the role of ocean thermal expansion in last interglacial sea level rise 1 a compilation of paleoceanographic data and a coupled atmosphere ocean climate model were used to examine global ocean surface temperatures of the last interglacial lig period and to produce the first quantitative estimate of the role that ocean thermal expansion likely played in driving sea level rise above present day during the lig our analysis of the paleoclimatic data suggests a peak lig global sea surface temperature sst warming of 0 7 0 6 c compared to the late holocene our lig climate model simulation suggests a slight cooling of global average sst relative to preindustrial conditions sst 0 4 c with a reduction in atmospheric water vapor in the southern hemisphere driven by a northward shift of the intertropical convergence zone and substantially reduced seasonality in the southern hemisphere taken together the model and paleoceanographic data imply a minimal contribution of ocean thermal expansion to lig sea level rise above present day uncertainty remains but it seems unlikely that thermosteric sea level rise exceeded 0 4 0 3 m during the lig this constraint along with estimates of the sea level contributions from the greenland ice sheet glaciers and ice caps implies that 4 1 to 5 8 m of sea level rise during the last interglacial period was derived from the antarctic ice sheet these results reemphasize the concern that both the antarctic and greenland ice sheets may be more sensitive to temperature than widely thought

insolation values for the climate of the last 10 million years new values for the astronomical parameters of the earth s orbit and rotation eccentricity obliquity and precession are proposed for paleoclimatic research related to the late miocene the pliocene and the quaternary they have been obtained from a numerical solution of the lagrangian system of the planetary point masses and from an analytical solution of the poisson equations of the earth moon system the analytical expansion allows the direct determination of the main frequencies with their phase and amplitude numerical and analytical comparisons with the former astronomical solution ber78 are performed so that the accuracy and the interval of time over which the new solution is valid can be estimated the corresponding insolation values have also been computed this analysis leads to the conclusion that the new values are expected to be reliable over the last 5 ma in the time domain and at least over the last 10 ma in the frequency domain

evidence for warmer interglacials in east antarctic ice cores reconstructions of temperature variations from antarctic ice cores rely on the assumption that the relationship between hydrogen and oxygen isotopic ratios and temperature are stable in space and time sime et al analyse three 340 000 year old ice cores from east antarctica and use an isotope enabled general circulation model to show that instead the relationship is nonlinear during warm periods the ratios are less sensitive to temperature so previous estimates of interglacial temperatures are likely to be about 3 c too low this is consistent with peak antarctic interglacial temperatures at least 6 c higher than today this work suggests that there are serious deficiencies in our understanding of climates that are warmer than today s reconstructions of temperature variations from antarctic ice cores rely on the assumption that the relationship between hydrogen and oxygen isotope ratios and temperature are stable in space and time three east antarctic ice core records are now analysed alongside input from general circulation models to reveal that during warmer interglacial periods the isotope ratios are less sensitive to temperature than during colder interglacials consequently previous estimates of interglacial temperatures are probably too cold stable isotope ratios of oxygen and hydrogen in the antarctic ice core record have revolutionized our understanding of pleistocene climate variations and have allowed reconstructions of antarctic temperature over the past 800 000 years 800 kyr refs 1 2 the relationship between the d h ratio of mean annual precipitation and mean annual surface air temperature is said to be uniform 10 over east antarctica3 and constant with time 20 refs 3 5 in the absence of strong independent temperature proxy evidence allowing us to calibrate individual ice cores prior general circulation model gcm studies have supported the assumption of constant uniform conversion for climates cooler than that of the present day3 5 here we analyse the three available 340 kyr east antarctic ice core records alongside input from gcm modelling we show that for warmer interglacial periods the relationship between temperature and the isotopic signature varies among ice core sites and that therefore the conversions must be nonlinear for at least some sites model results indicate that the isotopic composition of east antarctic ice is less sensitive to temperature changes during warmer climates we conclude that previous temperature estimates from interglacial climates are likely to be too low the available evidence is consistent with a peak antarctic interglacial temperature that was at least 6 k higher than that of the present day approximately double the widely quoted 3 1 5 k refs 5 6

