reconstructing the stratal geometry of latest eocene to oligocene sequences in new jersey resolving a patchwork distribution into a clear pattern of progradation nine latest eocene to oligocene 34 2 23 9 ma sequences were identified and dated from eight sites situated on the onshore new jersey coastal plain and nearshore region these sequences show a patchy distribution with more complete lower oligocene sections updip and more complete upper oligocene sections downdip we projected these sequences onto a dip profile and reconstructed their original thicknesses and distributions by 2 d flexural backstripping this demonstrated that depocenters migrated offshore during the oligocene indicating that the patchy distribution can be best explained by progradation of generally thin and spacially limited clinoforms over an eocene carbonate ramp during the late eocene to oligocene the new jersey passive margin underwent a major morphologic change reconstructions indicate that the margin was a relatively steeply dipping carbonate ramp 1 500 paleoslope gradient during the eocene and was transformed into a siliciclastic margin characterized by a gentler gradient of 1 1000 and prograding clinoforms by the miocene clinoform progradation probably began during the latest eocene increased sediment supply during the oligocene resulted in the further progradation of sediments across the antecedent carbonate ramp the heights of the clinoforms ranged from 20 m during the latest eocene and earliest oligocene to nearly 50 m during the late oligocene most sediment accumulated within clinoform wedges with little or no sediment being preserved behind the clinoform inflection point q 2000 elsevier science b v all rights reserved

quantification of the effects of eustasy subsidence and sediment supply on miocene sequences mid atlantic margin of the united states we use backstripping to quantify the roles of variations in global sea level eustasy subsidence and sediment supply on the development of the miocene stratigraphic record of the mid atlantic continental margin of the united states new jersey delaware and maryland eustasy is a primary infl uence on sequence patterns determining the global template of sequences i e times when sequences can be preserved and explaining similarities in miocene sequence architecture on margins throughout the world sequences can be correlated throughout the mid atlantic region with sr isotopic chronology 0 6 m y to 1 2 m y eight miocene sequences correlate regionally and can be correlated to global 18 o increases indicating glacioeustatic control this margin is dominated by passive subsidence with little evidence for active tectonic overprints except possibly in maryland during the early miocene however early miocene sequences in new jersey and delaware display a patchwork distribution that is attributable to minor tens of meters intervals of excess subsidence backstripping quantifi es that excess subsidence began in delaware at ca 21 ma and continued until 12 ma with maximum rates from ca 21 16 ma we attribute this enhanced subsidence to local fl exural response to the progradation of thick sequences offshore and adjacent to this area removing this excess subsidence in delaware yields a record that is remarkably similar to new jersey eustatic estimates we conclude that sea level rise and fall is a fi rstorder control on accommodation providing similar timing on all margins to the sequence record tectonic changes due to movement of the crust can overprint the record resulting in large gaps in the stratigraphic record smaller differences in sequences can be attributed to local fl exural loading effects particularly in regions experiencing largescale progradation

strontium isotope and sequence stratigraphy of the miocene kirkwood formation southern new jersey we use sr isotope stratigraphy to correlate the miocene kirkwood formation of the new jersey coastal plain to the geomagnetic polarity time scale gpts and to ascertain the age of miocene depositional sequences sr isotope stratigraphy confirms diatom biostratigraphy which delineates three kirkwood sequences corresponding to east coast diatom zone ecdz 1 ecdz 2 and ecdz 6 of andrews 1988 sr isotope age estimates of the lowermost sequence ecdz 1 range from 19 2 to 22 6 ma 0 5 m y the middle sequence ecdz 2 ranges from 15 5 to 17 4 ma 0 5 m y a disconformity within ecdz 2 at the belleplain state forest borehole and the wildwood 198a well separates it into two sequences with a possible hiatus from 17 to 16 ma sr isotope age estimates of the upper kirkwood sequence ecdz 6 are not as certain and range from 11 5 to 13 6 ma 0 8 ma a shorter age range of 12 2 13 6 ma for this sequence is supported by its assignment to the d stauracanthus silicoflagellate subzone sedimentation rates were as high as 40 m per million years during deposition of the kirkwood formation suggesting possible tectonic influences on depositional history the timing of lower to middle miocene sequence boundaries from the new jersey coastal plain compares well with other indicators of sea level change including oxygen isotopes miller and others 1991b the global sea level record of haq and others 1987 and the offshore new jersey sequence boundaries of greenlee and others 1992 thus both tectonic and eustatic changes influenced miocene depositional history of the new jersey coastal plain

propagation directions of ocean surface waves inside tropical cyclones abstractsurface wave propagation inside tropical cyclones tcs is complicated and multiple wave systems are frequently observed the directional wave spectra acquired by hurricane hunters are analyzed to quantify its azimuthal and radial variations referenced to the hurricane heading the dominate feature in the front half of the tc coverage area is single wave systems propagating toward left and left front multiple wave systems are generally observed in the back and right quarters outside the radius of maximum wind rmw the directional differences and locations of occurrences of multisystem spectra are gaussian distributed the directional differences of the secondary and tertiary wave systems from the primary system are centered around 60 70 the minor systems are more likely on the left hand side of the primary system than on the right hand side by a 3 to 1 ratio the most likely azimuthal location of multisystem spectra is about 210 counterclockwise from the heading in the right front quarter

a comparison between the generalized digital environmental model and levitus climatologies two ocean climatologies of temperature and salinity the generalized digital environmental model gdem and the climatological atlas of the world ocean are compared dynamic height fields are computed by season from each climatology for the north atlantic north pacific and indian oceans and are compared on a 1 latitude longitude grid large scale oceanographic features are generally found to be similarly represented in both climatologies gdem appears to render better representations of seasonal variability and regions of high current shear such as the gulf stream because of a different smoothing method and a finer grid spacing maps of dynamic heights from both climatologies are presented and their similarities and differences are discussed the methodology for the construction of gdem is also described in detail

upper cretaceous sequences and sea level history new jersey coastal plain we developed a late cretaceous sea level estimate from upper cretaceous sequences at bass river and ancora new jersey odp ocean drilling program leg 174ax we dated 11 14 sequences by integrating sr isotope and biostratigraphy age resolution 0 5 m y and then estimated paleoenvironmental changes within the sequences from lithofacies and biofacies analyses sequences generally shallow up section from middle neritic to inner neritic paleodepths as shown by the transition from thin basal glauconite shelf sands transgressive systems tracts tst to medial prodelta silty clays highstand systems tracts hst and finally to upper delta front quartz sands hst sea level estimates obtained by backstripping accounting for paleodepth variations sediment loading compaction and basin subsidence indicate that large 25 m and rapid 1 m y sea level variations occurred during the late cretaceous greenhouse world the fact that the timing of upper cretaceous sequence boundaries in new jersey is similar to the sea level lowering records of exxon production research company epr northwest european sections and russian platform outcrops points to a global cause because backstripping seismicity seismic stratigraphic data and sediment distribution patterns all indicate minimal tectonic effects on the new jersey coastal plain we interpret that we have isolated a eustatic signature the only known mechanism that can explain such global changes glacio eustasy is consistent with foraminiferal 18 o data either continental ice sheets paced sea level changes during the late cretaceous or our understanding of causal mechanisms for global sea level change is fundamentally flawed comparison of our eustatic history with published ice sheet models and milankovitch predictions suggests that small 5 10 10 6 km 3 ephemeral and areally restricted antarctic ice sheets paced the late cretaceous global sea level change new jersey and russian eustatic estimates are typically one half of the epr amplitudes though this difference varies through time yielding markedly different eustatic curves we conclude that new jersey provides the best available estimate for late cretaceous sea level variations

