spatangoid produced ichnofabrics bateig limestone miocene spain and the preservation of spatangoid trace fossils a spatangoid produced ichnofabric is described from the miocene bateig limestone se spain this ichnofabric is characterized by the dominant presence of large meniscate burrows bichordites produced by irregular echinoids this constitutes an unusual mode of occurrence for spatangoid bioturbation as their traces are most typically preserved in bases and tops of sandstone event beds in fact despite their important role as burrowers in modern settings that can be extended back to the early cretaceous based on their body fossil record spatangoid trace fossils scolicia and bichordites are comparatively rare several factors play an important role in their preservation mechanism of burrowing sediment characteristics early diagenesis and presence absence of deep tier burrowers spatangoid produced ichnofabrics such as those from the bateig limestone characterize depositional settings with intermittent deposition of event beds where there is an absence of deeper tier bioturbation

eastern mediterranean transient and reversal of the ionian sea circulation 1 maps of the remotely sensed absolute dynamic topography adt and sea surface temperature sst over the eastern mediterranean in the period june 1993 to june 2001 show a dramatic and sudden change in the sea surface structure this change which is presumably associated with the relaxation of the eastern mediterranean transient emt had taken place by the middle of 1997 and consisted of a complete reversal of the ionian upper layer circulation from anticyclonic to cyclonic in the emt phase sst and adt maps suggest enhanced communication between the ionian and the aegean basins as well as aegean waters spreading northward along the eastern ionian flank negative wind vorticity in the ionian suggests that the switch of the upper layer circulation from anticyclonic to cyclonic cannot be explained in terms of the wind forcing therefore we suggest the predominance of the baroclinic vorticity production term in determining the upper layer circulation inversion

palaeoecology and survival strategies of an impoverished benthic chalk community in a mid danian deep shelf setting abstract upper cretaceous chalk is characterized by a rich and diverse benthic fauna followed by a poor benthic fauna in the lowermost danian immediately after the k pg extinction event in the early to mid danian diversity increased and rich bryozoan and cold water coral mound ecosystems were established in localized areas in the contemporary mid danian dalbyover deep shelf chalk the benthic fauna is markedly impoverished the danian macrofauna from bulk samples at dalbyover comprises 22 species and several bryozoan morphogroups and is of low diversity and density compared to latest maastrichtian and mid danian shelf faunas average fischer alpha index is 2 34 and shannon index 1 38 with minor stratigraphic variations guild analysis of the macrofauna indicates that the vast majority of species show special adaptations to survival at and in the uppermost few centimetres of the soft substrate with dominance of root attached species attaching to small substrates and free lying suspension feeders further the morphology of the serpulid tubes and the occurrence of crinoids in situ reflect a stable substrate with little overturning by the infauna the benthic foraminiferal assemblages are dominated by low trochospiral and planispiral epifaunal morphogroups whereas elongated forms with an infaunal mode of life are rare the combined macrofauna and foraminiferal data indicate deposition in a relatively stable environment where food was a limiting factor for the macrofauna it is evident that species occurring in small numbers are long ranging and also known from the cretaceous whereas species occurring in high numbers are known solely from the danian evidently the mesozoic survivors had the strategy to survive in this special chalk environment where only few danian species were successful

mound forming cold water corals and bryozoans in the early palaeocene of denmark the faxe quarry in south east denmark offers excellent exposures of early palaeocene danian deep water intercalated coral and bryozoan mounds that form complexes at least 40 m thick and a few kilometres wide along and over submarine highs the co existing coral and bryozoan mounds represent two different biogenic carbonate factories with a highly dynamic interplay during growth the sedimentary facies mound geometries and the density diversity and palaeoecology of the associated benthic invertebrates and nannofossils allow recognition of six successive growth units unit 1 represents an outer shelf bryozoan mound belt characterized by an oligotrophic cool water nannofossil assemblage unit 2 comprises a mixed faunal assemblage of bryozoans and octocorals with an initial sparse colonization of hexacorals the nannofossil assemblage records a decrease in diversity and an increase in warm water forms unit 3 marks the onset of dense colonization of the scleractinian coral dendrophyllia candelabrum with associated low diversity macrofauna and nannofossil assemblages unit 4 represents the main coral build up phase with frame building hexacorals of dendrophyllia and faxephyllia associated with a high diversity invertebrate fauna and relatively low diversity nannofossil assemblages unit 5 represents the late coral mound phase showing extensive lateral distribution and finally death and erosion of the coral mounds this event was contemporaneous with a warming trend in the pelagic environment the succeeding unit 6 marks the burial and overgrowth of the coral mound complex by bryozoan rich sediments the coral mound complex in the faxe quarry initiated and terminated in global nannofossil zone np3 and regional nannofossil zones nntp2g 3 suggesting a mound growth duration of approximately 300 kyr and a mean vertical accretion of the coral mound of 13 cm kyr the mound complex probably serves as the best exposed analogue to modern deep and cold water coral mounds in the north atlantic this article is protected by copyright all rights reserved

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

benthic palaeoecology of danian deep shelf bryozoan mounds in the danish basin abstract early danian cool water bryozoan mounds exposed in the coastal cliff stevns klint in denmark were formed shortly after the cretaceous tertiary mass extinction they represent a relatively deep water highly diverse benthic ecosystem within the epeiric seaway that covered the danish basin the mounds are 50 110 m long and reached a height of about 5 10 m above the seafloor they are asymmetrical with a steep southern and a gentle northern flank and were dominated by small suspension feeders the benthic elements generally occur as fragments set in a carbonate mud matrix the main skeletal contributors are delicate branching bryozoans with minor contributions of bryozoan sheets and nodular arborescent bryozoans locally abundant octocorals occur on the mound crests and upper parts of the steep flanks echinoids are present in minor amounts but are locally abundant serpulids crinoids asteroids brachiopods bivalves massive calcareous sponges and benthic foraminifers are generally minor contributors to the benthic mound fauna influx of planktonic foraminifers coccoliths and other planktonic organisms was high and was probably a major source of nutrient supply to the mainly suspension feeding benthic fauna the faunal association reflects a relatively low energy environment with a high possibly seasonal influx of particulate nutrients the best growth conditions with respect to nutrient influx were on the mound crest and upper steep flank reflected by the diverse and relatively largest benthic faunal elements periodic reworking and winnowing occurred across the entire mound structure but most prominent on the gentle northern flanks limiting the benthic growth and notably the colony density and size of delicate branching bryozoans vagile benthic faunas were also adapted to different areas on the mound irregular echinoids preferred the intermound areas within fine grained wackestone packstone facies where they ploughed through the sediment whereas regular echinoids were epifaunal and preferred the upper parts of the mounds possibly feeding mainly on bryozoans skeletons of both groups became concentrated at the toe of the steep flanks and in the intermound areas by physical reworking during major storms changes in faunal composition on the mound crests occurred rhythmically on both small and large scale during mound growth rhythmically recurring faunal assemblages reflect alternating hydrodynamic conditions on the seafloor with respect to nutrient influx and energy which probably were linked to short term seasonal and long term climatic variations the long term alternation may be within the milankovitch frequency band blooming events of bryozoan sheets resulted from relatively short periods with large amounts of available food and suitable substrate successful colonisation by octocorals on the other hand reflected longer term favourable conditions on the mounds possibly associated with overall higher energy levels a possible pleistocene analogue to the bryozoan dominated danian mounds occurs at the shelf slope break of the great australian bight both of these cool water mound systems deviate from most other biogenic mounds known from the fossil record in their non cemented nature regular geometry and a lack of core and flank facies

