empirical relationships among seismic velocity effective pressure porosity and clay content in sandstone we use a multivariate analysis to investigate the influence of effective pressure pe porosity and clay content c on the compressional velocity vp and shear velocity vs of sandstones laboratory measurements on water saturated samples of 64 different sandstones provide a large data set that was analyzed statistically for each sample relationships between effective pressure and vp and vs have been determined all samples were well fit by relationships that have an exponential increase in velocity at low pe tapering to a linear increase with pe for pe greater than 0 2 kbar there are differences in the pressure dependences of velocity for different rocks particularly at very low pressures however the differences cannot be attributed to or c for the combined set of measurements from all samples the best fitting formulations are vp 5 77 6 94 1 73c 0 446 pe e 16 7pe and vs 3 70 4 94 1 57c 0 361 pe e 16 7pe while this is admittedly a very simplified parameterization it is remarkable how well

a facies model for internalites internal wave deposits on a gently sloping carbonate ramp upper jurassic ricla ne spain abstract internal waves are waves that propagate along the pycnocline the interface between two density stratified fluids even though internal waves are ubiquitous in oceans and lakes their impact in the sedimentary record has remained largely unrecognized internal waves can remobilize the sediment from the depth at which the internal waves break onto the sea floor in shelf or ramp settings internal wave deposits internalites have to be distinguished from tempestites while in slope and deeper settings internalites require distinction from turbidites the upper kimmeridgian carbonate ramp succession cropping out near ricla ne spain provides some key evidence to differentiate the depositional processes induced by breaking internal waves from those related to surface storm waves sandy oolitic grainstone eventites previously interpreted as tempestites contain evidence of reworking by turbulent events related to breaking internal waves underlying rationale are 1 they occur in distal mid ramp position detached from the coeval shallow water successions 2 they do not have the characteristic coarsening and thickening upward trend of storm deposits 3 they gradually thin out to disappear both up dip and down dip interbedded with mid ramp lime mudstones and 4 they show little or no erosion towards the shallower areas a facies model for internalites produced by two sediment populations sand and mud on a gently sloping carbonate ramp is proposed the individual internalites occurring at ricla include several architectural elements sequentially organized in dip direction which can be related to the flows associated with breaking internal waves erosion in the breaker zone swash run up and tractive backwash flow individual internalites stack with down and up slope shingling configuration in dm thick packages thought to reflect the up slope and down slope migration of the breaker zone in turn related to depth variations of the palaeo pycnocline packages occur in dm to m thick clusters suggested to reflect changes in sediment supply and or variations in water stratification affecting the energy of internal waves

sandstone vs carbonate petroleum reservoirs a global perspective on porosity depth and porosity permeability relationships plots are presented comparing average porosity vs depth for 30 122 siliciclastic petroleum reservoirs and 10 481 carbonate petroleum reservoirs covering all petroleum producing countries except canada however separate plots cover 5534 siliciclastic and 2830 carbonate reservoirs of the alberta basin in canada average permeability vs average porosity is shown for the non canadian reservoirs key similarities and differences between sandstones and carbonates are noted and implications are discussed regarding the dominant factors controlling reservoir quality in each lithology trends of steadily decreasing median and maximum porosity with increasing depth reflect burial diagenetic porosity loss in response to increasing thermal exposure with depth these trends seem inconsistent with the suggestions that both sandstones and carbonates commonly increase in porosity by dissolution during deeper burial carbonate reservoirs have lower values of median and maximum porosity for a given burial depth probably because of greater chemical reactivity of carbonate minerals relative to quartz and the resulting lower resistance to chemical compaction and associated cementation relative paucity of low porosity 0 8 siliciclastic reservoirs at all depths compared with carbonates may reflect the more common occurrence of fractures in carbonates and the effectiveness of these fractures for facilitating economic flow rates in low porosity rock overall carbonate reservoirs do not have lower permeability for a given porosity compared with sandstones but do have strikingly lower proportions of both high porosity and high permeability values the data presented can serve as a general guide for the distribution of reservoir quality that can reasonably be expected in exploration wells drilled to any given depth in the absence of detailed geologic information such as burial and thermal history

gassmann s fluid substitution and shear modulus variability in carbonates at laboratory seismic and ultrasonic frequencies carbonates have become important targets for rock property research in recent years because they represent many of themajoroilandgasreservoirsintheworld someareundergoing enhanced oil recovery most laboratory studies to understand fluid and pressure effects on reservoir rocks have been performed on sandstones but applying relations developed for sandstones to carbonates is problematic at best we measure in the laboratory nine carbonate samples from the same reservoir at seismic 3 3000 hz and ultrasonic 0 8 mhz frequencies samples are measured dry humidified and saturated with liquid butane and brine our carbonate samples showed typical changes in moduli as a function of porosity andfluid saturation however we explore the applicability of gassmann s theory on limestone and dolomite rocks in the context of shear and bulk modulus dispersion andgassmann stheoryassumptions forourcarbonatesetat high differential pressures and seismic frequencies the bulk modulus of rocks with high aspect ratio pores and dolomite mineralogy is predicted by gassmann s relation we also explore in detail some of the assumptions of gassmann s relation especiallyrock framesensitivitytofluidsaturation our carbonate samples show rock shear modulus change from dry to brine saturation conditions and we investigate several rock fluid mechanisms responsible for this change to our knowledge these are the first controlled laboratory experimentsoncarbonatesintheseismicfrequencyrange

what does hydraulic tomography tell us about fractured geological media a field study and synthetic experiments abstract between 2005 and 2010 japan atomic energy agency conducted four long term independent pumping tests in a fractured granite formation at the mizunami underground research laboratory miu site in mizunami city central japan during these tests drawdowns were monitored at different depths along several deep boreholes these tests become one of the few if not the only hydraulic tomographic survey conducted in the world over thousands of meters in a fractured geologic medium with several fault zones we analyzed the drawdown time data set associated with each pumping test independently and then the data sets from all pumping tests jointly to derive the spatial distributions of hydraulic conductivity k and specific storage s s of the medium these estimated distributions revealed some large scale high k and low k zones while the low k zones corroborated well with known low permeable layers and fault based on geological investigations there were no clear geological features that can be related to the large scale high k zones in order to understand and substantiate these high and low k zones we simulated a hydraulic tomographic survey in a synthetic fractured aquifer which bears similar geologic features i e formations fractures and faults at the miu site with exception that the hydraulic properties fracture and fault distributions were known exactly results of the simulation show that not only are the identified high k zones related to fracture networks connected with pumping and observation locations of each pumping test but also their values reflect the degree of connectivity of the network afterward we investigated the extent of the improvement of characterization of the fault and fractures through the use of deploying dense monitoring intervals and late time flux measurements

critical porosity and elastic properties of microporous mixed carbonate siliciclastic rocks by integrating elastic property measurements and quantitative mineralogic and petrographic analyses of 45 mixed carbonate siliciclastic samples from two wells drilled in late cretaceous rock of the south provence basin southeast france we can 1 identify and quantify the parameters controlling elastic properties 2 demonstrate that micrite can be considered as a porous medium with a low critical porosity averaging 18 and 3 relate diagenetic transformations pore structure modifications and elastic property changes microporous carbonates with compact anhedral and euhedral microrhombic micrites display a steeper decrease in compressional and shear velocities with increasing porosity than do carbonate rocks with moldic intergranular or intercrystalline macroporosity the low value of critical porosity estimated in micrites 18 as well as the steep slopes of velocity porosity relationships at low porosity is believed to result from a pore network geometry characterized by very flat thin pores bounded by planar faces of micrite crystals cementation of microrhombic micrite steeply increases elastic moduli whereas dissolution processes significantly increase porosity with low variations of elastic moduli thus critical porosity concepts can help describe and model elastic properties of micritic microporous carbonate

controls on acoustic properties of upper jurassic siliciclastic rocks boulonnais northern france more than 200 plugs from outcrop and a nearby borehole in a carbonaceous siliciclastic interval of late jurassic kimmeridgian to tithonian age were quantitatively analyzed for texture mineralogy and acoustic properties our primary goal was to study the effect of clay fraction smaller than 8 m silt sand fraction larger than 8 m and carbonate on the acoustic properties the quantitative nature and volume of the data made it possible to observe four dimensional relationships in contoured ternary diagrams primary control on the acoustic properties is exerted by porosity but the trend of this relationship significantly deviates from popular velocity transforms the contribution of clay silt sand and carbonate particular material and cement explains the remaining variation in acoustic properties although no clear linear thresholds are defined a general trend is that clay and carbonate content have opposite and overlapping effects on acoustic properties the influence of clay content progressively increases with decreasing carbonate content and visa versa with increasing carbonate content the variation of acoustic velocity at a given porosity value increases to nearly twice of that in the clay dominated sediment traditional classification boundaries are present but strongly overprinted by this interplay between clay and carbonate this study may have important implications for porosity and lithofacies prediction from wireline logs in similar mixtures of sediment in addition the quantitative character of the textural and mineralogical data may provide a direct link from acoustic properties to the primary depositional system and sequence stratigraphy

quantitative characterization of carbonate pore systems by digital image analysis a new method of digital image analysis can quantify pore parameters over more than three orders of magnitude from a submicron to a millimeter scale this porosity characterization does not require knowledge of lithology age burial depth or diagenesis of the sample the method is based on digital analyses of images from thin sections at variable magnifications taken under an optical microscope om and under an environmental scanning electron microscope esem the results help explain variations in permeability for carbonate samples with a variety of complex pore structures the analyses however can be done on any thin sections of other rock types the om images provide macroporosity information whereas the esem images yield information on microporosity the boundary between macroporosity and microporosity is defined at a pore area of 500 m2 which translates to a pore length of approximately 20 m which is roughly the thickness of a thin section and thus the resolution of the om the digitized thin section images are binarized into a macropore and a matrix phase om or a micropore and a solid phase esem a standard digital image analysis program is used to detect all individual pores and to measure pore area and pore perimeter based on these analyses one can calculate for each sample the amount of macroporosity the amount of microporosity within the matrix intrinsic microporosity the shapes of the macropores perimeter over area and the pore size distribution comparison of total porosity determined from plugs indicates that macroporosity and microporosity values based on this methodology match the plug data confirming the validity of the method the combination of macroporosity and microporosity data yields pore size distribution and pore shape information that can explain the distribution of physical properties in particular permeability in parameter sensitivity analyses using neural networks permeability appears to be mainly controlled by the macropore shape in high permeability samples and by the amount of intrinsic microporosity in the low permeability samples

