geochemistry of cumulates from the bjerkreim sokndal layered intrusion s norway part ii ree and the trapped liquid fraction rare earth elements in bulk cumulates and in separated minerals plagioclase apatite ca poor and ca rich pyroxenes ilmenite and magnetite from the bjerkreim sokndal layered intrusion rogaland anorthosite province sw norway are investigated to better define the proportion of trapped liquid and its influence on bulk cumulate composition in leuconoritic rocks made up of plagioclase ca poor pyroxene ilmenite fmagnetite folivine where apatite is an intercumulus phase even a small fraction of trapped liquid significantly affects the ree pattern of the bulk cumulate together with cumulus minerals proportion and composition contrastingly in gabbronoritic cumulates characterized by the presence of cumulus ca rich pyroxene and apatite cumulus apatite buffers the ree content la sm and eu eu vs p2o5 variations in leuconorites display mixing trends between a pure adcumulate and the composition of the trapped liquid assumed to be similar to the parental magma assessment of the trapped liquid fraction in leuconorites ranges from 2 to 25 and is systematically higher in the north eastern part of the intrusion the likely reason for this wide range of tlf is different cooling rates in different parts of the intrusion depending on the distance to the gneissic margins the ree patterns of liquids in equilibrium with primitive cumulates are calculated with mass balance equations major elements modelling duchesne j c charlier b 2005 geochemistry of cumulates from the bjerkreim sokndal layered intrusion s norway part i constraints from major elements on the mechanism of cumulate formation and on the jotunite liquid line of descent lithos 83 299 254 permits calculation of the ree content of melt in equilibrium with gabbronorites partition coefficients for ree between cumulus minerals and a jotunitic liquid are then calculated calculated liquids from the most primitive cumulates are similar to a primitive jotunite representing the parental magma of the intrusion taking into account the trapped liquid fraction calculated from the p2o5 content consistent results demonstrate the reliability of liquid compositions calculated from bulk cumulates and confirm the hypothesis that the trapped liquid has crystallized as a closed system without subsequent mobility of ree in a migrating interstitial liquid d 2005 elsevier b v all rights reserved

recent seawater intrusion into deep aquifer determined by the radioactive noble gas isotopes 81kr and 39ar abstract radioactive noble gas isotopes tracers 81kr and 39ar are used for the first time to measure the residence times of deep 1000 m saline coastal groundwater and to determine its connection mode with the sea the average rate of seawater intrusion into the deep aquifer in israel located near the mediterranean sea is estimated 81kr ages of the saline water samples found to be younger than 40 ka contradict previously estimated ages of up to several million years based on hydrogeological considerations the new results imply a stronger and more recent connection between the aquifer and the sea and indicate that the intrusion occurred during the sea level rise that began about 20 ka ago these coastal aquifers need to be managed with caution because lowering of the adjacent fresh water level due to over pumping could accelerate seawater intrusion in a relatively short time this study demonstrates the suitability of these two noble gas tracers for the examination of hydrogeological systems in general and for the study of seawater intrusion in particular

water rock interactions and seawater freshwater mixing effects in the coastal dunes aquifer coos bay oregon abstract groundwater from the seawater freshwater interface in sandy sediments was sampled using a unique profile well designed in which separate pvc tube screens were installed at various depths all major ions except chloride showed non conservative behavior in the mixing zone so4 mg2 and k are depleted and hco3 is enriched relative to cl na is enriched in solutions containing less than 20 seawater and depleted in solutions containing higher percentages of seawater the behavior of ca2 is the mirror image ofthat of na the chemical data on the stratification of groundwater above and within the interface zone were obtained using a unique profile well design in which separate pvc tube screens were installed at various depths thus making it possible to extract water samples at close vertical intervals the chemical changes in the groundwater reflect the following processes 1 a ca2 na and ca2 mg2 base exchange reactions 2 b oxidation of organic matter in the sediment 3 c reduction of sulfate probably due to bacterial processes 4 d reaction of hco3 and s2 with fe2 to produce mineral coatings and cements of pyrite and siderite 5 e k feldspar formation producing lower of k concentrations the authigenic phases were identified using scanning electron microscopy thermodynamic calculations suggest that all solutions are saturated with respect to quartz and chalcedony and many are saturated with respect to calcite dolomite siderite and hematite kaolinite is the stable clay mineral in the top of the freshwater column whereas smectite is the stable clay mineral in the lower part of the freshwater column and in the seawater freshwater mixing zone

the kraemer island macrodyke east greenland solidification of a flood basalt conduit the kraemer island macrodyke that is exclusively exposed on kraemer island about 7 km west of the skaergaard intrusion belongs to a regional dyke swarm termed the skaergaard like dykes or fg 1 dykes weakly modally layered olivine gabbros dominate the exposed parts of the intrusion that has a width of 650 m to 1000 m plagioclase core an 68 2 and ca rich pyroxene core mg no 79 1 grains are normally zoned whereas olivine grains fo50 65 are homogeneous calculated mineral magma equilibria based on experimentally determined mg fe magma olivine and magma clinopyroxene partition coeffi cients suggest that the observed olivine and clinopyroxene compositions in the gabbros cannot have formed from a common parental magma the unzoned nature of olivine grains and their iron rich com positions relative to clinopyroxene suggest post cumulus mg fe exchange between olivine and interstitial melt a gabbroic pegmatite is developed in the centre of the intrusion along its entire exposed 5 km strike length here mineral zonation is limited and compositions are similar to rims of cumulus minerals in the enveloping olivine gabbros the pegmatite could therefore represent interstitial melt mobilized from gab broic cumulates that later accumulated and crystallized at its present stratigraphic location cumulus olivines in the gabbros are close to equilibrium with ca rich pyroxene in the pegmatite this is interpreted as reflecting interstitial melt mobility during the late stages of solidification of the macrodyke chilled margins are well preserved at the intrusion margins and are rich in fe 14 15 3 feo tot ti 3 3 3 tio2 and light rare earth elements la sm n 1 2 1 3 similar to magmas well represented in the overly ing sequence of contemporaneous high ti series flood basalts it is therefore likely that extensive wall rock melting adjacent to the macrodyke reflects continuous feeding of the overlying flood basalts through the kraemer island macrodyke

a multi isotope b sr o h and c and age dating 3h 3he and 14c study of groundwater from salinas valley california hydrochemistry dynamics and contamination processes 1 the chemical and isotope 11b 10b 87sr 86sr 18o 16o 2h h 13c 12c 14c and 3he 3h compositions of groundwater from the upper aquifer system of the salinas valley in coastal central california were investigated in order to delineate the origin and processes of groundwater contamination in this complex system the salinas valley has a relatively deep confined 400 foot aquifer overlain by a 180 foot aquifer and a shallower perched aquifer all made up of alluvial sand gravel and clay deposits groundwater from the aquifers have different 14c ages fossil 14c 21 3 percent modern carbon pmc for the 400 foot aquifer and modern 14c 72 2 98 2 pmc for the 180 foot aquifer fresh groundwater in all aquifers is recharged naturally and artificially through the salinas river the two modes of recharge can be distinguished chemically we identified several different saline components with distinguishable chemical and isotopic fingerprints 1 saltwater intrusion in the northern basin has c1 concentrations up to 1700 mg l a na cl ratio less than seawater a marine br cl ratio a ca cl ratio greater than seawater 11b between 17 and 38 and 87sr 86sr between 0 7088 and 0 7096 excess dissolved ca relative to the expected concentration for simple dilution of seawater correlates with 87sr 86sr ratios suggesting base exchange reaction with clay materials 2 agriculture return flow is high in no3 and so4 with a 87sr 86sr 0 7082 11b 19 and 13c between 23 and 17 the 3h 3he ages 5 17 years and 14c data suggest vertical infiltration rates of irrigation water of 3 10 m yr 3 nonmarine saline water in the southern part of the valley has high total dissolved solids up to 3800 mg l high so4 na cl ratio 1 11b between 24 and 30 and 87sr 86sr 0 70852 this groundwater may have acquired its geochemical signature from leaching of sedimentary rocks associated with the coast range marine deposits of mesozoic to early cenozoic age the combination of different geochemical and isotopic fingerprints enables us to delineate the impact of salt sources in different areas of the valley and to reconstruct the origin of the so4 enriched no3 depleted saline plume that is located west of the city of salinas we suggest that the latter is derived from a mixture of different natural saline waters rather than from anthropogenic contamination

