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evaporites in the extensional section beneath or near to the continental slope where the basinal evaporites have been withdrawn listric and antithetic listric growth faults rollovers and keystone grabens form asymmetric turtleback structures above salt welds and salt rollers further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

the end of the messinian salinity crisis in the western mediterranean insights from the carbonate platforms of south eastern spain abstract how the messinian salinity crisis msc ended is still a matter of intense debate the terminal carbonate complex tcc is a late messinian carbonate platform system that recorded western mediterranean hydrological changes from the final stages of evaporite deposition till the advent of lago mare fresh to brackish water conditions at the very end of messinian times a multidisciplinary study has been carried out in three localities in south eastern spain to reconstruct the history of tcc platforms and elucidate their significance in the msc overall this study provides evidence that the tcc formed following a regional 4th order water level rise and fall concomitant with an opening restriction trend it can be subdivided into four 5th order depositional sequences ds1 to ds4 recording two phases 1 from ds1 to ds3 a tide dominated ooidic to oobioclastic system with stenohaline faunas developed as a result of a 70 m water level rise during this period the tcc developed in a shallow sea with close to normal marine salinity 2 in depositional sequence 4 a microbialite dominated platform system developed this is indicative of a significant environmental change and is attributed to a 30 to 40 m water level fall in the basins under study these restricted conditions were coeval with intense evaporite deformation and brine recycling the syn sedimentary deformation of evaporites had a major impact on platform architecture and carbonate production affecting the messinian series throughout south eastern spain at the end of the tcc history at that time the tcc developed in a lake with fluctuating brackish to hypersaline water these findings suggest a temporary restoration of marine conditions in the western mediterranean marginal basins due to atlantic water influxes prompted by a global sea level rise around 5 6 ma whether marine conditions extended to the entire western mediterranean still needs to be investigated

comparison of prestack stereotomography and nip wave tomography for velocity model building instances from the messinian evaporites velocity model determination during seismic data processing is crucial for any kind of depth imaging we compared two approaches of grid tomography prestack stereotomography and normal incidence point nip wave tomography whereas nip wave tomography is based on wavefield attributes obtained during the common reflection surface stack and thus on the underlying hyperbolic second order traveltime approximation prestack stereotomography describes traveltimes by local slopes i e linearly in the prestack data domain to analyze the impact of the different traveltime approximations and the different input data domains on velocity model building we applied two implementations of these techniques to two profiles of a field marine data set from the levante basin eastern mediterranean because ofthe presence of a thick tabular mobile unit of the messinian evaporites strong vertical and lateral velocity contrasts had been expected the velocity models revealed the reconstruction of high velocity contrasts

tectonics and sequence stratigraphy in messinian basins sicily constraints on the initiation and termination of the mediterranean salinity crisis deposits within the caltanissetta basin of central sicily have been important for developing the desiccating deep basin model for the messinian salinity crisis in the mediterranean linked structural and stratigraphic studies show that the sicilian depocenters are synclines related to underlying thrust structures of the frontal part of the maghrebian chain prior to the salinity crisis these basins were hydrodynamically linked through the foredeep to the mediterranean the precursor sediments terravecchia formation formed a delta sourced from the north early messinian regression acted on a range of paleobathymetries shallow in the north and progressively deeper in the south locally complicated by active thrust structures initial draw down of mediterranean base level is marked across the thrust belt by first cycle carbonates and evaporites on the structural highs and lows respectively vast accumulations of halite and potassium salts up to 1200 m are restricted to growing thrust synclines the different evaporite signatures may be related to different water conditions reflecting various meteoric and marine circulations across various subbasins with cyclicity reflecting high frequency variations in sea level a sequence stratigraphic model is developed to explain fractionation of evaporite facies between different paleobathymetric settings and to predict the temporal evolution of the successions in different subbasins thrusting provides accommodation space for evaporites and also controls the water pathways into the desiccating basins the intra messinian unconformity separating first and second cycle evaporites is a type 1 sequence boundary related to the forced regression associated with the acme of mediterranean desiccation an interpretation supported by local ravinement and incised valley fills the overlying second cycle evaporites are a combination of detrital reworked first cycle material and primary gypsum formed under brackish water regional onlap relationships and bed continuity suggest that this water body was of regional extent with a systematically rising base level these interpretations have several implications for messinian correlations in the mediterranean the deep basin evaporites correlate with an intra messinian unconformity that separates the two cycles on sicily and postdate the first cycle deposits regional base level was largely restored before the end of the salinity crisis

controls on the basinwide architecture of late miocene messinian evaporites on the levant margin eastern mediterranean abstract interpretation of 2d and 3d seismic data from the levant margin eastern mediterranean has revealed the complex depositional and structural setting of the basinwide late miocene messinian evaporites the data set covers a total area of 20 000 km2 permitting a semi regional investigation of the thick up to 1 8 km evaporitic wedge the sequential analysis of time structure maps isochron maps and seismic cross sections highlighted the main morphological and structural features characterizing the pre syn and post evaporitic levant margin this approach provided insights on the impact of local vs regional factors in governing the distribution of the messinian salinity crisis in the region two regional features have been recognized as the most significant controlling factors for the architecture of the messinian evaporites firstly a series of anticlines of the syrian arc foldbelt acted as a structural barrier indirectly governing the overall landward extension of the evaporites secondly submarine canyons active in the area at least since the oligocene afiq el arish and ashdod canyons represented preferential sites of erosion and deposition of evaporites our results document therefore the importance of the deep seated structures and relict drainage for the architecture of the messinian evaporites on the levant margin the new insights provided can be additionally used to infer the original depositional geometry of the evaporites in the study area and as an analogue in other mediterranean areas where 3d seismic is not available yet and sub salt imaging is limited

intra salt deformation implications for the evolution of the messinian evaporites in the levant basin eastern mediterranean abstract we present new evidence of deformation features supporting a multiple deformation phase mechanism of the messinian evaporites through the interpretation of pre stack depth migration psdm seismic data including all intra salt base of salt bs and top of salt ts reflectors the mechanism presented here involves a syn depositional deformation event caused by a nw basin tilting during the last stage of the messinian salinity crisis msc this was followed by post depositional differential sediment loading through radial spreading of the nile cone after the msc inside the evaporite sequence the upper intra salt units may reside in a brittle domain with predominant thrust faults while the lower units in a ductile deformation domain with folds instead a nw flowing channel system is for the first time observed on the ts horizon suggesting a northwestward basin depocenter during the ts formation the observed nnw nne flow of the water bottom wb channels indicates the direction of the current basin depocenter which suggests a dramatic clockwise shift during post messinian a model of the messinian evaporite evolution in the levant basin during the msc has been established the model is based on our observations and the detailed intra salt interpretation and is divided into four stages a the horizontal deposition of all the intra salt units excluding the uppermost unit b the deposition of the uppermost unit and basin nw tilting occurred coevally or sequentially c the ts erosion and the development of nw trending ts channels and d the deposition of post messinian sediments over the evaporite sequence

marine geologic evidence for a levantine sinai plate a new piece of the mediterranean puzzle marine geophysical data recorded offshore egypt illustrate the presence of an active fault belt trending n145 e that obliquely transects the eastern nile deep sea fan this belt more than 150 km long consists of a series of linear transtensive faults with an apparent right lateral horizontal component these fault zones bound thick sediment filled grabens where linear salt ridges and diapirs represent likely messinian salt reactive response to regional transcurrent geodynamics we infer that this tectonic belt might correspond to an offshore extension of the gulf of suez rift system if our hypothesis is correct this fault belt might represent the western boundary of a levantine sinai microplate locked between the major arabia and africa plates and the anatolian aegean microplate

origination and extinction through the phanerozoic a new approach abstract temporal patterns of origination and extinction are essential components of many paleontological studies but it has been difficult to obtain accurate rate estimates because the observed record of first and last appearances is distorted by the incompleteness of the fossil record here i analyze observed first and last appearances of marine animal and microfossil genera in a way that explicitly takes incompleteness and its variation into consideration this approach allows estimates of true rates of origination and extinction throughout the phanerozoic substantial support is provided for the proposition that most rate peaks in the raw data are real in the sense that they do not arise as a consequence of temporal variability in the overall quality of the fossil record even though the existence of rate anomalies is supported their timing is nevertheless open to question in many cases if one assumes that rates of origination and extinction are constant through a given stratigraphic interval then

permian early mesozoic tectonism and continental margin formation in israel and its implications for the history of the eastern mediterranean summary the early mesozoic tectonic reorganization of the tethys region also affected the levant area here two processes were superimposed a the pattern of long wavelength vertical motions of the arabo nubian platform changed in the late permian when israel and nearby areas began to subside b rifting occurred in this subsiding area probably in several phases late anisian and ladinian carnian norian and liassic differential movements reached 2 3 km and magmatism occurred in the liassic and perhaps also in the triassic the tectonism was strongly felt up to 50 km landward of the present coast the crust was thinned and modified under the present continental margin and in the main rifts passive margin conditions were established in late liassic times over the previously faulted area later in the jurassic a carbonate shelf was constructed along this subsiding margin its basinward edge was 1 1 5 km high which shows that the adjacent se mediterranean was already a deep sea hence this basin and its passive margin are considered to have been shaped by the early mesozoic rifting which is recognized in israel the rifting process probably signifies oblique separation of the tauride block from the levant part of gondwana

