climate and environment of a pliocene warm world the pliocene epoch 5 33 2 58 million years ago ma was a generally warmer and wetter interval with atmospheric co2 concentrations at or slightly above modern levels this paper provides an overview of pliocene vegetation sea surface temperatures and climate modelling outcomes most prominent changes in pliocene biome distribution compared to today include a northwards shift of temperate and boreal vegetation zones in response to a warmer and wetter climate as well as an expansion of tropical savannas and forests at the expense of deserts faunal analysis techniques and modelling experiments using the hadley centre climate model identified significantly higher pliocene sea surface temperatures at mid and high latitudes of the northern hemisphere with cooling or unchanged sea surface temperatures at low latitudes global mean annual surface temperatures mat are estimated to have been 2 to 3 c higher during the piacenzian 3 6 2 58 ma than today with a reduced equator to pole gradient the marine realm during the pliocene was characterised by a reconfiguration of ocean gateways particularly the narrowing of the indonesian seaway and closure of the central american isthmus which produced essentially a modern pattern of ocean circulation in the southern ocean a warm early pliocene gave way to late piacenzian cooling proxy data indicate a reduced east to west sea surface temperature gradient in the tropical pacific during the pliocene warmth the pliocene is one of the most intensively studied geological intervals of the pre quaternary no other warm period in the geological past yields such a unique combination of near modern atmospheric co2 concentrations palaeogeography and palaeobiology however this paper also identifies data gaps and shortcomings in the reconstruction of pliocene environments using proxy data and climate models on which future research should focus

nature of laminations and mineralization in rhinoceros enamel using histology and x ray synchrotron microtomography potential implications for palaeoenvironmental isotopic studies abstract incremental features of rhinoceros molar enamel were studied quantitatively on histological slices the different kinds of incremental features of enamel were related to one another and counted to determine the rate and duration of crown formation and to clarify the status of the laminations the mineralization and the microstructure of the enamel were examined in a rhinoceros molar germ using x ray synchrotron microtomography respectively using absorption and phase contrast mode at different levels of resolution from 45 71 m for the largest scale up to 0 28 m for the finest one the different microtomographic data were combined to obtain a multiscale integrated overview of the microstructure and mineralization in order to understand better the relationship between these two aspects additional human and herbivorous mammal teeth were examined qualitatively using histological sectioning to obtain a better understanding of laminations in mammal tooth enamel laminations regularly spaced features parallel to the retzius lines represent regular isochrons of enamel deposition this study shows that laminations and cross striations are equivalent daily features in enamel of rhinoceros humans and probably of middle sized and large herbivorous mammals in general laminations are shown to be three dimensional alignments of cross striations in addition to the fact that cross striations are visible only in prismatic enamel observation of histological slices and high resolution phase contrast x ray synchrotron microtomography demonstrate three main parameters influencing the dominant aspect of daily features in rhinoceros and human enamel the angle between prisms and retzius lines the enamel deposition rate and the thickness of the histological slices given their daily nature laminations can be used to determine the crown formation time of middle sized and big herbivorous mammals quantitative study of the enamel mineralization in the rhinoceros germ fragment using x ray synchrotron microtomography suggests that the innermost 20 m of the enamel near the enamel dentin junction are highly mineralised 77 90 of the final enamel mineralization during or just after the deposition of the corresponding enamel matrix integrated microtomographic study shows that this area corresponds to the thin aprismatic enamel layer at the edj level plus a thin layer of radial enamel directly adjacent it appears that in some parts of the enamel there may be a considerable time lag between matrix deposition and full maturation which could have important implications for geochemical studies this study reinforces the previously suggested hypothesis that isotopic measurements derived from the innermost enamel may represent the period most closely related to matrix secretion by using information derived from incremental features laminations and retzius lines and restricting the isotopic measurements to the innermost part of the enamel precise temporal calibration of isotopic signals should be possible and the complication of time averaging due to enamel maturation could be avoided or strongly reduced

latitudinal temperature gradient during the cretaceous upper campanian middle maastrichtian y18o record of continental vertebrates latitudinal variations in model biogenic apatite d18o values were calculated using fractionation equations of vertebrates and weighted rainfall y18o values along with mean annual air temperatures provided by iaea wmo meteorological stations the reference equation obtained was used to compute a continental temperature gradient for the late campanian middle maastrichtian interval by using published and new d18o values of phosphate from vertebrates samples are mainly tooth enamel from crocodilians and dinosaurs that lived at paleolatitudes ranging from 83 4 n alaska to 32 3 s madagascar the temperature gradient was less steep 0 4 0 1 c latitude than the present day one 0 6 c latitude with temperatures that decreased from about 30 c near the equator to about 5 c at the poles above 30 of paleolatitude air temperatures were higher than at present the validity of these results is discussed by comparison with climatic criteria inferred from paleontological paleobotanical and sedimentological data the latitudinal distribution of oxygen isotope compositions of continental vertebrates is potentially a powerful tool for quantifying mesozoic terrestrial climates

water volume variations in lake izabal guatemala from in situ measurements and envisat radar altimeter ra 2 and advanced synthetic aperture radar asar data products summary the water storage variations in lakes affect their physical chemical and biological processes besides the water masses of these waterbodies reflect the balance of the rainfall and evaporation with surface and ground waters the lake s water volume is estimated combining water level variations with accurate bathymetry and shore topography maps lake izabal is the largest waterbody of guatemala approximately 673 29 km 2 its water volume has been estimated in the past but the volume variations are still unknown the lake water level variations are monitored in situ since 2004 but regrettably accurate information about the bathymetry and shore topography is not available the main objective of this study was to make a first estimate of the lake izabal water volume variations to do this we combined level variations and inundated area variations the lack of accurate bathymetry and topography maps was overcame by using inundated area variations in the assumption that every level change reflects an inundated area response depending on bathymetry and shore topography the level variations were estimated from an in situ moored gauged in the lake and from the envisat radar altimeter ra 2 the inundated area variations were obtained using 12 envisat advanced synthetic aperture radar asar images prior to the area estimates the lake s shoreline was extracted making use of a chain of existing image processing algorithms the correlation analysis between in situ lake levels and inundated area variations yielded a correlation coefficient of 0 9 the volume variations of the lake were then estimated on the dates of the acquired sar images then a group of rating curves relating level area and volume were developed in order to extend the area and volume estimates to the whole study time period february 2003 to december 2006 the lake levels from the ra 2 dataset were entered to the rating curves the estimated water volume variations of lake izabal range between 8271 2 10 6 m 3 17th december of 2005 and 9018 15 10 6 m 3 15th july of 2006 in agreement with the most recent estimation of the lake izabal water volume 8300 10 6 m 3 regarding the inundated area variations they range between 672 44 10 6 m 2 17th december of 2005 and 677 2 10 6 m 2 15th july of 2006 in agreement with the guatemalan government information 673 29 km 2 the water volume inundated area and water level fluctuations of the lake izabal show a strong seasonal signal with high stages during the rainy season may november and low stages during the dry seasons december april these results give valuable information for the lake izabal management and strengthen the idea of using remote sensing as a powerful and cheap complementary tool for hydrologic purposes

a global synthesis of the marine and terrestrial evidence for glaciation during the pliocene epoch abstract the pliocene climate is globally warm and characterised by high atmospheric carbon dioxide concentrations yet the terrestrial and marine scientific communities have gathered considerable evidence for substantial glaciation events in both the northern and southern hemisphere prior to the quaternary evidence on land is fragmentary but marine records of glaciation present a more complete history of pliocene glaciation here we present a global compilation of the terrestrial and marine glacial evidence for the pliocene and demonstrate four glaciation events that can be identified in the southern and or northern hemisphere prior to the latest pliocene intensification of northern hemisphere glaciation there are two globally recognisable glacial events in the early pliocene c 4 9 4 8 ma and c 4 0 ma one event around the early late pliocene transition c 3 6 ma and one event during marine isotope stage m2 c 3 3 ma long term climate cooling decreasing carbon dioxide concentrations in the atmosphere and high climate sensitivity in the pliocene probably facilitated each glaciation event however the mechanisms behind the early pliocene glacial events are unclear the global glaciation at c 3 3 ma may be caused by changes in ocean gateways whereas the decline in carbon dioxide concentrations is important for the latest pliocene intensification of northern hemisphere glaciation

climate and biomes in the west mediterranean area during the pliocene a new pollen derived method of climatic quantification based on the mutual climatic range of plant taxa has been applied to 17 pliocene pollen sequences in the west mediterranean area the latitudinal gradient observed in the pollen data was confirmed by the climatic reconstructions there is a gradient from north to south both for temperatures and precipitation at the beginning of the pliocene 5 32 5 ma the climate in the north mediterranean area was on average warmer and more humid than today respectively 1 4oc and 400 700 mm in the south mediterranean region the climate was both warmer and drier than today respectively equal to or 5oc higher and drier or equal humidity the pollen based climate estimates were then used to reconstruct biomes for the region the results show the occurrence of three biomes the broad leaved evergreen warm mixed forest the xerophytic woods scrub biome and the warm grass shrub biome these biomes are still represented today in the mediterranean region despite different thermic and water conditions

