late glacial early holocene environmental changes in charzykowskie lake northern poland based on oxygen and carbon isotopes and cladocera data abstract based on isotopic and cladoceran investigations of a 6 m long sediment core a reconstruction of paleoenvironmental dynamics in charzykowskie lake northern poland is proposed the sediments consist of sandy silts at the bottom followed in upward succession by gyttja characterized by increasing caco 3 content the measured 18 o values oscillate from 9 3 to 5 and 13 c from 5 7 to 0 4 we identify 24 taxa of subfossil cladocera and six phases caz of faunal development isotopic and cladoceran data together with detrended correspondence analyses dca allow reconstruction of the environmental conditions particularly changes in water level temperature and trophic status during the late glacial and early holocene the lowest water temperature connected with the inflow of cold melt water occurred in the late glacial and preboreal period since the boreal period gradual warming is observed and expressed through a positive trend in both 18 o and 13 c values and changes in cladocera species assemblages the lake was deepest at the beginning of the holocene as a result of dead ice melting supply of melt water lowering of lake bottom and or precipitation increase change in atmospheric circulation during the boreal period the fall in water level takes place despite the opposite trend observed at nearby sites in addition the cladoceran data indicate an initial decrease in trophic conditions from mesotrophic to oligotrophic and then an increase to the mesotrophic state

biogeography of terminal cretaceous deep sea benthic foraminifera from the atlantic and pacific oceans abstract most species of late cretaceous deep sea benthic foraminifera are believed to be cosmopolitan and therefore to exhibit only minor biogeographical differences in this preliminary report six deep sea drilling project dspd sites from different oceans paleolatitudes and paleodepths were analyzed for terminal cretaceous abyssal bathyal benthic foraminifera in order to investigate their assumed cosmopolitan distribution and the question of whether different faunal compositions are related to time different paleolatitudes and or different paleodepths the material studied was obtained from the low latitude site 465 pacific ocean and the intermediate latitude sites 384 north atlantic and 356 516 525 and 527 south atlantic the material analyzed represents a time slice encompassing the last 20 50 k y of the cretaceous the faunas contain numerous velasco type species such as gavelinella beccariiformis white cibicidoides velascoensis cushman nuttallides truempyi nuttall gaudryina pyramidata cushman and various gyroidinoids and buliminids the results contradict the general assumption of the cosmopolitan nature of late cretaceous deep sea benthic foraminifera advocated in the literature only about 9 of the taxa identified were found to be truly cosmopolitan through their occurrence at all the sites analyzed on the basis of correspondence analysis and relative abundance data three assemblages and three subassemblages were recognized 1 a bathyal abyssal assemblage nuttallinella sp a cibicidoides hyphalus fisher valvalabamina sp evolute form and gyroidinoides spp at the south atlantic sites 356 516 525 and 527 divided into three subassemblages namely a a middle bathyal subassemblage eouvigerina subsculptura mcneil and caldwell tritaxia aspera cushman and g pyramidata at sites 516 and 525 b a lower bathyal subassemblage osangularia sp pyramidina rudita cushman and parker and quadrimorphina camerata brotzen at site 356 and c an abyssal subassemblage gyroidinoides sp c hyperammina bathysiphon gyroidinoides beisseli white and globorotalites sp b at site 527 2 an abyssal assemblage buliminella cf plana cushman and parker and bulimina incisa cushman at the north atlantic site 384 and 3 a middle bathyal assemblage vulvulina sp a osangularia navarroana cushman alabamina sp bulimina velascoensis cushman spiroplectammina spp calcereous forms and bulimina trinitatensis cushman and jarvis at the pacific site 465

dinoflagellate cysts sea level changes and planktonic foraminifers across the cretaceous tertiary boundary at el haria northwest tunisia abstract dinoflagellate cysts and planktonic foraminifers have been studied from the cretaceous tertiary k t boundary interval at el haria northwest tunisia a high resolution integrated biostratigraphy is presented the k t boundary is drawn at the level of extinction of cretaceous planktonic foraminifers and is coincident with the first occurrence of the dinoflagellate cyst species danea californica the final extinction of planktonic foraminifers is foreshadowed by a reduction in their total abundance some 5 kyr earlier at the base of the boundary clay this reduction is coeval with reported anomalies in siderophyle elements and 13 c values in the same area dinoflagellate cysts do not show accelerated rates of extinction at k t time associations of dinoflagellate cysts however change drastically and parallel changes in relative numbers of sporomorphs spores and pollen and in the quantity of land derived organic matter jointly these changes reflect a rapidly falling sea level during the final 17 kyr of the mesozoic which culminates at the level of the k t boundary this steep sea level fall at k t time represents a peak regressive pulse at the end of the well documented latest cretaceous regressive trend this short term sea level fall might show to be a wide spread phenomenon which could have caused an excess shrinking of the already reduced areal extent of marginal seas since deep waters in cretaceous oceans were primarily produced in shallow marginal seas the rate of formation of deep water might have been minimized at k t time minimum rates of formation of deep water might have curtailed the slow upward mixing of relatively cool and nutrient rich deeper water through which the thermocline weakened and surficial waters became depleted in nutrients consequently phytoplankton productivity rapidly diminished which in combination with a weakened thermal gradient pushed the highly depth stratified cretaceous planktonic foraminiferal fauna to extinction over a period of time of some 5 kyr guembelitria cretacea was the sole planktonic foraminifer which could accommodate to the low productivity conditions the oscillating rise in sea level at the beginning of the cenozoic reinforced the upward mixing of relatively cool and nutrient rich deeper water steepened the thermocline and replenished the photic layer with nutrients concomitant niche differentiation in the photic layer progressively stimulated morphological innovation amongst early cenozoic planktonic foraminifers the final return of normally sized planktonic foraminifers and of stable and well balanced dinoflagellate cyst associations at about 125 kyr after the k t boundary seems to indicate that primary productivity and niche differentiation in the photic layer begin to revert to optimum levels the earliest cenozoic planktonic foraminiferal species globoconusa minutula and parvularugoglobigerina fringa are thought to have developed from a benthic foraminiferal species rather than having a planktonic ancestry

morphological variation of emiliania huxleyi and sea surface salinity morphometric analysis of coccoliths of various coccolithophore species from core top and culture samples has revealed that the morphology of single placoliths can be affected by environmental parameters such as temperature salinity and productivity in this study we have tested the morphological variations of placoliths of emiliania huxleyi the most common coccolithophore species in the modern ocean with respect to environmental gradients we have investigated especially the potential effect of salinity on the morphology as it is known from culture studies that the growth of e huxleyi placoliths is strongly influenced by varying salinities morphometric analysis of about 2150 placoliths from 37 globally distributed core top and plankton samples revealed that the morphology of e huxleyi varies significantly along a sea surface salinity gradient from 33 to 38 morphological parameters such as the mean size of placoliths are used as explaining variables in multiple regression analysis to reconstruct sea surface salinities sss the best model for mean sss yields an r 2 of 0 88 with a standard error of 0 49 whereas statistical models describing surface water temperature or productivity are less reliable and accurate application of the best model to plankton samples allows the prediction of in situsalinitieswithingivenerrorestimates theapplicationofthebestmodeltofossilassemblagesfromthelgm however ismore puzzling paleosalinity reconstructions in the south atlantic the caribbean sea and the subtropical atlantic are in good agreement with the published values 2007 elsevier b v all rights reserved

