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

revised age of the late neogene terror bird titanis in north america during the great american interchange the giant flightless terror bird titanis walleri is known from florida and texas during the late neogene the age of t walleri is problematic because this taxon co occurs with temporally mixed i e time averaged faunas at two key sites thus prior to this study t walleri from the santa fe river florida type locality was either as old as late pliocene ca 2 2 ma or as young as latest pleistocene ca 15 ka likewise t walleri from the nueces river texas was either early pliocene ca 5 ma or latest pleistocene ca 15 ka in order to better resolve this age range the rare earth element ree patterns of t walleri from the santa fe river florida were compared to two biochronologically distinctive groups late pliocene versus late pleistocene of fossil mammals from the same locality similarly the ree patterns of t walleri from texas were compared to two groups early pliocene versus latest pleistocene of fossil mammals from the same locality the ree patterns of t walleri from florida are indistinguishable from those of the co occurring late pliocene mammals likewise the ree pattern of t walleri from texas is indistinguishable from those of the co occurring early pliocene mammals given these ree constraints the revised age of t walleri is early pliocene in texas ca 5 ma and late pliocene ca 2 2 1 8 ma in florida as such t walleri is interpreted as an early immigrant during the great american interchange prior to the formation of the isthmian land bridge no evidence currently exists for pleistocene t walleri in north america

u series dating of fossil teeth and carbonates from snake cave thailand abstract snake cave thailand is an important site for the study of the evolution in southeast asia leading to a discovery of rich and various faunas including a human tooth fossils of large and small mammals converge to indicate on the basis of faunal assemblage a late middle pleistocene age for the fossiliferous layers on the other hand previous u series dating of carbonates furnished a lower limit for the fossils of about 130 ky in order to achieve a better comprehension of the chronology of the cave the uranium series method for absolute age determination has been applied to some carbonates older than those studied previously and to fossils themselves we used the isochron technique approach to yield valuable ages because spleleothem samples consist in a mixture of calcite and detrital contamination the results obtained suggest that the main fossiliferous level is older than about 160 ky the application of the u series method to tooth samples from this tropical cave leads to erroneous ages probably because of post depositional groundwater movements

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

microstructural and geochemical investigations on late cretaceous archosaur teeth from alberta canada microstructural and chemical composition studies on fossil reptile teeth from upper cretaceous localities of alberta canada show that the quality of preservation exhibits great variability within a formation as well as within a locality or even a single tooth the chemical composition of fossil enamel is close to that of modern enamel whereas the chemical compositions of fossil and modern dentine are very different it seems that fossil enamel may have retained some paleodietary information in its chemical composition whereas dentine as well as bone likely did not paleodietary interpretations may thus be drawn from the chemical composition of some elements in tooth enamel such as strontium but more studies on recent reptiles are urged for comparison

stratigraphy of holocene sand shell ridges in the bahia blanca estuary argentina abstract the holocene marine transgression has left important testimonies to itself in the bahia blanca estuary with mainly in the inner part of the estuary set almost parallel to the isohypses between 8 and 10 m sand shell ridges being found these structures are composed of a medium to fine sand with a high percentage of shells 47 species of mollusc radiocarbon dating of the shells in the oldest ridge gave a 14 c age of 4615 110 yrs b p the sand shell ridges present a parallel bedding with slight inclination toward the sea the two ridges studied stand discordantly on clay sandy silt containing laminated and flaser structures these sediments change transitionally with depth to clay silt and silty sand the marine sediments are distributed on a calcrete of late pleistocene age the types of sediments making up the ridges and their stratigraphical relationships are similar to those of cheniers however the term chenier is not used here because the sand shell ridges and their associated deposits have been formed by transgressive regressive sedimentary processes during the latest postglacial

restrictions on fluorine depth profiling for exposure age dating in archaeological bones archaeological fragments of bone and teeth that are exposed to a humid environment take up fluorine from the surrounding soil the fluorine ion replaces the hydroxyl group in the mineral phase of the bone forming chemically more stable fluorapatite in cortical parts of the long bone diaphysis a fluorine concentration profile can be observed which decreases from the outer surface and the marrow cavity towards the inner parts of the bone matrix geological time spans are needed for this process to reach equilibrium and for the distribution to become uniform as the shape of the profile which can be described by a diffusion model contains information on the exposure duration of the fossil object several attempts to use fluorine profiling as a dating method have been undertaken the distribution of fluorine in an archaeological sample however is strongly influenced by environmentally induced processes of bone diagenesis i e alteration in the structure and composition of the mineral phase and degradation of organic components that may make the time information indistinct the primary chemical composition of bones can thus be obscured by diagenesis within tens hundreds or thousands of years this depends more on the diagenetic environment than on the geological age to observe the impact of environmental influence on the profile shape samples from several burial sites featuring various soil conditions have been analyzed for their fluorine distribution and preservation state this paper provides an overview on the restrictions that have to be considered when attempts are undertaken to relate a fluorine diffusion pattern to the archaeological age of a bone specimen

morphodynamics and seismostratigraphy of a deep hole at tidal channel confluence the sedimentary circulation pattern at a deep hole at a tidal channel junction in an estuary environment is examined using morphosedimentological and seismostratigraphic data the bottom and sub bottom acoustic information side scan sonar and 3 5 khz profiler obtained at a tidal channel confluence in bahia blanca estuary argentina evidences the depositional and erosive features bed load sediment transport pathways and morphological evolution of the depression this important depression in the confluence zone of the channels is characterised by the presence of steep scour faces 14 at the mouth of both channels and gentle slopes 1 5 opposite to them bed load sediment transport analysis reveals a differential circulation pattern of sand on both sides of the hole which is associated with the different sediment availability in each channel the side scan sonar information therefore indicates that there is no available sand in one of the channels whereas the other channel is characterised by the presence of a large amount of sediment coming from its inner area deposition therefore occurs on the side where sediment is mobilised as bed load by the ebb current dominance and on the face developed downstream in the latter a part from the sediment is deflected inward by the tidal flood currents which produce the deposition of sediment on the gentle side the rest of the sediment is exported from the system by ebb currents in contrast erosion occurs on the opposite side of the hole and at the mouth of each channel and it is manifested by the outcrop of old sedimentary strata the seismostratigraphic information collected in this study indicates that the depression was originally a fully erosive morphological feature a descriptive model of the morphological evolution at a channel confluence is presented in this study

the structural and diagenetic evolution of injected sandstones examples from the kimmeridgian of ne scotland injected sandstones occurring in the kimmeridgian of ne scotland along the bounding great glen and helmsdale faults formed when basinal fluids moved upward along the fault zones fluidizing oxfordian sands encountered at shallow depth and injecting them into overlying kimmeridgian strata the orientation of dykes in addition to coeval faults and fractures was controlled by a stress state related to dextral strike slip along the bounding fault zones diagenetic studies of cements allow the reconstruction of the fluid flow history the origin of deformation bands in sandstone dykes and sills was related to the contraction of the host rocks against dyke and sill walls following the initial stage of fluidized flow and these deformation bands are the earliest diagenetic imprint early non ferroan calcite precipitated in injection structures at temperatures between 70 and 100 c indicating that it precipitated from relatively hot basinal fluids that drove injection coeval calcite filled fractures show similar temperatures suggesting that relatively hot fluids were responsible for calcite precipitation in any permeable pathway created by dextral simple shear along the faults during progressive burial percolating sea water was responsible for completely cementing the still relatively porous injected sandstones with a second generation of ferroan calcite which contains fluid inclusions with homogenization temperatures below 50 c during this phase depositional host sandstones were also cemented