quantification and propagation of errors when converting vertebrate biomineral oxygen isotope data to temperature for palaeoclimate reconstruction oxygen isotope analysis of bioapatite in vertebrate remains bones and teeth is commonly used to address questions on palaeoclimate from the eocene to the recent past researchers currently use a range of methods to calibrate their data enabling the isotopic composition of precipitation and the air temperature to be estimated in some situations the regression method used can significantly affect the resulting palaeoclimatic interpretations furthermore to understand the uncertainties in the results it is necessary to quantify the errors involved in calibration in some situations the regression method used can significantly affect the resulting palaeoclimatic interpretations while quantification of the errors involved in calibration is necessary to understand the uncertainties in the results studies in which isotopic data are converted rarely address these points and a better understanding of the calibration process is needed this paper compares regression methods employed in recent publications to calibrate isotopic data for palaeoclimatic interpretation and determines that least squares regression inverted to is the most appropriate method to use for calibrating causal isotopic relationships we also identify the main sources of error introduced at each conversion stage and investigate ways to minimise this error we demonstrate that larger sample sizes substantially reduce the uncertainties inherent within the calibration process typical uncertainty in temperature inferred from a single sample is at least 4oc which multiple samples can reduce to 1 2oc moreover the gain even from one to four samples is greater than the gain from any further increases we also show that when converting 18oprecipitation to temperature use of annually averaged data can give significantly less uncertainty in inferred temperatures than use of monthly rainfall data equations and an online spreadsheet for the quantification of errors are provided for general use and could be extended to contexts beyond the specific application of this paper palaeotemperature estimation from isotopic data can be highly informative for our understanding of past climates and their impact on humans and animals however for such estimates to be useful there must be confidence in their accuracy and this includes an assessment of calibration error we give a series of recommendations for assessing uncertainty when making calibrations of 18obioapatite 18oprecipitation temperature use of these guidelines will provide a more solid foundation for palaeoclimate inferences made from vertebrate isotopic data

pliocene early pleistocene climatic trends in the italian peninsula based on stable oxygen and carbon isotope compositions of rhinoceros and gomphothere tooth enamel abstract the pliocene and early pleistocene 5 2 1 ma palaeoclimate for localities in italy is evaluated using stable carbon and oxygen isotope compositions of tooth enamel of fossil specimens from rhinocerotidae stephanorhinus sp and gomphotheriidae anancus sp taxa carbon isotope composition was measured in the structural carbonate 13 c while oxygen isotope values were determined both in the structural carbonate 18 o co3 and the phosphate 18 o po4 of bioapatite the 13 c co3 values indicate that the taxa were grazers browsers of a pure c 3 vegetation low 13 c co3 values for central and north italy indicate a humid climate with woodlands and forest cover in the pliocene for northern localities the 13 c values increase between mn16a and mnq16b biozones most likely linked to the northern hemisphere glaciation at 2 7 ma after the mid pliocene warm period for central italy the values have a wide range with a long term increasing trend in the early pleistocene indicating more arid climate and or more open vegetation overall the 18 o po4 values in central italy change together with the 13 c co3 values and are taken to reflect the warmer wetter interglacials and cooler more arid glacial phases the 18 o po4 values in north italy are lower than those in central italy and show no clear temporal trend one explanation for the low values especially in mn14 15 biozone is that these 18 o po4 values do not reflect entirely the isotopic composition of local precipitation but river waters from the alps with 18 o depleted isotopic compositions or a n s directed rain shadow effect on the precipitation in general the new isotope data agree well with palaeoclimate reconstructions based on palynological and other proxies

pliocene and early pleistocene paleoenvironmental conditions in the pannonian basin hungary slovakia stable isotope analyses of fossil proboscidean and perissodactyl teeth abstract stable carbon and oxygen isotope values of structural carbonate 13c 18oco3 and phosphate 18opo4 in bio apatite were measured for fossil mammalian teeth from slovakia and hungary oxygen isotope compositions of enamel provide new quantitative records of the pliocene and early pleistocene paleoclimate in the pannonian basin pb the 18opo4 values were used to study the temporal variations in the oxygen isotope compositions of precipitation and the changes in temperature over the pb the new o isotope data suggest that surface air temperatures between 4 5 and 2 0 ma were 1 to 4 c warmer with about 700 mm yr more precipitation compared to the present c isotope analyses of samples from proboscideans anancus sp mammut sp and perissodactyls stephanorhinus sp tapirus sp from the pliocene mn15 mn16 and early pleistocene mn17 suggest that they were primarily c3 browsers the mean 13c value is high at 4 5 to 3 7 ma mn14 15 during the pliocene warm period and decreases at about 3 5 to 3 0 ma mn16 mid pliocene warm period with the onset of more humid conditions in europe the 13c values return to higher values from 2 5 ma onwards mn17 most likely reflecting more arid conditions as a consequence of the onset of the northern hemisphere glaciation

a 16 ma record of paleodiet using carbon and oxygen isotopes in fossil teeth from pakistan abstract the siwalik sequence of northern pakistan contains a 16 ma record of paleosol carbonate and fossil teeth from which a record of paleovegetation can potentially be reconstructed and compared the carbon isotopic composition of paleosol carbonate and organic matter from siwalik strata reflects a major paleoecological change on the floodplains of major rivers beginning7 3 ma ago by 6 ma c 3 dominated plant communities probably composed of mostly trees and shrubs were displaced by nearly continuous c 4 grassland we find that the carbon isotopic ratios in herbivore tooth enamel reflect this dramatic ecologic shift carbonate in enamel older than 7 ma averages 11 in 13 c pdb consistent with a largely c 3 diet enamel from the plio pieistocene averages 1 9 in 13 c similar to the value displayed by modern c 4 grazers analysis of post burial carbonate cements and the concordance with isotopic evidence from paleosols argues strongly against major isotopic alteration of the enamel while coexisting bone may have been altered early in burial this study confirms that enamel apatite is useful for paleodietary reconstruction much further back in the geologic record than was previously thought

implications for the late pleistocene climate in finland and adjacent areas from the isotopic composition of mammoth skeletal remains nine samples of subfossil bone and teeth remains from woolly mammoth mammuthus primigenius discovered in finland russian karelia and western russia were analyzed for the oxygen isotope composition of the phosphate fraction and the carbon and oxygen isotope composition of the carbonate fraction in skeletal apatite the samples have been radiocarbon dated in previous studies and are of late middle weichselian to late weichselian age the preservation of the samples was tested analyzing the chemical composition and checking the isotopic equilibrium between the phosphate and carbonate components in skeletal apatite according to these tests five out of the nine samples were determined to have retained their original isotopic composition these samples were used to estimate late pleistocene climatic conditions in finland and neighboring areas based on the best preserved enamel samples the isotopic composition of oxygen in late pleistocene precipitation was 1 3x lower than that in the mean annual precipitation in southern and central finland today using the relationship between the isotopic composition of precipitation and the ambient temperature it can be estimated that the mean temperatures during the middle weichselian ice free period were 2 6 8c lower compared to the present day values d 2005 elsevier b v all rights reserved

reassessment of recommendations for processing mammal phosphate δ18o data for paleotemperature reconstruction abstract the stable oxygen isotope composition of phosphates 18 o p extracted from vertebrate bone and teeth material is widely used for paleotemperature reconstruction over the quaternary period however inconsistency in analytical and statistical procedures used by different researchers for recalculation of mean air temperatures from measured 18 o p values makes integration of different data sets challenging therefore consistency in both stable isotope data processing and the application of appropriate statistical procedures is highly desirable this paper evaluates the uncertainty associated with two most commonly used regression methods least squares inverted fit and transposed fit we assessed the performance of both fits by designing real life experiments using various data sets we used both regression models to reversely calculate the differences between actual recorded in real life values and values calculated from the regression models our calculations clearly show that the mean absolute errors are always substantially higher for the inverted fit and the transposed fit always returned mean values closer to the values measured in real life in all studied scenarios the predictive models performed better than causal models returning mean absolute errors by 12 65 lower in the paper we also examined the other main sources of uncertainty concerns about calculation of 18 o p of phosphates from 18 o c of carbonates averaging of 18 o w in precipitation and highlight major challenges in the field of phosphate stable oxygen isotope biogeochemistry the estimation of paleotemperatures from isotope records could be improved by employing globally consistent calculation procedures

the retention of primary oxygen isotope compositions of fossil elephant skeletal phosphate fossil elephant remains from sediments of plio pleistocene age in the vicinity of lake turkana kenya provide insights into the ability of the phosphate oxygen system to preserve original 18o values 18op in the depositional environment individual fossil specimens exhibit systematic variations in the 18op values of their various tooth and bone components differences in 18op values between these skeletal components can be as high as 3 6 despite the fact that equivalent phases for individual modern elephants have 18op values which vary by less than 0 6 xrd traces of the different skeletal phases of modern and fossil samples also infer differential preservation of primary apatite crystallinities among the various fossil phases fossil samples of dentine cementum and bone have x ray spectra with sharper and more intense peaks compared to their modern counterparts but little change in crystallinity is observed for fossil enamel samples a model based on the premise that the enamel phase preserves primary isotope signatures and that the accompanying skeletal phases are partially re equilibrated with the fluids associated with the microbial decomposition of the elephant s carcass is consistent with the features of the 18op dataset this isotopic evidence in conjunction with the physical and chemical attributes of enamel has led us to postulate that enamel could be preserving primary isotope signatures while other skeletal components are affected to varying degrees by alteration processes in the burial environment

