summer air temperature reconstructions from the last glacial stage based on rodents from the site taillis des coteaux vienne western france the oxygen isotope composition of phosphate from tooth enamel of rodents 18op constitutes a valuable proxy to reconstruct past air temperatures in continental environments this method has been applied to rodent dental remains from three genera arvicola sp microtus sp and dicrostonyx sp coming from taillis des coteaux vienne france this archaeological site contains an exceptionally preserved sedimentary sequence spanning almost the whole upper palaeolithic including seven stratigraphic layers dated from 35 to 17 cal ka bp the abundant presence of rodent remains offers the opportunity to quantify the climatic fluctuations coeval of the various stages of human occupation of the site differences between 18op values of arvicola sp and microtus sp teeth are interpreted as the result of heterochrony in tooth formation as well as differences in ecology mean 18op values of microtus sp are preferentially used to reconstruct summer air temperatures which range from 16 0 3 7 to 19 1 3 1 c throughout the sedimentary sequence however the highest variability is observed during the last glacial maximum

permafrost and climate in europe monitoring and modelling thermal geomorphological and geotechnical responses we present a review of the changing state of european permafrost within a spatial zone that includes the continuous high latitude arctic permafrost of svalbard and the discontinuous high altitude mountain permafrost of iceland fennoscandia and the alps the paper focuses on methodological developments and data collection over the last decade or so including research associated with the continent scale network of instrumented permafrost boreholes established between 1998 and 2001 under the european union pace project data indicate recent warming trends with greatest warming at higher latitudes equally important are the impacts of shorter term extreme climatic events most immediately reflected in changes in active layer thickness a large number of complex variables including altitude topography insolation and snow distribution determine permafrost temperatures the development of regionally calibrated empirical statistical models and physically based process oriented models is described and it is shown that though more complex and data dependent process oriented approaches are better suited to estimating transient effects of climate change in complex mountain topography mapping and characterisation of permafrost depth and distribution requires integrated multiple geophysical approaches and recent advances are discussed we report on recent research into ground ice formation including ice segregation within bedrock and vein ice formation within ice wedge systems the potential impacts of climate change on rock weathering permafrost creep landslides rock falls debris flows and slow mass movements are also discussed recent engineering responses to the potentially damaging effects of climate warming are outlined and risk assessment strategies to minimise geological hazards are described we conclude that forecasting changes in hazard occurrence magnitude and frequency is likely to depend on process based modelling demanding improved understanding of geomorphological process response systems and their impacts on human activity

enrichment and fractionation of rare earth elements in fes and organic rich estuarine sediments receiving acid sulfate soil drainage abstract an understanding of processes controlling the behaviour of rare earth elements rees within estuarine sediments is essential for the effective use of rees as tracers of environmental conditions this study investigates the enrichment and fractionation of rees in sediments with abundant iron monosulfides fes measured as acid volatile sulfide median 156 mol g and organic carbon median 3 2 mmol g we examined sediments collected from a eutrophic estuary in western australia which comprised several sedimentary environments including sites receiving drainage from acid sulfate soils ass in general sediment bound rees were highly soluble in hcl with 1 mol l hcl extractable ree concentrations amounting to 80 of corresponding total concentrations in approximately 70 of samples a mid ree mree enrichment was consistently apparent in all sediment samples with a median mree enrichment value of 1 30 range 1 13 1 50 for the total ree concentrations and 1 26 range 1 17 1 44 in the 1 mol l hcl extractions also a ce anomaly was consistently observed in the sediments examined here with a median value of 1 11 range 0 79 1 58 for the total ree concentrations and 1 19 range 1 04 1 71 in the 1 mol l hcl extracts in general a minor depletion of heavy rees hrees relative to light rees lrees was also apparent in many of the sediments yb la

abundance and fractionation patterns of rare earth elements in streams affected by acid sulphate soils abstract the abundance and shale normalised fractionation patterns of rare earth elements rees were studied in 121 streams of first and second order in an area where acid sulphate soils developed on oxidised sulphide bearing marine sediments are abundant during high water flow events in autumn on which this study focuses the leaching of rees from the acid sulphate soils is extensive resulting in high total ree concentrations up to 1 mg l in streams draining such soils exclusively in these streams there is a general depletion of the heavy rees explained by preferential scavenging of the latter by oxyhydroxides in the deepest soil profile horizons in streams draining areas of glacial till and peat the ree concentrations are several orders of magnitude lower in these streams in contrast to the ree enriched streams there is a depletion of light rees explained most likely by preferential complexation of the middle and heavy rees by dissolved humic substances

pattern of deglaciation of the last late devensian scottish ice sheet evidence from ice marginal deposits in the dee valley northeast scotland the mode of deglaciation of the last scottish ice sheet is assessed from evidence provided by geomorphological mapping and sedimentology ice marginal deposits in the dee valley have a distinctive morphological expression and a characteristically varied sedimentology that strongly resembles those from subpolar glaciers the deposits tend to occur in certain topographic situations which can be accounted for by compression of ice near the margin and formation of an ice cored supraglacial land system a series of recessional stages of the ice front can be mapped demonstrating that active retreat occurred however additional evidence shows there was probably a thin marginal zone of stagnant ice recessional stages are inferred to be stillstands that are considered to be topographically controlled rather than related to climate development of the supraglacial land system during deglaciation suggests that the ice sheet had a polythermal basal regime with a cold based margin this implies that deglaciation took place in northeast scotland while the climate remained cold probably due to a precipitation deficit which agrees well with chronostratigraphic data

hydrological change in southern europe responding to increasing north atlantic overturning during greenland stadial 1 greenland stadial 1 gs 1 was the last of a long series of severe cooling episodes in the northern hemisphere during the last glacial period numerous north atlantic and european records reveal the intense environmental impact of that stadial whose origin is attributed to an intense weakening of the atlantic meridional overturning circulation in response to freshening of the north atlantic recent high resolution studies of european lakes revealed a mid gs 1 transition in the climatic regimes the geographical extension of such atmospheric changes and their potential coupling with ocean dynamics still remains unclear here we use a subdecadally resolved stalagmite record from the northern iberian peninsula to further investigate the timing and forcing of this transition a solid interpretation of the environmental changes detected in this new accurately dated stalagmite record is based on a parallel cave monitoring exercise this record reveals a gradual transition from dry to wet conditions starting at 12 500 y before 2000 a d in parallel to a progressive warming of the subtropical atlantic ocean the observed atmospheric changes are proposed to be led by a progressive resumption of the north atlantic convection and highlight the complex regional signature of gs 1 very distinctive from previous stadial events

ideas about the surface runoff features on mars in their report evidence of recent groundwater seepage and surface runoff on mars 30 june p 2330 1 malin and edgett propose that the seepage and flow of water may have occurred on mars in the recent geologic past on the basis of the observation of a large number of channel features on

diel behavior of rare earth elements in a mountain stream with acidic to neutral ph abstract diel 24 h changes in concentrations of rare earth elements ree were investigated in fisher creek a mountain stream in montana that receives acid mine drainage in its headwaters three simultaneous 24 h samplings were conducted at an upstream station ph 3 3 an intermediate station ph 5 5 and a downstream station ph 6 8 the ree were found to behave conservatively at the two upstream stations at the downstream station ree partitioned into suspended particles to a degree that varied with the time of day and concentrations of dissolved ree were 2 9 to 9 4 fold 190 to 830 higher in the early morning vs the late afternoon the decrease in dissolved ree concentrations during the day coincided with a corresponding increase in the concentration of ree in suspended particles such that diel changes in the total ree concentrations were relatively minor 27 to 55 increase at night across the lanthanide series the heavy ree partitioned into the suspended solid phase to a greater extent than the light ree filtered samples from the downstream station showed a decrease in shale normalized ree concentration across the lanthanide series with positive anomalies at la and gd and a negative eu anomaly as the temperature of the creek increased in the afternoon the slope of the ree profile steepened and the magnitude of the anomalies increased the above observations are explained by cyclic adsorption of ree onto suspended particles of hydrous ferric and aluminum oxides hfo hao conditional partition coefficients for each ree between the suspended solids and the aqueous phase reached a maximum at 1700 hours and a minimum at 0700 hours this pattern is attributed to diel variations in stream temperature possibly reinforced by kinetic factors i e slower rates of reaction at night than during the day estimates of the enthalpy of adsorption of each ree onto suspended particles based on the field results averaged 82 kj mol and are similar in magnitude to estimates in the literature for adsorption of divalent metal cations onto clays and hydrous metal oxides the results of this study have important implications to the use of ree as hydrogeochemical tracers in streams

bioclimatic analysis of rodent palaeofaunas reveals severe climatic changes in southwestern europe during the plio pleistocene abstract a recently developed method in palaeoclimatology bioclimatic analysis which makes it possible to extract a maximum of information from the available mammal proxy data is applied to a succession of fossil rodent assemblages recorded from the pliocene and pleistocene in the iberian peninsula it consists of both qualitative and quantitative models with the capacity to produce a detailed palaeoclimate reconstruction which is consistent with palaeobotanical and isotopic proxy data and the physics of atmospheric models using this method the palaeoclimate of the iberian plio pleistocene is reconstructed with high resolution from 44 fossil rodent assemblages comprising more than a hundred identified species analysis of these assemblages shows that the climatic evolution of the iberian peninsula during the plio pleistocene can be divided into four distinct climatic phases first a long phase of subtropical climate with summer rainfall and winter drought occurred during the ruscinian second between 3 4 and 2 5 my b p there was a cooling phase coincident with the development of the northern hemisphere ice sheets following this cooling a temperate interlude occurred between 2 5 and 1 8 my b p during this phase the mediterranean climate was established permanently in southwestern europe finally during the pleistocene temperate and colder stages were succeeding in relationship with the northern hemisphere glaciations this sequence of climatic changes is linked with the tectonic rising of the central asian and east african plateaus variations in the atmospheric circulation pattern and changes in the mediterranean sea surface temperatures all these factors led to associated changes in the precipitation regime and a latitudinal displacement of the zonal climatic belts

