structural analogy between the piano key faults of deep water lebanon and the extensional faults of the canyonlands grabens utah united states the levant basin is a deep water basin in the eastern mediterranean region a large part of the basin contains a characteristic set of closely spaced normal faults informally called the piano key faults these normal faults trending nw se have a fairly high frequency map view spacing of approximately 3 4 km on average and tens to hundreds of meters of interpreted throw a large part of the pre messinian sedimentary strata is faulted including the entire miocene to oligocene sequence at depth all the faults consistently die out at the same intra eocene detachment level this stratigraphic level is interpreted to have a regionally developed shale sequence acting as the basal detachment surface for the piano key faults the amount of throw on the individual faults appears to decrease toward the basin margin and the faults do not extend into the adjacent basins of the broader eastern mediterranean area

local seismic array observations at north evoikos central greece delineate crustal deformation between the north aegean trough and corinthiakos rift abstract in order to better constrain and define the microseismic activity at the north evoikos gulf and its surrounding area we deployed an onshore offshore seismic array consisting of 31 three component seismic digital stations the array was active from 30 june to 24 october 2003 and covered an area of 2500 km 2 we located more than 2000 seismic events ranging from 0 7 to 4 5 m l by using six stations as a minimum in order to define the foci parameters recorded seismicity delineated three major zones of deformation from south to north the eretria parnis eastern corinthiakos zone the psachna viotia zone and the northern sporades north evia bralos zone alignments of the recorded seismicity follow the tectonic trends and their orientation in the above zones the whole area accommodates the stress field between the north aegean trough and the corinthiakos gulf rate of deformation intensifies from north to south as revealed also by historical and instrumental seismicity the successive change of orientation between the two stress fields fragments the crust in relatively small units and the fault systems developed do not permit the generation of major earthquakes in the north evoikos area and its immediate vicinity this is also supported by the instrumental seismicity of the last century larger events reported in historical times are probably overestimated most seismic activity is crustal subcrustal events were recorded mainly below the lichades area and are interpreted as the consequence of the subduction of the ionian oceanic lithosphere below the hellenides the lichades volcano is the most northern end of the hellenic volcanic arc at present the highest seismic activity is associated with the psachna region of north evia that has been continuously active since 2001 considering however the development of the seismic activity during the last decade there has been a sequence of large events i e parnis in 1999 skyros in 2001 and psachna in 2001 2003 this demonstrates the fact that the tectonic deformation in all this area is intense and important for the accommodation of the stress field of the north aegean trough to that of the corinthiakos rift

transport potential vorticity and current temperature structure across northwest providence and santaren channels and the florida current off cay sal bank currents and temperatures were measured using pegasus current profilers across northwest providence and santaren channels and across the florida current off cay sal bank during four cruises from november 1990 to september 1991 on average northwest providence 1 2 sv and santaren 1 8 sv contribute about 3 sv to the total florida current transport farther north e g 27 n partitioning of transport into temperature layers shows that about one half of this transport is of 18 c water 17 c 19 5 c this can account for all of the excess 18 c water observed in previous experiments this excess is thought to be injected into the 18 c layer in its region of formation in the northwestern north atlantic ocean due to its large thickness potential vorticities in this layer in its area of formation are very low in our data lowest potential vorticities in this layer are found on the northern end of northwest providence channel and are comparable to those observed on the eastern side of the florida current at 27 n on average a low potential vorticity 18 c layer was not found in the florida current off cay sal bank

the potential of arctica islandica growth records to reconstruct coastal climate in north west scotland uk this paper describes potential methods for reconstructing past marine environmental and climatic variability in scottish coastal waters through the investigation of annual growth increments measured from shells of the long lived marine bivalve arctica islandica l this is accomplished by using a combination of sclerochronological and dendrochronological techniques which were employed to determine the age of specimens and to create growth chronologies using negative exponential detrending methods a preliminary a islandica master chronology for the lynn of lorn scotland has been produced this chronology indicates highly suppressed growth between the mid 1940s and late 1980s the growth response of this species to the sea surface temperatures in scottish coastal waters appears to be complex most notably during recent decades when land use changes and marine aquaculture may influence shell growth at this site

magmatic subsidence of the east pacific rise epr at 18 14 s revealed through fault restoration of ridge crest bathymetry 1 the fault restoration technique of de chabalier and avouac 1994 is applied to an ultra high resolution bathymetry data set from the east pacific rise epr at 18 14 s fault offsets are calculated and subtracted from the original seafloor bathymetry to examine the morphology of the unfaulted seafloor surface within an area encompassing the ridge axis 400 1600 m in dimension the restored topography reveals a gently sloping seafloor 200 m wide which slopes 5 inward toward the spreading axis we attribute this inward sloping seafloor to subsidence within the axial trough due to subsurface magmatic deflation the vertical deformation field extracted from the bathymetry is used to characterize the ridge axis fault population present in the area median fault throws 9 m for inward facing and 8 m for outward facing faults are comparable to values measured for nearby mature abyssal hill fault populations suggesting a genetic link however median fault spacings 70 and 46 m are an order of magnitude smaller and estimated total extensional strain is 3 4 greater than values measured for ridge flank faults these differences indicate the axial fault population at 18 14 s cannot be rafted onto the ridge flanks to form abyssal hill faults without significant modification presumably via volcanic burial we attribute the dense faulting observed in this area to slip on axial fissures during subsidence of the crestal region the surface subsidence of a volcanic edifice can be modeled in terms of volume change in the magma source reservoir and volume of magma withdrawn from the reservoir using the relationship derived for a sill like magma body we estimate that the axial depression at 18 14 s could represent magma withdrawal associated with a small number 4 22 of the frequent dike injection and eruption events required to build the upper crust during the evolution of the trough the subsidence volumes represented by the axial topography at 18 14 s are a small percentage of the underlying upper crustal sections 3 4 suggesting that only a minor mismatch between magma recharge and withdrawal from the axial melt lens during ongoing plate separation could account for this pronounced axial depression

seismic energy mapping applied to sweden abstract the release of seismic wave energy provides a dynamic seismicity parameter of general applicability the moving block method is used for the seismic energy mapping of sweden on this basis some general problems connected with such mapping are discussed maps of this type may be useful for estimating other related quantities e g the maximum magnitude to be expected at any point

the little ice age and medieval warm period in the sargasso sea sea surface temperature sst salinity and flux of terrigenous material oscillated on millennial time scales in the pleistocene north atlantic but there are few records of holocene variability because of high rates of sediment accumulation holocene oscillations are well documented in the northern sargasso sea results from a radiocarbondated box core show that sst was approximately 1 degree c cooler than today approximately 400 years ago the little ice age and 1700 years ago and approximately 1 degree c warmer than today 1000 years ago the medieval warm period thus at least some of the warming since the little ice age appears to be part of a natural oscillation 39 refs 4 figs 1 tab

late holocene variability of upper north atlantic deep water temperature and salinity 1 magnesium calcium ratios in benthic foraminifera cibicidoides pachyderma from a sediment core on the laurentian slope 1854 m exhibit strong millennial scale fluctuations during the past 4000 years we convert these data to seawater paleotemperatures using a new monospecific linear equation results suggest that the temperature of upper north atlantic deep water dominated by labrador seawater today has varied by at least 2 c during the late holocene millennial scale coolings coincide with previously identified periods of increased drift ice and regional glacier advances including the little ice age paired oxygen isotope measurements indicate that salinity and perhaps density were reduced during the cold periods we discuss possible mechanisms for transmitting this cold fresh signal from surface waters to intermediate depths our reconstructed late holocene ranges in upper north atlantic deep water properties greatly exceed those of the instrumental record and imply that large changes may be yet to come

sliding and regional slope stability in active margins north aegean trough mediterranean continuous seismic air gun sub bottom profiling in the north aegean has revealed a large submarine slide the failure zone extends from a depth of about 300 m down to 850 m and covers an area of 85 km2 the mean thickness of the slide reaches about 55 m and an estimated total volume of 3 8 km3 of late pleistocene sediments has slid a distance of 6 7 km chronostratigraphic analysis of the acoustic reflectors imply that the major and secondary glide planes are the transitional zones between a lower sequence of strongly stratified reflectors stiff relatively coarser sediment layers and the overlying acoustically transparent and or poorly stratified sequence weaker muddy layers with higher water content and lower shear strength these weak transparent layers have been deposited during interglacial high sea level stands isotopic stages 7 5 3 the major glide plane is assumed to have been developed within a muddy layer that was deposited about 170 245 ka bp stratigraphic sedimentological data and ams dates indicate an early holocene age of the major failure event not earlier than about 5 5 ka bp and not later than 7 8 ka bp the regional seismic hazard and slope stability analysis shows that the north aegean marginal upper middle slopes are highly unstable the calculated values of horizontal ground acceleration able to initiate failures kc range from 80 to 300 gal downslope this is lower than what is expected within 50 yr especially in the upper middle slopes

a point sourced calciclastic submarine fan complex eocene anotz formation western pyrenees facies architecture evolution and controlling factors a complete transect of a fossil carbonate ramp slope has been reconstructed using outcrop data from the lower middle eocene anotz formation in the western pyrenees the anotz formation contains four calciclastic mostly bioclastic members encased within hemipelagic marl limestone alternations each calciclastic member representing a submarine fan system individual fans are composed of a gullied upper slope a leveed feeder channel a channelized lobe area an unconfined lobe zone and a peripheral lobe fringe that grades downcurrent into basinal deposits quantitative data on the dimensions and degree of lateral continuity and vertical connectivity of the anotz calciclastic fan elements are presented these data provide information for a better understanding of the intrinsic nature of calciclastic submarine fans and to model their reservoir potential the long term evolution of the anotz carbonate slope was generally progradational as evidenced by the four discrete episodes of calciclastic fan development the location of the fans was controlled by the synsedimentary tectonic activity of the pamplona fault which created a slope valley along which the reworked shallow water calciclastic sediments were funnelled in addition episodic basinward tilting of the shallow water carbonate ramp linked to the development of the south pyrenean foreland basin switched on and off the process of calciclastic resedimentation and determined the growth or abandonment of the fan systems

