structure of fossil dinosaur eggshell from the aix basin france abstract at least four types of dinosaur eggshell are distinguished among samples of fossil eggshell from late cretaceous deposits of southern france recognition is based on shell microstructure porosity and shell thickness estimated values of water vapour conductance for these dinosaur eggshells are much greather than predicted for avian eggs suggesting that the eggs were incubated under conditions of high humidity such as would occur underground

diagenese differentielle chez les rongeurs fossiles validite des parametres geochimiques pour les reconstitutions des regimes alimentaires abstract the effects of diagenesis during sedimentation and fossilization on the chemistry of bones and teeth are rarely taken into account in quantitative paleoenvironmental reconstructions we demonstrate here that each present day tissue displays its own chemical composition moreover comparison between major and minor chemical contents between modern and fossil rodent skeletal elements through localized microanalyses further indicates the importance of the diagenetic factors alterations of the contents of chemical elements of fossilized tissues are found in comparison with recent ones and variability occurs from one tissue to the other and for different elements the tissue that is most modified by fossilization is the incisor dentine the most variable element is mg sr varies in bone while ca varies in all the tissues thus the reliability of using sr ca and mg ca ratios in paleodiets is discussed and their limits defined the necessity of localized analyses is here demonstrated as well as the importance of further investigations in diagenetic processes

turbulent mixing near the yermak plateau during the coordinated eastern arctic experiment during the ice camp component of the coordinated eastern arctic experiment cearex in march april 1989 1500 profiles of temperature conductivity and velocity shear microstructure were obtained near the yermak plateau the dominant signal in isopycnal displacements was the diurnal variability near the plateau consistent with the enhanced diurnal currents found in this region previously from the fram iii and fram iv ice camps the dissipation rate of turbulent kinetic energy e reached maximum values of about 10 6 w kg 1 in two distinct regions the surface mixing layer and the pycnocline between 120 and 220 m there was a significant component of diurnal variability in e in each region in the surface layer e was proportional to the cube of the ice relative current speed at 30 m below the ice and it decayed approximately exponentially with increasing depth major mixing events in the pycnocline were correlated with large amplitude short duration isopycnal displacements the lowest dissipation rates were recorded over the deep nansen basin north of the plateau and in the subsurface core of a submesoscale baroclinic eddy in northern fram strait the time averaged vertical eddy diffusivity near the slope of the plateau was about 2 5 10 4 m2 s 1 in the pycnocline above the atlantic layer implying an upward heat flux of 25 w m 2 although only a small fraction of this heat reached the base of the mixed layer the results confirm that current interactions with steep topography are critical to the modification of atlantic water in the eastern arctic ocean

turbulent heat flux in the upper ocean under sea ice turbulence data from three arctic drift station experiments demonstrate features of turbulent heat transfer in the oceanic boundary layer time series analysis of several w t records shows that heat and momentum flux occur at nearly the same scales typically by turbulent eddies of the order of 10 20 m in horizontal extent and a few meters in vertical extent probability distribution functions of w t have large skewness and kurtosis where the latter confirms that most of the flux occurs in intermittent events with positive and negative excursions an order of magnitude larger than the mean value an estimate of the eddy heat diffusivity in the outer ekman part of the boundary layer based on measured heat flux and temperature gradient during a diurnal tidal cycle over the yermak plateau slope north of fram strait agrees reasonably well with the eddy viscosity with values as high as 0 15 m2 s 1 an analysis of measurements made near the ice ocean interface at the three stations shows that heat flux increases with both temperature elevation above freezing and with friction velocity at the interface it also reveals a surprising uniformity in parameters describing the heat and mass transfer e g the thickness of the transition sublayer from a modified version of the yaglom kader theory is about 10 cm at all three sites despite nearly a fivefold difference in the under ice roughness z0 which ranges from approximately 2 to 9 cm a much simplified model for heat and mass transfer at the ice ocean interface suggested by the relative uniformity of the heat transfer coefficients at the three sites is outlined

the stable isotopic composition of modern soil carbonate and its relationship to climate the oxygen isotopic composition of modern soil carbonate is well correlated with the isotopic composition of local meteoric water the carbon isotopic cycle for co 2 in soils can be described in terms of the proportion of biomass using the c 4 photosynthetic pathway and the co 2 respiration rate of the soil at low soil respiration rates significant atmospheric co 2 mixing can occur in general the carbon isotopic composition of soil carbonate is related to the proportion of c 4 biomass present in soil but soils that freeze to the depth of carbonate formation often have a significant atmospheric component this suggests that freezing of the soil solution should be considered as another important mechanism for soil carbonate formation because of these relationships the isotopic composition of soil carbonate may be a paleoclimatic and paleoecologic indicator in cases in which diagenetic alteration has not occurred

use of multiple oxygen isotope proxies for elucidating arctic cretaceous palaeo hydrology stable oxygen isotope analysis of siderite and dinosaur tooth enamel phosphate from the campanian maastrichtian prince creek formation alaska usa are analysed to determine the palaeohydrology of the ancient colville basin north of the ancestral brooks range do of freshwater siderites relative to v pdb ranges between 214 86 and 216 21 dinosaur tooth enamel do from three different sites kikak tegoseak pediomys point liscomb range between 3 9 and 10 2 0 dometeoric water are calculated from dosiderite that formed at seasonal temperatures ranging from 22 to 14 5 8c with a mean annual temperature of 6 3 8c at 6 3 8c the dow calculated from siderite ranged between 222 23 and 220 89 v smow ingested water compositions are estimated from dinosaur teeth assuming body temperatures of 37 8c and local relative humidity of 77 5 resulting in values ranging from 228 7 to 220 4 v smow suggesting consumption of meteoric water and orographically depleted runoff from the brooks range the ranges in calculated dometeoric water are compatible between the two proxies and are mutually corroborating evidence of extremely o depleted precipitation at high latitudes during the late cretaceous relative to those generated using general circulation models this depletion is proposed to result from increased rainout effects from an intensified hydrological cycle which probably played a role in sustaining polar warmth supplementary material parameters used for generation of equations compared to kohn 1996 can be found at http www geolsoc org uk sup18642 stable isotopic proxies are invaluable tools for understanding past and current climates pedogenic carbonates siderite and calcite are commonly used to determine the isotopic composition of meteoric water lohmann 1988 hays grossman 1991 ludvigson et al 1998 ufnar et al 2004a suarez et al 2011 when analysed over a range of latitudes the resulting isotopic gradients can be used to determine global isotopic groundwater gradients this gradient is related to the isotopic composition of the precipitation which is itself related to temperature gradients humidity and in some instances orographic effects isotopic studies of the cretaceous are of particular importance because future climatic conditions kiehl 2011 are predicted to approach those pco2 temperature seen in the various greenhouse worlds of the cretaceous several studies on the cretaceous climate have revealed shallow equatorial topole air and ocean temperature gradients wolfe upchurch 1987 amiot et al 2004 jenkyns et al 2004 puceat et al 2007 while others have indicated equator to pole precipitation do gradients that are steeper than the modern climate system ludvigson et al 1998 ufnar et al 2002 suarez et al 2011 this steep gradient has been explained as resulting from increased rainout thereby increasing latent heat transport from the equator to the poles during greenhouse conditions ufnar et al 2004b these conclusions are based on empirical from bojar a v melinte dobrinescu m c smit j eds isotopic studies in cretaceous research geological society london special publications 382 http dx doi org 10 1144 sp382 3 the geological society of london 2013 publishing disclaimer www geolsoc org uk pub ethics by guest on june 17 2013 http sp lyellcollection org downloaded from

stable carbon isotope stratigraphy of the paleogene pedogenic series of southern france as a basis for continental marine correlation the upper cretaceous lower paleogene formations in the aix en provence basin are characterized by interfingering lacustrine carbonates and flood plain alluvium the deposits from both environments display numerous horizons of carbonate rich paleosols by using a combined magnetostratigraphy and carbon isotope stratigraphy for the pedogenic carbonate glaebules we constructed a detailed integrated stratigraphy for the entire lower paleogene this method provides a way to correlate marine and terrestrial sequences when c3 plants dominated the environment both long term and short term 13 c variations were identified in the provence series 1 the uniform carbon isotope record established through the end of the maastrichtian followed by the abruptly negative carbon isotope excursion in the lowermost paleocene provides a marker for the precise location of the cretaceous tertiary boundary in this basin 5 m below the calcaire de vitrolles formation 2 a gradual 13 c increase through the middle upper paleocene similar in amplitude to that of the marine realm 3 a short term negative 13 c excursion in the latest paleocene as seen within the calcaire de st marc formation and 4 a slow decrease during the late paleocene to early eocene with a probable hiatus in the sedimentary record the provence mammal site of palette is shown to be stratigraphically younger than the late paleocene negative 13 c excursion

