high thermal maturity in the lower saxony basin intrusion or deep burial abstract the lower saxony basin lsb is situated at the southern rim of the northern permian basin the most important hydrocarbon bearing province in europe in its southern part areas of high thermal maturation up to 6 rr occur which were previously explained as being caused by magmatic intrusions of turonian to santonian age that affected carboniferous to lower cretaceous rocks in this area 2d numerical basin modelling was carried out in order to reconstruct the temperature histories along two parallel n s trending seismic sections along these sections new data about maturity distribution and temperature history were obtained by vitrinite reflectance measurements and apatite fission track analysis for the areas with highest maturity values low coalification gradients were established which agree well with earlier published data on wells further towards the west this new information does not support previous hypotheses on high heat flows from magmatic intrusions even if lateral heat transport is taken into account instead comparisons with a recently published map of the subsurface structure of the lsb indicate that maturity distribution may be closely related to major tectonic structures deep burial of individual structures of the lsb which are bordered by deep e w to ese wnw trending faults is further suggested by a rapidly increasing thicknesses of preserved cretaceous strata towards the south and b structural restoration of one of the seismic sections to achieve a fit between measured and calculated palaeo temperature and vitrinite reflectance data deep burial of carboniferous source rocks during cretaceous time has to be assumed due to an inversion phase in the early and middle upper cretaceous major amounts of sediment were removed and further uplift occurred in tertiary times in contrast the northern part of the lsb experienced maximum burial and temperatures during tertiary times

a comparison of burial maturity and temperature histories of selected wells from sedimentary basins in the netherlands sedimentary basins in the netherlands contain significant amounts of hydrocarbon resources which developed in response to temperature and pressure history during mesozoic and cenozoic times quantification and modelling of burial maturity and temperature histories are the major goals of this study allowing for a better understanding of the general geological evolution of the different basins as well as petroleum generation all major basins in the netherlands encountered at least one time of inversion and therefore moderate to high amounts of erosion in order to determine the amount of inversion the basins have experienced a 1d study was performed on 20 wells within three basins west netherlands central netherlands and lower saxony basins new vitrinite reflectance values were obtained and existing data re evaluated to gain a good data base the burial histories of six wells two for each studied basin are presented here to demonstrate the differences in basin evolution that led to their present shape and petroleum potential the permo triassic subsidence phase can be recognized in all three basins but with varying intensity in the jurassic the basins experienced different relative movements that culminated in the cretaceous when the influence of the inversion caused erosion of up to 2 500 m most wells show deepest burial at present day whereas the timing of maximum temperature differs significantly springer verlag 2007

the cenozoic evolution of the roer valley rift system integrated at a european scale the roer valley rift system rvrs is located between the west european rift and the north sea rift system during the cenozoic the rvrs was characterized by several periods of subsidence and inversion which are linked to the evolution of the adjacent rift systems combination of subsidence analysis and results from the analysis of thickness distributions and fault systems allows the determination of the cenozoic evolution and quantification of the subsidence during the early paleocene the rvrs was inverted laramide phase the backstripping method shows that the rvrs was subsequently mainly affected by two periods of subsidence during the late paleocene and the oligocene quaternary time intervals separated by an inversion phase during the late eocene during the oligocene and miocene periods the thickness of the sediments and the distribution of the active faults reveal a radical rotation of the direction of extension by about 70 80j counter clockwise integration of these results at a european scale indicates that the late paleocene subsidence was related to the evolution of the north sea basins whereas the oligocene quaternary subsidence is connected to the west european rift evolution the distribution of the inverted provinces also shows that the early paleocene inversion laramide phase has affected the whole european crust whereas the late eocene inversion was restricted to the southern north sea basins and the channel area finally comparison of these deformations in the european crust with the evolution of the alpine chain suggests that the formation of the alps has controlled the evolution of the european crust since the beginning of the cenozoic

