oak leaves as biosensors of late neogene and early pleistocene paleoatmospheric co2 concentrations abstract complementary to the interpretation of 13 c values of biogenic carbonate and sedimentary organic carbon in marine sediments paleoatmospheric co 2 levels can be estimated by considering the inverse relationship between atmospheric co 2 concentration and stomatal parameters frequency size on leaves of land plants in woody plants the significance of this species specific physiological response to changing co 2 regimes is now repeatedly confirmed both experimentally and from historical sequences of leaves collected since the onset of industrialization a corollary of this relationship is that analysis of stomatal parameters on fossil leaves has the potential of determining changes in paleoatmospheric co 2 levels at different time scales well preserved cuticle remains of oak leaves from late miocene pliocene and early pleistocene sediments of the lower rhine embayment germany the netherlands give promise of extending the record of stomatal frequency response to the last 10 ma during intervals with warm temperate to subtropical climatic conditions oak leaves are characterized by a high stomatal resistance or low conductance to co 2 diffusion and low stomatal frequencies during cooler intervals we observe an opposite picture comparison with historical relations between co 2 concentration and stomatal properties suggests that paleoatmospheric co 2 concentrations were not significantly higher than during the last 200 years and fluctuated several times between 280 and 370 ppmv in covariation with contrasting regional climatic conditions on a global scale intervals with reduced co 2 levels match glacial pulses characterized by the occurrence of ice rafted detritus in high latitude oceanic sediments

sea surface temperature variability in the norwegian sea during the late pliocene linked to subpolar gyre strength and radiative forcing the mid piacenzian warm period 3 264 3 025 ma of the pliocene epoch has been proposed as a possible reference for future warm climate states however there is significant disagreement over the magnitude of high latitude warming between data and models for this period of time raising questions about the driving mechanisms and responsible feedbacks we have developed a new set of orbital resolution alkenone based sea surface temperature sst and ice rafted debris ird records from the norwegian sea spanning 3 264 3 14 ma the ssts in the norwegian sea were 2 3 c warmer than the holocene average likely caused by the radiative effect of higher atmospheric co2 concentrations there is notable obliquity driven sst variability with a range of 4 c shown by evolutive spectra the correlation of sst variability with the presence of ird suggests a common climate forcing acting across the nordic seas region changes of the sst gradient between the norwegian sea and north atlantic sites suggest that the subpolar gyre was at least as strong as during the holocene and that the northward heat transport by the north atlantic current was comparable

biologically available pb a method for ancient human sourcing using pb isotopes from prehistoric animal tooth enamel abstract this study analyzes pb isotopes combining biological ancient human and prehistoric animal teeth and geological soil leachate whole rock and rock leachate samples to determine the origins of prehistoric skeletal elements it exemplifies how the biologically available pb method assesses the early lifetime locations of ancient human populations using prehistoric animal teeth and the multivariate linear nature of pb isotope data lead isotopes provide a valuable technique in part due to the correlation between their six stable isotope ratios other studies have used pb isotopes for similar purposes but no clear method for determining a local range has yet been formally defined and tested the biologically available pb method uses many prehistoric animal tooth enamel samples to establish a baseline for local ratios in the region then compares their ratios linear patterning to human remains to test if they are non local the case study compares pb isotopes from prehistoric animal teeth human teeth and whole rocks from southwest arkansas these results are compared to animal samples from louisiana and mississippi and human data from illinois and new mexico soil leachates pb concentrations of tooth enamel and trace element analysis are used to assess contamination comparisons to southwest arkansas whole rock pb isotope ratios suggest they are too variable to be used for direct comparison to ancient human remains illustrating that prehistoric animal teeth are more appropriate for direct comparison to prehistoric human teeth the biologically available pb method provides a key analysis tool needed for studies of ancient human sourcing

the relative contribution of orbital forcing and greenhouse gases to the north american deglaciation understanding what drove northern hemisphere ice sheet melt during the last deglaciation 21 7 ka can help constrain how sensitive contemporary ice sheets are to greenhouse gas ghgs changes the roles of orbital forcing and ghgs in the deglaciation have previously been modeled but not yet quantified here for the first time we calculate the relative effect of these forcings on the north american deglaciation by driving a dynamical ice sheet model glimmer cism with a set of unaccelerated transient deglacial simulations with a full primitive equation based ocean atmosphere general circulation model famous we find that by 9 ka orbital forcing has caused 50 of the deglaciation ghg 30 and the interaction between the two 20 orbital forcing starts affecting the ice volume at 19 ka 2000 years before co2 starts increasing in our experiments a delay which partly controls their relative effect

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

a persistent and dynamic east greenland ice sheet over the past 7 5 million years 10be and 26al isotopic evidence in quartz sand from the seafloor shows that a dynamic east greenland ice sheet has existed for the past 7 5 million years understanding the growth and stability of the greenland ice sheet is a long standing priority in palaeoclimate research and one that is at the heart of modern discussion of sea level rise paul bierman and colleagues present marine records of cosmogenic isotopes and conclude that an ice sheet in east greenland was continuously eroding sediments over the past 7 5 million years although the method could miss transient deglaciations and cannot firmly distinguish between remnant and larger ice sheets the results are consistent with model simulations of a waxing and waning but continuously present regional ice sheet climate models show that ice sheet melt will dominate sea level rise over the coming centuries but our understanding of ice sheet variations before the last interglacial 125 000 years ago remains fragmentary this is because terrestrial deposits of ancient glacial and interglacial periods1 2 3 are overrun and eroded by more recent glacial advances and are therefore usually rare isolated and poorly dated4 in contrast material shed almost continuously from continents is preserved as marine sediment that can be analysed to infer the time varying state of major ice sheets here we show that the east greenland ice sheet existed over the past 7 5 million years as indicated by beryllium and aluminium isotopes 10be and 26al in quartz sand removed by deep ongoing glacial erosion on land and deposited offshore in the marine sedimentary record5 6 during the early pleistocene epoch ice cover in east greenland was dynamic in contrast east greenland was mostly ice covered during the mid to late pleistocene the isotope record we present is consistent with distinct signatures of changes in ice sheet behaviour coincident with major climate transitions although our data are continuous they are from low deposition rate sites and sourced only from east greenland consequently the signal of extensive deglaciation during short intense interglacials could be missed or blurred and we cannot distinguish between a remnant ice sheet in the east greenland highlands and a diminished continent wide ice sheet a clearer constraint on the behaviour of the ice sheet during past and ultimately future interglacial warmth could be produced by 10be and 26al records from a coring site with a higher deposition rate nonetheless our analysis challenges the possibility of complete and extended deglaciation over the past several million years

marked decline in atmospheric carbon dioxide concentrations during the paleogene the relation between the partial pressure of atmospheric carbon dioxide pco2 and paleogene climate is poorly resolved we used stable carbon isotopic values of di unsaturated alkenones extracted from deep sea cores to reconstruct pco2 from the middle eocene to the late oligocene approximately 45 to 25 million years ago our results demonstrate that pco2 ranged between 1000 to 1500 parts per million by volume in the middle to late eocene then decreased in several steps during the oligocene and reached modern levels by the latest oligocene the fall in pco2 likely allowed for a critical expansion of ice sheets on antarctica and promoted conditions that forced the onset of terrestrial c4 photosynthesis

the pacific subsurface countercurrents and an inertial model abstract the tsuchiya jets or subsurface countercurrents extend across the pacific ocean carrying 7 2 106 m3 s 1 eastward on each side of the equator mean meridional sections of potential temperature salinity neutral density anomaly and the square of buoyancy frequency are presented for the western central and eastern tropical pacific ocean these sections are used together with maps of depth and salinity on isopycnals as well as thickness between isopycnals to describe the evolution of the tsuchiya jets as they flow from west to east an inertial jet model is formulated in which conservation of the bernoulli function and potential vorticity combine with the eastward shoaling of the tropical pycnocline to dictate the jet structure this model jet is consistent with a number of features of the tsuchiya jets their roughly constant volume transports their advection of properties such as salinity and oxygen over long zonal distances their rapidity and narrowness their poleward shift from we

geological and archaeological implications of strontium isotope analysis of exposed bedrock in the chicxulub crater basin northwestern yucatan mexico the surface geology of the site of the chicxulub impact crater in northwestern yucatan mexico has not been studied extensively since the discovery of the crater almost two decades ago strontium isotope 87sr 86sr measurements in carbonate rock outcrops reveal near uniform strontium signatures of 0 70905 inside the ring of cenotes water filled sinkholes which represents the rim of the crater basin measured strontium isotope ratios were used to infer rock ages employing the marine sr isotope curve we estimate the age of the exposed limestone within the chicxulub crater basin to be late miocene to early pliocene representing the age of the youngest sediment fill discovery of a large terrain of near uniform strontium isotope ratios in northwestern yucatan offers new geoarchaeological opportunities to track ancient maya migration and determine sources of manufactured goods our results have implications for applying the sr isotope method to maya archaeological sites such as mayapan the last maya capital and chichen itza

different contamination styles of prehistoric human teeth at a swiss necropolis sion valais inferred from lead and strontium isotopes separate fractions of dentine and enamel of 12 individuals from the necropolis of sion valais switzerland have been analyzed for pb and sr isotope compositions the individuals span a time period of more than 1 ka from 5 2 ka b p to 4 1 ka b p and include middle neolithic upper neolithic bell beaker and old bronze age civilizations individuals were buried either into or close to dolmens or into soil at 4 different sites on the alluvial fan of the sionne stream a tributary of the rhone river isotopic composition of dentine and enamel pairs of the individuals indicate that teeth underwent post mortem contamination lead contamination is due to two different sources petrol and natural pb from soils the preponderance of either petrol or natural pb contamination in teeth depends on the burial sites differences in the content of pb retaining particles organic matter fe hydroxides clay minerals that depend largely on soil grain size are suggested to be responsible for the differential pb contamination at the investigated burial sites strontium contamination is stronger in individuals buried into or close to dolmens which are made of calc schist slabs despite post mortem contamination both pb and sr isotopes have allowed the identification of an individual s enamel with isotopic compositions significantly different from those of the local substratum suggesting his immigration to the sion area from a geologically different region this individual belongs to the bell beaker civilization which is considered to have immigrated into western europe and the mediterranean basin at the end of the neolithic systematic differences between enamel and dentine isotopic compositions of all other individuals analyzed suggest that they assimilated in vivo pb and sr from an area nearby to that in which they were buried

