morphological and abundance variations in homotryblium cyst assemblages related to depositional environments uppermost oligocene lower miocene jylland denmark abstract abundant occurrences of homotryblium dinoflagellate cysts have been interpreted as reflecting deposition in near shore marginal marine areas either in hypersaline or low salinity environments it has also been suggested that the process length of homotryblium cysts is related to proximity to the coast the present study provides new insights in the ecology of homotryblium and adds important information about the use of the morphological variations of homotryblium cysts for environmental reconstructions it presents an example where homotryblium cysts show high relative abundances in a low salinity partly restricted marine depositional environment four different species of homotryblium were recorded homotryblium additense is proposed as a new species the regional palaeogeographic distribution of the four species h additense homotryblium vallum homotryblium plectilum and homotryblium tenuispinosum shows a distinct depositional proximal distal distribution pattern h additense occurs only in a narrow stratigraphic interval in the most proximal part of the study area h vallum only occurs sporadically mainly in the proximal parts of the study area h plectilum dominates the proximal areas while h tenuispinosum dominates the more distal areas variations in abundance and cyst type also seem to respond to systems tracts sequence boundaries and flooding surfaces the observed distributional patterns of homotryblium species strongly indicate a response to the salinity of the depositional environment it is further suggested that at least some of the recorded species of homotryblium originated from the same motile dinoflagellate species producing cysts of different morphology in response to variations in salinity a phenomenon known from extant dinoflagellates

climatic and environmental changes across the early eocene climatic optimum at mid waipara river canterbury basin new zealand abstract the cretaceous paleogene marine sedimentary succession exposed in the banks of the middle reaches of the waipara river referred to as mid waipara north canterbury new zealand has been the subject of several high profile studies of paleogene paleoclimate over the past decade it is one of relatively few sections globally where a multi proxy approach is possible due to the good preservation of microfossils and organic biomarkers the eocene section is also well dated by magnetostratigraphy and biostratigraphy based on planktic foraminifera calcareous nannofossils and dinoflagellate cysts dinocysts here we build on this previous work and undertake a comprehensive analysis of paleontological and geochemical indicators of climatic and environmental changes through the early middle eocene part of the section with particular focus on the early eocene climatic optimum eeco 53 26 49 14 ma we correlate a 33 5 m thick interval with the eeco based on biostratigraphy magnetostratigraphy tex86 paleothermometry and bulk carbonate 13c our new sea surface temperature sst record based on tex86 agrees with a previous lower resolution record based on tex86 and planktic foraminiferal 18o and mg ca ratios the eeco interval in this section extends from the upper part of the new zealand waipawan stage to the mangaorapan heretaungan stage boundary at 49 27 ma the eeco onset is not exposed but the termination is well constrained by a fall in sst and shift to more positive 13c values six negative carbon isotope excursions cies are recognised within the eeco and are tentatively correlated with cies j k m o q t and c22nh4 in the global 13c compilation the cies are associated with warmer ssts indicating that they represent hyperthermals the bayspar tex86 calibration indicates sst increased by as much as 12 c from the early eocene 55 ma to the eeco where sst peaked at 35 c sst gradually declined from mid eeco 51 ma into the middle eocene the marked warming in the early eeco is associated with the highest abundance of warm water taxa in calcareous nannofossil and dinocyst assemblages the highest proportion of planktic foraminifera and a coeval long term shift to abundant angiosperm vegetation primarily driven by a rise in casuarinaceae there is good agreement between tex86 and marine microfossil based proxies for temperature providing confidence that both approaches are useful guides to past water temperature warm water marine taxa are most abundant in the eeco but are not dominant comparison of the abundance of nannofossil warm water taxa between mid waipara and a low latitude site on shatsky rise suggests the latitudinal temperature gradient between mid and low latitudes in the eeco was greater than the tex86 proxy implies there is no clear evidence for enhanced sedimentation rates associated with the eeco in contrast to evidence from the nearby mead stream section superabundant homotryblium a euryhaline dinocyst in the early and middle eeco suggests elevated salinity and or stratified surface waters and there is no clear evidence of increased surface productivity associated with the eeco declining sst in the late eeco 50 ma corresponds with an increase in cool water taxa and terrigenous material this article highlights the importance of combining well calibrated paleontological and geochemical records to better constrain and understand past warm climate states

quantifying the role of geographic change in cenozoic ocean heat transport using uncoupled atmosphere and ocean models abstract a series of five cenozoic atmospheric general circulation model agcm experiments has been performed using a new set of paleogeographic reconstructions for 55 40 33 20 and 14 ma the five continental reconstructions incorporate the tectonic evolution of early eocene to middle miocene continental positions and topography with all other model boundary conditions and forcings held constant the series of agcm experiments captures a

recognition of cyclic and non cyclic environmental changes in the mediterranean pliocene a palynological approach the interval between 2 8 and 2 3 ma b p from the south italian singa section has been investigated for its dinoflagellate cyst and sporomorph contents in order to facilitate palaeoenvironmental interpretation the following curves are derived from the data the ratios sporomorphs dinoflagellate cysts protoperidinioid gonyaulacoid dinoflagellate cysts warm cold water indicating dinoflagellate cysts inner neritic oceanic dinoflagellate cysts outer neritic oceanic dinoflagellate cysts and the reworked dinoflagellate cysts per gram of sediment furthermore the already available 18o curve has been used calibration of changes in the sporomorph dinoflagellate ratio against the computed astronomical insolation curve leads to an improved age assessment for the section frequency analysis on the curves shows the 23 41 and 100 ka frequency components to be most important phase and amplitude differences between the filtered 23 41 and 100 ka frequency components are used for environmental interpretation the 23 ka frequency band is best explained by changes in runoff induced transport the 41 ka frequency components are classified in a group with short response time to orbital forcing and a group with longer response time those signals having a short response time are attributed to local precipitation induced changes in runoff those signals having a longer response time are mainly attributed to changes in global temperature and to a lesser extent to changes in global ice volume finally longer term cyclic and non cyclic changes are mainly attributed to temperature and sea level variation

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

high resolution 104 years deep sea foraminiferal stable isotope records of the eocene oligocene climate transition we have constructed high resolution 104 105 years benthic foraminiferal 13c and 18o records for the upper eocene through lower oligocene of two pelagic sequences deep sea drilling project dsdp site 522 in the angola basin south atlantic ocean and ocean drilling program odp site 744 in the southern indian ocean these records provide improved constraints on both the timing and magnitude of marine oxygen and carbon isotope events from 30 to 35 ma the oxygen isotope records indicate that the ubiquitous 18o increase oi 1 which marks the rapid expansion of continental ice sheets and a minimum of 3 to 4 c of cooling of bottom waters in the earliest oligocene 33 6 ma occurred in 350 kyr more than half the transition occurred over the final 40 50 kyr this period of lower temperatures and widespread continental glaciation persisted for roughly 400 kyr i e the duration of magnetochron c13n these records also indicate that this interval was characterized by at least two 100 kyr waxing and waning cycles oi 1a and oi 1b and possibly several higher frequency events the benthic foraminiferal 13c records show a positive 0 8 excursion that is nearly isochronous with the oi 1 oxygen isotope increase similar magnitude 13c increases at other sites indicate this was a global phenomenon suggestive of an unusually large perturbation to the carbon cycle this excursion was followed by smaller amplitude 13c oscillations with periods of roughly 400 kyr we suspect that the ubiquitous oi 1 13c excursion resulted from a brief but substantial increase in export production and carbon burial

pleistocene marine and periglacial deposits of the english channel the pleistocene marine and associated periglacial deposits of the coasts of southern england from cornwall to sussex the british channel islands and northern france from brittany and normandy to the pas de calais are described the deposition of almost all marine deposits is ascribed to temperate conditions although large igneous erratic boulders may have been emplaced by shore ice rafting at the end or beginning of cold stages the balance of the evidence from a variety of dating methods including u series dating amino acid geochronology and biostratigraphy of associated terrestrial formations indicates that deposits of the last three pre holocene temperate marine oxygen isotope stages stages 9 7 and substage 5e can readily be identified along much of both coastlines of the channel deposits attributable to stages 11 and 13 are uncommon and best seen in the staircase of marine terraces backing the hampshire sussex coastal plain and perhaps in western brittany and the boulonnais the height above modern sea level of the marine deposits is thought to be the result of slow uplift of the coastal zone caused by the isostatic response to sediment unloading during accelerated phases of erosion in cold stages although deep seated tectonics also may have been partly responsible for uplift however the height above modern sea level of a deposit alone is not on its own an indicator of age periglacial head deposits are mainly exposed along the coasts with the sections showing frost shattered debris moved downslope by cryoreptation frost creep the age of these deposits is uncertain although they appear to be principally of marine oxygen isotope stages 4 and 2 in age some remnants of marine oxygen isotope stage 6 or 8 head deposits are present both in england and northern france in a few places with good dating control head deposits dating to the marine oxygen isotope stage 12 can be recognised the age of the head deposits in most sections is based on their stratigraphical relationship with loess palaeosols and on the dating of the underlying raised beaches copyright 2003 john wiley sons ltd

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

the oligocene maikop series of lahich eastern azerbaijan paleoenvironment and oil source rock correlation abstract the maikop formation deposited in eastern azerbaijan during oligocene and early miocene represents a prolific source unit for the oils found within the southern gobustan area and the kura depression based on biomarker characteristics the oils are believed to have originated from a clastic source rock deposited in an anoxic to suboxic transitional marine environment with low to moderate input of terrigenous organic matter however due to the thermal immaturity of accessible maikop rocks oil source rock correlation based on biomarker fingerprints is hampered the results from a sedimentary succession sampled in the shemakha gobustan area near the village of lahich revealed the presence of marginally mature rr 0 6 0 7 maikop rocks based on lithology geochemical data and paleontological analyses the sampled section contains upper eocene and lower oligocene sediments palynological analyses of dinoflagellate cysts indicate an early rupelian to early chattian oligocene age for the upper part of the investigated maikop succession however the stratigraphic position of the middle and lower part of the succession remains unclear maceral composition as well as biomarker and stable isotope c n data indicate a major contribution of aquatic organisms and variable inputs from macrophytes and land plants to organic matter deposition during the oligocene microbial communities most probably included heterotrophic bacteria and cyanobacteria as well as green sulfur bacteria higher inputs of terrigenous organic matter occurred during deposition of the lower part of the succession increased remineralisation of organic matter in the water column is suggested to result in low toc and hydrocarbon contents as well as 15n enriched total nitrogen of the eocene to earliest oligocene sediments organic carbon accumulation during the oligocene occurred in a stratified episodically euxinic environment this is indicated by low toc s ratios and higher contents of aryl isoprenoids in several samples from the upper units a moderate to good oil source rock correlation with oils from the kura depression is indicated by sterane and triterpane fingerprints as well as carbon isotopic composition of hydrocarbon fractions

palaeogeographical changes in response to glacial interglacial cycles as recorded in middle and late pleistocene seismic stratigraphy southern north sea offshore stratigraphic records from the north sea contain information to reconstruct palaeo ice sheet extent and understand sedimentary processes and landscape response to pleistocene glacial interglacial cycles we document three major middle to late pleistocene stratigraphic packages over a 401 km2 area norfolk vanguard boreas offshore wind farm offshore east anglia uk through the integration of 2d seismic borehole and cone penetration test data the lowermost unit is predominantly fluviatile yarmouth roads formation marine isotope stage mis 19 13 including three northward draining valleys the middle unit swarte bank formation records the southernmost extent of tunnel valley fills in this area of the north sea providing evidence for subglacial conditions most likely during the anglian stage mis 12 glaciation the yarmouth roads and swarte bank deposits are truncated and overlain by low energy estuarine silts and clays brown bank formation mis 5d 4 smaller scale features including dune scale bedforms and abrupt changes in cone penetration test parameters provide evidence for episodic changes in relative sea level within mis 5 the landscape evolution recorded in deposits of mis 19 5 are strongly related to glacial interglacial cycles although a distinctive aspect of this low relief ice marginal setting are opposing sediment transport directions under contrasting sedimentary process regimes

middle and late pleistocene glacial lakes of lowland britain and the southern north sea basin focusing on lowland britain and the southern north sea basin this article reviews the sedimentary and geomorphic evidence for the main glacial lakes inferred during the middle and late pleistocene and evaluates their impacts on drainage basin development glacial lakes are best known from glaciations during marine isotope stages mis 12 6 and 2 although glacial lakes have also been inferred during mis 10 and 4 some lakes for example bosworth low level humber and the lakes of the eastern fenland margin are reconstructed from unequivocal sedimentary evidence including rhythmites and subaqueous outwash whereas others lakes for example lapworth and fenland are inferred mostly from erosional features and remain to be substantiated the largest known glacial lake developed in the southern north sea basin between an ice sheet to the north and a chalk bedrock ridge in the strait of dover area first during the anglian elsterian glaciation of mis 12 and again during the late wolstonian late saalian drenthe glaciation of mis 6 the palaeohydological impacts of lake drainage are thought to include cutting of the strait of dover as a result of catastrophic drainage from the north sea lake during mis 12 incision of a number of gorges and river valleys in england and diversion or even reversal of major rivers such as the thames and the proto soar avon system recently varve chronologies have been correlated with the greenland ice core record although caution is needed to discriminate between varves and non annual rhythmites future work on pleistocene glacial lakes needs to test chronologies of lake development by luminescence dating of glaciolacustrine sediments deposited in non ice proximal locations 1 fine grained rainout deposits and 2 wave rippled sands deposited in shallow water and to model the impacts of glacial isostasy in order to reconstruct lake extents all of this work should be based on the rigorous application of sedimentology to interpret sedimentary facies and depositional environments

