origin and evolution of oilfield waters in the tazhong oilfield tarim basin china and their relationship to multiple hydrocarbon charging events abstract we conducted a chemical and isotopic study of oilfield waters from ordovician limestone reservoirs in the tazhong oilfield tarim basin china to trace the origin and evolution of the waters and to demonstrate their possible relationship with hydrocarbon charging the elemental chemistry cl br so4 i k na ca mg and sr and multiple isotopic compositions d 18o 87sr 86sr and 129i i of the oilfield waters were determined the results show that these oilfield waters contain basinal brines that infiltrated in three stages along with a lesser contribution from meteoric water the meteoric water appears to have infiltrated downwards during the late silurian and carboniferous the earliest brine had very low i contents 50 mg l was derived from cambrian argillaceous source rocks and migrated upwards into ordovician reservoirs this stage was related to the main period of migration of crude oils out of the source rocks into reservoirs during the silurian and devonian both of these brines incorporated constant levels of fissiogenic 129i from the limestone reservoir rocks 11 8 47 0 atom l finally brine with very low i contents but higher 129i 106 491 atom l began to migrate upwards and infiltrate reservoirs given the relatively high fissiogenic 129i this stage may have occurred during the late cenozoic and was associated with migration of dry gas from the same source rocks our results combined with those of a previous study of other oilfields in the basin suggest that the evolutionary of oilfield waters can be used to constrain hydrocarbon accumulation events and both of which were ultimately controlled by regional tectonism and local geological factors

dating of pore waters with 129 i relevance for the origin of marine gas hydrates pore waters associated with gas hydrates at blake ridge in the atlantic ocean were dated by measuring their iodine 129 iodine ratios samples collected from sediments with ages between 1 8 and 6 million years ago consistently yield ages around 55 million years ago these ages together with the strong iodine enrichment observed in the pore waters suggest that the origin of iodine is related to organic material of early tertiary age which probably is also the source of the methane in the gas hydrates at this location

recycling of iodine in fore arc areas evidence from the iodine brines in chiba japan the distribution of iodine in the earth s crust is dominated by its accumulation in marine sediments if fluxes between terrestrial and marine compartments are considered however a significant imbalance exists between known sources and sinks of iodine we present here evidence from the fore arc area near chiba japan the world s largest brine iodine producing area that iodine is mobilized from marine sediments during the early stages of subduction based on detailed chemical analyses of 22 brines and 129i dating of 13 of these samples collected from the kazusa formation we show that iodine in these fluids is derived from organic rich marine sediments with a minimum age of 50 myr geochemical characteristics of the brines and the age of the iodine indicate that the iodine enrichment is caused by mobilization from subducting marine sediments and not by derivation from the host formation age 1 2 myr the direct return of iodine from marine sediments into the oceans during the subduction of oceanic plates could provide the missing link in the iodine cycle and be an important pathway also in the marine cycle of carbon

halogen and 129i systematics in gas hydrate fields at the northern cascadia margin iodp expedition 311 insights from numerical modeling we measured halogen concentrations and i 129 i ratios in five drilling sites of integrated ocean drilling program expedition 311 offshore vancouver island canada in order to identify potential sources of fluids and methane in gas hydrate fields iodine is dominated by organic decomposition and transports with fluids in reducing environments and the presence of the cosmogenic radioisotope i 129 t 1 2 15 7 ma allows the age determination of organic sources for iodine here we report halogen concentrations in 135 pore water samples i concentrations in 48 sediment samples and i 129 i ratios measured in a subset of 20 pore water samples most i 129 i ratios fall into a range around 500 x 10 15 corresponding to a minimum age of 25 ma and the lowest ratio of 188 x 10 15 t min 47 ma was observed at 208 m below sea floor mbsf in site 1326 these ages are considerably older than that of the local sediments in the gas hydrate fields and that of the subducting sediments on the juan de fuca plate indicating that old accreted sediments in the accretionary wedge contribute a significant amount of iodide and by association of methane to the gas hydrate occurrences a geochemical transport reaction model was applied to simulate the advection of deeply sourced fluids and the release of iodide bromide and ammonia in the host sediments due to organic matter degradation the model was first tested with data from two well studied areas ocean drilling program site 1230 peru margin and site 1245 hydrate ridge the model results for the expedition 311 sites indicate that the in situ release of young iodine is relatively minor in comparison to the contribution of migrating fluids carrying large amounts of old iodine from deep sources the comparison between the sites demonstrates that the total organic content has a strong effect on the rate of in situ iodine release and that lateral flows along fractures can have a significant influence on pore water chemistry especially at the cascadia margin the iodine results indicate that mobilization and transport of methane from sources in the upper plate of active margins is an important process which can also play a substantial role in the formation of gas hydrate fields

allochthonous sources of iodine and organic carbon in an eastern ontario aquifer regional geochemical characterization of groundwaters in a bedrock aquifer in the ottawa st lawrence lowlands of eastern ontario has identified an iodine i anomaly with values regularly excee

iodine 129 87sr 86sr and trace elemental geochemistry of northern appalachian basin brines evidence for basinal scale fluid migration and clay mineral diagenesis evidence for basin scale brine migration and clay mineral diagenesis in the northern appalachian basin was investigated using elemental and isotope 129i i 87sr 86sr geochemistry of formation waters collected from the middle to upper devonian section of the northern basin margin in western new york northwest pennsylvania and eastern kentucky one sample from each of the mississippian berea sandstone and the silurian medina sandstone were analyzed for comparison measured iodine ratios range between 28 to 1 890 10 15 and are anomalously high compared to cosmogenic iodine sourced from devonian age organic matter iodine 129 in the waters was largely derived from fissiogenic sources the spontaneous fission of 238u to produce 129i with estimated 129i i values up to 270 10 15 which occur locally in the organic rich shales there are three water samples that have values of 490 10 15 860 10 15 and 1 890 10 15 which are above the range for local fissiogenic 129i and may be accounted for by topographically driven basin scale fluid flow through a regionally high fissiogenic source relatively large uranium occurrences lie along the structural front of the appalachian basin in the blue ridge province and are situated within hypothesized flow paths parallel to the main compressional direction of the alleghanian orogeny estimated 129i i values for these uranium occurrences are in excess of 55 000 10 15 the strontium isotope composition and sr concentration of brines display a mixing trend between a highly radiogenic end member 0 7210 with low sr 51 mg l and a non radiogenic 0 7100 high sr 4789 mg l end member potassium and boron concentrations are notably depleted relative to evaporated paleozoic seawater the hypothesized source of appalachian basin brines the k rb values of formation waters are depleted relative to seawater values but in some cases are well above values indicative of water rock reactions the sr isotopic composition k and b depletion and intermediate k rb ratios are consistent with smectite diagenesis and paleo temperatures that are likely greater than approximately 150 c these temperatures may be high given the burial history of the study area and support the flow of formation waters from deeper within the basin the combined isotopic and elemental results of formation waters provide compelling evidence for basin scale fluid migration in the northern appalachian basin and are consistent with previously published evidence documented from the rock record including clay mineral diagenesis and ore deposition

influence of fracture system on the exploitation of building stones the case of the mondim de basto granite north portugal the most negative aspects in the exploitation of weathered granites as ornamental stones tend to be heterogenic coloration and fracturing therefore an accurate study is needed for a comprehensive evaluation of the granite resources during an exploration campaign this paper presents the results of the fracturing evaluation of a region located in north of portugal where the mondim de basto granite a stone with a high weathering degree is exploited the regional fracturing was evaluated from lineaments in aerial photos and then compared with local jointing in quarries the jointing in each quarry is characterized according to the strike and dip joint spacing and volumetric joint count two indices were proposed to facilitate the jointing comparison among quarries the joint space length ljs and joint set spacing sjs ljs is based on the sum of all the spacing values obtained perpendicularly to the strike direction sjs is computed based on the overall mean median spacing and on the number of joint sets observed in each quarry the most important joint sets in the subdivision of the rock mass were found not to be in accordance with the regional fracturing patterns highlighting the necessity of studying the fracturing at all scales

fracture surface energy of the punchbowl fault san andreas system the energetics of earthquake rupture slip weakening and rupture surface formation are poorly understood by measuring the energy associated with fracture damage along the punchbowl fault in the devil s punchbowl los angeles county park part of the san andreas system chester et al show that the fracture surface energy for rupture along a mature fault of this type accounts for only a small fraction of the energy released during large earthquakes as determined by seismologists this suggests that mechanisms such as melt lubrication and thermal pressurization are responsible for slip weakening fracture energy is a form of latent heat required to create an earthquake rupture surface and is related to parameters governing rupture propagation and processes of slip weakening1 2 3 fracture energy has been estimated from seismological and experimental rock deformation data4 5 6 7 8 yet its magnitude mechanisms of rupture surface formation and processes leading to slip weakening are not well defined8 9 10 here we quantify structural observations of the punchbowl fault a large displacement exhumed fault11 12 in the san andreas fault system and show that the energy required to create the fracture surface area in the fault is about 300 times greater than seismological estimates would predict for a single large earthquake if fracture energy is attributed entirely to the production of fracture surfaces then all of the fracture surface area in the punchbowl fault could have been produced by earthquake displacements totalling 1 km but this would only account for a small fraction of the total energy budget and therefore additional processes probably contributed to slip weakening during earthquake rupture

chemical and isotopic evidence for hydrogeochemical processes occurring in the lincolnshire limestone over 150 groundwater samples from the lincolnshire limestone have been analysed for ph major ions and 13c ratios where possible field eh and iodide concentrations were measured and methane concentrations were determined for 12 samples stable isotope ratios were determined for soil and rock carbonate samples a system of zonation allows the division of hydrogeochemical processes occurring in the aquifer the use of hydrochemical and isotope data in modelling exercises enables the re evaluation and possible enhancement of the understanding of hydrogeochemical processes the carbonate chemistry of outcrop groundwaters is explained by calcite saturation being achieved under open system conditions in the soil zone 13c ratios in the range 15 99 to 10 57 may be generated from a stoichiometric reaction with possible additional partial and or simultaneous exchange with soil co2 or carbonate the isotopic composition of soil carbonate shows the effects of precipitation from soil waters the incongruent dissolution of primary depositional limestone carbonate results in increasing magnesium and strontium concentrations and increasing 13c ratios for the groundwaters with flow down the hydraulic gradient as a result of incongruent dissolution secondary calcite may be precipitated onto fissure surfaces significant nitrate and sulphate reduction in non saline groundwaters is not supported by the results of hydrochemical and isotope modelling exercises however sulphate reduction and methane fermentation may be affecting the isotopic and chemical compositions of saline groundwaters sodium calcium ion exchange leads to limited calcite dissolution deep in the aquifer but the evolution of these groundwaters is confused by the uncertain effects of oxidation of organic carbon and mixing with a saline end member solution

