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

deformations and ground temperatures at a road embankment in northern canada the paper examines the behaviour of a highway embankment in an area of discontinuous permafrost about 18 km northwest of thompson manitoba frequent maintenance has been required research involve

a revised relaxation time spectrum for fennoscandia summary the fennoscandian relaxation time spectrum rts first derived by mcconnell 1968 is a classic data set in studies of glacial isostatic adjustment gia we outline a new method for estimating an rts from a set of strandline data which is based on a damped least squares solution for spherical harmonic coefficients associated with the strandline heights in contrast to the hankel transform approach outlined by mcconnell 1968 the method does not require interpolation or extrapolation of the data nor does it use the assumption that peripheral deformations are zero we begin by applying the new approach to a suite of synthetic strandlines these synthetic calculations quantify the effect on the rts estimates of the common assumptions of free decay uplift an axisymmetric fennoscandian deformation field and the uncertainty introduced by limited spatial and temporal sampling of this field recently the accuracy of the sauramo 1958 strandline data upon which the mcconnell 1968 rts was based has been questioned wolf 1996 accordingly we apply our new approach to a set of more robust strandline data published by donner 1964 1969 1980 1995 to compute a revised rts for fennoscandia at high harmonic degrees above 50 our new rts is characterized by weak constraints whereas mcconnell s 1968 rts suggests a significant reduction in relaxation times relative to the values at low degrees this reduction was the basis for mcconnell s 1968 inference of an elastic lithosphere in contrast to this we conclude that the trend is an artefact of the observational data set he adopted at lower degrees mcconnell s 1968 relaxation time estimates lie at the lower end of the range implied by the present analysis to complete our study we apply the techniques of linearized bayesian inference to invert our newly derived rts for mantle viscosity we find that the rts provides an estimate of 5 1020 pa s for the volumetric mean viscosity in a region extending from the base of the lithosphere to about 550 km depth target regions which extend from the transition zone to 1200 km depth are less well constrained however the average viscosity from the base of the lithosphere to 1200 km depth is consistent with the classic haskell 1935 value of 1021 pa s for mantle viscosity finally we demonstrate that viscosity models within the class inferred by mitrovica forte 1997 from joint inversions of postglacial relaxation times associated with gia and mantle convection observables simultaneously fit the revised fennoscandian rts

model test on partial expansion in stratified subsidence during foundation pit dewatering abstract partial expansion was observed in stratified subsidence during foundation pit dewatering however the phenomenon was suspected to be an error because the compression of layers is known to occur when subsidence occurs a slice of the subsidence cone induced by drawdown was selected as the prototype model tests were performed to investigate the phenomenon the underlying confined aquifer was generated as a movable rigid plate with a hinge at one end the overlying layers were simulated with remolded materials collected from a construction site model tests performed under the conceptual model indicated that partial expansion occurred in stratified settlements under coordination deformation and consolidation conditions during foundation pit dewatering rapid drawdown resulted in rapid subsidence in the dewatered confined aquifer the rapidly subsiding confined aquifer top was the bottom deformation boundary of the overlying layers non coordination deformation was observed at the top and bottom of the subsiding overlying layers the subsidence of overlying layers was larger at the bottom than at the top the layers expanded and became thicker the phenomenon was verified using numerical simulation method based on finite difference method compared with numerical simulation results the boundary effect of the physical tests was obvious in the observation point close to the movable endpoint the tensile stress of the overlying soil layers induced by the underlying settlement of dewatered confined aquifer contributed to the expansion phenomenon the partial expansion of overlying soil layers was defined as inversed rebound the inversed rebound was induced by inversed coordination deformation compression was induced by the consolidation in the overlying soil layers because of drainage partial expansion occurred when the expansion exceeded the compression considering the inversed rebound traditional layer wise summation method for calculating subsidence should be revised and improved

modelling of viscous effects in natural clays a new approach to allow the modelling of the viscous behaviour of natural clay soils including creep stress relaxation and the effects of applied strain rate on soil stiffness has been developed based on the brick constitutive model published by simpson in 1992 the new model strain rate dependent srd brick was used in a series of simulations to demonstrate its capabilities in predicting realistic behaviour during one dimensional compression and undrained triaxial tests in which applied strain rates were varied triaxial stress path tests conducted by gasparre et al in 2007 to assess the influence of creep resulting from recent stress history on soil stiffness were also simulated the observed trends concerning the stiffness at small strains were successfully modelled

chemistry of modern soils as a guide to interpreting precambrian paleosols precambrian paleosols are potentially one of our best sources of information about the composition of the atmosphere early in earth s history to be used this way however an alteration profile must be shown to be an in situ product of vadose processes data from modern soils show that the ratios of less mobile elements such as zr ti and al can be used as a preliminary screen to test for the in situ nature of a profile if the ti zr ratio departs from that of the host rock by more than 40 or the ti al ratio departs by more than 50 for moderate degrees of weathering then a significant allochthonous contribution to the profile is indicated this technique correctly separates in place from allochthonous horizons when applied to independent data from two modern profiles a review of published precambrian profiles identifies two often cited examples denison and pronto as suspect based on these criteria in the interpretation of paleoatmospheres it is also necessary to show that fe is controlled not b

hydrogen isotopes in eocene river gravels and paleoelevation of the sierra nevada we determine paleoelevation of the sierra nevada california by tracking the effect of topography on precipitation as recorded in hydrogen isotopes of kaolinite exposed in gold bearing river deposits from the eocene yuba river the data compared with the modern isotopic composition of precipitation show that about 40 to 50 million years ago the sierra nevada stood tall 2200 meters a result in conflict with proposed young surface uplift by tectonic and climatic forcing but consistent with the sierra nevada representing the edge of a pre eocene continental plateau

biomarker reconstruction of the early eocene paleotopography and paleoclimate of the northern sierra nevada we reconstruct ancient temperature and elevation gradients across the early eocene 52 49 ma northern sierra nevada california united states using organic molecular proxies that record atmospheric and ground level effects of topography paleoelevation was determined by reconstructing the change in the hydrogen isotopic composition of precipitation d precip and mean annual temperature t gdgt glycerol dialkyl glycerol tetraethers from the isotopic composition of fossil angiosperm leaf n alkanes and the distribution of microbially produced soil tetraethers preserved in leaf bearing sediments organic molecular data produce equivalent range scale d n alkane and channel t gdgt paleoelevation estimates that show the northern sierra nevada was a warm 6 8 c warmer than modern high elevation 2 km and moderate to low relief landscape at the eocene climatic optimum modern northern sierra nevada topography likely refl ects post paleocene reduction of mean surface elevation and late cenozoic increases in relief

the present rate of uplift of fennoscandia implies a low viscosity asthenosphere the rate of displacement in fennoscandia has been intensively discussed for many years it is now widely accepted to be an isostatic response of the glacial history of the area the earth s present response to deglaciation in fennoscandia is simulated using a three dimensional 3d viscoelastic model in which the asthenosphere and mantle viscosity are allowed to vary so that the maximum rate of present uplift matches its observed value the deglaciation history is considered to be known and the c14 datings are converted to sidereal years the pattern of the present uplift gives a firm match with the observed data when a low viscosity asthenosphere is introduced assuming a 15 000 years load cycle i e the glacier was applied to the surface for 15 000 years before the melting started the best fitting earth viscosity model is a 1024 nm lithosphere overlying a 75 km thick 2 0 1019 pas asthenosphere and a 1 2 1021 pas mantle the simulations suggest a remaining maximum uplift of 40 m

comment on the inference of mantle viscosity from an inversion of the fennoscandian relaxation spectrum by j x mitrovica and w r peltier mitrovica peltier 1993 hereafter mp have recently analysed the fennoscandian uplift data using inversion techniques they concluded that although observations support the presence of a weak asthenosphere under fennoscandia the decay spectrum for the best fit model 1 3 x lo1 pa s asthenosphere overlying a 10zlpas mantle found by previous workers fjeldskaar cathles 1991a b cathles 1975 1980 hereafter fc lies outside the decay spectrum observed in fennoscandia and is thus excluded by the observed data we believe this conclusion results from the authors inadvertantly using a different asthenosphere thickness in their calculations than the one that they report the purpose of this communication is to argue this case and to show that when proper asthenosphere thicknesses are used the models of mp and fc are both compatible with the observed uplift data and that each in fact defines one edge of the observed uplift spectrum the essential difference in the two end member models is the elected tradeoff between lithosphere thickness and asthenosphere viscosity mp choose a stiff lithosphere and a minor asthenosphere whereas fc choose the opposite we believe lithosphere rigidity data not discussed in mp argue for a weak lithosphere in fennoscandia and suggest that the fc model is to be preferred the relaxation spectrum for the best fit model of fc as presented in m p s fig 11 is shown by the dashed curve labelled lvz in fig 1 it clearly lies below and outside the observed fennoscandian relaxation data shaded area the decay spectrum for the lvz model is according to mp based on loading of a 70 km lithosphere on a 90 km asthenosphere of viscosity 2 x lo pa s overlying a 10 p a s mantle the maximum relaxation time for the lvz model exceeds 6000 years however the maximum relaxation time for fc s bestfit asthenosphere model that the lvz curve is supposed to

late oligocene to early miocene humidity change recorded in terrestrial sequences in the ili basin south eastern kazakhstan central asia enhanced aridification of central asia driven by the combined effects of orogenic surface uplift paratethys retreat changes in atmospheric moisture transport and global cooling is one of the most prominent cenozoic climate change events of the northern hemisphere deciphering regional long term patterns of central asian hydrology is therefore a key element in understanding the role of northern hemisphere mid latitude drying in the global hydrological system this study characterizes long term palaeoenvironmental conditions between the late oligocene and early miocene in south eastern kazakhstan based on stable isotopes elemental geochemistry and laser ablation uranium lead geochronology from alluvial fluvial and pedogenic deposits sedimentary facies and geochemical weathering indices suggest an increased surface and ground water discharge fed by orographically enhanced precipitation in the tien shan hinterland in contrast pedogenic stable isotope data and elevated rates of magnesium fixation in clay minerals mirror enhanced rates of evaporation in the vadose zone due to protracted aridification this study posits that pronounced surface uplift of the tien shan mountains during the oligocene miocene transition promoted regionally increased orographic precipitation and the development of fluvial discharge systems this article is protected by copyright all rights reserved