sea level sediments and the composition of seawater the composition of seawater changed significantly during the course of the phanerozoic in concert with long term changes in sea level which were largely the result of changes in the volume of mid ocean ridges these reflect changes in the rate of seafloor spreading and determine the rate of seawater cycling through mid ocean ridges spencer and hardie 1990 and hardie 1996 proposed that the changes in the cycling rate of seawater through mid ocean ridges have been responsible for the changes in the composition of seawater during the phanerozoic this explanation cannot account for the major changes in the composition of seawater during the cenozoic which was a time of nearly constant seafloor spreading rate however changes in the rate of deposition of shallow water carbonates and their penecontemporaneous dolomitization can explain the cenozoic changes in seawater composition this indicates that sedimentologic parameters have played a major role in the chemical evolution of seawater the more rapid cycling of seawater through mors during the mesozoic can explain semiquantitatively the fairly minor differences between the composition of seawater in the eocene and in the jurassic changes in the composition of seawater during the paleozoic were probably determined both by changes in the rate of dolomite and gypsum anhydrite deposition and by changes in the rate of seawater cycling through mid ocean ridges if the causes of these compositional changes are the same as those during the cenozoic and mesozoic then sedimentologic factors have been significantly more important than the rate of cycling of seawater through mors in shaping the chemical evolution of seawater during the phanerozoic

evaluation of surface wind fields for prediction of directional ocean wave spectra during hurricane sandy abstract hurricane sandy was the largest storm on historical record in the atlantic ocean basin with extensive coastal damage caused by large waves and high storm surge in this study three different spatially varying surface wind and atmospheric pressure fields that are used for forecasting or hindcasting hurricane waves on the continental shelf are investigated these wind fields include two 2d parametric wind models holland model h80 generalized asymmetric holland model gahm and a 3d atmospheric model with data assimilation weatherflow regional atmospheric modelling system wrams these wind fields are used to drive wave hindcasts using coupled delft3d swan hydrodynamic and ocean wave models on a regional grid and the bulk wave statistics and the directional wave spectra are compared to observations at offshore wave buoys to investigate the impact of differences between the complex wind fields on predictions of the sea surface evolution the spatial and temporal distribution of bulk wave parameters are different for each wind field the wrams wind field produces wave model predictions in the best agreement with significant wave height observations followed by the gahm and h80 wind fields with mean correlation coefficients of 0 91 0 82 and 0 75 respectively averaged over 9 sites the directional wave spectra for hurricane sandy was bi modal predominantly in the two left quadrants of the hurricane in agreement with buoy observations the results indicate that a regional atmospheric wind model that has the best description of the wind field is the most appropriate forcing for hindcasting hurricane waves when detailed observations are available however a parametric vortex model that incorporates wind at multiple isotachs results in very good agreement with wave observations when used in the wave model and is a useful too for forecasting hurricane sea surface conditions the results of this study are relevant for other tropical cyclones that undergo extratropical transition or are influenced by other atmospheric disturbances at mid latitudes resulting in storms with large spatial size and high asymmetry

driftwood dropstones in middle miocene climate optimum shallow marine strata calvert cliffs maryland coastal plain erratic pebbles no certain proxy for cold climate abstract sparse lithic erratics pebbles to cobbles sampled from three shallow marine strata deposited during the middle miocene climate optimum mmco ca 16 14 ma along the western atlantic margin exposed in the calvert cliffs maryland suggest transport and deposition not from ice but from the roots of trees uprooted during floods and carried out to sea evidence for driftwood transport includes carbonized wood in the same strata more than half the ca 225 erratics were quarried in the largely metamorphic piedmont province including a few from the port deposit gneiss still outcropping on the lower susquehanna river the lowest sampled bed parker creek bone bed is assigned to the ca 15 7 15 5 ma peak warmth of the mmco which we attribute in part to co2 from the coevally erupted grande ronde flood basalts grfb the peak effusiveness episode of the columbia river flood basalts crfb the three sampled beds predate the ca 13 9 ma antarctic cryosphere expansion which may be recorded in the calvert cliffs by a unique buried channel

hurricane directional wave spectrum spatial variation in the open ocean abstract the sea surface directional wave spectrum was measured for the first time in all quadrants of a hurricane s inner core over open water the nasa airborne scanning radar altimeter sra carried aboard one of the noaa wp 3d hurricane research aircraft at 1 5 km height acquired the open ocean data on 24 august 1998 when bonnie a large hurricane with 1 min sustained surface winds of nearly 50 m s 1 was about 400 km east of abaco island bahamas the noaa aircraft spent more than five hours within 180 km of the eye and made five eye penetrations grayscale coded images of hurricane bonnie wave topography include individual waves as high as 19 m peak to trough the dominant waves generally propagated at significant angles to the downwind direction at some positions three different wave fields of comparable energy crossed each other partitioning the sra directional wave spectra enabled determination of the characteristics of the various components of the hurricane wave field and mapping of their sp

tertiary oxygen isotope synthesis sea level history and continental margin erosion tertiary benthic and planktonic foraminiferal oxygen isotope records are correlated to a standard geomagnetic polarity time scale making use of improved chronostratigraphic control and additional oligocene isotope data synchronous changes in both benthic and planktonic 18o values which occurred in the oligocene to miocene 36 5 2 ma are interpreted in part to represent ice growth and decay the inferred ice growth events correlate with erosion on passive continental margins as interpreted from seismic and chronostratigraphic records this association is consistent with a link between oligocene to miocene erosional events and rapid 15 m m y glacioeustatic lowerings of about 50 m high benthic foraminiferal 18o values suggest the presence of continental ice sheets during much of the oligocene to recent 36 0 ma substantially ice free conditions probably existed throughout the paleocene and eocene 66 36 ma the mechanisms and rates of sea level change apparently were different between the early and late tertiary with glacioeustatic changes restricted to the past 36 m y pre oligocene erosion on passive continental margins was caused by eustatic lowerings resulting from global spreading rate changes we apply a model which suggests that large areas of the continental shelves were subaerially exposed during such tectonoeustatic lowstands stimulating slope failure and submarine erosion the different mechanisms and rates of eustatic change may have caused contrasting erosional patterns between the early and late tertiary on passive continental margins this speculation needs to be confirmed by examination of data from several passive margins

effects of the gulf stream on ocean waves in the present study a third generation numerical wave model is used to study effects of a straight gulf stream and a gulf stream ring on ocean waves in swell and storm conditions the model accounts for all relevant processes of propagation generation and dissipation of the waves including current effects without imposing a priori restraints on the spectral development of the waves the dominating mechanism affecting the waves appears to be current induced refraction even though the short crestedness of the incoming waves tends to mask its effects also in swell conditions depending on wind and wave conditions refraction may trap locally generated waves in the straight gulf stream or it may reflect wave energy back to the open ocean in the gulf stream ring refraction induces a considerable variation in significant wave height and short crestedness but it hardly affects the mean wave direction in storm conditions the processes of generation and dissipation are considerably enhanced in countercurrent situations and reduced following current situations

reconstruction of tertiary progradation and clinoform development on the new jersey passive margin by 2 d backstripping we have reconstructed the oligocene to middle miocene paleobathymetry and stratigraphy of the new jersey margin using a modified backstripping technique by analyzing the geometry of the margin through time we investigate its response to fluctuating sea level changing climate and variable sediment supply during the tertiary the reconstructions reveal a change in the margin morphology from a more steeply dipping 1 300 to 1 500 carbonate ramp in the eocene to a flatter shelf with a sharp shelf edge at present this was accomplished by an increase in the terrigenous sediment supply that filled available accommodation and caused progradation across the margin we link the increase in sediment flux with climatic cooling rather than tectonic processes the progradation is evidenced by a series of clinoforms whose formation was modulated by sea level and which extend over 100 km across the shelf the height and dip of the clinoforms increased as they extended onto the deeper parts of the earlier ramp the miocene clinoform rollovers at the new jersey margin had water depths of60 130 m and are interpreted as the edge of a new continental shelf built over the older ramp sea level fall was probably insufficient to drive the miocene shorelines past the shelf breaks thus measurements of sea level amplitude based upon coastal onlap over the clinoforms are not reliable 1999 elsevier science b v all rights reserved

wind wave misalignment effects on langmuir turbulence in tropical cyclone conditions abstractthis study utilizes a large eddy simulation les approach to systematically assess the directional variability of wave driven langmuir turbulence lt in the ocean surface boundary layer