no extreme bipolar glaciation during the main eocene calcite compensation shift major ice sheets were permanently established on antarctica approximately 34 million years ago1 2 3 close to the eocene oligocene boundary at the same time as a permanent deepening of the calcite compensation depth in the world s oceans4 until recently it was thought that northern hemisphere glaciation began much later between 11 and 5 million years ago1 2 3 5 this view has been challenged however by records of ice rafting at high northern latitudes during the eocene epoch6 7 and by estimates of global ice volume that exceed the storage capacity of antarctica8 at the same time as a temporary deepening of the calcite compensation depth 41 6 million years ago9 here we test the hypothesis that large ice sheets were present in both hemispheres 41 6 million years ago using marine sediment records of oxygen and carbon isotope values and of calcium carbonate content from the equatorial atlantic ocean these records allow at most an ice budget that can easily be accommodated on antarctica indicating that large ice sheets were not present in the northern hemisphere the records also reveal a brief interval shortly before the temporary deepening of the calcite compensation depth during which the calcite compensation depth shoaled ocean temperatures increased and carbon isotope values decreased in the equatorial atlantic the nature of these changes around 41 6 million years ago implies common links in terms of carbon cycling with events at the eocene oligocene boundary4 and with the hyperthermals of the early eocene climate optimum3 10 11 our findings help to resolve the apparent discrepancy between the geological records of northern hemisphere glaciation6 7 8 and model results12 13 that indicate that the threshold for continental glaciation was crossed earlier in the southern hemisphere than in the northern hemisphere

on the causes of mid pliocene warmth and polar amplification the mid pliocene 3 to 3 3 ma ago is a period of sustained global warmth in comparison to the late quaternary 0 to 1 ma ago and has potential to inform predictions of long term future climate change however given that several processes potentially contributed relatively little is understood about the reasons for the observed warmth or the associated polar amplification here using a modelling approach and a novel factorisation method we assess the relative contributions to mid pliocene warmth from elevated co2 lowered orography and vegetation and ice sheet changes the results show that on a global scale the largest contributor to mid pliocene warmth is elevated co2 however in terms of polar amplification changes to ice sheets contribute significantly in the southern hemisphere and orographic changes contribute significantly in the northern hemisphere we also carry out an energy balance analysis which indicates that that on a global scale surface albedo and atmospheric emmissivity changes dominate over cloud changes we investigate the sensitivity of our results to uncertainties in the prescribed co2 and orographic changes to derive uncertainty ranges for the various contributing processes

late pliocene greenland glaciation controlled by a decline in atmospheric co2 levels it is thought that the northern hemisphere experienced only ephemeral glaciations from the late eocene to the early pliocene epochs about 38 to 4 million years ago and that the onset of extensive glaciations did not occur until about 3 million years ago several hypotheses have been proposed to explain this increase in northern hemisphere glaciation during the late pliocene here we use a fully coupled atmosphere ocean general circulation model and an ice sheet model to assess the impact of the proposed driving mechanisms for glaciation and the influence of orbital variations on the development of the greenland ice sheet in particular we find that greenland glaciation is mainly controlled by a decrease in atmospheric carbon dioxide during the late pliocene by contrast our model results suggest that climatic shifts associated with the tectonically driven closure of the panama seaway with the termination of a permanent el nino state or with tectonic uplift are not large enough to contribute significantly to the growth of the greenland ice sheet moreover we find that none of these processes acted as a priming mechanism for glacial inception triggered by variations in the earth s orbit

evidence for rapid climate change in north america during the latest paleocene thermal maximum oxygen isotope compositions of biogenic phosphate from the bighorn basin wyoming oxygen isotope records of cenozoic sea water temperatures indicate that a rapid warming event known as the latest paleocene thermal maximum lptm occurred during the otherwise gradual increase in world temperatures during the late paleocene and early eocene oxygen isotope analysis of the carbonate and phosphate components of hydroxyapatite found in mammalian tooth enamel and body scales of river dwelling fish from the bighorn basin in wyoming were made to investigate corresponding changes in the terrestrial climate a comparison of carbonate and phosphate isotope data from modern and fossil material indicates that some diagenetic alteration of the fossil material has occurred although systematically larger intra tooth ranges in the oxygen isotope composition of carbonate indicate that it is more likely to have been affected than phosphate carbonate and phosphate from the ecologically diverse mammals and fishes both record a shift to higher oxygen isotope ratios at the same time and of the same duration as the lptm these shifts reflect a change in the isotopic composition of regional precipitation which in turn provides the first evidence for continental climate change during the lptm assuming the present day relation between the oxygen isotope composition of precipitation and temperature applies to conditions in the past and that animal physiology and behavior is relatively invariant over time the isotopic shift is equivalent to an increase of surface temperature in western north america of several degrees this result is consistent with the magnitude of high latitude ocean warming and provides a basis for relating marine and terrestrial oxygen isotope records to records of terrestrial biotic change 1998 elsevier science b v all rights reserved

territorial mobility and subsistence strategies during the ebro basin late neolithic chalcolithic a multi isotope approach from san juan cave loarre spain abstract the use of isotopic analysis in human and animal remains from the holocene has proved to be a very useful tool to explore the exploitation and adaptation of past populations to different environments in this study we present isotopic analysis results of carbon nitrogen and strontium from the late neolithic chalcolithic site of san juan cave loarre spain we analysed 33 humans divided in adult and subadult groups and 16 animals recovered from the same archaeological context stable isotope analysis of carbon and nitrogen has allowed to distinguish an homogeneous subsistence pattern during the late neolithic chalcolithic transition the use of strontium isotopes 87 sr 86 sr in human dental enamel suggests 19 4 out of 21 are non local individuals based on comparison with the local bioavailable 87 sr 86 sr range calculated using microfauna teeth from the archaeological context modern plants and snails this new study gives information about late neolithic communities located in the north east of the iberian peninsula and it allows inference of the socio economic structure territorial mobility and individual provenance of humans

alkenone and boron based pliocene pco2 records abstract the pliocene period is the most recent time when the earth was globally significantly 3 c warmer than today however the existing pco2 data for the pliocene are sparse and there is little agreement between the various techniques used to reconstruct palaeo pco2 this disagreement coupled with the general low temporal resolution of the published records does not allow a robust assessment of the role of declining pco2 in the intensification of the northern hemisphere glaciation inhg and a direct comparison to other proxy records are lacking for the first time we use a combination of foraminiferal 11b and organic biomarker alkenone derived carbon isotopes proxies to determine the concentration of atmospheric co2 over the past 5 ma both proxy records show that during the warm pliocene pco2 was between 330 and 400 ppm i e similar to today the decrease to values similar to pre industrial times 275 285 ppm occurred between 3 2 ma and 2 8 ma coincident with the inhg and affirming the link between global climate the cryosphere and pco2

effects of diagenesis on strontium carbon nitrogen and oxygen concentration and isotopic composition of bone abstract paleodietary analysis based on variations in the trace element and stable isotopic composition of inorganic and organic phases in fossil bone depends on the assumption that measured values reflect in vivo values to test for postmortem alteration we measured 87 sr 86 sr 13 c 12 c 18 o 16 o and 15 n 14 n ratios and sr concentrations in modern and prehistoric 610 to 5470 yr old bones of animals with marine or terrestrial diets from greenland bones from modern terrestrial feeders have substantially lower sr concentrations and more radiogenic 87 sr 86 sr ratios than those from modern marine feeders this contrast was not preserved in the prehistoric samples which showed almost complete overlap for both sr concentration and isotopic composition in bones from the two types of animals leaching experiments x ray diffraction analysis and infrared spectroscopy indicate that alteration of the sr concentration and isotopic composition in prehistoric bone probably results from nearly complete exchange with groundwater oxygen isotope ratios in fossil apatite carbonate also failed to preserve the original discrimination between modern terrestrial and marine feeders the c isotope ratio of apatite carbonate did not discriminate between animals with marine or terrestrial diets in the modern samples even so the ranges of apatite 13 c values in prehistoric bone are more scattered than in modern samples for both groups suggesting alteration had occurred 13 c and 15 n values of collagen in modern bone are distinctly different for the two feeding types and this distinction is preserved in most of the prehistoric samples our results suggest that postmortem alteration of dietary tracers in the inorganic phases of bone may be a problem at all archaeological sites and must be evaluated in each case while collagen analyzed in this study was resistant to alteration evaluation of the possibility of diagenetic alteration of its isotopic composition in bones from other contexts is also warranted

the effect of diagenesis on oxygen isotope ratios of biogenic phosphates the effect of diagenesis on the oxygen isotope composition of ancient biogenic phosphates was evaluated by measuring different types of material from middle triassic localities in the southern alps dentin bone and tooth enamel of different taxa hosted by different rock types and metamorphosed to differing degrees were analyzed for their 18 o and 13 c values using a new microanalytical gc irmms technique the 18 o values of the majority of bone and bulk tooth samples were 18 to 19 permil smow with three samples below this range and one close to 20 permil in contrast samples of tooth enamel were 19 4 to 20 7 permil significantly higher than bone and bulk tooth without the enamel data the 18 to 19 permil data could be misinterpreted as primary only when the higher 18 o values of the enamel are considered is it apparent that the bulk data have undergone diagenesis and temperature estimates are 5 c lower than would otherwise be calculated alteration of bulk tooth is also seen in a miocene shark tooth where 18 o values of enamel are 3 permil higher than those of bulk tooth although enamel is routinely analyzed for paleoclimate work of herbivorous mammals bulk bone teeth or shells are almost exclusively used for older marine samples the results of the present study indicate that bulk data should be treated with caution

resolving archaeological populations with sr isotope mixing models strontium isotope analysis of tooth enamel is a useful provenancing technique to investigate the childhood origins and residential mobility of ancient people however where different geographical target regions have similar biosphere 87sr 86sr it is often difficult to resolve the 87sr 86sr ranges of two different groups of people and establish what constitutes the local range at each site here a multi period study is presented from the outer hebrides scotland and an investigation of neolithic and early bronze age populations from the yorkshire wolds ne england the aim is to demonstrate that despite complex human dietary strategies simple mixing systems with only two end members do occur in archaeological human populations in certain geological provinces and despite overlapping 87sr 86sr ranges it is possible to separate two populations based on the structure within the data set

