tertiary extensional faulting and evolving ductile brittle transition zones in the northern snake range and vicinity new insights from seismic data new geologic mapping and high resolution seismic data from east central nevada shed light on the evolution of the northern snake range decollement nsrd and its relation to the present basins and ranges we suggest that the nsrd originated in oligocene time as a flat 20 km wide 7 km deep zone of decoupling between localized ductile stretching below and more widely distributed high angle normal faulting above younger east dipping normal faults cut the western part of the nsrd forming the tilted fault blocks and highly asymmetric grabens that constitute the duck creek range duck creek valley and schell creek range spring valley and folded the nsrd to its present antiformal geometry these youngest faults flatten into pervasive subhorizontal reflectors at a depth of 10 to 15 km that we interpret as the youngest ductile brittle transition

sulfur isotopes and hydrochemical variations in spring waters of southern indiana u s a abstract water chemistry and 34 s so 4 studies suggest two flow systems in the karst terrane of southern indiana 1 a shallow flow system exists which is dominated by surface water entering the ground through fractures and 2 a deeper regional groundwater flow system recharged by diffuse flow the chemistry of the water in the regional system may be dominated by the solution of gypsum in the lower st louis limestone sulfur isotope studies suggest two flow systems and show that the high so 2 4 concentrations in local waters result from solution of gypsum reported 34 s so 4 for upper mississippian evaporites and fresh water range from 14 to 19 to 8 to 12 respectively isotope analysis of gypsum cores from the lower st louis limestone evaporite unit shows 34 s values between 14 10 and 15 13 in the study area groundwater chemistry studies show a direct linear relationship between so 2 4 concentrations and 34 s values groundwater varies in so 2 4 concentrations between 20 and 1970 mg l 1 the 34 s values range from 10 61 for a conduit spring to 18 57 for a diffuse spring the waters with high so 2 4 concentrations have 34 s so 4 values higher than the local gypsum deposits analysed and contain h 2 s suggesting a deeper flow system in which fractionation by bacterial reduction of so 2 4 is occurring waters with low so 2 4 concentrations have 34 s so 4 values in the range of local fresh water indicating a shallow flow system

genesis and evolution of hco3 rich and so4 rich groundwaters of quaternary sediments pinawa canada abstract groundwaters collected from sediments at aecl research whiteshell laboratories include ca mg na hco3 na mg ca hco3 and ca mg na so4 hco3 water types the type produced is determined by the reactive phases encountered during migration through the enclosing sediments these include calcite gypsum and a clay substrate on which cation exchange occurs co2 charged soil waters undergo cation exchange reactions with solids of the enclosing sediments and dissolve calcite to saturation yielding ca mg hco3 groundwaters containing up to 700 mg l 1 total dissolved solids tds more saline sulphate rich groundwaters 1100 3000 mg l 1 tds are produced through combined reaction with gypsum calcite and a mg rich exchange substrate the type of groundwater produced is critically dependent upon the proportions of exchangeable cations on the bulk exchange substrate dissolution of gypsum increases so4 of the solutions but much of the released ca is taken onto the exchange substrate displacing na k first then mg continued gypsum dissolution causes precipitation of calcite and a decrease in solution ph the resulting saline waters are enriched in mg and na relative to ca compared with most groundwaters and are enriched in so4 relative to hco3 many sulphate rich groundwaters common to the northern north american prairies may have similar origins three solid phases exchange substrate calcite and gypsum are needed to model successfully these waters but interactions among them are complex calcite for example dissolves initially but is subsequently precipitated during evolution of sulphate rich waters consequently changes to major dissolved constituents and carbon isotopic ratios are difficult to predict without a comprehensive understanding of the geochemical evolution of these waters

soil moisture and groundwater responses to snowmelt on a drumlin sideslope abstract hillslope soil moisture and groundwater fluxes at a site in south central ontario were examined during the 1986 spring snowmelt near surface soil moisture was found to respond rapidly to the daily snowmelt cycle and a perched aquifer was formed in the latter stages of melt due to a progressive decrease in soil permeability with depth the delay between the initiation of snowmelt and the production of an extensive perched aquifer appears to have resulted from microscale variations in wetting behaviour induced by heterogeneity in soil texture and porosity subsequent additions of rainwater to the aquifer s capillary fringe produced an upward extension of phreatic conditions into more permeable near surface layers resulting in increased groundwater contributions from the hillslope previous studies indicate that saturation overland flow dominates the runoff response of catchments in this region during snowmelt the present results suggest that much of the return flow component of this runoff mechanism is produced by these transient perched aquifers this has implications for both hydrochemical studies and the use of environmental isotopes in investigations of snowmelt runoff

iron oxide copper gold iocg deposits through earth history implications for origin lithospheric setting and distinction from other epigenetic iron oxide deposits the iron oxide copper gold iocg group of deposits initially defined following discovery of the giant olympic dam cu u au deposit has progressively become too embracing when associated deposits and potential end members or analogs are included the broader group includes several low ti iron oxide associated deposits that include iron oxide p rich iron oxide f and ree rich fe or cu au skarn high grade iron oxide hosted au cu carbonatite hosted cu ree and f rich and iocg sensu stricto deposits consideration of this broad group as a whole obscures the critical features of the iocg sensu stricto deposits such as their temporal distribution and tectonic environment thus leading to difficulties in developing a robust exploration model the iocg sensu stricto deposits are magmatic hydrothermal deposits that contain economic cu and au grades are structurally controlled commonly contain significant volumes of breccia are commonly associated with presulfide sodic or sodic calcic alteration have alteration and or brecciation zones on a large commonly regional scale relative to economic mineralization have abundant low ti iron oxides and or iron silicates intimately associated with but generally paragenetically older than fe cu sulfides have lree enrichment and low s sulfides lack of abundant pyrite lack widespread quartz veins or silicification and show a clear temporal but not close spatial relationship to major magmatic intrusions these intrusions where identified are commonly alkaline to subalkaline mixed mafic even ultramafic to felsic in composition with evidence for mantle derivation of at least the mafic end members of the suite the giant size of many of the deposits and surrounding alteration zones the highly saline ore fluids and the available stable and radiogenic isotope data indicate release of deep volatile rich magmatic fluids through devolatization of causative mantle derived magmas and variable degrees of mixing of these magmatic fluids with other crustal fluids along regional scale fluid flow paths precambrian deposits are the dominant members of the iocg group in terms of both copper and gold resources the 12 iocg deposits with 100 tonnes t resources are located in intracratonic settings within about 100 km of the margins of archean or paleoproterozoic cratons or other lithospheric boundaries and formed 100 to 200 m y after supercontinent assembly their tectonic setting at formation was most likely anorogenic with magmatism and associated hydrothermal activity driven by mantle underplating and or plumes limited amounts of partial melting of volatile rich and possibly metal enriched metasomatized early precambrian subcontinental lithospheric mantle sclm fertilized during earlier subduction probably produced basic to ultrabasic magmas that melted overlying continental crust and mixed with resultant felsic melts with devolatilization and some penecontemporaneous incorporation of other lower to middle crustal fluids to produce the iocg deposits preservation of near surface deposits such as olympic dam is probably due to their formation above buoyant and refractory sclm which resisted delamination and associated uplift most precambrian iron oxide p rich or magnetite apatite kiruna type deposits have a different temporal distribution apparently forming in convergent margin settings prior to or following supercontinent assembly it is only in the phanerozoic that iocg and magnetite apatite deposits are roughly penecontemporaneous in convergent margin settings the phanerozoic iocg deposits such as candelaria chile occur in anomalous extensional to transtensional zones in the coastal cordillera which are also the sites of mantle derived mafic to felsic intrusions that are anomalous in an andean context this implies that special conditions possibly detached slabs of metasomatized sclm may be required in convergent margin settings to generate world class iocg deposits it is likely that formation of giant iocg deposits was mainly a precambrian phenomenon related to the extensive mantle underplating that impacted on buoyant metasomatized sclm generally smaller and rarer phanerozoic iocg deposits formed in tectonic settings where conditions similar to those in the precambrian were replicated

