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

early cambrian wave formed shoreline deposits the hardeberga formation bornholm denmark during the early cambrian the danish island bornholm was situated on the northern edge of the continent baltica with palaeolatitudes of about 35 s an early cambrian terreneuvian transgression inundated large areas of baltica including bornholm creating shallow marine and coastline environments during this period wave formed shoreline sediments the vik member hardeberga formation were deposited on bornholm and are presently exposed at stroby quarry the sediments consist of fine and medium grained quartz cemented arenites in association with a few silt rich mudstones the presence of well preserved subaqueous dunes and wave ripples indicates deposition in a wave dominated upper shoreface littoral zone environment and the presence of interference ripples indicates that the littoral zone environment experienced water level fluctuations due to tides and or changing meteorological conditions discoidal structures medusoids are present in the quarry but due to the relative poor preservation of their fine scale structures it is difficult to determine if the discoids represent true medusae imprints or inorganic structures the preservation of the shallow water bedforms as well as the possible medusae imprints is related to either the formation of thin mud layers formed during a period of calm water when winds blew offshore for a longer period or to the growth of bacterial mats the orientation of the wave formed bedforms indicates a local palaeoshoreline trending ne sw and facing a large ocean to the north

an early lutetian carbon cycle perturbation insights from the gorrondatxe section western pyrenees bay of biscay turbidites and kaolinite a 3 decline in the bulk d 13 c record a 1 decline in benthic foraminiferal d 13 c followed by a gradual recovery a distinct deterioration in foraminiferal preservation high proportions of warm water planktic foraminifera and opportunistic benthic foraminifera and reduced trace fossil and benthic foraminiferal diversity thus recording a significant environmental perturbation the onset of the perturbation correlates with the c21r h6 event recently defined in the atlantic and pacific oceans which caused a 2c warming of the seafloor and increased carbonate dissolution the perturbation was likely caused by the input of 13 c depleted carbon into the ocean atmosphere system thus presenting many of the hallmarks of paleogene hyperthermal deposits however from the available data it is not possible to conclusively state that the event was associated with extreme global warming based on our analysis the perturbation lasted 226 kyr from 47 44 to 47 214 ma and although this duration suggests that the triggering mechanism may have been similar to that of the paleocene eocene thermal maximum petm the magnitude of the carbon input and the subsequent environmental perturbation during the early lutetian event were not as severe as in the petm

climate instability during the last interglacial period recorded in the grip ice core isotope and chemical analyses of the grip ice core from summit central greenland reveal that climate in greenland during the last interglacial period was characterized by a series of severe cold periods which began extremely rapidly and lasted from decades to centuries as the last interglacial seems to have been slightly warmer than the present one its unstable climate raises questions about the effects of future global warming

sea level dynamics and palaeoecological factors affecting trace fossil distribution in eocene turbiditic deposits gorrondatxe section n spain abstract ichnological analysis of the upper ypresian lower lutetian interval at the gorrondatxe section w pyrenees n spain reveals a relationship between sea level dynamics and the eco sedimentary factors influencing trace fossil assemblages the 600 m thick section of deep sea turbiditic deposits contains 41 ichnospecies belonging to 28 ichnogenera which are typical of the nereites ichnofacies and mostly of the paleodictyon ichnosubfacies suggesting deposition in a basin plain to fan fringe setting the trace fossil diversity and abundance fluctuate irrespective of turbidite frequency these ichnological features are strongly affected by trophic level changes related partly to sea level dynamics according to the sequence stratigraphic interpretations for the studied section temperature oxygenation and substrate changes are also considered as relevant factors increased ichnodiversity particularly among graphoglyptids coincides with moderate oligotrophy and stable ecological conditions eutrophisation lowered oxygenation and drop of temperature typical of low sea level can reduce ichnodiversity

covarying sedimentary and biotic fluctuations in lower middle eocene pyrenean deep sea deposits palaeoenvironmental implications abstract analyses of expanded 1975 to 3330 m thick deep marine ypresian lutetian successions from the pamplona and basque basins w pyrenees demonstrate a recurring pattern of coeval sedimentary and biotic changes intervals rich in resedimented deposits are typified by high latitude planktonic foraminiferal indices whereas intervals devoid of large scale resedimented deposits megabreccias are characterized by low latitude planktonic foraminiferal indices data from the megabreccia free intervals record a reasonably good correlation between the vertical trend of planktonic foraminiferal indices from the two pyrenean basins and the global curve of oxygen isotopes from deep sea records for instance the early eocene climatic optimum and the long lasting late ypresian lutetian cooling are respectively recorded in the studied successions by an increase and by a progressive decline in abundance in low latitude planktonic foraminiferal indices this correlation may support the assumption that changes of planktonic foraminiferal indices in the megabreccia free intervals were forced by global climatic changes the dominance of high latitude planktonic foraminiferal indices in the megabreccia bearing intervals is more difficult to interpret such dominance might record global cooling episodes that resulted in eustatic lowstand resedimentation events however the climatic cooling and sea level fall do not fully explain the characteristics of these intervals a reasonable scenario is that tectonically induced resedimentation processes resuspended large volumes of mud and organic matter which led to the eutrophication of seawater such eutrophication would preferentially affect low latitude oligotrophic planktonic foraminiferal species and lead to a relative or absolute increase in the cosmopolitan opportunistic species that typify high latitude groups

multiple early eocene benthic foraminiferal assemblage and δ13c fluctuations at dsdp site 401 bay of biscay ne atlantic abstract within the last decade several early eocene hyperthermals have been detected globally these transient warming events have mainly been characterized geochemically using stable isotopes carbonate content measurements or xrf core scanning yet detailed micropaleontological records are sparse limiting our understanding of the driving forces behind hyperthermals and of the contemporaneous paleoceanography here detailed geochemical and quantitative benthic foraminiferal records are presented from lower eocene pelagic sediments of deep sea drilling project site 401 bay of biscay northeast atlantic in calcareous nannofossil zone np11 several clay enriched levels correspond to negative 13c and 18o bulk rock excursions with amplitudes of up to 0 75 suggesting that significant injections of 12c enriched greenhouse gasses and small temperature rises took place coeval with several of these hyperthermal events the benthic foraminiferal record reveals increased relative abundances of oligotrophic taxa e g nuttallides umbonifera and a reduction in the abundance of buliminid species followed by an increase of opportunistic taxa e g globocassidulina subglobosa and gyroidinoides spp these short lived faunal perturbations are thought to be caused by reduced seasonality of productivity resulting in a decreased corg flux to the seafloor moreover the sedimentological record suggests that an enhanced influx of terrigenous material occurred during these events additionally the most intense 13c decline here called level gives rise to a small yet pronounced long term shift in the benthic foraminiferal composition at this site possibly due to the reappraisal of upwelling and the intensification of bottom water currents these observations imply that environmental changes during smaller hyperthermal events are also reflected in the composition of deep sea benthic communities on both short

the last eocene hyperthermal chron c19r event 41 5 ma chronological and paleoenvironmental insights from a continental margin cape oyambre n spain abstract the last hyperthermal event in the eocene the late lutetian thermal maximum or chron c19r event took place at 41 5 ma during a long term global cooling phase which occurred between the warm early eocene climatic optimum and the icehouse oligocene epoch this paleoclimatic event was first identified in the equatorial atlantic ocean drilling program odp site 1260 as an abrupt peak in bulk fe content and a short lived decline in stable isotopes 13c 18o and carbonate content additional studies have recently been carried from the southern atlantic odp sites 702 and 1263 however many issues were not addressed at these deep sea sites and no land based record of the event had been studied therefore the beach cliff at cape oyambre n spain was analyzed with the aim of identifying the c19r event and investigating its paleoenvironmental impact using magnetostratigraphic and biostratigraphic information the astronomically tuned cyclo stratigraphic record from oyambre was accurately correlated with odp site 1260 this combined with stable isotope data allowed identification of the event in a conspicuous dark marl bed given that the associated negative carbon isotope excursion extends for 2 3 of a precession driven hemicouplet a 7 11 kyr duration was estimated which agrees with recent estimates from the atlantic deep sea sites exceptional insolation conditions were found to have accelerated the hydrological cycle increasing rainfall and runoff on land and terrestrial sediment input to the sea which resulted in relatively low carbonate content in the deep sea sediments the terrestrial input also caused seawater eutrophication and freshening leading to low 13c and 18o values increased abundance of autochthonous and reworked calcareous nannofossil taxa peaks in the abundance of opportunistic reticulofenestra