northern iberian abrupt climate change dynamics during the last glacial cycle a view from lacustrine sediments abstract we present a palaeoclimatic reconstruction of the last glacial cycle in iberia ca 120 000 11 600 cal yrs bp based on multi proxy reconstructions from lake sediments with robust chronologies and with a particular focus on abrupt climate changes the selected lake sequences provide an integrated approach from northern iberia exploring temperature conditions humidity variations and land sea comparisons during the most relevant climate transitions of the last glacial period thus we present evidence that demonstrates i cold but relatively humid conditions during the transition from mis 5 to mis 4 which prevailed until ca 60 000 cal yrs bp in northern iberia ii a general tendency towards greater aridity during mis 4 and mis 3 ca 60 000 to 23 500 cal yrs bp punctuated by abrupt climate changes related to heinrich events he iii a complex highly variable climate during mis 2 23 500 to 14 600 cal yrs bp with the mystery interval mi 18 500 to 14 600 cal yrs bp and not the global last glacial maximum lgm 23 000 to 19 000 cal yrs bp as the coldest and most arid period the last glacial transition starts in synchrony with greenland ice records at 14 600 cal yrs bp but the temperature increase was not so abrupt in the iberian records and the highest humidity was attained during the allerod gi 1a to gi 1c and not during the bolling gi 1e period the younger dryas event gs 1 is discernible in northern iberian lake records as a cold and dry interval although iberian vegetation records present a geographically variable signal for this interval perhaps related to vegetation resilience

experimental studies of ree fractionation during water mineral interactions ree release rates during apatite dissolution from ph 2 8 to 9 2 rare earth elements ree release rates were measured during the open system dissolution of natural apatite at 25 c 2 8 ph 9 2 and at ionic strengths ranging from 0 001 to 0 02 mol kg all inlet solutions were ca ree and p free in agreement with previous studies apatite dissolution rates determined from outlet solution ca concentrations decrease monotonically with increasing ph outlet solution molar ree ca ratios differ from that of the dissolving apatite during the experiments this behaviour is interpreted to stem from dissolution or precipitation of minor quantities of rhabdophane ree po4 nh2o this interpretation is supported by solute speciation calculations which indicate that ree are retained in the solid phase when the outlet fluids are supersaturated with respect to nd rhabdophane ksp 10 24 5 0 5 but preferentially released when the outlet fluids are undersaturated with respect to nd rhabdophane the relative concentrations of the ree in the outlet solutions suggest that the secondary rhabdophane is slightly enriched in light ree ce to eu the results of this study suggest that rhabdophane dissolution and precipitation during apatite fluid interaction plays a major role in controlling surface and ground water ree signatures

sand veins and wedges in cold aeolian environments sedimentary structures formed by the progressive primary infilling of thermal contraction cracks with sand are termed primary sand veins and sand wedges in addition to simple vein or wedge shapes irregularities can be caused by sand veins branching from their sides and toes primary sand wedges form widely in sandy polar deserts locally in sandy areas of tundra and probably in seasonally frozen ground there are no unique criteria for distinguishing primary sand veins and wedges from sand veins and wedges of other origins identification of the former depends on the occurrence of distinctive features not always present and on evaluation of their lithofacies and palaeoenvironmental contexts care and caution are advocated in the use of ancient relict primary sand veins and wedges as quantitative palaeoenvironmental indicators because modern active wedge distribution is poorly known and hence inferred thermal climatic threshold values are questionable it is suggested that ancient relict primary sand wedges exceeding 2 m in depth and with well developed vertical lamination probably indicate the former occurrence of continuous permafrost whereas sand veins and narrow sand wedges frost cracks are potentially ambiguous as they may form not only in the active layer above and within continuous permafrost but also in seasonally frozen ground in non permafrost areas

the direction of ice wedge cracking in permafrost downward or upward field studies have been carried out along the western arctic coast of canada in an attempt to determine whether all ice wedge cracks originate at the ground surface and therefore propagate downward or whether some cracks originate near the top of permafrost and then propagate both upward and downward the field studies have been concentrated upon 1 low and high centred tundra polygons a few thousand years old and 2 ice wedges growing for the first time on the bottom of a lake experimentally drained in 1978 the field instrumentation has included electronic crack direction indicators electronic elapsed timers and continuous temperature measurements the field studies reveal that many of the ice wedge cracks originated near the top of permafrost and then propagated upward to the ground surface as well as downward into ice wedge ice for the 1974 1982 period the field observations showed that about 57 of the ice wedges cracked from the ground surface downward and 43 cracked both upward and downw

geochemistry of the rare earth elements in hypersaline and dilute acidic natural terrestrial waters complexation behavior and middle rare earth element enrichments rare earth element ree speciation was modelled in acid 2 9 ph 3 5 hypersaline groundwaters from australia and from the palo duro basin in texas usa using a combined specific ion interaction pitzer model and ion pairing model the free metal ion species i e ln3 is the dominant form of dissolved rees in these systems accounting for 40 70 of the dissolved metal in groundwater from lake tyrrell victoria australia 50 90 of the rees in groundwater from lake gilmore western australia and always 90 of each ree in the texas groundwaters lakes tyrrell and gilmore are actually dry lakes that act as groundwater discharge zones the abundance of the free metal ion species increases in these waters with increasing ionic strength and with decreasing ph the free metal ion species is followed in abundance by ree sulfate and ree chloride complexes that account for 20 50 and 10 15 respectively of the dissolved rees in the groundwaters from lake tyrrell 15 30 and 5 20 respectively in the groundwaters from lake gilmore and 3 and 7 respectively in the palo duro basin groundwaters the groundwaters of the lake tyrrell system and the palo duro basin are enriched in the middle rees mrees compared to both the light rees lrees and the heavy rees hrees only nd sm and dy were determined in the lake gilmore groundwaters and consequently it is unclear whether these acid groundwaters are also enriched in the mrees previous investigators suggested that fe rich organic flocs ree phosphate complexation and solid liquid exchange reactions between terrestrial waters and mree enriched surface fe mn coatings suspended particulates or secondary mineral phases within aquifer materials may promote the development of mree enrichments in natural waters we propose that organic colloids and ree phosphate complexes are insignificant in acidic natural waters in regards to mree enrichments instead solid liquid exchange reactions or dissolution of surface coatings suspended particulates and or secondary phases as well as sulfate complexation more likely controls the development of mree enrichments in acidic natural terrestrial waters

new bioclimatic models for the quaternary palaearctic based on insectivore and rodent communities mammal remains preserved in archaeological and palaeontological deposits are commonly used to reconstruct past terrestrial climates and environments here we propose new species specific models for bioclimatic analysis a palaeoclimatic method based on a climatic restriction index for each mammal species discriminant analysis and multiple linear regressions our new models are based on small mammal associations particularly insectivores and rodents from quaternary paleoarctic contexts a dataset including new localities and an updated taxonomy was constructed in order to develop two approaches the first using only rodentia the second based on associations including both rodentia and eulipotyphla both approaches proved to be reliable for inferring both climate zone and quantifying temperature precipitation and seasonality rarefaction analysis revealed these new models to be reliable even when a substantial percentage of species from the original palaeocommunity was absent from the fossil site application of these new models to small mammal associations from two sequences balma de l abeurador france and el miron spain spanning from the last glacial maximum to the holocene are consistent with the primary climatic changes recorded by regional pyrenean proxies and showed an increase in mean annual temperature of between 3 and 5 c

light rare earth elements enrichment in an acidic mine lake lusatia germany abstract the distribution of rare earth elements ree was investigated in the acidic waters lake and groundwater of a lignite mining district germany the fe and so4 rich lake water ph 2 7 displays high ree contents e g la 70 g l ce 160 g l and an enrichment of light ree lree in the nasc normalised pattern considering the hydrodynamic model and geochemical data the lake water composition may be calculated as a mixture of inflowing quaternary and mining dump groundwaters the groundwater of the dump aquifer is lree enriched nevertheless the leachates of dump sediments generally have low ree contents and display flat nasc normalised patterns however geochemical differences and ree pattern in undisturbed lignite lree enriched pattern and low water soluble ree contents and the weathered lignite of the dumps flat ree pattern and high water soluble ree contents suggest that lignite is probably the main ree source rock for the lake water

rare earth element concentrations and speciation in organic rich blackwaters of the great dismal swamp virginia usa concentrations of rare earth elements ree major inorganic solutes and dissolved organic carbon doc were measured in waters from the great dismal swamp in southeastern virginia including lake drummond ph 4 3 and its principal surface inflows and outflow concentrations of ree are high in the lake average nd 8 nmol kg and the acidic doc rich inflow and out flow waters i e nd 12 5 nmol kg in jericho washington ditch and 8 nmol kg in feeder ditch respectively the slightly acidic ph 6 6 4 inflow waters from west of the suffolk scarp that comprise the chief source of surface water flow into lake drummond exhibit lower ree concentrations nd 3 4 7 nmol kg great dismal swamp waters are all enriched in the middle rees compared to the light and heavy rees lree and hree when normalized to upper continental crustal ucc values rare earths are positively correlated to doc concentrations in great dismal swamp waters and inversely correlated with ph speciation calculations using a modified version of the well established humic ion binding model v predict that organic matter complexes are the predominant form of dissolved rees in great dismal swamp waters despite significant competition from aqueous fe and al for organic matter binding sites adsorptive cathodic stripping voltammetry acsv was employed using a previously developed competitive ligand equilibration approach that involved adding the o cresolphthalexon ocp ligand to directly investigate ree complexation with natural organic ligands in great dismal swamp waters although preliminary the results of the acs voltammetric titrations are consistent with dominance of organic matter complexes of rees in great dismal swamp waters the results of the speciation modeling and the voltammetric titrations all point towards control of dissolved rees in great dismal swamp waters by complexation of these heavy metals with natural organic matter

