salt tectonics off northern israel the messinian evaporites in the eastern mediterranean represent a world class site to study thin skinned salt tectonic processes like gravity gliding or gravity spreading in contrast to the mesozoic evaporites in the atlantic the related structures are just slightly overprinted by additional tectonic events new high resolution reflection seismic data image for the first time the entire lateral succession of gravity gliding related features as they were suggested by analog models and demonstrate therewith the validity of those models for the messinian evaporites all three regimes of extension translation and compression are present within the range of the seismic profiles however additional observations lead to an adapted and improved model the generation of a critical slope angle caused by subsidence of the levantine basin is considered to be the main driving force for the thin skinned salt tectonics and the lateral basinward creep of the basinal messinian evaporites in the extensional section beneath or near to the continental slope where the basinal evaporites have been withdrawn listric and antithetic listric growth faults rollovers and keystone grabens form asymmetric turtleback structures above salt welds and salt rollers further basinwards an area with little or no deformation of the evaporites defines the translational segment in the compressional region the lower and thickest part of the evaporites show ductile deformation buckle folds and the upper evaporites reveal brittle deformation reverse faults and pop up structures here the basinal evaporites have a maximum thickness of about 1500 m the extensional zone shows continuous synsedimentary tectonic activity until recent times whereas the compressional structures have developed later in a rather sudden event there is clear evidence for neotectonics off the israeli coast which is not related to salt dynamics faults cut through the entire pile of evaporites and the post messinian overburden where the faults pierce the sea floor mud escape structures have been observed deep rooted faults have been interpreted at the base of the messinian paleo slope suggesting a shear zone off israel and parallel to the dead sea transform

rate of outward growth of the mediterranean ridge accretionary complex abstract the position as a function time of the deformation front on the southwest flank of the mediterranean ridge accretionary complex is constrained as follows 1 a the deformation front is now active 2 b the site of core ban84 05gc was still near the abyssal plain when displaced shallow water benthic foraminifera of inferred african provenance were redeposited within an upper pliocene age unit 3 c the site of core ban84 05gc on the outer flank of the mediterranean ridge was already within the topographically rugged accretionary complex when a pliocene debris flow was emplaced 4 d dsdp site 125 had already been uplifted into a topographically elevated position when lower pliocene pelagic ooze was deposited 5 e a gypsum bearing breccia in dsdp site 125 requires that the site was either on the abyssal plain or within the tectonically active outer perimeter of the accretionary complex during the messinian salinity crisis 6 f dsdp site 377 had already been uplifted into a topographically elevated position when middle miocene age pelagic marl was deposited 7 g dsdp site 377 was still on or near the abyssal plain when early to lower middle miocene age smectite bearing turbidites of inferred african provenance were deposited and 8 h the mediterranean ridge began to grow by offscraping against a backstop formed by the alpine nappes of the hellenic arc at the time that subduction began 33 ma together these constraints define a range of potential growth curves for the mediterranean ridge with a rate of outward growth of approximately 0 5 to 2 cm yr this growth rate is faster than that inferred for most other modern accretionary prisms both as an absolute value and as a fraction of the subduction velocity an unusually thick incoming section and or an unusually weak evaporitic decollement may contribute to the rapid growth rate the inferred age of accretion does not increase linearly with distance from the deformation front rather there is an apparent acceleration of the rate of outward growth through time this observation may reflect a true acceleration of growth rate in response to the onset of back arc extension in the overriding plate aegean sea and or in response to the development of a weak basal decollement following the introduction of halite into the incoming stratigraphic section alternatively the non linearity of the age vs distance curve may indicate that shortening of the offscraped sediments continues across the breadth of the mediterranean ridge rather than being confined to the outer flank

strain distribution over the east mediterranean ridge a synthesis incorporating new sea beam data abstract we present the results of several multi narrow beam sea beam traverses of the mediterranean ridge on board r v jean charcot these results can be considered to be complementary in resolution and coverage to the previously published long range side scan sonar gloria results a characteristic of the mediterranean ridge is the presence over about half of its surface of an extensive fold system affecting the messinian and plio quaternary cover which is dissected by conjugate strike slip faults the resolution of sea beam was used to map the main characteristics of folding and faulting this analysis together with previously available data enables us to define the strain pattern over the mediterranean ridge we thus now have an overall view of the strain pattern from a marginal basin aegea through the hellenic trench and adjacent sea floor to the opposite continent the bottom of the hellenic trench is a boundary between an extensional domain to the north and a compressional one to the south the southern domain is strongly affected by the presence of the lybian promontary it is related to the formation of an accretionary ridge due to the inability of the upper 3 4 km of sediments to subduct this ridge is similar to the accretionary prism but it is much wider with respect to its height probably because of the existence of a decollement over a level of overpressure the hellenic trench then is in the situation of a fore arc basin its origin is due to the fact that the aegean continental slope is not vertical but rather has a small 4 dip as a result a sedimentary wedge symmetric but shorter than the main accretionary wedge develops over the buried portion of the slope it is characterized by landward thrusts such an origin probably applies to fore arc basins in general

from foreland to forearc domains new multichannel seismic reflection survey of the mediterranean ridge accretionary complex eastern mediterranean abstract the mediterranean ridge of the eastern mediterranean sea is a huge accretionary wedge emplaced as a consequence of the africa aegean plate convergence that has a rate estimated at 40 mm yr processing of recent multichannel seismic data and integration with previous results seismic profiling swath bathymetry sonar have facilitated the study of the overall deformation pattern of the area which includes three distinct major structural domains facing various forelands 1 1 the outer domain is bounded southward by the present day wedge toe and towards the north by topographic slope breaks and clear changes in deformational style beneath the ionian and levantine mediterranean ridge branches the base of messinian evaporites seems to act as a major decollement level 2 2 the central or crestal domain the shallowest one shows evidence of mud diapiric and mud volcano activity and is overthrusting northward over the inner domain facing the libyan margin this area which displays spectacular mud volcano fields appears much wider and shallower 3 3 the less deformed inner domain is bounded northward by the hellenic trench system beneath its ionian inner area seismic velocities characteristic of continental crust have been recorded while within its levantine region it is made of a series of disconnected and uplifted basement blocks strabo seamounts along the matapan and pliny trenches structures which could be caused by transpressive deformation are locally observed we believe that both the north south structural arrangement and the clear west east lateral variations of the mediterranean ridge relate to its progressive collision against the libyan margin promontory this event which may have initiated 5 6 myr ago may have induced a a differentiated paleogeography of messinian evaporites later available for tectonic accretion leading to the further lateral structural variations of the outer domain and b strain partitioning between the central mediterranean ridge and the hellenic trench system