petrology of the treknattan intrusion in the fongen hyllingen complex trondheim region norway a late intrusion into an evolved layered complex abstract the basic ultrabasic treknattan intrusion is an important example of a late intrusion in a solidified evolved layered complex and sheds light on possible mechanisms by which such associations may develop the treknattan intrusion emplaced into the basic fongen hyllingen intrusion shortly after the latter had solidified consists mainly of massive or weakly layered peridotite olivine cr spinel cumulate and troctolite plagioclase olivine cr spinel cumulate the mineral compositional range partially overlaps the most primitive end of the much larger variation interval in the fongen hyllingen intrusion the margin of the treknattan intrusion is sometimes outlined by massive feldspathic websterite which appears to have formed by reaction between magma and melts of gabbroic country rock the parental magma appears to have been a relatively water rich picritic basalt with a possible genetic relationship to the magma parental to the enveloping fongen hyllingen intrusion both displaying tholeiitic relationship between olivine and ca poor pyroxene and having crystallized from relatively water rich magmas with an early crystallization order of olivine cr spinel plagioclase ca rich pyroxene the recognition of the treknattan intrusion as a separate body suggests that the bulk composition of the fongen hyllingen intrusion is dioritic rather than gabbroic as previously thought

a numerical solution for the movement of an interface in a layered coastal aquifer abstract this paper deals with seawater intrusion in a coastal aquifer where close to the coast the aquifer is divided into a number of subaquifers by impervious relatively thin layers as a result of changing the total fresh water discharge to the sea seawater intrusion occurs as a separate advancing wedge in each of the subaquifers assuming everywhere flow normal to the coast line and essentially horizontal in both the fresh water and the salt water zones the complete mathematical model is first stated in terms of depth to the interface in each subaquifer a numerical finite difference scheme is then presented for solving the model for the case of a two layered aquifer principles of a method for extending the model to a larger number of subaquifers is described

demarcating saline water intrusion pathways using remote sensing gis and geophysical techniques in structurally controlled coastal aquifers in southern india application of remote sensing and geographical information system gis with the help of ground truth studies like vertical electrical soundings ves and water quality measurements gave a comprehensive picture on saline water intrusion pathways in the structural controlled aquifers of uppanar and cauvery river systems located in sirkazhi and mannanpandal coastal areas of southern india the detailed geomorphic units and lineaments were mapped using irs liss iii 1 50 000 scale and srtm elevation digital data under gis environment the area is mainly alluvial deposits of holocene age and classified into three major geomorphic units i e fluvial fluviomarine and marine geomorphic units the identified lineaments are mostly trending north northeast nne south southwest ssw northeast ne southwest sw northwest nw southeast se east west ew and east northeast ene west southwest wsw directions some of them are potential for fresh groundwater occurrence and movement the lineaments trending ne sw nne ssw and ene wsw act as pathways for saline water intrusion to the inland the lineament l1 nne ssw trending conformed as a sinisterly shifted fault played a significant role in saline water intrusion the area within the parallel lineaments l2 and l3 oriented ene wsw direction indicates low topography beach ridges paleo channel sinuosity large aerial extent of tidal flats and backwater inundation all the above geomorphic units gave indirect evidence of land subsidence which was confirmed with the help of sub surface geo electrical signals obtained through ves and in situ groundwater quality measurements integrating all the above results the saline water spread and fresh water pockets were identified

water rock interactions in a modern coastal mixing zone the chemical evolution of ground water and the diagenetic history of the rocks in a modern saline fresh water mixing zone were investigated to test the hypothesis that this zone is a chemically active environment in which carbonate mineral diagenesis occurs the field site was in the unconfined section of the upper floridan aquifer system in west central florida a regionally extensive hydrostratigraphic unit composed of eocene oligocene limestone and dolomite the mixing zone marked by a steep concentration gradient is 90 m thick at the study site in new port richey pasco county florida interpretation of aqueous geochemical data indicates that the coastal zone is most likely a location where three waters of distinct composition mix a fresh ca hco3 water that derives its composition from calcite dissolution and co2 influx in the up gradient recharge area a na cl water that results from salt water intrusion and a ca so4 rich water that upwells subsequent to contact with underlying gypsiferous beds of the avon park formation are likely all converging in this coastal setting poor core recovery and an enlarged core hole provide evidence of dissolution the ground water however is oversaturated with respect to calcite thus the large scale dissolution features observed are unrelated to modern day mixing the mixing of ca so4 rich ground water in the coastal region led to oversaturation with respect to calcite at the petrographic scale there is little evidence of diagenesis related to the modern mixing zone calcite crystals from the lower section of the cored interval have isotopic signatures that are different than those from the upper section suggesting that the latter has undergone more water rock interactions calcium rich dolomite which occurred relatively late in the paragenetic sequence has thin cathodoluminescent zonations but shows no evidence of subsequent alteration the paragenetic sequence includes marine micritization and cementation meteoric mineralogic stabilization dissolution enhancement of porosity phreatic equant calcite cements and echinoderm overgrowths all typical of the region and not unique to the mixing zone

reconciliation of late quaternary sea levels derived from coral terraces at huon peninsula with deep sea oxygen isotope records a major discrepancy between the late quaternary sea level changes derived from raised coral reef terraces at the huon peninsula in papua new guinea and from oxygen isotopes in deep sea cores is resolved the two methods agree closely from 120 ka to 80 ka and from 20 ka to 0 ka ka 1000 yr before present but between 70 and 30 ka the isotopic sea levels are 20 40 m lower than the huon peninsula sea levels derived in earlier studies new high precision u series age measurements and revised stratigraphic data for huon peninsula terraces aged between 30 and 70 ka now give similar sea levels to those based on deep sea oxygen isotope data planktonic and benthic 18o data using the sea level and deep sea isotopic data oxygen isotope ratios are calculated for the northern continental ice sheets through the last glacial cycle and are consistent with results from greenland ice cores the record of ice volume changes through the last glacial cycle now appears to be reasonably complete

differential dissolution of a pleistocene reef in the ground water mixing zone of coastal yucatan mexico a geochemical explanation is provided for the extensive dissolution observed along the carbonate coast of the yucatan peninsula mexico mixing of fresh ground water with subterranean caribbean seawater generates a highly reactive geochemical zone that enhances aragonite and calcite dissolution and permits neomorphism of aragonite mixing zone dissolution caused by ground water discharge is a major geomorphic process in developing caves coves and crescent shaped beaches along the yucatan coast such dissolution has probably been a significant control on permeability and porosity distribution in carbonate rocks in the geologic record

