the origin and mechanisms of salinization of the lower jordan river the chemical and isotopic 87 sr 86 sr 11 b 34 ssulfate 18 owater 15 nnitrate compositions of water from the lower jordan river and its major tributaries between the sea of galilee and the dead sea were determined in order to reveal the origin of the salinity of the jordan river we identified three separate hydrological zones along the flow of the river 1 a northern section 20 km downstream of its source where the base flow composed of diverted saline and wastewaters is modified due to discharge of shallow sulfate rich groundwater characterized by low 87 sr 86 sr 0 7072 34 ssulfate 2 high 11 b 36 15 nnitrate 15 and high 18 owater 2 to 3 values the shallow groundwater is derived from agricultural drainage water mixed with natural saline groundwater and discharges to both the jordan and yarmouk rivers the contribution of the groundwater component in the jordan river flow deduced from mixing relationships of solutes and strontium isotopes varies from 20 to 50 of the total flow 2 a central zone 20 50 km downstream from its source where salt variations are minimal and the rise of 87 sr 86 sr and so4 cl ratios reflects predominance of eastern surface water flows 3 a southern section 50 100 km downstream of its source where the total dissolved solids of the jordan river increase particularly during the spring 70 80 km and summer 80 100 km to values as high as 11 1 g l variations in the chemical and isotopic compositions of river water along the southern section suggest that the zarqa river 87 sr 86 sr0 70865 11 b25 has a negligible affect on the jordan river instead the river quality is influenced primarily by groundwater discharge composed of sulfate rich saline groundwater cl 31 180 mm so4 cl0 2 0 5 br cl2 310 3 87 sr 86 sr0 70805 11 b30 15 nnitrate 17 34 ssulfate4 10 and ca chloride rift valley brines cl 846 1500 mm br cl 6 8 10 3 87 sr 86 sr0 7080 11 b40 34 ssulfate4 10 mixing calculations indicate that the groundwater discharged to the river is composed of varying proportions of brines and sulfate rich saline groundwater solute mass balance calculations point to a 10 contribution of saline groundwater cl282 to 564 mm to the river a high nitrate level up to 2 5 mm in the groundwater suggests that drainage of wastewater derived irrigation water is an important source for the groundwater this irrigation water appears to leach pleistocene sediments of the jordan valley resulting in elevated sulfate contents and altered strontium and boron isotopic compo sitions of the groundwater that in turn impacts the water quality of the lower jordan river copyright 2004 elsevier ltd

catalogue of palaeomagnetic directions and poles from fennoscandia archaean to tertiary abstract palaeomagnetic data from fennoscandia ranging from the archaean to the tertiary have been compiled into a catalogue the data are presented in table format listing precambrian data according to tectonomagmatic blocks and late precambrian phanerozoic data according to geological periods each pole is graded with the modified briden duff classification scheme the catalogue complete to the end of 1988 contains 350 entries from 31 tectonomagmatic blocks and or geological periods normal and reversed polarity data are listed separately to allow polarity asymmetries to be studied each entry also has an indexed abstract summarizing relevant information such as the age of the rock the age of the natural remanent magnetization and the basis for the assigned reliability grade all the data are stored in the palaeomagnetic data bank which will be updated annually with new data the catalogue is the basic source of data for the microcomputer based palaeomagnetic database for fennoscandia now being compiled

origin and residence time of groundwater in the tadla basin morocco using multiple isotopic and geochemical tools summary groundwater resources in the tadla basin stem from surface water recharge and different groundwater inflows forming a multilayered aquifer system which hosts one of morocco s most important groundwater reservoirs the hydrodynamic infrastructure i e the relationship between all regional aquifers recharge and the residence time of waters poses a serious challenge for current water management and future exploitation in aiming for a long term sustainable utilization a combined hydrogeologic and isotopic investigation using hydrochemical and isotopic tracers such as 18 o 2 h 3 h 13 c and 14 c was carried out in order to determine the sources of water recharge to the aquifers the groundwater flow system and the residence time of these waters more than one hundred point measurements throughout the study area in varying wells boreholes springs and rivers were investigated chemical compositions of the groundwater indicate an important influence by the host carbonate rocks from each of the tadla aquifers stable isotope results indicate the existence of two groups of groundwater corresponding to the unconfined aquifer in the north and the confined aquifer in the south the 18 o 2 h 3 h and 14 c data indicate that the high atlas mountains in the south and east of the basin which are characterized by high rainfall and low 18 o and 2 h values are currently the major source of recharge for the tadla aquifers a significant recharge zone lies in the northern part of the basin where all the aquifers outcrop the confined zones show depleted 18 o values corresponding to the signature of recharge water from the atlas mountains moreover all isotope data demonstrated clearly that the tassaout springs which are located in the southwest of the basin and were previously interpreted as representing natural outlet of the deep aquifers are comprised of young waters with depleted 18 o and 2 h signatures suggesting a high altitude recharge from the atlas mountain in contrast the unconfined parts of the aquifers show higher values of 18 o indicating an evaporation phenomenon which occurs during infiltration or recharge from irrigation the mixing process of old and recent waters is confirmed by 14 c and 3 h the isotopic data also indicates probable interaction and flow between the different aquifers the isotopic and hydrochemical data is therefore essential in confirming possible mixing relationships between aquifers whereas traditional hydraulic data is not capable to provide a quantitative assessment of these relationships the data generated in this study will certainly encourage the revision and improvement of the current hydrological water resources model for the tadla basin the results provide a framework for development of a comprehensive management plan in which water exploitation shifts towards areas with modern recharge and where young and high quality groundwater is found

saltwater intrusion modelling in jorf coastal aquifer south eastern tunisia geochemical geoelectrical and geostatistical application marine intrusion is the most serious problem facing the coastal jorf shallow aquifer located in south eastern tunisia on the mediterranean sea jorf aquifer is intensively exploited to supply the growing needs of agriculture and domestic sectors this work proposes a multidisciplinary investigation involving hydro geochemical geoelectrical survey and geostatistical techniques for modelling the saltwater intrusion for this purpose 36 water samples were conducted and analysed electric conductivity ph total dissolved solids and major ions were measured and analysed pie and durov diagrams q mode hierarchical cluster and geostatistical analysis were considered to identify the main groundwater mineralization processes results revealed that the na cl ca so4 is the dominant water type suggesting that dissolution of halite and gypsum was the main mineralization source of groundwater in the central and southern part of study area however saltwater intrusion was shown to control groundwater quality essentially in coastal areas variographic analyses were used to select the variographic model that best fits the spatial development of apparent resistivity kriged apparent resistivity profiles showed an abnormal decrease of resistivity values in the coastal zone implying highly saline water because of seawater intrusion apparent resistivity values also decrease considerably in the faulted areas suggesting a contribution of faults to seawater intrusion finally saltwater mixing ratio was computed for each sample and a refined seawater intrusion map was developed copyright 2012 john wiley sons ltd

the uplift magnetisation record in the central scandinavian caledonides results from basic igneous complexes abstract to identify the palaeomagnetic record acquired during slow post orogenic uplift and cooling in the central part of the scandinavian caledonides we have investigated four separated synorogenic basic complexes in the middle and upper allochthons a shallow n s axis of magnetisation is common to three of these bodies and therefore postdates all major tectonism it is defined in the mosjoen gabbro d i 7 3 n 23 samples 95 5 0 in the sulitjelma gabbro d i 20 9 n 22 samples 95 6 6 and the rana norite d i 9 16 n 19 samples 95 7 9 no vestige of this uplift remanence is recognised in the lyngen ophiolite where a characteristic remanence of d i 65 43 n 19 samples 95 10 6 is recorded the possibility that the n s shallow axis of magnetisation is of mid carboniferous age is considered and rejected instead it is attributed to the interval of post tectonic cooling of the caledonian nappe pile between synorogenic events dated ca 420 ma and the uplift to surface levels defined by later devonian events it corresponds closely to an axis of magnetisation extensively represented within the metamorphic caledonides and scotland and believed to record a post tectonic thermochemical event subordinate components record mesozoic overprinting events and relict caledonian magnetisations which have escaped replacement during this thermo tectonic event the latter collectively imply a rapid movement from high to low palaeolatitudes in late ordovician and early silurian times

origin of groundwater salinity and hydrogeochemical processes in the confined quaternary aquifer of the pearl river delta china summary the pearl river delta prd located in the coastal area of south china contains a large confined quaternary aquifer this aquifer has been identified to have high concentrations of total dissolved solids ranging from 1 g l in the inland area to 26 8 g l near the southeast shoreline this work aims to investigate the origin of groundwater salinity and the major hydrogeochemical processes controlling the groundwater evolution in the confined basal aquifer of the prd a total of 40 boreholes were drilled in the prd during 2007 2009 and groundwater samples were collected for major ion ca 2 mg 2 na k nh 4 cl so 2 4 and hco 3 and isotope d 18 o d 2 h 3 h d 13 c and 14 c analyses these analyses demonstrate that groundwater in the confined basal aquifer is recharged by local rainwater and seawater and seawater is the major salinity source for groundwater the contribution of seawater varies from less than 1 in the inland areas to 74 near the shoreline so 2 4 reduction and methanogenesis occur in this reducing confined aquifer the results of ion exchange show that mg 2 exchanges mainly with the nh 4 ion which is derived from the mineralization of sedimentary organic matter ion exchange between na

hydrochemical and isotopic characterisation of eastern haouz plain groundwater morocco the groundwater of eastern haouz of morocco is an important source for the high density population and intensive agricultural activity in the area the water demand here is increasing year by year groundwater levels measured in the study area show that the water table is quite deep 40 50 m and that the groundwater flow is closely following the surface topography major ion chemistry was made on 40 groundwater samples and about 20 samples among them were used for stable isotope measurements a large variation is found between the minimum and the maximum values of different ions the dominant cation na concentration varied between 18 and 1 159 mg l and the anion cl varied between 53 and 2 176 mg l samples from schist and triassic sediments are relatively more mineralised thus unsuitable for drinking as well as agricultural purposes groundwater within the plains alluvium is relatively less mineralised than the other older formations however hydrochemical values of many samples collected from alluvium are also not in the potable range owing to the natural and the anthropogenic contamination hence hydrochemical data of the study area show geological control on water quality apart from salinity about 25 of the samples have higher nitrate content than the drinking water permissible limit stable isotope measurements show that groundwater recharge to the phreatic aquifer is controlled by local conditions