stress tensor changes related to fluid injection at the geysers geothermal field california 1 studying variations of the stress field in reservoirs caused by massive fluid injection is important toward an improved understanding of geomechanical processes involved we report on spatio temporal variations of the local stress tensor orientation at the geysers geothermal field california we apply two stress inversion methods with detailed uncertainty assessments using a selection of events recorded between 2007 and 2012 our results clearly indicate variations in the orientation of the principal stress axes for the reservoir as a whole showing a normal faulting regime at the reservoir depth between 2 and 3 7 km bounded by a strike slip regime above and below analyzing the temporal evolution of the stress tensor orientation for a prominent seismicity cluster we observe a clear correlation of changes in orientation for 1 3 with the highest injection rates these results suggest that temporal changes in the stress tensor orientation could contribute to characterize reservoirs during stimulation

new age constraints on the evolution of the mt carmel structure and its implications on a late miocene extensional phase of the levant continental margin abstract the mt carmel structure is one of the most prominent topographical elements along the levant continental margin and is the surface expression of a deep tectonic structure the use of 3d seismic data allows us to set new constraints on the uplift of the carmel structure and define the or akiva fault as its southern boundary the or akiva fault was created during a late miocene extensional phase that had also created the carmel fault at the northern edges of mt carmel the different topographic expression across these two boundary faults reflects a change in the post miocene activity where activity along the or akiva fault ceased and its southern side began subsiding whereas its northern side bordered by the carmel fault continued to rise we conclude that the late miocene north south extension previously recognized only along branches of the dead sea transform in northern israel and lebanon affected larger areas than previously thought and can be related to regional kinematic changes during the breakup of arabia from africa and its collision with eurasia

onshore to offshore reconstruction of the messinian erosion surface in western sardinia italy implications for the messinian salinity crisis new outcrops in the sinis peninsula sardinia italy allow a detailed description of the messinian erosion surface the correlation between outcrops industrial seismic data and data collected offshore oristano from a recent cruise permits reconstruction of the geometry of this surface from presently emerged interfluves to the deep canyons offshore with onshore an eroded karstic plateau presently cropping out over a 20 km 5 km area well preserved karst structures occur locally and can form several metres high reliefs the southernmost edge of the plateau is limited by a cliff the karstic plateau and the cliff are sealed by transgressive deposits of pliocene age offshore an interfluve zone with a mostly flat and low angle dipping plateau westward dissected by paleovalleys which were identified down to a depth of 2000 m in the oristano gulf messinian paleovalleys were also identified the capo san marco paleocliff was probably located on the edge of a canyon onshore only one major erosion surface was identified located at the top the messinian sequence offshore this surface extends down to the abyssal plain the surface was emplaced above deposits related to the terminal carbonate complex this indicates that the marginal evaporites are older than the major drawdown of the mediterranean sea level the major drawdown is related to the deposition of the deep evaporites

stress field fluctuations along the dead sea rift since the middle miocene the dead sea transform dst is the suture between the african and the arabian plates both of which subduct northward under the eurasian plate the collision of these plates with eurasia and their relative motion are the source for their internal deformation especially in the vicinity of the dead sea transform geological observations indicate that two distinct paleostrain regimes operated adjacent to the dead sea rift and in the sinai israel subplate 1 wnw shortening less than 10 and nne extension beginning in the turonian is associated with the development of the syrian arc fold belt and attributed to the syrian arc stress field sas and 2 middle miocene to recent nnw shortening and ene extension associated with the 105 km sinistral displacement along the dead sea transform and the opening of the red sea is attributed to the dead sea stress field dss it was originally suggested that the sas terminated during the middle miocene with initiation of the dss however trend and age analysis of many structures shows that formation of sas compatible structures continued after the middle miocene up to the recent in some middle miocene and younger rocks structures such as faults dikes volcanic lineaments and tectonic stylolites compatible with both stress fields were reported in a few locations structures compatible with both stress fields crosscut each other it is suggested that the movements which resulted in the development of the syrian arc and other sas compatible structures are continuing to the recent and that dss movements are superimposed upon them the overlapping of sas and dss structures adjacent to the dst results from spatial and temporal fluctuations in the overall stress state we propose that such variations could be caused by the superposition of large earthquake stress drops associated with movements along the dst on a steady background plate scale stress regime associated with the sas thus dss compatible structures should form in preseismic activity periods when dst related elastic strain is high on the other hand the sas compatible structures should form during interseismic activity times subsequent to large local stress release along the dst

quaternary tectonic patterns along the continental margin of the southeastern mediterranean abstract recently acquired data indicate that the continental margin of the southeastern mediterranean is tectonically active forming two systems of faults the first system includes nw se trending faults that cross the continental margin off israel forming three large and complex structures the dor palmahim and gaza offshore structures the second system includes peripheral faults that follow the eastern outlines of the southeastern mediterranean basin forming a series of shelf break normal faults trending nne ssw off israel a combination of these two systems is found off sinai where nw se trending peripheral faults were encountered it is presumed that the nw se trending faults are rejuvenated miocene faults the present active faulting is associated with the structural evolution of the dead sea rift and the subsidence of the mediterranean basin

quasi dynamic 3d modeling of the generation and afterslip of a tohoku oki earthquake considering thermal pressurization and frictional properties of the shallow plate boundary the generation of the 2011 tohoku oki earthquake has been modeled by many authors by considering a dynamic weakening mechanism such as thermal pressurization tp because the effects of tp on afterslip have not been investigated this study develops a 3d quasi dynamic model of the earthquake cycle to investigate afterslip of the tohoku oki earthquake considering tp and the geometry of the plate boundary we employ several velocity weakening vw patches for mw 7 class events and two large shallow vw patches the frictional properties are set as velocity strengthening vs outside the vw patches the results show that during megathrust earthquakes fast slip propagates to the surrounding vs regions near the vw patches owing to weakening by tp following mw 9 events large afterslips occur in regions below the northern shallow rupture area in the off fukushima region close to the japan trench which is consistent with observations in the vs region near the vw patches during the early afterslip period frictional behavior exhibits less vs with increasing slip velocity due to pore pressure reduction we also consider the frictional properties of the shallow plate boundary fault off tohoku which exhibits a transition from vw to vs from low to high slip velocities the results show the occurrence of slow slip events sses at intervals of a few decades at the shallow plate boundary during megathrust events the vw property at low slip velocity promotes slip along the shallow sse region more than the case with vs property throughout the entire velocity range

the nile deep sea fan an example of interacting sedimentation salt tectonics and inherited subsalt paleotopographic features abstract structural analysis of the nile deep sea fan ndsf indicates that post miocene deformation is largely controlled by down slope movement above a messinian salt layer in contrast to other similar systems the ndsf shows significant lateral asymmetry and three distinct provinces can be recognized regional variations in salt thickness and base salt geometry within the system have led to the presence of structures typical of both gravity gliding and gravity spreading trends of structures within the western and central parts of the ndsf are consistent with forming due to gravity gliding processes this pattern contrasts with that in the eastern ndsf that seem to be much more consistent with deformation due to gravity spreading observed differences in structural style across the ndsf can be related directly to the paleomorphological evolution of the nile cone during messinian time which is perhaps partly related to features that have been inherited from early mesozoic evolution of the north egypt passive margin in the east part of the ndsf the structural evolution has been significantly influenced by the proximity of eratosthenes seamount this large topographic buttress has served to both limit and deflect northeastward allochthonous advance of the messinian evaporites and has thus severely complicated deformation of the overlying plio quaternary sedimentary cover within the broad corridor that runs nnw sse and cuts obliquely across the modern bathymetry of the nile cone

sequence stratigraphy of miocene pliocene carbonate siliciclastic shelf deposits in the eastern mediterranean margin israel effects of eustasy and tectonics abstract mio pliocene marine sediments comprise a discontinuous succession of carbonates and mixed carbonate siliciclastics on the neogene shelf which coincides with the judean foothills area on the slope present mediterranean coastal plain the succession forms a wedge up to 1500 m thick of mostly fine grained siliciclastics the facies and architecture of the succession were influenced both by sea level fluctuation and by the geodynamic change from thermally subsiding passive margins of the arabo african plate to a complex pattern of vertical movements that were associated with the breakup of the plate along the red sea rift and dead sea transform and the convergence of the african arabian and eurasian plates the miocene eustatic succession is highly interrupted by vertical uplift tectonics while the pliocene eustatic succession is well represented despite the limited subsidence rates during most of the early and middle miocene the shelf was tectonically uplifted above sea level except for a short period of flooding in early middle miocene times n8 n9 when sea level rise outstripped the uplift trend and a carbonate platform formed the combination of tectonic uplift and sea level fall prior to late miocene times about 11 m y ago resulted in the incision of a deep beer sheva canyon about 280 m below the shelf plane late miocene sandy marlstones of the bet eshel cycle filled the beer sheva canyon and spilled over it they display a shallowing upward trend resulting in progradational clinoform stacking of the highstand systems tract and channelled debris flows of the forced regression systems tract the messinian desiccation event left the shelf emerged while depositing evaporites on the slope and in the basin the degree of erosion during the messinian was relatively minor because of arid conditions and limited runoff the pliocene shelf shows a very low subsidence rate and compared to the miocene succession is less affected by vertical uplifts the pliocene deposits are divided into six sequences their relative onlap curve largely corresponds to the sequence stratigraphic scheme in sicily and the gulf of mexico the two lowermost sequences i and ii are composed of two sandy units the lower forms an incised valley fill of shoreface deposits in the beer sheva area and offshore sand deposits in distal shelf areas besor although largely eroded sequences i and ii display maximum coastal onlap of all pliocene cycles in the beer sheva canyon area sequence iii consists of mixed carbonate siliciclastic grainstones of shoreface foreshore deposits in the proximal area and lower shoreface deposits in more distal areas sequences iv and v may be considered as a single 3rd order cycle where iv represents regressive lowstand shale and sand deposits and v represents prograding highstand sandy grainstone deposits sequence vi consists of marginal marine to coastal plain marlstones and sands deposits and is largely truncated by the ahuzam conglomerate representing a major uplift phase of latest pliocene to early pleistocene age and marking the permanent emergence of the shelf