the last domicile of the iceman from hauslabjoch a geochemical approach using sr c and o isotopes and trace element signatures abstract we present sr c and o isotope ratios and quantitative ratios of trace element ratios in the rib and the femur of the tyrolean iceman otzi the results from the rib and the femur are compared with those obtained from pre industrial historic human skull bone fragments collected in the late 19th century from charnel houses located on different geological backgrounds throughout north and south tyrol comparison of strontium isotope data from the bone fragments locates the iceman s domicile during the last 5 to 10 years of his life to the crystalline part of the central alps statistical analysis of the trace element ratios together with oxygen isotope results suggests that the iceman probably spent most of his last years in southern elevated part of the otztal however the results from iceman only represent those from a single individual and are not a representative average of a group it cannot therefore be established with absolute certainty that the original trace element signatures were conserved especially during the first stage of mummification our conclusions should therefore be regarded as tentative but nevertheless the best possible indication his domicile and a stimulus for further research

permanent el nino and the onset of northern hemisphere glaciations mechanism and comparison with other hypotheses 1 the tropical pacific transitioned from a permanent el nino state that is without the current equatorial zonal gradient of sea surface temperatures to one with an equatorial cold tongue in a process that started 4 ma during the early pliocene the latter stages of this transition around 2 75 ma marked the onset of northern hemisphere glaciations we explore the hypothesis that this onset of glaciation is causally linked to the development of the cold tongue guided by atmosphere general circulation model agcm simulations forced by various hypothesized climate influences a unique feature of our simulations is imposing permanent el nino conditions not by imposing sea surface temperatures anomalies directly but rather through changing the implied ocean heat transport in the slab ocean component of the agcm done in such a way as to maintain global ocean heat balance similar to previous studies we find increased near surface temperature conditions occur during simulated permanent el nino conditions at the locations of known ice sheet growth during glacial periods we establish that this tropical extratropical connection is mediated through atmospheric stationary waves a well known atmospheric pathway for today s el nino influence on north america the influence of the permanent el nino condition is compared through model simulations to other mechanisms proposed to date to explain the onset of glaciations at 2 75 ma changes in atmospheric carbon dioxide co2 concentrations closure of the panama seaway and changes in north pacific seasonality the exact comparison is done by calculating differences in the equilibrium line altitude at the known locations of ice sheet growth an approach that permits the translation of climate anomalies into a measurement of glaciation trends in terms of glacier mass balance we find that permanent el nino and atmospheric co2 are the leading influences in this comparison leading us to conjecture that the two influences combined determined the long term background conditions governing ice sheet growth within this long term background evolution however we additionally find that the exact timing of northern hemisphere glaciations is likely to have come from favorable orbital conditions our results regarding permanent el nino on northern hemisphere glaciations is however conditioned on a strong sensitivity of northern hemisphere climate changes to how the oceanic heat compensation to the permanent el nino is achieved

isotope domain mapping of 87sr 86sr biosphere variation on the isle of skye scotland abstract the potential of 87 sr 86 sr isotope composition for tracking and determining the origin of material whether it is humans animals water or wine can be fully realized only if high quality reference datasets are available against which to compare the unknowns this is currently not the case despite the rapid increase in 87 sr 86 sr based provenance studies of biosphere materials there are no well documented maps available most researchers resort to generating reference maps from a variety of geological datasets plus the analysis of sparse environmental9 samples a major reason for this lack of reference material is the investment needed to undertake systematic sampling and analysis over large areas a further problem is associated with the choice of proxy material as organisms differ in their habitat and exploitation of resources in this paper various approaches to isotope biosphere sampling are considered some of the problems are assessed the precision required for the study of human populations is discussed and a first attempt is made to condense all of the available information into an isotope package9 map the work is based on a study undertaken on the isle of skye in the inner hebrides and reduces the complexity of geological and isotope data into five main 87 sr 86 sr packages package 1 northern area 0 705 0 7092 package 2 ne coast 0 7082 0 7102 package 3 granitic rocks 0 716 0 720 package 4 metamorphic rocks 0 7092 0 7188 package 5 seawater 0 7092 0 005 2 the approach of trying to constrain the isotope composition of certain areas and or lithologies offers the possibility of extrapolating to other similar areas without having to sample at the original density

in search of homelands using strontium isotopes to identify biological markers of mobility in late prehistoric portugal this study uses strontium isotopes 87 sr 86 sr in dental enamel from burial populations related to the fortified chalcolithic settlement site of zambujal c 2800e1800 bc to distinguish the presence of nonlocal individuals zambujal is located in the estremadura region of portugal near the atlantic coast and has long been considered a central location of population aggregation craft production and trade during a time of increasing political centralization and social stratification until its eventually abandonment during the bronze age while it is assumed that population migration and long distance trade played an important role in the region s development little is known about the migration patterns of individuals or groups the results of this study find that nine percent 5 out of 55 of the total surveyed individuals can be classified as non local based on 87 sr 86 sr values distinct from the local bioavailable

final closure of panama and the onset of northern hemisphere glaciation abstract the greenland ice sheet is accepted as a key factor controlling the quaternary glacial scenario however the origin and mechanisms of major arctic glaciation starting at 3 15 ma and culminating at 2 74 ma are still controversial for this phase of intense cooling ravelo et al 1 a c ravelo d h andreasen m lyle a o lyle m w wara regional climate shifts caused by gradual global cooling in the pliocene epoch nature 429 2004 263 267 proposed a complex gradual forcing mechanism in contrast our new submillennial scale paleoceanographic records from the pliocene north atlantic suggest a far more precise timing and forcing for the initiation of northern hemisphere glaciation nhg since it was linked to a 2 3 c surface water warming during warm stages from 2 95 to 2 82 ma these records support previous models g h haug r tiedemann effect of the formation of the isthmus of panama on atlantic ocean thermohaline circulation nature 393 1998 673 676 2 claiming that the final closure of the panama isthmus 3 0 2 5 ma j groeneveld s steph r tiedemann d nurnberg d garbe schonberg the final closure of the central american seaway geology in prep 3 induced an increased poleward salt and heat transport associated strengthening of north atlantic thermohaline circulation and in turn an intensified moisture supply to northern high latitudes resulted in the build up of nhg finally culminating in the great irreversible climate crash at marine isotope stage g6 2 74 ma in summary there was a two step threshold mechanism that marked the onset of nhg with glacial to interglacial cycles quasi persistent until today

closure of the panama seaway during the pliocene implications for climate and northern hemisphere glaciation the panama hypothesis states that the gradual closure of the panama seaway between 13 million years ago 13 ma and 2 6 ma led to decreased mixing of atlantic and pacific water masses the formation of north atlantic deep water and strengthening of the atlantic thermohaline circulation increased temperatures and evaporation in the north atlantic increased precipitation in northern hemisphere nh high latitudes culminating in the intensification of northern hemisphere glaciation nhg during the pliocene 3 2 2 7 ma here we test this hypothesis using a fully coupled fully dynamic ocean atmosphere general circulation model gcm with boundary conditions specific to the pliocene and a high resolution dynamic ice sheet model we carry out two gcm simulations with closed and open panama seaways and use the simulated climatologies to force the ice sheet model we find that the models support the panama hypothesis in as much as the closure of the seaway results in a more intense atlantic thermohaline circulation enhanced precipitation over greenland and north america and ultimately larger ice sheets however the volume difference between the ice sheets in the closed and open configurations is small equivalent to about 5 cm of sea level we conclude that although the closure of the panama seaway may have slightly enhanced or advanced the onset of nhg it was not a major forcing mechanism future work must fully couple the ice sheet model and gcm and investigate the role of orbital and co2 effects in controlling nhg

modelling pliocene warmth contribution of atmosphere oceans and cryosphere the relative role of the atmosphere oceans and cryosphere in contributing towards middle pliocene warmth ca 3 ma bp is investigated using the hadcm3 coupled ocean atmosphere general circulation model the model was initialised with boundary conditions from the usgs prism2 data set and a pliocene atmospheric co2 level of 400 ppmv and run for 300 simulated years the simulation resulted in a global surface temperature warming of 3degreesc compared to present day in contrast to earlier modelling experiments for the pliocene surface temperatures warmed in most areas including the tropics 1 5degreesc compared with present day the model predicts a general pattern of ocean warming 1 5degreesc in both hemispheres to a depth of 2000 m below which no significant differences are noted sea ice coverage is massively reduced up to 90 the flow of the gulf stream north atlantic drift is up to 100 mm s 1 greater in the pliocene case analysis of the model predicted meridional streamfunction suggests a global pattern of reduced outflow of antarctic bottom water aabw up to 5 sv a shallower depth for north atlantic deep water formation and weaker thermohaline circulation 3 sv the decrease in aabw occurs mainly in the pacific rather than atlantic ocean model diagnostics for heat transports indicate that neither the oceans nor the atmosphere are transporting significantly more heat in the pliocene scenario rather these results indicate that the major contributing mechanism to global pliocene warmth was the reduced extent of high latitude terrestrial ice sheets 50 reduction on greenland 33 reduction on antarctica and sea ice cover resulting in a strong ice albedo feedback these results highlight the need for further studies designed to improve our knowledge regarding pliocene terrestrial ice configurations

warmer tropics during the mid pliocene evidence from alkenone paleothermometry and a fully coupled ocean atmosphere gcm 1 traditional reconstructions of sea surface temperatures ssts produced by the pliocene research interpretations and synoptic mapping prism group indicate that mid pliocene surface ocean temperatures were unchanged or slightly cooler than modern at the tropics and low latitudes and significantly warmer at higher latitudes particularly in the north atlantic this change in the latitudinal pattern of ssts has been attributed to enhanced meridional ocean heat transport generated by more vigorous surface ocean gyres and or thermohaline circulation thc this study derives new sst estimates using the alkenone paleothermometer in the pacific ocean these estimates combined with published alkenone sst data from two atlantic sites are located in tropical and subtropical regions where the distribution of prism sites is sparse a fully coupled ocean atmosphere general circulation model oagcm running for the mid pliocene was also used to predict sst significant differences are noted between absolute prism ssts interpolated to our core locations and alkenone derived ssts these differences may be related to errors in the prism and alkenone paleothermometry estimates or to regional differences between localities where data was collected however the available alkenone and model based sst estimates are consistent in the sign of temperature change they predict and provide the first indication of warmer ssts during the mid pliocene in the tropics and subtropics this contrasts with prism s estimates of unchanged or slightly cooler ssts for the same geographical regions the pattern of ssts produced by alkenone estimates and modeling is not characteristic of that produced by enhanced meridional ocean heat transport or thc instead the pattern is similar to that which might be expected as a result of higher concentrations of atmospheric co2 which would act to warm the oceans at the tropics and other latitudes furthermore model diagnostics indicate that reduced sea ice and terrestrial ice sheet extents and a strong ice albedo feedback played a major role in forcing mid pliocene warmth further work aimed at validating these conclusions should concentrate on expanding the mid pliocene sst data set particularly at low latitudes as well as undertaking model model comparisons to assess model dependency of the results

