transionospheric attenuation of 100 khz radio waves inferred from satellite and ground based observations 1 around fifty loran long range navigation transmitters in the northern hemisphere currently launch continuously pulsed 100 khz radio waves into the earth s atmosphere for marine navigation it is discovered that the 100 khz radio waves from the loran transmissions can be detected by the demeter satellite at an altitude of 660 km above the transmitters these novel electric field measurements in space enable the determination of the nocturnal transionospheric attenuation by comparison with ground based electric field measurements the electric field measurements on the satellite indicate that the nocturnal transionospheric attenuation of 100 khz radio waves from loran transmissions is equivalent to a nocturnal subionospheric attenuation of the 100 khz radio waves at a distance of 7 9 mm the radio waves exhibit an average subionospheric attenuation of 5 db mm and it is concluded that the nocturnal transionospheric attenuation of 100 khz radio waves is 35 45 db this result enables future space missions to quantify the intensity of lightning discharges associated with transient luminous events and terrestrial ray flashes

unusual braarudosphaera bigelowii and micrantholithus vesper enrichment in the early miocene sediments from the slovenian corridor a seaway linking the central paratethys and the mediterranean abstract during a stratigraphic survey of an early miocene sedimentary sequence outcropping in se slovenia an unusual enrichment of the calcareous nannoplankton assemblage with pentaliths pentagonal nannoliths consisting of five crystal units and showing radial symmetry was detected pentaliths were only abundant in a short interval which was sampled in detail the lithological composition of this interval was indistinguishable from that of the underlying and the overlying strata the composition of nannoplankton assemblages and distribution patterns of different taxa were studied mineral composition total calcite content and 13c values of chosen sediment samples were analysed as well the pentalith enriched strata were deposited in the lower early miocene corresponding to the egerian stage of the central paratethys and the aquitanian of the mediterranean in the slovenian corridor a seaway linking the central paratethys and the mediterranean the presence of rare specimens of discoaster druggii and helicosphaera carteri allows stratigraphic correlation with the transition of nn1 triquetrorhabdulus carinatus zone and nn2 discoaster druggii zone of martini martini e 1971 standard tertiary and quarternary calcareous nannoplankton zonation in farinacci a ed proceedings of the ii planctonic conference roma 1970 ed technoscienza pp 739 785 pentaliths belong to two species braarudosphaera bigelowii and micrantholithus vesper both species display a wide range of morphological variation and most likely represent a group of sibling species the pattern of distribution of both species displays obvious similarities throughout most of the studied interval in the upper part of the studied interval b bigelowii reaches maximum abundance while m vesper disappears since the ability of b bigelowii to thrive in hyposaline water is well known it appears that m vesper tolerates reduced water salinity as well but to a lesser extent than b bigelowii no significant paleoclimatic and paleogeographical changes are known in this particular region during the early miocene however the onset of far reaching extensional tectonic processes took place during this time the enrichment of nannoplankton assemblage with pentaliths may represent a reflection of a short lived episode of hyposaline conditions enhanced influx of freshwater and terrigenous material is indicated by a drop in 13c values a rise in nannoplankton productivity and the presence of sand in some samples from the pentalith enriched strata the most likely causes of this episode are regional tectonic changes associated with the onset of intensive tectonic activity in the western part of the central paratethys

determination of rapid deccan eruptions across the cretaceous tertiary boundary using paleomagnetic secular variation 2 constraints from analysis of eight new sections and synthesis for a 3500 m thick composite section 1 the present paper completes a restudy of the main lava pile in the deccan flood basalt province trap of india chenet et al 2008 reported results from the upper third and this paper reports the lower two thirds of the 3500 m thick composite section the methods employed are the same i e combined use of petrology volcanology chemostratigraphy morphology k ar absolute dating study of sedimentary alteration horizons and as the main correlation tool analysis of detailed paleomagnetic remanence directions the thickness and volume of the flood basalt province studied in this way are therefore tripled a total of 169 sites from eight new sections are reported in this paper together with the results of chenet et al 2008 these data represent in total 70 of the 3500 m combined section of the main deccan traps province this lava pile was erupted in some 30 major eruptive periods or single eruptive events see each with volumes ranging from 1000 to 20 000 km3 and 41 individual lava units with a typical volume of 1300 km3 paleomagnetic analysis shows that some sees with thicknesses attaining 200 m were emplaced over distances in excess of 100 km both likely underestimates due to outcrop conditions and up to 800 km the total time of emission of all combined sees could have been much less than 10 ka with most of the time recorded in a very small number of intervening alteration levels marking periods of volcanic quiescence so called big red boles the number of boles thickness of the pulses and morphology of the traps suggest that eruptive fluxes and volumes were larger in the older formations and slowed down with more and longer quiescence periods in the end on the basis of geochronologic results published by chenet et al 2007 and paleontological results from keller et al 2008 we propose that volcanism occurred in three rather short discrete phases or megapulses an early one at 67 5 1 ma near the c30r c30n transition and the two largest around 65 1 ma one entirely within c29r just before the k t boundary the other shortly afterward spanning the c29r c29n reversal we next estimate sulfur dioxide likely a major agent of environmental stress amounts and fluxes released by sees they would have ranged from 5 to 100 gt and 0 1 to 1 gt a respectively over durations possibly as short as 100 years for each see the chemical input of the chicxulub impact would have been on the same order as that of a very large single pulse the impact therefore appears as important but incremental neither the sole nor main cause of the cretaceous tertiary mass extinctions

anthropogenic stable cesium in water and sediment of a shallow estuary st louis bay mississippi abstract st louis bay slb mississippi is a small shallow estuary with moderate local residential and industrial development dissolved stable cs i e 133 cs was significantly enriched in bay waters up to 1570 nm as compared to river 2 refinery located on the north shore of the bay is the likely source of the cs given that the highest cs concentrations were found in waters and in surface sediments up to 49 g g near the refinery outfall this setting presented a unique opportunity to study remobilization of cs in a shallow estuarine system where sediment resuspension is frequent remobilization up to 3 fold increase of dissolved cs was observed during sediment resuspension events a weak correlation between cs and clay strong correlations among cs silt and particulate organic carbon poc and simple numerical approaches indicate that desorption from resuspended particulate matter is the likely mechanism of cs remobilization cs enriched slb waters can be traced to nearshore mississippi sound waters but not into mississippi bight waters further offshore the findings from this study also suggest that caution needs to be taken when interpreting the radio cesium distribution in shallow estuarine and coastal systems