groundwater mineralisation processes in mediterranean semi arid systems cap bon north east of tunisia hydrogeological and geochemical approaches the groundwater of the korba plain represents major water resources in tunisia the plio quaternary unconfined aquifer of the cap bon north east tunisia is subject to the intensive agricultural activities and high groundwater pumping rates due to the increasing of the groundwater extraction the degradation of the groundwater quality is characterized by the salinization phenomena groundwater were sampled and analysed for physic chemical parameters ca2 mg2 na k cl so42 hco3 no3 ph electrical conductivity ec and the temperature t the hydrochemical analysis is coupled with the calculation of the saturation indexes si gypsum si halite si calcite and si dolomite ionic derivation and with the ion correlations compared to chloride concentrations na cl ca2 cl and mg2 cl ratios seawater fractions in the groundwater were calculated using the chloride concentration those processes can be used as indicators of seawater intrusion progression ec methods were also conducted to obtain new informations on the spatial scales and dynamics of the fresh water seawater interface of coastal groundwater exchange the mixing zone between freshwater and saltwater was clearly observed from the ec profile in the investigated area where a strong increase in ec with depth was observed corresponding to the freshwater and saltwater interface results of hydrochemical study revealed the presence of direct cation exchange linked to seawater intrusion and dissolution processes associated with cations exchange these results together with ec investigation indicated that the groundwater is affected by seawater intrusion and is still major actor as a source of salinization of the groundwater in korba coastal plain further isotopic and hydrological investigations will be necessary to identify and more understood the underlying mechanisms copyright 2012 john wiley sons ltd

the origin of geothermal waters in morocco multiple isotope tracers for delineating sources of water rock interactions abstract the geochemical and isotopic strontium boron radium oxygen hydrogen variations of geothermal waters from five different regions in morocco were investigated in order to evaluate the sources of solutes and the mechanisms of water rock interaction during 2008 to 2010 twenty two geothermal water samples were collected from the southern central and northern parts of morocco the water samples were analyzed for major and trace elements stable isotopes 18 o 2 h naturally occurring radionuclides 226 ra 228 ra 224 ra and isotopes of dissolved strontium 87 sr 86 sr and boron 11 b the moroccan geothermal waters exhibited a wide range of salinity ranging from 590 to 25 000 mg l with predominance of chloride sodium sulfate calcium and bicarbonate ions integration of the geochemical and isotope data suggests that the geothermal waters in morocco originate from recharge of meteoric water and water rock interactions the predominance of chloride and sodium and the relatively low br cl ratios 3 combined with ca so 4 ratios 1 suggest that halite and sulfate gypsum anhydrite minerals are the major rock sources for mineralization of the geothermal waters the variations of 87 sr 86 sr ratios 0 7076 0 7122 and 11 b 5 3 29 3 were used to distinguish two rock sources 1 dissolution of marine sulfate carbonate rocks with sr isotope composition that correspond to the expected ratios in seawater during time of deposition and 2 non marine sources with higher 87 sr 86 sr and 11 b presumably from interactions with clay minerals and shale rocks the variations of radium isotopes indicate that the alpha recoil of the parent nuclides on the host rocks caused mobilization of the short lived 224 ra and 228 ra to the geochemical waters the low 228 ra 226 ra ratios activity ratios of 0 04 0 14 measured in the geothermal waters mimic the th u ratios in the source rocks which indicate predominance of uranium over thorium our data show that some of the geothermal waters in morocco are characterized by high salinity and in some systems also by elevated radioactivity above international drinking water standards which limits their utilization for agricultural and domestic applications adequate treatment is therefore required to use geothermal waters in morocco as an alternative or additional water source other geothermal waters with low mineralization can be utilized as alternative resource for the agricultural and domestic sectors without any restrictions

assessment of groundwater quality for drinking and irrigation purposes a case study of peddavanka watershed anantapur district andhra pradesh india in india the quantity and quality of water available for irrigation is variable from place to place assessment of water quality has been carried out to determine the sources of dissolved ions in groundwater quality of groundwater in a 398 km2 peddavanka watershed of a semi arid region of south india is evaluated for its suitability for drinking and irrigation purposes the middle proterozoic cuddapah supergroup and kurnool group of rocks underlie most of the watershed the main lithologic units consist chiefly of quartzite limestone and shale seventy six water samples were collected from open wells and bore holes water samples were collected representative of the post monsoon winter and pre monsoon summer the quality assessment is made through the estimation of ca2 mg2 na k cl so 4 2 co 3 2 hco 3 total hardness as caco3 tds ec and ph based on these analyses parameters like sodium adsorption ratio sodium residual sodium carbonate non carbonate hardness potential salinity kelley s ratio magnesium ratio index of base exchange and permeability index were calculated according to gibbs ratio samples in both seasons fall in the rock dominance field the overall quality of waters in the study area in post monsoon season is high for all constituents ruling out pollution from extraneous sources

hydrogeochemical and isotopic characterization of the groundwater in the chari baguirmi depression republic of chad the chari baguirmi groundwater in the republic of chad is undergoing a steady deterioration both qualitative and quantitative due to climatic severe droughts and anthropogenic overexploitation constraints however this major water resource has not been to date the object of any comprehensive scientific investigation to fill this gap and consider a sustainable exploitation a hydrodynamic and hydrochemical study was undertaken this aquifer is located south of lake chad and displays a significant natural piezometric depression piezometric campaign on an area of 70 000 km2 bounded by lake chad the chari river the mountains of guera and the dunes of harr was conducted to understand the hydrodynamics of the groundwater water samples were collected on 124 points scattered over the study area hydrochemical and isotopic analyses 18o and 2h were achieved on all samples the interpretation of hydrochemical data was done using the piper diagram the multivariate analysis hierarchical ascending classification the index of base exchanges and ratios of na cl na so4 cl so4 br cl sr ca the hydrochemical results coupled with groundwater isotopes data allowed to understand the processes that govern the mineralization and the origin of groundwater salinity these investigations allowed on the one hand to differentiate between two poles of water mixing and second to demonstrate that the mineralization process and origin of salinity in the center of depression are both related to the lithology of the geological formations crossed by groundwater flow and climatic events causing evaporation of water from the aquifer

ophiolitic melange separates ortho and para tectonic caledonides in western ireland the nature of the contact between the orthotectonic late pre cambrian to cambrian and the paratectonic ordovician and silurian caledonides has long been a source of discussion in western ireland this junction occurs in a complex zone which crops out along the southern shores of clew bay county mayo where dalradian middle cambrian and ordovician arenig rocks are separated by a pre silurian rock unit termed the deer park complex1 fig 1 the complex contains both meta sedimentary and meta igneous rocks and has been variously interpreted as representing a pre caledonian basement ridge1 an imbricate thrust zone2 related to the development of a major fault system the fair head clew bay line3 or an arenig ophiolite4 we report here geological geochemical and geophy sical studies on the deer park complex which indicate that it is a northerly dipping melange unit containing the components of a dismembered ophiolite these findings imply a source of ophiolitic rocks to the north possibly within the orthotectonic caledonides

fluorine in formation waters alberta basin canada abstract fluorine is a common minor constituent of formation waters throughout the alberta basin and it was detected in each of the 469 samples analyzed for it contents range up to 22 mg l with an arithmetic mean of 1 83 mg l and a median value of 1 20 mg i there is a trend toward increased mean and median contents of f from the shallower cooler less saline formation waters to the deeper hotter more saline formation waters this trend parallels a trend of increasing saturation with respect to fluorite with most of the less saline formation waters being undersaturated with respect to fluorite at the same time the major portion of f occurs as f in the less saline formation waters with increasing amounts held as mgf as the ca content ionic strength and temperature increase complexes between al and f and vo and f account for only a relatively minor portion of the complexed f a significant portion of the f in high salinity formation waters from marine strata could well have originated from the initial seawater however it is speculated that water rock reactions with bentonite or bentonitic shales may have to be invoked to account for the very high contents of f in the less saline formation waters from some of the shallow cooler non marine aquifers of the upper cretaceous post colorado aquifer aquitard system finally it is possible to use knowledge of the distribution of f in formation waters from individual aquifers to check on the correctness of f determinations primarily when formation waters of similar composition show saturation with respect to fluorite and in the same case to predict the f content of formation waters in the alberta basin for which only the appropriate major ions have been determined

a palaeomagnetic study of the basal gneiss region and jotun nappe complex central southern scandinavian caledonides summary in the southern sector of the scandinavian caledonides a metamorphic gneiss complex the basal gneiss region or bgr underthrusts a nappe complex of precambrian granulites the jotun nappe in an assemblage collectively recording orogenic events culminating in the scandian upper silurian and lower devonian episode palaeomagnetic study of a large regional sample spanning the combined outcrop identifies properties strongly controlled by metamorphic retrogression to amphibolite and greenschist facies low blocking temperature ibt components in the bgr have e directions with a mean of d 69 1 60 n 19 sites 95 7 0 sporadic higher blocking temperature components define a dual polarity northeast negative southwest positive ne sw axis with a mean of d 42 1 24 20 sites 95 8 1 granulite facies rocks in the jotun nappe yield a high quality palaeomagnetic record reflected in high lqn values and dominated by medium and high blocking temperature hbt components a dual polarity a axis defines a palaeofield migration from ne to e during uplift and cooling of this terrane with a predominance of normal polarities a smaller population of ibt b components show e directions distributed along the mesozoic palaeofield migration path for eurasia and probably acquired during brittle tectonic events of this age a magnetizations from 86 sites define mean south pole positions between 301 e 2 n and 325 e 10 s linked to uplift related cooling following the climactic scandian orogenic episode and dated at 420 400 ma from the collective geological and radiometric evidence both the outward and return segments of an apw loop may be represented the polar swathe correlates with i a higher blocking temperature component from the bgr ii the uplift magnetization record in the western orthotectonic caledonides of scotland and iii primary magnetizations from the siluro devonian molasse facies in britain this study shows that the westerly extension of the apw path identified by british siluro devonian data is not peculiar to that crustal segment but applies to continental europe and presumably to laurentia as well the pattern of remanence acquisition within the caledonides suggests contrasting zones of thermal and thermochemical remanence with the latter probably linked to fluid migration consequent upon orogenic loading

volatile control of contrasting trace element distributions in peralkaline granitic and volcanic rocks anomalous enrichments of zr 500 ppm zn 100 ppm nb 25 ppm y 60 ppm th 20 pm u 5 ppm lree 230 ppm and hree 35ppm and high rb sr 5 characterize peralkaline granites in contrast to their peraluminous and calc alkaline equivalents within the peralkaline suite comenditic and pantelleritic volcanics exhibit two to five fold increases in the concentrations of these trace elements over comagmatic granites these cannot be explained by crystal liquid fractionation processes and require the evolution of a sodium enriched fluid corresponding trace element increases in the granites in areas of alkali metasomatism support this argument and reflect the partial confinement of this volatile phase within the high level magma chambers ree studies in particular might eventually allow an evaluation of the role of cl versus f and co3 complexing in the evolution of the volatile fluid

