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

groundwater composition hydrochemical evolution and mass transfer in a regional detrital aquifer baza basin southern spain abstract the physical chemical characteristics of the groundwater in the baza caniles detrital aquifer system indicate that a wide diversity of hydrochemical conditions exists in this semiarid region defining geochemical zones with distinct groundwater types the least mineralized water is found closest to the main recharge zones and the salinity of the water increases significantly with depth towards the center of the basin geochemical reaction models have been constructed using water chemistry data along flow paths that characterize the different sectors of the aquifer system namely quaternary aquifer unconfined sector and shallow and deep confined sectors of the mio pliocene aquifer geochemical mass balance calculations indicate that the dominant groundwater reaction throughout the detrital system is dedolomitisation dolomite dissolution and calcite precipitation driven by gypsum dissolution this process is highly developed in the central part of the basin due to the abundance of evaporites apart from this process there are others which influence the geochemical zoning of the system in the quaternary aquifer which behaves as a system open to gases and which receives inputs of co 2 gas derived from the intensive farming in the area the interaction of the co 2 with the carbonate matrix of the aquifer produces an increase in the alkalinity of the water in the shallow confined sector of the mio pliocene aquifer the process of dedolomitisation evolves in a system closed to co 2 gas ca 2 na cation exchange and halite dissolution processes are locally important which gives rise to a relatively saline water finally in the deep confined sector a strongly reducing environment exists in which the presence of h 2 s and nh 4 in the highly mineralized groundwater can be detected in this geochemical zone the groundwater system is considered to be closed to co 2 gas proceeding from external sources but open to co 2 from oxidation of organic matter the geochemical modeling indicates that the chemical characteristics of this saline water are mainly due to so 4 dissolution dedolomitisation and so 4 reduction coupled with microbial degradation of lignite

geochemistry and geochemical modeling of unsaturated zone in a tropical region in urânia sao paulo state brazil summary the geochemistry of a thick unsaturated zone in a tropical region in ur nia sao paulo state brazil has been investigated the site was instrumented for pressure head measurements and pore water sampling above the water table at 9 5 m depth the composition of the solid phase was determined by x ray diffraction optical microscopy sem and microprobe and icp aes analyses of decomposed samples the unsaturated zone is composed mainly of clayey sand and can be subdivided into three zones a shallow zone down to depth of 2 m corresponding to the evaporation line an intermediate zone between 2 and 7 m where small wetting fronts dissipate and only longer recharge events are evidenced by changes of pressure head and a deep zone between 7 and 9 5 m where pressure heads are generally stable based on data collected during the recharge period in year 2000 the response time of water table to recharge event was of 3 months the solid phase is in an advanced stage of weathering and quartz and kaolinite are principal minerals pore water has a low mineralization and can be characterized as ca hco 3 type with high concentrations of nitrate at shallow depth the main factors that have an impact on pore water chemistry are 1 atmospheric input and nitrate pollution due to human activities 2 evaporation down to a depth of 2 m 3 plant respiration down to a depth of 7 m 4 dissolution of primary silicate minerals such as feldspars and the formation of secondary minerals like kaolinite and 5 adsorption and cation exchange analysis of the solid phase suggests that ferric oxides and hydroxides provide the principal adsorption surfaces inverse geochemical modeling yielded non unique results and both dissolution precipitation of silicates plus cation exchange and dissolution precipitation of amorphous silica plus cation exchange were able to match changes of water chemistry along the presumed flow path

hydrogeochemical controls and usability of groundwater in the semi arid mayo tsanaga river basin far north province cameroon deuterium 18o major ions and dissolved silica in groundwater from semi arid mayo tsanaga river basin in the far north province cameroon were used to trace hydrogeochemical processes that control their concentrations and to explore for usability of the water electrical conductivity ranges from 57 2 581 s cm with alternating low and high values along the hydraulic gradient waters from piedmont alluvium show low concentrations in major cations which peak in mg within basalt na within plain alluvium and ca within basalt and the sandy limani yagoua ridge the initial dominant groundwater composition is cahco3 which did not evolve within the basalt and piedmont alluvium but evolved to nahco3 in the granite and plain alluvium the main processes controlling the major ions composition include the following 1 dissolution of silicates and fluorite 2 precipitation of fluorite and carbonate 3 cation exchange of ca in water for na in clay 4 and anthropogenic activities the d and 18o ratios vary from 35 to 0 7 and 5 3 to 1 1 respectively the lowest and highest isotope ratios are observed in groundwater within the downstream sandy limani yagoua ridge and the upstream graintes respectively variation in isotope ratios depends on altitude effect of 0 48 per 100 m between 600 and 850 m asl and on evaporation which had insignificant effect on the water salinity seventy percent of the groundwater shows poor drinking quality and 90 is suitable for irrigation

speleoseismology and palaeoseismicity of benis cave murcia se spain coseismic effects of the 1999 mula earthquake mb 4 8 this work describes the coseismic ceiling block collapse within benis cave 213 m murcia se spain associated with the 1999 mula earthquake mb 4 8 msk vii the collapse occurred at 156 m into the earthquake hall and as a consequence one small gallery became blind we studied the geology topography and active tectonic structures relevant to the cave in addition we carried out a seismotectonic analysis of the focal mechanism solutions and also a fault population analysis on slickensides measured in fault planes in the cave the stress and strain regime is interpreted as being congruent with the palaeoseismic evidence and agrees with the fault kinematics established for cave galleries developed within fault planes and growth anomalies of coral flowstone our analysis suggests that one active segment nne ssw determined the morphology and topography of the benis cave where strong to moderate palaeoearthquakes 6 m 7 took place as a consequence of this intense seismic activity a small gallery collapsed a new palaeoseismic structure or seismothem has been recognized namely the effect of palaeoearthquakes affecting the pattern of development of the spatial coral flowstone distribution located at the bottom of the cave

formation and preservation of pedogenic carbonates in south india links with paleo monsoon and pedological conditions clues from sr isotopes u th series and rees the influence of the pedogenic and climatic contexts on the formation and preservation of pedogenic carbonates in a climosequence in the western ghats karnataka plateau south west india has been studied along the climosequence the current mean annual rainfall mar varies within a 80 km transect from 6000 mm at the edge of the plateau to 500 mm inland pedogenic carbonates occur in the mar range of 500 1200 mm in the semi arid zone mar 500 900 mm carbonates occur i as rhick hardpan calcretes on pediment slopes and ii as nodular horizons in polygenic black soils i e vertisols in the sub humid zone mar 900 1500 mm pedogenic carbonates are disseminated in the black soil matrices either as loose irregular and friable nodules of millimetric size or as indurated botryoidal nodules of centimetric to pluricentimetric size they also occur at the top layers of the saprolite either as disseminated pluricentimetric indurated nodules or carbonate cemented lumps of centimetric to decimetric size chemical and isotopic sr 87 sr 86 compositions of the carbonate fraction were determined after leaching with 0 25 n hcl the corresponding residual fractions containing both primary minerals and authigenic clays were digested separately and analyzed the trend defined by the sr 87 sr 86 signatures of both labile carbonate fractions and corresponding residual fractions indicates that a part of the labile carbonate fraction is genetically linked to the local soil composition considering the residual fraction of each sample as the most likely lithogenic source of ca in carbonates it is estimated that from 24 to 82 55 on average of ca is derived from local bedrock weathering leading to a consumption of an equivalent proportion of atmospheric co2 these values indicate that climatic conditions were humid enough to allow silicate weathering mar at the time of carbonate formation likely ranged from 400 to 700 mm which is 2 to 3 fold less than the current mar at these locations the sr u and mg contents and the u 234 u 238 activity ratio in the labile carbonate fraction help to understand the conditions of carbonate formation the relatively high concentrations of sr u and mg in black soil carbonates may indicate fast growth and accumulation compared to carbonates in saprolite possibly due to a better confinement of the pore waters which is supported by their high u 234 u 238 signatures and or to higher content of dissolved carbonates in the pore waters the occurrence of ce mn and fe oxides in the cracks of carbonate reflects the existence of relatively humid periods after carbonate formation the carbonate ages determined by the u th method range from 1 33 0 84 kyr to 7 5 2 7 kyr and to a cluster of five ages around 20 kyr i e the last glacial maximum period the young occurrences are only located in the black soils which therefore constitute sensitive environments for trapping and retaining atmospheric co2 even on short time scales the maximum age of carbonates depends on their location in the climatic gradient from about 20 kyr for centimetric nodules at mule hole mar 1100 mm yr to 200 kyr for the calcrete at gundlupet mar 700 mm yr durand et al 2007 the intensity of rainfall during wet periods would indeed control the lifetime of pedogenic carbonates and thus the duration of inorganic carbon storage in soils c 2010 elsevier ltd all rights reserved

