precessional climate cyclicity in late cretaceous early tertiary marine sediments a high resolution chronometer of cretaceous tertiary boundary events we report well dated late cretaceous and early tertiary precessional climatic cycles recorded by rhythmic carbonate maxima and minima in south atlantic deep sea sites spectral analyses of digitized sediment color a suitable carbonate proxy show prominent regularities in the spacing marl carbonate beds magnetostratigraphic dating over a number of magnetic chrons constrains the duration of the cycles which can be detected over at least 20 myr of sedimentation at 7 coring locations their mean absolute period of23 5 4 4kyr agrees closely with the predicted late cretaceous precessional period of 20 8 kyr because they can be matched to a physical forcing mechanism with a known repeat time the cycles offer a new high resolution tool to measure rates of climate change before and after the cretaceous tertiary k t boundary from counts of carbonate cycles we derive the position of the k t boundary within c29r at 350 kyr after the base of the reversal the constancy of cycle thickness linearly related to sedimentation rate and amplitude up to the boundary clay does not give evidence for climate instability preceding the boundary orbital chronometry records a step function decrease in sediment accumulation rate at the cretaceous tertiary boundary that is consistent with a geologically instantaneous event

intercalibration of astronomical and radioisotopic time the 40ar 39ar radioisotopic dating technique is one of the most precise and versatile methods available for dating events in earth s history but the accuracy of this method is limited by the accuracy with which the ages of neutron fluence monitors dating standards are known calibrating the ages of standards by conventional means has proved difficult and contentious the emerging astronomically calibrated geomagnetic polarity time scale apts offers a means to calibrate the ages of 40ar 39ar dating standards that is independent of absolute isotopic abundance measurements seven published 40ar 39ar dates for polarity transitions nominally ranging from 0 78 to 3 40 ma are based on the fish canyon sanidine standard and can be compared with apts predictions solving the 40ar 39ar age equation for the age of the fish canyon sanidine that produces coincidence with the apts age for each of these seven reversals yields mutually indistinguishable estimates ranging from 27 78 to 28 09 ma with an inverse variance weighted mean of 27 95 0 18 ma normalized residuals are minimized at an age of 27 92 ma indicating the robustness of the solution

littoral landforms and pedosedimentary sequences indicating late holocene lake level changes in northern central europe a case study from northeastern germany abstract a multidisciplinary study was carried out at lake groser furstenseer see lfs in order to explore the potential of littoral sediments palaeosols and landforms as indicators of historical lake level changes this research was initiated to investigate the extent to which lakes in northern central europe responded hydrologically to climatic and land use changes in the last millennium specific landforms investigated comprise lake terraces beach ridges local basins peatlands and dunes revealing a wealth of sedimentary sub environments at the lakeshore eleven sections were recorded with subsequent sedimentological pedological geochronological osl 14c and palaeobotanical pollen macro remains analyses most of the pedosedimentary littoral sequences show a succession of basal glacial sand intermediate palaeosols and lacustrine sand on top a broader number of semi terrestrial buried palaeosols along the lakeshore were systematically identified and analysed providing evidence for changing hydrological conditions during the late holocene additional historical data from the last centuries e g maps aerial photos public records allow the lake levels reconstructed from geoarchives to be connected with modern gauging data all local data sources available enable a tracing of lake level changes of the lfs during the last millennium comprising periods of relatively low c 1200 ad 2000s ad and relatively high water levels c 1250 1450 ad c 1780 ad 1980s ad the amplitude of lake level changes during the last c 1000 years amounts to c 3 m so that the fluctuations of the last 30 years recorded by lake level monitoring only reflect a small amount of the potential variability regional climate and local land use history suggest that the medieval lake level dynamics of lfs were primarily governed by climate and secondarily influenced by human impact on the drainage system at present the lake level is additionally influenced by the impact of highly water consuming pine plantations in the catchment area the regional significance of the local development at lfs can be demonstrated by comparison with other regional and supra regional lake level data the present study underlines the potential of a closer examination of the littoral zone for lake level reconstructions with high altitudinal precision

role of plutonism in low pressure metamorphic belt formation wickham and oxburgh1 recently proposed that low pressure high temperature low p high t metamorphism in the eastern pyrenees and possibly all low p high t metamorphic belts resulted from anomalously high mantle heat flow brought about by rifting their model is largely constrained by the presence of nearby synmetamorphic rift related sedimentary rocks and the interpretation that the migmatites and granites are the product of in situ melting in the presence of an anomalously steep geotherm here we present an alternative model in which low p high t metamorphism pro grade reactions at pressures near or below the al2sio5 triple point results from contact effects near sill like igneous intrusions at intermediate crustal levels low p high t conditions can be achieved through this process in regions of continent continent collision with normal mantle heat flux as well as in zones of extension our model is based on studies of the low p high t metamorphic terrane in the new england appalachians

astronomical duration of polarity chron c31r lower maastrichtian cyclostratigraphy of odp site 762 indian ocean and the contessa highway section gubbio italy the duration of polarity chron c31r is estimated with a cyclostratigraphic approach two sites are investigated odp site 762 indian ocean and the contessa highway section gubbio italy cyclostratigraphic analysis is performed on greyscale variations site 762 and magnetic susceptibility variations contessa section both sites reveal an astronomical control of the sedimentation highlighted by the identification of all the orbital periodicities cyclostratigraphic signals are tuned on 405 ka eccentricity cycles extracted from the la04 astronomical solution in both sites cycle counting gives an estimate of the duration of polarity chron c31r of about 2 09 0 03 ma

