north atlantic subtropical mode waters and ocean memory in hadcm3 abstract a study of the formation and propagation of volume anomalies in north atlantic mode waters is presented based on 100 yr of monthly mean fields taken from the control run of the third hadley centre coupled ocean atmosphere gcm hadcm3 analysis of the temporal and spatial variability in the thickness between pairs of isothermal surfaces bounding the central temperature of the three main north atlantic subtropical mode waters shows that large scale variability in formation occurs over time scales ranging from 5 to 20 yr the largest formation anomalies are associated with a southward shift in the mixed layer isothermal distribution possibly due to changes in the gyre dynamics and or changes in the overlying wind field and air sea heat fluxes the persistence of these anomalies is shown to result from their subduction beneath the winter mixed layer base where they recirculate around the subtropical gyre in the background geostrophic flow anomalies in the warmest mode 18 c formed on the western

lateglacial and holocene environmental changes in portuguese coastal lagoons 1 the sedimentological and geochemical records of the santo andre coastal area the sedimentological and geochemical study of a core corresponding to sedimentation in the santo andre lowland since 14 000 bp allowed the reconstruction of environmental changes of this area and discussion of the relative importance of local versus global forcing factors responsible for its evolution the pre holocene section of the core represents terrestrial sedimentation in a fluviatile environment contemporaneous of a low sea level and a distal shoreline sediment inputs were terrestrial and resulting from intensive weathering and high erosion rate in the adjacent watershed during the early holocene c 10 020 to 5380 bp the sea invaded this lowland and defined an open marine shallow environment corresponding to a wide gulf which has been disturbed by multiple terrestrial inputs that might have been induced by massive episodes of fluvial discharge the first symptoms of confinement were noticed close to 5400 bp and c 5380 bp a major environmental threshold occurred possibly reflecting the marke

the western grand banks of newfoundland transgressive holocene sedimentation under the combined influence of waves and currents abstract the surficial sediments on the western grand banks of newfoundland have been reworked from older deposits primarily late wisconsinan glacial and glaciomarine sediments during the post glacial sea level fall and holocene rise winnowed medium to coarse sands and lag gravels that are generally less than 0 5 m thick chracterize the areas above the lowstand elevation at 110 to 120 m the holocene sediments which have accumulated in the deeper interbank channels isolated basins and on the upper continental slope are thicker and consists of the fine sands and muds that were removed from the banks the deposits below the lowstand elevation coarsen upward because little deposition occured during the sea level rise in general the holocene succession becomes thicker and finer grained to the south active sediment movement occurs at all depths less than about 110 m wave ripples composed of sandy gravel form to depths in excess of 100 m in response to long period 15 s surface waves but the predominant bedforms consist of current generated sand ribbons megaripples and sandwaves which exhibit unidirectional migration azimuths toward the southwest even though the storm current directions are highly variable and the maximum sediment transport rates are directed toward the east or southeast the bedform orientation and resultant transport are instead parallel to the southerly and southwesterly storm currents which occur during the prolonged post storm spin down period and to the weak 1 labrador current and the orbital motion associated with the largestwaaves thus the interaction of the oceanic current and wave orbital motion with the directionally variable strom currents is responsible for the consistent orientation of the current generated bedforms and for the distribution of holocene deposits

coherent heat patterns revealed by unsupervised classification of argo temperature profiles in the north atlantic ocean abstract a quantitative understanding of the integrated ocean heat content depends on our ability to determine how heat is distributed in the ocean and identify the associated coherent patterns this study demonstrates how this can be achieved using unsupervised classification of argo temperature profiles the classification method used is a gaussian mixture model gmm that decomposes the probability density function of a dataset into a weighted sum of gaussian modes it is determined that the north atlantic argo dataset of temperature profiles contains 8 groups of vertically coherent heat patterns or classes each of the temperature profile classes reveals unique and physically coherent heat distributions along the vertical axis a key result of this study is that when mapped in space each of the 8 classes is found to define an oceanic region even if no spatial information was used in the model determination the classification result is independent of the location and time of the argo profiles two classes show cold anomalies throughout the water column with amplitude decreasing with depth they are found to be localized in the subpolar gyre and along the poleward flank of the gulf stream and north atlantic current nac one class has nearly zero anomalies and a large spread throughout the water column it is found mostly along the nac one class has warm anomalies near the surface 50 m and cold ones below 200 m it is found in the tropical equatorial region the remaining four classes have warm anomalies throughout the water column one without depth dependance in the southeastern part of the subtropical gyre the other three with clear maximums at different depths 100 m 400 m and 1000 m these are found along the southern flank of the north equatorial current the western part of the subtropical gyre and over the west european basin these results are robust to both the seasonal variability and to method parameters such as the size of the analyzed domain

seasonal evolution of upper ocean horizontal structure and the remnant mixed layer 1 we discuss the seasonal evolution of upper ocean thermohaline structure at small horizontal scales the upper 350 m of a 1000 km long section in the subtropical north pacific was observed in winter spring and summer with 3 14 km horizontal resolution four vertical regions had distinct density and salinity structure the mixed layer remnant mixed layer high stratification layer and permanent thermocline the remnant mixed layer consists of water from the winter mixed layer left over after restratification the remnant mixed layer was most similar to the mixed layer in winter and spring and most similar to the high stratification layer below in summer the high stratification layer had elevated stratification that varied seasonally the permanent thermocline varied little seasonally and was horizontally and vertically uniform in comparison in all seasons density ratios showed that mixed layer s differences tended to compensate in density with the strongest tendency toward compensation in winter density ratios were temperature dominated in the remnant mixed layer consistent with salt fingering salinity anomalies were largest at the surface and decayed with depth in all seasons spectra of isopycnal depth and s anomalies along isopycnals are compared between the three seasons and four vertical layers isopycnal depth variance at 30 46 km wavelengths decreased from winter to spring to summer by a factor of 2 10 in stratified regions by treating salinity anomalies as a tracer the effective isopycnal diffusivity in the remnant mixed layer was estimated to be 1 4 m2 s 1 over 30 46 km wavelengths

geochemistry of the pond creek coal bed eastern kentucky coalfield the pond creek coal bed middle pennsylvanian breathitt formation is an important low sulfur resource in pike and martin countries in the eastern kentucky coalfield the mined area is crossed by the n20 e trending belfry anticline the pond creek coal bed has a higher sulfur content on the west side of the anticline the vertical trends in the ash geochemistry also vary across the anticline the sites to the east of the anticline represent deposition of peat through periods of relative stability with slow deposition bright lithotypes interspersed with periods of relatively rapid clastic deposition dull lithotypes both generally removed from marine influence comparison of elemental trends between the lowest bright lithotype and the second bright lithotype suggest that the swamp became less acidic with time an upward decrease in minor element concentration may be related to the influx of clays and other silicates present in the bone lithotype this bone may have acted as a relatively low nutrient soil for the growth of the plants which contributed to the overlying bright lithotype the sites to the west of the anticline were subjected to a greater marine influence than the eastern sites high k2o al2o3 ratios at the bottom and top of the coal bed and a high tio2 zr dull clarain near the bottom of the coal point to clastic influences on the geochemistry the relatively high cao percentages in the middle third of the coal bed suggest deposition at near neutral ph the upper third of the coal bed was dominated by syngenetic and epigenetic pyrite emplacement

a 1 year mesoscale simulation of the northeast atlantic mixed layer heat and mass budgets during the pomme experiment 1 a simplified oceanic model is used to perform a realistic yearlong simulation to study fine scale mixed layer processes in an area of the northeast atlantic 21 15 w 38 45 n during the programme ocean multidisciplinaire meso echelle pomme experiment september 2000 october 2001 this simplified three dimensional oceanic model is obtained by degenerating the primitive equations system by prescribing continuously analysis derived geostrophic currents ug called guide into the momentum equation by the substitution of the horizontal pressure gradient the realism of the simulated mesoscale structures was validated by a comparison with in situ mesoscale and submesoscale data and results from the geostrophic adjustment to the guide with this adjustment being applied at all scales this model was able to simulate energetic small horizontal scales taking place around stirring eddies and frontal regions moreover filamentary mixed layer depth structures were simulated and correlated to intense vertical velocities confined in the mixed layer the circulation structure during pomme consisted of three quasi permanent mesoscale eddies and a front the mixed layer heat and mass budgets were thus strongly driven by the horizontal advection and the vertical transport associated with this mesoscale circulation although no effective detrainment or entrainment occurred at the domain scale three regions were found to be the site of intense detrainment around anticyclonic and cyclonic mesoscale eddies and along an axis of strong currents in which the lateral induction and the vertical velocity at the mixed layer base are the major components driving the detrainment respectively

lateral variation in geochemistry petrology and palynology in the elswick coal bed pike county kentucky abstract the middle pennsylvanian langsettian westphalian a elswick coal bed correlative to the upper banner of virginia is a rare example of a mined high sulfur 2 coal in eastern kentucky a region known for low sulfur coals to characterize lateral variation in the geochemistry petrography and palynology of the elswick coal bed three sites were sampled along a southeast northwest transect within a single mine at the southeastern site the lower 101 cm of the 116 cm thick coal is dull generally dominated by durain and dull clarain while all benches at this site fit within the previously defined mixed palynoflora moderate low vitrinite group suggesting a stressed environment of deposition the palynology of the benches of the dull interval show greater diversity than might be expected just from the petrology lithology is generally similar between the sites but each site has some differences in the petrology overall the coal bed shows significant lateral variation in properties at the mine scale some of which can be attributed to the gain or loss of upper and lower lithologies either through an actual physical merging or through the change in character of lithotypes sulfur content varies between the three sites examined for this study site 3 located in the northwestern portion of the study area is characterized by a strikingly high sulfur zone 7 45 in the middle of the coal bed a feature missing at the other sites pyrite and marcasite in a mid seam lithotype at the northwestern site site 3 show signs of overgrowths indicating multiple generations of sulfide emplacement the high sulfur site 3 lithologies all have massive overgrowths of euhedral and framboidal pyrite fracture and cleat fill pyrite and sulfide emplacement in fusinite lumens sulfur is high throughout the mine area but variations are evident in the extent of secondary growth of sulfides

decadal water mass variations along 20 w in the northeastern atlantic ocean abstract water mass variations in the northeastern atlantic ocean along 20 w are analyzed with pentadal resolution over the past 15 years using data from four repeat occupations of a meridional hydrographic section running south from iceland the section was sampled in 1988 1993 1998 and 2003 the results are interpreted in the context of changes in air sea forcing ocean circulation and water properties associated with the north atlantic oscillation nao the nao index oscillated around zero from 1984 to 1988 was strongly positive from 1989 to 1995 after which it shifted to lower positive and occasionally negative values from 1996 to 2003 previously published studies suggest that after the 1995 1996 shift of the nao the subpolar gyre largely retreated to the northwest in the northeastern atlantic ocean resulting in an increasingly southeastern character of local water masses with time water property changes extending from the subpolar mode water spmw just below the seasonal pycnocline through the density range shared by mediterranean outflow water and subarctic intermediate water saiw along 20 w are consistent with changes in wind driven ocean circulation and air sea heat flux associated with shifts in the nao especially after accounting for ocean memory after periods of lower nao index the spmw is warmer saltier and lighter at these same times large increases of apparent oxygen utilization aou and potential vorticity are found at the spmw base consistent with spmw ventilation to lighter densities during lower nao index periods deeper and denser in the water column the cold fresh and dense saiw signature within the permanent pycnocline that was most strongly present in 1993 near the culmination of a period of high nao index is much reduced in 1988 and 1998 in 2003 after a prolonged period of lower nao index increasing influence of warmer saltier subtropical waters is clear within the permanent pycnocline the deep penetration of the changes implies that they are caused primarily by circulation changes resulting from nao associated wind shifts but changes in air sea heat flux could also have played a role

a simplified 3d oceanic model assimilating geostrophic currents application to the pomme experiment abstract a simplified oceanic model is developed to easily perform cheap and realistic mesoscale simulations on an annual scale this simplified three dimensional oceanic model is obtained by degenerating the primitive equations system by prescribing continuously analysis derived geostrophic currents ug into the momentum equation in substitution of the horizontal pressure gradient simplification is provided by a time sequence of ug called guide which is used as a low resolution and low frequency interpolator this model is thus necessarily coupled to systems providing geostrophic currents that is ocean circulation models analyzed reanalyzed fields or climatologies in this model the mass and currents fields are constrained to adjust to the geostrophic guide at all scales the vertical velocity is deduced from the vorticity equation which ensures the coherence between the vertical motion and the geostrophic structures evolution horizontal and vertical advection are the coupling processes that can b

