a diffusion adsorption model of uranium uptake by archaeological bone abstract an argument for the possibility of uranium uptake by buried bone taking place through the adsorption of uranyl species on bone mineral is advanced in the light of this a diffusion adsorption model for uranium uptake by buried bone is developed the necessary constants are evaluated from the literature and from laboratory measurements of the partition coefficient between solution and bone mineral the geochemical and hydrological parameters which control uptake are discussed the predictions of the model are shown to be in general accordance with the timescale magnitude and distribution of uranium uptake in archaeological bone using the model specific predictions of the variation of apparent uranium series ages in bone can be made and bone is shown clearly not to conform to the closed system assumption when the model is extended to tooth enamel it is found to be incompatible with the early uptake model used for esr dating but to fall between the early uptake and linear uptake models similarly it suggests that uranium series dates on enamel assuming a closed system are liable to underestimate the true age by at least one third

high resolution u series dates from the sima de los huesos hominids yields 600 66 kyrs implications for the evolution of the early neanderthal lineage the sima de los huesos site of the atapuerca complex near burgos spain contains the skeletal remains of at least 28 individuals in a mudbreccia underlying an accumulation of the middle pleistocene cave bear ursus deningeri we report here on new high precision dates on the recently discovered speleothem sra 3 overlaying human bones within the sima de los huesos earlier analyses of this speleothem by tims thermal ionization mass spectrometry showed the lower part to be indistinguishable from internal isotopic equilibrium at the precision of the tims instrumentation used yielding minimum age of 350 kyr kyr 103 yr before present reanalysis of six samples of sra 3 by inductivelycoupled plasma multicollector mass spectrometry icp ms produced high precision analytical results allowing calculation of finite dates the new dates cluster around 600 kyr a conservative conclusion takes the lower error limit ages as the minimum age of the speleothem or 530 kyr this places the sh hominids at the very beginnings of the neandertal evolutionary lineage

early diagenesis and recrystallization of bone abstract one of the most challenging problems in paleobiology is determining how bone transforms from a living tissue into a fossil the geologic record is replete with vertebrate fossils preserved from a range of depositional environments including wetland systems however thermodynamic models suggest that bone modeled as hydroxylapatite is generally unstable in a range of varying geochemical conditions and should readily dissolve if it does not alter to a more thermodynamically stable phase such as a fluorine enriched apatite here we assess diagenesis of alligator bone from fleshed articulated skeletons buried in wetland soils and from de fleshed bones in experimental mesocosms with and without microbial colonization when microbial colonization of bone was inhibited bioapatite recrystallization to a more stable apatite phase occurred after one month of burial ca fe phosphate phases in bone developed after several months to years due to ion substitutions from the protonation of the hydroxyl ion these rapid changes demonstrate a continuum of structural and bonding transformations to bone that have not been observed previously when bones were directly in contact with sediment and microbial cells rapid bioerosion and compositional alteration occurred after one week but slowed after one month because biofilms reduced exposed surfaces and subsequent bioapatite lattice substitutions microbial contributions are likely essential in forming stable apatite phases during early diagenesis and for enabling bone preservation and fossilization