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

sand drift and soil formation along an exposed north atlantic coastline 14 000 years of diverse geomorphological climatic and human impacts this paper sets out the history of aeolian deposition and soil formation over the last 14 15 000 calendar years along the exposed and gale prone atlantic coastlines of the southern isles of the outer hebrides of scotland detailed palaeoenvironmental interpretation and chronological control have been provided by field mapping soil micromorphological analyses and radiocarbon and optically stimulated luminescence osl dating programmes two dominant types of aeolian sands are described in this region quartzose sands are shown to originate mainly as periglacial wind blown sands derived from glacial and periglacial deposits of late devensian age which were formerly exposed on the present continental shelf this aeolian deposition did however continue into the early holocene with re working perhaps by slope wash taking place as recently as the 4th millenniumbp quartzose sands mantle valley floors and hillslopes by the end of the devensian and early holocene a variety of soil types with extensive horizonation had developed upon them including podzolic brown earths peaty gleys and peat soils radiocarbon and osl dating demonstrate that the carbonate sands of the machair sand sheets which characterize the present atlantic shorelines began to accumulate very early for a european shoreline from approximately 8700 calendar years ago on benbecula and north uist whereas further south deposition began later osl dating suggests that non sequences and diastems are common in greater part these machair sand sheets are best interpreted as a composite of separate slivers of sand reflecting small scale and local episodes of sand drift rather than distinct layers of region wide distribution which might reflect past major storms or significant palaeoclimatic fluctuations the new evidence presented here provides little support for the following explanatory geomorphic or stratigraphic models which have previously sought to explain the development of these coastal machair landscapes continuous development layer cake or step wise prograding coastal barrier qualified support is given for the explanations that emphasize i the long term spasmodic input and re cycling of sands and ii that the present smoothed landscapes and distinctive machair grassland vegetation are essentially recent in age and reflect the interactions of natural and human processes in a stormy environment characterized by re working widespread layers of thick organic materials within the carbonate sands in the study area which have previously been regarded as dune palaeosols dating to the bronze age and iron age are suggested by soil micromorphological analysis to be in significant part anthropogenic in origin they are organically enriched layers or midden soils the consequence of human activities notably the disposal of organic wastes and other forms of soil modification during times of significant settlement in these coastal sands these periods of relatively intense human activity are therefore shown to be associated at least locally with periods of soil formation and stability not universal instability and dune drift along these shorelines in general these extensive layers of midden soil do not necessarily imply periods of decreased storminess relatively widespread soil formation in these coastal dunes did however take place in the period between 400 and 100 years ago essentially within the period of increased storminess associated with the little ice age it is suggested that at some point s within the following periods of time broadly defined in calendar yearsbp notable sand drift affecting the quartzose sands the carbonate sands or both took place within the study area 13 700 13 000 11 000 10 500 9000 8300 7500 7000 6900 6400 5800 4200 one of the most notable episodes of drift in the outer hebrides as well as elsewhere on the coast of north west europe 3800 3300 1700 1300 600 200 with individual great storms being recorded in the 17th and 18th centuries and 100 present day limited drift associated with machair stratification

astronomical calibration of the maastrichtian late cretaceous abstract recent improvements to astronomical modeling of the solar system have contributed to important refinements of the cenozoic time scale through astronomical calibration of sedimentary series we extend this astronomical calibration into the cretaceous on the base of the 405 ka orbital eccentricity variation thanks to the recovery of well preserved maastrichtian sedimentary series from odp ocean drilling program holes 1258a leg 207 equatorial atlantic 1267b leg 208 south atlantic 762c leg 122 indian ocean and dsdp deep sea drilling program hole 525a leg 74 south atlantic cyclostratigraphic analysis is performed on high resolution measurements of magnetic susceptibility on sediments cored during legs 207 and 208 and gray level variations of sediment color obtained from core photographs from legs 122 and 74 astronomical control on sedimentation is evident at every site with the presence of cycles corresponding to forcing by precession obliquity and orbital eccentricity variations identification of these cycles leads to the definition of a detailed cyclostratigraphic frame covering nearly 8 ma from the upper campanian to the cretaceous paleogene k pg boundary durations of each magnetochron from c32r 2r to c29n are inferred by cycle counting astronomical calibrations of maastrichtian sedimentary series are proposed based on the 405 ka eccentricity variation according to the most recent astronomical solution la2010a two different ages are suggested for the k pg boundary considering the uncertainty of the long term variation of the 405 ka eccentricity cycle the first proposal provides a cretaceous paleogene boundary age of 65 59 0 07 ma and the second an age of 66 0 07 ma which is coherent with the most recent radio isotopic datings magnetochron boundaries and the campanian maastrichtian boundary are dated relative to these numerical ages of the k pg boundary

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

closing the mid palaeocene gap toward a complete astronomically tuned palaeocene epoch and selandian and thanetian gssps at zumaia basque basin w pyrenees abstract an integrated magneto bio and cyclostratigraphic framework is presented for the mid palaeocene interval from the hemi pelagic sea cliff section of zumaia in the basque basin the new 55 m long studied section expands about 3 5 myr and closes the gap between previously published integrated studies in the section the occurrence of magnetochron c26n is now documented and its duration complemented also by data from the ibaeta section and that for chrons c26r and c25r is estimated by counting precession related lithologic couplets assigned to have 21 kyr duration c25r 1449 kyr c26n 231 kyr c26r 2877 kyr consequently the zumaia section now provides the first complete palaeocene astronomically derived chronology rendering this section a master reference section due to limitations in the orbital calculations and uncertainties in the radiometric dating method no robust tuning and absolute ages can be given for the moment however the fos first occurrences of key calcareous plankton species and the mid palaeocene biotic event mpbe are placed within the magnetostratigraphic and cyclostratigraphic template along the studied mid palaeocene interval in addition the dataset provides the key elements for a proper settling of the thanetian and selandian global stratotype section and point gssps which is one of the primary objectives of the ics international commission of stratigraphy we consider the base of chron c26n and the criteria associated to the lithostratigraphic change between the danian limestone fm and the itzurun marl fm at zumaia as the respective delimiting points for the thanetian and selandian bases as recently agreed by the paleocene working group of the international subcommission of the paleogene stratigraphy of the ics consequently the duration of the thanetian selandian and danian component stages can be estimated at zumaia to be about 3129 kyr 2163 kyr and 4324 kyr respectively see text for error considerations however the mpbe located 8 precession cycles below the base of c26n in correspondence to a short eccentricity maxima at zumaia could also serve as a guiding criteria to approximate or redefine the thanetian base if this level demonstrated synchronous