major ion chemistry of groundwater in a river basin a study from india groundwater is the prime source in the area of varaha river basin andhra pradesh india groundwater samples collected during pre and post monsoon were analyzed for major ion chemistry to understand the operating mechanism of geochemical processes for variation of groundwater quality low ionic concentration is observed in the groundwater occurring at topographic highs and towards the river compared to the rest of the area this is caused by the influence of recharge water geochemistry of groundwater is observed to be mainly controlled by the rock weathering mineral dissolution leaching ion exchange and evaporation and is subsequently modified by the anthropogenic and marine activities contribution of residual soluble salts below the depth of 5 m from the ground surface is high while it is low beyond the depth of 5 m anthropogenic activities cause an accumulation of excess residual soluble salts in the former depth and the content of this soluble matter is reduced by the clay products beyond the latter depth seasonal ionic concentration of groundwater is greatly influenced by the recharge process with reference to topographical features lithological characteristics and anthropogenic activities groundwater quality is classified as mixed and non carbonate alkali groups due to a combined action of geogenic anthropogenic and marine sources respectively the groundwater quality is above the adequacy level for both drinking and irrigation and appropriate management measures are recommended for sustainable development

association of hydrogeological factors in temporal variations of fluoride concentration in a crystalline aquifer in india the major part of groundwater in india is found in granitic aquifers fluoride in groundwater from a crystalline aquifer in a semi arid region of granitic rocks in india known as maheshwaram watershed was analyzed for spatial and temporal variability during 1999 2002 to assess the effect of hydrogeological factors on fluoride concentration samples were collected from 32 representative wells in the area for the pre and post monsoon seasons and analyzed for f content the chess computer program was used to calculate ionic activities of aqueous species and the mineral saturation index si for calcite and fluorite the gardenia computer program was used to calculate the recharge values in the study area the influences of dissolution kinetics of fluoride minerals and recharge from rainfall on fluoride concentration were of interest and results clearly indicate that fluoride content in groundwater depends on the interaction period of groundwater with host rock results could also be utilized for designing remedial measures particularly with dilution method in an optimal way

physical constraints on speleothem deformations caused by earthquakes seen from a new perspective implications for paleoseismology abstract fractured speleothems important earthquake environmental effects used in paleoseismological studies worldwide are particularly effective for dating here we discuss physical phenomena that can damage caves we supplement the discussion with information frequency characteristics and ground motion parameters from areas of mine openings threatened by induced seismicity as analogs of cave conduits as both from a physical point of view are underground voids affected by oscillations theoretical considerations indicate the use of bulk p wave and shear s wave moduli instead of young s modulus depending on the type of seismic wave affecting a given speleothem application of p wave and shear moduli enables the calculation of a speleothem s natural frequency based on measured p and s wave velocities as well as on the height and diameter of the speleothem the relationship between the natural frequency the acceleration causing speleothem failure and the height and diameter of speleothems has been determined moreover this acceleration value was compared to expected pga values in order to find similarities between the two acceleration values we highlight a phenomenon not previously considered in relation to cave environments i e tunnel waves which can appear in cave walls this effect significantly changes oscillation characteristics in a cave which can result in damage to speleothems which had not been expected to fail finally we present the potential for estimating the minimum magnitude required to damage a cave at a given distance from its source

using a structural approach to identify relationships between soil and erosion in a semi humid forested area south india biogeochemical and hydrological cycles are currently studied on a small experimental forested watershed 4 5 km 2 in the semi humid south india this paper presents one of the first data referring to the distribution and dynamics of a widespread red soil ferralsols and chromic luvisols and black soil vertisols and vertic intergrades cover and its possible relationship with the recent development of the erosion process the soil map was established from the observation of isolated soil profiles and toposequences and surveys of soil electromagnetic conductivity em31 geonics ltd lithology and vegetation the distribution of the different parts of the soil cover in relation to each other was used to establish the dynamics and chronological order of formation results indicate that both topography and lithology gneiss and amphibolite have influenced the distribution of the soils at the downslope the following parts of the soil covers were distinguished i red soil system ii black soil system iii bleached horizon at the top of the black soil and iv bleached sandy saprolite at the base of the black soil the red soil is currently transforming into black soil and the transformation front is moving upslope in the bottom part of the slope the chronology appears to be the following black soil bleached horizon at the top of the black soil streambed bleached horizon below the black soil it appears that the development of the drainage network is a recent process which was guided by the presence of thin black soil with a vertic horizon less than 2 in deep three distinctive types of erosional landforms have been identified 1 rotational slips type 1 2 a seepage erosion type 2 at the top of the black soil profile 3 a combination of earthflow and sliding in the non cohesive saprolite of the gneiss occurs at midslope type 3 types 1 and 2 erosion are mainly occurring downslope and are always located at the intersection between the streambed and the red soil black soil contact neutron probe monitoring along an area vulnerable to erosion types 1 and 2 indicates that rotational slips are caused by a temporary watertable at the base of the black soil and within the sandy bleached saprolite which behaves as a plane of weakness the watertable is induced by the ephemeral watercourse erosion type 2 is caused by seepage of a perched watertable which occurs after swelling and closing of the cracks of the vertic clay horizon and within a light textured and bleached horizon at the top of black soil type 3 erosion is not related to the red soil black soil system but is caused by the seasonal seepage of saturated throughflow in the sandy saprolite of the gneiss occurring at midslope c 2006 elsevier b v all rights reserved

present past and potential denudation rates is there a link tentative evidence from fission track data river sediment loads and terrain analysis in the south indian shield abstract ahnert ahnert f 1970 functional relationships between denudation relief and uplift in large mid latitude drainage basins am j sci 268 243 263 proposed that a denudation rate d could be predicted by the relation d 0 1535 h where h is local relief a substitute for mean slope the present study seeks to explore the value of this simple equation as a normative geomorphological tool in two successive and complementary stages its principles are applied to the western dharwar craton of south india first the robustness of local relief as a reliable substitute for mean slope is examined following the demonstration that the equation can successfully be used in the region of interest pending correction factors for rock resistance a potential denudation map of the western dharwar craton is established the pattern of potential denudation values is compared with known measurements of both long term 10 2 ma denudation rates inferred from apatite fission track data and modern 10 5 ma denudation rates derived from available sediment load measurements in relevant river basins unexpectedly close similarities between long term short term and potential denudation rates prompt a discussion on the merits of potential denudation as a possible standard in the appraisal of measured rates and as a tool for establishing permissible denudation rates when assessing the impact of man induced erosion a landscape specific basal metabolic rate of erosion is defined as a new concept the methodological pitfalls in extrapolating denudation rates from the measurement of sediment loads in rivers are reviewed and suggestions for tighter investigation are made

the characterization of steady state in earth surface systems findings from the gradient modelling of an indian climosequence abstract gradient modelling of a steep ecocline in south india has highlighted a suite of landscape units which appear to be entirely ordained by a simple water balance index this univariate climofunction is reflected in vegetation landform weathering and soil patterns although the vegetation successions are the most spectacular consistent pedogeomorphological trends were identified at several embedded scales of reality at the microscopic scale the existence of illite rich saprolite situated between the kaolinite dominated and smectite dominated core areas of the climosequence so far a missing mineralogical link only predicted by geochemical theory was effectively verified by field evidence at the megascopic scale the variation in topographic texture from polyconvex to polyconcave land systems via a convexo concave transition zone also suggests a strong relationship between hydroclimatic budgets and landforms such an exceptional environmental cabinet is well suited to reexamining other benchmark climosequences of the tropics and to readdressing the debated theories of climatic geomorphology by a discussion on the applicability of climax and steady state to tropical landforms