seismic velocities from the barbados ridge complex indicators of high pore fluid pressures in an accretionary complex three wide aperture 0 5 km offset seismic profiles were shot perpendicular to the strike of the barbados ridge accretionary complex at 16 12 n line 465 14 23 n line 480 and 13 20 n line 484 to image the deep structure of the accretionary complex and obtain seismic velocity data velocity analyses on full fold common depth point cdp gathers were used to provide velocity depth functions at 1 km separation along each line to map the variation in velocity with depth and distance across the accretionary complex the sediments within the complex show consolidation increasing laterally with greater age of the complex as indicated by the increase in seismic velocity and the inferred decrease in porosity the velocity at the base of the wedge along line 480 is 2 4 km s at the toe the velocity at the wedge base at 60 km from the toe where the wedge thickness has increased from 1 8 km to 5 0 km has increased to greater than 3 0 km s however the velocities within the leading margins and within undeithrust sequences in each of the three sections are low as much as 1 0 km s less than velocities found in undeformed sedimentary sequences of equivalent thickness the low velocity regions are interpreted as sediments with high porosity where porosity is inferred to be high pore fluid pressures are also inferred to exceed hydrostatic and pore fluids actually support the increased lithostatic load produced by recent thrusting and thickening of the complex the correlation between the most rapidly thickened regions and the velocity anomalies suggests that a rapid rate of loading relative to the rate of pore fluid expulsion produced these overpressured sediments velocities in the underthrust sequences where the differences between loading histories of wedge sediments and the underthrust sequences are largest are sufficiently low to produce velocity inversions low velocities also occur in regions adjacent to the complex where the pore fluid pressures may be elevated by the pressure produced in the adjacent wedge west of the wedge in the forearc basin along line 480 and near a seismically imaged mud diapir velocities at a depth of 3 5 km below the seafloor are 0 5 km s less than what is expected in a more normal sedimentary section immediately seaward of the complex the deepest undeformed sequences have a velocity anomaly of 0 5 km s velocities remain low for at least 12 km seaward of the complex but they become closer to a more normal sediment section farther from the wedge

first paleomagnetic results from mio pliocene series of the hellenic sedimentary arc abstract paleomagnetic measurements have been conducted on the mio pliocene series along the external sedimentary hellenic arc in order to detect the presence or absence of rotational deformations in different sections of the arc in the central eastern part of the arc crete and rhodes paleomagnetic directions are very closely aligned along the north south direction showing that this portion of the arc has not undergone significant rotation since at least 7 m y for crete and 4 m y for rhodes in the western and northwestern parts results from south peloponnesos zakinthos kephallinia and corfu indicate that this section of the arc has undergone a clockwise rotation detailed analysis of the data from the three ionian islands shows that their rotation began about 5 m y b p and has proceeded since then at roughly 5 m y giving a total amplitude of about 26 it is suggested that the beginning of this rotation is related to the lower pliocene compressive phase which most probably initiated the tectonic activity of the present day ionian margin

single bubble air gun array for deep exploration large tuned air gun arrays operated in off shore petroleum exploration are also used for deep penetration marine seismic reflection surveys conducted to define structures in the earth s crust because of the attenuation of higher frequencies the useful upper frequency limit of these records is usually about 50 60 hz the aim of this paper is to report on a method of seismic pulse generation that preferentially concentrates the air gun s energy in the low range of the seismic frequency band by centering the output on the first bubble pulse instead of the initial primary pulse experimental results show that due to the increased low frequency energy content of this single bubble pulse air gun arrays considerably reduced both in size and volume can generate the necessary acoustic energy for deep seismic exploration

modeling of large scale accretionary wedge deformation instantaneous stress and velocity fields within an active accretionary wedge can be calculated using plastic slip line theory given the assumptions of a perfectly plastic rheology and plane strain conditions after selecting a plastic yield stress and an average density a stress field slip line field can be computed for a wedge of known cross sectional configuration from known stress boundary conditions on the upper surface basal surface tractions are derived without basal boundary conditions the geometry of the computed slip line field can then be used to constrain the lower limit of the yield stress the known velocity boundary conditions are insufficient for calculation of a velocity field because the coupling between the wedge and the subducting plate is unknown consequently basal velocity distributions must be assumed to permit the construction of velocity fields these assumed distributions are constrained by known rates of surface uplift and rates of tilt as well as inferred patterns of instantaneous strain rates within a wedge the sunda accretionary wedge west of central sumatra is used to illustrate the plasticity approach a minimum average yield stress of 20 30 mpa and a weaker basal layer of variable effective strength are indicated for this example surface uplift rates may be affected significantly by regions of high basal strain rate finite velocity discontinuities and underplating the known pattern of uplift rates near nias island located on the outer arc ridge is consistent with the constraint that 90 of the total incremental shortening of the wedge is concentrated within 20 km of the trench given a sufficient number of uplift and tilt rate observations across a particular wedge the relative influence of underplating tectonic erosion and basal strain rate variations could be assessed using the perfectly plastic model

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

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

deformation of the western mediterranean ridge importance of messinian evaporitic formations abstract multichannel seismic data were acquired across several areas of the mediterranean ridge m r in the eastern mediterranean sea during the mcs prismed survey march 1993 the m r is a wide high standing and elongated swell emplaced between the southern aegean and africa as a consequence of the long term convergence and the ongoing collision between europe and africa sedimentary piling and associated deformation have built a thick deformed sediment wedge the internal geological structures of which remain poorly understood processing of two mcs lines pm 02 and pm 03 across the western branch of the mediterranean ridge reveals that messinian evaporite bearing formations which were deposited within the deep ionian oceanic basin 5 my ago play an important part in the present structural deformation of the m r accretionary wedge within the outer m r the messinian lower evaporites are believed to act as one of the main decollement levels while the top of these formations may operate as a disharmonic layer below thin plio quaternary sediments the present day m r toe appears to be affected by ductile flow deformation however most of the accreted outer wedge is believed to have resulted from the progressive piling up and associated thrusting of messinian and overlying plio quaternary sediments toward the northeast i e toward the central m r domain a major backthrust zone indicates a structural boundary between the outer wide and convex m r and its inner rather flat domain which is inferred to act as a backstop

