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

the mid norwegian margin a discussion of crustal lineaments mafic intrusions and remnants of the caledonian root by 3d density modelling and structural interpretation the high density lower crustal body lcb on the mid norwegian margin is almost universally interpreted to represent magmatically underplated material added to the crust during early tertiary opening of the ne atlantic the thickness of the lcb is uneven and its distribution along the margin is sharply limited by margin perpendicular lineaments three dimensional density modelling constrained by petrophysical and seismic data was performed to investigate the expression of the various lineaments bivrost jan mayen gleipne etc in the crustal architecture with and without the lcb the bivrost lineament separating the voring and lofoten margin segments is clearly expressed and so is arguably a lineament in the sw voring margin notably most of the lineaments can be interpreted as offshore prolongations of major onshore detachments stemming from late caledonian orogenic collapse an alternative interpretation of the lcb is thus that it represents high grade metamorphic rocks remnant from the caledonian root determining the nature of the lcb has profound effects for the volume estimate of magmatic rocks in the north atlantic igneous province and consequently also for the degree of crustal thinning and heat flow

iron copper and zinc isotopic fractionation up mammal trophic chains abstract there is a growing body of evidence that some non traditional elements exhibit stable isotope compositions that are distinct in botanical and animal products providing potential new tracers for diet reconstructions here we present data for iron fe copper cu and zinc zn stable isotope compositions in plants and bones of herbivores and carnivores the samples come from trophic chains located in the western cape area and in the kruger national park in south africa the fe cu and zn isotope systematics are similar in both parks however local cu and possibly zn isotopic values of soils influence that of plants and of higher trophic levels between plants and bones of herbivores the zn isotope compositions are 66zn enriched by about 0 8 whereas no significant trophic enrichment is observed for fe and cu between bones of herbivores and bones of carnivores the fe isotope compositions are 56fe depleted by about 0 6 the cu isotope compositions are 65cu enriched by about 1 0 and the zn isotope compositions are slightly 66zn depleted by about 0 2 the isotopic distributions of the metals in the body partly explain the observed trophic isotopic systematics however it is also necessary to invoke differential intestinal metal absorption between herbivores and carnivores to account for the observed results further studies are necessary to fully understand how the fe cu and zn isotope values are regulated within the ecosystem s trophic levels but the data already suggests significant potential as new paleodietary and paleoecological proxies

models of diffusion limited uptake of trace elements in fossils and rates of fossilization abstract many fossils are assumed to take up trace elements by a process of combined diffusion plus adsorption da yet in principle composition profiles can be explained by several different diffusion limited processes including diffusion plus reaction or recrystallization dr and double medium diffusion dmd the da and dmd models are supported by ree and u composition profiles across fossil teeth measured by laser ablation icp ms that show error function like diffusion profiles into enamel from the dentine enamel interface and concentrations in the interior of enamel that are at original biogenic levels or higher published composition and age profiles in some pleistocene bones may be better explained by a dr model all three diffusion models imply linear behavior between age and distance squared vastly simplifying u series dating methods for pleistocene fossils modeled uptake rates for fossil teeth yield a strict minimum bound on durations of about one decade to one century the similarity of diffusion profiles in teeth irrespective of depositional ages ranging from 30 ka to 30 ma implies that uptake occurred quickly with a maximum duration of a few tens of kyr for typical fossil enamel faster uptake is implied for typical fossil bone and dentine disparities in these uptake estimates compared to some archeological bone may reflect sampling and preservation bias for paleontological vs archeological materials

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

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

seismic constraints on a large mafic intrusion with implications for the subsidence history of the danish basin 1 seismic refraction data from the estrid 1 profile are used for seismic velocity modeling along the strike of a large mafic intrusion in the norwegian danish basin central denmark the p wave velocity structure identifies a 8 km thick sedimentary succession with velocities between 1 8 and 5 7 km s the top basement is defined by a step to vp 6 2 km s in the middle to lower crust a high velocity body vp 6 7 km s with its top located at about 10 12 km depth is interpreted as a high velocity and high density gabbroic intrusion of permian age this high velocity body explains the large 50 mgal positive gravity anomaly known as silkeborg gravity high the intrusion has a minimum volume of 40 000 km3 which implies that the magma influx and the consequent cooling of the lithosphere from high temperature could have had profound effects on the subsidence of the danish basin in particular because the magma probably intruded during only a few events and other similar structures cover much of the basin an anomalously high velocity gradient from 7 0 km s in the middle crust to 7 7 km s at 30 32 km depth in the central part of the intrusion coincides with an interval without moho reflections indicative of a gradual transition zone between the crust and the mantle this feature may show the location of the feeder dykes of the intrusion