a numerical study of circulation in a coastal reef lagoon system 1 a coupled wave circulation numerical model was used to simulate the distribution of wave energy as well as the circulation induced by wave breaking wind and tidal forcing within a coral reef system in kaneohe bay oahu hawaii modeled wave current and wave setup fields were compared with field measurements collected on the forereef reef flat and reef channels and in the lagoon over a 4 week period the predicted wave height transformation across the reef lagoon system was in good agreement with field observations using single parameter spatially uniform values to describe both wave breaking and frictional dissipation the spatial distribution of the resulting wave setup field drove a persistent wave driven flow across the reef flat that returned to the ocean through two deeper channels in the reef both the magnitude and direction of these currents were well described using a spatially uniform hydraulic roughness length scale notably the model lends support to field observations that setup within the coastally bounded lagoon was a substantial fraction of the maximum setup on the reef 60 80 which generated relatively weak cross reef wave driven flows 10 20 cm s 1 compared with reefs having mostly unbounded lagoons e g many atolls and barrier reefs numerical experiments conducted using lagrangian particle tracking revealed that residence times within kaneohe bay are extremely heterogeneous typically ranging from 1 month within its sheltered southern lagoon

a framework for understanding drag parameterizations for coral reefs 1 in a hydrodynamic sense a coral reef is a complex array of obstacles that exerts a net drag force on water moving over the reef this drag is typically parameterized in ocean circulation models using drag coefficients cd or roughness length scales z0 however published cd for coral reefs span two orders of magnitude posing a challenge to predictive modeling here we examine the reasons for the large range in reported cd and assess the limitations of using cd and z0 to parameterize drag on reefs using a formal framework based on the 3 d spatially averaged momentum equations we show that cd and z0 are functions of canopy geometry and velocity profile shape using an idealized two layer model we illustrate that cd can vary by more than an order of magnitude for the same geometry and flow depending on the reference velocity selected and that differences in definition account for much of the range in reported cd values roughness length scales z0 are typically used in 3 d circulation models to adjust cd for reference height but this relies on spatially averaged near bottom velocity profiles being logarithmic measurements from a shallow backreef indicate that z0 determined from fits to point measurements of velocity profiles can be very different from z0 required to parameterize spatially averaged drag more sophisticated parameterizations for drag and shear stresses are required to simulate 3 d velocity fields over shallow reefs in the meantime we urge caution when using published cd and z0 values for coral reefs

evolution of the lower saxony basin abstract the lower saxony basin is a 300 km long and 65 km wide late jurassic and early cretaceous trough which parallels the northern margin of the rhenish massif this basin became inverted during the senonian and paleocene the lower saxony basin is the most important oil province of germany past production amounts to 200 10 6 t of oil 1 5 10 9 bbl the lower saxony basin is superimposed on the late carboniferous variscan foredeep basin and the frontal structures of the variscan fold belt during the permian to middle jurassic the area formed part of the northwest european basin differential subsidence of the lower saxony basin was initiated during the late jurassic and persisted till albian time this involved reactivation of permo carboniferous fracture systems by divergent wrenching a major aptian deep seated laccolith is evident in the western part of the lower saxony basin during the senonian and paleocene sinistral convergent wrenching induced uplift of the basin floor and folding of its sedimentary fill the margins of the inverted lower saxony basin are thrust over the adjacent stable platform areas the differential subsidence of the lower saxony basin can be related to a period of major crustal extension in the north sea rift basin inversion coincides with important orogenic events in the alpine system and is thought to have been induced by intra plate compressional stresses

the combined influence of hydrodynamic forcing and calcification on the spatial distribution of alkalinity in a coral reef system 1 we investigated the influence of hydrodynamic forcing waves tides alongshore currents and winds and net calcification by coral reef organisms on the spatial distribution of total alkalinity ta in a fringing reef system through a combination of field measurements and numerical modeling a field experiment was conducted over 10 days in coral bay ningaloo reef western australia during which we measured wave heights currents and tides as well as the spatial distribution of ta across the fore reef reef crest and lagoon we used observed changes in ta on the adjacent reef flat along with synoptic measurements of cross reef transport to estimate in situ rates of net calcification gcv using a control volume approach based on the gcv estimated we simulated light driven diurnal variations in benthic net calcification within a three dimensional ocean circulation model roms regional ocean modeling system by coupling roms with a spectral wave model simulating waves nearshore we were able to simulate currents within coral bay reef lagoon system that were in good agreement with the field observations and demonstrate that circulation with the system was wave dominated both the field measurements and numerical model output confirmed that both residence time r and ta varied primarily with offshore wave heights and location within the bay however variations in ta were also affected by the nonlinear interaction between rates of net calcification that varied as a function of diurnally changing light and water residence time that varied as a function of offshore wave heights

