isotopic composition of old ground water from lake agassiz implications for late pleistocene climate a uniform oxygen isotope value of 25 per mil was obtained from old ground water at depths of 20 to 30 meters in a thick deposit of clay in the southern part of the glacial lake agassiz basin the lake occupied parts of north dakota and southern manitoba at the end of the last glacial maximum and received water from the ice margin and the interior plains region of canada ground water from thick late pleistocene age clay deposits elsewhere a till in southern saskatchewan and a glaciolacustrine deposit in northern ontario show the same value at similar depths these sites are at about 50 n latitude span a distance of 2000 kilometers and like the lake agassiz sites have a ground water velocity of less than a few millimeters per year the value of 25 per mil is characteristic of meltwater impounded in the southern basin of lake agassiz this value corresponds to an estimated air temperature of 16 c compared with the modern temperature of 0 c for this area

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d0 in free water the stable isotope profile however indicates a component of fossil marine pore water which has not yet been replaced by molecular diffusion of meteoric water from the adjacent limestone and shale formations over the past 10 million years

mineralogical and isotopic record of biotic and abiotic diagenesis of the callovian oxfordian clayey formation of bure france abstract the callovian oxfordian cox clayey unit is being studied in the eastern part of the paris basin at depths between 400 and 500 m depth to assess of its suitability for nuclear waste disposal the present study combines new mineralogical and isotopic data to describe the sedimentary history of the cox unit petrologic study provided evidence of the following diagenetic mineral sequence 1 framboidal pyrite and micritic calcite 2 iron rich euhedral carbonates ankerite sideroplesite and glauconite 3 limpid calcite and dolomite and celestite infilling residual porosity in bioclasts and cracks 4 chalcedony 5 quartz calcite pyrite in bioturbations shows a wide range of 34s 38 to 34 5 providing evidence of bacterial sulphate reduction processes in changing sedimentation conditions the most negative values 38 to 22 measured in the lower part of the cox unit indicate precipitation of pyrite in a marine environment with a continuous sulphate supply the most positive pyrite 34s values 14 up to 34 5 in the upper part of the cox unit indicate pyrite precipitation in a closed system celestite 34s values reflect the last evolutionary stage of the system when bacterial activity ended however its deposition cannot be possible without sulphate supply due to carbonate bioclast dissolution the 87sr 86sr ratio of celestite 0 706872 0 707040 is consistent with deposition from jurassic marine derived waters carbon and oxygen isotopic compositions of bulk calcite and dolomite are consistent with marine carbonates siderite only present in the maximum clay zone has chemical composition and 18o consistent with a marine environment its 13c is however lower than those of marine carbonates suggesting a contribution of 13c depleted carbon from degradation of organic matter 18o values of diagenetic chalcedony range between 27 and 31 suggesting precipitation from marine derived pore waters late calcite crosscutting a vein filled with chalcedony and celestite and late euhedral quartz in a limestone from the top of the formation have lower 18o values 19 suggesting that they precipitated from meteoric fluids isotopically close to present day pore waters of the formation finally the study illustrates the transition from very active biotic diagenesis to abiotic diagenesis this transition appears to be driven by compaction of the sediment which inhibited movement of bacterial cells by reduction of porosity and pore sizes rather than a lack of inorganic carbon or sulphates

veins in clay rich aquitards as records of deformation and fluid flow events in northern switzerland abstract the jurassic clay rich aquitard sequence underlying the swiss molasse basin is locally penetrated by unusually frequent veins consisting of calcite celestite in particular in the schlattingen 1 and oftringen drill cores the veins are linked to extensional brittle structures with shear senses ranging between dip slip and strike slip deformation triggered transient and localised events of fluid flow within the aquitard followed by sealing of the structures by the vein minerals vein calcite was dated by la icp ms analysis using the u pb method while this was a demanding undertaking given the low u and high common pb contents of calcite 9 significant ages could be obtained two groups of ages can be distinguished namely 31 39 and 11 18 ma both age groups are consistent with the known regional tectonic evolution the older age group corresponds to the main phase of rifting in the upper rhine graben a major crustal discontinuity whose effects were not limited to the graben proper but affected large parts of the molasse basin the younger age group is linked to crustal tilting and related extensional deformation isotopic compositions of o and c in vein calcite from the schlattingen 1 core show substantial variability but do not discriminate between veins of the two age groups in contrast 87sr 86sr ratios in veins show different signatures the depth trend of 87sr 86sr ratios in veins fits well with that in pore water obtained by rock squeezing the two data sets define a trend of values increasing with depth connecting the current values in the embedding malm and keuper aquifer waters this trend is best explained as a near steady state diffusion profile while advective mixing of waters originating from the embedding aquifers to produce the veins implying structures that cross cut the whole low permeability sequence cannot be discarded on the basis of existing data it is considered more likely that the veins have local fluid sources these are mixtures of local pore water with a possible contribution of water from the nearest aquifer implying maximum vertical advection distances in the order of 50 100 m