physical properties and state of the crust and upper mantle of the eastern mediterranean sea deduced from geophysical data abstract by evaluating the geophysical information available for the eastern mediterranean sea ems a crustal thickness map and some conclusions as to the nature of the crustal type were drawn it was found that the ionian abyssal plain is floored by an oceanic type of crust which is 14 km thick and covered by sediments of the order of 8 km thick the herodotus abyssal plain in the levantine sea is floored by a crust 22 km thick and covered by sediments ranging between 10 and 15 km thick the eastern mediterranean rise extending more or less continuously from the apulian plateau to rhodes and the south of the antalya basin is of a thickness ranging between 28 and 34 km the thickness of its sedimentary cover is of the order of 10 km the borders of the eastern mediterranean sea are built up of thick continental crust for example the hellenides of western greece range between 40 and 44 km thick and western turkey has a similar crustal thickness the crust of sicily also exceeds 40 km whereas the southern and eastern borders of the ems are approximately 30 32 km thick tectonically the northern border of the ems is built up of active continental margins defined by the calabrian hellenic and cyprus antalya arcs whereas the southern border represents a passive continental margin controlled mainly by subsidence and stretching to the east the dead sea megashear limits the area the deep basins of the eastern mediterranean sea are tectonically controlled by subsidence and partial stretching the mediterranean ridge or rise is still an area of dispute regarded by some authors as a subsiding continental fragment and separated from the hellenic arc by the hellenic trench whereas others consider it to be a zone of crustal shortening thickened mainly by thrusting both the western and southwestern borders of the mediterranean rise and the hellenides are controlled by compressional processes similar to those deforming the calabrian arc the stravo and pliny trenches to the east southeast border of the hellenic arc are partly affected by strike slip movements various plate tectonic models of the area have been proposed by several authors though the complexity of the deformation hardly permits reliable reconstructions the lack of reliable paleomagnetic information and the absence of linear magnetic anomalies do not favour the application of plate tectonic concepts vertical processes due to the uprising of lithothermal systems below the hellenic and calabrian arcs may also be regarded as the driving force controlling the present day deformation

geological structures on the south cretan continental margin and hellenic trench eastern mediterranean abstract combination of recent seismic profiles obtained along the south cretan continental margin with previously published data has provided a basis for mapping the overall structure of this portion of the active hellenic margin two sectors are distinguished from western crete to 25 east the continental slope is crossed by post late miocene extensional features creating a series of sedimental marginal troughs and steep basement ridges the lower slope the trench and parts of its outer slope are areas of little sedimentation most of the sediments are trapped on the margin and of active deformation this area represents the eastern prolongation of the ionian branch matapan trench of the hellenic subduction zone and is interpreted in the light of ne directed compression from 25 e to eastern crete the geological structures of both the continental margin and the adjacent trenches differ from those to the west this difference possibly relates to interferences between the present day structural directions interpreted in relation to a left lateral transform motion and previous trends inherited from a preceding ns compression

coulomb theory applied to accretionary and nonaccretionary wedges possible causes for tectonic erosion and or frontal accretion based on observations from both modem convergent margins and sandbox modeling we examine the possible conditions favoring frontal accretion and or frontal and basal tectonic erosion mean characteristic parameters t t and are used to discuss the mechanical stability of 28 transects across the frontal part of convergent margins where the coulomb theory is applicable natural observations reveal that typical accretionary wedges are characterized by low tapers with smooth surface slope and subducting plate low convergence rates and thick trench sediment while nonaccretionary wedges display large tapers with irregular surface slopes and rough subducting plate high convergence rates and almost no trench fill sandbox experiments were performed to illustrate the effects of seamounts ridges in the subduction zone on the deformation of an accretionary wedge these experiments show that a wedge of sand is first trapped and pushed in front of the seamount which acts as a moving bulldozer this is followed by a tunnelling effect of the subducting seamount through the frontal wedge material which results in considerable sand reworking at an advanced subduction stage the d6collement jumps back from a high level in the wedge to its former basal position we conclude that a high trench sedimentation rate relative to the convergence rate leads to frontal accretion in contrast several conditions may favor tectonic erosion of the upper plate first oceanic features such as grabens seamounts or ridges may trap upper plate material during their subduction process second destabilization of the upper plate material by internal fluid overpressuring causing hydrofracturing is probably another important mechanism

movement of lithics by trampling an experiment in the madjedbebe sediments northern australia understanding post depositional movement of artefacts is vital to making reliable claims about the formation of archaeological deposits human trampling has long been recognised as a contributor to post depositional artefact displacement we investigate the degree to which artefact form shape and size attributes can predict how an artefact is moved by trampling we use the zingg classification system to describe artefact form our trampling substrate is the recently excavated archaeological deposits from madjedbebe northern australia madjedbebe is an important site because it contains early evidence of human activity in australia the age of artefacts at madjedbebe is contentious because of the possibility of artefacts moving due to trampling we trampled artefacts in madjedbebe sediments and measured their displacement as well as modelling the movement of artefacts by computer simulation artefact elongation is a significant predictor of horizontal distance moved by trampling and length width thickness and volume are significant predictors of the vertical distance the explanatory power of these artefact variables is small indicating that many other factors are also important in determining how an artefact moves during trampling our experiment indicates that trampling has not contributed to extensive downward displacement of artefacts at madjedbebe

