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

merging spatial and spectral datasets to place olivine in stratigraphic context at arruntia crater a rare window into vesta s northern hemispheric crust abstract a major goal of the dawn mission to vesta was to test and refine current models of the asteroid s formation by characterizing the distribution of mineral components on its surface detection of the mineral olivine by the visible and infrared mapping spectrometer vir and the framing camera fc onboard dawn was a key milestone in this effort and was expected to help resolve a debate regarding the dominant mode of vesta s petrologic evolution i e magma ocean vs serial magmatism however the subtleties of the olivine spectral signature combined with the small size of individual olivine rich exposures tens of meters prohibits detailed mapping of this petrologically significant mineral component when the data from either instrument are evaluated independently as a result the particular role of these olivine exposures in vesta s geologic history remains largely unresolved here we fully characterize the type locality of vesta s olivine rich materials the northern hemisphere craters bellicia and arruntia using a novel data fusion approach for linking the vir and fc datasets specifically we have leveraged a spectral mixture analysis framework to create a new dataset that maps or extrapolates full resolution spectra derived from vir data onto the higher spatial resolution of fc when used as an exploratory tool in conjunction with the original fc and vir data the new extrapolated dataset reveals important new details about the distribution of olivine around bellicia and arruntia craters there are clear compositional distinctions between the exposures at the two craters with a much stronger olivine component in the walls of bellicia than arruntia the proximal arruntia ejecta appear more consistent with high proportions of an evolved high calcium pyroxene as in eucrites than with an enhanced olivine component examples of diogenite rich howardite also occur in the region further we leverage arruntia s role as the freshest large crater in the northern hemisphere and thus a rare window into the vesta s northern hemispheric crust to suggest an overall stratigraphy for the region a thin veneer of howardite overlies a sequence of diogenite rich near surface olivine rich intermediate and eucrite rich materials at depth the manner of exposure of these various components in a marked stratification point to a plutonic model for emplacing these mineralogically unique components in the near surface of vesta

re dating changyang cave in hubei province southern china abstract owing to the unearthed left maxillary fragment and left lower premolar fossil in 1950s changyang cave was regarded as an important hominin site where middle pleistocene hominins are first discovered in southern china however only two bovine tooth fossils have been dated to 194 24 20 ka and 196 20 17 ka by u series dating since 1980s in this work the stratigraphy of changyang cave was re investigated by applying u th dating method for eight new tooth fossils obtained from fossil layer and two carbonate crystal samples from clay cement on the wall of this cave new dating results showed that the ages of the two carbonate crystals are 256 and 233 ka respectively and those of the eight tooth fossils are concentrated from 193 ka to 143 ka considering the ages of the two previous fossils new carbonate crystals and new eight tooth fossils we suggested that the age range of changyang hominin is between 196 and 143 ka

the origin of vesta s crust insights from spectroscopy of the vestoids high quality vnir spectra of 15 vestoids small asteroids that are believed to originate from vesta were collected and compared to laboratory spectra and compositional data for selected hed meteorites a combination of spectral parameters such as band centers and factors derived from modified gaussian model fits band centers band strengths calculation of the low to high ca pyroxene ratio were used to establish if each vestoid appeared most like eucrite or diogenite material or a mixture of the two howardite this resulted in the identification of the first asteroid with a ferroan diogenite composition 2511 patterson this asteroid can be used to constrain the size of diogenite magma chambers within the crust of vesta the vestoids indicate that both large scale homogeneous units 5 km and smaller scale heterogeneity 1 km exist on the surface of vesta as both monomineralogic eucrite or diogenite material alone and mixed both eucrite and diogenite spectra are observed the small scale of the variation observed within the vestoid population is predicted by the partial melting model which has multiple intrusions penetrating into the crust of vesta it is much more difficult to reconcile the observations here with the magma ocean model which would predict much more homogeneous layers on a large scale both at the surface and with depth

thermal modelling of the melut basin sudan and south sudan implications for hydrocarbon generation and migration abstract the thermal history of the melut rift basin was studied in a number of wells and along a northeast southwest cross sectionacross the basin using 1 d and 2 d basin models modelling was conducted using petromod software to test subsidence thermal history and their implications for hydrocarbon generation migration and accumulations geotherms were found ranging between 24 and 44 c km and average 32 c km and present day heat flow was found to vary between 53 and 65 averaging 59 mw m 2 a geologicaly realistic paleoheat flow model with higher heat flow peaks of 75 70 and 65 mw m 2 during the first second and third rifting phases respectively calibrated against vitrinite reflectance data was employed the model was found sensitive to cenozoic erosions and a 600 m of exhumation did support the vitrinite data in providing a reasonable fit in most locations using the easy ro vitrinite kinetic model for maturity the average present day oil window was found between 1565 and 4050 m in the wells studied and between 1705 and 4200 m along the cross section using type ii kerogen for the aptian albian source rocks the hydrocarbon generation and expulsion were modelled and revealed that the generation started as early as 95 ma in some areas but significant generation rates were during the second rifting phase and expulsion started at around 85 ma calculations of the probable expelled amounts of hydrocarbon from the northern sub basin are high and up to 2 2 10 11 bbls of oil and 2 3 10 14 ft 3 of gas migration of oils from cretaceous source rocks kitchen to the cenozoic traps was probably through faults porous carrier beds and breaching of traps cap rocks the filling of these traps might be periodic during the rifting episodes and hydrocarbons remigrated from deeper traps to shallow ones it is possible that thinner and siltier cap rocks along the hydrocarbon migration path may have allowed gas to scape but holded the oil back it is most probable that part of the hydrocarbons might have been generated from shallower source rocks areas and a 2 d hybrid darcy flow path model have demonstrated this and predicted a number of accumulations which are similar to the known large discoveries such as palogue fal and adar yale oil fields

u pb dating of a speleothem of quaternary age we demonstrate that u pb dating is a promising method for secondary carbonate materials of quaternary age and older by obtaining a 206pb 238u age for a speleothem with high u 10 g g 1 and very low pb 10 ng g 1 that is supported by an independent 230th age thermal ionisation mass spectrometry was used to determine the u and pb isotopic ratios and concentrations for subsamples of a stalactite from winnats head cave peak district uk we obtained 206pb 204pb ratios up to 50 and determined a 206pb 238u age of 248 10 ka which is within error of the 207pb 235u age of 333 79 ka and a spectrometric u th age of 255 ka for samples of tertiary and quaternary age the initial state of u series disequilibrium is an important consideration and as with most radiometric dating techniques the mineral must have remained closed to u th pb and all intermediate daughters we show that dense calcite speleothems are ideal in this respect and that no loss of rn has occurred unlike u series disequilibrium methods u pb dating has no upper limit and hence materials of quaternary age older than 0 6 ma can be analysed to investigate landscape development paleoclimate hominid evolution or hydrogeochemistry in carbonate terrains

reflectance spectra of the elephant moraine a79001 meteorite implications for remote sensing of planetary bodies abstract eeta 79001 a shergottite meteorite includes a pair of nonbrecciated basaltic lithologies joined along a planar igneous contact these two lithologies a and b are examples of the type of basaltic contacts likely to occur on the surfaces of many planetary bodies as such eeta 79001 offers a unique opportunity to compare analysis techniques available in situ with those available remotely for comparison to petrologic and geochemical studies reflectance spectra of lithologies a and b are obtained and analyzed with the modified gaussian model mgm this modeling leads to the unambiguous identification of two pyroxene phases in each lithology all spectral features including an absorption near 1 2 m often attributed to plagioclase are found to be due solely to the presence of two pyroxenes this ambiguity between pyroxene and plagioclase absorptions suggest that caution be used in interpretation of remote spectra results from the mgm analysis of spectra of eeta 79001 are also used to provide estimates on the major element composition of the pyroxene phases in the two lithologies in addition based solely on spectral analyses lithology b is shown to have 11 17 more high calcium pyroxene relative to low calcium pyroxene than lithology a each of the results derived independently with the mgm are shown to compare favorably within 5 10 to those obtained from more traditional geochemical and petrographic methods the compositional inferences that were derived from modeling the spectra of eeta 79001 with the mgm are examples of the type of information available from remotely acquired spectral data by providing a method for determining changes in relative composition and abundance of pyroxenes in neighboring units the mgm offers an opportunity to add compositional information to geologic and morphologic data and thus greatly enhance the science return on studies of surfaces throughout the solar system

unequilibrated eucrites and the equilibrated juvinas eucrite pyroxene ree systematics and major minor and trace element zoning in unequilibrated eucrites pyroxene is a sensitive recorder of variables that affect their crystallization histories therefore major minor and trace element systematics of pyroxene were evaluated from several unequilibrated eucrites and an equilibrated eucrite juvinas by emp and sims techniques the cr ai and ti zoning trends in pyroxene reflect its igneous crystallization history including the sequence of crystallization of pyroxene and plagioclase the primary substitutional couples in unequilibrated pyroxene among cr ai and ti are 6jcr3 14iap 16iap 14jap and 16jti4 2 4jap with the 16jti4 2 4jap couple dominating over 16jap 14jap following the onset of plagioclase crystallization reequilibration erases the primary igneous zoning trends of cr ai and ti and the dominant substitutional couples in homogenized pyroxene are 16iti4 214jap and 16jcr3 14jap in equal proportions trace element compositions in unequilibrated eucrites are variable because of igneous zoning but averaged analyses show core rim differences that reflect their ca rich rims relative to ca poor cores the pyroxene ree abundances in the unequilibrated samples are as much as ten times chondrite in their rims whereas homogenized juvinas pyroxenes have abundances between the core and rim values of pyroxene from unequilibrated eucrites the ratio of rees homogenized pyroxenelbulk composition for juvinas is significantly higher than the ratio of rees pyroxene coreslbulk composition for the unequilibrated eucrites this is especially true for the hrees the higher observed ree concentrations in the equilibrated pyroxene result from the intracrystalline exchange between ca poor cores and ca rich rims and also from intercrystalline exchange with other phases including plagioclase phosphates and mesostasis use of the equilibrated pyroxene ree concentrations and igneous d values leads to an incorrect estimate of the parental melt composition the estimated chondrite normalized melt ree concentrations are too high by a factor of two to four these studies suggest that great care must be used to take into account subsolidus elemental redistributions when attempting to estimate parental melt compositions from measured mineral trace element concentrations

petrologic insights from the spectra of the unbrecciated eucrites implications for vesta and basaltic asteroids we investigate the relationship between the petrology and visible near infrared spectra of the unbrecciated eucrites and synthetic pyroxene plagioclase mixtures to determine how spectra obtained by the dawn mission could distinguish between several models that have been suggested for the petrogenesis of vesta s crust e g partial melting and magma ocean here we study the spectra of petrologically characterized unbrecciated eucrites to establish spectral observables which can be used to yield mineral abundances and compositions consistent with petrologic observations no information about plagioclase could be extracted from the eucrite spectra in contrast pyroxene dominates the spectra of the eucrites and absorption band modeling provides a good estimate of the relative proportions of low and high ca pyroxene present cr is a compatible element in eucrite pyroxene and is enriched in samples from primitive melts an absorption at 0 6 lm resulting from cr 3 in the pyroxene structure can be used to distinguish these primitive eucrites the spectral differences present among the eucrites may allow dawn to distinguish between the two main competing models proposed for the petrogenesis of vesta magma ocean and partial melting these models predict different crustal structures and scales of heterogeneity which can be observed spectrally the formation of eucrite allan hills alh a81001 which is primitive cr rich and relatively unmetamorphosed is hard to explain in the magma ocean model it could only have been formed as a quench crust if the magma ocean model is correct then alha81001 like material should be abundant on the surface of vesta and the vestoids

