middle and late jurassic radiolarian palaeoecology versus carbon isotope stratigraphy abstract jurassic radiolarians are sensitive to palaeoclimatic palaeoceanographic changes recorded by the stable carbon isotope curve carbon isotopic variations have been linked to changes in ocean structure productivity and concentrations of greenhouse gases in the atmosphere in the middle upper jurassic terminilletto section of the umbria marche sabina apennines central italy well preserved radiolarians are present in a sequence of cherty limestones interbedded with platform derived carbonates the 13 c curve in the aalenian kimmeridgian interval indicates three main positive 13 c events in the lower bajocian late bathonian lower callovian and middle oxfordian the positive 13 c shifts are correlated to increases in visible chert in the outcrop and may represent periods of increased biological productivity of surface sea water spumellaria nassellaria ratios and the fluctuations of relative abundance of selected genera tend to correlate with 13 c and chert abundance values and seem to be related to episodes of high nutrient mobilisation from the base of the bajocian the radiolarian associations show a slight tendency towards diversification coincident with increasing 13 c values in the upper part of the middle bajocian last appearances prevail over first appearances associated with the peak of the 13 c event this may indicate maximum eutrophic conditions coincident with the late bathonian early callovian positive 13 c shift the radiolarian associations record a different trend with respect to the bajocian event when the 13 c values are increasing to a maximum radiolarian associations tend to be reduced in species diversity followed by a small diversification trend when the 13 c values are decreasing we speculate that during the callovian a more stressful palaeoenvironment due to high level of eutrophication is indicated by the combination of high productivity of biogenic silica and low carbonate input although varying preservational conditions may have influenced the observed trends in the radiolarian associations the good correlation between changes of sedimentation patterns radiolarian assemblages and 13 c positive anomalies open interesting avenues for further investigations concerning the palaeoecology of mesozoic radiolarians

introduction to albertosaurus special issue this special issue is being published to mark the passage of a century since barnum brown made a remarkable discovery in the badlands of alberta brown was from the american museum of natural history amnh in new york and he had come to alberta the previous year 1909 to check a report of dinosaur bones near the present day town of drumheller he had been impressed enough to mount an expedition that set off in a flat bottomed scow down the red deer river on august 3 1910 as they floated downstream they frequently stopped and looked for fossils in the badlands on august 11th they found what they thought was much of an albertosaurus skeleton in hard rock they realized by the next day however that they were in fact excavating the well preserved bones of several individuals in his fieldnotes brown s assistant peter kaisen noted that the whole top of a hill is nothing but a mass of bone there are four hind feet in sight vertebrae and a lot of limb bones on september 4th they loaded eight boxes of bones the product of 29 man days spent in the bonebed on the scow and floated the expedition farther downstream the specimens were shipped to new york where they were prepared put on display for a short time and then mostly forgotten although brown occasionally mentioned the 1910 discovery in papers brown 1914 matthew and brown 1923 and

lack of organic matter accumulation on the upwelling influenced somalia margin in a glacial interglacial transition abstract monsoon induced upwelling has been operating off somalia for at least the last 160 000 years making the nw indian ocean one of the most productive oceanic areas in the world we have studied the sediments recovered during the indusom cruise of the r v marion dufresne from three different environments off this margin a core from the highly productive surface waters core md85 674 a core where the oxygen minimum intersects the slope core md85 664 and a reference core from the deep basin with normal bottom oxygen levels and moderate primary production core md85 668 though the first two environments are a priori favourable to organic matter om accumulation no marine om enrichment can be observed in the cores to understand this anomaly emphasis is placed upon the transition from isotopic stage 6 to stage 5 because the end of the glacial stage 6 is characterised by intensified upwelling and primary productivity in this region whereas stage 5 experienced a marked decrease in productivity various palaeoenvironmental markers such as om v ni cu zn ba and p have been used to identify periods of high productivity and or bottom water oxygen depletion the results suggest that 1 the lack of marine om in two settings favourable to organic carbon storage may be due to the nature of primary productivity coccolithophorid production would not be prone to om accumulation in contrast to the contribution of om by diatoms or particularly naked phytoplankton dinoflagellates or other peridinians 2 ba is not an accurate palaeoproductivity marker in this region although the oceanic environment would have been a priori suitable for the use of ba as a proxy indicator 3 the period of intensified upwelling in stage 6 as well as the stage 6 5 transition left no geochemical imprint on the sediments this means that some upwelling systems may not be accompanied by marked enrichments in marine organic matter within the underlying sediments in other words the somalia upwelling does not participate to the so called biological pump and has no positive effect upon long term carbon storage

late barremian early aptian dark facies of the subbetic betic cordillera southern spain calcareous nannofossil quantitative analyses chemostratigraphy and palaeoceanographic reconstructions abstract in order to determine the driving mechanism behind the deposition of the aptian dark facies in the pelagic subbetic basin southern spain two latest barremian early aptian complementary sections embracing the oceanic anoxic event 1a were selected for a multidisciplinary study quantitative and statistical analyses of calcareous nannofossil assemblages are complemented with planktonic foraminifera radiolaria and geochemical data c and o isotopes and biomarkers the results indicate that most of the latest barremian was characterized by oligotrophic conditions with a low nutricline and neritic influence which were interrupted by short lived episodes of mesotrophic surface waters in contrast broadly meso eutrophic surface waters with a high nutricline and a probable development of water stratification are inferred for most of the early aptian it is suggested that an increased runoff as a consequence of a more humid climate in the adjacent continental area caused this fertilization neritic dwellers such as nannoconids and pentaliths experienced a drastic decrease in abundance as the result of the combined effects of a biocalcification crisis nannoconid crisis and the deepening of the basin high productivity and enhanced surface water stratification favoured low oxygen content in the bottom waters increasing organic matter preservation a reduction in surface water fertility and a shift towards generally cooler conditions occurred during the late early aptian it is postulated that a cooler and drier climate leads to a reduction in runoff and decreased nutrient flux into the basin the obtained results suggest that the formation of the aptian dark facies was mainly controlled by enhanced production of organic matter in the upper water column and not enhanced preservation

planktonic foraminifera of the northern indian ocean distribution and preservation in surface sediments in the northern indian ocean planktonic foraminiferal tests accumulate in a wide variety of surface water environments and depositional settings this variability enables us to isolate the effects that surface water ecology and differential dissolution have on the distribution of planktonic foraminifera from 251 geographically widespread surface sediment samples foraminiferal abundance varies from 0 to 104 whole foraminifera in the greater than 150 m fraction per gram dry sediment values 10 characterize the three deep basins of the equatorial indian ocean and the western bay of bengal foraminiferal tests are most abundant on carbonate covered ninety east and carlsberg ridges absolute abundance patterns are mainly controlled by non ecological processes variations in dissolution resistant species rsp with water depth reveal that the foraminiferal lysocline fl varies regionally the fl is deepest 3 800 m in the equatorial region rises abruptly to 3 300 m in the arabian sea and varies from 2 600 m to near 2 000 m moving northward in the bay of bengal deep samples with anomalously low rsp 30 suggest redeposition systematic geographic and depth related variation is observed for the 17 most abundant foraminiferal species dissolution resistant species g menardii g tumida g dutertrei p obliquiloculata generally exhibit a rapid and continuous increase in relative abundance at and below the fl susceptible species g ruber g bulloides g glutinata for example exhibit a rapid and continuous decrease in relative abundance at and below the fl moderately susceptible species g conglobatus g aequilateralis g conglomerata for example rapidly increase in abundance at the fl and systematically decrease with depth below the fl principal components analysis pca of faunal data from minimally dissolved 30 rsp samples reveals important ecologically related species intercorrelations the major biogeographic gradient is the negative covarying relationship between ag bulloides g glutinata species pair and a grouping ofg sacculifer g conglobatus g aequilateralis andg ruber pca of all samples demonstrates how differential dissolution alters this and other species relationships species groupings that incorporateg ruber g menardii andg dutertrei are particularly affected by dissolution comparison of average faunal data from minimally dissolved samples in the northern indian ocean with similar samples from other tropical regions suggests varying environmental factors produce distinct faunas within the tropical ocean for example g bulloides g falconensis andg hexagona are significantly more abundant in northern indian ocean surface sediments while such species asg ruber g sacculifer g dutertrei andp obliquiloculata dominate in other tropical regions

tropically driven climate shifts in southwestern europe during mis 19 a low eccentricity interglacial the relative roles of high versus low latitude forcing of millennial scale climate variability are still not well understood here we present terrestrial marine climate profiles from the southwestern iberian margin a region particularly affected by precession that show millennial climate oscillations related to a nonlinear response to the earth s precession cycle during marine isotope stage mis 19 mis 19 has been considered the best analogue to our present interglacial from an astronomical point of view due to the reduced eccentricity centred at 785 ka in our records seven millennial scale forest contractions punctuated mis 19 superimposed to two orbitally driven mediterranean forest expansions in contrast to our present interglacial we evidence for the first time low latitude driven 5000 yr cycles of drying and cooling in the western mediterranean region along with warmth in the subtropical gyre related to the fourth harmonic of precession these cycles indicate repeated intensification of north atlantic meridional moisture transport that along with decrease in boreal summer insolation triggered ice growth and may have contributed to the glacial inception at 774 ka the freshwater fluxes during mis 19ab amplified the cooling events in the north atlantic promoting further cooling and leading to mis 18 glaciation the discrepancy between the dominant cyclicity observed during mis 1 2500 yr and that of mis 19 5000 yr challenges the similar duration of the holocene and mis 19c interglacials under natural boundary conditions

late quaternary changes in mediterranean intermediate water density and formation rate three recently acquired eastern mediterranean cores containing late quaternary sediments display a marked faunal contrast between the holocene and older sapropels it is suggested that the absence of neogloboquadrinids in the holocene sapropel and their abundance in older sapropels reflect differences in food availability related to the extent of development of a deep chlorophyll maximum layer dcm and the intensity of new primary production associated with this layer the depth of such a layer which consists of phytoplankton with a characteristic taxonomic composition is determined by the vertical hydrodynamical structure during deposition of the older sapropels the pycnocline was apparently positioned well above the base of the euphotic layer a situation that favors a pronounced dcm and an associated relatively high rate of new production shallowing of the pycnocline implies a relatively low density of the mediterranean intermediate water miw on the other hand during deposition of the holocene sapropel the pycnocline had apparently vanished due to termination of miw formation

dinosaur biostratigraphy of the edmonton group upper cretaceous alberta canada evidence for climate influence a high resolution biostratigraphic analysis of 287 dinosaurian macrofossils and 138 bonebeds in the edmonton group upper cretaceous of southern alberta provides evidence for at least three dinosa

radiolarian assemblage distributions and paleoceanography of the eastern equatorial pacific ocean during the last 127 000 years abstract mathematical treatment q mode factor analysis of radiolarian species abundance data in equatorial pacific core tops yields four oceanographically meaningful assemblages the distribution of these assemblages in surface sediments can be related to the major surface and subsurface characteristics of the equatorial circulation system western tropical mixed layer flow coastal upwelling and the oxygen minimum layer eastern equatorial divergence upwelling and the equatorial undercurrent and the subtropical water masses of both hemispheres changes in the distribution of radiolarian assemblages during the glacial interglacial cycle spanning the last 127 000 yr are observed in two equatorial pacific piston cores these changes reflect fluctuations in the boundaries of equatorial water masses in response to variations in the position and strength of the tradewind system and tend to precede major glacial interglacial transitions by several thousand years a history of atmospheric circulation in the equatorial pacific has been developed for the last 127 000 yr fluctuations in tradewind intensity north south shifts in the latitudinal position of the tradewind maxima and perhaps a change in the zonality of the tradewinds during the last 127 000 yr have been inferred from downcore quartz abundance and radiolarian assemblage distribution patterns oxygen isotopic fluctuations during the last 127 000 yr indicate that continental ice volume was much greater during glacial stage 2 29 000 b p to 11 000 b p than during glacial stage 4 73 000 b p to 61 000 b p large changes in atmospheric and oceanic circulation patterns also are indicated by the distribution of radiolarian assemblages during the two glacial periods during stage 2 oceanic circulation was more intense the southeast tradewind maximum was closer to the equator and wind stress was more meridional than during stage 4

