oxygen isotopic composition of fossil horse tooth phosphate as a record of continental paleoclimate abstract oxygen isotopic elemental and x ray data are presented for a suite of 24 fossil horse teeth from nebraska ranging in age from 18 2 to 8 5 ma to test the use of 18o of enamel phosphate 18op04 as a quantitative record of continental climate modern equid teeth were analyzed to estimate a relationship between 8op04 and environment water multiple samples of seven different fossil species from burge quarry a 12 ma attritional fossil deposit indicate the diagenetic overprints exist but can be detected by decreased p concentration and increased crystallinity relative to modern enamel isotopic variation for the pristine samples from burge quarry is 1 5 1 n 9 which may represent the resolution of the procedure within a stratigraphic horizon there are no apparent correlations with body size hypsodonty or phylogeny a range of 7 0 in 18op04 occurs over the 10 m y interval a trend towards depleted 18op04 of about 4 corresponds to a depletion of up to 6 0 in 18o of precipitation between 18 2 and 8 5 ma but the range of variation of burge is large relative to the climate signal our results demonstrate that 18op04 should be useful in quantitatively reconstructing cenozoic continental paleoclimate on 106 year timescales isotopic variation due to taphonomic bias and the terrestrial rock record will likely obscure higher order climate signals

effects of hydrothermal alteration on the compositions of chromian spinels chromite spinels in hydrothermally altered rocks from fracture zone ultramafic rocks and from both ultramafic cumulate pods and sheeted dikes in the josephine ophiolite california display a wide variety of compositions alteration of the spinel may not be visible in thin section the primary composition changes accompanying hydrothermal alteration are increase in cr cr al and or fe2 fe2 mg in general altered spinel grains associated with hornblende and chlorite show an increase in cr cr al from core to rim altered spinel grains associated with serpentine show an increase in fe2 fe2 mg from core to rim but may not show an increase in cr cr al the compositional zoning in some altered spinel grains appears to result both from reaction of clinopyroxene plus spinel to form hornblende and from reaction of hornblende to form chlorite these observations suggest that subsolidus hydrothermal metamorphic effects need to be considered when interpreting spinel compositions and the compositions should not be interpreted solely in terms of igneous processes further the presence of highly altered spinels may be indicative of hydrothermal alteration in rocks where other evidence of such alteration is absent

stable isotope composition and rare earth element content of vertebrate remains from the late cretaceous of northern spain lano did the environmental record survive abstract oxygen and carbon isotope measurements have been performed on phosphatic remains from faunal associations dinosaurs crocodiles turtles and fish of the late cretaceous continental and marine sediments from northern spain basque country the environmental meaning of the oxygen isotope record in fossil reptiles is discussed on the basis of known paleoecology modern fauna analogs and apatite chemistry rare earth elements ree co32 and po43 contents fossil remains in sandstones and argillites from two localities urria and cuezva have low down to 16 and scattered 18o po4 co3 and 13c values with ree patterns characterized by strong middle ree enrichments these geochemical compositions of the biogenic apatites have most likely been acquired during a multi stage late diagenesis involving complete recrystallization of the apatite in the presence of aqueous fluids ree contents of fossils preserved in the clayey sands from the site of lano suggest that samples have only been affected by early diagenesis despite the diversity of analyzed taxa and the close association of marine sharks and rays and freshwater species crocodiles and turtles evolving in a littoral environment the narrow range of phosphate 18o values is interpreted as reflecting the temperature and isotopic composition of groundwaters that prevailed in the burial environment the potential information relative to the physiology and thermal regime of the vertebrates has been erased during the process of early diagenesis if all oxygen in the phosphate has exchanged with groundwaters the oxygen isotope composition of vertebrate remains suggests that a warm climate t 20 25 c prevailed in northern spain during the late cretaceous

