dinoflagellate cyst assemblages as tracers of sea surface conditions in the northern north atlantic arctic and sub arctic seas the new n 677 data base and its application for quantitative palaeoceanographic reconstruction the distribution of dinoflagellate cyst dinocyst assemblages in surface sediment samples from 677 sites of the northern north atlantic arctic and sub arctic seas is discussed with emphasis on the relationships with sea surface parameters including sea ice cover salinity and temperature of the coldest and warmest months difficulties in developing a circum arctic data base include the morphological variation within taxa e g operculodinium centrocarpum islandinium cezare and polykrikos sp which probably relate to phenotypic adaptations to cold and or low salinity environments sparse hydrographical data together with large interannual variations of temperature and salinity in surface waters of arctic seas constitute additional limitations nevertheless the use of the best analogue technique with this new dinocyst data base including 677 samples permits quantitative reconstruction of sea surface conditions at the scale of the northern north atlantic and the arctic domain the error of prediction calculated from modern assemblages is 1 3 ca nd 1 8 c for the temperature of february and august respectively 1 8 for the salinity and 1 5 months yr 1 for the sea ice cover application to late quaternary sequences from the western and eastern subpolar north atlantic labrador sea and barents sea provide reconstructions compatible with those obtained using the previous dinocyst data base n 371 which mainly included modern data from the northern north atlantic copyright 2001 john wiley sons ltd journal of quaternary science

calcite dissolution in sediments of the ceara rise in situ measurements of porewater o2 ph and co2 aq in situ electrode measurements of porewater oxygen and ph from four sites on the ceara rise in the western tropical atlantic unequivocally demonstrate that calcite dissolution driven by metabolic co2 produced within the sediments is a significant part of the diagenesis of sedimentary calcite dissolving at least 20 of the calcite rain to the seafloor the first ever in situ absorbance based measurements of porewater co2 aq support the dissolution estimates based on models of the observed ph distributions and are incompatible with scenarios excluding metabolic co2 driven dissolution our dissolution estimates are consistent with those estimated by an independent study of porewater calcium and alkalinity profiles martin and sayles 1996 at this location the consistency of these disparate porewater measurements and our ability to interpret them with simple models of respiration and dissolution implies that no special mechanism is required to describe this process the calcite dissolution rate constant in the sediments of the deepest station in this study is significantly higher than determined by in situ studies at other locations values approach those determined by early laboratory measurements the dissolution rate constant here must be at least two orders of magnitude higher than for calcite in sediments on the ontong java plateau based on in situ electrode measurements there hales and emerson 1996 the calcite solubility consistent with these data is not compatible with that consistent with the ontong java data the reason for this difference is currently unresolved but may be due to the high order of the empirical dissolution rate law assumed in this study

land sea correlation by means of terrestrial and marine palynomorphs from the equatorial east atlantic phasing of se trade winds and the oceanic productivity abstract sporomorphs and dinoflagellate cysts from site gik16867 in the northern angola basin record the vegetation history of the west african forest during the last 700 ka in relation to changes in salinity and productivity of the eastern gulf of guinea during most cool and cold periods the afromontane forest rather than the open grass rich dry forest expanded to lower altitudes partly replacing the lowland rain forest of the borderlands east of the gulf of guinea except in stage 3 when oceanic productivity was high during a period of decreased atmospheric circulation high oceanic productivity is correlated to strong winds the response of marine productivity in the course of a climatic cycle however is earlier than that of wind vigour and makes wind stress induced oceanic upwelling in the area less likely monsoon variation is well illustrated by the pollen record of increased lowland rain forest that is paired to the dinoflagellate cyst record of decreased salinity forced by increased precipitation and run off

early oligocene dinoflagellate cysts from the upper rhine graben sw germany paleoenvironmental and paleoclimatic implications using principal component analysis and cyst diversity and equity trends we can recognize four distinct dinoflagellate cyst dinocyst assemblages from four rupelian early oligocene cores in the mainz embayment of the northern rhine graben sw germany these assemblages are the spiniferites ramosus pc1 thalassiphora pelagica pc2 homotryblium tenuispinosum pc3 and vozzhennikovia spinula pc4 assemblages the four cores provide an onshore offshore transect in the mainz embayment the h tenuispinosum assemblage shows high factor loadings in proximal to intermediate cores which is interpreted to reflect temporary high salinity conditions mean dinocyst diversity and equity increase with distance from the mid rupelian shoreline indicating increasingly stable paleoenvironmental conditions towards the center of the mainz embayment within individual cores changes in dinocyst assemblages through time are related to paleoenvironmental and paleoclimatological changes the three proximal to intermediate cores show dominance of the h tenuispinosum assemblage repeatedly alternating with high factor loadings of the t pelagica assemblage in both cases dinocyst diversity and equity tend to be reduced highest factor loadings of the s ramosus assemblage occur in intervals where neither of the above assemblages is dominant and tend to coincide with dinocyst diversity and equity maxima we interpret this distribution pattern to denote different paleoceanographic conditions reflecting drier and more humid phases in the early oligocene of central europe during relatively dry periods increased salinity conditions prevailed in proximal to intermediate settings of the mainz embayment as reflected by the dominance of the h tenuispinosum assemblage during more humid periods increased runoff led to higher nutrient availability and the formation of a pycnocline separating slightly less saline surface waters from higher saline deeper waters thus impeding vertical circulation these environmental conditions are documented in high loadings of the t pelagica assemblage which is indicative of increased eutrophication and or oxygen depleted bottom waters transitions between drier and more humid periods i e episodes of normal marine conditions are characterized by high loadings predominantly of the s ramosus assemblage as well as increased dinocyst diversity and equity values we propose that the alternations between drier and more humid phases may be related to variations in the ocean atmosphere moisture flux from the north atlantic into central europe bearing a high latitude climate signal 2002 elsevier science b v all rights reserved

late quaternary protoperidinium cysts as indicators of paleoproductivity in the northern arabian sea the reliability of organic walled cysts of the heterotrophic dinoflagellate protoperidinium as paleoproductivity indicators and the influence of bottom water oxygenation on cyst preservation is assessed by using arabian sea records of the past 125 kyr as a natural laboratory multidisciplinary geochemical micropaleontological and palynological datasets are integrated to analyze the relationship between protoperidinium cyst concentrations and other paleoproductivity proxies differential preservation potential is quantified in order to establish threshold oxidative degradation values for a possible application of quantitative protoperidinium cyst records in paleoenvironmental reconstructions results indicate that variations in protoperidinium cyst concentration closely correspond to other marine productivity and or upwelling proxies although oxygenation will lead to significant cyst degradation and thus decreased concentrations down core patterns in protoperidinium cyst concentration still primarily reflect changes in sea surface productivity in view of differential preservation among dinoflagellate cysts down core variations in relative abundance of protoperidinium should be treated with caution

enhancing bonebed mapping with gis technology using the danek bonebed upper cretaceous horseshoe canyon formation edmonton alberta canada as a case study the danek bonebed is a monodominant edmontosaurus bonebed preserving predominantly disarticulated material from the upper campanian horseshoe canyon formation within the city limits of edmonton al

synchronous basin wide formation and redox controlled preservation of a mediterranean sapropel organic rich sedimentary units called sapropels have formed repeatedly in the eastern mediterranean sea in response to variations of solar radiation sapropel formation is due to a change either in the flux of organic matter to the sea floor from productivity changes or in preservation by bottom water oxygen levels however the relative importance of surface ocean productivity versus deep water preservation for the formation of these organic rich shale beds is still being debated and conflicting interpretations are often invoked1 2 3 4 5 6 7 here we analyse at high resolution the differences in the composition of the most recent sapropel s1 in a suite of cores covering the entire eastern mediterranean basin we demonstrate that during the 4 000 years of sapropel formation surface water salinity was reduced and the deep eastern mediterranean sea below 1 800 m depth was devoid of oxygen this resulted in the preferential basin wide preservation of sapropel s1 with different characteristics above and below 1 800 m depth as a result of different redox conditions we conclude that climate induced stratification of the ocean may therefore contribute to enhanced preservation of organic matter in sapropels and potentially also in black shales

the erosional response of calcareous soils along a climatological gradient in southeast spain abstract the erosional response of calcareous soils along a climatological gradient in alicante se spain was studied the erosional response was defined in terms of indicators obtained from field rainfall simulation experiments and laboratory studies of soil aggregation measurements were made at seven sites on limestones and marls between benidorm with an annual average rainfall of 400 mm yr 1 and coll de rates annual rainfall 900 mm yr 1 the sites were on matorral vegetation affected to varying intensities by grazing and fire at the seven locations soil aggregation was studied by sieving by the single water drop test and by a microscan particle sizer rainfall simulation experiments were made on circular 55 cm diameter target area plots using the calvo simulator at an intensities between 35 and 59 mm h 1 on limestone it was found that on bare surfaces the coarse soil aggregation increases with depth at the highest sites and decreases at the lower sites the benidorm surface soil has the highest erodibility the least stable soils are at the lower intermediate sites on marls the aggregate stability is generally high in contrast to those under cultivation simulated runoff from the wetter limestone sites is very low the driest areas have the highest runoff and sediment yields trends with climate suggest that the erosional responses of the soils indeed increase with aridity and temperature but local factors have a large effect particularly at intermediate altitudes a clear relationship like that found in israel by lavee on a similar lithology does not exist

deposition of sapropel s1 sediments in oxic pelagic and anoxic brine environments in the eastern mediterranean differences in diagenesis and preservation sediments from a boxcore in the previously anoxic brine filled poseidon basin eastern mediterranean have been studied and compared to sediments deposited in a normal eastern mediterranean environment the boxcore can be divided into three main sedimentary intervals based on ams radiocarbon ages foraminiferal and geochemical zonations from the base of the core upwards these are 1 12 3 31 2 cm organic rich sediments redeposited from within the brine 2 6 6 12 3 cm sediment containing a cold foraminifera fauna redeposited from above the brine into the basin while the brine was still present 3 0 6 6 cm oxic pelagic sediment accumulated since the reoxygenation of poseidon basin which occurred1800 yrs bp near the base of the latter unit a mn oxide peak has formed and it marks the present boundary between oxic and suboxic environments a progressive downward oxidation front which is usually found in normal sapropel s1 sediments has never formed in poseidon basin sediments this has resulted in the preservation of the relationship between organic carbon and organic related trace elements e g se in the organic rich sediments of poseidon basin whereas such a relationship has been obliterated in normal sapropel s1 sediments on the basis of the carbonate content as well as the sr ca ratio preservation of carbonates appears to be better in the brine sapropel sediments of bc15 than it is in normal sapropel s1 sediments the high opal content of bc15 shows that biogenic opal is also much better preserved the overall lower corg ba ratio in bc15 suggests a better preservation of barite relative to that of organic carbon in shallow brine sediments but is as yet inconclusive for the organic carbon preservation potential of brine relative to normal unoxidised sediments 1999 elsevier science b v all rights reserved