ichnology and paleoecology of offshore siliciclastic deposits in the cardium formation turonian alberta canada the raven river member of the cardium formation upper cretaceous turonian was deposited in a storm dominated offshore setting in the western interior seaway of north america the ichnology of this unit can provide a useful model for further investigation of shelfal deposits a two fold approach to the ichnology has been utilized in this study first lithofacies are delineated which encompass the degree of bioturbation as part of the rock s sedimentary texture in addition ichnofossil assemblages are established which represent recurring groups of ichnogenera lithofacies comprise several coarsening upward sequences of sandstone and mudstone in which bioturbation tends to decrease upwards mudstone units represent deposition below fairweather wave base in a quiet water setting while sandstone beds are the result of storm generated deposition the sequence shows a punctuated aggradation of shelfal sediments in a storm dominated environment ichnofossil assemblages show a differentiation into pre and post storm ichnogenera with textural changes playing a minor role in assembly composition ichnogenera present include asterosoma bergaueria conichnus cylindrichnus chondrites helminthopsis ophiomorpha palaeophycus planolites rhizocorallium rosselia skolithos teichichnus thalassinoides terebellina and zoophycos

paleoceanographic significance of deep sea benthic foraminiferal species diversity at southeastern indian ocean hole 752a during the neogene abstract diversity parameters of neogene deep sea benthic foraminifera were measured at ocean drilling program odp hole 752a southeastern indian ocean water depth of 1086 3 m using information function h equitability e number of species s and sander s rarefaction values these parameters combined with population abundance of dominant benthic foraminifera bulimina macilenta nuttallides umbonifera cibicides wuellerstorfi cibicides lobatulus bolivina pusilla ehrenbergina carinata gavelinopsis lobatulus cassidulina laevigata globocassiulina subglobosa reveal significant paleoceanographic changes in the southeastern indian ocean during the neogene the values of all the diversity parameters show a decrease from 25 to 23 ma and thereafter an increase with peak values at 13 5 ma the late oligocene to earliest miocene was an interval of more unstable conditions at hole 752a dominated by species characteristic of low organic carbon well ventilated carbonate corrosive high energy conditions the highest values of diversity parameters coincide with the early middle miocene climatic optimum all these parameters show a declining trend and gradual decrease from 13 5 to 4 5 ma coinciding with the major build up of ice sheets in the antarctic region major increase in b pusilla and e carinata population during this time suggests high nutrient levels and low oxygen conditions at hole 752a this interval corresponds with the so called biogenic bloom and an intense oxygen minimum zone as observed throughout the indo pacific region deep waters were warmer from 4 5 to 3 ma marked by an increase in species diversity values coinciding with the early middle pliocene warmth the species diversity values abruptly decreased in the younger interval contemporaneous with the major northern hemisphere glaciation during this time species characteristics of high energy bottom currents and relatively cold deep water were dominant

the upper ypresian and lutetian in san pelegrin section southwestern pyrenean basin magnetostratigraphy and larger foraminifera correlation abstract the current available s hallow benthic zones sbzs calibration based on larger foraminifera is now being improved for the paleogene period in this work the san pelegrin section in the external sierras shows new magnetostratigraphic and biostratigraphic information from the southwestern pyrenean basin where the larger thickness of the shallow marine platforms were developed this environment represents the appropriate frame to calibrate the sbz scale moreover the magnetostratigraphic data can be correlated with biostratigraphic data obtained directly at the same section avoiding limitations of previous correlations the san pelegrin section presents 530 m of ypresian and lutetian rocks 169 sampled levels for magnetostratigraphic purposes have been studied a fact that guarantees the independence and resolution of this record thermal and alternating field demagnetizations were carried out to unravel the characteristic remanent magnetization and the orthogonal diagrams show stable normal and reverse polarity directions three pairs of magnetozones were found along the section enabling to define a robust and reliable local polarity sequence correlated with chrons c23 c22 c21n and c20r the biostratigraphic study distinguished three shallow benthic zones from sbz11 to sbz13 the combination of magneto and biochronologic scales is very useful to improve and to accurate the available shallow benthic zone calibration for this time gap especially for the sbz11 zone now the base of sbz11 can be located at least in 50 96 my because the association is still present at the top of c23n this data is older than previously thought from existent scales on the other side the sbz11 top falls within chron c22n the occurrence of a sedimentary hiatus between c22n and c21n prevents an accurate calibration of the sbz12 top but our profile proves the relation of sbz12 with c22n as well finally the sbz13 zone falls within the limits of recent recalibrations c21n to c20r

growth of an intermittent ice sheet in iceland during the late pliocene and early pleistocene abstract deep sea paleoclimatic records show that the quaternary climate around iceland was and probably still is very sensitive to rapid shifts in north atlantic oceanic circulation studies of several key sections in iceland indicate that similar oscillations are reflected in the late pliocene and early pleistocene terrestrial stratigraphy correlations between six rock sequences in western northern eastern and southern iceland show a fairly distinct trend during the pliocene pleistocene transition indicating the progressive growth of an ice sheet from southeast toward the north and west the correlations are based on k ar dates and paleomagnetic studies a total of 11 glacial horizons are recorded in a stratigraphic column from eastern iceland extending back 6 5 myr in western iceland 7 glacial horizons are preserved in a rock section dated from 7 0 to 1 8 myr and in northern iceland 14 glacial horizons are identified in a section that extends back to 9 0 myr well over 20 glacial horizons have been identified in the stratigraphic column in iceland full scale glacial interglacial cyclicity with regional ice cover is indicated at approximately 2 6 myr a further amplification leading to islandwide glaciations is identified at 2 2 2 1 myr these results show that changes in the ice cover in iceland correlate with the deep sea oxygen isotope records from benthic and planktonic foraminifera as well as ird studies from the north atlantic

an early pleistocene glacial interglacial cycle in the breida vik group on tjornes iceland sedimentary facies foraminifera and molluscs abstract sedimentary facies foraminifera and molluscs are used to reconstruct environmental conditions during the accumulation of the 1 5 ma svarthamar member unit from the tjornes sequence north iceland the tjornes sequence and the breidavik group in particular contains a unique record of cainozoic glacier variations in the north atlantic this is reflected in lithological variations where marine and terrestrial sediments are intercalated between lava flows and pyroclastic rocks on tjornes peninsula our results from the svarthamar member show that the lithological cycle from glacial to proglacial and then to shallow marine sedimentation coincide with faunal succession reflecting a change from arctic to boreal arctic or even boreal conditions in the sea around iceland just after the olduvai event of the matuyama the amplitude of this climatic cycle is comparable to the late pleistocene glacial interglacial cycles in the north atlantic this indicates that the north atlantic current crossed the greenland iceland and iceland faroe ridges during interglacial periods resulting in a periodic northward shift of the polar front during at least a part of the early pleistocene

abrupt increase in greenland snow accumulation at the end of the younger dryas event the warming at the end of the last glaciation was characterized by a series of abrupt returns to glacial climate the best known of which is the younger dryas event1 despite much study of the causes of this event and the mechanisms by which it ended many questions remain unresolved1 oxygen isotope data from greenland ice cores2 4 suggest that the younger dryas ended abruptly over a period of about 50 years dust concentrations2 4 in these cores show an even more rapid transition 20 years this extremely short timescale places severe constraints on the mechanisms underlying the transition but dust concentrations can reflect subtle changes in atmospheric circulation which need not be associated with a large change in climate here we present results from a new greenland ice core gisp2 showing that snow accumulation doubled rapidly from the younger dryas event to the subsequent preboreal interval possibly in one to three years we also find that the accumulation rate change from the oldest dryas to the bo11ing allerod warm period was large and abrupt the extreme rapidity of these changes in a variable that directly represents regional climate implies that the events at the end of the last glaciation may have been responses to some kind of threshold or trigger in the north atlantic climate system

benthic foraminifera in the nazare canyon portuguese continental margin sedimentary environments and disturbance abstract living rose bengal stained benthic foraminifera were investigated from thirteen stations ranging from 146 4976 m water depth in the nazare canyon located on the western iberian continental margin the total standing stocks tss species assemblages and in sediment distributions are compared between stations located on the highly disturbed axis of the upper 4000 m in addition the community changes were investigated in relation to water depth and bio available organic carbon overall low total standing stocks of foraminifera were found in the disturbed canyon axis which experiences frequent sediment resuspension and gravity flows at the upper canyon axis station at 1118 m a rather exceptional fauna was recovered dominated by a species of technitella that made up 75 of the tss the highest tsss were recorded in the upper canyon terrace stations where fine grained sediment and organic carbon are able to accumulate standing stocks on the terraces decreased with increasing water depths the quiescent terrace stations recorded high abundances of infaunal species including melonis barleeanum globobulimina spp and chilostomella oolina the occurrence of these species reflects the low pore water oxygen concentrations and high bio available carbon supply several tubular bathysiphon species were found in the upper canyon terrace stations instead the deepest stations of the lower canyon were dominated by another large agglutinated protozoan saccorhiza ramosa the change in the arborescent tubular foraminiferal community may reflect the increase in sediment oxygenation with increasing water depth in the canyon bathysiphon spp occurring in sediments with higher bio available carbon flux and s ramosa inhabiting more oligotrophic areas