measurements of momentum and heat transfer across the air sea interface abstract this study makes direct measurements of turbulent fluxes in the mixed layer in order to close heat and momentum budgets across the air sea interface and to assess the ability of rigid boundary turbulence models to predict mean vertical gradients beneath the ocean s wavy surface observations were made at 20 hz at nominal depths of 2 2 and 1 7 m in 16 m of water a new method is developed to estimate the fluxes and the length scales of dominant flux carrying eddies from cospectra at frequencies below the wave band the results are compared to independent estimates of those quantities with good agreement between the two sets of estimates the observed temperature gradients were smaller than predicted by standard rigid boundary closure models consistent with the suggestion that wave breaking and langmuir circulation increase turbulent diffusivity in the upper ocean similarly the monin obukhov stability function h was smaller in the authors measurements than the stability functions used in rig

geothermal history of the carboniferous in south limburg the netherlands the geothermal history of upper carboniferous rocks in the former mining district of south limburg the netherlands is complex maturity modelling as calibrated by vitrinite reflectance measurements and volatile matter content shows that the present day coalification patterns of the carboniferous were established in late westphalian to early permian times variations in the degree of coalification were mapped using as a reference level the upper westphalian a coal seam gb 23 modelled burial and thermal histories for the area indicate that regional variations in overburden heatflow and in timing of thermal events in front of the variscan orogen caused the spatial variation in coalification in the southern part of the area differences in overburden combined with a generally high heatflow determined the coalification patterns in the northeastern part of south limburg an additional thermal event related to a permian intrusion overprinted the earlier coalification pattern the coalification data are consistent with basement heatflow values during the carboniferous in the order of 46 to 71 mw m2 and erosion following the variscan orogeny of some 2900 m of sediments around sittard and as much as 5400 m in the southeasternmost part of south limburg

numerical modelling of burial and temperature history as an approach for an alternative interpretation of the bramsche anomaly lower saxony basin the lower saxony basin germany is one of the several sedimentary basins within the central european basin system in its southwestern part anomalously high maturity of organic matter has been observed to reach 4 5 vrr in upper jurassic and lower cretaceous sedimentary rocks in an area which coincides with a magnetic and a positive gravimetric anomaly this anomaly was often interpreted as the consequence of a deep seated igneous intrusion the so called bramsche massif however results obtained from calibrated numerical modelling are not in accordance with this scenario instead a burial by approximately 4 km of now eroded cretaceous rocks was revealed to be the probable cause for the anomaly data and modelling results from six boreholes and two pseudo wells support this view

hydrodynamic forces on larvae affect their settlement on coral reefs in turbulent wave driven flow this study investigates a key aspect of how ambient flow affects the recruitment of water dispersed marine larvae onto benthic substrata the sweeping away of larvae that have landed on surfaces through a combination of field and laboratory measurements we studied how waves interact with a complex substratum to affect hydrodynamic forces encountered by microscopic larvae sitting at different positions on the bottom terrain we used larvae of the nudibranch phestilla sibogae settling onto coral reefs as the system to address this question laser doppler anemometry was utilized within a laboratory flume to measure water velocities encountered 200 m mf rom coral surfaces by microscopic larvae sitting at different locations within a reef of the branching coral porites compressa comparing wave driven flow based on conditions measured over p compressa reefs in hawaii with unidirectional flow of the same mean velocity we found that peak shear stresses along coral surfaces were 15 times greater and hydrodynamic forces on larvae were 10 times higher in wave conditions peak forces on larvae sitting on the reef top were 3 10 times greater than on larvae 5 10 cm below the reef top intermittent bursts of high velocity which occurred more often at the reef top than within it determined the settlement probability for larvae in different reef microhabitats the faster and more strongly a larva sticks to a surface the higher the probability of successful settlement using values for p sibogae adhesive strength we predict they can settle only on sheltered surfaces within reefs

