modelling shoreface profile evolution current knowledge of hydro sediment and morpho dynamics in the shoreface environment is insufficient to undertake shoreface profile evolution modelling on the basis of first physical principles we propose a simple panel type model to map observed behaviour the internal dynamics are determined by slope dependent wave induced cross shoreface transports while the external driving factors are lateral sediment supply and sea level rise this model concept is tested with reasonable success against the observed behaviour of the central holland coast considering two hindcast periods one covering the evolution over the last century the other the subboreal subatlantic evolution a limitation of this model is that the cross shoreface dynamics are solely steered by the variations of shoaling short waves since a variety of other wave and current dynamics may be expected to be present in the coastal boundary layer it may well be that the effects of the mechanisms and conditions which are not represented are hidden in the coefficients of the sediment transport formula this limits the accuracy of the coefficients as used and our findings should be considered as an order of magnitude estimate only indeed behaviour oriented modelling implies that generalization of results to arbitrary situations and conditions is not straightforward yet we expect that some of the conclusions are more generally applicable this concerns the substantiation of the assumption that the upper shoreface responds on a much smaller time scale than the lower shoreface and the idea that the shoreface profile is not always and everywhere in equilibrium with its forcing a worthwhile observation from the holland coast application is that the bottom slope effect on the transport is only important at geological time scales the profile evolution at the engineering time scales say 10 to 100 years is effectively quasi static in that there is no feedback between the long term averaged transport and the state of the profile this implies that at these smaller scales the profile changes can be predicted on the basis of a static sediment balance this does not mean that the gravitational downslope transport is unimportant as a physical phenomenon in coastal profile evolution it is only unimportant if a highly aggregated model like this is applied at relatively short time scales

eemian early weichselian n s temperature gradients north atlantic nw europe abstract based on benthic marine organisms and or vegetation development at coastal sites in the eastern atlantic region temperature profiles of the last interglacial stage 5e and the early weichselian interstadial odderade stage 5a have been constructed from 40 to 80 degrees north the shape of the eemian summer temperature profile is very similar to the present but at all sites the eemian temperatures are a few degrees c warmer than present the odderade temperature conditions are very similar to the present both in the north on svalbard and in the south the nederlands france however in norway denmark and nw germany the odderade climate is much cooler than today sea surface temperature sst estimates inferred from planktonic foraminifera from the norwegian sea and the north atlantic show the same temperature trends as those inferred from the coastal sections these observations confirm the close relationship between western european climate and north atlantic surface conditions based on comparison between these temperature trends and insolation data we suggest that the development to an interstadial or interglacial type of climate in w europe is controlled by orbital forcing furthermore these results stress that quaternary stratigraphers working at high and low latitudes should be especially careful when using climatic inferences as a basis for correlation to interglacials or interstadials

deep sea carbonates reading the carbon isotope signal the carbon isotope signal in deep sea sediments reflects a mix of 1 global changes in the rates of exchange of the ocean s carbon reservoir with biosphere soil and sediments 2 global and regional changes in surface water productivity 3 internal shifts in water mass structure and circulation basin basin fractionation oxygen minimum development and 4 organism specific fractionation effects due to changes in micro habitat and or ontogenic fractionation vital effects additional complications arise from differential preservation it is impossible to entirely isolate these various factors as a rule of thumb long period signals that are parallel for planktonic and benthic data reflect external global fractionation patterns whilst short period signals are more likely tied to internal patterns water mass fractionation the various approaches to interpretation are illustrated with three case studies the glacial holocene transition the messinian carbon shift and the miocene monterey excursion

weichselian land sea interactions western norway norwegian sea abstract six major weichselian glacier expansions including the younger dryas are recorded in western norway three of the advances reached the continental shelf while the others were restricted to the coastal areas during the upper weichselian glacial maximum 18 20 ka there was an ice free corridor between the british and the scandinavian ice sheets in the northern north sea more or less complete deglaciation of southern norway seems to have happened some time around 90 and 70 ka large parts of the norwegian sea were at least seasonally open with influx of atlantic surface water in periods through isotope substage 5d to stage 4 possibly also during a short time interval close to the 2 3 boundary a small area in the southeastern norwegian sea was ice free all these influxes of atlantic water seem to correlate to periods with interstadial conditions in western norway during times with the most extensive continental glaciations there are no traces of any influx of atlantic surface water the western norwegian glacial record and the norwegian sea surface circulation record seem to vary with a ca 20 ka cycle during the weichselian this indicates a dominance of the precessional orbital forcing between the ca 100 ka interglacial glacial interglacial cycle

trace fossils biology and taphonomy 1990 special topics in palaeontology 3 280 pp e17 95 pbk e40 00 hbk unwin hyman london isbn 004445 6867 pbk 3035 hbk

paleoclimatology and paleoecology across the eocene oligocene boundary thrace basin northeast aegean sea greece abstract the detailed biostratigraphic and ichnological analysis of the upper eocene lower oligocene forearc sedimentary sequence in the southern greek part of the thrace basin on lemnos island reveals a relationship between eco sedimentary factors and the base level dynamics influencing calcareous nannofossils and trace fossil assemblages the lower part of the 350 m thick succession was deposited in a sand rich submarine fan system and upper part in a shelf environment it contains nannofossil assemblages and distributions typical of the np19 np21 biozones the eocene oligocene e o boundary top of np20 biozone is clearly distinguished within the upper parts of the turbidite system where a decrease in water temperature salinity nutrient supply and oxygenation level is also revealed additionally 19 ichnospecies mostly graphoglyptids typical of deep sea fan deposits have been distinguished the trace fossil diversity and abundance decrease upward reflecting the impact of the changing depositional environments from basin floor fans to slope systems and then shelfal environments the regional basin fill history rather than global climatic changes was probably the fundamental controlling factor on the distribution of graphoglyptids and other trace fossils across the e o boundary

beach morphology and shoreline evolution monitoring and modelling medium term responses portuguese nw coast study site abstract numerical models for shoreline evolution have been used for coastal management planning for several decades the model calibration is a start point to project shoreline scenarios and in this aim the use of data acquired within the scope of monitoring programmes provides the opportunity to assess the models capabilities under real condition this work applies calibration data retrieved from field surveys to numerical models to predict medium term shoreline evolution using as a case study a beach stretch named ac about 3 5 km long and located downdrift of a groin on the northwest portuguese coast a smaller stretch ab 2 4 km long included in the total one which exhibits a pronounced erosive tendency usually better reproduced in shoreline evolution models was also analysed based on topographic surveys associated wave climate conditions registered between 2003 and 2008 and typical wave conditions registered over a longer wave climate time period this work compares the calibration of two different shoreline evolution models long term configuration ltc and genesis for this period then considering the 2003 topographic conditions for the models calibration the results of both models are discussed with respect to simulation scenarios after 10 15 and 20 years of evolution the 10 year evolution projections of the models are also compared to the results of a survey performed in february 2012 for the wave data calibration period 2003 2008 the average shoreline retreat of the analysed coastal stretch was reproduced with small differences around 1 and 10 for ltc and 15 and 14 for genesis considering stretches ab or ac respectively though local differences along the ab coastal stretch represent root mean square errors reaching up to 52 and 88 for genesis and ltc respectively and were above 118 for both models along the ac coastal stretch