palynological evidence for holocene environmental change in the changjiang yangtze river delta china abstract holocene vegetation changes in response to climate fluctuations and human impacts are reviewed on the basis of pollen analyses from borehole cores taken from the changjiang yangtze river delta china and other previously reported data during the earliest holocene 10 930 9000 cal yr bp the climate was warm and wet allowing thermophilous hardwoods to occupy mid and low elevations surrounding a palaeo changjiang estuary the climate became gradually cooler and cool tolerant conifers grasses and ferns became dominant until 7600 cal yr bp when the estuary became a delta a mid holocene climatic optimum occurred between 7600 and 4800 cal yr bp when evergreen and broadleaved deciduous trees flourished at mid and low elevations surrounding the delta front prodelta after this time climate became cooler again until 1340 cal yr bp during this period evergreen and broadleaved deciduous trees were replaced by conifers and grasses inhabiting the inter subtidal flat delta front this development of conifer grassland vegetation was shortly interrupted between 3860 and 3200 cal yr bp when thermophilous tree cover increased and open vegetation with scattered conifers was reduced since 1340 cal yr bp the vegetation has been similar to that at present under warm wet conditions human impacts are recognized by the first appearance of fagopyrum and a sudden increase in herb pollen at 4500 and 1340 cal yr bp respectively

production regimes in the northeast atlantic a study based on sea viewing wide field of view sensor seawifs chlorophyll and ocean general circulation model mixed layer depth 1 a 5 year time series of sea viewing wide field of view sensor seawifs ocean color images schl is compared with mixed layer depths mld and atmospheric forcings from the clipper model of the north atlantic 1998 2002 this comparison is done over the region 16 22 w 30 50 n where subpolar mode waters are formed and which overlaps the region of the 2001 programme ocean multidisciplinaire meso echelle pomme experiment at sea three production regimes are identified on the basis of the seasonal cycling of schl and mld the well known subpolar and subtropical regimes and a midlatitude regime the midlatitude regime is characterized by a single broad bloom weaker than the subpolar spring bloom and stronger than the subtropical fall bloom which starts in fall as an entrainment bloom and peaks in spring as a restratification bloom this specific regime is found between 35 n and 40 n 2 in the northeast atlantic it corresponds to winter mlds between ze the depth of the euphotic layer and 2ze i e it lays between the region where the winter mld is greater than sverdrup s critical depth subpolar regime and the region where the mixing is never deeper than the well lit layer subtropical regime the very specific characteristics of the midlatitude regime strengthen the biological carbon pump since production is active in winter within the waters to be subducted the midlatitude regime also may provide an explanation for the unexpectedly low f ratios sometimes observed during the bloom in the region north atlantic bloom experiment pomme a large interannual variability is observed for the three regimes in terms of the timing and the intensity of the blooms and of the geographical boundaries of the regimes these variabilities appear to be mainly driven by the synoptic and the low frequency atmospheric variabilities it is also shown that in addition to the northward propagation of the subpolar spring bloom from 41 n 1 3 to 50 n the fall entrainment bloom propagates southward over the whole latitudinal range 35 50 n

tidal strait to embayment seismic stratigraphy and evolution of a rock bounded embayment in the context of holocene sea level change abstract elongate rock framed santa catarina island partly encloses a low energy marine embayment that communicates with the ocean via narrow rock bounded inlets with ebb and flood tide deltas the bay shoreline consists of low energy sandy beaches strandplains mangroves and bayhead deltas while the exposed atlantic shoreline comprises a series of headland embayment littoral cells in a linked north directed longshore drift system new and previously published seismic stratigraphic investigations enable assessment of the palaeogeographic geomorphic evolution of the area since the early holocene at a sea level of ca 50 m a sandy mainland attached shoreline complex dune and beach developed on a coastal plain setting some 6 7 km offshore of the present shoreline north of the island a barrier island and tombolo were formed in a coastal re entrant adjacent to the northern entrance to florianopolis bay the open coast beach dune system was overstepped by rapid sea level rise during mwp 1b whereas the barrier island and tombolo continued to accrete until mwp 1c when they too were overstepped the back island embayment contains up to 40 m of sediment overlying an irregular bedrock surface it was initially flooded during mwp 1c and the early muddy sedimentation suggests a distal sheltered marine embayment the subsequent development of many large bioherms on bedrock and mud suggests a change to more fully marine conditions as sea level continued to rise in the north bay these were subsequently enveloped by tidal dunes migrating north from the mid bay the vertical stacking of 3 d and 2 d sandy bedforms suggests that a tidal strait had developed with strong tidal currents radiating from a constriction in the vicinity of modern florianopolis city the strong tidal currents may be linked to the holocene sea level high that is well documented for this region a fall in sea level from this highstand coupled with accumulation of tidal strait sediments reduced the tidal prism and strength of tidal currents in the bay at the same time regressive beachridge plains developed in open coast and bay environments this coincided with development of the contemporary tidal inlet complexes at the north and south outlets of the bay as a consequence the upper surface of the tidal strait sand deposits experienced tidal ravinement and the bay switched to a sheltered back barrier environment dominated by deposition of mud and silt which blanket the contemporary bay floor the tidal inlets sequestered sand from the littoral drift system in ebb and flood tide deltas which created breaks in the longshore drift system causing littoral sediment to accumulate at the north of the island in a series of spits and promoting strandplain development south of the island

sedimentary evidence of intense hurricane strikes from new jersey nine vibracores from the backbarrier marsh at whale beach new jersey reveal three large scale overwash deposits associated with historic and prehistoric storms the uppermost and smallest overwash fan was deposited in the ash wednesday northeaster of march 5 8 1962 a second more substantial overwash fan between 100 and 35 cm depth dates to the late eighteenth or early nineteenth century this fan was most likely deposited during the 1821 hurricane the only intense hurricane to make landfall in new jersey in the past 350 yr a third larger overwash fan between 200 and 300 cm depth was deposited between a d 1278 and 1438 and is likely the result of a prehistoric intense hurricane strike the combination of historical and stratigraphic evidence indicates that two intense hurricanes winds 50 ms 21 have likely made landfall on the southern new jersey coast in the past 700 yr resulting in an annual landfall probability of 0 3

siltation of river influenced coastal environments respective impact of late holocene land use and high frequency climate changes abstract the aim of this study is to unravel the respective influence of land use and high frequency climate changes on the siltation of a river influenced coastal environment an 8 4 m long sediment core was recovered in the pertuis charentais western france an accurate 14 c bayesian age model was developed to perform a depth to time conversion of high resolution sedimentological data obtained on the core forest loss and precipitation changes that occurred on the related catchments were reconstructed from data gathered in the literature a sharp increase in winter rainfall 1700 1750 ad intensified erosion of catchments previously sensitised by increased forest loss 1640 1710 ad which resulted in a massive supply of silt to the coast from ca 1775 ad onwards a review of articles reporting similar mud layers is also proposed depending on their age some major phases of mankind migration history could be traced back which confirms the predominant influence of human activities on the siltation of river influenced coastal environments we therefore propose to group these mud layers into the anthropogenic system tracts in reference to widely used sequence stratigraphy nomenclature and we suggest that it might help to identify a holocene to anthropocene stratigraphic boundary in coastal areas

coal facies studies in the eastern united states coals in the eastern united states east of the mississippi river have been the subject of a number of coal facies studies going back to the 19th century such studies would not necessarily fall within a strict modern classification of coal facies studies but if a study encompassed some aspects of paleobotany palynology petrology geochemistry or sedimentology we assumed that some data and interpretations may be of use in evaluations of the facies references are presented as a guide for further research with annotation in the tables

metalliferous coals of the westphalian a joggins formation cumberland basin nova scotia canada petrology geochemistry and palynology abstract five coals of westphalian a early middle pennsylvanian age were sampled from the joggins formation section exposed along chignecto bay at joggins nova scotia coal beds along the bay were mined beginning in the early 17th century yet there have been few detailed published investigation of the coal beds of this classic section the lowermost coal the upper coal 28 upper fundy is a high vitrinite coal with a spore assemblage dominated by arboreous lycopsid spores with tree ferns subdominant the upper portions of the coal bed have the highest ratio of well preserved to poorly preserved telinite of any of the coals investigated coal 19 clam coal has 88 total vitrinite but unlike the fundy coal bed the telinite has a poor preservation ratio and half the total vitrinite population comprises gelocollinite and vitrodetrinite the latter coal bed is directly overlain by a basin wide limestone bed the lower kimberly coal shows good preservation of vitrinite with relatively abundant telinite among the total vitrinite the middle kimberly coal which underlies the tetrapod bearing lycopsid trees found by lyell and dawson in 1852 exhibits an upward decrease in arboreous lycopod spores and an upward increase in the tree fern spore punctatisporites minutus telinite preservation increases upwards in the middle kimberly but overall is well below the preservation ratio of the upper fundy coal bed the coals all have high sulfur contents yielding up to 13 7 total sulfur for the lower lithotype of the upper fundy coal bed the kimberly coals are not only high in total and pyritic sulfur but also have high concentrations of chalcophile elements zinc ranging up to 15 000 ppm ash basis is present as sphalerite in fusain lumens arsenic and lead each exceed 6000 ppm ash basis in separate lithotypes of the kimberly coals together these data are consistent with elevated ph in planar mires the source of the elemental enrichment in this presumed continental section is enigmatic

a three dimensional ocean mesoscale simulation using data from the semaphore experiment mixed layer heat budget a primitive equation model is used to simulate the mesoscale circulation associated with a portion of the azores front investigated during the intensive observation period iop of the structure des echanges mer atmosphere proprietes des heterogeneites oceaniques recherche experimentale semaphore experiment in fall 1993 the model is a mesoscale version of the ocean general circulation model ogcm developed at the laboratoire d oceanographie dynamique et de climatologie lodyc in paris and includes open lateral boundaries a 1 5 level order turbulence closure scheme and fine mesh resolution 0 11 for latitude and 0 09 for longitude the atmospheric forcing is provided by satellite data for the solar and infrared fluxes and by analyzed or reanalyzed for the wind atmospheric data from the european centre for medium range weather forecasts ecmwf forecast model the extended data set collected during the iop of semaphore enables a detailed initialization of the model a coupling with the rest of the basin through time dependent open boundaries and a model data comparison for validation the analysis of model outputs indicates that most features are in good agreement with independent available observations the surface front evolution is subject to an intense deformation different from that of the deep front system which evolves only weakly an estimate of the upper layer heat budget is performed during the 22 days of the integration of the model each term of this budget is analyzed according to various atmospheric events that occurred during the experiment such as the passage of a strong storm this facilitates extended estimates of mixed layer or relevant surface processes beyond those which are obtainable directly from observations surface fluxes represent 54 of the heat loss in the mixed layer and 70 in the top 100 m layer while vertical transport at the mixed layer bottom accounts for 31 and three dimensional processes account for 14

a portable coring device for use in the intertidal environment abstract the construction of a portable coring unit with a telescopic tube and stationary piston mounted on a tripod frame is described using the procedure outlined it is possible to core unconsolidated sediments clay and sands in intertidal environments with the minimum of disturbance down to depths of 6 m

contrasting sediment records of marine submersion events related to wave exposure southwest france abstract sediment records of two contrasting backshore coastal marshes extremely vulnerable to recent and historical marine flooding events located on the sw coast of france have been investigated using a multiproxy approach the studied marshes are 30 km apart and have been flooded by similar storm events 7 marine floods in the last 250 years one is located in a wave exposed coast but isolated from the sea by a sediment barrier whereas the other is located in a sheltered estuarine environment and isolated from the sea by a dike one core was collected in each marsh and information on grain size foraminifera shell contents and stable carbon isotopes was obtained along with an age model using 210 pb 137 cs and 14 c core data combined with historical maps give evidence of a typical estuarine backfilling part of the holocene regressive parasequence including an intertidal mudflat at the base and a backshore environment at the top despite the absence of grain size anomalies marine flood related sedimentation in the backshore area of both marshes is identified by a mixture of marine and terrestrial features including marine fauna vegetation debris and variation in the 13 c signature of the organic fraction very low sedimentation rates between flood events and or bioturbation prevents the identification of individual episodic marine floods in the sediment succession comparison of the two sedimentary successions shows that the foraminifera deposited by marine submersions are of two different types foraminifera are monospecific and originate from the upper tidal mudflat in the sheltered marsh whereas in the backshore marsh located in a wave exposed environment they show higher diversity and originate from both shallow and deeper water marine environments this study shows that wave exposure can control the faunal content of marine flood sediment records in coastal marshes