late cretaceous and cenozoic intra plate compressional deformations in the alpine foreland a geodynamic model abstract the mesozoic grabens and wrench induced troughs of western and central europe developed in response to triassic early cretaceous intra plate tensional stresses which affected the arctic north atlantic and the tethys borderlands during the rifting phase preceding the opening of the respective oceans this resulted in the fragmentation of the continental crust of the alpine foreland during the late cretaceous and tertiary alpine orogeny collision related compressive stresses exerted on the foreland induced the reactivation of these fracture systems causing the inversion of mesozoic grabens and the uplifting of major basement blocks at distances up to 1300 km to the north of the present alpine deformation front the structural style of these inverted basins and basement uplifts is indicative of compressional and transpressional deformations the total amount of crustal shortening associated with these deformations is unlikely to exceed a few tens of kilometres these displacements require a coupling between the foreland and the orogen at the alpine a subduction zones and within the foreland a decoupling at intra crustal levels between the crust and mantle and or at deeper lithospheric levels the example of the alpine foreland indicates that compressive stresses inducing major deformations can be transmitted from a collisional plate boundary through continental lithosphere over distances of up to 1300 km circumstantial evidence suggests that collision related compressive stresses not large enough to give rise to significant deformations can be transmitted through continental lithosphere over even greater distances

boundary layer turbulence and flow structure over a fringing coral reef measurements of velocity and rates of turbulence were made across a fringing coral reef in the gulf of aqaba red sea to determine the effect that the rough topography has on boundary layer mixing and flow dynamics observations were made at two fore reef sites and a nearby sandy slope the friction velocity u and drag coefficient cd were determined directly from turbulent reynolds stresses measured using acoustic doppler velocimeters values of cd for the coral substrates ranged from 0 009 to 0 015 three to five times greater than over the sandy bottom site the turbulence dissipation rate e was determined by fitting spectra of vertical velocity to the theoretical 5 3 law expected for the inertial subrange of turbulence there was a local balance between production and dissipation of turbulent kinetic energy signifying that we could estimate u from either the mean velocity profile turbulence or dissipation rate of turbulent kinetic energy estimates from all three measures agreed well with mean u uo ranging from 0 10 6 0 03 to 0 12 6 0 03 indicating that existing turbulent boundary layer flow theory can be applied to flows over the rough topography of coral reefs the bottom topography by enhancing both reef scale and local drag and mixing levels allows reef biota to more effectively exchange dissolved and particulate matter with oceanic waters

wave generated flow on coral reefs an analysis for two dimensional horizontal reef tops with steep faces waves breaking on the seaward rim of a coral reef generate a flow of water from the exposed side of the reef to the sheltered side and or to either channels through the reef rim or lower sections of the latter this wave generated flow is driven by the water surface gradient resulting from the wave set up created by the breaking waves this paper reviews previous approaches to modelling wave generated flows across coral reefs and discusses the influence of reef morphology and roughness upon these flows laboratory measurements upon a two dimensional horizontal reef platform with a steep reef face provide the basis for extending a previous theoretical analysis for wave set up on a reef in the absence of a flow gourlay m r 1996b wave set up on coral reefs 2 set up on reefs with various profiles coastal engineering 28 1755 to include the interaction between a unidirectional flow and the wave set up the laboratory model results are then used to demonstrate that there are two basic reef top flow regimes reef top control and reef rim control using open channel flow theory analytical relationships are derived for the reef top current velocity in terms of the offreef wave conditions the reef top water depth and the physical characteristics of the reef top topography the wave set up and wave generated flow relationships are found to predict experimental values with reasonable accuracy in most cases the analytical relationships are used to investigate wave generated flows into a boat harbour channel on heron reef in the southern great barrier reef c 2005 elsevier b v all rights reserved