late quaternary marginal marine deposits and palaeoenvironments from northeastern buenos aires province argentina a review the late quaternary marginal marine deposits along eastern argentina southwestern atlantic are reviewed according to our present knowledge in the northeastern coastal area of buenos aires province they have been assigned to a series of transgressions and regressions ranging from the late pliocene to the late quaternary the most widely accepted model is frenguelli s 1957 classical chronostratigraphical scheme of belgranense late pleistocene marine sediments at 3 6 m above m s l and ca 26 000 35 000 14c years bp the querandinense pleistocene holocene estuarine sediments below or at present m s l and the most extensive platense mid holocene marine deposits at 4 5 2 m above m s l dated at ca 8000 1340 14c years bp the restricted belgranense deposits recorded in samborombon bay in magdalena at ca 32 000 bp near mar chiquita at ca 24 900 and 30 500 bp and southwards in bahia blanca at ca 26 000 35 500 bp may belong to an interstadial gonzalez et al 1986 the molluscan composition suggests a marine invasion of the area but not a typical interglacial cycle characterized by euhaline and warm water elements however the oxygen isotope record argues against an interstadial during the interval 34 27 ka and the chronological control for these deposits is very poor suggesting that they most probably have been elevated neotectonically the pleistocene holocene querandinense deposits extensively distributed along the bonaerensian coastal plain and continental shelf ca 11 000 14c years bp with very low faunal diversity abundance of freshwater ostracods and absence of the warm water molluscs characteristic of the holocene ridges indicate low salinity and cool water conditions further dating and isotope analysis of these deposits are required for a better understanding of the chronology of climatic events by the end of the pleistocene in this area and to establish whether or not they could correspond to the younger dryas event of the northern hemisphere platense littoral ridges formed between ca 7600 and 2500 bp extend in several subparallel rows from ca 34 s to ca 39 s they formed either as beaches or possibly as sublittoral bars in samborombon bay where they reach 120 km long 10 30 m wide and up to 5 m thick at 4 5 5 m above m s l or in the supratidal and intertidal zones in mar chiquita at 2 4 m above m s l molluscs and ostracods suggest a brackish marine to marine brackish environment of lower salinity than the modern atlantic littoral during the mid holocene the oceanic waters were mixing with large amounts of antarctic ice melting in the south atlantic isla 1990 probably reducing salinity along the bonaerensian littoral the oldest littoral ridges accumulated during the hypsithermal and in the punta indio area their different geometry and alignment greatest age highest diversity and warmer affinity of the molluscan fauna suggest a short interval of reversal of the atmospheric circulation pattern further research is necessary for a better understanding of the chronology of the marine late quaternary deposits coastal evolution and climatic changes in this area

geology and geochemistry of bitumen vein deposits at ghost city junggar basin northwest china veins of solid bitumen occur in cretaceous sandstones at the northwest margin of the junggar basin china the bitumen has a low aromaticity and a composition comparable to gilsonite the bitumen contains abundant steranes and terpanes and s carotane although most n and i alkanes have been removed which is characteristic of the local crude oil the sterane and triterpane maturity parameters show that the bitumen local crude oil and source rocks are all mature bitumen wallrock relationships suggest that the host sandstone was not completely consolidated at the time of emplacement of the bitumen veins although bitumen emplacement was a relatively late diagenetic event the burial history for the northwest junggar basin shows that hydrocarbon generation from the assumed upper permian source rocks commenced in late triassic early jurassic times and suggests that rapid hydrocarbon generation may have resulted in overpressure contributing to the bitumen emplacement

problems encountered in the u th dating of fossil red deer jaws bone dentine enamel from lazaret cave a comparative study with early chronological data previous chronological data such as biochronological data u series and electron spin resonance esr data on stalagmitic flowstone e and samples from the sea deposit b are discussed most of these early studies show a deposition of the archaeological levels c during the oxygen isotopic stage 6 for testing the u th dating the method was applied for the first time to the three tissues bone dentine and enamel from fossil cervus elaphus jaws in order to date directly the archaeological levels of lazaret cave twenty seven bones 21 dentine and 17 enamel samples from 30 jaws and two tibias have been analysed by alpha spectrometry the results show a large range of apparent dates with an open system behaviour for the majority of samples the ages range between 50 and 200 ka the main set of data shows that the ages increase upward in the stratigraphic sequence with low values near the base of the sequence the u th apparent ages of dentine are in better agreement with the ages of their respective enamels than with bones the older the u th ages of the bones the larger the uranium content difference between the bone and dentine samples from the same mandible is observed for some samples from all levels of the continental fill a sequence of episodes of uranium isotope leaching and accumulation has resulted in increased uranium isotope ratios and modified uranium content yielding anomalous ages at lazaret cave u th dating on bone and dentine was not successful but data will be used for esr dating

coastal environmental changes associated with holocene sea level fluctuation southeastern buenos aires argentina abstract sea level was 2 m higher than present 6000 years ago at southeastern buenos aires province argentina this fluctuation has caused several environmental changes including drift reversal geomorphological features and radiocarbon dating suggest that the mar chiquita barrier grew from north to south during the regression from 4000 years bp in contrast mineral dispersals coastal defenses inlet migrations and wave statistics show that present beach drift is to the north in the same direction as storm induced shelf sediment transport coastal mollusk mass mortalities lagoonal deposits that accumulated during the regression contain abundant remains of mactra isabelleana tagelus plebeius and labiosa plicatella these species are rare in present coastal lagoons many causes have been proposed for the absence of these species in present lagoons and include sudden sea level decline outlet obstruction producing variation in salinity and increased fluvial freshwater inputs the regional character of these mortalities and growth curves indicates that taphonomic feedback processes related to the scarce 2 m involved in the transgressive regressive cycle are the reason for mollusk mortality sand consumption during the latter stages of the holocene transgression sand ramps up to 10 m height at mar del plata cliffs and sand barriers up to 2 km width north of mar chiquita village developed as a result of high wave energy and a plentiful sand supply the subsequent regressive phase produced lagoons tidal flats marshes and cheniers the alongshore growth of barriers meaned their cannibalization misfit foredunes and narrowing driftwards these processes occurred before the drift reversal mentioned above

the use of soil chemistry data to address post mortem diagenesis in bone mineral abstract the soluble and exchangeable ions for a soil profile from the roonka archaeological site lower murray basin south australia are compared with the total elemental content of the soils since the chemical composition of post mortem ionic substitution phases and secondary minerals in archaeological bone will depend on the availability of ions to the soil solution under field conditions it is suggested that models addressing diagenesis in bone employ soluble and exchangeable ions rather than total elemental soil data

taphonomic processes affecting late quaternary molluscs along the coastal area of buenos aires province argentina southwestern atlantic molluscan concentrations were abundantly deposited along the coastal area of buenos aires province argentina southwestern atlantic by different sea level episodes during the late quaternary most of them represent holocene ridges highly energetic depositional environments subparallel to the modern shore where the main associations preserved are parautochthonous and others mainly autochthonous associations occurring in tidal flats seaward of the ridges or coastal lagoon deposits accumulated behind them low energetic analysis of three physical taphonomic signatures disarticulation fragmentation and abrasion of the molluscan skeletons of four bivalve species tagelus plebeius mactra isabelleana pitar rostratus brachidontes rodriguezi which exhibit different shell shape and thickness conditions habitats and life habits and represent the most widely distributed and palaeoecologically significant taxa along the area of study support the distinction of both palaeoenvironments characterized by low and high taphonomic grades respectively the taphonomic alteration breakage and abrasion of most shells seems to have been a direct consequence of the amount of reworking of the material especially during periods of exposure along an extensive beach zone more than a consequence of transport from a distant original habitat abrasion signatures are the only probably correlated with after death time span shells showing a near modern aspect and original luster being most probably younger than those with chalky or polished appearance the infaunal species analysed typically living on clays and silts or fine sandy bottoms of the infralittoral or intertidal t plebeius m isabelleana are better preserved less fragmented and abraded than shells of the epibyssate b rodriguezi which lives on hard bottoms of the intertidal and supralittoral areas more exposed to highly unstable conditions with longer episodes of exposure although these nearshore concentrations may represent a time averaging of 1000 yr b p taking into account the ecological requirements of the most constant and dominant taxa together with the taphonomic analysis of shells from parautochthonous and autochthonous associations they still represent valid indicators of past marginal marine conditions in the area but are only reliable to establish long term palaeoenvironmental variations