antarctic role in northern hemisphere glaciation earth s climate underwent a major transition from the warmth of the late pliocene when global surface temperatures were 2 to 3 c higher than today to extensive northern hemisphere glaciation nhg 2 73 million years ago ma we show that north pacific deep waters were substantially colder 4 c and probably fresher than the north atlantic deep water before the intensification of nhg at 2 73 ma the atlantic pacific temperature gradient was reduced to

middle pliocene sea surface temperatures a global reconstruction identification and analyses of pliocene marine microfossils from 64 globally distributed stratigraphic sequences have been used to produce a middle pliocene sea surface temperature reconstruction of the earth this reconstruction shows little or no change from current conditions in low latitude regions and significant warming of the ocean surface at mid and higher latitudes of both hemispheres this pattern of warming is consistent with terrestrial records and suggests a combination of enhanced meridional ocean heat transport and enhanced greenhouse effect were responsible for the middle pliocene warmth

oxygen isotope variations in phosphate of biogenic apatites iv mammal teeth and bones groups of rats grown from birth to death in identical conditions but with different 18o of drinking water w were studied for variations of 18o of their body water bw and bone phosphate p there is a high linear correlation r 0 99 between bw and between p and w the regression lines have similar slope coefficients 0 53 and 0 49 values of p of different teeth and bones are the same within the precision of the method 0 5 the isotopic fractionation coefficient between phosphate and body water is 1 0178 and close to the estimated value of 1 0173 derived from the phosphate paleotemperature equation deviations from constant fractionation between bone phosphate and environmental drinking water depend primarily on rates of drinking and metabolism environment conditions have relatively little effect on oxygen isotope fractionation between water sources and bone phosphate

a calibrated mammal scale for the neogene of western europe state of the art abstract a magnetobiostratigraphically calibrated mammal scale for the neogene of western europe is presented in this paper the mammal neogene mn units originally proposed by mein report on activity rcmns working groups 1975 have been re defined here on the basis of first appearances of selected small and large mammal taxa the chronology of the lower boundaries of each unit had been established mostly after the significant magnetobiostratigraphic framework developed in the last decade in a number of spanish basins ebro calatayud daroca valles penedes teruel fortuna cabriel and guadix baza in the case of the early and middle miocene particularly mn 1 mn 2 and mn 3 the authors have also taken into account the magnetobiostratigraphic framework developed in the north alpine foreland basin some alternative correlations of the magnetostratigraphic data from this last basin are proposed in order to achieve a higher degree of consistence with the data from the iberian basins a quite well established magnetostratigraphic calibration of the mn boundaries can be proposed for most of the neogene from middle miocene to late pliocene on the other hand the chronological boundaries of the early miocene mn units are still poorly constrained due to 1 scarcity of well studied continuous thick magnetostratigraphic sections 2 the difficulty in defining the boundaries of the mn zones for this time span due to the relative homogeneity and persistence of the fossil rodent faunas and the absence of significant large mammal dispersal events some of the troubles which arise with the application of the mn units strengthen the need to take into account the palaeobiogeographical meaning of these units and their real suitability to date and correlate through extensive geographic areas

eocene oligocene latitudinal climate gradients in north america inferred from stable isotope ratios in perissodactyl tooth enamel abstract the eocene oligocene transition 34 ma was one of the most pronounced episodes of climate change of the cenozoic in order to investigate this episode of global climate cooling in north america we analyzed the carbon and oxygen stable isotope composition of the carbonate component of 19 perissodactyl horse and rhino tooth enamel samples from the eocene oligocene rocks of the cypress hills formation southwestern saskatchewan canada we then compared the results with previously published data from the us great plains nebraska south dakota and wyoming average 1 perissodactyl enamel 13 c values vs v pdb in the eocene 8 8 0 3 and oligocene 9 0 0 3 are indistinguishable suggesting no major change in mean annual precipitation in saskatchewan across the transition the 13 c values in saskatchewan indicate the presence of arid ecosystems and are slightly higher than those in the us great plains suggesting drier conditions at higher latitudes with respect to oxygen isotopes average 1 perissodactyl enamel 18 o values vs v smow in the eocene 19 8 2 0 and oligocene 20 1 3 6 are also indistinguishable suggesting no change in the 18 o of meteoric precipitation across the transition in saskatchewan enamel 18 o variability is much larger in the oligocene vs eocene indicating a large increase in temperature seasonality this increase in enamel 18 o variability is much larger than that recorded in the us great plains suggesting that higher latitudes are more sensitive to major episodes of climate change with respect to temperature seasonality finally our data indicate no major change in the oligocene vs eocene latitudinal gradient in local water 18 o in north america which suggests no change in mean annual temperature gradients across the transition this result supports the hypothesis that ascribes the climate change of the transition to a drop in atmospheric p co 2 because climate models show that this mechanism produces uniform cooling at mid latitudes

oxygen isotope analyses of co existing carbonate and phosphate in biogenic apatite a way to monitor diagenetic alteration of bone phosphate abstract the oxygen isotopic composition of phosphate 18 op and structural carbonate 18 oc of hydroxylapatite was determined in 31 bone and tooth samples of modern mammals from different countries these two variables are highly correlate r 2 0 98 and the calculated best fit of linear regression is very similar to the equation calculated from the phosphate and carbonate palaeotemperature equations 1 2 according to previous measurements 3 6 on fossils of different ages from different areas it seems quite improbable to find isotopically altered skeletal remains showing a good correlation between 18 op and 18 oc as is the case with modern samples it therefore seems possible at least in some cases to use these measurements for monitoring fossil bone and tooth diagenetic alteration when a set of points lie on the equilibrium line or close to it the 18 o values could be considered close to the original values in contrast when the points lie to the left or to the right of this line this probably means that the values are diagenetically modified due to interaction with meteoric water or 18 o enriched water respectively

carbon isotope ratio of cenozoic co2 a comparative evaluation of available geochemical proxies 1 the carbon isotope ratio 13c of plant material is commonly used to reconstruct the relative distribution of c3 and c4 plants in ancient ecosystems however such estimates depend on the 13c of atmospheric co2 13cco2 at the time which likely varied throughout earth history for this study we use benthic and planktonic 13c and 18o records to reconstruct a long term record of cenozoic 13cco2 confidence intervals for 13cco2 values are assigned after careful consideration of equilibrium and non equilibrium isotope effects and processes as well as resolution of the data we find that benthic foraminifera better constrain 13cco2 compared to planktonic foraminiferal records which are influenced by photosymbiotes depth of production seasonal variability and preservation furthermore sensitivity analyses designed to quantify the effects of temperature uncertainty and diagenesis on benthic foraminifera 13c and 18o values indicate that these factors act to offset one another our reconstruction suggests that cenozoic 13cco2 averaged 6 1 0 6 1 while only 11 2 million of the last 65 5 million years correspond to the pre industrial value of 6 5 with 90 confidence here 13cco2 also displays significant variations throughout the record at times departing from the pre industrial value by more than 2 thus the observed variability in 13cco2 should be considered in isotopic reconstructions of ancient terrestrial plant ecosystems especially during the late and middle miocene times of presumed c4 grassland expansion

the major composition of a middle late eocene salt lake in the yunying depression of jianghan basin of middle china based on analyses of fluid inclusions in halite abstract during the cretaceous tertiary transition in eastern china abundant halites formed in non marine areas many continental salt deposits from inland salt lakes were formed in eastern china in faulted basins as a result of the northward movement and collision of the indo china plate with the eurasian plate including the bohai gulf basin however a marine transgression versus a non marine origin of these evaporites remains to be determined primary fluid inclusions trapped in halite deposits can directly record the composition of evaporated seawater or salt lake water such as those in the cretaceous halite in the khorat plateau laos and thailand area can resolve the origins of the evaporate deposits recent fluid inclusions data in the khorat plateau coincide with the predicted secular variation of seawater and are comparable to other fluid inclusions in cretaceous marine halite indicating these fluid inclusions are directly related to a marine transgression our analyses in this study shows that the average k mg2 and so 4 2 contents are 8 8 5 0 and 6 8 g l respectively in the primary fluid inclusions in halite of middle late eocene from the yunying depression of china these numbers are much less than those in the contemporary spanish primary fluid inclusions in halite precipitated from seawater 16 4 36 3 and 12 5 g l for k mg2 and so 4 2 respectively furthermore br contents of all fluid inclusion samples in halite from the yunying depression are lower than 2 ppm vs 55 58 ppm at the base of spanish contemporary marine halite and their 37cl values range from 0 11 to 2 94 vs 0 09 to 0 24 in sylvite of spanish deposit indicating that the compositions of the middle late eocene brines trapped in halite in the yunying depression of china are very different from those derived from the contemporary seawater and are considered to be resulted from evaporation of an inland saline lake water with little influence of seawater