a lateglacial and holocene organic carbon isotope record of lacustrine palaeoproductivity and climatic change derived from varved lake sediments of lake holzmaar germany abstract a composite varve dated 11 4 m long sediment sequence from lake holzmaar situated in the eifel region of western germany was investigated for total organic matter content total nitrogen content and stable organic carbon isotopes mean time resolution is 75 years for tn and 14 years for 13 c org on millennial time scales primary production of lacustrine algae strongly depends on the delivery of nutrients from the catchment the respective carbon isotope record is characterized by marked variations of 13 c org ranging from 36 0 to 27 0 and includes a number of pronounced shifts reactions of the lacustrine system and the catchment to changes of environmental parameters e g runoff solar radiation and temperature induce changes of algal associations and of lacustrine primary production which are reflected in the sediments as carbon isotope variations clear evidence of ecosystem reorganizations is detected by the carbon isotope record around 14 200 10 400 9600 5500 2700 1700 and 900 varve years bp in particular the holocene events of 9600 around 5500 and 2700 are interpreted as the expression of massive changes of the climate system the steady rise of 13 c org values during the mid holocene is interpreted as a continuous climatic amelioration reaching an optimum around 6500 varve years bp rapid and large changes of 13 c org values from 2700 varve years bp to the present indicate major disturbances in the catchment area these are most probably related to deforestation or reforestation and runoff changes presumably in conjunction with human impact carbon isotopes thus characterize the holzmaar ecosystem in time revealing lacustrine palaeoproductivity as well as providing palaeoenvironmental and palaeoclimatic information

antarctic marine temperatures late campanian through early paleocene an oxygen isotope paleotemperature study of benthic foraminifera from the upper campanian through lower paleocene section at seymour island near the coast of antarctica was done in conjunction with careful scanning electron microscope observations to monitor the state of foraminiferal preservation the isotopic compositions of those samples which were deemed to be well preserved were the basis of the conclusion that campanian through paleocene high latitude shelf waters near antarctica had temperatures between approximately 4 5 and 10 5 c temperatures during early and middle maastrichtian time were slightly higher than those of either the late campanian or late maastrichtian the inference of temperate climatic conditions in antarctica is in agreement with paleoclimatic conclusions drawn on the species composition of the planktonic foraminiferal assemblages and the character of the planktonic foraminifera as well as with published conclusions based upon paleobotanical evidence the maastrichtian and campanian water temperatures at seymour island are similar to those inferred from published isotope ratios of pacific late cretaceous benthic foraminifera from low latitudes indicating that campanian through early paleocene deep ocean waters at least in the pacific and perhaps elsewhere as well could have formed by sinking of surface waters in polar regions

enhanced carbon dioxide outgassing from the eastern equatorial atlantic during the last glacial biological productivity and carbon export in the equatorial atlantic are thought to have been dramatically higher during the last glacial period than during the holocene here we reconstruct the ph and co2 content of surface waters from the eastern equatorial atlantic ocean over the past 30 k y using the boron isotope composition of globigerinoides ruber a mixed layer dwelling planktic foraminifera our new record combined with previously published data indicates that during the last glacial in contrast to today a strong west to east gradient existed in the extent of air sea equilibrium with respect to pco2 pco2 with the eastern equatorial atlantic acting as a significant source of co2 100 atm while the western atlantic remained close to equilibrium 25 atm this pattern suggests that a fivefold increase in the upwelling rate of deeper waters drove increased atlantic productivity and large scale regional cooling during the last glacial but the higher than modern pco2 in the east indicates that export production did not keep up with enhanced upwelling of nutrients however the downstream decline of pco2 provides evidence that the unused nutrients from the east were eventually used for biologic carbon export thereby effectively negating the impact of changes in upwelling on atmospheric co2 levels our findings indicate that the equatorial atlantic exerted a minimal role in contributing to lower glacial age atmospheric co2

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

an analysis of recent deep sea benthic foraminiferal morphotypes from the norwegian and greenland seas abstract benthic foraminifera from 36 core tops from the norwegian and greenland seas have been placed into morphotype categories based on test shape nature of coiling and the presence or absence of wall pores these morphotypes have distinctive patterns with water depth and are related to species specific microhabitat preferences the morphotype data are used to reconstruct the water depth distribution of foraminiferal microhabitats in the region infaunal morphotypes exist predominantly in shallow water sediments 1500 m the morphological patterns documented in this study are similar to those observed on the southwestern continental margin of norway demonstrating that these patterns exist over a large part of the greenland and norwegian seas

late cretaceous upwelling system along the southern tethys margin israel interrelationship between productivity bottom water environments and organic matter preservation organic rich upper cretaceous sequences in israel were deposited in an extensive highly productive upwelling linked system which prevailed along the southern tethys margin and lasted for 19 m y santonian to late maastrichtian an understanding of the spatial and temporal characteristics of this system was gained through detailed paleontological and geochemical analyses of subsurface sequences in two basins in israel representing an outer shefela and an inner zin facies belt the nature of the upwelling system and its effect on the sedimentary record is related to two basic environmental parameters namely paleoproductivity intensity and oxygen levels at the bottom the assessment of these parameters and their interrelationship has been performed through the development of paleontological foraminiferal criteria which are independent of the organic matter content following the establishment of these criteria it is concluded that the productivity reached its maximum intensity during the late campanian which was also the time of most notable differentiation between the center of the upwelling system in the inner belt and the less intense conditions in the outer basin this distribution is expressed in varied lithology organic rich carbonates phosphorites and siliceous rocks at the core of upwelling and a uniform lithology organic rich carbonates at the margin of this system the uniform lithology of the maastrichtian in both basins composed of organic rich carbonates is ascribed to a gradual weakening of productivity the bottom conditions in the inner belt during the late campanian the time of maximum surface productivity were near anoxic changing to more aerated dysaerobic conditions during the early maastrichtian in the outer belt a more aerated bottom dysaerobic prevailed throughout the late campanian to late maastrichtian the elevated organic matter content in both basins reflects the overall environment of high productivity its actual variations however seem to be unrelated to changes in surface productivity and bottom oxygen levels

differential dissolution of upper cretaceous deep sea benthonic foraminifers from the angola basin south atlantic ocean abstract material from the deep sea drilling project dsdp site 527 from the angola basin south atlantic ocean has been analyzed to determine whether upper cretaceous benthonic foraminiferal taxa are differentially sensitive to calcite dissolution and if so to rank their order of susceptibility two regimes of dissolution established on the basis of the degree of planktonic foraminiferal fragmentation representing stronger and less prominent dissolution within the section studied were used as a framework for reference a total of 60 calcareous and eight agglutinated benthonic foraminiferal taxa were identified at the species or genus level of these twenty three calcareous and five agglutinated taxa were selected for the dissolution study relative abundance of each of the various taxa was tested statistically using t test between dissolution regimes to assess the significance of the change induced by increased dissolution nuttallides truempyi and neoeponides sp intermediate form are interpreted as resistant to dissolution pullenia spp alabamina sp a anomalina sp a praebulimina sp fusiform and nuttallinella sp a are susceptible to dissolution the majority of the taxa 16 in number are unaffected by dissolution because they show no change between dissolution regimes among the agglutinated taxa gaudryina pyramidata is resistant to dissolution whereas the remaining four taxa are unaffected by dissolution at the level of superfamilies one calcareous superfamily discorbacea is resistant two orbitoidacea and cassidulinacea are unaffected and two nodosariacea and buliminacea are susceptible to dissolution