hydrogeochemistry and rare earth element behavior in a volcanically acidified watershed in patagonia argentina abstract the rio agrio watershed in northern patagonia argentina is naturally acidic due to discharges of volcanic h 2 so 4 hcl and hf at its headwaters near the summit of copahue volcano a suite of water samples was collected from the summit of the volcano to a point roughly 40 km downstream where the ph of the rio agrio rose above 6 0 this suite included a sample of the hyperacidic ph the concentrations of ree in the rio agrio decreased by several orders of magnitude through the study area as a result of dilution and chemical attenuation a subtle shift in the slope of shale normalized profiles of dissolved ree concentration was observed from being weakly positive near the source of the rio agrio to showing a weak middle ree enrichment trend in lake caviahue to being weakly negative in the lower reaches of the river the trend to a negative slope across the lanthanide series in the lower river is explained by selective partitioning of the heavier ree to hydrous oxides of fe and al suspended in the water column and accumulating on the riverbed most of the decrease in ree load occurred immediately downstream of the confluence with a tributary that increased the ph of the rio agrio from 4 3 to 6 1 although the mixed water was supersaturated with ree phosphate compounds precipitation of lnpo 4 is not believed to have been a dominant process because the predicted pattern of inter element fractionation from phosphate deposition is inconsistent with the observed trends instead ree attenuation most likely occurred from adsorption onto freshly precipitated hydrous aluminum oxide the behavior of ree in the rio agrio watershed is broadly similar to what has been observed in watersheds that owe their acidity to oxidation of sulfide minerals

late miocene early pliocene climatic evolution of the granada basin southern spain deduced from the paleoecology of the micromammal associations this paper analyses the relationship between the evolution of the late miocene and early pliocene rodent and insectivore assemblages from the granada basin southern spain and climate changes these climatic changes in terms of humidity and temperature fluctuations are inferred from variations of the relative abundances of taxons with definite ecological preferences there is a general tendency towards a temperature increase from the latest tortonian middle turolian to the messinian late turolian and towards a decrease from the mio pliocene boundary latest turolian earliest ruscinian to the end of the zanclean late ruscinian dry conditions predominate in the latest tortonian middle turolian at the beginning of the messinian late turolian there was a significant increase in humidity followed by an aridification throughout the end of the messinian and zanclean late turolian and ruscinian these climatic variations are in accordance with the sedimentary evolution of the basin and agree with the climatic interpretations inferred from the shallow marine carbonate sediments temperate tropical deposited in the marine basins of southeastern spain during the studied time interval

temporal variations in the fractionation of the rare earth elements in a boreal river the role of colloidal particles rare earth element ree data from weekly sampling of the filtered 0 45 m and suspended particulate phase during 18 months in the kalix river northern sweden are presented together with data on colloidal particles and the solution fraction 3 kda the filtered ree concentration show large seasonal and temporal variations in the river lanthanum varied between approximately 300 and 2100 pm high ree concentration in the filter passing fraction is related to increased water discharge and there is a strong correlation between the ree concentration organic carbon al and fe physical erosion of detrital particles plays a minor role for the yearly transport of particulate ree in this boreal river system the suspended particulate fraction which is dominated by non detrital fractions accounted for only 35 of the yearly total transport of la in the river approximately 10 of the ree were transported in detrital particles during winter at spring flood in may about 30 of the lree and up to 60 of the hree where hosted in detrital particles ultrafiltration of river water during spring flood shows that colloidal particles dominate the transport of filter passing ree less than 5 of the filtered ree are found in the fraction smaller than 3 kda the colloidal fraction shows a flat to slightly lree enriched pattern whereas the solution fraction 3 kda show an hree enriched pattern compared with till in the catchment suspended particles show a lree enriched pattern data indicate that the ree are associated with two phases in the colloidal and particulate fraction an organic rich phase with associated al fe and an fe rich fe oxyhydroxide inorganic phase the ce anomaly in the suspended particulate fraction in the river shows systematic variations and can be used to interpret fractionation processes of the ree during weathering and transport there was no anomaly at maximum spring flood but during the ice covered period the anomaly became more and more negative the temporal and seasonal variations of the ce anomaly in the suspended particulate phase reflect transport of ree c al fe enriched colloids from the upper section of the till and or from mires to the river at storm events

orbital and sub orbital scale climate impacts on vegetation of the western mediterranean basin over the last 48 000 yr article i nfo high resolution pollen analysis of alboran sea core md95 2043 provides a 48 ka continuous vegetation record that can be directly correlated with sea surface and deep water changes the reliability of this record is supported by comparison with that of padul sierra nevada spain marine isotope stage mis 3 was characterised by fluctuations in quercus forest cover in response to dansgaard oeschger climate variability mis 2 was characterised by the dominance of semi desert vegetation despite overall dry and cold conditions during mis 2 heinrich events hes 2 and 1 were distinguished from the last glacial maximum by more intensely arid conditions taxon specific vegetation responses to a tripartite climatic structure within the hes are observed in mis 1 the bolling allerod was marked by rapid afforestation while a re expansion of semi desert environments occurred during the younger dryas the maximum development of mixed quercus forest occurred between 11 7 and 5 4 cal ka bp with forest decline since 5 4 cal ka bp on orbital timescales a long term expansion of semi desert vegetation from mis 3 into mis 2 reflects global ice volume trends while holocene arboreal decline reflects summer insolation decrease the influence of precession on the amplitude of forest development and vegetation composition is also detected

mineralogical control of rare earth elements in acid sulfate soils abstract major trace and rare earth element concentrations were measured in porewater surface water and sediments at an acid sulfate soil site the concentrations of la and ce in porewater are up to 1 3 ppm there is a strong correlation between ree concentration and acidity except that the maximum concentrations were consistently found below the horizon of maximum acidity associated with an increase in ph to ca 4 and change in mineralogy from jarosite dominated to goethite dominated mottles jarosite replacement by goethite is as expected with the rise in ph which in turn is due to the occurrence of a fossil shell bed just below the rare earth element patterns in the porewaters are enriched in the mree with respect to post archaean australian shale paas measurements and calculations show that this is in accord with experiments on low degree partial dissolution of jarosite even when the jarosite itself is highly enriched in lree there is a clear fractionation in the patterns between the clay rich soil matrix which is slightly depleted in the lree when normalized to paas la ybpaas 0 5 and the secondary mineral phase jarosite which is enriched in the lree la ybpaas 15 50 the ree pattern in the porewater changes with the transition from jarosite to goethite rich mottles becoming relatively more enriched in the lree compared to the hree which is consistent with the incongruent dissolution of jarosite to form goethite and the release of greater amounts of jarosite ree to solution including proportionately more of the jarosite compatible lree maximum surface water ree concentrations in acidic water were 100 200 ppb la and ce ree patterns in surface water were very similar to the porewater transition zone enriched in the mree but asymmetric relatively enriched in the lree compared to the hree

upper soil horizons control the rare earth element patterns in shallow groundwater several studies dedicated to the aquatic geochemistry of rare earth elements rees have displayed a wide topography related spatial variability in the ree signatures of shallow groundwater the aim of this study was to understand the processes leading to this specific ree signature notably with regard to the size of the ce anomaly soils were sampled in order to encompass the expected topographic variability in the organic carbon oc fe mn ratio leaching experiments were performed with the uppermost horizons of the soil the ree patterns that developed in the soil leaching solution were similar to the ree patterns for the shallow groundwater collected in this catchment the negative ce anomaly evolves in a similar manner according to the topography this spatial variation is strongly correlated with the soil oc fe ratio for a low oc fe ratio the negative ce anomaly amplitude in the soil solution is large whereas a high oc fe ratio generates a small or insignificant ce anomaly reductive dissolution experiments using soil with low oc fe ratios demonstrated that the ree pattern for soil fe oxyhydroxides exhibited a positive ce anomaly and hree enrichment indicating a preferential association of these elements with fe oxyhydroxides the rare earth element signature observed in the shallow groundwater is affected by fe oxyhydroxides present in the upper soil horizons in contrast in soil with a high oc fe ratio the ree pattern obtained under reducing conditions did not exhibit any ce anomaly suggesting that in the bottomland the ree signature is affected by the oc content in the uppermost soil this study highlights the impact of organic matter on the fe pedofeatures which control the development of a negative ce anomaly in shallow groundwater

the rare earth element geochemistry of acid sulphate and acid sulphate chloride geothermal systems from yellowstone national park wyoming usa rare earth element ree concentrations have been determined by inductively coupled plasma mass spectrometry icp ms in acid sulphate and acid sulphate chloride waters and the associated sinters and volcanic rocks from the yellowstone national park ynp wyoming usa geothermal system ree concentrations in the volcanic rocks range from 222 to 347 ppm their chondite normalised ree patterns are typical of upper continental crust with lree hree and negative eu anomalies total ree concentrations in the fluids range from 3 to 1133 nmol kg 1 162 ppm and ree concentrations in sinter are 181 ppm ree abundances and patterns in drill core material from ynp indicate some ree mobility normalisation of ree concentrations in altered lava creek tuff lct from y 12 drill core to ree concentrations in fresh lct indicate that the ree overall have been depleted with the exception of eu which has been decoupled from the ree series and concentrated in the altered rocks relative to the host rocks the ree patterns of the fluids are variably depleted in hrees and lrees and usually have a pronounced positive eu anomaly this decoupling of eu from the ree suite suggests that 1 eu has been preferentially removed either from the host rock glass or from the host rock minerals or 2 the waters are from a high temperature or reducing environment where eu2 is more soluble than the trivalent rees since the latter is inconsistent with production of acid sulphate springs in a low temperature oxidising near surface environment we suggest that the positive eu anomalies in the fluids result from preferential dissolution of a eu rich phase in the host rock spatial and temporal variations in major element chemistry and ph of the springs sampled from norris geyser basin and crater hills accompany variations in ree concentrations and patterns of individual geothermal springs these are possibly related to changes in subsurface plumbing which results in variations in mixing and dilution of the geothermal fluids and may have lead to changes in the extent and nature of ree complexing

