modelling of the evolution of ground waters in a granite system at low temperature the stripa ground waters sweden abstract from chemical data collected by nordstrom and his colleagues on stripa ground waterswe have tried to model the evolution of the chemical composition of a ground water in a granitic system at low temperature the existence of two end member ground water compositions made it possible first to test the conventional model of a geothermal system according to which an overall equilibrium between the waters and a given mineral assemblage can be defined and then to show that such a model could be extended to low temperatures 10 c conversely if we know the mineral assemblage the equilibration temperature and the charge of the mobile ions in this case cl the composition of the solution is entirely fixed in our model of the stripa ground waters the existence of two end member ground water compositions can be explained by an evolution from a kaolinite albite laumontite equilibrium to a prehnite albite laumontite equilibium the latter requiring less al than the former we have also emphasized the importance of the cl ion concentrions ofof the ground waters because they cab be considered as indicators of the degree of reaction progress between rock and water thus determining the degree of equilibration of the system

the importance of colloids and mires for the transport of uranium isotopes through the kalix river watershed and baltic sea the importance of colloids and organic deposits for the transport of uranium isotopes from continental source regions and through the estuarine environment was investigated in the mire rich kalix river drainage basin in northern sweden and the baltic sea ultrafiltration techniques were used to separate uranium and other elements associated with colloids 10 kd and 3 kd from solute uranium and provided consistent results and high recovery rates for uranium as well as for other elements from large volume samples uranium concentrations in 0 45 m filtered kalix river water samples increased by a factor of 3 from near the headwaters in the caledonides to the river mouth while major cation concentrations were relatively constant 234 u 238 u ratios were high 234 u 770 1500 throughout the basin without showing any simple pattern and required a supply of 234 u rich water throughout the kalix river a large fraction 30 90 of the uranium is carried by 10 kd colloids which is compatible with uranium complexation with humic acids no isotopic differences were found between colloid associated and solute uranium within the baltic sea about half of the uranium is removed at low salinities the proportion that is lost is equivalent to that of river derived colloid bound uranium suggesting that while solute uranium behaves conservatively during estuarine mixing colloid bound uranium is lost due to rapid flocculation of colloidal material the association of uranium with colloids therefore may be an important parameter in determining uranium estuarine behavior mire peats in the kalix river highly concentrate uranium and are potentially a significant source of recoil 234 u to the mirewaters and river waters however mirewater data clearly demonstrate that only small 234 u 238 u shifts are generated relative to inflowing groundwater a simple box model of uranium accumulation in peat and transport through the mire that is compatible with the mire data demonstrates that with efficient removal of uranium from solution only small shifts in 234 u 238 u ratios can be generated in mirewater uranium the measurements and model calculations show that mirewaters are not the primary source of the uranium in the river bedrock groundwaters with high 234 u 238 u ratios and uranium concentrations must be the dominant source of riverine uranium

rock type control on erosion induced uplift eastern swiss alps abstract there is growing evidence that quaternary rock uplift in parts of the european alps is a consequence of climate and erosion driven isostatic rebound contemporary rates of rock uplift u in the swiss alps show two distinctive dome like peak regions that attain 1 6 mm yr 1 we focus on the alpenrhein catchment and its surroundings where one of these peak regions spatially coincides with widely exposed cretaceous bundner schist and lower tertiary flysch field assessments and analyses of hillslope gradient distributions quantitatively demonstrate the low rock mass strength and high erodibility of these rocks this is reflected in mean postglacial catchment erosion rates d 4 mm yr 1 as opposed to 0 7 mm yr 1 in more resistant crystalline rocks though largely inferred from landslide and debris flow prone tributary catchments 2 the localised erosion rates in bundner schist and flysch are among the highest documented for the alps and corroborated by historic suspended sediment yields and thus export from the region we further find that the steepness of bedrock rivers the density of large landslides and d correlate with the highest values of u our observations highlight the possibility that erosion of mechanically weak bundner schist and flysch enhanced by large landslides may have contributed to regional crustal unloading and concomitant rock uplift irrespective of whether this is betraying a coupling between long term uplift and erosion modulated by rock type our findings indicate that long term 10 3 to 10 4 yr geomorphic signals contained in bedrock river steepness spatial density of large landslides and postglacial erosion rates strikingly correlate with regional gradients of historic 10 1 yr rock uplift rates

long term behaviour of continental hydrothermal systems u series study of hydrothermal carbonates from the french massif central allier valley abstract u series dating of hydrothermal carbonates deposited by co2 rich thermo mineral waters of the french massif central provides new insights on the long term behaviour of a continental hydrothermal system dating of aragonite veins and travertines impregnating old terrace levels of the allier river allowed identification of the main episodes of surface deposition and thus factors likely to influence these circulations fifteen layers from three veins and four travertines from two separate areas were analysed sr isotope compositions were also measured on vein samples the results show that this region was subjected to at least 3 main episodes of surface or near surface hydrothermal deposition 253 to 208 ky 135 to 100 ky and less than 8 ky comparison of these ages with a global climatic curve indicates that preferential deposition of carbonates occurs during warm periods suggesting a strong influence of climatic conditions on the hydrothermal system it is suggested that this climatic influence does not necessarily imply the absence of carbonate deposition during cold and dry periods but rather that carbonate precipitation might occur at depth before the geothermal fluids reach the surface in addition the isotope compositions of fluids recorded by the 87sr 86sr and 234u 238u initial ratios in the aragonite veins from coudes remained remarkably constant over 250 ky ranging from 0 71360 to 0 71371 and from 3 10 to 3 39 respectively the two samples coming from saladis show a slightly higher 234u 238u initial ratio around 3 95 the constancy of these ratios over such a long period suggests a hydrothermal system in a near steady state with respect to water rock interaction we thus propose a possible model allowing a conservative steady state despite variations in the water recharge rates in response to the climatic variations the difference between 234u 238u initial ratios measured in the coudes and saladis systems suggests the existence of two separate reservoirs and constrains their lateral extension to a few km at most