controls on sonic velocity in carbonates compressional and shear wave velocities v p and v s of 210 minicores of carbonates from different areas and ages were measured under variable confining and pore fluid pressures the lithologies of the samples range from unconsolidated carbonate mud to completely lithified limestones the velocity measurements enable us to relate velocity variations in carbonates to factors such as mineralogy porosity pore types and density and to quantify the velocity effects of compaction and other diagenetic alterations

holocene sea level change on the southeast coast of australia a review a revised holocene sea level curve for the southeast coast of new south wales australia is presented based on a review of previously published geochronological results for fossil molluscs organi

aquifer heterogeneity characterization with oscillatory pumping sensitivity analysis and imaging potential 1 periodic pumping tests in which a fluid is extracted during half a period then reinjected have been used historically to estimate effective aquifer properties in this work we suggest a modified approach to periodic pumping test analysis in which one uses several periodic pumping signals of different frequencies as stimulation and responses are analyzed through inverse modeling using a steady periodic model formulation we refer to this strategy as multifrequency oscillatory hydraulic imaging oscillating pumping tests have several advantages that have been noted including no net water extraction during testing and robust signal measurement through signal processing through numerical experiments we demonstrate additional distinct advantages that multifrequency stimulations have including 1 drastically reduced computational cost through use of a steady periodic numerical model and 2 full utilization of the aquifer heterogeneity information provided by responses at different frequencies we first perform fully transient numerical modeling for heterogeneous aquifers and show that equivalent results are obtained using a faster steady periodic heterogeneous numerical model of the wave phasor the sensitivities of observed signal response to aquifer heterogeneities are derived using an adjoint state based approach which shows that different frequency stimulations provide complementary information finally we present an example 2 d application in which sinusoidal signals at multiple frequencies are used as a data source and are inverted to obtain estimates of aquifer heterogeneity these analyses show the different heterogeneity information that can be obtained from different stimulation frequencies and that data from several sinusoidal pumping tests can be rapidly inverted using the steady periodic framework

acoustic behavior of sedimentary rocks geologic properties versus poisson s ratios velocity transforms are essential for the extraction of geologic information from seismic reflection data sets and or predicting porosity from wireline logging data most commonly used transforms like the wyllie time average equation the raymer modified time average equation and the gardner equation are all based on empirical relationships extracted from relatively small clean mono and bimineral and mostly siliciclastic data sets and generally fail to explain the acoustic relationships within multimineral data sets to extract globally significant relationships between geologic and acoustic parameters more than 2800 plug measurements were collected more than two thirds of the data were our own measurements the others were from the literature this data set covers nearly all sedimentary environments and mixtures of those as well as the entire range in petrophysical properties

palaeogeographical significance of the triassic jurassic unconformity in the north iberian basin sierra del moncayo spain abstract field work carried out on the lower jurassic i e hettangian lower pliensbachian of the north iberian basin sierra del moncayo spain including the mapping of unconformities and sedimentary units as well as the facies analysis has allowed us to recognize two episodes in the sedimentary evolution of the basin a lower one hettangian in age includes sediments deposited during the period of extensional tectonic activity which involved the formation of half graben basins by normal listric faults sedimentary breccias and rudites located mainly at the edges of the half grabens are derived from the erosion of blocks uplifted during the triassic in the depocenter of the half grabens which show most subsidence these breccias pass into thick dolomitic and evaporitic successions deposited in sabkha environments under negligible marine influence the later episode sinemurian and lower pliensbachian in age consists of shallow marine carbonate units deposited in a low angle ramp setting evaporite accumulation took place during phases of relative lowstand of sea level i e lowstand systems tract when the basin was cut ooff from open marine conditions whereas the carbonate sediments mainly represent transgressive and highstand systems tracts in the iberian basin the lowstand episode during the hettangian was mainly induced by the breakup of the upper triassic ramp which favoured the isolation from open marine conditions of several subsident sub basins in addition it should be noted that the hettangian is considered as a lowstand sea level episode in some of the proposed global eustatic cycle charts so that a eustatic component may also be postulated for the isolation of the basin at this time the infilling of the hettangian half grabens left an even topography which was flooded during the sinemurian sea level rise leaving shallow carbonate deposits the results presented here give new information on the paleogeography of northeast iberia at the triassic jurassic boundary in the context of the opening of the western margin of the tethys

pore space evolution and elastic properties of platform carbonates urgonian limestone barremian aptian se france abstract a dataset of 214 ultrasonic velocity and porosity measurements on barremian aptian carbonates from provence se france provides well constrained velocity porosity transforms and allows the quantification of the impact of pore type and diagenetic history on these velocities a numerical approach epar equivalent pore aspect ratio was used to link diagenetic transformations pore network evolution and elastic properties three categories of samples characterized by their dominant pore type were discriminated from the velocity and porosity database by means of the epar values derived from bulk k epar and shear epar moduli 1 purely microporous limestones low k and epar 0 3 three velocity porosity trajectories related to three diagenetic paths were defined and quantified from the urgonian database 1 epar preserving micro scale cementation of micrite 2 non epar preserving dissolution with moldic pore development and 3 epar preserving sparry calcite cementation of molds equivalent pore aspect ratio can therefore be regarded as a robust tool to decipher diagenetic trends in velocity porosity transforms and may help predicting pore architecture from subsurface data

periodic pumping tests summary we performed pumping tests with a periodic succession of injection and production intervals in a field of three shallow boreholes penetrating a jointed sandstone formation tests were conducted at periods ranging from 10 to 5400 s and pumping rates between 5 and 20 l min 1 two types of analysis for the periodic pumping tests are presented injectivity analysis rests on the determination of the amplitude ratio and phase shift between the periodic flow rate and pressure records from the pumping well interference analysis is based on an evaluation of attenuation and phase shift between the periodic pressure signals at the pumping and monitoring wells a periodic excitation permits to employ standard signal processing tools such as fast fourier transformation facilitating the evaluation of weak signals the observed amplitude ratio and phase shift values are compared to analytical predictions of 1 d and radial flow models results of interference tests are particularly diagnostic for the applicability of a subsurface model our test results do not fully agree with any of the considered analytical models suggesting a heterogeneous subsurface we suppose that the two analysis methods yield averaged hydraulic properties of different volumes of a heterogeneous subsurface periodic injectivity tests screen the subsurface to increasing penetration depth if pumping period is systematically increased while the subsurface volume between pumping and monitoring well dominates the outcome of an interference test at all periods periodic pumping provides several operational advantages compared to conventional testing such as drawdown pulse or shut in tests periodic testing can be superposed on a long term operation reducing operational conflicts and permitting continuous monitoring of changes in subsurface properties processing of periodic signals provides results even in a field with strong transient changes in fluid pressure related for example to operations in nearby wells periodic pumping can be performed in a closed loop minimizing the total fluid volume involved

seismic expression of channel outcrops offset stacked versus amalgamated channel systems abstract forward seismic models of two seismic scale outcrops of different style channel systems have been made to investigate their seismic signature these two outcrops illustrate the geometric end members of channel stacking architecture in response to low and high accommodation space the eocene nohut tepe channel system of the elazig basin in eastern turkey was deposited in an area of high accommodation resulting in an aggradational geometrical offset stacking of channels up against a slope the eocene ainsa ii channel system of the tremp pamplona basin in the spanish pyrenees was deposited in an area of low accommodation resulting in a tabular compound sheet geometry with amalgamated channel bodies separated by clay drapes depth models were drawn from outcrop photos and converted to impedance models by assigning acoustic impedance properties to the sand filled channels and surrounding and interbedded mud and clay layers these were the input for the forward seismic models which constructed various frequency synthetic seismic sections of the two outcrops analysis of the outcrop synthetic seismic identified three distinct reflection configurations type i is characterised by a strong black peak and white trough reflection which is due to a discrete channel body type ii is characterised by multiple offset time stepped black peak reflections that are underlain by one continuous strong white trough reflection which is due to offset stacked channel bodies type iii is characterised by strong black peaks which onlap an underlying continuous white trough reflection caused by the lateral amalgamation of channel bodies these three types of reflection configurations observed on the outcrop synthetic seismic can also be found on actual seismic from channelised turbidite systems which aids in interpreting channel stacking architecture accommodation space prediction and depositional styles from the actual seismic data channel stacking architecture is clearly an important aspect which needs to be considered when making channel system interpretations based on seismic data

aquifer imaging with pressure waves evaluation of low impact characterization through sandbox experiments understanding the detailed spatial variation of hydraulic properties in the subsurface has been the subject of intensive research over the past three decades a recently developed approach to characterize subsurface properties is hydraulic tomography in which a series of pumping tests are jointly inverted using a heterogeneous numerical model recently cardiff et al 2013 proposed a modified tomography approach named oscillatory hydraulic tomography oht in which periodic pumping signals of different frequencies serve as the aquifer stimulation and pressure responses are recorded at observation locations for tomographic analysis its key advantages over traditional hydraulic tomography are that 1 there is no net injection or extraction of water and 2 the impulse an oscillatory signal of known frequency is easily extracted from noisy data however oht has only been evaluated through numerical experiments to date in this work we evaluate oht performance by attempting to image known heterogeneities in a synthetic aquifer an instrumented laboratory sandbox is filled with material of known hydraulic properties and we measure aquifer responses due to oscillatory pumping stimulations at periods of 2 5 10 and 20 s pressure oscillation time series are processed through fourier transforms and inverted tomographically to obtain estimates of aquifer heterogeneity using a fast steady periodic groundwater flow model we show that oht is able to provide robust estimates of aquifer hydraulic conductivity even in cases where relatively few pumping tests and observation locations are available the use of multiple stimulation frequencies is also shown to improve imaging results