new empirical relationships among magnitude rupture length rupture width rupture area and surface displacement source parameters for historical earthquakes worldwide are compiled to develop a series of empirical relationships among moment magnitude m surface rupture length subsurface rupture length downdip rupture width rupture area and maximum and average displacement per event the resulting data base is a significant update of previous compilations and includes the additional source parameters of seismic moment moment magnitude subsurface rupture length downdip rupture width and average surface displacement each source parameter is classified as reliable or unreliable based on our evaluation of the accuracy of individual values only the reliable source parameters are used in the final analyses in comparing source parameters we note the following trends 1 generally the length of rupture at the surface is equal to 75 of the subsurface rupture length however the ratio of surface rupture length to subsurface rupture length increases with magnitude 2 the average surface displacement per event is about one half the maximum surface displacement per event and 3 the average subsurface displacement on the fault plane is less than the maximum surface displacement but more than the average surface displacement thus for most earthquakes in this data base slip on the fault plane at seismogenic depths is manifested by similar displacements at the surface log linear regressions between earthquake magnitude and surface rupture length subsurface rupture length and rupture area are especially well correlated showing standard deviations of 0 25 to 0 35 magnitude units most relationships are not statistically different at a 95 significance level as a function of the style of faulting thus we consider the regressions for all slip types to be appropriate for most applications regressions between magnitude and displacement magnitude and rupture width and between displacement and rupture length are less well correlated and have larger standard deviation than regressions between magnitude and length or area the large number of data points in most of these regressions and their statistical stability suggest that they are unlikely to change significantly in response to additional data separating the data according to extensional and compressional tectonic environments neither provides statistically different results nor improves the statistical significance of the regressions regressions for cases in which earthquake magnitude is either the independent or the dependent parameter can be used to estimate maximum earthquake magnitudes both for surface faults and for subsurface seismic sources such as blind faults and to estimate the expected surface displacement along a fault for a given size earthquake

water balance modelling in a tropical watershed under deciduous forest mule hole india regolith matric storage buffers the groundwater recharge process accurate estimations of water balance are needed in semi arid and sub humid tropical regions where water resources are scarce compared to water demand evapotranspiration plays a major role in this context and the difficulty to quantify it precisely leads to major uncertainties in the groundwater recharge assessment especially in forested catchments in this paper we propose to assess the importance of deep unsaturated regolith and water uptake by deep tree roots on the groundwater recharge process by using a lumped conceptual model comfort the model is calibrated using a 5 year hydrological monitoring of an experimental watershed under dry deciduous forest in south india mule hole watershed the model was able to simulate the stream discharge as well as the contrasted behaviour of groundwater table along the hillslope water balance simulated for a 32 year climatic time series displayed a large year to year variability with alternance of dry and wet phases with a time period of approximately 14 years on an average input by the rainfall was 1090 mm year 1 and the evapotranspiration was about 900 mm year 1 out of which 100 mm year 1 was uptake from the deep saprolite horizons the stream flow was 100 mm year 1 while the groundwater underflow was 80 mm year 1 the simulation results suggest that i deciduous trees can uptake a significant amount of water from the deep regolith ii this uptake combined with the spatial variability of regolith depth can account for the variable lag time between drainage events and groundwater rise observed for the different piezometers and iii water table response to recharge is buffered due to the long vertical travel time through the deep vadose zone which constitutes a major water reservoir this study stresses the importance of long term observations for the understanding of hydrological processes in tropical forested ecosystems c 2009 elsevier b v all rights reserved

stable isotopic and geochemical characteristics of groundwater in kherlen river basin a semi arid region in eastern mongolia summary inorganic solute ion concentrations and stable isotopes of oxygen and hydrogen in groundwater river water and precipitation were investigated to gain insight into the groundwater recharge process in the kherlen river basin a semi arid region in eastern mongolia the solute constituents in the river water main stream were of ca hco3 type spatially invariant and low in concentration groundwater in the upstream region was also characterized by a ca hco3 type though all ion concentrations were higher than in the river water on the other hand the chemical composition of the groundwater in the midstream region southern and eastern was spatially variable and the na mg2 cl and hco 3 concentrations were considerably higher than in the river water and upstream groundwater the stable isotopic compositions showed an evaporation effect on the groundwater and river water as well as an altitude effect in the precipitation and river water preferential recharge by relatively large rainfall events is thought to have caused the depleted isotopic ratio in the groundwater in the dry regions the stable isotope chemical and hydrological data suggest that the main stream water of the kherlen river is recharged by precipitation that falls in a headwater region at an altitude of more than 1650 m and that the interaction between the groundwater and river water is not dominant in the midstream and downstream regions of the river basin

geochemistry and origin of ferruginous nodules in weathered granodioritic gneisses mysore plateau southern india fe nodules occur within saprolites formed from weathering of granodioritic gneisses in the rain shadow region of the mysore plateau adjacent to the sahyadri mountains in southern india these nodules and their host saprolites were studied for their geochemistry including chemical speciation to understand nodule formation and chemical redistribution processes during rock weathering from their mode of occurrence and mineralogical and geochemical data we infer that the nodules originated by a two stage process in which the initial extensive weathering of gneisses likely facilitated subsequent ferrolysis weathering and nodule formation nodules originated by precipitation of goethite hematite and gibbsite along with several amorphous phases within the matrix of weathered gneisses this is possible only under hydromorphic conditions suggesting that parts of the plateau must have gone through a humid phase prior to the present aridity in the saprolites al fe and ti become enriched because of the removal of si ca na and k however within the nodule fe ti cr and ni are deposited after their chemical transport from the saprolite titanium known for its immobile nature was also mobilized and concentrated under the conditions of nodule formation the most important elements in the nodule constitution are fe al ti and mn each having both crystalline and amorphous phases fe ti and mn oxyhydroxides grain coatings in the saprolites and discrete amorphous mn and ti phases in the nodules seem to have scavenged trace elements from the weathering profile ree were mobilized during weathering and nodule genesis in which ce and ti show a strong geochemical coherence the enrichment of only hree in saprolite and both hree and lree with significant ce in the nodule indicate the control of evolving secondary minerals in the ree redistribution during rock weathering strong enrichment of ce in the weathering profile and in nodules has important implications to the ree chemistry of river waters

soils and climatic geomorphology on the karnataka plateau peninsular india abstract as a result of extensive field reconnaissance in southern india a geographical traverse across the planation surface of the karnataka uplands which lie in the rainshadow of the western ghats was selected to assess the consequences of a steep rainfall gradient on soil and landform patterns the study of the traverse described in detail reveals a characteristic progression of soil type and wash divide form from the high rainfall to the semi arid end of the continuum and invites a critical reappraisal of classical notions in climatic geomorphology and the soil sciences the assumption that alternations of wet and dry climates are necessary to achieve planation is given special consideration and the often held belief that kaolinite minerals are diagnostic of humid palaeoclimates when found in a semi arid climate is challenged the findings for the indian traverse are set against the better known data for west africa where the rainfall range between the gulf of guinea and the sahel is comparable with that observed in the south western deccan differences outweighing similarities attention is drawn to the possibility that tectonic regime which also controls the degree of landscape stripping is a major key to understanding the climatic geography of soils the tread of planation surfaces and the shape of hillslopes from one region of the tropics to another

isotopic geochemistry of the groundwater system in arid and semiarid areas and its significance a case study in shiyang river basin gansu province northwest china shiyang river basin located in the eastern part of hexi corridor in the middle gansu province nw china is a typical arid to semiarid area within its drainage distance of merely 300 km the groundwater system shows a gradual hydrochemical zonation from the upper reach to the lower reach which is composed of hydrocarbonate sulfate to chloride zones respectively variation in the saturation index si of calcite and dolomite shows that under arid to semiarid conditions the drastic evaporation causes the groundwater quality to deteriorate in the lower reach isotopic compositions of h o and he in the groundwater show that the groundwater recharge sources are mainly from meteoric water 3he 3he 20ne coordinates could clearly distinguish the water sources and mixing among them in the caiqi region there is apparent mixing of the crevice water containing excess 4he with the overlying groundwater which also implies a much lower circulation rate of the groundwater fairly high 3he 4he ratios of the groundwaters collected from the adjacent area of hidden faults along qilian mountains show the eminent input of mantle derived helium indicating that these faults not only cut the crust deeply but are currently active

