late pleistocene and holocene depositional systems and the palaeogeography of the dogger bank north sea 3d seismic data from the dogger bank north sea allow the mapping of late pleistocene and holocene depositional systems in unprecedented detail the data demonstrate that glacial processes resulted in the development of incised tunnel valley systems during the weichselian and that these were subsequently modified by fluvial processes in a pro glacial setting subsequently the dogger bank formed an emergent plain during the holocene with a complex meandering river system associated tributary or distributary channels and lakes dominating the region prior to the sea level rising sufficiently to submerge the dogger bank around 7500 yr ago the meandering river system was replaced by a dendritic channel network of potential fluvial estuarine or intertidal origin as the holocene depositional features bear no systematic relationship to the bathymetry this study demonstrates that previously published bathymetry based models for the holocene palaeogeographic development of the north sea require modification

genesis and evolution of a mid shelf storm built sand ridge new jersey continental shelf u s a abstract sand ridges form discrete parts of a modern surficial veneer on many continental shelves worldwide yet are seldom cited as analogs for isolated marine sand bodies found in outcrop or the subsurface one reason may be that a comprehensive explanation for the evolution of modern mid shelf sand ridges has proven elusive new information most notably high resolution seismic data collected on modern sand ridges in adjacent areas by other workers has led to this reevaluation of a largely unpublished but extensive vibracore dataset from a mid shelf sand ridge off new jersey usa the presence of dipping reflections within other ridges is particularly notable on new high resolution seismic data but has yet to be confirmed in these other ridges by extensive coring reexamining the original well preserved vibracore peels from the mid shelf sand ridge sampled in the 1980s reveals that these internal reflections could be associated with burrowed low density mud beds new cross sections constructed with 20 vibracores suggest that the dipping internal reflections are accretionary surfaces associated with episodic ridge migration to the east and south radiocarbon dating indicates that the mid shelf sand ridge has migrated episodically over the last 5 ka and movement probably continues today during major storms this documented migration continues well after transgressive ravinement approximately 9 10 ka contradicting existing views that mid shelf ridges become moribund sometime after detachment from the shoreline the morphology migration history and internal sedimentary character suggest that the ridges are acting much like primary bedforms although these sand bodies are much larger in scale 5 to 8 m height or thickness than typical subaqueous dunes observed on modern storm dominated shelves

methodology for dense spatial sampling of multicomponent recording of converted waves in shallow marine environments a widespread use of converted waves for shallow marine applications is hampered by spatial aliasing and field efficiency their short wavelengths require dense spatial sampling which often needs to be achieved by receivers deployed on the seabed we adopted a new methodology where the dense spatial sampling is achieved in the common receiver domain by reducing the shot spacing this is done by shooting one track multiple times and merging the shot lines in an effective manner in a separate processing step this processing step is essential because positioning errors introduced during the field measurement can become significant in the combined line particularly when they exceed the distance between two adjacent shot positions for this processing step a particular shot line is used as a reference line and relative variations in source and receiver positions in the other shot lines are corrected for using crosscorrelation the combined shot line can subsequently be regularized for further processing the methodology is adopted in a field experiment conducted in the danube river in hungary the aim of the seismic experiment was to acquire properly sampled converted wave data using a multicomponent receiver array the dense spatial sampling was achieved by sailing one track 14 times after correcting for the underwater receiver positions using the direct arrival the crosscorrelation step was applied to merge the different shot lines the successfully combined result is regularized into a densely sampled data set free of visible spatial aliasing and suitable for converted wave processing

interpolation of an intertidal digital elevation model from heighted shorelines a case study in the western wash abstract a method of interpolating a spatiotemporal digital elevation model dem of an intertidal zone from a set of heighted shorelines is described the heighted shorelines are obtained by the water line method using remote sensing and hydrodynamic modelling this enables an intertidal dem to be constructed over a large area relatively quickly as well as frequent subsequent updating of the dem to detect changes the dem may be used for studying sediment transport in the intertidal zone and for the development of improved hydrodynamic models the spatiotemporal interpolator is based on universal block kriging and its results are illustrated using data from the wrangle flats area of the western wash u k for a kriging block size of 50 m 50 m 1100 days an average block height estimation standard deviation of 14 3 cm is achieved using shorelines from 33 images collected over the period 1992 1994 this height accuracy is compared with those obtained from dems constructed from beach transect data and is shown to be an improvement over the transect dem accuracies away from transects the construction of dems of improved accuracy 13 cm from combined shoreline and beach transect data using cokriging is discussed ways in which the shoreline accuracies may be improved are also considered

alpha and beta diversity of encrusting foraminifera that recruit to long term experiments along a carbonate platform to slope gradient paleoecological and paleoenvironmental implications abstract the spatial and temporal distribution and diversity of sediment dwelling foraminifera are reasonably well known but encrusting hard substrate dwelling foraminifera are little studied encrusting foraminifera are common in the world s oceans attached to floating debris or marine animals in the water column to living on rocks sand grains and organisms in benthic environments from shallow to deep marine regions with projected ocean acidification and warming conditions these important calcifying protists that comprise beaches buffer sediments and contribute to complex food webs are potentially in peril results indicate that calcifying foraminifera were the first to colonize experimental molluscan substrates within the first year in shallow habitats with colonization offshore in subsequent years agglutinated foraminifera become more common after one year species richness diversity remained relatively similar throughout the study but species turnover diversity was greatest within the first year and between the shelf slope break and deeper water following the thermocline and photic zone regions the equivalent of the shannon entropy index provided important information on diversity and community structure paleobathymetric distributions can be resolved after six years into four distinct foraminiferal distributional zones shallow shelf 15 m outer shelf 33 m shelf slope break 73 88 m and slope depths 213 m to 267 m some encrusting foraminifera are invasive settling in high numbers within the first year and increasing their abundance through the duration of the experiment a foraminiferan discorbis bertheloti was discovered to bioerode carbonate and is a potentially excellent paleobathymetric indicator for 15 33 m depths results differ from previously reported pioneer and climax foraminiferal communities documented for caribbean coral reefs because long term experiments reveal the spatial and temporal development and distribution of carbonate producing encrusting foraminifera in these climatically sensitive regions

shallowly buried enigmatic seismic stratigraphy on the new jersey outer shelf evidence for latest pleistocene catastrophic erosion chirp seismic profiles reveal a prominent seismic facies boundary 0 20 m below the seafloor within an 8 6 10 2 km area of the new jersey outer shelf this irregular boundary separates seismically transparent facies from underlying stratified facies the irregularities form two populations of incisions trending northeast and east northeast stratified blocks within the transparent facies occasionally within presumed incisions together with lithologic evidence indicate that some of the transparent facies was formed by disruption of the stratified facies preservation of steep 50 90 incision flanks implies that deposition of the transparent facies closely followed disruption catastrophic erosion and redeposition following the multiple breaching of glacial lake dams to the north ca 19 12 ka constitute the likeliest mechanisms both for producing facies boundary incisions and emplacing the transparent facies implying that local forcing can generate erosional unconformities on periglacial shelves in the absence of base level change this facies boundary adds complexity to the already complex shallowly buried stratigraphic record of the last glacio eustatic cycle on the new jersey continental shelf long considered typical of periglacial shelves worldwide

tracking the last sea level cycle seafloor morphology and shallow stratigraphy of the latest quaternary new jersey middle continental shelf seafloor geomorphology and surficial stratigraphy of the new jersey middle continental shelf provide a detailed record of sea level change during the last advance and retreat of the laurentide ice sheet 120 kyr b p to present a nw se oriented corridor on the middle shelf between water depths of 40 m the mid shelf paleo shore and 100 m the franklin paleo shore encompasses 500 line km of 2d huntec boomer profiles 500 3500 hz an embedded 4 6 km2 3d volume and a 490 km2 swath bathymetry map we use these data to develop a relative stratigraphy core samples from published studies also provide some chronological and sedimentological constraints on the upper 5 m of the stratigraphic succession the following stratigraphic units and surfaces occur from bottom to top 1 r a high amplitude reflection that separates sediment 46 5 kyr old by ams 14c dating from overlying sediment wedges 2 the outer shelf wedge a marine unit up to 50 m thick that onlaps r 3 channels a reflection sub parallel to the seafloor that incises r and appears as a dendritic system of channels in map view 4 channels fill the upper portion of which is sampled and known to represent deepening upward marine sediments 12 3 kyr in age 5 the t horizon a seismically discontinuous surface that caps channels fill 6 oblique ridge deposits coarse grained shelly units comprised of km scale shallow shelf bedforms and 7 ribbon floored swales bathymetric depressions parallel to modern shelf currents that truncate the oblique ridges and cut into surficial deposits we interpret this succession of features in light of a global eustatic sea level curve and the consequent migration of the coastline across the middle shelf during the last 120 kyr the morphology of the new jersey middle shelf shows a discrete sequence of stratigraphic elements and reflects the pulsed episodicity of the last sea level cycle r is a complicated marine non marine erosional surface formed during the last regression while the outer shelf wedge represents a shelf wedge emplaced during a minor glacial retreat before maximum wisconsin lowstand i e marine oxygen isotope stage 3 1 channels is a widespread fluvial subarial erosion surface formed at the late wisconsin glacial maximum 22 kyr b p the shoreline migrated back across the mid shelf corridor non uniformly during the period represented by channels fill oblique ridges are relict features on the new jersey middle shelf while the ribbon floored swales represent modern shelf erosion there is no systematic relationship between modern seafloor morphology and the very shallowly buried stratigraphic succession

stratigraphic variability due to uncertainty in model boundary conditions a case study of the new jersey shelf over the last 40 000 years abstract prediction of stratigraphy by numerical sedimentary models is influenced by a series of geological boundary conditions paleo bathymetry sediment supply sea level ocean storm climate and tectonics these boundary conditions evolve non linearly over time and have considerable uncertainty this study explores the impact of the uncertainty of complex boundary conditions on stratigraphic prediction two numerical models are sequentially run the climate driven hydrological model hydrotrend generates a time series of discharge and sediment load at the river mouth which then feed into the process based stratigraphic model sedflux 2d sedflux disperses sediment in the fluvio marine domain the bedload fluxes drive floodplain and mouthbar deposition while suspended sediment is dispersed in the ocean through hypopycnal plumes seafloor sediment is reworked by ocean storms failures and subsequent transport as sediment gravity flows sedflux records the thickness of the deposited sediment and the grain size preserved over time along a longitudinal profile one base case simulation and 20 sensitivity tests of the new jersey shallow margin over the last 40 000 yr serve to explore the impact of uncertain boundary conditions initially the shelf is exposed and arctic conditions prevail in the drainage area paleo temperature and precipitation estimates differ significantly between different community climate system model realizations impacting river sediment flux predictions subsequently high sediment supply from the rivers draining the melting laurentide ice sheet has a dominant impact on the shelf stratigraphy drainage basin characteristics are strongly controlled by the hard to define details of the laurentide ice sheet dynamics over the last 10 000 yr the shelf becomes sediment starved and storm dominated but the paleo storm conditions are uncertain and thus require a wide range of values shallow seismic data have been used to validate the large scale deposited thicknesses of the sedflux prediction the base case sedflux prediction for the sedimentary architecture of the new jersey shelf is consistent with the acoustically observed distribution of major sediment wedges due to the strong forcing of the relatively well constrained sea level changes the range in thickness predictions over the sensitivity tests is well within the lateral variations reconstructed from the observed seismic data sedflux predictions and a data set of 654 seafloor samples taken on the new jersey shelf between 50 and 150 m water depth shows a subtle fining towards deeper water sedflux systematically overpredicts the component of fine sediments at the seafloor likely because the model does not predict shell hash paleo storm climate is found to have a high uncertainty and strongly impacts the predicted grain size distributions we advocate a modeling approach which couples a series of sensitivity experiments to a predicted base case experiment in that way the stratigraphic variability caused by uncertainty in the boundary conditions is evident for later users

