physical connectivity between pulley ridge and dry tortugas coral reefs under the influence of the loop current florida current system abstract the pulley ridge and dry tortugas coral reefs are among the most pristine but also fragile marine ecosystems of the continental united states understanding connectivity processes between them and with surrounding shelf and deep areas is fundamental for their management this study focuses on the physical processes related to the connectivity of these reefs unprecedented in situ time series were used at these specific reef locations together with satellite observations and numerical simulations to investigate the dynamics controlling local circulation on the southwestern florida shelf swfs under oceanic influence the approach of the loop current and florida current lc fc system to the swfs slope can induce 0 5 to 1 m s offshore flows impacting the pulley ridge and dry tortugas reefs on the other hand when the lc fc system retreats from the slope onshore flows can carry open sea waters over the coral reefs local formation of cyclonic eddies is possible near the dry tortugas reefs in the lc approach case and passage of upstream lc frontal eddies is possible in the lc retreat case offshore currents 1 m s over the swfs slope were also found during periods of anticyclonic lc eddy separation a novel finding is the shedding and northward propagation of mesoscale anticyclonic eddies from the core of the lc along the west florida shelf eddy shedding may have a broader effect on the dynamics of the shelf around the study reef areas long periods of lc fc domination over these coral reefs reaching several weeks to months are characterized by strong 1 m s along shelf currents and continuous upwelling processes which may weaken the slope stratification and bring colder deeper waters over the shelf break and toward the shallower shelf region

relative sea level rise and tidal development in the fundy tidal system previous studies of sea level and tidal amplification in the bay of fundy suggested a linear increase of tidal amplitude as relative sea level rose new data presented here are used in a numerical tidal model in an effort to reproduce paleotidal regimes over the last 7000 years five new sea level curves covering the last 4000 years and some previously published data extending the record back to 7000 years before present bp are used as the data base these data when used together with the tidal model indicate that tidal amplitudes increased much more rapidly between 7000 and 4000 years ago than in the period 4000 years ago to present it is also shown that changes in depth within the bay of fundy produce little effect on the tidal amplitudes whereas such variations in water depth on georges bank account for almost all the change this calculation of tidal amplitude changes allows calibration of sea level curves to be made for the bay of fundy using higher high water hhw indicators

how many oceans meliata vardar and pindos oceans in mesozoic alpine paleogeography the timing of rifting and subduction in the meliata vardar and pindos zones of the hellenic dinaric carpathian region indicates that they cannot be considered remnants of a single ocean basin in contrast to several recently published mesozoic paleogeographies sea floor spreading in the meliata zone culminated in middle triassic ladinian time and ceased in the late triassic and subduction occurred from this time until late jurassic closure in contrast sea floor spreading in the vardar zone began in early jurassic time and culminated in the middle jurassic and subduction occurred from latest jurassic time in the pindos zone sea floor spreading was initiated in the early triassic with late jurassic and early tertiary subduction

loop current eddy shedding estimated using geosat altimeter data a method for extracting periodic signals from altimeter data is applied in the gulf of mexico using data from the first two years of the geosat exact repeat mission the least squares fitting of selected frequencies of sine and cosine functions to the time series of sea surface height at each point of the geosat ground track is used to estimate the dominant frequency in the gulf for this time period optimal interpolation of the sine and cosine coefficients at the dominant frequency to a uniformly spaced grid allows reconstruction of the time series in the gulf and shows eddies shedding from the loop current with a period of approximately 10 5 months consistent with shedding periods determined from numerical models and analysis of satellite infrared data this technique is a novel method for investigation of periodic signals in geosat altimetry and is not severely affected by the data outages present in the time series

three dimensional p wave velocity image under the carpathian arc abstract an inversion of p wave travel time residuals from selected earthquakes in the distance range 30 98 to two seismic station networks was used to model p wave velocity anomalies down to 250 km depth in the first inversion experiment a region between 43 5 47 5 n and 21 29 e was modelled using 35 seismic stations while in the second one a region between 44 47 n and 25 29 e was modelled using 19 seismic stations the 4 layer block model of the first inversion offers 19 reduction in residual variance while the 5 layer block model of the second one offers 26 reduction the rest being explained by noise and smaller scale heterogeneities the obtained velocity anomalies correlate remarkably well with the gravity anomalies and with the tectonic model for the vrancea region of fuchs et al 1979

neogene kinematics of the transylvanian basin romania the transylvanian basin is a major sedimentary basin located in the eastern part of the european alpine orogenic system it has a sedimentary fill more than 5 km up to 8 km in some small areas thick of upper cretaceous to upper miocene deposits it represents the main gas producing province in romania and central eastern europe in this article we analyze seismic lines and structural data from the basin as well as from its northern eastern and southeastern borders these data indicate a tectonic origin for the neogene structures from the transylvanian basin these structures include 1 northeast and southwest dipping thrust faults and 2 east northeast and west northwest striking strike slip faults having normal or reverse slip secondary structures such as salt diapirs and folds are related to these faults structural data from the basin and its border indicate a neogene overall compressional transpressional regime having maximum principal stress oriented north to northeast daniel ciulavu received a diploma in geology and geophysics at the university of bucharest in 1989 and his ph d in geology at the vrije universiteit amsterdam netherlands in 1999 he worked two years for geasol s a romania in hydrogeology coal and alluvial gold exploration since 1991 he has been on the staff of the university of bucharest where he teaches the courses on structural geology in the department of geophysics and kinematic analysis for master s students corneliu dinu received a diploma in geology in 1966 and his ph d in 1976 at the university of bucharest romania after graduation he worked as field geologist for prospectiuni s a romania since 1970 he has been on the staff of the university of bucharest where he is professor of structural geology and basin analysis since 1990 he has served as the dean of sciences at the faculty of geology and geophysics university of bucharest alexandru szakacs received a diploma in geology in 1974 and his ph d in 2000 at the university of bucharest romania he is senior geologist at the romanian institute of geology he has 25 years of experience in studying the neogene volcanism of the carpathian pannonian area he has also worked on the neogene volcanism of the cordillera betica spain dorin dordea received a diploma in geology in 1974 at the university of cluj romania his field of activity is remote sensing he has worked in several areas in africa and romania since 1999 he has served as the chief geologist of prospectiuni s a bucharest romania he is now working on the application of remote sensing in mining exploration

the deglaciation of atlantic canada as reconstructed from the postglacial relative sea level record the post wisconsinan relative sea level record from atlantic canada is used to reconstruct the morphology of late wisconsinan age ice cover during its retreat from the atlantic region the proposed reconstruction has little or no grounded ice in the southern gulf of st lawrence an ice dome over the north shore of the st lawrence and thin ice often less than 1 km thick over much of the rest of the area a sensitivity analysis shows that the proposed reconstruction is not unique in its ability to account for the relative sea level record but that the thickness of ice in any individual area of the reconstruction is unlikely to be in error by more than a factor of two the exact position of the ice margin in some areas is not well constrained by the model an example is in southeastern newfoundland the numerical model used to relate ice morphology to postglacial relative sea level assumes that the ice sheets are isostatically equilibrated at the glacial maximum and therefore that load changes associat

an upwelling case study on florida s west coast using a combination of satellite sea surface temperature imagery in situ currents temperature and sea level data and a numerical circulation model we describe an upwelling event observed along florida s west coast although ubiquitous features of continental shelves descriptions of coastal upwellings or downwellings are generally complicated by the continuum of processes in which they occur for the case study presented the winds were light and the baroclinic background currents were steady for several days prior to the event these conditions allow the evolution of a specific winddriven upwelling event to be viewed as an initial value problem the data and the numerical model analysis show that the route of adjustment by the sea level and currents is a classical ekman geostrophic one sea level drops due to an offshore ekman transport causing a geostrophic alongshore jet and the associated onshore flow within the bottom ekman layer accounts for the appearance of cold water at the surface this surface manifestation occurs as an elongated feature centered about the 25 m isobath that spans roughly half of the florida peninsula from just north of tampa bay to key west the coldest water is observed offshore from tampa bay and we explain this region of locally maximum upwelling on the basis of the coastline and isobath geometries