geological characteristics and metallogenesis of iron deposits in western tianshan china abstract the western tianshan metallogenic belt is one of the most significant polymetallic iron metallogenic belts in china important advances have been achieved recently in iron exploration in the awulale mountain in western tianshan china these newly discovered iron deposits are mainly hosted in the basic medium andesitic lavas and volcaniclastics often comprising a number of high grade ores magnetite is predominated in ore mineral assemblages and pyrite chalcopyrite pyrrhotite or sphalerite increase in certain deposits wallrock alterations are intensively developed exemplified as sodic calcic and potassic alterations which display in different patterns as country rocks and ore controlled structures vary skarn assemblages are commonly developed in ore districts like beizhan dunde and chagangnuoer and pyroxene albite k feldspar epidote actinolite alterations are dominated around ore bodies in zhibo deposit whereas the shikebutai deposit develops alteration assemblages comprising of jasper barite sericite and chlorite thus iron deposits can be divided into three types including volcanic sedimentary type volcanic magmatic hydrothermal type and iron skarn type our preliminary interpretation about the tectonic background of this iron mineralization in this area is in the late stage of a collisional accretional orogenic belt around carboniferous with some extrusional extensional tectonic transition locally iron mineralization is likely to have a close genetic relationship with volcanic subvolcanic activity syn or slightly post the volcanism which took place besides continental arc volcanic eruption contributes to majority of mineralizing iron with minor extracted from hydrothermal replacement from wall rocks

reconstruction of historical sea surface temperatures using empirical orthogonal functions abstract studies of climate variability often rely on high quality sea surface temperature sst anomalies although the high resolution national centers for environmental prediction formerly the national meteorological center optimum interpolation oi sst analysis is satisfactory for these studies the oi resolution cannot be maintained before november 1931 due to the lack of satellite data longer periods of ssts have come from traditional analyses of in situ ship and buoy sst observations alone a new interpolation method is developed using spatial patterns from empirical orthogonal functions e0fs that is a principal component analysis to improve analyses of sst anomalies from 1950 to 1981 the method uses the more accurate oi analyses from 1982 to 1993 to produce the spatial eofs the dominant eof modes which correspond to the largest variance are used as basis functions and are fit in a least squares sense to the in situ data to determine the time dependence of each mode a complete field

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

conceptual hydrogeological model of flow and transport of dissolved organic carbon in a small jura karst system summary this paper aims at characterizing infiltration and solute transport processes in a karst system during flood events in order to build a conceptual model of hydrogeological functioning the study site is the small karst system of fertans in the french jura soil cover rock matrix and a small spring were monitored to measure hydrological and hydrochemical parameters and particularly a continuous dissolved organic carbon doc signal which is a relevant environmental tracer of fast infiltration we used two combined approaches first from hydrodynamic and hydrochemical data we identified the system structure consistent with a dual porosity scheme and characterized the main processes occurring during flood events second on the basis of this scheme we built a new conceptual hydrogeological model coupled with doc transport to numerically validate the hydrological functioning this modelling approach is based on a rainfall discharge model to simulate spring flow solute transport is modelled using mixing equations including an empirical retardation factor as well as a first order solute decay the model was calibrated and validated on a set of nineteen flood events showing its performances in simulating spring hydrographs and delayed doc signals during flood events with various rainfall intensities we showed that the recharge area of the karst system varied largely with low and high groundwater periods which was attributed to the state of hydraulic connectivity in the unsaturated zone the soil cover appeared to play an important role of mixing and transfer for the recharge water the model simulated the contributions of pre event and event waters during flood events and allowed a better quantification of the available resource it showed in particular that total discharge of some flood events during low water periods is mainly composed of pre event water via piston flow type processes finally this study shows that the mixing model can simulate solute transport correctly taking into account degradation and retardation processes it highlights the need for a quantitative approach on hydrochemical studies of karst systems in order to understand them better

parsimonious recharge discharge modeling in carbonate fractured aquifers the groundwater flow in the gran sasso aquifer central italy summary in the carbonate fractured aquifer of the gran sasso central italy numerical simulations have been applied to validate a conceptual model of the recharge discharge cycle at regional scale to identify the effective aquifer features that mostly affect the spring discharges simple parsimonious models based on few key parameters whose effective values are well constrained by previous hydrological geological studies are used input data are represented by infiltration calculated considering rainfall snowmelt and runoff in endorheic basins and effective permeability distribution estimated by geological tectonic and hydrogeological settings of the aquifer discharges of tapped springs and tunnel drainages for the 1999 2009 period have been simulated after estimating the recharge area of each monitored spring by the hydrogeological setting and checking them by mean isotope elevation values discharge monitoring has been compared with the simulations obtaining a good agreement both at seasonal and yearly time basis the simulations will also be useful for previewing discharge in drought period and evaluating protection zones of tapped springs in the territory of a national park

the role of the subcutaneous zone in karst hydrology abstract the subcutaneous zone is the upper weathered layer of rock beneath the soil but above the permanently saturated phreatic zone it is of particular hydrological importance in karst because of its high secondary permeability arising from the considerable chemical solution in this zone however corrosional enlargement of fissures diminishes with depth thus permeability decreases in the same direction with the result that percolation is inhibited except down widened master joints and faults storage of water consequently occurs in this zone particularly after storms the upper surface of this suspended saturated layer in the subcutaneous zone is defined by a perched water table which slopes towards points of rapid vertical percolation the potential induces lateral water movement converging on the most permeable areas such as beneath dolines leakage from the subcutaneous store sustains slow percolation in the vadose zone cross correlation of rainfall with percolation rates in caves in new mexico u s a and new zealand reveal response lags of 2 14 weeks with no apparent relationship to depth below the surface other percolation sites show no correlation with rainfall interpreted as being a consequence of considerable friction in tight fissure networks the recognition of storage and rapid as well as very slow percolation from the subcutaneous zone requires re interpretation of the components of hydrographs from karst springs and of some conceptual models of karst aquifers the importance of subcutaneous storage in sustaining baseflow discharge at some sites must be recognised as must the contribution of subcutaneous water to flood hydrographs methods of estimating the volumes of subcutaneous and phreatic components of karst spring flood hydrographs are presented the paper concludes with a discussion of the significance of subcutaneous hydrologic processes for an understanding of karst geomorphology the desirability of explaining karst landform evolution in terms of hydrologic processes is stressed

geology geochemistry and geochronology of fe oxide cu au mineralization associated with şamli pluton western turkey abstract the amli balikesir fe oxide cu au deposit one of several iron cu au deposits in western turkey is hosted by porphyritic rocks of the multi phase amli pluton and metapelitic metadiabasic rocks of karakaya complex two successive mineralization events are recognized in the area as i early magnetite and sulfide and ii late hematite goethite native copper au alteration associated with the mineralization in amli is characterized by four distinct mineralogical assemblages they are in chronological order of formation 1 plagioclase early pyroxene scapolite 2 garnet late pyroxene 3 chlorite epidote and 4 chalcedony calcite alteration geochemical isotopic sr nd o s and geochronological ar ar data from alteration and magmatic rocks suggest a temporal and genetic link between the multiphase amli pluton and the hydrothermal system that controls the fe oxide cu au mineralization 40 ar 39 ar geochronology on hornblende and biotite separates of the amli pluton yielded an age range between 23 20 0 50 and 22 42 0 11 ma overlapping with 40 ar 39 ar age of 22 34 0 59 ma from alteration the close spatial and temporal associations of amli mineralization with porphyritic intrusions pervasive ca rich alteration calcic plagioclase andraditic garnet diopsidic pyroxene scapolite and epidote are considered as common features akin to calcic assemblages in typical iocg deposits besides abundant low ti 0 5 magnetite hematite high cu moderate au up to 8 82 ppm association structural control and lithologic controls of mineralization low s sulfide content chalcopyrite pyrite in the deposit and the derivation of causative magma from subduction modified subcontinental lithospheric mantle under a transpressional to transtensional regime are collectively considered as the features in favor of iocg type mineralization for the amli deposit