can fossil bones and teeth be dated using fission track analysis the high proportion of crystallized apatite forming the bones and teeth should theoretically allow the use of fission track analysis to date vertebrate fossils when burying of the fossiliferous series did not subject them to temperatures exceeding 60 degrees c however several major obstacles arise such as the complexity of fossils internal structures diagenetic modifications and substitutions of the hydroxyapatite by other minerals and massive u uptake or loss during diagenesis in this work those various problems are addressed combining optical microscope observation of the fossils a systematic fission track analysis of the best samples alpha and gamma spectrometry and secondary ion mass spectrometry even if the problems caused by internal structures and mineral substitutions can be solved u movements in and out of the fossils are generally too complex to allow fission track analysis dating of the fossils

expanding the utility of uranium series dating of speleothems for archaeological and palaeontological applications uranium series u series dating of speleothems is frequently used for palaeoclimate studies but its archaeological and palaeontological applications are limited to stratigraphically significant speleothem formations such as flowstones to provide maximum and minimum temporal points this study targeted soda straw stalactites for u series dating in contrast to other speleothem formations soda straw stalactites are fragile have typically short life spans usually only years but rarely up to a few hundred years and are frequently incorporated into cave deposits results of thermal ionisation mass spectrometry tims u series dating of soda straw stalactites from palaeontological excavations at blanche cave south australia show that small dense clean straws tend to yield ages closest to the time of stratigraphic deposition a correlation between soda straw u series ages and radiocarbon ages of charcoal from the site is shown multiple soda straw age determinations for a single stratigraphic unit are required in order to verify age concordance in conjunction with other dating methods u series dating of soda straw stalactites may help to significantly constrain the age of stratigraphic units and associated archaeological and palaeontological deposits in order to provide more robust chronologies here we advocate the collection of soda straw stalactites at future excavations of limestone cave sites

the environment of deposition indicated by the distribution of rare earth elements in fossil bones from olduvai gorge tanzania fossil bones of pleistocene age from olduvai gorge tanzania incorporated relatively high concentrations up to several thousands ppm of rare earth elements during their fossilization the data indicate that these elements were mobile during the diagenetic processes involved in the fossilization of the bones it is suggested that the high concentrations arose through interaction of the bone with groundwaters enriched in these and other elements introduced by contemporaneous carbonatitic or alkalic volcanism the distributions of the rare earth elements within both the fossil bone and enclosing sediment are heterogeneous but spatially systematic with concentration profiles showing a maximum in the bone at its sediment interface despite the relative porous nature of bone the steepness and variability of the rare earth element profiles indicate chemical equilibrium has not been reached of the individual rare earth elements ce behaved differently from the others systematic variations in and magnitudes of the ce anomaly within the bone cortices from different depositional environments indicate that the redox potential of the environment during fossilization was the principal factor affecting the distribution of this element

uranium and thorium in fossil bones activity ratios and dating we have analysed fossil bones by u series disequilibrium from five different sites ngandong and sonde indonesia gold ox hill people s republic of china pestera romania and ksar akil lebanon two samples were taken from all bones one representing surface material and one from the inner bone bulk material in general the u concentration at the surface was found to be lower than in the bulk resulting in higher ages this might be explained by leaching of u from the surface area of the bone which means that the surface material of the bones cannot be considered to be a closed system an exception is the gold ox hill series where we found that the u concentration is roughly constant throughout the bone also the ages are roughly the same for surface and bulk material in this case

mixed marine and lacustrine input to an oil cemented sandstone breccia from brora scotland abstract a rounded cobble collected from a beach near brora scotland contains angular brecciated sandstone clasts cemented together by crude oil no oil occurs within the tight dolomite cemented clasts except along fractures provenance of the cobble is uncertain however the lithology and shape of the clasts suggests that they are fault gouge breccia composed of old red sandstone from the nearby helmsdale fault oil emplacement presumably along the fault cemented the breccia prior to transport and weathering of the cobble independent source and biodegradation parameters support mixing of two charges of oil like oil from the nearby beatrice field the oil cement contains 24 n propylcholestanes and carotane that indicate marine and lacustrine source rocks respectively the oil cement also contains pristane phytane residual n alkanes and a complete series of 25 norhopanes which indicate mild and heavy biodegradation respectively the first charge consisted of lacustrine devonian oil that was heavily biodegraded at shallow depth the origin of the second charge is unclear unlike beatrice oil the oil cement contains oleanane and shows a higher 24 24 27 nordiacholestane ratio suggesting input from a cretaceous or younger paralic marine shale source rock although cretaceous and paleocene source rocks are inferred to exist in various depocenters in the northeast atlantic margin subcrops of these rocks offshore brora are thermally immature alternately the second charge could originate from an effective middle jurassic source rock that contains oleanane this hypothesis is supported by mass spectrometric confirmation of oleanane in an extract from the marine equivalent of the middle jurassic brora coal in the nearby ukcs 11 30 2 well oleanane in crude oil is not positive proof of a cretaceous or younger source rock for the oil

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

isotope compositions c o sr nd of vertebrate fossils from the middle eocene oil shale of messel germany implications for their taphonomy and palaeoenvironment abstract the middle eocene oil shale deposits of messel are famous for their exceptionally well preserved articulated 47 myr old vertebrate fossils that often still display soft tissue preservation the isotopic compositions o c sr nd were analysed from skeletal remains of messel s terrestrial and aquatic vertebrates to determine the condition of geochemical preservation authigenic phosphate minerals and siderite were also analysed to characterise the isotope compositions of diagenetic phases in messel diagenetic end member values of the volcanically influenced and due to methanogenesis 12 c depleted anoxic bottom water of the meromictic eocene maar lake are isotopically very distinct from in vivo bioapatite values of terrestrial vertebrates this unique taphonomic setting allows the assessment of the geochemical preservation of the vertebrate fossils a combined multi isotope approach demonstrates that enamel of fossil vertebrates from messel is geochemically exceptionally well preserved and still contains near in vivo c o sr and possibly even nd isotope compositions while bone and dentine are diagenetically altered enamel of the hippomorph perissodactyl propalaeotherium has low 13 c values 9 0 7 typical for c 3 plant feeders dentine of the same teeth has 13 c values 15 17 higher amongst the highest 13 c bioapatite values reported for terrestrial vertebrates this reflects diagenetic carbonate exchange with the strongly 12 c depleted anoxic lake bottom water enamel 87 sr 86 sr values 0 711 0 001 are consistent with propalaeotherium feeding on palaeozoic bedrocks surrounding lake messel and suggests that the basaltic tuff ring around the maar was already eroded 640 ka after its formation dentine has however much lower volcanically influenced 87 sr 86 sr 0 706 due to diagenetic sr uptake from the lake water oil shale enamel 18 o p values 18 0 6 of propalaeotherium are 2 3 lower than those of bones and scales of aquatic vertebrates that lived in the 18 o enriched lake water using transfer functions a 18 o h 2 o value of 5 1 for meteoric water and a mat of 18 2 5 c were reconstructed for messel

subsurface biodegradation of crude oil in a fractured basement reservoir shropshire uk subsurface biodegradation of crude oil in current oil reservoirs is well established but there are few examples of ancient subsurface degradation biomarker compositions of viscous and solid oil residues bitumen in fractured precambrian and other basement rocks below the carboniferous cover in shropshire uk show that they are variably biodegraded high levels of 25 norhopanes imply that degradation occurred in the subsurface lower levels of 25 norhopanes occur in active seepages liquid oil trapped in fluid inclusions in mineral veins in the fractured basement confirms that the oil was emplaced fresh before subsurface degradation a triassic age for the veins implies a 200 myr history of hydrocarbon migration in the basement rocks the data record microbial biodegradation of hydrocarbons in a fractured basement reservoir and add to evidence in modern basement aquifers for microbial activity in deep fracture systems buried basement highs may be especially favourable to colonization through channelling fluid flow to shallow depths and relatively low temperatures and are therefore an important habitat within the deep biosphere

