on the wave number spectrum of oceanic mesoscale variability observed by the seasat altimeter variations of sea surface height measured by the seasat altimeter in nearly repeat orbits during the last 24 days of the mission are used to compute the wave number spectrum of mesoscale variability in various parts of the oceans the instrument noise level 150 cm2 cycles km has limited the resulting oceanic spectrum to wavelengths longer than 100 km we found that the characteristics of the oceanic spectrum are dependent on the energy level of the mesoscale variability in the high energy areas close to major current systems most of the energy is contained at wavelengths longer than 250 km at wavelengths shorter than 250 km the spectrum basically follows a k 5 k is wave number dependence in the low energy areas remote from major current systems the spectrum follows a k 1 dependence at wave lengths from 100 to 1000 km based on the assumption of horizontal isotropy of mesoscale variability scalar wave number spectra of sea surface height and geostrophic kinetic energy are also presented dynamical implications of these spectra are discussed the effects of residual geoid and atmospheric water vapor on the computed oceanic spectra have been rigorously examined it was found that the general characteristics of the oceanic spectra were not significantly affected by them

stable carbon isotope signatures preserved in authigenic gibbsite from a forested granitic regolith panola mt georgia usa six samples selected from a weathering profile developed on a granite in the panola mountain research watershed in the georgia piedmont were studied for their stable carbon isotopic properties the purpose was to understand the relationship between the stable carbon isotopic composition of the organic matter pool and the preservation of carbon in the authigenic soil minerals the method for yielding carbon from authigenic phases is based on that of yapp and

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

observations of the vertical structure of the eddy field in the kuroshio extension normalized kinetic energy frequency distributions at a site in the kuroshio extension along 152 e are independent of depth as a good first approximation the lowest frequencies are strongly vertically coherent from 350 to 6000 m depths nominal none of the other vertical sets of time series previously examined possess these characteristics to such a degree coherence being typically much lower between the thermocline and abyssal depths with spectral shape changing significantly as well the vertical distributions of eddy kinetic energy at this kuroshio extension site and for the gulf stream along 55 w are very similar if a depth independent contribution of approximately 100 cm2 s 2 be added to the former the latter observation suggests the existence of a more energetic weakly depth dependent component for the eddy field in the north atlantic than for the north pacific at special locations in the vicinity of their mid latitude jets possibly a signature of distinct instability mechanisms

coexisting goethite and gibbsite from a high paleolatitude 55 n late paleocene laterite concentration and 13c 12c ratios of occluded co2 and associated organic matter abstract a late paleocene 60 ma bp lateritic soil from northern ireland the antrim paleosol herein referred to as nire contains coexisting goethite gibbsite phyllosilicate and hematite the fe iii oxides exhibit pisolitic and liesegang type morphologies that are mutually exclusive in hand specimens x ray diffraction xrd measurements of al substituted for fe in goethite indicate two populations 1 low al liesegang type goethites 0 mol al and 2 high al pisolitic goethites 9 to 24 mol al selective dissolution and incremental vacuum dehydration decarbonation were used to determine the concentration and 13c values of co2 occluded in the respective structures of the goethites and gibbsites in this complex mixture of nire lateritic minerals the fe co3 oh component in the high al goethites appears to retain a proxy carbon isotopic record of vadose zone co2 in the ancient soil the 13c values of co2 occluded in coexisting goethites and gibbsites indicate that these minerals did not form in equilibrium with the same environmental co2 the measured mole fractions x of fe co3 oh in the high al goethites range from 0 0059 0 0005 to 0 0077 0 0006 and correspond to soil co2 concentrations of 28 000 to 37 000 ppmv the average values of x and 13c for the four high al goethites are 0 0067 0 0007 and 20 1 0 5 respectively the 13c value of the organic matter undergoing oxidation in this midlatitude 55 n late paleocene soil appears to have been 28 2 taken together these data indicate an atmospheric co2 concentration of 2400 ppmv 1200 ppmv at 60 ma bp the inferred high concentration of atmospheric co2 would have been coincident with the warm global climate of the late paleocene and is consistent with the idea that co2 plays an important role in climate variation

glaciation aridification and carbon sequestration in the permo carboniferous the isotopic record from low latitudes to evaluate the isotopic record of climate change and carbon sequestration in the late paleozoic we have compiled new and published oxygen and carbon isotopic measurements of more than 2000 brachiopod shells from carboniferous through middle permian 359 260 ma strata we focus on the isotopic records from the u s midcontinent and the russian platform because these two regions provide well preserved marine fossils spanning a broad time interval both regions show a 18o increase at the mid carboniferous boundary ca 318 ma that roughly correlates with geologic evidence for an expansion of gondwanan glaciers only the russian platform record shows a 18o maximum during the glacial maximum in the asselian in contrast to a previous study korte c jasper t kozur h w and veizer j 2005 18o and 13c of permian brachiopods a record of seawater evolution and continental glaciation palaeogeogr palaeoclimatol palaeoecol 224 333 351 our data show no oxygen isotope evidence for glacial retreat in the early permian but instead show increasing 18o values related to aridification dissimilarity in the 18o trends for the epicontinental seas of north american and the russian platform suggests that at least one region experienced periodic restriction that altered regional salinities and seawater 18o values these results highlight the need for complementary proxies to identify restricted circulation in epicontinental seas carbon isotopic compositions of carbonates exhibit substantial regional variation with low values in western north america intermediate values in the midcontinent and high values in the sverdrup basin russian platform and northern spain nevertheless both u s midcontinent and russian platform records show a late serpukhovian minimum a sharp increase across the mid carboniferous boundary and a minimum centered on the kasimovian the correlative increase in brachiopod 13c and 18o values at the mid carboniferous boundary is our best isotopic evidence for a link between the carbon burial and glaciation in the permo carboniferous