finite element analysis of an embankment on a soft estuarine deposit using an elastic viscoplastic soil model a new elastic viscoplastic evp soil model has been used to simulate the measured deformation response of a soft estuarine soil loaded by a stage constructed embankment the simulation incorporate

flexural rigidity of fennoscandia inferred from the postglacial uplift the earth s response to glacial loading unloading offers exceptional promise for the study of the physical properties of the lithosphere in particular tilting of paleoshorelines is very sensitive to the lithosphere rigidity to determine the flexural rigidity the isostatic response to deglaciation in fennoscandia is modeled using an earth model with a layered mantle viscosity overlain by an elastic lithosphere the flexural rigidity and asthenosphere viscosity is allowed to vary to get a match between theoretical and observed present rate of uplift and tilting of paleoshorelines five different ice thickness models are used for a relatively thin ice 2500 m in central areas the resulting flexural rigidity is more or less uniform over fennoscandia with a value of 1023 n m elastic thickness te 20 km this is regarded as minimum for the flexural rigidity of central fennoscandia the pattern of the present rate of uplift and the tilts of the paleoshorelines of the area also sets an upper bound of the flexural rigidity 2 5 1025 n m te 110 km in more central areas of fennoscandia the flexural rigidity at the western coast of norway does not seem to exceed 1023 n m te 50 km the most likely glacier model gives a flexural rigidity of 1023 n m te 20 km at the norwegian coast increasing to above 1024 n m te 50 km in central parts of fennoscandia

effects of principal stress rotation on the cumulative deformation of normally consolidated soft clay under subway traffic loading abstractthe authors investigated the effects of principal stress rotation psr on the traffic load induced settlement of subways in soft subsoil here a series of hollow cylinder tests on normally consolidated medium plasticity soft clay with and without principal stress rotation were performed along with finite element modeling and simulation the results show significant increases in both excess pore water pressure and cumulative deformation of the normally consolidated soft clay when psr is present and simulated and the effects become more pronounced as the maximum effective principal stress ratio or load frequency increases under the actual traffic load induced stress in subsoil below the subway tunnel the presence of psr increases the cumulative deformation of soft clay by 9 23 compared with that without psr as an approximation the cumulative deformation of soft clay with the effect of psr can be estimated by multiplying the deformation derived from the repeated triaxial testing without psr

a paleopedological and ichnological approach to interpreting spatial and temporal variability in early permian fluvial deposits of the lower dunkard group west virginia u s a abstract lower permian asselian deposits of the washington formation dunkard group in west virginia u s a represent proximal to distal expressions of a migrating anastomosing river and associated floodplain environments these deposits are part of the upper fluvial plain province of the dunkard basin characterized by thick to thin sandstone bodies shales and paleosols the paleosols and associated ichnofossils record a wealth of paleoenvironmental paleoecological and paleoclimatic data which improve our understanding of the autogenic and allogenic processes that result in the spatial and temporal variability of ancient fluvial systems this study integrates field and laboratory analysis of paleosols and ichnofossils including macro to micromorphology bulk geochemistry and clay mineralogy to better understand variations in soil forming processes across this early permian floodplain nine different pedotypes were identified including proximal poorly developed entisols and inceptisols poorly drained histosols and thick moderately to well drained inceptisols and vertisols lateral differences in paleosol properties were minor compared to the diversity of paleosols present in the vertical exposure and were largely a result of localized variations in drainage and topography differences in the properties of the paleosols in the vertical succession could not be explained by variable drainage due to position on the floodplain cyclicity was largely controlled by avulsion but was overprinted by changes in climate while climatic drying during the early permian as a general trend is well established smaller scale fluctuations between wet and dry intervals contributed significantly to observed paleosol properties dominance by calcareous vertisols in the upper fluvial plain facies province and their representation of strongly seasonal conditions are consistent with previous research however thorough investigation of the paleosols suggests that more humid conditions existed than the arid to semiarid climate that has been suggested

transient drying during the paleocene eocene thermal maximum petm analysis of paleosols in the bighorn basin wyoming abstract the paleocene eocene thermal maximum petm was a transient episode of global warming that occurred at the paleocene eocene boundary the event is marked by a sharp decline in carbon isotope values that is globally recognized from marine and continental sections the negative isotope excursion has been attributed to the release of methane hydrates from oceanic sediments although studies concur that temperatures rose during the petm changes in precipitation are not well understood alluvial paleosols in the bighorn basin that span the petm interval contain a continuous and highly resolved record of climate including information on precipitation they show a significant but transient decrease in precipitation at the onset of the petm but a gradual return to pre petm levels by the end of the interval the paleosols also show additional although less dramatic wet dry cycles within the petm interval that may correspond to precessional cycles that have been identified in the marine record of the petm this study counters interpretations of increased precipitation for wyoming at this time and shows the importance of detailed case studies of continental strata to test climatic generalizations and models that have been developed for petm precipitation patterns

the cenozoic climatic and topographic evolution of the western north american cordillera herein we present oxygen isotope records from cretaceous to recent terrestrial sediments in the western north american cordillera the purpose of this analysis is to use oxygen isotope records to understand the coupled surface elevation and climate histories of this region through the cenozoic to do this we constructed 18o maps of surface waters for time intervals that trace the development of topography of western north america these maps are based on 4861 oxygen isotope analyses from both published 4478 and new 383 data we determined the 18o values of surface waters using paleotemperatures derived previously from floral assemblages and the appropriate isotope fractionation factors these data suggest that in the late cretaceous to early eocene the sevier hinterland formed a plateau of unknown height around 50 ma a topographic wave developed in british columbia and eastern washington that swept southward reaching northeastern nevada at 40 to 38 ma and southern nevada 23 ma this southward encroachment of an eocene plateau sweep caused reorganization of drainage patterns such that the intraforeland basins of wyoming and utah drainages extended deep within the sevier hinterland as the wave swept southward the landscape within the sevier hinterland developed into a rugged and high mountain range with the hypsometric mean elevation of 4 km and relief of 1 5 km this eocene highland was bordered on the west by a high sierra nevada ramp and on the east by the intraforeland basins that captured water draining these growing highlands the spatial and temporal evolution of this highland correlates with the timing of volcanism and extension these observations support tectonic models that call for north to south removal of the farallon slab or piecemeal removal of mantle lithosphere the isotopic data show that prior to growth of this highland the north american monsoon nam penetrated much farther north in the paleocene eocene than today the combined effects of global cooling increasing latitudinal temperature gradients and the generation of the orographic barrier created by the growing north to south highland produced a southward migration of the nam front by the oligocene the hydrologic regime that we observe today was in place it has been modified since then as a result of basin and range extension and collapse of the highlands in the mid miocene this collapse allowed the nam to penetrate farther north into the great basin of nevada and utah

a soil chronosequence in the semi arid environment of patagonia argentina abstract soil development with time was investigated on beach ridges with ages ranging from about 1380 to 6240 14c years bp at the eastern coast of central patagonia the main pedogenic processes are accumulation of organic matter and carbonate leaching and accumulation within the upper part of the soils soil formation is strongly influenced by incorporation of eolian sediments into the interstitial spaces between the gravel of which the beach ridges are composed different amounts of eolian material in the soils lead to differentiation into leptosols containing 10 fine earth in the upper 75 cm and regosols containing 10 fine earth soil depth functions and chronofunctions of organic carbon calcium carbonate ph ca zr mg zr k zr na zr fe zr mn zr and si al obtained from x ray fluorescence analysis were evaluated to establish soil chronofunctions mean values of the horizon data of 0 10 cm below the desert pavement were used which were weighted according to the horizon thicknesses the depth function of ph shows a decrease towards the surface indicating leaching of bases from the upper centimeters chronofunctions of ph show that within 6000 radiocarbon years of soil development ph drops from 7 0 to 6 6 in the leptosols and from 8 1 to 7 5 in the regosols the higher ph of the regosols is due to input of additional bases from the eolian sediments chronofunctions of ca zr and k zr indicate progressive leaching of ca and k in the regosols showing close relationships to time r2 0 972 and 0 995 na leaching as indicated by decreasing na zr ratios shows a strong correlation to time only in the leptosols r2 0 999 both leptosols and regosols show close relationships to time for fe zr r2 0 817 and 0 824 mn zr r2 0 940 and 0 803 and si al 0 971 and 0 977 indicating enrichment of fe and mn and leaching of si leaching of mobile elements takes place on a higher level in the regosols than in the leptosols from the beginning of soil formation hence a significant part of the eolian sediments must have been incorporated into the beach ridges very soon after their formation

a new elastic viscoplastic model for time dependent behaviour of normally and overconsolidated clays theory and verification this paper presents a new three dimensional elastic viscoplastic 3d evp constitutive model for the time dependent stress strain behaviour of both normally consolidated and overconsolidated clays there are two major new developments in the 3d evp model i incorporation of a nonlinear creep function with a limit for the creep volume strain under isotropic stressing conditions ii adoption of a new loading surface function with a smooth shape on the plane based on the equivalent time concept of yin and graham the formulation of the new 3d evp model is derived using the new nonlinear creep function and loading surface function a new approach to determining all model parameters is presented the 3d evp model is calibrated using data from one conventional isotropic stress creep test and consolidated undrained triaxial tests on soft hong kong marine deposits hkmd the model is verified by comparing model results with those from both normally and overconsolidated triaxial tests on hkmd and a mixtu