the middle eocene climatic optimum event in the contessa highway section umbrian apennines italy we report a high resolution paleomagnetic investigation constrained by new qualitative and semiquantitative analyses of planktic and benthic foraminifera nannofossil assemblages integrated with oxygen and carbon isotope measurements for the middle eocene scaglia limestones of the contessa highway section central italy calcareous plankton assemblages enable recognition of several biostratigraphic events from planktic foraminiferal zone p11 to the lower part of zone p15 and from calcareous nannofossil zone np15 to the upper part of zone np17 which results in refi nement of the magnetobiostratigraphy of the contessa highway section correlation of the paleomagnetic polarity pattern with the geomagnetic polarity time scale provides a direct age interpretation for strata around the middle eocene scaglia limestones of the contessa highway section from chrons c21n 47 ma through to subchron c18n 1n 38 5 ma bulk carbon isotope values indicate a distinct carbon isotopic shift at 40 ma that is interpreted to represent the fi rst evidence in the northern hemisphere of the middle eocene climatic optimum which has recently been observed as a stable isotope anomaly in multiple records from the indian atlantic sector of the southern ocean this demonstrates a global response of the carbon cycle to the proposed transient increased pco 2 levels during the late middle eocene and consequent global co 2 driven climate change

extended cretaceous tertiary boundary extinctions and delayed population change in planktonic foraminifera from brazos river texas high resolution planktonic foraminiferal analysis of three brazos river sections indicates a nearly continuous cretaceous tertiary k t boundary sedimentary record second only to the world s most complete record at el kef tunisia species extinctions occur over an extended period of time and with two major extinction episodes the first extinction episode with 46 of the species extinct occurs at and just below 10 15 cm a short hiatus at the base of a sandy shell hash and clay sand unit which was interpreted by bourgeois et al 1988 to represent a tsunami bed generated by the k t boundary bolide impact the top of this tsunami bed is about 17 20 cm below the k t boundary as defined by the first appearance of tertiary planktonic foraminifera the second extinction phase with 45 of the species extinct occurs 25 cm above the k t boundary zone p0 p1a boundary of the remaining seven surviving cretaceous species six gradually disappear during planktonic foraminiferal subzones p1a and basal p1b no species extinctions or major faunal assemblage changes are directly associated with the k t boundary iridium distribution is ambiguous with one peak in the upper part of the tsunami bed and a second peak at the micropaleontologically defined k t boundary relative abundances of dominant species are stable through the late maastrichtian and only minor abundance changes coincide with the first extinction episode or the k t boundary the first major faunal change in the dominant species group coincides with the second extinction episode and leads to decline and eventual extinction of this group in subzone p1a species disappearing at the two extinction episodes 46 and 45 constitute only a small percentage 8 and 5 of the individuals of the total planktonic foraminiferal population this suggests that weakened species with low numbers of individuals and sensitive to relatively minor environmental changes were primarily affected by these extinction episodes magnetostratigraphy indicates that the first extinction phase began about 310 000 years before the k t boundary and the second extinction phase occurred 50 000 years after the k t boundary this stepped pattern of species extinctions suggests a progressively stressed ecosystem in continental shelf settings which may be related to an observed sea level regression and global cooling the hypothesis of a global catastrophic mass extinction at the k t boundary caused by a large extraterrestrial impact is not supported by the brazos river planktonic foraminiferal data

untangling the palaeocene climatic rhythm an astronomically calibrated early palaeocene magnetostratigraphy and biostratigraphy at zumaia basque basin northern spain abstract the magnetostratigraphy of a 54 m long section above the cretaceous tertiary boundary at the sea cliff section of zumaia in the basque basin northern spain has been established the section encompasses the entire danian and the lower part of the selandian stages as indicated by calcareous plankton biostratigraphy the studied interval consists of hemi pelagic limestone marl alternations in the form of couplets and bundles which range from centimetre decimetre to metre scale respectively and a few thin bedded calcareous turbidites the magnetostratigraphy based on samples from about 200 stratigraphic levels allows the identification of six reversal boundaries from chron c29r to c26r at a bed level the spatial or temporal evolution of periodicities from a lithologically coded series is studied with the continuous wavelet transform technique a preliminary age model based on the standard ck95 gpts indicates that the basic lithologic carbonate marl couplet corresponds to the 19 23 kyr precession cycle 21 31 cm cycle in the depth domain and that a bundle cycle usually groups of four to six basic couplets with global periodicity centred at 1 22 m corresponds to the 110 kyr eccentricity cycle we have tuned the bundle cycles to the va03 r7 eccentricity orbital solution astrophys j 592 2003 620 630 following an initial match of a node of the 2 4 ma eccentricity modulatory cycle in the target time series to particularly carbonate rich bundles from the upper part of the zumaia section that displays significant power of a 4 4 m period cycle corresponding to the 404 kyr eccentricity cycle consistency between lithologic patterns and characteristics in the eccentricity target is reasonably met although the 404 kyr eccentricity cycle is not persistent throughout the tuning however appears robust as it brings the age of the k t boundary at 65 8 ma it is argued that a sea level signal tectonically driven is superimposed on the climatic forcing at the milankovitch band masking the full expression of the low frequency astronomical periods we provide a cycle tuned duration for all intervening early palaeocene polarity chrons and estimate relative ages for bioevents the cycle tuned chronology indicates that the ck95 gpts overestimates the duration of chrons c28 and c27 by 20 and 26 respectively our data may prove useful to better constrain early palaeocene biostratigraphy of calcareous plankton and in the redefinition of the boundary between the danian and selandian stages

penetration of lightning mf signals to the upper ionosphere over vlf ground based transmitters 1 the mf data recorded by the low altitude satellite demeter have been used to survey the mf waves around the earth a global map of the mf emissions indicates that there exists a wave activity in the frequency range 2 2 5 mhz above the main powerful vlf ground based transmitters operating in the frequency range 18 50 khz it is shown that this is due to the high frequency part of whistlers induced by the thunderstorm activity they can penetrate trough the ionosphere at the locations of the transmitters because these transmitters induce large ionospheric perturbations this means that an integrated map over several months is able to show these mf emissions above all main vlf transmitters the discrepancy between intensities of the emissions in winter and summer in the northern hemisphere is explained by considering the geographic variations of the plasma frequency below the satellite it is shown that the mf waves spread in longitude in the hemisphere opposite to the vlf transmitters