olivine rich exposures at bellicia and arruntia craters on 4 vesta from dawn fc we present an analysis of olivine rich exposures at bellicia and arruntia craters using dawn framing camera fc color data our results confirm the existence of olivine rich materials at these localities as described by ammannito et al 2013a using visual infrared spectrometer vir data analyzing laboratory spectra of various howardite eucrite diogenite meteorites high ca pyroxenes olivines and olivine orthopyroxene mixtures we derive three fc spectral band parameters that are indicators of olivine rich materials combining the three band parameters allows us for the first time to reliably identify sites showing modal olivine contents 40 the olivine rich exposures at bellicia and arruntia are mapped using higher spatial resolution fc data the exposures are located on the slopes of outer inner crater walls on the floor of arruntia in the ejecta as well as in nearby fresh small impact craters the spatial extent of the exposures ranges from a few hundred meters to few kilometers the olivine rich exposures are in accordance with both the magma ocean and the serial magmatism model e g righter and drake 1997 yamaguchi et al 1997 however it remains unsolved why the olivine rich materials are mainly concentrated in the northern hemisphere approximately 36 42 n 46 74 e and are almost absent in the rheasilvia basin

bone and enamel diagenesis from the crystal to the environment a tribute to jean francois saliege a universite de lyon france cnrs france ecole normale superieure de lyon site monod 15 parvis rene descartes bp7000 lyon f 69342 france universite claude bernard lyon 1 43 bd du 11 novembre 1918 f 69622 villeurbanne cedex france b museum national d histoire naturelle cnrs departement ecologie et gestion de la biodiversite usm 303 umr 7209 du cnrs archeozoologie archeobotanique societes pratiques et environnements case postale 56 55 rue buffon f 75231 paris cedex 05 france

discovery of a basaltic asteroid in the outer main belt visible and near infrared spectroscopic observations of the asteroid 1459 magnya indicate that it has a basaltic surface magnya is at 3 15 astronomical units au from the sun and has no known dynamical link to any family to any nearby large asteroid or to asteroid 4 vesta at 2 36 au which is the only other known large basaltic asteroid we show that the region of the belt around magnya is densely filled by mean motion resonances generating slow orbital diffusion processes and providing a potential mechanism for removing other basaltic fragments that may have been created on the same parent body as magnya magnya may represent a rare surviving fragment from a larger differentiated planetesimal that was disrupted long ago

uranium series dating of fossil coral reefs extending the sea level record beyond the last glacial cycle abstract absolutely dated records of past sea level change are extremely important for understanding the advance and retreat of the large ice sheets when combined with other complementary climate archives and climate models such records offer the potential to gain an improved understanding of earth s natural climate cycles providing a firmer basis for assessing the role of anthropogenic effects such as greenhouse gas emissions in modifying climate the u series dating of fossil coral reefs has been widely utilized to provide absolutely dated records of past sea level change and numerous observations now exist for the past 130 000 years spanning the last glacial cycle despite this controversies still exist regarding the exact timing and character of sea level events within this time interval and extending the sea level history further back in time on the basis of robust and independent age constraints for older fossil reefs remains very elusive this is primarily due to a progressive loss in the resolution of the u series chronometer as one goes further back in time coupled to a lack of well preserved dateable coral in older fossil reefs to overcome these limitations the primary challenges are three fold first new analytical protocols are required to improve the resolution of the u series chronometer enhanced analytical precision must be coupled to accuracy through continued refinement of the u series decay constant determinations and via the implementation of rigorous inter laboratory calibration exercises second efforts should continue to be focussed on gaining an improved understanding of the mechanisms controlling open system exchange of the u series isotopes in fossil reef systems this will allow the number of reliable u series observations to be extended third alternative dateable archives of past sea level change must continue to be emphasized to further complement the coral reef database these limitations are discussed in the context of current developments that further advance the application of u series chronology to older fossil reef systems formed prior to the last glacial cycle

surface lithologic heterogeneity of asteroid 4 vesta abstract high precision spectrophotometry of 4 vesta the third largest asteroid was used to establish the surface composition of this body and to investigate mineralogical variations across its surface the average surface of vesta is analogous to howardite and or polymict eucrite assemblages regolith derived members of the hed meteorite suite which consist of a eucrite matrix containing differing amounts of a diogenite component color and or spectral changes which exhibit a consistent relationship to rotational phasing are evident in 16 of 18 studies of vesta dating back to 1929 including the present work after elimination of possible sources of spurious spectral or color changes it is concluded that these variations arise from hemispheric variations in surface materials and hence provide a means of spatially resolving subhemispheric compositional units on the surface of vesta the background surface of vesta is a relatively dark howardite or polymict eucrite pyroxene plagioclase assemblage with several compositionally distinct bright regions clustered in one hemisphere viewed around the maximum in vesta s lightcurve these include what appears to be an olivine bearing unit suggested name leslie formation located near vesta s equator which probably represents an impact basin and or its associated ejecta that penetrated through the basaltic crust other high albedo compositional units including an apparently low calcium eucrite region and several diogenite pyroxenite regions at least one located near the southern pole may be smaller shallower impact basins by analogy to the eucrite meteorites which represent surface flows or shallow intrusions and which constitute the major component of the regolith derived howardites and polymict eucrites we conclude that the howardite polymict eucrite units represent a regolith gardened original surface of vesta it is probable that the low albedo of the background surface on vesta is due to an age related darkening effect similar to that inferred from the galileo images of gaspra and ida this mechanism is consistent with the correlation of absorption feature intensity with the lightcurve vesta appears to have an old eucritic surface darkened with age and represented among the meteorites by the regolith derived howardites and polymict eucrites on which several impacts on one hemisphere have exposed fresher brighter diogenite and olivine bearing material based on qualitative analysis of the mineralogical variations as a function of rotation a generalized lithologic map of vesta was produced there is reasonable control on the longitude of lithologic features but little control on their latitudes except where specifically noted in producing this map discrete circular features were used on the plausible assumption that impacts have been the most important geologic process on this surface for most of the age of the solar system the shape of the features has thus been assumed rather than derived and is subject to future revision as data improve

u series dating of bone using the diffusion adsorption model abstract u series dating of bone has suffered problems of reliability since its inception because bone remains an open system with respect to uranium commonly applied a priori assumptions of u uptake such as early uptake or linear uptake are inadequate because they have no physical or chemical bases no means of demonstrating which model is suitable for a particular bone and no intrinsic tests of reliability despite this and numerous examples of anomalous u series dates such assumptions are still routinely applied we address this problem using the diffusion adsorption d a model of u uptake millard and hedges 1996 which incorporates a physicochemical description of u uptake using this model we show how the u uptake of a bone responds to geochemical changes in the burial environment which can lead to phenomena such as the removal of u from bones leaching or u uptake late in their burial history recent uptake and we show how the overall uptake history is reflected in distributions profiles of u and u series isotopes across a bone section we present measurements of u concentration profiles and 230 th 234 u profiles on archeological bone from a number of different sites and burial environments and compare the results to profiles predicted by the d a model bones that have undergone complex uptake histories which include u leaching or recent uptake are identified on the basis of these profiles and rejected as unsuitable for dating for bones that appear to have undergone uptake under constant geochemical conditions the d a model is applied to calculate u series dates with much improved reliability

mineralogy of asteroid 1459 magnya and implications for its origin detailed near infrared spectral observations of asteroid 1459 magnya reveal an asteroid that is primarily composed of pyroxene and plagioclase feldspar confirming earlier suggestions that magnya has a basaltic composition the average magnya spectrum for march 23 2002 has a band i center of 0 926 m and a band ii center of 1 938 m observations over 4 1 hours show little variation in band center positions the feldspar to pyroxene ratio is 0 6 on magnya s surface comparing magnya with the spectral parameters from 4 vesta shows discordant pyroxene chemistries magnya s pyroxenes contain 10 mol less fs than vesta s pyroxenes this suggests that magnya originated from a parent body other than 4 vesta and that its progenitor formed in a more chemically reduced region of the solar nebula within the asteroid belt

laser ablation u series analysis of fossil bones and teeth abstract over the past decade we have applied laser ablation icp mass spectrometry u series analysis to a large number of bones and teeth the method is fast and provides high resolution data of u series isotopes which give insights into the complexity of uranium migration into within and out of bones in this paper we present our laser ablation approach in detail from the experimental set up to data reduction and uranium diffusion modelling laser ablation analysis can now be applied with minimum damage complete diffusion data sets can be obtained by laser drilling which leaves a hole of around 200 m in diameter and 1 2 mm depth if the natural u diffusion follows a simple single stage process valuable age information can be obtained in other cases highly complex u migrations have been observed which make any age assessment impossible two examples from wadjak and callao illustrate the potential of nearly non destructive laser ablation u series analysis of human skeletal tissues the results demonstrate the physical presence of modern humans in south east asia at a time when our species just started to migrate into europe

uranium series age estimates for rock art in southwest china we report the first uranium series age estimates for rock art in china calcite bracketing a paint layer was used to constrain the age of a naturalistic outline hunter gatherer painting in the jinsha river area of northwest yunnan province southwest china the rock paintings in this region are unique in style and content compared with other bodies of rock art in china which are dominated by neolithic subject matter the minimum and maximum ages were determined using isochron techniques on multiple samples of calcite from above and beneath the paint layer a large painted deer head was dated to between 5738 and 2050 years this painting and underlying flowstone are superimposed on older paintings that suggest the older paintings are at least 3400 years old if not older than 5738 years the results indicate for the first time that jinsha river rock art is older than other forms of rock art in the region and show that rock art likely extends back to at least the transition from the palaeolithic to neolithic in this part of china

hominid cave at thomas quarry i casablanca morocco recent findings and their context the thomas quarry i locality was made famous in 1969 with the discovery of a human half mandible in a cave in 1985 further investigations revealed the presence of a lower acheulean assemblage in lower units of the section from 1988 onwards modern controlled excavations took place within the framework of the franco moroccan co operative project casablanca acheulean artefacts a rich mammalian fauna and four hominid teeth have been excavated from the cave the faunal set indicates an open woodland environment carcasses were processed by carnivores but cut marks are absent which raises the question of any human role in the bone accumulations stone knapping was mainly oriented towards flake production and a few bifaces have been imported into the site laser ablation icp ms dating combining the esr and u series data for the modelling of the u uptake has given an us esr age of 501 76 ka for a human premolar while new osl measurements yielded an age of 420 34 ka for sediments immediately above the dated tooth and 391 32 ka below nevertheless biostratigraphy and lithostratigraphy point towards a greater antiquity