a novel method to estimate mineral compositions of mudrocks a case study for the canadian unconventional petroleum systems abstract the mineral composition of mudrocks is an essential attribute in controlling the reservoir quality of unconventional petroleum systems the present study introduces a semi quantitative method to estimate mineral phases of mudrocks in various canadian unconventional hydrocarbon systems using total elemental analysis inductively coupled plasma mass spectrometry icp ms and rock eval data total organic carbon toc and mineral carbon minc this method involves statistical analysis based on a sound knowledge of hydrocarbon source rock inorganic geochemistry the workflow can be divided into four steps i converting major elements si al fe k na ca mg ti and p to their oxides ii inferring modes of occurrence of elements using statistical analysis of geochemical data major elements toc and minc iii identifying the mineral types oxide aluminosilicates carbonates sulfide and phosphate according to elemental occurrences and calculating mineral phase concentrations and iv verifying the results by comparing to xrd data on selected samples the results especially for brittle minerals such as quartz carbonates e g calcite dolomite and ankerite and pyrite show that the estimated mineral compositions correspond closely and consistently with measured mineralogy obtained from xrd this method takes advantage of bulk geochemical data already available for hydrocarbon potential and chemostratigraphic studies without devoting additional samples and cost for xrd analysis

orbitally driven insolation forcing on holocene climate trends evidence from alkenone data and climate modeling a global spatial pattern of long term sea surface temperature sst trends over the last 7000 years is explored using a comparison of alkenone derived sst records with transient ensemble climate simulations with a coupled atmosphere ocean circulation model under orbitally driven insolation forcing the spatial trend pattern both in paleo sst data and in model results shows pronounced global heterogeneity generally the extratropics cooled while the tropics experienced a warming during the middle to late holocene we attribute these divergent holocene climate trends to seasonally opposing insolation changes furthermore climate mode changes similar to the arctic north atlantic oscillation are superimposed on the prevalent pattern it is concluded that nonlinear changes in the entire seasonal cycle of insolation played a dominant role for the temporal evolution of holocene surface temperatures for understanding of marine proxy data apart from the dominance of summer insolation in high latitudes a notable shift in the maximum insolation of the year in low latitudes has to be taken into account which may influence timing of phytoplankton production and thus alters the seasonal origin of temperature signals recorded in the proxies

recent changes 1991 2010 in glacier mass balance and air temperature in the european alps we estimate temperature sensitivity of observed mass balance for glaciers in the alps to compare with our earlier estimates from modelling we treat 1961 1990 as our reference period and compare mass balance for 1991 2010 with this reference period there are eight alpine glaciers with long enough records the mean mass balance for the eight glaciers is close to zero for the reference period very negative for 1991 2010 and highly negative in the exceptionally warm year 2003 mass balance changes are compared with 1991 2010 temperature anomalies to give an average temperature sensitivity of about 0 7 0 2 m w e a 1 k 1 for the eight glaciers there is considerable variation between individual glaciers with higher sensitivity for western glaciers and lower sensitivity for more eastern glaciers temperature sensitivity for the eight glaciers is strongly correlated with the standard deviation of observed mass balance which from earlier work is known to be correlated with winter balance the mean temperature sensitivity for observed mass balance is in reasonable agreement with values from earlier models but changes in glacier hypsometry during 1991 2010 may have further increased observed mass loss