oxygen and carbon isotope stratigraphy of the palaeogene and cretaceous limestones in the bottaccione gorge and the contessa highway sections umbria italy we have made oxygen and carbon isotope measurements on limestone samples of albian to eocene age recovered from the bottaccione gorge section in the umbrian apennines central italy additional measurements have been made on topmost maastrichtian and palaeocene sediments from the adjacent contessa highway section our data from the bottaccione gorge show 13c maxima at the cenomanian turonian boundary and during the palaeocene as well as a pronounced 13c minimum 7 metres above the clay layer at the k t boundary our data from the contessa highway show a 13c minimum 9 metres above the k t boundary clay these minima are probably diagenetic artifacts in the bottaccione gorge there is evidence for a hiatus in the early middle eocene the palaeocene of the bottaccione gorge appears to have been affected by slumping or faulting in addition to the diagenetic overprinting giving a spurious 13c recovery after the k t boundary the contessa highway section appears to be more complete the coniacian maastrictian is characterized by relatively stable 13c values our data indicate an increase in 18o and therefore possible cooling across the cretaceous tertiary boundary in both the bottaccione and contessa highway sections

calcareous nannofossil extinction and survivorship across the cretaceous paleogene boundary at walvis ridge odp hole 1262c south atlantic ocean abstract site 1262 in the south atlantic ocean has provided a stratigraphically continuous deep cretaceous paleogene boundary sequence high resolution calcareous nannofossil quantitative analyses were carried out across the k p boundary and provided a remarkable record of the abrupt and catastrophic extinction the calcareous nannofossil assemblages are abundant and well preserved allowing to obtain a precise bioevent sequence and to document in detail the survivors and victims and the subsequent recovery across the k p boundary late maastrichtian diversity and absolute abundance is high and no decrease towards the boundary has been observed the relative abundance of cretaceous species does not suffer important changes during the latest maastrichtian however the increase in abundance of cool water taxa paralleled with a decrease of warm water taxa in the uppermost 2 cm of the maastrichtian revealed a pulse of surface water cooling the k p boundary is marked by an important decrease in calcareous nannofossil absolute abundance the increase of cretaceous persistent species such as cyclagelosphaera reinhardtii together with the dinoflagellate cysts of thoracosphaera operculata and the appearance of the new paleocene taxa cyclagelosphaera alta and biantholithus sparsus these events are followed by the successive relative abundance increases of other cretaceous survivors as zeugrhabdotus sigmoides markalius inversus and biscutum recognized as r selected taxa adapted to eutrophic and cold water environments in the early danian several first occurrences of small new paleocene species have been observed calcareous nannoplankton evolutionary attempts to colonize vacant niches left by the extinct cretaceous species only some forms succeed and become ancestors to the cenozoic assemblages the other disappear in few kiloyear the presence of a reworking mixing interval above the k p boundary hampered to unequivocally interpret if the few cretaceous vanishing taxa may have survived for a very short time after the k p extinction

sulfur and chlorine in late cretaceous deccan magmas and eruptive gas release large volume p hoehoe lava flows erupted 67 to 65 million years ago forming the deccan traps india the impact of these flood basalt eruptions on the global atmosphere and the coeval end cretaceous mass extinction has been uncertain to assess the potential gas release from this volcanism we measured sulfur and chlorine concentrations in rare glass inclusions inside crystals and on glassy selvages preserved within lavas concentrations range from 1400 parts per million of s and 900 parts per million of cl in inclusions down to a few hundred parts per million in the lava these data indicate that eruptions of deccan lavas could have released at most 0 103 weight of s yielding up to 5 4 teragrams of so2 per cubic kilometer of lava a more conservative estimate is 0 07 weight of s and 0 04 weight of cl yielding 3 5 teragrams of so2 and 1 teragram of hcl for every cubic kilometer of lava erupted the flows were very large in volume and these results imply that huge amounts of s and cl gases were released the environmental impact from even individual eruptions during past flood basalt activity was probably severe

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

greenhouse crises of the past 300 million years proxies of past co 2 and climate over the past 300 m y now reveal multiple global climate change events in unprecedented detail evidence for past co 2 spikes comes from expanded and refined data on stomatal index of fossil ginkgo and related leaves new evidence for synchronous climatic change comes from paleosols in montana utah and neighboring states each co 2 spike was coeval with unusually clayey red and decalcified paleosols which can be traced throughout the colorado plateau spikes in atmospheric co 2 also were coeval with increases in paleosol alkali depletion as an indication of high temperature and spikes in paleosol base depletion and depth to calcic horizons as indications of high precipitation in the colorado plateau times of warmer climate were also more humid perhaps due to greater moisture potential of warmer air seasonality of climate did not increase during warm wet spikes the mesozoic greenhouse was not persistently hot with cool spells but warm with hot flashes these data furnish power laws predicting the sensitivity and magnitude of change in mean annual temperature mat and mean annual precipitation map due to rising co 2 in a mid latitude mid continental region the magnitude of the coming anthropogenic greenhouse pales in comparison with past greenhouse spikes at times of global mass extinctions

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

carbon dioxide emissions from deccan volcanism and a k t boundary greenhouse effect a greenhouse warming caused by increased emissions of carbon dioxide from the deccan traps volcanism has been suggested as the cause of the terminal cretaceous extinctions on land and in the sea we estimate total eruptive and noneruptive co2 output by the deccan eruptions from 6 to 20 1016 moles over a period of several hundred thousand years based on best estimates of the co2 weight fraction of the original basalts and basaltic melts the fraction of co2 degassed and the volume of the deccan traps eruptions results of a model designed to estimate the effects of increased co2 on climate and ocean chemistry suggest that increases in atmospheric pco2 due to deccan traps co2 emissions would have been less than 75 ppm leading to a predicted global warming of less than 1 c over several hundred thousand years we conclude that the direct climate effects of co2 emissions from the deccan eruptions would have been too weak to be an important factor in the end cretaceous mass extinctions