an application of the slip model of brittle deformation to focal mechanism analysis in three different plate tectonic situations abstract the slip model of brittle deformation reches 1983 imposes a set of constraints on the angular relationships between faults their striations on slickensides and the type and orientation of the deformation ellipsoid in focal mechanisms of earthquakes these relationships can be used to determine which of the two nodal planes is the fault plane and then to obtain the strain ellipsoid of regional tectonic deformation controlling seismicity in this approach it is convenient to use pitch dip diagrams de vicente 1988 and p t diagrams angelier and mechler 1977 both developed for fault population analysis in this paper three regions in different plate tectonic situations are analysed using these methods these regions are a zone of intracontinental seismicity in the eastern peruvian andes a zone of continental compressional deformation in the iranian plateau and the fenwei graben of china nodal planes of focal mechanisms published in different papers about seismicity in these regions have been used the following conclusions being reached in the analysed zone of the peruvian andes three regional deformation types appear causing fault movements that range from slightly reverse strike slip to reverse strike slip in addition exclusively at depths in excess of 18 km there is a deformation of an uniaxial shortening type in all of these deformations the horizontal shortening axis is oriented from n87 to n93 in the iranian plateau two horizontal shortening directions appear n151 and n61 even showing faults that imply an uniaxial deformation ellipsoid the shortening axis of which is at n61 in the fenwei graben the ellipsoid of regional deformation has a stretching principal axis at n145 150 and a shortening axis at n55 60 the strike slip movement along faults being as important as the normal one

regolith mass balance inferred from combined mineralogical geochemical and geophysical studies mule hole gneissic watershed south india the aim of this study is to propose a method to assess the long term chemical weathering mass balance for a regolith developed on a heterogeneous silicate substratum at the small experimental watershed scale by adopting a combined approach of geophysics geochemistry and mineralogy we initiated in 2003 a study of the steep climatic gradient and associated geomorphologic features of the edge of the rifted continental passive margin of the karnataka plateau peninsular india in the transition sub humid zone of this climatic gradient we have studied the pristine forested small watershed of mule hole 4 3 km2 mainly developed on gneissic substratum mineralogical geochemical and geophysical investigations were carried out i in characteristic red soil profiles and ii in boreholes up to 60 m deep in order to take into account the effect of the weathering mantle roots in addition 12 electrical resistivity tomography profiles ert with an investigation depth of 30 m were generated at the watershed scale to spatially characterize the information gathered in boreholes and soil profiles the location of the ert profiles is based on a previous electromagnetic survey with an investigation depth of about 6 m the soil cover thickness was inferred from the electromagnetic survey combined with a geological pedological survey taking into account the parent rock heterogeneity the degree of weathering of each of the regolith samples has been defined using both the mineralogical composition and the geochemical indices loss on ignition weathering index of parker chemical index of alteration comparing these indices with electrical resistivity logs it has been found that a value of 400 ohm m delineates clearly the parent rocks and the weathered materials then the 12 inverted ert profiles were constrained with this value after verifying the uncertainty due to the inversion procedure synthetic models based on the field data were used for this purpose the estimated average regolith thickness at the watershed scale is 17 2 m including 15 2 m of saprolite and 2 m of soil cover finally using these estimations of the thicknesses the long term mass balance is calculated for the average gneiss derived saprolite and red soil in the saprolite the open system mass transport function indicates that all the major elements except ca are depleted the chlorite and biotite crystals the chief sources for mg 95 fe 84 mn 86 and k 57 biotite only are the first to undergo weathering and the oligoclase crystals are relatively intact within the saprolite with a loss of only 18 the ca accumulation can be attributed to the precipitation of caco3 from the percolating solution due to the current and or the paleoclimatic conditions overall the most important losses occur for si mg and na with 286 106 mol ha 62 of the total mass loss 67 106 mol ha 15 of the total mass loss and 39 106 mol ha 9 of the total mass loss respectively al fe and k account for 7 4 and 3 of the total mass loss respectively in the red soil profiles the open system mass transport functions point out that all major elements except mn are depleted most of the oligoclase crystals have broken down with a loss of 90 the most important losses occur for si na and mg with 55 106 mol ha 47 of the total mass loss 22 106 mol ha 19 of the total mass loss and 16 106 mol ha 14 of the total mass loss respectively ca al k and fe account for 8 6 4 and 2 of the total mass loss respectively overall these findings confirm the immaturity of the saprolite at the watershed scale the soil profiles are more evolved than saprolite but still contain primary minerals that can further undergo weathering and hence consume atmospheric co2

nd isotopes of siliciclastic rocks from tibet western china constraints on provenance and pre cenozoic tectonic evolution nd isotope data from pre cenozoic siliciclastic rocks from tibet are used to determine variations of source regions with time and hence tectonic history on average the tdm and tchur ages of the tibetan samples are up to 1 83 0 36 ga and 1 25 0 45 ga respectively indicating that tibet is underlain by lower proterozoic basement and has close affinity with the himalayas an nd isotope crisis occurred at the early permian with older samples defining a trend of slight decrease in end values with time while the lower permian rocks sharply increasing 6 5 end units this is related to the coeval widespread basaltic magmatism in tibet which could be responsible for tibet rifting away from northern gondwanaland the central qiangtang meta sedimentary samples have distinct nd isotope characteristics end 0 19 87 1 51 tdm 2 07 0 13 ga tchur 1 78 0 21 ga from the songpan ganzi samples end 0 12 77 2 87 tdm 1 49 0 18 ga tchur 1 08 0 23 ga suggestive that these two groups were derived from differentsourcesandthatthe former werenot theequivalents ofthe latterthat wasunderthrust fromthe jinsasuture andmayrepresent subducted continental crust the mid jurassic flysch rocks in northern lhasa have typical upper crust nd isotopic signatures and could have formed under a passive margin environment their bangong counterparts averagely 6 35 units higher in end values unveil derivations from a likely magmatic arc along the northern bangong margin basaltic pebblewith low nd content and endvalue from the berriasian valanginian rocks in central tibet along with the samples with generally high end values shows that the bangong ophiolites could have been a main source of sediments during the earliest cretaceous time a significant transition of sediment sources occurred at the beginning of the hauterivian stage 120 ma sedimentary basaltic tuff end t 2 27 in the hauterivian lower cenomanian samples in central tibet and common nd signatures for input of mantle like materials in these rocks indicate that mantle derived magmatic rocks could have constituted a significant source the huge hauterivian lower cenomanian sediments in central tibet are thus inferred to have been accumulated under a back arc rifting setting 2007 elsevier b v all rights reserved

hydrogeological and mixing process of waters in aquifers in arid regions a case study in san luis potosi valley mexico the climatic conditions of arid regions are characterized by high temperatures low precipitation and high evapotranspiration rates that can explain the reduced recharge of aquifers thus in these regions there are some problems related to the groundwater quality and recharge that makes worse the problem of groundwater supply a model taking into account ternary mixtures is presented and applied to a case study the aquifer of san luis potosi valley located in the highlands of the central part of mexico in this valley four hydrochemical facies were identified that correspond to the ca na k hco3 na k ca hco3 ca hco3 and ca so4 types from this characterization it was found out that the recharge area known as bledos graben is located at the se of the valley the deep water flow comes from there villa de reyes and alvarez range to the center of the valley mixture fractions were obtained by using chlorides and fluorides as conservative elements from which it was possible to quantify the contribution of each member to the groundwater quality according to these results the contributions to the water extracted from this aquifer are as follows shallow flows 50 deep flows from villa de reyes 27 and flows coming from the alvarez ranges about 15

influence of hydrogeochemical processes on temporal changes in groundwater quality in a part of nalgonda district andhra pradesh india geochemical processes that take place in the aquifer have played a major role in spatial and temporal variations of groundwater quality this study was carried out with an objective of identifying the hydrogeochemical processes that controls the groundwater quality in a weathered hard rock aquifer in a part of nalgonda district andhra pradesh india groundwater samples were collected from 45 wells once every 2 months from march 2008 to september 2009 chemical parameters of groundwater such as groundwater level ec and ph were measured insitu the major ion concentrations such as ca2 mg2 na k cl and so42 were analyzed using ion chromatograph co3 and hco3 concentration was determined by acid base titration the abundance of major cation concentration in groundwater is as na ca2 mg2 k while that of anions is hco3 so42 cl co3 ca hco3 na cl ca na hco3 and ca mg cl are the dominant groundwater types in this area relation between temporal variation in groundwater level and saturation index of minerals reveals the evaporation process the ion exchange process controls the concentration of ions such as calcium magnesium and sodium the ionic ratio of ca mg explains the contribution of calcite and dolomite to groundwater in general the geochemical processes and temporal variation of groundwater in this area are influenced by evaporation processes ion exchange and dissolution of minerals