the late carboniferous glacial to postglacial transition facies and sequence stratigraphy western paganzo basin argentina abstract namurian early westphalian glacial postglacial deposits have been documented in the paganzo basin argentina but integrated sequence stratigraphic and sedimentological analyses of the glacial postglacial transition are rare in the cuesta de huaco section the glacial postglacial transition encompasses the lower sequence of the existing schemes glacioeustatic changes in sea level controlled the architecture and vertical arrangement of facies the basal sequence boundary is coeval with the onset of glaciation when sea level fell contemporaneous with glacial erosion and bypass of sediment the upper sequence boundary is a high frequency sequence boundary the basal deposits are interpreted as an early transgressive systems tract etst initiated during glacial retreat the interval fines upward contains current reworked diamictites conglomerates and sandstones deposited in a subglacial to proglacial environment facies i ii and ice rafted glaciomarine rhythmites facies iii postglacial brackish marine black shales facies iv represent the late transgressive systems tract ltst micritic limestone beds were deposited during a period of sediment starvation coeval with the maximum marine inundation in the basin mfz it marks a turnaround in the stacking pattern that became coarsening and thickening upward during the overlying highstand systems tract hst it consists of fine grained turbidites facies v and classical turbidites with wave reworked beds at the top facies vi deposited in a shallow deltaic systems intervening postglacial brackish deposits contain an ichnofauna dominated by trackways of arthropods and minor grazing traces preserved in bedding planes that resemble nonmarine ichnocoenoses and differ from the archetypal brackish ichnofaunas even when palynological data support the saline depleted environment

stable carbon isotope budget of co2 in a wet modern soil as inferred from fe co3 oh in pedogenic goethite possible role of calcite dissolution abstract 13c values of the fe co3 oh component in pedogenic goethites from a young soil developed on the eocene weches formation in east texas increase from approximately 13 or 14 at depths of 31 64 cm to values around 6 to 4 at depths greater than 122 cm this spatial distribution of 13c values suggests that dissolution of precursor fossiliferous marine calcite still present at deeper levels in the soil has contributed significantly to the isotopic budget of co2 in this soil a local isotopic material balance was calculated for the soil co2 at each sample depth using a calcite 13c value of 1 an organic matter 13c value of 25 and the measured 13c value of the fe co3 oh component in each sample although there is presently no calcite in the upper 120 cm of the profile the calculated apparent contribution of co2 from a calcite source ranges from 16 to 45 at these shallow depths below 120 cm dissolution of calcite appears to contribute more than 50 of the co2 in the soil gas similar results might be expected in other wet goethite bearing soils that contain relict calcite and thus have not achieved the highly leached characteristics of laterites such as those in the amazon basin models of the soil co2 budget in such systems may need to consider both oxidation of organic matter and dissolution of carbonate minerals as in situ sources of carbon isotope variation in co2 the variation with depth of the 13c values of the fe co3 oh component suggests an ongoing process of goethite dissolution and reprecipitation in the active aerobic soil zone if so the extremely low solubility of goethite in oxidizing environments suggests that this dissolution process is probably biologically mediated dissolution and reprecipitation of goethite in an aerobic soil would favor the recording of steady state soil co2 13c patterns preservation of such information in ancient soils would probably depend upon burial and consequent removal from the biologically active soil zone

carbon isotopes in continental weathering environments and variations in ancient atmospheric co2 pressure abstract abundance and carbon isotope data from an fe co3 oh component in apparent solid solution in oolitic goethites have been used to infer ancient atmospheric co2 pressures a test of the validity of these estimates might be comparisons of the carbon isotope compositions of fe co3 oh in oolitic goethites with time equivalent pedogenic calcites temporal trends of the oolitic goethite and pedogenic calcite 13c values are generally similar but time equivalent samples from each of these two groups are not common in the existing data to facilitate discussion of the concept comparisons were made of available goethite and calcite samples even though ages of the compared samples in each pair were not identical in four out of the five comparisons fe co3 oh abundance and 13c data were combined with pedogenic calcite 13c data to calculate physically reasonable soil co2 concentrations for the ancient calcitic soids this suggests that the compared oolitic goethite and pedogenic calcite systems were responding to the same global scale phenomenon i e atmospheric co2 atmospheric pco2 as determined from the goethites in these four well behaved cases ranged from values indistinguishable from modern within analytical uncertainty to values up to approximately 16 time modern modern atmospheric pco2 was taken to be 10 3 5 atm one interpretation of the fifth anomalous comparison is that atmospheric co2 levels increased from about 3 times modern to about 18 times modern from the triassic into the early jurassic this inferred value for the pco2 of the early jurassic atmosphere is not uniquely constrained by the existing data and needs to be substantiated however even considerably lower early jurassic atmospheric pco2 values of 6 to 9 times modern i e 1 3 to 1 2 of the estimated value of 18 times modern would still indicate significant differences between the global carbon cycles then and now these results highlight the need for more research on the behavior of the atmosphere during and after the triassic jurassic transition

the capillary fringe and its effect on water table response abstract shallow water tables are often observed to respond in a highly disproportionate manner to precipitation events that is the magnitude of the response is often much greater than would be predicted on the basis of the specific yield of the geologic material and the amount of rainfall physical arguments are presented to show that if the capillary fringe the zone of tension saturation extends to ground surface then the addition of a very small amount of water can result in an immediate and large rise in the water table the arguments are supported by a field experiment in which the addition of 0 3 cm of water caused the water table to rise 30 cm in 0 25 min thus demonstrating the large and highly transient influence of the capillary fringe on the position of the water table the evidence in this study as well as recent work of others suggests that the capillary fringe effect could have a major influence on the process of stream flow generation contaminant transport to surface waters and contaminant transport in hydrogeologic regimes having shallow water tables it is further shown that calculations of groundwater recharge and consumptive use based on water table response and an assumed specific yield could be substantially in error