long term agrarian landscapes in the troodos foothills cyprus abstract we investigate the temporal and environmental relationships between the terraced hill slopes of politiko koloiokremmos and the adjacent bronze age settlement of politiko troullia in foothills of the troodos mountains central cyprus mapping of 102 stone walls on koloiokremmos is compared with 66 walls farther afield on cyprus to create a six part terrace typology sherd counts from 174 2 m radius collection circles over approximately 20 ha on troullia and koloiokremmos were used to create interpolated sherd density surfaces revealing distinctly different patterns of land use for four major archaeological eras between the cypriot bronze age and medieval period we compared sherd density patterns according to terrace types length slope and vegetation cover determined by savi soil adjusted vegetation index from ikonos and quickbird satellite imagery the most robust sherd patterning indicates prehistoric bronze age settlement at troullia as confirmed by soil resistivity and excavation and multi period land use on koloiokremmos immediately upslope of the village that may be associated with agricultural terracing scattered sherd concentrations indicate later use of this landscape as an agricultural hinterland for the iron age city of tamassos sherds and a down slope spread of roof tiles from the roman through medieval periods suggest an isolated structure near the crest of koloiokremmos longer terraces correlate with greater vegetation cover and are interpreted as agricultural while shorter terraces apparently for erosion control and arboriculture are significantly related to prehistoric bronze age sherd patterns our results suggest that coordinated analysis of archaeological geographical and remotely sensed environmental data associated with terraced landscapes can be used to infer long term patterns of agricultural land use

a fluid model for the shape of accretionary wedges in this paper the accretionary wedges landward of most oceanic trenches are modelled assuming a newtonian fluid rheology it is shown that lubrication theory is applicable and that the addition of material to the wedges can be neglected in determining the shape of the wedges the predicted shape of the wedges is in good agreement with bathymetric profiles across the kurile ryukyu and aleutian wedges from the shape of the above wedges it is deduced that accretionary sediments have viscosities between 1018 and 1019 poise

structural sketch of the hellenic continental margin between the western peloponnesus and eastern crete a structural sketch of the hellenic continental margin and adjacent areas based on numerous seismic profiles obtained in the past few years shows two distinct structural domains an inner extensional domain characterizes most of the continental margin the offshore regions as well as the cretan sea an outer compressional domain extends over the trenches and part of their outer slope we believe that this perplexing pattern is related to the presence of an underlying evaporitic series progressively deformed and piling up against a resistant continental margin the completion of subduction and subsequent continental collision are also involved in this structural framework

mud volcanism on the mediterranean ridge initial results of ocean drilling program leg 160 drilling during ocean drilling program leg 160 april may 1995 revealed important new evidence concerning the internal composition depositional processes and age of two mud volcanoes within the mediterranean ridge accretionary complex holes were drilled at ca 2000 m water depth on the crest areas across the flanks of the mud volcanoes and onto adjacent deep sea sediments the main depositional units forming the flanks of both mud volcanoes are debris flows mud breccias composed of a volumetrically dominant mud matrix containing clasts of mainly clay mudstone siltstone sandstone and limestone more variable muddy silty and sandy sediments were recovered from the crestal areas of both volcanoes the lowest mud volcano units drilled include well sorted medium to coarse grained sediments mainly composed of clay that were deposited partly by turbidity currents the mud volcano sediments are associated with background deep sea sediments that allow dating by using microfossils the milano mud volcano is at least 1 75 ma and is apparently now dormant and the napoli mud volcano started prior to or during 1 5 1 2 ma and is currently active pore fluids at napoli and to a lesser extent at milano indicate the presence of halite of presumed latest miocene age beneath the volcanoes hydrocarbon gas is venting from the crest of the napoli mud volcano and gas was also detected on the crest of the milano mud volcano methane hydrates clathrates are also inferred to exist beneath the crest of the milano mud volcano the mud volcanoes are located above a shallowly dipping subduction zone in an area where the accretionary complex is apparently being thrust northward over a backstop of continental crust related to initial collision of the african and eurasian plates mud volcanism may have begun when backthrusting punctured a seal of latest miocene evaporites allowing the escape of overpressured materials

the hellenic subduction zone a tomographic image and its geodynamic implications new tomographic images of the hellenic subduction zone demonstrate slab penetration in the aegean upper mantle to depths of at least 600 km beneath greece the lower part of the slab appears to be detached at a depth of about 200 km whereas it still seems to be unruptured beneath the southern aegean schematically we derive minimum time estimates for the duration of the hellenic subduction zone that range from 26 to 40 ma this is considerably longer than earlier estimates which vary between 5 and about 13 ma

simulation of artefact movement due to cultivation abstract the disturbance of archaeological material in the ploughsoil due to cultivation is a problem of great and increasing importance using the results of experimental investigations at the butser ancient farm project it has been possible to derive a mathematical model for the effect of cultivation on assemblages of material in the ploughsoil the model uses a probability density function to represent the effect of cultivation various implementations are described and the model has been applied to a number of material distributions both artificial and real the results of these studies illustrate the importance of cultivation induced movement in the formation of archaeological assemblages in the ploughsoil

the horizontal velocity field in the deforming aegean sea region determined from the moment tensors of earthquakes we use the spatial distribution of seismic moment tensors of earthquakes in the aegean region over the time interval 1909 1983 to recover a continuous horizontal velocity field that describes the overall deformation of the lithosphere at large length scales the calculated velocity field is dominated by two effects 1 an e w right lateral shear of the eastern aegean related to motion on the north anatolian fault becoming distributed as it enters the aegean and 2 a n s extension probably related to the sinking of the slab in the hellenic trench the southern part of the central aegean is found to be moving in a sw direction relative to europe at a rate of about 30 mm yr probably a lower bound with an error of around 10 mm yr and rotating clockwise in the seismogenic upper crust this velocity field is accommodated by right lateral strike slip faults in the eastern aegean and by normal faults that rotate clockwise in central greece a comparison of paleomagnetic declination data with the expected rotation of rigid elongate inclusions in the velocity field shows in most places an agreement in sense and approximate agreement in rate of rotation expected rotation rates of line elements are sometimes too low probably because our derived velocity field is smoothed and unable to match locally high strain rates there is only one part of the region where line elements are predicted to rotate in either clockwise or counterclockwise directions depending on their orientation this is in western turkey which coincident ally is the only place where paleomagnetic rotations in both directions have been observed this coincidence in particular suggests to us that the analogy of rigid elongate inclusions in the velocity field responding to forces on their bases may be useful in predicting the senses and approximate rates of rotation of crustal blocks in deforming continental regions the velocity field we obtain preserves the strike directions of the major faults as directions of zero length change in spite of considerable smoothing we use this observation to speculate that the interaction between the upper crust and the rest of the lithosphere beneath it may involve an interplay of effects on one hand the variation of strength with direction in the crust may control the strike directions of faults that form or become reactivated and may also limit the velocity fields that are allowable on the other hand the fault bounded blocks may rotate in the velocity field in response to forces on their bases which would require the velocity field to change with time if the directions of zero length change are fixed to the blocks