transient ocean warming and shifts in carbon reservoirs during the early danian the palaeocene eocene thermal maximum petm at 55 ma marks the palaeocene eocene p e boundary and represents a discrete period of abrupt transient global warming there are few vegetation records from within the petm and such an absence of data prevents modelling of the vegetation response to climate warming outcrops exposing the sentinel butte member upper fort union formation and the golden valley formation bear den and lower camels butte members within the williston basin of western north dakota usa are known to span the p e boundary pollen and spore floras at the farmers butte locality stark county north dakota 46 92 n 102 11 w record changes in abundance of some reed fern and understorey plants across the sentinel butte bear den contact but no other composition changes occur until the arrival of eocene immigrants platycarya spp walnut pecan family and intratriporopollenites instructus linden sterculia cotton tree families at the top of the bear den member c 11 m above the change in co occurrence and relative abundance patterns of range through taxa the exact stratigraphic level at which these eocene marker taxa first occur is unclear owing to the heavily weathered nature of bear den strata below the alamo bluff lignite this pattern of stratigraphic change may be correlative to the well documented floral gap of petm records in wyoming though bulk 13corg ratios decrease by 2 4 across the alamo bluff lignite degradation of organic carbon within the upper bear den member partially masks full expression of the carbon isotope excursion associated with the petm hence strata around the alamo bluff lignite may represent a new terrestrial record of the petm in agreement with terrestrial petm records from other u s western interior localities palynological data indicate no floral extinction and little composition change across the palaeocene eocene boundary

co2 forced climate thresholds during the phanerozoic abstract the correspondence between atmospheric co2 concentrations and globally averaged surface temperatures in the recent past suggests that this coupling may be of great antiquity here i compare 490 published proxy records of co2 spanning the ordovician to neogene with records of global cool events to evaluate the strength of co2 temperature coupling over the phanerozoic last 542 my for periods with sufficient co2 coverage all cool events are associated with co2 levels below 1000 ppm a co2 threshold of below 500 ppm is suggested for the initiation of widespread continental glaciations although this threshold was likely higher during the paleozoic due to a lower solar luminosity at that time also based on data from the jurassic and cretaceous a co2 threshold of below 1000 ppm is proposed for the initiation of cool non glacial conditions a pervasive tight correlation between co2 and temperature is found both at coarse 10 my timescales and fine resolutions up to the temporal limits of the data set million year timescales indicating that co2 operating in combination with many other factors such as solar luminosity and paleogeography has imparted strong control over global temperatures for much of the phanerozoic

main deccan volcanism phase ends near the k t boundary evidence from the krishna godavari basin se india abstract recent studies indicate that the bulk 80 of the deccan trap eruptions occurred over less than 0 8 m y in magnetic polarity c29r spanning the cretaceous tertiary k t boundary determining where within this major eruptive phase the k t mass extinction occurred has remained problematic for this reason models estimating the biotic and environmental consequences have generally underestimated the rate and quantity of deccan gas emissions by orders of magnitude leading to conclusions that volcanism could not have been one of the major causes for the k t mass extinction in this study we report that the most massive deccan trap eruption occurred near the k t mass extinction these results are based on sedimentologic microfacies and biostratigraphic data of 4 9 m thick intertrappean sediments in four quarry outcrops in the rajahmundry area of the krishna godavari basin of southeastern india in this area two deccan basalt flows known as the rajahmundry traps mark the longest lava flows extending 1500 km across the indian continent and into the bay of bengal the sediments directly overlying the lower rajahmundry trap contain early danian planktic foraminiferal assemblages of zone p1a which mark the evolution in the aftermath of the k t mass extinction the upper rajahmundry trap was deposited in magnetic polarity c29n preceding full biotic recovery these results suggest that volcanism may have played critical roles in both the k t mass extinction and the delayed biotic recovery

南西太平洋における20世紀の海面温度変動性についての再構築 ニューカレドニアの複数の珊瑚礁sr ca記録を使用した複製研究

new chronostratigraphy of the cretaceous paleogene boundary interval at bidart france abstract the cretaceous paleogene boundary section at bidart french basque coast was prevented for a long time to be considered as a reference section for the k t boundary due to a suspected hiatus comprising most of chron c29r in our new magneto and biostratigraphic study of this section we discovered that the underlying primary magnetic polarity is not revealed in the vector directions but in a small but consistent intensity excursion during laboratory demagnetization trends magnetite and maghemite are the main carriers of remanence with contribution of hematite to the magnetic mineralogy of the red brown lowermost danian and maastrichtian marly limestones magnetite is the main magnetic mineral in the white to pink danian limestones the nrm of marls and marly limestones is characterized by 1 a present day field overprint 2 a medium temperature 300 400 c reversed component interpreted as a relic of the characteristic remanent magnetization chrm carried by magnetite grains which are not completely oxidized into maghemite and 3 a high temperature up to 590 c normal component due to late diagenesis hematite growth the nrm of danian limestones is characterized by 1 a present day field overprint and 2 a chrm component of normal or reversed polarity the chrm directions allow a new correlation of the magnetic polarity sequence with the geomagnetic polarity time scale gpts chron c29r corresponds to the maastrichtian unit and extends up to 3 5 m above the k t boundary and chron c29n occurs at the top of the section there is no evidence for a hiatus at or below the k t boundary and the section does not extend up to chron c28r as previously suggested these new chronostratigraphic assignments are in good agreement with the previous biostratigraphic data and from the new biostratigraphic analyses based on calcareous nannofossils presented in this paper our study demonstrates that the section of bidart can be considered as a key section to study the k t boundary event s

high cesium concentrations in groundwater in the upper 1 2 km of fractured crystalline rock influence of groundwater origin and secondary minerals abstract dissolved and solid phase cesium cs was studied in the upper 1 2 km of a coastal granitoid fracture network on the baltic shield aspo hard rock laboratory and laxemar area se sweden there unusually high cs concentrations up to 5 6 g l 1 occur in the low temperature 1 median laxemar 3 7 g l 1 and groundwater with marine origin aspo hrl 4 2 g l 1 overall lower but variable cs concentrations were found in other types of groundwater the similar concentrations of cs in the saline groundwater which had a residence time in the order of millions of years and in the marine groundwater which had residence times in the order of years shows that duration of water rock interactions is not the single and primary control of dissolved cs in these systems the high cs concentrations in the saline groundwater is ascribed to long term weathering of minerals primarily cs enriched fracture coatings dominated by illite and mixed layer clays and possibly wall rock micaceous minerals the high cs concentrations in the groundwater of marine origin are in contrast explained by relatively fast cation exchange reactions as indicated by the field data and predicted by 1d solute transport modeling alkali cations with low energy hydration carried by intruding marine water are capable of nh 4 in particular and k to some extent replacing cs on frayed edge fes sites on illite in the fracture coatings the result is a rapid and persistent at least in the order of decades buildup of dissolved cs concentrations in fractures where marine water flows downward the identification of high cs concentrations in young groundwater of marine origin and the predicted capacity of nh 4 to displace cs from fracture solids are of particular relevance in the disposal of radioactive nuclear waste deep underground in crystalline rock

