the paleocene eocene transition at mead stream new zealand a southern pacific record of early cenozoic global change mead stream in marlborough new zealand exposes a spectacular 650 m thick stratigraphic section of well bedded micritic limestone chert and marl that was deposited on a south pacific upper continental slope from late cretaceous to middle eocene the 200 m upper paleocene lower eocene succession was examined for its lithology bulk carbonate carbon isotopes and assemblages of radiolarians calcareous nannoplankton and foraminifera so that it could be placed into a global context the interval displays several prominent carbon isotope anomalies and is correlated with south pacific radiolarian zones rp5 to rp9 and calcareous nannofossil zones np6 8 to np12 additionally planktic foraminiferal zones p4 to p6b are identified in uppermost paleocene and lower eocene strata mead stream has a near continuous paleocene lower eocene sediment record and three globally significant climate events the late paleocene carbon isotope maximum pcim the initial eocene thermal maximum ietm and the early eocene climatic optimum eeco have obvious expressions the pcim is a 50 m thick interval of biosiliceous micritic limestone in which 13c is 3 the lower part contains two organic rich biosiliceous mudstone units that may represent expansion of an oxygen minimum zone omz during a global increase in marine biological productivity the ietm is a 4 m thick interval in which 13c drops below 1 5 in a pattern seen at other locations the basal 2 4 m is a distinctive recessed marl rich unit that is defined herein as the dee marl the ietm is marked by a rapid decline in the nannoplankton genus fasciculithus short lived occurrences of discoaster cf araneus and morozovella aequa aequa and significant radiolarian faunal turnover owing to impoverished benthic faunas the benthic foraminiferal extinction event bfee is poorly defined the onset of the eeco is marked by a 1 negative 13c excursion a transition from limestone rich to marl rich facies and a marked decrease in radiolarian abundance compacted sedimentation rates vary between 1 4 2 7 cm kyr for upper paleocene lower eocene strata at mead stream although individual beds with average thickness of 10 cm were deposited too fast to directly represent cycles in orbital parameters time series analysis of bed thicknesses suggests that groups of beds may record milankovitch scale periodicity perhaps with a significant obliquity component thus the relative frequency and thickness of marl and limestone beds in this section is shown to be strongly influenced by climatic changes at a wide range of temporal scales from suborbital and orbital cycles to aberrant short term events and long term trends predominance of marl in ietm and eeco intervals indicates that episodes of extreme global warming resulted in reduced oceanic productivity and increased terrestrial discharge in the high latitude southwestern pacific

from greenhouse to icehouse organic walled dinoflagellate cysts as paleoenvironmental indicators in the paleogene abstract dinoflagellates are an important component of the extant eukaryotic plankton their organic walled hypnozygotic cysts dinocysts provide a rich albeit incomplete history of the group in ancient sediments building on pioneering studies of the late 1970s and 1980s recent drilling in the southern ocean has provided a wealth of new dinocyst data spanning the entire paleogene such multidisciplinary studies have been instrumental in refining existing and furnishing new concepts of paleogene paleoenvironmental and paleoclimatic reconstructions by means of dinocysts because dinocysts notably exhibit high abundances in neritic settings dinocyst based environmental and paleoclimatic information is important and complementary to the data derived from typically more offshore groups as planktonic foraminifera coccolithophorids diatoms and radiolaria by presenting case studies from around the globe this contribution provides a concise review of our present understanding of the paleoenvironmental significance of dinocysts in the paleogene 65 25 ma representing earth s greenhouse icehouse transition this episode holds the key to the understanding of extreme transient climatic change we discuss the potential of dinocysts for the reconstruction of paleogene sea surface productivity temperature salinity stratification and paleo oxygenation along with their application in sequence stratigraphy oceanic circulation and general watermass reconstructions

global dinoflagellate event associated with the late paleocene thermal maximum the late paleocene thermal maximum or lptm ca 55 ma represents a geologically brief time interval 220 k y characterized by profound global warming and associated environmental change the lptm is marked by a prominent negative carbon isotope excursion cie interpreted to reflect a massive and abrupt input of 12 c enriched carbon to the ocean atmosphere reservoir possibly as a result of catastrophic gas hydrate release on time scales equivalent to present day rates of anthropogenic carbon input the lptm corresponds to important changes in the global distribution of biota including mass extinction of marine benthic organisms the dinoflagellate cyst record indicates that surface dwelling marine plankton in marginal seas also underwent significant perturbations during the lptm we report on the dramatic response of representatives of the genus apectodinium from two upper paleocene lower eocene sections in the southern new zealand and northern austria hemispheres where the dinoflagellate records are directly correlated with the cie benthic foraminifera extinction event and calcareous nannofossil zonation the results indicate that the inception of apectodinium dominated assemblages appears to be synchronous on a global scale and that the event is precisely coincident with the beginning of the lptm apectodinium markedly declined in abundance near the end of the lptm this apectodinium event may be associated with 1 exceptionally high global sea surface temperatures and or 2 a significant increase in marginal marine surface water productivity such a globally synchronous acme of dinoflagellate cysts is unprecedented within the dinoflagellate cyst fossil record