large scale laboratory measurements of solitary wave inundation on a 1 20 slope abstract the run up flow and related pressure of solitary waves breaking on a 1 20 plane beach were investigated experimentally in a super tank 300 m 5 m 5 2 m swash flow measurements of flow velocities are compared with an existing analytical solution by incorporating an analytical solution the hydrodynamic pressure for a quasi steady flow state is determined and compared with laboratory data concerning the evident extra pressure exerted by the impact of swash flow an empirical drag coefficient for a circular plate is also suggested in the present study

structure of the nankai trough accretionary zone from multichannel seismic reflection data new multichannel seismic reflection data collected over the nankai trough image the accretionary complex in two areas the international program of ocean drilling leg 87 transect area western area and the region of upcoming ocean drilling program leg 131 eastern area the incoming shikoku basin sedimentary section consists of hemipelagic clays and thin terrigenous turbidites the basin section is overlain by a trench wedge that is 12 16 km wide and 350 750 m thick at the thrust front accretionary deformation begins in a protothrust zone that is characterized by thickening and seaward tilting of the trench wedge the zone in the western area is 4 5 km wide and is characterized by kink folds the zone in the eastern area is only 2 5 km wide and does not exhibit such folds the frontal thrusts in each area are imaged as fault plane reflections and ramp upward from within the basin hemipelagic section the overthrusting sediments form fault bend folds over these ramps thrust spacing at the toe of the slope is 1 5 2 5 km the second thrust cuts up from an inferred decollement within the shikoku basin sedimentary section in the eastern area a reflection marking the top of the basin pelagic sediment section changes from normal to reversed polarity about 6 3 km seaward of the thrust front and underlies the entire protothrust zone this reflector continues with reversed polarity under the accretionary complex and is at the level of the basal decollement the underlying basin pelagic section is apparently thrust undisturbed beneath the accretionary prism the reversal of polarity indicates a change in reflection coefficient that is due to a combination of decreasing seismic velocity and density across the interface this decrease in velocity and density may indicate that the decollement is a zone of high porosity due to fluid expulsion from deeper within the accretionary prism the reflections from the first and second thrusts are also reversed polarity possibly indicating that they also are pathways of fluid expulsion the critical wedge taper of the western area is greater than that of the eastern area an observation that is consistent with the existence of an overpressured decollement in the eastern area

the structure and evolution of the western mediterranean ridge the mediterranean ridge is a unique accretionary complex consisting of five key elements the frontal slope the upper slope the crest of the ridge the cleft area and the inner plateau the imerse data show that these correspond roughly to the locus of frontal accretion of underplating of a pre messinian wedge of complex faulting and possible strike slip tectonics and of a backstop of hellenic nappes covered by a messinian forearc basin the frontal portion of the complex is a post messinian accretionary wedge composed of messinian evaporites and overlying tightly folded plio quaternary sediments underlain by pre messinian sequences attached to the african plate the basal detachment at the front of the wedge occurs at the base of the evaporites moving further to the northeast the upper slope the basal detachment cuts to deeper levels leading to the development of duplex structures where pre messinian units are subcreted beneath the messinian evaporites just behind the subcreted units the evaporites thin and may be absent on the crest of the ridge this region we interpret as the site of a pre messinian accretionary wedge we suggest that following the deposition of thick evaporites in the messinian the pre messinian accretionary tectonics continued as subsurface accretion subcretion beneath the evaporites although the crest of the ridge is largely devoid of evaporites local deep evaporite basins observed here formed as local closed basins on top of the pre messinian wedge we infer that the messinian sealevel was at about the level of the ridge crest that is 3000 m below present allowing for isostatic adjustment to the removal of the water load this would imply a sealevel drop of at least 2000 m the cleft basins mark the northeast limit of the accretionary complex thick evaporite deposits to the northeast beneath the inner plateau may have been deposited in a messinian forearc basin the evaporites of the inner plateau are underlain by a thin pre messinian sequence and by crystalline basement of the hellenic nappes this basement forms the backstop to the accretionary complex

origin of convex accretionary wedges evidence from barbados the surface slopes of submarine accretionary wedges generally decrease away from the toe or defor mation front toward the arc this paper presents evidence that this characteristic convex cross sectional shape is a direct mechanical response to the lithification of sediments during accretion the recently accreted sediments near the toe which are typically unconsolidated and therefore very weak must deform until a critical taper is attained at which they are stable in the presence of the horizontal tectonic compression this critical wedge taper and thus the bathymetric slope of the accretionary prism is relatively high for the porous weak sediments near the toe in contrast the compacted sediments farther back in the wedge are stronger so they require a relatively modest critical taper and therefore a lower bathymetric slope to be stable under the same tectonic compression the result is a convex cross sectional wedge shape we investigate several possible causes of the increase in sediment strength within the wedge and conclude that the primary cause is an increase in cohesive strength with decreasing porosity a straightforward generalization of the exact critical taper model is combined with empirical cohesion porosity velocity relations to infer the distribution of porosity and p wave velocity within the barbados accretionary wedge we estimate that the porosity decreases from its near toe value of 70 to approximately 30 at a depth of 3 km below the seafloor and a distance of 60 km arcward from the front of the wedge

the mediterranean ridge and related mud diapirism a background abstract the mediterranean ridge stretching from the calabrian rise to the florence rise is the largest structural unit of the eastern mediterranean sea it is directly related to ongoing convergence and collision of the african and eurasian plates starting in the oligocene and is considered to be a giant accretionary complex consisting of intensively folded and faulted rocks of the african margin since its origin in the late miocene the ridge continued to grow up and outward experiencing more deformation because of the developing collision the mud diapirism and mud volcanism are usual and wide spread phenomena for the mediterranean ridge that developed as a result of an intensive tectonic overburden due to stacking of rock units by thrusting and strong lateral compressional stress pressing up and squeezing plastic sedimentary series out onto the seafloor