40k 40ar dating of the main deccan large igneous province further evidence of ktb age and short duration most mass extinctions coincide in time with outpourings of continental flood basalts cfb some 20 years ago it was shown courtillot v besse j vandamme d montigny r jaeger j j cappetta h 1986 deccan flood basalts at the cretaceous tertiary boundary earth planet sci lett 80 361 374 courtillot v feraud g maluski h vandamme d moreau m g besse j 1988 deccan flood basalts and the cretaceous tertiary boundary nature 333 843 846 duncan r a pyle d g 1988 rapid eruption of the deccan flood basalts at the cretaceous tertiary boundary nature 333 841 843 that the age of the deccan traps was close to the cretaceous tertiary kt boundary and its duration under 1 myr we have undertaken a new geochronological study using the unconventional 40k 40ar cassignol gillot technique which is particularly well suited to the potassium poor deccan lavas the mean of 4 determinations from the topmost ambenali and mahabaleshwar formations is 64 5 0 6 ma they straddle the c29r c29n reversal boundary for which they provide a new constraint the mean age of 3 determinations from the oldest jawhar formation is 64 8 0 6 ma the difference in age between top and bottom of a 3500 m composite section probably comprising 80 of the total deccan volume is statistically insignificant with the overall mean age being 64 7 0 6 ma n 7 our results are consistent with the most recent 40ar 39ar determinations knight k b renne p r halkett a white n 2003 40ar 39ar dating of the rajahmundry traps eastern india and their relationship to the deccan traps earth planet sci lett 208 85 99 knight k b renne p r baker j waight t white n 2005 reply to 40ar 39ar dating of the rajahmundry traps eastern india and their relationship to the deccan traps discussion by a k baksi earth planet sci lett 239 374 382 confirming that there should be no systematic difference between the two methods when they are used in an optimal way an earlier smaller but significant pulse of volcanism between 68 and 67 ma extending over at least 500 km in latitude in the northern part of the deccan cfb has also been identified after 2 to 3 ma of quiescence the second major phase of volcanism occurred near 65 ma expanding over most of the area covered by the first pulse and another 500 km to the south consistent with drift of india by 300 to 450 km at not vert similar 150 mm yr during the quiescence period new paleontological data from the remote rajahmundry section keller g adatte t gardin s bartolini a bajpai s humler e in prep the cretaceous tertiary boundary in deccan traps of the krishna godavari basin of southeastern india epsl to be submitted suggest that this second pulse can itself be divided into two major pulses one starting in c29r and ending at the kt boundary the second starting in the upper part of c29r and ending within c29n

perturbation at the sea floor during the paleocene eocene thermal maximum evidence from benthic foraminifera at contessa road italy abstract detailed analyses of the benthic foraminiferal assemblages extracted with the cold acetolyse method together with high resolution geochemical and mineralogical investigations across the paleocene eocene p e boundary of the classical succession at contessa road western tethys allowed to recognize and document the paleocene eocene thermal maximum petm interval the position of the benthic extinction event bee and the early recovery of benthic faunas in the aftermath of benthic foraminiferal extinction the stratigraphical interval spanning the p e boundary consists of dominantly pelagic limestones and two prominent marly beds benthic foraminifera indicate that these sediments were deposited at lower bathyal depth not deeper than 1000 1500 m the carbon isotope excursion cie interval is characterized by high barite abundance with a peak at the base of the same stratigraphic interval indicating a complete although condensed record of the early cie a succession of events and changes in the taxonomic structure of benthic foraminifera has been recognized that may be of use for supra regional stratigraphic correlation across the p e boundary interval the composition of the benthic foraminiferal assemblages dominated by infaunal taxa indicates mesotrophic and changing conditions on the sea floor during the last 45 kyr of the paleocene the bee occurs at the base of the cie within the lower marly bed and it is recorded by the extinction of several deep water cosmopolitan taxa then the lysocline ccd rose and severe carbonate dissolution occurred preservation deteriorated the faunal density and simple diversity dropped to minimum values and a peak of glomospira spp has been observed stress tolerant and opportunistic groups represented mainly by bi and triserial taxa dominate the low diversity post extinction assemblages indicating a benthic foraminiferal recovery under environmental unstable conditions probably within a context of sustained food transfer to the bottom a three phase pattern of faunal recovery is recognizable at first the lysocline ccd started to descend and then recovered small sized bulimina oridorsalis umbonatus and tappanina selmensis rapidly repopulated the severely stressed environment later on siphogenerinoides brevispinosa massively returns dominating the assemblage together with other buliminids nuttallides truempyi and anomalinoides sp 1 finally a marked drop in abundance of s brevispinosa is followed by a bloom of the opportunistic and recolonizer agglutinated pseudobolivina that for the first time is recorded within the main cie a second interval of dissolution but less severe than the previous one has been recognized within the upper marly bed uppermost part of the main cie interval and it is interpreted as a renewed less pronounced shoaling of the lysocline ccd that interrupted the recovery of benthic faunas this further rise likely represents a response to persistent instability of ocean geochemistry in this sector of the tethys before the end of the cie in the cie recovery and post cie intervals the composition of the benthic foraminiferal assemblages suggests mesotrophic and unstable conditions at the sea floor according to the geochemical proxy for redox conditions the deposition of the petm sediments at contessa road occurred in well oxygenated waters leading out a widespread oxygen depletion as major cause of the bee changing oceanic productivity carbonate corrosivity and global warming appear to have played a much more important role in the major benthic foraminiferal extinction at the p e boundary

hf signatures of powerful lightning recorded on demeter 1 emissions in the hf range 1 7 3 mhz are observed at the times of powerful lightning on the low altitude satellite demeter at 700 km wave activity observed on the e field spectrograms recorded on demeter during nighttime is mainly dominated by upgoing 0 whistlers and higher order dispersed whistlers over a period of 30 months 130 events with hf emissions at frequency 2 mhz have been observed at the time of intense 0 whistlers on vlf spectrograms a global map of the distribution of events indicates that they do not occur above regions of most thunderstorm activity such as the upper part of south america or the middle of africa this lack of occurrence above these two near equatorial regions is consistent with the high value of the critical frequency of the f layer which prevents the transionospheric propagation of the hf component of the lightning pulses up to 700 km the time location intensity and polarity of the lightning discharges related to a subset of these hf events are determined above the north american region with the national lightning detection network as most of the events are recorded in survey mode when full resolution of the data is not available the neural network on board demeter is used to determine the times of the 0 whistlers recorded by the satellite with a time accuracy of 0 1 s the impulsive hf events correspond to intense lightning discharges occurring in regions immediately below the satellite it is assumed that the propagation of these hf pulses up to the altitude of the satellite is favored by local ionospheric heating due to high thunderstorm activities

