eolian deposition in the northeast pacific ocean cenozoic history of atmospheric circulation the mass accumulation rate and grain size distribution of the total eolian component of north pacific pelagic clays have been used to evaluate changes in eolian sedimentation and in the intensity of atmospheric circulation that have occurred during the past 70 m y eolian deposition was relatively low approximately 12 mg cm2 1 000 yr in the late cretaceous and paleocene reflecting an increasingly humid environment a peak in accumulation rates across the paleocene eocene boundary may be the result of episodic volcanism in mexico a sharp decrease in grain size across the paleocene eocene boundary is not readily interpreted fine eolian grain size and the low accumulation rates averaging 8 mg cm2 1 000 yr in the eocene and early oligocene are in agreement with low early tertiary thermal gradients and less vigorous atmospheric circulation large increases in grain size between 37 and 30 m y ago 20 and 10 m y ago and 5 m y ago to the present suggest that atmospheric circulation intensified by a factor of 1 5 1 8 and 1 4 respectively at these times eolian accumulation rates increased from 8 mg cm2 1 000 yr at the eocene oligocene boundary to approximately 25 mg cm2 1 000 yr at the end of the miocene with significant changes at 25 and 13 m y ago increased rates about 25 m y ago probably reflect movement of the core site into the influence of the westerlies and the increase 13 m y ago appears to be a response to steepening thermal gradients and intensifying atmospheric circulation resulting from major expansion of antarctic ice in the mid miocene along with a general increase in global aridity in the late cenozoic an order of magnitude increase in eolian accumulation rates 25 to 226 mg cm2 1 000 yr in pliocene pleistocene time coincides with the onset of northern hemisphere glaciation and consequent climatic deterioration the large increase in accumulation rates in pliocene pleistocene time coincides with a relatively smal increase in the intensity of atmospheric circulation compared to that in oligocene and miocene time suggesting that the increased deposition rates were the result of an increase in global aridity in glacial times rather than a further increase in the vigor of the global wind systems

a different perspective on glauconite as a chronometer for geologic time scale studies there are advocates of the use of glauconite as a chronometer for geologic time scale studies who insist that if the geohistory of the sample in question is known in detail one can ascertain before hand that the sample will yield a radiometric result that is accurate in the geological sense examples are presented indicating that while some glauconite samples may yield the correct age within their assigned analytical uncertainties when compared to high temperature minerals others clearly do not and are too young by varying degrees the outright acceptance of published results on glauconite can result in erroneous age estimates of various biostratigraphic levels and stage or epoch boundaries

enhanced terrestrial weathering runoff and surface ocean carbonate production during the recovery stages of the paleocene eocene thermal maximum 1 the carbonate saturation profile of the oceans shoaled markedly during a transient global warming event known as the paleocene eocene thermal maximum petm circa 55 ma the rapid release of large quantities of carbon into the ocean atmosphere system is believed to have triggered this intense episode of dissolution along with a negative carbon isotope excursion cie the brevity 120 220 kyr of the petm reflects the rapid enhancement of negative feedback mechanisms within earth s exogenic carbon cycle that served the dual function of buffering ocean ph and reducing atmospheric greenhouse gas levels detailed study of the petm stratigraphy from ocean drilling program site 690 weddell sea reveals that the cie recovery period which postdates the cie onset by 80 kyr is represented by an expanded 2 5 m thick interval containing a unique planktic foraminiferal assemblage strongly diluted by coccolithophore carbonate collectively the micropaleontological and sedimentological changes preserved within the cie recovery interval reflect a transient state when ocean atmosphere chemistry fostered prolific coccolithophore blooms that suppressed the local lysocline to relatively deeper depths a prominent peak in the abundance of the clay mineral kaolinite is associated with the cie recovery interval indicating that continental weathering runoff intensified at this time as well robert and kennett 1994 such parallel stratigraphic changes are generally consonant with the hypothesis that enhanced continental weathering runoff and carbonate precipitation helped sequester carbon during the petm recovery period e g dickens et al 1997 zachos et al 2005

abyssal circulation and benthic foraminiferal changes near the paleocene eocene boundary a major change in cenozoic deep sea benthic foraminifera occurred in the atlantic indian and pacific oceans near the paleocene eocene boundary benthic foraminiferal abundance changes began at about 61 5 ma at pacific deep sea drilling project dsdp site 577 a major extinction event followed at 58 57 ma between zones p6a and p6b and a series of first appearances continued until circa 55 5 ma zone p6c these faunal changes occurred during a 6 c warming of pacific bottom water and may indicate that the primary cause was changing temperature other potential causes of the faunal turnover include global changes in surface ocean productivity and changing bottom water source regions comparison of benthic and planktonic 13c records requires no change in the ratio of oceanic phosphorous to carbon during the late paleocene to early eocene which weakens the case for but does not disprove a change in surface ocean productivity at this time interbasinal comparisons of benthic foraminiferal 13c records document that water with high 13c values filled the cape basin during the late paleocene and possibly the early eocene circa 61 57 ma but apparently did not extend into the western basins of the atlantic this pattern suggests a supply of antarctic source water for the cape basin and possible tectonic isolation of the western atlantic basins during at least part of the late paleocene carbon isotope comparisons show that bottom water supply to the cape basin was reduced in the early eocene eolian grain size data suggest that a decrease in zonal wind intensity occurred at the end of the paleocene these late paleocene climatic changes bottom water warming and decreased wind intensity correspond with evidence for an important global tectonic reorganization and extensive subaerial volcanism which may have contributed to climatic warming through increased supply of co2

the use of mineralogic techniques as relative age indicators for weathering profiles on the atlantic coastal plain usa abstract textural geochemical and mineralogic study of soils and weathering profiles has led to the practice of applying varioys weathering parameters as relative age indicators in our studies examined the entire thickness of weathered sediment i e the weathering profile for evidence of weathering induced changes in both sand and clay sized mineralogy and used two techniques for relative age determinations these techniques were developed as tools to support geologic mapping one of our techniques for determining relative ages is based on the depth of weathering as recorded by progressive loss of denrital sand sized minerals upward in the weathering profile this is our preferred tool especially in areas where weathering profiles have been truncated we have found a gradual trend of increasing loss of labile sand sized minerals e g hornblendes feldspars and increasing depth of weathering with increasing age of the deposit of significance to many research programs this technique does not require expensive instruments such as an x ray diffractometer our other technique depends on accumulation of stable secondary clay sized minerals in the upper part of the weathering profile in our study area on the atlantic coastal plain of the united states the stable assemblage consists of vermiculite kaolinite gibbsite and iron oxides and hydroxides this technique can be effective for relative age determinations where profiles have not been truncated and can provide useful information on depositional and erosional history however in areas of widespread erosion and profile truncation such as the carolinas the utility of this technique for relative age determinations is limited there soils were partially or completely removed in many localities in relatively recent times

tide gage response to tsunamis part ii other oceans and smaller seas abstract extending previous work in the north pacific tsunami response was examined in the atlantic and indian oceans and in three smaller seas with the objective of exploring scale effects energy diffusing from the chilean tsunami of 22 may 1960 was tracked through windows around antarctica into all three oceans simultaneously reaching maximum intensity about 39 h after quake time in smaller seas spectral response was again characteristically an exacerbation of normal background with principal energy in the fundamental pumping mode of the local coastal shelf subsequent to diffusion isotropic energy decay was uniformly exponential except that the diffusion and decay e folidng times were different in each sea an ad hoc energy flux decay model with a constant linear friction coefficient suffices to explain the observed decay times in terms of basin geometries the model has several spinoffs it accounts for about half the observed coastwise variation in tsunami intensity it may possibly

relationship between maximum tsunami amplitude and duration of signal all available tsunami observations at tide gauges situated along the north american coast were examined to determine if there is any clear relationship between maximum amplitude and signal duration in total 89 historical tsunami recordings generated by 13 major earthquakes between 1952 and 2011 were investigated tidal variations were filtered out of the signal and the duration between the arrival time and the time at which the signals drops and stays below 0 3 m amplitude was computed the processed tsunami time series were evaluated and a linear least squares fit with a 95 confidence interval was examined to compare tsunami durations with maximum tsunami amplitude in the study region the confidence interval is roughly 20 h over the range of maximum tsunami amplitudes in which we are interested this relatively large confidence interval likely results from variations in local resonance effects late arriving reflections and other effects

magnetofossil spike during the paleocene eocene thermal maximum ferromagnetic resonance rock magnetic and electron microscopy evidence from ancora new jersey united states previous workers identified a magnetically anomalous clay layer deposited on the northern united states atlantic coastal plain during the paleocene eocene thermal maximum petm the finding inspired the highly controversial hypothesis that a cometary impact triggered the petm here we present ferromagnetic resonance fmr isothermal and anhysteretic remanent magnetization first order reversal curve and transmission electron microscopy analyses of late paleocene and early eocene sediments in drillcore from ancora new jersey a novel paleogeographic analysis applying a recent paleomagnetic pole from the faeroe islands indicates that new jersey during the initial eocene had a 6 9 degrees lower paleolatitude 27 3 degrees for ancora and a more zonal shoreline trace than in conventional reconstructions our investigations of the petm clay from ancora reveal abundant magnetite nanoparticles bearing signature traits of crystals produced by magnetotactic bacteria this result the first identification of ancient biogenic magnetite using fmr argues that the anomalous magnetic properties of the petm sediments are not produced by an impact they instead reflect environmental changes along the eastern margin of north america during the petm that led to enhanced production and or preservation of magnetofossils

some tsunami characteristics deducible from tide records abstract after an initial 40 hour diffusion period the time decay of tsunami variance was found to be uniformly exponents for 28 events among eight pacific tide stations thew results essentially confirm munk s acoustic deny hypothesis except that the decay e folding time 22 h more nearly equated the ocean s normal mode transit time 21 h than munk s mean collision time 14 h relative tsunami energy obtained by extrapolating exponential decay back to t 0 was found to be similarly ranked among tsunamis at all stations and roughly proportional to seismic energy a total energy estimate for the tsunami of 9 march 1957 obtained by correcting the observed energy decay at wake island for instrument and island response provided normalized total energy estimates for all tsunamis that were consistent with independent estimates by kajiura and by aida similarities between power spectra computed from these time series suggests that station response is primarily linear normal mode forcing of the conti