mediterranean thermohaline response to large scale winter atmospheric forcing in a high resolution ocean model simulation large scale circulation anomalies over the north atlantic and euro mediterranean regions described by dominant climate modes such as the north atlantic oscillation nao the east atlantic pattern ea the east atlantic western russian eawr and the mediterranean oscillation index moi significantly affect interannual to decadal climatic and hydroclimatic variability in the euro mediterranean region however whereas previous studies assessed the impact of such climate modes on air sea heat and freshwater fluxes in the mediterranean sea the propagation of these atmospheric forcing signals from the surface toward the interior and the abyss of the mediterranean sea remains unexplored here we use a high resolution ocean model simulation covering the 1979 2013 period to investigate spatial patterns and time scales of the mediterranean thermohaline response to winter forcing from nao ea eawr and moi we find that these modes significantly imprint on the thermohaline properties in key areas of the mediterranean sea through a variety of mechanisms typically density anomalies induced by all modes remain confined in the upper 600 m depth and remain significant for up to 18 24 months one of the clearest propagation signals refers to the ea in the adriatic and northern ionian seas there negative ea anomalies are associated to an extensive positive density response with anomalies that sink to the bottom of the south adriatic pit within a 2 year time other strong responses are the thermally driven responses to the ea in the gulf of lions and to the eawr in the aegean sea moi and eawr forcing of thermohaline properties in the eastern mediterranean sub basins seems to be determined by reinforcement processes linked to the persistency of these modes in multiannual anomalous states our study also suggests that nao ea eawr and moi could critically interfere with internal deep and abyssal ocean dynamics and variability in the mediterranean sea

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

ichnological analysis of pleistocene sediments from the iodp site u1385 shackleton site on the iberian margin approaching paleoenvironmental conditions ichnological analysis focused on trace fossil assemblages and an ichnofabric approach with special attention to cross cutting relationships tiering relative abundances and bioturbation degrees has been used to assess environmental parameters affecting the pleistocene macrobenthic tracemaker community at the iodp expedition 339 site u1385 shackleton site on the iberian margin the trace fossil assemblage consists of abundant planolites frequent yet sparsely distributed palaeophycus thalassinoides and thalassinoides like structures and taenidium and localized zoophycos and chondrites other ichnotaxa such as phycosiphon and scolicia are rare this assemblage is typical of the zoophycos ichnofacies though the distal expression of the cruziana ichnofacies has a similar composition ichnofabrics reveal variable substrate colonization with well defined cross cutting relationships and tiering distribution differentiated ichnofabrics are green mottled ichnofabric planolites ichnofabric taenidium and planolites ichnofabric thalassinoides like and palaeophycus ichnofabric planolites and thalassinoides thalassinoides like ichnofabric zoophycos ichnofabric and chondrites ichnofabric usually showing gradual transitions a multi tiered assemblage can be envisaged with differentiation of the shallowest biodeformational structures shallow planolites palaeophycus and even taenidium middle thalassinoides thalassinoides like structures and lower zoophycos and chondrites tiers according to the ichnological data a general context of good bottom and pore water oxygen conditions and organic matter availability can be interpreted but localized dysaerobic intervals might be related with the record of zoophycos and chondrites a constant rate of sedimentation shows only minor variations as revealed by ichnofabric succession soupy soft and stiffgrounds are interpreted as inducing changes in ichnological features salinity and temperature have a minor incidence on the macrobenthic tracemaker community causing only small changes in the trace fossils

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

diagenesis of spiculites and carbonates in a permian temperate ramp succession tempelfjorden group spitsbergen arctic norway this paper explores little investigated diagenesis of spicule dominated sediments based on permian spiculites and cool water carbonates of the tempelfjorden group in central spitsbergen field observations petrography stable isotope geochemistry and mineralogical and chemical analyses reveal that the strata have been subjected to multistage diagenesis as the result of silica phase transitions at medium burial depths and deep burial overprinting the growth of silica concretions occurred during the opal a opal ct conversion and was controlled by the content and distribution of clay and spicules in the sediment resulting in a variety of megascopic silica fabrics opal ct was subsequently dissolved and all silica is now in a stable quartz stage petrographically the rocks are characterized by a variety of chalcedony and quartz cements which perfectly preserve precursor textures most cements precipitated from silica oversaturated fluids and their shapes reflect the silica saturation state and geometry of the pore space some microquartz and cryptoquartz also formed by a solid solid inversion recrystallization of chalcedony the cements have 18o values between 30 and 20 standard mean ocean water and display a systematic depletion in 18o from the first to the last crystallized interpreted to reflect gradual increase in temperature during burial the precipitation of quartz cements started in the middle triassic when the strata passed the 19 c isotherm at burial depths of ca 600 m and was completed in the mid cretaceous 2 3 km beneath the sea floor at temperatures of 75 c late diagenetic overprinting of the chert includes fracturing brecciation and cementation with carbonate cements having 18o values between 2 and 30 pee dee belemnite and 13c values between 4 and 14 pee dee belemnite they are linked to hot solutions introduced during cretaceous volcanism or palaeogene tectonism this study illustrates the diagenetic pathway during burial of spicule rich sediments in a closed system and thereby provides a baseline for studies of more complexly altered chert deposits this article is protected by copyright all rights reserved

an epeiric ramp low energy cool water carbonate facies in a tertiary inland sea murray basin south australia the murray supergroup records temperate water carbonate deposition within a shallow mesotrophic oligo miocene inland sea protected from high energy waves and swells of the open ocean by a granitic archipelago at its southern margin rocks are very well preserved and exposed in nearly continuous outcrop along the river murray in south australia most facies are rich in carbonate silt contain a background assemblage of gastropods especially turritellids and infaunal bivalves and are packaged on a decimetre scale defined by firmground and hardground omission surfaces bioturbation is pervasive and overprinted resulting in rare preservation of physical sedimentary structures facies are grouped into four associations large foraminiferan bryozoan echinoid bryozoan mollusc and clay facies interpreted to represent shallow water 50 m deposition under progressively higher trophic resource levels from low mesotrophy to eutrophy and restricted marine conditions from relatively offshore to nearshore regions a large scale shift from high to low mesotrophic conditions within lower miocene strata reflects a change in climate from wet to seasonally dry conditions and highlights the influence terrestrially derived nutrients had upon this shallow land locked sea overall low trophic resource levels during periods of seasonally dry climate resulted in a deepening of the euphotic zone a widespread proliferation of foraminiferan photozoan fauna and a relatively high carbonate productivity inshore heterozoan facies became progressively muddier and restricted towards the shoreline in contrast periods of wet climate led to rising trophic resource levels resulting in a shallowing of the euphotic zone a decrease in epifaunal and seagrass cover and widespread development of a mostly heterozoan biota dominated by infaunal echinoids rates of carbonate production and accumulation were relatively low the murray basin is best described as an epeiric ramp wide facies belts developed in a shallow sea on a low angled slope reaching many hundreds of kilometres in length grainy shoal and back barrier facies were absent internally generated waves impinged the sea floor in offshore regions and because of friction along a wide and shallow sea floor created a low energy expanse of waters across the proximal ramp storms were the dominating depositional process capable of disrupting the entire sea floor

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

the western mediterranean deep water a proxy for climate change reconstructions of mediterranean ocean temperature fields back to 1950 show a proxy relationship between heat content changes in the north atlantic and the western mediterranean deep water wmdw formed in the gulf of lions in winter because of consistent air sea heat fluxes over these areas strongly correlated to the north atlantic oscillation nao