paleoenvironmental and paleoclimatic interpretations of the late paleocene goler formation southern california u s a based on paleosol geochemistry the paleocene was characterized by high global temperatures and elevated concentrations of atmospheric co2 paleoclimate records of this epoch are of particular interest to understanding the effects of anthropogenic climate forcing as well as linkages between the paleocene climate and major tectonic and evolutionary events however terrestrial paleoclimatic records of the paleocene are limited in their spatial extent and few such records are known from western north america in this study paleosols from two members in the late paleocene goler formation of southern california were used to investigate local paleoclimatic conditions the paleosols were described in detail and analyzed for morphology clay mineralogy and bulk geochemistry carbonate nodules present in paleosols from the upper member member 4a were characterized using petrographic and cathodoluminescence microscopy and were analyzed for carbon and oxygen stable isotope composition enrichment and retention of soluble elements ca mg and na and the mobilization of fe and mn in the paleosol profiles suggest a climate with strongly seasonal precipitation this interpretation is further supported by the presence of pedogenic slickensides and the clay minerals smectite and illite the appearance of pedogenic carbonate nodules in paleosols from the upper member is suggestive of a shift to more arid or more seasonal conditions that is coincident with a prominent change in sediment provenance and an inferred increase in sedimentation rate uplift of the ancestral sierra nevada during the late paleocene was likely an important control on regional paleoclimate due to the effects of elevated topography on mean annual precipitation and seasonal distribution of precipitation the correlation of a shift in pedogenic processes with changes in provenance and sedimentation rate suggests that the evolution of regional tectonic activity was an important control on these processes during the deposition of the goler formation

sands subjected to repetitive vertical loading under zero lateral strain accumulation models terminal densities and settlement geosystems often experience numerous loading cycles plastic strain accumulation during repetitive mechanical loads can lead to shear shakedown or continued shear ratcheting in all cases volumetric strains diminish as the specimen evolves towards terminal density previously suggested models and new functions are identified to fit plastic strain accumulation data all accumulation models are formulated to capture terminal density volumetric strain and either shakedown or ratcheting shear strain repetitive vertical loading tests under zero lateral strain conditions are conducted using three different sands packed at initially low and high densities test results show that plastic strain accumulation for all sands and density conditions can be captured in the same dimensionless plot defined in terms of the initial relative density terminal density and ratio between the amplitude of the repetitive load and the initial static load this observation allows us to advance a simple but robust procedure t

depth to pedogenic carbonate horizon as a paleoprecipitation indicator an analysis of 1168 modern soil profiles from the u s natural resources conservation service yields no correlation between mean annual precipitation and depth to the top of the carbonate horizon r 2 0 03 p 0 001 parent material and soil texture both play negligible roles in this regression when combined with similar published studies n 1481 r 2 improves slightly r 2 0 31 p 0 001 caution is therefore advised in using this or any previously published regression for inferring paleoprecipitation from paleosols however in the combined data set carbonate horizon bearing soils correlate with a mean annual precipitation of 760 mm p 0 05 thus the presence vs absence of pedogenic calcium carbonate is a good indicator of paleoprecipitation above or below this value

experimental study on the vertical deformation of sand caused by cyclic withdrawal and recharging of groundwater fast urban growth and an ever increasing frequency of extreme weather related events demand a better understanding of land subsidence and the potential measures to control it this paper presents an experimental investigation on the deformation behavior of sand undergoing cyclic withdrawal and recharging of groundwater a sand box model with dimensions 1000 mm 600 mm 892 mm was used to investigate soil deformation following lowering and rising of the water table the sand used was pingtan sand fujian china a quartzitic formation composed of elongated to slightly spherical grains three sand samples with different initial densities i e loose medium dense and dense were tested on repeated cycles the vertical deformation of the sand was measured and the corresponding strain and effective stress were calculated the observations show that initially the sand behaves as an elastic material with the subsidence caused by water withdrawal being recovered as the soil rebounds during recharging with further withdrawal recharging cycles subsidence becomes larger as plastic deformations as well as time dependent deformation occur in the soil the distinct patterns of deformation were identified to be dependent on both the initial density and the number of withdrawal recharging cycle the sand has been subjected to the different behavior of the medium dense sample compared to the loose and dense samples in particular for the first two cycles indicates that the soil response cannot be explained in respect of the initial void ratio alone and further microstructure considerations were discussed it is suggested that the orientation of the grains resulting from the sample preparation technique and the consequent induced anisotropy can be used to explain the results herein presented finally this paper provides the rationale for a micromechanical interpretation of soil deformation when subjected to changes in stress due to rising or lowering of the water table which will help in establishing measures to control land subsidence in particular to assess the efficiency of water recharging following subsidence by withdrawal

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

k o ocr relationships in soil the relationships between k o and ocr are investigated for primary loading unloading reloading conditions the study reviews laboratory data from over 170 different soils and presents an approach common to clays silts and sands simple empirical methods for predicting k o for normally consolidated and overconsolidated soils are evaluated the validity of the methods is supported by statistical analyses on the basis of the findings only the effective stress friction angle o and prior stress history ocr and ocrmax are needed to predict approximate values of k o

centrifuge modeling of land subsidence caused by the high rise building group in the soft soil area with the increase of the high rise buildings land subsidence induced by human activities becomes a major problem land subsidence occurs slowly but the accumulation results in the cracks in the road the damage to the pipelines and in the tilting or the cracking of the buildings with the withdrawal of groundwater controlled reasonably the engineering environmental effect of the dense high rise building group comes to be the main cause of land subsidence based on the high rise building group in the soft soil area in shanghai the mechanism of land subsidence is studied in this paper by the centrifuge model tests the central area of the building group has larger subsidence and the subsidence superimposition effect is obvious it can exceed the allowance and cause land subsidence hazard the land subsidence affected by the different building distances is also studied for smaller building distances the subsidence superimposition effect is more obvious the larger excess pore water pressure in the pile base supporting layer of the central area shows that the stress superimposition effect is larger the earth pressure under the buildings fluctuates by the disturbance of the pile tips

petrography and geochemistry of floodplain limestones from the clarks fork basin wyoming u s a carbonate deposition and fossil accumulation on a paleocene eocene floodplain abstract floodplain limestones are increasingly important sources of fossil vertebrates from the clarks fork basin the northern extension of wyoming s bighorn basin despite their importance for understanding paleogene floodplain faunas little work has addressed the depositional history of these carbonates or evaluated potential taphonomic biases affecting the assemblages they produce recent studies of bighorn basin paleosols have increased our understanding of parameters affecting the paleo floodplain and large collections of limestones now exist this has allowed detailed investigation of limestone petrography and geochemistry and the proposal of a new model for their formation floodplain limestones record a complex depositional and diagenetic history precipitation of micritic low mg calcite and accumulation of bone occurred in low energy ponded water at the earth s surface pedogenic overprinting obscured primary textures and produced diagenetic grainstones packstones and wackestones biological and chemical pedogenic processes formed most carbonate allochems including micrite grains and calcified plant cells microbial fermentation occurred at shallow burial depths and methane production migration and oxidation affected the carbon isotope composition of diagenetic carbonate and primary micrite pore space was fully occluded by phreatic calcite cements during late stage diagenesis fossil assemblages contained within the limestones likely represent fauna derived from rarely sampled floodplain microenvironments hydraulic transport of bones was minimal accumulation of fossil material occurred episodically and bones were rapidly encased in micrite the uncommon body size distribution characteristic of limestone faunas is attributed in part to buffering of chemical and physical processes normally effecting bone decomposition during surface exposure and pedogenesis

the inference of mantle viscosity from an inversion of the fennoscandian relaxation spectrum summary a formal inverse theory for mantle viscosity is here applied to a relaxation spectrum derived from the post glacial uplift of fennoscandia the spectrum represents the set of eigenfrequencies or inverse decay times for the fundamental mode of viscous gravitational relaxation between the spherical harmonic degrees 14 to 45 and 65 to 80 theoretical predictions of the eigenfrequencies are based upon the determination of the zeroes of the secular determinant function derived for a spherically symmetric self gravitating visco elastic planet differential kernels relating shifts in the eigenfrequencies to arbitrary perturbations in the radial viscosity profile i e frechet kernels are computed using the variational principle derived by peltier 1976 the inversions are performed within the framework of non linear bayesian inference and the problem has been parameterized in terms of the logarithm of viscosity the inversions have yielded a set of robust constraints which all models for the radial viscosity profile below fennoscandia must satisfy the a posteriori estimates and variance reduction are found to be insensitive to the a priori variance ascribed to the model layers the constraints have furthermore been summarized into a set of a posteriori estimates of the average model viscosity value in radial regions consistent with the resolving power of the data which decreases from a radial length scale of approximately 120km at the base of the lithosphere to 1200km at 1000km depth the data provide essentially no information regarding the mantle rheology below 1200km depth for example for earth models with a lithospheric thickness lt of 100 km the volumetric average logarithm of viscosity in regions in the depth ranges 1040 400 km 670 210 km and 235 100 km is constrained to be respectively 21 03 0 09 20 70 0 08 and 20 37 0 19 we have repeated the inversions for a number of assumed lithospheric thicknesses and have found that a relatively low viscosity layer in the sublithospheric region with respect to the underlying upper mantle is required for lt 120km in this respect we have quantified the previously described trade off between a decrease in the viscosity of this region and a decrease in lt cathles 1975 in forward analyses of the glacial isostatic adjustment data set it is common to use earth models with isoviscous upper and lower mantle regions to investigate this two layer case we have also performed inversions which assume perfect correlation amongst the model layers in the upper and separately the lower mantle under this strict model space limitation the inversions yield models with upper and lower mantle viscosities in the range 3 7 1020 4 5 1020 pa s and 2 2 1021 1 9 1021 pa s respectively the ranges are obtained from a suite of inversions using lithospheric thickness from 70 km to 145 km the a posteriori constraints generated from the bayesian inversions are used together with a statistic based on the computed misfit to the fennoscandian relaxation spectrum to rule out a number of previously published viscosity models