paleoenvironmental implications of concentration and 13c 12c ratios of fe co3 oh in goethite from a mid latitude cenomanian laterite in southwestern minnesota abstract a mid cretaceous 95 ma laterite in southwestern minnesota contains pisolites that consist primarily of gibbsite quartz and kaolinite with smaller amounts of goethite feooh and hematite the presence of minor berthierine an fe ii sheet silicate suggests that this cenomanian laterite experienced some degree of low temperature reductive diagenesis during its burial history the prospects for extracting useful paleoenvironmental information from the pisolitic goethite were explored by studying measured mole fraction x m and 13 c m values of the fe co 3 oh component in solid solution in the goethite using the method of incremental vacuum dehydration decarbonation data arrays that occupy distinctly different domains in plots of 13 c m vs 1 x m suggest the existence of two generations of goethite in the pisolites the apparently younger generation of goethite generation 2 evolves co 2 at 170 c while the older generation generation 1 evolves co 2 at 220 c the distribution of the data suggests that generation 2 goethite is a proxy for mixing of co 2 from three distinct co 2 sources in an oxidative environment which post dated the reductive diagenesis the small amount of generation 1 goethite seems to have persisted through the reductive diagenesis and nine of the generation 1 goethite data appear to define a proxy two endmember soil co 2 mixing line such two component mixing is consistent with expectations for a highly evolved carbonate free laterite i e the pre diagenetic cenomanian weathering system the 13 c m values of these nine data points range from 23 1 to 13 7 whereas x m values range from 0 0007 to 0 0222 linear regression of these nine data yields a slope of 0 0064 which corresponds to an ancient tropospheric co 2 concentration of about 1900 ppmv isotopic data from pisolitic kaolinite indicate a paleotemperature of about 24 c at a paleolatitude of 40 n this is substantially warmer than modern continental temperatures at such latitudes and is consistent with published indications of a generally warmer mid cretaceous climate moreover the correspondence of a warmer mid cretaceous climate with the inferred relatively high concentration of cenomanian tropospheric co 2 1900 ppmv is consistent with the idea that variations of atmospheric co 2 have a relation to climate change the results of this study emphasize the importance of careful evaluation of incremental dehydration decarbonation data from natural goethites to assess the possibility that more than one generation of goethite is present in a sample however the results also indicate that the carbon isotope information recorded in admixed goethite generations may be sorted out and used in paleoenvironmental interpretations

the carbon isotope geochemistry of goethite α feooh in ironstone of the upper ordovician neda formation wisconsin usa implications for early paleozoic continental environments carbon isotope exchange experiments and data from natural samples in a state of isotopic disequilibrium indicate that the apparent fe co3 oh component in natural goethites is a closed system these results support the solid solution model for fe co3 oh in goethite the carbon isotope geochemistry of the oolitic neda formation ironstone at occurrences in wisconsin and iowa is consistent with goethite formation in a late ordovician subaerial weathering environment 13c values of the fe co3 oh component in neda formation goethite indicate that organic matter was being oxidized to produce co2 in the ancient weathering profile the 13c value of this organic matter was about 27 at depths greater than about 20 cm the partial pressure of co2 in the late ordovician weathering profile was 5 6 times larger than the pco2 of the earth s atmosphere at that time this high soil co2 partial pressure and its origin in the oxidation of organic matter suggest that there was substantial biological activity on continental land surfaces prior to the widespread colonization by vascular plants it indicates a possible role for biological activity in the chemical weathering of continents in the early paleozoic

influence of changing hydrology on pedogenic calcite precipitation in vertisols dance bayou brazoria county texas u s a implications for estimating paleoatmospheric pco2 the 13 c values of pedogenic soil formed calcite preserved in the sedimentary record have been used to estimate atmospheric pco 2 using the paleosol calcite paleobarometer a fundamental assumption for applying this paleobarometer is that atmospheric co 2 concentrations have a direct influence on the measured pedogenic calcite 13 c values as a result of open system exchange between atmospheric and soil respired co 2 here we address the timing of calcite precipitation in relation to the soil saturation state and soil atmosphere connectivity in a modern vertisol smectitic clay rich soil seasonally saturated in brazoria county texas u s a luminescent phases of calcite growth under cathodoluminescence microscopy have more negative 13 c values 13 c 11 1 vpdb 0 78 1 than the non luminescent phases 13 c 2 53 vpdb 1 41 1 the luminescent phase of calcite formed during the water saturated portion of the year thereby minimizing the incorporation of atmospheric co 2 and negating its use for pco 2 estimations the non luminescent phase formed during the well drained portion of the year when atmospheric co 2 mixed with soil respired co 2 and is therefore useful for pco 2 estimation from these results we present a model to independently test the saturation state of a paleosol at the time of pedogenic carbonate precipitation finally we calculate soil respired co 2 concentrations that are an order of magnitude lower than those that are typically assumed in the soil carbonate paleobarometer equation

stationary and traveling mesoscale perturbations in the kuroshio extension current abstract several hundred xbt observations in the western north pacific were collected each month over a 2 year period 1976 78 they have been assembled into a monthly map sequence of thermocline temperature in the kuroshio extension current having 100 km spatial resolution the overall time men of the maps exhibits mesoscale 200 600 km perturbations which correlate with several major bathymetric features especially the shatsky rise time variability about the mean decreases significantly cast of the shatsky rise in addition time variable mesoscale disturbances propagate zonally westward at 3 8 cm s 1 attempts to explain the observed propagation phase velocity through simple analytic baroclinic rossby wave theory lead to the implication that there exists in the region an eastward deep mean flow of 3 or 4 cm s 1 direct current measurements of long duration are required to help resolve and explain these observations