climate and bioproductivity control on carbonate turbidite sedimentation paleocene to earliest eocene gulf of biscay zumaia spain abstract the paleocene to lowermost eocene zumaia series situated along the basque coast northern spain consists of pelagic limestones and marlstones with interbedded mixed calcarenite turbidites we have compared the composition and frequency of turbidite beds in time as well as the clay mineral and bulk rock carbon isotope composition of the pelagic beds to discern the factors controlling turbidite deposition the pelagic beds are coccolithic mudstones with mainly planktic foraminifera the sources of detrital material to turbidites were the carbonate producing shelves bearing foramol associations around the evolving bay of biscay and to a minor extent the incipient pyrenean chain for siliciclastic components we have found close relationships between variations of turbidite facies and depositional rates with clay mineral assemblages and carbon isotopes in the pelagic beds the latter are in line with global trends it appears that in the early bay of biscay climate and nutrient availability controlled turbidite sedimentation the bulk rock late paleocene np 5 np 9 positive carbon isotope excursion coincides with a period of relatively cool and dry climate characterized by the highest frequency of turbidity flow we propose that during this period globally enhanced latitudinal temperature gradients and strong thermohaline ocean circulation increased bioproductivity in surface waters by upwelling and or by wind driven ekman pumping in contrast warm perennially wet periods such as the early paleocene np 1 np 4 and the paleocene eocene transition upper np 9 np 10 are characterized by low frequency of turbidity flow in the basin this may have been caused by sluggish thermohaline circulation and low carbonate productivity during this time period

comparison of decay features of the 2006 and 2007 kuril island earthquake tsunamis summary characteristics of the tsunami decay processes are examined following the definition and discussion of the major terms involved moving root mean squared amplitude tsunami coda and non dimensional tsunami amplitude nda tsunami waveform data observed at tidal stations in japan during two kuril island earthquake tsunamis in 2006 and 2007 are analysed the tsunami codas of these events showed the following characteristics 1 the decay process determined by the tsunami coda of the 2006 tsunami implies that the decay time constant at a tidal station depends on which ocean the station is facing 2 fluctuations of the ndas in the tsunami codas are stochastically approximated by either the rayleigh distribution or the normal distribution and the distributions of the ndas at most tidal stations are similar 3 differences in the decay processes between these two tsunami events were small with regard to the averaged decay time constants and the distributions of the ndas these findings may be the first step towards improved forecasting of the tsunami decay process

coupled and decoupled responses of continental and marine organic sedimentary systems through the paleocene eocene thermal maximum new jersey margin usa 1 the flux of sediment and organic carbon from continents to the coastal ocean is an important factor governing organic burial in coastal sediments and these systems preserve important records of environmental and biogeochemical conditions during past global change events burial of organic materials in coastal systems can be promoted by chemical resilience or through protection by association with mineral surfaces but the role and influence of these processes on organic records from ancient sediments is poorly known we studied sediment and organic matter burial as particulate organic matter pom and mineral bound organic matter mom in near shore marine sediments from the wilson lake core new jersey usa that span the paleocene eocene thermal maximum petm a climatic perturbation 55 9 myr ago our results show that distinct pom and mom fractions can be isolated from sediments both fractions appear to be dominated by terrestrial material but pom consisted primarily of recently synthesized material whereas mom included a significant fraction of pre aged organic matter from soils or ancient sediments variation in organic burial through the petm is associated with changes in inorganic nitrogen burial clay mineralogy and clastic grain size that we associate with enhanced continental weathering erosion and redeposition of ancient kaolinites and eustatic sea level variation respectively these results provide a new perspective on factors governing carbon burial and carbon isotope records in ancient marine margin settings and offer information on rate and phasing of late paleocene early eocene earth system changes that may constrain interpretations of the cause of the petm climate change event

shallow marine response to global climate change during the paleocene eocene thermal maximum salisbury embayment usa the paleocene eocene thermal maximum petm was an interval of extreme warmth that caused disruption of marine and terrestrial ecosystems on a global scale here we examine the sediments flora and fauna from an expanded section at mattawoman creek billingsley road mcbr in maryland and explore the impact of warming at a nearshore shallow marine 30 100 m water depth site in the salisbury embayment observations indicate that at the onset of the petm the site abruptly shifted from an open marine to prodelta setting with increased terrestrial and fresh water input changes in microfossil biota suggest stratification of the water column and low oxygen bottom water conditions in the earliest eocene formation of authigenic carbonate through microbial diagenesis produced an unusually large bulk carbon isotope shift while the magnitude of the corresponding signal from benthic foraminifera is similar to that at other marine sites this proves that the landward increase in the magnitude of the carbon isotope excursion measured in bulk sediment is not due to a near instantaneous release of 12c enriched co2 we conclude that the mcbr site records nearshore marine response to global climate change that can be used as an analog for modern coastal response to global warming

ostracode turnover and sea level changes associated with the paleocene eocene thermal maximum the ostracode response to oceanographic changes during the paleocene eocene thermal maximum petm ca 55 ma is largely unknown the gebel duwi section egypt provides a detailed ostracode record across the petm in a middle neritic setting quantitative analysis of this record reveals two significant results 1 the petm is marked by a sharp faunal turnover as indicated by abundance changes local extinctions and immigrations this turnover punctuated a gradual basin wide faunal transition 2 during the 60 k y period prior to the petm relative sea level fell rapidly by 15 m this sea level fall was followed by an 20 m sea level rise during the petm a possible eustatic control on these fluctuations suggests the presence of a cryosphere and variations in its size during this time of global warmth

similarities between planktonic and larger foraminiferal evolutionary trends through paleogene paleoceanographic changes abstract the paleogene evolutionary records of planktonic foraminifera and larger benthic foraminifera show parallel patterns in development that may in part reflect changes in nutrient flux to surface waters following the terminal cretaceous extinctions faunas were dominated by a few cosmopolitan opportunistic species more specialized k strategists in both groups diversified during the paleocene dominating into the early eocene consistent with he globally mild climatic regime and probable limited rates of nutrient flux to surface waters high latitude cooling intensified in the middle eocene promoting diversification of less specialized taxa characteristic of cooler and deeper waters higher latitudes meridional upwelling zones and boundary currents geographic ranges of warm water taxa diminished and fragmented yet many species survived thus global diversities during the middle eocene were the highest in the cenozoic as cooling and increased rates of nutrient flux further intensified in the late eocene extinction rates of warm water planktonic and larger benthic species exceeded origination rates of cooler water and less specialized forms so diversity dropped to intermediate levels where it remained through the late eocene and oligocene previous observations that planktonic foraminiferal faunas dominated by warm water taxa are often replaced by cool water faunas even though oxygen isotopes only recorded relatively minor cooling can be reconciled by the explanation that the biotic communities responded to changes in trophic resources and euphotic habitats that accompany the temperature reduction as well as to temperature change itself

palaeoclimatic interpretation of clay minerals in marine deposits an outlook from the continental origin abstract as distribution of clay minerals in modern oceans seems to be controlled by contemporary climates marine clays in ancient deposits have been widely used to reconstruct palaeoclimates in this review we examine this question mainly from the continental origin of the clay minerals and show the difficulties of retrospective analysis of the influence of climate on common marine deposits we examine successively how soils develop and behave are reworked and palaeoweatherings are preserved focusing the review on kaolinitic soils indicative of tropical wet climates several stages intervene between the time of clay mineral development in soils and their final deposition in the basin 1 the persistence over geological times of huge amounts of kaolinitic palaeoweathering materials in the landscapes may seriously alter the palaeoclimatic signal of kaolinite in the sedimentary record although the kaolinite deposited in recent sediments of the world oceans is consistent with wet climatic zones this is mainly because the major kaolinitic and bauxitic palaeosurfaces coincide with the tropical areas where kaolinite is still developing at present 2 possible development of deep kaolinitic profiles at high latitudes and cold conditions under co 2 enriched palaeoatmospheres or even by unusual acidic weathering linked with dry climates is misleading palaeoenvironments for palaeoclimatic reconstruction 3 erosion and transport processes always cloud the signal to some extent because frequently erosion products from the bedrock and different soil horizons will be mixed and major drainage systems may include soils of different climatic zones 4 the arrival of the soil clay assemblages in the basin inevitably lags against their formation on the continent and may occur several million years after formation of the soils on the continent and climate may have considerably changed at that time it is pointed out that sedimentologists and palaeoclimatologists should consider the complexity of the relations between soil and sedimentary clay minerals soil formation rates are slow and therefore the resolution of the palaeoclimatic record in marine clay may not be closer than 1 or 2 ma at present the palaeoclimatic interpretations of marine clay assemblages are yielding at best nothing more than rather broad palaeoclimatic information this approach cannot achieve the same degree of resolution as other techniques such as isotope or microfossil studies clay mineral assemblages may provide integrated records of overall climatic impacts whereas other techniques are more likely to reveal local or temporary climates

paleogene geochronology an integrated approach geochronology is the conceptual division of continuous time as measured geochronometry by the progression in an ordinal series of events this is best achieved by an approach which integrates four independent data sets magnetostratigraphy seafloor spreading magnetic lineation patterns biostratigraphy and isotopic ages this integrated approach results in an ordinal framework which can measure time with greater resolution though perhaps less accuracy than a radiometric approach alone a comparative analysis of two recently proposed paleogene geochronologic time scales is presented

eustatic variations during the paleocene eocene greenhouse world we reconstruct eustatic variations during the latest paleocene and earliest eocene 58 52 ma dinoflagellate cysts grain size fractions and organic biomarkers in marine sections at four sites from three continents indicate an increased distance to the coast during the paleocene eocene thermal maximum petm the same trend is recognized in published records from other sites around the world together the data indicate a eustatic rise during the petm beginning 20 to 200 ka before the globally recorded negative carbon isotope excursion cie at 55 5 ma although correlations are tentative we recognize other global transgressions during chrons c25n and c24n the latter may be associated with eocene thermal maximum 2 53 5 ma or the x event 52 ma these results suggest a link between global sea level and hyperthermal intervals potentially because of the melting of small alpine ice sheets on antarctica thermal expansion of seawater or both however the early onset of sea level rise relative to the cie of the petm suggests contributions from other mechanisms perhaps decreasing ocean basin volume on sea level rise copyright 2008 by the american geophysical union

abrupt deep sea warming palaeoceanographic changes and benthic extinctions at the end of the palaeocene a remarkable oxygen and carbon isotope excursion occurred in antarctic waters near the end of the palaeocene 57 33 myr ago indicating rapid global warming and oceanographic changes that caused one of the largest deep sea benthic extinctions of the past 90 million years in contrast the oceanic plankton were largely unaffected implying a decoupling of the deep and shallow ecosystems the data suggest that for a few thousand years ocean circulation underwent fundamental changes producing a transient state that although brief had long term effects on environmental and biotic evolution