insolation cycles as a major control of equatorial indian ocean primary production analysis of a continuous sedimentary record taken in the maldives indicates that strong primary production fluctuations 70 to 390 grams of carbon per square meter per year have occurred in the equatorial indian ocean during the past 910 000 years the record of primary production is coherent and in phase with the february equatorial insolation whereas it shows diverse phase behavior with 18o depending on the orbital frequency eccentricity obliquity or precession examined these observations imply a direct control of productivity in the equatorial oceanic system by insolation in the equatorial indian ocean productivity is driven by the wind intensity of westerlies which is related to the southern oscillation therefore it is suggested that a precession forcing on the southern oscillation is responsible for the observed paleoproductivity dynamics

paleoproductivity changes in the upwelling system of socotra somali basin nw indian ocean during the last 72 000years evidence from biological signatures abstract high resolution analyses of foraminiferal and radiolarian assemblages were performed on core md 85682 10 53 5n 52 23 e 3092 m depth 7 23 m length located close to the socotra island beneath the 10 n gyre of the upwelling area of the somali basin nw indian ocean in order to reconstruct the paleoproductivity changes during the last 72 kyr correspondence and cluster analyses of combined planktonic foraminiferal and radiolarian quantitative data show that the distribution pattern of the microfauna is partly controlled by temperature and hydrographic structures and their interrelations on water mass fertility the continuous occurrence of high abundances of foraminiferal species well known in fertile areas such as globigerinita glutinata globigerina bulloides and globigerina falconensis as well as radiolarian species characteristic of upwelling systems testifies to a sustained activity of the upwelling during the last 72 kyr downcore evolution of these biological proxies suggests an increase in paleoproductivity during isotope stages 1 and 3 which reflects a stronger upwelling activity during these periods these observations are in agreement with the results previously obtained by geochemical markers such as biogenic barium phosphorus organic matter and also trace elements related to the organic matter and indicators of redox conditions vanadium samples from isotope stage 2 record a more complex biological and geochemical signature resulting from increased terrigenous input comparison between the biological signatures obtained both under the socotra 10 n and somali 5 n upwelling areas indicates higher productivity throughout the last 72 kyr record of the socotra upwelling system in both areas a similar evolution of biological proxies indicative of high fertility is observed during isotope stages 1 and 3 however minor differences in the biological and geochemical signatures are related to local conditions prevailing beneath the two gyres

sea surface paleotemperature errors in uk 37 estimation due to alkenone measurements near the limit of detection major errors 0 5 c are produced in paleotemperature estimation with the c37 alkenone method when the amount of the diunsaturated or triunsaturated species c37 2 and c37 3 respectively approaches the limit of detection these errors are more commonly encountered with c37 3 because of its higher adsorption to gas chromatographic gc columns they are particularly relevant at low sedimentary c37 alkenone concentrations and may easily increase to temperature differences of 2 4 c depending on the uk 37 values and the ratio between the c37 3 signal and limit of detection mathematical expressions for the description of the analytical constraints derived from this detection limit problem are given a quality assurance guideline based on sample dilution three times and calculation of the sea surface temperature error is proposed for assessment of reliable measurements reevaluation of literature data in the light of the equations reported in the present study suggest that some previously reported alkenone geochemical effects such as variation in uk 37 temperatures due to postdepositional oxidation may reflect deviations in the gc measurements due to changes in c37 alkenone concentration

origins of dinosaur bonebeds in the cretaceous of alberta canada upper cretaceous dinosaur bonebeds are common in alberta canada and have attracted continuous scientific attention since the 1960s since its inception the royal tyrrell museum of palaeontology has documented the presence of hundreds of these sites and has been involved directly in the scientific study of many tens because many of these bonebeds have been used to address questions about the paleobiology and paleoecology of dinosaurs questions have arisen about bonebed origins and preservation in the cretaceous of alberta this study of 260 bonebeds delineates broad paleoenvironmental settings and associations and taphonomic signatures of assemblages as a first step in assessing patterns of dinosaur bonebed origins in the upper cretaceous of alberta bonebeds are known predominantly from the belly river group and the horseshoe canyon lower st mary river wapiti and scollard formations in these units bonebeds are mostly associated with river channel and alluvial wetland settings that were influen

radiolarian magnetobiochronology and faunal turnover across the middle late eocene boundary at ocean drilling program site 1052 in the western north atlantic ocean quantitative radiolarian assemblage analysis has been conducted on middle and upper eocene sediments zones rp16 to rp18 from ocean drilling program site 1052 in order to establish the radiolarian magnetobiochronology and determine the nature of the faunal turnover across the middle late eocene boundary in the western north atlantic ocean we recognize and calibrate forty five radiolarian bioevents to the magneto and cyclo stratigraphy from site 1052 to enhance the biochronologic resolution for the middle and late eocene our data is compared to sites in the equatorial pacific leg 199 to access the diachrony of biostratigraphic events eleven bioevents are good biostratigraphic markers for tropical subtropical locations south of 30 n the primary markers lowest occurrences of cryptocarpium azyx and calocyclas bandyca which are tropical zonal boundary markers for zones rp17 and rp18 provide robust biohorizons for correlation and age determination from the low to middle latitudes and between the atlantic and pacific oceans some other radiolarian bioevents are highly diachronous 1 million years between oceanic basins a significant faunal turnover of radiolarians is recognized within chron c17n 3n 37 7 ma where 13 radiolarian species disappear rapidly in less than 100 kyr and 4 new species originate the radiolarian faunal turnover coincides with a major extinction in planktonic foraminifera we name the turnover phase the middle late eocene turnover mlet assemblage analysis reveals the mlet to be associated with a decrease in low mid latitude taxa and increase in cosmopolitan taxa and radiolarian accumulation rates the mlet might be related to increased biological productivity rather than to surface water cooling

paleoenvironmental and climatostratigraphic insights for marine isotope stage 19 pleistocene at the montalbano jonico succession south italy abstract quantitative analyses on pollen and ostracods were performed on the montalbano jonico succession mjs through marine isotope stages mis 18 21 in order to acquire details of paleoenvironmental changes and climate pattern during mis 19 which includes the matuyama brunhes paleomagnetic boundary mbb while the mjs does not record the mbb which is the main criterion for defining the early middle pleistocene boundary it is a candidate global boundary stratotype section and point gssp for the ionian stage and middle pleistocene subseries because of its excellent exposure continuous deposition and astronomically tuned record between mis 37 and mis 16 the new 40ar 39ar age of 773 9 1 3 ka for volcaniclastic layer v4 allows the age model for the succession to be refined ostracod assemblages show significant paleodepth fluctuations at the glacial interglacial scale in agreement with the pollen distality index pinus vs caryophyllaceae amaranthaceae and ephedra which also suggests higher values during mis 19 pollen analysis provides supplementary paleoclimate data that are valuable to reconstruct temperature variation during the identified phases a major expansion of steppic vegetation at 790 ka in the uppermost mis 20 correlates with a significant cold and arid northern hemisphere climate phase as documented by a concurrent peak both in north atlantic ice rafted debris and mediterranean dust records climate conditions recorded in mis 19 3 were similar to those of the present interglacial whereas a dry climate phase marks mis 19 2 at 771 84 ka slightly above the v4 layer millennial scale climate variability occurred during mis 19 as evidenced by two abrupt short term moderately dry pollen events at 783 5 ka and 774 8 ka that could be related to a period of reduced geomagnetic field intensity through the mbb transition additional environmental chronological events accompanied this stratigraphic interval i the volcaniclastic layers v3 and v4 radiometrically dated at 801 2 19 5 ka and 773 9 1 3 ka respectively ii the co occurrence of maximum flooding and thermal maximum in agreement with the previously recorded co occurrence of the neopycnodonte community and tropical subtropical mesopelagic teleostean bonapartia pedaliota close to the increase of quercus and iii the maximum depth md between 777 3 and 773 25 ka as recorded by outer shelf upper slope macroinvertebrate fauna close to the highest value of pollen distality index in mis 19 results enhance the understanding of orbital suborbital paleoenvironmental change during the mid pleistocene and particularly of the climate pattern during mis 19 and across the mbb

maastrichtian paleocene foreland basin stratigraphies western canada a reciprocal sequence architecture palynological and magnetostratigraphic chronostratigraphic correlations of lower maastrichtian to paleocene strata along an east west western canada basin transect allow for the recognition of a reciprocal sequence architecture in nonmarine strata reference sections include three canadian continental drilling program cretaceous tertiary boundary project core holes and outcrops in alberta southern saskatchewan and north central montana the spatial and temporal position of the third order sequences provides evidence for the correlation of proximal sector regional disconformities and sedimentary wedges with distal sector sedimentary wedges and regional disconformities respectively the boundary between the two sectors is represented by a hingeline which separates the foreland basin syncline from the peripheral bulge the stratigraphies defined by reciprocal third order sequences are complicated by fourth order boundaries developed within proximal sedimentary wedges and with no correlative distal strata these results support tectonic control on foreland basin sedimentation a model for interpreting the various types of sequences in terms of foreland basin evolution vertical tectonics and orogenic cycles is provided it is argued that nonmarine sequence boundaries times of maximum uplift in the foreland region may be expressed as disconformities incised valleys top of mature paleosol levels or base of fluvial channels whereas nonmarine equivalents of marine maximum flooding surfaces times of maximum basinal subsidence may be indicated by extensive coal seams and or lacustrine sediments resume les correlations palynologiques magnetostratigraphiques et chronostratigraphiques des strates echelonnees du maastrichtien inferieur au paleocene le long du transect est ouest du bassin de la cordillere occidentale au canada permettent la reconnaissance d une ordonnance architecturale de sequences reciproques dans les strates continentales les coupes de reference incluent trois trous de forage carottes du canadian continental drilling program cretaceous tertiary boundary project et des affleurements localises en alberta dans le sud de la saskatchewan et dans le centre nord du montana la position spatiale et temporelle des sequences de troisieme ordre plaide pour la mise en correlation des discordances regionales et des depots sedimentaires en coin dans le secteur proximal avec les depots sedimentaires en coin et les discordances regionales dans le secteur distal respectivement une ligne de jonction represente la limite entre les deux secteurs qui separe le bassin d avant pays en forme de cuvette du bombement peripherique les stratigraphies definies par les sequences de troisieme ordre reciproques sont embrouillees par les limites de quatrieme ordre developpees au sein des depots sedimentaires en coin proximaux sans la presence de strates distales correlatives ces resultats appuient la these d un controle tectonique sur le bassin sedimentaire d avant pays on presente ici un modele interpretant les divers types de sequences en termes d evolution d un bassin d avant pays de tectonique verticale et de cycles orogeniques nous tentons de demontrer que les discordances les vallees entaillees les horizons sommitaux de paleosols matures ou la base des chenaux fluviaux peuvent aider a definir les limites des sequences continentales periodes de soulevement maximum dans la region de l avant pays tandis que les couches de charbon etendues et ou les sediments lacustres representent plutot les equivalents continentaux des aires d inondation maximale periodes de subsidence maximum du bassin traduit par la redaction catuneanu and sweet 703

fluvial sequence stratigraphy the wapiti formation west central alberta canada abstract outcrop exposures and high resolution subcrop data allow the description and mapping of four stratigraphic discontinuities in the fully nonmarine strata of the campanian maastrichtian wapiti formation western interior foreland basin alberta canada this framework defines four unconformity bounded depositional sequences a d based on sequence stratigraphic methodology well log patterns and facies analysis in ascending order sequence a records the transition from the underlying marine facies of the puskwaskau formation into the wapiti fluvial facies and consists of strongly progradational and aggradational stacking patterns sequences b and c show a similar pattern of basal amalgamated channel fill deposits that grade upwards into floodplain dominated strata finally sequence d is dominated by channelized sediments and extensive overbank facies an aggradational stacking pattern suggests deposition under high accommodation conditions maximum flooding surfaces are interpreted within fine grained deposits in the upper portions of sequences c and d they are tied to regionally extensive coals that accumulated more than 250 km away from the coeval shoreline this study provides new evidence that major coal seams may represent the extension of marine maximum flooding surfaces into the downstream controlled fluvial realm furthermore the new stratigraphic framework of subaerial unconformities and maximum flooding surfaces provides the means of subdividing the previously undifferentiated fully nonmarine wapiti formation into depositional sequences and component systems tracts