early diagenesis of bone and tooth apatite in fluvial and marine settings constraints from combined oxygen isotope nitrogen and ree analysis abstract fossil bones and teeth of late pleistocene terrestrial mammals from rhine river gravels rs and the north sea ns that have been exposed to chemically and isotopically distinct diagenetic fluids fresh water versus seawater were investigated to study the effects of early diagenesis on biogenic apatite changes in phosphate oxygen isotopic composition 18opo4 nitrogen content wt n and rare earth element ree concentrations were measured along profiles within bones that have not been completely fossilized and in skeletal tissues bone dentine enamel with different susceptibilities to diagenetic alteration early diagenetic changes of elemental and isotopic compositions of apatite in fossil bone are related to the loss of the stabilizing collagen matrix the ree concentration is negatively correlated with the nitrogen content and therefore the amount of collagen provides a sensitive proxy for early diagenetic alteration ree patterns of rs and ns bones indicate initial fossilization in a fresh water fluid with similar ree compositions bones from both settings have nearly collagen free ree u f and sr enriched altered outer rims while the collagen bearing bone compacta in the central part often display early diagenetic pyrite void fillings however ns bones exposed to holocene seawater have outer rim 18opo4 values that are 1 1 to 2 6 higher compared to the central part of the same bones 18opo4 18 2 0 9 n 19 surprisingly even the collagen rich bone compacta with low ree contents and apatite crystallinity seems altered as ns tooth enamel 18opo4 15 0 0 3 n 4 has about 3 lower 18opo4 values values that are also similar to those of enamel from rs teeth therefore ree concentration n content and apatite crystallinity are in this case only poor proxies for the alteration of 18opo4 values seawater exposure of a few years up to 8 kyr can change the 18opo4 values of the bone apatite by 3 therefore bones fossilized in marine settings must be treated with caution for palaeoclimatic reconstructions however enamel seems to preserve pristine 18opo4 values on this time scale using species specific calibrations for modern mammals a mean 18oh2o value can be reconstructed for late pleistocene mammalian drinking water of around 9 2 0 5 which is similar to that of late pleistocene groundwater from central europe

identifying the reworking and stratigraphic provenance of bones by exploring multivariate geochemical relationships with the perio spot technique abstract erosional processes often rework materials of different ages into the same sedimentary facies producing time averaged deposits such reworking is common at archaeological sites and researchers must consider the resulting time averaging effects when using natural stratigraphy to situate artifacts and remains in time at scladina cave a neandertal site in belgium we developed a method for identifying reworked facies and the stratigraphic provenance of mammal bones based on their post mortem trace element characteristics and crystallinity we collected sixty two faunal remains from throughout the site s sedimentary sequence and analyzed them for trace element concentrations and crystallinity with laser ablation inductively coupled plasma mass spectrometry and raman spectroscopy our novel approach the perio spot technique quantifies the trace element characteristics and crystallinity from the most diagenetically altered part of a bone with high spatial resolution trace element concentrations rare earth element patterns and crystallinity of perio spots correlate throughout the scladina sedimentary sequence based on stratigraphic trends in bone chemistry and crystallinity we subdivide the scladina sequence into two successive periods of early diagenesis a period of later diagenesis and a transitional period between the early and later diagenesis periods the period boundaries also correspond to major climatic fluctuations identified in the site s stratigraphy by other means e g palynology and heavy mineralogy the stratigraphic provenance of nine cave bear femora support the confinement of reworking to within each of the diagenetic periods the provenance of two indeterminate faunal remains that visually resemble the taphonomic alteration of the scladina neandertal taphonomic proxies suggest that the individual may be significantly older than previously hypothesized evaluating the temporal integrity of exhumed assemblages and the original sedimentary context of bones with our method is thus a valuable addition to archaeological analyses especially beyond the temporal range of radiocarbon dating or in contexts with very low preservation potential of organic materials

glacier meltwater and runoff modelling keqicar baqi glacier southwestern tien shan china meltwater and runoff from keqicar baqi glacier a large glacier in the southwestern tien shan northwestern china are simulated using a modified degree day model including potential clear sky direct solar radiation coupled with a linear reservoir model for the period 1 july to 12 september 2003 there is good agreement between modelled and measured meltwater at ablation stakes and between simulated and observed runoff at the glacier terminus a reconstruction of glacier meltwater and runoff from an assumed debris free surface during the study period shows that the effect of the debris layer on glacier meltwater generation crucially affects glacier runoff the model is also used to calculate glacier runoff given the climate scenario resulting from a doubling of co2 as projected by the recm2 regional climate model the projected changes in temperature and precipitation vary from 0 to 2 78c and from 0 to 25 respectively results indicate that glacier runoff increases linearly with temperature over these ranges whether or not the debris layer is taken into consideration the effect of change in temperature is much more noticeable than that for change in precipitation due to the debris layer predominantly covering and insulating the ablation area the response of glacier runoff is less sensitive to temperature increase with a debris covered surface than with a debris free surface glacier runoff is also markedly reduced when a reduced glacier area is prescribed in the 2 78c scenario