subsidence analysis and modelling of the roer valley graben se netherlands abstract the roer valley graben southeastern netherlands forms the most northern branch of the european cenozoic rift system sedimentary backstripping of exploration wells provides control on vertical tectonic motions during the complex post paleozoic geodynamic evolution of the area the roer valley graben evolved by repeated reactivation of permo carboniferous fracture systems at least three episodes of extension related subsidence are recorded these occurred during the late permian early triassic 255 240 ma the middle jurassic 168 165 ma and the late cenozoic 36 0 ma a late jurassic early cretaceous stretching phase is weakly inferred from incomplete data crustal stretching values calculated from the tectonic subsidence curves can account for the reflection seismic controlled crustal configuration of the roer valley graben area results demonstrate a close relationship between the roer valley graben and the basins in the north sea during the mesozoic in contrast the cenozoic evolution of the roer valley graben is independent from that of the north sea and is related to the development of the rhine graben

wave driven circulation of a coastal reef lagoon system abstract the response of the circulation of a coral reef system in kaneohe bay hawaii to incident wave forcing was investigated using field data collected during a 10 month experiment results from the study revealed that wave forcing was the dominant mechanism driving the circulation over much of kaneohe bay as predicted theoretically wave setup generated near the reef crest resulting from wave breaking established a pressure gradient that drove flow over the reef and out of the two reef channels maximum reef setup was found to be roughly proportional to the offshore wave energy flux above a threshold root mean square wave height of 0 7 m at which height setup was negligible on the reef flat the wave driven currents increased approximately linearly with incident wave height however the magnitude of these currents was relatively weak typically 20 cm s 1 because of i the mild fore reef slope of kaneohe bay that reduced setup resulting from a combination of frictional wave damping and its re

mass transfer limitation of nutrient uptake by a wave dominated reef flat community maximum rates of phosphate nitrate and ammonium uptake by a reef flat community were estimated from rates of frictional dissipation that were calculated from the attenuation of waves propagating over the kaneohe bay barrier reef flat time averaged flow speeds across the entire study area ranged from 0 08 to 0 22 m s 21 observed decreases in wave energy fluxes and near bottom orbital velocities gave a mean estimate for the bottom friction coefficient cf of 0 22 6 0 03 friction coefficients were used to estimate nutrient mass transfer coefficients of 5 9md 21 for phosphate and 9 16 m d 21 for ammonium and nitrate wave heights offshore of kaneohe bay were also used to estimate an annual phosphate mass transfer coefficient of 8 6 2md that was determined from measured changes in phosphate concentrations across the reef flat we conclude that rates of phosphate uptake by the kaneohe bay barrier reef flat community are occurring near the limits of mass transfer net primary production is a major pathway by which mass and energy flow into coral reef ecosystems the uptake of dissolved nutrients is often the rate limiting step for net pri mary production in marine ecosystems thus a knowledge of the kinetics of nutrient uptake by coral reef communities is necessary for assessing how nutrient loading rates change in response to natural or anthropogenic increases in nutrient concentrations bilger and atkinson 1992 proposed that nutrient uptake by shallow reef communities was limited by mass transfer the physical transfer of nutrients across con centration boundary layers covering the surfaces of reef au totrophs these authors used mass transfer correlations for rough surfaces taken from the engineering literature to cor relate maximum rates of nutrient uptake with the frictional characteristics of experimental reef communities subse quent studies demonstrated the ability of such mass transfer correlations to predict nutrient uptake kinetics for experi mental reef communities within closed recirculating flumes atkinson and bilger 1992 bilger and atkinson 1995 thomas and atkinson 1997 and a large experimental me socosm atkinson et al 2001 the results of these studies made it clear that shallow water reef communities are ca pable of taking up nutrients from the water column at rates that are limited by mass transfer however it had not yet been demonstrated whether in situ rates of nutrient uptake

