation stage d1 in metapelites the earliest stage of metamorphism recorded at circa 180 ma occurred at least under ultrahigh pressure metamorphic conditions the rocks of the upper part experienced isothermal decompression with partial anatexis exhumation paths of both parts differ in temperature because of the relative tectonic position within the exhuming wedge exhumation was forced by the nestos shear zone that controlled the early phase of normal displacement by sw shearing at the base lower part and ne shearing on top upper part from the late jurassic to the late cretaceous deformation stage d2 an intervening stage of mineral recrystallization and thermal reequilibration in the upper part was followed by a common exhumation history of both parts at pressures lower than about 12 kbar 35 40 km depth during this stage exhumation was controlled by southwest directed shearing and folding deformation stage d3 slab retreat to the south led to subsequent extension deformation stage d4 and final exhumation coeval with the formation of basement domes thus making the rhodope a classic core complex juxtaposed with former structurally higher units

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

exhumation of high pressure rocks driven by slab rollback rocks metamorphosed under high pressure hp and ultra high pressure uhp conditions in subduction zones come back to the surface relatively soon after their burial and at rates comparable to plate boundary velocities in the mediterranean realm their occurrence in several belts related to a single subduction event shows that the burial exhumation cycle is a recurrent transient process using the calabria apennine and aegean belts as examples we show that the exhumation of hp rocks is associated in time and space with the subduction of small continental lithosphere blocks that triggers slab rollback creating the necessary space for the exhumation of the buoyant continental crust that was deeply buried just before the buoyancy force of the subducted crust increases until this crust detaches from the downgoing slab it then exhumes at a rate that depends directly on the velocity of trench retreat to become part of the overriding plate heated from below by the asthenosphere that flows into the opening mantle wedge the exhumed crust weakens and undergoes core complex type extension responsible for a second stage of exhumation at a lower rate the full sequence of events that characterizes this model crust mantle delamination slab rollback and trench retreat hp rock exhumation asthenosphere heating and core complex formation arises entirely from the initial condition imposed by the subduction of a small continental block no specific condition is required regarding the rheology and erosion rate of hp rocks the burial exhumation cycle is transient and can recur every time a small continental block is subducted

topographic slope as a proxy for seismic site conditions and amplification we describe a technique to derive first order site condition maps directly from topographic data for calibration we use global 30 arc sec topographic data and v s 30 measurements here v s 30 refers to the average shear velocity down to 30 m aggregated from several studies in the u s as well as in taiwan italy and australia v s 30 values are correlated against topographic slope to develop two sets of parameters for deriving v s 30 one for active tectonic regions where topographic relief is high and one for stable shields where topography is more subdued by taking the gradient of the topography and choosing ranges of slope that maximize the correlation with shallow shear velocity observations we can recover to first order many of the spatially varying features of sitecondition maps developed for california our site condition map for the low relief mississippi embayment also predicts the bulk of the v s 30 observations in that region despite rather low slope ranges we find that maps derived from the slope of the topography is often well correlated with other independently derived regional scale site condition maps but the latter maps vary in quality and continuity and subsequently also in their ability to match observed v s 30 measurements contained therein alternatively the slope based method provides a simple approach to uniform site condition mapping

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

time dependent cracking and brittle creep in crustal rocks a review abstract rock fracture under upper crustal conditions is driven not only by applied stresses but also by time dependent chemically activated subcritical cracking processes these subcritical processes are of great importance for the understanding of the mechanical behaviour of rocks over geological timescales a macroscopic manifestation of time dependency in the brittle field is the observation that rocks can deform and fail at constant applied stresses a phenomenon known as brittle creep here we review the available experimental evidence for brittle creep in crustal rocks and the various models developed to explain the observations laboratory experiments have shown that brittle creep occurs in all major rock types and that creep strain rates are extremely sensitive to the environmental conditions differential stress confining pressure temperature and pore fluid composition even small changes in any of these parameters produce order of magnitude changes in creep strain rates and times to failure three main classes of brittle creep model have been proposed to explain these observations phenomenological statistical and micromechanical statistical and micromechanical models explain qualitatively how the increasing influence of microcrack interactions and or the increasing accumulated damage produces the observed evolution of macroscopic deformation during brittle creep however no current model can predict quantitatively all of the observed features of brittle creep experimental data are limited by the timescale over which experiments are realistically feasible clearly an extension of the range of available laboratory data to lower strain rates and the development of new modelling approaches are needed to further improve our current understanding of time dependent brittle deformation in rocks

