secondary circulation in a region of flow curvature relationship with tidal forcing and river discharge 1 on the basis of a 301 day acoustic doppler current profiler mooring in an estuarine tidal strait the strength and structure of secondary circulation in a region of flow curvature is related to variations in tidal forcing and river discharge during low flow conditions the structure of secondary flow is consistent with a centrifugally forced helical flow with bottom flow toward the inside of the bend and surface flow toward the outside of the bend the strength of secondary flow increases linearly with tidal range and is consistent with a vertical eddy viscosity that is linearly dependent on tidal current speed during times of high river discharge the strength of secondary flow is significantly reduced and its vertical structure undergoes a fundamental change over the spring neap cycle during spring tides the classic helical flow pattern is evident albeit weaker than during low flow conditions however during neap tides a more complex two cell structure is evident the change between these two states occurs with a spring neap transition in the subtidal flow indicating that it is also accompanied by changing stratification simple scaling analysis suggests that during weakly stratified conditions secondary circulation will influence stream wise dynamics and dispersion for channels with widths on order or less than 0 1 h cd where h is the water column depth and cd is a quadratic bottom drag coefficient in contrast during highly stratified conditions lateral excursions due to secondary flows are limited to approximately one tenth of the channel s width and are an ineffective lateral mixing agent

the formation of turbidity maximum zones by minor axis tidal straining in regions of freshwater influence abstractthis study investigates the influence of tidal straining in the generation of turbidity maximum zones tmz which are observed to extend for tens of kilometers along some shallow open coa

propagating rifts and continental breakup a simple quantitative model is proposed whereby continental breakup starts with a phase of continental rifting and continues with the propagation of rifts toward locked zones these zones are deformed in the rifting process while oceanic crust is generated in the wake of the rift tip the deformed zones will cause overlaps when a continental reassembly is attempted the model accounts for the shape and distribution of magnetic quiet zones at ocean continent boundaries and for the detailed geometry of some v shaped zones of oceanic magnetic anomalies the former provide an estimate of the scale at which the hypothesis of rigid plates fails and the latter are used to measure the velocity of rift propagation illustrations are provided for present rifting in the red sea and gulf of aden and for early rifting of the south atlantic and breakup of pangea

throughgoing crustal faults along the northern margin of the south china sea and their role in crustal extension a study of the rifled northern margin of the south china sea based on new single ship and two ship multichannel seismic data has revealed the presence of highly reflective steeply dipping normal faults which cut through the entire crust these faults with dips of 25 40 are associated with localized crustal thinning of 5 15 km and represent horizontal extension of the order of tens of kilometers a range of 5 20 km of horizontal extension has been measured along individual faults although the relative amount of horizontal extension taken up by these faults is modest compared to the total extension across the margin only about 15 or less the amount of localized crustal thinning which takes place along these fault surfaces is quite significant at one fault location the crustal thickness is reduced by 40 although the faults described have been recognized at three separate locations along the margin their trends appear to differ at each in two examples the faults are oblique to the inferred general north south extension direction of the margin this characteristic taken with the fact that some of the crustal faults also appear to serve as abrupt boundaries between broad regions of differing crustal thickness and reflectivity of the lower crust suggests that at least some of these faults were present prior to rifting such faults are postulated to have been former thrust faults perhaps associated with a triassic suture zone and or cretaceous subduction margin which have been reactivated as normal faults during subsequent rifting alternatively some of the throughgoing faults may represent crustal detachment surfaces that first formed as the result of a simple shear response to crustal extension

tides in a system of connected estuaries abstractthe spatial structure of tidal amplitude and phase in a simplified system of connected estuaries an idealized version of florida s intracoastal waterway is analyzed with a linear analytical model this model includes friction the earth s rotation and variable bathymetry it is driven at the connection with the ocean by a co oscillating tide model results compare well with observations of pressure and currents in a section of the intracoastal waterway on the east coast of florida the comparison suggests that the waterway is highly frictional causing the amplitude of the water elevation and tidal velocity to decrease away from the inlets to a minimum in the middle of the waterway the local phase relationship between velocity and water elevation changed nonlinearly from 90 with no friction to 45 with maximum friction in moderately to highly frictional basins the phase lag was consistently less than 45

baroclinic effects on wind driven lateral circulation in chesapeake bay abstractthe 2 month long mooring data were collected in a straight midsection of chesapeake bay to document the lateral circulation driven by along channel winds under upestuary winds the lateral circulation featured a clockwise looking into estuary circulation in the surface layer with lateral ekman forcing as the dominant generation mechanism under downestuary winds however the lateral circulation displayed a structure dependent on the wedderburn number w a counterclockwise circulation at small w and two counterrotating vortices at large w the surface lateral velocity was phase locked to the along channel wind speed analysis of the streamwise vorticity equation showed that the strength and structure of the lateral circulation in this stratified estuary were largely determined by the competition between the tilting of planetary vorticity by along channel currents and lateral baroclinic forcing due to sloping isopycnals under strong downestuary winds the lateral baroclinic forcing offset or

subtidal variability in water levels inside a subtropical estuary year long time series of water level are analyzed at five locations along the st johns river estuary florida to investigate propagation of subtidal pulses hilbert transformed empirical orthogonal functions heofs are obtained after a dominant seasonal signal is extracted from the data these functions provide information on spatial structure and propagation phase of subtidal water level pulses the first heof mode explains 96 of the subtidal variability and features an unusual spatial structure amplitude attenuation averaging 1 mm km to 55 km upstream slight amplification 0 16 mm km over the middle 70 km and attenuation 2 3 mm km over the final 18 km of the estuary the phase suggests a shift from progressive to quasi standing wave behavior at 55 km from the estuary mouth additionally local minima in the phase suggest two sources of subtidal forcing the coastal ocean and the upstream end an analytical model describing the evolution of long waves through a channel with frictional damping is fit to the amplitude of heof mode 1 solutions are obtained as a function of two parameters the nondimensional length of the basin and the nondimensional frictional depth values of between 0 55 and 0 67 and between 1 45 and 1 7 provide the best fit with the heof results 1 error or less these values indicate a highly frictional environment in which the average subtidal wavelength is 10 times the basin length subtidal pulses in this estuary therefore behave as damped waves that can be represented with idealized models

the origin and timing of multiphase cementation in carbonates impact of regional scale geodynamic events on the middle jurassic limestones diagenesis paris basin france the middle jurassic carbonates of the eastern part of the paris basin display surprisingly low values of porosity and permeability 15 and k 0 5 md the main objective of this study is to determine the causes and timing of the cementation that altered the petrophysical properties of these carbonates thereby destroying their potential as oil reservoirs a fate that did not befall their equivalents in deeper central parts of the paris basin using petrographic and geochemical analyses stable o and c isotopes sr isotopes major elements we identify six calcitic spar stages two dolomite stages and several episodes of fracturing and stylolitization ordered in paragenetic sequence cement quantification shows the predominance of two blocky calcite cement stages 75 of total cementation o and sr isotopes from these calcite cements suggest that the parent fluids resulted either from a mixing of trapped jurassic seawater and meteoric water or from buffered meteoric waters in the geological history of the paris basin major meteoric water inputs were possible during the early cretaceous when the middle jurassic carbonates cropped out at its northern and eastern borders lateral meteoric recharge may have occurred as a result of two separate uplift events late cimmerian unconformity and late aptian unconformity and the related exposures of carbonates to the north of the study area this palaeohydrological circulation brought about a significant reduction of porosity from 40 to 10 through calcite cement precipitation the early cretaceous events are of great importance in the diagenetic evolution of the sedimentary basins bordering the london brabant massif across all of northwestern europe a subsequent dolomite and calcite cementation stage accounts for about 5 of the total cement volumes this late cementation may have been caused by hydrothermal fluids ascending along permeable fractures during the late oligocene extension episode