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

diagenesis of flint and porcellanite in the maastrichtian chalk at stevns klint denmark abstract flint is common in many successions but since the nodules can be the result of a series of replacement and void filling processes their origin and broader paleo oceanographic significance can remain enigmatic this study addresses the origin of flint in the campanian maastrichtian chalk of denmark using the 450 m long stevns 1 core as a natural laboratory four types of siliceous nodules occur in the core porcellanite white flint white flint with a core of dark flint and dark flint all nodules consist mainly of microquartz with subordinate lutecite spherulitic chalcedony megaquartz and dolomite the lutecite replaces macrofossil fragments mainly bryozoans and shells microquartz replaces coccoliths and the chalcedony and megaquartz are pore filling the preservation of the external shape of bryozoans shells and coccoliths suggest that siliceous nodules were formed early by a one by one volume replacement of chalk values of 18osmow of microquartz and lutecite around 33 indicate temperatures of 15 17 c at the time of precipitation in contrast the 18osmow values of megaquartz indicate precipitation at temperatures up to 48 c the occurrence of chalcedony together with more stable and ordered megaquartz in irregular voids indicates that silica gel and or opal ct transformed to the quartz phases microquartz lutecite chalcedony and megaquartz through the dissolution precipitation process ostwald ripening these results motivate a conceptual model in which the replacement process was initiated by microbial decomposition of organic matter and took place during periods of low rate of or even stopped sedimentation which fixed the redox boundary and the microbial metabolic zones at a specific depth below the sea floor biogenic opal a incorporated in the sediment column below the sea floor was dissolved and precipitated at the redox boundary as silica gel and or opal ct possibly aided by sulfide oxidizing bacteria during burial the dissolution precipitation process transformed the silica gel and opal ct to the quartz phases the results of this study indicate that precipitation of the flint precursor can be controlled by a combination of an abundant biosiliceous source and high microbial activity in the sediments immediately below the seafloor flint is therefore likely to reflect deposition in a narrow interval at relatively shallow depths and therefore might be useful in studies of shallow water carbonates

the former presence of organic matter caused its later absence burn down of organic matter in oceanic red beds enhanced by bioturbation eocene variegated shale carpathians eocene oceanic red beds that formed in a well oxygenated setting at low sedimentation rates below the calcite compensation depth are effectively barren of organic carbon in the present state recurrent distal low erosive turbidites preserve the bioturbated zone underneath that documents seasonal and long term fluctuating accumulation of considerable amounts of organic matter on the sea floor as evidenced by scolicia the producers of this trace fossil exploited nutritious organic matter conserved in turbidite buried sea floor deposits over the long term slow average sedimentation of hemi pelagic oxic red mud led to long oxygen exposure times and low burial of organic matter consequently trace fossils representing persistent sediment feeding modes are of small size although the food limited setting appears appropriate for producers of graphoglyptids such stationary burrows have not been encountered because seasonal deposition of organic matter fostered at least temporary surface layer feeding organisms for instance producers of nereites irregularis that intensively reworked the sediment and hence hindered graphoglyptid production these findings confirm palaeoceanographic modelling results that suggest upwelling in the study area during the eocene this article is protected by copyright all rights reserved

unexpected covariant behavior of the aegean and ionian seas in the period 1987 2008 by means of a nondimensional sea surface height index

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

meiobenthic trace fossils comprising a miniature ichnofabric from late permian carbonates of the oman mountains abstract an ichnofabric composed of meiobenthic trace fossils is described from late permian shelf carbonates of the arabian platform from the oman mountains saiq formation akhdar group it mainly consists of an 8 10 cm deep boxwork with an undulating burrow outline with an average burrow diameter of about 0 5 mm the pinch and swell like features lead to bulbous enlargements and alternating blade like contractions and are diagnostic for virgaichnus undulatus igen et isp nov in the upper tier of the ichnofabric v undulatus is associated with miniature spreiten like lobes which originate from a vertical shaft these circular elliptical or elongated lobes in the centimetre range consist of irregularly arranged probes less than 1 mm in diameter and are assigned to hydrancylus isp the assessment of burrowing mechanism burrow complexity burrow size and geological age indicates worm like organisms as potential trace makers for v undulatus the undulating shape of the burrow segments is in agreement with a peristaltic movement of a non segmented highly deformable vermiform body as known from nemerteans the presented case demonstrates that morphology in combination with size is invaluable for the interpretation of the trace maker and consequently strengthens the importance of meiobenthic trace fossils for palaeoenvironmental and facies analysis

trace fossil model for reconstructing oxygenation histories of ancient marine bottom waters application to upper cretaceous niobrara formation colorado abstract trends of decreasing trace fossil diversity burrow size and penetration depth with diminishing oxygen availability in contemporary marine settings have been incorporated with the concept of trace fossil tiering to develop a model for reconstructing the oxygenation history of ancient basin bottom waters more sensitive than traditionally employed criteria the model permits detailed evaluation of relative degree of oxygenation through the recognition of oxygen related ichnocoenosis ori units or units of strata deposited under similar levels of bottom water oxygenation when employed in detailed vertical sequence analyses the model may also be used to construct interpreted oxygenation curves that reflect rates and magnitudes of temporal change in redox conditions the utility of the model is demonstrated by its application to rhythmically bedded calcareous strata of the niobrara formation upper cretaceous exposed in colorado non laminated strata of the niobrara are characterized by four recurring trace fossil suites referred to as the 1 chondrites 2 zoophycos teichichnus 3 planolites and 4 thalassinoides assemblages on the basis of trends in trace fossil diversity burrow diameter and penetration depth these assemblages are recognized as oxygen related ichnocoenoses interpreted oxygenation curves for the basal fort hays member reflect high magnitude redox cycles characterized by rapid deoxygenation events followed by gradual reoxygenation phases curves for the overlying smoky hill member reflect an overall lower degree of oxygenation with more irregular lower magnitude redox fluctuations significant correlation between interpreted levels of paleooxygenation and organic carbon content illustrate the model s potential for evaluating the distribution of organic rich fine grained strata co interpretation of these variables with carbonate content supports the premise that deposition was controlled by paleoceanographic perturbations modulated by milankovitch like climatic cycles comparison with traditionally emphasized macroinvertebrate body fossil criteria clearly demonstrates the greater utility of the trace fossil approach for evaluating paleo oxygenation

stratal geometries facies and sea floor erosion in upper cretaceous chalk normandy france unusual lenticular stratal geometries and facies of the upper cretaceous chalk of coastal haute normandie france are described and interpreted thirteen facies within these chalks are described and illustrated on the basis of field thin section and sem investigations nannofossil mudstones nannofossil hardgrounds echinoderm wackestones and packstones echinoderm hardgrounds bryozoan mudstones and wackestones bryozoan hardgrounds bryozoan packstones and wackestones inoceramid wackestones inoceramid hardgrounds sponge hardgrounds marly chalks conglomeratic chalks and debris flow chalks these facies occur within lenticular bedded structures with both concave up and concave down geometries which have been previously interpreted as megaripples mud mounds or tectonic structures detailed examination of the structures and the associated facies indicates that the concave up geometries were formed from submarine erosion and redeposition in nw se longitudinal channels the concave down geometries developed between adjacent channels assessment of the regional and temporal setting indicates that the erosion occurred in the armorican cornubian straits of the anglo paris basin during sea level lowstands within these straits channelling is preferentially developed on the positive south western block to the lillebonne fecamp cotentin fault