catastrophic flooding origin of shelf valley systems in the english channel britain became geographically isolated from continental europe when high interglacial seas flooded the shallow english channel and north sea shelf areas but a tenuous link remained the weald artois chalk ridge between southeast england and northwest france just how this isthmus was breached making britain an island has been a matter of conjecture a new bathymetric map of the sea floor may solve the mystery it reveals a large bedrock floored valley containing landforms including grooves and streamlined islands consistent with a megaflood event caused when a rock dam at the dover strait breached draining a large pro glacial lake in the north sea basin a hypothesis for the permanent isolation of britain from mainland europe during interglacial high sea levels has been confirmed gupta et al analysed a new regional bathymetric map of part of the area finding a valley with landforms indicating large scale subaerial erosion by high magnitude water discharges they suggest breaching of a rock dam at the dover strait instigated drainage of a large lake in the north sea basin megaflood events involving sudden discharges of exceptionally large volumes of water are rare but can significantly affect landscape evolution continental scale drainage patterns and climate change1 it has been proposed that a significant flood event eroded a network of large ancient valleys on the floor of the english channel the narrow seaway between england and france2 3 4 this hypothesis has remained untested through lack of direct evidence and alternative non catastrophist ideas have been entertained for valley formation5 6 here we analyse a new regional bathymetric map of part of the english channel derived from high resolution sonar data which shows the morphology of the valley in unprecedented detail we observe a large bedrock floored valley that contains a distinct assemblage of landforms including streamlined islands and longitudinal erosional grooves which are indicative of large scale subaerial erosion by high magnitude water discharges our observations support the megaflood model in which breaching of a rock dam at the dover strait instigated catastrophic drainage of a large pro glacial lake in the southern north sea basin2 we suggest that megaflooding provides an explanation for the permanent isolation of britain from mainland europe during interglacial high sea level stands7 and consequently for patterns of early human colonisation of britain together with the large scale reorganization of palaeodrainage in northwest europe4

the earliest occupation of north west europe a coastal perspective recent discoveries from pakefield and happisburgh britain have provided clear evidence for an unexpectedly early hominin occupation of north west europe the sites found in the deposits of interglacial rivers and estuaries on the southern rim of the ancient north sea coast span the older and younger parts of the cromerian complex stage the older of these sites pre date 0 5 ma based on the presence of a mimomys micromammal fauna and may be as old as 0 78 1 0 ma on the european continent stone artefacts unambiguously as old derive from the mediterranean the earliest archaeological evidence that has been discovered inland in europe north of the alps is associated with an arvicola fauna younger than 0 5 ma and was deposited in temperate conditions near rivers that flowed into the north sea only after the cromerian complex is there evidence for hominin activity in cooler conditions and also in locations east of the rhine valley this spatial and temporal pattern in site distribution occurs despite the long history of research in north west europe and the presence of deposits of the same age from both the coast and rivers this paper explores the idea that the changes in site distribution before and after the cromerian complex signal that early hominin occupation in northern europe during the earlier period was an atlantic phenomenon i e restricted to the milder temperate climates in the coastal continental regions dispersal to more inland habitats originated in the coastal regions the conditions explaining preservation of the oldest sites from a geological perspective are investigated providing a geographical climatological and habitat context for the wider surroundings of the sites because of differences in the potential for preserving archaeology in fluvial and coastal contexts poor long term preservation of coastal depositional contexts and low numbers of sites it is difficult to disentangle the influence of hominin habitat preference or even tolerance from habitat preservation however the hypothesis that the earliest hominins in europe were restricted to the temperate atlantic parts of europe provides a testable framework for evaluating future archaeological discoveries and makes it possible to formulate research strategies for locating new hominin occupation sites in europe especially its atlantic regions

inter annual climate variability in europe during the oligocene icehouse abstract new sclerochronological data suggest that a variability comparable to the north atlantic oscillation nao was already present during the middle oligocene about 20 myr earlier than formerly assumed annual increment width data of long lived marine bivalves of oligocene 30 25 ma strata from central europe revealed a distinct quasi decadal climate variability modulated on 2 12 mainly 3 7 year cycles as in many other modern bivalves these periodic changes in shell growth were most likely related to changes in primary productivity which in turn were coupled to atmospheric circulation patterns stable carbon isotope values of the shells 13 c shell further corroborated the link between shell growth and food availability sub decal oscillations in the 3 7 year band in other annually resolved fossil archives were often interpreted as el nino southern oscillation enso cycles this possibility is discussed in the present study however combined shell derived proxy and numerical climate model data lend support to the interpretation of a nao like variability according to numerical climate models winter sea level pressure wslp and precipitation rate wpr across central europe during the oligocene exhibited a pattern similar to the modern nao the simulated nao index for the oligocene shows periodicities coherent with those revealed by the proxy data 2 5 6 years yet on shorter wavelengths than the modern nao biennial and 6 10 year cycles likely the different paleogeography and elevated atmospheric co 2 concentrations not only influenced the sea level pressure pattern but also the temporal variability of the nao precursor the present study represents the first attempt to characterize the inter annual climate variability in central europe during the oligocene and sets the basis for future studies on the early phase of the cenozoic icehouse climate state

fossils from quaternary fluvial archives sources of biostratigraphical biogeographical and palaeoclimatic evidence fluvial sedimentary archives have the potential to preserve a wide variety of palaeontological evidence ranging from robust bones and teeth found in coarse gravel aggradations to delicate insect remains and plant macrofossils from fine grained deposits over the last decade advances in quaternary biostratigraphy based on vertebrate and invertebrate fossils primarily mammals and molluscs have been made in many parts of the world resulting in improved relative chronologies for fluviatile sequences complementary fossil groups such as insects ostracods and plant macrofossils are also increasingly used in multi proxy palaeoclimatic and palaeoenvironmental reconstructions allowing direct comparison of the climates and environments that prevailed at different times across widely separated regions this paper reviews these topics on a regional basis with an emphasis on the latest published information and represents an update to the 2007 review compiled by the flag inspired igcp 449 biostratigraphy subgroup disparities in the level of detail available for different regions can largely be attributed to varying potential for preservation of fossil material which is especially poor in areas of non calcareous bedrock but to some extent also reflect research priorities in different parts of the world recognition of the value of biostratigraphical and palaeoclimatic frameworks which have been refined over many decades in the core regions for such research particularly for the late middle and late pleistocene of nw europe has focussed attention on the need to accumulate similar palaeontological datasets in areas lacking such long research histories although the emerging datasets from these understudied regions currently allow only tentative conclusions to be drawn they represent an important stage in the development of independent biostratigraphical and palaeoenvironmental schemes which can then be compared and contrasted

global cooling accelerated by early late eocene impacts at ocean drilling program site 689 maud rise southern ocean 18o records of fine fraction bulk carbonate and benthic foraminifers indicate that accelerated climate cooling took place following at least two closely spaced early late eocene extraterrestrial impact events a simultaneous surface water productivity increase as interpreted from 13c data is explained by enhanced water column mixing due to increased latitudinal temperature gradients these isotope data appear to be in concert with organic walled dinoflagellate cyst records across the same microkrystite bearing impact ejecta layer in the mid latitude massignano section central italy in particular the strong abundance increase of thalassiphora pelagica is interpreted to indicate cooling or increased productivity at massignano because impact induced cooling processes are active on time scales of a few years at most the estimated 100 k y duration of the cooling event appears to be too long to be explained by impact scenarios alone this implies that a feedback mechanism such as a global albedo increase due to extended snow and ice cover may have sustained impact induced cooling for a longer time after the impacts

the central paratethys during oligocene as an ancient counterpart of the present day black sea unique records from the coccolith limestones abstract four isochronous oligocene coccolith limestone horizons from the carpathians were examined in order to reconstruct paleoceanographic conditions in the central paratethys the dominance of small and size uniform pyrite framboids the occurrence of low diversity dinoflagellate cysts and coccolithophorids and the presence of biomarker molecule 28 30 dinorhopane indicate that the water column was stratified with the upper water column being relatively well oxygenated but the bottom water being anoxic the latter is confirmed by the fine and consistent horizontal laminations in various parts of the basin scarcity of benthic organisms and their trace fossils the limestones exhibit typical marine 13c values but are significantly depleted in 18o and enriched in 87sr relative to contemporaneous ocean water these isotopic compositions result from a decreased salinity of the surface waters caused by an increased riverine input this is confirmed by the lack or impoverishment of planktonic foraminifers presence to abundance of goniodomid dinoflagellate cysts and massive occurrence of low diversity nannoplankton assemblages which indicates decreased salinities as low as 17 and high productivity in the upper water column these observations indicate that the limestones were formed during periods when connection of the central paratethys with the global ocean was limited which impeded water exchange causing the development of low salinity conditions of surface water and bottom water anoxia during the deposition of the oldest tylawa horizon primary productivity was enhanced and chemocline was positioned exceptionally high in the water column moreover decreased 13c values in both carbonates and organic matter of this horizon suggest that widespread methane venting took place in the basin during np23 all these data show that during the oligocene the central paratethys experienced similar conditions to those of the current black sea which can be used as a modern analogue especially for the tylawa horizon therefore the tylawa horizon can be perceived as a potential effect of future post depositional processes of coccolith marls analogous to those having been deposited in the black sea for 2 7 kyr

palaeogeography europe cut adrift the floor of the english channel provides evidence for two catastrophic floods arising from the drainage of huge glacial lakes in the area of the southern north sea these megafloods made britain what it is today britain became geographically isolated from continental europe when high interglacial seas flooded the shallow english channel and north sea shelf areas but a tenuous link remained the weald artois chalk ridge between southeast england and northwest france just how this isthmus was breached making britain an island has been a matter of conjecture a new bathymetric map of the sea floor may solve the mystery it reveals a large bedrock floored valley containing landforms including grooves and streamlined islands consistent with a megaflood event caused when a rock dam at the dover strait breached draining a large pro glacial lake in the north sea basin

comment on m sarnthein h e stremme and a mangini the holstein interglaciation time stratigraphic position and correlation to stable isotope stratigraphy of deep sea sediments

late quaternary paleoproductivity and deep water circulation in the eastern south atlantic ocean evidence from benthic foraminifera abstract two late quaternary sediment cores from the northern cape basin in the eastern south atlantic ocean were analyzed for their benthic foraminiferal content and benthic stable carbon isotope composition the locations of the cores were selected such that both of them presently are bathed by north atlantic deep water nadw and past changes in deep water circulation should be recorded simultaneously at both locations however the areas are different in terms of primary production one core was recovered from the nutrient depleted walvis ridge area whereas the other one is from the continental slope just below the coastal upwelling mixing area where present day organic matter fluxes are shown to be moderately high recent data served as the basis for the interpretation of the late quaternary faunal fluctuations and the paleoceanographic reconstruction during the last 450 000 years nadw flux into the eastern south atlantic ocean has been restricted to interglacial periods with the strongest dominance of a nadw driven deep water circulation during interglacial stages 1 9 and 11 at the continental margin high productivity faunas and very low epibenthic 13c values indicate enhanced fluxes of organic matter during glacial periods this can be attributed to a glacial increase and lateral extension of coastal upwelling the long term glacial interglacial paleoproductivity cycles are superimposed by high frequency variations with a period of about 23 000 yr enhanced productivity in surface waters above the walvis ridge far from the coast is indicated during glacial stages 8 10 and 12 during these periods cold nutrient rich filaments from the mixing area were probably driven as far as to the southeastern flank of the walvis ridge

the holstein interglaciation time stratigraphic position and correlation to stable isotope stratigraphy of deep sea sediments marine molluscan shells from para type and other loclities of the holsteinian interglaciation were dated by thu and the electron spin resonance esr method to more than 350 000 and 370 000 yr b p beyond the limit of thu dating the high age estimate is corroborated by a kar age of 420 000 yr b p determined from volcanic ash near the base of the ariendorf paleosol in the middle rhine valley believed to be a pedostratigraphic equivalent of the holsteinian shells from the herzeele marine unit iii an equivalent of the wacken domnitz warm stage in northern france and subsequent to the holsteinian revealed ages between 300 000 and 350 000 yr b p a correlation of these two warm stages with marine oxygen isotope stages 11 and 9 on the specmap and cartune time scales is suggested from the benthic oxygen isotope record one may infer that no exceptionally high global sea level rise corresponds to the large transgressions of the holstein sea in northern germany therefore a significant proportion of the transgression was probably the result of an unusually large local glacial isostatic depression caused by the extreme buildup of ice during the preceding elster glaciation stage 12 according to the deep sea record it lasted approximately 50 longer than the subsequent cold stage 10 the outstanding soil formation with braunlehm and the well developed thermal optimum of the holsteinian are tentatively related to a phase of minimum sea ice cover in the norwegian greenland sea as deduced from long benthic carbon isotope records from the central atlantic