slope distributions threshold hillslopes and steady state topography digital elevation models of two steady state mountain ranges the olympic mountains om and oregon coast range ocr are used to examine relationships between slope distributions the development of threshold hillslopes and steady state topography plots of drainage area versus slope for these mountain ranges exhibit substantial scatter that complicates comparison of range form to analytical theories and landscape evolution models contour plots of the density of such data reveal an attractor at the scale of the transition from hillslope processes to channel processes and log bin averaging reveals trends that parallel predictions of steady state erosion laws but with different rate laws for five distinct process domains hillslopes valley heads and colluvial bedrock and alluvial valley segments slope histograms computed for 100 km2 areas defined by a 10 10 km grid throughout the om exhibit approximately normal or exponential distributions in areas of active rock uplift and depositional topography respectively local slope distributions in the ocr also tend to be normally distributed but some are left skewed in areas with gentler slopes mean slopes determined both over the above referenced grid and a 10 km diam moving window are relatively invariant in the core of the om in spite of strong contrasts in bedrock erodibility and gradients in long term rock uplift rates in contrast the mean slopes in the ocr parallel latitudinal gradients in rock uplift rates and bedrock erodibility hence the slope distributions in the om and ocr reflect distinct relationships between development of threshold bedrock and soil mantled hillslopes and steady state topography

modes of formation of anomalously high radioactivity in oil field brines many oil field brines contain anomalously high radium concentrations a theoretical model proposed here suggests that such concentrations can be a function of the geochemical environments of petroleum reservoirs or can be caused by uranium occurrences associated with oil pools the model suggests that on a triangular diagram with barium radium 228 and radium 226 as the axes brines associated with uranium occurrences will plot relatively far toward the radium 226 corner radium rich brines associated with normal mineral assemblages will fall relatively close to the ba ra 228 side of the diagram geochemical differentiation of the radium source may provide a useful tool in exploration for uranium accumulations in petroliferous areas

an improved method for ra isotope 226ra 228ra 224ra measurements by gamma spectrometry in natural waters application to co2 rich thermal waters from the french massif central abstract an improved method was developed to measure 226 ra 228 ra and 224 ra in freshwaters by gamma spectrometry radium was selectively extracted from acidified samples using specific filters 3m empore radium rad disks the latter was subsequently analysed by gamma spectrometry simultaneous and direct determination of the activities of the three isotopes was performed by comparison of gamma rays of the radium rad disks with those of a calibrated standard disk this efficient and reliable method allowed a reduction of sample processing to a few hours this technique was applied to analyse the ra isotope compositions of several co 2 rich hydrothermal springs of the western border of the limagne graben french massif central the studied springs emerge from a succession of granitic outcrops lined up along a major fault their chemical compositions evolve from calcic and magnesian chloro bicarbonated to sodic bicarbonated all the springs display high ra activities probably linked to high co 2 content and or high cation content of these waters with various ra isotope ratios 226 ra activity ranges from 588 to 2287 mbq l and 228 ra activity from 260 to 1590 mbq l whereas 224 ra displays an activity between 245 and 1808 mbq l four of the six analysed springs have 228 ra 226 ra activity ratios lower than 0 7 thus significantly lower than the ratio expected from an interaction with a calc alkaline granitoid typically having 232 th 238 u activity ratio between 1 and 2 low 228 ra 226 ra ratio 0 27 of the northern water montpensier suggests the existence in this area of a zone of u concentration possibly resulting from u mobilization and accumulation induced by previous hydrothermal events the 224 ra 228 ra ratios display smaller variations they suggest short transit times from the zone of ra leaching to the surface a few days or a very shallow addition of 224 ra e g from a localised zone where 228 th could be preferentially adsorbed on the mineral surfaces in some cases these ratios might be used to infer differences in transit times of waters between neighboring springs

the geochemistry of ca sr ba and ra sulfates in some deep brines from the palo duro basin texas the geochemistry of ca sr ba and ra sulfates in some deep brines from the palo duro basin of north texas was studied to define geochemical controls on radionuclides such as 90sr and 226ra published solubility data for gypsum anhydrite celestite barite and raso4 were first reevaluated in most cases using the ion interaction approach of pitzer to determine solubility products of the sulfates as a function of temperature and pressure ionic strengths of the brines were from 2 9 to 4 8 m their temperatures and pressures up to 40 c and 130 bars saturation indices of the sulfates were computed with the ion interaction approach in one brine from the arkosic granite wash fades and four from the carbonate wolfcamp formation all five brines are saturated with respect to gypsum anhydrite and celestite and three of the five with respect to barite all are undersaturated by from 5 to 6 orders of magnitude with respect to pure raso4 226ra concentrations in the brines which ranged from 10 11 3 to 10 12 7 m are not controlled by raso4 solubility or adsorption but possibly by the solubility of trace ra solid solutions in sulfates including celestite and barite

flow and turbulence structure across the ripple dune transition an experiment under mobile bed conditions current knowledge of flow and turbulent processes acting across the sand bed continuum is still unable to unequivocally explain the mechanism s by which ripples become dunes understanding has been improved by comparative high resolution studies undertaken over fixed bedforms at different stages in the continuum however these studies both ignore the role of mobile sediment and do not examine flow structure during the actual transition from ripples to dunes the aims of the paper are i to describe flow and turbulence characteristics acting above mobile bedforms at several stages across the transition and ii to compare these data with those arising from experiments over fixed ripples and dunes laboratory experiments are presented that examine the turbulence structure across seven distinct stages of the transition from ripples to dunes single point acoustic doppler velocimeter sampling at three flow heights above a developing mobile boundary was undertaken time averaged statistics and the instantaneous quadrant record reveal distinct changes in flow structure either side of the change from ripples to dunes initially shear related high frequency vortex shedding dominates turbulence production this increases until two dimensional 2d dunes have formed thereafter turbulence intensities and reynolds stress decline and three dimensional dunes exhibit values found over 2d ripples this is the result of shear layer dampening which occurs when the topographically accelerated downstream velocity increases at a faster rate than flow depth activity at reattachment increases due to high velocity fluid imparting high mass and momentum transfer at the bed and or wake flapping suspended sediment may also play a role in turbulence dampening and bed erosion ejections dominate over sweeps in terms of event frequency but not magnitude strong relationships between inward interactions and sweeps and ejections and outward interactions suggest that mass and momentum exchanges are dependent upon activity in all four quadrants the results contradict the notion present in most physical models that larger bedforms exhibit most shear layer activity consequently an improved model for the ripple dune transition is proposed

evaluation of the groundwaters from the stripa mine using stable chlorine isotopes groundwater samples and a rock leachate sample from the stripa mine and south central sweden have been analysed for their 37cl values results reveal that the salinity found at depth in the groundwater is most likely derived form water rock interaction the overall distribution is one of 37cl enrichment with depth and with chloride concentration this trend is comparable to other sites in the fennoscandian shield where it is believed that deep groundwaters derive their 37cl values from the local bedrock