morphological patterns of southeastern mediterranean river mouths the topographic setting of the beach as a forcing factor abstract israeli mediterranean river mouths are characterized by an extremely dynamic morphology as their channels tend to migrate hundreds of meters north and south along the shoreline this study aims to characterize the impact of the topographic setting of the beach on the dynamic morphology of seven of these river mouths this was achieved by morphologically mapping and monitoring the natural channel dynamics of each mouth over time recognizing their spatial and temporal migration and avulsion patterns describing generalizing and classifying the different types of river mouths present on the coast and investigating the influence of the adjacent topography on their morphology detailed geomorphologic mapping was achieved using remote sensing and gis techniques utilizing more than 300 aerial photographs taken between 1918 and 2005 this study revealed a number of typical differences in these patterns attributed to differences in the topographic setting of the beach in the vicinity of the mouths elongated strip topography coasts demonstrate a uniform slope beach with equally spaced elevation contours forming a narrow sandy strip between the shoreline and the back berm funnel topography coasts exhibit a non uniform slope with a funnel shaped topographic depression adjacent to the river mouth similarities were found between the spatial and the temporal morphological patterns of river mouths flowing in each of these two topographical settings elongated strip mouths are deflected alongshore a barrier and demonstrate high migration distances and little temporal change the morphology of funnel mouths was found to be highly temporally variable yet less spatially dynamic as these mouths channels are restricted by their funnel topography this study concludes that the topographic setting of the beach a constant element in the temporal scale of this study is a primary factor influencing the morphology of the studied mouths

seismic and bathymetric evidence for four different episodes of iceberg scouring on the new jersey outer shelf possible correlation to heinrich events abstract re analysis of dense chirp seismic surveys on the outer new jersey shelf reveals two sets of shallowly buried incisions the incisions are linear to slightly sinuous oriented ne sw and exhibit cross cutting relationships we interpret both sets as paleo iceberg scours one set cuts into the r horizon a regional unconformity that formed 45 40 ka and which was subsequently buried by the finer grained outer shelf sediment wedge osw the second set is part of an erose boundary between a layered lower unit of the osw and an upper more transparent unit the erose boundary scours are deeper and have steeper slopes than the r horizon scours the latter often exhibit bermed edges whereas the former do not these differences in cross sectional morphology are likely determined by the material properties of the sediments being scoured sand at the r horizon and clay at the erose boundary the orientation of both sets of scours is consistent with previously recognized iceberg scours in stratigraphically younger seafloor on the outer new jersey shelf in 110 150 m water depths located 40 km to the northeast we argue that heinrich events recurring periods of massive iceberg flux into the north atlantic represent the most likely times for transporting icebergs to these latitudes based on stratigraphic relationships a recently published ambient sea level curve and radiocarbon age constraints we attribute the r horizon scours to heinrich event h4 37 cal ka the erose boundary scours to h3 30 cal ka and the seafloor scours to h2 23 cal ka and or h1 17 cal ka facies changes immediately following the r horizon and erose boundary scours may be related to heinrich event forced climate changes perhaps the onset of interstadial conditions and associated melt water pulses floods these pulses floods repeatedly carried fine grained rock flour produced by widespread glacial erosion to the new jersey shelf

high resolution seismic imaging of outcrop scale channels and an incised valley system within the fluvial dominated lower freshwater molasse aquitanian western swiss molasse basin abstract high resolution seismic reflection surveys on lake geneva near lausanne switzerland allow the interpretation of outcrop scale sedimentary features within the fluvial dominated lower miocene lower freshwater molasse bedrock seismic modelling of an outcrop is used to calibrate the seismic data and assist with interpretation seismic resolution is sufficient to image sandstone channel fill complexes 4 5 m thick five seismic facies are recognized and interpreted as fluvial architectural elements of the lower freshwater molasse two of these facies are characterized by fairly continuous reflections of variable frequency and low to moderate amplitude interpreted as metre thick channel fill complexes the lateral extent of such channels ranges from 100 to 170 m the other three seismic facies are characterized by moderate to high amplitude sub parallel continuous reflections the three facies are mainly distinguished using reflection frequency and continuity they correspond to distinct floodplain settings i e proximal intermediate and distal with respect to the active channel belt on a larger scale a portion of a ca 50 m deep incised valley system probably caused by a relative base level fall was identified two distinct valley fill units are recognized the lower unit was interpreted as comprising valley edge slump units by comparison with outcrop data the upper unit is interpreted as the fluvial fill deposited in the most landward portion of the valley

automatic extraction of shorelines from landsat tm and etm multi temporal images with subpixel precision abstract a high precision geometric method for automated shoreline detection from landsat tm and etm imagery is presented the methodology is based on the application of an algorithm that ensures accurate image geometric registration and the use of a new algorithm for sub pixel shoreline extraction both at the sub pixel level the analysis of the initial errors shows the influence that differences in reflectance of land cover types have over shoreline detection allowing us to create a model to substantially reduce these errors three correction models were defined according to the type of gain used in the acquisition of the original landsat images error assessment tests were applied on three artificially stabilised coastal segments that have a constant and well defined land water boundary a testing set of 45 images 28 tm 10 etm high gain and 7 etm low gain was used the mean error obtained in shoreline location ranges from 1 22 to 1 63 m and the rmse from 4 69 to 5 47 m since the errors follow a normal distribution then the maximum error at a given probability can be estimated the results confirm that the use of landsat imagery for detection of instantaneous coastlines yields accuracy comparable to high resolution techniques showing the potential of landsat tm and etm images in those applications where the instantaneous lines are a good geomorphological descriptor

man s influence on the erosion and transport of sediment by asian rivers the yellow river huanghe example during the holocene sediment input from the yellow river to the yellow sea and adjacent areas has amounted to about 3000 km 3 detailed records from river gauging stations over the past 70 yrs together with estimates based on earlier historic records suggest that the river has contributed 2300 km 3 of sediment during the last 2300 yrs an average discharge of 1 km 3 yr 1 x 10 9 t yr prior to extensive agricultural use of the loess plateau in northern china beginning about 200 bc therefore the river s load must have been about 0 1 km 3 yr an order of magnitude lower than that at present a broad delta 20 m below sea level suggests that early holocene rates were higher than the pre agricultural average and therefore that middle holocene loads were low

sediment transport in the new york bight north american atlantic shelf vincent c e swift d j p and hillard b 1981 sediment transport in the new york bight north american atlantic shelf mar geol 42 369 398 aanderaa current meter data collected during the course of noaa s new york bight project are sufficiently extensive in time 135000 observation hours and space 41 stations to permit an estimate of the sediment transport in this area the analysis is based on mean flow observations the role of wave oscillatory currents in resuspending sediment is considered but not explicitly included in the sediment transport calculations an estimate of the potential sediment transport rate qb at each station for three different threshold velocities uth 12 16 and 20 cm s 1 were made using a bagnoldtype transport equation qb const uc uth 3 for uc uth qb 0 for uc uth where uc is the mean current speed comparison was made between the results from this simple equation and other bedload and suspended load transport rates which include wave data for a limited subset of the bight data this comparison indicates that the bagnold results are reasonable for the along isobath transport estimates but are not reliable for the cross isobath transport in the cross isobath direction waves appear to play a dominant role in determining the transport rate the comparison also indicates that the bagnold approach tends to overestimate transport in deep water in shallow water resuspension of sand and rotor pumping of current meters both may become important and sediment transport calculations may not be accurate fine sediment suspended transport is approximately double the potential bedload transport for fine sand 0 02 cm but does not dominate the total transport as is believed to occur on the washington shelf smith and hopkins 1972 the data show that the new york bight is a storm dominated shelf with the general southwestward drift of water 6 cm s 1 modulated by more intense storm induced flows the transport calculations indicate that the bulk of sediment transport occurs during the winter months when wind stress is at a maximum and the water column is well mixed two major transport provinces are present a the hudson shelf valley and b the rest of the shelf the shelf valley acts as a sink and a barrier to the continuity of the mainly southwestward transport of sediment 104 g cm 1 yr 1 along the shelf within the valley the potential transport of material is of the order of l05 g cm 1 yr 1 along the valley axis progressive vector transport paths for fine sediment indicate that removal of sediment out of the ends of the valley can occur rapidly however consider ation of the finesediment budget for the whole hudson shelf valley and of the attenua tion of wave activity with depth show that these results are not inconsistent with the presence of high mud concentrations in the valley up valley sediment rates predominate during the period for which data are available

using csem techniques to map the shallow section of seafloor from the coastline to the edges of the continental slope many important processes occur within the shallow section of the seafloor on the continental shelf and slope yet conventional geophysical constraints on the physical properties within this critical boundary layer are limited some of the key constraints involve quantification of fluids within the seafloor which can be provided by electrical methods this paper reviews the application of a towed em system to map the uppermost 20 m of seafloor in a variety of settings ranging from nearshore regions in water depths of approximately 10 m on the continental shelf out to water depths of 1300 m the system is a mapping tool that provides areal maps of seafloor resistivity and has been used for a variety of purposes including sedimentary characterization and facies mapping evaluation of groundwater discharge and mapping seafloor mounds in the gulf of mexico thought to contain massive deposits of gas hydrate

evaluation of annual mean shoreline position deduced from landsat imagery as a mid term coastal evolution indicator abstract the shoreline is a useful indicator of mid term coastal evolution every shoreline is affected by instantaneous sea level the length of the run up and beach profile changes in this work annual mean shorelines are evaluated in a manner that avoids these effects by averaging the instantaneous shoreline positions registered during the same year a set of 270 shorelines obtained from landsat imagery between 2000 and 2014 using the method described in pardo pascual et al 2012 have been used it has been shown that the use of annual mean shorelines enables the same rate of change to be obtained as when using all the shorelines but that the data is simpler to manage and more useful when visualising local changes it has also been shown that annual mean shorelines largely remove the short term variability and are therefore useful for analysing mid term trend quantifications in addition we propose a methodology for annual mean shorelines obtained from landsat imagery that minimises the effects of sea level variation on the shoreline positions both shorelines instantaneous and mean annual appear to be about 4 or 5 m seaward from those obtained using more precise sources

high resolution 3d seismic reflection and coring techniques applied to late quaternary deposits on the new jersey shelf studies of variable small scale features typical of quaternary glacimarine environments require an interdisciplinary approach precisely navigated high resolution 3d seismic surveys nested within a regional 2d seismic framework and integrated with a precisely navigated coring program designed to sample specific shallow acoustic facies we illustrate this approach with examples from continuing studies of sediments on the new jersey continental shelf surficial stratigraphy associated with the latest pleistocene holocene deglaciation has been imaged twice in true 3d using the huntec dts system a deep towed high frequency 500 3500 hz boomer source in both cases nominal profile spacing was 10 m 2 5 m shot points penetration of 40 ms 30 m was achieved seismic facies in the upper 5 m have been interpreted using differential gps navigated vibra cores accuracy of position of both seismic profiles and core locations approaches 5 m much smaller than the wavelengths of the geologic features being imaged sampled survey results show multiple sediment filled channels buried beneath the modern outer shelf meandering south and southeast in the general direction of the shelf edge channels are typically a few meters deep and 100 200 m across lateral continuity between the channeled surfaces within the outer shelf wedge and the mid shelf cannot be demonstrated because of later erosion but both sets of channels incise reflector r believed to be a pre late wisconsinan exposure surface ams14c dates on benthic foraminifers from cores show that channels on the midshelf are cut into sediment 45 000 yrs old and filled with muddy sediment as young as 12 500 yrs whereas channels on the outer shelf are filled with coarser and perhaps older sediment both sets of filled channels are buried beneath a surficial sand layer the integrated approach described here can remove some uncertainties and considerably sharpen the quaternary stratigraphic picture without the perspective obtained from 3d seismic surveys and equally precise sampling interpretations based on broader regional seismic surveys and spot coring are inevitably constrained by the potential for mismatching shallow acoustic and sedimentary facies