meanders of the gulf stream downstream from cape hatteras 1975 1978 abstract weekly gulf stream paths within 1000 km downstream of cape hatteras were obtained for 1975 78 from the navy s weekly eofa charts based on satellite ir imagery they displayed two dominant meander modes first a standing meander energetic over periods between 4 months and at least 4 years and second down stream propagating meanders that were most energetic at periods of several weeks the long period standing meander was confined between nodes located at the separation point near cape hatteras i e where the stream s mean path turns seaward and at a point about 600 km farther downstream the rms amplitude was 36 km at the antinode the amplitude of propagating meanders increased rapidly in the first 200 km downstream of the separation point where the capture of warm core eddies was common farther down stream the predominant meanders had a wavelength averaging 330 km a period averaging 1 5 month a phase speed averaging 8 cm s 1 a downstream group speed averaging 17 cm s 1 and downstrea

estimating long term soil respiration rates from carbon isotopes occluded in gibbsite abstract carbon occluded in the soil gibbsite crystal structure at the panola mountain research watershed georgia u s is presumed to be in isotopic equilibrium with the co2 respired from soil organics by microbes and plant roots fitting of the stable carbon isotopic data to a fickian diffusion based depth function results in an estimate of 47 gc m 2 y 1 for the long term soil respiration rate a numerical model that includes depth dependent production and diffusion terms results in estimates of 28 12 gc m 2 y 1 these values range from 15 to 50 times less than the average of modern values for mixed deciduous forests in wet temperate climates this disparity has several implications for our understanding of the geologic record of climate change which include 1 evidence for a cooler and seasonally drier climate during the mid holocene in the southeastern u s or 2 fluxes of carbon from the soil pool as recorded by soil mineral proxies i e long term soil respiration rates under estimate atmosphere annual carbon flux measurements i e short term measures and 3 the need to refine soil respiration models used to relate paleosol stable carbon isotopic measurements to paleo atmospheric p co 2 estimates

estimates of the geostrophic stream function in the western north pacific from xbt surveys the upper ocean temperature and dynamic height fields are correlated in the western north pacific ocean this relationship can be used to map a relative geostrophic stream function of the kuroshio extension using temperature data from expendable bathythermograph xbt surveys we have examined the ability of the north pacific ship of opportunity xbt program known as transpac to carry out this procedure estimates of 600 1200 dbar geostrophic shear were generated from the xbt data utilizing objective mapping techniques these estimates were compared with measured currents at 600 m relative to 1200 m along 152 e from 27 n to 42 n the estimated and measured relative currents are positively correlated with an rms error of 6 cm s over a measured dynamic range of 30 cm s however the xbt estimated shears consistently underestimate the measured values by a factor of 2 to 3 the underestimate of the amplitude is the result of both undersampling and mapping produres that eliminate high wavenumber contributions of the dynamic height variability these factors appear to be responsible for previous differences in amplitude between directly measured and transpac xbt estimated values of relative eddy kinetic energy and reynolds stress the transpac xbt survey can only monitor qualitatively the dynamic topography of the kuroshio extension meanders and rings the variability outside of the extension with a temperature range of 3 c cannot be resolved because of inaccuracies in the temperature dynamic height relationship to monitor the kuroshio extension variability in the future it is recommended that transpac xbt resources in the western north pacific concentrate on obtaining a denser sample of the field during the fall and winter seasons because of incomplete ship track coverage in spring and summer

decline of soil respiration in northeastern tibet through the transition into the oligocene icehouse abstract soil respiration rs the production of carbon dioxide in soils increases dramatically from deserts to forested ecosystems rs values thus provide a potential tool to identify past ecosystems if recorded in sedimentary archives here we propose a quantitative method to reconstruct past rs values from paleosols this method reverses the soil paleobarometer a proxy that estimates past atmospheric co2 concentration values co2atm from paleosols while considering a narrow range of variation for rs we use past co2atm values from marine proxies to reconstruct soil respiration from a 20 million year long isotopic record from northeastern tibet covering the transition from the eocene greenhouse to the oligocene icehouse we show that rs dropped at least 4 fold through the transition into the oligocene icehouse marking the spread of boreal desert steppes of central asia we show that increasing aridity and the decline of monsoonal rainfall in parallel with global cooling caused the fall of soil respiration these highly dynamic rs emphasize the need for a systematic screening of paleosol isotopic data before using the soil paleobarometer to reconstruct co2atm

climate controls on soil respired co2 in the united states implications for 21st century chemical weathering rates in temperate and arid ecosystems abstract the most recent ipcc 2007 report predicts that regional scale precipitation patterns will change significantly in the 21st century as a result of increasing atmospheric co 2 the amount of respired co 2 stored in the soil atmosphere is heavily influenced by climate and the concentration of co 2 in soils controls the concentration of dissolved co 2 co 2aq in pore water involved in chemical weathering therefore we can expect changes to chemical weathering rates as a result of climate change which can influence the global carbon cycle through the consumption of co 2 during continental silicate weathering these changes may even be important on human timescales to predict changes to the co 2aq of soil water we have produced an extensive literature review of soil respired co 2 measurements to study the spatial variability of soil respired co 2 we show that respired co 2 concentrations and co 2aq vary with precipitation this study focuses on the western united states where we find a strong relationship between summer average soil respired co 2 and mean annual precipitation for soils forming in or below 900 mm yr 1 precipitation r 2 0 91 the correlation breaks down when higher mean annual precipitation rates are considered restricting the use of this relationship to arid to subhumid precipitation regimes we estimate the response of co 2aq in soil pore water in the western united states to projected anthropogenic co 2 emissions using this new relationship and projected changes in precipitation simulated by the north american regional climate change assessment program for the decade 2051 2060 according to our model co 2aq in soil pore water is expected to decrease by up to 50 in the southwestern united states and to increase by up to 50 in areas of the northern and central great plains these results have important implications for co 2 consumption and changes to terrestrial carbon cycling in the next century