anomalous behaviour of specific electrical conductivity at a karst spring induced by variable catchment boundaries the case of the podstenjsek spring slovenia anomalous behaviour of specific electrical conductivity sec was observed at a karst spring in slovenia during 26 high flow events in an 18 month monitoring period a conceptual model explaining this anomalous sec variability is presented and reproduced by numerical modelling and the practical relevance for source protection zoning is discussed after storm rainfall discharge increases rapidly which is typical for karst springs sec displays a first maximum during the rising limb of the spring hydrograph followed by a minimum indicating the arrival of freshly infiltrated water often confirmed by increased levels of total organic carbon toc the anomalous behaviour starts after this sec minimum when sec rises again and remains elevated during the entire high flow period typically 20 40 s cm above the baseflow value this is explained by variable catchment boundaries when the water level in the aquifer rises the catchment expands incorporating zones of groundwater with higher sec caused by higher unsaturated zone thickness and subtle lithologic changes this conceptual model has been checked by numerical investigations a generalized finite difference model including high conductivity cells representing the conduit network discrete continuum approach was set up to simulate the observed behaviour of the karst system the model reproduces the shifting groundwater divide and the nearly simultaneous increase of discharge and sec during high flow periods the observed behaviour is relevant for groundwater source protection zoning which requires reliable delineation of catchment areas anomalous behaviour of sec can point to variable catchment boundaries that can be checked by tracer tests during different hydrologic conditions copyright 2011 john wiley sons ltd

contributions of c3 c4 organic materials and carbonate rock to dissolved inorganic carbon in a karst groundwater system on miyakojima island southwestern japan summary groundwater 13 c values and chemical compositions were employed to quantitatively evaluate the controlling processes and sources of dissolved inorganic carbon in a karst aquifer system on miyakojima island mi southwestern japan most mi groundwater is ca hco 3 type water but some na cl ca cl or na hco 3 type groundwaters occur formed mainly by seawater intrusion and partly by cation exchange reactions calculations using the wateq4f and phreeqc programs revealed that all mi groundwater not just the ca hco 3 type was strongly influenced by calcite dissolution in a karst aquifer system open with respect to soil co 2 initially derived from organic materials with mainly around 10 50 matm as pco 2 and that most groundwater was saturated with respect to calcite moreover oxidation of ammonium sulfate applied as fertilizer added h to the mi groundwater resulting in surplus calcite dissolution these processes sufficiently explained contents of alkalinity dic and ca 2 in the groundwater and were evaluated by model calculation using the phreeqc program with measured groundwater 13 c and ph values the results showed that the average mass fractions of dissolved inorganic carbon dic initially from calcite dissolution and c3 and c4 organic materials in the groundwater were 46 4 18 5 and 35 1 respectively the model results regarding the origins of dic in the groundwater agreed fairly well with land use distributions on mi in particular with the spatial distribution of forest and sugarcane fields and gave us some constrains of groundwater recharge areas and flowpaths

modeling of groundwater processes in a karstic aquifer of sierra madre oriental mexico abstract the sierra madre oriental smo is composed of ranges with important regional geological structures in highly fractured carbonate rocks abra formation which facilitate the recharge of aquifers at the regional scale recharge occurs in the western smo and locally in ranges such as palmillas la colmena and abra while the regional discharge is to the east in the huasteca zone intermountain valleys such as el salto are located near the regional discharge zone three end members were identified in these regions one related to local flow another to intermediate and a third to regional flow these flows define ternary mixing processes in groundwater in this paper the evolution of groundwater is studied which is important for learning the system performance and hydrogeochemical processes through vishmod virtual samples in hydrochemical modeling methodology the mixing model for the intermountain valleys indicates that many recharges occur for which local flow contributes 68 3 intermediate flow 12 3 and regional flow 19 4 the inverse modeling shows that the water rock interaction precipitation and or dissolution of calcite gypsum and dolomite are the main processes occurring in the aquifer system of the intermountain valleys

identifying water sources in a karst aquifer using thermal signatures using thermal data a unique approach to delineate flow components in a karsts aquifer was conducted thermal signatures from seven wells and six springs were analyzed to determine potential relationships among different storage reservoirs and the air temperature the temperature signatures revealed three distinct reservoirs epikarst shallow groundwater and deep groundwater the reservoirs have different thermal signatures and relationships with the air temperature during a wetter period the epikarst water temperatures more closely follow the air temperature trend and are closer in value but during drier conditions the shallow groundwater temperatures are more similar in value to air temperature deep groundwater temperatures show no relationship to variations in surface air temperature using the water temperatures from the three reservoirs the sources of water at two major springs copperhead and langle were delineated during the wetter period the shallow groundwater and the epikarst were the primary contributors of water to the springs as conditions became drier a transition occurred the deep groundwater became the major source of water to the springs variation in temperatures of waters at copperhead and langle spring is a result of the epikarst and the shallow groundwater which represents ineffective thermal reservoirs

influence of pyroclastic soil on epikarst formation a test study in southern italy terra nova 00 1 6 2010 abstract epikarst formation in the southern apennines italy was hypothesized to be significantly influenced by diffuse rainwater infiltration through soil of pyroclastic origin multidisciplinary investigations were carried out at an experimental field site to test this hypothesis at this site other factors influencing epikarst formation can be assumed invariant a direct relationship was observed between soil thickness and epikarst thickness this relationship supports the hypothesis that the pyroclastic soil plays a significant role in governing epikarst evolution and thickening the sandy loam texture and the high hydraulic conductivity of the soil allow easy rainwater infiltration therefore causing a diffuse interaction between percolation water and the soil medium and spatially homogeneous recharge within the aquifer system the soil contains a large accumulation of organic carbon and considerable co2 production results from the activity of autochthonous microorganisms belonging to different genera

seasonal fluctuation in δ15n of groundwater nitrate in a mantled karst aquifer due to macropore transport of fertilizer derived nitrate twenty wells were sampled and analyzed for nitrate content and nitrogen isotopes during late september 1986 the groundwater nitrate 15n values ranged from 6 8 to 17 6 with a mean of 10 3 eleven samples had 15n values greater than 9 5 indicating an animal waste origin septic tanks are probably the predominant source of waste derived nitrate macropores draining septic tank filter fields may provide a nearly continuous flow of effluent to the aquifer the 15n values of the other nine samples ranged from 6 8 to 8 4 suggesting a possible mixing of waste derived nitrate and that derived from isotopically lighter cultivation sources i e inorganic fertilizer and or mineralized soil organic nitrogen the twenty wells were resampled during late may 1987 shortly after inorganic fertilizers had been applied to the corpland throughout the study area the groundwater nitrate 15n values ranged from 3 6 to 14 7 with a mean of 8 3 nineteen of the wells showed a shift towards the lighter 15n values expected from the fertilizer derived nitrate the 15n decreases ranged from 0 6 to 4 8 with a mean of 2 2 despite the apparent influx of fertilizer derived nitrate eleven samples with 15n 8 0 to 14 7 still were composed of predominantly waste derived nitrate only nine samples with 15n 3 0 to 5 8 may have had fertilizer derived component approaching in magnitude that of waste derived nitrate regional groundwater nitrate concentration did not substantially increase macropore cracks root channels etc flow appears to contribute significantly to the recharge of the aquifer rapid response of the groundwater nitrate 15n values to fertilization demonstrates the ability of macropore flow to transport fertilizer derived nitrate which has been flushed from the tilled soil layer other agriculture chemicals pesticides and herbicides may also be transported to the aquifer in this manner