geometry of propagating continental rifts reconstruction of past plate configurations through palinspastic restoration of continental margins1 4 requires a detailed knowledge of the geometries of horizontal continental extension extension is often restricted to discrete linear zones termed rifts5 6 and rift models that invoke propagating vertical dykes and cracks7 10 are useful for assessing the relative significance and timing of uplift subsidence and extension in the tectonic evolution of rift basins however many models do not adequately account for the observed asymmetry of rifts i describe here the general three dimensional character of young and aborted continental rifts which can be used to derive a structural model for the propagation of rifts in continental lithosphere the rifts become asymmetric as a consequence of the role played by low angle normal faults in the overall rift geometry

three dimensional tidal flow in an elongated rotating basin the three dimensional tidal circulation in an elongated basin of arbitrary depth is described with a linear constant density model on the f plane rotation fundamentally alters the lateral flow introducing a lateral recirculation comparable in magnitude to the axial flow as long as friction is not too large this circulation is due to the imbalance between the cross channel sea level gradient which is in near geostrophic balance with the coriolis acceleration associated with the vertically averaged axial flow and the coriolis acceleration associated with the vertically sheared axial flow during flood condition for example the lateral coriolis acceleration near the surface exceeds the pressure gradient tending to accelerate the lateral flow while the converse is true near the bottom as a result with rotation fluid parcels tend to corkscrew into and out of the basin in a tidal period the axial flow is only weakly modified by rotation when friction is small the axial velocity is uniform in each section except in a narrow bottom boundary layer where it decreases to zero the boundary layer thickness increases with friction so that with moderate or large friction axial velocities are sheared from bottom to surface when friction is large the local and coriolis accelerations are both small and the dynamics are governed by a balance between friction and the pressure gradient

continental rifting and the implications for plate tectonic reconstructions previous plate tectonic reconstructions have tried to recreate the pre rifting pangea configuration of the continents by matching contours or lineaments that are thought to represent the continental boundaries such reconstructions have the inherent assumptions that no extension occurs within the continent during rifting that the continental boundaries are isochrons and that the continents rift without distortion this paper proposes a model for continental breakup with distortion where ocean basins are formed by propagating rifts this model challenges the assumptions made by previous reconstructions and presents a new method for representing the prerift geometry of the continents as rifts propagate through a continent the region in front of the rift extends by continental faulting and crustal thinning while the region behind the rift expands by seafloor spreading the propagating rift model implies that large amounts of continental extension up to 150 km occur and that the continental boundaries are not isochrons this extension due to rifting results in apparent overlap when the continents are returned to their original configuration because of the gradational nature of this extension the best representation of the pre rift configuration is obtained by matching the initial rifting point and having overlap increase in the direction of rift propagation the overlap is equivalent to the amount of extension that has taken place on both continental edges reconstructions based on this model are presented for the gulf of california the gulf of aden the norwegian greenland sea and the south atlantic ocean they are able to resolve the discrepancies that occur when rigid plate tectonics are applied this model has implications that can be used to predict the age and structure of the continental shelves and the location and orientation of the oldest magnetic isochrons

secondary circulation in a highly stratified estuary observations from the hudson river estuary are presented to discuss the interaction between secondary flows and stratification in the vicinity of a headland during highly stratified conditions analysis of the cross stream momentum balance suggests that centrifugal accelerations are in near balance with the cross stream baroclincity results emphasize that the interaction between stratification and secondary flows can set up a cross stream internal seiche this results in a reduction and subsequent reversal of the secondary flows downstream of a headland simple scaling arguments suggest that the spin down time for tidally driven eddies is related to stratification

impact of stylolites on the mechanical strength of limestone abstract we performed a series of uniaxial compression tests on samples of microporous carbonates from the paris basin bure france sedimentary stylolites are pervasive in these formations we show that the porosity in the vicinity of the stylolites is always higher than that of the host rock as a result our new mechanical data reveal that samples with a stylolite are always measurably weaker with respect to the adjacent stylolite free material however when present the orientation of the stylolite with respect to the direction of loading does not result in any mechanical anisotropy numerical simulations using a 2d finite element code suggest that the weakening induced by the presence of a stylolite is mostly due to the higher porosity and the higher level of heterogeneity in and around the stylolite while the absence of mechanical anisotropy is due to the roughness of the stylolite while the presence of stylolites weakens carbonate rocks stylolites only act as planes of weakness when their thickness exceeds a certain threshold about 5 mm

a new stylolite classification scheme to estimate compaction and local permeability variations we modeled the geometrical roughening of bedding parallel mainly layer dominated stylolites in order to understand their structural evolution to present an advanced classification of stylolite shapes and to relate this classification to chemical compaction and permeability variations at stylolites stylolites are rough dissolution seams that develop in sedimentary basins during chemical compaction in the zechstein 2 carbonate units an important lean gas reservoir in the southern permian zechstein basin in germany stylolites influence local fluid flow mineral replacement reactions and hence the permeability of the reservoir our simulations demonstrate that layer dominated stylolites can grow in three distinct stages an initial slow nucleation phase a fast layer pinning phase and a final freezing phase if the layer is completely dissolved during growth dissolution of the pinning layer and thus destruction of the stylolite s compaction tracking capabilities is a function of the background noise in the rock and the dissolution rate of the layer itself low background noise needs a slower dissolving layer for pinning to be successful but produces flatter teeth than higher background noise we present an advanced classification based on our simulations and separate stylolites into four classes 1 rectangular layer type 2 seismogram pinning type 3 suture sharp peak type and 4 simple wave like type rectangular layer type stylolites are the most appropriate for chemical compaction estimates because they grow linearly and record most of the actual compaction up to 40 mm in the zechstein example seismogram pinning type stylolites also provide good tracking capabilities with the largest teeth tracking most of the compaction suture sharp peak type stylolites grow in a non linear fashion and thus do not record most of the actual compaction however when a non linear growth law is used the compaction estimates are similar to those making use of the rectangular layer type stylolites simple wave like stylolites are not useful for compaction estimates since their growth is highly non linear with a very low growth exponent in the case where sealing material is collected at the tooth during dissolution stylolites can act as barriers for local fluid flow as they intensify sealing capabilities of pinning layers however the development of teeth and spikes offsets and thus destroys continuous stylolite seams so that the permeability across the stylolite becomes very heterogeneous and they are no continuous barriers this behavior is best shown in rectangular layer and seismogram pinning type stylolites that develop efficient fluid barriers at teeth tips but destroy sealing capabilities of layers by offsetting them at the flank leading to a permeability anisotropy along 2 d stylolite planes suture sharp peak stylolites can create fluid barriers if they collect enough sealing material however if the collecting material does not seal or if spikes offset the sealing material the stylolite leaks we propose that our classification can be used to realistically estimate chemical compaction in reservoirs and gives an indication on how heterogeneous the permeability of stylolites can be

fingerprinting stress stylolite and calcite twinning paleopiezometry revealing the complexity of progressive stress patterns during folding the case of the monte nero anticline in the apennines italy in this study we show for the first time how quantitative stress estimates can be derived by combining calcite twinning and stylolite roughness stress fingerprinting techniques in a fold and thrust belt first we present a new method that gives access to stress inversion using tectonic stylolites without access to the stylolite surface and compare results with calcite twin inversion second we use our new approach to present a high resolution deformation and stress history that affected meso cenozoic limestone strata in the monte nero anticline during its late miocene pliocene growth in the umbria marche arcuate ridge northern apennines italy in this area an extensive stylolite joint vein network developed during layer parallel shortening lps as well as during and after folding stress fingerprinting illustrates how stress in the sedimentary strata did build up prior to folding during lps the stress regime oscillated between strike slip and compressional during lps before ultimately becoming strike slip again during late stage fold tightening our case study shows that high resolution stress fingerprinting is possible and that this novel method can be used to unravel temporal relationships that relate to local variations of regional orogenic stresses beyond regional implications this study validates our approach as a new powerful toolbox to high resolution stress fingerprinting in basins and orogens combining joint and vein analysis with sedimentary and tectonic stylolite and calcite twin inversion techniques