cyclic changes in the sedimentary environment during the last interglacial glacial cycle coastal jameson land east greenland abstract raised successions of sediments from the last interglacial glacial period along coastal jameson land east greenland comprise a variety of sedimentary facies that reflect cyclic changes of the sedimentary environment these changes are controlled by the fluctuations of relative sea level and glacier advances each of the sedimentary cycles starts with till deposition succeeded by marine mud sedimentation subaerial erosion deltaic and coastal sedimentation sea level changes alters from falling to rising during each sedimentary cycle and indicates that local east greenland glacier fluctuations generally lead the global eustatic cycles most of the deposits cover isotope stage 5 and successive higher sea level stands during each sedimentary cycle indicate a net growth of the greenland ice sheet during the early weichselian

the youngest known dictyodora from the late permian lopingian deep sea in west qinling central china abstract dictyodora has been generally considered an ichnogenus with a restricted temporal range from the cambrian to the mississippian until now there have been no reports of dictyodora after the mississippian here we report on well preserved and abundant dictyodora from deep sea sediments of the lopingian maomaolong formation in west qinling central china which is hitherto the youngest occurrence of dictyodora and extends the stratigraphic range of dictyodora to the late permian two ichnospecies of dictyodora are distinguished d zimmermanni and d cf scotica unlike the small sized dictyodora in the pre pennsylvanian the three dimensional morphology of dictyodora studied here shows larger amplitudes and longer limbs with clearly inclined walls and basal burrows which are interpreted to have been made by a soft bodied worm like organism with a snorkel like organ as similarly documented in previous studies detailed systematic ichnological features and sem and eds results indicate that dictyodora here is not simply a respiration structure made during the locomotion of the trace maker but resulted from active filling by the trace maker dictyodora is probably not a good indicator of the deep marine environment in the paleozoic from our dataset dictyodora originated from the shallow marine environment in the early cambrian then migrated into the deep sea in the ordovician and the marginal marine setting in the wenlock and was finally restricted to the deep marine environment in the carboniferous and permian both psammichnites and dictyodora are structures made by organisms with snorkel like organs and both were eliminated during the end permian mass extinction

organic carbon and sedimentation rate further evidence for anoxic deep water conditions in the cenomanian turonian atlantic ocean abstract the relationship between organic carbon content and sedimentation rate based on data derived from recent to miocene sediments deposited under oxic and anoxic sea water conditions is used to characterize the different depositional environments these data are compared with data of cenomanian turonian dsdp sediments from the atlantic ocean the results may support deposition in anoxic environments due to extremely reduced deep water circulation as the main cause for the formation of cenomanian turonian black shales in the north atlantic rather than increased supply of organic matter due to higher oceanic productivity

age dating and the orbital theory of the ice ages development of a high resolution 0 to 300 000 year chronostratigraphy using the concept of orbital tuning a continuous high resolution deep sea chronostratigraphy has been developed spanning the last 300 000 yr the chronology is developed using a stacked oxygen isotope stratigraphy and four different orbital tuning approaches each of which is based upon a different assumption concerning the response of the orbital signal recorded in the data each approach yields a separate chronology the error measured by the standard deviation about the average of these four results which represents the best chronology has an average magnitude of only 2500 yr this small value indicates that the chronology produced is insensitive to the specific orbital tuning technique used excellent convergence between chronologies developed using each of five different paleoclimatological indicators from a single core is also obtained the resultant chronology is also insensitive to the specific indicator used the error associated with each tuning approach is estimated independently and propagated through to the average result the resulting error estimate is independent of that associated with the degree of convergence and has an average magnitude of 3500 yr in excellent agreement with the 2500 yr estimate transfer of the final chronology to the stacked record leads to an estimated error of 1500 yr thus the final chronology has an average error of 5000 yr

palaeomagnetic excursions recorded in mid weichselian cave sediments from skjonghelleren valderoy w norway abstract anomalous single component palaeomagnetic directions in laminated clay silt sediments in the non karstic skjonghelleren cave w norway are interpreted to record two high resolution but incomplete records of geomagnetic field excursions a depositional non distorted origin of magnetization carried by ultra fine magnetite maghemite grains has been inferred from field evidence redeposition experiments and magnetic fabric properties the sediments deposited sub glacially between 56 ka to 12 ka determined by consistent isotope ages obtained from bones and travertine the youngest excursion

ecologic interpretation of deep sea trace fossil communities abstract trace fossil types and their vertical arrangement tiering are closely related to the biotope and hence can provide information on ecological conditions especially on oxygenation benthic food content sedimentation rate and substrate consistency however to use the full potential of trace fossils for environmental analyses various ichnologic criteria are necessary in addition to trace fossil taxonomy based on a taxonomically oriented ichnologic evaluation of modern deep sea environments six ichnologic aspects to ecologic changes have been found to be of major importance 1 1 penetration depth of burrows is influenced by oxygenation benthic food availability and substrate consistency 2 2 the number and vertical extension of tiers varies due to environmental changes a decrease in the vertical extension of tiers telescoping indicates a decrease in oxygenation benthic food content and or sedimentation rate if shallow penetrating traces disappear oxygen may be depleted and if the deepest tiers disappear the benthic food content may be lowered 3 3 the size diameter of specific trace fossils can indicate oxygen and benthic food availability 4 4 degree of bioturbation is related to sedimentation rate and benthic food content and the diversity of the whole ichnocoenoses or within a specific tier is affected by oxygenation benthic food content sedimentation rate and substrate consistency 5 5 the type of burrow wall unlined mucus lined pellet lined mainly refers to substrate consistency and subordinately to pore water oxygenation 6 6 the type of sediment displacement by body appendages used for excavation ingestion sideward pressing or outside pumping is related to substrate consistency and grain size

beach and dune erosion during storm surges this paper presents the set up and results of an extensive research programme concerning the erosion of coastal dunes during storm surges a large number of two dimensional and three dimensional mobile bed model tests has been carried out to investigate the process of dune erosion the state of art after a series of small scale tests is summarized attention is focussed on large scale tests carried out in the delta flume with random waves up to 2 m significant height sediment concentration and orbital velocity measurements are discussed the large scale tests have confirmed the validity of a modelling technique based on the dimensionless fall velocity parameter h tw the model results are being applied to check the safety of existing coastal dunes as a water retaining structure that has to protect the major part of the netherlands from inundation during storm surges