systematic variations in the carbon and oxygen isotopic composition of pedogenic carbonate along elevation transects in the southern great basin united states stable carbon and oxygen isotope variations in holocene soil carbonates that formed in the unsaturated zone were examined along several elevation transects in the southern great basin united states a region with a semi arid climate our intent was to study the relationship between the stable isotopic composition of pedogenic carbonates and climate ecological variations differences in parent material and soil depth 13 c of pedogenic carbonate in three different soil profiles from different elevations decreases with soil depth indicating a decrease in the ratio of atmospheric to plantderived co 2 downprofile pedogenic carbonate at the soil air interface approaches a 13 c value in equilibrium with atmospheric co 2 in all three soils observed 13 c profiles for pedogenic carbonate can be described using a one dimensional model for 12 co 2 and 13 co 2 assuming isotopic equilibrium between soil co 2 and soil carbonate the modeled best fit to observed isotopic profiles suggests that the profile differences in part result from differing soil respiration rates at each site 13 c in deep pedogenic carbonate 50 cm varies by about 12 per mil over a 2 440 m elevation range being enriched in 13 c at the lowest elevations the slope of 13 c for these carbonates versus elevation is very similar for soils developed on carbonate and on noncarbonate parent materials depletion by 4 6 to 4 7 per mil per 1 000 m increase in altitude between 300 to 2 740 m above mean sea level for the localities studied this concordance makes it likely that there has been complete isotopic exchange between hco 3 in solution and soil co 2 prior to carbonate precipitation soil co 2 and soil respiration rates increase systematically with elevation the plantderived component of soil co 2 indicates that c 3 plants dominate the biomass at most measured sites in agreement with plant surveys calculated equilibrium fractionation factors between soil co 2 and soil carbonate are very similar to those observed again indicating complete isotopic exchange between carbon species in all the soil co 2 and soil carbonate data suggest that the 13 c variation with elevation observed in the soil carbonates results from differing soil respiration rates at each site as well as from variations in the proportion of c 3 to c 4 and cam plants in each site9s surface biomass 18 o values in pedogenic carbonates are higher at lower elevations due in part to the more positive 18 o values for meteoric waters at lower elevations the average 18 o value of deep 50 cm pedogenic carbonate at all sites however is enriched 2 4 to 3 7 per mil with respect to values we predict should be in equilibrium with the isotopic composition of local meteoric waters this suggests that evaporative isotopic enrichment of soil waters may have occurred at all elevations prior to precipitation of carbonate or that seasonal differences in the isotopic composition of meteoric waters coupled with differential infiltration may be taking place one or both of these processes also may explain the 18 o decrease in soil carbonate with depth observed in two of three soil profiles

groundwater dolocretes in a lake marginal environment an alternative model for dolocrete formation in continental settings danian of the provence basin france in the long continental history of the provence basin which extended from santonian to oligocene times a major period of palaeosol development occurred in the danian dolocretes developed within floodplain silts and partly from palustrine limestones dolocretes are overlain by pedogenic facies calcretes and palustrine limestones gradational lower and upper limits of profiles succession of nodular coalescent and massive horizons the epigenesis of quartz by dolomite the unimodal crystal size and the euhedral dolomite fabric as well as the absence of biogenic structures and vadose cements show that dolocretes formed in the phreatic zone the exclusive occurrence of dolocretes around the palaeolake or playa suggests that dolocrete formed by the mixing of groundwaters and lake brines which infiltrated the phreatic zone during periods of strong evaporation and lake level lowering the term halo dolocrete is proposed to describe this type of dolocrete deposit subsequent alteration of the dolocrete includes leaching of the central core of dolomite crystals and calcitization calcitization was either fabric destructive type i or fabric preserving type ii and took place during very early diagenesis i e concomitant with calcrete formation or palustrine limestone deposition fabric destructive calcitization is attributed to a drop in the lake level when the upper part of the dolocrete was subjected to vadose zone processes whereas the fabric preserving calcitization resulted from reactions with dilute lake and groundwaters during rise in lake level

cathodoluminescene at low fe and mn concentrations a sims study of zones in natural calcites abstract point analyses of natural calcite cements by sims confirm the earlier suggestions that 20 ppm mn is required to activate luminescence whereas fe concentrations in excess of 1400 ppm quench it partly independently of the mn content below this fe threshold luminescence is bright at mn concentrations in excess of 225 ppm in the range 20 225 mn all types of luminescence dull luminescent and nonluminescent can occur this undifferentiated domain is evident also from a compilation of literature data the type of luminescence is not a simple function of fe and mn concentrations other parameters influence cl sinc most diagenetic calcite cements have fe and mn concentrations that place them within the field of mixed cathodoluminescence these results force reassessment of models that equate the type of luminescence with the redox state of the diagenetic environment

mixing in the west spitsbergen current abstract twenty eight profiles of temperature and salinity down to 1 km depth have been measured in the area north from the coast of svalbard to latitude 84 40 n between 0 and 32 e longitude they show atlantic waters of the west spitsbergen current entering the arctic ocean in a bifilimentary mode one filament following the coastline and the other 300 km farther north apparently following the continental shelf break the profiles show these filaments mixing into the ambient water in a series of intrusive layers which are remarkably uniform over distances of hundreds of kilometers a triple peak structure at the atlantic water maximum is the dominant oceanographic characteristic of the area with salt fingering occurring on the upper surface of the cold intrusions and indications of double diffusive exchanges through the lower surface a system or eddies or meanders is postulated as the mechanism for the production of multiple fronts allowing the intrusive layers to extend to distances much greater t

role of the molecular sublayer in the melting or freezing of sea ice abstract in an earlier paper a second moment turbulence closure model was applied to the problem of the dynamic and thermodynamic interaction of sea ice and the ocean surface mixed layer an overly simplistic parameterization of the molecular sublayers of temperature and salinity within the mixed layer was used this paper investigates the use of a more recent parameterization by yaglom and kader which is supported by laboratory data a relatively low melt rate results in the case where ice overlays warm water this agrees with some recent observations in the interior of the marginal ice zone a surface heat sink drives the freezing case which due to the large difference in heat and salt molecular diffusivities produces a strong supercooling effect this is converted into an estimate of frazil ice production through a simple scheme the model results provide an explanation for high frazil ice concentrations observed in the arctic and antarctic

an investigation of barium calcium and strontium as palaeodietary indicators in the southwestern cape south africa samples of modern indigenous foods and archaeological human skeletons from the southwestern cape of south africa were analyzed for barium strontium and calcium barium strontium and barium calcium successfully differentiate marine and terrestrial foods measurement of all three elements improves the resolution of the marine terrestrial separation and enhances the trophic level differentiation analysis of the archaeological human skeletons indicates that removal of diagenetic contamination is critical in order to obtain useful elemental analyses where such removal is possible barium strontium and barium calcium techniques can be particularly valuable in distinguishing marine and terrestrial inputs into prehistoric human diets in areas where stable carbon analyses are not applicable e g in regions with terrestrial c 4 flora

contributions of the siberian shelf polynyas to the arctic ocean intermediate and deep water the role of the open water regions or polynyas in the winter ice pack over the siberian continental shelves in the production of arctic ocean intermediate and deep water is examined through use of a combination of passive microwave satellite data coastal weather station data and oceanographic data the satellite data allow us to derive a time series of the open water areas of selected polynyas for the 1978 1982 winters the polynyas which occur north of svalbard around franz josef land along the west coast and north end of novaya zemlya and to the east of severnaya zemlya and the taymyr peninsula are the primary oceanographic contributors the open water time series for these polynyas are used in combination with coastal weather station data to estimate the heat loss from each polynya for the region north of svalbard which is historically known as whalers bay the study shows that the heat loss is sufficient to provide the observed cooling of the west spitsbergen current for the other polynyas the heat loss is used to compute the ice production rates and the oceanic salt flux we then use the historic oceanographic salinities with the salt fluxes to estimate the contribution of each polynya to the arctic ocean water masses if we assume that the salt contributes only to the arctic intermediate water our results show that the shelves are capable of producing about 20 60 of this water alternatively if the salt contributes only to the deep water of the eurasian basin then without consideration of the mixing of the bottom water with the greenland and norwegian sea water the contribution from the shelves yields a renewal time of about 100 years our results imply that there is insufficient water produced in the shelf polynyas to perform all of the roles that have been historically assigned to it