finite extension across the south vietnam basins from 3d gravimetric modelling relation to south china sea kinematics abstract we derive a crustal thickness map over the south vietnam basins from a 3d inversion of gravity data that takes into account the sedimentary infill and its density variation with depth this map is used to estimate the total amount of stretching across these basins that varies from 190 km to the east at 111 e to 30 km to the west at 107 e comparison with south china sea kinematics amount and timing of oceanic opening implies large decoupling with respect to the indochina block and supports the hypothesis of formation of the south china sea in upper oligocene to lower miocene by southward subduction of the proto south china sea

a two dimensional analytic tidal model for a narrow estuary of arbitrary lateral depth variation the intratidal motion an innovative method is introduced to solve a two dimensional depth averaged analytic model for narrow estuaries or tidal channels with arbitrary lateral depth variations the solution is valid if the lateral variation of the amplitude of tidal elevation a is small i e a a where a is the amplitude of the tidal elevation this assumption is supported by a 60 day observation of elevation in the james river estuary using pressure sensors at both sides of a cross section of the estuary the error introduced by the solution is of the order of a a which has a maximum of 5 in the james river estuary the propagation of the tidal wave elevation is therefore essentially one dimensional along the estuary regardless of the depth distribution whereas tidal velocity has a strong transverse shear and is three dimensional in general dozens of depth functions in six groups of various forms are used to calculate the solution the tidal velocity is highly correlated with the bathymetry the largest amplitude of the along channel velocity is in the deepest water the phase of the along channel velocity in the shallow water leads that in deep water causing a delay in time of flood or ebb in the deep water the transverse velocity is generally small in the middle of a channel but reaches its maximum over the edges of bottom slopes the depth function has a significant effect on the ellipticity and the sense of rotation of the tidal ellipses by fitting the observed phase of semidiurnal tide in the james river estuary to the phase of the momentum equation we have obtained optimal values of the drag coefficient 1 5 10 3 and 1 8 10 3 for the spring and neap tides respectively then we apply these values of the drag coefficient and the model to the james river estuary using the real bathymetry results show remarkable agreement between the observations and the model along the transects for both spring and neap tides the cross channel phase difference of the along channel velocity between the channel and the shoal is found to be 1 hour a value consistent with that from the model the model estimated lateral variation of elevation is 2 5 of the tidal amplitude which is slightly smaller than the observed value

the dynamics of a partially mixed estuary measurements of velocity density and pressure gradient in the lower hudson river estuary were used to quantify the dominant terms in the momentum equation and to characterize their variations at tidal and spring neap timescales the vertical momentum flux assumed to be due mainly to turbulent shear stress was estimated indirectly based on the residual from the acceleration and pressure gradient terms the indirect estimates of stress compared favorably to bottom stress estimates using a quadratic drag law supporting the hypothesis that the tidal momentum equation involves a local balance between tidal acceleration pressure gradient and stress divergence estimates of eddy viscosity indicated that there was significant tidal asymmetry with flood tide values exceeding ebb values by a factor of 2 as a consequence of the asymmetry the vertical structure of the tidally averaged stress bore no resemblance to the tidally averaged shear in spite of the asymmetry of vertical mixing the tidally averaged estuarine circulation was found to depend simply on the intensity of bottom turbulence which could be parameterized by a rayleigh drag formulation based on the tidal velocity magnitude and the tidally averaged near bottom flow this seemingly paradoxical result indicates that the estuarine circulation can be modeled without detailed knowledge of the effective eddy viscosity only requiring an estimate of the bottom drag coefficient the tidal forcing conditions and the baroclinic pressure gradient a notable characteristic of this solution is an inverse dependence of the estuarine circulation on the amplitude of the tides

tidal and subtidal hydrodynamics and energetics in a constricted estuary abstract the dynamics of coastal plain estuaries are mainly associated with variable tidal forcing and local winds in combination with bathymetric complexity and coastline irregularity specific features such as constricted areas can potentially affect and energize the hydrodynamics of these types of systems particularly tidal range and tidal currents can be significantly amplified where the incoming tidal wave becomes constricted in this work the impact of a narrow constriction on a mesotidal estuary was analysed at tidal and subtidal time scales tidal hydrodynamics energy fluxes and energy dissipation were determined for the entire cadiz bay southwestern spain using the delft3d numerical model field observations were used to analyse tidal propagation and energy dissipation along the bay constriction and to calibrate and test the numerical model the results indicate that the presence of the constriction transformed and distorted the tide and increased the tidal range and flow velocities along the channel with implications on energy dissipation the tidal currents were oriented along channel at the central part of the constriction although abrupt bathymetric changes at the channel inner boundary provoked a sudden rotation of the flow although the energy fluxes were higher for spring tides and were strongly influenced by winds the energy dissipation was controlled by bed shear stresses and vertical dispersion the significance of this energy dissipation was that it destabilized the water column which resulted in a weakly stratified system with implications on water quality at a subtidal scale the residual water volume exchange was the result of the combined effects of the neap spring tides wind and waves whereas tides were dominant at the tidal scale

circulation and haline structure of a microtidal bay in the sea of japan influenced by the winter monsoon and the tsushima warm current mooring and hydrographic surveys were conducted in tango bay a microtidal region of freshwater influence rofi in the sea of japan in order to clarify the circulation pattern in the bay and its driving forces monthly mean velocity records at four stations revealed an inflow and outflow at the eastern and northern openings of the bay respectively indicating an anticyclonic circulation across the bay mouth the circulation was significantly intensified in winter in accordance with the prevailing nw wind component of the winter monsoon the anticyclonic circulation at the bay mouth was connected to an estuarine circulation that was evident near the mouth of the yura river at the bay head surface salinity just offshore of the river mouth was closely related to the yura river discharge whereas in lower layers the offshore water had a stronger influence on salinity prior to a seasonal increase in the yura river discharge summer salinity decreased markedly through the water column in tango bay possibly reflecting intrusion of the changjiang diluted water transported by the tsushima warm current in contrast with the traditional assumption that estuarine circulation is controlled mainly by river discharge and tidal forcing the circulation in tango bay is strongly influenced by seasonal wind and the tsushima warm current the narrow shelf may be responsible for the strong influence of the tsushima warm current on circulation and water exchange processes in tango bay

the geometry of propagating rifts abstract the kinematics of two different processes are investigated both of which have been described as rift propagation courtillot uses this term to describe the change from distributed to localised extension which occurs during the early development of an ocean basin the term localisation is instead used here to describe this process to distinguish it from hey s type of propagation localisation generally leads to rotation of the direction of magnetisation to hey propagation means the extension of a rift into the undeformed plate beyond a transform fault detail surveys of the galapagos rift have shown that the propagating and failing rifts are not connected by a single transform fault but by a zone which is undergoing shear the principal deformation is simple shear and the kinematics of this deformation are investigated in some detail the strike of most of the lineations observed in the area can be produced by such deformation the mode of extension on the propagating rift appears to be localised for some periods but to be distributed for others neither simple kinematic arguments nor stretching of the lithosphere with conservation of crust can account for the observed variations in water depth

two layer tidal circulation in a frictional rotating basin the three dimensional tidal circulation in an elongated basin of arbitrary depth is described with a coupled barotropic and baroclinic two layer model on the f plane as long as friction is not dominant near standing waves are present on the interface as well as on the surface the surface pattern is principally determined by the product of the tidal barotropic wavenumber by the basin length the interface deformation is determined by a baroclinic equivalent usually a much larger number as a result the shape of the interface is characterized by horizontally smaller features than the surface if the product of the tidal baroclinic wavenumber by the basin width is greater than one both lateral and axial modes can be excited at the interface if these modes are near resonant large internal tides can be forced directly by the co oscillating surface tide at the basin entrance the amplitude and phase of the baroclinic component are sensitive functions of the density anomaly and the interface depth as a result the phase and amplitude of the interface vary by large amounts with comparatively small changes in those parameters the model behavior is qualitatively consistent with observations in fjords and straits