thermal maturity of carbonaceous material in conodonts and the color alteration index independently identifying maximum temperature with raman spectroscopy abstract the color alteration index cai of conodont specimens is commonly used for identifying the maximum temperature to which units of sedimentary rock particularly carbonates have been heated observable color variations in these fossils are thought to be a result of the thermally induced structural evolution of organic carbonaceous matter cm such temperature history information is extremely valuable for applications in hydrocarbon exploration as well as for constraining other temperature related geological processes in sedimentary systems however the identification of cai depends on the qualitative visual assessment of color which along with a host of other potential complications may yield inaccurate determinations of maximum temperature raman spectroscopy allows thermally induced structural changes in cm to be quantified and it has been used to estimate the thermal maturity in metasedimentary rocks for almost two decades here we use raman spectroscopy of carbonaceous material rscm in conodont specimens and their mississippian to upper triassic host rocks from british columbia canada to estimate maximum temperatures based on the transformation structural reorganization of disordered carbon to graphite this study demonstrates that the maximum temperatures experienced by conodont specimens as calculated from rscm using the iterative fitting of raman spectra ifors technique correlate well with cai but lie outside the suggested ranges in some instances this may be due to complex thermal histories of these conodont specimens or the influence of diagenetic alteration not thermal histories on conodont color we recommend the application of raman spectroscopic analyses of cm in conodonts and their host rocks to obtain more confident accurate and precise estimations of maximum temperature that are independent of cai

a simple model to estimate ice ablation under a thick debris layer this paper presents a simple model to estimate ice ablation under a thick supraglacial debris cover the key method employed in the model is to establish a link between the debris heat flux and the debris temperature at a certain depth when the heat transfer in the debris is described by a diffusion process given surface temperature debris thermal properties and relevant boundary conditions the proposed model can estimate mean debris temperature at interfaces of different debris layers using an iterative procedure and then the heat flux for ice ablation the advantage of the proposed model is that it only requires a few parameters to conduct the modeling which is simpler and more applicable than others the case study on koxkar glacier west tien shan china shows in general that the proposed model gives good results for the prediction of debris temperatures except for an apparent phase shift between modeled and observed values we suggest that this error is mainly due to complex phase relations between debris temperature and debris heat flux the modeled ablation rates at three experimental sites also show good results using a direct comparison with observed data and an indirect comparison with a commonly used energy balance model

rare earth elements ree and yttrium in stream waters stream sediments and fe mn oxyhydroxides fractionation speciation and controls over ree y patterns in the surface environment we have collected 500 stream waters and associated bed load sediments over an 400 km 2 region of eastern canada and analyzed these samples for fe mn and the rare earth elements ree y in addition to analyzing the stream sediments by total digestion multi acid dissolution with metaborate fusion we also leached the sediments with 0 25 m hydroxylamine hydrochloride in 0 05 m hcl to determine the ree y associated with amorphous fe and mn oxyhydroxide phases we are thus able to partition the ree into dissolved 0 45 lm labile hydroxylamine and detrital sediment fractions to investigate ree fractionation and in particular with respect to the development of ce and eu anomalies in oxygenated surface environments surface waters are typically lree depleted la sm nasc ranges from 0 16 to 5 84 average 0 604 n 410 where the ree are normalized to the north america shale composite have strongly negative ce anomalies ce ce nasc ranges from 0 02 to 1 25 average 0 277 n 354 and commonly have positive eu anomalies eu eu nasc ranges from 0 295 to 1 77 average 0 764 n 84 in contrast the total sediment have flatter ree y patterns relative to nasc la sm nasc ranges from 0 352 to 1 12 average 0 778 n 451 and are slightly middle ree enriched gd yb nasc ranges from 0 55 to 3 75 average 1 42 most total sediments have negative ce and eu anomalies ce ce nasc ranges from 0 097 to 2 12 average 0 799 and eu eu nasc ranges from 0 39 to 1 43 average 0 802 the partial extraction sediments are commonly less lree depleted than the total sediments la sm nasc ranges from 0 24 to 3 31 average 0 901 n 4537 more mree enriched gd yb nasc ranges from 0 765 to 6 28 average 1 97 and ce and eu anomalies negative and positive are more pronounced the partial extraction recovered on average 20 of the fe in the total sediment 80 of the mn and 21 29 of the rees ce 19 and y 32 comparison between rees in water partial extraction and total sediment analyses indicates that rees y in the stream sediments have two primary sources the host lithologies i e mechanical dispersion and hydromorphically transported the labile fraction furthermore eu appears to be more mobile than the other ree whereas ce is preferentially removed from solution and accumulates in the stream sediments in a less labile form than the other rees y despite poor statistical correlations between the rees y and mn in either the total sediment or partial extractions based on apparent distribution coefficients and the ph of the stream waters we suggest that either sediment organic matter and or possibly d mno2 feooh are likely the predominant sinks for ce and to a lesser extent the other ree in the stream sediments