in situ neutron flux 36cl production and groundwater evolution in crystalline rocks at stripa sweden the meteoric input of36cl due to cosmogenic or nuclear weapon produced36cl cannot contribute significantly to the36cl present in the saline groundwaters up to 700 mg l 1 cl from the stripa granite the extent of in situ production of36cl has been estimated on the basis of the neutron fluxes within the granite and its surrounding leptite the36cl present in the groundwaters is attributed to either admixture of labelled cl from the leptite with cl from the granite or to the total derivation of groundwater chlorinity within the leptite followed by radiochemical ingrowth of36cl during subsequent groundwater residence within the granite the chloride derived from the leptite may be either matrix chloride or chloride from an external source which has had a long residence time within the leptite the implications of36cl in situ production for the estimation of groundwater residence times and for the geochemical evolution of groundwater chlorinity are discussed

natural radioelement solution by circulating groundwaters in the stripa granite natural radioelement concentrations in groundwaters from the fracture flow regime in the stripa granite were monitored during the period 1977 1986 uranium concentrations from depths of 80 m or less and in minewaters from above the hydraulic sink produced by the deepest mining level 410 m range from 10 to 90 ppb 234u238u activity ratios are characteristic of chemical leaching processes at the shallower depths whilst at about 350 m groundwaters occur which have an additional component of 234u by alpha recoil processes at greater depths u concentrations are indicative of the changed redox conditions and are subject to activity ratio enhancement by the alpha recoil process groundwater residence times may be estimated from the rate of such recoil solution of 234u in zones where chemical leaching of u is not active the 222rn contents of the minewaters are extremely high and can be related to the 222rn flux from fracture surfaces and the fracture width the fracture apertures range from 10 mm for the shallow groundwater zone 222rn contents m for water from the deepest borehole section 222rn content 100 kbq kg 1 the activity ratios 234th238u 210pb222rn and 210po222rn have been used to estimate residence times for th pb and po isotopes solution of ra is controlled by chemical rather than alpha recoil processes the 226ra content of the groundwater increases with salinity and is well correlated with groundwater ca content the 228ra226ra activity ratios in the groundwaters suggest that water rock interaction occurs predominantly with the average granitic matrix rather than with highly uraniferous fracture mineralisation the behaviour of ra th and po isotopes may be used to assess that of homologous fission product and actinide constituents of nuclear wastes in groundwaters

radium isotopes to trace uranium redox anomalies in anoxic groundwater abstract 223ra 224ra 226ra and 228ra isotopes have been measured in groundwaters from depths ranging 50 900 m in fractured crystalline bedrock forsmark sweden to understand the reason for elevated up to 150 g l aqueous uranium uaq at 400 650 m depth ra isotope data is interpreted alongside previously reported 222rn 234u and 238u data as well as phreeqc geochemical modelling and uranium mineralogy a novel 223ra 226ra gw based approach where brackets and gw subscript refer to expression of an activity ratio measured from groundwater to groundwater residence time estimation shows that elevated uaq is most common in holocene age groundwaters of marine origin although these groundwaters are geochemically reducing the 223ra 228ra corr where corr subscript refers to a correction applied to compare 223ra 228ra gw to the more commonly reported 226ra 228ra gw suggest that they interact with u rich pegmatites containing proterozoic and palaeozoic age ca u vi silicate minerals which are undersaturated in the present groundwaters local aqueous u vi can be stabilized in ca2uo2co30 complexes at pe values as low as 4 5 but is susceptible to reduction after a modest decrease in pe value alkalinity or ca concentration the 223ra 228ra corr and 224ra 228ra gw also suggest that u vi aq precipitates as uo2 x at the interface between marine and non marine groundwaters from these data local uaq is proposed to be governed by on going water rock interaction involving old u vi minerals

the behavior of u and th series nuclides in groundwater groundwater has long been an active area of research driven by its importance both as a societal resource and as a component in the global hydrological cycle key issues in groundwater research include inferring rates of transport of chemical constituents determining the ages of groundwater and tracing water masses using chemical fingerprints while information on the trace elements pertinent to these topics can be obtained from aquifer tests using experimentally introduced tracers and from laboratory experiments on aquifer materials these studies are necessarily limited in time and space regional studies of aquifers can focus on greater scales and time periods but must contend with greater complexities and variations in this regard the isotopic systematics of the naturally occurring radionuclides in the u and th decay series have been invaluable in investigating aquifer behavior of u th and ra these nuclides are present in all groundwaters and are each represented by several isotopes with very different half lives so that processes occurring over a range of time scales can be studied table 1 within the host aquifer minerals the radionuclides in each decay series are generally expected to be in secular equilibrium and so have equal activities see bourdon et al 2003 in contrast these nuclides exhibit strong relative fractionations within the surrounding groundwaters that reflect contrasting behavior during release into the water and during interaction with the surrounding host aquifer rocks radionuclide data can be used within the framework of models of the processes involved to obtain quantitative assessments of radionuclide release from aquifer rocks and groundwater migration rates the isotopic variations that are generated also have the potential for providing fingerprints for groundwaters from specific aquifer environments and have even been explored as a means for calculating groundwater ages view this table table 1 radionuclides important in groundwater studies the highly fractionated nature of the

saline groundwater and brines in crystalline rocks the contributions of john andrews and jean charles fontes to the solution of a hydrogeological and geochemical problem abstract investigations into the suitability of crystalline rock for the long term containment of high level nuclear waste were initiated in the early 1970s a significant task was thereby to assess fluid movements to and from potential repositories this paper focuses on the contributions of j n andrews and j ch fontes to this problem and presents some aspects of their work on fluids in crystalline rock environments waste repository studies saw major progress with the initiation of the stripa project in 1977 andrews joined this project during the first year and participated until its closure in the late 1980s fontes involvement began during the second phase of the project after the first ideas about the geochemistry and evolution of groundwater encountered in the stripa granite had been developed the problems associated with dating of such hydrogeological systems their geochemical evolution and the question of origin of dissolved salts occupied both of them and their co workers those privileged to participate in the long and lively discussions will remember these times as extremely fruitful the results are documented in a multitude of international studies where the stripa ideas were further developed and tested not only in sweden based on the data from swedish and other environments with crystalline rock brines andrews fontes and others had recognised the need to develop at least one additional project designed to clarify major points of uncertainty regarding the age and evolution as well as the origin of saline fluids found in most crystalline rock environments the untimely death of these two applied geochemists is the reason why these discussions have not yet been concluded