iodine ages of pore waters at hydrate ridge odp leg 204 cascadia margin implications for sources of methane in gas hydrates hydrate ridge off the coast of oregon usa is a prime example for gas hydrate occurrences in active margin settings it is part of the cascadia margin and was the focus of ocean drilling program odp leg 204 which successfully recovered fluids from nine sites from the southern part of the ridge iodide concentrations in pore fluids associated with gas hydrates are strongly enhanced by factors up to 5000 compared to seawater which allows the use of this biophilic element as tracer for organic source regions we applied the cosmogenic isotope 129 i t 1 2 15 7 ma system to determine the age of the organic source formation responsible for the iodide enrichment in all sites at odp leg 204 129 i i ratios were found to decrease with depth to values around 250 10 15 corresponding to minimum ages of 40 ma but in several sites maxima in the 129 i i ratios point to the local addition of young iodide the results indicate that a large amount of iodide was derived from deep accreted sediments of eocene age and that additional source regions provide iodide of late miocene age the presence of old iodide in the pore waters suggests that fluid pathways are open to allow transport over large distances into the gas hydrate fields the strong correlation between iodide and methane in hydrate fields coupled with the similarity in transport parameters in aqueous solutions suggests that a large fraction of methane in gas hydrates also has old sources and is transported into the present locations from source regions of eocene age

influence of fracture geometry on shear behavior abstract laboratory research during the past 10 years has explained many critical links between the geometrical characteristics of fractures and their hydraulic and mechanical behavior one of the remaining research challenges is to directly link fracture geometry with shear behavior including behavior in response to changes in normal stress and shear direction this paper describes results from a series of shear tests performed on identical copies replicas of a natural granite fracture based on these tests we developed a method using image processing techniques to identify and quantify damage that occurs during shearing we find that there is a strong relationship between the fracture s geometry and its mechanical behavior under shear stress and the resulting damage using a three dimensional geostatistical model of the fracture surfaces we analyze the dependence of the size and location of damage zones on the local geometry and propose an algorithm for predicting areas that are most likely to be damaged during shearing in a given direction

shock wave radon surface signals associated with the upsurge of t p solitons in volcanic systems abstract the present paper introduces a theoretical model in order to describe ground surface anomalies of radon emissions as a volcano is perturbed from its quiescent steady state based upon modern thermo poro elasticity theory which has been found to successfully explain rock deformation fracturing these anomalies are considered as being due to the build up of a buried thermo mechanical source which in turn gives rise to the upsurge of a thermo mechanical or t p soliton this sort of fluid solitary wave travelling upwards through induced deformed fractured horizons locally perturbes a pre existing stationary radon concentration profile as the wave approaches the ground surface in order to model radon anomalies a diffusive convective transport equation of radon is adopted with darcy s velocity change controlled by the upsurge of the t p soliton as a result a new flow mechanism of radon emission is found which we call shock wave radon propagation some cases of volcanic eruptions which have been preceded and accompanied by anomalies in radon emissions are examined in the light of the model a reasonably good agreement in the pattern between the observed radon concentration changes and the theoretical curves is found a theoretical tool for volcanic surveillance is thus proposed corresponding to both an effort to shed more light on the correlations that may exist between geophysics and geochemistry of fluid emissions and the recognition through ground surface radon anomalies of subsurface thermo mechanical instabilities possibly preceding volcanic eruptions

sources and reservoirs of anthropogenic iodine 129 in western new york large quantities of iodine 129 have been released during nuclear weapons testing and from nuclear power and fuel reprocessing plants the distribution of this isotope was investigated in 110 surface water and soil samples from western new york where several potential point sources are located and other areas of north america to evaluate its sources transport pathways and reservoirs elevated 129i concentrations associated with a former reprocessing facility at west valley ny can be tracked to lakes erie and ontario via site drainage and for over 200 km via atmospheric transport while only a negligible signal is associated with active power plants in the area the results point to local reprocessing as the major source of 129i in western new york while bomb fallout constitutes less than 0 5 of the signal surface soil is the dominant reservoir for anthropogenic 129i in this region across north america 129i concentrations are lower than in western new york although still significantly higher than expected weapons fallout reprocessing releases are currently seen to be the major source for elevated 129i concentrations on a global scale in contrast to previous suggestions that most anthropogenic 129i was still derived from weapons fallout concentrations of 129i and iodine in surface reservoirs are generally found to be uncorrelated implying that natural iodine and anthropogenic 129i are not yet in equilibrium the results suggest that anthropogenic 129i is cycled between the atmosphere soil vegetation systems more rapidly than natural pre anthropogenic iodine

near lithostatic pore pressure at seismogenic depths a thermoporoelastic model summary a model is presented for pore pressure migration through a transition layer separating a meteoric aquifer at hydrostatic pressure from a deeper reservoir at lithostatic pressure this configuration is thought to be pertinent to the south iceland seismic zone sisz and to other tectonically active regions of recent volcanism where volatiles are continuously released by ascending magma below the brittle ductile transition poroelastic parameters are computed for basaltic rock the model is 1 d the fluid viscosity is temperature dependent and rock permeability is assumed to be pressure dependent according to a dislocation model of a fractured medium environment conditions are considered pertinent to basalt saturated with water at shallow depth case i and at mid crustal depth case ii if the intrinsic permeability of the rock is high no significant effects are observed in the pressure field but advective heat transfer shifts the brittle ductile transition to shallower depths if the intrinsic permeability is low the pressure dependent permeability can propagate near lithostatic pore pressures throughout most of the transition layer while the temperature is practically unaffected by advective contributions so that the rock in the transition layer remains in brittle condition geometrical parameters characterizing the fracture distribution are important in determining the effective permeability in particular if an interconnected system of fractures develops within the transition layer the effective permeability may increase by several orders of magnitude and near lithostatic pore pressure propagates upwards these modelling results have important bearings on our understanding of seismogenic processes in geothermal areas and are consistent with several geophysical observations in the sisz in connection with the two 2000 june m 6 5 earthquakes including i fluid pressure pulses in deep wells ii low resistivity at the base of the seismogenic layer iii low vp vs ratio and time dependent seismic tomography iv heterogeneity of focal mechanisms v shear wave splitting vi high b value of deep foreshocks vii triggered seismicity and viii radon anomalies

comparison of stable isotopes ratios of 36cl cl and 129i 127i in brine and deep groundwater from the pacific coastal region and the eastern margin of the japan sea abstract fifty three samples including brines associated with oil and natural gas reservoirs and groundwater samples from deep boreholes were collected from the pacific and japan sea coastal regions in japan the 129 i 127 i and 36 cl cl ratios and stable isotopes d and 18 o are compared to investigate differences related to the geotectonic settings of the two regions the d and 18 o data indicate that brine and groundwater from the pacific coastal region reflect mixing of meteoric water with connate seawater in the pores of sedimentary rocks on the other hand brine and groundwater from the japan sea coastal region have been hydrothermally altered in particular brines associated with petroleum accumulations at niigata and akita showed the same isotopic characteristics as fluids found in the kuroko deposits of the green tuff region in northeastern japan there is little difference in the 36 cl cl ratios in brine and groundwater from the pacific and japan sea coasts most brine and some deep groundwater except those from the pleistocene kazusa group have already reached the average secular equilibrium ratio of 9 9 2 7 10 15 for their mudstone and sandstone reservoirs there was no correlation between the 36 cl cl ratios and differences in geotectonic setting between the pacific and the japan sea coast the molar i br ratio suggests that the i in all of water samples was of biogenic origin the average 129 i 127 i ratio was 290 130 10 15 to 294 105 10 15 in both regions showing no relationship to the different geotectonic settings the uncontaminated brine and groundwater samples are likely to have retained the original 129 i 127 i ratios of marine i released from the old organic matter stored in sedimentary rock

fractal analysis of shear joint roughness the morphology of mortar replicas of two natural joints a granite and a schist made from the silicone rubber casts was characterized using a laser sensor profilograph to create three dimensional topographic maps before and after each shear test three successive direct constant normal load shear tests under three normal stress levels have been carried out on the joint replicas n 0 4 0 8 1 2mpa and n 0 4 0 8 1 4mpa for the schist and the granite joint replicas respectively based on geostatistical methods the variation in surface roughness in the course of shear tests is described using the fractal dimension d computation a roughness parameter srs and a degradation parameter dw were also defined and computed srs and dw quantify respectively the degree of joint surfaces roughness and the degree of degradation of sheared joint surfaces the variation of d as a function of n have been compared to the variation of srs as a function of n in the course of shear tests results indicate a good correlation between d and srs

application of a density volume fractal model for rock characterisation of the kahang porphyry deposit abstract this paper proposes a new approach called density volume d v fractal model to delineate rock characterisation in terms of density and rqd within the kahang cu mo porphyry deposit central iran the d v log log plot indicates that there are two density populations with a breakpoint at 2 7 t m 3 a correlation between results via the d v fractal with lithology models was carried out represent that the main lithology unit which is porphyritic quartz diorite pqd is associated with density 2 7 t m 3 which also has a strong correlation with rqd 70 a log ratio matrix is introduced to validate the d v fractal model for density with the main rock type pqd results illustrate that the density populations in rock types of the studied deposit observed a relationship between the fractal dimension in terms of density and the quality of the rocks based on rqd values which can be used for better understanding of rock quality for evaluation of the final pit slope geometry

global distribution and long term fate of anthropogenic 129i in marine and surface water reservoirs 1 since the advent of the nuclear age in the mid 1940s the mass of radioactive 129i t1 2 15 7 myr circulating in the earth s hydrosphere has increased nearly fortyfold from its natural background level of 140 kg nuclear fuel reprocessing has been by far the major contributor responsible for releasing 5400 kg of 129i primarily into the north atlantic ocean regional and global trends in the distribution of the 129i inventory are elucidated from an examination of more than 600 determinations of 129i in environmental samples from around the world because the major point sources are located in europe and the united states more than 99 of the present 129i reservoir is distributed in the northern hemisphere where both 129i concentrations and 129i i ratios in rivers lakes and shallow seawater are several orders of magnitude above the preanthropogenic background downwelling in the north atlantic presently provides a major sink for marine 129i however marine upwelling along the margins of the pacific will eventually return part of this anthropogenic input to the ocean surface where it will find its way back into surface waters and the atmosphere iodine 129 has a long half life 15 7 myr and consequently there is also the possibility that climate change will influence the dynamics of iodine transfer in surface reservoirs we model the effect of a collapse in thermohaline circulation and project a concentration increase of more than 3 orders of magnitude in shallow oceans over the 10 000 years that follow if nuclear reprocessing is to continue at the present rate

