a generalized biot gassmann model for the acoustic properties of shaley sandstones1 we obtain the wave velocities of clay bearing sandstones as a function of clay content porosity and frequency unlike previous theories based simply on slowness and or moduli averaging or two phase models we use a biot type three phase theory that considers the existence of two solids sand grains and clay particles and a fluid the theory which is consistent with the critical porosity concept uses three free parameters that determine the dependence of the dry rock moduli of the sand and clay matrices as a function of porosity and clay content testing of the model with laboratory data shows good agreement between predictions and measurements in addition to a rock physics model that can be useful for petrophysical interpretation of wave velocities obtained from well logs and surface seismic data the model provides the differential equation for computing synthetic seismograms in inhomogeneous media from the seismic to the ultrasonic frequency bands

physics and seismic modeling for monitoring co2 storage we present a new petro elastical and numerical simulation methodology to compute synthetic seismograms for reservoirs subject to co2 sequestration the petro elastical equations model the seismic properties of reservoir rocks saturated with co2 methane oil and brine the gas properties are obtained from the van der waals equation and we take into account the absorption of gas by oil and brine as a function of the in situ pore pressure and temperature the dry rock bulk and shear moduli can be obtained either by calibration from real data or by using rock physics models based on the hertz mindlin and hashin shtrikman theories mesoscopic attenuation due to fluids effects is quantified by using white s model of patchy saturation and the wet rock velocities are calculated with gassmann equations by using an effective fluid modulus to describe the velocities predicted by white s model the simulations are performed with a poro viscoelastic modeling code based on biot s theory where viscoelasticity is described by generalizing the solid fluid coupling modulus to a relaxation function using the pseudo spectral method which allows general material variability a complete and accurate characterization of the reservoir can be obtained a simulation that considers the utsira sand of the north sea illustrates the methodology

geological storage of carbon dioxide carbon dioxide co2 is the main compound identified as affecting the stability of the earth s climate a significant reduction in the volume of greenhouse gas emissions to the atmosphere is a key mechanism for mitigating climate change geological storage of co2 or the injection and long term stabilization of large volumes of co2 in the subsurface in saline aquifers in existing hydrocarbon reservoirs or in unmineable coal seams is one of the more technologically advanced options available a number of studies have been carried out and are reported here they are aimed at understanding the safety physical and chemical behaviour and long term fate of co2 when stored in geological formations until efficient alternative energy options can be developed geological storage of co2 the subject of this volume provides a mechanism to reduce carbon emissions significantly whilst continuing to meet the global demand for energy

a filter to improve seismic discontinuity data for fault interpretation seismic discontinuity attributes quantify the degree to which neighboring seismic traces vary from each other bahorich and farmer 1995 they detect abrupt lateral changes in seismic data character caused by faults diapirs stratigraphic changes and noise an important application is to highlight fault discontinuities for seismic data interpretation for this purpose other discontinuities are considered noise and should be removed ashbridge et al 2000 pedersen et al 2002 albinhassan and marfurt 2003

late cretaceous campanian maastrichtian marine reptiles from the adaffa formation nw saudi arabia marine reptile remains occur in the upper cretaceous lower campanian to lower maastrichtian adaffa formation of nw saudi arabia this is the first detailed report of late mesozoic marine reptiles from the arabian peninsula the fossils include bothremydid cf taphrosphyini turtles dyrosaurid crocodyliforms elasmosaurid plesiosaurs mosasaurs prognathodon plioplatecarpines and an indeterminate small varanoid the assemblage is compositionally similar to contemporary faunas from elsewhere in the middle east north africa and comprises taxa that are typical of the southern margin of the mediterranean tethys

effective elastic properties of solid clays clay minerals are perhaps the most abundant materials in the earth s upper crust as such their elastic properties are extremely important in seismic exploration seismic reservoir characterization and sonic log interpretation because little exists in the literature on elastic properties of clays we have designed a method of measuring effective elastic properties of solid clays clays without pores in this method clay minerals are mixed with a material with known elastic properties to make composite samples elastic properties of these clay minerals are then inverted from the measured elastic properties of the composite samples using the weighted hashin shtrikman average using this method we have measured 66 samples of 16 types of clays in this paper we present a comprehensive data set of elastic properties of solid clays that commonly occur in or are related to petroleum reservoirs although uncertainties up to 10 exist the data set reported here is by far the most comprehensive set of e