early carboniferous unroofing in western norway a tale of alkali feldspar thermochronology abstract 40ar 39ar thermochronologic data from an extensional detachment zone in western norway document punctuated late paleozoic through mesozoic tectonothermal activity diffusion and thermal modeling of alkali feldspars sampled in a profile through the detachment replicate laboratory argon release patterns when feldspars comprise three or four diffusion domains with differing activation energies that represent high intermediate and low closure temperatures these domains correspond to distinct changes in late paleozoic cooling rates 1 slow cooling at 0 4 2 2 c m yr from ca 380 360 ma 2 rapid cooling at 15 c m yr in late devonian early carboniferous time 360 340 ma 3 slow cooling at 0 4 1 7 c m yr after ca 340 ma with partial argon loss in permian and late jurassic early cretaceous times the early carboniferous rapid cooling event recorded by the feldspars links the western norway margin to contemporaneous unconformities regional extension basin inversion and igneous activit

a model for the deep structure of the moine thrust zone seismic refraction and electrical conductivity profiles across northern scotland together with geological and other geophysical data are interpreted in terms of the deep structure of this part of the orthotectonic caledonides our preferred interpretation is that the moine thrust zone extends to the base of the crust and the caledonian front is steep this contrasts with recently proposed ultra thin skinned solutions the results of the recently completed moist deep seismic reflection experiment should inter alia test our hypothesis in order to test the geometrical feasibility of our interpretation balanced sections have been constructed to illustrate the crustal evolution of the region during the caledonian orogeny these sections permit estimates to be made of crustal shortening thickening and erosion our model requires that the n highlands were once overlain by major exotic nappes which by analogy with nw newfoundland may have been ophiolitic the proposed regional structural pattern comprises a duplex of crustal dimensions we suggest that crustal duplex development is an important mechanism in the orogenic deformation of previously thinned and extended passive continental margins

geochemical and isotopic oxygen hydrogen carbon strontium constraints for the origin salinity and residence time of groundwater from a carbonate aquifer in the western anti atlas mountains morocco summary groundwater in many arid basins particularly in developing countries is the only available water resource that sustains local communities yet information on the basic hydrological parameters and the sustainability of the groundwater exploitation are often lacking this study investigates the origin of groundwater from the lower cambrian carbonate aquifer of the lakhssas plateau in the anti atlas mountains of southwestern morocco the study aims to reveal the origin of the groundwater salinity sources and the residence time of the water the study is based on a comprehensive geochemical and isotopic oxygen hydrogen carbon and strontium investigation of groundwater from different parts of the basin the hydrochemical and isotopes results indicated three types of groundwater in the lakhssas plateau 1 thermal water in the southern part of the basin with solute composition that reflects dissolution of calcium sulfate and calcium carbonate minerals 2 low temperature groundwater at the southern margin of the basin with low salinity chloride content up to 100 mg l and chemical composition that is expected from equilibrium with limestone dolomite rocks and 3 low temperature groundwater in the northern western and eastern margins of the basin with a wide range of salinity chloride up to 800 mg l the different water types had also different stable isotope composition the thermal water was depleted in 18 o and 2 h 18 o as low as 7 6 relative to the southern 5 9 to 5 3 and northern waters 5 7 to 3 8 the differences in 18 o and 2 h between the southern and northern waters are related to elevation that induced fractionation of oxygen and hydrogen isotopes in recharge water originated from coastal moisture the data suggest that the high salinity in groundwater from the northern western and eastern margins of the lakhssas plateau is related to the presence of schist rocks in these areas the distinctive low na cl and br cl ratios coupled with high silica contents and high 87 sr 86 sr ratios up to 0 713 in the saline groundwater provide additional evidences for the link between salinity and the schist rocks in contrast the thermal water had relatively low 87 sr 86 sr ratio 0 7089 which is identical to the secular seawater sr isotope ratio during the early cambrian period and presumably reflects interaction with the early cambrian carbonate and sulfate aquifer rocks in the northern and southern groundwater the 87 sr 86 sr ratios were higher and correlated with the mg ca ratios inferring mixing between the early cambrian limestone and other rocks with higher 87 sr 86 sr such as the schist rocks the radiocarbon data showed 14 c activities ranging from 6 pmc in the thermal water to 62 pmc in the southern water age modeling corrected for dissolution of the carbonate rocks with dead carbon simulated mean residence time of 10 15 ka bp for the thermal water and a range of 0 to 3 ka bp for the northern and southern waters depending on the used models the integration of the data enables us to establish a conceptual model for the origin of groundwater in the lakhssas plateau 1 recharge to the aquifer from relatively heavy isotope depleted recharge water presumably during wetter conditions about 10 15 ka bp the recharge water interacted at high depth with limestone and calcium sulfate minerals and emerged to the surface as thermal water at the southern part of the basin 2 more recent recharge from coastal moisture originated from the atlantic ocean the stable isotope composition of groundwater was controlled by the elevation of their recharge areas recharge at higher elevation particularly in the southern margin resulted in lower 18 o and 2 h values 3 the recharge water interacted with the carbonate aquifer rocks particularly with calcite and dolomite minerals in areas of exposure of schist rocks the water rock interaction induced salinization of the groundwater overall our data reveal that the limited water resources in this semi arid zone of morocco could be in some parts less renewable and also saline future exploitation of this basin will have to account the salinity factor and the suggested contribution of water recharged some thousands years ago

major northwest directed caledonian thrusting and folding in precambrian rocks northwest mayo ireland structural mapping of the north west mayo inlier has investigated the kinematics of ductile fault and shear zones within the dalradian and pre dalradian rocks the area is characterized by an intense east to southeast trending elongation direction pre caledonian deformation is preserved as west northwest trending sinistral mylonite zones these are cross cut by grenville pegmatites and by undated mafic dykes subsequent deformation has been influenced by the majorbasement structures during the caledonian deformation the pre existing sinistral structures were reactivated coaxially as steep sinistral shear zones deforming the mafic dykes major northwesterly verging thrusts are widespread in flat lying zones which occur over much of the inlier these are interpreted as d2 in age the s2 fabric is the dominant fabric and contains an east to northeast trending mineral lineation the southeastern part of the inlier is characterized by very large scale wavelengths of kilometres reclined d2 folding this is interpreted as a crustal scale ramp zone in the vicinity of this ramp there is evidence of earlier f1 folds which are possibly the product of ramprelated deformation all of these structures are interpreted as the product of northwest verging thrusting with crustal scale frontal and lateral ramps

geochemistry and rb sr geochronology of associated proterozoic peralkaline and subalkaline anorogenic granites from labrador anorogenic granites of middle to late proterozoic age in the davis inlet flowers bay area of labrador are subdivided on the basis of petrology and geochemistry into three coeval suites two of these are high temperature anhydrous hypersolvus granites a peralkaline aegirine sodic calcic to sodic amphibole bearing suite and a non alkaline fayalite pyroxene bearing suite the third is a group of non alkaline subsolvus hornblende biotite bearing granites associated with the hypersolvus peralkaline suite is a group of genetically related syenites and quartz syenites the granites cut ca 3 000 ma old archaean gneisses as well as elsonian layered basic intrusions of the nain complex one of these a crudely layered mass which ranges in composition from gabbro to diorite and monzonite appears to be related to the syenites the peralkaline granites and some of the syenites are extremely enriched in the high field strength elements such as y zr nd as well as rb ga and zn and have low abundances of ba sr and most of the transition elements in contrast the non alkaline hypersolvus and subsolvus granites do not show the same degree of enrichment concentration of the highly charged cations in the peralkaline suite is believed to be the result of halogen rich fluid activity during fractionation of the magma the sodic evolution trend in the peralkaline suite is reflected mineralogically by the development of aegirine and aegirine hedenbergite solid solutions and by a spectacular amphibole compositional range from katophorite through winchite richterite riebeckite to arfvedsonite and ferro eckermannite accessory phases which are ubiquitous in these rocks include aenigmatite astrophyllite fluorite monazite and zircon the non alkaline hypersolvus granites typically contain iron rich phases such as fayalite eulite ferrosilite hedenbergite and annite rich biotite in the subsolvus granites amphiboles range in composition from edenite through common hornblende to actinolite and also coexist with annite rich biotite

oblique rifting and sequential faulting in the jurassic development of the northern north sea abstract jurassic structural development of the northern north sea has characteristics of oblique rifting this is interpreted to result from an obliquity between jurassic nw se to wnw ese directed extension and a preexisting n s trending zone of deformation related to permo triassic rifting and thinning of the crust the zone of maximum jurassic extension i e the viking and sogn grabens defines a narrow 25 40 km depression which trends diagonally nne ssw across a broader 130 150 km permo triassic basin the jurassic rift zone consists of a system of ene chelon rift segments with changing symmetry along strike bounded by faults oblique to the overall graben envelope sequential jurassic fault development as well as the interference between n s and ne sw striking faults are explained within the context of oblique rifting the early late bajocian oxfordian rift stage was dominated by reactivation of n s striking major faults whereas a number of coeval but smaller faults have a ne sw orientation ne sw striking faults show increasing importance during the jurassic stretching phase and major faults defining this orientation accommodated most of the kimmeridgian volgian extension faults striking nesw are observed to cross cut earlier n s trending faults they interfere with n s trending faults to define faultblocks with rhombohedral shape and they are associated with partial collapse of crestal areas of n s oriented fault blocks to form structural terraces

caracterisation des eaux de l aquifere turonien du bassin du tadla maroc par le rapport des concentrations molaires sr2 ca2 resume l analyse des variations de la concentration du strontium dissous dans les eaux souterraines de la nappe des calcaires cretaces du bassin marocain du tadla qui s etend sur 10 000 km2 nous conduit a en proposer une explication les formations geologiques du turonien qui affleurent sur la peripherie du bassin sauf sur la bordure sud est chevauchee par le haut atlas peuvent etre environnees par des evaporites au toit ou a la base des contaminations de l eau par dissolution et par melange d eaux sulfatees et d eaux carbonatees de l aquifere sont decelees nous demontrons que le rapport sr 2 ca 2 est un moyen de distinguer la nature du reservoir aquifere ainsi que les origines des relations hydrodynamiques quatre groupes geographiques ont ete individualises selon la valeur du rapport sr 2 ca 2 un groupe septentrional en affleurement 0 8 1 un autre en regime captif 1 2 1 7 avec des anhydrites associees aux calcaires un groupe avec une nappe a facies sulfate 3 24 subdivise en deux sous groupes l un au ne influence par le cenomanien gypseux 7 24 et l autre au s marque a la fois par le senonien lagunaire toit de l aquifere et par le cenomanien substratum un cinquieme groupe distinct 2 84 correspond aux eaux superficielles sulfatees de l oued oum er rbia alimente par les eaux sulfatees issues des horizons evaporitiques triasiques de l atlas