isotopic reconstruction of past continental environments abstract vertebrate fossils and continental sediments provide a rich record of variations in the isotopic composition of surface environments to interpret these records a greater understanding of isotopic sources as well as fractionations associated with animal physiology soil geochemistry and diagenesis has been essential tooth enamel and fish otoliths yield subannual records of surface environments whereas soil minerals may integrate signals over many thousands of years carbon isotope variations in fossil vertebrates and soils record changes in the structure of vegetation and the isotope composition and concentration of atmospheric co2 oxygen isotope variations may be indirectly related to climate through reconstruction of the oxygen isotope composition of meteoric water or directly related to temperature through application of oxygen isotope paleothermometry to soil minerals or otoliths in africa nitrogen isotope variations show promise as a proxy for rainfall abundance though the gen

seasonality intensification and long term winter cooling as a part of the late pliocene climate development abstract a mutual climatic range method is applied to the mediterranean marine pollen record of semaforo vrica section calabria italy covering the period from 2 46 ma to 2 11 ma the method yields detailed information on summer annual and winter temperatures and on precipitation during the nine obliquity and precession controlled glacial periods marine isotope stages 96 to 80 and eight interglacial periods marine isotope stages 95 to 81 characterising this time interval the reconstruction reveals higher temperatures of at least 2 8 c in mean annual and 2 2 c in winter temperatures and 500 mm in precipitation during the interglacials as compared to the present day climate in the study area during the glacials temperatures are generally lower as compared to the present day climate in the region but precipitation is equivalent along the consecutive interglacials a trend toward a reduction in annual and winter temperatures by more than 2 3 c and toward a higher seasonality is observed along the consecutive glacials a trend toward a strong reduction in all temperature parameters of at least 1 6 c is reconstructed climatic amplitudes of interglacial glacial transitions increase from the older to the younger cycles for summer and annual temperatures the cross spectral analyses suggest obliquity related warm humid cold dry interglacial glacial cycles which are superimposed by precession related warm dry cold humid cycles a time displacement in the development of temperatures and precipitation is indicated for the obliquity band by temperatures generally leading precipitation change at 4 kyr and on the precession band of 9 6 kyr in maximum

stable isotope evidence of late mis 3 to middle holocene palaeoenvironments from sehonghong rockshelter eastern lesotho evidence for human occupation of southern africa s high altitude maloti drakensberg mountains is surprisingly common in the last glacial yet the attraction of this relatively severe cold region for hunter foragers remains unclear sehonghong rockshelter 1870 m asl in the eastern lesotho highlands provides evidence for human occupation spanning marine isotope stage 3 through the late holocene excellent organic preservation provides opportunities for establishing multiple palaeoenvironmental proxy records to address this conundrum in high altitude zones the proportions of c3 and c4 plants archived in soil organic matter and faunal enamel provide sensitive indicators of past temperature shifts we first extended the radiocarbon chronology to ca 35 ka using abox sc radiocarbon dates of charcoals next we analysed stable isotopes in soil organic matter from the sedimentary sequence and in faunal tooth enamel from the newly dated lower strata the results suggest predictably that c3 vegetation and low temperatures prevailed until early warming at ca 15 ka with a series of sharp shifts thereafter low values for 13c and 18o in faunal enamel ca 33 ka suggest a negative temperature excursion at this time and potentially greater precipitation as snowfall in the highlands compared with lower altitudes

orogeny forced terrestrial climate variation during the late eocene early oligocene in europe terrestrial climatic data reflect variable and often conflicting responses to the global cooling event at the eocene oligocene transition ca 34 ma stable isotopic compositions of the tooth enamel of large water dependent herbivorous terrestrial mammals are investigated here to better understand the european continental climate during the late eocene early oligocene high 18opo4 and 13c values reflect a semiarid climate and ecosystem in the late eocene in the west southwest region of europe these conditions prevailed until at least 33 ma after which it became more humid a similar change was recorded north of the alpine thrust but it occurred 2 m y earlier the north and west southwest regions show a significant offset in 18opo4 composition between 35 and 31 ma indicating the influence of different air trajectories with different moisture sources atlantic versus tethys this also marks the presence of an orographic height in central europe from the latest eocene after 31 ma a large drop in 18opo4 is registered explained by altitude induced fractionation on meteoric water isotopic composition the related paleoaltitude change is estimated to be 1200 m and the uplift could have taken place along the alpine dinaridic orogenic system

can carbon 13 in large herbivores reflect the canopy effect in temperate and boreal ecosystems evidence from modern and ancient ungulates abstract local environmental conditions under dense canopy are known to result in depletion in 13c abundance in plants compared to an open land context this canopy effect has been observed in tropical as well as in mid latitude forest ecosystems however the impact of the canopy effect on tissue 13c abundance of temperate and boreal forest dwelling herbivores has not been thoroughly explored nevertheless the canopy effect has been suggested to explain a decrease of about 3 in collagen 13c values in ancient large herbivores from western europe during the forest expansion of the late glacial early holocene period ca 15 000 6000 cal bp some papers have considered the 13c decrease in large herbivore as the main result of global change in atmospheric co2 content a detailed review of 13c values of large herbivores reindeer red deer roe deer and bison from open and closed environments from high and mid latitudes confirm that the canopy effect observed in plants is passed on to their consumers in the paris basin the decline in 13c values of large herbivores at the late glacial early holocene transition around 10 000 years bp appears to be different according to the considered species namely red deer roe deer and large bovines bison and aurochs moreover differences in the pattern of decrease in 13c values are observed in red deer between french northern alps and french jura these differences among species in their isotopic response through time for a given geographical location and within species from different locations suggest variance in ecological responses of species that are associated with the relative use of forested habitat as a result 13c abundances in collagen can be considered as a direct tracker of the degree of closure of the habitat of ancient herbivores

early eocene carbon isotope excursions and landscape destabilization at eccentricity minima green river formation of wyoming repeated global reorganizations of carbon cycling and biotic oceanic and terrestrial processes occurred during the early eocene and appear to have been paced by cyclic variations in the eccentricity of the earth s orbit the phase relationship s between insolation variation terrestrial paleoclimate and atmospheric pco2 during these events remains enigmatic however due to their poorly constrained timing relative to specific orbital configurations here we use tiered interpolation between radioisotopic ages and paleomagnetic polarity chrons to compare high resolution 13c and lithofacies records from the wilkins peak member of the green river formation of western north america to a fe intensity xrf record from the western atlantic ocean and to numerical solutions for earth s orbital configuration wilkins peak member lithofacies stacking patterns record cyclic geomorphic responses to insolation and climate fluctuations spanning an interval of 1 8 ma previous macrostratigraphic analyses using 40ar 39ar and u pb ash bed ages indicate that these cycles reflect long and short eccentricity modulation of precession hydrologic variance appears to have occurred inversely with intervals of maximum sediment advection with carbonate and evaporite dominated lacustrine modes during eccentricity maxima and siliciclastic dominated alluvial modes during eccentricity minima stable carbon isotope analyses of 126 meters of wilkins peak member strata reveal a regular 5 per mil oscillation between high 13c lacustrine modes and low 13c alluvial modes tiered interpolation between paleomagnetically characterized terrestrial ash beds facilitates the integration of 11 radioisotopic ages with the geomagnetic polarity timescale resulting in significant expansion of chron c23 and shortening of chron c22 relative to timescales based on seafloor magnetic anomaly profiles the new proposed timescale permits direct comparison of terrestrial and marine climate proxy records from the early eocene climatic optimum at ca 250 kyr 250 kyr resolution and reveals prominent 100 kyr and 405 kyr scale oscillations within both records wilkins peak member 13c minima which occurred during low eccentricity alluvial modes likely coincided with global 13c minima scenario 1 but may alternatively reflect productivity driven local effects within lake gosiute scenario 2 if scenario 1 proves accurate early eocene negative 13c hyperthermal excursions occurred during eccentricity minima rather than maxima as formerly believed

mammoth tooth enamel growth rates inferred from stable isotope analysis and histology abstract mammoth mammuthus sp teeth are relatively abundant in quaternary deposits from eurasia and north america and their isotopic compositions can be used to reconstruct past seasonal patterns in precipitation diet and migration strategies for collecting and interpreting such data however are strongly dependent on growth rates which can vary among species individuals and within teeth in this study we use histological and isotopic measurements to determine enamel growth rates for a columbian mammoth mammuthus columbi tooth in two directions using histology the growth rate through the enamel thickness et perpendicular to the height of the tooth is estimated at 0 8 to 1 5 mm yr isotopic sampling through the innermost 0 36 mm of the et recovered less than half a period of variation i e half an inferred year of growth which is consistent with the histological estimate for et growth rate a combination of histological and isotopic measurements suggests that the enamel extension rate growth in the height of the tooth is 13 14 mm yr knowledge of enamel growth rates should improve the design and interpretation of future isotopic studies of mammoth teeth the combination of histological and isotopic measurements may also prove useful in determining growth rates for other extinct taxa