pyroxene spectroscopy revisited spectral compositional correlations and relationship to geothermometry the authors wish to thank the various agencies which have provided the necessary support for this project including grants in aid of research from sigma xi the scientific research society to e a c the geological society of america grant 3741 87 to e a c and nasa planetary geology and geophysics grant nagw 642 to m j g

the genesis of diogenites and hed parent body petrogenesis abstract samples of clasts and whole rocks from eighteen of the twenty four known diogenites orthopyroxenite breccia meteorites have been studied by combined inaa empa in order to elucidate their petrogenetic history the incompatible elements a12o3 and tio2 are positively correlated in diogenite orthopyroxenes these elements determined by empa are also positively correlated with incompatible trace elements such as yb determined by inaa on bulk samples these correlations indicate that most diogenites may form a single igneous fractionation sequence the incompatible minor and trace elements are decoupled from the major elements for essentially constant mg tio2 varies by about 4 times and yb by about 8 times hence there is no strong evidence for igneous fractionation preserved in the major element composition of orthopyroxenes geothermometry calculations using two pyroxene and spinelorthopyroxene thermometers show that these phases in diogenites maintained equilibrium to temperatures in the range 650 880 c far below likely magmatic temperatures in some diogenites orthopyroxenes of differing composition are in breccia contact therefore the low equilibration temperatures were achieved in the diogenites prior to brecciation decoupling of major and trace elements was most likely caused by slow subsolidus cooling in the diogenite pluton which allowed ca fe and mg to reach diffusive equilibration incompatible trace elements likely have much lower diffusivities in orthopyroxene and therefore may have largely preserved their magmatic distributions the extensive variation in incompatible trace elements indicates that either the diogenites were formed through an extensive crystallization interval or that partition coefficients greatly increased during crystallization if the former were true one would expect to find substantial amounts of plagioclase in the diogenites if they are comagmatic with eucrites this is contrary to observations a model in which diogenites crystallized from one or more melts of approximately orthopyroxenitic composition can satisfy both the mineralogie and trace element constraints

exploring exogenic sources for the olivine on asteroid 4 vesta abstract the detection of olivine on vesta is interesting because it may provide critical insights into planetary differentiation early in our solar system s history ground based and hubble space telescope hst observations of asteroid 4 vesta have suggested the presence of olivine on the surface these observations were reinforced by the discovery of olivine rich hed meteorites from vesta in recent years however analysis of data from nasa s dawn spacecraft has shown that this olivine bearing unit is actually impact melt in the ejecta of oppia crater the lack of widespread mantle olivine exposed during the formation of the 19 km deep rheasilvia basin on vesta s south pole further complicated this picture ammannito et al ammannito e et al 2013a nature 504 122 125 reported the discovery of local scale olivine rich units in the form of excavated material from the mantle using the visible and infrared spectrometer vir on dawn these sites are concentrated in the walls and ejecta of craters arruntia 10 5 km in diameter and bellicia 41 7 km in diameter located in the northern hemisphere 350 430 km from rheasilvia basin s rim here we explore alternative sources for the olivine in the northern hemisphere of vesta by reanalyzing the data from the vir instrument using laboratory spectral measurements of meteorites our rationale for using the published dataset was to bypass calibration issues and ensure a consistent dataset between the two studies our analysis of the vir data shows that while the interpretation of their spectra as an olivine rich unit is correct the nature and origin of that olivine could be more complicated we suggest that these olivine exposures could also be explained by the delivery of olivine rich exogenic material this hypothesis is supported by meteoritical evidence in the form of exogenic xenoliths containing significant amount of olivine in some of the hed meteorites from vesta previous laboratory work on heds show that potential sources of olivine on vesta could be different types of olivine rich meteorites either primitive achondrites acapulcoites lodranites ureilites ordinary chondrites h l ll pallasites or carbonaceous chondrites e g cv based on our spectral band parameters analysis the lack of correlation between the location of these olivine rich terrains and possible mantle excavating events and supported by observations of hed meteorites we propose that a probable source for the olivine seen in the northern hemisphere corresponds to remnants of impactors made of olivine rich meteorites the best curve matching results with laboratory spectra suggest these units are hed material mixed with either ordinary chondrites or with some olivine dominated meteorites such as r chondrites

non destructive gamma spectrometric u series dating prehistoric hominid fossils are too valuable to be dated by destructive or even partially destructive methods non destructive u series dating by ray counting can therefore be a valuable method if relatively large hominid fragments such as skulls containing measurable amounts of uranium are available we present a description of the method as well as some results including those obtained from a previously dated coral as well as two australian hominid skulls wlh 50 and mungo 3 the dating procedure is designed to minimise systematic errors which may easily overwhelm statistical errors if care is not taken the gamma spectrometric results are in good agreement with alpha and mass spectrometric measurements as well as independent age determinations the results show no evidence for any uranium uptake over longer time periods

reflectance spectroscopy of plagioclase dominated mineral mixtures implications for characterizing lunar anorthosites remotely anorthositic rocks dominate the moon s upper crust as remnants of the lunar magma ocean lmo small variations in the mineralogy of these rocks may hold key information about the homogeneity of lmo composition and solidification processes orbital near infrared nir sensors are sensitive to mineralogy but technologic advances have only recently enabled detection of the plagioclase component in crustal rocks based on an absorption band centered near 1250 nm anorthosites occupy a unique mineralogic range that is well suited for nir studies the highly transparent component plagioclase is present in high abundances while the spectrally dominant mafic or oxide minerals are present in only minor abundance as a result spectra of anorthosites are more likely than many other rock types to contain visually discernable signatures from more than one mineral component facilitating their identification and characterization in nir data in support of new nir measurements for the moon we present laboratory spectral analyses of well controlled plagioclase dominated mineral mixtures we focus on the spectral effects of varying mafic and oxide composition and abundance in mixtures with a common plagioclase end member the results demonstrate that plagioclase can be a significant contributor to reflectance spectra when strongly absorbing minerals are present in low abundance we show that the contribution of plagioclase is more pronounced in mixtures with pyroxenes and certain spinels but more easily masked in mixtures containing small amounts of olivine differences in minor mineral composition are clearly expressed in bulk spectra modeling of mixtures using a hapke nonlinear approach accurately estimates mineral abundances in laboratory spectra to within 5 vol for mixtures with 90 vol plagioclase together these results imply that not only should orbital nir data sets be able to discern the presence of plagioclase in anorthositic crustal exposures but also that detailed information about anorthosite mineral assemblages can be reliably accessed in reflectance spectra

further studies for uranium series dating of fossil bone abstract in an earlier paper the authors suggested that bones from well sealed depositional matrices might be deteable by the u series method this paper presents the results of further case studies on bones from archaeological sites and also in vitro laboratory studies of the u bone system these suggest that the u series method may only be of limited use for bones and that in most sites samples are exposed to an unknown number of wetting events over their period of deposition the laboratory experiments indicate a more complex process than the simple diffusion of u through the bone cross section

near infrared reflectance spectra from bulk samples of the two martian meteorites zagami and nakhla abstract zagami and nakhla are achondrites and belong to the shergotty nakhla chassigny snc meteorite group it is generally accepted that mars is their parent body mineralogical and chemical analyses have revealed that the major mineral phases of these two meteorites are pyroxene olivine maskelynite and plagioclase in this work near infrared biconical reflectance measurements were performed on sawed surfaces of chips from zagami and nakhla spectra obtained with an analytical spot diameter on the order of the mineral grain size reflect the heterogeneous distribution of different mineral phases the characteristic absorption bands of the pyroxenes are numerically evaluated in terms of the modified gaussian model spectra with overlapping absorption features are resolved into the basic absorption bands from these results it can be estimated what kind of clinopyroxenes belong to the investigated mineral assemblages as a result the major clinopyroxene phase in nakhla is ca rich augite whereas in zagami both ca rich and ca poor pyroxenes are present by means of such a procedure laboratory spectra of minerals become more informative and may help in discussing martian remote sensing data in the near infrared region

petrology of the unbrecciated eucrites abstract twenty nine unbrecciated eucrites have been thoroughly characterized in terms of the petrologic factors that affect their spectra such as mineral chemistry modal adundances grain sizes and textures we have conducted a combined petrologic and spectral study designed to provide insight into the petrogenesis of the basaltic crust of vesta and the variety of rock types that exist within it as well as aid in the petrologic interpretation of spectra to be collected by the dawn orbiting spacecraft this paper details the petrology part of the study unbrecciated eucrite samples were selected to avoid the complications of lithologic mixing in the accompanying spectral study a wide variety of textural types are seen within the basaltic eucrites encompassing quenched coarse grained and granoblastic samples zoned pyroxenes in eucrites and those that preserve a history of initial rapid cooling are rare nearly all eucrite samples have been thermally metamorphosed and would commonly be classified as equilibrated however this term reflects only the quadrilateral mg fe and ca compositions of pyroxenes and considerable variations are seen within the minor elements al ti and cr in pyroxenes as well as plagioclase compositions determination of both pyroxene and plagioclase compositions together with pyroxene geothermometry provides a better estimate for the relative degree of thermal metamorphism a eucrite has experienced the petrologic differences observed here might allow different eucrites to be distinguished spectrally this is especially true for the varying pyroxene compositions as the spectra of eucrites are dominated by absorption features attributed to pyroxene

morphology and evolution of drowned carbonate terraces during the last two interglacial cycles off hilo ne hawaii abstract the eastern side of hawaii island is a rapidly subsiding margin dominated by drowned carbonate platforms we present detailed bathymetric and backscatter data remotely operated vehicle and submersible observations sedimentological and 14c accelerator mass spectrometry and u th age data from seven submerged terraces h7 h2a d h1a b in water depths between 1100 and 25 m off hilo north eastern hawaii the main carbonate deposits on these terraces are coral deposits rhodolith beds coralline algal mounds crusts pavements and tabular sheets we identified five previously described sedimentary shallow to deep water facies and one new facies type that are consistent with reef drowning on a rapidly subsiding margin we used palaeobathymetric data derived from the sedimentary facies age versus depth relationships and published sea level curves to estimate a uniform long term subsidence rate of 2 80 0 36 m ky for the eastern side of hawaii over the last 150 ky terrace h7 developed about 380 ka based on data from the western side of the island active coral growth on terrace h2d occurred during the marine isotope stage mis 6 to 5 transition and the terrace drowned during the peak of mis 5e when sea level rose faster than reefs could grow favoured by the gentle platform gradient reefs established progressively landwards with a backstepping pattern during mis 5e to form the terraces h2c and h2b 122 ka final turn off of shallow water carbonate production on terraces h2b d coincided with the relative sea level rise of the interstadial mis 5a bathymetry and submersible data suggest that carbonate sediments on terraces h2a and h1b were deposited over an antecedent topography of local lava deltas emplaced during rising sea levels at ca 85 and 65 ka while terrace h1a established on lava delta substrates of the mauna loa volcano ca 11 ka we conclude that the initiation growth and drowning of coral reef terraces off hilo differ in some ways from the pattern observed in the submerged terraces in the western side of hawaii and that the platform evolution off hilo is more strongly influenced by emplacement of offshore lava flows