decoding the mediterranean salinity crisis this historical narrative traces the steps to unravel over a span of 40 years an extraordinary event in which 5 of the dissolved salt of the oceans of the world was extracted in a fraction of a million years to form a deposit more than 1 million km 3 in volume a buried abyssal salt layer was identified with reflection profiling and sampled during the deep sea drilling project leg 13 the dolomite gypsum anhydrite and halite in the drill cores paint a surprising picture of a mediterranean desert lying more than 3 km below the atlantic ocean with brine pools that shrank and expanded by the evaporative power of the sun the desert drowned suddenly when the gibraltar barrier gave way the explanation of deep basin shallow water desiccation and the notion of a catastrophic zanclean flood had a mixed reception however the hypothesis became broadly accepted following subsequent drilling expeditions nevertheless as experts examined the evaporate facies and sequences of equivalent age in the terrestrial outcrops weaknesses appeared in the concept of repeated flooding and drying to account for the magnitude of the deposits the rosetta stone used to decipher conflicting interpretations turns out not to be the deposits but the erosion surfaces that enclose them these surfaces and their detritus formed in response to the drop in base level during evaporative drawdown extend to the basin floor evaporative drawdown began halfway through the salinity crisis when influx from the atlantic no longer kept up with evaporation prior to that time a million years passed as a sea of brine concentrated towards halite precipitation during the later part of this interval more than 14 cyclic beds of gypsum accumulated along shallow margins modulated by orbital forcing the thick salt on the deep seabed precipitated in just the next few cycles when drawdown commenced and the brine volume shrank upon closure of the atlantic spillway the remnants of the briny sea transformed into salt pans and endorheic lakes fed from watersheds of eurasia and africa the revised model of evaporative concentration now has shallow margin shallow water and deep basin deep water precursors to desiccation

high resolution strontium isotope stratigraphy of the messinian deep mediterranean basins implications for marginal to central basins correlation new 87sr 86sr data from dsdp odp messinian cores from deep mediterranean basins suggest that the usually envisaged correlation of offshore upper evaporites with onshore upper gypsum deposits of sicily cyprus and crete recording the stage 3 5 53 5 33 ma of the messinian salinity crisis may be not entirely correct high resolution stratigraphic calibration of sr isotope data indicates that only a very thin unit commonly 50 m in the uppermost part of the seismic upper evaporites is characterized by the typically lower values for sr isotopes with respect to the global ocean which characterize stage 3 onshore successions lago mare event these deposits mainly consist of interbedded clastic or cumulate gypsum and marls halite recovered from cores in the upper evaporites unit is actually characterized by sr isotope values consistent with stage 2 deposits of onshore successions according to these results the messinian trilogy of the western mediterranean basin could be as a whole correlated with the halite unit of the eastern basin suggesting that different hydrologic conditions characterized the two deep areas during the peak of the salinity crisis

anomalous depth dependency of the stress field in the 2007 noto hanto japan earthquake potential involvement of a deep fluid reservoir 1 we have elucidated depth variations in the stress field associated with the 2007 noto hanto japan earthquake by stress tensor inversion using high quality aftershock data obtained by a dense seismic network aftershocks that occurred above 4 km in depth indicated a strike slip stress regime by contrast aftershocks in deeper parts indicated a thrust faulting stress regime this depth variation in the stress regime correlates well with that in the slip direction derived from a finite source model using geodetic data furthermore the maximum principal stress 1 axis was stably oriented approximately w20 n down to the depth of the mainshock hypocenter largely in agreement with the regional stress field but below that depth the 1 axis had no definite orientation indicating horizontally isotropic stress one likely cause of these drastic changes in the stress regime with depth is the buoyant force of a fluid reservoir localized beneath the seismogenic zone

late miocene sedimentary architecture of the ebro continental margin western mediterranean implications to the messinian salinity crisis the messinian salinity crisis msc resulted from a significant multi phase drop and subsequent reflooding of the mediterranean sea from 5 96 to 5 33 ma well developed drainage networks characterized by step like profiles and abrasion platforms are associated to this event the ebro continental margin western mediterranean presents an additional complexity since the capture of the drainage of the adjacent subaerial ebro basin took place sometime prior to the messinian stage using 3d seismic reflection data this work provides new insights into the origin of the step like profile of the messinian erosional surface mes and timing of the capture of the subaerial ebro basin the results obtained indicate a sedimentary active continental slope and delta progradation during middle late miocene in a normal regressive context associated to a pre messinian proto ebro river the mature development attained by the messinian ebro river network during the msc corroborates that the capture of the ebro basin occurred prior to the msc the configuration of the clinoforms below the mes suggests that deltaic sediments of the messinian paleo ebro river deposited during the tortonian and initial messinian sea level drawdown the mes formed at the top of the tortonian highstand where a fluvial network was deeply carved and in the topset region of the messinian falling stage systems tract where minor erosion occurred fluvial deposits are outstandingly preserved on the main valleys of the mes therefore the step like profile of the mes was not created during zanclean inundation but during the latest stages of the main messinian sea level fall and lowstand

newly recognized eastern extension of the nile deep sea fan a previously unreported easternmost segment of the nile river deep sea fan complex has been identified in the deep levant basin offshore israel based mainly on a recently released high quality three dimensional seismic data set this segment is characterized by densely spaced seabed and subseabed turbidite channel complexes generally fed from the region of the historically active northeastern damietta and pelusian branches of the nile this pattern suggests a previously unnoticeable symmetry in the modern channel distribution between the eastern and western branches of the deep sea fan the base of the nile9s eastern deep sea fan is determined by a nw trending system of pre nile turbidite slope channels at the top of the messinian evaporites the overlying pliocene holocene fan complex is further divided into two distinct stratigraphic units a lower stratified sand rich unit deposited in a basin floor setting and an upper heterogeneous mud rich unit consisting of downslope mass transport and hemipelagic sediments with encased slope channel complexes richer in sand due to gravity gliding and spreading above the underlying thick mobile messinian salt both stratigraphic units as well as the upper part of the messinian salt layer are faulted and folded

record of the messinian salinity crisis in the sw mallorca area balearic promontory spain the current interpretation of the messinian salinity crisis msc involves the deposition of the so called peripheral or marginal evaporites in onshore basins as well as the erosion of the margins and the formation of thick evaporites in the deep parts of the basins the present study focuses on intermediate depth basins i e located between the onshore outcrops and the deep basins indeed the balearic promontory shows small stepped basins filled with msc deposits between its western extremity on the alicante shelf and its eastern end around the menorca block new and already available seismic reflection profiles and onshore data allow us to investigate the nature and geometrical relationships of these deposits in the area between the islands of ibiza and mallorca our observations suggest the existence of three msc related units in this area the lowermost transparent seismic unit can be interpreted as a 100 to 200 m thick salt layer deposited in the deepest part of the central mallorca depression these evaporites pass laterally and upward into a thin bedded seismic unit which could be lithologically equivalent to the upper evaporites of the deep basins all around the borders of the central mallorca depression this bedded seismic unit onlaps a slope unit which shows bedded to chaotic and rafted facies the messinian continental shelf is eroded and incised by a valley extending from the palma onshore area to the mallorca downslope domain our results suggest the presence offshore of at least two generations of diachronous msc deposits the observation of salt on a continental high and the widespread msc deposits on the margins of the central mallorca depression call into question the location of halite preferentially in the deep abyssal basins and the significance of the deep basin msc units that onlap onto the margin erosional surface mes as observed all around the passive margins of the northwest mediterranean basin the dual terminology used for peripheral deep msc evaporites cannot be applied to any of the msc units found in the study area

receiver function images of the distorted philippine sea slab contact with the continental crust implications for generation of the 1891 nobi earthquake mj 8 0 abstract the 28 october 1891 nobi earthquake was one of the largest intraplate earthquakes in japan with an estimated magnitude of 8 0 determined by the japan meteorological agency it occurred in central japan on the eurasian plate beneath which the young philippine sea plate is subducting the geometry of this plate is not smooth rather beneath western japan it appears distorted over a relatively short lateral distance beneath the kinki region of central japan the subduction angle is approximately horizontal and the nobi earthquake occurred just above the horizontal section of the philippine sea slab temporary seismic stations were deployed in this area to investigate local seismic structure and its possible relationship to the cause of the earthquake crustal structure was investigated using receiver function analysis with a spatially dense temporary seismic network a clear image of the subducted philippine sea slab was resolved with ridge like structures beneath the epicentral area of the nobi earthquake the ridge like structure is in contact with the continental crust and the fault plane of the nobi earthquake is located at the edge of one such structure i e in the contact area the unique structure of the area is inferred to cause stress concentration and strain accumulation on local faults which resulted in the large size of the nobi earthquake

change in stress directions along the central denali fault alaska after the 2002 earthquake sequence 1 on the basis of earthquake focal mechanisms the state of stress along the central denali fault alaska system changed after the 2002 earthquake sequence before the earthquake sequence the maximum stress 1 was at a 60 angle with the denali fault west of the point of its maximum curvature fault normal between the fault apex and the totschunda strand and at 50 with respect to the totschunda fault in the epicentral region the post event 1 has rotated counter clockwise along the rest of the rupture zone the sense of rotation is clockwise the 1 direction became nearly fault normal along the totschunda strand along the central part of the rupture 1 is over rotated with 3 being nearly vertical promoting reverse aftershocks this could be an indication of dynamic overshoot