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

spatial correlation of spectral acceleration in european data abstract quantification of regional seismic risk is based on spatially correlated random fields and requires modeling of the joint distribution of ground motion intensity measures at all sites of interest in particular when a portfolio of buildings or a transportation distribution network lifeline is of concern correlation models for elastic spectral acceleration sa may also be required in order to estimate the expected loss in case of seismic events the presented study focuses on semi empirical estimation of spatial correlation as a function of intersite separation distance in fact this paper complements and is based on preceding work of the authors referring to spatial correlation of peak ground acceleration and velocity esposito and iervolino 2011 the evaluation of correlation for ground motion residuals was performed on data from multiple earthquakes considering different ground motion prediction equations fitted to the same records correlation analyses carried out through geostatistical tools considered two datasets the italian accelerometric archive and the european strong motion database results appear generally consistent with previous research on the same topic finally simple relationships providing the correlation range of intraevent residuals of sa as a function of structural period were derived for each dataset the developed models are useful for earthquake engineering applications where spatial correlation of peak ground motion is required

the carpatho balkanides and adjacent area a sector of the tethyan eurasian metallogenic belt the tethyan eurasian metallogenic belt temb was formed during mesozoic and post mesozoic times in the area of the former tethyan ocean on the southern margin of eurasia with the afro arabian and indian plates to the south it extends from western mediterranean via the alps and southeastern europe through the lesser caucasus the hindu kush and the tibet plateau to burma and sw indonesia linking with the west pacific metallogenic belt the carpatho balkan region is one of the sectors of the temb characterized by some specific features the emplacement of ore deposits is related to a definite time interval and to specific tectonic settings such as

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

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

an updated probabilistic seismic hazard assessment for romania and comparison with the approach and outcomes of the share project the probabilistic seismic hazard analysis for romania is revisited within the framework of the bigsees national research project http infp infp ro bigsees default htm financed by the romanian ministry of education and scientific research in the period 2012 2016 the scope of this project is to provide a refined description of the seismic action for romanian sites according to the requirements of eurocode 8 to this aim the seismicity of all the sources influencing the romanian territory is updated based on new data acquired in recent years the ground motion models used in the analysis as well as their corresponding weights are selected based on the results from several recent papers also published within the framework of the bigsees project the seismic hazard analysis for romania performed in this study are based on the traditional cornell mcguire approach finally the results are discussed and compared with the values obtained in the recently completed share research project the bigsees and share results are not directly comparable since the considered soil conditions are different actual soil classes for bigsees and rock for share nevertheless the analyses of the seismic hazard results for 200 sites in romania reveal considerable differences between the seismic hazard levels obtained in the present study and the share results and point out the need for further analyses and thorough discussions related to the two seismic hazard models especially in the light of a possible future harmonized hazard map for europe

geology and geochronology of the arnea sithonia and ouranopolis intrusions chalkidiki peninsula northern greece abstract the chalkidiki peninsula comprises the greek geotectonic units of the vardar axios zone and the serbo macedonian massif several granitic bodies of various ages intrude this area and many of them are of unknown or disputed age the ages of the arnea sithonia and ouranopolis granitoids are investigated using 40 ar 39 ar stepheated mineral and rb sr whole rock analyses the arnea granite has experienced intense but variable deformation recrystallization and retrogression in general it lacks easily datable minerals because of it s highly evolved silica rich composition however coarse grained phlogopitic mica separated from a minor less evolved porphyritic part of the intrusion yields an excellent 40 ar 39 ar plateau age of 136 1 ma rb sr whole rock samples give a regression line of age 155 11ma and an initial 87 sr 86 sr ratio of 0 7174 0 0017 mswd 280 the scatter may reflect the widespread recrystallization and deformation of the arnea granite the arnea granite is at least late jurassic in age and has undergone regional greenschist metamorphism during the early cretaceous biotite from the sithonia granitoid yields a plateau age of 43 0 6 ma muscovites from crosscutting pegmatites within the granitoid give slightly saddle shaped age spectra with minimum ages of 49 ma and 50 ma suggesting argon 40 excess biotite and muscovite from the ouranopolis granitoid yield plateau ages of 44 1 1 ma and 47 0 7 ma respectively it is suggested that this granitoid is coeval and cogenetic with the sithonia granitoid both intrusions are eocene in age rb sr whole rock samples from the sithonia and ouranopolis granitoids failed to provide any isochrons this is interpreted to be due to inhomogeneities in these young intrusions the age data strongly suggest that the sithonia and ouranopolis granitoids are unrelated to the arnea granite coupled with geochemical and petrographic data these results clarify the relationships between some of the granitic intrusions and have important regional implications