removal of diurnal tidal effects from an ultra high resolution 3 d marine seismic survey on the continental shelf offshore new jersey an ultra high resolution 3 d single channel seismic survey was performed off the coast of new jersey in 1993 to study the late quaternary history of sedimentation on the northwest atlantic continental margin see davies et al 1992 as a part of the office of naval research strataform initiative nittrouer and kravitz 1995 three different sets of profiles were acquired figure 1 but only the set with highest spatial density is discussed here a single ten element receiver recorded 300 ms of data for every shot during the survey which covers a total area of 0 6 km north south 7 75 km east west see table 1 the deep towed huntec source deployed at 30 m depth produced frequencies of 500 to 3500 hz a band pass filter with corner frequencies at 1000 and 3500 hz was applied during preprocessing

shock wave equation of state of enstatite shock compression data are reported for hot pressed bamble bronzite en 86 loaded to pressures between 104 and 161 gpa when compared to earlier shock wave data on en 90 at lower pressures and to static compression data our data require the presence of a phase change in p space the data yield two distinct trajectories which cannot be explained by experimental error the higher density data corrected for porosity and a small amount of metallic iron impurity agree with a theoretical en 86 high pressure phase hugoniot calculated from static compression equation of state data for perovskite pv structure silicates when experimental errors and uncertainties in the equation of state parameters are considered all the en86 data can be described by a calculated hugoniot if the first pressure derivative of the mgsio 3 pv bulk modulus is taken as 4 5 1 0 combining the present preferred data with recent shock wave data for single crystal forsterite we find that en 86 is slightly more dense than fo86 at pressures above 110 gpa comparison of the forsterite and enstatite data with the preliminary reference earth model prem lower mantle densities with corrections applied for the higher shock temperatures relative to lower mantle temperatures shows that prem densities are satisfied by olivine or pyroxene stoichiometries with mg mole fractions from 0 82 to 0 90 these values are lower than estimates of 0 90 to 0 95 developed from extrapolating static compression data to lower mantle conditions

strataform overview of its design and synthesis of its results abstract the strata formed on continental margins record the history of both marine and terrestrial events occurring on earth the strataform program was created to develop a better understanding of relationships between these events and margin stratigraphy in order to obtain the maximum information from strata they are being examined simultaneously on various temporal and spatial scales and their formation is being studied where events and accumulation are known to be active the general objectives of strataform are to add geological perspective to studies of sedimentary processes to constrain stratigraphic interpretations better and to develop numerical models relating processes and stratigraphy this research is being undertaken on margins off northern california and new jersey which provide unique opportunities for investigation of short term and long term stratigraphy respectively this volume and paper focus upon studies undertaken off northern california north of cape mendocino this area is tectonically active with a coastal mountain range narrow shelf and input of sediment primarily from the eel river recent estimates indicate that 1 to 3 10 7 t yr of mud silt and clay are supplied to the continental shelf sand accumulates on the inner shelf 70 reaches the continental slope or deeper during the previous lowstand of sea level sediment discharge was 25 greater and probably led to hyperpycnal debris and other flows transporting sediment down the slope on the eel shelf flood and storm events combine to create normally stratified fine grained layers with basal sand and much terrestrial organic debris these layers are modified through time but some can be buried and preserved subsurface flood layers seem to impact observations of acoustic backscatter on the middle shelf and subsurface fluids gas freshwater affect electromagnetic measurements on the inner shelf budgets of eel river mud accumulation for the past century indicate 20 trapped on the adjacent shelf and 20 on the upper slope 150 600 m the remaining 60 is dispersed to more distal locations over holocene time scales eel river sediment has built a small sandy subaqueous delta and a subtle bulge of muddy sediment on the middle shelf north of the river gullies have been eroded on the open slope during lowstands of sea level and have accreted upward during highstands a massive failure has formed the humboldt slide due to earthquake activity and unstable substrates possibly from excess pore pressures and gas the tectonic setting has impacted margin stratigraphy from small scales fluid expulsion pockmarks to large scales spatial variation of late cenozoic sedimentation the broad dispersal of eel sediment demonstrates the three dimensional character of the resulting stratigraphy including the large scale clinoform structure developed on the shelf upper slope the rollover point topset foreset boundary for this feature is the shelf break i e below sea level which is important information for stratigraphic interpretations of sea level change

sequence stratigraphy of the burdigalian rudeis formation in ras el ush oil field gulf of suez application of gamma ray analysis and biostratigraphy abstract the rudeis formation represents one of the most important oil producing reservoirs in the gulf of suez this formation exhibits conspicuous lateral facies changes and therefore presents a complex exploration target due to tectonic activity in the study area it is composed largely of shale with a few limestone interbeds but so far composed of fine grained marl and sandstone here we interpret the sequence stratigraphy of the rudeis formation at two onshore wells ras el ush 7 and ras el ush 8 in the southernmost western shore of the gulf of suez via the integration of gamma ray log and biostratigraphic data in order to develop a high resolution sequence stratigraphic model of these syn rift rocks and determine their viability for hydrocarbon exploration using new biostratigraphic analysis of calcareous nannoplankton and planktic foraminifera we verified the ages of the rudeis successions our results suggest the occurrence of three burdigalian depositional sequences sq1 sq2 and sq3 along with six stratigraphic surfaces delineating sedimentation cycles and were mainly deposited in inner shelf to upper slope settings each of the sequences typically contains a transgressive systems tract bounded above by a maximum flooding surface and a highstand systems tract bounded above by a sequence boundary we further demonstrate that the variable timing in deposition and erosion of these depositional sequences were controlled by either local tectonism associated with gulf of suez rifting or eustatic sea level changes

shoreline changes along the rosetta nile promontory monitoring with satellite observations abstract a study to test the effectiveness of satellite data for monitoring shoreline change is reported the rapidly changing rosetta promontory of the nile delta egypt being selected as the study area landsat multispectral scanner mss image data in the near infrared 0 8 1 1 m 80 m resolution covering a 15 year period 1972 1987 at roughly 3 year intervals were compiled these were digitally overlain registered and differenced relative to the initial 1972 shoreline and composite changes erosion and accretion are mapped the area studied is one undergoing both aggradation and degradation depending on location sediment supply and man made barriers it was found that the general trend of the regional processes can be monitored with landsat imagery due to its repetitive coverage and good spectral contrast of land and sea improved satellite imagery with higher resolution should be a valuable tool for complementing traditional shoreline monitoring surveys in easily eroded lowlying areas such as the nile delta

high resolution swath sonar investigation of sand ridge dune and ribbon morphology in the offshore environment of the new jersey margin abstract sand ridges on the northeast us atlantic shelf form in the near shore environment most likely in response to storm driven flows as the holocene transgression has continued the ridges have been transferred to an offshore hydrodynamic regime where currents are not constrained by the coast and storms do not influence bottom currents as frequently or as strongly here we qualitatively and quantitatively investigate the morphology of offshore sand ridges and smaller scale features in an effort to place constraints on bedform development in these deeper waters a recent high resolution swath sonar survey mapped a portion of the new jersey shelf from 20 m water depth to the shelf break 120 m imaging both sand ridges and smaller scaled dunes and ribbons in far greater detail than has been previously possible using a robust statistical analysis we find that the gross morphology of ridges height width length does not change with depth beyond 20 m water depth and changes in ridge orientation generally mirror changes in regional contour orientation hence ridges have not continued to grow since transgression has brought them into the offshore hydrodynamic regime however on the inner shelf 20 m water depth to the mid shelf shore we do find evidence in the ridge shape which has an asymmetry opposite to that seen near shore and in the complex backscatter response that some important modifications to ridges are taking place at these water depths in contrast on the mid shelf from the mid shelf shore to the franklin shore ridges tend to have higher backscatter at the crests implying that these are largely winnowed relict features lineated smaller scale 100 500 m wavelength

between beds and sequences stratigraphic organization at intermediate scales in the quaternary of the virginia coast usa stratigraphy presupposes a hierarchy of scales of spatial organization supplemented at the small scale end by sedimentological concepts beds bed sets and bed cosets and at larger spatial scales by sequence stratigraphic concepts systems tracts parasequences sequences between these two end members are intermediate sclae bodies described as lithofacies or simply facies a more restricted concept granulometric facies can be described in terms of horizontal grain size gradients facies change and cvclic vertical grain size gradients stratification assemblages of facies so defined also called depositional systems are not random loot occur in a limited suite of patterns such assemblages may be linked to two classes of bounding surfaces a source diastem the immediate source of the sediment and a surface of closure if preserved between which is sandwiched a transgressive or regressive basinward fining facies succession systems bounding surfaces are notably more continuous than internal gradational facies boundaries by thus restricting the definition of a facies assemblage depositional system it is possible to describe the quaternary of the virginia coast wish as few as 12 systems depositional systems in the quaternary of the virginia coast are allometric in that any system can be derived from any other by plastic expansion of one or more facies relative to another or by simple symmetry operations self similarity prevails across this intermediate scale of stratigraphic organization facies assemblages depositional systems consist of event beds which themselves have erosional basal boundaries and internal successions of microfacies at larger spatial so ales depositional systems are repeated either autocyclic repetitions forced by processes within the basin of deposition or allocyclic repetitions as parasequences and high frequency sequences in the virginia quaternary systems architecture is compatible with sequence architecture and nests conformably within its framework but analysis of systems architecture reveals rules beyond those governing sequence architecture

paleoenvironmental evidence for latest pleistocene sea level fluctuations on the new jersey outer continental shelf combining high resolution sequence stratigraphy and foraminiferal analysis foraminiferal assemblages in vibracored sediments within 5 m of the seafloor document high resolution sea level fluctuations and confirm the complex quaternary depositional history of the new jersey margin biostratigraphic data have been integrated with ongoing 2 d 3 d high resolution seismic analyses to interpret paleoenvironments of surficial stratigraphy beneath the modern middle to outer shelf cluster analysis of foraminiferal assemblages sampled every 20 cm average define four sample groups a d dominated by benthic species group a characterized by cibicides lobatulus is a middle to outer shelf assemblage 60 100 m water depths group b is composed of middle shelf species 30 60 m water depths and is characterized by low abundances and a fairly uniform distribution of foraminifera which suggests reworking and or a high rate of sediment accumulation group c dominated by elphidium excavatum is an inner to middle shelf assemblage 10 40 m water depths group d present in only one core and dominated by ammonia beccarii represents marginal marine environments 0 10 m water depths with fluctuations in salinity in general the modern sedimentary veneer i e the upper 20 cm is characterized by the deeper water fauna of group a sediments below these modern deposits are characterized by groups b and c reflecting shallower water depths and variable sediment accumulation rates on the inner and middle shelf taken together the group succession in the cores suggests an overall se to nw landward transgression in these latest pleistocene holocene deposits seismic analysis indicates that one core 27 penetrates the flank of a buried channel including its fill and the pre channel section within the channel three alternations of groups c and d suggest fluctuations between marginal marine and middle shelf paleoenvironments high frequency perhaps very small 10 m changes in base level are indicated using previously published ams 14c dates these fluctuations can be constrained as having occurred between 45 000 yr b p channel incision and 12 500 yr b p channel filling suggesting the non uniform nature of the last wisconsinan deglaciation