on the origin of the chemical properties of the arctic ocean halocline profiles of chemical constituents in seawater above the alpha ridge in the central arctic ocean obtained during the canadian expedition to study the alpha ridge cesar support a model in which the halocline is maintained by dense saline water produced on the continental shelves within the arctic ocean by the formation of sea ice it is argued that nutrient regeneration on the continental shelves largely accounts for the nutrient maximum that has been observed in the upper halocline over a wide region of the arctic ocean and that while the bering sea and north altantic can be recognized as origins of halocline water water masses from these regions undergo sufficient changes in their chemical properties within the arctic ocean significant that they no longer retain their identity in the halocline

holocene environments of the central great plains multi proxy evidence from alluvial sequences southeastern nebraska abstract pollen plant macrofossils phytoliths carbon isotopes and alluvial history from sediments exposed along the south fork of the big nemaha river southeastern nebraska usa provide an integrated reconstruction of changes in holocene vegetation climate and fluvial activity from 9000 to 8500 uncalibrated 14 c yr bp climate became more arid and the floodplain and alluvial fans in the main valley aggraded rapidly upland deciduous forest declined and prairie attained its holocene dominance from 8500 to 5800 yr bp upland forest elements disappeared and even riparian trees were sparse under dry climatic conditions alluvial fans continued to aggrade but aggradation in the main valley was interrupted by a stable episode 7000 yr bp from 5800 to 3100 yr bp riparian forests returned to prominence and droughts were intermittent alluviation was slower and punctuated by two major episodes of channel incision and terrace formation in the main valley aggradation on alluvial fans slowed and finally ceased near the end of this period during a short dry interval from 3100 to 2700 yr bp riparian trees except elm disappeared and prairie and weedy species became more abundant this interval is represented by the organic roberts creek member and the alluvial setting was a slightly incised meandering channel belt habitats became similar to presettlement conditions during the last 2700 yr bp weedy taxa dominate modern samples reflecting widespread disturbance alluvial fans and terrace surfaces were stable during the last 2500 years but episodes of floodplain aggradation were punctuated by incision of the main channel

distribution of convective lower halocline water in the eastern arctic ocean 1 we investigate the distribution of convectively formed lower halocline water clhw in the eastern arctic ocean using observational and climatological data the clhw can be defined as the water mass in the cold halocline layer formed by winter convection the presence of clhw is indicated by temperatures close to the freezing point and a sharp bend in the s curve near the salinity of clhw results from ice drifting buoy observations in 2002 show differences in water mass characteristics in the upper ocean among the amundsen basin over the arctic mid ocean ridge and in the nansen basin in 2000 2002 clhw was present over the arctic mid ocean ridge and the nansen basin but was largely absent from the amundsen basin using climatological data we find that clhw was confined to the nansen basin prior to 1990 in the early 1990s clhw still covered only the nansen basin but extended to the northern side of the arctic mid ocean ridge in the mid 1990s and covered the whole of the amundsen basin by the late 1990s in the early 2000s the area of clhw moved back to its present boundary on the northern side of the arctic mid ocean ridge these results correspond roughly to other changes in the arctic ocean circulation and water mass structure but with a time delay we hypothesize that general circulation changes and the cutoff of source water for advective convective modification of the lhw are causes of the change in clhw distribution the lag in changes to clhw distribution behind other changes in the atmosphere and upper ocean are likely related to differences in circulation change with depth and the transit time from clhw formation

two circulation regimes of the wind driven arctic ocean the major goal of this paper is to demonstrate the existence in the arctic ocean of two regimes of wind forced circulation we simulated the vertically averaged currents sea level heights and ice drift in the arctic ocean from 1946 to 1993 using a two dimensional wind forced barotropic model that includes frictional coupling between the ocean and ice the model has a spatial resolution of 55 5 km and is driven by winds river runoff and an imposed but realistic sea level slope between the pacific and the atlantic oceans there is a good agreement between velocities from observed buoy motions and velocities of modeled ice drift even though the model lacks ocean baroclinicity and ice thermodynamics the results indicate that wind driven motion in the central arctic alternates between anticyclonic and cyclonic circulation with each regime persisting for 5 7 years based upon our analysis of the modeled sea level and ice motion anticyclonic wind driven motion in the central arctic appeared during 1946 1952 1958 1963 1972 1979 and 1984 1988 and cyclonic motion appeared during 1953 1957 1964 1971 1980 1983 and 1989 1993 shifts from one regime to another are forced by changes in the location and intensity of the icelandic low and the siberian high the two regimes may help explain the significant basin scale changes in the arctic s temperature and salinity structure observed recently the great salinity anomaly and the variability of ice conditions in the arctic ocean

freshwater balance and the sources of deep and bottom waters in the arctic ocean inferred from the distribution of h218o data from sections across the eurasian basin of the arctic ocean occupied in 1987 and 1991 are used to derive information on the freshwater balance of the arctic ocean and on sources of the deep waters of the nansen amundsen and makarov basins using salinity h218o and mass balances we estimate the river runoff and the sea ice melt water fractions contained in the upper waters of the arctic ocean and infer pathways of the river runoff signal from the shelf seas across the central arctic ocean to fram strait the average mean residence time of the river runoff fraction contained in the arctic ocean halocline is determined to be about 11 to 14 years pacific water entering through bering strait is traced using silicate and its influence on the halocline waters of the canadian basin is estimated water column inventories of river runoff and sea ice melt water are calculated for a section just north of fram strait and implications of these inventories for sea ice export through fram strait are discussed comparison of the 18o 16o ratios of shelf water atlantic water and the deep waters of the arctic ocean indicate that the sources of the deep and bottom waters of the eurasian basin are located in the barents and kara seas

ice seawater turbulent boundary layer interaction with melting or freezing abstract a second moment turbulence closure model is applied to the problem of the dynamic and thermodynamic interaction of sea ice and the ocean surface mixed layer in the case of ice moving over a warm ocean surface layer melting is intrinsically a transient process that is melting is rapid when warm surface water initially contacts the ice then the process slows when surface water is insulated from deeper water due to the stabilizing effect of the melt water and the thermal energy stored in the surface layer is depleted effectively the same process prevails when ocean surface water flows under stationary ice in which case after an initial rapid increase the melting process decreases with downstream distance accompanying the stabilizing effect of the melt water is a reduction in the ice seawater interfacial shear stress this process and model simulators are used to explain field observations wherein ice near the marginal ice zone diverges from the main pack when the surface ice layer is m

physical and geochemical properties across the atlantic pacific water mass front in the southern canadian basin temperature salinity nutrients oxygen and halocarbon data collected in the arctic ocean reveal a frontal structure previously unrecognized in the hydrography of the canadian basin samples were collected on a 1300 km section extending from the beaufort sea in the canada basin to the east siberian sea in the makarov basin these data collected in 1993 aboard the ccgs henry larsen reveal a lateral boundary between water masses of atlantic and pacific origin the term water mass assembly is introduced to describe the basic arrangement or vertical stacking of water masses found in the arctic ocean recognizing that water mass components within each assembly may differ from basin to basin using historical data two primary water mass assemblies are defined each consisting of three layers an upper layer an atlantic layer and a deep layer these two assemblies are marked by important differences one assembly here defined as the western arctic wa assembly is characterized by an upper layer of relatively fresh high nutrient water of pacific origin below this by an atlantic layer with a core temperature generally below 0 5 c and finally by a deep layer of higher salinities and colder temperatures about 0 5 c than found in the overlying atlantic layer the second assembly here defined as eastern arctic ea assembly is characterized by the absence of pacific water in the upper layer below this by an atlantic layer core as warm as 2 to 3 c and by a colder about 0 9 c deep layer because the presence or absence of pacific origin water is a key characteristic distinguishing the two assemblies we will refer to the water mass boundary between the two assemblies as the atlantic pacific front earlier research indicated that water masses in the arctic ocean were separated by a front above the lomonosov ridge into the canadian and eurasian basins although all larsen 93 stations from the canada basin a1 d1 display classic wa assembly characteristics the makarov basin station e1 shows ea assembly characteristics in the upper and atlantic layers and a wa assembly deep layer this suggests a relocation in the position of the atlantic pacific boundary away from the lomonosov ridge further larsen 93 data show the transition region between the atlantic and deep layers is fresher in the makarov basin than corresponding water in either the canada or eurasian basins implying a source of cold low salinity water perhaps from the laptev and east siberian shelves the front separating these two assemblies lies above the mendeleyev ridge and is marked by large lateral gradients in all measured properties in particular the penetration of anthropogenic halocarbons is 2 to 3 times deeper in the makarov basin than in the canada basin implying enhanced rates of ventilation this suggests that direct exchange between the canadian and eurasian basins has occurred recently near the perimeter and that physical and chemical properties including contaminants may have been transported by boundary currents more quickly from one basin to the other

