sedimentology and stratigraphy of thetownsend tuff bed lower old red sandstone in south wales and the welsh borders the townsend tuff bed has a highly distinctive internal stratigraphy which allows it to be recognized at a large number of localities scattered over the welsh borders and south wales it is a group of 3 almost directly superimposed normally graded air fall tuffs that originated in distant but powerful plinian eruptions centre unknown and became spread over extensive but practically featureless coastal mud flats the bed occurs in a barren interval within the early lower old red sandstone between a silurian invertebrate vertebrate fauna below and an already devonian vertebrate assemblage above the base of the devonian system in south wales and the welsh borders is accordingly defined as occurring at a regionally uniform lithological contact within the townsend tuff bed

major pathways of atlantic water in the northern north atlantic and nordic seas toward arctic 1 the major pathways of near surface atlantic water in the northern north atlantic and nordic seas are identified as current speeds above 30 cm s using 1014 lagrangian drifters combined with previously published hydrography the inflow over the scotland greenland ridge and establishment of the two branch norwegian atlantic current nwac are described in light of the circulation in the northern north atlantic the western branch of the nwac appears as a jet in the polar front topographically guided from the iceland faroe front through the nordic seas toward fram strait the eastern branch starts as a shelf edge current above the irish scottish continental shelf and after passing through the faroe shetland channel it continues northward along the norwegian shelf edge toward the arctic with a branch bifurcating into the barents sea the nwac appears to maintain its two branch structure throughout the nordic seas with the atlantic water confined to a 200 600 km wide wedge

spherulites in calcrete laminar crusts biogenic caco 3 precipitation as a major contributor to crust formation abstract spherulites calcitic fibro radial spherulitic polycrystals are a major component of calcite layers in quaternary calcrete laminar crusts to explain the formation of spherulites petrographic and chemical studies were performed on pleistocene calcrete laminar crusts holocene biological crusts and laboratory in vitro cultures of cyanobacterial strains spherulites were found to be formed of acicular and radiating crystals either smooth and regular edged or twisted and irregular edged spherulites were composed of low mg calcite the concentration of mg in the spherulites increasing from nucleus to periphery the shape and chemistry of the in vitro spherulites and laminar crust spherulites were identical the structure elementary crystal shape and size of spherul tes can be used to differentiate them from microcodium with which they are commonly confused in the literature spherulite genesis can be linked to cyanobacterial activity involving photosynthetic uptake of hco 3 leading to caco3 precipitation the bicarbonate causing release of equivalent amounts of oh in the mucilaginous sheath the main steps in cyanobacteria biomineralization producing spherulites are 1 uptake of co2 and or hco 3 from the medium as the inorganic carbon source for photosynthesis 2 release of oh in the sheath 3 carbonate ion formation resulting from the reaction of oh and hco 3 followed by 4 caco3 precipitation this process involves two steps in desert environments during dry spells the cyanobacterial mat calcifies leading to spherulite production and the fo mation of thin clear microsparitic layers during wet periods a thin sedimentary deposit forms mixing micrite detrital particles and inherited or new tiny spherulites with the mucilaginous mat of cyanobacteria which traps all of this material an organo micritic layer forms during the following dry spell the process is repeated and the laminar crust is formed in conclusion the presence of spherulites in the laminar crust is indicative of subaerial exposure the crust being a terrestrial stromatolite

paleopedology and stable isotope chemistry of late silurian vertic paleosols bloomsburg formation central pennsylvania abstract paleosols with vertic vertisol like features occur in repetitively stacked fining upward sequences bounded by marine erosional surfaces in the bloomsburg formation ludlovian to pridolian of central pennsylvania paleosol development was strongly influenced by repeated changes in relative sea level which resulted in subaerial exposure and pedogenesis of marginal marine sediment accumulating along a low energy mud dominated coastline in a delta plain environment bloomsburg paleosols are characterized by very weak horizonation abundant pedogenic slickensides and a micromorphology dominated by sepic fabrics and peds bounded by stress cutans pedogenic carbonate is sparse occurring principally as micrite nodules stable carbon isotope compositions of stratigraphically low pedogen c carbonate mean 13c 1 92 pdb are attributed to pedogenesis proximal to a marine coastline in stratigraphically high paleosols showing evidence of rhizolith development isotopic compositions of pedogenic carbonate suggest a significant contribution of carbon from c3 flora atmospheric p co2 levels estimated for these calcretes 4500 5500 ppmv are significantly greater than present day values low 18o values for pedogenic carbonate mean 18o 12 12 pdb record isotopic exchange between paleosol carbonate and 18o enriched fluids associated with the conversion of original soil smectites to illite and chlorite during burial diagenesis paleosols bounded by marine erosional surfaces show variable degrees of marine hydromorphism attributable to rising water table during transgression evidence for hydromorphism includes extensive reduction of iron as well as relative increases in cao mno mgo p2o5 na2o and sr at the tops of paleosols due to introduction of marine fluids and sediment into open soil fractures and burrows the abundance of vertic features in all bloomsburg paleosols by analogy with holocene vertisols indicates the recurrence of a seasonally wet dry dry 4 8 months year paleoclimate n the central appalachian region at a paleolatitude of about 20 south

the stable isotopic composition of modern soil carbonate and its relationship to climate the oxygen isotopic composition of modern soil carbonate is well correlated with the isotopic composition of local meteoric water the carbon isotopic cycle for co 2 in soils can be described in terms of the proportion of biomass using the c 4 photosynthetic pathway and the co 2 respiration rate of the soil at low soil respiration rates significant atmospheric co 2 mixing can occur in general the carbon isotopic composition of soil carbonate is related to the proportion of c 4 biomass present in soil but soils that freeze to the depth of carbonate formation often have a significant atmospheric component this suggests that freezing of the soil solution should be considered as another important mechanism for soil carbonate formation because of these relationships the isotopic composition of soil carbonate may be a paleoclimatic and paleoecologic indicator in cases in which diagenetic alteration has not occurred

surface climate variations over the north atlantic ocean during winter 1900 1989 abstract the low frequency variability of the surface climate over the north atlantic during winter is described using 90 years of weather observations from the comprehensive ocean atmosphere data set results are based on empirical orthogonal function analysis of four components of the climate system sea surface temperature sst air temperature wind and sea level pressure an important mode of variability of the wintertime surface climate over the north atlantic during this century is characterized by a dipole pattern in ssts and surface air temperatures with anomalies of one sign cast of newfoundland and anomalies of the opposite polarity off the southeast coast of the united states wind fluctuations occur locally over the regions of large surface temperature anomalies with stronger than normal winds overlying cooler than normal ssts this mode exhibits variability on quasi decadal and biennial time scales the decadal fluctuations are irregular in length averaging 9 years before 1945 and 1