pyrite framboids interpreted as microbial colonies within the permian zoophycos spreiten from southeastern australia two types of pyrite framboids pf probably sulphate reducing bacteria have been found within the zoophycos spreiten hosted in the guadalupian middle permian glaciomarine greywacke of the westley park sandstone member within the broughton formation from the southern sydney basin of southeastern australia they are composed of non sheathed pf1 and sheathed pf2 sub micron balls respectively chemically the sub micron balls consist of iron sulphur carbon and oxygen both pf1 and pf2 occur in rhythmic alternation within the thick light grey and thin dark grey minor lamellae of zoophycos spreiten the framboids from the minor lamellae are highly abundant and occur in an orderly arrangement of equal density and in a good state of preservation within zoophycos spreiten no homogeneous filling fecal pellets or any sign of re exploitation of the minor lamellae have been recognized no similar framboids have been observed outside zoophycos spreiten therefore the framboids are interpreted as the pyritized remains of microbial colonies within zoophycos spreiten the trace zoophycos would be a multifunctional garden that may have been carefully constructed by the zoophycos maker where different microbial colonies were orderly and carefully planted and cultured within different minor lamellae further it is proposed that the zoophycos maker had a symbiotic relationship with microbial colonies on the mutual basis of food supply and redox conditions the fact that the overlying spreiten cut the underlying ones indicates that the zoophycos from the study area is of an upward construction the rhythmic alternation of both the thick light grey and thin dark grey minor lamellae within zoophycos spreiten may be suggestive of a gardening manner of the zoophycos maker responding to the warm and cold changes food supply in pulses and variations of sedimentation rate for planting and culturing microbial colonies under the conditions of a glaciomarine environment at the high latitudes

trace fossils indicating bottom aeration changes folusz limestone oligocene outer carpathians poland abstract bioturbation sequences in the pelagic folusz limestone indicate deposition under decreasing bottom aeration possibly in association with the development of microbial mats u shaped burrows diplocraterion and arenicolites exclusively were produced in the laminated limestone and they represent the only colonizers sessile suspension feeders of the oxygen deficient sediment

groin impacts on updrift morphology physical and numerical study abstract groins interfere with coastal dynamics and sediment transport leading to sediments accumulation at the updrift side while at downdrift the erosive process is anticipated due to the lack of sediments to improve numerical modeling capacity to simulate the groins impacts it is necessary to totally understand the shoreline evolution along time and its relationship with the cross shore profiles shape the main goal of this work was to analyze and compare the performance of physical and numerical studies on evaluating the evolution of updrift cross shore profiles geometry and shoreline position after the construction of a groin this study analyzed a coastal stretch updrift of the groin at a prototype and model scales considering the analytical formulation of pelnard considere the numerical model ltc long term configuration and the laboratory tests the laboratory tested scenario was designed with the aim to gather results which could be analyzed and compared with numerical simulations from ltc coelho 2005 allowing its improvement and with the pelnard considere 1956 analytical formulation both at model scale the developed study shows an important difference between ltc and pelnard considere 1956 approaches because the analytical solution for the shoreline in equilibrium does not include the wave refraction effects over the updated bathymetry ltc observed trend of the equilibrium shoreline is not parallel to the initial shoreline and this behavior was confirmed in the laboratory tests it was also observed that the sediment transport capacity has very small impact on the ltc shoreline configuration despite the refraction effects over the updated bathymetries along time the profile shape obtained in laboratory includes bed forms difficult to reproduce in long term numerical modeling evaluation of cross shore profiles because ltc transversal behavior is only based on geometrical considerations and does not represent cross shore sediment transport and its impact on profile geometry

sand size versus beachface slope an explanation based on the constructal law article i nfo article history the relationship between beachface slope and sand grain size has been established based on multiple observations of beach characteristics in many parts of the world we show that this observational result may be understood in the light of the constructal law bejan 1997 a model of wave run up and run down along the beachface swash was developed to account for superficial flows together with flows through the porous sand bed of average porosity 0 35 the permeability of which may be related to grain diameter and sphericity 0 9 for sand grains through the kozeny carman equation then by using the constructal law we minimized the time for completing a swash cycle under fixed wave height and sand grain diameter as the result a relationship involving sand grain size beachface slope and open ocean wave height has been obtained and then discussed and validated against experimental data in addition this relationship has also been used to illuminate beachface dynamic processes namely the reshaping of sandy beachfaces in response to changes in wave height though the model used in this work may be improved further the results appear to show as with other natural systems that beachface morphing in time may be understood based on a unifying principle the constructal law

evaluating controls on ice dynamics in the north east atlantic using an event stratigraphy approach abstract an event stratigraphy approach is used to examine controls on late devensian age glacial events in ireland the event stratigraphy based on onshore geological evidence is constructed from relative age relationships of cross cutting bedforms found behind ice margins and radiometric dates from ice marginal landforms the event stratigraphy can be compared with the greenland grip ice core 18o proxy climate record and high resolution marine records in the north east atlantic these records reflect different aspects of the coupled ice ocean atmosphere system on different scales prior to heinrich event 1 at 14 5 14c kyr bp cal 17 kyr bp the glacial event stratigraphy in ireland more closely matches events recorded in north atlantic marine cores after heinrich event 1 the ireland glacial event stratigraphy better fits with the greenland 18o record this shift in phasing relations in the north east atlantic following heinrich event 1 reflects a range of variables including onshore ice retreat changes in sea ice cover and strengthened thermohaline circulation the grip event stratigraphy may therefore not always be the most appropriate standard against which to compare all glacial climate records in the north east atlantic region late devensian glacial events in ireland match better to shifts observed in the marine record suggesting an ocean driver of glacial events in north west europe

reappraisal of the cambrian glauconite bearing anse maranda formation quebec appalachians from deep sea turbidites to clastic shelf deposits the cambrian anse maranda formation is a glauconite bearing clastic succession within the quebec reentrant it is part of the appalachians humber zone particularly of the shale feldspathic sandstone assemblage which represents the rift to drift deposits of the laurentian margin the massive sandstones of the anse maranda were originally interpreted as the proximal turbidites of a deep sea fan the occurrence of glauconite and the high degree of bioturbation which give the sandstones a massive aspect suggest a different depositional environment detailed ichnology and lithofacies descriptions indicate that the anse maranda predominantly represents shelf sediments deposited in storm influenced environment and that intense bioturbation destroyed most of the sedimentary structures the paleo geographic reconstruction suggests that the anse maranda was deposited seaward of a headland identified as the montmorency promontory along a narrow shelf with an irregular topography some coeval turbidites of sim

ichnology of american chalks the selma group upper cretaceous western alabama chalk facies within the selma group most of them impure crop out only in a relatively small area of western alabama and eastern mississippi and grade laterally into calcareous terrigenous clastics body fossils and skeletal borings described in a separate paper are diverse and abundant in some units especially the impure chalks major burrow forms also distributed unequally among these units include chondrites sp cylindrichnus pustulosus n sp planolites beverleyensis skolithos sp teichichnus rectus teichichnus zigzag n sp thalassinoides paradoxicus thalassinoides suevicus trichichnus linearis zoophycos sp and mineralized burrows minor forms include palaeophycus sp rosselia spp and mantled burrows characteristic trace fossil distributions especially include the striking dominance of thalassinoides paradoxicus in chalk hardgrounds of the arcola member of the mooreville chalk and successive patterns of bioturbation in the lower unnamed member of the demopolis chalk in purer chal