dinoflagellate cysts from sediment traps deployed in the bellingshausen weddell and scotia seas antarctica dinoflagellate cysts have been recovered from six long term 1 2 yr sediment trap moorings deployed in the bellingshausen weddell and scotia seas antarctica these traps mostly moored near the sea bed to sample the nepheloid layer were located both within and to the north of the maximum sea ice limit the numbers of cysts together with the composition of the assemblages reinforce the importance of the maximum sea ice limit as a modern biogeographic boundary for the distribution of dinoflagellate cysts cysts derived from heterotrophic dinoflagellates make up the highest proportions within the assemblages recovered from the traps one trap sampled the export production revealing little difference in cyst flux over those sampling the nepheloid layer cyst flux appears to be highest in areas closest to the antarctic convergence north of the maximum sea ice limit and to high nutrient availability there are however differences between the sediment trap assemblages and those recovered from core top samples at the same or nearby sites these differences in the greater number of cysts and in the higher numbers of round brown protoperidinium cysts in the traps may reflect annual differences in the primary productivity and or cyst production in the area in some areas the sediment record may preserve little information about local surface water productivity because of the activity of bottom water currents for example those arising from the antarctic circumpolar current

late quaternary upwelling variations in the eastern equatorial atlantic ocean as inferred from dinoflagellate cysts planktonic foraminifera and organic carbon content abstract analysis of multiple proxies shows that eastern equatorial atlantic upwelling was subdued during isotope stage 5 5 more intense during stages 4 5 2 5 4 and 6 and most intense early in stage 2 these findings are based on proxy measures from a core site about 600 km southwest of liberia the proxies include total organic carbon content the ratio of peridinoid and oceanic organic walled dinoflagellate cyst species accumulation rates of calcareous dinoflagellates estimates of sea surface paleotemperatures the difference in stable oxygen isotope composition between two species of planktonic foraminifera that live at different water depths and the abundance of the planktonic foraminifera neogloboquadrina dutertrei most of these parameters consistently vary directly or inversely with one another slight discrepancies between the individual parameters show the usefulness of a multiple proxy approach to reconstruct paleoenvironments our data confirm that northern summer insolation strongly influences upwelling in the eastern equatorial atlantic ocean

integrating palynological and geochemical data in a new approach to palaeoecological studies upper cretaceous of the banterwick barn chalk borehole berkshire uk abstract the dinoflagellate cyst record from an upper cretaceous uppermost cenomanian upper coniacian chalk core drilled at banterwick barn berkshire is described and statistically correlated with elemental and stable isotope bulk sediment geochemical data from the same core seventy two dinocyst species and subspecies are recorded and stable carbon and oxygen isotopic 13 c 18 o trends are documented lithostratigraphy and chemostratigraphic correlation of the 13 c curve with an expanded section at dover kent are used to identify stratigraphically significant marls and determine the positions of macrofossil zones and stage boundaries in the banterwick barn core these data indicate that 30 m of chalk at dover are represented by senoniasphaera rotundata alveolata is proposed which has a fad in the lower turonian and last appears lad in the lower coniacian senoniasphaera rotundata rotundata autonym herein has its fad in the middle turonian first common occurrence in the uppermost turonian and lad in the upper coniacian an extremely impoverished assemblage of dinocysts in the highest cenomanian to lowest turonian is considered to be largely a preservational artefact of intraclastic nodular and calcarenitic chalks and is not related directly to the well documented global oceanic anoxic event oae2 occurring at that time 93 5 ma a sharp increase in dinocyst abundance in the lower turonian corresponds with a change in lithology to more marly chalks a gradual decrease in the number of species is observed through the middle turonian to upper coniacian 18 o records show that this was associated with global climatic cooling cluster analysis of the dinocyst abundance record with geochemical data indicates four distinct species groups with characteristic geochemical associations i e groups 1 4 groups 1 and 2 are associated with phases of increased siliciclastic supply a positive correlation with higher 13 c values differentiates the latter group 3 is independent of carbonate and detrital input and group 4 is associated with high carbonate flux and low detrital supply these groupings suggest that cyst forming dinoflagellates exhibited a range of ecological niches in the late cretaceous although the relationship between the encystment process and the geochemical associations is unclear key environmental factors are likely to be sea level and climate related including water depth turbidity nutrient supply sea surface temperature and environmental stability predictability integrated geochemical and palynological studies have great potential for inter regional correlation and palaeoenvironmental interpretation

towards quantitative environmental reconstructions from ancient non analogue microfossil assemblages ecological preferences of paleocene eocene dinoflagellates abstract we explore a novel approach towards quantification of paleo ecological signals from non analogue microfossil assemblages by quantifying relations between assemblages and high quality geochemical and sedimentological data from sedimentary archives we test this approach using one group of microfossils the organic cysts of dinoflagellates dinocysts which are widely used in shelf and open marine settings for biostratigraphy and reconstructions of past environments and environmental change similar to other microfossil groups dinocysts can be used to reconstruct environments with relatively high confidence for recent time periods as species affinities can be derived from observational and instrumental data in the absence of such data the ecology of extinct species is much less certain and as a result reconstructions in deep time are often limited to qualitative interpretations to explore if quantitative empirical relations between extinct dinocysts and high quality geochemical data can be established we study a major event of climate change the paleocene eocene thermal maximum petm 56 ma ago the petm is a particularly suitable period for this exercise as there is a multitude of large environmental perturbations associated with the transient global warming such as deoxygenation sea level rise and an accelerated hydrological cycle the synthesized published dataset exhibits better spatial and temporal coverage compared to any other period in deep time we extract empirical relations for the abundance of previously proposed paleoecological groups as a function of independent environmental proxies for example sea surface temperature and terrestrial organic matter input the results unequivocally illustrate that many dinocysts show relations to several of the reconstructed environmental variables notably we show that one genus apectodinium and an ecogroup epicystal goniodomidae required sea surface temperatures in excess of 20 c and 25 c respectively while one species florentinia reichartii was only abundant between 30 and 35 c other groups apparently favored either a limited spiniferites or high senegalinium terrestrial input to the study site relating to salinity nutrient levels or suspended sediment load i e murkiness crucially our work shows that the validation and quantification of ecological signals by independent environmental proxy data provides the opportunity to extract more quantitative information from a wide range of non analogue microfossil assemblages while this approach is not limited to any specific group of microfossils or macrofossils we stress that proper calibration datasets high quality sedimentological and geochemical proxy records are needed and should ideally have decent geographical coverage and include one or more environmental perturbations using this approach such empirical relations can be established for a wide range of microfossil groups that have highly complementary geological records which increases the value of existing data and ensures future application of microfossil based paleoecology

a multi proxy study of pliocene sediments from ile de france north east greenland abstract a multi technique approach has been used to study a pliocene shallow water marine deposit designated the ile de france formation in north east greenland the sequence is correlated on the basis of 87sr 86sr ratios in shells and palaeomagnetic studies with the gauss normal polarity chron which is dated to between 2 60 and 3 58 ma years bp this dating is in accordance with amino acid epimerisation and evidence from dinoflagellates foraminifers and molluscs sediments marine molluscs and foraminifers show that the sequence was deposited on the inner shelf below storm wave base seawater temperatures were much higher than today as demonstrated by the occurrence of a number of southern extra limital species the same applies to air temperature and the few remains of land plants may indicate a forested upland with picea and thuja a number of extinct taxa are present including nucula jensenii that is erected as a new species

middle and late quaternary depositional sequences and cycles in the eastern mediterranean although most of the quaternary sediments of the eastern mediterranean appear reworked extensive areas of hemipelagic sediments occur mainly in the central part of the basin mediterranean ridge the most obvious character of these muddy sediments is the numerous changes in colour they result from the organic carbon content as well as from concentration and chemical form of metallic elements mn fe cu zn the succession of coloured layers is arranged into sequences developed between two sharp contacts a complete sequence involves five lithofacies from an oxidized layer at the base to a reduced sapropel at the top and displays progressive internal changes of colour from ochre beige greyish beige grey and black layers several sequence variants top truncated base truncated recurrent are identified these sequences are a consequence of changes in oceanographic conditions i e from oxidizing to reduced environments resulting in different organic and mineral contents based on detailed studies of quaternary sediments collected by coring a synthesized standard succession representative of the ordered sequences in the eastern mediterranean is proposed from about 650 000 yr as deduced from the calculated rate of sedimentation of 1 7 mm 1000yr 1 this succession appears modulated by cyclic events large scale periods 200 000 yr of reduced and oxidized sequences correlate with major alternate phases of flooding and reduced flow of the nile river during the quaternary subsequent sequences of shorter time scale 20 000 50 000 yr results from two factors heaviest monsoons leading to an increase of the influx of the nile river and global climatic changes eurasian ice sheet meltwater these two factors act synchronously or independently along the studied time span these interplaying factors result in periodic stages of increasingly restricted conditions in the basin and explain the complexity of the eastern mediterranean succession at least since 650 000 yr ago

a centennial scale organic walled dinoflagellate cyst record of the last deglaciation in the south adriatic sea central mediterranean abstract a high resolution study of sea surface temperature sst and primary productivity changes during the last deglaciation in the south adriatic sea is presented on the basis of organic walled dinoflagellate cysts dinocysts compared with stable oxygen and carbon isotope records derived from globigerina bulloides two more defined warming phases between 14 75 and 14 10 cal kyr bp gi 1e and between 13 85 and 13 25 cal kyr bp gi 1c and perhaps a mild one between 12 95 and 12 60 cal kyr bp gi 1a interrupted by two cold events between 14 10 and 13 85 cal kyr bp gi 1d and between 13 25 and 12 95 cal kyr bp gi 1b are highlighted weaker sst oscillations occurred within the relatively stable periods gs 2a 17 00 14 75 cal kyr bp gs 1 or younger dryas 12 60 11 60 cal kyr bp and early holocene several dinocyst proxies used to evaluate surface primary productivity suggest that the cold events gi 1d and gi 1b are associated with episodes of both enhanced primary productivity and perhaps improved organic matter preservation due to reduced deep water formation phases of more pronounced increased surface primary productivity without stagnation in bottom waters are recorded during gi 1c and early gs 1 freshwater po river discharge seems to be the cause of enhanced productivity during event gi 1c at 13 4 cal kyr bp and probably during gi 1d

river inflow and salinity changes in the caspian sea during the last 5500 years abstract pollen spores and dinoflagellate cysts have been analysed on three sediment cores 1 8 1 4 m long taken from the south and middle basins of the caspian sea a chronology available for one of the cores is based on calibrated radiocarbon dates ca 5 5 0 8 cal ka bp the pollen and spores assemblages indicate fluctuations between steppe and desert in addition there are some outstanding zones with a bias introduced by strong river inflow the dinocyst assemblages change between slightly brackish abundance of pyxidinopsis psilata and spiniferites cruciformis and more brackish dominance of impagidinium caspienense conditions during the second part of the holocene important flow modifications of the uzboy river and the volga river as well as salinity changes of the caspian sea causing sea level fluctuations have been reconstructed a major change is suggested at ca 4 cal ka bp with the end of a high level phase in the south basin amongst other hypotheses this could be caused by the end of a late and abundant flow of the uzboy river now defunct carrying to the caspian sea either meltwater from higher latitudes or water from the amu daria a similar later clear phase of water inflow has also been observed from 2 1 to 1 7 cal ka bp in the south basin and probably also in the north of the middle basin

alternative origin of aliphatic polymer in kerogen the origin of sedimentary organic matter kerogen has been attributed to random recombination reactions of biological components in sediments or to selective preservation of decay resistant macromolecules neither hypothesis explains the aliphatic composition of the cuticle of fossil arthropods thermal maturation experiments on modern arthropods involving confined pyrolysis at 250 360 c degrade the chitin protein complex of the cuticle and transform free aliphatic components into a polymeric structure the results of the application of electron microscopy and spectroscopic methods to modern thermally matured and fossil arthropod cuticles indicate that in situ polymerization of free and ester bound cuticular lipids can lead to kerogen formation thus fossil arthropod fragments can contribute to sedimentary organic matter