paleooceanography of the mesogean sea based on ostracods of the northern tunisian continental shelf between the late cretaceous and early paleogene a new method analysis used in the study of the el kef section north western tunisia led to the paleooceanographic reconstruction of the mesogean between late cretaceous and early paleogene several changes observed are in fact worthy of particular mention paleobathymetrically the area changed from an upper bathyal environment of about 400 m deep to an outer shelf domain of 100 50 m furthermore the oxygen minimum zone o m z became highly intense at a the cretaceous tertiary transition catastrophic event b the p1 p2 boundary intense thermic stratification and c between p4 and p6 very active paleoproductivity in this last episode the continental shelf environment was subjected to intense upwelling responsible for the formation of a prephosphatic environment at water sediment interface the paleooceanographic history of phosphates in the gafsa metlaoui basin is in fact in perfect stratigraphic and paleoenvironmental agreement with the paleobathymetric evolution of the kef region finally paleooceanographic communication between the mesogean and the north atlantic was at this period highly free because of lack of hydrologic relations between the north atlantic and the norwegian sea

multiple deep water sources and trophic regimes in the latest cretaceous deep sea evidence from benthic foraminifera benthic foraminifera from 24 dsdp odp sites were investigated to assess their global horizontal and vertical distribution in the deep sea environment at the end of the cretaceous period the samples analyzed are from the late maastrichtian and within the planktic forammiferal abathomphalus mayaroensis zone from a wide range of oceans and paleolatitudes including the low latitude sites 10 and 384 atlantic ocean 47 171 305 and 465 pacific ocean the mid latitude sites 20 111 356 363 516 525 527 548 and 605 atlantic ocean 216 217 and 758 indian ocean and the high latitude sites 208 pacific ocean 689 698 700 738 and 750 southern ocean correspondence analysis based on the 75 most common taxa shows a clear biogeographic trend along the first correspondence axis by arranging the sites in paleolatitudinal order the assemblages from the tethyan realm i e low latitudes are marked by abundant heavily calcified buliminids such as bulimina incisa b trinitatensis b velascoensis and reussella szajnochae and aragonia spp whereas high latitude faunas are characterized by abundant alabamina creta gyroidinoides quadratus and pullenia coryelli the results indicate that the faunas at low and high latitudes respectively were influenced by quite different environmental conditions this is based on the much higher abundance of infaunal morphotypes at low and mid latitudes compared to high latitudes suggesting that the biogeographic trend found in the data set coincides with the trophic regime at the various sites the results also provide support for the hypothesis that postulates two simultaneous sources and mechanisms for deep water formation during the late cretaceous including warm saline deep water produced by evaporation at low equatorial latitudes in contrast to the formation of cold deep waters at high southern latitudes

benthic foraminiferal ecomarker species of the terminal cretaceous late maastrichtian deep sea tethys abstract benthic foraminiferal distribution patterns throughout the late maastrichtian tethyan deep sea are analyzed many species are ubiquitously distributed throughout this region and therefore it is hard to assess their ecological preferences however five species show distribution patterns which suggest that they may have distinctive paleoenvironmental preferences these preferences are interpreted from hypothesized surface circulation and upwelling patterns additional information comes from recent benthic foraminiferal ecology and from responses to the cretaceous paleogene k pg boundary event this enables us to assess the ecological preferences of these late maastrichtian taxa and establish them as ecological marker ecomarker species for paleoenvironmental interpretation of the late maastrichtian bathyal abyssal tethyan realm 1 eouvigerina subsculptura is suggested to be indicative of reasonably oxygenated upper middle bathyal environments though with high abundance of utilizable organic matter 2 sliteria varsoviensis is linked to areas of late maastrichtian upwelling and seems to have been an epibenthic species with an opportunistic life mode 3 gavelinella beccariiformis and 4 nuttallides truempyi are considered to be indicative of oligotrophic conditions unless they occur with a large proportion of endobenthic morphotypes 5 gavelinella pertusa is proposed to indicate neritic middle bathyal environments of the boreal realm which might be influenced by more seasonal food fluxes and by higher oxygen levels than similar settings in the sub tropics finally the anomalous high abundances of the buliminid species sitella cf plana in deep open ocean environments is discussed in terms of possible mechanisms permitting such a morphologically opportunistic species to thrive in such an assumedly oligotrophic environment

are mid latitude slopes sensitive to climatic oscillations implications from an early holocene sequence of slope deposits and buried soils from eastern germany abstract on a straight slope within the lake catchment of kleiner tornowsee brandenburg germany a sequence of slope sediments has been deposited during the late glacial the early holocene and around cal 4 2 ka before today 800 500 and 300 years ago the chronology is based on 21 radiocarbon dates and 11 osl dates and a deposition model including the numerical data as well as stratigraphic information has been calculated with oxcal 4 1 a comparison of the woody taxa of charcoal particles n 566 embedded within the sediments with the known regional vegetation history confirmed the reliability of the dates according to the age volume and distribution the deposition of the early holocene sediments at ca 10 3 kyrs ca 9 5 kyrs and ca 8 2 to 7 7 kyrs before today strongly suggests an influence of known climatic deteriorations phases on geomorphologic processes cold and dry climatic conditions probably promoted wildfires in pinus dominated forests and therefore triggered the observed repeated slope instability in consequence mid latitude slope deposits provide a potential to reconstruct the geomorphological response to climatic events at a high spatial resolution in contrast the recorded mid to late holocene soil erosion phases on the slope have been triggered by land use activities apart from traditional environmental archives slope deposits provide valuable information about the vegetation and climate history

a high resolution record of late glacial and early holocene climatic and environmental change in the czech republic abstract recent discovery of thick buried lake sediments in the t ebo basin south bohemia presents an exceptional opportunity to study the late glacial history of eastern central europe high resolution investigation of pollen plant macrofossils algal remains and lithology for the late glacial and early holocene sediments of former lake svarcenberk yielded a well founded palaeoclimatic and palaeovegetational data that can be compared with the results from other parts of a west east european transect taking into account the oceanic continental gradient and its influence for palaeoenvironmental conditions the results demonstrate that the effect of north atlantic oceanic changes during the last glacial interglacial transition extended to the investigated area nevertheless significant differences in timing intensity and character of vegetational response to these climatic changes have been found between the area under study and the western part of central europe these differences can be ascribed to increased seasonality specific regional mesoclimatic and soil conditions and possible local glacial refugia for pine the results of sediment chemical analyses indicate a close correspondence between climatic vegetational and soil development in lake catchments