characterization of the 1 2 μm m1 pyroxene band extracting cooling history from near ir spectra of pyroxenes and pyroxene dominated rocks the 1 2 m band in near infrared spectra of pyroxenes results from fe2 in the m1 crystallographic site the distribution of fe and mg between the m1 and m2 sites is in part a function of the cooling rate and thermal history of a pyroxene combining near infrared and mssbauer spectra for a series of compositionally controlled synthetic mg fe ca pyroxenes we quantify the strength of the 1 2 m band as a function of fe2 in the m1 site near infrared spectra are deconvolved into component absorptions that can be assigned to the m1 and m2 sites using the modified gaussian model the relative strength of the 1 2 m band is shown to be directly related to the amount of fe2 in the m1 site measured by mossbauer spectroscopy the strength of the 1 2 m band relative to the combined strengths of the 1 2 and 2 m bands or the m1 intensity ratio is calculated for 51 howardite eucrite and diogenite hed meteorites diogenites and cumulate eucrites exhibit the lowest m1 intensity ratios consistent with their formation as slowly cooled cumulates basaltic eucrites exhibit a large range of m1 intensity ratios all of which are consistently higher than the diogenites and cumulate eucrites this example illustrates how the m1 intensity ratio can be a used as a tool for characterizing the cooling history of remotely detected pyroxene dominated rocks

recent advances and future prospects of the u th and u pb chronometers applicable to archaeology abstract the u th chronometer has revolutionized quaternary science in the last few decades and can now be considered a well established mature technique with growing application in archaeology as an alternative to 14 c dating and osl reaching well beyond the cutoff for both these methods applying the u pb technique to material within a time frame of interest to archaeology is a challenge only recently overcome with enormous potential for future development and use in terms of range u th can generally date material of between a few years and as much as 600 ka while u pb is best suited to material of 1 million years and older u th dating is typically precise with error margins of better than 1 routinely achievable for material of the last interglacial age or younger such precision is possible with u pb dating in the mid quaternary but most ages have uncertainties in the 5 10 range carbonates are the most desirable u series target material with closed system behaviour being particularly important for u th dating making inorganic deposits such as speleothems secondary cave carbonates tufa and calcrete ideal some biogenic carbonates such as coral and eggshell are often amenable to u series dating but less ideal material such as fossil teeth bone and mollusc shell usually continue to gain uranium after deposition meaning accurate ages cannot be calculated in all cases the importance of a thorough understanding of the context of dated material cannot be overstated in this contribution we review u th and u pb dating through an archaeological lens focussing on the methods themselves how to best interpret published data and how best to avoid common pitfalls we highlight the major successes through a number of case studies and provide an overview of what we believe to be the future directions of this field

spectral analysis of the bright materials on the asteroid vesta vesta spectra have prominent near infrared absorption bands characteristic of pyroxenes indicating a direct link to the howardite eucrite and diogenite meteorites many localized dark and bright materials are present on vesta s surface here we focus on the bright material bm units to determine their spectral properties their origin the presence of mineralogical phases different from pyroxenes and whether different bright units share a common lithology vir the visible and infrared spectrometer onboard dawn allows us to first do a detailed analysis of the spectral properties of a large number of bright material units on vesta including examples of the different morphological classes the spectral parameters used are band centers band depths and band area ratio bar for the pyroxene bands at 0 9 and 1 9 m the mineralogies of most bright regions are consistent with those of the howardite eucrite and diogenite meteorites typical of vesta s surface we find that bright material units exhibit the full range of hed pyroxene composition from eucrites to diogenites large part of the bright materials are eucrite rich according with the vesta s mineralogy in most cases the bright materials have the same mineralogy of the surrounding terrain but have larger band depth values the band depths can be related to the abundance of the absorbing minerals the abundance of fe2 grain size and or to the abundance of opaque materials we found a positive correlation between albedo and band depth which suggests that the grain size is not the main factor responsible for the higher albedo the analysis of the band parameters indicates that most of the bright materials excluding the few olivine rich units represent fresh uncontaminated vestan pyroxenes from a variety of lithologies exposed from beneath the surface by impacts

laser ablation depth profiling of u series and sr isotopes in human fossils we have explored laser depth profiling to obtain data sets for u series as well as sr analyses laser probing with an 81 m spot size allows for the exploration of low uranium domains of up to 400 m below the outer surface in tooth enamel these low u domains will contain sr isotope compositions of the individual that are least affected by diagenetic sr overprints the small holes drilled for u surveying are not visible to the naked eye using larger spot sizes of around 233 m laser drilling can be used to obtain reliable u series isotope data to a depth of approximately 1000 m in enamel and around 1300 m in bone furthermore meaningful 87sr 86sr isotope data can also be obtained with this spot size using our sampling strategy the overall damage to a human tooth is minute as demonstrated on a neanderthal tooth from moula guercy we expect that laser ablation depth profiling will become routine for gaining insights into the age of human fossils and the migrations of ancient humans

re evaluating the late quaternary fossil mammal assemblage of seton rockshelter kangaroo island south australia including the evidence for late surviving megafauna it is widely accepted that most larger australian vertebrates were extinct by 40 ka the reliability of 20 ka radiocarbon 14c ages on charcoal stratigraphically associated with sthenurine short faced kangaroo tooth fragments from seton rockshelter kangaroo island have therefore proven contentious some researchers have argued these fossils were in situ while others have claimed they were reworked to address this we obtained new 14c ages on bones from the site these bone ages are not only consistent with earlier charcoal ages but are in near perfect stratigraphic order providing strong support for the site s stratigraphic integrity our analyses indicate units aged 21 17 ka were primarily accumulated by tasmanian devils sarcophilus harrisii and owls tyto species after which humans became the primary accumulation agent the tight chronology faunal trends and current lack of evidence for older layers from which specimens could have been reworked suggest the sthenurine remains may be in situ however because attempts to directly date sthenurine material failed we cannot confidently assert that they survived to this time therefore seton rockshelter may be best excluded from the pleistocene extinction debate until the site can be re excavated and more conclusive evidence collected including more complete or directly datable sthenurine remains copyright 2015 john wiley sons ltd

esr and esr u series chronology of the middle pleistocene site of tourville la riviere normandy france a multi laboratory approach tourville la riviere normandy france is one of the rare middle pleistocene palaeoanthropological localities of northern france electron spin resonance esr and combined esr u series dating methods were independently applied by different teams on sediments and teeth from this site the present work provides an overview of this multi laboratory dating work by integrating a description and discussion of the methodologies employed and results obtained results confirm that the esr u series analyses of the teeth are greatly dependent on the u uptake histories of the dental tissues although all teeth come from the same archeological level the samples analysed by each team display two different patterns for the u series data this is most likely related to the different sampling areas selected by each team and may be interpreted as the result of local variations in the geochemical conditions of the surrounding environment concerning the esr dating of optically bleached quartz grains the use of the multiple centre approach seems crucial when dating such fluvial and fluvio lacustrine sediments our results also confirm the great potential of the ti h centre to date late middle pleistocene deposits despite some expected discrepancies related to the independent use of parameters and approaches by the different teams involved in this multi laboratory study the whole esr and esr u series data set collected from tourville la riviere locality consistently correlates stratigraphic levels d1 to i and associated human occupation to mis7

ams radiocarbon dating of middle and upper palaeolithic bone in the british isles improved reliability using ultrafiltration recent research at the oxford radiocarbon accelerator unit orau has shown that ultrafiltration of gelatin from archaeological bone can in many instances remove low molecular weight contaminants these can sometimes be of a different radiocarbon age and unless removed may severely influence results particularly when dating bones greater than two to three half lives of 14c in this study this methodology is applied to samples of late middle and early upper palaeolithic age from the british isles in many instances the results of redating invite serious reconsideration of the chronology for these periods copyright 2006 john wiley sons ltd

petrogenesis of the nakhlite meteorites evidence from cumulate mineral zoning abstract a simple igneous petrogenesis for the meteorite nakhla has previously been called into question because mg fe ratios in olivine indicate substantial disequilibrium between the predominant cumulus minerals olivine and augite comparative analyses of simulated diffusive zoning and the observed cumulus mineral zoning for all three nakhlites nakhla governador valadares and lafayette show that their current compositions do not necessarily reflect parental magma compositions instead diffusion has altered primary cumulus compositions to varying degrees nakhla being the least affected and lafayette being almost completely re equilibrated only the cores of augite grains in nakhla and governador valadares appear to have preserved their original compositions mineral zoning in each meteorite is strongly concentric around mesostasis areas suggesting that reaction with intercumulus liquid has controlled the observed zoning the presence of pigeonite and orthopyroxene overgrowths in nakhla and governador valadares and of poikilitic orthopyroxene enclosing olivine relicts in lafayette indicate substantial late magmatic reactions two pyroxene geothermometry for lafayette indicates temperatures around 950 c suggesting subsolidus equilibration as well the nakhlites appear to be a series of relatively simple cumulate rocks which have undergone various amounts of late magmatic and subsolidus diffusion possibly reflecting their relative positions in a cooling cumulate pile

visible to near infrared optical properties of pure synthetic olivine across the olivine solid solution olivine exhibits highly diagnostic absorption features across visible to near infrared vnir wavelengths due to electronic transitions of fe2 in its crystal structure the properties of these absorptions vary with composition enabling compositional analysis of olivine through vnir spectroscopy both in the laboratory and through remote sensing previous analyses of these trends have relied on natural olivine samples which are influenced by the presence of minor cations that can affect the diagnostic absorptions we conduct a systematic analysis of a suite of synthetic pure mg fe olivine samples with vnir 300 2600 nm reflectance spectroscopy and quantitative spectral deconvolutions from the full suite of samples described and characterized by dyar et al 2009 we identify a small suite of well characterized and chemically pure olivine samples that demonstrates consistent and reliable spectral reflectance properties across visible to near infrared wavelengths this suite covers the stoichiometric olivine solid solution from x mg mg fe 0 to x 70 fo to fo70 because of their tight compositional control these synthetic samples improve on previous analyses of natural samples the results of this study provide a new standard for spectral reflectance properties of olivine across visible to near infrared wavelengths for the compositions present in the suite we present updated data on the trends in olivine band position as a function of olivine composition which are the basis for remote compositional evaluation of olivine with visible to near infrared reflectance spectroscopy for these reasons these improved olivine band position trends are of major importance to remote compositional analyses of terrestrial planets