variability of sea ice cover in the chukchi sea western arctic ocean during the holocene 1 dinocysts from cores collected in the chukchi sea from the shelf edge to the lower slope were used to reconstruct changes in sea surface conditions and sea ice cover using modern analogue techniques holocene sequences have been recovered in a down slope core b15 2135 m 75 44 n sedimentation rate of 1 cm kyr 1 and in a shelf core p1 201 m 73 41 n sedimentation rate of 22 cm kyr 1 the shelf record spanning about 8000 years suggests high frequency centennial oscillations of sea surface conditions and a significant reduction of the sea ice at circa 6000 and 2500 calendar cal years b p the condensed offshore record b15 reveals an early postglacial optimum with minimum sea ice cover prior to 12 000 cal years b p which corresponds to a terrestrial climate optimum in bering sea area dinocyst data indicate extensive sea ice cover 10 months yr 1 from 12 000 to 6000 cal years b p followed by a general trend of decreasing sea ice and increasing sea surface salinity conditions superimposed on large amplitude millennial scale oscillations in contrast 18o data in mesopelagic foraminifers neogloboquadrina pachyderma and benthic foraminifers cibicides wuellerstorfi reveal maximum subsurface temperature and thus maximum inflow of the north atlantic water around 8000 cal years b p followed by a trend toward cooling of the subsurface to bottom water masses sea surface to subsurface conditions estimated from dinocysts and 18o data in foraminifers thus suggest a decoupling between the surface water layer and the intermediate north atlantic water mass with the existence of a sharp halocline and a reverse thermocline especially before 6000 years b p the overall data and sea ice reconstructions from core b15 are consistent with strong sea ice convergence in the western arctic during the early holocene as suggested on the basis of climate model experiments including sea ice dynamics matching a higher inflow rate of north atlantic water

dinoflagellate cyst distribution in surface sediments along the south western mexican coast 14 76 n to 24 75 n abstract in this study we explore the relationship between the modern assemblages of organic walled dinoflagellate cysts and sea surface conditions temperature salinity primary productivity and water depth and distance to the coast statistical treatments were performed on 95 surface sediment samples from sites located along the south western mexican coast 14 76 n to 24 75 n redundancy analysis rda illustrates that the principal parameters correlated with the regional cyst distribution are the distance to the coast and the productivity in the upper water column which is closely related to upwelling intensity empirical observations coupled with rda provide insight into the spatial coverage of some cyst taxa produced by dinoflagellate species potentially responsible for harmful algal blooms along the coast they also allow the recognition of four zones of assemblages which are linked to the upwelling intensity and the productivity and characterize la paz bay the south western mexican margin from 15 95 n to 23 11 n the northern part of the gulf of tehuantepec and the southern part of the gulf of tehuantepec

the influence of organic matter diagenesis on caco3 dissolution at the deep sea floor abstract in situ benthic flux chamber measurements were performed at seafloor locations in the atlantic and pacific oceans where the bottomwaters were supersaturated approximately saturated and undersaturated with respect to calcite there was no evidence of significant dissolution at or above the saturation horizon below the saturation horizon however significant benthic fluxes of titration alkalinity and calcium out of the sediments were observed indicating appreciable dissolution where observed the rate of dissolution is consistent with a rate expression of reaction order 4 5 and a rate constant in the range of 0 05 to 0 5 per day a numerical simulation was constructed to represent organic matter and caco3 diagenesis at the seafloor at the supersaturated and near saturation sites the model over predicts the influence of metabolically produced co2 on the extent of caco3 dissolution it is possible that these results can be reconciled by a better understanding and parameterization of organic matter mineralization and porewater transport processes in surface sediments the primary factors to be considered include 1 the oxidation state of the carbon being oxidized 2 the vertical distribution of oxidation rates including the role of doc in sediment remineralization 3 the influence of nondiffusive transport of near surface porewaters and 4 the influence of episodic depositional events on organic and inorganic carbon cycling

paleo oxygenation in tertiary epeiric seas evidence from dinoflagellate cysts the dinoflagellate cyst record from an epeiric setting in the oligocene of southwest germany exhibits major changes associated with variations in paleo oxygenation inferred from benthic foraminifera dinoflagellate cyst diversity and equitability strongly decline in the case of extreme oxygen depletion the relative abundance of the dinoflagellate cyst thalassiphora pelagica inversely correlates with the availability of benthic oxygen the t pelagica spectrum consists of different morphotypes which are considered to represent different stages within the cystal part of the t pelagica life cycle following the concept of benedek and gocht the distribution of these morphotypes is also linked to oxygen availability horizons with highest t pelagica abundances are characterized by the occurrence of t pelagica specimens representing an early stage in cyst formation a model is proposed that uses t pelagica as a proxy to assess oxygenation both at the sediment surface and in the water column the occurrence of t pelagica specimens representing an early stage in cyst formation is interpreted to reflect the extension of oxygen depletion upwards into the water column because t pelagica is an easily recognized globally distributed element of paleogene and early neogene dinoflagellate cyst assemblages the application of this model may be of importance in the reconstruction of paleo oxygenation in epeiric settings from these times its sensitivity to changes in benthic oxygenation can be as high as if not higher than that of the approach based on foraminifera moreover it is applicable to decalcified sediments

molecular and isotopic composition of foraminiferal organic linings abstract fossil remnants of benthic foraminifera consist of carbonate tests and their organic linings the macromolecular and stable isotopic composition of these benthic foraminiferal organic linings was characterized to evaluate their potential use as paleoclimate proxies using curie point pyrolysis gc ms py gc ms we show that benthic foraminiferal organic linings consist of protein and polysaccharides bound together in a complex macromolecular structure both chitin derivatives and traces of guaiacols and syringols usually assigned to lignin are found although the five species of benthic foraminifera all contain chitin derivatives and proteins the relative contribution of these compounds tends to vary considerably oxygen stable isotopic analyses of the organic linings of the benthic foraminiferal species ammonia tepida indicates that 18 o ol values are in line with fractionation between seawater and organic matter in contrast a 13 c deliberate tracer experiment showed that metabolic carbon is the main source for the carbon fixed in the organic lining the different pathways of carbon and oxygen stable isotopes into the foraminiferal linings have important implications for future proxy development as they reflect different components of the environment compared to the carbonate bound stable isotopes still the future application of benthic foraminiferal organic linings and their isotopic values critically relies on improvements in calibration and sample size required for isotopic analyses

dinoflagellate cysts paleoproductivity and upwelling systems a late cretaceous example from israel abstract diverse assemblages of dinoflagellate cysts occur in coniacian maastrichtian sedimentary sequences in israel which represent the inner shallower and outer deeper seaward belt of a late cretaceous upwelling system along the margin of the southern tethys the assemblages are composed mainly of peridinioid p and gonyaulacoid g cysts in varying concentrations it is suggested that the observed fluctuations in the numerical peridinioid gonyaulacoid p g cyst ratio reflect mainly changes in upwelling intensity and productivity in the studied area high p g values represent a higher productivity and vice versa thep g curve indicates a generally high productivity during the campanian followed by a decrease during the maastrichtian the inner part of the upwelling region is characterized by higherp g values representing a higher productivity the similarity between thep g ratio curve and the foraminiferal based paleoproductivity curve from the same sections supports the utility of thep g ratio as a reliable productivity indicator applied here for the first time to upper cretaceous sediments

late holocene oceanic variability in the southern benguela region driven by interplay of upwelling fluvial discharge and agulhas leakage the southern benguela upwelling system near the st helena bay has been proposed to be affected by various factors while few investigations about the late holocene oceanic conditions has been carr

the erodibility of highly calcareous soil material from southern spain abstract the erodibility of highly calcareous and gypsiferous soils from three locations in southern spain is examined the reasons for the poor structural condition of the soils are reviewed and attention given to the problem of obtaining good analytical data for highly calcareous materials the most erodible soils are from areas of badlands where sodium salts are present in the parent material these and all of the soils except those containing pedogenic oxides for example free iron or high amounts of organic material are subject to slaking and have low rates of water acceptance the aggregate stability as measured by an ultrasonic dispersion procedure and by the water drop test is relatively low for all materials except those containing high amounts of organic matter the size distibution of the breakdown products of the aggregates obtained by different procedures is considered

a gis based approach to documenting large canid damage to bones abstract experimental studies of modern carnivore tooth marking patterns are integral to understanding the nature of carnivore involvement in archeological bone assemblages however modern bone damage data for most carnivore taxa are limited this is particularly true for canids this study presents bone damage data collected from feeding experiments conducted with mexican gray wolves canis lupus baileyi and red wolves canis rufus this is the largest experimental assemblage reported for canids to date the image analysis gis approach described by marean et al 2001 is expanded on here and used to document bone preservation and tooth mark distribution for the first time in a carnivore modified bone assemblage further we introduce the use of the arcgis spatial analyst to identify significant concentrations of bone modifications results show that the distribution of tooth pits varies considerably across elements as well as across different portions of the same element and that significant clusters of tooth pits occur on all long bones we suggest that with a large enough sample the gis spatial analyst can be a useful tool for analyzing the distribution of bone modifications with greater resolution than previous methods this method facilitates comparisons between experimental and fossil assemblages which may aid in identifying the timing of access to carcasses by carnivores involved in modifying fossil assemblages finally the use of this rigorous methodology is a step toward increasing standardization in methods of taphonomic analysis

modification and complete removal of eastern mediterranean sapropels by postdepositional oxidation sapropels unusually dark organic rich sediment layers whose origin is controversial are widespread in the eastern mediterranean the upper surfaces of these layers appear sharp and show little evidence of bioturbation it has been suggested that postdepositional oxidation may have removed the dark coloration from the upper part of the original layer so that the top of the visible layer now lies somewhat below the original position of the sapropel top such a diagenetic alteration has considerable implications for the interpretation of the sedimentary record where the tops of dark layers are usually correlated with the cessation of sapropel formation geochemical data demonstrate that all visual evidence of a thin example of the most recent eastern mediterranean sapropel has been removed from the sedimentary record by oxidation processes such a process may have thinned all sapropel units by several centimetres the most recent period of sapropel formation probably ended as recently as 5 ka cf cited values between 6 0 and 7 6 ka

late holocene paleoenvironmental history of bioluminescent laguna grande puerto rico abstract coastal lagoons are valuable natural resources and ecotourism hotspots that are at great risk due to human development and global climate change in order to protect these resources it is important that we fully understand the paleoenvironmental history of these unique ecosystems and their sensitivity to environmental change here we present a multi proxy pollen charcoal grain size dinoflagellate cyst stable isotope geochemistry and foraminifera 3600 cal yr b p record of paleoenvironmental change for laguna grande puerto rico which is a particularly unique coastal lagoon as it contains high abundances of the bioluminescent dinoflagellate pyrodinium bahamense sedimentary evidence indicates that the laguna grande basin began accumulating sediment 3600 cal yr b p coincident with regional sea level rise but the modern lagoon itself is geologically quite young and did not become fully enclosed until 575 cal yr b p due to longshore depositional processes and mangrove swamp development foraminifera assemblages suggest a potential breach of a protective barrier 1550 cal yr b p perhaps as a result of a tropical storm or tsunami and is coincident with an increase in fire activity only two high energy depositional units tempestites could be identified in the lagoon sediments over the last 575 cal yr b p indicating minimal impact by tropical storms or tsunamis on the lagoon since isolation from the open ocean fossil dinoflagellate cyst concentrations and influxes do not approach modern levels until 200 cal yr b p and are currently at the highest levels in the history of the lagoon indicating the lagoon may have become bioluminescent only recently perhaps as a result of anthropogenic nutrient additions sedimentation rates support this hypothesis indicating a recent tripling of sedimentation rates when compared to millennial scale sedimentation rates this study highlights the utility of paleolimnological data in the management and preservation of at risk coastal lagoon ecosystems