global variations of surface ocean productivity in low and mid latitudes influence on co2 reservoirs of the deep ocean and atmosphere during the last 21 000 years based on detailed reconstructions of global distribution patterns both paleoproductivity and the benthic 13c record of co2 which is dissolved in the deep ocean strongly differed between the last glacial maximum and the holocene with the onset of termination i about 15 000 years ago the new export production of low and mid latitude upwelling cells started to decline by more than 2 4 gt carbon year this reduction is regarded as a main factor leading to both the simultaneous rise in atmospheric co2 as recorded in ice cores and with a slight delay of more than 1000 years to a large scale gradual co2 depletion of the deep ocean by about 650 gt c this estimate is based on an average increase in benthic 13c by 0 4 0 5 the decrease in new production also matches a clear 13c depletion of organic matter possibly recording an end of extreme nutrient utilization in upwelling cells as shown by sarnthein et al 1987 the productivity reversal appears to be triggered by a rapid reduction in the strength of meridional trades which in turn was linked via a shrinking extent of sea ice to a massive increase in high latitude insolation i e to orbital forcing as primary cause

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

zoophycos distribution and sequence stratigraphy examples from the jurassic and cretaceous deposits of southeastern france the trace fossil zoophycos is characteristic in certain jurassic and cretaceous basinal deposits of southeastern france these deposits are cyclic marl limestone alternations in which depositional sequences can easily be recognized two kinds of sequence have been studied the marl limestone couplet and the third order sequence detailed observations show that zoophycos has a particular position in the sequences in the marl limestone couplet the trace is concentrated towards the upper part of the calcareous beds the burrow is also present in the lower part of the beds and at the top of the underlying marls but is less abundant the same kind of burrow distribution occurs in the third order sequences zoophycos is concentrated in the upper part of the calcareous bundles which are interpreted as lowstand systems tracts while it is totally lacking in the superimposed more marly sequence which probably corresponds to the lower part of the transgressive systems tracts the burrow may be present throughout the highstand systems tracts which overlie the maximum flooding surfaces but is less abundant the particular distribution of zoophycos is related to the fluctuations of certain environmental factors the most important of which are the carbonate productivity the sedimentation rate and the substrate consistency zoophycos can be proposed as a useful marker of sequence boundaries and of the transgressive surfaces in distal deposits where other signals for sequence analysis are often lacking

quaternary glaciations in southern fennoscandia evidence from southwestern norway and the northern north sea region abstract based on records from the northern north sea and southern norway quaternary fennoscandian glaciations are described and discussed maximum glaciation defined as the presence of shelf edge glaciation an ice stream flowing out of the norwegian channel and most likely an ice divide over the central part of fennoscandia sweden gulf of bothnia occurred for the first time in the late cenozoic at ca 1 1 myr the fedje glaciation this glaciation was followed by a ca 600 kyr period with at least two glaciations with ice extension somewhat larger than the younger dryas event in the region the first maximum glaciation of the bruhnes chron was during isotope stage 12 and was followed by repeated maximum glaciations within each of the light isotopic stages until stage 2 during the weichselian the southwestern part of the fennoscandian ice sheet reached maximum position three times sometime between 22 and 28 37 and 50 and 60 and 80 ka limited glaciations probably occurred during stadials between the early and middle weichselian interstadials between 500 ka and 1 1 myr and most likely also prior to 1 1 myr deep norwegian sea ice rafted detritus ird records reflecting contributions from several different ice sheets fennoscandian barents sea iceland and greenland each with large variations in history of ice extent to their respective margins yet to some degree they reflect the glaciation of the northern north sea region with an increasing ird input around 1 1 myr and a relatively low input of north sea components during some cycles around the b m boundary maximum glaciations occurred during insolation minima in the earlier part of the middle pleistocene however not all such minima are reflected by maximum glaciation in southern parts of fennoscandia the relatively poor chronological control and non continuous character of the data on weichselian interstadials stadials precludes a clear relationship to atmospheric changes recorded in greenland ice cores as well as to precession and or obliquity cycles in insolation

weichselian till stratigraphy and glacial history of finnmarksvidda north norway abstract during the last decade the geological survey of norway has performed surficial and stratigraphical mapping of the quaternary geology in finnmark north norway this mapping has revealed a complex late pleistocene stratigraphy with tills and intercalated gravels and sands which indicate at least three stadials and two interstadials during the weichselian older glacial events are also recognized true in situ organic material from an old ice free period was first found in this area during the 1988 field season preliminary pollen counts of this material indicate interglacial conditions of probable eemian age based on all the available stratigraphic data a model for the late pleistocene glacial history has been developed the locations of the ice accumulation zones during the three recognized stadials were different the first stadial had ice domes in both the mountains and the lower inland area the second stadial was mainly a mountain ice dome glaciation whereas the last stadial or glaciation had mainly inland ice domes the glacial record for northern fennoscandia indicates that glacial expansion during the early and middle weichselian did not reach a size comparable to that of the weichselian maximum ca 20 ka bp

late quaternary calcareous nannofossil biostratigraphy and sedimentation patterns fram strait arctica sediment cores from the fram strait are dated by means of calcareous nannofossil biostratigraphy and are shown to represent at the most the last 300 kyr oxygen isotope stages 1 8 differences in sedimentation rates are mainly controlled by the bottom topography and the intensity of ice rafted deposition sedimentation rates are normally in the order of a few centimeters per kiloyear in the central fram strait but increase to over 10 cm kyr in cores located on the continental slope the highest sediment accumulation rates occurred on the shelf several tens of centimeters per kiloyear

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

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

late quaternary land sea interactions fennoscandia and svalbard the nordic seas abstract glaciation curves from western spitsbergen northern norway and western norway for the entire last interglacial glacial cycle are presented despite uncertainties due to chronology and discontinuous sedimentary records it seems safe to conclude that there were five major weichselian glacier expansions in western norway so far only three expansions have been recorded in western spitsbergen the weichselian maximum occurred during lower to middle weichselian in western spitsbergen as opposed to the upper weichselian maximum extent for the scandinavian ice sheet episodes of intrusion of relatively warm surface water into the norwegian sea correlate with interstadial conditions in western norway the lower weichselian maximum ice extent in western spitsbergen on the other hand probably occurred during a prolonged period of at least seasonally open water conditions far north in the norwegian sea suggesting that this was the major precipitation source the upper weichselian glaciers in spitsbergen probably failed to grow to a comparable size due to lack of precipitation as the entire norwegian sea probably was ice covered year round throughout most of stage 2 these observations suggest that there is a ca 20 ka interval between glaciations in western norway and a ca 40 ka interval in western spitsbergen this may reflect milankovitch cyclicity but both geological and climatological arguments against this supposition