temperature reconstruction from the length fluctuations of small glaciers in the eastern alps northeastern italy in this study a linear model computing the air temperature fluctuations from the measured glacier snout fluctuations has been applied for the first time to three small glaciers in the western tauern alps eastern alps in the period 1929 2011 the considered glaciers with areas between 0 2 and 1 3 hbox km 2 are characterized by relevant time variations of their morphology length and slope the model requires the knowledge of two parameters the glacier climate sensitivity c s and the glacier response time tau both depending on the glacier morphological characteristics and on the precipitation applied to the glaciers assuming c s and tau as in the original formulation it underestimates the temperature increase of approx 1 8 circ hbox c derived over the whole period from the in situ data given the characteristics of these small glaciers these parameters have been recalibrated by means of a non linear least square regression using an independent set of glaciers their mean value is of about 210 m k and 3 8 years respectively with the recalibrated values of the new glacier climate sensitivity c s and response time tau the temperature fluctuations derived by the model reproduce well those obtained from the observed temperatures computed over the hydrological year with linear correlations between 0 8 and 0 9 the increase of the modeled mean temperature over the whole period fits in with that derived from observed temperature considering that the length fluctuations of these small glaciers affect significantly their slope and length we tested the impact in the model of a time dependent formulation of c s and tau the results indicate slight improvements both in the values of the correlation between the reconstructed and the observed temperature fluctuations and in the global temperature increase given the above value of climate sensitivity the large retreat of the small alpine glaciers threatens their survival within a few decades but the morphological changes in progress may counteract the glacier disappearance

epica dome c record of glacial and interglacial intensities abstract climate models show strong links between antarctic and global temperature both in future and in glacial climate simulations past antarctic temperatures can be estimated from measurements of water stable isotopes along the epica dome c ice core over the past 800 000 years here we focus on the reliability of the relative intensities of glacial and interglacial periods derived from the stable isotope profile the consistency between stable isotope derived temperature and other environmental and climatic proxies measured along the edc ice core is analysed at the orbital scale and compared with estimates of global ice volume mis 2 12 and 16 appear as the strongest glacial maxima while mis 5 5 and 11 appear as the warmest interglacial maxima the links between edc temperature global temperature local and global radiative forcings are analysed we show i a strong but changing link between edc temperature and greenhouse gas global radiative forcing in the first and second part of the record ii a large residual signature of obliquity in edc temperature with a 5 ky lag iii the exceptional character of temperature variations within interglacial periods focusing on mis 5 5 the warmest interglacial of edc record we show that orbitally forced coupled climate models only simulate a precession induced shift of the antarctic seasonal cycle of temperature while they do capture annually persistent greenland warmth models fail to capture the warming indicated by antarctic ice core d we suggest that the model data mismatch may result from the lack of feedbacks between ice sheets and climate including both local antarctic effects due to changes in ice sheet topography and global effects due to meltwater thermohaline circulation interplays an mis 5 5 sensitivity study conducted with interactive greenland melt indeed induces a slight antarctic warming we suggest that interglacial edc optima are caused by transient heat transport redistribution comparable with glacial north south seesaw abrupt climatic changes

high resolution carbon isotope records of the toarcian oceanic anoxic event early jurassic from north america and implications for the global drivers of the toarcian carbon cycle the mesozoic era experienced several instances of abrupt environmental change that are associated with instabilities in the climate reorganizations of the global carbon cycle and elevated extinction rates often during these perturbations oxygen deficient conditions developed in the oceans resulting in the widespread deposition of organic rich sediments these events are referred to as oceanic anoxic events or oaes such events have been linked to massive injections of greenhouse gases into the ocean atmosphere system by transient episodes of voluminous volcanism and the destabilization of methane clathrates within marine environments nevertheless uncertainty surrounds the specific environmental drivers and feedbacks that occurred during the oaes that caused perturbations in the carbon cycle this is particularly true of the early jurassic toarcian oae 183 1 ma here we present biostratigraphically constrained carbon isotope data from western north america alberta and british columbia canada to better assess the global extent of the carbon cycle perturbations we identify the large negative carbon isotope excursion associated with the oae along with high frequency oscillations and steps within the onset of this excursion we propose that these high frequency carbon isotope excursions reflect changes to the global carbon cycle and also that they are related to the production and release of greenhouse gases from terrestrial environments on astronomical timescales furthermore increased terrestrial methanogenesis should be considered an important climatic feedback during ocean anoxic events and other similar events in earth history after the proliferation of land plants