macromolecular composition of the dinoflagellate cyst thalassiphora pelagica oligocene sw germany origin composition and fate of organic particles in marine sediments are to a large extent unknown here we contribute to resolving this lack of information by reporting on the structural characterization ftir micro spectroscopy py gc ms and tmah assisted thermochemolysis gc ms of hand picked thalassiphora pelagica dinoflagellate cysts oligocene the cyst wall macromolecule is relatively condensed it is composed of a mixture of aliphatic moieties with the linear carbon units having an average chain length of 12 carbon atoms in the pyrolysate this is reflected in aliphatic series of alkanes and alkenes both c23 alkan 2 ones c16 and alkylbenzenes c20 and a high abundance of alkylated indenes and naphthalenes both c13 the relatively strong aromatic signature of the pyrolysate supports a relatively extensive cross linking between the aliphatic moieties which is very unlike the highly aliphatic resistant biopolymer walls of chlorophyta and eustigmatophyta but agrees with the sparse information on organic walled cysts of other dinophyta thermochemolysis further supports the above and further indicates that carboxylic acids have been added to the macromolecule post mortem additional series of alkylated thiophenes and benzothiophenes present in the pyrolysate and thermochemolysate are considered to result from early sulphurisation of the cysts in the anoxic to suboxic setting of the depositional environment

palaeoproductivity and post depositional aerobic organic matter decay reflected by dinoflagellate cyst assemblages of the eastern mediterranean s1 sapropel abstract in the reconstruction of bioproductivity in surface waters the extent to which a proxy has been diagenetically altered is often a matter of debate here we investigate how organic and calcareous walled dinoflagellate cysts can be used for separately estimating bioproductivity and oxygen related diagenesis this is achieved by studying the cyst content of the most recent eastern mediterranean sapropel s1 that is thought to have been deposited under conditions of increased primary production in surface waters and possible anoxia in the bottom waters based on chemical evidence it has been shown that the visible sapropelic layer represents only the residual lower part of what was initially a much thicker sapropel as a result of post depositional decay of organic matter related to oxygen penetration into the sediments the effect of aerobic organic matter decay on the cyst associations is studied through the comparison of the unaffected lower part of the initial sapropel and the oxidised upper part comparing the unaffected sapropelic sediments with pre and post sapropelic material gives insight into the relationship between fossil cysts assemblages and palaeoproductivity impagidinium aculeatum impagidinium patulum operculodinium israelianum polysphaeridium zoharyi and probably impagidinium spp impagidinium paradoxum and nematosphaeropsis labyrinthus are very resistant against aerobic decay and their accumulation rates appear to be primarily related to productivity in surface waters protoperidinium and echinidinium species on the other hand are shown to be very sensitive and can be used to recognise oxygen related decay the calcareous walled dinoflagellate cysts seem to be unaffected by oxic organic matter decay in mediterranean sediments

review of recent advances in the interpretation of eastern mediterranean sapropel s1 from geochemical evidence abstract the sediments of the eastern mediterranean basin contain c org enriched layers sapropels interbedded with the c org poor sediments which form by far the greater part of the record while it is generally appreciated that different surface ocean productivity and bottom water conditions are necessary for the formation and preservation of these two sediment types less attention has been paid to diagenetic effects which are an expected consequence of transitions between dramatically different bottom water oxygenation levels a geochemical interpretation has emerged of post depositional oxidation of the most recent sapropel s1 initially based on the relationship of the mn fe c org and s concentration depth profiles observed around s1 and the characteristic shapes of these elemental profiles known from other situations this indicates that post depositional oxidation has removed approximately half of the visual evidence of the sapropel 6 cm from a total of 12 cm in the deep basin the oxidation interpretation from redox sensitive element redistribution profiles has subsequently been consolidated with evidence from pore water o 2 no 3 mn 2 and fe 2 studies from characteristic solid phase ba profiles which yield palaeoproductivity records and from oxidation sensitive indicator trace elements i and se so far these geochemical observations have been concentrated in the deeper central parts of the basin where sediment accumulation rates are lower than on the basin margins and radiocarbon dating indicates that s1 formation occurred between 5 3 and 9 0 ky uncorrected conventional radiocarbon time it remains to be demonstrated whether or not these times are applicable to the entire e mediterranean basin the implications of these findings to guide sampling in future work on the s1 productivity episode and on older sapropels for palaeoenvironmental investigations are discussed

active post depositional oxidation of the most recent sapropel s1 in sediments of the eastern mediterranean sea abstract over a wide area of the eastern mediterranean basin two mn rich layers have been observed above the most recent sapropel s1 one immediately above the sapropel top and one a few centimetres closer to the sediment surface different mechanisms have been proposed to explain the occurrence of these two mn peaks either both peaks have a diagenetic origin in which case the upper mn peak is actively forming or the lower peak is actively forming and the upper peak has a different formation mechanism high resolution porewater including a gel sampler used for the first time in marine sediments and solid phase data are now used to demonstrate that the oxidation front is located at the level of the lower mn peak which therefore is presently being formed a barium organic carbon relationship is used to calculate the initial organic carbon profile of the s1 sapropel the palaeoproductivity profiles generated by this method demonstrate that the original sapropel unit was bounded by the upper mn peak this implies that the interval between the two mn peaks where a low organic carbon content is now observed was originally part of the sapropel the initially deposited organic carbon has been oxidised by a progressive downwards moving oxidation front the penetration depth of this oxidation front i e the distance between the two mn peaks is mainly determined by the organic carbon content the sediment accumulation rate and the bioturbation depth the upper mn peak appears to have formed as a result of either mn precipitation upon oxygenation of previously anoxic eastern mediterranean deep water or preservation of a surficial mn peak at the end of the high productivity episode in either case the upper mn peak marks the end of sapropel formation as indicated by the ba profiles this means that formation of the s1 sapropel ceased more recently than is indicated by radiocarbon dating of the visible top of s1

aggregate stability in range sandy loam soils relationships with runoff and erosion abstract the spatial variability of soil aggregate stability and its relationship to runoff and soil erosion were examined in a catena of soils and vegetation in a semiarid environment at the rambla honda field site tabernas almeria se spain to evaluate the validity of structural stability as a soil erosion indicator in sandy loam range soils the influence of soil properties and topography on the variability of aggregate stability was also examined methods include 1 aggregate stability assessment at 12 sites 3 repetitions per site on the hillslope by two methods a aggregate size distribution by dry sieving b water drop test 2 soil organic carbon content 3 particle size distribution determination 4 terrain attributes derived from a digital elevation model 1 m resolution 5 monitoring runoff and erosion for nearly 3 years in eight 10 2 m plots distributed over the hillslope results 41 of the average soil mass is formed by 2 mm aggregates however wet aggregate stability is poor with a mean of a total of 1440 aggregates of only 26 drop impacts necessary to break up a wet aggregate pf 1 significant relationships were found in the number of water drops required for aggregate breakdown and runoff and erosion rates however no significant relationships between the mean weight diameter of aggregates under dry conditions and runoff or erosion rates were observed the relationships of aggregates with other soil properties hillslope position and proximity to plants are also analysed the most significant correlation found was between the number of drop impacts and soil organic matter content the stability of topsoil aggregates seems to be a valuable indicator of field assessed runoff and inter rill erosion of sandy loam range soils under semiarid conditions

calcareous dinoflagellate cysts in surface sediments from the mediterranean sea distribution patterns and influence of main environmental gradients abstract the distribution of calcareous dinoflagellate cysts in surface sediments from the mediterranean sea was quantitatively analysed the samples contain 11 cyst species and the vegetative coccoid thoracosphaera heimii cyst abundance increases towards the deeper parts of the basins and is generally higher in the eastern mediterranean sea three major distribution characteristics exist 1 different assemblages in oceanic and neritic regions 2 little agreement with the associations of areas studied so far like the atlantic ocean and 3 a unique oceanic assemblage in the eastern mediterranean sea a gradual change in cyst assemblages from the western to the eastern mediterranean sea was observed and statistically compared with the main environmental gradients in the upper water column temperature nitrate concentration and possibly salinity appear to be the most important factors controlling cyst production three groups containing cysts with similar environmental preferences can be distinguished 1 an eastern mediterranean group related to relatively high temperature and salinity but low nitrate concentration 2 a group of more or less consistently abundant cosmopolitan species tolerating or even preferring relatively low temperature and salinity but high nitrate concentration and 3 a group containing species that are possibly adapted to neritic environments and have probably been transported from coastal areas into the studied regions in contrast to other calcareous plankton calcareous dinoflagellate cysts correlate strongly with the main environmental gradients in the mediterranean sea bearing a high potential for palaeoenvironmental reconstructions

indices for the estimation of interrill erodibility of moroccan soils abstract replicated runoff and soil loss measurements were made on nine morrocan soils having 9 to 10 slopes using a rainfall simulator soil physical chemical and mineralogical properties were measured at each site forty two individual soil properties or combinations of properties were related by regression analysis to soil loss variation in erodibility of the major soils studied are explained by the resistance of aggregates to dispersion and interrill transportation the high relative erodibility of the calcareous soils was partly attributed to the occurrence of caco3 in the silt size fraction the smectitic nature of the clay minerals in the vertisols and their low organic matter content are important factors in their low infiltration capacity and higher soil loss rate the slaking process resulted in strong small aggregates that were vulnerable to transport and removal from the soil surface agreement was found between the relative erodibility obtained with the use of the rainfall simulator and the relative magnitude of the erosion problems as observed in the field and reported by other authors in the region a multiple regression model using only three soil variables i e soil 2 mm sand electrical conductivity and silt and clay size so called active caco3 predicted soil loss with an r2 0 980 this regression model used as a relative erodibility index could represent a valuable tool for areas in morocco where limited information is available on soil erosion

the micropaleontological character of anomalous calcareous sediments of late pliocene through early pleistocene age below the ccd in the northwestern north pacific ocean calcium carbonate was preserved more than 1 km below the modern calcite compensation depth ccd at odp site 1179 over several short intervals around 2 5 2 4 1 65 and 0 9 0 7 ma this anomalous preservation resulted from a combination of increased production of planktonic foraminiferal tests at the sea surface and increased rate of sedimentation to the sea floor the abundance of dinoflagellate cysts in calcareous sediments records intense plankton blooms and the preservation of oxidationsusceptible round brown brigantedinium cysts in foraminifer rich samples supports the theory of rapid burial the rise in seasurface productivity was driven by enhanced flux of continentally derived limiting nutrients consistent with the pollen evidence of continental aridification cooling and an increase in wind strength the abundant pollen dominated by steppe herb and montane boreal conifer taxa contrasts with lower pollen concentrations dominated by temperate subtropical deciduous tree and taxodium type pollen in non calcareous sediments d 2004 elsevier b v all rights reserved