the impact of the north atlantic ocean on the younger dryas climate in northwestern and central europe the main results of multiproxy climate reconstructions for the younger dryas and experiments carried out with an atmospheric general circulation model are discussed quantitative temperature inferences for northwestern and central europe show that winter conditions were remarkably extreme with values of 20 30 c below that of today annual temperature ranges with a continental signature 30 34 c were reconstructed for the entire study area compared with today the greatest cooling was experienced in the seaboard area the comparison of the climate reconstructions and simulation experiments indicates that sea ice in the north atlantic ocean played a decisive role in the climate of the study area by cooling the surface air temperatures and by controlling the position of the storm track surface air circulation was westerly even during younger dryas winters a slight northward shift of the mean atlantic sea ice margin during winter may explain the proposed subdivision of the younger drays into a phase of maximum cold and humidity succeeded by a less cold and relatively dry phase 1998 john wiley sons ltd

the rauenberg fossil lagerstatte baden wurttemberg germany a window into early oligocene marine and coastal ecosystems of central europe abstract the oligocene was a period of profound climatic and biotic changes coinciding with a shift from a mostly ice free warmhouse world at the eocene oligocene boundary to a globally cooler more seasonal climate the rauenberg locality baden wurttemberg germany is one of the most significant early oligocene fossil assemblages in europe containing both marine and terrestrial elements of fauna and flora preservation is often superb and comprises complete and articulated skeletons with soft tissue preservation the diverse assemblage provides critical insights into the paleoenvironment of the upper rhine valley we reassess diversity at the locality resulting in a list of 302 taxa found at the site 207 of which are marine 52 of taxa represented by macrofossils the rest are interpreted as originating from the coastal environment molluscan echinoderm and plant macrofossil diversity are assessed here for the first time based on these new results we interpret rauenberg as representing a fully marine assemblage deposited in a moderately shallow low energy tropical subtropical environment productivity was high and seafloor anoxia was intermittently developed there is no evidence for long term brackish influence or mangrove swamps and no direct evidence for the development of seagrass meadows on land warm frost free conditions permitted the development of prevailingly evergreen sclerophyllous broad leaved forests along with pine and palm rich coastal forests on sandy soils the marine invertebrate fauna shows more northerly affinities whereas the vertebrate fauna is distinctly paratethyan

dinoflagellate cyst zonation for the middle to upper eocene in the austral basin southwestern atlantic ocean implications for regional and global correlation the well exposed marine eocene units from southwestern patagonia argentina contain useful information for reconstructing regional climate and oceanographic patterns in an area adjacent to the drake passage the aim of this paper is to integrate dinoflagellate cyst data from three sections of the southwestern austral basin rio turbio formation to propose a zonation scheme which can be applied to other southwestern atlantic ocean sites assemblages of organic walled dinoflagellate cysts have been analysed in different cropping out sections and cores showing the high potential of this fossil group as biostratigraphic markers comparison of dinoflagellate cyst events of the upper member of the rio turbio formation with calibrated biostratigraphic ranges in the palaeogene south pacific ocean allowed us to date and correlate these sedimentary sections the resulting zonation consists of four dinoflagellate cyst zones labelled rtf 1 to rtf 4 between the middle lutetian and late priabonian as a final point we applied dinoflagellate cyst species with importance as palaeoenvironmental markers to assess long term climatic and oceanographic evolution for the area this study shows that the endemic antarctic dinoflagellate cyst assemblage is dominant during the middle to late eocene rtf 1 to rtf 3 while a significant replacement of these taxa by cosmopolitan species characterizes the upper part of the upper member of the rio turbio formation rtf 4 this turnover seems to be a consequence of changes in the ocean circulation patterns forced by deepening of the southern atlantic gateways the drake passage and the tasman gateway

paleoclimatic and paleoenvironmental records of the oligocene miocene transition central jylland denmark a multidisciplinary study of the oligocene miocene o m transition was carried in two boreholes harre 1 and horn 1 from the danish land area in order to improve the understanding of the paleodimatological and environmental changes across the mi 1 the earliest miocene cooling event dinoflagellate cyst dinocyst biostratigraphy supported by re evaluation of the foraminiferid biostratigraphy a new set of magnetic data and stable carbon isotope delta c 13 records were applied to improve the age model for the studied succession as well as the positioning of the o m boundary these data further enabled a correlation of the two investigated profiles with the well established stratigraphical framework for the danish area the bit index an organic proxy indicating the relative input of soil derived organic matter dinocyst assemblages and palynofacies have been applied for establishing the paleoenvironmental changes across the oligocene miocene o m boundary our data indicate a shallowing upward trend in the latest oligocene resulting in the establishment of a very restricted marine setting in the earliest miocene our study confirms that the o m boundary is located at a sequence boundary the local sequence boundary b sb b and corresponds to an increase in terrestrial organic matter input a mean air temperature record based on the mbt cbt proxy reveals an similar to 2 degrees c drop in temperature at the o m and the sequence boundary our findings confirm previous suggestions that this sequence boundary is a result of the glacio eustatic sea level fall related with the mi 1 cooling event the unconformity at the sequence boundary probably correlates with the coldest part of mi 1 and thus no deposits from this period have been preserved this suggests that the temperature drop might have been greater than 2 degrees c

middle eocene through early oligocene climate history and paleoceanography in the southern ocean stable oxygen and carbon isotopes from odp sites on maud rise and kerguelen plateau mackensen a and ehrman w u 1992 middle eocene through early oligocene climate history and paleoceanography in the southern ocean stable oxygen and carbon isotopes from odp sites on maud rise and kerguelen plateau mar geol 108 l 27 paleogene stable oxygen and carbon isotopes were measured in foraminifera from odp sites 689 and 690 at maud rise in the atlantic ocean sector of the southern ocean and from sites 738 744 748 and 749 at the southern kerguelen plateau in the indian ocean sector these data were compared with sedimentological data from the same sample set both benthic and planktic 6180 values document a cooling trend beginning around 49 5 ma at all sites during the late middle eocene planktic lso values indicate a steepening latitudinal temperature gradient from 14 c at the northern sites towards 10 c at the southernmost sites terrigeneous sand grains of probably ice rafted origin and clay mineral assemblages point to the existence of a limited east antarctic ice cap with some glaciers reaching sea level as early as middle eocene time around 45 5 ma between 45 and 40 ma average paleotemperatures were between 5 and 7 c in deep and intermediate water masses while near surface water masses ranged between 6 and io c during the late eocene between 40 and 36 ma average temperatures further decreased to 4 5 c in the deep and intermediate water masses and to 5 8 c near the sea surface abruptly increasing 61so values at approximately 35 9 ma exactly correlate with a sharp pulse in the deposition of icerafted material on the kerguelen plateau a dramatic change in clay mineral composition and an altered southern ocean circulation indicated by a differentiation of benthic 61 c values between sites increasing opal concentrations and decreasing carbonate contents for planktic and benthic foraminifera this 80 increase ranges between 1 0 and 1 3 o and between 0 9 and 1 4 o respectively we favour a hypothesis that explains most of the 61so shift at 35 9 ma with a buildup of a continental east antarctic ice sheet consequently relatively warm oligocene antarctic surface water temperatures probably are explained by a temperate wet based nature of the ice sheet this would also aid in the fast build up of an ice sheet by enhancing the moisture transport on to the continent

multiproxy approach to understanding the origin of cretaceous pelagic limestone marl alternations dsdp site 391 blake bahama basin limestone marl alternations are usually directly interpreted to reflect cyclic palaeoenvironmental signals however uncertainty in such interpretations stems from the differential diagenesis that most limestone marl alternations have undergone differential diagenesis results in markedly different alterations between limestones and marls and in the loss of comparability of many measurable parameters for an unequivocal interpretation of the origin of rhythmic alternations diagenetically robust parameters or parameters that clearly indicate the degree of diagenetic bias are required the present study uses a multiproxy approach independent biotic sedimentary and geochemical parameters in order to unravel the palaeoenvironmental signal recorded in valanginian early cretaceous limestone marl alternations from the blake bahama basin dsdp site 391 using this approach terrestrial and marine influences can be distinguished changes in nutrient levels estimated and prediagenetic differences in the non carbonate fraction constrained surprisingly no systematic variations in any of these parameters were observed between limestone and marl layers implying that none of these was directly responsible for the formation of the rhythmic alternation hence none of the current models of sedimentary formation of limestone marl rhythmites is applicable here calcareous nannofossils are equally well preserved in limestone and marl layers ruling out their dissolution in marl layers as a source of the calcite cement in the limestone beds sr values of 700 900 p p m indicate that aragonite may have been present in the original pelagic sediment the assumption of fine grained sedimentary aragonite imported from nearby carbonate platforms as the source of the cement would explain a number of otherwise enigmatic features in these rhythmites including the source of the calcite cement observed in the limestones the equally good preservation of calcareous nannofossils in limestones and marls and the higher concentration of calcareous nannofossils in marl layers the study demonstrates that examination of diagenetically inert parameters or parameters in which diagenetic effects can be filtered can yield unexpected results clearly careful analysis of such parameters needs to be undertaken in order to make reliable palaeoenvironmental interpretations from rhythmite successions

differentiation of mis 9 and mis 11 in the continental record vegetational faunal aminostratigraphic and sea level evidence from coastal sites in essex uk multidisciplinary investigations of the vegetational faunal and sea level history inferred from the infills of buried channels on the coast of eastern essex have a direct bearing on the differentiation of mis 11 and mis 9 in continental records new data are presented from cudmore grove an important site on mersea island that can be linked to the terrace sequence of the river thames the vegetational history has been reconstructed from a pollen sequence covering much of the interglacial represented the temperate nature of the climate is apparent from a range of fossil groups including plant remains vertebrates especially the rich herpetofauna molluscs and beetles which all have strong thermophilous components the beetle data have been used to derive a mutual climatic range reconstruction suggesting that mean july temperatures were about 2 c warmer than modern values for southeast england whereas mean january temperatures may have been slightly colder the sea level history has been reconstructed from the molluscs ostracods and especially the diatoms which indicate that the marine transgression occurred considerably earlier in the interglacial cycle than at the neighbouring hoxnian site at clacton there are a number of palynological similarities between the sequence at cudmore grove and clacton especially the presence of abies and the occurrence of azolla filiculoides megaspores moreover both sites have yielded palaeolithic archaeology indeed the latter is the type site of the clactonian flake and core industry however the sites can be differentiated on the basis of mammalian biostratigraphy new aminostratigraphic data as well as the differences in the sea level history the combined evidence suggests that the infill of the channel at cudmore grove accumulated during mis 9 whereas the deposits at clacton formed during mis 11 the infill of a much later channel yielding non marine molluscs and vertebrates including hippopotamus appears to have formed during the ipswichian mis 5e this evidence is compared with other important sites of late middle pleistocene age in britain and elsewhere on the continent and the importance of a multidisciplinary approach is stressed

bartonian to priabonian dinoflagellate cyst biostratigraphy and paleoenvironments of the m karcha section in the southern tethys margin rif chain northern morocco abstract palynological analyses were performed on the eocene sediments of the m karcha section which is located in the taza region structural tsoul unit eastern external rif northeastern morocco the palynological content of this section is composed essentially of well preserved and diverse dinoflagellate cyst assemblages allowing detailed taxonomic determinations age assignments biostratigraphic correlations and paleoenvironmental interpretations other palynomorphs such as spores pollen grains and foraminiferal linings are rare and therefore not taxonomically determined up to the genus level 131 dinoflagellate cyst species were identified age assignments are based on dinocyst bioevents considered previously as potential biostratigraphic markers of the bartonian and priabonian including the lowest occurrences los of glaphyrocysta semitecta impagidinium dispertitum rhombodinium perforatum cooksonidium capricornum stoveracysta ornata stoveracysta sp 2 of brinkhuis and biffi 1993 and lo and highest occurrence ho of schematophora speciosa the quantitative palynological analyses based mainly on dinoflagellate cysts through the m karcha section revealed an inner neritic generally lagoon environment with a low productivity alternated with short episodes of the open marine influence