dinosaurs and other fossil vertebrates from fluvial deposits in the lower cretaceous of southern tunisia remains of dinosaurs and other vertebrates sharks bony fishes coelacanths turtles crocodilians pterosaurs are reported from the chenini formation of the tataouine region in southern tunisia the formation is part of the continental intercalaire a succession of continental deposits of early to late cretaceous age distributed over the whole of north africa and the sahara it consists of bar and channel deposits of broad rivers that flowed nnw from the mid sahara region towards the southern shore of tethys dinosaur bearing units in the continental intercalaire have been dated to the hauterivian to cenomanian and the chenini formation is possibly albian in age dinosaur fossils include abundant teeth of the theropods carcharodontosaurus and spinosaurus as well as postcranial elements of theropods and a medium sized sauropod a tooth of an ornithocheirid is the first report of a pterosaur from the region the dinosaur bones and teeth were transported some distance and deposited in a channel lag associated with less damaged locally derived material such as fern fronds coprolites fish teeth and scales and crocodilian scutes

a magnetic deep structural geology interpretation of ireland a new 10 nt compilation of magnetic data for ireland and the immediately adjacent sea area shows distinct geophysical provinces of characteristic magnetic signature separated by major magnetic linears which can be related to important geological lines in the far northwest there is a structurally coherent grampian tectonic thermal zone bounded to the southeast by the fair head clew bay line between the fair head clew bay line and the western extension of the southern uplands line which forms the northern margin to the southern uplands of scotland is a segmented zone of relatively small magnetic anomalies and geological bodies of mixed crustal affinity grampian massifs lower palaeozoic sedimentary basins bounded by major shear faults relics of lower palaeozoic oceanic and related crust and possible older microcontinent fragments these separate areas have quite individual structural and metamorphic histories there is good evidence for the grampian massifs having undergone significant lateral movement during lower palaeozoic times and it can be inferred that many of the now adjacent bodies are only docked the original position of each block is now not known in the far southeast of ireland are relics of a cadomian craton which are now tectonically imbricated with lower palaeozoic rocks this is probably the segmented margin of the stable cadomian craton which is inferred beneath wales and south britain between the southern uplands line and the northernmost extent of the relics of the southern craton is a zone of deep seated low amplitude magnetic anomalies and major linears these are about 30 oblique to the southern margin of this vestiges of the iapetus ocean zone but are nearly parallel with the northern margin

chronologie rb sr et k ar du granite peralcalin du lac brisson labrador central nouveau quebec a rb sr whole rock isochron gives an age of 1189 32 ma for the peralkaline granite of lake brisson k ar data on amphiboles yield an age of 1163 21 ma which further confirms our dating such an age allows the corresponding magmatism to be attributed to the late stage of the gardar anorogenic province which till now has been unknown in labrador

karst landscape and hydrology in morocco research trends and perspectives moroccan karst has been the subject of study over the last two decades as a system where landforms interact with groundwater springs and human action the literature review gone through in this article focuses on international publications including french journals it shows the complexity of the karst area and its local model diversity the regimes of the aquifers landforms and springs were reported in most mountain terrains and the local interactions between the karst aquifer karst springs landforms and human action were discussed even the rif mountain presents some karst aspects mainly in its central part the atlas domain is more dominated by karst the substrate types tectonics altimetry climate and vegetation roles are important in karst dynamics human factors impact the landscapes and the equilibrium of the hydro karst system via resources overuse and management indicators of the present day disequilibrium were evoked turbidity of water in karst springs geotechnical problems erosion of the soil etc these problems will be more complex in the future due to the human density increase and probable intense human activity in the rural areas sustainable management is therefore a challenging priority in the karst domain

rare element mineralization related to precambrian alkali granites in the arabian shield five examples of disseminated rare element mineralization with sufficient resource potential to warrant exploration all are characterized by enrichment in a suite of granitophile elements which typically includes nb ta sn rare earth elements y th u and zr but they differ in size geometry mode of occurrence and lithology two types of mineralization the jabal sa id type is characterized by high total iron to total alkali ratios and high k 2 o na 2 o ratios the ghurayyah type is characterized by major oxide abundances approximating those of typical alkali granites both types evolved from alkali granite magmas formed by high temperature dry melting of late proterozoic island arc crust indicated resources range from 6 million metric tons jabal tawlah and umm al birak through or 20 million metric tons jabal sa id and jabal hamra to 440 million metric tons ghurayyah the highest average grades from nb 3 400 ppm sn 380 ppm y 5 200 ppm and zr 37 000 ppm occur at jabal tawlah the highest ta grades 200 ppm at ghurayyah and the highest u 130 ppm and th 830 ppm grades at jabal sa id modified journal abstract

the age and tectonic significance of dolerite dykes in western norway coast parallel dykes in sw norway primarily of permo triassic age have been linked regionally to the early tectonic evolution of the norwegian continental shelf we demonstrate from palaeomagnetic data mean declination 206 1 inclination 30 1 a 95 11 8 that dolerite dykes in the coastal sunnfjord region of western norway and immediately west of the devonian basins are also of permian c 250 270 ma age and not lower or pre devonian as previously advocated the sunnfjord dykes appear to be contemporaneous with dykes from sw norway at sotra 262 6 ma and the oldest dykes from sunnhordland 260 280 ma and geochemical data attest to a transition from sub alkaline to alkaline magmatism at the dawn of the mesozoic the sunnfjord dykes are not simple records of e w extension and magma intrusion but instead represent significant mid late permian time markers within a complex zone of fault activation and rejuvenation late mesozoic cenozoic magnetic overprinting mean declination 348 6 inclination 68 9 a 95 12 and metamorphic alteration documented by these dykes are directly dependent upon proximity to major e w brittle faults south of the hornelen devonian basin hence some motion and related fluid activity do post date dyke intrusion the e w high angle normal or oblique slip faults can be regionally traced offshore to the oygarden fault zone onshore these faults truncate the hornelen low angle detachment which in turn cuts folded d evonian strata these observations along with evidence for permian and late jurassic cretaceous extension from the nearby dalsfjord region demonstrate important reactivation of a late to post caledonian detachment and high angle fault system in western norway

application of multiple isotopic and geochemical tracers for investigation of recharge salinization and residence time of water in the souss massa aquifer southwest of morocco summary groundwater and surface water in souss massa basin in the west southern part of morocco is characterized by a large variation in salinity up to levels of 37 g l 1 the high salinity coupled with groundwater level decline pose serious problems for current irrigation and domestic water supplies as well as future exploitation a combined hydrogeologic and isotopic investigation using several chemical and isotopic tracers such as br cl 18 o 2 h 3 h 87 sr 86 sr 11 b and 14 c was carried out in order to determine the sources of water recharge to the aquifer the origin of salinity and the residence time of water stable isotope 3 h and 14 c data indicate that the high atlas mountains in the northern margin of the souss massa basin with high rainfall and low 18 o and 2 h values 6 to 8 and 36 to 50 is currently constitute the major source of recharge to the souss massa shallow aquifer particularly along the eastern part of the basin localized stable isotope enrichments offset meteoric isotopic signature and are associated with high nitrate concentrations which infer water recycling via water agricultural return flows the 3 h and 14 c data suggest that the residence time of water in the western part of the basin is in the order of several thousands of years hence old water is mined particularly in the coastal areas the multiple isotope analyses and chemical tracing of groundwater from the basin reveal that seawater intrusion is just one of multiple salinity sources that affect the quality of groundwater in the souss massa aquifer we differentiate between modern seawater intrusion salinization by remnants of seawater entrapped in the middle souss plains recharge of nitrate rich agricultural return flow and dissolution of evaporate rocks gypsum and halite minerals along the outcrops of the high atlas mountains the data generated in this study provide the framework for a comprehensive management plan in which water exploitation should shift toward the eastern part of the basin where current recharge occurs with young and high quality groundwater in contrast we argued that the heavily exploited aquifer along the coastal areas is more vulnerable given the relatively longer residence time of the water and salinization processes in this part of the aquifer

orthogonal joint systems in the bergen area southwest norway and their regional significance abstract joint orientation measurements are reported from the bergen district southwest norway the prevailing joint systems form two near vertical near orthogonal sets striking preferentially nw se and ne sw the orientation of these fissure systems is consistent with fissure systems dissecting the surface formations precambrian to quaternary throughout britain and northwest france they also show general agreement with lineaments in southern norway as revealed by landsat imagery it is suggested that the orthogonal joint network represents a fundamental tectonic structure originally implanted into the mobile outer layer of the earth in precambrian time the network has been repeatedly reactivated throughout the earth s dynamic tectonic history it was probably formed in a shear regime caused by torsional deformation associated with rotation of large scale lithospheric units which is still operating today

effect of land use and urbanization on hydrochemistry and contamination of groundwater from taejon area korea abstract taejon metropolitan city located in the central part of south korea has grown and urbanized rapidly the city depends heavily on groundwater as a water resource because of ubiquitous pollution sources the quality and contamination have become important issues for the urban groundwater supply this study has investigated the chemical characteristics and the contamination of groundwater in relation to land use an attempt was made to distinguish anthrophogenic inputs from the influence of natural chemical weathering on the chemical composition of groundwater at taejon groundwater samples collected at 170 locations in the taejon area show very variable chemical composition of groundwater e g electrical conductance ranges from 65 to 1 290 s cm most groundwater is weakly acidic and the groundwater chemistry is more influenced by land use and urbanization than by aquifer rock type most groundwater from green areas and new town residential districts has low electrical conductance and is of ca hco 3 type whereas the chemical composition of groundwater from the old downtown and industrial district is shifted towards a ca cl no 3 so 4 type with high electrical conductance a number of groundwater samples in the urbanized area are contaminated by high nitrate and chlorine and exhibit high hardness the epco 2 that is the co 2 content of a water sample relative to pure water was computed to obtain more insight into the origin of co 2 and bicarbonate in the groundwater the co 2 concentration of groundwater in the urbanized area shows a rough positive relationship with the concentration of major inorganic components the sources of nitrate chlorine and excess co 2 in the groundwater are likely to be municipal wastes of unlined landfill sites leaky latrines and sewage lines chemical data of commercial mineral water from other jurassic granite areas were compared to the chemical composition of the groundwater in the taejon area factor analysis of the chemical data shows that the hco 3 and no 3 concentrations have the highest factor loadings on factor 1 and factor 2 respectively factors 1 and 2 represent major contributions from natural processes and human activities respectively the results of the factor analysis indicate that the levels of ca 2 mg 2 na cl and so 4 2 derive from both pollution sources and natural weathering reactions