late palaeocene early eocene dinoflagellate cysts from the turgay strait kazakhstan correlations across ancient seaways abstract the results of a quantitative palynological analysis emphasizing organic walled dinoflagellate cysts dinocysts of palaeocene eocene deposits exposed in the sokolovsky quarry turgay trough northern kazakhstan are presented here located in the ancient turgay strait a former seaway presumed to have connected the tethyan and boreal oceans and seas in the early palaeogene the sokolovsky quarry outcrop occupies a key position for the analysis of connections between these realms in general the dinocyst succession of sokolovsky closely resembles coeval arctic ocean north sea basin counterparts only in one interval endemic and or possibly tethyan species co occur the successive dinocyst assemblages allow recognition of the late palaeocene early eocene p5a p5b p6a p6b and e2 zones established in the north sea basin the succession is interpreted to represent parts of several third order sea level cycles correlative with those recognised in the north sea basin detailed comparison with similar studies from southeastern england allows the recognition of parts of third order cycles thanetian 1 tht 1 2 4 5 and ypresian ypr 3 in addition two important stratigraphic gaps within the palaeocene eocene succession are recognised possibly reflecting times of sea level lowering these gaps are inferred from 1 the absence of a complete p5b p6a transition 2 the absence of zone e1 and 3 bio sequence stratigraphy combined results indicate that the turgay strait flooded from the north between 57 8 and 57 1 ma cycles tht 1 and 2 in part with a minor missing section during the second phase of turgay flooding 56 4 55 3 ma evidence may be taken to indicate increased influence from the tethyan ocean and or warmer conditions deposits reflecting the late palaeocene thermal maximum associated with this interval are present at sokolovsky quarry this interval is marked by abundant apectodinium spp including a augustum and organic rich layers a third flooding is correlative to the london clay transgression from 54 5 ma from our study no decisive evidence has become available that confirms that a connection between the arctic and tethyan oceans via the turgay strait in the early palaeogene existed nevertheless during intervals of major sea level fall the turgay strait depression may be regarded to have been an important feature for migrating terrestrial biota four new wetzeliellioid taxa apectodinium sp a apectodinium sp b wilsonidium sp a and wilsonidium sp b are described from the palaeocene part of the section

late eocene to early oligocene dinoflagellate cysts from the priabonian type area northeast italy biostratigraphy and paleoenvironmental interpretation abstract marginal marine late eocene through early oligocene dinoflagellate cyst successions have been studied from the type area of the priabonian stage northeast italy the results allow the recognition of dinoflagellate zones previously defined in bio and magnetostratigraphically well calibrated pelagic sequences from central italy thus providing a first order correlation of the priabonian stage to the standard chronostratigraphic scale with unprecedented precision within this detailed biostratigraphic framework successive shifts in the composition of the dinoflagellate cyst assemblages are interpreted in terms of sea level and sea surface temperature sst fluctuations the evaluation of ecologically and sedimentary controlled changes in the composition of dinoflagellate cyst assemblages in combination with sequence stratigraphic analysis allows the reconstruction of third and fourth order sea level fluctuations the third order sea level fluctuations appear to correspond to exxon cycles ta4 1 4 5 the stratigraphically and palaeoenvironmentally important late eocene dinoflagellate cyst species glaphyrocysta priabonensis sp nov is formally described

quantitative analysis of debris flow flexible barrier capacity from momentum and energy perspectives abstract in depth understanding of debris structure interaction is hindered by a lack of physical data of debris flow impacting structures this study reports a set of centrifuge experiments investigating the impact load exerted by debris flow on rigid and flexible barriers a combination of high speed imagery and load displacement sensors enabled a comprehensive grasp of the impact details including flow depth velocity impact pressure bending moment and cable force elongation of flexible barrier test results reveal that the debris structure interaction plays a major role in the energy dissipation and impact load reconstruction the built up of static load behind the barrier occurs simultaneously with the grow up of impact force as a result the momentum flux of incoming flow is not merely a surrogate of the impact force a quantitative analysis from the energy perspective has been conducted under the experimental conditions of this study debris flow impact results in over 90 of debris energy dissipated through the internal and boundary shearing leaving

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

sedimentary trace element constraints on the role of north atlantic igneous province volcanism in late paleocene early eocene environmental change abstract a growing body of geologic evidence suggests that emplacement of the north atlantic igneous province naip played a major role in global warming during the early paleogene as well as in the transient paleocene eocene thermal maximum petm event a 5 million year record of major and trace element abundances spanning 56 to 51 ma at deep sea drilling project sites 401 and 549 confirms that the majority of naip volcanism occurred as subaerial flows thus the trace element records provide constraints on the nature and scope of the environmental impact of the naip during the late paleocene early eocene interval subaerial volcanism would have injected mantle co2 directly into the atmosphere resulting in a more immediate increase in atmospheric greenhouse gas abundances than co2 input through submarine volcanism the lack of significant hydrothermalism contradicts recently proposed mechanisms for thermally destabilizing methane hydrate reservoirs during the petm any connection between naip volcanism and petm warming had to occur through the atmosphere

dissociation of oceanic methane hydrate as a cause of the carbon isotope excursion at the end of the paleocene isotopic records across the latest paleocene thermal maximum lptm indicate that bottom water temperature increased by more than 4 c during a brief time interval 104 years of the latest paleocene 55 6 ma there also was a coeval 2 to 3 excursion in the 13c of the ocean atmosphere inorganic carbon reservoir given the large mass of this reservoir a rapid 13c shift of this magnitude is difficult to explain within the context of conventional hypotheses for changing the mean carbon isotope composition of the ocean and atmosphere however a direct consequence of warming bottom water temperature from 11 to 15 c over 104 years would be a significant change in sediment thermal gradients and dissociation of oceanic ch4 hydrate at locations with intermediate water depths in terms of the present day oceanic ch4 hydrate reservoir thermal dissociation of oceanic ch4 hydrate during the lptm could have released greater than 1 1 to 2 1 1018 g of carbon with a 13c of approximately 60 the release and subsequent oxidation of this amount of carbon is sufficient to explain a 2 to 3 excursion in 13c across the lptm fate of ch4 in oceanic hydrates must be considered in developing models of the climatic and paleoceanographic regimes that operated during the lptm

long term sea level fluctuations driven by ocean basin dynamics earth9s long term sea level history is characterized by widespread continental flooding in the cretaceous period 145 to 65 million years ago followed by gradual regression of inland seas however published estimates of the late cretaceous sea level high differ by half an order of magnitude from 40 to 250 meters above the present level the low estimate is based on the stratigraphy of the new jersey margin by assimilating marine geophysical data into reconstructions of ancient ocean basins we model a late cretaceous sea level that is 170 85 to 270 meters higher than it is today we use a mantle convection model to suggest that new jersey subsided by 105 to 180 meters in the past 70 million years because of north america9s westward passage over the subducted farallon plate this mechanism reconciles new jersey margin based sea level estimates with ocean basin reconstructions