two bioerosion ichnofacies produced by early and late burial associated with sea level change in bioerosion as in trace fossils as a whole deeply emplaced structures have greater survival value than shallow structures that is to say tiering the relative depth to which rasping etching and boring organisms penetrate their substrate is of paramount importance for the preservation potential of individual trace fossils an entobia ichnofacies is established for trace fossil assemblages dominated by deep tier borings and arising from long term bioerosion such as occurs on sediment free submarine cliffs or hardgrounds a gnathichnus ichnofacies comprises assemblages containing all tiers including superficial sculptures produced by radulation that have very little preservation potential such assemblages occur in short term bioerosion situations as on shell surfaces and hardgrounds buried early by sedimentation

geologic characterization of the type cored section for the upper cretaceous austin chalk group in southern texas a combination fractured and unconventional reservoir a rock based geologic characterization was completed on a continuous core through the austin chalk group section an active exploration target in southern texas because this core located in the pearsall field is continuous and includes both lower and upper contacts it can be used as the type cored section for the southern texas austin chalk several general lithofacies are defined two lithofacies lithofacies 1 and 2 are highly bioturbated and have low to moderate organic matter content and are poor to moderate source rocks two other lithofacies lithofacies 3 and 4 are laminated lithofacies 3 containing some burrows and lithofacies 4 containing no burrows both lithofacies are good source rocks organic matter in the laminated lithofacies 3 and 4 and some of the organic matter in the bioturbated lithofacies 2 are dominated by type ii kerogen suggesting the section can be self sourcing a general trend is observed whereby lithofacies that were deposited under more oxygenated conditions increase in abundance up section and is related to a decrease in total organic carbon and hence source rock quality the primary oil and gas production is from fractures with possible later production from the nano to microporous matrix after pressure drawdown pore types are predominantly interparticle nano to micropores and lesser intraparticle nanopores as defined by loucks et al 2012 porosity is less than 8 and permeability is less than 0 05 md and ranges down into the nanodarcy range the type cored section adds to the understanding of the southern texas austin chalk by providing a geological description of lithofacies stacking patterns source rock quality characterization and reservoir quality the type core can be used as a comparison section to other cored sections of the austin chalk

tiering in suspension feeding communities on soft substrata throughout the phanerozoic tiering of benthic marine suspension feeding communities on soft substrata has varied throughout the phanerozoic epifaunal tiering was most developed during the middle and late paleozoic and the triassic to jurassic with large scale reductions in tiering occurring during the permian triassic extinctions and after the jurassic infaunal tiering reached its highest level of organization after the paleozoic

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

sedimentology and ichnology of the cretaceous tertiary boundary in denmark implications for the causes of the terminal cretaceous extinction abstract trace fossils and other sedimentologic evidence of bioturbation in latest cretaceous and earliest tertiary marine deposits in denmark provide important clues to understanding the ecology of the sea bottom immediately before during and after the terminal cretaceous boundary event trace fossil associations at all the onshore danish boundary sites indicate a general upward shoaling of the late maastrichtian chalk sea which was accompanied by an abrupt shift from a carbonate ooze sea floor to a marly clay rich unstable substrate at the boundary although the substrate condition may have become more stable in the early danian water depths never did return to their former deep level there is evidence of localized anoxia during the deposition of some boundary sediments in the fish clay in shallow parts of the danish maastrichtian sea but no clear evidence of anaerobic conditions occurring at the era boundary was observed in boundary strata deposited in deeper water near the center of the basin in fact earliest danian marl there is totally bioturbated a pulse of calcite dissolution in shallow water coincided precisely with the era boundary and this event played a major role in the formation of the fish clay in eastern denmark which is a condensed series of smectitic clay rich layers from which much calcite has dissolved the effects of this dissolution episode however were not so extreme in the marl that was deposited at the same time in slightly deeper water in northwestern denmark evidence from cretaceous tertiary boundary sequences in denmark and elsewhere suggests that no single catastrophe can account for the major biotic extinctions that occurred at the end of the cretaceous period the primary causal factors of the terminal cretaceous extinction event appear to be drastic global sea level regression occurring simultaneously with extensive volcanism on land and a strong pulse of calcite dissolution in ocean surface waters

sequence stratigraphy and ichnology of early cretaceous reservoirs gadvan formation in southwestern iran abstract the siliciclastic gadvan formation from abadan plain southwestern iran is highly bioturbated and allows relationships between changes in ichnocoenoses within a depositional system to be documented and placed in a high resolution sequence stratigraphic framework relying on the sedimentary and ichnological characteristics the siliciclastic succession is divided into two facies associations a wave dominated offshore shoreface complex and a tide river influenced delta the first includes facies that have been deposited in shelf offshore upper offshore lower shoreface and upper middle shoreface environments the latter includes facies that have been deposited in prodelta and delta front integrated ichnologic and sedimentologic studies of the gadvan formation allow distinction between prodelta and delta front and open marine deposits with the identification of maximum flooding and ravinement surfaces as bounding surfaces of the stratal units detailed analysis on systematic changes in the stacking pattern cycle thickness cycle type and facies proportion are made eight ichnocoenoses could be differentiated in the studied sections the positions of the ichnocoenoses within genetically related stratal units genetically related ichnocoenoses indicate three large scale cycles ds1 to ds3 from oldest to youngest the cyclical nature of the gadvan formation is attributed to low amplitude eustasy in greenhouse conditions formed under interaction of eustatic high frequency cycles and longer term tectonically driven sea level variations during the long term transgressive sea level trend of the early cretaceous stratigraphic architectural style of sequences ds1 to ds3 which includes scarce evidence of lowstand deposits partial or total truncation of the hst and predominance of thick transgressive deposits is remarkably similar to long term transgressive sea level trend of the early cretaceous across the arabian plate this study suggests a more relatively seaward position of the siliciclastic successions of the gadvan formation of abadan plain than the mesopotamian basin upper zubair formation equivalent in western iraq and kuwait which would be concordant with the prevailing view of an easterly prograding coastline across the arabian plate this study reveals important sedimentological and ichnological features and permits the development of predictive models for the paleoenvironmental and sequence stratigraphical significance of trace fossil assemblages that can be readily compared or translated to analogous depositional systems worldwide the ichnological analysis is based on cores and can be especially applied to evaluate the applicability of current ichnological models to the study of cretaceous reservoirs of western iraq kuwait and western saudi arabia

facies and ichnology of an upper cretaceous chalk contourite drift complex eastern denmark and the validity of contourite facies models the upper cretaceous chalk of the danish basin has been interpreted as a major contourite complex on the basis of high resolution seismic data the sea floor had a pronounced topography with kilometre wide ridges and valleys up to almost 200 m deep interpreted to have been formed by contour parallel bottom currents only few ancient contourite systems have been recognized mainly based on sedimentary facies and only rarely on architecture and morphology two cored boreholes 345 and 443 3 m deep through the danish chalk contourite complex offer a unique possibility to compare seismic and sedimentary facies the contourite chalk is completely bioturbated except for thin intraclast conglomerates and a few thin levels showing possible primary lamination in terms of lithology and trace fossils the contourite chalk is similar to horizontally bedded pelagic chalk uninfluenced by bottom currents published contourite models cannot normally be used for the chalk because of the very fine grain size generally complete bioturbation and lack of any vertical trends in grain size on a millimetre to centimetre scale it is thus only rarely possible to document the influence of bottom currents on the basis of facies analysis alone and this can be inferred only by architectural analysis of seismic scale outcrops

