geology and structure of the continental margin off northern israel and the adjacent part of the levantine basin abstract the continental margin off northern israel and southern lebanon is characterized by a narrow coastal plain in places it is absent a narrow shelf a narrow slope which is incised by numerous submarine canyons and by a complex topography of the adjacent deep sea levantine platform detailed seismic reflection surveys have revealed the development of the area since the late miocene during the messinian when the level of the mediterranean sea dropped the present continental slope area was exposed eroded and covered by thinly scattered sediments in the deep basin evaporite bearing series accumulated reaching 1 km in thickness about 60 km offshore during the pliocene quaternary the area was covered by a fine clastic sequence up to 1 5 km thick that forms the present continental margin basinward gravitational slumping of these sediments over the messinian evaporites which acted as a lubricant resulted in a complex topography and many shore parallel rootless growth faults along the base of the continental slope and the adjacent deep sea young faults which are exposed in northern israel and extend seaward comprise the most important structural feature of the study area these faults were active during the pliocene and quaternary possibly also during the miocene the major nw trending young yagur carmel fault and e w trending rosh hanniqra fault extend to the base of the continental slope where they converge enclosing the complex western galilee graben the relief of the base of the pliocene quaternary sequence was affected by motions of these faults and of smaller faults inside the graben farther seaward a horst like block is developed along the extension of the carmel fault still farther basinward there is a group of diapiric ridges trending nw to e w they were formed by flowage of messinian evaporites in some cases these ridges seem to be aligned along underlying faults this group of diapirs is unique in the area the diapir ridges are interpreted as expressions of deeply rooted faults

crustal shortening in the palmyride fold belt syria and implications for movement along the dead sea fault system an edited version of this paper was published in tectonics by the american geophysical union agu copyright 1990 agu see also http www agu org journals tc http atlas geo cornell edu syria chaimov tectonics 1990 html

seismic stratigraphic record of transpression and uplift on the romanche transform margin offshore ghana abstract recently available multi channel seismic reflection data from offshore ghana have been reprocessed to probe the eastern romanche fracture zone rfz of the equatorial atlantic and the sedimentary basins of the paleotransform margin the rfz terminates landward in a submarine canyon up to 2 km deep and 50 km wide variably filled with submarine fans and projects landward into a neoproterozoic dextral shear zone by contrast the rfz to the southwest is represented by an ene submarine escarpment juxtaposing continental and oceanic crusts three major sedimentary sequences representing pre syn and post rift strata have been identified from the seismic profiles and calibrated with chronostratigraphic data from oil exploration wells the pre rift sequence consists largely of paleozoic strata ranging in age from devonian to carboniferous the overlying syn rift sequence which was deposited during the intracontinental shearing stage consists of aptian to albian silicilastic strata with distinct continental facies the seismic sections provide some of the clearest images yet of i folding associated with transform displacement and ii southwest increasing subaerial erosion and stratal discordance we attribute lateral variation in erosion to crustal thickening associated with folding and to transient thermal effect of ridge transform interaction which is predicted to produce westward increasing uplift on this margin

environmental significance of bedrock jointing in southern ontario canada the bedrock surface of many glaciated areas is obscured by thick drift deposits in southern ontario canada the buried bedrock surface is dissected by channels infilled with glacial deposits as much as 150 m thick that are part of a wider mid continent preglacial fluvial system that predates formation of the modern great lake basins the infills of bedrock channels form major groundwater aquifers influence regional groundwater flows and contaminant migration to lake ontario and may localize the release of thermogenic methane and radon within heavily urbanized surface environments a quantitative comparison of the regional pattern of bedrock joints and the orientation pattern of buried bedrock channels and modern river valleys shows that all these orientation patterns are virtually coincident buried bedrock channels in south central ontario are not part of a simple antecedent drainage system but were likely predesigned by bedrock joint patterns that have subsequently been propagated upward into overlying pleistocene sediments joints in sediments are of considerable environmental significance for example subsurface contaminant and gas migration in fine grained clayey sediments and of many origins stress release desiccation etc but are widely assumed to be a predominantly surface related phenomena the existence of deeper joints has been noted by some authors but their origin is obscure data presented herein from south central ontario confirm that in addition to surface related joints a second population of bedrock related joints reflecting the upward propagation of bedrock fractures is present in pleistocene sediments of south central ontario

continental vs oceanic lithosphere beneath the eastern mediterranean sea implications from rayleigh wave dispersion measurements abstract tectonics of the eastern mediterranean are strongly influenced by subduction of oceanic lithosphere with slab pull as a prominent driving force the current distribution of remnants of oceanic lithosphere and the properties of african mantle lithosphere beneath the eastern mediterranean basin have been a matter of debate previous studies variously found continental as well as oceanic lithosphere in this region a set of 1 d s wave velocity models is determined in order to characterize the mantle lithosphere in the area between crete and the middle east for seven paths starting from cyprus and running to crete to anatolia as well as to the middle east broad band average phase velocity curves of the fundamental rayleigh mode are obtained in the frequency range of about 3 mhz to 90 mhz by a two station method in addition an east west oriented path crossing southern anatolia and a path running parallel to the dead sea fault zone are considered phase velocity curves are inverted for path average 1 d s wave velocity models resolution is investigated with the neighbourhood algorithm comparing the resulting 1 d models cold oceanic mantle lithosphere showing s wave velocities above 4 6 km s 1 can be distinguished from mantle lithosphere with low s wave velocities oceanic lithosphere is found west of cyprus beneath the herodotus basin as indicated by benioff zones it is subducting towards northwest in the southeastern aegean and towards northeast beneath southwestern anatolia to the east of cyprus the mantle lithosphere beneath the easternmost mediterranean sea shows low s wave velocities no indications for cold oceanic mantle lithosphere are found beneath the levant basin in the region of the dead sea fault zone and the levant basin the lithosphere asthenosphere boundary is located at shallow depths of about 60 km to 80 km the dsfz is situated in a region of thinned lithosphere underlain by an asthenosphere with anomalous low s wave velocities low s wave velocities beneath southern anatolia extend down to at least 150 km depth as expected for a back arc setting inferred moho depths vary for the different paths between 28 km and 41 km

three dimensional numerical simulation of the subduction dynamics in the sunda arc region southeast asia abstract the sunda arc has been modelled as a test subduction zone with geometrical complexities and varying dynamics we simulated spatially the structural heterogeneities of the subduction zone and carried out our computations by a three dimensional finite element approach the aim is to estimate the lateral variation in the effective horizontal compressive stress in the interplate region which can produce the present day observed seismogenic stress field in our simplified approach the stress field has been modelled by varying the traction ridge push while keeping the age dependent gravitational body force slab pull constant our result suggests that there is a considerable amount of stress dissipation in the decoupled segment of java at sumatra the required traction is much greater than that expected from the age dependency relations in our modelling the transition from the dominance of the horizontal compressive stress to that of the gravitational pull in the regional stress field occurs around a depth range of 150 200 km lateral variation in the subducted slab volume emerges crucial to the seismogenic stress field and the derived pattern of displacement subduction of the lighter oceanic rise material should enhance the stress level the effect of abrupt lateral variation in structure e g sudden changes in the slab dip or slab depth may also be significant on the regional stress field viscoelastic modelling attempted for estimating the temporal variation in subduction dynamics suggests that the thrust level will increase southward of the present day thrust zone in java while strike slip fault type stress field will be developed south of sumatra

shear wave polarization anisotropy and subduction induced flow in the mantle wedge of northeastern japan abstract shear wave polarization anisotropy in the central part of northeastern ne japan was investigated we analyzed s phases of 293 intermediate depth earthquakes recorded at 77 stations and obtained 1286 splitting parameters the obtained results show the systematic variation in splitting parameters across the arc the leading shear wave polarization directions fast direction obtained at stations in the western side of the study area are oriented nearly e w which is sub parallel to the direction of relative plate motion between the pacific plate and the north american okhotsk plate in contrast fast directions obtained at stations in the eastern side of the study area are oriented approximately n s stations in the western side have a larger average delay time compared to those in the eastern side these variations suggest that the nature of anisotropy is quite different between the eastern and the western sides both experimental studies on the deformation of olivine and numerical simulations of plate driven flow predict that the lattice preferred orientation of olivine causes the fast direction sub parallel to the flow direction for the conditions in the mantle wedge of ne japan we thus infer that the lattice preferred orientation of olivine generated by flow induced strain is the most likely candidate for anisotropy that produces splitting with e w fast direction three possible causes of anisotropy in the eastern side are considered deformation of water rich olivine in the mantle wedge trench parallel flow in the mantle wedge due to along strike dip variations in the slab and anisotropy in the crust and the slab we could not however determine which causes are dominant further systematic study is required to reveal the cause of anisotropy in the eastern side

structural implications of strain localization towards a continental transform fault the example of the shift between the levant margin and the dead sea fault plate boundary abstract continental transform faults accommodate lateral motion between two adjacent plates often evidence for such motion is hard to detect due to onland processes of erosion investigation of a submerged passive continental margin adjacent to a transform plate boundary might provide indications for the developmental stages of the transform to examine this hypothesis we analyzed the messinian to recent stratigraphy and structure of the levant continental margin that resides ca 100 km from the dead sea fault dsf continental transform the analysis is based on interpretation of seismic reflection data 2d and 3d time migrated and pre stack 3d depth migrated and four boreholes it includes construction of structural maps tracking of stacking patterns and calculations of sedimentation rates data show that the levant margin developed through three phases 1 late miocene earliest zanclean 6 5 ma nne ssw left lateral strike slip faulting 2 zanclean late gelasian 5 1 8 ma syn depositional folding striking in the same direction the top gelasian surface marks an abrupt change which is expressed as 3 mass slumping that occurred due to regional basinward tilt continuation of differential subsidence is manifested by calabrian to recent progradation 1 8 0 ma while nile sediment flux peaked at 1 8 ma and decreased during the calabrian to recent our data shows an increase in sedimentation on the levant margin throughout the entire plio pleistocene this discrepancy is caused by the regional tilting of phase 3 which shifted the depocenter to the west correlations to onshore findings suggest that the faulting folding and tilting observed on the continental margin represent localization of strain towards the dsf during the pliocene gelasian 5 3 1 8 ma this is attributed to the consequent deepening of the dsf and the incipient collision of the eratosthenes seamount with the cyprus arc the continental margin records the development of the nearby active transform through structural and sedimentary modifications