palaeoenvironment and palaeoclimate of the middle miocene lake in the steinheim basin sw germany a reconstruction from c o and sr isotopes of fossil remains a differentiated reconstruction of palaeolimnologic environmental and climatic conditions is presented for the middle miocene long term freshwater lake 14 3 to 13 5 ma of the steinheim basin on the basis of a combined c o and sr isotope study of sympatric skeletal fossils of aquatic and terrestrial organisms from the lake sediments the oxygen isotope composition for lake water of the steinheim basin 18oh2o 2 0 0 4 vsmow n 6 was reconstructed from measurements of 18opo4 of aquatic turtle bones the drinking water calculated from the enamel of large mammals proboscideans rhinocerotids equids cervids suids has 18oh2o values 18oh2o 5 9 1 7 vsmow n 31 typical for middle miocene meteoric water of the area this 18oh2o value corresponds to a mean annual air temperature mat of 18 8 3 8 c calculated using a modern day 18oh2o mat relation hence large mammals did not use the lake water as principal drinking water in contrast small mammals especially the then abundant pika prolagus oeningensis drank from 18o enriched water sources 18oh2o 2 7 2 3 vsmow n 7 such as the lake water differences in sr and o isotopic compositions between large and small mammal teeth indicate different home ranges and drinking behaviour and support migration of some large mammals between the swabian alb plateau and the nearby molasse basin while small mammals ingested their food and water locally changes in the lake level water chemistry and temperature were inferred using isotopic compositions of ostracod and gastropod shells from a composite lake sediment profile calcitic ostracod valves ilyocypris binocularis 18o 1 7 1 2 vpdb 13c 0 5 0 9 vpdb n 68 and aragonitic gastropod shells gyraulus spp 18o 2 0 1 3 vpdb 13c 1 1 1 3 vpdb n 89 have 18o and 13c values similar to or even higher than those of marine carbonates 13c values of the biogenic carbonates parallel lake level fluctuations while 18o values scatter around 2 2 and reflect the short term variability of meteoric water inflow vs longer term evaporation 87sr 86sr ratios of aragonitic gyraulus spp gastropod shells parallel the lake level fluctuations reflecting variable inputs of groundwater and surface waters using a water 18oh2o value of 2 0 vsmow water temperatures calculated from skeletal tissue 18o values of ostracods are 16 7 5 0 c gastropods 20 6 5 6 c otoliths 21 8 1 4 c and fish teeth 17 0 2 7 c the calculated mat 19 c lake water temperatures 17 to 22 c and the 18o enriched water compositions are indicative of warm temperate climatic conditions possibly with a high humidity during this period vegetation in the area surrounding the basin was largely of the c3 type as indicated by carbon isotopic compositions of tooth enamel from large mammals 13c 11 1 1 1 vpdb n 40

exploring the variation of the δ18op and δ18oc relationship in enamel increments abstract comparisons between the oxygen isotope ratios in the carbonate and phosphate fractions of bioapatite have been proposed and applied as an internal check for diagenesis because oxygen in the two compartments is believed to be incorporated simultaneously from the same body water it has become clear however that the relationship is quite variable and for some time this variability was thought to be induced by a species effect although it has never been clear why that should be the case we studied sequential samples in enamel crowns of eight equid and cervid teeth from five different upper palaeolithic sites in peninsular italy encompassing an area with different geological units results suggest that 18 o c values are slightly attenuated compared to the 18 o p values in their seasonal profiles the observation is unexpected if both bioapatite mineral fractions precipitate simultaneously from body water one explanation could be diagenetic effects on the carbonate fraction the same pattern however has been observed in data comparing incremental 18 o c and 18 o p in modern mammal enamel crowns if confirmed attenuation of intra tooth 18 o c sequences compared to 18 o p variability would imply that seasonal climate inferences from the two proxies are not completely equivalent our results may also go some way in explaining the extent of variability amongst different sets of data in the 18 o p 18 o c relationship and suggest that the classical approach in the bioapatite community of using a constant offset between 18 op and 18 oc values needs to be approached with caution

intra tooth study of modern rhinoceros enamel δ18o is the difference between phosphate and carbonate δ18o a sound diagenetic test abstract the carbonate and phosphate oxygen isotopic difference 18 o c p has been suggested as a test for diagenetic alteration of isotope values in fossil apatite samples the generally accepted 18 o c p value for well preserved enamel is 9 only a few studies have focussed on the potential natural variability of this difference in modern and fossil mammal teeth the aim of this study is to document the value of the carbonate phosphate oxygen isotopic fractionation factor co3 po4 at an intra tooth level we measured the enamel phosphate and carbonate oxygen isotopic compositions of two upper molars m1 and m2 of rhinoceros unicornis following a sequence from the apex to the cervix of the crown the average co3 po4 is 1 0082 0 0007 the mean value of the 18 o c p difference is 8 4 0 7 close to the literature values given for other species however we also show that the values of the 18 o c p difference for r unicornis upper molars can vary on a 2 range in the same tooth we develop a physiological model to explain the origin of inter species and intra tooth 18 o c p difference and to understand their implications on the status of 18 o c p as a tool for identifying diagenesis the results imply that by increasing the dataset of phosphate and carbonate oxygen isotopic composition for modern mammal species we will be able to define a maximal and precise envelope corresponding to the well preserved samples and to check a possible species dependence on the 18 o c 18 o p relationship

how much did climate force the messinian salinity crisis quantified climatic conditions from pollen records in the mediterranean region the latest miocene 5 96 to 5 33 ma is characterised by an outstanding event the desiccation of the mediterranean sea messinian salinity crisis it has been suggested that this was caused by a tectonic event with no climatic change playing a role in desiccation quantifying the climate of the region during this period will help support or refute this hypothesis an effective method for reconstructing the climate from neogene pollen data is the climatic amplitude method based on the modern climatic requirements of plants to interpret fossil data it has been conceived especially for periods devoid of modern vegetation analogue twenty messinian to lower zanclean pollen sequences are now available in the peri mediterranean region most of them do not cover the whole messinian interval particularly those along the mediterranean shorelines where sedimentation was interrupted during the sea s desiccation in contrast sedimentation was almost continuous in such areas as the atlantic side of morocco along the adriatic coast including the po valley and to a lesser extent the black sea the mediterranean sites nonetheless provide a reliable if not a discontinuous record of vegetation variability in time and space a first examination of the pollen diagrams reveals a high regional variability controlled by local conditions and throughout the interval a southward increase in herb pollen frequency in contrast to the tree pollen frequency this indicates that open and probably dry environments existed in the southern mediterranean region prior to during and after the salinity crisis trees developed in areas close to mountains such as in the po valley in cerdanya and in the black sea region most variations observed in the pollen diagrams are constrained by fluctuations of pinus pollen amounts indicating eustatic variations climatic quantification from pollen data does not show obvious climatic changes due to the desiccation of the mediterranean sea especially in the dry and warm southwestern mediterranean area sicily southern spain and north africa at maccarone along the adriatic sea a decrease in temperatures of the coldest month and less importantly a decrease in mean annual temperatures corresponding to a drastic vegetation change are reconstructed these temperature variations are assumed to be controlled by regional environmental changes massive arrival of waters in this basin rather than to reflect cooling because some authors link the second phase of evaporite deposition to a period of global warming some migrations of plants probably occurred as a response to mediterranean desiccation but the climatic contrast which has probably existed at that time between the central mediterranean and the peripheral areas might be amplified climatic reconstruction from pollen data in the western mediterranean area shows that climate is not the direct cause of the mediterranean desiccation as the mediterranean region had experienced continuously high evaporation long before the crisis therefore the main factor leading to this event seems to be the successive closures of the betic and rifian corridors isolating the mediterranean sea from the atlantic ocean

an early pleistocene interglacial record from an intermontane basin of central italy scoppito l aquila abstract interdisciplinary investigations in the early pleistocene site of madonna della strada near scoppito l aquila central italy are presented complementing the information on large mammal remains recovered in the 1950s mammuthus meridionalis rhinoceros hippopotamus suid and small deer new fragmentary remains of an old rhinoceros individual are examined and discussed pollen analysis documents an interglacial forest phase with considerable frequencies of taxa presently extinct in the italian peninsula tsuga carya pterocarya and zelkova starting with an expansion of conifers progressively replaced by a mixed deciduous forest followed by an increase of mediterranean vegetation the abundance of extinct elements suggests an early pleistocene age older than the jaramillo subchron 1 07 ma the scarcity of picea and cedrus and the absence of liquidambar suggest that the record should be younger than mis 40 approx 1 3 ma this chronological setting indicates that hippopotamus antiquus was already present in italy before the jaramillo palaeomagnetic inversion