effects of the north sea caspian pattern on surface fluxes of euro asian mediterranean seas 1 the influence of the north sea caspian pattern ncp on marine basins of the euro asian mediterranean region mediterranean black and caspian seas is investigated by making use of empirical orthogonal functions eof analysis the effect of the ncp on surface fluxes of momentum and heat as well as on curl and divergence of wind stress is evident in all of the studied basins in particular the aegean and southern black sea heat fluxes are significantly affected by ncp the processes underlying the demonstrated effects of the ncp on the mediterranean sea deserve further attention especially as they relate to the so called eastern mediterranean transient emt a recent event that resulted in abrupt changes in the marine climate

chondrites a trace fossil indicator of anoxia in sediments the trace fossil chondrites a highly branched burrow system of unknown endobenthic deposit feeders occurs in all types of sediment including those deposited under anaerobic conditions in some cases such as the jurassic posidonienschiefer formation of germany chondrites occurs in black laminated carbonaceous sediment that was deposited in chemically reducing conditions in other cases such as numerous oxic clastic and carbonate units throughout the geologic column chondrites typically represents the last trace fossil in a biotutbation sequence this indicates that the burrow system was produced deep within the sediment in the anaerobic zone below the surficial oxidized zone that was characterized by freely circulating and oxidizing pore waters

observational constraints on the tropospheric and near surface winter signature of the northern hemisphere stratospheric polar vortex a composite analysis of northern hemisphere s mid winter tropospheric anomalies under the conditions of strong and weak stratospheric polar vortex was performed on ncep ncar reanalysis data from 1948 to 2013 considering as additional grouping criteria the coincidental states of major seasonally relevant climate phenomena such as el nino southern oscillation enso quasi biennial oscillation and strong volcanic eruptions the analysis reveals that samples of strong polar vortex nearly exclusively occur during cold enso states while a weak polar vortex is observed for both cold and warm enso the strongest tropospheric and near surface anomalies are found for warm enso and weak polar vortex conditions suggesting that internal tropospheric circulation anomalies related to warm enso constructively superpose on dynamical effects from the stratosphere additionally substantial differences are found between the continental winter warming patterns under strong polar vortex conditions in volcanically disturbed and volcanically undisturbed winters however the small size samples obtained from the multi compositing prevent conclusive statements about typical patterns dominating effects and mechanisms of stratosphere troposphere interaction on the seasonal time scale based on observational reanalysis data alone hence our analysis demonstrates that patterns derived from observational reanalysis time series need to be taken with caution as they not always provide sufficiently robust constraints to the inferred mechanisms implicated with stratospheric polar vortex variability and its tropospheric and near surface signature notwithstanding this argument we propose a limited set of mechanisms that together may explain a relevant part of observed climate variability these may serve to define future numerical model experiments minimizing the sample biases and thus improving process understanding

paleoecology of the marine endobenthos endobenthic animals which reside within the sea bottom include stationary suspension feeders mobile deposit feeders and both stationary and mobile carnivores their activities especially with regard to dwelling feeding walking crawling and resting nesting are recorded as trace fossils abundance diversity and density of some kinds of trace fossils allow interpretation of the population strategies of the trace makers in terms of opportunistic r selected and equilibrium k selected strategies opportunistic ichnotaxa tend to be faciesbreaking traces which are highly localized in low diversity high density trace fossil associations in rocks representing environmental extremes e g variable salinities harsh temperatures low oxygen levels or shifting substrates equilibrium ichnotaxa usually are restricted to particular sedimentary facies and are characteristic of high diversity low dominance trace fossil associations in sediments reflecting stable predictable environmental conditions the most important environmental factors influencing the composition of trace fossil assemblages in marine settings are bathymetry substrate oxygen and hydrodynamic energy the four factors are closely interrelated because as water depth increases there is a general decrease in sediment grain size and hydrodynamic energy of the depositional environment as depth below the water sediment interface increases the firmness of the sediment due to compaction and dewatering increases and the oxygen content of interstitial waters drops drastically marine ichnofacies are largely substrate controlled soupgrounds are water saturated incompetent substrates typified by highly compressed and usually unidentifiable burrows softgrounds commonly contain numerous distinctive burrows and are zoned bathymetrically by the skolithos cruziana zoophycos and nereites ichnofacies firmgrounds are characterized by stiff compacted sediments in which traces of the glossifungites ichnofacies are excavated hardgrounds are cemented substrates in which bioerosion traces of the trypanites ichnofacies are bored woodgrounds are woody materials that have been exposed to the sea and bored by bivalves which produce characteristic traces of the teredolites ichnofacies tiering of endobenthic communities is common and is related to substrate preference of the burrowers and oxygen stratification of interstitial waters

danian cool water bryozoan mounds at stevns klint denmark a new class of non cemented skeletal mounds abstract a laterally extensive danian early paleogene bryozoan mound complex is well exposed in 14 km of nearly continuous outcrop in the coastal cliff stevns klint in eastern denmark a nw se oriented seaway covered the danish basin in danian time it widened towards the nw where it passed into the deeper north sea basin and narrowed towards the se where it was connected with the polish trough the exposed mound succession is up to 20 m thick individual mounds are oval in plan view internally asymmetrical 5 11 m high 45 110 m long in nne ssw oriented dip sections parallel to the direction of mound migration and 50 300 m in strike sections the southern flanks are steep and dip 15 30 mainly towards the ssw whereas northern flanks have gentle dips of 0 15 towards the nne four facies associations are distinguished 1 the initial mound association consisting mainly of bryozoan packstone rudstone 2 the steep flank mound crest association consisting of bryozoan rudstone with subsidiary octocoral and encrusting bryozoan rudstone and bryozoan grainstone 3 the gentle flank association characterized by bryozoan packstone and incipient to fully developed hardgrounds and 4 the intermound association consisting of echinoid rudstone packstone and minor occurrences of bioclastic grainstone and argillaceous wackestone packstone beds and laminae facies analysis and mesoscale mapping indicate that the bryozoan mound complexes were formed in relatively deep cool water below the photic zone and swell wave base deposition was influenced by along slope currents with prominent seasonal and long term variations mound growth was governed by primarily in place benthic carbonate production of mainly delicate branching bryozoans which baffled and trapped pelagic and detrital benthic carbonate mud gentle currents rich in particulate nutrients flowing towards the wnw deflected by the coriolis force and possibly a tidally or wind induced upslope component towards the nne resulted in mound growth mainly towards the ssw high production in the surface waters combined with an effective tidally induced mixing of the water column was important for transporting particulate nutrients to the bottom waters periodic intensification of the mean wnw ward flowing bottom current system combined with a storm associated downslope component towards the ssw resulted in winnowing and erosion of the northern mound flanks long term periodic waning or cessation of bottom currents and possibly stratification of the water column resulted in very limited benthic carbonate production and mound growth associated with formation of extensive thalassinoides burrow galleries mirrored by the rhythmic occurrences of flint nodule bands mound development thus reflects the delicate balance between biogenic growth towards particulate nutrient carrying currents current winnowing and erosion the lack of framework buildup and the poorly cemented nature of the mounds is remarkable in this respect they deviate from most other mound types known from the geological record and may possibly together with the sub recent analogues on the great australian bight represent a new class of noncemented skeletal mounds