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

coralline algal growth increment widths archive north atlantic climate variability over the past decade coralline algae have increasingly been used as archives of paleoclimate information encrusting coralline algae which deposit annual growth increments in a high mg calcite skeleton are amongst the longest lived shallow marine organisms in fact a live collected plant has recently been shown to have lived for at least 850 years based on radiometric dating while a number of investigations have successfully used geochemical information of coralline algal skeletons to reconstruct sea surface temperatures less attention has been paid to employ growth increment widths as a temperature proxy here we explore the relationship between growth and environmental parameters in clathromorphum compactum collected in the subarctic northwestern atlantic results indicate that growth increment widths of individual plants are poorly correlated with instrumental sea surface temperatures sst however an averaged record of multiple growth increment width time series from a regional network of c compactum specimens up to 800 km apart reveals strong correlations with annual instrumental sst since 1950 hence similar to methods applied in dendrochronology averaging of multiple sclerochronological records of coralline algae provides accurate climate information a 115 year growth increment width master chronology created from modern collected and museum specimens is highly correlated to multidecadal variability seen in north atlantic sea surface temperatures positive changes in algal growth anomalies record the well documented regime shift and warming in the northwestern atlantic during the 1990s large positive changes in algal growth anomalies were also present in the 1920s and 1930s indicating that the impact of a concurrent large scale regime shift throughout the north atlantic was more strongly felt in the subarctic northwestern atlantic than previously thought and may have even exceeded the 1990s event with respect to the magnitude of the warming

the long lived mollusc arctica islandica a new paleoceanographic tool for the reconstruction of bottom temperatures for the continental shelves of the northern north atlantic ocean the carbonate shell of the bivalve arctica islandica has been recognized for more than a decade as a potentially important marine geochemical biorecorder owing to this species great longevity 200 years and wide geographic distribution throughout the northern north atlantic ocean a region vital to global climate and ocean circulation however until now this potential has not been realized owing to the difficulty of precisely sampling the shell of this slow growing species using newly available automated microsampling techniques combined with micromass stable isotope mass spectrometry a stable oxygen isotope record 1956 1957 and 1961 1970 has been obtained from a live captured 38 year old a islandica specimen collected near the former position of the nantucket shoals lightship 41 n 69 w the shell s 18o signal is compared with an expected signal derived from ambient bottom temperature and salinity data recorded at the lightship for the same period the results show that a islandica s 18o record 1 is in phase with its growth banding confirming the annual periodicity of this species growth bands 2 is in oxygen isotopic equilibrium with the ambient seawater 3 shows a consistent shell growth shutdown temperature of 6 c which translates into an 8 month may december shell growth period at this location and 4 records the ambient bottom temperature with a precision of 1 2 c these results add important information on the life history of this commercially important shellfish species and demonstrate that a islandica shells can be used to reconstruct inter and intra annual records of the continental shelf bottom temperature

seismic hazard in greece i magnitude recurrence two different methods are applied to the earthquake catalogue for greece makropoulos and burton 1981 mb catalogue to evaluate greek seismic hazard in terms of magnitude earthquake strain energy release and gumbel s third asymptotic distribution of extreme values it is found that there is a close relationship between results from the two methods in places where the cumulative strain energy release graphs include at least one well defined cycle of periodicity of strain release then the parameters of the third type asymptote are well defined with small uncertainties in almost all cases the magnitude distribution shows a remarkably good third type asymptotic behaviour the results are presented in the form of graphs and contour maps of annual and 80 year modes and magnitudes with 70 probability of not being exceeded in the next 50 and 100 years for six of the most heavily industrial and highly populated centres of greece magnitude hazard parameters are also derived and examined in more detail thereby illustrating the direct applicability of the methods in terms of zoning the close agreement between observed and predicted extreme magnitudes shows that the sample period considered 1900 1978 is long enough to obtain statistically stable estimates for athens the upper bound magnitude is found to be 6 7 0 3 within 100 km and 6 8 0 4 100 km from the two methods respectively whereas for corinth an earthquake of magnitude 6 5 has a mean return period of 43 years greece as a whole has an upper bound magnitude 8 7 0 6 and earthquakes of a size similar to the 1903 kithira event m 8 0 have a mean return period of about 200 years the significantly different maps contouring magnitudes of the annual and 80 year modes result from the fact that each place has its own distribution curvature for magnitude occurrence and thus they are not a linear extrapolation of each other however as longer return periods are considered these differences become small because the expected magnitudes approach the regional upper bound a feature common to all these maps is the existence of three well defined aseismic blocks 1 a the attikocycladic block 2 b the ptolemais basin and 3 c the block formed by the northeastern part of greece well defined areas of high seismic hazard which correlate with the most tectonically active areas are 1 a along the hellenic arc the greek albania border leukas cephalonia islands and the southeastern end of the arc 2 b the western end of the north anatolian fault and 3 c the chalkidiki peninsula and the northern sporadhes islands

slope failures and stability analysis of shallow water prodeltas in the active margins of western greece northeastern mediterranean sea sediment instabilities are common on the prodeltas of the seismically active continental margins of western greece sediment failures on the low angle 0 5 2 prodelta slopes manifest themselves as successions of peripheral rotational block slumps restricted to the foresets of the late highstand systems tract hst the individual slump blocks are about 80 150 m long and are bounded by growth faults acting as curved slip planes that extend to a mean depth of 10 15 m below seafloor shear planes develop in the lower part of muddy and or gas charged hst foresets deeper basal transparent muddy layers of the early hst bottomset together with the late pleistocene transgressive systems tract sequences tst are mostly unaffected on the steeper 2 6 fan delta slopes of the western gulf of corinth debris flows and avalanches with a significant retrogressive component dominate slope destabilisation sediment cores taken from landslide scarps and slide planes penetrated gas bubble releasing sediments thereby indicating that failure planes are in the late hst foresets upper part of the early hst bottomsets gas charged zone the foresets of the hst prodelta deposits display high water content 30 80 low bulk density 1 4 1 9 g cm 3 and relatively low values of undrained shear strength 3 20 kpa the water content of the hst distal muddy bottomsets is relatively higher 50 110 and bulk density relatively lower 1 3 1 7 g cm 3 with low values of shear strength 2 10 kpa the shear strength of the gas releasing sediment layer displays lower values 2 9 kpa relative to the overlying post failure muddy sediments of the late 100 300 years slope stability was calculated using the normalised soil parameter nsp method under undrained conditions for normally consolidated prodelta sediments this analysis indicates that instabilities could be induced by critical earthquake ground accelerations of 26 6 29 6 g for the hst foresets and 12 4 14 1 g for the basal transparent layer belonging to the early hst bottomsets consequently the early hst bottomsets has to be considered a potentially unstable layer since the regional peak ground accelerations pgas for the next 50 years are expected to range from 19 to 30 g moreover our results show that new glide planes in the prodeltaic sediment bodies of the seismically active continental margins of western greece will likely develop from the gas charged sediments of the lower part of the hst foresets to the upper part of early hst bottomsets

spatial mapping of earthquake hazard parameters in the hindukush pamir himalaya and adjacent regions implication for future seismic hazard abstract the study deals spatial mapping of earthquake hazard parameters like annual and 100 years mode along with their 90 probability of not being exceeded nbe in the hindukush pamir himalaya and adjoining regions for this purpose we applied a straightforward and most robust method known as gumbel s third asymptotic distribution of extreme values giii a homogeneous and complete earthquake catalogue during the period 1900 2010 with magnitude mw 4 0 is utilized to estimate these earthquake hazard parameters an equal grid point mesh of 1 longitude x 1 latitude is chosen to produce detailed earthquake hazard maps this performance allows analysis of the localized seismicity parameters and representation of their regional variations as contour maps the estimated result of annual mode with 90 probability of nbe is expected to exceed the values of mw 6 0 in the sulaiman kirthar ranges of pakistan and northwestern part of the nepal and surroundings in the examined region the 100 years mode with 90 probability of nbe is expected to exceed the value of mw 8 0 in the hindukush pamir himalaya with caucasus mountain belt the sulaiman kirthar ranges of pakistan northwestern part of the nepal and surroundings the kangra himanchal pradesh and kashmir of india the estimated high values of earthquake hazard parameters are mostly correlated with the main tectonic regimes of the examined region the spatial variations of earthquake hazard parameters reveal that the examined region exhibits more complexity and has high crustal heterogeneity the spatial maps provide a brief atlas of the earthquake hazard in the region

can polygonal faults help locate deep water reservoirs polygonal faults are compaction related normal faults that develop in very fine grained sedimentary successions despite their ubiquity few studies have highlighted the application of polygonal fault mapping to identifying deep water sandstone reservoirs we use three dimensional seismic and borehole data from the maloy slope offshore norway to demonstrate that the distribution cross sectional geometry and throw characteristics of polygonal faults can be used to locate deep water sandstone reservoirs we identify two tiers of polygonal faults in the cretaceous to lower paleogene succession the lowermost tier is stratigraphically restricted to the lower barremian to lowermost turonian succession and likely formed during the early turonian the uppermost tier spans the entire cretaceous succession and likely formed during the maastrichtian an abrupt decrease in the thickness of the upper tier occurs where a 92 m 302 ft thick sandstone rich slope fan is developed in the upper turonian interval furthermore the lower tips of faults in the upper tier which are defined by anomalously high throw gradients cluster at the top of the sandstone resulting in decoupling of this tier from the underlying lower turonian tier we interpret that faults in the upper tier nucleated above the reservoir across the entire slope and that the slope fan sandstone acted as a mechanical barrier to downward fault propagation resulting in abrupt thinning of the tier at the sandstone pinchout we demonstrate polygonal faults are not simply an academic curiosity mapping of these enigmatic structures can have practical applications for the delineation of a variety of reservoir types in hydrocarbon bearing sedimentary basins worldwide

initiation and propagation of polygonal fault arrays by thermally triggered volume reduction reactions in siliceous sediment abstract polygonal fault arrays have been documented in sedimentary basins from around the world and several theories exist as to how they initiate and propagate three dimensional seismic data from polygonal fault arrays from offshore norway are used to develop a new process model for polygonal fault development we propose that in siliceous sediment polygonal fault arrays can be triggered thermally due to the conversion of opal a to opal ct at depths of 100 1000 m this conversion causes differential compaction and shear failure and therefore fault initiation the location of the earliest faults is dependent on where opal a to opal ct conversion and compaction occur first this is controlled by which strata have a favourable bed composition local fluid chemistry and temperature or because the strata reach the depth of the reaction front first due to the presence of pre existing structural relief folds or faults subsidence of biosiliceous sediment through the opal a to opal ct reaction front causes fault propagation because of continued localised differential compaction fault initiation and propagation due to silica conversion generate polygonal fault arrays at significantly deeper burial depths than previously thought possible

a multi proxy reconstruction of tropical cyclone variability during the past 800 years from robinson lake nova scotia canada abstract this study presents a multi proxy reconstruction of tropical cyclone tc activity for the past 800 years from robinson lake located on the north atlantic seaboard of nova scotia canada two sediment cores were extracted from robinson lake and were dated by 210pb and 14c methods and analyzed for organic matter content sediment grain size and a range of elements and elemental ratios determined by xrf core scanning a distinct sand layer in the most recent sediments is attributed to hurricane juan which struck the coast of nova scotia on september 29 2003 our study shows that peaks in grain size farther down core are generally correlated with abrupt increases in br and br ti xrf derived br measurements are an indicator of marine organic carbon moc and the increases in br likely reflect incursions of marine water and nutrients into the lake as a result of storm surges the results show that the period from 1475 to 1670 ce contains at least 3 4 storm beds and are interpreted as the most active tc period within the last 800 years for this region our results are consistent with recent research from salt pond massachusetts donnelly et al 2015 which provides evidence for heightened tc activity during the same period as our study at robinson lake our study represents one of the highest latitude paleotempestological studies from the north atlantic basin which will help the testing of hypotheses concerning long term changes in north atlantic tc activity under future climate change scenarios