uncertainty quantification of structural and geotechnical parameter by geostatistical simulations applied to a stability analysis case study with limited exploration data abstract there are many uncertain factors impacting stability analyses of rock structures quantification of these factors significantly impact the engineering decision making process some of these factors are spatially distributed within the geological domain and the quantification of the spatial uncertainty is beneficial for stability analysis of the structure this paper proposes an integrated methodology for a stability analysis of rock structure by incorporating spatially varying factors this research models two key factors one categorical structural parameter fault zones and one continuous geotechnical parameter rock quality designation rqd two geostatistical simulation algorithms i e sequential indicator simulation and sequential gaussian simulation are applied to quantify the spatial uncertainty by generating multiple equiprobable simulation maps of fault zones and rqd values a slope stability analysis is performed by modeling the spatially varying fault zones and rqd the proposed method is validated using a synthetic data set the results from the synthetic data show the stability value of the synthetic data closely match with stability value calculated from simulated data finally the proposed method is applied to a slope stability analysis for an open pit mine design where limited exploration data is available geostatistically simulated rqd maps from the case study mine are analyzed to determine a safe slope angle of 44 for the open pit mining operation the proposed method can be applied for quantifying other geotechnical risk and integrated within any stability analysis framework

129i and 36cl in dilute hydrocarbon waters marine cosmogenic in situ and anthropogenic sources abstract the long lived halogen radioisotopes 129 i and 36 cl provide valuable information regarding the source of fluids in hydrocarbon systems and in localized areas where infiltration of younger meteoric water has occurred despite the utility of these two isotopes in providing time signatures for fluid end members considerable uncertainty remains regarding the interpretation of intermediate age waters in hydrologic systems these waters are likely the result of the combination of two or more halogen sources at some time in the past each with its own characteristic concentration and isotopic composition in order to unravel the evolution of these intermediate age waters the effect that infiltration of meteoric water has on the isotopic composition of older formation waters is modeled also evaluated is the effect that the timing of dilution has on 129 i and 36 cl signatures observed in the present specifically the hypothesis that halogen isotopic signatures imparted by the mixing of brine and meteoric waters early in the development of a sedimentary basin are quantitatively different from those imparted by the mixing of old brines with recent meteoric waters the modeled results are compared to previously published isotopic data from production wells in the fruitland formation coalbed methane system portions of the basin preserve enough of the original brine source to retain 129 i i ratios roughly recording the age of deposition of organic matter 73 76 ma even where some degree of dilution by meteoric water has occurred however the 129 i signatures of waters that presently contain less than 10 of the original formation water component indicate that mixing has occurred within the past 10 ma consistent with recently published 4 he data both 36 cl concentrations and 36 cl cl ratios show that waters containing more than 10 formation water are all in secular equilibrium with the host formation coals in contrast waters with less than 1 of the original formation water s cl content all have 36 cl cl ratios which are greater than secular equilibrium values indicating the migration of meteoric water into the coal formation more recently than 2 ma although 36 cl signatures in the fruitland formation are not significantly affected by anthropogenic input 129 i i ratios in a subset of samples that retain less than 1 of the initial formation water component suggest input of anthropogenic 129 i during the past 50 a

hot fluid migration in compressible saturated porous media summary solutions for heat and pressure transfer in compressible thermoporoelastic fluid saturated media are presented a hot and pressurized fluid reservoir is envisaged which comes into contact with a cold saturated half space the boundary between them is either pervious or impervious in the 1 d problem two coupled non linear equations are obtained for the temperature and pressure fields which are solved employing the self similarity method the thermally induced pressure in the half space is found to be generally relevant for low intermediate permeability media in the pervious boundary problem the thermal interaction gives rise to a striking effect in low permeability materials the induced pressure increases away from the boundary up to a maximum before declining to vanishingly small values further away a backflow is driven by the reverse pressure gradient from the point of maximum towards the reservoir the same effect is present although to a lesser extent in intermediate permeability materials saturated with liquid water under low boundary pressures in the impervious boundary problem the thermally induced pressure is relevant even for high permeability media the temperature field is affected by fluid flow only in the pervious boundary problem for high permeability media saturated with low viscosity fluids subjected to high overpressure over the boundary the conductive approximation which is obtained after neglecting the advection and the dissipation terms in the heat transfer equation is found to be applicable even to high permeability rocks under the impervious boundary conditions even if the previous conclusions are not strictly applicable to problems with different geometries the present solutions seem to bear important consequences on fluid migration mechanisms in volcanic areas where the backflow identified in low permeability media seems to be a viable mechanism for water enrichment by magma ascending through a dyke or emplaced in a magma chamber surrounded by colder water saturated low permeability rocks pore pressure and temperature can be also very effective in providing rock deformation depending on the rock type and boundary conditions either the pore pressure contribution or the thermal contribution may be dominant inflation episodes which are often observed in volcanic areas can be interpreted in a similar way thermoporoelastic effects might also be relevant in fault regions after the sudden frictional heating of water embedded between fault surfaces the theory may be also applied e g mc tigue 1986 to the modelling of areas of nuclear waste disposal

geochemistry of halogens in the milk river aquifer alberta canada abstract analytical data are presented for cl br and i on a regional scale for the milk river aquifer the three halides show strikingly similar spatial distributions and are highly correlated concentrations are low in the freshwater portions of the aquifer but increase by as much as two orders of magnitude along the margins however halide ratios reach nearly constant values moving down gradient suggesting the dominance of a common subsurface source for these ions ratios of cl i and cl br are less than those of seawater and fit an origin derived from the diagenesis of organic matter in the sediments halide ratios rule out leakage and or diffusion from the underlying colorado group as a major influence on the chemistry the favored hypothesis is altered connate seawater diffusing from low permeability units within the milk river formation as the primary source of salts this hypothesis of an internal source has important implications for solute sources in other aquifers affected by saline waters because it does not require the importation of a distant fluid the129i i ratio has a meteoric value in groundwater collected near the recharge area but ratios for downflow waters are only 8 70 of this value due to the 16 ma half life of129i these data indicate that most of the increase in dissolved i cannot derive from concentration of a meteoric source by ion filtration but must have a subsurface origin concentrations of129i producedin situ by spontaneous fission of238u attain measurable levels only in the oldest waters sampled ages 105a in which it may account for nearly 90 of the total dissolved129i concentration water ages based upon36cl cl data range up to 2 ma if uncorrected for any dilution by subsurface sources of dead cl if one assumes that the subsurface contributions of cl contribute at least 90 of total cl in the distal portion then the36cl based ages are reduced to 1ma somewhat greater than those estimated by hydrodynamic modeling

the value of iodide as a parameter in the chemical characterisation of groundwaters abstract brackish and saline groundwaters can severely constrain the use of fresh groundwaters their chemical characterisation is important in understanding the hydraulic conditions controlling their presence in an aquifer major ions are frequently of limited value but minor ions can be used iodide in groundwater is particularly significant in many environments due to the presence of soluble iodine in aquifer matrix materials iodide is found in groundwaters in parts of the english chalk aquifer in concentrations higher than are present in modern seawater its presence is considered as a indication of groundwater residence and is of use in the characterisation of fresh as well as saline waters under certain circumstances modern seawater intrusion into aquifers along english estuaries produces groundwaters which are easily identified due to iodide enrichment from estuarine muds in other environments iodide concentrations are of value in distinguishing between groundwaters in limestones and shaly gypsiferous rocks as shown by a study in qatar while in an alluvial aquifer study in peru iodide has been used to identify groundwaters entering the aquifer from adjacent granodiorites

tracing crustal fluids applications of natural 129i and 36cl the two cosmogenic isotopes 129i and 36cl have half lives and geochemical characteristics that make their application of interest in the tracing of crustal fluids oil field brines and geothermal fluids the focus of this review is to compare 129i data from volcanic fluids with those from mud volcanoes and gas hydrate locations associated with the same subduction zone in order to demonstrate that fundamentally different hydrologic systems are present in active margins whereas 129i i ratios in volcanic fluids are site dependent and show a relation to the ages of subducting marine sediments ratios in fore arc fluids are similar in all sites investigated and are independent of the ages of the host sediments and the age of the subducting slab volcanic fluids contain iodine transported in sediments from the trench to the main volcanic zone whereas iodine in fore arc fluids is derived from organic material stored in the upper plates of subduction zones

pre nuclear level of 129i in chinese loess paleosol sections a search for the natural 129i level for dating in terrestrial environments abstract due to its long half life 15 7 myr radioactive 129 i has great potential for dating geologic materials as old as 100 myr thus knowing the natural level of 129 i is crucial to dating applications the initial ratio of 129 i 127 i in the ocean has been quantified by a number of researchers who have reached a consensus value however the applicability of 129 i dating in the terrestrial environment remains problematic because the lack of an initial 129 i 127 i value in this work samples of loess paleosol sections from the chinese loess plateau clp were analyzed for 129 i 127 i aiming to provide an initial 129 i 127 i ratio that can be adopted for dating purposes in terrestrial environments a value of 2 0 1 0 10 11 for the 129 i 127 i ratio was found in two investigated loess paleosol sections from xifeng and luochuan china this ratio is one order of magnitude higher than the initial value reported for the marine environment alteration of the natural initial 129 i in the investigated samples due to the downward migration of anthropogenic 129 i and by excess fissiogenic 129 i from uranium was not supported consequently the 129 i 127 i ratio measured is considered to be a pristine value and the difference from that in the marine systems is attributed to an isotopic dilution effect

the morphology of a saline groundwater body its investigation description and possible explanation in many countries knowledge concerning the occurrence and behaviour of saline groundwaters is becoming even more vital as water resource and waste disposal projects become more sophisticated this paper outlines the approach adopted in and the result obtained from a study of saline water occurrence in an important united kingdom aquifer saline groundwater of concentration up to at least 100 g l 1 cl occurs as a layer of variable thickness below fresh groundwater in the permo triassic sandstones of the lower mersey basin of northwestern england as part of a general water resources study a detailed investigation of the morphology of the saline water body was undertaken using modern and historical chemical data surface geophysics borehole geophysics open hole depth sampling and borehole core porewater analysis it was found that cl concentrations at all sites show a pattern of steady increase to depths of at least 320 m the surface of the saline water body has a considerable topographic variation saline water occurs at highest elevations below the roughly east west trending mersey valley where it approaches ground level but declines in elevation both to the north and south in the north the saline interface meets the rising base of the sandstone sequence at a depth of around 280 m evidence from chemical and viscous flow analogue studies suggests that this ridged topography can be explained in terms of flushing and regional upconing in response to low groundwater heads in the mersey valley

hydrogeochemical analysis of salinization processes in the coastal aquifer of oropesa castellon spain the coastal aquifer of oropesa is affected by salinization processes undoubtedly associated with intense groundwater exploitation for agriculture supply the aquifer corresponds geologically to a tectonic depression with plioquaternary fill hydrogeologically this aquifer is detrital with intergranular porosity which receives substantial recharge from adjacent mesozoic aquifers contact with the sea in addition to the presence of cultivated soil requiring extreme exploitation of groundwater frequently give rise to processes of seawater intrusion the present research is an attempt to understand the saltwater intrusion in this aquifer using hydrochemical analyses of the behavior of certain minor ions that could help in the characterization process in the case of the oropesa sector groundwater salinization does not appear to be attributable solely to the intrusion of seawater but there are also anomalies related largely to the geology of the sector and its surroundings the type of recharge the hydrodynamic conditions in the specific area etc