simulating arctic climate warmth and icefield retreat in the last interglaciation in the future arctic warming and the melting of polar glaciers will be considerable but the magnitude of both is uncertain we used a global climate model a dynamic ice sheet model and paleoclimatic data to evaluate northern hemisphere high latitude warming and its impact on arctic icefields during the last interglaciation our simulated climate matches paleoclimatic observations of past warming and the combination of physically based climate and ice sheet modeling with ice core constraints indicate that the greenland ice sheet and other circum arctic ice fields likely contributed 2 2 to 3 4 meters of sea level rise during the last interglaciation

a new ammonite and coccolith fauna from the lowermost fernie formation hettangian in northwestern alberta canada the occurrence of the ammonite discamphiceras cf silberlingi guex in a core 25 cm above the base of dark bituminous shales of the lowermost fernie formation in the subsurface of northwestern alberta establishes their middle to late hettangian age associated coccoliths suggest a possible late hettangian to early sinemurian age which is the oldest so far assigned to these shales and differs considerably from both the sinemurian age of the type nordegg member of the outcrop belt and the pliensbachian age of its supposed basinal equivalents nordegg member of some recent authors

update of the carbon and oxygen isotopic records of the early late pliensbachian early jurassic 187ma insights from the organic rich hemipelagic series of the lusitanian basin portugal abstract a high resolution carbon and oxygen isotopic bulk carbonate record from organic rich hemipelagic series of early late pliensbachian age 187 ma is presented for the lusitanian basin portugal and compared to the record of other sedimentary basins this dataset provides an excellent basis for discussing newly raised questions concerning the hypothesis of major carbon cycle perturbations prior to the toarcian oceanic anoxic event in addition to the recognition in the studied series of two positive carbon isotope excursions previously defined elsewhere corresponding to the ibex and margaritatus uppermost stokesi gibbosus subzones zones a third positive excursion is identified here for the first time at the davoei zone in the lusitanian basin these excursions are associated with organic rich facies intervals the younger excursion may be related to worldwide enhanced preservation of organic matter in the margaritatus zone we suggest that until these organic rich facies are well age constrained at a wider scale and high resolution carbon data are provided from other locations and that worldwide anoxia is proven this interval should be referred to as an organic matter preservation interval late pliensbachian ompi this period is probably linked with the complex chain of events that eventually led to the toarcian oceanic anoxic event

regional and global volumes of glaciers derived from statistical upscaling of glacier inventory data 1 very few global scale ice volume estimates are available for mountain glaciers and ice caps although such estimates are crucial for any attempts to project their contribution to sea level rise in the future we present a statistical method for deriving regional and global ice volumes from regional glacier area distributions and volume area scaling using glacier area data from 123 000 glaciers from a recently extended world glacier inventory we compute glacier volumes and their sea level equivalent sle for 19 glacierized regions containing all mountain glaciers and ice caps on earth on the basis of total glacierized area of 741 103 68 103 km2 we estimate a total ice volume of 241 103 29 103 km3 corresponding to 0 60 0 07 m sle of which 32 is due to glaciers in greenland and antarctica apart from the ice sheets however our estimate is sensitive to assumptions on volume area scaling coefficients and glacier area distributions in the regions that are poorly inventoried i e antarctica north america greenland and patagonia this emphasizes the need for more volume observations especially of large glaciers and a more complete world glacier inventory in order to reduce uncertainties and to arrive at firmer volume estimates for all mountain glaciers and ice caps

planktonic foraminiferal assemblages preserved in surface sediments correspond to multiple environment variables abstract here we investigate the relationships between modern planktonic foraminiferal species assemblages from atlantic and pacific core top sediment samples and 35 water column and preservation properties using canonical correspondence analysis cca cca finds two faunal dimensions axes that are most highly correlated to the environmental variables and describes each axis in terms of the best linear combination of environmental variables cca axis 1 30 4 of the faunal variance is related primarily to mean annual sea surface temperature sst r 0 96 cca axis 2 7 9 of the faunal variance is related to environmental variability associated with an inverse relationship between sst and surface salinity as well as pycnocline phosphate concentrations the seasonal range in nitrate concentrations water depth and chlorophyll concentrations at the sea surface based on this clustering of nutrient and chlorophyll on axis 2 we infer an ecological response to oceanic fertility no evidence is found for a unique dissolution influence suggesting that sea floor carbonate ion concentration cannot be estimated reliably from planktonic foraminiferal assemblages our results support the use of foraminiferal assemblages to estimate mean annual sst