latest paleocene earliest eocene cyclostratigraphy using core photographs for reconnaissance geophysical logging abstract i present a new method for reconnaissance cyclostratigraphic study of continuously cored boreholes the generation of detailed sediment color logs by digitizing ocean drilling program odp core photographs the reliability of the method is tested by comparison with the spectrophotometer color log for the uppermost paleocene lowermost eocene section chron c24r at odp hole 1051a the color log generated from hole 1051a core photographs is essentially identical to the spectrophotometer log the method is applied to the chron c24r section at holes 1051a and 690b producing the first high resolution geophysical log for the latter section i calculate astronomically calibrated durations between bio and chemostratigraphic events within chron c24r by correlating the cyclostratigraphies for holes 1051a and 690b these durations are significantly different from previous estimates indicating that the chronology of events surrounding the paleocene eocene boundary will have to be revised this study demonstrates that useful geophysical logs can be generated from digitized odp and dsdp core photographs the method is of practical use for sections lacking high resolution logs as is the case for most lower paleogene sections

extending the astronomical polarity time scale into the miocene an astronomical time scale is presented for the late miocene based on the correlation of characteristic sedimentary cycle patterns in marine sections in the mediterranean to the 65 n summer insolation curve of la90 1 2 with present day values for the dynamical ellipticity of the earth and tidd dissipation by the moon this correlation yields ages for all sedimentary cycles and hence also for the recorded polarity reversals and planktonic foraminiferal and dinoflagellate events the tortonian messinian t m boundary placed at the first regular occurrence of the globorofuliu conomiozea group in the mediterranean is dated at 7 24 ma the duration of the messinian is estimated at 1 91 myr because the miocene pliocene boundary has been dated previously at 5 33 ma 3 the new time scale is confirmed by oar 3gar ages of volcanic beds and by the number of sedimentary cycles in the younger part of the mediterranean messinian

a blast of gas in the latest paleocene simulating first order effects of massive dissociation of oceanic methane hydrate carbonate and organic matter deposited during the latest paleocene thermal maximum is characterized by a remarkable 2 5 excursion in delta 13c that occurred over approximately 10 4 yr and returned to near initial values in an exponential pattern over approximately 2 x 10 5 yr it has been hypothesized that this excursion signifies transfer of 1 4 to 2 8 x 10 18 g of ch4 from oceanic hydrates to the combined ocean atmosphere inorganic carbon reservoir a scenario with 1 12 x 10 18 g of ch4 is numerically simulated here within the framework of the present day global carbon cycle to test the plausibility of the hypothesis we find that 1 the delta 13c of the deep ocean shallow ocean and atmosphere decreases by 2 3 over 10 4 yr and returns to initial values in an exponential pattern over approximately 2 x 10 5 yr 2 the depth of the lysocline shoals by up to 400 m over 10 4 yr and this rise is most pronounced in one ocean region and 3 global surface temperature increases by approximately 2 degrees c over 10 4 yr and returns to initial values over approximately 2 x 10 6 yr the first effect is quantitatively consistent with the geologic record the latter two effects are qualitatively consistent with observations thus significant ch4 release from oceanic hydrates is a plausible explanation for observed carbon cycle perturbations during the thermal maximum this conclusion is of broad interest because the flux of ch4 invoked during the maximum is of similar magnitude to that released to the atmosphere from present day anthropogenic ch4 sources

astronomical calibration of the paleocene time the first complete cyclic sedimentary successions for the early paleogene from drilling multiple holes have been retrieved during two odp expeditions leg 198 shatsky rise nw pacific ocean and leg 208 walvis ridge se atlantic ocean these new records allow us to construct a comprehensive astronomically calibrated stratigraphic framework with an unprecedented accuracy for both the atlantic and the pacific oceans covering the entire paleocene epoch based on the identification of the stable long eccentricity cycle 405 kyr high resolution x ray fluorescence xrf core scanner and non destructive core logging data from sites 1209 through 1211 leg 198 and sites 1262 1267 leg 208 are the basis for such a robust chronostratigraphy former investigated marine odp sites 1001 and 1051 and land based e g zumaia sections have been integrated as well the high fidelity chronology is the prerequisite for deciphering mechanisms in relation to prominent transient climatic events as well as completely new insights into greenhouse climate variability in the early paleogene we demonstrate that the paleocene epoch covers 24 long eccentricity cycles we also show that no definite absolute age datums for the k pg boundary or the paleocene eocene thermal maximum petm can be provided by now because of still existing uncertainties in orbital solutions and radiometric dating however we provide two options for tuning of the paleocene which are only offset by 405 kyr our orbitally calibrated integrated leg 208 magnetostratigraphy is used to revise the geomagnetic polarity time scale gpts for chron c29 to c25 we established a high resolution calcareous nannofossil biostratigraphy for the south atlantic which allows a much more detailed relative scaling of stages with biozones the re evaluation of the south atlantic spreading rate model features higher frequent oscillations in spreading rates for magnetochron c28r c27n and c26n

a salt oscillator in the glacial atlantic 1 the concept as shown by the work of dansgaard and his colleagues climate oscillations of one or so millennia duration punctuate much of glacial section of the greenland ice cores these oscillations are characterized by 5 c air temperature changes severalfold dust content changes and 50 ppm co2 changes both the temperature and co2 change are best explained by changes in the mode of operation of the ocean in this paper we provide evidence which suggests that oscillations in surface water conditions of similar duration are present in the record from a deep sea core at 50 n based on this finding we suggest that the greenland climate changes are driven by oscillations in the salinity of the atlantic ocean which modulate the strength of the atlantic s conveyor circulation