architecture and growth of normal fault zones in multilayer systems a 3d field analysis in the south eastern basin france abstract 3d field data on mesoscale normal faults were collected to examine the geometries and growth of faults in multilayer systems observation and analysis of the fractures include the collection of geometric attributes such as fault dips and fault zone thicknesses detailed mapping in cross sections and plan views and the construction of individual and cumulative displacement profiles fault zone growth is consistent with a coherent model and is strongly influenced by the multilayer system in the limestone layers faults grew in several steps including opening and frictional sliding on 80 dipping segments faulting in clay layers was in the form of 40 dipping faults and sub horizontal faults the latter being mostly early features developed under the same extensional regime as normal faults and disturbing the fault architecture the fault zone thickness increases with the limestone thickness and the presence of sub horizontal faults in clay beds numerous connections occur in clay units the moderate 0 08 and low

use of vertical profiles of δ18o to constrain estimates of hydraulic conductivity in a thick unfractured aquitard vertical distributions of 18o were used to constrain hydraulic conductivity k in a thick unfractured aquitard previous investigations utilizing permeability tests at a variety of scales keller et al 1989 indicated that bulk k at the site ranges from 3 5 0 11 m s to 1 2 10 10 m s advective displacements calculated on the basis of these k values lead to a wide range of predicted distributions of natural tracers after 11 000 years comparison of 18o distributions and simulated advection diffusion profiles provide a more precise constraint on advective displacement and hence on k the simulations cast in terms of a peclet number p v2t d ranging in value from 0 to 12 indicate that transport is diffusion controlled and that k is actually less than 1 2 10 11 m s p greater than 0 1 k 1 2 10 11 m s overestimates transport this result indicates that conventional permeability tests in very tight media tend to overestimate k in practical terms advective transport at the site is negligible and transport can be simulated with diffusion only p o

the jura mountains an active foreland fold and thrust belt abstract recently completed in situ stress measurements using the borehole slotter at 33 new test sites within the swiss and french jura mountains combined with previously published stress data allow a detailed description of the contemporary state of stress in this fold and thrust belt and the adjacent foreland five stress provinces can be recognized with two different general orientations of maximum horizontal stress sh 1 the central and southwest provinces with a nnw sse to nne ssw orientation 2 the east northwest and southeast provinces with an e w to nw se orientation stress magnitudes are in general higher in the southern than in the northern jura mountains characteristic of the northern jura is an e w trending zone of low stress magnitudes which can be traced from the bresse depression south of besancon to the eastern end of the jura northwest of zurich boundaries of stress provinces show poor agreement with boundaries of tectonic units in the jura in addition stress provinces extend beyond the boundaries of the jura mountains into their foreland furthermore palaeo stress orientations show large discrepancies with respect to the contemporary stress orientation these findings are considered to indicate a termination of jura thin skinned foreland tectonics which probably took place some time between 9 and 4 ma according to palaeontological and tectonic evidence it is suggested that a new style of tectonics has commenced in the jura mountains deforming both the basement directly below the jura fold and thrust belt and the cover rocks in a similar mode

influence of gold mine on groundwater quality efemcukuru izmir turkey currently exploration of gold ores is under discussion in turkey without considering its adverse affect on the environment studying the adverse affect on environment is extremely important because significant civic activities are already taking place on the geological units that contain gold ore bodies in turkey such an area is located at the southeast of izmir city turkey and approximately 2 km long gold bearing ore veins occur close to the efemcukuru village the objective of this study was to describe the characteristics and seasonal variation of the groundwater chemistry and pollution of the aquifer in the ore deposit site and to determine the impact of ore deposits on groundwater quality the gold bearing formation is highly weathered and fractured the fractures in the geological units control the permeability and the depth of groundwater in the area the concentrations of al ag cu cd cr fe pb mn zn ni and sb were determined for four well samples and two stream waters for wet and dry seasons the results showed that the concentrations of most of these elements were below the usa epa environmental protection agency limits however pb and cd concentrations are slightly above the limits the results indicate that minerals in gold bodies do not dissolve although the weathering of formations is high the low concentration of elements in groundwater and streams may be attributed to the high velocity of ground and surface water

world wide delivery of river sediment to the oceans new data and new estimates from old data show that rivers with large sediment loads annual discharges greater than about 15 times 10 6 tons contribute about 7 times 10 9 tons of suspended sediment to the ocean yearly extrapolating available data for all drainage basins the total suspended sediment delivered by all rivers to the oceans is about 13 5 times 10 9 tons annually bedload and flood discharges may account for an additional 1 2 times 10 9 tons about 70 of this total is derived from southern asia and the larger islands in the pacific and indian oceans where sediment yields are much greater than for other drainage basins