ice age paleotopography a gravitationally self consistent theory of postglacial relative sea level change is used to infer the variation of surface ice and water cover since the last glacial maximum lgm the results show that lgm ice volume was approximately 35 percent lower than suggested by the climap reconstruction and the maximum heights of the main laurentian and fennoscandian ice complexes are inferred to have been commensurately lower with respect to sea level use of these ice age boundary conditions in atmospheric general circulation models will yield climates that differ significantly from those previously inferred on the basis of the climap data set

the dynamics of the mississippi river plume impact of topography wind and offshore forcing on the fate of plume waters 1 high resolution numerical simulations of the northern gulf of mexico region using the hybrid coordinate ocean model hycom were employed to investigate the dynamical processes controlling the fate of the mississippi river plume in particular the conditions that favor cross marginal transport the study focuses on the effects of topography wind driven and eddy driven circulation on the offshore removal of plume waters a realistically forced simulation nested in a data assimilative regional gulf of mexico hycom model reveals that the offshore removal is a frequent plume pathway eastward wind driven currents promote large freshwater transport toward the shelf break and the desoto canyon where eddies with diameters ranging from 50 to 130 km interact with the buoyant plume and effectively entrain the riverine waters our estimates show that the offshore removal by eddies can be as large as the wind driven shelf transport the proximity of eddies to the shelf break is a sufficient condition for offshore removal and shelf to offshore interaction is facilitated by the steep bottom topography near the delta strong eddy plume interactions were observed when the loop current system impinged against the shelf break causing the formation of coherent narrow low salinity bands that extended toward the gulf interior the offshore pathways depend on the position of the eddies near the shelf edge their life span and the formation of eddy pairs that generate coherent cross shelf flows this study elucidates the dynamics that initiate a unique cross marginal removal mechanism of riverine low salinity nutrient rich waters allowing their export along connectivity pathways induced by a large scale current system

glacial isostatic deformation of the great lakes region tilting of ancient shorelines of the great lakes region has been studied for more than a century nevertheless fundamental disagreements exist among both glacial geologists trying to understand the chronology of lake events geophysicists investigating the causes of tilting and glaciologists attempting to reconstruct ice sheet thickness along the southern perimeter of the laurentide ice sheet fundamental to many of these studies is the belief that the southern part of the great lakes region has been geodynamically stable for at least the past 11 000 yr results of our numerical model of the glacio isostatic process for a spherical layered self gravitating viscoelastic earth suggest constraints upon earth models shoreline chronologies and ice sheet thickness as a test of the model predictions were compared to observations of outlet chronology and isobases of both ancient shorelines and modern tilting indicated by lake level gauges earth models with a uniform viscosity mantle resulted in the best fit to observed shorelines earth models with a low viscosity asthenosphere or a high viscosity lower mantle do not predict deformation consistent with known outlet chronologies an ice sheet with thickness of 2 000 m over the region results in an excessive amount of tilting in most instances whereas a much thinner ice sheet 700 m although in better agreement with the data generally resulted in underestimates none of the results suggests stability in the southern great lakes region at any time predictions indicate instead that submergence of ancient shorelines has complicated the record there

observations of currents on the west florida shelf break year long measurements by five acoustic doppler current profilers moored across the central west florida shelf wfs and shelf break reveal new information on the local velocity structure and its temporal evolution the moorings were between the 30 and 300 m isobaths at depths greater than about 100 m the currents were sometimes directly affected by the deep ocean during the measurement period the loop current lc directly impacted the central wfs three times amounting to a total of about 13 of the year for the remainder of the year the shelf break currents had equal likelihood of flowing northward or southward northward currents achieved over 70 cm s and the southward currents driven by the lc achieved 120 cm s neighboring instruments recorded strong 30 cm s currents flowing in opposite directions current reversals in one case totally nearly 100 cm s within a few days were also found

simulating the dynamics and intensification of cyclonic loop current frontal eddies in the gulf of mexico 1 the dynamics associated with the loop current lc variability in the gulf of mexico gom are studied using a 5 year free running numerical simulation with the hybrid coordinate ocean model hycom the dynamics of major gom circulation features are represented the extension of the lc and the associated anticyclonic warm core loop current eddies lces and cyclonic loop current frontal eddies lcfes the study focuses on the dynamics of the lcfes and their role during the lces shedding which dramatically affects the gom circulation we analyze several characteristics of the lc frontal dynamics modeled lcfes have a coherent vertical structure which extends to the deep layers of the gom they may split in two separate upper and lower layer eddies deep and surface remnants from different frontal eddies are able to align to form new coherent structures lcfes intensify along the extended lc northern edge when flowing over the deep northern gom shelf slope that forms the mississippi fan through a promontory effect in which the incoming cyclone aggregates positive potential vorticity anomalies in lower layers leading to the intensification of the whole vortex structure lcfes may also expand further along the lc path by horizontal vortex merging when they are blocked between the lc and the northeast corner of the continental shelf in the gom the intensification and merging due to topographic effects explain the enlarged frontal eddies observed on the eastern side of the loop current these larger eddies further migrate along the lc front and may play a role in the shedding sequence

erratum postglacial relative sea level change port au port area west newfoundland we first report pollen and foraminifera analyses and radiocarbon dates from two cores taken from salt marsh deposits bordering port au port bay southwestern newfoundland results show that relative sea level rsl stood at 2 8 m below present higher high water level hhwl at 2770 300 years bp and at 1 8 m at 2365 175 years bp at the core sites they permit calculation of a rate of late holocene rsl change from western newfoundland we then report other available dates bearing on the earlier rsl record of this area a date of 5800 200 years bp fixes the age of minimum rsl in port au port bay at 11 14 m below present a date of 9350 120 years bp from st george s provides a minimum age for the passage of sea level below present there a date of 12 600 140 years bp from stephenville fixes a sea level at 29 m above present whereas one of 13 600 110 years bp from abrahams cove dates the marine limit at 44 m these geographically restricted data closely constrain a curve of postglacial rsl change

deglaciation induced vertical motion of the north american continent and transient lower mantle rheology the last deglaciation event of the current ice age which began approximately 18 000 years ago and ended about 7000 years ago continues to exert a profound influence on the vertical motion of the solid earth in and surrounding the regions which were once ice covered observations of such vertical motions may be employed to constrain the radial viscoelastic structure of the planet and therefore to contribute in an important way to the understanding of geodynamic processes in general in this paper both present day rates of vertical motion as recorded on tide gauges and long time scale records of vertical motion as recorded in 14c controlled relative sea level histories are employed to refine previously constructed models of the radial viscoelastic structure an interesting sidelight to this analysis is the demonstration that the lower mantle viscosity inferred from the vertical motion data could represent a transient rather than the steady state value a fact which would help considerably to reconcile the small viscosity stratification required by the glacial rebound data with the large stratification which seems to be required by some recent analyses of the geoid height anomalies associated with internal density heterogeneity of the mantle which has been revealed by application of seismic tomographic techniques a further product of these new analyses is obtained by the application of the glacial isostatic adjustment model to filter this signal from the secular trends of relative sea level observed on tide gauges from both the east and west coasts of the north american continent these results may be important in the context of recently proposed scenarios of climatic change

evidence for a high velocity slab associated with the hindu kush seismic zone we used teleseismic travel time residuals to determine lateral velocity variations of the crust and upper mantle in the pamir hindu kush region in tadjikistan and afghanistan data from 29 analog seismic stations in tadjikistan and northern afghanistan were used to determine travel time residuals for 210 teleseismic events ranging in distance from 28 to 87 and covering a broad range of azimuths we inverted for velocity perturbations over a rectangular grid with a block size of 99 99 km the model extended to a depth of 350 km with a 50 km thick first layer and two 150 km thick deeper layers the results show a strong and well resolved zone of high velocities in the upper mantle at depths greater than 200 km coincident with the location of the hindu kush seismic zone no clear velocity perturbations are associated with the pamir seismic zone above 200 km little correlation is observed with the seismic zone but indications of thicker crust under the pamir and thinner crust under the tadjik depression are seen the high velocities are most likely caused by the presence of oceanic lithosphere at depth