latitudinal temperature gradient during the cretaceous upper campanian middle maastrichtian y18o record of continental vertebrates latitudinal variations in model biogenic apatite d18o values were calculated using fractionation equations of vertebrates and weighted rainfall y18o values along with mean annual air temperatures provided by iaea wmo meteorological stations the reference equation obtained was used to compute a continental temperature gradient for the late campanian middle maastrichtian interval by using published and new d18o values of phosphate from vertebrates samples are mainly tooth enamel from crocodilians and dinosaurs that lived at paleolatitudes ranging from 83 4 n alaska to 32 3 s madagascar the temperature gradient was less steep 0 4 0 1 c latitude than the present day one 0 6 c latitude with temperatures that decreased from about 30 c near the equator to about 5 c at the poles above 30 of paleolatitude air temperatures were higher than at present the validity of these results is discussed by comparison with climatic criteria inferred from paleontological paleobotanical and sedimentological data the latitudinal distribution of oxygen isotope compositions of continental vertebrates is potentially a powerful tool for quantifying mesozoic terrestrial climates

implications for the late pleistocene climate in finland and adjacent areas from the isotopic composition of mammoth skeletal remains nine samples of subfossil bone and teeth remains from woolly mammoth mammuthus primigenius discovered in finland russian karelia and western russia were analyzed for the oxygen isotope composition of the phosphate fraction and the carbon and oxygen isotope composition of the carbonate fraction in skeletal apatite the samples have been radiocarbon dated in previous studies and are of late middle weichselian to late weichselian age the preservation of the samples was tested analyzing the chemical composition and checking the isotopic equilibrium between the phosphate and carbonate components in skeletal apatite according to these tests five out of the nine samples were determined to have retained their original isotopic composition these samples were used to estimate late pleistocene climatic conditions in finland and neighboring areas based on the best preserved enamel samples the isotopic composition of oxygen in late pleistocene precipitation was 1 3x lower than that in the mean annual precipitation in southern and central finland today using the relationship between the isotopic composition of precipitation and the ambient temperature it can be estimated that the mean temperatures during the middle weichselian ice free period were 2 6 8c lower compared to the present day values d 2005 elsevier b v all rights reserved

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

palaeoclimatic information from isotopic signatures of late pleistocene ursus ingressus bone and teeth apatite loutra arideas cave macedonia greece abstract bones and teeth samples of ursus ingressus from loutra arideas cave greece were used to determine the diet of this extinct species and to reconstruct the palaeoclimatic conditions the age range of the fossil layers is from 32 ka bp to a maximum of 38 ka bp radiocarbon dating the method used was the isotopic analysis of carbonate bioapatite of fossil cave bear u ingressus and brown bear ursus arctos bone and tooth fragments as well as water samples from springs of the pindos area the modern bear habitat several possible effects that may affect the isotopic composition of apatite were investigated including age sex tooth type and diagenesis the comparison of isotopic values of greek u ingressus to other pleistocene ursidae species in europe exhibit more positive and more variable 13 c values these positive values are attributed mainly to diet to bear physiology differences among species and to climate conditions the diet of u ingressus apparently was based mainly on vegetable matter however with a variable component of animal protein the variation observed in the 18 o values of u arctos tooth enamel samples were attributed to environmental conditions and through the spring waters isotopic gradient for the region of northeastern pindos to differences in the bear s habitat elevation assuming similarity of the metabolism of modern and fossil bear species and incorporating only the effect of drinking water on the isotopic composition of body water an equation has been derived that could be used to provide palaeoclimatic information

the 200 000 year long record of stable isotopes δ18o δ13c of cave bear ursus spelaeus teeth from biśnik cave poland abstract the excavations in bi nik cave created an opportunity to investigate changes in 13c and 18o values of ursus spelaeus teeth from one site along a 200 000 year period of sedimentation for the first time in eastern europe bi nik cave krakow czestochowa upland southern poland is a multilayered archaeological and paleontological site with late middle pleistocene and late pleistocene sediments where several important changes of quaternary climate have been recorded the project considered if and how detailed the isotopic data from one multilayered site record these great climatic changes the method used was an isotopic analysis of carbonate in bioapatite from tooth enamel teeth of cave bear u spelaeus were chosen as research material the results showed that the 18o values of cave bear teeth from bi nik cave range from 14 9 to 4 4 vpdb with some variation between particular layers values of 13c vary between 20 5 and 14 5 vpdb the analysis revealed that isotopic record is diverse between different types of teeth probably due to differences in time of growth and different impact of nursing and hibernation the results verify the responsiveness of this species to great climatic changes during middle and late pleistocene in eastern europe cave bear was an ecologically inflexible species associated with the same type of food during 200 000 years and not able to cope with the coldest phases of the pleistocene