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

abrupt increase in seasonal extreme precipitation at the paleocene eocene boundary a prominent increase in atmospheric co at the paleocene eocene boundary ca 55 ma led to the warmest earth of the cenozoic for similar to 100 k y high resolution studies of continental flood plain sediment records across this boundary can provide crucial information on how the hydrological cycle responds to rapidly changing co2 here we show from continental records across the paleocene eocene boundary in the spanish pyrenees a subtropical paleosetting that during the early most intense phase of co2 rise normal semiarid coastal plains with few river channels of 10 200 m width were abruptly replaced by a vast conglomeratic braid plain covering at least 500 km 2 and most likely more than 2000 km 2 this braid plain is interpreted as the proximal parts of a megafan carbonate nodules in the megafan deposits attest to seasonally dry periods and together with megafan development imply a dramatic increase in seasonal rain and an increased intra annual humidity gradient the megafan formed over a few thousand years to similar to 10 k y directly after the paleocene eocene boundary only repeated severe floods and rainstorms could have contributed the water energy required to transport the enormous amounts of large boulders and gravel of the megafan during this short time span the findings represent evidence for considerable changes in regional hydrological cycles following greenhouse gas emissions less

a novel proxy for terrestrial organic matter in sediments based on branched and isoprenoid tetraether lipids we propose a novel tracer for terrestrial organic carbon in sediments based on the analysis of tetraether lipids using high performance liquid chromatography mass spectrometry hplc ms analysis of terrestrial soil and peats shows that branched tetraether lipids are predominant in terrestrial environments in contrast to crenarchaeol the characteristic membrane lipid of non thermophilic crenarchaeota which is especially abundant in the marine and lacustrine environment based on these findings an index was developed the so called branched and isoprenoid tetraether bit index based on the relative abundance of terrestrially derived tetraether lipids versus crenarchaeol this bit index was applied to surface sediments from the angola basin where it was shown to trace the outflow of the congo river furthermore analyses of particulate organic matter from the north sea showed relatively higher bit indices in water column particulate organic matter near large river inputs a survey of globally distributed marine and lacustrine surface sediments shows that the bit index in these environments correlates with the relative fluvial input of terrestrial organic material making this index generally applicable the new proxy allows the rapid assessment of the fluvial input of terrestrial organic material in immature sediments up to 100 ma old

basaltic explosive volcanism but no comet impact at the paleocene eocene boundary high resolution chemical and isotopic records from egypt spain and denmark in the search for a triggering mechanism for the paleocene eocene p e boundary event 55 ma centimeter resolution chemical e g ir os pt and isotope e g os o 187 os 188 he 3 he 4 sr 87 sr 86 records across this boundary have been established for six uplifted marine sections in egypt spain and denmark the sections studied represent some of the stratigraphically most complete records across the onset of the carbon isotopic excursion cie and associated benthic foraminifera extinctions that mark the paleocene eocene boundary high sensitivity analyses failed to uncover evidence of extraterrestrial element or isotope enrichments in the six sections refuting the hypothesis of a major comet impact at the boundary preliminary searches for other impact indicative features such as spherules or shocked quartz also gave negative results in the danish section studied three basaltic ir rich ash layers occur at the paleocene eocene boundary but no similar ashes were found in egypt or spain the three ashes represent the earliest known manifestation of an unusual i to 2 million year long phase of explosive basaltic volcanism in the faero greenland region this volcanism is synchronous with major flood basalt effusions in east greenland and is associated with prominent paleogeographic changes in the high latitude north atlantic region discharge of mantle derived os to seawater during this volcanism may explain a small decrease in os o 187 os o 188 ratio at the paleocene eocene boundary in the zumaya section in spain the environmental perturbations at the paleocene eocene boundary appear to have been triggered by basaltic volcanism but any model for the detailed causal relation remains speculative c 2004 elsevier b v all rights reserved less

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

a benthic foraminiferal record of paleocene sea level and trophic redox conditions at gebel aweina egypt we quantitatively analyzed benthic foraminiferal assemblages in order to reveal biotic and paleoenvironmental trends in the paleocene section of gebel aweina egypt on the southern tethyan shelf the first correspondence axis ranks taxa along an empirically derived bathymetric gradient with neritic taxa e g discorbis duwi and haplophragmoides walteri opposed to bathyal taxa e g nuttallides truempyi and gavelinella beccari ormis the estimated paleodepth as reflected by the various assemblages was mostly 200 m but varied between 50 m p3a np4 and 300 m p4 n p8 the resultant four relative sea level cycles appear to be at least of regional extent and may in part be eustatically controlled the second correspondence axis reflects trends in trophic and redox development low food high oxygen conditions prevailed during biochrons plc p3b np4 np5 and late p4 np8 when assemblages were mostly dominated by cibicidoides spp most oligotrophic conditions coincided with maximum paleodepth intermediate trophic levels were established during middle p4 np6 and early p5 np9 from the level of the latest paleocene benthic extinction event bee middle p5 and np9 onwards until biochron p6a np10 assemblages dominated by buliminids marked increased trophic levels and reduced ventilation probably resulting from enhanced surface productivity enhanced surface productivity along the southern tethyan margin started during biochron p4 and at least on some shelves intensified after the bee increasing productivity during the latest paleocene contrasts with global trends this may be expected during climatic warming and an expanding trophic resource continuum leading to regionally intensified eutrophy and oligotrophy high productivity through upwelling along the southern tethyan provides support for gcm predictions of intense wind stress in this region during the warm late to latest paleocene 1998 elsevier science b v

refining ancient carbon dioxide estimates significance of coccolithophore cell size for alkenone based pco2 records 1 long term alkenone based pco2 records are widely applied in paleoclimate evaluations these pco2 estimates are based on records of the carbon isotope fractionation that occurs during marine haptophyte photosynthesis p37 2 in addition to the concentration of aqueous co2 co2 aq the magnitude of p37 2 is also influenced by algal growth rates and cell geometry to date the influence of haptophyte cell geometry on the expression of ancient p37 2 values has received little attention this study evaluates changes in cell geometry of ancient alkenone producing algae at deep see drilling project site 516 in the southwest atlantic ocean by analyzing individual coccolith dimensions which are proportional to algal cell volume and surface area we show that during part of the early miocene mean cell sizes of alkenone producing algae were smaller relative to modern emiliania huxleyi cell size variations coincide with significant changes in p37 2 with a distinct 6 decrease in p37 2 at 20 3 ma associated with a 27 increase in haptophyte cell sizes these changes in cell size impact p37 2 based interpretations of growth rate variation and co2 aq estimates for this southwest atlantic site after correcting for cell geometry co2 aq estimates at site 516 are consistent with those reported from other oligotrophic sites during this time resulting in overall low atmospheric pco2 estimates 350 ppmv for the early miocene

