palaeohydrogeological insights from natural tracer profiles in aquitard porewater great artesian basin australia 1 the value of using environmental tracer profiles in aquitards to quantify fluid flux and to reveal information about palaeohydrology is largely unknown for parts of the world that were not glaciated during the cenozoic we present deep continuous vertical profiles of aquitard pore water chloride concentration and 2h 18o composition from the western margin of the great artesian basin australia where upward leakage is the dominant groundwater discharge mechanism at the deeper of the two sites studied the cl and 2h profiles exhibit a distinctive s shape which we interpret as a shift in the upper concentration boundary condition over time numerical simulations are used to support an hypothesis that the shallow phreatic aquifer was more saline and more enriched in 2h compared to current conditions prior to 120 ka followed by an extended freshening phase from 120 to 20 ka then a saline phase similar to current conditions for the last 20 ka these timeframes correspond favorably with results of previous studies into the palaeohydrology of nearby playa lake eyre at the shallower site the tracer profiles decrease exponentially with depth we explore several models for the evolution of these profiles and adopt one of long term salt input at ground surface at both sites tracer concentrations for groundwater sampled from the underlying artesian aquifer provide conclusive evidence that recharge occurred within the last 10 20 ka chloride was a more useful tracer than 2h in this study primarily due to lack of recent glaciation in central australia to provide a dynamic 2h tracer signal

field experiments in a fractured clay till 2 solute and colloid transport a field tracer experiment was conducted in a lateral flow field in the weathered and highly fractured upper 6 m of a 40 m thick clay rich till plain in southwestern ontario in the upper 3 m where fractures are closely spaced 5 m d simulations with a discrete fracture porous matrix flow and transport model which used the cubic law for flow in fractures showed that diffusion of the solutes but not the much larger colloids into the matrix pore water between fractures is sufficient to cause the observed difference in solute and colloid transport rates transport derived and hydraulic conductivity derived fracture aperture values were similar within a factor of 3 and falling mainly within a range of 5 40 m in the upper 3 m the solute tracers were evenly distributed between pore water in the fractures and the matrix and as a result solute transport can be closely approximated with an equivalent porous medium epm approach below this depth fractures are more widely spaced 0 13 to 1 m with concentration peaks tending to occur near visible fractures and solute transport cannot be adequately described with an epm approach

solute transport in formations of very low permeability profiles of stable isotope and dissolved noble gas contents of pore water in the opalinus clay mont terri switzerland pore water profiles of water stable isotope and dissolved noble gas content have been determined across the opalinus clay and adjacent formations at the rock laboratory at mont terri we have found enhanced helium contents up to 4he 1 10 4 cubic centimeters at standard pressure and temperature per gram of pore water and argon isotope ratios 40ar 36ar ratios up to 334 due to accumulation of 4he and 40ar produced in situ the helium profile was found to be in steady state with respect to in situ production and diffusive loss into the adjacent limestones where groundwater circulates from this profile a representative mean value of the apparent diffusion coefficient for helium in the pore water of the whole formation was derived for the first time to be da 3 5 10 11 m2 s 1 which is more than two orders of magnitude lower than the diffusion coefficient d0 in free water the stable isotope profile however indicates a component of fossil marine pore water which has not yet been replaced by molecular diffusion of meteoric water from the adjacent limestone and shale formations over the past 10 million years

impact of permeable conduits on solute transport in aquitards mathematical models and their application 1 the migration of contaminants through porous conduits for example sand layers in aquitards or any preferential flow feature within a low permeability matrix can be significantly retarded via diffusion into the matrix and processes such as sorption and decay previous solutions for simulating contaminant transport in these types of environments have been limited to a parallel plate approach such as that used in studies of fractured rock aquifers a major drawback of using these approaches is that they cannot account for the radial component of diffusion that occurs from circular or elliptical sectioned conduits we have developed solutions for both of the latter cases and compared results from generic simulations to those obtained with a conventional parallel plate model the results demonstrated using a circular conduit approach can produce concentration profiles for both the conduit and surrounding matrix that are up to several orders of magnitude lower than those predicted using parallel plate models the solutions for elliptical section conduits provide concentration profiles that are bounded by the circular and parallel plate models we also present several generic simulations to demonstrate the effects of conduit radius and average groundwater flow velocity on concentration profiles finally the circular conduit model is applied to a clay rich till aquitard in southern saskatchewan canada to provide insight into an anomalous dissolved chloride peak in the vertical pore water profile the model demonstrates that the source of the high cl could be as far as 10 100 km from the site although this distance may be unrealistic and allows estimation of the cl concentration at the source we envisage that the solutions for conduit diffusion will have far wider applications than just aquitard studies and future uses may include tracer tests in karstic and fractured aquifers

calabrian eopleistocene micromammal assemblages from the lacustrine and fluvial deposits of the southern trans urals and chronological position of some regional stratigraphic units abstract in the southern trans urals the quaternary deposits dated back to the early pleistocene 2 58 0 77 ma are scarce incomplete and often severely eroded data scarcity is a major challenge for accurate geological correlation and for integration of regional data into continent wide stratigraphic frameworks we provide a review of stratotypes and type localities for regional stratigraphic subdivisions of the eopleistocene the units correlated with the calabrian stage of the western european stratigraphical timescale 1 8 0 77 ma with particular focus on small mammals and their biochronological significance subdivisions of the eopleistocene which have been officially accepted in russia include three regional chronostratigraphic units horizons starting from uvel ka to chumlyak and sarykul we show that the calabrian deposits are characterized in the southern trans urals by sequential changes in the evolutionary level of micromammal assemblages that could be directly correlated with the mammal based biochronological zones mqr of russia vangengeim and tesakov 2008 tesakov and titov 2013 within the interval from mqr 10 to mqr 8 analysis of micromammal assemblages reveals incongruent positioning of the officially accepted uvel ka chumlyak and sarykul horizons in the regional stratigraphic chart the revealed incongruences appear to be a result of the difficulty to delineate chronostratigraphic units using the highly eroded and reworked sediments of fluvial origin the complete cycles of alternating fluvial lacustrine sedimentation and subaerial exposure provide the most reliable sections to establish the chronostratigraphic units of the calabrian stage of the early pleistocene in the southern trans urals the position of chumlyak and sarykul horizons in the regional stratigraphic chart of the southern trans urals is proposed to be changed the validity of the uvel ka formation as a chronostratigraphic unit should be further verified with a particular focus on faunal proxies mollusks ostracods and small mammals

81kr in the great artesian basin australia a new method for dating very old groundwater abstract the measurement of cosmogenic 81kr t1 2 2 29 0 11 105 yr has been proposed for many years as a reliable tool for groundwater dating in the range from 105 to 106 yr in this paper we report on the first use of 81kr to determine the age of groundwater from four wells in the great artesian basin in australia as the concentration of 81kr in old groundwater is only a few hundred atoms per liter krypton was extracted from large 16 000 l groundwater samples and was analyzed for the isotopic abundance of 81kr by accelerator mass spectrometry ams with a cyclotron 81kr kr isotope ratios of 1 54 0 22 10 13 1 78 0 26 10 13 2 19 0 28 10 13 and 2 63 0 32 10 13 respectively were measured for these samples it is reasonable to assume that krypton dissolved in surface water in contact with the atmosphere has the known atmospheric 81kr kr ratio of 5 20 0 40 10 13 the observed reduction of isotope ratios in the groundwater samples can then be interpreted as being due to radioactive decay since recharge this results in respective groundwater ages of 4 02 0 51 105 yr 3 54 0 50 105 yr 2 87 0 38 105 yr and 2 25 0 42 105 yr the main emphasis of this paper lies on the description of the analytic procedure to extract a reliable 81kr signal from large groundwater samples although the uncertainties are still relatively large primarily due to counting statistics caused by the low cyclotron ams efficiency the new technique enabled for the first time a definite determination of residence times for old groundwater with 81kr it thus confirms the hope that this radionuclide may become a very valuable tool for groundwater dating

comparing vertical profiles of natural tracers in the williston basin to estimate the onset of deep aquifer activation comparing high resolution depth profiles of different naturally occurring environmental tracers in aquitards should yield consistent and perhaps complementary information about solute transport mechanisms and the timing of major hydrogeological and climatological events this study evaluated whether deep continuous profiles of aquitard pore water chloride concentration could provide further insight into the paleohydrology of the williston basin canada than possible using high resolution depth profiles of stable h o isotopes of water 18o 2h pore water samples were obtained from extracts of cores taken over 392 m of the thick cretaceous shale aquitard water samples were also collected from wells installed in the underlying regional sandy aquifer mannville group 93 m thick and from seepage inflows into potash mine shafts to 825 m below ground numerical modeling of the 1 d vertical cl profile supported diffusion dominated solute transport in the shales the modeling also showed a similar time frame for development of the cl profile prior to activation of the aquifer as determined from the 18o profile 20 25 ma however it provided a significantly longer and potentially better constrained time frame for evolution of the profile during the activation phase of the aquifer 0 5 1 ma the dominant paleoevent reflected in present day profiles of both tracers is the introduction of glaciogenic meteoric water to the mannville aquifer underlying the shale during the pleistocene the source area of this water remains to be determined

understanding and modelling dissolved gas transport in the bedrock of three fennoscandian sites summary the origin and transport of dissolved gases in the geosphere is of interest for assessment studies of nuclear waste repositories in this paper we analyse available field measurements of helium methane and hydrogen at three fennoscandian sites forsmark and laxemar in sweden and olkiluoto in finland the field data are interpreted using different analytical models all based on the one dimensional diffusion equation the results of the different models provide estimates about the amount of deep gas flux the in situ production and the groundwater residence time of the considered sites the computed helium fluxes which fall within the lower range of crustal degassing fluxes reported by torgersen 2010 are strictly related with the high tightness of the considered fracture media the very high estimates of groundwater residence time indicate that at the considered depths there are only very few flowing fractures while in the rest of the fractured domain groundwater has been almost motionless during a whole glacial cycle