frequency of ring separations from the loop current in the gulf of mexico a revised estimate the most energetic events in the circulation of the gulf of mexico are the separation of large anticyclonic rings from the loop current building on previous work the authors examine all the apparent rings since july 1973 this new dataset includes the satellite altimetry since 1992 providing a set of 34 consecutive ring formations the primary advantage of altimetry is that the data remain available in the summer one finding is that the ambiguity of whether or not a ring has separated is reduced but not eliminated the uncertainty with which separation events can be specified remains approximately 4 weeks even with nearly continuous data primary peaks in the distribution of separation intervals are found at 6 and 11 months with a smaller peak at 9 months if the spectrum is smoothed heavily enough a peak in the distribution can be formed nearer 12 months but this near annual peak is a result more of the smoothing than of the data

kinematic evolution of the romanian carpathians abstract the regional pattern of contraction and extension directions and the evolution of the strain field from paleogene to neogene times enabled a reconstruction of the migration path of the carpathian collision front the carpathian nappes were thrust around the moesian plate during paleogene and early neogene times and protruded into a small oceanic embayment between the moesian and european plates the arc structure of the carpathian fold thrust belt was formed in late neogene times as a result of the eastward escaping tisza dacia block due to n directed convergence of the adriatic plate and the retreating subduction of an oceanic slab brittle deformation structures in the romanian carpathians suggest three tectonic events related to major plate motions 1 paleogene to middle miocene ne to ene contraction caused right lateral curved strike slip faults 2 middle miocene to pliocene fan shaped orientations of contraction directions were caused by right lateral oblique convergence in the southern carpathians frontal convergence in the southern eastern carpathians and left lateral convergence in the northern eastern carpathians 3 pleistocene to holocene general e w extension and n s contraction in the carpathian arc and local ese wnw contraction in the vrancea area is related to the late roll back stage and break off of the subducted slab in the bend area

tertiary subduction and slab break off model of the carpathian pannonian region abstract this paper illustrates the application of multidisciplinary data analysis to the carpathian pannonian region and presents a new tertiary development model that incorporates all multidisciplinary parameters during the late cretaceous eocene the future carpathian orogen was part of the larger alpine carpathian orogen formed by the southeastward subduction 135 55 ma of the penninic ocean and the ultimate collision 55 40 ma of the european and adriatic continents the subduction in the alpine region ended by the slab break off of the subducting oceanic lithosphere from the continental one and by the related magmatism 43 24 ma while the eocene alps were under continental collision the eocene remnant carpathian flysch basin rcfb was still subducting the carpathians and eastern parts of the alps started to occupy the region of the present carpathians during the early miocene the oceanic plate underlying the rcfb subducted southwestwards later westwards while the northeastward and eastward migration velocity of the accreting plate boundary decreased through time the slower subduction rate caused a steeper dip of the subducting slab the beginning of the eggenburgian 22 19 ma and following duration of extension in the orogenic hinterland accompanied by the asthenosphere upwelling the onset of the crustally derived volcanism above the risen asthenosphere and the younger mantle derived volcanism progressively less contaminated by the crustal material all contemporaneous with a shortening in the carpathian accretionary wedge the subduction of the rcfb finally led at the end of the early miocene to a collision with the continental margin along the westernmost part of the present carpathian arc the subduction roll back of the subducting slab of the rcfb under the advancing inner carpathians the oblique closure of the basin the progressive change of the subduction to collision from the west to the east along the carpathian arc drove a scissors like break off of the subducting oceanic slab along the west carpathians the break off in the east carpathians was driven by the weight of a subducting oceanic slab and buoyancy of the attached continental slab the break off started in the west of the carpathian arc in the early miocene ran along the arc to its present position in the bend area between the east and south carpathians and separated the oceanic slab that subducted passively under its own weight from the european continental margin the lateral propagation rate of the slab tear decreased with time the break off related volcanism was synchronous with the final stages of the collision

tertiary tectonic evolution of the external east carpathians romania abstract paleostress calculation and analysis of mesoscopic structures are integrated with depth interpreted geological profiles based on seismic studies and well correlation to derive a tertiary tectonic model for the east carpathians following early miocene and older orogenic phases the first tectonic event that affected the studied area is characterised by a wsw ene oriented shortening of middle miocene late burdigalian in age resulting deformations induced ene ward thrusting of tarcau and marginal units as well as the internal part of the subcarpathian nappe a second shortening event with an e w to wsw ene contraction direction took place in the late miocene sarmatian characterised by further foreland thrusting of the subcarpathian nappe and out of sequence deformation in the tarcau and marginal folds nappes along strike differences in deformation mechanisms are controlled by the friction coefficients along the main detachment layers by the lateral variations in the wedge thickness and by the involvement in the northern part of the thrusting system of the thick competent east european platform tear faulting occurred in both tectonic events the main resulting structure being the triangle zone developed south of the trotus valley the latest miocene latest sarmatian early pliocene is characterised by a strike slip stress field with nne ssw compression and wnw ese tension axis left lateral faults being dominant the last deformation which affected the studied area is characterised by nnw sse shortening during the pliocene major deformations taking place mainly in the sw most bending zone

some seismic signatures in the romanian crust abstract some new seismic reflection data in the w of the moesian platform focsani depression and transylvania depression show seismic patterns which reflect the local structure and evolution of the each area these local areas were affected by subsidence which over printed the changes on the old pattern the old and more or less reflective lower crust was fractured and some rigid blocks have preserved the reflectivity up to the present the ba ilesti section illustrates a transparent or diffractive upper crust and a well marked lower crust by an alternation of reflective and non reflective zones the crystalline crust of the r mnicu sa rat section has two patterns one relatively reflective near the bottom of the depression the w side whilst the other on the e flank of depression is transparent the e flank seems to be more fractured due to some tensile fractures originating in the bending stress during subsidence the t rgu muressection has a specific crustal pattern a near transparent crystalline crust overlies a very large crust mantle transition zone which is fragmented in alternated reflective and transparent blocks

glacioisostatic influences on virginia s late pleistocene coastal plain deposits abstract the late pleistocene of virginia s outer coastal plain consists of sediments dated to marine isotope stages mis 5 and 3 two members from the tabb formation south of the chesapeake bay in southeastern virginia and two formations east of the bay on the southern delmarva peninsula were dated using optically stimulated luminescence osl the stratigraphically older butlers bluff member yielded osl ages of 70 ka 62 78 ka mis 5a and the younger poquoson member and wachapreague formation mis 3 ages of approximately 43 ka 33 50 ka and 42 ka 33 54 ka respectively these shoreface and near shore geologic units reached maximum altitudes ranging from 3 to 12 m above present sea level and were deposited when established glacial eustatic sea level curves suggest that sea levels were significantly lower than present by approximately 40 m if these new ages and the sea level curves are correct there must have been regional uplift of more than 40 m probably due to isostatic adjustments of forebulges peripheral to north american ice sheets when they were at their maxima during mis 6 and mis 2 if the late mis 6 forebulge collapse continued throughout mis 5 and mis 4 we propose that regional land elevations may have been low enough for deposition to occur during the lower eustatic sea levels of mis 3 during late mis 3 the units experienced renewed uplift followed by subsidence to present day elevations if this paraglacial region is not yet in isostatic equilibrium and still requires further forebulge subsidence this could explain the present day altitude and age discrepancies associated with these relict marine deposits