tertiary oxygen isotope synthesis sea level history and continental margin erosion tertiary benthic and planktonic foraminiferal oxygen isotope records are correlated to a standard geomagnetic polarity time scale making use of improved chronostratigraphic control and additional oligocene isotope data synchronous changes in both benthic and planktonic 18o values which occurred in the oligocene to miocene 36 5 2 ma are interpreted in part to represent ice growth and decay the inferred ice growth events correlate with erosion on passive continental margins as interpreted from seismic and chronostratigraphic records this association is consistent with a link between oligocene to miocene erosional events and rapid 15 m m y glacioeustatic lowerings of about 50 m high benthic foraminiferal 18o values suggest the presence of continental ice sheets during much of the oligocene to recent 36 0 ma substantially ice free conditions probably existed throughout the paleocene and eocene 66 36 ma the mechanisms and rates of sea level change apparently were different between the early and late tertiary with glacioeustatic changes restricted to the past 36 m y pre oligocene erosion on passive continental margins was caused by eustatic lowerings resulting from global spreading rate changes we apply a model which suggests that large areas of the continental shelves were subaerially exposed during such tectonoeustatic lowstands stimulating slope failure and submarine erosion the different mechanisms and rates of eustatic change may have caused contrasting erosional patterns between the early and late tertiary on passive continental margins this speculation needs to be confirmed by examination of data from several passive margins

climate and sea level perturbations during the incipient eocene thermal maximum evidence from siliciclastic units in the basque basin ermua zumaia and trabakua pass northern spain abstract based on carbon isotope stratigraphy and lithology a revised high resolution correlation is proposed between sections spanning the incipient eocene thermal maximum ietm in the basque region northern spain in three studied sections the ietm event is represented by a prominent non to low calcareous siliciclastic unit su 4 20 5 m thick during formation of the su sedimentation rates for siliciclastic material increased by a factor of two to five whereas detrital grain size decreased significantly kaolinite and chlorite became more abundant in the clay fraction and calcite dissolution in the water column intensified the su reflects a significant change in climate and hydrological regime towards a warmer and seasonally drier climate the drying caused perennial vegetation cover to collapse and led to increased continental erosion but also to reduced hydrodynamic energy of freshwater debouching into the oceans a coeval relative sea level fall probably related to tectonic uplift or doming affecting major parts of western europe increased the land sea slope and further enhanced erosion rates palynological studies support periodic vegetation during seasonal rain instead of permanent conifer forests prominent caliche soils in coeval continental deposits in northern spain also support warm semiarid conditions during the ietm event net evaporation increased under the subtropical high pressure cells including the basque region whereas more northerly latitudes became more wet the su has a similar origin as detrital units previously assigned to the early palaeogene so called siderolithic discharge in other parts of western europe

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

the apectodinium acme and terrestrial discharge during the paleocene eocene thermal maximum new palynological geochemical and calcareous nannoplankton observations at tawanui new zealand manifestations of profound perturbations in biogeochemical systems during the paleocene eocene thermal maximum petm include a prominent global negative 13c and a pronounced increase in the relative abundance of dinoflagellate cysts dinocysts assigned to the genus apectodinium while motile representatives of apectodinium were most likely thermophilic and heterotrophic the underlying causes of this dinoflagellate response are not well understood here we provide new insight by examining the palynology chemistry and calcareous nannoplankton across the petm in a continental slope section at tawanui new zealand across the petm marked changes in the relative abundance of apectodinium vary antithetically with significant changes in the 13c of carbonate and organic matter in general the high relative abundance of apectodinium relates to enhanced concentrations of dinocysts signifying a bloom of apectodinium in surface waters during the petm changes in apectodinium and 13c records correspond to variations in many other parameters including a smaller negative shift in bulk carbonate 13c than expected increased terrestrial palynomorphs elevated toc and c n ratios lower carbonate contents higher sio2 and al2o3 contents and lower si al ratios all of these variations can be explained by an increase in delivery of terrigenous material to the continental margin a peak in the relative abundance of glaphyrocysta dinocysts at the onset of the petm may indicate greater down slope transport of neritic material changes in calcareous nannoplankton abundances suggest increased nutrient availability in surface waters during the petm the combined results show that apectodinium dominated assemblages global perturbations in carbon isotopes and enhanced terrigenous delivery closely correspond in time at tawanui a sudden and massive carbon injection to the ocean atmosphere system may have enhanced weathering and increased terrigenous inputs to continental margins during the petm we further suggest that these inputs caused the apectodinium acme by elevating primary productivity in marginal seas

on the duration of the paleocene eocene thermal maximum petm 1 the paleocene eocene thermal maximum petm is one of the best known examples of a transient climate perturbation associated with a brief but intense interval of global warming and a massive perturbation of the global carbon cycle from injection of isotopically light carbon into the ocean atmosphere system one key to quantifying the mass of carbon released identifying the source s and understanding the ultimate fate of this carbon is to develop high resolution age models two independent strategies have been employed cycle stratigraphy and analysis of extraterrestrial helium heet both of which were first tested on ocean drilling program odp site 690 these two methods are in agreement for the onset of the petm and initial recovery or the clay layer main body but seem to differ in the final recovery phase of the event above the clay layer where the carbonate contents rise and carbon isotope values return toward background values here we present a state of the art age model for the petm derived from a new orbital chronology developed with cycle stratigraphic records from sites drilled during odp leg 208 walvis ridge southeastern atlantic integrated with published records from site 690 weddell sea southern ocean odp leg 113 during leg 208 five paleocene eocene p e boundary sections sites 1262 to 1267 were recovered in multiple holes over a depth transect of more than 2200 m at the walvis ridge yielding the first stratigraphically complete p e deep sea sequence with moderate to relatively high sedimentation rates 1 to 3 cm ka where a is years a detailed chronology was developed with nondestructive x ray fluorescence xrf core scanning records on the scale of precession cycles with a total duration of the petm now estimated to be 170 ka the revised cycle stratigraphic record confirms original estimates for the duration of the onset and initial recovery but suggests a new duration for the final recovery that is intermediate to the previous estimates by cycle stratigraphy and heet