tectonics of the central swiss molasse basin post miocene transition to incipient thick skinned tectonics in this paper we investigate the tectonics of the central swiss molasse basin smb situated between the central european alps and the jura fold and thrust belt based on re interpreted 2d reflection seismic data and geological 3d modeling we present new insights into the structural configuration and evolution of the central smb during the thin skinned main deformation phase of the jura fold and thrust belt 12 4 ma the central smb was riding passively above a major detachment horizon within triassic evaporites which roots beneath the external crystalline massifs of the central alps in the smb low amplitude detachment folds and detachment rooted wsw ene striking thrust and reverse faults are related to this event younger major nne ssw and nnw sse trending strike slip fault zones cross the basin over a length of several kilometers affecting the cenozoic and mesozoic cover units and extending into the pre mesozoic crystalline basement in cases the fault zones apparently reactivate inherited permo carboniferous trough pct bounding paleozoic normal faults seismic data further reveals mild inversion of wsw ene striking pcts these structures clearly cut the basement cover contact thus postdating the main deformation phase of the jura fold and thrust belt present day earthquake focal mechanisms and epicenter distribution show strike slip faulting and basement seated seismicity respectively thus corroborating our observations from seismic interpretation our data suggests a change from late miocene thin skinned to pliocene to present day incipient thick skinned tectonics this major change reflects the establishment of a mid crustal detachment and may be related to changes in slab dynamics of the subducting european lithosphere

layering and structural inheritance controls on fault zone structure in three dimensions a case study from the northern molasse basin switzerland mechanical heterogeneity of a sedimentary sequence exerts a primary control on the geometry of fault zones and the proportion of offset accommodated by folding the wildensbuch fault zone in the swiss molasse basin with a maximum throw of 40 m intersects a mesozoic section containing a thick 120 m clay dominated unit opalinus clay over and underlain by more competent limestone units interpretation of a 3d seismic reflection survey indicates that the fault zone formed by upward propagation of an east west trending basement structure through the mesozoic section in response to ne sw miocene extension this configuration formed an array of left stepping normal fault segments above and below the opalinus clay in cross section a broad monoclinal fold is observed in the opalinus clay folding however is not ubiquitous and occurs in the opalinus clay where fault segments above and below are oblique to one another where they are parallel the fault passes through the opalinus clay with little folding these observations demonstrate that even in strongly heterogeneous sequences here a four fold difference in both young9s modulus and cohesion between layers the occurrence of folding may depend on the local relationship between fault geometry and applied stress field rather than rheological properties alone

stable water isotopes in pore water of jurassic argillaceous rocks as tracers for solute transport over large spatial and temporal scales 1 in order to characterize the large scale transport properties of the opalinus clay formation the pore water isotope composition 18o and 2h was determined on samples from the deep borehole benken northeastern switzerland across jurassic argillaceous rocks the sequence of claystones and marls delimited by two aquifers is located at depth from about 400 to 700 m and exhibits very low hydraulic conductivities below 10 13 m s 1 the isotope data of the pore water were obtained from core samples by diffusive vapor equilibration vacuum distillation and squeezing compared with the other methods vacuum distillation led to too low values to evaluate the large scale transport properties of the formation we performed a series of advective dispersive model calculations and compared them with the experimental data in accordance with the hydrogeological history we varied initial and boundary conditions as well as model parameters the main results can be summarized as follows 1 molecular diffusion to the underlying aquifer can explain the general features of the isotope profiles 2 no signatures of advective flow could be detected 3 the evolution time is of the order of 0 5 1 ma relying on laboratory diffusion coefficients with a possible range of about 0 2 2 ma which is geologically plausible and 4 parameters measured on small scales centimeters or meters and months are also plausible at the formation scale tens of meters and millions of years for the sediments investigated

hydrochronology of a proposed deep geological repository for low and intermediate level nuclear waste in southern ontario from u pb dating of secondary minerals response to silurian and cretaceous events u pb ages have been measured on secondary dolomite and silica cements in cambrian sandstone at the base of an 840 m thick sub horizontally bedded sedimentary sequence beneath the bruce nuclear site

effects of silt clay content on the susceptibility of river banks to subaerial erosion abstract the aim of this paper is to demonstrate how subaerial processes vary with the silt clay content of river bank soil and to consider this variation in the context of erosion observed in the field in particular spatial and temporal variations in erosion interactions with other bank erosion processes and the implications for bank morphology are explored a number of soil blocks of known silt clay content were subjected to a series of freeze thaw and drying wetting cycles changes in the dimensions of the soil blocks were recorded and the mass of soil eroded from each block together with maximum size of eroding aggregates were measured limitations to this methodology are acknowledged including a limited ability to replicate the forces to which a river bank may be subject restrictions imposed by the available equipment in producing temperature and humidity cycles which reflect those occurring in the field and issues of scale the results indicate that river banks with high silt clay contents are the most susceptible to erosion by subaerial processes high susceptibility may influence spatial variations in bank erosion processes and rates including downstream changes in the effectiveness and significance of subaerial erosion a vertical zoning of processes on a river bank is recognised whereby the upper part of the bank is subject to subaerial erosion and the lower part to fluvial erosion given that a high silt clay content tends to indicate increased susceptibility to subaerial erosion but increased resistance to fluvial erosion this vertical zoning may have implications for bank morphology