residential mobility and social identity in the periphery strontium isotope analysis of archaeological tooth enamel from southeastern arabia a b s t r a c t strontium isotope analysis represents an effective means of assessing mobility and reconstructing geographic residence patterns in archaeological populations this biogeochemical technique was utilized to test the hypothesis that burgeoning interregional exchange networks and the occurrence of exotic grave goods in local tombs would correspond with a highly mobile population and a considerable immigrant presence during the umm an nar 2700e2000 bc period in the uae this region has been considered peripheral relative to larger civilizations in mesopotamia and the indus valley but played an important role as a major supplier of copper for the persian gulf individuals n 100 from six monumental umm an nar tombs mowaihat tell abraq umm an nar island i ii v unar 1 were selected to evaluate the geographic origins of tomb members mean 87 sr 86 sr ratios from local individuals interred at mowaihat 0 708863 0 000014 1s n 12 tell abraq 0 708873 0 000020 1s n 27 umm an nar island 0 708902 0 000079 1s n 33 and unar 1 0 708805 0 000065 1s n 25 all display little isotopic variability indicative of a population that was not highly mobile however coupled with archaeological evidence three immigrants from tell abraq n 2 and mowaihat n 1 identi ed by deviant strontium values suggest that this region was actively engaged in interregional interaction despite claims that these tombs acted as visible markers of territoriality legitimized by local ancestors buried within them the presence of non locals suggests that as commerce became increasingly important de nitions of kinship and social identity may have become more exible to better meet the needs of the local community and those with whom they interacted

permanent el nino like conditions during the pliocene warm period during the warm early pliocene 4 5 to 3 0 million years ago the most recent interval with a climate warmer than today the eastern pacific thermocline was deep and the average west to east sea surface temperature difference across the equatorial pacific was only 1 5 0 9 c much like it is during a modern el nino event thus the modern strong sea surface temperature gradient across the equatorial pacific is not a stable and permanent feature sustained el nino like conditions including relatively weak zonal atmospheric walker circulation could be a consequence of and play an important role in determining global warmth

increased sensitivity of the plio pleistocene northwest pacific to obliquity forcing abstract insolation driven changes in poleward heat transport and changes in greenhouse gas concentrations can explain aspects of the rise of obliquity paced climate variability during the pliocene pleistocene transition based on an alkenone based sea surface temperature sst reconstruction of the kuroshio current extension kce we propose here that emergence of this region as the primary locus of ocean atmosphere heat transfer in the pacific ocean promoted northern hemisphere glaciation nhg our record shows that with intensification of nhg at 2 7 ma the kce cooled 2 4 c during glacial intervals likely in nh winter spring these high amplitude 41 kyr sst cycles slightly lead o 18 variations ruling out global ice volume changes as the primary cause the lead of sst over o 18 cycles matches the phasing between these two proxies observed in the tropics supporting changes in co2 concentrations as a unifying mechanism of ocean surface temperature change however the amplitude of the kce sst cycle is twice that of the tropical records pointing to an additional regional process we infer that cooling of the north pacific sea surface by the east asian winter monsoon and associated westerlies intensified during glacial intervals this transfer of heat and moisture from the ocean to the atmosphere potentially furthered glacial formation by accelerating snow fall in north america therefore these results might also support a role for tropical extratropical heat balance in enhancing glacial growth via the obliquity pacing

a thermomechanical model of ice flow in west antarctica this study uses a three dimensional thermo mechanical model to investigate the internal flow dynamics of the west antarctic ice sheet wais the model allows ice thickness flow and temperature to interact freely its domain is prescribed as that of the present day grounded wais realistic present day climatic and topographical boundary conditions are employed the analysis of a series of experiments pays particular attention to the location and dynamics of concentrations of ice flow ice streams underlying topographic troughs are crucial in determining the strength and location of these concentrations of flow the flow pattern generated by subglacial troughs is made more distinct by the inclusion of ice flow temperature coupling the inclusion of sliding leads to the generation of limit cycles in the ice flow they are concentrated around the present day ice streams b and c of the siple coast and have a period of 5 to 10 ky there appears to be competition between several preferred ice flow pathways in this area the two end members of the flow regime are a strong ice stream c with a weakened ice stream a b complex and strong ice streams a and b with a dormant ice stream c ice streams appear to require ice discharges above a certain threshold in order to maintain frictional heat generation and fast flow individual ice streams can therefore interact through changes in catchment area size a reduction in catchment area reduces the volume of ice entering a stream and can cause stagnation as the amount of frictional heating falls

eocene continental climates and latitudinal temperature gradients global climate during the mesozoic and early cenozoic is thought to have been warmer than at present but there is debate about winter temperatures paleontological data indicate mild temperatures even at high latitudes and in mid latitude continental interiors whereas computer simulations of continental paleoclimates produce winter temperatures closer to modern levels foliar physiognomy and floristic composition of 23 eocene floras from the interior of north america and australia indicate cold month means generally 2 c even where the mean annual temperature mat was

forcing of late cenozoic northern hemisphere climate by plateau uplift in southern asia and the american west geologic evidence indicates that net vertical uplift occurred on a large kilometer scale and at accelerating rates during the middle and late cenozoic in plateaus of southern asia and the american west based on this evidence general circulation model sensitivity tests were run to isolate the unique effects of plateau uplift on climate the experiments simulated significant climatic changes in many places some far from the uplifted regions the basic direction of most of these simulated responses to progressive uplift is borne out by changes found in the geologic record winter cooling of north america northern europe northern asia and the arctic ocean summer drying of the north american west coast the eurasian interior and the mediterranean winter drying of the north american northern plains and the interior of asia and changes over the north atlantic ocean conducive to increased formation of deep water the modeled changes result from increased orographic diversion of westerly winds from cyclonic and anticyclonic surface flow induced by summer heating and winter cooling of the uplifted plateaus and from the intensification of vertical circulation cells in the atmosphere caused by exchanges of mass between the summer heated and winter cooled plateaus and the mid latitude oceans disagreements between the geologic record and the model simulations in alaska and the southern rockies and plains may be related mainly to the lack of narrow mountain barriers in the model orography taken together the observed regional trends comprise much of the pattern of late cenozoic climatic deterioration in the northern hemisphere that culminated in the plio pleistocene ice ages the success of the uplift sensitivity experiment in simulating the correct pattern and sign of most of the observed regional climatic trends points to uplift as an important forcing function of late cenozoic climatic change in the northern hemisphere at time scales longer than orbital variations however the modest amplitude of the uplift induced cooling simulated at high latitudes indicates a probable need for additional climatic forcing

insights into immigration and social class at machu picchu peru based on oxygen strontium and lead isotopic analysis abstract the inca empire ad 1438 1532 made common practice of relocating individuals households and entire communities throughout their expansive realm for different reasons depending on subjects assigned social class reconstructing patterns of immigration at inca period sites could therefore permit some estimation of the social class es among their constituents and thereby provide insights into the functional dynamics of inca political economy however this is a difficult endeavor using only archaeological lines of evidence this study presents oxygen strontium and lead isotopic results from the well preserved well contextualized skeletal population n 74 from the inca site of machu picchu peru isotopic data are used to reconstruct patterns of immigration at the site which are in turn used to directly estimate the social class of the population the resulting isotopic data are widely distributed with no apparent modality matching the expected distribution of a particular class of nonelite retainers a novel application of multivariate statistics coupled with geological and faunal isotopic reference data also permits tentative estimation of individuals regions of origin this study provides empirical and analytical frameworks for future research in reconstructing residential movement and class dynamics in the late prehistoric andes

late cenozoic history of the polar north atlantic results from ocean drilling abstract dsdp odp drilling in the northern north atlantic reveals that so far the onset of northern hemisphere cooling deduced from the occurrence of ice rafted debris ird in deep sea sediments can be traced back to the middle miocene the greenland ice sheet has probably the longest history on the northern hemisphere leg 151 site 909 fram strait recovered a unique continuous sediment record dating from early middle miocene the composition of the coarse fraction indicates that the oldest ird pulses are documented around 14 ma in the fram strait site 909 and around 12 6 ma on the voring plateau leg 104 site 642 in the norwegian greenland sea fram strait site 909 indicates a further stepwise increase of northern hemisphere cooling by serveral ird pulses during late miocene between 10 8 and 8 6 ma around 7 2 6 8 and 6 3 ma which ultimately led to a drastic intensification of northern hemisphere glaciation during plio pleistocene the deep sea sediment records show that plio pleistocene strengthening of ird pulses have been observed since approximately 4 0 ma in the westernmost norwegian greenland sea and labrador sea by contrast strengthening of ird pulses are observed at approximately 3 2 2 7 ma on the eastern side of the norwegian greenland sea including the barents sea margin sediment composition and physical properties of the drilled mostly terrigenous sections reveal that orbital parameters have controlled major aspects of shallow and deep water environments with frequency domains related to 41 ka periods of obliquity dominant in the pre glacial miocene pliocene and early quaternary and to 100 ka periods of eccentricity dominant during the past 600 000 700 000 years the stratigraphy of ice rafted material reveals a frequently and rapidly changing history of the dynamics of various segments in ice sheets around the norwegian greenland sea it is particularly evident from the composition of the ice rafted material that the eurasian ice sheets delivered ird to the eastern part of the norwegian greenland sea whereas greenland source areas are represented in the drill sites of the east greenland continental margin and in the labrador sea the stratigraphic sequences on the yermak plateau suggest that the svalbard ice sheet may have extended far to the north prior to oxygen isope stage 16 but not since then invasions of temperate atlantic waters during interglacials can be observed as short lived and rather irregular events it never reached the area off eastern greenland except during the pliocene interval when tundra floras were able to develop on north eastern greenland and planktonic foraminifers suggesting the presence of temperate water masses in the fram strait as been documented in the drill sites from the yermak plateau

biotic and geochemical evidence for a global latitudinal shift in ocean biogeochemistry and export productivity during the late pliocene during the late pliocene 3 to 2 5 ma oceanic records of opal and c37 alkenone accumulation from around the world show a secular shift towards lower values in the high latitudes and higher values in the low and mid latitudes these shifts are broadly coincident with the intensification of northern hemisphere glaciation and are suggestive of changes in export productivity with potential implications for pliocene atmospheric carbon dioxide concentrations the interpretation of a global latitudinal shift in productivity however requires testing because of the potential uncertainties associated with site to site comparisons of records that can be influenced by highly nonlinear processes associated with production export and preservation here we assess the inferred pliocene latitudinal productivity shift interpretation by presenting new records of c37 alkenone accumulation from ocean drilling program odp site 982 in the north atlantic and biotic assemblages calcareous nannoplankton from this site and odp site 846 in the eastern tropical pacific our results corroborate the interpretation of c37 alkenone accumulation as a proxy for gross export productivity at these sites indicating that large scale productivity decreases at high latitudes and increases at tropical sites are recorded robustly we conclude that the intensification of northern hemisphere glaciation during the late pliocene was associated with a profound reorganisation of ocean biogeochemistry