development of glacial valley cross sections under conditions of spatially variable resistance to erosion abstract a simulation model that examines the development of valley cross profiles as a result of glacial erosion has been constructed by placing a finite element model for ice flow within an iterative program that modifies channel cross section form on the basis of an erosion equation the simulation model has previously been used to examine how different flow laws erosion laws and ice discharge histories affect medium scale landform development this allows us to better understand the development of glacial landforms and also provides a critical test for erosion and flow laws within the erosion component of the simulation program it is possible to specify spatial variations in bedrock erodibility in order to examine the effect of spatially variable lithologies on form development as an initial test of form development under these conditions a central area of enhanced erodibility is placed in the valley center in this case active glacial channels develop that are narrower and deeper than those which occur with homogenous bedrock this change in form occurs as long as the weaker zone is small enough that the active channel does not eventually narrow to a stage such that it is entirely contained within the weaker material and as long as it is large enough that it continues to have a significant impact on overall discharge through the section form variation occurs because the weaker central zone enhances the lateral gradient of the erosion rate which is critical for form development a central area of more erodible bedrock changes not only the form of the active glacial channel but also the convexity of side slopes that are left above the glacier as it erodes downwards into the landscape the absence of a classic u shaped cross section should not be taken a priori to suggest either absence of glacial erosion or ineffective glacial erosion rather the combination of active glacial and hillslope processes in a landscape with spatially and temporally variable ice discharge and rock characteristics can create a diverse set of cross section forms

large scale intrusion of shallow water into a vertical fracture zone in crystalline bedrock initial hydrochemical perturbation during tunnel construction at the aspo hard rock laboratory southeastern sweden on march 13 1991 construction of the entrance tunnel to the aspo hard rock laboratory opened a vertical fracture zone at a depth of 70 m this provides an opportunity to study geochemical changes resulting from shallow water inflow into a crystalline bedrock aquifer as anticipated during construction and operation of a deep repository for spent nuclear fuel chloride ion is a natural conservative tracer for mixing between the dilute cl 10 mg l 1 shallow groundwater and the saline cl 5000 mg l 1 native groundwater of the fracture zone a sharp dilution front corresponding to 80 dilution of the native groundwater indicated arrival of shallow groundwater in the entrance tunnel after 3 weeks in spite of this large input of shallow water the fracture zone remains predominantly anoxic major element hydrochemistry and carbon and oxygen stable isotope data indicate large inputs of alkalinity and biogenic co2 g input of organic carbon with shallow groundwater provides a possible energy and carbon source for anaerobic respiration there is no evidence for sulfate reduction and fe iii oxyhydroxide fracture minerals are the only other dominant electron acceptor observed

interplay between erosion and tectonics in the western alps bedrock fission track analysis high resolution petrography and heavy mineral analyses of sediments are used to investigate the relationships between erosion and tectonics in the western alps along the aosta valley cross section exhumation rates based on fission track data are higher in the fault bounded western block than in the eastern block 0 4 1 5 vs 0 1 0 3 mm yr 1 erosion rates based on the analysis of bed load in the dora baltea drainage display the same pattern and have similar magnitudes in the relative sub basins 0 4 0 7 vs 0 04 0 08 mm yr 1 results highlight that climate relief and lithology are not the controlling factors of erosion in the western alps the main driving force behind erosion is instead tectonics that causes the differential upward motion of crustal blocks

evaluation of groundwater quality based on radiological and hydrochemical data from two uraniferous regions of western iberia nisa portugal and ciudad rodrigo spain the regions of nisa portugal and ciudad rodrigo spain are characterized by a high radiation background due to the presence of uranium enriched rocks to evaluate the water quality of the shallow aquifers and the relationship between radiological and non radiological variables a set of 41 samples was collected mainly from springs and analyzed for the radioisotopes 238u 234u 226ra and 222rn as well as for some major and minor cations the results obtained for the cationic composition in both areas show some differences in terms of geological bedrock with higher mineralization and hardness in the spanish samples ca mg facies the nisa samples are included in the na k facies the indicative effective dose was calculated for several age groups on average the effective dose is higher in nisa due to the activity in 226ra and 25 of the total dataset puts 222rn above the recommended acceptable maximum despite the low scale ancient uranium exploitation works in the nisa area in comparison to those carried out on the spanish side the higher risk calculated in the portuguese region reinforces the importance of taking into account the natural background when the goal is to control the exposure of the population to ionizing radiation

deuterium oxygen 18 and tritium in stripa groundwater deuterium oxygen 18 and tritium determinations show that groundwaters in the fractures of the stripa granite are of meteoric origin not affected by secondary isotope effects evaporation or isotope exchange deep ground waters have lower 18o and 2h contents than recent shallow groundwaters the differences are most likely due to recharge during cooler climatic conditions however no age information can be derived because recharge could have occurred before the last major climatic improvement following the last deglaciation during minor climatic variations during the more recent past or could be the result of regional groundwater flow low 18o contents are paralleled by increasing salinities with highest salinities limited to a narrow fracture zone at a depth of about 800 m below ground surface most saline waters sampled appear to represent mixtures of a saline component with an isotopically depleted water and local fresh water the presence of young groundwaters is indicated by bomb produced 3h all surface boreholes contain tritium indicating residence times 35 years however tritium is also found in some boreholes drilled at the 300 m mine levels and its presence may be due to flows induced in response to heater tests low but detectable 3h contents about 0 1 to 1 tu in v2 at about 850 m below groundsurface are discussed either as subsurface production and or as a result of admixtures of small amounts of recent water to old groundwater

radioisotope dynamics the origin and fate of nuclides in groundwater the use of radionuclides as clocks for groundwater dating and as probes to investigate the geometry and spatial extent of the contact area between rocks and water is reviewed subsurface production rates for 222 rn 37 ar 55 kr 39 ar 36 cl 3 he 4 he and 40 ar in various rock types are listed measured rn fluxes from the surface of sandstone grains and from pieces of granite point to scale dependent diffusion coefficients the temporal evolution of subsurface produced 222 rn 37 ar 85 kr and 39 ar activities in groundwaters yields radionuclide escape factors between 0 1 and 9 for the stripa granite sweden and between 1 and 4 for the milk river sandstone canada the combination of 3 h 85 kr 39 ar 14 c 36 cl 4 he in the uk triassic sandstone aquifer allows groundwater dating up to 40 000 a very old groundwaters can be studied using cl 36 cl and 4 he evolution as demonstrated in the milk river aquifer in canada