reversed deep sea carbonate ion basin gradient during paleocene eocene thermal maximum 1 the paleocene eocene thermal maximum petm 55 ma ago was marked by widespread caco3 dissolution in deep sea sediments a process that has been attributed to massive release of carbon into the ocean atmosphere system the pattern of carbonate dissolution is key to reconstructing changes in deep sea carbonate chemistry and ultimately the rate magnitude and location of carbon input here we show that during the petm the deep sea undersaturation was not homogeneous among the different ocean basins application of a sediment model to a suite of data records from different sites and ocean basins shows that a globally uniform decrease in deep sea carbonate ion concentration co32 is inconsistent with the data rather we demonstrate that deep sea co32 increased from the atlantic through the southern ocean into the pacific our results show that the petm deep sea co32 basin gradient during dissolution was reversed relative to the modern

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

measuring the specific caesium sorption capacity of soils sediments and clay minerals abstract two methods to quantify the specific cs sorption capacity of soils and sediments which is generally believed to be associated with the frayed edge sites fes of illitic clay minerals are described in detail and are critically reviewed the first method is a direct measurement of the fes capacity while the second quantifies the combined parameter k d cs k k c k cs fes i e the product of the fes capacity and the affinity of these sites for cs both methods use the bulky agtu complex to mask non specific sorption sites for cs and are applied to a number of different soils and pure minerals measurement of the fes capacity of pure illite is straightforward it is shown that the measured capacity is independent of the saturating ion but does depend on particle size this method could not be successfully applied to a peat bog soil with 90 organic matter because the necessary correction for non specific cs sorption by the large pool of organic exchange sites overpasses the capacity of the small fes fraction measurement of the combined parameter k d cs k is shown to be more appropriate in such cases application of the fes capacity method to the hydrous aluminosilicate mineral allophane an important soil constituent of andisols shows that the agtu complex is unable to block all non specific sorption sites for cs on this mineral the k d cs k measurements show evidence of a very small number of specific cs sorption sites on allophane much smaller than inferred from the fes capacity measurement the fes capacity of the clay mineral vermiculite is difficult to quantify because the high cs concentrations that are needed to measure the fes capacity probably cause a collapse of the vermiculite interlayers thereby creating more high affinity sites for cs the k d cs k method in which only trace concentrations of cs are used is shown to be more appropriate for soils containing substantial amounts of vermiculite it is concluded that both the direct fes capacity measurement and the measurement of the combined parameter k d cs k can be very useful methods to isolate and characterise cs selective sorption sites in soils and sediments but that results should be interpreted with great care

the paleocene eocene thermal maximum as recorded by tethyan planktonic foraminifera in the forada section northern italy abstract the forada section in the venetian pre alps of northern italy represents an expanded record of the paleocene eocene thermal maximum petm at a depositional paleodepth of about 1 km 0 5 km high resolution planktonic foraminiferal analysis of this section in a time interval of approximately 1 3 myr across the paleocene eocene boundary reveals striking faunal changes that allow the identification of eight phases a h the late paleocene was represented by stable warm and oligotrophic surface water conditions phase a unstable environmental conditions start well before the onset of petm ca 150 kyr phase b and involved a change towards eutrophy as marked by the increase of subbotina and the concomitant decrease of morozovella this step is also characterized by enhanced fragmentation and dissolution the interval corresponding to the main body of the carbon isotope excursion cie is characterized by a marked increase of acarinina though with some differences in the species composition and relative abundance both in high and low latitudes particularly in the tethyan area forada is no exception to this pattern however at forada two prominent peaks in abundance of acarininids are recorded ca 30 kyr prior to the onset of the cie thus suggesting an increase in temperature heralding the onset of the petm phase c interestingly the lower peak in abundance of acarinina just precedes the 1 carbon isotope negative shift occurring below the onset of the main cie the basalmost eocene corresponding to the lower part of cie curve is represented by intense planktonic foraminiferal dissolution implying an extraordinary rise of the ccd this interval has an estimated duration of about 16 kyr phase d the dominance of acarininids in the lower part of the cie phase e f ca 14 and 22 5 kyr is interpreted as a consequence of the extreme warmth coupled with eutrophic conditions characterizing the forada depositional environment at that time these acarininids include at forada also the temporally constrained acarinina sibaiyaensis and a africana the morphological similarity between these peculiar species with the radially elongated chambered forms characterizing the cretaceous anoxic events suggests the hypothesis that depletion of oxygen in the upper water column might have been one of the factors causing their conspicuous occurrence at the petm the recovery in abundance of the specialized morozovellids and of other planktonic foraminiferal groups e g biserials globanomalinids igorinids planorotalids and pseudohastigerinids occurring in the middle part of the cie ca 30 kyr after the onset of the petm indicates an initial environmental recovery phase g a new stable state is definitely reached in the upper part of the forada section where the relative proportions of the main component of planktonic foraminiferal assemblages move towards values similar to those of the late paleocene conditions phase h however the perturbation during the petm produced significant changes in the ocean geochemistry that endured after the petm event as testified by the prominent high carbonate dissolution characterizing the marly levels and the large variability in relative abundance among different components of the planktonic foraminiferal assemblages these striking oscillations were not present in the latest paleocene

the dan c2 hyperthermal event at gubbio italy global implications environmental effects and cause s abstract the dan c2 event is an early danian transient 100 kyr hyperthermal episode centered at 65 2 ma which records shifts in carbon reservoirs and ocean warming in the northwestern and southeastern sectors of the atlantic ocean here we present and discuss high resolution biochronostratigraphic and magnetic susceptibility data and geochemical records from the western tethyan contessa highway section gubbio italy which provide the first direct evidence of the dan c2 event beyond the atlantic ocean and point to the supra regional possibly global significance thereof at contessa highway the dan c2 event exhibits stressed ecological responses among calcareous nannoplankton and foraminifera which highlight marked environmental perturbation affecting the geobiosphere and resulting in enhanced eutrophication of the sea surface waters and carbonate dissolution as well as lowered oxygen content along the water column and at the sea bottom as for other early paleogene hyperthermal events the cause of the dan c2 event might likely to be found in changes potentially astronomically paced in the distribution of carbon within surface biosphere reservoirs however the role played by the concurrent third and last phase of deccan volcanism with its huge release of greenhouse gases into the atmosphere would be also taken into account in addition here we provide first evidence of a further short lived 38 kyr hyperthermal event not known up to now and that we term the lower c29n event