comments on richards et al journal of archaeological science 35 2008 strontium isotope evidence of neanderthal mobility at the site of lakonis greece using laser ablation pimms we present an evaluation of the laser ablation sr isotope data reported by richards et al 2008 for a neanderthal tooth recovered from a site in greece based on an alternative and analytically more robust method of correcting for isobaric interferences present during the analysis the tooth appears to be isotopically homogenous and within uncertainty of the value for modern seawater if this is the case then contrary to the migration model proposed by richards et al 2008 the neanderthal individual may have actually been a coastal dweller and lived within the vicinity of the find site

strontium isotopes of human remains from the san martin de dulantzi graveyard alegria dulantzi alava and population mobility in the early middle ages abstract strontium isotope analysis of human remains from san martin de dulantzi alegria dulantzi alava spain graveyard has been used to establish mobility patterns during the early middle ages some archaeological human remains had germanic grave goods through radiogenic strontium isotope analysis local origin individuals and immigrants were differentiated archaeological human bone samples exhibit 87sr 86sr 0 70779 0 70802 values similar to domestic fauna isotope composition indicating local origin of individuals or long residence time in the region comparing these data with tooth enamel values two groups of immigrants from distinctive geological environment were established the dulantzi population constituted mainly a local society with influxes of immigrants the foreign individuals are distributed through the studied period of time suggesting that migration movements were limited in number isotopic signatures indicating mainly local individuals linked to grave goods with archaeological attribution to germanic origin question the previous ethnic paradigm

patterns of diagenesis in bone i the effects of site environments abstract we have measured a suite of diagenetic parameters for several populations of archaeological bones buried in a number of northwest european sites since the last ice age these are the structural damage due to microbes changes in bone micro and macro porosity protein content a measure of the crystallinity of hydroxyapatite as reflected in the phosphate infra red spectrum peak splitting and a measure of the carbonate content as given by the ratio of carbonate to phosphate infra red absorption peaks the results provide a database that clearly characterises the patterns which are often site dependent of diagenetic change in buried bone our main conclusions are that individual site hydrology appears to have a strong influence on the outcome of bone preservation and that porosity is the most effective single diagenetic parameter which both determines and reflects the preservation of bone in the burial environment

pleistocene geochemical stratigraphy of the borehole 1317e iodp expedition 307 in porcupine seabight sw of ireland applications to palaeoceanography and palaeoclimate of the coral mound development stable isotopes and element compositions of the fine grained matrix were measured for iodp expedition 307 hole u1317e drilled from the summit of challenger mound in porcupine seabight northeast atlantic to explore the palaeoceanographic and palaeoclimatic background to development of the deep water coral mound the 155 m long mound section was divided into two units by an unconformity at 23 6 mbsf unit m1 2 6 1 7 ma and unit m2 1 0 0 5 ma results from 519 specimens show a difference in 13c value between unit m1 0 6 to 5 0 and unit m2 1 0 to 1 0 but such a distinct difference was not seen in 18o values 1 0 2 5 caco3 content 40 60 wt sr ca ratio 2 0 8 0 mmol mol 1 and mg ca ratio 10 0 20 0 mmol mol 1 through the mound positive 18o and negative 13c shifts at the mound base are consistent with the oceanographic changes in the northeast atlantic at the beginning of the quaternary the positive 13c regression in unit m2 suggests a linkage to the mid pleistocene intensified glaciation in the northern hemisphere warm mediterranean upper core water of mediterranean outflow water eastern north atlantic water and cold labrador sea water of north atlantic deep water are key oceanographic features that cause spikes and shifts in stable isotope and element composition however the stable isotope values of the sediment matrix could not primarily record the glacial interglacial eustatic temperature change but indirectly indicate current regimes of the intermediate oceanic layer where the coral mound grew similarly elemental ratios and caco3 content may not represent the productivity and temperature of surface sea water respectively but superpose the fractions from both surface and bottom water it is concluded that palaeoceanographic change coupled to the pleistocene glacial interglacial cycles is a key control on the geochemical stratigraphy of the matrix sediments of the carbonate mound developed in porcupine seabight copyright 2011 john wiley sons ltd

migration and mobility at the late lapita site of reber rakival sac watom island using isotope and trace element analysis a new insight into lapita interaction in the bismarck archipelago abstract this paper uses strontium isotope 87 sr 86 sr oxygen isotope 18 o and ba sr trace element data in archaeological tooth enamel samples to investigate migration and mobility at the late lapita site of sac watom island in the bismarck archipelago previous archaeological models have identified lapita mobility at a community level using obsidian distribution patterns and changes in ceramic design whereas isotope and trace element data can potentially reconstruct prehistoric mobility on an individual level human and pig teeth were sampled from sac and a selection of human teeth were included from the late post lapita site of lifafaesing tanga islands as a geographic geological comparison the results indicate that there is a large amount of isotopic variation in the bismarck archipelago which is useful for identifying non local individuals and possibly determining their origins one human individual and several pigs were suggested as coming from elsewhere in the region three potentially separate locations were identified for the non local pigs it is argued using the data from sac that late lapita communities in the bismarck archipelago were more mobile than previously assumed the potential for identifying individual migrants in a lapita context are discussed in terms of assessing the more subtle aspects of lapita society in the southwest pacific islands

mid pliocene warmth stronger greenhouse and stronger conveyor abstract three million years ago prior to the onset of northern hemisphere glaciation global mean temperatures may have been as much as 3 5 c warmer than at present we present evidence based on the carbon isotopic composition of marine organic matter that atmospheric co2 levels at this time were on average only about 35 higher than the preindustrial value of 280 ppm we also present carbon isotopic evidence for stronger thermohaline circulation in the atlantic ocean during the warmest intervals and propose that the north atlantic conveyor belt may act as a positive feedback to global warming by enhancing sea ice retreat and decreasing high latitude albedo based on our results it seems unlikely that the mid pliocene warm period was a doubled co2 world

diagenesis in prehistoric bone problems and solutions abstract post depositional chemical alteration or diagenesis in prehistoric human bone is the major problem in the use of trace element analyses for dietary reconstruction following a review of recent studies of diagenesis we discuss means for evaluating post depositional chemical change in bone and for removing such contaminants three different procedures are described which reflect current efforts to evaluate and reduce the effects of diagenesis these include 1 mechanical cleaning 2 chemical cleaning through acid washing and 3 washing with a reducing agent these procedures usually remove major contaminants leaving significant potential of trace element analyses for the investigation of past diet

a permanent el nino like state during the pliocene the pliocene may have been characterized by permanent el nino like conditions initial modeling studies suggest that this may have contributed to pliocene warmth the termination of this state may have influenced northern hemisphere glaciation nhg we use the hadley centre coupled model version 3 to examine the role of the oceans and ocean structure on pliocene warmth a permanent el nino like state is not predicted annual mean sea surface temperatures in the eastern equatorial pacific at ocean drilling program sites 847 and 851 increase by 1 71 c and 1 15 c respectively however el nino southern oscillation events are clearly expressed by the model sensitivity tests indicate that a prescribed permanent el nino like condition increases annual global mean surface temperatures by a maximum of 0 6 c if the pliocene was characterized by such a condition it is questionable that it provided a major contribution to global warmth and therefore unlikely that the termination of this state contributed significantly to the onset of nhg

plio pleistocene increase of erosion rates in mountain belts in response to climate change here we review an ensemble of observations that point towards a global increase of erosion rates in regions of elevated mountain belts or otherwise high relief since the onset of northern hemisphere glaciation about 2 3 ma during that period of earth s history atmospheric co2 concentrations may have dropped and global climate cooled and evolved towards high amplitude oscillating conditions that are associated with the waxing and waning of continental ice sheets in the northern hemisphere we argue for a correlation between climate change and increased erosion rates and relief production which we attribute to some combination of the observed cooling onset of glaciation and climatic oscillation at orbital timescales in our view glacial erosion played a major role and is driven by the global cooling furthermore analyses of the sedimentary fluxes of many mountain belts show peaks of erosion during the transitions between glacial and inter glacial periods suggesting that the variable climatic conditions have also played a role

rare earth elements and sr and nd isotopic compositions of dissolved and suspended loads from small river systems in the vosges mountains france the river rhine and groundwater abstract the aim of this study is to characterize the evolution of the rare earth elements ree in non mature streams from small catchment areas in the vosges mountains downstream to more mature plain rivers including the river rhine the dissolved load ree distribution patterns of the low ph vosges streams are very different from those of high ph plain rivers indicating that different physico chemical parameters control ree transport in these different water systems the plain rivers and groundwater show similar ree distribution patterns with a strong negative ce anomaly and heavy rare earth element hree enrichment in addition the river rhine has a positive gd anomaly which is of anthropogenic origin similar to the world s major rivers the light rare earth element lree enrichment in the plain rivers is mainly ph controlled their sm nd and 143 nd 144 nd isotope ratios are close to average continental crust values this is not the case for the less evolved non mature and low ph vosges streams their high sm nd and 143 nd 144 nd ratios but low 87 sr 86 sr ratios suggest that chemical alteration of accessory middle rare earth element mree enriched minerals such as apatites from rocks in the catchment area control the ree abundances of these waters a comparison of the dissolved load ree distribution patterns with those of the principal lithologies in the corresponding drainage basins illustrates that especially the eu anomalies of the vosges streamlets are strongly lithology dependent leaching experiments indicate that the suspended load is isotopically very inhomogeneous the ree distribution patterns of the suspended load leachates have no similarities with those of the corresponding dissolved load indicating that the leachable reservoir not only contains adsorbed ree but also ree from leachable mineral phases their 143 nd 144 nd sm nd and 87 sr 86 sr ratios support this suggestion being always higher and lower respectively than those of their corresponding dissolved loads they rather point to the presence of relic primary apatite in the leachable portion of the suspended load the flat paas normalized ree distribution patterns the high 87 sr 86 sr and low 143 nd 144 nd isotopic ratios of the corresponding residues suggest secondary silicate phases such as clay minerals in the residual phase of the suspended load leachates and corresponding residual phases define alignments in the sm nd isochron diagram whose slopes define ages ranging between 200 and 390 ma indicating that the mineral phases in the suspended load retain some memory of their primary precursor minerals in the hercynian granitic source rocks