cross polarization geophysical model function for c band radar backscattering from the ocean surface and wind speed retrieval the wind speed sensitivity of cross polarization cross pol radar backscattering cross section vh from the ocean surface increases toward high winds the signal saturation problem of vh if it exists occurs at a much higher wind speed compared to the copolarization copol vv or hh sea returns these properties make vh a better choice over vv or hh for monitoring severe weather combined with high spatial resolution of the synthetic aperture radar sar the development of hurricane wind retrieval using vh is advancing rapidly this paper describes a cross pol c band radar backscattering geophysical model function gmf with incidence angle dependence for the full wind speed range in the available data sets up to 56 m s the gmf is derived from radarsat 2 r2 dual polarization dual pol scansar modes with 300 and 500 km swaths the proposed gmf is compared to other published algorithms the result shows that the simulated vh cross section and the retrieved wind speed with the proposed gmf is in better agreement with measurements with careful treatment of noise the vh retrieved wind speeds may extend to mild or moderate conditions the higher fraction of non bragg contribution in vh can be exploited for analysis of surface wave breaking

measurements of sea clutter at low grazing angle in mediterranean coastal environment results of a coastal measurement campaign called mediterranean rfc and clutter environmental experiment marlene are presented and studied the campaign was held in spring 2014 on a dga site in the mediterranean sea region of toulon france three coastal measurement radar systems millimeter wave experimental multifrequency polarimetric high resolution interferometric system fraunhofer fhr marsig wtd 71 and medycis onera were deployed to simultaneously acquire sea clutter measurements during the campaign the in situ oceanic and meteorological conditions were characterized from the rv planet meteorological ship deployed by wtd 71 and by modeling from wavewatch iii and swan wave models radar measurements were performed at the c x ku ka and w bands the measurement results are presented in terms of reflectivity and mean doppler spectrum according to low grazing angle and azimuth variations reflectivity variations are compared with the empirical git model and close results are obtained at the c and ka bands at the same frequency bands mean doppler spectrum velocity is presented and analyzed according to grazing and azimuth angles physical interpretations of electromagnetic interaction with sea surface are discussed

seismic attenuation due to wave induced flow analytical expressions for three p wave attenuation mechanisms in sedimentary rocks are given a unified theoretical framework two of the models concern wave induced flow due to heterogeneity in the elastic moduli at mesoscopic scales scales greater than grain sizes but smaller than wavelengths in the first model the heterogeneity is due to lithological variations e g mixtures of sands and clays with a single fluid saturating all the pores in the second model a single uniform lithology is saturated in mesoscopic patches by two immiscible fluids e g air and water in the third model the heterogeneity is at microscopic grain scales broken grain contacts and or micro cracks in the grains and the associated fluid response corresponds to squirt flow the model of squirt flow derived here reduces to proper limits as any of the fluid bulk modulus crack porosity and or frequency is reduced to zero it is shown that squirt flow is incapable of explaining the measured level of loss 10 sup 2 q sup 1 10 sup 1 within the seismic band of frequencies 1 to 10 sup 4 hz however either of the two mesoscopic scale models easily produce enough attenuation to explain the field data

time lapse monitoring of fluid induced geophysical property variations within an unstable earthwork using p wave refraction abstracta significant portion of the uk s transportation system relies on a network of geotechnical earthworks cuttings and embankments that were constructed more than 100 years ago whose stability is affected by the change in precipitation patterns experienced over the past few decades the vulnerability of these structures requires a reliable cost and time effective monitoring of their geomechanical condition we have assessed the potential application of p wave refraction for tracking the seasonal variations of seismic properties within an aged clay filled railway embankment located in southwest england seismic data were acquired repeatedly along the crest of the earthwork at regular time intervals for a total period of 16 months p wave first break times were picked from all available recorded traces to obtain a set of hodocrones referenced to the same spatial locations for various dates along the surveyed period of time traveltimes extracted from each acquisition were then compared to trac