short paper low grade metamorphism of the welsh basin lower palaeozoic succession an example of diastathermal metamorphism the lower palaeozoic succession of the welsh basin has suffered the effects of low grade metamorphism which shows features that do not accord with classical models of regional or burial metamorphism textural evidence demonstrates the development of greenschist facies metamorphism prior to deformation and cleavage development while mineralogical characters indicate a low pressure facies series in order to accommodate these features it is suggested that the area has suffered diastathermal metamorphism in which an enhanced thermal flux develops early in the tectonic cycle in response to an extensional setting temperatures remained relatively high during final closure associated with deformation of the basin sediments and consequent cleavage development such a model adequately resolves previously conflicting interpretations of burial and deformation related metamorphism

shifting surface currents in the northern north atlantic ocean 1 analysis of surface drifter tracks in the north atlantic ocean from the time period 1990 to 2007 provides evidence that warm subtropical waters have recently increased their penetration toward the nordic seas prior to 2000 the warm water branches of the north atlantic current fed by the gulf stream turned southeastward in the eastern north atlantic since 2001 these paths have shifted toward the rockall trough through which the most saline north atlantic waters pass to the nordic seas these surface drifters are able to overcome the ekman drift which would force them southward under the westerly winds dominating the subpolar atlantic yet the changes in path cannot be accounted for by changes in ekman drift eddy kinetic energy from satellite altimetry shows increased energy along the shifted drifter pathways across the mid atlantic ridge since 2001 these near surface changes have occurred during continual weakening of the north atlantic subpolar gyre as seen by altimetry they are also consistent with the observed increase in temperature and salinity of the waters flowing northward into the nordic seas these findings suggest the changes in the vertical structure of the northern north atlantic ocean its dynamics and exchanges with the higher latitudes wind stress and its curl changes are discussed as a possible forcing of the changes in the pathways of the subtropical waters

phanerozoic atmospheric co2 change evaluating geochemical and paleobiological approaches abstract the theory and use of geochemical modeling of the long term carbon cycle and four paleo pco 2 proxies are reviewed and discussed in order to discern the best applications for each method geochemical models provide pco 2 predictions for the entire phanerozoic but most existing models present 5 10 m y means and so often do not resolve short term excursions error estimates based on sensitivity analyses range from 75 200 ppmv for the tertiary to as much as 3000 ppmv during the early paleozoic the 13 c of pedogenic carbonates provide the best proxy based pco 2 estimates for the pre tertiary with error estimates ranging from 500 1000 ppmv pre devonian estimates should be treated cautiously error estimates for tertiary reconstructions via this proxy are higher than other proxies and models 400 500 ppmv and should not be solely relied upon we also show the importance of measuring the 13 c of coexisting organic matter instead of inferring its value from marine carbonates the 13 c of the organic remains of phytoplankton from sediment cores provide high temporal resolution up to 10 3 10 4 year high precision 25 100 ppmv for the tertiary to 150 200 ppmv for the cretaceous pco 2 estimates that can be near continuous for most of the tertiary its high temporal resolution and availability of continuous sequences is advantageous for studies aiming to discern short term excursions this method however must correct for changes in growth rate and oxygen level at elevated pco 2 750 1250 ppmv this proxy loses its sensitivity and is not useful the stomatal density and stomatal index of land plants also provide high temporal resolution 2 year high precision 10 40 ppmv for the tertiary and possibly cretaceous pco 2 estimates and so also is ideal for discerning short term excursions unfortunately this proxy also loses sensitivity at some level of pco 2 above 350 ppmv which currently is largely undetermined our analysis of the recently developed 11 b technique shows that it currently is not yet well constrained most importantly it requires the assumption that the boron isotopic composition of the ocean remains nearly constant through time in addition it assumes that there are no biological or temperature effects and that diagenetic alteration of the boron isotopic composition does not occur a fifth co 2 proxy based on the redox chemistry of marine cerium has several fundamental flaws and is not discussed in detail here

the transient atmospheric circulation response to north atlantic sst and sea ice anomalies abstract the objective of this study is to investigate the transient evolution of the wintertime atmospheric circulation response to imposed patterns of sst and sea ice extent anomalies in the north atlantic sector using a large ensemble of experiments with the ncar community climate model version 3 ccm3 the initial adjustment of the atmospheric circulation is characterized by an out of phase relationship between geopotential height anomalies in the lower and upper troposphere localized to the vicinity of the forcing this initial baroclinic response reaches a maximum amplitude in 5 10 days and persists for 2 3 weeks diagnostic results with a linear primitive equation model indicate that this initial response is forced by diabatic heating anomalies in the lower troposphere associated with surface heat flux anomalies generated by the imposed thermal forcing following the initial baroclinic stage of adjustment the response becomes progressively more barotropic and increases in both spatial extent an

carbon isotopic evidence for organic matter oxidation in soils of the old red sandstone silurian to devonian south wales uk petrographic and calcrete carbon isotope data from seasonally waterlogged upper silurian p idoli to lower devonian pragian palaeo vertisols of the old red sandstone south wales uk are presented the 13 c values mostly range from 9 to 12 vpdb suggesting that the soils were inhabited by abundant vegetation that when oxidized perhaps with microbial assistance resulted in co 2 rich soils such soils would favour calcrete precipitation through equilibration of soil zone co 2 with the relatively lower atmospheric p co 2 however reliably estimating palaeoatmospheric p co 2 using these carbon isotope data is a challenge supplementary material detailed information on stable isotope measurement methods descriptions of the samples and carbon and oxygen isotope data are available at www geolsoc org uk sup18754

reversal of the 1960s to 1990s freshening trend in the northeast north atlantic and nordic seas hydrographic time series in the northeast north atlantic and nordic seas show that the freshening trend of the 1960s 1990s has completely reversed in the upper ocean since the 1990s temperature and salinity have rapidly increased in the atlantic inflow from the eastern subpolar gyre to the fram strait in 2003 2006 salinity values reached the previous maximum last observed around 1960 and temperature values exceeded records the mean properties of the atlantic inflow decrease northwards but variations seen in the eastern subpolar gyre at 57 n persist with the same amplitude and pattern along the pathways to fram strait time series correlations and extreme events suggest a time lag of 3 4 years over that distance this estimate allows predictions to be made the temperature of atlantic water in the fram strait may start to decline in 2007 or 2008 salinity a year later but both will remain high at least until 2010