stable isotope toc and caco3 record across the cretaceous tertiary boundary at el kef tunisia we report the results of stable oxygen and carbon isotope analysis of carbonate fine fraction and benthic and planktic foraminifers caco3 and toc determinations of sediments across the cretaceous tertiary k t boundary at el kef tunisia we used grain size analysis of the fine fraction carbonate to determine possible compositional effects and smearslide and scanning electron microscope examinations to evaluate possible diagenetic alteration and microfossil preservation the data suggests the following sequence of events upper maastrichtian oxygen and carbon isotope signals indicate relatively warm temperatures a decreasing thermal gradient possibly related to a shallowing sea and relatively high surface water productivity a sharp cooling appears to begin just below the k t boundary the k t boundary is characterized by a sudden 2 negative shift in fine fraction 13c a slight 0 6 enrichment in benthic 13c and a reduction of about 40 in caco3 sedimentation these data imply strongly reduced surface water productivity as also observed in numerous deep sea sequences worldwide the lower danian planktic foraminiferal zones p0 p1a is marked by generally low productivity and unstable environmental conditions as indicated by generally low but fluctuating fine fraction 13c values and low 5 15 carbonate deposition at the base of subzone p1b caco3 benthic and fine fraction 13c values increase gradually and reach near pre k t boundary levels in subzone p1c indicating initial recovery after the k t boundary event about 300 000 400 000 years after the k t boundary the prolonged low productivity episode after the k t crisis and the pre k t boundary cooling associated with a major reduction in planktic foraminiferal diversity are difficult to explain by a single k t boundary bolide impact

deep circulation in the late cretaceous oxygen isotope paleotemperatures from inoceramus remains in d s d p cores abstract inoceramus is an epibenthic bivalve which lived in a wide variety of paleoenvironments encompassing a broad range of paleodepths a survey of all cretaceous sediments from deep sea drilling project legs 1 69 and 75 revealed over 500 inoceramus specimens at twenty sites of these 47 well preserved late cretaceous specimens from the south atlantic pacific and indian oceans were analyzed for oxygen and carbon isotopes the specimens exhibit small internal isotopic variability and oxygen isotopic paleotemperatures that are consistent with a deep sea habitat paleotemperatures ranging from 5 to 16 c show that late cretaceous oceans were significantly warmer than the present oceans the data suggest that deep water was formed both by cooling at high latitudes and by evaporation in the subtropics

freshwater ostracods crustacea from the lateglacial site at miesenheim germany and temperature reconstruction during the meiendorf interstadial abstract combined investigations of ostracod communities pollen and stable isotopes were carried out on lateglacial limnic high resolution sediment sequence from miesenheim in germany the pollen data confirm the presence of meiendorf interstadial the first interstadial after the pleniglacial the former shallow lake was formed at the end of the pleniglacial and partly dried out between the bolling and the allerod lake laach tephra 12 880 warve yr bp marks the top of this profile the intensive colonization with ostracods at the beginning of the meiendorf interstadial is characterized by great instability of their populations only ostracods from the upper littoral zones of lakes ponds or temporary pools were found the stable isotope data 18o 13c of the valves of the cypridopsis vidua herpetocypris reptans and candona candida reflect the different microhabitats of these three species and show a general climatic development during the meiendorf interstadial with two summer temperature peaks one at the beginning and a weaker one in the second half of the meiendorf interstadial

a low extinction rate of intermediate water benthic foraminifera at the cretaceous tertiary boundary the contrast between the high extinction rates of calcareous marine plankton and low extinction rates of deep water calcareous benthic foraminifera across the cretaceous tertiary k t boundary is now recognized however the water depth at which the vertical change in extinction rates of marine organisms occurred at the k t boundary is not yet known because of the lack of data on the extinction rates of intermediate water organisms the extinction rate of intermediate water benthic foraminiferal species from kawaruppu hokkaido japan was determined by distinguishing locally extinct species a distinctly low extinction rate 10 for calcareous benthic foraminiferal fauna from the upper part of the intermediate water is documented for the first time this rate is almost equal to the extinction rate of deep water benthic foraminifera 10 and is much smaller than the planktic foraminiferal extinction rate 81 the extinction rate curve for calcareous foraminifera in a vertical water column indicates that a rapid change from a high extinction rate 80 to a low extinction rate 10 took place at a water depth of about 150 m this depth of change is equivalent to the boundary depth between the surface and intermediate waters and between the euphotic and aphotic zones furthermore this coincidence is consistent with the hypothesis that acid rain and a darkness induced breakdown of the marine food chain produced by a cometary or asteroidal impact at the k t boundary were the main causes of the mass extinction of calcareous planktic organisms in surface waters

late glacial and holocene history of former salziger see central germany and its climatic and environmental implications an 8 40 m long sediment sequence from the salziger see basin central germany was investigated by a multi disciplinary approach including chronological sedimentological geo and biogeochemical methods radiocarbon dating conducted on ten samples of aquatic and terrestrial fossil remains and the occurrence of the laacher see tephra lst reveal that the sediment sequence comprises the late glacial and holocene lake history since ca 13 800 cal year bp this onset of lacustrine sedimentation is almost 7 000 years earlier as assumed so far the geo and biogeochemical data indicate distinct variations throughout the late glacial which can be correlated with cold and warm periods such as the oldest dryas the bolling the allerod and the younger dryas during most of the holocene minor variations in the geo and biogeochemical data and a high carbonate content due to the formation and precipitation of autochthonous carbonate in the lake indicate relatively stable lacustrine conditions a slight change in the sedimentary conditions between 6 700 and 4 000 cal year bp with lower deposition of carbonate and fine material can be traced back to enhanced subrosion in the basin increased deposition of coarser sediments and a high accumulation of heavy metals document intensive human activity in the region during the past ca 1 000 years

ecological and temperature controls on mg ca ratios of globigerina bulloides from the southwest pacific ocean we present mg ca data for globigerina bulloides from 10 core top sites in the southwest pacific ocean analyzed by laser ablation inductively coupled plasma mass spectrometry la icpms mg ca values in g bulloides correlate with observed ocean temperatures 7 degrees c 19 degrees c and when combined with previously published data an integrated mg ca temperature calibration for 7 degrees c 31 degrees c is derived where mg ca mmol mol 0 955 x e 0 068 x t r 2 0 95 significant variability of mg ca values 20 30 was found for the four visible chambers of g bulloides with the final chamber consistently recording the lowest mg ca and is interpreted in part to reflect changes in the depth habitat with ontogeny incipient and variable dissolution of the thin and fragile final chamber and outermost layer concomitantly added to all chambers caused by different cleaning techniques prior to solution based icpms analyses may explain the minor differences in previously published mg ca temperature calibrations for this species if the lower mg ca of the final chamber reflects changes in depth habitat then la icpms of the penultimate or older chambers will most sensitively record past changes in near surface ocean temperatures mean size normalized g bulloides test weights correlate negatively with ocean temperature t 31 8 x e 30 5xwtn r 2 0 90 suggesting that in the southwest pacific ocean temperature is a prominent control on shell weight in addition to carbonate ion levels