pliocene paleoclimatic reconstruction using dinoflagellate cysts comparison of methods the application of quantitative and semiquantitative methods to assemblage data from dinoflagellate cysts shows potential for interpreting past environments both in terms of paleotemperature estimates and in recognizing water masses and circulation patterns estimates of winter sea surface temperature wsst were produced by using the impagidinium index ii method and by applying a winter temperature transfer function tfw estimates of summer sea surface temperature ssst were produced by using a summer temperature transfer function tfs two methods based on a temperature distribution chart act and actpo and a method based on the ratio of gonyaulacoid protoperidinioid specimens g p wsst estimates from the ii and tfw methods are in close agreement except where impagidinium species are sparse ssst estimates from tfs are more variable the value of the g p ratio for the pliocene data in this paper is limited by the apparent sparsity of protoperidinioids which results in monotonous ssst estimates of 14 26 c the act methods show two biases for the pliocene data set taxonomic substitution may force matches yielding incorrect temperature estimates and the method is highly sensitive to the end points of species distributions dinocyst assemblage data were applied to reconstruct pliocene sea surface temperatures between 3 5 2 5 ma from dsdp hole 552a and odp holes 646b and 642b which are presently located beneath cold and cool temperate waters north of 56 n our initial results suggest that at 3 0 ma wssts were a few degrees c warmer than the present and that there was a somewhat reduced north south temperature gradient for all three sites it is likely that sssts were also warmer but by an unknown perhaps large amount past oceanic circulation in the north atlantic was probably different from the present

late quaternary dinoflagellate cysts from the black marmara and aegean seas variations in assemblages morphology and paleosalinity abstract the link between sea surface salinity sss and dinoflagellate cyst morphology was studied quantitatively in cores of late quaternary mud from the black marmara and aegean seas where oxygen isotopic and planktonic foraminiferal data show salinities of about 5 19 15 22 and 36 39 ppt respectively in the black sea late glacial muds contain low diversity assemblages of the cruciform species spiniferites cruciformis and pyxidinopsis psilata with most s cruciformis cysts having expanded septal membranes form 1 circular outline form 2 irregular the assemblage is associated with surface salinities of in the northeast aegean core stenohaline species and morphotypes are rare occurring only as low percentages of s cruciformis forms 3 and 4 and o centrocarpum var truncatum in a mid holocene sapropel that was deposited during a period of high runoff and black sea water outflow marmara sea cores record surface salinities of 14 18 ppt during late glacial sapropel deposition and 20 22 ppt for the overlying marine sediments the sapropel is dominated by s cruciformis forms 1 and 2 and by p psilata with common l machaerophorum clavate and normal forms in surface sediments l machaerophorum is co dominant with o centrocarpum normal and truncate forms brigantedinium and spiniferites spp percentages of s cruciformis five forms and l machaerophorum two forms plotted against proxy salinity data however show no clear correlation indicating that morphological variation is not a simple function of salinity

african monsoons an immediate climate response to orbital insolation the croll milankovitch astronomical theory of climate1 3 has received strong support from the evidence of a linear climatic forcing by obliquity and precession although nonlinearity had to be assumed for eccentricity4 5 moreover interglacials have appeared to be controlled by the orbital insolation6 although a phase shift of 6 000 5 000 yr is seen between an astronomical climate index and terrestrial climate indicators dominated by the northern ice sheet dynamics climate proxy data of low latitudes are less directly dependent on the ice sheets here it is shown that during the past 464 000 yr african monsoons signalled by the east mediterranean sapropels were heaviest always and only when a northern summer monsoon index computed from the orbital variation of insolation reached maximum values this occurred during all the interglacials but also twice during glacial periods thus tropical aridity is not the single climatic pattern of glacial periods an immediate terrestrial climate response to orbital variations of insolation is established

short term fluctuations in vegetation and phytoplankton during the middle eocene greenhouse climate a 640 kyr record from the messel oil shale germany the palaeogene was the most recent greenhouse period on earth especially for the late palaeocene and early eocene several superimposed short term hyperthermal events have been described including extremes such as the palaeocene eocene thermal maximum major faunal and floral turnovers in the marine and terrestrial realms were recorded in association with these events high resolution palynological analysis of the early middle eocene maar lake sediments at messel near darmstadt germany provides an insight into the dynamics of a climax vegetation during the middle eocene greenhouse climate in a time span without significant climatic excursions numerical techniques like detrended correspondence analysis and wavelet analysis have been applied to recognize cyclic fluctuations and long term trends in the vegetation through a time interval of approximately 640 kyr based on the numerical zoning of the pollen diagram three phases in the development of the vegetation may be distinguished throughout these phases the climax vegetation did not change substantially in qualitative composition but a trend towards noticeably less humid conditions probably in combination with a drop of the water level in the lake may be recognized a shift in algal population from the freshwater dinoflagellate cyst messelodinium thielepfeifferae to a dominance of botryococcus in the uppermost part of the core is interpreted as a response to changes in acidity and nutrient availability within the lake time series analyses of pollen assemblages show that variations in the milankovitch range of eccentricity obliquity and precession can be distinguished in addition fluctuations in the sub milankovitch range are indicated this demonstrates that floral changes during steady depositional conditions in the middle eocene of messel were controlled by orbital forcing

paleoenvironmental evolution of the paratethys in the slovenian basin during the late paleogene several sections from the uppermost eocene and oligocene of northern slovenia have been investigated with respect to sedimentary facies foraminiferal assemblages stable isotopes carbonate microfacies and palynology the main objective was to reconstruct the paleoenvironmental history of the paleogene paratethys in this region of the eastern alpine realm the sediments exhibit a transgressive succession beginning with conglomerates sandstones and mudstones of fluvial and lacustrine origin followed by carbonates and muddy marls indicating marine conditions the foraminiferal faunal changes from brackish to shallow marine to deeper marine assemblages and the distribution of the palynofloras corroborate the sedimentological results microfacies analysis of the limestones shows a wide variation of shallow water generally mud rich facies dominated by coralline algae foraminifera and corals microfaunas adapted to low oxygen conditions indicate temporal sluggish bottom water circulation which can be associated with high fresh water fluxes these results are discussed as reflecting both the global sea level rise during the early oligocene and the regional tectonic and climatic evolution

new ph sensor for hydrothermal fluids the ph values of subsurface hydrothermal fluids remain controversial and largely unknown because of the difficulties of measuring them in situ this paper presents a new method for evaluating the ph of hydrothermal fluids from analyses of halogen concentrations in hydrous minerals this method is general and can be used to study water rock interactions in a variety of geologic environments an example of the method9s application to the salton sea geothermal systems california is given

the pleistocene rivers of the english channel region the pleistocene history of river systems that enter the english channel from northern france and southern england is reviewed during periods of low sea level cold stages these streams were tributaries of the channel river in southern england the largest the river solent is an axial stream that has drained the hampshire basin from the early pleistocene or late pliocene other streams of southern england may be of similar antiquity but their records are generally short and their sedimentary history have been destroyed as in northern brittany by coastal erosion and valley deepening as a consequence of tectonic uplift in northern france the seine and somme rivers have very well developed terrace systems recording incision that began at around 1 ma the uplift rate deduced from the study of these terrace systems is of 55 to 60 m myr 1 since the end of the early pleistocene generally the facies and sedimentary structures indicate that the bulk of the deposits in these rivers accumulated in braided river environments under periglacial climates in all the area around the channel evolution of the rivers reflects their responses to climatic change local geological structure and long term tectonic activity in this context the middle somme valley is characterised by a regular pattern in which incision occurs at the beginning of each glacial period within a general background of uplift nevertheless the response of the different rivers to climatic variations uplift and sea level changes is complex and variable according to the different parts of the river courses copyright 2003 john wiley sons ltd

middle pleistocene interglacial deposits at barling essex england evidence for a longer chronology for the thames terrace sequence results are presented from a multidisciplinary study of fossiliferous interglacial deposits on the northern side of the thames estuary these fill a channel cut into london clay bedrock and overlain by the barling gravel a thames medway deposit equivalent to the lynch hill and corbets tey gravels of the middle and lower thames respectively the channel sediments yielded diverse molluscan and ostracod assemblages both implying fully interglacial conditions and a slight brackish influence pollen analysis has shown that the deposits accumulated during the early part of an interglacial plant macrofossils particularly the abundance of trapa natans reinforce the interglacial character of the palaeontological evidence a beetle fauna which includes four taxa unknown in britain at present has allowed quantification of palaeotemperature using the mutual climatic range method tmax 17 to 26 c tmin 11 to 13 c a few vertebrate remains have been recovered from the interglacial deposits but a much larger fauna as well as palaeolithic artefacts is known from the overlying barling gravel the age of the interglacial deposits is inferential the geological context suggests a late middle pleistocene interglacial part of the post diversion thames system and therefore clearly post anglian this conclusion is supported by amino acid ratios from the shells of freshwater molluscs the correlation of the overlying barling gravel with the lynch hill corbets tey aggradation of the thames valley constrains the age of the barling interglacial to marine oxygen isotope stages 11 or 9 the presence of corbicula fluminalis and pisidium clessini confirms a pre ipswichian marine oxygen isotope substage 5e age and their occurrence in the early part of the interglacial cycle at barling precludes correlation with marine oxygen isotope stage 11 as these taxa occur only later in that interglacial at sites such as swanscombe and clacton thus by process of elimination a marine oxygen isotope stage 9 age would appear probable

sea level and deep water temperature changes derived from benthic foraminifera isotopic records we show that robust regressions can be established between relative sea level rsl data and benthic foraminifera oxygen isotopic ratios from the north atlantic and equatorial pacific ocean over the last climatic cycle we then apply these regressions to long benthic isotopic records retrieved at one north atlantic and one equatorial pacific site to build a composite rsl curve as well as the associated confidence interval over the last four climatic cycles our proposed reconstruction of rsl is in good agreement with the sparse rsl data available prior to the last climatic cycle we compute bottom water temperature changes at the two sites and at one southern indian ocean site taking into account potential variations in north atlantic local deep water 18o our results indicate that a last glacial maximum lgm enrichment of the ocean mean oxygen isotopic ratio of 0 95 is the lowest value compatible with unfrozen deep waters in the southern indian ocean if local deep water 18o did not increase during glacials with respect to present such a value of the lgm mean ocean isotopic enrichment would impose a maximum decrease in local bottom water 18o at the north atlantic site of 0 30 during glacials

review and new aspects concerning the formation of eastern mediterranean sapropels abstract in this paper it is proposed that the formation of eastern mediterranean sapropels occurred in an anti estuarine type of circulation which was to some degree weakened relative to the present in response to reduction of the eastern mediterranean excess of evaporation over freshwater input this reduction of excess evaporation would have been imposed by intensifications of 1 the indian ocean summer sw monsoon influencing the eastern mediterranean via increased nile discharge and 2 the system of mediterranean depressions an element of the westerly atlantic system causing increased precipitation and decreased evaporation both the indian ocean summer monsoon and the westerly atlantic system would be intensified in response to the occurrence of distinct minima in the cycle of precession it is demonstrated that reduced excess evaporation whether or not coinciding with global phases of deglaciation would lead to reduction of surface water salinities in the eastern mediterranean causing isolation of previously formed high salinity cooler deep water thus mixing was severely reduced possibly even restricted to eddy diffusion with only occasional convective events that because of the existing density gradient hardly ever would reach the deepest parts of the basin the consequently diminished oxygen advection down from a few hundred meters in the water column favoured preservation of the sinking organic matter this would however suffice only to enable the formation of sapropels with low organic carbon contents the high organic carbon contents observed in various sapropels are argued to reflect superimposed increases of export production the described scenario accounts for previously reported 1 increases of organic carbon content with increasing depth of deposition within individual sapropels and 2 asymmetrical sequences of sapropel deposition characterized by gradual build up and rather abrupt ending it is furthermore in agreement with 3 isotopic and faunal reconstructions of the history of exchange transports through both the strait of sicily and the strait of gibraltar and 4 faunal and floral reflections of the presence or absence of a distinct deep chlorophyll maximum with its associated increases in export production indicating the presence or absence of a shallow pycnocline within the euphotic layer moreover the described scenario 5 is in no way conflicting with the reports of sapropels in the western mediterranean and 6 seems to be endorsed by occasionally intercalated intervals suggestive of somewhat improved oxygenation amidst anoxic benthic desert levels a situation that has been observed in a few quaternary and pliocene sapropels

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

hydrocarbon potential and depositional environments of oligo miocene rocks in the eastern carpathians vrancea nappe romania abstract the oligocene to early miocene fine grained succession in the eastern carpathians includes from base to top the lower menilite lmm bituminous marl bmm lower dysodilic shale ldsm and upper dysodilic shale udsm members these stratigraphic units constituting the main hydrocarbon source rocks in the eastern carpathians have been studied in an outcrop section to determine its depositional environment and hydrocarbon potential the lmm contains high amounts of toc but because of low thickness its source potential is limited the organic matter of the overlying bmm is mainly derived from autochthonous marine organisms including bacterial biomass toc contents are moderate because of dilution by carbonate minerals calcareous nannoplankton dates the bmm into nannoplankton zones np21 22 salinity and redox conditions varied from reduced to slightly enhanced and from strictly anoxic to dysoxic the ldsm contains carbonate free black shale and sandstone beds deposited in a depositional lobe under anoxic conditions despite of high hi values land plants form a significant part of the organic matter channel fill sediments form the top of the ldsm the lower part of the early miocene udsm accumulated in a lobe whereas its upper part represents a basin plain setting mttc ratios reflect a trend from slightly enhanced to slightly decreased normal marine salinity the presence of aryl isoprenoids suggests a temporary photic zone anoxia controlled by salinity variations both marine and terrestrial biomass contributed to the organic matter a major change towards oxic conditions occurred at the boundary between the udsm and the overlying gura soimului formation the studied succession can generate 6 t of hydrocarbons per square meter all members are oil prone but yield oil with different biomarker characteristics this allows the identification of oil generated from different lithostratigraphic units

paleocene sea level and productivity changes at the southern tethyan margin el kef tunisia integrated analysis of quantitative distribution patterns of organic walled dinoflagellate cysts dinocysts and benthic foraminifera from the paleocene el kef section nw tunisia allows the reconstruction of sea level and productivity fluctuations our records indicate that the environment evolved from an initially oligotrophic open marine outer neritic to upper bathyal setting towards a more eutrophic inner neritic setting influenced by coastal upwelling by the end of the paleocene an overall second order change in paleodepth is reflected by both microfossil groups from the base of planktic foraminifera zone p4 onwards the main phase of shallowing is evidenced by an increase of inner neritic dinocysts of the areoligera group disappearance of deeper water benthic foraminifera and increasing dominance of shallow marine taxa several buliminids haplophragmoides spp trochammina spp the total magnitude of this shallowing is obscured by interaction with a signal of eutrophication but estimated to be around 150 m from 200 to 50 m superimposed on the overall trend third order sea level fluctuations have been identified and correlated to sequences in other regions paleoproductivity indicators notably protoperidinioid dinocysts and buliminids show a trend from an oligotrophic to a eutrophic setting d 2005 elsevier b v all rights reserved