terrane accretion in the internal zone of the ungava orogen northern quebec part 1 tectonostratigraphic assemblages and their tectonic implications the tectonostratigraphic record of the ungava orogen contains evidence for the interaction of divergent transform and convergent plate boundaries over a 0 2 ga period in the early proterozoic three principal tectonic domains are recognized 1 autochthonous basement plutonic and supracrustal rocks of archean age 2 autochthonous and allochthonous sedimentary and volcanic units associated with a ca 1 99 1 92 ga rift to drift margin and 3 suspect crustal components of a ca 2 00 ga ophiolite and ca 1 90 1 83 ga island arc terrane domain 1 is the stratigraphic or structural basement to domains 2 and 3 field relationships indicate that domain 2 units were accumulated on or near domain 1 whereas no tectonostratigraphic linkages are known between domain 3 and the others accumulation of continent derived sedimentary rocks continental tholeiites komatiitic basalts and mafic lavas equivalent to modern normal mid oceanic ridge basalts n morb s in domain 2 is interpreted as recording continental rifting leading to the possible formation of oceanic crust pillowed basalts sheeted dykes and cumulate rocks suggest that the crustal portion of an ophiolite is preserved within domain 3 the ophiolite is interpreted as a suspect fragment of oceanic crust which may represent an earlier rifted portion of domain 2 possibly juxtaposed by transform plate boundary motions within domain 3 calc alkaline volcanic and plutonic units and sequences of volcanogenic and siliciclastic sedimentary rocks are thought to indicate the development of a magmatic arc and fore arc basin and thus the establishment of a convergent plate boundary the most internal lithotectonic packages in domain 3 are predominantly crystalline thrust sheets containing i an older intrusive suite interpreted as the plutonic foundation of the magmatic arc and ii younger plutons interpreted as the result of a reversal in subduction polarity the reversal may have followed attempted subduction of domains 1 and 2 beneath the upper plate arc assemblage of domain 3

sandstone hosted thorium bitumen mineralization in the northwest irish basin low grade sandstone hosted thorium mineralization is recorded in the carboniferous northwest irish basin in the republic of ireland and northern ireland the thorium is concentrated within bitumen nodules which are replacive within the sandstones a source of thorium was available in a caledonian granite in the basin watershed and the bitumen was a product of hydrocarbons generated within the basin the thorium occurs as thorite inclusions in the bitumen and the development of the nodules was enhanced by the polymerization of fluid hydrocarbons by irradiation from the thorium thorium mobility may have been enhanced by the formation of organometallic complexes mineralization probably therefore occurred during hydrocarbon migration dated as late carboniferous to permian

oxygen isotope variation in the tusks of extinct proboscideans a measure of season of death and seasonality centimetre scale laminae in tusk and molar dentine of late pleistocene mastodonts and mammoths have been interpreted as annual growth bands produced in part by seasonal variation in growth rate to test this interpretation we measured the oxygen isotope composition 18 o of the co 3 fraction of dentinal hydroxyapatite from samples covering consecutive inferred years of growth in tusks in mammals changes in the 18 o value of dental tissues within individuals predominantly reflect variation in the 18 o value of body fluids which is controlled mainly by the isotopic composition of ingested water in northern hemisphere continental regions winter precipitation has substantially lower 18 o values than does precipitation in other seasons if ingested water tracks focal precipitation then seasonal variations in dentinal isotope composition should result the lowest 18 o values representing winter growth we demonstrate that there are substantial variations in the oxygen isotope composition of proboscidean dentinal apatite and that isotopic identifications of winter i e low 18 o values coincide with those based on growth rate i e slow growth zones finally the potential of oxygen isotope analyses of terrestrial mammals for assessing the seasonality of paleoclimates is considered

isotopic reconstruction of past continental environments abstract vertebrate fossils and continental sediments provide a rich record of variations in the isotopic composition of surface environments to interpret these records a greater understanding of isotopic sources as well as fractionations associated with animal physiology soil geochemistry and diagenesis has been essential tooth enamel and fish otoliths yield subannual records of surface environments whereas soil minerals may integrate signals over many thousands of years carbon isotope variations in fossil vertebrates and soils record changes in the structure of vegetation and the isotope composition and concentration of atmospheric co2 oxygen isotope variations may be indirectly related to climate through reconstruction of the oxygen isotope composition of meteoric water or directly related to temperature through application of oxygen isotope paleothermometry to soil minerals or otoliths in africa nitrogen isotope variations show promise as a proxy for rainfall abundance though the gen