kinematics of the alpine west carpathian orogen and palaeogeographic implications we present the euler rotations of the plates involved in the alpine west carpathian orogen the rotations are defined to a large extent by the magnetic anomalies of the atlantic ocean a few extra rotations occurred during two collisions and a mid cretaceous event at variance with earlier reconstructions we additionally control the rotations by the orientation of palaeomagnetic declinations the plate rotations are integrated into a model illustrated by palaeogeographical maps special features of the model are 1 subdivision of the northern margin of adria into the two plates pelso and austroalpine west carpathia on the basis of palaeomagnetic data 2 eohellenic obduction of meliata units onto the eastern margins of pelso and austroalpine west carpathia from the tethys side 3 first eoalpine collision of the marginal plates of adria with tisza far off the west european plate margin 4 a 80 90 rotation of austroalpine west carpathia during the eoalpine collision 5 subdivision of the neoalpine collision into a palaeogene stage of predominantly strong se nw shortening and a neogene stage of predominantly lateral extrusion westward and eastward in principle the maps show quantitative ocean spreading subduction and plate rotations however possible modifications of the model discussed in this paper limit the quantitative evaluation

impact of caribbean cyclones on the detachment of loop current anticyclones 1 the western boundary current in the north atlantic is characterized by an intense flow reaching 2 5 ms 1 at the surface that enters the caribbean sea through the lesser antilles passages crosses the entire caribbean and enters the gulf of mexico through the yucatan channel where it is known as the loop current a characteristic feature of the loop current is eddy shedding events i e the detachment of large anticyclonic eddies at irregular intervals moored current measurements between january 2005 and july 2009 in the loop current the yucatan channel and the caribbean coastal waters of mexico i e the western cayman sea along with aviso altimetry are used to evidence the northward propagation of cyclonic anomalies along the caribbean coast of mexico and the marked eastward displacement of the loop current at 23 n latitude just before several anticyclonic eddy shedding events after entering the gulf of mexico these cyclonic anomalies might initiate or enhance existing campeche bank cyclonic eddies which are related to many of the loop current detachment events sixteen of the twenty one detachments that occurred during the study period 76 are related to the cyclonic eddies in the western caribbean sea six of them were not reattached again to the loop current observations thus clearly indicate that cyclonic eddies in the western cayman sea contribute significantly to the loop current eddy shedding process which is complex and in principle not unique

late quaternary relative sea level change in the western gulf of maine evidence for a migrating glacial forebulge new radiocarbon dated cores obtained by vibracorers in the western gulf of maine confirm that a short lived relative sea level lowstand of 55 m occurred at 11 10 5 ka these cores and younger salt marsh data also reveal that rates of transgression varied throughout the holocene probably due to local variations in glacial isostasy the isostatic component is resolved by subtracting published approximations of eustatic sea level from our well determined observations of local relative sea level a large peak in the isostatic curve coincides with the lowstand and is interpreted as a forebulge 20 25 m in amplitude forebulge migration is estimated at 7 11 km 100 yr based on the timing of lowstands across the region

loop current boundary variations the periodicity of warm ring separation from the loop current and the characteristics of cold perturbations found along the loop current boundary were studied using a long term data set made up of noaa satellite infrared images the results showed that the period between separation of warm rings from the loop current was highly variable the average period was about 10 9 months the minimum period was 6 months and the maximum period was 17 months for the data set used ring separations occurred most often in the winter the study of the cold perturbations indicated that these perturbations were most pronounced along the northern and eastern portions of the loop current boundary and were less pronounced south of 27 n along the western boundary the data suggested that the perturbations either formed or intensified in the northwestern portions of the boundary the large effects along the eastern boundary of the loop current were thought to be associated with the movement of the intense perturbations that are initially found along the northwestern portions of the boundary

separation of warm core rings in the gulf of mexico abstract the separation of anticyclonic rings is studied using a 12 level primitive equation numerical model of the western north atlantic the gulf stream formation region model is based on the bryan cox semtner code and uses degree horizontal resolution the eastern boundary of the model near the mid atlantic ridge is forced by a pumps and baffles region to have the appropriate temperature and salinity structure vertical shear and total transport the model is closed by a solid northern wall at 36 n and is forced by steady winds in the results presented here large rings separate from the loop current in the gulf of mexico at periods near 30 weeks the separation of a single typical ring is shown in detail the most striking feature is that the separation is not a single spectacular event but a long gradual process involving recirculation between the ring and the main flow for many weeks after the time at which one would on the basis of standard observational evidence normally believe the

vrancea99 the crustal structure beneath the southeastern carpathians and the moesian platform from a seismic refraction profile in romania the vrancea99 seismic refraction experiment is part of an international and multidisciplinary project to study the intermediate depth earthquakes of the eastern carpathians in romania as part of the seismic experiment a 300 km long refraction profile was recorded between the cities of bacau and bucharest traversing the vrancea epicentral region in nne ssw direction the results deduced using forward and inverse ray trace modelling indicate a multi layered crust the sedimentary succession comprises two to four seismic layers of variable thickness and with velocities ranging from 2 0 to 5 8 km s the seismic basement coincides with a velocity step up to 5 9 km s velocities in the upper crystalline crust are 5 9 6 2 km s an intra crustal discontinuity at 18 31 km divides the crust into an upper and a lower layer velocities within the lower crust are 6 7 7 0 km s strong wide angle pmp reflections indicate the existence of a first order moho at a depth of 30 km near the southern end of the line and 41 km near the centre constraints on upper mantle seismic velocities 7 9 km s are provided by pn arrival times from two shot points only within the upper mantle a low velocity zone is interpreted travel times of a plp reflection define the bottom of this low velocity layer at a depth of 55 km the velocity beneath this interface must be at least 8 5 km s geologic interpretation of the seismic data suggests that the neogene tectonic convergence of the eastern carpathians resulted in thin skinned shortening of the sedimentary cover and in thick skinned shortening in the crystalline crust on the autochthonous cover of the moesian platform several blocks can be recognised which are characterised by different lithological compositions this could indicate a pre structuring of the platform at mesozoic and or palaeozoic times with a probable active involvement of the intramoesian and the capidava ovidiu faults especially the intramoesian fault is clearly recognisable on the refraction line no clear indications of the important trotus fault in the north of the profile could be found in the central part of the seismic line a thinned lower crust and the low velocity zone in the uppermost mantle point to the possibility of crustal delamination and partial melting in the upper mantle

a loop current intrusion case study on the west florida shelf the gulf of mexico loop current intruded upon the west florida continental shelf in june 2000 in situ currents and hydrography along with satellite temperature and altimetry measurements are used to describe this event and its effects on the shelf a strong southward current is observed to flow along the shelf slope seaward of the intruded water boundary this current transported cold nutrient rich water from the north thereby producing anomalous hydrographic features near the shelf break 80 m isobath an array of moored velocity profilers reveals that the currents landward of the intruded water are independent of the loop current and primarily driven by local winds a series of idealized numerical model simulations inclusive of forcing by both the loop current and local winds confirm the observational findings that the shelfbreak currents are largely loop current controlled while the shelf currents are largely controlled by the local winds

the crustal structure beneath se romania from teleseismic receiver functions summary due to vigorous neogene geodynamic processes including oceanic subduction slab break off and mountain building in the carpathian arc the architecture of the lithosphere in romania is quite complicated to improve the knowledge about the lithosphere asthenosphere system in this region the passive seismological calixto99 experiment was conducted in 1999 in the se part of romania here we present crustal models derived from the analysis of teleseismic recordings with the receiver function rf method of the 120 temporarily installed stations and of the permanent geofon stations mlr and tirr the rf results extend the known crustal models which are based mainly on seismic refraction work and analysis of regional earthquakes we apply a grid search inversion at 30 stations and use two different error estimation methods to determine the moho depth and the average crustal vp vs ratio the complex 3 d intracrustal structure especially the deep sedimentary basins distorts significantly the rf waveforms within the whole station network this leads to ambiguous results at some stations our model of the moho depth has a maximum crustal thickness in the se carpathian mountains at station mlr with a depth of about 45 km and an average crustal vp vs ratio of 1 79 the surrounding crust in se romania has a thickness of mainly 35 40 km the rfs at mlr are characterized by clear azimuthal effects that can be correlated with the variation of the sediment thickness in the foredeep of the carpathian mountains a rf waveform inversion verifies these results and gains improved 1 d s wave velocity models at several stations in se romania