changes of shear moduli in carbonate rocks implications for gassmann applicability in laboratory experiments we measured the saturation effects on the acoustic properties in carbonates and the results question some theoretical assumptions in particular these laboratory experiments under dry and wet conditions show that shear moduli do not remain constant during saturation this change in shear modulus puts gassmann s assumption of a constant shear modulus into question and also explains why velocities predicted with the gassmann equation can be lower or higher than measured velocities

petrophysical imaging using avo seismic lithology is the process by which rock properties such as lithology porosity and pore fluid content are determined by analysis of seismic and other data i emphasize other data because the seismic method is limited in what can be achieved in a vacuum but can be remarkably robust when combined with other information and constrained by geologically reasonable assumptions i define petrophysical imaging as a seismic lithology method which does not attempt to recover absolute rock properties but rather involves the construction of an image of subsurface rock property variation for example for direct hydrocarbon indication absolute rock properties need not be determined only the deviation from background nonpay behavior is required

evaluation of a numerical model of the british irish ice sheet using relative sea level data implications for the interpretation of trimline observations the glacial isostatic adjustment gia of the british isles is complex due to the interplay between local and non local signals a number of recent studies have modelled the gia response of the british isles using relative sea level data this study extends these previous analyses by using output from a numerical glaciological model as input to a gia model this is a necessary step towards more realistic gia models and although there have been similar studies for the major late pleistocene ice sheets this is the first study to do so for the british isles we test three reconstructions classed as minimal median and maximal in terms of their volume at maximum extent and find it is possible to obtain good data model fits the minimal reconstruction is clearly preferred by the sea level data the ice reconstructions tested were not constrained by geomorphological information of past ice extent lateral and vertical as a consequence the reconstructions extend further than much of this information suggests particularly in terms of ice thickness it is notable however that the reconstructions produce good fits to many sea level data from central mountainous regions e g scottish highlands which lends support to the suggestion that trimlines often used as an constraint on the palaeo ice surface location are in fact features formed at the transition from warm to cold based ice and so mark a minimum constraint on the ice surface altitude based on data model misfits suggestions are made for improving the ice model reconstructions however in many locations the cause of the misfit could be due to non local predominantly fennoscandian ice and so interpretation is not straightforward as a result we suggest that future analyses of this type consider models and observations for both fennoscandia and the british isles copyright 2012 john wiley sons ltd

effects of diagenesis and clays on compressional velocities in rocks experimental results at ultrasonic frequencies in brine or water saturated samples cut perpendicular to bedding demonstrate that compressional velocities vary linearly with porosity and volume fraction clay in detrital silicate rocks characterized by pores with low aspect ratios p wave velocity is more sensitive to porosity than clay content obeying the empirically derived expression vp 2 4c 8 6 5 8 at 800 bars confining pressure and 400 bars pore pressure where the units of vp are kilometers per second is the volume fraction pores and c is the volume fraction clay deviations from this equation are less than 2 with the exception of the high pore aspect ratio st peter sandstone which has a compressional velocity that is 17 higher than the predicted value the equation is insensitive to the chemical compostion of the dominant clay mineral and apparently insensitive to the location of the clay grains with respect to the mineral framework e g in free pore space or in contact zones between mineral grains of lower compressibilities

determination of hydrogeological parameters using sinusoidal pressure tests a theoretical appraisal a method for determining the hydrogeologic parameters of formations of interest based on a sinusoidal pressure fluctuation in an excitation borehole is proposed equations are derived which describe the dependence of pressures and phase lags outside the excitation borehole on distance signal frequency specific storage hydraulic conductivity and flow rates these cover 2 distinct configurations that of a point source deep within a water saturated elastic formation and that of a line source totally penetrating a confined aquifer the ranges of application of these 2 arrangements are appraised using existing data on hydraulic diffusivities to derive likely excitation and response pressures for various flow rates and signal frequencies the 2 configurations require the accurate measurement of phase shifts in the case of the point source and of amplitude in the line source case and it is concluded that the ranges of applications are useful but limited 20 references

transgressive regressive cycles and jurassic palaeogeography of northeast iberia abstract a correlation and sequence stratigraphy study of jurassic successions has been carried out in the main sedimentary basins of northeast iberia i e asturias basque cantabrian and iberian basins based on the identification of transgressive regressive cycles the development and palaeogeographic evolution of the epicontinental carbonate platforms of northeast iberia were largely controlled by major tectonic activity at three main intervals at the beginning of the jurassic in the lower middle jurassic transition and during the uppermost jurassic respectively during early jurassic times northeast iberia was the site of a single and large carbonate ramp opened to the north this carbonate ramp suffered a progressive drowning evolving from an inner to hemipelagic ramp systems with the local development of suboxic environments in the deepest areas located to the north during the middle jurassic different open carbonate platforms were formed including the development of swells in intermediate areas during the upper jurassic the outer ramp areas were progressively moving to the east iberian basin and the ammonite faunas showing a markedly tethyan affinity thereafter three first order t r cycles bounded by major discontinuities associated with significant time gaps are identified they extend respectively from the latest rhaetian to the early aalenian from the middle aalenian to the early oxfordian and from the early oxfordian to the late berriasian major transgressive peaks occurred at the middle toarcian bifrons zone at the late bajocian upper niortense and garantiana zones and at the mid kimmeridgian divisum zone each of the first order cycles includes four second order t r cycles cycles 1 1 1 4 are identified in the northern basins cycles 2 1 2 4 display some differences in age of transgressive peaks from one basin to another cycles 3 1 3 4 are mainly identified in the iberian basin the correlation with other separated boreal and thethysian basins demonstrates that the number and age of t r cycles varies from one basin to another and are mainly controlled by the local or regional tectonic development the transgressive peaks may reflect episodes of eustatic rise during the jurassic however their different age from one basin to another is explained by different subsidence evolution

a hybrid dimensional approach for an efficient numerical modeling of the hydro mechanics of fractures characterization of subsurface fluid flow requires accounting for hydro mechanical coupling between fluid pressure variations and rock deformation particularly flow of a compressible fluid along compliant hydraulic conduits such as joints fractures or faults is strongly affected by the associated deformation of the surrounding rock we investigated and compared two alternative numerical modeling approaches that describe the transient fluid pressure distribution along a single deformable fracture embedded in a rock matrix first we analyzed the coupled hydro mechanical problem within the framework of biot s poroelastic equations second in a hybrid dimensional approach deformation characteristics of the surrounding rock were combined with a one dimensional approximation of the fluid flow problem to account for the high aspect ratios of fractures and the associated numerical problems a dimensional analysis of the governing equations reveals that the occurring physical phenomena strongly depend on the geometry of the hydraulic conduit and on the boundary conditions for the analyzed geometries hydro mechanical coupling effects dominate and convection effects can be neglected numerical solutions for coupled hydro mechanical phenomena were obtained and compared to field data to characterize the fractured rock in the vicinity of an injection borehole either approach captures convection diffusion and hydro mechanical effects yet the hybrid dimensional approach is advantageous due to its applicability to problems involving high aspect ratio features for such cases the modeling of pumping tests by means of the hybrid dimensional approach showed that the observed inverse pressure responses are the result of the coupling between the fluid flow in the fracture and the rock deformation caused by fluid pressure variations along the fracture storage capacity as a single parameter of a fracture is insufficient to address all aspects of the coupling

a coupled inversion of pressure and surface displacement a coupled inversion of transient pressure observations and surface displacement measurements provides an efficient technique for estimating subsurface permeability variations the methodology has the advantage of utilizing surface observations which are typically much less expensive than measurements requiring boreholes furthermore unlike many other geophysical observables the relationship between surface deformation and reservoir pore fluid volume changes is relatively well understood our treatment enables us to partition the estimation problem into a sequence of three linear subproblems an application of the approach to a set of tilt and borehole pressure data from the raymond field site in california illustrates its efficiency and utility the observations are associated with a well test in which fluid is withdrawn from a shallow fracture zone during the test 13 tiltmeters recorded the movement of the ground surface simultaneously nine transducers measured pressure changes in boreholes intersecting the fracture system we are able to image a high permeability north trending channel located within the fracture zone the existence and orientation of this high permeability feature is substantiated by a semiquantitative analysis of some 4000 transient pressure curves

effects of microporosity on sonic velocity in carbonate rocks the elastic moduli of a rock are affected by three main factors pore fluid rock framework and pore space in carbonate rocks the latter two factors are a function of the depositional environment and the diagenetic history cementation recrystallization and dissolution processes can change the mineralogy and texture of the original framework and thereby alter the original grain to grain contacts and or occlude pore space dissolution processes can enlarge interparticle pore space or dissolve grains entirely thereby increasing porosity these diagenetic alterations and associated changes in the rock frame and pore structure result in a wide velocity range at a given porosity