seabed characterization on the new jersey middle and outer shelf correlatability and spatial variability of seafloor sediment properties abstract nearly 100 collocated grab samples and in situ 65 khz acoustic measurements were collected on the new jersey middle and outer shelf within an area that had previously been mapped with multibeam backscatter and bathymetry data and more recently with chirp seismic reflection profiling eighteen short cores were also collected and probed for resistivity based porosity measurements the combined data set provides a basis for empirically exploring the relationship among the remotely sensed data such as backscatter and reflection coefficients and directly measured seabed properties such as grain size distribution velocity attenuation and porosity we also investigate the spatial variability of these properties through semi variogram analysis to facilitate acoustic modeling of natural environmental variability grain size distributions on the new jersey shelf are commonly multi modal leading us to separately characterize coarse 4 mm fine

the role of erosion by fish in shaping topography around hudson submarine canyon abstract an 800 km2 area of rough topography around the head of hudson canyon off the eastern united states is attributed to erosion by tilefish lopholatilus chamaeleonticeps and associated species of crustaceans the rough topography has a relief of 1 10 m occurs in water depths of 120 500 m and has been cut into a semilithified silty clay substrate since the onset of the holocene transgression commercial fishing activity indicates that a large population of tilefish which dig burrows in the sea floor occupy the area of the rough topography average tilefish burrows are 1 6 m in diameter and 1 7 m in depth they have a clustered not uniform distribution and their average density is 2 500 per km2 the close match of areas of rough topography and high til fish populations the active burrowing of the sea floor and the clustered distribution of the burrows suggest that the hummocky topography in this area may be the result of continuous erosion by tilefish and associated crustaceans during the holocene an erosion rate of 13 cm per 1 000 years is necessary to create this topography during the past 13 000 years and 18 cm per 1 000 years if as is more likely based on the depths at which tilefish presently are found the erosion started 9 000 years ago

late quaternary sequence stratigraphy of a slowly subsiding passive margin new jersey continental shelf high resolution seismic profiles over a 25 000 km2 area off new jersey illustrate the effects of high amplitude high frequency eustasy on a slowly subsiding 0 2 mm yr passive margin analysis of 1600 km of geopulse uniboom minisparker and air gun profiles reveals four depositional sequences with a maximum total thickness of 100 m at the shelf edge correlation of these sequences to biostratigraphic and aminostratigraphic data from drill sites suggests all of these sequences may be post oxygen isotope stage 6 140 ka sequences i and iv appear to correspond to the major glacial interglacial sea level changes 120 m during oxygen isotope stages 6 5 and 2 1 respectively sequences ii and iii reflect smaller scale sea level fluctuations all sequence boundaries are interpreted as type 1 and sequences are predominantly composed of transgressive systems tracts tst and lowstand systems tracts lst much of the tst was deposited as incised valley fills parasequences in the tst commonly are isolated and fragmented the low subsidence rate and high frequency 20 k y eustatic oscillations result in extensive erosion and reworking of previously deposited sediments both by fluvial incision during lowstands and marine erosion during transgressions and highstands on continental margins where subsidence rates and sediment supply are low relative to rates of eustasy sequences are thin fragmented and difficult to correlate local effects such as shifting river drainage salt diapir movements and glacial isostasy can significantly influence sequence preservation on such margins

relict iceberg keel marks on the new jersey outer shelf southern hudson apron swath sonar bathymetry reveals sinuous furrows 400 m wide kilometers long and 4 m deep inscribed in semilithified clays on the southern hudson apron we interpret these as keel marks created by floating icebergs detached from the retreating laurentide ice sheet since ca 25 ka keel mark orientations suggest two phases of iceberg rafting these phases could correlate with heinrich meltwater events h2 and h1 ca 25 and 17 ka bracketing the late wisconsinan glacial maximum ca 22 ka during holocene transgression some keel marks were reworked and reformed into oblique ridges where older sandier sediments crop out at the seafloor relict glacial features on the new jersey outer shelf provide a tie between the timing of laurentide glacial retreat and the evolution of shallow stratigraphy on this mid latitude shelf during the last global sea level cycle ca 120 ka to present

shallow 3 d seismic reflection surveying data acquisition and preliminary processing strategies a comprehensive strategy of 3 d seismic reflection data acquisition and processing has been used in a study of glacial sediments deposited within a swiss mountain valley seismic data generated by a downhole shotgun source were recorded with single 30 hz geophones distributed at 3 m 3 m intervals across a 357 m 432 m area for most common midpoint cmp bins traces covering a full range of azimuths and source receiver distances of 2 to 125 m were recorded a common processing scheme was applied to the entire data set and to various subsets designed to simulate data volumes collected with lower density source and receiver patterns comparisons of seismic sections extracted from the processed 3 d subsets demonstrated that high fold 40 and densely spaced cmp bin sizes 3 m 3 m data with relatively large numbers 6 of traces recorded at short 20 m source receiver offsets were essential for obtaining clear images of the shallowest 100 ms reflecting horizons reflections rich in frequenci

the sedimentary record of the post glacial transgression on the gulf of cadiz continental shelf southwest spain abstract four seismic units ta to td have been identified from the analysis and interpretation of high resolution seismic profiles in a sector of the gulf of cadiz shelf they constitute a composite seismic unit attributed to the transgressive systems tract tst of the last depositional sequence the earliest transgressive unit was deposited on the outer shelf and represents the distal facies of a coastal deposit a process of shelf partitioning seems to have occurred during the formation of the three later transgressive parasequences the shelf sector offshore from the guadiana river mouth was a high energy environment dominated by storm events by contrast the shelf sector offshore from the donana national park was a low gradient shelf where large barrier island and lagoon systems were formed the sparse occurrence of marine deposits within the tst is a consequence of the episodic nature of the sea level rise the generation and preservation of these transgressive deposits results from the interaction of the following controlling processes 1 relative sea level rise the formation of coastal transgressive deposits is related to intervals of reduced sea level rise or stillstands within a period of continuous sea level rise those sea level changes were probably driven by short term periods of colder climate during the late pleistocene holocene deglaciation the younger dryas interval is the most widely recognised climatic event of this type but probably other events of similar characteristics had the same effect on the glacio eustatic sea level rise 2 sediment supply changes short lived climatic events probably also involved changes in the sediment supply to the continental shelf due to changes in erosion rates and river regimes of the river basin hinterlands 3 effect of the paleophysiography paleogeography the sedimentary environments differentiation processes are associated to the formation of an exposed coastal promontory offshore from the guadiana river mouth and a semi protected embayment offshore from donana national park this coastal configuration was controlled by previous tectonic evolution and influenced the non uniform landward migration of the coastline

quantitative reconstruction of paleoenvironmental conditions in the gulf of suez during the burdigalian langhian early to middle miocene using benthic foraminifera abstract in this study we examine a 750 m thick section of lower to middle miocene sediments penetrated by an exploration well named arm 36 drilled in the central eastern part of the gulf of suez we used the planktic foraminiferal biostratigraphy of this section to classify these sediments into four previously established planktic foraminiferal biozones m2 m3 m5 and m6 we then employed benthic foraminifera to describe the paleoenvironmental conditions in the gulf of suez and to correlate the results with other successions e g alpine foreland basin molasse basin altdorf section and the austrian part in the central paratethys the correlation indicates that similarities exist between the main paleoenvironmental events in the gulf of suez and central paratethys even though they were located in different climatic zones and were controlled by different tectonic events the similarities may be related to global climatic conditions consequently we applied several indices paleodepth proxies and multivariate statistics on 316 ditch samples containing 72 benthic species to reconstruct the paleoenvironmental conditions during this time interval analyses of benthic foraminifera and their ecological preferences indicate that these sediments were deposited in inner shelf to upper slope environments that were characterized by oxic bottom waters and normal marine salinity during the investigated interval

spot shallow water bathymetry of a moderately turbid tidal inlet based on field measurements the determination of shallow water depth in high energy tidal inlets is essential to model and to forecast the navigation channel position or the short term topographic evolution of beaches colour satellite imagery provides at low cost complete maps of areas that are difficult to map by traditional hydrographic means due to their size and their rough underwater morphology in order to calibrate spot images to derive bathymetric maps a simple method applied to shallow waters of a moderately turbid tidal inlet has been carried out its development is based on a set of field measurements including the reflectance of the water and of the bottom sediment the vertically averaged diffuse attenuation coefficient and the concentrations of inorganic particles in suspension of chlorophyll a and pheopigments and of dissolved organic carbon doc from these data it appears first that the water reflectance is directly linked to the depth and second that the water reflectance varies slowly with the turbidity in this area for total suspended matter sm concentrations lower than 9 mg l 1 the extinction of light with depth has been characterized in the inlet the relationship obtained is slightly different from that observed in clear waters the bathymetric models established for the clearest waters do not calculate the depth accurately in the contrary reflectance code adapted to case ii water type calibrated with in situ measurements allows us to retrieve depth down to 6 m and for total sm concentrations ranging from 0 2 to 9 mg l 1 this relationship has been applied to five spot images of the mouth of arcachon lagoon the accuracy of the derived map has been assessed by in situ depth measurements the mean difference between measured depths and computed depths is about 20 this accuracy is adequate to assess the inlet morphodynamics quantitatively which is necessary for middle term to short term mathematical modeling of the 3d inlet evolution

pleistocene climatic history reflected in planktonic foraminifera from odp site 1073 leg 174a new jersey margin nw atlantic ocean abstract abundance records of planktonic foraminifera 150 m from the upper 520 m of odp site 1073 hole 1073a leg 174a 639 m water depth have been integrated with specmap derived isotope stratigraphy percentage of calcium carbonate and coarse sediment fraction data in order to investigate the pleistocene climatic history of the new jersey margin six planktonic taxonomic groups dominate the foraminiferal assemblage at site 1073 neogloboquadrina pachyderma d mean 33 8 turborotalita quinqueloba 18 5 n pachyderma s 18 4 globigerina bulloides group 11 4 globorotalia inflata group 9 4 and globigerinita glutinata 4 1 based on the distributions of these six foraminiferal groups the pleistocene section can be divided into three paleoclimatic intervals interval i intermediate corresponds to the quaternary sediments from sequence boundary pp1 to the seafloor 79 5 0 mbsf emiliania huxleyi acme 85 ka at 72 mbsf interval ii warm occurs between sequence boundaries pp3 and pp1 325 79 5 mbsf last occurrence of pseudoemiliania lacunosa 460 ka at 330 mbsf and interval iii coldest occurs between sequence boundaries pp4 and pp3 520 325 mbsf calcareous nannofossils and dinocysts in proximity to pp4 indicate that the sedimentary record for 0 9 1 7 ma is either missing altogether or highly condensed within the basal few meters of the section neogloboquadrina pachyderma d displays eight peaks of abundance which correlate for the most part with depleted 18o values increases in calcium carbonate percentages low coarse fraction percentages increased planktonic fragmentation greater dissolution and low n pachyderma s abundances these intervals are interpreted as representing warmer interglacial conditions neogloboquadrina pachyderma s displays seven peaks of abundance which correlate for the most part with 18o increases decreases in calcium carbonate percentages increases in coarse fraction percentages and low n pachyderma d abundances these intervals are interpreted as representing cooler glacial conditions in interval iii a faunal response to relative changes in sea surface temperature is reflected by abundance peaks in neogloboquadrina pachyderma d followed by turborotalita quinqueloba and then n pachyderma s proceeding from warmest to coolest respectively this tripartite response is consistent with the oxygen isotope record and although not as clear also occurs in intervals i and ii six peaks peak intervals of globigerina bulloides abundance are closely matched by peaks in globigerinita glutinata and occur within oxygen isotope stage ois 2 latter part 3 4 5 8 9 13 14 and 15 we speculate that these intervals reflect increased upwelling and nutrient levels during both glacials and interglacials eight peak intervals of globorotalia inflata show a general inverse correlation with g bulloides and may reflect lowered nutrient and warmer surface waters