on the causes and modes of exhumation and lateral growth of the alps 1 a compilation of the apatite and zircon fission track ages of the alpine chain points to markedly different patterns of cooling and exhumation of the eastern alps compared to the central and western alps the site of exhumation and shortening in the western alps migrated outward whereas it was more stationary in the eastern alps where it created a narrower metamorphic belt a correlation of these observations to the deep structure of the orogen suggests that north directed lower crustal wedging induces northward propagation of the deformation and exhumation front in the middle and upper crust of the central and western alps the absence of such lower crustal wedges in the eastern alps does not induce a similar shift of deformation but rather a long term localization of shortening and exhumation in one and the same area namely the axial zone of the orogen a critical review of the temporal correlations between inferred changes in the erosional efficiency of the alps and tectonic phases points to a negative correlation and hence no erosional control on the shifts of the deformation front of the alps therefore we conclude that changes in the deep structure and rheology of the orogen instead of changes in its erosional efficiency exerted the prime control on the lateral growth of the alps

radioelements radiogenic helium and age relationships for groundwaters from the granites at stripa sweden abstract the solution of radioelements and radiogenic 4he by groundwaters in fractured rocks is dependent upon the radioelement distribution in the rock matrix and the extent of the rock water interface the 234 u 238 u activity ratio and the dissolved u rn and he contents of such groundwaters respond to changes in the flow regime with time although 234 u 238 u activity ratios change with groundwater residence time as a consequence of 234th recoil induced solution of 234u the activity ratio is strongly influenced by the u distribution within fractures by the extent of the rock water interface and by the amount of 238u in solution a model for the quantitative evaluation of these effects is presented groundwaters from depths up to 880 m in the stripa granite have variable dissolved uranium contents and 234 u 238 u activity ratios the uranium geochemistry is primarily determined by variations in flow path rather than by groundwater age dissolved radiogenic 4he in the groundwaters increases with their depth of origin and is dependent upon the u content of the granite and upon its fracture porosity it increases with groundwater residence time but movement of 4he by diffusion and transport processes make the actual groundwater age indeterminate

effects of large deep seated landslides on hillslope morphology western southern alps new zealand 1 morphometric analysis and air photo interpretation highlight geomorphic imprints of large landslides i e affecting 1 km2 on hillslopes in the western southern alps wsa new zealand large landslides attain kilometer scale runout affect 50 of total basin relief and in 70 are slope clearing and thus relief limiting landslide terrain shows lower mean local relief relief variability slope angles steepness and concavity than surrounding terrain measuring mean slope angle smoothes out local landslide morphology masking any relationship between large landslides and possible threshold hillslopes large failures also occurred on low gradient slopes indicating persistent low frequency high magnitude hillslope adjustment independent of fluvial bedrock incision at the basin and hillslope scale slope area plots partly constrain the effects of landslides on geomorphic process regimes landslide imprints gradually blend with relief characteristics at orogen scale 102 km while being sensitive to length scales of slope failure topography sampling and digital elevation model resolution this limits means of automated detection and underlines the importance of local morphologic contrasts for detecting large landslides in the wsa landslide controls on low order drainage include divide lowering and shifting formation of headwater basins and hanging valleys and stream piracy volumes typically mobilized yet still stored in numerous deposits despite high denudation rates are 107 m3 and theoretically equal to 102 years of basin wide debris production from historic shallow landslides lack of absolute ages precludes further estimates deposit size and mature forest cover indicate residence times of 101 104 years on these timescales large landslides require further attention in landscape evolution models of tectonically active orogens

giant non catastrophic landslides and the long term exhumation of the european alps landslides influence local slope morphology affect sediment flux from hillslopes to rivers and mass wasting in response to tectonics and climate forcing however the links between giant non catastrophic landslides known as deep seated gravitational slope deformations dsgsds and the long term evolution of orogenic landscapes are almost unknown we explore these links in the european alps using the first orogen scale inventory of dsgsds 900 over an area 105 km2 and a dataset of published apatite fission track ages 1000 that provides an estimate of the long term exhumation patterns of the orogen we show that dsgsds are more widespread than previously considered and exhibit an orogen scale distribution not explained by well known local lithological and structural controls we test the hypothesis that this orogen scale distribution correlates to the long term evolution of the alps by subdividing the study area into 37 square sub areas 50 50 km classified according to combinations of long term exhumation and mean annual rainfall on each sub area we perform a morphometric analysis of topography hypsometry relief slope excluding local and regional controls due to rock type and structure dsgsds tend to cluster in areas with intermediate exhumation rates fission track age between 10 and 40 ma where large scale topography is less dissected and incision is localised along major valleys here dsgsd abundance correlates positively with the degree of valley incision and related relief instead dsgsds lack in areas which underwent either low exhumation rates resulting in insufficient relief production or high exhumation rates associated to rapid uplift or higher erosional dissection of topography negative correlation between dsgsd abundance and mean annual rainfall suggests that effective hydrological surface processes contribute on the long term timescale to the development of large scale topography unfavourable to dsgsds especially in areas of high exhumation rates where dsgsds are abundant long lasting slope deformations effectively adjust post glacial relief by reducing slope inclination values and are thus expected to significantly contribute to the long term denudation of active orogens

radium geochemistry of ground waters in paleozoic carbonate aquifers midcontinent usa the purpose of this study was to elucidate the processes controlling the distribution and behavior of the longerlived ra isotopes in continuous paleozoic carbonate aquifers of parts of missouri kansas and oklahoma activities of 228 ra and 226 ra were analyzed in fresh and saline ground waters brines and rocks the fluids have a wide salinity range 200 250 000 mg l 1 total dissolved solids the 226 ra activity ranges from 0 66 7660 dpm kg 1 and correlates with salinity and other alkaline earth element ca sr and ba concentrations the range of 228 ra 226 ra ratios in the fluids 0 06 1 48 is similar to that in the aquifer rocks 0 21 1 53 the relatively low mean fluid 228 ra 226 ra ratio 0 30 reflects the low th u ratio of the predominant carbonate aquifer rock radium occurs mostly r77 as ra 2 species in the fluids salinity dependent sorption desorption processes with log k values from 10 0 10 4 and negatively correlated with salinity involving th enriched surface coatings on aquifer flow channels can explain the rapid solid fluid transfer of ra isotopes in the system and the correlation of ra with

tectonic control on the late stage exhumation of the aar massif switzerland constraints from apatite fission track and u th he data 1 we examine the hypothesis that pliocene exhumation of the external massifs in the central alps is controlled by climatic change new thermochronological data from the western gastern aar massif are used to investigate the timing extent and reasons for neogene exhumation our data reveal that exhumation was constant with 0 5 km ma over the last 10 ma in the north in the southern part exhumation was of the same order until 3 5 ma but then increased gradually toward the south to values of up to 1 2 km ma resulting in overall northward tilting of the western aar massif we explain this accelerated exhumation in the south after 3 5 ma mainly by tectonic denudation in the footwall of the rhone simplon fault and discuss changes in deep crustal configuration which may have triggered south directed normal faulting we propose that the rhone river was structurally trapped by the rhone simplon normal fault zone which additionally enhanced erosion in the southern section of the aar massif climatic forcing may have an impact in the very late stage of exhumation due to alpine glaciation in the late pliocene