organic matter in senonian phosphorites from israel origin and diagenesis abstract the organic matter associated with senonian phosphorites from israel was studied and compared with that in tertiary phosphorites from morocco and modern phosphate rich sediments from south west africa namibia humic acids were found to be the main constituents of the organic matter in all samples the n alkane distribution pattern in the c15 c26 range and the lack of odd over even predominancy in the higher hydrocarbons indicate microbial degradation of marine derived organic matter significant phytane over pristane predominance indicates accumulation under euxinic conditions the high humic acid content and its relatively light 13c composition apparently reflect the two evolution stages suggested for the formation of phosphorites by g n baturin high decomposition rates of marine organic matter under limited oxygen supply led to the differential accumulation of more resistant fractions such as cellulose and lignin these compounds are known to be enriched in 12c relative to other marine organic compounds when exposed to oxidizing conditions during the second stage of non phosphate mud winnowing these compounds were easily converted into humic substances further conversion into kerogen was prevented due to shallow overburden and low maturation

field experiments in a fractured clay till 1 hydraulic conductivity and fracture aperture field values of horizontal hydraulic conductivity measured in the upper 1 5 5 5 m of a weathered and fractured clay rich till were strongly influenced by smearing around piezometer intakes which occurs during augering and by the physical scale of the measuring device values measured in conventional augered piezometers were typically 1 2 orders of magnitude lower than those measured in piezometers designed to reduce smearing measurements of hydraulic conductivity in small scale seepage collectors or piezometers which typically intersect fewer than 10 fractures vary over a much greater range 10 10 to 10 6 m s than large scale values based on infiltration into 5 5 m deep trenches which intersect thousands of fractures range 10 7 to 3 10 7 m s values of hydraulic fracture aperture 1 43 m and fracture porosity 3 10 5 to 2 10 3 were calculated using the cubic law with fracture orientation distribution measurements and the small scale hydraulic conductivity measurements this paper provides the first reliable determination of the magnitude and spatial distribution of hydraulically derived fracture parameters in a clay deposit the absence of such data has until now severely limited the application of quantitative groundwater flow and contaminant transport models in this type of deposit

effects of peat on the shapes of alluvial channels examples from the cumberland marshes saskatchewan canada abstract an avulsion of the lower saskatchewan river in the 1870s inundated a large segment of peat covered floodplain that subsequently has become aggraded with a broad 500 km 2 belt of alluvium deposited by the redirected flow routing of water and sediment discharge through the avulsion affected area has been accomplished mainly by networks of sandy bedded anastomosed channels that have formed evolved and abandoned as the alluvial belt prograded down the floodplain slope these processes continue today though at a much reduced rate new channels formed by crevassing and basinward extension of distributaries are initially small and shallow with bottom elevations situated within the avulsive alluvium but above the pre avulsion peat floodplain surface subsequent enlargement and downcutting of many of these channels eventually uncovers the underlying peat layer whose resistance to erosion exerts significant influence on cross sectional shape and further channel development peat floored channels tend to have rectangular cross sections high ratios of average to maximum depth d d max and a large range of width to depth ratios if the channel continues to enlarge the peat layer eventually becomes breached commonly leading to temporarily irregular cross sections caused by localized scouring at the breach sites eventually the peat layer is completely eroded from the channel floor by undercutting and slumping after which channel shape becomes governed mainly by other perimeter characteristics channels unaffected by peat either before the peat layer is encountered during early channel development or after it is entirely removed tend to have low width depth ratios and a large range of d d max values

influence of matrix diffusion and exchange reactions on radiocarbon ages in fissured carbonate aquifers the parallel fissure model coupled with the equation of diffusion into the matrix and with exchange reaction equations has been used to derive a simple formula for estimating the influence of matrix porosity and reaction parameters on the determination of radiocarbon ages in fissured carbonate rocks examples of evidently too great radiocarbon ages in carbonate formations which are not explainable by models for the initial sup 14 c corrections can easily be explained by this formula parameters obtained for a chalk formation from a known multitracer experiment combined with a pumping test suggest a possibility of sup 14 c ages more than three orders of magnitude greater than the ages which would be observed if the radiocarbon transport took place only in the mobile water in the fissures it is shown that contrary to the solute movement on a small scale and with a variable input the large scale movement characteristic for the sup 14 c dating does not necessarily require the knowledge of kinetic parameters because they may be replaced by the distribution coefficient discordant tritium and sup 14 c concentrations are commonly interpreted as a proof of mixing either in the aquifer or at the discharge site for fissured carbonate formations however anmore alternative explanation is given by the derived model showing a considerable delay of sup 14 c with respect to nonsorbable tracers less

sources of radiogenic helium in a clay till aquitard and its use to evaluate the timing of geologic events abstract concentrations of dissolved gases he ne ar and n 2 were measured in pore waters collected from a pleistocene 0 80 m depth and cretaceous 80 156 m depth aged clay rich aquitard system using both a conventional copper tube method and in situ diffusion samplers both methods yielded similar results he data revealed a well defined increase in concentration with depth from 1 7 10 8 cm 3 he stp g 1 water near the water table at 2 3 m below ground surface to 6 9 10 6 cm 3 he stp g 1 water at 80 m below ground surface b g the concentration at depth greatly exceeded values for atmospheric solubility at in situ temperatures and could not be attributed to steady state production from decay of u and th within the aquitard system trends in he isotope ratios and concentrations suggest accumulation as a result of both release of residual 4 he from within the pleistocene clay rich till ca 87 and an ascending radiogenic helium flux from underlying cretaceous age sediments ca 13 one dimensional transport modeling of the he data suggests that between 15 ka and 25 ka were required to produce the observed profile this time frame agrees with studies utilizing isotope tracers i e d h and 14 c dic to estimate the timing of deposition for the till at this site our results demonstrate the utility of using helium a nonreactive tracer for delineating hydrogeologic processes in slow permeability geologic strata and also support the contention that thick clay rich surficial aquitards can provide long term containment of contaminants including hazardous wastes

controls on the long term downward transport of δ h of water in a regionally extensive two layered aquitard system 1 seven high resolution 0 3 0 6 m depth intervals 1 d vertical profiles of the h of pore water were collected across a 300 km2 study area in southern saskatchewan canada to define the vertical controls on solute transport in a 120 m thick two layered aquitard system the 1 d profiles were augmented with an existing h profile collected from a previous study the surficial aquitard in the area consists of quaternary deposits either glacial till or lacustrine deposits 13 to 128 m thick underlain by an upper cretaceous claystone aquitard 80 110 m thick the shape of the individual h profiles and associated 1 d transport modeling suggest diffusion is the regionally dominant vertical transport mechanism across the aquitards the profile shape is controlled by the thickness of the quaternary deposit and the h value at the upper boundary which coincides with the depth of the water table the upper boundary h value varies considerably across the area 149 to 101 perhaps due to differences in local hydrological conditions e g slope aspect infiltration across the landscape modeling of all profiles shows the timing for till deposition and the timing of climate change during the holocene are consistent across the area 30 ka and 7 10 ka before the present respectively corroborating other studies this study provides insights into the hydrogeologic controls on solute transport in an aquitard system and associated geologic and climatic changes for a prairie region over the past 30 ka and improves our understanding of initial and time dependent transport boundary conditions for the study of aquitards

a comparison of groundwater dating with 81kr 36cl and 4he in four wells of the great artesian basin australia the isotopic ratios 81 kr kr and 36 cl cl and the 4 he concentrations measured in groundwater from four artesian wells in the western part of the great artesian basin gab in australia are discussed based on radioactive decay along a water flow path the 81 kr kr ratios are directly converted to groundwater residence times results are in a range of 225 400 kyr with error bars in the order of 15 primarily due to counting statistics in the cyclotron accelerator mass spectrometer measurement additional uncertainties from subsurface production and or exchange with stagnant porewaters in the confining shales appear to be of the same order of magnitude these 81 kr ages are then used to calibrate the 36 cl and the 4 he dating methods based on elemental analyses of rock samples from the sandstone aquifer as well as from the confining bulldog shale the in situ flux of thermal neutrons and the corresponding 3 he 4 he and 36 cl cl ratios are calculated from a comparison of i the 3 he 4 he ratios measured in the groundwater samples with the calculated in situ ratios in rocks and ii the measured n 37 cl ratios with the 4 he concentrations measured in groundwater it is concluded that both helium and chloride are most likely added to the aquifer from sources in the stagnant porewaters of the confining shale by diffusion and or mixing based on this working hypothesis the 36 cl transport equation in groundwater is solved taking into account i radioactive decay ii subsurface production in the sandstone aquifer with an in situ 36 cl cl ratio of 6u10 315 and iii addition of chloride from a source in the confining shale with a 36 cl cl ratio of 13u10 315 lacking better information it is assumed that the chloride concentration increased linearly with time from an unknown initial value ci to its

the isotopic composition of radiogenic helium and its use to study groundwater movement in confined aquifers abstract the 3 he 4 he ratio for radiogenic he is shown to be primarily determined by the abundance of li and neutron absorbing elements in the host formations and is almost independent of the radioelement abundance the 3 he 4 he ratios have been computed for various li contents in rock matrices with average abundances of other elements the 3 he 4 he ratio is specific for each formation and may therefore be used to study crustal diffusion of he it is shown however that both the 3he and 4he contents of continental basements are likely to exceed those of the mantle so that diffusion of mantle he through continental crust is not likely to occur changes in the 3 he 4 he ratio for dissolved he have potential for studying groundwater movement and mixing processes atmospheric he which was dissolved at recharge is progressively diluted by radiogenic he with an isotopic ratio characteristic of the aquifer as the groundwater migrates down dip mixing proportions for formation he and atmospheric he in aquifers for which there is admixture of fracture borne water and interstitially stored water can also be estimated from isotopic measurements these processes are discussed in relation to two aquifers in eastern england

spectroscopic and chromatographic studies of organic carbon in recent marine sediments from the peruvian upwelling zone abstract early diagenesis of organic matter in sediments from two sites in the peruvian upwelling zone 12 05 s 77 39 w 15 17 s 75 24 w has been studied by observing changes in the total organic carbon and lipid and humin fractions with depth transformations of the total carbon and humin fraction have been characterized by conventional and time dependent solid state nmr techniques while lipid diagenesis was monitored by measuring the concentration of sterols in the same sedimentary horizons both the quantity of total sterols and the relative abundances of individual sterols vary with sampling location suggesting a difference in the input of biomass to the sediments at the two sites total sterol concentrations decrease with depth at both sites but the loss of sterols occurs much more slowly at the more anoxic northern site where sedimentation rates and organic carbon contents are approximately twice those at the southern site 13 c nmr spectra of the total organic carbon and the humin fraction suggest that humin like compounds are an original component of the sedimentary biomass and dipolar dephased spectra of the humin residue indicate that diagenetic alterations of the humin fraction are occurring even in these very young sediments conventional and time dependent spectroscopic data support the hypothesis that humin formation results from selective preservation of microbially resistant biopolymers which are an original component of the sedimentary biomass combined with loss of certain labile compounds