insolation values for the climate of the last 10 million years new values for the astronomical parameters of the earth s orbit and rotation eccentricity obliquity and precession are proposed for paleoclimatic research related to the late miocene the pliocene and the quaternary they have been obtained from a numerical solution of the lagrangian system of the planetary point masses and from an analytical solution of the poisson equations of the earth moon system the analytical expansion allows the direct determination of the main frequencies with their phase and amplitude numerical and analytical comparisons with the former astronomical solution ber78 are performed so that the accuracy and the interval of time over which the new solution is valid can be estimated the corresponding insolation values have also been computed this analysis leads to the conclusion that the new values are expected to be reliable over the last 5 ma in the time domain and at least over the last 10 ma in the frequency domain

a vertebrate microsite from a marine terrestrial transition in the foremost formation campanian of alberta canada and the use of faunal assemblage data as a paleoenvironmental indicator abstract vertebrate microfossil assemblages contain abundant fossil material of small and large bodied animals recruited from the local paleocommunity that can provide important information for reconstructing regional paleoecology the foremost formation is the oldest unit of the belly river group and records the transition from the fully marine shales of the pakowki formation to the non marine strata of the relatively well sampled oldman and dinosaur park formations although the foremost formation has relatively limited exposure and vertebrate fossil material is not abundant it does contain some important early records of major vertebrate clades from laramidia e g ceratopsids pachycephalosaurids here we document a new microfossil locality from the upper part of the formation that shows a transitional assemblage containing an abundance of terrestrial forms such as dinosaurs and other sauropsids while still showing considerable marine influence the proportion of marine taxa at this site is reduced relative to most sites known from the foremost formation though much higher than more terrestrial sites of the overlying oldman formation in addition to filling a gap in our understanding of this paleoenvironmental transition this new site preserves two particularly significant specimens a large complete cephalic spine of the hybodont shark hybodus and jaw fragments from the ratfish elasmodus this represents the first known complete cephalic spine of a hybodont shark from the cretaceous of alberta the ratfish jaw fragments represent the first published record of this group from the foremost formation further increasing our knowledge of chondrichthyan diversity in the western interior seaway comparisons of this site to other microsites from the campanian of alberta demonstrate the utility of certain key groups such as lissamphibians and chondrichthyans in determining paleoenvironments from mesozoic and cenozoic vertebrate microsite assemblage data

identification of density stratified waters in the late pleistocene north atlantic a faunal derivation abstract an expanded study of the radiolarian cycladophora davisiana in late pleistocene north atlantic marine sediments shows that over the last several hundred thousand years this species exhibits large variations in relative abundance the c davisiana curves in the north atlantic cores are quite similar with easily recognizable features common to all records minor deviations from the general pattern of this species abundance apparently reflect the response of c davisiana to specific oceanographic conditions characteristic of a particular area within the north atlantic c davisiana occurs today in high abundance 20 only in the sea of okhotsk extensive winter and early spring sea ice cover coupled with low surface water salinities during summer and fall is responsible for maintaining near freezing subsurface temperatures in this northwest pacific marginal sea as well as relatively stable temperatures and salinities at depths below a shallow subsurface temperature minimum during periods in the late pleistocene high c davisiana abundances 20 in the north atlantic were probably associated with oceanographic properties similar to those that exist in the sea of okhotsk today because of the relationship between relatively stable subsurface temperatures and salinities and high abundance levels of c davisiana analysis of this species abundance pattern at several locations throughout the high latitude north atlantic should assist in identifying source areas of deep water formation and determining the duration of deep convective processes at these sites

radiolarian responses to paleoceanographic events of the southern south china sea during the pleistocene abstract a quantitative radiolarian study at core 17957 2 from the south china sea scs allows reconstructing two paleoceanographic events occurring during the last 1500 ka based on the abundance variations of siliceous microfossils radiolarian diatom and sponge spicule the definitions of the productivity and thermocline indexes dar diatom accumulation rate and tsr thermocline surface radiolarian indexes as indicators for productivity and thermocline changes as well as changes in the species composition two distinct changes at 900 ka and 600 ka could be detected being related to the multiple transition phenomena of the mid pleistocene revolution mpr the change in the species composition at 900 ka indicated by an increase in subtropical radiolarians and a decrease in tropical radiolarians exhibits a lowering of the sea surface temperatures in the scs that can be related to a southward shift of the north equatorial current induced by variations in the northern trade wind system increasing subsurface and intermediate species and dar and tsr indexes at 700 600 ka may reflect higher sea surface productivity and shallowing thermocline caused by stronger upwelling and nutrient supply the comparison of the radiolarian signal recovered from core 17957 2 with the magnetic susceptibility signal obtained from the chinese loess plateau reveals the close connection of the climatic transitions at 700 600 ka in the southern scs to strengthening of the east asian summer monsoon circulation the spectral analyses indicate that ice mass fluctuations oxygen isotope record have clear 100 ka eccentricity dominated and processional signals after the mpr but with a more significant obliquity related response before the mpr the surface productivity e g dar and thermocline depth e g tsr index show the 100 ka dominant cyclicity before the mpr the 32 ka significant regional cyclicity for the last 1500 ka responds to the surface productivity e g dar and thermocline depth e g tsr index signals

land sea climatic variability in the eastern north atlantic subtropical region over the last 14 200 years atmospheric and oceanic processes at different timescales high temporal resolution analysis of different climatic tracers pollen foraminiferal based winter sea surface temperature sst benthic foraminiferal 18o from marine core md95 2042 retrieved off sw iberia allows us to directly compare without any chronological ambiguity mediterranean vegetation and eastern north atlantic winter sst changes for the last 14 2 kyr we identify on land and in the ocean several climatic phases such as the end of the warm and humid bolling allerod the cold and dry younger dryas and the warm and humid holocene with the mediterranean forest mf optimum between 9 6 and 8 1 kyr this record shows that at multi centennial timescale 800 years declines in forest cover generally related to dry and cool periods in southern iberia are synchronous with cold sst in the eastern part of the north atlantic subtropical gyre at multi centennial timescale changes in thermohaline circulation via freshwater content fluctuations appear to be responsible for the coupling between dryness in iberia and sst cooling in eastern north atlantic subtropical gyre in contrast some holocene events include centennial scale oscillations 100 years marked by mf declines in southern iberia concomitant with sst warming in the eastern north atlantic subtropical gyre this climatic pattern is similar to that observed at decadal timescale under the influence of the positive mode of the north atlantic oscillation nao we suggest therefore that synchronous sw iberian dryness and sst warming at centennial timescale could be explained by atmospheric fluctuations related to nao changes

radiolaria as a reflection of environmental conditions in the eastern and southern sectors of the indian ocean a new statistical approach cluster analysis and species abundance plots of radiolarian abundance counts from core tops from the eastern indian ocean between 12 s and 31 s and the southern indian ocean between 31 s and 62 5 s demonstrate the existence of environmentallyrelated provinces supporting distinct taxa assemblages these provinces are closely associated with currents in the eastern sector of the indian ocean and with fronts in the southern sector the radiolarian assemblages correlate strongly with salinity normalised total alkalinity nta at the sea surface with temperature salinity and density from the sea surface to 300 m and with dissolved oxygen and nitrate and phosphate concentrations from the sea surface to 100 m palaeo reconstructions of these parameters at the sea surface have been made for six last glacial maximum lgm samples from five eastern indian ocean cores the lgm sea surface temperature estimates are comparable with those based on planktonic foraminiferal counts of the same samples obtained by other researchers the reconstructions show that since the lgm density increased markedly along the western australian coast south of 20 s but changed little further from the western australian coast by contrast phosphate concentrations were marginally lower than modern values along the western australian coast south of 20 s but more than twice modern values in the other lgm samples the utility of various regression and calibration techniques is discussed it is concluded that probably due to the effects of differences in radiolarian habitat ocean currents and or environmental gradients only one method weighted averaging partial least squares is reliable in a study area of this size and complexity if other methods are to be used the study area must be partitioned into at least two separate regions with the major split between the eastern and southern sectors of the indian ocean 2007 elsevier b v all rights reserved

phase relationships between millennial scale events 64 000 24 000 years ago a core recovered on the iberian margin off southern portugal can be correlated with greenland ice cores using oxygen isotope variability in planktonic foraminifera which closely matches the ice core records of temperature over greenland our age model identifies the base of every interstadial between 64 000 and 24 000 years ago and uses the greenland ice core project grip timescale the oxygen isotope signal in benthic foraminifera on this grip based timescale is quite different from the planktonic record and resembles the temperature record over antarctica when this is synchronized with greenland using the record of methane in the atmospheric air in the polar ice cores we interpret the benthic record as indicating significant fluctuations in ice volume during millennial events and we suggest that antarctic temperature changed as a function of ice volume

palaeoenvironmental and palaeoclimatic reconstruction of the upper cretaceous late campanian early maastrichtian horseshoe canyon formation alberta canada abstract pedogenic features and geochemical signatures of paleosol profiles exposed in the horseshoe canyon formation hcfm were studied to reconstruct the ancient environments and climates that prevailed at high latitude 60 n in the north american western interior during the late campanian to early maastrichtian eight pedotypes representing hydromorphic moderately drained and well drained paleosols were recognized when considered within their stratigraphic context these paleosols show that palaeoenvironmental and palaeoclimatic changes occurred either gradually between major lithological subdivisions of the hcfm or relatively rapidly within subdivisions hydromorphic paleosols predominant in the coal bearing stratigraphic interval at the base of the hcfm were gradually replaced by well drained paleosols in the overlying coal poor interval while climate remained warm and humid during this change in soil drainage conditions mean annual temperature and precipitation dropped rapidly higher in section shortly prior to the campanian maastrichtian boundary without concomitant lithological or pedological changes a brief return of poorly drained paleosols in the middle of the hcfm coincides with a regional marine transgression drumheller marine tongue well drained palaeoenvironments associated with a warm and dry climate persisted through the upper part of the hcfm until a gradual return to poorly drained conditions and to a warm humid climate occurred at the top of the formation an important decline in turtle diversity through the hcfm previously attributed to climate is shown to coincide instead with changes in soil drainage conditions where aridity landscape instability and migratory barriers possibly acted as secondary limiting factors to faunal recovery

radiolarian and sedimentologic paleoproductivity proxies in late pleistocene sediments of the benguela upwelling system odp site 1084 the changing composition of radiolarian faunas from late neogene deep sea sediments has been used in recent years as a proxy for changes in marine paleoproductivity we examine radiolarian faunas organic carbon content toc opal and coarse fraction components over the last 270 000 years in sediments from odp hole 1084a drilled in a high productivity upwelling region within the benguela upwelling system off the west coast of africa age control is provided by stable oxygen isotope measurements of benthic foraminifera prior research has established that late pleistocene glacial intervals in this upwelling system generally had higher productivity than interglacials the radiolarian wade water depth ecology paleoproductivity index correlates well with toc and opal in these samples and all three parameters change in synchrony with the benthic isotope curve over all but the mis 5e 6 time interval wade inferred productivity is significantly higher in glacials than interglacials we conclude that the wade index is a useful proxy for paleoproductivity at this location as are also opal and organic carbon accumulation rates carbonate and carbonate based indices such as the accumulation rate of benthic foraminifera bfar by contrast do not correlate well either to productivity indices or to the glacial interglacial cycle and are interpreted to primarily reflect carbonate dissolution

high resolution palynological record off the iberian margin direct land sea correlation for the last interglacial complex abstract we present high resolution pollen dinocyst and isotopic data for the last interglacial complex from marine core md952042 southwestern margin of the iberian peninsula 37 48 n 10 10 w 3148 m direct land sea correlation from this core indicates that during this period north atlantic sea surface temperatures were in phase with iberian climate our palynological analysis suggests a younger dryas like event at the marine isotope stage mis 6 5 transition the analysis also indicates that the eemian spans from the lightest isotopic values of mis 5e ca 126 ky bp to the heavier isotopic values towards the mis 5e 5d transition therefore the eemian is not entirely equivalent to mis 5e pollen analysis identifies four climatic phases of low amplitude during the eemian a mediterranean climate in southwestern europe is gradually replaced by oceanic conditions the middle of the eemian is characterized by an increase in precipitation on the land and ocean associated with a slight cooling this seems to be the result of a displacement of the polar front as far south as southern europe during this period after the eemian three relatively short climatic phases on land melisey i st germain ia and montaigu cold event occurred contemporaneously with three shifts of sea surface temperatures the montaigu event first identified in terrestrial pollen sequences is therefore also recorded in core md952042 on the basis of pollen dinocyst and planktonic isotopic data our results also show that the warm periods of mis 5 are not characterized by similar climatic conditions on land