viscosity and thickness of the asthenosphere detected from the fennoscandian uplift the earth s response to the deglaciation in fennoscandia is modelled using a layered viscous model with an elastic lithosphere the modelled tilting of palaeoshorelines at particular locations peripheral to the former ice load and the pattern of the present rate of uplift consistent with the observations strongly suggest a low viscosity asthenosphere earth models without a low viscosity asthenosphere give significant mismatch to the present rate of uplift and are unable to mimic the observed tilting of palaeoshorelines models with a viscosity of the lower mantle of 1 0 2 0 1021 pa s and a viscosity of the upper mantle of 0 7 1 0 1021 pa s overlain by low viscosity asthenosphere with a thickness ranging from 25 to 100 km fit equally well with the observations it is suggested strongly that the asthenosphere has a thickness of less than 150 km and a viscosity of less than 7 0 1019 pa s

paleosol and dolocrete associated clay mineral occurrences in siliciclastic red sediments of the late miocene komisini formation of the tuzgolu basin in central turkey abstract the late miocene was characterized by high global temperatures and partly to nearly complete desiccation of the mediterranean sea throughout the latter part of the messinian age the messinian salinity crisis the late miocene marine mediterranean sea area has been widely studied from different perspectives but terrestrial paleoenvironmental and paleoclimatic records from the mediterranean area are highly limited in their spatial range to this end the paleosols dolocrete and fluvial sedimentary rocks of the komisini formation in the northwestern part of the tuzgolu basin are described in detail six lithofacies were identified as a clast supported gravel b massive pebbly sandstone c massive mudstone d disrupted mud e disrupted conglomerate and f disrupted matrix supported conglomerate the siliciclastic facies were interpreted as braidplain and the distal part of braidplain deposits is associated with an ophiolitic area while the disrupted mud and disrupted conglomerate were identified as three types of paleosols inceptisols aridisol and vertisols the calcretes occur in the paleosols in nodular powder and massive forms clay minerals include smectite chlorite palygorskite illite and serpentine gypsum smectite and chlorite are dominant minerals at the base and middle part of the section whereas palygorskite and illite appear as the prevailing clay minerals in the upper sections smectite illite and palygorskite precipitated in a vadose zone from strongly evaporated alkaline water rich in si ca and mg and poor in al at increased temperatures and at an advanced stage of dolocrete and paleosol formation k si mg al fe and ca are required for smectite illite palygorskite and calcification given the increase in ba cr ni and co these cations might have originated from ophiolite carbonate and volcanic units as a consequence the vertical distribution of clay mineral types suggests the variations of paleoclimatic conditions during the deposition and the relationships among the type of host rock paleosol and dolocrete which corresponds to nearly complete desiccation of the mediterranean sea

determining terrestrial paleotemperatures using the oxygen isotopic composition of pedogenic carbonate abstract quantifying terrestrial paleotemperatures has proven to be a challenging endeavor this paper explores the use of the oxygen isotopic composition of pedogenic calcite for terrestrial paleotemperature reconstructions we generate three paleotemperature equations two of them derived by simultaneous solution of equations that describe the fractionation of oxygen isotopes in the exogenic cycle while the third equation is derived using a linear regression through modern 18occ mat oxygen isotopic composition of pedogenic calcite versus mean annual temperature data we use the paleotemperature equations to evaluate climate change across the k t boundary by analyzing the oxygen isotopic composition of pedogenic carbonates from a series of stacked paleosols in west texas the fabrics in the calcite nodules were evaluated in order to identify soil carbonate components that have the best chance of containing isotopic information that represents ancient pedogenic conditions the average temperature for west texas during the time period studied is 18 0 5 c two temperature excursions are recognized prior to the k t boundary in which terrestrial temperatures increase by about 4 c for relatively short periods of time these short greenhouse events documented in west texas correlate with changes in marine temperatures as well as terrestrial temperatures in north dakota during the same time period latitudinal temperature gradients generated using the west texas and north dakota data indicate that the spatial simultaneous solution yields the most reliable temperature reconstructions of the three equations considered in this study

formation of clay minerals in soils developed from basic volcanic rocks under semiarid climatic conditions in lanzarote spain abstract clay formation in soils was studied in four landscapes of different ages in lanzarote canary islands landscape iv b is about 250 years old iv a subrecent iii early young pleistocene and landscape i late tertiary the soils have developed from basic to ultrabasic pyroclastic fall deposits or basalt clay formation in soils of landscape iv b is in an initial stage having a clay content of 1 2 kg m 2 whereas in landscape iv a 30 40 kg m 2 and in landscape iii 100 200 kg clay m 2 are accumulated in polygenetic soils of landscape i more than 3000 kg clay m 2 can be found in the youngest soils iv b smectite is the most prominent clay mineral whereas iv a soils are dominated by amorphous clay the clay fraction in older soils contains illite smectite as well as kaolinite in smaller quantities the chemical composition of the clay fraction of soils with different ages changes significantly according to the mineral composition

uranium lead isotopic ages from the sierra nevada batholith california this study provides new information on the timing and distribution of mesozoic magmatic events in the sierra nevada batholithic complex chiefly between 36 and 37 n latitude u pb ages have been determined for 133 zircon and 7 sphene separates from 82 samples of granitoid rocks granitoid rocks in this area range in age from 217 to 80 m y triassic intrusions are restricted to the east side of the batholith jurassic plutons occur south of the triassic plutons east of the sierra nevada as isolated masses within the cretaceous batholith and in the western foothills of the range cretaceous plutons form a continuous belt along the axis of the batholith and occur as isolated masses east of the sierra nevada no granitic intrusions were emplaced for 37 m y east of the sierra nevada following the end of jurassic plutonism however following emplacement of the eastern jurassic granitoids regional extension produced a fracture system at least 350 km long into which the dominantly mafic calc alkalic independence dike swarm was intruded 148 m y ago the dike fractures probably represents a period of regional crustal extension caused by a redistribution of the regional stress pattern accompanying the nevadan orogeny intrusion of cretaceous granitic plutons began in large volume about 120 m y ago in the western sierra nevada and migrated steadily eastward for 40 m y at a rate of 2 7 mm y this slow and constant migration indicates remarkably uniform conditions of subduction with perhaps downward migration of parent magma generation or a slight flattening of the subduction zone such steady conditions could be necessary for the production of large batholithic complexes such as the sierra nevada the abrupt termination of plutonism 80 m y ago may have resulted from an increased rate of convergence of the american and eastern pacific plates and dramatic flattening of the subduction zone u pb ages of the giant forest alaskite sequence in sequoia national park are all in the range 99 3 m y indicating a relatively short period of emplacement and cooling for this nested group of plutons u pb ages of a mafic inclusion and its host granodiorite indicate that both were derived from a common source or that the mafic inclusion was totally equilibrated with the granodioritic magma comparison of isotopic ages determined by different methods such as zircon u pb sphene u pb hornblende k ar and biotite k ar suggests that zircon u pb ages generally approximate the emplacement age of a pluton however some plutons probably contain inherited or entrained old zircons and the zircons of some samples are disturbed by younger thermal and metamorphic events the ages reported here are consistent with u pb age determinations previously made on granitic rocks to the north stern et al 1981 the age distribution of granitic belts determined here is in general agreement with those established by k ar dating evernden and kistler 1970 but does not differentiate the five epochs of plutonism determined in their study

measurement requirements for glacial uplift detection of nonadiabatic density gradients in the mantle recent isotope studies have rekindled interest in the possibility that the mantle may be chemically stratified and therefore nonadiabatic previous calculations of the last ice age are compatible only with a 1022p mantle calculations of the isostatic response of an adiabatic partially nonadiabatic and fully nonadiabatic 1022p mantle to the load cycle of the last ice age show that the uplift responses of an adiabatic and even partially nonadiabatic mantle are very different however geoid perturbations mask these differences and the emergence curves of the two mantle types are nearly identical except in the regions near and under the ice loads at the early stages of isostatic readjustment the calculations suggest that we must seek shoreline emergence data around glaciated areas more than 6000 years before present if nonadiabatic density gradients in the mantle are to be detected from emergence data

predictions of antarctic crustal motions driven by present day ice sheet evolution and by isostatic memory of the last glacial maximum detectable crustal motion and secular rate of change of solid surface gravity may be produced by the earth s response to present day and past ice mass changes in antarctica scenarios of present day ice mass balance previously utilized to explore the global geodetic signatures of the antarctic ice sheet produce elastic crustal responses that are typically bounded by uplift rates 5 mm yr horizontal motion 1 mm yr and solid surface gravity change rates 1 gal yr in a restricted locality one scenario produces uplift rates slightly in excess of 10 mm yr and correspondingly enhanced horizontal and gravity rates in contrast the viscoelastic response to ice mass changes occurring since last glacial maximum lgm exceeds 5 mm yr uplift over substantial portions of west antarctica for a wide range of plausible choices of timing and magnitude of deglaciation and mantle viscosity similarly viscoelastic gravity rate predictions exceed 1 gal yr decrease over large regions confirming suggestions that a global positioning system gps and absolute gravity based program of crustal monitoring in antarctica could potentially detect postglacial rebound a published revision to the climap model of the antarctic ice sheet at lgm herein called the d91 model features a substantially altered west antarctic ice sheet reconstruction this revision predicts a spatial pattern of present day crustal motion and surface gravity change that diverges strikingly from climap based models peak d91 crustal rates assuming deglaciation begins at 12 kyr and ends at 5 kyr are around 16 mm yr uplift 2 mm yr horizontal and 2 5 gal yr gravity tabulated crustal response predictions for selected antarctic bedrock sites indicate critical localities in the interior of west antarctica where expected responses are large and d91 predictions differ from climap based models by a factor of 2 or more observations of the postglacial rebound signal in antarctica might help constrain antarctic mass balance and contribution to sea level rise over the past 20 000 years

evaluation of the viscous behaviour of clay using generalised overstress viscoplastic theory in this paper generalised elastic viscoplastic evp theory combined with a power law is used to derive simplified equations relating undrained shear strength and preconsolidation pressure to strain rate an additional equation is derived relating the strain rate parameter in evp theory to the secondary compression index the derived equations are used to evaluate the rate sensitive and drained creep response of 20 clays reported in the literature the evaluation shows strong evidence that the rate sensitivity and time dependency of clay in compression can be described simultaneously using the generalised evp theory and power law in addition the constitutive parameter governing rate sensitivity in evp theory appears to be unique for constant rate of strain tests such as undrained triaxial compression and drained oedometer compression as well as stress controlled tests such as drained oedometer creep to conclude an approach to select the viscous parameters for clay is provided