elucidating the sources and mechanisms of groundwater salinization in the ziz basin of southeastern morocco in the ziz basin located in arid area in southeastern morocco surface waters are scarce and local populations are entirely dependent on groundwater resources for drinking and irrigation in order to evaluate the main factors controlling the origin and salinization of groundwater resources we have investigated the chemical and stable isotope compositions of groundwater and surface water in different areas in the ziz basin upstream and downstream from the hassan addakhil dam which is the major man made reservoir in the basin a large variation in water quality was observed specifically an increase in salinity from north upstream to the reservoir with tds 460 mg l to south downstream tds 16 000 mg l in the northern portion of the basin the low saline groundwater is composed primarily of ca2 and mg2 due to dissolution of carbonate formations in the high atlas mountains in contrast the major dissolved consequents of saline waters are cl so4 2 and na apparently due to dissolution of evaporite minerals gypsum and halite in some areas elevated nitrate contents imply anthropogenic contamination derived from local agriculture the stable isotopes data 18o 8 6 to 8 3 and 2h 55 7 to 53 8 indicate that the high atlas mountains upstream of the reservoir constitute the major source of water to the ziz basin given that this arid basin is entirely dependent on groundwater resources long term salinization of groundwater in the ziz basin could lead to negative effects and reduction of the local agricultural productivity in addition to the degradation of drinking water quality in this region

complete remagnetization of some permian dykes from western norway induced during burial uplift abstract stable paleomagnetic directions in four basaltic dykes and in some associated caledonian metamorphic rocks define high latitude mesozoic paleomagnetic pole positions which are not compatible with the k ar age of 250 my determined for the dykes a monotonic increase of 40 occurs in the potassium content of samples taken across a dyke 32 cm wide this is accompanied by only a 1 2 variation in the k ar age of the samples suggesting the absence of any significant level of initial argon titanomagnetite grains having bulk compositions around x 0 6 have suffered extensive low temperature alteration forming assemblages of ferri rutile granules in a matrix of pure magnetite the complete remagnetisation of both the dykes and the associated country rocks is probably an expression of a vrm acquired at elevated temperatures 150 500 c at the emplacement depth of the dykes a stable remanent magnetisation was locked in during uplift of the area probably related to the kimmerian basin development in the adjacent north sea and the epeirogenic uplift of western fennoscandia

numerical analysis of hydrogeochemical data a case study alto guadalentin southeast spain abstract this study examines the spatial variability of the factors obtained from the application of correspondence analysis to a hydrogeochemical data set the goal was to synthesize the hydrogeochemical information using this multivariate statistical technique by setting a series of factors which clarified the main properties of one aquifer then a geostatistical framework to obtain a probabilistic assessment of groundwater quality was established experimental and theoretical semivariograms of the selected factors considered as regionalized variables were computed these variographic information and factor values in the experimental sites were used in the ordinary kriging which provides unbiased and linear estimates of the regionalized variables these estimates were used to compile maps of the chosen factors which explain their spatial distribution the selected case study was the alluvial aquifer of alto guadalentin which is situated in southeast spain in the internal zones of betic cordilleras these waters are chiefly so4 and cl types but hco3 facies are common in the central sector of the basin high temperature acid ph problems of overexploitation and pollution by co2 gas characterise these waters available groundwater quality monitoring data were used to calibrate the numerical model the present study focused on setting the main physical and chemical attributes and establishing the spatial pattern of groundwater quality and the temporal changes in this pattern

groundwater modelling and marine intrusion in the semi arid systems cap bon tunisia this article studies the effect of drought and pumping discharge on groundwater supplies and marine intrusion in the korba aquifer cap bon peninsula tunisia the groundwater modelling system has been used to model the groundwater flow and to simulate the seawater intrusion the calibration is based on the groundwater levels in the steady state from 1963 and in the transient state from the groundwater levels from 1963 to 2005 the main objective is to quantify the components of the groundwater mass balance and to estimate the hydraulic conductivity distribution the impact of pumping discharge on the groundwater level evolution has been examined by two pumping scenarios p1 no 8420 and p2 no 8862 wells the hydrodynamic modelling shows the increasing drawdowns after 14 years of pumping 4 m in p1 well and about 5 m in p2 well below sea level the drawdowns are accompanied by the inverse hydraulic gradient the numerical model was used to discuss the management of the groundwater resources of cap bon as the population continues to grow and the demand for groundwater pumping intensifies beyond the 1963 level it can be expected that the actual extent of seawater intrusion in the future would be more severe than the model prediction better strategies for groundwater development and management will be necessary to protect the freshwater aquifers to the marine intrusion copyright 2011 john wiley sons ltd

u pb ages of ophiolites and arc related plutons of the norwegian caledonides implications for the development of iapetus u pb zircon ages are reported for four ophiolites and three crosscutting arc related plutons from the norwegian caledonides plagiogranite differentiated from gabbro of the karmoy ophiolite is dated at 493 7 4 ma whereas arc related trondhjemite cutting this ophiolite crystallized at 485 2 ma a crosscutting clinopyroxene phyric gabbro intrusion is dated at 470 9 5 ma by near concordant magmatic titanite sphene and discordant u rich 2903 6677 ppm zircon lower intercepts of 247 68 and 191 70 ma defined by the plagiogranite and clinopyroxene phyric gabbro best fit lines may reflect a real low t alteration rift related event

a displaced and metamorphosed peralkaline granite related to the late proterozoic labrador and gardar suites the doolough granite of county mayo northwest ireland the chemically and lithologically distinct doolough granite from the annagh division in northwest county mayo ireland includes part of the northwesternmost exposures of precambrian basement in europe the doolough granite is similar to precambrian granitic intrusions found in labrador and southwest greenland although its age of emplacement at u pb in zircon is slightly younger than the canadian intrusions a reconstruction of the pre iapetus disposition of the eastern laurentian margin suggests that the doolough granite was probably emplaced at a location sufficiently close to both southwest greenland and labrador for it to have formed part of the same magmatic province during a period of restricted crustal extension that preceded the grenville event

a late precambrian rift related igneous suite in western newfoundland a granite that yields a u pb zircon age of 602 10 ma is associated with mafic and silicic volcanic rocks and metamorphic equivalents near deer lake in western newfoundland the granitic rocks are named the round pond granite and the combined granite volcanic suite is assigned to the hughes lake complex all of the rocks are contained in the hughes lake structural slice that occurs above other allochthonous rocks and the autochthonous cambrian ordovician carbonate sequence of western newfoundland the round pond granite is cut by metadiabase dykes mafic volcanic rocks interpreted as coeval with the dykes occur along the southeast side of the granite a thick sequence of arkosic metagreywackes and psammitic to pelitic schists of the mount musgrave group occurs stratigraphically above the mafic volcanic rocks regional correlations imply that the mount musgrave group is of late precambrian early cambrian age thus setting an upper stratigraphic limit to the age of the hughes lake complex perthitic and

geological control on the origin of fresh groundwater in the otindag desert china abstract the present study has explored the origin of fresh groundwater in the otindag desert china using environmental tracers the results characterize hydrochemical and isotopic properties of groundwater in this middle latitude desert of arid asia clarifying their spatial distribution and linkage with climatic topographic and geologic settings and interpreting the groundwater source and chemical evolution hydrogeochemical and isotopic signals suggest that groundwater recharge in the desert is isolated from seasonal and regional variations in meteorological forcing stable isotopic data 2h 18o and radioactive isotopic data 3h indicate that the desert aquifer is dominated by high altitude cold water originating from the highland mountains that border the desert to the east and south variography shows that the dip of the main xilamulun fault is a dominant control on the groundwater flow implying that the tectonic settings are more important than climatic and topographical settings to explain the origin of groundwater in the desert this means that the origin of fresh groundwater in the desert is maily controlled by geological structures this study provides a new perspective into the origin and evolution of groundwater resources in the middle latitude deserts of the arid asia

from orogen to passive margin constraints from fission track and u th he analyses on mesozoic uplift and fault reactivation in sw norway the post caledonian tectonic history and landscape evolution of southwestern norway are poorly understood primarily owing to the lack of onshore post devonian sediments to bridge this knowledge gap low temperature thermochronological techniques were applied to investigate vertical movements in the upper crust new apatite fission track and apatite and zircon u th he analyses on samples from southwestern norway yielded permian to jurassic triassic to cretac eous and carboniferous to triassic ages respectively thermal history modelling indicates rela tively high cooling rates 2 3 8 cm a 21 throughout permian to early jurassic times since the jurassic samples from coastal areas have remained close to the surface and were reheated to 30 50 8c during sedimentary burial in the cretaceous inland samples experienced lesser amounts of permo triassic exhumation continued to cool slowly 1 8 cm a 21 throughout the jurassic cretaceous and did not reach the surface until the cenozoic both fission track and u th he ages are offset across faults highlighting the importance of fault activity throughout the mesozoic in combination with previously published results the new data suggest that the geo morphological evolution of southwestern norway is closely connected to rift and post rift tec tonics related to north sea and north atlantic rifting the topographic relief was most likely repeatedly rejuvenated during periods of tectonic activity

geochronology of the baie verte peninsula newfoundland implications for the tectonic evolution of the humber and dunnage zones of the appalachian orogen u pb analyses of zircon from the burlington granodiorite suggest intrusion at c 460 465 ma hornblende and biotite from central portions of the pluton record markedly younger sup 40 ar sup 39 ar plateau dates 410 420 ma which are interpreted to date contact metamorphic effects associated with the widespread emplacement of silurian devonian igneous suites northern portions of the burlington granodiorite are polydeformed and regionally metamorphosed hornblende and biotite from this terrane yield sup 40 ar sup 39 ar plateau ages of 345 350 ma u pb analyses of zircon from the dunamagon granite indicate emplacement at c 440 460 ma thereby providing an upper limit for tectonic juxtapositioning of the humber and dunnage zones along the baie verte line similar ages are also recorded by hornblende and biotite throughout northerly portions of the mings bight humber zone and pacquet harbour dunnage zone groups these results indicate that the tectonic evolution of the baie verte line as polygenetic and involved 1 regionally significant tectonothermal activity prior to the middle ordovician and 2 middle to late paleozoic tectonothermal activity centered along easterly segments of the baie verte line the regional metamorphism associated with this orogenic activity altered primary u pb and rb sr isotopic systems within various igneous suites exposed in northeastern portions ofmore the burlington peninsula which may explain some inconsistent geochronological results previously obtained 54 references 6 figures 5 tables less