vertical variations of coral reef drag forces modeling flow in a coral reef requires a closure model that links the local drag force to the local mean velocity however the spatial flow variations make it difficult to predict the distribution of the local drag here we report on vertical profiles of measured drag and velocity in a laboratory reef that was made of 81 pocillopora meandrina colony skeletons densely arranged along a tilted flume two corals were ct scanned sliced horizontally and printed using a 3 d printer drag was measured as a function of height above the bottom by connecting the slices to drag sensors profiles of velocity were measured in between the coral branches and above the reef measured drag of whole colonies shows an excellent agreement with previous field and laboratory studies however these studies never showed how drag varies vertically the vertical distribution of drag is reported as a function of flow rate and water level when the water level is the same as the reef height reynolds stresses are negligible and the drag force per unit fluid mass is nearly constant however when the water depth is larger reynolds stress gradients become significant and drag increases with height an excellent agreement was found between the drag calculated by a momentum budget and the measured drag of the individual printed slices finally we propose a modified formulation of the drag coefficient that includes the normal dispersive stress term and results in reduced variations of the drag coefficient at the cost of introducing an additional coefficient

post variscan evolution of the lithosphere in the rhine graben area constraints from subsidence modelling in the area of the cenozoic rhine rift system crustal and lithospheric thicknesses range between 24 and 35 km and 60 and 120 km respectively this rift system transects the deeply truncated variscan orogen and superimposed permo carboniferous wrench induced troughs and late permian and mesozoic thermal sag basins at the time of its westphlian consolidation the variscan orogen was probably characterized by 45 60 km deep crustal roots that were associated with its rheno hercynian saxo thuringian saxo thuringian bohemian and bohemian moldanubian sutures all of which are transected by the cenozoic rhine rift system during the stephanian early permian wrench induced disruption of the variscan orogen subducted lithospheric slabs were detached causing upwelling of hot mantle material during the resulting thermal surge partial delamination and or thermal thinning of the continental mantle lithosphere induced regional uplift at the same time the variscan orogenic roots were destroyed and crustal thicknesses reduced to 28 35 km in response to the combined effects of mantle derived melts interacting with the lower crust regional erosional unroofing of the crust and on a more local scale by its mechanical stretching towards the end of the early permian the potential temperature of the asthenosphere returned to ambient levels with this regional long term thermal subsidence of the lithosphere commenced controlling the development of a new system of late permian and mesozoic thermal sag basins however the evolution of these basins was repeatedly overprinted by minor short term subsidence accelerations that reflect the build up of far field stresses related to rifting in the tethyan and atlantic domains comparison of observed and modelled subsidence curves suggests that in the area of the rhine rift system the lithosphere had equilibrated with the asthenosphere at the end of the cretaceous at depths of 100 120 km before it became thermally destabilized again by cenozoic rifting and plume related magmatism modelled subsidence curves indicate that by the end of early permian times the thermal thickness of the remnant mantle lithosphere ranged between 10 and 50 km in areas that were later incorporated into mesozoic thermal sag basins this corresponds to mid permian thermal lithosphere thicknesses of 40 80 km the geological society of london 2004

episodic circulation and exchange in a wave driven coral reef and lagoon system we examined the role of wave driven circulation relative to wind and buoyancy forcing in a coral reef lagoon system circulation measurements in paopao bay moorea french polynesia during austral summer show the importance of waves in driving flows over the reef crest through the lagoon and out the reef pass tides were comparatively weak due to proximity to amphidromic points and exhibited an unusual spring neap cycle where the major lunar tide modulated the major solar tide and the overall tidal phase stayed approximately constant wind had only a secondary effect compared to surface waves a simple fluid mass balance indicated rapid flushing of the shallow back reef and export through the reef pass and a reef capture zone width of 2 3 km the reef pass circulation dynamics exhibited two layer baroclinic exchange flow when waves were small which was suppressed during large wave events the unusually weak tidal forcing provided an opportunity to more closely investigate wave driven circulation dynamics as expected theoretically there was a wave driven setup of the free surface across the shallow lagoon which drove a highly frictional flow evident by a large drag coefficient cp 0 1 diverging from extant theory the observed setup varied strongly with significant wave height and period overall the circulation and exchange between this coral reef system and the adjacent open ocean were largely determined by episodic remote forcing events and differed significantly from periodic tidal exchange mechanisms