western arabian sea sst during the penultimate interglacial a comparison of u37k and mg ca paleothermometry millennial scale records of planktonic foraminiferal mg ca bulk sediment u37 k and planktonic foraminiferal 18o are presented across the last two deglaciations in sediment core niop929 from the arabian sea mg ca derived temperature variability during the penultimate and last deglacial periods falls within the range of modern day arabian sea temperatures which are influenced by monsoon driven upwelling the u37 k derived temperatures in mis 5e are similar to modern intermonsoon values and are on average 3 5 c higher than the mg ca temperatures in the same period mis 5e u37 k and mg ca temperatures are 1 5 c warmer than during the holocene while the u37 k mg ca temperature difference was about twice as large during mis 5e this is surprising as nowadays both proxy carriers have a very similar seasonal and depth distribution partial explanations for the mis 5e u37 k mg ca temperature offset include carbonate dissolution the change in dominant alkenone producing species and possibly lateral advection of alkenone bearing material and a change in seasonal or depth distribution of proxy carriers our findings suggest that 1 mg ca of g ruber documents seawater temperature in the same way during both studied deglaciations as in the present with respect to e g season and depth and 2 u37 k based temperatures from mis 5 or older represent neither upwelling sst nor annual average sst as it does in the present and the holocene but a higher temperature despite alkenone production mainly occurring in the upwelling season further we report that at the onset of the deglacial warming the mg ca record leads the u37 k record by 4 ka of which a maximum of 2 ka may be explained by postdepositional processes deglacial warming in both temperature records leads the deglacial decrease in the 18o profile and mg ca based temperature returns to lower values before 18o has reached minimum interglacial values this indicates a substantial lead in arabian sea warming relative to global ice melting

new lower jurassic ammonite faunas from the fernie formation southern canadian rocky mountains new ammonite faunas are described from sections along bighorn and scalp creeks in central western alberta where lower jurassic parts of the fernie formation are exposed the first record of the upper sinemurian obtusum zone from the fernie is based on the occurrence of asteroceras cf stellare and epophioceras cf breoni in the basal pebbly coquina on bighorn creek the overlying red deer member has yielded amaltheus cf stokesi representing the upper pliensbachian margaritatus zone in immediately superjacent strata the first north american examples of amauroceras occur together with protogrammoceras and aveyroniceras in the basal parts of the overlying poker chip shale a fauna including harpoceras cf falciferum harpoceratoides polyplectus cf subplanatus hildaites cf serpentiniformis and dactylioceras cf athleticum is correlated with the lower toarcian falciferum zone the upper parts of the poker chip shale on fording river in southeastern british columbia contain a fauna representing some pa

modelling of hydrological response to climate change in glacierized central asian catchments the arid lowlands of central asia are highly dependent on the water supplied by the tien shan mountains snow and ice storage make large contributions to current runoff particularly in summer two runoff models with different temporal resolutions hbv eth and oez were applied in three glaciated catchments of the tien shan mountains scenario runs were produced for a climate change caused by the doubling of atmospheric co2 as predicted by the giss global circulation model and assuming a 50 reduction of glaciation extent as well as a complete loss of glaciation agreement of the results was best for runs based on 50 glaciation loss where both models predict an increase in spring and summer runoff compared to current levels scenarios for complete loss of glaciation predict an increase in spring runoff levels followed by lower runoff levels for july and august model predictions differ concerning the degree of reduction of late summer runoff these scenarios are sensitive to model simulation of basin precipitation as well as to reduction of glaciation extent