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

u series dating and human evolution some of the major events in human evolution occurred during the middle pleistocene these include the evolutionary rise of the neanderthals in eurasia and of anatomically modern humans either in africa or on a broader geographical front in addition to major biogeographic changes among mammals including the hominine colonization of europe prior to the middle pleistocene the application of potassium argon and argon argon dating has yielded a relatively detailed chronological picture for the earlier phases of hominid evolution and from c 50 ky radiocarbon dating provides the backbone of our chronology for the extinction of the neanderthals colonization of europe by anatomically modern humans and all subsequent events between these however the middle pleistocene has only been amenable to precise chronometric dating for the past few decades before the advent of radiometric dating as glynn isaac 1975 famously observed the middle pleistocene was the muddle in the middle u series dating is one of a range of dating methods employed by archaeologists to provide a chronology for human evolution fig 1 other applicable methods include optically stimulated luminescence osl which can be used to date sediments perhaps back to about 0 5 my measuring the time since the last exposure to sunlight it is increasingly employed as a dating method especially since suitable sediments are common on archaeological sites e g aitken 1992 a related technique thermoluminescence tl can be used to date burnt flint artifacts e g aitken 1985 which provide a more direct date for specific human activity on a site although material that is suitably burnt is relatively rare potassium argon and argon argon dating have been the most useful techniques for calibrating early hominid evolution because its limit for dating extends considerably beyond the origins of the earliest hominids at around 5 my e g curtis and hay 1972 their application however is

mass mortality of a holocenetagelus plebeius mollusca bivalvia population in the bahia blanca estuary argentina abstract a mass mortality phenomenon affecting a mollusc fauna on the holocene tidal flat of the bahia blanca estuary is analyzed specimens oftagelus plebeius are located in a well defined horizon with both valves articulated and in life position the mass mortality of thetagelus plebeius population is a consequence of its catastrophic burial by sandy sediment of fluvial origin

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

shale tectonics and deformation associated with active diapirism the jerudong anticline brunei darussalam the jerudong anticline provides an outcrop example of multiple phases of diapir growth and interaction with the country rock the n s trending anticline overlies a high angled basement fault zone that was episodically active moving predominantly sinistrally in response to transpressive stresses the earliest stage of deformation in the study area was mid miocene e w to ne sw trending growth faulting and shale diapir growth early normal faults exerted an important influence on the large and small scale bedding geometries and facies changes of syn tectonic shallow marine shoreface and tidal strata in particular there are laterally rapid facies changes and differential rotation of strata across growth faults diapir activity is indicated by the presence of shale dykes which commonly intrude normal fault planes and concordant shale intrusions shale intrusions associated minor thrust faults and normal faults were rotated during a late miocene early pliocene phase of folding related to transpression few shale dykes were intruded during this phase probably because the horizontal principal stresses were relatively large compared with the pore fluid pressure at the end of the transpressive phase shale dykes were intruded into steeply dipping beds as a result of stress relaxation continued uplift and erosion elevated overpressured horizons to a point where hydraulic fracturing reached the surface and holocene age mud volcanoes were developed

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

trace elements and their isotopes in bones and teeth diet environments diagenesis and dating of archeological and paleontological samples fossil biogenic apatites display trace element te compositions that can record environmental and biological signals give insights into past water compositions or be used for dating paleontological and archeological bones and teeth processes of te incorporation into apatites of skeletal phosphatic tissues are described ranging from those active in living organisms to those active during diagenesis abiotic incorporation mechanisms have been modeled theoretically and experimentally and include crystallographic controls on te partitioning coefficients inorganic surface adsorption and adsorption mediated through chelation and diffusion adsorption processes each leading to specific fractionation patterns predictions from models and experiments have been tested against te concentration and isotopic composition data on remains of contemporary wild or raised animals and on fossils of various ages and environments in living organisms tes incorporated in apatite are separated in two categories non essential elements whose concentration is compared to that of an essential element with similar behavior e g sr ca to reconstruct trophic chains and essential elements whose isotopic ratios are used to trace metabolic activity diet etc in fossils elements are incorporated during diagenesis such as rare earth elements rees and trace diagenetic processes ranging from very early quantitative adsorption likely mediated by chelators protracted diagenesis through inorganic adsorption and fractionation through diffusion adsorption to low grade metamorphism associated with intense redistribution under crystal chemical control these different steps are also identified as steps of radionuclide incorporation only samples where the earliest steps can be deciphered are useful for determining stratigraphic and archeological ages other samples will date late diagenetic events that have obliterated the paleoenvironmental signals but may be of geological significance e g tectonic events

mass spectrometric u series dating of new cave at zhoukoudian china abstract we report here mass spectrometric u series dates on calcite samples from new cave one of the zhoukoudian localities the lowermost sub layer of the capping flowstone dates to ca 120 ka implying the absence of late pleistocene cultural deposits within the cave the second flowstone layer was formed between 248 and 269 ka marking possibly the minimum age of the hominid fossil three samples taken from the lowest accessible strata date to ca 300 ka suggesting an even greater antiquity for the cultural horizon at the bottom of the depositional sequence the new age assignment from previously estimated early late pleistocene to late middle pleistocene makes new cave broadly contemporaneous with the uppermost strata of the peking man site this is in line not only with the observation that the previously established chronological sequence for chinese middle late pleistocene sites may have been underestimated as a whole but also with the hypothesis that human occupation of the zhoukoudian sites has been more or less continuous over hundreds of thousand years

25 norhopanes formation during biodegradation of petroleum in the subsurface abstract quantitative data from petroleum systems in china liaohe basin and canada athabasca tar sands support the theory that 25 norhopanes are produced during biodegradation of petroleum in the subsurface within a single oil column both case histories showed increasing severity of degradation indicated by destruction of hopanes and production of 25 norhopanes downward to the oil water contact in the athabasca samples between the peters k e moldowan j m 1993 the biomarker guide interpreting molecular fossils in petroleum and ancient sediments prentice hall englewood cliffs new jersey p 363 scale of biodegradation levels 5 9 concentrations of c 28 20s triaromatic steroids and other biodegradation resistant compounds increased by 35 reflecting a concentration effect as a consequence of removal of more degradable compounds over the same interval the concentrations of c 28 17 25 norhopane and c 29 17 25 norhopane increased by an order of magnitude thus requiring that the balance be met by their net production during degradation a detailed molecular investigation of the athabasca bitumen revealed that c 30 17 hopane degrades faster than c 29 17 hopane whilst the rate of formation of both c 29 17 25 norhopane and c 28 17 25 norhopane are similar complicating a straightforward interpretation of demethylation of hopanes to form 25 norhopanes hopane degradation in the athabasca tar sand may also occur without the production of 25 norhopanes the results show that even within a single petroleum accumulation a number of mechanisms control changes in the abundance and composition of hopanes and 25 norhopanes

protracted diagenetic alteration of ree contents in fossil bioapatites direct evidence from lu hf isotope systematics abstract fossil bones and teeth are potentially important repository for geochemical proxy data and a target for radiometric dating the concentration of many trace elements in bones and teeth increases by orders of magnitude after death and it is this diagenetic incorporation that forms the basis for several areas of geochemical study the use of bones and teeth in this context relies on two assumptions first that target metal ions are incorporated rapidly after death reflecting a known environmental signal and second that after early incorporation the bone or tooth remains as an essentially closed system resistant to later diagenetic change a wide literature has developed exploring these assumptions but relatively little direct evidence has been used to assess the long term diagenetic stability of trace elements within bones and teeth in this study we use the lu hf isotope system to show that bones and teeth of cretaceous and triassic age from both terrestrial and marine settings experience continued long term diagenetic change most likely through gradual addition of trace elements modelling suggests that diagenetic addition after initial recrystallisation may account for 50 of the total ree content in the sampled bones the extent depending on initial uptake conditions tooth enamel and enameloid may be more resistant to late diagenetic changes but dentine is probably altered to the same extent as bone these results have significant implications for the use of bones and teeth as hosts of chronological palaeoceanographic palaeoenvironmental and taphonomic information particularly in mesozoic and palaeozoic contexts

lacustrine organic facies a biomarker study using multivariate statistical analysis abstract four distinct depositional settings in the devonian orcadian basin of scotland have been characterised by their minerology and organic geochemistry with the help of multivariate statistical analysis the data visualise the organic matter source input the depositional environment and the level of thermal maturity principal component analysis proved invaluable for extracting information from a data set composed of a large number of parameters the thermal maturity of the majority of the samples lies within a restricted range in the oil window and biomarker composition reflects predominantly organic input and depositional environment basin margin deposits are clearly differentiated from deeper water central lake deposits salinity and anoxicity variations are seen within the latter type of deposits