micro x ray fluorescence μxrf line scanning on cretaceous rudist bivalves a new method for reproducible trace element profiles in bivalve calcite the reconstruction of palaeoclimate on a sub annual scale requires the measurement of chemical proxies in fossil material at a high spatial resolution while various methods for trace element analysis on the micrometre scale are available they are usually destructive to the sample or not widely accessible this study evaluates the performance of a table top micro x ray fluorescence scanner in obtaining reproducible trace element profiles on bivalve calcite standard calibration and repeatability tests demonstrate the robustness of results obtained with this new generation micro x ray fluorescence device that uses a comparatively high excitation energy of 30 w results show that elemental abundances measured using this fast readily accessible and non destructive analytical setup are reproducible on the g g level and therefore suitable for the analysis of the abundance of commonly studied elements in bivalve calcite for example sr mn and fe spectra obtained in this study show considerable improvement in terms of signal to noise ratio compared to earlier table top xrf studies reliability of the measurements is tested using a conservative detection and quantification limit count rates of ca are used to check for point measurements disturbed by irregularities on the sample surface furthermore the method allows semi quantitative two dimensional element mapping which is a convenient tool for the detection of diagenetic alteration in fossil samples the method reveals records of sr ca fe ca and mn ca ratios in a late campanian vaccinites vesiculosus shell with sr ca ratios showing a trend opposite to mn ca and fe ca resulting trace element records are discussed in terms of seasonal cyclicity in the late cretaceous and diagenetic alteration of the fossil shell this article is protected by copyright all rights reserved

high resolution trace element distributions and models of trace element diffusion in enamel of late neolithic early chalcolithic human molars from the rioja alavesa region north central spain help to separate biogenic from diagenetic trends abstract high resolution in situ trace element xrf maps and profiles were measured on the enamel exposed in cross sections through archaeological human permanent molars from seven late neolithic early chalcolithic funerary caves and megalithic graves of north central iberia changes in concentrations of fe zn and sr in inward direction into the enamel shed light on diagenetic and endogenous trace element concentrations in archaeological tooth enamel most of these profiles resemble sigmoid shaped leaching profiles suggesting that a combination of diffusion and advection processes govern the uptake of trace elements into the enamel from pore fluids on the outside of the tooth and in the more porous dentine the present study shows how diffusion advection da models can be fitted to these trace element profiles to explain changes in trace element concentrations that happen during diagenesis da models explain a major part of the variation observed in leaching profiles into the enamel and can be used to reconstruct endogenous trace element concentrations leaching times and leaching depth as well as trace element concentrations in ambient pore water during diagenesis models of trace element leaching together with trace element mapping reveal that fe zn and sr concentrations consistently increase during diagenesis regardless of the type of burial site i e funerary caves vs megalithic graves profiles of pb concentrations show much smaller concentration gradients causing da model fitting to be less accurate modelled leaching depths of 300 400 m warrant a careful approach when sampling for endogenous archaeological tooth enamel for trace element and stable isotope analysis results also show that it is possible to reconstruct endogenous trace element concentrations from these samples even without applying pretreatment procedures because leaching of trace elements into the enamel often remains limited to the outer 300 400 m of the enamel on archaeological timescales modelled leaching times are about ten times lower than the age of the samples suggesting that the rate of trace element leaching into tooth enamel slows down or even halts during the burial period

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

birth of a volcanic margin off argentina south atlantic 1 based on a dense grid of multichannel reflection seismic lines we study the evolution of a volcanic rifted margin segment off argentina the segment under study is located between 44 s and 41 s we describe in detail the facies of the extrusive basaltic complexes across the margin these include single and multiple inner seaward dipping reflectors sdrs with varying architecture along the margin outer highs and outer sdr wedges a detailed interpretation of a transitional zone between the inner and outer sdr wedges is presented multiple inner sdrs are concentrated at the southern part of the margin segment while in the north only one steeply dipping wedge is present the dip of the inner sdr wedges changes along the margin and we propose subsidence by loading as main cause the transitional zone between the inner and outer sdr wedges becomes narrower toward the north by correlating with magnetic data we conclude that the emplacement of the 30 100 km wide multiple inner sdrs occurred episodically we propose an injection center which migrated in a seaward direction with proceeding extension as the origin for the multiple inner sdrs a scissor like opening of the margin segment resulted in different amounts of stretching along strike of the margin segment and is likely the cause for the varying distribution of the extrusive basaltic complexes the varying extension rates within the margin segment contribute to decreasing volumes of melts generated in a northward direction within this rift segment