seasonal stable isotope evidence for a strong asian monsoon throughout the past 10 7 m y o of wet season rainfall was signi cantly morenegative 29 5 smow prior to 7 5 ma than after 26 5 smow if this change is attributable to a lessening of the amounteffect in rainfall this agrees with oral and soil geochemical datathat indicate increasing aridity beginning at 7 5 ma keywords tibetan plateau monsoon stable isotopes paleohydrology seasonality introductionthe tibetan plateau is the engine that drives the modern asianmonsoon by generating a high altitude region of low pressure in thesummer as the plateau heats and a region of high pressure in the winteras the plateau cools hastenrath 1991 during the summer warm airrises from the plateau pulling moist air off the ocean across the indiansubcontinent and into the highlands this results in heavy summer rain fall on the subcontinent the opposite occurs in the winter resultingin cold dry air spilling off the plateau and effectively excluding rainfrom the subcontinent thus the presence of a strong wet season dry season alternation implies the presence of a plateau broad and highenough to drive the monsoon the timing of the uplift of the plateau remains a matter of con siderable debate because there are few direct indicators of paleotopog raphy in the geologic record consequently past workers in tibet re lying on indirect indicators of uplift have proposed dates ranging from40 to 3 4 ma on the basis of initiation of potassic volcanism chunget al 1998 turner et al 1993 or extension on the plateau harrisonet al 1995 coleman and hodges 1995 changes in marine sedimen tation rates burbank et al 1993 sediment types rea et al 1998 or biota nigrini and caulet 1992 kroon et al 1991 and changesin stable carbon isotope and palynological patterns on the indian sub continent quade et al 1989 chen 1981 although different areasof the plateau may have risen at different times many workers haveinferred rapid simultaneous uplift of large areas of the plateau at 7 8ma by a process such as lithospheric delamination molnar et al 1993 this inference was based on the following approximately coevalphenomena a major change in plant communities of the indian sub continent quade et al 1989 and shifts in marine upwelling patternsthat are linked to an intense monsoon kroon et al 1991 althoughthere is strong evidence for signi cant climate change at 7 8 ma it isunclear whether this is the onset of the monsoon the oral transitionseems to have been a global rather than local phenomenon cerling etal 1997 and monsoonally driven upwelling may have already beenpresent by 10 12 ma nigrini and caulet 1992 kroon et al 1991 because there is an intimate association between the intense sea sonality of the modern monsoon and a high tibetan plateau and be cause evaporation can be unambiguously recognized in the d

pollen and mammals from the late early pleistocene site of saticula sant agata de goti benevento italy abstract a fluvio lacustrine succession was discovered in 1995 at saticula near sant agata de goti benevento below a thick volcaniclastic deposit sealed by the ignimbrite campana formation 39 ka vertebrate fossil remains and pollen were recovered in the excavated sections pollen analysis allowed recognition of two pollen zones the first being characterised by a quercus carya mixed deciduous forest which was probably present in the plain and on the slopes surrounding the caudina valley basin the following samples record a drastic decrease in carya pollen grains and the contemporary increase in herbs and pinus a more open environment established around the river shores due to a climate shift towards dryer conditions most of the vertebrate remains were found in the upper portion of the succession corresponding to the zone with reduced carya pollen the fossil mammal assemblage includes hippopotamus antiquus axis eurygonos megacerini indet equus suessenbornensis and stephanorhinus cf s hundsheimensis in addition a partial unerupted molar of an elephantid two hyena coprolites and fragments of rodent teeth were identified the high amount of carya at the base of the succession represents the most peculiar feature of the saticula floral record and was used as a reference for its chronological constraint comparison with other italian pollen successions allowed the saticula record to be tentatively ascribed to the late early pleistocene after that period carya was never recorded in such high amounts and gradually disappeared from the italian flora following a heterochronous latitudinal gradient the saticula mammal assemblage is in agreement with the chronological framework suggested by pollen data

pliocene climate variability northern annular mode in models and tree ring data the northern annular mode nam and its regional expression the north atlantic oscillation nao are the primary interannual oscillatory systems in the northern hemisphere in the modern climate nam has been linked with a number of weather extremes including large terrestrial temperature increases and extreme snowfalls its connection to climate is more controversial although a change in its behaviour between 1970 and 2000 coincided with rapid temperature increases in the northern hemisphere the north atlantic and nordic seas are a key component in pliocene climate showing the largest increases from modern sea surface temperature to understand these changes and the ability of climate models to reproduce them we must consider simulations of the nam here we show that existing mid pliocene simulations exhibit large changes to the mean state and variability in the north atlantic and a significant dampening of the nao through sensitivity experiments this change is primarily attributed to the impact of the lowering of the rocky mountains as the timing of rocky mountains uplift is still disputed simulations of the north atlantic region contain significant uncertainty particularly relating to interannual variability and its climate feedbacks new high temporal resolution climate proxy data is required to test these model reconstructions here we report new annual resolution data and an analysis of climate variability from fossil tree rings these fossils from sites in the canadian arctic provide support for a strong north atlantic oscillation during the pliocene

oxygen isotope fractionation between apatite and aqueous phase phosphate 20 45 c abstract replacement of biogenic caco3 by apatite is an important mode of authigenic apatite formation in marine sediments active along the peru margin today synthesis experiments mimicking this process were undertaken in abiotic inorganic systems in order to determine the oxygen o isotope fractionation between apatite and aqueous phase inorganic phosphate po4 aq caco3 solids were added to po43 solutions made with 18o labeled waters and o isotope fractionations between solid and aqueous phase po43 were determined in a series of experiments at 20 45 c results of 18o analyses of apatite synthesis systems indicate that o isotope fractionation between solid and aqueous phase po43 is 1 not affected by variations in water 18o values 2 initially non equilibrium and 3 relatively small 1 fractionations determined from long term up to 6 years room temperature experiments were 1 due to initial rapid precipitation short experimental run periods 1 week to 4 months resulted in fractionations between apatite and po4 aq that were initially reversed from those of long term experiments over time and with progressive recrystallization these fractionations evolved to reach values consistent with long term experiments

carbon and oxygen stable isotope compositions of late pleistocene mammal teeth from dolines of ajoie northwestern switzerland abstract fossils of megaherbivores from eight late pleistocene 14 c and osl dated doline infillings of ajoie nw switzerland were discovered along the transjurane highway in the swiss jura carbon and oxygen analyses of enamel were performed on forty six teeth of large mammals equus germanicus mammuthus primigenius coelodonta antiquitatis and bison priscus coming from one doline in boncourt 80 ka marine oxygen isotope stage mis5a and seven in courtedoux 51 27 ka late mis3 in order to reconstruct the paleoclimatic and paleoenvironmental conditions of the region similar enamel 13 c values for both periods ranging from 14 5 to 9 2 indicate that the megaherbivores lived in a c 3 plant dominated environment enamel 18 o po4 values range from 10 9 to 16 3 with a mean of 13 5 1 0 n 46 mean air temperatures mats were inferred using species specific 18 o po4 18 o h2o calibrations for modern mammals and a present day precipitation 18 o h2o mat relation for switzerland similar average mats of 6 6 3 6 c for the deposits dated to 80 ka and 6 5 3 3 c for those dated to the interval 51 27 ka were estimated this suggests that these mammals in the ajoie area lived in mild periods of the late pleistocene with mats only about 2 5 c lower than modern day temperatures

a model of fossil tooth and bone diagenesis implications for paleodiet reconstruction from stable isotopes abstract diagenesis of structural carbonate in biogenic apatite in the postmortem environment is modeled as a process of water mineral interaction both closed and open system model calculations suggest that 13 c of structural carbonate in biogenic apatite is much more resistant to diagenetic modification than 18 o apatite structural carbonate retains an original 13 c signal in closed system diagenesis for open systems 13 c of biogenic apatite with very low porosity such as tooth enamel can survive most diagenesis and retain a primary isotopic signature on the hand 18 o of structural carbonate in biogenic apatite may not be a reliable indicator of the original isotopic ratios except in a diagenetic system with low temperature and very low water biomineral ratio application of the model to teeth and carbonate cement in sediments from the badlands south dakota illustrates that 13 c values of enamel samples preserve the original signal whereas 13 c values of dentine represent varying extents of diagenesis 18 o values of fossil teeth may record an early or late part of their water biomineral interaction history during diagenesis

reconstructing the palaeoenvironments of the early pleistocene mammal faunas from the pollen preserved on fossil bones abstract we carried out a systematic investigation on the pollen content of sediment adhering to skeletal elements of large mammals which originate from the long lacustrine record of leffe early pleistocene of the italian alps three local faunas were discovered during mining activities along the intermediate part spanning from 1 5 to 0 95 ma of the basin succession the excellent pollen preservation allowed testing the reproducibility of the pollen signal from single skeletons a clear palaeoenvironmental patterning consistent with the ecological preferences of the considered mammal species emerged from the canonical correspondence analysis of pollen types diagnostic for vegetation communities edaphic factors related to seasonal river activity changes and to the development of swamp forests in the riverbanks are significantly associated to the occurrences of hippopotamus cf antiquus whereas finds of mammuthus meridionalis belong to fully forested landscapes dominated by conifer or mixed forests of oceanic warm to cool temperate climate rhinoceros habitats include variable forest cover under different climate states distinct cool temperate partially open vegetation could be recognized for large deer included cervalces cf carnutorum a palynostratigraphic correlation between individual spectra and a reference palynostratigraphic record allowed assignment of many fossil remains to a precise stratigraphic position this procedure also shown that the leffe local faunas include specimens accumulated under different environmental and climate states as a consequence of high frequency climate changes characterizing the late villafranchian early pleistocene