2 d density and directional analysis of fault systems in the zagros region iran on a regional scale in this paper 2 d spatial variation of the frequency and length density and frequency length relation of large scale faults in the zagros region iran as a typical fold and thrust belt were examined moreover the directional analysis of these faults as well as the scale dependence of the orientations was studied for this purpose a number of about 8000 faults with l 1 0 km were extracted from the geological maps covering the region and then the data sets were analyzed the overall pattern of the frequency length distribution of the total faults of the region acceptably fits with a power law relation with exponent 1 40 with an obvious change in the gradient in l 12 0 km in addition maps showing the spatial variation of fault densities over the region indicate that the maximum values of the frequency and length density of the faults are attributed to the northeastern part of the region and parallel to the suture zone respectively and the fault density increases towards the central parts of the belt moreover the directional analysis of the fault trends gives a dominant preferred orientation trend of 300 330 and the assessment of the scale dependence of the fault directions demonstrates that larger faults show higher degrees of preferred orientations as a result it is concluded that the evolutionary path of the faulting process in this region can be explained by increasing the number of faults rather than the growth in the fault lengths and also it seems that the regional scale faults in this region are generated by a nearly steady state tectonic stress regime

determination of source ages and migration patterns of brines from the u s gulf coast basin using 129i abstract the long lived cosmogenic and fissiogenic isotope 129i has been applied to the study of source ages and migration patterns of oil field brines from the u s gulf coast basin 129 i i ratios were measured in sixty samples of saline formation water from depths of 660 4503 m in several oil fields in southeast texas south central louisiana and offshore louisiana comparisons between measured ratios and the decay curve for surface hydrospheric 129i result in minimum source ages much older than present host formation ages indicating vertical migration of brine from older deeper sources conservative corrections for a fissiogenic component due to spontaneous fission of 238u in the subsurface result in the following median source ages iberia field 55 ma port barre field 53 ma and eugene island blocks 316 and 330 55 ma pointing to wilcox group shales as source formations mesozoic sources cannot be ruled out due to the uncertainties in estimating the fissiogenic component some of the ratios measured in texas gulf coast brines show evidence of a greater fissiogenic component which indicates that the brines have resided in formations with locally high u concentrations

multi scale strainfield analysis using geostatistics investigating the rheological behavior of the hot variscan crust of the pyrenees axial zone the present study provides a quantitative way to analyze and interpolate strainfields from ductile fabric field measurements using geostatistics based on variogram analysis and kriging interpolations the developed methodology allows computing automatic cleavage and lineation trajectory maps at different scales from a same field structural dataset for the example provided by the hot variscan crust of the pyrenees the analysis of cleavage stretching lineations orientation and kinematic data document pure shear conditions recorded during convergence strain was vertically partitioned between an upper crust submitted to homogeneous thickening responding to n s orogen normal shortening and a hot and partially molten mid lower crust affected by horizontal longitudinal orogen parallel flow the emplacement of plutons and gneiss domes generated heterogeneities in the upper crust and induced strain localization into steep anastomosed transpressional shear zones flanking those structures the results show that geostatistics applied to structural geology are powerful tools for retrieving tectonic regimes of large orogenic segments by identifying and quantifying perturbations in the strainfields induced by protracted and potentially complex tectonic histories the variogram analysis also gives first order clues to evaluate whether the considered structural domains underwent single continuous ductile or polyphased brittle ductile deformation

a methodology for rock mass characterisation and classification to improve blast results abstract the rock mass description has been for a long time considered as a first step prior to all civil and mining projects involving rock mechanics problems in this paper a methodology is proposed which aims at the characterisation of the two rock mass components discontinuity network and rock matrix it was developed within the frame of the eu research project less fines proceedings of the second world congress on explosives and blasting technique 10 12 september 2003 prague czech republic pp 335 343 three quarry sites were chosen for the analysis el alto spain eibenstein austria and klinthagen sweden the discontinuity network was described using the 3d stochastic simulations of discontinuity networks using the simbloc program methodology several parameters assessing the density specific surface the interconnectivity interconnectivity index and the anisotropy anisotropy index and anisotropy vector of the discontinuity network as well as the 3d fractal dimension of the rock mass were introduced and evaluated for the three sites the rock matrix microstructure was characterised by the means of the experimental determination of several mechanical and physical parameters laboratory measurements performed on cores coming from the blasted blocks allowed a fine characterisation of this microstructure status the analysis of the results led to a precise characterisation of the differences between the sites and between the zones benches of a same site and to the classification of these zones according to the discontinuity network intensity and the rock matrix continuity moreover some implications could be pointed out with regards to the explosive energy types recommended for each rock mass class

underground production of radionuclides in the milk river aquifer alberta canada abstract most cosmogenic radionuclides that may be used to estimate groundwater ages in excess of 100 ka are also produced underground by in situ nuclear reactions radioactive equilibrium between in situ production and decay would be approached within such long residence times radionuclide production by in situ nuclear reactions within the groundwater and within its host rock has been calculated theoretically and compared with some measured radionuclide contents of the groundwater the fractional transfer of in situ produced 37 ar 39 ar and 222 rn from rock to groundwater necessary to account for the total measured groundwater contents were found to be similar although site specific the implications for radionuclide release mechanisms and for groundwater dating by the use of cosmogenic radionuclides including those which are applicable for very old groundwaters 36 cl 81 kr 129 i are discussed

origin of iodine in the anadarko basin oklahoma an 129i study iodine comes almost exclusively from organic matter in sedimentary basins and therefore can be used as a source indicator for hydrocarbons the long lived half life 15 7 m y cosmogenic and fissiogenic isotope 129i has been applied to tracing brine migration in the anadarko basin oklahoma because all of the likely source formations for i are paleozoic the cosmogenic 129i component has decayed to undetectable levels and all of the measured 129i is of fissiogenic origin comparison of 129i 127i ratios measured in 12 brines from the platform area of the anadarko basin with ratios determined for potential source rocks reveals that the woodford shale is the probable source formation for the extremely high i concentr tions observed in these brines if the woodford shale is the exclusive source for i the time of expulsion can be constrained to between 2 and 90 ma although this date is much later than most estimates of expulsion time derived from conventional methods a case is presented for more recent expulsion in the northern part of the basin which was the sample area

halogen geochemistry of the mcmurdo dry valleys lakes antarctica clues to the origin of solutes and lake evolution abstract we have determined the halogen and boron concentrations in the ice covered lakes of taylor valley antarctica to better establish the sources of salts and evolutionary histories of these unusual water bodies in addition we report on a series of 129 i measurements that were compared with previous 36 cl data that also help constrain the source of solutes and histories of the lakes the new data when put into context of previous work on these systems over the past forty years allow us to make the following conclusions the primary source of solutes to lake hoare the youngest of the lakes is the dissolution of marine aerosols and aeolian salts and the chemical weathering of dust on the glaciers the geochemistry of lake fryxell the brackish water lake is primarily dominated by the diffusion from a halite saturated brine at the sediment water interface and the recent infilling of the lake by glacier meltwater these waters have chemical weathering and marine aerosols components lake bonney has two distinct lobes whose hypersaline hypolimnia have different chemistries both of the lobes are remnants of ancient marine waters that have been modified by the input of weathering products this lake has also been modified by periods of cryogenic concentration when solutes have been lost via mineral precipitation thus the geochemistry of lake bonney owes its unusual geochemistry in part to variations in the climate in the taylor valley over at least the past 300kyr the 129 i data from the taylor valley are similar to those from fracture fluids in crystalline rocks from the northern hemisphere

on the propagation of nonlinear transients of temperature and pore pressure in a thin porous boundary layer between two rocks abstract the dynamics of transients of fluid rock temperature pore pressure pollutants in porous rocks are of vivid interest for fundamental problems in hydrological volcanic hydrocarbon systems deep oil drilling this can concern rapid landslides or the fault weakening during coseismic slips and also a new field of research about stability of classical buildings here we analyze the transient evolution of temperature and pressure in a thin boundary layer between two adjacent homogeneous media for various types of rocks in previous models this boundary was often assumed to be a sharp mathematical plane here we consider a non sharp physical boundary between two adjacent rocks where also local steady pore pressure and or temperature fields are present to obtain a more reliable model we also investigate the role of nonlinear effects as convection and fluid rock frictions often disregarded in early models these nonlinear effects in some cases can give remarkable quick and sharp transients all of this implies a novel model whose solutions describe large sharp and quick fronts we also rapidly describe transients moving through a particularly irregular boundary layer

hydraulic fracturing controlled dynamics of microseismic clouds 1 several dynamic processes related to propagation of hydraulic fracture modify the stress state in rocks and therefore they are relevant for triggering of microseismicity for instance these are the creation of a new fracture volume fracturing fluid loss and its infiltration into reservoir rocks as well as diffusion of the injection pressure into the pore space of surrounding rocks and inside the fracture using real data we show that some of these processes can be seen from features of spatio temporal distributions of the induced microseismicity especially the initial stage of fracture volume opening as well as the back front of the induced seismicity starting to propagate after termination of the fluid injection can be well identified and used for reservoir engineering