evolution of the san jorge basin argentina the san jorge basin although small is the most important hydrocarbon producing basin in argentina remaining untested potential is high because of the presence of good source rock favorable structural complexity and multiple reservoirs reservoir quality is commonly low because of the highly tuffaceous sandstones the sedimentary fill of the basin is closely related to its tectonic history northwest southeast trending grabens formed and filled during a triassic and early jurassic early rift phase climaxing with a pervasive middle jurassic volcanic episode continued growth and filling of the basin occurred during a late jurassic earliest cretaceous late rift phase and cretaceous early and late sag phases late cretaceous early tertiary extension set up many of the present day structural traps along normal faults middle tertiary andean compression produced the narrow north south san bernardo structural belt which exhibits reversed movement on older normal graben bounding faults and on local low angle thrust faults marked early to middle tertiary erosion produced a significant unconformi y within cretaceous beds around basin margins origin of upper jurassic and lowermost cretaceous sedimentary fill is primarily lacustrine or fluvial in origin lacustrine organic rich black shales are fringed by oolitic and other limestones and fluvial deltaic sandstones derived mostly from the north a significant southern source of sand existed during the valanginian interbedded marine shales occur mostly to the west toward a presumed marine seaway connection to the northern magallanes basin middle to upper cretaceous sedimentary rocks sourced mostly from the north are mainly fluvial sandstone shale successions with some minor lacustrine influence reservoir quality glauconitic sands were deposited during a late cretaceous early tertiary marine incursion from the atlantic after development of a lower tertiary regional unco formity relatively undisturbed younger tertiary sediments completed the basin fill lower cretaceous lacustrine shales of the d 129 formation are the best source rocks yet identified however most hydrocarbon production occurs above the source in middle and upper cretaceous sandstones along the basin flanks the most obvious hydrocarbon emplacement mechanism is vertical migration along reactivated graben faults

screening in situ bone and teeth preservation by atr ftir mapping abstract bones and teeth are highly hierarchically structured and hererogeneous materials and post mortem processes can reinforce this heterogeneity it is therefore important to consider this heterogeneity to better understand diagenetic processes in this study atr ftir mapping was applied to several heated and un heated archaeological samples and to similar modern references in order to test the potential of this method atr ftir mapping can provide spatially resolved information on alteration state of mineral and organic matter this technique allowed to describe the spatial distribution of organic and mineral matter preservation in unheated palaeolithic bones bize tournal france characterized by a better preservation in the centre of the cortical bone spatial variations in the chemical composition of an archaeological heated bone abri pataud france compared to a modern reference suggested taphonomical uptake of carbonate in the most external part this pattern could correspond to a process of re carbonatation of the calcined mineral matter in the outermost part of the sample due to combustion in a co2 rich atmosphere ftir atr is a powerful tool that allows for identifying and characterizing local heterogeneities in bone preservation this technique open new prospects to reconstruct the taphonomical history of ancient samples

the structure of the dead sea basin abstract the dead sea basin is located along the left lateral transform boundary between the arabian and sinai plates its structure and history are known from surface geology drilling seismic reflection and other geophysical data the basin comprises a large pull apart almost 150 km long and mostly 8 10 km wide which is flanked by a few kilometres wide zones of normal faulting the basin formed at about 15 ma or earlier close to the beginning of the transform motion and it reached about half its present length before the end of the miocene a strong negative gravity anomaly records a thick sediment basin fill 5 km under half its length reaching a maximum of 10 km the fill includes a few km of salt ca 6 4 ma which forms several diapirs at any one time large parts of the basin subsided simultaneously but the site of fastest subsidence seems to have shifted northward sedimentation rates reached at least hundreds of metres per million years or more in the miocene and 1 km myr in later periods the basin structure is dominated by longitudinal faults intrabasinal faults which delimit the pull apart and which are the extensions of the major strike slip faults north and south of the basin and normal faults which extend along the basin margins the latter faults express a small component of extension across the basin whereas the pull apart resulted from the much larger lateral motion along the basin in addition transverse faults divide the pull apart into several segments with somewhat different histories the pull apart grew by becoming longer parallel to the transform motion at shallow levels this was probably achieved by normal slip on transverse listric faults while the fill between them was little deformed the crust under the basin was stretched and thinned during basin lengthening which caused its subsidence basin formation was accompanied by uplifting of its flanks by 1 km sparse igneous activity occurred along the basin and its flanks its presence suggests a thermal anomaly in the lower lithosphere beneath the basin and adjacent parts of the transform