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

traffic load induced permanent deformation of road on soft subsoil a method for predicting the traffic load induced settlement of road on soft subsoil with a low embankment is proposed the traffic load induced dynamic stress in subsoil is calculated by the multilayer elastic theory not covered in this paper then the plastic vertical strain in subsoil is calculated by an empirical equation in which constants are related to the physical and mechanical properties of subsoil the method was applied to analyze three different cases in saga japan comparisons of the calculated values with field data indicate that the proposed method can provide a reasonable prediction of traffic load induced permanent settlement of the road on soft subsoil with a low embankment the method is useful for designing the road with a low embankment on soft subsoil for the cases studied with embankment thickness of 0 75 to 2 7 m the depth significantly influenced by traffic load is about 6 m below the base of the embankments

one way cyclic triaxial behavior of saturated clay comparison between constant and variable confining pressure abstractthe one way cyclic triaxial test has been recognized as a useful tool for solving many engineering problems such as the prediction of deformation in subsoils under traffic loading most studies of the one way cyclic behavior of soils are performed in triaxial tests with constant confining pressure ccp which can apply cyclic compressive deviatoric stress only however the real stress field in subsoils under traffic loading includes varying normal stresses in three directions therefore it is more desirable to simulate the in situ loading conditions induced by passing vehicles through a combination of the varying deviatoric stress and varying confining pressure recognizing this two series of one way cyclic triaxial tests on remolded saturated clay were conducted in this study one in undrained conditions and the other in partially drained conditions in each series both tests with the ccp and variable confining pressure vcp were carried out comparisons between the results of the vcp and

characteristics of groundwater seepage with cut off wall in gravel aquifer i field observations1 this paper presents a case history of the leakage behavior during dewatering tests in the gravel strata of an excavation pit of a metro station in hangzhou china the groundwater system at the tes

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

interpretation of increased deformation rate in aquifer iv due to groundwater pumping in shanghai shanghai is a typical example of a region in china suffering from severe land subsidence previous investigations have shown that land subsidence is strongly related to groundwater pumping in both the temporal and spatial domains a series of field investigations shows that the deformation rate of aquifer iv aqiv has increased contributing significantly to the total subsidence in shanghai to predict the deformation behavior of aqiv in shanghai due to groundwater pumping four different models have been applied in this study i a model based on groundwater flow theory ii an elastic model based on cauchy mechanics iii a creep model incorporated into cauchy mechanics and iv a recently proposed land subsidence model by budhu based on cosserat mechanics based on a number of assumptions budhu s concept was extended to consider the time dependent behavior of groundwater potential in aquifers and the consolidation behavior of overburdened aquitards the calculated results of aqiv s deformation we

model tests on flow slide of lunar regolith simulant a significant fraction of lunar exploration is concerned with the lunar regolith over the last three decades theoretical and experimental effort has been directed towards investigating the mechanical parameters and chemical composition of lunar regolith however the properties of lunar regolith flow have received only limited attention even though there have been reports of lunar avalanches in this paper the flow evolution of a lunar regolith simulant at various inclined angles was investigated in a rectangular shaped flume constructed of plexiglas the objective of this paper is to study the flow patterns of lunar regolith simulant by using a fast shutter speed 1 140 s ccd camera 640 480 pixels configurations of the flow under the action of different chute angles are captured in addition the engineering strains of the different chute angles are also calculated the research results help to investigate the real lunar regolith flow slide to some extent

conceptual data model and method of settlement calculation for deformation and water release from saturated soft soil research on the seepage deformation of saturated soft soil has resulted in many achievements based mainly on existing seepage deformation control equations in reality however these control equations and related parameters suffer from many problems the conductivity coefficient in the seepage control equation and the consolidation coefficient in the consolidation equation clearly resemble each other in form however in existing regulations and practice soil deformation is rarely calculated by substituting the conductivity coefficient obtained from field hydrogeological experiments for the consolidation coefficient similarly seepage is seldom calculated by substituting the conductivity coefficient with the consolidation coefficient obtained from consolidation experiments this can be attributed to the fact that the two coefficients have some obvious differences moreover the settlement deformation of soil calculated using the existing seepage and consolidation models does not agree very well with the measured deformation also the values calculated using different models usually deviate markedly research indicates that these problems derive from the fact that the seepage and consolidation equations are based on different concepts of elementary volume this study proposes using two separate elementary volume concepts deformation elementary volume and control elementary volume the concepts are adopted for saturated soft soil and the results used to analyze the relationships and differences between the two concepts moreover we developed a conceptual data model cdm for the water released from and the deformation of the saturated soil the model discloses the differences between the consolidation and conductivity coefficients both in their physical significances and magnitudes the inter relationship between the two coefficients is also revealed an analytical solution for the deformation and water released from saturated soft soil is deduced based on the cdm model and the relationship between the hydrogeological and consolidation deformation parameters is established a physical test model for saturated soft soil under certain conditions is also designed to verify the analytical solution using a method of curve fitting seepage and deformation tests and case studies show that the parameters calculated using the consolidation model are in agreement with those obtained from the cdm seepage model based on the measured data for flux and settlement vs time furthermore the relationship between conductivity and consolidation coefficients is verified the method suggested in this paper is generally applicable to problems involving the consolidation coefficient volume compressibility conductivity coefficient hydraulic conductivity and specific storage of saturated soft soil etc thus its potential applications are numerous

cathodoluminescence in diagenetic calcites the roles of fe and mn as deduced from electron probe and spectrophotometric measurements quantitative spectrophotometric measurements of cathodoluminescence cl intensities of calcite cements from the mississippian lake valley formation are compared with mn and fe electron microprobe analyses of the same calcites cl intensities of these calcites show excellent positive correlation with mn concentrations at approximately constant fe mn ratio and within narrow ranges of fe contents r 0 76 to 0 97 our data suggest that fe mn ratios may control the maximum cl intensity of calcite below this maximum at constant fe mn ratios cl intensity can vary significantly and is controlled mainly by absolute concentrations of mn and fe cl intensities are therefore a function both of absolute concentrations of mn and fe and of fe mn ratios the data further suggest that cl intensities in calcites with low fe concentrations 1 000 ppm are more sensitive to mn activation than to fe quenching cl spectra on the calcites show no evidence of rare earth element activators visual estimates of cl intensities of these calcite cements compare moderately well with intensities measured with the spectrophotometer spectrophotometrically measured cl intensities of calcites in any single visually estimated category bright moderate dull non luminescent overlap with those from adjacent categories thus spectrophotometric measurements are distinctly superior to the visual estimates our data indicate that calcites with more than about 100 ppm mn will luminesce even in the presence of moderate amounts of fe in the absence of detectable fe calcites with about 150 to 650 ppm mn have moderate cl and those with mn contents greater than about 700 ppm have bright cl in the presence of detectable fe the amount of mn required to impart moderate or bright cl increases with fe content furthermore fe does not extinguish mn activated cl up to about 10 000 ppm fe the maximum of our data these results are in general agreement with the electron microprobe study of grover and read 1983 in partial agreement with the data of frank et al 1982 and in poor agreement with the data of fairchild 1983 considering the poor precision of the electron probe at low element concentrations 100 ppm our data are reasonably consistent with the published ion microprobe and atomic absorption data mason 1987 ten have and heijnen 1985 richter and zinkernagel 1981 which imply that mn concentrations in the 30 to 50 ppm range are sufficient to activate cathodoluminescence in calcites

an improved elastic viscoplastic soil model this paper develops an improved and accessible framework for modelling time dependent behaviour of soils using the concepts of elasticity and viscoplasticity the mathematical description of viscop

environmental protection using dewatering technology in a deep confined aquifer beneath a shallow aquifer abstract this paper presents an innovative technology referred to as dual function well dfw which has been developed in order to reduce the construction costs of dewatering when excavation is conducted in an aquitard over a confined aquifer dfw technology is a method to lower both shallow groundwater and deep groundwater either separately or simultaneously using one well the dfw includes two or more independent screens corresponding to each aquifer and a valve is located between the screens inside a steel pipe when the valve is closed groundwater is pumped from the upper screen in the shallow aquifer when the valve is open groundwater is pumped from the screens in both the shallow and deep aquifers dfw technology is used to replace the traditional method involving two sets of wells in which the first set of wells pumps groundwater from the shallow aquifer and a second set pumps groundwater from the deep aquifer to investigate the effectiveness of dfw field pumping tests using a dfw were conducted and both groundwater head and settlement were monitored numerical simulation was adopted to simulate the results of the pumping tests comparison between the results from the dfw and from an ordinary mixing well indicates that the use of a dfw with the valve closed can reduce the pumping time from a deep aquifer and can reduce the ground settlement caused by dewatering the results indicate the dfw technology is feasible and effective

quantitative paleoenvironmental and paleoclimatic reconstruction using paleosols abstract paleosols fossil soils are preserved throughout the geologic record in depositional settings ranging from alluvial systems to between basalt flows until recently paleosols were studied using primarily qualitative methods in recent years paleopedology has shifted from a largely qualitative field based on comparisons with modern analogues to an increasingly quantitative endeavor some of this change has been a result of applying existing techniques to new materials but many of the innovations have been the result of applying new techniques to new materials including thermodynamic modeling of soil formation isotope geochemistry and applications of empirical relationships derived from modern soils a variety of semi quantitative and quantitative tools has been developed to examine past weathering and pedogenesis and to reconstruct both paleoenvironmental and paleoclimatic conditions at the time that the paleosols formed though it is often not possible to achieve the same temporal resolution as with marine records for paleoclimatic reconstructions proxies based on paleosols are potentially a much more direct means of making paleoclimatic reconstructions because soils form at the earth s surface in direct contact with the atmospheric and climatic conditions at the time of their formation paleoclimatic and environmental properties that may be reconstructed using the new proxies include provenance weathering intensity mean annual precipitation and temperature during pedogenesis nutrient fluxes into and out of the paleosols the atmospheric composition of important gases including co2 and o2 the moisture balance during pedogenesis the soil gas composition reconstructed vegetative covering and paleo altitude