rare earth element mineralogy and geochemistry in a laterite profile from madagascar abstract in this study rare earth element ree distribution has been investigated in a weathering profile from central madagascar combination of bulk rock geochemical data elements and isotopes with mineral characterization reveals a remarkable evolution of the ree abundances and ree minerals in the vertical weathering profile in the fresh tonalite bedrock ree y concentrations are typical of granitoids 299 363 ppm and the main ree minerals are allanite and chevkinite in the c horizon saprolite primary ree minerals disappear and rees are transported via fluid to precipitate rhabdophane group minerals in cracks and pores the presence of sulfate ligands produced by sulfide oxidation may be responsible for the ree speciation as suggested by the composition of the secondary ree minerals rhabdophane group minerals contain up to 9 wt so 3 and 7 wt cao indicating a mixture between rhabdophane sensu stricto ree po 4 h 2 o and tristamite ca u fe iii po 4 so 4 2h 2 o due to intense ca leaching rhabdophane disappears and al phosphates alunite jarosite group are found in the soil cerianite ce iv o 2 also precipitates in the b horizon of the soil mass transfer calculations based on immobile ti indicate significant ree leaching in a horizon with preferential leaching of the heavy ree rees accumulate partly in the b horizon the uniform nd isotope compositions and the constant proportion of immobile elements do not reveal external input in the b horizon total ree y reach 2194 ppm with high ce concentrations 1638 ppm 9 ce bedrock compared to other ree 3 4 ree bedrock tetravalent ce state is dominant in the b horizon and requires oxidizing conditions that likely account for the accumulation of redox sensitive elements in b horizon e g mn fe co under oxidizing conditions cerianite precipitation causes a ce fractionation from other trivalent ree in comparison to the ion adsorption clay of southern china preferential heavy ree enrichment was not observed in the weathering profile another remarkable peculiarity of the studied profile is the occurrence of gd 2 so 6 grains the discovery of this new mineral demonstrates that a natural process exists that that can fractionate ree to such an extent to produce a pure gadolinium end member mineral an understanding of such a mechanisms is crucial for the ree geochemistry of low temperature alteration processes as well as for the formation of ree ore deposits or industrial processing

multiple implications of rare earth elements for holocene environmental changes in nam co tibet abstract rare earth elements rees from a 332 cm long core surface sediments and soils of the lake shores were examined with the aim of evaluating their suitability as a paleo environmental proxy rees were transported into the nam co lake not only by runoff but also by wind concentrations of ree in the core range from 97 57 to 162 98 ppm with an average of 126 5 ppm from 171 3 to 475 7 ppm in the soils of shores and from 65 03 to 354 03 ppm in the surface sediments with an average of 130 64 ppm the ree average of soils is 158 9 ppm for the northern shore 214 72 ppm for the southern shore 244 ppm for the eastern shore and 289 69 ppm for the western shore the ree average of surface sediments is 114 45 ppm for the northern lake 115 73 ppm for the eastern lake 129 69 ppm for the western lake 144 38 ppm for the southern lake and 150 95 ppm in the center of the lake suggesting an accumulation of rees in the center of the lake the ratios of lree hree range from 8 to 11 85 for the core from 7 8 to 11 8 for the surface sediments and from 6 5 to 14 5 for the soils which suggesting that lree are richer than hree the ree distribution patterns of all samples are characterized by v shape curves with slightly negative ce anomalies from 0 83 to 0 99 and obviously negative eu anomalies from 0 28 to 0 72 mn played an active role on the ce anomaly the values of ce showed almost no variance suggesting a stable post depositional environment in the core the rees peaks of 140 ppm occurred at 6 9 ka 307 cm 5 9 5 5 ka 292 287 cm 2 2 2 0 ka 262 252 cm and 1 78 ka 212 cm corresponding to the beginning of environmental shifts and or events while the rees peak at 0 91 0 87 ka 107 102 cm and the rees valley of

genesis of ree minerals in the karstic bauxite in western guangxi china and its constraints on the deposit formation conditions abstract karstic bauxites in western guangxi china comprise two subtypes permian bauxite and quaternary bauxite the quaternary bauxite originated from the breaking up rolling and accumulating of permian bauxite in karstic depressions in quaternary various types of rare earth element ree minerals were discovered during the formation of the permian and quaternary bauxites from the xinxu longhe and tianyang bauxite deposits in this study five types of ree minerals including bastnasite parisite cerianite rhabdophane and churchite were identified bastnasite and parisite are the most abundant and they are widely developed in the permian ore and also present in the quaternary ore obvious variations in bastnasite and parisite ree compositions were observed which is ascribed to distinctions in the source materials in the primary weathering profile from different areas the mode of occurrence of bastnasite and parisite suggests they were mainly precipitated under alkaline and reducing conditions during the permian bauxite forming stage and underwent intensive corrosion in the quaternary churchite was formed during the permian weathering stage under acidic condition both cerianite and rhabdophane occur in fractures within the permian bauxite ore indicating that both formed during the quaternary weathering stage it is considered that the rhabdophane enriched in ce have formed locally in the process of that the ce3 released from bastnasite rapidly entered the rhabdophane lattice before being oxidized to ce4 cerianite was mainly found in association with mn al hydroxides suggesting that the released ce3 was oxidized into ce4 and precipitated cerianite in fractures within the permian bauxite ore mass balance equations reveal a depletion in nearly all rees during the transformation from the permian to the quaternary bauxite ore mainly caused by the dissolution of bastnasite and parisite the genesis of the ree minerals together with the occurrence of other minerals indicates that intensively acidic and oxidizing conditions developed before the formation of the permian bauxite ore towards the end of the permian the conditions became reducing and alkaline favorable for the large scale bauxitization the quaternary bauxite forming stage was characterized by variable ph and eh conditions with acidic ph 4 6 and oxidizing eh 2 conditions at the surface of the exposed permian bauxite ore

jarosites and their application in hydrometallurgy the alunite supergroup consists of more than 40 minerals with the general formula dg 3 t o4 2 oh h2o 6 wherein d represents cations with a coordination number greater or equal to 9 and g and t represent sites with octahedral and tetrahedral coordination respectively smith et al 1998 the supergroup is commonly subdivided into various groups but the simplest primary subdivision is on the basis of the g cations for all of the minerals in the supergroup the dominant g cation is trivalent most of the minerals have g represented by fe3 or al3 but exceptions are the rare minerals gallobeudantite in which g is ga3 and springcreekite in which g is v3 table 1 thus the primary grouping adopted here is on whether formula fe3 exceeds or is subordinate to al3 the hierarchical sequence in mineralogy seems to be variable but here the decreasing sequence is given as supergroup family group and subgroup minerals with fe3 al3 are referred to as belonging to the jarosite family and those with a13 fe3 are allocated to the alunite family view this table table 1 minerals of the alunite supergroup subdivision of the alunite and jarosite families has also been variable scott 1987 for example used seven groups novak et al 1994 used six gaines et al 1997 used four and mandarino 1999 used three the arbitrary decision here is to use three groups which differ from those of mandarino 1999 but which in general indicate whether sulfate phosphate or arsenate predominates in the t o4 tetrahedra the three groups are the alunite group in which t o4 is dominated by so4 the crandallite group in which po4 is

geochemistry of the rare earth elements and uranium in the acidic berkeley pit lake butte montana abstract filtered 0 45 m and nonfiltered concentrations of rare earth elements ree u zr th ba sc and y were measured as a function of depth in the berkeley pit lake a large acidic mining lake in butte mt the ree show very little variation with depth apart from a slight concentration near the surface presumably due to evaporation the ree profiles of the pit waters show a depletion in light ree when normalized against nasc and the host butte quartz monzonite bqm and a possible enrichment in middle ree vs heavy ree when normalized against bqm all of the ree partitioned weakly into secondary ferric precipitates formed by aging of deep berkeley pit water the measured distribution coefficients increased across the lanthanide series from la kd 7 7 to nd kd 10 3 and then decreased steadily to lu kd 1 4 under the conditions of the berkeley pit lake the aqueous speciation of ree and u is dominated by sulfate complexes because the stability constants of ree sulfate complexes show very little variation across the lanthanide series the observed trends in kd cannot be explained by aqueous complexation despite high concentrations of dissolved ree e g 1 1 mg l ce and u 0 85 mg l saturation indices for all solid phases were strongly negative due to the low ph of the berkeley pit lake 2 3 2 6 the mobility of ree and u is more likely constrained by adsorption or co precipitation with strengite jarosite schwertmannite or other secondary minerals forming in the lake

adsorption of rees on kaolinite and halloysite a link to the ree distribution on clays in the weathering crust of granite abstract the clay minerals kaolinite and halloysite are dominant hosts for rare earth elements rees in the weathered crust elution deposited ree deposits however the accumulation of rees on kaolinite and halloysite has not been systematically compared in this study the adsorption of complete ree series on kaolinite and halloysite was investigated under different ph levels and ionic strengths which was linked to the enrichment and fractionation of rees within the clay fraction of a typical weathered crust elution deposited ree deposit at low ionic strength the adsorption of rees on kaolinite and halloysite increased with increase in ph with some noticeable fluctuation observed on halloysite at high ph all the rees were adsorbed to a similar extent without apparent fractionation except for the slight enrichment of heavy rees hrees at high ph at high ionic strength ree adsorption exhibited a linear increase with the increase in ph particularly at high ph with hrees being preferentially adsorbed compared to halloysite kaolinite possessed a higher specific surface area ssa normalized adsorption capacity towards rees these observed adsorption characteristics could possibly explain the distribution of rees in the clay fraction along the ree deposit the decrease of ion exchangeable ree content with depth was significant for kaolinite while the ree fractionation was ascribed to the selective adsorption of hrees on both kaolinite and halloysite the enrichment and fractionation mechanism of rees on kaolinite and halloysite were also discussed in terms of the surface chemistry and morphology of the clay minerals and the variations of chemical properties across the ree group

icelandic permafrost dynamics since the last glacial maximum model results and geomorphological implications abstract iceland s periglacial realm is one of the most dynamic on the planet with active geomorphological processes and high weathering rates of young bedrock resulting in high sediment yields and ongoing mass movement permafrost is discontinuous in iceland s highlands and mountains over c 800 m a s l and sporadic in palsa mires in the central highlands during the late pleistocene and holocene iceland s periglacial environment varied considerably in time and space dominated by glacial fluctuations and periglacial processes to evaluate the dynamics of permafrost in iceland since the last deglaciation we use the output of a coupled climate ice sheet model to force a transient permafrost model cryogrid 2 from the last glacial maximum lgm through to the present we find that permafrost was widespread across the deglaciated areas of western northern and eastern iceland after the lgm and that up to 20 of iceland s terrestrial area was underlain by permafrost throughout the late pleistocene this influenced geomorphological processes and landform generation the early collapse of the marine based ice sheet together with the aggradation of permafrost in these zones initiated the formation of abundant and now relict rock glaciers across coastal margins permafrost degraded rapidly after the younger dryas with a marked impact on slope stability permafrost that formed during the little ice age is again thawing rapidly and an escalation in slope failure and mass movement might be currently underway our study demonstrates that large regions of iceland have been underlain by permafrost for millennia facilitating landform development and influencing the stability of steep slopes