geochemical and statistical evidence of recharge mixing and controls on spring discharge in an eogenetic karst aquifer summary information about sources of recharge distributions of flow paths and the extent of water rock reactions in karst aquifers commonly result from monitoring spring chemistry and discharge to investigate the relationship between spring characteristics and the complexities of karst aquifers we couple variations in surface and groundwater chemistry to physical conditions including river stage precipitation and evapotranspiration et within a sink rise system through a 6 km portion of the upper floridan aquifer ufa in north central florida principal component analysis pca of time series major element compositions suggests that at least three sources of water affect spring discharge including allogenic recharge into a swallet diffuse recharge through a thin vadose zone and water upwelling from deep within the aquifer the deep water source exerts the strongest influence on water chemistry by providing a majority of na mg2 k cl and so 4 2 to the system anomalously high temperature at one of several monitoring wells reflects vertical flow of about 1 m year mass balance calculations suggest diffuse recharge and deep water upwelling can provide up to 50 of the spring discharge however their contributions depend on head gradients between the conduit and surrounding aquifer matrix which are influenced by variations in precipitation et and river stage our results indicate that upwelling from deep flow paths may provide significant contributions of water to spring discharge and that monitoring only springs limits interpretations of karst systems by masking critical components of the aquifer such as water sources and flow paths these results also suggest the matrix in eogenetic aquifers is a major pathway for flow even in a system dominated by conduits

the nitrogen isotope composition of groundwater nitrates from the east midlands triassic sandstone aquifer england abstract the 15 n 14 n composition of nitrates dissolved in groundwaters from 23 abstraction sites in the east midlands sherwood sandstone are reported dissolved n 2 ar ratios are with two exceptions consistent with atmospheric input and show that denitrification does not occur throughout most of the aquifer the nitrogen isotope composition of nitrates dissolved in the groundwaters can be shown not to have been mixed or fractionated to any significant extent within the aquifer the observed 15n no3 isotopic variations are attributed to four nitrate sources all of which are associated with agricultural land use

palaeogeographical relationships between alpine and jura glaciers during the two last pleistocene glaciations abstract two main moraine complexes are usually defined in the northwestern alpine piedmont the external moraine complex emc dated to the penultimate glaciation riss sensu lato and the internal moraine complex imc dated to the last glaciation wurm until recently the prevalent concept was that these two complexes had been built by glaciers originating in the central alpine zone this paper presents a new palaeogeographical diagram based on mapping and petrographical studies of these two moraine complexes and especially on the relationships between alpine and jura tills we reach the following conclusions 1 1 the jura glaciers were independent of the alpine glaciers during the two last pleistocene glaciations 2 2 the jura mountains formed a topographical barrier blocking and modifying the alpine glacier advance towards the northwest with the result that during the wurmian glaciation the maximum elevation 1200 m a s l of the alpine glaciers on the eastern margin of the jura was too low to allow alpine ice to enter the jura and during the rissian glaciation the greater thickness of the alpine glaciers resulted in their penetration only into the lower marginal zone of the jura 3 3 thus in the studied area the central alps were not the only centre of ice dispersal during the two last pleistocene glaciations on the northwestern jura slopes the corresponding moraine complexes were mainly built by glaciers emanating from the central jura

structural setting of the candelaria fe oxide cu au deposit chilean andes 27 30 s the candelaria fe oxide cu au ore deposit lies within the thermal aureole of the lower cretaceous magmatic arc plutonic suite in the candelaria punta del cobre district atacama region northern chile 27 30 s economic mineralization is present within a synplutonic ductile shear zone candelaria shear zone containing foliated and potassically altered volcanic and volcaniclastic rocks of the punta del cobre formation in the candelaria shear zone there was a complex interplay in space and time between ductile and brittle deformation during mineralization at high structural levels brittle moderately to steeply dipping extensional faults curve downward into gently dipping ductilely deformed rocks in the shear zone textural and structural characteristics of the ore and the deformed rocks indicate that the dilation of the sulfide bearing vein systems occurred at the same time as ductile deformation and implies that ductile brittle cycling occurred in a cooling hydrothermal system in the thermal aureole of the arc plutonic rocks the la brea and the san gregorio plutonic complexes are exposed in the plutonic arc immediately adjacent to the candelaria orebody the intrusions are interpreted to be flat lying tabular bodies emplaced by roof uplift floor depression mechanisms during regional extensional deformation an 40 ar 39 ar age of 119 6 1 2 ma and five k ar ages between 123 and 117 ma were obtained for the la brea pluton and an 40 ar 39 ar age of 111 5 0 4 ma was obtained for the san gregorio plutonic complex 40 ar 39 ar ages of 111 0 1 4 and 110 7 1 6 ma obtained from syntectonic biotite from the candelaria shear zone are interpreted to be the age of the mineralization these are indistinguishable from the age of the san gregorio plutonic complex and therefore heat from this pluton could have promoted ductile deformation during emplacement of the orebody this result together with known isotopic similarities between candelaria ore and the plutonic rocks implies that the san gregorio plutonic complex was the most probable source of the mineralizing fluids at candelaria although the critical intrusive unit may not be exposed the ore deposit is located where a roof uplift fold in the side wall of the san gregorio plutonic complex provided a dilatational site which may have drawn hydrothermal fluids out of the adjacent fractionating magmas into a structural trap in the punta del cobre formation below the carbonate rocks of the chanarcillo group

characterizing snowmelt anomalies in hydrochemographs of a karst spring cumberland valley pennsylvania usa evidence for multiple recharge pathways conductivity water level air temperature and depth of snowpack were monitored during a 26 day melt period of 88 cm deep snowpack at a karst spring to characterize internal runoff and diffuse infiltration chloride from road salt provided a tracer and the snowpack a recharge source during the melt period the melt period was divided into phases based on air temperature and chemograph pattern for the first and third phases mean air temperatures were below freezing but above freezing during the second and fourth phases during the first phase when the temperature peaked above freezing conductivity typically spiked 10 50 s cm suggesting input of road salt from conduits when the snowpack continuously melted conductivity and water level trends were upward with smaller daily spikes in conductivity indicating infiltration from the dilute snowpack this pattern suggests that road salt input continued when snowmelt recharged through the epikarst but at lower concentrations than the conduit input refreezing of the snowpack and shallow subsurface for a brief period interrupted the recharge and there was no longer a sawtooth pattern of conductivity it is apparent that frozen conditions did not cease recharge because a dual recharge process was evident while dual recharge from internal runoff and diffuse infiltration occurred the portions varied because of changing melting rates observed patterns indicated internal runoff dominated during frozen periods because recharge water moved as overland flow across a frozen surface to focused pathways diffuse infiltration became available during warmer periods because subsurface thawing allowed the snowmelt to penetrate the epikarst results of snowmelt monitoring in spring discharge indicated the transient nature of karst recharge

carbon isotope fractionation between dissolved carbonate co32 and co2 g at 25 and 40 c abstract carbon isotope fractionations e hco 3 co 2 g and e co 3 co 2 g have been obtained in open system experiments at medium ph measured isotopic fractionations e between total dissolved carbonate tdc and co 2 g were 7 32 0 07 and 6 15 0 08 at 25 and 40 c respectively assuming e co 2 aq co 2 g 1 06 from vogel et al 19 5 and ion speciation in the solution calculated fractionations e hco 3 co 2 g are 8 21 at 25 c and 6 71 at 40 c at high ph measured isotopic fractionations between tdc and co 2 g were 8 30 0 09 and 6 69 0 15 at 25 and 40 c respectively considering ion speciations and the above fractionation e hco 3 co 2 g we derived e co 3 co 2 g as equal to 8 38 at 25 c and 6 67 at 40 c

snowmelt infiltration and storage within a karstic environment vers chez le brandt switzerland summary even though karstic aquifers are important freshwater resources and frequently occur in mountainous areas recharge processes related to snowmelt have received little attention thus far given the context of climate change where alterations to seasonal snow patterns are anticipated and the often strong coupling between recharge and discharge in karst aquifers this research area is of great importance therefore we investigated how snowmelt water transits through the vadose and phreatic zone of a karst aquifer this was accomplished by evaluating the relationships between meteorological data soil water content vadose zone flow in a cave 53 m below ground and aquifer discharge time series data indicate that the quantity and duration of meltwater input at the soil surface influences flow and storage within the soil and epikarst prolonged periods of snowmelt promote perched storage in surficial soils and encourage surficial lateral flow to preferential flow paths thus in karstic watersheds overlain by crystalline loess a typical pedologic and lithologic pairing in central europe and parts of north america soils can serve as the dominant mechanism impeding infiltration and promoting shallow lateral flow further hydrograph analysis of vadose zone flow and aquifer discharge suggests that storage associated with shallow soils is the dominant source of discharge at time scales of up to several weeks after melt events while phreatic storage becomes import during prolonged periods without input soils can moderate karst aquifer dynamics and play a more governing role on karst aquifer storage and discharge than previously credited overall this signifies that a fundamental understanding of soil structure and distribution is critical when assessing recharge to karstic aquifers particularly in cold regions