reconstructing depositional histories through bone taphonomy extending the potential of faunal data reconstructing the sequences of deposition of archaeological material is central to the interpretation of archaeological sites and provides the foundations for how site chronology is understood generally stratigraphy provides the most direct evidence for understanding depositional histories however in certain instances stratigraphic relationships may be obscured or unobservable and therefore other sources of evidence must be drawn upon for defining deposits and reconstructing sequences of deposition this is a particular problem at dark earth sites which are homogeneous in terms of the colour and texture of deposits and also in artefact rich samples which have little sedimentary matrix this paper explores the potential of a new approach to the analysis of bone taphonomic data for the purposes of deciphering depositional histories when stratigraphy is unobservable integral to this method is rigorous statistical analysis of modification data combined with an assessment of the taxonomic and anatomical composition of deposits in terms of their susceptibility to modification this facilitates more confident interpretation of modification patterns as deposit composition can be discounted from responsibility for significant differences the approach is tested on a sample area of the later prehistoric midden of potterne wiltshire uk through detailed recording and statistical analysis of bone modifications weathering gnawing and trampling this research demonstrates that bone taphonomy is not only useful for identifying distinct depositional events in apparently homogeneous strata but can also provide detail on the nature of processes responsible for the formation of the deposit

a critical re evaluation of the miocene pliocene boundary as defined in the mediterranean abstract a critical re evaluation of the miocene pliocene m p boundary as defined informally in the mediterranean is presented we show that ages reported earlier for this boundary ranging from 4 81 to 4 93 ma do not imply any diachroneity of the basal zanclean lithohorizon which reflects the pliocene flooding of the mediterranean and defines the m p boundary these ages most likely represent an artefact resulting from intraformational variations in sedimentation rate and inconsistent interpretation of coluor variations in terms of sedimentary cycles the best estimate for the age of this boundary arrives at 4 86 ma if the conventional geomagnetic polarity time scale gpts of berggren et al 1 is used and at 5 16 ma if the new gpts of cande and kent 2 is used an age of 5 32 ma is obtained if the astronomically calibrated time scale of hilgen 3 is adhered to because of its presumably global paleoclimatological significance the m p boundary as currently defined in the mediterranean is preferred to a redefinition of this boundary at the gilbert chron 5 boundary in a continous open marine sequence outside the mediterranean in addition this redefinition would lead to unnecessary confusion in global chronostratigraphy

rare earth element systematics of fossil bone revealed by la icpms analysis intra bone rare earth element ree fractionation trends were studied by la icpms analysis to put constraints on 1 the mechanisms controlling ree fractionation within fossil bones 2 the relative timing of ree uptake in various parts of fossil bone and 3 the origin of ree in fossil bones we have evaluated ree bone profiles across 54 fossil bones from a broad range of well characterised taphonomic settings ranging in age from triassic to early medieval ree patterns and concentration gradients are highly variable and intra bone fractionation trends in la yb n vs la sm n space of few specimens cover almost the entire range previously observed for bulk samples intra bone variability of ce anomalies as well as variable y ho and la la n is also observed sometimes diagenetic fluids with fractionated hree enriched compositions have entered the bone from the marrow cavity producing secondary ree uptake profiles theoretical intra bone fractionation trends modelled using lattice strain theory concur with most ree data but some trends cannot be modelled using realistic boundary conditions this fact as well as the occurence of positive and negative ce anomalies within the same fossil sample hint towards changing ree compositions of diagenetic fluids over the timescales of ree uptake because apparent ce anomalies frequently evolve over bone profiles and ce anomalies can be inherited from previous fractionation events ce anomalies are a highly ambiguous tracer for constraining ambient redox conditions in general bioapatite ree signatures may not always reliably reflect ambient taphonomic or redox conditions and diagenetic fluid compositions therefore ree patterns and ce anomalies of fossil bones must be interpreted cautiously as they vary spatially within skeletal remains and are affected by intra bone fractionation processes as well as changing compositions of the diagenetic fluid