palynologic and petrographic variation in the pond creek coal bed pike county kentucky abstract recent studies of the petrology and ash geochemistry of the pond creek coal bed middle pennsylvanian breathitt formation in pike and martin countries kentucky have defined vertical and lateral trends that are related to the development of the northeast trending belfry anticline contemporaneous with the deposition of the pond creek peat to the northwest of the anticline the coal bed has a high caco3 middle zone and a high fe2o3 high sulfur upper zone to the east of the anticline particularly in the lick creek and jamboree 7 1 2 quadrangles the coal bed exhibits a distinctive petrographic zonation in the latter area the usual megascopic sequence is a basal durain followed by a bright clarain durain dull the palynology of the pond creek coal bed was investigated in six sets of bench lithotype samples from the lick creek and jamboree 7 1 2 quadrangles the low vitrinite basal durain zone 1 has a palynomorph assemblage which reflects the importance of tree ferns and herbaceous lycopods the easternmost site has a bright clarain below the durain the latter lithotype has a fair diversity of palynormph groups and also has the highest percentage of arborescent lycopod forms of any bench below the bone zone 5 the bright zone 2 above the durain has the greatest maceral group range and the greatest floral diversity of any of the lithotypes the zone 3 dull lithotype has increased amounts of herbaceous lycopods and decreased amounts of arborescent lycopods sphenopsids and tree ferns the zone 4 bright lithotypes are generally over 80 vitrinite and in general exhibit a dominance of arborescent lycopods although sphenopsid tree fern and small fern forms exhibit varying importance the high ash bone zone 5 has 71 6 77 0 vitrinite this lithotype is marked by a dominance of herbaceous lycopods at the expense of arborescent lycopods and sphenopsids the zone 6 bright clarian is marked by an increase in arborescent lycopods and a large decrease in herbaceous lycopods the low vitrinite terminal durain has an assemblage with high percentages of herbaceous lycopods and low percentages of arborescent lycopods as well as increase in tree fern spores over zone 6 in general the petrology and palynology trends are predictable dull lithotypes have abundant herbaceous lycopod representation and bright lithotypes have abundant arborescent lycopod representation the greatest deviation from this simple pattern is within the zone 4 bright lithotypes where diverse palynomorph assemblages occur among the high vitrinite benches overall the greatest floral diversity appears to have occurred near the base of the coal bed

buried sandbodies within present day estuaries atlantic coast of france revealed by very high resolution seismic surveys abstract studies of sandbanks within estuaries and macrotidal bays are critical for management of those coastal environments where human activity concentrates they are also excellent analogues of reservoirs new very high resolution vhr seismic profilers are now available for studying at the outcrop resolution scale sandbodies in very shallow water we present here a vhr seismic study constrained by vibrocores repetitive bathymetric surveys and radiocarbon dating which provide evidence of buried sandbodies in mixed tide and wave influenced estuaries of the french atlantic coast the three selected buried sandbodies are chosen because they are located at various water depths and have different internal architecture and outer shape they include 1 a very shallow water around 2 m under low tide elongated nearshore sandbody emplaced during the last centuries 2 a 6 to 7 m deep elongated nearshore sandbody dated to 2965 30 bp and 3 sandwaves lying around 17 m of water depth over the top of a large rounded shape sandbody dated to 5260 30 bp deepest 6 and 17 m sandbodies are interpreted as remnants of lower sea levels and thus transgressive sandbodies all those sandbodies are buried under estuarine mud which have been mainly emplaced during the last millenium such major sedimentary transition from basal sand to upper mud is assumed to record a major environmental change in relation to both natural infilling of estuaries climate change and increasing human activities anthropogenic perturbations are however believed to be the most important factor they have mainly consisted of land reclamation and are responsible for 1 rapid infilling of tidal bays 2 tidal prism and tidal current energy decreases and 3 deposition of muddy sediments upon sandbodies

silica fluxes in the northeast atlantic frontal zone of mode water formation 38 45 n 16 22 w in 2001 2002 1 the biogenic bsi and lithogenic lsi silica export fluxes were investigated in the northeast atlantic 38 45 n 16 22 w as part of the programme ocean multidisciplinaire meso echelle pomme program in 2001 2002 they were measured at four stations located on both sides of a frontal zone 40 42 n by means of permanent moorings of sediment traps deployed at 400 and 1000 m depth averaged over the area the annual bsi fluxes corrected from 230th trapping efficiencies ranged between 0 240 mmol m 2 d 1 at 400 m to 0 316 mmol m 2 d 1 at 1000 m the bulk annual bsi fluxes are comparable to bulk bsi export fluxes recorded for oligotrophic areas the annual export flux of lsi range 0 029 mmol m 2 d 1 at 400 m to 0 054 mmol m 2 d 1 at 1000 m was lower than bsi and accounted for 10 of the total silica export flux results show a strong coupling between the two siliceous particulate fractions which is interpreted as reflecting lsi scavenging by bsi and limitation of bsi production in surface water by lithogenic trace metals inputs bsi export was maximum at the beginning of the productive season during the spring bloom however annual bsi export fluxes in 2001 were quite higher at 400 m in the southern area e g 0 249 0 288 at the southeast station versus 0 211 mmol bsi m 2 d 1 at the northeast station contradictory to the classical south north surface production increase we suggest an advective lateral transport within the upper 400 m of siliceous particles from the northern more productive area to the southern region

on the origin of the warm inflow to the nordic seas abstract warm and saline waters enter the nordic seas from the south as part of the warm to cold water transformation of the thermohaline circulation of the northern north atlantic one explanation for the origin of the nordic seas inflow is a shallow source hypothesis under which the inflow waters are a modification of upper ocean subtropical waters warm waters from the subtropical gyre are carried to the eastern north atlantic by the north atlantic current and branch northwards joined by poleward upper thermocline flow along the upper continental slope to provide the nordic seas inflow along this pathway the upper water column is progressively cooled and freshened by winter convection the subpolar mode water transformation process and this sets the inflow characteristics a deep source hypothesis provides an alternative explanation for the characteristics of the nordic seas inflow and the pathway delivering the waters to the inflow under this hypothesis inflow waters originate from the core of the mediterranean overflow waters in the gulf of cadiz carried northward at mid depth by the eastern boundary undercurrent in the subtropics continuing into the subpolar gyre along the eastern boundary and rising from depths near 1200m in the rockall trough to less than 600m to cross the wyville thomson ridge into the faroe shetland channel and thence to the nordic seas the deep source hypothesis focus is on lower thermocline source waters beneath the sill depth for the nordic seas inflow in contrast to the shallow source hypothesis focus of transformation of upper thermocline waters above the sill depth on the basis of regional water mass distributions geostrophic shear and direct current measurements we reject the deep source hypothesis in favor of the shallow source hypothesis rather than a flow of deep mediterranean overflow water along the eastern boundary rising from depth to feed the nordic seas the inflow is supplied directly by transformed north atlantic current waters from the same depth range as the inflow mediterranean overflow water is a constituent of the inflow but only through its contribution to defining the temperature salinity relationship of the interior of the subtropical gyre from which the north atlantic current draws its water rather than by direct northward advection of mediterranean outflow water via the eastern boundary undercurrent crossing from the subtropics into the subpolar domain instead the eastern boundary undercurrent wholly expels its transport of mediterranean overflow water into the eastern edge of the subtropical gyre creating the mid depth westward extending subtropical salinity plume for the lower thermocline isopycnal range of the core of the mediterranean overflow water measurements show that at the wyville thomson ridge the flow is southward and descending rather than northward and rising representing cold spillover from the faroese channels entraining warm upper ocean waters as the spillover plume descends and warms into the northern rockall trough no evidence is found in rockall trough northward of 54 n porcupine bank for direct advection of mediterranean overflow waters via an eastern boundary undercurrent extension and the very dilute mediterranean overflow waters in the trough reflect the interaction of the wyville thomson ridge plume descending into the trough from the north and lower thermocline waters delivered to the trough from the south

control of relative sea level and climate on coal character in the westphalian c atokan four corners formation central appalachian basin u s a abstract peat successions preserved as coal seams preserve high resolution records of ancient terrestrial water table base level fluctuations that are driven by changes in relative sea level and or paleoclimatic change the aim of this study is to establish the roles of relative sea level and climate in controlling water table fluctuations within coal seams from the fluviodeltaic westphalian c bolsovian atokan four corners formation of the central appalachian basin usa comparison of the characteristics of 10 coals in the four corners formation with accommodation trends identified from analysis of intra coal clastic strata indicates that their thickness and vitrinite inertinite ratio correlate readily with the accommodation setting of the depositional sequence in which they occur coals that accumulated in relatively high accommodation fourth order sequences are high in vitrinite thin and overlain by or intercalated with marine and lacustrine sediments the coals have simple internal organization suggesting that they span parts of single high resolution accommodation cycles coals that accumulated in lower accommodation fourth order sequences are high in inertinite thick and overlain by or intercalated with terrestrial sediments the coals have composite internal organizations typified by multiple high resolution accommodation cycles and characteristic abrupt discontinuities of coal facies representing periods of depositional hiatus the correlations between the composition and thickness of the coals and the magnitude of associated marine transgression imply that relative sea level change was the principal control governing bulk accommodation in these mires landward of the paleoshoreline high frequency accommodation cycles within the coals reflect water table fluctuations in the original mires and were driven by high frequency sea level and or climate change the results of this study provide considerable insight into the manner in which coal composition and stratigraphy at a single locality vary over time in response to changing accommodation and provide a means to predict coal seam quality in an established sequence stratigraphic framework

sand spit rhythmic development a potential record of wave climate variations arcay spit western coast of france abstract this study aims at showing the sedimentary and geomorphological records of wave climate variations by spits the studied spit arcay spit is located on the french atlantic coast and has displayed a rapid elongation since the beginning of the 19th century that potentially represents a two century long wave climate record wave climate and spit growth relationships are studied from two complementary methods 1 numerical modelling of wave and longshore transport temporal and spatial variabilities and 2 morphological monitoring based on the analysis of 4 historical maps 1811 1945 8 aerial photographs 1945 2000 and 17 satellite spot images 1987 2005 results at seasonal to interannual time scales show that the sand spit area gain variations are the result of variations in longshore transport themselves modulated mainly by wave height moreover energetic swells seem to cause massive sand accumulation and spit elongation whereas less energetic swells appear to be responsible for small sand accumulation and spit curvature at longer time scale decades to centuries increasing spit growth phases are also synchronised with periods of energetic swells or high storm surge frequency these results suggest that wave climate variations are the main factor controlling spit morphological evolutions

three dimensional reservoir characterization and flow simulation of heterolithic tidal sandstones tidal sandstone reservoirs contain significant intervals of hydrocarbon bearing heterolithic facies characterized by the presence of tide generated sedimentary structures such as flaser wavy and lenticular bedding millimeter to centimeter sand mud alternations we have characterized the reservoir properties sandstone connectivity effective permeability and displacement efficiency of these facies using three dimensional 3 d models reconstructed directly from large rock specimens the models are significantly larger than a core plug but smaller than a typical reservoir model grid block we find that the key control on reservoir quality is the connectivity and continuity of the sandstone and mudstone layers if the sandstone layers form a connected network they are likely to be productive even at low values of net to gross about 0 30 5 this may explain why the productivity of low net to gross heterolithic tidal sandstones is commonly underestimated or overlooked connectivity is the dominant control on the transition between productive pay and nonproductive nonpay heterolithic facies however connectivity is difficult to characterize because core plugs sampled from the subsurface are too small to capture connectivity whereas two dimensional outcrop measurements can significantly underestimate the true 3 d value our results suggest that core plug measurements of permeability and displacement efficiency are unlikely to yield representative values at the scale of a reservoir model grid block because the connectivity and continuity of sandstone and mudstone layers varies significantly with length scale