assessing the impact of serwis mine tailings site on farmers wells using element and isotope signatures holy cross mountains south central poland this paper presents the results of a geochemical and isotopic study of technogenic soils and acid pool waters in the abandoned mine tailings pile and its potential impact on the adjacent farmers wells at the village of serwis south central poland the acid tailings pools showed strong trace element and ree signals these acid pools were featured by the predominance of medium rare earth elements mree with a strong positive gd anomaly the technogenic soils also revealed a mree roof shaped pattern but with distinct positive excursions in gd sm eu and ce the 34s so42 signatures of acid pool waters mean of 1 3 were close to those of soils and pyrite means of 2 3 and 3 2 respectively the waters of four farmers wells exhibited nearly the same 34s so42 values 0 7 4 0 as the nearby acid pool waters 0 3 3 1 the similar 34s isotope signatures combined with the highest contents of dissolved so42 181 577 mg l in these wells suggest that the tailings pile is a potential source of so42 derived from pyrite weathering this relationship may also be evidenced by a spatial site variable dendrogram that groups these four wells into one cluster at the linkage distance dlink dmax 100 53

geographic and temporal patterns in the late neogene 12 3 ma aridification of europe the use of small mammals as paleoprecipitation proxies abstract present day relations between small mammal community structure and rainfall are used to predict late neogene 12 3 ma precipitation patterns in europe and anatolia new proxy methods are developed which include regressions of mean annual and minimum monthly precipitation on diet invertivory index and locomotion habitat arboreality index a series of precipitation maps and a set of regional precipitation curves through time at 1 myr resolution are presented precipitation curves at a higher temporal resolution are constructed for the region of central spain the miocene results show the existence between 12 and 9 ma of a large wet 800 1200 mm yr zone extending from northern spain to the ukraine and characterized by the whole year penetration of large amounts of moisture far into the continent between 10 9 and 5 ma this european temperate wet zone etwz shrinks and or moves northward resulting in diachronous aridification a coeval northward migration of the subtropical high pressure zone shpz is hypothesized which is also consistent with the predicted onset of seasonal summer dryness between 10 and 8 ma the maximum extension of the etwz at 12 9 ma temporally correlates with northern hemisphere cooling suggesting that climate zonation rather than the global amount of atmospheric moisture controlled european climate at this time the main aridification at 9 8 ma could best be explained by a northward extension shifting of the subtropical high pressure zone and a transition towards less zonal circulation processes which ultimately could have been triggered by uplift of the tibetan plateau a temporary increase of precipitation at 7 6 ma is associated with renewed global cooling the lowest precipitation values less than 400 mm yr occur during the pliocene in southern and eastern europe uplift in eastern europe carpathians shrinking of the paratethys could well explain the aridification in this area and the associated sharpening of east west precipitation gradients across the continent

low altitude remote sensing and gis based analysis of cropmarks classification of past thermal contraction crack polygons in central western poland abstract the examination of low altitude aerial photographs reveals the presence of more than 400 polygonal nets in central western poland polygons range from 5 to almost 70 m in diameter based on the polygons diameter and intersection angles we identified seven main types of nets geometry based on ground verification we interpreted them as past thermal contraction cracks filled mostly with sand i e sand wedge casts as favourable weather conditions and a proper land cover i e cultivated land are necessary for identifying polygonal nets the observed number of polygons is probably much underestimated the broad occurrence of former thermal contraction cracks polygons indicates that continuous permafrost was widespread in central western poland after the termination of the last glacial maximum lgm preliminary dating of the cracks infilling as well as polygon geometry suggest that thermal contraction cracking occurred in several different phases and that a time frame of a few thousand years is sufficient to form complex mature nets

clay minerals of late pleistocene sites jonzac and les cottes sw france applications of x ray diffraction analyses to local paleoclimatic and paleoenvironmental reconstructions abstract the crystal chemical properties of clay minerals are closely dependent on the physicochemical conditions prevailing at the time when they formed in soils and weathered zones the degree of alteration of primary minerals and the composition of the secondary products are clearly linked to climate and plant cover in particular changes are rapid under temperate conditions which favor the development of thick soils but slow in cold contexts favoring thin and fragile soils in this paper the mineral composition of two pleistocene clay rich deposits is investigated in order to contribute to reconstructing paleoenvironmental changes jonzac charentes sw france and les cottes vienne sw france are two rock shelters with long archaeological sequences which include faunal remains and were recently radiometrically dated the decomposition of xrd patterns at each site allows identification of the principal mineral phases and semi quantitative estimation of their relative proportions the variation of these proportions is analyzed through indexes based on the relative intensities of the decomposed bands the clay fraction of both sites mostly results from the transformation of the minerals forming the sediments in the surrounding area of the rock shelter terrace including contributions from the hillside mineralogical clay data are compared with the faunal spectrum identified at both sites in order to discuss paleoenvironmental implications at jonzac during the quina mousterian period dated to mis4 the environment was cold and dry the dominant mineralogical phases are inherited from the rocks weak pedogenesis this is consistent with the faunal analysis data typical of the mis4 during the mousterian of acheulean tradition period dated to mis3 the mineralogical composition of the clay deposits changed significantly suggesting a less wet environment the aurignacian deposits dated to the end of mis3 early mis2 are rich in mixed layer minerals mlms which are produced by the hydrolysis processes in soils the climatic conditions probably became milder however because no faunal remains were found this evolution is uncertain the les cottes deposits dated between mis3 and early mis2 are mineralogically typical of a cold environment where soil reactions are not very active however some weak variations of the indexes suggest temporary temperate conditions during the les cottes interstadial and in the aurignacian the parallelism between mineral signature and paleontological evidence in recording relatively rapid variations between contrasted climates suggests that clay mineral assemblages from rock shelter deposits can be used to assess paleoclimatic and paleoenvironmental dynamics at a local scale

rapid development of negative ce anomalies in surface waters and contrasting ree patterns in groundwaters associated with zn pb massive sulphide deposits ground and surface waters collected from two undisturbed zn pb massive sulphide deposits the halfmile lake and restigouche deposits and active mines in the bathurst mining camp bmc nb canada were analysed for the rare earth elements ree ree contents are highly variable in waters of the bmc with higher contents typical of waters with higher fe and lower ph there are significant differences between ground and surface waters and between groundwaters from different deposits the ree contents of surface waters are broadly similar within and between deposit areas although there are spatial variations reflecting differences in ph and redox conditions surface waters are characterised by strong negative ce anomalies ce ce nasc as low as 0 08 produced by oxidation of ce3 to ce4 and preferential removal of ce4 from solution upon leaving the shallow groundwater environment groundwaters and seeps typically lack significant ce anomalies reflecting generally more reducing conditions in the subsurface environment and indicating that ce oxidation is a rapid process in the surface waters deeper groundwaters at the halfmile lake deposit are characterised by ree patterns that are similar to the host lithologies whereas most groundwaters at the restigouche deposit have lree depleted patterns compared to nasc halfmile lake deposit groundwaters have generally lower ph values whereas restigouche deposit groundwaters show greater heavy ree complexation by carbonate ions shallow waters at the halfmile lake and stratmat main zone deposits have unusual patterns which reflect either the adsorption of light ree onto colloids and fracture zone minerals and or precipitation of ree phosphate minerals middle ree enrichment is typical for ground and surface waters and is highest for neutral ph waters the labile portion of stream sediments are generally more middle ree enriched than total sediment and surface waters indicating that the ree are removed from solution by adsorption to fe and mn oxyhydroxides in the order middle ree light ree heavy ree

water rock interaction in an acidic mine discharge as indicated by rare earth element patterns abstract the rare earth element ree composition of an acidic spring discharging at ph 2 7 was studied in relation to the ree composition of selected extracts of the coal bearing strata hydrologically above the discharge the low ph of the discharge and the access to the strata through which it flows provides an excellent opportunity to study the use of rees as tracers of water rock interaction extraction techniques were used to mimic the process of acidic groundwater generation in coal bearing strata samples were treated to remove exchangeable ions and then treated sequentially with solutions buffered at ph 5 5 3 6 and 1 6 in order to mimic the natural buffering systems of groundwaters finally samples were oxidised with hydrogen peroxide in an attempt to remove the pyrite the results show that the composition of the spring is controlled by pyrite oxidation and buffering by fe oxy hydroxides the latter with compositions inherited from carbonates from within the sequence the similarity of ree patterns of the carbonate and the silicate extracts tends to obscure information concerning the relative roles of carbonate or silicate phases the source strata of the spring has evolved over time and shows that different coal seams have a unique contribution this distinct contribution appears more related to the mixture of sedimentary components i e carbonates silicates etc in the coal seam and the combination of shale and sandstone layers surrounding coal seams than the composition of the components themselves the similarity between ree compositions of the sequential extracts suggests that relationships discovered for this spring will be applicable elsewhere in the basin however this very property will hamper the use of such lithophilic elements in cases where characterisation of the source area is not possible