18o 16o and d h in goethite from a north american oxisol of the early eocene climatic optimum abstract an early eocene oxisol in the ione formation of california formed in a coastal continental weathering environment at a paleolatitude of 38 n the dominant minerals in the oxisol are goethite quartz and kaolinite material balance calculations were applied to new measurements of chemical composition d h and 18 o 16 o ratios of oxisol samples to determine the d 150 3 and 18 o 2 4 0 3 values of the goethite feooh these data in combination with the global meteoric water line mwl yielded an isotopic temperature of 21 4 c the nominal value of 21 c contrasts with the modern mean annual temperature mat of 16 c in that area the warmer temperature is consistent with formation of the goethite during the early eocene climatic optimum the isotopic composition of the goethite and a temperature of 21 c imply ancient water with a d value of 61 4 and a 18 o value of 8 9 0 5 this early eocene 18 o or d value is more negative than values in the range of isotopic scatter observed for modern global precipitation at sites with a mat of 21 c at times of warm global climates the location of a near surface atmospheric isotherm would generally shift relative to its location under modern climatic conditions a simple rayleigh type condensation model indicates that if one follows the isotherm the associated scatter in d and 18 o of precipitation in very warm global climates should shift for a given isotherm to more negative values that may be detectable in proxy records the isotopic results from the goethite of the early eocene oxisol appear to add to evidence in support of this idea

surface subsidence and drawdown of the water table due to pumping a fully coupled numerical method is presented for the analysis of the pumping of groundwater taking into account the drawdown of the water table the surface subsidence due to pumping is first studied assuming that the water table is not lowered as the groundwater is withdrawn this solution is then compared with the solution for the case in which the drawdown of the water table is considered extensive parametric studies were carried out to provide non dimensionalized design charts for surface subsidence and drawdown of the water table due to pumping l article presente une methode numerique permettant d analyser le pompage des eaux souterraines en prenant en compte le rabattement de la surface libre de la nappe la subsidence en surface du sol due au pompage est etudiee en supposant que la surface piezometrique ne baisse pas au fur et a mesure que l eau est pompee cette solution est ensuite comparee a la solution obtenue avec un rabattement de la surface piezometrique des etudes parametriques exten

stress strain response of soft clay to traffic loading approximately 25 of china s 120 000 km of expressway as well as many new metro lines and airports rest on soft clay deposits however service settlements are proving larger than expected especially in southeast china this note describes laboratory experiments on k0 consolidated intact samples of soft clay taken near wenzhou south east china that explore whether cyclic traffic wheel loading contributes significantly to the observed settlement trends cyclic triaxial ct tests are reported together with cyclic hollow cylinder chca experiments that imposed cardioid shaped 2 z z stress paths cyclic principal stress axis rotation is shown to have an important influence on vertical straining once a certain threshold has been exceeded the resilient and permanent strains developed in the chca tests become progressively larger than their counterparts in ct tests conducted at the same vertical cyclic stress ratio with trends that diverge progressively as vertical cyclic stress ratio incr

the destruction of paleoclimatic isotopic signals in pleistocene carbonate soil nodules of western australia stable carbon and oxygen isotopic analyses were conducted on small 10 mm spherical pleistocene carbonate soil nodules from 53 different levels in a 9 15 m soil auger collected in northern western australia the 13c and 18o values range from 4 to 0 and 9 to 6 pee dee belemnite standard respectively comparison of these values to the 13c values of coexisting soil organic matter som reveals marked differences between the two records the som values record an enrichment of 16 through the section whereas the carbonate values record only a 4 variability application of a diffusion production model to the data indicates isotopic disequilibrium between the two carbon records one possible interpretation of the apparent isotopic disequilibrium is that the nodules formed at depths of 1 cm but this interpretation is not supported by field observations an alternative is that the soil organic matter currently in the profile was emplaced after nodule formation such a scenario would have to have occurred numerous times during the late pleistocene as the nodules grew below different soil zones through time a third explanation is that diagenetic alteration of the carbonates in the presence of dissolved inorganic groundwater carbon has occurred this interpretation is consistent with the widely fluctuating regional groundwater table it is also supported by petrographic fabrics and heterogeneous cathodoluminescence patterns indicative of initial pedogenic development of the nodules and then at least one dissolution event multiple precipitation events prolonged nodule growth by displacive spars and microspars cementation and recrystallization of some micrite the results illustrate potential problems for 1 the use of some pedogenic carbonate isotopic records as proxies for environmental change and 2 the use of altered 18o values and unaltered 13c values as screening tools for the presence or absence of diagenesis the results highlight the necessity of understanding regional environmental conditions and diagenetic histories prior to using pedogenic carbonates in paleoreconstructions

evaluation of the predictive ability of two elastic viscoplastic constitutive models two elastic viscoplastic constitutive formulations are evaluated using laboratory and field data from sackville new brunswick and gloucester ontario both constitutive models have been implemented in a finite element program and formulated for undrained analysis and fully coupled analysis based on biot consolidation theory a laboratory study of the rate sensitive behaviour of sackville clay is described the response of sackville clay during consolidated anisotropic undrained cau triaxial creep cau triaxial compression and incremental oedometer consolidation is compared with the calculated behaviour the comparisons demonstrate the general ability of three parameter elastic viscoplastic constitutive models to satisfactorily describe the rate dependent behaviour of sackville clay the measured response of gloucester clay during long term rowe cell consolidation tests is compared with the calculated behaviour and the predictive ability of both constitutive formulations is evaluated using the field p

use and misuse of the isotache concept with respect to creep hypotheses a and b time dependent settlements of thick in situ clay layers are normally analysed based on results of thin laboratory specimens however the time used to complete primary consolidation is significantly different for laboratory specimens and in situ soil layers two totally different cases referred to as creep hypotheses a and b have been used as a basis of discussion to assess the effect of creep during the primary consolidation phase several laboratory and field experiments have been conducted to study the effect of soil layer thickness on the time dependent compressibility of a soil layer some of these tests seemed to support hypothesis a others hypothesis b and in some cases showed a behaviour between the two as a result this question has continued to be a controversial topic among researchers and remains to be an issue that needs to be resolved in this study some relevant experimental investigations from the literature are thoroughly studied and critically reviewed and also explained consistently using the isotache concept this work indicates that the isotache approach can capture the main characteristics of the time dependent compressibility of clays during both the primary and secondary consolidation phases it is also shown that the misuse of the isotache concept as reported in the literature may give a confusing picture of reality based on the considered data it is demonstrated that the measured time dependent compressibility of clays agrees well with hypothesis b

geology mineralogy and geochemistry of late miocene paleosol and calcrete in the western part of the central anatolian volcanic province cavp turkey abstract the late miocene was characterized by high global temperatures and partly to nearly complete desiccation of the mediterranean sea throughout the latter part of the messinian age the messinian salinity crisis the non marine paleoenvironmental and paleoclimatic records from the mediterranean area are highly limited in their spatial range late miocene river flood plain sediments in the central anatolian volcanic province cavp of central turkey consist of siliciclastic and pyroclastic sediments with paleosols and calcrete five lithofacies were identified as a massive conglomerate b trough cross bedded sandstone c massive mudstone d disrupted mud e and disrupted matrix supported conglomerate the paleosols were composed predominantly of smectite and illite with smaller amounts of feldspar quartz opal a pyroxene and amphibole and the calcretes were composed mainly of calcite with smaller amounts of feldspar quartz and opal a and minor amounts of smectite chlorite and illite authigenic clay minerals and micritic calcite coating on the detrital grains and soil peds and pendant cement in the calcrete and paleosol horizons were evidence of a vadose zone in contrast the large equant spar drusy mosaics were formed in phreatic environments the weathering of ignimbrite and marble led to the depletion of sio2 cao al2o3 fe2o3 tio2 and k2o through the precipitation of smectite and illite in the paleosols and cao in the form of micrite and calcite in the calcrete horizons field observations mineralogy geochemistry and the results of 18o and 13c isotopic analysis reveal that alternating wet and dry periods resulted in an upward increase in precipitation of authigenic smectite and illite within the late miocene sections under the influence of geochemical and ph fluctuations in phreatic or vadose water within the river flood plain paleoenvironment

characteristics of groundwater seepage with cut off wall in gravel aquifer ii numerical analysis this paper presents a numerical investigation into the leakage behavior of cut off walls in gravel strata due to dewatering in a deep excavation pit the calculated values of the groundwater head and surface settlement using a model agree well with the measured values values of the hydraulic conductivity k and storage coefficient ss of each soil layer are obtained from the test results when the cut off wall is 43 m deep the leakage through the cut off wall in gravel is analyzed by considering a variation in hydraulic conductivity in different sections of the cut off wall the simulated results show that a significant leakage occurred in the 54 m deep cut off wall although leakage did occur in the full cut off wall in the confined aquifer the full cut off wall is still more efficient in preventing groundwater seepage than the partial cut off wall the relative depths of the cut off wall and of the wells have a significant effect on ground surface settlement during the withdrawal of groundwater the