isotopic and geochemical characterization of salinization in the shallow aquifers of a reclaimed subsiding zone the southern venice lagoon coastland summary the coastal plain bordering the southern venice lagoon is a reclaimed lowland characterized by high subsidence rate and ground level and water table depth below sea level in this agricultural region where the surface hydrologic network is entirely artificially controlled by irrigation drainage canals salinization problems have long been encountered in soils and groundwaters here we use isotopic and geochemical tracers to improve our understanding of the origin of salinization and mineralization of the semi confined aquifer 0 40 m and the freshwater inputs to this hydrological system water samples have been collected at different seasons in the coastal adriatic sea lagoon rivers and irrigation canals as well as in the semi confined aquifer at depths between 12 and 35 m 14 boreholes and in the first confined aquifer three boreholes drilled between 40 and 80 m depth stable isotopes 18 o and d and conductivity profiles show that direct saline intrusion from the sea or the lagoon is observed only in a restricted coastal strip while brackish groundwaters are found over the entire topographic and piezometric depression in the centre of the study area fresh groundwaters are found only in the most western zone the sharp isotopic contrast between the western and central regions suggests disconnected hydrological circulations between these two parts of the shallow aquifer the border between these two regions also corresponds to the limits of the most strongly subsiding zone our results can be interpreted in terms of a four end member mixing scheme involving 1 marine water from the lagoon or the open sea 2 alpine and pre alpine regional recharge waters carried either by the main rivers adige bacchiglione and brenta irrigation waters or by the regional groundwater circulation 3 local precipitation and 4 evaporated waters infiltrated from the surface infiltration from the surface is also revealed by the stratification of the electrical conductivity profiles showing that the brackish groundwaters are overlain by a shallow layer of less saline water all over the central depression in the first confined aquifer the groundwaters have isotopic compositions similar to the deep groundwaters of the venetian confined aquifers 40 400 m depth the isotopic data and the br cl ratio show that the origin of the salinization of the phreatic aquifer can be ascribed to seawater intrusion alone with no indication of the involvement of deep brines identified at 450 m depth in the process the chemical composition of the saline and brackish groundwaters is characterized by an excess of sodium and a deficit of calcium compared to conservative mixing between fresh groundwaters and seawater this suggests that the phreatic aquifer is progressively freshening as a consequence of the beneficial influence of the extensive irrigation drainage network including raised canals acting as a hydraulic barrier along the coast this freshening tendency may have been lasting since the reclamation in the mid twentieth century and has probably been accelerated by the ban on groundwater abstraction since the 1970s

the distribution of platinum group elements in the insizwa lobe mount ayliff complex south africa implications for ni cu pge sulfide exploration in the karoo igneous province the mount ayliff complex of the eastern cape province of south africa is a layered intrusion of some 800 km2 surface area and up to 1 200 m thickness on the basis of compositional similarities and spatial association it is generally interpreted to form part of the karoo igneous province similarities between the mount ayliff complex and the staging chambers and feeder conduits to flood basalts that host magmatic sulfide ores elsewhere in the world suggest that the mount ayliff complex may have an enhanced potential for noril sk talnakh type massive ni cu sulfide ores an idea that is supported by the well known sulfide occurrence at waterfall gorge here we present major trace and noble element data for 30 samples of cumulate rocks from a continuous 1 200 m drill core through the insizwa lobe of the complex as well as six samples of a footwall sill the taylor s koppie dike that was considered a possible feeder zone to the lobe and through a massive sulfide lens in the footwall of the lobe at ndzongiseni we show that most of the insizwa cumulate rocks contain small amounts of cumulus sulfides the sulfides including those at waterfall gorge can be explained by a model in which the sulfides were segregated from magma having chilled margin composition on the basis of the composition of the chilled margins the insizwa magma contained no entrained sulfides and was depleted in platinum group elements pge although not in cu and ni before emplacement these compositional characteristics are also observed in lavas of the central karoo igneous province and suggest only limited sulfide segregation from these magmas at depth our findings thus indicate relatively little potential for economic magmatic ni cu pge sulfide deposits in the insizwa lobe

rock magnetic stratigraphy of a mafic layered sill a key to the karoo volcanics plumbing system abstract the insizwa sill is an 1 km thick subhorizontal layered mafic intrusion and part of the karoo large igneous province in south africa this well exposed intrusion consists of several superimposed petrologically and geochemically distinct units magnetic methods were used to study the intrusion in order to constrain the physical processes active in these types of bodies during crystallization rock magnetism studies indicate that within different petrologic units bulk susceptibility is controlled by primary magnetite with minor pyrrhotite and or paramagnetic minerals olivine pyroxene new magnetic data based on 659 specimens obtained from 3 vertical borehole cores each spaced 5 km apart confirm the prominent vertical zonation in low field magnetic susceptibility k lf degree of anisotropy p j and orientation of the anisotropy of magnetic susceptibility ams axes the magnetic susceptibility correlates very well with petrographic units and the lateral continuity of magnetic units between boreholes is very consistent petrologic units with high but variable k lf also show moderate anisotropy and dominantly vertical foliations we interpret these patterns to result from inverse fabrics from single domain magnetite the degree of anisotropy is low in petrologic units with low k lf which also show shallowly dipping magnetic foliations we interpret that the magnetic properties of these units are dominated by the paramagnetic minerals these low k lf petrologic units also show no systematic increase in k lf suggesting that only minor differentiation is occurring in these units the dataset derived from 2 surface sampling traverses are consistent with borehole core ams data showing a pattern of dominantly steep magnetic foliation and variably plunging magnetic lineation with a nw se trend

zoned orthopyroxenes in the ni co sulfide ore bearing xiarihamu mafic ultramafic intrusion in northern tibetan plateau china implications for multiple magma replenishments abstract the xiarihamu mafic ultramafic intrusion is situated in the east kunlun orogenic belt e kob northern tibetan plateau china with ni co sulfide mineralization mainly in orthopyroxenite and olivine orthopyroxenite whole rock and mineral compositions show cyclic variations in drill hole intersections through the xiarihamu mafic ultramafic intrusion microbeam x ray fluorescence xrf mapping shows reverse zoning cr poor core cr rich rim and oscillatory zoning cr poor core cr rich mantle and cr poor rim in orthopyroxene of olivine orthopyroxenite and orthopyroxenite zoned orthopyroxenes are euhedral or subhedral and there are relatively sharp interfaces between zones with distinct cr contents crystal size distribution csd curves of orthopyroxenes in olivine orthopyroxenite show concave upward curvature at size larger than 3 0 mm and larger orthopyroxenes commonly display zoning implying a secondary recrystallization and grain growth of larger orthopyroxenes quantitative analyses show that cr and enstatite contents of cores are relatively lower but incompatible element e g ti zr ga and sr contents of cores are higher than rims in reverse zoned orthopyroxenes and chemical profiles of unzoned orthopyroxenes resemble those of rims but different from those of cores in reverse zoned orthopyroxenes chemical profiles of orthopyroxenes indicate that cr zoning is not due to the change in cr partitioning behavior between orthopyroxene and silicate melt which shows significant temperature and redox dependence textural feature and crystal size distribution of orthopyroxenes suggest the formation of cr rich zones attests to the multi stage growth in the process of magma replenishment rather than a reactive liquid flow model or in situ trapped liquid overgrowth orthopyroxene zoning together with compositional variation and intrusive relationship between olivine orthopyroxenite and orthopyroxenite imply that the xiarihamu mafic ultramafic intrusion was formed by multiple magma replenishments with magma varying roughly from a more evolved to a more primitive composition

aquifer vulnerability and seawater intrusion risk using galdit gqiswi and gis case of a coastal aquifer in tunisia due to increase in population and agricultural activities the sfax coastal aquifer is under tremendous stress and seawater intrusion becomes a serious concern this situation needs an assessment of aquifer vulnerability and seawater intrusion risk a new approach for vulnerability mapping using galdit groundwater quality index for seawater intrusion gqiswi geostatistics the ghyben herzberg model and gis was developed the model is used to determine the trend of groundwater contamination by seawater intrusion in the coastal aquifer in sfax basin tunisia vulnerability assessment method is recognized through assessing weight and ratings of the galdit relevant parameter a second vulnerability map was realized based upon the groundwater quality index for seawater intrusion integrating the water quality parameters for delineating seawater intrusion in the aquifer the validation of gqiswi and galdit vulnerability maps was undertaken through comparison of areas of high jones ratio chloride and tds concentration and their relative vulnerability index the ghyben herzberg model has been used to predict the actual seawater intrusion extend and evaluate the freshwater saltwater dynamics the results reveal that the coastal area is currently undergoing seawater intrusion and its northern part is the most affected one by this contamination