rare earth elements in pore waters of marine sediments abstract the rare earth elements rees were measured in pore waters of the upper 25 cm of sediment from one site off peru and three sites on the california margin the pore water ree concentrations are higher than sea water and show systematic down core variations in both concentration and normalized pattern from these analyses and from comparison to other chemical species measured dissolved fe mn ba oxygen nitrate phosphate it is suggested that pore water rees can be grouped into three categories those that are from an fe source those that are from a poc source and cerium oxide rees from the fe source appear where anoxia is reached they have a distinctive middle ree mree enriched pattern the concentrations in this source are so elevated that they dominate ree trends in the fe oxide reduction zone the net result of flux from the poc source is relative enrichment of heavy rees hrees over light rees lrees reflecting remineralizing poc and complexation with doc a common linear ree pattern seen in both oxic and anoxic sediments is associated with this poc source as well as a hree enriched pattern that is seen in surficial sediments at the peru site overall the pore water results indicate that mn oxides are not an important carrier of rees in the oceans a ree biogeochemical model is presented which attempts to reconcile ree behavior in the water and sediment columns of the oceans the model proposes that poc fe oxide and ce oxide sources can explain the ree concentration profiles and relative abundance patterns in environments ranging from oxic sea water to anoxic pore water the model is also consistent with our observation that the ce anomaly of pore water does not exceed unity under any redox condition

rare earth elements as a tool for studying the formation of cemented layers in an area affected by acid mine drainage abstract in a profile with two cemented layers sampled in an area affected by acid mine drainage both have rare earth element ree signatures with positive ce anomalies in the post archean australian shale normalised patterns both cemented layers have higher contents of environmentally relevant metals cd co cu fe mn u and zn than the over and underlying unconsolidated quaternary sediments and are depleted of al ca k and mg the cemented layers are enriched in middle and heavy ree but only the bulk pattern of the lower cemented layer reveals a positive ce anomaly for the upper cemented layer this positive ce anomaly was only determined by spatially resolved laser ablation inductively coupled plasma mass spectrometry la icp ms studies only for segments with a high abundance of mn occurring as mn phases as proven by energy dispersive x ray spectroscopy the mn phases are formed secondarily to the ferric cement and are especially enriched in ce and co the ce anomaly of the lower cemented layer most probably is inherited from groundwater to the ferric cement whereas the ce anomaly of the upper cemented layer is the result of preferential scavenging of ce onto the mn phases compared to other ree

microbial controls on phosphate and lanthanide distributions during granite weathering and soil formation abstract both microbial and geochemical factors control the form distribution and abundance of lanthanides during weathering and soil formation in a profile in the bemboka granodiorite from southern new south wales australia during the initial stages of weathering hydrous ce bearing lanthanide and lanthanide aluminum phosphates including rhabdophane and florencite crystallize on etched apatite surfaces throughout the profile however their fate depends greatly on their location within the profile in rocks weathered 5 6 m below the soil zone the lower profile secondary lanthanide phosphates persist long after all apatite has been dissolved however in rocks weathered within 2 m of the soil zone the upper profile secondary phosphates are dissolved and lanthanides other than ce are removed bacteria and fungal hyphae are localized on secondary phosphate surfaces suggesting that rhabdophane and florencite are solubilized in the upper profile due to organic complexation of dissolved lanthanides and or uptake of phosphate by cells in the soils defined by loss of granitic texture secondary phosphates are replaced by ce oxides lanthanides other than ce removed in solution from the upper profile precipitate as ce poor phosphates in the lower profile when the solubility product is exceeded due to high dissolved phosphate concentrations in proximity to apatite thus the upper profile is the source of lanthanides added to the lower profile in both the lower and upper weathered granite the degree to which weight based ce abundances increase with increasing weathering is consistent with ce immobility on the centimeter scale we attribute the very high weight based ce abundances up to 12 concentrations in fresh rock to extensive leaching and compaction during transformation of weathered rock to soil

δ18o and ree contents of phosphatic brachiopods a comparison between modern and lower paleozoic populations 18o values of both carbonate 18 7 25 1 and phosphate 15 1 16 7 components of the francolite from the fossil brachiopod shells are interpreted as the result of a partial resetting of pristine isotopic compositions the similarity of hat shape ree patterns of some lower ordovician linguloids with those of extant littoral specimens suggests the preservation of a 500 myr old record of ree marine chemistry in agreement with the known paleogeography the phosphatic brachiopods have been deposited in a coastal environment under shallow and oxygenated marine waters however the contents and distribution of ree in some strongly altered brachiopod shells reveal an alteration of the original negative ce anomalies and both nd and sm enrichments that transformed the initial hat shape patterns of linguloids into strongly convex or bell shape patterns

rodents and climate a new model for estimating past temperatures based on the high correlation between species richness in sigmodontine rodents and temperatures we propose a new model in order to quantify past climates because of the close phylogenetic relationship and the tooth morphological similarity between extant new world cricetids sigmodontinae and fossil european cricetids cricetinae s l extant new world sigmodontines are taken as analogues for old world fossil cricetines sigmodontine species richness has been compiled for 282 extant local faunas from north central and south america with corresponding climatic data temperatures and precipitations there is almost no correlation between areas covered by local faunas ranging from 1 km2 up to 46 000 km2 and numbers of sigmodontine species in localities r2 0 027 number of sigmodontine species in local faunas and mean annual daily temperatures are highly correlated r2 0 88 the relationships of species richness and precipitation is low r2 0 19 for mean annual precipitation the method is exemplified for old world cricetines using well documented miocene rodent faunas located in the lyon area

ice wedge casts and relict polygonal patterns in scandinavia ice wedge casts in scandinavia frequently occur in three regions a southwestern jutland outside the limit of the weichselian glaciation b southwestern sweden and c northernmost norway the latter two areas are both early deglaciated regions characteristics of casts in vertical sections are discussed with reference to the host and infilling material aerial photographs provide an effective tool for detecting relict ice wedge polygons crop marks micromorphology experience from present day permafrost regions with active ice wedge formation helps to explain the palaeoclimatic significance of the relict polygons attempts to establish the ages of formation are discussed from a methodological point of view

oxygenation of acid sulfate soils stimulates co2 emission roles of acidic dissolution and hydroxyl radical oxidation abstract emission of co2 from acid sulfate soil regions has received great attention in recent years production of co2 due to microbial respiration has been documented by previous studies but the abiotic mechanisms are poorly understood in this study co2 production was measured from oxygenation of 60 acid sulfate soil samples that were collected from a typical acid sulfate soil region the soil samples were characterized by low ph 3 3 5 8 and high sulfate content 0 51 5 03 mg g the cumulative concentrations of co2 were 0 76 54 54 mol per g dry soil upon oxygenation for 24 h when 0 1 hgcl2 was added into soil suspension to kill microbes the yield of co2 decreased by 8 7 41 1 which suggests that both microbial respiration and abiotic pathways contributed to co2 production and abiotic pathway played a major role both acidic dissolution and hydroxyl radical oh oxidation were identified to be the abiotic mechanisms for co2 production for acidic dissolution co2 was produced from the decomposition of carbonate by h generated production of co2 from acidic dissolution was dependent on the content of carbonate and the generation of h a combination of fe speciation sequential extraction and kinetic model shows that h was mainly generated from the oxidation of both fe2 and pyrite by o2 for oh oxidation co2 was produced from the oxidation of organic carbon by oh produced and its relative importance for co2 production was estimated to be 14 6 27 6 oh was mainly produced from exchangeable fe ii oxidation in sulfuric horizon but from pyrite oxidation in potential acid sulfate soils this study presents the overlooked abiotic mechanisms acidic dissolution and oh oxidation for co2 emission in acid sulfate soils when perturbed by o2 our findings implicate that contribution of microbial respiration for co2 production is not as large as previously thought to be in acid sulfate soils and instead abiotic mechanisms contribute largely particularly for oxygenation of potential acid sulfate soils

environmental geochemistry of rare earth elements in cu porphyry mine tailings in the semiarid climate conditions of sarcheshmeh mine in southeastern iran abstract sarcheshmeh mine is one of the largest oligo miocene porphyry cu deposits in the world it is located in the kerman cenozoic magmatic arc in southeastern iran this paper discusses the geo environmental behavior of rare earth elements rees in the sarcheshmeh dammed tailing pond situated in semiarid climate for this purpose solid and water samples were collected to consider 1 weathering oxidation reactions and upward migration of soluble elements 2 super saturation and formation dissolution of the secondary evaporative phases 3 hydro geochemical changes of the surface and groundwater resources 4 flotation of the cu sulfide ore and tailing management strategies the mean values of the rees for fresh and weathered tailings and the evaporative phases were 113 0 103 7 and 74 6 mg kg respectively when compared with the fresh and weathered tailings the evaporative phases showed significant enrichment of hrees and a well depleted pattern of lrees except for that of eu this geochemical pattern suggests a higher solubility and mobility potential of hrees and eu compared with lrees resulting in good fractionation and enrichment of these elements in the surface evaporative layer formed on top of the weathered tailings the water samples showed a range of hydro geochemical features under acidic ph of 2 5 to 4 7 near neutral ph of 6 4 to 7 9 alkaline ph of 8 to 10 and highly alkaline ph 10 conditions the maximum concentration of rees was observed in the acidic waters produced by the weathered tailings after rainfall rees of 489 to 1903 g l although rees decreased as the ph value increased the general trend was compatible with the highest concentration of hrees rather than lrees the speciation calculations indicate that lnso4 ln so4 2 and ln3 are the primary forms of dissolved rees at acidic and near neutral ph and the dominant species was lnso4 lnco3 40 78 ln co3 2 31 68 and lnso4 31 07 were the dominant species under alkaline conditions at high alkaline ph the speciation pattern changed to lnoh2 53 15 ln co3 2 44 88 and lnco3 2 61 where ln denotes lanthanide based on the results and considering previous works it appears that ionic potential plays an important role in the geo environmental behavior of rees of adsorption tendency mobility potential and ionic substitution