characterization of complex fluvial systems using remote sensing of spatial and temporal water level variations in the amazon congo and brahmaputra rivers the surface water and ocean topography swot satellite mission will provide global space based estimates of water elevation its temporal change and its spatial slope in fluvial environments as well as across lakes reservoirs wetlands and floodplains this paper illustrates the utility of existing remote sensing measurements of water temporal changes and spatial slope to characterize two complex fluvial environments first repeat pass interferometric sar measurements from the japanese earth resources satellite are used to compare and contrast floodplain processes in the amazon and congo river basins measurements of temporal water level changes over the two areas reveal clearly different hydraulic processes at work the amazon is highly interconnected by floodplain channels resulting in complex flow patterns in contrast the congo does not show similar floodplain channels and the flow patterns are not well defined and have diffuse boundaries during inundation the amazon floodplain often shows sharp hydraulic changes across floodplain channels the congo however does not show similar sharp changes during either infilling or evacuation second shuttle radar topography mission measurements of water elevation are used to derive water slope over the braided brahmaputra river system in combination with in situ bathymetry measurements water elevation and slope allow one to calculate discharge estimates within 2 3 accuracy these two studies illustrate the utility of satellite based measurements of water elevation for characterizing complex fluvial environments and highlight the potential of swot measurements for fluvial hydrology copyright 2010 john wiley sons ltd

partitioning of metals in sediments of the haraz river southern caspian sea basin the haraz river flows northwards through the iranian alborz mountains in the central region of mazandaran province and empties into the caspian sea this area has been a rich source of minerals from times immemorial about 45 mines coal limestone sand and gravel etc have been operational for the last eight decades towards the estuary the river receives a discharge of industrial agricultural and urban wastes eight sediment samples from the haraz river and its main tributaries were collected and analyzed for base metals as well as sr and fe the chemical partitioning of metals cu zn as cd pb fe ni cr co and sr in each sample was determined in four fractions acid soluble reducible oxidizable and residual the total content of each metal was also determined the results showed relatively higher concentrations of cd as sr and pb in comparison to that of shale however based on the chemical partitioning of metals it is found that pb co cd and sr are the most mobile metals in spite of the high as concentrations in sediments it is not likely that this element is a major hazard for the aquatic environment since it is found mainly in the residual fraction cadmium is the metal that showed the highest percentages in the acid soluble fraction the most labile and the lowest in the residual fraction however fe cr and ni are present in the greatest percentages in the residual fraction which implies that these metals are strongly linked to the sediments

identifying temporally and spatially changing boundary conditions at an aquifer aquitard interface using helium in porewater abstract helium concentrations and 3he 4he isotope ratios of porewater groundwater and rock were measured on samples collected from a jurassic sediment sequence at the mont terri underground rock laboratory northern switzerland porewater he data of rock samples collected from borehole bdb 1 at high spatial resolution across a karstic limestone unit passwang formation into the underlying claystone sequence opalinus clay staffelegg formation describe a continuous profile from the water conducting zone in the limestone into the clay rich rocks of low permeability concentrations of 4he 3he and their parent nuclides in the rock allow calculating in situ production and accumulation terms since the time of sedimentation 90 97 of the in situ produced 4he has been released to the porewater today only 2 5 of the maximum possible accumulated 4he is still retained in the porewater while the major part of in situ produced 4he was removed from the system presumably by porewater groundwater exchange the porewater 4he concentrations show a diffusion profile from the aquitard towards the aquifer reflecting a a transient state between 4he in situ production and porewater groundwater exchange b a transient state from previously higher 4he concentrations in the porewater and c a spatially variable boundary in the karstic limestone unit evolutionary models of porewater 4he concentration profiles in combination with constraints from independent chemical and isotopic tracers allow deciphering a complex palaeo hydrogeological history of the system over about the last 30 ka a local excursion from the general profile towards higher 4he concentrations and 3he 4he ratio in a limestone layer in the opalinus clay cannot be further constrained in time based on the present sample frequency but appears to represent a hydrogeological signal

drainage morphometry and its influence on hydrology in an semi arid region using srtm data and gis an attempt has been made to study drainage morphometry and its influence on hydrology of peddavanka watershed south india drainage networks for the sub basins were derived from topographical map 1 50 000 and shuttle radar topographic mission srtm digital elevation model dem data used for preparing elevation slope and aspects maps geographical information system gis was used in evaluation of linear areal and relief aspects of morphometric parameters the study reveals that srtm dem and gis based approach in evaluation of drainage morphometric parameters and their influence on hydrological characteristics at watershed level is more appropriate than the conventional methods the mean bifurcation ratio r b of the entire basin is 3 88 which indicate that the drainage pattern is not much influenced by geological structures viii sub basin have high elongation ratio r e basin relief b h ruggedness number rn and time of concentration t c it indicates that the erosion and peak discharges are high in these basins therefore the construction of the check dams and earth dams will help in reducing peak discharge on the main channel these studies are very useful for implementing rainwater harvesting and watershed management