the migration history of the nazca ridge along the peruvian active margin a re evaluation abstract the collision zone of the 200 km wide and 1 5 km high nazca ridge and the peruvian segment of the convergent south american margin between 14 s and 17 s is characterized by deformation of the upper plate and several hundred meters of uplift of the forearc this is evident by a narrowing of the shelf a westward shift of the coastline and the presence of marine terraces as the nazca ridge is oblique with respect to both trench and convergence direction of the nazca plate it migrates southward along the active plate boundary for reconstructing the migration history of the nazca ridge this study uses updated plate motion data resulting from a revision of the geomagnetic time scale the new model suggests that the ridge crest moved laterally parallel to the margin at a decreasing velocity of 75 mm a before 10 8 ma 61 mm a 10 8 4 9 ma and 43 mm a 4 9 ma to present intra plate deformation associated with mountain building in the peruvian andes since the miocene reduces the relative convergence rate between nazca plate and peruvian forearc taking an intra plate deformation at a rate of 10 mm a estimated from space geodetic and geological data into account does not significantly reduce these lateral migration velocities constraining the length of the original nazca ridge by its conjugate feature on the pacific plate yields a length of 900 km for the subducted portion of the ridge using this constraint ridge subduction began 11 2 ma ago at 11 s therefore the nazca ridge did not affect the northern sites of ocean drilling program odp leg 112 located at 9 s this is supported by benthic foraminiferal assemblages in odp leg 112 cores indicating more than 1000 m of subsidence since at least middle miocene time and by continuous shale deposition on the shelf from 18 to 7 ma recorded in the ballena industrial well at 11 5 s the model predicts the passage of the ridge crest 9 5 ma ago this agrees with the sedimentary facies and benthic foraminiferal stratigraphy of odp leg 112 cores which argue for deposition on the shelf in the middle and late miocene with subsequent subsidence of a minimum of several hundred meters onshore at 12 s the sedimentary record shows at least 500 m uplift prior to the end of the miocene also in agreement with the model

new regional gravity and magnetic maps of the levant a new compilation of regional gravity and magnetic maps of the levant based on detailed local maps and data bases for various parts of the region is presented the most apparent feature of the levant gravity map is the regional high associated with the mediterranean basin high values extend eastward on land to the dead sea rift dsr suggesting a relatively thin basic crust under northern israel and lebanon the magnetic pattern offers additional evidence on the transform nature of the dsr it also suggests that the gulf of suez is associated with an arcuate lineament which extends in a nne direction deep into the mediterranean sea possibly up to the cyprean arc this apparent lineament may indicate an ancient shear zone

response of the mantle to flat slab evolution insights from local s splitting beneath peru the dynamics of flat subduction particularly the interaction between a flat slab and the overriding plate are poorly understood here we study the seismically anisotropic properties and deformational regime of the mantle directly above the peruvian flat slab we analyze shear wave splitting from 370 local s events at 49 stations across southern peru we find that the mantle above the flat slab appears to be anisotropic with modest average delay times 0 28 s that are consistent with 4 anisotropy in a 30 km thick mantle layer the most likely mechanism is the lattice preferred orientation of olivine which suggests that the observed splitting pattern preserves information about the mantle deformation we observe a pronounced change in anisotropy along strike with predominately trench parallel fast directions in the north and more variable orientations in the south which we attribute to the ongoing migration of the nazca ridge through the flat slab system

stratigraphic evidence for shear in structural development of the triassic levant margin new borehole data on the epicontinental to deep marine transition in israel abstract triassic tectonic movements that include shear along a significant portion of the levant margin are evidenced from microfacies analysis of material recovered from the asher atlit 1 ga ash 2 meged 2 devora 2 and ramalla 1 onshore boreholes seismic studies showed that structural lineaments attributed to early mesozoic extension underlie coastal and central israel trending ne sw beneath southern israel and sub parallel to the then extensional palmyride basin of syria a more curved trend approximately nnw sse lies to the north beneath central israel coast parallel sedimentary domains formed above these lineaments which constitute the newly formed passive margin of the levant coast in the triassic the sedimentary history of these domains indicates that some were linked to each other and others disconnected the relative vertical movement between one domain and another is explained by activation of transpressional and trans tensional shear movements on the underlying curved faults these subordinate vertical movements also created the discontinuous barriers and small subsiding basins that separate the epicontinental sedimentary domain from the open tethys causing partial restriction necessary for the intermittent development of thick evaporites in the internal domains alternating with a regionally suppressed carbonate system this zone is here named the onshore levant margin shear zone olmsz shear was invoked theoretically in a number of models for the tectonic evolution of the eastern mediterranean as part of a neotethyan opening system this paper provides rock based evidence for such shear applicable to 20 of the eastern levant margin in the triassic

the structural evolution of the messinian evaporites in the levantine basin abstract the levantine basin in the south eastern mediterranean sea is a world class site for studying the initial stages of salt tectonics driven by differential sediment load because the messinian evaporites are comparatively young the sediment load varies along the basin margin they are hardly tectonically overprinted and the geometry of the basin and the overburden is well defined in this study we analyse depositional phases of the evaporites and their structural evolution by means of high resolution multi channel seismic data the basinal evaporites have a maximum thickness of about 2 km precipitated during the messinian salinity crisis 5 3 5 9 ma ago the evaporite body is characterized by 5 transparent layers sequenced by four internal reflections we suggest that each of the internal reflection bands indicate a change of evaporite facies possibly interbedded clastic sediments which were deposited during temporal sea level rises all of these internal reflections are differently folded and distorted proving that the deformation was syn depositional thrust angles up to 14 are observed backstripping of the pliocene quaternary reveals that salt tectonic is mainly driven by the sediment load of the nile cone the direction of lateral salt displacement is mainly ssw nne and parallel to the bathymetric trend apparent rollback anticlines off israel result rather from differential subsidence than from lateral salt displacement in the south eastern basin margin the deposition of the isreali slump complex isc is coeval with the onset of salt tectonic faulting suggesting a causal link between slumping processes and salt tectonics the superposition of thin skinned tectonics and thick skinned tectonics becomes apparent in several locations the fold belt off the israeli mediterranean slope mainly results from active strike slip tectonics which becomes evident in faults which reach from the seafloor well below the base of the evaporites owing to the wrenching of the crustal segments which are bounded by deep rooted fault lines like the damietta latakia pelusium and shelf edge hinge line the setting is transpressional south of 32 n where the fault lines bend further towards the west this adds a component of thick skinned transpression to the generally thin skinned compressional regime in the basin above 1 5 km of evaporites a mud volcano is observed with the mud source seemingly within the evaporite layer at the eastern cyprus arc the convergence zone of the african and the anatolian plates deep rooted compression heavily deformed the base of the evaporites whereas at the eratosthenes seamount mainly superficial compression affecting the post messinian sediments and the top of the evaporites is observed

seismotectonics of the sinai subplate the eastern mediterranean region summary we define the sinai subplate from a seismotectonic perspective as a distinct component in the plate tectonics of the eastern mediterranean region this is based on the tectonic characteristics of a comprehensive listing of all ml 4 recorded seismicity in the region during the 20th century on newly calculated and recalculated fault plane mechanisms of first p wave arrivals and on published solutions based on waveform inversion of broad band data the low seismicity level and scarcity of strong events in the region required a thorough search for useful data and a careful examination of the reliability of the focal solutions we gathered all available records of first p wave onsets from the iss and isc bulletins and the local seismic networks altogether we were able to calculate 48 new focal mechanisms and 33 recalculated ones of events that occurred during the years 1940 1992 with the increasing number of teleseismic and regional broad band stations in the later years we added 37 solutions based on teleseismic and regional waveform inversions of events that occurred during 1977 2001 these mechanisms enabled us to examine the seismotectonic character of the sinai subplate the strike and rake directions of the calculated mechanisms usually reflect the geometry and the large scale type of deformation observed along the boundaries of the sinai subplate the dead sea transform the cypriot arc convergent zone and the suez rift nevertheless along each of these boundaries we found anomalous solutions that attest to the complexity of the deformation processes along plate margins earthquakes along the dead sea transform exhibit mainly sinistral transtension and transpression reflecting its leaky manner and local change in the transform geometry the presence of other unexpected mechanisms near the transform however reflects the heterogeneous deformation it induces around as expected thrust mechanisms along the cypriot arc mirror its convergent nature and typical curved geometry transtension and transpressional solutions in the eastern segment of the arc reflect the sinistral shear motion between anatolia and sinai there however shear mechanisms found between cyprus and the eratosthenes seamount pose a problem regarding its collision process most intriguing of all are ml 4 thrust and shear solutions found in the gulf of suez they are associated with predominantly normal mechanisms within a rift zone and therefore constitute a unique phenomenon yet to be deciphered

sediment transport mechanisms revealed by quantitative analyses of seafloor morphology new evidence from multibeam bathymetry of the israel exclusive economic zone abstract this study synthesizes 15 years 2001 2016 of detailed multibeam hydrographic mapping covering the entire 26 500 km2 of the israeli exclusive economic zone eez multibeam data were collected on board three research vessels across the continental shelf slope and the deep levant basin between water depths of about 15 m to 2100 m single channel 3 5 khz seismic reflection chirp profiles were collected simultaneously with the multibeam surveys in selected parts of the area the new data enabled the first comprehensive quantitative seafloor morphological analysis of the slope and deep basin using gis techniques on the high resolution multibeam data we analyze the spatial distribution and quantitatively describe the seafloor morphologies in detail high resolution chirp seismic profiles demonstrate the underlying shallow structure results indicate that the seabed comprises five main morphologies folds faults sediment waves deepwater channels and sediment fan lobes quantitative morphological analysis and seismic data interpretation were used to derive field relations between these morphologies which along with previously collected multi channel seismic reflection data suggest that a concentric fold geometry formed around the nile outlet during the late pliocene to early pleistocene as part of a general thin skin radial salt tectonic deformation above the messinian mobile unit this radial motion was accompanied by displacement along nne trending strike slip faults in the basin and an extensional component across e w trending strike slip faults along the levant margin while some of these displacements continue to deform the modern seabed across area a others are covered by a wedge of quaternary deposits mainly in the northeastern part of the basin area b areas a and b also differ in grain size distribution as indicated by backscatter analysis of the multibeam data these observations divide the israeli eez into two distinct areas area a nile derived siliciclastic sediments transported directly into the deep basin via confined forming meandering channels and overbank deposits and unconfined flows forming fans and lobes the wedge consisting of area b was fed by erosion products of the nile outlet that were transported northwards along the continental shelf by seafloor currents of the levant jet system and glided down the northern levant continental slope as turbidity currents this supply built at least seven sequences of quaternary sediment waves that form upslope migrating cyclic steps the complete data coverage and quantitative morphological analysis presented here introduce new spatial and temporal constraints that call for a reexamination of previous seabed sampling locations not accounting for detailed bathymetry and to augment future seabed sampling efforts understanding the sediment supply paths across the basin and the geomorphological footprint of salt tectonics processes