the bronze age landscape of the bjare peninsula southern sweden and its relationship to burial mounds palaeoecological analyses from a small fen deposit combined with pollen analysis from buried soil profiles under prehistoric burial mounds have been used to investigate the timing and vegetation change associated with the holocene development of a cultural landscape in southern sweden traditional pollen analysis is complemented with plant macrofossil analysis and soil pollen analysis from within and in close proximity to the burial mounds in the coastal bjare peninsula well known for its high density of well preserved bronze age monuments the vegetation development is linked to the construction of the burial mounds a marked increase of cultural impact on the landscape is recorded during the neolithic bronze age transition and estimates of landscape openness suggest that by the onset of the bronze age forest cover was only 20 40 falling to 10 in the immediate vicinity of the burial mounds themselves the coastal strip appears to have been affected by human activity to a greater extent and at an earlier date than sites from further inland in southern sweden and the bronze age burial mounds were most likely designed to be visible in a largely deforested landscape

potential of cone penetrating testing for mapping deeply buried palaeolandscapes in the context of archaeological surveys in polder areas geoarchaeological mapping of wetlands conventionally involves extensive coring especially in wetlands marked by a deep palaeosurface 3 m deep this can be very difficult and time consuming in this paper we therefore present an alternative approach based on cone penetration testing cpt for structured rapid and cost effective evaluation of buried palaeolandscapes both estuarine and river floodplain environments were investigated including the water land transition zone marsh the efficiency reliability and repeatability of the cpt method was tested through the comparison with ground truth core data the cpt data generally allowed highly accurate mapping of the palaeotopography of the prehistoric surfaces and the overlying peat sequences thin organic rich clay intercalations within the peat layers could often still be identified additional pore pressure conductivity and seismic velocity data from cpt u cpt c and s cpt did not add much crucial information and their main use seems to lie in the added value for near surface geophysical measurements the results of this research clearly illustrate the importance of cpt information for mapping of palaeolandscapes in archaeology

a new geomagnetic polarity time scale for the late cretaceous and cenozoic we have constructed a magnetic polarity time scale for the late cretaceous and cenozoic based on an analysis of marine magnetic profiles from the world s ocean basins this is the first time since heirtzler et al 1968 published their time scale that the relative widths of the magnetic polarity intervals for the entire late cretaceous and cenozoic have been systematically determined from magnetic profiles a composite geomagnetic polarity sequence was derived based primarily on data from the south atlantic anomaly spacings in the south atlantic were constrained by a combination of finite rotation poles and averages of stacked profiles fine scale information was derived from magnetic profiles on faster spreading ridges in the pacific and indian oceans and inserted into the south ariantic sequence based on the assumption that spreading rates in the south atlantic were smoothly varying but not necessarily constant a time scale was generated by using a spline function to fit a set of nine age calibration points

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

the importance of independent chronology in integrating records of past climate change for the 60 8 ka intimate time interval this paper provides a brief overview of the most common dating techniques applied in palaeoclimate and palaeoenvironmental studies including four radiometric and isotopic dating methods radiocarbon 230th disequilibrium luminescence cosmogenic nuclides and two incremental methods based on layer counting ice layer varves for each method concise background information about the fundamental principles and methodological approaches is provided we concentrate on the time interval of focus for the intimate integrating ice core marine and terrestrial records community 60 8 ka this dating guide addresses palaeoclimatologists who aim at interpretation of their often regional and local proxy time series in a wider spatial context and therefore have to rely on correlation with proxy records obtained from different archives from various regions for this reason we especially emphasise scientific approaches for harmonising chronologies for sophisticated and robust proxy data integration in this respect up to date age modelling techniques are presented as well as tools for linking records by age equivalence including tephrochronology cosmogenic 10be and palaeomagnetic variations finally to avoid inadequate documentation of chronologies and assure reliable correlation of proxy time series this paper provides recommendations for minimum standards of uncertainty and age datum reporting

new chronology for the late paleocene thermal maximum and its environmental implications the late paleocene thermal maximum lptm is associated with a brief but intense interval of global warming and a massive perturbation of the global carbon cycle we have developed a new orbital chronology for ocean drilling program odp site 690 weddell sea southern ocean by using spectral analysis of high resolution geochemical records the lptm interval spans 11 precessional cycles yielding a duration of 210 to 220 k y the 13 c anomaly associated with the lptm has a magnitude of about 2 5 to 3 we show that about 2 of the excursion occurs within two steps that each were less than 1000 yr in duration the remainder developed through a series of steps over 52 k y the timing of these steps is consistent with a series of nearly catastrophic releases of methane from gas hydrates punctuated by intervals of relative equilibria between hydrate dissociation and carbon burial further we are able to correlate the records between odp sites 690 and 1051 western north atlantic on the scale of 21 k y cycles which demonstrates that the details of the 13 c excursion are recognizable between distant sites comparison of cycle records at sites 690 and 1051 suggests that sediment representing the interval 30 k y just prior to and at the onset of the lptm are missing in the latter location this unconformity probably resulted from slope failure accompanying methane hydrate dissociation within 10 k y of the start of the lptm

changes in calcareous nannofossil assemblages across the paleocene eocene transition from the paleo equatorial pacific ocean quantitative analyses of selected calcareous nannofossils in deep sea sections recovered from the paleo equatorial pacific odp leg 199 provide new information about biostratigraphy biochronology and the evolutionary history of calcareous nannofossils across the paleocene eocene transition interval the sediment cores from odp leg 199 represent the first continuous paleocene eocene boundary sections ever to be sampled in the central equatorial pacific ocean calcareous nannofossil assemblages are studied to document the distribution of biostratigraphically useful taxa such as ericsonia discoaster fasciculithus rhomboaster and tribrachiatus focus is given to the evolution of the rhomboaster tribrachiatus lineage in the lower eocene interval at site 1215 and on the stratigraphic relationship of these taxa relative to species in the genus fasciculithus critical intervals of north atlantic dsdp site 550 have also been re examined the tribrachiatus digitalis morphotype was described at site 550 from an interval affected by down hole contamination partly originating from within the tribrachiatus orthostylus range the t digitalis morphotype represents an evolutionary transitional form between t contortus and t orthostylus entering the stratigraphic record within the range of the former species and disappearing within the lower part of the range of the latter species the subzonal subdivision of zone np10 hence collapses lithological and colour variability reflecting orbital cyclicity occur in the lower eocene of site 1215 permitting a relative astronomical age calibration of the tribrachiatus taxa the distinct rhomboaster spp discoaster araneus association also occurs in the paleo equatorial pacific ocean together with a marked decrease in diversity of fasciculithus spp site 1220 reveals a short peak abundance of thoracosphaera spp just above the p e boundary interval which probably reflects a stressed surface water environment