time lapse seismic surveys in the north sea and their business impact in a time lapse 3 d seismic tl3d project a monitor seismic survey is compared to a base survey ideally the base survey is a 3 d data set acquired before production from the field started normally the monitor survey is acquired after several years of production the observed differences between the base and the monitor survey can be interpreted in terms of changes in fluid saturation and pressure when embarking on a seismic monitoring project it is important to keep the following questions in mind in this article we will answer these questions and illustrate our solutions with two examples what field information might technically be obtained fluid drainage information from tl3d may be used directly to locate fluid fronts in each major flow unit it may also be used to derive lateral variations in permeability of the reservoir and sealing capacity of faults these variations can cause areas of bypassed oil and blocks that are not being drained in general it will help to understand the observed production from the field it is a very powerful method to map production related changes in reservoir fluid saturation and pressure away from the wells tl3d very often reveals some flow behavior that had not been predicted even by history matched flow models this information can be critical to future reservoir development what impact will it have on reservoir management time lapse seismic may be used to optimize the number and location of infill wells to access untapped reserves or to accelerate production ideally this will minimize infill costs and maximize recovery it may also indicate the need to shut off thief zones to avoid premature water or gas breakthrough it will

marine reptiles from the nanaimo group upper cretaceous of vancouver island a new fauna of fossil marine reptiles is described from the late cretaceous nanaimo group of vancouver island the fossils are from the haslam and pender formations upper santonian near courtenay british columbia and include elasmosaurid plesiosaurs turtles and mosasaurs this is only the second fauna of late cretaceous marine reptiles known from the pacific coast the other being from the moreno formation of california maastrichtian the new nanaimo group fossils are some 15 million years older than those from the moreno formation however like the california fauna there are no polycotylid plesiosaurs and one of the mosasaurs is a new genus this reinforces the provinciality of the pacific faunas and their isolation from contemporaneous faunas in the western interior seaway

measurements of sea spikes in microwave backscatter at moderate incidence previous authors have associated large events or sea spikes in the radar cross section of the sea surface with steep or breaking waves here we present a method based on an intensity threshold and the mean doppler frequency to identify and quantify sea spikes likely to be associated with large scale wave breaking this method is applied to microwave measurements of ku band made with a dual polarized doppler scatterometer at a moderate incidence angle 45 from a fixed platform in the north sea for vv and hh polarization the mean normalized radar cross section 0 the frequency of sea spike occurrence n and the sea spike contribution to the mean normalized radar cross section ss0 are correlated with direct measurements of the friction velocity u in the range 13 u 49 cm s 1 the friction velocity exponents for both n and ss0 indicate an approximately cubic dependence while the residual radar cross section res0 0 ss is approximately proportional to friction velocity for u greater than approximately 20 cm s 1 at high friction velocities u 40 50 cm s 1 these data show that the contribution of large sea spikes to the mean radar cross section for measurements between 25 and 45 relative to the wind is in the range of 5 10 for vv polarization and 10 20 for hh polarization

analysis of radar sea return for breaking wave investigation 1 low grazing angle backscattering data collected by a coherent dual polarized radar installed on a fixed tower in the ocean are analyzed to investigate the properties of sea spikes attributable to wave breaking the distribution of breaking wave speed is narrow banded with an average speed between 2 0 and 2 6 m s in mixed seas with wind speeds between 7 and 14 5 m s the corresponding breaking wavelength is between 2 5 and 4 3 m the length or velocity scale of wave breaking is not proportional to the length or velocity scale of the dominant wave this observation reflects the localized nature of the breaking process and may have significant implications on quantifying various breaking properties such as the energy dissipation or area of turnover by breaking waves the fraction of sea spike coverage generally increases with wind speed but the trend of increase is modified by the intensity and relative direction of background swell parameterizations of sea spike coverage needs to take into consideration both wind and wave factors similarities and differences between sea spikes and whitecaps are discussed in particular while both quantities show a similar power law dependence on wind speed the fraction of sea spike coverage is considerably higher than that of whitecap coverage this result reflects the prevalence of steep features that produce quasi specular facets and short scale waves bounded to intermediate waves during breaking these quasi specular facets and bound waves contribute significantly to enhancing the radar sea return but may not entrain air to produce whitecap signature