in situ radionuclide transport and preferential groundwater flows at ineel idaho decay series disequilibrium studies uranium and thorium decay series disequilibria in groundwater occur as a result of water rock interactions and they provide site specific natural analog information for assessment of in situ long term migration of radionuclides in the far field of a nuclear waste disposal site in this study a mass balance model was used to relate the decay series radionuclide distributions among solution sorbed and solid phases in an aquifer system to processes of water transport sorption desorption dissolution precipitation radioactive ingrowth decay and recoil isotopes of u 238u 234u th 232th 230th 228th 234th ra 226ra 228ra 224ra and rn 222rn were measured in 23 groundwater samples collected from a basaltic aquifer at the idaho national engineering and environmental laboratory ineel idaho the results show that groundwater activities of th and ra isotopes are 2 4 orders lower than those of their u progenitors which average 1 35 0 40 dpm 238u l with 234u 238u ratios of 1 6 3 0 222rn activities range from 20 to 500 dpm l modeling of the observed disequilibria places the following constraints on the time scale of radionuclide migration and water rock interaction at ineel 1 time for sorption is minutes for ra and th time for desorption is days for ra and years for th and time for precipitation is days for th years for ra and centuries for u 2 retardation factors due to sorption average 106 for 232th 104 for 226ra and 103 for 238u 3 dissolution rates of rocks are 70 to 800 mg l y 4 ages of groundwater range from 10 to 100 years contours of groundwater age as well as spatial patterns of radionuclide disequilibria delineate two north south preferential flow pathways and two stagnated locales relatively high rates of dissolution and precipitation and recoil of 222rn occur near the groundwater recharging sites as well as in the major flow pathways decay of the sorbed parent radionuclides e g 226ra and 228ra on micro fracture surfaces constitutes an important source of their daughter 222rn and 228th activities in groundwater

the transport of u and th series nuclides in sandy confined aquifers a comprehensive evaluation of the transport of u th ra and rn nuclides of the 238 u and 232 th decay series in an unconfined sandy aquifer long island ny was conducted groundwater data are compared with results of a theoretical transport model of weathering of aquifer grains and interaction with surface coatings to establish relationships between the concentrations of the radionuclide activities in the water and flow line distance the data provide estimates for geochemical parameters including weathering rates and chemical reactivities in both the vadose zone and the aquifer a theoretical treatment of the transport is presented that considers the reaction between the water and a reactive surface layer it is found that a model with chemical exchange between the surface layer and the water for all species is not valid and that the effects of saturation and irreversible precipitation of th is required the water table shows a relatively wide range in u activities the only element in the u th series for which vadose zone input is significant in the aquifer high weathering of u and recoil inputs of 234 u to the water occur in the upper 3 m of the vadose zone while lower weathering and removal of u from the water occur below the deeper aquifer has variable 238 u activities that can be accounted for by input from the vadose zone and is not a result of non conservative behavior the isotopic composition of u is shown to be directly related to the recoil rate relative to the weathering rate the wide range of 238 u in the aquifer waters is a reflection of diverse vadose zone inputs showing that dispersive mixing is not a dominant effect the higher values of 234 u in the aquifer reflect the recoil weathering input ratios from within the aquifer where the weathering rate is lower than the vadose zone both high u activities and high 234 u values cannot be obtained in the vadose zone or within reasonable flow distances in the aquifer radium isotopes are found to be in exchange equilibrium with the surface layer 224 ra 228 ra and 226 ra have comparable activities throughout the aquifer in the vadose zone the dominant input of ra to groundwater is weathering and recoil as found elsewhere the 222 rn in the water is a large fraction 5 of the rn produced in the aquifer rock this cannot be due to ra precipitation onto surface coatings in the aquifer as supported by present weathering with th in exchange equilibrium with the surface layer it is found that th is saturated in the waters under oxidizing conditions so that the weathering input is irreversibly precipitating onto surfaces however it is shown that under somewhat reducing conditions th activities are much higher and the th u ratio in the solution is approximately that of the rock we propose that under oxidizing conditions the source of rn is a surface coating enriched in 232 th and 230 th this th was precipitated in an earlier phase during rapid dissolution of readily weathered phases that contain 10 of the u th inventory of the rock with the associated u carried away in solution therefore the previously precipitated 230 th and 232 th produce daughter nuclides in the surface coating which are the dominant contributors of ra and rn to the ground water in particular rn is provided by very efficient losses by diffusion or recoil from the surface coating this then does not require recent large recoil losses from the parent rock or the presence of nanopores in the rock the first data of both long lived 232 th and short lived 234 th and 228 th in ground water is reported the th isotope activities indicate that desorption kinetics are slow and provide the first estimate based on field data of the th desorption rate from an aquifer surface the mean residence time of th in the surface coating is 3000 y while in the water it is 1 h ra is in partition equilibrium with the aquifer surface layer however the strong fixation of th on surface coatings is very susceptible to changes in oxidation state as is shown by a comparison of two adjacent aquifers this makes it difficult to define with certainty the retentive characteristics in natural systems in general it is shown that the distributions of naturally occurring nuclides can be used to calculate values for transport parameters that are applicable to the transport of anthropogenic nuclides