pedogenic carbonates on precambrian silicate rocks in south india origin and paleoclimatic significance abstract calcrete in alfisols on precambrian silicate rocks is studied here in an attempt to reconstruct paleorainfall trends in semiarid south india facies of observed carbonate accumulation are pseudomycelium calcrete nodules nodular horizons hardpan and laminar horizons based on geochemical and sr isotope tracing we relate the presence of calcrete to local geologic conditions within the precambrian basement notably discrete ca rich metamorphic outcrops and rule out eolian input micromorphologic analysis reveals a multi stage origin of the calcretes involving soil colluvial geochemical and biologic processes mostly in vadose environments preliminary u th ages of 190 200 ka obtained on calcrete nodules suggest a major phase of ca release rock weathering and precipitation during marine oxygen isotope stage 7 the calcrete thus indicates fairly stable semiarid conditions at the 200 ky time scale despite fluctuations around an annual rainfall average close to current values 700 mm the stability of the western ghats barrier as a shield to the southwest monsoon explains the long term average stability of the pedoclimatic environment in the rainshadow zone the radiometric ages suggest that weathering may occur massively at discrete intervals of geologic history during spikes of humidity in the paleoclimatic record the rest of the time is spent recycling and redistributing the products of weathering incrementally at landscape scale within seasonal cycles of a relatively stable semi arid climate dating the calcrete therefore does not equate with dating the soil but instead the residence times of nodules in a dynamic soil system in which different constituents have different turnover rates

assessment of hydrogeochemistry and contamination of varamin deep aquifer tehran province iran the present study investigates the hydrogeochemistry and contamination of varamin deep aquifer located in the southeast of tehran province iran the study also evaluates groundwater suitability for irrigation uses the hydrogeochemical study was conducted by collecting and analyzing 154 groundwater samples seasonally during 2014 based on evolutionary sequence of chebotarev the aquifer is in the stage of so4 hco3 in the north half of the plain and it has evolved into so4 cl in the south half the unusual increase in tds and cl toward the western boundaries of the aquifer indicates some anomalies these anomalies have originated from discharge of untreated wastewater of tehran city in these areas the studied aquifer contains four dominant groundwater types including na ca so4 55 na ca hco3 22 na cl 13 and ca cl 10 the spatial distributions of na cl and ca cl water types coincide with observed anomalies ionic relationships of so4 2 versus cl and na versus cl confirm that water rock interaction and anthropogenic contribution are main sources of these ions in the groundwater the main processes governing the chemistry of the groundwater are the dissolution of calcite dolomite and gypsum along the flow path and direct ion exchange reverse ion exchange controls the groundwater chemistry in the areas contaminated with untreated wastewater based on na and sar 10 3 and 27 of water samples are unsuitable for irrigation purposes respectively regarding residual sodium carbonate there is no treat for crop yields only 6 of water samples represent magnesium adsorption ratios more than 50 which are harmful and unsuitable for irrigation

landscape response to strike slip faulting linked to collisional settings quaternary tectonics and basin formation in the eastern betics southeastern spain abstract neotectonic behaviour of the eastern betics southeastern spain has been controlled by the presence of a large left lateral shear zone this is an intraplate transcurrent zone probably decoupled by a mid crustal detachment horizon the morphological expression of this crustal structure is a sigmoidal corridor in which the main quaternary basins are located three types of morphostructural domains can be distinguished in the sigmoidal corridor the central segment and the northern and southern terminal splays the central segment is characterized by wrench tectonics whilst the southern and northern terminal splays are controlled by transtensional and transpressional tectonics respectively the quaternary morphostructural pattern is only the more recent picture of the tectonic processes that have controlled the late orogenic evolution of the eastern betics the indentation of the aguilas arc accompanied by thin skinned thrusting and tectonic escape in its easternmost sector and extensional collapse accompanied by thin skinned stretching in its westernmost sector

contributions of water rock interactions to the composition of groundwater in areas with a sizeable anthropogenic input a case study of the waters of the fundao area central portugal we used a combination of a grouping algorithm and a weathering algorithm to assess the contributions made by chemical weathering and anthropogenic inputs to the groundwater composition in a granitoid area the first algorithm is based on the mathematical concept of equivalent relations between objects and is used to find groups of water samples using the grouping algorithm we identified groups with similar chemistries in a set of data relating to the water composition in 160 springs and wells in the fundao area portugal the second algorithm is based on stoichiometries mass and charge balances in weathering reactions and is used to relate the water composition of each identified group to water mineral interactions in the area background information on the petrology and mineralogy of the area allowed us to choose the most realistic water mineral interactions we also had information about the use and composition of fertilizers in this agricultural area in applying the weathering algorithm we considered all dissolved silica and bicarbonate to be produced by chemical weathering and all dissolved chloride sulphate and nitrate to be derived from other sources mainly from fertilizers the anthropogenic contributions to the water chemistries in the area are high despite the high background concentrations derived from pollution we were able to assess the contribution of weathering to the water chemistries we obtained realistic results with the two algorithms supported by the fact that the spatial distribution of the samples belonging to the various groups shows a good correlation with the geology and petrology of the area

geochemical characteristics of groundwater in different climatic zones of sri lanka sri lanka is characterized by well demarcated climatic zones based on the rainfall pattern known as wet zone dry zone and intermediate zone groundwaters in these three zones are extracted mainly for drinking and irrigation from metamorphic hard rock aquifers and saprolite developed on metamorphic rocks detailed hydrogeochemical investigations were carried out covering these three climatic zones in order to characterize the groundwater a total of 166 groundwater samples were collected representing three climatic zones and analyzed for their major and trace element geochemistry the results indicate a clear difference in the geochemistry of groundwater between climatic regions whereas semiarid dry zone groundwater is characterized with higher dissolved mineral contents compared that of the wet and intermediate zones low ph levels were noticed in the wet zone areas while high calcium and fluoride contents were observed in the dry and intermediate terrains remarkably high phosphate contents were observed in all three regions indicating the influence of fertilizer application on groundwater particularly in the dry zone regions the groundwater chemistry is mainly controlled by rock water interactions and ion exchange processes in which high mineral contents are added from underlying metamorphic rocks to the drinking and irrigation water the results indicate that groundwater in the dry zone area is under stress compared to other climate areas but in the wet zone groundwater shows remarkable influence of anthropogenic activities

characterization of seasonal local recharge using electrical resistivity tomography and magnetic resonance sounding a groundwater recharge process of heterogeneous hard rock aquifer in the moole hole experimental watershed south india is being studied to understand the groundwater flow behaviour significant seasonal variations in groundwater level are observed in boreholes located at the outlet area indicating that the recharge process is probably taking place below intermittent streams in order to localize groundwater recharge zones and to optimize implementation of boreholes a geophysical survey was carried out during and after the 2004 monsoon across the outlet zone magnetic resonance soundings mrs have been performed to characterize the aquifer and measure groundwater level depletion the results of mrs are consistent with the observation in boreholes but it suffers from degraded lateral resolution a better resolution of the regolith bedrock interface is achieved using electrical resistivity tomography ert ert results are confirmed by resistivity logging in the boreholes ert surveys have been carried out twice before and during the monsoon across the stream area the major feature of recharge is revealed below the stream with a decrease by 80 of the calculated resistivity the time lapse ert also shows unexpected variations at a depth of 20 m below the slopes that could have been interpreted as a consequence of a deep seasonal water flow however in this area time lapse ert does not match with borehole data numerical modelling shows that in the presence of a shallow water infiltration an inversion artefact may take place thus limiting the reliability of time lapse ert a combination of ert with mrs provides valuable information on structure and aquifer properties respectively giving a clue for a conceptual model of the recharge process infiltration takes place in the conductive fractured fissured part of the bedrock underlying the stream and clayey material present on both sides slows down its lateral dissipation