plio pleistocene floras of the vildstejn formation in the cheb basin czech republic a floristic and palaeoenvironmental review abstract plant fossil assemblages foliage fruits and seeds pollen wood from the pliocene and early pleistocene deposits in w bohemia the vildstejn formation of the cheb basin tachov cheb doma lice graben are newly analysed using several palaeoenvironmental methods with the aim to reconstruct palaeovegetation and palaeoclimatic changes floras of four subsequent stratigraphic levels show a decrease of exotic elements in the pliocene and a massive immigration of boreal elements in the early pleistocene vegetation changes start with broad leaved deciduous and mixed mesophytic forests and continue towards light forests of the mentioned types in areas of zonal to extrazonal habitats this vegetational change is characterised by an immigration of dry herbaceous and sclerophyllous elements wetland communities from higher positions in the profiles stepwise loose exotic components and point to cool temperate conditions similar to the present conditions palaeoclimatic signals show warmer and more humid conditions for the pliocene levels about 15 c of mean annual temperature 5 c of mean temperature of the coldest month and 25 c of mean temperature of the warmest month more than 900 mm of mean annual precipitation early pleistocene proxy data indicate the beginning of a cooler phase at the plio pleistocene boundary about 7 c of mean annual temperature and decreasing trend of precipitation but conditions not colder than those of the present day in the nw part of the bohemian massif

northern hemisphere glaciation and the evolution of plio pleistocene climate noise 1 deterministic orbital controls on climate variability are commonly inferred to dominate across timescales of 104 106 years although some studies have suggested that stochastic processes may be of equal or greater importance here we explicitly quantify changes in deterministic orbital processes forcing and or pacing versus stochastic climate processes during the plio pleistocene via time frequency analysis of two prominent foraminifera oxygen isotopic stacks our results indicate that development of the northern hemisphere ice sheet is paralleled by an overall amplification of both deterministic and stochastic climate energy but their relative dominance is variable the progression from a more stochastic early pliocene to a strongly deterministic late pleistocene is primarily accommodated during two transitory phases of northern hemisphere ice sheet growth this long term trend is punctuated by stochastic events which we interpret as evidence for abrupt reorganization of the climate system at the initiation and termination of the mid pleistocene transition and at the onset of northern hemisphere glaciation in addition to highlighting a complex interplay between deterministic and stochastic climate change during the plio pleistocene our results support an early onset for northern hemisphere glaciation between 3 5 and 3 7 ma and reveal some new characteristics of the orbital signal response such as the puzzling emergence of 100 ka and 400 ka cyclic climate variability during theoretical eccentricity nodes

stable isotope compositions of mammoth teeth from niederweningen switzerland implications for the late pleistocene climate environment and diet abstract oxygen and carbon isotope compositions of well preserved mammoth teeth from the middle wurmian 40 70 ka peat layer of niederweningen the most important mammoth site in switzerland were analysed to reconstruct late pleistocene palaeoclimatic and palaeoenvironmental conditions drinking water 18o values of approximately 12 3 0 9 were calculated from oxygen isotope compositions of mammoth tooth enamel apatite using a species specific calibration for modern elephants these 18 o h 2 o values reflect the mean oxygen isotope composition of the palaeo precipitation and are similar to those directly measured for late pleistocene groundwater from aquifers in northern switzerland and southern germany using a present day 18 o h 2 o precipitation air temperature relation for switzerland a mean annual air temperature mat of around 4 3 2 1 c can be calculated for the middle wurmian at this site this mat is in good agreement with palaeotemperature estimates on the basis of middle wurmian groundwater recharge temperatures and beetle assemblages hence the climatic conditions in this region were around 4 c cooler during the middle wurmian interstadial phase around 45 50 ka bp than they are today during this period the mammoths from niederweningen lived in an open tundra like c3 plant dominated environment as indicated by enamel 13c values of 11 5 0 3 and pollen and macroplant fossils found in the embedding peat the low variability of enamel 13c and 18o values from different mammoth teeth reflects similar environmental conditions and supports a relatively small time frame for the fossil assemblage

nursing weaning and tooth development in woolly mammoths from old crow yukon canada implications for pleistocene extinctions abstract this study investigates differences in the 13ccol 15n 13csc 18osc sr ca and ba ca values of juvenile and adult woolly mammoths mammuthus primigenius from old crow yukon canada the data indicate that nursing in woolly mammoths lasted at least three years and was associated with minimal decreases in 13ccol 0 2 large decreases in 13csc 1 5 and large increases in 15n 2 and 18osc 2 values sr ca and ba ca ratios suggest that woolly mammoth juveniles began consuming plant foods between 2 and 3 african elephant years of age much later than the initiation of weaning in modern elephants we hypothesize that delayed weaning was an adaptation to increased predation risk and decreased food quality quantity during the extended hours of darkness that occur in winter at high latitudes prolonged nursing and delayed weaning may have made mammoths particularly vulnerable to climatic stressors or human hunting

reconstructing the migration patterns of late pleistocene mammals from northern florida usa abstract we used analyses of the strontium isotope 87sr 86sr ratios of tooth enamel to reconstruct the migration patterns of fossil mammals collected along the aucilla river in northern florida specimens date to the late glacial period and before the last glacial maximum pre lgm deer and tapir displayed low 87sr 86sr ratios that were similar to the ratios of florida environments which suggest that these taxa did not migrate long distance outside of the florida region mastodons mammoths and equids all displayed a wide range of 87sr 86sr ratios some individuals in each taxon displayed low 87sr 86sr ratios that suggest they ranged locally while other animals had high 87sr 86sr ratios that suggest they migrated long distances 150 km outside of the florida region mastodons were the only taxa from this region that provided enough well dated specimens to compare changes in migration patterns over time pre lgm mastodons displayed significantly lower 87sr 86sr ratios than late glacial mastodons which suggests that late glacial mastodons from florida migrated longer distances than their earlier counterparts this change in movement patterns reflects temporal changes in regional vegetation patterns

coupled greenhouse warming and deep sea acidification in the middle eocene 1 the middle eocene climatic optimum meco is an enigmatic warming event that represents an abrupt reversal in long term cooling through the eocene in order to further assess the timing and nature of this event we have assembled stable isotope and calcium carbonate concentration records from multiple deep sea drilling project and ocean drilling program sites for the time interval between 43 and 38 ma revised stratigraphy at several sites and compilation of 18o records place peak warming during the meco event at 40 0 ma chron c18n 2n the identification of the 18o excursion at sites in different geographic regions indicates that the climatic effects of this event were globally extensive the total duration of the meco event is estimated at 500 ka with peak warming lasting 100 ka assuming minimal glaciation in the late middle eocene 4 6 c total warming of both surface and deep waters is estimated during the meco at the study sites the interval of peak warming at 40 0 ma also coincided with a worldwide decline in carbonate accumulation at sites below 3000 m depth reflecting a temporary shoaling of the calcite compensation depth the synchroneity of deep water acidification and globally extensive warming makes a persuasive argument that the meco event was linked to a transient increase in atmospheric pco2 the results of this study confirm previous reports of significant climatic instability during the middle eocene furthermore the direct link between warming and changes in the carbonate chemistry of the deep ocean provides strong evidence that changes in greenhouse gas concentrations exerted a primary control on short term climate variability during this critical period of eocene climate evolution

the middle eocene climatic optimum meco a multiproxy record of paleoceanographic changes in the southeast atlantic odp site 1263 walvis ridge the middle eocene climatic optimum meco 40 ma was a transient period of global warming that interrupted the secular cenozoic cooling trend we investigated the paleoceanographic paleoenvironmental and paleoecological repercussions of the meco in the southeast atlantic subtropical gyre ocean drilling program site 1263 tex86 and 18o records support an 4 c increase in surface and deepwater temperatures during the meco there is no long term negative carbon isotope excursion cie associated with the early warming consistent with other sites and there is no short term negative cie 50 kyr during the peak of the meco in contrast to what has been observed at some sites this lack of a cie during the peak of the meco at site 1263 could be due to poor sediment recovery or geographic heterogeneity of the 13c signal benthic and planktic foraminiferal mass accumulation rates markedly declined during meco indicating a reduction of planktic foraminiferal production and export productivity vertical 13c gradients do not indicate major changes in water column stratification and there is no biomarker or micropaleontological evidence that hypoxia developed we suggest that temperature dependency of metabolic rates could explain the observed decrease in foraminiferal productivity during warming the kinetics of biochemical reactions increase with temperature more so for heterotrophs than for autotrophs steady warming during meco may have enhanced heterotroph i e foraminiferal metabolic rates so that they required more nutrients these additional nutrients were not available because of the oligotrophic conditions in the region and the lesser response of primary producers to warming the combination of warming and heterotroph starvation altered pelagic food webs increased water column recycling of organic carbon and decreased the amount of organic carbon available to the benthos