tectonic processes in offshore northern israel and the evolution of the carmel structure abstract the carmel structure in northern israel is an elevated tilted block that extends from the land into the continental shelf and divides the levant continental margin into two distinct provinces its axis trends at a high angle to the levant margin and deflects mesozoic and cenozoic sedimentary and basement rocks the carmel structure is probably older than the levant margin itself and has been through several phases of activity most of the multichannel seismic profiles in the offshore of northern israel were reprocessed through time migration and then interpreted the resultant maps combined with gravimetric magnetic and bathymetric maps show a complex tectonic picture of the carmel structure and its vicinity four evolutionary stages can be recognized in this area a early mesozoic rifting along the present levant margin we speculate that the carmel was at that time a triple junction a thick mesozoic volcanic and carbonatic section of more than 6500 m indicates rapid subsidence probably accompanied by normal faulting b folding along the nne axis this is probably part of the syrian arc compressional system which was active from the late cretaceous until the eocene normal faults of the previous stage were probably reactivated becoming reverse faults c left lateral strike slips faulting this formed a north west fault system which resulted in a clockwise rotation of segments of the fold axis and was active from the late miocene to early pliocene d a tensional tectonic regime prevails since the pliocene and is probably still active at present the well pronounced kishon graben which extends from land to the continental shelf was formed during this period the first two stages are of regional extent whereas the latter stages are the reslt of local modification of the regional stress fields

morphological and structural relations in the galilee extensional domain northern israel the lower galilee and the yizre el valley northern israel are an extensional domain that has been developing since the miocene prior and contemporaneously to the development of the dead sea fault dsf it is a fan shaped region bounded in the east by the n s trending main trace of the dsf in the north by the bet kerem fault system and in the south by the nw se trending carmel fault the study area is characterized by high relief topography that follows fault bounded blocks and flexures at a wavelength of tens of km a synthesis of the morphologic structural relations across the entire galilee region suggests the following characteristics 1 blocks within the lower galilee tilt toward both the southern and northern boundaries forming two asymmetrical half graben structures opposite facing and oblique to one another 2 the lower galilee s neighboring blocks which are the upper galilee in the north and the carmel block in the southwest are topographically and structurally uplifted and tilted away from the lower galilee 3 the southern half graben along the carmel fault is topographically and structurally lower than the northern one combining structural and geological data with topographic analysis enables us to distinguish several stages of structural and morphological development in the region using a semi quantitative evolutionary model we explain the morpho structural evolution of the region our results indicate that the galilee developed as a set of two isostatically supported opposite facing half grabens under varying stress fields the southern one had started developing as early as the early miocene prior to the formation of the dsf the northern and younger one has been developing since the middle pliocene as part of the extension process in the galilee elevation differences between the two half grabens and their bounding blocks are explained by differences in isostatic subsidence due to sedimentary loading and uplift of the northern half graben due to differential influences of the regional folding d 2003 elsevier b v all rights reserved

what can a sessile mollusk tell about neotectonics article i nfo dendropoma petraeum are fixed vermitids mollusk that colonize and construct abrasion platform rims along rocky shorelines these endemic mollusks are considered good relative sea level indicators in the eastern and the southern mediterranean due to their narrow habitat below the sea surface about 10 cm the observed relative sea level values recorded submerged uplifted or at present mean sea level reflect a superposition of eustatic isostatic tectonic and possibly local sedimentary instabilities the present study examines fossil dendropoma samples gathered along the levant coast from northern israel to eastern turkey conventional radiocarbon dates from turkey syria and partly in lebanon and 14 c accelerator mass spectrometer ams from lebanon and israel yields dendropoma ages ranging through late holocene a numerical model is used for calculating the change in sea level through the holocene as a function of glacio hydrology and isostasy of the eastern mediterranean space time dependent subtractions of the model values are used to eliminate the eustatic component of the relative sea level in order to obtain the tectonic component results show a general northward increase in tectonic uplift of the levantine coast with different rates in different tectonic segments this differential uplift corresponds well to the major tectonic segments comprising the levantine continental margin since the pleistocene from the carmel fault to the east anatolian fault hence these segments were still active during the last thousands years and even during the last hundreds years the general trend of northward increase in vertical displacement is predominantly dictated by the convergence between the sinai and arabian plates with anatolia and eurasia across the cyprus arc and zagros belt and the secondarily dictated by the northward increase in convergence component across the sinistral dead sea fault plate boundary

internal structure of the dead sea leaky transform rift in relation to plate kinematics abstract the structures along the dead sea transform rift are related to the motions of the sinai and arabia plates which border it and to the irregularities of their boundaries the total slip was 105 km left lateral but the present structures were formed mainly during the last 40 km of slip which probably occurred in the plio pleistocene along the southern half of the transform the strike slip motion takes place on en echelon faults this produces rhomb shaped grabens or pull aparts which are sometimes composite and in which there is local crustal separation thus much of the transform is leaky these structures occur in a morpho tectonic rift valley delimited by normal faults which express a small component of transverse extension along a few segments the shape of the transform is such that lateral motion produces local transverse compression the geometric relations of the structures along the transform define an eulerian pole of relative plate motions at 32 8 n 22 6 e 0 5 the older motion was somewhat different and is described by a pole located about 5 west of the above then the component of transverse extension and crustal separation was much smaller than now while local transverse compression was more important the northern half of the dead sea transform has an irregular shape and the bordering plates did not remain rigid as lateral motion continued here transverse compression is often important

intraplate deformation by block rotation and mesostructures along the dead sea transform northern israel combined analysis of mega and meso structures yield the strain inferred stress and tectonic history of the margin of the sinai sub plate in northern israel along the dead sea transform three major stress regimes were developed and have affected the region since the middle miocene one is regional and controlled the left lateral shear along the dead sea transform this one has been active since post early miocene is characterized by 1 trending c 345 and deformed the plate margin by horizontal shear and contemporaneous block rotation this style of deformation is similar to simple shear the second one was local and may be subdivided into distinct stress and strain domains it was characterized by 1 trending e w and 3 trending n s which produced a conjugate set of strike slip faults the region underwent n s elongation by horizontal shear and block rotation similar to the pure shear mechanism this stress regime was active in late miocene to early pliocene time the third and youngest stress regime is extentional with 1 vertical and 3 oriented n s this one has been active since post middle pliocene time producing e w normal faults and minor n s elongation the second and third stress regimes show local distribution and developed as a consequence of the bent geometry of the transform vis a vis the plate slip vector finite element and photoelastic models predict the development of local stress fields and elongation of the plate margin parallel and subparallel to the transform plate boundary the strain of the plate margin in northern israel and southern lebanon indicate remarkable elongation parallel to the dead sea transform by a factor of 1 5 2 1 since the miocene this process of intraplate deformation and the consequent strain is unique to the parts of the plate margin which are adjacent to the bent segment of the transform

seismicity of the eastern mediterranean region perspective from the sinai subplate we conducted a comprehensive study of the seismicity of the eastern mediterranean and examined its relation to the regional plate tectonics based on various published catalogs we have constructed a new list of ml 4 earthquakes which were recorded during the years 1900 1991 and represents most of the seismic moment released in the area over this period b values are 1 02 1 0 and 1 07 for the whole sinai subplate the dead sea transform and the cypriot arc respectively seismic efficiency of the dead sea transform is very low about 7 stressing the role of aseismic deformation in that plate border most of the major and moderate events ml 5 occur in belts associated with the geologically documented borders of the sinai subplate the cypriot convergent arc in the north the dead sea transform in the east and the rift of suez in the southwest the latter like the gulf of eilat aqaba was considered aseismic during the first half of the century the northwestern border however could not be delineated low level activity appears within the subplate especially north of latitude 32 n reflecting the breakdown of this part of sinai as it approaches the cypriot convergence zone though most of the seismic moments tend to concentrate along the subplate borders some moderate activity spreads out in wide belts which reflect the complexity of deformation accompanying motion along the subplate borders

transcurrent fault activity on the dead sea transform in lebanon and its implications for plate tectonics and seismic hazard fault activity within the lebanese transpression zone one of the classic examples of restraining bend development on a continental transform is here investigated using dated geomorphological features the northern part of the yammouneh fault commonly considered to be the principal active strand on this part of the dead sea transform has been inactive for the past 5 ma field observations show that basalts dated as late pliocene hi age apparently offset by the yammouneh fault unconformably overlie it the active transcurrent structure is principally perhaps exclusively the roum fault the lebanese transpressive zone has evolved through tune with migration of fault activity these results confirm the overlapping transform hypothesis for the dead sea system require the active triple junction between the transform and the tethyan collision belt to lie offshore se cyprus and have profound implications for assessing seismic hazard hi the levant

moho map of south america from receiver functions and surface waves 1 we estimate crustal structure and thickness of south america north of roughly 40 s to this end we analyzed receiver functions from 20 relatively new temporary broadband seismic stations deployed across eastern brazil in the analysis we include teleseismic and some regional events particularly for stations that recorded few suitable earthquakes we first estimate crustal thickness and average poisson s ratio using two different stacking methods we then combine the new crustal constraints with results from previous receiver function studies to interpolate the crustal thickness between the station locations we jointly invert these moho point constraints rayleigh wave group velocities and regional s and rayleigh waveforms for a continuous map of moho depth the new tomographic moho map suggests that moho depth and moho relief vary slightly with age within the precambrian crust whether or not a positive correlation between crustal thickness and geologic age is derived from the pre interpolation point constraints depends strongly on the selected subset of receiver functions this implies that using only pre interpolation point constraints receiver functions inadequately samples the spatial variation in geologic age the new moho map also reveals an anomalously deep moho beneath the oldest core of the amazonian craton

multiphase reverse vertical tectonic displacement across major faults in northern israel abstract geological investigations in northern israel supported by recent seismic interpretation of offshore data indicate that the major fault systems there have undergone several tectonic phases since the mesozoic it is suggested that the vertical displacements related to the younger phase of neogene to recent age are in a reverse direction to those of the mesozoic and older phases

effect of water and stress on the lattice preferred orientation of olivine the influence of water and stress on the lattice preferred orientation lpo of olivine aggregates was investigated through large strain shear deformation experiments at high pressures and temperatures p 0 5 2 1 gpa t 1470 1570 k under both waterpoor and water rich conditions the specimens are hot pressed synthetic olivine aggregates or single crystals of olivine water was supplied to the sample by decomposition of a mixture of talc and brucite deformation experiments were conducted up to shear strain 6 using the griggs apparatus where water fugacity was up to 13 gpa at the pressure of 2 gpa the water content in olivine saturated with water increases with increasing pressure and the solubility of water in olivine at p 0 5 2 gpa was 400 1200 ppm h si several new types of lpo in olivine are found depending on water content and stress samples deformed in waterpoor conditions show a conventional lpo of olivine where the olivine 100 axis is subparallel to the shear direction the 010 plane subparallel to the shear plane type a however we identified three new types type b c and e of lpo of olivine depending on the water content and stress the type b lpo of olivine which was found at relatively high stress and or under moderate to high water content conditions is characterized by the olivine 001 axis subparallel to the shear direction the 010 plane subparallel to the shear plane the type c lpo which was found at low stress and under water rich conditions is characterized by the olivine 001 axis subparallel to the shear direction the 100 plane subparallel to the shear plane the type e lpo which was found under low stress and moderate water content is characterized by the olivine 100 axis subparallel to the shear direction the 001 plane subparallel to the shear plane observations by transmission electron microscopy tem and scanning electron microscopy sem show that the dislocations in water poor samples type a are curved and both b 100 and b 001 dislocations have a similar population numerous subgrains are seen in water poor samples in backscattered electron images in contrast water rich samples both type b and type c contain mostly b 001 dislocations and dislocations are straight and sub grain boundaries are rare compared to those in water poor samples these observations suggest that 1 dominant slip systems in olivine change with water fugacity and stress and 2 grain boundary migration is enhanced in the presence of water seismic anisotropy corresponding to the fabrics under water rich condition is significantly different from that under water poor condition consequently the relationship between seismic anisotropy and flow geometry in water rich regions is expected to be