variability along the atlantic water pathway in the forced norwegian earth system model the growing attention on mechanisms that can provide predictability on interannual to decadal time scales makes it necessary to identify how well climate models represent such mechanisms in this study we use a high 0 25 horizontal grid and a medium 1 resolution version of a forced global ocean sea ice model utilising the norwegian earth system model to assess the impact of increased ocean resolution our target is the simulation of temperature and salinity anomalies along the pathway of warm atlantic water in the subpolar north atlantic and the nordic seas although the high resolution version has larger biases in general at the ocean surface the poleward propagation of thermohaline anomalies is better resolved in this version i e the time for an anomaly to travel northward is more similar to observation based estimates the extent of these anomalies can be rather large in both model versions as also seen in observations e g stretching from scotland to northern norway the easternmost branch into the nordic and barents seas carrying warm atlantic water is also improved by higher resolution both in terms of mean heat transport and variability in thermohaline properties a more detailed assessment of the link between the north atlantic ocean circulation and the thermohaline anomalies at the entrance of the nordic seas reveals that the high resolution is more consistent with mechanisms that are previously published this suggests better dynamics and variability in the subpolar region and the nordic seas in the high resolution compared to the medium resolution this is most likely due a better representation of the mean circulation in the studied region when using higher resolution as the poleward propagation of ocean heat anomalies is considered to be a key source of climate predictability we recommend that similar methodology presented herein should be performed on coupled climate models that are used for climate prediction

twentieth century tropical sea surface temperature trends revisited 1 this study compares the global distribution of 20th century sst and marine air temperature trends from a wide variety of data sets including un interpolated archives as well as globally complete reconstructions apart from the eastern equatorial pacific all datasets show consistency in their statistically significant trends with warming everywhere except the far northwestern atlantic the largest warming trends are found in the middle latitudes of both hemispheres two of the sst reconstructions exhibit statistically significant cooling trends over the eastern equatorial pacific in disagreement with the un interpolated sst and marine air temperature datasets which show statistically significant warming in this region twentieth century trends in tropical marine cloudiness precipitation and slp from independent data sets provide physically consistent evidence for a reduction in the strength of the atmospheric walker circulation accompanied by an eastward shift of deep convection from the western to the central equatorial pacific

searching for travertines calcretes and speleothems in deep time processes appearances predictions and the impact of plants common models for modern calcite precipitation in and around caves soils springs and streams involve co 2 supplied by thick high p co 2 biogenic soils which were probably thin or non existent before vascular plants indeed plant influenced chemical weathering might have caused accelerated terrestrial carbonate production from the devonian onwards however terrestrial carbonates have also been documented from the archaean proterozoic cambrian ordovician and silurian mechanisms which could have caused non marine carbonates to precipitate without organic rich soils are described and some geological events likely to have influenced non marine carbonate precipitation up to the origin of vascular plants are highlighted as organisms have evolved so have the petrographic characteristics of non marine carbonates some examples of this are also given here

a quantitative approach to soil occurrence in alluvial deposits and its application to the old red sandstone of britain palaeosols fossil soils are a major component of alluvial deposits in the geological record not only do these typically show considerable variations in their degrees of development within single formations but they also exhibit highly complex stratigraphic relationships with one another a simple quantitative approach to these variations is presented which provides a graphical means of assessing differences in soil palaeosol development within a sequence with calcic or petrocalcic horizons to illustrate the approach a range of palaeosols from the siluro devonian old red sandstone of britain are characterized in terms of the likely frequency and magnitude of depositional events which occurred during their formation in particular two alluvial suites from the manorbier area of south wales are analysed using this approach the technique should be widely applicable to other alluvial successions and provides a means of graphicallv presenting relationships between multiple palaeosols although the wide range of rates of formation of calcic and petrocalcic horizons precludes their use to provide narrow estimates of deposition rates

sediment recycling on siluro devonian floodplains some of the red mudstones in the red mark old red sandstone of llansteffan dyfed are interpreted as originating as sand sized mud aggregates pellets produced in soils and deposited from bed load in small sinuous channels by analogy with the channel country of australia such channels may represent periods of low discharge and reduced hydraulic efficiency when the floodplains were locally reworked in contrast larger channel fills with extraneous sediments may represent pluvial periods with increased discharge

physico chemical environment of pedogenic carbonate formation in devonian vertic palaeosols central appalachians usa the morphology and geochemistry of pedogenic carbonate found in vertic claystone palaeosols in the devonian catskill formation in central pennsylvania preserve a record of the physical and chemical environment of carbonate precipitation the carbonate is characterized by three distinct petrographic generations pedogenic rhizoliths and nodules are the earliest precipitated generation and typically consist of dull red brown luminescent micrite clear equant calcite spar cement fills voids in the centres of rhizoliths as well as circumgranular cracks and septarian voids in nodules early spar cements are nonluminescent to dull luminescent whereas later spar cements exhibit bright yellow orange luminescence late stage pedogenic fractures are always occluded with very bright yellow orange luminescent spar cements the incorporation of progressively higher concentrations of mn up to 34 000 ppm into successively younger calcite spar cements without concomitant increases in fe suggests carbonate precipitation from an evolving meteoric water in which mn2 became increasingly mobile over time the increased mobility is possibly due to decreasing eh resulting from oxidation of organic matter after rapid soil burial on the floodplain the amount of fe2 available for incorporation into calcite was limited because most iron was immobile having been earlier oxidized and bound to the palaeosol clay matrix as a poorly crystallized ferric oxide or oxyhydroxide mineral carbon isotope compositions of pedogenic carbonate correlate with the inferred depth of carbonate precipitation rhizoliths preserved below the lowest stratigraphic occurrences of pedogenic slickensides are consistently depleted in 3c relative to nodules which formed stratigraphically higher within the zone of active soil shrink and swell processes nodular carbonate precipitated in proximity to deep cracks in the soil is enriched due to increased gas exchange with isotopically heavy atmospheric c02 accordingly rhizolith compositions will most accurately estimate palaeoatmospheric levels of c02 the use of nodule compositions may result in overestimation of pco by as much as 30

a classification of rhizogenic root formed calcretes with examples from the upper jurassic lower cretaceous of spain and upper cretaceous of southern france reply abstract studies of fluvial sequences from the upper jurassic and lower cretaceous of the cameros basin spain and the upper cretaceous of the aquitaine basin france have revealed large numbers of calcrete profiles which have formed wholly or largely through the action of plant root calcification those from spain have formed by the calcification of root mats whereas those from france resulted from the accumulation of calcified root cells microcodium these root related rhizogenic calcretes developed in stages allowing developmental time series chronosequences to be identified contrasting with existing models for calcrete profile growth they provide unique examples where vegetation has been the dominant control on profile development and probably indicate specific vegetation types and palaeoecological settings the role of root activity in forming some quaternary calcretes is also discussed