high resolution records of location and stratigraphic provenance from the rare earth element composition of fossil bones abstract bone apatite acts as a natural timed sampling device scavenging trace elements from local pore waters over timescales of ca 1 50 ka the rare earth element ree and u th composition of fossil bones reflects associated pore water compositions during the period of recrystallisation the ree composition of fossil bones is controlled by partitioning of ree between pore waters and particle surfaces and the ree composition of fossil bones reflects the ree composition of pore waters which vary spatially and temporally light ree are preferentially sorped onto particle surfaces thus the high la yb values seen in many bones from coastal marine and aeolian environments are best explained by release of ree from light ree enriched particles to local pore waters and subsequent immobilisation in recrystallising bones the ree compositions of bones recovered from pedogenically altered diatomite sediments of the olorgesailie formation of southern kenya vary over spatial scales of less than 10 m location accounts for 48 of the observed variation in bone chemistry and bones recovered from eight discrete excavations within the same time equivalent stratigraphic layer can be assigned to their excavation location with 70 accuracy based on a discriminant analysis of ree u and th composition despite this within layer variation bones recovered from different stratigraphic horizons within the olorgesailie formation can also be distinguished on the basis of their trace element composition bones recovered from four stratigraphic horizons spanning ca 0 5 million years were assigned to their correct stratigraphic layer with 90 accuracy where sedimentological conditions are favourable the trace element composition of fossil bone may be used to test stratigraphic provenance and burial location in excavated bone with a temporal resolution of

solubilities of bone mineral from archaeological sites the recrystallization window abstract bone mineral solubility is an important parameter for understanding the preservation of bones in the archaeological and palaeontological records in this study we have measured the solubility of the carbonated hydroxyl apatite of sub recent and fossil bones as well as synthetic hydroxyl apatite in deionized water and in ph buffered solutions the solutions were open to the atmosphere and the ph values were around neutral measurement conditions that are relevant to bone mineral preservation in nature but that were absent from most previous studies we obtained internally consistent results from both the water and the buffered experiments supporting the notion that we are measuring an inherent property of the mineral phase we found that bone mineral is much more soluble than synthetic hydroxyl apatite we measured the ionic activity products at steady state conditions and we identify a recrystallization window between ph 7 6 and 8 1 which defines the conditions under which bone crystals dissolve and reprecipitate as a more insoluble form of carbonated hydroxyl apatite as these conditions are common in nature most fossil bones will not maintain their original crystals with time we also found that bones that contained small amounts of calcite did not dissolve at all during our experiments these results provide a basis for better understanding the conditions in sediments under which bones are preserved and the relative states of preservation of bone they also have important implications for the selection of the most appropriate bone samples for paleoenvironmental and paleodiet analyses and dating

patterns of chemical change during bone fossilization the uptake of elements by bone during fossilization is a well recognized phenomenon but the nature of and the factors leading to chemical heterogeneity in fossil bone are only just starting to be elucidated indeed in the recent past the assumption that fossil bone is chemically homogeneous has been commonly used in several investigations including those of bone dating and dietary studies in an attempt to understand the processes of element uptake we have investigated some chemical heterogeneities in a fossil bone and have assessed the potential use of bone composition as an indicator of the trace element contents of associated groundwater our study extends other work1 2 by giving the first analysis of rare earth element ree distribution in a fossil bone and by showing that information on the redox state and ree abundance pattern of the groundwater can be obtained the results contribute to the interpretation of bone analyses in studies on provenance and age determination as well as in the diet and health of past populations