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

new structural and re os geochronological evidence constraining the age of faulting and associated mineralization in the devonian orcadian basin scotland the devonian orcadian basin in northern scotland belongs to a regionally linked system of post caledonian continental basins extending northwards to western norway and eastern greenland extensional fault systems that cut the orcadian basin sequences are commonly assumed to be devonian with some limited inversion and reactivation proposed during the carboniferous and later times we present a detailed structural study of the regionally recognized fault systems exposed in the dounreay area of caithness which host significant amounts of authigenic mineralization carbonate base metal sulphides bitumen structural and microstructural analyses combined with re os geochronology have been used to date syndeformational fault infills pyrite suggesting that faulting brecciation and fluid flow events are likely to have occurred during the permian 267 5 3 4 3 5 ma stress inversion of fault slickenline data associated with mineralization suggest nw se regional rifting an episode also recognized farther west in sutherland thus a dominant set of permian age brittle faults is now recognized along the entire north coast of scotland forming part of the regional scale north coast transfer zone located on the southern margin of the offshore west orkney basin supplementary material onshore and offshore fault and fracture lineament data are available at https doi org 10 6084 m9 figshare c 2182433

emplacement of bitumen asphaltite veins in the neuquen basin argentina veins of solid bitumen asphaltite have been commercially exploited in the neuquen basin argentina for over 100 yr veins are up to 5 m wide and several kilometers in length over a region of 15 000 km2 these veins were emplaced in fractures both parallel and at high angles to bedding in close proximity to their source rocks in the vaca muerta and agrio formations late jurassic early cretaceous two or more phases of bitumen emplacement can be recognized in several localities structures bearing viscous oil are younger than structures having solid bitumen bitumen emplacement was vigorous and caused brecciation and spalling of the host rocks the bitumen was also viscous and supports rock debris ranging in size from sand grains up to meter scale slabs brecciation bedding parallel injection and wall rock impregnation suggest high fluid pressures during emplacement high fluid pressure may have been engendered by substantial hydrocarbon generation from rich source rocks in a low permeability sequence and probably caused the fractures into which the bitumen migrated the bedding parallel veins facilitated decollement during thrusting that took place during and after bitumen emplacement the timing of emplacement relative to thrusting and oil migration constrains bitumen emplacement to the eocene oligocene

mechanisms and controls on the formation of sand intrusions sandstone intrusions are found in all sedimentary environments but have been reported most commonly from deep water settings they also appear to be more frequently developed in tectonically active settings where applied tectonic stresses facilitate development of high fluid pressures within the sediments a variety of mechanisms have been cited as triggers for clastic intrusions these include seismicity induced liquefaction application of tectonic stresses excess pore fluid pressures generated by deposition related processes and the influx of an overpressured fluid from deeper within the basin into a shallow sand body the formation of sandstone dykes and sills is investigated here by considering them as natural hydraulic fractures when the seal on an unconsolidated overpressured sand body fails the resulting steep hydraulic gradient may cause the sand to fluidize the fluidized slurry can then inject along pre existing or new fractures to form clastic intrusions the scale and the geometry of an intrusive complex is governed by the stress state depth and pre existing joints or faults within the sedimentary succession as well as the nature of the host sediments for the simplest tectonic setting where the maximum stress in a basin is vertical gravitational loading small irregular intrusions commonly result in the formation of sills at shallow depths within a few metres of the surface whereas at greater depth dykes and sills forming clastic intrusion networks are more typical a simple relationship is derived to calculate the maximum burial depth at which a dyke sill complex forms as a function of the source bed to sill height the bulk density of the surrounding sediments and the ratio of the vertical to horizontal effective stresses k 0 when applied to three examples of large scale dyke sill complexes developed within paleocene and eocene deep water reservoir sand bodies of the north sea maximum burial depths in a range of 375 to c 500 m 450 700 m and 550 850 m are estimated for intrusion of each of the three complexes

origin of beatrice oil by co sourcing from devonian and middle jurassic source rocks inner moray firth united kingdom commercial hydrocarbons in the moray firth area of the north sea occur in reservoirs ranging in age from devonian to tertiary with the bulk of the reserves located in upper jurassic and lower cretaceous clastic rocks most hydrocarbon discoveries in this area have been made in the outer moray firth primarily in the witch ground graben a single oil field beatrice has been developed in the inner moray firth area the unusual location and chemical composition of beatrice compared to piper and other north sea oils generated from the kimmeridge clay have contributed to the longstanding controversy on its origin oil source potential in the inner moray firth has been recognized in lacustrine devonian dolomitic siltstones middle jurassic paralic coals upper jurassic marine shales and other rocks however prior to this study only the upper jurassic kimmeridge clay was recognized as a significant effective source rock in the main graben area of the north sea biomarker and stable carbon isotope analyses conclusively show that beatrice oil could not have been generated from the classic kimmeridge clay source rock but is a mixture of products derived from effective devonian and middle jurassic source rocks this work demonstrates the power of a multiparameter geochemical approach in solving this difficult oil to source rock correlation problem use of this approach can lead to the recognition of new exploration plays in previously well explored basins

the recognition of multiple hydrocarbon generation episodes an example from devonian lacustrine sedimentary rocks in the inner moray firth scotland burmah well 12 27 1 drilled on a structural high in the inner moray firth penetrated over 3000 ft 914 m of lower devonian organic rich sedimentary rocks these have been analysed for source rock potential and contain a substantial proportion of oil prone thermally mature kerogen a decompacted vitrinite reflectivity profile shows that the lower part of the devonian section has a steeper thermal maturity gradient which is interpreted as indicating a high devonian geothermal gradient associated with basin extension solid bitumen reflectivities and organic petrography show that the most recent hydrocarbon generation occurred in the upper part of the devonian interval during maximum tertiary burial vitrinite reflectivity data from the jurassic rocks in the beatrice field and onshore east sutherland enable the position of the oil generation window to be predicted in relation to the depth of the top of the devonian sequence the main controls on devonian source rock potential in the inner moray firth are not the depth of mesozoic and tertiary burial but the distribution of source rocks their degree of permian truncation and the pre permian thermal maturity level

origin of organic matter from tectonic zones in the western tatra mountains crystalline basement poland an example of bitumen source rock correlation abstract solid bitumens of unknown origin found in brittle tectonic shear zones cutting the crystalline basement of the western tatra mts show uniform geochemical characteristics that suggest a uniform source for the original hydrocarbons on the basis of gc ms data a similarity between these solid bitumens and organic matter dispersed in the mesozoic source rocks of podhale trough and sedimentary cover of the northern tatra mts is observed the organic matter in the mesozoic source rocks shows a higher maturation level than that in the solid bitumens the molecular composition of the organic matter in both the solid bitumens and the basement rocks is significantly different from that in the paleogene sedimentary rocks infilling the podhale trough these immature to early mature paleogene sedimentary rocks contain organic compounds typical of terrestrial plants both conifers simonellite and retene and angiosperms lupane oleanane and taraxastene which are absent in the solid bitumens and in the mesozoic source rocks water co2 fluid inclusions in quartz sealing the shear zones have marine like salinity a dominance of cacl2 and mg2 depletion suggesting genetic affinity to dolomitised carbonate rocks such as potential middle triassic source rocks the low maturity of the solid bitumen in the shear zones relative to its mesozoic source can be explained by continued maturation of the mesozoic source rocks after expulsion and migration into the shear zones the results of hydrocarbon generation modeling indicate that oil expulsion from the mesozoic source rocks its migration through the shear zones and the subsequent maturation of the mesozoic source rocks all occurred within a short oligocene time interval