on the duration of magnetochrons c24r and c25n and the timing of early eocene global warming events implications from the ocean drilling program leg 208 walvis ridge depth transect 1 five sections drilled in multiple holes over a depth transect of more than 2200 m at the walvis ridge se atlantic during ocean drilling program odp leg 208 resulted in the first complete early paleogene deep sea record here we present high resolution stratigraphic records spanning a 4 3 million yearlong interval of the late paleocene to early eocene this interval includes the paleocene eocene thermal maximum petm as well as the eocene thermal maximum etm 2 event a detailed chronology was developed with nondestructive x ray fluorescence xrf core scanning records and shipboard color data these records were used to refine the shipboard derived spliced composite depth for each site and with a record from odp site 1051 were then used to establish a continuous time series over this interval extensive spectral analysis reveals that the early paleogene sedimentary cyclicity is dominated by precession modulated by the short 100 kyr and long 405 kyr eccentricity cycles counting of precession related cycles at multiple sites results in revised estimates for the duration of magnetochrons c24r and c25n direct comparison between the amplitude modulation of the precession component derived from xrf data and recent models of earth s orbital eccentricity suggests that the onset of the petm and etm2 are related to a 100 kyr eccentricity maximum both events are approximately a quarter of a period offset from a maximum in the 405 kyr eccentricity cycle with the major difference that the petm is lagging and etm2 is leading a 405 kyr eccentricity maximum absolute age estimates for the petm etm2 and the magnetochron boundaries that are consistent with recalibrated radiometric ages and recent models of earth s orbital eccentricity cannot be precisely determined at present because of too large uncertainties in these methods nevertheless we provide two possible tuning options which demonstrate the potential for the development of a cyclostratigraphic framework based on the stable 405 kyr eccentricity cycle for the entire paleogene

compound specific radiocarbon dating of the varved holocene sedimentary record of saanich inlet canada 1 the radiocarbon contents of various biomarkers extracted from the varve counted sediments of saanich inlet canada were determined to assess their applicability for dating purposes calibrated ages obtained from the marine planktonic archaeal biomarker crenarchaeol compared favorably with varve count ages the same conclusion could be drawn for a more general archaeal biomarker gdgt 0 although this biomarker proved to be less reliable due to its less specific origin the results also lend support to earlier indications that marine crenarchaeota use dissolved inorganic carbon dic as their carbon source the average reservoir age offset r of 430 years determined using the crenarchaeol radiocarbon ages varied by 110 years this may be caused by natural variations in ocean atmosphere mixing or upwelling at the ne pacific coast but variability may also be due to an inconsistency in the marine calibration curve when used at sites with high reservoir ages

north american continental margin records of the paleocene eocene thermal maximum implications for global carbon and hydrological cycling the impacts of the paleocene eocene thermal maximum petm 55 ma one of the most rapid and extreme warming events in earth history are well characterized in open marine and terrestrial environments but are less so on continental margins a major carbon sink here we present stable isotope carbonate content organic matter content and c n ratio records through the petm from new outcrop sections in california and from cores previously drilled on the new jersey margin foraminifer 18o data suggest that midlatitude shelves warmed by a similar magnitude as the open ocean 5 c 8 c while the carbon isotope excursion cie recorded both in carbonate and organic matter 13c records is slightly larger 3 3 4 5 than documented in open ocean records sediment accumulation rates increase dramatically during the cie in marked contrast to the open ocean sites in parallel mass accumulation rates of both organic and inorganic carbon also increased by an order of magnitude the estimated total mass of accumulated carbon in excess of pre cie rates suggests that continental margins at least along north america became carbon sinks during the cie mainly because of weathering feedbacks and rising sea level this result is significant because it implies that the negative feedback role of carbon burial on continental margins was greater than previously recognized

arctic late paleocene early eocene paleoenvironments with special emphasis on the paleocene eocene thermal maximum lomonosov ridge integrated ocean drilling program expedition 302 we reconstruct the latest paleocene and early eocene 57 50 ma environmental trends in the arctic ocean and focus on the paleocene eocene thermal maximum petm 55 ma using strata recovered from the lomonosov ridge by the integrated ocean drilling program expedition 302 the lomonosov ridge was still partially subaerial during the latest paleocene and earliest eocene and gradually subsided during the early eocene organic dinoflagellate cyst dinocyst assemblages point to brackish and productive surface waters throughout the latest paleocene and early eocene dinocyst assemblages are cosmopolitan during this time interval suggesting warm conditions which is corroborated by tex86 reconstructed temperatures of 15 18 c inorganic geochemistry generally reflects reducing conditions within the sediment and euxinic conditions during the upper lower eocene spectral analysis reveals that the cyclicity recorded in x ray fluorescence scanning fe data from close to eocene thermal maximum 2 53 ma presence confirmed by dinocyst stratigraphy is related to precession within the lower part of the petm proxy records indicate enhanced weathering runoff anoxia and productivity along with sea level rise on the basis of total organic carbon content and variations in sediment accumulation rates excess organic carbon burial in the arctic ocean appears to have contributed significantly to the sequestration of injected carbon during the petm

astronomical climate control on paleosol stacking patterns in the upper paleocene lower eocene willwood formation bighorn basin wyoming the willwood formation of the bighorn basin wyoming usa is a thick succession of upper paleocene and lower eocene fluvial floodplain sandstones and mudstones reddish paleosols formed on the floodplain mudstones alternate rhythmically on various scales with heterolithic intervals of small channel sandstones and mudstones showing weak pedogenesis spectral analysis of redness in the willwood successions at polecat bench and red butte reveals significant spectral peaks corresponding to cycle thicknesses of 8 and 3 m the 8 m cycle reflects distinct clusters of 3 5 paleosols age constraints show that the period of this cycle closely matches the 21 k y climatic precession cycle the 3 m cycle corresponds to individual paleosols with a period of 7 8 k y this period is similar to millennial scale sub milankovitch cycles found in marine and lacustrine successions of pliocene pleistocene age precession and millennial scale climate variations probably affected paleosol development through cyclic changes from predominantly overbank to predominantly channel avulsion deposition with the latter periodically halting soil formation because of high sediment accumulation a new age model was developed for the paleocene eocene carbon isotope excursion cie at polecat bench based on the precessional origin of paleosol clusters the main body of the cie spans 5 5 precession cycles or 115 k y and the recovery tail of the cie spans 2 precession cycles or 42 k y this outcome is consistent with and independently confirms recent estimates of cie duration based on deep sea cores