iodine budget in surface waters from atacama natural and anthropogenic iodine sources revealed by halogen geochemistry and iodine 129 isotopes abstract iodine enrichment in the atacama desert of northern chile is widespread and varies significantly between reservoirs including nitrate rich caliche soils supergene cu deposits and marine sedimentary rocks recent studies have suggested that groundwater has played a key role in the remobilization transport and deposition of iodine in atacama over scales of millions of years however and considering that natural waters are also anomalously enriched in iodine in the region the relative source contributions of iodine in the waters and its extent of mixing remain unconstrained in this study we provide new halogen data and isotopic ratios of iodine 129 i i in shallow seawater rivers salt lakes cold and thermal spring water rainwater and groundwater that help to constrain the relative influence of meteoric marine and crustal sources in the atacama waters iodine concentrations in surface and ground waters range between 0 35 m and 26 m in the tarapaca region and between 0 25 m and 48 m in the antofagasta region and show strong enrichment when compared with seawater concentrations i 0 4 m in contrast no bromine enrichment is detected 1 3 45 7 m for tarapaca and 1 7 87 4 m for antofagasta relative to seawater br 600 m these data coupled to the high i cl and low br cl ratios are indicative of an organic rich sedimentary source related with an initial fluid that interacted with meteoric water to produce a mixed fluid and preclude an exclusively seawater origin for iodine in atacama natural waters iodine isotopic ratios 129 i i are consistent with halogen chemistry and confirm that most of the iodine present in natural waters derives from a deep initial fluid source i e groundwater which has interacted with jurassic marine basement with variable influence of at least one atmospheric or meteoric source samples with the lowest isotopic ratios 129 i i from 215 to 1000 10 15 strongly suggest mixing between the groundwater and iodine storage in organic rich rocks with variable influence of volcanic fluids and pre anthropogenic meteoric water while samples with higher values 2000 93 700 10 15 indicate the input of anthropogenic meteoric fluid taking into account the geological hydrologic and climatic features of the atacama region we propose that the mean contribution of anthropogenic 129 i is associated with 129 i releases during nuclear weapon tests carried out in the central pacific ocean until the mid 1990 s 129 i i 12 000 10 15 this source reflects rapid redistribution of this radioisotope on a global scale our results support the notion of a long lived continental iodine cycle in the hyperarid margin of western south america which is driven by local hydrological and climate conditions and confirm that groundwater was a key agent for iodine remobilization and formation of the extensive iodine rich soils of atacama

a random field model for surface roughness and aperture of rock fractures present constitutive models for rock fracture behaviour require information concerning the fracture geometry on which the mechanical and hydraulic properties of the rock mass are greatly dependent in this paper measurements of rock fracture surfaces and aperture using a 3 d laser scanning technique are reported in order to check the validity of a fractal model for fracture geometry this formulation incorporates fractal descriptions of roughness angularity and aperture fractal patterns can be persistent if an increasing increment implies an increase in the next increment or anti persistent if increasing increments follows decreasing increments persistence and anti persistence are recognised as descriptors of the geometrical complexity of roughness and aperture the analysis of the data also shows that the fractal models apply until stationarity occurs for sufficiently large samples which behave as random variables these sample sizes are defined as stationarity thresholds of roughness and aperture moreover the study of the cross correlation between the asperity height and aperture provides the link between fracture roughness and aperture geometry a theoretical model of fracture aperture during shearing is developed and successfully compared with experimental and numerical studies reported in the literature

groundwater chemistry in southeast suffolk u k and its relation to quaternary geology abstract east anglia has a complex pleistocene geological history having been affected both by major changes in the level of the adjacent north sea and by glacial processes the resulting geology has a profound effect on the distribution of water chemistry in the chalk aquifer which underlies the pleistocene deposits a detailed study of the chemistry of the chalk groundwater including strontium fluoride and iodide as well as major elements has shown that this chemistry results from three phases of saline intrusion early pleistocene to modern and at least two periods of freshwater flushing climatic changes and erosional history were important in controlling flushing periods

controls on the 129i i ratio of deep seated marine interstitial fluids old organic versus fissiogenic 129 iodine iodine and its radioisotope 129i have been successfully used to trace the origin of pore waters in submarine fluid escape structures because of their close association with organic material in deeply buried sediments we report here halogen concentrations and 129i i ratios for fluids of five mud volcanoes sampled along an e w transect across the gulf of cadiz in the ne atlantic ocean concentrations of iodide and bromide increase consistently seaward accompanied by a decrease in 129i i ratios from 6490 10 15 to 663 10 15 the exceptionally high 129i i ratios at the near shore locations reflect the presence of fissiogenic 129i produced in situ by spontaneous fission of 238u within terrigenous sediments and released into pore water during clay mineral diagenetic processes the observed 129i i and halogen trends together with similar changes in 87sr 86sr ratios indicate a progressive seaward transition from inorganic terrigenous to organic marine fluid sources comparison of our results with literature data for varying geological settings reveals a general relationship between fissiogenic 129i radiogenic 87sr and the lithology or provenance of rocks and sediments respectively while 129i i ratios in continental rock hosted aquifers and terrigenous sedimentary systems are dominated by in situ production of fissiogenic 129i iodine isotopes in oceanic settings or volcanogenic marine sediments reflect the release of old iodine from deeply buried organic matter the gulf of cadiz represents the full transition between these continental and oceanic 129i i and 87sr 86sr end members this is the first systematic investigation of fissiogenic 129i production in marine sedimentary environments

the effect of fluid thermal expansivity on thermo mechanical solitary shock waves in the underground of volcanic domains this work is a further development of the modern thermo poro elasticity theory which has recently been applied to understand how fluid rock coupling dynamics related to unrest episodes in volcanic domains can both determine and occur with ground deformation and rock fracturing processes in particular by reformulating the energy equation one of the two nonlinear heat like equations upon which the thermo poroelasticity theory is based it is shown here how fluid thermal expansivity may influence fluid migration during its movement through subsurface volcanic porous per meable horizons with these new considerations it is found that a recent theory in which fluid rock coupling dynamics is interpreted in terms of thermal and mechanical solitary shock wave propagation remains valid however the natural time scale of the propagating wave is reduced and consequently darcy s velocity is increased as a result of fluid thermal expansivity

elliptical fracture network modeling with validation in datong mine china roof coal recovery rate and the performance of gas extraction are essentially controlled by the fractures within coal rock mass thus it is important to generate the accurate fracture network ahead of mining face in this study ten boreholes located differently from the 8212 working face of tashan mine in datong coal mining group china were drilled with the help of borehole video instruments the location orientation of each fracture and the fracture number of different intersection type on each borehole wall were mapped with the advancing of mining face these data were analyzed using the matlab toolbox rjns3d and dips to determine structural homogeneity zone to find the number of fracture sets that exist in the coal rock mass volume density frequency for each set and the probability distributions of orientation fracture size in 3 d sampling biases associated with orientation spacing were corrected during the process the constructed fracture networks were validated by comparing the observed mean spacing along normal vector of mean orientation for each set and the predict value on similar scanlines

rock mass rating spatial estimation by geostatistical analysis abstract this work aims to estimate the rock mass rating of 200 km 2 area of the italian central alps along san giacomo valley province of sondrio the regional geological setting is related to the pennidic nappe arrangement which is characterized by the emplacement of sub horizontal gneissic bodies separated by meta sedimentary cover units the resulting rmr map can be a useful tool to forecast the quality of outcropping rock masses as well as to derive their geomechanical behaviour almost 100 geomechanical field surveys have been carried out in the research area in order to characterize the outcropping rock masses afterwards rock mass quality indexes have been evaluated in each surveyed site in order to estimate the rock mass rating values in un sampled locations different geostatistical techniques kriging and simulations have been applied using both bi dimensional and almost three dimensional approaches the validation process shows that kriging tends to produce smoothened distributions while conditional simulations allow respecting local extreme values although geostatistical analysis reveals that geomechanical properties show spatial correlations it is to remind that rock mass quality is strongly related to its geological and structural history

using iodine isotopes to constrain supergene fluid sources in arid regions insights from the chuquicamata oxide blanket although iodine is rare in crustal settings previous studies have documented its occurrence in the supergene zones of base and precious metal ore deposits in arid environments in this report we present a novel application of the iodine 129 129i isotope tracer to iodine rich samples from the world s largest supergene cu profile at the chuquicamata deposit in northern chile where anomalous concentrations of this element have been reported all supergene marshite cui samples from chuquicamata and iodine rich soil above the mansa mina deposit have 129i i isotope ratios 190 560 10 15 that are significantly lower than those of surface waters i e 1 500 10 15 indicating that iodine was most likely derived from a reservoir of marine origin rather than a meteoric and or atmospheric source geochemical modeling shows that the long term dilution of iodinerich deep formation waters by meteoric water during the main stage of supergene alteration 40 10 ma resulted in fluid 129i i ratios that are within the range of mineral soil 129i i ratios observed at chuquicamata strongly suggesting that iodine was remobilized from the lower jurassic to mid cretaceous marine basement results from this study show that iodine isotopes can be successfully applied to trace the origin and nature of supergene fluids in iodine rich oxide blankets leach caps and soils above buried cu deposits and also to constrain the timescales of fluid circulation during supergene enrichment

age and speciation of iodine in groundwater and mudstones of the horonobe area hokkaido japan implications for the origin and migration of iodine during basin evolution abstract this paper reports the concentration speciation and isotope ratio 129i 127i of iodine from both groundwater and host rocks in the horonobe area northern hokkaido japan to clarify the origin and migration of iodine in sedimentary rocks cretaceous to quaternary sedimentary rocks deposited nearly horizontally in tenpoku basin and in the horonobe area were uplifted above sea level during active tectonics to form folds and faults in the quaternary samples were collected from the pliocene koetoi and late miocene wakkanai formations fms which include diatomaceous and siliceous mudstones the iodine concentration in groundwater up to 270 mol l is significantly higher than that of seawater with the iodine enrichment factor relative to seawater reaching 800 1500 the iodine concentration in the rocks decreases from the koetoi to wakkanai fms suggesting that iodine was released into the water from the rocks of deeper formations the iodine concentration in the rocks is sufficiently high for forming iodine rich groundwater as found in this area x ray absorption near edge structure xanes analysis shows that iodine exists as organic iodine and iodide i in host rocks whereas it exists mainly as i in groundwater the isotope ratio is nearly constant for iodine in the groundwater at 0 11 0 23 10 12 and it is higher for iodine in rocks at 0 29 1 1 10 12 giving iodine ages of 42 60 ma and 7 38 ma respectively some iodine in groundwater must have originated from paleogene and even late cretaceous fms which are also considered as possible sources of oil and gas in view of the old iodine ages of the groundwater the iodine ages of the rocks are older than the depositional ages implying that the rocks adsorbed some iodine from groundwater which was sourced from greater depths the iodine concentration in groundwater decreases with decreasing chlorine concentration due to mixing of iodine rich connate water and meteoric water a likely scenario is that iodine rich brine formed during the long term basin evolution from the cretaceous to quaternary and that this brine was diluted by mixing with meteoric water during uplifting and denudation of the area