late silurian and early devonian terrestrialisation ichnological insights from the lower old red sandstone of the anglo welsh basin u k abstract late silurian to early devonian deposits from the lower old red sandstone anglo welsh basin preserve a diverse assemblage of trace fossils that collectively comprise an important record of early terrestrialisation five main palaeoenvironmental categories are represented 1 perennial rivers 2 ephemeral rivers 3 floodplain lakes 4 alluvial fan and 5 marginal marine ichnocoenoses mainly reflect the activity of aquatic and or semi aquatic animals fluvial deposits preserve evidence for colonisation by eurypterids fish and myriapods ephemeral river channel margins splays preserve the most diverse ichnofauna composed of deposit feeders burrows and trackways produced by arthropods feeding and foraging in channel margin soft grounds that were colonised after fluvial flood events high densities of deposit feeding structures may indicate of explosive population growth in response to periodic acyclical replenishment of nutrients in these aquatic settings ichnotaxa common to both perennial and ephemeral fluvial environments suggest that there might have been only one aquatic ecosystem the degree to which the channel margin ichnofaunas record a truly subaerial terrestrial arthropod signature is difficult to ascertain and most trace makers were probably semi aquatic some terrestrial animals invaded channel margin areas to feed and were also capable of inhabiting high energy alluvial fan environments however the fans contain low diversity ichnological assemblages and were likely to have been inhabited by an opportunistic fauna possibly the only truly subaerial terrestrial ichnocoenosis is that of pedogenically modified mudrock with scoyenia which represents an early soil ichnofauna the majority of ichnocoenoses described from continental palaeoenvironments could be classified under the scoyenia ichnofacies marginal marine deposits contain an impoverished skolithos cruziana ichnofacies typical of silurian devonian brackish water assemblages

interdecadal variations in north atlantic sea surface temperature and associated atmospheric conditions abstract evidence is presented for a distinct pattern of ocean atmosphere relationship associated with interdecadal variability in the north atlantic region using a century of surface marine observations it is shown that middle and high latitude sea surface temperature sst display a long term fluctuation with negative anomalies before 1920 and during the 1970s and 1980s positive sst conditions prevailed from about 1930 to 1960 the pattern of interdecadal sst variability is constructed by subtracting the average field during 15 cold years from that during a similar interval of warm years the early century warming and the more recent cooling display a similar spatial pattern in both cases the pattern is basin scale and largely of one polarity with maxima in the vicinity of iceland in the labrador sea and northeast of bermuda the corresponding differences in surface atmospheric conditions are determined by averaging and subtracting in the same manner fields of sea level pressure slp and surf

enigmatic sedimentary structures in the lower old red sandstone south wales uk possible microbial influence on surface processes and early terrestrial food webs several enigmatic sedimentary structures are present in upper silurian and lower devonian terrestrial rocks of south wales these are millimetre ripples wrinkle structures cauliflower and molehill structures calcretized matgrounds pepper pots and fairy rings most of the structures occur on fine grained sandstone bedding surfaces in both inclined and non inclined red heterolithic deposits that form a large part of the lower old red sandstone in south wales these deposits consist of conspicuous units up to 3 m thick comprising millimetre to centimetre scale laminasets of alternating mudstone and fine grained sandstone interpreted as muddy point bars on ephemeral channel margins crevasse splay lobes or distal flood out deposits from ephemeral flow they are rich in trace fossils reflecting animal locomotion burrowing foraging ploughing and resting millimetre ripples and wrinkle structures are related to rapid growth of cyanobacterial mats on wet sediment surfaces especially in films of standing water that may have been a critical constituent of the food chain for terrestrial communities pustular cauliflower and molehill structures are preserved on tuffs and have been linked to algal blooms formed following an increase in nutrients due to ashfall into floodplain ponds the tuffs are associated with a diverse ichnofauna indicating that opportunist colonizers took advantage of an abundant food source

on the flow of atlantic water and temperature anomalies in the nordic seas toward the arctic ocean the climatic conditions over the arctic ocean are strongly influenced by the inflow of warm atlantic water conveyed by the norwegian atlantic slope current nwasc based on sea surface height ssh data from altimetry we develop a simple dynamical measure of the nwasc transport to diagnose its spatio temporal variability this supports a dynamical division of the nwasc into two flow regimes the svinoy branch svb in the southern norwegian sea and the fram strait branch fsb west of spitsbergen the svb transport is well correlated with the ssh and atmospheric variability within the nordic seas factors that also affect the inflow to the barents sea in contrast the fsb is influenced by regional atmospheric conditions around svalbard and northern barents sea using a composite analysis we further relate anomalous strong svb flow events to temperature fluctuations along the core of atlantic water a warm composite anomaly is found to propagate northward with a tendency to amplify enroute after these events a roughly 12 months delayed temperature signal is identified in the fsb however also in the lofoten basin interior a delayed temperature signal is found which appears to originate from the nwasc this study suggests that hydrographic anomalies both upstream from the north atlantic and locally generated in the norwegian sea are important for the oceanic heat and salt transport that eventually enters into the arctic

the anatomy of an early dinantian terraced floodplain palaeo environment and early diagenesis the lowermost carboniferous rocks in the cockburnspath area of east berwickshire southern scotland are interpreted as coastal floodplain sediments a lower mudstone dominated unit is composed of silty mudstones and shales with subordinate sandstones and argillaceous ferroan dolomites cementstones these are interpreted as distal floodplain sediments with periodic crevasse splay deposition the dark grey colour of the mudrocks suggests deposition in reducing conditions probably in floodplain lakes most of the cementstones are concretionary some with septarian cracks suggesting an early diagenetic origin an immature palaeosol suggests periodic pedogenesis under improved drainage a synsedimentary erosion surface indicates incision of a valley into the floodplain presumably in response to base level lowering an upper sandstone dominated unit starts with fine grained rippled sandstones cut by small channel sandstones these are interpreted as floodplain lake deposits fed by crevasse channels a distinctive conglomerate with cementstone clasts wood fragments and fish remains is interpreted as a major overbank deposit dumped into a pre existing floodplain lake a bivalve fauna was established in the overlying mudstones followed by a thin limestone with a restricted marine fossil assemblage showing that seawater flooding of the lakes occurred at times mudrocks throughout the sequence contain no pyrite except for the marine band which has an organic carbon sulphur ratio and degree of pyritization value typical of marine sediments the concretionary cementstones have d13c values around 4 to 6 0 00 pdb which are interpreted as indicative of anaerobic oxidation of organic matter the combined geochemical data suggest a significant involvement of iron reduction in cementstone formation although the d13c values are ambiguous in assessing the relative involvement of methanogenesis and methane oxidation limited seawater inundation of the floodplains might have supplied magnesium and calcium ions for dolomite formation assuming that any h2s derived as a result of sulphate reduction was oxidized by iron reduction alternatively a weathering source for solutes might have been involved