deconstructing terminations i and ii revisiting the glacioeustatic paradigm based on deep water temperature estimates benthic and planktonic oxygen isotope 18occ and mg ca analyses in two cores from the northeast atlantic have permitted the reconstruction of surface and deep water temperature tdw and 18o 18ow variations across the last two deglaciations these records allow the timing of de glacial melt water pulses reaching the northeast atlantic to be compared with the evolution of local deep water tdw 18ow conditions although each glacial termination is unique in detail a similar pattern of hydrographic change is reconstructed for both deglaciations with the first major decrease in deep water 18ow due to sea level and or purely local deep water change occurring in parallel with the onset of intensely cold glacial surface water temperatures and prior to a terminal ice rafting and melt water event the evolution of deep water across both de glaciations involved two transient incursions of cold low 18o water into the deep northeast atlantic the second of which was particularly pronounced each time these pulses of cold deep water are interpreted to reflect the incursion of water directly analogous to modern antarctic bottom water aabw and containing a significant component of brine rejected during sea ice formation the results presented here show that the same type of transient changes in deep water circulation that occurred across termination i also occurred across termination ii and that as a result of these deep ocean changes the timing of each benthic 18o termination cannot precisely reflect the timing of de glacial sea level change as many palaeoceanographic interpretations and some controversies are prone to assume such imprecision in timing especially may well extend to marine isotope stage mis boundaries in general as a principle of hydrographic variability and its expression in the geological record

sedimentological and palynological evidence of regional climatic changes in the campanian to paleocene sediments of the rocky mountain foothills canada abstract evidence of paleoclimatic variations in the upper campanian to lower paleocene post wapiabi sequence of strata is visible both laterally between the central and southern foothills and vertically in the stratigraphic record these differences are expressed by the distribution of climatically sensitive sediments i e coal and caliche and associated palynological assemblages within floodplain facies as well as by changes in the style of fluvial channels the interpretation of a semi arid environment for mature caliche paleosols is supported by the impoverished character of the associated palynological assemblages both in terms of diversity and the number of specimens recovered and by the conspicuous presence of classopollis the lateral extent of the semiarid floodplain facies and associated broad and mobile channel deposits is limited to the southern part of the basin no signs of a caliche facies have been found in the post wapiabi strata of the central foothills instead some of the floodplain deposits associated with meandering streams in this part of the basin contain numerous thick coal bearing intervals the relative climatic differences between the more humid central part and the drier southern part of the basin prevailed throughout the entire post wapiabi interval as this cannot be satisfactorily explained by the position of the sea shore or by orographic influences alone there was probably another external factor this could have been the pattern of atmospheric circulation such as that responsible for the present day climatic differences existing between the southern and central foothills semiarid floodplain facies occur at two levels in the stratigraphic column of the southern foothills in the late campanian belly river formation and in the upper maastrichtian to lower paleocene willow creek formation they correspond to regressive episodes of the epicontinental seaway intervening between these semiarid floodplain facies are the marine shales of the bearpaw formation and both overlying and underlying them thin coal beds these represent recurrent periods of swamp growth and peat accumulation in back barrier environments lagoon fill and supratidal marsh respectively because of the proximity of these swamps to the sea shore it is difficult to assess the influence of climate on the relative humidity of these settings on strictly sedimentological grounds however the terrestrial components of the palynological assemblages recovered from these marginal marine settings and correlative lacustrine sediments containing fresh water stromatolites but no coal in the central foothills are in sharp contrast with the impoverished assemblages known from the caliche facies the former are prolific diverse and contain a number of triprojectate pollen species which indicate a relatively humid climate during the latest campanian time

pollen record from colle curti and cesi early and middle pleistocene mammal sites in the umbro marchean apennine mountains central italy the palynological record from the colle curti and cesi continental deposits has been examined in order to identify the main palaeofloristic and vegetational changes between 0 99 and 0 6 0 7 ma these data show a progressive increase in aridity as well as a progressive decrease in temperature which are associated with the transition in dominance from the 41 to 100 ka cyclicity in the milankovitch orbital record during the middle pleistocene the disappearance of tsuga recorded during the lower part of the brunhes chron also has been related to a shift in global aridity during the successive open vegetational phases glacials chenopodiaceae and artemisia progressively increase whereas cyperaceae decrease forest phases interglacials are successively dominated by tsuga abies with picea and finally pinus but all lack significant expansion of broad leaved deciduous taxa palynological and sedimentological data in addition to taphonomic interpretations demonstrate the occurrence of several hiatuses in the lower parts of the interglacials these hiatuses are considered to represent the palaeoenvironmental response to climatic changes affecting local sedimentological and geomorphological conditions copyright 2000 john wiley sons ltd

evolution of millennial scale climate variability during the mid pleistocene 1 we use the oxygen isotopic composition of planktonic foraminifera globigerinoides ruber white from ocean drilling program site 1058 in the subtropical northwestern atlantic to construct a high resolution 800 year climate record spanning the mid pleistocene climate transition 410 ka to 1350 ka we investigate whether or not millennial scale instabilities in the proxy record are associated with the extent of continental glaciation g ruber 18o values display high frequency fluctuations throughout the record but the amplitude about mean glacial and interglacial 18o values increases at marine isotope stage mis 22 880 ka and is highest during mis 12 these observations support that millennial scale climate instabilities are associated with ice sheet size time series analysis illustrates that these variations have significant concentration of spectral power centered on periods of 10 12 ka and 5 ka the timing of these fluctuations agrees well or coincides with the periodicities of the second and fourth harmonics respectively of precessional forcing at the equator an insolation based origin of the millennial scale instabilities would be independent of ice volume and explains the presence of these fluctuations before the mid pleistocene climate transition as well as during interglacial intervals e g mis 37 and 17 because the amplitude of the millennial scale variations increases during the mid pleistocene transition feedback mechanisms associated with the growth of large 100 ka paced polar ice sheets may be important amplifiers of regional surface water hydrographic changes

integrated climate model oxygen isotope evidence for a north american monsoon during the late cretaceous abstract during the late cretaceous western north america was characterized by a close geographic association between the sevier highlands and the western interior seaway in this paper an atmospheric general circulation model agcm is used to simulate the impact of this geographic association on surface pressure wind direction and precipitation and it is predicted that seasonal changes in these variables resulted in a strong monsoon along the eastern flank of the sevier highlands confirmation that these model simulations are accurate is provided by isotopic data from foreland basin sediments in particular oxygen isotope records from different environments large rivers small streams and ponds and proxies unionid bivalve shells and paleosol carbonates indicate that foreland basin streams were recharged by local precipitation with high oxygen isotope ratios while large trunk rivers were recharged by high elevation precipitation this hydrologic pattern is observed from alberta to utah and is consistent with east to west monsoonal air mass movements and associated seasonal rainfall recognition of a highland driven monsoon has implication in regard to studies of fossil taphonomy of water vapor transport and of links between climate and mountain uplift and exhumation in this region

hadrosaurid edmontosaurus bonebeds from the horseshoe canyon formation horsethief member at drumheller alberta canada geology preliminary taphonomy and significance three monodominant hadrosaurid bonebeds in the horsethief member of the horseshoe canyon formation uppermost campanian in southern alberta canada are documented each bonebed is hosted by a dec

faunal assemblages from the upper horseshoe canyon formation an early maastrichtian cool climate assemblage from alberta with special reference to the albertosaurus sarcophagus bonebed the faunal assemblage from the early maastrichtian portion of the horseshoe canyon formation is described on the basis of four new vertebrate microfossil localities and remains from the albertosaurus bonebed all of the localities sampled were deposited during a cool dry climate at a palaeolatitude of 58 n thus these assemblages provide insight into a northern cool climate assemblage in the early maastrichtian of western north america this fauna is characterized by the presence of taxa with more northern affinities such as holostean a champsosaurs troodon and toothed birds warm climate taxa such as crocodylians large and diverse turtles and albanerpetontids are notable in their absence the albertosaurus bonebed locality at the top of unit 4 of the horseshoe canyon formation was deposited during the initial stages of a trend to a warmer and wetter climate that is represented in unit 5 the bonebed shares many taxa with the underlying vertebrate microfossil localities however a notable diffe

polycystine radiolarians in surface sediments from the bering sea green belt area and their ecological implication for paleoenvironmental reconstructions radiolarians in surface sediments along transects from the shelf edge along the slope into the deep basin of the northern bering sea are dominated by stylochlamydium venustum antarctissa sp 1 the spongodiscidae juvenile pseudodictyophimus gracilipes ceratospyris borealis the plagoniidae phormacantha group and plectacantha group siphocampe arachnea cycladophora davisiana and spongotrochus glacialis this dominance is most extreme on the shelf edge and slope where s venustum antarctissa sp 1 the spongodiscidae juvenile the plagoniidae and s glacialis have their highest relative abundance there is thus a close relation between radiolarian distribution and the high productivity of the bering sea green belt bsgb due to periodic sea ice melt the radiolarian depth distribution patterns indicate that some radiolarian species have specific ecological preferences s venustum the spongodiscidae juvenile and s glacialis live close to the surface water under relatively low temperature and low salinity conditions due to sea ice melting or melt water influx antarctissa sp 1 appears to dwell mainly in surface to subsurface waters but has not been recorded in trap samples of the bering sea the plagoniidae probably live in subsurface and intermediate waters s arachnea and c davisiana are intermediate to deep dwellers the close association of these radiolarians with the bsgb and specific water depths provides a valuable reference for paleoenvironmental reconstruction in the region

rapid changes of glacial climate simulated in a coupled climate model abrupt changes in climate termed dansgaard oeschger and heinrich events have punctuated the last glacial period approximately 100 10 kyr ago but not the holocene the past 10 kyr here we use an intermediate complexity climate model to investigate the stability of glacial climate and we find that only one mode of atlantic ocean circulation is stable a cold mode with deep water formation in the atlantic ocean south of iceland however a warm circulation mode similar to the present day atlantic ocean is only marginally unstable and temporary transitions to this warm mode can easily be triggered this leads to abrupt warm events in the model which share many characteristics of the observed dansgaard oeschger events for a large freshwater input such as a large release of icebergs the model s deep water formation is temporarily switched off causing no strong cooling in greenland but warming in antarctica as is observed for heinrich events our stability analysis provides an explanation why glacial climate is much more variable than holocene climate

binge purge oscillations of the laurentide ice sheet as a cause of the north atlantic s heinrich events ice rafted debris in sediment cores from the north atlantic suggests that the laurentide ice sheet lis periodically disgorged icebergs in brief but violent episodes which occurred approximately every 7 000 years here i propose that heinrich events i e what these episodes are called were caused by free oscillations in the flow of the laurentide ice sheet which arose because the floor of hudson bay and hudson strait is covered with soft unconsolidated sediment that forms a slippery lubricant when thawed the proposed heinrich event cycle has two phases the growth phase occurs when the sediment is frozen and the lis is stranded immobile on a rigid bed the volume of the lis slowly grows during this phase at a rate dictated by snow accumulation the purge phase occurs when the basal sediment thaws and a basally lubricated discharge pathway i e an ice stream such as those which occur in west antarctica today developes through hudson strait the volume of the lis rapidly equilibrates to the reduced basal friction during this phase by dumping icebergs into the labrador sea the periodicity t k sl2g 2 7000 years of the proposed heinrich event cycle is a function of the thermal conductivity and diffusivity of ice k and respectively the atmospheric sea level temperature sl in degrees celsius and the excess geothermal heat flux defined by g g k where is the atmospheric lapse rate and g is the geothermal heat flux agreement between the predicted t and the apparent periodicity implied by the marine record is the main virtue of the free oscillation mechanism i propose an alternative mechanism in which heinrich events are forced by periodic variations in external climate is implausible because periodic atmospheric temperature perturbations are strongly attenuated with depth in an ice sheet