sulfur biogeochemical cycling and novel fe s mineralization pathways in a tidally re flooded wetland abstract sulfur biogeochemical cycling and associated fe s mineralization processes exert a major influence over acidity dynamics electron flow and contaminant mobility in wetlands benthic sediments and groundwater systems while s biogeochemical cycling has been studied intensively in many environmental settings relatively little direct information exists on s cycling in formerly drained wetlands that have been remediated via tidal re flooding this study focuses on a tidal wetland that was drained in the 1970s causing severe soil and water acidification and subsequently remediated by controlled re flooding in 2002 we examine so 4 2 reduction rates and fe s mineralization at the tidal fringe 7 years after the commencement of re flooding the initial drainage of the wetland examined here caused in situ pyrite fes2 oxidation resulting in the drained soil layers being highly acidic and rich in so 4 2 bearing fe iii minerals including jarosite kfe3 so4 2 oh 6 tidal re flooding has neutralized much of the previous acidity with the pore water ph now mostly spanning ph 5 7 the fastest rates of in situ so 4 2 reduction up to 300 nmol cm 3 day 1 occur within the inter tidal zone in the near surface soil layers to 60 cm below ground surface the so 4 2 reduction rates correlate with pore water dissolved organic c concentrations thereby suggesting that electron donor supply was the predominant rate determining factor elemental s was a major short term product of so 4 2 reduction comprising up to 69 of reduced inorganic s in the near surface soil layers this enrichment in elemental s can be partly attributed to interactions between biogenic h2s and jarosite a process that also contributed to enrichment in pore water fe2 up to 55 mm and so 4 2 up to 50 mm the iron sulfide thiospinel greigite fe3s4 was abundant in near surface soil layers within the inter to sub tidal zone where tidal water level fluctuations created oscillatory redox conditions there was evidence for relatively rapid pyrite re formation within the re flooded soil layers however the results indicate that pyrite re formation has occurred mainly in the lower formerly drained soil layers whereas the accumulation of elemental s and greigite has been confined towards the soil surface the discovery that pyrite formation was spatially decoupled from that of elemental s and greigite challenges the concept that greigite is an essential precursor required for sedimentary pyrite formation in fact the results suggest that greigite and pyrite may represent distinct end points of divergent fe s mineralization pathways overall this study highlights novel aspects of fe s mineralization within tidal wetlands that have been drained and re flooded in contrast to normal undisturbed tidal wetlands as such the long term biogeochemical trajectory of drained and acidified wetlands that are remediated by tidal re flooding cannot be predicted from the well studied behaviour of normal tidal wetlands

the distribution of rare earth elements in groundwaters assessing the role of source rock composition redox changes and colloidal particles rare earth element ree dissolved organic carbon doc and trace element al mn fe sr ba u and th concentrations were measured in fourteen well water samples 0 22 m and one spring located along two transects set up in a catchment from western europe kervidy coet dan catchment france previous hydrological and hydrochemical no3 so42 investigations demonstrated that three chemically and spatially distinct groundwater types are present in this catchment which is fully confirmed by the ree and doc results these include i a shallow organic rich groundwater 4 4 doc 34 6 mg l from the wetland areas close to the river network this first groundwater type characterized by the development of temporary reducing conditions records high and variable ree contents 2 ree 16 ppb and displays slight or no negative ce anomaly ce ce 0 8 1 05 ii a shallow organic poor doc 3 mg l no3 rich groundwater type 86 8 no3 155 mg l located in the weathered schists below the hillslope domains this second type corresponds to recently recharged oxidized water and displays also high and variable ree concentrations 2 ppb ree 15 ppb but distinguish from the former by the occurrence of very strong negative ce anomalies ce ce 0 05 0 10 finally iii a deep organic poor doc 1 mg l nitrate poor no3 close to 0 2 mg l detection limit groundwater this third type corresponds to reduced water flowing into the deep fresh schists and yields low to very low ree contents ree 0 15 ppb as well as slight negative ce anomaly ce ce 0 8 to 0 9 temporal ree concentration variations were assessed using samples regularly collected over a six month period results show that the spatially distributed ce anomaly and ree pattern signatures are preserved throughout the studied period by contrast ree concentrations are quite variable through time especially in the wetland waters where the ree concentrations are seen to vary in phase with both redox changes and doc fe u and th content variations three ree rich water samples one doc rich and two doc poor were also filtered through membranes of decreasing pore size 100 000 d 30 000 d 5 000 d the results show that between about 40 to 65 of the ree present in the shallow doc poor groundwater samples are controlled by the colloidal fraction which is likely to consist in these inorganic waters of a mixture of mineral phases in the wetland groundwaters the fraction of ree controlled by microparticles is higher than 65 which confirms the predominant role of organic colloids as major ree carriers in wetland waters using the above data set in conjunction with analyses of soil samples we show that the deep ce anomalies found in the upper non organic part of the aquifer are probably not source rock inherited features most likely these anomalies arise from the oxidative precipitation of ce the very low ree content displayed by waters flooding the deep fresh schists is interpreted as due to the combined effects of i ph variation ii secondary sulfate mineral precipitation and iii the trapping of colloids borne ree by the aquifer rock pores data from wetland groundwaters show that the ree fe u and th budgets of these waters are mainly controlled by seasonal changes in redox conditions and organic matter content however unlike organic poor waters it appears difficult to relate the ce behaviour in these organic rich waters solely to redox conditions it is likely that the complexation of ce by organic colloids in the organic rich waters may mask redox changes by inhibiting the development of negative ce anomalies

do archean chemical sediments record ancient seawater rare earth element patterns rare earth elements ree concentrations of archean and proterozoic chemical sediments are commonly used as proxies to study secular trends in the geochemistry of precambrian seawater in addition similarities in the ree signatures of archean chemical sediments and modern seawater have led researchers to argue that some archean rocks originated as biochemical precipitates i e microbial carbonates in shallow marine e g peritidal environments however terrestrial waters including river water and groundwater also commonly exhibit ree fractionation patterns that resemble modern seawater here we present the seawater like ree data for ground

the development of middle rare earth element enrichments in freshwaters weathering of phosphate minerals abstract many phosphatic minerals of biogenic authigenic and diagenetic origin are distinguished by rare earth element ree compositions which have a well developed middle rare earth element mree enrichment defined by a gradual increase in the shale normalized ratios of ree toward the middle of the ree series la to lu also the ree composition of dissolved matter in the waters of the amazon fly and sepik rivers as well as other river lake and ground waters have well developed mree enrichments the development of mree enrichments was studied through a series of leaching experiments using river bank sediments from the amazon fly sepik and mississippi rivers a well characterized phosphate mineral rich shale with a pronounced mree enrichment in its bulk composition was also leached in order to better assess the relationship between the weathering of phosphate minerals and the formation of mree enriched solutions the two leaching solutions per sediment consisted of filtered lake water at ph 5 and the same water adjusted to ph 2 leaching experiments with the four river sediments result in extensive fractionation whereby the ree compositions of the solutions develop mree enrichments from starting sediments that show no mree enrichments the ph 2 leachates have much higher concentrations of the ree and more fully developed mree enrichments than do the ph 5 leachates the mree enrichments at ph 2 usually form within an hour of starting the experiments the phosphatic shale results show that there is preferential release of large amounts of mree at ph 5 as well as at ph 2 demonstrating the weather ability of the phosphatic minerals at phs of natural freshwaters the sepik river ph 5 experiment also shows significant mree enrichment under near neutral conditions the development and retention of the mree enrichments in the leaching solutions is accompanied by an increase in dissolved phosphate concentrations although the magnitudes of the mree enrichment do not directly correlate with the percent of phosphate released the experimental data suggest that the preferential dissolution of phosphatic minerals during weathering can result in extensive ree fractionation between bulk river sediment and water leading to freshwaters with mree enrichments

the impact of vegetation on ree fractionation in stream waters of a small forested catchment the strengbach case previous studies on waters of a streamlet in the vosges mountains eastern france have shown that strontium and rare earth elements ree mainly originate from preferential dissolution of apatite during weathering however stream water ree patterns normalized to apatite are still depleted in the light ree lree la sm pointing to the presence of an additional lree depleting process vegetation samples are strongly enriched in lree compared to stream water and their sr and nd isotopic compositions are comparable with those of apatite and stream water thus the preferential lree uptake by vegetation might lead to an additional lree depletion of surface runoff in the forested catchment mass balance calculations indicate that the yearly lree uptake by vegetation is comparable with the lree export by the streamlet and therefore might be an important factor controlling lree depletion in river water this is underlined by the observation that rivers from arctic and boreal regions with sparse vegetation appear to be less depleted in lree than rivers from tropical environments or boreal environments with a dense vegetation cover

ice wedge casts in late wisconsinan glaciofluvial deposits southern ontario canada ice wedge casts in late wisconsinan glaciofluvial sand and gravel deposits in southern ontario taper downwards to form a v or funnel shaped morphology ranging from 1 to over 3 m deep and from 1 0 to 2 5 m wide at the top pressure derived primary structures caused by repeated thermal contraction and expansion include upturned strata realigned stones and small folds in the enclosing sediments although paleotemperature is difficult to estimate the presence of ice wedge casts testifies to the former presence of permafrost under prevailing periglacial conditions over this area the regional till stratigraphy constrains the timing of ice wedge growth to ca 15 000 to ca 13 000 bp at this time newly exposed terrains would have occurred in an interlobate area where severe climate created favourable conditions for permafrost to develop due to the close proximity to the receding ice inactive areas in braided rivers such as raised topographic surfaces and sand filled channels with limited vegetation cov

the fennoscandian ice sheet during the late weichselian geothermal evidence geothermal estimates of the ground surface temperatures for the last glacial cycle in northern europe have been analysed during the middle and late weichselian 55 12 kyr bp a substantial part of this area was covered by the fennoscandian ice sheet the analysis of geothermal data allows reconstructing the limits of ice sheet extent and its basal thermal state in the late weichselian ground surface temperatures outside the ice sheet were extremely low from 7 to 17 c within the ice sheet there were both thawed and frozen zones the revealed temperature pattern is generally consistent with the modern one for ground surface temperatures in greenland which makes it possible to consider these ice sheets as analogues the anomalous climatically induced surface heat flux and orbital insolation of the earth varied consistently outside the glaciation and independently within the limits of the ice sheet