the u contents and 234u 238u activity ratios of dissolved uranium in groundwaters from some triassic sandstones in england abstract the isotopic compositions of dissolved uranium in groundwaters of age up to 36 000 a from the east midlands triassic sandstone and in saline fluids from deep geothermal boreholes in the wessex basin have been investigated groundwaters from the east midlands have u contents which lie on a normal distribution and average 0 75 g kg 1 with a standard deviation of 0 4 g kg 1 the 234 u 238 u activity ratios for the dissolved u in these groundwaters have minimum values between 3 and 4 some groundwaters have further enhancement of the 234 u 238 u activity ratio up to 7 but this is not related to groundwater age it is shown that uranium solution is primarily controlled by carbonate solution involving the cement phase of the sandstone and that the 234 u 238 u activity ratios are the results of preferential chemical etch of 234 u relative to 238 u an eh ph stability field diagram calculated for the average groundwater hco 3 contents in the aquifer shows that the uranyl carbonate complexes uo 2 co 3 2 2 and uo 2 co 3 3 4 stabilise uranium solution in the east midlands groundwaters in the wessex basin the redox conditions indicate that uranium deposition should occur and this is reflected in the very low u content of the geothermal fluids g kg 1 the residence time of these thermal waters probably exceeds 15 ma and a steady state 234 u 238 u activity ratio due to alpha recoil induced solution of 234 u should therefore have been attained the activity ratio 2 0 is very much less than the theoretical steady state ratio 10 20 for recoil processes in the interstitial fluids of the sandstone it is concluded that u in the interstitial surfaces must have been sealed against alpha recoil processes by a phase of low u content if the thermal water has evolved from groundwater similar to that in the east midlands triassic sandstone decay of excess 234 u must have occurred the time required for this decay is at least 0 25 ma if no alpha recoil solution of 234 u occurs and is 1 25 ma if an alpha recoil steady state has been attained the general implications of the study on the use of 234 u 238 u activity ratio changes for the estimation of groundwater residence times are discussed

meso cenozoic basin and carbonate platform development in the sw dolomites unraveled by basin modelling and apatite ft analysis rosengarten and latemar northern italy abstract the rosengarten and latemar middle triassic carbonate platforms indicate similar subsidence patterns during equivalent times of platform evolution as calculated by numerical basin reverse modelling in the case of rosengarten and latemar thermo tectonic subsidence is the most significant among all three subsidence components thermo tectonic s flexural s compaction induced s hence the influence of differential tectonics as recorded in the formation of structural highs and lows in the dolomites during the lower to middle anisian almost ceases in late anisian times basin modelling of rosengarten and latemar requires the correlation and integration of two sets of chronostratigraphic data from buchenstein fm basin and schlern dolomite fm 1 platform subsidence modelling argues for a microcycle i e a single shallowing upward cycle duration of less than 1 97 ka in the cyclic succession at latemar however previous time series analyses identify milankovitch cyclicities in larger order cycle stacking patterns and thus indicate a microcycle duration of 4 2 ka according to each model total subsidence reaches values of 650 700 m ma 4 2 ka model or 780 850 m ma 1 97 ka model during the first stage of platform evolution as both platforms successfully keep up with this subsidence peak it is evident that the carbonate factory despite its low diversity must have recovered from the p t faunal crisis after this regionally observed peak subsidence drops and triggers fast progradation at rosengarten subsidence in the study area is controlled by active strike slip tectonics and the subsequent formation of a magmatic chamber predazzo monzoni above the deep reaching truden stava line the area close to this tectonic line and to the volcanic centre of predazzo monzoni undergoes a higher heat flow pulse during the late ladinian and is possibly buried at shallower levels than the rosengarten area as shown by fission tracks in apatites the heat flow pulse almost disappears laterally underlining the localised thermal influence of the late ladinian volcano thermal event of predazzo monzoni

cosmogenic 10be derived denudation rates of the eastern and southern european alps denudation rates from cosmogenic 10be measured in quartz from recent river sediment have previously been used in the central alps to argue that rock uplift occurs through isostatic response to erosion in the absence of ongoing convergence we present new basin averaged denudation rates from large rivers in the eastern and southern european alps together with a detailed topographic analysis in order to infer the forces driving erosion denudation rates in the eastern and southern alps of 170 1 400 mm ky 1 are within a similar range to those in the central alps for similar lithologies however these denudation rates vary considerably with lithology and their variability generally increases with steeper landscapes where correlations with topographic metrics also become poorer tertiary igneous rocks are associated with steep hillslopes and channels and low denudation rates whereas pre alpine gneisses usually exhibit steep hillslopes and higher denudation rates molasse flysch and schists display lower mean basin slopes and channel gradients and despite their high erodibility low erosion rates exceptionally low denudation rates are also measured in permian rhyolite which has high mean basin slopes we invoke geomorphic inheritance as a major factor controlling erosion such that large erosive glaciers in the late quaternary cold periods were more effective in priming landscapes in the central alps for erosion than in the interior eastern alps however the difference in tectonic evolution of the eastern and central alps potentially adds to differences in their geomorphic response their deep structures differ significantly and unlike the central alps the eastern alps are affected by ongoing tectonic influx due to the slow motion and rotation of adria the result is a complex pattern of high mountain erosion in the eastern alps which has evolved from one confined to the narrow belt of the tauern window in late tertiary time to one affecting the entire underthrust basement orogenic lid and parts of the southern alps today

giant landslides topography and erosion abstract distributions of slope angles in tectonically active mountain belts point to the development of threshold conditions where hillslopes attain a critical inclination or height at which they fail readily because of limitations in material strength it has been proposed that hillslopes adjust to rapid uplift and bedrock incision through an increase in the rate of relief limiting landsliding rather than gradual slope steepening here we test this concept by investigating the relationship between mean local relief h which we take to be a proxy of long term erosion rates e and the occurrence of over 300 of the largest v 10 8 m 3 terrestrial landslides on earth we find that nearly two thirds of these giant landslides have occurred in the steepest 5 of the earth s land surface where relief is close to its proposed upper strength limit they are primarily located in deeply incised valleys along fault bounded fringes of active mountain belts and in volcanic arcs this distribution coincides with areas of high long term erosion rates 4 mm yr 1 confirming that giant landslides contribute to rapid denudation of mountains most of the eroded volume is concentrated in the smallest but steepest parts of mountain belts and volcanic arcs first order estimates of minimum erosion rates accomplished by the largest landslides are 0 01 mm yr 1 these rates are between 1 and 10 of the late pleistocene to holocene mean erosion rates in a given area importantly the landslide erosion rates show a nonlinear increase with mean local relief suggesting that the contribution of giant landslides in total and per event increases significantly with increasing overall erosion rates however giant landslides also occur in areas of lower than average relief h 300 700 m irrespective of whether threshold hillslopes have developed or not factors contributing to these failures include soft rocks extensive low angle discontinuities high rates of fluvial bedrock incision and tectonically driven deformation and slope loading

radioelement u th rn concentrations in norwegian bedrock groundwaters twenty eight samples of groundwater from bedrock boreholes in three distinct norwegian geological provinces have been taken and analyzed for content of rn u and th together with a wide variety of minor and major species median values of 290 bq 1 7 6 g 1 and 0 02 g 1 were obtained for rn u and th respectively while maximum values were 8500 bq 1 170 g 1 and 2 2 g 1 commonly suggested drinking water limits range from 8 to 1000 bq 1 for radon and 14 to 160 g 1 for uranium radioelement content was closely related to lithology the lowest concentrations being derived from the largely caledonian rocks of the trondelag area and the highest from the precambrian iddefjord granite of southeast norway 11 boreholes where median values of 2500 bq 1 15 g 1 and 0 38 g 1 respectively were obtained the iddefjord granite is not believed to be unique in norway in yielding high dissolved radionuclide contents in groundwaters and several other granitic aquifers warrant further investigation in this respect