hydrogeochemical evaluation of groundwater in the lower offin basin ghana alumino silicate mineral dissolution cation exchange reductive dissolution of hematite and goethite oxidation of pyrite and arsenopyrite are processes that influence groundwater quality in the offin basin the main aim of this study was to characterise groundwater and delineate relevant water rock interactions that control the evolution of water quality in offin basin a major gold mining area in ghana boreholes dug wells springs and mine drainage samples were analysed for major ions minor and trace elements major ion study results show that the groundwater is principally ca mg hco3 or na mg ca hco3 in character mildly acidic and low in conductivity groundwater acidification is principally due to natural biogeochemical processes though acidic the groundwater has positive acid neutralising potential provided by the dissolution of alumino silicates and mafic rocks trace elements loading except arsenic and iron of groundwater is generally low reductive dissolution of iron minerals in the presence of organic matter is responsible for high iron concentration in areas underlain by granitoids elsewhere pyrite and arsenopyrite oxidation is the plausible process for iron and arsenic mobilisation approximately 19 and 46 of the boreholes have arsenic and iron concentrations exceeding the who s guidelines for drinking water quality final task group meeting who press world health organization geneva 2004 maximum acceptable limits of 10 g l 1 and 0 3 mg l 1 for drinking water

chemical weathering of carbonates and silicates in the han river basin south korea abstract a detailed investigation of the fluvial geochemistry of the han river system allows to estimate the rates of chemical weathering and the consumption of co 2 the han river drains approximately 26 000 km 2 and is the largest river system in south korea in terms of both water discharge and total river length it consists of two major tributaries the north han river nhr and the south han river shr distinct differences in basin lithology silicate vs carbonate between the nhr and shr provide a good natural laboratory in which to examine weathering processes and the influence of basin geology on water quality the concentrations of major elements and the sr isotopic compositions were obtained from 58 samples collected in both summer and winter along the han river system in both 2000 and 2006 the concentrations of dissolved loads differed considerably between the nhr and shr compared with the shr the nhr had much lower total dissolved solids tds sr and major ion concentrations but a higher si concentration and 87 sr 86 sr ratio a forward model showed that the dissolved loads in the nhr came primarily from silicate weathering 55 11 with a relatively small portion from carbonates 30 14 whereas the main contribution to the dissolved loads in the shr was carbonate weathering 82 3 with only 11 4 from silicates these results are consistent with the different lithologies of the two drainage basins silicate rocks in the nhr versus carbonate rocks in the shr sulfuric acid derived from sulfide dissolution in coal containing sedimentary strata has played an important role in carbonate weathering in the shr basin unlike in the nhr basin the silicate weathering rate swr was similar between the nhr and shr basins but the rate of co 2 consumption in the shr basin was lower than in the nhr basin due to an important role of sulfuric acid derived from pyrite oxidation

combined estimation of specific yield and natural recharge in a semi arid groundwater basin with irrigated agriculture a water budget approach is developed to jointly estimate specific yield and natural recharge in an unconfined aquifer with significant seasonal water table fluctuations water table fluctuations are due to distinct seasonality in groundwater recharge the separation of the hydrologic year into two or more extended seasons of recharge wet season and no recharge dry season with accompanying changes in water table allows for a split use of the water table fluctuation wtf method first to estimate specific yield from the water table drop during the dry season no recharge and second to estimate recharge from the water table rise during the wet season after considering all other water budget components explicitly the latter includes explicit computation of groundwater storage with the wtf method the application of the wtf method requires a large number of water level measurements throughout the unconfined aquifer before and after each season the advantage of the method is that specific yield and recharge are estimated at the scale of interest to basin hydrologic studies and that the method requires no extensive in situ instrumentation network here the method is demonstrated through a case study in a fractured hard rock aquifer subject to intensive groundwater pumping for irrigation purposes

understanding hydrological processes in a highly stressed granitic aquifer in southern india the results of a study evaluating the recharge discharge conditions of an unconfined stressed granitic aquifer situated in a semi arid region of andhra pradesh southern india are presented over the last three decades excessive withdrawal of groundwater has drastically lowered the water table to the bedrock the watershed studied was divided into four zones based on geomorphology and hydrogeological conditions using environmental chloride data pertaining to groundwater soil depth profiles and some hydrogeologic and hydrochemical observations a recharge model for the watershed was developed the model revealed that the bulk of the vertical recharge in the western elevated land occurs through preferred pathways and that a small fraction occurs through the soil matrix in addition the watershed has a poor hydrogeologic fabric as indicated by the small range of matrix flow recharge 1 to 1 5 of rainfall among the four zones the dominating preferential flow was high 16 of the annual average rainfall in the valley fills but decreased to 5 5 5 in the plains furthermore although the bulk of the recharge occurs vertically considerable lateral movement of groundwater down the slope indicates that sequential hydrochemical changes occur distinct geomorphological features that exist in the watershed support the proposed model situations similar to those described above may exist in numerous watersheds in the granitic hard rock region therefore information obtained from investigations conducted in this watershed can aid in the development of plans enabling the sustainable exploitation of watersheds that have not yet been developed as well as implementation of appropriate rainwater conservation measures in over exploited watersheds copyright 2009 john wiley sons ltd

denudation history of the continental margin of western peninsular india since the early mesozoic reconciling apatite fission track data with geomorphology a comprehensive apatite fission track aft study of the passive margin of western peninsular india between 12 and 16 n is used to reconstruct the denudation chronology of the continental hinterland in common with other rifted margins the morphology is characterised by a low lying coastal plateau separated from an elevated inland plateau by an erosionally controlled escarpment western ghats we modelled the fission track data using the commonly adopted annealing algorithm of laslett et al chem geol 65 1987 1 13 using the default parametrisation i e an initial track length of 16 3 m it was found that during the mesozoic denudation rates remained extremely low increasing sporadically when erosion peaked at 130 ma rifting with antarctica and 80 ma rifting with madagascar denudation rates rose considerably during the cenozoic reaching maxima of ca 120 m myr such values are however considered as major overestimates and the effects of the seychelles rifting at 65 ma remain suspiciously unrecorded we explored the consequences of changing the initial track length in this model to a value of 14 5 m in practice this reduces the rapid cenozoic denudation artefact model peak rates during the mesozoic are much more variable and during the cenozoic reach values an order of magnitude lower than with the original initial track length the response to the seychelles rifting event is almost immediate just as previous model calibrations in aft analysis have been relatively empirical this revised approach does not provide insights into the physical mechanisms of low temperature annealing however it is shown to agree much better with independently established geomorphic cosmogenic stratigraphic and tectono magmatic evidence in this and other stable shield regions in terms of both the timing and the magnitude of geological events and the geomorphic response of the landscape to them

broken speleothems reveal holocene and late pleistocene paleoearthquakes in northern calabria italy two underground cavities in the northern calabria region the romito and the san paolo caves have been selected for speleoseismic analysis in order to provide a timeframe for paleoearthquakes which have shocked the cave sites and the surrounding area the caves are positioned in a seismogenically active region which has been struck by medium to large earthquakes in historical and pre historic times moreover frequent instrumentally measured small to moderate seismicity occurs in the area m 5 6 we document damaged carbonate cave deposits including collapsed and broken stalactites in situ severed stalagmites and stalactites and collapsed bedrock ceilings samples were sawed in order to expose breakages and contacts within the laminae sixteen laminae eight pairs of pre and post event laminae were drilled for dating by the uraniumthorium disequilibrium technique three discrete events were defined by six of the speleoseismites to i 7 4 2 9 ka ii 9 7 8 2 ka and iii 28 4 27 4 ka two additional speleoseismites gave wide age brackets but are confined to 65 7 18 6 ka which overlaps with event iii but might represent additional events the present speleoseismic work depicts a scenario of a minimum of three well constrained strong shaking events in a time span of the past 28 ky yielding a maximum recurrence interval of 9 ky in 2012 the area was shaken by a mw5 2 earthquake that apparently did not produced damage within the study cavities suggesting that this size is a lower magnitude limit for producing permanent effects in the caves deposits the speleoseismites we studied collected must have been generated by larger magnitude events and or with different epicenter locations this study adds medium or large earthquake events previously lacking to the historic and instrumental record this may contribute to reduction of gaps in the earthquake record and consequently a more reliable recurrence interval estimate for damaging earthquakes in the region