suitability assessment of deep groundwater for drinking and irrigation use in the djeffara aquifers northern gabes south eastern tunisia the multilayered djeffara aquifer system south eastern tunisia has been intensively used as a primary source to meet the growing needs of the various sectors drinking agricultural and industrial purposes the analysis of groundwater chemical characteristics provides much important information useful in water resources management detailed knowledge of the geochemical evolution of groundwater and assessing the water quality status for special use are the main objective of any water monitoring study an attempt has been made for the first time in this region to characterize aquifer behavior and appreciate the quality and or the suitability of groundwater for drinking and irrigation purposes in order to attend this objective a total of 54 groundwater samples were collected and analyzed during january 2008 for the major cations sodium calcium magnesium and potassium anions chloride sulfate bicarbonate trace elements boron strontium and fluoride and physicochemical parameters temperature ph total dissolved salts and electrical conductivity the evolution of chemical composition of groundwater from recharge areas to discharge areas is characterized by increasing sodium chloride and sulfate contents as a result of leaching of evaporite rock in this study three distinct chemical trends in groundwater were identified the major reactions responsible for the chemical evolution of groundwater in the investigated area fall into three categories 1 calcite precipitation 2 gypsum and halite dissolution and 3 ion exchange based on the physicochemical analyses irrigation quality parameters such as sodium absorption ratio sar percentage of sodium residual sodium carbonate residual sodium bicarbonate and permeability index pi were calculated in addition groundwater quality maps were elabortaed using the geographic information system to delineate spatial variation in physico chemical characteristics of the groundwater samples the integration of various dataset indicates that the groundwater of the djeffara aquifers of the northern gabes is generally very hard brackish and high to very high saline and alkaline in nature the water suitability for drinking and irrigation purposes was evaluated by comparing the values of different water quality parameters with world health organization who guideline values for drinking water piper trilinear diagram was constructed to identify groundwater groups where the relative major anionic and cationic concentrations are expressed in percentage of the milliequivalent per liter meq l and it was demonstrated that the majority of the samples belongs to so4 cl ca na cl so4 na ca and na cl hydrochemical facies as a whole all the analyzed waters from this groundwater have revealed that this water is unsuitable for drinking purposes when comparing to the drinking water standards salinity high electric conductivity sodium adsorption ratio and sodium percentages indicate that most of the groundwater samples are inappropriate for irrigation the sar vary from medium s2 to very high s4 sodicity therefore the water of the djeffara aquifers of the northern gabes is dominantly of the c4 s2 class representing 61 23 of the total wells followed by c4 s3 and c4 s4 classes at 27 27 and 11 5 of the wells respectively based on the us salinity classification most of the groundwater is unsuitable for irrigation due to its high salt content unless certain measures for salinity control are undertaken

palaeomagnetism of a caledonian ophiolite complex karmoy southwest norway abstract the palaeomagnetism of the karmoy ophiolite suite emplaced at the southwest extremity of the scandinavian caledonides in middle upper ordovician times is described low intensities of magnetisation and low q n values in the bulk of the constituent facies are linked to the effects of low grade metamorphism but ultramafic pods that have experienced serpentinisation yield well defined single component magnetisations a predominant a component of magnetisation isolated in 35 samples yields a mean of d i 51 58 95 5 this population is discrete from a subsidiary b component recognised in 17 samples with a mean direction of 145 63 95 8 a minor c component d i 330 60 95 8 is also identified and small numbers of anti parallel components are identified in each case an upper ordovician ignimbrite from kattnakken northeast of karmoy yields an in situ component of d i 270 38 together with similar components recognised elsewhere this mean d direction is most closely compatible with directions recognised in upper silurian lower devonian rocks from the scottish sector of the caledonides it is interpreted as an overprint of this age but may include a component of local rotation two interpretations are considered for the remanence record in the karmoy complex the a component could record the influence of a thermal event linked to uplift of the continental margin and development of the adjoining north sea basin in mesozoic times if this margin has been tilted seawards by 20 since magnetisation no plausible tectonic model can bring the b component into conformity with the post 300 ma apparent polar wander apw path and it is alternatively proposed that both the a and b components record upper ordovician post emplacement remanences with this interpretation the data complement a range of palaeomagnetic results from middle upper ordovician igneous and metamorphic rocks from north atlantic bordering terranes yielding intermediate to high palaeolatitudes and contrasting with older and younger data collectively they imply that the iapetus ocean had effectively closed by these times and that large apw movements took place between mid ordovician and mid silurian times

noble gases stable isotopes and radiocarbon as tracers of flow in the dakota aquifer colorado and kansas abstract a suite of chemical and isotope tracers dissolved noble gases stable isotopes of water radiocarbon and cl have been analyzed along a flow path in the dakota aquifer system to determine likely recharge sources ground water residence times and the extent of mixing between local and intermediate flow systems presumably caused by large well screens three water types were distinguished with the tracers each having a very different history two of the water types were found in south eastern colorado where the dakota is poorly confined the tracer data suggest that the first group recharged locally during the last few thousand years and the second group was composed of ground water that recharged earlier during a cooler climate presumably during the last glacial period lgp and mixed aged water the paleotemperature record archived in this groundwater system indicates that south eastern colorado was about 5 c cooler during the lgp than during the late holocene similar temperature changes derived from dissolved noble gases in other aquifer systems have been reported earlier for the south western united states the third water type was located down gradient of the first two in the confined dakota in western and central kansas groundwater residence time of this water mass is on the order of 10 4 10 5 yrs and its recharge location is near the colorado and kansas border down gradient of the other water types the study shows the importance of using multiple tracers when investigating ground water systems

groundwater evolution in the continental intercalaire aquifer of southern algeria and tunisia trace element and isotopic indicators abstract the geochemical processes taking place along an 800 km flow line in the non carbonate continental intercalaire aquifer ci aquifer in north africa are described using chemical major and trace element and isotopic indicators the aquifer is hydraulically continuous from the atlas mountains in algeria to the chotts of tunisia and the geochemical evidence corroborates this the highest discharge temperature is 73 c but silica geothermometry indicates a maximum temperature of 94 c at depth chloride concentrations increase from 200 to 800 mg l 1 and the br cl ratios confirm the dissolution of non marine evaporites or interstitial waters as the main source of salinity fluoride concentrations are low and are likely to be derived from rainfall recording oscillations in source radiocarbon ages except near outcrop are at or near detection limits and the 18o and 2h values indicate a cooler recharge regime with rainfall having lower primary evaporation than today this is shown by the fact that mean isotope ratios of ci waters are around 3 lighter than the present day weighted mean value for rain major ion ratios and most trace elements indicate that despite the complex structure and stratigraphy uniform evolution with continuous water rock interaction takes place along the flow lines which are only disturbed near the tunisian chotts by groundwater converging from additional flow lines the ageing of the water can also be followed by the smooth increase in several indicator elements such as li k and mn which are least affected by solubility controls similarly the influence of marine facies in the tunisian sector may be recognised by the changing mg ca and higher br cl as well as trace element indicators the groundwaters are oxidising up to 300 km from outcrop dissolved o2 has persisted for at least 20 ka and within this zone the concentrations of several elements forming oxy anions such as u and cr increase and no3 remains conservative beyond 300 km from outcrop the groundwaters are reducing and contain high fe concentrations the basin contains huge reserves of fresh brackish waters but these need careful development due to the limiting high salinity and scaling tendency resulting from the high temperatures and mineral super saturation caused during abstraction as well as high concentrations of some harmful elements such as cr in the oxidising section

salinization processes in the unconfined aquifer of bou areg ne morocco a geostatistical geochemical and tomographic study hydrogeological and geochemical data in conjunction with the results of an electrical imaging tomographic survey were examined to determine the main factors and mechanisms controlling the groundwater chemistry and salinity of the unconfined aquifer of bou areg on the mediterranean coast of ne morocco in addition statistical and geochemical interpretation methods were used to identify the distribution of the salinity multivariate statistical analysis cluster and principal component factors revealed the main sources of contamination groups a b and c in the cluster analysis and factors 1 3 factor 1 ce cl k so42 and mg2 factor 2 ca2 hco3 and ph factor 3 no3 represent the signature of seawater intrusion in the coastal zone the influence of marly gypsum outcrops in the upstream zone and anthropogenic sources respectively the ionic delta the ionic ratio the saturation index and stuyfzand s method were applied to evaluate geochemical processes the results obtained indicate on the one hand the phenomenon of salinization in both the coastal and the upstream zones and on the other the dilution of groundwater by recharge cation exchange is shown to modify the concentration of ions in groundwater locally with respect to salinization processes in the coastal zone the results of electrical imaging tomography show that salinity increases both with depth and laterally inland from the coastline due to seawater intrusion

chemistry of waters from selected caves in slovakia a reconnaissance study the chemical composition of water samples was studied from different caves in slovakia the water samples were collected from caves of two karst regions 1 the demanovsk cave system dcs situated in the low tatra mountains northern slovakia which is mainly formed of limestone and dolomites and 2 the slovakian karst to the southeast is formed of limestone a considerable difference between water from the two regions was shown the waters from the dcs that were controlled by vadose water percolating through different types of host rocks contained more mg ions than those from the slovakian karst caves whereas the concentration of so4 was controlled by the dissolution of displacive gypsum and or oxidation of pyrite the distribution of no3 in the studied samples was random hence nitrates probably derived from few pollution sources the total mineralization of the water was covariant with calcite and aragonite saturation indices in general both parameters are higher in the slovakian karst caves than in the dcs it is controlled probably by differences in climatic conditions soil and plant covers between these two regions the main goal of this article is to characterize the major ion water chemistry within the studied caves as well as some microelements the results have confirmed the dominant role of the bedrock petrography in forming the general chemistry of cave waters

the highland border rocks and their relation to marginal basin development in the scottish caledonides it has long been known that the highland border includes an assemblage of altered serpentinites gabbros spilitic lavas ferruginous and manganiferous cherts black phyllites quartzose clastics and amphibolites new work confirms that many of these rocks represent a dismembered tectonically emplaced ophiolite of caledonian age which originated in a narrow oceanic basin within or bordering the dalradian sedimentary pile the ophiolitic rocks were expelled from the basin as thrust sheets transecting d1 structures studies in the sw highlands suggest emplacement during d2 synchronous with se translation of the tay nappe this implies that the ophiolite originated in the n the highland border rocks are seen as marginal to a long lived northward dipping subduction zone within the southern uplands the evolution of the ballantrae ophiolitic complex the midland valley and the dalradian sedimentary basin are considered within this framework

identifying the origin of groundwater and ﬂow processes in complex landslides affecting black marls insights from a hydrochemical survey the super sauze mudslide is a persistently active slow moving landslide occurring in the black marl outcrops of the french south alps it has been intensively studied since the early 1990s geotechnical geomorphological geophysical and hydrological investigations have led to a better understanding of the processes governing the landslide motion water ows inside the system have been proven to have a major impact to look closer at the processes involved and especially to gain a better idea of the origin and pathways of the waters a hydrochemical study was carried out from may 2003 to may 2004 the groundwater was sampled during ve eld campaigns spread uniformly over the year groundwater from a network of boreholes was collected as well as spring waters from the fractured bedrock in situ black marl and from the moraine aquifer above the landslide results showed that the groundwater chemistry could not be fully explained by rainfall recharge or simple water matrix equilibrium a contribution of saline waters coming from the bottom of a thrust sheet overhanging the landslide was required to get the observed high mineralization on a ow line the hydrochemical evolution was related to both soil matrix equilibrium and deep water sources coming up to the surface by means of major faults the bedding planes and the schistosity hydrochemical anomalies made it possible to point out such contributions locally it was shown that water chemistry and landslide activity were closely related this hydrochemical investigation also enabled us to better de ne the hydrosystem limits copyright 2006 john wiley sons ltd