higher temperatures and lower oceanic pco2 a climate enigma at the end of the paleocene epoch one of the largest and most abrupt climatic warming events documented in the geologic record occurred at the end of the paleocene epoch oceanic deep waters warmed to 10 c and high latitude surface waters warmed from 10 c to 20 c within several thousand years this coincided with weakened atmospheric circulation and the extinction of 50 of deep sea benthic foraminiferal species it has been suggested that this warm excursion was forced by higher atmospheric pco2 and greenhouse effects caused by a pulse of hydrothermal activity and or volcanism stable isotopic evidence is presented from two widely separated locations that suggest this warming was associated with a drop in oceanic pco2 rather than an increase oceanic pco2 change across this event was estimated using a model of 13c fractionation in photosynthate organic carbon versus co2aq with solubility constants for co2 and stable isotopic paleotemperature estimates to derive a well preserved record for surface ocean 13c change the organic carbon bound within the calcite lattice of well preserved planktonic foraminifera was extracted for isotopic analysis with allowance for uncertainty in the isotopic differences between phytoplankton and foraminiferal organic matter the initial results indicate a drop in surface ocean pco2 at high and low latitudes from 600 700 parts per million ppm to 200 ppm lower pco2 persisted for at least 10 000 years the duration of the pco2 excursion was long enough for the ocean and atmosphere to have reached a new steady state condition there is no evidence of increased organic carbon burial in the deep sea during this period two alternative explanations are presented to account for such a rapid drop in oceanic pco2 one involves reduced upwelling induced by diminished wind stress as atmospheric circulation weakened in response to climate warming this would have reduced the rate of metabolic co2 recycling into the surface ocean it will be necessary to obtain data from regions outside potential upwelling zones in order to evaluate this the second involves a readjustment of carbonate equilibria in the ocean to higher co3 in the surface ocean particularly at high latitudes where surface waters warmed to approximately 20 c such a shift in carbonate equilibria would have lowered the ocean s capacity to take in co2 if the initial results presented here do accurately reflect a change in the global ocean co2aq the paleocene eocene boundary event may provide clues about the ocean s physical and biological response to rapid large scale perturbations in atmospheric pco2 and to global warming

sea level and salinity fluctuations during the paleocene eocene thermal maximum in arctic spitsbergen palaeoenvironmental manifestations of the palaeocene eocene thermal maximum petm 56 ma are relatively well documented in low to mid latitude settings and at high southern latitudes but no documented high northern latitude sites record the entire hyperthermal event we present high resolution multi proxy records from a petm succession on spitsbergen in the high arctic palaeolatitude 75 n by comparing our results with those from integrated ocean drilling program site 302 4a we document regional palaeoenvironmental variations in the expression of the petm with evidence for major differences in basin margin vegetation and water column oxygen depletion sedimentological palynological and geochemical data demonstrate a pre petm sea level rise in spitsbergen before the delta13ctoc excursion which culminated in maximum flooding during the peak of the event the appearance of the dinoflagellate cyst apectodinium before the onset of the carbon isotope excursion cie corroborates environmental change in the arctic had begun prior to the cie sedimentological and palynological evidence indicate that elevated terrestrial runoff resulted in water column stratification providing further evidence for an intensification of the hydrological cycle during the petm

plant and mammal diversity in the paleocene to early eocene of the bighorn basin abstract abundant plant and vertebrate fossils have been recovered from fluvial sediments deposited in the bighorn basin wyoming during the first 13 m y of the tertiary here we outline and discuss changes in the composition and diversity of floras and faunas during this period which includes the recovery of terrestrial ecosystems from the k t boundary extinctions and later during the paleocene eocene transition the greatest global warming of the cenozoic floral diversity has been studied at three levels of spatial resolution sub local at individual collecting sites local along a single bed or stratigraphic horizon and basin wide regional sub local diversity shows a moderate increase from the early to late paleocene followed by a decrease across the paleocene eocene boundary then an increase into the later early eocene local heterogeneity was lower in paleocene backswamp floras although distinct groups of species dominated in different local fluvial settings such as backswamps and alluvial ridges heterogeneity of backswamp forests increased by about 65 from the early to late wasatchian early eocene the number of plant species inferred from the bighorn basin dataset rose gradually from the puercan to an early clarkforkian peak of about 40 species declined sharply to about 25 species by the clarkforkian wasatchian boundary then rose through the wasatchian to about 50 species a regional analysis of mammalian genera shows high turnover and a rapidly increasing number of genera within a million years of the k t boundary 10 50 genera a slight decline to 40 genera by the early clarkforkian then an increase from 40 to 75 genera by the late wasatchian our analyses found no major extinctions in mammals during the paleocene and early eocene in the bighorn basin but a one third decrease in the number of plant species at about the paleocene eocene boundary rates of taxonomic turnover were much higher for mammals than plants the diversity trends for plants and mammals show little congruence implying that the two groups responded in a very different manner to post k t extinction opportunities there is also little congruence between plant diversity levels and change in mean annual temperature mat as inferred from foliar physiognomy

paleocene eocene thermal maximum environmental change in the new jersey coastal plain benthic foraminiferal biotic events abstract the environmental impact of the paleocene eocene thermal maximum petm has been intensively studied in the new jersey coastal plain but the benthic foraminiferal response reflecting bottom water conditions has not been documented at high resolution we use benthic foraminiferal data across the paleocene eocene boundary in cores from wilson lake wl and bass river br to recognize 5 foraminiferal associations based on species clusters their varying abundances allow the identification of a stratigraphic succession of 8 distinct biofacies across the studied interval uppermost paleocene biofacies 1 corresponds to the glauconitic sands of the vincentown formation and contains rare small planktic foraminifera and a diverse benthic fauna sediments accumulated slowly in a sufficiently oxygenated outer neritic setting depth 100 110 m at wl 140 150 m at br under fairly oligotrophic conditions the embayment was storm dominated and influenced by strong currents inhibiting deposition of suspended fine particles e g planktic foraminifera clay and enhancing re suspension no significant pre petm environmental changes are detected in the benthic foraminiferal assemblages deposition of the fine grained silty clays of the marlboro clay started at the onset of the petm with transitional lithology present at wilson lake gavelinella beccariiformis common at deep shelfal to bathyal abyssal depths is the only taxon to become extinct at this level water depth increased during the petm to a maximum of 130 150 m at wl planktic foraminifera increased strongly in abundance while the benthic foraminiferal assemblage changed to a more opportunistic less diverse assemblage dominated by stress tolerant taxa tappanina selmensis pulsiphonina prima and anomalinoides acutus biofacies 2 increased riverine influence may have reduced vertical mixing initiating stratification of the water column and establishment of a continuously dysoxic mud belt benthic diversity then gradually increased indicating environmental recovery biofacies 3 and 4 40 95 kyr post petm onset riverine influence probably became more variable generating peak abundances of specialized taxa in a mud belt system with increased accumulation rates the latest petm biofacies 5 95 kyr post onset contains a poorly diverse bulimina callahani assemblage indicative of reoxygenated but still eutrophic bottom water conditions with renewed vertical mixing the lower eocene glauconitic sandy clays of the manasquan formation contain an outer neritic benthic fauna biofacies 6 8 depth 100 135 m at wl indicative of persistent high primary production with return of more vigorous currents higher abundances of buliminids may have been triggered by upwelling along frontal zones our environmental interpretations indicate relatively stable benthic foraminiferal ecosystems at persistently outer neritic water depths 100 150 m despite distinct temporary changes during the petm including eustatic sea level rise of up to 30 m and widespread establishment of dysoxic conditions

latest paleocene lithologic and biotic events in neritic deposits of southwestern new jersey in the southwestern new jersey coastal plain four drill holes contain continuous neritic sedimentation across the paleocene eocene boundary calcareous nannofossil zone np 9 np 10 boundary significant lithologic and biotic changes occur in these strata near the top of the paleocene global warming increased precipitation and other oceanographic and climatic events that have been recognized in high latitude deep oceanic deposits of the latest paleocene also influenced mid latitude shallow marine and terrestrial environments of the western north atlantic the diverse well preserved calcareous nannofossil flora that is present throughout the entire new jersey boundary section accurately places these events within the uppermost part of the upper paleocene zone np 9 several rapid but gradational changes occur within a 1 1 m interval near the top of zone np 9 the changes include 1 a change in lithology from glauconitic quartz sand to clay 2 a change in clay mineral suites from illite smectite dominated to kaolinite dominated 3 a change in benthic foraminiferal assemblages to a lower diversity fauna suggestive of low oxygen environments 4 a significant increase in planktonic foraminiferal abundance and 5 an increased species turnover rate in marine calcareous nannofossils pollen was sparse in the new jersey drill holes but terrestrial sporomorph species in virginia exhibit increased turnover rates at a correlative level foraminiferal assemblages and lithology indicate that relative sea level rose in new jersey at the same time as these late paleocene events occurred in late biochron np 9 the higher sea levels influenced sediment type and absolute abundance of planktonic foraminifers in the deposits above the initial increase of kaolinite in the upper part of zone np 9 the kaolinite percentage continues to increase and the maximum kaolinite value occurs in the uppermost part of zone np 9 there are few changes in either the sediments or the biota precisely at the zone np 9 np 10 boundary in new jersey the clay rich deposits with a high kaolinite clay mineral suite the lowered diversity benthic foraminiferal assemblages the abundant planktonic foraminiferal specimens and the calcareous nannofossil assemblages continued essentially unchanged into the earliest eocene zone np 10 within the lower part of zone np 10 the kaolinite percentage decreased to very low values

response of antarctic odp site 690 planktonic foraminifera to the paleocene eocene thermal maximum faunal evidence for ocean climate change 1 high resolution study of antarctic planktonic foraminiferal assemblages ocean drilling program site 690 weddell sea shows that these microplankton underwent a stepwise series of changes during the paleocene eocene thermal maximum petm initiation of this response coincides with the onset of the carbon isotope excursion cie but precedes the benthic foraminiferal mass extinction the top to bottom succession in the biotic response indicates that the surface ocean atmosphere was affected before the deep sea the earliest stage of the faunal response entailed a conspicuous turnover within the shallow dwelling genus acarinina and a succession of stratigraphic first appearances the genus morozovella large 180 m biserial planktonics and a wilcoxensis are all restricted to the lower cie within this petm section acarininid populations crashed as the ocean climate system ameliorated during the cie recovery reflecting atypical surface water conditions this transient decline in acarininids is paralleled by a marked increase in carbonate content of sediments it is postulated that this interval of carbonate enrichment and its unusual microfauna reflects enhanced carbon storage within reservoirs of the global carbon cycle other than the marine carbonate system sensu broecker et al 1993 ravizza et al 2001