stagnant aquifer concept part 1 large scale artesian systems great artesian basin australia artesian systems 1000 2000 m deep occurring in the one and half million km2 great artesian basin gab are described by most researchers as through flow aquifers that are recharged at eastern outcrops in the great dividing range a simplified mathematical model assuming basin wide through flow in two aquifers of jurassic and cretaceous rocks has been applied by previous researchers to calculate hydraulic travel times the latter were described as agreeing with groundwater ages of 105 to 106 years computed from 36cl data assuming part of the observed 36c1 was atmospheric and 4he ages assuming the bulk of observed 4he diffused from the crust an alternative conceptual model is discussed in this paper suggesting that artesian wells drilled into the deep jurassic rocks of the gab are tapping stagnant aquifers that are hydraulically isolated from each other the stagnant aquifers are envisaged as mega fluid inclusions formed during the subsidence of the basin the age of the water in the stagnant aquifers is expected to be high between the age of the host rocks connate water and the age of the subsidence stage at which the aquifer was sealed off by covering sediments and burial to beneath the active base of drainage isotopic ages were calculated to be in this range of very old groundwaters the chlorine 36 data were interpreted as being beyond the dating limit of this method i e over one million years suggesting that the bulk of the observed 36c1 was produced in situ and the 4he ages were computed to be 5 10 million years or more suggesting that all the he was produced in the aquifer rocks alone the groundwater in the artesian systems is concealed and hence the through flow and stagnant aquifer models are both based on interpretation of indirect observations mathematical modeling is not feasible either as too many parameters pertaining to the number of distinct aquifers their rock properties and other components of the groundwater cycle are unknown hence a phenomenological approach is adapted and the through flow and stagnant aquifer models are weighed up in the light of first principles of physics geology hydraulics chemistry and isotopic compositions

soilscape evolution of west tien shan during the late pleistocene based on humus properties of the obi rakhmat archaeological site analysis of the pedogenic humus properties of sediments at the obi rakhmat archaeological site is the basis for reconstructing soil forming processes as records of climatic fluctuations in the region of west tien shan the stratigraphic section has 10 zones of pedogenesis that are distinguishable by pedogenic humus and other features and consequently by the character of ancient soil forming processes we found that most of the sediments accumulated in an environment where serozem soils form that is in an arid subtropical landscape desert steppe zone the scheme of the altitudinal landscape sequence and the structure of the soil cover also changed according to climatic changes and regular displacements of the altitude zones occurred when analogs of modern dark serozems dominated near the site the altitude sequence was characterized by the most complexity with humid as well as arid landscapes occupying areas of the slopes climatic change trends both to humidity and to aridity simplified the altitude scheme when climate was arid humid landscapes were ousted mountain brown forest soils occurred only on the slope tops in contrast when climate was humid arid landscapes disappeared from the altitude sequence and forest and meadow zones were dominant

groundwater dating by estimation of groundwater flow velocity and dissolved 4he accumulation rate calibrated by 36cl in the great artesian basin australia abstract we tested two methods for dating groundwaters that cannot be reliably measured by 36cl dating alone one based on groundwater flow velocity plus distance along a flow path and the other based on 4he accumulation rates calibrated with 36cl dates we sampled groundwaters along six inferred regional groundwater flow paths in the great artesian basin gab of australia we selected three groundwater paths where the decrease in 36cl was largely controlled by cosmogenic 36cl radioactive decay without a significant increase in chloride concentration the extrapolated groundwater velocities were 0 133 0 018 m y to 0 433 0 140 m y the estimated residence time of 1 06 106 y at the discharge area around lake eyre was comparable to the estimate of 1 2 2 106 y in previous studies on the other hand our estimated 4he accumulation rates for the selected three groundwater flow paths 1 85 0 31 10 11 to 1 51 0 63 10 10 ccstp cm3 y were approximately 2 15 times lower than previously reported rates for the central gab our estimated rate of 1 51 10 10 ccstp cm3 y 1 in the western gab is compatible with previous estimates based on 81kr ages the groundwater residence time estimated from the 4he accumulation rate was approximately 7 105 y near the discharge area at lake eyre finally both estimations were mutually compatible with a 30 error

a magnetostratigraphic reassessment of correlation between chinese loess and marine oxygen isotope records over the last 1 1 ma abstract we present a magnetic polarity based paleoclimatic correlation between chinese loess and marine oxygen isotope stage mis records over the last 1 1 ma this revised land ocean comparison indicates that inconsistent occurrence of the matuyama brunhes boundary which lies in mis 19 in marine sediments and occurs either at the base lower part of loess l8 or the uppermost part of soil s8 in chinese loess is due to regional and or local climate variability across the chinese loess plateau and does not need to be attributed to lock in effects of loess remanence acquisition associated with pedogenesis this result implies that the geomagnetic polarity boundaries in chinese loess in general are reliable chronostratigraphic time markers therefore astronomically tuned timescales for chinese loess that presume a downward shift of polarity boundaries due to a time lag in remanence acquisition may have overestimated ages of certain loess paleosol units

humic substances in an arabian shelf sediment and the s1 sapropel from the eastern mediterranean abstract the molecular size distribution of humic substances has been investigated in sediment from two different geographical sites two depth horizons in a core sample taken from the arabian sea upwelling region age limits of 700 3000 yr have been analysed together with samples of the s 1 sapropel and the underlying grey marl deposit from the eastern mediterranean the extractable humic substances account for 20 of the total organic c in the sapropel 50 in the grey marl and 76 and 58 in the arabian sea sediments the humic compounds are described on the basis of their molecular weight distribution elemental composition and ir spectra results are considered in relation to the likely sources of organic c at each site the age of the sediment and the sedimentary environment the results obtained indicate that in both areas during the formation of the organic rich deposits the major source of organic c was planktonic the humic and fulvic acid distributions being dominated by high molecular weight humic acids

elevation adjustments of paired natural levees during flooding of the saskatchewan river natural levees control the exchange of water between an alluvial channel and its floodplain but little is known about the spatial distribution and evolution of levee heights the summer 2005 flood of the saskatchewan river cumberland marshes east central saskatchewan inundated large areas of floodplain for up to seven weeks forming prominent new deposits on natural levees along main stem channels measurements of flood deposit thickness and crest heights of 61 levee pairs show that the thickest deposits occur on the lower pre flood levee in 80 of the sites though no clear relationship exists between deposit thickness and magnitude of height difference only 16 of the pairs displayed thicker deposits on the higher levee half of which occurred at sites where relatively clear floodbasin waters re entered turbid channels during general flooding difference in crest elevation e between paired levees is approximately log normally distributed both before and after the flood though with different mean values supplemental observations from tank experiments indicate that during near bankfull flows temporally and spatially variable deposition and erosion occur on levees due to backwater effects associated with nearby channel bars and irregular rises of the channel bed forced by channel extension during floods preferential deposition in lows tends to even out crest heights copyright 2009 john wiley sons ltd

effects of peat compaction on delta evolution a review on processes responses measuring and modeling abstract peat is most compressible of all natural soils compaction of peat layers potentially leads to substantial amounts of land subsidence peat is common in many distal parts of holocene deltas which are often densely populated it is known that land subsidence due to peat compaction may have serious societal implications in such areas as it may cause damage to construction works and lead to land inundation effects of peat compaction on the natural evolution of deltas are however poorly understood whereas this might be an important control on delta evolution at both local and regional scales the main objective of this paper is to review current knowledge concerning the peat compaction process and its effect on delta evolution in holocene settings and to identify gaps in this knowledge an overview is given regarding 1 the compaction process 2 presumed and potential effects of peat compaction on delta evolution 3 field methods to quantify peat compaction and 4 numerical models to calculate the amount and rate of peat compaction peat compaction and formation influence channel belt elevation channel belt geometry and channel belt configuration last mentioned aspect mostly concerns the influence of peat compaction on avulsion which is one of the most important processes controlling delta evolution interactions between peat compaction peat formation and avulsion have seldom been studied and remain unclear partly because factors such as peat type organic matter content sediment sequence composition and groundwater table fluctuation are so far not taken into account peat compaction and formation potentially influence avulsion as 1 a decrease in accommodation space created by peat compaction underneath a channel causes superelevation and or an increase in lateral migration 2 the high cohesiveness of peat banks inhibits lateral migration which increases bed aggradation decreases sediment transport capacity and hence increases crevassing frequencies which possibly evolve into an avulsion although the low regional gradient in peatlands will hinder this and 3 peat compaction and oxidation in flood basins following groundwater table lowering leads to relief amplification of channel belts at delta scale variations in compaction rates might stimulate the occurrence of nodal avulsions to quantify effects of peat compaction on delta evolution and to determine the relative importance of different factors involved field research should be combined with numerical models describing peat compaction and formation the model should be validated and calibrated with field data

sarykul paleosol in southern urals sediments russia abstract sarykul paleosols in the southern urals russia with a stable position in geological sediments are considered the brunhes matuyama boundary was found in these paleosols and they were used as a source of information on the environment data were obtained during the study of the sarykul paleosols in four sections located in the mountain part of the southern urals on the miass river erosion accumulation terrace and at the eastern edge on the trans uralian peneplain saykul paleosols have a relatively thick and compact humic horizon with a tongued lower boundary the paleosols are dark grey with high toc content that is not usual for the early pleistocene paleosols the materials showed that sarykul paleosols formed on different parent rocks may have various characteristics of the mineral part texture ph magnetic susceptibility carbonate content ratio of exchangeable cations while their humic substances characteristics humic and fulvic acid ratio humic acid characteristics of elemental composition and structure are very similar climate conditions during sarykul paleosol formation changed from relatively warm and humid to less warm and more humid the study of southern urals sarykul paleosols has shown that they can serve as a reliable marker of the final early pleistocene due to their specific characteristics not analogous to the modern soils