mesozoic marine reptile palaeobiogeography in response to drifting plates abstract during the mesozoic various groups of reptiles underwent a spectacular return to an aquatic life colonizing most marine environments they were highly diversified both systematically and ecologically and most were the largest top predators of the marine ecosystems of their time the main groups were ichthyosauria sauropterygia thalattosauria and several lineages of testudinata crocodyliformes rhynchocephalia and squamata here we show that the palaeobiogeographical distribution of these marine reptiles closely followed the break up of the supercontinent pangaea and that they globally used the main marine corridors created by this break up to disperse most mesozoic marine reptile clades exhibit a cosmopolitan or at least pandemic distribution very early in their evolutionary history the acquisition of morphological adaptations to a fully aquatic life combined to special thermophysiological characteristics are probably responsible for these animals to become efficient long distance open marine cruisers generally early triassic taxa were near shore animals mainly linked to the tethys or panthalassa coastlines by the end of the triassic and during the jurassic the break up of pangaea resulted in the formation of large marine corridors connecting the tethys to the north atlantic and pacific realms a trend increasing on during the cretaceous with the expansion of the atlantic ocean and the break up of the southern gondwana allowing open sea marine reptiles to spread out over large distances however if large faunal interchanges were possible at a global scale following a dispersal model some provinces such as the mediterranean tethys were characterised by a peculiar faunal identity illustrating an absence of migration with time despite the apparent lack of barriers so if continental drift enabled global circulations and faunal interchanges via dispersals among mesozoic marine reptiles other parameters such as ecological and biological constraints probably also played a role in the local endemic distribution of some of these marine groups as they do today

sensitivity analysis from single well ert simulations to image co2 migrations along wellbores co2 plume imaging is a required step in co2 geological storage for both performance assessment and risk management purposes this work has been performed in the frame of the co2care project and its aim is to develop tools and methodologies to monitor co2 migration and verify the long term well integrity after site abandonment the timely detection of an anomaly is essential to perform a suitable remediation for this purpose downhole tools are permanently installed but it is important to check the resolution and efficiency of the adopted techniques in particular this study investigates the possibility of using electrical resistivity tomography ert to image co2 migrations around observation boreholes through a sensitivity study

quantitative analysis of time lapse seismic monitoring data at the sleipner co2 storage operation the co2 storage operation at sleipner in the norwegian north sea provides an excellent demonstration of the application of time lapse surface seismic methods to co2 plume monitoring under favorable conditions injection commenced at sleipner in 1996 with co2 separated from natural gas being injected into the utsira sand a major saline aquifer of late cenozoic age co2 injection is via a near horizontal well at a depth of about 1012 m below sea level bsl some 200 m below the reservoir top at a rate approaching 1 million tonnes mt per year with more than 11 mt currently stored

a new palaeocene albulid teleostei elopomorpha from the ouled abdoun phosphatic basin morocco a new albulid fish phosphonatator oxyrhynchus based on a single large neurocranium is described from the deposits of the ouled abdoun phosphatic basin morocco the matrix of the fossil contains an elasmobranch assemblage indicating a danian age with some redeposited maastrichtian elements p oxyrhynchus is characterized notably by its elongated snout and by a reduced patch of teeth on the parasphenoid up to now fossil fishes from the ouled abdoun phosphatic basin were mainly known by isolated remains and the recovery of this specimen should be ranked equal to the recent discovery of important very well preserved new material of vertebrates in the sidi daoui area

stratigraphic evidence for the extinction of the ichthyosaurs the extinction of ichthyosaurs is not well understood both in terns of time and of causation although it is supposed to have happened at some point of the late cretaceous four species of ichthyosaurs attributed to the single cosmopolitan genus platypteygius huene 1922 are currently recognized from the albian and cenomanian but after that time only fragmentary remains have been described a review of these available post cenomanian ichthyosaur remains reveals that all are doubtful either from a stratigraphic or a systematic point of view ichthyosaur extinction may be tentatively correlated with the cenomanian turonian boundary events during this interval biological factors such as a break in the food chain attested by severe extinction in marine invertebrates especially belemnites may have led to the extinction of ichthyosaurs