anisotropic scaling of tectonic stylolites a fossilized signature of the stress field 1 vertical stylolites are pressure solution features which are considered to be caused by horizontal tectonic loading with the largest principal compressive stress being sub parallel to the earth s surface in the present study we analyze the roughness of such tectonic stylolites from two tectonic settings in southern germany and northeastern spain aiming to investigate their scaling properties with respect to the stress during formation high resolution laser profilometry was carried out on opened stylolite surfaces of nine samples these data sets were then analyzed using one and two dimensional fourier power spectral approaches we found that tectonic stylolites show two self affine scaling regimes separated by a distinct crossover length l as known for bedding parallel stylolites in addition tectonic stylolites exhibit a clear in plane scaling anisotropy that modifies l since the largest and smallest crossover lengths are oriented with the sample vertical and horizontal directions i e 2 and 3 and l is a function of the stress field during formation as analytically predicted we conclude that the scaling anisotropy of tectonic stylolites is possibly a function of the stress field knowledge of this crossover length anisotropy would enable the reconstruction of the full three dimensional stress tensor if independent constraints of the depth of formation can be obtained

characterization of major discontinuities from borehole cores of the black consolidated marl formation of draix french alps a quantitative description of rock discontinuities present in subsurface cores that were drilled down to 20 m in the marls of the laval and moulin catchments near draix france is presented three kinds of discontinuities are studied those fully open those open but filled with clay rich material and those sealed with calcite with a laser profiler the topography of facing sides of typical discontinuities was measured with a normal resolution of 1 m the probability distribution of the elevation of each surface are obtained and shown to be normal possible self affine scaling invariance of the topography were explored the mineralogical content of an interface between the marl bulk and the embedded calcite vein is also investigated using x ray computed tomography implication of this study for water transport in such discontinuities is addressed in a companion paper in the same issue copyright 2011 john wiley sons ltd

periodic wind driven circulation in an elongated and rotating basin abstract an idealized model is developed for the three dimensional response of a coastal basin e g lagoon bay or estuary to time periodic wind stress this model handles basins that are deeper and or shallower than an ekman depth with wind forcing frequencies ranging from subinertial to superinertial here the model is used to describe how the response current and sea level of a basin deeper than one ekman depth depends on the wind forcing frequency at low subinertial frequencies the response is similar to the steady wind case and is hence called quasi steady there is a near surface ekman transport to the right of the wind balanced by a return flow at depth lateral bathymetric variations introduce an along basin circulation that decays with increasing frequency and sets the extent of the quasi steady response in the frequency domain at the inertial frequency the wind forces a damped resonant response with large vertical shear and weak depth integrated flow this result is potentially impor

chronology of fracture sealing under a meteoric fluid environment microtectonic and isotopic evidence of major cainozoic events in the eastern paris basin france abstract a detailed reappraisal of the sequence of tectonic stages that has affected the eastern part of the paris basin from the late jurassic to the end of cainozoic is presented in order to improve knowledge of the relationships between tectonics and fluid mass palaeo transfers in that basin this goal was performed in two steps i establishing a relative tectonic chronology on the basis of numerous observations and detailed analysis of geometrical relationships between striated planes vertical and bedding stylolites and tension gashes and ii discussing the geochemical signatures 18 o and 13 c of calcite from fracture infillings well positioned within the relative tectonic chronology the resulting tectonic sequence agrees with the main events described by previous papers but the present work details the pyrenean s l eocene oligocene and alpine miocene pliocene convergence stages and explains the mechanisms of the oligocene miocene transition between the two previous events the different tectonic stages are as follows i late jurassic to early cretaceous extension starting with a wnw ese direction but changing to e w ii the pyrenean convergence eocene changing from nne ssw to ne sw and finally ene wsw compression iii oligocene transition from pyrenean to alpine convergence marked by a drastic evolution of main stress which swaps from a horizontal position to a vertical one and radial extension marked by a strong reactivation of bedding stylolitisation iv the alpine convergence late miocene to present day changing from wnw ese to nnw sse direction of shortening 18 o and 13 c values of calcite from tension gashes associated to each tectonic stage spread from 18 to 27 smow and from 0 8 to 3 pdb respectively according to the maximum thermal history of this part of the basin t max 40 c or 60 c according to the available published estimates the calculated 18 o values of fluids 7 to 4 involved in mass transfer processes are interpreted as meteoric the lowest 18 o values 18 20 are located around the main regional faults and associated with 13 c values that are rather different from those of host rocks in contrast calcites from non faulted area present a higher 18 o 20 and 13 c values close to those of host rocks these data are explainable in terms of differences in the fluid rock ratios prevailing during carbonate redistribution the highest ratios being associated to discontinuities faults sometimes with hydraulic breccias that were active during the tertiary tectonic events outside the fault zones the isotopic compositions of calcite from tension gashes are similar at the regional scale to those of calcite from geodes or cements analysed in previous studies on localized areas as a result we emphasize the fact that a significant part of the carbonate redistribution in the middle to upper jurassic limestones from the eastern paris basin occurred during the tertiary s l enlightening the influence of distant orogenic systems extensive or compressive in the matter redistribution within sedimentary basins at variance of models inferring a porosity cementation predominantly during burial

rheological characterization of a sedimentary formation from a stress profile inversion summary detailed stress measurements have been carried out within a sedimentary sequence composed of a hard clay formation laying horizontally between two limestone units in the eastern paris basin france orientations of the minor and major horizontal principal stresses are found to be in good agreement with the direction of major shortening that prevailed during the last tectonic stage however their magnitudes exhibit an intriguing evolution with depth while the magnitude of the maximum horizontal stress slowly but regularly increases with depth the magnitude of the minimum horizontal one is larger in the hard clay formation than in the surrounding limestone units contrary to expectation from simple elastic considerations an analytical calculation demonstrates that the genesis of the current stress state may be reproduced by taking into account horizontal strains in two different directions and simulating erosion of part of the overburden with a viscoelastic model for the hard clay and an elastic behaviour for the limestone however the elastic constants that are derived for the limestone in order to fit the measured stress field correspond to a material that is more deformable and has a lower poisson s ratio than predicted by laboratory tests this discrepancy may be explained by a slow long term deformation process in the limestone possibly associated with pressure solution

tidal and subtidal exchange flows at an inlet of the wadden sea abstract observations of underway velocity profiles during complete spring and neap tidal cycles were used to determine whether the spatial structures of tidal and subtidal flows at a tidal inlet in a multiple inlet embayment are consistent with those observed at single inlet embayments measurements were obtained at the otzumer balje one of the multiple inlets among the east frisian islands of the wadden sea the 1 5 km wide inlet displayed a bathymetric profile consisting of a channel 15 m deep flanked by

three dimensional residual tidal circulation in an elongated rotating basin abstract the three dimensional residual circulation driven by tides in an elongated basin of arbitrary depth is described with a small amplitude constant density model on the f plane the inclusion of rotation fundamentally alters the residual flow with rotation fluid is drawn into the basin on the right side of an observer looking toward the closed end in the northern hemisphere and the return flow is on the opposite side a lateral circulation is superposed on the axial flow with upwelling over the deeper part of each section and downwelling near the sides the residual flow is driven by a combination of advective terms including the lateral advection of axial momentum associated with the coriolis acceleration and stokes forcing tidally averaged fluid parcel trajectories are determined by integrating the lagrangian mean velocities with or without rotation these trajectories vary considerably depending on small differences in initial position as well as on basin shape and other parameters of the

the influence of rock heterogeneity on the scaling properties of simulated and natural stylolites abstract stylolites are among the most prominent deformation patterns in sedimentary rocks that document localized pressure solution recent studies revealed that stylolite roughness is characterized by two distinct scaling regimes the main goal of the present study is to decipher whether this complex scaling behavior of stylolites is caused by the composition of the host rock i e heterogeneities in the material or is governed by inherent processes on respective scales namely the transition from a surface energy to an elastic energy dominated regime as theoretically predicted for this purpose we have developed a discrete numerical technique based on a lattice spring model to simulate the competition between stress strain and dissolution during stylolite roughening we varied systematically the quenched noise initially present in the material which controls the roughening we also changed the size amount and dissolution rate of the heterogeneities introduced in our model and evaluated the influence on the scaling exponents our findings demonstrate that the roughness and growth exponents are independent of the exact nature of the heterogeneities we discovered two coinciding crossover phenomena in space and time that separate length and time scales for which the roughening process is either balanced by surface or elastic energies our observations are consistent with analytical predictions and with investigations quantifying the scaling laws in the morphology of natural stylolites the findings presented here can further be used to refine volume loss compaction estimates from the finite strain pattern of stylolites