a hydraulic box model study of the mediterranean response to postglacial sea level rise 1 this paper quantifies the role of changing sea level in affecting mediterranean stratification using a new model of the strait basin system which allows for explicit time dependence during the last deglaciation fairbank s meltwater peak 1b leads to rapidly rising global sea levels and a freshening of the oceans and hence increasing influx of ever freshening atlantic water into the mediterranean basin owing to long residence times the salinity of the deep and intermediate water reservoirs would have decreased more slowly so that the basin was more stably stratified for a period with possible implications for sapropel formation our model is used to estimate the size of this reservoir effect in comparison to the freshwater influx from the opening of the black sea at the bosphorus it is found that this mechanism affects the stratification to a similar degree as the black sea opening other climatic mechanisms have also affected the freshwater budget of the mediterranean at this time but their sizes are more difficult to quantify

the relationship between riverine u series disequilibria and erosion rates in a basaltic terrain u series isotopes have been measured in the dissolved phase suspended load and bedload of the main rivers draining basaltic catchments in iceland for the dissolved phase 234u 238u and 238u 230th range between 1 08 and 2 2 and 7 4 and 516 respectively for the suspended load and bedload 234u 238u and 238u 230th range from 0 97 to 1 09 and from 0 93 to 1 05 respectively chemical erosion rates calculated from dissolved major elements range between 13 and 333 t km 2 yr 1 physical erosion rates have also been estimated from existing data and range between 21 and 4864 t km2 yr with an average of 519 t km 2 yr 1 u series disequilibria indicate that weathering in iceland operates at close to steady state conditions a model of continuous weathering indicates a maximum weathering timescale of 10 kyr with an average rate of uranium release into water of 1 6 10 4 yr 1 which is significant when compared to granitic terrains located at similar latitudes and to tropical basaltic terrains all river waters display 234u 238u greater than secular equilibrium consistent with the effects of alpha recoil the same dissolved phase 234u 238u exhibit a negative trend with physical erosion rates explained by the dominant effect of close to congruent chemical weathering of hyaloclastites in the younger basaltic terrains therefore chemical erosion rate and mineral weathering susceptibility play a major role in determining 234u 238u disequilibria in basaltic river waters comparison of global data for river basins in which weathering was recently strongly limited indicates a negative correlation between silicate weathering rates estimated with major elements and the age of weathering estimated with u series disequilibria this strongly suggests a key role of time and soil thickness on the chemical erosion of silicates

miocene to pliocene development of surface and subsurface temperatures in the benguela current system 1 the initiation of the benguela upwelling has been dated to the late miocene but estimates of its sea surface temperature evolution are not available this study presents data from ocean drilling program odp site 1085 recovered from the southern cape basin samples of the middle miocene to pliocene were analyzed for alkenone based u37k sstuk and glycerol dialkyl glycerol tetraether gdgt based tex86 temptex water temperature proxies in concordance with global cooling during the miocene sstuk and temptex exhibit a decline of about 8 c and 16 c respectively the temperature trends suggest an inflow of cold antarctic waters triggered by antarctic ice sheet expansion and intensification of southern hemisphere southeasterly winds a temperature offset between both proxies developed with the onset of upwelling which can be explained by differences in habitat alkenone producing phytoplankton live in the euphotic zone and record sea surface temperatures while gdgt producing thaumarchaeota are displaced to colder subsurface waters in upwelling influenced areas and record subsurface water temperatures we suggest that variations in subsurface water temperatures were driven by advection of cold antarctic waters and thermocline adjustments that were due to changes in north atlantic deep water formation a decline in surface temperatures an increased offset between temperature proxies and an increase in primary productivity suggest the establishment of the benguela upwelling at 10 ma during the messinian salinity crisis between 7 and 5 ma surface and subsurface temperature estimates became similar likely because of a strong reduction in atlantic overturning circulation while high total organic carbon contents suggest a biogenic bloom in the pliocene the offset between the temperature estimates and the cooling trend was reestablished

nonbreaking wave induced mixing in upper ocean during tropical cyclones using coupled hurricane ocean wave modeling the effects of turbulence generated by nonbreaking waves have been investigated by testing and evaluating a new nonbreaking wave parameterization in a coupled hurricane ocean wave model the mpi version of the princeton ocean model pom with hurricane forcing is coupled with the wavewatch iii ww3 surface wave model hurricane ivan is chosen as the test case due to its extreme intensity and availability of field data during its passage the model results are validated against field observations of wave heights and sea surface temperatures ssts from the national data buoy centre ndbc during hurricane ivan and against limited in situ current and bottom temperature data a series of numerical experiments is set up to examine the influence of the nonbreaking wave parameterization on the mixing of upper ocean the sst response from the modeling experiments indicates that the nonbreaking wave induced mixing leads to significant cooling of the sst and deepening of the mixed layer it was found that the nondimensional constant b1 in the nonbreaking wave parameterization has different impacts on the weak and the strong sides of the storm track a constant value of b1 leads to improved predictions on the strong side of the storm while a steepness dependent b1 provides a better agreement with in situ observations on the weak side a separate simulation of the intense tropical cyclone olwyn in north west australia revealed the same trend for b1 on the strong side of the tropical cyclone

variations in shoreface progradation and ravinement along the texas coast gulf of mexico shoreface architecture evolution mid holocene to present and depths of transgressive ravinement were examined from sabine pass at the texas louisiana border to south padre island near the texas mexico border using 30 shoreface transects shoreface transects extend out to 16 m water depth each created from an echo sounding profile and on average seven sediment cores the shoreface is composed of three broad sedimentological facies the upper shoreface composed almost entirely of sand the proximal lower shoreface composed of sand with thickly to medium bedded 50 10 cm mud and the distal lower shoreface composed dominantly of mud with medium to thinly bedded 20 3 cm sand shoreface architecture and evolution is extremely variable along the texas coast shoreface gradients increase from 2 25 m km 1 in east texas to 3 50 m km 1 in south texas shoreface sands coarsen towards south texas east and south texas shoreface deposits are thin and retrograding whereas central texas shoreface deposits are thicker and prograding central texas is characterized by stacked shoreface successions whereas in east texas lower shoreface sands are preserved only in offshore banks preservation of shoreface deposits is low in south texas although eustatic fluctuations and accommodation space have a strong impact on overall mid holocene to present shoreface evolution and preservation potential along strike variations in sediment supply and wave energy are the main factors controlling shoreface architecture the transgressive ravinement surface varies from 6 to 15 m along the texas coast

effect of cenozoic ice sheet fluctuations in antarctica on the stratigraphic signature of the neogene stratigraphic successions from the gulf of mexico offshore alabama northeast java indonesia ross sea antarctica and several other continental margins have been examined all are characterized by very similar neogene stratal geometries in seismic profiles and well log cross sections from these areas a large mid oligocene i e latest early oligocene earliest late oligocene basinward shift in coastal onlap is followed by a major early miocene transgression and aggradation which is in turn followed by early middle miocene transgressions and late middle and late miocene progradational episodes the succession culminates in plio pleistocene high frequency progradations and transgressions the interregional character of the neogene stratal signature and its similarity to the stratal geometry found in seismic data from the ross sea continental shelf antarctica suggest that the neogene stratal signature is a manifestation of glacioeustatic fluctuations a review of the literature and an analysis of recently acquired and published data indicate that the first major ice sheet grounding event in the ross sea occurred during middle to late oligoce time the ross sea is the repository for ice flowing from a major portion of the continental interior thus the glacial record of the ross sea should serve as a gage of ice volume changes on the continent that were large enough to influence global eustasy the ice advance onto the ross sea continental shelf during middle to late oligocene time may have been the result of a decrease in the rate of shelf subsidence as rifting in the ross sea slowed or ceased advance of the ice sheet resulted in widespread erosion of the continental shelf and shelf overdeepening it is hypothesized that metastable marine based ice sheets have waxed and waned on the antarctic continental shelf since at least the oligocene and that the these waxing and waning events were responsible for the development of a global neogene stratigraphic signature