peatland development at the arctic tree line quebec canada influenced by flooding and permafrost in this study we documented the holocene history of a peat plateau at the arctic tree line in northern quebec using stratigraphic and macrofossil analyses to highlight the effects of geomorphic setting in peatland development paludification of the site began about 6800 cal yr bp from 6390 to 4120 cal yr bp the peatland experienced a series of flooding events the location of the peatland in a depression bounded by two small lakes likely explains its sensitivity to runoff the proximity of a large hill bordering the peatland to the south possibly favored the inflow of mineral laden water the onset of permafrost aggradation in several parts of the peatland occurred after 3670 cal yr bp uplifting of the peatland surface caused by permafrost stopped the flooding according to radiocarbon dating of the uppermost peat layers permafrost distribution progressed from the east to the west of the peatland indicating differential timing for the initiation of permafrost throughout the peatland most of the peatland was affected by permafrost growth during the little ice age picea mariana macroremains at 6450 cal yr bp indicate that the species was present during the early stages of peatland development which occurred soon after the sea regression

holocene relative sea level fluctuations in the st lawrence estuary quebec canada abstract between 7000 and 6000 yr b p relative sea level was as much as 5 m lower than today in the st lawrence estuary quebec a small transgression laurentian transgression occurred between 5800 and 4400 yr b p which resulted in the construction of an 8 to 10 m terrace about 3000 yr b p relative sea level was similar to present and then a stillstand or a slight rise occurred during which a cliff micmac cliff was cut into the emerged terrace during a subsequent lowering of relative sea level coastal emergence a low aggradational terrace mitis terrace was built between 2300 and 1500 yr b p at the base of the micmac cliff a new emergence curve for the south shore of the st lawrence estuary showing a mid holocene high stand of relative sea level is therefore proposed

deep seismic soundings in romania this paper describes the deep seismic soundings performed in romania the technique of field works the characteristics of the recorded waves and the main results obtained on the profiles is analysed

slab in the wrong place lower lithospheric mantle delamination in the last stage of the eastern carpathian subduction retreat a model with a new type of delamination of the lower lithospheric mantle is proposed to explain the pliocene to recent tectonic evolution of the eastern carpathians we suggest that after the continental collision in middle miocene time break off of the west dipping subducting slab occurred at a depth of 70 km slab break off propagated horizontally toward the east inducing lithospheric delamination and movement of the vrancea slab into its present position delamination was followed by rapid asthenospheric rise resulting in magma generation and the explosive alkaline basaltic magmatism of the persani mountains contamination of the former subduction related magmatic reservoirs with the alkalic basaltic material and differentiation processes produced the harghita calc alkaline and shoshonitic rocks the asthenospheric rise induced crustal uplift which is the triggering mechanism for extension and formation of the brasov gheorghieni hinterland basins the extension was accommodated by shortening and folding in the foreland the vertical vrancea slab appears in our model as a segment of delaminated lower lithospheric mantle that is seismically active due to the ongoing pull of the eclogitized oceanic crust the model explains the displaced and shallow position of the slab relative to the eastern carpathian suture zone

kinematics of an arcuate fold thrust belt the southern eastern carpathians romania abstract flysch and molasse nappes of the eastern carpathians strike mainly n s and were folded and imbricated since the late early cretaceous boundaries of stratigraphic and structural units and calculated fold trend axes from the southern part of the eastern carpathians indicate a curvature of the orogen by 80 kinematic data from fault slip analysis of all nappe systems exposed in the arc document an overall nw se contraction nappes of the external moldavides nappe complex underwent deformation since the late cretaceous peaking in the miocene and exhibit fanning subhorizontal contraction axes from e w in the n striking part of the eastern carpathians through wnw ese and nw se in the northern part of the arc to nnw sse in its southwestern part geometric relations between faults and folds indicate that this fan pattern reflects an extended interval and was contemporaneous to nappe stacking and subsequent continental collision statistical analysis reveals correlation between orientation of the fanning kinematic axes and the structural trend where fanning of subhorizontal contraction axes is systematically smaller than change of strike of fold thrust structures orogen parallel extension in the tarcau nappe of the moldavides nappe complex is estimated to be 20 this low value of orogen parallel extension indicates a primary arc in contrast to bending of a previously straight fold thrust belt low orogen parallel extension and the observed pattern of structural and kinematic axes can be simulated in sand wedge indentation models where the indenter moves oblique to its margins in these models thrust traces and fold axes are curved around the arc but are parallel to the margins of the indenter away from the corner area the movement directions of the thrust faults in the models are deflected from normal to fault strike towards the movement direction of the indenter leading to fanning contraction directions similar to those observed in the eastern carpathian arc thus the main controlling factors on arc formation were the plate margin geometry i e the shape of the upper plate and the movement direction of the upper plate relative to the orientation of its margins the influence of the geometry of the continental margin in the lower plate was mainly by imposing constraints on the movement direction of the upper plate

the moho depth map of the european plate summary the european plate has a 4 5 gy long and complex tectonic history this is reflected in the present day large scale crustal structures a new digital moho depth map is compiled from more than 250 data sets of individual seismic profiles 3 d models obtained by body and surface waves receiver function results and maps of seismic and or gravity data compilations we have compiled the first digital high resolution map of the moho depth for the whole european plate extending from the mid atlantic ridge in the west to the ural mountains in the east and from the mediterranean sea in the south to the barents sea and spitsbergen in the arctic in the north in general three large domains within the european plate crust are visible the oldest archean and proterozoic crust has a thickness of 40 60 km the continental variscan and alpine crust has a thickness of 20 40 km and the youngest oceanic atlantic crust has a thickness of 10 20 km

a comparison of observed and theoretical postglacial relative sea level in atlantic canada two extreme models of late wisconsinan ice cover in atlantic canada and the northeastern u s a are shown to produce postglacial relative sea level curves that bracket existing field observations at six sites throughout the region this suggests that the true late wisconsinan ice distribution is probably intermediate to the two contrasting reconstructions proposed both ice models predict the existence of four relative sea level zones an innermost zone closest to the centre of glaciation in which relative sea level falls continuously throughout postglacial time an outermost zone in which it rises continuously and two transitional zones in which it first falls and then rises in varying proportions according to the distance from the ice margin the distinctive forms of the relative sea level curves are probably representative of each of the zones and are unlikely to be significantly perturbed even by large local ice readvances they therefore establish patterns with which future field data are expected to conform the form that the geological record of relative sea level change is likely to take within each zone is discussed and promising settings for the collection of new data are proposed the common practice of separating relative sea level into an isostatic and a eustatic component is analysed and shown to be incorrect as usually applied the practice is also shown to be unnecessary because the models discussed in this paper predict changes in relative sea level that can be compared directly with the observations

a new mixing diagnostic and gulf oil spill movement chaotic advection has served as the paradigm for mixing in fluid flows with simple time dependence its skeletal structure is based on analysis of invariant attracting and repelling manifolds in fluid flows here we develop a finite time theory for two dimensional incompressible fluid flows with arbitrary time dependence and introduce a new mixing diagnostic based on it besides stretching events around attracting and repelling manifolds this allows us to detect hyperbolic mixing zones we used the new diagnostic to forecast the spatial location and timing of oil washing ashore in plaquemines parish and grand isle louisiana and pensacola florida in may 2010 and the flow of oil toward panama city beach florida in june 2010