stress sensitivity of stylolite morphology abstract stylolites are rough surfaces that form by localized stress induced dissolution using a set of limestone rock samples collected at different depths from a vertical section in cirque de navacelles france we study the influence of the lithostatic stress on the stylolites morphology on the basis of a recent morphogenesis model we measured the roughness of a series of bedding parallel stylolites and show that their morphology exhibits a scaling invariance with two self affine scaling regimes separated by a crossover length l at the millimeter scale consistent with previous studies the importance of the present contribution is to estimate the stylolite formation stress from the sample position in the stratigraphic series and compare it to the crossover length l using the expected relationship l 2 we obtained a successful prediction of the crossover behavior and reasonable absolute stress magnitude estimates using relevant parameters depth of stylolite formation between 300 to 600 m with corresponding normal stress in the range of 10 18 mpa accordingly the stylolite morphology contains a signature of the stress field during formation and we thus suggest that stylolites could be used as paleo stress gauges of deformation processes in the upper crust

spreading direction in the central south china sea recent work1 2 indicates that the south china sea is an atlantictype marginal basin of late tertiary age magnetic anomalies in the eastern part of the sea are consistent with seafloor spreading directed approximately north south1 2 we present here a new morphostructural study based on coupled seabeam mapping and single channel seismic reflection profiling which reveals dominant normal fault scarps striking n50 e between 113 and 119 e longitude near the axis of this basin such a structural fabric implies a nw se spreading direction at least in the 150 200 km wide axial region of the south china sea and places new constraints on geodynamic models for the formation of this basin in the tectonic and palaeogeographic framework of south east asia and the south west pacific

bedding parallel stylolites as a tool to unravel maximum burial depth in sedimentary basins application to middle jurassic carbonate reservoirs in the paris basin france in recent years stylolites which are rough dissolution surfaces commonly found in carbonates have been used for paleopiezometry estimates the stylolite roughness inversion technique srit applied on sedimentary bedding parallel stylolites bps grants access to the maximum principal vertical stress experienced by the host carbonates and thus to their maximum burial paleo depth this study reports the results of srit applied to a bps population hosted in carbonate platform reservoirs of the paris basin sub surface france middle jurassic carbonates from two well cores from the depocenter and margin of the basin for which the burial and thermal history are known based on a thermally calibrated 3 d basin model were analyzed by defining a consistency criterion and using two signal treatment methods we propose a new approach to select which bps can be reliably used to reconstruct the maximum vertical stress undergone by the host carbonates which then can be converted into maximum burial depth the study of a bps population shows that there is a control operated by the host rock texture and the stylolite morphology on the burial depth recorded especially suture and sharp peak bps are better suited to estimate the real maximum depth whereas seismogram pinning bps record preferentially intermediate depths median values of maximum depth derived from our data set 1300 and 1650 m for the margin and depocenter cores respectively are in line with maximum burial estimates provided by conventional basin modeling 1450 and 1800 m respectively thus showing that srit is a standalone robust depth gauge in sedimentary basins provided sample selection and data treatment are carried out in a rigorous and thoughtful manner

growth of stylolite teeth patterns depending on normal stress and finite compaction abstract stylolites are spectacular rough dissolution surfaces that are found in many rock types they are formed during a slow irreversible deformation in sedimentary rocks and therefore participate to the dissipation of tectonic stresses in the earth s upper crust despite many studies their genesis is still debated particularly the time scales of their formation and the relationship between this time and their morphology we developed a new discrete simulation technique to explore the dynamic growth of the stylolite roughness starting from an initially flat dissolution surface we demonstrate that the typical steep stylolite teeth geometry can accurately be modelled and reproduce natural patterns the growth of the roughness takes place in two successive time regimes i an initial non linear increase in roughness amplitude that follows a power law in time up to ii a critical time where the roughness amplitude saturates and stays constant we also find two different spatial scaling regimes at small spatial scales surface energy is dominant and the growth of the roughness amplitude follows a power law in time with an exponent of 0 5 and reaches an early saturation conversely at large spatial scales elastic energy is dominant and the growth follows a power law in time with an exponent of 0 8 in this elastic regime the roughness does not saturate within the given simulation time our findings show that a stylolite s roughness amplitude only captures a very small part of the actual compaction that a rock experienced moreover the memory of the compaction history may be lost once the roughness growth saturates we also show that the stylolite teeth geometry tracks the main compressive stress direction if we rotate the external main compressive stress direction the teeth are always tracking the new direction finally we present a model that explains why teeth geometries form and grow non linearly with time why they are relatively stable and why their geometry is strongly deterministic while their location is random

modeling the growth of stylolites in sedimentary rocks stylolites are ubiquitous pressure solution seams found in sedimentary rocks their morphology is shown to follow two self affine regimes analyzing the scaling properties of their height over their average direction shows that at small scale they are self affine surfaces with a hurst exponent around 1 and at large scale they follow another self affine scaling with hurst exponent around 0 5 in the present paper we show theoretically the influence of the main principal stress and the local geometry of the stylolitic interface on the dissolution reaction rate we compute how it is affected by the deviation between the principal stress axis and the local interface between the rock and the soft material in the stylolite the free energy entering in the dissolution reaction kinetics is expressed from the surface energy term and via integration from the stress perturbations due to these local misalignments the resulting model shows the interface evolution at different stress conditions in the stylolitic case i e when the main principal stress is normal to the interface two different stabilizing terms dominate at small and large scales which are linked respectively to the surface energy and to the elastic interactions integrating the presence of small scale heterogeneities related to the rock properties of the grains in the model leads to the formulation of a langevin equation predicting the dynamic evolution of the surface this equation leads to saturated surfaces obeying the two observed scaling laws analytical and numerical analysis of this surface evolution model shows that the cross over length separating both scaling regimes depends directly on the applied far field stress magnitude this method gives the basis for the development of a paleostress magnitude marker we apply the computation of this marker i e the morphological analysis on a stylolite found in the dogger limestone layer located in the neighborhood of the andra underground research laboratory at bure eastern france the results are consistent with the two scaling regimes expected and the practical determination of the major principal paleostress from the estimation of a cross over length is illustrated on this example

convergence of lateral flow along a coastal plain estuary a set of velocity profiles obtained in the james river estuary with an acoustic doppler current profiler was used in combination with the results of an analytic tidal model to depict the appearance of surface lateral flow convergences v y during both flood and ebb stages of the tidal cycle the bathymetry of the estuary was characterized by a main channel and a secondary channel separated by relatively narrow shoals lateral surface flow convergences appeared over the edges of the channels and were produced by the phase lag of the flow in the channel relative to the shoals flood convergences developed in the late tidal stages and ebb convergences appeared soon after maximum currents most of these convergences caused fronts in the density field and flotsam lines that also appeared over the edges of the channel and that lasted 2 hours the transverse flows associated with the convergences were mostly in the same direction throughout the water column in fact the vertically averaged flow produced the same convergence patterns as those near the surface the analytic tidal model reproduced well the timing and location of the convergences as observed in the james river model results with different bathymetry emulated the results in other estuaries e g axial convergence in an estuary with a channel in the middle this work showed that the strength of lateral convergences along the estuary was proportional to the tidal amplitude and the channel steepness it also suggested that the convergences were produced mainly by the tidal flow interacting with the channel shoal bathymetry i e that they did not require the presence of density gradients however the analytic model underestimated the magnitude of the convergences and did not account for vertical circulations associated with fronts the formation of fronts resulted from the interaction of the tidal flow with the bathymetry and the density field