aggregate stability of soils in central spain and the role of land management the paper examines the relationships between soil aggregate stability selected soil properties and land use in central spain aggregate stability indices derived from three procedures were found to be significantly p 0 01 correlated with each other as well as with clay content organic carbon and a range of water soluble salts soils with a higher clay content have a lower aggregate stability it appears that the presence of expandable clays has a major negative influence although this impact is strongly modified by recent land use history and contemporary land management practices agricultural land abandoned in the 1940s was subsequently invaded by cistus matorral or planted with pinus the most stable aggregates occur under matorral and may represent a lag of more resistant aggregates surviving past land use related erosional processes comparisons with aggregates under pinus however suggest that hydrophobic substances from the cistus may have increased aggregate stability aggregates from areas remaining in cultivation are the least resistant although the stability envelope overlaps with areas under pinus these differences may be related to cultivation practices whereby clay rich subsurface horizons characterized by higher proportions of expandable clays are drawn to the surface and to enhancement of aggregate stability under forest by fungal hyphae

use of selective degradation to separate preservation from productivity the assessment of diagenetic influences on the sedimentary record is problematic despite its crucial importance for accurate environmental reconstruction and understanding of biochemical cycles we propose a general applicable method that uses differences in degradation rates of organic components to separate degradation and productivity we demonstrate this method on a southeastern atlantic sediment core covering the past 145 k y the new method solves discrepancies between existing organic matter silica and carbonate based productivity reconstructions and emphasizes the importance of bottom and pore water characteristics for transformation of the sedimentary record

impact of lateglacial cold events on the northern aegean region reconstructed from marine and terrestrial proxy data marine palynomorph data paired with other indicators of sea surface hydrography planktic foraminiferal assemblages and oxygen isotopes were used to decipher the impact of cold events on the northern aegean region during the last glacial to interglacial transition the data which were derived from marine sediment cores geotusl152 and geotusl148 point to a strong impact of the heinrich 1 and younger dryas cold events on surface water conditions in the northern aegean sea shifts in marine palynomorph assemblages correlate with changes in terrestrial vegetation and climate i e precipitation and temperature reconstruc tions based on pollen assemblages in the northern borderlands of the aegean sea the climate responses of the aegean region to heinrich event 1 h1 ca 17 5 to ca 15 7 cal ka bp and younger dryas ca 12 6 to ca 11 7 cal ka bp events appear similar in magnitude with mean annual temperatures between 6 and 108c and mean annual precipitation between 300 and 450 mm however the annual temperature decline during the h1 relative to the preceding already cold conditions was minor 38c the transition from the relatively warm and humid local equivalent of the allerod interstadial to the younger dryas on the other hand witnessed an annual temperature decline of 68c and an annual precipitation decrease of 300 mm the latter occurring abruptly within only ca 150 a the return to warmer conditions in the northern aegean region after the younger dryas was completed at ca 11 6 cal ka bp copyright 2011 john wiley sons ltd

after the deluge mediterranean stagnation and sapropel formation in an east mediterranean marine core the upper sapropel begins soon after the start of a global event a very heavy precipitation which occurred in the equatorial latitudes during the late glacial early holocene this heavy precipitation in africa channelled by the nile river across 35 of latitude produced a low salinity surface layer in the east mediterranean in this confined basin with high bottom salinity the steep salinity gradient stratified the water column the stagnant bottom waters triggered the sapropel formation cretaceous sapropels in the tropical oceans may result from the same chain of events in warm humid climates with contrasting wet and dry seasonal rhythm

aerobic degradation of organic carbon inferred from dinoflagellate cyst decomposition in southern ocean sediments abstract organic carbon oc burial is an important process influencing atmospheric co2 concentration and global climate change therefore it is essential to obtain information on the factors determining its preservation the southern ocean so is believed to play an important role in sequestering co2 from the atmosphere via burial of oc here we investigate the degradation of organic walled dinoflagellate cysts dinocysts in two short cores from the so to obtain information on the factors influencing oc preservation on the basis of the calculated degradation index kt we conclude that both cores are affected by species selective aerobic degradation of dinocysts further we calculate a degradation constant k using oxygen exposure time derived from the ages of our cores the constant k displays a strong relationship with pore water o2 suggesting that decomposition of oc is dependent on both the bottom and pore water o2 concentrations

origin of low molecular weight alkylthiophenes in pyrolysates of sulphur rich kerogens as revealed by micro scale sealed vessel pyrolysis abstract micro scale sealed vessel mssv pyrolysis experiments have been conducted at temperatures of 150 200 250 300 330 and 350 c for various times on a thermally immature type ii s kerogen from the maastrichtian jurf ed darawish oil shale jordan in order to study the origin of low molecular weight lmw alkylthiophenes these experiments indicated that the lmw alkylthiophenes usually encountered in the flash pyrolysates of sulphur rich kerogens are also produced at much lower pyrolysis temperatures i e as low as 150 c as the major apart from hydrogen sulfide sulphur containing pyrolysis products mssv pyrolysis of a long chain alkylthiophene and an alkylbenzene indicated that at 300 c for 72 h no cleavage leading to generation of lmw alkylated thiophenes and benzene occurs in combination with the substantial production of lmw alkylthiophenes with a linear carbon skeleton at these conditions this indicated that these thiophenes are predominantly formed by thermal degradation of multiple poly sulfide bound linear c 5 c 7 skeletons which probably mainly originate from sulphurisation of carbohydrates during early diagenesis lmw alkylthiophenes with linear carbon skeletons seem to be unstable at mssv pyrolysis temperatures of 330 c either due to thermal degradation or to methyl transfer reactions lmw alkylthiophenes with a branched carbon skeleton most likely derive from both multiple poly sulfide bound branched c 5 c 7 skeletons and alkylthiophene units present in the kerogen

dinoflagellate cyst assemblages from the northern shelf sediments of the east china sea an indicator of marine productivity abstract the dinoflagellate cyst assemblages from the northern shelf of the east china sea were examined to assess their potential use as indicators of marine productivity in shelf environments a characteristic disparity in the species compositions of dinoflagellate cysts between coastal sediments and outer shelf sediments was observed coastal areas affected by fluvial freshwater input adjacent to the changjiang river mouth were dominated by protoperidinioid species whereas open sea shelf areas were dominated by gonyaulacoid species the rarity of protoperidinioid cysts in the shelf sediment is primarily attributable to the deficit of silicate in the waters overlying the northern east china sea shelf associated with low supplies of suspended particulate matter from the adjacent continent this would limit the growth of the protoperidinioid species which feed on diatoms in contrast a constant supply of nitrogen generated by microbial nitrogen fixation appeared to have played an important role in supporting the production of gonyaulacoid species in this shelf region thus it was determined that dinoflagellate cyst assemblages in marine sediments are closely linked to significant changes in nutrient composition leading to a selective advantage for the growth of favored taxa this result suggests that gonyaulacoid dinoflagellate cysts are a potentially useful proxy indicator for low nutrient concentration levels especially of silicate in the shelf environment

the danek edmontosaurus bonebed new insights on the systematics biogeography and palaeoecology of late cretaceous dinosaur communities1 vertebrate bonebeds are rich sources of palaeontological information throughout the world rogers et al 2007 and they have long been sources of information on dinosaur anatomy behaviour ecology growth and variability although dinosaur dominated bonebeds have been known in alberta for a long time brown 1919 sternberg 1970 they received relatively little attention during the first seven decades that dinosaurs were collected in the province this was primarily because collectors came to alberta for the relatively common well preserved articulated dinosaur skeletons that produced both new species and spectacular museum displays currie 1981 1987 since the beginning of the 1980s the dinosaur bonebeds of dinosaur provincial park have received considerable attention currie and dodson 1984 visser 1986 ryan 1992 andersen 2000 ryan et al 2001 ryan 2003 ryan and russell 2005 eberth and getty 2005 however younger bonebeds from farther north in the province have enjoyed less attention ryan et al 1995 1998 2011 eberth et al 2013 two notable exceptions are the albertosaurus bonebed near dry island buffalo jump provincial park currie and koppelhus 2010 and the pachyrhinosaurus lakustai bonebed along pipestone creek near grande prairie currie et al 2008 in and around edmonton in particular dinosaur remains have been largely ignored in the published literature bell and campione 2014 despite easy access to outcrops along the north saskatchewan river and its associated streams and creeks this special issue of the canadian journal of earth sciences increases our knowledge of edmonton s urban dinosaurs especially the iconic and serendipitously named hadrosaurid

geochemical and micropaleontological characterisation of a mediterranean sapropel s5 a case study from core ban89gc09 south of crete several geochemical and micropaleontological proxies were studied in a well developed sapropel s5 from a core collected south of crete to investigate the causes and the mechanisms of its deposition to reconstruct the paleoenvironmental and paleoceanographical conditions at time of its formation and to detect the roles played by productivity and anoxia the geochemical proxies are also used to unravel the sediment provenance and therefore to help tracing water circulation patterns and freshwater sources the multiproxy approach reveals that the sapropel layer has high internal variability and five different depositional phases can be identified four within the visible sapropel layer an increase in temperature and the development of a deep chlorophyll maximum characterise the onset of the sapropel phase 1 with enhanced productivity being favoured by local riverine input not clearly ascribable to nile river freshwater discharge and by the shoaling of the pycnocline nutricline surface water stratification and productivity develop together with strong seafloor dysoxia anoxia phase 2 is characterised by lower stratification slightly lower temperature and or higher seasonal contrast and still high productivity phase 3 records high productivity high temperature and high stratification probably more sustained by the nile input a sudden partial re oxygenation takes place at the end of this phase changing the main features of the sapropel in the fourth phase productivity starts to decrease water stratification seems to be partially broken down and sediment oxygenation increases a transitional phase phase 5 occurs between the end of the visible sapropel and the normal pelagic post sapropel sedimentation where productivity is still high and oxygenation improves compared to the visible sapropel layer the massive occurrence of polysphaeridium zoharyi cyst of a red tide forming dinoflagellate also characterises this phase the geochemical proxies indicate that pre sapropel and post sapropel sediments are quite different from each other and the provenance shifts from a more mixed to a more markedly southern origin of sediments

palaeo ecological significance transport and preservation of organic walled dinoflagellate cysts in the somali basin nw arabian sea to date relatively little information is available about factors influencing organic walled cyst production of tropical dinoflagellates and processes influencing the final burial of cysts in bottom sediments such as transport and preservation to extend this information cyst fluxes were documented for three sediment traps from june 1992 to february 1993 at two sites in the somali basin northwestern arabian sea as well as the cyst association of underlying sediments by comparing cyst associations of contemporaneously collected trap samples at different depths at one site information about transport and processes of decay in the water column was obtained neither transport nor decay appears to have any detectable influence on cyst association during cyst settlement through the water column comparing the trap associations with the underlying sediments indicates that downslope transport appears to have influenced the cyst association on a local scale only species selective decay probably related to the presence of oxygen in bottom sediments has influenced the cyst association most pronouncedly at the most offshore site relating variations in the trap associations with environmental conditions of the overlying surface waters indicates that highest production of both filled and empty cysts occurs during the sw monsoon upwelling based on this correlation three groups of species can be distinguished species with highest fluxes during 1 the first half of the sw monsoon june august bitectatodinium spongium echinidinium granulatum echindinium transparantum echinidnium spp cysts of protoperidinium compressum and cysts of protoperidinium subinerme 2 the transition between the sw monsoon and inter monsoon spiniferites mirabilis and spiniferites spp 3 no particular season all other species cyst associations of all trap samples are dominated by cyst of protoperidinium species cysts with highest fluxes during the sw monsoon form about a third of the associations