wave current interaction between hurricane matthew wave fields and the gulf stream abstracthurricanes interact with the gulf stream in the south atlantic bight sab through a wide variety of processes which are crucial to understand for prediction of open ocean and coastal haza

interaction of langmuir turbulence and inertial currents in the ocean surface boundary layer under tropical cyclones abstractbased on a large eddy simulation approach this study investigates the response of the ocean surface boundary layer osbl and langmuir turbulence lt to extreme wind and complex wave forc

seismic stratigraphic framework of the continental shelf offshore delmarva u s a implications for mid atlantic bight evolution since the pliocene abstract understanding how past coastal systems have evolved is critical to predicting future coastal change using over 12 000 trackline kilometers of recently collected co located multi channel boomer sparker and chirp seismic reflection profile data integrated with previously collected borehole and vibracore data we define the upper

sea state dependence of the wind stress over the ocean under hurricane winds 1 the impact of the surface wave field sea state on the wind stress over the ocean is investigated with fetch dependent seas under uniform wind and with complex seas under idealized tropical cyclone winds two different approaches are employed to calculate the wind stress and the mean wind profile the near peak frequency range of the surface wave field is simulated using the wavewatch iii model the high frequency part of the surface wave field is empirically determined using a range of different tail levels the results suggest that the drag coefficient magnitude is very sensitive to the spectral tail level but is not as sensitive to the drag coefficient calculation methods the drag coefficients at 40 m s vary from 1 10 3 to 4 10 3 depending on the saturation level the misalignment angle between the wind stress vector and the wind vector is sensitive to the stress calculation method used in particular if the cross wind swell is allowed to contribute to the wind stress it tends to increase the misalignment angle our results predict enhanced sea state dependence of the drag coefficient for a fast moving tropical cyclone than for a slow moving storm or for simple fetch dependent seas this may be attributed to swell that is significantly misaligned with local wind

hurricane directional wave spectrum spatial variation at landfall abstract the nasa scanning radar altimeter sra flew aboard one of the noaa wp 3d hurricane research aircraft to document the sea surface directional wave spectrum in the region between charleston south carolina and cape hatteras north carolina as hurricane bonnie was making landfall near wilmington north carolina on 26 august 1998 two days earlier the sra had documented the hurricane wave field spatial variation in open water when bonnie was 400 km east of abaco island bahamas bonnie was similar in size during the two flights the maximum wind speed was lower during the landfall flight 39 m s 1 than it had been during the first flight 46 m s 1 also bonnie was moving faster prior to landfall 9 5 m s 1 than when it was encountered in the open ocean 5 m s 1 the open ocean wave height spatial variation indicated that hurricane bonnie would have produced waves of 10 m height on the shore northeast of wilmington had it not been for the continental shelf the gradual shoaling distributed t

a record of appalachian denudation in postrift mesozoic and cenozoic sedimentary deposits of the u s middle atlantic continental margin abstract the complex interplay between source terrain uplift basin subsidence paleoclimatic shifts and sea level change left an extensive sedimentary record in the contiguous offshore basins of the u s middle atlantic margin salisbury embayment baltimore canyon trough and hatteras basin isopach maps of 23 postrift lower jurassic to quaternary a allostratigraphic units coupled with a revised stratigraphic framework reveal that tectonism by regulating sediment supply accumulation rate dominated the interplay of forcing mechanisms tectonic pulses are evidenced by abruptly accelerated sediment accumulation marked latitudinal shifts in the location of depocenters and regional changes in lithofacies relatively rapid tectonic subsidence during the early and middle jurassic history of the basins may have enhanced sediment accumulation rates beginning in the late jurassic however subsidence rates decreased significantly though occasional short pulses of subsidence may have effected relative sea level rises sea level change heavily influenced the distribution and redistribution of sediments one they reached the basins and paleoclimate regulated the relative abundance of carbonates and evaporites in the basins we conclude that source terrains of the central appalachian highlands were tectonically uplifted intensely weathered and rapidly eroded three times since the late triassic 1 early to middle jurassic aalenian to callovian 2 mid early cretaceous barremian and 3 late cenozoic middle miocene intervals of tectonic quiescence following these three tectonic pulses provided conditions suitable for the formation of regional erosion surfaces geomorphic features commonly reported to characterize the central appalachian highlands this series of three irregularly spaced tectonic quiescent cycles does not however match the traditional four cycle concept of post triassic appalachian peneplanation

mid miocene paleoproductivity in the atlantic ocean and implications for the global carbon cycle 1 a prominent middle miocene 17 5 13 5 ma carbon isotope excursion ubiquitously recorded in carbonate sediments has been attributed to enhanced marine productivity and sequestration of 13c depleted organic carbon in marine sediments or enhanced carbon burial in peat lignite deposits on land here we test the hypothesis that the marine 13c record reflects a change in productivity with proxy records from three atlantic ocean sites deep sea drilling program site 608 and ocean drilling program sites 925 and 1265 our multiproxy approach is based on benthic foraminiferal accumulation rates elemental ratios ba al and p al the 13c of bulk sedimentary organic matter and dissolution indices we compare these proxies to benthic foraminiferal 13c values measured on the same samples our results indicate that marine paleoproductivity in the atlantic ocean is not related to the benthic foraminiferal 13c excursion a numerical box model confirms that marine productivity cannot account for the 13c maximum the model shows that sequestration of 1 5 1018 mol c in the terrestrial realm over a period of 3 ma leads to a 0 9 13c increase in the deep ocean which is near the observed records therefore an increase in continental organic carbon sequestration is the most plausible way to enrich the ocean s carbon pool with 13c which is consistent with coeval lignite deposits worldwide the 13c values of bulk sedimentary organic matter parallel the 13c of dissolved inorganic carbon as reflected by benthic foraminiferal 13c values suggesting no significant change in atmospheric pco2 levels over the investigated period

cenozoic global sea level sequences and the new jersey transect results from coastal plain and continental slope drilling the new jersey sea level transect was designed to evaluate the relationships among global sea level eustatic change unconformity bounded sequences and variations in subsidence sediment supply and climate on a passive continental margin by sampling and dating cenozoic strata from coastal plain and continental slope locations we show that sequence boundaries correlate within 0 5 myr regionally onshore offshore and interregionally new jersey alabama bahamas implicating a global cause sequence boundaries correlate with 18o increases for at least the past 42 myr consistent with an ice volume glacioeustatic control although a causal relationship is not required because of uncertainties in ages and correlations evidence for a causal connection is provided by preliminary miocene data from slope site 904 that directly link 18o increases with sequence boundaries we conclude that variation in the size of ice sheets has been a primary control on the formation of sequence boundaries since 42 ma we speculate that prior to this the growth and decay of small ice sheets caused small amplitude sea level changes 20 m in this supposedly ice free world because eocene sequence boundaries also appear to correlate with minor 18o increases subsidence estimates backstripping indicate amplitudes of short term million year scale lowerings that are consistent with estimates derived from 18o studies 25 50 m in the oligocene middle miocene and 10 20 m in the eocene and a long term lowering of 150 200 m over the past 65 myr consistent with estimates derived from volume changes on mid ocean ridges although our results are consistent with the general number and timing of paleocene to middle miocene sequences published by workers at exxon production research company our estimates of sea level amplitudes are substantially lower than theirs lithofacies patterns within sequences follow repetitive predictable patterns 1 coastal plain sequences consist of basal transgressive sands overlain by regressive highstand silts and quartz sands and 2 although slope lithofacies variations are subdued reworked sediments constitute lowstand deposits causing the strongest most extensive seismic reflections despite a primary eustatic control on sequence boundaries new jersey sequences were also influenced by changes in tectonics sediment supply and climate during the early to middle eocene low siliciclastic and high pelagic input associated with warm climates resulted in widespread carbonate deposition and thin sequences late middle eocene and earliest oligocene cooling events curtailed carbonate deposition in the coastal plain and slope respectively resulting in a switch to siliciclastic sedimentation in onshore areas oligocene sequences are thin owing to low siliciclastic and pelagic input and their distribution is patchy reflecting migration or progradation of depocenters in contrast miocene onshore sequences are thicker reflecting increased sediment supply and they are more complete downdip owing to simple tectonics we conclude that the new jersey margin provides a natural laboratory for unraveling complex interactions of eustasy tectonics changes in sediment supply and climate change