the matuyama brunhes boundary in loess sections in the south of the east european plain and their correlation on the basis of palaeomagnetic and palaeopedologic data abstract the matuyama brunhes boundary mbb in loess sections of the east european plain one of the greatest areas of global loess distribution is a highly debatable issue the ambiguity of the mbb position here results from the complexity of loess soil magnetization processes and an apparent delay in loess remanence acquisition and from the uncertainties of pedostratigraphic interpretations in the don glaciation area the mbb is unanimously placed below the don moraine although the exact position is still controversial in the sites of the northern azov sea the mbb is however placed in the loess horizon considered to be the equivalent of the don moraine in the north the inconsistency of this interpretation is demonstrated by detailed magnetostratigraphic and pedostratigraphic studies in the western sites of zaporozh e dnieper basin novaya etuliya lower danube basin and roxolany lower dniester basin in all these sites albeit with certain minor discrepancies the mbb is found two or three interglacial palaeosols below the don loess which is overlain by the good stratigraphic marker of the vorona pedocomplex a thick polygenetic red brown palaeosol formed supposedly in a mediterranean climate here the mbb is placed in a quadruple soil unit termed roxolany loess soil suite which consists of four closely spaced strongly calcareous soils occupying an interval between the don loess on top and the earlier well developed bobrov loess with reversed matuyama magnetization the roxolany suite can possibly be correlated with the three palaeosols of the pre don ilyinka unit of the russian unified stratigraphic scheme and thus confirms the interpretation of the mbb in the central areas of the east european plain as to the interval between the ternovka second pre don palaeosol and the troitsk third pre don palaeosol

controls on the distribution of major ions in pore waters of a thick surficial aquitard transport and geochemical processes controlling the chemical and isotopic composition of pore waters in the upper 45 m of a thick surficial clay rich till battleford formation were studied the upper 3 m of the till is oxidized and fractured the remaining 77 m of the till the aquitard is nonfractured and unoxidized concentrations of total dissolved solids so42 na mg2 and k decrease with depth through the unoxidized zone to a depth of about 15 m below ground below which the concentrations remain constant a similar trend was observed for alkalinity however the decrease in concentration occurs over 20 m in contrast to these ions ca2 concentrations increase with depth through the upper 20 m unoxidized zone below which the concentrations remain relatively constant the distribution of dissolved ions shows the presence of two end members elevated solute concentrations in the oxidized zone attributed to geochemical weathering that occurred since the start of the holocene and connate pleistocene age water at depths between 20 and 45 m abiotic and biotic geochemical reaction rates in the aquitard were shown to be extremely slow or not occurring

pedohumic method in paleoenvironmental reconstructions abstract paleopedology can be an instrument to better understand problems in natural and humanitarian sciences a new pedohumic method involving diagnosis and reconstruction of paleoenvironments is suggested the reconstruction of the kazantsevo r w interglacial paleoenvironment in the chulymo yenisei depression middle siberia is considered as an example the trend of environmental conditions within the r w interglacial is similar to that of the current southern taiga steppe

matuyama brunhes boundary in key sections of the loess paleosol glacial formations on the east european plain abstract multidisciplinary studies of two key sections parastratotypes of the loess soil glacial formation strelitsa and sebryakovo mikhailovka sections located in the central part of the east european plain placed the matuyama brunhes reversal well below the lower pleistocene till the till attributed to the don glaciation maximum glaciation on the east european plain is separated from the m b reversal by several units as follows 1 a horizon of humified loam of still uncertain stratigraphic position 2 a loess horizon and 3 a paleosol complex rzhaksa the polarity reversal is within a transitional zone which includes the base of the lower bobrov loess and the upper portion of the underlying soil complex balashov the primary constituent of remanent magnetization has been identified using two methods demagnetization by heating and by alternating magnetic field such a technique ensures a high degree of reliability

roxolany and novaya etuliya key sections in the western black sea loess area magnetostratigraphy rock magnetism and paleopedology abstract loess paleosol sequences in the western black sea area at roxolany 48 m thick and novaya etuliya 30 m thick were studied using paleo and rock magnetic methods in conjunction with micromorphology and mossbauer investigations although seemingly complete the sites show variability in the type and number of loess paleosol cycles and inconsistency of the matuyama brunhes boundary mbb stratigraphic position at roxolany nine pedocomplexes pk and several incipient paleosols alternating with thick loesses were observed with the mbb being located between pk 6 and pk 7 at novaya etuliya 13 pks occur upon terrace xii with khapry fauna and with the mbb in the upper part of pk 7 and the jaramillo subchron within the lower part of pk 8 the depth functions of rock magnetic properties organic carbon content c org both for bulk samples and for clay extracts along with micromorphology and mossbauer spectra allowed objective identification of individual soils within pks and maximizing the resolution of paleopedological reconstructions of global climatic stages the mossbauer studies demonstrate that paleosols are basically enriched in ferric montmorillonite oxidized magnetite ultrafine iron hydroxides and hematite are intimately associated with clay minerals in contrast fe compounds in loess consist mainly of ferrous silicates these data indicate that the paleosol magnetism is basically of bio chemogenic origin and is related to pedogenic transformation of fe compounds in a changing environment while loess magnetism is primarily detrital pedogenic magnetically soft and partly oxidized magnetite may also originate during or even after burial this ensuing transformation of fe minerals in paleosols seems to be crucial for the understanding of the timing of natural remanent magnetization nrm in subaerial sediments given that paleosols formed on the similar parent material loess their typological variability seems to depend on climate and or chronology hence the different paleosol types from roxolany and novaya etuliya provide key information for intra and inter regional correlation of loess soil sequences and represent valid paleoclimatic proxies

helium release during shale deformation experimental validation this work describes initial experimental results of helium tracer release monitoring during deformation of shale naturally occurring radiogenic 4he is present in high concentration in most shales during rock deformation accumulated helium could be released as fractures are created and new transport pathways are created we present the results of an experimental study in which confined reservoir shale samples cored parallel and perpendicular to bedding which were initially saturated with helium to simulate reservoir conditions are subjected to triaxial compressive deformation during the deformation experiment differential stress axial and radial strains are systematically tracked release of helium is dynamically measured using a helium mass spectrometer leak detector helium released during deformation is observable at the laboratory scale and the release is tightly coupled to the shale deformation these first measurements of dynamic helium release from rocks undergoing deformation show that helium provides information on the evolution of microstructure as a function of changes in stress and strain this article is protected by copyright all rights reserved

carbon and sulfur relationships in marine senonian organic rich iron poor sediments from israel a case study abstract in fe poor and organic rich marine sediments reduced s is mainly organic due to the lack of reactive fe these sediments e g carbonates cherts phosphates have high c s organic carbon total reduced sulfur ratios which are as a rule 3 and may reach 5 or 6 at times even 10 in organic rich rocks these high ratios are characteristic for these fe barren sediments and are very different from those found in marine sediments where pyritic s is the main reduced sulfur species they may be explained by the escape of h 2 s to the atmosphere the interpretation of c 1bs plots in these sediments is also quite different one reason for the s intercept in these plots is the presence of pyritic s and thus contrary to the conventional plots this intercept seems to have no environmental significance on the other hand the s c slope appears to be a paleoenvironmental indicator low slopes 0 2 indicate restricted to normal aerobic environments c 1bs plots have been used to interpret environments of deposition in such sediments from two cycles of organic rich fe poor senonian sediments in several basins in central and southern israel both cycles appear to have been deposited in restricted environments the campanian mishash formation environments of deposition appear to be in general more oxic than those of the maastrichtian ghareb formation as an independent comparison for the c s results the degree of pyritization dop was calculated for some samples the dop results confirmed the c s results it should be stressed that in such low fe environments even dop results should be used with caution

natural levee deposition during the 2005 flood of the saskatchewan river abstract in summer 2005 a controlled flood of the saskatchewan river east central saskatchewan canada resulted in general floodplain inundation and extensive natural levee deposition along a 60 km reach extending from 40 km below the e b campbell dam to cumberland lake levee crests along channel banks were inundated for up to 7 weeks in some areas of the floodplain new deposits on levee crests varied from 0 to 70 cm in thickness displaying large variations both along reach and in opposing sites across channels mean grain sizes mainly silt and very fine sand likewise varied considerably among sample sites pre and post flood surveys of channel cross sections along the flooded reach permitted assessments of relationships between channel area changes and patterns of levee sedimentation in this system in which virtually all new flood sediment was derived by channel scour results show that both net deposition and net erosion occurred within the channel cross sections but that on average net channel enlargement of 4 2 prevailed over the entire survey reach when weighted by cross section size over the 60 km flooded reach zones of thick levee deposition occur at or just downstream of two areas of major channel enlargement and an intermediate zone of thin levee deposits is associated with an intermediate area of net channel aggradation this bimodal distribution of flood deposit thickness is inferred to have resulted from differences in sediment supply produced locally by the different extents of channel perimeter erosion two other factors 1 position of interfacial zones between clear floodbasin water and turbid channel water and 2 difference in pre flood levee heights contributed to the poor correspondence in thickness and grain size between opposing levees at some sites additional features of the new levee deposits including increases in transverse slopes abrupt basinward fining and paucity of deposition in distal areas due to clear floodbasin waters are characteristic of strong front loading that results when suspended sediment production is restricted to channel erosion processes

multi scale hydrogeologic characterization of a leaky till mantled fractured bedrock aquifer system the paper presents hydrogeologic properties for a leaky till mantled fractured bedrock aquifer system based on geophysical and hydraulic tests performed at a drumlin located in northeastern massach

influence of bank vegetation on channel morphology in rural and urban watersheds stream bank vegetation significantly influences the morphology of streams in the piedmont region of the united states we surveyed the morphology of 26 paired stream reaches in southeastern pennsylvania northern maryland and delaware one member of each pair has a forested riparian zone whereas the other has a riparian zone composed pri marily of grass the paired reaches are nearly contiguous so all significant channel forming variables except riparian vegetation are held constant the extent of urban development of the watersheds upstream of the paired reaches also varies considerably allowing us to determine the combined influence of riparian vegetation and urbanization on channel morphology statistical analyses indicate that 1 channels with forested riparian zones are wider than channels with nonforested riparian zones 2 channels in urbanized watersheds are wider than channels in nonurbanized watersheds and 3 the effect of riparian vegetation is independent of the level of urbanization