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

latest danian carbon isotope anomaly and associated environmental change in the southern tethys nile basin egypt abstract during the palaeocene and eocene epochs 65 5 33 9 ma the earth experienced the warmest conditions of the cenozoic this palaeogene greenhouse episode is characterized by several short lived negative carbon isotope 13 c excursions which are usually interpreted as transient warming events hyperthermals9 as indicated by rising temperatures of surface and bottom waters and accompanied carbonate dissolution in deep sea settings among these events the palaeocene eocene thermal maximum petm c 55 5 ma is globally the best documented and most prominent further negative 13 c anomalies have recently been identified in the eocene but the early to middle palaeocene has mostly been neglected here benthic foraminiferal 13 c records are presented from four upper danian lower selandian sections in the nile basin eastern egypt all records show a negative 13 c shift with an amplitude of up to 2 at the base of planktonic foraminiferal subzone p3b c 61 ma the supra regional nature of this event is emphasized by correlation with a well dated similar 13 c record from zumaia spain lithological changes the 13 c signature and biotic responses strongly resemble those of the petm in egypt which leads to the hypothesis that this latest danian event9 lde may represent another early palaeocene hyperthermal

an expanded cretaceous tertiary transition in a pelagic setting of the southern alps central western tethys abstract an integrated micropalaeontological planktonic foraminifera and calcareous nannofossils mineralogical and stable isotope investigation was carried out across the cretaceous tertiary k t boundary in a previously undescribed hemipelagic section forada section cropping out in the piave river valley southern alps belluno province ne italy our results suggest that an apparently complete k t transition with an expanded basal danian is preserved in the forada section the k t boundary is marked by a ca 1 5 cm thick clay interval intercalated in the pelagic carbonates of the scaglia rossa formation the boundary clay characterised by an iridium anomaly is constituted by a basal 1 2 mm thick green layer and an overlying red layer below the boundary clay the calcareous nannofossil micula murus zone and the planktonic foraminiferal plummerita hankteninoides zone that characterise the terminal maastrichtian in complete sections have been identified virtually all the calcareous plankton biohorizons normally utilised in the early danian have been recognised interestingly the ranking of the various biohorizons is the same observed elsewhere if considering the single plankton groups separately while several inconsistencies emerge if considering the relative succession of the two calcareous plankton groups simultaneously we caution to infer hiatuses on a section based only on the spacing of the biohorizons of a single group because of the risk of diachroneities in the stressed early danian environment by comparing the distance of the key biohorizons i e the first occurrence fo of cruciplacolithus primus and the last occurrence lo of parvularugoglobigerina eugubina from the boundary clay at forada and in other complete classical sections we have inferred that the early danian is expanded in the forada section the section seems ideally suited for studying the recovery pattern of the pelagic ecosystem and calcareous plankton communities in the aftermath of the k t catastrophe in a pelagic setting of the western central tethys the adaptive radiation of planktonic foraminifera was very rapid in contrast with the delayed diversification of coccolithophores the latter show a ca 21 cm thick dead zone that is followed by a long lasting survival interval ca 180 cm thick that might represent some 200 kyr dominated by persistent cretaceous coccolithophores and calcareous dinoflagellate thoracosphaera spp the temporal pattern in recovery of the coccolithophore and planktonic foraminiferal communities is decoupled as well pointing to their varying sensitivities to the k t perturbation it appears that the ecospace occupied by coccolithophores in the terminal maastrichtian was occupied in the initial danian by the calcareous dinoflagellates thoracosphaera spp that remained a significant component of the assemblage up to the base of the prinsius dimorphosus zone of romein romein a j t 1979 lineages in early paleogene calcareous nannoplankton utrecht micropaleontological bulletins 22 231 pp probably in the early chron c29n on the contrary planktonic foraminifera seem to reach stable conditions earlier in the late cruciplacolithus primus zone the early danian interval considered is also characterised by low sr ca ratio of the biogenic carbonates that would suggest dramatically low coccolithophore productivity conditions in agreement with previous flux studies we speculate that the altered ecological structure of phytoplankton community and the low productivity of coccolithophores severely affected the efficiency of the transfer of organic carbon from the photic zone to the deep ocean thus supporting the early danian living ocean model of d hondt et al d hondt s donaghay p zachos j c luttenberg d lindinger m 1998 organic carbon fluxes and ecological recovery from the cretaceous tertiary mass extinction science 282 276 279

pelagic evolution and environmental recovery after the cretaceous paleogene mass extinction the evolutionary recovery of planktic foraminifera from the cretaceous paleogene mass extinction was closely linked to recovery of the marine carbon system both the evolutionary recovery and the biogeochemical recovery occurred in two stages the second stage of evolutionary radiation peaked nearly four million years after the extinction immediately after the abrupt final recovery of the organic flux to deep waters the timing of these events suggests that the final postextinction recovery of planktic foraminiferal diversity was directly contingent on the final recovery of the marine carbon cycle this second radiation was defined by the diversification of tropical photosymbiotic forms that dominated low and mid latitude assemblages long into the eocene we hypothesize that this diversification was a result of the reappearance of oligotrophic oceans as the organic flux from the surface ocean to deep water fully recovered from the mass extinction

paleogene magnetic stratigraphy in umbrian pelagic carbonate rocks the contessa sections gubbio the umbrian sequence of pelagic carbonate rocks provides an opportunity for precise correlation between paleogene biostratigraphy and geomagnetic polarity history the red to pink paleocene to middle eocene scaglia rossa limestone the varicolored upper eocene scaglia variegata limestone and the gray green oligocene scaglia cinerea marlstone form a 250 m thick continuous exposure in the contessa valley near gubbio italy magnetostratigraphic lithostratigraphic and biostratigraphic investigations in three sections covering the entire paleogene have confirmed and dated the geomagnetic reversal sequence for most of this period the ferromagnetic mineral in the scaglia cinerea is magnetite and af demagnetization to peak fields of 20 mt is sufficient to define the characteristic remanent magnetization the scaglia variegata and pink scaglia rossa samples contain an additional hematite component which is very pronounced in dark red paleocene scaglia rossa samples changes of magnetic mineralogy take place in these limestones during heating especially above 500 c however thermal demagnetization is effective in isolating the characteristic remanence vectors which form almost antipodal clusters of directions representing normal and reversed polarities the directions are rotated counterclockwise partly due to post oligocene tectonism paleontological zonations of planktic foraminifera and calcareous nannofossils were hampered by poor preservation but the major epoch and stage 29 as in the gubbio bottaccione section paleocene eocene just above anomaly 25 eocene oligocene between anomalies 13 and 15 oligocene miocene just below anomaly 6c these correlations require slight modifications to previous conclusions on paleogene sea floor spreading rates