reconstructing taphonomic histories using histological analysis abstract recent years have seen rapid advances in the understanding of diagenetic changes to bone tissues and how these influence the chemistry microstructure and histological appearance of ancient bone it is now possible to recognise many characteristic features of diagenetically modified bone and this has led to the potential use of these parameters in estimating the potential survival of biogenic signals such as dna lipids proteins and stable isotopes these characteristic features also hold the potential for preserving a record of different post mortem environments in individual bones or assemblages of bones from the same site in sites where the burial conditions have changed over archaeological or geological timescales histological analyses can shed light on these different burial environments and permit the reconstruction of taphonomic histories of some bones examination of polished sections of bone using bse sem has been used to identify characteristic features attributed to aerobic soil bacteria cyanobacteria and sulphate reducing bacteria the approach shows promise for providing supplementary evidence when phasing complex sites such as graveyards which developed over several hundred years

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

a new cambrian black pigment used during the late middle palaeolithic discovered at scladina cave andenne belgium abstract sedimentary unit 1a at scladina cave belgium has yielded archaeological material from a middle palaeolithic occupation dating to between 40 210 400 350 bp and 37 300 370 320 bp fifty one fragments of a black friable rock with a black streak were found in association with 194 burned bone fragments and several thousand lithic artefacts this black material is interpreted as a pigment brought to the site by neandertals the pigment was analysed by petrography xrd raman microspectroscopy and other geochemical methods it was identified as a highly siliceous graphitic siltstone this is a very unique discovery as european archaeological research has so far only recorded black pigments comprised of manganese oxides from the middle palaeolithic raman microspectroscopy is a non destructive method able to distinguish the attributes of black siliceous materials that originate from different tectono sedimentary contexts by measuring the degree of alteration of the carbonaceous material this method allowed for the determination of its geographical and geological origins a cambrian formation of very limited extent located near ottignies about 40 kilometres north west of scladina cave the absence of a drainage network connecting the two locations eliminates the possibility of natural transport and supports its anthropogenic origin

from bone to fossil a review of the diagenesis of bioapatite the preservation of bone or bioapatite over geologic time has presented paleobiologists with longstanding and formidable questions namely to elucidate the mechanisms processes rates and depositional conditions responsible for the formation of a fossil from a once living tissue approaches integrating geochemistry mineralogy physics hydrology sedimentology and taphonomy have all furthered insights into fossilization but several fundamental gaps still remain notably our limited understanding of 1 the timing of processes during diagenesis e g early and or late 2 the rate of bioapatite transformation into thermodynamically more stable phases 3 the controls imparted by depositional environment and 4 the role of micro biology in determining the fate of bone bioapatite dissolution or preservation the versatility of fossil bioapatite to provide information on the biology of extinct vertebrates rests on our ability to identify and characterize the changes that occurred to bioapatite during diagenesis this review will evaluate our current understanding of bioapatite diagenesis and fossilization focusing on the biogeochemical transformations that occur during diagenesis to the mineral and organic components of bone excluding teeth and enamel the analytical approaches applied to evaluate fossilization processes and outline some suggestions for future promising directions

diagenesis of bones from eland s bay cave abstract archaeological bone specimens have been shown in a number of studies to have increased mineral crystallinity when measured both by xrd and ir spectrometry in this study we investigated the relative dating potential of ir crystallinity measurements based on the splitting factor or sf on a sample of 54 specimens from the holocene sequence at eland s bay cave south africa in addition to sf c and n measurements were obtained using a carlo erba elemental analyser results of the study indicate that i a reasonably good correlation between sf and time exists in bones under 20 000 years bp but that the increase in sf levels off after this period and ii correlations between diagenetic indicators such as sf c and n are better than those between any indicator and time an excellent correlation r2 0 81 was obtained between sf residing in the inorganic phase and n residing in the organic phase suggesting that diagenesis of the two phases of bone are linked implications of the data for monitoring stratigraphic anomalies at archaeological sites are discussed