comparison of radiolarian and sedimentologic paleoproductivity proxies in the latest miocene recent benguela upwelling system abstract estimating past ocean productivity from ocean sediments often gives different results depending on the measurement used we have examined a suite of paleoproductivity proxies in latest miocene recent sediments from dsdp site 532 and odp site 1084 two deep sea sections underlying the benguela upwelling system off the atlantic coast of southern africa the productivity history of this system has been previously established via organic carbon concentration diatom floras and alkenone based estimates of surface water temperature and shows a change from low productivity in the early pliocene to sustain high productivity in the late pliocene recent each of our samples was split and simultaneously analysed for several proxies of ocean productivity including organic carbon toc carbonate abundance of opaline radiolarians accumulation rate of benthic foraminifera bfar the radiolarian faunal composition indices upwelling radiolarian index uri and the water depth ecology index wade other proxies for opal and carbonate dissolution plus stable isotopes of benthic foraminifera comparisons between proxies in the same measured samples between sites in downcore plots and to the published productivity record for this region suggest that toc and radiolarian faunal composition particularly the wade index are good indicators of past productivity albeit with different sensitivities log linear correlation wade toc r 0 78 n 65 p

fertility tracers and monsoon forcing at an equatorial site of the somali basin northwest indian ocean abstract temporal changes in biological and isotopic tracers have successfully been used to monitor monsoon variability in the arabian sea convincing evidence that fertility indicators such as the relative abundance of the planktic foraminifer globigerina bulloides and sio 2 and ba fluxes can monitor monsoon changes has also been published time series of the 13 c content of the thermocline foraminifer neogloboquadrina dutertrei and of an upwelling radiolarian index uri have been used to reconstruct upwelling changes in the somali basin at 5 n for the last 160 kyr in order to establish a reference site for comparison with other upwelling and or fertility records from the same area a time series of 8 climatic and fertility proxies 13 c content of n dutertrei and globorotalia menardii percentages of g bulloides and of a thermocline foraminiferal group minimal 18 values of globigerinoides sacculifer n dutertrei and g menardii are investigated in the spectral domain for the last 360 kyr at a site located at the equator and outside the somali upwelling centers core md 85668 chronostratigraphies for these records are developed by correlation of oxygen isotope record of g sacculifer to the martinson standard stacked benthic oxygen isotope record the temporal resolution of the data is between 2 and 5 kyr cross spectral comparisons with etp eccentricity tilt precession composite signal were used to estimate coherences in conjunction with phase relationships and to quantify relationships between fertility and climatic indicators the timing of fertility indicator cycles at the equator shows little obliquity band or no other orbital bands coincidence with monsoon proxies of the arabian sea at the equator fertility responses are dissociated and present important leads or lags with etp signal at the three orbital bands with the exception of the thermocline foraminifera in phase with maximum eccentricity due to significant leads with etp in the timing of 13 c minima and uri cycles no relationships with the northern hemisphere radiation can be deduced at the obliquity and precessional frequency bands thermocline foraminifera cycles display significant lag with etp and ice volume minima which suggests that radiation is not the sole forcing mechanism global climatic and ice volume changes may be an important forcing mechanism for these fertility proxies the g bulloides record is more complicated with cycles in phase with arabian sea monsoon proxies at the obliquity band and 18 o minima at the precession frequency it appears that at the equator the southwest monsoon winds are not the main force driving radiolarian and foraminiferal productivity

inception of the northern european ice sheet due to contrasting ocean and insolation forcing about 115 000 yr ago the last interglacial reached its terminus and nucleation of new ice sheet growth was initiated evidence from the northernmost nordic seas indicate that the inception of the last glacial was related to an intensification of the atlantic meridional overturning circulation amoc in its northern limb the enhanced amoc combined with minimum northern hemisphere insolation introduced a strong sea land thermal gradient that together with a strong wintertime latitudinal insolation gradient increased the storminess and moisture transport to the high northern european latitudes at a time when the northern hemisphere summer insolation approached its minimum

dynamics of the monsoon in the equatorial indian ocean over the last 260 000 years abstract the coccolithophorids are excellent indicators of the variations in ocean productivity as an example the relative abundance of florisphaera profunda a species which lives exclusively in the deepest part of the photic zone constitutes a reliable monitor of the depth of the nutricline as a function of climatic variability productivity in the indian ocean is closely linked with the monsoon its intensity affects the depth of the mixing zone which deepens as the wind stress increases during the monsoon season the nutricline is shallow resulting in a higher productivity the variations in composition of coccolith assemblages in well dated oceanic sediments allows to describe the dynamics of productivity and therefore the fluctuation of the monsoon intensity core md900963 was retrieved in the equatorial indian ocean east of the maldives at a water depth of 2400 m a precise chronology was established by fine tuning the high resolution 18o record with the specmap stack coccoliths were counted from samples taken at 10 cm intervals in the core providing a resolution of 2000 years for the last 260 000 years the productivity estimates made from coccolith counts show that productivity varied greatly in the maldives area during this time the variations of the coccolith productivity index match the variations of the organic carbon content in the sediment spectral analysis reveals strong precessional cycles and weak obliquity and eccentricity cycles this implies that the solar radiation has a dominant effect on the monsoon variability south of india the productivity maxima occur during even numbered 18o stages this may indicate that the productivity events are related to increase of the winter monsoon however the analysis of the phase between the palaeoproductivity and seasonal solar radiation curves calculated for the past 260 000 years suggest an alternative hypothesis the westerlies which blow in april in the maldives area there the onset of the monsoon is in advance on the arabian sea would have a major effect on productivity since the insolation curve of the end of march at 5 n is in perfect phase with the paleoproductivity record for the last 260 000 years

origin of millennial scale climate signals in the subtropical north atlantic we present a high resolution planktonic foraminiferal stable isotope record globigerinoides ruber spanning marine oxygen isotope stages miss 6 through 8 in the northwestern subtropical atlantic ocean ocean drilling program leg 172 site 1059 the record fills a gap to produce an about 1 3 myr long continuous time series of high frequency 1 12 kyr surface ocean hydrography the first of this kind we test the hypothesis that the suborbital climate signals i e half and quarter precession cycles are linked to precession forcing in tropical latitudes semiprecession cycles present between 0 and 320 ka are of the right periodicity to relate to the dominant precession forcing 23 kyr these cycles are evident as double peaks within the given precession framework and there is good match in the amplitude modulation of the filter output and the 18o time series quarter precession cycles dominate the suborbital spectra between 320 ka and 1 3 ma periodicities are close to those expected from the harmonics of the dominant precession peaks in the 18o record but present in the time series only intermittently and their amplitude modulation does not match that of the primary precession period thus only the half precession cycles evidence a response to low latitude insolation such as that introduced by insolation maxima at the equinoxes or solstices during the course of a precession cycle additionally we find well defined rapid 1 5 2 kyr variations across the first of the interglacial maxima of mis 7 adding to evidence of non ice sheet related forcing factors in driving climate instabilities

orbital and sub orbital scale climate impacts on vegetation of the western mediterranean basin over the last 48 000 yr article i nfo high resolution pollen analysis of alboran sea core md95 2043 provides a 48 ka continuous vegetation record that can be directly correlated with sea surface and deep water changes the reliability of this record is supported by comparison with that of padul sierra nevada spain marine isotope stage mis 3 was characterised by fluctuations in quercus forest cover in response to dansgaard oeschger climate variability mis 2 was characterised by the dominance of semi desert vegetation despite overall dry and cold conditions during mis 2 heinrich events hes 2 and 1 were distinguished from the last glacial maximum by more intensely arid conditions taxon specific vegetation responses to a tripartite climatic structure within the hes are observed in mis 1 the bolling allerod was marked by rapid afforestation while a re expansion of semi desert environments occurred during the younger dryas the maximum development of mixed quercus forest occurred between 11 7 and 5 4 cal ka bp with forest decline since 5 4 cal ka bp on orbital timescales a long term expansion of semi desert vegetation from mis 3 into mis 2 reflects global ice volume trends while holocene arboreal decline reflects summer insolation decrease the influence of precession on the amplitude of forest development and vegetation composition is also detected

oxygen and carbon isotopic composition and biogeographic distribution of planktonic foraminifera in the indian ocean five planktonic foraminiferal assemblages were encountered along a north south transect in the indian ocean with the following dominant species globorotalia truncatulinoides in the southern subtropical assemblage globigerinoides ruber globigerinella aequilateralis and globorotalia menardii in the northern subtropical assemblage globigerinoides sacculifer and pulleniatina obliquiloculata in the tropical assemblage neogloboquadrina dutertrei and globigerina bulloides in the tropical upwelling assemblage and globigernoides conglobatus in the tropical arabian sea assemblage oxygen and carbon isotopic analyses were performed on three surface dwelling species of planktonic foraminifera in tropical and subtropical waters 22 30 c the 18o of globigerinoides ruber and g sacculifer varies with surface water temperature and the slope of the isotope temperature regression line is similar to that of epstein et al 1953 for marine molluscs however foraminiferal 18o values are significantly lighter than those of molluscs indicating isotopic disequilibrium comparison between plankton tows taken within and below the mixed layer at the same stations shows that g ruber has similar low 18o values in both sets suggesting that it secretes its shell within the mixed layer by contrast g sacculifer has slightly higher 18o values below than within the mixed layer because it continues to secrete calcite below the thermocline no significant 18o variations with shell size were found on the other hand 13c values were strongly size dependent i e the smaller the size the lighter the 13c comparison of living g ruber and g sacculifer with recent specimens from the surface sediment shows that the living foraminifera are generally lighter in 18o than the fossils supporting independent observations that the latter have secreted additional calcite during gametogenesis when the organisms settle freely from the euphotic zone for about 12 h and pass through waters lower in temperature than the epipelagic waters where the foraminifera form the bulk of their shells

evolution and demise of the last interglacial warmth in the subpolar north atlantic detailed faunal isotopic and lithic marine records provide new insight into the stability and climate progression of the last interglacial period marine isotope stage mis 5 which peaked approximately 125 000 years ago in the eastern subpolar north atlantic at the latitude of ireland interglacial warmth of the ice volume minimum of substage 5e mis 5e lasted 10 000 years 10 ka and its demise occurred in two cooling steps the first cooling step marked the end of the climatic optimum which was 2 3 ka long minor ice rafting accompanied each cooling step the second larger step encompassing cold events c26 and c25 was previously identified in the northwestern atlantic approximately 41c of cooling occurred between peak interglacial warmth and c25 and the region experienced an additional temporary cooling of at least 1 21c during c24 a cooling event associated with widespread ice rafting in the north atlantic beginning with c24 mis 5 was characterized by oscillations of at least 1 21c superimposed on a generally cool baseline the results of this study imply that the marine climatic optimum of the last interglacial was shorter than previously thought the finding that the eastern subpolar north atlantic cooled significantly before c24 reconciles terrestrial evidence for progressive climate deterioration at similar and lower latitudes with marine conditions our results also demonstrate a close association between modest ice rafting cooling and deep ocean circulation even during the peak of mis 5e and in the earliest stages of ice growth

a 350 ky radiolarian record off luderitz namibia evidence for changes in the upwelling regime abstract the study of radiolarian assemblages from core md 962086 provides new information on the variability in the upwelling intensity and origin of upwelled water masses over the past 350 ky in one of the major filamentous regions of the benguela upwelling system bus located off luderitz namibia the use of key radiolarian species to trace the source of upwelled waters and the use of a radiolarian based upwelling index uri to reconstruct the upwelling intensity represent the first use of radiolarians for paleoceanographic reconstructions in the bus these radiolarian based proxies indicate strongest upwelling during marine isotope stages mis 3 5 and 8 which compares well with other studies while during mis 3 and 8 the radiolarian based proxies indicate the influx of waters of southern ocean origin they also point to the increased influence of tropical waters during the lower portion of mis 5 during mis 2 4 and 6 the radiolarian assemblages indicate generally lower upwelling intensities although this signal is complicated by the increased occurrence of organic carbon in the sediments during these intervals during mis 2 there appears to be less of an input of southern ocean waters to the bus although during the also glacial mis 4 and 6 there is evidence for an increased influence of cold antarctic waters the comparison of the results from core md 962086 with other studies in the bus area indicates a non uniform pattern of upwelling intensity and advection of cold southern waters into this system during mis 2 weaker upwelling signaled by the radiolarian based proxy in mis 4 is in contrast to other studies that indicate higher productivity during this time period in general the data show that there is a strong spatiotemporal complexity in upwelling intensity in the bus and that the advection of water into it is not strongly tied to glacial interglacial variations in climate