seaward pinching out and internal stratigraphy of the gironde incised valley on the shelf bay of biscay abstract an incised paleovalley offshore the estuary mouth of the gironde river southwest france was evidenced recently comptes rendus de l academie des sciences de paris 326 1998 701 nevertheless its seaward extension to the shelf break was still unknown new high resolution geophysical data were acquired on the continental shelf in order to follow the incision until the shelf break after processing the seismic lines the shape of the valley was identified and the valley fill in terms of sequence stratigraphy was interpreted the valley fill contains a single sequence corresponding to a fifth order cycle 20 kyr the three systems tracks described onshore by allen and posamentier journal of sedimentary petrology 63 1993 378 sepm society for sedimentary geology special publication tulsa 1994 225 are present offshore the lowstand is poorly developed and is only present in the proximal part of the incised valley the transgressive systems tract tst constitutes the bulk of the valley fill it is composed of landward prograding estuarine clinoforms in the distal part of the valley early tst phase 1 and of landward migrating tidal inlet fill deposits in the proximal part of the valley late tst phase 2 the thin early highstand systems tracts hst strata downlap seaward onto the maximum flooding surface and caps the tst as expected in this wave and tide dominated environment the tidal and wave ravinement surfaces which bound the tst are particularly well developed the valley incision tapers 50 km offshore of the estuary mouth the depth of the basal sequence boundary gradually decreases seaward and is locally truncated by the wave ravinement surface around 70 m below the mean sea level these observations indicate that during the lowstand times rivers do not always generate continuous cross shelf incised valleys they may adjust to a rapid drop in base level by modifying their channel morphology i e deep large channels located upstream change downstream to shallow anastomosed channels with a weaker erosional ability therefore the lowstand fluvial channels will be poorly developed and will eventually died out in the proximal part of the shelf because they are unable to keep pace with a phase of rapid sea level drop similar observations have already been reported for the english channel paleoriver geological society special publication london 1996 203 these de geologie marine universite de bordeaux 1 1997 265

stirring of the northeast atlantic spring bloom a lagrangian analysis based on multisatellite data 1 the effect of the geostrophic stirring on phytoplankton variability during the northeast atlantic spring bloom is studied by analyzing satellite derived surface chlorophyll sea surface temperature and sea surface height the calculation of unstable manifolds is used as a diagnostic of the transport properties of the geostrophic velocity field calculated from the sea surface height we identify two mechanisms by which the geostrophic velocity field acts on chlorophyll patterns the first mechanism is a direct effect of the horizontal transport on already formed chlorophyll by acting as sticking transport barriers the unstable manifolds are shown to 1 modulate the fronts of already formed phytoplankton in lobular structures 2 create spiralling chlorophyll anomalies within eddies and 3 produce chlorophyll filaments the second mechanism is an indirect effect on in situ chlorophyll production mediated by nutrient upwelling supported by a recent study on the vertical velocities of the northeast atlantic legal et al 2006 we argue that the horizontal unstable manifolds also shape the filamentary vertical velocity cells and hence the patterns of in situ produced chlorophyll through submesoscale vertical nutrient injection

chemical signatures of palaeotsunamis a forgotten proxy article i nfo article history a range of diagnostic criteria are required to help identify palaeotsunami deposits although chemical signatures have long been used as indicators of palaeosalinity in sedimentary sequences their use in the studies of palaeotsunami deposits is rarely applied and is yet to be widely recognised the chemical composition of interstitial water in coastal ponds and sedimentary sequences in coastal marshes and lagoons has been used successfullyasanindicatoroftsunamiinundation chemicalsignaturescanalsoprovidecluesaboutthelandward limit of runup of a tsunami beyond the area of sediment deposition like most palaeotsunami proxies however the preservation of chemical signatures varies with environmental conditions

facies associations detrital clay grain coats and mineralogical characterization of the gironde estuary tidal bars a modern analogue for deeply buried estuarine sandstone reservoirs abstract estuarine tidal bar sandstones are complex reservoir geobodies commonly exploited by the oil and gas industry in order to better predict the reservoir potential of these geobodies this study provides a modern day reservoir analogue describing tidal bars in the inner and outer gironde estuary from the microscopic to the macroscopic scale the originality of this work lies in the multi scale study of modern estuarine tidal bars based on numerous piston cores extracted in a high energy environment this work demonstrates that these tidal bars are composite sedimentary bodies made up of individual reservoir sand units separated by thick muddy layers their vertical facies associations and internal architectures are controlled by local hydrodynamic variations and seasonal river influxes detrital clay grain coats are notably characterized using a portable and handheld mineral spectrometer from the base to the top of the tidal bars x ray diffraction and electron microscopes reveal that these coats are mainly composed of di octahedral smectite illite chlorite and kaolinite associated with other components such as diatoms or pyrite the best reservoir geobodies are those with the minimum clay permeability barriers at the macro and mesoscale an optimum coated grain content and clay fraction volume is also needed for generating authigenic clay coatings and inhibiting quartz overgrowth these conditions are met within the tidal sand bars of the outer estuary funnel that are expected to be the best reservoir geobodies in deeply buried sandstones

formation of deep incisions into tide dominated river deltas implications for the stratigraphy of the sego sandstone book cliffs utah u s a abstract the upper cretaceous sego member of the mancos shale in east central utah is composed of tidally deposited sandstones interbedded with intervals containing marine shales and thin wave deposited sandstones the tidal sandstones have been interpreted to comprise multiple amalgamated estuarine valley fills above a major sequence boundary that is incised into distal marine deposits of the underlying buck tongue shale according to this interpretation the deposits constitute the base of a thick transgressive succession within the sevier foreland clastic wedge alternatively lower sego sandstones have recently been interpreted by the authors to be tide dominated river delta deposits in an overall regressive interval of the foreland succession a cross section showing facies variations and stratigraphic surfaces within the lower sego member along 100 kilometers of the eastern book cliffs is used in this paper to refine depositional and sequence stratigraphic interpretations of these tidal deposits particularly the origin of deep incisions within the sego sandstones a strike oriented section of the lower sego member reveals tidal sandstone lenses 40 50 kilometers wide and tens of meters thick separated laterally by areas tens of kilometers wide that have no tidal sandstones facies variations within the tidal sandstones reflect depositional processes on tide dominated deltas that prograded obliquely into the shallow intracratonic western interior seaway of north america two major episodes of delta progradation and subsequent transgressions are interpreted to have formed tidal sandstone layers within the lower sego sandstone thinner tidal sandstone layers of more local extent are interpreted to reflect changes in tidal current strength but not necessarily shifts in shoreline position or major changes in water depth multiple origins are suggested for incised erosion surfaces within the lower sego sandstones firstly the tide dominated deltaic sandstones are floored by laterally discontinuous erosion surfaces these basal surfaces marking abrupt vertical changes in depositional process and coarsening of grain size are interpreted to record tidal scouring of the sea floor during shoreline progradation secondly sharp based upward coarsening deltaic sandstones are cut by numerous deep incisions with tens of meters of relief and locally they are entirely removed by erosion some of this deep erosion within the lower sego sandstone may reflect the upstream avulsion of incised distributaries during forced regression of deltas into the basin whereas others may have formed by tidal erosion of abandoned distributaries during more gradual progradation and subsequent retrogradation of deltas highly variable facies trends within incision fills are related to pronounced changes in sediment supply to different distributaries on the delta to differences between incisions cut during delta regression versus those cut during the start of transgression and to varying distances from delta axes when the entire coast was transgressed the influence of tides waned and wave generated currents ravined delta tops depositional interpretations of the sego member indicate that the buck tongue to neslen interval lies in a broadly regressive part of the foreland basin fill

geochemistry of the blue gem coal bed knox county kentucky abstract the blue gem coal bed middle pennsylvanian westphalian b breathitt formation has low ash with some sample sites having less than 1 ash and low sulfur contents through parts of knox county kentucky most collection sites exhibit similar vertical elemental trends in ash geochemistry the relatively high ash 1 ash lower part of the bed displays enrichment in tio2 zr cr v and ni co zn rb and mn show enrichment at some sites a low ash 1 ash and a relative enrichment in sio2 k2o and rb and a relative decrease in cu ni co ba and mn when compared to the middle part of the bed principal components analysis indicates that the samples with an ash content 0 63 1 0 show associations for ni cu cr and co samples with between 1 01 2 0 ash display strong element associations that suggest increased clastic sediment contributions tio2 zr k2o rb sio2 the low ash content and the upwards decrease in trace concentrations both suggest that the blue gem peat swamp was ombrotrophic through at least a part of its geologic history

a high resolution simulation of the ocean during the pomme experiment mesoscale variability and near surface processes 1 this article is the second part of a modeling study of upper ocean mesoscale physical processes in an area of the northeast atlantic that was extensively sampled during the programme ocean multidisciplinaire meso echelle pomme experiment october 2000 september 2001 the model is a high resolution regional version of the ocean general circulation model opa integrated from february to may 2001 the mesoscale upper ocean dynamics has been carefully validated in a first paper paci et al 2005 in the present article the simulation is used to analyze the contribution of mesoscale eddies to the mixed layer processes during the period that controls the annual subduction rate and the characteristics of the subducted water mesoscale eddies account for a significant part of the mixed layer heat salt and water budgets through mesoscale and submesoscale structures acting on the horizontal advective terms they represent respectively 52 and 66 of the horizontal advection of temperature and salinity and 70 of the lateral induction they also induce an earlier and more intense restratification the domain averaged detrainment appears to be reduced by more than 15 by mesoscale eddies and reaches about 0 8 sv however these eddies increase the density of the detrained water some dense water likely to be involved in the formation of subpolar mode water is detrained by them in a way that maximizes its chance to be effectively subducted in the area

mangrove bank sedimentation in a mesotidal environment with large sediment supply gulf of papua the most extensive mangrove forests on earth are associated with major river systems the indo pacific region has numerous large rivers that discharge onto broad continental shelves and mangroves occur widely along these coastlines in the gulf of papua gop alone there are 3350 km2 of mangrove forests the majority of which 2900 km2 are associated with the fly kikori and purari river deltas this study examines data from 28 vibracores to describe preserved sedimentary strata and to determine rates of sediment accumulation in this dynamic coastal environment the observations suggest a common stratigraphy is contained in prograding mangrove banks of the mesotidal western gop and that it is similar to mud dominated and physically stratified stratigraphy recorded by other intertidal areas with and without mangroves experiencing large tidal range 2 m and sediment supply e g ganges brahmaputra and yangtze river deltas grain size sedimentary structure radionuclide and remotely sensed data are analyzed and four stratigraphic facies are identified 1 supratidal to high tidal muds 2 mid tidal sandy muds 3 low tidal sand and mud and 4 subtidal channel sands supratidal and high tidal sediments of gop mangrove forests are typically muddy but can have high sand contents 30 in areas exposed regularly to ocean waves these muds can be homogenous but commonly have physical structures laminations and bedding probably reflecting high rates of sediment accumulation relative to bioturbation mangrove muds may have low water contents due to infrequent inundation and because of their cohesive nature and abundant roots can form steep intertidal banks and erosional scarps mid tidal and low tidal sediments are thinly laminated 2 mm laminations likely deposited from fluid mud transport channel sediments have thin and thick mud and sand laminations but are identified by thick 5 cm sand beds a conceptual model of mangrove bank progradation is created using sedimentological and radionuclide data maximum sediment accumulation rates were determined using steady state 210pb profiles and greatest mean rates are found in mid tidal areas 4 4 cm year 3 9 g cm2 year slower accumulation occurs in high tidal and low tidal areas 1 8 and 1 5 cm year respectively 1 2 and 1 0 g cm2 year respectively remotely sensed data indicate that areas of erosion and accretion co exist in the kikori purari region very large 210pb accumulation rates were measured in areas of significant accretion supporting the validity of the calculated rates in areas of rapid accretion cores can have non steady state or event related 210pb profiles reflecting episodic sedimentation or complex radionuclide scavenging dynamics most cores from the fly river delta are of this type sediment trapping in western gop mangroves is estimated to account for 2 14 of the total gop sediment load

clay minerals and geochemistry record from northwest mediterranean coastal lagoon sequence implications for paleostorm reconstruction abstract the paleostorm history of coastal lagoon environments pierre blanche lagoon central part of the gulf of lions has been established by integrating clay mineralogy and geochemical analysis clay mineralogy combined with bulk major and trace elements concentrations allow for the definition of four different end members the mosson drainage basin the sandy barrier the biogenic and the anthropic components the two main sedimentary sources of the lagoonal system are the mosson drainage basin which has a high concentration of smectite and al 2 o 3 and the sandy barrier characterized by high contents of illite chlorite sio 2 and zr smectite illite chlorite sio 2 al 2 o 3 and zr al 2 o 3 ratios can be used to reconstruct the past storm history of the pierre blanche lagoon our results indicate that the sensitivities of the clay mineralogy and geochemistry proxies are different these sensitivities could be related 1 first to the comparison between different grain size for geochemistry and for clay mineralogy 2 second to the complexity of the mix four end members for the geochemistry and two end members for the clay minerals and 3 third by the storm s ability to transport sediment of different sizes