astronomically forced climate evolution in a saline lake record of the middle eocene to oligocene jianghan basin china abstract following the early eocene climatic optimum some 50 million years ago the marine paleoclimate record indicates that a long interval of global cooling took place punctuated by a series of short term warming reversals and culminating with the glaciation of antarctica at the eocene oligocene transition we investigate a saline lake record from the qianjiang and jinghezhen formations jianghan basin china for the corresponding continental climate response a 20 25 myr long astronomical time scale is constructed based on 405 kyr orbital eccentricity cycle tuning of gamma ray gr series measured from the qianjiang and jinghezhen formations the halite rich interval between 41 40 4 ma correlates well with the middle eocene climate optimum recorded in the deep sea 18 o record confirming predominantly halite deposition during the warming silt mudstone rich intervals were deposited during 2 4 myr orbital eccentricity minima the evidence indicates a history of alternating fresh water humid cool and saline water dry hot lake cycles paced by 100 kyr orbital eccentricity cycles analysis of gr series from the deepest part of the lake indicates strong astronomical forcing of halite deposition throughout the middle late eocene and a shift to siliciclastic deposition and cooler climates at 33 9 ma early oligocene wet cool climate in the jianghan basin signals east asian summer monsoon intensification and a reduction from northwest winter monsoon in response to tibetan plateau uplift northern hemisphere summer insolation minima in the middle late eocene with temperatures that are 4 6 c higher than present may provide an analogy for near future climate change in jianghan basin

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

c and n stable isotope measurements on eurasian fossil mammals 40 000 to 10 000 years bp herbivore physiologies and palaeoenvironmental reconstruction abstract seventy seven specimens of fossil upper pleistocene early holocene woolly mammoth reindeer deer and bison from 17 different locations in eurasia have been measured for the nitrogen and carbon stable isotope composition of their collagen and for the carbon stable isotope composition of bioapatite the aim was 1 to check the existence of differences in n and c isotope ratios between and within different herbivore species mainly between mammoth and reindeer 2 to discuss these data in terms of animal physiology temporal and spatial distribution of animals and effects of climatic changes and 3 to obtain further information about the environmental changes that occurred in that area during the period considered a geographical variation from south west to north east in the 15n and or 13c values of collagen and bioapatite for all the herbivore species is apparent the most negative 13c values and the most positive 15n values being located in the north eastern area this was probably due to a different temperature and water stress on animals and plants and to a different plant availability the differences in 13c 12c and 15n 14n isotope ratios among species are mainly related to different food intake and different metabolic pathways it seems also that the diet of mammoths from north eastern siberia was higher in protein content compared with that of mammoths from the russian plain from this study it is clear that there was a rapid and important change in the amount of precipitation soon after the last glacial maximum the rainfall conditions around 40 000 and 30 000 years bp were probably similar to those existing around 10 000 years bp though lower than those existing after the glacial maximum

the preservation of glacial interglacial climatic signatures in the oxygen isotopes of elephant skeletal phosphate abstract phosphate 18o values 18op of modern elephant bone and teeth are found to vary linearly according to the 18o of local meteoric water 18omw a parameter with close ties to regional and local climatic conditions enamel dentine cementum and bone separates from individual fossil elephant specimens of late pleistocene age have op values which vary by up to elephant specimens the larger spread in the 18op values of the various skeletal phases for the fossil samples is interpreted as evidence for post depositional alterantion of primary 18op signatures of some if not all of these fossil skeletal components in the fossil samples investigated enamel and dentine phases have systematically lower 18o values than associated bone and cementum phases differential re equilibration with soil waters either by the wholesale replacement of primary apatite or by processes of isotopic exchange is suggested as a mechanism to account for the observed spread in the fossil phosphate 18o data

diagenesis and the reconstruction of paleoenvironments a method to restore original δ18o values of carbonate and phosphate from fossil tooth enamel abstract intra tooth 18 o variations within the carbonate 18 oc and phosphate 18 op components of tooth apatite were measured for miocene and pliocene hypsodont mammals from afghanistan greece and chad in order to evaluate the resistance of enamel to diagenetic alteration application of water apatite interaction models suggest that the different kinetic behaviours of the phosphate water and carbonate water systems can be used to detect subtle oxygen isotope disequilibria in fossil enamel when intra individual variations are considered selective alteration of the oxygen isotope composition from the carbonate component of afghan and greek enamels suggests inorganic isotopic exchange processes microbially induced isotopic exchange for phosphate is demonstrated for the first time in enamel samples from chad in association with extensive recrystallization in chad 18 op values were derived from partial isotopic exchange with fossil groundwater during early diagenesis mass balance calculations using average carbonate content in enamel as a proxy for recrystallization and the lowest 18 op value of dentine as a proxy for the isotopic composition of the diagenetic fluid indicate that diagenesis can alter 18 op by as much as 3 in some enamel samples this diagenetic alteration is also responsible for a decrease in intra individual variations of up to 1 in affected specimens the effects of diagenesis on 18 op values of fossil enamel are not systematic however and can only be estimated if sequential 18 op and 18 oc analyses are performed on fossil enamel and dentine reconstruction of large temporal or spatial scale paleoclimates based on 18 op analyses from mammalian teeth cannot be considered valid if enamel has been affected by bacterial activity or if the data cannot be corrected for diagenetic effects

ocean overturning since the late cretaceous inferences from a new benthic foraminiferal isotope compilation 1 benthic foraminiferal oxygen isotopic d 18 o and carbon isotopic d 13 c trends constructed from compilations of data series from multiple ocean sites provide one of the primary means of reconstructing changes in the ocean interior these records are also widely used as a general climate indicator for comparison with local and more specific marine and terrestrial climate proxy records we present new benthic foraminiferal d 18 o and d 13 c compilations for individual ocean basins that provide a robust estimate of benthic foraminiferal stable isotopic variations to 80ma andtentatively to 110ma first order variations ininterbasinal isotopicgradients delineate transitions from interior ocean heterogeneity during the late cretaceous 65 ma to early paleogene 35 65 ma homogeneity and a return to heterogeneity in the late paleogene early neogene 35 0 ma we propose that these transitions reflect alterations in a first order characteristic of ocean circulation the ability of winds to make water in the deep ocean circulate we document the initiation of large interbasinal d 18 o gradients in the early oligocene and link the variations in interbasinal d 18 o gradients from the middle eocene to oligocene with the increasing influence of wind driven mixing due to the gradual tectonic opening of southern ocean passages and initiation and strengthening of the antarctic circumpolar current the role of wind driven upwelling possibly associated with a tethyan circumequatorial current in controlling late cretaceous interior ocean heterogeneity should be the subject of further research

isotopic composition of precipitation in italy a first overall map abstract composite monthly samples of atmospheric precipitation were collected over different periods of time ranging from one to seven years at 77 different locations throughout italy these samples were measured for their oxygen and hydrogen isotopic composition to obtain basic information for hydrological and meteorological studies in this area on the basis of the results obtained a first map of the isotopic composition of precipitations in italy has been drawn up the main features of this map are the following 1 no isotopic latitudinal gradient has been found along the tyrrhenian coast from sicily to the italian french border despite the considerable range of latitude 2 a minor latitudinal gradient is found in the southeasternmost section of the country apulia partially favored by the local morphology 3 a marked shadow effect of the apennines is apparent along the southern section of the po valley and along the central section of the adriatic coast 4 the contribution of water vapor from the northernmost section of the adriatic sea affects the eastern and central sections of the po plain 5 the shadow effect of the alps is considerably smaller than expected 6 the isotopic vertical gradients calculated in nine different areas and based on groups of two to five different stations vary but are essentially close to about 0 2 100 m 7 when mean monthly temperature values were available their relationship with the isotopic composition of precipitation was found to be on average very poor 8 the relationship between mean 18o and mean d calculated for the collection locations shows shifts of both the slope and the deuterium excess when compared to the global meteoric water line these shifts are different for northern central and southern italy 9 in a few cases anomalously low monthly values suggest the existence of pronounced amount effects

oxygen isotope values of precipitation and the thermal climate in europe during the middle to late weichselian ice age abstract the oxygen isotope compositions of 28 mammoth tooth enamel samples from estonia latvia lithuania poland and denmark provide new quantitative records of the middle to late weichselian climate in northern europe the new 18 o data was combined with records of oxygen isotope values from earlier investigations on european mammoth tooth enamel and palaeogroundwaters to study the spatial patterns and temporal variations in the oxygen isotope composition of precipitation and the thermal climate over much of europe the reconstructed geographical distribution of 18 o in precipitation during 52 24 ka reflects the progressive isotopic depletion of air masses moving northeast consistent with a westerly source of moisture for the entire region and a circulation pattern similar to that of the present day regional long term average 18 o w values were 0 6 4 1 lower than at present the largest changes recorded for the currently maritime influenced southern sweden and the baltic region the application of regionally varied t slopes estimated from palaeogroundwater data and modern correlations yield reasonable estimates of glacial surface temperatures in europe and imply 2 9 c lower long term mean annual surface temperatures during the glacial period