changes in the hydrological cycle in tropical east africa during the paleocene eocene thermal maximum the paleocene eocene thermal maximum petm at ca 55 8 ma is one of the most studied instances of past greenhouse gas induced global warming as such it provides a rich opportunity to examine the impact of such global change on local climates the effects of increased continental and sea surface temperatures on local precipitation and humidity during the petm remain poorly constrained and studies reveal complex regional differences whilst some localities appear to experience a net increase in humidity others exhibit the opposite crucially there are few records of hydrological change from tropical regions recent onshore drilling expeditions in tanzania have yielded expanded sedimentary sections deposited in a marine environment that span much of the late cretaceous and paleogene and show exceptionally good preservation of both calcareous microfossils and organic matter the petm interval has previously been constrained by both biostratigraphy and carbon isotopic records and spans ca 7 m of section lipid distributions including various terrestrial marine and bacterial biomarkers and their hydrogen isotopic compositions as well as mineralogy were used to examine east african vegetation and hydrological responses to the global change occurring at the petm although total organic carbon contents decrease the concentrations of both higher plant n alkanes n alkanoic acids and soil bacterial glycerol dialkyl glycerol tetraethers biomarkers increase dramatically at the onset of the petm negative carbon isotope excursion cie suggesting an increased discharge of fluvial sedimentary organic matter similarly mineralogical indicators of terrestrial input including ti al and si al ratios quartz contents and notably the proportion of kaolinite also increase at the onset of the cie however higher plant leaf wax n alkanes c27 c29 and c31 become more deuterium enriched throughout the same interval suggesting a more arid and or hotter rather than a more humid environment this evidence collectively suggests an east african early petm climate characterised by overall hot and arid conditions punctuated by intense perhaps seasonal precipitation events these data match observations from other locations at mid latitudes suggesting that the humid climate often suggested for the petm was not globally widespread

paleocene to eocene benthic foraminiferal isotopes and assemblages implications for deepwater circulation early paleogene warm climates may have been linked to different modes and sources of deepwater formation warm polar temperatures of the paleocene and eocene may have resulted from either increased atmospheric trace gases or increased heat transport through deep and intermediate waters the possibility of increasing ocean heat transport through the production of warm saline deep waters wsdw in the tethyan region has generated considerable interest in addition general circulation model results indicate that deepwater source regions may be highly sensitive to changing basin configurations to decipher deepwater changes we examined detailed benthic foraminiferal faunal and isotopic records of the late paleocene through the early eocene 60 to 50 ma from two critical regions the north atlantic bay of biscay site 401 and the pacific shatsky rise site 577 these records are compared with published data from the southern ocean maud rise site 690 islas orcadas rise site 702 during the late paleocene similar benthic foraminiferal 18o values were recorded at all four sites this indicates uniform deepwater temperatures consistent with a single source of deep water the highest 13c values were recorded in the southern ocean and were 0 5 more positive than those of the pacific we infer that the southern ocean was proximal to a source of nutrient depleted deep water during the late paleocene upper paleocene reflector ab was cut on the western bermuda rise by cyclonically circulating bottom water also suggesting a vigorous source of bottom water in the southern ocean a dramatic negative excursion in both carbon and oxygen isotopes occurred in the latest paleocene in the southern ocean this is a short term 100 kyr globally synchronous event which also is apparent in both the atlantic and pacific records as a carbon isotopic excursion of approximately 1 faunal analyses from the north atlantic and pacific sites indicate that the largest benthic foraminiferal faunal turnover of the cenozoic was synchronous with the isotopic excursion lending support to the hypothesis that the extinctions were caused by a change in deepwater circulation we speculate that the southern ocean deepwater source was reduced or eliminated at the time of the excursion during the early eocene southern ocean 13c values remained enriched relative to the north atlantic and pacific however the southern ocean was also enriched in 18o relative to these basins we interpret that these patterns indicate that although the southern ocean was proximal to a source of cool nutrient depleted water the intermediate to upper deep water sites of the north atlantic and pacific were ventilated by a different source that probably originated in low latitudes i e wsdw

terrestrial records of a regional weathering profile at the paleocene eocene boundary in the williston basin of north dakota the orange zone within the bear den member of the golden valley formation williston basin north dakota represents a terrestrial weathering profile formed by intense pedogenesis during an ancient ca 55 ma global warming event referred to as the paleocene eocene thermal maximum distinctive features of the orange zone include 1 high abundances of kaolinite 2 a strongly leached character with a bright orange iron enriched horizon 3 poor organic carbon preservation and 4 ferric pans pisoliths at its basal contact equivalent to modern lateritic materials though conclusive evidence such as a distinctive paleocene eocene thermal maximum flora and or definitive carbon isotope excursion is lacking the stratigraphic succession of palynofloral datums preserved within the upper part of the bear den orange zone is similar to that associated with the later stages of other terrestrial paleocene eocene thermal maximum records from the u s western interior bulk 13 c org ratios decrease through the orange zone as well but the magnitude of this isotopic decrease is less than that of the carbon isotope excursion thus the collective evidence indicates that the early initial stages of the paleocene eocene thermal maximum are either preserved within the barren condensed interval of the lower orange zone or are missing altogether from the williston basin stratigraphy and that the orange zone likely developed during the later recovery stages of the paleocene eocene thermal maximum the williston basin records generally agree with the tenet that continental weathering intensified during the paleocene eocene thermal maximum moreover these records indicate that the paleohydrology of the basin varied markedly and that sequestration of terrestrial organic carbon was greatly reduced as this transient global warming event unfolded

integrated stratigraphy of the paleocene eocene thermal maximum in the new jersey coastal plain toward understanding the effects of global warming in a shelf environment 1 in the new jersey coastal plain a silty to clayey sedimentary unit the marlboro formation represents deposition during the paleocene eocene thermal maximum petm this interval is remarkably different from the glauconitic sands and silts of the underlying paleocene vincentown and overlying eocene manasquan formation we integrate new and published stable isotope biostratigraphic lithostratigraphic and ecostratigraphic records constructing a detailed time frame for the petm along a depth gradient at core sites clayton wilson lake ancora and bass river updip to downdip the onset of the petm marked by the base of the carbon isotope excursion cie is within the gradual transition from glauconitic silty sands to silty clay and represented fully at the updip sites wilson lake and clayton the cie core interval is expanded at the updip sites but truncated the cie core is complete at the bass river and ancora sites where the early part of the recovery is present most complete at ancora the extent to which the petm is expressed in the sediments is highly variable between sites with a significant unconformity at the base of the overlying lower eocene sediments our regional correlation framework provides an improved age model allowing better understanding of the progression of environmental changes during the petm high resolution benthic foraminiferal data document the change from a sediment starved shelf setting to a tropical river dominated mud belt system during the petm probably due to intensification of the hydrologic cycle the excellent preservation of foraminifera during the petm and the lack of severe benthic extinction suggest there was no extreme ocean acidification in shelf settings

correlation between isotope records in marine and continental carbon reservoirs near the palaeocene eocene boundary changes in the isotope content of the large marine carbon reservoir can force shifts in that of the smaller carbon pools in the atmosphere and on land the carbon isotope compositions of marine carbonate sediments from the late palaeocene vary considerably exhibiting a sudden decrease close to the palaeocene eocene boundary which coincides with deep sea benthic extinctions1 and with changes in ocean circulation here we report that these fluctuations in the marine carbon isotope record are closely tracked by the terrestrial records provided by palaeosol carbonates and mammalian tooth enamel in using palaeosol carbonates to reconstruct the co2 content of the ancient atmosphere2 isotope shifts of this sort will have to be taken into account the sharp decrease in 13c 12c ratios in the late palaeocene provides a datum for precise correlation of marine and continental records and suggests that abrupt climate warming at this time may have played an important role in the evolution of land mammals

paleogene paleosols and changes in pedogenesis during the initial eocene thermal maximum big bend national park texas usa this paper tests the hypothesis that continental chemical weathering increased during the initial eocene thermal maximum ietm by comparing paleosols that formed before and during the event in western texas the chemical index of alteration cia was used to investigate the weathering of silicate minerals paleosols generated before the ietm have cia values ranging from 62 to 72 and cia values during the ietm range from 67 to 82 the cia values for pre initial eocene thermal maximum paleosols indicate moderate weathering conditions and cia values during the event indicate moderate to extreme weathering conditions the clay mineralogy of the paleosols is dominated by smectite and it is only within paleosols that formed during the ietm that there is a change there is a notable increase in the amount of kaolinite in one paleosol horizon that is associated with the carbon excursion in addition there is an increase in the translocation of clays and iron and an increase in the leaching of calcite and plagioclase in initial eocene thermal maximum paleosols the differences between soils that formed before and during the initial eocene thermal maximum indicate that chemical weathering did increase during this ancient global warming event the mechanism responsible for increased weathering is interpreted to be an increase in hydrolysis reactions caused by an increase in humidity and an increase of carbonic acid in the soil due to elevated co2 levels during the initial eocene thermal maximum documentation of an increase in chemical weathering during the initial eocene thermal maximum is significant because it may have served as a negative feedback to reduce atmospheric co2

sea level humidity and land erosion records across the initial eocene thermal maximum from a continental marine transect in northern spain in two continental sections in the tremp basin northern spain the initial eocene thermal maximum also known as the paleocene eocene thermal maximum is registered by an 6 fall in 1 3 c values in soil carbonate nodules high resolution correlations using the 1 3 c excursion can be made to nearby shelf and bathyal marine settings allowing a detailed reconstruction of soil formation on land and transport of detritus to the sea during the initial eocene thermal maximum soils that formed before and after the initial eocene thermal maximum in the tremp region reflect arid to semiarid conditions with abundant evaporative minerals whereas initial eocene thermal maximum soils reflect seasonally wetter but generally dry conditions during the initial eocene thermal maximum land erosion was intensified and accumulation rates of terrigenous detritus in the sea increased this reflects both increased topographic relief associated with a prominent sea level lowstand and enhanced seasonal precipitation over a dry landscape with sparse vegetation deeper erosion led to an increase in the flux of kaolinite from buried mesozoic soils to the oceans the association of the initial eocene thermal maximum with a sea level lowstand in northern spain as well as at other marginal north atlantic sites may reflect coeval large scale magmatic activity in the northernmost atlantic

palaeocene eocene paratropical floral change in north america responses to climate change and plant immigration the initial eocene thermal maximum ietm at c 55 ma represents a period of rapid global warming that lasted less than 200 ka the response of vegetation to such an event and particularly warm adapted highly diverse vegetation types is poorly understood using pollen floral clay mineral and stable carbon isotope analyses of sediments from the upper tuscahoma formation on the eastern us gulf coast eastern mississippi and western alabama we document paratropical floral changes across the palaeocene eocene boundary from the wahalak 2 and lower harrell cores data indicate strong changes in the abundance of kaolinite that correlate with changes in relative abundance of native pollen taxa there is no evidence for a transient extra tropical flora on the us gulf coast that may characterize the ietm immigration and extinction are not associated with this event instead early eocene plant immigration occurs in pulses and therefore is not associated directly with climate change during the ietm the two cores share the same regional species pool but compositional differences are stronger between cores than they are either through changes in environment increased soil erosion or chemical weathering or through the introduction of non native plants our data suggest that vegetation change across the palaeocene eocene boundary is not a single event but rather a sequence of cascading events