the jaeren area a border zone of the norwegian channel ice stream abstract the coastal lowlands of jaeren southwestern norway have an extensive cover of quaternary sediments lithological biostratigraphical and geochronological investigations of a series of boreholes across jaeren have allowed us to combine earlier and new information on these deposits into a temporal model of quaternary sedimentation the cores show evidence of at least four ice free episodes with marine deposition during mainly arctic conditions the oldest of these is considered to be ca 200 ka old and the youngest one is the sandnes interstadial which is 14 c ams dated to 32 ka bp interbedded between these units are 10 40 m thick units of till with components of marine material these findings together with a re evaluation of distinct morphological features on jaeren as well as earlier provenance studies strongly suggest that jaeren has been a boundary zone between an ice stream following the norwegian channel draining a substantial part of the southern region of the fennoscandian ice sheet and local ice from south western norway through multiple periods of glaciation starting ca 1 1 myr million years ago the norwegian channel ice stream has been the main conduit of erosion products from southern scandinavia to the deep norwegian sea comparison with ice stream profiles from antarctica suggests that the deposition of relatively young marine sediments as high as ca 200 m a s l on jaeren is a result of glacial isostasy rather than regional tectonic movements

biogenic structures in modern slope to deep sea sediments in the sulu sea basin philippines abstract slowly accumulated slope and rise sediments 5 20 cm 1000 yr are totally bioturbated as compared to only 10 30 in rapidly deposited abyssal plain sediments 100 200 cm 1000 yr in contrast to a decrease in degree of bioturbation biogenic trace diversity increases with water depth all ichnocoenoses are clearly influenced by the low oxygen content of the bottom water caused by minimal circulation and restricted water exchange oxygen deficiency and relatively high sedimentation rates have created nutrient rich sediments thus there is no need for optimal fractionation into individual ecological niches and behavioral programs are not highly developed 1 in slope and rise sediments animal traces are associated with biodeformational structures 2 in slope to abyssal plain sediments trace assemblages are dominated by burrows with open tubes for circulation of respiration water 3 in abyssal plain sediments small diameter biogenic traces common in turbidite sequences graphoglyptids e g paleodictyon are absent this may be due to rapid sedimentation leading to inefficiency of graphoglyptid behavior where graphoglyptids are lacking ichnocoenoses are dominated by forms like phycosiphon in slope and rise sediments graphoglyptids may have been destroyed by deeper burrowing organisms

aminostratigraphy of european marine interglacial deposits molluscan fossils collected from shallow water marine sediment across nw europe and nearby arctic regions have been analysed for the extent of isoleucine epimerization dl ratio in indigenous protein residues the dl ratios confirm that essentially all classical eemian sites from nw europe are of the same age and are correlative with the type locality near amersfoort in the netherlands shells from interglacial marine sediment beneath the type weichselian till in poland also correlate with the type eemian site dl ratios in holsteinian marine shells 0 29 are substantially higher than in their eemian counterparts 0 17 late cromerian shells yield even higher ratios 0 46 dl ratios in late glacial shells 0 06 and middle weichselian shells 0 09 permit differentiation from modern 0 01 and last interglacial material based on the position of the matuyama brunhes boundary and the differences in dl ratios the eemian must correlate with isotope substage 5e whereas the holsteinian is most likely substage 7c possibly stage 9 but certainly younger than stage 11 intra saalian warm periods may be terrestrial equivalents of the younger substages of stage 7 extensive pre eemian marine sediments along the sw coast of denmark previously correlated with the holsteinian are shown to be of late cromerian age the underlying till there is the first widespread evidence of a pre elsterian till in nw europe dl ratios in molluscs from last interglacial sites along the arctic coast of the ussr the arctic islands and eastern greenland are substantially lower than in their european counterparts due to their low thermal histories the combined mid and high latitude data are used to develop a predictive model for the expected dl ratio in any of several moderate epimerization rate taxa for last interglacial sites with mean temperatures between 20 and 15 c not all sites could be unambiguously assigned to an established interglacial the fjosanger norway and margareteberg sweden sites previously thought to be eemian yield dl ratios higher than in secure nearby eemian material it is yet unresolved whether these are aberrant sites or if they predate the last interglacial in situ shoreline deposits encountered in borings in sw belgium and in exposures on the belgium coastal plain contain molluscs that yield dl ratios intermediate between secure eemian and late weichselian ratios raising the possibility that a late stage 5 high sea level event attained near modern levels in the southern north sea basin resolution of these uncertainties is the focus of future work

an energetics total load sediment transport model for a plane sloping beach bagnold s energetics based total load sediment transport model for streams is used as a basis for the development of a total load model of time varying sediment transport over a plane sloping bed in both the bedload and suspended load the transport rate vectors are found to be composed of a velocity induced component directed parallel to the instantaneous velocity vector and a gravity induced component directed down slope the model is applied to idealized surfzone conditions leading to estimates of the local longshore and onshore offshore sediment transport rates as well as the equilibrium beach slope as a function of the local wave and current conditions the model is combined with a nonlinear longshore current model and spatially integrated to obtain predictions of the total longshore transport rate as a function of the incident wave conditions the results support the general form of the wave power equation except that the wave power coefficient is no longer constant but is instead a complex function of the incident wave and beach characteristics

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

structure and function of large lobed zoophycos pliocene of rhodes greece abstract in the kolymbia limestone facies upper pliocene of the rhodes formation of rhodes greece a study was made of a large spiral form of zoophycos named herein zoophycos rhodensis in the small bay south of cape vagia two individuals were excavated and dissected while several more were serially sectioned in a vertical plane the upper parts of the zoophycos were missing through modern beach erosion but in one individual the two lowest whorls were almost completely exposed these comprised a skirt like zone of spreite surrounded by a zone of 63 marginal lobes the diameter of the trace fossils was about 1 m vertical sections demonstrated that the spreiten were composed of material advected downward from a higher horizon indicating that the spreite was produced nearly 1 m below the sea floor the skirt like zone of the spreite was constructed of sigmoidal minor lamellae in bundles separated by major lamellae the radiating major lamellae are not replaced by ridges such as is the case in many other lobed spiral zoophycos the marginal tube and to a lesser extent the spreite are mineralised with an oxidised iron mineral probably once pyrite the marginal tube is completely filled with sediment and shows no signs of collapse or compaction this is taken to indicate active backfilling and that the operative burrow was thus j shaped and not u shaped the two zones of the spreite are considered to represent two different modes of behaviour the skirt like zone probably represents deposit feeding the mineralised marginal tube and lobes possibly represent sulphide wells connected with chemosymbiosis between the trace making animal and sulphide oxidising bacteria

characteristic trace fossil associations in oxygen poor sedimentary environments the sedimentologic record of oxygen poor depositional environments typically includes trace fossils produced by deposit feeding organisms we propose an oxygen controlled trace fossil model in which increasing oxygen concentration of interstitial water in sediment parallels a transition from fodinichnia dominated through pascichnia dominated to domichnia dominated trace fossil associations in certain places such as parts of the late paleozoic oquirrh basin in utah this model provides a reasonable alternative to the more traditional depth controlled model of trace fossil distribution