flip convergence across the phoenician basin through nucleation of subduction abstract modern examples of active subduction nucleation are scarce hence knowledge is derived from reconstructions of old subduction zones and numerical modeling here we present a rare analog of induced subduction nucleation occurring today along the northeastern mediterranean continental margin geological evidence gathered here suggests that plate convergence between africa sinai arabia and eurasia anatolia since the pliocene led to fragmentation of the northern sinai plate into the phoenician and northern levant micro plates currently convergence is in the process of shifting from subduction cessation beneath the eastern cyprus arc to reactivation of the northern levant margin this shift induces the nucleation of an embryonic subduction zone through polarity reversal it re defines the front of plate convergence

tectono stratigraphic evolution of the western margin of the levant basin offshore cyprus abstract stratigraphic interpretation of twenty four 2d seismic reflection profiles coupled with available well data from the ocean drilling program odp offshore cyprus enabled identification of the main unconformities and the seismic packages in the western part of the levant basin and their correlation with major geodynamic events the basic concepts of seismic stratigraphy were applied to improve our understanding of the tectonostratigraphy and the sedimentary architecture of eratosthenes isolated carbonate platform this platform is composed of dominant retrograding and aggrading mesozoic carbonate build ups and its evolution partly resembles that of the egyptian margin deep water mixed carbonates and siliciclastics probably prevailed in the basin during the early cretaceous during the late cretaceous these platforms were drowned following the convergence of the two plates both the eratosthenes seamount esm area and the levant basin progressively became part of a foreland basin along the cyprus arc different units in the eratosthenes carbonate platforms ecps and the transition to the deep levant basin are detailed here for the first time we present a 3d conceptual model for the evolution of the western margin of the levant basin we discuss the effect of the miocene collision between the cyprus arc and eratosthenes to understand the presence of upper miocene mass transport complexes mtcs in the deep basin and the tilting of the top of the adjacent ecps we briefly examine the deformation mechanisms of the messinian salt near the paleo shelves of the ecps

seismic evidence for neogene and active shortening offshore of lebanon shalimar cruise 1 lebanon located on a 160 km long transpressional bend of the left lateral levant dead sea fault system lfs has been the site of infrequent but large earthquakes including one submarine tsunamigenic event the main objective of the shalimar marine survey was to characterize and map active deformation offshore of lebanon using a range of geophysical techniques particularly seismic reflection profiling the cruise results clearly establish the presence of young submarine thrust faults and folds and clarify the structure of this part of the levant margin a submarine fold belt bounded by thrusts and lateral ramps and extending up to 30 km from the shoreline is interpreted as the foreland thrust system of the actively growing mount lebanon range there is no large fault extending into the levant basin toward cyprus which indicates that thrusting only absorbs local transpression resulting from the lebanese restraining bend both the miocene and plio quaternary sedimentary sequences are affected by shortening with landward dipping blind thrusts and associated growth strata the presence of the messinian evaporites creates complex deformation patterns including normal faults due both to folding accommodation and to gravity spreading all well imaged in the seismic reflection profiles because the evaporite layer acts as a decollement level shortening extends farther out seaward through a series of thrust imbricates or duplexes the strongest shortening observed between beirut and batroun decreases toward the south between saida and tyre north of tripoli the passive margin is not affected by neogene deformation and is well preserved we propose that since the miocene the northward propagating lfs interacted with margin structures inherited from the mesozoic rifting phase and was deviated along the more rigid oceanic crust flooring the levant basin a process which led to the formation of the lebanese restraining bend of the lfs and consequently to the offshore shortening we document here such coastal transpression has resulted in local 100 km inversion of the passive margin which might eventually evolve into a new subduction zone

bedrock jointing and geomorphology in southwestern ontario canada an example of tectonic predesign in southwestern ontario canada palaeozoic sedimentary strata are covered by pleistocene glacial sediments the topography of the buried bedrock surface has been mapped over an area of some 45 000 km2 using new computerised depth to bedrock data from more than 200 000 waterwells this information shows that arching of the underlying proterozoic basement canadian shield and differential erosion of carbonate and shale strata are first order regional controls on bedrock geomorphology these data also define a network of buried bedrock channels quantitative analysis of the trends of these channels reveals a statistical correspondence between channel orientation and regional bedrock joint sets formed in response to the mid continent stress field the orientations of bedrock channels and joints correspond regionally with mean trends at 153 and 164 respectively in addition two dominant orientations of postglacial river valleys and bedrock joints correspond with mean trends at 104 vs 104 and 54 vs 52 respectively our findings show that the erosional channelled topography cut on bedrock together with the postglacial drainage pattern cut into younger glacial sediments are related to the trend of bedrock joints and consequently can be described as tectonically predesigned in addition this study yields new insights into the form of the preglacial tertiary drainage system in southern ontario prior to pleistocene glaciation regardless of the precise age of this preglacial system and degree of subsequent glacial modification an important factor in its geomorphic development has been the mid continent stress field

orthogonal joint systems in the bergen area southwest norway and their regional significance abstract joint orientation measurements are reported from the bergen district southwest norway the prevailing joint systems form two near vertical near orthogonal sets striking preferentially nw se and ne sw the orientation of these fissure systems is consistent with fissure systems dissecting the surface formations precambrian to quaternary throughout britain and northwest france they also show general agreement with lineaments in southern norway as revealed by landsat imagery it is suggested that the orthogonal joint network represents a fundamental tectonic structure originally implanted into the mobile outer layer of the earth in precambrian time the network has been repeatedly reactivated throughout the earth s dynamic tectonic history it was probably formed in a shear regime caused by torsional deformation associated with rotation of large scale lithospheric units which is still operating today

coseismic displacements along the serghaya fault an active branch of the dead sea fault system in syria and lebanon examination of the serghaya fault a branch of the dead sea fault system in western syria and eastern lebanon documents late quaternary and recent left lateral fault movements including the probable remnant of a historic coseismic surface rupture carbon 14 dating and the presence of fault scarp free faces in soft late pleistocene lake deposits suggest coseismic slip during the past two or three centuries possibly corresponding with one of the well documented earthquakes of 1705 or 1759 with an estimated holocene slip rate of 1 2 mm a 1 the serghaya fault accommodates a significant part of the active deformation along the arabian african plate boundary these results suggest that multiple active fault branches are involved in the transfer of strain through the lebanese restraining bend

fault controlled evaporite deformation in the levant basin eastern mediterranean abstract during the messinian salinity crisis a multi layered salt giant of 1 5 km thickness was precipitated in the levant basin easternmost mediterranean sea incipient deformation of this geologically young salt layer was commonly explained by gravity driven processes only based on high quality depth migrated seismic data we show for the first time how sub salt extensional faults influence the internal deformation pattern of the messinian evaporites in the levant basin extensional faulting started in the middle miocene and lasted until late messinian times we suggest faulting to have caused the development of fault propagation folds within the evaporite unit subsequently folds may have accommodated tectonic shortening at the latakia ridge and evolved into the presently observed complex intra evaporite fold pattern while fault controlled evaporite deformation is evident in the northern part of the levant basin only evaporites are increasingly influenced by nile derived differential sediment loading towards the south locally zones of reduced amplitudes in the sub salt domain terminate into phase reversed bright spots within the lower part of the evaporites indicating active fluid migration and potentially evaporite dissolution finally we present a high resolution velocity model of the messinian evaporites based on model based processing and residual moveout analysis relatively high interval velocities of acoustically transparent evaporites 3850 4240 km s are consistent with halite whereas lower velocities of reflective layers 3650 4030 km s may point towards the presence of low velocity evaporite facies like gypsum

the messinian salinity crisis past and future of a great challenge for marine sciences forty years after the image of the mediterranean transformed into a giant salty lake was first conceived the fascinating history of the messinian salinity crisis msc still arouses great interest across a large and diverse scientific community early outcrop studies which identified severe palaeoenvironmental changes affecting the circum mediterranean at the end of the miocene were followed by investigations of the marine geology during the 1950s to 1970s these were fundamental to understanding the true scale and importance of the messinian event now after a long period of debate over several entrenched but largely untested hypotheses a unifying stratigraphic framework of msc events has been constructed this scenario is derived mainly from onshore data and observations but incorporates different perspectives for the offshore and provides hypotheses that can be tested by drilling the deep mediterranean basins the msc was an ecological crisis induced by a powerful combination of geodynamic and climatic drivers which had a great impact on the subsequent geological history of the mediterranean area and on the salinity of the global oceans these changed the mediterranean s connections with both the atlantic ocean and the freshwater paratethyan basins causing high amplitude fluctuations in the hydrology of the mediterranean the msc developed in three main stages each of them characterized by different palaeoenvironmental conditions during the first stage evaporites precipitated in shallow sub basins the msc peaked in the second stage when evaporite precipitation shifted to the deepest depocentres and the third stage was characterized by large scale environmental fluctuations in a mediterranean transformed into a brackish water lake the very high resolution timescale available for some late miocene intervals in the mediterranean makes it possible to consider environmental variability on extremely short time scales including in some places annual changes despite this fundamental questions remain some of which could be answered through new cores from the deepest mediterranean basins improvements in seismic imaging and drilling techniques over the last few decades make it possible to plan to core the entire basinal messinian succession for the first time the resulting data would allow us to decipher the causes of this extreme environmental change and its global scale consequences

joints as neotectonic plate signatures abstract it is the contention of the present author that surface joints are signatures of the plate tectonic stress field according to the writer s view joints are shear features caused by plate tectonic stresses with the maximum compression axis lying in the smaller quadrant formed by the regional sets these contentions are substantiated by new joint measurements geotectonic lines in europe are reflected in the joint orientations and the subduction direction in the philippines is indicated by them other instances of joints being plate tectonic signatures which have been published previously are referred to

compaction control of topography and fault network structure along strike slip faults in sedimentary basins strike slip faults commonly display structurally complex areas of positive or negative topography understanding the development of such areas has important implications for earthquake studies and hydrocarbon exploration previous workers identified the key factors controlling the occurrence of both topographic modes and the related structural styles kinematic and stress boundary conditions are of first order relevance surface mass transport and material properties affect fault network structure experiments demonstrate that dilatancy can generate positive topography even under simple shear boundary conditions here we use physical models with sand to show that the degree of compaction of the deformed rocks alone can determine the type of topography and related surface fault network structure in simple shear settings in our experiments volume changes of 5 are sufficient to generate localized uplift or subsidence we discuss scalability of model volume changes and fault network structure and show that our model fault zones satisfy geometrical similarity with natural flower structures our results imply that compaction may be an important factor in the development of topography and fault network structure along strike slip faults in sedimentary basins