textural pedofeatures and pre hadrian s wall ploughed paleosols at stanwix carlisle cumbria u k abstract during the last 30 years the value of sandy silty or dusty textural pedofeatures for identifying past agricultural practices has been the subject of debate particularly with regard to the applicability of modern analogue observations to ancient soils macro and micromorphological analyses were carried out on all the contexts in a series of five trenches containing pre roman plough grooves in moderately sandy buried soil profiles at sites near hadrian s wall cumbria micromorphological observations of 31 thin sections showed that the pedofeatures in question were not preferentially distributed in thin sections of sediments from within or below the plough layers but were more concentrated in contexts which as shown by field and archaeological evidence were unlikely to have been affected by cultivation conversely the pedofeatures were absent in other thin sections of sediments from and below the contexts where past agriculture was documented by field and archaeological features the analysis also showed that the pedofeatures in question tended to be distributed in parts of the sequence with suitable porosity soil structure and texture rather than in relation to the position of the cultivated layers all the results in this case study showed that silty sandy and dusty pedofeatures were not diagnostic for past agricultural practices and highlighted the need for more research on the micromorphological evidence of ancient soils with a known record of past agriculture

on the shape of the subducting slab beneath the peloponnese greece the mediterranean sea floor is subducted beneath the western hellenic arc at a gentle angle for about 200 km and then steepens beneath the gulf of corinth the seismic zone extends to a depth of 150 km but the subducted intact lithosphere could reach 600 km the present relative motion between africa and aegea can be considered as the sum of 2 motions 1 slow 1 cm y relative motion between africa and europe which describes the rate at which the deep slab penetrates the asthenosphere and which started during the upper cretaceous time when africa started to converge toward europe and 2 fast 5 cm y relative motion between the southern aegea and europe manifest by internal deformation within the aegean which may have been active at present rates only since pliocene time i suggest that the increase in the total convergent rates which began about 5 my ago is responsible for the wide flat slab beneath the peloponnese

spatial transition from compression to extension in the western mediterranean ridge accretionary complex the mediterranean ridge has been described since 1982 as an accretionary prism related to the hellenic subduction zone however little attention has been paid to the actual mechanical boundary between the sedimentary wedge and the crustal backstop of the outer hellenic arc using seismic velocity structures from recent esp s pasiphae cruise we propose a new interpretation of existing geological and geophysical data around the western hellenic trenches the velocity structure of the inner unit of the mediterranean ridge suggests that the late neogene to quaternary sequences were deposited above a high velocity rigid body we propose to correlate the boundary of this rigid body backstop of the accretionary wedge with a series of oblique reflectors dipping to the southwest near dsdp sites 126 and 377 the backstop extends further south than previously thought and decreases by one third the total width of the compressional wedge it has thus major implications on the volume of accreted material the short wavelength folding of plio quaternary sediments observed on the outer wall of the south matapan trench is probably a consequence of gravity gliding layers above the high velocity body gently dipping 2 to the northeast using the messinian evaporite as a decollement on the other hand the hellenic trenches appear to be narrow half grabens affected by the widespread extensional deformation active on the outer hellenic arc they are situated on the landward boundary of a wider and poorly sedimented fore arc basin we conclude that extensional deformation extends at least over the width of the hellenic trenches on the continental side of the backstop whereas compressional deformation stops near the edge of the backstop itself 100 km to the southwest

the crust of the western mediterranean ridge from deep seismic data and gravity modelling summary we present a crustal cross section of the western mediterranean ridge from the african margin to the aegean sea constrained by the morphology of the ridge new seismic reflection and refraction results obtained during a two ship cruise performed in december 1988 pasiphae cruise the distribution of seismicity and gravity modelling morphologically the western mediterranean ridge can be divided into three main units from the sirte abyssal plain to the hellenic trench a broad outer unit a narrow central unit and an inner unit the seismic front orgeaward extent of the interplate seismicity between the african lithosphere and the cretan arc is located 50 km seaward of the hellenic trench seismicity is thus distributed widely over the innermost unit of the ridge suggesting that brittle material is present at shallow depth beneath the inner portion of the mediterranean ridge the refraction results of the pasiphae cruise show that the crust in the ionian basin and beneath the outer and central units of the western mediterranean ridge is oceanic and that the moho discontinuity progressively deepens towards the hellenic arc in agreement with the accretionary prism model high velocity material occurs at shallow depth beneath the innermost unit of the ridge gravity modelling also indicates a significant increase in density beneath the inner unit we consequently interpret the inner unit of the ridge as the backstop of the western mediterranean ridge prism possibly composed of peloponnesus thrust sheets

heat flow tectonics and fluid circulation at the toe of the barbados ridge accretionary prism detailed patterns of near surface tectonics and heat flow were investigated at two locations at the toe of the barbados ridge accretionary prism at the two locations in the thickly sedimented southern portion of the prism near 12 20 n and in the northern area drilled during ocean drilling program odp leg 110 near 15 32 n relative highs of heat flow were associated with zones of thrusting we attribute them to upward advection of water rising from the decollement along faults through the sediments in the odp area a significant heating plate effect from warm fluids flowing along the decollement and thrusts is required to account for the high regional heat flow this effect implies high rates of fluid flow at the decollement which can only be non steady state or would require massive lateral transport of fluids along strike

tectonics of the hellenic trench a synthesis of sea beam and submersible observations abstract detailed bathymetric investigations were performed in four zones of the hellenic trench system in 1978 using the multi narrow beam echo sounder sea beam on r v jean charcot in 1979 a field study using the 3000 m submersible cyana was conducted in three of the four sites covered by sea beam we summarize here the principal tectonic results of these studies and publish the corresponding sea beam maps it is shown that compressional structures affect the sedimentary cover of the outer wall and trench whereas extensional tectonics is present on the inner wall in addition there is evidence that most of the upper sedimentary cover is not subducted but rather piles up in front of the trench to form the mediterranean ridge we suggest that the surface limit of the zone of mechanical decoupling occurs near the base of the inner wall we show that the gross structure of the trench as well as the strain pattern observed is controlled by the kinematics of subduction and we discuss its evolution since its initiation about 13 m y ago

calcaires mesozoiques dans les fosses helleniques implications paleogeographiques et geodynamiques abstract at two dredge and one coring stations on the lowermost slope of the hellenic trench eastern mediterranean within the area heat ii south of gavdos limestone samples showing two distinct facies were recovered the first facies which contains rudists algae and foraminifera is a neritic limestone dated at late albian to early cenomanian age the second facies corresponds to a neogene micrite the occurrence of karstified calcareous formations of probable alpine hellenic units previously interpreted as partly dissolved messinian evaporites at 3000 m depth is discussed in terms of three hypotheses pre messinian karstification messinian karst and recent submarine dissolution in the light of the present geodynamic evolution of the hellenic margin we favor the hypothesis of a pre messinian karst now deeply submerged