bathymetry of the levant basin interaction of salt tectonics and surficial mass movements abstract a new high resolution bathymetric map of the levant basin between israel and the eratosthenes seamount reveals previously undetected folds faults and channels the map facilitates a regional map view analysis of structures that were previously examined only in cross section the systematic mapping of morpho structural elements in the entire basin is followed by a kinematic interpretation that distinguished between two main processes sculpting the seabed from bottom and top salt tectonics and sediment transport we show that the contractional domain related to salt tectonics is far more complex than previously thought ridges previously interpreted as contractional folds are in fact surficial undulations of the seabed reminiscent of sediment waves moreover other folds previously interpreted as downdip contraction of the westward gliding plio quaternary section are in some parts of the basin caused by updip climbing of this section eastwards as a result of the regional pattern of salt flow away from the nile cone in the context of sediment transport we show that the northern sinai continental slope is covered by a dense net of turbidite channels whereas the levant slope has no channels at all particularly interesting is the levant turbidite channel described and named here for the first time this feature begins at the southeastern corner of the mediterranean at water depths of 1100 m continues along the valley between the sinai and levant slopes and reaches the deepest part of the basin in water depths of 2500 m northeast of the eratosthenes seamount however this prominent feature cannot be explained by the current drainage consisting of two minor rivers that enter the basin at that point and thus most likely reflects periods of wetter climate and or lower sea level when these rivers were more active and possibly connected to the submarine channel system

palaeogeographic implications of the messinian surface in the valencia trough northwestern mediterranean sea abstract sparker 3000 j and 8000 j and multichannel seismic reflection profiles across the valencia trough show a messinian unconformity incised by numerous valleys the main feature of this surface is a large valley that generally underlies the present valencia valley and is deeply entrenched into the miocene deposits the size of this palaeo valley ranges from 0 5 km wide and 15 100 m deep at its western end to 1 6 2 8 km wide and 200 250 m deep downstream an important tributary system is observed with a main canyon 6 8 km wide and 150 200 m deep draining the ebro margin as well as many other smaller valleys draining the catalan and balearic margins downstream other tributaries underlie the present canyons of the catalan margin the location of the tributary system is controlled by the early miocene rift structures the relief of the messinian surface is affected by post miocene deformation that results from salt diapirism extensional faulting and related volcanism late neogene to quaternary volcanic edifices cut the messinian surface and coincide with large residual magnetic anomalies lower pliocene to quaternary salt diapirism in the abyssal plain north of menorca has created a series of structural highs between these highs are deep interdiapiric troughs or basins that have become sediment depocentres during the plio quaternary the complex network of erosional valleys from the valencia trough continental margin demonstrates that the valley system in the basin was not related to the refilling of the mediterranean but to the iberian and balearic margin palaeodrainage that developed during the messinian desiccation the presence of at least three erosional unconformities suggests that there were alternating periods of flooding and retreat of atlantic water during messinian time the messinian subaerial margin with erosional valleys contrasts sharply with the pliocene quaternary marine margin with progradational turbidite systems

multiproxy late quaternary stratigraphy of the nile deep sea turbidite system towards a chronology of deep sea terrigeneous systems abstract understanding the recent formation of a sedimentary system such as a deep sea turbidite system dsts requires an accurate stratigraphic control on deposits due to the important terrigeneous input which disrupts the sedimentary record dsts is an environment where stratigraphic control is difficult to assess most of the time traditional stratigraphic tools are not accurate enough this has led to a rather limited number of studies concerning stratigraphy in dsts in this study we examine several hemipelagic long piston cores collected from the nile dsts eastern mediterranean in order to understand the recent evolution of the complex sedimentary system in this area the first aim of this study is to show how to obtain a reliable timeframe in dsts indeed we provided a detailed ecostratigraphical scheme based on planktonic foraminiferal distribution oxygen isotope records and lithostratigraphy sapropels and tephra of three cores where the sedimentation is least disturbed we have identified 29 foraminiferal ecozones during the last 250 000 years bp with an approximately 2000 year time resolution the time span of each ecozone was constrained by the oxygen isotope record 14 c ams radiometric data tephrochronology and the sapropel chronology these high resolution ecostratigraphical time subdivisions have been applied in discontinuous mixed hemipelagic turbiditic sequences of a levee record this example shows how to date gravity events formation and time periods of sedimentary accumulations

historical and pre historical tsunamis in the mediterranean and its connected seas geological signatures generation mechanisms and coastal impacts abstract the origin of tsunamis in the mediterranean region and its connected seas including the marmara sea the black sea and the sw iberian margin in the ne atlantic ocean is reviewed within the geological and seismotectonic settings of the region a variety of historical documentary sources combined with evidence from onshore and offshore geological signatures geomorphological imprints observations from selected coastal archeological sites as well as instrumental records eyewitnesses accounts and pictorial material clearly indicate that tsunami sources both seismic and non seismic e g volcanism landslides can be found in all the seas of the region with a variable tsunamigenic potential local regional and basin wide tsunamis have been documented an improved map of 22 main tsunamigenic zones and their relative potential for tsunami generation is presented from west to east the most important tsunamigenic zones are situated offshore sw iberia in the north algerian margin in the tyrrhenian calabria and messina straits in the western and eastern segments of the hellenic arc in the corinth gulf of central greece in the levantine sea offshore the dead sea transform fault and in the eastern side of the marmara sea important historical examples including destructive tsunamis associated with large earthquakes are presented the mean recurrence of strong tsunamis in the several basins varies greatly but the highest event frequency 1 96 years is observed in the east mediterranean basin for most of the historical events it is still unclear which was the causative seismic source and if the tsunami was caused by co seismic slip by earthquake triggered submarine landslides or by a combination of both mechanisms in pre historical times submarine volcanic eruptions i e caldera collapse massive pyroclastic flows volcanogenic landslides and large submarine landslides caused important tsunamis although little is known about their source mechanisms we conclude that further investigation of the tsunami generation mechanisms is of primary importance in the mediterranean region inputs from tsunami numerical modeling as well as from empirical discrimination criteria for characterizing tsunami sources have been proved particularly effective for recent well documented aseismic landslide tsunamis e g 1963 corinth gulf 1979 cote d azur 1999 izmit bay 2002 stromboli volcano since the tsunami generation mechanisms are controlled by a variety of factors and given that the knowledge of past tsunami activity is the cornerstone for undertaking tsunami risk mitigation action future interdisciplinary research efforts on past tsunamis are needed

some depositional patterns at continental margin of southeastern mediterranean sea the upper miocene to holocene sedimentary strata in the continental margin of the southeastern mediterranean sea depict two depositional regimes the upper miocene sequence is predominantly evaporitic and forms the southeastern portion of the upper miocene evaporites present throughout the mediterranean region the pliocene quaternary sequence is predominantly detrital and its major source of sediments has been the nile river interpretation of data derived from several multichannel seismic profiles suggested facial variations in the upper miocene and the pliocene pleistocene formations two depositional facies of the upper miocene evaporites indicating basinal and shelf depositional environments were found statistical analyses show correlations of the thickness of the evaporites with their interval seismic velocity their depth and the present bathymetry indicating the autochthonous characteristics of the sequence the basinal and the shelf depositional facies are separated by a transition zone that trends nne ssw and is associated with faulting it is suggested that this zone commonly known as the pelusium line was the shelf edge zone during the late miocene facial analysis of the data pertainin to the pliocene pleistocene sequence depicts its allochthonous characteristics statistical negative correlation was calculated between the distance from the continental shelf and the thickness of this sequence indicating its detrital origin variations in thicknesses of both formations compared with the bathymetric depths suggest a post miocene subsidence of the southeast mediterranean basin

the western tyrrhenian sea revisited new evidence for a rifted basin during the messinian salinity crisis abstract in the last fifty years the messinian salinity crisis msc has been widely investigated in the mediterranean sea but a major basin remains fewly explored in terms of msc thematic the western tyrrhenian basin the rifting of this back arc basin is considered to occur between the middle miocene and the early pliocene thus including the msc giving a unique opportunity to study the crisis in a context of active geodynamics however the msc seismic markers in the western part of the tyrrhenian sea have only been investigated in the early eighties and the msc event in the western tyrrhenian basin remains poorly studied and unclear in this study we revisit the msc in the western tyrrhenian basin i e along the eastern sardinian margin we present results from the interpretation of a 2400 km long hr seismic reflection dataset acquired along the margin during the metyss research cruises in 2009 and 2011 the maps of the msc seismic markers reveal that the eastern sardinian margin was already dissected in structurals highs and lows during the msc we also demonstrate that the msc markers constitute powerfull time markers to refine the age of the rifting which ended earlier than expected in the east sardinian basin and the cornaglia terrace these results allow us to discuss the palaeo water depth of the western tyrrhenian basin during the msc as well as implications for possibles scenarios of the messinian salinity crisis across the eastern sardinian margin

the durations of silurian graptolite zones recently published radiometric data show the duration of the silurian period to be approximately 32 ma significantly longer than previous estimates radiometric and graphic correlation studies demonstrate considerable variation in the durations of the four silurian epochs approximately 13 ma for the llandovery 4 ma for the wenlock 5 ma for the ludlow and 10 ma for the p idoli using this new geochronological data figures for average graptolite zone duration are presented for each epoch ranging from as little as 0 44 ma in the wenlock to 1 43 ma in the p idoli the figures provide a refined subdivision of the silurian timescale of value to studies which use silurian graptolite zones to calibrate geological processes