solute and isotopic geochemistry and ground water flow in the central wasatch range utah ground water flow systems in the rugged central wasatch range utah were investigated by solute and isotopic methods six types of ground water systems were identified on the basis of rock type and structure the systems are broadly grouped into four categories 1 granitic systems 2 non granitic systems a unconsolidated alluvial systems b consolidated sedimentary rock systems and c fault controlled systems 3 thermal systems 4 mine drainage systems these ground water systems have distinctive solute and isotopic chemistries based on an analysis of 3h and 14c data all of the ground waters have a component of post 1952 recharge water and most of the ground waters are composed almost entirely of post 1952 recharge water a few of the ground water systems contain some water which is hundreds to perhaps thousands of years old the 18o and 2h data plot on a local meteoric water line and none of the data exhibit a positive 18o shift the absence of a positive 18o shift suggests maximum aquifer temperatures are approximately 100 c granitic terrains are dominated by fracture controlled local ground water flow systems which respond rapidly to recharge events the granitic ground water systems have estimated maximum circulation depths of about 160 m below land surface all the alluvial most of the consolidated sedimentary bedrock and some of the fault controlled ground water systems are shallow circulating local flow systems with short travel times ground water circulation of most of the local flow systems is within 200 m of land surface and is bedding plane controlled some of the consolidated bedrock and many of the fault controlled ground water systems are of the intermediate type and have circulation depths to 500 m four thermal ground water systems have been identified the thermal systems are heated by the geothermal gradient and have not circulated deeper than 2 2 5 km the thermal systems are of the intermediate and regional type the solute chemistry of most of the non granitic ground waters may be attributed to the dissolution of carbonate minerals and minor amounts of gypsum contributions of external co2 g to some of the thermal systems from either metamorphic or silicate hydrolysis processes is suspected

using isotope fractionation of nitrate nitrogen and nitrate oxygen for evaluation of microbial denitrification in a sandy aquifer the nitrate input into the groundwater from forest and agricultural land in the fuhrberger feld catchment area is virtually completely degraded by microbial denitrification in the aquifer five multilevel groundwater sampling wells show characteristic depth functions of nitrate proving the denitrification process a series of 10 samples of arable land groundwater was taken from different depths at these multilevel wells and isotope ratios of 15n14n and 18o16o in the nitrate were measured the sampling was based on the two dimensional vertical plane groundwater flownet and on the knowledge of the landuse upgradient of the multilevel wells high nitrate concentrations are associated with low 15n and low 18o values and vice versa the 15n 18o ratio indicates a linear increase with a slope of 1 2 1 the microbial dentrification accords with a rayleigh process with calculated enrichment factors of e 15 9 for 15n and e 8 0 for 18o three samples taken from groundwater recharged under coniferous forest show deviating characteristics low nitrate concentrations with low 15n values 1 4 but very high 18o values 40 50 using the previously quantified enrichment factors for 15n and 18o an attempt was made to ascertain the significance of denitrification in specific depth sections at two other multilevel wells 7 samples in two cases quantitative assessments on the degree of nitrate concentration decrease owing to denitrification were possible however in other cases the specific nitrate isotope fractionation was masked by the variability of nitrate concentration and of nitrate isotope ratios in the corresponding groundwater recharge preventing definite interpretations

stable isotope geochemistry of sulfate in relation to hydrogeology in southern saskatchewan canada abstract isotope and chemical analyses were carried out on soil and water samples collected from testholes drilled into different stratigraphic layers at six locations in the assiniboia area southern saskatchewan to understand the origin and distribution of so 4 and sources of groundwater recharge the 34 s so 4 and 18 o so 4 values were mostly negative indicating oxidation of highly reduced sulfide in subsurface environments as the major source of so 4 in the soils and groundwaters however positive or near positive 34 s and 18 o values in some of the samples indicated that oxidation of sulfide with positive or near positive 34 s values or dissolution of a so 4 mineral such as evaporite gypsum may serve as alternate sources of s salt concentration and isotope compositions in the eastend sand were nearly uniform in comparison with till and shale layers total s content in the sediments varied from 0 7 to 3 2 g kg with greater accumulations in the till layer which were mostly 1 0 g kg the insoluble s fraction of the sediments was 4 s was the major form of s the 34 s and 18 o values of soluble so 4 and 18 o and d values of groundwaters provide supporting evidence of groundwater flow direction determined by other techniques the d and 18 o values of the groundwater samples varied between 131 and 119 and 15 2 to 11 4 respectively without any correlation with stratigraphy these data plot on a d vs 18 o line with a slope of 2 0 this departure from the meteoric water line with slope of 8 0 appears to be the result of evaporation or oxygen exchange with soil minerals the o isotope data suggest that exchange between so 4 and h 2 o is very slow under the conditions prevailing in the subsurface

sulfate in brines in the crystalline rocks of the canadian shield abstract deep groundwaters in crystalline rocks typically are very saline and are characterized by a rather unique ca na cl dominated chemistry sulfate is present in variable amounts and may be linked to both the geochemical evolution of these fluids as well as to recent processes initiated through mining activities it is possible to distinguish on the basis of isotopic compositions between brine sulfate and secondary sulfate formed by oxidation of sulfides the latter is characterized by 34 s values which reflect the local mineral sulfide precursor and 18 o close to or below 0 smow the isotopic composition of the brine sulfate is characterized by 18 o and 34 s values which resemble marine isotopic compositions at some localities at others they could be explained as being of magmatic hydrothermal origin it is likely that the sulfate participated in the geochemical evolution of these brines thus its isotopic composition reflects geochemical processes rather than a primary origin no evidence for the influence of bacterial reduction was found

contrasting tectonic settings and sulfur contents of magmas associated with cretaceous porphyry cu mo au and intrusion related iron oxide cu au deposits in northern chile porphyry cu mo au and iron oxide copper gold iocg deposits share many similarities e g fe cu and au contents but also have important differences e g the predominance of sulfide minerals in porphyry deposits and iron oxides in iocg deposits genetic comparisons are complicated by the broad definition of iocg deposits here we restrict our study to iocg deposits that are related to igneous intrusive systems in the mesozoic coastal cordillera of northern chile both porphyry and iocg deposits occur in close spatial and temporal proximity offering the chance to examine what controls their different modes of formation from detailed examination of the timing geochemistry and tectonic setting of associated igneous rocks based on new and published data we find that rocks associated with mid cretaceous iocg deposits 125 110 ma are largely indistinguishable from those associated with slightly earlier 125 ma and later 110 ma porphyry cu mo au deposits magmas related to iocg deposits were formed during a brief period of back arc transtension in the mid cretaceous and are on average somewhat more mafic dioritic locally alkaline and isotopically primitive compared to granodioritic magmas associated with porphyry deposits formed during normal contractional arc tectonics in the later cretaceous however these compositional ranges overlap and the differences are not clear enough to be diagnostic we measured the so3 content of igneous apatite from selected samples of these rocks to test the hypothesis that the difference in sulfur content of the ore deposits was due to differences in sulfur content of the associated magmas early igneous apatite crystals occurring as inclusions in silicate phenocrysts from the carmen de andacollo porphyry cu au deposit re os molybdenite ages of 103 9 0 5 ma 103 6 0 5 ma are significantly richer in s 0 25 0 17 wt so3 n 69 than similar apatite crystals from two iocg deposits candelaria casualidad and a sample of regional mid cretaceous igneous rock from near productora 0 04 0 02 wt so3 n 76 using published partition coefficients for s between apatite and oxidized silicate melt we semi quantitatively estimate corresponding magmatic sulfur contents of 0 02 wt s in the carmen de andacollo magmas versus 0 001 to 0 005 wt s in the iocg associated magmas this is an order of magnitude difference and the opposite of what would be expected if the difference were due to bulk magma composition sulfur solubility is generally higher in mafic magmas whereas here the s content is higher in the more felsic porphyries we conclude that the porphyry forming magmas indeed had higher s contents than the iocg related magmas and suggest that these differences reflect different petrogenetic processes during normal subduction magmas derived from the metasomatized mantle wedge are hydrous moderately oxidized and s rich and have the potential to generate s rich porphyry type deposits in contrast in back arc extensional settings upwelling asthenospheric melts carry a weaker subduction signature including lower s contents interaction of these s poor magmas with previously subduction modified upper plate lithosphere is more likely to give rise to s poor iocg deposits