vesta as the howardite eucrite and diogenite parent body implications for the size of a core and for large scale differentiation if vesta is the parent body of the howardite eucrite and diogenite hed meteorites then geo chemical and petrologic constraints for the meteorites may be used in conjunction with astronomical constraints for the size and mass of vesta to 1 determine the size of a possible metal core in vesta and 2 model the igneous differentiation and internal structure of vesta the density of vesta and petrologic models for hed meteorites together suggest that the amount of metal in the parent body is 25 mass with a best estimate of 5 assuming no porosity for a porosity of up to 5 in the silicate fraction of the asteroid the permissible metal content is 30 these results suggest that any metal core in the hed parent body and vesta is not unusually large a variety of geochemical and other data for hed meteorites are consistent with the idea that they originated in a magma ocean it appears that diogenites formed by crystal accumulation in a magma ocean cumulate pile and that most noncumulate eucrites excepting such eucrites as bouvante and statinem formed by subsequent crystallization of the residual melts modelling results suggest that the hed parent body is enriched in rare earth elements by a factor of 2 5 3 5 relative to ci chondrites and that it has approximately chondritic mg si and al sc ratios stokes settling calculations for a vesta wide nonturbulent magma ocean suggest that early crystallizing magnesian olivine orthopyroxene and pigeonite would have settled relatively quickly permitting fractional crystallization to occur but that later crystallizing phases would have settled or floated an order of magnitude more slowly allowing instead a closer approach to equilibrium crystallization for the more evolved eucritic melts this would have inhibited the formation of a plagioclase flotation crust on vesta plausible models for the interior of vesta which are consistent with the data for hed meteorites and vesta include a metal core 130 km radius an olivine rich mantle 65 220 km thick a lower crustal unit 12 43 km thick composed of pyroxenite from which diogenites were derived and an upper crustal unit 23 42 km thick from which eucrites originated the present shape of vesta with 60 km difference in the maximum and minimum radius suggests that all of the crustal materials and possibly some of the underlying olivine from the mantle could have been locally excavated or exposed by impact cratering

detections and geologic context of local enrichments in olivine on vesta with vir dawn data the magmatism characterizing the early history of the asteroid vesta has long been investigated with the mafic and ultramafic meteorites howardite eucrite and diogenite hed the lack of geologic context for the meteorites however has limited its understanding here we use the visible to near ir vir orbital observations of vesta s surface to detect relative enrichments in olivine and to study the associated geologic features because the near ir signature of olivine on vesta s surface is subtle relative to the widespread pyroxene absorption bands a method was developed to distinguish olivine enrichments from admixture of pyroxenes with high fe2 m1 dark material and potential fe bearing glass relative enrichment of olivine 50 60 vol is found in 2 5 km wide morphologically fresh areas our global survey reveals a dozen of these areas clustering in the eastern hemisphere of vesta the hemispherical coincidence with a widespread low enrichment in diogenite like pyroxene suggests the presence of a distinct compositional terrain on the central mound of the rheasilvia impact basin no olivine enrichment was found suggesting the absence of an olivine dominated mantle above the basin s excavation depth or alternatively a low amount of olivine homogeneously mixed with diogenite like pyroxenes rare olivine enriched areas in close proximity to diogenite like pyroxene are found as part of material ejected by the rheasilvia impact such cooccurrence is reminiscent of local ultramafic lithologies within the crust the possible formation of such lithologies on vesta is supported by some hed meteorites dominated by olivine and orthopyroxene

the polymict eucrites the polymict eucrites are a suite of about 14 polymict achondritic meteorites that contain at least 90 vol of eucritic material and are found both in antarctica and elsewhere they are part of a continuum of polymict breccias that includes howardites and polymict diogenites rare gas data suggest that some are gas rich regolith breccias the clasts contained in polymict eucrites sample a variety of lithologies from their parent body and include eucritic clasts alkali enriched eucrites pyroxene cumulate eucrites two pyroxene mafic rocks possibly feldspar cumulate eucrites diogenites fayalitic lithologies and a variety of other mineral clasts the eucritic clasts are probably samples of near surface lithologies on the parent body but the presence of two pyroxene mafic rocks is considered to be evidence of magmatic activity at pressures in excess of 1 kbar in the parent body partial melt models may explain some of the diversity among the clasts but cumulus processes are believed to have been important if pressures greater than 1 kbar are confirmed then the basaltic achondrite parent body bap must have a diameter in excess of 200 km the variety of lithologies suggests that not all basaltic achondrites are samples of igneous rocks formed by single stage melting of a chondritic asteroid but are instead samples of an evolved and diverse crust produced by serial magmatism

sedimentation re sedimentation and chronologies in archaeologically important caves problems and prospects excavations in the photic zones of caves have provided cornerstone archaeological sequences in many parts of the world before the appearance of modern dating techniques cave deposits provided clear evidence for the antiquity relative ages and co occurrence of ancient human remains material culture and fauna earlier generations of archaeologists had generally rather limited understanding of taphonomic and depositional processes but the twentieth century saw considerable improvement in excavation and analytical techniques the advent of modern dating and chronological methodologies offers very powerful tools for the analysis of cave fill deposits and this has resulted in the recognition of chronological incoherence in parts of some sites with consequent re evaluation of previous archaeological disputes obtaining multiple dates per context provides a means to assess the integrity and coherence of the archaeological and environmental records from cave fills in the case of the haua fteah libya this technique allowed the recognition of chronological coherence in low energy depositional environments and limited recycling in high energy contexts we provide a conceptual model of the relationship between recycling sedimentation rate and process energy high resolution investigation enables recognition of the complexity of the formation of cave sequences thus an increasingly sophisticated understanding of human behaviour and environmental relationships in the past and potentially gives a new life to old data

geologic map of the northern hemisphere of vesta based on dawn framing camera fc images abstract the dawn framing camera fc has imaged the northern hemisphere of the asteroid 4 vesta at high spatial resolution and coverage this study represents the first investigation of the overall geology of the northern hemisphere 22 90 n quadrangles av 1 2 3 4 and 5 using these unique dawn mission observations we have compiled a morphologic map and performed crater size frequency distribution csfd measurements to date the geologic units the hemisphere is characterized by a heavily cratered surface with a few highly subdued basins up to 200 km in diameter the most widespread unit is a plateau cratered highland unit similar to although of lower elevation than the equatorial vestalia terra plateau large scale troughs and ridges have regionally affected the surface between 180 e and 270 e these tectonic features are well developed and related to the south pole veneneia impact saturnalia fossae trough unit elsewhere on the hemisphere they are rare and subdued saturnalia fossae cratered unit in these pre rheasilvia units we observed an unexpectedly high frequency of impact craters up to 10 km in diameter whose formation could in part be related to the rheasilvia basin forming event the rheasilvia impact has potentially affected the northern hemisphere also with s n small scale lineations but without covering it with an ejecta blanket post rheasilvia impact craters are small

absolute dating of hominids and palaeolithic artifacts of the cave of la chaise de vouthon charente france abstract two adjacent chambers of the cave of la chaise grotte de bourgeois delaunay b d and grotte suard have been studied both were partly filled with detrital sediments containing lower and middle palaeolithic artifacts and skeletal remains of pre neanderthalian hominids layers of stalagmitic calcite occur interstratified in the sediments of both chambers dates obtained by 230th 234u ratios have provided a time scale for hominid and cultural evolution as represented in this cave in b d the lower travertine rests on a breccia containing cranial remains of juvenile neanderthals the base of the travertine dates to 151 15 ky ky 1000 years bp the top of the travertine yields a date of 112 5 ky the travertine contains pollen of an interglacial flora overlying detrital sediments 1 2 m in thickness contain artifacts transitional from acheulian to mousterian industries they are capped by a travertine layer 7 whose base is dated at 100 6 ky and which is capped by stalagmites ranging in age down to 58 7 ky overlying the travertine is sediment containing first mousterian and then aurignacian artifacts near the base of the sediments filling grotte suard is a stalagmite layer dated to 249 30 ky it contains interglacial pollen and presumably dates to the beginning of the isotope stage 7 interglacial neanderthaloid hominid teeth and cranial fragments are found scattered through the overlying sediments up to a capping stalagmitic layer whose base is dated at 101 7 ky the best described hominids from suard are from a section that was probably overlying the capping stalagmite the capping stalagmite is temporally correlated with layer 7 of b d

geoarchaeological finds below liang bua flores indonesia a split level cave system for homo floresiensis we report on new geoarchaeological finds in a recently discovered cave chamber liang bawah cave under neath positioned below liang bua on the island of flores indonesia where the type specimen for homo floresiensis was recovered from late pleistocene sediment at the rear of liang bua a 23 m long shaft inclined at 60 leads to a lower chamber measuring 23 m x 24 m x 5 m high about half the size of liang bua stone artefacts and bones were found shallowly buried in rubble at the base of the shaft and around a 5 m high mud mound that fills the northwest sector of liang bawah we recovered 17 stone artefacts made from chert and volcanics and more than 220 well preserved bone elements belonging to endemic giant rats pigs primates small murid rodents bats and introduced species multi collector inductively coupled plasma mass spectrometer mc icpms analysis of uranium and thorium in carbonate coatings on four bones yielded ages of similar to 240 180 ka endemic giant rat femur similar to 110 60 ka unidentified phalanx similar to 33 23 ka pig skull fragment and similar to 7 3 ka giant rat femur which overlap with the similar to 95 to 17 ka occupation of liang bua by h floresiensis the similar to 33 23 ka age of the pig skull fragment indicates that sus sp may have dispersed into island southeast asia earlier than previously recognised the passageway at the rear of liang bawah and a currently buried front entrance represent two possible transport paths for cultural and faunal material to the cave chamber analysis of the geomorphic evolution of liang bawah shows that it may have been a late pleistocene depocentre for material transported from the occupation chamber of liang bua and a repository for human subsistence refuse or pit fall trap via the rear passage these physical attributes and the antiquity of the faunal remains found thus far indicate that liang bawah could contain an archive of the late pleistocene and potentially remains of h floresiensis c 2015 elsevier b v all rights reserved

a test of uranium series dating of fossil tooth enamel results from tournal cave france abstract a series of well preserved mammal bones and horse teeth was analyzed from archaeological levels of tournal cave magdalenian aurignacian and mousterain to test the hypothesis that well crystallized enamel behaves more as a closed system than does whole bone the isotopic composition of bones and tooth enamels from this deposit meet criteria for confidence and gave no reasons to suspect contamination or open system behavior two samples for which231pa could be analyzed showed internal concordance with the respective230th ages in spite of the favourable isotopic criteria however comparison of the u series ages of the bones and the tooth enamel with stratigraphic position and14c control indicated the dates were not meaningful in general both bones and tooth enamels gave ages too young although some were clearly too old neither group showed any systematic increase of age with stratigraphic depth tooth enamel therefore shows no advantage over bone for u series dating for this site in tournal cave both bones and enamel are apparently open to u which is probably cycling as a consequences of post depositional groundwater movement

revisiting the esr chronology of the early pleistocene hominin occupation at vallparadis barcelona spain abstract esr dating was applied to fossil teeth and optically bleached quartz grain samples from two units of the sequence at vallparadis barcelona spain weighted mean esr age estimates of 858 87 ka and 849 48 ka were obtained for evt 7 which includes the archaeological level 10 and evt 8 respectively these results are in good agreement with the existing magneto biostratigraphic framework that constrain these deposits between 780 and 990 ka and indicate that vallparadis evt 7 has a chronology very close to that of atapuerca gran dolina td 6 spain