p wave seismic attenuation by slow wave diffusion effects of inhomogeneous rock properties recent research has established that the dominant p wave attenuation mechanism in reservoir rocks at seismic frequencies is because of wave induced fluid flow mesoscopic loss the p wave induces a fluid pressure difference at mesoscopic scale inhomogeneities larger than the pore size but smaller than the wavelength typically tens of centimeters and generates fluid flow and slow diffusion biot waves continuity of pore pressure is achieved by energy conversion to slow p waves which diffuse away from the interfaces in this context we consider a periodically stratified medium and investigate the amount of attenuation and velocity dispersion caused by different types of heterogeneities in the rock properties namely porosity grain and frame moduli permeability and fluid properties the most effective loss mechanisms result from porosity variations and partial saturation where one of the fluids is very stiff and the other is very compliant such as a highly permeable sandstone at shallow depths saturated with small amounts of gas around 10 saturation and water grain and frame moduli variations are the next cause of attenuation the relaxation peak moves towards low frequencies as the background permeability decreases and the viscosity and thickness of the layers increase the analysis indicates in which cases the seismic band is in the relaxed regime and therefore when the gassmann equation can yield a good approximation to the wave velocity

breaking wave contribution to low grazing angle radar backscatter from the ocean surface 1 the anomaly of radar sea spikes defined here as the non bragg scattering events with backscattering cross section of horizontal polarization exceeding that of the vertical polarization has been associated with steep wave features possibly going through wave breaking process with or without whitecap manifestation this property is exploited for using a dual polarized radar as a remote sensing breaking wave detector field data collected in the ocean covering wind speeds from 7 to 15 m s grazing angles from 1 4 to 5 5 and with different levels of background swell influence are analyzed to quantify the radar cross section and doppler velocity from sea surfaces with and without wave breaking key results of the breaking effects are increasing significantly the doppler velocity of both polarizations about 50 faster enhancing the horizontally polarized backscattering cross section drastically with 10 15 db increase and producing relatively small change in the vertically polarized cross section about 1 2 db increase the presence of swell in the same direction of wind waves reduces both the radar backscatter and the impact of breaking waves on radar return by inference the swell presence decreases the ocean surface roughness and breaking activity these results are consistent with earlier in situ surface wave measurements and our expectation of swell modification of breaking process due to interaction of short waves and the orbital velocity of long swell

baurusuchus salgadoensis a new crocodylomorpha from the bauru basin cretaceous brazil abstract baurusuchus salgadoensis is a new baurusuchid crocodylomorph from bauru basin cretaceous brazil partially preserved through a complete skull the fossil comes from a fine sandstone sequence of adamantina formation general salgado county sao paulo state the sedimentary sequence where it was found located in fazenda buriti is considered turonian santonian in age the described species baurusuchus salgadoensis sp nov is a baurusuchid with an antorbital fenestra double external nares with a bony septum two well fused supraorbitals the supratemporal fenestrae larger than the orbits and a quadrangular shaped laterotemporal fenestra the position of the external nares located on anterior and terminal portion of the rostrum together with the theropod like lateral compression of the snout and teeth are indicators that baurusuchus salgadoensis was a terrestrial crocodyliform this was a carnivorous species and the lateral compression of the rostrum could be interpreted as a mechanism to increase the skull resistance forces during biting the pointed conical teeth some with crenulated borders could be used to perforate and to carve the prey the geological context of baurusuchus salgadoensis indicates that it probably lived in a hot and arid climate

studies of dual polarized low grazing angle radar sea scatter in nearshore regions reports on experiments featuring horizontally hh and vertically vv polarized x band marine radar sea scatter imagery in the coastal environments of bermuda and la jolla under light to moderate winds and the absence of long gravity waves these conditions allowed the study of fundamental scattering mechanisms from small scale roughness and short waves of a few meters wavelength or less shorter than the radar pulse while a large fraction of radar data collected revealed the presence of slick bands the authors analyze the radar echo of ambient background outside of the slicks sea scatter data were digitally recorded for 360 spl deg azimuthal coverage for grazing angles between 1 3 5 spl deg and were converted to normalized radar cross section nrcs or spl sigma spl deg images the hh and vv polarizations show quite different spatial texture with hh exhibiting a discrete character and vv being more nearly spatially homogeneous grazing angle dependencies are different for hh and vv upwind downwind differences of mean nrcs show ratios of just 4 6 db for vv but are equal or greater than the 16 db noise imposed limit for hh for the low wind conditions hh nrcs grazing angle characteristics are shown to correlate with biological activity indicators of the coastal waters with a fourth power dependence in relatively unproductive waters to a nearly quadratic in productive waters arguments are presented that suggest different scattering mechanisms for the two polarizations evenly distributed bragg scatter patches for vv and scatter from small asymmetric bore features for hh a multipath illumination model for small bore features is outlined and scale sizes for the small scale breakers inferred from the experimental results presented are between 2 and 4 cm in height with crest widths between 24 and 48 cm