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

a catalogue of seismicity in greece and adjacent areas summary a new earthquake catalogue for greece has been formed to cover the instrumental period 1901 78 in particular 605 earthquakes for the period 1917 63 inclusive are relocated using first arrival data from the international seismological summary these relocations incorporate macro seismically and other well controlled master events into an ensuing joint epicentre determination technique the largest annual average shift is 165 km for 78 earthquakes during the decade after 1917 decreasing to 17 km for the later years 1957 63 magnitudes are redetermined mainly using readings from the swedish network and uppsala since as early as 1908 catalogue completeness exists for magnitudes around 5 5 for at least the last 60 years but magnitudes of about 4 7 are completely reported only during the most recent 15 years the new epicentral positions lead to a better delineation of the seismic zones than has previously been achieved the majority of shallow earthquakes are contained in a belt parallel to the hellenic arc which extends north into albania in the south east the epicentral locations give a more diffuse extension of this zone into the west coast of turkey depths of intermediate earthquakes along the hellenic arc tend to relocate to shallower depths in the south west part of crete no earthquake focus deeper than 100 km is found although in the south eastern section of the arc a tendency to increased depths is observed a second zone starts at leukas island in the west and extends through central greece to near volos on the east coast where it divides into two branches which are less well defined but which eventually join the seismicity of western turkey a third zone follows the saronikos and corinth gulfs

seismic hazard in greece ii ground acceleration abstract in a previous paper makropoulos and burton 1985 the seismic hazard in greece was examined in terms of magnitude recurrence using gumbel s third asymptotic distribution of extreme values and concepts of the physical process of strain energy release the present study extends the seismic hazard methods beyond magnitude to the estimation of expectations of levels of peak ground acceleration exceedance thus allowing for a direct comparison between these two methodologies as well as establishing information relevant to design and planning criteria the limited number of strong motion records do not permit regional study of attenuation of ground vibration in greece an average formula is derived from eight well known formulae which resulted from worldwide studies this is a 2164 e0 70m r 20 1 80 cm s 2 where a is peak ground acceleration m is earthquake magnitude and r is hypocentral distance in kilometres this formula agrees with the observed values of peak ground acceleration values recorded in greece acceleration seismic hazard is calculated at each of six chosen cities values of maximum acceleration with probability 70 of not been exceeded in the next 25 50 100 and 200 years are obtained along with corresponding values of velocity and displacement the same detailed acceleration evaluation is then applied to the whole area of greece by dividing it into cells of 0 5 lat 0 5 long and the results are illustrated through isoacceleration maps differences in magnitude and acceleration hazard maps reflect the fact that in acceleration hazard assessment the focal distance from a particular place in an important factor the cities of heraklion and rodhos have the lowest acceleration hazard although the expected earthquakes may have large magnitude intermediate depth earthquakes characterise these two cities acceleration estimates unlike magnitude hazard parameters refer to a particular place and not to an area around it hence even if two places have similar earthquake depth distributions the hazards may differ significantly because of the different spatial distribution of the foci this is observed in the case of athens and corinth these cities have almost the same magnitude hazard but the acceleration hazard is much lower for athens where the hazard is mainly due to more distant earthquakes the isoacceleration maps for greece as a whole also define areas of high seismic hazard these are the areas around cephalonia and leukas islands in the ionian sea and the eastern sporadhes lesbos islands and chalkidiki in the northern aegean sea at the 70 probability level the maximum acceleration is expected to be around 0 2g within the next 50 years the areas where the maximum acceleration at the 70 probability level is expected to reach a value of 0 3g in the next 200 years are around cephalonia and leukas islands and near the dardanelles

achievements and probable trends in seismic hazard assessment abstract the seismic hazard can be expressed in different ways from simple observed macroseismic fields to seismostatistical calculations for analyzing earthquake occurrences in time and space and assessing their dynamic effects in a certain site or region to sophisticated seismogeological approaches for evaluating the maximum expected earthquake effects on the earth s surface the advantages and shortcomings of each method means of delineating source regions testing the quality of input data processing such data to suit the chosen method of hazard assessment and estimates of the maximum expected earthquake magnitude and of the attenuation relationships as well as the extent of the errors in all these factors will be presented

coupled north atlantic slope water forcing on gulf of maine temperatures over the past millennium to investigate ocean variability during the last millennium in the western gulf of maine gom we collected a 142 year old living bivalve arctica islandica l in 2004 and three fossil a islandica shells calibrated 14cams 1030 78 ad 1320 45 ad 1357 40 ad for stable isotope and growth increment analysis a statistically significant relationship exists between modern gom temperature records shell isotope derived 30 m r 0 79 p 0 007 prince 5 50 m r 0 72 p 0 019 boothbay harbor sst r 0 76 p 0 011 and labrador current lc transport data from the eastern newfoundland slope during 1993 2003 in all cases as lc transport increased gom water temperatures decreased the following year decadal trends in the north atlantic oscillation nao and the atlantic multidecadal oscillation amo influence gom water temperatures in the most recent period with water temperatures decreasing during nao and amo negative modes most likely linked to lc transport and gulf stream interaction mean shell derived isotopic changes 18oc during the last 1 000 years were 0 47 and likely reflect a 1 2 c cooling from 1000 ad to present based on these results we suggest that observed cooling in the gom during the last millennium was due to increased transport and or cooling of the lc and decreased gulf stream influence on the gom

present day seismicity and seismotectonics of the cilician basin eastern mediterranean region of turkey the nature of the interaction between the anatolian arabian and af rican plates is an important problem of northeastern mediterranean tectonics the dead sea fault and east anatolian fault zone are the most prominent structural elements in this region the cilician basin which is located at the junction of these faults is known to have a very active seismic history however instrumental obser vations have been insufficient because of the lack of an adequate local seismic net work to monitor ongoing seismic activity and to analyze the seismotectonics of the cilician region 36 to 38 n 34 to 38 e a digital seismic network of 18 stations with velocity transducers has been operated by the earth and marine sciences re search institute emsri of the scientific and technical research council of turkey tubitak since 1993 no previous studies have been carried out in this region for crustal structure an optimum 1d velocity model was obtained by using the velest algorithm for reliable determination of earthquake hypocenter locations approxi mately 2500 earthquakes detected between 1993 and 2002 with local magnitude greater than 1 5 have been located by using this optimum velocity model the most notable feature of the epicentral distribution is the presence of dense clusters of activity along local fault trends the majority of hypocentral depths of the events range between 5 and 35 km single fault plane solutions of reliable events were calculated in order to analyze the seismotectonic characteristics of the region results show that the cilicia region constitutes a wide left lateral shearing zone that indicates a diffuse plate boundary between the african arabian and anatolian plates

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

shell sclerochronology and stable oxygen isotope ratios from the limpet patella depressa pennant 1777 implications for palaeoclimate reconstruction and archaeology in northern spain abstract stable oxygen isotope ratios of mollusc shells 18oshell offer the possibility to reconstruct coastal resource exploitation patterns and changes in the oceanographic conditions of direct relevance to past human populations this method relies on the fact that shell carbonate is deposited by molluscs in equilibrium with their surrounding environment and actualistic investigation of modern specimens is needed to ensure that selected species can be used as accurate palaeoclimate indicators the limpet patella depressa pennant 1777 is one of the most common mollusc species found in holocene archaeological assemblages along the atlantic coast of europe however this taxon has not to date been tested as a seawater palaeothermometer here we explore the ability of p depressa to be used as an environmental recorder in this littoral region specifically in northern iberia where we obtained live collected specimens throughout the year we undertook sclerochronological investigations combining observations of incremental shell growth patterns with 18oshell values carbonate samples were taken on i the ventral margins of shells collected alive year round in order to test for isotopic equilibrium and ii along the axis of maximum shell growth of four modern specimens to decipher the shell growth pattern of this species isotopic data showed that calcium carbonate is precipitated in predictable isotopic disequilibrium with the ambient seawater r2 0 95 p

water sources for georges bank abstract the origins of georges bank source waters can be quantified by the oxygen isotope salinity tracer regionally water is tagged by freshwater of different h 2 18 o h 2 16 o ratios and these waters can subsequently be identified after mixing downstream this conservative lagrangian tracer of source waters is useful for tracking passive plankton and larvae that may be important to sustain the georges bank ecosystem the origin of georges bank freshwater sources is primarily in the gulf of st lawrence consisting of labrador shelf water which enters via the strait of belle isle and st lawrence river water these two mix with the underlying slope water in the gulf of st lawrence and along the scotian shelf at the northeast channel the input to the gulf of maine there is a single freshwater endmember consisting of 5 6 st lawrence river water and 94 6 labrador shelf water by volume these proportions remained constant for the years 1995 1997 the water on central georges bank consists of a mixture of water entering the northeast channel with gulf of maine river outflow there is considerable interannual variation in the maine river water proportion ranging from 3 3 in 1982 to 0 23 by volume in 1996 during 1995 1998 there was no correlation between georges bank salinity which decreased monotonically and the proportion of maine river water on the bank the interannual fluctuations of salinity on georges bank are driven by variations in upstream scotian shelf sources and its mixing onto the bank and not by changes in local river outflow

a 250 year decadally resolved radiocarbon time history in the gulf of maine reveals a hydrographic regime shift at the end of the little ice age

tectono stratigraphic evolution of the northern levant basin offshore lebanon abstract seismic interpretation constrained by a detailed assessment of the levant paleogeography allowed subdividing the sedimentary infill of the northern levant basin offshore lebanon in eight major seismic packages fifteen seismic facies have been identified with distinctive characteristics the levant basin architecture is pre determined by a late paleozoic early mesozoic rift that led to the formation of a passive margin dominant aggrading carbonate platforms are observed along the levant margin and deepwater mixed settings i e carbonates and siliciclastics are suggested to prevail in the basin the collision of afro arabia with eurasia led to the development of a flexural basin in the northernmost offshore lebanon since the late cretaceous a southward migration of this flexural depocenter in the miocene is hindered by the change in the stress field along the latakia ridge and by the westward escape of the anatolian plate in late miocene and pliocene times interplay between major geodynamic events as well as sea level fluctuations in the mesozoic and cenozoic induced important marginal uplifts and emersion sediments sourced from the erosion of nubian siliciclastic material and from the exposed granitic red sea rift shoulders and arabian shield were driven into the levant basin the sediment sources diversity the mechanisms of sediment transport through varied pathways i e the levant margin canyons the latakia region and the nile delta deep sea cone are expected to strongly impact the reservoir characteristics and prospectivity of the northern levant basin