stratigraphic and climatic implications of clay mineral changes around the paleocene eocene boundary of the northeastern us margin abstract kaolinite usually is present in relatively small amounts in most upper paleocene and lower eocene neritic deposits of the northern us atlantic coastal plain however there is a short period less than 200 000 k y in the latest paleocene upper part of calcareous nannoplankton zone np 9 when kaolinite dominated clay mineral suites replaced the usual illite smectite dominated suites during this time of global biotic and lithologic changes kaolinite increased from less than 5 of the clay mineral suite to peak proportions of 50 60 of the suite and then returned to less than 5 in uppermost paleocene lowermost eocene strata this kaolinite pulse is present at numerous localities from southern virginia to new jersey these sites represent both inner and middle neritic depositional environments and reflect input from several river drainage systems thus it is inferred that kaolinite rich source areas were widespread in the northeastern us during the latest paleocene erosion of these source areas contributed the kaolinite that was transported and widely dispersed into shelf environments of the salisbury embayment the kaolinite increase which occurred during a time of relatively high sea level probably is the result of intensified weathering due to increased temperature and precipitation the southern extent of the kaolinite pulse is uncertain in that uppermost paleocene beds have not been identified in the southern atlantic coastal plain the late paleocene kaolinite pulse that consists of an increase to peak kaolinite levels followed by a decrease can be used for detailed correlation between more upbasin and more downbasin sections in the salisbury embayment correlations show that more upbasin paleocene eocene boundary sections are erosionally truncated they have varying portions of the kaolinite increase and if present at all discontinuous portions of the subsequent kaolinite decrease as these truncated sections are disconformably overlain by lower eocene strata rapid erosional removal of large parts of the most kaolinite rich p e boundary clay deposits occurred by early eocene time erosion of the kaolinite rich p e boundary beds was enhanced during times of sea level fall when kaolinite rich sediments were redeposited to produce kaolinite spikes in basal beds of lower and middle eocene sequences that have little or no kaolinite elsewhere in the sequence in contrast more downbasin sites document only the upper decreasing part of the kaolinite pulse the absence of strata documenting the earlier kaolinite increase is attributed to slow sedimentation condensed interval as a result of a significant sea level rise that ponded most sediments in shallower waters combined with the probable subsequent erosional removal of these thin downbasin deposits by oceanic currents

climate model and proxy data constraints on ocean warming across the paleocene eocene thermal maximum article constraining the greenhouse gas forcing climatic warming and estimates of climate sensitivity across ancient large transient warming events is a major challenge to the palaeoclimate research community here we provide a new compilation and synthesis of the available marine proxy temperature data across the largest of these hyperthermals the paleocene eocene thermal maximum petm this includes the application of consistent temperature calibrations to all data including the most recent set of calibrations for archaeal lipid derived palaeothermometry this compilation provides the basis for an informed discussion of the likely range of petm warming the biases present in the existing record and an initial assessment of the geographical pattern of petm ocean warming to aid interpretation of the geographic variability of the proxy derived estimates of petm warming we present a comparison of this data with the patterns of warming produced by high pco2 sim ulations of eocene climates using the hadley centre atmosphere ocean general circulation model aogcm hadcm3l on the basis of this comparison and taking into account the patterns of intermediate water warming we estimate that the global mean surface temperature anomaly for the petm is within the range of 4 to 5 c

the extraterrestrial impact evidence at the palaeocene eocene boundary and sequence of environmental change on the continental shelf we have identified clear evidence of an extraterrestrial impact within the onset of the carbon isotope excursion cie that defines the palaeocene eocene p e boundary hyperthermal event approx 56 ma from several sites on the eastern atlantic coastal plain and offshore we review and update the state of the evidence for an impact at the p e boundary including a k ar cooling age of the ejecta that is indistinguishable from the depositional age at the p e which establishes the ejecta horizon as an isochronous stratigraphic indicator at the p e immediately above the ejecta peak at the base of the coastal plain marlboro clay unit we identify a sharp increase in charcoal abundance coincident with the previously observed dramatic increase in magnetic nanoparticles of soil pyrogenic origin we therefore revisit the observed sequence of events through the p e boundary on the western atlantic coastal plain showing that an extraterrestrial impact led to wildfires landscape denudation and deposition of the thick marlboro clay whose base coincides with the spherule horizon and cie onset the sr ca ratio of the spherules indicates that the carbon responsible for the onset may be vaporized caco 3 target rock mixed with isotopically light carbon from the impactor or elsewhere crucially we do not argue that the impact was responsible for the full manifestation of the cie observed globally onset to recovery approx 170 kyr rather that a rapid onset was triggered by the impact and followed by additional carbon from other processes such as the eruption of the north atlantic igneous province such a scenario agrees well with recent modelling work though it should be revisited more explicitly this article is part of a discussion meeting issue hyperthermals rapid and extreme global warming in our geological past

integrated stratigraphic studies of paleocene lowermost eocene sequences new jersey coastal plain evidence for glacioeustatic control 1 we describe seven paleocene to lowermost eocene sequences in core holes at island beach bass river ancora millville and sea girt nj ocean drilling program leg 150x 174ax and analyze benthic foraminiferal assemblages to assess paleodepth changes within sequences these sequences are referred to as pa0 pa1a pa1b pa2a pa2b pa3a and pa3b paleocene sequence boundaries are identified by unconformities and variations in benthic foraminiferal biofacies we used q mode factor analysis and paleoslope modeling to identify three distinct middle outer neritic benthic foraminiferal assemblages and their associated water depths paleodepths during the early paleocene and deposition of pa0 pa1a and pa2b were 80 m with 20 m changes across sequence boundaries a long term shallowing occurred through the late paleocene where paleodepths were 50 70 m in pa3a this trend drastically changes in the earliest eocene where the paleodepths of sequence pa3b were 120 150 m new jersey paleocene sequence boundaries correlate with those in other regions and with 18o increases in the deep sea suggesting paleocene eustatic lowerings were associated with ice growth events

planktonic benthonic foraminiferal ratios modern patterns and tertiary applicability abstract the abundance of planktonic specimens in foraminiferal assemblages was determined in numerous bottom samples from inner neritic to deep oceanic depths along the atlantic margin of the northeastern united states the results augment previous studies in other areas that have shown a general increase in percentage of planktonic specimens in total foraminiferal bottom assemblages as water depth increases the patterns found in this area of complex shelf bathymetry and hydrography illustrate the influence on the planktonic benthonic percentages of water depth distance from shore different water mass properties and downslope movement of tests in high energy areas the patterns found in the 661 samples from the atlantic margin were compared with results from 795 stations in the gulf of mexico pacific ocean and red sea the relative abundance of planktonic specimens and water depth correlates positively in all open oceanic areas even though taxonomic composition and diversity of the faunas from different areas is variable the variation of planktonic percentages in bottom samples within most depth intervals is large so that a precise depth determination cannot be made for any given value however an approximate upper depth limit for given percentages can be estimated for open ocean environments a decrease in planktonic percentages is seen in the lower salinity and higher turbidity coastal waters of the gulf of maine planktonic percentages intermediate between the lower values in the less saline coastal waters and the higher values in the normal open oceanic conditions occur in the transitional area between the gulf of maine and the open marine atlantic ocean to the east similarly lowered values in another area of restricted oceanic circulation occur in the high salinity clear but nutrient poor waters of the gulf of aqaba off the red sea a comparison of the similarity of modern planktonic percentage values to those found in earlier tertiary assemblages was made to confirm the usefulness of this measure in the fossil record in some stratigraphic sections in upper paleocene and lower eocene strata of the eastern gulf coastal plain water depths inferred from trends and values of planktonic percentages consistently match paleobathymetry constructed from physical stratigraphic characteristics and paleogeographic relationships

condensation of volatile elements in high temperature gases of mount st helens abstract the cooling of high temperature 675 650 c volcanic gases in silica tubes produces successive condensation of volatile elements as solids on the inner walls of the tubes the chemistry of the solid phases obtained by these reactions varies along the temperature gradient 675 400 c fe3o4 and sio2 occur above 570 c mos2 and fewo4 are mainly enriched between 570 and 480 c nacl and kcl occur in the range 550 450 c and cds occurs at 520 450 c pb and bi sulfides are typical of the low temperature zone 480 400 c thermodynamic calculations performed to define the nature of the stable solid phases in equilibrium with the oxygen sulfur and chlorine fugacities of the gas phase show that the observed solid phases reflect a formation in a low o2 fugacity environment the chemistry of fumarolic incrustations collected around high temperature vents 300 c 5 15 cm below the surface reveals that condensation processes similar to those observed in the tubes occur naturally in the ground these incrustations show marked differences with those generally collected at the outlet of fumarolic vents where reactions with atmospheric gases and wall rocks are the major processes leading to the formation of these incrustations

climatic evolution on the southeastern margin of the tethys negev israel from the palaeocene to the early eocene focus on the late palaeocene thermal maximum during the early palaeocene zones p1 to p2 the southeastern tethyan margin experienced a warm and humid climate with high rainfall as indicated by the abundance of kaolinite within marine sedimentary rocks subsequently in zone p2 arid climatic conditions evolved in the coastal basins of the southern tethys margin as indicated by the gradual disappearance of kaolinite and the increased abundance of palygorskite and sepiolite arid climatic conditions persisted during the selandian and thanetian late palaeocene and reached a maximum in the ypresian early eocene during the late palaeocene thermal maximum warm climatic conditions were associated with increased aridity and led to sea surface warming though not bottom water warming as suggested by the planktic 18 o excursion observed at the zomet telalim basin negev israel strongly reduced surface productivity accompanied by unusually light 13 c are associated with the late palaeocene thermal maximum in the negev as well as globally

environmental impact of volcanic margin formation late rift stage uplift and subsequent massive transient volcanism during breakup of rifted volcanic continental margins constrain paleoenvironments by modifying basin geometry and the composition of the atmosphere hydrosphere and thus biosphere on regional and global scales the early tertiary north atlantic breakup history shows that lava emplacement was accompanied by regional ashfalls and that extrusive complexes influenced paleogene oceanic and continental margin circulation and sedimentation temporal correspondence with the terminal paleocene deep sea extinction event and the earliest eocene greenhouse suggests a global impact possibly by enhanced atmospheric co 2 levels leading to polar warming and thereby changing patterns of deep water formation in this context transient subaerial volcanism at continental margins should be considered with the much discussed continental flood basalt provinces and oceanic plateaus