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

trace fossils as indicators of environmental change in holocene sediments of the archipelago sea northern baltic sea abstract biogenic structures in holocene sediments from the archipelago sea northern baltic sea were characterized through the analysis of x ray images of four cores collected from water depths between 32 and 66 m in the area initial colonization of endobenthic invertebrates occurred at 7800 80 calendar years bp the trace assemblage at this level is low diversity small diameter shallowly tiered and palaeophycus dominated rare arenicolites are also observed early colonization coincides with increasing marine influence in the post glacial lacustrine setting just before the dramatic onset of brackish water conditions established after 7600 bp the post incursion brackish water assemblage possesses a higher diversity of traces planolites arenicolites lockeia teichichnus which is taken to reflect the enhanced salinity and trophic state of the basin the shift from palaeophycus mottling to a planolites dominated fabric represents changed behavioural patterns in the endobenthic community due to changed substrate properties the ethology of the succeeding trace assemblage also represents a switch from domicile based activities such as predation scavenging and interface dominated deposit feeding to shallow tier deposit feeding finally traces are excluded from thinly laminated intervals demonstrating that seafloor oxygen deficiency commonly reached levels that were detrimental to colonization of the sediment substrate

vertical open burrows in deep sea sediments 2 m in length previous studies of the mixed layer in deep sea sediments suggest a maximum burrowing depth of about 10 30 cm ref 1 however we now report that two recently obtained cores from the north east atlantic s126 2 and s126 4 display open burrows to a depth of 214 cm within a distal pelagic turbidite an organic lining in one of the burrows indicates a modern origin many of the burrows are less than 0 5 mm across and are only visible on fractured surfaces their effects on sediment mixing are probably minimal but they provide a network of open vertical channels which considerably increases the permeability this is of crucial importance to studies involving pore water movement such as those associated with the radioactive waste disposal project the effect of the burrows changes the calculated permeability from the equivalent of a clay to that of a coarse sand the delicate structure of the burrows may result in their closure during handling thus requiring their effect on pore water fluxes to be studied in situ

the ichnogenus teichichnus seilacher 1955 the ichnotaxonomy of the phanerozoic trace fossil teichichnus seilacher 1955 is revised and its ethology producers and environmental affiliation are re evaluated newly studied material reveals that teichichnus is a sub vertical spreite burrow with an arcuate shape containing stacked laminae and a passively filled terminal causative burrow funnel like extension of the terminal causative burrow and wall ornamentation may occur high variation of burrow morphology is common and has resulted in the erection of 18 ichnospecies of which only four are herein regarded as valid teichichnus rectus t zigzag t patens and t duplex these ichnospecies are characterised by their overall burrow shape spreite morphology and more subordinate occurrence of branching and sculpture as recommended ichnotaxobases combined modes of feeding become evident including deposit and suspension feeding suggesting that teichichnus is a dwelling trace rather than a feeding trace aside from the classical interpretation of polychaetes as producers many features accord with an interpretation of dwelling echiurans and holothurians this interpretation may apply for many post palaeozoic t rectus and t zigzag whereas t duplex and partly t patens are likely produced by arthropods i e trilobites and crustaceans bivalves are also considered for producing teichichnus like traces teichichnus is a marine trace fossil with predominance in shallow marine environments low diversity and high density occurrences of teichichnus characterise marginal marine paralic environments with reduced salinity i e brackish water and oxygen i e dysoxia whereas in shoreface and offshore settings teichichnus occurs in association with many other ichnotaxa and in low density deep marine occurrences of teichichnus are comparably sparse and isolated records may indicate dysoxic bottom conditions

current and future mudflat losses in the southern huanghe delta due to coastal hard structures and shoreline retreat abstract coastal wetlands especially broad mudflats are facing an unprecedented crisis due to combined influence of intensified coastal development activities drastic river sediment reduction and rapid relative sea level rise however it is still a huge challenge to accurately assess the evolution of mudflats for the lack of reliable shoreline indicators on satellite images especially the indicators for shoreline at low tide this study based on instantaneous shoreline positions derived from 430 landsat satellite images during 1983 2019 uses sea level correction and statistical analysis methods to study the evolution of laizhou mudflat and the intertidal mudflat loss in laizhou mudflat was accurately assessed and the effects of multiple factors especially the effects of various coastal hard structures on the evolution of laizhou mudflat were quantitatively estimated for the first time the results show that the intertidal mudflat loss caused by the construction of cofferdams was 98 km2 93 of the total intertidal mudflat loss although the previous intertidal mudflat loss caused by shore parallel structures was less the shore parallel structures will cause great mudflat loss in the future and the broad laizhou mudflat will disappear in 110 years owing to the barrier effect of the widespread shore parallel structures if the current rapid shoreline retreat is not improved the construction of shore normal structures can slow the shoreline retreat of adjacent mudflat but accelerate downstream shoreline retreat as far as coastal protection is concerned the construction of shore normal structures in laizhou mudflat is inadvisable diverting 13 m ton year of huanghe sediment can totally offset the mudflat loss on the upstream of dongying pier however the mudflat located on the downstream of dongying pier is hard to restore owing to the block effect of the shore normal structures to the alongshore transported sediment another option is demolishing the shore parallel structures to recover the landward movement of shoreline avoiding the mudflat loss at the expense of land loss

bar generating cross shore flow mechanisms on a beach random waves normally incident on a dissipative beach induce a variety of cross shore flows such as asymmetric oscillatory flow wave grouping induced long wave flow breaking induced turbulent flow and momentum decay induced undertow these flows are identified analyzed and hindcasted in a set of laboratory experiments with the aim of revealing the role of each of the flow mechanisms in the two dimensional case of bar generation on a beach

short term shoreline changes due to cross shore structures a one line numerical model abstract the proposed numerical model simulates the short term temporal changes in shoreline position due to a structure interrupting the longshore sediment flux the impacts of both the groin type construction and underwater trench of arbitrary orientation relative to the shore are discussed in order to estimate the sediment mass trapped by the structure a submodel of the longshore sediment transport induced by a random wave field is developed the contribution of the surface roller in momentum balance as well as in sediment suspension is included the shoreline changes are computed from the equation deduced from the mass conservation the perturbations in the longshore sediment discharge caused by a structure are assumed to concentrate within some boundary area of which the spatial scale is proportional to the structure s length until the latter is exceeded by the width of the sediment flux it is shown in particular that the total effect of a long trench channel and a pier in its nearshore part results in general shoreline recession except for the vicinity of a pier the model is tested against the laboratory data of baidei et al 1994 and applied to the baidara bay coast kara sea where a pipeline would be designed