strontium magnesium and barium incorporation in aragonitic shells of juvenile arctica islandica insights from temperature controlled experiments abstract in order to constrain spatial and temporal temperatures and environmental conditions in the north atlantic ocean during the holocene high resolution seasonal to annual marine proxies with excellent chronological constraints are needed the long lived ocean quahog arctica islandica which has the potential to provide a precise annually dated record via crossdating techniques is a fairly well developed and tested marine proxy archive in particular oxygen isotopes derived from a islandica shell carbonate have provided a wealth of information on marine climate and ocean circulation dynamics however shell derived oxygen isotopes are influenced by both the isotopic source water signature covarying with salinity and seawater temperature if seawater isotopic signature is not known temperature reconstructions become challenging thus an independent technique to estimate past seawater temperatures is highly desired however based on previous studies on adult and juvenile clams the utility of elemental ratios in a islandica shell material as environmental proxies remains questionable to further evaluate the influence of seawater temperature on elemental and isotopic incorporation during biomineralization a islandica shells were grown at constant temperatures under two regimes during a 16 week period from march 27 to july 21 2011 at the darling marine center in walpole maine individual juvenile clams were stained with calcein and cultured at 10 30 0 30 c for six weeks after this the clams were again stained with calcein and cultured at 15 00 0 40 c for an additional 9 5 weeks average salinity values were 30 20 0 70 and 30 70 0 70 in the first and second phases of the experiment respectively continuous sampling within and across the temperature conditions from 10 30 c to 15 00 c coupled with the calcein markings provided the ability to place each sample into a precise temporal framework and to establish exact average growth rates for the shells sampled after accounting for changes in the isotopic composition of seawater oxygen isotopes from one sampled shell effectively recorded seawater temperatures during the study and also gave confidence to the temporal fit of the data elemental ratios sr ca mg ca ba ca from five aragonitic shells were determined via laser ablation inductively coupled plasma mass spectrometry sr ca and mg ca data showed little coherence with temperature during the culture experiment including the rapid 5 c increase in seawater temperature however ba ca ratios showed an inverse relationship with seawater temperatures although this relationship was noisy additionally salinity interactions were present during the 15 00 c treatment further highlighting complex incorporation of elements during biomineralization incorporation of sr mg and ba were strongly and variably impacted by growth rates combined the results from these culture experiments demonstrate that sr ca mg ca ba ca ratios in juvenile a islandica shell material are dominated by physiological processes and thus not reliable as environmental proxies

sedimentological processes in the southern margin of the cretan sea ne mediterranean abstract the cretan basin can be characterized as a back arc basin of the hellenic trench system that is related to the subduction zone of the african plate under the eurasia plate the study area includes the narrow and relatively steep gradient 1 5 continental shelf of the island of crete followed by the steep slope 2 4 and the rather flat deeper part of the cretan basin water depths 1700 m surficial sediments of the coastal zone are coarser and of terrigenous origin while in deeper waters finer sediments of biogenic origin are more abundant sand sized calcareous sediment accumulations identified in middle lower slope may be attributed to the aggregation of seabed biogenic material related to the near bed current activity high resolution profiles 3 5 khz taken from the inner shelf shows a typical sigmoid oblique progradational configuration implying prodelta sediment accumulation during the holocene in the upper middle slope sub bottom reflectors indicate continuous sedimentation of alternating fine and or coarse grained material small scale gravity induced synsedimentary faults appeared locally in contrast a series of gravity induced faults identified in the lower slope are associated with sediment instabilities due to seismotectonic activity sediment cores taken from the shelf break consists of calcareous muddy sand with small amounts of terrigenous silt and fine sand while the cores recovered from the middle slope has revealed a more homogeneous fine sediment texture of hemipelagic deposition the prevailing accumulation processes in the southern margin of the cretan basin are i prodelta deposition in the inner middle shelf ii settling from bottom nepheloid layers in the shelf and upper slope iii calcareous sediment formation due to settling from suspension and post accumulation aggregation middle lower slope iv long term episodic sediment gravity processes in the lower slope and v to a lesser extent redeposition from resuspension due to gravity processes and bottom currents

perceptible earthquakes in the broad aegean area abstract a probabilistic estimate of seismic hazard can be obtained from the spatial distribution of earthquake sources their frequency magnitude distribution and the rate of attenuation of strong ground motion with distance we calculate the earthquake perceptibility i e the annual probability that a particular level of ground shaking will be generated by earthquakes of particular magnitude by weighting frequency magnitude data with the predicted felt area for a given level of ground shaking at a particular magnitude this provides an earthquake selection criterion that can be used in the anti seismic design of non critical structures we calculate the perceptibility at a particular value of isoseismal intensity peak ground acceleration and velocity as a function of source magnitude and frequency for the broad aegean area using local attenuation laws we use frequency magnitude distributions that were previously obtained by combining short term catalogue data with tectonic moment rate data for 14 tectonic zones in greece with sufficient earthquake data and where contemporary strain rates are available from satellite data many of the zones show a characteristic earthquake distribution with the most perceptible earthquake equal to the maximum magnitude earthquake but a relatively flat perceptibility between magnitudes 6 and 7 the maximum perceptible magnitude is in the fastest deforming region in the middle of the aegean sea and tends to be systematically low on the west in comparison to the east of the aegean sea the tectonic data strongly constrain the long term recurrence rates and lead to low error estimates 0 2 in the most perceptible magnitudes

new research on the development of high resolution palaeoenvironmental proxies from geochemical properties of biogenic carbonates abstract geochemical signatures from biogenic carbonates are being increasingly employed as palaeoenvironmental proxies in turn many of these proxy archives including mollusc shells corals and otoliths have periodic growth structures which allow the reconstruction of chronologically constrained records of palaeoenvironmental variability at unparalleled high temporal resolution studying the growth and chemistry of these periodic growth structures is known as sclerochronology biogenic hard parts accumulate in geological or archaeological deposits and can be directly dated using radiometric and racemisation methods they therefore offer the opportunity for high resolution palaeoenvironmental reconstructions across many time intervals all over the globe such data are important for several reasons 1 understanding past climate and environmental change provides a means of contextualising current and future climate change and ecological disturbance 2 high resolution palaeoenvironmental records are essential for constraining testing and validating global and regional numerical climate models 3 palaeoenvironmental records from biogenic carbonates can provide an environmental framework from which to understand the behavioural changes and interactions of peoples with their environment however inter and intra species differences in growth rate physiology and environmental response can cause variations in the chemical profiles of biogenic carbonates before geochemical data is employed for palaeoenvironmental reconstructions it is thus necessary to examine modern specimens of the target species or related taxa to understand how geochemical variations are influenced by local environmental conditions kinetic and vital effects this allows the generation of quantitative and more reliable proxy records of environmental change this special issue brings together the latest research on palaeoenvironmental proxy development and validation in biogenic carbonates it includes studies on marine freshwater and estuarine organisms molluscs corals and echinoderms and on traditional as well as novel geochemical proxies the papers presented here include in situ field calibration studies laboratory growth experiments as well as methodological studies into the effects of sampling and pre treatment the geographical scope is broad encompassing both the northern and southern hemispheres including south africa south america australia asia the mediterranean sea and the north atlantic

cooling of northwest atlantic slope waters during the holocene 2 greenland ice cores depict a holocene climate that was warm and stable compared to the preceding 100 kyr yet most elements of the climate system were undergoing large secular changes during the last 11 kyr summer insolation in the northern hemisphere declined to last glacial maximum lgm levels atmospheric co2 increased 20 ppmv and the carbonate ion concentration of the deep sea decreased 5 10 mmol kg broecker et al 1999 signaling a large shift in the global carbon cycle the oxygen isotope composition of atmospheric o2 an indicator of global productivity and hydrology increased 0 5 retracing roughly 50 of the non ice volume deglacial decrease bender et al 1999 the monsoons of asia and

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

impact of cenozoic strike slip tectonics on the evolution of the northern levant basin offshore lebanon sedimentary basins adjacent to plate boundaries contain key tectonic and stratigraphic elements to understand how stress is transmitted through plates the levant basin is a place of choice to study such elements because it flanks the levant fracture system and the africa anatolia boundary this paper uses new high quality 3 d seismic reflection data to unravel the tectonic evolution of the margin of this basin during the cenozoic the period corresponding to the formation of the levant fracture system part of the africa arabia plate boundary four major groups of structures are identified in the interpreted cenozoic units nw se striking normal faults nne ssw striking thrust faults ene wsw striking dextral strike slip faults and nne trending anticlines we demonstrate that all structures apart of the nw se striking normal faults are inherited from mesozoic faults their reactivation and associated folding started during the late miocene prior to the messinian salinity crisis due to a nw se compressional stress field no clear evidence of shortening at present day offshore lebanon and no large nne ssw strike slip faults parallel to the restraining bend are found indicating that the levant fracture system is mainly contained onshore at present day the intermittent activity of the interpreted structures correlates with the two stages of levant fracture system movement during late miocene and pliocene this paper provides a good example of the impact of the evolution of plate boundaries on adjacent basins and indicates that any changes in the stress field as controlled by the plate boundary will affect immediately the preexisting structures in adjacent basins

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

new imaging of the salinity crisis dual messinian lowstand megasequences recorded in the deep basin of both the eastern and western mediterranean through several examples we show that following sea level fall and marginal erosion during the messinian salinity crisis msc clastic inputs into the eastern and western mediterranean sea are not distributed evenly in space and time but are mainly limited to the lower section of the messinian salinity crisis depositional megasequence significant similarities around the basin allow us to propose a mediterranean messinian salinity crisis depositional episode that can be divided into two seismic megasequences the messinian lower megasequence mlm and the messinian upper megasequence mum their distinctive seismic facies correspond to systems tracts deposited during three main stages that represent a complete sea level cycle 1 a falling stage systems tract including mass transport deposits and forced regressive clinoforms deposited in in the early part of the falling stage and related to the increasing rate of relative sea level fall this stage is characterized by a marked shift in the depocenter towards the deep basins 2 an early lowstand characterized by massive clastic inputs from major messinian rivers the rhone nile and antalya gulf rivers or smaller river systems offshore south lebanon these clastics were deposited in an oversaturated basin as evidenced by the interfingering chaotic and transparent seismic facies of the messinian lower megasequence mlm 3 a late lowstand starting with rapid deposition of massive halite with no detrital inputs into the deep basin the upper part of the evaporites clearly onlaps the messinian erosional surface at the margins and is evidence for a transition between a late lowstand stage and an early transgressive stage these deposits belong to the messinian upper megasequence mum we interpret the transition between the two megasequences as the peak of the salinity crisis the end of the relative sea level fall and the maximum dispersal of sands into the deep mediterranean basins

temperature and salinity variability on the scotian shelf and in the gulf of maine 1945 1990 examination of temperature and salinity data from the scotian shelf gulf of maine gulf of st lawrence and the adjacent continental slope has shown that the dominant low frequency event over the last 45 years was a cooling and subsurface freshening of the water masses from 1952 to 1967 followed by a rapid reversal of these trends the largest temperature and salinity changes 1952 1967 were 4 6 c and 0 7 respectively and occurred at about 100 m over the slope exchanges with shelf waters and vertical mixing gave rise to the surface manifestation of this variability the westward transport of the labrador current was found to have similar variability increasing from about 1 106 m3 s 1 in the early 1950s to about 4 106 m3 s 1 in the mid 1960s a simple model that accounts for this variation of transport and has a constant entrainment of north atlantic water indicates that changes of the westward flow of the labrador current could contribute significantly to the t s fluctuations