some chemical characteristics of paleosol humic acids humic acids ha s were extracted from six paleosols in southern italy ranging in radiocarbon ages from 6 000 to 30 000 yr each ha was characterized by a number of chemical elemental and functional group analyses and spectroscopic e4e6 ratios 13c nmr ir esr methods and by chemical degradation followed by separation and identification of the products by gas chromatography mass spectrometry the chemical characteristics of the paleosol ha s were then compared with those of more recent ha s the chemical and spectroscopic methods failed to show any effect of age on the chemical structure of the paleosol ha s only oxidative degradation showed differences between the six paleosol ha s the oxidation of paleosol ha s 22 000 yr old and older produced significantly greater quantities of benzenetetra penta and hexacarboxylic acids than did the oxidation of the younger paleosol ha s and of ha s extracted from soils of volcanic origins these findings indicate that the molecular complexity of the paleosol ha s increased with increasing time of burial

chlorine 36 dating of very old groundwater 1 the great artesian basin australia chlorine 36 has many advantages as a dating tool for very old groundwater these advantages include a suitable half life 3 01 x 10 sup 5 years simple geochemistry conservative behavior in groundwater and a general absence of subsurface sources at levels comparable to the atmospheric input recent advances in tandem accelerator mass spectrometry have permitted the analysis of sup 36 cl at low abundance expected following residence in the subsurface for 10 sup 6 years or more in order to test the suitability of sup 36 cl for dating very old groundwater the sup 36 cl cl ratios of 26 groundwater samples from the great artesian basin of australia have been measured groundwater ages calculated from the sup 36 cl data compare favorably with ages computed independently from hydrodynamic simulations

anatomy and dimensions of fluvial crevasse splay deposits examples from the cretaceous castlegate sandstone and neslen formation utah u s a abstract crevasse splay deposits form a volumetrically significant component of many fluvial overbank successions up to 90 in some successions yet the relationships between the morphological form of accumulated splay bodies and their internal facies composition remains poorly documented from ancient successions this work quantifies lithofacies distributions and dimensions of exhumed crevasse splay architectural elements in the campanian castlegate sandstone and neslen formation mesaverde group utah usa to develop a depositional model fluvial crevasse splay bodies thin from 2 1 m average to 0 8 m average and fine from a coarsest recorded grain size of lower fine sand to fine silt away from major trunk channel bodies internally the preserved deposits of splays comprise laterally and vertically variable sandstone and siltstone facies associations proximal parts are dominated by sharp and erosional based sandstone prone units which may be structureless or may comprise primary current lineation on beds and erosional gutter casts medial parts comprise sets of climbing ripple strata and small scale deformed beds distal parts comprise sets of lower stage plane beds and complex styles of lateral grading into fine grained floodbasin siltstones and coals lithofacies arrangements are used to establish the following i recognition criteria for crevasse splay elements ii criteria for the differentiation between distal parts of crevasse splay bodies and floodplain fines and iii empirical relationships with which to establish the extent ca 500 m long by 1000 m wide and overall semi elliptical planform shape of crevasse splay bodies these relationships have been established by high resolution stratigraphic correlation and palaeocurrent analysis to identify outcrop orientation with respect to splay orientation this permits lateral changes in crevasse splay facies architecture to be resolved facies models describing the sedimentology and architecture of crevasse splay deposits preserved in floodplain successions serve as tools for determining both distance from and direction to major trunk channel sandbodies

stream channels in peatlands the role of biological processes in controlling channel form while some aspects of peatlands are well studied understanding of the hydrology and geomorphology of the associated surface drainage networks is quite limited this paper attempts to describe some of the basic attributes of stream channels in peatlands and asks whether the form and the mechanisms behind development represent a significant departure from self forming alluvial streams we use three approaches to better understand these poorly studied systems an examination of the geomorphology of allequash creek wisconsin a survey of aerial photographs of similar peatland stream complexes in northern wisconsin and a review of the existing literature on peat influenced and wetland channels distinct features of allequash creek and other wisconsin streams in peatlands include absence of mineral substrates low width depth ratio presence of lateral pool like structures along the channel margin long straight reaches and acute angle bends further the lateral location of the thalweg was apparently independent of planform or cross sectional form and no flow zones often occurred along both edges of channel cross sections collectively these features represent a distinct departure from characteristic forms of alluvial channels deep peat samples from allequash creek and aerial photographs from other sites indicate that these streams represent remnant lake systems whose basins filled with peat thus we suggest that the processes responsible for channel form in these low energy peatland systems are largely governed by groundwater hydrology and the biology of peat accumulation and decomposition in this manner biological forces not just physical drivers such as channel discharge and sediment supply are central to the understanding of stream geomorphology in peatlands

source rock potential of the phosphorite bituminous chalk marl sequence in jordan abstract the phosphorite and the overlying oil shale succession in central and eastern jordan has been studied for its organic matter composition maturation hydrocarbon potential and sedimentological implications pristine phosphorite was authigenically precipitated from interstitial solutions in ventilated environments later they were reworked and winnowed to produced the granular phosphorites possibly as wave or storm sand bodies the oil shale was deposited in the same basins where restricted water circulation and subsequent hypersalinity led to more reducing conditions and better organic matter preservation both facies represent a high bio productivity regime associated with paleo upwelling on the shallow southern epicontinental shelf of the tethys ocean the organic matter is dominantly amorphous and the extractable part is high kerogen is type ii s to type iii all maturity parameters investigated proved it to be immature e g r0

age dating of groundwater in fissured rock influence of water volume in micropores age dating of groundwater by 14c measurements is sometimes used to indicate the residence time of the water in fissured rock with a porous rock matrix the flow is in the fissures the water filled pores of the rock may however be accessed by the tracer by diffusion the residence time for a tracer can then be longer than the flow time model calculations were performed using data for granitic rock for flow in large fissures 1 mm the 14c age is 10 70 times larger than the water residence time for small fissures 0 01 mm the 14c age may be more than 1000 times larger

depositional patterns following the 1870s avulsion of the saskatchewan river cumberland marshes saskatchewan canada abstract the avulsion of the saskatchewan river cumberland marshes east central saskatchewan canada has resulted in new floodplain deposition over an area of more than 500 km2 since beginning in the 1870s the avulsion deposits are predominantly fine grained and could be otherwise classifiable as overbank sediments in alluvial floodplains presumed to be supplied by intermittent flooding of dominant master channels the north angling and cadotte channels are older pre existing channels that were intercepted and appropriated by the expanding avulsion following annexation of the north angling channel stable cohesive banks inhibited channel enlargement and crevassing forcing the increasing discharges to be accommodated by overbank flow and in the process enhancing new levee aggradation these levee deposits coarsen upward and thin downstream as a result of greater competence and higher proximal deposition rates brought on by the larger flows in contrast the cadotte channel responded to increasing discharges by levee breaching giving rise to splay progradation and floodbasin filling the cadotte splay complex formed from the avulsively annexed cadotte channel represents a small but typical area of the avulsion belt facies characteristics and interrelationships examined from auger borings and vibracores are presented to illustrate patterns of deposition and floodplain development avulsive flooding initially raised local water surface elevations deepening small existing lakes and creating new shallow 1 2 m deep lakes on the floodplain surface deposition began when levees of the cadotte channel were breached allowing water and coarser sediment to spread as sheet like flows while finer sediment was carried and deposited farther into the basin later as the proximal splay sheets coalesced and grew basinward flows became channelized and progradation of mouth bars into marshes and shallow lakes together with deposition of interchannel fines became dominant forming coarsening upward sequences further floodplain aggradation developed by overbank flooding when splay channels became stabilized and bordered by levees gradual abandonment was accompanied by deposition of organic rich fine grained sediment on top of the progradational sequences throughout the avulsion the north angling channel has stood as an older alluvial ridge separating two broad areas of avulsive deposition its recent levee deposits now grade basinward into these new floodplain sediments composed of thicker heterogeneous predominantly upward coarsening and rapidly deposited facies of the avulsion

dating very old pore waters in impermeable rocks by noble gas isotopes the sup 4 he sup 40 ar and sup 136 xe content dissolved in the pore water of sedimentary rock samples was measured on samples from borehole cores near the repository for nuclear waste in morsleben germany due to the very low permeabilities of the rock formations conventional groundwater sampling was almost impossible hence the authors developed a new sampling method for noble gases in the pore water of freshly drilled rock cores this method provides vertical noble gas profiles in high depth resolution even in impermeable rocks by application of the new technique quantitative age information of groundwater and pore water have been derived the authors find palaeowaters from the last glaciation depleted in delta d and delta sup 18 o with a sup 4 he age of about 55 kyr the high saline pore solutions below are at least 6 mio years old this has been concluded from the profiles of radiogenic sup 4 he and sup 40 ar close to diffusion in steady state and from xenon isotopes produced by spontaneous fission of sup 238 u in the rocks a sup 4 he flux of 2 center dot 10 sup minus 7 cc stp cm sup 2 yr is derived from the profile which is due to local sup 4 he production within the investigatedmore sediments less

chloride and chlorine isotopes 36cl and δ37cl as tracers of solute migration in a thick clay rich aquitard system detailed vertical profiles of dissolved cl and its isotopes 36cl and 37cl provided new information on the origin and systematics of this conservative tracer in pore waters of a thick aquitard system the aquitard system consists of surficial quaternary clay rich till 80 m thick deposited 30 20 kyr b p overlying cretaceous marine clay 76 m thick deposited 71 ma the distribution of cl 37cl and br showed the presence of five distinct end members for cl the top of the unoxidized till a regional aquifer underlying the cretaceous clay two localized geological heterogeneities sand streaks in the till and glacial meltwater emplaced with the till and still present at depths of between 36 and 60 m numerical simulations of the transport of cl from the sand streaks indicated that this geochemical profile has been developing throughout most of the holocene the 36cl measurements showed that the age of the dissolved cl in the upper cretaceous clay is likely between 0 75 and 1 9 myr the 36cl measurements further suggested that the dissolved cl in the till was not directly derived from the underlying cretaceous clay finally it was not possible to quantify the effects of isotopic fractionation of 37cl relative to 35cl because of diffusion in this aquitard system