the last interglacial ocean the final effort of the climap project was a study of the last interglaciation a time of minimum ice volume some 122 000 yr ago coincident with the substage 5e oxygen isotopic minimum based on detailed oxygen isotope analyses and biotic census counts in 52 cores across the world ocean last interglacial sea surface temperatures sst were compared with those today there are small sst departures in the mid latitude north atlantic warmer and the gulf of mexico cooler the eastern boundary currents of the south atlantic and pacific oceans are marked by large sst anomalies in individual cores but their interpretations are precluded by no analog problems and by discordancies among estimates from different biotic groups in general the last interglacial ocean was not significantly different from the modern ocean the relative sequencing of ice decay versus oceanic warming on the stage 6 5 oxygen isotopic transition and of ice growth versus oceanic cooling on the stage 5e 5d transition was also studied in most of the southern hemisphere the oceanic response marked by the biotic census counts preceded led the global ice volume response marked by the oxygen isotope signal by several thousand years the reverse pattern is evident in the north atlantic ocean and the gulf of mexico where the oceanic response lagged that of global ice volume by several thousand years as a result the very warm temperatures associated with the last interglaciation were regionally diachronous by several thousand years these regional lead lag relationships agree with those observed on other transitions and in long term phase relationships they cannot be explained simply as artifacts of bioturbational translations of the original signals

last interglacial arctic warmth confirms polar amplification of climate change the warmest millennia of at least the past 250 000 years occurred during the last interglaciation when global ice volumes were similar to or smaller than today and systematic variations in earth s orbital parameters aligned to produce a strong positive summer insolation anomaly throughout the northern hemisphere the average insolation during the key summer months m j j was ca 11 above present across the northern hemisphere between 130 000 and 127 000 years ago with a slightly greater anomaly 13 over the arctic greater summer insolation early penultimate deglaciation and intensification of the north atlantic drift combined to reduce arctic ocean sea ice allow expansion of boreal forest to the arctic ocean shore across vast regions reduce permafrost and melt almost all glaciers in the northern hemisphere insolation amplified by key boundary condition feedbacks collectively produced last interglacial summer temperature anomalies 4 5 c above present over most arctic lands significantly above the average northern hemisphere anomaly the last interglaciation demonstrates the strength of positive feedbacks on arctic warming and provides a potentially conservative analogue for anticipated future greenhouse warming

calibration of mg ca thermometry in planktonic foraminifera from a sediment trap time series 1 paired mg ca and 18o measurements on planktonic foraminiferal species g ruber white g ruber pink g sacculifer g conglobatus g aequilateralis o universa n dutertrei p obliquiloculata g inflata g truncatulinoides g hirsuta and g crassaformis from a 6 year sediment trap time series in the sargasso sea were used to define the sensitivity of foraminiferal mg ca to calcification temperature habitat depths and calcification temperatures were estimated from comparison of 18o of foraminifera with equilibrium calcite based on historical temperature and salinity data when considered together mg ca mmol mol of all species except two show a significant r 0 93 relationship with temperature t c of the form mg ca 0 38 0 02 exp 0 090 0 003 t equivalent to a 9 0 0 3 change in mg ca for a 1 c change in temperature small differences exist in calibrations between species and between different size fractions of the same species o universa and g aequilateralis have higher mg ca than other species and in general data can be best described with the same temperature sensitivity for all species and pre exponential constants in the sequence o universa g aequilateralis g bulloides g ruber g sacculifer other species this approach gives an accuracy of 1 2 c in the estimation of calcification temperature the 9 sensitivity to temperature is similar to published studies from culture and core top calibrations but differences exist from some literature values of pre exponential constants different cleaning methodologies and artefacts of core top dissolution are probably implicated and perhaps environmental factors yet understood planktonic foraminiferal mg ca temperature estimates can be used for reconstructing surface temperatures and mixed and thermocline temperatures using g ruber pink g ruber white g sacculifer n dutertrei p obliquiloculata etc the existence of a single mg thermometry equation is valuable for extinct species although use of species specific equations will where statistically significant provide more accurate evaluation of mg ca paleotemperature