neoichnology at lake margins implications for paleo lake systems abstract neoichnological studies provide significant information that can aid in the interpretation of ancient ichnological assemblages here we examine for the first time the pattern in both vertebrate and invertebrate trace distribution and abundance that can be seen in two geographically separate but broadly analogous contemporary semi arid climate lake margin settings in an effort to describe taphonomic processes relevant to paleo lake systems lake margin to supralittoral zone transects were made at ruby reservoir montana usa and la sotonera spain and vegetation cover trace cover trace diversity and substrate characteristics were recorded similar patterns in trace distribution were seen through the eulittoral to supralittoral zones with the majority of traces identified within a single transect present at both sites however a few traces attributed to larger organisms were found to be unique to each and in some instances could to be assigned to a specific trace maker the eulittoral zone was considered to have characteristics attributable to the scoyenia ichnofacies however analysis of the supralittoral zone shows some characteristics of both the coprinisphaera and the mermia ichnofacies in addition a transitional zone between a scoyenia like ichnofacies and a fully terrestrial assemblage was found which may enable continental ichnofacies to be further refined for application to paleo lake systems study of the distribution of traces with distance along the transects also suggests taphonomic biases against the preservation of certain types of traces e g avian due to seasonal fluctuations of the lake level and the subsequent reduced preservation potential for lake proximal traces

trace fossil model for reconstruction of paleo oxygenation in bottom waters recognition of fluctuations in the degree of paleo oxygenation of bottom waters recorded in fine grained pelagic strata is important for interpretation of paleoceanographic and paleoclimatologic conditions general sedimentary fabric composition of trace fossil assemblages and burrow size and crosscutting relationships have been incorporated into a trace fossil tiering model that permits detailed reconstruction of changes in paleo oxygenation of bottom waters applications of this model to the miocene monterey formation california and the cretaceous niobrara formation colorado indicate that the ichnologic approach is more sensitive to both magnitude and rates of change in oxygenation levels compared to macrobenthic body fossil information

marine caves on off signals for glaciations abstract a marine cut cave situated above the highest postglacial sea level in western norway contains a 15 m thick sediment sequence showing a repetitive pattern of glacial and non glacial sediments three periods of continental glaciation with underlying intervening and overlying ice free periods are recorded the glaciogenic sediments consist of laminated silts and clays deposited in an ice dammed lake the ice free periods are represented by blocky beds where the blocks are weathered from the cave ceiling by frost shattering speleothem fragments are found in the upper three of the blocky beds vertebrate bones in the upper two the sediments range in age from ca 80 90 ka to the present the last ice free period the alesund interstadial is dated to around 30 ka bp such repetitive sequences are rare in formerly glaciated regions due to glacial erosion but surveying of several caves in western norway suggests that they might be quite common in caves

sedimentologic significance of turbidite ichnofacies in the saraceno formation eocene southern italy abstract mixed siliciclastic carbonate and siliciclastic turbidites of the saraceno formation eocene in calabria southern italy contain diverse trace fossil associations the depositional setting appears to have been a small tectonically isolated rapidly subsiding borderland basin into which turbidity currents dumped a variety of sediments the formation comprises four sedimentary facies each of which is characterized by a distinctive ichnofacies from bottom to top facies i alternating calcarenite and thick bedded shale chondrites muensteria rhizocorallium facies ii alternating calcarenite and thin bedded shale chondrites muensteria zoophycos facies iii thin bedded siliciclastic sandstone zoophycos helminthoida palaeophycus facies iv alternating sili iclastic sandstone and shale zoophycos helminthoida phycosiphon the trace fossil associations are dominated by fodinichnia such as chondrites in the lower part of the formation facies i and ii and zoophycos in the upper part facies iii and iv the agrichnia graphoglyptids and pascichnia that usually dominate turbidite ichnofacies are uncommon perhaps owing to a a fairly shallow water depth b an extremely high frequency of turbidity currents and or c dysaerobic or anaerobic interstitial conditions within the sediment

coastal sediments and patterns of bioturbation eastern buzzards bay massachusetts abstract coastal sequences of eastern buzzards bay exhibit characteristic suites of physical and biogenic sedimentary structures related to energy gradients geomorphology and distributions of palimpsest glacial debris in beach to offshore sequences unbioturbated planar to ripple laminated or cross bedded pebbly sands of the foreshore and shoreface give way abruptly to thoroughly bioturbated poorly sorted sediments of the offshore zone preserved biogenic sedimentary structures first appear at water depths of 1 to 2 m below mlw and bioturbation of sediments is complete at depths of 2 to 4 m offshore the seaward shift from physical to biogenic structures is a pivotal point almost equally discernible among modern and ancient beach to offshore deposits sequences in harbors and embayments intergrade with those of such allied environments as salt marsh estuaries tidal flats and the offshore zone tidal creek deposits within salt marshes range from sparsely bioturbated cross bedded sand to completely bioturbated impure sand most streamside marsh deposits consist of thoroughly bioturbated root bound muddy sand or sandy mud collectively these bay marsh sequences are reminiscent of albeit at a much smaller scale than estuarine sequences of the georgia bight

quantitative ichnology of modern pelagic deposits in the abyssal atlantic abstract quantitative sedimentologic aspects of bioturbation were investigated in a series of deep sea box cores which were collected over a broad latitudinal range 35 n to 30 s and bathymetric range 1 4 to 5 7 km in the central atlantic ocean all cores were thoroughly bioturbated and numerous generations of burrowing could be discerned in many instances preservation of individually distinct burrows ranged from poor to excellent and eight ichnogenera plus several unnamed biogenic structures were recognized the distribution of calcium carbonate organic carbon selected species of planktic foraminifera and sediment grain size were examined in several cores these measurements indicated that the surficial mixed layer which ranged from 3 to 10 cm thick was statistically more homogeneous than the underlying transition layer this relationship is seen most clearly with respect to lateral and vertical variations in the calcium carbonate content of the cores bioturbation of abyssal pelagic deposits appears to be a two phase process consisting of a homogenization of the upper few centimeters i e the mixed layer by shallow burrowing meiofauna and b heterogeneous mixing of the underlying strata i e the transition layer by relatively deep burrowers the heterogeneously mixed transition layer becomes the preserved trace fossil record under normal circumstances the homogenized mixed layer is not preserved

deterministic coastal morphological and sediment transport modeling a review and discussion 1 modern coastal ocean modeling systems are now capable of numerically simulating a variety of coastal and estuarine problems and can thus provide useful information for managing coastal zones here we review state of the art eulerian implementations of bottom up sediment transport and morphological change in coastal ocean hydrodynamic models in order to investigate the fate of suspended sediment in coastal and estuarine waters as well as the evolution of sea or river beds sediment dynamics need to be represented at a scale relevant to the numerical discretized solution and significant effort is devoted to parameterize sediment processes we discuss boundary layer hydrodynamics and the computation of the bed shear stress we also focus on approaches used to represent near bed processes such as bed load transport and sediment erosion and deposition sediment diffusivities settling velocities and cohesive processes such as flocculation all have an impact on suspended sediment throughout the water column we then describe the implementation of process parameterizations in coastal hydrodynamic models explicitly reviewing five widely used systems the approaches implemented in these coastal models may present distinct strengths and shortcomings with regard to some important issues for coastal zones both numerical and physical while these detailed limitations need to be considered as part of model assessment more general issues also hinder present state of the art models in particular sediment transport is inherently highly empirical which is further compounded by issues arising from turbulence closure schemes we conclude by suggesting some possible directions toward improving sediment dynamics understanding and coastal scale predictive ability