florida current frontal eddies and the settlement of coral reef fishes we deployed three replicate larval light traps off the upper florida keys from june september 2001 to measure the delivery of settlement stage fish larvae to the coral reefs nightly measures of larval abundance were compared to water temperatures measured across the outer reef nearby wind records and the alongshore and cross shelf components of the currents measured at the seaward edge of the reef these time series together with satellitederived sea surface temperature and color fields indicate that a very large multi taxa larval pulse on 20 july was directly associated with the passage of a florida current fc sub mesoscale frontal eddy embedded within the elongated remnant of a mesoscale eddy a second large pulse of larvae occurred when a similar mesoscale eddy passed the upper keys in mid june periods of increased tidal bore activity occurred with the passage of these eddies semidiurnal internal tides caused near bottom onshore intrusions of cooler slope waters during periods of onshore meanders of the fc front when the downstream baroclinic flow and stratification increased at the reef margin the high abundance and similarity in larval ages within taxa on 20 july indicate a keys shelf origin although the temporal and spatial scales of entrainment cannot be resolved the passage of a third mesoscale eddy in september did not result in a larval pulse possibly because of a mismatch between biological and physical criteria several of which must be met for larval transport by mesoscale eddies to be successful

cyclonic eddies in the eastern gulf of mexico abstract cold domed cyclonic eddies juxtaposed to the cyclonic shear side of the gulf loop current are observed in simultaneously obtained hydrographic current meter mooring and satellite infrared data the cyclones are initially observed in the satellite data as cold perturbations on the northern extreme of the current and grow either into a cold tongue or a quasi stable meander off the dry tortugas florida areal shipboard surveys show closed isopleths of temperature and salinity and surface geostrophic current speeds relative to 1000 db are in excess of 100 cm s 1 the diameter of the cold domes varied from 80 to 120 km separation of large anticyclonic rings is always observed to be preceded by cyclonic eddies in the transition zone between campeche bank and the west florida shelf but only on the eastern side not every cyclonic eddy off dry tortups is associated with the separation of an anticyclonic ring some are eroded away by the florida current but they have never been observed in 10 years

temporal and spatial characteristics of summer upwelling along florida s atlantic shelf abstract temperature data from shelf waters along florida s atlantic coast are used to characterize upwelling during the summer of 1980 bottom temperatures recorded at seven stations across the shelf and during 14 weekly cruises between early july and mid september show a continual cross shelf movement of the isotherms but only one primary upwelling event during the first three weeks of august upwelling ends with an exceptionally rapid warming over a one week period the largest net temperature increase of about 10 c occurs at mid and near bottom depths over the middle shelf temperature recorder data from four stations spaced along the 10 m isobath suggest that upwelling events arrive on the inner shelf along relatively restricted sections of coastline and persist between one and three weeks surface drogue data reveal an increase in current speed coinciding with lowest bottom temperatures this lends support to the likelihood that the florida current is the primary case of upwelling in florida at

crustal seismic reflection profiling in romania on the urziceni mizil line abstract this work presents the interpretation of a deep seismic reflection profile recorded in the northern extremity of the moesian platform the seismic time section and the reflectivity histogram show the presence of two distinct zones good reflectivity in the upper part for the sedimentary overburden and a continuous decrease of reflectivity with depth for the deeper part crystalline zone a correlation between the reflectivity of the crust the age of the platform and heat flow was also established the decrease in the crustal reflectivity mainly for the lower crust could be due to both a temperature decrease and higher viscosity favouring a brittle behaviour the presence of these factors could explain the lack of continuity of the reflections a crustal model based on the seismic time section is also presented and shows a thickening of the crust from south to north

characteristics of romanian lithosphere from deep seismic reflection profiling abstract the tectonic units of romania contain both alpine orogenic regions and platforms the investigations of crustal structure by near vertical reflection seismic profiling are based on less than 100 lines unequally distributed and of limited lengths 5 30 km the seismic features studied are the crustal seismic reflectivity and transparency dipping events and diffractions and the moho and subcrustal reflectivity the major common features are a reflective sedimentary cover of mostly neogene layers a weak signal from the sedimentary basement boundary a quasi transparent upper crust a mid crust with short and subhorizontal events a transparent or layered lower crust and a moho that is either poorly visible or evidenced by a zone with reflection bands and some subcrustal reflections the moesian platform together with the adjacent carpathian foredeep show a mid crust with short and subhorizontal events a crust mantle transition zone in the west an unclear or prominent moho and some subcrustal reflectivity the northern part of the carpathian foredeep shows strong seismic layering of the lower crust the central part of the transylvanian depression is characterized by short and subhorizontal events at mid crustal level a slightly reflective lower crust with diffractions and a weak moho signal the southern sector of the pannonian depression is generally marked by a reflective lower crust the tectonic significance of these seismic signatures is interpreted as follows a brittle upper crust a decoupling mid crustal zone a lower crust with brittle to ductile behaviour a possible extensional or isostatic rebalanced moho and laminated zones with reduced viscosities at the lower crust and upper mantle levels a series of crustal models based on the reflection seismic sections are presented for several areas of romania

glacioisostasy and lake level change at moosehead lake maine abstract reconstructions of glacioisostatic rebound based on relative sea level in maine and adjacent canada do not agree well with existing geophysical models in order to understand these discrepancies better we investigated the lake level history of 40 km long moosehead lake in northwestern maine glacioisostasy has affected the level of moosehead lake since deglaciation ca 12 50014c yr b p lowstand features at the southeastern end and an abandoned outlet at the northwestern end of the lake indicate that the lake basin was tilted down to the northwest toward the retreating ice sheet by 0 7 m km at 10 00014c yr b p water level then rose rapidly in the southeastern end of the lake and the northwestern outlet was abandoned indicating rapid relaxation of landscape tilt lowstand features at the northwestern end of the lake suggest that the lake basin was tilted to the southeast at ca 875014c yr b p possibly as the result of a migrating isostatic forebulge after 800014c yr b p water level at the southeastern end was again below present lake level and rose gradually thereafter we found no evidence suggesting that postglacial climate change significantly affected lake level the rebound history inferred from lake level data is consistent with previous interpretations of nearby relative sea level data which indicate a significantly steeper and faster moving ice proximal depression and ice distal forebulge than geophysical models predict

on postglacial sea level summary an exact method is presented for calculating the changes in sea level that occur when ice and water masses are rearranged on the surface of elastic and viscoelastic non rotating earth models the method is used to calculate the instantaneous elastic and delayed vi scoelastic sea level changes following the partial melting of late quaternary ice sheets we find that there can be large errors in the usual assumption that changes in sea level are uniform over the ocean basins if a quantity of ice equivalent to a uniform 100 m rise in sea level melts from the laurentide and fennoscandian ice sheets then in the south pacific the instantaneous rise in sea level can be as large as 120m in the north atlantic the instantaneous rise is always less than 100 m there is a zone in the north atlantic with almost no sea level change and near greenland and norway the sea level falls rather than rises by over 100 m one thousand years after the melting a forebulge migrating towards the ice loads causes water to flow from the south pacific into the north pacific suggesting that raised beaches should occur in the south pacific the gravitational attraction of an ice mass upon a nearby ocean tends to hold sea level high in the vicinity of the ice this extra load near the ice may have a significant influence on postglacial isostatic adjustment

the influence of loop current perturbations on the formation and evolution of tortugas eddies in the southern straits of florida large cyclonic eddies on the northern edge of the florida current are the dominant mesoscale features within the southern straits of florida the most prominent of these features is a quasi stationary eddy that forms near the dry tortugas our observations compiled from 3 years of advanced very high resolution radiometer measurements in the straits of florida and gulf of mexico demonstrate a strong relationship between the generation of anticyclonic rings from the gulf of mexico loop current and the evolution of tortugas eddies within the southern straits of florida in six cases tortugas eddies evolve from cyclonic frontal eddies which form along the boundary of the loop current the eddies remain stationary near the dry tortugas until they are impacted by an approaching loop current frontal eddy the length of time an eddy spends near the dry tortugas is increased when the loop current sheds an anticyclonic ring the involvement of a loop current frontal eddy in the ring shedding process results in a delay in its and hence the tortugas eddy s downstream propagation results suggest that the lifetime of a tortugas eddy can be as long as 140 days when a ring shedding event occurs or as short as 50 days in the absence of any ring shedding events upon entering the straits of florida the tortugas eddies are deformed by the narrowing topography and shrink to approximately 55 of their original size as they propagated downstream the shrinking of these eddies is accompanied by an accelerated translation from 5 km d in the western straits of florida to 16 km d in the east