us gulf coast vegetation dynamics during the latest palaeocene abstract pollen and spore floras from the bear creek section in western alabama us gulf coast record vegetation events from the lower to middle tuscahoma formation late palaeocene mid np9 sporomorphs are abundant and well preserved in these sediments and are used as a proxy to record vegetation change over time we present results from both palynofloral and clay mineral analyses in the interval approximately 0 4 0 1 my before the paleocene eocene thermal maximum petm a period of transient and intense global warming that had a profound effect on animal and plant groups in high latitudes an important factor that has a significant bearing on our understanding of turnover across the petm is that of climate environmental stability prior to the petm in terrestrial ecosystems palynological analysis with a between sample resolution of 4 10 5 yr clay mineral suites show the dominance of smectite and illite throughout the studied section with minor fluctuations in the abundance of kaolinite ranging from 2 to 10 that indicates a high seasonality of precipitation throughout our studied section the exact stratigraphic position of the petm is unknown on the us gulf coast but data from existing publications suggests there is little change in the vegetation type across the palaeocene eocene boundary with no major immigration or turnover events dinocysts are restricted in both diversity and occurrence but apectodinium homomorphum is present with 30 abundance throughout the studied section and provides some evidence that the apectodinium acme is not correlative with the petm at middle latitudes

mesozoic calcareous nannofossil evolution relation to paleoceanographic events the taxonomic evolution of jurassic and cretaceous calcareous nannofossil species is described using the following indices species diversity rate of speciation rate of extinction rate of diversification rate of turnover survivorship and species accretion the jurassic prior to the late oxfordian is characterized by positive diversification rates that is rates of speciation exceeded rates of extinction highest rates of diversification occurred in the late lias and early oxfordian during the generally regressive latest jurassic diversification rates remained low and rates of extinctions exceed rates of speciation in the early cretaceous rates of diversification are positive and peak in the early valanginian early aptian and middle albian after which time rates of extinction generally exceed rates of speciation such peaks in rate of evolution coincide with times of increased accumulation of organic carbon in the ocean anoxic events peaks in rates of extinction result in very high rates of turnover during times of major regressions in particular in the tithonian and maastrichtian survivorship analyses for three datum planes 74 5 144 and 160 ma show relatively constant extinction rates with some stepping in the older part they are best explained by a temporally fluctuating abiotic environment causing changes in the probability of extinction species accretion curves are also relatively linear with some indication of changing rates of speciation the coincidences of major changes in evolutionary rates with major paleoceanographic events are indicative of a predominantly abiotic control of nannoplankton evolution relationships of evolutionary rates of calcareous nannoplankton with deep ocean ventilation sea level and ocean fertility indicates that global tectonic processes are the ultimate causes of evolutionary change

evidence of surface water oligotrophy during the paleocene eocene thermal maximum nannofossil assemblage data from ocean drilling program site 690 maud rise weddell sea 1 nannoplankton assemblages at ocean drilling program site 690 maud rise weddell sea experienced an abrupt and dramatic transformation at the onset of the paleocene eocene thermal maximum petm at 55 m y the major assemblage shift suggests a change from colder more productive surface waters to warmer more oligotrophic conditions significant restructuring of assemblages during the later part of the petm indicates that nannoplankton communities were not stable and that surface water conditions changed although they remained warm and oligotrophic combined with benthic foraminiferal assemblage data nannoplankton assemblage results suggest increased sequestration of nutrients in shelf environments and starvation of the open ocean although the petm was a short lived event it appears to have had long term effects on nannoplankton leading to the extinction of fasciculithus a dominant paleocene genus

the paleocene eocene thermal maximum petm in shallow marine successions of the adriatic carbonate platform sw slovenia the paleocene eocene thermal maximum represents one of the most rapid and extreme warming events in the cenozoic shallow water stratigraphic sections from the adriatic carbonate platform offer a rare opportunity to learn about the nature of paleocene eocene thermal maximum and the effects on shallow water ecosystems we use carbon and oxygen isotope stratigraphy in conjunction with detailed larger benthic foraminiferal biostratigraphy to establish a high resolution paleoclimatic record for the paleocene eocene thermal maximum a prominent negative excursion in 13 c curves of bulk rock 1 3 matrix 4 and foraminifera 6 is interpreted as the carbon isotope excursion during the paleocene eocene thermal maximum the strongly 13 c depleted 13 c record of our shallow marine carbonates compared to open marine records could result from organic matter oxidation suggesting intensified weathering runoff and organic matter flux the ilerdian larger benthic foraminiferal turnover is documented in detail based on high resolution correlation with the carbon isotopic excursion the turnover is described as a two step process with the first step early ilerdian marked by a rapid diversification of small alveolinids and nummulitids with weak adult dimorphism possibly as adaptations to fluctuating paleocene eocene thermal maximum nutrient levels and a second step middle ilerdian characterized by a further specific diversification increase of shell size and well developed adult dimorphism within an evolutionary scheme controlled by long term biological processes we argue that high seawater temperatures could have stimulated the early ilerdian rapid specific diversification together these data help elucidate the effects of global warming and associated feedbacks in shallow water ecosystems and by inference could serve as an assessment analog for future changes

a new zealand record of sea level rise and environmental change during the paleocene eocene thermal maximum abstract the global warming associated with the paleocene eocene thermal maximum petm ca 55 5 myr ago is the most dramatic identified short term temperature increase of the cenozoic one direct consequence of a warming world is a rise in sea level due primarily to the thermal expansion of water as oceans warmed the kumara 2 core south island new zealand spans the paleocene eocene transition and provides a rare southern hemisphere continental margin record of the petm lithology palynology and compound specific stable isotope compositions of higher plant leaf wax n alkanes reveal a 4 85 m petm and a carbon isotope excursion cie of ca 4 5 larger than the 2 5 to 3 5 cies generally recorded by deep sea foraminifera there is a shift from a terrestrial to a marine potentially anoxic sedimentary depositional environment at the base of the petm interpreted as being the result of a local sea level rise coincident with the onset of the cie is the appearance of pollen associated with thermophilic conditions and the development of nypa mangrove swamps moreover there is a reorganisation of the angiosperm pollen assemblage during the petm and an initial increase in fern spores and decrease in gymnosperms crucially all of these changes occur below the horizon characterised by the most negative 13c values suggesting that 1 the recorded negative excursion of 4 5 may indeed reflect the shift in atmospheric co2 isotopic composition and 2 that the large input of 13c depleted carbon into the ocean atmosphere system was not geologically instantaneous with at least some of the added carbon lagging warming sea level rise and vegetation change furthermore compound specific hydrogen isotope analyses show a large degree of variability both directly before and during the cie suggesting that the petm in new zealand was characterised by complex and transient changes in the hydrological regime similar to those reported in north america the arctic and eastern africa thus the new petm record from kumara 2 reveals local climatic and biotic responses driven by a combination of global warming and the consequential change in local depositional environment induced by sea level rise

planktonic and benthic foraminiferal extinction events during the last 100 m y abstract five major planktonic and benthic foraminiferal extinction events occurred during the past 100 m y at the cenomanian turonian c t boundary at the cretaceous tertiary k t boundary in the latest paleocene in the late eocene and in the early middle miocene to clarify the character of the five events i estimated 1 paleo waterdepths and paleoenvironments where foraminifera were affected 2 the duration of each extinction event and 3 evaluated possible causes for each extinction event on the basis of recent literature these extinction events can be classified into three fundamentally different types 1 the mass extinction event at the k t boundary was abrupt and concentrated among surface dwelling species 2 extinctions at the c t boundary and during the latest paleocene were abrupt and mainly affected intermediate and deep water taxa over short periods 3 the late eocene and early middle miocene events affected surface and deep water species and involved stepwise or gradual extinctions over a long period 4 m y i attributed the extinction events to 1 a bolide impact for the k t event 2 a decrease in dissolved oxygen in intermediate and deep waters due to climatic warming for the c t and latest paleocene events and 3 long term global cooling for the late eocene and early middle miocene events the following relationships exist between the causes and types of extinction events 1 large extraterrestrial impacts strongly affected surface dwelling organisms in short term extinction events 2 intermediate and deep water low oxygen conditions induced by climatic warming have severely affected intermediate and deep water organisms over medium and short terms

global change at the paleocene eocene boundary climatic and evolutionary consequences of tectonic events rea d k zachos j c owen r m and gingerich p d 1990 global change at the paleocene eocene boundary climatic and evolutionary consequences of tectonic events palaeogeogr palaeoclimatol palaeoecol 79 117 128 events of the paleocene eocene boundary provide the clearest example to date of how a tectonic event may have global climatic consequences recent advances permit well constrained stratigraphic determination of several events that occurred at that boundary in chron c24r a many fold increase in sea floor hydrothermal activity a global warming a reduction in the intensity of atmospheric circulation a conversion to salinity driven deep ocean circulation a marked lightening of oceanic 313c values extinction and evolution of both benthic foraminifera and land mammals and important plate boundary reorganizations including the outpouring of the east greenland volcanics and the initiation of the oceanic rift between norway and greenland we hypothesize that enhanced sea floor hydrothermal activity occasioned by global tectonism resulted in a flooding of the atmosphere with coz causing a reduced pole to equator temperature gradient and increased evaporation at low latitudes increased formation of warm salty probably low nutrient waters coupled with the warm temperatures at high latitudes occasioned a salinity driven rather than temperature driven deep water circulation this newly evolved ocean circulation pattern changed the apportionment of global heat transport from the atmosphere to the ocean with concomitant changes in the circulation intensity of both reduced intensity of atmospheric circulation resulted in lower oceanic biological productivity and enhanced seasonality of climate on the continents a major extinction event among benthic foraminifera was probably a response to the new low nutrient and chemically changed bottom waters and endemism following rapid evolution and dispersal of mammalian orders may have been in response to the new continental climate regime

the planktonic foraminiferal response to the paleocene eocene thermal maximum on the atlantic coastal plain abstract planktonic foraminiferal assemblages in two cores from maryland and new jersey show evidence for significant changes in surface ocean habitats on the continental shelf during the paleocene eocene thermal maximum petm at both sites significant assemblage shifts occur immediately before the onset of the event these changes include the appearance of abundant triserial biserial species as well as rare excursion taxa which are limited to the interval of the carbon isotope excursion at deep sea sites the assemblage shifts signal the development of new habitats immediately prior to the onset of the petm likely involving warming surface ocean acidification increased stratification and oligotrophy a sharp increase in diversity at the onset of the event is interpreted as a further increase in stratification and warming as well as increased water depth and more eutrophic conditions finally we observe variant morphologies of several planktonic foraminifera which may also signal the response of the assemblage to environmental perturbation