impact of relative sea level changes since the last deglaciation on the formation of a composite paraglacial barrier abstract comprehensive onshore offshore surficial and sub surface mapping of a composite barrier combination of prograded aggraded and or transgressive segments have provided a better understanding of the i mechanisms responsible for the formation and development of coastal barrier systems ii relationships and interactions among individual parts of those systems and ii the overall stratigraphic framework of subaerial and subaqueous segments of the barriers here we investigate these facets of barrier evolution through integration of stratigraphic data from subaqueous high resolution seismic and subaerial ground penetrating radar sedimentology terrestrial cores and seafloor surface samples and merged topographic and bathymetric mapping of the miquelon langlade barrier northwest atlantic ocean south of newfoundland this barrier system has two open coasts and evolved in a paraglacial setting influenced by the reworking of glaciogenic sediment glacial moraines in a regime of complex sea level changes the barrier stratigraphic sequence is placed within the context of a shifting period from shoreline transgression to one of regression the resulting sedimentary units reflect the isolated position of the saint pierre and miquelon archipelago distal from continental influence seismic profiles reveal the position of the lowstand shoreline located 20 25 m below modern sea level further refining the existing lowstand model of southern newfoundland continuous onshore offshore subsurface geophysical mapping of the barrier allows for the identification of the relative positioning of distinct sedimentary units interpreted as subaerial barrier beaches dunes spit shoals and shoreface deposits and allows for estimation of the total barrier sediment volume 235 106 m3 and its relative subaqueous 90 and subaerial 10 components moreover it reveals the three distinct morphological units comprising the holocene barrier i central regressive swash aligned beach ridge plains developed atop both thin westward prograding and thick eastward prograding shoreface deposits ii drift aligned elongating spits located in the northwest and northeast of the island and iii a transgressive barrier located adjacent to the northwest spit pinned on its landward side to parabolic sand dunes and currently experiencing erosion and limited overwash finally this study places evolution of this system in the framework of paraglacial barrier evolutionary typology

foraminiferal microhabitats in a high marsh consequences for reconstructing past sea levels abstract the foraminiferal faunas of the high marsh of plougoumelen in the western part of the gulf of morbihan on the french atlantic coast have been studied in three successive sample sets taken in weekly intervals in april 2001 each sampling day four cores have been taken in different marsh environments with or without vegetation in order to determine the microhabitat of the major species and the eventual influence of a vegetation cover physico chemical parameters have been surveyed during each sampling day the foraminiferal faunas are similar to other faunas described from temperate salt marshes we have distinguished three groups of taxa with different microhabitats a jadammina macrescens is found in comparable numbers down to about 9 cm depth b shallow infaunal taxa such as miliammina fusca and trochammina inflata and c deep infaunal taxa such as haplophragmoides wilberti and arenoparrella mexicana although these deep infaunal taxa have to cope with low oxygen concentrations or even anoxia life at depth in the sediment appears to provide ecological advantages our survey of the physico chemical parameters shows an extreme variability at the surface in comparison with much more stable conditions deeper in the sediment these more stable conditions demanding smaller tolerance ranges for several parameters temperature salinity water content appear to be advantageous to deep infaunal taxa for the species j macrescens the microhabitat depth appears to be controlled by the water content of the sediment that strongly fluctuates in function of the meteorological conditions during dry periods when the water content of the sediment is lower j macrescens displays a much shallower microhabitat than during more humid periods at the sediment surface the presence of vegetation appears to have a positive influence on the density of the foraminiferal faunas by providing a shelter to desiccation during low tide or more prolonged dry periods important differences exist between the live faunas found in the uppermost centimetre of the sediment and those of the total 9 cm deep sediment cores therefore data inventories of living faunas based on the superficial centimetre alone can not be used as a basis for paleo environmental reconstructions without correction for these microhabitat effects

holocene delta evolution and sediment discharge of the mekong river southern vietnam abstract evolutionary changes delta progradation and sediment discharge of the mekong river delta southern vietnam during the late holocene are presented based on detailed analyses of samples from six boreholes on the lower delta plain sedimentological and chronostratigraphic analyses indicate clearly that the last 3 kyr were characterized by delta progradation under increasing wave influence southeastward sediment dispersal decreasing progradation rates beach ridge formation and steepening of the face of the delta front estimated sediment discharge of the mekong river for the last 3 kyr based on sediment volume analysis was 144 36 million t yr 1 on average or almost the same as the present level the constant rate of delta front migration and stable sediment discharge during the last 3 kyr indicate that a dramatic increase in sediment discharge owing to human activities as has been suggested for the yellow river watershed did not occur although southeast asian rivers have been considered candidates for such dramatic increases in discharge during the last 2 kyr the mekong river example although it is a typical large river of this region does not support this hypothesis therefore estimates of the millennial scale global pristine sediment flux to the oceans must be revised

marine incursions of the past 1500 years and evidence of tsunamis at suijin numa a coastal lake facing the japan trench sandy deposits of marine origin underlie the floor of suijin numa a coastal lake midway along the subduction zone marked by the japan trench the deposits form three units that are interbedded with lacustrine peat and mud above a foundation of marine probably littoral sand unlike the lacustrine deposits all three sandy units contain marine and brackish diatoms the middle unit b contains in addition graded beds sug gestive of multiple waves of long wavelength and period the uppermost unit c probably dates to a time in the area s written history when the lake was separated from the sea by a beach ridge plain at least 0 5 km wide and several metres high units a and b postdate ad 540 870 and unit c postdates ad 1030 1640 as judged from radiocarbon dating of leaves and seeds unit b pre dates ad 915 and unit c postdates that year as judged from a tephra within the peat that separates units b and c the age constraints permit correlation of unit b with a tsunami in ad 869 that reportedly devastated at least 100 km of coast approximately centred on sendai unit c may represent a later catastrophic tsunami in 1611 or perhaps a storm surge that inundated much of sendai the lake lacks obvious signs of tsunamis from the region s largest twentieth century earthquakes which were centred to the north in 1933 m 8 1 and directly offshore in 1936 m 7 5 and 1978 mw 7 6

a high resolution simulation of the ocean during the pomme experiment simulation results and comparison with observations 1 a modeling study of physical processes occurring in an area of the northeast atlantic 21 33 15 33 w 38 00 45 00 n that was extensively sampled during the programme ocean multidisciplinaire meso echelle pomme october 2000 september 2001 is carried out the model is a mesoscale version of the ocean general circulation model opa developed at the laboratoire d oceanographie dynamique et de climatologie in paris it is used in a three dimensional limited area domain with a high resolution grid approximately 5 km horizontal spacing 69 vertical levels and realistic boundary conditions initial state air sea fluxes open boundary fluxes and bottom topography the objectives of the study are to properly simulate the upper ocean dynamics particularly mesoscale activity and mixed layer evolution during a key period restratification of the pomme experiment pomme 1 and pomme 2 from february to may 2001 and to compare model results with oceanographic observations collected during the experiment in order to establish confidence in the model some results provided by the high resolution simulation in particular features related to mixed layer depth and vertical velocities are also presented there is no pronounced north south mixed layer depth gradient but strong filament shaped structures associated with stirring at the periphery of eddies are present mixed layer restratification is simulated it is associated with submesoscale mixed layer depth structures and intense vertical velocity filaments in the upper ocean correlated with the relative vorticity gradient field

distribution of rare earth elements in eastern kentucky coals indicators of multiple modes of enrichment abstract four eastern kentucky pennsylvanian coals from oldest to youngest the manchester pond creek fire clay and hazard coals were examined for their total rare earth element rey concentration and the possible mechanisms for enrichment of the rare earths based on previous studies four possible modes are considered terrigenous tuffaceous infiltrational and hydrothermal with the dean coal a correlative of the fire clay coal considered to be a typical example of the tuffaceous mode the fire clay owes much of its high rey content to the presence of a volcanic ash fall tonstein with rey bearing zircon and phosphates in the coal in numerous locations some of the original rey elements may have components of the detrital minerals deposited in the peat leaching of rey from the tonstein into the surrounding coal and the hydrothermal overprint of mineralizing fluids associated with the northwestwardly movement of the pine mountain thrust sheet contributed to the total rey signature in the fire clay coal not all coals are going to have the complex history of the fire clay coal but it should be considered that the total history of rey enrichment by multiple mechanisms is what gives us both the total rey concentration and the relative distribution of the individual lanthanide elements

hurricane induced sediment deposition in a gulf coast marsh abstract rates of sediment accumulation in four coastal marsh communities in the mississippi river deltaic plain louisiana were studied using feldspar clay marker horizons the results indicate that normal riverine flooding contributes relatively little

heightened hurricane surge risk in northwest florida revealed from climatological hydrodynamic modeling and paleorecord reconstruction historical tropical cyclone tc and storm surge records are often too limited to quantify the risk to local populations paleohurricane sediment records uncover long term tc activity but interpreting these records can be difficult and can introduce significant uncertainties here we compare and combine climatological hydrodynamic modeling including a method to account for storm size uncertainty historical observations and paleohurricane records to investigate local surge risk using apalachee bay in northwest florida as an example the modeling reveals relatively high risk with 100 year 500 year and worst case surges estimated to be about 6 3 m 8 3 m and 11 3 m respectively at bald point a paleorecord site and about 7 4 m 9 7 m and 13 3 m respectively at st marks the head of the bay supporting the inference from paleorecords that apalachee bay has frequently suffered severe inundation for thousands of years both the synthetic database and paleorecords contain a much higher frequency of extreme events than the historical record the mean return period of surges greater than 5 m is about 40 years based on synthetic modeling and paleoreconstruction whereas it is about 400 years based on historical storm analysis apalachee bay surge risk is determined by storms of broad characteristics varies spatially over the area and is affected by coastally trapped kelvin waves all of which are important features to consider when accessing the risk and interpreting paleohurricane records in particular neglecting size uncertainty may induce great underestimation in surge risk as the size distribution is positively skewed while the most extreme surges were generated by the uppermost storm intensities medium intensity storms categories 1 3 can produce large to extreme surges due to their larger inner core sizes for apalachee bay the storms that induced localized barrier breaching and limited sediment transport overwash regime surge between 3 and 5 m are most likely to be category 2 or 3 storms and the storms that inundated the entire barrier and deposited significantly more coarse materials inundation regime surge 5 m are most likely to be category 3 or 4 storms

detrital clay grain coats in estuarine clastic deposits origin and spatial distribution within a modern sedimentary system the gironde estuary south west france

wave control on the rhythmic development of a wide estuary mouth sandbank a process based modelling study abstract this study presents the numerical hindcast of the morphological and stratigraphic evolution of a wide estuary mouth sandbank located along the french atlantic coast marennes oleron bay and primarily investigates the respective contribution of tide and waves to its pluri decadal evolution firstly the morphodynamic hindcast appears strongly improved when tide and waves are considered in the forcing rather than only tide secondly the modelling results suggest that the strong seasonal variation of the wave climate in this area explains the rhythmic lateral accretion of the bank i e normal to the main currents direction observed in seismic reflection profiles the grain size variation in the area of sediment accretion is also characterized by a seasonal cycle finally repetitive bathymetric surveys and seismic profiles revealed that the lateral accretion of the bank is associated with about one seismic reflector per year which is in agreement with our modelling results when assuming that these seismic reflectors are due to the seasonal variation of the grain size these new results may be considered when studying the morphological evolution and the stratigraphy of other tidal sandbanks potentially affected by waves

rare earth minerals in a no tonstein section of the dean fire clay coal knox county kentucky abstract the dean fire clay coal in knox county kentucky does not contain the megascopically visible ash fall tonstein present in most other sections of the coal bed like the fire clay tonstein a low ash portion of the coal is enriched in rare earth elements 2400 ppm on ash basis in addition to kaolinite produced in the diagenesis of volcanic glass transmission electron microscopy studies indicate the coal contains primary kaolinite la ce nd th monazite barium niobate native gold and fe ni cr spinels the mineral assemblages particularly the kaolinite monazite association and its similarity to the tonsteins in coal to the east demonstrate the coal was subject to the ree enriched volcanic ash fall apparently just at a more dilute level than at locations where the tonstein is present