origin and salinity of groundwater from interpretation of analysis data in the mining area of oumjrane southeastern morocco under the arid climate in the southern sub saharan catchments of morocco groundwater is the only permanent water supply usually the groundwater is scarce because of the low recharge however the mining activities in oumjrane area eastern anti atlas mountains reveal that water resources are relatively abundant in the fissured ordovician aquifer to understand this phenomenon geochemical and isotopic investigations were carried out in the region the results show that the quality of water is variable in superficial and deep aquifers the specific conductivities range from 0 44 to 10 ms cm most groundwater samples from the deep aquifer indicate high salinity low ph and co2 anomalies geochemical analyses show that groundwater concentrations are mainly controlled by i evaporite dissolution halite and gypsum ii cation exchange with clay minerals iii silicate hydrolysis and iv dedolomitisation carbonate precipitation takes place in the groundwater issuing from the mine sector the discharge is estimated at 386 t year downstream of the bounhass mine moreover stable isotope 2h and 18o and chemical analyses reveal a clear difference between the alluvial and deep aquifers they also show a local recharge for the alluvial aquifer from saghro inliers low isotope ratios are found in the ordovician formation aquifer indicating a deep water circulation these waters could originate from the high atlas and or saghro mountains and flow through fissures and fault networks connections to regional faults and veins may play a role in it as well as the proximity of the major contact with the high atlas

chemostratigraphic correlation structure and sedimentary environments in the dalradian of the nw co mayo inlier nw ireland a thorough geochemical survey of the dalradian rocks in the nw mayo inlier has shown that each formation has a characteristic geochemical signature within regional geochemical trends that vary systematically with stratigraphic age this geochemical characterization enables correlation between geographically and tectonically isolated stratigraphic successions in the nw mayo inlier an almost complete succession of late proterozoic grampian appin and argyll group dalradian rocks structurally overlies earlier basement annagh division gneisses in structural blocks bounded by caledonian thrusts extensional low angle faults and steeply dipping faults grampian appin group relationships are better seen here than anywhere else in scotland or ireland but no tayvallich subgroup or southern highland group dalradian rocks are present comparison with chemostratigraphic data from scottish dalradian rocks reveals broadly similar chemical trends with time suggesting that the geological evolution of the dalradian took place in a related depositional environment probably an unbroken continental margin along the entire dalradian outcrop seen in both scotland and ireland

a conceptual model for groundwater circulation using isotopes and geochemical tracers coupled with hydrodynamics a case study of the lez karst system france abstract geochemical and isotopic tracers 18o 2h 87sr 86sr and 13ctdic were used to constrain origins and chemical evolution of groundwater in a mediterranean karst system the lez spring is the main perennial outlet of this karst system and supplies the metropolitan area of montpellier southern france with drinking water groundwater samples were collected at the lez spring and surrounding springs and wells under different hydrodynamic conditions during two hydrological years from june 2008 until may 2010 the results show that multiple hydrological compartments interact through an important network of fractures and faults they notably reveal connections between the main jurassic limestone aquifer and the overlying cretaceous valanginian compartment and between the surface and deep levels of the karst system isotopic tracers provided information about atmospheric recharge origins lithological signatures and chemical evolution of waters long residence time groundwaters issued from deep layers have a triassic hydrochemical fingerprinting being enriched in 13ctdic and characterized by high concentrations in cl as well as high sr ca mg ca and 87sr 86sr ratios evidences suggest that these waters mix with waters from the lower layers of the main jurassic aquifer constitute an intermediate storage compartment prone to rise through piston flow mechanism a two end member hydrograph separation based on ec tds was used to determine the proportion of the deep compartment s contribution to the lez spring outflow on average over the study period the main aquifer compartment and the deep aquifer compartment are estimated to contribute 92 6 and 7 4 of groundwater flow at the lez spring respectively

early paleozoic orogenic collapse tectonic stability and late paleozoic continental rifting revealed through thermochronology of k feldspars southern norway southern norway was subjected to contractional orogenesis and subsequent extensional collapse during the early to middle paleozoic when baltica collided with laurentia resulting in the caledonian orogen the largely unknown post caledonian paleozoic thermal history of the crust in southern norway has been assessed through application of multiple diffusion domain thermal modeling of k feldspar 40ar 39ar data samples were collected along a 250 km e w traverse from the internides of the orogen along the western coast near bergen through a series of middle to upper crustal nappes to the east the k feldspar thermal models which complement published mica and hornblende 40ar 39ar data are consistent with rapid cooling at the end of the caledonian orogenic cycle when early devonian 400 ma extensional collapse resulted in exhumation through mainly midcrustal conditions following extensional collapse a period of relative tectonic and thermal stability may have prevailed until 300 ma the k feldspar modeling suggests that southern norway entered a new phase of relatively rapid cooling a few c ma in the permo carboniferous and that the increase in cooling rate was diachronous across the traverse the onset of this cooling phase occurs at about the time of the earliest faulting and magmatism in the oslo graben to the southeast the increase in cooling rate may also indirectly date the onset of the first important rift phase and associated sedimentation in the north sea graben system the distribution of permian and younger fission track ages in both southern continental norway and its marginal basin sediments is consistent with the permo carboniferous rapid cooling recorded in the k feldspars the simplest explanation for the late paleozoic increase in cooling rate is that rifting around the margin of southern norway has resulted in a decrease in the base level and an increase in the rate of erosional denudation resulting in essentially uniform exhumation of 2 4 km along the traverse

sources of salinity and boron in the gaza strip natural contaminant flow in the southern mediterranean coastal aquifer isotopic 87 sr 86 sr d 11 b d 18 o d 2 h and d 34 sso4 compositions of groundwater from the southern mediterranean coastal aquifer israel and the gaza strip in order to elucidate the origin of salinity and boron contamination the original salinity in the eastern part of the aquifer is derived from discharge of saline groundwater from the adjacent avedat aquitard na cl 1 high b cl so4 cl and hco3 87 sr 86 sr 0 7083 d 11 b 48 although the d 18 o d 2 h slope is identical to that of the avedat aquitard the geochemical data suggest that dissolution of pedogenic carbonate and gypsum minerals in the overlying loessial sequence generated the ca rich solution that triggered base exchange reactions and produced na and b rich groundwater the geochemical data show that most of the salinization process in the gaza strip is derived from the lateral flow of the na rich saline groundwater superimposed with seawater intrusion and anthropogenic nitrate pollution the methodology of identification of multiple salinity sources can be used to establish a long term management plan for the gaza strip and can also be implemented to understand complex salinization processes in other similarly stressed coastal aquifers

hydrogeochemical processes in the groundwater environment of muktsar punjab conventional graphical and multivariate statistical approach understanding the hydrogeochemical processes that govern groundwater quality is important for sustainable management of the water resource a study with the objective of identifying the hydro geochemical processes and their relation with existing quality of groundwater was carried out in an intensively cultivated district of punjab india the study approach includes conventional graphical plots and multivariate analysis of the hydrochemical data to define the geochemical evaluation of aquifer system based on the ionic constituents water types hydrochemical facies and factors controlling groundwater quality the results suggest that different natural hydrogeochemical processes like simple dissolution mixing weathering of carbonate minerals locally known as kankar silicate weathering and ion exchange are the key factors in the pre monsoon which was superseded by leaching processes loaded with anthropogenic inputs in the post monsoon limited reverse ion exchange has been noticed at few locations of the study area especially in pre monsoon periods there was a significant effect of monsoon observed in terms of hardness and the significant amount of area with temporary hardness ca2 mg2 hco 3 type in the pre monsoon switched to permanent hardness domain i e ca2 mg2 cl type by the post monsoon at most factor analyses substantiate the findings of conventional graphical plots and provide greater confidence in data interpretation thus the study highlights the descriptive capabilities of conventional and multivariate techniques as effective tools in groundwater evaluation

the thrust and shear zones of the moine thrust zone and the nw scottish caledonides the caledonian thrust belts of nw scotland exhibit many features typical of foreland fold and thrust belts the major structures propagated westwards towards the foreland the thin carapace of cambro ordovician sediments being accreted in imbricate and duplex zones beneath the major thrust sheets on a broad scale the rules of thrust geometry are obeyed but many local anomalies are found particularly in the assynt region in assynt several large fault bounded gravity spreading structures surge zones have been identified extensional faults have been traced into strike slip and then contractional faults there are zones of extensional and contractional imbricate faults and extensional and contractional ductile flow similar structures have been found along the length of the moine thrust belt suggesting that gravity spreading was an important mechanism during the later stages of movement within the main caledonian fold belt there are several major tectonic slides which are recognized by a local increase in intensity of deformation the majority are nw verging and were originally gently dipping in the highlands se of the great glen there are early major se verging recumbent folds associated with considerable crustal thickening reflected in high pressure 12kbar metamorphism many of the major slides may have formed by spreading away from this thickened crust the caledonian deformation and metamorphism occurred later in the moines and moine thrust zone than in the dalradian and grampian moines to the se of the great glen this may reflect different levels of deformation alternatively it may argue for a large strike slip displacement on the great glen fault juxtaposing crustal blocks which had experienced different ages of caledonian deformation and metamorphism the late movement on the moine thrust involved spreading from an area of thickened caledonian crust formed either by the stair step trajectory of the basal thrust to the moines and or by thickening due to intrusion of large masses of late caledonian granites

terrane amalgamation in the clew bay region west of ireland the caledonides of the west of ireland provide a well exposed and well mapped example of an oblique collision zone the east northeast trending deer park and achill beg fault system is a crustal scale ductile sinistral strike slip duplex of late ordovician age imbricating late precambrian granulite facies lower crustal rocks near eclogite facies supracrustal rocks up to amphibolite facies dalradian metasedimentary rocks and greenschist facies cambro ordovician rocks this fault system is correlated with a pre devonian component of the highland boundary fault system in southern scotland in the clew bay area the high pressure low temperature facies metamorphic rocks in tectonic contact with greenschist facies cambro ordovician rocks are together interpreted as an accretionary prism complex related to northwestward directed subduction both of these are allocthonous terrains with respect to the dalradian terrane to the north north west mayo to the south the cambro ordovician rocks docked with a probable dalradian block containing ultramafic intrusives deer park complex during the late ordovician the deer park complex and south mayo trough linked earlier during the arenig silurian and lower middle devonian redbed successions sit unconformably on the metamorphic rocks deposition and deformation of these cover rocks was controlled by oblique strike slip movements on the leek fault whose strike swings from west northwest to north northeast following earlier basement trends as it is traced eastwards from clew bay the leek fault system may be correlated with the leannan fault of northwest donegal a splay of the great glen fault system of central scotland east of clew bay this sinistral shear generated local dilation on the more northerly trending bend of the leek fault lower and middle old red sandstone redbeds were developed here the west northwest trend of the leek fault in clew bay acted as a compressional bend during these sinistral movements and transpressional southwest directed thrusting developed in silurian rocks post middle old red sandstone pre late tournaisian dextral displacement on the leek fault reversed this pattern with transtension in clew bay allowing intrusion of small carbonated peridotite bodies into silurian rocks and easterly directed thrusting of middle old red sandstone rocks east of the bay on the transpressional north south bend a tectonic model for the region is presented here this model involves a northwestward directed subduction system 150 to 750 km of arenig sinistral strike slip movement and eastwards insertion of the connemara block with formation of the ordovician south mayo trough as a pull apart basin subsequently a further 130 to 650 km eastward displacement of rocks took place south of the deer park fault in later ordovician times the magnitudes of these estimates are directly proportional to an assumed maximum wavelength of 1500 km for promontories on the original laurentian margin and using the current juxtaposition of terranes a minimum wavelength of 300 km is inferred