continental rifting and initial sea floor spreading in the woodlark basin our understanding of the processes by which continents rift and sea floor spreading initiates is derived primarily from studies either of old passive margins and oceanic crust or of young regions of intra continental extension where spreading has not yet started it has been thought that continental rifting ceases when sea floor spreading begins1 2 that oceanic fracture zones develop from transfer or transform faults within continental rifts3 4 and that linear magnetic anomalies correlate with the onset of sea floor spreading during times of magnetic reversals5 6 here we present a marine geophysical survey of one of the few active examples of continental rifting and spreading initiation the western woodlark basin papuan peninsula region of new guinea which shows that in detail these assumptions do not hold the data confirm models of the rifting to spreading transition that invoke both ridge propagation and nucleation of discrete spreading cells7 10 and provide an unambiguous example of a spreading centre reorienting by synchronous jumping rather than propagation

characterization of fault roughness at various scales implications of three dimensional high resolution topography measurements accurate description of the topography of active fault surfaces represents an important geophysical issue because this topography is strongly related to the stress distribution along fault planes and therefore to processes implicated in earthquake nucleation propagation and arrest to date due to technical limitations studies of natural fault roughness either performed using laboratory of field profilometers were obtained mainly from 1 d profiles with the recent development of light detection and ranging lidar apparatus it is now possible to measure accurately the 3 d topography of rough surfaces with a comparable resolution in all directions both at field and laboratory scales in the present study we have investigated the scaling properties including possible anisotropy properties of several outcrops of two natural fault surfaces vuache strike slip fault france and magnola normal fault italy in limestones at the field scale digital elevation models of the fault roughness were obtained over surfaces of 0 25 m2 to 600 m2 with a height resolution ranging from 0 5 mm to 20 mm at the laboratory scale the 3 d geometry was measured on two slip planes using a laser profilometer with a spatial resolution of 20 m and a height resolution less than 1 m

upper bound on stylolite roughness as indicator for amount of dissolution stylolites are rough surfaces that form by localized dissolution despite their abundance in carbonates and sandstones and their importance for fluid flow and rock deformation many fundamental issues concerning their structure and evolution are still unresolved this manuscript studies the roughening of long parallel stylolites here we report measurements of stylolite surface roughness at a scale larger than ever measured before 10 2 10 1 m measurements were performed using ground based lidar on 6 naturally exposed surfaces of 4 km long stylolites in northern israel producing a topographic map of the surfaces from which roughness characteristics were derived our results show that for length scales below 50 cm the stylolite morphology exhibits self affine behavior with a hurst exponent h 0 65 consistent with previous studies made on smaller samples the self affine behavior changes for measurements made on scales above 50 cm with h decreasing almost to zero on long length scales this observed upper bound of self affine roughness is measured here for the first time but has been previously predicted by theory ebner et al 2009b koehn et al 2007 our measurements support these theoretical models and together with them present a scenario in which the investigated stylolites evolve from preferential dissolution along an existing surface that was initially smooth and progressively roughened with time such a mechanism of stylolites growth is different from previously suggested mechanisms for other classes of stylolites which might propagate sideways from an initial defect based on the theoretical roughening model that we adopted the upper limit to fractality for this class of stylolites may be used as a measure of the amount of dissolution on stylolites indeed the amount of dissolution on the stylolites in our field site which we calculated from the upper limit to fractality is comparable to though slightly larger than our estimates of dissolution from two additional independent techniques reflecting compactive strain of 50

stylolites a review abstract stylolites are ubiquitous geo patterns observed in rocks in the upper crust from geological reservoirs in sedimentary rocks to deformation zones in folds faults and shear zones these rough surfaces play a major role in the dissolution of rocks around stressed contacts the transport of dissolved material and the precipitation in surrounding pores consequently they play an active role in the evolution of rock microstructures and rheological properties in the earth s crust they are observed individually or in networks in proximity to fractures and joints and in numerous geological settings this review article deals with their geometrical and compositional characteristics and the factors leading to their genesis the main questions this review focuses on are the following how do they form how can they be used to measure strain and formation stress how do they control fluid flow in the upper crust geometrically stylolites have fractal roughness with fractal geometrical properties exhibiting typically three scaling regimes a self affine scaling with hurst exponent 1 1 0 1 at small scale up to tens or hundreds of microns another one with hurst exponent around 0 5 to 0 6 at intermediate scale up to millimeters or centimeters and in the case of sedimentary stylolites a flat scaling at large scale more complicated anisotropic scaling scaling laws depending of the direction of the profile considered is found in the case of tectonic stylolites we report models based on first principles from physical chemistry and statistical physics including a mechanical component for the free energy associated with stress concentrations and a precise tracking of the influence of grain scale heterogeneities and disorder on the resulting micro structures experimental efforts to reproduce stylolites in the laboratory are also reviewed we show that although micrometer size stylolite teeth are obtained in laboratory experiments teeth deforming numerous grains have not yet been obtained experimentally which is understandable given the very long formation time of such geometries finally the applications of stylolites as strain and stress markers to determine paleostress magnitude are reviewed we show that the scalings in stylolite heights and the crossover scale between these scalings can be used to determine the stress magnitude its scalar value perpendicular to the stylolite surface during the stylolite formation and that the stress anisotropy in the stylolite plane can be determined for the case of tectonic stylolites we also show that the crossover between medium millimetric scales and large pluricentimetric scales in the case of sedimentary stylolites provides a good marker for the total amount of dissolution which is still valid even when the largest teeth start to dissolve which leads to the loss of information since the total deformation is not anymore recorded in a single marker structure we discuss the impact of the stylolites on the evolution of the transport properties of the hosting rock and show that they promote a permeability increase parallel to the stylolites whereas their effect on the permeability transverse to the stylolite can be negligible or may reduce the permeability depending on the development of the stylolite

tidal transformation and resonance in a short microtidal mediterranean estuary alfacs bay in ebre delta abstract tidal and subtidal waves are analyzed with sea level data and numerical modeling in a short and micro tidal embayment alfacs bay nw mediterranean sea data analysis exhibits tidal wave amplification and seiching characteristic period of 3 5 h along the bay numerical results show an eight fold increase in quarter wave resonant wave amplitudes from the mouth to the head of the bay this amplification follows the classical description of a standing wave moreover resonant wave velocities measured and computed at the bay mouth node location are about one order of magnitude higher than tidal currents analysis of astronomic tidal propagation in the bay reveals similar behavior for diurnal and semidiurnal constituents tidal waves amplify along the bay by 3 for diurnal and 10 for semidiurnal constituents numerical simulations conducted with different domains indicate that geometric effects dominate over frictional influences in causing the wave behavior this behavior is consistent with the existence of a quasi steady standing wave within the bay

morphological analysis of stylolites for paleostress estimation in limestones surrounding the andra underground research laboratory site abstract we develop and test a methodology to infer paleostress from the morphology of stylolites within borehole cores this non destructive method is based on the analysis of the stylolite trace along the outer cylindrical surface of the cores it relies on an automatic digitisation of high resolution photographs and on the spatial fourier spectrum analysis of the stylolite traces we test and show on both synthetic and natural examples that the information from this outer cylindrical surface is equivalent to the one obtained from the destructive planar sections traditionally used the assessment of paleostress from the stylolite morphology analysis is made using a recent theoretical model which links the morphological properties to the physical processes acting during stylolite evolution this model shows that two scaling regimes are to be expected for the stylolite height power spectrum separated by a cross over length that depends on the magnitude of the paleostress during formation we develop a non linear fit method to automatically extract the cross over lengths from the digitised stylolite profiles results on cores from boreholes drilled in the surroundings of the andra underground research laboratory located at bure france show that different groups of sedimentary stylolites can be distinguished and correspond to different estimated vertical paleostress values for the oxfordian formation one group of stylolites indicates a paleostress of around 10 mpa while another group yields 15 mpa for the dogger formation two stylolites indicate a paleostress of around 10 mpa while others appear to have stopped growing at paleostresses between 30 and 22 mpa starting at an erosion phase that initiated in the late cretaceous and continues today this method has a high potential for further applications on reservoirs or other geological contexts where stylolites are present