an osmium isotope excursion associated with the late paleocene thermal maximum evidence of intensified chemical weathering in the latest paleocene an abrupt shift to more negative 13c values has been documented at numerous marine and terrestrial sites bralower et al 1997 cramer et al 1999 kaiho et al 1996 kennett and stott 1991 koch et al 1992 stott et al 1996 thomas and shackleton 1996 zachos et al 1993 this carbon isotope event cie is coincident with oxygen isotope data that indicate warming of surface waters at high latitudes of nearly 4 6 c kennett and stott 1991 and more moderate warming in the subtropics thomas et al 1999 here we report 187os 188os isotope records from the north atlantic and indian oceans which demonstrate a 10 increase in the 187os 188os ratio of seawater coincident with the late paleocene cie this excursion to higher 187os 188os ratios is consistent with a global increase in weathering rates the inference of increased chemical weathering during this interval of unusual warmth is significant because it provides empirical evidence supporting the operation of a feedback between chemical weathering rates and warm global climate which acts to stabilize earth s climate walker et al 1981 estimates of the duration of late paleocene cie bains et al 1999 bralower et al 1997 norris and rohl 1999 rohl et al 2000 in conjunction with the os isotope data imply that intensified chemical weathering in response to warm humid climates can occur on timescales of 104 105 years this interpretation requires that the late paleocene thermal maximum os isotope excursion be produced mainly by increased os flux to the ocean rather than a transient excursion to higher 187os 188os ratios in river runoff although we argue that the former is more likely than the latter we cannot rule out significant changes in the 187os 188os ratio of rivers

magnetostratigraphic re calibration of the paleocene eocene boundary interval in holes 550 and 549 goban spur eastern north atlantic a magnetostratigraphic reinvestigation of the paleocene eocene boundary intervals in dsdp holes 550 and 549 goban spur has removed uncertainties associated with the previously published magnetostratigraphic information for these chronostratigraphically important sections in hole 550 levels assigned to nannoplankton zones np4 and 5 previously considered to be of normal polarity carry a reverse polarity characteristic magnetisation which is correlated with geomagnetic chron c26r unconformably overlying these levels is a thin interval of reversely magnetised sediment which records the latter part of chron c25r chron c25n is redefined and its lower upper boundaries are placed respectively at 425 08 and 422 12 mbsf in hole 550 chron c24r extends upwards62 4 m respectively the start and end of chron c24n 3n are placed at 359 69 and 349 41 mbsf in this hole within core 28 just above c24n 3n is a record of chron c24n 2n as well as interval of indeterminate polarity within c24n 2r the problematic issue of assigning numerical ages to the various events associated with the paleocene eocene transition in hole 550 is then discussed the remanence in hole 549 is difficult to interpret because magnetic inclinations in the interval previously assigned to chrons c25n and c24r are typically 20o compared with the60o expected for the paleogene sediments at this site acknowledging the complexities of this record we have constructed the magnetostratigraphy for this hole based on results from the present study and previous work h a townsend the paleomagnetism of sediments acquired from the goban spur on the deep sea drilling project leg 80 in p c de graciansky c w poag et al eds initial reports dsdp 80 1985 389 410 contrary to the previous study we are not able to fix the base of chron c25n it is located either in the lower part of core 18 where the core pieces are too small to be used reliably for paleomagnetic studies or in the gap between cores 18 and 19 the chron c25n 24r boundary is blurred 351 to 353 mbsf because of the shallow inclination problem chron c24n 3n which is characterised by inclinations of35o has its lower upper boundaries at318 and 307 62 mbsf respectively an apparent record of chron c24n 2n based on two samples is present between 305 53 and 304 65 mbsf 1998 elsevier science b v all rights reserved

real time forecasting of the april 11 2012 sumatra tsunami the april 11 2012 magnitude 8 6 earthquake off the northern coast of sumatra generated a tsunami that was recorded at sea level stations as far as 4800 km from the epicenter and at four ocean bottom pressure sensors darts in the indian ocean the governments of india indonesia sri lanka thailand and maldives issued tsunami warnings for their coastlines the united states pacific tsunami warning center ptwc issued an indian ocean wide tsunami watch bulletin in its role as an interim service provider for the region using an experimental real time tsunami forecast model rift ptwc produced a series of tsunami forecasts during the event that were based on rapidly derived earthquake parameters including initial location and mwp magnitude estimates and the w phase centroid moment tensor solutions w phase cmts obtained at ptwc and at the u s geological survey usgs we discuss the real time forecast methodology and how successive real time tsunami forecasts using the latest w phase cmt solutions improved the accuracy of the forecast

benthic foraminiferal assemblages between two major extinction events the paleocene el kef section tunisia abstract the development of benthic foraminiferal assemblages from the paleocene outcrops of the el haria formation near el kef tunisia is discussed qualitatively and quantitatively the aim of the study is to reconstruct the paleoenvironmental evolution between the k pg boundary interval and the late paleocene event and to compare this evolution with results from other sites along the southern tethyan margin eighty four samples covering virtually the entire paleocene provide a dataset that allows detailed qualitative and multivariate analysis the benthic foraminiferal faunas indicate a complex pattern of environmental changes during the paleocene marked by the succession of different benthic associations following the k pg boundary event community restoration was characterized by the gradual build up of faunal diversity decreasing dominance and the entry of taxa common to normal marine outer neritic to upper bathyal environments indicate the completion of the ecosystem restoration in zone plb a highly diverse benthic foraminiferal assemblage persisted throughout the remainder of the early paleocene into the earliest late paleocene at the p3a p3b zonal transition relative sea level lowering is evidenced by the sudden disappearance or decreasing abundance of deeper water taxa e g anomalinoides affinis a susanaensis gavelinella beccariiformis neritic deposition continued into zone p4 when trophic levels at the seafloor increased as indicated by the entry and increasing dominance of species such as anomalinoides cf aegyptiacus bulimina midwayensis and b strobila which we consider to be sensitive to eutrophication the combined effect of shallowing and the subsequent eutrophication led to the establishment of assemblages similar to late paleocene benthic foraminiferal assemblages from egyptian sections some of which record the latest paleocene extinction event these assemblages were interpreted to be indicative of a middle neritic highly eutrophic environment enhanced vertical fluxes of organic matter along the southern tethyan margin may have resulted from intensified upwelling this eventually led to oxygen deficiency at the seafloor it appears that oxygen deficient high productivity shelves were a common feature of the southern tethyan margin during the latest paleocene

problems in chronostratigraphy stages series unit and boundary stratotypes global stratotype section and point and tarnished golden spikes abstract stratigraphy is a magnificent subject magnificent in its breadth and scope magnificent in its importance to so many lines of human endeavor it is essentially that branch of geology which deals with the arrangement the distribution and the chronological succession of rock strata and other associated rock bodies with respect to any or all of the various characters properties and attributes which rocks may possess hedberg 1958 p 1881 chronostratigraphy the temporal ordering of geologic strata is at the heart of earth history in reviewing chronostratigraphic theory from d orbigny to hedberg we see that concepts and practices have evolved under pressure of constant improvements in time control and data quality such stimuli are naturally felt more strongly in the youngest part of the stratigraphic record where dating is most precise and the biostratigraphic data are most abundant and well preserved it is not surprising therefore to find that chronostratigraphy is conceptually more advanced in the cenozoic erathem than in the mesozoic and paleozoic erathems where biostratigraphy and chronostratigraphy are widely confused evidently out of necessity taking the five inter series boundaries in the cenozoic erathem as case histories we review their current status in relation to the lower boundary of the lowest standard stage above the boundary in light of the hierarchical principle recommended in the international stratigraphic guide hedberg 1976 salvador 1994 in each instance what should be a simple nested relationship turns out to be complex and difficult and in the cases of the proposed global stratotype section and point gssps for the eocene oligocene series boundary and the paleocene eocene series boundary there are discrepancies so large with regard to the base of the rupelian and ypresian standard stages respectively that some essential relaxation of the hierarchic rule seems to be required if the historic value of these long known stages is not to be violated since stage boundaries should not be defined a posteriori to fit series boundaries we propose here to reconsider the role of the standard stage as the obligate elemental subdivision in a rigidly hierarchical chronostratigraphic scale and suggest that series and subseries should be formalized and their boundaries defined by gssps we do not suggest that stages be abandoned on the contrary we propose to integrate them in a two step hierarchical chronostratigraphic framework so as to use them in complementary fashion with series and subseries however the boundary concept is more appropriate for stage than the gssp we recognize the need for precise and globally valid chronostratigraphic correlations based on gssps in attempts to understand the earth system while at the same time we emphasize the need for conceptual continuity with regard to the central place that the stage has played in chronostratigraphy over several decades

stratigraphy of late palaeocene events in the middle east implications for low to middle latitude successions and correlations we have investigated the upper palaeocene stratigraphical record in four sections in egypt and one in israel the sections are arranged on a depth transect across the southern tethyan margin in all sections a 13 c excursion and benthic foraminiferal extinctions coincide at a level within planktic foraminiferal zone p5 in three sections a bed sapropelic in two of the deeper profiles contains extraordinarily transient benthic and planktic foraminifera assemblages these planktic assemblages are dominated by acarinina and contain rare to common morozovella allisonensis and globanomalina luxorensis but unusually few other morozovella the extremely restricted stratigraphical range of m allisonensis to the lower part of the 13 c excursion enables 1 a three fold subdivision of zone p5 2 accurate correlation to the best sections spanning the 13 c excursion in the atlantic and pacific and 3 assessment of stratigraphical completeness over the 13 c excursion in other sub tropical successions discontinuities and especially dissolution intervals in many low to middle latitude marine successions elsewhere as in two middle east sections preclude an accurate correlation within the lower part of the 13 c excursion m allisonensis zone p5b three studied sections can provide the best coverage of the sequence of events over the onset and early part of the 13 c excursion in the middle east but as in most known sections probably none constitutes a complete upper palaeocene lower eocene record

a biogenic origin for anomalous fine grained magnetic material at the paleocene eocene boundary at wilson lake new jersey 1 the paleocene eocene thermal maximum which occurred 55 5 ma was caused by a massive release of carbon as indicated by an 3 negative carbon isotope excursion recorded in the marine atmospheric and terrestrial reservoirs one suggested source for the carbon a cometary impactor is based on the sudden appearance and high concentration of single domain sd magnetite in paleocene eocene p e boundary cores from the north atlantic continental margin we evaluate the potential sources of sd magnetite at the p e boundary by presenting new magnetic hysteresis low temperature magnetic remanence and transmission electron microscopy data from the north atlantic coastal ocean our results show a similar increase in sd material but demonstrate that the magnetic material has a biogenic origin these findings indicate that the high concentrations of sd magnetite immediately above the p e boundary are the result of unusual accumulations and or preservation of magnetotactic bacteria such bacteria typically occupy the oxic anoxic transition zone near the sediment water interface or in the water column the high abundances of sd magnetite in sediments from across the shelf may be an artifact of nonsteady state redox conditions and exceptional preservation of sd magnetite it may also indicate that the oxic anoxic redox boundary shifted into the water column the latter explanation implies transient eutrophy of the coastal ocean in this region most likely due to seasonally enhanced runoff and increased stratification and nutrient loading