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 eocene sea retreat from the tarim basin west china and concomitant asian paleoenvironmental change the paleogene sediments of the southwest tarim basin along the west kunlun shan in western china include the remnants of the easternmost extent of a large epicontinental sea this shallow sea once extended across the eurasian continent before it retreated westward and eventually separated as the paratethys sea climate modeling results suggest that this sea retreat is an equally important forcing mechanism as the tibetan plateau uplift in the aridification of the asian continental interior and the intensification of the asian monsoon system the age and paleogeography of the retreat are poorly constrained hindering the understanding of its cause and paleoenvironmental impacts this study reports litho and biostratigraphic results from two sections recording the last major regression out of the tarim basin that is expressed by a regional transition from marine clastics and limestones to continental red beds rich micro and macrofossil assemblages including benthic foraminifera ostracods bivalves calcareous nannofossils and organic walled dinoflagellate cysts dinocysts indicate a shallow proximal and marine environment strong similarity to assemblages known from central asia and europe confirms that surface ocean connections extended across eurasia from the tarim basin to the western tethys during the latest eocene moreover the recovered fossil associations date the last marine sediments as earliest priabonian in age 37 ma overlap between dinoflagellate mps interval zone and calcareous nannofossil zone cp 14 the retreat of the sea from the tarim basin is time equivalent with the sea level lowstand at the bartonian priabonian boundary but pre dates both the oligocene miocene regional uplift of the pamir mountains and kunlun shan and the major eustatic sea level falls of the eocene oligocene transition 34 ma and mid oligocene 30 ma which are usually held responsible for the sea retreat furthermore a concomitant and significant aridification step occurs at 36 6 ma top of chron c17n 1n as recorded by regional sedimentary records of the xining basin along the northeastern tibetan plateau suggesting that the tarim sea served as a significant moisture contributor for the asian interior

molluscan and ostracod successions from dierden s pit swanscombe insights into the fluvial history sea level record and human occupation of the hoxnian thames abstract swanscombe kent is an internationally renowned hominin site located on the south bank of the river thames east of london the swanscombe sequence has been reconstructed from exposures at several localities from which important archaeological and palaeontological assemblages have been recovered the most important of these is barnfield pit where two stone tool industries clactonian and acheulian have been recorded in superposition together with three refitting pieces of a hominin skull associated with the acheulian dierden s pit ingress vale 0 5 km to the north of barnfield pit has also yielded palaeolithic artefacts but is best known as a source of abundant non marine molluscs and as the type locality for the water vole arvicola cantiana this paper describes the molluscan and ostracod successions through the dierden s pit sequence which shed light on important aspects of the fluvial sea level and archaeological histories of the thames during mis 11 a dramatic change occurs in the molluscan record at swanscombe marked by the appearance of the rhenish suite of freshwater molluscs which has previously been used to suggest confluence of the thames and rhine systems the rhenish suite occurs in the middle gravels at barnfield pit and throughout the shell bed at dierden s pit where the component species did not appear simultaneously but colonized the thames in an ordered sequence the occurrence of the rhenish suite provides a secure basis for correlation of important archaeological horizons at swanscombe which have previously been mis correlated on the basis of artefact typology moreover it enables correlation with other mis 11 sequences some of which clacton and east hyde can be directly linked to the pollen stratigraphy of the hoxnian the ostracod succession at dierden s pit provides the first clear evidence of increasing brackish influence at swanscombe and has formed the basis for palaeoclimatic reconstructions using the mutual ostracod temperature range motr method

an analysis of eemian climate in western and central europe on the basis of 31 pollen diagrams and additional data for botanical macrofossils an analysis is made of the last interglacial eemian climatic history in western and central europe the main tool for this analysis is the climatic indicator species method only selected woody species are used for the quantification of data partial climatic range diagrams are presented for abies alba acer monspessulanum acer tataricum buxus sempervirens tilia tomentosa the problem of time correlation and pollen zonation of the eemian is discussed the climatic analysis itself is based on an improved version of the indicator species method in this version not every site is analysed for its climatic values instead maps and tables on the migrational history of hedera ilex buxus abies and species of acer tilia and abies are the basis for climatic maps showing respectively january and july isotherms for the periods of the corylus zone e4a and the carpinus zone e5 it is concluded that mean january temperatures were as much as 3 c higher at amsterdam the netherlands than at present and mean temperatures in july were 2 c higher however the thermal maximum in winter was later zone e5 than the summer thermal maximum zone e4a winter temperatures changed parallel to rise and fall of global sea level precipitation changes are more difficult to estimate in the first part of the eemian precipitation must have been relatively low but from zone e4b onward it increased to higher values reaching 800 mm and probably substantially more in zones e5 and e6 hence the eemian climate was in its beginning relatively more contintental and later from e4b onward more oceanic however as compared with the holocene the eemian climate was generally speaking more oceanic

late aptian cretaceous paleoceanography of the south atlantic ocean inferred from dinocyst communities of the sergipe basin brazil the late aptian early cretaceous is a crucial time interval for understanding the paleoceanographic changes in the southern hemisphere oceanographic changes in the emerging south atlantic ocean during this interval are reflected in the stratigraphic distribution of dinoflagellate communities recorded in the muribeca and riachuelo formations of the sergipe basin in northeastern brazil the subtilisphaera community in the lower and middle parts of the section appears to be related to the subtilisphaera ecozone and suggests the onset of tethyan influence in the central south atlantic in a restricted to inner neritic environment the succeeding spiniferites community in the middle part of the section represents the first significant transgression probably of eustatic origin the cyclonephelium exochosphaeridium community in the upper part of the section appears to be related to an oceanic event characterized by intermittent dysoxic anoxic conditions the uppermost part of the section is dominated by the spiniferites community related to a progressive regional transgression and culminating in an open marine fully tethyan environment in the central part of the widening south atlantic

dinoflagellate cyst stratigraphy of the eocene oligocene transition in central italy abstract eight dinoflagellate cyst zones based on the massignano and monte cagnero sections in central italy provide high resolution control for the eocene oligocene e o transition most of these zones have been recognized in the time equivalent contessa highway section and are calibrated against previously established magneto and biostratigraphies the invasion of the mediterranean area by several higher latitude dinoflagellate taxa marks the e o boundary as characterized by the last occurrence of the hantkeninids planktic foraminifers calibrated against a horizon just above the youngest normal polarity event within chron c1 3r quantitative and qualitative dinoflagellate events across the e o boundary allow the recognition of warmer and cooler successive intervals of sea surface temperature in addition to apparent sea level fluctuations our data indicate that latest eocene warm conditions and a sea level highstand were rapidly replaced by short term cooler conditions and a lowstand across the e o boundary horizon following a shortterm warmer interval and a highstand during the earliest oligocene a second cool and lowstand episode occurred this cool interval was of greater magnitude and duration than the one at the e o boundary horizon and may correspond to the globally recognized cooling event reported from the basal part of chron c1 3n

sedimentation rates from calcareous nannofossil and planktonic foraminifera biostratigraphy in the andaman sea northern bay of bengal and eastern arabian sea abstract in this study we determined calcareous nannofossil and planktonic foraminifera events in sediments recovered during the 2006 indian national gas hydrate program nghp expedition 01 selected bioevents permitted the assignment of orbitally calibrated ages derivative sedimentation rate estimates and identification of sedimentary discontinuities in the andaman sea at hole nghp 01 17a a late miocene to recent record was recovered but with a significant hiatus during the latest miocene and pliocene sedimentation rates here vary from 50 m myr during the pleistocene to 130 m myr for the late miocene in the northern bay of bengal at hole nghp 01 19a the base of the cored record also reaches the late miocene and extends to recent but the same hiatus missing the pliocene is present at this hole a the early pleistocene at hole nghp 1 19a shows sensible variation in sedimentation rates ranging between 130 m myr and 10 m myr during the last 0 5 ma for the late miocene the sedimentation rate was ca 50 m myr in the western bay of bengal at hole nghp 01 10b d calcareous nannofossils were sparse and only foraminifera datums are available the base of the section is latest early pliocene to late pliocene and the majority of the record is considered younger than late pliocene due to the scarcity of calcareous nannofossils and the few foraminifera datums sedimentation rates were not determined here however hole nghp 01 16a in the same region recorded the highest occurrence of pseudoemiliania lacunosa an event that confirms a pleistocene age allowing us to estimate a sedimentation rate between 110 m myr and 450 m myr along the western peninsular indian margin at hole nghp 01 01a a continuous record from the holocene to the early oligocene indicates sedimentation rates of ca 25 m myr until the middle miocene and a sensible reduction downward reaching 4 m myr in the early miocene to the early oligocene no hiatuses were observed the large changes in sedimentation rates observed in these cores reflect long timescale changes in the environment likely induced by changes in the strength of the indian monsoon system

pronounced mid pleistocene southward shift of the polar front in the atlantic sector of the southern ocean abstract ocean drilling program odp site 1094 situated in the atlantic sector of the antarctic region below the polar front pf is dominated by silica rich sediments during the pleistocene but does contain occasional calcium carbonate rich intervals the analysis of the coccolithophore assemblages of one of these intervals in the mid pleistocene allows us to interpret a prominent southward displacement of the pf an age model constructed using paleomagnetic and biostratigraphic information places this event around 1 ma close to the jaramillo subchron in an interval of strong eccentricity and high amplitude in the insolation record we distinguish five intervals based on coccolithophore assemblage and abundances according to the age model used this calcium carbonate rich period should include marine isotope stage 31 the most significant interglacial period recorded at this time however this model cannot decipher if adjacent isotope stages are partially represented interval v the oldest is interpreted as an episode with progressive abundance of coccolithophores with a characteristic assemblage from the polar front zone pfz but with dominance of siliceous micro organisms interval iv contains the maximum abundance of coccolithophores with an assemblage characteristic of the subantarctic zone saz with peaks in abundance of calcidiscus leptoporus coccolithus pelagicus helicosphaera carteri and syracosphaera spp related with the proximity of the subantarctic front saf the southward displacement of the frontal system linked to an increase in sea surface temperature produced increases in diversity and in productivity conversely we consider that the presence of some coccolithophore taxa linked in other environments with anomalies in salinity could reflect a pulse in the melting of west antarctic ice sheet as suggested previously for this interval interval iii is characterized by a pfz assemblage reflecting again a northward shift of the pf interval ii is considered in this context as another southward pulse but less important than interval iv and with the absence of saf and or melting related taxa interval i is considered a transition from a situation similar to the present day pfz to the antarctic zone conditions as consequence of a northward displacement of pf and weddell gyre antarctic circumpolar current boundary

eocene to oligocene dinoflagellate cysts from the tattofte section western external rif northwestern morocco biostratigraphy paleoenvironments and paleoclimate abstract the palynological analysis of the eocene oligocene succession from the tattofte section in the western external rif northwestern morocco reveals the presence of well preserved and diverse assemblage rich in dinoflagellate cysts dinocysts qualitative analyses especially of the dinocysts differentiate the individual stages of the deposits while quantitative analyses permit paleoenvironmental and paleoclimatic interpretations we assign the lower part of the tattofte section to the middle eocene lutetian and bartonian and its upper part to the upper oligocene chattian and define a hiatus spanning the late eocene priabonian and early oligocene rupelian the dinocyst marker events used for the biostratigraphic interpretations include the first and last occurrences of marker species such as batiacasphaera compta castellodinium compactum cerebrocysta bartonensis distatodinium biffii distatodinium paradoxum distatodinium ellipticum enneadocysta arcuata homotryblium floripes hystrichokolpoma bullatum impagidinium velorum lentinia serrata pentadinium imaginatum rhombodinium spinula saturnodinium perforatum and ynezidinium brevisulcatum as well as the chiropteridium spp acmes and we equate the chattian with the dinocyst distatodinium biffii zone of brinkhuis et al 1992 changes in the relative abundances of selected dinocyst groups spores and pollen lead to the distinction from oldest to youngest of four marine environments 1 marginal marine to coastal inner neritic under relatively warm water during the middle eocene 2 outer neritic to oceanic during a transgressive regime in the early chattian 3 fluctuating restricted to open marine in the middle chattian and 4 shallow coastal to open marine due to sea level fall at the top of the section in the latest chattian suggested by the chiropteridium spp acmes the acmes of selected thermophilic dinocyst taxa such as polysphaeridium spp and homotryblium spp suggest warm water marine conditions which may be related to the middle eocene climatic optimum meco and late oligocene warming