quantitative geomorphology applied to fluvial dynamic in aviles and moneta basins tierra del fuego southern argentina the morphometric characteristics of the moneta river basin are compared to those of the aviles river basin both are located in the north of the province of tierra del fuego in argentina and they also have their catchment area in the same range the sierras del bosque runoff on the ne oriented slopes forms the aviles river basin while runoff on the se slopes forms the moneta river basin the analysis was made in two different scales the first as a general scale of the basin and the second as the catchment sector upper middle and lower the quantitative analysis was applied in order to know the behavior of these two fluvial systems for the analysis a cartographic basis scale to 1 20 000 was used which was made on a mosaic of images from google earth the altimetric information was obtained throughout a digital elevation model of 45 m spatial resolution srtm45 shuttle radar topographic mission the indices used were rr rb ish and dd to characterize the geological and geomorphological context and rl re if ct and ca to infer the behavior of the runoff in the catchment it was established that the moneta river basin reaches 6 in order of hierarchy its main channel is 65 52 km long the re determines an elongated basin the ct obtained in the basin is 0 96 whereas the sub basin level was identified to a maximum value of the o3 sm 10 1 46 the dd is low 1 94 km km2 which is directly proportional to the intensity of rainfall and the slopes of the area considered the comparison made at the same scale between basins determines specific fluvial characteristics of each sector upper middle and lower

phosphor imaging as a tool for in situ mapping of ppm levels of uranium and thorium in rocks and minerals abstract phosphor imaging is a type of digital autoradiography that has been widely used in biochemistry to examine radioactively tagged proteins we used phosphor imaging to map in situ u and th in polished slabs of geological materials including carbonates phosphates and silicate rich rocks we examined samples containing between 2 and 500 ppm u and 700 ppm th to evaluate the applicability of the technique to geological samples resolution of 1 mm or better was obtained even for low concentration 10 ppm samples these analyses are routine and only require a light box phosphor screen and access to a phosphor imager the technique is nondestructive relatively inexpensive and requires very little processing time we used this technique to identify u and th enriched carbonates and phosphates and to find hot spots of u and th rich minerals in a granodiorite these high resolution maps of u and th allow us to effectively sample for geochronology and identify potentially interesting samples for synchrotron x radiation studies the maps produced by phosphor imaging also have great potential for investigating the details of adsorption of radionuclides to rocks and minerals in contaminated areas

characterizing the hydrogeology of a complex clay rich aquitard system using detailed vertical profiles of the stable isotopes of water abstract high resolution 1d profiles of the stable isotopes of porewater 2h and 18o obtained by direct porewater equilibration of core samples were used to identify hydrogeologic zones in a thick complex till aquitard system in saskatchewan canada detailed 1d isotope profiles revealed the presence of three distinct hydrogeological zones an upper 5 10 m an intermediate 10 30 m and a lower 30 62 5 m till zone the upper hydrogeological zone was controlled by a sand layer having a high hydraulic conductivity k the lack of vertical variability in the stable isotope data in the intermediate zone suggested groundwater flow and solute transport was controlled by a system of interconnected vertical fractures and lateral sand layers the curved shape of the isotope profile in the lower till zone suggested that solute transport in this zone was controlled mainly by molecular diffusion we show that high resolution vertical stable isotope profiles of porewater obtained from core samples and direct equilibration yield cost effective and invaluable hydrogeologic information on groundwater flow in aquitard systems that cannot be realistically obtained by construction of costly conventional piezometer bundles i e 2h and 18o analyses of water samples and k determinations further the direct equilibration approach overcomes the problem of piezometer leakage in low k aquitards

graben width controlling syn rift sedimentation the palaeogene southern upper rhine graben as an example eocene to early oligocene syn rift deposits of the southern upper rhine graben urg accumulated in restricted environments sedimentation was controlled by local clastic supply from the graben flanks as well as by strong intra basinal variations in accommodation space due to differential tectonic subsidence that in turn led to pronounced lateral variations in depositional environment three large scale cycles of intensified evaporite sedimentation were interrupted by temporary changes towards brackish or freshwater conditions they form three major base level cycles that can be traced throughout the basin each of them representing a stratigraphic sub unit a relatively constant amount of horizontal extension l in the range of 4 5 km has been estimated for the urg from numerous cross sections the width of the rift lf however varies between 35 and more than 60 km resulting in a variable crustal stretching factor between the bounding masterfaults apart from block tilting tectonic subsidence was therefore largely controlled by changes in the initial rift width l0 the along strike variations of the graben width are responsible for the development of a deep trough like evaporite basin potash basin in the narrowest part of the southern urg adjacent to shallow areas in the wider parts of the rift such as the colmar swell in the north and the rhine bresse transfer zone that delimits the urg to the south under a constant amount of extension the along strike variation in rift width is the principal factor controlling depo centre development in extensional basins

strontium distribution and origins in a natural clayey formation callovian oxfordian paris basin france a new sequential extraction procedure strontium is a good monitor of geochemical processes in natural clayey formations in the callovian oxfordian formation of bure in france strontium is sorbed on clay minerals and carried by carbonates detrital minerals and accessory celestite in order to determine the strontium distribution among these different phases four step sequential extractions 1 cobalt hexamine trichloride 2 acetic acid 3 edta and 4 tri acid were performed on samples from different levels of the clayey formation the leachates were also analyzed for strontium isotopes in order to determine the strontium origins this sequential procedure is well suited to determining strontium distribution in claystones although it is less efficient in clay rich limestones and in celestite rich samples the carbonates 38 47 of the total strontium show 87sr 86sr ratios 0 7070 0 7071 that have recorded the isotopic composition of the callovian oxfordian seawater diagenetic carbonates dolomite ankerite and siderite have almost not incorporated any strontium which has been trapped by celestite during the late diagenesis the major part of the celestite shows 87sr 86sr ratios 0 7069 0 7070 quite close to the primary carbonates however a second generation of celestite 0 7074 shows a slight 87sr enrichment and is isotopically in equilibrium with the exchangeable strontium 27 48 of the total strontium with a mean 87sr 86sr value of 0 70745 and the present day porewater 0 7074 this very low 87sr enrichment could be explained by the partial destabilisation of detrital minerals feldspars micas clays which exhibit 87sr 86sr ratios consistent with their pristine hercynian origin 0 7229 0 7350 diffusion of strontium from the subjacent dogger aquifers 0 7076 0 7082 could also be invoked to explain the slight 87sr enrichment