ground penetrating radar response to fracture fluid salinity why lower frequencies are favorable for resolving salinity changes time lapse ground penetrating radar gpr surveys exploit signal amplitude changes to monitor saline tracers in fractures and to identify groundwater flow paths however the relationships between gpr signal amplitude phase and frequency with fracture aperture and fluid electrical conductivity are not well understood we used analytical modeling numerical simulations and field experiments of multifrequency gpr to investigate these relationships for a millimeter scale aperturefracturesaturatedwithwaterofvaryingsalinity we found that the response of lower frequency radar signals detects changes in fluid salinity better than the response of higher frequency signals increasing fluid electrical conductivity decreases low frequency gpr signal wavelength which improves its thin layer resolution capability we concluded that lower signal frequencies such as 50 mhz and saline tracers of up to 1 s m conductivity are preferablewhenusinggprtomonitorflowinfracturedrock furthermore we found that gpr amplitude and phase responsesaredetectableinthefieldandpredictablebyemtheory and modeling therefore they can be related to fracture aperture and fluid salinity for hydrologic investigations of fractured rockflowandtransportproperties

on the use of apparent hydraulic diffusivity as an indicator of connectivity summary connectivity of high permeability paths is recognized as important but has not been properly quantified in the groundwater literature in fact it has been shown that the concept is process dependent and difficult to define so that it applies both to water flow and solute transport phenomena field and numerical evidence from hydraulic tests suggest that the apparent hydraulic diffusivity d a could potentially inform about the phenomena in order to test this conjecture we present a monte carlo analysis based on series of fields that display varying degrees of connectivity our results confirm that d a does indeed indicate the presence of connectivity d a is found to correlate well with early tracer arrival time and also with the product of a flow connectivity indicator cf and a transport connectivity indicator ct this indicates that d a accounts both for connectivity effects controlling the average plume movement through cf and for connectivity effects not linked to the effective medium properties that control the progression of the solute front through ct analysis of seven binary fields suggests that flow connectivity hinges more on the continuity of fast paths whereas transport connectivity seems to be more dependent on the width of connected features forming possibly discontinuous fast paths in conjunction with previous studies our results suggest that hydraulic response arrival times and early arrival times of tracer can be expected to correlate well in most types of hydrogeologic systems

parameters controlling sonic velocities in a mixed carbonate siliciclastics permian shelf margin upper san andres formation last chance canyon new mexico we have measured the acoustic properties and mineralogic composition of 48 rock specimens from mixed carbonate siliciclastic outcrops of the permian upper san andres formation in last chance canyon new mexico the goals were 1 identify and model the parameters controlling the sonic velocities 2 assess the influence of postburial diagenesis on the acoustic velocities the variation in sonic velocity in the 0 to 25 porosity range is primarily controlled by porosity and secondly by the ratio of carbonate siliciclastic material linear multivariate fitting resulted in a velocity porosity carbonate content transform that accurately predicts sonic velocity at different effective stresses the slope of the velocity porosity transform steepens with increasing carbonate content which may be explained by the higher velocity of carbonate minerals another reason may be the property of carbonate minerals to form more perfect intercrystalline boundaries that improve the transmission properties of acoustic waves and are less sensitive to changes in effective stress the velocity ratio vp vs is an excellent tool to discriminate between predominantly calcitic lithologies ratio between 1 8 and 1 95 and predominantly dolomitic and quartz rich lithologies ratio between 1 65 and 1 8 gardner s experimental curve overestimates and the velocity porosity transforms by wyllie and raymer underestimate the observed sonic velocities probably because they do not account for variations in texture carbonate mineralogy and pore geometry petrographic observations show that postburial diagenesis is minor and does not seem to significantly affect porosity therefore the outcrop data set can be regarded as a proxy for the subsurface analog these findings underline the significantly more complex acoustic behavior in mixed carbonate siliciclastic sedimentary rocks than in pure siliciclastics where mineralogic composition explains most of the observed relationships between porosity and sonic velocity

evidence from the lake champlain valley for a later onset of the champlain sea and implications for late glacial meltwater routing to the north atlantic abstract ocean circulation models indicate that freshwater runoff from the north american continent during the last deglaciation may have had an effect on north atlantic ocean circulation and thereby have altered regional climate one such example is a flood from lake agassiz which has been proposed by previous workers to have caused the onset of the younger dryas at around 12 850 calibrated years b p by entering the north atlantic through the gulf of st lawrence we present two radiocarbon ages from terrestrial organic sources in the champlain valley that we associate with the pre champlain sea proglacial lake phases a musk ox bone with an ams age of 11 362 115 14 c years b p 13 438 13 020 calibrated years b p and a wood fragment with an ams age of 10 901 76 14 c years b p 12 995 12 793 calibrated years b p these ages together with a glacial lacustrine varve estimate suggest that the initiation of the champlain sea may not have occurred until after the onset of the younger dryas if the lake agassiz flood event occurred before the opening of the champlain sea then the floodwaters would have been diverted down the champlain and hudson valleys to the north atlantic another possibility is that the agassiz flood may have been contemporaneous with the opening of the gulf of st lawrence it is also possible that there may have been a large enough flood produced by meltwater originating in the champlain valley and st lawrence lowlands at the inception of the champlain sea to have affected ocean circulation without the influence of lake agassiz

acoustic properties in travertines and their relation to porosity and pore types abstract sonic velocities of pleistocene travertines were measured under variable confining pressures combined with petrographical characteristics and petrophysical data i e porosity permeability and density it was determined that travertine porosity pore types and cementation control compressional wave vp and shear wave velocity vs at 40 mpa confining pressures vp ranges between 3695 and 6097 m s and vs between 2037 and 3140 m s velocity variations in travertines are as with all carbonates primarily linked to sample heterogeneity i e differences in fabric texture and porosity they thus not necessarily emanate from changes in mineralogy or composition body wave velocities have a positive correlation with sample density and an inverse correlation with porosity the travertines sampled in extensional settings with normal faulting activity define a specific compressional wave velocity y axis versus porosity x axis equation i e log y 0 0048x 3 7844 that differs from the vp porosity paths defined by marine carbonates acoustic wave velocities are higher for travertines than for marine carbonates travertine precipitates form rigid rock frames often called framestone with large primary pores marine carbonates on the other hand often consist of cemented transported sediments resulting in a rock frame that permits slower wave propagation when compared to the continental limestones acoustic velocity variations are linked to variations in pore types mouldic pores macropores show faster wave propagation than expected from their total porosities microporosity interlaminar and interpeloidal porosity result in slower acoustic velocities framework pores and micro moulds are associated with lowered acoustic velocities while vug porosity is found above on and below the general velocity porosity trend not only the pore type but also pore shapes exert control on body wave velocities cuboid and rod like pore shapes increase the velocity while plate and blade like pore shapes have a negative effect on the velocity the study demonstrates how seismic sections in travertine systems can contain seismic reflections that are not caused by non carbonate intercalations but relate to geobody boundaries in which the seismic expression is function of porosity pore types and shapes this study provides and relates petrophysical data i e porosity permeability and acoustic velocities of travertines and is of importance for the interpretation of seismic reflection data in subsurface continental carbonate reservoirs

testing the mid holocene relative sea level highstand hypothesis in north wales uk accurate holocene relative sea level curves are vital for modelling future sea level changes particularly in regions where relative sea level changes are dominated by isostatically induced vertica

modeling elastic properties in carbonate rocks carbonate limestone and dolomite reservoirs account for approximately 50 of oil and gas production worldwide however seismic responses in carbonate rocks are poorly understood in addition dhi ranking and avo classification systems developed for clastic rocks are unlikely to be applicable to carbonate rocks an accurate and physically sound carbonate rock physics model is needed to address these technical issues

a new velocity model for clay sand mixtu res1 none of the standard porosity velocity models e g the time average equation raymer s equations is satisfactory for interpreting well logging data over a broad depth range clays in the section are the usual source of the difficulty through the bias and scatter that they introduce into the relationship between porosity and p wave transit time because clays are composed of fine sheet like particles they normally form pores with much smaller aspect ratios than those associated with sand grains this difference in pore geometry provides the key to obtaining more consistent resistivity and sonic log interpretations a velocity model for clay sand mixtures has been developed in terms of the kuster and toksoz effective medium and gassmann theories in this model the total pore space is assumed to consist of two parts 1 pores associated with sand grains and 2 pores associated with clays including bound water the essential feature of the model is the assumption that the geometry of pores associated with sand grains is significantly different from that associated with clays because of this porosity in shales affects elastic compliance differently from porosity in sand stones the predictive power of the model is demonstrated by the agreement between its predictions and laboratory measurements and by its ability to predict sonic logs from other logs over large depth intervals where formations vary from unconsolidated to consolidated sandstones and shales

proximal distal facies relationships and sedimentary processes in a storm dominated carbonate ramp kimmeridgian northwest of the iberian ranges spain abstract facies analysis of the upper kimmeridgian rocks in the outcrops located near ricla zaragoza province northeast spain and the integration of the resultant data in a broader context the northern part of the iberian basin has produced two general models showing the facies distribution and the processes that controlled the sedimentation in the kimmeridgian carbonate ramp using these two models the transition from shallow to relatively deep environments of the carbonate ramp is examined in detail model 1 corresponds to the development of a mixed carbonate siliciclastic ramp during a slow rise and stillstand of sea level sequence 1 hst whereas model 2 represents the growth of a pure carbonate ramp during a rapid rise of sea level sequence 2 tst carbonate production was higher in the shallow ramp domains coral reefs and oolitic shoals in model 1 and reefs in model 2 than in deeper domains where there is no indication of significant pelagic or benthic production the activity of unidirectional return flows induced by winter storms and hurricanes played an important role in the redistribution of the sediment across the ramp generating different coarse grained deposits in the inner and mid ramp settings dunes lower scale bedforms and tempestites occur in model 1 and storm lobes bars and tempestites in model 2 moreover a significant bulk of the carbonate mud produced in shallow areas would eventually be resedimented in the outer ramp as suspended load in the density currents stillstand of sea level in model 1 involved a rapid progradation of the inner and proximal mid ramp carbonate and siliciclastic facies the rapid relative sea level rise of model 2 is determined by the dominance of the carbonate facies and by the presence of aggradational geometries in the transitional area between shallow and deep ramp domains the presence of relatively thick sections in the outer ramp settings instead of condensed sections as observed in model 1 during times of sea level rise model 2 can mainly be explained by the increase of the shallow production in the reef dominated areas