evolution of eastern pacific warm pool and upwelling processes since the middle miocene based on analysis of radiolarian assemblages response to indonesian and central american seaways a quantitative racholarian study at ocean drilling program site 1241 in the eastern tropical pacific enables us to reconstruct paleoceanographic changes that occurred since the latest middle miocene today this site is located just under the eastern pacific warm pool epwp based on the abundance variations of radiolarian characteristic species which are indicators of upwelling and thermocline changes it is suggested that three notable changes occurred at 10 6 9 8 and 4 2 ma in the region four distinct periods of oceanographic conditions bounded by these notable changes were characterized on the basis of the following 1 stratified seawater 12 0 to 10 6 ma 2 a shallowing of the thermocline and an increasing of upwelling 10 6 to 9 8 ma 3 significant inflow of warm water to the eastern tropical pacific caused by an intensified northern equatorial countercurrent necc resulting in the formation of epwp 9 8 to 4 2 ma and 4 the reduction of the epwp and the necc and an increase in upwelling 4 2 to 0 ma the timing of these paleoceanographic events indicated the strong relations with the opening and closing of the indonesian and central american panama seaways the reduction of the epwp this study and the deepening of the thermocline in western pacific at about 4 2 ma cannariato and ravelo 1997 chaisson and ravelo 2000 indicated a change from a state resembling el nino in the late miocene and the early pliocene time to a state resembling la nina by the late pliocene c 2009 elsevier b v all rights reserved

stratigraphy of the danek bonebed upper cretaceous horseshoe canyon formation central alberta and correlations with strata in the drumheller and grande prairie regions although considerable work has been conducted on the stratigraphy and dinosaur assemblages of the horseshoe canyon formation of southern alberta equivalent strata and assemblages in central alberta remain poorly understood data from the danek bonebed edmonton alberta are beginning to fill this gap the bonebed occurs 4 m above the 9 big island coal seam this stratigraphic position lies just below the middle of the horseshoe canyon formation in the edmonton region and also lies below a thick stratigraphically significant non coaly interval that is expressed throughout central and southern alberta the stratigraphic position of the danek bonebed equates best with the uppermost horsethief member of the horseshoe canyon formation in the drumheller region and the upper part of unit 4 of the wapiti formation in the grande prairie region in both drumheller and grande prairie the correlated position of the bonebed underlies a zone of marine transgression drumheller marine tongue which in turn incl

paleohydrographic changes in the somali basin 5 n upwelling and equatorial areas during the last 160 kyr based on correspondence analysis of foraminiferal and radiolarian assemblages this study documents the biological signatures impressed upon the sedimentary record underlying both the 5 n upwelling system of the somali current and the equatorial area of the somali basin out of the upwelling influence the evolution of these two distinct hydrographic systems is compared for the last 160 kyr correspondence and cluster analyses are performed on combined radiolarian and planktonic foraminiferal quantitative data in order to study the changes of the planktonic assemblages through time and space the upwelling radiolarian index uri is used as a productivity proxy the water temperature and hydrographic structure of the upper water masses appear to be the major factors controlling the distribution patterns of the fauna the relative abundances of three groups of foraminifera cold water form dextral n pachyderma mixed layer dwellers g trilobus g ruber g sacculifer g conglobatus and g glutinata and thermocline dwellers g menardii g tumida n dutertrei g crassaformis and p obliquiloculata follow distinct evolutionary patterns at the two sites during the last 160 kyr at the equatorial site core md 85668 downcore fluctuations in the relative abundances of the three groups are closely related to the glacial interglacial cyclicity and provide some insights into the interpretation of hydrographic changes the dominance of the mixed layer foraminifera at the transition intervals between isotope stages 6 5 and 2 1 combined with weak uri values is thought to reflect the reorganization of the oceanographic circulation these short term events with a duration of 5000 year could be related to the rapid inflow of oxygen depleted water through the indonesian straits as a result of sea level rise during deglaciation underneath the 5 n gyre core md 85674 the response to global climatic changes is overprinted by the regional effect of the somalian upwelling which has been persistent over the last 160 kyr

filtering of milankovitch cycles by earth s geography abstract earth s land sea distribution modifies the temperature response to orbitally induced perturbations of the seasonal insolation we examine this modification in the frequency domain by generating 800 000 yr time series of maximum summer temperature in selected regions with a linear two dimensional seasonal energy balance climate model previous studies have demonstrated that this model has a sensitivity comparable to general circulation models for the seasonal temperature response to orbital forcing on land although the observed response in the geologic record is sometimes significantly different than modeled here differences attributable to model limitations and feedbacks involving the ocean atmosphere cryosphere system there are several results of significance 1 in mid latitude land areas the orbital signal is translated linearly into a large 10 c seasonal temperature response 2 although the modeled seasonal response to orbital forcing on antarctica is 6 c the annual mean temperature effect

taphonomy of debris flow hosted dinosaur bonebeds at dalton wells utah lower cretaceous cedar mountain formation usa abstract a taphonomic study of the lower cretaceous dalton wells dw dinosaur bonebeds near moab utah provides insight into the origins preservational biases and paleobiological significance of one of the richest and most diverse early cretaceous dinosaur sites known the bonebeds occur in a stacked succession of debris flows at the base of the yellow cat member of the cedar mountain formation which was deposited in a seasonally dry alluvial lacustrine setting although only 5 of the locality has been collected more than 4200 bones were recovered representing an assemblage overwhelmingly dominated by dinosaurs with a minimum of 67 individuals that represent at least eight genera the assemblage also includes eight elements from four non dinosaurian reptiles the dinosaur fauna is sauropod dominated mni minimum number of individuals 41 a basal macronarian mni 15 venenosaurus mni 3 a camarasaurid mni 2 and a large number mni 21 of generically unassigned sauropod elements other dinosaurs include the theropods utahraptor mni 9 nedcolbertia mni 2 a possible ornithomimid mni 2 plus a large iguanodontid mni 4 and the ankylosaurid gastonia mni 9 patterns of skeletal articulation and clustering ontogenetic representation and bone surface modification indicate that the assemblage accumulated and was exposed for more than a year as the result one or more multiple mass mortality events likely droughts that culled large numbers of subadults from the biocoenose carcasses and disarticulated elements were reworked then later transported a short distance and buried by a succession of debris flows skeletal representation data patterns of sorting breakage burrows abrasion and scratch marks provide evidence for sorting trampling and scavenging prior to debris flow reworking pre debris flow sorting is attributed to earlier hydraulic winnowing of easily transported elements the intensity and thoroughness of breakage involving 97 of the elements suggest highly focused high load impacts compatible with trampling by sauropods and iguanodontids lightly abraded and vertically displaced elements indicate episodes of trampling in soft mud trampling occurred before and after debris flow transport theropod tooth marks are uncommon but bone scavenging by osteophagous insects was common and severe resulting in substantial damage to articular surfaces comparisons of dw and other debris flow hosted bonebeds indicate that there are few consistent patterns among fossil assemblage and bone modification data however there are numerous similarities in the geological and spatial taphonomy datasets from these sites resulting from the similar physico hydraulic conditions under which elements were transported reworked and buried geologically and taphonomically dalton wells is similar to the blagoveshchensk monodominant hadrosaur bonebed in the udurchukan formation of eastern russia which also is interpreted as a debris flow hyperconcentrated flow deposit dalton wells also shares geologic and taphonomic characteristics with four bonebeds southeast of the town of green river utah and all occur at the base of the yellow cat member the uniform stratigraphic occurrences of the dalton wells blagoveshchensk and the green river sites resting on an unconformity and their shared sedimentologic and taphonomic features indicate that these sites originated in response to similar tectonic depositional and biostratinomic factors

investigating boron isotopes in a middle jurassic micritic sequence primary vs diagenetic signal boron isotope abundance in carbonates provides a powerful proxy for seawater ph reconstructions nevertheless application of this proxy on bulk rocks has never been clearly investigated herein boron isotopes were measured in early bajocian samples from the terminilletto section italy to explore the meaning of bulk rock 11b values in paleo environmental investigations in the southwestern tethys the early bajocian is marked by a change in sedimentation from calcareous to radiolaritic lithologies concomitant with a 13c positive excursion and a sedimentary hiatus in several calcareous sections the isotopic compositions of boron extracted from terminilletto samples range from 10 to 12 and boron content from 0 75 to 1 45 ppm both lower than modern ranges this implies either diagenesis or a lower boron concentration in jurassic seawater boron isotopic compositions are compared to major and trace element analyses to investigate potential alteration of the carbonate primary signal fe and al contents provide useful information on both clay contamination and sedimentation style the 11b values measured in carbonates constrain the boron isotopic composition of the precipitating fluid either seawater or derived from seawater regarding that both 11b and 18o are consistent with marine signatures jurassic seawater 11b might have been lower than the modern one the 11b variations consistent with micropaleontological observations suggest a seawater alkalinization reflecting the atmospheric co2 decrease after a probable phase of volcanism intensification prior to the aalenian bajocian boundary the carbonate crisis itself might also have promoted ph rise through progressive co32 accumulation in seawater

iberian margin sea surface temperature during mis 15 to 9 580 300 ka glacial suborbital variability versus interglacial stability 1 past sea surface water conditions of the western iberian margin were reconstructed based on biomarker analyses of a marine deep sea core md03 2699 from the estremadura spur north off lisbon providing new insights into orbital and suborbital scale climate variability between marine isotope stage mis 15 to mis 9 580 to 300 ka we use biomarker based proxy records such as the alkenone unsaturated index to estimate sea surface temperature sst the total alkenone concentration to reconstruct phytoplankton productivity and terrestrial biomarkers to evaluate the continental input the results extend the existing biomarker record namely the sst for the iberian margin back to the sixth climatic cycle 580 ka a general trend of stable interglacials contrasts with glacial periods and glacial inceptions which are marked by high frequency variability thus several short lived climatic coolings were identified by large sst decreases the occurrence of ice rafted detritus and high percentages of the tetraunsaturated alkenone c37 4 some of these events were extremely cold and similar in their general trends to the well known heinrich events of the last glaciation we identified eight heinrich type events between 580 and 300 ka the general deglaciation pattern detected between mis 15 and mis 9 is similar in their general trends to that characterizing the more recent climatic cycles i e marked by two coolings separated by a short warming episode which may reflect the southward northward and southward migration of the polar front

age dating and the orbital theory of the ice ages development of a high resolution 0 to 300 000 year chronostratigraphy using the concept of orbital tuning a continuous high resolution deep sea chronostratigraphy has been developed spanning the last 300 000 yr the chronology is developed using a stacked oxygen isotope stratigraphy and four different orbital tuning approaches each of which is based upon a different assumption concerning the response of the orbital signal recorded in the data each approach yields a separate chronology the error measured by the standard deviation about the average of these four results which represents the best chronology has an average magnitude of only 2500 yr this small value indicates that the chronology produced is insensitive to the specific orbital tuning technique used excellent convergence between chronologies developed using each of five different paleoclimatological indicators from a single core is also obtained the resultant chronology is also insensitive to the specific indicator used the error associated with each tuning approach is estimated independently and propagated through to the average result the resulting error estimate is independent of that associated with the degree of convergence and has an average magnitude of 3500 yr in excellent agreement with the 2500 yr estimate transfer of the final chronology to the stacked record leads to an estimated error of 1500 yr thus the final chronology has an average error of 5000 yr

air sea temperature decoupling in western europe during the last interglacial glacial transition between 80 000 and 70 000 years ago climate cooled and ice sheets in the high northern latitudes expanded pollen and microfossil data from marine sediments indicate that an increasing thermal gradient between cold air and warmer oceans could have supported continental ice growth