tomographic images of the upper mantle below central europe and the mediterranean results from delay time tomography of the european mediterranean upper mantle are discussed and where possible interpreted in terms of geodynamic processes slab like positive velocity anomalies of which the locations correlate well with deeper seismicity are found beneath spain the tyrrhenian basin and the aegean these structures are interpreted as images of subducted slabs large aseismic regions with positive velocity anomalies are found beneath the western mediterranean italy the alps dinarides the pannonian basin northern greece and the aegean these anomalies can also be linked to subducted lithosphere from the anomaly patterns it is deduced that subduction occurred below the western mediterranean and along both sides of the adriatic micro plate beneath the dinarides and northern greece the velocity structures suggest detachment of the slab from the surface

accretion structural style and syn contractional sedimentation in the eastern mediterranean sea we analyse four multichannel seismic profiles collected by ogs from 1971 to 1979 along the outer part of the mediterranean ridge accretionary complex in order to understand the nature of the deformation affecting african plate sediments as they approach the africa europe plate boundary tectonic style as revealed by our data and previous studies varies considerably along the plate boundary and this variation suggests the division of the margin in three provinces characterised by different structural patterns and deformation rates 1 near orthogonal terminal subduction initial collision ionian and sirte foredeeps 2 incipient continental collision collision of continental promontories of the african margin off the cyrenaica peninsula 3 oblique terminal subduction initial collision herodotus foredeep this work aims to relate the tectonic features revealed by the seismic profiles to the geodynamic and stratigraphic parameters of the convergent margin these are essentially related to the geometry of subduction rate of convergence and obliquity and to the lithology of the incoming sedimentary section as well as the accumulation rate in the foredeep in the sirte province accumulation rate in the foredeep is relatively low and deformation is related to thrusting and folding which accounts for sediment shortening and uplift at the outer deformation front in the provinces of oblique terminal subduction the rate of normal convergence is lower the sedimentary section is thicker and the foredeep fed by the nile river has an higher syn tectonic sedimentation rate here deformation produces a broad band of large wavelength and high amplitude folds folding in this area is produced both by plate convergence related shortening and by movement of salt triggered by differential loading of the prograding nile deep sea fan in the area of incipient continental collision the foredeep is a v shaped trough as the abyssal plain has been completely subducted and the folded sediments of the accretionary complex rest directly on the african continental slope such differences in structural style are explained by great differences in strain rate that in the herodotus foredeep province has been calculated as at least four times weaker than in the western sector two factors contribute to decrease strain rate syn contractional accumulation and normal component of the effective convergence rate the former increases from west to east and possibly causes overpressuring on the decollement level salt mobilisation landward and seaward vergent folding and a very low surface taper in the herodotus foredeep the latter decreases from west to east and favours thrusting in the western sector

shallow structure and recent evolution of the aegean sea a synthesis based on continuous reflection profiles abstract a dense grid of continuous seismic reflection profiles partly calibrated with drilling results has allowed construction of a structural outline of the entire aegean sea in the north aegean we observe a clear difference between the thickly sedimented northern margin basins and the steep slopes of the trough margin of the southern north aegean the trough itself comprises a series of separate tectonic depressions resulting from an apparent transtensional motion the central aegean consists of a complex tectonic puzzle caused by the prevailing extension incipient strike slip faulting sub parallel to the north aegean trough trend may however affect its eastern anatolian domain three main structural areas characterize the southern aegean comparable structural directions cut across this chiefly extensional basin but one fault system may be prevailing over the others depending on the area the central cretan sea results from the interaction of at least two distinct extensions these were superimposed on previous mostly e w structural trends generated during the inception of the southern hellenic subduction and led to the present day predominant sw ne trending extension as a hypothesis we propose that the overall late miocene present evolution of the aegean sea is directly dependent on two geodynamic processes to the southeast of the area collision between arabia and turkey leads to the lateral westward expulsion of the aegean continental crust and to the west hellenic subduction is still active

two ship deep seismic soundings in the basins of the eastern mediterranean sea pasiphae cruise summary new results from a two ship refraction and oblique reflection deep seismic cruise are presented to discuss the nature of the crust in the ionian sirte and herodotus abyssal plains these expanding spread profiles were processed and analysed in both the x t and p domains arrival times of reflected and refracted branches are matched by ray tracing in both domains in spite of a shallow evaporitic sequence messinian evaporites deposited on top of a thick sedimentary pile responsible for velocity inversions on many profiles we obtain excellent velocity control down to moho depth pmp and pn 8 4 8 6 km s 1 arrivals are observed the three basins have a relatively thin crust 8 to 11 km overlain by a thick sedimentary cover up to 10km in the herodotus abyssal plain the moho boundary and main crustal units identified in the basins can be followed beneath the calabrian prism to the west and beneath the mediterranean ridge to the east the crustal structure is of oceanic type for both the ionian and sirte basins where typical oceanic layer 2 and 3 are recognized the thin crust of the herodotus basin may be interpreted either as oceanic or thinned continental crust about 10 km thick the top of the crust of the herodotus basin is much deeper therefore the herodotus basin is probably significantly older than the ionian basin triassic versus early cretaceous in age

multibeam bathymetric survey and high resolution seismic investigations on the barbados ridge complex eastern caribbean a key to the knowledge and interpretation of an accretionary wedge abstract an important problem of active margin processes is the way accretionary wedges form in response to oceanic crust subduction new data have been obtained along the barbados ridge in front of the lesser antilles tertiary island arc they include high resolution multichannel seismic data and accurate sea beam bathymetric maps both have been used to propose a 3 dimensional interpretation of tectonic and sedimentary processes related to subduction such as oceanic off scraping ductile folding relative uplift and subsidence fore arc basin evolution and mud diapirism they all improved our knowledge of the evolution of accretionary prisms and more specifically of the barbados ridge development in plio quaternary time previous tectonic events are deduced from recently published geological data from barbados and the lesser antilles islands