geochemical and isotopic investigations on groundwater residence time and flow in the independence basin mexico abstract the independence basin in the semi arid guanajuato state of central mexico is facing serious groundwater resources deficiency due to an increasing demand linked to a rapid population growth and agricultural development this problem is aggravated by an inadequate evaluation of groundwater resources in the region geochemistry and isotopic tracers were used in order to investigate the groundwater flow system and estimate the groundwater residence time the groundwater is characterized by low salinity with some exceptions associated to a contribution of more saline groundwater from deep formations the predominant reactions are co 2 gas dissolution carbonate dissolution albite weathering kaolinite and chalcedony precipitation six principal hydrochemical zones were recognized which provided information on plausible recharge sources and groundwater chemical evolution the 14 c concentration varies between 19 and 94 pmc the high 14 c values indicating recent recharge are observed at the basin margins and a trend to lower 14 c values is observed along the modern groundwater flow paths the groundwater residence time according to radiocarbon estimations ranges between recent and 11 ka the residence time distribution matches the regional important discharge zones west in the basin center from dolores hidalgo and southwest from doctor mora hydrochemical tracers are in general agreement with the predeveloped and current hydraulic head configuration however show some inconsistencies with the predeveloped head in the downgradient areas which means that the impact by gradually increasing groundwater extraction during the last decades is reflected on radiocarbon age distribution geochemical evidences imply that the recharge input from the northern basin area is insignificant

geochemistry processes of the djeffara palaeogroundwater southeastern tunisia abstract environmental stable and radioisotopes have been employed to identify the origin the recharge mode and geochemical processes controlling groundwater quality in southeastern tunisia where population is growing and water demand for domestic and irrigation activities is increasing water balance assessment constitutes a serious concern about sustainability of water resources isotopic characterization using stable isotopes 2 h 18 o and 13 c and radiocarbon 14 c of the djeffara aquifer system lead to characterization of carbon origin in the system and identification of geochemical processes that control water chemistry in addition statistical methods were used to identify the distribution of the salinity multivariate statistical analysis principal component analysis pca and hierarchical cluster analysis hca revealed the main sources of groundwater mineralization the main reactions responsible for the hydrochemical evolution in the djeffara groundwater fall into three categories 1 mixing process 2 dissolution of salts and 3 cation exchange process djeffara groundwater shows markedly low 14 c activities confirming that the aquifer has limited modern recharge the modelling of isotopic evolution of the dissolved inorganic carbon dic pool indicates the presence of additional source of carbon 13 c 5 typical for mantle co 2 which can explain the variability of 13 c and 14 c activities observed in dic pool of groundwater samples

hydrogeology and geochemistry of the multilayered confined aquifer of the pisa plain tuscany central italy the pisa plain contains a multilayered confined aquifer made up of pleistocene sands and gravels the groundwater from the wells tapping these horizons are generally of poor quality they exhibit significant tds relatively high cl content and considerable hardness during geothermal prospecting of the pisa plain about 80 wells ranging in depth from 20 to 250 m were sampled and both chemical major ions and isotope analyses were conducted the data collected show that tds is strongly influenced by hco3 and cl and that a 3 component mixing process affects the groundwater s chemical composition the end members of this mixing process have been identified as a diluted hco3 meteoric water which enters the plain mainly from the eastern and northern sides of the study area b cl rich water which largely characterizes the shallow sandy horizons of the multilayered aquifer system and has been attributed to the presence of seawater as also suggested by 18o data and c so4 rich groundwater which is linked to the hot groundwater circulation within mesozoic carbonate formations and at first sight seemed to affect only the gravelly aquifer a so4 rich water also contributes to the sandy aquifer it probably enters the plain both laterally from the margins of the pisan mountains and from depth but promptly undergoes substantial so4 reduction processes by bacteria that such processes are at work is suggested both by the low so4 and high hco3 concentrations found in the well waters and by their c and s isotope compositions the collected data have allowed zones with higher quality waters to be identified which may someday be used for the local water supply

the use of na cl ratios to trace solute sources in a semiarid zone rainwater interaction with soils is a major source of dissolved salts in groundwater the transition zone between the humid and the arid area is characterized by a specific combination of reactions which do not exist elsewhere this combination of caco3 dissolution and base exchange reactions affects the na cl ratio which is the quantitatively most important parameter used for tracing salinity sources of groundwater the increase in the na cl ratio in the coastal plain aquifer of israel from north to south is related to local recharge of na rich water after interaction with soils of loessial origin

isotope study of moisture sources recharge areas and groundwater flow paths within the eastern batinah coastal plain sultanate of oman oxygen and hydrogen isotope analyses of rainfall samples collected on the eastern batinah coastal plain of northern oman between 1995 and 1998 indicate two different principal water vapor sources for precipitation in the area a northern mediterranean source and a southern indian ocean source as a result two new local meteoric water lines were defined for the study area isotopic analyses of groundwater samples from over 200 springs and wells indicate that the main source of water to the batinah coastal alluvial aquifer is high altitude rainfall from the adjacent jabal akhdar mountains originating from a combination of northern and southern moisture sources the groundwater recharged at high altitude forms two plumes of water which is depleted in the heavy isotopes 18o and 2h and stretches from the mountains across the coastal plain to the sea thereby retaining a chemical homogeneity horizontally and vertically down to a depth exceeding 300 m in contrast in areas adjacent to these two plumes the alluvial aquifer is geochemically stratified near the coast saline intrusion results in abrupt changes in chloride concentrations and isotope values

application of isotopic tracers as a tool for understanding hydrodynamic behavior of the highly exploited diass aquifer system senegal summary the diass horst aquifer system located 50 km east of dakar senegal is exploited in two main aquifers covered by a sandy superficial aquifer the confined unconfined palaeocene karstic limestone and the confined maastrichtian sandstone aquifer underneath this system has experienced intensive groundwater abstraction during the last 50 years to supply increasing water demand agricultural and industrial needs the high abstraction rate from 1989 to 2009 about 109 000 m 3 d has caused a continuous groundwater level decline up to 30 m a modification of the groundwater flow and salinization in parts of the aquifers the objective of the study is to improve our understanding of the system functioning with regards to high pumping identify the geochemical reactions that take place in the system infer origin and timing of recharge by using mainly stable 18 o 2 h 13 c and radioactive 3 h and 14 c isotopes water types defined in the piper diagram vary in order of abundance from ca hco 3 65 ca na cl 20 na hco 3 3 and na cl 12 values of 18 o and 2 h for the superficial aquifer range between 5 8 and 4 2 and between 42 and 31 respectively for the palaeocene aquifer they range from 5 8 to 5 0 and from 38 to 31 respectively values in the maastrichtian aquifer are between 5 9 and 4 3 for 18 o and 38 to 26 for 2 h plotted against the conventional 18 o vs 2 h diagram data from the upper aquifer exhibit a dispersed distribution with respect to isotopic fractionation while those of the palaeocene and maastrichtian aquifers are aligned parallel and slightly below or on the global meteoric water line gmwl evidencing ancient waters which had evaporated during infiltration the low tritium generally 14 c 0 7 57 2 pmc contents indicate predominance of older water being recharged during the pleistocene and holocene periods however few boreholes which exhibit high tritium 1 2 4 3 tu and 14 c 65 7 70 8 pmc values indicate some mixture with recent water likely through faulting and vertical drainage from the upper to deeper aquifers as well as lateral flow along flow paths to the piezometric depressions created by pumping

origin of recharge and salinity and their role on management issues of a large alluvial aquifer system in the semi arid haouz plain morocco the present study has analyzed the origin of recharge and groundwater salinity in the haouz alluvial plain located in central morocco stable isotopic data 18o 2h indicate that the recharge of the alluvial aquifer is dominated by high altitude meteoric water originating from the high atlas mountains that border the plain to the south tritium globally indicates the presence of recent groundwater as well as mixing between old and recent groundwater alluvial groundwater salinity varies from east to west this variability is mainly induced by enrichment in chloride and sulfate salt contents strontium content reveals that sulfate could be related respectively to the influence of the senonian carbonate deposits containing gypsum dissolution of halite is revealed by the plot of 18o vs cl where the most saline samples do not show any changes in 18o br cl ratio varies in a wide range probably due to an orographic effect the nitrate distribution was analyzed using indicator geostatistical techniques resulting in probability maps nitrate contamination is shown to occur particularly in the eastern part of the haouz plain in this paper some aspects of groundwater resources management are addressed different management actions are identified with regard to the current water resources status and to the land and water uses in this framework controlling groundwater abstraction optimizing irrigation and enhancing mountain front recharge constitute the major key management actions that should be carried out

quaternary marine ingressions as indicated by hydrogeochemical evidence in the semi confined aquifer of the littoral of the rio de la plata argentina the quaternary is characterized by the occurrence of significant climate oscillations that led to noticeable sea level changes on the basis of hydrochemical indicators the origin of the water salinity in the semi confined aquifer in the region of the middle rio de la plata estuary argentina is determined exploration wells were drilled and sediments were sampled for mineralogical analysis alongside water samples collected to determine major and minor ions and environmental isotopes in the aquifer the plio pleistocene fluvial sands in which the aquifer occurs are mainly composed of grains of quartz feldspar and mafic minerals the water chemistry shows na cl facies with a marked increase in salinity towards the rio de la plata the 18 o vs 2 h br vs cl and 18 o vs cl ratios clearly trend towards seawater minor ions such as si sr li se br and rb were the result of the prolonged interaction between the water that occurs in the aquifer and the mineral components of its matrix the hydrogeochemical data show the marine origin of the saline water and that the hydrogeological evolution of the area during the quaternary is as a result of sea level oscillations