large predatory marine reptiles from the albian cenomanian of annopol poland during the early late cretaceous transition marine ecosystems in eurasia hosted a diverse set of large predatory reptiles that occupied various niches however most of our current knowledge of these animals is restricted to a small number of bonebed like deposits little is known of the geographical and temporal extent of such associations the middle albian middle cenomanian phosphorite bearing succession exposed at annopol poland produces numerous ichthyosaurian and plesiosaurian fossils these are mostly isolated skeletal elements e g teeth vertebrae but disarticulated partial skeletons and an articulated subvertically embedded ichthyosaur skull are also available the following taxa are identified platypterygius sp cf ophthalmosaurinae ichthyosauria indet polyptychodon interruptus pliosauridae indet elasmosauridae indet and plesiosauria indet the large sized ichthyosaur platypterygius and the pliosaurid polyptychodon interruptus predominate within the upper albian middle cenomanian deposits the annopol record combined with data from england france and western russia suggests that platypterygius and polyptychodon interruptus formed a long term stable ecological sympatry in marine ecosystems of the european archipelago at least during the albian middle cenomanian in addition the marine reptile assemblage from annopol is distinct from other eurasian ecosystems in containing also elasmosaurids in its albian portion

seismic modeling to monitor co2 geological storage the atzbach schwanenstadt gas field 1 we develop a petro elastical numerical methodology to compute realistic synthetic seismograms and analyze the sensitivity of the seismic response when injecting carbon dioxide co2 in a depleted gas reservoir the petro elastical model describes the seismic properties of the reservoir rock saturated with co2 methane and brine and allows us to estimate the distribution and saturation of co2 during the injection process the gas properties as a function of the in situ pressure and temperature conditions are computed with the peng robinson equation of state taking into account the absorption of gas by brine wave attenuation and velocity dispersion are based on the mesoscopic loss mechanism which is simulated by an upscaling procedure to obtain an equivalent viscoelastic medium corresponding to partial saturation at the mesoscopic scale having the equivalent complex and frequency dependent bulk dilatational modulus we include shear attenuation and perform numerical simulations of wave propagation at the macroscale by solving the viscoelastic differential equations using the memory variable approach the pseudo spectral modeling method allows general material variability and provides a complete and accurate characterization of the reservoir the methodology is used to assess the sensitivity of the seismic method for monitoring the co2 geological storage at the atzbach schwanestadt depleted gas field in austria the objective of monitoring is the detection of the co2 plume in the reservoir and possible leakages of co2 the leakages are located at different depths where the co2 is present as gaseous liquid and supercritical phases even though the differences can be very subtle this work shows that seismic monitoring of co2 from the surface is possible while the identification of shallow leakages is feasible the detection of the plume and deep leakages located in the caprock just above the injection formation is more difficult but possible by using repeatability metrics such as the normalized rms nrms images considering real data conditions affected by random noise a reference detection threshold for deep leakages and the co2 plume in the reservoir corresponds to a signal to noise ratio of about 10 db

new plesiosaur specimens from the maastrichtian phosphates of morocco and their implications for the ecology of the latest cretaceous marine apex predators abstract article history received 25 august 2012received in revised form 20 november 2012accepted 22 november 2012available online 20 december 2012handling editor p erikssonkeywords cretaceousmoroccotop predatorsmarine reptilesplesiosauriapalaeoecology severalcladesofmarinetetrapods includingtheapexpredatorsmosasaursandplesiosaurs disappearedduringthe mass extinction at the end of the cretaceous about 65 my ago the extreme fossil richness of themaastrichtian phosphates of morocco provides insights into the systematic diversity of the latest mosasaurswhere about ten species are known however data of the coeval plesiosaurs are comparatively scarce up tonow onlyonespecies theelasmosauridzarafasaura oceanis isknown herewedescribenewelasmosaurid ple siosaur post cranial material from the maastrichtian of the oulad abdoun basin morocco that provides newdataaboutthetaxonomicalandmorphologicaldiversityofplesiosaursinthisarea mostofthenewmaterialcon sists ofvertebrae thatlikely belongto a unique elasmosauridtaxon and differfrom all other elasmosaurids doc umented so far as zarafasaura is known only from cranial material it cannot be determined whether the newmaterial may be assigned to this taxon the new material shows that the latest cretaceous plesiosaurs in thislow latitude area about 20 n were rather gracile most likely piscivorous taxa that occupied ecological nichessimilartothoseofrathersmallmosasaurs e g halisaurusand platecarpus ptychodon butdistinctfromthoseofmostcoevallargemosasaurtaxa theseplesiosaurfossilsarealsoremarkableinthattheyconsistofbothjuvenileand adult specimens suggesting limited segregation between individuals of different ontogenetic stages a fea ture that might be attributed to upwelling related high nutrient input and food availability in this area duringthe maastrichtian moreover the possible occurrence with older specimens of a neonate specimen oneamongtheveryfewknownworldwide suggestsapossiblesocialstructureorganization thenewdatacontrib ute to increase our understanding of late cretaceous plesiosaur biodiversity and provide new insights into theecology of latest cretaceous marine apex predators 2012 international association for gondwana research published by elsevier b v all rights reserved