the behaviour of short lived radiogenic lead isotopes 214pb and212pb in groundwaters and laboratory leaching experiments abstract the concentrations of 214 pb half life 26 4minutes and 22 rn half life 3 84days have been measured in deep groundwaters of gujarat india the results show that the abundance of 214 pb in the water is only 25 of that expected from its production through the radioactive decay of dissolved 222 rn this deficiency if modelled in terms of a first order removal yields a residence time of 10 minutes for 214 pb in these waters the estimated residence time for 214 pb is the shortest observed for any nuclide in natural water systems and suggests that reactive nuclides lead like could be removed from aqueous phases to adjoining solid surfaces on extremely short time scales results of laboratory experiments using the 212 pb 224 ra pair are compatible with the observed fast removal of 214 pb from groundwaters re evaluation of 234 th residence times in these waters using a model with a recoil flux of 234 th into aqueous phase the same as that of 222 rn yields values in the range of 23 to minutes very similar to that of 214 pb this concordancy in the residence times seems to suggest that the geochemical behaviour of 234 th and 214 pb in these waters is quite similar

222rn solution by the circulating fluids in a hot dry rock geothermal reservoir abstract the mechanism of 222 rn release into fracture fluids by direct alpha recoil lattice and grain boundary micro crack diffusion is discussed experimental measurements of 222 rn release into surrounding air and water phases have been made for crystalline rock specimens with well defined surface areas the 222 rn flux from an infinite plane surface and hence the effective diffusion length of 222 rn in the rock matrix has been estimated the 222 rn flux from plane crystalline rock surfaces has been used in conjunction with a simple hydrological model of the reservoir to calculate the 222 rn content of the return fluids of a geothermal doublet circulation system for given production rate and piezometric difference between the injection and production wells the 222 rn content of the return fluid is dependent upon the distribution of flow path lengths and fracture apertures in the reservoir matching of the calculated and experimental 222 rn contents of the return fluids has been used to select appropriate parameters for the reservoir model and hence to estimate the extent of the heat transfer surface the model estimates the fracture width of the flow paths total swept surface area and fracture volume within the reservoir

miocene to present differential exhumation in the western alps insights from fission track thermochronology 1 analysis of cooling age patterns yielded by low temperature thermochronometers provides key information about the role played by tectonic discontinuities during the late stages of exhumation of metamorphic belts in the western alps fission track data published so far are heterogeneously scattered and concentrated in few structural domains preventing analyses at the scale of the whole belt the new apatite fission track data reported in this work obtained with the external detector method as well as the population method in very low u content samples fill this gap they constrain the postmetamorphic evolution of the western alps along two transects from the foreland to the retroforeland unraveling the effective role played by some major faults during the exhumation of the belt at shallow crustal levels a clear regional pattern characterized by decreasing ages moving from the axial sector to the european external sector of the belt and by an along strike gradient with increasing ages from north to south has been unraveled evident breaks in this age pattern have been detected in correspondence of faults that are near parallel to the trend of the belt pointing to the occurrence of active tectonics during and after exhumation the most apparent breaks have been observed in the axial sector of the belt where the postmetamorphic deformation would have been negligible according to classic tectonic models faults located in the axial sector split the belt into two major blocks eastern and western since the miocene the western block experienced higher exhumation rates than the eastern one such differential exhumation was accommodated in the northern portion of the belt thanks to reverse motion along the internal houiller fault which occurred in a convergent transcurrent framework to the south it was accommodated instead by normal reactivation of the brianconnais front and by activity of the longitudinal fault system which occurred in a divergent transcurrent framework the tectonic activity affecting the axial sector of the belt in a context of regional dextral strike slip is coeval with the forward propagation of the external thrusts and of similar magnitude we suggest that the contrasting kinematic regimes i e convergent versus divergent transcurrence observed in the western alps moving along strike were responsible of the increasing exhumation rates toward the north revealed in both blocks by the along strike age gradient the higher exhumation rates recognized northward would be related to an increasing importance of crustal shortening that promoted erosion during the late stages of exhumation of the belt

tectonic vs gravitational morphostructures in the central eastern alps italy constraints on the recent evolution of the mountain range abstract deep seated gravitational slope deformations dsgsds influence landscape development in tectonically active mountain ranges nevertheless the relationships among tectonics dsgsds and topography are poorly known in this paper the distribution of dsgsds and their relationships with tectonic structures and active processes surface processes and topography were investigated at different scales over 100 dsgsds were mapped in a 5000 km2 sector of the central eastern alps between the valtellina engadine and venosta valleys detailed lineament mapping was carried out by photo interpretation in a smaller area about 750 km2 including the upper valtellina and val venosta fault populations were also analysed in the field and their mechanisms unravelled allowing to identify different structural stages the youngest being consistent with the regional pattern of the ongoing crustal deformation finally four dsgsd examples have been investigated in detail by geological and 2d geomechanical modelling dsgsds affect more than 10 of the study area and mainly cluster in areas where anisotropic fractured rock mass and high local relief occur their onset and development is subjected to a strong passive control by mesoscopic and major tectonic features including regional nappe boundaries as well as nw se n s and ne sw trending recent brittle structures the kinematic consistency between these structures and the pattern of seismicity suggests that active tectonics may force dsgsds although field evidence and numerical models indicate slope debuttressing related to deglaciation as a primary triggering mechanism

relationships between radium and radon occurrence and hydrochemistry in fresh groundwater from fractured crystalline rocks north carolina usa article i nfo article history accepted 21 october 2008 naturally occurring radionuclides uranium radium and radon major dissolved constituents and trace elements were investigated in fresh groundwater in 117 wells in fractured crystalline rocks from the piedmont region north carolina usa chemical variations show a general transition between two water types 1 slightly acidic ph 5 0 6 0 oxic low total dissolved solids tds waters and 2 near neutral oxic to anoxic higher tds waters the uranium radium and radon levels in groundwater associated with granite rolesville granite are systematically higher than other rock types gneiss metasedimentary and metavolcanic rocks water chemistry plays a secondary role on radium and radon distributions as the 222 rn 226 ra activity ratio is correlated with redox sensitive solutes such as dissolved oxygen and mn