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

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

rapid strand plain accretion in the northeastern nile delta in the 9th century a d and the demise of the port of pelusium an unusually large 1 km 3 and rapid influx of nile river sediment in the early 800s a d resulted in accretion of an extensive strand plain 6 to 15 m thick 35 km long and as much as 12 km wide on the subsiding northeastern nile delta margin egypt this event is related to blockage of the pelusiac branch and breaking through of a new distributary to the west of present day port said probably representing initiation of the damietta branch the sand is of analytically identical age throughout the area and was deposited within less than 60 yr as indicated by 14 c and amino acid racemization analyses of donax shells from a series of cores radiocarbon dates in combination with historical accounts by al jakubi who found the strand plain already in existence when he visited the area in the late 800s place this event in the early 800s nilometer flood records suggest that the sequence of great floods of 813 816 and 820 may have been the triggering events this sudden displacement of sand caused pelusium then the principal port and fortified city of the northeastern nile delta located at the mouth of the pelusiac branch to be cut off from both the nile and the mediterranean and led to its decline and eventual abandonment by the 12th century when the crusaders arrived

high resolution early paleozoic ordovician silurian time scales for much of the geologic time scale resolving power appears to be limited by the duration of biostratigraphic zones and subzones yet these zones exploit the appearance and disappearance events of only a small fraction of the species they span computer algorithms can sequence an order of magnitude more events and make explicit the uncertainties that arise when calibrating the resulting time line an illustrative case history builds an ordovician and silurian time scale from the geologic record of the entire graptolite clade over 1900 species from more than 400 localities and sections worldwide the same approach can be applied to any stratigraphic interval with detailed biostratigraphic observations it provides the foundation for time scales and paleobiologic time lines using logic similar to graphic correlation optimizing algorithms search for a composite sequence of species first and last appearance events that minimizes the implied shortcomings of all the field observations the algorithms minimize the number of species coexistences that are implied but never observed and the net adjustments needed to bring local range charts into agreement with a single composite sequence of events after total section thicknesses have been rescaled to help normalize for variation in depositional rate mean stratigraphic thicknesses are used to scale the intervals between adjacent events in the composite sequence the resulting scaled composite sequence is converted to a relative geologic time scale by identifying stage and zone boundaries within the sequence of graptolite events this relative scale is in turn calibrated by dated volcanic ash beds that were incorporated in the search for the optimal sequence these dated events are also used to test for linearity of the scaled composite the final time scale has a potential resolving power of 0 02 0 1 m y more than ten times better than can be achieved by traditional zones graptolite zones vary widely in duration from as short as 0 1 m y to nearly 5 0 m y the mean duration of zones or zonal groupings calibrated here is 1 44 m y in the ordovician and 0 91 m y in the silurian the average uncertainty in locating zone boundaries in a single composite sequence is about one fourth of the mean zone duration the variance resulting from differences in time scales developed from differing numbers of field observations and in response to changes in the optimization criteria gives a very conservative measure of the overall robustness of the method these differences indicate an average uncertainty in the age of graptolite zone boundaries that is more nearly equal to the mean zone duration for zone duration the mean uncertainty amounts to about one half of the length of an average zone

messinian subaerial erosion of the proto nile delta abstract the evaporitic drawdown and subsequent dessication of the mediterranean basins during the messinian salinity crisis has been confirmed by detailed seismic mapping of the ensuing erosion surface in the nile delta region the basal messinian unconformity determined by seismic analysis and borehole correlation extends from almost sea level in the southern delta area to depths of at least 5 km in the nile cone the onlap of the contemporaneously deposited fluvio deltaic clastics of the qawasim formation occurs at between 2 5 to 4 km below present gradual initial drawdown of the mediterranean sea with occasional sudden sporadic falls is implied by the presence of entrenched meanders and impaired rejuvenation terraces in the nile canyon formed as the proto nile river cut down into the pre existing tortonian delta complex the former tortonian delta slope became an extensive linear erosional front with over 3 km of vertical relief the uppermost levels of which were protected by tabular oligocene basalt flows preserved as mesas and buttes the lower slopes were the site of coalescing piedmont fans fed by upper slope wadi systems the piedmonts merged into the qawasim fluvio deltaic deposits of the proto nile fluvial flood plain the subcrop beneath the basal messinian unconformity reveals a remarkable diversity of rock type each with its own distinctive control on the geomorphology and geometry of the ensuing messinian erosional surface fracture patterns within the oligocene basalts produced a trellis drainage network which became later captured by a dendritic system developed on less resistant prodelta shales of the former tortonian delta slope close study of seismic profiles clearly demonstrates that the basal messinian erosional disconformity can be traced northwards to depths of at least 2 5 3 0 km before becoming affected by later pliocene faulting this validates a deep dessication model for the evolution of the messinian evaporites

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

the mediterranean messinian salinity crisis an apennine foredeep perspective abstract owing to its expanded stratigraphic sections the apennine thrust belt offers the opportunity to better understand the evaporitic and post evaporitic messinian events a physical stratigraphic framework of messinian deposits based on facies analysis and basin wide correlation of key surfaces and sedimentary cycles is presented it is shown that the messinian apennine foredeep had marginal basins with shallow water primary evaporites and deeper basins where resedimented evaporites accumulated under relatively deep water conditions like many other mediterranean examples primary shallow water evaporites of apenninic marginal basins show evidence for subaerial exposure and erosion however the development of such an erosional surface does not correspond to the deposition of primary evaporites in the deepest part of the basin s here the unconformity can be traced towards the base of resedimented evaporites or to a level within them implying that the deeper basins of the apennine foredeep never underwent desiccation during the messinian salinity crisis but rather received the eroded marginal evaporites this fact usually overlooked raises important questions about the deep desiccation model of the mediterranean

chronology causes and progression of the messinian salinity crisis the messinian salinity crisis is widely regarded as one of the most dramatic episodes of oceanic change of the past 20 or so million years 1 3 earliest explanations were that extremely thick evaporites were deposited in a deep and desiccated mediterranean basin that had been repeatedly isolated from the atlantic ocean1 2 but elucidation of the causes of the isolation whether driven largely by glacio eustatic or tectonic processes have been hampered by the absence of an accurate time frame here we present an astronomically calibrated chronology for the mediterranean messinian age based on an integrated high resolution stratigraphy and tuning of sedimentary cycle patterns to variations in the earth s orbital parameters we show that the onset of the messinian salinity crisis is synchronous over the entire mediterranean basin dated at 5 96 0 02 million years ago isolation from the atlantic ocean was established between 5 59 and 5 33 million years ago causing a large fall in mediterranean water level followed by erosion 5 59 5 50 million years ago and deposition 5 50 5 33 million years ago of non marine sediments in a large lago mare lake sea basin cyclic evaporite deposition is almost entirely related to circum mediterranean climate changes driven by changes in the earth s precession and not to obliquity induced glacio eustatic sea level changes we argue in favour of a dominantly tectonic origin for the messinian salinity crisis although its exact timing may well have been controlled by the 400 kyr component of the earth s eccentricity cycle

3d seismic analysis of circular evaporite dissolution structures eastern mediterranean buried circular collapse structures above a tabular evaporitic body are recorded by recently acquired 3d seismic data on the levant basin and continental margin offshore israel eastern mediterranean the structures formed during the pliocene as buried messinian late miocene evaporites underwent extensive dissolution in a submarine deep water setting three dimensional seismic analysis is used to describe the detailed morphology of the structures and the associated overburden allowing the reconstruction of their origin and development it is proposed that evaporite dissolution led to the collapse of the weakly lithified overburden and this deformed with a series of concentric extensional faults from the structural analysis of the overburden the estimated maximum duration of the dissolution event is 0 75 1 ma the mechanism proposed for the creation of the circular collapse structures is subjacent dissolution of the more soluble evaporites in the messinian evaporites as a result of focused vertical fluid flow at the base of the evaporitic series rapid release of overpressured fluids as for example during an earthquake is thought to have initiated the focused fluid flow which impinged on the evaporitic seal to the point where dissolution occurred creating the localized circular collapse structures in the overburden

intra to post messinian deep water gas piping in the levant basin se mediterranean abstract this study presents evidences for fluid flow manifested as pipe structures in the post evaporitic overburden characterised from a 3d seismic data from the levant basin offshore central israel interestingly these pipes are genetically and spatially contextualized east and west of the study area all rooted in the messinian evaporite substratum pipes in the western group accounts for 83 of the pipe population are crudely cylindrical oval to elliptical in planform with diameter and height ranging 350 2000 m and 320 420 m respectively internal configurations within this group varies from chaotic to concave upward reflections diagnostic of fluid induced collapse pipes in the eastern group are seepage pipes appearing conical in shape with height of 350 510 m and diameter of 320 420 m the eastern group pipes are characterized by lack of internal reflectivity and or disrupted stratal reflections the western group indicates an episode of fluid flow till the mid pliocene compared to late pliocene in the eastern group a conceptual model for the pipes in the western group is proposed to have occurred from subjacent dissolution of the messinian evaporite under deep water marine conditions during the pliocene by vertically focused fluid flow from intra messinian realm dissolving the top evaporites and inducing systematic collapse in the overburden the onset of which may have been triggered by seismicity conversely pipes in the eastern group are proposed to have developed from breaching the top evaporite by pressurized fluids that developed from lateral pressure transfer due to differential loading of the overburden and salt tectonics these pipe structures may pose a potential risk to deep water exploration and development the fluid expulsion phenomena documented in this study has wider implications for the hydrodynamics of many basins where thick evaporite layers are widely developed

did the mediterranean sea dry out during the miocene a reassessment of the evaporite evidence from dsdp legs 13 and 42a cores abstract the idea that the mediterranean sea dried out completely during the late miocene messinian 5 6 ma is now widely accepted this idea first published in 1972 hsu 1972a hsu 1972b grew out of the interpretation by deep sea drilling project dsdp scientists that the evaporites recovered from beneath the floor of the mediterranean by drilling on dsdp legs 13 1970 and 42a 1975 were of shallow water origin since that time there have been a number of advances in understanding of evaporite depositional processes and with this in mind we have reexamined the evidence provided by the dsdp evaporite cores we show that the case for deposition of the miocene evaporites of the sub mediterranean under shallow water conditions is based on interpretations that are either equivocal or incorrect several features of these evaporites used by the dsdp workers as evidence of shallow water conditions are more compatible with deposition under deep water below wave base conditions and others can only be considered as of uncertain origin in addition coring has sampled only the upper few tens of meters of the evaporites a factor that seriously limits any interpretation of the origin of the deposit as a whole in view of these findings we suggest that the question of the origin of the miocene evaporites beneath the floor of the mediterranean sea be reexamined by the geologic and oceanographic communities