velocities of compressional and shear waves in limestones carbonate rocks are important hydrocarbon reservoir rocks with complex textures and petrophysical properties porosity and permeability mainly resulting from various diagenetic processes compaction dissolution precipitation cementation etc these complexities make prediction of reservoir characteristics e g porosity and permeability from their seismic properties very difficult to explore the relationship between the seismic petrophysical and geological properties ultrasonic compressional and shear wave velocity measurements were made under a simulated in situ condition of pressure 50 mpa hydrostatic effective pressure at frequencies of approximately 0 85 mhz and 0 7 mhz respectively using a pulse echo method the measurements were made both in vacuum dry and fully saturated conditions in oolitic limestones of the great oolite formation of southern england some of the rocks were fully saturated with oil the acoustic measurements were supplemented by porosity and permeability measurements petrological and pore geometry studies of resin impregnated polished thin sections x ray diffraction analyses and scanning electron microscope studies to investigate submicroscopic textures and micropores it is shown that the compressional and shear wave velocities vp and vs respectively decrease with increasing porosity and that vp decreases approximately twice as fast as vs the systematic differences in pore structures e g the aspect ratio of the limestones produce large residuals in the velocity versus porosity relationship it is demonstrated that the velocity versus porosity relationship can be improved by removing the pore structure dependent variations from the residuals the introduction of water into the pore space decreases the shear moduli of the rocks by about 2 gpa suggesting that there exists a fluid matrix interaction at grain contacts which reduces the rigidity the predicted biot gassmann velocity values are greater than the measured velocity values due to the rock fluid interaction this is not accounted for in the biot gassmann velocity models and velocity dispersion due to a local flow mechanism the velocities predicted by the raymer and time average relationships overestimated the measured velocities even more than the biot model

laboratory measurements of the acoustic and transport properties of carbonate rocks and their link with the amount of microcrystalline matrix laboratory data and computer tomography ct scan image analysis of carbonate rocks were combined demonstrating a quantitative link between acoustic and transport properties the fraction of microcrystalline calcite micrite in the matrix and the grain to micrite matrix ratio samples from the monte acuto formation gargano italy a transgressive system tract tst whose microstructure ranges from basal pelagic mudstones to coarse calciturbidites were analyzed results indicate that high micrite rocks with low grain to micrite matrix ratios typical of low energy depositional settings are relatively stiffer and more impermeable in contrast lower amounts of micrite due to high energy depositional settings or its removal from intergranular macropores by progressive leaching of the matrix leads to high grain to micrite matrix ratios this process will increase porosity and reduce rock stiffness both of which reduce velocity decreasing micrite content correlates well with increasing macroporosity

field evaluation of the hydromechanical behavior of flat lying fractures during slug tests summary slug tests were conducted at depths of 20 50 m in a fractured gneiss and axial displacements were measured along the borehole with a portable extensometer in order to evaluate the feasibility of combining pressure and displacement measurements to improve the characterization of fractured rock displacements on the order of microns occurred during slug tests when maximum head changes were on the order of meters maximum displacement lagged behind the maximum head and the signals at a given location were repeatable to within reasonable tolerances tests were conducted at 12 packed off depth intervals in a borehole and the signals from each interval were distinctly different from those at other depths parameter estimation techniques were used with a hydromechanical model to interpret the field results and the findings show that there are three transmissive zones in the borehole and the compliance of the fractures generally decreases with depth the inversion also highlights the importance of considering heterogeneities in the vicinity of the well bore when interpreting hydromechanical tests zones of leakage and blockage in the fractures were predicted in the vicinity of the well bore and their presence had a significant effect on the displacement signals

mesozoic extensional tectonics stratigraphy and crustal evolution during the alpine cycle of the eastern iberian basin abstract sequence stratigraphy subsidence analysis and the integration of the basin fill data allow to the identification of four successive evolutionary stages in the basins of the eastern iberian margin during mesozoic extension 1 triassic rift late permian hettangian 2 early and middle jurassic postrift sinemurian oxfordian 3 late jurassic and early cretaceous rift kimmeridgian middle albian and 4 late cretaceous postrift late albian maastrichtian the present day crustal structure of the eastern iberian range and evidence of its evolution are deduced from the analysis of a new gravity map and other geophysical data a regional gravity low along the iberian range is interpreted in terms of crustal thickening beneath the orogen as a result of the collision between the ebro block and the iberian plate during the paleogene the boundary between these blocks coincides with a magnetic lineament that is interpreted as an inherited signature of the thinning that occurred during mesozoic extension a geodynamic scenario for the crustal evolution of the eastern part of the iberian peninsula based on the evaluation of mesozoic extensional tectonics and an analysis of the available geophysical data includes three main successive evolutionary stages 1 1 mesozoic crustal thinning 2 2 paleogene crustal thickening 3 3 neogene crustal thinning based on new geological and geophysical arguments this study offers an alternative and a more complete geodynamic history of the eastern iberian basins related to the evolution of the iberian plate and the central north atlantic

sedimentological petrophysical and seismic characterization of an upper jurassic shoreface dominated shelf margin the boulonnais northern france abstract the integration of high resolution 25 cm vertical spacing and continuous quantitative data on grain size carbonate content porosity density and p wave velocity from outcrop borehole and core over 1000 samples and a real seismic section allows a calibration of seismic sequence stratigraphic principles this approach has been tested in the boulonnais along the english channel coast in northern france on a succession of upper jurassic sharp based shoreface deposits embedded in offshore marine shales statistical analyses of grain size distributions allow a characterization of hydrodynamic conditions and depositional processes affecting low inclination shelf margins and create a framework for identifying locations of preferential and enhanced carbonate cementation which exerts primary control on reservoir and acoustic properties stratigraphic surfaces and systems tracts are quantified for physical properties and results in a quantitative mechanical sequence stratigraphic model the combination of this model with seismic wavelets and a contrast between this synthetic and a real seismic section shows that key bounding sequence stratigraphic surfaces are in fact discontinuous reflectors because stratal relationships of sharp based shoreface deposits are subtle physical contrasts are generally stratabound and the deposits are typically not very thick the geological recordings of sea level falls and potential reservoirs are easily overlooked or go unseen in seismic sequence stratigraphic analyses by defining key diagnostic seismic criteria for sharp based shoreface deposits this study contributes to the understanding of processes controlling sedimentary fills of epicontinental basins

relative sea level change and postglacial isostatic adjustment along the coast of south devon united kingdom previous sea level studies suggest that southwest britain has the fastest subsiding coastline in the united kingdom but tide gauge data gps and gravity measurements and geophysical models show little evidence of anomalous subsidence in this region in this paper we present 15 new sea level index points from four coastal barrier systems in south devon eight are from compaction free basal sediments and others were corrected for autocompaction our data suggest that relative sea level along the south devon coastline has risen by 21 4 m during the past 9000 years sea level rise slowed during the middle and late holocene and a rise of 8 1 m has occurred since ca 7000 cal yr bp anomalous ages for many rejected points are attributed to sediment reworking during barrier transgression the relative sea level history during the early and middle holocene shows a good fit with geophysical model predictions but the geological and modelled data diverge in the later holocene unlike the geophysical models sea level index points cannot differentiate between late holocene relative sea level histories of south devon and southwest cornwall it is suggested that this discrepancy can be resolved by obtaining additional high quality sea level index points covering the past 4000 years copyright 2008 john wiley sons ltd

salt freshwater dynamics in a subterranean estuary over a spring neap tidal cycle this paper presents field measurements and numerical simulations of pore water salinities and groundwater flow in the intertidal zone of an unconfined coastal aquifer over a spring neap tidal cycle the study provides insight into the extent and time scales of mixing between fresh groundwater and recirculating seawater in a tidally influenced subterranean estuary salt freshwater dynamics in subterranean estuaries are currently not well understood despite their potentially important implications for fluxes of chemicals to coastal waters via submarine groundwater discharge the data and simulation results show that changes in the tidal shoreline excursion over the spring neap cycle induce significant variations in the intertidal salinity structure observed higher frequency salinity fluctuations demonstrate further the intensity and complexity of the salt freshwater mixing process in contrast with the salinity variations fresh groundwater was found to discharge around a distinct intertidal beach slope break throughout the spring neap period this suggests that the slope break may affect significantly groundwater flow and salt transport near the shore measurements of ph and dissolved oxygen distributions revealed important biogeochemical zonations in the system these zonations are expected to strongly influence the fate of many reactive chemicals in the nearshore aquifer and their subsequent discharge to coastal waters

time average equation revisited expressions that relate velocity to porosity and to pore fluid compressibility are among the most important deliverables of rock physics such relations are used often as additional controls for inferring porosity from well logs as well as in situ indicators of pore fluid type the oldest and most popular is the wyllie et al 1956 equation p s f where p is the measured traveltime of a p wave s is the traveltime expected in the solid phase material and f is the traveltime expected in the pore fluid it follows from equation 1 that 1vp 1 vps vpf where is porosity vp is the measured p wave velocity and vps and vpf are the p wave velocities in the solid and in the pore fluid phases respectively

groundwater waves in a coastal aquifer a new governing equation including vertical effects and capillarity groundwater waves that is water table fluctuations are a natural phenomenon in coastal aquifers they represent an important part of the interaction between the ocean and aquifer and affect the mass exchange between them this paper presents a new groundwater wave equation because it includes the effects of vertical flows and capillarity the new equation is applicable to both intermediate depth aquifers and high frequency waves compared with the wave equation derived by nielsen et al 1997 the present equation provides a closer representation of groundwater waves in particular it predicts high frequency water table fluctuations as observed in the field a validation of the new equation has been carried out by comparing the analytical solutions to it with predictions from direct simulations using the numerical model sutra the effects of various physical parameters and their relative importance are also discussed