the geographic distribution of sr isotopes from surface waters and soil extracts over the island of bornholm denmark a base for provenance studies in archaeology and agriculture abstract in this paper we report the sr isotope signatures and sr al and na concentrations of 30 surface waters lakes ponds and rivers creeks and 19 soil sample extracts from the island of bornholm denmark and present a categorized 87 sr 86 sr value distribution map that may serve as a base for provenance studies including archaeological migration and authenticity proof for particular food products the sr isotopic compositions of surface waters range from 87 sr 86 sr 0 7097 0 7281 average 0 7175 0 0049 1 whereas 0 1 m hno 3 0 05 m hno 3 and 0 01 m cacl 2 soil extracts range from 87 sr 86 sr 0 7095 0 7197 and define somewhat lower but statistically indistinguishable averages of 0 7125 0 003 1s these compositions are lower than the values expected from the precambrian granitoid basement 87 sr 86 sr 0 758 0 944 and from the overlying mainly clastic paleozoic sediments combined sr isotope composition vs sr na and al concentration relationships of soil extracts imply that lowering of the isotopic composition of leachable sr on bornholm results as a consequence of significant admixture to this fraction of sr deposited as marine salts aerosols and that rainwater only has a minor influence on the sr budget of the surface waters positively correlated al na and 1 sr vs 87 sr 86 sr relationships in soil extracts and surface waters indicate that the surface run off on bornholm is characterized by two predominant sources namely marine aerosols sea salts with high sr and low 87 sr 86 sr values and a source with lower sr delivering radiogenic sr to the surface waters which we equate with sr leached from the products of mineral weathering soils a feasibility study for using sr isotopic compositions of surface waters and soil extracts as a proxy for bioavailable sr signatures was performed with a few samples collected in the vicinity of the eleventh century ad ndr grodbygard cemetery site in sw bornholm from where sr isotope compositions of modern fauna samples and tooth enamel of humans buried in the cemetery have been reported waters and soil extracts studied herein from around this site range from 87 sr 86 sr 0 7104 0 7166 and correspond to sr compositions extracted from snail shells in this area which span a range of 87 sr 86 sr 0 7095 0 7160 some human tooth enamel is characterized by more radiogenic values 87 sr 86 sr up to 0 718 which points to a possible provenance of these humans from the granite gneiss terrain in the north of the island and or to immigration of these humans in their childhood from other places for example from mainland sweden to bornholm if the total compositional range of 87 sr 86 sr 0 709 0 718 n 44 recorded in human enamel from the ndr grodbygard site is considered representative for the variation of bioavailable sr on bornholm then our soil leachate and surface water data entirely covers this range we therefore propose that the combination of sr isotope analyses of surface waters and soil leachates are an easy fast and relatively cost efficient way to characterize a local bioavailable 87 sr 86 sr signature and consequently propose that the overall average of 87 sr 86 sr 0 7153 0 0048 1 n 50 can be taken as a band for bioavailable sr fractions suitable to discriminate between local and non local signatures in provenance studies in the field of archaeology and for food and plant authenticity control in agricultural applications

radiogenic and stable strontium isotopes in provenance studies a review and first results on archaeological wood from shipwrecks abstract different approaches are used to study wood provenance but most of them are based on tracers in wood that are generally controlled by climatic factors the strontium isotopic ratio 87 sr 86 sr in trees and soils is related to the signature of the local bedrock despite being used in diverse archaeological studies sr isotopes have rarely been used to trace the provenance of archaeological wood and especially wood from shipwrecks in addition recent analytical advances have allowed the detection of mass dependent fractionation of sr isotopes during biogeochemical processes as reflected in the variation of 88 86 sr values between different environmental materials the 88 86 sr values could be used in conjunction with the 87 sr 86 sr isotope ratio to improve constraints on the sources of sr in the archaeological materials being studied this paper discusses the potential and limitations of using both of these sr isotope ratios to trace the provenance of wood from shipwrecks we review the 87 sr 86 sr and 88 86 sr variations in rocks waters soils plants and other living organisms and discuss how to determine the local sr isotopic signature of potential sites we also compile a list of known wood post mortem modifications in seawater possible implications in terms of the modification of the original sr isotope ratios of wood during storage in seawater are illustrated through preliminary observations this paper points out some limitations and perspectives for using sr isotopes in provenancing wood from shipwrecks and suggests future research to test and apply this approach for tracing the origin of archaeological wood

role of tropics in changing the response to milankovich forcing some three million years ago appeared in regions that today have intense oceanic upwelling the eastern equatorial pacific and the coastal zones of southwestern africa and california there was furthermore a significant change in the earth s response to milankovich forcing obliquity signals became large but those associated with precession and eccentricity remained the same the latter change in the earth s response can be explained by hypothesizing that the global cooling during the cenozoic affected the thermal structure of the ocean it caused a gradual shoaling of the thermocline around 3 ma the thermocline was sufficiently shallow for the winds to bring cold water from below the thermocline to the surface in certain upwelling regions this brought into play feedbacks involving

the origin of the juch uypampa cave mummies strontium isotope analysis of archaeological human remains from bolivia previous analyses of strontium isotopes from human bone and teeth have identified diverse patterns of residential mobility in the south central andes during the middle horizon ad 500e1100 during this time the large polity of tiwanaku exerted great influence over what are now southern peru northern chile northwestern argentina and bolivia recently five naturallymummified individuals were discovered in the cave of juch uypampa in the pulacayo region of southern bolivia although these individuals were buried with a number of fine tiwanaku style grave goods as well as non tiwanaku items the burial site is isolated and does not conform to the pattern of large tiwanaku affiliated cemeteries and residential sites outside of the lake titicaca basin strontium isotope analysis was performed on enamel from two adult men and bone from a third adult male in order to test the hypotheses that one or more of the males was from either the tiwanaku heartland in the lake titicaca basin the chilean oasis of san pedro de atacama which contains a series of cemeteries with tiwanaku style grave goods or the local area in which they were buried results show that two individuals likely spent their childhood in the local area where they were interred while the third man probably spent at least the last twenty years of his life in that region before being buried there this raises interesting questions regarding the nature of tiwanaku influence in southern bolivia and the relationship between the juch uypampa mummies and the tiwanaku polity 2005 elsevier ltd all rights reserved

the contribution of orbital forcing to the progressive intensification of northern hemisphere glaciation in this study we reconstruct the timing of the onset of northern hemisphere glaciation this began in the late miocene with a significant build up of ice on southern greenland however progressive intensification of glaciation did not begin until 3 5 3 ma when the greenland ice sheet expanded to include northern greenland following this stage we suggest that the eurasian arctic and northeast asia were glaciated at approximately 2 74 ma 40 ka before the glaciation of alaska 2 70 ma and about 200 ka before significant glaciation of the north east american continent 2 54 ma we also review the suggested causes of northern hemisphere glaciation tectonic changes such as the uplift of the himalayan and tibetan plateau the deepening of the bering strait and the emergence of the panama isthmus are too gradual to account entirely for the speed of northern hemisphere glaciation we therefore postulate that tectonic changes may have brought global climate to a critical threshold but the relatively rapid variations in the earth s orbital parameters and thus insolation triggered the intensification of northern hemisphere glaciation this theory is supported by computer simulations which despite the relative simplicity of the model and the approximation of some factors e g using a linear carbon dioxide scenario neglecting the geographical difference between the pliocene and the present suggest that it is possible to build up northern hemisphere ice sheets between 2 75 and 2 55 ma by varying only the insolation controlled by the orbital parameters c 1998 elsevier science ltd all rights reserved

late miocene atmospheric co2 concentrations and the expansion of c4 grasses the global expansion of c4 grasslands in the late miocene has been attributed to a large scale decrease in atmospheric carbon dioxide co2 concentrations this triggering mechanism is controversial in part because of a lack of direct evidence for change in the partial pressure of co2 pco2 and because other factors are also important determinants in controlling plant type distributions alkenone based pco2 estimates for the late miocene indicate that pco2 increased from 14 to 9 million years ago and stabilized at preindustrial values by 9 million years ago the estimates presented here provide no evidence for major changes in pco2 during the late miocene thus c4 plant expansion was likely driven by additional factors possibly a tectonically related episode of enhanced low latitude aridity or changes in seasonal precipitation patterns on a global scale or both

assessing life history from commingled assemblages the biogeochemistry of inter tooth variability in bronze age arabia abstract stable isotopes represent a remarkable means of assessing the life histories of individuals in the archaeological record primarily by taking advantage of multiple skeletal tissues that form and remodel throughout life however this methodological tool also has the potential to provide crucial information on the life histories of individuals represented only by commingled fragmentary and otherwise isolated human skeletal remains particularly when more traditional methods of evaluation are not possible in this study a sequential analysis of radiogenic strontium 87sr 86sr and stable oxygen 18o isotopes of associated molars from the in situ mandibular or maxillary fragments of 19 commingled individuals from multiple bronze age tombs in the united arab emirates was undertaken in order to examine temporal changes in mobility at the level of the individual the majority of individuals display little difference in inter tooth isotope ratios suggesting a general lack of residential mobility between early childhood and late adolescence an unexpected result given abundant evidence artifactual and written for a population actively engaged in both regional and interregional trade in the third millennium bc however two individuals from the emirate of fujairah demonstrate disparate inter tooth 87sr 86sr values likely indicative of some migration event which calls into question the supposed cultural isolation of the region during the second millennium bc

stable carbon cycle climate relationship during the late pleistocene a record of atmospheric carbon dioxide co2 concentrations measured on the epica european project for ice coring in antarctica dome concordia ice core extends the vostok co2 record back to 650 000 years before the present yr b p before 430 000 yr b p partial pressure of atmospheric co2 lies within the range of 260 and 180 parts per million by volume this range is almost 30 smaller than that of the last four glacial cycles however the apparent sensitivity between deuterium and co2 remains stable throughout the six glacial cycles suggesting that the relationship between co2 and antarctic climate remained rather constant over this interval