influence of subduction zone settings on the origin of forearc fluids halogen concentrations and 129i i ratios in waters from kyushu japan abstract fluid migration in subduction zones is one of the key phenomena to understand the global mass transfer system while active volcanoes provide the most recognizable conduits for fluid flow in active margins the existence of a large number of active fluid seepages demonstrates that other forms of fluid release are also important in subduction zone settings the authors collected fluid samples from springs and wells across the forearc area in kyushu a southwestern island of japan covering hot spring activities associated with active volcanism and the median tectonic line mtl a major fault system present in the southwestern part of japan in order to determine sources of these fluids halogen concentrations as well as 129 i i and 36 cl cl ratios were measured in samples from several locations while cl concentrations of the forearc fluids in kyushu range between seawater and meteoric water value i concentrations are considerably higher than seawater value fluids in the miyazaki area are much higher in i and somewhat higher in br than waters in the oita area which is closely associated with the mtl the differences between those two areas are also pronounced in 129 i i ratios which range between 800 and 900 10 15 in the oita area and between 100 and 360 10 15 in the miyazaki area the 129 i i ratios obtained from the oita area are compatible with an i derivation from subducting marine sediments similar to findings from an earlier investigation of fluids collected from satsuma iwojima an active volcano south of kyushu island in the miyazaki area on the other hand i ages are too old to be derived from currently subducting marine sediments and point to a derivation from old organic rich materials in the upper plate of the forearc region the results demonstrate the presence of very different fluid systems in the forearc area of kyushu old ch 4 rich fluids dominate in the seaward side of the forearc while fluids close to the mtl and the quaternary volcanic front demonstrate derivations from subducting marine sediments the latter fluids in the mtl area probably are transported through the fractures associated with the fault activities suggesting that this fault system reaches the transition zone between upper and lower plates in this region

fluid inclusion and isotopic systematics of an evolving magmatic hydrothermal system the geysers california is the site of a long lived hydrothermal system that initially developed 1 5 2 m y ago in response to the intrusion of a hypabyssal granitic pluton although wells drilled into the geysers produce only dry steam fluid inclusion isotopic and mineralogic data demonstrate that the present vapor dominated regime evolved from an earlier and more extensive liquid dominated hydrothermal system circulation of these early fluids produced veins characterized by tourmaline biotite actinolite clinopyroxene within the pluton and adjacent biotite rich hornfels actinolite ferroaxinite epidote and epidote chlorite within the intermediate parts of the thermal system and calcite in the outer parts potassium feldspar and quartz are present in all assemblages pressure corrected homogenization temperatures and apparent salinities of fluid inclusions trapped in vein minerals range from 440 c and 44 wt nacl equivalent within the hornfels 600 m from the pluton to 325 c and 5 wt nacl equivalent at distances of approximately 1500 m from the intrusion we suggest that the shallow moderate salinity fluids are connate waters modified by water rock interactions while the high salinity fluids are interpreted as magmatic brines halite dissolution temperatures of inclusions in the hornfels and pluton indicate that the magmatic fluids were trapped at lithostatic pressures 300 900 bars in contrast homogenization temperatures of the connate fluids suggest trapping under hydrostatic pressures of less than several hundred bars whole rock 18o values of samples from the geysers display systematic variations with respect to depth location within the field and grade of alteration at depths below 610 m relative to mean sea level the 18o values are strongly zoned around a northwest southeast trending low located near the center of the steam reservoir as the pluton beneath the geysers is approached the 18o values decrease from approximately 14 per mil near the surface to 4 to 7 per mil within the hornfels the 18o values then increase to 8 to 10 per mil at the intrusive contact and thereafter vary little within the pluton calculated rock water fractionation factors suggest that temperature was the dominant control on the vertical decrease in the isotopic values of the reservoir rocks in contrast the increase in the 18o values within the hornfels suggest equilibration with an isotopically heavy fluid and or decreasing water rock ratios the formation of vapor dominated conditions is reflected in the abrupt appearance of low salinity 0 0 0 4 wt nacl equivalent fluid inclusions with homogenization temperatures near 265 c these inclusion fluids are thought to represent steam condensate that formed as the early liquid dominated system boiled off bladed calcite which is corroded in places and late stage clays provide mineralogic evidence of boiling and the formation of an acidic condensate in the upper part of the reservoir and in the overlying caprock at greater depths however clear mineralogic evidence of boiling is lacking the present vapor dominated regime at the geysers consists of two hydraulically connected steam reservoirs within the main steam reservoir pressures are vaporstatic and temperatures are nearly constant at 240 c beneath this reservoir in the northwestern third of the field temperatures as high as 342 c have been encountered wells drilled into this deeper reservoir discharge corrosive cl bearing steam

iodine 129 chronological study of brines from an ordovician paleokarst reservoir in the lunnan oilfield tarim basin abstract previous studies have shown that brines in an ordovician paleokarst reservoir of the lunnan oilfield in the tarim basin china are the product of mixing of paleo evaporated seawater in the east with paleometeoric waters in the west in order to put time constraints on the brine and related hydrocarbons in this field 10 brine samples were collected for which the iodine concentrations and 129 i i ratios were measured and discussed the iodine concentration 3 70 31 2 mg l and the 129 i i ratio 189 897 10 15 show that the iodine in the paleoseawater and meteoric water mw had different origins and 129 i characteristics the paleoseawater has a high iodine content 31 mg l indicating that iodine was introduced into the reservoir along with thermally generated hydrocarbons possibly in the cretaceous from the caohu sag in the eastern area based on consideration of all possible origins of iodine and 129 i in the brines it is suggested that the meteoric water maintained its initial iodine content 0 01 mg l and 129 i i ratio 1500 10 15 whereas the iodine enriched paloseawater ipsw exhibited a secular 129 i equilibrium n sq 39 atom l as a result of fissiogenic 129 i input in the reservoir over a long period of time the model of brine evolution developed on that basis confirmed that meteoric water entered the reservoir in the miocene at about 10 ma and partially mixed with the iodine enriched paleoseawater the movement of meteoric water was facilitated by faults created during the himalayan orogeny then became more dense after dissolving paleogene halite and infiltrated into the reservoir at high pressure the iodine and 129 i concentration in the brine contains information about the path and history of the fluid in the reservoir this may be useful in oil exploration since the movement of water was to some extent related to hydrocarbon migration

iodine dating of pore waters associated with gas hydrates in the nankai area japan the nankai hydrate field japan is an example of gas hydrate deposits associated with an active subduction zone in order to determine the origin of gas hydrates in this area 129i i ratios together with halogen concentrations were measured in a set of pore water samples collected from two boreholes in the nankai hydrate field iodine concentrations are between 100 and 230 m i e strongly enriched compared to seawater while cl concentrations were found to be close to that of seawater except for one sample 129i i ratios are between 180 and 520 10 15 giving minimum ages between 24 and 48 ma because these ages are considerably older than present host sediments 2 ma and subducting marine sediments 21 ma in this area iodine and by association methane in the gas hydrates must have been derived from source formations located in the continental side of the subduction zone the results do not support derivation of gas hydrates from present host sediments or currently subducting sediments but could be related to release and long time recycling of fluids from marine formations of early tertiary age

determination of natural and anthropogenic 129i in marine sediments sup 129 i concentrations in two sediment cores from the continental slope near cape hatteras were determined with tandem accelerator mass spectrometry tams the natural sup 129 i sup 127 i ratios in these cores are approximately 10 sup 12 the input of anthropogenic sup 129 i has increased this ratio to values close to 10 sup 10 at the surfacee of the sediments the observed natural level of sup 129 i is about two orders to magnitude above the current detection limit with tams which opens up to possibility for applications of sup 129 i in the marine system such as dating of sediments and crude oils and tracing of slow water movement in sediments

isotopic character and origin of brine leaks in the avery island salt mine south louisiana u s a twelve brine leaks in the avery island salt mine have the isotopic signature of meteoric waters and are isotopically similar to shallow wells around the salt dome the mine leaks are interpreted as meteoric waters which have penetrated the salt one leak at the 275 m 900 ft level is drastically enriched in 18o relative to the other waters this water is similar to 18o rich waters in other gulf of mexico coast salt domes and is interpreted as formation water which became incorporated in the salt during diapiric rise of the dome while water encounterd in other salt domes is primarily formation water the water encountered in the avery island salt is primarily meteoric this may be related to the shallow depth of the mine close proximity of the salt top to the surface absence of caprock and or duration and technique of mining

directional semivariogram analysis to identify and rank controls on the spatial variability of fracture networks abstract in this study the directional semivariogram is deployed to investigate the spatial variability of map scale fracture network attributes in the paradox basin utah the relative variability ratio r is introduced as the ratio of integrated anisotropic semivariogram models and r is shown to be an effective metric for quantifying the magnitude of spatial variability for any two azimuthal directions r is applied to a gis based data set comprising roughly 1200 fractures in an area which is bounded by a map scale anticline and a km scale normal fault this analysis reveals that proximity to the fault strongly influences the magnitude of spatial variability for both fracture intensity and intersection density within 1 2 km additionally there is significant anisotropy in the spatial variability which is correlated with trends of the anticline and fault the direction of minimum spatial correlation is normal to the fault at proximal distances and gradually rotates and becomes subparallel to the fold axis over the same 1 2 km distance away from the fault we interpret these changes to reflect varying scales of influence of the fault and the fold on fracture network development the fault locally influences the magnitude and variability of fracture network attributes whereas the fold sets the background level and structure of directional variability