weathering plants and the long term carbon cycle the chemical weathering of ca mg silicate rocks is the principal process whereby co2 is removed from the atmosphere on long or multimillion year time scales at present vascular land plants exert an important influence on weathering by recycling water and by bringing about the secretion of acids and the buildup of high levels of co2 in soils before the spread of vascular plants on the continents during the mid paleozoic chemical weathering must have been achieved by higher levels of atmospheric co2 and or by the intercession of primitive land biota such as lichens and cyanobacteria from examination of several pre vascular weathering scenarios it is concluded that in order to prohibit unreasonably high levels of atmospheric co2 weathering during the precambrian and early paleozoic must have taken place under essentially closed system abiotic conditions linear feedback or via strong regulation by primitive biota preliminary examination of modern weathering by lichens over tens to thousands of years militates against the latter possibility however much more work needs to be done on the quantitative effect of both primitive biota and vascular plants on the rate of weathering and their response to changes in atmospheric co2 before anything more definitive can be said

the role of detrital composition and climate on the diagenetic evolution of continental molasses evidence from the cambro ordovician guaritas sequence southern brazil abstract the cambro ordovician molassic guaritas sequence camaqua basin southern brazil comprises alluvial fan and braided fluvial sandstones and conglomerates with intercalated aeolian and lacustrine deltaic deposits and andesitic lava flows the sediments display a complex detrital composition derived from plutonic gneissic acidic volcanic and low grade metamorphic source rocks this detrital assemblage was strongly modified by semi arid continental near surface diagenesis early cementation by hematite smectite quartz and calcite and the relatively limited burial prevented strong compaction and preserved some primary macroporosity in most of the sandstones whereas the absence of early cements and or abundance of ductile grains promoted substantial porosity destruction by compaction and the inhibition of further diagenetic modifications the diagenetic dissolution and replacement of volcanic rock fragments and detrital feldspars by clays and albite changed the original framework composition as well as the tectonic provenance classification of the sandstones detailed quantitative petrographic study allowed the reconstruction of the original detrital compositions and the distinction of six different pathways of diagenetic evolution of the sandstones attesting to the efficiency of this method for diagenetic modelling and provenance analyses of ancient sandstones

radio echo sounding and ice volume estimates of western nordenskiold land glaciers svalbard as part of ongoing work to obtain a reliable estimate of the total ice volume of svalbard glaciers and their potential contribution to sea level rise we present here volume calculations with detailed error estimates for ten glaciers on western nordenskiold land central spitsbergen svalbard the volume estimates are based upon a dense net of gpr retrieved ice thickness data collected over several field campaigns spanning the period 1999 2012 the total area and volume of the ensemble are 116 06 4 53 km 2 and 10 439 0 373 km 3 respectively while the individual areas volumes and average ice thickness lie within 2 6 50 4 km 2 0 08 5 54 km 3 and 29 108 m respectively volume area scaling relationships overestimate the total volume of these glaciers by up to 35 with respect to our calculation on the basis of the pattern of scattering in the radargrams we also analyse the hydrothermal structure of these glaciers nine of the ten are polythermal while only one is entirely cold

on the nature of decadal anomalies in north atlantic sea surface temperature north atlantic sea surface temperature data from the comprehensive ocean atmosphere data set were used to investigate the behavior of temperature anomalies on multiple year timescales during the period 1948 1992 monthly anomaly time series for each 2 square from the equator to 70 n were low pass filtered at 4 years and normalized by the local standard deviation attention is focused on the extreme events the upper and lower deciles of the anomaly time series a 45 year sequence of january maps shows the already familiar phenomena of generally cold conditions prior to 1951 a long warm interval from 1951 through 1967 and again a cold period from 1968 through 1977 the years 1978 through 1982 were largely devoid of persistent strong anomalies but moderate cold conditions returned during 1983 1986 warm conditions dominated the north atlantic from 1987 onward within these thermal epochs however a total of five cold anomaly features and nine warm anomaly features have been identified these features have individual lifetimes of 3 to 10 years a typical size is 20 of latitude or longitude but they range from barely detectable to spanning the width of the basin the latter especially in lower latitudes most of the anomalies move long distances along certain preferred paths these paths generally follow the routes of the subarctic and subtropical gyres anomalies originating off north america along the boundary between the gyres move northeastward toward the norwegian sea along the approximate route of the north atlantic current midlatitude anomalies originating at the eastern boundary tend to spread both northward and southward along the coast the speed of these movements 1 3 km d 1 is generally less than the expected speed of the near surface ocean circulation simple ideas about the effects of beta dynamics and air sea heat exchanges are briefly considered but do not provide a satisfactory explanation for the movements of the anomalies the long timescale of these extreme events and the continuity of their movements suggest a useful degree of predictability of sea surface temperature based on persistence and propagation of features

alluvial fan and wetland interactions evidence of seasonal slope wetlands from the silurian of south central wales uk distal environs of the ludlow age trichrug formation from south central wales uk detail deposition on the outer fringe of an ephemeral debris flow dominated alluvial fan debrites and subordinate sheetflood deposits are interbedded with sporadic thin sandstone dominated heterolithic units deposited in shallow ephemeral ponds in the axial valley the latter slope wetland system fringed the permeable alluvial fan deposits being maintained by streamflow precipitation and ground water recharge a prolonged high water table is indicated by low chroma intervals interpreted as the result of gleying a variety of redoximorphic indicators including colour mottling and ferricrete concretions are evidence of iron mobilization and concentration associated with a seasonally fluctuating water table the slope wetlands were colonized periodically by skolithos generating organisms most likely to have been arthropods the widespread occurrence of redoximorphic indicators and ferricrete contrasts markedly with calcrete vertisols in penecontemporaneous continental deposits lower old red sandstone of the region it is likely that the alluvial fan toe area was the site of a wetland depression which maintained a high though fluctuating water table in contrast the alluvial channel reaches of the surrounding drainage network were significantly better drained with floodplains prone to wetting and drying and vertisol palaeopedogenesis