north atlantic volcanic margins dimensions and production rates early tertiary lithospheric breakup between eurasia and greenland was accompanied by a transient 3 m y igneous event emplacing both the onshore flood basalts of the north atlantic volcanic province navp and huge extrusive complexes along the continent ocean transition on the rifted continental margins seismic data show that volcanic margins extend 2600 km along the early eocene plate boundary in places underlain by high velocity 7 2 7 7 km s lower crustal bodies quantitative calculations of navp dimensions considered minimum estimates reveal an areal extent of 1 3 106 km2 and a volume of flood basalts of 1 8 106 km3 yielding a mean eruption rate of 0 6 km3 yr or 2 4 km3 yr if two thirds of the basalts were emplaced within 0 5 m y the total crustal volume is 6 6 106 km3 resulting in a mean crustal accretion rate of 2 2 km3 yr thus navp ranks among the world s larger igneous provinces if the volcanic margins are considered the velocity structure of the expanded crust seaward of the continent ocean boundary differs from standard oceanic and continental crustal models based on seismic velocities this volcanic margin crust can be divided into three units of which the upper unit corresponds to basaltic extrusives the regionally consistent velocity structure and geometry of the crustal units suggest that the expanded crust including the high velocity lower crust which extends some distance landward of the continent ocean boundary was emplaced during and subsequent to breakup the volcanic margin crust was formed by excess melting within a wide zone of asthenospheric upwelling probably reflecting the interaction of a mantle plume and a lithosphere already extending

shelf and open ocean calcareous phytoplankton assemblages across the paleocene eocene thermal maximum implications for global productivity gradients abrupt global warming and profound perturbation of the carbon cycle during the paleocene eocene thermal maximum petm ca 55 ma have been linked to a massive release of carbon into the ocean atmosphere system increased phytoplankton productivity has been invoked to cause subsequent co2 drawdown cooling and environmental recovery however interpretations of geochemical and biotic data differ on when and where this increased productivity occurred here we present high resolution nannofossil assemblage data from a shelf section the u s geological survey usgs drill hole at wilson lake new jersey and an open ocean location ocean drilling program odp site 1209 paleoequatorial pacific these data combined with published biotic records indicate a transient steepening of shelf offshelf trophic gradients across the petm onset and peak with a decrease in open ocean productivity coeval with increased nutrient availability in shelf areas productivity levels recovered in the open ocean during the later stages of the event which coupled with intensified continental weathering rates may have played an important role in carbon sequestration and co2 drawdown

beyond methane towards a theory for the paleocene eocene thermal maximum abstract extreme global warmth and an abrupt negative carbon isotope excursion during the paleocene eocene thermal maximum petm have been attributed to a massive release of methane hydrate from sediments on the continental slope 1 however the magnitude of the warming 5 to 6 c 2 3 and rise in the depth of the ccd 2 km 4 indicate that the size of the carbon addition was larger than can be accounted for by the methane hydrate hypothesis additional carbon sources associated with methane hydrate release e g pore water venting and turbidite oxidation are also insufficient we find that the oxidation of at least 5000 gt c of organic carbon is the most likely explanation for the observed geochemical and climatic changes during the petm for which there are several potential mechanisms production of thermogenic ch4 and co2 during contact metamorphism associated with the intrusion of a large igneous province into organic rich sediments 5 is capable of supplying large amounts of carbon but is inconsistent with the lack of extensive carbon loss in metamorphosed sediments as well as the abrupt onset and termination of carbon release during the petm a global conflagration of paleocene peatlands 6 highlights a large terrestrial carbon source but massive carbon release by fire seems unlikely as it would require that all peatlands burn at once and then for only 10 to 30 ky in addition this hypothesis requires an order of magnitude increase in the amount of carbon stored in peat the isolation of a large epicontinental seaway by tectonic uplift associated with volcanism or continental collision followed by desiccation and bacterial respiration of the aerated organic matter is another potential mechanism for the rapid release of large amounts of co2 in addition to the oxidation of the underlying marine sediments the desiccation of a major epicontinental seaway would remove a large source of moisture for the continental interior resulting in the desiccation and bacterial oxidation of adjacent terrestrial wetlands

hyperstratification following glacial overturning events in the northern arabian sea 1 correlations between arabian sea organic carbon and gisp2 18o records indicate a pronounced oxygen minimum zone omz during interstadials whereas well oxygenated conditions prevailed during stadials local deep winter mixing ventilated intermediate water during the coldest stadials corresponding to north atlantic heinrich events here we show that in the arabian sea periods of climatic warming following heinrich events h6 h4 and the younger dryas yd are characterized by dominant polysphaeridium zoharyi dinoflagellate cysts the finding of assemblages dominated by p zoharyi in the open ocean is unusual because today similar assemblages are restricted to lagoonal settings it is postulated that the highly saline mixed layer and the strong density gradient which characterized arabian sea hydrography after h6 h4 and the yd simulated a shallow seafloor thereby enabling germination of cysts prior to sinking the strong density gradient following cold stadials should have facilitated the rapid reestablishment of a pronounced omz during interstadials

abrupt climate change and transient climates during the paleogene a marine perspective detailed investigations of high latitude sequences recently collected by the ocean drilling program odp indicate that periods of rapid climate change often culminated in brief transient climates with more extreme conditions than subsequent long term climates two examples of such events have been identified in the paleogene the first in latest paleocene time in the middle of a warming trend that began several million years earlier the second in earliest oligocene time near the end of a middle eocene to late oligocene global cooling trend superimposed on the earlier event was a sudden and extreme warming of both high latitude sea surface and deep ocean waters imbedded in the latter transition was an abrupt decline in high latitude temperatures and the brief appearance of a full size continental ice sheet on antarctica in both cases the climate extremes were not stable lasting for less than a few hundred thousand years indicating a temporary or transient climate state geochemical and sedimentolog