groundwater ages and reaction rates during seawater circulation in the dead sea aquifer the dead sea system provides a unique opportunity to study flow velocities and reaction rates during seawater circulation in the aquifer we present here a novel application of calculating groundwater age and velocity along the flow path of the hypersaline water from the dead sea into the aquifer using the buildup rate of 228 ra in this water the calculated circulation velocities are 1 10 m y which is in agreement with estimates based on the na cl ratios in this water 1 5 4 m y the latter is unique to the dead sea aquifer system where the na cl ratio has been decreasing during the past 50 years due to the precipitation of halite in the lake the velocity estimates facilitated the calculation of the rates of water rock interactions in the dead sea aquifer

regional hydrogeochemistry of a modern coastal mixing zone in west central florida groundwater samples were collected along flow paths in the unconfined upper floridan aquifer that cross the inland freshwater recharge area and the coastal discharge area a groundwater flow and solute transport model was used to evaluate groundwater flow and mixing of fresh and saline groundwater along a cross section of the unconfined upper floridan aquifer results show that between 8 and 15 of the fresh and 30 31 of the saline groundwater penetrates to the depth in the flow system where contact with and dissolution of gypsum is likely the deeply circulating fresh and saline groundwater returns to the near surface environment discharging caso4 rich water to the coastal area where it mixes with fresh cahco3 groundwater resulting in a prediction of calcite precipitation in the modern mixing zone

a grenville age layered intrusion in the subsurface of west texas petrology petrography and possible tectonic setting the nellie intrusion is a thick more than 4420 m mafic to ultramafic layered intrusion with a radiometric age of 1163 ma rock types change abruptly with stratigraphic height and include norite pyroxenite gabbronorite hornblende gabbro gabbro anorthosite harzburgite and lherzolite norite is most abundant but gabbro and hornblende gabbro are locally abundant rare olivine rich layers are also present the general order of crystallization was olivine orthopyroxene plagioclase clinopyroxene and hornblende mg s expressed as 100 mg mg fe range from 76 3 to 85 8 for olivine 56 7 to 84 9 for orthopyroxene 62 5 to 90 3 for clinopyroxene and 52 4 to 82 8 for amphibole mg s vary with height and display abrupt reversals which indicate open system addition of new mafic magma eleven cyclic units were identified on the basis of evidence for injection of basaltic magma these can be grouped into three megacyclic units the abundance of orthopyroxene and mineral compositional evidence for

reequilibration of olivine with trapped liquid in the duluth complex minnesota a 525 m long drill core ddh 221 through the partridge river intrusion in northeastern minnesota consists of mesocumulates and or orthocumulates of troctolite olivine gabbro and olivine gabbronorite the cumulus olivine whose composition fo 31 to fo 71 is a function of the amount of intercumulus liquid followed an equilibrium crystallization path with this liquid estimates of the primary magmatic compositions of the olivine are fo 57 to fo 79 none of the olivine in the drill core samples has retained an original cumulus composition i e one that was in equilibrium with the parental magma the plagioclase is strongly zoned and the cumulus cores an 59 to an 73 are thought to record crystallization from the parental magma

macrorhythmically layered gabbronorites in the windimurra gabbroid complex western australia abstract plagioclase orthopyroxene augite cumulates gabbronorites in the 3 5 km thick wagoo hills section show strong rhythmic modal layering over about 200 m of section layers of mafic gabbronorite mgn 1 10 m thick alternate with leucogabbronorite lgn 10 5 m thick with sharp contacts mgn are adcumulates with 65 70 plagioclase cores an68 reverse zoning 20 orthopyroxene mg69 15 augite mg78 and whole rock mg number 65 in contrast lgn are mesocumulates more orthocumulate character with 80 90 plagioclase cores an75 normal zoning 6 augite mg71 4 orthopyroxene mg62 and whole rock compositions have mg numbers ca 54 and higher concentrations of incompatible elements e g k p and lower concentrations of compatible elements and pge than in mgn lgn contain minor interstitial postcumulus quartz hornblende fe ti oxides apatite and 5 25 hydrous alteration products unlike mgn the cause of the presumed cumulus stage differences in pyroxene plagioclase modal ratio noncotectic proportions in lgn and sharp mgn lgn mgn contacts is not clear but could result from rhythmic variations in supercooling and nucleation the postcumulus differences postcumulus mineralogy normal zoned plagioclase more fe rich pyroxenes and higher incompatibles in lgn are interpreted in terms of an in situ crystallisation compositional convection model cumulus mineral assemblages in mgn have a higher fractionation density and their in situ crystallisation released a buoyant residual liquid which was continuously displaced by fresher magma resulting in only 0 5 residual liquid trapped with the mush adcumulate formation in contrast in situ crystallisation of a plagioclase rich cumulus assemblage lower fractionation density in lgn resulted in a denser stagnant residual liquid 10 15 of which was trapped in the crystal mush producing normal zoning in plagioclase 6 8 atom fe shift in pyroxene compositions and higher incompatible element concentrations and h 2 o the latter resulting in selective alteration of lgn as a result mgn had higher solidus t and acted like seals or aquicludes whereas lgn had lower solidus t and were sinks or aquifers for incompatibles and volatiles

tide induced fluctuations of salinity and groundwater level in unconfined aquifers field measurements and numerical model the responses of the fresh saline water interface fsi and the groundwater level gwl to the mediterranean sea tide were monitored in the coastal aquifer of israel modeled numerically and analyzed using cross correlation analysis different time lags between sea level fluctuations and hydraulic head and salinity fluctuations were detected for the fsi and the gwl at the fsi the time lag of hydraulic head behind the sea level is much shorter than the lag of the salinity at the same point surprisingly similar time lags behind the sea level were measured for both the hydraulic head at the gwl and the salinity at the fsi both at the same distance from the shoreline results from a numerical model simulating the flow and transport processes at the field scale agree with field measurements in both the gwl and the salinity in the fsi fluctuate almost simultaneously while the hydraulic head in the fsi reacts faster to sea level fluctuations the actual movement of the fresh water body which is controlled by the unsaturated flow in the capillary fringe capillary effect lags behind the pressure head fluctuations in the deeper parts of the aquifer which is controlled by saturated parameters of the aquifer the overall results agree with the conceptual mechanism suggested by levanon et al 2016 in which the effect of sea tide on the coastal groundwater system comprises two main processes 1 tidal fluctuations at the sea floor boundary which cause pressure wave propagation into the aquifer and 2 attenuation at the gwl due to the capillary effect which control also the change in the salinity and the actual movement of the fsi

contrasting petrological and geochemical relationships in the voisey s bay and mushuau intrusions labrador canada implications for ore genesis new data on the voisey s bay and mushuau intrusions indicate that the two bodies which were formerly grouped as the reid brook complex differ markedly in age petrology geochemistry and the scale of known mineralization u pb dating of baddeleyite and zircon has revealed that the mushuau intrusion has an age of 1 313 ga which is 20 m y younger than the 1 333 ga voisey s bay intrusion the voisey s bay intrusion is host to the 124 million tons ni cu co sulfide deposit reserves resources mineralization occurs at the base of an upper subchamber the eastern deeps subchamber and in a conduit that connects the eastern deeps to a lower subchamber the reid brook subchamber the mineralization is associated with a basal breccia that contains abundant reacted inclusions of paragneiss within the eastern deeps the basal mineralization is overlain by a varied textured troctolite that contains variable amounts of disseminated sulfide and gneiss inclusions by comparison only minor amounts of sulfide mineralization have been observed within the mushuau intrusion the mushuau intrusion comprises a layered unit that has been intruded by a stellate textured troctolite along its contact with footwall orthogneiss the layered unit consists dominantly of melatroctolite at the margin with leucotroctolite toward the center and olivine gabbro at the core the cumulates of the mushuau intrusion are richer in olivine and thus have higher mgo contents than those of the voisey s bay intrusion notwithstanding this olivines in the melatroctolite inclusions of the voisey s bay intrusion which are thought to represent disrupted cumulus layers contain up to 81 mole percent forsterite whereas those in the melatroctolite of the mushuau intrusion contain no more than 70 mole percent forsterite nickel depletion in olivine is more pronounced in the voisey s bay intrusion than in the mushuau intrusion our data indicate that the parental magmas of both intrusions were broadly basaltic mgo 8 1 wt and that the magma of the mushuau intrusion was more evolved than that of the voisey s bay intrusion yet still capable of forming olivine rich cumulates the troctolites of the voisey s bay intrusion have ce yb 22 to 27 whereas most troctolites of the mushuau intrusion have ce yb 12 to 17 the rocks of the mushuau intrusion are simple mixtures of mantle derived magma and local orthogneiss whereas the rocks of the voisey s bay intrusion are formed by multiple stages of crustal contamination including an early stage of contamination at lower midcrustal level and a late stage of contamination by tasiuyak paragneiss at upper crustal level the assimilation of the sulfide bearing tasiuyak paragneiss by magma at voisey s bay may have promoted initial sulfide saturation and or increased sulfide oversaturation thus contributing to the segregation of large amounts of sulfide liquid from magma continuing flow of magma through a dynamic conduit system at voisey s bay has caused the local accumulation of sulfide of sufficient size and grade to constitute mineable reserves