petrology of the pond creek coal bed in eastern kentucky abstract the middle pennsylvanian breathitt formation pond creek coal bed was examined along two cross sections in pike and martin countries in the eastern kentucky coal field along the north south profile the sulfur content increased markedly to the top of the bed in the eastern portion of the east west profile the coal bed is marked by a high vitrinite high ash bone shaley coal lithotype within the top half of the bed and by a thin clarodurite vitrinertoliptite rich durain at the top of the bed a northeastward plunging anticline termed here the belfry anticline marks the boundary between the high sulfur coal beds in the west and the appearance of the bony horizon on the east the coal and the interval between the rider and the coal bed both thin across the anticline which was active at the time of deposition

a modeling based analysis of the flooding associated with xynthia central bay of biscay storm induced coastal flooding is among the most destructive natural disasters as seen recently in the bay of bengal the gulf of mexico and the philippines this study presents a high resolution hindcast of the flooding associated with xynthia a mid latitude storm that severely hit the central part of the bay of biscay in february 2010 a 2dh fully coupled modeling system is applied to the north east atlantic ocean with a resolution locally reaching a few meters along the coastline of the study area such a fine resolution was required to adequately represent the dikes and the barriers that usually prevent the area from flooding but results in a 1 700 000 element unstructured grid the comparison with the available data reveals that waves and water levels are reproduced with normalized errors of the order of 10 and 5 respectively the extension of the flooding is also well reproduced although with some underestimations along the coastline and overestimation in the inner part of large marshes these limitations are explained by a lack of spatial resolution locally and the absence of several processes in the model such as infragravity waves and wave runup the comparison between our baseline simulation and a simulation where the flooding is disabled by increasing the dike height reveals differences in maximum water levels locally reaching 1 0 m this result is of key importance for coastal management strategies and also questions classical engineering approaches relying on one way nesting

decadal buoyancy forcing in a simple model of the subtropical gyre the decadal response of the ventilated thermocline to surface buoyancy forcing is investigated using simplified mixed layer thermodynamics and two layer planetary geostrophic dynamics the model is forced by a stationary ekman pumping and a fluctuating sea surface density while the associated surface buoyancy flux is diagnosed from the buoyancy budget of ventilated columns the decadal forcing is represented as a slow modulation of the seasonal cycle rather than a slow periodic forcing as in liu and pedlosky it is found that the amplitude and the degree of nonlinearity of the interior response depend on the anomalies of the yearly averaged surface buoyancy flux but that omitting the seasonal cycle leads to an overestimation of the thermocline variability by a factor of 2 at periods longer than 10 years the interior response becomes linear and frequency independent so that in the presence of stochastic buoyancy forcing the spectrum of potential vorticity or interface displacement is white at low frequency and red at high frequency a statistical signature of the buoyancy forcing is the asymmetric shape of the cross covariance function between sea surface density and interface displacement anomalies in lead and lag conditions

stratigraphical evidence of late holocene barrier breaching and extreme storms in lagoonal sediments of ria formosa algarve portugal stratigraphical sedimentological and paleoecological studies undertaken in lagoonal sediments of the ria formosa barrier lagoon indicate that a number of present day aligned beaches outcropping within the marsh and detached from mainland marsh detached beaches mdb represent the remnants of former ephemeral flood deltas which established following barrier breaching induced by extreme storms from circa 1270 bc onwards dating of these beaches suggests that they resulted from multiple events of flooding separated both in time and space repeated emplacement of tidal deltas following overwash of the same location of the barrier is represented in the stratigraphical record by buried and partly overlapping marsh beaches it is suggested that further refinement of the data presented in this paper and the extension of the stratigraphic survey to the entire lagoonal space will substantiate the usefulness of the stratigraphic record as a proxy to hindcast a time series of extreme storminess extending far beyond the instrumental and historical records

sedimentary records of past earthquakes in boraboy lake during the last ca 600 years north anatolian fault turkey abstract multiproxy sedimentological analyses along 4 9 m long sequence of boraboy lake which is located on the central eastern part of the north anatolian fault naf reveal the sedimentary traces of past large earthquakes in the region the lake has a relatively large catchment area 10 km2 compared to its size 0 12 km2 which renders sedimentation sensitive to heavy rain storm events accordingly the background sedimentation which is composed of faintly laminated reddish yellowish brown clayey silt is frequently interrupted by organic rich intercalations probably due to heavy rain storm events transporting terrestrial plant remains from the densely vegetated catchment in addition to frequent organic rich intercalations the background sedimentation is interrupted by four mass wasting deposits mwd of which thickness range is between 15 and 50 cm high resolution itrax xrf data confirms higher homogeneity along the mwds e1 e4 compared to the background sedimentation based on 137cs and 210pbxs dating and radiocarbon chronology three mwds detected in boraboy sequence e2 e3 and e4 temporally correlate with large historical earthquakes along the naf the 1943 tosya ms 7 6 and or 1942 niksar erbaa ms 7 1 the 1776 amasya merzifon and the 1668 north anatolian ms 7 9 earthquakes the youngest mwd in the sequence e1 which is dated to early 2000s does not correlate with any strong earthquake in the region this mwd was probably a single mass wasting event due to routine overloading and oversteepening on the delta front formed by the main inlet of the lake in subaqueous paleoseismology coevality of multi location mass wasting events is used as a criterion to assign a seismic triggering mechanism and to rule out mass wasting events due to routine overloading oversteepening of subaqueous slopes within this context boraboy sequence provides a valuable example to discuss sedimentological imprints of single vs multi source mwds

architecture and long term evolution of a tidal sandbank the middelkerke bank southern north sea abstract the internal structure of the middelkerke bank one of the flemish banks located in the southern north sea off the coast of oostende belgium has been studied in the framework of the marine science and technology mast program co funded by the european community a dense grid of high and very high resolution seismic profiles has been used as well as several vibrocorings seven major seismic units can be identified in the quaternary sediments bounded by major discontinuities correlated across the whole study area the lower units clearly appear as being deposited during periods of relative low sea level channel infillings shoreface estuarine and or ebb tidal delta deposits the present shape of the bank results partly from recent erosional processes reworking the underlying deposits thus the lower part of the bank as a morphological feature does not consist of offshore tidal sands the master bedding of the upper part of the bank consists of inclined reflectors dipping at an angle of about 5 in the same direction as the bank s steep face these reflectors very similar to those described by houbolt 1968 are interpreted as being the result of alternating periods of deposition and erosion related to the episodic combination of tidal currents and storms

influence of regional structure on the development and quality of the upper elkhorn no 2 coal bed eastern kentucky abstract the upper elkhorn no 2 coal bed middle pennsylvanian breathitt formation in eastern kentucky exhibits thickness and coal quality trends which suggest that peat deposition was contemporaneous with tectonism the coal thickens and has high vitrinite and low ash and sulfur content the belfry anticline in pike country t in the vicinity of the floyd country channel a basement trough in both cases other pennsylvanian coals exhibit similar trends suggesting that the penecontemporaneous tectonism persisted at least through a portion of the carboniferous

multi time scale evolution of a wide estuary linear sandbank the longe de boyard on the french atlantic coast abstract this trans disciplinary work combines modeling and observational approaches and offers a unique dataset to study the behaviour of a wide estuary linear sandbank over different time scales the sandbank studied the longe de boyard lies in a macrotidal estuary environment off the french atlantic coast side scan sonar data combined with shipek grab samples and numerical modeling of waves and tides revealed its short term dynamics historical 1824 and present day 2000 and 2003 bathymetric data combined with numerical simulations of waves and tides and tide related sand transport in 1824 and seismic profiling were then used to demonstrate the long term evolution of the sandbank and how this correlates with the short term dynamics the geological evolution centuries to millennia was finally deduced from seismic stratigraphy combined with an analysis of vibrocore samples most of the long term morphological changes in the longe de boyard can be explained by the short term dynamics involving sand transport convergence driven by both tides and waves seaward the changes in the axial part of the bank correspond mainly to erosion and can be explained by wave and tide ravinment shoreward sediment accretion is related to the convergence of tide related sand transport during ebb and flood due to the dam effect of the crest of the bank the changes in the sandbank since 1824 can also be related to a decrease in the tidal channel cross section the latter was the result of a 10 decrease in tidal currents and tidal prisms subsequent to the rapid sediment infill and a related 20 reduction in the water volume of the estuary system where the sandbank lies seismic stratigraphy and cores showed that the modern sandbank consists of upper clinoforms made of fine sand built up over a core made of coarse sand and gravel related to high energy environments hence the longe de boyard is not only the result of sand convergence driven by both tides and waves but also integrates decreases in the tidal prism subsequent to sediment infilling of the surrounding estuaries on a century and millenia time scale

lithologic succession in the path fork coal bed breathitt formation middle pennsylvanian southeastern kentucky abstract the path fork coal bed breathitt formation middle pennsylvanian westphalian b on the pine mountain thrust sheet in southeastern kentucky and adjacent portions of virginia exhibits a lithologic succession which is traceable for about 25 km lateral continuity of lithotypes within the bed can be demonstrated using organic petrography palynology and ash geochemistry the lithologic continuity is a consequence of the initial levelling of the pre peat topography and the interaction of the peat with growing anticlines and synclines

habitat characterization of deep water coral reefs in la gaviera canyon aviles canyon system cantabrian sea abstract surveys conducted at the complex aviles canyon system southern bay of biscay in order to identify vulnerable habitats and biological communities revealed the presence of noteworthy deep water coral reefs in one of the tributaries of the system la gaviera canyon the aim of the present study is to determine why this deep sea canyon provides suitable environmental conditions for corals to grow this hanging canyon is characterized by an irregular u shaped floor with two narrow differentiated flanks sand ripples and rocky outcrops structured in diverse w e directed steps are observed on the canyon floor suggesting intense hydrodynamic activity accordingly high frequency near bottom current and thermal structure profiles showed that there occur strong shifts in currents hydrography behaving as front like features at each tidal cycle these involve the sudden increase of along axis velocities to over 50 cm s and vertical velocities of over 5 cm s in each tidal cycle associated with the passage of sharp thermal fronts and thermal inversions suggesting overturning a year long near bottom current record showed events with near bottom velocities well over 1 m s lasting for several days three cold water coral settings were distinguished a dense coral reef located on stepped rocky bottoms of the eastern and western flanks carbonate mounds 20 30 m high located on the canyon floor and a cluster of shallower water dead coral framework at the head sector of the canyon video and still images from a towed sled and rov verified the presence of dropstones and rippled sand sheets surrounding the mounds and revealed changes in the coral population alive or dead total or patchy coverage in coral reef and carbonate mound areas the dominant species of the reef are lophelia pertusa and madrepora oculata which considerably increase the habitat s complexity and biodiversity in relation to other facies described in the canyon the presence of living cold water reefs is directly related to a high energy environment at depths between 700 and 1200 m in the levels between the lower bound of eastern north atlantic central water enacw and the core of mediterranean water mw such level matches the water density range 27 35 27 65 kg m 3 which has been identified as limits for cold water coral distribution in the north atlantic

diagnosing natural variability of north atlantic water masses in hadcm3 abstract a study of thermally driven water mass transformations over 100 yr in the ocean component of the third hadley centre coupled ocean atmosphere general circulation model hadcm3 is presented the processes of surface forced transformations subduction and mixing both above and below the winter mixed layer base are quantified subtropical mode waters are formed by surface heat fluxes and subducted at more or less the same rate however labrador seawater and nordic seawater classes the other main subduction classes are primarily formed by mixing within the mixed layer with very little formation directly from surface heat fluxes the subpolar mode water classes are dominated by net obduction of water back into the mixed layer from below subtropical mode water 18 c variability shows a cycle of formation by surface fluxes subduction 2 yr later followed by mixing with warmer waters below the winter mixed layer base during the next 3 yr and finally obduction back into the mixed layer at 21 c

subaqueous delta of the ganges brahmaputra river system abstract the ganges brahmaputra is among the world s three largest river systems in terms of sediment load but until now no high resolution seismic data have been obtained to document the nature of the sediment deposit seaward of the rivers mouths the other two amazon huanghe discharge into energetic coastal environments and form subaqueous deltas with characteristic clinoform stratigraphy high resolution seismic reflection profiles of the bengal shelf reveal similar stratigraphy topset beds dip gently 0 036 and diverge offshore more steeply dipping foreset beds 0 190 converge farther seaward and relatively thin gently dipping bottomset beds 0 022 extend across the outer shelf overlying an erosional surface presumed to be of late pleistocene age sediment accumulation rates are highest in the foreset region 5 cm year and reduced in the bottomset region