precise timing of the last interglacial period from mass spectrometric determination of thorium 230 in corals the development of mass spectrometric techniques for determination of 230 th abundance has made it possible to reduce analytical errors in 238 u 234 u 230 th dating of corals even with very small samples samples of 6 x 10 8 atoms of 230 th can be measured to an accuracy of 3 percent 2 and 3 x 10 10 atoms of 230 th can be measured to an accuracy of 0 2 percent the time range over which useful age data on corals can be obtained now ranges from about 50 to about 500 000 years for young corals this approach may be preferable to 14 c dating the precision with which the age of a coral can now be determined should make it possible to critically test the milankovitch hypothesis concerning pleistocene climate fluctuations analyses of a number of corals that grew during the last interglacial period yield ages of 122 000 to 130 000 years the ages coincide with or slightly postdate the summer solar insolation high at 65 n latitude which occurred 128 000 years ago this supports the idea that changes in pleistocene climate can be the result of variations in the distribution of solar insolation caused by changes in the geometry of the earth s orbit and rotation axis

a reassessment of the age of the fauna from cumberland bone cave maryland middle pleistocene using coupled u series and electron spin resonance dating esr

composition and mineralogy of dark material units on vesta vesta is the asteroid with the largest albedo variation among the known rocky solar system objects and shows a widespread occurrence of dark material dm and bright material bm units in the first observation phases by the dawn spacecraft two main extensions of low albedo areas were identified on vesta and found to be closely correlated with carbonaceous oh rich material in this work we use the hyperspectral data provided by the vir dawn imaging spectrometer onboard dawn to detect and analyze individual well defined dark material units we define dm units assuming a relative criterion i e reflectance lower than the surroundings by coupling visible and infrared images of the same area we are able to select real dark material units discarding false detections created by shadowing effects a detailed final catalogue of 123 dark units is presented containing the geographical parameters and the main spectral characteristics for each unit independently of the geological context of the dark units all dms show similar spectral properties dominated by the pyroxene absorption features as is the average spectrum of vesta this finding suggests a similar composition with the presence of darkening agents that also weaken pyroxene band depths the majority 90 of the dm units shows a positive correlation between low albedo and an oh band centered at 2 8 lm confirming the hypothesis that the darkening agents are carbonaceous chondrites probably delivered by low velocity impacts of primitive asteroids a comparison with laboratory spectra allows us to better constrain the size and the composition of the darkening agents these dm areas seem to be made of eucritic material the regolith grain size seems to be nearly constant around an average value of 25 lm and is quite homogenous at least in the first hundreds of meters beneath the vesta surface suggesting similar processing mechanisms for both dm and bm

a magma ocean on vesta core formation and petrogenesis of eucrites and diogenites abstract available evidence strongly suggests that the hed howardite eucrite diogenite meteorites are samples of asteroid 4 vesta abundances of the moderately siderophile elements ni co mo w and p in the hed mantle indicate that the parent body may have been completely molten during its early history during cooling of a chondritic composition magma ocean equilibrium crystallization is fostered by the suspension of crystals in a convecting magma ocean until the crystal fraction reaches a critical value near 0 80 when the convective system freezes and melts segregate from crystals by gravitational forces the extruded liquids are similar in composition to main group and stannern trend eucrites and the last pyroxenes to precipitate out of this ocean before convective lockup span the compositional range of the diogenites subsequent fractional crystallization of a main group eucrite liquid which has been isolated as a body of magma produces the nuevo laredo trend and the cumulate eucrites the predicted cumulate mineral compositions are in close agreement with phase compositions analyzed in the cumulate eucrites thus eucrites and diogenites are shown to have formed as part of a simple and continuous crystallization sequence starting with a magma ocean environment on an asteroidal size parent body that is consistent with vesta

hiding in the howardites unequilibrated eucrite clasts as a guide to the formation of vesta s crust 204 howardites in the national meteorite collection at the smithsonian were examined for the presence of fine grained eucrite clasts with the goal of better understanding the formation of the uppermost crust of asteroid 4vesta eight clasts were identified and characterized in terms of their textures and mineral chemistry and their degree of thermal metamorphism was assessed the paucity of fine grained eucrites both within the unbrecciated eucrites and as clasts within the howardites suggests that they originate from small scale units on the surface of vesta most likely derived from partial melting six of the eight clasts described were found to be unequilibrated meaning that they preserve their original crystallization trends the vast majority of eucrites are at least partially equilibrated making these samples quite rare and important for deciphering the petrogenesis of the vestan crust biomodal grain populations suggest that eucrite melts often began crystallizing pyroxene and plagioclase during their ascent to the surface where they were subject to more rapid cooling crystallization and later metasomatism pyroxene compositions from this study and prior work indicate that the products of both primitive and evolved melts were present at the vestan surface after its formation two howardite thin sections contained multiple eucrite composition clasts with different crystallization and thermal histories this mm scale diversity reflects the complexity of the current day vestan surface that has been observed by dawn

extremely large variations of atmospheric 14c concentration during the last glacial period a long record of atmospheric 14c concentration from 45 to 11 thousand years ago ka was obtained from a stalagmite with thermal ionization mass spectrometric 230th and accelerator mass spectrometric 14c measurements this record reveals highly elevated 14c between 45 and 33 ka portions of which may correlate with peaks in cosmogenic 36cl and10be isotopes observed in polar ice cores superimposed on this broad peak of 14c are several rapid excursions the largest of which occurs between 44 3 and 43 3 ka between 26 and 11 ka atmospheric 14c decreased from 700 to 100 per mil modulated by numerous minor excursions carbon cycle models suggest that the major features of this record cannot be produced with solar or terrestrial magnetic field modulation alone but also require substantial fluctuations in the carbon cycle

global crustal metamorphism of the eucrite parent body abstract we conducted a petrologic study of 18 equilibrated eucrites with the goal of understanding the formation and evolution of the crust of asteroid 4 vesta the likely source of eucrite meteorites their textures indicate that eucrites were basaltic igneous rocks but modified by postcrystallization brecciation recrystallization and impact melting recrystallized rocks are the most common among clasts in the eucrites impact melt breccias are rare equilibration temperatures of the metamorphic clasts range from 700 to 1000 c with most in the 800 900 c range complex exsolution and recrystallization textures in pyroxenes suggest that eucrites cooled very slowly from high peak temperatures after reheating this extended period of thermal metamorphism requires a high interior temperature in a vesta sized body this metamorphism could have taken place during and shortly after crust formation we suggest the crust of vesta evolved through the eruption rapid cooling and subsequent burial and reheating of lava flows as the crust grew in thickness the depth of burial increased causing temperatures to rise and leading to global metamorphism this resulted in only a small percentage of unequilibrated eucrites only the last few percent of basalts erupted would not be metamorphosed and a wide range of metamorphic temperatures and durations for the equilibrated eucrites

complexities in pyroxene compositions derived from absorption band centers examples from apollo samples hed meteorites synthetic pure pyroxenes and remote sensing data we reexamine the relationship between pyroxene composition and near infrared absorption bands integrating measurements of diverse natural and synthetic samples we test an algorithm plc involving a two part linear continuum removal and parabolic fits to the 1 and 2 m bands a computationally simple approach which can easily be automated and applied to remote sensing data employing a suite of synthetic pure pyroxenes the plc technique is shown to derive similar band centers to the modified gaussian model plc analyses are extended to natural pyroxene bearing materials including 1 bulk lunar basalts and pyroxene separates 2 diverse lunar soils and 3 hed meteorites for natural pyroxenes the relationship between composition and absorption band center differs from that of synthetic pyroxenes these differences arise from complexities inherent in natural materials such as exsolution zoning mixing and space weathering for these reasons band center measurements of natural pyroxene bearing materials are compositionally nonunique and could represent three distinct scenarios 1 pyroxene with a narrow compositional range 2 complexly zoned pyroxene grains or 3 a mixture of multiple pyroxene or nonpyroxene components therefore a universal quantitative relationship between band centers and pyroxene composition cannot be uniquely derived for natural pyroxene bearing materials without additional geologic context nevertheless useful relative relationships between composition and band center persist in most cases these relationships are used to interpret m3 data from the humboldtianum basin four distinct compositional units are identified 1 mare humboldtianum basalts 2 distinct outer basalts 3 low ca pyroxene bearing materials and 4 feldspathic materials

a comparative dating study of bones from little hoyle cave south wales u k abstract four animal bones from little hoyld cave an upper palaeolithic site near tenby in southwest wales have been the subject of a comparative dating study each bone has been dated by three methods radiocarbon amino acid racemization and uranium series disequilibrium the latter based on a new approach to fossil bones the results show a good agreement between the methods with ages generally overlapping well within the quoted 2 uncertainties the bones are derived from a cold climate fauna and the mean date of 17 85 0 12 ka bp indicates that they are contemporary with the main late devensian ice advance when the ice sheet reached within 30 km of the cave the date is very similar to that of the paviland burial 18 46 0 34 ka bp bm 374 in nearby gower which was also ice free during the late devensian glacial maximum

on the limits of using combined u series esr method to date fossil teeth from two early pleistocene archaeological sites of the orce area guadix baza basin spain abstract article history received 6 june 2011available online 9 february 2012keywords combined u series esr dating methodfossil teethfuente nueva 3barranco leonorceearly pleistocene the combined u series electron spin resonance esr dating method was applied to nine teeth from twoearly pleistocene archaeological sites located in the orce area guadix baza basin southern spain fuentenueva 3 fn 3 and barranco leon bl the combination of biostratigraphy and magnetostratigraphy placesboth sites between the olduvai and jaramillo subchrons 1 78 1 07 ma our results highlight the dif culty of dating such old sites and point out the limits of the combined u series esr dating method based on the us model we identi ed several sources of uncertainties that may lead toinaccurate age estimates seven samples could not be dated because the dental tissues had 230 th 234 u ac tivity ratios higher than equilibrium indicating that uranium had probably leached from these tissues it washowever possible to calculate numerical estimates for two of the teeth both from fn 3 one yielded a middlepleistocene age that seems to be strongly underestimated the other provided an age of 1 19 0 21 ma inagreement with data obtained from independent methods the latter result gives encouragement thatthere are samples that can be used for routine dating of old sites 2012 university of washington published by elsevier inc all rights reserved

mobility of early islanders in the philippines during the terminal pleistocene early holocene boundary pxrf analysis of obsidian artefacts abstract the philippine archipelago spans over two distinct biogeographic zones sundaland and wallacea we report in this paper on finds from ilin island just off the coast of sw mindoro and el nido in northern palawan while the island of palawan is linked to sundaland mindoro and ilin island belong to wallacea east of huxley s line ongoing archaeological investigations at bubog 1 rockshelter on ilin island and ille cave rockshelter in northern palawan delivered obsidian artefacts found in terminal pleistocene and early holocene layers pxrf analysis of the obsidian samples from mindoro and palawan shows that they were coming from the same yet unknown source they clearly indicate that the two distinct paleogeographical regions were linked to each other suggesting human interaction and maritime networks as early as ca 12ka bp the results of this study contribute substantially to our understanding of the mobility of early islanders during the terminal pleistocene and the processes of human island adaptation and enhance our current knowledge of subsistence strategies across the region