benthic foraminiferal turnover across the cretaceous paleogene boundary at agost southeastern spain paleoenvironmental inferences abstract we studied upper cretaceous and lower paleogene benthic foraminifera from the agost section southeastern spain to infer paleobathymetrical changes and paleoenvironmental turnover across the cretaceous paleogene k p transition benthic foraminifera indicate uppermost bathyal depths at agost during the abathomphalus mayaroensis biochron from about 400 kyr before the k p boundary through the early plummerita hantkeninoides biochron about 120 150 kyr before that boundary the depth increased to middle bathyal for the remainder of the cretaceous and remained so for the danian part of the studied section parasubbotina pseudobulloides biochron at least 200 kyr after the k p boundary there were no perceivable bathymetrical changes at the k p boundary where 5 of the species became extinct and the species composition of the benthic foraminiferal fauna changed considerably below the boundary infaunal morphogroups constitute up to 65 73 of the faunas directly above the boundary in the black clays of the lower guembelitria cretacea biozone benthic foraminifera are rare several opportunistic taxa e g the agglutinant haplophragmoides sp have short peaks in relative abundance possibly reflecting low oxygen conditions as well as environmental instability with benthos receiving food from short lived local blooms of primary producers above the clays through the end of the studied interval epifaunal morphogroups dominate up to 70 of the assemblages or there is an even mixture or epifaunal and infaunal morphogroups infaunal groups do not recover to pre extinction relative abundances indicating that the food supply to the benthos did not recover fully over the studied interval about 200 kyr after the k p boundary the benthic foraminiferal faunal changes are compatible with the direct and indirect effects of an asteroid impact which severely destabilized primary producers and the oceanic food web that was dependent upon them

recent benthic foraminifera from the continental margin of northwest africa community structure and distribution abstract sediment grab samples were collected at 107 locations along the continental margin of northwest africa these samples form a series of depth transects between the straits of gibraltar and dakar senegal the greater than 250 m size fraction was retained for a census of both the live and dead foraminifera after deleting trace occurrences jaccard and correlation coefficient based cluster analyses were performed to decipher the community structure for this margin the geographic distribution of the four major faunal provinces recognized is conventional in that for both the live and dead assemblages three are related to depth upper slope and shelf middle slope and lower slope and continental rise the biotopes and thanatotopes within these provinces are strongly restricted along vertical or latitudinal boundaries when the data are analysed using jaccard coefficients dendrograms constructed from correlation coefficients emphasize depth related faunal communities dominant species such as cibicides lobatulus trifarina fornasinii planulina ariminensis uvigerina finisterrensis and c wuellerstorfi are generally distributed within a definite depth range along this margin and strongly influence the correlation coefficient based dendrograms other distributions are clearly not depth related but correspond to various environmental variables for example cancris auriculus coarse substrate bolivina subaenariensis oxygen minimum cibicidoides kullenbergi and hoeglundina elegans low organic carbon uvigerina peregrina is also a notable exception to depth dependence in that this dominant species and the province it represents are generally confined to the continental slope south of cape blanc its preference for that region may arise from the high organic carbon and fine grain size of the sediment there from low salinity of the bottom water or from other unknown variables the most important vertical faunal boundary occurs between cape barbas and cape blanc between 22 and 21 n latitude in contrast the canary island ridge intersects the continental margin at a saddle depth of about 1500 m but that physiographic barrier has little effect on provincialism of the deep water benthic foraminifera

early cambrian teichichnus dominated ichnofabrics and palaeoenvironmental analysis of the caerfai group southwest wales uk abstract the early cambrian caerfai group of pembrokeshire in southwest wales yields an intensely bioturbated teichichnus dominated ichnofabric and provides evidence for the early evolution of infaunal organisms three units of the caerfai group comprise the focus of this study in sections exposed at caerfai bay in the st non s sandstone few primary sedimentary structures are observed bedding being predominantly massive with subordinate parallel and current ripple cross lamination the topmost st non s sandstone contains common soft sediment deformation phenomena and collectively deposition is believed to have taken place in the proximal subaqueous reaches of a steep fronted delta system teichichnus is the dominant trace with subordinate planolites palaeophycus and possible rhizocorallium the overlying caerfai bay shales were deposited from mass flows with evidence of downslope creep suggesting deposition on a steep delta front sandstone debrites are common as are tuffaceous beds with evidence of reworking by bottom currents sandstone and tuff event beds contain common skolithos and arenicolites with less frequent planolites interbedded mudstones contain infrequent teichichnus the caerfai bay shales coarsen and thicken upwards into the caerbwdy sandstone debrite sandstone beds dominate and bed thickening upsection indicates progradation of the delta system the dominant trace fossil within the unit is teichichnus which is constrained to the top few centimetres of individual sandstone beds less common are planolites and palaeophycus the size and abundance of teichichnus in the caerfai group are similar to or exceed those in contemporaneous sections in avalonia and baltica local environmental factors were probably the primary control on trace fossil distribution substrate and salinity are proposed as the main influences on ichnodiversity and size in the caerfai group teichichnus is most abundant in the st non s sandstone where the proximal reaches of the delta experienced reduced salinity and possibly higher oxygen levels burrow diameter progressively decreases upsection and bioturbation becomes less pervasive in subsequent units of the caerfai group this indicates that by the cambrian stage 2 significant advances into reduced salinity environments had occurred along with the dispersal of the teichichnus producer throughout the avalonia baltica seaway correlation within avalonia indicates that a transgression in the cambrian stage 2 initiated the deposition of the caerfai group marking the onset of the welsh basin

sedimentary labile organic carbon and pore water redox control on species distribution of benthic foraminifera a case study from lisbon setubal canyon southern portugal abstract rose bengal stained benthic foraminifera were studied from 11 cores collected along two depth transects off southern portugal one in the lisbon setubal canyon and the other along the canyon edge the total standing stocks and distribution of foraminifera were investigated in relation to sediment and pore water geochemistry nitrate was used as a redox indicator sedimentary chlorophyll a and cpe chloroplastic pigment equivalents contents as a measure of labile organic matter and total organic carbon as a measure of bulk organic matter availability the canyon sediments were enriched in organic carbon and phytopigments at all water depths in comparison with the canyon edge water depth seemed to control sedimentary phytopigment content but not total organic carbon no significant correlation was seen between pigment and total organic carbon content the abundance of calcareous foraminifera correlated with the phytodetritus content whereas a weaker correlation was observed for the agglutinated taxa therefore calcareous foraminifera appear to require a fresher food input than agglutinated taxa the foraminiferal species composition also varied with pigment content and nitrate penetration depth in the sediment in line with the trox concept phytopigment rich surficial cpe content 20 g cm3 sediments with a shallow nitrate penetration depth 1 cm depth were inhabited by generally infaunal species such as chilostomella oolina melonis barleeanus and globobulimina spp as the nitrate penetration increased to 2 cm depth in sediment and the pigment content remained relatively high 15 g cm3 uvigerina mediterranea and uvigerina elongatastriata became dominant species with declining cpe content and increasing nitrate penetration depth the foraminiferal assemblages changed from the mesotrophic cibicides kullenbergi uvigerina peregrina assemblage to the oligotrophic abyssal assemblage mainly consisting of agglutinated taxa

late paleocene middle eocene benthic foraminifera on a pacific seamount allison guyot odp site 865 greenhouse climate and superimposed hyperthermal events we investigated the response of late paleocene middle eocene 60 37 5 ma benthic foraminiferal assemblages to long term climate change and hyperthermal events including the paleocene eocene thermal maximum petm at ocean drilling program odp site 865 on allison guyot a seamount in the mid pacific mountains seamounts are isolated deep sea environments where enhanced current systems interrupt bentho pelagic coupling and fossil assemblages from such settings have been little evaluated assemblages at site 865 are diverse and dominated by cylindrical calcareous taxa with complex apertures an extinct group which probably lived infaunally dominance of an infaunal morphogroup is unexpected in a highly oligotrophic setting but these forms may have been shallow infaunal suspension feeders which were ecologically successful on the current swept seamount the magnitude of the petm extinction at site 865 was similar to other sites globally but lower diversity postextinction faunas at this location were affected by ocean acidification as well as changes in current regime which might have led to increased nutrient supply through trophic focusing a minor hyperthermal saw less severe effects of changes in current regime with no evidence for carbonate dissolution although the relative abundance of infaunal benthic foraminifera has been used as a proxy for surface productivity through bentho pelagic coupling we argue that this proxy can be used only in the absence of changes in carbonate saturation and current driven biophysical linking