palaeosols in saharan and sahelian dunes of chad archives of holocene north african climate changes limnic sediments and palaeosols are frequently present in dunes of the sahara and sahel deserts of chad this study focused on genesis and degree of development of the palaeosols and the timing of soil formation the soils are cambic arenosols formed by precipitation induced silicate weathering and leaching the upper parts of the cambic arenosols are indurated due to accumulation of salt and amorphous silica during a drier climate following soil formation the optical age data reveal the occurrence of one or two distinct short lived humid climate intervals shortly after 5 ka and before 2 5 ka and the formation of local desert lakes shortly after 5 ka the study further suggests that rapid climate changes occurred mainly in the mid holocene whereas the early holocene humid period lasted longer

pleistocene paleosols in norway implications for past climate and glacial erosion abstract as recently as 7 years ago quaternary geologists believed that there were no pleistocene paleosols represented by non peaty soil horizons a b etc in norway however several buried soils of this type have recently been reported and studied by stratigraphic magnetic and chemical methods magnetic susceptibility is a useful method for identifying and correlating paleosols even in areas of complex glacial stratigraphy such as the nordic countries at sargejohka in finnmark up to seven different buried pedocomplexes are separated by tills and glaciotectonic deformation structures they represent different periods of land surface stability and with two possible exceptions are not pseudosoils formed by a fluctuating groundwater table the most important from stratigraphic and paleoclimatic points of view is a well developed red yellow paleosol numbered p3 counting down from the top it is thought to be a podzol of the last interglacial later cryoturbation of pre mid weichselian age has greatly altered its upper part indicating a dramatic change in climate after development of the soil at lillehammer in southeastern norway remains of the oxidised zone of a buried paleosol also thought to have formed mainly in the last interglacial occur in an inferred saalian till the presence of buried pleistocene paleosols in the interior of norway central part of the fennoscandian glaciations indicates that glacial erosion was locally less during several glacial cycles than previously thought

slope deposits as an indicator of anthropopressure in the light of research in central poland abstract results of research on neo holocene slope covers uncovered at archaeological sites in central poland are described in this paper geoarchaeological investigations have been undertaken in the ner river basin distinctive archaeological relicts of human activity document periods of intensive activity of human societies artefacts included within deposits play a very important role in correct recognition of the chronology of covers and ecofacts for reconstructions of environmental evolution the origin and development of slope covers have been correlated with anthropogenic changes of the natural environment two main phases of acceleration of slope processes have been recognised dated to the middle bronze age and to the late roman period slope deposits have been classified as deluvia deluvial slope wash deposits or colluvial deposits their features are most typical for deluvial sands and if they contain more humic matter for soil deluvia the deluvial covers have been deposited as an effect of moderately intensive slope wash processes accumulation of slope deposits has resulted from natural processes initiated by human impact during periods of intensive settlement and economic activity the slope cover sediments are the source for recognition of intensity of human impact and of economic activity of ancient societies and for distinct phases of hiatuses of settlement development the possibility of archaeological and palaeogeographical interpretations based on research on slope covers at archaeological sites is presented

orbitally paced climate oscillations across the oligocene miocene boundary the late oligocene and early miocene periods some 21 to 27 million years ago have generally been viewed as times of moderate global warmth and ice free conditions yet several lines of evidence suggest that this interval was punctuated by at least one and possibly several episodes of high latitude cooling and continental glaciation1 2 3 here we present stable isotope and per cent coarse fraction data from an equatorial western atlantic deep sea sediment core that provide high resolution records of the climate variability across the oligocene miocene transition 22 5 25 7 million years ago a strong 40 kyr periodicity in the oxygen isotope record is consistent with a high latitude orbital obliquity control on ice volume and temperature orbital influences are also apparent at precession and eccentricity frequencies including a series of 400 kyr oscillations that culminate in distinct maxima at the oligocene miocene boundary about 23 7 million years ago covariance between the carbon and oxygen isotope records suggests that the oceanic carbon cycle may have contributed to global cooling during the 400 kyr cycles particularly at the oligocene miocene boundary

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

an alternative age model for the paleocene eocene thermal maximum using extraterrestrial 3he a continuous age model for the brief climate excursion at the paleocene eocene boundary has been constructed by assuming a constant flux of extraterrestrial 3he 3he et to the seafloor 3he et measurements from odp site 690 provide quantitative evidence for the rapid onset few kyr and short duration 120 kyr of global warming and of the associated disturbance to the earth s surficial carbon budget at this time these observations support astronomically calibrated age models indicating extremely rapid release of isotopically light carbon possibly from seafloor methane hydrate as the proximal cause of the event however the 3he et technique indicates a previously unrecognized and extreme increase in sedimentation rate coincident with the return of climate proxies to pre event values the 3he et based age model thus suggests a far more rapid recovery from the climatic perturbation than previously proposed or predicted on the basis of the modern carbon cycle and so may indicate additional or accelerated mechanisms of carbon removal from the ocean atmosphere system during this period 3he et was also measured at odp site 1051 to test the validity of the site 690 chronology comparison of these data sets seems to require removal of several tens of kyr of sediment within the climatic excursion at site 1051 an observation consistent with sediment structures and previous age modeling efforts the site 1051 age model shows a 30 kyr period in which climate proxies return toward pre event values after which they remain invariant for 80 kyr if this rise represents the recovery interval identified at site 690 then the 3he et based age models of the two sites are in good agreement however alternative interpretations are possible and work on less disrupted sites is required to evaluate the reliability of the proposed new chronology of the climate excursion regardless of these details this work shows that the 3he et technique can provide useful independent evidence for the development and testing of astronomically calibrated age models