use of liquefaction induced features for paleoseismic analysis an overview of how seismic liquefaction features can be distinguished from other features and how their regional distribution and properties of source sediment can be used to infer the location and strength of holocene paleo earthquakes abstract liquefaction features can be used in many field settings to estimate the recurrence interval and magnitude of strong earthquakes through much of the holocene these features include dikes craters vented sand sills and laterally spreading landslides the relatively high seismic shaking level required for their formation makes them particularly valuable as records of strong paleo earthquakes this state of the art summary for using liquefaction induced features for paleoseismic interpretation and analysis takes into account both geological and geotechnical engineering perspectives the driving mechanism for formation of the features is primarily the increased pore water pressure associated with liquefaction of sand rich sediment the role of this mechanism is often supplemented greatly by the direct action of seismic shaking at the ground surface which strains and breaks the clay rich cap that lies immediately above the sediment that liquefied discussed in the text are the processes involved in formation of the features as well as their morphology and characteristics in field settings whether liquefaction occurs is controlled mainly by sediment grain size sediment packing depth to the water table and strength and duration of seismic shaking formation of recognizable features in the field generally requires a low permeability cap above the sediment that liquefied field manifestations are controlled largely by the severity of liquefaction and the thickness and properties of the low permeability cap criteria are presented for determining whether observed sediment deformation in the field originated by seismically induced liquefaction these criteria have been developed mainly by observing historic effects of liquefaction in varied field settings the most important criterion is that a seismic liquefaction origin requires widespread regional development of features around a core area where the effects are most severe in addition the features must have a morphology that is consistent with a very sudden application of a large hydraulic force this article discusses case studies in widely separated and different geological settings coastal south carolina the new madrid seismic zone the wabash valley seismic zone and coastal washington state these studies encompass most of the range of settings and the types of liquefaction induced features likely to be encountered anywhere the case studies describe the observed features and the logic for assigning a seismic liquefaction origin to them also discussed are some types of sediment deformations that can be misinterpreted as having a seismic origin two independent methods for estimating prehistoric magnitude are discussed briefly one method is based on determination of the maximum distance from the epicenter over which liquefaction induced effects have formed the other method is based on use of geotechnical engineering techniques at sites of marginal liquefaction in order to bracket the peak accelerations as a function of epicentral distance these accelerations can then be compared with predictions from seismological models

rare earth element and stable isotope signatures of kaolin from a pliocene lateritic weathering profile at mid latitude region andalusia spain implications for paleoweathering and paleoclimatic reconstructions abstract this study reports the impact of weathering on behavior of rare earth elements ree in a coastal lateritic profile developed on pliocene sediments at mid latitude location 37 n in the guadalquivir basin spain it also explores the stable isotope signature of kaolinite providing constraints on paleotemperature and isotopic composition of the ancient meteoric water the paleoweathering profile 20 m thick comprises a white sandy clayey saprolite overlain by a red mottled clay zone which in turn is capped by a pisolitic ferricrete the kaolinitic regolith was practically reduced to a mixture of kaolinite and quartz by intense chemical weathering under warm and seasonally humid climate the kaolinized material is markedly depleted in total ree mean value of 77 30 mg kg 1 in the white saprolite and 72 70 mg kg 1 in the mottled zone relative to the parent rock 168 96 mg kg 1 development of acidic and oxidizing conditions promoted a suitable soil environment for ree release and leaching with percolating rainwater leading to an apparent loss of ree from the profile up to 87 the parent rock normalized ree patterns display concave upward shapes tracing a remarkable depletion in middle ree mree with no significant anomalies the ree concentrations normalized against the north american shale composite nasc showed consistently similar fractionation patterns the mree depleted signature nasc normalized ratios of la sm up to 3 32 and gd lu as low as 0 45 probably arises from reductive dissolution of iron oxyhydroxide phases due to seasonal water saturation as indicated from redoximorphic features the the lateritic weathering profiles evolved during the mid pliocene warm period in the southwestern iberian margin could be useful for predicting potential future environmental effects of increased atmospheric co2 on the earth s critical zone

the first 7 years 1978 1985 of ice wedge growth illisarvik experimental drained lake site western arctic coast a large lake measuring 600 m 300 m and with a depth of nearly 5 m was artificially drained on 13 august 1978 observations on the formation width and depth of thermal contraction cracks for the first 7 years show that the crack profiles and ice wedge growth rates differ markedly from those of old ice wedges reported in the literature the first winter s cracks had box like profiles with surface widths to 10 cm and depths to 2 5 m some cracks continued to widen and deepen once opened in early winter and then narrowed or even closed completely in summer mean growth rates for the ice wedges for the first few years have been as much as 3 5 cm year temperature gradients at the time of first cracking have been in the range of 10 15 c m the growth rate of young ice wedges is site specific and temperature dependent varying with factors such as the temperature gradient vegetation and snow cover so an estimate of the age of an ice wedge from its width will usually be impossible a study of crack w

supergene sulphate minerals from the burning coal mining dumps in the upper silesian coal basin south poland abstract sulphate minerals of various chemical compositions form subtle mixtures of small aggregated crystals on some burning coal mining dumps in the upper silesian coal basin poland they include na and mg sulphates blodite and konyaite magnesium sulphates belong to the second group and hexahydrite is its most common representative aluminium sulphates include tamarugite pickeringite and alunogen iron sulphates are copiapite group minerals metavoltine butlerite and voltaite group minerals calcium sulphates are almost exclusively represented by gypsum eds proved to be in general a better tool than wds for the chemical analysis of the sulphates both the rietveld and pawley methods were found to be useful in the calculation of unit cell parameters the analysed sulphates contain some rare and interesting elements the most important being tl ga in cd se and as the sulphates formed as a result of the mutual action of various supergene processes including the oxidation of s rich coal fire gases metal leaching from waste rocks by h2so4 solutions and evaporation the complexity of the sulphate efflorescence composition is explained by the chaotic nature of settings involving a variety of waste rocks hydration dehydration reactions and access of both ground and rain water and atmospheric oxygen

mobility and fractionation of rare earth elements during supergene weathering and gossan formation and chemical modification of massive sulfide gossan primary massive sulfide gossans msg in the bathurst mining camp bmc new brunswick canada are characterized by relative enrichment of au sb and as formation of jarosite group minerals jarosite plumbojarosite and argentojarosite and little or no fractionation in the rare earth elements ree including preservation of large positive eu anomalies average eu eu nasc 4 14 in msg 6 61 in massive sulfide mineralization 0 60 in host rocks the chemical and mineralogical characteristics of msg e g halfmile lake deposit imply low ph 3 and relatively oxidizing conditions during gossan formation oxidation of a volcanogenic massive sulfide body comprising pyrite pyrrhotite sphalerite galena and chalcopyrite with a falling water table the lack of light ree or heavy ree fractionation and preservation of positive eu anomalies characteristic of the original 465 ma hydrothermal fluid is consistent with relatively large water rock ratios during massive sulfide mineralization oxidation and removal of the ree predominantly as sulfate complexes lnso4 ln so4 2 low ph groundwaters recovered from past producing mines in the bmc display ree patterns reflecting those inferred to have occurred during gossan formation gossan at the restigouche deposit in contrast to the halfmile lake deposit displays mineralogical and chemical evidence for having been chemically reworked since primary gossan formation evidence for chemical reworking includes loss of primary massive sulfide mineralization textures replacement of plumbojarosite with anglesite almost complete removal of jarosite minerals loss of au sb and as and apparent preferential removal of eu resulting in loss of positive eu anomalies for most samples average eu eu nasc 1 21 in the gossan with many displaying strong negative anomalies 3 65 in massive sulfide mineralization 0 54 in host rocks based on geochemical modeling conditions inferred for the chemical reworking of the restigouche deposit include near neutral conditions and either relatively oxidizing conditions with eu2 hosted in a preferentially weathered mineral host possibly through substitution for pb in plumbojarosite and beudantite or cycling between reduced and oxidized conditions during gossan reworking

attenuation of rare earth elements in a boreal estuary this study focuses on attenuation of rare earth elements ree when a boreal creek acidified and loaded with ree and other metals as a result of wetland drainage empties into a brackish water est

rodents and climate 1 a model for estimating past temperatures using arvicolids mammalia rodentia abstract analysis of 253 extant mammalian local faunas shows that the number of arvicoline species in each fauna is related to temperature parameters the very high correlation allows us to propose a method to estimate the temperature for fossil faunas bearing arvicoline species from temperate areas to illustrate this method mean annual temperatures were estimated for late pleistocene hungarian localities and for a sequence from the baume de gigny jura france these were compared with results obtained by other techniques multivariate analysis of rodent associations and synthetic analysis of pollen faunal and sedimentological data

cycling of trace metals and rare earth elements ree in acid sulfate soils in the plain of reeds vietnam abstract trace metals and rare earth elements ree are subject to intensive chemical cycling in acid sulfate soils the oxidation of pyrite bearing deposits and the subsequent acidification mobilizes a variety of trace metals and ree in this study solid phase and pore water data of three cores from the plain of reeds in the mekong river delta vietnam were analyzed distinct authigenic enrichments of trace metals and ree were observed in the solid phase of these cores thermodynamic modeling was employed to elucidate the controls on trace metal and ree mobility and the governing factors for the formation of these authigenic enrichments the formation of ree enrichments in these settings is clearly controlled by ph and the availability of potent sorbents under suitable conditions trace metals such as e g zinc nickel and cobalt are likely bound as trace metal monosulfides in the enrichment zones the solid phase and pore water data and the results of a thermodynamic model suggest a possible sequential precipitation of trace metal sulfides however the incorporation of trace metals into iron sulfides cannot be ruled out in the case of lead and arsenic the formation of pb as jarosite proved to be a further major sink these insights provide a better understanding of the controls and governing factors for trace metal and ree mobility in acid sulfate soils and will therefore help to assess impacts on soil and water

looking for jarosite on mars the low temperature crystal structure of jarosite single crystal diffraction of jarosite kfe 3 3 so 4 2 oh 6 has been undertaken at low temperatures that proxy for martian surface conditions room temperature data are consistent with literature data a 7 2913 5 c 17 1744 17 and v 790 72 11 in r 3 m while the first low temperature data for the mineral is presented at 253 213 173 and 133 k data collections between 297 and 133 k show strongly anisotropic thermal expansion with the c axis much more expandable than the a axis much of the anisotropy is due to strong distortion of the ko 12 polyhedron which increases by 8 between 297 and 133 k the data sets can aid in the identification of jarosite by x ray diffraction of martian soils using the curiosity rover s chemin instrument