seismic stratigraphy and morphology of the holocene progradational system beneath bohai bay bohai sea lobate evolution of a multi sourced subaqueous fluviodeltaic complex abstract since 6 kyr bp the subaerial deltas of the yellow the yanshan and the taihang river systems evolved along the bohai bay coast forming several lobate progradational systems associated with frequent avulsions of these river systems their subaqueous parts consist of a multi sourced subaqueous deltaic complex in bohai bay but little is known about the complex s subsurface structure morphology and evolutionary history here we investigate these characteristics using a dense high resolution seismic survey using stratigraphic superposition seismic geometry and the results of previous studies we identified nine seismic units sus in the post last glacial maximum stratigraphy which are interpreted from bottom to top as 1 fluvial lacustrine sediments su0 2 marine sands combined with estuarine coastal deposits su1 and 3 a subaqueous fluviodeltaic complex sus2 8 these units correspond to the lowstand system tract the transgressive and or highstand system tracts and the normal regressive system tract respectively and evolved as a function of eustatic fluctuations the subaqueous fluviodeltaic complex is characterized by a discrete and spatially confined lobate architecture which is indicative of step wise switching of subaqueous lobes two sets of progradational systems ps a northern one sus2 3 and a southern one sus4 8 were observed within the complex tapering in opposite directions and bounded by an erosional unconformity r3 these characteristics indicate that the two ps were sourced from different river systems and prograded at different times r3 forms the base of the southern ps but cross cuts the northern ps indicating that it is a diachronous surface marks the preexisting seafloor which was further reworked eroded by the progradation of the southern ps in each ps the internal subaqueous lobes correlated well with the onshore lobes superlobes of the subaerial deltas suggesting the lobate evolution of the complex is driven predominantly by alternating erosion and deposition caused by the variation in fluvial supply which appears to be linked to the frequent avulsions of the major river systems in addition to the multi sourced supply based on the dipping geometries and the locations of the depocenters we hypothesize that 1 the northern ps is the seaward extension of the ancient haihe river s northern branch 2 the bulk of southern ps in the middle and southern bohai bay is correlated with the principal body of the yellow river subaqueous delta 3 the majority of the volume of the northern ps in northern bohai bay consists of the modern haihe river subaqueous delta

facies and architecture of an estuarine tidal bar the trompeloup bar gironde estuary sw france abstract this study describes the sedimentary facies and internal architecture of a modern estuarine tidal bar present in the bay head delta of a wave and tide dominated estuary the gironde estuary in southwest france based on 51 cores 2 to 5 m long this work demonstrates that such bars are composite sedimentary bodies made up of individual sigmoidal sand units isolated from one another by thick muddy layers the bar appeared in the study area around 1874 since then its evolution has been characterized by phases of rapid downstream bar migration alternating with periods of bar abandonment during the periods of active bar progradation which commonly last between 10 and 20 years the bar progrades up to 7 km seaward and forms a narrow 200 800 m wide sand ridge up to 6 m thick during abandonment phases which also last around 10 20 years the bar is starved of sand and a mud layer 1 to 3 m thick is deposited the vertical succession formed by the seaward progradation of the tidal bar records these alternating phases of growth and abandonment a typical vertical succession in the bar system is 8 m thick and comprises several superimposed upward coarsening units of cross stratified sand deposited during phases of seaward progradation separated by a thick layer of thinner bedded mud and sand laminae deposited during phases of bar abandonment when a tidal bar builds up to the supratidal zone marshes accumulate and the bar becomes a permanent island in the estuary the large scale architecture of the bar is thus made of an alternation of potential sandy reservoir units and muddy internal seals the reservoir units are characterized by a sigmoidal shape the muddy layer which is deposited between the two sigmoidal units is a thick continuous potential internal seal this complex internal architecture is due to the fact that there is a considerable amount of mud present in the bay head delta of the gironde estuary it is thought to be representative of the architecture of tidal bars in the inner part of wave and tide dominated estuaries

tidal and fluvial controls on the internal architecture and sedimentary facies of a lobate estuarine tidal bar the plassac tidal bar in the gironde estuary france abstract estuarine tidal bars emplaced in estuaries are complex sediment bodies composed of sand and mud provided by rivers this study focuses on the plassac tidal bar which is the unique lobate shape tidal bar of the gironde estuary located at the very upstream extremity of the bay head delta because no detailed sedimentological studies have been made on such geomorphological category of tidal bar its stratigraphy was investigated using a dense grid of 65 very high resolution seismic profiles ground truthed by 6 to 9 meter long cores and time controlled by historical bathymetric surveys the base of the tidal bar consists of a tidal erosional surface this surface has eroded muddy tidalites corresponding to the maximum flooding surface of the gironde estuary the bar is composed of two vertical sequences of facies composed of thickening up cross stratified fine to medium grained sand beds at the top and decimeter thick mud layers at the base those mud layers constitute the master bedding of the bar and are dipping in a channelward direction perpendicularly to the tidal flows and to the sediment transport directions one phase of lateral accretion of the plassac tidal bar is correlated with variations in fluvial discharge of the last decades and suggests a climate control on the internal architecture of this sandbar low water periods lead to the upstream migration of the turbidity maximum and to the deposition and consolidation of the muddy master bedding planes during the subsequent flood periods the muddy master bedding planes are partially eroded and then buried by the fluvially sourced sandy mini flood lobes that merge with the tidal bar the internal architecture of the plassac tidal bar is controlled by a lateral accretion process its master bedding surfaces which record this process are dipping perpendicularly to the axis of the tidal flows all the other tidal bars of the bay head delta around a dozen exhibit an elongated morphology and prograde longitudinally by seaward frontal accretion occurring in the axis of the tidal flows the master bedding surfaces which record this process are seaward dipping along the axis of the tidal flows those variations in internal accretion surfaces orientation of tidal bars are of considerable importance and must be taken into account for studies of ancient tidal deposits paleoenvironment reconstructions and for heterogeneities characterization and quantification of reservoir properties in these types of sandstones

ostracodes reveal the sea bed origin of tsunami deposits 1 in rikuzentakata city ostracode assemblages in sediment deposited by the tohoku oki earthquake and tsunami of 11 march 2011 revealed that the sediment was derived from the seafloor from at least 9 m water depth and was transported inland more than 1 km the tsunami wave height at this location was higher than 10 m four hundred fifty seven modern ostracode assemblages were used in the modern analogue technique to estimate the depth source of the tsunami deposited assemblages the application of this method to paleo tsunami deposits may provide insight into past tsunami wave height and potentially earthquake slip and magnitude

eastern north atlantic mode waters during pomme september 2000 2001 four hydrographic surveys in the northeast atlantic 38 45 n 15 21 w carried out during the programme ocean multidisciplinaire meso echelle pomme experiment september 2000 2001 are used to investigate the water masses in the upper layers corresponding to eastern north atlantic mode waters a large meridional gradient in isopycnal temperature salinity is witnessed which has no counterpart in climatology and is associated with an anomalous eastward current near 41 n waters tend to be warmer more salty somewhat more stratified and less oxygenated on isopycnal surfaces in the southern part of the domain in addition there is an overlying zonal gradient of properties in particular north of the jet consistent with earlier descriptions however these large scale distributions also change significantly through the pomme year in particular between the february and early april surveys which we attribute to 1 the arrival of a 2001 vintage of mode waters in particular in the northeastern part of the domain and to 2 stirring by the mesoscale motions which contribute to down gradient transport equivalent diffusion coefficient of 2000 m 2 s for s 27 10 on a smaller scale there are noticeable changes in properties between surveys some of which can be shown by quasi lagrangian diagnostics to result from advection by the horizontal circulation in particular in the southwest corner of the domain between the surveys p1 february 2001 and p2 april 2001 horizontal isopycnal advection is responsible for a large cooling freshening and oxygen increase or in the northeast corner where new oxygenated and freshly ventilated water in particular for surface s q 27 05 kg m 3 penetrates during that period in other regions or for a longer period water masses are often difficult to track as a result of dispersion or stirring by the eddies and too small of a pomme domain

lake sediment record of late holocene hurricane activities from coastal alabama coastal lake sediments contain a stratigraphically and chronologically distinct record of major hurricane strikes during late holocene time frederic a category 3 hurricane that struck the alabama coast on the gulf of mexico in 1979 left a distinct sand layer in the nearshore sediments of lake shelby as a result of storm tide overwash of beaches and dunes sediment cores taken from the center of lake shelby contain multiple sand layers suggesting that major hurricanes of category 4 or 5 intensity directly struck the alabama coast at ca 3 2 3 0 2 6 2 2 1 4 and 0 8 ka 14 c yr with an average recurrence interval of 600 yr the alabama coast is likely to be struck by a category 4 or 5 hurricane within the next century

nummulitic banks in the upper lutetian buil level ainsa basin south central pyrenean zone the impact of internal waves nummulites a particularly abundant and diverse genus of larger benthonic foraminifera formed huge accumulations banks during the eocene which are often good hydrocarbon reservoirs especially in north africa despite their economical interest these accumulations are not well understood and their origin is still under discussion reasons for this debate are the absence of living nummulites accumulations and the high variability of facies including the size shape and extension of the banks which reflect the array of processes controlling sediment production and accumulation the nummulitic banks near santa maria de buil in the ainsa basin south pyrenean foreland basin are composed of recurrent facies associations within mappable bed units bounded by physical surfaces the depositional processes that produced the nummulites deshayesi accumulations are interpreted considering the shape of the banks the type of bounding surfaces the distribution of sedimentary textures nummulites test shapes and the associated skeletal components within the banks this integrative analysis indicates that nummulitic banks accumulated from mass flows with very poor sediment sorting textural and compositional differences among banks suggest that globose nummulites thrived in the shallower part of the mesophotic zone with abundant nummulithoclasts whereas flat nummulitic forms thrived in deeper mesophotic clay dominated settings interbedded with nummulitic banks coral biostromes and coral mounds bearing operculina discocyclina and asterocyclina represent in situ accumulation near the base of the photic zone internal waves waves that propagate along the pycnocline are thought to be the triggering mechanism for the density flows internal waves and induced bottom currents are sporadic but strong enough to bring sediments into suspension in contrast to surface waves both fair weather and storm whose impact is strongest near the sea surface and decreases with bathymetry the impact of internal waves is usually strongest in the mid shelf region and weaker in shallow water this explains the compositional character of the nummulitic banks

pleistocene forced regressions and tidal sand ridges in the east china sea abstract tidal sand ridges are common features on modern shelves but only few examples of such preserved sand bodies are described in pleistocene deposits in the stratigraphic record some sand bodies encased in shales previously interpreted as sand ridges have been reinterpreted as shoreface deposits more than 5000 km of high resolution seismic data from the east china sea correlated to geotechnical boreholes and shallow cores demonstrate the potential of sand ridge preservation and allow reconstruction of the depositional history of pleistocene fourth order 100 kyr depositional sequences a high subsidence rate of about 300 m myr allows the preservation of three elementary sedimentary facies constitutive of a motif which was repeated during glacio eustatic cycles they consist of 1 regressive marine prodeltaic prograding wedges 2 estuarine and continental deltaic facies and 3 transgressive sand ridges similar in shape and orientation to modern sand ridges major discontinuities traceable over the entire outer continental shelf along distances of hundreds of kilometers are transgressive and regressive surfaces of marine erosion whereas sequence boundaries formed by fluvial erosion are difficult to identify on this low gradient shelf because of the asymmetry of the pleistocene glacio eustatic cycles most of the preserved sedimentary record with the exception of sand ridges corresponds to forced regressive deposits deposits that formed during a seaward shift of the shoreline due to relative sea level lowering