proteinaceous corals as proxy archives of paleo environmental change abstract high resolution marine data are critical to evaluating anthropogenic impacts on our environment considering the spatial and temporal limitations of direct instrumental measurements proxy data extracted from marine environmental archives are necessary to separate anthropogenic changes from those that would occur naturally the majority of late holocene high resolution environmental reconstructions are derived from marine carbonates including tropical scleractinian corals bivalves crustose coralline algae and sclerosponges however these archives are restricted to the top hundreds of meters of the water column and only preserve environmental variability that is captured by calcium carbonate skeletons at a very few select locations marine sediments archive annual environmental variability in organic and inorganic materials recently additional types of corals are proving to yield information complimentary to these traditional marine archives including cold water scleractinian corals and proteinaceous corals a taxonomically diverse group the proteinaceous corals are broadly defined as those having a branching gross morphology with skeleton comprised at least partly of protein rich organic material they encode characteristics of their food and ambient environment into the chemical and physical composition of their skeleton this environmental encoding combined with their banded skeleton and significant longevity means that proteinaceous corals hold information in their skeleton that helps fill the spatial and temporal gaps in our knowledge of past and present ocean conditions here i review the environmental reconstructions derived from geochemical measurements of the proteinaceous coral skeletons this information is grouped into the mesopelagic environmental variability captured in the skeleton of bamboo corals surface processes captured in the organic skeletons of corals across all ocean depths and environmental variability documented by skeletal radiometric isotopes we include animals from two separate subclasses within the class anthozoa including the parasitic zoanthids that secrete a sclero proteic skeleton since the proteinaceous corals are taxonomically diverse we consider the unique features that define this group of corals including their distribution morphology nutrition and longevity we find that uncertainty surrounding biological parameters limits the precision of reconstructions derived from the calcitic skeleton in contrast analytical effort and cost constrain the number of reconstructions from the organic skeleton through this discussion we provide insights into the uses challenges and directions for future research for this important environmental archive

constraining sediment transport to deep marine basins through submarine channels the levant margin in the late cenozoic abstract the recent world class gas discoveries in early miocene sand units offshore israel raises the question of their origin apparently the simplest explanation is to relate them to a fluvial system that arrived from arabia at that time this system predated the modern pliocene nile river supply and existed until captured by the dead sea valley interestingly however very little sedimentation occurred along the levant continental margin before the pliocene in spite of its stepped structure that provided much space for accommodation the only way that sediments could have bypassed the continental margin and arrive at the deep basin without being trapped in the middle is through submarine channels that crossed the continental margin here we explore this possibility using 3 d stratigraphic modeling techniques that quantify the sediment load and the water discharge required to fill the basin by pushing enough sediment through submarine channels we show that such a scenario requires a fluvial system in the order of the largest rivers that exist today on earth in terms of drainage area and water discharge alternatively it requires extreme hydraulic conditions in terms of diffusion coefficients and an elevated drainage basin that could not have existed in the study area we therefore challenge the traditional view of arabia as the main source for oligo miocene deposits in the levant basin and suggest that the basin was mainly fed by a proto nile system that transported clastic material to the north african margin and then farther east by ocean currents in a wider view we demonstrate how numerical modeling can constrain sediment transport through submarine channels as a function of basin geometry and hydraulic conditions and how paleogeographic knowledge can be combined with current data on world rivers to evaluate if modeling results are plausible

an estimate of probabilistic seismic hazard for five cities in greece by using the parametric historic procedure a probabilistic procedure was applied to assess seismic hazard for the sites of five greek cities athens heraklion patras thessaloniki and volos using peak ground acceleration as the hazard parameter the methodology allows the use of either historical or instrumental data or a combination of both it has been developed specifically for the estimation of seismic hazard at a given site and does not require any specification of seismic sources or and seismic zones a new relation for the attenuation of peak ground acceleration was employed for the shallow seismicity in greece the computations involved the area and site specific parts when assessing magnitude recurrence for the areas surrounding the five cities the maximum magnitude mmax was estimated using a recently derived equation the site specific results were expressed as probabilities that a given peak ground acceleration value will be exceeded at least once during a time interval of 1 50 and 100 years at the sites of the cities they were based on the maximum peak ground acceleration values computed by assuming the occurrence of the strongest possible earthquake of magnitude mmax at a very short distance from the site and using the mean value obtained with the help of the attenuation law this gave 0 24 g for athens 0 53 g for heraklion shallow and 0 39 g heraklion intermediate depth seismicity 0 30 g for patras 0 35 g for thessaloniki and 0 30 g for volos in addition the probabilities of exceedance of the estimated maximum peak ground acceleration values were calculated for the sites the standard deviation of the new greek attenuation law demonstrates the uncertainty and large variation of predicted peak ground acceleration values

forearc structures and tectonic regimes at the oblique subduction zone between the hikurangi plateau and the southern kermadec margin the convergent southern kermadec margin is examined to study the structural development and mechanical parameters of the inner trench slope in response to the oblique subduction of the oceanic hikurangi plateau swath bathymetric data have been combined with other geophysical data to reveal that the south kermadec inner trench wall is segmented into distinct upper middle and lower margins the lower margin is a nongrowing compressionally unstable accretionary wedge that is dissected by transcurrent faults the wedge has been thinned and narrowed as a result of tectonic erosion the middle margin is stable by comparison and separated from the lower margin by the 220 km long awanui fault this fault is a landward dipping strike slip reverse fault the middle upper margin including east cape ridge ecr forms a deforming backstop with a sharp along strike change in tectonic regime south of 36 40 s transpression characterizes the ecr shear zone north of 36 40 s the ecr is marked by uplift by extension and farther north by subsidence it is suggested that subsidence and subsequent tectonic erosion of the margin north of 35 50 s in the wake of hikurangi plateau subduction have broken the link between once continuous segments of the ecr tonga platform the unstable nature of the southern kermadec wedge under compression together with a comparison of its taper characteristics with those of modern convergent margins implies that the wedge deforms under a relatively high internal pore pressure but high effective basal friction regime strike slip deformation in the wedge is attributable to a relatively strong interplate coupling related to the buoyancy and ruggedness of the hikurangi plateau

the flip side of the north atlantic oscillation and modal shifts in slope water circulation patterns a large single year reversal in the phase of the north atlantic oscillation nao during 1996 led to a dramatic shift in the slope water circulation patterns of the northwest nw atlantic analyses of time series data collected from the region over the past half century show that both physical and biological responses are commonly elicited by such phase reversals in the nao here we use a model developed from time series data to predict responses of the nw atlantic slope water circulation patterns to phase reversals in the nao

climate records from a bivalved methuselah arctica islandica mollusca iceland we measured annual shell growth rates of a 374 year old radiometrically confirmed bivalve mollusk specimen of arctica islandica linnaeus this bivalve represents the oldest ever reported individual animal in addition we analyzed 1051 individual powder samples from ontogenetic years two to 40 80 of the entire shell height for isotope analyses oxygen and carbon isotopes exhibit clear intra annual cycles the highest measured carbon isotope values on average 2 73x occurred during summer i e during maximum primary productivity the d 18 oaragonite derived temperature time series cover the period of ad 1496 1533 temperatures calculated from oxygen isotopes ranged from 4 5 to 9 3 8c and exhibit a mean value of 6 2 8c the latter coincides well with the 1854 2003 mean value of 6 81 8c for sea surface temperature between february and september growing season of a islandica neither oxygen nor carbon isotopes exhibit age related unidirectional trends however d 13 caragonite and d 18 oaragonite values fluctuated at decadal periods of four six and eight to nine years nao type periods as well as 12 14 years which may represent teleconnections to cycles in the tropical atlantic annual shell growth is positively correlated to intra annual d 18 oaragonite minima i e warm summer temperatures r 2 0 34 and to intra annual d 13 caragonite minima higher food supply r 2 0 42 using a linear multiregression model 65 of the variation in annual shell growth can be explained by summer temperature and food supply the formation of extremely narrow annual increments coincides with major volcanic eruptions e g tambora 1815 a period of extremely variable growth occurred during the culmination of the little ice age in iceland between ca ad 1550 and 1620 shell growth during ad 1765 1780 however was characterized by very little year to year variability probably as the result of extremely mild climate near the end of the little ice age this study demonstrates that shells of a islandica provide

earthquake frequency and energy in greece abstract on the basis of a newly published revised earthquake catalogue for the greek area a study is made of its seismicity in terms of earthquake frequency and energy as functions of space time and magnitude in addition attempts are made to estimate the maximum possible magnitudes as functions of space the study is essentially a methodological experiment with tectonophysical and engineering results

a hemispheric mechanism for the atlantic multidecadal oscillation abstract the physical processes associated with the 70 yr period climate mode known as the atlantic multidecadal oscillation amo are examined based on analyses of observational data a deterministic mechanism relying on atmosphere ocean sea ice interactions is proposed for the amo variations in the thermohaline circulation are reflected as uniform sea surface temperature anomalies in the north atlantic these anomalies are associated with a hemispheric wavenumber 1 sea level pressure slp structure in the atmosphere that is amplified through atmosphere ocean interactions in the north pacific the slp pattern and its associated wind field affect the sea ice export through fram strait the freshwater balance in the northern north atlantic and consequently the strength of the large scale ocean circulation it generates sea surface temperature anomalies with opposite signs in the north atlantic and completes a negative feedback the authors find that the time scale of the cycle is associated with the

sea surface water temperatures over the period 1884 1983 reconstructed from oxygen isotope ratios of a bivalve mollusk shell arctica islandica southern north sea although climate system modeling cannot be imagined without long sea surface temperature sst records observational data is spatiotemporally incomplete and inhomogeneous prior to about 1950 moreover almost no high resolution sst proxies exist from temperate and boreal marine settings here we present a temporally equidistant high resolution sst proxy record of the southern north sea during the period 1884 1983 calculated from oxygen isotope ratios 18oaragonite of arctica islandica l a bivalve mollusk shell arctica islandica produces daily growth increments which enable precise intraannual dating the growing season of specimens from about 25 m water depth upper well mixed layer of the ocean started in february and ended in september observational coads etc and 18oaragonite derived sst data during february through september compare well to each other especially after 1950 apart from similar overall sst trends we found north atlantic oscillation type cycles of 7 9 years in our proxy sst record and in various different instrumentally determined sst chronologies no vital effects exist so that 18oaragonite ratios determined across the shell i e throughout lifetime of the studied specimen reflect ambient water temperatures that occurred during shell growth results of our study demonstrate that a islandica provides long independent and high resolution sst proxy chronologies from higher latitudes such records can complement and further validate observational sst data and help improving climate system models

sr ca profile of long lived tridacna gigas bivalves from south china sea a new high resolution sst proxy abstract high resolution 18o and sr ca ratio profiles of a modern live caught and a fossil dead collected giant bivalve shell tridacna gigas from northern south china sea were analyzed the high resolution 18o profiles as documented in most of previous studies showed pronounced seasonal cycles and recorded the combined influence of seawater 18o and sea surface temperature the sr ca ratio profiles derived from icp oes had well defined annual cycles and significant and negative correlation with sea surface temperature while the sr ca profiles derived from la icp ms did not reveal clear annual cycles this difference was likely caused by the organics contents in t gigas shells which had a chemical composition different than caco3 crystals and a heterogeneous distribution across the shell the sampling methods and the experimental errors two calibration equations between sr ca ratios determined by icp oes of modern t gigas shell and instrumental sst were calculated based on all monthly and extremum sst data and the equation from extremum data produced better sst predictions these results suggested that the high resolution icp oes derived sr ca ratios of t gigas in the south china sea had the potential of providing a good proxy of historical sst