constraining causes of fish mass mortality using ultra high resolution biomarker measurement lamina by lamina measurement of biomarkers at a sub millimetre resolution within the achanarras limestone member has helped to resolve the changing environmental conditions associated with a fish mass mortality horizon an anomalous proportion of c30 sterane 24 n propylcholestane marks the beginning of the horizon and likely corresponds to an influx of marine water this appears to have been short lived and was likely analogous to a modern day storm tide the subsequent laminae record an increased incidence of water column stratification and hypoxic bottom waters in the form of an elevated gammacerane index the mass mortality horizon studied was from an upper interval of the achanarras limestone member with a fossil fish assemblage comprising mostly dipterus an early dipnoan lungfish however lower intervals of the achanarras limestone member have greater assemblage diversity including species associated with marine conditions such as coccosteus and evidence higher proportions of c30 sterane indicating better connection to the marine environment therefore it appears that ingressing seawater in and of itself was not responsible for creating a stressed environment rather disconnection of the lake from marine waters stranded fish in a lake that when perturbed by storm tides killed en masse by exposing fish to hypoxic conditions in a similar way to modern water bodies affected by storm tides generated during hurricanes

quantification of diagenesis in cenozoic sharks elemental and mineralogical changes abstract diagenesis of bone during fossilization is pervasive however the extent of this process varies with depositional environment this study quantifies diagenesis of shark vertebral centra through analysis of a suite of physical and chemical characters including crystallinty index ci carbonate content and elemental concentrations although shark skeletons are initially cartilaginous the soft cartilage of the vertebral centra is replaced with carbonate hydroxyapatite during growth nine vertebral centra are analyzed from lamnoid lamnoidea sharks ranging in age from the cretaceous to recent using fourier transform infrared spectroscopy ft ir and inductively coupled plasma mass spectrometry icpms the variables ci carbonate content rare earth element ree concentrations ca p ba ca sr ba la yb n la y n la yb n vs la sm n la yb and ce anomalies elucidate the diagenetic and depositional environments of the seven fossil vertebral centra the two extant centra demonstrate the initial unaltered end member conditions for these variables two fossil vertebral centra carcharodon megalodon and isurus hastalis demonstrate a strong terrestrial influence during diagenesis distinctive flattening of shale normalized ree patterns that masked the seawater signal three centra carcharodon auriculatus carcharodon angustidens and creotxyrhina mantelli have indications of some terrestrial influx evident by some flattening of the ree patterns relative to seawater the terrestrial influence in these five shark centra c megalodon i hastalis c auriculatus c angustidens and c mantelli are interpreted to represent a primarily nearshore habitat for these species in contrast the two otodus obliquus centra have ree patterns that represent the original seawater signal and have no indications of terrigenous input these results indicate that fossil shark vertebral centra have the potential to understand diagenesis and reconstruct paleooceanographic environments

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

detailed mass spectrometric u series analyses of two teeth from the archaeological site of pech de l aze ii implications for uranium migration and dating abstract we report th u ages obtained by thermal ionization mass spectrometry of cross sections of two teeth from the archaeological site of pech de l aze ii the aim of this study is to reconstruct the pathways and time dependency of uranium uptake into different constituents of the two teeth a previous esr dating study of the two teeth yielded age estimates in the range of about 130 000 to 200 000 years which was in agreement with the geological assignment of riss for layers from which the specimens were recovered the closed system u series ages of all analyses range from 48 to 137 ka thus yielding age estimates which are between 30 and 90 ka too young the apparent closed system u series ages of the dentine and cement fractions at the top of the teeth are the oldest becoming gradually younger towards the interior of the two teeth the difference between apparent u series ages of dentine at the outer and inner parts of the two teeth is about 35 ka the enamel sections show the same patterns in u concentration and progression of apparent th u ages as the adjacent dentine samples but with generally younger ages our results indicate that uranium migrates both from the top and the base into the dentine of the teeth and from there into the adjacent enamel depending on the position of the sample significant uranium uptake appears to have taken place over many tens of thousands of years modelling the u uptake histories using a parametric model shows that for the cement and dentine components uptake is intermediate between linear uptake lu and early uptake eu closed system the enamel although often assumed to approximate more closely a closed system shows evidence of more recent u uptake these results also imply that it is not possible to use a simple single parameter u uptake model for all components of a given tooth either for u series or esr dating

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

geochemistry and origin of organic rich sediment veins in fractured granitic basement helmsdale sutherlandshire uk abstract black sediment veins up to 2 cm width penetrate the caledonian helmsdale granite in the vicinity of the helmsdale fault onshore moray firth the black colour and geochemistry of the veins reflect a high content of organic carbon both devonian and jurassic shales are conceivable available sources but sterane compositions relate the organic matter to the jurassic shales a content of extractable organic matter higher than in the shales suggests that the carbon in the veins represents oil rather than mechanically mobilized shale the oil was present during sediment vein emplacement the veins were emplaced forcefully which may reflect high fluid pressure associated with post jurassic movement on the helmsdale fault

u series dating and taphonomy of quaternary vertebrates from brazilian caves abstract the geochronology and taphonomy of internationally important fossil bearing cave deposits were studied both in the semi arid northern bahia area and the subtropical southeastern lagoa santa area of brazil taphonomic analysis suggests that the processes responsible for bone accumulation in the brazilian caves vary between sites and taphonomic bias can therefore be significant in causing differences in faunal composition in the toca da boa vista caves the presence of single articulated skeletons and the entrance related distribution indicate that random penetration of animals is the main mechanism of fossil accumulation a process that biases the assemblage to smaller species and takes place over extended time periods in nearby toca dos ossos cave transport by runoff in the cave river is predominant and biases the fauna remains to larger more robust bones and species deposition probably also occurred only at times of enhanced runoff giving a more contemporaneous assemblage similar processes were responsible for emplacement of the copious fossil remains in the more humid lagoa santa area where terrigenous fossil deposits are found intercalated by massive speleothem calcite layers in this area runoff under a drier climate probably accounts for the sediment emplacement inside caves in both areas the mode of emplacement implies bias in the fossil record resulting in fossil assemblages that do not mirror surface faunas limiting palaeoenvironmental reconstruction mass spectrometric u series analysis of speleothem calcite overlaying fossil remains gives minimum ages for fossil deposition these ages confirm the previous view that many of the deposits derive from the late glacial but also show that much older material some 350 000 yr is also present the habitat requirements of critical fossil species such as bats and monkeys strongly suggest that they derive from much wetter periods when forest cover was present in the currently semi arid northern bahia area taphonomy exerts a major control on the diversity and mode of emplacement of cave fossil deposits in eastern brazil and thus detailed sedimentological and hydrological studies coupled with a sound geochronological approach are essential in quantifying the relative importance of each taphonomic processes before faunal and palaeoecological interpretations can be attempted

mass spectrometric u series dating of the chaoxian hominin site at yinshan eastern china the fossils of chaoxian hominin widely accepted as representing archaic homo sapiens in eastern china were recovered from the middle or slightly higher levels of layer 2 deposits of a collapsed cave at yinshan anhui province results of mass spectrometric u series dating of intercalated speleothem calcites are presented based mainly on four broadly coeval calcite samples the hominin fossils should be bracketed in the range of 310 360 ka or somewhat older these ages are much older than the previous estimate at 160 200 ka based on the u series dating of fossil teeth and bones and may be cited as supporting evidence for an earlier h erecrus archaic h sapiens interface in china c 2009 elsevier ltd and inqua all rights reserved