effects of porosity and clay content on wave velocities in sandstones the ultrasonic compressional vp and shear vs velocities and first arrival peak amplitude ap were measured as functions of differential pressure to 50 mpa and to a state of saturation on 75 different sandstone samples with porosities ranging from 2 to 30 percent and volume clay content c ranging from 0 to 50 percent respectively both vp and vs were found to correlate linearly with porosity and clay content in shaly sandstones at confining pressure of 40 mpa and pore pressure of 1 0 mpa the best least squares fits to the velocity data are vp km s 5 59 6 93 2 18c and vs km s 3 52 4 91 1 89c deviations from these equations are less than 3 percent and 5 percent for vp and vs respectively the velocities of clean sandstones are significantly higher than those predicted by the above linear fits about 7 percent for vp and 11 percent for vs which indicates that a very small amount of clay 1 or a few percent of volume fraction significantly reduces the elastic moduli of sandstones for shaly

comparing flux averaged and resident concentration in a fractured bedrock using ground penetrating radar this is the published version copyright 2010 by the american geophysical union all rights reserved

frequency dependent hydraulic properties estimated from oscillatory pumping tests in an unconfined aquifer summary oscillatory pumping tests were conducted at the boise hydrogeophysical research site a periodic pressure signal is generated by pumping and injecting water into the aquifer consecutively and the pressure response is recorded at many points around the source we present and analyze the data from the field test after applying fourier analysis we then match the data with a recently derived analytical solution for homogeneous formations to estimate the equivalent aquifer properties conductivity k specific storage s s and specific yield s y the estimated values are shown to be in agreement with previous estimates conducted at this site we observe variations in the estimated parameters with different oscillation periods of pumping the trend of the parameters with changing period is discussed and compared to predictions by existing theory and laboratory experiments dealing with dynamic effective properties it is shown that the results are qualitatively consistent with recent works on effective properties of formations of spatially variable properties in oscillatory flow to grasp the impact of heterogeneity a simple configuration is proposed helping explain the observed increase in effective conductivity with decreasing period

variations in petrophysical properties along a mixed siliciclastic carbonate ramp upper jurassic ricla ne spain abstract a multi scale petrophysical study was performed on an upper jurassic siliciclastic carbonate ramp system near the village of ricla spain a combination of textural field observations thin section and grain size analysis chemical mineralogical thermo gravimetric analysis and physical porosity gamma ray and velocity measurements properties was used to capture the heterogeneity of this mixed sedimentary system subsequently synthetic seismic sections with varying resolution were created to show the characteristics of the internal ramp structures the translation from the measured petrophysical properties to a synthetic seismic section helps to better understand subsurface seismic although upscaling problems are a recurring issue the homogeneity of the samples and the continuity of the outcrop and facies reduce the number of uncertainties acoustic properties are generally controlled by the amount and type of pore spaces due to the low porosities the ramp geometry is characterized by an overall lateral homogeneity and vertical heterogeneity textural sedimentological and stratigraphic transitions in the outcrop are related to the defined facies each has its own unique mineralogical signature amplitude variations in the synthetic seismic profile are primarily caused by changes in mineral composition thus facies transitions

factors controlling elastic properties in carbonate sediments and rocks carbonate sediments are prone to rapid and pervasive diagenetic alterations that change the mineralogy and pore structure within carbonate rocks in particular cementation and dissolution processes continuously modify the pore structure to create or destroy porosity in extreme cases these modifications can completely change the mineralogy from aragonite calcite to dolomite or reverse the pore distribution whereby original grains are dissolved to produce pores as the original pore space is filled with cement to form the rock figure 1 all these modifications alter the elastic properties of the rock and therefore the sonic velocity the result is a dynamic relationship among diagenesis porosity pore type and sonic velocity the result is a wide range of sonic velocity in carbonates in which compressional wave velocity vp ranges from 1700 to 6600 m s and shear wave velocity vs from 600 to 3500 m s

measuring well hydraulic connectivity in fractured bedrock using periodic slug tests summary periodic hydraulic experiments were conducted in a five spot well cluster completed in a single bedding plane fracture tests were performed by using a winch operated slug submerged solid cylinder to create a periodic head disturbance in one well and observing the phase shift and attenuation of the head response in the remaining wells transmissivity t and storativity s were inverted independently from head response inverted t decreased and s increased with oscillation period estimated s was more variable among well pairs than t suggesting s may be a better estimator of hydraulic connectivity among closely spaced wells these estimates highlighted a zone of poor hydraulic connection that was not identified by a constant rate test conducted in the same wells periodic slug tests appear to be a practical and effective technique for establishing local scale spatial variability in hydraulic parameters

flandrian sea level changes in the fenland i the geographical setting and evidence of relative sea level changes the flandrian sediments of the fenland record the infilling of the wash embayment on the east coast of england uk since at least 6500 bp changes in sea level have been a major control on the rate and pattern of sediment accumulation new data are presented from the area which together with published information allow the reconstruction of palaeoenvironments from 6500 to 2500 bp the major environmental changes involved alternations between freshwater fen and intertidal marine sedimentation each episode was characterised by transitional changes as vegetation and sediment zones shifted over large areas marine brackish sediments are found up to 45 km inland of the present coast radiocarbon dated sea level index points with relevant stratigraphic and micropalaeontological data ranging from 6415 bp at 8 17m od to 2595 bp at 1 45m od are described

acoustic properties of carbonates effects of rock texture and implications for fluid substitution more than 250 plugs from outcrops and three nearby boreholes in an undisturbed reef of miocene tortonian age were quantitatively analyzed for texture mineralogy and acoustic properties we measured the p and s waves of carbonate rocks under dry humidified and brine saturated conditions at 10 mpa effective pressure with an ultrasonic pulse transmission technique 1 mhz the data set was compared with an extensive database of petrophysical measurements of a variety of rock types encountered in carbonate sedimentary sequences two major textural groups were distinguished on the basis of trends in plots of compressional wave velocity versus poisson s ratio a specific ratio of p wave over s wave velocity in granular rocks the framework of depositional grains is the main medium for acoustic wave propagation in crystalline rocks this medium is provided by a framework of interlocking crystals formed during diagenesis rock textures are connected to primary depositionalparameters and a diagenetic ov

middle and late holocene sea level changes in eastern maine reconstructed from foraminiferal saltmarsh stratigraphy and ams 14c dates on basal peat abstract a relative sea level history is reconstructed for machiasport maine spanning the past 6000 calendar years and combining two different methods the first method establishes the long term 10 3 yr trend of sea level rise by dating the base of the holocene saltmarsh peat overlying a pleistocene substrate the second method uses detailed analyses of the foraminiferal stratigraphy of two saltmarsh peat cores to quantify fluctuations superimposed on the long term trend the indicative meaning of the peat the height at which the peat was deposited relative to mean tide level is calculated by a transfer function based on vertical distributions of modern foraminiferal assemblages the chronology is determined from ams 14 c dates on saltmarsh plant fragments embedded in the peat the combination of the two different approaches produces a high resolution replicable sea level record which takes into account the autocompaction of the peat sequence long term mean rates of sea level rise corrected for changes in tidal range are 0 75 mm yr between 6000 and 1500 cal yr b p and 0 43 mm yr during the past 1500 years the foraminiferal stratigraphy reveals several low amplitude fluctuations during a relatively stable period between 1100 and 400 cal yr b p and a sea level rise of 0 5 m during the past 300 years

reconstructing holocene sea level change from coastal freshwater peat a combined empirical and model based approach this paper presents a novel method to reconstruct sea level change in coastal freshwater back barrier marshes freshwater environments have long been considered to be unsuitable for the reconstruction of holocene sea level changes as they provide limiting rather than precise sea level index points we recorded the stratigraphy of a small beach and back barrier coastal phragmites reed marsh at hallsands south devon southwest england using hand drilled cores and ground penetrating radar and collected five new sea level index points from the base of a holocene peat sequence to refine the regional holocene relative sea level curve we demonstrate that the samples despite their freshwater origin yield accurate sea level index points as determined from the quantifiable relationship between tide levels and groundwater by means of water table monitoring and groundwater modelling we show that the primary controls on the water table in the marsh are 1 stratigraphy 2 peat permeability and 3 recharge rates in the back barrier marsh the five index points document relative sea level positions between 7200 and 2400 cal yr bp three points are in good agreement with previously collected regional data from inter tidal deposits and two points usefully fill gaps in the existing reconstruction an amended holocene relative sea level curve for south devon based on 30 data points is presented we conclude that the combined approach of data collection and modelling used in this paper can be applied to similar coastal settings around the world and allows the collection of sea level index points from locations not previously thought suitable for this purpose