seismic energy mapping applied to turkey abstract the moving block method for seismicity mapping in terms of the released seismic wave energy is applied to turkey it is demonstrated that this method is applicable to regions of a high seismicity in addition to those of a low seismicity demonstrated earlier the generalization smoothing in space provided by the map is extended to a generalization in time approximate time independence by connecting the mapped total magnitude with the maximum magnitude to be expected in each block the mapping in terms of energy is discussed as an alternative to the methods based on the frequency of events only

an alternative approach to probabilistic seismic hazard analysis in the aegean region using monte carlo simulation abstract the aegean is the most seismically active and tectonically complex region in europe damaging earthquakes have occurred here throughout recorded history often resulting in considerable loss of life the monte carlo method of probabilistic seismic hazard analysis psha is used to determine the level of ground motion likely to be exceeded in a given time period multiple random simulations of seismicity are generated to calculate directly the ground motion for a given site within the seismic hazard analysis we explore the impact of different seismic source models incorporating both uniform zones and distributed seismicity a new simplified seismic source model derived from seismotectonic interpretation is presented for the aegean region this is combined into the epistemic uncertainty analysis alongside existing source models for the region and models derived by a k means cluster analysis approach seismic source models derived using the k means approach offer a degree of objectivity and reproducibility into the otherwise subjective approach of delineating seismic sources using expert judgment similar review and analysis is undertaken for the selection of peak ground acceleration pga attenuation models incorporating into the epistemic analysis greek specific models european models and a next generation attenuation model hazard maps for pga on a rock site with a 10 probability of being exceeded in 50 years are produced and different source and attenuation models are compared these indicate that greek specific attenuation models with their smaller aleatory variability terms produce lower pga hazard whilst recent european models and next generation attenuation nga model produce similar results the monte carlo method is extended further to assimilate epistemic uncertainty into the hazard calculation thus integrating across several appropriate source and pga attenuation models site condition and fault type are also integrated into the hazard mapping calculations these hazard maps are in general agreement with previous maps for the aegean recognising the highest hazard in the ionian islands gulf of corinth and hellenic arc peak ground accelerations for some sites in these regions reach as high as 500 600 cm s 2 using european nga attenuation models and 400 500 cm s 2 using greek attenuation models

li ca enrichments in great scallop shells pecten maximus and their relationship with phytoplankton blooms article i nfo phytoplankton dynamics in coastal oceans is a major component of the global biogeochemical carbon cycle and is currently affected by global change through modifications in levels of primary productivity and com position of phytoplankton communities despite many attempts no straightforward geochemical proxy has been found yet in marine biogenic carbonates for reconstruction of past phytoplankton dynamics with high temporal resolution here we report on sub weekly variations of lithium to calcium ratios li cashell along the axis of maximum growth of great scallop shells pecten maximus collected alive between 1999 and 2007 in the bay of brest northwest france inter individual variability of li cashell time series was very low suggesting an environmental control on the incorporation of li within shells conversely inter annual variability of li cashell was high with limited seasonal li cashell variations in 2001 and 2007 and the presence of li enrichments from may to july in 1999 and 2004 comparison of these results with shell growth measure ments increment width and environmental parameters suggests i that shell calcification rate is likely the main factor controlling incorporation of li in pecten maximus shell calcite ii that seawater temperature has only a weak positive influence on li cashell of this species over the range 8 18 c and iii that during diatom blooms additional amounts of li may be trapped in the shell following dissolution of li rich frustules of ed ible species in the digestive tract of scallops being responsible for li cashell peaks therefore we suggest that li cashell ratio may be a novel proxy for timing and magnitude of diatom blooms in coastal ecosystems anal ysis of ancient shells may thus provide useful information on past phytoplankton dynamics and on the im portance of recent shifts observed from diatoms to non siliceous phytoplankton in coastal areas affected by anthropogenic activities

shells of the bivalve astarte moerchi give new evidence of a strong pelagic benthic coupling shift occurring since the late 1970s in the north water polynya climate changes in the arctic may weaken the currently tight pelagic benthic coupling in response to decreasing sea ice cover arctic marine systems are expected to shift from a sea ice algaebenth

the mean and seasonal circulation off southwest nova scotia abstract long term measurements off southwest nova scotia reveal the following features of the mean circulation a a westward longshore coastal current 4 10 cm s 1 b an anticyclonic gyre around brown bank 5 15 cm s 1 and c an upwelling circulation off cape sable 1 2 cm s 1 at bottom the gyre circulation appears permanent but the coastal current and upwelling exhibit annual variations of the same order as the means there is a distinct annual signal in the longshore transport at cape sable maximum westward in winter whereas the mean transport 0 14 106 m4 s 1 is consistent with both geostrophic estimates and budget requirements in the gulf of marine strong seasonal cycles are also found in the salinity and density fields at cape sable which appear to be controlled both by buoyancy input from the coastal current and local mixing effects a linear diagnostic model indicates that the primary dynamical balance for the circulation is between a longshore pressure gradient and longshore mean

the 8200 year b p event in the slope water system western subpolar north atlantic 1 stable isotope trace metal alkenone paleothermometry and radiocarbon methods have been applied to sediment cores in the western subpolar north atlantic between hudson strait and cape hatteras to reveal the history of climate in that region over the past 11 kyr we focus on cores from the laurentian fan which is known to have rapid and continuous accumulation of hemipelagic sediment although results among our various proxy data are not always in agreement the weight of the evidence alkenone sea surface temperature sst 18o and abundance of globigerinoides ruber indicates a continual cooling of surface waters over laurentian fan from about 18 c in the early holocene to about 8 c today alternatively mg ca data on planktonic foraminifera indicate no systematic change in holocene sst the inferred long term decrease in sst was probably driven by decreasing seasonality of northern hemisphere insolation two series of proxy data show the gradual cooling was interrupted by a two step cold pulse that began 8500 years ago and lasted about 700 years although this event is associated with the final deglaciation of hudson bay there is no 18o minimum anywhere in the labrador sea yet there is some evidence for it as far south as cape hatteras finally although the 8200 year b p event has been implicated in decreasing north atlantic ventilation and hence widespread temperature depression on land and at sea we find inconsistent evidence for a change at that time in deep ocean nutrient content at 4 km water depth

investigation of li ca variations in aragonitic shells of the ocean quahog arctica islandica northeast iceland interannual and intra annual variations in lithium to calcium ratio were investigated with high temporal resolution in the aragonitic outer shell layer of juvenile arctica islandica mollusca bivalvia collected alive in 2006 off northeast iceland li ca shell ranged between 7 00 and 11 12 mol mol 1 and presented well marked seasonal cycles with minimum values recorded at the annual growth lines a general pattern was a progressive increase in li ca shell from march to may followed by a plateau in june and a decrease down to minimum values in july august li ca shell was correlated with d 18 o shell derived temperature but the strength of this relationship was weak r 2 p shell in a islandica may most likely be explained 1 by calcification rate and or 2 by significant river inputs of li rich silicate particles flowing to the sea as soon as snow melts in the first case li ca shell may be a useful proxy for addressing seasonal variations of growth rate in bivalves that lack discernable microgrowth patterns abrupt decreases of li ca shell may in turn help identify growth retardations due to harsh environmental conditions alternatively if li ca shell variations are linked to particulate li inputs by rivers this could be a new proxy for the intensity of mechanical weathering of icelandic basalts with interesting perspectives for the reconstruction of frequency and intensity of past jokulhlaups subglacial outburst floods further works including experimental studies are needed to test these hypotheses

gulf of maine shells reveal changes in seawater temperature seasonality during the medieval climate anomaly and the little ice age article i nfo in this study we use subannually resolved oxygen isotope values of fossil dead collected and modern live caught bivalve shells arctica islandica l from the northwestern atlantic gulf of maine usa to reconstruct past seasonal changes in seawater temperature our results indicate decreased seasonal temperature amplitude of about 1 6 c or 21 during medieval times ca ad 1033 1062 compared to shells from the early little ice age ca ad 1321 1391 and during the late 19th century ad 1864 1886 additionally seasonal oxygen isotope data suggest that summers were cooler and winters were warmer in the gulf of maine during the 11th century compared to summers and winters in the 14th century and the late 19th century the inferred decreased seasonality during medieval times likely resulted from increased stratification of the coastal waters due to warmer seawater temperatures as seawater cooled during the little ice age we suggest that increased vertical mixing of the coastal surface waters was a major driving factor for the observed increase in the amplitude of the seasonal seawater temperature cycle

high resolution fault displacement mapping from three dimensional seismic data evidence for dip linkage during fault growth abstract detailed mapping using high resolution three dimensional seismic data has revealed a number of sub horizontal anomalies in the distribution of vertical displacement throw on the planes of growth faults in the gulf of mexico recognition of these anomalies is highly sensitive to the interval at which the fault displacements are sampled because they represent local decreases in throw which are confined to small discrete parts of the fault planes the distribution of the anomalies is inconsistent with model displacement fields of quasi elliptical concentric contours and is therefore incompatible with models of fault growth by uniform slip distribution and radial tip line propagation an alternative model is proposed whereby the evolution of a fault plane is established by the propagation and linkage of precursor fault segments in the dip direction dip linkage overlap and linkage of fault tips in the dip direction results in relay structures that are sub parallel to fault strike and therefore displacement minima that are sub horizontal on normal and thrust faults however since they are orthogonal to the main slip direction on the fault these structures have a low preservation potential and are therefore unlikely to be well resolved on cross sectional seismic profiles

the development of polygonal fault systems by syneresis of colloidal sediments abstract polygonal fault systems occur in numerous sedimentary basins worldwide are generally located on passive margins in onlap fill units and tend to comprise the finest grained sediments in this geological setting these fault systems have been most thoroughly described in the central north sea basin and the detailed structure shows a significant correlation with lithological variations both vertically and laterally extension measured in stacked decoupled tiers of polygonal faults correlates positively with both clay fraction and smectite content lateral facies variations are also observed and indicate that time equivalent sequences upslope from the smectite rich polygonally faulted sediments are coarse grained clay poor and undeformed this leads us to believe that the structure and geometry of the fault system are controlled by the colloidal nature of the sediments and that the volumetric contraction measured on seismic sections can be accounted for by syneresis of colloidal smectitic gels during early compaction syneresis results from the spontaneous contraction of a sedimentary gel without evaporation of the constituent pore fluid this process occurs due to the domination of interparticle attractive forces in marine clays dependent on environment and is governed by the change of gel permeability and viscosity with progressive compaction the process of syneresis can account for a number of structural features observed within the fault systems such as tiers of faults the location of maximum fault throw and growth components at upper fault tips as such this paper represents the first attempt to correlate microscale properties of clay rich sediments to their macroscale seismic character