distribution of debris thickness and its effect on ice melt at hailuogou glacier southeastern tibetan plateau using in situ surveys and aster imagery debris cover is widely present in glacier ablation areas of the tibetan plateau and its spatial distribution greatly affects glacier melt rates high resolution in situ measurements of debris thickness on hailuogou glacier mount gongga southeastern tibetan plateau show pronounced inhomogeneous debris distribution an analysis of transverse and longitudinal profiles indicates that the ground surveyed debris thicknesses and advanced spaceborne thermal emission and reflection radiometer aster derived thermal resistances of debris layers correlate strongly over the entire ablation area across and along glacier patterns of aster derived thermal resistance correspond well with spatial patterns of debris thickness which may reflect large scale variations in the extent and thickness of the debris cover the ice melt rate variability over the ablation area simulated by a surface energy balance model that considered thermal resistance of the debris layer indicates clearly the crucial role of debris and its spatial continuity in modifying the spatial characteristics of melt rates because of the inhomogeneous distribution of debris thickness about 67 of the ablation area on hailuogou glacier has undergone accelerated melting whereas about 19 of the ablation area has experienced inhibited melting and the sub debris melt rate equals the bare ice melt rate in only 14 of the ablation area

visualizing fossilization using laser ablation inductively coupled plasma mass spectrometry maps of trace elements in late cretaceous bones elemental maps generated by laser ablation inductively coupled plasma mass spectrometry la icp ms provide a previously unavailable high resolution visualization of the complex physicochemical conditions operating within individual bones during the early stages of diagenesis and fossilization a selection of la icp ms maps of bones collected from the late cretaceous of montana united states and madagascar graphically illustrate diverse paths to recrystallization and reveal unique insights into geochemical aspects of taphonomic history some bones show distinct gradients in concentrations of rare earth elements and uranium with highest concentrations at external bone margins others exhibit more intricate patterns of trace element uptake related to bone histology and its control on the flow paths of pore waters patterns of element uptake as revealed by la icp ms maps can be used to guide sampling strategies and call into question previous studies that hinge upon localized bulk samples of fossilized bone tissue la icp ms maps also allow for comparison of recrystallization rates among fossil bones and afford a novel approach to identifying bones or regions of bones potentially suitable for extracting intact biogeochemical signals

why do crystallinity values fail to predict the extent of diagenetic alteration of bone mineral spectroscopic indicators of bone crystallinity such as the infrared splitting factor irsf are commonly used to determine the general state of preservation of ancient bone in principle such indices might be expected to act as a proxy for alteration of bone mineral and thus could be used to screen bones or portions of bones for likely preservation of in vivo biogenic trace element and stable isotope signals we tested the relationship between irsf and bone mineral composition in two suites of well characterised recent and pleistocene bones initially crystallinity change and trace element uptake are correlated apparently both controlled by decomposition of the organic phase and exposure of bone crystal surfaces this relationship breaks down in older bones where authigenic phosphate growth and mineral pore water interactions are no longer rate limited by the breakdown of collagen and exposure of crystal surfaces in these conditions the extent of chemical alteration of bone will be controlled by site specific conditions and thus while ftir spectra of bone provide a broad indication of organic content and apatite recrystallisation they are not reliable proxies for the degree of diagenetic alteration in terms of biogenic geochemical signals

identifying the geochemical taphonomy of the osteological material from katsambas rockshelter we report analytical work undertaken in order to identify the geochemical taphonomy of the osteological collection human and animal bones recovered from a 1950s excavation at katsambas a small cavity in the marly limestone on the west bank of kairatos river crete the site had funerary use and yielded material of neolithic and minoan age with poor stratigraphical association disintegration of provenance labels from bags has introduced further uncertainty about the contexts of recovery samples of human and animal bones that macroscopically appear to belong to three taphonomic categories were studied by means of ft ir spectroscopy tem microscopy and ree analysis to explore the taphonomical processes the bones have undergone although not novel in palaeontological research the use of ree opens a new path to investigating poorly provenanced osteological collections from old excavations such geochemical work offers a proxy to their relative dating through the evaluation of the time span bones have remained in the sediments and their respective taphonomic histories