geodynamics of the northern andes subductions and intracontinental deformation colombia new regional seismological data acquired in colombia during 1993 to 1996 and tectonic field data from the eastern cordillera ec permit a reexamination of the complex geodynamics of northwestern south america the effect of the accretion of the baudo panama oceanic arc which began 12 myr ago is highlighted in connection with mountain building in the ec the istmina and ibague faults in the south and the santa marta bucaramanga fault to the northeast limit an e se moving continental wedge progressive indentation of the wedge is absorbed along reverse faults located in the foothills of the cordilleras northward of 5 n and transpressive deformation in the santander massif crustal seismicity in colombia is accurately correlated with active faults showing neotectonic morphological evidences intermediate seismicity allows to identify a n ne trending subduction segment beneath the ec which plunges toward the e se this subduction is interpreted as a remnant of the paleo caribbean plateau pcp as suggested by geological and tomographic profiles the pcp shows a low angle subduction northward of 5 2 n and is limited southward by a major e w transpressive shear zone normal oceanic subduction of the nazca plate np ends abruptly at the southern limit of the baudo range northward the np subducts beneath the choco block overlapping the southern part of the pcp cenozoic shortening in the ec estimated from a balanced section is 120 km stress analysis of fault slip data in the ec northward of 4 n indicates an e se orientation of 1 in agreement with the pcp subduction direction northward near bucaramanga two stress solutions were observed 1 a late andean n80 e compression and 2 an early andean nw se compression

florida current meandering and evolution of cyclonic eddies along the florida keys reef tract are they interconnected 1 the florida current fc is the branch of the gulf stream system within the straits of florida connected to the loop current in the gulf of mexico cyclonic cold core eddies travel along this oceanic current system entering the straits of florida in the vicinity of the dry tortugas and evolving along the florida keys island chain and coral reefs the development of the high resolution 900 m hydrodynamic model florida straits south florida and florida keys fkeys nested within a gulf of mexico model both based on the hybrid coordinate ocean model has enabled new findings in eddy variability together with high resolution 1 km ocean color imagery multiyear model archives have been employed to study the changes in the position of the fc front and the relationship with eddy evolution it was found that eddy interactions and transformations are common with multiple eddy cells within individual eddies or new cells emerging from existing vortices features in the dry tortugas area previously thought to be semipermanent are shown to be frequently transformed and or replenished a mechanism of local cyclogenesis is also proposed incoming eddies interact with and influence the downstream propagation of previous eddies systems of eddies rather than individual vortices can form the elongated features observed between the fc front and the atlantic florida keys shelf topography plays an important role in eddy dissipation or growth a close synergy between eddy evolution and fc meandering is revealed the results have implications on the connectivity of remote coastal and reef ecosystems

the dynamics of cuba anticyclones cubans and interaction with the loop current florida current system mesoscale anticyclonic eddies along the northern cuban coast cubans have been identified in the straits of florida associated with the northward shift of the florida current fc and the anticyclonic curvature of the loop current lc at the western entrance of the straits the dynamics of cuban eddies and their interaction with the lc fc system are described for the first time using satellite drifter and buoy data and a high resolution model it is shown that the evolution of cubans to the south of the fc front complements the evolution of cyclonic eddies to the north of the fc advancing previous studies on synergy between fc meandering and eddy activity two types of cuban eddies are characterized a a main anticyclonic cell type a within the core of the lc during retracted phase conditions associated with the process of lc eddy lce shedding from an extended lc and b an individual distinct anticyclonic eddy that is released from the main lc core and is advected eastward along the northern cuban coast type b there are also mixed cases when the process of lce shedding has started so a type a cuban is being formed in the presence of one or more eastward progressing type b eddies cuban evolution is associated with an increased mixed layer and weaker stratification of the upper ocean along the eddy s track the cyclonic activity along the cuban coast and wind induced upwelling events also contribute to the evolution and fate of the cuban eddies

cyclonic eddies northeast of the campeche bank from altimetry data eight cyclonic eddies were identified near the western edge of the loop current at the northeast shelf break of the campeche bank through topex poseidon sea surface height anomaly data from january 1993 through march 2000 the eddies migration and their lifecycle are described the formation of the eddies appears to be related to the dynamics of the loop current because the timing of their generation corresponds to the last stage of the anticyclone shedding from the loop current the cyclones intensify while moving slightly to the northwest along the shelf break of the campeche bank later some cyclones are observed to move northward toward the mississippi shelf break the cyclones remain next to the campeche bank south of 268n from 1 3 to 9 6 months later some of them move northward and strengthen by merging with other eddies extending their life span the eddies vertical structure is analyzed with hydrographic data and the connection between the formation of the cyclones and the evolution of the loop current is further described using sea surface temperature images

kinematics of retreating subduction along the carpathian arc romania kinematic axes and resultant vectors of displacement along the carpathian arc and the apuseni mountains aid in the reconstruction of retreating subduction along the carpathians the recent vertical position of the subducted slab below the vrancea area of the eastern carpathians represents the final rollback stage of a small fragment of oceanic lithosphere formerly situated between the moesian and east european plates the ages and locations of the eruption centers of the andesitic volcanic chain along the carpathian arc in the overriding plate as well as the thrust directions are used as markers to reconstruct the rollback area of the subducted slab between the moesian and east european plates

interplay of tectonics and neogene post collisional magmatism in the intracarpathian region abstract distribution of the neogene calc alkaline magmatism of the carpathian arc is directly related in space and time to the kinematics of the two major terranes of the intracarpathian area alcapa tisia getia along the south eastern border of the european plate in the west carpathians and adjacent areas the volcanic activity occurred between 20 11 ma with large volumes of both acidic and intermediate rocks generally distributed randomly sometimes transversally to the orogenic belt and as rare small occurrences along the flysch belt in the east carpathians the volcanic rocks are distributed along the northern margin of the zemplin block the north easternmost part of the alcapa and eastward along the front of the getic block at the contact with european plate between tokaj slanske vihorlat up to northern calimani mountains the magmatism occurred between 14 9 ma and along the calimani harghita chain between 9 0 2 ma the calc alkaline magmatic rocks of the apuseni mountains are located in the interior of the tisia block and occurred between 14 9 ma the generation of the calc alkaline magmatism is considered here as the result of complex interplay between plate roll back and lithospheric detachment tectonic processes and the break off of the subducted plate mostly in a post collisional setting 1 the magmatites of the western carpathians and the pannonian basin were generated in direct relation to subduction roll back processes over the downgoing slab during the period of lateral extrusion and back arc extension in this area characterized by maximum crustal shortening we can infer further delamination processes to explain the generation of magmas 2 the magmatic rocks from the northern sector of the east carpathians tokaj slanske vihorlat up to the northern calimani mountains resulted after subduction roll back processes and an almost simultaneous break off of the descending plate all along the arc segment during main clockwise rotation of the intracarpathian terranes 3 in the eastern sector of the east carpathians calimani up to harghita mountains the magmatic rocks were generated through partial melting of the subducted slab followed by gradual break off of the subducted plate along strike north to south 4 the apuseni mts magmatic activity resulted in transtensional tectonic regime by decompressional melting of lithospheric mantle during the translation and rotation of tisia getia block