stable carbon and oxygen isotopic evidence for late cenozoic environmental change in northern china abstract stable carbon and oxygen isotope ratios of 311 enamel samples from a diverse group of herbivorous mammals including equidae rhinocerotidae bovidae rodentia and ochotonidaewere were analyzed in order to reconstruct the late cenozoic history of vegetation and environmental change in the yushe basin in north china the 13c values of bulk and serial enamel samples from large mammals show a wide range of variation from 13 3 to 1 4 with a mean of 7 4 3 5 n 294 this indicates that large herbivorous mammals in the area had a variety of diets since 6 5 ma ranging from pure c3 to mixed c3 c4 and pure c4 diets in contrast the 13c values of small mammals vary from 11 9 to 7 6 with a mean of 9 7 1 1 n 17 indicating that rodents and ochotonids were feeding mostly on c3 plants variations in 13c values within and between species reflect the variations in the habitat and the vegetation consumed by the animals in general horses had higher amounts of c4 grasses in their diets than other contemporary taxa such as bovids rhinos rodents and deer suggesting that horses exploited more open habitats such as grasslands while deer rhinos and rodents may have preferred more c3 vegetation which is more indicative of forested environments the carbon isotope data show that c4 grasses have been an important component of horses diets and of local ecosystems since 6 5 ma confirming that the late miocene c4 expansion occurred in north china as it did in africa indian subcontinent and the americas this supports a global factor as a main driver of the late miocene c4 expansion the combined carbon and oxygen isotope data reveal major shifts in climate to drier and or warmer conditions after 5 8 4 1 3 3 and 2 5 ma and significant shifts to relatively wetter and or cooler conditions after 6 4 5 3 5 ma the shifts to drier and or warmer climate after 5 8 ma and 2 5 ma coincide with two major fauna turnover events intra tooth 13c and 18o values are negatively correlated within individual modern teeth and some fossil teeth displaying the characteristic pattern of the summer monsoon regime and confirming a strong monsoon influence in the area since at least the early pliocene the data also suggest that the c4 abundance in the area has fluctuated over the past 6 5 ma in response to changes in climate with more c4 grasses during warmer and or drier periods and a reduced c4 component at cooler and or wetter times

highly alkaline lavas in a proterozoic rift zone implications for precambrian mantle metasomatic processes an occurrence of proterozoic nephelinite and basanite lavas and pyroclastic rocks and associated phonolites indicates that the processes that generate modern alkaline magmas in intraplate settings were operative in the early proterozoic these lavas occur near the top of a 1 9 ga continental margin sequence in the cape smith fold and thrust belt of northern quebec the lavas are classified as nephelinites basanites and phonolites on the basis of high field strength and rare earth element contents although large ion lithophile elements including alkalis appear to have been strongly depleted by greenschist facies metamorphism and alteration certain major elements define trends consistent with low pressure fractionation dominated by clinopyroxene which is the only mafic phenocryst present in the lavas the mafic and felsic lavas have identical 143 nd 144 nd ratios consistent with consanguinity and a lack of contamination by older crust of the superior province values for nd 1 96 ga of 2 represent an enriched mantle source relative to 4 to 5 for the contemporaneous mid oceanic ridge basalt reservoir