palaeoecology and sedimentology across a jurassic fault scarp ne scotland a detailed palaeoecological and sedimentological analysis of the kimmeridgian coastal outcrops around helmsdale northeast scotland has been related for the first time to a detailed biostratigraphical scheme allowing the depositional history of this important area adjacent to some north sea oilfields to be elucidated a broad shallow marine sub tropical shelf was disrupted by the onset of normal faulting along the helmsdale fault in earliest kimmeridgian times initially water depths remained shallow on the hanging wall reflected by a normal benthic fauna but a rapidly steepening southeast directed palaeoslope produced frequent sediment sliding shoreface sands developed immediately to the west of the fault and were transferred to the hanging wall via a fault transfer zone where they now constitute the allt na cuile formation continued rapid subsidence during the remainder of the kimmeridgian and the portlandian produced deep poorly oxygenated to anoxic benthic conditions on the hanging wall in which a combination of rock slide debris flow turbidity current deposition alternated with hemipelagite deposition to produce the helmsdale boulder bed formation the eathie locality cromarty previously regarded as a deeper more distal setting than helmsdale contains a slightly more diverse benthic fauna implying shallower water the deepest waters were immediately adjacent to the fault scarp as predicted by the standard half graben depositional model

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

rare earth element composition of paleogene vertebrate fossils from toadstool geologic park nebraska usa fossil bones and teeth from terrestrial environments encode unique rare earth and trace element ree and te signatures as a function of redox conditions ph concentrations of complexing ligands and water colloid interactions this signature is set early in the fossilization process and serves as a paleoenvironmental and paleoclimatic proxy these signatures can also be used to interpret temporal and spatial averaging within vertebrate accumulations and can help relocate displaced fossil bones back into stratigraphic context rare earth elements in vertebrate fossils from upper eocene and oligocene strata of toadstool geologic park northwestern nebraska record mixing and evolution of paleogene vadose or groundwaters and variations in paleoenvironments ree signatures indicate that hree enriched alkaline groundwater reacted with lree and mree enriched sediments to produce 3 component mixtures ree signatures become increasingly lree and mree enriched toward the top of the studied section as the paleoenvironment became cooler and drier suggesting that ree signatures may be climate proxies time series analysis suggests that ree ratios are influenced by cycles of ca 1050 800 570 440 and 225 ka similar to some previously determined milankovitch astronomical and climate periodicities

elemental composition and diagenetic alteration of dinosaur bone distinguishing micron scale spatial and compositional heterogeneity using pixe abstract proton induced x ray emission pixe analysis of thirteen late cretaceous hadrosaurid tyrannosaurid and tyrannosaurus and early jurassic dilophosaurus dinosaur bones two late cretaceous crocodylians one plesiosaur and three modern archosaurs rhea and caiman documents micron scale diagenetic patterns of elemental uptake and loss pixe detected al si p s cl k ca ba mn fe sr y and nd at levels 1000 ppm and ti cr ni zn as zr and u at trace amounts 100 of modern this enrichment may reflect the migration of ca and p between the hydroxylapatite matrix and the surrounding sediment after death resulting in early diagenetic loss followed by uptake and recrystallization on crystallite surfaces the elemental composition of fossil bone from the early jurassic dinosaur dilophosaurus is distinguished by elevated as ppm generally not present in the late cretaceous dinosaurs we suggest that as is adsorbed from the reductive dissolution of as rich iron oxyhydroxides in the local aquifer and is not reflective of mesozoic atmospheric conditions or arsenic toxicosis in dinosaurs pixe allows us to reaffirm that the histological structure tissue density and high surface area of the vascular canals of dinosaur haversian bone affect postmortem elemental enrichment and depletion and to quantify these differences at scales as small as 1 5 m

late pleistocene recent marine malacological assemblages of the colorado river delta south of buenos aires province paleoecology and paleoclimatology abstract the most recent quaternary marine transgressions are well represented along the south atlantic coast in the colorado river delta 39 15 s 39 55 s south of buenos aires province these deposits are mostly littoral ridges and tidal plains with abundant fossil marine fauna seventeen localities were analyzed five pleistocene seven holocene and five modern ones representing the interglacials mis 9 mis 5e and mis 1 a total of 51 species were recorded 29 bivalves and 22 gastropods together with nine micromolluscs mis 1 and the modern coast 37 and 42 species respectively are the richest ones in species unlike mis 5e and mis 9 18 and 2 species respectively in mis 9 the most abundant species is pitar rostratus mis 5e and mis 1 have in common the presence and abundance of the gastropod heleobia australis and the bivalve tagelus plebeius as typical fauna of low energy environments being the bivalve glycymeris longior and the gastropods bostrycapulus odites and buccinanops globulosus common species in both kinds of marine deposits approximately 90 of bivalves and 75 71 of gastropods of the marine fauna are recorded from mis 5e to the present according to the different descriptive analyses bray curtis index and ac the molluscan fauna was grouped in two and five assemblages respectively defined by age type of deposit and presence and or abundance of species marine species represented in the area of the colorado river delta vary in abundance among the interglacials but not in faunal composition one of the possible causes would be the global climatic changes e g rise of sea surface temperature sst and the heterogeneity of habitats that would have conditioned the development of the different faunal assemblages during the quaternary

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

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

paleoenvironmental interpretations of rare earth element signatures in mosasaurs reptilia from the upper cretaceous pierre shale central south dakota usa abstract rare earth elements were analyzed from fossil marine reptile mosasauridae bones collected from five superposed members sharon springs gregory crow creek degrey and verendrye of the upper cretaceous pierre shale at localities along the missouri river in brule buffalo hughes and hyde counties in central south dakota fossil bones from each member of the pierre shale have different rare earth element ree signatures that may be distinctive over wide geographic areas fossils from the sharon springs member have distinctive ree signatures that may be further subdivided into three superposed groups that correspond with the upper middle and lower sharon springs member ree signatures are distinctive from each stratigraphic unit therefore fossils eroded from their stratigraphic context may be assigned to their proper depositional unit based on ree signature comparisons differences in ree compositions of bones among members appear to result from differential mixing of oxygenated and anoxic seawaters if differences in mixing are interpreted as depth differences the lower sharon springs member was deposited in deep anoxic water water depths decrease in the middle and upper sharon springs and the overlying gregory and crow creek members were deposited in even more shallow water finally according to this interpretation the overlying degrey and verendrye members were deposited in progressively deeper marine waters but not as deep as the lower sharon springs these interpretations are generally consistent with those based on faunal diversity and eustatic sea level curves

oxygen isotopic composition of fossil equid tooth and bone phosphate an archive of difficult interpretation abstract variation in the concentration of the stable isotopes of hydrogen oxygen and carbon have been tested in continental records as tools for quantitative or semi quantitative paleoclimatological studies among the different methods the potential use of oxygen isotopes in mammal bone and tooth phosphate has recently been recognized measurements carried out on fossil mammal bones of holocene age and their paleoclimatological interpretation corresponded well with paleontological and paleobotanical records in the case of considerably older fossils diagenetic processes may change the primary oxygen isotopic composition of phosphate fossil horse bones and teeth principally of the species equus stenonis were studied to ascertain how far back in time fossil mammal remains may be considered reliable material for paleoclimatological studies the samples come from 13 different locations in southeastern spain their age ranging from maspinian late pleistocene to middle villafranchian pliocene apart from the variations of the 18o po43 values which may be related to climatic changes it is apparent that the isotopic composition of bones and teeth from the same deposit are frequently rather different from one another the isotopic differences range from a few tenths of one to several this suggests a strong influence of taphonomy over the measured isotopic values of fossils in each deposit time can be considered neither the only variable nor the most important one responsible for the change of the primary isotopic composition of fossils under these conditions it is rather difficult to establish lower or upper limits for the age of fossils to be studied for reliable paleoclimatological information since the limits are directly related to taphonomic history this in turn is related to local environmental conditions and not only to the age of fossils