seaward branching coastal plain and piedmont incised valley systems through multiple sea level cycles late quaternary examples from mobile bay and mississippi sound u s a abstract most incised valleys become more organized seaward through tributaries merging with the main trunk valley late quaternary incised valleys on the mississippi and alabama inner continental shelf branch seaward although they do coalesce towards the shelf break where they feed shelf edge deltas to link fluvial systems with their associated previously mapped incised valleys on the shelf and evaluate the contribution of small coastal plain valley systems to the lowstand systems tract high resolution seismic data and cores were collected from mobile bay eastern mississippi sound and the mobile bay head delta these data show four unconformity bounded stacked units and this study focuses on the upper two regionally mappable units the upper two unconformities were sampled in core as exposure surfaces and on the basis of stratigraphic position depth of incision and 14c dates are interpreted as sequence boundaries the shallowest sequence boundary a formed in response to the oxygen isotope stage 2 sea level lowstand while the underlying sequence boundary b formed in response to an earlier lowstand stage 6 a map of sequence boundary b shows a network of seaward branching valleys 20 35 m deep and 0 6 7 7 km wide that extend across mobile bay and mississippi sound these valleys which are bounded by well developed terraces are extensions of the piedmont mobile fluvial system and the coastal plain fowl and la batre fluvial systems a map of the stage 2 sequence boundary shows that all systems generally reoccupied their previous valley positions and are separated by interfluve plateaus valley fill between sequence boundary b and the stage 2 sequence boundary is generally composed of a basal unit of alluvial sediments overlain by bay head delta deposits however stage 2 to 1 valley fill is composed entirely of central basin sediments the presence of bay head delta deposits on the inner shelf indicates this depositional environment backstepped across the estuaries to modern positions backstepping likely occurred as the low gradient paleovalleys were inundated resulting in rapid rates of transgression fluvial gradients measured on sequence boundary b and the stage 2 sequence boundary below the modern mobile bay head delta plain and the estuaries are very low 1 3 0 3 m km the mobile bay head delta and upper mobile bay are confined by steep topography which opens basinward into the low gradient shorelines surrounding lower mobile bay and mississippi sound during falling sea level channel branching likely occurred as the low gradient fluvial systems extended basinward beyond the confined topography these channels incised as sea level fell below the steeper shelf break during the lowstand stage 2 valley morphology is partially influenced by the position of the underlying stage 6 valleys both coastal plain and piedmont valley systems exhibit compound fill indicating that differentiation between these types of incised valleys cannot be based on valley fill architecture alone

measuring the shallow porosity structure of sediments on the continental shelf a comparison of an electromagnetic approach with cores and acoustic backscatter we validate estimates of shallow sedimentary porosities made on the continental shelf by electromagnetic methods through a comparison with those measured directly in cores specifically we show that an electromagnetic surveying system we have used to measure sediment resistivity in a number of seafloor locations returns porosity depth profiles that are related to those measured in cores and that our data have good sensitivity to the structure within the uppermost few tens of centimeters of seafloor we then consider inferences of sediment type made by observations of acoustic backscatter in the light of our porosity measurements our results suggest that electromagnetic methods provide complementary information that can be used to improve grain type estimates at and just below the seafloor especially when combined with acoustic backscatter data because the system is pulled along the seafloor data can be quickly collected from a large area of seafloor and can be used to interpolate facies conditions between core locations

towards high resolution 3d marine seismic surveying using boomer sources the use of boomer sources for 3d seismic imaging of shallow marine structures was investigated in a feasibility study boomers show sufficient stability to be used in multichannel seismic surveys the acquisition of a high frequency densely sampled seismic data volume was successfully performed in the baltic sea a pleistocene fluvial channel system and shallow gas accumulations were revealed beneath the unconsolidated sediments which constitute the sea floor in the southern kiel bay

observations of the r reflector and sediment interface reflection at the shallow water 06 central site acoustic bottom interacting measurements from the shallow water 06 experiment experiment frequency range 1 20khz are presented these are co located with coring and stratigraphic studies showing a thin 20cm higher sound speed layer overlaying a thicker 20m lower sound speed layer ending at a high impedance reflector r reflector reflections from the r reflector and analysis of the bottom reflection coefficient magnitude for the upper two sediment layers confirm both these features geoacoustic parameters are estimated dispersion effects addressed and forward modeling using the parabolic wave equation undertaken the reflection coefficient measurements suggest a nonlinear attenuation law for the thin layer of sandy sediments

elastic parabolic equation solutions for oceanic t wave generation and propagation from deep seismic sources oceanic t waves are earthquake signals that originate when elastic waves interact with the fluid elastic interface at the ocean bottom and are converted to acoustic waves in the ocean these waves propagate long distances in the sound fixing and ranging sofar channel and tend to be the largest observed arrivals from seismic events thus an understanding of their generation is important for event detection localization and source type discrimination recently benchmarked seismic self starting fields are used to generate elastic parabolic equation solutions that demonstrate generation and propagation of oceanic t waves in range dependent underwater acoustic environments both downward sloping and abyssal ocean range dependent environments are considered and results demonstrate conversion of elastic waves into water borne oceanic t waves examples demonstrating long range broadband t wave propagation in range dependent environments are shown these results confirm that elastic parabolic equation solutions are valuable for characterization of the relationships between t wave propagation and variations in range dependent bathymetry or elastic material parameters as well as for modeling t wave receptions at hydrophone arrays or coastal receiving stations

late quaternary sedimentation on the outer and middle new jersey continental shelf result of two local deglaciations high resolution seismic profiles show two prominent late quaternary sediment wedges on the outer and middle new jersey continental shelf an extensive wedge along the outermost shelf and upper slope up to 50 m thick appears to have been deposited on the hudson apron during an early melting of the late wisconsin laurentide ice sheet subsequent southward transport of this sediment occurred during sea level regression still stand and transgression a mid shelf sediment wedge which forms the fortune shore probably was deposited during a second melt event 11 to 12 ka as sea level was transgressing over the shelf

origin of step like and lobate seafloor features along the continental shelf off rio de janeiro state santos basin brazil a combined analysis of seismic and morphological features identified in a set of high resolution seismic reflection and bathymetric data shows a systematic relationship between major modern seafloor morphological traces and the basinward migration of late pleistocene coastlines along the continental shelf of the santos basin rio de janeiro state se brazil observed fairly continuous and sinuous mid outer shelf escarpments are related to the sea level variations and shelf exposure during the last glacial cycle a bathymetric step at 110 m is an erosional remnant of offlapping detached forced regressive wedges that spread over 50 km in the shelf dip direction probably developed during periods of falling sea level between mis 3 and 2 a second major escarpment at 130 m was interpreted as the shoreline during the lgm at the time of most extensive subaerial exposure of the continental shelf however a distal escarpment at 150 m is expressed as a straight contour feature along the two main shelf edge embayments that characterize the shelf break this escarpment is coupled with a basal seaward inclined and highly eroded ramp and was interpreted as the erosional action of bottom currents during the last transgression due to the displacement of the southward flowing brazil current towards the present day outer shelf previously published articles have regarded the morphological features observed on the modern shelf as indicators of stillstands during the post lgm transgression we conclude that on the contrary most of these features are actually from earlier parts of the late pleistocene and were formed in a regressive scenario under oscillating and relative slow sea level fall

between the tides modelling the elevation of australia s exposed intertidal zone at continental scale abstract the intertidal zone represents a critical transition between marine and terrestrial ecosystems supporting a complex mosaic of highly productive and biologically diverse habitats however our understanding of these important coastal environments is limited by a lack of spatially consistent topographic data which can be extremely challenging and costly to obtain at continental scale satellite remote sensing represents an important resource for monitoring extensive coastal zones previous approaches to modelling the elevation of the intertidal zone using earth observation eo data have been restricted to small study regions or have relied on manual image interpretation thus limiting their ability to be applied consistently over large geographic extents in this study we present an automated open source approach to generate satellite derived elevation data for over 15 387 km2 of intertidal terrain across the entire australian coastline our approach combines global tidal modelling with a 30 year time series archive of spatially and spectrally calibrated landsat satellite data managed within the digital earth australia dea platform the resulting national intertidal digital elevation model nidem dataset provides an unprecedented three dimensional representation of australia s vast exposed intertidal zone at 25 m spatial resolution we validate our model against lidar rtk gps and multibeam bathymetry datasets finding that modelled elevations are highly accurate across sandy beach 0 41 m rmse and tidal flat environments 0 39 m rmse model performance was least accurate 2 98 m rmse within rocky shores and reefs and other complex coastal environments with extreme and variable tidal regimes we discuss key challenges associated with modelling intertidal elevation including tidal model performance and biased observations from sun synchronous satellites and suggest future directions to improve the accuracy and utility of continental scale intertidal elevation modelling our model can be applied to tidally influenced coastal environments globally addressing a key gap between the availability of sub tidal bathymetry and terrestrial elevation data

late quaternary sedimentation off new jersey new results using 3 d seismic profiles and cores abstract regional seismic reflection surveys have delineated a wedge of late quaternary sediment extending 150 km south from the hudson apron along the edge of the continental shelf off new jersey the bottom of the sediment wedge is defined by a prominent reflector r assumed to represent an erosional surface carved during a low stand of sea level probably corresponding to the wisconsinan maximum glaciation a 3 d reflection survey of a 5 0 5 km area of the southern part of the wedge was carried out in october 1989 line spacing was 10 m and shot spacing 2 5 m navigation achieved position accuracies to the survey shows that the outer shelf sediment wedge has a complex internal structure unrelated to the present seafloor morphology the sedimentary sequence appears to have been formed by a series of depositional events related to glacial melting and interrupted by at least one erosional episode marked by a seismic surface that defines a system of meandering channels faunal studies of samples from cores indicate that the sediments were deposited at shallower depths than at present but there is no evidence for deposition in shallower water or closer proximity to land than the modern mid shelf it appears that the history of periglacial marine sedimentation which accompanied the post wisconsinan deglaciation is no less complex than its continental counterpart

anatomy of rapid margin progradation three dimensional geometries of miocene clinoforms new jersey margin documentation of along strike variations in the morphologies of continental margin clinoforms is essential for understanding mechanisms of progradation one of the fundamental relationships between depositional processes and preserved stratigraphy maps based on a grid of commercial multichannel seismic data offshore new jersey extending more than 70 km along strike and approximately 50 km downdip reveal the three dimensional morphology and evolution of four buried surfaces correlated with middle upper miocene sequence boundaries calibrated by drilling on the adjacent continental slope miocene clinoform breakpoints are not depositional analogs of the modern shelf edge they are linear to gently arcuate breakpoint and slope trends indicate a systematic southward displacement of depocenters over about 5 6 m y progradation responded to point fluvial sediment sources but efficient along strike sediment dispersal muted their influence canyons are absent on three of four clinoform slopes the fourth slope has one v shaped canyon and a broad erosional area possible slope failure planar floored canyons also occur albeit rarely seaward of clinoform toes apparently v shaped and planar floored canyons previously ascribed to downslope erosion vs slope failure headward erosion respectively can coexist the accretionary northern slope of little bahama bank is a possible morphologic analog by analogy with pleistocene shelf slope geometries an absence of canyons breaching clinoform breakpoints suggests that rivers did not discharge at paleoshelf edges indicating that sea level lowstands postulated for the middle upper miocene did not expose breakpoints reconstruction of breakpoint paleoelevations supports this conclusion for three of the four mapped surfaces suggesting that elevations of some miocene lowstands on the global sea level curve are too high by up to 60 m