cenozoic global sea level sequences and the new jersey transect results from coastal plain and continental slope drilling the new jersey sea level transect was designed to evaluate the relationships among global sea level eustatic change unconformity bounded sequences and variations in subsidence sediment supply and climate on a passive continental margin by sampling and dating cenozoic strata from coastal plain and continental slope locations we show that sequence boundaries correlate within 0 5 myr regionally onshore offshore and interregionally new jersey alabama bahamas implicating a global cause sequence boundaries correlate with 18o increases for at least the past 42 myr consistent with an ice volume glacioeustatic control although a causal relationship is not required because of uncertainties in ages and correlations evidence for a causal connection is provided by preliminary miocene data from slope site 904 that directly link 18o increases with sequence boundaries we conclude that variation in the size of ice sheets has been a primary control on the formation of sequence boundaries since 42 ma we speculate that prior to this the growth and decay of small ice sheets caused small amplitude sea level changes 20 m in this supposedly ice free world because eocene sequence boundaries also appear to correlate with minor 18o increases subsidence estimates backstripping indicate amplitudes of short term million year scale lowerings that are consistent with estimates derived from 18o studies 25 50 m in the oligocene middle miocene and 10 20 m in the eocene and a long term lowering of 150 200 m over the past 65 myr consistent with estimates derived from volume changes on mid ocean ridges although our results are consistent with the general number and timing of paleocene to middle miocene sequences published by workers at exxon production research company our estimates of sea level amplitudes are substantially lower than theirs lithofacies patterns within sequences follow repetitive predictable patterns 1 coastal plain sequences consist of basal transgressive sands overlain by regressive highstand silts and quartz sands and 2 although slope lithofacies variations are subdued reworked sediments constitute lowstand deposits causing the strongest most extensive seismic reflections despite a primary eustatic control on sequence boundaries new jersey sequences were also influenced by changes in tectonics sediment supply and climate during the early to middle eocene low siliciclastic and high pelagic input associated with warm climates resulted in widespread carbonate deposition and thin sequences late middle eocene and earliest oligocene cooling events curtailed carbonate deposition in the coastal plain and slope respectively resulting in a switch to siliciclastic sedimentation in onshore areas oligocene sequences are thin owing to low siliciclastic and pelagic input and their distribution is patchy reflecting migration or progradation of depocenters in contrast miocene onshore sequences are thicker reflecting increased sediment supply and they are more complete downdip owing to simple tectonics we conclude that the new jersey margin provides a natural laboratory for unraveling complex interactions of eustasy tectonics changes in sediment supply and climate change

a high resolution north sea eocene dinocyst zonation abundant dinoflagellate cysts dinocysts from eocene strata of the north sea exhibit a consistent succession of events based on the analysis of 120 wells from quadrant 3 in the north to quadrants 21 and 22 in the south these events have a constant relationship with stratigraphic sequences and subsequences throughout the area eight eocene dinocyst zones and 23 subzones and the uppermost palaeocene apectodinium augustum biozone are defined by last occurrence or abundance events the north sea dinocyst succession is similar to that in denmark northwest germany belgium the netherlands and southern england permitting correlation with calcareous nannoplankton zones for sections in these areas and hence allowing correlation of north sea stratigraphy with northwest european and worldwide events

regional uplift gas hydrate dissociation and the origins of the paleocene eocene thermal maximum much of the north atlantic region experienced hundreds of metres of transient uplift during the latest paleocene regional uplift should cause dissociation of gas hydrates stored in marine sedimentary strata and the subsequent release of carbon to the atmosphere should enhance warming through the greenhouse effect we have developed models of the spatial distribution of uplift to match observational constraints from sedimentary basins fringing the north atlantic in order to provide quantitative estimates of the carbon released upon uplift these models are coupled to a simple parameterisation of carbon storage in sub seafloor gas hydrates results of modelling indicate that large quantities of carbon can be released by uplift with some models generating over 2000 gt of carbon release the possibility that latest paleocene regional uplift occurred over the same time interval as onset of the paleocene eocene thermal maximum petm around 30 kyr cannot be ruled out using current stratigraphical observations or mantle convection models in this case the uplift mechanism alone can account for the magnitude and timing of the carbon isotope excursion associated with the petm alternatively if the duration of latest paleocene uplift was closer to the upper bound of around 1 myr or if other paleocene uplift events were equally significant then gas hydrate dissociation upon uplift could have contributed to longer term changes in ocean temperature and carbon isotope composition through the late paleocene these temperature changes in combination with development of the north atlantic land bridge during the latest paleocene culmination of uplift may be able to force rapid changes in ocean circulation and cause phenomena such as the petm

visions of ice sheets in a greenhouse world abstract backstripped eustatic estimates from new jersey and the russian platform show large 25 m and rapid 18 o record highlights the enigma this was the warmest interval of the past 200 my yet it was bracketed by two inferred eustatic falls of 25 m that were associated with two large 0 75 deep sea 18 o increases 92 93 ma mid turonian and 96 ma mid cenomanian we reconcile records of warm high latitudes with glacioeustasy by proposing that late cretaceous early eocene ice sheets generally reached maximum volumes of 8 12 10 6 km 3 20 30 m glacioeustatic equivalent but did not reach the antarctic coast hence coastal antarctica hence deep water remained relatively warm even though there were significant changes in sea level as the result of glaciation unlike the oligocene and younger icehouse world these ice sheets only existed during short intervals of peak milankovitch insolation leaving antarctica ice free during much of the greenhouse late cretaceous to middle eocene these results highlight the need to re evaluate the paradigm that polar ice sheets did not exist during times of warm high latitude climates