role of river suspended material in the global carbon cycle the reaction of ca derived from silicate weathering with co2 in the world s oceans to form carbonate minerals is a critical step in long term climate moderation ca is delivered to the oceans primarily via rivers where it is transported either as dissolved species or within suspended material the relative importance for climate moderation of riverine dissolved ca vs suspended ca transport stems from the total ca flux and its climate dependence data in the literature suggest that within uncertainty global riverine dissolved ca flux is equal to suspended material ca flux to determine how these fluxes depend on temperature and rainfall a 40 yr field study was performed on 4 catchments

surface wave field under binary typhoons sarika and haima 2016 in south china sea abstract the effects of the binary typhoon on the surface wave field in the south china sea scs were investigated using the third generation wave model wavewatch ww the surface wave field during the binary typhoons sarika and haima 2016 was reproduced with blended winds and two nested domains and the simulation results obtained are in good agreement with the satellite altimeter data to investigate different wave characteristics under binary and individual typhoons a numerical experiment was designed with the multi annual mean winds replacing one cyclone of the blended binary typhoons and its results were compared with the simulation results of realistic binary typhoons the comparison suggests that the surface waves induced by the binary typhoon not only have higher intensity but also exhibit more complex behaviors binary typhoons cause an increase in the significant wave height hs inside the maximum wind radius of the latter typhoon haima factors affecting the enhanced hs on the surface wave field include typhoon intensity maximum wind radius and typhoon translation speeds the interactions between waves generated by haima and sarika enhance extreme waves by 4 5 the response of wave characteristics of sarika and haima to the monsoon winds is different for wave spectra bi modal features are widespread on the surface wave field between the interval of the two typhoons even if the separation distance between them is greater than 1700 km

postimpact deformation associated with the late eocene chesapeake bay impact structure in southeastern virginia upper cenozoic strata covering the chesapeake bay impact structure in southeastern virginia record intermittent differential movement around its buried rim miocene strata in a graben detected by seismic surveys on the york river exhibit variable thickness and are deformed above the crater rim fan like interformational and intraformational angular unconformities within pliocene pleistocene strata which strike parallel to the crater rim and dip 2 3 away from the crater center indicate that deformation and deposition were synchronous concentric large scale crossbedded bioclastic sand bodies of pliocene age within 20 km of the buried crater rim formed on offshore shoals presumably as subsiding listric slump blocks rotated near the crater rim

effect of surface waves on air sea momentum exchange part i effect of mature and growing seas the effect of surface waves on air sea momentum exchange over mature and growing seas is investigated by combining ocean wave models and a wave boundary layer model the combined model estimates the wind stress by explicitly calculating the wave induced stress in the frequency range near the spectral peak the noaa ncep surface wave model wavewatch iii is used to estimate the spectra while the spectra in the equilibrium range are determined by an analytical model this approach allows for the estimation of the drag coefficient and the equivalent surface roughness for any surface wave fields numerical experiments are performed for constant winds from 10 to 45 m s21 to investigate the effect of mature and growing seas on air sea momentum exchange for mature seas the charnock coefficient is estimated to be about 0 01 0 02 and the drag coefficient increases as wind speed increases both of which are within the range of previous observational data with growing seas results for winds less than 30 m s 21 show that the drag coefficient is larger for younger seas which is consistent with earlier studies for winds higher than 30 m s 21 however results show a different trend that is very young waves yield less drag this is because the wave induced stress due to very young waves makes a small contribution to the total wind stress in very high wind conditions

ocean surface wave spectra inside tropical cyclones abstractdirectional wave spectra acquired in hurricane reconnaissance missions are compared with wind wave spectral models the comparison result is quantified with two indices of model measurement spectral agreement in the main region of hurricane coverage the indices vary sinusoidally with the azimuth angle referenced to the hurricane heading while showing a weak dependence on the radial distance from the hurricane center the measured spectra agree well with three models evaluated in the back and right quarters and they are underdeveloped in the front and left quarters the local wind and wave directions also show a weak radial dependence and sinusoidal variation along the azimuth the wind and wave vectors are almost collinear in the back and right quarters they diverge azimuthally and become almost perpendicular in the left quarter the azimuthally cyclical correlation between the indices of spectral agreement and the wind wave directional difference is well described by the sinusoidal variations

onlap offlap and the origin of unconformity bounded depositional sequences christie blick n 1991 onlap ofttap and the origin of unconformity bounded depositional sequences mar geol 97 35 56 unconformity bounded depositional sequences represent the fundamental building blocks of sedimentary successions they are typically characterized by onlap at the base and by offlap at the top and they tend to be markedly asymmetrical with onlap accounting for a larger part of any cycle of sedimentation than offlap offlap cannot be attributed solely to erosional truncation but instead implies that sequence boundaries develop over a finite interval of time depositional sequences are commonly associated with a cyclic arrangement of facies but transgressive regressive cycles are out of phase with respect to sequence boundaries which in down dip locations are both overlain and underlain by progradational deposits and hence form during times of regression of the shoreline these observations are used to develop some ideas about the origin of unconformity bounded sequences with reference to the inter related roles of changes in depositional base level and sediment supply in particular it is shown than onlap and offlap are due to lateral migration of a line of critical bypassing defined so as to incorporate the effects of sediment loading and compaction as well as the rate of change of elevation with respect to sea level downward shifts in onlap may be achieved by either an increase in the rate of eustatic fall or a decrease in the rate of tectonic subsidence and it is premature to assume that eustatic and tectonic controls on sea level may be distinguished solely on the basis of the frequency of depositional cyclicity small shifts in the position of onlap can also be produced by changes in sediment supply and more attention needs to be paid to the influence of sediment supply in the development of minor boundaries unconformities related to eustatic fluctuations are thought to correspond approximately to times of relatively rapid sea level fall inflection points but questions remain about the existence of possible leads and lags of up to cycle and hence about the degree to which sequence boundaries of eustatic origin may vary in age both within a given basin and from one basin to another

enhanced dissolution of basaltic glass in brackish waters impact on biogeochemical cycles in order to better constrain the geochemical budget of si in the ocean and potentially other elements released by the dissolution of silicates the alteration of riverine particulate material in estuaries and seawater needs to be estimated for this a series of alteration experiments of basaltic glass were performed at various degrees of salinity from 0 to 3 5 g l 1 in far from equilibrium conditions the solution used is a filtered natural seawater standard from the atlantic ocean the forward dissolution rates increase from 2 1 10 7 molsim 2s 1 s 0 gl 1 to 7 7 10 7 molsim 2s 1 s 3 5 gl 1 at 90 c and were extrapolated at 16 c from 2 9 10 10 molsim 2s 1 at s 0 gl 1 to 1 1 10 9 molsim 2s 1 at s 3 5 gl 1 this positive relationship between glass dissolution rate and salinity degree is consistent with published investigations concerning the role of specific cations and ligands present in seawater which can promote dissolution at the glass surface these results illustrate the potential of river basaltic glass particles to dissolve quickly in the water column after entering into the brackish waters of estuaries and before sinking on continental margins based on these dissolution rates and on assumptions on the particulate solid flux of fresh basaltic glass exported by rivers towards the ocean the corresponding flux of dissolved si is estimated to range between 2 and 8 1012 molsiyr 1 this is of the same order of magnitude as the estimated river dissolved si flux which represents therefore a significant input of si into the ocean additionally if the glass dissolution process remains congruent during the residence time of suspended particles into the water column the k flux to the ocean could also be significantly affected