the influence of microhabitats on the carbon isotopic composition of deep sea benthic foraminifera we report 13c and 18o values for rose bengal stained benthic foraminifera from a set of box cores from continental margin environments in the atlantic and pacific oceans these isotopic results are compared with foraminiferal distribution data and pore water 13c profiles to evaluate the importance of environmental microhabitat effects on the carbon isotopic composition of benthic foraminifera the 13c values of infaunal taxa are consistently lower than those of epifaunal taxa suggesting that microhabitat effects on test composition do exist the 13c differences between foraminiferal carbonate and bottom water dissolved inorganic carbon are not correlated with the 18o differences between benthic foraminifera tests and equilibrium calcite but they do correlate with variations in the chemistry of sediment pore waters however interspecific 18o differences as well as 13c differences between species with similar vertical distributions in the sediments indicate that taxon specific vital effects also influence test composition

paleocology of late maastrichtian heterohelicidae planktic foraminifera from the atlantic region abstract late maastrichtian planktic foraminiferal heterohelicidae from deep sea drilling project sites in the northwestern atlantic 111 and 605 the south atlantic 356 and 357 and from mediterranean land sections near e1 kef tunisia and caravaca spain show two bioprovinces site 111 has transitional heterohelicid faunas in which a few heterohelix species dominate while the other localities have diverse tethyan faunas a quantitative analysis allows for a more detailed subdivision within the tethyan faunas heterohelicid species occur in different relative frequencies at the south atlantic the north atlantic and the mediterranean localities the south atlantic dsdp sites contain heterohelix rajagopalani govindan in addition to all other tethyan species the faunas from the two mediterranean sections are comparable however the overall diversity at el kef is the lowest of all tethyan sections and the area is interpreted as representing paleo upwelling the otherwise diverse faunas from the north atlantic site 605 contain some transitional elements which suggests mixing with cooler surface waters possibly derived from a proto labrador current

atmospheric circulation upwelling and organic rich rocks in the mesozoic and cenozoic eras abstract by using the basic principles of atmospheric circulation and analogies from present circulation patterns it is possible to construct qualitative atmospheric circulation models on paleogeographic maps the wind patterns predicted by these models then serve as the basis for predicting the locations of ancient upwelling zones atmospheric circulation and upwelling models for seven geologic stages in the mesozoic and cenozoic were constructed and the distribution of the upwelling zones compared with the distribution of organic rich rocks for all time periods together the correlation was statistically significant when the individual time periods were analyzed separately the following pattern emerged significant correspondence between upwelling zones and organic rich rocks in the triassic middle early cretaceous to late cretaceous and middle paleogene to neogene no significant correspondence was found for the intervening times upwelling does not account for all organic rich rocks so called anoxic oceanic events and transgressions play an important role in their deposition it is suggested that upwelling contributes significantly to the pattern of organic rich rock distribution and is important in determining organic facies

late glacial climatic oscillations as recorded in swiss lake sediments regional pollen assemblage zones for the late glacial period of the swiss plateau are introduced and defined they include four major zones artemisia juniperus hippophae betula pinus paz with several subzones pollen and oxygen isotope analyses on lacustrine sediments from several lakes in the area reveal four distinct phases of climatic oscillation in the time period of 13 000 9500 yr bp the first oscillation termed the aegelsee fluctuation occurs shortly before 12 000 yr bp and varve counts suggest its duration was ca 100 yr it is characterised by a short decrease in the oxygen isotopes as well as a short increase in nap associated with a depression in birch pollen values the second oscillation which occurs in the 18o record shortly before the deposition of the laacher see tephra ca 11 000 yr bp is termed the gerzensee fluctuation it occurs during a pine dominated phase and its vegetational effects cannot be determined palynologically the most prominent regressive phase is the younger dryas biozone ca 10 700 10 000 yr bp characterised by an increase in heliophilous nap and low 18o values the younger dryas biozone can often be subdivided palynologically into two parts a first part rich in grasses and juniper and a second part with higher filipendula and birch values during the preboreal biozone another distinct oscillation is evidenced only in the oxygen isotope ratios comparison of the swiss oxygen isotope profiles with the greenland dye 3 record suggests that not only the three major shifts in the 18o curves but also the minor ones are closely comparable suggesting some common climatic control

calcareous nannofossils as paleoproductivity indicators in upper cretaceous organic rich sequences in israel abundant and diverse calcareous nannofossil assemblages were found in organic rich carbonate sequences which accumulated in a campanian maastrichtian upwelling belt along the southeastern tethys the sequences studied represent the inner shallower and the outer deeper parts of the upwelling belt the paleoenvironmental significance of selected nannofossil taxa and their utility in productivity reconstruction was established by comparing their distribution to foraminifera and dinocyst based productivity profiles based on the calcareous nannofossil assemblages a high productivity group and a low productivity group of species were determined the distribution of these groups agrees well with the dinocyst and foraminifera based productivity curves and hence can be used to record paleoproductivity changes the ratio between the high productivity and low productivity nannofossil groups the nannofossil index of productivity nip is proposed here as a productivity proxy that can be utilized in reconstructing basinal productivity development a quantitative analysis of the nannofossil assemblages indicates that their abundance and diversity increase towards the open sea in the outer and less productive part of the upwelling belt in the inner and more productive part of the upwelling belt the nannofossils assemblages become less abundant and less diverse relative to those of the open marine environment micula decussata and watznaueria barnesae are common to abundant in most samples m decussata becomes more abundant in poorly preserved samples on the other hand the distribution of w barnesae matches better with intermediate productivity levels

numerical climate modeling a frontier in petroleum source rock prediction results based on cretaceous simulations organic productivity and preservation are primary controls of the distribution of petroleum source beds both organic productivity and preservation are in part a function of geographic setting and climate therefore the prediction of paleoclimates is a major frontier in petroleum source rock prediction a climate model based on the fundamental laws thought to govern atmospheric circulation is applied here to the prediction of upwelling regions associated with very high productivity and bottom conditions that may become anoxic despite a high oxygen supply the potential and limitations of climate modeling in the prediction of upwelling regions are examined by 1 demonstrating the ability of the model to predict present day winds and upwelling regions 2 demonstrating t at the model and the location of upwelling regions is sensitive to geography continental positions sea level and topography and 3 investigating whether the model sensitivity to past geographies is realistic i e if predicted upwelling regions for the cretaceous period correspond to source rock localities the model predictions of ocean and coastal upwelling compare very favorably with present day observations and with estimates of primary productivity the location of middle latitude and high latitude upwelling locations are sensitive to model specified geography the location of low latitude upwelling is less sensitive to changes in global geography if coastlines are oriented appropriately despite some limitations a comparison of source rock localities with model predictions is promising the results of these studies suggest that numerical climate modeling is a potential tool in petroleum source rock prediction