sedimentology of the nw margin of the arabian plate and the sw ne trending nahr el kabir half graben in northern syria during the latest cretaceous and cenozoic abstract the late cretaceous maastrichtian to recent sedimentary record of nw syria documents the palaeoenvironments and regional tectonic setting during a time when the neotethys ocean to the north was closing culminating in regional collision by mid miocene time this detailed sedimentological study builds on a biostratigraphical framework established by russian workers during the mid maastrichtian the baer bassit ophiolite and related melange were emplaced southwards from neotethys onto the northern margin of the arabian african plate resulting in flexurally controlled deepening to the south after short lived emergence and erosion of emplaced units a renewed marine transgression ushered in shelf depth open marine carbonate deposition during the palaeocene early eocene this deposition was characterized by generally westward channelised mass flow from shallow marine carbonate banks to the east probably influenced by storm conditions flexurally controlled uplift and erosion took place during late eocene oligocene related to final closure of neotethys shelf depth carbonate deposition resumed during the aquitanian early miocene influenced by tectonic subsidence during the burdigalian a sw ne trending narrow up to 15 km wide linear 60 km long basin developed in the vicinity of the present day nahr el kabir river valley this basin is attributed to extension or transtension along the nahr el kabir fault this important lineament runs onshore from the southern limit of the cyprus arc tartous ridge through nw syria it is then offset by the dead sea transform in the ghab valley before merging with the south anatolian transform fault in turkey further northeast the basin in nw syria developed into the asymmetrical nahr el kabir half graben during the mid miocene with uplift of the northern margin and rapid fault controlled subsidence of the basin axis large volumes of terrigenous clastic and shallow marine bioclastic material were redeposited from the flanks into the axis of the basin mainly as gravity flows shelf depth carbonate deposition characterized both basin flanks especially the southern margin regression culminated in gypsum and marl precipitation in tectonically active local depocentres during the messinian salinity crisis pliocene re flooding established argillaceous shelf deposition within and around the pre existing basin coupled with local alkaline basalt volcanism and faulting in the southern coastal area regional regression gave rise to prominently channelised bioclastic sedimentation by the late pliocene the quaternary was marked by regional uplift and terracing influenced by glacio eustatic sea level change climatic change and further movement along the nahr el kabir fault the dominant control on basin development was thus local tectonics related to movements along the el kabir lineament and its interaction with regional scale tectonic events while eustasy played a subsidiary modifying role

reconstructing mid to high latitude marine climate and ocean variability using bivalves coralline algae and marine sediment cores from the northern hemisphere quantifying the role and contribution of the world s oceans in past present and future global change is an essential goal in climate paleoclimate and environmental studies although the global oceans interact and influence climate greatly the marine environment is substantially under represented in key climate assessment reports especially during the last millennium ipcc 2007 see palaeoclimate chapter 6 6 the last 2000 years the under representation of marine records in key climate documents likely results from the often imprecise chronologies associated with many marine based archives which greatly hinders singular climate comparisons lag lead phasing relationships with well dated and or annually resolved archives however several marine archive records have excellent chronological constraint in particular many marine bivalve taxa and coralline algae have annual increments that form within their carbonate framework that can be used to establish an absolutely dated chronology via cross dating techniques from the marine environment additionally in some cases where sedimentation rates are high and alternative chronological dating methods exist e g tephrochronology other than radiocarbon measurements often greater than 40 years uncertainty sediment archives can provide continuous sub decadal records of environmental change for centuries to millennia this brief introductory article and accompanying special issue will focus on the utilization of bivalves coralline algae and high resolution marine sediment cores in paleoclimate and environmental studies within the most recent millennium with a focus on the northern hemisphere

the southernmost margin of the tethys realm during the mesozoic and cenozoic initial geometry and timing of the inversion processes 1 along the northern border of africa pangea breakup has been diachronic during the jurassic the alpine tethys propagated northeastward from the atlantic to the alps during the permian the neo tethys propagated westward from oman to northwestern arabia then a secondary and late branch of neo tethys gave birth to the east mediterranean basin finally the two oceans connected at end of jurassic times achieving the development of africa northern plate boundary by the late cretaceous convergence between africa and eurasia led to the progressive closure of the tethys realm the continental collision is not completely achieved and the different segments of the confrontation zone maghreb central and east mediterranean zagros and oman expose different stages of the process however we emphasize the existence of synchronous geodynamic events from one end of the system to the other although they do not have the same meaning two of them are particularly important the campanian santonian c s event corresponds to 1 obduction and exhumation of high pressure low temperature metamorphic rocks around the arabian promontory 2 inversion along the margins of the east mediterranean basins and 3 lithosphere buckling in the atlas system maghreb and adjacent sahara platform the middle late eocene mle event corresponds to 1 the onset of collision at the northern corner of arabia 2 the onset of slab retreat in the mediterranean and 3 inversion along the margin of the east mediterranean as well as in the atlas the c s event coincides with a change in plate kinematics resulting in an abrupt increase of convergence velocity the mle event coincides with a period of strong coupling between the africa and eurasia plates and an abrupt decrease of convergence velocity in the middle of the system the central mediterranean seems to escape to the effects of convergence and is the site of quite permanent extensional movements since the triassic

a shell derived time history of bomb 14c on georges bank and its labrador sea implications bomb produced radiocarbon has been used in the past as an important tracer of ocean circulation and as a valuable tool for calculating co2 air sea exchange however previous studies of the ocean s time varying bomb 14c record have been confined exclusively to analyzing banded corals and thus their application has been limited to the lower latitudes the first time history of bomb 14c from the high latitude north atlantic ocean is obtained from a 54 year old mollusc specimen bivalvia arctica islandica which was collected live from georges bank 41 n in 1990 the annual growth bands of its shell were analyzed for 14c using accelerator mass spectrometry producing a 14c time history from 1939 to 1990 the depleted condition of the georges bank bomb 14c signal relative to two coral derived north atlantic 14c time histories suggests a significant deepwater source for the waters on georges bank supported by previous work linking the origin of waters on georges bank to the labrador sea the 14c budget on georges bank is modeled as labrador sea water which largely becomes confined to the shelf and partially equilibrates with the atmosphere during a 1 year transit time from the labrador sea to georges bank this model is also used to estimate a time history of bomb 14c for the labrador sea prebomb 14c values calculated for the surface labrador sea suggest that a greater inventory of bomb 14c has accumulated here than has previously been reported however the estimated prebomb average 14c 70 6 for this period is nearly identical to the 70 previously calculated for the prebomb source of north atlantic deep water and is in agreement with transient tracers in the ocean subsurface tritium data from the central labrador sea deduced variations in the ventilation and or 14co2 uptake rates in the labrador sea correspond with observed changes in surface salinity of the labrador sea suggesting a reduction in deepwater formation during the late 1960s and 1970s

a seismic hazard scenario for the main cities of crete island greece summary a probabilistic seismic hazard analysis is applied to the sites of the main cities chania rethymno and heraklion of crete island greece to compute probabilities of exceedance of specified values of peak ground acceleration pga and to estimate maximum possible pga at each site the methodology allows the use of historical or instrumental data or a combination of both the instrumental part of the data can be divided into subcatalogues with each having an individual minimum threshold magnitude for completeness also incorporated into the procedure were recently published maximum possible magnitudes for each site 6 48 5 21 7 52 for chania rethymno and heraklion respectively and an attenuation law for shallow seismicity in greece ln pga 3 52 0 70m w 1 14 ln r 2 h 2 1 2 0 12s 0 70 where r and h0 are respectively the epicentral distance and focal depth in kilometres s is 0 1 or 2 depending on soil conditions and pga is in units of cm s 2 the maximum pga for heraklion varies from 0 130g s 0 rock to 0 165g s 2 soft all three sites are coastal and alluvium is the dominant soil type for which s 2 probabilities that a given pga will be exceeded at least once during time intervals of 1 5 25 and 50 yr were also computed additionally maximum pga values associated with design earthquakes were computed for earthquakes at epicentral distances of 10 5 km median values of maximum pga were 0 23g 0 09g and 0 42g at chania rethymno and heraklion respectively

sedimentation processes in a tectonically active environment the kerkyra kefalonia submarine valley system ne ionian sea the kerkyra kefalonia valley system is the northwestern extension of the hellenic arc trench system representing the collision zone of the apulian platform and the hellenides the system is distinguished by two different physiographic regions the northern part u shaped and oriented nnw sse with relatively gentle slopes and a wide floor and the southern part oriented ne sw v shaped and with much steeper side walls and a narrow floor both parts are formed tectonically with the former coinciding with a collision zone and the latter being the morphometric expression of the kefalonia strike slip fault sediments recovered in the piston cores from the region consist of fine grained material deposited by a variety of sedimentation processes such as gravity driven mass movements associated with seismic activity i e slumping sliding debris flows grain flows turbidites seismoturbidites and to a lesser extent by hemipelagic deposition measured near bed currents and their associated shear stresses indicate resuspension of the material mainly within the northern part of the valley sub bottom acoustic seismic profiling data reveal various sedimentary provinces related to different mechanisms of sediment accumulation i the eastern margin of the apulian platform with hemipelagic sedimentation together with possible advection of suspensates from the adriatic in response localised to seabed erosion ii the western hellenic margin with down slope episodic sliding and slumping induced primarily by earthquake activity together with an input from hemipelagic settling iii the collision zone coinciding with the northern part of the kerkyra kefalonia valley system with deposition mostly from resuspension the occurrence of local mass gravity flows and the advection of some material from the north and iv the kefalonia strike slip fault region where mass gravity flows are the dominant mechanisms related to erosion deposition from resuspension overall sedimentation within the tectonically active kerkyra kefalonia valley system is characterised by the coupling of the mass gravity driven flows which are the predominant mechanisms with the near bed current regime related with resuspension phenomena and the advection of suspensates these latter mechanisms is likely more pronounced during the winter period when dense water masses formed in the adriatic inflowing into the ionian sea

using polygonal layer bound faults as tools to delimit clastic reservoirs in the levant basin offshore lebanon the levant basin offshore lebanon contains an array of layer bound normal faults in the oligocene miocene units the faults are believed to have nucleated in fine grained sedimentary rocks similar to polygonal fault systems worldwide and as a result they may be influenced by lithological heterogeneities in the host rock unit three dimensional seismic data and amplitude extraction from offshore lebanon were used to map deep water channels and fan lobes demonstrating that the distribution geometry and growth of the layer bound normal faults are affected by these sedimentary bodies which are impacting fault propagation three fault types are identified differentiated by their growth models and overall geometry type i faults in the deep basin indicate that a competent unit is present in the lower miocene and is affecting their growth type ii and iii faults in the latakia ridge and the margin respectively are smaller because of restriction by upper miocene and lower oligocene basin floor fans based on their seismic expression and on analogy with other basins containing similar faults it is very likely that the overlying and underlying units causing restriction consist of coarse grained clastic intervals therefore reservoirs offshore lebanon are probably lower miocene in the deep basin whereas in the latakia ridge and the levant margin reservoirs are in upper miocene and in lower oligocene units this study provides an additional evidence that layer bound or polygonal faults can have practical industrial application during exploration of hydrocarbons even in the absence of well data