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

basaltic volcanism mantle plumes and the mechanics of rifting the parana flood basalt province of south america dynamic modeling of continental extension between south america and africa shows that the mechanics of rifting played an important role in determining the pattern of volcanism within the parana and etendeka flood basalt provinces on the brazilian and namibian margins the key feature of the model is the development of a horizontal pressure gradient in the lower crust during the early stages of extension which provided a mechanism for transporting magma generated beneath the incipient sea floor spreading axis into the parana province 100 200 km distant the horizontal pressure gradient developed as a consequence of the dynamic interaction of preexisting weaknesses in the middle crust and upper mantle during rifting the model accounts for the large quantity of basalt the asymmetric distribution of basalt on the conjugate margins and the northward migration of the eruptive center with time the rapidity of magma genesis is in agreement with models of decompression melting during rifting the model indicates that although elevated asthenosphere temperatures associated with the tristan plume account for the volume of melt generated the mechanics of rifting control the location and style of emplacement the model suggests that extension in the region began ca 150 155 ma and lasted about 25 m y

introducing a geochemical screen to identify geologically meaningful u pb dates in fossil teeth abstract previous studies have shown that radiometric dating of fossils can be complicated by post fossilisation alteration a key challenge to obtaining geologically meaningful fossilisation dates in bioapatite is identifying regions that have remained relatively undisturbed since the time of fossilisation in order to determine whether a geochemical indicator can be used to identify least disturbed regions we combine in situ trace element analysis and u pb geochronology of fossil teeth from the arroyo chijuillita member new mexico and the dinosaur park formation alberta the reliability of these u pb dates is supported by good agreement between the isotope dilution thermal ionization mass spectrometry 61 5 1 6 ma and laser ablation icp ms 64 2 2 4 ma dates for a targeted tooth region of fourteen teeth analyzed from these units two record dates within uncertainty of the depositional age one has a diffusion concave upward cross sectional yttrium profile the other a concave downward profile reflective of trace element loss it was found for teeth from both units that smaller yttrium concentration ranges are correlated with younger u pb dates likely the result of post fossilisation alteration a yttrium screen based on this relationship is proposed and is found to be a better indicator of post fossilisation open system behaviour in the samples analyzed than other geochemical features thought to be produced during fossilisation this screen provides a new tool for identifying fossil material least disturbed since fossilisation facilitating the use of bioapatite to date the time of diagenesis

differential burning recrystallization and fragmentation of archaeological bone abstract this paper presents research on the conditions under which progressive levels of burning may occur to archaeological bone and how burning damage changes bones crystal structure and susceptibility to fragmentation a k a friability experiments were conducted to simulate common patterns of high temperature bone diagenesis and fragmentation previously documented in paleolithic shelter sites bones buried up to 6 cm below the coal beds of the experimental fires were carbonized but calcination occurred only with direct exposure to live coals analysis by infra red spectroscopy reveals that marked changes in crystallinity accompany the macroscopic transformations in colour and friability of modern fire altered bone specifically a monotonic non linear decrease in mean fragment length across six colour categories was observed when samples were agitated or trampled and a concordant decline in bone identifiability first with respect to skeletal element and ultimately the recognizability of bone tissue itself these findings help qualify the behavioural and taphonomic implications of fragmented burned bones in archaeological sites especially with regard to potential stratigraphic associations between artefacts and hearth features in sites and the intensity of space use by human occupants the identification of burning damage on archaeological bone is a separate issue however it was found that the molecular signatures of recrystallization in modern burned bones partly overlap with recrystallization caused by weathering after only 1 to 2 years of exposure in an arid setting and by partial fossilization of archaeological bones over the long term while infra red and x ray diffraction techniques effectively describe heat induced changes in modern bone mineral and are an important aid for modelling diagenetic processes these techniques did not reliably identify burning damage to archaeological bones cross referencing readily visible colour phases with hcl insoluble fraction data proves much more effective and economically feasible for the latter purpose

evaluating the consequences of diagenesis and fossilization on bioapatite lattice structure and composition abstract changes to hydroxylapatite mineral structure composition and lattice configuration must occur during the transformation of fresh bone to fossil bioapatite mineral phases a paucity of analytical methods to characterize atomic level lattice composition and bonding arrangements in modern and fossil bone has resulted in limited knowledge of how depositional environments and thus diagenetic conditions may influence fossilization processes synchrotron based analyses can provide insight into bone fossilization specifically x ray absorption near edge structure xanes spectroscopy at the p and ca k edges to aid in the interpretation of xanes spectral data from modern bones and from late neogene and late cretaceous fossil bones we applied other established techniques used to characterize bone mineralogy and composition including x ray diffraction fourier transform infrared spectroscopy electron microprobe analysis and thermal analysis specific bone depositional origins and ages likely influenced the varying elemental chemistry preservation of organic matter and mineral content fossilized bones ranging from an almost pure fluorapatite to carbonated fluorapatite mineral phases had less preserved organic material than modern bone the atomic level p and ca lattice structures of fossilized bones differed from modern bones specifically having shifted and shortened ca o bonds due to ca 2 substitution by ionic phases such as iron or rare earth elements and carbonate substitution for phosphate the modified lattice structure regardless of bulk mineral chemistry provides thermodynamic stability in geochemically dynamic depositional environments that may dictate bioapatite preservation over geologic time