carbon isotope record of late cambrian to early ordovician carbonates of the argentine precordillera a more than 2000 m thick cambrian ordovician carbonate platform succession developed on the exotic argentine precordillera terrane during rifting from laurentia and drifting towards gondwana on base of these carbonates a carbon isotope curve could be developed for the cambrian ordovician we measured 13ccarb and 13corg values on bulk rocks selected components and diagenetic cements whereas the carbon isotope signals of intertidal and supratidal rocks are altered by diagenesis most subtidal carbonates exhibit primary marine values we can report reliable curves for the middle late cambrian transition and for the latest cambrian to earliest middle ordovician the 13c curve matches well with the published data from global cambrian ordovician boundary sections excursions and shifts in the carbon isotope curve correspond to events in sequence stratigraphy this indicates the interdependence on sea level which rules the productivity and or preservation of organic carbon and therefore the partition between corg and ccarb burial

palaeosols as indicators of geomorphic stability in two old red sandstone alluvial suites south wales palaeosols fossil soils are abundant in the alluvial late silurian early devonian moor cliffs formation and rat island mudstone freshwater west formation of south dyfed south wales the palaeosols occur in thick mudstones deposited on floodplains under a seasonal semi arid climate and represent vertisol type soils simple single profiles are rare and most of the mudstone intervals exhibit complex overprinted profiles however a major difference exists between the palaeo vertisols in each of the two units studied the moor cliffs formation contains thick floodplain intervals with evidence of frequent erosion and reactivation of earlier soil horizons the associated coarser channel deposits mainly represent ephemeral streams the alluvial system was unstable flashy and prone to extensive stripping of stored floodplain sediment arroyos unstable ephemeral stream channels probably developed during this interval evidence for any marine influence on soil development is missing and previous speculations that the formation may represent deposition in an upper intertidal or supratidal system are not supported the rat island mudstone represents a complete contrast in that there was little or no stripping of floodplain sediments the channel deposits are typically of the fining upwards type representing more stable low sinuosity channels and with ephemeral stream floods by integrating the palaeosols a more detailed picture of the geomorphic history of these units can be formulated comparison with contemporary drainage basins indicates that a change in climate was a possible cause for the differences between the two units less frequent and more severe storms occurring during the deposition of the rat island mudstone

atmospheric pco2 and depositional environment from stable isotope geochemistry of calcrete nodules barremian lower cretaceous wealden beds england abstract nodular soil carbonates calcretes are present in overbank facies of lower cretaceous non marine wealden beds wessex formation of southern england field evidence suggests that these calcretes formed mostly under semi arid mediterranean type climatic conditions typical calcrete fabrics identified petrographically include floating detrital grains corroded grain margins and circumgranular cracks defining peds localized alteration of primary micrites is mainly associated with large cracks where early non ferroan diagenetic cementation and neomorphism was focused diagenetic ferroan calcites occur as void fills and yield relatively light carbon isotope and oxygen isotope compositions 13 c 15 0 18 o 6 3 compared to well preserved micrite 13 c 10 2 18 o 4 0 precise definition of 13 c values for well preserved micrites allow estimation of partial pressure of atmospheric co 2 p co 2 for the early barremian of 560 ppmv using a published diffusion reaction model the data suggest that atmospheric co 2 was low during the mid early cretaceous before rising to a previously defined mid cretaceous high data from calcretes in the weald clay highlight the need for selection of appropriate material and careful evaluation before p co 2 calculations are attempted the weald clay samples come from marshy palaeoenvironments where ingress of atmospheric co 2 into the soil zone was either reduced or prevented

on anomalous sea surface temperatures in the nordic seas abstract gridded sea surface temperature sst sea level pressure 10 m wind field and ice concentration data from the winters 1982 98 are used in a study of the large scale variability of the ssts in the nordic seas mean fields are extracted and areas of maximum variability identified a complex principal component analysis is applied to identify coherent structure of variability in the sst field the leading mode accounting for 39 of the variance reveals a band of high correlations at increasing phase lags along the west coast of norway across the greenland sea and south through the denmark strait the sst data contain two cycles of low frequency variability during the 17 winters studied having approximately 5 yr and 12 yr periods for the eastern parts of the nordic seas propagation speeds agree with other transport estimates this indicates that sst anomalies are representing upper ocean heat anomalies advected by the mean flow from north of scotland toward the barents sea this is not true

on model differences and skill in predicting sea surface temperature in the nordic and barents seas the nordic seas and the barents sea is the atlantic ocean s gateway to the arctic ocean and the gulf stream s northern extension brings large amounts of heat into this region and modulates climate in northwestern europe we have investigated the predictive skill of initialized hindcast simulations performed with three state of the art climate prediction models within the cmip5 framework focusing on sea surface temperature sst in the nordic seas and barents sea but also on sea ice extent and the subpolar north atlantic upstream the hindcasts are compared with observation based sst for the period 1961 2010 all models have significant predictive skill in specific regions at certain lead times however among the three models there is little consistency concerning which regions that display predictive skill and at what lead times for instance in the eastern nordic seas only one model has significant skill in predicting observed sst variability at longer lead times 7 10 years this region is of particular promise in terms of predictability as observed thermohaline anomalies progress from the subpolar north atlantic to the fram strait within the time frame of a couple of years in the same model predictive skill appears to move northward along a similar route as forecast time progresses we attribute this to the northward advection of sst anomalies contributing to skill at longer lead times in the eastern nordic seas the skill at these lead times in particular beats that of persistence forecast again indicating the potential role of ocean circulation as a source for skill furthermore we discuss possible explanations for the difference in skill among models such as different model resolutions initialization techniques and model climatologies and variance

concentration of carbon dioxide in the late cretaceous atmosphere stable carbon isotope data from late cretaceous maastrichtian palaeosols in india are used to estimate the concentration of carbon dioxide in the late cretaceous atmosphere we show that the maastrichtian atmosphere is unlikely to have contained more than about 1300 ppm by volume of co 2 this value agrees with an independently modeled value of co 2 in the late cretaceous atmosphere a low concentration of the greenhouse gas carbon dioxide in the maastrichtian atmosphere relative to concentrations in the earlier cretaceous is consistent with palaeotemperature information from terrestrial plant and marine fossils which suggest that the global climate cooled toward the end of the cretaceous period