processes affecting groundwater chemistry in a zone of saline intrusion into an urban sandstone aquifer abstract samples have been collected from inflows into railway tunnels in the triassic sandstone aquifer beneath liverpool and the mersey estuary england u k these provide a profile through a saline freshwater mixing zone analyses were made of major anions and cations 34s and 18o in so4 13c in dissolved inorganic c and 87sr 86sr the data demonstrate that the presence of a low permeability fault exerts a strong control on the local groundwater chemistry on the estuary side of the fault groundwater chemistry is dominated by mixing of intruding estuary water which is modified by so4 reduction and calcite dissolution with fresh groundwater the environment of so4 reduction in the tidal estuary is one of repeated reduction and re oxidation of s in an open system and has resulted in virtually no change in s isotopic composition but an enrichment in residual so4 18o of 1 5 groundwater chemistry on the landward side of the fault is primarily the result of recharge in an urban environment there is also evidence that saline water has been present in this region of the aquifer in the past and that this has now been flushed by fresh groundwaters this saline water was either transported along the landward side of the fault from nearer the estuary or more probably transmitted across the fault both mechanisms would have been driven by large landward head gradients caused by heavy industrial abstraction earlier this century this has produced a zone of groundwaters depleted in ca and radiogenic sr and enriched in na as a result of ion exchange between the fresh groundwaters and the aquifer previously occupied by more saline water sulphur isotopic composition however shows no variation since so4 does not undergo significant ion exchange a tracer test from a borehole to the tunnels showed multiple breakthroughs to some locations indicating a number of different flow paths through the aquifer the maximum flow velocity recorded in this test was 140 m d suggesting flow along fractures

hydrogeochemistry of grand cayman british west indies implications for carbonate diagenetic studies abstract groundwater in the dolostone aquifers of the bluff group oligocene miocene on grand cayman is divided into fresh lightly and highly brackish and saline type i and ii zones according to chemical characteristics that were determined during a 3 year 1985 1988 monitoring program brackish and type i saline waters display the greatest variation in chemical properties whereas the type ii saline water has the most stable chemical characteristics most groundwaters from these dolostone aquifers are thermodynamically capable of precipitating calcite and or dolomite the saturation indices for these minerals however vary through time and space even in the context of small water lens simple mixing of fresh and sea water cannot explain the chemistry of the water found in the joint and karst controlled dolostone aquifers of grand cayman deviation from a simple mixing model is due to variations caused by tidal fluctuation the rate of rain water recharge influx of ca rich groundwater from the surrounding limestone aquifers influx of co 2 rich surface water from sinkholes and swamps and water rock interactions dissolution and precipitation of calcite and dolomite sustained groundwater abstraction from a lens can significantly alter the hydrochemistry of the water lens this suggests that hydrochemical characterization of small fresh water lenses like those on grand cayman cannot be based on spot or short term sampling interpretation of such fluids in terms of calcite dolomite precipitation and or dissolution must be treated with caution if the data base has not been derived from long term monitoring

large scale magmatic layering in the main zone of the bushveld complex and episodic downward magma infiltration the bellevue drillcore intersects 3 km of main and upper zone cumulates in the northern limb of the bushveld complex main zone cumulates are predominately gabbronorites with localized layers of pyroxenite and anorthosite some previous workers using bulk rock major trace and isotopic compositions have suggested that the main zone crystallized predominantly from a single pulse of magma however density measurements throughout the bellevue drillcore reveal intervals that show up section increases in bulk rock density which are difficult to explain by crystallization from a single batch of magma wavelet analysis of the density data suggests that these intervals occur on length scales of 40 to 170 m thus defining a scale of layering not previously described in the bushveld complex upward increases in density in the main zone correspond to upward increases in modal pyroxene producing intervals that grade from a basal anorthosite with 5 pyroxene to gabbronorite with 30 40 pyroxene we examined the textures and mineral compositions of a 40 m thick interval showing upwardly increasing density to establish how this type of layering formed plagioclase generally forms euhedral laths while orthopyroxene is interstitial in texture and commonly envelops finer grained and embayed plagioclase grains minor interstitial clinopyroxene was the final phase to crystallize from the magma plagioclase compositions show negligible change up section average an62 with local reverse zoning at the rims of cumulus laths average increase of 2 mol in contrast interstitial orthopyroxene compositions become more primitive up section from mg 57 to mg 63 clinopyroxene similarly shows an up section increase in mg pyroxene compositions record the primary magmatic signature of the melt at the time of crystallization and are not an artefact of the trapped liquid shift effect combined the textures and decoupled mineral compositions indicate that the upward density increase is produced by the downward infiltration of noritic magma into a previously emplaced plagioclase rich crystal mush fresh noritic magma soaked down into the crystallizing anorthositic mush partially dissolving plagioclase laths and assimilating fe enriched pore melt the presence of multiple cycles showing upward increases in density in the bellevue drillcore suggests that downward magma infiltration occurred episodically during crystallization of the main zone

occurrence and mobilization of radium in fresh to saline coastal groundwater inferred from geochemical and isotopic tracers sr s o h ra rn abstract salinization in groundwater systems can induce water rock interaction including the release of naturally occurring trace elements of health significance such as radium ra with possible implications for the usability of water resources in addition to the increase of dissolved solids tds concentrations in general radium mobility is limited by chemical removal mechanisms including adsorption onto clays and or mn and fe oxides exchange processes and coprecipitation with secondary barite in order to examine the effect of aquifer salinity gradients on the distribution of naturally occurring ra in fresh to saline groundwater and the relationship to water rock interaction and ra removal mechanisms two contrasting systems were investigated the shallow unconfined coastal aquifer in agadir southwestern morocco and the confined cretaceous cape fear and pliocene yorktown aquifers of the atlantic coastal plain north carolina usa geochemical and isotopic indicators of salinity sources e g cation ratios 18o 2h br cl 34 s so 4 2 18 o so 4 2 were used to identify the relative contributions of seawater and other saline waters and subsequent geochemical modification by water rock interaction radium activities 224ra 226ra 228ra radon 222 alkaline earth metal mg ca sr ba concentrations and ratios and 87sr 86sr ratios were analyzed to identify water rock interaction processes affecting alkaline earth metals including ra the morocco coastal aquifer is generally oxic exhibits a range of salinity and water types cl 163 2120 mg l median 932 mg l and exhibits ca na ratios above the seawater value typical of monovalent divalent cation exchange base exchange reactions in coastal aquifers in contrast the atlantic coastal plain aquifers are anoxic sulfate reducing cover a wider salinity range cl 5 9890 mg l median 800 mg l representing a transition between na hco 3 and na cl waters and exhibit ca na ratios below that of modern seawater typical of reverse base exchange reactions possible salinity sources in the morocco coastal aquifer include seawater intrusion mesozoic evaporites other natural saline waters and or wastewater whereas the atlantic coastal plain is primarily affected by old seawater present in the aquifer system radium activities are generally low and vary significantly within each aquifer for example 226ra ranges from 1 8 27 7 mbq l in the morocco coastal aquifer median 8 1 mbq l and 1 9 214 mbq l in the atlantic coastal plain median 18 9 mbq l the highest ra activities were observed in the most saline wells sampled in the atlantic coastal plain at total dissolved solids tds concentrations above an apparent threshold of 5000 mg l radium activities increase in a generally linear fashion with salinity in the atlantic coastal plain broadly comparable to previous studies indicating a threshold range of 3000 10 000 mg l at lower tds concentrations water rock interaction processes that vary with local aquifer conditions appear to control ra distribution rather than merely salinity in the morocco coastal aquifer adsorption of ra and coprecipitation with secondary barite are apparently favorable to control ra levels in groundwater radium removal in the anoxic atlantic coastal plain aquifers appears to be associated with adsorption and or exchange processes with the additional possibility of barite precipitation in the cape fear aquifer indicated by barite saturation overall the locally variable factors that can control ra sources and mobility in fresh to brackish groundwater at near neutral ph include variation in solid phase radioactivity redox state affecting adsorption sites availability of competing divalent cations and barite saturation