the ichnogenus rhizocorallium classification trace makers palaeoenvironments and evolution rhizocorallium is one of the oldest known trace fossils with wide distribution through the phanerozoic and all over the world originally introduced from the epicontinental triassic of central germany its high morphological lability gave reason for the subsequent erection of about twenty ichnospecies the study of newly collected material from the type area and many specimens from various collections permits the conclusion that rhizocorallium jenense and rhizocorallium commune are the only valid ichnospecies of rhizocorallium the type ichnospecies r jenense is a comparatively small inclined and heavily scratched firmground burrow with passive fill while r commune consists of extensive more or less horizontal burrows with occasionally scratched marginal tubes and an actively filled spreite between the tubes the faecal pellets coprulus oblongus are typically associated with r commune morphological variations of r commune are captured in ichnosubspecies and varieties of this ichnospecies and can aid a refined reconstruction of palaeoenvironments a review of more than 180 records from the literature reveals the common confusion of both ichnospecies which has consequences for the application of rhizocorallium in facies interpretations the end members of both ichnospecies may be linked by transitional forms which suggests the same kind of trace maker polychaetes are the most likely producers of marine rhizocorallium based on their long ranging occurrence morphological features appearance of faecal pellets associated soft body remains and modern analogues r commune occurs from early cambrian to holocene while r jenense just appears after the end permian mass extinction probably as a consequence of an adapted firmground burrowing lifestyle of its producer fluvial r jenense are probably produced by mayfly larvae in homology to marine polychaete burrows a consequent application of the newly established classification scheme allows for a more rigorous application of rhizocorallium in the reconstruction of palaeoenvironments thus palaeozoic and mesozoic r commune are restricted to the cruziana ichnofacies of shallow marine environments while in cenozoic time similar forms are also found in deep marine deposits r jenense on the other hand is a constituent of the widespread glossifungites ichnofacies and aside from continental environments occurs in peritidal to deep marine deposits several studies have demonstrated the value of rhizocorallium for interpreting sequence stratigraphical surfaces current directions and fluctuations in salinity and oxygen

abundant and diverse early paleozoic infauna indicated by the stratigraphic record marine benthic animals have lived within the sediment since the late precambrian an abundant early paleozoic infauna is indicated by bioturbated zones and diversity of deposit feeder and suspension feeder trace fossil genera burrow depths extended tens of centimetres below the sediment water interface trace fossil evidence of an abundant early paleozoic infauna conflicts with evidence from the shelled fauna which lacks infauna this requires reinterpretation of early paleozoic community structure and raises new questions about interactions between early paleozoic soft bodied and skeletonized animals

recent benthic foraminifera from the eastern south atlantic ocean dependence on food supply and water masses abstract sixty surface sediment samples from the eastern south atlantic ocean including the walvis ridge the angola and cape basins and the southwest african continental margin were analysed for their benthic foraminiferal content to unravel faunal distribution patterns and ecological preferences live stained with rose bengal and dead faunas were counted separately and then each grouped by q mode principal component analysis into seven principal faunal end members then multiple regression technique was used to correlate recent assemblages with available environmental variables and to finally differentiate between four principal groups of environmental agents acting upon the generation of benthic foraminiferal assemblages 1 seasonality of food supply and organic carbon flux rates together with oxygen content in the pore and bottom waters 2 lateral advection of deep water masses 3 bottom water carbonate corrosiveness and 4 energetic state at the benthic boundary layer and grain size composition of the substrate food supply and corresponding dissolved oxygen contents in the pore and bottom waters turned out to be the most important factors which control the distribution pattern of the recent benthic foraminifera at the continental margin in the zone of coastal upwelling and its mixing area benthic foraminiferal assemblages are dominated by stenobathic high productivity faunas characterized by elevated standing stocks low diversities and a large number of endobenthic living species at the continental shelf and upper continental slope the live assemblages are characterized by rectuvigerina cylindrica uvigerina peregrina s 1 uvigerina auberiana and rhizammina spp while the dead assemblages are characterized by cassidulina laevigata bolivina dilatata bulimina costata and b mexicana at the lower continental slope strong influence of high organic matter fluxes on the species composition is restricted to the area off the cunene river mouth where the live assemblage is dominated by uvigerina peregrina s 1 the corresponding dead assemblage by melonis barleeanum and m zaandamae in the adjacent areas of the lower continental slope the biocoenosis is characterized by reophax bilocularis and epistominella exigua which becomes dominant in the corresponding dead assemblage at the walvis ridge and in the abyssal angola and cape basins where organic matter fluxes are low and highly seasonal benthic foraminiferal assemblages reflect both the oligotrophic situation and the deep and bottom water mass configuration the top and flanks of the walvis ridge are inhabited by the rhizammina psammosphaera and r bilocularis live assemblages the corresponding dead assemblages are dominated by g subglobosa on the ridge top and e exigua on the flanks within the highly diverse e exigua dead assemblage several associated epibenthic species coincide with the core of nadw between about 1600 and 3700 m water depth these species include osangularia culter cibicidoides kullenbergi melonis pompilioides bolivinita pseudothalmanni and bulimina alazanensis the assemblages of the abyssal cape and angola basins are characterized by nuttallides umbonifer and a high proportion of agglutinated species these species are adapted to very low organic matter fluxes and a carbonate corrosive environment

the lutetian bartonian transition middle eocene at the oyambre section northern spain implications for standard chronostratigraphy abstract with the aim of finding a potential global stratotype section and point gssp for the base of the bartonian stage an integrated stratigraphic study was carried out in the acebosa fm exposed at the cape of oyambre cantabria spain while the oyambre section does comply with the majority of the requirements of the international commission on stratigraphy several shortcomings were also found which apparently make it unsuitable for the gssp for the base of the bartonian stage an unexpected finding was that the chronostratigraphic calibration of the oyambre planktonic foraminiferal events revealed major discrepancies with the standard timescale the lowest occurrence of globigerinatheka index was found in the upper part of chron c20r and not in the upper part of c20n as depicted in the standard chart being dated at 43 68 ma and not at 42 64 ma the lowest occurrences of turborotalia pomeroli and globigerinatheka euganea were found in the upper part of calcareous nannofossil zone cp14a 40 92 ma and not in the upper part of zone cp13c 42 21 ma finally the highest occurrences of guembelitrioides nuttalli and morozovelloides bandyi were also found in the upper part of zone cp14a 40 68 ma and not in the upper part of zone cp13c 42 07 ma the accuracy of these anomalous results was further substantiated with data from other areas strongly suggesting that the standard eocene chronostratigraphy was in need of amendment the oyambre findings if proven significant at a global scale would have two important chronostratigraphic outcomes firstly the standard eocene planktonic foraminiferal biostratigraphy would need revision as there would be practically no space to accommodate zones e9 and e11 secondly an array of sound biostratigraphic markers would now be defined around chron c19n which has been considered the best marker for the lutetian bartonian boundary thus facilitating correlation of a potential gssp

benthic foraminiferal faunal turnover across the cretaceous tertiary boundary at agost southeastern spain paleoenvironmental inferences we studied upper cretaceous and lower paleogene benthic foraminifera from the agost section southeastern spain to infer paleobathymetrical changes and paleoenvironmental turnover across the cretaceous paleogene k p transition benthic foraminifera indicate uppermost bathyal depths at agost during the abathomphalus mayaroensis biochron from about 400 kyr before the k p boundary through the early plummerita hantkeninoides biochron about 120 150 kyr before that boundary the depth increased to middle bathyal for the remainder of the cretaceous and remained so for the danian part of the studied section parasubbotina pseudobulloides biochron at least 200 kyr after the k p boundary there were no perceivable bathymetrical changes at the k p boundary where v5 of the species became extinct and the species composition of the benthic foraminiferal fauna changed considerably below the boundary infaunal morphogroups constitute up to 65 73 of the faunas directly above the boundary in the black clays of the lower guembelitria cretacea biozone benthic foraminifera are rare several opportunistic taxa e g the agglutinant haplophragmoides sp have short peaks in relative abundance possibly reflecting low oxygen conditions as well as environmental instability with benthos receiving food from short lived local blooms of primary producers above the clays through the end of the studied interval epifaunal morphogroups dominate up to 70 of the assemblages or there is an even mixture or epifaunal and infaunal morphogroups infaunal groups do not recover to pre extinction relative abundances indicating that the food supply to the benthos did not recover fully over the studied interval about 200 kyr after the k p boundary the benthic foraminiferal faunal changes are compatible with the direct and indirect effects of an asteroid impact which severely destabilized primary producers and the oceanic food web that was dependent upon them 2003 elsevier science b v all rights reserved