paleoproterozoic carbonatitic ultrabasic volcanic rocks meimechites of cape smith belt quebec a 500 m thick lens of carbonatitic ultrabasic lapilli tuffs and lavas interbedded with platformal povungnituk sediments in the foreland of the cape smith belt is its earliest known magmatism and may relate to its initial rifting the sequence comprises tuffs capped in part by effusives accretionary and cored lapilli in the tuffs and pillows in the lavas suggest emplacement in a shallow marine environment its current assemblage of antigorite chlorite talc and in part primary carbonate magnetite ilmenite minor chromite and phlogopite results from probable concurrent hydro thermal alteration and subsequent greenschist regional metamorphism surviving accessory minerals apatite monazite zircon rutile and aeschenite are widespread but scarce carbonate mostly dolomite is a major and integral component of the rock and interpreted as an original albeit recrystallized magmatic constituent magnetite is conspicuous in the tuffs as lapilli and lapilli cores locally as giant crystals and as stringers except in subhedral groundmass crystals its negligible tio2 is evidence of its hydrothermal reconstitution compositions of chromite cores and rare relicts of phlogopite crystals are consistent with mantle derivation rock compositions are low in sio2 25 wt and alkaline the immobile incompatible elements e g zr average 260 ppm nb average 130 ppm and the light rare earth elements are enriched the rocks are compositionally similar to type siberian meimechites and closely resemble the meimechite carbonatite eruptives of castignon lake labrador trough based on experimental evidence lac leclair magmas are interpreted as originating by minor partial melting of carbonated mantle at 100 km depths and reaching the surface via conduits opened by deep rifting that initiated the cape smith segment of the trans hudson orogen

stable isotope distribution in maastrichtian vertebrates and paleosols from the haţeg basin south carpathians abstract located in the south carpathians in romania the ha eg basin contains a thick sequence of maastrichtian continental deposits yielding a rich dinosaur and mammalian fauna stable isotope analyses of both calcretes and dinosaur crocodilian and turtle remains from two localities tustea and sibisel were integrated in order to reconstruct environmental conditions during maastrichtian time and to gain further insights into the metabolism and behaviour of the vertebrates the large difference observed between the 18o and 13c of the eggshells and the surrounding mudstones as well as the preservation of the 9 difference between the oxygen isotope composition of the telmatosaurus eggshell and tooth enamel indicate that diagenesis has not significantly altered the primary isotopic signal the presence of smectite in the fraction less than 2 m and the preservation of dinosaur eggshell structure also indicate that diagenesis was not significant in the studied outcrops stable isotope compositions of both calcretes and phosphatic remains suggest warmer conditions during the deposition of the tustea sequence mean annual temperature of around 14 c than during the deposition of the sibisel sequence mean annual temperature of 10 c the intra tooth 18o patterns for zalmoxes and allodaposuchus show different magnitudes of isotopic variation with lower values for tustea and higher for sibisel the calculated 18obody water enrichment for kallokibotion bajazidi is similar to that found in living turtle taxa by contrast in the case of allodaposuchus the isotopic enrichment is higher than for recent taxa this suggests that for allodaposuchus the body water was less buffered by a watery environment which probably indicates more time spent outside water i e more terrestrial habit the 18o values for the teeth of telmatosaurus and zalmoxes are similar to those of allodaposuchus suggesting that at the investigated sites the body temperature of both dinosaurs was similar to that of the crocodile the isotopic composition of calcretes teeth and eggshells indicates a c3 vegetation and diet with 13c values between 27 and 29 pdb and the absence of large scale habitat partitioning between the dinosaurs

the bear necessities a new dental microwear database for the interpretation of palaeodiet in fossil ursidae abstract this study presents a new database of dental microwear features for extant bear species which is used to interpret palaeodiet in brown bear ursus arctos from the late middle pleistocene site of grays thurrock u k applying light stereomicroscopy techniques in dental microwear analysis we highlight for the first time that the talonid area of the first lower molar m1 in extant ursids is most effective in the differentiation of dietary ecospaces extant bear species can be separated into different parts of a dietary ecospace revealing microwear features that mirror their dietary preferences of particular note is the differentation of ecospaces within modern brown bear populations from different geographical regions and the potential for identifying seasonal variation in diet the results demonstrate that the diet of thelate middle pleistocene brown bear from the interglacial site of grays thurrock was closely comparable to that of the modern u arctos from northern europe the american black bear ursus americanus and the sun bear helarctos malayanus this suggests the dietary importance of fibrous food as well as soft fruits and invertebrates and a small vertebrate component this finding is in agreement with climatic conditions and habitats inferred for the mis 9 interglacial the creation and testing of a dental microwear database for all modern bear species provides a foundation for subsequent application to other extinct pleistocene bear populations