lateglacial to late holocene landscape history derived from floodplain sediments in context to prehistoric settlement sites of the southern foreland of the harz mountains germany abstract the harz mountains are germany s northernmost low mountain range the southern foreland is characterised by a fragmentary distribution of loess and loess like deposits during prehistoric times this region was sparsely populated in contrast to the adjoining southern floodplain of the helme river which has been a favoured settlement area since the neolithic period this study focusses on the onset of human impact on the landscape and aims to reconstruct the landscape development of this peripheral prehistoric settlement area under a long term perspective lateglacial to late holocene the study is based on the sedimentological analysis of six sediment profiles from the floodplain of two small valleys the chronology of the sedimentological records is provided by 24 new ams radiocarbon ages that range from 21 7 ka bp to 0 1 ka bp three major changes in the depositional environment are observed in the sediment records representing the landscape evolution a during the lateglacial periglacial conditions prevailed and deposition and reworking of loess occurred on the slopes while in the floodplains periglacial cover beds and alternating partly gravelly layers of silts and clays were deposited b from preboreal to atlantic periods a marked rise in the groundwater table led to authigenic precipitation of carbonates in the floodplains under ameliorated climatic conditions during this phase the valleys were progressively filled by intercalated organogenic and calcareous sediments c human influence on the landscape is reflected in colluvial and alluvial deposits indicating the occurrence of human induced soil erosion and is dated prior to the beginning of the bronze age here corresponding to subboreal period during the period of the little ice age gully incision occurred probably as a result of an intensified land use in upslope areas and of high magnitude precipitation events during this period

late glacial early holocene environmental changes in thuringia germany stable isotope record and vegetation history abstract the 7 m thick sediment profile at plinz in northern thuringia central germany covering the time span between 10 000 and at least 8000 14 c years bp about 11 600 9000 cal bp was studied using radiocarbon stable isotopes and pollen analysis the results reflect the very fast climatic transition from the late glacial to the holocene as a change from cold and dry to warmer and wetter conditions a short climatic deterioration during the preboreal oscillation pbo at around 9800 14 c years bp is clearly reflected by a sharp drop in the pinus concentration accompanied by a considerable increase in betula salix various herbs and the distinct occurrence of aquatic plants during the preboreal stable isotopes of biogenic carbonate show several episodes with altered levels of atmospheric moisture continuous climatic improvement without any oscillations can be suggested for the period covering the end of preboreal and the boreal

varve chronology and palynology of the lateglacial in northwest germany from lacustrine sediments of hamelsee in lower saxony abstract the hamelsee is a dolina from a collapse over permian salt that occurred at the end of the pleniglacial it is more than 21 m deep and contains 18 m of lacustrine sediments the lateglacial sediments in the central part of the lake consist of 2 7 m from 15 to 17 7 m of sapropelic and silty muds which are mostly laminated and partly bioturbated minor slumps occur mainly during colder phases the subdivision of the lateglacial is based on pollen zones multidisciplinary studies of the microfacies from thin sections geochemistry pollen analysis and rotifer analysis allow environmental and palaeoclimatological interpretations to be made the biozones of the lateglacial and their boundaries are marked by rapid climatic changes though covering comparatively short periods of time they are not monotonous but characterized by minor internal climatic fluctuations the sediments of the meiendorf and oldest dryas are not laminated the allerod sediment is seasonally varved without interruption and encompasses 625 yr the eruption of the laacher see volcano 12 900 cal bp had an impact on the climate during the following 10 yr the transition from the allerod to the younger dryas took some 50 yr and it occurred 200 yr after the eruption of the laacher see volcano the abrupt change at the end of the lateglacial 11 560 cal bp occurred within less than 10 yr however many proxies reacted with a time lapse of 15 to 30 yr

late glacial and early holocene changes in vegetation and lake level at hauterive rouges terres lake neuchâtel switzerland palynological and sedimentological analyses of a sedimentary sequence sampled at hauterive rouges terres lake neuch tel switzerland provide documentation of changes in vegetation and lake level during the bolling younger dryas and preboreal pollen zones and have allowed a comparison with sequences covering the same period from other sites located in the western part of the swiss plateau the juniperus hippophae zone regional pollen assemblage zone rpaz chb 2 first part of the bolling ca 14 650 14 450 cal yr bp was characterised by a generally low lake level a weak rise occurred during this zone the juniperus hippophae to betula zone transition coincided with a lake level lowering interrupted by a short lived but marked phase of higher lake level recorded at the neighbouring site of hauterive champreveyres but not present at hauterive rouges terres owing to an erosion surface shortly after the beginning of the betula zone rpaz chb 3 second part of the bolling ca 14 450 14 000 cal yr bp a marked rise in lake level occurred it was composed of two successive periods of higher level coinciding with high values of betula separated by a short episode of relatively lower lake level associated with raised values in artemisia and other non arboreal pollen the last part of rpaz chb 3 saw a fall in lake level the lower lake levels during rpaz chb 2 to early rpaz chb 3 can be correlated with the abrupt warming at the beginning of the greenland interstadial gi 1e thermal maximum the successive episodes of higher lake level punctuating the gi 1e might be linked to the so called intra bolling cold oscillations identified from several palaeoclimatic records in the north atlantic area and also documented in oxygen isotope data sets from swiss plateau lakes the hauterive rouges terres lake level record provides evidence for marked climatic drying through the second part of the younger dryas event gs1 during the gs1 preboreal rpaz chb 4b 4c transition except for a rise at ca 11 450 11 400 cal yr bp and at the rpaz chb 4c 5 preboreal boreal transition following the preboreal oscillation after 11 150 cal yr bp the preboreal oscillation coincided with higher lake levels its end being followed by a rapid expansion of corylus quercus ulmus and tilia the hauterive rouges terres lake level record suggests that radiocarbon plateau at 12 600 10 000 and 9500 14c yr bp corresponded to periods of generally lower lake level this suggests that an increase in solar activity may have contributed to both climatic dryness and a decrease in atmospheric radiocarbon content copyright 2002 john wiley sons ltd

late pleistocene to early holocene natural and human influenced sediment dynamics and soil formation in a 0 order catchment in sw germany palatinate forest this paper presents the dynamics of sedimentation processes and soil development of a steeply sloping 0 order catchment in the sandy lower bunter of the south western mid range mountains in the palatinate forest germany during the transition period from the late glacial to the early holocene field investigations chemical physical micromorphological and anthracological analyses revealed a complex palaeosol sediment sequence along the thalweg of a dry valley where a significant amount of the sediment from the adjacent slopes had been captured the deposition of aeolian sands in the lowermost sediment layer took place in the early late glacial the subsequent sediments were deposited by slope wash and aeolian processes it contains a higher amount of silt and dates from the allerod the occurrence of laacher see tephra lst indicates that this sediment has been near the surface around 12 900 cal bp it also shows characteristics of palaeosols similar to the usselo finow soils in north eastern germany in the overlying material the amount of root remnants other organic matter and rounded bone fragments possibly indicates the presence of people in this area on top alternating reddish brown coarse to fine sand and small partly rounded stones with some small intercalated aggregations of humic material rich in charcoal dating to between 11 000 and 12 000 cal bp were deposited the layers are overlain by clearly visible and evenly distributed wavy clay illuviation bands typical for a luvisol in the upper metre a cambisol has developed the sediment structure shows typical features of a flash flood event in the preboreal the stratigraphy suggests that phases of sedimentation caused by water and aeolian erosion took place in the allerod younger dryas and preboreal discussion considers climate driven natural processes as well as the possibility that the manipulation of forest vegetation by fire through sedentary mesolithic hunter gatherer groups created open areas and enabled intensive soil erosion at a local scale