numerical simulations and observations of surface wave fields under an extreme tropical cyclone abstract the performance of the wave model wavewatch iii under a very strong category 5 tropical cyclone wind forcing is investigated with different drag coefficient parameterizations and ocean current inputs the model results are compared with field observations of the surface wave spectra from an airborne scanning radar altimeter national data buoy center ndbc time series and satellite altimeter measurements in hurricane ivan 2004 the results suggest that the model with the original drag coefficient parameterization tends to overestimate the significant wave height and the dominant wavelength and produces a wave spectrum with narrower directional spreading when an improved drag parameterization is introduced and the wave current interaction is included the model yields an improved forecast of significant wave height but underestimates the dominant wavelength when the hurricane moves over a preexisting mesoscale ocean feature such as the loop current in the gulf of mexico or a warm and co

timing and magnitude of miocene eustasy derived from the mixed siliciclastic carbonate stratigraphic record of the northeastern australian margin article eustasy is a key parameter to understand sedimentary sequences on continental margins and to reconstruct continental ice volume in the cenozoic but timing and magnitude of global sea level changes remain controversial especially for the miocene epoch we analyzed sediment cores recovered from the marion plateau offshore northeastern australia during ocean drilling program odp leg 194 to define the mechanisms and timing of sequence formation on mixed carbonate siliciclastic margins and to estimate the amplitude of miocene eustatic adjustments we identified sequence boundaries on seismic reflection lines significantly revised the existing biostratigraphic age models and investigated the sedimentary response to sea level changes across the marion plateau we subdivided the miocene sediments into three sequence sets comprising a set of prograding clinoforms a muddy prograding carbonate ramp evolving into an aggrading platform and a lowstand ramp evolving into a backstepping ramp we recognized eight individual sequences dated at 18 0 ma 17 2 ma 16 5 ma 15 4 ma 14 7 ma 13 9 ma 13 0 ma and 11 9 ma we demonstrate that sequences on the marion plateau are controlled by glacio eustasy since sequence boundaries are marked by increases in 18 o deep sea miocene isotope events mi1b mbi 3 mi2 mi2a mi3a mi3 mi4 and mi5 respectively which reflects increased ice volume primarily on antarctica our backstripping estimates suggest that sea level fell by 26 28 m at 16 5 ma 26 29 m at 15 4 ma 29 38 m at 14 7 ma and 53 81 m at 13 9 ma combining backstripping with 18 o estimates yields sea level fall amplitudes of 27 1 m at 16 5 ma 27 1 m at 15 4 ma 33 3 m at 14 7 ma and 59 6 m at 13 9 ma we use a similar approach to estimate eustatic rises of 19 1 m between 16 5 and 15 4 ma 23 3 m between 15 4 and 14 7 ma and 33 3 m between 14 7 and 13 9 ma these estimates can be combined into a eustatic curve that suggests that sea level fell by 53 69 m between 16 5 and 13 9 ma this implies that at least 90 of the east antarctic icesheet was formed during the middle miocene the new independent amplitude estimates are crucial as the miocene is the geologic epoch for which the new jersey margin sea level record is poorly constrained

observations and modeling of typhoon waves in the south china sea abstractbuoy based observations of surface waves during three typhoons in the south china sea were used to obtain the wave characteristics with the local wind speeds kept below 35 m s 1 the surface waves over an area with a radius 5 times that of the area in which the maximum sustained wind was found were mainly dominated by wind wave components and the wave energy distribution was consistent with fetch limited waves swells dominated the surface waves at the front of and outside the central typhoon region next the dynamics of the typhoon waves were studied numerically using a state of the art third generation wave model wind forcing errors made a negligible contribution to the surface wave results obtained using hindcasting near realistic wind fields were constructed by correcting the idealized wind vortex using in situ observational data if the different sets of source terms were further considered for the forcing stage of the typhoon which was defined as the half inertial period before and aft

long term and short term global cenozoic sea level estimates backstripping analysis of three continuously cored well dated boreholes from the new jersey coastal plain ocean drilling program odp leg 150x indicates a long term 10 8 n10 7 yr eustatic fall of 100 m since 55 ma early eocene and suggests short term 0 5n3 m y eustatic falls of less than 70 m eustatic estimates are calculated from residuals between the decompacted unloaded and paleodepth corrected records and tectonic subsidence assuming a cooling lithospheric plate because the residuals are similar among the three sites we interpret them as an approximation of the eustatic signal

diagenesis and sr isotopic evolution of seawater using data from dsdp 590b and 575 new sr isotopic and concentration analyses of bulk carbonate and porewaters from a carbonate rich miocene section sampled at dsdp site 575 are reported and used along with our earlier data from a section of similar age at dsdp site 590b in a numerical model to determine for each site the rate of sr exchange during diagenesis and the degree to which this amount of exchange has shifted the87sr86sr of the bulk carbonate from the ratio each increment of sediment had when first deposited despite the fact that the two sites have very different water depth 4536 m at 575 vs 1299 m at 590b different sedimentation rate 10 m my at 575 vs 40 m my at 590b and significantly different porewater sr2 gradients we find that the rate of sr exchange as a function of sediment age is almost indistinguishable between the two sites the rate of sr exchange determined at the two sites is such that the resulting shift in bulk carbonate87sr86sr due to diagenesis is small compared to the total range of87sr86sr values measured but large compared to the analytical uncertainty of the individual isotopic ratio measurements by taking this shift into account we reconstruct the original87sr86sr of each increment of carbonate sampled which when plotted as a function of age becomes our best estimate of the sr isotopic evolution of seawater because sr is very well mixed in the ocean at any given time there is a single worldwide value of seawater87sr86sr therefore if we are quantitatively accounting for the effect sr exchange we should find the same seawater evolution curve regardless of what dsdp site is used when we compare the observed bulk carbonate87sr86sr vs age at the two sites they are seen to differ by amounts that are sometimes large compared to the analytical uncertainties of the measurements however when these data are corrected for the post depositional sr isotopic shifts predicted by our diagenetic model we find almost perfect agreement this agreement suggests that we have made a realistic determination of the rate of sr exchange and its consequences in terms of shifting the87sr86sr of the bulk carbonate and more importantly that sr isotopes can be used to correlate marine sediments with an accuracy comparable to the very small analytical uncertainties of modern isotopic measurements

correlating miocene sequences in onshore new jersey boreholes odp leg 150x with global δ18o and maryland outcrops recent onshore new jersey drilling ocean drilling program leg 150x provided excellent recovery of lower to middle miocene sequences that we dated with sr isotopic stratigraphy sequence boundaries correlate with deep sea 18 o increases inferred glacioeustatic lowerings indicating a primary control by global sea level change maryland miocene outcrops appear to correlate with new jersey sequences and the 18 o record although diagenesis and intense bioturbation limit sr isotopic age resolution in maryland the early miocene is not well represented in maryland due to regional tectonics in contrast early miocene accommodation in new jersey was provided by flexural effects due to sediment loading

oligocene miocene strontium isotopes stratigraphic revisions and correlations to an inferred glacioeustatic record this study tests and improves on previously published early and middle miocene 87sr 86sr marine correlations presents sr isotopic age correlations for this interval using the new timescale of cande and kent 1992 and evaluates sr isotopic changes against an inferred glacioeustatic proxy we generated a latest oligocene to early late miocene 87sr 86sr isotope record from ocean drilling program odp hole 747a this site provides an excellent magnetostratigraphic record during most of this interval for independent age estimates very good foraminiferal preservation and excellent core recovery comparisons of new 87sr 86sr data from hole 747a with previously published data from deep sea drilling project dsdp sites 608 miller et al 1991a and 588 hodell et al 1991 yield the following results 1 confirmation and refinement of the early miocene sr isotope changes 2 improved definition of the timing of the changes in slope of 87sr 86sr near 15 4 ma and 22 8 ma 3 improved sr isotopic age resolution for the middle miocene with resolution as good as 0 7 m y and 4 identification of an inflection in the sr isotope record at 28 0 ma based on the combined records from dsdp site 522 miller et al 1988 and odp hole 747a we have been unable to determine the cause of middle miocene offset between site 588 and hole 747a data although we believe it may be attributed to problems in the age assignments for hole 588a for the interval 14 11 ma and site 747 for the interval 11 8 ma because hole 747a results provide a better chronology than site 588 for most of the miocene and a better middle miocene sr isotope record than site 608 we propose that hole 747a serves as the best reference section for miocene 87sr 86sr variations from ca 23 to 11 ma using 87sr 86sr data from sites 522 608 and 747a we relate late eocene to early miocene inflections in the 87sr 86sr isotope record to oxygen isotope increases and decreases inferred to represent glacioeustatic events the decreases deglaciations observed in the 18o record apparently lead the 87sr 86sr inflections by 1 to 1 5 m y