flow inside a coral colony measured using magnetic resonance velocimetry the velocity field within scale models of branching coral stylophora pistillata colonies was measured using magnetic resonance velocimetry mrv the models were based on digital representations of real coral skeletons derived using x ray computed tomography ct and constructed using rapid prototype manufacturing two morphologies of s pistillata from the red sea grown in different flow regimes were used to simplify visualization of the data velocities were parsed into a series of spherical shells giving the velocity distributions as functions of distance from coral center for both morphologies the low flow morphology distributed flow velocity relatively evenly throughout the interior in contrast the high flow morphology showed a wider range of velocities with regions of flow channeling and flow stagnation

jewish cemetery in hamburg altona germany state of marble deterioration and provenance several highly ornamented marble tombstones from the jewish cemetery in hamburg altona were investigated concerning their state of preservation and their provenance ultrasonic measurements were performed on site and on drill cores in the laboratory for the determination of the rock decay the investigations show that the predominantly strong decay of the marbles can only be determined exactly in the laboratory since on site the influence of water leads to an increase of ultrasonic velocities the water content has to be taken into account when dealing with ultrasonic analysis in addition to the rock fabric investigations geochemical analysis of the stable isotopes of carbon and oxygen as well as the major and trace elements were used to identify the provenance all the information gathered in this study points to the quarries of carrara as the rock source

the tectonic evolution of the southern dutch north sea during the palaeogene basin inversion in distinct pulses abstract in this paper we discuss the response of a sedimentary basin to compressional reactivation of extensional faults in distinct pulses the inversion of the broad fourteens basin in the southern dutch north sea is used as a case study the first pulse of inversion occurred during the late mesozoic as a result of the sub hercynean phase a second pulse occurred during the mid palaeocene laramide phase a final inversion pulse occurred around the eocene oligocene boundary coinciding with the pyrenean tectonic event we reconstructed the stratigraphic and structural development of the area during the palaeogene in detail basic data are two 2d seismic surveys supported by 74 geophysical wireline logs on which newly constructed depth and thickness maps are based the reconstruction is aided by a quantitative subsidence analysis cessation of compression resulted in relaxation and tensional reactivation of faults caused differential subsidence inheritance of geological structures is a key element in the tectonic activity in the broad fourteens basin during the palaeogene tectonic movement during the palaeogene was always accommodated by reactivation of palaeozoic mesozoic faults the intensity of inversion in the southern north sea basin during the pyrenean phase appears much larger than previously noticed moreover the area affected by the inversion is much wider than during previous phases minor differences in the direction of the local stress field between the tectonic phases and by the deposition of a thick sedimentary succession during the periods of tectonic quiescence between the inversion phases can account for this

wave spectral energy variability in the northeast pacific 1 the dominant characteristics of wave energy variability in the eastern north pacific are described from noaa national data buoy center ndbc buoy data collected from 1981 to 2003 ten buoys at distributed locations were selected for comparison based on record duration and data continuity long period lp t 12 s intermediate period 6 t 12 s and short period t 6 s wave spectral energy components are considered separately empirical orthogonal function eof analyses of monthly wave energy anomalies reveal that all three wave energy components exhibit similar patterns of spatial variability the dominant mode represents coherent heightened or diminished wave energy along the west coast from alaska to southern california as indicated by composites of the 700 hpa height field the second eof mode reveals a distinct el nino southern oscillation enso associated spatial distribution of wave energy which occurs when the north pacific storm track is extended unusually far south or has receded to the north monthly means and principal components pcs of wave energy levels indicate that the 1997 1998 el nino winter had the highest basin wide wave energy within this record substantially higher than the 1982 1983 el nino an increasing trend in the dominant pc of lp wave energy suggests that storminess has increased in the northeast pacific since 1980 this trend is emphasized at central eastern north pacific locations patterns of storminess variability are consistent with increasing activity in the central north pacific as well as the tendency for more extreme waves in the south during el nino episodes and in the north during la nina