water masses and circulation in the eurasian basin results from the oden 91 expedition the oden 91 north pole expedition obtained oceanographic measurements on four sections in the nansen and amundsen basins of the eurasian basin and in the makarov basin of the canadian basin thereby proving the feasibility of carrying out a typical oceanographic program using an icebreaker in the arctic ocean the data show greater spatial variability in water structure and circulation than was apparent from previous data the results show that a clear front exists between the eurasian and canadian basins such that upper halocline water in the canadian basin is almost absent from the eurasian basin the lower halocline water produced in the barents kara sea region permeates much of the eurasian basin and flows along the continental slope into the canadian basin the deeper circulation is strongly influenced by topography three return flows of the atlantic layer are identified one over the nansen gakkel ridge one over the lomonosov ridge and a third flowing from the canadian basin the slight differences observed in salinity and temperature characteristics of the deeper waters of the nansen and amundsen basins do not lead to an obvious explanation of their origin or flow pattern

did the european dinosaurs disappear before the k t event magnetostratigraphic evidence abstract debate on the non catastrophic or catastrophic extinction of the dinosaurs by an asteroid impact k t event remains a controversy and is mainly based on the interpretation of the sedimentary continental sequences in the north american western interior the global aspect of this event needs to be tested in sedimentary record from all continents where continuous terrestrial deposits through the cretaceous paleogene are well preserved in the western mediterranean realm recognition of the cretaceous paleogene boundary is limited by the lack of biostratigraphic data in the upper cretaceous lower tertiary continental sedimentary sequences new magnetostratigraphic results were obtained from the analysis of two sections in southern france and compared to previous results in northern spain the last occurrence of in situ dinosaurs eggshells the only dinosaur remains found is located in chron 30n southeast france or 31n southwest france and northern spain this last occurrence could demonstrate that the extinction of the european dinosaurs occurred prior to the cretaceous paleogene boundary and would therefore support the idea of a gradual or stepwise extinction unlinked to the k t event

dinosaur egg bearing deposits upper cretaceous of boseong korea occurrence palaeoenvironments taphonomy and preservation abstract dinosaur sauropod and ornithopod egg bearing deposits of the upper cretaceous seonso conglomerate boseong korea were examined sedimentologically for palaeoenvironmental and preservational interpretation dinosaur eggs are commonly preserved as clutches although isolated eggs also occur the clutches are found in at least six horizons consisting of sandy mudstones to mudstones these strata are interpreted as terminal fan deposits calcite rims and calcite aureols around detrital grains pedotubular to nodular calcretes and circumgranular to circumnodular cracks are present in the dinosaur egg deposits these features indicate calcareous pedogenesis which appears to have assisted in the preservation of the eggs in one egg deposit in which clutches are mostly found vertic features including pedogenic slickensides pseudoanticlines and calcite filled deep desiccation cracks occur the preservation of these dinosaur eggs in calcic and vertic palaeosols suggests that the palaeoclimate of the nested area was semiarid the lack of displacement of eggs and egg shells the presence of some egg clutches 5 10 cm below flood deposits and the porous nature of the eggshells suggest that the eggs were laid in excavated nests that were buried during incubation the preservation of numerous dinosaur clutches in several horizons at boseong is consistent with site fidelity

diagenetic changes in the mineral and organic phases of fossil avian eggshells from namibia recent surveys in the neogene aeolianites of the namib sand sea have led to the recovery of abundant and varied fossil eggshell fragments from diverse stratigraphic horizons aepyornithoid struthio and diamantornis the mineralogy elemental composition and organic matrices of these eggshells have been studied despite good preservation of the microstructural and mineralogical features of the fossil eggshells the organic matrices have been altered in quantity and quality the soluble and insoluble matrices of the eggshells show different behaviour during diagenetic processes

dinosaur bones fossils or pseudomorphs the pitfalls of physiology reconstruction from apatitic fossils abstract a prerequisite to any attempt to reconstruct thermophysiology of ancient animals through analysis of stable isotopes of oxygen is the assumption that apatitic fossils are isotopically unaltered parts of their original skeletons we suggest that sufficient evidence is available to seriously question this assumption because living bones contain about 1 3 by weight of organic matrix mass balance considerations show that at least half of an apatitic fossil must be new material added post mortem furthermore living apatitic skeletons contain almost no rare earth elements and uranium whereas apatitic fossils bear high concentrations of these elements additionally we found that while in living fish correlation between 18o of oxygen in the phosphate and that in the carbonate of apatite is poor these two values are linearly correlated in fossil fish this suggests diagenetic recrystallization has taken place perfect preservation of micro textures such as haversian canals does not prove the pristine condition of a fossil some of the most beautifully preserved fossils are highly silicified most apatitic fossils probably are pseudomorphs replacing original skeletal elements whereas distribution of stable isotopes of oxygen in fossils might provide information about their burial environment it could be misleading in attempts to interpret the organisms physiology this cautionary note is supported by the similarity of 18op in bones of coexisting fossil fish dinosaurs and various other reptiles at different latitudes the overlap of predicted 18op values in fish and mammals living in contact with the same environmental water also weakens the hope that ectotherms can be distinguished from endotherms by the isotopic composition of oxygen in their bones and teeth

preservation of titanosaur egg clutches in upper cretaceous cumulative palaeosols los llanos formation la rioja argentina abstract studies of the palaeobiology of titanosaur eggs are significantly more common than studies of titanosaur egg bearing strata nevertheless the latter provide significant insight into palaeoenvironmental conditions associated with the egg laying behaviour this study examines titanosaur egg bearing strata of the upper cretaceous los llanos formation la rioja argentina and relates them to the laying and preservation of titanosaur egg clutches los llanos formation is a predominantly sandstone succession throughout represented by palaeosol profiles five titanosaur egg clutches were recovered from the bw horizon of an inceptisol profile this palaeosol type named tama pedotype constitutes 69 of the entire succession by thickness rare planar and undulating lamination and cross stratification quartz grain surface microtextures and ventifacts are indicative of the interaction of fluvial aeolian processes of sedimentation during accumulation of the parent material on the distal part of a coalescent alluvial fan system bajada highly abundant root traces reddish colour clay coatings and calcium carbonate nodules testify that the tama pedotype had abundant vegetation cover and was developed in well drained conditions under the influence of a semiarid climate regime palaeosol horizons with exaggerated thickness and diffuse boundaries indicate a cumulative pedotype whereby the soil developed in response to continuous accretion via on going sedimentary processes morphological features of eggshells suggest that titanosaurs dug holes in the topographic surface to lay eggs thus palaeosols seem to have been putative areas for the laying of titanosaur eggs actually it is uncommon for palaeosols to constitute sites for the preservation of eggs since soils typically develop in response to long episodes of weathering however cumulative palaeosols can provide ideal conditions for egg burial and preservation in cumulative soils the residence time of an object within the weatherable thickness of a soil is reduced to 3 years thereby significantly increasing the long term preservation potential of eggs

an estimate of the mean field of arctic sea ice motion the observational basis for our understanding of sea ice motion comes from the trajectories of particular ice floes these ice floes may have been marked by a manned research station or more recently by an automatic data buoy since 1893 almost 100 station years of drift data have been recorded using the principles of optimal linear estimation these data are used to obtain a quantitative estimate of the field of mean motion

dinosaur eggshells as biochronological markers in upper cretaceous continental deposits abstract european dinosaur eggshells are now well organized in a parataxonomic classification and can be used as reliable biochronological markers for upper cretaceous continental deposits the rognacian campanian maastrichtian continental deposits of southern france can be divided into three successive associations of megaloolithidae taxa a maximum in ootaxa diversity occurs in upper campanian deposits followed by a decrease at the campanian maastrichtian transition this correlates with a climatic change recorded in the palynological floras the stratigraphic distribution of the oospecies demonstrates that the rognac limestone found in the west and east areas of the arc basin is diachronic