upper rhine graben role of preexisting structures during rift evolution 1 the evolution of the cenozoic upper rhine graben was controlled by a repeatedly changing stress field and the reactivation of a complex set of crustal discontinuities that had come into evidence during permo carboniferous times a comparison of the spatial and temporal thickness distribution of synrift deposits with preexisting fault patterns permits to infer a sequence of distinct basin subsidence phases that can be related to changes in the ambient stress field reactivation of a system of late palaeozoic fault systems outlining troughs and highs controlled the nucleation of initially separated middle and late eocene basins the depocenters of which coincided with a preexisting wsw ene trend during oligocene crustal extension the individual basins coalesced resulting in the development of the ssw nne striking upper rhine graben during the late oligocene chattian change in stress field the upper rhine graben was probably reactivated as a dextral strike slip system with the central graben segment forming a releasing bend during the early miocene aquitanian a major reorientation of the regional stress field is held responsible for the main subsidence phase of the northern parts of the upper rhine graben this is reflected by a counterclockwise rotation and northeastward shift of the depocenter axis and later by the middle miocene uplift and erosion of the southern parts of the upper rhine graben during the plio quaternary the upper rhine graben was reactivated as a sinistral strike slip system with the central graben segment forming a restraining bend

coupled study of water stable isotopes and anions in porewater for characterizing aqueous transport through the mesozoic sedimentary series in the eastern paris basin abstract this study presents data on chloride and bromide concentrations in porewater water and anion diffusion coefficients and their accessible porosities based on radial diffusion experiments on rock samples collected from a 2000 m deep borehole est433 drilled by andra in the eastern paris basin the distributions of water stable isotope and chloride concentrations in porewater along this column reveal transient flows of water and solutes between the aquitard layers and the surrounding aquifers these distributions confirm the occurrence of two separate aquitard aquifer systems oxfordian callovo oxfordian dogger and dogger liassic rhaetian this separation is confirmed by cl br ratios which are low in liassic and dogger porewater suggesting the influence of primary brines and which are close to the marine ratio in the dogger groundwater based on these results transport simulations in the two systems were carried out according to different scenarios the simulation results confirm that transport properties obtained in the laboratory at sample scale may be extrapolated to the formation scale it is highly probable that diffusion is the main transport process in the callovo oxfordian formation this may also be the case in the dogger liassic layer although a limited contribution from advection cannot be totally excluded by testing different scenarios of boundary conditions in diffusive models it is proposed that the dogger aquifer was first activated in the early miocene

terras caidas fluvial erosion or distinct phenomenon in the amazon in the amazon river basin as in other hydrographic regions of brazil and the world fluvial erosion processes occur because of rivers dynamics however the lateral erosion that occurs on banks of amazonian rivers called terras caidas typically is associated with gravitational movements and is mainly related to large landslides that can damage structures or kill people who live along these riverbanks to better understand the erosive processes that occur in rivers of northern brazil especially those located in the amazon river basin this work aims to describe the terras caidas phenomenon and determine whether it is a distinct phenomenon of fluvial erosion processes the investigation includes analysis of hydrometeorological data of the national water agency ana information collected during field expeditions and mapping of geological and hydrological risk areas in the states of amazonas acre rondonia para and amapa performed by the geological survey of brazil cprm from 2011 to 2016 it is concluded that terras caidas is a distinct phenomenon in the amazon rivers that is different from erosive processes in other brazilian rivers because it is associated not only with the lateral erosion but also with mass movements of moderate and large extents which cause landslips undermining creeps and major landslides

european cenozoic rift system abstract the european cenozoic rift system extends from the coast of the north sea to the mediterranean over a distance of some 1100 km it finds its southern prolongation in the valencia trough and a plio pleistocene volcanic chain crossing the atlas ranges development of this mega rift was paralleled by orogenic activity in the alps and pyrenees major rift domes accompanied by subsidence reversal of their axial grabens developed 20 40 ma after beginning of rifting uplift of the rhenish shield is related to progressive thermal lithospheric thinning the vosges black forest and the massif central domes are probably underlain by asthenoliths emplaced at the crust mantle boundary evolution of this rift system is thought to be governed by the interaction of the eurasian and african plates and by early phases of a plate boundary reorganization that may lead to the break up of the present continent assembly

fibrous calcite veins overpressures and primary oil migration the fibrous calcite veins found parallel to the bedding of certain shales may have been formed during burial as a consequence of overpressuring their presence could even be indicative of former overpressures this suggestion if it can be upheld carries implications for theories of primary oil migration