interaction of permo triassic and jurassic extensional fault blocks during the development of the northern north sea the main structural elements resulting from late permian early triassic extension have been resolved across the total width of the northern north sea the northern segment of the basin north of 61 n bounded to the west by the hutton fault and to the east by the norwegian mainland was occupied by four westerly tilted half grabens 25 35 km in width prior to jurassic extension the central segment of the basin 60 20 61 n exhibits a full graben beneath the jurassic horda platform flanked by half grabens tilted towards the basin margins the change in permo triassic fault block configuration defining structural domains is largely constrained by a basement discontinuity which runs diagonally ne sw across the basin maximum jurassic extension is represented by several centres of subsidence aligned nne ssw across a n s oriented and broader permo triassic basin jurassic extension was concentrated within the viking graben proper south of 60 n which in this area is represented by single westerly tilted en echelon half graben segments 20 25 km wide the area affected by jurassic extension becomes progressively wider to the north again governed by the basement discontinuity eventually encompassing the total width of the basin c 200 km north of 61 n the central segment of the northern north sea displays the greatest contrast in permo triassic and jurassic structural styles and basin geometry jurassic stretching and faulting was negligible to the east horda platform precisely the area which had been the site of maximum permo triassic stretching and fault activity it has generally been assumed that jurassic fault configuration along the eastern margin of the central segment of the viking graben to a large extent reflects the reactivation of major permo triassic faults this study demonstrates the interference of permo triassic and jurassic basin geometries in this area due to major faults of the two generations dipping in opposite directions as a consequence the e tilted oseberg fault block of jurassic origin and c 20km in width is underlain by a wider c 35 km and w tilted permo triassic fault block

nano particles as the primary cause for long term sunlight suppression at high southern latitudes following the chicxulub impact evidence from ejecta deposits in belize and mexico life on earth was sharply disrupted 66 ma ago as an asteroid hit the sea floor in what is today yucatan peninsula mexico approximately 600 km 3 of sedimentary rock were vapourized ejected into the atmosphere and subsequently deposited globally as an ejecta apron and fallout layer proximal ejecta deposits occur in belize and southern mexico where the so called albion island spheroid bed is superimposed on the target rock the barton creek formation we analysed the spheroid bed via mossbauer spectroscopy petrology xrd and palynology at several sites similar to 350 500 km distance from the crater centre our results show that the relative concentrations of fe in nano phase goethite alpha feooh are very high in the spheroid bed samples from albion island belize and from ramonal south mexico but are low to absent in the spheroid bed at ramonal north and in the cretaceous target rock moreover our study shows that goethite and haematite are the dominant fe oxide nano phases and the xrd results show that the target rock consists of both calcite and dolomite we suggest that the heterogeneous composition of the spheroid bed between the various sites reflects the different types of target rocks that were dispersed within the rapidly expanding vapour plume and the complex sorting processes involved in the formation of the ejecta blanket the distribution of the vapourized target rock strongly influenced life on earth at the close of the mesozoic however the comparatively thin k pg boundary clay in high latitude gondwanan successions combined with evidence of catastrophic changes to the biota in this region implies that the long term sunlight suppression in the southern hemisphere was mainly governed by the large quantities of hydrous aerosols nucleated around sulphuric acid droplets or nano sized particles such as the nano phase fe oxides c 2014 the authors published by elsevier b v on behalf of international association for gondwana research less