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

filling the north european early middle eocene ypresian lutetian boundary gap insights from the pyrenean continental to deep marine record abstract the early middle eocene ypresian lutetian transition is represented by a hiatus in many north european sections including those in which the classic stratotypes were originally defined however the global stratotype section and point of the lutetian stage which is still pending definition should be placed at a globally correlatable event included within that unrepresented interval the pyrenean eocene outcrops display sedimentary successions that offer the rare opportunity to analyse the ypresian lutetian boundary interval in almost continuous sections and in very different settings seven reference stratigraphic sections were selected on the basis of their quality and correlated by means of biomagnetostratigraphic data this correlation framework casts light on the sequence of chronostratigraphic events that characterize the ypresian lutetian boundary interval which may prove useful in defining the main correlation criterion of the base of the lutetian all of the pyrenean sections show a similar sedimentary evolution despite being up to 350 km apart from each other containing deposits of different origins intrabasinal carbonate sediments siliciclastic sediments sourced from the iberian plate and terrigenous sediments sourced from the uplifting pyrenees and despite having been accumulated in different sedimentary environments from continental to deep marine and in different geodynamic settings piggy back basin foreland basin and cratonic margin this common evolution can be readily interpreted in terms of a sea level driven depositional sequence whose lowstand and transgressive systems tracts are included within the ypresian lutetian boundary interval the pyrenean ypresian lutetian depositional sequence can reasonably be correlated with depositional sequences from classic north european areas shedding light on the palaeoenvironmental history which in those areas has not been recorded furthermore these depositional sequences may possibly correlate with others from the antarctic ocean and from new jersey as well as with oceanic temperature variations suggesting that they might be the result of climatically driven glacioeustatic sea level changes should this hypothesis prove correct it would confirm previous suggestions that the onset of antarctic glaciations needs to be backshifted to the late ypresian at least

late cretaceous deep water agglutinated foraminiferal assemblages from the north atlantic and its marginal seas the stratigraphic and biogeographic distribution of more than 170 species of deep water agglutinated benthic foraminifers dwaf from the north atlantic and adjacent marginal seas has been compared with paleoenvironmental data e g paleobathymetry oxygenation of the bottom waters amount of terrigenous input and substrate disturbance six general types of assemblages in which deep water agglutinated taxa occur are defined from the turonian to maastrichtian times 1 high latitude slope assemblages 2 low to mid latitude slope assemblages 3 flysch type assemblages 4 deep water limestone assemblages scaglia type 5 abyssal mixed calcareous agglutinated assemblages 6 abyssal purely agglutinated assemblages latitudinal differences in faunal composition are observed the most important of which is the lack or extreme paucity of calcareous forms in high latitude assemblages east to west differences appear to be of comparatively minor importance most dwaf species occur in all studied regions and are thus considered as cosmopolitan biostratigraphic turnovers in the taxonomic content of assemblages are observed in the lowermost turonian mid campanian and in the upper maastrichtian to lowermost paleocene these datum levels correspond to inter regional and time constant paleooceanographic events which probably also affected the deep water benthic biota this allows us to use deep water agglutinated foraminifers for biostratigraphy in the north atlantic sequences deposited below ccd and to geographically extend the currently used zonal schemes which have been established in the carpathian and alpine areas

benthic foraminifera of a miocene canyon and fan abstract we present benthic foraminiferal assemblage data from an exhumed miocene canyon and fan system from the tabernas basin se spain the presence of good indicator taxa and unique assemblages occupying specific environments allows the distinction of slope canyon and fan environments within the tabernas basin by foraminiferal assemblages alone five assemblages are defined on the basis of the occurrence of the indicator taxa primary control on the distribution of these assemblages is consistent with trends of physical disturbance and consequent defaunation barren samples which are predominantly found in high energy parts of the proximal canyon are recognized as representing recently defaunated substrates i e early successional assemblages high diversity assemblages containing a high abundance of agglutinated taxa are recognised in the undisturbed slope sequences as being the regional equilibrium climax fauna intermediate between these end members are assemblages with low diversity dominated by calcareous taxa typically found in the relatively low energy canyon and fan environments which are recognized as representing the middle phases of the ecological succession two further assemblages a low diversity assemblage typified by cassidulina laevigata and bulimina costata and a very low diversity assemblage dominated 10 of all benthic tests by globobulimina spp are restricted to low energy parts of the canyon and fan and are absent from the proximal canyon and slope the composition of these assemblages indicate that nutrient supply oxygenation is a secondary control on the palaeoecology of the canyon system a conceptual model for the recolonisation of defaunated substrates in el buho canyon is proposed in which either an oligotrophic climax assemblage or a eutrophic climax assemblage can be achieved at the completion of recolonisation of defaunated substrates depending on environmental conditions

palaeoenvironmental and ecological interpretation of the trace fossil rhizocorallium based on contained iron framoboids upper devonian south china the trace fossil rhizocorallium commune is abundant in shallow marine deposits of the upper devonian frasnian tuqiaozi formation in ganxi sichuan province south china it consists of u shaped spreite burrows developed more or less parallel or slightly inclined to the bedding of marly limestone four types of iron framboids mostly oxygenated from pyrite framboids were found within the rhizocorallium burrow including 1 smooth sheathed spherical 2 prismatic 3 octahedral and 4 pyritohedral submicron crystals chemically the submicron crystals mainly consist of iron sulphur oxygen and carbon the iron framboids represent the stage of evolution of their original pyrite framboids from irregular morphologies and spherical framboids to octahedral and pyritohedral habits due to the activity of sulphate reducing bacteria no similar framboids were observed outside rhizocorallium therefore it is likely that sulphate reducing bacteria colonised the rhizocorallium spreite and marginal tube within a dysoxic environment with increasing degree of oxygenation of pore water the pyrite framboids were partly oxygenated into iron framboids and by exceptional circumstances preserved the original morphology of the crystals furthermore it is proposed that the investigated rhizocorallium was constructed by its trace maker for gardening with multifunctional purpose where different microbial colonies were planted and cultured in the marginal tube and spreite on the mutual basis of food supply and redox conditions these features indicate that a combined deposit feeding and gardening model may apply for the construction of rhizocorallium commune from the devonian of ganxi the responsible trace maker probably was a worm like organism such as a polychaete

an outer ramp to basin plain transect interacting pelagic and calciturbidite deposition in the eocene oligocene of the tuscan domain adria microplate italy abstract the interaction of ramps basin plains and turbidite systems on the scale of tens of km has been rarely observed in fossil examples deep marine eocene oligocene beds are exposed in the axial zone of the chianti mountains italy and compose a regionally continue stratigraphic succession known as the scaglia toscana formation the formation was deposited in the tuscan domain of the adria microplate this research aims at depicting its depositional architecture and evolution in the type area stratigraphic and sedimentologic analyses were performed on a ca 25 km long transect that includes depositional systems sectioned both in the down and along dip directions shaly carbonate deposits compose a complex of interacting ramps basin plains and turbidite floor fan systems ramp deposits accumulated above the lysocline and in oxic conditions basin plain beds were deposited below the lysocline and were subject to episodes of oxygen depletion turbidity flows fed elongate fan lobes characterized by poor channelisation the basin palaeogeography hampered the development of slope apron turbidite systems the eocene oligocene geodynamic setting of the tuscan domain was characterized by the evolution of a peripheral bulge and by the early structuring of a foredeep basin syn sedimentary tectonism acted a primary role in the basin scale arrangement however other mechanisms also contributed to the local facies distribution including the disposition of sediment source areas and intrabasinal confinement morphologies as well as relative oscillations of the depositional surface with respect to the lysocline and oxycline

trophic control of benthic foraminiferal abundance and microhabitat in the bathyal gulf of lions western mediterranean sea surface sediment was sampled at two bathyal sites in the southwestern gulf of lions in the western mediterranean sea in february and august 1997 to study the distribution and microhabitat of living rose bengal stained deep sea benthic foraminifera both standing stock and diversity of the faunas and the microhabitat of distinct species mirror the trophic situation and the depth of the oxidised layer at the different sites our results suggest that the faunas do not comprise highly opportunistic species and are adapted to rather stable environments in the axial channel of the lacaze duthiers canyon organic matter fluxes are enhanced due to advective transport of organic matter resulting in elevated oxygen consumption rates in the surface sediment and a rather thin oxidised layer the corresponding benthic foraminiferal fauna is characterised by rather high standing stock and diversity and a well developed deep infauna in addition to freshly deposited phytodetritus more degraded organic matter seems to be an important food source in contrast at the open slope organic matter fluxes and oxygen consumption rates in the surface sediment are lower and the oxidised layer is much thicker than inside the canyon the corresponding benthic foraminiferal fauna comprises mainly epifaunal and shallow infaunal species with much lower standing stocks and clear differences between february and august in august standing stocks are higher and the average living depths of most species shift towards the sediment surface these differences can be attributed to patchiness or represent a seasonal trophic signal