a 35 000 year record of changes in the eastern indian ocean offshore sumatra article i nfo we have examined the upper 276 cm of deep sea core bar9403 taken at a water depth of 2034 m offshore the southern portion of sumatra in the eastern indian ocean using several micropalaeontological proxies faunal counts and stable isotopes of oxygen and carbon of planktic and benthic foraminifers as well as floral counts of dinoflagellates were obtained to reconstruct conditions in the oceans over the last 35 000 years at times we found that when benthic foraminifers indicate high organic content values at the bottom of the ocean this is not paralleled by high productivity signals at the sea surface but instead must relate to changes in bottom water circulation as a result of slower water circulation the marine isotopic stages mis 3 1 are clearly differentiated by benthic and foraminiferal assemblages as well as dinoflagellates and their cysts mis 3 is characterised by a much sharper than today thermocline that was closer to the sea surface and by the absence of a low salinity barrier layer which today results from high monsoonal rains the absence of the latter persisted during the last glacial period mis 2 when bottom circulation must have been reduced and high percentages of organic matter occurred on the sea floor combined with low dissolved oxygen levels the deglaciation is marked by a change in salinity at the sea surface as seen by the dinoflagellates and planktic foraminifers and progressive alteration of the thermocline was detected by foraminifers suggesting a less productive deep chlorophyll maximum in contrast with mis 3 and 2 monsoonal activity commenced around 15 000 cal years ago and was well established 2000 years later the holocene is marked by a significant increase in river discharge to the ocean pulsed by the delivery of organic matter to the sea floor despite overall oligotrophic conditions at and near the sea surface induced by a permanent low salinity cap we did not identify obvious and persistent upwelling conditions offshore sumatra for the last 35 000 years

late quaternary environmental changes and latitudinal shifts of the antarctic circumpolar current as recorded by dinoflagellate cysts from offshore chile 41 s abstract the late quaternary organic walled dinoflagellate cyst record of site 1233 41 s offshore chile was studied with a 200 year resolution spanning the last 25 000 years the study provides the first continuous record of sub recent and recent dinoflagellate cysts in the southeast se pacific major changes in the composition of the cyst association cyst concentration and morphology of operculodinium centrocarpum reflect changes in sea surface temperature sst sea surface salinity sss palaeoproductivity and upwelling intensity these changes can be associated with latitudinal shifts of the circumpolar frontal systems the high cyst concentration high brigantedinium spp abundances low species diversity and the occurrence of certain cold water species are supportive for a 7 10 equatorward shift of the antarctic circumpolar current acc during the coldest phase of the last glacial maximum lgm between 25 and 21 1 cal ka bp deglacial warming initiated at 18 6 cal ka bp termination i 18 6 11 1 cal ka bp is interrupted by an unstable period of extreme seasonality rather than a cooling event between 14 4 and 13 2 cal ka bp synchronous with the antarctic cold reversal acr the holocene maximum is observed between 11 6 and 9 8 cal ka bp and is typified by the most southward position of the northern margin of the acc a cooling phase occurred during the early holocene until 7 cal ka bp and during the last 0 8 ka our data indicates that the se pacific 41 s climate has been influenced over the whole record by changes in the southern hemisphere sh high latitudes while during the mid to late holocene also a tropical forcing mechanism was involved including the el nino southern oscillation and the variable hadley cell intensity furthermore this study showed a relationship between the variable morphology of the spines processes of o centrocarpum and the combined variation of sea surface salinity and temperature sss sst ratio

diachronous evolution of sea surface conditions in the labrador sea and baffin bay since the last deglaciation assessing changes in sea surface conditions due to the effects of past freshwater outflow through baffin bay and davis strait to the labrador sea hereafter referred to as the baffin bay corridor

dinoflagellate cysts freshwater algae and fungal spores as salinity indicators in late quaternary cores from marmara and black seas abstract seismic profiles and mollusks have been used to suggest that from 12 500 to 7000 yr bp the black sea was an isolated freshwater lake containing potable water and implying a surface salinity of 24 and that spiniferites cruciformis spiniferites inaequalis peridinium ponticum polykrikos spp and quinquecuspis concreta characterize the lower salinity of the marmara and or black seas the core top data and correlatable down core assemblage changes in time equivalent sapropelic and brown muds show that there is no evidence for differential aerobic decay of dinocysts in the study area the main acritarchs are sigmopollis psilatum concentricystes cf c rubinus and cf acritarch 8 of traverse 1978 all of which are absent from the aegean sea and decrease in abundance with increasing salinity the first two taxa have been reported previously as freshwater species fungal remains show a similar distribution pattern to the freshwater acritarchs indicating their origin from terrestrial environments freshwater chlorococcales are almost confined to the black sea but they have rare occurrences in the aegean indicating long distance transport microforaminiferal linings are abundant in the marmara sea but are absent in deep water of the black sea in the marmara sea mid late holocene assemblages

the onset of major northern hemisphere glaciations and their impact on dinoflagellate cysts and acritarchs from the singa section calabria southern italy and dsdp holes 607 607a north atlantic abstract the climatic deterioration related to the onset of northern hemisphere glaciations circa 2 52 ma b p must have lead to reorganization and relocation of species associations and may have enhanced species turnover the present study investigates how this deterioration affects the dinoflagellate cyst and acritarch assemblages from two locations dsdp site 607 north atlantic and the singa section southern italy the records from these locations cover the interval from 2 8 to 2 2 ma with at least a 5 ka resolution and they have been correlated to the milankovitch periodicities on a cycle to cycle basis by means of integrated high resolution stable isotope calcium carbonate foraminiferal palynological and magnetostratigraphical datasets in the present study this high resolution stratigraphic framework is used for a detailed correlation of events occurring in each of the depositional sequences it also enables further assessment of the palaeoenvironmental preferences of some dinoflagellate cyst forms comparison of the two palynological records reveals a close correspondence in the timing of major assemblage changes and extinction events confirming their milankovitch cycle based correlation a close link between periods of northern hemisphere cooling at oxygen isotope stages 110 104 and 100 96 and increased dinoflagellate cyst turnover appears to be present for both dsdp site 607 and the singa section the turnover events can also be recognized in the records of planktic foraminifera and calcareous nannoplankton comparison of the singa section with site 607 and with other time equivalent marine palynological data sets shows that some oceanic taxa respond similarly over a large area the biostratigraphical implications are discussed notably the last occurrence of invertocysta lacrymosa appears to be a valuable marker for isotope stage 110 in the mediterranean and north atlantic

calcareous dinoflagellate cysts in south and equatorial atlantic surface sediments diversity distribution ecology and potential for palaeoenvironmental reconstruction several marine peridiniphycidean dinoflagellate species produce calcareous cysts during their life cycle which are relatively resistant to chemical and physical degradation and are therefore often found in large quantities in oceanic bottom sediments although the use of these calcareous cysts as proxies for palaeoenvironmental and palaeoclimatic reconstructions has seen many advances over the last decade until now only relatively patchy and regional information was available on their recent distribution patterns and ecology especially at the species level in this paper comprehensive calcareous cyst diversity and distribution data have been compiled from published and unpublished work for 167 south and equatorial atlantic ocean surface sediments ranging from 20 n to 50 s and 30 e to 65 w the main aim has been to focus on the complex often non linear relationships between individual species distributions and the physicochemical and trophic conditions of the overlying sub surface waters through the use of x y graphs of cyst abundance vs sub surface water environmental parameters and detrended correspondence analyses ten cyst species and the calcareous vegetative coccoid species thoracosphaera heimii were observed in the bottom sediments each species showing its own characteristic distribution pattern in relation to the environmental conditions of the upper water masses above them e g sea surface temperature productivity stratification the sensitive reactions of various species to unique combinations of environmental parameters shows that each species has its own specific ecological traits thus rejecting the bundled use of calcareous cyst accumulation as a general proxy for oligotrophy or stratification in future palaeoenvironmental analyses the acquired reference data set of this study is large and diverse enough to allow its future application in quantitative palaeoenvironmental reconstruction models and shows that there is still an enormous reconstruction potential concealed in many fossil calcareous dinoflagellate cyst assemblages

solid phase manganese in southeast atlantic sediments implications for the paleoenvironment abstract in many deep sea sediments mn rich layers are observed at various levels in order to investigate their formation and preservation as well as their use to reconstruct past changes in the depositional environment downcore profiles of manganese and manganese carbonate from different early diagenetic environments in the southeast atlantic ocean were examined by geochemical analysis x ray diffraction and sem analysis the results were compared to pore water data and productivity regimes in sediments underlying areas of high to moderate surface water fertility mn is reduced and recycled to overlying waters or precipitated at the oxic suboxic boundary within the sediment forming subsurface mn spikes manganese carbonate is a characteristic feature of these early diagenetic mn enrichments in the cores from the equatorial divergence where glacial interglacial productivity changes have been recorded by geochemical and isotopical evidence manganese carbonate peaks occur at deglaciation phases decreased supply of organic matter though the total manganese contents are nearly constant indicating that manganese carbonate survives burying to anoxic sediments better than mn iv phases in sediments of the central walvis ridge underlying nutrient poor surface waters peaks of mn iv and manganese carbonate occur in glacial sections thus giving evidence of higher reduction rates through increased supply of the reducing organic matter the higher flux of organic matter is attributed to a higher surface water productivity during glacials on the central walvis ridge since the evaluation of paleoproductivity proxies in that area is ambigous the interpretation of manganese and manganese carbonate profiles is an important qualitative tool supporting glacial interglacial changes in paleoproductivity

temporary repopulation by low oxygen tolerant benthic foraminifera within an upper pliocene sapropel evidence for the role of oxygen depletion in the formation of sapropels foraminiferal study of a continuous set of samples across the upper pliocene c2 sapropel singa section southern italy revealed an interval containing substantial numbers of benthic foraminifera bound by sediments in which benthic foraminifera are absent the absence of benthic foraminifera is indicative of anoxic conditions the interval with benthic foraminifera contains an association that is strongly dominated by the species bulimina marginata which is tolerant to low oxygen concentrations the bottom water oxygenation did not improve sufficiently to allow development of a more diverse benthic foraminfferal fauna or the return of intensively burrowing organisms variations in the planktic foraminiferal fauna and in the stable isotope records suggest that a surface water cooling preceded the benthic repopulation a warming seems to have coincided with the return to bottom anoxia the planktic productivity markers globigerina bulloides and neogloboquadrina show minor variations across the repopulated interval the benthic repopulation which reflects improved bottom water oxygenation was probably favored by enhanced dense water formation in response to general cooling of the surface waters