morphodynamics of structurally controlled headland bay beaches in southeastern brazil a review abstract this paper presents a comprehensive review on the interaction between hydrodynamic processes beach morphology and sedimentology at large scale coastal behaviour along the coastline of santa catarina between laguna and sao francisco island a microtidal east coast swell environment with headland and bay geomorphologies the parabolic bay shape equation has proven to be a convenient and practical tool for studying the stability of the headland bay beaches tombolos and salients in santa catarina the beaches exhibit different patterns of sediment removal as a function of the degree of beach curvature in highly curved beaches there is a well developed shadow zone and a range of morphodynamic conditions from a sheltered low energy beach adjacent to the downdrift headland to a high energy exposed beach on the straight end of the headland bay beach the less curved beaches instead tend to show more uniform behaviour since they are directly exposed to incident waves there is no obvious relationship between average wave height and mean grain size showing the importance of sediment source to characterize the sedimentary distribution patterns in the study area the analysis of beaches showed that beach morphodynamics and sequence profiles for a bay headland coast in a microtidal east coast environment is a function of geological inheritance e g distance between headlands and orientation nearshore and inner shelf morphology coastal plain morphology and sediment source and hydrodynamic factors wave conditions oceanic wave exposure and relative tidal range

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

stratigraphic completeness tiered trace fossils provide a measuring stick trace fossil associations commonly display a characteristic vertical zonation tiering within the substrate when burrows of a particular tier become truncated by turbidites tempestites or other results of catastrophic events they provide a simple but quantitative caliper for estimating stratigraphic incompleteness the minimum amount of penecontemporaneous sea floor erosion can be determined by types and sequences of trace fossils preserved below event deposits

sand waves echinocardium traces and their bathyal depositional setting monte torre palaeostrait plio pleistocene southern italy stacked cross sets up to 2 5 m thick produced by sand wave migration and meniscate trace fossils produced by echinocardium cordatum both considered in the literature as typical of shallow water marine depositional settings commonly occur in the bathyal plio pleistocene deposits of monte torre calabria southern italy the plio pleistocene sediments form two coarsening upward depositional sequences separated by an unconformity and by a palaeobathymetric gap of at least 300 m the lower sequence passes upwards from hemipelagic marls and thin bedded turbidites to thick bedded sandy turbidites then to sand wave deposits alternated with sandy turbidites and finally to base of slope megabreccias facies characteristics and relationships and the occurrence of deep sea faunal associations indicate deposition in the bathyal zone the facies of the upper sequence reflect a fan delta environment no deeper than a few tens of metres the depositional setting of the lower sequence where the sand wave deposits and meniscate trace fossils occur appears to have been a tectonically controlled seaway connecting the tyrrhenian and ionian seas this seaway became progressively narrower with time evolving into a strait the overall coarsening upward trend reflects the upward transition from a low to a high energy environment possibly caused by the tectonic narrowing of the seaway deposition and erosion from high concentration turbidity currents and from tidal bottom currents were important processes periods of tectonic activity producing first the uplift of the seaway margins and culminating with the uplift of the strait sequence itself are marked by scattered rockfall deposits the strait setting causing the development of powerful oxygenated bottom currents produced optimal conditions in the bathyal zone for the colonization of sandy bottoms by a single infaunal r selected species echinocardium sp

eustatic signals in deep marine sedimentary sequences recovered at odp site 978 alboran basin western mediterranean sea abstract a continuous section of pliocene marine sediments was recovered at ocean drilling program site 978 located in the alboran sea between spain and morocco three pliocene subunits have been defined at site 978 the lowermost subunit ic 129 2 m thick is characterized by alternating beds of lighter more calcareous and darker less calcareous claystone with bioturbated upper and lower contacts type 1 cycles the middle subunit ib 67 1 m thick is composed of relatively homogeneous nannofossil claystone and the uppermost subunit ia 211 6 m thick contains abrupt based darker terrigenous layers interpreted as turbidites that are interstratified with lighter nannofossil claystone type 2 cycles the rhythmically bedded light and dark layers in subunit ic correlate with those in the rosello composite section of sicily a global reference standard for the pliocene time scale these sedimentary cycles are products of variations in precession and resulting continental runoff missing cycles occur during eustatic highstands the shift to more homogeneous sedimentation in subunit ib is represented in similar aged sequences throughout the mediterranean which display evidence of submarine mass wasting mediterranean wide slope degradation was likely a response to rapid sea level change at approximately 3 ma this change in sedimentation style was accompanied by an upsection increase in sediment accumulation rates associated with turbidite influx in subunit ia turbidite frequency throughout the pliocene section can be linked to eustatic changes in sea level with turbidite maxima corresponding with mid sequence downlap surfaces and their associated condensed sections

the last glaciation of germania land and adjacent areas northeast greenland a profile across the unglaciated coast of northeast greenland at 77 n was studied with regard to the quaternary stratigraphy and glacial history the germania land peninsula is characterised by till covered lower ground which contrasts sharply with the blockfields and extensive gelifluction deposits of its higher altitudes two glaciations are distinguished the older one extended over the entire area and had its margin on the continental shelf the younger one of late weichselian age reached the present coastline and several mountains and high plateaus on western germania land formed nunataks the late weichselian glaciation was more extensive and occurred later on the germania land peninsula than on the coast further south radiocarbon dates suggest that the glacier margin rested to the east of the present coastline until ca 10 000 yr bp this correlates with the late weichselian milne land stage which is found as a late glacial readvance along the coast of east greenland a series of recessional moraines formed during the deglaciation were probably caused by glacier dynamics as opposed to being of climatic origin

the last interglacial glacial period on spitsbergen svalbard the glaciation history of svalbard 78 n and the nw barents sea is reconstructed for the last 130 ka based on studies of sediments exposed in coastal cliffs at the head of isfjorden four different till beds separated by marine sediments are recognized the lowest marine formation containing mytilus edulis reflects warmer conditions than at present and is correlated with the last interglacial the eemian of europe and oxygen isotope substage 5e in the deep sea the post eemian tills are inferred to represent major glaciations around 110 ka bp 75 50 ka bp and 25 10 ka bp during the intervening intervals the glaciers on svalbard were not significantly larger than at present and the nw barents sea was probably ice free the ice free periods named phantomodden and kapp ekholm interstadials lasted from about 110 to 75 and from 50 to 25 ka bp respectively the marine fauna from both these interstadials indicate seasonally ice free conditions the ages of the recorded glaciations coincide with or are slightly younger than periods with insolation minima which at this latitude is determined by a low tilt of the earth s axis thus we postulate that the quaternary glaciations of svalbard were driven by orbital variations with the 41 ka tilt period in contrast to the lower latitude glaciations of scandinavia that were partly driven by the precession cycle with a periodicity of around 23 ka