geologic mapping of vesta from 1994 hubble space telescope images we utilize the 56 images of asteroid 4 vesta obtained through four mineralogically diagnostic filters by the hubble space telescope zellneret al 1997 icarus to construct a geologic map vesta s surface is found to be geologically diverse and to be dichotomous at a hemispheric scale the eastern hemisphere longitude definition from thomaset al 1997 icarus is dominated by units interpreted to be impact excavated plutonic material composed of magnesium rich and calcium poor pyroxene the mineralogy of this region is most analogous to diogenite meteorites several eastern hemisphere units which have the deepest and broadest 1 m absorption bands may contain a substantial olivine component the locations of these units are consistent with a previous map based on rotationally resolved groundbased spectroscopy gaffey 1997 icarus the western hemisphere is dominated by units interpreted to consist of a single component of iron rich and relatively calcium rich pyroxene analogous to surface basalts such as eucrite meteorites we investigate the spectral properties of 20 representative surface regions and find a correlation between the 1 m absorption band depth and albedo the units with lower albedos have shallower band depths such a relation could arise from differences in lithologies differences in surface particle sizes or from a weathering effect which decreases albedo and band depth over time because of vesta s geologic diversity and hemispheric dichotomy it is apparent that any major impact events such as those possibly related to the formation of the vesta family binzel and xu 1993 science260 186 191 did not globally resurface the planet the spectral evidence for remnants of a basaltic crust implies that the oldest units on the surface date back to the time of their emplacement most likely 4 5 byr ago if a weathering process exists which alters the albedo then the lowest albedo units such as the feature with the proposed name olbers most likely represent remnants of vesta s ancient basaltic crust

in situ u series dating by laser ablation multi collector icpms new prospects for quaternary geochronology the capabilities and potential applications of in situ dating of quaternary materials using laser ablation mc icpms are explored 234 u 238 u and 230 th 234 u can be measured with precision sufficient for dating at a spatial resolution of 100mm or better in samples that contain as a little as 1 ppm uranium moreover u and th concentrations and u series isotope ratios can be continuously profiled to determine changes in age that occur with sample growth e g in speleothems these capabilities additionally permit the dating of bones teeth and possibly molluscs which are subject to post mortem open system behaviour of useries isotopes and can be employed to elucidate processes of u series migration during weathering and diagenesis a drawback of laser ablation mc icpms is that it cannot in general provide u series age estimates with the high precision and accuracy of conventional tims or solution mc icpms methods however sample preparation is straightforward the amount of sample consumed negligible and it can be used to rapidly characterise or screen and select samples from which more precise and accurate dates can be obtained using conventional methods given further instrumental developments and the establishment of suitable matrix matched standards for carbonates and other materials we foresee that laser ablation mc icpms will play an increasingly important role in quaternary dating research r 2005 published by elsevier ltd

revised radiocarbon ages on woolly rhinoceros coelodonta antiquitatis from western central scotland significance for timing the extinction of woolly rhinoceros in britain and the onset of the lgm in central scotland woolly rhinoceros bones from a number of sites in britain have been ams radiocarbon dated following ultrafiltration pre treatment these determinations give a coherent set of ages between 50 and c 35 cal ka bp the youngest 35 864 34 765 cal bp come from the area around bishopbriggs in western central scotland and are derived from glaciofluvial sand and gravel overlain by till both deposited during the last glacial maximum lgm glaciation a previous radiocarbon date from the site suggested that woolly rhinoceros lived c 27 14c ka bp and the region was ice free at the time this date has had significant influence on the timing of extinction of woolly rhinoceros and the onset of glaciation over britain during the lgm the new dates revise this earlier determination and confirm that woolly rhinoceros became extinct in britain after c 35 cal ka bp that central scotland was ice free at this time and glaciation extended across this region sometime after 35 cal ka bp

esr and u series analyses of faunal material from cuddie springs nsw australia implications for the timing of the extinction of the australian megafauna abstract the timing and cause of late pleistocene faunal extinctions in australia are subjects of a debate that has become polarised by two vigorously defended views one contends that the late pleistocene extinction was a short event caused by humans colonising the australian continent whereas the other promotes a gradual demise of the fauna over a period of at least 10 20 ka due to a combination of climatic changes and ecological pressures by humans cuddie springs is central to this debate as it is the only site known in continental australia where archaeological and megafauna remains co occur we have analysed more than 60 bones and teeth from the site by laser ablation icp ms to determine u and th concentrations and distributions and those with sufficiently high u concentrations were analysed for u series isotopes twenty nine teeth were analysed by esr these new results as well as previously published geochronological data contradict the hypothesis that the clastic sediments of stratigraphic unit 6 su6 are in primary context with the faunal archaeological and other materials found in su6 and that all have ages consistent with the optically stimulated luminescence osl estimates of 30 36 ka these young osl results were used to argue for a relatively recent age of the extinct fauna our results imply that su6 is either significantly older than the osl results or that a large fraction of the faunal material and the charcoal found in su6 was derived from older lateral deposits our u and th laser ablation icpms results as well as the ree profiles reported by trueman et al 2008 comparing rates of recystallisation and the potential for preservation of biomolecules from the distribution of trace elements in fossil bones c r palevol general paleontology taphonomy and fossilization 7 145 158 contradict the interpretation of previously reported rare earth element compositions of bones and the argument based thereon for the primary context of faunal material and clastic sediments in su6 layers

high calcium pyroxene as an indicator of igneous differentiation in asteroids and meteorites our analyses of high quality spectra of several s type asteroids 17 thetis 847 agnia 808 merxia and members of the agnia and merxia families reveal that they include both low and highcalcium pyroxene with minor amounts of olivine 0 4 high calcium pyroxene is a spectrally detectable and petrologically important indicator of igneous history and may prove critical in future studies aimed at understanding the history of asteroidal bodies the silicate mineralogy inferred for thetis and the merxia and agnia family members requires that these asteroids experienced igneous differentiation producing broadly basaltic surface lithologies together with 4 vesta and its smaller vestoid family members and the main belt asteroid 1489 magnya these new asteroids provide strong evidence for igneous differentiation of at least five asteroid parent bodies based on this analysis of a small subset of the near infrared asteroid spectra taken to date with spex at the nasa irtf we expect that the number of known differentiated asteroids will increase consistent with the large number of parent bodies inferred from studies of iron meteorites

high resolution analysis of uranium and thorium concentration as well as u series isotope distributions in a neanderthal tooth from payre ardeche france using laser ablation icp ms we have mapped u 238 u and th 232 th elemental concentrations as well as u series isotope distributions in a neanderthal tooth from the middle palaeolithic site of payre using laser ablation icp ms the u concentrations in an enamel section varied between 1 and 1500 ppb the u concentration maps show that u migration through the external enamel surface is minute the bulk of the uranium having migrated internally via the dentine into the enamel the uranium migration and uptake is critically dependent on the mineralogical structure of the enamel increased u concentrations are observed along lineaments some of which are associated with cracks and others may be related to intra prismatic zones or structural weaknesses reaching from the dentine into the enamel the uranium concentrations in the dentine vary between about 25 000 and 45 000 ppb our systematic mapping of u concentration and u series isotopes provides insight into the time domain of uaccumulation most of the uranium was accumulated in an early stage of burial with some much later overprints none of the uranium concentration and u series profiles across the root of the tooth complied with a single stage diffusion adsorption d a model that is used for quality control in u series dating of bones and teeth nevertheless in the domains that yielded the oldest apparent u series age estimates u leaching could be excluded this means that the oldest apparent u series ages of around 200 ka represent a minimum age for this neanderthal specimen this is in good agreement with independent age assessments 200 230 ka for the archaeological layer in which it was found the th elemental concentrations in the dental tissues were generally low between about 1 and 20 ppb and show little relationship with the nature of the tissue 2008 elsevier ltd all rights reserved

absolute dating by uranium series disequilibrium of bones from the cave of la chaise de vouthon charente france animal bones associated with palaeolithic artefacts and skeletal remains of early hominids from the cave of la chaise de vouthon have been dated using a new approach to uranium series dating of bone speleothem cave calcite interstratified with bone bearing sediments in the two chambers of grotte bourgeois delaunay and grotte suard have previously been dated by the 230th 234 u method this provides a chronological control for the bone ages for which the method is still at an experimental stage a good agreement is shown in most cases between the calcite and the bone ages showing the cave to have been a stable environment for the deposition of bone and the acquisition of uranium

the challenge of direct dating old human fossils abstract this paper reviews the possible approaches for dating of human bones and teeth older than 500 000 years skeletal tissues can in principle be dated with an open system u series approach which requires that the th u activity ratio is still below equilibrium this indicates that the sample experienced continuing u uptake to gain insights about the state of u series isotopes in old samples laser ablation icp ms analysis was used for the detailed mapping of u series isotopes in a 1 2 ma old horse tooth from the archaeological site of fuente nueva iii orce andalusia spain the maps show a complex system of u migration in and out of the dental tissues there are clearly domains in the dentine of the tooth where the th u ratios indicate continuing u accumulation these domains could be extracted and used for open system u series dating firstly the diffusion adsorption model could be applied for open system u series dating of bones well beyond one million years the practical difficulty of this approach is whether there are actually any old samples that conform to the d a model the horse tooth from fuente nueva iii for example was definitely not suitable for d a dating secondly a combination of th u pa u dating could be applied on bones when calculating open system th u pa u isotope evolution diagrams with isochrons it turns out that dating is theoretically possible to perhaps one million years however even the presently most precise analytical results would be associated with errors that will prevent dating beyond about 600 700 ka because the isochrons beyond this time range become very tightly spaced lastly a combination of esr and u series analyses can be used in ideal circumstances for dating teeth up to several millions of years of age

color and albedo heterogeneity of vesta from dawn multispectral images 0 44 to 0 98 m of asteroid 4 vesta obtained by the dawn framing cameras reveal global color variations that uncover and help understand the north south hemispherical dichotomy the signature of deep lithologies excavated during the formation of the rheasilvia basin on the south pole has been preserved on the surface color variations band depth spectral slope and eucrite diogenite abundance clearly correlate with distinct compositional units vesta displays the greatest variation of geometric albedo 0 10 to 0 67 of any asteroid yet observed four distinct color units are recognized that chronicle processes including impact excavation mass wasting and space weathering that shaped the asteroid s surface vesta s color and photometric diversity are indicative of its status as a preserved differentiated protoplanet

the compositional diversity of non vesta basaltic asteroids abstract we present near infrared 0 78 2 45 m reflectance spectra for nine middle and outer main belt a 2 5 au basaltic asteroids three of these objects are spectrally distinct from all classifications in the bus demeo system and could represent spectral end members in the existing taxonomy or be representatives of a new spectral type the remainder of the sample are classified as v or r type all of these asteroids are dynamically detached from the vesta collisional family but are too small to be intact differentiated parent bodies implying that they originated from differentiated planetesimals which have since been destroyed or ejected from the solar system the 1 and 2 m band centers of all objects determined using the modified gaussian model mgm were compared to those of 47 vestoids and fifteen hed meteorites of known composition the heds enabled us to determine formulas relating band 1 and band 2 centers to pyroxene ferrosilite fs compositions using these formulas we present the most comprehensive compositional analysis to date of middle and outer belt basaltic asteroids we also conduct a careful error analysis of the mgm derived band centers for implementation in future analyses the six outer belt v and r type asteroids show more dispersion in parameter space than the vestoids reflecting greater compositional diversity than vesta and its associated bodies the objects analyzed have fs numbers which are on average between five and ten molar percent lower than those of the vestoids however identification and compositional analysis of additional outer belt basaltic asteroids would help to confirm or refute this result given the gradient in oxidation state which existed within the solar nebula these results tentatively suggest that these objects formed at either a different time or location than 4 vesta