test on cyclic creep behavior of mucky clay in shanghai under step cyclic loading based on the cyclic triaxial test under step loading the variation of cyclic creep and pore water pressure with increase in cyclic stress ratio csr and load cycle of mucky clay in shanghai were analyzed the results show that there are two threshold values of stability cyclic stress ratio and failure cyclic stress ratio during the step loading which divide the development of cyclic creep strain into gradual stability stage rapid growth stage and instantaneous failure stage when the stress level is less than the failure cyclic stress ratio the recoverable elastic strain is nearly linear with csr the cyclic creep properties of mucky clay are obviously influenced by the loading frequency under the same stress level

measured and predicted time dependent stress strain behaviour of hong kong marine deposits hong kong marine deposits hkmd are considered to be difficult or weak soils for civil projects because of low shear strength and time dependent high compressibility understanding and modelling the time dependent stress strain behaviour of hkmd are of practical significance in the analysis and design of civil structures on and in hkmd in this technical note test data on the time dependent behaviour of a remoulded hkmd are presented and analysed an existing elastic viscoplastic evp modelling framework is used to describe the time dependent stress strain behaviour of hkmd the modelling results are compared with the measured results key words stress strain time dependent creep viscoplastic triaxial soil

in situ estimation of the coefficient of consolidation in clays an investigation was conducted to demonstrate the applicability of cylindrical piezocone and flat piezoblade tests for providing reliable estimates of the coefficient of consolidation in clays coefficients of consolidation were calculated from piezocone dissipation tests for different degrees of consolidation using theoretical time factors to provide a comparison with laboratory oedometer tests three techniques were developed to calculate the coefficient of consolidation from piezoblade dissipation tests results from in situ pore pressure dissipation tests were compared with laboratory oedometer tests performed on undisturbed samples oriented in both the vertical and horizontal directions to provide reference values of cv and ch the results of investigations conducted at several clay sites are presented key words in situ tests piezocone piezoblade coefficient of consolidation oedometer test clays

terrestrial evidence for a two stage mid paleocene biotic event abstract marine records of the paleocene indicate a series of hyperthermal events characterized by significant climatic and carbon cycle variability but there are few comparable continental records the mid paleocene biotic event mpbe is a recently described interval defined by a rapid negative carbon isotope excursion and major short term changes in marine ecosystems but it is as yet unclear whether the event was globally important here we present the first terrestrial paleoenvironmental record of the mpbe based on paleosols that document rapid and short lived increases in temperature and precipitation and resultant shifts in plant assemblages concomitant with substantial carbon isotope excursions the new record indicates that carbon cycle changes during the early late paleocene may have resulted in a two stage transient hyperthermal event that caused a significant perturbation to both the regional climate and terrestrial ecology of south america in addition to the major biotic event mpbe previously recognized in marine records overall this suggests that the mpbe may have been a global climate event with far reaching environmental impacts in both the marine and terrestrial realms

sensitivity of climate to late cenozoic uplift in southern asia and the american west numerical experiments experiments with general circulation models with no mountains half mountains and full modern mountains show the sensitivity of atmospheric circulation patterns to progressive amounts of uplift the experiments were motivated by geologic evidence for large kilometer scale uplift in the late cenozoic in southern asia and the american west particularly within the last 10 m y in january the amplitude of the mid latitude upper tropospheric planetary waves increased with uplift and the low level winds were progressively blocked or diverted around the topographic features in july the progressive uplift caused monsoonlike circulations to develop in the vicinity of the colorado and tibetan plateaus atmospheric heating rates midtroposphere vertical motion and upper tropospheric planetary wave amplitudes varied approximately linearly with progressive uplift these results suggest that geologically recent kilometer scale uplift may have had climatic consequences comparable in magnitude and pattern to those of earlier stages of uplift comparison of the simulated climatic effects of uplift with the geologic evidence for late cenozoic climatic change especially for the last 10 m y is given in accompanying papers

long term settlement of soft subsoil clay under rectangular or semi sinusoidal repeated loading of low amplitude by applying yin and graham s one dimensional 1 d equivalent time rheological model which can predict both primary and secondary settlement the expressions for calculating the long term subsoil settlement under rectangular or semi sinusoidal repeated loading of low amplitude are obtained without considering the fluid solid coupling a property has been proven that ultimate settlement of clay is independent of stress increasing history under 1 d conditions according to this property the expressions are derived considering the solid fluid coupling to approximately calculate the long term total settlement and the long term settlement of soft subsoil clay after construction of the road embankment because the expressions of the long term settlement are analytical solutions in the present paper they can not only avoid cumulative calculation errors in the numerical analysis but also have more solid theoretical foundations than empirical equations

time dependent behaviour of the bearpaw shale in oedometric loading and unloading time dependent behaviour can have a significant influence on the compressibility characteristics of soils however most of the research on this topic has investigated the behaviour of soft soils in this paper the time dependent behaviour of a hard clay shale bearpaw shale is investigated using both one dimensional multi staged loading msl oedometer and constant rate of strain crs oedometer consolidation tests conducted on 25 0 and 16 9 mm diameter specimens the results show that soft clays and hard clay shales that share the same c e cc ratio where c e is the secondary compression index and cc is the incremental compression index will show the same approximately 7 change in pre consolidation pressure for an increase of one log cycle of strain rate despite the many orders of magnitude difference in pre consolidation pressure in the case of the bearpaw shale this 7 change in pre consolidation pressure corresponds to approximately 700 kpa the time dependent behaviour of the bearpaw shale d

distinguishing climate in the soil record using chemical trends in a vertisol climosequence from the texas coast prairie and application to interpreting paleozoic paleosols in the appalachian basin u s a a suite of vertisols clay rich soils with high shrink swell potential were examined across a climosequence climatic transect in twelve soil pits from the coast prairie of texas in order to determine if mean annual precipitation map exerts a control on the chemistry of these soils and if the observed chemical trends are useful for interpreting paleoclimate records of paleovertisols in the geologic record the precipitation regime of the climosequence spans a range between 144 and 86 cm year with moisture regimes classified as udic udic ustic ustic and aridic ustic in a general northeast to southwest direction other soil forming factors such as soil age 35 40 ka parent material fluviodeltaic beaumont formation of late pleistocene age landscape low relief coastal plain and vegetation prairie or mixed woody shrubs are relatively constant across the climosequence climate sensitive chemical proxies of map identified include dithionite citrate extractable fe fedith acid oxalate extractable fe feoxal caco3 equivalent caco3equiv s and ammonium acetate extractable na k and mg naacet kacet and mgacet respectively which vary across the climosequence because of differences in effective depths of leaching and intensity of wetting and drying cycles these standard usda wet chemical climate proxies are related to bulk oxide or element chemistry of soils and paleosols measured using xrf which supports the use of geochemical climate proxies for interpreting the paleoclimate records of paleovertisols application of the chemical index of alteration minus potash cia k geochemical climofunction to late mississippian paleosols from the appalachian basin of the eastern u s demonstrates evidence for a shift from a lower to a higher map paleoclimate that is consistent with previous paleoclimate models and with observed morphological changes in the paleosols we advocate actualistic research using bulk chemistry of soils and paleosols as a means of obtaining soil information useful for interpreting paleosols in the geological record

sedimentologic and isotopic constraints on the paleogene paleogeography and paleotopography of the southern sierra nevada california detrital zircon u pb provenance and stable isotopic studies of three paleogene southern sierra nevada california basins place new constraints on the paleoelevation history of the region age spectra from the paleocene witnet formation within the southernmost sierra nevada link these sediments to source terranes that were at or near sea level in the early cenozoic while age spectra from the paleocene goler formation east of the sierra nevada demonstrate isolation of southern sierra nevada basins from the continental interior and tapping of jurassic and triassic arc flank sources during the paleocene west of the sierra nevada strata of the eocene tejon formation are dominated by cretaceous zircons sourced from the sierran batholith goler formation carbonate 18 o suggests paleocene paleoelevations of 1 2 km for the central and southern sierra nevada taken together these data indicate a paleogene southern sierra nevada with modest elevations locally dissected to sea level by rift basins formed by late cretaceous lithospheric collapse these results place new limits on the amount of regional middle to late cenozoic elevation gain that may have resulted from the loss of dense mantle lithosphere from below the central and southern sierra nevada and point to possible north south variations in the topographic evolution of the sierra nevada

postglacial rebound at the northern cascadia subduction zone postglacial rebound is the response of the earth to the decay of ice sheets a postglacial rebound model explains crustal tilting and rapid uplift at the northern cascadia subduction zone that occurred during retreat of the cordilleran ice sheet observations explained by the model include the shoreline tilts of two proglacial lakes that formed at 13 5 14 ka 14c yr ago and rapid sea level fall land uplift at 12 12 5 ka modelled mantle viscosity values range from 5 1018 to 5 1019 pa s and are consistent with previous viscosity inferences from observations of crustal deformation following subduction zone earthquakes 1018 1019 pa s no lower limit to subduction zone mantle viscosity is apparent from our model but viscosity values equal to or larger than 1020 pa s are de nitely ruled out our modelled subduction zone viscosity values are smaller than most upper mantle viscosity estimates derived from postglacial rebound studies of tectonically less active regions 1020 1021 pa s the rapid observed uplift at 12 ka requires in addition to a low mantle viscosity rapid unloading from a sudden collapse of remaining coastal portions of the southern cordilleran ice sheet the sudden collapse provides 0 18 m of global eustatic sea level rise approximately 0 7 of the sea level rise associated with melt water pulse ia predictions of a global postglacial rebound model ice 3g with a 1021 pa s upper mantle viscosity were previously applied to geodetic data from this region to isolate signals associated with the earthquake cycle owing to the low viscosity values and resulting rapid recovery of glacial deformation our model predicts present day postglacial rebound uplift rates at least 10 times smaller than ice 3g less than about 0 1 mm yr as the ice 3g adjustments were substantial this indicates the need for re evaluation of the geodetic data 2000 elsevier science ltd all rights reserved