soil and karst aquifer hydrological controls on the geochemical evolution of speleothem forming drip waters crag cave southwest ireland abstract in recent years there has been increased interest in cave speleothems as archives of palaeoclimate monitoring of rainfall and soil and karst water chemistries was performed at crag cave castleisland co kerry southwest ireland in august 1997 and january 1998 in order to understand temporal and spatial variations in karst water hydrology and chemistry and their implications for interpreting the potential palaeohydrological signal preserved by speleothems at this site temporal variations in karst water drip rates and geochemistry allow drips to be classified by hydrological response to rainfall and the associated processes of dilution piston flow source change and prior calcite precipitation during aquifer throughflow evolution from soil matrix and preferential flow solutions has also been determined to exert an important control on karst water chemistries as a result of these findings we present hydrogeochemical models and plumbing diagrams that delineate the controls on karst water evolution at a number of sampling locations within the cave at this site we propose that a palaeohydrological signal may be recorded by crag cave speleothems that may be interpreted via the study of mg ca ratios in speleothems linked to monitoring of modern drip water chemistry

temperature driven meltwater production and hydrochemical variations at a glaciated alpine karst aquifer implication for the atmospheric co2 sink under global warming about two hydrological years of continuous data of discharge temperature electrical conductivity and ph have been recorded at the glarey spring in the tsanfleuron glaciated karst area in the swiss alps to understand how glaciated karst aquifer systems respond hydrochemically to diurnal and seasonal recharge variations and how calcite dissolution by glacial meltwater contributes to the atmospheric co2 sink a thermodynamic model was used to link the continuous data to monthly water quality data allowing the calculation of co2 partial pressures and calcite saturation indexes the results show diurnal and seasonal hydrochemical variations controlled chiefly by air temperature the latter influencing karst aquifer recharge by ice and snowmelt karst process related atmospheric co2 sinks were more than four times higher in the melting season than those in the freezing season this finding has implication for understanding the atmospheric co2 sink in glaciated carbonate rock terrains the carbon sink will increase with increasing runoff caused by global warming i e carbonate weathering provides a negative feedback for anthropogenic co2 release however this is a transient regulation effect that is most efficient when glacial meltwater production is highest which in turn depends on the future climatic evolution

plutonism and the origin of metamorphic core complexes the formation of metamorphic core complexes may be triggered by plutonic activity during episodes of continental extension pulses of ductile deformation have taken place during short lived thermal events initiated by the heat input from intruded plutons sills or dikes such intrusions may be the underlying cause for differential uplift of the footwall during tectonic denudation of metamorphic core complexes fast cooling inferred from 40 ar 39 ar apparent ages may have taken place after periods of magma arrival and need not be the result of rapid erosional or tectonic denudation heterogeneity of 40 ar 39 ar apparent ages can be explained by rapid cooling of deforming mylonites formed at shallow crustal levels in the thermal aureoles of intruded sills or sill swarms under such circumstances apparently isothermal decompression paths may actually link pressure temperature points set during periods of transient mineral growth during and after periods of igneous activity

isotopic composition of precipitation in central iowa abstract the isotopes of hydrogen and oxygen have been used extensively as indicators of groundwater age 3h and paleotemperature of groundwater recharge 18o 16o 2h 1h however comparisons of values in groundwater with those in recent precipitation are few this study describes and interprets the isotopic composition of precipitation in central iowa for the year 1992 an unusually mild winter driven by south westerly flow of the jet stream was followed by an unusually cool and predominantly dry summer that was caused by a persistent northwesterly flow in the upper atmosphere temperature was below normal 9 0 c precipitation was above normal 868 4 mm and was mostly derived from a gulf of mexico moisture source fifty one precipitation samples were collected from 37 events and analyzed for hydrogen and oxygen isotopes tritium activities ranged from 0 to 44 tritium units tu and the weighted mean 3h activity was 11 02 tu a value consistent with international atomic energy agency iaea data anomalously high 3h activities suggested input of technogenic 3h weighted mean values of 18o and 2h were 8 02 and 53 62 respectively and the equation of the local meteoric water line was 2h 9 26 18o 4 65 weighted mean 18o and 2h values from the gulf pacific moisture source 10 80 74 82 were more depleted than those ascribed solely to a gulf of mexico moisture source 7 24 47 39 seasonal differences in temperature primarily controlled these differences in isotopic composition

lithological and structural controls on the genesis of the candelaria punta del cobre iron oxide copper gold district northern chile abstract the candelaria punta del cobre district is the largest iron oxide cu and au iocg district in the chilean iocg belt with more than 13 mt of contained copper candelaria is the most important deposit in the district which includes seven other smaller producers carola punta del cobre mantos de cobre candelaria norte granate alcaparrosa atacama kozan las pintadas the district which is characterized by an early cretaceous volcanic sedimentary arc sequence 135 132 ma punta del cobre formation overlain by the marine sedimentary chanarcillo group formed in an extensional back arc basin 132 130 ma the copiapo batholith which occupies the western side of the district was emplaced between 118 and 110 ma during the change from extensional to transpressional tectonics mineralization is hosted predominately in the upper part of the lower andesite member and the overlying volcano sedimentary and dacite members all within the punta del cobre formation mineralization is hosted by fault zones breccias and specific lithologies north northwest faults are the dominant host for vertically extensive orebodies stratigraphically controlled mineralization forms extensive stratabound ore bodies mantos textural evidence suggest that the hydrothermal system evolved and advanced upwards over time the earliest event was dominated by magnetite actinolite in stratigraphically controlled mantos and extensive zones of disseminated magnetite actinolite below candelaria which were subsequently overprinted by chalcopyrite dominant mineralization with magnetite actinolite biotite k feldspar alteration in addition to magnetite iron oxides include widespread mushketovite and hematite in the upper part of some deposits geochronological data suggest that the main phase of mineralization occurred between 122 ma and 115 ma u pb in zircon overlapping in age with the two major early phases of the copiapo batholith there is no field evidence to indicate that exposed phases of the batholith were the source of mineralizing fluids alteration and mineralization in the earliest phase of the batholith la brea occurs in structures and is minor compared to mineralization in the punta del cobre formation later phases of the batholith cut the main stage of mineralization the extent of iocg mineralization in the candelaria punta del cobre district reflects a combination of factors including changing regional kinematics and related fault architecture multiple intrusive events fluid access to permeable and reactive lithologies vertical changes in redox conditions and the potential role of multiple fluids

temperature as a marker for karstic waters hydrodynamics inferences from 1 year recording at la peyrere cave ariege france abstract we present temperature measurements recorded at a 15 min time step between october 2002 and april 2003 inside the la peyrere cave baget karstic system central pyrenees on six 0 01 c sensitivity sensors distributed on the whole recognized cave down to a depth of 57 m rainy events are associated to a steep signal of a few hundredth to a few tenth of degrees in amplitude starting 1 h to one day after rain and with a sign depending mostly of the outside temperature the temperature signal does not correlate well with the rainfall while the water level does with a maximum water rising rate 2 5 h after rain the spectral density of the temperature signal displays one peak at a period of 3 days which is also present in the rain signal and which is likely to be related to climatic parameters and a broad smooth zone of spectral energy close to a 1 day period by comparing a superficial and a deepest group of sensors we note that the flood signal is more pronounced on the deepest sensor group whatever the outside temperature and that the annual temperature variation is also larger on this sensor group this could indicate that rain water flows in the cave through its base and explain the development in depth of the cave due to the arrival of water with different temperatures and mineralizations at different levels double diffusive convection is likely to be triggered in the cave we suggest that the onset of convection could be associated to the oscillations observed on the temperature signal at the onset of the flood