orbital and co2 forcing of late paleozoic continental ice sheets 1 contrasting views of the size duration and history of the gondwanan continental ice sheets have been proposed from late paleozoic glaciological and sedimentological evidence to evaluate these differing views a coupled ice sheet climate model is used to simulate continental ice sheets under a wide range of late paleozoic orbital and pco2 conditions the model experiments indicate that orbital variations at pco2 concentrations below 2x pre industrial atmospheric levels pal 280 ppm produce large changes in late paleozoic ice volume 1 3 108 km3 and sea level 20 to 245 m between 2 and 8x pal gondwana continental ice is simulated only under the most extreme southern hemisphere cold summer orbit but still produces significant ice volumes 8 12 107 km3 our results highlight the important role of atmospheric co2 in determining the distribution volume and stability of late paleozoic ice sheets factors that ultimately impacted sea level cyclothem deposition and global climate and reconcile disparate views of the late paleozoic ice age

a comparison of the mid latitude eddy fields in the western north atlantic and north pacific oceans abstract latitudinal distributions of estimates of eddy kinetic energy and off diagonal component of the horizontal reynolds stresses are demonstrated to have similar shapes at corresponding generally western locations but at much different depths in the mid latitude north atlantic and north pacific oceans this comparison is based on direct current measurements at abyssal depths in the north atlantic along 55 w and on indirect estimates of upper level velocity differences in the vertical for the north pacific between the izu or izu ogasawara or south honshu ridge and the shatsky rise these sections span the more energetic segments of the kuroshio extension and gulf stream systems

a pedogenic goethite record of soil co2 variations as a response to soil moisture content abstract the terrestrial carbon cycle and the role of atmospheric co 2 concentrations in controlling global temperatures can be inferred from the study of ancient soils paleosols soil formed goethite and calcite have been the primary minerals used as a geochemical proxy for reconstructing atmospheric p co 2 from ancient terrestrial records in the case of goethite optimum sampling strategies for reconstructing p co 2 focus on the portion of the soil profile that displays steep gradients in both soil co 2 concentration and 13 c values of soil co 2 such that a keeling plot can be developed for a given soil and atmospheric p co 2 can be calculated from it we report data from a carboniferous paleosol that depart from the expected linear trends the results indicate that pedogenic goethite is sensitive to variations in the isotopic composition of soil co 2 over a range of timescales and can record these variations in the carbon isotope composition and mole fraction of fe co 3 oh in solid solution with goethite we explore possible environmental conditions that can drive these changes as a function of either moisture controlled variations in soil respired co 2 or in the residence time of carbon in soils the implications of this result are overestimation of paleoatmospheric p co 2 from pedogenic goethite

classification of paleosols despite increased interest in paleosols during the past decade no satisfactory classification is in current use presented here is a largely descriptive classification system that utilizes those pedogenic features that have the highest preservation potential in the rock record emphasized in the classification are morphological and mineralogical features that are easily recognizable in the field and through the petrographic microscope the classification is based on evaluation of the relative prominence in a paleosol of six pedogenic features or processes organic matter content horizonation redox conditions in situ mineral alteration illuviation of insoluble minerals compounds and accumulation of soluble minerals the most prominent of these six features processes provides the key to classifying a paleosol into one of nine orders four of the order names are borrowed from soil taxonomy histosol spodosol oxisol vertisol whereas the other five order names are presented here for the first time calcisol gypsisol gleysol argillisol protosol the orders may be preceded by one or more subordinate modifiers that describe other important features of the paleosol the classification is relatively easy to apply to the rock record and should enhance communication and aid in the standardization of terminology

recent long term moored instrument observations in the western north pacific selected results based on the first deployment duration was 298 324 days depending on specific location of an array of 38 current temperature meters on 10 moorings along 152 e from 28 n to 41 n are discussed abyssal eddy kinetic energies along 152 e near the kuroshio extension are a factor of 2 to possibly 5 lower than those previously observed at similar depths close to the energetic regions of the gulf stream the thermocline kinetic energy frequency distribution at 28 n 152 e is similar in shape to that observed at a site near 31 n 70 w but not 28 n 70 w although the total energy levels are quite different however the distance from the corresponding strong current regimes is nearly the same the largest scale latitudinal distribution of the off diagonal component of horizontal reynolds stress has a characteristic general shape that is negative to the south and positive to the north of the gulf stream or kuroshio extension or mid latitude jet at all depths for all longitudes where such data are available in both oceans and in the numerical experiments examined

apparent gibbsite growth ages for regolith in the georgia piedmont abstract carbon bound in gibbsite collected from a residual weathering profile developed on a paleozoic granite in the georgia piedmont was examined for its 14 c content and found to be geologically young the study site located at the panola mountain research watershed has developed a granite saprolite soil regolith in which 14 c gibbsite model ages deep within the profile c horizon average about 8000 years near the surface a and b horizon 14 c gibbsite model ages range from 2100 to 4200 years quartz has acquired 26 al and 10 be inventories suggesting a near surface residence time of at least 90 000 years this age disparity supports the notion that secondary minerals undergo significant recrystallization as weathering fronts propagate into the landscape combining the results of 14 c 26 al and 10 be analyses offers the potential to assess differential rates of chemical weathering and continental denudation to understand better the links between rates of silicate rock weathering climate and soil residence times