new biostratigraphic data from the lower jurassic fernie formation in the subsurface of west central alberta and their stratigraphic implications geophysical gamma ray log responses and examination of cores from select wells of the lower fernie formation document important correlations of several new lithologic units recognized in the subsurface of west central alberta ammonite faunas and coccolith floras recovered from these cores are illustrated and provide new ages for several of these units requiring a revision of their correlation with surface stratigraphy of the west central alberta foothills the organic rich fine grained west central alberta subsurface lower fernie formation sediments are hettangian to late toarcian in age and are therefore correlative with outcrops of unnamed basal fernie strata of northeastern british columbia nordegg member cherty limestones of the cadomin and nordegg areas and with the red deer member and poker chip shale at outcrop in west central alberta

high resolution characterization of a core from the lower jurassic gordondale member western canada sedimentary basin abstract the gordondale member is a hydrocarbon source rock and potential unconventional reservoir that extends across northeastern british columbia and central northwestern alberta it is an organic rich calcareous fossiliferous mudstone with a median total organic carbon value of 6 0 wt a total of 230 samples were collected from approximately 25 m of gordondale member core for organic matter analysis using rock eval 6 analysis and organic petrology detailed core logging provides sedimentological context for organic matter characterization the predominant organic material in the samples is solid bitumen and liptinite with lesser zooclast and inertinite most kerogen is type ii autochthonous marine biomass with minimal dilution by inert organic carbon rock eval tmax values and random reflectance measurements of solid bitumen indicate the samples are within the oil generation window solid bitumen contributes a substantial amount of hydrocarbon potential to the interval a micro reservoir structure within the core is produced by thin intervals of impermeable displacive calcite that act as barriers to the upward migration of free hydrocarbons these free hydrocarbon accumulations could make excellent targets for horizontal wells within the gordondale member

response of macrobenthic communities to the toarcian oceanic anoxic event in northeastern panthalassa ya ha tinda alberta canada abstract in the early jurassic the late pliensbachian through early toarcian interval exhibits significant environmental perturbations and biotic extinctions this study documents the macrobenthic community during this interval in a region that has previously received comparatively little study northeastern panthalassa the relicts of benthic communities from the ya ha tinda lagerstatte fernie formation in alberta canada are primarily composed of bivalves and brachiopods and exhibit taxonomic and ecological similarities with coeval black shale faunas from europe at ya ha tinda the initiation of the carbon isotope excursion that occurred during the toarcian oceanic anoxic event t oae is coincident with major faunal change the pre t oae community is composed of large epifaunal suspension feeders bivalves and brachiopods lobsters crinoids and burrowing organisms represented as trace fossils the onset of the isotope excursion coincided with a wholesale turnover of bivalve and brachiopod genera as well as with a significant diminution in body size of the community members as a whole the intra t oae community largely consisted of opportunistic low oxygen tolerant benthic taxa that colonized the seafloor periodically along with some facultatively pseudoplanktonic taxa unlike the contemporary deposits in europe there is no sign of recovery at ya ha tinda in the middle toarcian planulata ammonite zone abundance richness and functional diversity of benthic taxa remained extremely low and the size of community members remained small the primary stress on this system is interpreted to have been oxygen limitation the minimal ecological effect on the benthic community at the pliensbachian toarcian stage boundary and delayed recovery from the t oae of the benthos are in marked contrast to the pelagic record from northeastern panthalassa this suggests a decoupling of the benthic and pelagic communities in this region during the early jurassic