dense water formation in the laptev sea flaw lead 1 two primitive equation based models are used to estimate the formation of total volumes either of arctic cold halocline water chw intermediate water imw or deep water dw through freeze related salt rejection in the siberian laptev sea flaw lead system model a assumes that the rejected salt remixes with surface mixed water smw beyond the leads until salinities allow for contribution to the midlayers of either the chw the imw or the dw model b simulates direct salt rejection to the upper layer of the cold halocline and after remixing here further contribution to the midlayers of chw imw or dw averaging both model estimates laptev leads contribute either 0 161 sv of chw 0 075 sv of imw or 0 065 sv of dw which represents as much as 23 16 or 30 of arctic wide lead derived dense water contribution to the appropriate layer respectively northwestern laptev leads produce the greatest amount of dense water these lead sections show very short buoyancy equilibrium timescales 6 to 13 days and local dense water production may potentially be amplified by lateral brine injection into the cold halocline through bottom eddies central southern and southeastern leads generally produce little salt due to low surface water salinities as definite separation mechanisms and proportion distributions of rejected lead brines into chw iwm and dw are still unidentified in nature a combination of lead salt rejection and remixing model a and direct downward expulsion of brine packages model b is assumed to steer laptev lead dense water production

depositional setting and early diagenesis of the dinosaur eggshell bearing aren fm at bastus late campanian south central pyrenees the late cretaceous aren fm exposed north of bastus in the tremp basin south central pyrenees preserves an excellent record of dinosaur eggs laid in a marine littoral setting different from other cases reported in literature at the bastus site the preferential nesting ground was original beach sand the coastal deposits of aren fm can be grouped into four facies assemblages representing respectively shoreface beachface beach ridge plain and backbarrier lagoon environments shoreface deposits include fine to coarsegrained hybrid arenites and subordinate quartz dominated conglomerates with ripple structures of wave and wave current origin beachface deposits are mainly storm beach conglomerates but parallel laminated foreshore arenites locally occur backbarrier lagoon deposits comprise of washover sandy conglomerates that grade laterally into sandy lime mudstones biomicrites and marls beach ridge sediment wherein the bulk of dinosaur eggs and eggshell debris occurs predominantly is a reddish hybrid arenite that has undergone a complex early diagenetic evolution including marine and meteoric cementation followed by soil development the reddish arenites overlie wave dominated shoreface deposits and in places pass laterally into lagoonal deposits they originally formed shore ridges that became stabilized during progradational episodes by pedogenesis beach ridge sensu otvos e g 2000 beach ridges definitions and significance geomorphology 32 83 108 which also affected the dinosaur eggs the eggshell bearing beach ridge arenites are typically preserved at the top of parasequences forming the systems tracts of a third order sequence thick packages of this facies resulted from aggradation of barrier beach ridge deposits whose preservation below surfaces of transgressive erosion was favoured by incipient lithification

geochemical profiles in the central arctic ocean their relation to freezing and shallow circulation temperature salinity nutrient tritium and oxygen isotope data collected during the lomonosov ridge experiment along a drift track between the makarov and fram basins over the lomonosov ridge are presented the relationship of these quantities to the processes that maintain the halocline in particular to the production of more saline waters by addition of brines formed during the freezing of seawater is described the results support the idea that the wide continental shelves of the arctic ocean play an important role in maintaining the halocline productivity and to the chemical and physical effects of freezing sea water a comparison of this ocean with its low productivity at least during winter with other oceanic regions should help to elucidate some of the effects of biological activity on marine chemistry for example trace metal cycling and speciation aagaard et al 1981 discussed the way in which the cold waters of the halocline which lie immediately below the surface mixed layer and extend to the top of the warm atlantic layer could be produced on the wide continental margins surrounding the arctic ocean the processes in volve freezing with release of highly saline brines having a temperature close to the freezing point of surface sea water this water flows over the shelves and into the central basin sinking then to the appropriate density surface the distribu tions of various chemical parameters will be affected in predictable ways by these processes as a part of the lomonosov ridge experiment lorex which ran from late march until the end of may 1979 a program was undertaken aimed at describing more accurate ly the hydrography of the central arctic ocean and studying the geochemistry of selected trace elements in this unusual environment to this end water samples were collected from a drifting ice station lorex satellite camp 1 for the measurement of salinity silicate phosphate 5 80 trace metals moore 1981 1983 carbon 14 tritium helium 3 caesium 137 caesium 134 strontium 90 plutonium ameri cium h d livingston et al manuscript in preparation 1983 alkalinity and ph ice cores were collected to investi gate the possibility of deducing the extent of temporal changes in the tritium content of the surface waters

boundary undercurrent and water mass changes in the lincoln sea oceanographic measurements taken between 1989 and 1994 in the lincoln sea describe the currents and water mass structure along the continental slope of the arctic basin between the canadian and eurasian basins the measurements included periodic conductivity and temperature versus depth ctd profiles from ice camps ctd cross sections normal to the slope and year round current measurements analysis of this data describes the hydrographic structure of the waters over the continental slope and identifies some significant interannual variations an undercurrent confined to the continental slope with a width of about 50 km and speeds of 5 9 cm s 1 is shown in geostrophic current cross sections the presence of this easterly flow at depth is confirmed by current meter measurements and its existence has also been observed in the beaufort sea and the barents sea aagaard 1989 the waters within this undercurrent exhibit temperature salinity ts characteristics similar to canadian basin waters suggesting a boundary current system which is continuous along the continental slope north of alaska and canada significant interannual variations in temperature and salinity profiles may be related to variations in the large scale circulation of the arctic examination of the upper pycnocline waters over the slope between 1991 and 1994 indicated a relative temperature maximum overlying a minimum ts characteristics similar to waters attributed to bering sea origin found in the canadian basin these characteristics were not seen however during 1989 and 1990 suggesting a recent increase in the transport of surface waters from the canadian basin into the eurasian basin

stable isotope analyses of dinosaur eggshells paleoenvironmental implications well preserved clutches of dinosaur sauropod eggshells and skeletal remains have been discovered in the upper cretaceous lameta limestones of the kheda district gujarat india indicating a dinosaur nesting site oxygen isotope analyses of the eggs show that the dinosaurs drank from a variety of freshwater bodies such as rivers and small evaporative pools whereas the carbon isotope values indicate that the reptiles were consuming plants that utilize the c 3 photosynthetic pathway e g small palms shrubs conifers etc similar analyses of the host limestones suggest that they were deposited in a freshwater environment that provided the niche for large scale breeding and nesting of the dinosaurs

halocline water formation in the barents sea hydrographic data from the first phase of the coordinated eastern arctic experiment cearex are analyzed the data consist of temperature and salinity measurements made by a ship based conductivity temperature depth ctd instrument and by a drifting salargos buoy these data were collected in the autumn and early winter of 1988 1989 in the northern barents sea mostly in ice covered conditions and then across the marginal ice zone miz the data show that relatively warm salty water of atlantic origin is modified by air cooling and ice melting to produce lighter water that has properties identical to lower halocline water found in the arctic ocean this occurs mostly at the miz and to a lesser degree within the ice pack itself at the miz the halocline water subducts underneath the lighter meltwater that resides directly under the ice pack geostrophic velocity calculations indicate that it then turns eastward and flows toward the kara sea in keeping with previous chemical tracer analyses a rough calculation reveals that the amount of halocline water formed in this way in the barents sea and fram strait is 30 50 of that formed by ice growth in eastern arctic polynyas

hydrography of the west spitsbergen current svalbard branch autumn 2001 1 the atlantic inflow is the primary source of water and heat to the arctic ocean a large portion enters through fram strait where it splits into the yermak and svalbard branches in october to november 2001 the uscgc healy occupied five oceanographic transects across the svalbard branch west and north of spitsbergen temperature and salinity sections show the warm salty atlantic water cooling and freshening as it flows along the continental slope for 553 km the temperature in the upper 500 m of the water column decreased by 0 25 c 100 km implying a heat flux across the sea surface of up to 520 w m2 if one assumes a nominal current of speed of 0 1 m s a temperature salinity t s analysis shows that the shape of the t s curves can be explained in terms of the ratio of the atmospheric to ice melt heat flux the observations imply that ice melt accounts for progressively more surface cooling as the flow moves toward the arctic ocean an autonomous underwater vehicle completed a vertical section in the region of maximum water mass gradient and revealed layer interleaving in fine detail data from this cruise extend a long time series of atlantic layer source temperature beginning in 1910 saloranta and haugan 2001 the extended observations show that after the temperature of the atlantic layer inflow reached a peak in 1992 it cooled to a minimum in 1998 and rose again through 2001