the middle and late pleistocene loess soil record in the iskitim area of novosibirsk priobie south eastern west siberia the pleistocene loess soil sequence from west siberia has provided a continuous record of quaternary climate change in northern asia the middle late pleistocene loess paleosol stratigraphy of west siberia has become recently a subject of discussion after a considerable revision was suggested by equating the shipunovo pedocomplex to the late pleistocene stage 5 mis 5 instead of the previous correlation with the middle pleistocene stage mis 9 the revision however was made using data from a single sampled section marble quarry site without proper reference to the local geology to links of the loess and soil units traceable between the lozhok and marble quarries and to deposition hiatuses we compare the loess soil stratigraphy at the marble quarry site iskitim area novosibirsk priobie plateau upper ob reaches with the continuous record of the nearby lozhok quarry and evidence from boreholes in the quarry bottom to show that the shipunovo pedocomplex does correlate with mis 9 mis 5 is the time of the berdsk complex formation the two complexes have many features of difference thickness and maturity of soil profiles thickness and expression of humus and illuviation horizons distribution of calcium carbonate concentrations within the soil profiles patterns of soil formation processes and cryoturbation and stratigraphy the lozhok quarry section comprising five pedocomplexes intercalated in loess is continuous and almost free from hiatuses the marble quarry section in the berd high terrace in contrast does not contain some stratigraphic units including the berdsk and koinikha pedocomplex the gaps being indicated by coarse sand and gruss at the base of loess layers therefore the study has demonstrated the previously suggested pleistocene loess soil stratigraphy in southeastern west siberia

characterization of a diffusion dominant system using chloride and chlorine isotopes 36cl 37cl for the confining layer of the great artesian basin australia abstract the great artesian basin gab australia one of the largest confined aquifer systems in the world attracts great attention for groundwater dating however there is little information about the confining layers therefore core drilling investigations were conducted to characterize the main confining layer using chloride cl and chlorine isotopes 36cl 37cl at marree south australia and richmond queensland which are near the discharge and recharge areas in the gab respectively pore water samples were collected from rock cores by squeezing and leaching the cl concentration 36cl cl ratio and 37cl value in the confining layer decreased with depth at both marree and richmond the 36cl cl ratios at the shallower part of the confining layer are significantly higher than the in situ secular equilibrium 36cl clse calculated from the chemical compositions of the rock the 36cl cl ratio logarithmically decreased with depth the calculated 36cl clse is equivalent to the lowest 36cl cl ratio at richmond in contrast the 36cl cl ratios at marree are higher than the calculated 36cl clse the 36cl clse was reached at richmond but not at marree this probably reflects the transport time due to the difference in diffusion coefficients the 37cl value becomes more negative toward the deeper levels reaching 4 5 and 6 1 at marree and richmond respectively these results suggest that the cl is of meteoric origin and is transported by diffusion in the confining layer analytical simulations using diffusion equations were conducted to reproduce excess 36cl 36clex cl and 37cl the 36clex profile which logarithmically decreased with depth was reproduced by steady state diffusion equations with radioactive decay and the diffusion coefficients derived from the 36clex profile were equivalent to those from the laboratory experiments a grid search simulation using an unsteady state diffusion equation was conducted to reproduce the cl and 37cl profiles the cl and 37cl profile could be reproduced however the cl concentration could not be reproduced well at shallower depths further studies are required regarding the geological events on the initial and boundary conditions the diffusive flux from the confining layer to the aquifer is significant in marree but not in richmond though the 37cl can be a good index of diffusive flux however it is difficult to evaluate diffusive flux quantitatively when the diffusive flux is significant because it depends on the transport parameters in the confining layer the groundwater flow in the confining layer is less than 1 10 5 m y because diffusion is dominant

factors affecting the accumulation of organic rich deposits in a modern avulsive floodplain examples from the cumberland marshes saskatchewan canada since the 1870s the saskatchewan river at the cumberland marshes east central saskatchewan canada has been undergoing progradational avulsion resulting in development of a 500 km2 avulsion belt the avulsion belt consists of an unstable network of active and abandoned channels splays and floodbasins some containing small shallow lakes fine grained deposits of varying total organic content toc are currently accumulating within floodbasins inside adjacent to and outside the avulsion belt the toc of these deposits depends on factors that control the amount of siliciclastic sediment received by floodbasins five factors that affect toc content are identified distance from an active channel position relative to the avulsion belt presence of alluvial ridges changes in local channel activity and developmental stage of avulsion a channel to basin trend of increasing toc is present at many locations reflecting greater suspended sediment loads received by near channel areas and locations within the avulsion belt generally accumulate sediment with lower toc than those adjacent to or outside the belt alluvial ridges locally act as barriers to floodbasin deposition and channel abandonment reduces suspended sediment to adjacent floodbasins both of which increase toc of sediment finally as avulsion wanes less siliciclastic sediment is distributed throughout the avulsion belt resulting in increased toc in the geological record such fine grained avulsion deposits are likely to appear as intervals of mudrock between thin beds of coal or carbonaceous shale formed from organic rich sediment deposited between avulsion events a succession that is common in many ancient alluvial strata

post depositional remanent magnetization lock in and the location of the matuyama brunhes geomagnetic reversal boundary in marine and chinese loess sequences article i nfo pdrm lock in loess paleosol bioturbation disturbs detrital magnetic particles after deposition so accurate recording of the ancient geomagnetic field in bioturbated sediments is widely attributed to acquisition of a post depositional remanent magnetization pdrm whereby the geomagnetic field exerts a torque on a magnetic particle and aligns it with the field after the final mixing event experienced by the particle the relationship between the matuyama brunhes boundary mbb and oxygen isotope age tie points in marine sediments has been widely used to determine the depth at which the paleomagnetic signal is locked in however such analyses can be badly affected by age discrepancies among different paleoclimatic proxies and by varying isotopic compositions of seawater in different locations and from the presence of different water masses at different depths at the same location it is therefore necessary to separately compare paleomagnetic data with respect to either benthic or planktonic foraminiferal oxygen isotope records for sites from the same water mass to avoid inadvertently introducing age differences to the analysis when the global data set is subjected to such a rigorous analysis few reliable data remain for the mbb using two complementary approaches we estimate that the mbb is on average shifted 20 cm below its true position in marine sediments this offset is the sum of the thickness of the bioturbated surface mixed layer which is possibly dominant and the pdrm lock in depth there is also controversy concerning observed differences in the position of the mbb relative to paleoclimatic proxies in marine sediments and chinese loess deposits for the chinese loess quartz grain size is insensitive to pedogenic alteration and is a useful parameter for determining the true position of the mbb with respect to paleoclimatic boundaries we conclude that the mbb occurs late in marine oxygen isotope stage 19 and in the upper part of chinese paleosol unit s8 rather than at the mid or lower part of loess unit l8 our results require adjustment of the generally accepted positions for the mbb and resolve a longstanding chronological conundrum for marine and chinese loess sequences

chloride bromide δ11b systematics of a thick clay rich aquitard system boron cl and br concentrations and boron isotopic compositions 11b were used to provide insight into the sources and water sediment interactions of fossil water in a thick nonfractured aquitard system in saskatchewan canada the aquitard system consists of 80 m of late pleistocene clay rich till disconformably overlying 77 m of late cretaceous marine clay the clay is underlain by a regional sand aquifer variations in cl and br confirmed the presence of well defined conservative mixing relationships between four types of fluids present in the aquitard system 1 low cl water from the base of the fractured and oxidized till zone at 4 m depth 2 water characterized by an elevated cl peak 190 mg l at about 12 m 3 glacial meltwater present between 20 and 60 m depth and 4 more saline water cl up to 1000 mg l from the underlying cretaceous clay and sand aquifer glacial meltwater has low cl 11b 20 and cl br ratios 50 the low cl br ratio of the glacial meltwater is similar to that of modern inland precipitation which suggests that the br budget in the atmosphere 20 30 ka b p was similar to that of today and that br enrichment in the atmosphere may be a natural process the relatively low cl br ratio 150 and 11b values of the saline water in the sand aquifer 35 and 39 respectively and pore water in the cretaceous clay 25 6 and 32 6 respectively are not consistent with simple dilution of seawater but suggest dilution and modification of fifteenfold evaporated seawater with a low cl br and a high 11b value 39 this evaporitic seawater may have been entrapped in the cretaceous clay upon or after its deposition and subsequently flushed from the clay by fresher water we suggest that the refreshening process modified the original brine into na hco3 water type and extracted boron with 11b 39 from the adsorbed sites in contrast increase of cl in the upper section of the till the 12 m peak resulted in apparent depletion of dissolved boron and relative 11b enrichment which can be explained by adsorption processes the b 11b relationships can thus be used to trace water clay interactions in aquitard systems

geochemical evidence for efficient aquifer isolation over geological timeframes aquitards layers of rock having low permeability have been suggested as potential long term reservoirs for toxic materials such as nuclear or chemical waste but information about the isolation properties of aquitard layers is essential to evaluate whether they can indeed be used safely as reservoirs here we investigate the long term mobility of groundwaters between two aquifers surrounding an aquitard layer in the eastern recharge area of the paris basin france using helium isotopes as a geochemical tracer the deeper trias sandstone aquifer which lies above the crystalline basement accumulates radiogenic 4he and primordial 3he from large regions of the crust and mantle at rates comparable to the degassing of the whole crust1 and of mid ocean ridges2 we show that the overlying carbonate dogger aquifer which is separated from the trias aquifer by an aquitard layer consisting of a 600 m succession of shales and clays is stagnant and has been extremely well isolated from the trias over the past several million years this finding together with previous studies at the centre of the paris basin3 4 shows that diffusive mass transfer across aquitards is negligible and that cross formational flow in basins takes place preferentially in faulted areas