the alberta foreland basin relationship between stratigraphy and cordilleran terrane accretion events a foreland basin sequence resulting from accretion of a terrane to a continental passive margin ideally should be unconformity bounded with a shallowing upward pattern like the classic flysch to molasse sequence of alpine foreland basins the basal unconformity is cut as the peripheral bulge associated with lithospheric flexure migrates cratonward ahead of the basin and the advancing overthrusts the shallowing occurs because sediment supply at first is low early stages of accretion near the continental slope generate little or no topography above sea level later stages result in significant tectonic uplift and much sediment is shed into the foreland filling the basin the upper unconformity is cut as lithospheric bending stresses are relaxed following overthrusting and reduction of the flexural load on the lithosphere through erosion and or tectonic denudation of the overthrusts causes regional uplift or basin rebound actual sequences show differences from this idealized version in that i

four climate cycles of recurring deep and surface water destabilizations on the iberian margin centennial climate variability over the last ice age exhibits clear bipolar behavior high resolution analyses of marine sediment cores from the iberian margin trace a number of associated changes simultaneously proxies of sea surface temperature and water mass distribution as well as relative biomarker content demonstrate that this typical north south coupling was pervasive for the cold phases of climate during the past 420 000 years cold episodes after relatively warm and largely ice free periods occurred when the predominance of deep water formation changed from northern to southern sources these results reinforce the connection between rapid climate changes at mediterranean latitudes and century to millennial variability in northern and southern polar regions

forcing of atlantic equatorial and subpolar millennial cycles by precession abundance cycles of the marine alga florisphaera profunda centered on a period of 7600 carbon 14 years 8400 calendar years are present in high resolution records from the equatorial atlantic spanning 0 to 45 000 years ago these cycles correlate with heinrich events 1 through 5 which document rapid changes in continental ice melting around the subpolar north atlantic these variations in f profunda are a direct response to modulation in zonal wind driven divergence produced by a precessional component of orbital variation during a time of reduced eccentricity modulation

sea surface temperatures did not control the first occurrence of hudson strait heinrich events during mis 16 1 hudson strait hs heinrich events ice rafting events in the north atlantic originating from the laurentide ice sheet lis are among the most dramatic examples of millennial scale climate variability and have a large influence on global climate however it is debated as to whether the occurrence of hs heinrich events in the eastern north atlantic in the geological record depends on greater ice discharge or simply from the longer survival of icebergs in cold waters using sediments from integrated ocean drilling program iodp site u1313 in the north atlantic spanning the period between 960 and 320 ka we show that sea surface temperatures ssts did not control the first occurrence of hs heinrich like events in the sedimentary record using mineralogy and organic geochemistry to determine the characteristics of ice rafting debris ird we detect the first hs heinrich like event in our record around 643 ka marine isotope stage mis 16 which is similar as previously reported for site u1308 however the accompanying high resolution alkenone based sst record demonstrates that the first hs heinrich like event did not coincide with low ssts thus the hs heinrich like events do indicate enhanced ice discharge from the lis at the end of the mid pleistocene transition not simply the survivability of icebergs due to cold conditions in the north atlantic

ocean circulation ice sheet growth and interhemispheric coupling of millennial climate variability during the mid pleistocene ca 800 400ka abstract stable carbon and oxygen isotopes from benthic and planktic foraminifers planktic foraminifer assemblages and ice rafted debris from the north atlantic site u1314 integrated ocean drilling program expedition 306 were examined to investigate orbital and millennial scale climate variability in the north atlantic and its impact on global circulation focusing on the development of glacial periods during the mid pleistocene ca 800 400 ka glacial initiations were characterized by a rapid cooling 6 10 c in less than 7 kyr in the mean annual sea surface temperature sst increasing benthic 18o values and high benthic 13c values the continuous increase in benthic 18o suggests a continuous ice sheet growth whereas the positive benthic 13c values indicate that the flow of the iceland scotland overflow water isow was vigorous strong deep water formation in the norwegian greenland sea promoted a high transfer of freshwater from the ocean to the continents however low ssts at site u1314 suggest a subpolar gyre cooling and freshening that may have reduced deep water formation in the labrador sea during glacial initiations once the 3 5 threshold in the benthic 18o record was exceeded ice rafting started and ice sheet growth was punctuated by millennial scale waning events which returned to the ocean part of the freshwater accumulated on the continents ice rafting events were associated with a rapid reduction in the isow benthic 13c values dropped 0 5 1 and followed by millennial scale warmings the first two millennial scale warm intervals of each glacial period reached interglacial temperatures and were particularly abrupt 6 10 c in 3 kyr subsequent millennial scale warm events were cooler probably because the amoc was rather reduced as suggested by the low benthic 13c values these two abrupt warming events that occurred at early glacial periods were also observed in the antarctic temperature and co2 records suggesting a close correlation between both hemispheres the comparison of the sea surface proxies with the benthic 18o record as the southern sign indicates the presence of a millennial scale seesaw pattern similar to that seen during the last glacial period

palaeogeography of radiolarite and organic rich deposits in mesozoic tethys siliceous and marine organic rich deposits are sometimes associated sometimes separate in space and time however both are generally accepted to be the result of high planktonic productivity among the siliceous marine deposits the phtanite family facies is distinguished from the radiolarite family facies by several characteristics they contain organic material and as a result are blackish vs red green for radiolarite facies their time of deposition corresponds with strong faunal modifications and they are deposited generally in shallower environments a palaeogeographic analysis of locations of tethyan biosiliceous and marine organic rich rocks both resulting from a high planktonic palaeoproductivity for three mesozoic high sea level intervals toarcian kimmeridgian and cenomanian show a during jurassic times these tethyan deposits were dissociated the siliceous deposits being closer to open ocean waters than the organic rich ones this is a common disposition in modern upwelling systems and suggests a common process b during cretaceous times these tethyan deposits were often associated i e both occur at the same site and are probably the result of a different process from that in the jurassic

reconstruction of oceanic circulation patterns in the tropical pacific across the early middle miocene boundary as inferred from radiolarian assemblages abstract although there have been attempts to infer neogene oceanic circulation patterns in the tropical pacific on the basis of multiple marine proxies oceanic circulation patterns across the early middle miocene boundary are still poorly understood despite paleoclimate having significantly changed during this interval in this study we reconstruct the changes in tropical oceanic circulation patterns in the pacific across the early middle miocene boundary based on radiolarian assemblages obtained at integrated ocean drilling program site u1335 in the eastern tropical pacific the radiolarian upwelling taxa increased during four intervals 18 4 18 1 ma 16 9 15 7 ma 15 2 14 6 ma 14 2 13 4 ma radiolarian temperature index rti was calculated using the relative abundances of the warm water cluster b1 and cool water taxa cluster b2 in order to evaluate relative temperature fluctuations of the surface water the sea surface temperature index was relatively high from 16 8 to 16 0 ma and gradually decreased from 16 0 to 14 6 ma subsequently the temperature index decreased stepwise at 13 9 and 13 4 ma and became relatively low from 13 4 to 12 7 ma comparison of the rti record in the eastern tropical pacific to the climatic index based on the benthic foraminiferal 18o record shows that variability in the two records follows a roughly similar trend from the early to the middle miocene however the sea surface temperature record does not indicate a sharp increase in warmth in the eastern tropical pacific during the mid miocene climatic optimum 1 mmco 1 as suggested by the benthic isotopic record this is likely because of increased upwelling of cool nutrient rich water at this time beginning in the latest early miocene 17 ma radiolarian assemblages were dominated by different taxa in the eastern and western tropical pacific this pattern is interpreted as indicating a shallower thermocline in the east and a deeper thermocline in the west based on the relative abundance of the upwelling taxa there is an overall increasing trend in this difference since the latest early miocene we tie these events to the effective closure of the indo pacific seaway and the development of a substantial western pacific warm pool along with the development of a strong equatorial undercurrent

tectonic stratigraphic and sedimentologic significance of a regional discontinuity in the upper judith river group belly river wedge of southern alberta saskatchewan and northern montana the lithostratigraphic interval between the taber and lethbridge coal zones in the upper portion of the nonmarine judith river group of southeastern alberta is divisible into two lithostratigraphic units separated by a regionally extensive and diachronous discontinuity the lower unit referred to here as the oldman formation is characterized by very fine grained to fine grained sandstones that contain fewer than 2 volcanic rock fragments sandstone bodies with numerous sets of horizontally stratified sandstone showing little or no evidence of lateral accretion siliceous paleosols ganisters and a relatively high gamma ray signal in the upper half of the formation the oldman formation comprises deposits of a low sinuosity perhaps ephemeral fluvial system that originated in the southern cordillera of canada and northern montana and flowed northeastward perpendicular to the axis of the alberta basin the upper unit is assigned to a new formation the dinosaur park formation and is characterized by

upwelling intensity and ocean productivity changes off cape blanc northwest africa during the last 70 000 years geochemical and micropalaeontological evidence abstract the accumulation of biogeochemical organic carbon calcium carbonates molybdenum and iodine micropalaeontological benthic foraminifera and terrigenous markers grain size si al zr al k al over the last 70 000 years in one core sedorqua 11k on the northwest african margin off cap blanc has been used to reconstruct past variations of local upwelling intensity and oceanic productivity the study demonstrates that productivity in this area increased during stage 3 particularly between 40 000 and 50 000 yr b p and during the last deglaciation between 6000 and 15 000 yr b p during most of isotopic stage 2 and particularly during the last glacial maximum productivity was much lower these variations can be attributed to changes in local wind stress and seasonality that are related to variability in monsoon pressure intensity because of the establishment of upwelling cells over the shelf due to high sea level the conditions of sedimentation during the last 5 6 thousend years on the upper slope site 11k are largely dominated by advection from the shelf leading to strong sorting prior to deposition advection seems to have been minor during the other periods of enhanced productivity a conceptual model is proposed to link the productivity variations to atmospheric circulation in particular to the wind stress direction and seasonality

evolution of ocean temperature and ice volume through the mid pleistocene climate transition earth s climate underwent a fundamental change between 1250 and 700 thousand years ago the mid pleistocene transition mpt when the dominant periodicity of climate cycles changed from 41 thousand to 100 thousand years in the absence of substantial change in orbital forcing over this time an increase occurred in the amplitude of change of deep ocean foraminiferal oxygen isotopic ratios traditionally interpreted as defining the main rhythm of ice ages although containing large effects of changes in deep ocean temperature we have separated the effects of decreasing temperature and increasing global ice volume on oxygen isotope ratios our results suggest that the mpt was initiated by an abrupt increase in antarctic ice volume 900 thousand years ago we see no evidence of a pattern of gradual cooling but near freezing temperatures occur at every glacial maximum