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

orbital climate forcing of δ13c excursions in the late paleocene early eocene chrons c24n c25n 1 high resolution stable carbon isotope records for upper paleocene lower eocene sections at ocean drilling program sites 1051 and 690 and deep sea drilling project sites 550 and 577 show numerous rapid 40 60 kyr duration negative excursions of up to 1 we demonstrate that these transient decreases are the expected result of nonlinear insolation forcing of the carbon cycle in the context of a long carbon residence time the transients occur at maxima in earth s orbital eccentricity which result in high amplitude variations in insolation due to forcing by climatic precession the construction of accurate orbital chronologies for geologic sections older than 35 ma relies on identifying a high fidelity recorder of variations in earth s orbital eccentricity we use the carbon isotope records as such a recorder establishing a robust orbitally tuned chronology for latest paleocene earliest eocene events moreover the transient decreases provide a means of precise correlation among the four sites that is independent of magnetostratigraphic and biostratigraphic data at the 105 year scale while the eccentricity controlled transient decreases bear some resemblance to the much larger amplitude carbon isotope excursion cie that marks the paleocene eocene boundary the latter event is found to occur near a minimum in the 400 kyr eccentricity cycle thus the cie occurred during a time of minimal variability in insolation the dominant mechanism for forcing climate change on 104 year scales we argue that this is inconsistent with mechanisms that rely on a threshold climate event to trigger the paleocene eocene thermal maximum since any threshold would more likely be crossed during a period of high amplitude climate variations

historical soil erosion by water in germany scales and archives chronology research perspectives abstract the published record of historical soil erosion by water in germany as deduced from dated slope deposits n 306 alluvial sediments n 120 and lake sediments is summarized in this paper the number of sediments investigated reflects the state of knowledge chronology of historical soil erosion and to a certain degree the intensity of the human impact on german landscapes during the holocene even though few data of calculated historical soil erosion intensities exist an estimation of historical soil erosion in germany combining the available data has been calculated soil erosion in germany occurred first locally during the early holocene probably triggered by climatic variability from the neolithic onward the record reflects the human impact according to agricultural land use the observed variability indicates phases of weaker and regained intensity of agricultural land use in germany few records characterise the early and middle bronze age ca 2000 1600 bc and the migration period and the early medieval times ca 400 1000 ad surprisingly for the roman emperor times ca 1 400 ad a decreasing number of soil sediments is recorded even when the data from southern germany is examined separately phases characterised by an increase in soil erosion were the late bronze age and pre roman iron age ca 1600 bc 1 ad the high and late medieval times ca 1000 1350 ad and the modern times ca 1500 ad until today some extraordinary heavy precipitation events late 18th early 19th first half of 14th century pre roman iron age topped the even high soil erosion intensities research gaps as well as potential for future research as derived from the available data are outlined

magnetostratigraphic and cyclostratigraphic calibration of a prospective palaeocene eocene stratotype at zumaia basque basin northern spain detailed magnetostratigraphic work at the palaeocene eocene boundary interval in the zumaia section has led to a precise delineation of the position of polarity chron c25n from 35 0 m or 35 7 m to 25 2 m below the base of the carbon isotopic excursion that marks the palaeocene eocene boundary this chronostratigraphic constraint suggests that the lithological carbonate marl couplets making up most of the studied section are the expression of orbital precession cycles and confirms the expanded and continuous nature of the section with mean sediment accumulation rates of 2 5 cm kyr 1 the new data render zumaia a unique land based marine section with available magnetostratigraphic data coupled to cyclostratigraphy the revised chronostratigraphic framework presented supports previous cyclostratigraphic calibration of the latest palaeocene geomagnetic timescale it should facilitate better assessment of the different chemobiostratigraphic events that span this critical interval as a consequence of past climate and oceanographic change consequently the zumaia section is proposed as a candidate global stratotype section and point gssp for the palaeocene eocene boundary

late quaternary landscape development at the margin of the pomeranian phase mis 2 near lake wygonin northern poland abstract in central europe late quaternary landscapes experienced multiple phases of geomorphologic activity in this study we used a combined geomorphological pedological sedimentological and palynological approach to characterize landscape development after the last glacial maximum lgm near lake wygonin in northern poland the pedostratigraphical findings from soil pits and drillings were extrapolated using ground penetrating radar gpr and electric resistivity tomography ert during the pomeranian phase glacial and fluvioglacial processes dominated the landscape near lake wygonin at the end of the glacial period periglacial processes became relevant and caused the formation of ventifacts and coversands containing coated sand grains at approximately 15 290 14 800 cal yr bp a small pond formed in a kettle hole profile bwi 2 the lacustrine sediments lack eolian sand components and therefore indicate the decline of eolian processes during that time the increase of juniperus and rock rose helianthemum in the pollen diagram is a prominent marker of the younger dryas at the end of the younger dryas a partial reshaping of the landscape is indicated by abundant charcoal fragments in disturbed lake sediments no geomorphologic activity since the beginning of the holocene is documented in the terrestrial and wetland archives the anthropogenic impact is reflected in the pollen diagram by the occurrence of rye pollen grains secale cereale and translocated soil sediments dated to 1560 1410 cal yr bp proving agricultural use of the immediate vicinity with the onset of land use gully incision and the accumulation of colluvial fans reshaped the landscape locally since 540 460 cal yr bp further gully incision in the steep forest tracks has been associated with the intensification of forestry outside of the gully catchments the weakly podzolized rubic brunic arenosols show no features of holocene soil erosion