effects of temperature and stress on the time dependent behavior of beishan granite the time dependent behavior of the beishan granite at different t and stress level is studied

microstructural based time dependent failure mechanism and its relation to geological background abstract the time dependent hydro mechanical behavior of rocks is important in assessing the long term stability of deep underground excavation sites meant for long term storage of radioactive waste while evaluating the manner in which damage growth progresses at an excavation site it is important to represent the failure criteria and microcrack evolution from the viewpoint of factors pertaining to microcrack geometry such as the crack density we performed creep tests on inada granite samples to examine the effects of water confining pressure and weathering on time dependent failure the crack density of the samples which was damaged at three characteristic stages of creep behavior i e primary secondary and tertiary creep was measured by means of a longitudinal wave velocity test the microcrack evolution and failure criteria are discussed on the basis of the crack tensor determined in the test the following conclusions were reached from the test results 1 the onset of tertiary creep corresponds to the peak stress under static loading conditions and the tertiary creep stage corresponds to the post failure region 2 at the onset of tertiary creep the crack density can be the failure criterion for time dependent failure and crack density can be estimated using the longitudinal wave velocity 3 the time to failure for weathered granitic rock is approximately ten times faster than that for intact granitic rock 4 the ratio of the mica group mineral in the granite may affect the time to failure a fact that offers insight into the time dependent stability of a rock mass on the field scale

tertiary granitoids of rhodope northern greece magmatism related to extensional collapse of the hellenic orogen abstract many granites that occur in orogenic belts such as the himalaya the hercynides or caledonides are thought to result from anatexis of the lower parts of over thickened thrust stacked crustal units just preceding termination of the orogenic cycle numerous tertiary granitoids occur in the rhodope zone of northern greece and adjacent regions of bulgaria a belt regarded as an eastern extension of the alpine system these granites could also be regarded as syn or late tectonic crustal melts in that some have been emplaced as sheet like bodies along major alpine thrust planes and show a strong marginal foliation parallel to the pervasive alpine compressional fabrics in detail however the geochemistry of the granitoids their timing and relationships with country rocks suggest they have been emplaced in an extensional regime that is related to the collapse of the hellenic orogen and more particularly to the crustal thinning that the aegean region has suffered since the mid tertiary rather than being products of crustal thickening it is suggested that their petrogenesis is related to the elevation of thermal gradients during the extensional phase which initiated thermal breakdown of hydrous minerals in the lithosphere and lower crust that had existed metastably during compression and the subduction of cool ocean lithosphere beneath the region in the late mesozoic early tertiary

spatial correlation of ground motions from vrancea romania intermediate depth earthquakes the evaluation of the spatial correlation of ground motions is the first step toward an assessment of the seismic risk on a regional scale this short study focuses on the evaluation of the spatial correlation of ground motions recorded during intermediate depth earthquakes produced in the vrancea subcrustal seismic source in romania for eight spectral periods in the 0 0 3 0 s range a recently developed ground motion model is used as reference and the database consists of around 300 ground motions recorded during eight intermediate depth vrancea earthquakes an exponential model is fitted on the experimental semivariograms and the resulting correlation ranges are compared with the values obtained in previous studies

45 m y of aegean crust and mantle flow driven by trench retreat the available seismic anisotropy data in the aegean shallow mantle and their relationship with crustal deformation are used for deciphering the lithosphere scale flow pattern driven by rollback of the hellenic subduction slab in the north and central aegean the directions of mantle seismic anisotropy trend parallel to stretching lineations in core complexes of the overlying crust suggesting that crust and mantle have undergone the same direction of flow at the scale of the entire aegean crustal extension is controlled by dextral rotation around a pole located at scutary pec albania that is related to the hellenic trench retreat the intensity of mantle anisotropy increases as a function of distance from the pole and of amount of rotation surface geology reveals that this rotating flow pattern resulted in strains accumulated since 45 ma a slab tear model is suggested to integrate the observed variations of geological events in time and space to subduction dynamics