impact of mega scale sand extraction on tidal dynamics in semi enclosed basins an idealized model study with application to the southern north sea long term considerations of repeated and increasing sand extraction on the netherlands continental shelf north sea may lead to the creation of a mega scale extraction trench in front of the dutch coast length hundreds of km width over 10 km depth several m we investigate the impact of such a huge topographic intervention on tidal dynamics which is a key aspect in hydrodynamics and indirectly also affecting morphodynamics and ecology because of the unprecedented extent of the extraction scenario we follow a generic approach aimed at understanding the physical mechanisms behind the changes the orders of magnitude and area of influence hence rather than applying an existing numerical model we develop an idealized model for tide propagation in semi enclosed rectangular basins the model geometry consists of three adjacent compartments with a realistic cross basin depth profile the trench being located in the second compartment while assuming along basin uniformity of depth within each compartment the problem is forced by an incoming kelvin wave the solution in each compartment satisfying the linear depth averaged shallow water equations on the f plane including bottom friction is written as the superposition of semi numerically obtained wave solutions a collocation technique is employed to satisfy no normal flow across the basin s closed end as well as continuity of elevation and flux across the interfaces between the compartments the results indicate changes in tidal range phase and currents throughout the whole basin which shows the importance of a model domain on the scale of the basin changes in coastal tidal range show zones of decrease and increase order cm changes in coastal shore parallel tidal current amplitudes are of the order of cm s 1 a sensitivity analysis for various trench geometries shows that the hydrodynamic impact generally increases with increasing extraction volume being more sensitive to trench depth and width than trench length the changes in tidal currents may structurally alter sediment transport rates with several percents as the bathymetry and coastal morphology result from subtle balances in long term sediment transport the trench may indirectly affect various user functions and values coastal safety navigation marine ecology cables and pipelines and hence be of concern to coastal management

subtidal water flux through a multiple inlet system observations before and during a cold front event and numerical experiments 1 this paper examines the net transport through a multiple inlet bay under a combined force of strong wind and tide with observations and a model experiment the observations were made in central georgia in sapelo and altamaha sounds between 13 and 17 september 2000 wind was weak in the beginning of the survey an air pressure trough as a weak cold front passed the area on 16 september when the wind changed to the northeast and increased in magnitude this front was associated with a midlatitude cyclone in the new england area this weather event with an episode of strong northeasterly winds prompted a numerical model experiment on an idealized three inlet bay with a set of nonlinear 2 d shallow water equations on an f plane which provides some insight to the wind driven circulation under the presence of tidal forcing it is found that tidally induced currents are small compared to wind induced flows when the wind direction is not perpendicular to the alignment of the three inlets the net outward flow tends to occur at the inlet farther away in the downwind direction this is associated with a net inward transport in the inlet opposite of the downwind direction as a result the middle inlet has the minimum of the net flow when the wind is perpendicular to the barrier islands and if the three inlets have different maximum depth values the deeper inlet tends to have a net flow against the wind while the shallower inlet tends to have a net flow in the direction of the wind offshore onshore currents may develop outside of the inlet with outward inward flow as an effect of fluxes through the inlets on the coastal ocean

the permeability of stylolite bearing limestone abstract stylolites are planar features that form due to intergranular pressure solution due to their planar geometry and relative abundance in limestone reservoirs their impact on regional fluid flow has attracted considerable interest we present laboratory permeability data that show that stylolites can be considered as conduits for flow in the stylolite bearing limestones measured a combination of analysis techniques shows that this is due to a zone that surrounds these stylolites that is more porous and contains larger pores than the host rock our data also show that the water permeability of a sample containing a stylolite parallel to fluid flow is typically lower than its permeability to gas explained here as a result of the expansion of minor amounts of clay found in the stylolite and that due to their microstructural similarities tectonic and sedimentary stylolites affect sample permeability similarly finally we show that the permeability anisotropy that develops in the rock mass due to the presence of sedimentary stylolites makes it appear as though the stylolites are acting as barriers to fluid flow and may explain the discrepancy between laboratory measurements and field scale observations this approach can provide estimates for the equivalent permeability and permeability anisotropy for stylolite bearing limestone reservoirs worldwide

the effect of channel length on the residual circulation in tidally dominated channels with an analytic model this paper describes the subtidal circulation in tidally dominated channels of different lengths with arbitrary lateral depth variations the focus is on an important parameter associated with the reversal of the exchange flows this parameter is defined as the ratio between the channel length and one quarter of the tidal wavelength which is determined by water depth and tidal frequency in this study a standard bottom drag coefficient cd 0 0025 is used for a channel with smaller than 0 6 0 7 short channels the exchange flow at the open end has an inward transport in deep water and an outward transport in shallow water this situation is just the opposite of channels with a value larger than 0 6 0 7 long channels for a channel with a value of about 0 35 0 5 the exchange flow at the open end reaches the maximum of a short channel for a channel with a value of about 0 85 1 0 the exchange flow at the open end reaches the maximum of a long channel with the inward flux of water occurring over the shoal area and the outward flow in the deep water area however near the closed end of a long channel the exchange flow appears as that in a short channel that is the exchange flow changes direction along the channel from the head to the open end of the channel for a channel with a value of about 0 6 0 7 the tidally induced subtidal exchange flow at the open end reaches its minimum when there is little flow across the open end and the water residence time reaches its maximum the mean sea level increases toward the closed end for all values however the spatial gradient of the mean sea level in a short channel is much smaller than that of a long channel the differences between short and long channels are caused by a shift in dynamical balance of momentum or equivalently a change in tidal wave characteristics from a progressive wave to a standing wave

propagating rifts crustal extension during continental rifting propagating rifts may not be incompatible with plate tectonic tenets which are considered at the appropriate scale propagation of a rift is a natural consequence of relative motion about a pole of rotation it is not necessarily valid that 1 rifts propagate in one direction or 2 crustal stretching increases with progressive propagation of a rift

tidally driven residual circulation in shallow estuaries with lateral depth variation tidally driven residual circulation in shallow estuaries with lateral depth variation has been studied analytically using a two dimensional depth averaged model the solution is presented for a v shaped channel exchange flow is found to be correlated with the topography the magnitude of this exchange flow depends mainly on four parameters the ratio between the minimum depth on the shoal and the maximum depth in the channel the ratio between the tidal amplitude at the mouth and the mean depth the ratio between the length of the estuary and the tidal wave length and the ratio between the tidal timescale and the decay timescale due to friction generally a net landward flow occurs over the shoals and is balanced by a return flow in the channel the along channel residual velocity changes nearly linearly across the estuary the residual velocity decreases monotonically toward the head of the estuary the transverse residual velocity is convergent in the channel and divergent on the shoals the residual velocity is highly dependent on the length of the estuary when the length of the estuary is much smaller than a quarter of the wave length the residual velocity is relatively small when the length of the estuary is about a quarter of the wave length the magnitude of the residual velocity reaches its maximum when the length of the estuary is much larger than a quarter of the wave length the residual circulation approaches the pattern found in an infinite length estuary on the basis of the analysis of the solution we conclude that exchange flow generated by tides in a shallow estuary is the result of competition among several processes an inward flux is caused by local nonlinearity both in the bottom friction and from propagation of the tidal wave of finite amplitude this inward flux is larger on the shoals and smaller in the channel owing to larger nonlinearity in the shallow water the residual inward flow creates a setup residual surface elevation of water at the head of the estuary that produces a pressure gradient this residual pressure gradient is approximately uniform across the estuary and drives an outward flow that is larger in the channel than on the shoals in all of the parameter space the competition results in a net inflow on the shoals and a net outflow in the channel

tectonic setting of western pacific marginal basins abstract global kinematics as well as magnetic anomalies of marginal basins with continental geology and paleomagnetic data as additional constraints are used to present a set of reconstructions of the western pacific marginal basins between 56 ma and the present at key periods 56 43 32 20 12 and 3 ma our model accounts for the rapid motion of exotic terranes along the whole of the western pacific convergent zone marginal basins appear to open in a great variety of tectonic settings the two extreme examples being the mariana trough where trench suction may be the predominant driving force and the south china sea where intracontinental deformation appears to be the major mechanism the study of marginal basins is a 3 d problem which must take into account the whole tectonic context subduction related tectonics in cross section and upper plate deformation in map view and not only a 2 d problem the classical trench arc back arc problem