transient eastern mediterranean deep waters in response to the massive dense water output of the aegean sea in the 1990s abstract we present a detailed account of the changing hydrography and the large scale circulation of the deep waters of the eastern mediterranean emed that resulted from the unique high volume influx of dense waters from the aegean sea during the 1990s and of the changes within the aegean that initiated the event the so called eastern mediterranean transient emt the analysis uses repeated hydrographic and transient tracer surveys of the emed in 1987 1991 1995 1999 and 2001 2002 hydrographic time series in the southern aegean and southern adriatic seas and further scattered data aegean outflow averaged nearly 3 10 6 m 3 s 1 between mid 1992 and late 1994 and was largest during 1993 when south and west of crete aegean influenced deep waters extended upwards to 400 m depth emt related aegean outflow prior to 1992 confined to the region around crete and to 1800 m depth wise amounted to about 3 of the total outflow outflow after 1994 up to 2001 2002 derived from the increasing inventory of the tracer cfc 12 contributed 20 to the total of 2 8 10 14 m 3 densities in the southern aegean sea deep waters rose by 0 2 kg m 3 between 1987 and 1993 and decreased more slowly thereafter the aegean waters delivered via the principal exit pathway in kasos strait east of crete propagated westward along the cretan slope such that in 1995 the highest densities were observed in the hellenic trench west of crete aegean influenced waters also crossed the east mediterranean ridge south of crete and from there expanded eastward into the southeastern levantine sea transfer into the ionian mostly followed the hellenic trench largely up to the trench s northern end at about 37 n from there the waters spread further west while mixing with the resident waters additional transfer occurred through the herodotus trough in the south levantine waters after 1994 consistently showed temperature salinity t s inversions in roughly 1000 1700 m depth with amplitudes decreasing in time the t s distributions in the ionian sea were more diverse one cause being added aegean outflow of relatively lower density through the antikithira strait west of crete spreading of the aegean influenced waters was quite swift such that by early 1995 the entire emed was affected and strong mixing is indicated by near linear t s relationships observed in various places referenced to 2000 and 3000 dbar the highest aegean generated densities observed during the event equaled those generated by adriatic sea outflow in the northern ionian sea prior to the emt a precarious balance between the two dense water source areas is thus indicated a feedback is proposed which helped triggering the change from a dominating adriatic source to the aegean source but at the same time supported the previous long year dominance of the adriatic the emed deep waters will remain transient for decades to come

stratigraphically controlled silicification in danian chalk and its implications for reservoir properties southern danish central graben abstract the effect of silica on reservoir quality in chalk is subject to continuing debate in particular the stratigraphic variations in silica content within the chalk matrix have not been addressed sufficiently in this study a new approach is applied to constrain silica variability in reservoir chalk utilizing hand held x ray fluorescence hh xrf on samples from four maastrichtian danian cores from hydrocarbon producing fields in the southern danish central graben the results indicate a significant lateral and stratigraphic variability in silica concentrations across the study area data display a common stratigraphic signature in all wells however with maximum silica concentrations and minimum porosities occurring in the lower part of the danian ekofisk formation correlation between hh xrf quantified silica concentrations and biostratigraphic data indicates the synchronous onset of an at least semi regional silica event during the mid danian nannofossil zones nntp2f g to nntp4a d whereas the upper boundary of the peak silica unit is poorly constrained generally stratigraphic trends in silica concentrations appear to be negatively correlated with porosity trends however comparison between the hh xrf quantified silica content and reservoir data porosity permeability estimated pore radius and calculated specific surface area shows poor correlation indicating that silica content within the ekofisk reservoir is not the only factor controlling the reservoir quality unknown complex diagenetic interactions between calcite silica and clay probably influence the reservoir properties by promoting calcite cementation in stratigraphically controlled zones making the ekofisk reservoir much less predictable than the underlying maastrichtian tor formation

can internal processes sustain reversals of the ocean upper circulation the ionian sea example 1 in 1997 an inversion in the ionian upper layer circulation was documented and ascribed to a massive inflow of aegean dense waters associated with the eastern mediterranean transient emt and not to the wind stress borzelli et al 2009 here we generalize the concept hypothesizing that such inversions are possible even in the absence of the aegean influence indeed salinity and density data collected in the southern adriatic the main source of the eastern mediterranean deep water show decadal variations coherent with changes in the sea level height in the northern ionian scaling considerations suggest that the redistribution of ionian water masses resulting from changes in the thermohaline properties of waters entering the basin can sustain inversions of the upper layer circulation therefore we propose a feedback mechanism named the adriatic ionian bimodal oscillating system bios between variations in the thermohaline properties of waters formed in the southern adriatic and the ionian circulation

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

danian cool water coral reefs in southern scandinavia localised over seafloor highs abstract danian paleocene reefs formed by ahermatypic scleractinian corals in relatively deep water are known in a few localities in southern scandinavia reflection and shallow seismic profiles and samples from drilling and scuba diving in bridge pier excavations in oresund the strait between denmark and sweden for the first time allow interpretation of the factors that controlled the localisation of the reefs after the mass extinction at the k t boundary reef building scleractinian corals were absent in the boreal early danian in the danish basin faunal evolution after the biotic crisis and a rise in relative sea level are interpreted to have favoured formation of deep water coral reefs in the oresund region in mid danian time the reefs were 6 20 m high and 20 200 m long on the seafloor and have a patchy distribution within a bryozoan mound dominated setting in an area of about 10 km 2 they are composed of the framework building ahermatypic scleractinian coral dendrophyllia candelabrum with minor occurrences of bryozoans echinoderms gastropods and bivalves it has been suspected that the reefs were located over contemporaneous seafloor highs but this notion was only based on comparison with similar modern deep water reefs offshore norway the data from oresund indicate that the danian reef complex was formed over a late maastrichtian palaeo seafloor high the saltholm malmo high supporting this interpretation and thus adding fundamentally to the understanding of the factors controlling the formation and localisation of these deep and cool water coral reefs individual reefs were initiated and grew on eroded crests and steep south dipping flanks of bryozoan mounds and were predominantly situated on the southern part of the high and are interpreted as growing towards nw flowing bottom currents rich in particulate nutrients

trace fossil analysis of lacustrine facies and basins abstract two ichnofacies are typical of lacustrine depositional systems the scoyenia ichnofacies characterizes transitional terrestrial nonmarine aquatic substrates periodically inundated or desiccated and therefore is commonly present in lake margin facies the mermia ichnofacies is associated with well oxygenated permanent subaqueous fine grained substrates of hydrologically open perennial lakes bathymetric zonations within the mermia ichnofacies are complicated by the wide variability of lacustrine systems detected proximal distal trends are useful within particular lake basins but commonly difficult to extrapolate to other lakes other potential ichnofacies include the typically marine skolithos ichnofacies for high energy zones of lakes and substrate controlled still unnamed ichnofacies associated to lake margin deposits trace fossils are useful for sedimentologic analysis of event beds lacustrine turbidites are characterized by low diversity suites reflecting colonization by opportunistic organisms after the turbidite event underflow current beds record animal activity contemporaneous with nearly continuous sedimentation ichnologic studies may also help to distinguish between marine and lacustrine turbidites deep marine turbidites host the nereites ichnofacies that consists of high diversity of ornate grazing traces and graphoglyptids recording highly specialized feeding strategies developed to solve the problem of the scarcity of food in the deep sea deep lacustrine environments contain the mermia ichnofacies which is dominated by unspecialized grazing and feeding traces probably related to the abundance and accessibility of food in lacustrine systems the lower diversity of lacustrine ichnofaunas in comparison with deep sea assemblages more likely reflects lower species diversity as a consequence of less stable conditions increase of depth and extent of bioturbation through geologic time produced a clear signature in the ichnofabric record of lacustrine facies paleozoic lacustrine ichnofaunas are typically dominated by surface trails with little associated bioturbation during the mesozoic bioturbation depth was higher in lake margin facies than in fully lacustrine deposits while significant degrees of bioturbation were attained in lake margin facies during the triassic major biogenic disruption of primary bedding in subaqueous lacustrine deposits did not occur until the cretaceous

texture composition and stratigraphy of volcanic ash beds in lower palaeocene chalk from the north sea central graben area a large number of volcanic ash beds have been identified in danian chalk from the danish north sea sector central graben area the volcanic input was prominent during deposition of the lower part of the danian chalk whereas it was much less during deposition of the upper part of the danian chalk the non carbonate fraction of the ash beds predominantly consists of smectite with some quartz illite and minor amounts of kaolinite chlorite and pyrite and trace amounts of zircon fragments of volcanic glass are common in the ash beds the mineralogical composition of the ash beds varies from bed to bed which makes ash bed correlation a promising high precision correlation tool volcanic provinces that were active in connection with the opening of the north atlantic ocean are possible sources of the volcanic ash the different composition of the ash layers could indicate that they originate from more than one source area