contrasting environmental effects of astronomically driven climate change on three eocene hemipelagic successions from the basque cantabrian basin several processes can contribute to the formation of hemipelagic limestone marl alternations as a consequence of astronomically driven climate change the aim of this work is to decipher which environmental factors governed the formation of three eocene hemipelagic successions of the basque cantabrian basin using a comprehensive set of physical and bulk carbonate geochemical data bed thickness mineralogy caco3 13c and 18o the results show that the significance of several environmental processes varied depending on the palaeogeographic setting and eccentricity modulated precessional seasonality in the sopelana starved deep sea basin limestones were formed as a consequence of high pelagic carbonate productivity during periods of warm seawater and sluggish circulation which corresponded to periods of low seasonality summers at aphelion conversely marls accumulated when pelagic carbonate productivity decreased during periods with cooler waters and more vigorous circulation which occurred when seasonality was higher summers at perihelion in the gorrondatxe submarine fan fringe marls accumulated when high seasonality produced significant continental rainfall and runoff causing the dilution of pelagic carbonate sedimentation with terrigenous supplies in the oyambre upper slope marls also accumulated when seasonality was high as pelagic carbonate productivity decreased due to both the expansion of low salinity waters on the ocean surface and the increase in continentally derived nutrients which caused detrimental seawater conditions for calcareous plankton both in gorrondatxe and oyambre limestones accumulated when boreal summer at aphelion caused low seasonality which allowed relatively stable conditions to prevail at minimum eccentricity when precession driven seasonality contrast diminished changes in pelagic carbonate productivity were significant in the three sections on the contrary at maximum eccentricity when seasonality peaked due to summers occurring at perihelion the effects of other environmental processes such as continental and oceanic currents became influential however the influence of these processes minimized when summertime coincided with aphelion at maximum eccentricity and seasonality was weakest this article is protected by copyright all rights reserved

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

irregular glacial interstadials recorded in a new greenland ice core the greenland ice sheet offers the most favourable conditions in the northern hemisphere for obtaining high resolution continuous time series of climate related parameters profiles of 18o 16o ratio along three previous deep greenland ice cores1 3 seemed to reveal irregular but well defined episodes of relatively mild climate conditions interstadials during the mid and late parts of the last glaciation but there has been some doubt as to whether the shifts in oxygen isotope ratio were genuine representations of changes in climate rather than artefacts due to disturbed stratification here we present results from a new deep ice core drilled at the summit of the greenland ice sheet where the depositional environ ment and the flow pattern of the ice are close to ideal for core recovery and analysis the results reproduce the previous findings to such a degree that the existence of the interstadial episodes can no longer be in doubt according to a preliminary timescale based on stratigraphic studies the interstadials lasted from 500 to 2 000 years and their irregular occurrence suggests complexity in the behaviour of the north atlantic ocean circulation

benthic foraminiferal assemblages from the eastern weddell sea between 68 and 73 s distribution ecology and fossilization potential surface sediment samples taken with a vented box corer from the eastern weddell sea on four profiles perpendicular to the continental margin have been investigated for their benthic foraminiferal content the live fauna was differentiated from empty tests comprising the foraminiferal death assemblage based on the dead assemblages potential fossil assemblages were calculated to facilitate the analogy with late neogene core material five distinct live assemblages inhabit the continental margin today six dead assemblages and five potential fossil assemblages respectively correspond to these biocoenoses a predominantly calcareous live fauna dominated by trifarina angulosa is correlated with strong bottom currents and sandy sediments at the shelf break and on the uppermost continental slope below this on the upper slope down to 2000 m water depth the predominantly calcareous bulimina aculeata assemblage coincides with the core of warm 0 c weddell deep water and with fine and more organic rich sediments these calcareous live assemblages completely change composition during early diagenesis because of calcite dissolution within the uppermost sediment which depends largely on the grain size distribution of the sediment and the fluxes of organic matter therefore a still calcareous t angulosa dominated fossil assemblage indicates the sandy substrates on the shelf break and the upper slope whereas the deeper slope with hemipelagic calm sedimentation and with high fluxes of organic matter is indicated by martinottiella nodulosa the characteristic arenaceous fossil remnant of the former predominantly calcareous live b aculeata fauna on a continental terrace between 2500 and 3500 m water depth cribrostomoides subglobosus dominates the live fauna but because of rapid disintegration of the empty tests of this agglutinated species a predominantly calcareous fauna characterized by oridorsalis umbonatus and epistominella exigua comprises the dead assemblage and the potential fossil assemblage respectively on the lower continental slope between the carbonate lysocline 3500 m and the carbonate compensation depth 4000 m tests of nuttallides umbonifer are the characteristic dead and potential fossil remnants of a former predominantly arenaceous live fauna which is associated with the lower part of the antarctic bottom water aabw this corroborates earlier investigations suggesting a relationship between the carbonate corrosiveness of water masses and the distribution of n umbonifer this is important for inferring paleo routes and estimates of paleo production rates of aabw during the neogene

benthic foraminiferal response to changes in mining pattern a case study from the zuari estuary goa india being sensitive to environmental changes foraminifera have been extensively used to monitor pollution level in the marine environment including the effect of mining in coastal areas in the goa state of india the rejects from opencast mining on land largely find their way to the estuaries as washout during monsoon additionally the mormugao port at the mouth of the zuari estuary is the hub of activities due to the transport of ore from hinterland areas by barges and its subsequent loading for export on the directive of the supreme court of india all the mining related activities abruptly stopped throughout india including that in goa in 2012 and got reinstated in 2015 therefore it provided a fit case to test the effectiveness of benthic foraminifera as an indicator of environmental impact due to mining activities a total of ten surface sediment samples from five locations in zuari estuary were collected from a depth range of 4 5 8 5 m in the years of 2013 and 2016 and were analyzed for both the living stained and dead benthic foraminifera the year 2013 represents a time interval immediately after the closure of extensive mining activity and the sampling during 2016 represents minimal mining the living benthic foraminiferal abundance was higher 19 54 g sediment during 2013 and decreased substantially during 2016 3 22 g sediment suggesting an adverse effect of activities associated with mine closure on benthic foraminifera additionally the relative abundance of ammonia was also significantly low during the year 2016 the temporal variation in dead foraminifera was however different than that of the living foraminifera the differential response was attributed to the terrigenous dilution as a result of change in sedimentation rate therefore we conclude that living foraminifera correctly incorporate the changes in mining pattern and may be used as an effective tool to monitor the impact of mining we further suggest that the potential counter effect of terrigenous dilution on total and living benthic foraminiferal population should be considered while interpreting temporal variations in foraminiferal abundance in marginal marine settings

substrate control of lower cambrian trace fossils from bornholm denmark abstract a ten meter thick sequence within the lower cambrian succession from snogebaek harbour to broens odde bornholm contains abundant trace fossils throughout the systematics of some of the ichnogenera are briefly discussed in particular buthotrephis and a new form of diplocraterion the trace fossils can be subdivided into four associations the skolithos diplocraterion rhizocorallium and teichichnus buthotrephis associations the recurrence of these associations can be correlated with changes in substrate in particular the diplocraterion association in the middle and upper part of the broens odde member exposed here occurs only in storm deposits

the pliocene climatic and environmental evolution of southeastern australia evidence from the marine and terrestrial realm abstract during the pliocene the global climate fluctuated markedly with the expansion and contraction of the northern and southern hemisphere ice sheets the signals of this change are well preserved in the thick up to 1 km seaspray group cool water carbonate sediments in the gippsland region and associated thin terrestrial deposits in southeastern australia this study uses seismic facies foraminiferal proxy data and palaeobotanical data to chart the pliocene climate and environmental change in the marine and terrestrial realms of southeastern australia complex submarine canyoning occurred at the shelf upper bathyal transition during the pliocene in gippsland low energy pelagic marl wackestone packstone characterise canyon and inter canyon environments in the earliest pliocene depositing plankton oozes with interbedded calciturbidites from upper early pliocene to late pliocene time high energy limestone grainstone facies infilled these submarine canyons associated with progradation of the succession from outer to middle shelf palaeoenvironments plankton proxy data suggest cool conditions in the basal part of early pliocene relatively stable warmer marine conditions prevailed throughout most of the early pliocene corresponding to a period of globally low 18o values in the oceans associated with minor antarctic ice sheet expansion from middle to late pliocene time marked fluctuations in the abundance of cool and warmer water plankton taxa occurred corresponding to a time of global marine 18o fluctuations and generally heavier 18o values associated with the expansion of the antarctic ice and northern hemisphere ice sheets upwelling is interpreted to have occurred throughout much of the warmer early pliocene caused by a more northerly compared to today positioned and weaker subtropical front upwelling was prevalent in the outer shelf to upper slope facies at the palaeo bass canyon and the subtropical front migrated northwards to gippsland during late pliocene glacial periods terrestrial palaeobotanical records indicate a shift from widespread araucarian forests and rainforest including tropical taxa now extinct in the region to a landscape by the end of the late pliocene similar to that of the present day with a mosaic of eucalyptus acacia casuarinaceae sclerophyllous forests and open vegetation with local areas of nothofagus dominated cool temperate rainforests palaeobotanical proxy data indicate that regional climate oscillated between warm wet and cool dry phases with an overall cooling drying trend through the pliocene earliest pliocene climates in southeast australia were warm wet with a summer rainfall peak mean annual temperature mat 2 4 c higher than present mean annual precipitation map 50 70 higher than present whereas terminal late pliocene climates were drier cooler with a winter rainfall peak mat 0 2 c higher than present map 0 30 higher than present