meco and alpine orogenesis constraints for facies evolution of the bartonian nummulitic and solenomeris limestone in the argentina valley ligurian alps

a high resolution benthic stable isotope record for the south atlantic implications for orbital scale changes in late paleocene early eocene climate and carbon cycling abstract the late paleocene and early eocene were characterized by warm greenhouse climates punctuated by a series of rapid warming and ocean acidification events known as hyperthermals thought to have been paced or triggered by orbital cycles while these hyperthermals such as the paleocene eocene thermal maximum petm have been studied in great detail the background low amplitude cycles seen in carbon and oxygen isotope records throughout the paleocene eocene have hitherto not been resolved here we present a 7 7 million year myr long high resolution orbitally tuned benthic foraminiferal stable isotope record spanning the late paleocene and early eocene interval 52 5 60 5 ma from ocean drilling program odp site 1262 south atlantic this high resolution 2 4 kyr record allows the changing character and phasing of orbitally modulated cycles to be studied in unprecedented detail as it reflects the long term trend in carbon cycle and climate over this interval the main pacemaker in the benthic oxygen isotope 18 o and carbon isotope 13 c records from odp site 1262 are the long 405 kyr and short 100 kyr eccentricity cycles and precession 21 kyr obliquity 41 kyr is almost absent throughout the section except for a few brief intervals where it has a relatively weak influence during the course of the early paleogene record and particularly in the latest paleocene eccentricity paced negative carbon isotope excursions 13 c cies and coeval negative oxygen isotope 18 o excursions correspond to low carbonate caco 3 and coarse fraction cf values due to increased carbonate dissolution suggesting shoaling of the lysocline and accompanied changes in the global exogenic carbon cycle these negative cies and 18 o events coincide with maxima in eccentricity with changes in 18 o leading changes in 13 c by 6 5 kyr in the 405 kyr band and by 3 1 kyr in the higher frequency 100 kyr band on average however these phase lags are not constant with the lag in the 405 kyr band extending from 4 5 kyr to 21 2 kyr from the late paleocene to the early eocene suggesting a progressively weaker coupling of climate and the carbon cycle with time the higher amplitude 405 kyr cycles in the latest paleocene are associated with changes in bottom water temperature of 2 4 c while the most prominent 100 kyr paced cycles can be accompanied by changes of up to 1 5 c comparison of the 1262 record with a lower resolution but orbitally tuned benthic record for site 1209 in the pacific allows for verification of key features of the benthic isotope records which are global in scale including a key warming step at 57 7 ma

some patterns of planktic foraminiferal assemblage turnover at the cretaceous tertiary boundary abstract three uppermost cretaceous through basal paleocene stratigraphic sequences are examined for planktic foraminiferal assemblage stability and temporal succession patterns these sequences are at mid latitude south atlantic dsdp site 528 then equatorial pacific dsdp site 577 and the tethyan shelf ben gurion section of the negev israel in order to better estimate biogeographic patterns and habitat preferences the results of these analyses are compared to previous cretaceous biogeographic studies and to previous analyses of cretaceous tertiary k t boundary shelf and epicontinental sections results indicate that immediately following the k t boundary the examined epicontinental and open ocean sites were exploited primarily by previously epicontinental planktic foraminiferal assemblages this pattern of k t boundary assemblage dominance suggests the geologically instantaneous break down of late cretaceous epicontinental and open ocean biogeographic provincialization this shift in open ocean foraminiferal assemblages is not consistent with models of non selective k t boundary extinctions but is consistent with models of extinction resistence and offshore expansion of near shore taxa the re establishment of stable biogeographic differences between open ocean and epicontinental planktic foraminiferal assemblages occurs by the basal parvularugoglobigerina eugubina zone at open ocean sites 528 and 577 and the outer shelf ben gurion section po and p eugubina zone faunal records are marked by a pronounced alternation between paleocene biserial and non biserial dominated assemblages this alternation appears strongly damped at shelf and epicontinental sections previously examined the first appearance and peak magnitude of abundant earliest paleocene trochospiral forms parvularugoglobigerina eoglobigerina morozovella globoconusa also vary from site to site and may depend closely on levels of primary carbonate productivity

cretaceous tertiary boundary sections on the coast of the black sea near bjala bulgaria abstract cretaceous tertiary boundary sections in bulgaria on the coast of the black sea near bjala 35 km south of varna have been identified by biostratigraphic mineralogical geochemical and magnetostratigraphic methods the undisturbed hemipilagic sediments of profile 2b bjala show a mass extinction of cretaceous nannoplankton species as well as a bloom of survivors at the k t boundary and the first occurrence of new nannoplankton species after the k t event a comparison of biostratigraphic and magnetostratigraphic results provides a time scale for the evolution of these new nannoplankton species

synchroneity of the k t oceanic mass extinction and meteorite impact blake nose western north atlantic a 10 cm thick layer of green spherules occurs precisely at the biostratigraphic boundary between the cretaceous and paleogene k t boundary at ocean drilling program site 1049 lat 30 08 n long 76 06 w the spherulitic layer contains abundant rock fragments chalk limestone dolomite chert mica books and schist as well as shocked quartz abundant large cretaceous planktic foraminifera and rounded clasts of clay as long as 4 mm interpreted as altered tektite glass probably derived from the chicxulub impact structure most of the cretaceous foraminifera present above the spherule layer are not survivors since small specimens are conspicuously rare compared to large individuals instead the cretaceous taxa in paleocene sediments are thought to be reworked the first paleocene planktic foraminifera and calcareous nannofossil species are recorded immediately above the spherule bed the upper part of which contains an iridium anomaly hence deposition of the impact ejecta exactly coincided with the biostratigraphic k t boundary and demonstrates that the impact event was synchronous with the evolutionary turnover in the oceans these results are consistent with a reanalysis of the biostratigraphy of the k t boundary stratotype which argues that shallow marine k t boundary sections are not biostratigraphically more complete than deep sea k t boundary sites

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