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

effects of a shallow flood shoal and friction on hydrodynamics of a multiple inlet system prior studies have shown that frictional changes owing to evolving geometry of an inlet in a multiple inlet bay system can affect tidally driven circulation here a step between a relatively deep inlet and a shallow bay also is shown to affect tidal sea level fluctuations in a bay connected to multiple inlets to examine the relative importance of friction and a step a lumped element parameter model is used that includes tidal reflection from the step the model is applied to the two inlet system of katama inlet which connects katama bay on martha s vineyard ma to the atlantic ocean and edgartown channel which connects the bay to vineyard sound consistent with observations and previous numerical simulations the lumped element model suggests that the presence of a shallow flood shoal limits the influence of an inlet in addition the model suggests an increasing importance of friction relative to the importance of the step as an inlet shallows narrows and lengthens as observed at katama inlet from 2011 to 2014

teleconnections force interannual to decadal tidal variability in the lagoon of venice northern adriatic 1 in the present investigation for the first time fundamental characteristics of autumn and winter average sequences of sea level heights slh that were recorded in the lagoon of venice northern adriatic in the mediterranean sea during the period 1872 2004 are investigated interannual to decadal variability of venetian slh is found to reflect the variability of the most prominent euro atlantic teleconnections eats in particular the north atlantic oscillation nao the east atlantic western russian and the scandinavian patterns are found to contribute to generate the 5 year 8 year and 22 year peaks that dominate the spectra of seasonal venetian slh among the possible oceanic and atmospheric phenomena downscaling interannual to decadal large scale atmospheric signals into the observed variability in the venetian slh we explore inverse barometer effect wind driven setup and the thermohaline circulation of both the adriatic and the mediterranean seas all these phenomena are assessed to display some of the typical features of the shared interannual to decadal variability of both venetian slh and eats our analysis shows also that the decadal variability of winter venetian slh is closely linked with variations in solar activity in particular the winter slh multidecadal pattern is found to be correlated with very high statistical confidence to the hale cycles pattern 22 years which describes the series of sunspot cycles with alternating opposite polarity the marked signature of hale cycles on the leading mode of multidecadal sea level pressure winter variability which is practically indistinguishable from the inverse wintertime nao is also detailed to further support the hypothesis of a sun venetian slh association

hydrographic characteristics of water masses and circulation in the northern ionian sea abstract the hydrography of intermediate and deep water masses in the northern ionian sea apulian plateau was studied through four quasi synoptic multidisciplinary surveys carried out in 2004 2006 as an ancillary oceanographic activity in the frame of the aplabes project this area plays a crucial role for the entire mediterranean basin being influenced by the water outflow of adriatic origin which under severe winter conditions is a primary source of dense water for the eastern mediterranean at the end of the 1980s such outflow showed a different behavior and only in the recent years has a gradual re establishing of the former condition been detected as such the adriatic sea has regained its role as a main source of the east mediterranean deep water which was temporarily inhibited during the well known eastern mediterranean transient which progressively modified the intermediate and deep layers of the mediterranean sea the general structure of water masses was similar through the investigated period but interesting differences within the bottom layer have been detected the interaction of the different water types present in the basin is reviewed by means of property property plots vertical sections isopycnal analyses and using an optimum multiparameter analysis omp which is an objective method to measure the mixing of water masses due to the lack of any direct information about the dynamics of the water column in the area of the apulian plateau during the whole analyzed period the classical method to infer the baroclinic velocity from the mass field has been applied to hydrographic data the well known indeterminacy of this method due to the barotropic component of the velocity field has been resolved using a short time series of current velocities acquired synoptically by a mooring located in the northern part of the studied area the wavelet transform was adopted for localizing and quantifying the variability of currents simultaneously in both frequency and time domains the presence of the adriatic deep water close to the bottom was detected on all four surveys with different signature as underlined by the objectively analysis with the optimum multiparameter analysis of the thermohaline field a core of cold less saline and oxygenated water of adriatic origin coming from the otranto channel was identified this water mass moved in geostrophic balance along the isobaths at 600 1000 m depth at the isopycnal surface of 29 18 kg m 3 not being dense enough to reach the deeper layers of the ionian basin carrying 0 27 0 36 sv

petrology and diagenetic changes of neogene siliceous rocks in northern japan abstract diagenetic changes in textures and mass properties of neogene marine noncalcareous siliceous rocks corresponding to silica phase transformations opal a opal ct quartz were studied in subsurface and surface sections of northern japan in opal a diatomite siliceous tests are well preserved no cementation is observable and pores exist chiefly as inter and intragranular micropores 2 10 during the opal a to opal ct transformation siliceous tests are extensively dissolved to form fine aggregates of opal ct in matrix and cement of opaline porcelanite an abrupt decrease of as much as 15 in porosity occurs between opal a and opal ct zones in subsurface sections a decrease which may be due to the destruction of intragranular pores in siliceous tests by dissolution ultramicropores 10 as molds and chambers of siliceous tests in quartzose porcelanite porosity of neogene noncalcareous siliceous rocks in subsurface sections of northern japan gradually decreases with the increase of burial depth and silica phase transformations have a relatively small effect on it this gradual decrease in porosity which corresponds well to that of neogene mudstone and clean fine grained sandstone indicates that little additional silica cementation occurs during burial iijima and tada 1981 at a depth of 4 5 km and a temperature of 130 c quartzose porcelanite holds porosity of 10 15 burial depth of around 10 km might be required to form dense quartzose chert without porosity by burial diagenesis of siliceous rocks if extrapolating from the burial depth porosity relation this depth is too large some additional mechanisms are required ther than mechanical compaction silica phase transformations and clay alteration pressure solution reprecipitation of quartz is the most probable one

late maastrichtian chalk mounds stevns klint denmark combined physical and biogenic structures abstract upper maastrichtian chalk exposed at the sigerslev quarry stevns klint denmark is characterized by wavy and mound like bedding geometries outlined by bands of black flint nodules four morphological elements are recognized although bedding geometries are highly variable southward migrating mounds eastward migrating mounds chalk waves and evenly bedded chalk the mounds are interpreted as having been formed by currents carrying fine grained suspended sediment which was primarily deposited on the up current mound flanks bryozoans were prolific on the up current flanks and mound summits which stabilized the mounds increased bed roughness and the overall accumulation rate however accumulation thicknesses do not correlate consistently with bryozoan density the bryozoans were therefore important for the formation of the mounds but the distribution of bryozoans did not solely determine depositional thickness across a mound and thus mound growth pattern relatively long wavelength wavy bedded chalk show gentle convex up geometries and would probably be described as sediment waves if recognized in seismic sections the chalk waves were deposited under weaker current velocities than those active during mound formation the exposed succession is topped by more evenly bedded chalk which was deposited by quiet pelagic fall out of fine grained material the whole succession was deposited on the upper part of the northern flank of a large wnw ese trending 3 km wide depositional ridge with an amplitude of 35 40 m formed by contour parallel wnw ward flowing bottom currents the mounds may have been deposited by regional bottom currents or by spill over currents from the valley south of the large ridge the succession was deposited during varying bottom current intensities and the depositional architecture indicates a complex and dynamic environment the depositional style seems to be controlled by the interplay and relative importance of two end member processes those that were purely physical and related to the interaction between available grain sizes and hydrodynamics and those that were largely biological and associated with benthic growth and sediment trapping of mainly bryozoans examples of end member conditions are known from haute normandy france and the lower danian of stevns klint the structures described here adds to the considerable complexity of depositional styles in chalk