early eocene climatic optimum environmental impact on the north iberian continental margin the early eocene climatic optimum which constituted the peak of the long term early cenozoic global warming had a significant impact on the environmental evolution of terrestrial and oceanic areas surprisingly however its influence on continental margins is poorly known new insights are provided from a sedimentological stable isotope mineralogical and micropaleontological study of an 1100 m thick lower middle eocene deep marine succession that accumulated on the north iberian continental margin the early eocene climatic optimum is represented by a 410 m thick interval characterized by scarcity of hemipelagic limestones abundance of dark marls which record a reduction in calcium carbonate content and an increase in kaolinite and the occurrence of conspicuous red layers with high siderite and pyrite content series of stratigraphically significant events frame the early eocene climatic optimum based on this analysis the environmental influence of the early eocene climatic optimum started at 52 6 ma and lasted 2 3 m y its onset is marked by rapid drops in 13c and 18o which record the addition of 13c depletedcarbon into the ocean atmosphere system for 80 k y and a concomitant warming a hotter climate and a perennial rainfall regime increased the supply of terrestrial clays organicmatter and iron oxides into the sea eventually these changes affected the deepsea bottom 270 k y after the onset of the early eocene climatic optimum creating conditions in which opportunistic benthic foraminifera thrived and leading to increased methanogenesis in the subsurface which caused the formation of siderite a subsequent gradual recovery culminated abruptly at 50 3 ma with a global cooling episode which is locally recorded by the accumulation of lowstand resedimentation deposits 2015 geological society of america

eocene bartonian benthic foraminifera and paleoenvironmental changes in the western tethys abstract the eocene was a period of intense climate variability and the response of deep sea biota is still poorly understood especially across certain understudied intervals from the middle eocene we present new benthic foraminiferal data from a bartonian marine sequence deposited in the western tethys ocean torre cardela section spain and determine the biotic and paleoenvironmental turnover the assemblages indicate a middle to lower bathyal depth of deposition and they contain allochthonous taxa e g asterigerinids that were transported from shallower settings a detrended correspondence analysis dca performed on the total assemblage differentiates the autochthonous and allochthonous taxa supporting the idea of different provenience we suggest that the latter were likely transported downslope by currents quantitative analyses of the autochthonous assemblages show a strong dominance of calcareous infaunal taxa mainly bolivinids which point to a high flux of organic matter to the seafloor bolivinoides crenulata the most common species is associated with inputs of refractory organic matter and high energy environments five intervals were differentiated based on changes in the relative abundance of taxa two intervals b and d show the highest percentages of allochthonous taxa and b crenulata we suggest that enhanced current activity not only transported allochthonous taxa but also brought in refractory organic matter to the seafloor which was consumed by opportunistic taxa during these two intervals we conclude that benthic foraminiferal assemblages at torre cardela were strongly controlled by the amount and type of organic matter reaching the seafloor which were in turn affected by sedimentary and ultimately by climatic factors

distribution of recent benthic foraminifera along continental slope of the sunda shelf south china sea the distribution of live rose bengal stained and dead benthic foraminiferal distribution 150 mu m was investigated in sediment surface samples 0 1 cm from the winter upwelling region off borneo on the continental slope of the sunda shelf and from the continental slope of southern vietnam shelf the benthic foraminiferal faunas of both areas are highly diverse h s 2 91 4 25 for living and 4 01 4 38 for dead a canonical correspondence analysis proved that bathyal assemblages are most strongly influenced by the decreasing rates of organic carbon flux with increasing water depth resulting in a pronounced depth related succession of assemblages correlation between estimated c org flux and factor 1 loadings of the cca for modem dead foraminiferal assemblages is very good r 2 0 96 thus a local transfer function y 5 0289x 6 8142 for estimating paleo c org flux rates from the down core samples has been successfully developed for the continental slope of the sunda shelf four benthic foraminiferal biofacies were recognised within the studied depth ranges upper bathyal biofacies siphotextularia foliosa cibicidoides robertsonianus well supplied and well oxygenated middle bathyal biofacies uvigerina auberiana nuttallides rugosus located within the oxygen minimum zone uppermost lower bathyal biofacies lagenammina difflugiformis uvigerina peregrina and lower bathyal biofacies paratrochammina challengeri parrelloides bradyi from the relatively well oxygenated but food limited environment c 2009 elsevier b v all rights reserved

the miocene palaeoenvironmental and palaeoceanographic evolution of the gippsland basin southeast australia a record of southern ocean change abstract the gippsland basin in southeastern australia preserves up to 2 5 km thick tertiary to recent marine carbonate sediments included in the seaspray group during the neogene the seaspray group carbonates of the mackerel and flounder petroleum fields lay at the shelfal to bathyal palaeoenvironmental transition an ideal palaeoceanographic setting to study the neogene history of events in the evolving southern ocean seismic foraminiferal and facies analyses of the miocene seaspray group sediments at the mackerel 1 and flounder 1 wells have revealed the following palaeoenvironmental history of the area relatively cool to temperate upwelling conditions prevailed in the area during the earliest miocene during this time low energy upper slope globigerina ooze calcareous mudstone was deposited in the oxygen minimum zone during the early to lower middle miocene upper slope marl was deposited in oligotrophic conditions the presence of neritic subtropical foraminifera and abundant shallow and deep dwelling warm to cool temperate plankton in the upper slope suggests that warm poorly stratified oceanic conditions prevailed in the region this upper early miocene warm phase and mid miocene climatic optimum in gippsland corresponds to a time when global ocean conditions were much warmer and less vertically and latitudinally stratified than at present these oceanic conditions were associated with a reduced east antarctic ice sheet a higher sea level a relatively weak antarctic circumpolar current and weak atmospheric and wind driven circulation during the upper middle miocene to late miocene cool phase after c 14 5 ma strong upwelling and cooler oceanic conditions prevailed in the outer shelf to upper slope canyon facies in gippsland the occurrence of common deep dwelling plankton taxa in this interval suggests that regional oceanic conditions became more vertically stratified during this time from 14 5 and 5 million years ago the middle to late miocene palaeoenvironmental change recorded in seaspray group sediments corresponds to global cooling and major antarctic ice sheet expansion when the world s oceans became more vertically and latitudinally stratified from around 14 5 million years the transition from a warm miocene optimum to cooler oceanic conditions was associated with a strengthened antarctic circumpolar current and more intense wind driven atmospheric circulation in the southern ocean

distribution patterns of benthic foraminifera across the ypresian lutetian gorrondatxe section northern spain response to sedimentary disturbance article we present a study of benthic foraminiferal assemblages from an ypresian lutetian distal submarine fan system in the lower bathyal gorrondatxe section basque cantabrian basin northern spain the objective of our study is to analyze the benthic foraminiferal distribution patterns and their response to sedimentary disturbance and related factors assemblages contain a high percentage of allochthonous taxa such as asterigerinids and other shallow water taxa which were transported downslope by turbidity currents detailed quantitative analyses supported by r mode cluster and detrended correspondence analyses after removing allochthonous taxa from the foraminiferal counts allowed us to identify 6 assemblages that are divided into two groups related to the turbidite content in the gorrondatxe section assemblages 1 characteristic of the turbidite poor intervals with low sedimentary disturbance include assemblage 1a with highly diverse common middle lower bathyal calcareous taxa assemblage 1b with common agglutinated taxa mainly trochamminids and assemblage 1c characterized by calcareous taxa that are also common in the turbidite rich interval assemblages 2 characterized by a high dominance prevail in the turbidite rich interval and include assemblage 2a characterized by the dominance of infaunal bolivinids and epifaunal cibicids assemblage 2b typified by moderate to low diversity and dominated by deep infaunal globobulimina species and assemblage 2c typified by very abundant suspension feeding astrorhizids the high abundance of bolivinids and globobulimina species may be related to an enhanced input of low quality organic matter transported by turbidity currents to the seafloor representing different stages of recolonisation after disturbance and different energy regimes high current activity was probably responsible for the abundance of cibicids while moderate to low diverse and high dominance assemblages characterize the recolonisation of the substrate after disturbance we conclude that sedimentary disturbance and other related factors such as current activity resuspension of sediments at the seafloor and supply of organic matter and its quality played an important role in the distribution of benthic foraminifera inthe gorrondatxesection the identification of allochthonous taxa emerges as an essential aspect of the study of environments with sedimentary disturbance