petroleum geochemistry of the lower and middle jurassic in atlantic margin basins of ireland and the uk potential hydrocarbon source rocks of lower and middle jurassic age have been reported from outcrop shallow boreholes and exploration wells in atlantic margin basins of the uk hebrides west of shetlands and flanking the ne rockall trough and recently in the continuation of this trend offshore ireland slyne erris and porcupine basins previously these organic rich mudrocks were considered to be of little economic importance due largely to their perceived limited areal distribution and low maturity however recent geochemical studies of oils and shales from exploration drilling of these basins shows the lower and middle jurassic to have considerable potential as effective hydrocarbon source rocks supplanting the late jurassic early cretaceous kimmeridge clay formation equivalents as the only viable oil source rock in the region flanking the atlantic margin in the irish and uk sectors rich oil source potential occurs in two transgressive mudrock cycles of lower jurassic age these are the sinemurian pliensbachian interval and the overlying toarcian section present in basins such as the solan minch hebrides slyne north celtic sea st george s channel and central english channel the middle jurassic source rocks have a more limited areal distribution and occur in the faroe shetland solan west lewis west flannan hebrides slyne and north porcupine basins with oil source potential in regressive marginal marine to lacustrine facies mudrocks geochemical studies were undertaken on mudrocks from the lower and middle jurassic sections in atlantic margin basins outcrop shallow borehole core and exploration well cores and cuttings samples and on oils from drill stem test and shows core and cuttings extracts detailed analyses using gc gc ms and carbon isotopes allowed both characterization of the source rocks and oil to source correlation biomarker and carbon isotope studies of oils from the faroe shetland basin foinaven and schiehallion fields the porcupine basin connemara accumulation the wessex basin wytch farm and kimmeridge oil fields and wells in the slyne basin show strong correlations to the various source rock developments in the lower and middle jurassic the mixed biodegraded foinaven and schiehallion oils have a major waxy component and correlate with lacustrine middle jurassic source rocks in the solan and west lewis west flannan basins middle jurassic sourcing of the connemara oils is also suggested while oils in the slyne basin appear to have been largely sourced by the lower jurassic pabba shale formation oils in the wessex basin wytch farm and kimmeridge appear to have been sourced by hettangian sinemurian mudrocks and those in the north celtic sea basin by toarcian source rocks the results from this study in combination with previously published data show that rich effective oil prone source rocks occur in both the lower and middle jurassic of the atlantic margin basins offshore ireland and the uk these source rocks can be correlated with indigenous oils indicating the existence of a previously under evaluated petroleum system

u pb ages from the nimish formation and montagnais glomeroporphyritic gabbro of the central new quebec orogen canada three u pb zircon dates were obtained from two igneous suites associated with cycle 2 sedimentation in the central new quebec orogen labrador trough in the dyke lake area of the western part of the orogen schefferville zone the nimish formation includes a polymictic conglomerate containing quartz syenite cobbles that crystallized at 1877 8 1 3 ma these cobbles are petrographically and geochemically linked to the nimish volcanics which are intercalated with the sokoman iron formation consequently the syenite date gives an approximate age for both nimish magmatism and ironstone deposition in the schefferville zone a date of ca 2 65 ga obtained from a nimish trachyte in the same area indicates that zircons in the sample are xenocrysts farther east at howse lake howse zone a montagnais plagioclase glomeroporphyritic gabbro sill crystallized at 1884 0 1 6 ma the howse lake sill which intrudes turbidites of the menihek formation is considered comagmatic with the basalts that cap the form