an organic geochemical perspective on terrestrialization the colonization of land required new strategies for safe gamete diaspore dispersal and to cope with desiccation harmful radiation fire and gravity accordingly the morphology behaviour and physiology of the organisms changed here we explore to what extent physiological adaptations reflected in the molecular content of the sediments add to our understanding of the terrestrialization many compounds considered characteristic of land organisms do not provide valuable information from the fossil record since 1 they were not preserved 2 they occur or correspond to substances that evolved prior to the terrestrialization e g cutan vs algaenan cellulose or 3 they have been changed diagenetically and or catagenetically the latter leads to geo macro molecules without a chemical fingerprint relating them to their original bio macro molecules despite sometimes excellent morphological preservation of the organic remains nevertheless some molecular markers and their stable isotopes provide independent information on the terrestrialization process the odd predominance of n alkane surface waxes is a feature already apparent in early land plants and could with caution be used as such furthermore fossil terpenoids and their derivatives are valuable for reconstructing the evolution of major plant groups the radiation of the phenylpropanoid pathway with for example sporopollenin and lignin seems to be closely related to the evolution of land plants as for other disciplines occupied with unravelling past life and environment organic geochemistry relies heavily on the paradigm that the present provides a key to the past for organic geochemistry the biosynthetic pathways of living organisms provide such a key the biosynthetic differences between organisms provide insight into the evolution of biosynthetic pathways and this can be applied to and calibrated against the fossil record evolution also implies adaptation and by linking species ecology to their biochemistry the adaptive value of the biosynthetic pathways and the biomolecules produced may be resolved this biosynthetic link to environment can also be applied to the past for instance the notion that oxygen is required in steroid and non hopanoid triterpenoid synthesis implies that analysis of steroids in ancient sediments may help to unravel the early evolution of the atmosphere summons et al 2006 analogous to the oxygenation of the earth s atmosphere terrestrialization also required major adaptations of the terrestrializing organisms to the living conditions on land the conquest of land required the development or strengthening of supportive structures such as skeletons stems and roots to withstand earth s gravity without the support of water and to resist wind it also demanded water saving strategies such as arthropod and plant cuticles vertebrate skin and cork to survive low humidity environments and sometimes fire as well as the development of water conducting tissues in plants roots tracheids finally the higher exposure to harmful radiation required sunscreens such as pigments aromatic and other substances as uv filters whereas the endoand exoskeletal adaptations are intrinsically based on the formation of large biopolymers water saving and uv protection may be also realized by means of smaller molecules our working hypothesis is that the major changes in biosynthetic pathways which accompanied the terrestrialization of organisms are reflected in the molecular composition of the organic matter present in palaeozoic sedimentary rocks for instance a minor change in the biosynthesis of sporopollenin may have led to lignin in return we can expect the changes in composition of the organic matter om in palaeozoic rocks to help determine following evolutionary trends the question being asked is to what extent is our working hypothesis valid and what does this provide us with to understand terrestrialization we restrict ourselves to primary producers and arthropods since they have a rich fossil record both organic geochemically and as microand macroscopic remains we exclude other terrestrial heterotrophic life forms worms snails vertebrates etc since they do not usually leave a chemically characteristic signature in the sediments from vecoli m clement g meyer berthaud b eds the terrestrialization process modelling complex interactions at the biosphere geosphere interface geological society london special publications 339 11 36 doi 10 1144 sp339 3 0305 8719 10 15 00 the geological society of london 2010 organic matter analysis lipids and

phytoplankton dynamics in the eastern mediterranean sea during marine isotopic stage 5e abstract calcareous nannoplankton diatoms and organic walled dinoflagellate cysts from seven eastern mediterranean sediment cores were investigated to clarify the climatic and paleoceanographic conditions that influenced the deposition of sapropel s5 during marine isotopic stage 5e warming of surface waters during s5 deposition is indicated by the high abundance of the calcareous nannofossil small gephyrocapsa group the presence of the dinoflagellate species spiniferites mirabilis spiniferites pachydermus lingulodinium machaerophorum and polysphaeridium zoharyi and the tropical subtropical diatom pseudosolenia calcar avis chaetoceros resting spores rhizosolenids and thalassionema group increased productivity accompanied s5 deposition as evidenced by a general decrease in abundance of calcareous nannofossil superficial species and a coeval increase of dinocysts and diatoms the productivity increase is further supported by an increase of the deep dwelling calcareous nannofossil species florisphaera profunda stratification of near surface waters is recorded by the presence of the dinocyst species l machaerophorum and p zoharyi together with the co occurrence of the diatom chaetoceros resting spore group thalassionema frauenfeldii and thalassionema nitzschioides var parva which reflect transport of neritic waters off shore and by the presence of some freshwater and transport related diatom taxa cyclotella diatomella and diploneis gradual shoaling of the nutricline and a gradual weakening of water stratification at the end of s5 deposition is indicated by an increase in the deep dwelling calcareous nannoplankton species gladiolithus flabellatus which suggests a less deep niche compared to the deeper dwelling f profunda time transgressive variations in the distribution of the calcareous nannofossil emiliana huxleyi and changes in the abundances of gephyrocapsa oceanica small gephyrocapsa g flabellatus and of the dinocysts p zoharyi and l machaerophorum lead to paleocirculation considerations as they always reflect the main current path moreover the occurrence of upwelling related diatom and dinocyst taxa such as chaetoceros resting spores and s pachydermus suggests the presence of a former gyre structure south of crete that was active during s5 time

distribution of organic walled dinoflagellate cysts in surface sediments of the southern ocean eastern atlantic sector between the subtropical front and the weddell gyre abstract thirty two surface sediment samples from the southern ocean eastern atlantic sector between the subtropical front and the weddell gyre were investigated to provide information on the distribution of modern organic walled dinoflagellate cysts in relation to the oceanic fronts of the antarctic circumpolar current acc a clearly distinguishable distribution pattern was observed in relation to the water masses and fronts of the acc the dinoflagellate cysts of species characteristic of open oceanic environments such as impagidinium species are highly abundant around the subtropical front whereas south of this front cosmopolitan species such as nematosphaeropsis labyrinthus and the cysts of protoceratium reticulatum characterise the transition from subtropical to subantarctic surface waters the subantarctic surface waters are dominated by the cysts of heterotrophic dinoflagellates such as protoperidinium spp and selenopemphix antarctica the cysts of protoperidinium spp form the dominant part of the assemblages around the antarctic polar front whereas s antarctica concentrations increase further to the south the presence of s antarctica in sediments of the maud rise a region of seasonal sea ice cover reflects its tolerance for low temperatures and sea ice cover a previously undescribed species cryodinium meridianum gen nov sp nov has a restricted distribution pattern between the antarctic polar front and the acc weddell gyre boundary

the relationship between neogene dinoflagellate cysts and global climate dynamics abstract the neogene period 23 03 2 58 ma underwent a long term relatively gradual cooling trend culminating in the glacial interglacial climate of the quaternary palaeoclimate studies on the neogene have provided important information for understanding how modern patterns of atmospheric and oceanic circulation developed and how they may relate to wider environmental change here we use a newly created global database of neogene dinoflagellate cysts the tertiary oceanic parameters information system topis to investigate how dinoflagellate cysts recorded the cooling of neogene surface marine waters on a global scale species with warm and cold water preferences were determined from previously published literature and extracted from the database percentages of cold water species were calculated relative to the total number of species with known temperature preferences from each site and compared throughout the neogene at differing latitudes overall the percentage of cold water species increases gradually through the neogene this trend indicates a gradual global cooling that is comparable to that reported from other marine and terrestrial proxies this also demonstrates the use of dinoflagellate cysts in determining temperature change on both extended temporal and wide geographical scales the increase in the percentage of cold water species of dinoflagellate cysts recorded worldwide from the early and middle miocene to the late pliocene indicates a global scale forcing agent on neogene climate such as co2

mediterranean functioning and sapropel formation respective influences of climate and hydrological changes in the atlantic and the mediterranean abstract during ocean drilling program odp legs 160 and 161 sapropels were recovered both in the western and eastern mediterranean this obliges to a reassessment of the previous studies focused on sapropels from only the eastern mediterranean and to consider the changes which occurred in the mediterranean climate but also in the water characteristics both in the atlantic and in the western mediterranean in the north atlantic the position of the polar front which migrated southwards during glacial times and the melting of northern ice caps during interglacial periods together with the convection in the labrador and norwegian seas appear essential to control the salinities of the waters facing the strait of gibraltar the salinities of the surface and intermediate layers constitute the first driving force of the mediterranean dynamics the second driving force being the mediterranean climate the stagnation of deep waters leading to sapropel deposition in the western mediterranean may be explained by a drastic weakening of the density difference between mediterranean outflow and atlantic intermediate waters facing the strait of gibraltar this weakening was induced primarily by the salinity decrease of atlantic surface water and secondly by a rather high salinity in the atlantic intermediate layer rather than by a drastic deterioration of the mediterranean climate this scenario probably concerns most of the sapropel events and it may be used for the knowledge of atlantic and mediterranean functioning over climatic changes

interglacial variability mis 5 and mis 7 and dinoflagellate cyst assemblages in the bay of biscay north atlantic the interglacial periods of the late quaternary are frequently investigated as they constitute potential analogues for our modem climate and may shed light on the key questions of natural climate variability and future developments the aim of this work is to reconstruct the paleoenvironmental history of marine isotope stages mis 5 and 7 in deep sea sediments of the northern bay of biscay north east atlantic ocean on the basis of a multiproxy compilation including analysis of dinoflagellate cyst assemblages we discuss the nature of the paleoenvironmental and paleoclimate changes that took place in this region recurrent successions of species marking the beginning and the termination of the interglacial complexes mis 5 and mis 7 revealed a coherent scheme of water mass migration during these key transitional periods moreover our data extend knowledge about the ecology of several dinoflagellate taxa in particular we discuss the ecology of spiniferites septentrionalis and note that this species can be used as a biostratigraphical tracer in north atlantic quaternary sediments until a major event of iceberg calving occurred during mis 6 dated to around 150 ka bp the dinocyst spinferites mirabilis appears to be an important proxy for recognizing warm intervals within interglacial complexes during mis 5e the last interglacial this species is represented by the highest percentages ever recorded in sediments from the north atlantic region peak occurrence of this species during mis 7 indicates that substage mis 7c the second warm interval of the penultimate interglacial represents the climatic optimum during the mis 7 interglacial complex

palaeoenvironmental information gained from calcareous dinoflagellates the late quaternary eastern and western tropical atlantic ocean in comparison abstract the environmental preferences of calcareous dinoflagellates have been investigated over the last 140 ka by comparing material from two sediment cores one from the highly productive equatorial divergence of the eastern atlantic ocean and the other from the low productivity western tropical atlantic ocean pronounced differences in palaeoproductivity between the two sediment cores are indicated by high and variable organic carbon accumulation rates in the east in contrast to relatively constant and low values in the west calcareous dinoflagellates show just the opposite pattern high accumulation rates in the west and lower in the east at the equatorial divergence temporal variations of calcareous dinoflagellate and organic carbon accumulation rates show for the most part an inverse relationship high calcareous dinoflagellate content coincides with low organic carbon accumulation rates and vice versa in the investigated region and time interval enhanced production of calcareous dinoflagellates can be correlated to periods of reduced palaeoproductivity probably related to relatively stratified conditions of the upper water column