transform margin of the northern levant eastern mediterranean from formation to reactivation 1 the levant continental margin eastern mediterranean is usually defined as a passive margin that developed between the late paleozoic early mid mesozoic previous studies suggest that the margin is composed of two segments with different structural characteristics the southern segment south of the carmel structure was formed by rifting whereas the origin of the northern segment is not known the present study focuses on the northern segment which is a key for understanding the tectonic history of the eastern mediterranean investigation is carried out offshore on two scales 1 deep crustal observations analysis of seismic refraction and magnetic data and their comparison with other continental margins worldwide and 2 shallow crustal scale observations of recent tectonic deformations based on multichannel and single channel seismic reflection profiles integration of the deep and shallow observations with reevaluation of geological data onland show strong structural resemblance between the northern levant segment and other transform margins a modified scenario is suggested for the formation and development of the levant basin and its margins combining all previous studies into one simple picture where a signature of older structures on more recent features is evident located in the midst of the progressive afro eurasian collision the northern levant presents a unique lifecycle for transform margins worldwide from formation to reactivation

segmentation of the levant continental margin eastern mediterranean 1 the levant continental margin is divided into two major segments by the carmel structure which extends from the dead sea fault into the eastern mediterranean new seismic reflection data over the unexplored northern segment are used for completing the structural framework of the levant area together with existing data south of it inclusive depth structural maps of the area were produced for the base pliocene and base messinian evaporites previous studies indicate that differences between the two segments are well expressed in the deep crustal structure the present study which focuses mainly on the shallow section shows that these differences are maintained throughout the accumulation of young sedimentary units and even in the bathymetry this preservation of segmentation both in the shallow and in the deep structure insinuates that the two segments were formed through different continental breakup processes which continue to dictate the style of sediment accumulation

the nature of small to medium earthquakes along the eastern mediterranean passive continental margins and their possible relationships to landslides and submarine salt tectonic related shallow faults

tectonic isolation of the levant basin offshore galilee lebanon effects of the dead sea fault plate boundary on the levant continental margin eastern mediterranean abstract the continental margin of the central levant offshore northern israel and southern lebanon is characterized by a sharp continental oceanic crustal transition exhibited on the bathymetry as a steep continental slope at the base of the slope a narrow zone of faulting deforms the upper messinian recent sedimentary sequence further into the basin no major deformations are observed however onland a restraining bend along the dead sea fault plate boundary results in the formation of the lebanon and anti lebanon mountain ranges which exhibit a large positive isostatic anomaly not compensated at depth all these geologic features follow a nne ssw trend a dense network of multi channel and single channel seismic profiles covering 5000 km of ship track offshore northern israel and southern lebanon was analyzed for the purpose of characterizing the continental margin additional seismic surveys covering the area between the levant margin and the cyprean arc were examined data were then incorporated with magnetic gravity and earthquake measurements to reveal the deep crustal structure of the area and integrated with bathymetry data to describe the behavior of the young sedimentary basin fill results indicate that the levant basin offshore northern israel and southern lebanon up to beirut is more or less unaffected by the intense tectonic deformation occurring onland the transition between the deformed area onland and the undeformed levant basin occurs along the base of the continental slope along the base the upper messinian recent sedimentary sequence is cut by two sets of faults shallow growth faults resulting from salt tectonics and high angle faults marking the surface expression of a deeper crustal discontinuity the marine extension of the carmel fault zone the central levant continental margin is being reactivated by transpressional faulting of the marine continuation of the carmel fault at the base of the continental slope this fault system coincides with the sharp continental oceanic crustal transition and acts as an isolator between the levant basin and its land counterpart to the north this feature may initiate the formation of a new triple junction with the latakia ridge part of the eastern cyprean arc and the east anatolian fault

initiation of gravitational collapse of an evaporite basin margin the messinian saline giant levant basin eastern mediterranean regional 2d and 3d seismic data from the levant basin reveal the updip extensional component of thin skinned gravity tectonics on this continental margin because of its youth 5 7 ma the earliest stages of deformation of this salt basin are preserved without the severe structural overprinting common on more mature giant salt tectonic systems extension detaches onto and within messinian evaporites up to 1800 m thick by structural restoration we reconstruct the tectonic evolution of the messinian evaporites using paleobathymetric constraints from wells and seismic profiles this analysis suggests that the mediterranean drawdown during the messinian salinity crisis was 800 m the 10 to 15 km wide extensional domain tracks the landward pinch out of the mobile messinian evaporites against an older late miocene scarp diachronous extension began in the center of the margin in the mid pliocene then spread northward in the late pliocene then finally southward in the early pleistocene extension continues today on many of the most landward faults extensional strain varies greatly along strike from 1 km to as much as 12 15 km comparing observations with four end member conceptual models we infer that both extension and seaward salt flow thinned the evaporite margin and its overburden both processes were triggered by a combination of uplift of the continental shoulder of the dead sea rift and subsidence in the mediterranean basin at least three factors controlled variations in extension 1 degree of tilting of the salt wedge related to the interplay of coastal uplift and basin subsidence 2 presence of pre messinian canyons overlain by landward salients of salt and 3 variations in evaporite facies and the proportion of siliciclastic admixture

magnetic anomalies over the central levant continental margin abstract the magnetic field over the central levant continental margin off northern israel and southern lebanon and the adjacent levant basin has two distinct trends mount carmel and its offshore continuation carmel nose which are the surface expression of a large subbottom structure that extends from the land area across the continental shelf to the continental slope form a dividing zone between the two magnetic trends south of the carmel structure the magnetic field trends east west while north of the carmel structure it trends northeast and north northeast several pronounced magnetic anomalies exist mainly north of the carmel structure the majority of which trend north northeast and northeast parallel and sub parallel to the trend of the magnetic field in this area some also trend northwest perpendicular to the trend of the magnetic field in several cases the magnetic anomalies indicate large lithological elements which continue from land to sea gravity and seismic refraction data show that the two magnetic domains north and south of the carmel structure are associated with areas of different crustal structure south of the carmel structure the continetal oceanic crustal transition zone is located beyond the continental margin at the base of the continental slope while north of the carmel structure it is located under the continental shelf near the shore on land there are also differences in the structure of the crust north and south of the carmel structure the crust being much thinner north of the structure than south of it we suggest that some of the large magnetic anomalies off the central levant were formed during the rifting phase of the eastern mediterranean

tectonic evolution of the eastern mediterranean basin and its significance for hydrocarbon prospectivity in the ultradeepwater of the nile delta the northeast mediterranean deepwater area 41 500 km2 was awarded to shell egypt in july 1998 operations started on 1 february 1999 to acquire a 7000 km 2 d 6 km cable 8 s 120 fold seismic survey key pre 1999 data included a 1500 km 2 d seismic 1973 vintage in december 1999 exxon exploration and production egypt acquired a 25 interest in the concession

paleostress analyses in nw syria constraints on the cenozoic evolution of the northwestern margin of the arabian plate abstract fault analysis between the dead sea transform and the euphrates region in northern syria shows two main directions of compression connected to the recent evolution of the northwestern wedge of the arabian plate e w open folds due to n s compression gently deform the cretaceous to tortonian successions of the aleppo plateau and the eastern termination of the palmyrides west of the euphrates conjugate sets of strike slip and normal faults pre as well as post dating folding occur in the plateau and are still consistent with the same stress field n s normal faults cross recent deposits and control quaternary volcanoes along the euphrates suggesting the persistence of this stress regime a nw se compression related to the syrian segment of the dead sea transform dst was detected in the western part of the study area the activation of large n s left lateral strike slip and wnw ese right lateral faults follows in time the growth of in line folds and thrusts permutation of the 1 and 2 stress axes is related to activation of nw se normal faults which generally accompany strike slip faults and post date e w folds within the plateau recent e w extension in the euphrates region is consistent with a horizontal n s maximum direction of compression and seems to be partially coeval with the stress regime induced by the dst this stress pattern can be explained by the superposition of the northward push of the arabian plate to the n s left lateral shearing along the dst

seismic activity along fault branches of the dead sea jordan transform system the carmel tirtza fault system abstract about 550 earthquakes 1 0 m l 5 3 along the carmel tirtza fault a branching fault of the jordandashdead sea transform system recorded by the israel seismograph network isn between 1984 and 1994 were analyzed the seismicity pattern reveals significant activity often confined to known surface traces of active faults or within local grabens earthquake clusters are also observed the seismicity pattern within the mediterranean seems more diffuse possibly due to observational inaccuracies and insufficient knowledge of how the carmel tirtza fault system extends towards the northwest the seismicity along the carmel tirtza fault system since the beginning of this century is characterized by a b value of about 0 9 for 15 events with 3 1 m l 5 3 we found seismic moment estimates m 0 of 0 7 10 14 m 0 10 17 nm and brune stress drop estimates between 0 9 and 16 4 mpa these characteristics are comparable to those for events occurring on the main dead sea jordan transform fault ten individual earthquake focal mechanisms and three joint focal mechanisms for earthquake clusters have been obtained towards the northeastern part of the carmel tirtza fault system a left lateral motion seems to dominate while the seismicity pattern and the focal mechanism solutions near the branching of the carmel tirtza fault and the dead sea jordan rift suggest the present day existence of a complicated tectonic regime stress inversion assuming one stress tensor for the whole region indicates nne ssw extension and wnw ese compression

some outstanding issues in the geology of lebanon and their importance in the tectonic evolution of the levantine region abstract the concept of pervasive and disruptive late neogene quaternary strike slip tectonics in lebanon has made establishing a satisfactory pre neogene palaeogeographic and palaeotectonic history for the area difficult research has allowed clarification of three fundamental issues that permit the setting of lebanon against its adjacent regions to be more firmly assigned the first issue is the identification of the significance of the 100 km long nne ssw trending monocline of the western lebanon flexure this feature is interpreted as a modified and rejuvenated early mesozoic hinge line that is presumed to be the northern continuation of the carmel sinai hinge line to the south the second issue is the correlation of the mount lebanon bekaa and anti lebanon complex with the adjacent intracontinental palmyride fold belt of syria through recognition in each of common divisions in structural style between a higher northern zone dominated by broadly spaced box folds and a lower southern zone with more numerous closely spaced and more internally complex folds the third issue involves the identification of major two stage late cretaceous to palaeogene syrian arc tectonism within lebanon resolution of these issues suggests a tectonic model for the region whereby the levantine region formed in two main phases the first of these was the multiphase late palaeozoic early mesozoic rifting of the area which imposed a fundamental extensional fabric over much of the region the second tectonic phase was the subsequent inversion of these extensional structures in the two stage syrian arc deformation of senonian and late palaeogene age which gave rise to the main lebanon structures it is this syrian arc tectonism rather than the late cenozoic strike slip that was probably the main structuring agent which affected the lebanon area the transpression from the braided dead sea fault motion although locally complex is an essentially neotectonic overprint on an already existing fabric offset of syrian arc structures in lebanon suggests that the total sinistral motion of the yammouneh fault segment of the dead sea fault is around 47 km