oligocene climate changes controlling forced regression in the eastern north sea abstract in this paper we investigate the early oligocene rupelian high angle clinoform complex from the western part of the norwegian danish basin the study consists of an integrated analysis of 3d seismics petrophysical well logs and micropaleontological data a series of erosional features and geometry of prograding units e g the high angle clinoform complex interpreted as a forced regressive unit is identified the proposed depositional model accounts for lithological variations climate induced sea level fluctuation and depositional environment the characteristic high angle clinoform complex has been estimated to be of late rupelian age paleoenvironmental reconstruction of the unit based on dinocyst analysis suggests that the deposition of the succession took place in submarine conditions presence of a cold water dinoflagellate svalbardella within the unit containing high angle clinoforms suggests that the unit was deposited during one of the oligocene glacial maxima the most probably the oi2 cooling event

neogene sapropels in the mediterranean a review for 50 years the existence of sapropels organic carbon rich sediments deposited within plio pleistocene sediments of the mediterranean sea has been known initially research concentrated on material recovered in relatively short gravity piston cores taken from the eastern basins where sequences were found to be well developed preserved and had extensive spatial coverage in the main previous studies concentrated upon establishing a workable stratigraphy spatial correlation of individual layers and determining the probable depositional mechanisms however despite a plethora of research papers some issues still remain unresolved this is in part due to a lack of agreement between investigators sampling and analytical short comings restricted sample size and the fact that in many instances like was not being compared with like recently the limit of sapropels in the western basin has been further extended as a result the palaeoceanographic palaeoclimate models which had previously been developed for deposition of sapropels in the eastern basin have been modified most recently strong links have been established between astronomical cyclicity and sapropel formation this review paper provides a summary of sapropel research to date and ongoing sapropel research in the mediterranean some of which appears in this thematic issue of marine geology it is fitting that this thematic issue of marine geology be dedicated to the memory of colette vergnaud grazzini and rob kidd who in many ways helped to initiate the resurgence in sapropel studies in the 1970s in the mediterranean perhaps in 50 more years we will know all of the answers 1999 elsevier science b v all rights reserved

tem aem observations of cl rich amphibole and biotite and possible petrologic implications cl rich amphibole and biotite 2 9 and 2 8 wt cl respectively were analyzed with high resolution transmission electron microscopy hrtem selected area electron diffraction saed and x ray emission analytical electron microscopy aem the samples are from archean granulite facies metamorphosed iron formations located in the beartooth mountains montana u s a two types of amphibole and biotite were found 1 high cl prograde hastingsite and biotite and 2 retrograde amphibole of grunerite composition containing no detectable amount of cl but intergrown with submicrometer sized slabs ofci rich annite 2 8 wt fe rich talc fe rich clinojimthompsonite and very wide chain silicate tem aem study of prograde hastingsite and biotite suggests that cl is dissolved in the crystal structures and that cl distribution is homogeneous aem analyses show that cl occupies up to about 30 and 15 of the oh positions in hastingsite and biotite respectively calculations of the cl oh exchange reaction for apatite indicate a high 10g ahoo ah o ratio of about 1 8 2 2 suggesting equilibrium with a cl rich fluid speciation and solubility modeling of the equilibrium between an aqueous fluid and the cl rich apatite biotite and hastingsite suggest that reactions with a saline brine of about 25 wt naci could explain the cl enrichment in these hydrous phases whereas the brine may coexist with an immiscible c02 dominated vapor during the granulite facies metamorphism in light of low calculated h20 activities and c02 rich fluid inclusions this explanation is consistent with the results from studies of natural and synthetic fluid inclusions and phase equilibrium experiments reported in the literature the widespread occurrence of cl rich amphibole and biotite in granulite facies rocks thus has significant implications for the nature of high grade metamorphism tem aem observations of submicrometer sized inclusions of cl rich phases within retrograde amphibole may help to explain the commonly observed heterogeneities of electron microprobe cl analyses found in samples from a variety of geologic settings microprobe analyses using typical beam diameters may sample areas with different proportions of submicroscopic intergrowths this will give apparent cl heterogeneities and fortuitous correlations between cl and concentrations of k ai and si although compositional correlations sometimes indicate reciprocal effects that are likely important for amphibole we emphasize the potential danger of artifacts resulting from submicroscopic solid inclusions additional tem aem studies on complex samples are needed to explain the compositional heterogeneities with confidence

high resolution synchrotron x ray fluorescence investigation of calcite coralloid speleothems elemental incorporation and their potential as environmental archives synchrotron high resolution and micro x ray fluorescence elemental mapping of two coeval coralloid speleothems from lamalunga cave italy are complemented with petrographic morphological and microstratigraphic studies the importance of these speleothems relies on their direct and indirect association with a complete neanderthal skeleton altamura man found inside the cave the coralloids grew discontinuously between 64 6 ka and the holocene and reveal exceptionally high concentrations of mg sr and si particularly on convex surfaces where evaporation is more intense the incorporation of trace elements depends on several factors including location shape and geometrical evolution during their growth as well as climate and environmental parameters this resulted in calcite precipitation with sr compositions from 100 to 1200 ppm and an average concentration of 7000 ppm mg an unusually high si content up to 16 is possibly derived from volcanic ash transported as particulate and in solution inside the cave the most common fabrics observed consist of non fluorescent elongated columnar calcite forming clean isopachous bands and fluorescent fibre like crystals associated with laminated lenticular bands high in sr mg and si variability in sr mg and si concentrations appears to induce fabric changes in the coralloids elongation and lattice distortion of the crystals was found to coincide with high mg concentrations the transition from compact elongated to open to fibre like is here interpreted as due to high concentrations of si and sr which are preferentially incorporated in the speleothem at crystal boundaries and intra laminae it is here inferred that coralloid fabric changes and their elemental content potentially record local rainfall variations through time with the clean compact calcite marking high infiltration and open fibre like and micrite fabrics recording dry periods

sequence biostratigraphy and paleoenvironmental reconstruction in the early eocene figols group of the tremp graus basin south central pyrenees spain the dinoflagellate cyst palynofacies and foraminiferal records from the early eocene figols group of the spanish pyrenees exhibit major changes associated with relative sea level fluctuations and variations in efficiency of the fluvial systems the mixed siliciclastic carbonate marine succession exposed in the merli esdolomada area was deposited on the shelf in a tectonically active basin under oxic conditions in shallow to moderately deep marine waters close to the lower boundary of the photic zone influenced by river discharge from adjacent emerged lands sedimentary cycles are mainly recorded by fine grained deposits the paleoenvironmental interpretation of palynological and calcareous microfaunal records allows the definition of depositional sequences and enables to trace basinward surfaces identified in more proximal settings by means of sedimentological facies analysis at the same time the solid regional stratigraphic framework already available for the figols group allows new insights on the paleoecology of extinct taxa the merli esdolomada section me spans two 3rd order sequences the upper sequence reflects more marginal marine conditions than the lower one thus pointing to an overall shallowing trend with time in the lower sequence the maximum flooding interval is characterised by a rich and diverse microfauna highest relative abundances of marine phytoplankton and typically neritic dinoflagellate cyst dinocyst assemblages dominated by spiniferites and cordosphaeridium the final phase of the highstand systems tract in proximity of the main sequence boundary is characterised by a decrease in abundance and diversity of dinocysts with the dominance of the lagoonal genus polysphaeridium and by decreased microfaunal diversity discorbids miliolids larger foraminifers palynological records permit the reconstruction of activation and deactivation phases of the fluvial systems variations in runoff from the hinterland nutrient delivery to the sea and productivity in surface waters of the tremp graus basin the overall abundance of spiniferites and the scarcity of peridinioid cysts lingulodinium pediastrum and botryococcus algae are interpreted to indicate oligotrophic conditions during the deposition of the investigated succession recurrent intervals where the temporary disappearance of spiniferites corresponds to highest relative abundances of operculodinium and herbaceous debris are the main evidence for river plumes and denote periods of enhanced fluvial discharge reflecting a milankovitch type cyclicity the rotalia group which shows abundance peaks of cuvillierina spp in the shallower intervals is often associated with these episodes thus suggesting for this taxon more tolerance to turbidity than larger foraminifera within the maximum flooding zone a thalassiphora patula acme corresponding to the local disappearance of homotryblium is deemed to record the distal expression of a fluvial activation which triggered water salinity stratification despite broad morphological similarities homotryblium exhibits more cosmopolitan preferences than polysphaeridium which is instead confirmed as a lagoonal euryhaline taxon the increase of spinizonocolpites pollen toward the top of the figols group records the northwestward migration of nypa mangrove palms from southern europe during the mid early eocene

environmental forcings of paleogene southern ocean dinoflagellate biogeography 1 despite warm polar climates and low meridional temperature gradients a number of different high latitude plankton assemblages were to varying extents dominated by endemic species during most of the paleogene to better understand the evolution of paleogene plankton endemism in the high southern latitudes we investigate the spatiotemporal distribution of the fossil remains of dinoflagellates i e organic walled cysts dinocysts and their response to changes in regional sea surface temperature sst we show that paleocene and early eocene 65 50 ma southern ocean dinocyst assemblages were largely cosmopolitan in nature but that a distinct switch from cosmopolitan dominated to endemic dominated assemblages the so called transantarctic flora occurred around the early middle eocene boundary 50 ma the spatial distribution and relative abundance patterns of this transantarctic flora correspond well with surface water circulation patterns as reconstructed through general circulation model experiments throughout the eocene we quantitatively compare dinocyst assemblages with previously published tex86 based sst reconstructions through the early and middle eocene from a key locality in the southwest pacific ocean odp leg 189 site 1172 on the east tasman plateau we conclude that the middle eocene onset of the proliferation of the transantarctic flora is not linearly correlated with regional sst records and that only after the transantarctic flora became fully established later in the middle eocene possibly triggered by large scale changes in surface ocean nutrient availability were abundances of endemic dinocysts modulated by regional sst variations

late glacial holocene paleoclimatic and paleoceanographic evolution of the aegean sea micropaleontological and stable isotopic evidence abstract late glacial to holocene paleoclimatic and paleoceanographic changes are examined using records of calcareous and organic walled marine microfossils pollen and terrestrial spores and oxygen isotope data in cores from the aegean sea basins planktic foraminiferal coccolith and dinoflagellate data show that the late glacial holocene transition in the region was associated with a large warming of surface water mediterranean based paleotransfer functions for planktic foraminifera show a 5 10 c increase in surface water temperature from 14 000 to 9600 yr b p estimates of surface water oxygen isotopic composition 18 o w derived from planktic foraminiferal oxygen isotopic and transfer function data indicate that this warming was associated with a 2 0 to 2 5 reduction in 18 o w transfer function results indicate corresponding 1 0 to 1 5 salinity reductions for this tim ca 6400 9600 yr b p throughout the aegean sea pollen dinoflagellate and isotopic data show that the early holocene excess fresh water originated from rapid melting of the northern european and siberian ice sheets supplied primarily from the black sea by the opening of bosphorus and dardanelles channels during the post glacial sea level rise and supplemented by major rivers entering the aegean sea continuous outflow of fresh water into the aegean sea provided a low salinity surface lid preventing the ventilation of the deep water benthic foraminifera shows a major turn over that indicates low dissolved oxygen however bottom waters were not anoxic sapropel level s1 resulted from a combination of stagnant deep water in isolated depressions increased terrigenous organic matter and periods of high primary productivity as indicated by pollen and dinocysts respectively the surface water temperature and salinity reached present day values at 6400 yr b p with little subsequent change despite the major deforestation onshore

the morphology of the top tertiary erosion surface in the belgian sector of the north sea abstract the detailed analysis of more than 12 000 km of high resolution reflection seismic profiles has shed some new light on the morphology of the erosion surface at the top of the tertiary substratum in the belgian and northern french sectors of the north sea this morphology seems to be slightly controlled by the lithology and structure of the tertiary substratum some remarkable planation surfaces paleovalleys and other morphological features have been identified the main planation surfaces are well defined and subject to later chronostratigraphical control might yield a clue to the record of late pleistocene postglacial sea level rises in the southern north sea basin the paleovalleys seem to represent the hitherto missing link between onshore paleovalley systems and the axial paleochannel in the southern bight