palynofacies analysis and organic walled dinoflagellate cysts as indicators of palaeo hydrographic changes an example from holocene sediments in skalafjord faroe islands abstract this study documents holocene variations in organic matter deposition from ca 6350 cal yr bc to ad 1430 in skalafjord faroe islands and uses this information to assess palaeo hydrographic conditions the chronology of the interval studied is based on five ams 14 c ages based on the total sedimentary organic content the sediments dating to ca 6350 cal yr bc to ad 160 have been deposited under dysoxic bottom water conditions suggesting good ventilation in the water column the sediments dating to ca ad 160 1090 have been deposited under decreasing oxygen availability from ad 1090 to 1430 suboxic bottom water conditions characterised the fjord high terrestrial influx characterised most sediments in the study interval however moderate terrestrial influx was recorded in sediments dating to ca 6350 5670 cal yr bc based on the dinoflagellate cyst assemblages changes in the nutrient availability were inferred in the waters of the fjord over the study period the nutrients were minimal at ca 6350 5670 cal yr bc they increased in the interval ca 5670 685 cal yr bc and became very abundant at ca 685 cal yr bc to ad 1260 a decreasing trend in nutrient availability was inferred in sediments of age ca ad 1260 1430 a qualitative approach was used for the reconstruction of holocene sea surface temperature conditions based on dinoflagellate cyst and acritarch assemblages the estimated sea surface parameters highlighted the mid holocene final stage of the climatic optimum ca 6350 5300 cal yr bc the neo glaciation period ca 5300 cal yr bc to ad 260 a general climatic amelioration during the period ca ad 260 1090 and a cooling at ca ad 1090 1260

the potential of organic walled dinoflagellate cysts for the reconstruction of past sea surface conditions in the southern ocean abstract in this study we investigate the potential of organic walled dinoflagellate cysts dinocysts as tools for quantifying past sea surface temperatures sst in the southern ocean for this purpose a dinocyst reference dataset has been formed based on 138 surface sediment samples from different circum antarctic environments the dinocyst assemblages of these samples are composed of phototrophic gonyaulacoid and heterotrophic protoperidinioid species that provide a broad spectrum of palaeoenvironmental information the relationship between the environmental parameters in the upper water column and the dinocyst distribution patterns of individual species has been established using the statistical method of canonical correspondence analysis cca among the variables tested summer sst appeared to correspond to the maximum variance represented in the dataset to establish quantitative summer sst reconstructions a modern analogue technique mat has been performed on data from three late quaternary dinocyst records recovered from locations adjacent to prominent oceanic fronts in the atlantic sector of the southern ocean these dinocyst time series exhibit periodic changes in the dinocyst assemblage during the last two glacial interglacial cycles during glacial conditions the relative abundance of protoperidinioid cysts was highest whereas interglacial conditions are characterised by generally lower cyst concentrations and increased relative abundance of gonyaulacoid cysts the mat palaeotemperature estimates show trends in summer sst changes following the global oxygen isotope signal and a strong correlation with past temperatures of the last 140 000 years based on other proxies however by comparing the dinocyst results to quantitative estimates of summer ssts based on diatoms radiolarians and foraminifer derived stable isotope records it can be shown that in several core intervals the dinocyst based summer ssts appeared to be extremely high in these intervals the dinocyst record seems to be highly influenced by selective degradation leading to unusual temperature ranges and to unrealistic palaeotemperatures we used the selective degradation index kt index to determine those intervals that have been biased by selective degradation in order to correct the palaeotemperature estimates we show that after correction the dinocyst based ssts correspond reasonably well with other palaeotemperature estimates for this region supporting the great potential of dinoflagellate cysts as a basis for quantitative palaeoenvironmental studies

selective aerobic and anaerobic degradation of lipids and palynomorphs in the eastern mediterranean since the onset of sapropel s1 deposition abstract selective degradation of organic matter in sediments is important for reconstructing past environments and understanding the carbon cycle here we report on compositional changes between and within lipid classes and kerogen types represented by palynomorph groups in relation to the organic matter flux to the sea floor and oxidation state of the sediments since the early holocene for central eastern mediterranean site abc26 this includes the initially oxic but nowadays anoxic presapropelic interval the still unoxidised lower part of the organic rich s1 sapropel its postdepositionally oxidised and nowadays organic poor upper part as well as the overlying postsapropelic sediments which have always been oxic a general 2 3 times increase in terrestrial and marine input during sapropel formation is estimated on the basis of the total organic carbon toc pollen spore dinoflagellate cyst n alkane n alkanol and n alkanoic acid concentration changes in the unoxidised part of the sapropel the long chain alkenones 1 15 diols and keto ols loliolides and sterols indicate that some plankton groups notably dinoflagellates may have increased much more apart from the terrestrial and surface water contributions to the sedimentary organic matter anomalous distributions and preservation of some c 23 c 27 alkanes alkanols and alkanoic acids have been observed which are interpreted as a contribution by organisms living in situ comparison of the unoxidised s1 sapropel with the overlying oxidised sapropel and the organic matter concentration profiles in the oxidised postsapropelic sediments demonstrates strong and highly selective aerobic degradation of lipids and palynomorphs there seems to be a fundamental difference in degradation kinetics between lipids and pollen which may be possibly related with the absence of sorptive preservation as a protective mechanism for palynomorph degradation the n alkanes impagidinium and nematosphaeropsis are clearly more resistant than toc the n alkanols and n carboxylic acids are about equally resistant whereas the pollen all other dinoflagellate cysts and other lipids appear to degrade considerably faster which questions the practice of normalising to toc without taking diagenesis into account selective degradation also modifies the relative distributions within lipid classes whereby the longer chain alkanes alcohols and fatty acids disappear faster than their shorter chain equivalents accordingly interpretation of lipid and palynomorph assemblages in terms of pre or syndepositional environmental change should be done carefully when proper knowledge of the postdepositional preservation history is absent two lipid based preservation proxies are tested the diol keto ol oxidation index based on the 1 15c 30 diol and keto ols doxi and the alcohol preservation index api whereby the former seems to be the most promising

taphonomy age and paleoecological implication of a new pachyrhinosaurus dinosauria ceratopsidae bonebed from the upper cretaceous campanian wapiti formation of alberta canada the grande prairie region alberta canada includes some of the richest cretaceous fossil sites in north america including the recently described bonebed of pachyrhinosaurus lakustai at the pipes

postdepositional aerobic and anaerobic particulate organic matter degradation succession reflected by dinoflagellate cysts the madeira abyssal plain revisited abstract we report on the succession of selective degradation of dinoflagellate cyst species that can be considered representative for discrete particulate organic matter pom classes of different degradability the effects of anaerobic and aerobic degradation as well as bioturbation in a natural setting are documented in high resolution by means of palynological and geochemical analyses on madeira abyssal plain a and f turbidites these turbidites are unique as their initial ungraded sediments are affected by a downward penetrating oxydation front geochemical analyses document the presence of an active downward penetrating oxidation front in the a turbidite and a palaeo oxidation front in the f turbidite in this latter turbidite several zones can be distinguished from top to bottom an oxidised bioturbated zone an oxidised but not bioturbated zone a visible paleo oxidation front and a narrow nitrogenous zone overlying unoxidised sediments we are the first to report that anaerobic degradation within the nitrogenous zones in both turbidites affects cysts of some heterotrophic dinoflagellates the cyst species affected echinidinium aculeatum echinidinium spp cysts of protoperidinium monospinum and brigantedinium spp exponentially decrease in this zone that is further characterised by a strong decrease in sulphur content due to sulphide oxidation degradation rates are different for each species these cysts of heterotrophic dinoflagellates consist of a nitrogen rich glycan in contrast to the cellulosic cysts walls of phototrophic dinoflagellates therefore our observation supports the hypothesis that the quality of organic matter plays an important role in om degradation in oxygen deficient environments with n rich om being more labile than other components in these environments all heterotrophic species are strongly affected by aerobic degradation with their cyst concentrations exponentially decreasing with increasing oxygen exposure degradation rates vary between species and range von highly degradable to slightly degradable most strongly affected are cysts of protoperidinium monospinum brigantedinium spp and echinidinium spp increasingly less affected are selenopemphix nephroides selenopemphix quanta other peridinioids and echinidinium aculeatum an effect of aerobic degradation on photosynthetic species could only be observed for pentapharsodinium dalei all impagidinium species appeared to be resistant to aerobic degradation despite having analysed only a limited number of samples in the bioturbated zone of the f turbidite we have strong indications that the bioturbation can lead to the degradation of pom that is not affected by aerobic degradation alone the cyst species spiniferites ramosus impagidinium paradoxum lingulodinium machaerophorum nematosphaeropsis labyrinthus spiniferites spp impagidinium sphaericum spiniferites elongates and spiniferites mirabilis do not show concentration changes in the non bioturbated aerobic sediments but their concentrations are considerably decreased in the bioturbated part of the f turbidite this supports the hypothesis that bioturbation can increase the degradation of pom by e g increasing oxygen exposure time and or by an alteration of aerobic and anaerobic conditions we furthermore show that the degradation rates of pom components represented by individual cyst species differ between zones with different redox and biological conditions this implies that pom degradation reaction rate coefficients are environment dependent our observation that dinoflagellate cyst species have different degradation rates ranging from extremely labile to extremely recalcitrant within the individual redox bioturbation zones supports the hypothesis that cyst walls have a species specific molecular structure our results support continuum models of organic matter degradation that assume a continuous distribution of organic matter reactivity

pliocene holocene evolution of depositional conditions in the eastern mediterranean role of anoxia vs productivity at time of sapropel deposition a multiproxy geochemical study of nine sapropel layers from odp hole 964a odp leg 160 in the eastern mediterranean spanning the pliocene holocene time interval provides new insights into the evolution of sapropel deposition paleoenvironmental proxies were used for reconstruction of productivity ba derived from marine barite oxygen conditions trace metal ratios and sedimentary regime clay minerals detrital elements these proxies reveal a significant increase in river runoff relative to decreasing aeolian input during sapropel deposition over the whole time interval ba excess supports the argument that a significant increase in export productivity is the main triggering mechanism for sapropel deposition although preservation also played an important role furthermore major differences exist in depositional conditions including both oxygenation and productivity since the pliocene productivity fluctuated substantially and was higher during the pliocene and pleistocene than during the holocene at the same time decreasing oxygen availability parallels the enhanced productivity dysoxic to anoxic conditions appear to coincide with marine productivity maxima thus suggesting that oxygen depletion may be linked to greater consumption rather than restricted circulation this correspondence supports the hypothesis that productivity fluctuations resulting from climate oscillations were the main cause of enhanced organic matter contents and also a main controlling factor for reduced oxygen availability

sulphidic mediterranean surface waters during pliocene sapropel formation sapropels organic matter rich layers are common in neogene sediments of the eastern mediterranean sea the formation of these layers has been attributed to climate related increases in organic matter production1 2 3 and increased organic matter preservation due to oxygen depletion in more stagnant bottom waters2 3 here we report that eastern mediterranean pliocene sapropels4 contain molecular fossils of a compound isorenieratene known to be synthesized by photosynthetic green sulphur bacteria suggesting that sulphidic euxinic and therefore anoxic conditions prevailed in the photic zone of the water column these sapropels also have a high trace metal content which is probably due to the efficient scavenging of these metals by precipitating sulphides in a euxinic water column the abundance and sulphur isotope composition of pyrite are consistent with iron sulphide formation in the water column we conclude that basin wide water column euxinia occurred over substantial periods during pliocene sapropel formation in the eastern mediterranean sea and that the ultimate degradation of the increased organic matter production was strongly influential in generating and sustaining the euxinic conditions