multiple early eocene hyperthermals their sedimentary expression on the new zealand continental margin and in the deep sea the paleocene eocene thermal maximum petm ca 55 5 ma was a geologically brief interval characterized by massive influx of isotopically light carbon extreme changes in global climate and profound variations in earth system processes an outstanding issue is whether it was an isolated event or the most prominent example of a recurring phenomenon recent studies of condensed deep sea sections support the latter but this finding remains uncertain here we present and discuss lithologic and carbon isotope records across two lower eocene outcrops on south island new zealand the petm manifests as a marl rich horizon with a significant negative carbon isotope excursion cie above in sediment deposited between 54 and 53 ma are four horizons with similar though less pronounced expressions marl beds of all five horizons represent increased terrigenous sedimentation presumably linked to an accelerated hydrological cycle five corresponding clay rich horizons and cies are found in deep sea records although the lithologic variations represent carbonate dissolution rather than siliciclastic dilution the presence of five intervals with similar systemic responses in different environments suggests a mechanism that repeatedly injected large masses of 13 c depleted carbon during the early eocene

a transient rise in tropical sea surface temperature during the paleocene eocene thermal maximum the paleocene eocene thermal maximum petm has been attributed to a rapid rise in greenhouse gas levels if so warming should have occurred at all latitudes although amplified toward the poles existing records reveal an increase in high latitude sea surface temperatures ssts 8 to 10 c and in bottom water temperatures 4 to 5 c to date however the character of the tropical sst response during this event remains unconstrained here we address this deficiency by using paired oxygen isotope and minor element magnesium calcium ratios of planktonic foraminifera from a tropical pacific core to estimate changes in sst using mixed layer foraminifera we found that the combined proxies imply a 4 to 5 c rise in pacific sst during the petm these results would necessitate a rise in atmospheric pco 2 to levels three to four times as high as those estimated for the late paleocene

long term and short term global cenozoic sea level estimates backstripping analysis of three continuously cored well dated boreholes from the new jersey coastal plain ocean drilling program odp leg 150x indicates a long term 10 8 n10 7 yr eustatic fall of 100 m since 55 ma early eocene and suggests short term 0 5n3 m y eustatic falls of less than 70 m eustatic estimates are calculated from residuals between the decompacted unloaded and paleodepth corrected records and tectonic subsidence assuming a cooling lithospheric plate because the residuals are similar among the three sites we interpret them as an approximation of the eustatic signal

environmental change across the paleocene eocene transition from eastern new zealand a marine palynological approach abstract recent improvements in the resolution and calibration of dinoflagellate cyst dinocyst bioevents across the paleocene eocene p e transition in new zealand allow better understanding of the relation between dinocyst variations and environmental change in southern mid high latitudes during this greenhouse climate combining information from land spore pollen assemblages with coeval dinocyst records allows evaluation of plant changes in a marine based timeframe palynological associations at tawanui and moeraki hampden eastern new zealand fluctuate across the p e transition and local palynological phases are recognized the onset of major fluctuations in dinocyst assemblages coincide with the intense warmth and excess carbon of the initial eocene thermal maximum ietm changes in sea surface temperature sst appear to have been the main environmental factor that affected dinoflagellates short lived intervals of higher ssts suggested by a high relative abundance of the apectodinium complex are seen during the ietm and lower eocene abundant cysts of probable heterotrophic dinoflagellates suggest surface waters remained relatively eutrophic for up to 0 5 myr after the onset of the ietm perhaps in response to enhanced terrigenous input related to changes in the character and pattern of continental weathering in contrast to dinocysts spore pollen assemblages suggest plant communities remained rather stable across the p e transition vegetation was dominated by a mesothermal conifer dominated multistratal rainforest and low latitude nypa mangroves were established by the uppermost paleocene plants in this region show no clear response to the ietm and the predominant vegetation change may have occurred at least 1 5 myr later characterized by an increase in mesothermal megathermal angiosperm plants

a coupled climate ice sheet modeling approach to the early cenozoic history of the antarctic ice sheet abstract the sudden widespread glaciation of antarctica and the associated shift toward colder temperatures near the eocene oligocene boundary 34 ma represents one of the most fundamental reorganizations of the global climate system recognized in the geologic record this glacial inception and the subsequent evolution of the early east antarctic ice sheet eais are simulated using a new coupled global climate dynamical ice sheet model accounting for the paleogeography greenhouse gas concentrations changing orbital parameters and varying ocean heat transport suites of long 105 yr climate ice sheet simulations are used to investigate the effects of declining atmospheric co2 compared to those of the tectonic opening of southern ocean gateways and the timing of mountain uplift in the antarctic interior in contrast to the established paradigm for the glaciation of antarctica which centers on the opening of the southern ocean gateways and the thermal isolation of the continent our results show that declining cenozoic pco2 may have played the dominant role first small isolated ice caps formed on the highest antarctic plateaus then as a co2 threshold between 3 and 2 pre industrial level pal was crossed height mass balance feedbacks were initiated during orbital periods with cold austral summers triggering much larger highly dynamic terrestrial ice sheets as co2 continued to decline these isolated ice caps eventually merged into a permanent continental scale eais in our model neither the opening of the southern ocean gateways nor mountain uplift significantly affected the timing of the major ice sheet transition given a scenario of gradually declining co2 from 4 to 2 pal over 10 million years around the eocene oligocene boundary

release of methane from a volcanic basin as a mechanism for initial eocene global warming a 200 000 yr interval of extreme global warming marked the start of the eocene epoch about 55 million years ago negative carbon and oxygen isotope excursions in marine and terrestrial sediments show that this event was linked to a massive and rapid approximately 10 000 yr input of isotopically depleted carbon it has been suggested previously that extensive melting of gas hydrates buried in marine sediments may represent the carbon source and has caused the global climate change large scale hydrate melting however requires a hitherto unknown triggering mechanism here we present evidence for the presence of thousands of hydrothermal vent complexes identified on seismic reflection profiles from the voring and more basins in the norwegian sea we propose that intrusion of voluminous mantle derived melts in carbon rich sedimentary strata in the northeast atlantic may have caused an explosive release of methane transported to the ocean or atmosphere through the vent complexes close to the palaeocene eocene boundary similar volcanic and metamorphic processes may explain climate events associated with other large igneous provinces such as the siberian traps approximately 250 million years ago and the karoo igneous province approximately 183 million years ago