new insights on speleoseismology the geothermal gradient and heat flow values in caves for the study of active faults abstract normally in paleoseismology the study of the tectonic slip rate is performed in trenches on the fault scarp or by the estimation of fault movements from the geomorphic features in this work we have carried out a paleoseismic analysis of the benis fault located in southeast spain combined with a geothermal analysis inside a deep cave related to the fault 350 m thus we have estimated the last earthquake magnitude and time of occurrence from evidence of ceiling collapse and displaced carbonate blocks inside a cave which is developed across the fault the magnitude was obtained from the application of the empirical relationship of the fault parameters and coseismic vertical displacement yielding a value ranging between m 5 9 and m 6 5 moreover we dated this paleoearthquake by the paleontological record of a lynx pardinus spelaea with an age of 65 18 ka bp additionally we have measured the thermal profile of the benis cave 350 m of depth from single rock point temperature measurements during 2 years the temperature profile shows three different parts inside the cave the shallow heterogeneous thermal zone till 50 m depth the homogeneous thermal zone 150 m till with constant temperature and the hetero thermal deep zone deeper than 150 m and till the deepest zone 350 m furthermore we have estimated the vertical geothermal gradient 1 85 c 100 m for the deepest zone 150 290 m the temperature increases with depth showing a reverse thermal profile in comparison with normal gradients in deep caves finally we have calculated the heat flux of 0 46 mwm 2

modeling of karst aquifer genesis influence of exchange flow 1 this paper presents a numerical model study simulating the early karstification of a single conduit embedded in a fissured system a hybrid continuum discrete pipe flow model cave is used for the modeling the effects of coupling of the two flow systems on type and duration of early karstification are studied for different boundary conditions assuming fixed head boundaries at both ends of the conduit coupling of the two flow systems via exchange flow between the conduit and the fissured system leads to an enhanced evolution of the conduit this effect is valid over a wide range of initial conduit diameters and karstification is accelerated by a factor of about 100 as compared to the case of no exchange flow parameter studies reveal the influence of the exchange coefficient and of the hydraulic conductivity of the fissured system on the development time for the conduit in a second scenario the upstream fixed head boundary is switched to a fixed flow boundary at a specified flow rate during the evolution limiting the amount of water draining toward the evolving conduit depending on the flow rate specified conduit evolution may be slowed down or greatly impaired if exchange flow is considered

faulting parameters of the 1999 mula earthquake southeastern spain abstract the seismicity of southern spain is characterized by low to moderate earthquake activity magnitudes

palaeoseismicity from karst sediments the grotta del cervo cave case study central italy karst speleothems can be used for tectonic and palaeoseismic analyses in particular stalagmites can be treated as the records of a natural pendulum samples of stalagmites from the grotta del cervo and the grotta a male caves central italy have been dated using 14c and u th radiometric methods the present paper shows the limits and validity of such methods for dating strong earthquakes of the past in particular radiometric 14c dating shows that the youngest general stalagmitic collapse observed inside the grotta del cervo cave must be related to the december 1456 earthquake of central italy

kinematics of the iberia maghreb plate contact from seismic moment tensors and gps observations the iberian peninsula and the maghreb experience moderate earthquake activity and oblique nw se convergence between africa and eurasia at a rate of 5 mm yr coeval extension in the alboran basin and a n35 e trending band of active left lateral shear deformation in the alboran betic region are not straightforward to understand in the context of regional shortening and evidence complexity of deformation at the plate contact we estimate 86 seismic moment tensors mw 3 3 to 6 9 from time domain inversion of near regional waveforms in an intermediate period band those and previous moment tensors are used to describe regional faulting style and calculate average stress tensors the solutions associated to the trans alboran shear zone show predominantly strike slip faulting and indicate a clockwise rotation of the largest principal stress orientation compared to the regional convergence direction 1 at n350 e at the n algerian and sw iberian margins reverse faulting solutions dominate corresponding to n350 e and n310 e compression respectively over most of the betic range and intraplate iberia we observe predominately normal faulting and wsw ene extension 3 at n240 e from gps observations we estimate that more than 3 mm yr of african nubian eurasian plate convergence are currently accommodated at the n algerian margin 2 mm yr in the moroccan atlas and 2 mm yr at the sw iberian margin 2 mm yr is a reasonable estimate for convergence within the alboran region while alboran extension can be quantified as 2 5 mm yr along the stretching direction n240 e superposition of both motions explains the observed left lateral transtensional regime in the trans alboran shear zone two potential driving mechanisms of differential motion of the alboran betic gibraltar domain may coexist in the region a secondary stress source other than plate convergence related to regional scale dynamic processes in the upper mantle of the alboran region as well as drag from the continental scale motion of the nubian plate along the southern limit of the region in the atlantic ocean the 3 5 mm yr westward motion of the gibraltar arc relative to intraplate iberia can be accommodated at the transpressive sw iberian margin while available gps observations do not support an active subduction process in this area

environmental geochemistry and quality assessment of surface and subsurface water of mahi river basin western india the hydrogeochemical study of surface and subsurface water of mahi river basin was undertaken to assess the major ion chemistry solute acquisition processes and water quality in relation to domestic and irrigation uses the analytical results show the mildly acidic to alkaline nature of water and dominance of na and ca2 in cationic and hco3 and cl in anionic composition in general alkaline earth elements ca2 mg2 exceed alkalis na k and weak acids hco3 dominate over strong acids so42 cl in majority of the surface and groundwater samples ca2 mg2 hco3 is the dominant hydrochemical facies both in surface and groundwater of the area the weathering of rock forming minerals mainly controlled the solute acquisition process with secondary contribution from marine and anthropogenic sources the higher concentration of sodium and dissolved silica high equivalent ratios of na k tz na k cl and low ratio of ca2 mg2 na k suggest that the chemical composition of the water is largely controlled by silicate weathering with limited contribution from carbonate weathering and marine and anthropogenic sources kaolinite is the possible mineral that is in equilibrium with the water implying that the chemistry of river water favors kaolinite formation assessment of water samples for drinking purposes suggests that the majority of the water samples are suitable for drinking at some sites concentrations of tds th f no3 and fe are exceeding the desirable limit of drinking however these parameters are well within the maximum permissible limit except for some cases to assess the suitability for irrigation parameters like sar rsc and na were calculated in general both surface and groundwater is of good to suitable category for irrigation uses except at some sites where high values of salinity na and rsc restrict its uses

quantitative and qualitative insights into bedrock landform erosion on the south indian craton using cosmogenic nuclides and apatite fission tracks due to the scarcity of datable chronostrati graphic markers and the related difficulties of quantifying depths of erosion in cratonic landscapes conceptual models of tropical pediplain and etchplain evolution commonly lack time and vertical elevation scales here we present the first quantitative study of relief development in south india based on in situ produced 10 be dating aided by previously acquired apatite fission track data erosion rates measured on the summits of inselbergs concur with the perception of inselbergs as islands of low erosion but they also reveal a critical contrast between slowly evolving 2 m m y higher relief landforms and more rapidly eroding 8 12 m m y lower relief landforms this relationship is independent of lithology and climate but suggests that erosion rates on the surrounding plain which are controlled by fluvial incision rates into the plateau surface feed back on inselberg dynamism a discussion on the most suitable sites for dating bedrock land forms highlights the problems of sampling design the difficulties of linking measured erosion rates to the minutiae of process and the limitations of both single and multiple chronometer denudation chronologies in low energy cratonic environments

characterization of groundwater chemistry under the influence of lithologic and anthropogenic factors along a climatic gradient in upper cauvery basin south india hydrogeological and climatic effect on chemical behavior of groundwater along a climatic gradient is studied along a river basin semi arid 500 800 mm of mean annual rainfall sub humid 800 1 200 mm year and humid 1 200 1 500 mm year are the climatic zones chosen along the granito gneissic plains of kabini basin in south india for the present analysis data on groundwater chemistry is initially checked for its quality using nicb ratio 40 of pollution and eliminated for the characterization piper s diagram with mean concentrations indicates the evolution of canahco3 semi arid from cahco3 humid zone along the climatic gradient carbonates dominate other anions and strong acids exceeded weak acids in the region mule hole sew an experimental watershed in sub humid zone is characterized initially using hydrogeochemistry and is observed to be a replica of entire sub humid zone with 25 wells extension of the studies for the entire basin 120 wells showed a chemical gradient along the climatic gradient with sub humid zone bridging semi arid and humid zones ca na molar ratio varies by more than 100 times from semi arid to humid zones semi arid zone is more silicaceous than sub humid while humid zone is more carbonaceous ca cl 14 along the climatic gradient groundwater is undersaturated humid saturated sub humid and slightly supersaturated semi arid with calcite and dolomite concentration depth profiles are in support of the geological stratification i e 18 m of saprolite and 25 m of fracture rock with parent gneiss beneath all the wells are classified into four groups based on groundwater fluctuations and further into deep and shallow based on the depth to groundwater higher the fluctuations larger is its impact on groundwater chemistry actual seasonal patterns are identified using recharge discharge concept based on rainfall intensity instead of traditional monsoon non monsoon concept non pumped wells have low na cl and ca cl ratios in recharge period than in discharge period dilution few other wells which are subjected to pumping still exhibit dilution chemistry though water level fluctuations are high due to annual recharge other wells which do not receive sufficient rainfall and are constantly pumped showed high concentrations in recharge period rather than in discharge period anti dilution in summary recharge discharge concept demarcates the pumped wells from natural deep wells thus characterizing the basin