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

ocean atmosphere responses to climatic change in the labrador sea pleistocene plankton and pollen records abstract pleistocene climate change is examined using proxy climatic records from oxygen isotope data calcareous and organic walled marine microfossils pollen and terrestrial spores deposited during the past 0 9 ma at odp site 646 in the labrador sea 500 km north of the present polar front paleotransfer functions applied to planktonic foraminiferal assemblages show relative increases in interglacial summer 3 7 and winter 3 5 temperatures and in winter salinity 0 5 2 for the past 0 4 ma but only two earlier intervals early stage 11 and stage 17 have changes of comparable magnitude coccolith and dinoflagellate cyst accumulation rates show that primary productivity is generally correlated with temperature and salinity changes at the start of interglacials these productivity peaks lag the ice volume changes by 2 4 ka dinocyst blooms seem to precede coccolith peaks reflecting the tolerance of opportunistic species for large variations in temperature and salinity peaks in pollen and spore abundance are strongly correlated with ice volume which controls the position and stability of the polar jet stream in addition to the northern extent of forest vegetation time series analysis was made of 7 oceanographic variables sst summer and winter surface salinity coccoliths dinocysts planktonic and benthic foraminifera and 5 other variables 18 pollen spores percent sand foraminiferal test fragmentation and reworked palynomorphs most variables showed significant power peaks at 100 ka and or at 41 ka however sea surface responses showed minor peaks at 26 and 16 ka and microfossil productivity also showed significant peaks at 68 ka the high latitude labrador sea records thus display large non linear regional responses to climate changes in addition to the effects of orbital insolation forcing at 41 and 23 ka

rainy periods and bottom water stagnation initiating brine accumulation and metal concentrations 1 the late quaternary a working hypothesis is proposed to account for the present accumulation of brines in isolated pockets of the ocean floor and for the formation of the underlying organic and metal rich sediments these are the tyro and bannock basins in the east mediterranean the red sea deeps and the orca basin in the northern gulf of mexico initiation of brine derived deposition in the red sea deeps and orca basin occurred between 12 000 and 8000 years b p this time bracket also encompasses the formation of the latest east mediterranean sapropel and the wettest global climate since the last glacial maximum this wet period first appeared in the tropics around 12 000 years b p then in the subtropical and middle latitudes during the same period the 23 000 year precession cycle brought the summer insolation of the northern hemisphere to its peak at 11 000 years b p with retreating northern hemisphere ice sheets the red sea deeps and the orca basin became anoxic during this humid period and metal rich sapropel deposition then began in contrast the tyro and bannock basins began accumulating a brine long before and persisted beyond this climatic stage the hypothesis involves two propositions 1 as in the eastern mediterranean sea marine anoxia was mainly the consequence of the large influx of continental runoff and local precipitation longer residence time of bottom waters so called stagnation in silled rimmed basins would have resulted from lower salinity at the sea surface in areas of deep water formation in the eastern mediterranean the red sea and the gulf of mexico and 2 miocene or older evaporites underlie these basins or outcrop on their flanks leaching from these evaporites was an ongoing process before the quasi stagnation phase but the initial leachate much less saline than the present brines was continuously flushed by bottom circulation the climate induced quiescence of bottom waters in these basins enabled the leachate to accumulate the feedback of stagnation by increased density progressively raised the salinity of entrapped bottom waters to the present brine concentration the high density has resisted brine removal by bottom circulation until present time long after cessation of the initiating wet period the brines therefore are stagnant fossil waters

evolution of the lian river coastal basin in response to quaternary marine transgressions in southeast china abstract the coastal basin deposit in the lian river plain is among the thickest quaternary sequences along the southeastern coast of china the clastic sediment accumulated in a variety of environmental settings including fluvial channel estuary coastal and marine conditions detailed investigation of lithofacies grain size distributions magnetic susceptibility microfossils and chronology of marine core cn01 compared with regional cores and combined with offshore seismic reflection profiles has allowed us to correlate the spatial stratigraphy in the inner and outer plain and the seismic units grain size distribution analysis of core cn 01 through compositional data analysis and multivariate statistics were applied to clastic sedimentary facies and sedimentary cycles results show that these methods are able to derive a robust proxy information for the depositional environment of the lian river plain we have also been able to reconstruct deltaic evolution in response to marine transgressions on the basis of dating results and chronostratigraphy the estimated age of the onset of deposition in the lian river coastal plain was more than 260 kyr bp three transgressive sedimentary cycles revealed in many regional cores support this age model detailed lithological and microfossil studies confirm that three marine m3 m2 and m1 and three terrestrial t3 t2 and t1 units can be distinguished spatial correlation between the inner plain outer plain typical cores characterized by marine transgression cycles and offshore seismic reflectors reveals coherent sedimentary sequences two major boundaries unconformity and erosion surfaces can be recognized in the seismic profiles and these correspond to weathered reddish and or variegated clay in the study core suggesting that quaternary sediment changes on the lian river plain were largely controlled by sea level variations and coastline shift during glacial interglacial cycles

cretaceous anoxic oxic changes in the moldavids carpathians romania abstract this study focused on the cretaceous black shale successions followed by red shales that crop out at the outer regions of the romanian carpathians in the moldavids the oldest parts of the black shale units deposited in an abyssal plain during late valanginian late barremian time they are mainly characterized by hemipelagic and pelagic muddy siliciclastic rocks and carbonates commonly intercalated with fine grained turbidites during the sedimentation of the middle part of the black shale units in the late barremian early albian interval the depth of the basin increased as the carbonate hemipelagic sedimentation was replaced by a mainly siliceous one only a few thin turbidite intercalations are present the youngest part albian pro parte of the black shale units is characterized by a turbiditic sedimentation with mainly sandy sequences of middle and lower deep water fans we may assume that the depth of the basin continuously decreased the presence of authigenic glauconite in the albian sandstones suggests a palaeoenvironmental change linked to the occurrence of oxygenated turbidity current circulation a significant shift in the sedimentation regime in the eastern carpathian moldavids took place in the late albian when cretaceous oceanic red beds corb occurred this type of sedimentation lasted up to the coniacian the lower part of the corbs that contains radiolarites intercalated with variegated shales pyroclastic tuffs and thin sandstones is interpreted as a hemipelagic and pelagic sedimentation in the abyssal plain environment where rarely turbidites occurred upwards there are mainly burrowed variegated red and green shales the youngest parts of corbs are characterized by increased thickness and frequency of the turbidites while the main part of the corb is carbonate free or has very low carbonate content the upper part of these strata becomes rich in marl and mudstone strata indicating a decrease of the basin depth the accumulation of black shales in the eastern carpathians during the late valanginian late albian interval is linked to the existence of a small silled basin of the moldavian trough in which restricted circulation led to the density stratification of the water column resulting in the deposition of anoxic lower cretaceous sediments i e the black shales because of the tectonic deformation that took place within the lower upper cretaceous boundary interval the restricted circulation had changed to an open circulation regime in the moldavian trough hence the anoxic regime was progressively replaced by an oxic one across the albian cenomanian boundary interval the beginning and the end of the corbs in the moldavid units depend thus on various palaeogeographic and palaeoenvironmental settings and it was controlled by the regional tectonic activity

sea level during the penultimate interglacial period based on a submerged stalagmite from argentarola cave italy accurate constraints are presented for the absolute age duration and sea level for the highstand corresponding to marine isotope stage mis 7 1 our work is based on a stalagmite collected in a currently submerged cave from italy argentarola cave flooding of this coastal cave is clearly marked within the stalagmite by a thick marine overgrowth of serpulid worms precise uranium thorium u th ages measured by thermal ionization mass spectrometry suggest that the stalagmite growth varied in phase with climate during mis 7 2 and mis 6 the penultimate glacial period in addition the period of marine transgression is bracketed between 202 and 190 kyr bp defining a mis 7 1 duration of 11 2 kyr comparison with previous studies provides a new constraint on the sea level during mis 7 1 that has approximately remained between 318 and 39 m relative to present sea level the timing of the mis 7 1 highstand is in full agreement with the specmap chronology which contrasts with the growing body of evidence showing a significant phase difference for mis 5 5 a tempting conclusion is that second order sea level highstands such as mis 7 1 may be purely driven by astronomical changes in contrast with major terminations such as termination ii atmospheric co2 levels may partly explain this contrast since the two sea level transitions mis 7 2 7 1 and mis 6 5 5 are characterized by very different co2 rises 20 vs 100 ppm fl 2002 elsevier science b v all rights reserved

timing of massive fleuve manche discharges over the last 350 kyr insights into the european ice sheet oscillations and the european drainage network from mis 10 to 2 continuous high resolution mass accumulation rates mar and x ray fluorescence xrf measurements from marine sediment records in the bay of biscay ne atlantic have allowed the determination of the timing and the amplitude of the fleuve manche channel river discharges during glacial stages mis 10 mis 8 mis 6 and mis 4 2 these results have yielded detailed insight into the middle and late pleistocene glaciations in europe and the drainage network of the western and central european rivers over the last 350 kyr this study provides clear evidence that the fleuve manche connected the southern north sea basin with the bay of biscay during each glacial period and reveals that fleuve manche activity during the glaciations mis 10 and mis 8 was significantly less than during mis 6 and mis 2 we correlate the significant fleuve manche activity detected during mis 6 and mis 2 with the extensive saalian drenthe substage and the weichselian glaciations respectively confirming that the major elsterian glaciation precedes the glacial mis 10 in detail massive fleuve manche discharges occurred at ca 155 ka mid mis 6 and during termination i while no significant discharges are found during termination ii it is assumed that a substantial retreat of the european ice sheet at ca 155 kyr followed by the formation of ice free conditions between the british isles and scandinavia until termination ii allowed meltwater to flow northwards through the north sea basin during the second part of the mis 6 we assume that this glacial pattern corresponds to the warthe substage glacial maximum therefore indicating that the data presented here equates to the drenthe and the warthe glacial advances at ca 175 160 ka and ca 150 140 ka respectively finally the correlation of our records with odp site 980 reveals that massive fleuve manche discharges related to partial or complete melting of the european ice masses were synchronous with strong decreases in both the rate of deep water formation and the strength of the atlantic thermohaline circulation fleuve manche discharges over the last 350 kyr probably participated with other meltwater sources in the collapse of the thermohaline circulation by freshening the northern atlantic surface water

an integrated environment analysis lithofacies chemofacies biofacies of the oligocene calcareous siliciclastic shelf deposits in northern germany during the oligocene monotonous fine grained siliciclastic and calcareous shelf sediments of the septaria clay fm were deposited in the north german basin the uniform grain size spectrum and the homogeneous outward appearance of these sediments forces environmental analysis to be based on a joint investigation of the inorganic and organic facies the transgression of the rupelian sea caused tidal sand sheets to form off the mouth of estuaries upon deepening of the basin the benthonic oxygen content of the bottom water diminished and inner shelf muds were deposited following this early transgression a conspicuous change may be recognized when a siliciclastic shelf was replaced by a calcareous siliciclastic shelf upon shoaling of the basin and warming of the seawater these outer shelf conditions persisted until fine grained clastic sediments became more and more dominant during the early late oligocene their depositional environment may be described as shallow lagoon in the succeeding formation of the oligocene tidal bars and estuarine sands are characteristic the uppermost formation penetrated by the drill hole in the gartow area contains estuarine channel sands in conclusion the oligocene sedimentary record reflects a symmetrical facies pattern showing calcareous siliciclastic cyclothems in the central section and siliciclastic shelf deposits below and above reflecting the cyclical nature of the oligocene sea in a dominantly tidally influenced depositional environment the use of clay minerals heavy minerals carbonates phosphates and sulphides together with dinocysts nannofossils and foraminifera has proved to be a successful tool in palaeoecological and palaeoenvironmental analyses

incised palaeo channels of the late middle pleistocene thames age origins and implications for fluvial palaeogeography and sea level reconstruction in the southern north sea basin abstract multidisciplinary investigations of the infills of steeply incised buried channels on the coast of essex england provide important insights into late middle pleistocene climate and sea level change and have a direct bearing on the differentiation of mis 11 and mis 9 in terrestrial records new data are presented from rochford and burnham on crouch where remnants of two substantial palaeo channels filled with interglacial sediment can be directly related to the terrace stratigraphy of the thames the sediments in both channels accumulated in an estuarine environment early in an interglacial when mixed oak forest was becoming established lithological evidence suggests that the interglacial beds post date the brackish water infill of an older palaeo channel ascribed to the hoxnian and correlated with part of mis 11 and pre date terrace gravels barling gravel ascribed to mis 8 an mis 9 attribution is supported by molluscan biostratigraphy palaeo salinity and amino acid racemization data the relative sea level record in this area thus includes evidence for two major marine transgressions during mis 11 and mis 9 with local maxima of 10 m o d both are associated with sediments that show hoxnian palynological affinities the wider significance of these findings and of an intermediate phase of pronounced fluvial incision during mis 10 is discussed