hydrogeochemical characteristics in coastal groundwater mixing zone abstract this study presents the hydrogeochemical analysis in coastal groundwater mixing zone of a sandy aquifer ting kok hong kong groundwater samples collected along a sampling transection that covers the salinity transition zone were analyzed for spatial and temporal distribution of major ions cl so 4 2 na k mg 2 and ca 2 and ancillary parameters such as salinity ph temperature and total alkalinity the seawater freshwater interface sfi based on different ions ionic delta of major ions phreeqc based saturation index si of minerals are used to systematically investigate geochemical processes such as cation exchange precipitation dissolution of minerals and sulfate reduction under the effect of seasonal hydrologic variation compared to cl based sfi the landward movements of cation based sfi and seaward movement of so 4 2 based sfi indicate that the coastal aquifer serves as the source of cations and sink of so 4 2 for groundwater the sfi is sensitive to seasonal hydrologic variation due to the variation of land sea hydraulic gradient the cation exchange and precipitation dissolution of minerals are dynamic and complex in coastal groundwater mixing zone the simultaneous enrichment of all cations is found in the aquifer due to external input of a specific cation the sulfate reduction is responsible for so 4 2 depletion and also the enrichment of total alkalinity in coastal groundwater mixing zone because gypsum precipitation does not occur according to mineral si analysis the cation exchange is very sensitive to the seasonal hydrologic variation while the sulfate reduction is not obviously influenced

the effect of trapped liquid crystallization on cumulus mineral compositions in layered intrusions a series of calculations have been carried out to evaluate the effect on cumulus mineral compositions of solidification of trapped intercumulus liquid in orthocumulates the calculation assumes local equilibrium between phases and that the system remains chemically closed during crystallization of the trapped liquid the latter assumption is held to be valid on a scale of tens to hundreds of centimeters it is not necessary to know the composition of the trapped liquid as the calculation only requires an estimate of feo content and trapping temperature the change in composition of a mineral from that of the initially precipitated cumulus crystals to the final composition after complete solidification is termed the trapped liquid shift its magnitude depends on the modal proportions of cumulus phases and the initial porosity and is only weakly dependent on initial phase compositions trapped liquid shifts are significant when compared with mineral composition changes occurring during fractional crystallization crystallization of 30 trapped liquid gives rise to shifts of up to 10 mol percent in mg number of olivine or pyroxene the size of the shift becomes greater when the initial cumulus assemblage has a lower total feo mgo content and vice versa as a result of the relationship between trapped liquid shift and cumulus mode mineral composition variations and trends may be generated in sequences of cumulates which originally had constant compositions of cumulus minerals for example in a cyclic unit grading from a pyroxenitic base to an anorthositic top crystallization of a uniform proportion of trapped liquid will result in an apparent iron enrichment trend from bottom to top of the cycle as has been observed in the upper critical zone of the bushveld complex

intra sill magmatic evolution in the cummings complex abitibi greenstone belt tholeiitic to calc alkaline magmatism recorded in an archaean subvolcanic conduit system abstract the stratigraphy of the abitibi greenstone belt in the chibougamau area southern superior province quebec is dominated by 2 cycles of mafic felsic metavolcanic and metasedimentary rocks constituting the roy group which is riddled by metagabbroic sills 25 the dore lake complex dlc 2728 ma is emplaced into the lower roy group the cummings complex sills 2717 ma were injected between the bruneau member and blondeau formations of the 2nd roy group cycle the sills of the cummings complex roberge ventures and bourbeau sills contain metaperidotite metapyroxenite metagabbro and metagranophyric facies the trace element contents of melts in equilibrium with these metacumulate rocks were calculated and are compared to roy group lavas to clarify the regional magmatic history many dlc model melts have fractionated trace element profiles with lile lree enrichment hree depletion and negative nb ta anomalies suggesting that the dlc formed largely from calc alkaline melts extracted from garnet bearing residues the dlc is coeval with and shows geochemical resemblances to waconichi formation tuffs the felsic cap of the 1st roy group cycle suggesting it could represent the waconichi s shallow magma chamber meta anorthosite rafts from the para autochtonous zone of the grenville province yield model melts closely resembling those of the dlc and are correlated on this basis most roy group sills yield model melts with trace element patterns typical of archaean tholeiites suggesting they fed the regionally dominant tholeiitic volcanic plain lavas of the roy group models for the cummings complex imply that it contained two types of magma model melts from the roberge sill have strongly fractionated calc alkaline like trace element patterns while those of the ventures and bourbeau sills are mostly flat n morb normalized tholeiitic like patterns that cannot be derived from the roberge sill melts by fractional crystallization the roberge sill must have a separate magmatic stem and represents the feeder system for a calc alkaline volcano possibly represented in part by blondeau formation rhyolites andesites and basalts if this is correct the roberge may be older than the ventures and bourbeau sills which would have fed the tholeiitic base of a third magmatic cycle since eroded

geochemical investigation of salt water intrusion into a coastal carbonate aquifer mallorca spain geochemical processes occurring within the mixing zone on mallorca spain were investigated in relation to the diagenesis of carbonate minerals and to the development of porosity and permeability within the pleistocene limestone aquifer rock core and ground water samples were obtained from the fresh water zone the mixing zone and the top of the sea water zone at two sites near the coast ground water withdrawals in the vicinity of one study site depressed the water table to below sea level resulting in sea water encroachment and a thin mixing zone laboratory tests conducted on the rock core indicated that porosity and hydraulic conductivity were not enhanced within the transitory location of the present day mixing zone vuggy zones in the core correspond to the approximate location of the water table because the ground water was supersaturated with respect to the carbonate minerals dissolution of the limestone aquifer is no predicted for the present day mixing zone results of mass balance and source rock calculations indicated an excess of calcium and strontium in the mixing zone waters in relation to what was expected from conservative mixing these elevated concentrations are hypothesized to result from limestone dissolution in the vadose zone

anticipating and managing engineering problems in the complex karst environment karst environments are characterized by distinctive landforms and a peculiar hydrologic behavior dominated by subsurface drainage karst systems can be extremely complex heterogeneous and unpredictable due to the wide range of geological and hydrological controlling factors the great variability results in serious problems for engineers and in difficulties to characterize the karstified rock masses and in designing the engineering works to be performed the design and development of engineering projects in karst environments require specific approaches aimed at minimizing the detrimental effects of hazardous processes and environmental problems further karst aquifers that provide approximately 20 25 of the world s drinking water are extremely vulnerable to pollution due to the direct connection between the surface and the subsurface drainage the rapidity of the water flow in conduit networks and the very low depuration capability sinkholes are the main source of engineering problems in karst environments and may cause severe damage in any human structure the strategies and solutions that may be applied to mitigate sinkhole problems are highly variable and largely depend on the kind of engineering structure the karst setting and the typology and size of the sinkholes a sound geological model properly considering the peculiarities of karst and its interactions with the human environment is essential for the design of cost effective and successful risk reduction programs due to the unique direct interaction between surface and subsurface environments and the frequent ground instability problems related to underground karstification management of karst environments is a very delicate matter disregarding such circumstances in land use planning and development inevitably results in severe problems with high economic impacts karst environments require specific investigation methods in order to properly manage and safeguard the sensitive geo ecosystems and natural resources associated with them