partial delamination of continental mantle lithosphere uplift related crust mantle decoupling volcanism and basin formation a new model for the pliocene quaternary evolution of the southern east carpathians romania abstract a geodynamic model is proposed for the mid miocene to quaternary evolution of the southern east carpathians in order to explain the relationships between shallow and deep geological phenomena that occurred synchronously during late collision tectonics in this area an active volcanic zone cross cuts since 2 my the suture between the overriding tisza dacia and subducting european continental plates mafic calc alkaline and alkaline magmas south harghita and persani volcanoes erupted contemporaneously these magmas were supplied by partial melting of the mantle lithosphere of the subducting and not of the overriding plate in an effort to decipher this geodynamically a typical setting of magma generation the spatial and temporal distribution of shallow and deep phenomena was successively examined in order to establish the degree of their interdependence our model indicates that intra mantle delamination of the subducting european plate is the principal cause of a succession of events it caused upwelling of the hot asthenosphere below a thinned continental lithosphere of the carpathians inducing the uplift of the lithosphere and its internal decoupling at the moho level by isostatic and mostly thermal effects during this uplift the crust deformed flexurally whilst the mantle deformed in a ductile way this triggered decompressional partial melting of the uppermost mantle lithosphere flexural deformation of the crust induced its fracturing allowing for the rapid ascent of magmas to the surface as well as reactivation of an older detachment horizon at the base of the carpathian nappe stack above which the brasov ciuc and gheorghieni hinterland basins formed by extension and gravity spreading the rapid subsidence of the focsani foreland basin is controlled by the load exerted on the lithosphere by the delaminated mantle slab that is still attached to it in this model crust mantle decoupling magma genesis and volcanism local near surface hinterland extension are consequences of uplift induced by asthenospheric upwelling triggered by intra mantle delamination this model enables to conceive that delamination induced decoupling began to be efficient 9 4 my ago at the northern end of the east carpathians when the mantle slab dipped westwards since then intra mantle delamination migrated laterally normal to the slab strike and follows the arcuate shape nw se sw of the carpathians nowadays whereas the mantle slab is still actively foundering below the vrancea seismic zone to the se of the most recent volcanic area south harghita persani a significant southwestward shift of the delamination process can be discerned

models for relative motion of crustal blocks within the carpathian region based on restorations of the outer carpathian thrust sheets details of the oligocene present day motion of the adriatic block with respect to europe can be determined by palinspastic restorations of the outer carpathians thrust sheets the arcuate nature of the carpathians poses problems for simple restorations of sections because they create converging restoration paths which require large amounts of strike parallel extension 40 50 such large amounts of extension are not seen on maps or in the field a combination of thrust transport directions changing with time between and within thrust sheets and divergent transport directions helps minimise the arc parallel extension necessary 18 25 the pannonian basin can be treated either as an area dominated by strike slip motion rigid block movements or as an area of back arc extension the differences in restoration geometry produced by these two scenarios help to indicate which of the two mechanisms was dominant the consequences of the rigid block restoration indicate the model is inappropriate because it requires approximately 20 clockwise rotation of the adriatic block during the late tertiary it also indicates at least 300 km strike slip motion distributed among the late tertiary faults of the dinaride balkanide and hellenide mountain belts the back arc extension model alleviates the the 20 clockwise rotation of the adriatic block and requires about 200 km distributed strike slip motion in yugoslavia and bulgaria

macrofossil record of a middle holocene drop in relative sea level at the st lawrence estuary quebec abstract macrofossil analysis of a peat layer overlying shallow water estuarine sediments allows the reconstruction of vegetation changes between 7000 and 6000 14c yr b p near montmagny quebec about 7500 7000 14c yr b p the study site was brackish and intertidal next a cattail marsh dominated by typha changed into a terrestrial fire prone environment that contained xero mesophilous tree species pinus tsuga and lasted a few hundred years until about 6800 14c yr b p this rapid change may have resulted from land tilting associated with the northward migration of the postglacial forebulge an abrupt change from a pinus tsuga dominated cover to shrubby vegetation was due to a fire that affected the site 6800 14c yr b p fossil mosses at the site reflect local wetness likely produced by a rise in the water table starting about 6600 14c yr b p by 6500 6400 14c yr b p seawater returned and freshwater plants were replaced by semihalophilous and halophilous plants thinning of annual rings in fossil larch reflects this change from a terrestrial peatland to a treeless coast

strange bedfellows a deep water hermatypic coral reef superimposed on a drowned barrier island southern pulley ridge sw florida platform margin abstract the southeastern component of a subtle ridge feature extending over 200 km along the western ramped margin of the south florida platform known as pulley ridge is composed largely of a non reefal coastal marine deposit modern biostromal reef growth caps southern pulley ridge spr making it the deepest hermatypic reef known in american waters subsurface ridge strata are layered lithified and display a barrier island geomorphology the deep water reef community is dominated by platy scleractinian corals leafy green algae and coralline algae up to 60 live coral cover is observed in 60 75 m of water although only 1 2 of surface light is available to the reef community vertical reef accumulation is thin and did not accompany initial ridge submergence during the most recent sea level rise the delayed onset of reef growth likely resulted from several factors influencing gulf waters during early stages of the last deglaciation 14 kyr b p including cold low salinity waters derived from discrete meltwater pulses high frequency sea level fluctuations and the absence of modern oceanic circulation patterns currently reef growth is supported by the loop current the prevailing western boundary current that impinges upon the southwest florida platform providing warm clear low nutrient waters to spr the rare discovery of a preserved non reefal lowstand shoreline capped by rich hermatypic deep reef growth on a tectonically stable continental shelf is significant for both accurate identification of late quaternary sea level position and in better constraining controls on the depth limits of hermatypic reefs and their capacity for adaptation to extremely low light levels

on the decay of a baroclinic jet flowing along a continental slope a jet flowing in the kelvin wave propagation direction along the seaward side of a continental slope is found to decrease in strength as it leaks mass onto the continental shelf as a result a shelf break jet flowing in the opposite direction is induced on the shelf the combination of these two flows creates a decaying high pressure tongue centered about the shelf break an idealized reduced gravity model is developed to examine the two flow combination in the model a baroclinic open ocean jet flows next to a continental shelf over which the flow is barotropic and dominated by a linear bottom friction proportional to along shelf velocity the far field depth of the thermocline is assumed to be much greater than the depth of the shelf break a solution is found in the limit of small cross slope flow the mathematical problem of finding the flow on the shelf is equivalent to that of heat conduction on a semi infinite rod with a finite heat source placed at the end of the rod a numerical shelf slope junction model is devised to allow the requirement of small cross slope flow to be relaxed the numerical model which incorporates higher order dynamics confirms the qualitative results obtained from the analytic model the motivation for the development of the theory lies in observational evidence of a northward flowing jet along the continental slope off the west florida shelf apparently stemming from the loop current the structure of the flow combination over the shelf break is confirmed with historical hydrographic data and advanced very high resolution radiometer imagery

tomographic imaging of deep velocity structure beneath the eastern and southern carpathians romania implications for continental collision the vrancea seismic zone located beneath the elbow of the eastern and southern carpathians is characterized by intermediate depth seismicity associated with subduction and plate collision among many strong earthquakes that have occurred in the region the 1977 vrancea earthquake march 4 1977 ms 7 1 depth of 86 km caused extensive damage and fatalities the vrancea seismic zone is defined by a tabular region of seismicity that extends from the surface to a depth of 200 km the small size about 80 km in length and 40 km in width and geometry of the seismic zone have made it difficult to interpret the kinematics of subduction and continental collision in the romanian carpathians to better understand the collision subduction environment body wave seismic tomography was used to image the deep structure beneath the eastern and southern carpathians in romania a total of 7837 p and 2292 s arrival times from 433 shallow and intermediate depth earthquakes recorded by local and regional seismic stations were inverted for the three dimensional 3 d seismic velocity structure the travel times and ray paths were calculated by an efficient 3 d ray tracing technique by utilizing the lsqr algorithm p and s wave velocity perturbations were determined from the surface down to a depth of 200 km the high resolution p wave tomographic images reveal a pattern of broad heterogeneity in the velocity structure of the region one of the most important features is a high velocity body existing beneath the carpathian arc at depths between 100 and 170 km this high velocity body outlines a slab dipping near vertically where most of the intermediate depth earthquakes occur beneath the transylvanian basin a high velocity zone is dipping toward the se and may represent the base of lithosphere which is in convergence with the subducted slab low velocity bodies are found along the forearc of the carpathian foredeep down to depths of 70 to 80 km these low velocity bodies may be correlated with the shallow sedimentary layer in the foreland and may represent crustal materials wedged and underthrust along with the subducted lithosphere