buried paleo channels on the new jersey continental margin channel porosity structures from electromagnetic surveying abstract we report on a marine electromagnetic em survey across two portions of the new jersey continental margin that have been previously shown to contain buried paleo channels the em method used provides bulk porosity estimates to depths of around 20 m below the seafloor and is thus able to place porosity constraints on the nature of the channel infill and the contrast in physical properties across the channel boundaries our data show that a key condition for the channels to have an electrical signature is that they incise an underlying regional unconformity r thought to represent a subaerially eroded surface exposed during the late wisconsinan glaciation channels that cut r are seen through increases in apparent porosity another seismically imaged channel sequence which lies within the outer shelf sediment wedge sequence above r does not have an electrical signature indicating that the sediments above and below the channel boundaries have similar physical properties

shock loading experiments on eclogite samples of omphacitic eclogite from fattigau germany were shock loaded to pressures of 18 45 and 59 gpa the recovered specimens were investigated by x ray diffraction experiments and showed all those reflections typical of the well known high pressure phases the unusual appearence of the perovskite structured mgsio3 at the shock loading pressure of 18 gpa is in contrast to results of liu 1980 and could be attributed to strong nonequilibrium processes caused by shock waves

clastic sequences developed during late quaternary glacio eustatic sea level fluctuations on a passive margin example from the inner continental shelf near barnegat inlet new jersey analysis of 100 km of seismic reflection geopulse profiles from a 47 km 2 grid on the new jersey low mesotidal inner continental shelf near barnegat inlet reveals that the upper 30 m is composed of 3 unconformity bounded units vibracores 1 6 m long recovered from 12 sites contain several lithofacies reflecting a variety of depositional environments that existed during late quaternary glacioeustatic sea level fluctuations on this slowly subsiding passive margin with low sediment supply environments include rivers during glacial and stadial lowstands of the sea and a barrier island lagoon complex as well as pro barrier ebb tidal delta shore attached and detached ridges and below storm wave base shelf during interglacial or inter stadial highstands following the last major interglacial 125 ka sea level fell and rivers eroded a planar seaward dipping surface r1 by early wisconsinan time 70 ka as sea level rose during the mid wisconsinan 55 ka a barrier island system migrated to within 0 2 1 7 km of the modern barrier shoreline leaving a 4 to 6 m thick record depositional sequence i maximum highstand of the mid wisconsinan sea level was 20 m below present sea level fell again during the late wisconsinan 20 ka and rivers again flowed across the exposed shelf creating an unconformity r2 a barrier lagoonal system developed under rising sea level by at least early middle holocene time based on peats 8810 170 yr b p cored from 12 m the mid wisconsinan 55 ka barrier system was preserved under these early holocene transgressive sediments lower unit of depositional sequence ii lower transgressive tract the modern barrier and inner continental shelf deposits upper unit of depositional sequence ii upper transgressive tract are relatively thin average 3 4 m pebbly sands overlying a prominent unconformity a transgressive surface r3 formed by marine erosion during the holocene sea level rise both the ebb tidal delta and shore attached linear sand ridges act as partial shields to wave and tidal current erosion of the muddy sub strate below r3 in the nearshore area this shielding is creating a transgressive surface marine unconformity of relatively high relief 3 7 m

shallow water sediment properties derived from high frequency shear and interface waves low frequency sound propagation in shallow water environments is not restricted to the water column but also involves the subbottom thus as well as being important for geophysical description of the seabed subbottom velocity attenuation structure is essential input for predictive propagation models to estimate this structure bottom mounted sources and receivers were used to make measurements of shear and compressional wave propagation in shallow water sediments of the continental shelf usually where boreholes and high resolution reflection profiles give substantial supporting geologic information about the subsurface this colocation provides an opportunity to compare seismically determined estimates of physical properties of the seabed with the ground truth properties measurements were made in 1986 with source detector offsets up to 200 m producing shear wave velocity versus depth profiles of the upper 30 50 m of the seabed and p wave profiles to lesser depths measurements in 1988 were made with smaller source devices designed to emphasize higher frequencies and recorded by an array of 30 sensors spaced at 1 m intervals to improve spatial sampling and resolution of shallow structure these investigations with shear waves have shown that significant lateral and vertical variations in the physical properties of the shallow seabed are common and are principally created by erosional and depositional processes associated with glacial cycles and sea level oscillations during the quaternary when the seabed structure is relatively uniform over the length of the profiles the shear wave fields are well ordered and the matching of the data with full waveform synthetics has been successful producing velocity attenuation models consistent with the subsurface lithology indicated by coring results both body waves and interface waves have been modeled for velocity attenuation as a function of depth with the aid of synthetic seismograms and other analytical techniques some results give strong evidence of anisotropy and lateral heterogeneity in shear velocity of the upper 5 10 m of sediments and of extremely high velocity gradients in the topmost 1 2 m possibly exceeding 30 s 1

continental shelf morphology and stratigraphy offshore san onofre california the interplay between rates of eustatic change and sediment supply abstract new high resolution chirp seismic data acquired offshore san onofre southern california reveal that shelf sediment distribution and thickness are primarily controlled by eustatic sea level rise and sediment supply throughout the majority of the study region a prominent abrasion platform and associated shoreline cutoff are observed in the subsurface from 72 to 53 m below present sea level these erosional features appear to have formed between melt water pulse 1a and melt water pulse 1b when the rate of sea level rise was lower there are three distinct sedimentary units mapped above a regional angular unconformity interpreted to be the holocene transgressive surface in the seismic data unit i the deepest unit is interpreted as a lag deposit that infills a topographic low associated with an abrasion platform unit i thins seaward by downlap and pinches out landward against the shoreline cutoff unit ii is a mid shelf lag deposit formed from shallower eroded material and thins seaward by downlap and landward by onlap the youngest unit iii is interpreted to represent modern sediment deposition faults in the study area do not appear to offset the transgressive surface the newport inglewood rose canyon fault system is active in other regions to the south e g la jolla where it offsets the transgressive surface and creates seafloor relief several shoals observed along the transgressive surface could record minor deformation due to fault activity in the study area nevertheless our preferred interpretation is that the shoals are regions more resistant to erosion during marine transgression the cristianitos fault zone also causes a shoaling of the transgressive surface this may be from resistant antecedent topography due to an early phase of compression on the fault the cristianitos fault zone was previously defined as a down to the north normal fault but the folding and faulting architecture imaged in the chirp data are more consistent with a strike slip fault with a down to the northwest dip slip component a third area of shoaling is observed off of san mateo and san onofre creeks this shoaling has a constructional component and could be a relict delta or beach structure

stratigraphy and correlation of glacial deposits from indiana to new york and new jersey the quaternary glacial history of part of the region from indiana to new york and new jersey fig 1 was outlined in three summaries prepared for the vii congress of the international union for quaternary research wayne and zumberge 1965 goldthwait et al 1965 muller 1965 subsequent regional summaries by white 1969 1982 white et al 1969 ray 1974 and coates 1976 reviewed the entire succession of tills in parts of kentucky northeastern ohio pennsylvania and new york other syntheses and discussions by dreimanis and goldthwait 1973 evenson and dreimanis 1976 dreimanis 1977 fullerton 1980 mayewski etal 1981 and mickelson et al 1983 were concerned only with late wisconsin tills the glacial history of the region fig 2 and chart 1 is much more complex than was assumed in 1965 much of the new information is in unpublished theses and dissertations and other publications of limited distribution and it has not been summarized correlations in chart 1 are based primarily on stratigraphic relationships of tills and paleosols and secondarily on radiometric ages paleomagnetic polarity data and relativeage data this summary serves as an expanded explanation of chart 1 glacial events are discussed within a framework of time divisions from older to younger and by glacial lobes as shown in chart 1 paleomagnetic polarity data in chart 1 are from harrison and terasmae 1961 bleuer 1976 and pers commun johnson 1976 this volume and pers commun hoyer 1977 1983 and pers commun bonnett et al 1978 and teller and last 1981 sources of data related to named tills in indiana ohio pennsylvania new york and new jersey are listed in appendix 1 the term glacial lobe here is applied both to a regional physiographically controlled pattern of ice dispersal and to the geographic region influenced by such movement huron erie lobe glaciation includes ice movement from the georgian bay region ontario into the lake erie basin as well as ice movement through the lake huron basin into the lake erie basin fig 3 illinoian and pre illinoian tills throughout the region have not been well studied and they have no radio

nearshore sandbars crest position dynamics analysed based on earth observation data abstract understanding long term underwater sandbars dynamics is a key element for optimal coastal zone management but this endeavour is often held back by data availability in order to increase the spatial and temporal resolution availability and quality of sandbars observations this study proposes and evaluates a new approach for automatic extraction of sandbars positions from freely available satellite imagery using a case study of complex waters located on the danube delta coast black sea validation of the satellite extracted sandbars locations against 4 in situ measurements between 2016 and 2018 shows a very good correlation between the two datasets demonstrating the high accuracy of satellite derived data in revealing the underwater morphology of the upper shoreface along large areas and with high temporal resolution the obtained sandbars positions were then integrated into an automatic workflow able to accurately represent the seasonal and multi annual sandbars dynamics and also to give an insight about the sandbars alongshore behavioural changes the results are similar to the ones previously suggested by other studies which empowered different methods these prove the high potential of the newly proposed algorithm to be used for the automatic extraction of the positions of underwater features in the surf zone on other sites worldwide after proper tuning of parameters in accordance with local conditions the main constraints of the proposed approach are represented by the omission of sandbars position that imprint a low signal on the satellite image due to increased water depth especially for the outer bar high turbidity mostly for the inner bar or any other noise generation situation sun glint small wind waves the main advantages of the described algorithm are related to the simplicity of implementation and adaptability to other areas of interest and other types of satellite data

glacially influenced late pleistocene stratigraphy of a passive margin new jersey s record of the north american ice sheet abstract glacial isostasy and the sediment supply changes associated with the waxing and waning of ice sheets have dramatic effects on the stratigraphy of adjacent continental shelves in ancient stratigraphic records the glacial influences on such deposits could be difficult to recognize because of the removal of coeval terrestrial glacial deposits by erosion this study illustrates the effects of the laurentide ice sheet on a basin near its maximum limit the new jersey continental shelf analysis of 1600 km of geopulse uniboom minisparker and airgun profiles reveals four depositional sequences that have a maximum thickness of 75 m near the shelf edge sequences i and iv correspond to the major glacial interglacial sea level changes at marine isotope chron mic 6 5e and 2 1 whereas sequences ii and iii reflect smaller scale sea level fluctuations during chrons 4 3c and 3b 3a respectively sequences i and iv are characterized by relatively thick low stand to early transgressive deposits near the shelf edge formed during times of increased sediment supply but are thin and discontinuous across much of the shelf reflection horizons in these units deepen northward in the northern half of the study area due to collapse of a peripheral bulge that formed at the margin of the laurentide ice sheet the hudson river moved from a more southerly drainage pattern to the modern hudson shelf valley position possibly under the influence of the advancing peripheral bulge sequences ii and iii are largely preserved within a broad mid shelf swale likely created by the migration of an ancestral hudson river and their thickness implies much higher sedimentation rates during chrons 4 and 3 than seen today if the terrestrial glacial record was eroded the increased rates of sedimentation during the pleistocene dominance of sediments derived from northern new england and northward tilting of strata could be interpreted as a result of uplift of a northern source area the unusually high frequency of the relative sea level oscillations 20 kyr the concentration of sediment supply during low stands and early transgressions and the correspondence of sea level change with climatic change could be used to infer their relationship to a nearby ice sheet geologists studying deposits formed during times of widespread continental glaciation should consider possible glacial influences on the stratigraphy of mid latitude deposits even in the absence of sediments directly deposited by ice