characterization of damage evolution in granite under compressive stress condition and its effect on permeability abstract with the aid of 3d acoustic emission ae monitoring system the cracking process of granite under compressive stress condition and its effect on the hydro mechanical properties is experimentally studied the granite is taken from beishan area a preferable region for high level radioactive waste hlw disposal in china the experiment results suggest that the rock failure and degradation of mechanical properties are essentially related to the propagation and coalescence of induced cracks using an anisotropic damage tensor proposed by shao et al the damage evolution during the whole loading process is studied according to the experimental data it is revealed that the damage evolution is mainly initiated with the appearance of nonlinear mechanical behaviour and accelerated close to the failure point and in post peak region the estimated damage variable in lateral direction is found be globally higher than the value in vertical direction the recorded ae events indicate that cracking process of granite could be accelerated due to the existence of hydraulic pressure as a result much lower compressive strength is obtained under same effective confining pressure in hydro mechanical coupling tests a similar tendency of damage and permeability is noticed and the permeability variation in granite is found to be negligible before the coalescence of microcracks finally an empirical relation is proposed to describe the influence of damage evolution and confining pressure on permeability variation

probabilistic characterization of spatially correlated response spectra for earthquakes in japan seismic hazard and risk assessments of spatially distributed infrastructural systems require seismic demand models that capture random but correlated simultaneous seismic effects at multiple sites this study characterizes spatially correlated ground motion parameters probabilistically using comprehensive databases of the k net and kik net strong motion networks in japan by developing a ground motion prediction equation and then investigating the correlation structure of regression residuals from the prediction equation analysis results indicate that 1 interevent residuals of ground motion parameters at different vibration periods are more strongly correlated than intraevent and total residuals with zero separation distance and 2 intraevent spatial correlation coefficients can be described as a simple exponential decay function that is independent of the way the event based intraevent standard deviation is calculated of the earthquake type and of the vibration period the developed overall correlation model of spatially correlated ground motion parameters may be used for seismic hazard and risk assessments in a subduction environment

triassic rift related meta granites in the internal hellenides greece the serbo macedonian massif is a basement complex in the internal hellenides of northern greece situated between the vardar zone to the west and the rhodope massif to the east the serbo macedonian massif comprises several distinct basement units interpreted as terranes the largest of which is the gondwana derived vertiskos terrane in the northwestern and central parts of the massif a series of leucocratic meta granites intrude the silurian orthogneiss basement of the vertiskos terrane no similar granites are found in any of the other units of the internal hellenides the meta granites have a pronounced crustal within plate signature which is visible in lithology major and trace element geochemistry and the sr isotopic compositions these intrusions were dated using the pb pb single zircon evaporation method and yielded a triassic age of between 240 7 2 6 ma and 221 7 1 9 ma on 17 samples with a mean age of 228 3 5 6 ma the zircons are purely magmatic indicating that ages are primary crystallization ages a rb sr errorchron of the whole rock samples of the arnea granite yielded an age of 231 6 9 9 ma mswd 82 and a mean 87 sr 86 sr initial ratio is 0 7142 indicating a crust dominated source and suggesting an a type origin for the granites the a type meta granites together with mafic intrusive bodies amphibolites in the vertiskos terrane may be evidence of triassic rifting that led to the formation of a branch of neotethys vardar meliata ocean similar rock associations are also exposed in the cyclades and in massifs of the wider eastern mediterranean realm related to the gondwana derived hun terrane indicating that the arnea type granites are representatives of a major regional rifting event in triassic times

spectral characteristics of strong ground motions from intermediate depth vrancea seismic source abstract this study focuses on the investigation of spectral characteristics of ground motions recorded from intermediate depth vrancea earthquakes using newmark hall type response spectrum the database consists of more than 700 horizontal components recorded during 10 vrancea earthquakes in the first step of the analysis the component to component variability is assessed and the corresponding influence of various parameters earthquake magnitude peak ground acceleration soil class position of the seismic station or instrument type is evaluated subsequently the correlation between the spectral acceleration and the values of the peak ground motion parameters acceleration velocity and displacement is investigated the analyses reveal an important influence of the magnitude and a significant influence of the soil class in the case of large magnitude earthquakes on the results these findings are validated through the use of the analysis of variance anova method the computed response amplification factors for the newmark hall type spectrum are similar with those from other studies in the literature finally a check of three control periods such as t b t e and t f of the newmark hall type spectrum yields results somewhat different from the ones given in the romanian seismic design code p100 1 or in eurocode 8