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

graptoloid evolutionary rates track ordovician silurian global climate change graptoloid evolutionary dynamics show a marked contrast from the ordovician to the silurian subdued extinction and origination rates during the ordovician give way during the late katian to rates that were highly volatile and of higher mean value through the silurian reflecting the significantly shorter lifespan of silurian species these patterns are revealed in high resolution rate curves derived from the conop constrained optimization scaled and calibrated global composite sequence of 2094 graptoloid species the end ordovician mass depletion was driven primarily by an elevated extinction rate which lasted for c 1 2 ma with two main spikes during the hirnantian the early silurian recovery although initiated by a peak in origination rate was maintained by a complex interplay of origination and extinction rates with both rates rising and falling sharply the global 13 c curve echoes the graptoloid evolutionary rates pattern the prominent and well known positive isotope excursions during the late ordovician and silurian lie on or close to times of sharp decline in graptoloid species richness commonly associated with extinction rate spikes the graptoloid and isotope data point to a relatively steady marine environment in the ordovician with mainly background extinction rates changing during the katian to a more volatile climatic regime that prevailed through the silurian with several sharp extinction episodes triggered by environmental crises the correlation of graptoloid species diversity with isotopic ratios was positive in the ordovician and negative in the silurian suggesting different causal linkages throughout the history of the graptoloid clade all major depletions in species richness except for one were caused by elevated extinction rate rather than decreased origination rate

erosional processes and paleo environmental changes in the western gulf of lions sw france during the messinian salinity crisis abstract current interpretation of the messinian salinity crisis msc involves partial desiccation of the mediterranean sea coupled with the deposition of thick evaporites in the deep basins new sets of seismic reflection profiles in the western part of the gulf of lions confirm the basinward extension of the messinian erosion and enable the mapping of distinctive seismic markers indicating the messinian erosional surface or messinian unconformity the basin margin detrital deposits and the deep evaporite sequence the geometrical relationship between these three elements and their relationship to the paleogeography of the margin during the msc provide new information about the evolution of the study area during the messinian the messinian erosional surface mes commonly correlated with the desiccation phase and the deposition of deep evaporites during the apogee of the event is generally interpreted as a subaerial feature in the gulf of lions it is a complex diachronic polygenic erosional surface observed at the base of the prograding plio quaternary sequence beneath the shelf and slope it extends downslope beneath the deep basin upper evaporites and the salt and possibly correlates conformably with the base of the so called deep lower evaporites the whole morphology of the mes reflects a buried drainage pattern supporting the interpretation of fluvial erosion driven by a substantial drop in sea level our results also suggest that large submarine gravity flows occurred prior to any significant accumulation of salt in the basin and prior to the upper evaporites consequently interbedded clastic deposits may partly account for the parallel reflectors of the lower evaporites since river erosion persisted throughout the msc the salt and upper evaporite units may also contain a large amount of detrital sediments the good quality of the new seismic data clearly reveals fan shaped messinian deposits in the downstream part of the main messinian valleys i e the nile var and spanish rivers the depositional scenarios generally involve a substantial sea level fall coupled with deltaic prodeltaic accumulations a chaotic seismic unit unit d filling messinian lows and extending beneath the salt within the study area is interpreted as a messinian clastic unit we propose a polyphase scenario of detrital fan deposition involving pre syn and post salt deposition in subaqueous subaerial environments in the gulf of lions a late miocene tectonic phase that affected the western shelf also played an important role in controlling a the pattern of the messinian fluvial network b the location of maximum erosion on the shelf and c the location of the detrital fan depocentre downslope

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

pacing of paleozoic macroevolutionary rates by milankovitch grand cycles periodic fluctuations in past biodiversity speciation and extinction have been proposed with extremely long periods ranging from 26 to 62 million years although forcing mechanisms remain speculative in contrast well understood periodic milankovitch climate forcing represents a viable driver for macroevolutionary fluctuations although little evidence for such fluctuation exists except during the late cenozoic the reality magnitude and drivers of periodic fluctuations in macroevolutionary rates are of interest given long standing debate surrounding the relative roles of intrinsic biotic interactions vs extrinsic environmental factors as drivers of biodiversity change here we show that over a time span of 60 million years between 9 and 16 of the variance in biological turnover i e speciation probability plus species extinction probability in a major early paleozoic zooplankton group the graptoloids can be explained by long period astronomical cycles milankovitch grand cycles associated with earth s orbital eccentricity 2 6 million years and obliquity 1 3 million years these grand cycles modulate climate variability alternating times of relative stability in the environment with times of maximum volatility we infer that these cycles influenced graptolite speciation and extinction through climate driven changes to oceanic circulation and structure our results confirm the existence of milankovitch grand cycles in the early paleozoic era and show that known processes related to the mechanics of the solar system were shaping marine macroevolutionary rates comparatively early in the history of complex life we present an application of hidden markov models to macroevolutionary time series and protocols for the evaluation of statistical significance in spectral analysis

imaging the seismic structure and stress field in the source region of the 2004 mid niigata prefecture earthquake structural zones of weakness and seismogenic stress concentration by ductile flow 1 we deployed a dense temporal seismic network in the source region of the 2004 mid niigata prefecture earthquake thrust fault japan a detailed velocity structure and accurate aftershock distributions were elucidated by inverting aftershock arrival times using double difference tomography a stress tensor inversion using the first motion data was also conducted in order to investigate the stress field the seismic velocities in the hanging wall above the main shock fault are lower than those in the footwall with the velocity contrast extending to a depth of approximately 10 km the aftershocks along the main shock rupture zone are distributed around the sharp boundary between the low and high velocity bodies furthermore aftershocks associated with the largest aftershock appear to be aligned on a boundary between low and high velocity zones in the footwall the orientation of maximum principal stress 1 is consistent with the regional compressional strain rate axis inferred from gps data except in the southwestern side of the main shock hypocenter where the azimuth of 1 rotates approximately 20 counterclockwise the main shock hypocenter was located roughly at the transition zone where the structure of the hanging wall changes laterally and the azimuth of 1 rotates heterogeneous structures of the seismic velocity and the stress field combined with the ductile deformation of the upper crust may have concentrated seismogenic stress around the hypocenter area to cause the complex distributions of aftershock sequence on structural boundaries

step like migration of early aftershocks following the 2007 mw 6 7 noto hanto earthquake japan seismic data reveal that the aftershock zone expands with time after a main shock event here we examine the aftershock sequence recorded during the first 32 days following the 2007 noto hanto earthquake japan by applying a matched filter technique to the data we detected about 10 times more events than those listed in the routinely constructed earthquake catalog the aftershock area expanded along the fault strike as a logarithmic function of time beginning immediately after the main shock aftershock expansion toward the sw was especially extensive and developed more rapidly than toward the ne interestingly the aftershock area expanded in a step like manner by the activation of a series of spatially clustered seismic bursts spatial correlation between the aftershock extension and the afterslip distribution suggests that the expansion of the aftershock area could be mainly driven by aseismic afterslip the aftershock area continues to expand even though 7 years have now passed since the main shock

diversion and morphology of submarine channels in response to regional slopes and localized salt tectonics levant basin abstract in the levant basin submarine channels are abundant around the nile deep sea fan ndsf an area which is also affected by salt tectonics related to the messinian salt giant here we focus on the relationship between submarine channels and obstacles formed by salt tectonics initially we use methods developed for terrestrial morphological analysis and quantify channel sinuosity width and slope in search for consistent relationships between morphometric parameters and channel response to obstacles however this traditional analysis did not yield robust conclusions then we apply two new morphometric parameters suggested here to express the distortion of channels by obstacles incident angle defined as the acute angle between the regionally influenced channel direction and the strike of the tectonic obstacle and diversion angle defined as the angle between the direction of the regional bathymetric slope and the average direction of the channel these parameters illustrate the influence of the regional scale basin geometry and the superimposed tectonic influenced seabed patterns on channel development we found hyperbolic relationships between incident angle and diversion angle in which channels flowing approximately parallel 0 to tectonic folds are obviously not diverted channels nearly orthogonal 90 to obstacles crosscut them right through and again not diverted much in contrast channels with a general direction diagonal to the obstacles 40 are diverted by ten degrees 10 this diversion accumulates along large distances and significantly influences the regional development of channels around the ndsf noteworthy this phenomenon of channel diversion indirectly deteriorate normal slope sinuosity relationships known from terrestrial studies in light of these findings we suggest that these new parameters can be applied to other basins where submarine channels interact with seabed obstacles

post messinian evolution of the southeastern levant basin based on two dimensional stratigraphic simulation abstract the evolution of the southeastern levant basin following the messinian salinity crisis was interpreted using observations derived from seismic sections and well data and from output of a two dimensional forward stratigraphic simulation program sedpak the working assumption was that the thick evaporitic messinian sequence was generated in a shallow water albeit a topographically deep basin the sea level dropped at least 800 m below its present level and may have been as low as 1300 m the latter value representing the reconstructed depth of the top messinian in the deep part of the basin the top of the evaporitic sequence in that part of the basin was virtually horizontal at the end of the messinian crisis and thus may be used as a regional datum subsidence rates measured for the shelf and coastal plain of israel indicate a reduction of these rates for the pleistocene when compared to the pliocene during the pleistocene subsidence rates for the base slope increased and dictated the modern physiography of the margin earlier in the middle to late pliocene small scale salt movements occurred in the deep basin producing the fragmented and irregular shape of the m horizon the seismic event marking the top of the evaporitic sequence and deforming the overlying pliocene section the simulated rate of sediment supply indicates a constant increase over time for the pliocene and the pleistocene probably in response to an increased influx of nile derived along shelf sediment transport