deciphering bone depositional sequences in caves through the study of manganese coatings the presence of black coloured bones in caves has been sometimes associated to the use of fire by humans but more frequently the agent responsible for black colour is the natural deposition of manganese oxides manganese coatings were not usually studied once human action was discarded however they can provide valuable information about the origin and the sequence of formation of a palaeontological or archaeological deposit in this paper we present a quantitative and qualitative study of the manganese coatings that affect most of the bones recovered in the palaeontological site of linares cave nw of iberian peninsula together with other taphonomic marks the manganese coatings are superimposed on other features previously existing on the surface of the bones in turn the coatings can be affected by other agents that modified them totally or partially the combined interpretation of the different taphonomic marks provides us with valuable information on the sequence where the different taphonomic processes were produced as for example the intervention of carnivores in the disarticulation of some elements before the burial the preservation of anatomic connections until after the burial of the carcasses and the existence of reworking processes in some parts of the infill

evaluating the impact of acetic acid chemical pre treatment on old and cremated bone with the perio spot technique and perios endos profiles abstract the impacts of diagenesis on archaeological and palaeontological bone complicate investigations of in vivo chemical and isotopic characteristics such bone is often pre treated in an attempt to remove diagenetic alteration prior to trace element or isotopic analyses although very few standardized approaches exist for evaluating pre treatment effectiveness in this pilot study we characterize the diagenetic alteration and assess the impact of acetic acid chemical pre treatment on the trace element and structural characteristics of four bones from belgium including an early medieval cremated bone from broechem and three representative old bones of different ages ca 40 130 ka from the late pleistocene sedimentary sequence of scladina cave each bone was analyzed before and after acetic acid pre treatment using the perio spot technique and perios endos profiles we measured trace element concentrations with laser ablation inductively coupled plasma mass spectrometry la icp ms and micro x ray fluorescence spectroscopy xrf structural characteristics were investigated with raman spectroscopy and fourier transform infrared spectroscopy ftir our results indicate that chemical pre treatment had little to no significant impact on the trace element content of the early medieval cremated bone had the most impact on the youngest bone from scladina cave and had less impact on the trace element content of two older bones from scladina cave this suggests that the effectiveness of acetic acid chemical pre treatment is greater for bones undergoing early diagenetic processes has minimal impact on highly crystalline cremated bone and may preferentially leach in vivo signatures from bones undergoing later diagenesis the weights of leachates removed from each bone also correspond well with their hypothetical diagenetic states indicating that researchers could potentially assess the diagenetic state of bones by weighing the leachates produced during acetic acid pre treatment therefore our new approach may provide a valuable step toward effectively and consistently differentiating among in and ex vivo trace element signatures and by proxy those of their isotopes in archaeological and palaeontological bone

timescales and mechanisms of ree and hf uptake in fossil bones abstract rare earth element ree patterns of fossil bones and teeth are widely used as proxies for provenance taphonomy and palaeoenvironment in order to investigate if fossil bones behave as closed systems over geologic time ree profiles were analysed by la icpms along cross sections of 54 bones from various well characterised and well dated settings these include terrestrial and marine diagenetic environments covering early triassic to holocene ages in general all fossil bones exhibit the highest ree concentrations at the outer rim gradually decreasing by up to four orders of magnitude toward the inner bone cortex intra bone ree concentration gradients decrease significantly from quaternary via tertiary to mesozoic specimens suggesting long term ree uptake and open system behaviour of fossil bone this view is further corroborated by 176lu 176hf dating of selected samples all yielding significantly younger ages than the known chronostratigraphic ages hence there is clear evidence for long term open system behaviour of fossil bones with respect to ree which is in marked contrast to currently accepted models suggesting that ree uptake is only early diagenetic although unexpected statistically significant four to seven point isochrons are observed for four fossil dinosaur bone samples and one upper triassic mastodonsaurus tooth with mswds ranging from 0 083 to 4 5 notably mobility of lu alone cannot account for the observed age patterns assuming constant lu uptake rates over time the radiometric ages should only be as low as half of the chronostratigraphic age however a six point isochron defined by subsamples of a single upper triassic mastodonsaurus tooth yields an age of 65 2 1 1 ma mswd 0 68 much younger than half of the stratigraphic age ca 234 ma hence hf must also undergo late diagenetic exchange likely mechanisms to account for the presence of statistically meaningful isochrons as well as for the late diagenetic exchange of both ree and hf are diffusion adsorption and dissolution reprecipitation processes