changing patterns of pennsylvanian coal swamp vegetation and implications of climatic control on coal occurrence abstract improved regional and interregional stratigraphic correlations of pennsylvanian strata permit comparisons of vegetational changes in euramerican coal swamps the coal swamp vegetation is known directly from in situ coal ball peat deposits from more than 65 coals in the united states and europe interpretations of coal swamp floras on the basis of coal ball peat studies are extended to broader regional and stratigraphic patterns by use of coal palynology objectives of the quantitative analyses of the vegetation in relation to coal are to determine the botanical constituents at the peat stage and their environmental implications for plant growth and peat accumulation morphological and paleoecological analyses provide a basis for deducing freshwater regimes of coal swamps changes in composition of pennsylvanian coal swamp vegetation are quire similar from one paralic coal region to another and show synchrony that is attributable to climate paleobotany and paleogeography of the euramerican province indicate a moist tropical paleoclimate rainfall runoff and evapotranspiration were the variable climatic controls in the distribution of coal swamp vegetation peat accumulation and coal resources in relative terms of climatic wetness the pennsylvanian period is divisible into five intervals which include two relatively drier intervals that developed during the lower middle and middle upper pennsylvanian transitions the climate during early pennsylvanian time was moderately wet and the median in moisture availability early middle pennsylvanian was drier probably seasonally dry wet late middle pennsylvanian was the wettest in the midcontinent early late pennsylvanian was the driest and late late pennsylvanian was probably the wettest in the dunkard basin the five climatic intervals represent a general means of dividing coal resources within each region into groups with similar botanical constituents and environments of peat accumulation regional differences in basinal geology and climate were significant variables but the synchronous control of paleoclimate was of primary importance

central water vortices of the eastern north atlantic abstract a set of 102 high resolution hydrographic lines mostly xbt lines in the eastern north atlantic is used to study baroclinic vortices dynamically intensified within the central water layer first for the sake of comparison with recent results from altimetry spatial statistics of the main thermocline dynamic height are computed the dynamic height wavenumber spectrum slope close to k 3 at wavelengths shorter than 300 km and the decrease with latitude of eddy scales deduced from its autocorrelation function are found to be consistent with previous local altimetric results then using a criterion of local temperature anomaly relative to the large scale trend along each line 162 central water mesoscale vortices are detected their distribution is heterogeneous vortices of different size sign and intensity being found in most places they have a mean apparent diameter chord along the line of 110 50 km it is estimated that a range of 100 145 central water vortices coexist at the same t

vertical particle flux in the northeast atlantic ocean pomme experiment 1 in the framework of the programme ocean multidisciplinaire meso echelle pomme experiment a 1 5 year record february 2001 june 2002 of downward particle flux at 400 m and 1000 m was measured by sediment traps at four moorings located in the northeast atlantic between 39 43 n and 17 19 w thorium 230 was used to estimate sediment trap efficiency revealing values ranging from 18 5 to 55 the lowest trapping efficiency was observed for the trap having experienced the highest currents significant interannual variability between 2001 and 2002 was clearly linked to the differences observed in the mixed layer depth at some sites particulate organic carbon poc export was higher up to a factor of 1 6 during summer than during the spring event this could be related to the occurrence of short wind events that deepened the thermocline along with the presence of anticyclonic eddies yielding an input of new nutrients the average percentage of poc exported compared to the primary production of organic carbon in the surface waters ranged between 1 3 and 5 0 with higher export efficiency during the spring finally although the area was shown to present a relatively high mesoscale activity that might impact the geochemistry poc export was rather homogeneous over the pomme area 4 9 1 6 gc m 2 yr 1 were exported below 1000 m between february 2001 and february 2002 therefore a large fraction of the new production may be exported through convection and mode water circulation rather than by particle settling

airborne electromagnetic imaging of discontinuous permafrost 1 the evolution of permafrost in cold regions is inextricably connected to hydrogeologic processes climate and ecosystems permafrost thawing has been linked to changes in wetland and lake areas alteration of the groundwater contribution to streamflow carbon release and increased fire frequency but detailed knowledge about the dynamic state of permafrost in relation to surface and groundwater systems remains an enigma here we present the results of a pioneering 1 800 line kilometer airborne electromagnetic survey that shows sediments deposited over the past 4 million years and the configuration of permafrost to depths of 100 meters in the yukon flats area near fort yukon alaska the yukon flats is near the boundary between continuous permafrost to the north and discontinuous permafrost to the south making it an important location for examining permafrost dynamics our results not only provide a detailed snapshot of the present day configuration of permafrost but they also expose previously unseen details about potential surface groundwater connections and the thermal legacy of surface water features that has been recorded in the permafrost over the past 1 000 years this work will be a critical baseline for future permafrost studies aimed at exploring the connections between hydrogeologic climatic and ecological processes and has significant implications for the stewardship of arctic environments

lowstand deltas in the frontier formation powder river basin wyoming implications for sequence stratigraphic models deposits of lowstand deltas formed on the floor of the cretaceous interior seaway of north america are found in the cenomanian lower belle fourche member of the frontier formation central wyoming sandstones located in similar distal basin locations hundreds of kilometers basinward of highstand shoreline deposits form important hydrocarbon reservoirs isolated within marine shales but interpretation of their origin has been highly controversial the distribution geometry and internal facies of these sandstones are documented by an extensive outcrop study and regional subsurface correlations to develop genetic facies models for these deposits this integrated record of lithofacies ichnofacies palynofacies paleocurrent data bedding relationships and isolith maps incorporates observations from nearly 100 measured outcrop sections and about 550 subsurface well logs four episodes of sediment progradation and subsequent transgression each left behind gradually upward coarsening deltaic sandstones that have eroded tops these deltaic sandstones have a lobate to elongate geometry basinward dipping internal clinoform bedding radiating paleocurrents a low to moderate degree of shallow marine burrowing and show variable wave influence and tidal influence on deposition delta plain paralic and nonmarine facies have been eroded from the top of deltaic successions erosion surfaces capping progradational deltaic successions are the only stratal discontinuities that can be mapped regionally and they appear to record transgressive ravinement enhanced over areas of structural uplift compared with lowstand surfaces of erosion which record the bypass of sediments basinward low accommodation during lowstands left little room for sandstones to stack vertically and successive episodes of delta progradation were offset along strike more tide influenced delta deposits formed within shoreline embayments begin page 262 defined by the topography of older wave influenced delta lobes and subtle syndepositional deformation of the basin floor standard sequence stratigraphic terminology is difficult to use in broad lowstand systems like the frontier formation because sandstones do not show simple vertical stacking patterns major stratal discontinuities can form by processes other than lowstand fluvial erosion and minor syndepositional deformation of the basin floor exerts a first order influence on depositional and sediment preservation patterns although many basin distal sandstones have been interpreted to be deposits of offshore bars shelf isolated valley fills and stranded shorelines the frontier formation examples documented here suggest that many of these deposits may be top eroded deltas formed where rivers delivered sediment to lowstand coastlines the external geometry and internal heterogeneities of hydrocarbon reservoirs found in these types of deposits reflect processes active on the low accommodation deltaic shoreline even in cases where subsequent ravinement has significantly truncated the deposits during transgression

700 yr sedimentary record of intense hurricane landfalls in southern new england five intense category 3 or greater hurricanes occurring in 1635 1638 1815 1869 and 1938 have made landfall on the new england coast since european settlement historical records indicate that four of these hurricanes 1635 1638 1815 and 1938 and hurricane carol a strong category 2 storm in 1954 produced significant storm surges 3 m in southern rhode island storm surges of this magnitude can overtop barrier islands removing sediments from the beach and nearshore environment and depositing overwash fans across back barrier marshes lakes and lagoons in a regime of rising sea level accumulation of marsh lake or lagoon sediments on top of overwash deposits will preserve a record of overwash deposition we examined the record of overwash deposition at succotash salt marsh in east matunuck rhode island and tested the correlation with historical records of intense storms aerial photographs taken after hurricanes in 1954 and 1938 show overwash fans deposited at the site analysis of 14 sediment cores from the back barrier marsh confirmed the presence of these fans and revealed that 4 additional large scale overwash fans were deposited within the marsh sediments the four overwash fans deposited since the early seventeenth century at succotash marsh matches the historical record of significant hurricane induced storm surge these fans were most likely deposited by hurricanes in 1954 1938 1815 and either 1638 or 1635 radiocarbon dating of two prehistoric overwash fans indicated that these were deposited between a d 1295 1407 and 1404 1446 and probably represent intense hurricane strikes in the past 700 yr at least 7 intense hurricanes struck the southern rhode island coast and produced a storm surge that overtopped the barrier at succotash marsh

a late holocene record of environmental changes from coastal wetlands abel tasman national park new zealand abstract article size organic content loss on ignition loi geochemistry radiocarbon and 137cs analyses were carried out on paired cores taken from wainui totaranui and awaroa inlets abel tasman national park a 1700 year record of long and short term environmental changes was produced representing a sedimentary and geochemical sequence from tidal flat to mature salt marsh the sequence is punctuated by a series of short term environmental changes namely tsunami establishment of salt marsh and european settlement long term environmental changes include fluctuating accretion rates and relative sea level rise tsunami signatures include i a peak in fines ii contemporaneous or delayed peak in organic content and or loi iii contemporaneous peaks in fe and or s iv dilution of anthropogenic contaminants and v visible change in the sediments ruptures of the wellington and west wairarapa faults are considered to be the tsunamigenic sources pre european sediment accretion rates in abel tasman national park range from 0 5 to 1 7 mm a with post european settlement rates increasing to 1 6 2 7 mm a in the past 30 years rates have increased to 2 3 3 3 mm a the component of relative sea level rise is estimated to be about 1 3 2 2 mm a which compares favourably with the nearest tidal records from wellington

shallow pycnoclines and mode water subduction in the eastern north atlantic abstract a lagrangian one dimensional model is used to study the subduction of subpolar mode water in the eastern north atlantic and to analyze recently observed hydrological features related to this process considering a southward moving column of mode water subduction occurs when the upper part of the column starts gaining buoyancy in an annual budget the seasonal pycnocline on top of the column can no longer be completely eroded in winter and it is shown how its remnant forms a shallow secondary pycnocline at about 200 m depth which isolates the lower part of the fluid column from the atmosphere this mechanism for the subduction of subpolar mode water induces a strong meridional gradient in the winter mixed layer depth the various components of the buoyancy input are thoroughly studied horizontal advection in the shallow ekman layer and vertical advection along the column are shown to modify significantly both the thermal and haline contents of the column with magnitudes comparable to the ai

evolution of some depositional models in late carboniferous rocks of the appalachian coal fields abstract models for carboniferous coal bearing strata developed early in this century and consisted of vertical columns that described commonly occurring sequences of coal beds and associated rocks these were followed by other models that expressed patterns of both vertical and lateral variation but in those as well as earlier models depositional interpretation did not extend much beyond a basic marine nonmarine dichotomy subsequently depositional processes were linked to lithic components and showed that the areal distribution of these components formed a lateral geomorphically controlled continuum ranging from alluvial plains seaward to barrier islands evaluation of this model within a tectonic setting of rapid and differential subsidence produced by growth faulting in the southern part of the appalachian coal fields has shown that while depositional processes are substantially the same as those suggested by the model the form and spatial distribution of resulting lithic components are profoundly affected by movements on contemporaneously active subsurface structures this leads to the conclusion that previous models are a product of depositional processes strongly controlled by their tectonic setting and that further attempts at model generation will require careful assessment of the relationships of lithic distribution to subsurface structures and amounts of data necessary to recognize them

on the role of the azores current in the ventilation of the north atlantic ocean three high resolution ocean circulation models of the north atlantic differing chiefly in their description of the vertical coordinate are used to examine the ventilation of the north atlantic subtropical gyre all the models produce mode waters of realistic densities in the sargasso sea and the european basin but have azores currents of differing strengths which are categorised as strong of realistic transport intermediate and weak these differences have a critical impact upon the ventilation of the gyre most importantly the strong azores current forms an effective barrier to the southward ventilation of eastern north atlantic water from the northern european basin initially driving it southwestwards into the central gyre before turning it back eastwards again in a general cyclonic circulation north of the current the intermediate and weak azores currents instead allow the southward ventilation of this water mass near the european and african coasts the situation in nature appears to be intermediate between these two cases with the azores current acting as a partial block the study also raises the possibility of the azores current forming an advective connection between the sargasso sea mode waters in the western basin and modes of similar densities found in the eastern basin on the southern side of the current although there are high levels of variability in the extent of these lighter modes in the eastern basin in nature this postulate is supported by a number of observational studies in addition the present study also provides some support for the local production of madeira mode water in the eastern basin associated with retroflecting current branches on the southern side of the azores current overall the azores current is therefore likely to have a critical impact upon the ventilation of the subtropical gyre over a large area rather than just locally affecting the potential vorticity and density structure of the upper ocean between subtropical latitudes and the northern european basin the study also contributes to an ongoing community effort to assess the realism of our current generation of ocean models