late tertiary seismic facies and structures of the levant passive margin off central israel eastern mediterranean abstract the late tertiary seismic facies and structures of the levant passive margin off central israel in the eastern mediterranean sea were studied by the interpretation of more than 3000 km of seismic reflection profiles most of them previously unpublished single channel profiles the neogene growth and evolution of this margin was influenced by the interaction of three main processes 1 the outbuilding and loading of the margin by the nile sediments since the pliocene 2 uplift and tectonic subsidence related to the tectonic activity along the dead sea transform and 3 the effect of the above processes on the thick messinian evaporites which caused many salt tectonic features including flowage piercement diapirs slumps and en echelon listric normal faults in the supra salt sediments we suggest that the study area may be divided into two segments north and south of caesarea these segments vary in their depositional environment the amount of sediment supply and load salt related features and tectonic activity we propose that the northern segment is affected by low sediment supply and by the continued uplift of the carmel structure and that this segment may even be a part of this structure the southern segment has been affected by the deposition and loading in the nile derived sediments since the pliocene three main depositional sequences were observed in the southern segment 1 sequence i early pliocene onlaps the top of the messinian evaporites representing a rise of sea level and renewed subsidence 2 sequence ii early pleistocene is lens shaped thinning to the north west and east and was derived during a relatively short time interval from the pre nile and 3 sequence iii since the pleistocene represents a major episode of continental shelf construction

seismic anisotropy above and below the subducting nazca lithosphere in southern south america 1 the goal of this study is to better constrain anisotropy and mantle flow above and below the nazca slab from 28 s to 42 s through modeling of shear wave splitting in local s sks and skks sk k s phases comparisons of local s splitting times and path lengths in the slab mantle wedge and upper plate indicate that splitting times for arc and back arc stations are consistent with anisotropy in the mantle wedge but long slab paths to fore arc stations imply that slab anisotropy is also significant sk k s shear wave splitting observations and models for sub slab anisotropy show that significant anisotropy is present below the slab and that the orientation of sub slab anisotropy sometimes differs from anisotropy above the slab anisotropy both above the slab and below the slab in the south american subduction zone is consistent with mantle flow that is driven by a combination of entrainment with downgoing slab motion and flow complexity related to variations in slab shape and slab rollback

what triggered the early to mid pleistocene tectonic transition across the entire eastern mediterranean abstract subduction plays a fundamental role in plate tectonics and when interrupted it may trigger a series of geodynamic and sedimentary responses synchronous structural modifications recorded across the entire eastern mediterranean region are dated to a relatively short period early to mid pleistocene these deformations are documented within plates e g arabian sinai and african plates along plate boundaries e g dead sea and north anatolian faults and cyprus arc and in the mediterranean basin during the same period the northward subduction of the sinai plate was interrupted when the eratosthenes seamount cyprus arc collision initiated subduction collision processes of the eastern mediterranean serve as a unique modern analogue for similar settings worldwide understanding their association with accompanying neo tectonic processes is therefore predominantly important by fostering a detailed and comprehensive approach this research provides a coherent tectonic picture for the eastern mediterranean early to mid pleistocene tectonic transition in order to explore its triggering mechanisms since the neogene convergence across the eastern mediterranean was accompanied by eurasian indentation by arabia northward motion westwards anatolia escape and southwards aegean propagation this semi counterclockwise plate motion was temporarily interrupted by the incipient seamount arc collision which is suggested here as a trigger of the early to mid pleistocene tectonic transition

mechanical aspects of pull apart basins and push up swells with applications to the dead sea transform abstract pull apart basins and push up swells are common features at steps along strike slip faults the structure of these features is examined here for two types of rheology perfect brittle and perfect ductile the stress fields derived for the step area predict that fault patterns mode of deformation and vertical displacement are different for the two rheologies these predictions are illustrated for basins and swells developed in laboratory experiments with modelling materials the structure of basins and swells along the dead sea transform is discussed here the pull apart basins display an intensively faulted southern end and a gently dipping flexure at the northern end a consistent dissimilarity appears between the structures of the eastern and western boundary faults of the basins according to the present interpretation these dissimilarities reflect a relatively ductile crust in arabia and a relatively brittle crust in sinai israel

structure and tectonics of the eastern cyprean arc abstract the geometry and nature of the eastern segment of the cyprean arc are little understood several hypotheses have been put forward to explain the tectonic situation there recent marine geophysical data for this region mapped several deep and shallow structural elements the most prominent element is a ridge the latakia ridge which extends from the syrian coast near latakia south westward to meet with an east west trending bathymetric escarpment east of the hecateus ridge the new seismic profiles suggest that these two elements mark the present plate boundary along the eastern cyprean arc the latakia ridge is a young and still active feature it was formed by southward migration of the plate boundary the ridge probably originated as a large thrust sheet which later when the convergence direction was changed became a zone of wrench faulting the ridge is still forming today and serves as a dam to the sediments north of it the wrench faulting activity is more pronounced in the eastern segment of the ridge

crustal structure of the levant basin eastern mediterranean abstract a seismic refraction wide angle reflection experiment was undertaken in the levant basin eastern mediterranean two roughly east west profiles extend from the continental shelf of israel toward the levant basin the northern profile crosses the eratosthenes seamount and the southern profile crosses several distinct magnetic anomalies the marine operation used 16 ocean bottom seismometers deployed along the profiles with an air gun array and explosive charges as energy sources the results of this study strongly suggest the existence of oceanic crust under portions of the levant basin and continental crust under the eratosthenes seamount the seismic refraction data also indicate a large sedimentary sequence 10 14 km thick in the levant basin and below the levant continental margin assuming the crust is of cretaceous age this gives a fairly high sedimentation rate the sequence can be divided into several units a prominent unit is the 4 2 km s layer which is probably composed of the messinian evaporites overlying the evaporitic layer are layers composed of plio pleistocene sediments whose velocity is 2 0 km s the refraction profiles and gravity and magnetic models indicate that a transition from a two layer continental to a single layer oceanic crust takes place along the levant margin the transition in the structure along the southern profile is located beyond the continental margin and it is quite gradual the northern profile north of the carmel structure presents a different structure the continental crust is much thinner there and the transition in the crustal structure is more rapid the crustal thinning begins under western galilee and terminates at the continental slope the results of the present study indicate that the levant basin is composed of distinct crustal units and that the levant continental margin is divided into at least two provinces of different crustal structure

large scale submarine rotational slumps and growth faults in the eastern mediterranean submarine slumps with areas of 1000 km2 and more disturb the continental margin of israel and nearby areas in them the plio quaternary silty clayey sediments up to 1 5 2 km thick are broken by shore parallel growth faults into 5 10 blocks which are generally rotated and tilted landward the faults flatten downward and become rooted in ridges formed by deformation of the underlying mobile messinian evaporite bearing series deformation is thin skinned and does not visibly extend to deeper levels slumping occurred only where a sufficiently thick overburden accumulated over a sufficiently well developed mobile substrate then gravitational instability developed and led to basinward sliding of the continental margin sediments over the messinian series which acted as a lubricant and a level of decollement the mobility of this series is probably caused by overpressured shale beds that are confined between the impervious evaporites this mechanism explains all the features of the slumps hitherto faults directly related to the slumps of the eastern mediterranean were not identified but since the region is tectonically active it is not possible to exclude the possibility that basinward sliding was triggered either by motion of minor underlying faults or by seismic shaking however it seems that even if this were the case slumping could be triggered only because the continental margin was anyhow gravitationally unstable or close to such a state therefore the gravitational instability was the main factor that controlled the deformation of the pliocene quaternary sediments the slumps of the eastern mediterranean resemble large scale slumps that are known from other passive continental margins in the world

plate convergence in the cyprean arc abstract the cyprean arc is a part of the plate boundary between afro arabia and eurasia in the eastern mediterranean a re examination of the geophysical properties of the cyprean arc together with an analysis of multichannel seismic reflection profiles now available in the cyprean arc area provides a clearer view of the tectonic setting and processes in this region seismic activity and a gravity anomaly indicate that a northward subduction of oceanic material related to the african plate beneath the turkish plate is the mode of convergence along the western segment of the cyprean arc subduction is interrupted due to the collision of the eratosthenes seamount at the central segment of the cyprean arc which forms a zone of intense deformation the zone of deformation spreads away and disappears in the eastern segment of the cyprean arc no signs for deformation have been found in this portion either in the multichannel seismic reflection profiles in the seismicity or in the bathymetry the change in the mode of convergence and in the type of deformation along the cyprean arc is induced by crustal differences in the underthrusting plate interruption of subduction activity in one segment of the arc also affects the geometry of nearby segments and the processes over there

crustal and upper mantle structure across the dead sea rift and israel from teleseismic p wave tomography and gravity data abstract new findings of the structure of the crust and the upper mantle across the dead sea rift and israel were obtained by applying p and pkp wave relative travel time residuals inversion of 612 teleseisms recorded by the seismic networks in israel and jordan independently of the relative teleseismic travel time residuals the bouguer gravity anomalies were used as an additional aid to examine the structure of the crust and upper mantle an examination of the teleseismic travel time residuals in israel suggests the existence of two prominent provinces of distinct crustal structure the northward increase of the teleseismic travel time residuals is in good agreement with a gradual thickening of the sedimentary sequence and a simultaneous thinning of the crust examination of the inverted velocity anomalies indicates that the upper and lower crusts are sub divided into a number of structures we identify several velocity anomalies that are associated with prominent geological structures the southern dead sea basin is characterized with the largest decrease of velocity in both upper and lower crustal layers due to the infilling of light material relative to the surrounding material the velocity anomaly in the carmel structure is probably associated with variations in the upper part of the upper mantle examination of a cross section that traverses the dead sea transform supports the existence of lighter mass density material on the eastern side relative to that on the western side

inland jump of the arabian northwest plate boundary from the levant continental margin to the dead sea transform 1 while the breakup of arabia and africa began in the early oligocene the northwestern boundary of the arabian plate along the dead sea transform dst formed 10 15 myr later early middle miocene during the early stage of breakup the red sea rift continued propagating northwestward forming the suez rift the present 45 northward twist of the plate boundary from the red sea toward the gulf of eilat aqaba still did not exist what happened at the northern tip of the suez rift at that time how was strain distributed to its surroundings and where did the plate boundary continue from there here we describe an abandoned segment of the arabian northwestern plate boundary that extended from the northern tip of the suez rift northeastward along the levant margin seismic data collected offshore israel support a subsurface deep rooted fault zone running along the base of the continental slope these faults indicate oligocene transpressional lateral shearing we propose that during the early stage of continental breakup a left lateral strike slip motion of 10 km took place along this embryonic plate boundary such deep rooted tectonism implies that unlike the passive situation of the israel sinai continental margin witnessed presently and before the oligocene during the early stage of the africa arabia breakup this part of the continental margin was reactivated we further suggest that the inland jump of the plate boundary toward the dst was not immediate and that during the transitional period the israel sinai triangular block was an independent subplate with deformation all around it