diffusion as the main process for mass transport in very low water content argillites 2 fluid flow and mass transport modeling 1 on the basis of chloride concentrations of pore water in the tournemire massif part 1 a conceptual model for mass transport in argillites by diffusion is proposed from this conceptual model and current knowledge of the geological history of the massif one dimensional numerical simulations are formulated for chloride transport in tournemire massif over the past 53 ma good agreement between experimental data and calculated values for both diffusion coefficients and concentrations of chloride confirms that diffusion is the main process for mass transport in the massif this model is also tested using deuterium contents of pore water applying variable concentrations to meteoric water circulating in system boundary layers based on the thermal dependency of its isotopic composition these simulations reveal the likely important role of lithologic heterogeneities such as fractures in the horizontal distribution of tracer concentrations

the holocene alluvial plain of the middle amazon river brazil abstract the fluvial belt of the amazon river is a complex of quaternary sedimentary units of different ages and formation conditions present position of the channel and the morphology and size of the alluvial plain are related to neo tectonic lineaments in the study area the main channel of the solimoes is nearly straight the river may be considered anastomosed albeit with few islands and anabranches the main holocene units are the impeded floodplain and the channel dominated floodplain the channel dominated floodplain is a complex mosaic of fluvial forms including younger channels active sandbars islands levees scroll dominated plains and abandoned belts the impeded floodplain is a widespread unit characterised by a very flat surface and round or irregularly shaped lakes the impeded drainage flood plain is only partially affected by the present floods and even those parts affected by floods receive little or no sediment from the main channel more important sediment contribution is by alluvial plain channels from the solimoes branches that generate deltas in the impeded floodplain lakes the impeded floodplain is interpreted to be an earlier stage in the evolution of the holocene alluvial belt the formation was marked by widespread vertical accretion and a channel morphogenetically less active than at present the later stage is associated with an active main channel and the paranas and generation of a scroll dominated plain this very large river system had a complex and delayed response to variations in the hydrological conditions induced by changes in the regional climate during the late holocene

origin age and movement of pore water in argillaceous quaternary deposits at four sites in southwestern ontario hydrogeologic information in the form of textural properties field and laboratory determined hydraulic conductivity values vertical hydraulic gradients from piezometer nests and major ion and isotopic contents 18o 2h 3h 13c 14c was obtained from four sites located in southwestern ontario on thick deposits of clayey till and glaciolacustrine clay at each site the piezometers were installed from the water table zone situated 1 4 m below the surface to a maximum depth between 20 and 35 m below the surface values of hydraulic conductivity determined in the laboratory by consolidometer and triaxial methods are in the order of 10 8 10 7 cm s and are similar to values calculated from rates of water level rise in piezometers mean values of average vertical groundwater velocity calculated with the measured values of hydraulic conductivity porosity and hydraulic gradient using the darcy equation for a saturated non fractured porous medium range from 0 13 to 0 26 cm yr tritiated pore waters only occur within 3 6 m of ground surface thereby indicating that groundwaters below this depth recharged prior to at least 1952 18o in the pore waters exhibit a distinctive regular shift with depth from water table values of 9 to 10 smow characteristic of present day precipitation to values between 14 and 17 at depths of 20 40 m which are characteristic of much cooler waters corrected 14c ages of the groundwater are greater than 8000 yr b p thereby suggesting that the groundwaters at depth entered these deposits during or after the formation of these deposits approximately 11 000 to 14 000 yr ago 18o 2h and cl concentration profiles were simulated with a one dimensional model for transport by advection and diffusion in a saturated porous medium reasonable agreement between the model and the field profiles was obtained with values of effective diffusion coefficients of 3 0 10 6 cm2 s for 18o 2h and cl and with groundwater velocities between 0 03 to 0 05 cm yr based on these results it is concluded that the pore water in these deposits is a mixture of late pleistocene and modern waters and that the distribution of 18c 2h and cl in these deposits is influenced predominantly by molecular diffusion apparently more so than by hydraulic flow

large scale tracer profiles in a deep claystone formation opalinus clay at mont russelin switzerland implications for solute transport processes and transport properties of the rock abstract natural tracers cl and stable water isotopes in pore water of the opalinus clay and adjacent formations were studied in the motorway tunnel at mont russelin switzerland the opalinus clay occurs in the core of an anticline which is cut by a complex system of thrust faults concentration profiles of natural tracers were taken from 17 boreholes along a 363 m long section pore waters of drillcore samples were analysed with indirect and direct methods the cl and stable water isotope distribution in the pore water shows a regular and well defined profile with a conspicuous decrease towards the overlying dogger limestone aquifer the highest cl values approximately 23 000 mg l are found in the core of the anticline in liassic claystones underlying the opalinus clay to quantify the large scale transport properties of the opalinus clay formation a 2d transport model was constructed and used to reproduce the observed concentration profiles the calculations indicate that the observed tracer distributions are consistent with diffusion as the dominant transport process groundwater flow in the overlying dogger aquifer was initiated about 2 4 ma ago which is long after the folding of the jura mountains and probably coincides with the exposure of the aquifer to freshwater recharge following continued erosion of the anticline the calculations suggest that tracer distributions are controlled by 1 the timing of freshwater recharge in the overlying limestone aquifer 2 the shape of the anticline and 3 the magnitude and the anisotropy ratio of diffusion coefficients