patterns of alluvial rivers the pattern planform of a river can be considered at vastly different scales depending upon both the size of the river and the part of the fluvial system that is under consideration figure 1 for example in the broadest sense river patterns comprise a drainage network dendritic parallel trellis etc figure la the type of pattern is of interest to geomorphologists and geologists who interpret geologic conditions from aerial photographs at another scale a river reach which in figure lb is meandering is of interest to the geomorphologist who is interested in what that pattern reveals about river history and behavior and to the engineer who is charged with maintaining navigation and preventing major instability when a single meander is examined figure 1 c the hydraulics offtow the sediment transport and the potential for bank erosion are of concern in addition the sedimentologist is interested in the distribution of sediment within the bend bed forms within the channel figure ld and sedimentary structures figure ie which also establish a component of roughness for the hydraulic engineer finally the individual grains figure if provide geologic information on the sediment sources the nature of sediment loads and the feasibility of dredging for gravel there is an interaction of hydrology hydraulics geology and geomorphology at all scales which emphasizes the point that the fluvial system as a whole cannot be ignored even though only a component of the system is to be studied in this review only the patterns or planforms of alluvial rivers are discussed although it is apparent that the hydrologic and sediment yield characteristics of the drainage basin figure la as well as its geologic history cannot be ignored in the explanation of the pattern of any river

testing helium equilibrium between quartz and pore water as a method to determine pore water helium concentrations abstract the effectiveness of carbon capture and geologic storage depends on many factors including and especially the permeability of the reservoir s caprock while caprock integrity is generally assumed if petroleum has been preserved it is poorly constrained in reservoirs containing only saline waters and co2 leakage poses a potential risk to shallow aquifers naturally occurring he accumulates in pore waters over time with the concentration being strongly dependent on the long term flux of fluid through the caprock furthermore a small fraction of pore water he diffuses into quartz and this may be used as a proxy for he concentrations in pore water where dissolved gas samples are difficult to obtain such as in deep sedimentary basins in this paper he contained in quartz grains is measured and compared to previously measured pore water concentrations quartz was purified from core samples from the san juan basin new mexico and the great artesian basin south australia quartz separates were heated at 290 c to release he from the quartz the quartz from the san juan basin and high purity quartz from the spruce pine intrusion north carolina was repeatedly impregnated at varying pressures using pure he heated and analyzed to build he sorption isotherms the isotherms appear linear but vary between samples possibly due to fluid inclusions within the quartz grains as high purity quartz samples partition only 1 5 of he that partitions into san juan basin samples concentrations of he in the pore water were calculated using the he accessible volume of the quartz and the air water he solubility the mean san juan basin he pore water concentration was 2 10 5 cc stp he g water 400 times greater than atmospheric solubility great artesian basin samples contain a mean he concentration of 3 10 6 cc stp he g water or 65 times greater than atmospheric solubility however pore water he concentrations in both the san juan and great artesian basins differ by up to an order of magnitude compared to samples collected with an alternate method the reason for the offset is attributable to either partial saturation of the pore volume or a lack of he equilibrium between quartz and pore water coating of clay or other mineral phases on quartz grains which tends to reduce the effective diffusion coefficient may cause the latter this technique of assessing permeability is promising due to the abundance of existing core samples from numerous basins where carbon sequestration may ultimately occur

holocene avulsion styles and sedimentation patterns of the saskatchewan river cumberland marshes canada abstract this paper describes the styles and sedimentation patterns of holocene avulsions of the saskatchewan river at the cumberland marshes predating the most recent 1870 s avulsion holocene avulsions involved two major styles 1 progradation of lacustrine deltas and splay complexes and 2 local reoccupation or appropriation of preavulsive channels most avulsions were progradational and occurred in floodplain lakes occupying floodbasin areas between elevated alluvial ridges the two most recent avulsions old channel and 1870 s diverted mainly into inundated peatland progradational avulsions were accompanied by deposition of avulsion belt sediments associated with multiple channel networks the characteristics of avulsion belt deposits include 1 sediments dominated by poorly sorted silt and very fine sand 2 lateral continuity in transverse and longitudinal directions with subhorizontal upper and lower boundaries 3 predominantly nonerosional contacts with underlying sediments 4 coarsening upward successions 5 consistent radiocarbon dates for the tops of preavulsive substrates and 6 occurrence beneath levee and overbank deposits of the associated major channel belt indicating that avulsion belt deposition occurs prior to the development of a new master channel the width of ancient avulsion belts reaches 18 km with typical thicknesses of 2 3 m avulsion belt deposition accompanied by many small channels was followed by flow reversion to a few larger channels and eventually to one single channel accompanied by deposition of levee and channel deposits reoccupational avulsions were not accompanied by deposition of widespread avulsion belt sediments and led mainly to the modification of pre existing channel belts the sedimentation patterns of holocene avulsions of the saskatchewan river reveal that avulsion belt sediments represent major components of the floodplain deposits supporting the model developed from observations of the 1870 s avulsion

contribution of logging tools to understanding helium porewater data across the mesozoic sequence of the east of the paris basin abstract helium concentration measurements made on water and rock samples collected at various depths along a 2000 m depth borehole drilled in the eastern part of the paris basin and reaching the triassic conglomerates were used to establish a vertical profile of dissolved helium concentration throughout the entire mesozoic sedimentary pile wireline logging tools were used to measure rock density porosity and u and th contents every 15 cm in the various formations samples from the deepest muschelkalk and buntsandstein show a very good agreement between measured and calculated 4he porewater contents shallower levels show lower and lower 4he concentrations compared to calculated values when going upwards the data set obtained by wireline logging measurements was used as inputs for numerical simulations of 1d he production diffusion throughout the 2000 m profile several assumptions regarding the transport properties in the various sedimentary layers were tested and all were found to yield fairly good agreement between modeled and measured he concentrations there is no need to invoke either a transient regime or a deep crustal he flux in this quiet seismically inactive part of the paris basin moreover the modeling results suggest that the keuper massive halite level associated with the upper muschelkalk pre evaporitic series efficiently isolates the overlying layers from any input from deeper formations in the meuse haute marne area

natural tracer profiles across argillaceous formations argillaceous formations generally act as aquitards because of their low hydraulic conductivities this property together with the large retention capacity of clays for cationic contaminants has brought argillaceous formations into focus as potential host rocks for the geological disposal of radioactive and other waste in several countries programmes are under way to characterise the detailed transport properties of such formations at depth in this context the interpretation of profiles of natural tracers in pore waters across the formations can give valuable information about the large scale and long term transport behaviour of these formations here tracer profile data obtained by various methods of pore water extraction for nine sites in central europe are compiled data at each site comprise some or all of the conservative tracers anions cl br water isotopes delta 18 o delta 2 h and noble gases mainly he based on a careful evaluation of the palaeo hydrogeological evolution at each site model scenarios are derived for initial and boundary pore water compositions and an attempt is made to numerically reproduce the observed tracer distributions in a consistent way for all tracers and sites using transport parameters derived from laboratory or in situ tests the comprehensive results from this project have been reported in mazurek et al 2009 here the results for three sites are presented in detail but the conclusions are based on model interpretations of the entire data set in essentially all cases the shapes of the profiles can be explained by diffusion acting as the dominant transport process over periods of several thousands to several millions of years and at the length scales of the profiles transport by advection has a negligible influence on the observed profiles at most sites as can be shown by estimating the maximum advection velocities that still give acceptable fits of the model with the data the advantages and disadvantages of different conservative tracers are also assessed the anion cl is well suited as a natural tracer in aquitards because its concentration varies considerably in environmental waters it can easily be measured although the uncertainty regarding the fraction of the pore space that is accessible to anions in clays remains an issue the stable water isotopes are also well suited but they are more difficult to measure and their values generally exhibit a smaller relative range of variation chlorine isotopes delta 37 cl and he are more difficult to interpret because initial and boundary conditions cannot easily be constrained by independent evidence it is also shown that the existence of perturbing events such as the activation of aquifers due to uplift and erosion leading to relatively sharp changes of boundary conditions can be considered as a pre requisite to obtain well interpretable tracer signatures on the other hand gradual changes of boundary conditions are more difficult to parameterise and so may preclude a clear interpretation

fine grained splay deposition in the avulsion belt of the lower saskatchewan river canada abstract in or about 1883 a northward avulsion of the meandering lower saskatchewan river at the cumberland marshes initiated a broad belt of alluvial sedimentation that has continued to evolve to the present and now covers some 500 km2 the avulsion belt comprises a complex alluvial terrain dominated by individual and coalesced splays and associated wetlands connected by networks of active and abandoned channels of various sizes the windy lake splay a predominantly fine grained feature typical of large parts of the avulsion belt was examined to investigate the relationships between splay evolution and facies development the splay now largely inactive mostly formed over a 35 year period depositing nearly 2 m of sediment over a 7 2 km2 area the splay surface is ch racterized by stable well defined anastomosed distributary channels that separate interchannel wetland basins heights of channel levees diminish downstream and the levees merge with channel mouth bars whose progradation forms the locus of lakeward channel extension and the base for subsequent subaerial levee deposition the anastomosed channel pattern was created when the mouth bars of separate distributary channels merged during progradation vibracore and soil probe profiles show the splay to be dominated by upward coarsening lacustrine prodeltaic mouth bar facies sequences capped by levees and organic rich interchannel wetland deposits channels now containing sand only sporadically in narrowed or slightly migrated reaches will eventually fill with fine sediment when abandonment s complete the windy lake splay is typical of stage iii splays smith et al 1989 whose deposits and associated lacustrine fills form at least half of the avulsion belt thin widespread predominantly upward coarsening sequences capped by either nondepositional horizons or true overbank fines may be characteristic of many avulsive suites in the ancient alluvial record

depositional development of the muskeg lake crevasse splay in the cumberland marshes canada crevasse splays are common geomorphological features in alluvial and deltaic floodplains although crevasse splays can develop into full avulsions thereby transforming large areas of floodbasins little is known about their sedimentary and geomorphological development at the decadal scale and their avulsion potential we used aerial photography and lithological cross sections to reconstruct crevasse splay formation in the largely unmanaged floodplain of the saskatchewan river in the cumberland marshes saskatchewan canada based on surface geomorphology and subsurface deposits various stages of crevasse splay development were described which were linked to both external forcing and internal morphodynamics initial splay deposition following a levee breach during a large flood occurred as a broad but relatively thin sandy sheet in a down basin direction in the receiving backswamp area in a next phase these primary crevasse splay deposits blocked local down basin flow thereby forcing the crevasse splay channel in a direction perpendicular to the parent channel and original floodbasin gradient this created an asymmetrical splay sequence composition which differs in appearance from more commonly observed dendritic crevasse splays it is concluded that sedimentation patterns in the splay have been influenced by inherited effects of previously formed deposits feedbacks of the original floodbasin gradient and earlier stages of splay formation are suggested as prominent mechanisms in creating the current morphology orientation and architecture of its deposits