attenuation in southeastern carpathians area result of upper mantle inhomogeneity the systematic analysis of seismograms recorded on the romanian territory using vrancea intermediate depth earthquakes shows a strong asymmetric pattern relative to the epicentral area on one side in the transylvanian basin and the eastern carpathians approximately along the inner volcanic chain the amplitudes are reduced by a factor of 20 on average and the high frequencies are attenuated in contrast with the other side in the foreland platform this pattern is explained by a significant attenuation increase caused by a strong lateral variation of the structure in the upper mantle immediately towards nw of the vrancea seismic active volume this region corresponds to the most recent volcanic activity in the persani mountains and with the low velocity body adjacent toward nw to the high velocity body subducted beneath vrancea area as indicated by seismic tomography and heat flow results the calixto 99 tomography experiment deployed for 6 months in 1999 provides the largest number of observations for vrancea earthquakes ever recorded on the romanian territory we select data from 8 earthquakes generated in this time interval in the vrancea nest which were recorded with signal noise ratio greater than 5 by at least 25 stations all of them are small to moderate magnitude events 3 6 mw 4 2 the attenuation is much more important in the high frequency range 1 hz than at low frequencies since the large vrancea earthquakes can radiate significant energy in the low frequency range 1 hz our results show that the seismic hazard level is much more uniform all over the romanian territory in the low frequency range than in the high frequency range

geodynamics and intermediate depth seismicity in vrancea the south eastern carpathians current state of the art abstract the vrancea region of the south eastern carpathians is a remarkable site of intra continental intermediate depth seismicity a large set of geological geophysical and geodetic observations has been accumulated for the last few decades and utilised to improve our knowledge of the shallow and deep structures beneath vrancea the crustal and mantle dynamics and the linkage between deep and surface processes in the region in this article we review geology and tectonics of the vrancea region including post collisional to recent deformations syn to post collisional magmatism and orogenic exhumation along the east and south carpathians the regional seismicity is analysed and the recent seismic studies including reflection refraction body and surface wave tomography are reviewed we discuss new geodetic measurements of horizontal and vertical movements in the region geoelectric studies density gravity and thermal modelling qualitative and quantitative including retrospective geodynamic models developed for vrancea are analysed the knowledge of regional tectonics geodynamics seismicity lithospheric deformation and stress regime in the vrancea earthquake prone region assists in an assessment of strong ground motion seismic hazard and risk the earthquake simulation seismic hazard and earthquake forecasting models have also been reviewed providing a link between deep geodynamic processes and their manifestation on the surface finally we discuss unresolved problems in vrancea in order to improve our understanding of the regional evolution present tectonics mantle dynamics intermediate depth seismicity and surface manifestations of the lithosphere dynamics and to enhance our ability to forecast strong earthquakes in the vrancea region the problems to be solved include i the origin of the high velocity body revealed by seismic tomography studies oceanic versus continental ii the lithospheric scale mechanism driving the miocene subsidence of the transylvania basin iii sub crustal structure between 40 and 70 km iv contemporary regional horizontal and vertical movements and v a comprehensive seismic hazard assessment in the region

damage stress and acoustic emission characteristics of the beishan granite crack initiation stress ci and crack damage stress cd of the beishan granite under uniaxial and triaxial compressions are determined

structural characteristics of two strong earthquakes in the north aegean ierissos 1932 and agios efstratios 1968 abstract structural analysis has been carried out on the volcanics of the island of agios efstratios and along the highly faulted zone of se chalkidiki south and north of the north aegean trough respectively northern greece the areas have been affected by strong earthquakes and a comparison is made between the available structural and seismological data together with new seismotectonic information at agios efstratios the earthquake of 1968 m7 1 occurred on a principal displacement zone with dextral strike slip movement while the fault geometry of the whole area supports the view of transtensional deformation the strong m7 0 earthquake of 1932 at ierissos was directly connected with an e w trending normal fault striations on the seismic fault surfaces and the corresponding fault mechanism indicate a n s direction of active extension the hangingwall is also affected by smaller antithetic e w and nw se trending structures