the role of co2 decline for the onset of northern hemisphere glaciation the pliocene pleistocene transition ppt from around 3 2 to 2 5 million years ago ma represented a major shift in the climate system and was characterized by a gradual cooling trend and the appearance of large continental ice sheets over northern eurasia and north america paleo evidence indicates that the ppt was accompanied and possibly caused by a decrease in atmospheric co2 but the temporal resolution of co2 reconstructions is low for this period of time and uncertainties remain large therefore instead of applying existent co2 reconstructions we solved an inverse problem by finding a schematic co2 concentration scenario that allows us to simulate the temporal evolution of key climate characteristics in agreement with paleoclimate records to this end we performed an ensemble of transient simulations with an earth system model of intermediate complexity from which we derived a best guess transient co2 scenario for the interval from 3 2 to 2 4 ma that gives the best fit between the simulated and reconstructed benthic 18o and global sea surface temperature evolution our data constrained co2 scenarios are consistent with recent co2 reconstructions and suggest a gradual co2 decline from 375 425 to 275 300 ppm between 3 2 and 2 4 ma in addition to a gradual decline the best fit to paleoclimate data requires the existence of pronounced co2 variability coherent with the 41 kyr 1 kyr 1000 years obliquity cycle in our simulations the long term co2 decline is accompanied by a relatively abrupt intensification of northern hemisphere glaciation at around 2 7 ma this is the result of a threshold behaviour of the ice sheets response to gradual co2 decrease and orbital forcing the simulated northern hemisphere ice sheets during the early pleistocene glacial cycles reach a maximum volume equivalent to a sea level drop of about 40 m both ice volume and benthic 18o are dominated by 41 kyr cyclicity our simulations suggest that before 2 7 ma greenland was ice free during summer insolation maxima and only partly ice covered during periods of minimum summer insolation a fully glaciated greenland comparable to its present day ice volume is modelled only during glacial maxima after 2 7 ma and more continuously after 2 5 ma

the geographic distribution of strontium isotopes in danish surface waters a base for provenance studies in archaeology hydrology and agriculture abstract in this paper sr isotope signatures are reported for 192 surface water lakes ponds and rivers creeks samples from within denmark and an isotope distribution map is presented that may serve as a base for provenance applications including archaeological migration studies ground water surface water seawater interaction contamination monitoring and potentially for agricultural applications including cases of authenticity proof for particular food products the sr isotopic compositions of surface waters range from 87sr 86sr 0 7078 to 0 7125 average 0 7096 0 0016 2 this average value lies above the range of 87sr 86sr values between 0 7078 and 0 7082 expected from late cretaceous to early tertiary oligocene limestones which form the dominant bedrock type in a nw se trending belt in denmark the elevated 87sr 86sr signatures 0 7095 are explained by additions to the surface waters of radiogenic sr predominantly derived from the near surface weathering and wash out of quarternary glaciogenic tills and soils deposited and formed during and after the last two ice age stages saale and weichsel the sr isotopic compositions and concentrations of the surface waters can therefore best be modeled by a two component mixing involving carbonaceous bedrock and glaciogenic cover sediments as the two predominant sr sources a feasibility study for using sr isotopic compositions of surface waters as a proxy for bio available sr signatures was conducted in a representative test area on zealand land of legends lejre where there is no use and application of commercial fertilizers it is demonstrated that the sr isotopic signatures of lake waters from within this area are slightly higher but statistically still indistinguishable from the average value defined by snail shells and soil leachates considered to characterize the true bio available sr in combination with results from other studies this is interpreted to reflect the wash out of sr with a higher 87sr 86sr signature released by weathering in the topsoils into the saturated water tables a component which is consequently not readily transferred into the shallow rooting plants and into small herbivores feeding on them since drinking water is a likely important source of sr uptake of humans and larger animals the contention is that a surface water isotopic composition can potentially characterize the bio available component relevant for human and carnivorous large animals spline functions and ordinary linear kriging were used for modeling the geographic distribution of bio available sr isotopes over territorial denmark as expected based on the two source mixing scenario the water 87sr 86sr ratio contour maps with some notable exceptions neither mirror the pre quarternary bedrock geology nor a pleistocene soil type distribution map of denmark as a conservative suggestion the use of the average 87sr 86sr ratio of 0 7096 0 0015 2 is recommended as an average for bio available sr from within denmark bornholm excluded for human and larger animals and as a confidence band for distinguishing local from non local signatures in archaeological provenance studies the study also reveals that the average 87sr 86sr ratio of 0 7088 defined from soil extracts and small herbivores lies approximately 0 15 lower than that defined by the surface waters the authors recommend using this lower value as a local non local discriminator for food and plant authenticity control in agricultural applications

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

social differentiation and land use at an early iron age princely seat bioarchaeological investigations at the glauberg germany excavations at the late hallstatt early la tene 6th 4th century bc princely seat of the glauberg hesse germany revealed exceptionally furnished graves in monumental mounds simple inhumations in associated ditches and non normative burials of up to eight individuals in conical storage pits the study presented here addresses bioarchaeological characteristics of these burials and their implications for social differentiation and the sphere of influence of the princely seat it includes osteological adna and multi isotope analyses of 27 human individuals and faunal remains one of the outstandingly rich graves tumulus 1 grave 1 contained the skeleton of a young man the prince who consumed a superior diet based on c3 plants that also included considerable amounts of animal protein the oxygen isotope composition of his enamel is characteristic for the study area while the strontium isotope data reflect connections beyond the near environs of the princely seat and a conceivable non local origin the individuals in the conical pits had numerous joint lesions indicating a strenuous lifestyle they lack evidence for maternal relationships and differ from the prince and other iron age burials due to substantial millet consumption and rather low shares of animal protein their heterogeneous strontium isotope ratios suggest connections to the western wetterau area where settlements may have formed the economic hinterland of the glauberg hillfort the results reflect both the role of the princely seat in the wider regional context and early iron age social complexity

cosmopolitan catterick isotopic evidence for population mobility on rome s northern frontier in order to investigate how the population diversity at major romano british urban centres compared to small towns and military outposts we conducted multi isotope carbon nitrogen oxygen and strontium analyses of bones 42 individuals and teeth 26 individuals of human skeletons from cataractonium roman catterick in north yorkshire u k the results suggest a markedly less diverse population at catterick than at the larger towns significant differences are observed between burials from the town and fort area and the suburb of bainesse to the south and it is suggested that these reflect a shift to more localised recruitment for the roman army in the late roman period isotope data for the bainesse eunuch an unusual 4th century burial that has been interpreted as the remains of a transvestite priest of cybele are not ultimately conclusive but consistent with origins in southern britain or areas with a similar climate abroad this paper also presents strontium isotope data for modern vegetation samples from 17 sites in the catterick northern vale of york area which contribute to a continuing effort to map the biosphere 87sr 86sr variation in britain

isotopic paleoceanography of the caribbean and east pacific role of panama uplift in late neogene time comparisons of carbon isotopic data on benthic foraminifera from deep sea drilling project sites 502 western caribbean and 503 eastern pacific indicate that the difference between the atlantic and the pacific in the per mil enrichment in carbon 13 of total dissolved carbon dioxide increased about 6 million years ago and again 3 million years ago when the difference reached the modern level 1 per mil comparisons of planktonic foraminiferal oxygen isotopic data for the caribbean and the pacific suggest that the salinity of caribbean surface waters began increasing 4 million years ago possibly in response to shoaling of the panama isthmus these results suggest that modern circulation patterns in the caribbean and eastern pacific developed by 3 million years ago in concert with changing tectonic climatic and biogeographic patterns

as a dietary indicator in modern and archaeological bone strontium isotope ratios 87sr86sr in human and animal bone are inherited via foodstuffs from rocks in the areas in which an individual lived if such an area includes more than one rock type with differing 87sr86sr or is coastal region with terrestrial 87sr86sr different from that of the sea then bone strontium isotope ratio measurements provide a measure of the relative importance of foods from each isotopic zone in the southwestern cape of south africa marine and coastal terrestrial areas covered by marine sands should yield foods with 87sr86sr close to the marine average while the cambrian and pre cambrian shales and sandstones of the hinterland ought to be enriched in 87sr from radioactive decay of 87rb during the considerable time elapsed since they were laid down analyses of modern animal bones show that these patterns do prevail furnishing us with a new means of reconstructing prehistoric diets preliminary measurements on archaeological human material recovered from coastal shell midden sites apparently reflect heavy reliance on coastal foods however these bones have been shown to be contaminated with diagenetic marine strontium from the shells in the middens experiments on faunal specimens show that diagenetic strontium can be removed by repeated washing in acetic acid sodium acetate buffer mineral with 87sr86sr similar to the burial environment dissolves first while subsequent washes remove strontium with different 87sr86sr for two coastal human skeletons however the marine coastal terrestrial nature of the isotopic signature remains further experimental work is required in order to establish the limits of the technique however a combination of the solubility profile method and strontium isotope analysis promises to provide a powerful tool for reconstructing palaeodiets

the last glacial cycle transient simulations with an aogcm a number of transient climate runs simulating the last 120 kyr have been carried out using famous a fast atmosphere ocean general circulation model aogcm this is the first time such experiments have been done with a full aogcm providing a three dimensional simulation of both atmosphere and ocean over this period our simulation thus includes internally generated temporal variability over periods from days to millennia and physical detailed representations of important processes such as clouds and precipitation although the model is fast computational restrictions mean that the rate of change of the forcings has been increased by a factor of 10 making each experiment 12 kyr long atmospheric greenhouse gases ghgs northern hemisphere ice sheets and variations in solar radiation arising from changes in the earth s orbit are treated as forcing factors and are applied either separately or combined in different experiments the long term temperature changes on antarctica match well with reconstructions derived from ice core data as does variability on timescales longer than 10 kyr last glacial maximum lgm cooling on greenland is reasonably well simulated although our simulations which lack ice sheet meltwater forcing do not reproduce the abrupt millennial scale climate shifts seen in northern hemisphere climate proxies or their slower southern hemisphere counterparts the spatial pattern of sea surface cooling at the lgm matches proxy reconstructions reasonably well there is significant anti correlated variability in the strengths of the atlantic meridional overturning circulation amoc and the antarctic circumpolar current acc on timescales greater than 10 kyr in our experiments we find that ghg forcing weakens the amoc and strengthens the acc whilst the presence of northern hemisphere ice sheets strengthens the amoc and weakens the acc the structure of the amoc at the lgm is found to be sensitive to the details of the ice sheet reconstruction used the precessional component of the orbital forcing induces 20 kyr oscillations in the amoc and acc whose amplitude is mediated by changes in the eccentricity of the earth s orbit these forcing influences combine to first order in a linear fashion to produce the mean climate and ocean variability seen in the run with all forcings