sources and distribution of fresh water in the east greenland current abstract fresh water flowing from the arctic ocean via the east greenland current influences deep water formation in the nordic seas as well as the salinity of the surface and deep waters flowing from there this fresh water has three sources pacific water relatively fresh cf atlantic water river runoff and sea ice meltwater to determine the relative amounts of the three sources of fresh water in may 2002 we collected water samples across the east greenland current in sections from 81 5 n to the irminger sea south of denmark strait we used nitrate phosphate relationships to distinguish pacific waters from atlantic waters salinity to obtain the sum of sea ice melt water and river runoff water and total alkalinity to distinguish the latter river runoff contributed the largest part of the total fresh water component in some regions with some inventories exceeding 12 m pacific fresh water pacific source water s 32 cf atlantic source water s 34 9 typically provided about 1 3 of the river runoff contribution sea ice meltwater was very nearly non existent in the surface waters of all sections likely at least in part as a result of the samples being collected before the onset of the melt season the fresh water from the arctic ocean was strongly confined to near the greenland coast we thus conjecture that the main source of fresh water from the arctic ocean most strongly impacting deep convection in the nordic seas would be sea ice as opposed to fresh water in the liquid phase i e river runoff pacific fresh water and sea ice meltwater

subarctic and arctic sea surface temperature and its relation to ocean heat content 1982 2010 1 this is an examination of sst variability in the subarctic and arctic during the 29 year period 1982 2010 based primarily on data from the pathfinder avhrr data set as well as operational sst products from noaa and the uk meteorological office a goal is to explore the connection between sst variations in the subpolar gyres and sst variations further north with emphasis on the nordic seas because of their atmospheric exposure and connection to the overturning circulation after identifying and correcting for biases in pathfinder avhrr also present in the operational products the seasonal cycle and 29 year warming trend is described the analysis shows that much of the warming of the north atlantic subpolar gyre during the period occurred in 1990s and compensated for cooling during the decades of the early 1960s to mid 1990s in this same region superimposed on this warming trend the analysis reveals a succession of residual sst anomalies with 0 5 c amplitudes that seem to move out of the north atlantic subpolar gyre into the nordic seas following the north atlantic and norwegian currents within the nordic seas these sst anomalies slowly advect in a counterclockwise direction after approximately six years part of the anomalies exits the nordic seas through the east greenland current the connection between these sst anomalies and underlying anomalies of 0 300 m heat content is discussed the existence of these sst anomaliesand their origin at lower latitudes highlights the importance of ocean exchanges in influencing arctic climate

decadal predictability of the atlantic ocean in a coupled gcm forecast skill and optimal perturbations using linear inverse modeling abstract the decadal predictability of three dimensional atlantic ocean anomalies is examined in a coupled global climate model the third climate configuration of the met office unified model hadcm3 using a linear inverse modeling lim approach it is found that the evolution of temperature and salinity in the atlantic and the strength of the meridional overturning circulation moc can be effectively described by a linear dynamical system forced by white noise the forecasts produced using this linear model are more skillful than other reference forecasts for several decades furthermore significant nonnormal amplification is found under several different norms the regions from which this growth occurs are found to be fairly shallow and located in the far north atlantic initially anomalies in the nordic seas impact the moc and the anomalies then grow to fill the entire atlantic basin especially at depth over one to three decades it is found that the structure of the optimal initial conditio

first plants cooled the ordovician the late ordovician period ending 444 million years ago was marked by the onset of glaciations the expansion of non vascular land plants accelerated chemical weathering and may have drawn down enough atmospheric carbon dioxide to trigger the growth of ice sheets

carbon dioxide in the paleozoic atmosphere evidence from carbon isotope compositions of pedogenic carbonate stable carbon isotope compositions of pedogenic carbonate occurring in three clay rich vertic paleosols within paleozoic red bed successions in central pennsylvania provide a record of past pedogenic environments and can be used to estimate co sub 2 pressure p sub co sub 2 of the paleozoic atmosphere the delta sup 13 c values of carbonate nodules from paleosols in the deltaic lower bloomsburg formation upper silurian reflect the contribution of carbon from marine groundwater or fossils coupled with low biological activity the delta sup 13 c values of carbonate rhizocretions from stratigraphically high paleosols in the bloomsburg formation and in the alluvial catskill upper devonian and mauch chunk upper mississippian formations suggest an extensive c sub 3 flora and significant contribution of atmospheric co sub 2 paleozoic atmospheric co sub 2 levels inferred from delta sup 13 c of pedogenic carbonate are significantly higher than present levels

sources of strontium and calcium in desert soil and calcrete the carbon cycle significance of soil carbonate fluxes is subject to large uncertainties because it is not clear precisely how much calcium is derived from atmospheric sources compared with that from the chemical weathering of silicate minerals in the petrocalcic horizon calcrete of a pleistocene soil from the usda scs desert project area near las cruces nm approximately 1 5 g ca cm 3 has been added with an associated expansion of the profile of200 strontium isotope values for the labile cations and carbonate from the a b and k soil horizons have 87 sr 86 sr values that range from 0 7087 to 0 7093 similar to the values for easily soluble local dust and rain the parent material non calcareous camp rice alluvial sediment has a 87 sr 86 sr ratio of0 7165 mixing calculations indicate a minimum atmospheric contribution to soil carbonate calcium of 94 the more likely scenarios indicate at least 98 of the ca originated from atmospheric input the variations in 87 sr 86 sr ratios of soil silicate 0 7131 to 0 7173 are consistent with weathering of volcanogenic sediments and neoformation of clay minerals in the petrocalcic horizon moreover the sr isotope data suggest that 50 70 of silicate in the uppermost 25 cm of the profile could be atmosphere derived the isotopic composition of labile strontium in the a horizon and the mass distribution of silicon and calcium indicate that the uppermost portion of the profile is the present zone for the release of cations due to silicate weathering steady state models of the whole profile yield a sr weathering flux ranging from200 to 400 m gc m 2 ma 1 the results indicate that both the present day and long term contribution of calcium from silicate weathering is less than 2 of that supplied from the atmosphere and confirm that desert soil formation is not a significant sink for atmospheric carbon 1999 elsevier science b v all rights reserved

correlated signals and causal transport in ocean circulation this article presents a framework for interpreting the time lagged correlation of oceanographic data in terms of physical transport mechanisms previous studies have inferred aspects of ocean circulation by correlating fluctuations in temperature and salinity measurements at distant stations typically the time lag of greatest correlation is interpreted as an advective transit time and hence the advective speed of the current in this article we relate correlation functions directly to the underlying equations of fluid transport this is accomplished by expressing the correlation functions in terms of the green s function of the transport equation two types of correlation function are distinguished field forcing correlation and field field correlation their unique relationships to the green s function are illustrated in two idealized models of geophysical transport a leaky pipe model and an advective diffusive model both models show that the field forcing correlation function converges to the green s function as the characteristic time or length scale of forcing autocorrelation decreases the leaky pipe model provides an explanation for why advective speeds inferred from time lagged correlations are often less than the speed of the main current the advective diffusive model reveals a structural bias in the field field correlation function when used to estimate transit times