reactivation of ancient rift systems triggers devastating intraplate earthquakes 1 large historical and recent intraplate earthquakes have been concentrated along a contractional zone at the eastern margin of the japan sea back arc basin here we present high resolution three dimensional tomographic imaging of seismic velocities in this zone using data from a dense seismograph deployment we discover that stepwise and tilted block structures of the basement which are geophysical evidence of a miocene rift system are widely distributed beneath the thick sedimentary basin most aftershocks following recent intraplate earthquakes align roughly along the tilted block boundaries and are controlled by weaknesses associated with buried rift systems furthermore slow anomalies are localized beneath the seismogenic zones suggesting that fluids may have locally weakened the strength of the lower crust we propose that stress loading through ductile creeping of the weak lower crust reactivates pre existing weak faults within ancient rift systems leading to devastating intraplate earthquakes

the buried afiq canyon eastern mediterranean israel a case study of a tertiary submarine canyon exposed in late messinian times abstract the afiq submarine canyon was one of a series of canyons initially incised in a drowned shelf edge and slope of the eastern mediterranean margins in early oligocene times p19 zone during most of the early miocene submarine erosion or non deposition prevailed this was followed by deposition of pelagic marls and debris flows in early middle miocene n8 times large scale sliding in late middle miocene times n14 resulted in the collapse of the slope the removal of most of the middle miocene sequence and the formation of a box shaped scar back cutting incision ultimately resulted in the incision of the shelf in late miocene times a sea level fall ranging between 50 and 800 m below the canyon s rim resulted in the deposition of the messinian lower evaporites mavqiim formation within the canyon a subsequent rise of a similar extent led to the deposition of the upper evaporites be eri gypsum which are found on the canyon s southern shoulder the final messinian sea level drop below the canyon s floor resulted in a subaerial environment in the canyon the erosion of the upper evaporites and the subsequent deposition of fluvial and brackish sediments afiq formation the latter correspond to the lago mare sediments known throughout the mediterranean the rapidly rising sea level during the pliocene along with the high rate of nilotic clastic sedimentation resulted in the final burial of the afiq canyon and a pronounced seaward progradation 20 30 km of the shelf edge

alternate interpretation of the messinian salinity crisis controversy resolved a high resolution chronology of the mediterranean messinian salinity crisis is proposed two types of evaporite deposition may be distinguished those in marginal areas vs those in basinal ones their diachroneity is deduced from the stratigraphic relationships linking these evaporites to a major messinian erosional surface a two step model is proposed for the evolution of the salinity crisis through time during the first phase from 5 75 to 5 60 ma the deposition of marginal evaporites took place in response to a modest sea level fall in the second interval from 5 60 to 5 32 ma the mediterranean basin became isolated during this later period the deposition of basinal evaporites and the cutting of the mediterranean canyons took place

recent depositional patterns of the nile deep sea fan from echo character mapping the nile deep sea fan was surveyed in 1998 using swath multibeam bathymetry backscatter imagery and 3 5 khz and seismic profiling on the basis of this new data set the fan has been divided into three main provinces western central and eastern recent sedimentary patterns as deduced from echo character mapping show that gravity induced sedimentary deposits are predominant and are expressed through either slides debris flows or turbidites turbidity processes are particularly active in the westernmost province through a well developed network of deep sea channels this network controls turbiditic flows that subsequently overflow levees mass wasting processes are extremely efficient all over the nile deep sea fan in the upper central province a broad allochthonous tongue of mass flow deposits generated by slope destabilizations may have led to channel avulsions and migrations in the eastern province a northwest southeast deformed belt resulting from combined deep seated and salt related tectonics contains large proportions of destabilized sediments i e originating from destabilization processes such as mass movements probably settled by recent tectonic activity this article highlights 1 the influence of both thin skinned and thick skinned tectonics on sedimentary distribution and 2 the predominance of gravity induced sediments turbidites slides and mass flows in such submarine fans the distribution of debris flows and sedimentary deposits settled by turbidity currents appears fundamental in predicting reservoir geometry and economic potential

direct inversion of earthquake first motions for both the stress tensor and focal mechanisms and application to southern california in inverting populations of focal mechanisms to estimate stress misfits may arise owing to 1 errors in determining the fault plane solutions and 2 real variations in the state of stress among a number of techniques that invert for stress most effectively regard only the latter and only indirectly describe the former through statistical means so make it difficult to differentiate real stress variations from noisy data ambiguity arises because realistic methods for determining focal mechanisms for small earthquakes depend on p wave first motions in a highly nonlinear manner which is difficult to propagate into stress inversions to address these issues we present a new method for constraining stress tensors in which first motion observations are directly inverted for stress without assuming that focal mechanisms are known the technique produces estimates of four stress parameters a suite of focal mechanisms consistent with both the stress tensor and the first motions and estimates of the uncertainty in stress it also provides a natural test of the stress homogeneity hypothesis and a means to identify those earthquakes whose first motions are not consistent with a homogeneous stress tensor when tested against artificial data the method correctly recovers input stresses and yields uncertainties that depend upon both data distribution and reliability of first motion picks as expected utilizing first motions from the southern california catalog the method is applied to several clusters and aftershock sets from 1981 to 1992 typical uncertainties in stress orientation exceed 20 30 at the 95 confidence level resulting from 5 mispick rates typical of even the cleanest data these uncertainties exceed some previous estimates for similar populations presumably because they account for focal mechanism un certainties and perhaps indicating that some previously reported stress variations are not statistically significant most populations are found to be internally consistent with a homogeneous stress field the most significant exceptions being aftershock sequences of some major earthquakes in at least one case the 1992 landers sequence aftershocks at the north end of the rupture zone appear to reflect exceedingly heterogeneous stresses overall the method provides a useful and robust approach for evaluating stress constraints provided by p wave first motions

crustal stress field in southern california and its implications for fault mechanics we present a new high spatial resolution image of stress orientation in southern california based on the inversion of earthquake focal mechanisms we use this image to study the mechanics of faulting in the plate boundary region the stress field contains significant spatial heterogeneity which in some cases appears to be a result of the complexity of faulting and in other cases appears to be a cause temporal changes in the stress field are also observed primarily related to major earthquakes the observed 15 10 rotation of the stress axes due to the 1992 m7 3 landers mainshock implies that the deviatoric stress magnitude in the crust is low of the order of 10 mpa this suggests that active faults in southern california are weak the maximum principal stress axis near the san andreas fault is often at 50 to the fault strike indicating that the shear stress on the fault is comparable to the deviatoric stress the san andreas in southern california may therefore be a weak fault in a low strength crust

late tertiary structure and stratigraphy of north sinai continental margin new seismic data provide information on the structural development and late tertiary stratigraphy of the continental slope and rise off northern sinai the upper continental slope is characterized by a marginal plateau composed of a series of platforms or steps the lower continental slope is smooth except for a low ridge paralleling the western part numerous diapiric structures along the continental margin north of the sinai peninsula emerge from an evaporitic layer of late tertiary age the diapirs usually are aligned along west northwest trending faults a salt ridge 90 km long produces a submarine ridge in the lower continental rise two main fault trends have been mapped in the western part of the continental margin they trend west northwest and in the eastern part northeast these trends parallel the continental slopes of northern sinai and southern israel respectively the structural grain of the sinai margin appears to be controlled by two main tectonic elements 1 rejuvenated basement faults of the continent ocean transition zone and 2 salt diapirism due to loading of messinian evaporites with nile derived upper tertiary clastics

salt tectonics and mud volcanism in the latakia and cyprus basins eastern mediterranean salt tectonics and mud volcanism in the latakia and cyprus basin eastern mediterranean is investigated by means of swath sounding reflection seismics and side scan data as well as by camera and video sledge observations both basins are located east of cyprus and are associated with the collision front between the african and anatolian plate the pliocene quaternary sediment succession is underlain by up to 1 km thick messinian evaporites both thick skinned plate tectonic and thin skinned salt tectonic control fluid dynamics and associated mud volcanism in the latakia and cyprus basin as well as at the troodos latacia culmination which separates both basins an end member model is proposed which explains the presence of elongated topographic highs and trenches along the troodos larnaca culmination and south of it by gravity gliding of the messinian evaporites and associated fluid migration thin skinned extension in the troodos larnaca culmination and boudinage respectively facilitate fluid flow through and out of the evaporites the fluid or mud flow dissolutes the salt layer and creates elongated trenches mud intrudes into the pliocene quaternary sediments above the trenches consequently the overburden is thickened and forms morphological ridges south of the culmination the evaporites and overburden are folded due to thin skinned shortening of the evaporites in one instance fluid extrusion out of the evaporites is inferred from seismic data interpretation the outflow caused a volume reduction and collapse of the evaporites mud volcanoes and fold anticlines align above deep rooted transpressional fault systems which are associated with the african anatolian collision zone the faults may act as conduits for rising fluids in the western part of the survey area where the cyprus arc strikes almost west east and the collision occurred more frontal and stress was highest mud volcanoes emerged further to the east where the cyprus arc runs sw ne and sinistral strike slip has been proposed fold anticlines evolved particular mud volcanoes and folds emerged prior to the deposition of the messinian evaporites the undisturbed upper pleistocene sequences as well as the absence of significant mud outflow on the seafloor strongly suggest that the main fluid dynamic ceased