modelling of the functioning of karst aquifers with a reservoir model application to fontaine de vaucluse south of france summary this work deals with a rainfall discharge model applied to a well known karst aquifer a new approach is developed in order to minimize the fitting parameters here some of the model parameters do not result from a simple fitting as it was the case with earlier models i e some of them were assessed from the hydrograph analysis the conceptual model of the functioning is based on a production function based on a simple calculation of effective rainfall and a transfer function consisting of two reservoirs a slow discharge reservoir transfers the low flow and a rapid discharge reservoir feeds the high flow the model has three fitted parameters plus one for its initialisation three parameters are deduced from the hydrograph analysis over the entire time series for example the recession coefficient of the slow discharge reservoir is determined from the hydrodynamic analysis of the recession mangin a 1975 contribution a l etude hydrodynamique des aquiferes karstiques 3eme partie constitution et fonctionnement des aquiferes karstiques annales de speleologie 30 1 210 124 this model was tested over a ten years period on the fontaine de vaucluse french karst system the first hydrological year is used for fitting the model the nine other cycles validate the modelling the good quality of the model is proved by the nash criterion of 92 3 on the validation period moreover the simulation results were validated by a statistical analysis of measured and simulated time series the model successfully simulates both the high and low flow at the same time also it estimates the water volumes available in the different parts of the aquifer and it proposes a management tool capable of predicting the evolution of the discharge in different climate conditions

how can the epikarst zone influence the karst aquifer hydraulic behaviour the role of an epikarst zone in the karst aquifer hydraulic behaviour was brought into focus in our studies referring to the catchment area of the hubelj spring sw slovenia this study points out the significance of effects of the fast preferential flow epiflow which is the main factor controlling solute contaminant transport towards the aquifer saturated zone the so called epikarstic hypothesis is verified on the basis of the most significant research results that are supported by the most important findings from the literature

bayesian modelling and ensemble reconstruction of mid scale spatial variability in north atlantic sea surface temperatures for 1850 2008 existing historical records of sea surface temperature extending back to the mid 1800s are a valuable source of information about climate variability on interannual and decadal time scales however the temporal and spatial irregularity of these data make them difficult to use in climate research where gridded and complete data fields are expected for both statistical analysis and forcing numerical models infilling methods based on constraining the solution to the linear space spanned by the leading eigenvectors of the global scale covariance otherwise known as reduced space methods have proven very successful in creating gridded estimates of sea surface temperature these methods are especially useful for infilling the vast regions of unobserved ocean typical of the earliest segments of the data record regional variability on the other hand is not well represented by these methods especially in data poor regions here we present a method for augmenting the established large scale reconstruction methods with a statistical model of the mid scale variability using high quality sea surface temperature data from the last 30 years including satellite derived records we specify a spatially non stationary anisotropic covariance model for the mid scale sea surface temperature variability with the parameters of the covariance model estimated from the modern record historical observations are used for conditioning the posterior distribution specifically we form the expected value and correlated uncertainty of the mid scales as well as generating samples from the posterior while this work focuses on a limited domain in the midlatitude north atlantic ocean the method employed here can be extended to global reconstructions copyright 2011 royal meteorological society

water movement in desert soil traced by hydrogen and oxygen isotopes chloride and chlorine 36 southern arizona abstract understanding soil water movement is important for water resource management and for analyzing pollutant transport in the vadose zone seasonal variations in shallow soil profiles may have profound effects on deep soil water and solutes we have investigated seasonal soil water movement in the top meter of undisturbed desert soil in the southern arizona using 2 h 18 o cl and bomb 36 c1 six soil profiles were sampled from a young terrace holocene during 1991 to 1992 on a seasonal basis one soil profile was sampled from an older terrace latest pleistocene in october 1992 and one from a yet older fan surface late pleistocene in march 1992 the results indicate that repeated seasonal cyclic movement of soil water in the top 60 80 cm active zone tends to produce a consistent stable isotope composition for the soil water below the active zone in different seasons the deep 18 o on the oldest surface is about 6 heavier than on the younger surfaces probably resulting from greater evaporative loss due to the larger proportion of fines in the older soil this deep isotopic composition is closely related to the composition of the local average annual precipitation an annual average evaporation rate of 35 mm year 1 was estimated using a steady state diffusion model whereas the actual regional evapotranspiration rate is 175 250 mm year 1 this suggests that about 80 of the soil water is lost through transpiration and first stage evaporation before quasi steady state is reached the long term average infiltration rate below the active zone is about 4 mm year 1 for the younger terrace based on both chloride mass balance and bomb 36 cl and 0 02 mm year 1 for the older terrace and the fan surface based on chloride mass balance the correlation between the deep 18 o the reduction of downward flux and the surface age suggests that increasing soil development has resulted in a significant decrease of soil water infiltration and hence an increase in evaporation and surface runoff

a four component mixing model for water in a karst terrain in south central indiana usa using solute concentration and stable isotopes as tracers the study area lies in a highly karstified carbonate terrain in south central indiana sinkholes conduits and caves form large secondary pathways for the subsurface flow as a result the discharge from a main emergence point for the subsurface flow system the orangeville rise quickly responds to the storm events and shows wide variations in flow rate water chemistry and stable isotopic compositions these responses are attributed to the mixing of water in secondary pathways in the study area recharge occurs through the thick mantled karst plain and the sinkhole plains and the role of soil layer and epikarst in the recharge process is of great importance rain dic 2 hco3 mg l 13cdic 7 soil water dic 544 hco3 mg l 13cdic 14 7 epikarstic water dic 224 hco3 mg l 13cdic 13 6 and phreatic diffuse flow water dic 299 hco3 mg l 13cdic 11 8 generally showed unique and constant dissolved inorganic carbon dic and 13cdic values over time using dic and 13cdic as tracers a four component mixing model was established for the karstic flow system by constructing the discharge hydrograph separation curves the mixing ratio of each component rain 10 6 soil 3 1 epikarstic 52 3 and phreatic 34 0 water was determined for the orangeville rise discharge over the testing period of 104 h after the storm event of 10 4 90 vadose water occupied 55 4 of spring discharge and this demonstrates the importance of the unsaturated zone especially the epikarst in the karstic flow systems

environmental tritium and 18o applied in a hydrological study of the wairau plain and its contributing mountain catchments marlborough new zealand abstract isotope data tritium and 18 o for rivers and ground water acquired since 1968 are combined with geological hydrological and hydrochemical evidence to determine sources and flow patterns of ground water in gravel aquifers of the wairau coastal plain and its southern tributary valleys determination of the components of groundwater origin depends on a strong west east gradient of 18 o concentration between mountain catchment precipitation feeding rivers flowing to the plain and rainwater falling directly on the plain the main aquifer is postglacial alluvial material deposited by wairau river deriving its water from that river locally infiltrated precipitation contributes at most only a few percent to the flow in the shallowest gravels downstream of the infiltration zone in the south of the plain the unconfined aquifer comprises material deposited during the last glaciation its ground water has both local precipitation and inflow from southern tributary streams as appreciable sources the main aquifer is confined near the coast where it is overlain by up to 60 m of marine sediments deposited during postglacial marine transgression and subsequent coastal progradation tritium concentrations show that ground water in the shallowest geological stratum rapaura gravels reaches the confined zone boundary less than 1 year after recharge from the river with much shallow flow being discharged at the surface just upstream of the boundary in contrast ground water in the underlying unit speargrass gravels requires at least 10 years to reach this point analysis of tritium concentrations in the confined zone shows a central zone through which the faster flowing rapaura component dominates as far as the coast but also areas to the north and south where ground water in the rapaura gravels has a dominant older component the combined evidence reveals that the confined ground water is leaking into the overlying sediments allowing water to flow from the lower speargrass gravels into the rapaura gravels because wairau river is the dominant source of ground water for the main aquifer its response to bomb tritium input to its mountain catchments is given detailed consideration much of the river water derives promptly from bare catchment areas but the analysis suggests that about 50 is retained for about 8 years on average before release to the river large deposits of scree in higher lying formerly glacial catchments appears to be the major factor in the surprisingly large quantity of stored water implied by this result