levant jet system effect of post lgm seafloor currents on nile sediment transport in the eastern mediterranean abstract sedimentary development of a continental margin is directly related to seafloor current dynamics yet the linkage between the processes remains vague due to the different time scales they represent to narrow this gap we focus on the thoroughly studied distribution system of nile derived sediments across the levant continental margin eastern mediterranean these sediments dominate the late quaternary stratigraphy of the entire margin their mobilization has been explained exclusively by longshore transport while oceanographic evidence from the basin and margin are not incorporated in the known mechanism new data indicates that longshore mechanism is part of a much larger system based on integrated interpretation of multibeam bathymetry high resolution single channel seismic reflection and oceanographic temperature salinity and chlorophyll data we suggest a jet current system mobilizes the levant surface water lsw levant intermediate water liw and atlantic water aw northwards along the margin between 0 and 400 m water depths on the seafloor contourite currents form elongated along strike morphologies below 400 m along dip gravity flows dominate sediment transport to down the slope below the eastern mediterranean deep water emdw initiation of this mechanism during the pleistocene holocene transition and not at the end of the last glacial maximum lgm indicates a gradual recovery of the thermo haline circulation current intensification in the early holocene may have also increased water stratification this comprehensive mechanism explains sediment transport along the entire depth range of the continental margin while integrating seafloor currents morphology as well as their relation to sea level rise and stratigraphy of water masses in the levant basin since the lgm given the consistency of seafloor currents throughout the holocene we propose to address them as the levant jet system

aeolian beach ridges and their significance for climate and sea level concept and insight from the levant coast east mediterranean abstract relict beach ridges of aeolian origin and associated soils are often used for inferring relative sea level and climate with contrasting results most studies link the aeolian coastal deposits to regressive phases some to high sea level stands and a few to intermediate relative sea level positions we interpret the apparent contradictions as indicating the lack of an over arching concept and the inconsistent usage of sea level related terms in this paper we present an integrated morpho sedimentological concept for a microtidal mid latitudinal coast and review existing data from the levant east mediterranean coast to evaluate the concept and to eliminate nomenclatural confusion a coastal depositional environment in a semi arid environment consists of shallow marine aeolian and alluvial facies which together form an aeolian beach ridge complex as a package of strata which respond simultaneously to sea level change a transgressive complex forms through reworking or overstepping of the coastal foredune and a regressive complex forms by downstepping under transgression the aeolian beach ridge represents the highstand deposit and its adjacent shallow marine sediment is the transgressive deposit under regression the complex represents the falling stage and the associated downdip surface marks the lowstand on the levant coast we find chronologically well constrained offlapping aeolian beach ridges as parts of six downstepping beach ridge complexes formed between 200 ka and 10 ka the complexes represent the falling stage systems tract fsst of a short lived 5th order depositional sequence when the shoreline shifted from a position close to the modern coastline to the shelf or below the shelf edge three of these fssts and their up dip and down dip super bounding surface together form the 4th order 100 ka sequence of the last interglacial glacial cycle the absence of transgressive highstand and lowstand systems tract is explained by the poor preservation potential due to the small sediment budget of the complex the falling stage complex has a high preservation potential because sediment source area increases while the sand drift potential remains above the local threshold on the levant coast sand delivery to the backshore continued during relative sea level falls for distances of up to 10 km between dune and coastline which is unprecedented in most modern analogues the significance of the dune soil succession for climate is limited because the dunes are governed by relative sea level change the vegetation response to changes in precipitation is non linear and the dune dynamics are characterised by low resilience and hysteresis

the crust and uppermost mantle structure of southern peru from ambient noise and earthquake surface wave analysis abstract southern peru is located in the northern central andes which is the highest plateau along an active subduction zone in this region the nazca slab changes from normal to flat subduction with the associated holocene volcanism ceasing above the flat subduction regime we use 6 s to 67 s period surface wave signals from ambient noise cross correlations and earthquake data to image the shear wave velocity v s v structure to a depth of 140 km a mid crust low velocity zone is revealed and is interpreted as partially molten rocks that are part of the andean low velocity zone it is oblique to the present trench and possibly indicates the location of the volcanic arcs formed during the steepening of the oligocene flat slab beneath the altiplano plateau the recently subducted slab beneath the forearc shows a decrease in velocity from the normal to flat subduction regime that might be related to hydration during the formation of the nazca ridge which in turn may contribute to the buoyancy of the flat slab the mantle above the flat slab has a comparatively high velocity which indicates the lack of melting and thus explains the cessation of the volcanism above a velocity contrast from crust to uppermost mantle is imaged across the cusco vilcanota fault system and is interpreted as the boundary between two lithospheric blocks

structures and kinematics in the northeastern mediterranean a study of an irregular plate boundary abstract extensional structures are prominent in the northeastern mediterranean a unique sector of the africa eurasia plate convergence zone to explain this paradoxical situation we analyse here the young tectonics of this region by examining its structural elements and plate kinematics offshore multichannel seismic reflection profiles and onland geology show that the stuctural settings are different on the two sides of the northeastern mediterranean triple junction afr arb ana on the east stuctures controlled by strike slip and by compression coexist whereas on the west compression is not very conspicuous here deep basins separated by a partly submerged ridge are prominent we interpret the ridge which comprises the kyrenia misis andirin unit at its core as a large flower structure which extends from southeastern turkey to cyprus the adana cilicia and the iskenderun latakia mesaoria basins on its flanks are interpreted as due to extension this interpretation agrees with the relative motions between the africa arabia eurasia and anatolia plates in this region analysis of the local plate kinematics reveals that strike slip predominates along the southern boundary of the anatolia plate in this region as a result of anatolia s westward escape east of the triple junction this motion is associated with comparable shortening transverse to the plate boundary whereas west of the triple junction the motion transverse to the plate boundary varies between slight compression to extension depending mainly on the local strike of the plate boundaries these variations calculated from regional data correlate well with the observed structural changes along the northeastern mediterranean sector of the plate convergence zone the structural kinematic analysis explains both the lateral changes in the deformation style and the existence of local extension in the northeastern mediterranean

age and structure of the levant basin eastern mediterranean abstract large parts of the mediterranean were formed during the mesotethys ocean opening and subsequently became land locked in the midst of the africa eurasia plate convergence since the neogene this convergence has concealed key sections of the original basins previous studies widely agree that the easternmost part of the mediterranean the levant basin opened during the permian to early jurassic pj and accordingly explain the architecture of the basin and its margins however since the pj model was suggested in the late 1990 s a flood of new evidence has arrived since the hydrocarbon exploration some of which do not fit in with the pj model and some remain unexplained the current research re examines the old and new evidence from the levant basin its margins the surrounding landmass the adjacent eratosthenes seamount and the eastern part of the herodotus basin the integration of geological and geophysical data suggests that the levant basin formed 100 myr later than previously thought i e during the cretaceous its opening was triggered by the levant nubia mantle plume that induced a sequence of wide spread ocean island basalt volcanism the resulting crustal updoming and stretching led to the breakup of the levant landmass since 141 ma and drifting of the eratosthenes seamount since 125 ma back arc extension shaped the levant basin as a hybrid crust comprising continental slivers intervened by oceanic patches the basin opened during the long normal cretaceous polarity chrons between 122 and 84 ma and therefore it does not show any magnetic lineation the opening of the levant basin occurred while the herodotus basin floor subducted eastward under the eratosthenes seamount the subduction hinge did a roll back and facilitated the seamount drifting the seamount absorbed intensive volcanism while chasing the subduction roll back and sliding between two subduction transform edge propagator step faults that bounded the stretching levant back arc basin the turonian maastrichtian compression stress regime or inversion halted the extension of the levant basin stagnated its hybrid fabric and prevented the development of a spreading center the evolutionary scenario suggested here is a game changer for future exploration in the levant and may serve as a global analog for the formation of marginal seas

crustal configuration in the northern levant basin based on seismic interpretation and numerical modeling abstract the interpretation of five 2d pstm seismic reflection sections 14 s twt covering the northern levant basin revealed a total of 10 horizons among which one is interpreted as an interface that may represent the moho the interpretation of seismic packages and their bounding surfaces as well as the seismic facies analysis were constrained by published 2d seismic interpretations of the northern lebanese offshore a total of nine seismic packages are identified in the basin with ages varying from the mid jurassic to the quaternary the filling of the basin is made up of thick cenozoic and mesozoic strata deposited above rifted triassic early jurassic interval the sediments are deposited in deep water mixed settings resulting from high stand systems various types of carbonate platforms and low stand systems siliciclastic and carbonate deep water turbidite complexes carbonate and siliciclastic systems are sealed by 1 1 5 km of evaporites and underlie plio quaternary hemipelagic and pelagic sediments intercalated by turbiditic sheets the time horizons were converted into depth using two methods the first one is based on stacking velocities and the second one on velocities resulting from refraction data 2d crustal modeling was achieved by integrating free air gravity anomaly geoid heights and topography data on the five interpreted pstm seismic lines the models representing five sections across the northern levant basin show a progressively attenuated crystalline crust in an ew direction away from the basin s eastern margin the crystalline crust is best interpreted as a strongly thinned continental crust under the levant basin represented by two distinct components an upper and a lower continental crust the moho appears to be situated between 20 and 23 km in the central and southern lebanese offshore estimated surface heatflow in the basin is around 40 mw m2 which is lower than reported values for the onshore and the margin these differences in heatflow values between the offshore the margin and the onshore have an important impact on hydrocarbon maturation and assessment of potential petroleum systems

filling up the shelf a sedimentary response to the last post glacial sea rise abstract following the last glacial maximum lgm lowstand global sea level rose by 120 m flooding previously exposed continental shelves worldwide with water and sediments in these drowned environments sediment accumulation patterns are dictated by a superposition of vertical tectonic motion sea level change and sediment supply rates which are hard to distinguish from one another this study focuses on a unique region where the first two components are known and well constrained the terminal part of the nile littoral cell along the eastern mediterranean continental margin data analysis is based on detailed interpretation of four newly obtained high resolution seismic reflection surveys integrated with two industrial seismic surveys the age of sedimentary sequences is constrained by correlation with drillholes while accumulation patterns strongly correlate with the local model based sea level curve our sub meter resolution seismic stratigraphy reveals post lgm shoreline migration and suggests a seismic based sea level curve since data presented here provide the first direct insight into the sedimentary accumulation pattern they are used to calibrate the modeled curve this simple yet innovative approach stresses the importance of high resolution seismic reflection data to sea level research worldwide while serving as a reference for the entire mediterranean sea