differentiation of the cuthbert lake ultramafic dikes and related mafic dikes in the cuthbert lake region of north central manitoba northeasterly trending ultramafic mafic dikes part of the molson dike swarm show a range of composition from gabbro to olivine hornblende pyroxenite to hornblende peridotite the major dike which is ultramafic in composition is 60 m thick olivine and chromian spinel were the earliest cumulus phases formed in a subcrustal magma chamber before the emplacement of the dikes orthopyroxene and clinopyroxene were formed following emplacement at about 1120 c plagioclase and hornblende were the latest phases to crystallize from the intercumulus melt mineralogical and chemical variations across the major dike are interpreted to have resulted from flow differentiation of multiple injections of magma carrying suspended olivine crystals olivine phenocrysts changed their compositions from about fo87 to values ranging from fo80to fo73 as a function of the amount of intercumulus melt the composition of this melt is estimated to have been basaltic a mafic dike about 10 m thick and occurring about 20 m away from the main ultramafic dike is believed to have been formed from magmas that were tapped from an upper layer overlying the olivine rich zone in a subcrustal magma chamber separation must have occurred when clinopyroxene and plagioclase appeared on the liquidus

geochemical and isotopic evidence for palaeo seawater intrusion into the south coast aquifer of laizhou bay china this research aims to improve the current knowledge of groundwater salinisation processes in coastal aquifers using combined hydrochemical and isotopic parameters and inverse hydrochemical modelling field investigations were conducted in laizhou bay which is the area most seriously affected by seawater intrusion in north china during three sampling campaigns along a vertical transect in the changyiliutuan area 95 ground and surface water samples were collected for major ion and isotope analysis

multivariate statistical analysis and hydrogeochemical modelling of seawater freshwater mixing along selected flow paths case of korba coastal aquifer tunisia abstract groundwater sampling and piezometric measurements were carried out along two flow paths corresponding to two transects in korba coastal plain northeast of tunisia the study aims to identify hydrochemical processes occurring when seawater and freshwater mix those processes can be used as indicators of seawater intrusion progression and freshwater flushing into seawater accompanying submarine groundwater discharge sgd seawater fractions in the groundwater were calculated using the chloride concentration hierarchical cluster analysis hca was applied to isolate wells potentially affected by seawater in addition phreeqc was used to simulate the theoretical mixing between two end members seawater and a fresh brackish groundwater sample geochemical conventional diagrams showed that the groundwater chemistry is explained by a mixing process between two end members results also revealed the presence of other geochemical processes correlated to the hydrodynamic flow paths direct cation exchange was linked to seawater intrusion and reverse cation exchange was associated to the freshwater flushing into seawater the presence of these processes indicated that seawater intrusion was in progress an excess of ca that could not be explained by only cation exchange processes was observed in both transects dedolomitization combined to gypsum leaching is the possible explanation of the groundwater ca enrichment finally redox processes were also found to contribute to the groundwater composition along flow paths

hydrodynamic analysis of a mediterranean aquifer system with the use of hydrochemical and isotopical analysis as supporting tools the management of groundwater resources in coastal environments within the mediterranean basin has become of paramount importance especially in the light of global changes a typical example of such a hydrosystem is the lavrio basin in greece this research site involves two aquifer types granular and karstic formations that are hydraulically interconnected furthermore the proximity to the sea and the abstractions for irrigation and drinking water supply have led to the phenomenon of seawater intrusion the present study aims at analyzing the hydraulic hydrological and hydrogeological conditions of the area by means of hydrochemical and isotopical data interpretation as supporting tools which will inform and support the development of an integrated conceptual hydrogeological model of the area field investigations were conducted in order to collect piezometric and chemical data and use them to retrieve the quantitative and qualitative status of the local aquifer units new interpretation of an older dataset gave an insight into how the karstic aquifer behaves in terms of hydraulics the results have also demonstrated that there is a hydraulic connection between the different aquifers and the mediterranean sea while natural recharge was quantified for both aquifer types

basaltic magmatism on the moon a perspective from volcanic picritic glass beads abstract it is widely accepted that basaltic magmas are products of partial fusion of periodotite within planetary mantles as such they provide valuable insights into the composition structure and processes of planetary interiors those compositions which approach primary melt compositions provide the most direct information about planetary interiors and serve as a starting point to understand basaltic evolution within the collection of lunar samples returned by the apollo and luna missions are homogeneous picritic glass beads of volcanic origin these picritic glasses are our closest approximations to primary magmas as such these glass beads provide a unique perspective concerning the origin of mare basalts the characteristics of the lunar interior and processes in the early differentiation of the moon we have obtained trace element data for these picritic glasses using sims techniques these data and literature isotopic and experimental data on the picritic glasses are placed within the framework of mare basaltic magmatism the volcanic glasses are very diverse in their trace element characteristics for example they have a wide range of ree pattern shapes and concentrations like the crystalline mare basalts all picritic glasses have a negative eu anomaly unlike the crystalline mare basalts there is little correlation between the size of the eu anomaly and overall ree concentrations trace element differences among the various glasses suggests that a kreep component was incorporated into their mantle source this implies large scale mixing of the lunar magma ocean derived cumulate pile subtle differences among glasses suggest that local mixing of sources may also have been an important process preservation of subtle chemical differences in the picritic glasses and crystalline basalts may be interpreted as indicating that they were produced by small to moderate degrees of partial melting and that the lunar mantle did not experience extensive melting during episodes of mare volcanism several lines of evidence are consistent with the view that the picritic glasses were derived from mantle sources that were compositionally distinct from the sources for crystalline mare basalts these are parallel but no common liquid lines of descent chemical differences between picritic glasses and the more primitive crystalline mare basalts experimental studies indicating that the picritic glasses are multiply saturated at depths greater than that of the mare basalts differences in lead isotopic data and the mode of eruption i e fire fountaining for glass beads these data also provide circumstantial evidence that suggests that the picritic glasses were derived from a source somewhat more volatile rich than that of the mare basalts several petrogenetic models are suggested by the trace element characteristics of the picritic glasses 1 1 partial melting of heterogeneous lunar mantle at depths greater than 300 km to produce the parental magmas picritic for both the mare basalts and picritic glasses picritic magmas represented by glass beads were erupted to the surface with small degrees of fractional crystallization while mare basalts were produced by larger degrees of fractional crystallization 15 30 of similar but not identical picritic magmas 2 2 picritic magmas represented by the glass beads were generated at depths greater than 400 km in a volatile enriched relative to the mare basalt source heterogeneous mantle while mare basalts are fractional crystallization products of picritic magmas generated at depths of less than 400 km 3 3 the picritic magmas represented by the glass beads represent polybaric melting that initiated at depths of at least 1000 km a primitive mantle component or less processed cumulate mantle components may have been involved in the generation of the picritic glasses in any of these models