late palaeozoic deformation in central africa a result of distant collision seismic reflection profiles from the cuvette centrale central basin of zaire show that a major contractional deformation affected a part of central africa during the late permian and early triassic periods at the same time other regions of central africa experienced extensional and strike slip deformation and associated rift formation the coexistence of such varied styles of tectonic activity over a large continental area resembles the cenozoic tectonics of central asia and northwest europe the intracontinental deformation seen in these latter areas is attributed to collisional processes at a distant continental margin1 3 by analogy we argue here that deformation of central africa in the late palaeozoic period was a direct result of collisional processes some distance away at the southern margin of gondwana

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

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

analogue models of pull apart basins sandbox analogue models of pull apart basins that developed in sedimentary strata above releasing steps in underlying basement faults are characterized by rhombic basins that are flat bottomed box grabens with a subhorizontal synkinematic basin infill steep to nearly vertical sigmoidal oblique slip and segmented oblique extensional faults are the dominant bounding structures of the pull apart basins cross basin short cut faults link the offset principal displacement zones that are characterized by flower structure development the structural architectures of the physical models compare directly in form and dimensions to natural examples of strike slip pull apart basins

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

the lyngen gabbro the lower crust of an ordovician incipient arc we present evidence for the origin of the lyngen gabbro of the ordovician lyngen magmatic complex in troms northern norway the two magmatic suites of the lyngen gabbro strike parallel nne ssw and have distinct magmatic signatures we define these signatures by using major and trace element analyses together with selected major and trace element mineral analyses and 143nd 144nd isotope whole rock analyses of gabbroic to tonalitic plutonic rocks from seven detailed cross sections from this large gabbro complex the western suite of the lyngen gabbro precipitated from magma that may have been derived from the same system as the associated volcanic rocks the gabbros have high an content an 90 of their plagioclases relative to co existing mafic minerals together with somewhat high nd t values 6 this implies that the parental magmas were hydrous tholeiites similar to those found in back arc basins today the eastern suite on the other hand consist of cumulates that were precipitated from melts resembling those of ultra depleted high ca boninitic magmas found in fore arcs extremely high an plagioclases an 95 co exist with evolved mafic minerals and oxides and the nd t values are lower 4 than in the western suite the eastern suite has no volcanic counterpart but dikes intersecting the suites have compositions that possibly represent its parental magma the oceanic rypdalen shear zone generally separates the two suites in the north but several non tectonic transitions from boninitic to tholeiitic signatures southwards advocate that the magmatism happened concurrently the magmatic proximity between the suites the hydrous magmatism and the absence of a silicic or calc alkaline mature arc section suggests that the lyngen gabbro formed in the iapetus ocean under conditions presently found in incipient arcs later emplaced as outer arc highs

preservation assessment of miocene pliocene tooth enamel from tugen hills kenyan rift valley through ftir chemical and stable isotope analyses abstract we investigated fossil tooth enamel of mammals and crocodiles from two mio pliocene east african formations lukeino and mabaget fms using infrared spectroscopy and chemical and stable isotope analyses infrared spectra indicate that the fossil enamel contains biological apatite bioapatite without significant secondary carbonate contaminations several empirical infrared indexes were used to analyze the crystal chemical characteristics of enamel fossil enamel has less organic matter water and structural carbonate of apatite than modern enamel with which it was compared fossil apatite has a better crystallinity than bioapatite the calcium phosphorus mass ratio and the fluorine content of fossil apatite show intermediate values between bioapatite and geological fluorapatite the samples also display significant crystal chemical variations depending on the vertebrate group mammals vs reptiles and the taphonomic context lukeino fm vs mabaget fm in spite of these changes no relationship was observed between the chemical contents carbonate and fluorine and the stable isotope ratios of carbonate 13 c and 18 o in fossil enamel preservation of the palaeoenvironmental signals is strongly supported by the fact that the stable isotope composition of the three investigated fossil mammalian taxa deinotheres equids and hippos is consistent with their ecological features for instance typical c 3 and c 4 plant isotope compositions are reflected in the deinotheres and equids respectively and amphibious hippos display lower 18 o values than terrestrial herbivores as expected