geochemical taphonomy of shallow marine vertebrate assemblages abstract combined histological and geochemical analyses demonstrate complex processes leading to preservation of microbially altered bone in certain situations a chemical microenvironment distinct from surrounding pore waters is developed and maintained within the bone the bone acts as a closed system and hence palaeoenvironmental interpretations based on fossil bone apatite chemistry may not accurately reflect overall geochemical conditions of the sedimentary deposits where the bones were buried geochemical techniques based on variance in trace element compositions of bones from different assemblages can be used as a measure of the relative degree of mixing or taphonomic averaging within marine vertebrate assemblages

diagenetical changes in pleistocene small mammal bones from olduvai bed i abstract fossil bones of small mammals from two levels at olduvai bed i tanzania were analysed for a range of elements using electron microprobe techniques comparison of the fossil samples is made with those of recent samples collected from close to the natron alkaline lake tanzania values for the elements na sr ba are significantly higher and s lower in the fossil samples relative to the recent samples in addition concentrations of the rare earth elements reach exceptionally high concentration levels i e 6 wt in one of the sites whereas these elements are not detected in the recent samples the high concentrations of these elements in the fossil samples are clearly a result of diagenetic alteration although the effects of digestion are likely to have had some influence on the processes involved in the incorporation of elements during fossilisation statistical analyses show there are significant differences in the chemical compositions of fossil bones from two levels in bed i observed changes in the rare earth element patterns in particular the ce anomaly suggest that relative differences in the redox potentials of the burial and depositional environments existed at the two levels fluctuations in the size and extent of the palaeolake are considered to be the likely cause of these differences

evidence of two temperate episodes in late pleistocene deposits at marsworth uk in the british quaternary two post cromerian interglacials the hoxnian and the ipswichian are recognized1 evidence of additional interglacials in this interval is widely accepted in the oceanic record of quaternary events2 and the possibility that at least one additional interglacial of this age is represented in britain has been discussed3 5 however in the absence of datable interglacial deposits which are seen to overlie one another the issue has remained controversial we describe here deposits at marsworth uk fig 1 where there is evidence of two temperate episodes and of intervening periglacial conditions stratigraphical superposition is established beyond any reasonable doubt the later deposit relates to the temperate woodland stage of the ipswichian interglacial dating of the earlier temperate material by the 230th 234u disequilibrium method indicates an interglacial episode not previously established in the british quaternary

the variation of the trace element content of fossil biogenic apatite through eustatic sea level cycles shark teeth from the oligocene boom clay formation belgium have been analyzed for trace elements by neutron activation analysis to examine whether biogenic apatite might record changes in seawater trace element chemistry throughout a eustatic sequence an additional set of samples from a wide range of depositional environments has been studied to shed light on the nature of factors that govern the trace element variation of fossil apatite biogenic apatite samples from a given sedimentary basin exhibit rather specific and distinctive trace element fingerprints which shows that they reliably record geochemical parameters of the sedimentary environment it appears that sea level changes do not substantially affect geochemical processes in an epicontinental marine sedimentary basin but minor chemical changes do coincide with sequence stratigraphic levels slightly higher la yb ratios correlate with periods of higher turbulence positive ce anomalies indicate that a large fraction of the kee adsorbed by the shark teeth can be derived from the upward flux of reduced pore water this process greatly diminishes the usefulness of the ce anomaly as a palaeoredox probe a factor analysis performed on trace element data and sedimentary environment parameters suggests that ree contents ree sc and th ree ratios are related to sediment input c 1997 elsevier science b v

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

pleistocene fluvial sediments palaeontology and archaeology of the upper river thames at latton wiltshire england pleistocene fluvial sediments of the northmoor member of the upper thames formation exposed at latton wiltshire record episodic deposition close to the churn thames confluence possibly spanning the interval from marine isotope stages mis 7 to 2 the sequence is dominated by gravel facies indicating deposition by a high energy gravel bed river a number of fine grained organic sediment bodies within the sequence have yielded palaeoenvironmental and biostratigraphical data from mollusca coleoptera vertebrates pollen and plant macrofossils the basal deposit facies association a contains faunal material indicating temperate conditions most of the palaeontological evidence including a distinctive small form of mammoth mammuthus cf trogontherii together with the u series age estimate of 147 4 20 kyr suggest correlation with mis 7 the overlying deposits facies associations b and c represent deposition under a range of climatic conditions two fine grained organic deposits occurred within association b one association ba in the northern part of the pit as a channel fill and the other association bb in its southern part as a scour fill deposit the coleopteran assemblages from ba indicate that it accumulated under temperate oceanic conditions while bb which also yielded a radiocarbon age estimate of 39 560 780 14c yr bp was formed under much colder and more continental climatic conditions the sequence is considered to represent deposition within an alluvial fan formed at the churn thames confluence a depositional scenario which may account for the juxtaposition of sediments and fossils of widely differing age within the same altitudinal range

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

uranium and thorium distributions in fossil bones from olduvai gorge tanzania and kanam kenya abstract the micro distributions of uranium and thorium have been studied in fossil bone cortices in samples from olduvai gorge tanzania and kanam kenya and compared with modern bones collected from the surface at olduvai gorge concentrations in excess of 800 ppm u and 200 ppm th are recorded in sections of some fossil bones whereas concentrations do not exceed 20 ppm u or 1 ppm th in the modern bones in fossil bones th has a larger intra bone variation than u the distribution profiles of the two elements across the fossil bone cortices are quite distinct and reflect differences in their geochemical behaviour in the supergene environment in particular the two possible oxidation states of u compared with one for th allow u to be more mobile than th but also more susceptible to variations in the redox potential of the depositional environment in some fossil bone samples secondary leaching of u has occurred whereas th is retained in the bone cortex u is incorporated into fossil bone earlier than th

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

organic geochemistry petrology and palynofacies of middle devonian lacustrine flagstones in the orcadian basin scotland depositional environment thermal history and petroleum generation potential during middle devonian time a thick succession of organic rich mainly lacustrine flagstones developed within the orcadian basin these petroleum source rocks crop out in northern scotland nineteen samples were studied using organic petrology palynology and organic geochemistry in order to characterize kerogen type depositional environment thermal maturity and petroleum generation potential c org carbonate and sulphur content as well as hydrogen index hi values are quite variable e g hi from 79 to 744 mg hc g c org based on biomarker data organic material mainly originates from aquatic organic matter deposited under lacustrine conditions with oxygen depleted but not permanently anoxic bottom waters petrography reveals small quantities of vitrinite particles indicating minor input of terrestrial material this is supported by biomarker data and the palynofacies which is characterized by a high amount of oil prone amorphous organic matter aom and generally few miospores maturity of the succession studied in caithness and orkney is between immature and oil mature one dimensional basin modelling shows that a significant remaining hydrocarbon generation potential exists within the middle devonian succession in contrast to the low hydrocarbon generation in the onshore area offshore oil generation was significant especially after deposition of thick upper jurassic upper cretaceous sediments at the end of cretaceous time hydrocarbon generation ceased due to uplift the contribution to known oil fields from the devonian flagstones is a realistic scenario including a contribution to the beatrice oil field in the south of the modelled area

wolverine in northern england at about 83 000 yr b p faunal evidence for climatic change during isotope stage 5 abstract cave sediments from stump cross cave in northern england contain pleistocene mammal remains uranium series dating of calcium carbonate deposits closely associated with the fossiliferous horizons has established an absolute age of 83 000 6000 yr b p for a faunal assemblage largely comprised of wolverines gulo gulo this date lies firmly within the younger portion of oxygen isotope stage 5 the occurrence of wolverines in the vicinity of stump cross cave at ca 83 000 yr b p indicates a significant climatic deterioration from ca 120 000 yr b p when an ipswichian interglacial fauna with hippopotamus was present in this part of northern england

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

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