infiltration mechanisms related to agricultural waste transport through the soil mantle to karst aquifers of southern indiana usa abstract a hydrogeological study was conducted during the 1991 1992 water year in the clay soil mantled portion of a limestone terrain in southern indiana the purpose of the study was to investigate the modes of soil water infiltration contributing to rapid transport of nitrate to the saturated zone the 1 year cycle profiles of nitrate concentration vs time show a consistent increase of nitrate at various depths in the unsaturated zone during the period of investigation the increase of nitrate in soil water is attributed to the rapid flushing of the inorganic fertilizers from the fields after the area received sufficient rainfall in late fall the investigation also showed a major movement of nitrate in quick pulses through the unsaturated zone rather than a slow uniform recharge immediately after a major storm event the asymmetric profiles of nitrate concentration vs depth point to the existence of preferential flow through macropores in the clay soil mantle above the bedrock soil water transport between storm events is by matrix type flow nitrogen isotopes were analyzed for representative groundwater samples collected before and immediately after fertilization of fields in the summer 1991 the 615n values of the samples did not show any major shift in nitrate sources between the sampling periods the summer of 1991 was extremely dry prohibiting vertical transport of nitrate from the fields to the groundwater system any change in nitrate concentration in groundwater during this time is attributed to the mixing through lateral flow within the aquifer

geochemical and isotopic studies of groundwater conditions in the densu river basin of ghana the densu river basin drb is an important agricultural area in ghana and has a high population density water shortages have occurred in the basin due to drying out of surface water heavy pollution and low yield in most of the production wells which are crucial factors restricting sustainable socioeconomic development this study was carried out to investigate the geochemical characteristics and evolution as well as recharge processes in the drb system with regard to the tectonics geomorphology lithology and flow system it mainly used hydrochemistry environmental isotopes and a series of comprehensive data interpretation e g statistics ionic ratios and piper diagram to obtain a better understanding of the functioning of the system the following hydrochemical processes were identified as the main factors controlling the water quality of the groundwater system weathering of silicate minerals dissolution ion exchange and to a lesser extent evaporation which seems to be more pronounced downgradient of the flow system as groundwater flows from the recharge to discharge areas chemical patterns evolve in the order of ca2 hco3 ca2 mg2 hco3 to ca2 na cl ca2 na hco3 and na cl according to lithology the environmental isotope 18o 2h 3h measurements further revealed that groundwater in the drb was a relatively well mixed system as evidenced by the encoded narrow range of values however deviation from the rainwater signature indicates combined local processes such as direct percolation through preferential channels evaporation and probable surface water and anthropogenic contribution to the system

geochemistry of dissolved inorganic carbon and carbonate weathering in a small typical karstic catchment of southwest china isotopic and chemical constraints abstract the sources of dissolved inorganic carbon dic and rock weathering processes were studied in the houzhai catchment a typical karstic catchment in the changjiang river basin southwest china the carbon isotopic compositions 13 c dic of dic in the samples collected from the catchment vary from 13 5 to 6 9 with a mean value of 9 8 the dic in the catchment is thereby considered to be mainly derived from soil co 2 and weathering of carbonate rocks the dic concentrations and the 13 c dic values show pronounced seasonal variations with the lowest values being observed during the high flow season from may to october the logpco 2 values in the waters were positively correlated with the dic contents and negatively correlated to the saturation index of calcite sic and 13 c dic values these observations indicate that co 2 derived from organic matter oxidation plays an important role in the dissolution of carbonate for this typical karstic environment based on a chemical mass balance the weathering rate of carbonate rocks in the houzhai catchment was estimated to be approximately 133 t km 2 year or 584 10 3 mol km 2 year in terms of co 2 consumption rate which is higher than the reported values for other rivers in southwest china

identification of a karst system s intrinsic hydrodynamic parameters upscaling from single springs to the whole aquifer for water management purposes information about an entire aquifer system is generally more important than information about a specific spring since a karstic aquifer system might drain to several outlets conclusions derived from a single spring can be misleading for characterization and modeling in this study we apply a conceptual model to an alpine dolomite karst system in austria the particular challenge was that several small springs with strongly varying hydrological behavior and diffuse flow into surrounding streams drain this system instead of applying the model to a single spring it was calibrated simultaneously to several observations within the system aiming to identify the karst system s intrinsic hydrodynamic parameters parameter identification is supported by modeling the transport of water isotopes 18o the parameters were transferred to the whole system with a simple upscaling procedure and a sensitivity analysis was performed to unfold influence of isotopic information on parameter sensitivity and simulation uncertainty the results show that it is possible to identify system intrinsic parameters but the sensitivity analysis revealed that some are hardly identifiable only by considering uncertainty reasonable predictions can be provided for the whole system including isotopic information increases the sensitivity of some intrinsic parameters but it goes along with a sensitivity decrease for others however a possible reduction of prediction uncertainty by isotopic information is compensated by deficiencies in the transport modeling routines

detachment faulting and late paleozoic epithermal ag base metal mineralization in the spanish central system hydrothermal activity during late hercynian time resulted in epithermal silver base metal pb zn cu vein formation in the eastern part of the spanish central system during the hercynian orogeny the central iberian crust was thickened by compressional tectonics heated weakened and subsequently overthickened by massive late hercynian granitic intrusions subsequently the central iberian crustal welt underwent extensional collapse through lithosphere scale low angle detachment faulting the detachment systems evolved through tectonic denudation isostatic rebound and upward arching to define an extensional province much like the u s basin and range andesitic volcanism and hydrothermal activity occurred during extension inducing epithermal type hydrothermal convecting systems that leached transported and precipitated silver and base metals along fractures crosscutting the hiendelaencina metamorphic core complex

the candelaria cu fe au and punta del cobre cu fe deposits copiapo chile a case for extension related granitoid emplacement and mineralization processes the lower cretaceous volcanic formations of copiapo chile host major stratiform disseminated vein and stockwork mineral deposits among these are the punta del cobre district cu fe and the neighbouring large candelaria deposit cu fe au these deposits are likely to have formed during a major extensional event that was accompanied by granitoid emplacement that triggered important contact metamorphism metasomatic activity and mineralization processes we suggest here that alteration mineralization processes developed within the upper plate domain of a nne trending ese dipping extensional system while granitoids were accomodated within the lower plate if this model prove to be right candelaria type deposits may be hidden beneath the present higher structural position of the punta del cobre district

a tripole index for the interdecadal pacific oscillation a new index is developed for the interdecadal pacific oscillation termed the ipo tripole index tpi the ipo is associated with a distinct tripole pattern of sea surface temperature anomalies ssta with three large centres of action and variations on decadal timescales evident in the second principal component pc of low pass filtered global sst the new index is based on the difference between the ssta averaged over the central equatorial pacific and the average of the ssta in the northwest and southwest pacific the tpi is an easily calculated non pc based index for tracking decadal sst variability associated with the ipo the tpi time series bears a close resemblance to previously published pc based indices and has the advantages of being simpler to compute and more consistent with indices used to track the el nino southern oscillation enso such as nino 3 4 the tpi also provides a simple metric in physical units of c for evaluating decadal and interdecadal variability of sst fields in a straightforward manner and can be used to evaluate the skill of dynamical decadal prediction systems composites of sst and mean sea level pressure anomalies reveal that the ipo has maintained a broadly stable structure across the seven most recent positive and negative epochs that occurred during 1870 2013 the tpi is shown to be a robust and stable representation of the ipo phenomenon in instrumental records with relatively more variance in decadal than shorter timescales compared to nino 3 4 due to the explicit inclusion of off equatorial sst variability associated with the ipo