iodine in major danish aquifers iodine in groundwater can have direct importance for human dietary iodine intake in areas where drinking water is of groundwater origin as in denmark knowledge on the sources and processes for the varying iodine concentrations in groundwater is of utmost importance for understanding the variation in iodine intake of the population via drinking water the aim of this study was to characterize groundwater with elevated iodine concentrations and to investigate the sources and processes controlling natural iodine speciation and concentration at four study sites in denmark with postglacial sandy quaternary sandy and cretaceous limestone aquifers analyses included iodide i iodate io3 total iodine ti major ions and stable h and o isotopes dissolved organic iodine doi was calculated by subtracting i and io 3 from ti a diagram of stable 18o and 2h isotopes in danish groundwater was compiled in order to interpret the groundwater iodine geochemistry groundwater had ti concentrations from 5 to 14 500 g l iodine speciation reflected the prevailing neutral to alkaline and reduced conditions at the investigated sites with domination of i and doi correlated with dissolved organic carbon we found three different explanations for elevated ti concentrations at the four danish sites 1 leaching from soil enriched in iodine due to atmospheric deposition and proximity to the sea 2 influence from the marine origin of the aquifer sediment due to desorption of iodine from iodine enriched organic matter or minerals and 3 influence from residual saline water due to upward advective or and diffusive transport of iodine

variations in 129i 127i ratios in recent marine sediments evidence for a fossil organic component abstract the value of the pre bomb 129 i 127 i ratio in the hydrosphere is important for the use of this isotope system for dating and tracing purposes in order to determine this value and to examine spatial variability 129 i 127 i ratios were measured in 25 sediment samples from five cores taken at geographically distinct coastal areas the results indicate a pre anthropogenic 129 i 127 i ratio of 1500 10 15 in good agreement with values derived from previous sediment and groundwater studies results from shallow sediments show that the layer of bioturbation is dominated by the addition of anthropogenic 129 i the good agreement between results for this layer from different cores supports the understanding that marine iodine is isotopically homogeneous and associated with organic material which is actively remineralized at the sediment water interface lower ratios down to 354 10 15 corresponding to an age of 32 5 ma and larger variations than expected were found in sections of the cores below the layer of bioturbation these observations can be explained by the presence of refractory fossil organic material transported by rivers to the sediments from uplifted continental shales the results suggest that marine iodine is present in two forms a labile component which is isotopically homogeneous and a refractory component which is associated with kerogen or other fossil organic compounds whose 129 i 127 i ratio reflects the age of these compounds 129 i 127 i ratios can be used to identify and date fossil organic material in recent sediments the presence of which can alter the assumptions underlying models of the global carbon cycle

origin of hydrocarbons in the green tuff region of japan 129i results from oil field brines and hot springs in the akita and niigata basins abstract the akita and niigata basins are part of the green tuff region of honshu japan which hosts major occurrences of oil and gas and of hydrothermal sulfide sulfate kuroko deposits the green tuff formation is associated with the opening of the japan sea which occurred in the early miocene and was accompanied by large scale volcanic activities we measured halogen concentrations and 129i i ratios in oil and gas field brines and hot springs in order to determine the origin of iodine and indirectly of hydrocarbons in this area and their association with geological processes during the formation of the japanese island arc based on the concentration of iodine these samples fall into three categories type a i 190 m type b 150 m i 90 m and type c i

origin and age of pore waters in an actively venting gas hydrate field near sado island japan sea interpretation of halogen and 129i distributions abstract a gas hydrate field with highly active venting of methane was recently found near sado island in the eastern japan sea piston cores were collected from active venting sites and nearby locations in the umitaka spur joetsu knoll area during two cruises in 2004 ut04 and 2005 ky05 08 we report here halogen concentrations and 129 i i ratios in pore waters associated with gas hydrates from these expeditions the strongly biophilic behavior of i and to a lesser degree of br together with the presence of the long lived iodine radioisotope 129 i allow evaluation of potential source materials for methane in gas hydrate systems depth profiles of all three halogens particularly the very rapid downward increases of br and i concentrations strongly suggest input of deep fluids enriched in br and i but the profiles also display the effects of gas hydrate formation and dissociation although the 129 i i ratios are modified by 129 i from seawater and sediments at shallow depth likely ratios of the deep fluids are estimated to be between 400 10 15 and 600 10 15 equivalent to a late oligocene to early miocene age ages in the active methane venting sites typically are closer to the old end of this range than those in the reference sites this age range suggests that the methane associated with venting and gas hydrate formation in this area is derived from organic materials accumulated during the initial opening of the japan sea the umitaka spur joetsu knoll gas hydrate field demonstrates the movement of deep fluids associated with the release of significant amounts of methane from the seafloor processes which might be important components of mass transfer and carbon cycle in the shallow geosphere

denitrification in a major limestone aquifer abstract the chalk aquifer of eastern central england is seriously affected by nitrates leached from agricultural land and like many similar aquifers its future as a potable resource must depend considerably on the nature and rates of denitrification the regional distribution of nitrate supports a viewpoint based on thermodynamic criteria that denitrification is actively occurring and that the problem will be short lived more detailed considerations based on major ion and environmental isotope data however indicate that denitrification is not significant and that the apparent lowering of nitrate concentration from 10 to 1 no 3 n in the apparent direction of flow is due primarily to mixing between waters of different origins presence of reduced nitrogen species is possible evidence of denitrification in some older waters 4000 yr b p it is concluded that denitrification can not be relied upon to reduce elevated concentrations of nitrate in modern recharge waters

weathering profile of the cerro de maimon vms deposit dominican republic textures mineralogy gossan evolution and mobility of gold and silver abstract cerro de maimon in the central dominican republic is currently the only vms deposit under production in the caribbean region it is hosted in the maimon formation of early cretaceous age which is part of the oldest and chemically most primitive island arc in the caribbean from bottom to top this deposit can be divided into i a primary sulfide zone ii a supergene enrichment zone and iii an oxidized zone this study reports new data on the textural and mineralogical characteristics of the oxidized zone gossan leached capping zone with emphasis in the au ag bearing phases the mineral paragenesis of the oxidized zone is essentially composed of goethite hematite quartz and barite botryoidal cellular and brecciated textures can be distinguished botryoidal and brecciated textures dominate in the upper parts of the oxidized zone whereas cellular textures are more common in the intermediate and lower parts however the weathering profile is very heterogeneous the leached capping profile shows evidence of both transported and indigenous gossans gold in the oxide paragenesis is extremely pure 99 au suggesting that chemical refining took place silver occurs mainly as iodargyrite agi and minor agbr agcl in botryoidal aggregates particles of au ag alloy in the primary mineralization exposed to a weathering environment can be leached and transported by various agents chemical and biochemical that may exist simultaneously in the presence of halides gold and silver can be leached and transported in a wide range of ph eh conditions especially if iodine is present silver is leached more rapidly and over a broader range of ph eh conditions and is preferentially transported as iodine complexes than other halides the presence of iodargyrite in the cerro de maimon gossan fully developed under tropical conditions suggests that this mineral cannot be considered an indicator of extremely arid environments as typically claimed by many authors iodargyrite occurrence would rather point to the presence of saline halide rich groundwater in oxide deposits

129i and 36cl concentrations in waters of the eastern clear lake area california residence times and source ages of hydrothermal fluids abstract the clear lake area of northern california is the location of hot spring activity some of which is associated with the formation of au and hg deposits we measured 129 i i and 36 cl cl ratios in nine warm springs formation springs six cold springs with elevated levels of cl and i mineral springs and five springs of recent meteoric origin dating of the i in the formation waters indicated that sources of i in these waters are formations with minimum ages between 60 and 80 ma this age range is in good agreement with the ages of the franciscan complex and the great valley sequence the dominant formations in this area because the mineral waters are essentially formation waters diluted with meteoric water i in these waters is of the same origin residence times of the waters were calculated based on the build up of129i and 36cl as a consequence of the presence of u and th in the crust the residence time of the formation waters in the great valley sequence the location for most of these springs was probably not longer than 84 000 yr the concentrations found for 36cl and 129i in the mineral waters indicate that these waters have residence times of similar magnitude in formations such as the franciscan complex or the clear lake volcanics which have slightly higher levels of u and th than the great valley sequence

natural iodine 129 as an environmental tracer abstract iodine 129 t 1 2 16 my is a naturally occurring tracer which can be used to study hydrologic and geologic processes on time scales up to 100 my the pre bomb atmospheric ratio 129 i i should have been constant in time and space and is the starting value in ground water recharge subsequent ratio changes in ground water should be determined by isotope contributions from three sources recharge water iodine leached from the formation and in situ uranium fission the mathematical expression of these time dependent processes forms the basis for dating and tracing applications the expected behavior of natural 129i in ground water is compared to results from field studies ground water samples from the great artesian basin australia provide an estimate of the atmospheric equilibrium ratio 6 10 13 down gradient changes in water up to 1 my old suggest that subsurface production can be significant the usefulness of 129i as an indicator of brine source and age is verified in brines collected in and around louisiana salt domes the method leads to ages of 7 and 9 my for two brine pockets trapped within jurassic salt and 32 to 40 my for oil field brines in miocene sands adjacent to the domes the results demonstrate the capability of tandem accelerator mass spectrometry to measure as few as 107 atoms of 129i in 10 mg i with 10 precision although such atom sensitivity can be achieved otherwise the accelerator technique is necessary to measure naturally low pre 1945 cosmogenic isotope ratios

uranium series isotopes in the groundwater of the permo triassic sandstone aquifer lower mersey basin u k abstract an investigation of u and th series isotopes in rock and groundwater samples from a permo triassic sandstone aquifer of northwest england is described the groundwaters sampled range in age and composition from fresh and modern to highly saline and ancient with at least two sources of salinity highest u and th concentrations are present in the mudrock beds within the sandstone sequences the 234u 238u and 226ra 230th rock activity ratios suggest that saline waters were once much more extensive throughout the aquifer and have been flushed by several volumes of fresh groundwater since the last glaciation uranium contents and activity ratios confirm that the isotope signatures observed in most of the sampled groundwaters are not the result of simple conservative mixing relations between high u saline waters and low u fresh groundwaters but that the isotopic content of the matrix the matrix mineralogy and fabric the redox conditions the salinity and possibly the carbonate chemistry are all important petrographic studies have demonstrated the multiphase nature of the sandstones and although the isotopic signatures are consistent with the origins of the sampled water as concluded from other hydrochemical and hydrogeological data quantitative modelling of the processes involved is limited by lack of details of u bearing phases pore architecture and the chemistry of u in high ionic strength solutions however ra concentrations are controlled by sorption processes and ra is shown to be mobilised under saline conditions the mechanisms of rn release from the aquifer matrix are reviewed and a rn release factor of 0 11 is calculated this value is believed to be inappropriate as a measure of the recoil supply of the longer lived rn precursors in the u decay series