the impact of paleocene eocene boundary events on middle neritic benthic foraminiferal assemblages from egypt abstract a 25 m upper paleocene to lower eocene marly sequence exposed at gebel duwi quseir red sea coast of egypt provides a good opportunity for studying paleocene eocene p e boundary stratigraphy and events various bio eco and isotope stratigraphic correlations accurately delineate the position of the p e boundary i e the level of stable isotopic excursions and deep sea benthic extinctions in the middle part of this section within zones p5 and np9 in this paper the impact of p e boundary environmental perturbations on benthic foraminiferal communities of the shallow tethyan shelf is examined benthic foraminiferal assemblages from gebel duwi characterized by large frondicularia phosphatica and f nakkadyi in addition to a number of other neritic taxa but without any typical outer neritic bathyal taxa suggest middle neritic 75 100 m deposition throughout the studied interval and only minor relative sea level variations perhaps some 10 20 m across the boundary sea level appears to have been stable yet a distinct faunal turnover marks the p e boundary of this shallow site which in contrast to deep sea records is less abrupt being preceded by a gradual diversity decrease starting some four meters below the boundary moreover most exits are either local or just temporary and thus not true extinctions many lazarus taxa reappear at some point above the boundary while all but one of the disappearing taxa are known from other lower eocene neritic deposits in egypt in general benthic foraminiferal assemblages display low diversities and high dominance values notably anomalinoides aegyptiacus up to 74 suggesting high levels of environmental stress at the sea floor in combination with occasionally very high p b ratio s up to 98 p and generally laminated sediments the character of the benthic assemblage points to a strong influence of recurrent dysoxia and or anoxia we suggest that these resulted from surface eutrophication by intermittent coastal upwelling and reduced ventilation of the bottom environment although these conditions prevailed during most of the time interval studied they were most severe during the latest paleocene and early eocene when eutrophication intensified and the organic carbon flux to the sea floor increased enhanced atmospheric contrasts between the tethys seaway and the african continent resulting in intensified longshore tradewinds may have controlled these changes at the p e boundary the bottom environment became minimally ventilated perhaps due to reduced oxygen advection from deeper waters three meters above the boundary a succession of increasingly diverse assemblages indicate a gradual decrease of environmental stress and a return to more normal conditions although the organic carbon flux to the sea floor remained high

mode and tempo of the paleocene eocene thermal maximum in an expanded section from the venetian pre alps mode and tempo of an expanded paleocene eocene thermal maximum section in the venetian pre alps

the dynamics of global change at the paleocene eocene thermal maximum a data model comparison we integrate published stable isotopic chemical mineralogical and biotic data from the onset of the paleocene eocene thermal maximum petm at site 690 maud rise in the southern ocean the integrated data set documents a sequence of environmental steps including warming of the ocean from the surface downward and modification of its thermal and nutrient structure acidification of the deep ocean and the onset of continental weathering the age of the events with respect to the onset of the petm is calibrated with three different age models the relative and absolute timing of the steps are compared with simulated temperature salinity calcite saturation and dissolved po4 and o2 at different depths in the ocean generated with the uvic earth system climate model of intermediate complexity the simulation supports the top to bottom transfer of heat and carbon and generally agrees with age models in terms of the durations of leads and lags in temperature c isotope and biotic responses moreover the simulation shows that stratification increased and the nutricline strengthened at the onset of the petm these environmental changes explain the abundance of deep dwelling nannoplankton and foraminifera during the early part of the event the modeled calcite saturation is consistent with a harsh deep sea habitat at the time of the benthic foraminiferal extinction

fluvial discharge and sea level changes controlling black shale deposition during the paleocene eocene thermal maximum in the dababiya quarry section egypt abstract the formation of black shales along the tethyan margins at the paleocene eocene thermal maximum petm 55 ma may have been an important feedback mechanism to reduce the warming by excess carbon burial however the detailed evolution of sediment redox conditions during this event is still poorly constrained we address this issue by a high resolution mineralogical and geochemical investigation of the outer neritic dababiya quarry petm section in central egypt which serves as the global boundary stratotype section and point for the base of the eocene there the base of the petm beds corresponds to the onset of sediment lamination indicative of oxygen deficiency at the seafloor the absence of calcium carbonate and a major increase in phyllosilicate abundance and change in detritus sensitive trace elements is indicative of severe carbonate dissolution in addition to enhanced fluvial input erosion of coastal low lands and deposition during low or slightly rising sea level subsequently fully anoxic conditions were established for a short period during the peak phase of the petm as recorded by the strong relative enrichment of redox sensitive trace elements and organic carbon compared to background sediments the decoupling of the fe and mo contents from the detrital fraction may even indicate that euxinic conditions existed with free hydrogen sulfide in the water column concurrent to the onset of anoxia high carbonate and quartz contents as well as high elemental ratios of si al suggest a major drop of siliciclastic sediment supply sediment starvation most likely caused by a rapid sea level rise the final recovery phase of the petm is associated with a progressive restoration of the pre petm siliciclastic sedimentation temporary seasonal anoxic to dysoxic conditions and high phosphorus enrichment followed by carbonate dominated sedimentation and the return to well oxygenated conditions we conclude that after a period of strong fluvial discharge several parameters inherent to the petm e g warming water column stratification and enhanced fluvial discharge may have contributed to the development of anoxia and increased the burial efficiency of organic carbon by reducing water column oxygenation the temporal coincidence of sediment starvation and onset of black shale deposition during the petm suggests that a rapid sea level rise was an additional important triggering factor therefore our results support not only current views that tethyan continental shelf areas may have acted as large carbon sinks during the petm but also indicate that transgressions may have provided an important feedback mechanism for organic carbon drawdown during hyperthermal events

enhanced magnetization of the marlboro clay as a product of soil pyrogenesis at the paleocene eocene boundary abstract the kaolinite rich marlboro clay was deposited on the inner shelf in the salisbury embayment of the u s atlantic margin at the onset of the carbon isotope excursion marking the 56 ma paleocene eocene boundary and is characterized by an anomalously high concentration of magnetic nanoparticles of enigmatic origin that give rise to notably intense bulk magnetization recent studies point to a magnetic assemblage that is dominated by single domain magnetite particles that tend to be isolated rather than arranged in chains the most distinguishing feature of magnetotactic bacteria fossils on the other hand it is very unlikely that the nanoparticles can be condensates of an impact plume given the meter scale thickness of the marlboro clay we obtained new data from a landward proximal site at wilson lake on the new jersey coastal plain and find that the abrupt increase in magnetite nanoparticles is virtually coincident stratigraphically with the recently reported impact spherule layer at the base of the marlboro clay in the same core yet the high field magnetic susceptibility a measure of total iron concentration and strontium isotope values on bulk sediment an indicator of sediment weathering provenance are not different in the marlboro clay from the immediately underlying vincentown formation we suggest that the distinctive magnetic properties of the marlboro clay originated from pyromagnetic soil enhancement by widespread wildfires on the adjoining drainage area the pyrogenetic products were soon washed from the denuded landscape and rapidly deposited as mud waves across the shelf becoming the marlboro clay a few percent of incinerated biomass ends up as calcite known as wood ash stone and can inherit its light carbon isotope composition disseminated wood ash stone entrained in the marlboro clay could contribute to the landward increase in amplitude of the carbon isotope excursion in bulk carbonate data a plausible trigger for the initial conflagration is a fireball from the impact of a sizable extraterrestrial object at moderate range

the climate of the eocene ocean oxygen isotope palaeotemperature estimates are presented for a number of deep sea sediment samples of eocene age covering a wide geographical area these are plotted on a geographical reconstruction for 50 ma the latitudinal temperature gradient at that time was less than half its present value surface temperature at high latitudes was about 10 c and at low latitudes little over 20 c it is concluded that ocean currents must have contributed a greater proportion of the poleward transport of heat than they do at present

paleocene and eocene kaolinite distribution in the south atlantic and southern ocean antarctic climatic and paleoceanographic implications abstract clay mineral associations of paleocene and eocene age have been examined in six drilled sequences from the southern south atlantic and southern ocean these sites are located to provide three depth transects across intermediate water masses widespread abundance of pedogenic smectite at all locations suggests globally warm climates and alternating wet and dry seasons on the adjacent continental margins including antarctica as was the case during the late cretaceous remarkably kaolinite is observed only in paleocene eocene sediments at the highest latitudes of these sites and must have originated from antarctica the restriction of kaolinite to the antarctic region is inferred to have resulted from especially higher rainfall there during the paleocene eocene relative to the lower latitude areas examined this inferred high rainfall is considered to have resulted from globally warm temperatures that increased poleward latent heat transport compensating for a strong heat deficit in the antarctic region relative to the tropics kaolinite was not observed in the latest cretaceous maastrichtian sediments of maud rise antarctica kaolinite first appears in the clay mineralogical assemblages in the earliest paleocene 64 to 64 5 ma at a time of relatively cool intermediate waters and before a warming trend of surface waters currents at intermediate water depths transported fine terrigenous sediments from the antarctica during the latest paleocene and early eocene 59 to 52 ma at a time when the oxygen isotopic strongly in east antarctica during the latest paleocene and early eocene 59 to 59 ma at a time when the oxygen isotopic data indicate maximum warmth of surface and intermediate waters of the southern ocean these are interpreted to reflect a paleocene maximum of antarctic rainfall this development peaked at 57 3 m close to the paleocene eocene boundary a time of maximum warmth based on oxygen isotopic data increased illite content and associated chlorite and random mixed layer clays at the end of the middle eocene 41 ma suggest local development of poorly weathered soils on antarctica favored by a cooling of the southern ocean coeval extension of kaolinite into shallower water depths and similar clay mineral associations in shallower and deeper sites indicate the development of cooler conditions led to an increasing influence of antarctic environments upon intermediate water masses at high latitudes

extreme warming of mid latitude coastal ocean during the paleocene eocene thermal maximum inferences from tex86 and isotope data changes in sea surface temperature sst during the paleocene eocene thermal max imum petm have been estimated primarily from oxygen isotope and mg ca records generated from deep sea cores here we present a record of sea surface temperature change across the paleocene eocene boundary for a nearshore shallow marine section located on the eastern margin of north america the sst record as inferred from tex86 data indicates a minimum of 8 c of warming with peak temperatures in excess of 33 c similar ssts are estimated from planktonic foraminifer oxygen isotope records al though the excursion is slightly larger the slight offset in the oxygen isotope record may reflect on seasonally higher runoff and lower salinity

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