tertiary geodynamical evolution of northwestern greece paleomagnetic results abstract paleomagnetic results have been obtained from 29 sites sampled in lower to upper oligocene flysch sections of the ionian zone in northwestern greece they indicate a clockwise rotation of about 45 of the entire region a comparison with previously published results relative to both younger and older formations shows that this rotation has occurred in two phases of comparable amplitude one during middle miocene and the other during pliocene and quaternary separated by a period of at least 7 ma during which no significant rotation has occurred no major rotation has occurred during the entire paleocene and eocene stages this large measured rotation implies a horizontal displacement of at least 100 km in epirus possible mechanisms involving a rotation of the nappe sheets rotation of the basement or a combination of the two are discussed the two phases of paleomagnetic rotation can be correlated with the tertiary and quaternary calc alkaline volcanic activity in the aegean sea a palinspastic reconstruction shows that the orientation of the major structures now striking n155 was almost east west in the middle miocene at the epoch of their formation

evaluating the effect of plowing on the archaeological record the early middle palaeolithic in the river duero basin plateaus north central spain an abundant open air early middle palaeolithic record has been preserved in the duero basin plateaus castilla y leon region north central spain a long term landscape archaeology project has been underway in this area and since 1996 a number of studies have been carried out in order to evaluate the role played by post depositional factors in the refuse patterns observed the main post depositional disturbance forces are cultural ones and relate to the development of intensive mechanized agriculture the landscape project on the duero basin plateaus constitutes the first case in the iberian peninsula in which the effects of plowing have been monitored from a wide variety of approaches in a single area and on a long term basis at the same time this region offers a unique opportunity to evaluate the effect of plowing in palaeolithic spatial patterns this paper summarizes the main research lines on plowzone archaeology carried out between 1996 and 2007 within the landscape archaeology project undertaken in the palaeolithic sites of the duero plateaus and stresses the main assets of the archaeological record affected primarily by plowing

geological evidence for mud diapirism on the mediterranean ridge accretionary complex abstract a mud breccia has been repeatedly cored from four mud diapir fields located on the crest of the mediterranean ridge this breccia is composed of subrounded clasts supported by a clay rich matrix and ranges in age from cretaceous to early miocene sedimentological analysis allows identification of a primitive intrusive and a reworked mud breccia the latter being formed by mud extrusion and gravitational reworking of the former homogeneous mud sorted by grain size which occurs at the top of the diapirs has been interpreted as a lake deposit based on composition and carbon isotopic ratios gases present within the diapiric material suggest a partial thermogenic origin and gas escape structures have been identified in the mud breccia and host sediments carbonate crusts occurring in the host sediments are not related to bacterial oxidation of methane and consequent authigenic calcite precipitation their carbon and oxygen isotopic ratios reveal that they are characteristic of early deep sea lithification in the mediterranean sea the presence of a marker bed composed of mn nodules and bacterial colonies the mud lake deposits showing lower carbonate content than primitive mud breccia and the gas escape structures suggest the presence of active fluid vents in the vicinity of the diapiric structures evidence of active mud diapirism can be found from about 300 000 yrs b p to the present

modeling deformation and salt tectonics in the eastern mediterranean ridge accretionary wedge this study addresses some aspects of the kinematics and structural setting of the mediterranean ridge accretionary complex particularly those aspects related to the occurrence and distribution of messinian evaporites the approach is by 1 identification of the geometry of deformation through reprocessing of existing multichannel seismic reflection data from the levantine basin aimed at the definition of the velocity field and depth imaging 2 physical modeling in the laboratory aimed at the study of the kinematics of shortening of sedimentary sequences detaching on viscous decollements and 3 comparison between the results of the two approaches we conclude that the thick messinian sequence of the levantine basin is composed primarily of salt so that the entire evaporitic sequence can be expected to behave as a viscous material it follows that the main detachment of the post messinian wedge is located at the base of the messinian salt layer a viscous salt decollement would produce thrusting trending normal to the shortening direction but boundary conditions affect structural trends even more than stress and or movement direction both strain partitioning and the formation of major strike slip faults within the post messinian wedge are prevented by the high angle of convergence between the african and aegean plates as well as by the low intraplate friction in addition we show that curved and anastomosing thrust fronts are reflected in the cobblestone topography of the mediterranean ridge we finally postulate that extension may occur in the central mediterranean ridge as a result of the geometry of the plate boundaries this extension is considered as a possible cause of mud volcanism and mud diapirism

late miocene ductile extension and detachment faulting mykonos greece the geometry and style of structural relations at map to microscopic scale on mykonos cyclades aegean sea greece suggests ductile extension and detachment faulting during the late miocene this island is dominated by granitic rocks that have a well developed shallowly dipping mylonitic foliation and a northeast southwest trending mineral elongation lineation kinematic indicators in these rocks exhibit a top to the northeast down dip sense of shear textural relations suggest that conditions during mylonitic deformation were greenschist to amphibolite facies and published k ar geochronology suggests a late miocene age for this deformation event mylonitic rocks lie in the footwall of a low angle fault and fault striae parallel to the elongation lineation suggest kinematic coordination between mylonitic deformation and movement along the fault translation along the fault juxtaposes younger tilted sedimentary rocks of low metamorphic grade upon the once deeper mylonitic rocks the style and geometry of deformational fabrics and map relations on this island are strikingly similar to those observed in metamorphic core complexes of the western united states

geodetic determination of the kinematics of central greece with respect to europe implications for eastern mediterranean tectonics we use a new satellite laser ranging global positioning system slr gps solution at seven sites in anatolia and aegea to obtain a better definition of the extrusion motion of the anatolian aegean block with respect to europe we show that this motion can be described in a first approximation by a counterclockwise rotation which transfers most of the motion of arabia to anatolia we combine 78 displacement vectors obtained at common points of two triangulation nets measured in central greece in 1895 and 1975 with the slr gps measurements to compute the velocity field over greece with respect to europe these measurements indicate that central greece is a zone of extension between the anatolian aegean counterclockwise rotation to the south and the northern greece clockwise rotation to the north this extension is principally localized within the gulf of corinth to the east but is distributed to the west we then extrapolate this velocity field to the whole aegea and western anatolia using recently published gps results as well as the slr results the narrow dextral north anatolian fault which limits the velocity field to the north progressively gives way to a much wider boundary zone where extension becomes dominant we show that the collision between the mediterranean ridge and africa began 3 6 ma and we describe the modifications that this collision has produced on the kinematic pattern both in aegea and on the mediterranean ridge