co2 forced climate and vegetation instability during late paleozoic deglaciation the late paleozoic deglaciation is the vegetated earth9s only recorded icehouse to greenhouse transition yet the climate dynamics remain enigmatic by using the stable isotopic compositions of soil formed minerals fossil plant matter and shallow water brachiopods we estimated atmospheric partial pressure of carbon dioxide pco2 and tropical marine surface temperatures during this climate transition comparison to southern gondwanan glacial records documents covariance between inferred shifts in pco2 temperature and ice volume consistent with greenhouse gas forcing of climate major restructuring of paleotropical flora in western euramerica occurred in step with climate and pco2 shifts illustrating the biotic impact associated with past co2 forced turnover to a permanent ice free world

modern soil system constraints on reconstructing deep time atmospheric co2 abstract paleosol carbonate based estimates of paleo atmospheric co 2 play a prominent role in constraining radiative forcing and climate sensitivity in the deep time large uncertainty in paleo co 2 estimates made using the paleosol carbonate co 2 barometer however arises primarily from their sensitivity to soil respired co 2 s z this parameter is poorly constrained due to a paucity of soil co 2 measurements during carbonate formation in modern soils and a lack of widely applicable proxies of paleo soil co 2 here the 13 c values of carbonate and soil organic matter som pairs from 130 holocene soils are applied to a two component co 2 mixing equation to define soil order specific ranges of soil co 2 applicable for constraining s z in their corresponding paleosol analogs equilibrium carbonate som pairs characterized by 13 c carb som values of 12 2 15 8 define a mean effective fractionation of 14 1 and overall inferred total soil co 2 contents during calcite formation of s z during calcite formation is 1500 2000 ppmv range of 500 2500 ppmv overall higher values 2000 5000 ppmv are indicated by the subset of these soils characterized by higher moisture content and productivity near atmospheric levels 400 200 ppmv of estimated s z are indicated by immature soils recording their low soil productivity vertisols define the largest range in total soil co 2 25 000 ppmv reflecting their seasonally driven dynamic hydrochemistry a s z range of 1000 10 000 ppmv is suggested for paleo vertisols for which calcite precipitation can be constrained to have occurred in an open system with two component co 2 mixing with a best estimate of 2000 ppmv 1000 ppmv appropriate for paleo vertisols for which evidence of protracted water saturation is lacking mollisol pairs define a best estimate of s z of 2500 ppmv range of 600 4000 ppmv for late cretaceous and cenozoic analogs non equilibrium pairs with 13 c values 16 make up 51 of the dataset lending support to the hypothesis that pedogenic carbonate precipitation occurs during periods of low productivity in a soil atmosphere with a large component of atmospheric co 2 predictable scaling between estimated soil co 2 and the difference in 13 c between measured pedogenic carbonate and that predicted to have formed from soil respired co 2 inferred from measured som can be used to further constrain appropriate ranges of s z for reconstruction of paleo atmospheric p co 2 soil co 2 estimates are poorly correlated to mean annual precipitation likely reflecting that for carbonate bearing soils where moisture limits co 2 production total soil co 2 is most strongly influenced by actual evapotranspiration

body wave magnitude variation at yucca flat nevada abstract teleseismic body wave magnitudes due to nuclear tests at yucca flat nevada display a fluctuation of approximately 0 2 m b units the magnitude anomaly correlates well with geologic structure at this test site and it is hypothesized that a seismic response model of the local structure could account for most of the variance in the magnitude observations a detailed model of the geophysical structure along a profile near the center of yucca flat has been constructed from independent geologic and geophysical data the seismic response of this model has been calculated for a global network of six observing stations the theoretical m b anomaly compares favorably with the observed anomaly corrections to the observed magnitudes based on the model would result in an order of magnitude decrease in the variance of the observations

goethite calcite and organic matter from permian and triassic soils carbon isotopes and co2 concentrations abstract pedogenic goethites in each of two early permian paleosols appear to record mixing of two isotopically distinct co2 components atmospheric co2 and co2 from in situ oxidation of organic matter the 13c values measured for the fe co3 oh component in solid solution in these permian goethites are 13 5 for the lower leonardian 283 ma bp paleosol mcgoeth and 13 9 for the upper leonardian 270 ma bp paleosol sap these goethites contain the most 13c rich fe co3 oh measured to date for pedogenic goethites crystallized in soils exhibiting mixing of the two aforementioned co2 components 13c measured for 43 organic matter samples in the lower leonardian waggoner ranch fm has an average value of 20 3 1 1 1s the average value yields a calculated early permian atmospheric p co 2 value of about 1 pal but the scatter in the measured 13c values of organic matter permits a calculated maximum p co 2 of 11 pal pal present atmospheric level measured values of the mole fraction of fe co3 oh in mcgoeth and sap correspond to soil co2 concentrations in the early permian paleosol profiles of 54 000 and 50 000 ppmv respectively such high soil co2 concentrations are similar to modern soils in warm wet environments the average 13c values of pedogenic calcite from 9 paleosol profiles stratigraphically associated with mcgoeth waggoner ranch fm range from 6 5 to 4 4 with a mean 13c value for all profiles of 5 4 thus the value of 13c between the pedogenic calcite data set and mcgoeth is 8 1 0 9 which is in reasonable accord with the value of 7 7 expected if atmospheric p co 2 and organic matter 13c values were the same for both paleosol types furthermore the atmospheric p co 2 calculated for the early permian from the average measured carbon isotopic compositions of the paleosol calcite and organic matter is also analytically indistinguishable from 1 pal with a maximum calculated atmospheric p co 2 permitted by one standard deviation of the organic matter 13c value of 5 pal if however measured average 13c values of the plant organic matter are more positive than the original soil organic matter as a result of diagenetic loss of 13c depleted labile organic compounds calculated permian atmospheric p co 2 using these 13c enriched organic values would underestimate the actual atmospheric p co 2 using either goethite or calcite this is the first stratigraphically constrained intrabasinal study to compare ancient atmospheric co2 concentrations calculated from pedogenic goethite and calcite these results demonstrate that the two different proxies record the same information about atmospheric co2 the fe co3 oh component in pedogenic goethite from a triassic paleosol in utah is significantly enriched in 13c relative to fe co3 oh in goethites from soils in which there are mixtures of two isotopic co2 components field relationships and the 13c value 1 9 of the triassic goethite indicate that this ancient paleosol profile experienced mixing of three isotopically distinct co2 components at the time of goethite crystallization the three components were probably atmospheric co2 co2 from in situ oxidation of organic matter and co2 from in situ dissolution of preexisting calcite although mixing of three isotopically distinct co2 components as recorded by fe co3 oh in goethite has been described in modern soil this is the first example from a documented paleosol its preservation affirms the need for careful case by case assessment of ancient paleosols to establish that goethite in any particular soil is likely to be a valid proxy of atmospheric p co 2