modelling soil landscape genesis a time split approach for hummocky agricultural landscapes abstract here we present a scheme for modelling soil landscape development in hummocky agricultural landscapes of formerly glaciated terrains soil landscape development is regarded as discontinuous over time long term progressive soil development during the holocene was replaced abruptly by an intense period of regressive pedogenesis during the last 50 years which is deduced from published 137 cs data and catchment scale mass balances consequently our primary working hypothesis is that the recent soil pattern is mainly a result of human influence during the last 50 years the paradigm behind our approach is that we have to couple geological historical information with recent dynamics of relevant processes to understand soil landscape development spatially distributed erosion and sedimentation are the most important processes during that period the intensity and extent of these processes is however also a function of the spatial pattern of soils erodibility which evolved in the progressive period therefore we developed a time split modelling approach for the progressive period relevant pedogenic processes de carbonatization silicate weathering clay translocation have to be quantified by a spatially distributed coupled water flow and solute transport model based on reconstructed initial and upper boundary conditions geomorphic units climate history relevant outputs e g topsoil textural properties are used as a spatially distributed input for the model of the regressive period for the latter we use a modified version of the dynamic physically based erosion 3d model schmidt j von werner m michael a 1996 erosion 2d 3d a computer model to simulate water erosion in german sachsische landesanstalt fur landwirtschaft dresden which allows spatially distributed modelling of water related soil erosion and deposition relevant topsoil properties are iteratively adapted to the rates of spatially distributed erosion and deposition preliminary results suggest that a coupling with tillage erosion plays an important role in our landscapes explicit analyses of the soil pattern using digital soil mapping techniques will be applied for model validation

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 history of soil erosion and fluvial deposits in small catchments of central europe deciphering the long term interaction between humans and the environment a review abstract during the last few decades many case studies focused on the dynamics of fluvial systems in response to hillslope erosion land use impact and climate changes this paper will review the current state of knowledge of the dynamics of past soil erosion and gullying in small catchments

global implications of lower to middle eocene sequence boundaries on the new jersey coastal plain the icehouse cometh wedocumentninelower middleeocenesequencesonthenewjerseycoastalplainand comparethemwithglobal d 18 oandhaqetal records earlyeocenehiatusesdonotmatch d 18 ochanges anditisunlikelythattheyaretheresultofglacioeustasy consistentwithan ice free early eocene early middle eocene 49 43 ma evidence for a link between sequencesand d 18 oisequivocal andthepresenceoflargeicesheetsisuncertain beginning in the late middle eocene 43 42 ma concomitant increases in planktonic and benthic d 18 o records coincide with the timing of hiatuses on the new jersey coastal plain and a change from carbonate dominated to siliciclastic dominated sedimentation these represent the development of the antarctic ice cap and the beginning of the icehouse world of the 14 sequences predicted by haq et al for this interval 9 are resolvable on the new jersey margin and the other 5 appear to be combined with others we conclude that although ice volume changes controlled sequences since at least 42 ma mechanisms for sea level change prior to then are still not fully understood

the source and fate of massive carbon input during the latest paleocene thermal maximum lithologic faunal seismic and isotopic evidence from the blake nose subtropical western north atlantic links a massive release of biogenic methane 55 5 million years ago to a warming of deep ocean and high latitude surface waters a large perturbation in the combined ocean atmosphere carbon cycle the largest of the past 90 million years a mass extinction event in benthic faunas and a radiation of mammalian orders the deposition of a mud clast interval and seismic evidence for slope disturbance are associated with intermediate water warming massive carbon input to the global exogenic carbon cycle pelagic carbonate dissolution a decrease in dissolved oxygen and a benthic foraminiferal extinction event these events provide evidence to confirm the gas hydrate dissociation hypothesis and identify the blake nose as a site of methane release

astronomical calibration of upper campanian maastrichtian carbon isotope events and calcareous plankton biostratigraphy in the indian ocean odp hole 762c implication for the age of the campanian maastrichtian boundary abstract an integrated framework of magnetostratigraphy calcareous microfossil bio events cyclostratigraphy and 13c stratigraphy is established for the upper campanian maastrichtian of odp hole 762c exmouth plateau northwestern australian margin bulk carbonate 13c events and nannofossil bio events have been recorded and plotted against magnetostratigraphy and provided absolute ages using the results of the cyclostratigraphic study and the recent astronomical calibration of the maastrichtian thirteen carbon isotope events and 40 nannofossil bio events are recognized and calibrated with cyclostratigraphy as well as 14 previously published foraminifer events thus constituting a solid basis for large scale correlations results show that this site is characterized by a nearly continuous sedimentation from the upper campanian to the k pg boundary except for a 500 kyr gap in magnetochron c31n correlation of the age calibrated 13c profile of odp hole 762c to the 13c profile of the tercis les bains section global stratotype section and point of the campanian maastrichtian boundary cmb allowed a precise recognition and dating of this stage boundary at 72 15 0 05 ma this accounts for a total duration of 6 15 0 05 ma for the maastrichtian stage correlation of the boundary level with northwest germany shows that the cmb as defined at the gssp is 800 kyr younger than the cmb as defined by belemnite zonation in the boreal realm odp hole 762c is the first section to bear at the same time an excellent recovery of sediments throughout the upper campanian maastrichtian a precise and well defined magnetostratigraphy a high resolution record of carbon isotope events and calcareous plankton biostratigraphy and a cyclostratigraphic study tied to the la2010a astronomical solution this section is thus proposed as an excellent reference for the upper campanian maastrichtian in the indian ocean

palaeosols and their cover sediments of a glacial landscape in northern central europe spatial distribution pedostratigraphy and evidence on landscape evolution abstract knowledge of the distribution types and properties of buried soils i e palaeosols is essential in understanding how lowlands in northern central europe have changed over past millennia this is an indispensable requirement for evaluating long term human impact including soil erosion and land cover dynamics in the serrahn area 62 km2 a young glacial landscape representative for northeastern germany and part of the muritz national park 26 pedosedimentary sections were documented and analysed to this end a multiproxy approach was applied using pedology micromorphology geochronology and palaeoecology statistical and spatial analyses of c 5200 soil profiles of which 10 contain palaeosols show that buried soils cover an area of 5 7 km2 i e 9 of the area studied most palaeosols are cambisols arenosols and gleysols palaeosols are mainly covered by aeolian and colluvial sands as well as by lacustrine sands and peat radiocarbon and luminescence dating together with palynological and anthracological data reveal that former land surfaces were dominantly buried through erosion triggered by human activity in the late holocene in addition but to a clearly smaller extent lateglacial early holocene palaeosols and cover sediments occur following medieval clear cutting and intensive land use the study area is today again widely forested the high share of buried land surfaces detected here is expected to be representative for the hilly glacial landscapes even in the wider region i e in northern central europe and should be considered in soil mapping soil carbon budgeting and assessments of past human impact