origin and migration of the alpine iceman the alpine iceman provides a unique window into the neolithic copper age of europe we compared the radiogenic strontium and lead and stable oxygen and carbon isotope composition of the iceman s teeth and bones as well as 40ar 39ar mica ages from his intestine to local geology and hydrology and we inferred his habitat and range from childhood to adult life the iceman s origin can be restricted to a few valleys within 60 kilometers south east of the discovery site his migration during adulthood is indicated by contrasting isotopic compositions of enamel bones and intestinal content this demonstrates that the alpine valleys of central europe were permanently inhabited during the terminal neolithic

paleozoic crustal blocks of onshore and offshore central argentina new pieces of the southwestern gondwana collage and their role in the accretion of patagonia and the evolution of mesozoic south atlantic sedimentary basins abstract the southwestern gondwana basement block configuration in the central argentinean offshore area was analyzed using gravimetric magnetic and seismic data and existing onshore tectonic models the resultant maps the distribution of the mesozoic and cenozoic basins and paleozoic structural features were used to validate the interpretations and to produce a new regional tectonic model pre carboniferous southwestern gondwana of south america was interpreted as an open margin formed from east to west by the dom feliciano belt the rio de la plata craton the pampean belt and the pampia and cuyania terranes the collision of the patagonia allochthonous terrane during the late paleozoic resulted in the development of the ventania cape fold belt which was mapped for the first time off the argentinean coast out to 600 km from the shore a strong change in the orientation of the fold belt is referred to as the colorado syntaxis a mirror image of the cape syntaxis in south africa this change reflects the buttressing effect of the cratonic blocks that hamper the northward propagation of syncollisional deformation and resulted in a 180 km shift of the orogenic front the mesozoic basins and the basement block distribution were analyzed the pampean belt a deformed area produced by the pampia accretion to the cratonic area is the locus to two episutural basins the general levalle and macachin basins the salado basin was interpreted as an episutural basin controlled by a 2 1 2 0 ga suture within the rio de la plata craton the colorado basin is composed of four segmented depocenters that reflect different emplacement controls the location of the western colorado basin was controlled by the upper paleozoic orogen the distributions of the central and eastern colorado depocenters orthogonal to the continental boundary were also strongly influenced by the upper paleozoic structures and were offset by lineaments that reflect dom feliciano fabric the colorado basin external depocenter that parallels the continental margin was also controlled by these lineaments we interpret a time gap of some 50 ma between the beginning of the evolution of the margin orthogonal depocenters and the atlantic breakup

tropical seasonality in the late campanian late cretaceous comparison between multiproxy records from three bivalve taxa from oman abstract geochemical proxy records from calcite shells of bivalves constitute an important archive for the reconstruction of palaeoenvironmental conditions on sub annual timescales however the incorporation of these trace element and stable isotope proxies into the shell is influenced by a multitude of physiological and environmental factors that need to be disentangled to enable reliable reconstruction of palaeoclimate and palaeoenvironment in this study records of multiple proxies in three bivalve taxa from the same late campanian locality in oman are used to study the expression of various geochemical proxies in relation to each other and to the palaeoenvironment micro x ray fluorescence mapping allows the localization discussion and evasion of diagenetically altered parts of the fossil shells x ray fluorescence line scanning calibrated with laser ablation inductively coupled plasma mass spectrometry is used to measure trace element profiles through well preserved calcitic parts of the shells records of stable carbon and oxygen isotope ratios of shell calcite are combined with these high resolution trace element concentration profiles to study sub annual variations in shell chemistry and reconstruct changes in the palaeoenvironment of the bivalves on a seasonal scale spectral analysis routines are used to detect cyclicity in stable isotope 18o and 13c and trace element mg ca sr ca s ca and zn ca records differences in seasonal expression between these chemical proxies and between individual shells are discussed in terms of the relative influence of palaeoenvironment and potential species specific physiological effects stable oxygen isotope ratios between shells suggest a local palaeotemperature seasonality of 8 c around an annual mean of 28 c with the shell of the rudistid torreites sanchezi milovanovici yielding slightly higher average temperatures the discussion of the application of various mg ca palaeotemperature calibrations on mg ca records in these bivalve species emphasizes the complexity of using trace element proxies in extinct bivalve species it shows that long term changes in mg ca ratios in ocean water need to be taken into account and that mg ca ratios in bivalves might be influenced by vital effects sr ca and s ca ratios in these fossil taxa are likely controlled by growth and metabolic rates of the shell although an influence of local salinity on strontium to calcium ratios cannot be excluded sub annual variations in zinc concentrations in shell calcite may reflect seasonal variations in palaeoproductivity and redox conditions in the water column