230th u burial dating of ostrich eggshell abstract obtaining precise and accurate dates for late quaternary terrestrial sequences containing middle stone age or middle paleolithic archaeological materials ca 30 300 ka can be challenging many such sequences lie beyond the limit of radiocarbon dating 50 ka and lack volcanic ashes suitable for 40ar 39ar dating we report a dating approach with about ten times the range of radiocarbon dating 500 ka based on a novel protocol for 230th u dating of ostrich eggshell a common component of african near eastern and asian archaeological sequences uranium in ostrich eggshell typically at levels of tens to hundreds of ppb is acquired after burial however accurate burial ages can be determined from measured 230th u ages when corrected for uranium uptake via diffusion using ostrich eggshells from a pleistocene holocene east african site we have 1 characterized the spatial distribution of uranium and common thorium 232th concentrations in ostrich eggshell by laser ablation icp ms 2 determined apparent 230th u ages on outer and inner layers of eggshells by solution icp ms analyses of selectively abraded eggshells and 3 calculated 230th u burial ages using a simple model for diffusive uptake of uranium we assess our method by comparing the 230th u burial ages median uncertainty 2 3 1 sd with radiocarbon dates on carbonate from the same eggshells we find good agreement in seven out of nine eggshells confirming the accuracy of their 230th u model ages eggshells that fail to yield reliable 230th u ages may be recognized by anomalous patterns of apparent 230th u ages providing a reliability criterion innate to the 230th u data ostrich eggshells are resistant to diagenesis simplifying 230th u dating compared to bones and teeth eggshells of ostrich emu rhea and other living and extinct ratites found on six continents share similar structure and composition suggesting our new approach to 230th u dating of eggshell may be applicable in diverse late quaternary terrestrial settings

a multi method approach to dating the burial and skeleton of kiacatoo man new south wales australia kiacatoo man a large rugged aboriginal adult buried in the lachlan riverine plains of southeastern australia was discovered in 2011 laser ablation uranium series analysis on bone yielded a minimum age for the burial of 27 4 0 4 ka 2 single grain optically stimulated luminescence ages on quartz sediment in which the grave had been dug gave a weighted mean age of 26 4 1 5 ka 1 luminescence samples from the grave infill and from sediment beneath the grave exhibit overdispersed dose distributions consistent with bioturbation or other disturbance which has obscured the burial signal the overlap between the minimum u series and maximum luminescence ages places the burial between 27 0 and 29 4 ka 2 luminescence ages obtained from the channel belt of between 28 2 and 25 3 ka indicate that fluvial sedimentation was occurring before the last glacial maximum which is consistent with the broader geomorphic setting together these results are internally and regionally consistent and indicate that kiacatoo man was one of the more ancient individuals so far identified in australia his remains are important to our understanding of patterns of biological variation and other processes that have shaped people in the murray darling basin through time

open system modelling for u series and esr dating of teeth abstract the study of the constituents of teeth dentine and enamel by a combination of esr and u series techniques offer unique constraints on the history of uranium migration into these materials our results imply that it is inappropriate to assume a simplified u uptake model for neither the components of a single tooth nor for the faunal remains of a given site however the combination of both methods may provide a new technique for establishing reliable chronologies for archaeological quaternary sites of up to several hundred thousand years

detection of new olivine rich locations on vesta abstract the discovery of olivine on vesta s surface by the vir imaging spectrometer onboard the dawn space mission has forced us to reconsider our views of vestan petrogenetic models olivines were expected to be present in the interior of vesta in the mantle of a vertically layered body as invoked by the magma ocean models or at the base or within the mantle crust boundary as proposed by fractionation models olivines have been detected by vir dawn in two wide areas near arruntia and bellicia regions located in the northern hemisphere interestingly these olivine rich terrains are far from the rheasilvia and the more ancient veneneia basins which are expected to have excavated the crust down to reach the mantle in this work we present our attempts to identify other undetected olivine rich areas on vesta by using spectral parameters sensitive to olivine such as the band area ratio bar and other specific parameters created for the detection of olivines on mars forsterite fayalite and a generic olivine index as a preliminary step we calibrated these parameters by means of vis ir spectra of different hed meteorite samples behaviors versus sample grain size and albedo were analyzed and discussed we selected the bar and the forsterite index as the best parameters that can be used on vesta a cross correlation analysis has been applied in order to detect olivine signature on the vir hyperspectral cubes these detections have then been confirmed by an anti correlation analysis between the bar and one of the olivine parameters independent of the first method applied in agreement with the recent discovery arruntia and bellicia were found to be as the most olivine rich areas i e where the parameter values are strongest in addition we detected 6 new regions all but one located in the vesta north hemisphere this result confirms again that the old petrogenetic models cannot be straightforwardly applied to vesta and should be reshaped in the view of these new detections an alternative and very recent option can be represented by the model according to which surface eruption of material from the mantle including olivine can reach the surface of vesta

new ages for the upper palaeolithic site of xibaimaying in the nihewan basin northern china implications for small tool and microblade industries in north east asia during marine isotope stages 2 and 3 it has been suggested that the small tool and microblade upper palaeolithic industries coexisted in the nihewan basin of northern china for about 8 14 000 years during marine isotope stage mis 2 this inference was based on uranium series ages of around 15 and 18 ka for bovid teeth recovered from the latest small tool site of xibaimaying the youngest occurrence of such tools in the region and optically stimulated luminescence osl dating of the earliest typical microblade site youfang 26 29 ka in this study we re dated the xibaimaying site using single grain osl methods and the resulting ages indicate that the cultural layer was deposited 46 3 ka ago during mis 3 more than 20 millennia earlier than previously thought and older also than the so called earliest primitive and typical microblade tools found at zhiyu 31 39 ka cal bp and youfang these new ages for human occupation of xibaimaying remove support for the parallel development of the small tool and microblade industries in the nihewan basin during the upper palaeolithic but reliable age estimates from additional sites are needed to confidently infer the nature of the chronological relationship between these two upper palaeolithic industries and the associated toolmakers

the challenge of dating early pleistocene fossil teeth by the combined uranium series electron spin resonance method the venta micena palaeontological site orce spain the palaeontological site of venta micena orce andalusia spain lies in the eastern sector of the guadix baza basin one of the best documented areas in europe for plio pleistocene biostratigraphy the combination of biochronological and palaeomagnetic results combined with the radiometric data obtained for atapuerca sima del elefante indicated that the venta micena stratum was formed between the jaramillo and olduvai palaeomagnetic events most likely between 1 22 and 1 77 ma five fossil teeth from two outcrops sites a and b were selected to assess the potential of combined uranium series electron spin resonance us esr dating of early pleistocene sites although the us esr results of the first outcrop showed a large scatter between the three teeth the mean age of 1 37 0 24 ma can be considered a reasonable age estimate for venta micena the mean esr age of 0 62 0 03 ma obtained for site b seems to be a severe underestimation when compared with the independent age control this underestimation is attributed to a relative recent u mobilization event that led to some u leaching the results show that any esr age calculations of old samples are extremely sensitive to variations in the measured 230th 234u ratios in dental tissues although the results demonstrate that esr can in principle be applied to early pleistocene sites they also reveal the complexity of dating such old teeth it is necessary to continue research in several directions such as study of the behaviour of esr signals in old teeth and understanding recent u mobilization processes to improve the reliability of the combined us esr dating method applied to early pleistocene times a period for which the number of available numerical dating techniques is very limited copyright 2011 john wiley sons ltd

successful application of uranium series dating of fossil bone abstract a novel approach to uranium series disequilibrium dating is presented and used successfully to date bones from several european archaeological and palaeontological sites a method is described based on a proposed mechanism of uranium uptake and fixation derived from present understanding of the biochemistry of fossilizing bones and the geochemistry of uranium stability of uranium in fossil bone is predicted under particular conditions of local depositional environment and the importance of the inhomogeneous distribution of uranium through bone to uranium series dating is explained sample bones from several different sites have been examined taking into account the three factors of uptake mechanism uranium distribution and sedimentary environment and have yielded ages in good agreement with those derived by alternative dating methods or from chronologically fixed stratigraphical positions

the timing and cause of megafauna mass deaths at lancefield swamp south eastern australia abstract lancefield swamp south eastern australia was one of the earliest sites to provoke interest in pleistocene faunal extinctions in sahul pleistocene australia new guinea the systematic investigation of the deposit in the early 1970s identified megafaunal remains dominated by the 100 200 kg kangaroo macropus giganteus titan associated radiocarbon ages indicated that the species was extant until c 30 000 bp suggesting significant overlap with human settlement of sahul this evidence was inconsistent with contemporary models of rapid human driven extinctions instead researchers inferred ecological tethering of fauna at lancefield swamp due to intense drought precipitated localised mass deaths consistent with late pleistocene climatic variability later investigations in another part of the swamp the mayne site remote to the initial investigations concluded that mass flow disturbed this area and electron spin resonance esr analyses on megafauna teeth returned wide ranging ages to clarify site formation processes and dating of lancefield swamp we excavated new test pits next to previous trenches in the classic and mayne sites we compared absolute chronologies for sediments and teeth sedimentology palaeo topography taphonomy and macropod age at death across the swamp luminescence dating of sediments and esr analysis of teeth returned ages between c 80 000 and 45 000 years ago we found no archaeological remains in the bone beds and evidence of carnivore activity and fluvial action in the form of reactivated spring flow the latter disturbed limited parts of the site and substantial areas of the bone beds remained intact the faunal assemblage is dominated by megafaunal adult macropus consistent with mass die offs due to severe drought such droughts appear to have recurred over millennia during the climatic variability of marine isotope stages 4 and 3 these events began tens of millennia before the first appearance of aboriginal people in sahul and only the very youngest fossil deposits could be coeval with the earliest human arrivals therefore anthropogenic causes cannot be implicated in most if not all of mass deaths at the site climatic and environmental changes were the main factors in site formation and megafauna deaths at lancefield swamp