burrowed matrix powering dual porosity systems a case study from the maastrichtian chalk of the gullfaks field norwegian north sea abstract chalk reservoirs are commonly modelled as dual porosity systems in which a very porous but low permeable matrix is intersected by highly permeable vugs and fractures from which oil and gas can be produced the gullfaks field in the norwegian north sea contains such a reservoir which is producing from maastrichtian chalk in addition to the conventional triassic and jurassic siliciclastic reservoirs however in comparison to the prolific chalk fields in the southern north sea e g ekofisk valhall chalk reservoirs in the northern part e g oseberg and gullfaks fields experience challenged production due to reservoir presence and quality related to depositional facies and structural conditions analyses of cores from three wells in the maastrichtian shetland group of the gullfaks field reveal that this interval is completely bioturbated during several stages e g mottling with diffuse bioturbated texture in an early softground stage that became subsequently overprinted by more discrete burrows with active and passive fill and different rock properties during the stiffground and firmground stages of the ooze a rich and moderately diverse trace fossil assemblage consists of abundant zoophycos common chondrites taenidium thalassinoides and virgaichnus and rare nereites planolites spirophyton and teichichnus ichnological features allow the differentiation of five recurrent ichnofabrics thalassinoides zoophycos chondrites nereites and zoophycos taenidium ichnofabrics with variable influence on porosity and permeability the thalassinoides ichnofabric in chalk has the highest impact on improving reservoir quality whereas zoophycos and partly chondrites ichnofabrics in marly chalk and chalky marlstone respectively contribute to creating potential reservoir zones if burrow density is high enough thin section analysis of the different ichnofabrics illustrates the negative or positive effect of burrows on porosity distribution whereas micro ct imaging reveals an intriguing system of partly open micro burrows e g virgaichnus within the matrix which serves as source for porosity this burrow porosity provides a connection in the matrix that hosts open vugs and fractures thus improving oil production

a possible influence of the north atlantic oscillation on the circulation of the western mediterranean sea a current time series spanning from 1985 to 1996 in the corsica channel shows that seasonal and interannual variabilities are stable components of the circulation of the northern part of the western mediterranean sea for the first time these characteristics are related to the state of the north atlantic oscillation during winter we have found that this large scale control is mainly maintained through the air sea interaction processes which take place in the northern basin these results provide new elements for a consistent explanation of the major features of the basin circulation such as the seasonal increase of the boundary current and deep water formation

composite ichnofabrics and tiering of burrows infaunal communities in marine environments typically are tiered that is different taxa live at different depths within the sediment tiered suites of biogenic structures yield complex biogenic sedimentary fabrics ichnofabrics with the traces of deep burrowing organisms overprinted on those of shallow burrowing organisms careful analysis of crosscutting relationships of burrows in such composite ichnofabrics allows reconstruction of the tiered nature of fossil endobenthic communities it is important to recognize that the best preserved and most prominently displayed trace fossils in most assemblages usually represent the deepest tier thus they were farther removed from the sea floor and therefore less indicative of actual sea floor conditions than the more poorly preserved traces of the shallower tiers on which the deeper traces are juxtaposed

relationships between tidal dynamics and bathymetry in strongly convergent estuaries abstract localized analytical solutions are derived for the propagation of a single predominant tidal constituent in estuaries with strongly convergent triangular cross sections the advective term is neglected and the friction term is linearized the solutions apply at any locality where the cross sectional shape remains sensibly congruent and the spatial gradient of tidal elevation amplitude is small i e synchronous then for specified tidal elevation amplitude and water depth d these solutions indicate values of tidal current amplitude u ratio of friction to inertial terms slope of the estuarine bed rate of energy dissipation and phase difference between and u illustrations of these results over a range of and d provide reference frameworks to assess observed conditions at any position in any estuary satisfying the criteria cited they may also indicate the range of parameters likely to be consistent with bathymetric equilibrium in dynamic sedimentary regimes the ratio of fr

bi decadal variability excited in the coupled ocean atmosphere system by strong tropical volcanic eruptions decadal and bi decadal climate responses to tropical strong volcanic eruptions sves are inspected in an ensemble simulation covering the last millennium based on the max planck institute earth system model an unprecedentedly large collection of pre industrial sves up to 45 producing a peak annual average top of atmosphere radiative perturbation larger than 1 5 wm 2 is investigated by composite analysis post eruption oceanic and atmospheric anomalies coherently describe a fluctuation in the coupled ocean atmosphere system with an average length of 20 25 years the study provides a new physically consistent theoretical framework to interpret decadal northern hemisphere nh regional winter climates variability during the last millennium the fluctuation particularly involves interactions between the atlantic meridional overturning circulation and the north atlantic gyre circulation closely linked to the state of the winter north atlantic oscillation it is characterized by major distinctive details among them the most prominent are a a strong signal amplification in the arctic region which allows for a sustained strengthened teleconnection between the north pacific and the north atlantic during the first post eruption decade and which entails important implications from oceanic heat transport and from post eruption sea ice dynamics and b an anomalous surface winter warming emerging over the scandinavian western russian region around 10 12 years after a major eruption the simulated long term climate response to sves depends to some extent on background conditions consequently ensemble simulations spanning different phases of background multidecadal and longer climate variability are necessary to constrain the range of possible post eruption decadal evolution of nh regional winter climates

taphonomy of ghost shrimps decapoda axiidea callianassidae associated with their burrows within a middle miocene mud volcano complex of persian arabian gulf kuwait abstract shallow marine strata of the ghar formation exposed along the kuwait arch in the north of kuwait contains fields of mud volcanoes associated with an assemblage dominated by pectinid bivalves and callianassid ghost shrimps the depositional palaeoenvironment is interpreted to be intertidal to subtidal with the water depth not exceeding 50 m and with normal to hypersaline conditions based on the microfossil assemblage a middle miocene age early langhian is inferred suggesting a longer stratigraphic span of the formation despite the previous studies treating the ghar formation as strictly early miocene callianassid body fossils and numerous trace fossils assignable to ophiomorpha have been identified ghost shrimp remains consisting of isolated cheliped elements are assigned to neocallichirus s l which is the likely producer of ophiomorpha burrows as documented by cheliped elements present within burrows and in the substrate around them stable isotopes discrimination modelling confirmed that fluids in the substrate were derived from at least two sources implying the presence of active mud volcanoes in the environment inhabited by ghost shrimps effusive activity of mud volcanoes further enhanced disarticulation and fragmentation of callianassid remains the micritic matrix of ghost shrimp exoskeletons is indicated to have resulted from a mixture of local seawater with fluid of continental origin this ghost shrimp occurrence is the first formal report of fossil decapod crustaceans from kuwait