paleosol geochemistry of the late paleocene goler formation of southern california abstract paleosol fossilized soil geochemistry can provide a record of paleoclimatic conditions due to the relationships between pedogenic processes and climate in this study paleosols from the late paleocene goler formation of southern california were used to determine the paleoclimatic conditions active during pedogenesis the enrichment and retention of soluble elements ca mg and na and the mobilization of fe and mn within the paleosol profiles suggest a climate with strongly seasonal precipitation similarly variations in the mn content and 13c ratio of pedogenic carbonate nodules also reflect seasonal precipitation regional paleotopography was likely an important control on the paleoclimate of the goler formation due to rain shadow effects although the size and location of these ancient mountains are poorly constrained the identification of climatic effects specifically associated with these variables provides new constraints

soil behaviour through field instrumentation an improved version of the observational method is developed and proposed the method uses field measurements as the direct inputs to the framework of the constitutive behaviour and analyses the be

ground truthing chemostratigraphic correlations in fluvial systems changes in elemental chemistry have been used to define stratigraphic correlations between wellbores in petroleum basins few publications however relate defined chemical stratigraphy to physical correlations and none have been found that do so in fluvial systems here chemostratigraphy is applied to permian fluvial sediments within the beaufort group of the karoo basin in south africa and a correlation between three logged sections is defined this correlation is tested against physically determined chronostratigraphic correlations achieved using heli lidar data to provide a high resolution correlation between two sections 7 km 4 4 mi apart and mapping of strata using google earth to produce a correlation between sections 25 5 km 15 8 mi apart the chemostratigraphic characterization that is defined using data from fine grained lithologies resulted in the recognition of eight chemostratigraphic packages with thicknesses between 50 and 250 m 164 and 820 ft over a stratigraphic interval of approximately 900 m 2953 ft two distinctive changes in geochemical composition of the coarser lithologies fluvial channel belts were seen over this interval in the two sections that are 7 km 4 4 mi apart higher resolution subdivision of chemostratigraphic packages was achieved to produce four correlative geochemical units 30 60 m 98 197 ft in thickness that provide a high resolution correlation the chemostratigraphic and chronostratigraphic correlations are in close agreement in both the 7 km 4 4 mi and the 25 5 km 15 8 mi spaced sections the thickness of the study interval and spacing of sections is analogous to published chemostratigraphy studies on subsurface sequences thereby ground truthing the use of chemostratigraphy for correlation in subsurface fluvial systems that are to some degree analogous to the beaufort group sediments of this paper

vacuum consolidation and its combination with embankment loading a method is proposed for determining the optimum penetration depth of prefabricated vertical drains pvds in cases where vacuum consolidation is combined with the use of pvds in a clayey deposit with two way drainage the advantages of combining vacuum pressure with embankment loading are discussed in terms of reducing preloading induced lateral displacement of the subsoil increasing the effective surcharge loading and reducing con struction time in the case of road construction a vacuum consolidation project conducted in saga japan is described and the results from a fully instrumented test section are presented and analyzed using a two dimensional finite ele ment approach the numerical simulations compare well with the field measurements the validated numerical ap proach is then used to examine the response of soft subsoil subjected to vacuum consolidation the results confirm the usefulness of the proposed method for determining the optimum penetration depth of pvds and the advantages of combining vacuum pressure with embankment loading

weathering sequence of soils from volcanic ash involving allophane and halloysite new zealand abstract the clay minerals in a series of soils from rhyolitic ash having the same stratigraphy but different leaching environments were estimated quantitatively by oxalate dissolution infrared spectroscopy differential thermal analysis electron microscopy and x ray diffraction three soils were studied in detail these were the kereone soil mean annual rainfall 1200 mm the ohaupo soil 1400 mm and the mairoa soil 2600 mm the kereone soil contained halloysite as the predominant clay mineral whereas the mairoa soil was mainly allophanic the ohaupo soil contained considerable amounts of both allophane and halloysite thus the allophane content of the soils increased as rainfall increased reflecting a sequence of increased l leaching the si concentration in soil solution decreased as rainfall increased also reflecting increasing leaching of the soils at mairoa si is rapidly removed and allophane al si 2 1 with monomeric silicate is formed whereas at kereone less leaching occurs si levels are higher and halloysite al si 1 1 with polymeric silicate is formed at intermediate sites either allophane or halloysite may form the often reported situation of younger allophanic beds overlying older 10 000 year halloysitic beds may not be due to allophane weathering to halloysite but may result from lower temperature and drier climate during the last glacial maximum between 10 000 and 26 000 years before present bp a new weathering scheme for volcanic ash in new zealand is presented

paleosols in clastic sedimentary rocks their geologic applications interest in pre quaternary paleosols has increased over the past decade in large part because they have proved to be beneficial in solving diverse geological problems the majority of paleosols are described from continental deposits most commonly from alluvial strata criteria for recognizing these paleosols have been extensively described however classifying them has proved more complicated pre quaternary paleosols are generally classified according to one or more modern soil classification systems although one new classification has been proposed exclusively for paleosols to avoid problems using the modern soil classifications in addition to taxonomic classification paleosols can be categorized according to the interplay among deposition erosion and the rate of pedogenesis when they formed paleosols can be solitary if they formed during a period of landscape stability following the development of an unconformity such paleosols are commonly thick and extremely well developed more commonly paleosols are vertically stacked or multistory because they formed in sedimentary systems undergoing net aggradation if erosion was insignificant and sedimentation was rapid and unsteady compound paleosols generally formed if the rate of pedogenesis exceeded the rate of deposition composite paleosols developed thick cumulative paleosols indicate that erosion was insignificant and that sedimentation was relatively steady both autogenic and allogenic processes can influence depositional and erosion patterns and thus affect the kinds of soils that form consequently paleosols can help to interpret the history of sediment deposition and the autogenic and allogenic processes that influenced a sedimentary basin paleosols are also helpful in stratigraphic studies including sequence stratigraphic analyses they are used for stratigraphic correlations at the local and basinal scale and some workers have calculated sediment accumulation rates based on the degree of paleosol development in addition to their stratigraphic applications paleosols can be used to interpret landscapes of the past by analyzing paleosol landscape associations at different spatial scales ranging from local to basin wide in scope at the local scale lateral changes in paleosol properties are largely the result of variations in grain size and topography at the scale of the sedimentary basin paleosols in different locations differ because of basinal variations in topography grain size climate and subsidence rate paleosols are used to reconstruct ancient climates even to estimate ancient mean annual precipitation map and mean annual temperature mat ancient climatic conditions can be interpreted from modern soil analogs or by identifying particular pedogenic properties that modern studies show to have climatic significance stable carbon and oxygen isotopes are also used to interpret ancient climate and some effort has been made to estimate mat from isotopic composition on the basis of

zircon an immobile index in soils interpretation of any element s mobility in soils needs rigorous means of calculating losses or gains in relation to parent rock the first mass balance calculations were based on isoelement changes major elements during conversion of fresh rocks to weathered materials harrisson 1933 leneuf 1959 isovolumetric mass balance calculations were applied for the first t ime in 1955 to determine mass transfers in saprolite millot and bonifas 1955 since that time numerous works have been carried out on mass balance calculations in determining transfers during weathering brimhall and dietrich 1986 recently equations used to calculate volumetric changes and net mass gain or loss of mobile elements have been based on zirconium mostly from the mineral zircon the aim of the paper is to question the axiomatic immobility of zircon in soils and then to assess the limit of mass balance calculations in surficial weathering systems

δ13c values of carbonate nodules across the permian triassic boundary in the karoo supergroup south africa reflect a stinking sulfurous swamp not atmospheric co2 abstract paleosol macromorphology petrography and stable isotope geochemistry of carbonate nodules from permo triassic p t boundary strata of the central karoo basin south africa are presented in order to evaluate their utility as geochemical archives of permian triassic paleoatmospheric chemistry and their potential to provide a terrestrial carbon isotope chemostratigraphy for correlation with contemporaneous global marine 13 c records paleosol morphologies across p t boundary strata of the central karoo basin indicate the region was a poorly drained seasonally to continuously flooded bottomland radiaxial calcite microspar and micrite microtextures are observed in the calcite nodules associated with p t paleosol profiles micritic calcite is typical of soil carbonate that forms in well drained soils characterized by open system gaseous diffusion between the soil and global atmosphere whereas more coarsely crystalline textures and radiaxial calcite are more typical of crystallization in phreatic environments with limited gaseous diffusion between the soil and global atmosphere in this regard only those nodules composed of micritic calcite can be considered as a potentially reliable source of proxy information for paleoatmospheric 13 c values across the p t boundary the 13 c values of all carbonate nodules from two overlapping measured sections near carlton heights south africa range from 24 4 to 1 8 whereas micritic calcite nodule 13 c values range from 7 0 to 21 3 comparison of calcite 13 c values with penecontemporaneous organic matter 13 c values indicate that calcite 13 c values 13 c values rather these more negative carbonate nodule 13 c values likely reflect calcite crystallization under poorly drained swampy conditions characterized by a semi closed chemical system that evolved independently of earth s troposphere therefore previously reported negative carbon isotope shift s measured from carbonate nodules in the karoo basin p t strata do not provide a record of atmospheric 13 c and probably do not provide a viable carbon isotope stratigraphy that can be realistically correlated with global p t marine carbon isotope stratigraphies