high precision reos dating of lower jurassic shale packages from the western canadian sedimentary basin abstract the lower jurassic rock record contains abundant organic rich mudrocks suitable for refining early jurassic time using re os organic rich shale ors geochronometry such as those associated with the sinemurian pliensbachian boundary event or the toarcian ocean anoxic event t oae despite this most studies to date have failed to obtain high precision geologically meaningful ages for such lower jurassic rocks the cause of imprecision in re os ors age dates at least for the toarcian has been linked to subtle chemostratigraphic variations in 187os 188osi values here we report the first high precision re os ages of organic rich shale packages of the gordondale and basal poker chip members of the lower jurassic fernie formation of northwestern alberta canada from the western canadian sedimentary basin wcsb our re os age results bracket sediment deposition between the late sinemurian early pliensbachian 192 11 0 77 ma 2 and 193 83 1 34 ma 2 and late toarcian 180 10 2 68 ma 2 when coupled with chemo 87sr 86sr and 187os 188os isotopes and bio stratigraphy ammonite and coccolith our re os ages correlate with regional and global stratigraphic tie points corresponding to pivotal points of early jurassic time such as the sinemurian pliensbachian boundary event t oae and late toarcian that are otherwise weakly constrained by isotopic methods this integrative approach helps to place these events in a more robust temporal framework based on seawater os isotope data we also speculate that a previously unidentified positive os isotope excursion exists at the sinemurian pliensbachian boundary perhaps triggered by late stage central atlantic magmatic province camp volcanism

liquid water storage in snow and ice in 86 eastern alpine basins and its changes from 1970 97 to 1998 2006

report of 1st discussion group the last interglacial in high latitudes of the northern hemisphere terrestrial and marine evidence abstract the paleoclimatic informations preserved at some selected sites from high northern latitudes correlative with the last interglacial maximum of isotopic substage 5e have been compiled on a hemisphere scale the mapped compilation reveals much warmer climate conditions on average than present in both terrestrial and marine environments and indicates a northward shift of subpolar and boreal bioclimatic zones the data also suggest that temperature and precipitation gradients were significantly different than those of the holocene with particularly efficient latitudinal and eastward transport of warm air masses the paleoenvironmental and paleoclimate trends through the last interglacial sensu lato isotopic stage 5 are more difficult to assess because the chronostratigraphical framework is poorly constrained nevertheless the data suggest important regionalism in the climatostratigraphical trends in particular the large amplitude climatic cyclicity that characterizes the last interglacial of europe is barely observed elsewhere moreover by the end of the last interglacial isotopic substage 5a conditions slightly cooler than present are recorded in western europe while relatively warm conditions similar to today apparently prevailed in circumpolar regions adjacent to the north atlantic despite the onset of ice growth the last interglacial provides paleosynoptic situations unlike those of the present that may contribute to understanding interactions within the environmental system on a hemispheric scale there is however an imperative need for uniformization of data sets and for more accurate chronological control on regional scales

new biostratigraphically significant ammonites from the jurassic fernie formation southern canadian rocky mountains jurassic ammonites described here for the first time come from numerous localities in the fernie formation in the foothills and front ranges of the rocky mountains of north and south eastern british columbia and central and south western alberta and provide useful new age data for several members of the formation the occurrence of orthodactylites sp in the uppermost beds of the red deer member indicates this unit extends upwards into the basal toarcian which will be helpful in the search for carbon isotope excursions associated with the early toarcian anoxic event the presence of hettangian and lower pliensbachian strata in outcrop of the gordondale member is confirmed diversity of the ammonite fauna in the grey beds is enlarged by the presence of kepplerites cadomites and choffatia spp these faunas also provide biostratigraphic constraints for carbon and oxygen isotope trends and u pb ages recently recorded from the highwood member and grey beds exposed in bighorn creek and its eastern tributary and in fording river the first occurrence of zemistephanus richardsoni from cratonic rocks recorded here suggests close proximity of the allochthonous terranes wrangellia and stikinia the only other areas from which this species is known to the northwest north american craton by early bajocian time one new species cardioceras subvertebriceras ferniensis is described

different magnitudes of projected subsurface ocean warming around greenland and antarctica accurate projections of global sea level rise require information of future ocean warming in the vicinity of the large ice sheets an analysis of 19 climate model projections suggests that subsurface ocean warming near both polar ice sheets will be substantial with the potential to lead to significant increases in ice mass loss