differential diagenesis of strontium in archaeological human dental tissues the investigation of prehistoric human migration from the measurement of sr isotope ratios within preserved tissue is critically dependent on the preservation of biogenic sr a number of recent studies have involved isotope ratio measurements on samples of archaeological tooth and bone but doubt remains as to the extent of diagenesis in various skeletal tissues and the effectiveness of procedures designed to decontaminate them the authors have compared sr abundance and isotope ratios in enamel and dentine from archaeological teeth in order to assess the integrity of the biogenic sr signal preserved within the respective tissues it is concluded that enamel appears in most cases to be a reliable reservoir of biogenic sr but that dentine and by implication bone is not the diagenesis of dentine is highly variable even between burials within a single site for the majority of teeth dentine diagenesis was not simply by addition of soil derived sr but involved substantial sometimes complete turnover of the original biogenic material it is suggested that for most of the samples investigated current decontamination techniques may not have been effective in isolating biogenic sr from dentine similar considerations are likely to apply to archaeological and fossil bone but the possibility arises to use dentine and enamel measurements to assess the effectiveness of decontamination procedures which may then be used for bone

strontium isotope systematics of hydrothermal vein minerals in deposits of west germany vein minerals in west germany hosted by crystalline basement rocks and paleozoic and mesozoic sedimentary rocks are characterized by87sr 86sr ratios which indicate continental derivation of sr incorporated into the minerals neither mantle derived sr nor prominent contribution of this element from sea water except for the strontianites of munsterland can be substantiated by the data presented

an evaluation of nitrogen porosimetry as a technique for predicting taphonomic durability in animal bone to date direct measurements of bone porosity have been used primarily to quantify the degree of diagenetic alteration qualitative zooarchaeological observations over many years have suggested that for equivalent burial conditions the bones of different taxa degrade at different rates and that even within a single skeleton systematic variation often occurs given that freedom of access of water to the internal bone surface is likely to be an important factor in controlling the rate of chemical alteration we postulate that the initial porosity of a bone may be an important factor in predicting the rate of degradation to test this we have used nitrogen porosimetry as a technique for comparing the total pore volume and size distribution of pores between a selection of anatomical elements taken from a range of modern animals commonly represented on european archaeological sites we show that the bones of modern domestic pig are on average more porous than those of other ungulates and should therefore be likely to degrade faster after burial systematic differences in porosity are also shown between different anatomical elements from a single individual and between adult and juvenile bone however we also show that porosity measurements are affected by sample storage and preparation methodology particularly freezing variations in bone porosity between different skeletal elements and taxa necessitate careful sample selection and matching in order to minimize variation we conclude that despite these restrictions direct measurement of variations in bone porosity shows good potential for contributing to a predictive model for bone diagenesis

mobility of bell beaker people revealed by strontium isotope ratios of tooth and bone a study of southern bavarian skeletal remains in order to contribute to the continuing discussion of the mobility of the late neolithic bell beaker people 69 skeletons from southern bavaria were analyzed for the 87sr 86sr isotope ratios in tooth enamel and compact bone whereas sr isotope ratios in the enamel of the first permanent molar match the sr isotopic composition at the place of early childhood the respective value in the adult femoral bone matches the sr isotope ratio characteristic of the place of residence over the last few years prior to death significant differences between 87sr 86sr in these tissues indicate that 17 5 25 of these individuals changed residence during their lifetime the overall direction of the migration according to archaeological finds from the area was toward the southwest a relative surplus of migrating females and two cases of evidence for migration in children argue for the movement of small groups exogamy might explain the higher numbers of immigrating females with regard to current information on migration rates in prehistory the southern bavarian bell beaker people were indeed highly mobile especially since the archaeometric method used in this study is likely to underestimate movement

determining the local 87sr 86sr range for archaeological skeletons a case study from neolithic europe measurement of strontium isotopes in archaeological skeletons is an effective technique for characterizing prehistoric mobility however interpretation of the results can be highly sensitive to small changes in the determined local 87sr 86sr signature at an archaeological site because the local range is often defined as within 2 s d from the mean 87sr 86sr value in archaeological human bones the susceptibility of bones to diagenesis may lead to significant overestimates in the number of non locals at a particular site tooth enamel on the other hand is highly resistant to postmortem biochemical alteration and it is found that 87sr 86sr in archaeological enamel samples from animals of neolithic germany provide a useful alternative estimate for the local range

diagenesis of strontium in fossil bone a reconsideration of nelsonet al 1986 abstract in experiments on marine animal fossils that had been buried in terrestrial sediments nelsonet al 1986 geochimica et cosmochimica acta50 1941 1949 reported that the strontium sr of prehistoric bone had nearly completely exchanged with that of the burial environment and therefore cannot be used for paleodietary reconstruction however sealyet al 1991 journal of archaeological science18 399 416 using a solubility profile procedure reported that it was possible to remove diagenetic sr and obtain biologically meaningful sr nevertheless the nelsonet al study is often cited as evidence that a biological signal is irretrievable here infra red spectrometry xrd spectrometry and elemental analyses were used to compare the effects of the nelsonet al protocol with the solubility profile protocol on the crystal structure and crystallinity of the bone and fossil specimens the results show that the procedures used by nelsonet al which include a preliminary ashing step result in severe recrystallization of apatite both before and during the leaching step which deleteriously affects any attempt to recover biological sr by contrast no observable recrystallization takes place in the solubility profile procedure the results imply that the conclusions reached by nelsonet al are primarily artefacts of the specific methods used in their study rather than due to any inherent mechanism of diagenesis

strontium increases and crystallinity changes in taphonomic and archaeological bone bone strontium levels and hydroxyapatite crystal sizes increased with time in two exposed wildebeest skeletons the strontium increases could not be removed by sequential washing according to the method of sillen a 1986 biogenic and diagenetic srca in plio pleistocene fossils of the omo shungura formation paleobiology12 311 323 human subfossil bone recovered archaeologically also showed evidence of extensive diagenetic reworking that resulted in crystal growth and elevated strontium levels the increase in bone strontium content was independent of nonapatitic contaminating crystal phases

effect of the formation of the isthmus of panama on atlantic ocean thermohaline circulation the late cenozoic closure of the seaway between the north andsouth american continents is thought to have caused extensive changes in ocean circulation and northern hemisphere climate1 2 but the timing and consequences of the emergence of the isthmus of panama which closed the seaway remain controversial1 2 3 4 5 here we present stable isotope and carbonate sand fraction records from caribbean sediments which when compared to atlantic and pacific palaeoceanographic records indicate that the closure caused a marked reorganization of ocean circulation starting 4 6 million years ago shallowing of the seaway intensified the gulf stream and introduced warm and saline water masses to high northern latitudes these changes strengthened deep water formation in the labrador sea over the next million years as indicated by an increased deep water ventilation and carbonate preservation in the caribbean sea and favoured early pliocene warming of the northern hemisphere the evaporative cooling of surface waters during north atlantic deep water formation would have introduced moisture to the northern hemisphere although the pronounced intensification of northern hemisphere glaciation between 3 1 and 2 5 million years ago substantially lagged the full development of north atlantic deep water formation we propose that the increased atmospheric moisture content was a necessary precondition for ice sheet growth which was then triggered by the incremental changes in the earth s orbital obliquity

immigrants at the mississippian polity of cahokia strontium isotope evidence for population movement abstract archaeologists have long debated the role of regional interaction in the 11th to 14th centuries at the mississippian polity of cahokia architectural styles exotic materials and cultural objects provide indirect evidence for cultural interaction and ethnic and social diversity however identifying the movement of individuals rather than materials is key to our growing understanding of the population history that enabled the formation of this unique polity this study is the first to use strontium isotope analysis 87sr 86sr of human tooth enamel to identify immigrants at cahokia modern and archaeological fauna were used to establish a baseline local range of strontium isotope ratios for the american bottom region surrounding cahokia teeth from individuals interred in diverse mortuary locations including mounds within this region were analyzed and compared to the local strontium isotope range to identify individuals of non local origin one third of all individuals analyzed were identified as non local and the range and variability of their strontium ratios suggests multiple places of origin the correlation of isotopic data with available biological and mortuary evidence allows us to examine the role of migration in the history of this mississippian polity

87sr 86sr ratios in modern and fossil food webs of the sterkfontein valley implications for early hominid habitat preference this research addresses the potential contribution of strontium isotopes to the reconstruction of early hominid behavior at the swartkrans site in the sterkfontein valley of gauteng provence formally known as the transvaal south africa we report that while there is considerable variability in the 87sr 86sr of whole soils within a 15 km radius of this site available soil and grassland plant 87sr 86sr is much less variable and generally above 0 730 this value is higher more radiogenic than the 87sr 86sr of plants growing within the greenbelt surrounding the blaaubank stream adjacent to swartkrans and streamwater itself 0 721 the difference between grassland and riparian strontium isotope composition suggests a method for determining habitat utilization by early hominids in this study a geological explanation for a natural difference between blaaubank stream and grassland sr is suggested based on relatively less radiogenic sr having lower 87sr 86sr values in the carbonate component of the local dolomite when compared to other nearby geological formations the explanation was tested initially using a top down approach in which the 87sr 86sr ratios of water soil and plants from the entire blaaubank catchment were measured next a bottom up approach was used to examine swartkrans member i faunal species known to have obtained their sr from well defined habitats the results are that 1 pollution is not the explanation for the relatively low 87sr 86sr ratios of the blaaubank stream 2 swartkrans member i carbonate has a similar 87sr 86sr to that of modern blaaubank water indicating that relationships seen today existed in the pleistocene and 3 pleistocene riparian fauna have relatively low 87sr 86sr ratios when compared to fauna adapted to drier habitats together these results make it possible to interpret the strontium isotope composition of pleistocene early hominids from swartkrans in terms of habitat utilization

continental ice in greenland during the eocene and oligocene the eocene and oligocene epochs approximately 55 to 23 million years ago comprise a critical phase in earth history an array of geological records supported by climate modelling indicates a profound shift in global climate during this interval from a state that was largely free of polar ice caps to one in which ice sheets on antarctica approached their modern size however the early glaciation history of the northern hemisphere is a subject of controversy here we report stratigraphically extensive ice rafted debris including macroscopic dropstones in late eocene to early oligocene sediments from the norwegian greenland sea that were deposited between about 38 and 30 million years ago our data indicate sediment rafting by glacial ice rather than sea ice and point to east greenland as the likely source records of this type from one site alone cannot be used to determine the extent of ice involved however our data suggest the existence of at least isolated glaciers on greenland about 20 million years earlier than previously documented at a time when temperatures and atmospheric carbon dioxide concentrations were substantially higher