incised pleistocene valleys in the western belgium coastal plain age origins and implications for the evolution of the southern north sea basin abstract the belgian coastal plain occupies a key position as it is located at the transition between the southern north sea basin and the strait of dover it is characterized by thick sequences 20 m of pleistocene terrestrial and littoral sediments yet the wider stratigraphical and palaeo environmental significance of these sediments received little attention in this paper we draw on the results of a recent sedimentological study based on 100 drillings that spans the pleistocene sequence and present new biostratigraphical pollen foraminifera ostracods data all revealing a complex history of deposition the record includes evidence of the development of incised valley systems that were initiated in the late middle and late pleistocene five phases of fluvial incision can be identified the majority of the infills are deposited in an estuarine environment that passes into a fluvial environment land inward except the weichselian infill which has a predominant fluvial origin the greatest part of the most seaward located zone of the western coastal plain was free of valley incisions there shallow marine sediments built up the record local biostratigraphical investigations provide a timeframe the result is placed in a regional context

the late middle pleistocene biostratigraphy of the thames valley england new data from eastern essex abstract coring investigations at east hyde near tillingham essex have revealed a sequence of fluvial and estuarine deposits infilling a channel incised into london clay these deposits are of thames origin and were deposited after the river s diversion into eastern essex late in the anglian stage the detailed litho and biostratigraphy of the deposits are described ostracod and molluscan data confirm that the lower parts of the sequence accumulated in a quiet fluvial environment rich in aquatic vegetation the upper sediments accumulated in an inner estuarine environment under conditions of rising sea level pollen assemblages from both units show strong biostratigraphical affinities with the hoxnian stage particularly with the hoxnian late temperate substage ho iii the sequence has also yielded a rare assemblage of freshwater fluvial molluscs the rhenish fauna which migrated into the thames following a link with the rivers of continental europe the occurrence of theodoxus serratiliniformis is exceptionally rare representing only the second record of the species in the entire british pleistocene the molluscan assemblages show striking similarities with those at clacton in northeast essex and swanscombe kent and provide strong evidence that the three sites are contemporaneous and were connected in the same fluvial system the timing of the migration of the rhenish fauna into britain and the implications for sea level reconstruction in the southern north sea region are discussed the episode of major climatic warmth and high eustatic sea level represented at east hyde is correlated with stage 11 of the deep sea record

glacial eustasy during the cenozoic sequence stratigraphic implications a newly constructed composite oxygen isotope record is a proxy for eustasy that extends back to the cretaceous tertiary boundary and provides an independent test of sequence stratigraphic based eustatic curves the isotope record shows several eustatic episodes that are consistent with the geological record of ice sheet evolution the first evidence for the existence of an ice sheet in east antarctica occurs near the lower middle eocene boundary base of the lutetian stage there is no evidence for a large ice sheet on antarctica prior to this time however strata of this age are lacking over most of the continent the isotope curve also indicates that the ice sheet experienced phases of growth during the late eocene and middle oligocene followed by a decrease in volume in the early miocene the ross sea stratigraphic record indicates initial evolution of the west antarctica ice sheet during the early miocene by the middle miocene the ice sheet spread across the ross sea weddell sea and antarctic peninsula continental shelves the pliocene pleistocene record of glaciation in antarctica includes numerous glacial erosion surfaces on the continental shelf indicating repeated advance and retreat of both east and west antarctica ice sheets these volume changes in the antarctica ice sheet were in response to the rise and fall of sea level caused by expanding and contracting northern hemisphere ice sheets there is a reasonable correlation between eustatic curves derived from sequence stratigraphic studies and the composite oxygen isotope record since the middle eocene this correlation indicates that glacial eustasy has been the principal factor regulating stratal stacking patterns on a global scale since the middle eocene

pleistocene rhine thames landscapes geological background for hominin occupation of the southern north sea region this paper links research questions in quaternary geology with those in palaeolithic archaeology a detailed geological reconstruction of the netherlands south west offshore area provides a stratigraphical context for archaeological and palaeontological finds progressive environmental developments have left a strong imprint on the area s palaeolithic record we highlight aspects of landscape evolution and related taphonomical changes visualized in maps for critical periods of the pleistocene in the wider southern north sea region the middle pleistocene record is divided into two palaeogeographical stages the pre anglian elsterian stage during which a wide land bridge existed between england and belgium even during marine highstands and the anglian elsterian to saalian interglacial with a narrower land bridge lowered by proglacial erosion but not yet fully eroded the late pleistocene landscape was very different with the land bridge fully dissected by an axial rhine thames valley eroded deep enough to fully connect the english channel and the north sea during periods of highstand this tripartite staging implies great differences in i possible migration routes of herds of herbivores as well as hominins preying upon them ii the erosion base of axial and tributary rivers causing an increase in the availability of flint raw materials and iii conditions for loess accumulation in northern france and belgium and the resulting preservation of middle palaeolithic sites 2011 john wiley sons ltd

middle pleistocene lacustrine deposits in eastern essex england and their palaeogeographical implications investigations in quarry exposures in the asheldham gravel and related deposits of southeast essex are described section logging mapping and borehole investigations are supported by clast lithological heavy and clay mineralogical determinations the sediments are derived from reworking of local thames basin materials fine sediment being predominantly from the london clay the sequence is shown to represent an aggradation that began as the fluvial infilling of the river medway valley the river thames diverted into this valley by glaciation further west overwhelmed the medway reworking the deposits the valley was subsequently drowned and fine laminated lake sediment was initially deposited this was during a period when the valley was drowned by the glacial lake ponded in the southern north sea basin by the anglian elsterian ice sheet progradation by a braid delta complex advanced along the valley and subsequently fluvial deposition returned valley widening and straightening accompanied the delta progradation the deposits were dissected by deep fluvial valleys infilled by hoxnian interglacial sediments the asheldham gravel is therefore placed in the anglian elsterian stage

sea level and surface water change in the western north atlantic across the oligocene miocene transition a palynological perspective from iodp site u1406 newfoundland margin abstract the oligocene miocene transition omt 23 1 ma terminates the late oligocene warming trend and is marked by a transient large amplitude expansion of antarctic ice sheets the associated glacial maximum which is expressed by a 1 positive shift in benthic foraminiferal oxygen isotope values is commonly referred to as the mi 1 isotope event whereas the causes for the glacial maximum at the omt are intrinsically connected to southern hemisphere ice sheet dynamics the behavior of the surface ocean in the northern hemisphere during this time is poorly known to contribute to a better understanding of the paleoceanographic evolution during the omt in the higher latitude north atlantic we have analysed both marine and terrestrial palynomorphs from integrated ocean drilling program iodp site u1406 offshore newfoundland this site has yielded a complete omt section and exhibits a high quality magnetostratigraphy that provides precise age control and allows reliable correlation to other records beyond newfoundland our palynological data which span the interval from 23 3 to 22 5 ma and have a mean temporal resolution of 11 9 kyrs show strong 110 kyr eccentricity paced oscillations during the earliest miocene these oscillations are in phase with similar cyclicity identified in previously published benthic foraminiferal oxygen isotope records more specifically a pronounced sea level variability is documented by the abundances of neritic dinoflagellate cysts dinocysts and terrigenous palynomorphs which both reach maxima during peak glacial intervals as inferred from previously published south atlantic benthic oxygen isotope data a decline in the abundance of warmer water dinocysts suggests a surface water cooling offshore newfoundland from the latest oligocene onwards surface water productivity as derived from the ratio between heterotrophic and autotrophic dinocysts remained generally low throughout the studied interval notably this ratio does not exhibit any correlation with changes in surface water temperature which is estimated from the ratio of warm water over cold water dinocysts together with the consistently low surface water productivity the lack of a correlation between surface water productivity and temperature makes it highly unlikely that the observed paleoceanographic change was caused by a southward migration of the arctic front instead we argue that our data may document an enhanced influence of the proto labrador current on surface waters offshore newfoundland during the earliest miocene that suppressed the influence of the gulf stream in this region of the northwest atlantic we speculate that the enhanced influence of the proto labrador current was triggered by cooling of the northern hemisphere and possibly modulated by high latitude sea ice expansion

shoreface sand supply and mid to late holocene aeolian dune formation on the storm dominated macrotidal coast of the southern north sea abstract although pulses of coastal dune development in the course of the holocene have been attributed to variations in the availability of sand to modulation of sand supply by sea level change and to changes in wind conditions identifying the processes driving such pulses has been rather elusive the shore deposits bordering the tide and storm wave dominated southern north sea evince complex mid to late holocene stratigraphy and sediment heterogeneity these deposits include a unique 7 km long 0 3 0 6 km wide and up to 7 m high aeolian sand unit the ghyvelde dune occurring astride the french belgian border in an apparently anomalous inland location the dune overlies and is surrounded by tidal sandy and muddy deposits incorporating freshwater peat data from four mechanical cores and eight auger holes and three radiocarbon ages and one osl age suggest that this inland dune was part of an ancestral north sea sand flat and mudflat environment confronting the dune stratigraphy with the prevailing tide and storm controlled dynamics of shoreline progradation in this area indicates that dune formation occurred under a pulse of abundant sand supply resulting from the attachment to a mid holocene north sea tidal flat shore of a shoreface tidal bank under repeated storms this mode of onshore sand supply generates extremely rapid progradation up to 1 km over a century of the sand flat shore the surface of which serves as a large aeolian fetch zone for active backshore dune accumulation while parts of this surface trap locally significant amounts of mud that are subsequently fossilised by aeolian sand the potential influence of sea level and storminess in modulating the timing of shoreface sand supply and late holocene coastal dune development in the southern north sea reported in studies from other areas remains to be established

reconstruction of short term palaeoceanographic changes during the formation of the late albian niveau breistroffer black shales oceanic anoxic event 1d se france the niveau breistroffer black shale succession in the vocontian basin se france is the regional equivalent of the widely distributed late albian oceanic anoxic event 1d the studied black shale rich interval at the col de palluel section is 6 28 m thick and comprises four black shale units with up to 2 5 wt total organic carbon toc intercalated with marlstones calcareous nannofossil palynomorph planktic foraminifera and stable isotopic data from the niveau breistroffer succession suggest that short term climate changes influenced its deposition with relatively warm and humid climate during black shale formation in comparison with relatively cool and dry climatic conditions during marlstone deposition an increase in the terrigenous marine ratio of palynomorphs indicates enhanced humidity and higher runoff during black shale formation a nutrient index based on calcareous nannofossils and the abundance pattern of small 63 125 m hedbergellid foraminifera show short term changes in the productivity of the surface water surface water productivity was reduced during black shale formation and increased during marlstone deposition a calcareous nannofossil temperature index and bulk rock oxygen isotope data indicate relative temperature changes with warmer surface waters for black shale samples at these times warm humid climate and reduced surface water productivity were accompanied by greater abundances of subsurface dwelling calcareous nannofossils nannoconids and planktic foraminifera rotaliporids these taxa presumably indicate more stratified surface water conditions we suggest that the formation of the niveau breistroffer black shales occurred during orbitally induced increase in monsoonal activity that led to increasing humidity during periods of black shale formation this in turn caused a decrease in low latitude deep water formation and probably an increase in surface water stratification the combination of these two mechanisms caused depleted o 2 concentrations in the bottom water that increased the preservation potential of organic matter

middle to late miocene caribbean dinoflagellate assemblages and palynofacies dsdp leg 15 site 153 abstract changes in oceanic circulation and productivity patterns near central america have been explained using numerous different tools such as tectonics geochemistry and micropaleontology this paper aims to contribute to this discussion through the study of dinoflagellates and palynofacies in the drill core from dsdp site 153 based on foraminiferal data the studied section is divided into the middle and upper miocene and our dinoflagellate events also support an age model of 15 to 8 ma indval ecological indexes and the p g dinoflagellate ratios were used to develop paleoenvironmental inferences the indicator species are operculodinium centrocarpum and tectatodinium pellitum for the mm1 interval spiniferites spp and impagidinium strialatum for mm2 and selenopemphix armageddonensis lejeunecysta spp and l tenella for um3 intervals mm1 and mm2 are characterized by a dominance of gonyaulacoids and inner to outer neritic environments the um3 interval is interpreted as an outer neritic environment in the base middle portion and inner neritic in the uppermost part with a shift from gonyaulacoid to peridinioid dominance suggesting an increase in productivity during the middle miocene productivity is low due to intermittent marine circulation restrictions in the caribbean sea and there is a slight increase during the upper miocene following reestablishment of the global oceanic circulation this is directly connected to the occurrence of geotectonic and paleoceanographic events in the region during the miocene mainly by mass movements such as the panama gateway and the opening of the pedro channel to the north changing the surface conditions in the caribbean sea

thermoluminescence dating of the holsteinian marine formation of herzeele northern france thermoluminescence dating of potassium feldspar coarse grains from the fossiliferous holsteinian marine formation of herzeele at the southern limit of the north sea basin yields a minimum age of 228 30 ka a tentative correction for the long term fading of the tl signal in potassium feldspar is proposed assuming a lifetime of 711 ka this correction would yield a preliminary age estimate of 271 36 ka these results support a minimum oxygen isotope stage 7 age but do not preclude at this stage of our research a possible correlation with late oxygen isotope stage 9 these results are in agreement within the error of the method with independent absolute dates u th and esr obtained on in situ marine shells which range from 225 ka to 348 ka this study provides evidence of the reliability of tl age estimates on potassium feldspar coarse grains from shallow marine sediments older than the last interglacial