ratios of cave bear tooth enamel a record of climate variability during the pleistocene the oxygen isotope composition of apatitic phosphate in the teeth and bones of certain animals reflects the oxygen isotope composition of the water they ingest the isotopic composition of meteoric water is in turn well correlated with mean annual temperature so that there is potential for recovering paleotemperatures of the regions where the animals lived cave bear teeth have been examined for this purpose analyses were made of enamel from 53 canine teeth of cave bears males females adults and juveniles from 4 sites in spain phosphate was isolated as ag3po4 and reacted with graphite to produce co2 for isotopic analysis reproducibility of the analyses was normally 0 1 0 2 the oxygen isotope compositions of teeth from both the coastal site of cueva de santa isabel 350 200 ka and the inland site of cueva mayor 350 ka were uniform 1 4 total variation per site with mean 18o values of 18 9 and 17 2 respectively interpretations of these data include differences in global temperature between glacial and interglacial periods and differences due to geographic locations of the sites e g elevation and distance from the sea the teeth from cueva del reguerillo 90 60 ka in central spain were more variable in isotopic composition with an average value between those of teeth from the other caves cave bear teeth appear to preserve their original oxygen isotope composition can be dated and occur in abundance in many locations of europe and the near east the abundance of the teeth and their large size allows samples used for paleoclimate studies to be restricted to enamel of one type of tooth the 18o values of enamel and dentine from one tooth commonly differ thus the comparison of oxygen isotope composition among teeth from different individuals sites or times is facilitated if only enamel is used restricting analyses to only one type of tooth reduces variability due to changes of diet during the period of tooth growth the simple evolutionary line of descent of cave bears and the small number of species reduces the effects of interspecific differences in oxygen isotope fractionation they thus provide a good potential source of material for detailed investigations of pleistocene climates

upb geochronology of the western cape smith belt canada new insights on the age of initial rifting and arc magmatism abstract the cape smith belt of northern quebec is the foreland to hinterland transition of the ungava orogen a component of the paleoproterozoic trans hudson orogen of north america u pb ages for rift and volcanic arc related units from the cape smith belt are presented and used to evaluate models of its tectonic evolution a gabbroic sill intrusive into the rift related sediments near the base of the povungnituk group is 2038 2 4 ma old indicating that rifting of the superior province was initiated prior to that time 80 m y earlier than previously reported a granodiorite intrusive into the volcanic rocks of the povungnituk group is dated at 1991 2 ma indicating that magmatism associated with the rifting event was active at that time 30 m y earlier than formerly thought the age of parent group arc related magmatism ranges from 1874 3 4 ma the age of a diorite intrusion to 1860 2 ma the age of another diorite intrusion and of a rhyolite a granodiorite intrusive in the parent group yields an age of 1845 6 ma magmatism of the parent group is thought to be related to northward dipping subduction of the superior province margin below the watts group a gabbroic intrusion in the 2000 ma old watts group is dated at 1858 2 ma these ages are consistent with a tectonic model in which the rocks of the cape smith belt formed in a single continental rift to oceanic progression followed by subduction which led to an arc continent collision a comparison of u pb ages for similar events in different sectors of the trans hudson orogen in canada reveals that early events are diachronous and range from 2169 ma to 2038 ma the main collisional events are coeval in the ungava and new quebec orogens and in some of the western sectors at 1830 1860 ma younger ages of 1800 1820 ma are obtained for the late collisional stages throughout the trans hudson orogen

reflections of surface water seasonality and climate in stable oxygen isotopes from tyrannosaurid tooth enamel abstract patterns of isotopic variation in enamel of eight albertosaurus teeth from the campanian maastrichtian horseshoe canyon formation alberta were measured by serial sampling along the growth axis cycles in the isotopic values appear to correlate to published tooth growth rates for tyrannosaurids tyrannosaurid dinosaur teeth of 50 mm in length provide ideal repositories of terrestrial climatic information as each records a full annual cycle of body water isotopic variation the relatively thin enamel precludes problems associated with time averaging associated with complex growth patterns found in thick mammalian enamel the most consistent and striking pattern associated with all of the teeth are two relatively closely spaced subequal maxima these appear to be associated with onset of a seasonal episode of high humidity after the activation of the amount effect where the influence of ambient temperature on surface water and body water 18 o ends while temperatures remain above 20 c teeth within a single fossiliferous horizon show the same general isotopic pattern and range a notable difference in pattern shape and magnitude of isotopic variation between tyrannosaurid teeth from several stratigraphic intervals of the lower horseshoe canyon formation section indicates a climatic changes from strong seasonality high annual temperature range with distinct precipitation and humidity maxima during each year at the base of the section to milder seasonality at the top