magnetic anomaly map for northern western and eastern europe all of the available data describing the earth s magnetic field in northern western and eastern europe c 3 106 data points are compiled and presented at a scale of 1 20 400 000 the compilation meets two requirements i that the total field intensity anomalies reflect a survey acquired at an altitude of 3000 m above m s l and during the same epoch 1980 0 and ii that the anomalies are residuals after subtracting the common reference field dgrf1980 as the data span many epochs geomagnetic data recorded at observatories and repeat stations were used to determine the best model for estimating the secular variation in all data up to 1980 this yielded magnetic anomalies with wavelengths up to the order of 2000 km the precision of the resultant anomalies amplitudes about 1700 nt to 8000 nt differ between 10 nt in central europe and 20 nt in the outer parts of the compilation the resultant anomaly map contains a wealth of information to geoscientists studying global tectonic processes and the deep crustal composition of major continental crusts it clearly shows the different anomaly patterns between the palaeozoic and precambrian crusts of central and eastern europe these anomalies are interpreted as lateral changes of magnetization in a horizontal plate a comparison between the low level compilation and maps derived from the magsat satellite at about 360 km altitude allows the description of the two different crust types in europe

magnitude and timing of episodic sea level rise during the last deglaciation a succession of elevated ridge deposits on the south florida margin was mapped using high resolution seismic and side scan sonar imaging in water depths ranging from 50 to 124 m the ridges are interpreted to be subtidal shoal complexes and paleoshorelines eolian dune or beach formed during the last sea level transgression oolitic and skeletal grainstones and mixed skeletal peloidal ooid packstones were recovered using a research submersible all of the grains are of shallow water or intertidal origin and both marine and nonmarine cements were identified formation and preservation of these features are attributed to episodic and rapid changes in the rate of the deglacial sea level rise at the onset of the termination 1a 18o excursion this high resolution record of sea level change appears to be related to deglacial processes operating on submillennial time scales and supports increasing evidence of rapid episodic fluctuations in ice volume climate and ocean circulation patterns during glacial interglacial transitions

recent and modern marine erosion on the new jersey outer shelf abstract recent chirp seismic reflection data combined with multibeam bathymetry backscatter and analysis of grab samples and short cores provide evidence of significant recent erosion on the outer new jersey shelf the timing of erosion is constrained by two factors 1 truncation at the seafloor of what is interpreted to be the transgressive ravinement surface at the base of the surficial sand sheet and 2 truncation of apparently moribund sand ridges along erosional swales oriented parallel to the primary direction of modern bottom flow and oblique to the strike of the sand ridges these observations place the erosion in a marine setting post dating the passage of the shoreface ravinement and the evolution of sand ridges that form initially in the near shore environment also truncated by marine erosion are shallowly buried fluvial channel systems formed during the last glacial maximum and filled during the transgression and a regional reflector r that is 40 kyr depths of erosion range from a few meters to 10 m the seafloor within eroded areas is often marked by ribbon morphology seen primarily in the backscatter data as areas of alternating high and low backscatter elongated in the direction of primary bottom flow ribbons are more occasionally observed in the bathymetry where observed crests exhibit low backscatter and troughs exhibit high backscatter sampling reveals that the high backscatter areas of the ribbons consist of a trimodal admixture of mud sand and shell hash with a bimodal distribution of abraded and unabraded sand grains and microfauna the shell hash is interpreted to be an erosional lag while the muds and unabraded grains are in this non depositional environment evidence of recent erosion at the seafloor of previously undisturbed strata the lower backscatter areas of the ribbon morphology were found to be a well sorted medium sand unit only a few 10 s of cm thick overlying the shelly muddy sandy material concentrations of well rounded gravels and cobbles were also found in eroded areas with very high backscatter and at least one of these appears to be derived from the base of an eroded fluvial channel seafloor reworking over the transgressive evolution of the shelf appears to have switched from sand ridge evolution which is documented to 40 m water depth to more strictly erosional modification at greater water depths we suggest that this change may be related to the reduction with water depth in the effectiveness of sediment resuspension by waves resuspension is a critical factor in the grain size sorting during transport by bottom currents over large bedforms like sand ridges otherwise we speculate displacement of sand by unidirectional currents will erode the seafloor

seismic geomorphology of buried channel systems on the new jersey outer shelf assessing past environmental conditions abstract quantitative geomorphologic analysis of shallowly buried dendritic channel systems on the new jersey shelf provides estimates of paleo hydrologic parameters needed to link channel morphology to the former hydrodynamic setting these channels observed in 1 4 khz deep towed chirp seismic data formed presumably as fluvial systems when the shelf was exposed during the last glacial maximum lgm the presumed fluvial origin of these channels is supported by their incision into underlying pleistocene strata a chaotic seismic fill unit at their bases which may be indicative of non marine gravel lag and measured stream junction angles that are consistent with a riverine origin the channels would also have been subjected to estuarine tidal environments during ensuing sea level rise we employ empirically derived hydraulic equations for modern rivers and estuaries to estimate paleo discharges velocities and maximum shear stresses using the preserved and interpolated paleo channel geometries as a guide generally trunk main channels have box like symmetric cross sections with width depth ratios of 100 whereas smaller tributary channels have more v shaped asymmetric cross sections with width depth ratios of 40 70 the high width depth ratios along with low sinuosities 1 1 and slopes

lower pleistocene to present structural deformation and sequence stratigraphy of the continental shelf offshore eel river basin northern california seismic stratigraphic sequences and deformational features are mapped beneath the continental shelf of the offshore eel river basin of northern california using a closely spaced high resolution multichannel seismic grid geometries of sequences and morphologies of bounding unconformities reflect competing tectonic and glacioeustatic influences producing shifting sedimentation patterns in the offshore basin during the last v1 myr estimated timing of unconformity formation correlates generally with a deep ocean global n 18 o curve both before and after a v500kyr transition from 41 kyr to 100 kyr dominated cycles we suggest that glacioeustatic fluctuations are the dominant control on unconformity formation basinwide however regional tectonic influences on sequence development are also observed folding associated with gorda north america plate convergence ended progressively from south to north between v1 0 ma and v500 ka in response to northward migration of the mendocino triple junction mtj since v500 ka continued encroachment of the mtj produces rotation of preexisting structures uplift of the table bluff anticline tba related periods of channel incision south of the tba and generally reduced sediment preservation across the shelf mtj related uplift may also have induced formation of eel canyon over the past v1 0 myr a dominant northern sediment source becomes progressively less important a southern source probably the paleo eel river has become dominant since v750 ka seismic unconformities fall into two categories 1 irregular surfaces of limited mappable extent interpreted as incision exposure surfaces forming during relative sea level lowstands and 2 smooth laterally extensive regional unconformities interpreted as ravinement surfaces that erode lowstand surfaces in all but deeply incised areas during sea level transgressions a sequence stratigraphic model for sediment deposition and preservation on the eel river shelf predicts that preserved sediment on the eel margin is dominated by fluvially derived highstand silts and muds deposited by longshore directed currents and waves lowstand sediments are preserved only in fluvial channels infilled during late lowstand early transgression preserved transgressive sediments are likely limited to a thin veneer of well sorted coarse sediment or shell debris deposited above the transgressive ravinement future deep coring will be required to confirm these predictions 2002 elsevier science b v all rights reserved

monitoring shallow coastal environment using landsat altimetry data under rapid sea level change abstract the caspian sea cs is the largest enclosed inland body of water and eminent for its rapid sea level change from 1929 to 1955 rapid cyclic changes with amplitudes of 3 m led to the formation of large submerged and emerged areas the present study seeks to incorporate multi source sensor data such as the landsat time series data i e mss tm etm and oli alongside radar altimetry products i e topex jason 1 ostm jason 3 as a means for extracting morphological features gorgan bay and gomishan lagoon of the southeastern shorelines of the caspian sea as well as to investigate changes in the shoreline for a given period of 42 years 1975 2016 we also employ particle swarm optimization pso algorithm as an automated method to extract shoreline change in shallow marine environments over the past century the cs has experienced a lowstand in 1977 and a highstand in 1995 despite an approximate 1 5 m drop in sea level from 1995 to 2015 gorgan bay and gomishan lagoon with depths of 4 5 and 2 5 m appear to have outlasted and emerged respectively pso is a highly efficient method capable of defining shorelines and extracting water bodies the surface area estimations using the pso method are consistent with corresponding reference values with an average error of 1 73 and a high coefficient of determination r2 0 99 differences between calculated and reference areas were mainly observed in muddy and swamp sectors of the study area this study highlights the key role of satellite time series in shoreline monitoring and management under rapid sea level change conditions moreover the study demonstrates the capabilities of the pso algorithm as an automated and accurate method for shoreline detection

analysing decadal scale crescentic bar dynamics using satellite imagery a case study at anmok beach south korea abstract understanding long term sandbar dynamics can be crucial for informed coastal zone management but is often hampered by data availability to increase the number of sandbar observations available from bathymetric surveys this study proposes and evaluates a method to manually extract the sandbar location using freely available satellite imagery for the case study of anmok beach in south korea validation of the satellite extracted sandbar locations against 9 in situ measurements shows good agreement with errors well within the pixel resolution of the satellite imagery i e 30 m for landsat missions the applicability of the method is constrained to locations where 1 the cross shore crescentic length scales are larger than the image resolution 2 frequent wave breaking and clouds are absent and 3 the water clarity is sufficient to enable the manual extraction of the sandbar crest line using the additional sandbar observations from the satellite imagery significantly increases the temporal extent and resolution of the dataset for anmok beach this allows the study of sandbar characteristics dynamics and impacts of human interventions to an extent that would not have been possible without the satellite imagery within the study period 1990 2017 it is found that the sandbar maintains a persistent crescentic pattern that is only altered during prolonged and very intense storm conditions the cumulative alongshore migration of the sandbars is investigated and found to be in the order of hundreds of meters over the 27 years study period comparing the sandbar characteristics prior and after the construction of gangneung port shows that both the amplitudes and wavelengths of the sandbar crescents near the port have decreased after its construction

shoreline change mapping using crowd sourced smartphone images abstract shoreline change information is critical for effective management of the coastal zone this study presents a low cost method for mapping shoreline change that harnesses smartphone images collected by the community and uploaded to social media platforms a smartphone camera cradle installed overlooking a coastal region is used to constrain the crowd sourced camera extrinsic parameters and accompanying signage instructs participants on how to share their image to social media using a site specific hashtag identifier surveyed ground control points solve for the focal length of the smartphone lens and more accurately resolve the camera extrinsic parameters shoreline position is subsequently mapped on georectified images using an edge detection technique based on the red and blue colour channels a validation of the method was conducted at two sandy beaches in se australia and resulted in strong community participation 400 images submitted over 7 months by 198 individual contributors concurrent shoreline surveys using rtk gnss indicated that shoreline accuracy using this crowd sourced approach is comparable to that of established coastal imaging systems with cross shore shoreline accuracy best for these two elevated validation sites camera elevation 17 3 m 27 1 m above msl in the camera nearfield rmsd 1 4 m and rmsd ranging between 2 6 and 3 9 m over coastal stretches spanning up to 1 km minimal differences in shoreline accuracy were observed between low resolution images characteristic of those uploaded to social media and higher resolution images sourced from the smartphone the successful application of this low cost approach combined with the proliferation of smartphones and social media usage open up new possibilities for crowd sourced shoreline change mapping at suitable coastal locations worldwide