continuous gps array and present day crustal deformation of japan a gps array with about 1 000 permanent stations is under operation in japan the gps array revealed coseismic deformations associated with large earthquakes and ongoing secular deformation in the japanese islands based on daily coordinate data of the gps stations strain rate distribution is estimated most regions with a large strain rate are related to plate boundaries and active volcanoes in addition the niigata kobe tectonic zone nktz is recognized as a region of large strain rate along the japan sea coast and in the northern chubu and kinki districts this newly found tectonic zone may be related to a hypothetical boundary between the eurasian or amurian and the okhotsk or north america plates precise observation of crustal deformation provides important boundary conditions on numerical modeling of earthquakes and other crustal activities appropriate computation methods of continuous deformation field are directly applicable to data assimilation for such numerical simulations

late tertiary subsidence history of the southern levant margin eastern mediterranean sea and its implications to the understanding of the messinian event the late tertiary subsidence history of the southern levant continental margin situated in the southeastern mediterranean sea was quantitatively analyzed paleodepth reconstruction across the margin off ashdod suggests the existence of a deep basin in pre messinian time which resembles the present one this implies that the deposition of the evaporites in the study area during the messinian desiccation of the mediterranean sea occurred in a deep basin the path of the tectonic subsidence of the basement since early tertiary is generally smooth as expected from the nature of the thermal subsidence the unconformity beneath the messinian indicates erosion of 50 200 m at the coastal plain in the pliocene the tectonic subsidence in the coastal plain and shelf area diverts from the expected thermal path and increases from 250 m to 450 m respectively in the quaternary the rate of tectonic subsidence nearly resumed the predicted thermal subsidence sedimentation and subsidence rates decrease but are still higher than those of the pre messinian we suggest that the evolution of the southern levant margin is most probably influenced by three main causes 1 the messinian event in late miocene 2 the deposition of large volumes of nile derived sediments since the pliocene and 3 the flexural response of the lithosphere to the load from the nile delta and or from the uplift of the judea mountains the western shoulder of the dead sea transform we interpret the latter to be the cause of the anomalous subsidence of the southern levant margin during the pliocene

3d seismic characterisation of an array of blind normal faults in the levant basin eastern mediterranean the geometry throw distribution and kinematics of an array of blind normal faults were investigated using a high resolution 3d seismic dataset located in the levant basin offshore israel to establish criteria allowing true blind faults to be distinguished from minor synsedimentary faults a detailed analysis of throw distribution on the fault planes shows that the displacement exhibits a crudely concentric pattern about a maximum region located centrally on a fault plane as expected for ideal blind faults however vertical displacement profiles do not exhibit classical linear or triangular profiles but are mostly flat topped or hybrid in type comparison of unrestricted blind faults to those that interacted with a mechanical boundary or another structure suggests that such interactions significantly modify the throw spatial distribution on a fault plane to distinguish small synsedimentary faults from blind faults we use a combination of three criteria to assess whether a fault grew by blind propagation 1 plunging upper tip region and complementary pattern in the throw contours 2 presence of upper tip propagation fold and 3 absence of stratigraphic evidence that the fault interacted with the free surface

the waiouru new zealand earthquake swarm persistent mid crustal activity near an active volcano 1 a persistent swarm of earthquakes occurs 25 km southeast of the summit of mt ruapehu an active volcano in the central north island of new zealand 319 swarm events recorded during a six month seismograph deployment in 2001 have been relocated using the double difference technique the relocated events define a vertical sheet in the mid crust with most activity 11 21 km deep both focal mechanisms and a stress inversion indicate strike slip motion for the swarm events in contrast to the normal faulting seen on a parallel active fault mapped at the surface various lines of evidence suggest the swarm is of tectonic origin and due to fluid movement it currently reflects the regional stress field rather than local stresses related to volcanic activity at mt ruapehu nevertheless changes in the activity of the swarm appear to correlate with eruptions and the swarm appears to have potential as a stress meter for monitoring nearby volcanic activity

completeness of the known graptoloid palaeontological record using a high resolution chronology of graptoloid first and last appearances we apply mathematical models that allow the simultaneous inference of the probability distribution of species durations and the effective sampling rate relating those durations to the observed stratigraphic ranges this approach allows the completeness of the documented palaeontological record of graptoloids to be assessed we estimate that c 75 of species in the geographical regions that contribute to the stratigraphic data have been sampled and that of those species known from more than a single stratigraphic horizon c 85 of their original durations on average are represented by their global composite stratigraphic ranges as expected in light of their biostratigraphic importance graptoloids have one of the most completely documented records among groups of fossil organisms we expect that application of the methods used herein will show comparably complete records for other biostratigraphically relevant groups supplementary material the r code and data are available at https doi org 10 6084 m9 figshare c 4547174

mediterranean messinian salinity crisis constraints from a coeval marginal basin sorbas southeastern spain abstract the extent timing and effects of late miocene desiccation and evaporite deposition in the mediterranean sea remain controversial marginal basins containing messinian 5 3 7 1 ma sequences now exposed onland supplement information from the deep mediterranean but have evaporites of a variety of ages some of these messinian evaporites pre date and others post date deep desiccation none appears to be exactly coeval with those of the deep mediterranean in the betic cordillera of southern spain basins e g granada basin far from the present day mediterranean lost connection with the mediterranean due to uplift 1 ma before the salinity crisis and have marine evaporites of early not late messinian age in contrast basins such as the sorbas basin in southeastern spain adjacent to the present day mediterranean record events directly reflecting the course of the salinity crisis the sorbas basin retained marine connection with the western mediterranean up until evaporative drawdown in the mid messinian and was rapidly reflooded immediately afterwards the sorbas messinian sequence is up to 320 m thick it is complete and normal marine except for an incised basinwide erosion surface overlain by a 130 m thick gypsum deposit we propose that this surface marks the interval of deep desiccation of the adjacent mediterranean basin erosion occurred shortly after 5 9 ma and the irregular unconformity has relief of at least 240 m confirming mediterranean drawdown significantly below the atlantic level sorbas gypsum deposits overlie the unconformity and are intercalated with marls estimated at 5 5 ma containing normal marine messinian biotas these gypsum deposits therefore post date deep desiccation and formed in a silled basin immediately following marine reflooding they mark the end of the salinity crisis and are overlain by 70 m of normal marine sediments containing unreworked foraminifers of latest messinian age this succession demonstrates that the salinity crisis occurred faster and was completed sooner than previously believed it took place within 0 4 ma time scale of berggren et al 1995b is 0 2 ma on the time scale of baksi 1993 and was completed before the end of the messinian this corrects previous views that the salinity crisis continued until the early pliocene there is no evidence in the sorbas basin for brackish lago mare conditions and the normal marine biotas that directly precede and follow drawdown rebut earlier suggestions of prolonged salinity effects

large heterogeneous structure beneath the atotsugawa fault central japan revealed by seismic refraction and reflection experiments abstract a high strain rate zone termed the niigata kobe tectonic zone is located in central japan and contains an active right lateral fault called the atotsugawa fault we present the results of an explosive source seismic experiment that focused on identifying the formation mechanisms of the fault the experiment used seven explosive sources and 1108 seismic stations and was undertaken during october 2007 in the area of the atotsugawa fault the seismic stations were set up on a survey line with a length of 170 km oriented orthogonal to the strike of the fault the linear array was used to identify the seismic structure of the fault zone and the deeper parts of the crust in the study area yielding fine details of the seismic structure of the crust along the profile line including lateral variations in p wave velocity and the configuration of layers in the crust a relatively low p wave velocity reflective zone was detected beneath the fault at depths of 15 25 km this zone also has extremely low s wave velocities directly underlies three active faults and contains three low resistivity zones that underlie these faults these reflective and low resistivity zones are thought to represent fluid within the crust and the data obtained during this study are consistent with a weak zone model for the formation of the active faults in the study area this suggests that the reflective layer represents a weak zone in the lower crust that is responsible for the concentration of deformation within the upper crust the presence of abundant fluids beneath the atotsugawa fault could also reduce the strength of the lower crust again focusing deformation related to the regional stress regime in areas that overlie these fluid containing zones the results suggest that the reflective layer was an important factor in the formation of the atotsugawa fault

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

halite clay interplay in the israeli messinian abstract the mavqi im formation in israel is the equivalent of the evaporite part of the messinian stage upper miocene it is found in the subsurface in the offshore with eastward extensions into ancient buried channels in the coastal plain and in the jordan rift valley and in a few outcrops southwest of lake tiberias most of the anhydrite horizons can be used as correlation markers lateral facies changes between halite anhydrite and shales can be traced this is interpreted as contemporaneous sedimentation in giant marine salt ponds halite and anhydrite and in drowned desert valleys and or salt marsh coasts shales with sabkha like anhydrites another type of shale is that directly underflooring halite horizons it is regarded as deep water halite facies in contrast with shallow water facies where halite overlies gypsum and or anhydrite a twofold bull s eye model is proposed which assumes that either a sedimentation of gypsum and halite was separated in space i e gypsum was deposited in the part of the basin proximal to oceanic inlets or on shallow shelves whereas halite was deposited in the central deep part of the basin or on its distal edge or b sedimentation of gypsum and halite was not contemporaneous or separated in time i e in the deep parts of the basin gypsum precipitates were disintegrated by anaerobic bacteria which removed the sulfate the lower limit of gypsum deposition is considered to be 200 m which is the lower limit of the photic and wave zones in the israeli messinian there is no difference between the clay minerals of marine and fluvial shales differentiation of marine shales from fluvial and mud flat shales is based on their geometry i e thin persistent horizons spreading across the whole area versus thick shale lenses wedging out in 500 1000 m distances another consideration is the palynologic and microfauna remains in the first case the cyst pollen ratio may be as high as 100 whereas in the second pollen is dominant