unlocking the ice house oligocene miocene oxygen isotopes eustasy and margin erosion oxygen isotope records and glaciomarine sediments indicate at least an intermittent presence of large continental ice sheets on antarctica since the earliest oligocene circa 35 ma the growth and decay of ice sheets during the oligocene to modern ice house world caused glacioeustatic sea level changes the early eocene was an ice free greenhouse world but it is not clear if ice sheets existed during the middle to late eocene doubt house world benthic foraminiferal 18o records place limits on the history of glaciation suggesting the presence of ice sheets at least intermittently since the earliest oligocene the best indicator of ice growth is a coeval increase in global benthic and western equatorial planktonic 18o records although planktonic isotope records from the western equatorial regions are limited subtropical planktonic foraminifera may also record such ice volume changes it is difficult to apply these established principles to the cenozoic 18o record because of the lack of adequate data and problems in stratigraphic correlations that obscure isotope events we improved oligocene to miocene correlations of 18o records and erected eight oxygen isotope zones oi1 oi2 mi1 mi6 benthic foraminiferal 18o increases which are associated with the bases of zones oil circa 35 8 ma oi2 circa 32 5 ma and mil circa 23 5 ma can be linked with 18o increases in subtropical planktonic foraminifera and with intervals of glacial sedimentation on or near antarctica our new correlations of middle miocene benthic and western equatorial planktonic 18o records show remarkable agreement in timing and amplitude we interpret benthic planktonic covariance to reflect substantial ice volume increases near the bases of zones mi2 circa 16 1 ma mi3 circa 13 6 ma and possibly mi5 circa 11 3 ma possible glacioeustatic lowerings are associated with the 18o increases which culminated with the bases of zone mi4 circa 12 6 ma and mi6 circa 9 6 ma although low latitude planktonic 18o records are required to test this these inferred glacioeustatic lowerings can be linked to seismic and rock disconformities for example we link 12 oligocene early late miocene inferred glacioeustatic lowerings with 12 of the sequence boundaries inferred eustatic lowerings of haq et al 1987

filter or conveyor establishing relationships between clinoform rollover trajectory sedimentary process regime and grain character within intrashelf clinothems offshore new jersey u s a abstract clinoform geometries and trajectories are widely used to predict the spatial and temporal evolution of sand distribution but most analytical approaches underplay the significance of topset and shelf process regime in determining how and when sediment is conveyed downdip or stored on the continental shelf we present an integrated study of clinoform rollover trajectory and detailed grain character analysis to assess the role of topset process regime in determining sand distribution and sediment character across clinothems this study targets the topset foreset and bottomset deposits of four successive miocene intrashelf clinothem sequences which represent deposition under either river dominated or wave dominated conditions seismic reflection data was combined with core analysis and grain character data derived from 664 samples collected from three cored research boreholes in river dominated clinothems the transfer of coarse grained sediment occurs under both rising and flat to falling clinoform rollover trajectories suggesting that process regime is more important in determining sediment delivery than clinoform trajectory river dominated systems are effective conveyors of sediment into deeper water wave dominated clinothems deposited exclusively under rising clinoform rollover trajectories largely retain sand within topset and foreset deposits wave dominated systems are effective sediment filters notably deposition under either river or wave dominated topset process regimes results in quantifiable differences in grain character attributes along clinoform profiles sediments in river dominated systems are coarser less well rounded and more poorly sorted and show greater intersequence and intrasequence variability than those in wave dominated systems prediction of sediment character is more challenging in river dominated systems this study highlights the need for caution when attempting to predict downdip sand distribution from clinoform trajectory alone and provides a novel perspective into downdip grain character profiles under end member topset process regime conditions the results of this study can be used to better constrain sediment grain size and grain shape distributions in process based forward models and have widespread applications in prediction of reservoir quality in both frontier and mature hydrocarbon basins

numerical simulation of sea surface directional wave spectra under hurricane wind forcing numerical simulation of sea surface directional wave spectra under hurricane wind forcing was carried out using a high resolution wave model the simulation was run for four days as hurricane bonnie 1998 approached the u s east coast the results are compared with buoy observations and nasa scanning radar altimeter sra data which were obtained on 24 august 1998 in the open ocean and on 26 august when the storm was approaching the shore the simulated significant wave height in the open ocean reached 14 m agreeing well with the sra and buoy observations it gradually decreased as the hurricane approached the shore in the open ocean the dominant wavelength and wave direction in all four quadrants relative to the storm center were simulated very accurately for the landfall case however the simulated dominant wavelength displays noticeable overestimation because the wave model cannot properly simulate shoaling processes direct comparison of the model and sra directional spectra in all four quadrants of the hurricane shows excellent agreement in general in some cases the model produces smoother spectra with narrower directional spreading than do the observations the spatial characteristics of the spectra depend on the relative position from the hurricane center the hurricane translation speed and bathymetry attempts are made to provide simple explanations for the misalignment between local wind and wave directions and for the effect of hurricane translation speed on wave spectra

extricating dynamic topography from subsidence patterns examples from eastern north america s passive margin abstract global sea level eustatic histories generated by backstripping stratigraphy are predicated upon the lithosphere having a well understood tectonic history however sub plate processes play a role in governing lithospheric vertical motions with timescales and amplitudes akin to eustasy which are difficult to predict we examine how stratigraphic and geophysical observations combined with simple isostatic models can be used to disentangle histories of sub plate support and eustasy we focus on the passive margin of eastern north america where a generally accepted history of eustasy has been estimated negative long wavelength free air gravity anomalies residual ocean age depth estimates fast upper mantle shear wave velocities and geodynamic models suggest that cenozoic evolution of this passive margin has been influenced by upper mantle drawdown we build on existing analyses to backstrip sixteen wells which combined with seismic data constrain timing and extent of cenozoic subsidence results indicate up to 1000 m of water loaded subsidence between 20 0 ma centered on the baltimore canyon trough seismic data from the trough shows neogene aggrading clinoforms there is little evidence for faulting or stratigraphic growth which indicates that neogene lithospheric strain rates were low amplitude and spatial extent of neogene subsidence are difficult to explain by glacio eustasy or glacio isostatic adjustment instead sub plate support calculated from conversion of shear wave velocities to temperature and isostatic calculations indicate that upper mantle drawdown was responsible for subsidence of the margin because mantle convection is vigorous such observations are expected throughout the stratigraphic archive

extreme waves under hurricane ivan hurricane ivan a category 4 storm passed directly over six wave tide gauges deployed by the naval research laboratory on the outer continental shelf in the northeastern gulf of mexico waves were observed with significant wave heights reaching 17 9 meters and maximum crest to trough individual wave heights of 27 7 meters 91 feet analysis suggests that significant wave heights likely surpassed 21 meters 69 feet and that maximum crest to trough individual wave heights exceeded 40 meters 132 feet near the eyewall