the last glacial insights from continuous coring on the new jersey continental shelf abstract sedimentation on the pleistocene new jersey nj shelf is complex and results from the interaction of processes chiefly driven by glacioeustatic change erosion non deposition downcutting and infilling combine to produce a complicated set of reflectors and sedimentary units that are best interpreted in the shallow subsurface with the aid of high resolution seismic reflection profiling the highly variable lithology on the shelf has historically been an impediment to significant core recovery in this challenging environment coring using the ahc 800 drilling system provided continuous downcore recovery at three sites on the outer shelf the sites targeted fluvial incisions channel fill and exposure surfaces associated with glacial lowstands the exceptional cores were analyzed using an integrated approach textural and benthic foraminiferal data were evaluated to determine the environment of deposition and estimate paleodepth carbon dating of wood and shell material provides the temporal framework for interpretation and k ar dating of hornblende crystals provides insights into the source region of sediments our integrated analysis indicates the nj shelf was a dynamic environment from at least 45 ka estimates of sea level from this study are consistent with other studies from the pleistocene nj margin the oldest sediments 36 k y recovered by drilling came from below site 3 and above site 1 r a time transgressive regional unconformity best estimates are for formation of r on the mid shelf between mis3b and the mis3b a transition 45 ka under neritic conditions channels were incised during late mis2 between 30 and 16 ka channel infill was focused in a narrow time frame during latest mis 2 16 14 ka shortly after the shoreline began to migrate landward rates of 1 2 cm yr are consistent with modern fluvial estuarine sedimentation rates reinvigoration and infilling of the channels around 14 ka is associated with meltwater pulse 1a we find no evidence at our study area for jokelhlaup deposition associated with the intra allerod cold period 13 ka regional deposition channel infill and interfluvial regions was underway by latest mis2 early mis1 as sea level transgressed the shelf the uppermost sediments are of holocene to recent age and are routinely and likely rapidly reworked eroded and mixed by shelf processes the sediment source during mis3 as determined by hornblende age dates was bimodal older sediments were derived from the reading prong nj highlands and younger sediments were sourced from along the hudson river delivery to the study area was through a more southerly paleo hudson position that may have resulted in formation of the outer shelf wedge through deltaic sedimentation during at least mis 3b 3a

deformation induced clinopyroxene fabrics from eclogites abstract clinopyroxene omphacite microfabric studies in eclogites are useful in characterizing the deformation that has affected deeper parts of subduction zones we present the microfabrics and tem structures of four samples representative of the various deformation types known in eclogites the 001 axis tends to be parallel to the lineation while the 010 plane is close to the foliation but these general features undergo strong variations in relation to the shape fabric in strongly lineated samples 010 tends to be spread out in a great circle normal to the lineation whereas 001 is dispersed in the foliation in the case of strongly foliated samples the slip systems identified by tem are 001 100 001 110 and 1 2 110 110 operation of dislocation creep is testified by the presence of dislocations and dislocation walls but this process alone cannot explain all the observed features particularly some aspects of the crystallographic preferred orientation hence other deformation mechanisms must be involved these may be dynamic migration recrystallization by grain boundary migration as well as mass transfer processes this study illustrates that not every crystallographic mineral preferred orientation can be explained by dislocation glide and or twinning processes alone in addition it also demonstrates that eclogite microfabrics can be used to unravel deformation parameters in subduction and or collision zones

estimation of shoreline position and change from satellite images considering tidal variation this paper presents the one line shift method of determining mean sea level datum based shoreline positions from three sequential satellite images that take into account tidal variations tidal correction through data interpolation on originally computed tides to accurately predict tidal level with a root mean squared error less than 10 cm the determined mean sea level datum based shoreline positions of the waisanding sandbar by the proposed method differ from those by rtk gps by about 43 09 193 58 m based on the acceptable shoreline positions from satellite images the whole area of the waisanding sandbar is proven to be decreasing since 1999 and migrating landward to the west of taiwan

basal inflection controlled shelf edge wedges off new jersey track sea level fall a key marker for examining the latest pleistocene history of the new jersey margin is the high amplitude long recognized r horizon reflector this time transgressive surface was formed 47 33 ka and represents the integrated topographic and bathymetric surface developed during the complicated sea level oscillation associated with the regression that preceded the last glacial maximum lgm from landward to seaward across the outer shelf the r reflector changes from subhorizontal in most locations 9 m beneath the modern seafloor to seaward dipping forming the base of two offlapping sediment wedges the previously described outer shelf wedge and a deep shelf wedge seaward of it this transition occurs across two inflection zones where the dip of the r reflector steepens seaward that can be traced for tens of kilometers along strike and mark the landward limits of these wedges these inflection zones are possibly former wave dominated shorefaces these represent the primary topographic elements present during the last regression we speculate that these inflections dictated both the locations for deposition of the two prograding offlapping wedges that developed during the complex sea level fall prior to the lgm and their successive erosion before and after the lgm we suggest that such inflection zones and their associated wedges are important markers of regression in clastic dominated outer shelf settings along passive margins

evaluating shoreline identification using optical satellite images abstract a technique to extract the shoreline location from optical satellite images has been developed and evaluated for the case study site of progreso yucatan mexico a novel method to extract a satellite derived shoreline sds was developed ensuring the maximum contrast between sea and land the area under investigation is an 8 km length of shoreline that faces north into the gulf of mexico the sds was validated using quasi simultaneous in situ shoreline measurements both adjusted to equal water levels in situ shoreline measurements recorded the instantaneous shoreward extent of the wave run up when walking along the beach the validation of sds revealed that the sds is located consistently seawards of the in situ shoreline explained by a the water depth that optical satellite image requires to identify a pixel either as sea or land and b the shoreward extent of the wave run up the overall distance between sds and in situ shoreline is 5 6 m on average with a standard deviation of 1 37 m in the horizontal over 8 km of shoreline confidence bounds considering the shoreward extent of the wave run up inter tidal beach slope variation and tidal uncertainty were computed to assess the accuracy of the sds the sds has been shown to be capable of detecting shoreline changes of less than 10 m and abrupt changes due to storms the success of our method suggests that it should be applicable to other locations after adapting the confidence bounds to the beach conditions

monitoring changing position of coastlines using thematic mapper imagery an example from the nile delta coastline movement due to erosion and deposition is a major concern for coastal zone management very dynamic coastlines such as sections of the nile delta coast pose considerable hazards to human use and development and rapid replicable techniques are required to update coastline maps of these areas and monitor rates of movement the synoptic capability of landsat thematic mapper imagery enables monitoring of large sections of coastline at relatively coarse 30 m spatial resolution by comparing positions of the nile delta coast in 1984 1987 and 1990 1991 mapped using a region growing image segmentation technique areas of rapid change can be identified and targeted for more detailed monitoring in the field or using higher resolution images rates of erosion and deposition can be estimated crudely and areas where change appears to be accelerating can also be identified areas of severe erosion along the nile delta coast are found to be confined to the promontories of the present day mouths of the nile at rosetta and damietta eroding shorelines are mostly flanked by accreting shorelines showing that some of the eroded material is redistributed along the coast the technique outlined here has potential to augment conventional field based surveying for monitoring shoreline changes over short timescales

drainage of late wisconsin glacial lakes and the morphology and late quaternary stratigraphy of the new jersey southern new england continental shelf and slope abstract we propose that late wisconsin deposition and erosion hudson shelf and block island valleys on the shelf and slope from new jersey to southern new england were a consequence of the catastrophic drainage of glacial lakes behind terminal moraine systems and the huge volume of water stored beneath the laurentian ice sheet and subsequent erosion of the lake sediments by flash floods the morphology imparted by glaciation regulated the discharge associated with the ablation of the glaciers associated with the deposits west of hudson shelf valley are the remains of mammoth and mastodon which were transported from their living habitats along the lake shores to their present burial sites on the shelf the floods also triggered gravity flows on the upper continental slope which made possible the transportation of coarse debris over hundreds of km into the deep sea that these catastrophic flood morphologies can still be recognized on the middle to outer shelf suggest that much of its surface was little modified during the late pleistocene holocene transgression thus the late pleistocene holocene transgression may have been characterized by short periods when sea level rose rapidly allowing for the preservation of relict features

forced regressive and lowstand hudson paleo delta system latest pliocene growth of the outer new jersey shelf abstract interpretation of the latest pleistocene stratigraphy of the outer new jersey shelf has evolved over the last three decades with addition of new geological and geophysical data during the last decade new results have described and interpreted various depositional elements within the latest pleistocene that overlie the regional reflector known as the r horizon on the basis of observations made from detailed mapping of the r horizon and the overlying sediment wedge s using high resolution shallow seismic chirp data acquired in several phases between 2001 and 2006 we revise the depositional model for the offlapping multi clinothem sediment wedge on the latest pleistocene outer new jersey shelf as strike elongated lobes of a falling stage wave influenced delta system fed by a pre lgm paleo hudson river channel s that probably reached the late pleistocene shelf edge off new jersey this sediment wedge is composed of a series of prograding and offlapping clinothems of varying thickness within our data which does not extend to the basinward termination of the wedge we seldom observe preserved topsets of these clinothems parts of the foresets of some clinothems are also not preserved particularly in the proximal part of the wedge the sediment wedge is elongated in strike direction nne ssw which suggests along strike sediment movement and possible redistribution of sediment in that direction by ambient shore parallel currents our data do not record any time equivalent fluvial channels at the proximal end of the sediment wedge though there are channel features that cap and cut down into several of the clinothems that make up the wedge farther seaward we suggest that this can be explained in two possible ways 1 relatively large spatial separation between the prograding front of the delta system and the delta plain topset deposits as is very common under a falling stage sea level condition and 2 lack of preservation of the stratigraphic record of the delta plain channels because of the likely vigorous falling stage erosion of topsets during the fall of sea level and possibly also during the subsequent transgressive ravinement and flooding after the lgm the clinothems within the sediment wedge show systematic variation in thickness indicating a northward shift of the main depocenter this shift might also be an indication of gradual northward migration of the principal fluvial feeder such a possibility is supported by previously reported late pleistocene paleo hudson channel deposits south of the modern hudson shelf valley

an ultrahigh resolution 3 d survey of the shallow subsurface on the continental shelf of new jersey regional seismic surveys have identified a wedge of late quaternary sediment extending 150 km south from the hudson river apron along the edge of the continental shelf off new jersey the bottom of the sediment wedge is defined by a prominent reflector that is assumed to be an erosional surface carved during a lowstand of sea level probably corresponding to the wisconsin maximum glaciation about 18 000 years ago an extremely high resolution 3 d seismic reflection survey of the southern part of the wedge figure 1 was carried out in 1993 as part of the strataform strata formation on margins initiative funded by the u s office of naval research

evaluation of storm impact on sandy beaches of the gulf of valencia using landsat imagery series abstract the impact of storms on sandy beaches and the subsequent recovery process is described from an analysis of the shoreline positions obtained from landsat 5 tm and landsat 7 etm imagery shoreline extraction is based on an algorithm previously proposed by the authors that enables a positioning accuracy of 5 m root mean square error rmse the impact of six storms registered over a period of seven months between november 2001 and may 2002 and the beach recovery processes until december 2002 across a 100 km segment of the gulf of valencia on the spanish mediterranean coast were analysed by comparing 12 shoreline positions the multiple shoreline positions obtained from landsat images provide very useful information for describing the impact of storms and the recovery process across large segments of microtidal coast this enables the identification of differences not only in the magnitude of change produced by a particular event but also in the cumulative effect associated with several storm events and in the study of how the beach recovery process takes place the results show a high level of spatial variability beaches with steep slopes experienced fewer changes than shallow slopes the existence of well developed foredunes in some areas minimised the reduction in the beach width after the storms coastal orientation was another important factor in explaining storm impact and the recovery process this factor affects not only the way the waves interact with the beaches but also the sediment longshore transport beach regeneration is slower when the transport of sediments is limited by artificial infrastructures groins jetties ports or natural sediment traps headlands the main limitations of using the proposed methodology to obtain the shoreline position from landsat images are related to i the precision in the shoreline detection ii the nature of the indicator obtained that is the water land interface and iii the registration instant defined by the image acquisition time however the high frequency of the data acquisition and the possibility to cover large coastal areas bring a new perspective that enriches other methods and tools used by coastal scientists