3d hybrid tectono stochastic modeling of naturally fractured reservoir application of finite element method and stochastic simulation technique abstract simulation of naturally fractured reservoirs offers significant challenges due to the lack of a methodology that can utilize field data to date several methods have been proposed by authors to characterize naturally fractured reservoirs among them is the unfolding folding method which offers some degree of accuracy in estimating the probability of the existence of fractures in a reservoir also there are statistical approaches which integrate all levels of field data to simulate the fracture network this approach however is dependent on the availability of data sources such as seismic attributes core descriptions well logs etc which often make it difficult to obtain field wide in this study a hybrid tectono stochastic simulation is proposed to characterize a naturally fractured reservoir a finite element based model is used to simulate the tectonic event of folding and unfolding of a geological structure a nested neuro stochastic technique is used to develop the inter relationship between the data and at the same time it utilizes the sequential gaussian approach to analyze field data along with fracture probability data this approach has the ability to overcome commonly experienced discontinuity of the data in both horizontal and vertical directions this hybrid technique is used to generate a discrete fracture network of a specific australian gas reservoir palm valley in the northern territory results of this study have significant benefit in accurately describing fluid flow simulation and well placement for maximal hydrocarbon recovery

salinization properties of a shallow groundwater in a coastal reclaimed area yeonggwang korea the need for more agricultural or residential land has encouraged reclamation at the coastal areas of korea since 1200 ad approximately the groundwaters of these reclaimed areas could be expected to reveal hydrogeochemical properties different from those of areas directly affected by seawater intrusion the purpose of this study therefore was to examine the salinization of shallow groundwater in a coastal reclaimed area and to identify the effect of land reclamation on groundwater quality major cations and anions iodide total organic carbon d 18o and 13c were measured to assist the hydrogeochemical analysis chloride d and 18o data clearly show that the na cl type water results from mixing of groundwater with seawater in particular the d and 18o of ca mg cl no3 type groundwaters are close to the meteoric water line but na cl type waters enriched in chloride are 18o enriched with respect to the meteoric water line meanwhile carbon isotopic data and i cl ratios strongly suggest that there are various sources of salinity the 13c values of na cl type groundwaters are generally similar to those of ca mg cl no3 type waters which are depleted in 13c with respect to seawater i cl ratios of na cl type groundwater are 10 100 times higher than that of seawater because the reclamation has incorporated a large amount of organic matter it provides optimum conditions for the occurrence of redox processes in the groundwater system therefore the salinization of groundwater in the study area seems to be controlled not only by saltwater intrusion but also by other effects such as those caused by residual salts and organic matter in the reclaimed sediments

hydrogeochemical effects of groundwater mining of the sierra de crevillente aquifer alicante spain the groundwater mining of the crevillente aquifer southeastern spain has resulted in the progressive deterioration of water quality with particularly significant increases in chloride sulfate and sodium the possibility of a vertical hydrochemical zoning is deduced that would require examining the importance of the geometry and lithology evaporitic materials in the salinization process the time of water rock contact residence time and dilution by infiltration of rainwater also influences the hydrogeochemistry of the aquifer the hydrochemical data are useful in defining the conceptual model of the aquifer completely karstified with relative homogeneity

129i anthropogenic budget major sources and sinks data are presented here on the anthropogenic 129i inventory in regions that have been strongly affected by releases from european reprocessing facilities which to the authors knowledge presently account for 90 of the global isotope source in the earth s surface environment the results show that 90 of the isotope inventory occurs in marine waters with the nordic seas and eurasian basin of the arctic ocean containing most of the 129i within the terrestrial environment of europe soils contain the largest part of the isotope inventory however the inventory of the terrestrial system did not provide clues on the most plausible atmospheric source of 129i to europe thus supply from both gaseous and marine releases is proposed the sum of the total inventory in both the marine and terrestrial environments did not match the estimated releases this imbalance is likely to relate to unconstrained inventory estimates for marine basins irish sea english channel and north sea close to the facilities but also to the occurrence of 129i in the biosphere and possible overestimated releases from the nuclear reprocessing facilities there is no doubt that the available data on 129i distribution in the environment are far from representative and further research is urgently needed to construct a comprehensive picture

hydrogeology of sedimentary basins abstract hydrogeologic environments in sedimentary basins are as variable as are the different types of basins important hydrologic characteristics can be used to distinguish the different types of basin 1 the topographic setting as determined by the geologic and structural history of the basin 2 permeability distribution within the basin and 3 potential energy distributions and flow mechanisms these parameters control residence times of waters rates and directions of saline groundwater flow and the origin and chemical composition of the saline waters the gulf coast and palo duro basins texas exemplify two end member types of sedimentary basins the gulf coast basin is a relatively young tertiary age basin which is presently compacting fluid movement is from the overpressured undercompacted sediments up the structural dip or up fault zones into the hydrostatic section natural fluid pressures are either hydrostatic or overpressured the palo duro is an older paleozoic age basin that has been tectonically uplifted fluid flow is gravity driven from topographically high recharge areas to discharge in topographically low areas fluid pressures are subhydrostatic fluids discharge more easily than they are recharged not all flow is derived by a simple recharge discharge model brines may flow from other basins into the palo duro basin and waters may discharge from the palo duro basin into other basins areal differences in the chemical composition of the basin brines may be the result of different origins

sources sinks and long term cycling of iodine in the hyperarid atacama continental margin abstract the atacama region in northern chile hosts the driest desert on earth and is the world s premier iodine production province the origin of iodine enrichment in atacama is controversial and fundamentally different processes have been invoked over the years that involve marine eolian and more recently deep sedimentary fluid and groundwater sources as a result of the very limited geochemical iodine data in atacama and the western south american margin the origin of iodine enrichment in this region still remains elusive in this study we present a comprehensive survey of iodine concentrations and isotopic ratios 129i i of different reservoirs in the atacama desert of northern chile including nitrate soils supergene copper deposits marine sedimentary rocks geothermal fluids groundwater and meteoric water nitrate soils along the eastern slope of the coastal cordillera are found to have mean iodine concentrations of at least three orders of magnitude higher than the mean crustal abundances of 0 12 ppm with a mean concentration of 700 ppm soils above giant copper deposits in the central depression are also highly enriched in iodine 100 s of ppm range and cu iodide and iodate minerals occur in the supergene enrichment zones of some of these deposits further east in the precordillera jurassic sedimentary shales and limestones show above background iodine concentrations the latter averaging 50 ppm in the southern portion of the study area the highest iodine concentrations in fluids were measured in groundwater below nitrate soils in the coastal range 3 5 10 ppm and in geothermal waters 1 3 ppm along the volcanic arc although highly variable the iodine isotopic ratios 129i i of jurassic marine sedimentary rocks 300 600 10 15 nitrate soils 150 1500 10 15 and waters 215 10 15 are consistently low

characterizing block geometry in jointed rockmasses the intersection of discontinuities in a jointed rockmass creates in situ blocks of variable three dimensional 3d geometry the size and shape of rock blocks in a rockmass assembly have a dominant influence on the engineering properties of a rockmass and control for example the failure geometry of a rock face and the optimum associated support and surface restraint strategy the distribution of block volumes within a rockmass can be effectively analyzed and communicated using a cumulative volume distribution curve integrated with this analysis a methodology has been developed to characterize the shape and volumetric shape distribution of rock blocks in 3d models of jointed rockmasses the proposed block shape characterization method takes into account two factors the first describes the shortening of the minor principal axis of the block while describes the elongation of the major axis when merged with the block volume distribution the block shape characterization method can effectively describe and classify both the size and shape distributions of any jointed rockmass and is not limited to orthogonal blocks or hexahedra this methodology can classify any polyhedra and has been developed and calibrated based on synthetic joint data and simulated block assemblies a demonstration is given of its effectiveness in characterizing block geometries in the field using mapped fracture data

estimating the intensity of rock discontinuities this paper presents an approach for estimating the intensity of discontinuities and formulating intensity and orientation as a fracture tensor specifically the size distribution and the number of discontinuities are estimated first from which the fracture tensor is then derived discontinuity size distribution is inferred from the trace data sampled in circular windows by using a general stereological relationship between the true trace length distribution and the discontinuity diameter distribution assuming circular shaped discontinuities because the measured trace lengths are biased a method is proposed to estimate the true trace length distribution for circular window sampling circular window sampling has the advantage of automatically eliminating the orientation bias when estimating the true trace lengths a method is then presented with which the total number of discontinuities in an objective volume can be estimated from the number of discontinuities observed in normal size boreholes and using the inferred discontinuity diameter from the circular window sampling on the rock surface with the derived size distribution and number of discontinuities the intensity of discontinuities which is the total surface area of discontinuities per unit volume can then be calculated and included in a new definition of a fracture tensor an application of the approach to analyze simulated discontinuities produces satisfactory results

evolution of pennsylvanian late carboniferous peat swamps of the ruhr basin germany comparison of palynological coal petrographical and organic geochemical data abstract this study focuses on the reconstruction of the environment during peat swamp development eight coal and sedimentary organic rock bearing seam successions were examined all belonging to the duckmantian pennsylvanian late carboniferous 410 samples were analysed with coal petrographical methods 155 of these also by palynological methods in addition on 55 samples organic geochemical investigations were carried out with respect to n alkanes and iso alkanes the established coal petrographical parameters gelification index gi tissue preservation index tpi groundwater index gwi and vegetation index vi were used to characterize different periods of peat swamp development furthermore the new index wci water cover index was introduced to reflect water level conditions by using the ratio between hydrophilous hygrophilous and mesophilous plants in this study the index is based on palynological data but can be equally applied when quantitative macrofloral counts are available gi versus tpi values show two general trends of peat swamp evolution low gi and tpi values as indicator for drier swamp conditions like ombrogenous mires and high gi and tpi values which show a trend to water covered environments like topogenous mires in addition ash yields and gwi versus vi data also emphasize a general trend from topogenous to ombrogenous mires a decrease in water level towards the top of the seams and thus resulting in the development of domed mires is reflected by the newly introduced wci hence these parameters show recurrent peat swamp successions characterized by mineral and vitrinite rich coals typical for topogenous swamps and an evolution towards inertinite liptinite rich coals with low ash yield typical for ombrogenous swamps n alkane ratios like the carbon preference index cpi pristane n c17 phytane n c18 pristane phytane and the n c17 n c27 relationship indicate a strong correlation of these parameters with thermal maturity e g cpi values correlate with vitrinite reflectance sulphur organic carbon s toc ratios are quite uniform in clastic rocks with low to moderate toc contents but highly variable in coals probably reflecting variable sulphate availability during deposition of peats sphenophyll rich floral assemblages are restricted to low sulphur environments