raman spectroscopy of fossil bioapatite a proxy for diagenetic alteration of the oxygen isotope composition abstract fossil bioapatite may yield biogeochemical signals of paleoenvironments captured by living organisms bioapatite may be diagenetically altered however with ions added or removed post mortem such change is typically assessed using destructive and demanding techniques here raman spectroscopy is used as a rapid and non destructive way to identify significant diagenetic alteration of fossil bioapatite we found spectral parameters of phosphate symmetric stretching 1 po43 to be very sensitive to variations in apatite chemistry particularly with respect to common diagenetic components co32 f sr2 the raman spectral parameters were subsequently applied to a set of modern biogenic and geologic magmatic apatite samples as potential endmembers for diagenetic alteration raman spectra were also collected from enamel and dentin respectively resistant vs alteration prone of fossil teeth phosphate oxygen isotopic values from the same enamel dentin samples were used as an index of alteration and provided definition of raman spectral parameters as relates to diagenetic alteration diagenetically altered samples were characterised by spectra with 1 po43 widths at half maximum height less than 13 0 cm 1 and 1 po43 band positions greater than 964 7 cm 1 raman spectroscopy is shown to have potential as a tool for pre screening fossil apatite samples before further analyses

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

subduction mega shear systems and late palaeozoic basin development in the african segment of gondwana basins within the african sector of gondwana contain a late palaeozoic to early mesozoic gondwana sequence unconformably overlying precambrian basement in the interior and mid palaeozoic strata along the palaeo pacific margin small sea board pacific basins form an exception in having a carboniferous to early permian fill overlying devonian metasediments and intrusives the late palaeozoic geographic and tectonic changes in the region followed four well defined consecutive events which can also be traced outside the study area during the late devonian to early carboniferous period up to 330 ma accretion of microplates along the patagonian margin of gondwana resulted in the evolution of the pacific basins thermal uplift of the gondwana crust and extensive erosion causing a break in the stratigraphic record characterised the period between 300 and 330 ma at the end of this period the gondwana ice sheet was well established over the uplands the period 260 300 ma evidenced the release of the gondwana heat and thermal subsidence caused widespread basin formation late carboniferous transpressive strike slip basins e g sierra australes colorado karoo falklands ellsworth central transantarctic mountains in which thick glacial deposits accumulated formed inboard of the palaeo pacific margin in the continental interior the formation of zambesi type rift and extensional strike slip basins were controlled by large mega shear systems whereas rare intracratonic thermal subsidence basins formed locally in the late permian the tectonic regime changed to compressional largely due to northwest directed subduction along the palaeo pacific margin the orogenic cycle between 240 and 260 ma resulted in the formation of the gondwana fold belt and overall north south crustal shortening with strike slip motions and regional uplift within the interior the gondwana fold belt developed along a probable weak crustal zone wedged in between the cratons and an overthickened marginal crustal belt subject to dextral transpressive motions associated with the orogenic cycle was the formation of mega shear systems one of which falklands east africa tethys shear split the supercontinent in the permo triassic into a west and an east gondwana by a slight clockwise rotation of east gondwana a supradetachment basin formed along the tethyan margin and northward displacement of madagascar west falkland and the gondwana fold belt occurred relative to a southward motion of africa

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

what controls thickness of sediments and lithospheric deformation at a pull apart basin we present a simplified three dimensional thermomechanical model of a pull apart basin formed at an overstepping of an active continental transform fault the modeling shows that for a given strike slip displacement and friction on the faults the major parameter that controls basin length thickness of sediments and deformation pattern beneath the basin is the thickness of the brittle layer the unusually large length and sediment thickness of the dead sea basin the classical pull apart basin associated with the dead sea transform can be explained by 100 km of strike slip motion and a thick 20 22 km up to 27 km locally brittle part of the cold lithosphere beneath the basin the thinner sedimentary cover in the gulf of aqaba basin located at the southernmost part of the dead sea transform close to the red sea rift is probably due to a thinner brittle part 15 km of the warmer lithosphere the modeling also suggests no more than 3 km of moho uplift beneath narrow 10 15 km pull apart basins formed in cold lithosphere such as the dead sea basin we also infer that a pull apart basin may only form if a several kilometer thick ductile detachment zone exists between the brittle crust and upper mantle modeling shows that this would not be the case for the dead sea basin if the surface heat flow there were indeed as low as 40 mw m 2 as previously reported we consider this result as an indication that the surface heat flow at the dead sea might have been underestimated

states of preservation of bones from prehistoric sites in the near east a survey abstract a survey of the states of preservation of organic material in 30 fossil bones from 16 different prehistoric sites in the near east shows that whereas almost all the bones have little or no collagen preserved they do with few exceptions contain non collagenous proteins these macromolecules therefore represent an important reservoir of indigenous fossil bone constituents