stratigraphy of the paleocene continental sedimentary succession of the northern pyrenean basin corbieres southern france using δ13corg isotopes continental dominated successions are often poorly constrained stratigraphically due to a lack of robust biostratigraphic markers this study provides the first dataset of 13corg together with magnetostratigraphic and biostratigraphic data from a thick continental dominated succession at lairiere northern pyrenees france this section encompasses the latest cretaceous up to the paleocene eocene thermal maximum interval and is characterized by fluvial deposits occasionally intercalated with continental carbonates lacustrine deltaic deposits and shallow marine sediments this work identifies 13corg events and assigns them to global 13c geochemical events defined in pyrenean and tethyan marine successions in which the stage boundaries are well calibrated as the isotopic measurements are performed on dispersed organic matter in sedimentary rocks with a low organic content we propose that analyses of the signal should take into consideration the depositional environment because variations in the organic matter content might affect the signal we establish a high resolution chronostratigraphy in terrestrial paleocene deposits in the ne pyrenean zone recognize a late selandian interval and define the paleocene eocene thermal maximum event supplementary material palaeomagnetic results geochemistry details and palynological analysis are available at https doi org 10 6084 m9 figshare c 4871214

on the ice and heat balance in fram strait the sea ice margin northwest of spitsbergen is schematically represented by a stationary wedge maintained by opposing ice and warm atlantic water advection ice melt and cooling of the surface water generate a mixed layer with properties approximating those found elsewhere in the arctic basin the heat energy required to melt the advancing ice is roughly comparable to the rate of heat loss of the west spitsbergen current and suggests that direct heat exchange with the atmosphere is less important only a small fraction of the nearly fresh water from ice melt exits through eastern fram strait and most of it appears to return to the arctic basin whether or not it contributes to the formation and maintenance of the arctic mixed layer depends on the largely unknown circulation pattern north of fram strait an example of the large interannual variation of the mean wind stress field is shown to illustrate the likelihood of an equally large variance of the ice and surface water circulation

retreat of the cold halocline layer in the arctic ocean we present a comparison of arctic ocean hydrographic data sets from the 1990s with a focus on changes in the upper few hundred meters of the eurasian basin the most recent observations discussed here were collected during the spring 1995 scientific ice expedition scicex 95 the second in a series of scientific cruises to the arctic ocean aboard u s navy nuclear submarines although the 1990s have seen an abundance of synoptic cruises to the arctic this was the only one to take place in winter spring conditions other data considered here were collected during the first scicex cruise in summer 1993 scicex 93 and during an icebreaker cruise to the eurasian basin in summer 1991 oden 91 a new russian american winter climatology is also used as a reference these comparisons reveal that the eurasian basin cold halocline layer has retreated during the 1990s to cover significantly less area than in previous years specifically we find a retreat from the amundsen basin back into the makarov basin the latter is the only region with a true cold halocline layer during scicex 95 changes are also seen in other halocline types and in the atlantic water layer heat content and depth since the cold halocline layer insulates the surface layer and thus the overlying sea ice from the heat contained in the atlantic water layer this should have profound effects on the surface energy and mass balance of sea ice in this region using a simple mixing model we calculate maximum ice ocean heat fluxes of 1 3 w m 2 in the eurasian basin where during scicex 95 the surface layer lay in direct contact with the underlying atlantic water layer the overall cause of water mass changes in the 1990s might have been a shift in the atmospheric wind forcing and resulting sea ice motion during the late 1980s which we speculate influenced the location where fresh shelf waters flow into the deeper basins of the arctic ocean finally we discuss two different mechanisms that have been proposed for cold halocline water formation and we propose a compromise that best fits these data

stable isotope distribution in maastrichtian vertebrates and paleosols from the haţeg basin south carpathians abstract located in the south carpathians in romania the ha eg basin contains a thick sequence of maastrichtian continental deposits yielding a rich dinosaur and mammalian fauna stable isotope analyses of both calcretes and dinosaur crocodilian and turtle remains from two localities tustea and sibisel were integrated in order to reconstruct environmental conditions during maastrichtian time and to gain further insights into the metabolism and behaviour of the vertebrates the large difference observed between the 18o and 13c of the eggshells and the surrounding mudstones as well as the preservation of the 9 difference between the oxygen isotope composition of the telmatosaurus eggshell and tooth enamel indicate that diagenesis has not significantly altered the primary isotopic signal the presence of smectite in the fraction less than 2 m and the preservation of dinosaur eggshell structure also indicate that diagenesis was not significant in the studied outcrops stable isotope compositions of both calcretes and phosphatic remains suggest warmer conditions during the deposition of the tustea sequence mean annual temperature of around 14 c than during the deposition of the sibisel sequence mean annual temperature of 10 c the intra tooth 18o patterns for zalmoxes and allodaposuchus show different magnitudes of isotopic variation with lower values for tustea and higher for sibisel the calculated 18obody water enrichment for kallokibotion bajazidi is similar to that found in living turtle taxa by contrast in the case of allodaposuchus the isotopic enrichment is higher than for recent taxa this suggests that for allodaposuchus the body water was less buffered by a watery environment which probably indicates more time spent outside water i e more terrestrial habit the 18o values for the teeth of telmatosaurus and zalmoxes are similar to those of allodaposuchus suggesting that at the investigated sites the body temperature of both dinosaurs was similar to that of the crocodile the isotopic composition of calcretes teeth and eggshells indicates a c3 vegetation and diet with 13c values between 27 and 29 pdb and the absence of large scale habitat partitioning between the dinosaurs

waters of the makarov and canada basins abstract hydrographic measurements from the 1994 arctic ocean section show how the makarov and canada basins of the arctic ocean are related and demonstrate their oceanographic connections to the eurasian basin the inflow into the makarov basin consists largely of well ventilated water within a broad band of densities from a boundary flow over the siberian end of the lomonosov ridge the boundary flow contains a significant component of dense shelf water likely originating in the barents kara and laptev seas earlier ice camp data show that the canada basin is relatively more isolated from this ventilation source in the canada basin shelf sources influenced by bering sea water appear to add cold waters with high silicate concentrations to the halocline and deeper in 1994 the halocline silicate maximum over the central makarov basin was absent evidence of the recent displacement of the upper s 33 1 halocline water from the chukchi east siberian sea region by water from the eurasian basin much of the makarov basin water in and below the halocline is in fact from the eurasian basin with admixture of waters from the canada basin suggested by their higher silicate concentrations mid depth eddies may transport anomalous properties into the central arctic and create property gradients or fronts in mid depth and deep waters the complex topography of the mendeleyev ridge chukchi plateau region also may assist spreading of water from the boundary into the interior atlantic layer characteristics in 1994 differed from previous general depictions in particular the core temperatures at the chukchi mendeleyev boundary were at least 0 2 c warmer on average than indicated in earlier work the recent warming at intermediate depth has resulted from inflow of atlantic waters that have been cooled relatively little during their transit of the norwegian sea

dinosaur eggshell and tooth enamel geochemistry as an indicator of mongolian late cretaceous paleoenvironments the late cretaceous fossiliferous beds of mongolia s gobi desert have yielded spectacular articulated remains of a remarkable diversity of fossil mammals lizards turtles birds and non avian dinosaurs paleoenvironmental interpretations of the deposits at these localities have ranged from arid wind blown dune fields to more mesic moist environments among the diversity of fossils dinosaur eggshells and teeth are commonly found at these localities dinosaur eggs like modern avian eggs are constructed of biomineralized calcite caco3 and proteins allowing carbon and oxygen stable isotopes to be quantified to provide information about the environment in which the egg laying animals were living here it is shown that dinosaur eggshell and teeth from the djadokhta and nemegt formations have not been significantly altered and reflect an environment of dry dunes during deposition of the djadokhta formation and a more mesic stream environment for conditions in the nemegt formation carbonate nodules from the same eggshell bearing layers also independently reflect a similar environmental signal this study represents the first geochemical analysis of dinosaur remains from the cretaceous of mongolia and illustrates the potential of utilizing dinosaur fossil geochemistry of both eggs and teeth to reconstruct mesozoic environments

hydrography and vertical fluxes of heat and salt northeast of svalbard in autumn temperature and salinity data collected by a salargos buoy during october 1988 northeast of svalbard norway as part of the coordinated eastern arctic research experiment are analyzed as the buoy drifted across the continental slope the data show a transition from central arctic conditions where the thermocline lies below the halocline to shelf conditions where the two coincide surface waters on the shelf were above the freezing point losing heat to sea ice advected southward by the wind the atlantic inflow current was also observed on the continental slope with a maximum temperature above 3 c a storm caused upwelling and entrainment of this current leading to strong ice ocean heat fluxes and ice melting the resulting flux of fresh water stabilized the surface layer and shut off further entrainment this episodic process can lead to bigger heat losses from the atlantic inflow current than previously considered for ice covered conditions