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

constraining porewater chemistry in a 250m thick argillaceous rock sequence the geochemistry of an argillaceous rock sequence from a deep borehole in ne switzerland was investigated the focus was to constrain the porewater chemistry in low permeability jurassic rocks comprising the liassic the opalinus clay formation the brown dogger unit and the effingen member malm a multi method approach including mineralogical analysis aqueous and ni ethylenediamine extraction squeezing tests and pco2 measurements as well as geochemical modelling was applied for this purpose a consistent dataset was obtained with regard to the main solutes in the porewaters a fairly constant anionaccessible porosity of 50 of the total porosity was deduced for all analysed samples which displayed variable clay mineral contents sulphate concentrations were shown to be constrained by a sulphate bearing phase presumably by celestite or a sr ba sulphate application of a simple equilibrium model including cation exchange reactions calcite and celestite equilibrium showed good agreement with squeezing data indicating the suitability of the modelling approach to simulate porewater chemistry in the studied argillaceous rocks the modelling highlighted the importance of correct determination of the exchangeable cation population the analysis corroborates that squeezing of the studied rocks is a viable and efficient way to sample porewater

the role of precursory structures on tertiary deformation in the black forest hegau region structural inheritance of preexisting crustal discontinuities is widely accepted to have played a crucial role during the cenozoic tectonic evolution of the northern alpine foreland it is recognised as a process that can strongly influence local fault kinematics and strain patterns the case study presented herein is dedicated to the tectonic analysis of the freiburg bonndorf bodensee fault zone fbbfz located at the external margin of the northern alpine molasse basin and extending into the crystalline black forest massif the structure and kinematics of this crustal scale fault zone are investigated by means of a regional analysis of locally mapped faults kinematic analysis of outcrop scale fractures and slip vector modelling the exceptional possibility of analysing the fault zone exposed from basement to cover allowed for an evaluation of interaction between precursory structures and subsequent deformation features the results of this study show that the crystalline basement structures exposed along the fbbfz had a strong imprint on the map scale fault pattern observable in the mesozoic and tertiary sequences kinematic analysis of outcrop scale fracture systems in the latter units yields evidence for local multi directional extension and strike slip faulting during miocene to recent times while these observations may evoke the interpretation of a multistage palaeostress history along the fbbfz slip vector modelling of a very well exposed fbbfz segment suggests that the various strain records can alternatively be explained by one single regional stress tensor and be related to superordinate deep seated strike slip deformation

early overpressuring in organic rich shales during burial evidence from fibrous calcite veins in the lower jurassic shales with beef member in the wessex basin uk field petrographic and geochemical analysis of fibrous calcite veins in the lower jurassic shales with beef member in the wessex basin was conducted to investigate the formation mechanism of the veins bedding parallel fibrous calcite veins including beef veins and tabular cone in cone structures are widespread in the black shales the calcite veins consist of subvertical fibrous crystals and a dark median zone the median zone contains scattered clays pyrite microcrystals skeletal fragments and amorphous organic matter the veins exhibit moderate carbon isotope values ranging from 1 515 to 2 732 the oxygen isotope composition ranges from 8 872 to 4 521 which is possibly too negative to reflect the primary porewater oxygen isotope signatures and indicates a porewater modification it is interpreted that the veins mainly derive carbonates from seawater inorganic carbon and bioclasts the veins formed as closed system hydraulic fractures in overpressured cells during sediment degassing in the methanogenic zone the shale beds with a high total organic carbon content could have generated abundant co 2 which may have resulted in either the cementing of the pores in the matrix or overpressure buildup the skeletal fragments provide a control on the spatial distribution of veins as nuclei for calcite precipitation from supersaturated pore fluids

paleogeography of the upper rhine graben urg and the swiss molasse basin smb from eocene to pliocene twenty paleogeographic maps are presented for middle eocene lutetian to late pliocene times according to the stratigraphical data given in the companion paper by berger et al this volume following a first lacustrine continental sedimentation during the middle eocene two and locally three rupelian transgressive events were identified with the first corresponding with the early rupelian middle pechelbronn beds and the second and third with the late rupelian serie grise fischschiefer and equivalents during the early rupelian middle pechelbronn beds a connection between north sea and urg is clearly demonstrated but a general connection between north sea urg and paratethys via the alpine sea is proposed but not proved during the late rupelian whereas in the southern urg a major hiatus spans early aquitanian to pliocene times early and middle miocene marine brackish and freshwater facies occur in the northern urg and in the molasse basin omm osm however no marine connections between these basins could be demonstrated during this time after the deposition of the molasse series a very complex drainage pattern developed during the late miocene and pliocene with a clear connection to the bresse graben during the piacenzian sundgau gravels during the late miocene pliocene and quaternary sedimentation persisted in the northern urg with hardly any interruptions the present drainage pattern of the rhine river from alpine area to the lower rhine embayment was not established before the early pleistocene