zarafasaura oceanis a new elasmosaurid reptilia sauropterygia from the maastrichtian phosphates of morocco and the palaeobiogeography of latest cretaceous plesiosaurs abstract though the maastrichtian phosphates of morocco have yielded very rich marine vertebrate assemblages plesiosaurs remain very scarce in these strata the only hitherto recognized taxon was plesiosaurus mauritanicus arambourg 1952 regarded here as a nomem dubium here we describe a new genus and species of elasmosaurid plesiosaur zarafasaura oceanis which represents the first valid elasmosaurid plesiosaur described from the latest cretaceous of africa and the second one from this continent a phylogenetic analysis of plesiosauroids indicates that zarafasaura oceanis has close affinities with elasmosaurids from the late cretaceous of north america and japan among its distinctive suite of characters the general shape and organisation of its squamosal and palate are unique among elasmosaurids this new taxon completes our understanding of late cretaceous plesiosaur palaeobiodiversity and palaeobiogeography and shows that maastrichtian plesiosaurs were characterized by a quite high degree of endemism they were also highly diversified and distributed worldwide which supports the hypothesis of a catastrophic extinction of plesiosaurs at the k t boundary

numerical simulation of wave induced fluid flow seismic attenuation based on the cole cole model the acoustic behavior of porous media can be simulated more realistically using a stress strain relation based on the cole cole model in particular seismic velocity dispersion and attenuation in porous rocks is well described by mesoscopic loss models using the zener model to simulate wave propagation is a rough approximation while the cole cole model provides an optimal description of the physics here a time domain algorithm is proposed based on the grunwald letnikov numerical approximation of the fractional derivative involved in the time domain representation of the cole cole model while the spatial derivatives are computed with the fourier pseudospectral method the numerical solution is successfully tested against an analytical solution the methodology is applied to a model of saline aquifer where carbon dioxide co2 is injected to follow the migration of the gas and detect possible leakages seismic monitoring surveys should be carried out periodically to this aim the sensitivity of the seismic method must be carefully assessed for the specific case the simulated test considers a possible leakage in the overburden above the caprock where the sandstone is partially saturated with gas and brine the numerical examples illustrate the implementation of the theory

a feasibility study of co2 geologic sequestration integrating reservoir simulation rock physics theory and seismic modeling abstractco2 capture and sequestration is a promising approach to reduce carbon emission and mitigate the greenhouse effect we have developed a methodology combining reservoir simulation rock physics theory and seismic modeling to simulate the co2 sequestration and monitoring process based on an idealized geologic model of the sleipner field first we simulated a constant rate co2 injection into the idealized geologic model to study the basics of the two phase flow involved in co2 sequestration the main features of the co2 plume evolution and pressure build up are captured in the simulation results in any co2 sequestration project an important part is monitoring co2 distribution using seismic methods the seismic response of the injected co2 is controlled by its effect on elastic properties of the reservoir rock we built a rock physics model to assess the effect of co2 on wave properties for unconsolidated sand a sensitivity study found that co2 saturation and effective pressure can strongly aff

seismic velocity and q anisotropy in fractured poroelastic media a fluid saturated poroelastic isotropic medium with aligned fractures behaves as a transversely isotropic and viscoelastic tiv medium when the predominant wavelength is much larger than the average distance between fractures a planar fracture embedded in a fluid saturated poroelastic background medium can be modeled as a extremely thin and compliant porous layer p waves traveling in this type of medium induce fluid pressure gradients at fractures and mesoscopic scale heterogeneities generating fluid flow and slow diffusion biot waves causing attenuation and dispersion of the fast modes mesoscopic loss a poroelastic medium with embedded aligned fractures exhibits significant attenuation and dispersion effects due to this mechanism which can properly be represented at the macroscale with an equivalent tiv medium in this work we apply a set of compressibility and shear harmonic finite element fe experiments on fractured highly heterogeneous poroelastic samples to determine the five complex and frequency dependent stiffnesses characterizing the equivalent medium the experiments consider brine or patchy brine co 2 saturated samples and a brine saturated sample with a heterogeneous fractal skeleton with fractures we show that fractures induce strong seismic velocity and q anisotropy both for qp and qsv waves enhanced either by patchy saturation or frame heterogeneity