late pennsylvanian aridification on the southwestern margin of gondwana paganzo basin nw argentina a regional expression of a global climate perturbation abstract paleosols of the paganzo group preserve a shift from the cool climate of the glaciated high latitudes of gondwana to a long term aridification punctuated by shorter term fluctuations in moisture regime in the late carboniferous a quantitative reconstruction of paleoclimate inferred from the major element chemistry of paleosol horizons and the stable isotope geochemistry of soil formed minerals and organic matter indicates that the climate varied substantially during deglaciation along the southwestern margin of gondwana in the middle pennsylvanian including two geologically abrupt shifts to notably drier conditions this dynamic climate terminates in a dry subhumid moisture regime characterized by steppe dry scrub floral provinces quantitative estimates of net primary production during the post glacial interval inferred from paleosol major element geochemistry are consistent with a mesic soil temperature regime in agreement with paleotemperatures inferred from pedogenic goethite d and 18 o contemporaneous aridification is well expressed in paleotropical continental records with middle to late pennsylvanian aridification coincident with an abrupt evolutionary change in many marine and terrestrial species the synchrony of aridification between the high and low paleo latitudes and concomitant major restructuring of some ecosystems suggests that a paleoclimate change of global nature occurred during the moscovian and kasimovian

high precision u pb calibration of carboniferous glaciation and climate history paganzo group nw argentina the duration and geographic extent of carboniferous glacial events in southern gondwana remain poorly constrained despite recent evidence for a more dynamic glacial history than previously considered we report 10 high precision 2 0 1 u pb ages for the permian carboniferous paganzo group nw argentina that redefi ne the chronostratigraphy of the late paleozoic paganzo and rio blanco basins and signifi cantly refi ne the timing of glacial events and climate shifts in the western region of southern gondwana radiometric calibration of the paganzo group indicates three pulses of carboniferous glaciation in the mid visean the late serpukhovian to earliest bashkirian and between the latest bashkirian to early moscovian an abrupt shift in depositional style from high sinuosity single storied fl uvial deposits and clay rich paleosols to low sinuosity multi storied feldspathic fluvial deposits inter calated with eolianites and calcic paleosols is constrained to the latest moscovian and earliest kasimovian these constraints indicate a relatively abrupt climate shift from humid subhumid to nonseasonal semiarid regional climate conditions that occurred signifi cantly earlier than previously inferred early permian this period of high latitude aridity was contemporaneous with a shift to dryland depositional environments and a major vegetation regime shift documented throughout the pangean paleotropics in the pennsylvanian

geocarbsulf a combined model for phanerozoic atmospheric o2 and co2 abstract a model for the combined long term cycles of carbon and sulfur has been constructed which combines all the factors modifying weathering and degassing of the geocarb iii model berner r a kothavala z 2001 geocarb iii a revised model of atmospheric co2 over phanerozoic time am j sci 301 182 204 for co2 with rapid recycling and oxygen dependent carbon and sulfur isotope fractionation of an isotope mass balance model for o2 berner r a 2001 modeling atmospheric o2 over phanerozoic time geochim cosmochim acta 65 685 694 new isotopic data for both carbon and sulfur are used and new feedbacks are created by combining the models sensitivity analysis is done by determining 1 the effect on weathering rates of using rapid recycling rapid recycling treats carbon and sulfur weathering in terms of young rapidly weathering rocks and older more slowly weathering rocks 2 the effect on o2 of using different initial starting conditions 3 the effect on o2 of using different data for carbon isotope fractionation during photosynthesis and alternative values of oceanic 13c for the past 200 million years 4 the effect on sulfur isotope fractionation and on o2 of varying the size of o2 feedback during sedimentary pyrite formation 5 the effect on o2 of varying the dependence of organic matter and pyrite weathering on tectonic uplift plus erosion and the degree of exposure of coastal lands by sea level change 6 the effect on co2 of adding the variability of volcanic rock weathering over time berner r a 2006 inclusion of the weathering of volcanic rocks in the geocarbsulf model am j sci 306 in press results show a similar trend of atmospheric co2 over the phanerozoic to the results of geocarb iii but with some differences during the early paleozoic and for variable volcanic rock weathering lower co2 values during the mesozoic atmospheric oxygen shows a major broad late paleozoic peak with a maximum value of about 30 o2 in the permian a secondary less broad peak centered near the silurian devonian boundary variation between 15 and 20 o2 during the cambrian and ordovician a very sharp drop from 30 to 15 o2 at the permo triassic boundary and a more or less continuous rise in o2 from the late triassic to the present