palaeoecology and palaeoclimatic context of romanian carpathian mis 3 cave bears using stable isotopes δ13c and δ18o abstract millimeter scale growth rings in canine dentine of mis 3 cave bears have been interpreted as annual growth bands produced in part by seasonal variation in growth rate we present new intra tooth stable carbon 13c and oxygen 18o isotope profiles in dentine hydroxylapatite of early forming permanent teeth from three famous late pleistocene cave bear sites from romanian carpathians we measured 13c and 18o of the co3 fraction of dentine hydroxylapatite from samples covering a profile across the root representing a general line from juvenile period to adulthood carbon isotopes measured in dentine samples from the first to the last to be deposited of the same individual record an increase in 13c values throughout immature life of bears as has been shown previously with lower precision using age categories for the first time based on 13c data analysis the weaning process in cave bears was identified the 18o values show substantial variations related most probably to seasonal growth of the dentine finally the co3 of dentine apatite extracted from cave bear canines proves to be reliable for geochemical analyses reflecting physiology behavior and palaeoclimatic conditions

the preservation of glacial interglacial climatic signatures in the oxygen isotopes of elephant skeletal phosphate abstract phosphate 18o values 18op of modern elephant bone and teeth are found to vary linearly according to the 18o of local meteoric water 18omw a parameter with close ties to regional and local climatic conditions enamel dentine cementum and bone separates from individual fossil elephant specimens of late pleistocene age have op values which vary by up to elephant specimens the larger spread in the 18op values of the various skeletal phases for the fossil samples is interpreted as evidence for post depositional alterantion of primary 18op signatures of some if not all of these fossil skeletal components in the fossil samples investigated enamel and dentine phases have systematically lower 18o values than associated bone and cementum phases differential re equilibration with soil waters either by the wholesale replacement of primary apatite or by processes of isotopic exchange is suggested as a mechanism to account for the observed spread in the fossil phosphate 18o data

an ordovician ophiolite in county tyrone ireland ophiolites are regarded widely by geologists as remnants of old oceanic crust that has been obducted onto the continental margins during ocean or marginal basin closure and orogeny therefore they provide evidence for the existence of old oceans and oceanic basins and are a key to the extension of plate tectonic modelling into pre mesozoic rock assemblages in the caledonide appalachian orogen ophiolites are known although very few of these are dated well enough to provide accurate constraints on plate tectonic kinematics we report here the discovery of an ophiolitic sequence within the rocks of the tyrone igneous complex in northern ireland u pb dating combined with field evidence indicates that the tyrone ophiolite was formed and then obducted onto the northern margins of the iapetus ocean close to 470 myr bp arenig

bone as a stable isotope archive for local climatic information this brief review outlines the contribution that the study of stable isotope composition in bone can make to palaeoclimatic investigation with the focus almost entirely restricted to the last 50 000 years in nw europe bone can provide a useful archive of the prevailing isotopic condition and represents a quite different and often less specialised sampling of the environment than most other archives on the other hand chronological sequences and dating generally can be a problem and the link between the isotopic value registered in the bone and the environmental conditions which gave rise to it is both complex and not fully understood carbon oxygen and nitrogen isotopes are all available from bone nitrogen only where sufficient protein collagen survives and are all subject in different ways to climatic influences such as temperature rainfall changes in floristic composition and soil chemistry these are all briefly discussed and the datasets that are being published are considered in the context of the environmental information they provide undoubtedly environmental signals are recoverable but their interpretation is still primitive a dataset for carbon and nitrogen isotope composition of herbivores that spans the last 50 000 years is shown together with some of the issues it raises

petrology of the abloviak aillikite dykes new quebec evidence for a cambrian diamondiferous alkaline province in northeastern north america a dozen ultramafic lamprophyre dykes have been identified in the eastern part of ungava bay quebec the dark grey dykes are composed of macrocrysts of olivine and phlogopite featuring tetraferriphlogopite rims these minerals are included in a matrix consisting of fine grained phlogopite olivine spinel and interstitial carbonate the geochemical composition mineral assemblage chemical analyses of the xenocrysts and phenocrysts and sm nd isotopic signature indicate that these rocks are carbonated ultramafic lamprophyre dykes the chemical zonation of the micas and the presence of andradite suggest a complex sequence of crystallization an ar isotope correlation analysis indicates an age of approximately 550 ma the dykes have intruded the tasiuyak gneiss a suite of paleoproterozoic metasedimentary rocks this unit occupies the torngat orogen collision zone between the rae province and the nain province the dykes are considered to have been emplaced within tension gashes during reactivation of major