microfossil turnover across the uppermost danian at caravaca spain paleoenvironmental inferences and identification of the latest danian event abstract the latest danian event lde or top chron c27n hyperthermal event has been identified in the caravaca section southern spain by means of calcareous nannofossil biozones subzone ntp7b and the recognition of a prominent negative 0 6 per mille carbon isotope excursion measured in benthic foraminiferal tests this is the first time that this danian hyperthermal event has been identified in a deep water middle to lower bathyal setting from the western tethyan realm the analysis of benthic foraminiferal assemblages shows gradual changes in the assemblages prior to the onset of the lde and an increase in food supply to the seafloor during the lde in agreement with results from shallower southern tethyan settings the benthic assemblage changes across the lde at caravaca share some characteristics with other hyperthermal events including the negative carbon isotope excursion the increased abundance of buliminids or the common occurrence of a aragonensis an opportunistic species that proliferated during other paleogene hyperthermal events in addition the increased abundance of nuttallides truempyi a dissolution resistant form that thrived during the paleocene eocene thermal maximum and the abundance of calcareous infaunal morphogroups which calcify in less carbonate undersaturated pore waters indicate slightly caco3 corrosive bottom waters during the lde turnover of calcareous plankton across the lde is similar to other sites globally distributed including the evolution of photosymbiotic foraminiferal lineages and the radiation of the nannofossil fasciculiths group the occurrence of innovative morphostructures diantholitha and lithoptychius towards the base of the lde may indicate a more efficient biological pump this hypothesis is supported by increased percentages of benthic infaunal morphogroups and a decrease in the abundance of oligotrophic species a reworked interval has been identified immediately above the lde higher up in the section benthic and planktic assemblages from the post lde interval point to the recovery of the environmental conditions including a decrease in the food supply to the seafloor

pronounced biotic and environmental change across the latest danian warming event lde at shatsky rise pacific ocean odp site 1210 abstract the early paleogene is characterized by numerous hyperthermals transient nuttallides umbonifera dominated assemblage yet 200 kyr before the lde benthic foraminiferal assemblages with increased relative abundance of endobenthic morphotypes and benthic foraminiferal accumulation rates indicate a slightly enhanced food flux a temperature increase 40 kyr before the first carbon isotope excursion cie of the lde lde1 is associated with a rise in abundance of tappanina selmensis suggesting episodic input of fresh phytodetritus at the start of lde1 and through the second cie lde2 the seafloor returned to more oligotrophic conditions between 220 and 430 kyr after the onset of the lde a second phase of episodic fresh phytodetritus input is suggested by a renewed dominance of t selmensis although the patterns of faunal change during hyperthermals relate to local conditions circulation patterns the magnitude of faunal change is probably more related to an absolute temperature threshold

mid lower bathyal benthic foraminifera of the campos basin southeastern brazilian margin biotopes and controlling ecological factors abstract the benthic foraminiferal assemblages recovered from 41 surface sediment samples of the campos basin southeastern brazilian continental margin were analyzed in order to understand their distribution patterns and ecological preferences living and dead specimens of benthic foraminifera were selected for identification and quantitative analysis from the 63 to 125 m the 125 m and the combined 63 m size fractions q mode cluster and canonical correspondence analyses for all size fractions show the dissimilarity between the samples collected on the middle slope group 1 750 to 1050 m water depth and those collected on the lower slope group 2 1350 to 1950 m water depth food supply energy state stability at the benthic pelagic boundary and the grain size of the substrate seem to be the most important environmental factors determining the distribution pattern of the benthic foraminiferal assemblages in the deep sea the middle slope between 750 and 1050 m water depth is characterized by the dominance of different species of the genus bolivina cassidulina laevigata and globocassidulina subglobosa the occurrence of these species in association with cibicidoides kullenbergi epistominella exigua and uvigerina proboscidea seems to be related to seasonal organic matter fluxes relatively oxic bottom waters strong bottom currents and sandy sediments the lower slope between 1650 and 1950 m water depth is inhabited by a microfauna with different characteristics composed of preferentially epifaunal or shallow infaunal deposit feeding species e g bolivina spp eponides weddellensis lenticulina cultrata and suspension feeders that are adapted to oligotrophic conditions and high dissolved oxygen levels in the bottom waters e g rhabdammina spp rhizammina sp

benthic foraminifera at the cretaceous tertiary boundary around the gulf of mexico cretaceous tertiary k t boundary sections in northeastern mexico contain marly formations separated by a controversial clastic unit benthic foraminifera in seven sections indicate middle and lower bathyal depths of deposition for the marls with the exception of the upper bathyal northernmost section mixed neritic bathyal faunas were present in the clastic unit indicating redeposition in the deep basin by mass wasting processes resulting from the k t bolide impact in the gulf of mexico benthic foraminifera in the mexican sections and at other deep sea locations were not subject to major extinction at the time of impact but there were temporary changes in assemblage composition benthic faunas indicate welloxygenated bottom waters and mesotrophic conditions during the late maastrichtian and increased food supply during the latest maastrichtian the food supply decreased drastically just after the k t boundary possibly because of the collapse of surface productivity cretaceous and early paleogene benthic foraminifera however did not exhibit the benthic pelagic coupling of present day faunas as documented by the lack of significant extinction at the k t collapse of surface productivity much of the food supplied to the benthic faunas along this continental margin might have been refractory material transported from land or shallow coastal regions the decrease in food supply at the k t boundary might be associated with the processes of mass wasting which removed surface food rich sediment benthic faunas show a staggered pattern of faunal recovery in the lowermost paleogene consistent with a staged recovery of the vertical organic flux but also with a gradual buildup of organic matter in the sediment

environmental distribution of recent benthic foraminifera on the northeast united states continental slope several bathymetrically consistent recent benthic foraminiferal biofacies have been recognized from the continental slope south east of cape cod faunal assemblages are dominated by globobulimina bulimina upper slope less than 1 000 m and uvigerina peregrina lower slope uppermost rise water depths between 1 000 and 2 500 m the globobulimina bulimina assemblage coincides with the oxygen minimum zone this agrees with the occurrence of globobulimina in mediterranean sapropels organic rich sediments deposited under anoxic conditions previous studies have noted the association of u peregrina with bathyal water depths deep water temperatures of 3 to 4 c and water of low oxygen content however correlations between abundance of u peregrina and water depth or temperature are not the same everywhere and no correlation with dissolved oxygen in the water column is seen on the united states continental slope and rise the highest abundances of u peregrina coincide with maxima of organic carbon and silt within the slope sediments this suggests that the distribution of u peregrina in this region may be influenced more by low oxygen in the sediments rather than by low oxygen content of the overlying water

deep sea benthic foraminiferal turnover across early eocene hyperthermal events at northeast atlantic dsdp site 550 abstract several extreme warming events called hyperthermals superimposed the warming trend of the early paleogene deep sea benthic foraminifera suffered major extinction during the most severe of those events the paleocene eocene thermal maximum but their response to the following less severe hyperthermals has been documented at very few locations we evaluate and compare the benthic foraminiferal assemblages across etm2 and h2 events at dsdp site 550 in the ne atlantic ocean the cie and carbonate dissolution were more severe during etm2 than during the h2 event early eocene benthic foraminiferal assemblages were moderately diverse and strongly dominated by calcareous taxa and they consisted of mixed infaunal and epifaunal morphogroups they responded similarly to etm2 and h2 events showing a decrease in absolute abundance an increase in the relative abundance of agglutinated taxa indicative of more carbonate corrosive waters and a marked decrease in the percentage of bolivinoides decoratus suggesting a lower food supply during hyperthermals however some differences in their response were also noted oligotrophic taxa such as nuttallides truempyi and quadrimorphina profunda increased in relative abundance during early etm2 whereas globocassidulina subglobosa and osangularia sp 1 opportunistic species which may indicate pulsed food inputs peaked during the h2 event we conclude that both hyperthermal events represent a general disruption of an overall meso oligotrophic environment with less food reaching the seafloor combined with increased caco3 corrosivity of bottom waters we did not find clear evidence for decreasing primary productivity during the hyperthermal events and the apparent low food delivery to the seafloor may have been related to an increase in benthic foraminiferal metabolic rates due to the higher temperatures with a more severe lack of food during etm2 than during h2 the benthic foraminiferal response thus appears to be scaled to the magnitude of hyperthermals