observations of spatial flow patterns at the coral colony scale on a shallow reef flat 1 although small scale spatial flow variability can affect both larger scale circulation patterns and biological processes on coral reefs there are few direct measurements of spatial flow patterns across horizontal scales 1 had similar spatial patterns to wakes while higher frequency variations 0 05 0 1 hz kc 1 had no observable spatial structure on the reef flat both drag and inertial forces exerted by coral colonies could have significant effects on flow but within different frequency ranges drag dominates for low frequency flow variations and inertial forces dominate for higher frequency variations including the wave band our scaling analyses suggest that spatial flow patterns at colony and patch scales could have important implications for both physical and biological processes at larger reef scales through their effects on forces exerted on the flow turbulent mixing and dispersion

spectral wave flow attenuation within submerged canopies implications for wave energy dissipation 1 communities of benthic organisms can form very rough surfaces canopies on the seafloor previous studies have shown that an oscillatory flow induced by monochromatic surface waves will drive more flow inside a canopy than a comparable unidirectional current this paper builds on these previous studies by investigating how wave energy is attenuated within canopies under spectral wave conditions or random wave fields defined by many frequencies a theoretical model is first developed to predict how flow attenuation within a canopy varies among the different wave components and predicts that shorter period components will generally be more effective at driving flow within a canopy than longer period components to investigate the model performance a field experiment was conducted on a shallow reef flat in which flow was measured both inside and above a model canopy array results confirm that longer period components in the spectrum are significantly more attenuated than shorter period components in good agreement with the model prediction this paper concludes by showing that the rate at which wave energy is dissipated by a canopy is closely linked to the flow structure within the canopy under spectral wave conditions wave energy within a model canopy array is dissipated at a greater rate among the shorter period wave components these observations are consistent with previous observations of how wave energy is dissipated by the bottom roughness of a coral reef

tectonostratigraphy of the nieuwerkerk formation delfland subgroup west netherlands basin the nieuwerkerk formation is a major lower cretaceous synrift and postrift fluvial unit in the west netherlands basin southwest netherlands that attains thicknesses in excess of 1 km in places a strong tectonic overprint on its deposition and a large degree of facies heterogeneity have complicated correlation and greatly hampered understanding reservoir and seal distribution within the unit the integrated application of fluvial sequence stratigraphic concepts with biostratigraphic dating and the correlation of cycles of changing accommodation to sediment supply ratio a s cycles on three dimensional 3 d seismic well log and core data have allowed a much improved understanding of reservoir facies distribution within the nieuwerkerk formation a major intraformational unconformity divides the nieuwerkerk formation into two members the lower of these the alblasserdam member is predominantly nonmarine and has a significant tectonic depositional overprint correlation within this member is dependent on the identification of base level transit cycles probably induced by pulses of tectonism the inclusion of 3 d seismic isopach data facilitates mapping thicknesses and reservoir properties of the alblasserdam member in areas with no well control the upper member the rodenrijs claystone member was deposited during the postrift stage and is predominantly a coastal plain succession biostratigraphic correlation proved useful in subdividing this unit and correlating key seismostratigraphic markers use of biostratigraphic and cyclostratigraphic correlation techniques allowed chronostratigraphically consistent reservoir maps to be made of the constituent members of the nieuwerkerk formation these maps exhibit localized nonmarine syndepositional basins alblasserdam member sand depocenters followed by gradual southward landward stepping of facies tracts of the rodenrijs claystone member above the intraformational unconformity the rodenrijs claystone member is capped by a marine transgression that terminated fluvial deposition in this part of the basin interestingly no major lacustrine facies have been identified in the fluvial units in the west netherlands basin rendering it somewhat anomalous among rift basins

connecting flow over complex terrain to hydrodynamic roughness on a coral reef abstractflow over complex terrain causes stress on the bottom leading to drag turbulence and formation of a boundary layer but despite the importance of the hydrodynamic roughness scale z0 in pr