sequence stratigraphy and marine to nonmarine facies architecture of foreland basin strata book cliffs utah u s a the desert member of the blackhawk formation and the castlegate sandstone in the book cliffs of utah and colorado were analyzed to develop a model of sequence stratigraphy and facies architecture in foreland basins stratal architecture of these rocks is controlled by two regionally extensive surfaces of incision and subaerial exposure interpreted as major sequence boundaries and at least six surfaces of incision and subaerial exposure with more limited lateral extent interpreted as minor sequence boundaries each sequence boundary is a regionally correlatable single surface major sequence boundaries can be traced from marine into proximal alluvial plain environments sequence boundaries have different physical expressions depending upon where in the basin they are observed strata beneath sequence boundaries are unrelated to strata above and time lines cannot be carried across these boundaries flooding surfaces called parasequence or parasequence set boundaries also exert an important control on facies architecture based on parasequence stacking patterns position of sequence boundaries and facies associations the desert member and castlegate sandstone have been divided into sequences with durations of 200 000 to 300 000 yr there are an order of magnitude more sequences in this interval than are predicted by the global sea level chart of haq et al 1988 the major sequences have been divided into the following systems tracts or sequence sets 1 grassy highstand sequence set below the desert sequence boundary named for the grassy member of the blackhawk formation 2 desert lowstand transgressive and highstand systems tracts between the desert and castlegate sequence boundaries 3 castlegate lowstand sequence set resting on the castlegate sequence boundary and 4 castlegate transgressive systems tract parasequence stacking patterns suggest that the grassy highstand sequence set and the desert highstand systems tract were deposited during a relative rise in baselevel the grassy highstand sequence set is punctuated by minor relative falls in baselevel both of these stratal units contain thick

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

observation based source terms in the third generation wave model wavewatch iii updates and verification abstractthe observation based source terms available in the third generation wave model wavewatch iii i e the st6 package for parameterizations of wind input wave breaking and swell dissipatio

onshore offshore correlations of cretaceous fluvial deltaic sequences southern baltimore canyon trough we evaluate cretaceous depositional sequences on approximately 4400 km 2700 mi of newly released multichannel seismic profiles and five wells on the continental shelf in the southern baltimore canyon trough and tie the data to three wells drilled onshore in the maryland coastal plain seismic geometries coupled with facies and biostratigraphy from the wells are used to delineate mid cretaceous aptian turonian depositional sequences and paleogeography beneath these sequences 400 1000 m 1300 3300 ft of lower cretaceous sedimentary rocks underlie the modern shelf they thicken along strike to the southwest implying a southern sediment source aptian to cenomanian sediments were deposited in shelf to nearshore settings a landward movement of the depocenter and a shift toward facies indicative of deeper paleodepths marks a 107 yr mid cretaceous transgression within which we identify five sequences a composite maximum flooding surface mfs within the uppermost of these retrogradational units is associated with the cenomanian turonian boundary and ocean anoxic event 2 shingled lower turonian seismic reflections prograde across the outer shelf downlapping onto the composite mfs and are truncated by a mid turonian sequence boundary the upper cretaceous section thickens seaward and along strike to the northeast implying a northern source and little late cretaceous accommodation beneath the modern shelf mid cretaceous strata offshore maryland are likely sand prone considering their proximity to the correlative fluvial facies of the onshore potomac group these potential reservoir sands are capped by regional confining units generated by 107 yr global mean sea level flooding events and are excellent targets for supercritical carbon storage

shelf margin architecture variability and its role in sediment budget partitioning into deep water areas abstract a review of 127 shelf margin accretion segments from 24 margins worldwide suggests that sediment flux can be low or high that shelf accommodation can be low medium or high and that climatic conditions can be icehouse or greenhouse the interplay of these three variables yields four main greenhouse margins and six main icehouse margins and thus has a fundamental control on shelf margin architectural styles providing new tools for predicting internal architecture of deep water systems in greenhouse settings there is commonly a strong supply drive because of higher temperatures more variable precipitation and higher sediment discharge but only modest shelf accommodation because of low frequency and low amplitude eustatic sea level changes low shelf accommodation is able to deliver significant volumes of sand sourced from either low or high sediment supply areas to deep water environments and residence time for deltas at greenhouse margins is likely to be relatively long because of the low amplitude of greenhouse sea level changes medium accommodation in contrast may overwhelm any low sediment supply but could be partly overwhelmed by high sediment supply which in turn can inhibit fans or encourage highstand fans in icehouse settings there is a strong cross shelf accommodation drive created by high frequency and high amplitude eustatic sea level changes thus causing significant and frequently repeated transits of river mouths and deltas across the shelf sandy basin floor fans created by low accommodation are predicted with either high or low sediment flux both medium and high accommodation can be volumetrically overwhelmed by high sediment supply which in turn cause greater volumes of sediment storage on the shelf resulting in volumetrically less significant highstand or transgressive submarine fans however a low supply may barely allow deltas to reach the shelf edge causing the deep water areas to be dominantly muddy

the role of the sediment load in sequence stratigraphy the influence of flexural isostasy and compaction simplified physically based models are utilized in order to examine the effects of sea level sedimentation tectonic subsidence isostatic compensation and compaction on development of unconformities unconformities divide volumes of relatively conformable sediments defining the time and spatial extent of sedimentary sequences the model parameters are varied both individually and in concert in order to isolate their contributions to sequence architecture these models reveal the importance of sedimentation and subsidence rates as well as sea level amplitude and rate in determining the type and extent of sequence boundary formed sedimentation and subsidence rate can vary significantly within and between margins producing different sequence boundaries given an identical eustatic sea level fall it is shown that sea level amplitude plays an important role in determining which systems tracts are present and sequence boundary timing for type 1 sequences and that sea level rate controls the same attributes in type 2 sequences isostatic compensation and compaction which have been described as secondary effects are shown to have considerable influence on sequence architecture these two processes due to isostatic response to sediment loading and sediment self loading initiate feedback by enhancing and partitioning accommodation space these additional effects invalidate application of the equilibrium point as a guide to where and how all accommodation space is created the manner in which flexure distributes accommodation space is a function of lithospheric rigidities higher rigidities partition space laterally producing wide shelves which favor type 1 sequence boundaries whereas lower rigidities partition space vertically forming narrow shelves which favor type 2 sequence boundaries compaction generates a net landward shift of the shelf edge and favors type 2 sequence development both isostatic compensation and compaction introduce time delays in sequence development one consequence of compaction is to rotate sedimentary packages generating growth and leakage of anticlinal structures as fluids are driven from the underlying section this process has important implications for hydrocarbon migration in compaction dominated systems such as the gulf of mexico margin

structural and tectonic setting of the charleston south carolina region evidence from the tertiary stratigraphic record eleven upper eocene through pliocene stratigraphic units occur in the subsurface of the region surrounding charleston south carolina these units contain a wealth of information concerning the long term tectonic and structural setting of that area these stratigraphic units have a mosaic pattern of distribution rather than a simple layered pattern because deposition erosion and tectonic warping have interacted in a complex manner through time by generating separate structure contour maps for the base of each stratigraphic unit an estimate of the original basal surface of each unit can be reconstructed over wide areas changes in sea level over geologic time generate patterns of deposition and erosion that are geographically unique for the time of each transgression such patterns fail to persist when compared sequentially over time in some areas however there has been persistent repetitive net downward or upward movement over the past 34 m y these repetitive patterns of persistent motion are most readily attributable to tectonism the spatial pattern of these high and low areas is complex but it appears to correlate well with known tectonic features of the region this correlation suggests that the tectonic setting of the charleston region is controlled by scissors like compression on a crustal block located between the north trending adams run fault and the northwest trending charleston fault tectonism is localized in the charleston region because it lies within a discrete hinge zone that accommodates structural movement between the cape fear arch and the southeast georgia embayment

impact effects and regional tectonic insights backstripping the chesapeake bay impact structure the chesapeake bay impact structure is a ca 35 4 ma crater located on the eastern sea board of north america deposition returned to normal shortly after impact resulting in a unique record of both impact related and subsequent passive margin sedimentation we use backstripping to show that the impact strongly affected sedimentation for 7 m y through impact derived crustal scale tectonics dominated by the effects of sediment compaction and the introduction and subsequent removal of a negative thermal anomaly instead of the expected positive thermal anomaly after this the area was dominated by passive margin thermal sub sidence overprinted by periods of regional scale vertical tectonic events on the order of tens of meters loading due to prograding sediment bodies may have generated these events