the preboreal oscillation around the nordic seas terrestrial and lacustrine responses the occurrence of an early preboreal climatic cooling oscillation pbo in lacustrine and glacial records from northwest europe iceland and greenland is reviewed and documented the often subtle response of the proxy records to this oscillation in combination with its short duration make it difficult to detect owing to its chronostratigraphic position between the 10 000 9900 and 9600 9500 14 c plateaux c 11 300 11 150 calendar yr bp it is also difficult to 14 c date with precision we find that the vegetation response to the pbo varies between sites and regions in contrast to the pioneer vegetation in iceland and southern sweden the expanding birch pine forest in germany denmark was more susceptible to deteriorating growing conditions the combined lacustrine tree ring and glacial records imply that the pbo was characterised by cool and humid conditions throughout northwestern and central europe this is documented by vegetation changes decreased aquatic production increased soil erosion increased 2 h and 13 c content in tree rings readvances or stillstands of the ice sheet in norway and finland and ingression of brackish water into the baltic icelandic proxy records from lake sediments and glacial moraines imply cooler conditions than during the previous preboreal period but not as extreme as during the younger dryas greenland records suggest that the early preboreal was characterised by ice readvances as an effect of cool climate and increased precipitation in relation to the younger dryas it was not until the end of the pbo that climate was warm enough to melt the land based ice sheet this preboreal oscillation found on both sides of the nordic seas is interpreted as an effect of increased freshwater forcing on the thermohaline circulation in the nordic seas which is implied by a simultaneous and distinct rise in the atmospheric 14 c 12 c ratio a slow down of the thermohaline circulation may tempor arily have pushed the polar front further south 1997 by john wiley sons ltd preboreal oscillation thermohaline circulation lacustrine records glacial records chronology

controls on shell mg ca and sr ca in cultured planktonic foraminiferan globigerinoides ruber white mg ca and sr ca ratios were determined on a single species of planktonic foraminiferan globigerinoides ruber white collected from the gulf of eilat and cultured in seawater at five different salinities 32 to 44 five temperatures 18 to 30 c and four ph values 7 9 to 8 4 the mg ca temperature calibration of cultured g ruber with an exponential slope of 8 3 c agrees well with previously published calibrations from core tops and sediment traps however the dependence of mg ca on salinity with an exponential slope of 5 3 psu is also significant and should be included in the calibration equation with this purpose we calculated a calibration equation for g ruber dependent on both temperature and salinity within the 95 confidence limits mg ca mmol mol exp 0 06 0 02 s psu 0 08 0 02 t c 2 8 1 0 r2 0 95 the influence of ph on mg ca ratios is negligible at ambient seawater ph 8 1 to 8 3 however we observe a dominating ph control on shell mg ca when the ph of seawater is lower than 8 0 sr ca in g ruber shows a significant positive correlation with average growth rate presumably part of the variability in shell sr ca in the geological record is linked to changes in growth rates of foraminifera as a response to changing environmental conditions

benthic foraminiferal fauna during the time of the indian asian contact in southern balochistan pakistan cretaceous and early paleocene benthic foraminifera were studied from one section along the western gaj river southern balochistan pakistan to reconstruct the paleoenvironment of the tethys sea during the indian asian contact we recognize three lithostratigraphic units in ascending order the mughal kot formation the pab sandstone and the jamburo group both the maastrichtian mughal kot formation which consists of shale with grey marly limestone and the maastrichtian pab sandstone which consists of quartzose sandstone indicate an open ocean environment as they have diversified planktic and benthic foraminiferal assemblages the maastrichtian paleocene jamburo group consisting of dark grey calcareous shale and marlstone with some sulfide grains is characterized by low diversities of benthic assemblages the change to the lower diversities may be associated with the development of poor circulation of deeper water that was caused by narrowing of the tethys sea the trochammina spp assemblage from the jamburo group which can be correlated with flysch type agglutinated foraminiferal assemblages has a low benthic species diversity indicating an unfavorable condition for calcareous foraminifera because of the development of oxygen depleted water the absolute abundance of agglutinated specimens shows a remarkable change from low numbers in the maastrichtian to high ones in the paleocene the benthic foraminiferal evidence supports the hypothesis that the collision of the asian and indian plates occurred near the end of the cretaceous

ice core evidence of abrupt climate changes ice core records show that climate changes in the past have been large rapid and synchronous over broad areas extending into low latitudes with less variability over historical times these ice core records come from high mountain glaciers and the polar regions including small ice caps and the large ice sheets of greenland and antarctica

reaction of the lake environment to the holocene warming depending on the distance to the maximum extent of the vistulian ice sheet abstract this study presents 1 the results of a stable isotope and subfossil cladocera analyses of lacustrine sediments from maliszewskie lake e poland and next 2 different reaction of the lake environments depending on the lake s localization maliszewskie lake is located in north podlasie lowland ca 30 km to the south of the vistulian ice sheet limit the approximately 4 80 m thick sediments maliszewo i profile are mainly comprised of calcareous gyttja covered by peat and organic detritus gyttja pollen analysis documents that the sediments accumulated from the late glacial allerod period to recent times based on the results of stable isotope and subfossil cladocera analyses of sediments the lake environmental changes were reconstructed a positive trend in 18o and 13c values documents a gradual climatic warming the fluctuations of the oxygen isotopic values suggest the multiple oscillation of water level due to a change in the evaporation precipitation ratio the subfossil cladoceran fauna in the maliszewo i profile is represented by 21 species belonging to five families three zones of cladocera development were distinguished the cladocera species indicate the initial oligotrophic status of the lake and its subsequent increase of trophic status currently maliszewskie lake is a very shallow declining reservoir the initial period of its existence probably saw its maximal depth in presented studies we compared our results with data from three other sites documenting the reaction of the lake environment during the late glacial and holocene transformation at that time we observed different reactions to the climate amelioration in the northern postglacial lakes the holocene warming at first provoked an input cold melting water characterized by more negative oxygen isotope values and then a rise in water temperature in the lakes further away from the glaciation border periglacial lakes the increase in water temperature documented by e g more positive oxygen isotopic immediately occurred the climate warming is commonly manifested by a significant increase of number of species and individuals of cladocera