rolling bones taphonomy of jurassic dinosaur bones inferred from diagenetic microcracks and mineral infillings abstract dinosaur bones from the upper jurassic shishugou formation near qitai in the junggar basin nw china show black manganese oxide and light quartz infillings in the bone pore space such as haversian canals and diagenetic cracks the manganese oxides are identified by x ray diffraction as pyrolusite some haversian canals are only partially filled with pyrolusite which forms miniature geologic spirit levels the orientations of these spirit levels have been measured and several generations of pyrolusite infillings determined indicating that the bones were turned around once or several times during their fossilization characteristic desiccation cracks in the dinosaur bones indicate deposition on the soil surface and early diagenesis under dry climate conditions in the upper jurassic in nw china during dry season evaporation and resulting capillary forces drove the groundwater with dissolved manganese ii ions towards the soil surface and further into the capillary system of the bones hence the capillary system of the bones was already in contact with that of the sediment when the bones were still lying on the surface and were not yet totally embedded in the sediment mn oh 2 precipitated under high ph conditions in the pore space of the bones such as haversian canals and cracks during late diagenesis the mn oh 2 was oxidized to mno2 and transformed into pyrolusite mineral infillings and desiccation cracks in fossil bones thus can yield valuable insights into the taphonomic history of skeletal remains such as environmental conditions during diagenesis and fossil reworking

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

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

mineralogical and compositional changes in bones exposed on soil surfaces in amboseli national park kenya diagenetic mechanisms and the role of sediment pore fluids abstract bones exposed on tropical savannah grasslands of amboseli national park kenya undergo extensive post mortem alteration within 40 years a combined analytical approach involving tem microscopy trace metal analysis ftir spectroscopy and petrographic analysis has revealed a complex dynamic diagenetic environment operating within exposed bones driven by evaporative transport of soil water from the bone soil interface to the upper exposed surface of the bone this process results in extensive bone soil water interaction and is responsible for increases in the concentrations of trace elements such as ba and la of 100 1000 within 15 years the maximum and mean size of bone crystallites increases with continued exposure this change in mean crystallite length is correlated positively with increases in bone crystallinity which in turn is associated with degradation of the bone protein microbial decomposition is rarely observed in the amboseli bones but where present resulted in severe dissolution reprecipitation of bone mineral many bones showed extensive permineralization of the larger vascular spaces with calcite and barite and to a lesser extent crandallite permineralization of unburied bones may account for 95 reduction in macro micron millimeter scale porosity in the bone within 2 years of death we produce a model for pre burial diagenesis of bone in arid tropical environments that highlights extensive alteration of bone chemistry within 1 40 years post mortem

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

colorado basin 3d structure and evolution argentine passive margin abstract this 3d structural model of the colorado basin provides new insights into the crustal geometry of the basin and its evolution in relation with the argentine passive margin three nw se segments oblique to the n30 e trending margin structure the basin the oldest infill is generally thought to be coeval with the rifting of the south atlantic margins in late jurassic early cretaceous this coeval development of the colorado basin and of the passive margin is still under debate and gives rise to several hypotheses that we investigate in the light of our observations we propose that reactivation of inherited structures is predominant in the evolution of the colorado basin 1 the western segment follows the continental continuation of the colorado transfer zone 2 the central segment consists in the continental continuation of the tona deformation zone 3 the eastern segment is superimposed over the palaeozoic claromeco basin in addition to the 3 segments the central high separating the central segment to the eastern segment corresponds to the palaeozoic sierras australes fold belt the direction of extension responsible for the south atlantic opening cannot explain the syn rift infill and thinning of the basin the structural analysis shows two phases of syn rift deformation with different directions thus we suggest that the colorado basin and the south atlantic margin are not coeval but that a first extensional event probably oblique predates the extension responsible for the south atlantic opening this event is then followed by the formation of the n30 trending distal margin and the reactivation of palaeozoic n70 trending faults occurs under the nw se opening of the south atlantic this two phase evolution is consistent with the fault chronology and the two directions of thinned crust observed in the distal margin

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

from bone to ash compositional and structural changes in burned modern and archaeological bone abstract the composition and structure of experimentally heated modern bone and cremated bone fragments from various archaeological sites were analysed by fourier transform infrared spectroscopy ftir in attenuated total reflectance atr mode before and after pre treatment with acetic acid the results confirm that time and temperature have an impact on the degree of calcination but also highlight that once fully calcined the final composition and structure of bone are influenced by temperature alone a combination of several infrared indices makes it possible to discriminate between bones cremated under different conditions the study of archaeological samples revealed that their carbonate composition is quite different to modern calcined bone and that some samples originating from high carbonate geological contexts have significantly higher carbonate concentration compared to modern specimens even after pre treatment the results suggest that ftir yields information on not just the structure of burned bone but also potentially about the modes of burning including cremation and the depositional conditions