hydrogeochemistry of groundwater and anthropogenic control over dolomitization reactions in alluvial sediments of the deoria district ganga plain india groundwater is a critical resource in deoria district as it is the main source of drinking water and irrigation the aquifer has deteriorated to a high degree during the last two to three decades in quality and quantity due to high population growth and environmental pollution more than 90 of the population get their drinking water from subsurface waters fifteen wells were sampled in june 2006 to probe the hydrogeochemical components that influence the water quality the results show that groundwater have ec tds na mg2 hco 3 and th higher than the who 1997 maximum desirable limits a hydrogeochemical numerical model for carbonate minerals was constructed using the phreeqc package the regression analysis shows that there are three groups of elements which are significantly and positively correlated the main hydrochemical facies of the aquifer ca mg hco3 represents 33 33 of the total wells the geochemical modeling demonstrated that the reactions responsible for the hydrochemical evolution in the area fall into three categories 1 dissolution of salts 2 precipitation of dolomite 3 ion exchange solubility of dolomite calcite aragonite and gypsum were assessed in terms of the saturation index the thermodynamic prerequisites for dolomite supersaturation reactions are satisfied by subsurface waters since they are supersaturated with respect to dolomite undersaturated or in equilibrium with respect to calcite and undersaturated with respect to gypsum the ca2 versus so 4 2 and mg2 versus so 4 2 trends are also compatible with homologous trends resulting from dolomite supersaturation

a hydrogeological and hydrochemical explanation of the groundwater composition under irrigated land in a mediterranean environment algarve portugal in the campina de faro in the south of portugal agricultural practices have a large impact on groundwater composition these practices involve pumping of water for irrigation from combinations of large diameter shallow wells noras and small diameter deep boreholes furos excess irrigation water returns to the aquifer and mixes with water from the regional groundwater flow system this irrigation return flow is concentrated by strong evapotranspiration and by flushing of fertilisers the concentration increase induces cation exchange whereby ca on the soil exchanger is replaced by na the mixing in the aquifer allows application of a mixing cell model which may then be used to calculate transmissivities from the cl mass balance the calculations are complicated by the time variant behaviour of cl and the method is adjusted to calculate the change of chloride in time results from the calculations appear to be in good agreement with hydrochemical observations

estimation of weathering rates and co2 drawdown based on solute load significance of granulites and gneisses dominated weathering in the kaveri river basin southern india abstract the solute load of the kaveri river south india and its tributaries draining diverse precambrian terrains during pre monsoon and monsoon periods was determined using average annual flow total drainage area and atmospheric input corrected major ion concentrations of these rivers chemical weathering rates annual fluxes of different ionic species to the ocean and co2 consumption rates were estimated bicarbonate is the most dominant ion 27 79 of anion budget in all the river samples collected during monsoon period followed by ca2 whereas in case of pre monsoon water samples na is the most dominant ion in meq l two approaches were adopted to estimate silicate and carbonate weathering rates in the drainage basin at musuri silicate weathering rate swr is 9 44 0 29 tons km2 a and carbonate weathering rate cwr is 1 46 0 16 tons km2 a more than 90 of the total ionic budget is derived from weathering of silicates in the kaveri basin co2 consumption rate in the basin for silicate weathering f co 2 sil is 3 83 0 12 105 mol km2 a upper limit which is comparable with the himalayan rivers at upper reaches for carbonate weathering f co 2 carb co2 consumption rate is 0 15 0 03 105 mol km2 a in the kaveri basin the lower limit of co2 consumption rate corrected for h2so4 during silicate and carbonate weathering is f co 2 sil is 3 24 1005 mol km2 a and f co 2 carb 0 13 105 mol km2 a respectively co2 sequestered due to silicate weathering in the kaveri basin is 25 41 0 82 109 mol a which represents 0 21 0 01 of global co2 drawdown this may be due to tropical climatic condition high rainfall during both sw and ne monsoon and predominance of silicate rocks in the kaveri basin

dating large infrequent earthquakes by damaged cave deposits the long term recurrence patterns of past earthquakes are of considerable consequence for hazard assessments and have implications for earthquake physics we introduce a rigorously dated record of earthquakes from an extensive number of well preserved pre seismic and postseismic precipitates from caves located off the dead sea transform we dated events directly at the paleoseismic contact by means of a novel correlation method with the oxygen isotope record of the speleothems recovered in one of the caves within the 185 k y covered we dated 38 seismite samples these stem from 13 18 earthquakes with a mean recurrence interval of 10 14 k y we show that the deformational events dated in the study caves complement independent near fault paleoseismic records by tem poral correlation with the earthquakes recorded therein this opens up a significant new avenue of earthquake research that will provide precise dating and observational con straints on large infrequent earthquakes

inverse models to analyze the spatiotemporal variations of chemical weathering fluxes in a granito gneissic watershed mule hole south india water rock reactions are driven by the influx of water which are out of equilibrium with the mineral assemblage in the rock here a mass balance approach is adopted to quantify these reactions based on field experiments carried out in a granito gneissic small experimental watershed sew mule hole sew similar to 4 5 km 2 quartz oligoclase sericite epidote and chlorite are identified as the basic primary minerals while kaolinite goethite and smectite are identified as the secondary minerals observed groundwater chemistry is used to determine the weathering rates in terms of mass transfer coefficients mtcs of both primary and secondary minerals weathering rates for primary and secondary minerals are quantified in two steps in the first step top red soil is analyzed considering precipitation chemistry as initial phase and water chemistry of seepage flow as final phase in the second step minerals present in the saprolite layer are analyzed considering groundwater chemistry as the output phase weathering rates thus obtained are converted into weathering fluxes q weathering using the recharge quantity spatial variability in the mineralogy observed among the thirteen wells of mule hole sew is observed to be reflected in the mtc results and thus in the weathering fluxes weathering rates of the minerals in this silicate system varied from few 10 mu mol l in case of biotite to 1000 s of micromoles per liter calcite similarly fluxes of biotite are observed to be least 7 5 mol ha yr while those of calcite are highest 1265 791 mol ha yr further the fluxes determined annually for all the minerals are observed to be within the bandwidth of the standard deviation of these fluxes variations in these annual fluxes are indicating the variations in the precipitation hence the standard deviation indicated the temporal variations in the fluxes which might be due to the variations in the annual rainfall thus the methodology adopted defines an inverse way of determining weathering fluxes which mainly contribute to the groundwater concentration c 2011 elsevier b v all rights reserved

understanding groundwater systems and their functioning through the study of stable water isotopes in a hard rock aquifer maheshwaram watershed india summary groundwater degradation through abstraction contamination etc shows a world wide increase and has been of growing concern for the past decades in this light the stable isotopes of the water molecule 18 o and 2 h from a hard rock aquifer in the maheshwaram watershed andhra pradesh india were studied this small watershed 53 km 2 underlain by granite is endorheic and representative of agricultural land use in india with more than 700 bore wells in use in such a watershed the effect of overpumping can be severe and the environmental effects of water abstraction and contamination are of vital importance a detailed and dynamic understanding of groundwater sources and flow paths in this watershed thus is a major issue for both researchers and water managers especially with regards to water quality as well as the delimitation of resources and long term sustainability to this end the input from monsoon precipitation was monitored over two cycles as well as measuring spatial and temporal variations in 18 o and 2 h in the groundwater and in precipitation individual recharge from the two monsoon periods was identified leading to identification of periods during which evaporation affects groundwater quality through a higher concentration of salts and stable isotopes in the return flow such evaporation is further affected by land use rice paddies having the strongest evapotranspiration