palaeoenvironmental reconstruction of dinosaur nesting sites based on a geochemical approach to eggshells and associated palaeosols maastrichtian provence basin france variability of the stable isotopic n 13 c and n 18 o and trace element mg sr fe and mn content from dinosaur eggshells from the provence basin has been addressed by considering the stratigraphic distribution of the eggshells the palaeoenvironments and the chemical content of associated sediments preferentially in situ eggshells were analysed samples were collected from two sections one belonging to the floodplain roques hautes and the other to the channel belt rousset breguie res as determined from sedimentological criteria on a regional scale this combined analysis provided new insights into palaeohydrology vegetation cover and dinosaur behaviour different sources of drinking water were identified 1 the main stream waters with significant salinity levels 2 lateral feeders with water composition close to that of precipitation water composition is reflected in the eggshell trace element contents a high sr content for the eggshells from the channel belt mean 1200 ppm contrasting with the very low values for the floodplain mean 250 ppm during the first part of the maastrichtian evaporation rates were quite significant as seen from the 1 5x difference between the eggshell n 18 o drinking water and the palaeosol carbonate nodules precipitation this contrast diminished and became nearly insignificant in the second half of the maastrichtian vegetation was composed of c3 plants and two ecosystems are reconstructed a riparian forest extending along the channel belt and open vegetation in the floodplain the contrasted isotopic and trace element content of the eggshells was a crucial factor in identifying animal migration from one site to another migration was quite limited suggesting that the animals settled for some time at the places where they laid their eggs intraspecific variations among modern birds are well correlated with the environment and may be greater than interspecies variations which limits the potential of geochemical analysis to characterise dinosaur species 2002 elsevier science b v all rights reserved

reconstructing the paleotopography of mountain belts from the isotopic composition of authigenic minerals the paleorelief of mountain belts can be estimated from the 18 o value of authigenic minerals development of relief during mountain building often creates lee side rain shadows in which precipitation is depleted in 18 o and d the magnitude of this rain shadow effect is strongly correlated to relief a compilation of 18 o data from surface waters throughout the globe shows a linear relationship between net elevation change and 18 o r 2 0 79 through the use of this relationship we investigated the timing and magnitude of elevation change in the southern alps of new zealand and the sierra nevada of california the 18 o values of kaolinites from new zealand show an 6 decrease in the early pliocene that corresponds to an 2 km elevation change in the southern alps the 18 o of smectites from the sierra nevada show little change since 16 ma suggesting that these mountains have been a long standing topographic feature

seasonal variations in the upper arctic ocean as observed at t 3 hydrographic data from t 3 are analyzed to illustrate the behavior of the arctic mixed layer the mixed layer depth fluctuates 11 m annually and mixed layer salinity fluctuates 0 32 the fluctuations in total salt content are consistent with theoretical work by maykut and are in phase with mixed layer depth indicating changes in the mixed layer are controlled by salt flux deepening of the mixed layer brings 0 3 kcal cm 2 yr 1 of heat to the surface from the ocean below

dinosaur egg deposits in the cretaceous gyeongsang supergroup korea diversity and paleobiological implications abstract the taphonomy and depositional environments of dinosaur egg bearing deposits in the cretaceous gyeongsang basin korea are described and their paleobiological implications are discussed in the context of global geographic occurrences geological ages paleoenvironments and lithology the general depositional environment of dinosaur egg deposits in the gyeongsang supergroup is interpreted as dry floodplains with a semi arid climate and intermittent volcanic activity the diverse floodplain paleoenvironments include fluvial plains with meandering rivers to alluvial plains with episodic sheet flooding both global and korean dinosaur egg bearing deposits are generally restricted to the late cretaceous a phenomenon for which two possible explanations are proposed the first possible explanation for the temporal limitation of dinosaur egg preservation involves the appearance of angiosperms in the late jurassic the late cretaceous ecological dispersion of angiosperm trees into swamps and floodplains and the attendant change in herbivorous dinosaurs diets the second possible reason is related to nesting behavior in the cretaceous by contrast to the temporally limited occurrence of dinosaur eggs paleoenvironments of nesting areas are diverse ranging from inland areas to coastal areas these hypotheses may provide new directions for the study and understanding of dinosaur egg distribution in the context of geologic time

dinosaur eggshell isotope geochemistry as tools of palaeoenvironmental reconstruction for the upper cretaceous from the tremp formation southern pyrenees abstract the isotopic compositions 13 c and 18 o of dinosaur eggshells have been widely used in palaeoenvironmental studies although the geochemical signatures of eggshells are not usually contrasted with other proxies in this work the isotopic signatures of eggshells from a large maastrichtian succession from the tremp formation southern pyrenees spain are compared to those of carbonate pedogenic nodules occurring in the same levels the isotopic signatures of eggshells vary according to the stratigraphic unit and geographical location a group of samples from several localities corresponding to eggshells without significant diagenetic imprints has isotopic values differing from the associated nodules the late cretaceous isotopic composition record from the tremp fm is consistent that is the eggshells have distinct primary signatures preserved however the eggshells from another locality which exhibit neomorphed textures display isotopic signatures similar to the associated pedogenic carbonate which suggests a diagenetic isotopic signature and confirms alteration in the eggshells both microscopic and geochemical data suggest that an early meteoric diagenesis pedogenesis is responsible for the secondary signatures the 13 c values in the carbonate pedogenic nodules indicate a carbon isotopic composition typical of c3 plants although the slight difference in 13 c between the palaeosol carbonate of coeval successions may be due to slightly different palaeoenvironmental conditions the small discrepancy in the 13 c calculated for c3 plants from carbonate nodules and from eggshells may be because the palaeosol carbonate gives the isotopic composition of the vegetation grown at a local site whereas the 13 c from eggshells is a proxy for the ingested food in the area in which the dinosaurs lived the oxygen isotopic compositions from palaeosol carbonate nodules have been used for calculation of the air temperature and we may conclude that the mean air temperature in the studied area during the late cretaceous was approximately 21 c the use of this temperature gives rational results in the calculation of the oxygen isotopic composition of palaeosol carbonate by means of the isotopic composition of the eggshell carbonate additionally a relatively continuous isotopic record of nodules shows an overall vertical trend towards negative 13 c values and a high relative and steady 18 o content throughout the maastrichtian the k pg boundary was recorded by a negative excursion in 13 c in the carbonate nodules

influence of vertisol development on sauropod egg taphonomy and distribution at the auca mahuevo locality patagonia argentina abstract at the auca mahuevo locality in the upper cretaceous anacleto formation in patagonia argentina pedogenic processes associated with vertisol development affected changes in both individual titanosaur egg morphology and three dimensional egg distribution these changes resulted primarily from vertical and lateral movement within fluvial overbank sediments due to clay mineral expansion and contraction in alternating wet and dry seasonal conditions at the scale of individual sauropod eggs pedogenic sediment movement produced egg shearing eggshell fracture and displacement mechanical abrasion of egg ornamentation and alteration of egg size and shape movement of either individual eggs or subsets of eggs along slickensided surfaces 1 modified the number and relative position of eggs within individual clutches 2 combined eggs of one of more clutches produced by different females and 3 combined eggs from one or more nesting horizons producing a time averaged fossil assemblage these mechanisms of egg rearrangement suggest that accurate interpretation of dinosaur reproductive behavior using fossil egg assemblages preserved in fine grained fluvial overbank deposits require careful assessment of pedogenic processes

formation and evolution of the surface mixed layer and halocline of the arctic ocean fresh water from summer ice melt and the total freshwater content of the arctic ocean water column above the thermocline are estimated from vertical profiles of temperature and salinity observed on the i b oden 1991 cruise the seasonal ice melt ranges from 0 5 m to slightly above 1 m and is moderately uniform over the observation area regions of lower melting are seen over the morris jesup plateau the freshwater content is calculated relative to the salinity just above the thermocline north of the barents sea the freshwater content increases toward the interior of the arctic ocean showing that fresh water is advected from other regions into the observation area regions of different freshwater content are separated by fronts over the nansen gakkel ridge over the lomonosov ridge and in the western eurasian basin between waters derived from the eurasian and canadian basins denser water homogenized north of the barents sea is recognized by a temperature minimum layer the absence of the temperature minimum near the nansen gakkel ridge indicates that heat is transferred from the atlantic layer over a longer time than the shortest route would allow this observation can be explained if the layer circulates together with the atlantic layer i e toward the east and returns above the nansen gakkel ridge and along the amundsen basin north of the laptev sea this water formed north of the barents sea becomes covered by low salinity shelf water the increased freshwater content limits the winter convection so it no longer reaches the thermocline and an intermediate halocline is formed the halocline in the eurasian basin consists of water originating from winter convection in the arctic ocean north of the barents sea which then circulates around the basin such a formation mechanism also explains the observed distribution of low no water the strong density increase limits vertical exchange and the vertical diffusion coefficient in the halocline is small 1 10 6 m2 s 1 the increased temperature of the halocline shows that the heat lost upward by the atlantic layer mainly by double diffusive convection is trapped below the mixed layer