phosphorus pathways in atolls interstitial nutrient pool cyanobacterial accumulation and carbonate fluoro apatite cfa precipitation significant dissolved phosphate concentrations were measured in reef interstitial waters and in small brackish ponds free water and underlying interstitial water occupying the emerged rim of the tuamotu atolls french polynesia these ponds are the sites of accumulation of organic matter of pure microbial origin in the form of thick stromatolitic cyanobacterial mats called kupara by tuamotu natives the profiles of dissolved phosphate interstitial waters seem to show a positive trend with depth within kopara the phosphorus pathway after biological uptake is studied by measuring the c and p concentrations in raw material and in humic substances humin fulvic and humic acids in order to examine the liberation of p from organic matter for comparison the same analysis is led on the residual organic matter of phosphate samples from mataiva deposit tuamotu the results show a relative enrichment in phosphorus with age of kopara and a similar distribution of humic substances in kopara and phosphate samples other work on hydrocarbons from kopara and phosphate samples demonstrates the strong relationship of these materials if such evolution of organic matter can be observed in kopara ponds it should be possible to generalize to closed atoll lagoons which function as mega kopara ponds and where phosphorus rich layers are present e g the niau atoll the different steps leading to atoll phosphogenesis viewed as phosphorus sink in cyanobacterial mats to final massive cfa accumulation could then be rationally explained the interstitial nutrient pool can be a necessary and sufficient factor to provide phosphorus for the kopara growth and accumulation o elsevier science b v all rights reserved keyvords interstitial nutrients cyanobacterial mats apatite precipitation

the 1870s avulsion of the saskatchewan river several major avulsions of the saskatchewan river have occurred in the cumberland marshes east central saskatchewan during the past few thousand years the most recent avulsion occurred in about the 1870s converting over 500 km2 of floodplain into a belt of anastomosing channels splay complexes and small lakes a region that is still evolving today the avulsion began near the tip of a large meander bend by following a small outflowing creek sturgeon river which in turn followed an abandoned former channel of the saskatchewan river flow began to permanently divert out of the saskatchewan when a narrow strip of floodplain separating the sturgeon river from the nearby torch river became breached diversion into the connected sturgeon torch began to increase sometime in the 1870s and probably culminated around 1882 the triggering event for the avulsion may have been a chute cutoff of the meander bend shown by numerical modeling experiments to have significantly raised water surface elevations at th

the sedimentary record of carboniferous rivers continuing influence of land plant evolution on alluvial processes and palaeozoic ecosystems abstract evidence from modern rivers and the deep time geological record attests to the fundamental importance of plant life for the construction of physical habitats within fluvial environments data from an extensive literature review and original fieldwork demonstrates that many landforms and geomorphic features of modern river systems appear in the palaeozoic stratigraphic record once terrestrial vegetation had adopted certain evolutionary advances for example stable point bars are associated with the onset of rooted plants in the siluro devonian and avulsive and anabranching fluvial systems become common at the same time as extensive arborescent vegetation in the carboniferous in this paper we demonstrate a correlation between the diversification of physical fluvial environments and the expansion of terrestrial fauna and flora with an emphasis on the culmination of these trends within carboniferous alluvial systems many extrinsic factors have been considered as possible controls on the evolutionary timelines of terrestrialization for organisms however a fundamental prerequisite for achieving terrestrial biodiversity was the variety of physical habitats especially riparian systems available for newly evolved organisms in association with abundant lowland meandering systems the widespread appearance across carboniferous alluvial plains of fixed channel and anabranching reaches created further physical landforms for colonization and would have promoted increasingly complex hyporheic flow regimes furthermore the associated increase in arborescent vegetation and supply of large woody debris to inland and coastal rivers would have created a wealth of microhabitats for continental organisms we argue that the expanding extent and diversity of physical alluvial niches during the palaeozoic is an underappreciated driver of the terrestrialization of early continental life the study of the deep time fossil and stratigraphic record also illustrates that vegetation is a fundamental prerequisite for the creation of biogeomorphic alluvial landforms and physical habitats and microhabitats

the paks loess paleosol sequence a record of chemical weathering and provenance for the last 800 ka in the mid carpathian basin abstract the paks loess paleosol sequence is one of the most important terrestrial records of middle and late pleistocene environmental changes in east central europe spanning the last ca 0 8 ma while geochemical proxies demonstrate a general decreasing chemical weathering trend over the last 0 8 ma in the carpathian basin mineralogy and derived indices reflect intensifying physical erosion in theory the observed chemical weathering trend can be accounted for both by enhanced input of relatively unweathered material and by climate deterioration during the quaternary as the proxies such as cia are not capable of distinguishing between pre and post depositional weathering enhanced physical erosion of the source areas driven by tectonism and resulting increased sedimentation of fresh mineral dust at the depositional site are demonstrated by increasing dolomite illite and chlorite contents and sme ill sme ill chl ratios from older to younger sediments in the profile together with increasing thickness of loess layers towards the youngest part of the sequence at the same time constant smectite contents 30 40 in paleosols appear to disprove progressive aridization of interglacials through time and suggest that the duration of pedogenesis played an important role in determining soil types further the increasing proportion of inherited phyllosilicates illite and chlorite would in theory raise the possibility that the decreasing values of chemical weathering indices are just artifacts of enhanced physical erosion and resulting increased dust deposition by a dilution effect the above findings highlight the fact that the general view on chemical weathering is oversimplistic as its equation includes two basic variables tectonism and time beyond climate and the interplay of these equally important factors will eventually determine its final value to get a better grasp of these processes needs further data more age control in loess profiles data on uplift in and around sedimentary basins and more sophisticated proxies as the mineralogical data presented here can be considered only semiquantitative regarding the provenance of sediments in the paks profile geochemical data demonstrate that felsic rocks dominated the source areas and there have been only very little variations in provenance over the last ca 0 8 ma significant contributions from mafic ultramafic rocks to the sediments can be ruled out as revealed by lower abundances of ferromagnesian trace elements the appearance of amphiboles and high dolomite contents suggest that loess material was at least partly sourced from local rocks and geochemical data reveal a genetic link between floodplain sediments and loess deposits

sedimentology facies architecture and chemostratigraphy of a continental high latitude paleocene eocene succession the chickaloon formation alaska abstract the paleocene eocene chickaloon formation of southern alaska represents rapid deposition in a floodbasin setting contains abundant and diverse fossil plant material and spans the paleocene eocene thermal maximum petm sedimentologic lithofacies and chemostratigraphic analyses of exposures of the chickaloon formation were conducted in order to provide a contextual framework for this late paleocene early eocene high latitude sedimentary succession and to test if hyperthermal conditions are recorded in the unit at the main study area in the evan jones coal mine strata represent an alluvial sequence dominated by floodplain channel sandstone crevasse lobe crevasse channel and mire deposition floodplain environments are represented by medium gray commonly nodular and or carbonate cemented shaly siltstone and centimeter scale thick sheet sandstone interbeds most channel sandstone deposits are interpreted to be crevasse channels and are generally small 2 5 m thick rarely coarser than medium grained sandstone and sand grains are commonly coated with fe oxides carbonaceous shale and coal are localized and indicate a high rate of organic carbon accumulation in the area 13c analyses of bulk organic carbon from the succession at the evan jones mine are internally consistent with this interpretation they yield uniformly negative values that are typical of continental organic matter 21 7 to 28 5 x 25 4 fossil plant material is also very common and includes leaves wood seeds and resins from broad leaf angiosperms conifers ferns and sphenopsids considered together lithologic and paleontologic data suggest that these strata represent a floodbasin environment the observed crevasse channels probably originate from a main channel located within several kilometers of the depocenter ash fall tuffs punctuate the studied sequence and contain abundant reworked or recycled zircons indicating that the depocenter was proximal to a volcanic source across all of these chickaloon depositional environments a significant negative isotopic shift 5 8 occurs which we hypothesize to represent a short lived perturbation associated with a global hyperthermal event

using excess 4he to quantify variability in aquitard leakage summary fluid flux through aquitards controls the rate of recharge discharge cross formational fluid flow and contaminant transport in subsurface systems in this paper concentrations of 4 he are used to investigate the spatial distribution of vertical fluid flux through the regionally extensive great artesian basin aquitard system in northern south australia two vertical profiles of 4 he concentration in aquitard pore water augmented with regional sampling of aquifers above and below the aquitard were used to estimate fluid flux at multiple locations over a large spatial area 4 he concentrations in the shallow aquifer above the great artesian basin range from atmospheric equilibrium to 1000 times enriched over atmosphere fluid flux through the aquitard was estimated by fitting observed helium concentrations at each sampling site with a 1 d model of helium transport through the aquitard estimated fluid fluxes through the aquitard vary over three orders of magnitude across the study area in areas of competent aquitard fluid fluxes are less than 0 003 mm yr and mass transport of helium is dominated by molecular diffusion preferential discharge zones are clearly identifiable with fluid fluxes up to 3 mm yr our results show that fluid flux through a regionally extensive aquitard can be highly variable at large spatial scales and that 4 he concentrations in aquifers bounding the aquitard system provide a convenient and sensitive method for investigating aquitard flux at the regional scale

the occurrence of high molecular weight humic material in recent organic rich sediment from the namibian shelf abstract the molecular size distribution of humic substances has been investigated in two recent sediment samples of different ages taken from a single core sample collected off walvis bay south west africa extractable humic acids were found to be by far the major form of organic carbon in both sediments the near surface younger sample containing predominantly high molecular weight 100 000 molecular weight humic acids and little fulvic acids whilst the deeper older sample contained relatively less humic acid and relatively more fulvic acid of a range of molecular weights a significant age difference was found between the 300 000 molecular weight and the the data suggest that in this rapidly accumulating organic rich sediment the first step en route from the planktonic matter to the humic complexes is direct and rapid incorporation of the biogenic material into high molecular weight humic acids