identification of systems tracts in low angle carbonate ramps examples from the upper jurassic of the iberian chain spain abstract the upper jurassic of the iberian chain in northeast spain was selected for the study and identification of sequence boundaries and systems tracts in low relief carbonate ramp systems the study area provides a special opportunity for sequence stratigraphic analysis because the outcropping upper jurassic carbonate ramps are relatively undeformed well exposed from proximal to distal areas and have an established ammonite zonation two sequences are recognized sequence a uppermost callovian to uppermost oxfordian in age up to 60 m thick in the proximal areas and between 15 and 5 m thick in the middle and distal areas and sequence b kimmeridgian to lowermost tithonian from 80 to 160 m in thickness across the basin the evolution of the first sequence is related to regional relative sea level changes i e tectono eustatic changes superimposed on the sedimentary basin on the other hand the larger accommodation created during the second sequence is regarded as controlled mainly by steady subsidence sequence boundaries indicative of subaerial exposure show as unconformities with stratigraphic hiatuses in the proximal areas of the basin the lowstand systems tract in sequence a is represented by a decimetre thick reworked level consisting of several ammonite biozones in sequence b this systems tract consists of a thick wedge shaped marly unit in both sequences the transgressive surface overlaying these lowstand deposits is generally planar and marks a sharp boundary between the restricted and open marine fossils however in sequence b in the middle part of the basin the transgressive surface can be absent instead a transitional change to open marine facies exists the transgressive systems tracts show sedimentary condensation at least in the distal areas of the basin with mostly ammonites and benthic fossil wackestones the transgressive unit is generally overlain by a hard ground surface that corresponds to a maximum flooding surface finally in the upper part of both sequences highstand systems tracts are represented by progradational siliciclastic and shallow carbonate complexes in the proximal areas of the basin in sequence a sedimentation is condensed in the distal areas with glauconite marl levels present the descriptions of sedimentary features of the systems tracts of these two sequences developed in a low angle carbonate ramp are suggested to be used as tools for the recognition of systems tracts patterns within sequences in comparable depositional settings

integrated high precision analyses of holocene relative sea level changes lessons from the coast of maine a suite of salt marsh peat samples from four sites along the coast of maine wells phippsburg gouldsboro and machiasport has been analyzed using high precision techniques to determine local relative sea level trends and to evaluate proposed along coast warping a spatially variable set of relative sea level records in maine would have important implications for geophysical models that predict the response of the lithosphere during deglaciation and postglacial isostatic relaxation the amplification of m sub 2 tidal range in the gulf of maine and the bay of fundy during the holocene is modeled and applied to the mean high water data yielding best estimate envelopes of mean tide level change for each location average long term thousands of years mean tide level rise did not exceed approx 2 mm yr at any time during the late holocene at wells phippsburg and machiasport between 4 5 and 3 ka calibrated cal the apparent rate of rise at gouldsboro was higher than at any other site studied this along coast variation in the rate of mean tide level rise may reflect time of deglaciation neotectonics or differential isostatic adjustments a slight acceleration of mean tide level rise has occurred during the past millennium in gouldsboro and machiasport if 12 m downwarping inmore easternmost maine occurred as suggested in other publications it must have happened prior to 5 7 ka cal 84 refs 13 figs 8 tabs less

geological significance of seismic reflections and imaging of the reservoir architecture in the malampaya gas field philippines the integration of petrographic analyses of cores and thin sections petrophysical measurements and well logs demonstrates that variations in acoustic impedance in the malampaya buildup upper eocene to lower miocene offshore northwest palawan are related to vertical changes in porosity and pore type which are dominantly controlled by diagenetic processes the nido limestone was subdivided into 10 50 m 30 150 ft thick units characterized by specific diagenetic patterns and petrophysical properties diagenetic units the alternation between tight and porous diagenetic units is mainly controlled by meteoric diagenesis leaching and pedogenesis and by late burial cementation and leaching well to seismic ties show that the main seismic reflectors within the buildup interior reflect the boundaries between diagenetic units most of the negative amplitude reflectors are related to unconformities whereas positive amplitude reflectors have a more questionable chronostratigraphic value and may represent the bases of cemented lenses that can crosscut time lines comparison with other southeast asian tertiary buildups indicates different origins of seismic reflections related to distinct patterns of diagenetic evolution the identification of such seismodiagenetic units and of their controlling factors is of paramount importance for the architecture and the petrophysical characterization of carbonate reservoirs

relation between stratigraphic architecture and multi scale heterogeneities in carbonate platforms the barremian lower aptian of the monts de vaucluse se france abstract understanding the relationship between multi scale sedimentary heterogeneities and the stratigraphic architectures of carbonate platforms improves the interpretation of paleoenvironmental evolution in time and space such an approach improves the prediction of the spatial distribution of reservoir properties within carbonate stratigraphic units the reservoir scale stratigraphic anatomy and the growth history of a barremian aptian carbonate platform monts de vaucluse se france was based on 1 high resolution measured sections on outcrops 2 detailed microfacies analyses 3 paleoenvironmental interpretations 4 biostratigraphy using rudist bivalves foraminifera calcareous algae and locally echinoderm and ammonites and 5 sequence stratigraphic interpretations with a special focus on the identification of discontinuity surfaces with a significant stratigraphic correlation potential and critical environmental meaning the platform succession consists of subtidal mainly infralittoral with rare inter to supratidal deposits thirty types of elementary facies grouped in 12 facies associations have been defined the vertical and lateral changes in paleoenvironments together with the development of remarkable stratigraphic surfaces such as subaerial exposures marine erosional surfaces and drowning surfaces allow the definition of five stratigraphic sequences ranging from the late barremian to the earliest aptian these depositional sequences can be grouped into two distinct carbonate sedimentary systems characterized by specific sedimentary profiles and skeletal and non skeletal components 1 a carbonate platform with stronger hydrodynamic gradients rimmed by a narrow belt of high energy deposits with corals and rudistid rudstone facies and 2 a carbonate ramp dominated by orbitolinids fine grained facies including an elongated high energy oolitic shoal the two dimension architecture of the depositional sequences dimensioned geometries thickness and facies variations and the morphology of the shelf reflect a strong interaction between tectonic differential subsidence sediment production and global environmental conditions at the km scale the gorges de la nesque stratigraphic motif could represent a nested stratigraphic structure within the large scale model which could be implemented for up scaling petrophysical properties from the well to a full field model the association of coral facies to the rudist dominated system in the provence platform is a very clear proxy of the polarity of the carbonate platform and is critical for subsurface facies property modeling based on well data finally at the global scale the stratigraphic architecture and the step wise drowning events of the provence platform confirm and document the precursor events associated with environmental perturbations that affected the carbonate factory prior the oceanic anoxic event 1a oae1a

four dimensional mapping of tracer channelization in subhorizontal bedrock fractures using surface ground penetrating radar 1 to observe flow channeling in situ surface ground penetrating radar gpr was used to detect a saline tracer moving through a sub horizontal bedrock fracture the tracer is mapped using amplitude variations resulting from the significant difference in electromagnetic properties between the tracer and natural ground water within the fracture results show that hydrogeophysical investigations using gpr can successfully image tracer movement in a variety of flow configurations in three spatial dimensions through time hence 4d observed tracer travel paths demonstrated meter scale spatial variability that may be attributed to heterogeneity in fracture aperture

a new holocene relative sea level curve for western brittany france insights on isostatic dynamics along the atlantic coasts of north western europe abstract this study presents new relative sea level rsl data that were obtained in the finistere region western tip of brittany france and the implications those data have for the understanding of the isostatic dynamics across north western europe and more specifically along the atlantic and channel coasts new stratigraphic sequences were obtained and analyzed to derive 24 new sea level index points in which 6 are basal these new data considerably increase the knowledge we have of the rsl evolution along the coasts of western brittany since the last 8 kyr b p from this new dataset rsl was estimated to rise continuously over the last 8 kyr with a major inflection at ca 6 kyr cal bp our results show large vertical discrepancies between the rsl records of brittany and south western uk with the latter plotting several meters below the new data from this comparison we suggest that the two regions underwent a very different pattern and or amplitude of subsidence during the last 8 kyr which has implications for the spatial and temporal pattern of the peripheral bulge of the european ice sheets we compared our data against predictions from glacio isostatic adjustment models gia models there are large misfits between rsl observations and the predictions of the global ice 5g vm2a peltier 2004 glac1 b tarasov and peltier 2002 tarasov et al 2012 briggs et al 2014 and regional uk models biis bradley et al 2009 bradley et al 2011 kuchar kuchar et al 2012 which can t be resolved through significant changes to the deglaciation history and size of the british irish ice sheet paleo tidal modelling corrections indicate regional changes in the tidal ranges played a negligible role in the data model misfits hence we propose that the misfits are due to some combination of i unaccounted mass loss of far field ice sheets antarctic ice sheet or laurentide ice sheet ii unresolved differences in the deglaciation history and size of the fennoscandian ice sheet or more likely iii significant lateral variations in the earth s structure across the english channel

depositional controls on mixed carbonate siliciclastic cycles and sequences on gently inclined shelf profiles the interplay between carbonate production and siliciclastic input produces mixed systems that typically contain a very high degree of lateral and vertical facies heterogeneity this heterogeneity complicates the sequence stratigraphic analysis of mixed systems outcrop studies facilitate the deciphering of controls and understanding of facies distributions within sedimentary successions the picun leufu anticline in the neuquen basin argentina offers the opportunity to integrate large scale depositional architecture with detailed facies descriptions of the shelf to basin successions of the upper jurassic lower cretaceous quintuco picun leufu vaca muerta system the strata in the system are mixed and range in depositional environments from shallow marine sandstones and limestones to deep basinal shales these environments are arranged in metre scale shallowing upward cycles and cycle sets with increasing carbonate proportions in regressive hemicycles increased input of siliciclastic material from the volcanic arc area occurred during phases of relative sea level rise and was controlled by the intensity of along shelf currents the shelf transport was driven by the available accommodation space on the shelf and therefore was a function of the eustatic sea level fluctuations within the studied section a pure carbonate depositional system developed because siliciclastic input was shut down either due to long lived highstand settings or a sudden climatic change to more arid conditions carbonate siliciclastic mixing in this setting is a function of siliciclastic dilution of the carbonate sedimentation and differs from the classical reciprocal sedimentation model which typically includes shut off of carbonate production during lowstand periods in the regional context the subsurface strata of time equivalent reservoirs in the eastern neuquen embayment display strong similarities of architecture indicating that similar mixing processes occurred along most of the neuquen basin