a braided strike slip model for the northern continuation of the dead sea fault and its implications for levantine tectonics abstract the assumption that the 100 110 km sinistral displacement on the dead sea fault is transmitted northwards along a single structure the yammouneh fault which runs ne sw across lebanon is here reviewed a number of valid objections to this concept exist a more attractive model supported by the limited data available from the area is that the motion is transmitted along a number of faults on this basis the temporary rightward flexure of the levant fracture through lebanon has given rise to a braided strike slip fault complex the yammouneh serrhaya fault system this model overcomes the objections against the older concept and allows the explanation of the mt lebanon bekaa valley anti lebanon complex in terms of transpressive and transtensive blocks a tentative outline of the cenozoic structural evolution of the area in terms of two or more phases of motion along the levant fracture is presented

faulting processes along the northern dead sea transform and the levant margin the northern dead sea transform is markedly different from the southern segments of the transform the strike of the transform changes in this area that forms a restraining bend and the displacement on it is much less than that on the southern and central dead sea transform the structure and evolution of the northern dead sea transform was simulated using a rheological model of a visco elastic material that takes into consideration the crustal structure variations in this area and the proximity to the collisional belts along the cyprean arc and the taurus mountains the simulation can explain the formation of the restraining bend known in this area as the yammuneh fault and the faulting along the northern levant continental margin providing that a simultaneous propagation of the dead sea transform from the north and south took place this suggests that restraining bends in general which are common features along continental transform faults are formed when two segments of a transform propagate toward each other

subduction collision and initiation of hominin dispersal subduction is the main driving force of plate tectonics controlling the physiography of the earth the northward subduction of the sinai plate was interrupted during the early pleistocene when the eratosthenes seamount began to collide with the cyprian arc a series of synchronous structural deformations was triggered across the entire eastern mediterranean and local topography was drastically accentuation along the levantine corridor one of the main pathways of hominin dispersal out of africa however the choice of this preferred pathway and timing of dispersal has not been resolved though causes for dispersal out of africa are in debate we show that the transition from subduction to collision in the eastern mediterranean set the route

melt instabilities in an intraplate lithosphere and implications for volcanism in the harrat ash shaam volcanic field nw arabia we investigate melt generation in a slowly extending lithosphere with the aim of understanding the spatial and temporal relationships between magmatism and preexisting rift systems we present numerical models that consider feedback between melt generation and lithospheric deformation and we incorporate three different damage mechanisms brittle damage creep damage and melt damage melt conditions are calculated with a helmholtz free energy minimization method and the energy equation is solved self consistently for latent heat and shear heating effects using a case of a slowly extending 1 1 5mm yr continental lithosphere with a relatively low surface heat flow similar to 50mw m 2 we show that melt rich shear bands are nucleated at the bottom of the lithosphere as a result of shear heating and damage mechanisms upon further deformation melt zones intersect creep damage zones thus forming channels that may be used for the melt to migrate upward if a preexisting structure resides only in the brittle crust it does not control the path of melt migration to the surface and melt filled channels propagate from the bottom upwards independently of upper crustal structures in contrast a preexisting weak structure that reaches a critical depth of 20km allows fast similar to 2ma propagation of melt filled channels that link melt damage from the bottom of the lithosphere to near surface structures our model results may explain the short time scale volume and magma extraction from the asthenosphere through a low surface heat flow lithosphere such as observed for example in the harrat ash shaam volcanic field northwestern arabia which developed in the arabian plate and is spatially linked to the azraq sirhan graben

a mid pleistocene deformation transition in the hula basin northern israel implications for the tectonic evolution of the dead sea fault the dead sea fault dsf plate boundary has accommodated relative sinistral motion between the sinai and arabian plates since the neogene geologically based models point to a long term 5 0 ma n trending relative motion roughly parallel to the central sector of the dsf gps based calculations of present day relative motion between the sinai and arabian plates indicate a northward increasing convergent component across the dsf suggesting a kinematic change over the plio pleistocene period we study the evolving deformation of the hula rhomb shaped graben situated along the central sector of the dsf in order to examine the possible kinematic change the hula graben is widely accepted as a pull apart basin part of a series of basins extending southward we use a 3 d approach combining mapped surface structures with subsurface seismic reflection profiles 173 km and borehole data 38 boreholes gathered here into a single geographic information systems database results indicate that during the mid pleistocene a major tectonic transition modified the structure of the basin fill a subvertical nnw trending left lateral throughgoing strike slip fault developed diagonally across the basin consequently the basin entered a new geodynamic phase where subsidence was controlled by both the basin bordering faults and the diagonal fault while the vertical displacement across the transverse faults is minor synchronous structural changes recorded in additional localities along the dsf attests to a mid pleistocene 1 ma regional tectonic transition that was associated with a northward increasing convergent component across the central and northern sectors of the dsf

constraints on the post 25 ka slip rate of the yammouneh fault lebanon using in situ cosmogenic 36cl dating of offset limestone clast fans the most active seismogenic structure along the eastern shore of the mediterranean is the n s trending left lateral levant fault system lfs the plate boundary between arabia and africa in lebanon it forms a 160 km long restraining bend responsible for the uplift of mount lebanon the resulting transpression is partitioned between the offshore tripoli roum thrust and the yammouneh strike slip fault there are few quantitative constraints on the quaternary slip rate along the lfs here we present a direct estimate of the 25 ka mean slip rate on the yammouneh fault mapped offsets of alluvial fans at two sites 50 km apart on the eastern flank of mount lebanon range between 24 2 and 80 8 m about 30 limestone cobbles sampled on these fans yield in situ cosmogenic 36cl exposure ages mostly between 6 and 27 ka a statistical assessment of offsets versus ages provides bounds on the late pleistocene holocene slip rate on the fault 3 8 6 4 mm yr these results are consistent with long term geological inferences confirming that the yammouneh fault is the main strike slip branch of the lfs in lebanon they illustrate both the potential and the difficulties of using in situ cosmogenic 36cl dating of limestone clast fan deposits for deciphering tectonic and geomorphic processes in the mediterranean

the deep structure of the carmel fault zone northern israel from gravity field analysis the carmel yizre el jordan fault system is a major structural feature in the geology of israel there is a great difference in topographical features structural style seismic activity crustal structure and other geological characteristics to the north and south of this fault system we examine the gravity field of the region around the fault system by combining the techniques of upward continuation and horizontal gradient analysis the results suggest the existence of a system of deep seated n s trending faults that are probably related to the continental breakup of the region in the triassic jurassic the present complex deformation of the area is the result of interaction between the older faults system and the younger stresses resulting from the formation of the dead sea rift

displaced terranes and crustal evolution of the levant and the eastern mediterranean geophysical data from the levant and the eastern mediterranean suggest that this area can be divided into distinct crustal units of different origins for example a marked difference in crustal structure and structural style exists in the levant between samaria and judea south of the carmel structure and the galilee and lebanon north of it on the other hand several microcontinental fragments such as cyprus and the eratosthenes and anaximander seamounts are embedded within the oceanic crust of the eastern mediterranean the present location of these units has resulted from complex tectonic processes which were active during the mid paleozoic mesozoic evolution of this area during this period several crustal units were accreted to the northern margin of africa while others were detached away from it the crustal evolution of the eastern mediterranean and the levant is intimately linked with the closure of the paleo tethys the formation of the neo tethys and its subsequent closure

complex anisotropy beneath the peruvian flat slab from frequency dependent multiple phase shear wave splitting analysis flat or shallow subduction is a relatively widespread global occurrence but the dynamics remain poorly understood in particular the interaction between flat slabs and the surrounding mantle flow has yet to be studied in detail here we present measurements of seismic anisotropy to investigate mantle flow beneath the peruvian flat slab segment the largest present day region of flat subduction we conduct a detailed shear wave splitting analysis at a long running seismic station nna located near lima peru we present measurements of apparent splitting parameters fast direction and delay time t for sks scs and local s phases from 80 events we observe well defined frequency dependence and backazimuthal variability indicating the likely presence of complex anisotropy forward modeling the observations with two or three layers of anisotropy reveals a likely layer with a trench normal fast direction underlying a layer with a more trench oblique to trench subparallel fast direction in order to further constrain the anisotropic geometry we analyzed the source side splitting from events originating within the slab measured at distant stations beneath the flat slab segment we found trench normal fast splitting directions in the subslab mantle while within the dipping portion of the slab further to the east likely trench subparallel anisotropy within the slab itself this subslab pattern contradicts observations from elsewhere in south america for normal i e more steeply dipping slab conditions it is similar however to inferences from other shallowly dipping subduction zones around the world while there is an apparent link between slab dip and the surrounding mantle flow at least beneath peru the precise nature of the relationship remains to be clarified

deformation along the yammuneh the restraining bend of the dead sea transform paleomagnetic data and kinematic implications a simple geometrical model shows that the plate margin along the restraining bend segment of the transform plate boundary be deformed in order to accommodate overlap of the crust this model predicts both the maximum width of the deformed zone and the magnitude of deformation when the general geometry of the plate margin is known as well as the plate slip vector and the amount of cumulative displacement this idea has been tested along the plate margin of the yammuneh restraining bend of the dead sea transform the plate margin has been deformed by nne folding parallel to the restraining bend and by east west trending right lateral strike slip faults paleomagnetic measurements yield counterclockwise rotation of r r 61 0 9 6 and f f 23 4 17 2 the paleomagnetic rotational data and fault kinematic suggest that the mechanism which accommodates regional left lateral shear is simultaneous right lateral strike slip faulting on secondary faults and block rotation the magnitude of deformation is the same as that predicted by the model which is 100 shortening in a direction parallel to the plate slip vector and negligible deformation in a direction parallel to the transform the large amount of rotation implies that probably more than one fault set is involved and present day seismic activity is the current manifestation of this crustal deformation process if this prediction is correct then the current deformation of the plate margin is accommodated by more favorable newly formed nnw right lateral strike slip faults

constrains on the origin and history of the eastern mediterranean basin abstract the basin formed along the northern passive margin of gondwanaland as a relict of the mesozoic neotethys in early mesozoic time though direct information from the basin itself is meagre the geology of its passive margins and the regional framework of the tethys evolution constrain the formation and history of the basin the eastern mediterranean and its passive margins are interpreted to have formed as a result of several faulting and continental breakup phases from early permian to middle jurassic times before pangaea s complete disintegration this led to the detachment of the eratosthenes and tauride blocks from the margins of the levant and herodotus basins respectively the latter merged in the northeast with the cyprus basin that extended along arabia s northern margin the main rifting probably occurred in the triassic leading to seafloor spreading in the herodotus and cyprus basins while along the levant margin important rifting also occurred in the jurassic during the initial rifting stages extension perpendicular to the levant margin was important but subsequently the tauride block drifted mainly northward the existence of the passive margins and slopes of the eastern mediterranean is documented at least from the end of the middle jurassic until then the basin was probably narrow 200 300 km but during the main phase of the africa laurasia separation it grew to twice its present width or more this scenario depends critically on the interpretation that the tauride block was originally located next to northeastern africa on the western side of the eratosthenes block plate convergence and consumption of the northern portion of the basin have taken place since mid cretaceous times but the active convergent boundary on its northern side formed only in the neogene by modification of earlier structures some intra plate deformation also took place especially in the neogene but it hardly changed the original configuration of the remaining portion of the basin