gulf stream density structure and transport during the past millennium the gulf stream transports approximately 31 sv 1 sv 10 6 m 3 s 1 of water and 1 3 10 15 w of heat into the north atlantic ocean the possibility of abrupt changes in gulf stream heat transport is one of the key uncertainties in predictions of climate change for the coming centuries given the limited length of the instrumental record our knowledge of gulf stream behaviour on long timescales must rely heavily on information from geologic archives here we use foraminifera from a suite of high resolution sediment cores in the florida straits to show that the cross current density gradient and vertical current shear of the gulf stream were systematically lower during the little ice age ad 1200 to 1850 we also estimate that little ice age volume transport was ten per cent weaker than today s the timing of reduced flow is consistent with temperature minima in several palaeoclimate records implying that diminished oceanic heat transport may have contributed to little ice age cooling in the north atlantic the interval of low flow also coincides with anomalously high gulf stream surface salinity suggesting a tight linkage between the atlantic ocean circulation and hydrologic cycle during the past millennium

an intractable climate archive sclerochronological and shell oxygen isotope analyses of the pacific geoduck panopea abrupta bivalve mollusk from protection island washington state usa abstract annual growth increment patterns of cardinal teeth ct of panopea abrupta conrad can reportedly provide information about past climate variations however little is known about the intra annual timing and rate of shell growth necessary to interpret such records in addition it remains unclear whether actual temperatures can be reliably inferred from 18o values of geoduck goo e duk shells this study compared high resolution environmental records hourly to monthly resolved temperature bi weekly to monthly 18owater and salinity data with temperatures reconstructed from oxygen isotope values of the outer shell layer t 18oosl and cardinal tooth portions t 18oct of different contemporaneous specimens alive at the same locality results indicate that shell growth mainly occurred between march april and november december with a maximum during may august this finding must be considered when comparing the annual growth increment width chronologies to environmental parameters in addition intra annual 18oshell values require the calculation of weighted averages instead of arithmetic means during ontogeny the duration of the growing season remained nearly unchanged an important finding for paleoclimate studies based on inter annual growth patterns seasonal shell growth was strongly correlated with temperature r 0 93 r2 0 86 p

a 1600 year history of the labrador current off nova scotia a multicore from emerald basin on the conti nental margin off nova scotia has a modern 14 c age at the top and other 14 c dates indicate a linear sedimenta tion rate of 30 cm ka to 1600 calendar years bp this rate is great enough to record century to millennial scale changes in the surface and deep 250 m waters in the basin that are influenced by the labrador current we applied five proxies for seawater temperature changes to the sediments of emerald basin including the percent abundance and the oxygen isotope ratio d 18 o of the polar planktonic foraminifer n pachyderma s the unsaturation ratio of alkenones u k 37 produced by prymnesiophyte phytoplankton and the d 18 o and mg ca of benthic foraminifera all five proxies indicate the ocean warmed suddenly sometime in the past 150 years or so the exact timing of this event is uncertain because 14 c dating is inaccurate in recent centuries but this abrupt warming probably correlates with widespread evidence for warming in the arctic in the nineteenth century because the canadian archipelago is one of the two main sources for the labrador current warming and melting of ice caps in that region may have affected labrador current properties before this recent warming sea surface temperature was continually lower by 1 2 c and bottom water was colder by about 6 c in emerald basin these results suggest that there was no medieval warm period in the coastal waters off nova scotia because there is also no evidence of medieval warming in the canadian archipelago it seems likely that coastal waters from baffin bay to at least as far south as nova scotia were continually cold for 1500 of the past 1600 years

florida current surface temperature and salinity variability during the last millennium surface water d 18 ow near dry tortugas increased 0 4 during the course of the little ice age lia 1200 1850 a d equivalent to a salinity increase of 0 8 1 5 on the great bahama bank where surface waters are influenced by the north atlantic subtropical gyre d 18 ow increased by 0 3 during the last 200 years although a portion 0 1 of this shift may be an artifact of anthropogenically driven changes in surface water sco2 the remaining d 18 ow signal implies a 0 4 1 increase in salinity after 200 years b p the simplest explanation of the d 18 ow data is southward migration of the atlantic hadley circulation during the lia scaling of the d 18 ow records to salinity using the modern low latitude d 18 ow s slope produces an unrealistic reversal in the salinity gradient between the two sites only if d 18 ow is scaled to salinity using a high latitude d 18 ow s slope can the records be reconciled variable atmospheric 14 c paralleled dry tortugas d 18 ow suggesting that solar irradiance paced centennial scale migration of the inter tropical convergence zone and changes in florida current salinity during the last millennium citation lund d c and w curry 2006 florida current surface temperature and salinity variability during the last millennium paleoceanography 21 pa2009 doi 10 1029 2005pa001218

long term coordinated changes in the convective activity of the north atlantic the north atlantic is a peculiarly convective ocean the convective renewal of intermediate and deep waters in the labrador sea and greenland iceland sea both contribute significantly to the production and export of north atlantic deep water thus helping to drive the global thermohaline circulation while the formation and spreading of 18 degree water at shallow to intermediate depths off the us eastern seaboard is a major element in the circulation and hydrographic character of the west atlantic for as long as time series of adequate precision have been available to us it has been apparent that the intensity of convection at each of these sites and the hydrographic character of their products have been subject to major interannual change as shown by aagaard 1968 clarke et al 1990 and meincke et al 1992 for the greenland sea in the ows bravo record from the labrador sea eg lazier 1980 et seq and at the panulirus hydrostation s site in the northern sargasso off bermuda eg jenkins 1982 talley and raymer 1982 this paper reviews the recent history of these changes showing that the major convective centres of the greenland and labrador seas are currently at opposite convective extrema in our postwar record with vertical exchange at the former site limited to 1000 m or so but with labrador sea convection reaching deeper than previously observed to over 2300 m as a result greenland sea deep water has become progressively warmer and more saline since the early 70 s due to increased horizontal exchange with the arctic ocean through fram strait while the labrador sea water has become progressively colder and fresher over the same period through increased vertical exchange most recently convection has become deep enough there to reach into the more saline nadw which underlies it so that cooler but now saltier and denser lsw has resulted

observations of the eastern maine coastal current and its offshore extensions in 1994 cold surface temperatures reflecting scotian shelf origins and local tidal mixing serve as a tracer of the eastern maine coastal current and its offshore extensions which appear episodically as cold plumes erupting from the eastern maine shelf a cold water plume emanating from the eastern maine coastal current in may 1994 was investigated using advanced very high resolution radiometer avhrr imagery shipboard surveys of physical and biochemical properties and satellite tracked drifters evidence is presented that suggests that some of the plume waters were entrained within the cyclonic circulation over jordan basin while the major portion participated in an anticyclonic eddy at the distal end of the plume calculations of the nitrate transported offshore by the plume show that this feature can episodically export significant quantities of nutrients from the eastern maine coastal current to offshore regions that are generally nutrient depleted during spring summer a series of avhrr images is used to document the seasonal along shelf progression of the coastal plume separation point we speculate on potential causes and consequences of plume separation from the coastal current and suggest that this feature may be an important factor influencing the patterns and overall biological productivity of the eastern gulf of maine

the growth and propagation of synsedimentary faults abstract offset of each syn fault horizon across a synsedimentary i e growth fault records the throw subsequent to its deposition allowing successive growth stages of a fault to be determined this technique has been applied to synsedimentary faults mapped on 3d seismic datasets to distinguish between faults which propagated laterally during growth faults which did not propagate laterally for significant growth periods and faults in which the lateral dimensions of the active surface decreased during their growth these different fault tip line behaviours result in characteristic lateral and dip parallel fault displacement variations fault propagation rates have been measured for 10 fault tips the maximum propagation rate is 15 km my for gravity driven faults and 3 km my for tectonically driven faults rates of fault propagation decrease with elapsed time from the initiation of faulting with tip line stasis and retreat becoming dominant in the later stages of fault growth static and retreating lateral tip lines are associated with overlap of the fault strain field with that of a neighbouring fault most often with the formation of a fault relay zone

recent gravitative mass movements in a highly tectonically active arc system the hellenic arc abstract the hellenic arc system is located within one of the world s most seismically active areas and has experienced extreme tectonism throughout tertiary and quaternary times this paper discusses the various types of gravitative mass movements that have been detected and examines their causative factors in environments of high tectonic and seismic activity the areas surveyed are the sporadhes and corinth grabens in the back arc basin the zante cephalonia shelf on the inner slope of the hellenic trench and the kythera ridge in the outer island arc the various types of gravitative mass movements that have been documented include i sliding of large masses with no or only slight internal deformation ii sliding of masses with disintegration of the sediment fabric to debris flows and iii slow downslope creep the mass movements are associated with fault escarpments delta fronts and well stratified slopes with slope gradients ranging from 2 to 40 earthquakes seem to be the main mechanism initiating mass movement but other mechanisms such as increasing topographic gradient gas in the sediment pores and heavy rain can also independently trigger and or contribute to the initiation of mass movements

origin and nature of the rapid late tertiary filling of the levant basin the recent huge gas discovery in early miocene siliciclastics offshore israel highlighted a new world class gas province and has subsequently sparked great interest in the oligocene miocene deep water sediments of the levant basin based on a dense network of seismic data we present two fundamental observations first more than half of its sedimentary column accumulated within a mere 15 of the basin9s life span i e an 6 km thick section accumulated within 37 m y post middle eocene second this young section first accumulated in the deep basin and only then did large amounts of sediments amass along the eastern levant continental margin these fundamental observations allude to two feasible source to sink scenarios 1 the thick late tertiary section is composed of large amounts of terrigenous material that originated in arabia and was transported via the israeli margin and 2 the terrigenous material originated in africa and was transported northward via the region that eventually evolved into the nile river cone our data emphasize the difficulties of the first scenario and suggest that africa was the dominant sediment source this suggestion requires the submarine transport of sediments from offshore north africa to have been northeastward and thus raises new questions regarding ocean circulation at a time in which the neo tethys was closing and the marine connection to the mesopotamian basin gradually ceased

karst collapse susceptibility mapping considering peak ground acceleration in a rapidly growing urban area abstract karst collapse occurrences represent a geological hazard that can cause damage to man made structures in the present study a karst collapse susceptibility map was produced using a multivariate statistical method and a geographical information system the case under study is the northern suburbs of athens greece the karstic features of the study area were recorded physical processes slope angle and aspect hydrographic network springs lithology tectonic features along with anthropogenic road network and land use parameters were chosen as major factors affecting the karst collapse occurrences the innovative method was combining karst collapse occurrences with seismic hazard assessment which was achieved by calculating peak ground acceleration pga the pga was determined for a return period of 475 years corresponding to a 90 probability of not being exceeded in 50 years the logistic regression lr method was applied to evaluate these factors slope angle pga lithology and distance to springs and roads were statistically significant for the applied model among these factors the slope angle and pga have a negative effect while the lithology and distance to springs and roads have a positive effect on the karst collapse occurrences the validation of the applied lr model indicated that the results are reliable and that the produced map is accurate the karst collapse susceptibility map was classified into four classes the areas of very high and high susceptibility were observed mainly in the eastern and southwestern parts of the study area almost 30 of the existing urban growth boundary of the study area is located in areas of very high and high susceptibility the karst collapse susceptibility map can be used by planners and engineers for sustainable urban development