the effect of sea surface properties on shell morphology and size of the planktonic foraminifer neogloboquadrina pachyderma in the north atlantic abstract the variability in size and shape of shells of the polar planktonic foraminifer neogloboquadrina pachyderma have been quantified in 33 recent surface sediment samples throughout the northern atlantic ocean and correlated with the properties of the ambient surface waters the aim of the study was to determine whether any of the morphological features could be used to reconstruct sea surface properties in the polar realm of the north atlantic where most paleotemperature proxies appear to fail the analyses revealed that shell morphology is only weakly controlled by habitat properties whereas shell size showed a strong correlation with sea surface temperature the regression of mean shell size on sea surface temperature revealed the presence of two trends among the sinistrally coiled shells a continuous increase in shell size with decreasing sst in sediments deposited under polar water masses and a continuous increase in shell size with increasing sst in samples from transitional waters the second trend mirrors the trend observed for dextrally coiled shells which are frequent in the same samples and signal the presence of n incompta the identical mean shell size trends among the sinistral and dextral specimens in the temperate samples confirms the results of earlier genetic studies which indicated the existence of a small but distinct proportion of opposite coiling in n incompta to which the sinistral shells in the temperate samples could be attributed the linear correlation between mean shell size and sea surface temperature in the polar domain summer sst

natural transformation of the romoty paleolake ne poland during the late glacial and holocene based on isotopic pollen cladoceran and geochemical data abstract romoty is the name of a sediment profile from the overgrown lake located in elk lakeland ne poland the sediment core which is 8 4 m in length documents the development of the reservoir since the melting of dead ice and formation of the lake basin i e before 13 000 years bp until it became overgrown with plants the characteristics of the sediments changed from mineral deposits on the bottom silty sands to biogenic deposits consisting of dark olive calcareous detritus gyttja and light calcareous gyttja with increasing carbonate content and to peat in the upper part based on the data chemical stable isotopes subfossil cladocera remains pollen we have distinguished three main stages of the evolution of romoty paleolake the first stage includes the formation of the lake basin in the late glacial and early holocene preboreal the second stage is characterized by the harmonic natural development of the romoty paleolake from the boreal to subboreal this stage coincides with a period of climatic warming and biogenic sediments accumulated in this reservoir at that time the third stage concerns the disappearance of the lake in the late holocene subatlantic the lake conditions declined and the reservoir completely filled with sediments and has transformed into a mire the characterization of each stage involves a description of environmental conditions occurring in the romoty paleolake particularly the cladocera community the chemical composition the temperature and trophy of the water the water level the nature of bottom sediments and the plants occurring in the reservoir and its surroundings the lowest water temperature occurred in the late glacial and preboreal periods since the boreal period gradual warming is observed and is expressed through a positive trend in both 18 o and 13 c and changes in both cladocera and plant compositions the lake was deepest at the beginning of the holocene as a result of dead ice melting supply of melt water lowering of the lake bottom and or increased precipitation change in atmospheric circulation the water level fell during the atlantic period additionally the cladoceran and non pollen palynomorph data indicate low trophy followed by an increase in the mesotrophic state human impact was documented only by a low occurrence of pollen grains of cerealia in the youngest sediments subatlantic period suggesting a low penetration by human groups of the area near the romoty paleolake

calcareous nannofossil and dinoflagellate stratigraphy across the cretaceous tertiary boundary at hor hahar israel in israel the cretaceous tertiary k t boundary at hor hahar occurs within the interval from the top of the ghareb formation maastrichtian to just below the horizon of dark marl and clay within the overlying taqiye formation paleocene the studied interval contains all the calcareous nannofossil zones micula prinsii latest maastrichtian markalius inversus np1 earliest paleocene andcruciplacolithus tenuis np2 early paleocene they correlate in sequence with theabathomphalus mayaroensis p0 p1a p1b and p1c planktic foraminiferal zones the palynological assemblages consist mainly of dinocysts with only few pollen grains and spores these assemblages are used to interpret five stratigraphic phases of environmental change across the k t boundary in the hor hahar section in the latest maastrichtian there is an overwhelming dominance of the nannofossilmicula decussata which probably reflects environmental stress preceding the terminal cretaceous mass extinction a nearshore marine environment at the boundary is suggested by the increase in number of specimens of the dinocystcyclonephelium and by the predominance of terrigenous organic matter sediment there followed two episodes of transgression and regression the calcareous cyst producing dinoflagellatethoracosphaera futterer 1976 becomes dominant in two episodes at the boundary and approximately one meter above it it alternates in abundance with the organic walled dinoflagellates which suggests that different environmental parameters were operating for each group maastrichtian dinocysts decline in abundance toward the k t boundary they reach greatest abundance and species diversity at the same strata where foraminiferids recover after their mass extinction at the boundary calcareous nannofossils recover only later in the early paleocene changes in 13c and total organic carbon as as well as dinocyst and nannofossil composition indicate an episode of strong ecological stress about one meter above the boundary

very fast environmental changes at the pleistocene holocene boundary recorded in laminated sediments of lake gościz poland abstract this paper presents a reconstruction of the climatic changes at the pleistocene holocene transition recorded in the annually laminated sediments of lake go ci a z poland this reconstruction is based on pollen stable isotope mineralogical and chemical analyses of sediments made with a time resolution of 1 4 yr it reveals a sequence of abrupt climatic changes which preceded and followed the major warming around 11 500 cal bp our data show that the warming period was preceded by a 30 yr long phase of increased winter and decreased summer precipitation 11 550 11 520 cal bp about 11 520 cal bp a very brief period of wetter conditions occurred simultaneously with the beginning of the major warming however most of the first phase of the major warming 11 520 11 500 cal bp was characterised by a generally dry climate presumably due to lowered winter precipitation our records suggest that in this phase the warming concerned winter seasons mostly in the second phase 11 500 11 460 cal bp the warming also concerned summer seasons also a distinct increase of humidity is noted in this period which caused moistening of soils and despite enhanced evaporation and evapotranspiration inhibited the process of lake level drop the following 70 years 11 460 11 390 cal bp were rather dry which caused a distinct lowering of the lake and probably also of groundwater level in this period maximum biological productivity per unit area in the lake is noted the whole sequence of phases of rather different climates was completed within a time interval 160 years spanning two human lifes only one should stress that the transitions between the consecutive phases were rather abrupt lasting no longer than 10 years

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

biotic turnover in benthic foraminifera across the cretaceous tertiary boundary at el kef tunisia abstract the cretaceous tertiary boundary section exposed near el kef tunisia is the most complete boundary sequence known to date it contains nearly 1 m of black and gray boundary clay containing planktic foraminiferal zone poa b 2 m of clayey shales of p1a globigerina eugubina zone and 4 m of shales and marls of p1b g taurica zone quantitative analysis of the benthic foraminiferal fauna suggests that deposition during the latest cretaceous occurred in an upper slope to outer shelf environment which shallowed at the k t boundary to an outer to middle shelf depth and shallowed further by p1b time to mid shelf depth a major reduction in benthic diversity occurred near the k t boundary with about 50 of the fauna disappearing diversity remained an average of 37 lower during deposition of the first 3 m of sediment above the boundary poa b p1a and productivity was very low surviving and thriving foraminifers during this interval were primarily low oxygen tolerant epifaunal and infaunal species a sharp decrease in the low oxygen tolerant fauna and appearance of a shallow mid shelf fauna at about 4 m above the boundary p1b zone signals a second regression return to higher oxygen levels and higher productivity although the environmental effects of the k t boundary event can be inferred from benthic faunas the ultimate cause remains elusive faunal changes prior to and the long recovery period after the k t boundary are difficult to explain by a single impact hypothesis