friction dominated exchange in a florida estuary abstract the typically observed gravitational circulation in estuaries with lateral variations in bathymetry consists of a combined distribution of vertically and horizontally sheared flows the distribution features inflow at depth and outflow at the surface and along the sides however theoretical results of density driven exchange flows dominated by frictional effects display a laterally sheared distribution with inflow occupying the deepest portion of the cross section and outflow over the shoals the main purpose of this investigation was to obtain observational evidence in support of theoretical results a tidal cycle survey was conducted on february 24 2009 to collect current velocity and hydrographic profile data along a cross estuary transect observations from hillsborough bay were compared qualitatively to numerical model and analytical solution results the observed residual exchange flow pattern compared favorably with the results from a numerical model and an analytical solution that used a condition controlled by friction the relative importance of friction was explored at tidal and subtidal timescales intratidally frictional influences were observed in the spatial distribution of tidal current amplitude and phase as well as in potential energy anomaly stratification variations subtidally frictional influences were observed through the spatial distributions of tidally averaged stratification turbulent kinetic energy dissipation and eddy viscosity values the main finding of this study was that relatively weak tidal currents

variety of stylolites morphologies and statistical characterization of the amount of heterogeneities in the rock the surface roughness of several stylolites in limestones was measured using high resolution laser profilometry the 1d signals obtained were statistically analyzed to determine the scaling behavior and calculate a roughness exponent also called hurst exponent statistical methods based on the characterization of a single hurst exponent imply strong assumptions on the mathematical characteristics of the signal the derivative of the signal or local increments should be stationary and has finite variance the analysis of the measured stylolites shows that these properties are not always verified simultaneously the stylolite profiles show persistence and jumps and several stylolites are not regular with alternating regular and irregular portions a new statistical method is proposed here based on a non stationary but gaussian model to estimate the roughness of the profiles and quantify the heterogeneity of stylolites this statistical method is based on two parameters the local roughness h which describes the local amplitude of the stylolite and the amount of irregularities on the signal m which can be linked to the heterogeneities initially present in the rock before the stylolite formed using this technique a classification of the stylolites in two families is proposed those for which the morphology is homogeneous everywhere and those with alternating regular and irregular portions 2006 elsevier ltd all rights reserved

solutions for subtidal flow in channels and estuaries under different integral constraints this study builds on huntley and ryan 2018 and related prior works on channels and estuaries by considering solutions for the same subtidal dynamics but with alternative integral flow constraints

stylolites porosity depositional texture and silicates in chalk facies sediments ontong java plateau gorm and tyra fields north sea comparison of chalk on the ontong java plateau and chalk in the central north sea indicates that whereas pressure dissolution is controlled by effective burial stress pore filling cementation is controlled by temperature effective burial stress is caused by the weight of all overlying water and sediments as counteracted by the pressure in the pore fluid so the regional overpressure in the central north sea is one reason why the two localities have different relationships between temperature and effective burial stress in the chalk of the ontong java plateau the onset of calcite silicate pressure dissolution around 490 m below sea floor bsf corresponds to an interval of waning porosity decline and even the occurrence of proper stylolites from 830 m bsf is accompanied by only minor porosity reduction because opal is present the pore water is relatively rich in si which through the formation of ca silica complexes causes an apparent super saturation of ca and retards cementation the onset of massive pore filling cementation at 1100 m bsf may be controlled by the temperature dependent transition from opal ct to quartz in the stylolite bearing chalk of two wells in the gorm and tyra fields the nannofossil matrix shows recrystallization but only minor pore filling cement whereas microfossils are cemented cementation in gorm and tyra is thus partial and has apparently not been retarded by opal controlled pore water a possible explanation is that due to the relatively high temperature silica has equilibrated to quartz before the onset of pressure dissolution and thus in this case dissolution and precipitation of calcite have no lag this temperature versus effective burial stress induced difference in diagenetic history is of particular relevance when exploring for hydrocarbons in normally pressured chalk while most experience has been accumulated in the over pressured chalk of the central north sea

modeling the lateral circulation in straight stratified estuaries the dynamics of lateral circulation in an idealized straight estuary under varying stratification conditions is investigated using a three dimensional hydrostatic primitive equation model in order to determine the importance of lateral circulation to the momentum budget within the estuary for all model runs lateral circulation is about 4 times as strong during flood tides as during ebbs this flood ebb asymmetry is due to a feedback between the lateral circulation and the along channel tidal currents as well as to time varying stratification over a tidal cycle as the stratification is increased the lateral circulation is significantly reduced because of the adverse pressure gradient set up by isopycnals being tilted by the lateral flow itself when rotation is included a timedependent cross channel ekman circulation is driven and the tidally averaged bottom lateral circulation is enhanced toward the right bank when looking toward the ocean in the northern hemisphere this asymmetry in the tidally averaged bottom lateral circulation may lead to asymmetric sediment transport leading to asymmetric channel profiles in straight estuaries for the weakly stratified model run advection due to lateral currents is a dominant term in both the along channel and cross channel momentum equations over a tidal cycle and for the tidally averaged momentum equations in the tidally averaged along channel momentum equation lateral advection acts as a driving term for the estuarine exchange flow and can be larger than the along channel pressure gradient therefore it should not be ignored when estimating momentum budgets in estuaries

recent and future trends in paleopiezometry in the diagenetic domain insights into the tectonic paleostress and burial depth history of fold and thrust belts and sedimentary basins paleopiezometry provides an access to the past stress magnitude key to better understand the behaviour of the earth s crust over long period of time this contribution presents a review of some paleopiezometric techniques that can be used in the diagenetic domain in fold and thrust belts and sedimentary basins calcite twinning and stylolite roughness techniques have been selected and are presented through a critical description of their methodologies along with approaches to further reconstruct the complete effective stress tensor major geological lessons learned over the past decades from published studies are summarized and discussed along with a way forward to potential breakthroughs

thermal weakening of the carbonate basement under mt etna volcano italy implications for volcano instability abstract the physical integrity of a sub volcanic basement is crucial in controlling the stability of a volcanic edifice for many volcanoes this basement can comprise thick sequences of carbonates that are prone to significant thermally induced alteration these debilitating thermal reactions facilitated by heat from proximal magma storage volumes promote the weakening of the rock mass and likely therefore encourage edifice instability such instability can result in slow gravitational spreading and episodic to continuous slippage of unstable flanks and may also facilitate catastrophic flank collapse understanding the propensity of a particular sub volcanic basement to such instability requires a detailed understanding of the influence of high temperatures on the chemical physical and mechanical properties of the rocks involved the juxtaposition of a thick carbonate substratum and magmatic heat sources makes mt etna volcano an ideal candidate for our study we investigated experimentally the effect of temperature on two carbonate rocks that have been chosen to represent the deep heterogeneous sedimentary substratum under mt etna volcano this study has demonstrated that thermal stressing resulted in a progressive and significant change in the physical properties of the two rocks porosity wet i e water saturated dynamic poisson s ratio and wet vp vs ratio all increased whilst p and s wave velocities bulk sample density dynamic and static young s modulus dry vp vs ratio and dry dynamic poisson s ratio all decreased at temperatures of 800 c the carbonate in these rocks completely dissociated resulting in a total mass loss of about 45 and the release of about 44 wt of co 2 uniaxial deformation experiments showed that high in situ temperatures 500 c significantly reduced the strength of the carbonates and altered their deformation behaviour above 500 c the rocks deformed in a ductile manner and the output of acoustic emissions was greatly reduced we speculate that thermally induced weakening and the ductile behaviour of the carbonate substratum could be a key factor in explaining the large scale deformation observed at mt etna volcano our findings are consistent with several field observations at mt etna volcano and can quantitatively support the interpretation of 1 the irregularly low seismic velocity zones present within the sub volcanic sedimentary basement 2 the anomalously high co 2 degassing observed 3 the anomalously high vp vs ratios and the rapid migration of fluids and 4 the increasing instability of volcanic edifices in the lifespan of a magmatic system we speculate that carbonate sub volcanic basement may emerge as one of the decisive fundamentals in controlling volcanic stability