impact of human land use on soils and landforms in cultural landscapes on aeolian sandy substrates maashorst se netherlands pollen analysis soil micromorphology and radiocarbon dating have been the main scientific tools to unlock palaeoecological information from palaeosols during the past decades in recent years the application of optically stimulated luminescence osl dating on polycyclic driftsand profiles and plaggic deposits has been shown to be of great added value to understand the geochronology of the evolution of soils and landforms on sandy substrates this paper presents the reconstruction of the evolution of cultural soils and landforms in the study area maashorst southern netherlands which is part of an extensive region in northwestern europe underlain by predominantly late glacial aeolian coversand deposits deforestation and soils acidification related to human land use started before 1750 bc based on radiocarbon dating sedentary agriculture already started around 1000 bc but osl dates indicate that the accumulation of plaggic deposits did not start before the late middle ages the reconstructed evolution of cultural soils and landforms is based on information of scattered palaeosols interpolated and extrapolated to a sequence of palaeo soil maps palaeopedological information is not included in regular soil maps because soil classifications are based on the diagnostic properties of actual soils and normally neglect relicts of preliminary steps in soil development this is convenient for agricultural applications but such soil maps are less useful for the presentation of long term soil development or as abiotical base for designs for restoration ecology the results of this study include interpretive maps produced in a geographical information system of the soil patterns around 1500 ad and 2000 bc based on the present soil map and the reconstruction of palaeoecological development during the late holocene the time sequence of these historical interpretive soil maps reflects the impact of human land use on soils and landforms

lateglacial soil paleocatena in inland dune area of the torun basin northern poland abstract the buried toposequence of soils paleocatena dated to the allerod interstadial has been researched in this work studies were carried at the katarzynka site located in the inland dune area of the torun basin northern poland paleosols developed on the slope dividing two glaciofluvial terraces and were buried under dune sands during the younger dryas ca 11100 bp uncal the paleocatena consists of weakly developed podzolic usselo soil at the upper slope gley podzolic soil at the lower slope and humus enriched gleysol at the bottom of the sequence in some parts the paleosol also has the morphology of the bwb horizon typical for the so called finow soil in the uppermost topographical position the buried soil mantle is eroded by wind activity and shows disturbances typical for periglacial conditions usselo and finow soils are usually considered to be marker stratigraphical horizons for lateglacial aeolian landscapes of western and central europe although their genesis and paleoenvironmental significance are still controversial the occurrence in paleocatena pattern and morphological chemical and micromorphological features indicate their pedogenic nature the podzolic usselo soil gley podzolic soil and gleysol show clear effects of soil forming and diagenetic processes varying along the buried slope the origin of bwb finow soil horizon seems to be a post burial process similar to illuvial lamellae formation masking the effects of former pedogenic features in all probability this process was preceded by alterations of soil morphology caused by permafrost development at the onset of the younger dryas immediately before burial the variety of soils forming the paleocatena is clear evidence of landscape diversity during the allerod

magnetostratigraphic reinvestigation of the palaeocene eocene boundary interval in hole 690b maud rise antarctica summary hole 690b drilled on maud rise near antarctica provides one of the most important palaeocene eocene boundary interval sections magnetostratigraphy plays a key role in dating palaeocene eocene boundary events but there are two problems with the published scheme in hole 690b the first concerns major mismatches of several magnetozones and biozones in the succession the second is an unexplained pervasive declination cluster which should not be present in these azimuthally unoriented piston cores to resolve these issues a palaeomagnetic reinvestigation was carried out on 98 specimens from 12 cores through the upper palaeocene middle eocene section in hole 690b the bulk of the samples carry an approximately uniformly directed magnetically hard component resulting in a declination cluster effectively identical to that of the earlier study the spurious magnetization can be explained either as an inward radial magnetization or as a core split overprint by estimating the extent of the overprint within each sample it has been possible to construct a filtered magnetostratigraphy for the section the result is that many of the magnetozone biozone mismatches are eliminated and the record of the 2 5 myr chron c24r which brackets the various events associated with the palaeocene eocene boundary is considerably cleaner it is not possible to define the upper and lower boundaries of this magnetochron so we recommend that the dating of the events within this section be based on the biostratigraphy only

evidence of an abrupt environmental disruption during the mid paleocene biotic event zumaia section western pyrenees an abrupt environmental disruption occurred in the photic zone and at the seafloor during the mid paleocene biotic event mpbe calcareous nannoplankton planktic foraminifer and benthic foraminifer assemblages at zumaia section western pyrenees underwent a rapid and remarkable transformation the major calcareous plankton assemblage changes suggest a shift from relatively cooler mesotrophic to warmer more oligotrophic conditions indicating a disturbed environment due to the warming of the ocean benthic foraminifer assemblages were also significantly affected by the mpbe diversity of the assemblages and buliminids show net decline and the low food and opportunistic taxa increase in abundance the reorganization of the planktic ecosystem possibly involved changes in the food flux type and quantity to the seafloor thus triggering changes in the benthic communities a 1 negative 13 c shift and a 30 carbonate content decrease are recorded in connection with the biotic event this suggests that during the mpbe as in the paleocene eocene thermal maximum petm an input of a large mass of isotopically depleted carbon into the ocean and atmosphere could have lowered the deep sea ph triggering a rapid shoaling of the lysocline and contributing to greenhouse warming the mpbe was short lived according to the counting of limestonemarl couplets the stratigraphic expression of precession cycles throughout the zumaia section the mpbe lasted for 52 53 k y with the core of the event representing 10 11 k y the zumaia section is the first land based locality in which the mpbe is recognized and described in detail due to its expanded character and excellent paleontological record this section may prove to be a global reference section for the study of this short lived event