assimilating satellite concentration data into an arctic sea ice mass balance model 1979 1985 using satellite ice concentration data observed buoy velocities and a thermodynamic ice growth model we compute the time histories of the thickness distributions of four ice types level and ridged first year ice and level and ridged multiyear ice these histories are computed for seven regions covering the arctic ocean with a 10 day time step for 1979 through 1985 a blend of observed buoy motions and wind driven free drift velocities drives the advective and ridging parts of the model while climatological growth and melt rates determine the ice thickness the model adjusts the thickness distributions so that the modeled concentrations of open water first year ice and multiyear ice match the concentrations derived by kalman filtering of satellite passive microwave observations the major adjustment is to reduce modeled ice concentrations in summer and particularly in the peripheral seas to account for unmodeled melt the model includes an ice salinity parameterization which along with changes in ice volume gives the salt or freshwater flux from the ice our results show that the arctic ice cover consists primarily of multiyear ice 60 by area and 82 by volume and that most of this ice is ridged the average ice thickness is 2 7 m with a seasonal variation of 30 and an interannual variation of 10 the study also shows that for each cell and the arctic as a whole the changes in ice volume caused by growth minus melt approximately balance the changes caused by import minus export the annual ice export through fram strait varies from 1100 to 3000 km3 primarily because of variations in ice velocity all regions except the chukchi sea have a net ice growth a net export and a net salt input to the ocean surface the annual mean salt flux to the ocean surface from net ice production is 7 3 kg m 2 downward fluxes along the transpolar drift stream are larger than elsewhere the largest downward flux of 33 kg m 2 yr 1 in the nansen basin can be attributed to the strong divergence near fram strait a companion paper steele et al this issue uses these fluxes and ice velocities to derive the arctic ocean freshwater balance

tourmaline bearing rocks in the singhbhum shear zone eastern india evidence of boron infiltration during regional metamorphism frozen in reaction textures combined with mineral chemistry of tourmaline bearing metamorphic assemblages provide valuable information about fluid rock interaction during orogenesis tourmaline occurs in four distinct mineralogical associations in the singhbhum shear zone ssz of the precambrian east indian craton the tourmaline bearing rocks are associated intimately with pelitic to psammopelitic and quartzofeldspasthic rocks including meta granite the rocks were affected by two sets of folding f1 and f2 and ductile shearing associated with f1 during ca 1 6 1 8 ga tectonic activity in this belt quantitative geothermobarometry and the stability relations of the metamorphic assemblages developed in the pelitic rocks establish the presence of two episodes of metamorphism a prograde m1 event that culminated at 480 40 c 6 4 0 4 kbar and an m2 event that caused retrogression of the m1 assemblages field and petrographic observations in combination with data on chemical composition of tourmaline indicate three stages of tourmaline growth the earliest stage is represented by pretectonic pre metamorphic greenish yellow tourmaline cores in the tourmalinite from the surda area association a the textural relations demonstrate that in the second stage greenish yellow cores of oscillatory zoned tourmaline in the metagranite albite quartz biotite chlorite muscovite apatite magnetite association c very fine tourmaline grains in muscovite schist muscovite quartz association b and greenish yellow cores of tourmaline in biotite muscovite schist biotite muscovite magnetite chlorite apatite quartz association d crystallized during the f1 m1 events post tectonic greenish blue tourmaline belonging to the third stage replaces the earlier tourmaline grains along their margins and cracks compositionally tourmalines of all four associations fall in the alkali group most of the data fall in the dravite field with a few analyses straddling the boundary between schorl and dravite an abrupt compositional change was noted across the different color zones in the tourmaline grains this change is explained by one or more of the coupled substitutions al nar 1 car naal 1 and mg fe 1 where r mg fe2 mn integrating the field petrographic and phase compositional data it has been demonstrated that tourmaline growth in the second and third stages was induced by infiltration driven b metasomatism during prograde metamorphism of the rocks deep seated magma was the source of the b bearing hydrothermal fluid

stable isotopes sr ca and mg ca in biogenic carbonates from petaluma marsh northern california usa stable isotope sup 18 o sup 16 o and sup 13 c sup 12 c and minor element compositions sr ca and mg ca ratios of ostracodes and gastropods separated from marsh sediments from san francisco bay northern california were used to reconstruct paleoenvironmental changes in petaluma march over the past 700 yr the value of delta sup 18 o in the marsh carbonates reflects changes in freshwater inflow evaporation and temperature mg ca and sr ca in ostracode calcite reflect changes in both freshwater inflow and temperature although primarily reflect temperature changes in the salinity range of about 10 35 per thousand ostracode delta sup 18 o values show a gradual increase by 5 per thousand between 500 yr bp and the present probably reflecting rising sea level and increased evaporation in the marsh superimposed on this trend are higher frequency mg ca and delta sup 18 o variations 3 4 per thousand probably reflecting changes in freshwater inflow and evaporation a period of low mg ca occurred between about 100 300 cal yr bp suggesting wetter and cooler conditions during the little ice age higher mg ca ratios occurred 600 700 cal yr bp indicating drier and warmer conditions during the end of the medieval warm period both ostracode and gastropod delta sup 13 c values decrease up core reflecting decomposition of marsh vegetation which changes from c sub 4 delta sup 13 cmore approximately minus 12 per thousand to cam delta sup 13 c minus 26 per thousand type vegetation over time less

fram strait sea ice outflow 1 we summarize 24 years 1978 2002 of ice export estimates and examine over a 9 year record the associated variability in the time varying upward looking sonar uls thickness distributions of the fram strait a more thorough assessment of the pmw passive microwave ice motion with 5 years of synthetic aperture radar sar observations shows the uncertainties to be consistent with that found by kwok and rothrock 1999 giving greater confidence to the record of ice flux calculations interesting details of the cross strait motion profiles and ice cover characteristics revealed by high resolution sar imagery are discussed the average annual ice area flux over the period is 866 000 km2 yr between the 1980s and 1990s the decadal difference in the net exported ice area is 400 000 km2 approximately half the annual average except for the years with extreme negative nao correlation of winter ice area export with the nao index remains high r2 0 62 with thickness estimates from uls moorings we estimate the average annual ice volume flux 8 years to be 2218 km3 yr 0 07 sv over the 9 year uls ice thickness data set there is an overall decrease of 0 45 m in the mean ice thickness over the entire time series and a decrease of 0 23 m over the winter months december through march correspondingly the mode of the my ice thickness exhibits an overall decrease of 0 55 m and a winter decrease of 0 42 m these are significant trends whether these trends are indicative of the thickness trends of the arctic ocean is examined as the time varying behavior of the monthly uls thickness distributions can be related not only to the seasonal cycle in the basal growth and melt but also to the magnitude and pattern of ice motion in the arctic ocean and the proximity of the uls moorings to the ice edge

palaeoenvironments of the dinosaur bearing lameta beds maastrichtian narmada valley central india abstract the maastrichtian lameta beds of central india are intimately associated with the deccan lavas and are critical to determining upper cretaceous palaeoenvironments and palaeogeography of the area in the type jabalpur sub region four mappable units of the lameta beds are recognised the basal green sandstone is interpreted as a braided stream deposit the lower limestone characterised by brecciation and shrinkage cracks is interpreted as a sub aerially exposed palustrine flat with calcrete formation occurring on topographic highs of low relief plains the overlying mottled nodular beds exhibit a variable range of calcrete fabrics and morphologies including circum granular and linear cracks root casts and nodules these are interpreted as pedogenically modified sheet wash deposits of a semiarid alluvial plain the upper sandstone is a sheet flood deposit again pedogenically modified before arrival of the basal lava flows overall the lameta beds are considered to represent a regionally extensive maastrichtian regolith carbon and oxygen isotope analyses of calcareous components are entirely consistent with soil zone environments the 13c values are low typically 8 to 9 pdb demonstrating a strong input of carbon from the decay of terrestrial land plants calcrete 18o values are variable 5 to 10 pdb consistent with precipitation from meteoric water some of which was evaporatively modified in pools on the alluvial palustrine flat the lameta beds are well known for sauropod nesting sites and sedimentological analyses of these sites suggest that the animals selected topographic highs usually in marly or sandy soft sediment multiple nests with similar egg types probably indicate colonial nesting isotopic analyses of eggshell carbonate agree with earlier work suggesting that the sauropods ate a c3 plant food