paleosols as indicators of paleoenvironment and paleoclimate paleosols are ancient soils that have been incorporated into the geological record soils form in response to interactions among the lithosphere hydrosphere biosphere and atmosphere so paleosols potentially record physical biological and chemical information about past conditions near earth s surface as a result paleosols are an important resource for terrestrial environmental and climatic reconstructions long standing paleosol research topics include morphology classification and clay mineralogy all of which provide information about pedogenic processes and local paleoenvironments paleosols are also used to infer processes involved in the development of stratigraphic architecture and basin evolution recent paleosol research has introduced semiquantitative and quantitative measures for environmental and chronometric reconstructions that provide insight into major regional to global changes in temperature precipitation and atmospheric pco2 these new proxies focus on morphological and chemi

a 100 myr history of the carbon cycle based on the 400 kyr cycle in marine δ13c benthic records documenting the past coevolution of earth temperatures and of the carbon cycle is of paramount importance for our understanding of climate dynamics atmospheric co2 is well constrained over the last million years through direct measurements in air bubbles from antarctic ice cores for older times many different and sometimes conflicting proxies have been suggested here we provide a new methodology to constrain the carbon cycle in the past based on marine benthic 13c records marine 13c data are recording a persistent 400 kyr cycle with an amplitude primarily linked to the total amount of carbon in the ocean or dissolved inorganic carbon dic by extracting this amplitude from published records we obtain a new strong constraint on the 100 myr history of earth s carbon cycle the obtained cenozoic evolution of dic is in surprisingly in a good agreement with existing reconstructions of pco2 suggesting that pco2 is mostly driven by dic changes over this period in contrast we find no strong decreasing trend in dic between the cretaceous and the cenozoic suggesting that cretaceous atmospheric pco2 levels were limited and high temperatures at this time should be explained by other mechanisms alternatively high cretaceous atmospheric pco2 could occur as a consequence of changes in oceanic chemistry but not carbon content

soil co2 efflux simulations using monte carlo method and implications for recording paleo atmospheric pco2 in pedogenic gibbsite abstract monte carlo simulation testing of the sensitivity of the fickian diffusion model used for paleo pco 2 proxies indicates that assuming annual average soil respiration rate results in over estimation of pco 2 in all cases the natural variability of the factors of the model including soil porosity and inverse tortuosity and the 13 c value of the soil produced co 2 were not able to account for discrepancies between measured 13 c values from a modern soil and modeled results using established assumptions assuming that there is negligible carbon isotope fractionation during the occlusion of co 2 in pedogenic gibbsite the flaw in the model appears to be the assumed value of soil respiration rate if correct the implication is that previous paleo pco 2 estimates from soil hydroxides may be too high by as much as a factor of ten

seasonal bias in the formation and stable isotopic composition of pedogenic carbonate in modern soils from central new mexico usa in order to better calibrate pedogenic carbonate as a proxy for past environments we compared the stable isotopic composition of soil co 2 soil water and pedogenic carbonate in young soils from central new mexico usa seasonal changes in the 13 c value of soil co 2 the 18 o value of soil water and the soil temperature were monitored to establish the timing of isotopic equilibrium with the carbonate calcite solubility was calculated from measured temperatures and co 2 concentrations in the soil this approach allowed us to determine the conditions associated with pedogenic carbonate formation carbon isotope equilibrium oxygen isotope equilibrium and minimum calcite solubility all occurred simultaneously during warm dry conditions in may 2008 when soil co 2 concentrations were low it is therefore concluded that pedogenic carbonate forms during warm dry periods and does not record mean growing season conditions as typically assumed the seasonal bias in pedogenic carbonate formation may explain the occurrence of pedogenic carbonate in monsoon climates and its absence in regions where annual precipitation is more uniformly distributed the implications of the seasonal bias for stable isotope based paleoenvironmental reconstructions are that paleoelevations may have been previously over or underestimated paleoatmospheric co 2 concentrations likely have been signifi cantly overestimated and pedogenic carbonate provides a c 4 biased record of paleovegetation especially in dry soils

fe co3 oh in goethite from a mid latitude north american oxisol estimate of atmospheric co2 concentration in the early eocene climatic optimum abstract measured mole fractions x and 13c values of the fe co3 oh component in pedogenic goethite from a mid latitude oxisol of early eocene age 52 ma b p range from 0 0014 to 0 0064 and 20 1 to 15 4 respectively these values of x imply that concentrations of co2 gas in the paleosol were 7400 to 34 000 ppm 13c and 1 x are correlated and define a linear soil co2 diffusive mixing line with a positive slope such positive slopes are characteristic of mixing of two isotopically distinct co2 endmembers atmospheric co2 and co2 from oxidation of soil organic matter from the intercept of the mixing line it is calculated that the 13c value of organic matter in the ancient soil was 28 0 the magnitude of the slope implies an early eocene atmospheric co2 concentration of 2700 ppm a simple model for forest soils suggests that a canopy effect may cause atmospheric co2 concentrations deduced from pedogenic minerals to underestimate the actual concentrations of atmospheric co2 if a significant forest canopy were present at the time of formation of pedogenic goethite in the ione fm the concentration of 2700 ppm calculated for atmospheric co2 could be slightly low but the underestimate is expected to be

abyssal eddy kinetic energy levels in the western north pacific abstract an earlier observation of about 50 cm2 s 2 for the maximum abyssal 4000 m depth eddy kinetic energy ke in the western north pacific along 152 e occurring in the vicinity of the kuroshio extension is now supported by nearly two years of observation with moored instruments deployed from 28 to 41 n the maximum occurred at the same site each year nominal from one array setting to the next near 35 n and the composite or two year average is 45 cm2 s 2 at analogous longitudes in the western north atlantic one finds abyssal kinetic energies as high as 100 150 cm2 s 2 in the vicinity of the gulf stream however the abyssal western north pacific could be more energetic at longitudes other than 152 e eddy intensities at abyssal depths near the gulf stream do drop off to smaller values approaching either cape hatteras or longitudes in the vicinity of the grand banks of newfoundland abyssal ke values at specific sites along 152 e were observed to vary by as low as a few percent and as high a