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

rapid switch in monsoon wind induced surface hydrographic conditions of the eastern arabian sea during the last deglaciation abstract surface water hydrography in the arabian sea is primarily governed by the asian monsoon wind system changes in the composition of fossil planktic foraminiferal assemblages and sea surface temperatures sst in sediment core sk17 retrieved from offshore of central india are used to decipher past changes in sea surface hydrographic conditions linked mainly to the winter monsoon winds the planktic foraminiferal assemblage and the sst records indicate a rapid switch in sea surface hydrographic conditions around 17 5 ka bp marking the end of last glacial period the data show that intensified winter winds during 17 5 23 5 ka bp resulted in nutrient injection into surface waters and eutrophic conditions mainly through deep vertical mixing and or moderate upwelling and reduction in winter wind intensity caused stratification characterized by the high tropical sst since 17 5 ka bp the timing of the rapid switch in seawater conditions caused by a drop in strength of winter monsoon winds is coeval with the cold climate excursion in the northern hemisphere heinrich event 1 suggesting that the two areas are climatically linked

paleoenvironmental and paleoecological implications of permian guadalupian radiolarian and geochemical variations in the lamar limestone delaware basin west texas usa abstract geochemical proxies integrated with well preserved radiolarian data from the lamar limestone and lower part of the reef trail member of the bell canyon formation provide insights into paleoceanographically and climatically driven controls on radiolarian distribution in the northern part of the delaware basin of west texas during late guadalupian time data from a section of the lamar limestone 8 9 m 500 kyr interval indicate that major variations between sphaerellarian dominated and follicucullus dominated faunas appear to be controlled by fluctuations in nutrient supply and salinity geochemical parameters of bulk carbonate carbon and oxygen isotopes 13 c carb and 18 o carb organic carbon isotope 13 c org and total organic carbon toc were analyzed and show variations on two scales on a fine scale sphaerellarian dominated beds are associated with a relatively siltier lithology higher toc and higher radiolarian richness but lower diversity and are interpreted as the result of a rise in productivity stimulated from increased terrestrial input the radiolarian variations and geochemical evidence imply that the permian spongiose spumellarians are more opportunistic than follicucullus albaillellids in response to eutrophication on a broad scale 18 o carb variations in limestone samples are interpreted mainly as a proxy for paleosalinity in response to changes in basin circulation mg ca ratios from the carbonate fraction co vary with 18 o carb and are used as an additional paleosalinity proxy in this basin the limestone beds in the middle part of the section have lighter 18 o carb values compared to limestone beds above and below and likely represent the interval when the delaware basin was less restricted and had relatively normal marine salinity impacts of diagenesis are mild but are likely the cause for systematically light 18 o carb values in silty limestone beds in the middle interval the mg ca ratios and 18 o carb values in the limestone samples both increase from the middle to the top of the section implying a gradually enhanced evaporitic environment coupled with increased salinity towards the top section collectively these data paint a picture of intermittent restriction in the delaware basin prior to the change to a dominantly evaporative regime in the late permian and on a finer scale show pronounced and frequent ecological fluctuations that appear to be driven by fluxes in terrestrial input and to some extent paleoproductivity

a new ceratopsid from the foremost formation middle campanian of alberta xenoceratops foremostensis gen et sp nov a new centrosaurine ceratopsid from the foremost formation campanian of alberta is described based on frill material from at least three adult sized individuals collected from a low density bone bed the material can be assigned to centrosaurinae based on features of the preserved squamosal although the parietals are incomplete the shape of the diagnostic parietal can be inferred from several overlapping serial elements the parietal of the new taxon shares with all other centrosaurines except centrosaurus apertus spike like ornamentation at the posterolateral p3 locus under traditional coding methods at approximately 78 ma it is the oldest known canadian ceratopsid approximately 0 5 ma older than albertaceratops from the lower oldman formation of canada and approximately 1 0 ma younger than diabloceratops from the wahweap formation of utah a phylogenetic analysis resolves the new taxon as the basalmost centrosaurine and places centrosaurus brinkm

introduction to the special issue commemorating the 30th anniversary of the royal tyrrell museum of palaeontology with a summary of the museum s early history and its research contributions located just west of drumheller in southern alberta canada the royal tyrrell museum of palaeontology rtmp is nestled among outcrops of the upper cretaceous horseshoe canyon formation exposed along the red deer river valley fig 1 since it officially opened on 25 september 19851 the museum has become one of alberta s must see tourist attractions a significant contributor to the local economy and earned an international reputation for the quality of its palaeontological collections and the research conducted by its scientists the rtmp is unique within canada in being the only government supported museum dedicated to palaeontology and it is one of the few such institutions in the world fig 1 the royal tyrrell museum of palaeontology a front of museum and main entrance circa 2010 looking westwards and with horizontal beds of the upper cretaceous horseshoe canyon formation exposed in the walls of the red deer river valley in the distance b aerial photograph oblique angle and looking to the north northeast the museum sits on top of the number 7 coal seam sensu gibson 1977 and at the base of the horsethief member of the horseshoe canyon formation d a eberth pers comm 2015 that stratigraphic position correlates with an age of about 71 5 ma i e late campanian and lies within the upper part of the edmontosaurus regalis pachyrhinosaurus canadensis dinosaur assemblage zone see eberth et al 2013 fig 6 c the iconic running theropod logo that until recently graced the exterior of the museum below a life sized tyrannosaurid sculpture by brian cooley one of many such sculptures by cooley that have been featured at the museum since its opening in 1985 and with the education wing opened in 2003 as the atco tyrrell learning centre in the background d the cretaceous alberta life sized diorama opened in 2007 an example of a rtmp exhibit that relies heavily on discoveries and interpretations by museum researchers in this case work done in the albertosaurus bonebed and at other localities throughout the horseshoe canyon formation all photographs courtesy of the royal tyrrell museum of palaeontology this special issue of the canadian journal of earth sciences presents a collection of papers commemorating the rtmp s 30th or pearl anniversary our rationale for doing a 30th anniversary volume was two fold first it is an opportunity to showcase the breadth of research conducted by current and former museum scientists as well as by some colleagues having a history of collaboration with the rtmp the 13 invited papers included in this volume are a mix of review and original research papers all thematically focused on the geology and palaeontology of alberta to varying degrees each contribution is the result of work supported by the rtmp and relies on specimens housed in the museum s collections second the 30th anniversary is an opportunity to reflect on the rtmp s history and its research program as is typical for most institutions the rtmp has done little to formally document its own history this year likely will be the last major milestone for which the original generation of museum staff are still working and available to share their recollections about the museum fieldwork and research already deaths and departures have winnowed away part of the original

radiolaria as indicators of upwelling processes the peruvian connection abstract in the sediments along the coastal region of peru certain radiolarian species have preferences to waters associated with upwelling such is the case forpolysolenia murrayana in the upwelling areas fed by equatorial water and forcenosphaera sp in the upwelling areas fed by temperate subantarctic water cycladophora davisiana appears to frame the upwelling centers suggesting that it prefers regions near thermic fronts the down core records of these species as well as records of quartz and organic carbon are depicted in three14c and 18o dated cores located along the pacific coast of south america between 11 and 13 s they suggest that both the eolian and oceanic circulation were more intense during the last glacial stage approximately between 33 000 and 11 000 years ago than during the present postglacial at these latitudes the intensification in circulation was not only accompanied by an increased coastal upwelling and in turn by an increased primary productivity but also by a larger supply of temperate waters to the area

oceanographic conditions associated with high abundances of the radiolarian cycladophora davisiana abstract the cosmopolitan radiolarian cycladophora davisiana usually comprises less than 5 of the radiolarian fauna in holocene sediments in recent sediments from the sea of okhotsk however this species frequently represents more than 20 of the radiolarian assemblage at times during the late pleistocene abundances of this species in excess of 40 are recorded in marine sediments from high latitude oceans 40 of both hemispheres the sea of okhotsk apparently represents a modern analogue of climatic and oceanographic conditions that existed throughout large portions of high latitude oceans at times during the late pleistocene the near surface water structure of the sea of okhotsk is characterized by a low salinity surface layer with a strong temperature minimum near its base the low surface salinities are responsible for maintaining near freezing subsurface temperatures as well as establishing relatively stable temperatures and salinities at depths below the temperature minimum this water structure is produced at least in part by intense freezing of sea ice in winter with subsequent summer melting the physical characteristics of the upper water column affect the abundance and activity of shallow dwelling flora and fauna while providing a stable subsurface environment for deeper dwelling fauna

the marine isotope stage 19 in the mid latitude north atlantic ocean astronomical signature and intra interglacial variability abstract since the seminal work by hays et al 1976 a plethora of studies has demonstrated a correlation between orbital variations and climatic change however information on how changes in orbital boundary conditions affected the frequency and amplitude of millennial scale climate variability is still fragmentary the marine isotope stage mis 19 an interglacial centred at around 785 ka provides an opportunity to pursue this question and test the hypothesis that the long term processes set up the boundary conditions within which the short term processes operate similarly to the current interglacial mis 19 is characterised by a minimum of the 400 kyr eccentricity cycle subdued amplitude of precessional changes and small amplitude variations in insolation here we examine the record of climatic conditions during mis 19 using high resolution stable isotope records from benthic and planktonic foraminifera from a sedimentary sequence in the north atlantic integrated ocean drilling program expedition 306 site u1313 in order to assess the stability and duration of this interglacial and evaluate the climate system s response in the millennial band to known orbitally induced insolation changes benthic and planktonic foraminiferal 18o values indicate relatively stable conditions during the peak warmth of mis 19 but sea surface and deep water reconstructions start diverging during the transition towards the glacial mis 18 when large cold excursions disrupt the surface waters whereas low amplitude millennial scale fluctuations persist in the deep waters as recorded by the oxygen isotope signal the glacial inception occurred at 779 ka in agreement with an increased abundance of tetra unsaturated alkenones reflecting the influence of icebergs and associated meltwater pulses and high latitude waters at the study site after having combined the new results with previous data from the same site and using a variety of time series analysis techniques we evaluate the evolution of millennial climate variability in response to changing orbital boundary conditions during the early middle pleistocene suborbital variability in both surface and deep water records is mainly concentrated at a period of 11 kyr and additionally at 5 8 and 3 9 kyr in the deep ocean these periods are equal to harmonics of precession band oscillations the fact that the response at the 11 kyr period increased over the same interval during which the amplitude of the response to the precessional cycle increased supports the notion that most of the variance in the 11 kyr band in the sedimentary record is nonlinearly transferred from precession band oscillations considering that these periodicities are important features in the equatorial and intertropical insolation these observations are in line with the view that the low latitude regions play an important role in the response of the climate system to the astronomical forcing we conclude that the effect of the orbitally induced insolation is of fundamental importance in regulating the timing and amplitude of millennial scale climate variability

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

mapping holocene upwelling in the eastern equatorial pacific using radiolaria recently an assemblage of radiolaria characteristic of upwelling has been described from the peru current oman margin and somalian gyre regions and subsequently from the eastern tropical atlant

evidence for taphonomic size bias in the dinosaur park formation campanian alberta a model mesozoic terrestrial alluvial paralic system a study of the distribution of dinosaurian body masses in the dinosaur park formation dpf campanian southern alberta reveals a prominent negative skew a pattern distinct from those of modern terrestrial faunas we find a direct and robust correlation between taxon size estimated live body mass and known completeness there is a clear dichotomy between large and small bodied taxa at around 60 kg in which taxa less than 60 kg are significantly less complete mean completeness 7 6 than those with an estimated mass of 60 kg or greater mean 78 2 along with completeness there is also a strong association of body size and taphonomic mode with small taxa known largely from isolated and occasionally associated remains and large taxa known from articulated skeletons in addition there is a significant correlation between taxon body mass and both date of discovery and of description with taxa 60 kg the rates of both cumulative discovery and description for large taxa are best described by a logarithmic curve nearing an asymptote whereas small taxa show either a linear or power increase through time this suggests that our current knowledge of the large bodied dinosaur assemblage is reasonably representative of the true biological fauna with few discoveries likely to be made in the future however small taxa are greatly underestimated in both their diversity and abundance with many more potential discoveries to be made given that 1 the sedimentary deposits and fossil assemblages in the dpf together represent one of the best studied examples of a mesozoic alluvial paralic terrestrial palaeoecosystem and 2 similar patterns have been suggested but not documented for other mesozoic terrestrial ecosystems in the western interior of north america we suggest that this pattern of size bias may typify vertebrate fossil assemblages in terrestrial mesozoic systems if so such biases must be considered before patterns of diversity in dinosaur communities through time can be considered accurate or used to compare and interpret mesozoic palaeoecosystems

pliocene pleistocene radiolarian events and magnetostratigraphic calibrations for the tropical indian ocean johnson d a schneider d a nigrini c a canlet j p and kent d v 1989 pliocene pleistocene radiolarien events and magnetostratigraphic calibrations for the tropical indian ocean micropaleontol 14 33 64 a composite of four piston cores from the central indian basin and adjacent ninetyeast ridge has yielded a continuous magnetobiostratigraphic reference section for most of the pliocene and the pleistocene 0 0 4 5 ma we identified thirty three radiolarian events first or last occurrences and precisely correlated each event to the neogene geomagnetic polarity time scale thirteen of these events are based on revised taxonomic studies of the genera anthocyrtidium and pterocorys some events show significant departures from synchroneity five of the radiolarian first appearances and seven of the last appearances are time transgressive by 0 4 m y or greater we here propose a revised eleven fold radiolarian zonation for the pliocene pleistocene using zonal boundaries defined by events which are easily recognized and are demonstrably synchronous in the tropical indo paciflc the sequence of faunal and floral events reported in this paper will allow high resolution biostratigraphic correlations within the tropical indian ocean however the same sequence of events is not necessarily applicable to other tropical or extratropical regions