quantification of pore structure and its effect on sonic velocity and permeability in carbonates carbonate rocks commonly contain a variety of pore types that can vary in size over several orders of magnitude traditional pore type classifications describe these pore structures but are inadequate for correlations to the rock s physical properties we introduce a digital image analysis dia method that produces quantitative pore space parameters which can be linked to physical properties in carbonates in particular sonic velocity and permeability the dia parameters derived from thin sections capture two dimensional pore size domsize roundness aspect ratio ar and pore network complexity poa comparing these dia parameters to porosity permeability and p wave velocity shows that in addition to porosity the combined effect of microporosity the pore network complexity and pore size of the macropores is most influential for the acoustic behavior combining these parameters with porosity improves the coefficient of determination r2 velocity estimates from 0 542 to 0 840 the analysis shows that samples with large simple pores and a small amount of microporosity display higher acoustic velocity at a given porosity than samples with small complicated pores estimates of permeability from porosity alone are very ineffective r2 0 143 but can be improved when pore geometry information poa r2 0 415 and domsize r2 0 383 are incorporated furthermore results from the correlation of dia parameters to acoustic data reveal that 1 intergrain and or intercrystalline and separate vug porosity cannot always be separated using sonic logs 2 p wave velocity is not solely controlled by the percentage of spherical porosity and 3 quantitative pore geometry characteristics can be estimated from acoustic data and used to improve permeability estimates

holocene sea level database for the atlantic coast of the united states we have constructed a database of holocene relative sea level rsl observations for the atlantic coast of the united states the database contains 492 index points which locate the position of rsl in time and space and 344 limiting dates which constrain the minimum or maximum limit of former sea level the majority of the index points in the database are from 6 ka bp to present with only 7 older than 6 ka bp spatially index points are distributed between maine and south carolina but there is an absence of data from georgia and the atlantic coast of florida the database is sub divided into 16 regions based on the distance from the former laurentide ice sheet and are classified depending upon their susceptibility to compaction the index points and limiting data demonstrate that rsl did not exceed present 0 m during the holocene except potentially in regions 1 and 2 eastern maine and southern maine rates of rsl change were highest during the early holocene and have decreased over time due to the diminishing response of the earth s mantle to glacial isostatic adjustment and reduction of ice equivalent meltwater input along the atlantic coast of the united states the linear rate of rsl rise prior to 4 ka bp ranged from 0 5 to 4 5 mm a 1 compared to 0 6 1 8 mm a 1 from 4 ka bp to ad 1900 the database suggests minimal 0 3 mm yr changes in these rates of rsl rise during the late holocene deglaciation of the laurentide ice sheet caused the spatial variability captured by the database the maximum rate of late holocene and ongoing rsl rise occurred in mid atlantic regions new jersey and inner delaware because of collapse of the peripheral forebulge

carbonate ramp depositional systems from a late jurassic epeiric platform iberian basin spain a combined computer modelling and outcrop analysis no counterparts to epeiric sea carbonate ramps are known in present day environments this hinders the interpretation of the factors controlling the growth and evolution of these depositional settings in this study we analyse the facies and geometries of two jurassic examples both from outcrop study and through computer modelling this analysis is constrained by two important features of these oxfordian and kimmeridgian ramps firstly they are very well exposed allowing accurate reconstruction of a 200 km section from proximal to distal ramp environments and secondly a time framework for correlation section reconstruction and modelling is provided by a well defined ammonite biostratigraphy the modelling results in a synthetic stratigraphy which closely matches the reconstructed cross sections and when integrated with the field study constrains and provides additional quantitative data on the following aspects of carbonate ramp systems resedimentation by storms is an important process in maintaining the ramp profile through time down ramp transport distances of between 25 and 40 km are indicated from the distribution of storm beds and shallow water allochems and from model matching known stratigraphic thicknesses and geometries modelling sediment production within the time constraints from the ammonite biozones indicates that shallow water carbonate production was 1 2 orders of magnitude less than that predicted for present day open marine carbonate platforms deeper water production rates were reduced by lesser amounts these proportionally higher outer ramp production rates also help to maintain ramp geometries through time the enigmatic slope crest of ramps is shown to result from a combination of higher shallow water production and erosion rates together with loss of accommodation during highstands and high stillstands in the modelled sea level curves the most parsimonious modelling of the two ramp sequences comes from a relative sea level curve composed of a linear subsidence component superposed by 20 and 100 kyr cycles on a third order cycle the third order cycles and their timing do not correspond to those of the exxon curve

holocene land and sea level changes in great britain analysis of more than 1200 radiocarbon dated samples that constrain relative sea levels in great britain over the past 16 000 yr provides estimates of current land level changes negative of relative sea level change maximum relative land uplift occurs in central and western scotland ca 1 6 mm yr 1 and maximum subsidence is in southwest england ca 1 2 mm yr 1 sediment consolidation arising from autocompaction as the sediment accumulates and from land drainage increases the subsidence in areas with thick sequences of holocene sediments with an average effect equivalent to at least an extra ca 0 2 mm yr 1 land subsidence but more in parts of southeast england 0 5 1 1 mm yr 1 modelled changes in tidal range during the mid to late holocene in eastern england suggest that the calculated rate of land subsidence is overestimated unless such changes are quantified the effect is most significant for large coastal lowlands the fenland and humber ca 0 5 and 0 6 mm yr 1 that were tidal embayments during the mid to late holocene

relative sea level changes glacial isostatic modelling and ice sheet reconstructions from the british isles since the last glacial maximum while contributing 1 m equivalent eustatic sea level rise the british isles ice sheet produced glacio isostatic rebound in northern britain of similar magnitude to eustatic sea level change or global meltwater influx over the last 18 000 years the resulting spatially variable relative sea level changes combine with observations from far field locations to produce a rigorous test for quantitative models of glacial isostatic adjustment local ice sheet history and global meltwater influx after a review of the attributes of relative sea level observations significant for constraining large scale models of the isostatic adjustment process we summarise long records of relative sea level change from the british isles and far field locations we give an overview of different global theoretical models of the isostatic adjustment process before presenting intercomparisons of observed and predicted relative sea levels at sites in the british isles and far field for a range of earth and ice model parameters in order to demonstrate model sensitivity and the resolving power available from using evidence from the british isles for the first time we show a good degree of fit between relative sea level observations and predictions that are based upon global earth and ice model parameters independently derived from analysis of far field data with a terrain corrected model of the british isles ice sheet that includes extensive glaciation of the north sea and western continental shelf that does not assume isostatic equilibrium at the last glacial maximum and keeps to trimline constraints of ice surface elevation we do not attempt to identify a unique solution for the model lithosphere thickness parameter or the local scale detail of the ice model in order to provide a fit for all sites but argue that the next stage should be to incorporate an ice sheet model that is based on quantitative glaciological model simulations we hope that this paper will stimulate this debate and help to integrate research in glacial geomorphology glaciology sea level change earth rheology and quantitative modelling copyright 2006 john wiley sons ltd

the lithostratigraphy and biostratigraphy of a holocene coastal sediment sequence in marazion marsh west cornwall u k with reference to relative sea level movements abstract a holocene sedimentary sequence at marazion marsh mount s bay west cornwall u k is examined with reference to coastal evolution and relative sea level change a sample core analyzed in this paper shows the base of the sedimentary sequence rests on weathered bedrock material basal organic rich deposits are overlain by minerogenic materials dominated by sand a sharp contact separates these two sedimentary units changing coastal conditions are reconstructed using lithostratigraphic biostratigraphic and chronometric data from this sequence the lower organic rich unit accumulated between ca 5420 60 and 4380 55 yrs b p substantial changes in the marsh environment involving vegetation succession from initial herb domination to mesophytic woodland and eventually to fen carr reed marsh development is indicated by pollen records from this unit diatom data show increased salinity within the basal sequence as arboreal pollen values decline and fen carr reed marsh becomes established radiocarbon dates from this and other cores from west cornwall are used to construct a local time altitude plot of relative sea level rsl it is concluded that the sediment sequence at marazion marsh appears to have accumulated in an embayed environment the sequence was both indirectly and directly affected by changes in relative sea level position and the influence of protective transgressive coastal morpho sedimentary structures and associated processes of sedimentation during the mid holocene period

late quaternary sea level change and isostatic and tectonic land movements along the belgian dutch north sea coast geological data and model results early and middle holocene sea level data from belgium plot ca 2 m above data from the western netherlands reflecting differential tectonic and isostatic movements the total uplift rate of belgium relative to the western netherlands decays gradually from 0 66 m kyr 1 at 7500 cal yr bp to less than 0 25 m kyr 1 since 5000 cal yr bp the tectonic component of this relative movement inferred from eemian sea level data is in the order of 0 06 to 0 16 m kyr 1 the isostatic component of the uplift is related to the last phase of the collapse of a peripheral bulge under the netherlands and the dutch and german sectors of the north sea and to hydroisostatic subsidence of the north sea basin caused by water loading as sea level rose comparisons with isostatic rebound models show that they predict well the holocene isostatic movement between belgium and the western netherlands and that the predictions are improved when the tectonic component is removed from the observations preliminary evaluation of sea level data from the dutch sector of the north sea shows that glacio hydroisostatic subsidence relative to belgium was significantly greater than for the western netherlands coastal area and spatially highly variable copyright 2002 john wiley sons ltd

estimation of fracture flow parameters through numerical analysis of hydromechanical pressure pulses cappa et al modelling pressure pulses in rock fractures estimation of fracture flow parameters through numerical analysis of hydromechanical pressure pulses frederic cappa 1 yves guglielmi 2 jonny rutqvist 3 chin fu tsang 3 and alain thoraval 4 geosciences azur university of nice sophia antipolis sophia antipolis france geologie des systemes et des reservoirs carbonates university of provence aix marseille france earth sciences division lawrence berkeley national laboratory berkeley usa ineris ecole national superieure des mines de nancy parc de saurupt nancy france corresponding author fax 33 4 92 94 26 10 e mail address cappa geoazur unice fr f cappa