possible climate variability in the lower old red sandstone conigar pit sandstone member early devonian south wales uk abstract the early devonian conigar pit sandstone member cpsm of the freshwater west formation lower old red sandstone lochkovian age at freshwater west in south wales comprises a heterolithic predominantly alluvial suite mudstones fine to coarse grained sandstones conglomerates with varying depositional architecture a number of discrete facies associations are observed the fine grained inclined and non inclined heterolithic association is dominant within the cpsm it represents dryland sinuous channelized flow ihs bedsets and unconfined flow non inclined bedsets at terminal and intermediate floodouts deposited under semi arid conditions mudstones were deposited in two distinct environments associated with this semi arid river system laminated and burrowed reddish brown mudstones were deposited in shallow semi permanent lakes or pools on the floodplain massive mudstones were deposited as within channel muddy braid bars with sedimentary structures being lost during subsequent compaction the mudstones exhibit vertisol pedogenesis reflecting the seasonal wetting and drying associated with the semi arid climate periods of intense desiccation are indicated by deep desiccation cracks and associated rubbly surfaces possible though unproven tidal conditions influenced a small percentage of the heterolithic channels at freshwater west the extent of these channels is uncertain the coarser grained multi storey sandstone association was deposited by low sinuosity rivers with a fluctuating but perennial discharge associated with these laterally extensive sandbodies was a high water table with surface ponding wetlands that enabled the preservation of plant detritus during high discharge events flow expanded over the contemporaneous floodplain depositing the sheet sandstone association within splay complexes the interpretation that perennial discharge may have been triggered by basin wide climate change challenges the long held view that the lower ors climate was continuously semi arid in nature the spatial temporal extent of this climate change is uncertain as it is possible that the multi storey sandbodies were deposited by allogenic rivers draining a distant possibly uplifted source area a decrease in the observed frequency and maturity of vertisol profiles and a corresponding increase in multi storey sandbodies upward through the succession may reflect a long term episodic pattern of climate change

atmospheric pco2 perturbations associated with the central atlantic magmatic province the effects of a large igneous province on the concentration of atmospheric carbon dioxide pco2 are mostly unknown in this study we estimate pco2 from stable isotopic values of pedogenic carbonates interbedded with volcanics of the central atlantic magmatic province camp in the newark basin eastern north america we find pre camp pco2 values of 2000 parts per million ppm increasing to 4400 ppm immediately after the first volcanic unit followed by a steady decrease toward pre eruptive levels over the subsequent 300 thousand years a pattern that is repeated after the second and third flow units we interpret each pco2 increase as a direct response to magmatic activity primary outgassing or contact metamorphism the systematic decreases in pco2 after each magmatic episode probably reflect consumption of atmospheric co2 by weathering of silicates stimulated by fresh camp volcanics

does burial diagenesis reset pristine isotopic compositions in paleosol carbonates abstract sedimentological study of early oligocene continental carbonates from the fluvial dagshai formation of the himalayan foreland basin india resulted in the recognition of four different types namely soil palustrine pedogenically modified palustrine and groundwater carbonates stable oxygen and carbon isotopic 18 o and 13 c analyses of fabric selective carbonate microsamples show that although the pristine isotopic compositions are largely altered during deep burial diagenesis complete isotopic homogenization does not occur 18 o and 13 c analyses of 200 calcrete and palustrine carbonates from different stratigraphic horizons and comparison with 18 o of more robust bioapatite fossil vertebrate tooth phase show that dense micrites 70 carbonate invariably preserve the pristine 18 o value mean of 9 8 while altered carbonates show much lower 18 o value 13 8 such inhomogeneity causes large intra sample and intra soil profile variability as high as 5 suggesting that soils behave like a closed system where diagenetic overprinting occurs in local domains a simple fluid rock interaction model suggests active participation of clay minerals to enhance the effect of fluid rock ratio in local domains during diagenesis this places an upper limit of 70 micrite concentration above which the effect of diagenetic alteration is minimal careful sampling of dense micritic part of the soil carbonate nodules therefore does provide pristine isotopic composition and it is inappropriate as proposed recently to reject the paleoclimatic potential of all paleosol carbonates affected by burial diagenesis based on pristine 13 c value of 8 8 0 2 in soil carbonates an atmospheric co 2 concentration between 764 and 306 ppmv is estimated for the early oligocene 31 ma dagshai time these data show excellent agreement between two independent proxy records viz soil carbonate and marine alkenone and support early oligocene survival of the antarctic ice sheet

pedogenic carbonates as a proxy for palaeo co2 in the palaeozoic atmosphere abstract according to a model by cerling cerling t e 1991 carbon dioxide in the paleoatmosphere evidence from cenozoic and mesozoic paleosols am j sci 291 377 400 cerling t e 1999 stable carbon isotopes in palaeosol carbonates in thiry m simon coincon r eds palaeoweathering palaeosurfaces and related continental deposits vol 27 of spec publ int assoc sediment pp 43 60 the carbon isotope composition of calcretes should depend on the soil type and the co 2 concentration in the atmosphere we have tested cerling s model by investigating 14 palaeozoic sections with soil profiles a large number of carbonate types of different genetic origin exist in the localities examined comparing the palaeozoic samples with recent and subrecent calcretes it can be demonstrated that anhedral cryptocrystalline 2 concentration

spatial patterns of atmosphere ocean interaction in the northern winter abstract the variability of monthly mean sea surface temperature sst anomalies over the extratropical north atlantic and pacific and its relation to atmospheric circulation anomalies over the northern hemisphere during wintertime is investigated by applying eigenvector analysis to a 39 year dataset and correlating the time series of the resulting expansion coefficients with the hemispheric 500 mb height and sea level pressure fields in agreement with previous studies the simultaneous correlation between the tone series of the expansion coefficient of the first empirical orthogonal function eof 1 of north pacific sea surface temperature sst and the hemispheric 500 mb height field resembles the pacific north american pattern and the corresponding pattern for atlantic sst resembles the north atlantic oscillation in the vicinity of the conters of action of thew patterns the sst fluctuations associated with these modes explain on the order of half the variance of 500 mb height and slightly less of