geochemical evolution and timescale of seawater intrusion into the coastal aquifer of israel this study is an attempt to quantify the geochemical processes and the timescale of seawater intrusion into a coastal aquifer from changes in the major ionic composition of the water and the natural distribution of the cosmogenic isotopes 14c and 3h for that purpose we sampled saline and brackish groundwaters from the israeli coastal aquifer a multilayer sampler mls was used to obtain very high resolution 10 cm profiles across the fresh saline water interface fsi the chemical and stable isotope data revealed three distinct water types end members that are located in different zones on the route to the coastal aquifer 1 slightly modified mediterranean seawater sws 2 slightly diluted with up to 20 fresh groundwater saline groundwater sds and 3 fresh groundwater fgw the sws samples generally show an excess of total alkalinity and total dissolved inorganic carbon dic and a depletion of 13cdic and 14cdic with respect to normal seawater indicating that anaerobic oxidation of organic matter is the first diagenetic reaction that affects seawater during its penetration into the bottom sediments sds waters appear when sws is slightly diluted gain ca2 and sr2 and is depleted in k suggesting that the main processes that transform sws into sds are slight dilution with fresh groundwater and cation exchange at the fresh saline water interface sds generally shows conservative mixing with fgw inspection of chemical data from coastal aquifers around the world indicates that intensive ion exchange in slightly diluted saline groundwater is a globally important phenomenon of seawater intrusion most of our saline groundwater samples contain substantial amounts of 3h suggesting that penetration of mediterranean seawater and its inland travel to a distance of 50 100 m onshore occurred 15 30 yr ago this is supported by the 14cdic mass balance that explains the relatively low 14cdic activities in the sds as influenced by diagenesis and not by simple radioactive decay

topography and geoid anomalies due to density heterogeneities at the base of the thermal lithosphere application to oceanic swells and small wavelength geoid lineations summary the surface topography gravity and geoid associated with loads situated at the base of the thermal lithosphere are computed the model lithosphere is composed of a viscous lower layer with depth dependent viscosity overlain by an elastic lid when the viscosity varies strongly with depth the amplitude of the surface topography decreases rapidly as the wavenumber characterizing the mass anomaly increases the response for this two layer lithosphere differs substantially from the response computed for the loading from below of an elastic lid if the 200km wavelength geoid anomalies observed in the oceans are due to convective instabilities at the base of the lithosphere a positive geoid anomaly with an amplitude reaching 30 to 50cm is expected over a cold downwelling for ages greater than 10 myr no detectable topography associated with the lineations should be present for ages greater than 20 myr our model predicts that some topographic anomalies might be visible for younger ages if 1000 km broad swells are due to light material at a depth of about 100 km the associated geoid over topography ratios are quite reduced compared to those predicted by the long wavelength linear relationship usually employed for estimating the apparent compensation depth

factors controlling mechanisms of groundwater salinization and hydrogeochemical processes in the quaternary aquifer of the eastern nile delta egypt in this study combining interpretations of conservative dissolved ions and environmental isotopes in water were used to investigate the main factors and mechanisms controlling groundwater salinization and hydrogeochemical processes in the eastern nile delta egypt hydrogeochemical and isotopic study has been carried out for 61 water samples from the study area total dissolved solid tds contents of groundwater are highly variable rising along flowpath from the south 410 mg l to the north 14 784 mg l implying significant deterioration and salinization of groundwater based on tds and ionic ratios groundwater samples were classified into three groups in low saline groups water chemistry is greatly influenced by cation exchange mineral dissolution precipitation anthropogenic pollutants and mixing with surface water whilst in high saline groups water chemistry is affected by salt water intrusion reverse cation exchange and evaporation the chemical constituents originating from saline water sources reverse ion exchange and mineral dissolution are successfully differentiated using ionic delta and saturation index approaches the 18o 2h relationship plots on a typical evaporation line suggesting potential evaporation of the recharging water prior to infiltration isotope evidence concludes that the groundwater have been considerably formed by mixing between depleted meteoric water recharged under different climatic conditions and recently infiltrating enriched surface water and excess of irrigation water the 18o data in conjunction with chloride concentrations provide firm evidence for impact of dissolution of marine origin evaporite deposits during past geologic periods on groundwater salinity in the northern region moreover the relation between 14c activities and cl concentration confirms this hypothesis

the geology and geochemistry of the waterfall gorge section of the insizwa complex with particular reference to the origin of the nickel sulfide deposits the jurassic aged mafic rocks from the waterfall gorge section of the insizwa layered complex transkei range in composition from olivine gabbro and picrite basal zone through a series of gabbros central zone to monzonites roof zone the compositional data for the mineral phases olivine plagioclase bronzite and augite show significant features in the basal gabbro the trend in compositional variation is the reverse of that seen in the central zone of the intrusion and olivines from the picrite unit are the most forsteritic in the intrusion but they are depleted in ni compared to olivines from the basal gabbro and central zone the data for olivines from the picrite unit at tabankulu exhibit a similar but more significant degree of depletion mineral compositional and whole rock geochemical data for the basal olivine gabbro suggest that olivine control is primarily responsible for the compositional variation in this unit at insizwa however to account for the upward increase in the forsterite content of the cumulus olivine at the base the intrusion of successively less fractionated batches of a low mgo magma is suggested we suggest that the depletion of the olivines in ni can be attributed to the equilibration of the parent magma with sulfide and we show that these data are consistent with experimental distribution coefficient data for ni between olivine and sulfide permitting broad constraints to be placed on the grade as well as the tonnage and location of the ore extrapolation of these conclusions to the tabankulu intrusion suggest that the highly ni depleted olivines of the picrite have equilibrated with a magma from which a particularly high proportion of sulfide has segregated geophysical data fail to detect a massive orebody at the base of the intrusion though several small bodies may exist it is suggested that saturation may have occurred at depth and only a small amount of sulfide has been transported to the surface in the picrite and concentrated in depressions at the base of the intrusion massive and disseminated magmatic ni sulfide mineralization is confined to the lower basal zone and shows a consistent fractionation into pyrrhotite pentlandite rich ore at the base and chalcopyrite rich ore at the top in both massive sheets and globular ore the cause of sulfur saturation cannot be attributed to the reduction of the solubility of sulfur in the magma by increasing the sio 2 concentration contamination despite the close association of the ore with granophyric segregations in the basal olivine gabbro indeed the major and trace element data argue strongly against wholesale assimilation of crust at any stage in the production of the basal gabbro

deciphering basaltic magmatism on the moon from the compositional variations in the apollo 15 very low ti picritic magmas picritic glass beads of volcanic origin have been interpreted as representing extremely primitive lunar magmas that approach primary magma compositions based on this they have been used for developing models for lunar magmatism estimating the mineralogical and chemical characteristics of their mantle sources constraining the dynamics and structure of the lunar mantle developing models for lunar core formation reconstructing the bulk composition of the moon and evaluating the genetic relationships between the earth and the moon yet we still do not truly understand many aspects of the compositional diversity among individual glass types or even within a single glass type using high precision ion microprobe techniques we have analyzed a total of forty very low ti glass beads from the apollo 15 a15 site and twenty additional picritic glass beads from other sampling sites for a suite of highly compatible ni co weakly compatible to weakly incompatible mn cr v and highly incompatible ce ti zr nb elements within the a15 very low ti glass population ni and co concentrations are positively correlated exhibit limited fractionation of ni co and are distinctive for individual glass groups as defined by major elements manganese is also colinear with both ni and co the highly incompatible elements also appear to be generally colinear with ni co and mn although there are distinguishable compositional offsets in the glass populations the ni co ratio does not differ dramatically among the very low ti glasses from other sampling sites although incompatible element concentrations may differ significantly these trace element data eliminate fractional crystallization and partial melting of a homogeneous source under extremely low fostaggered2 conditions as possible models for the origin of the compositional variations observed in the a15 very low ti glass population these data are consistent with the generation of these magmas through partial melting of a spatially restricted heterogeneous lunar magma ocean lmo cumulate sequence the compositional variation in these magmas can be produced by at least two different melting processes 1 partial melting of a cumulate sequence consisting of relatively early cumulates with a higher proportion of an intercumulus melt component green glass a d e and later cumulates with lower proportions of an intercumulus melt component green glass c 2 different degrees of partial melting of a cumulate sequence small degrees of partial melting less than 5 of a more primitive cumulate mantle source will generate one group of magmas green a d e whereas a group of other picritic magmas green c were produced by larger degrees of partial melting 10 to 20 of a mineralogically similar but a more evolved cumulate mantle source in both models the green b glass group is formed by either cumulate commingling or magma mixing processes these magmas cannot be rapidly transported from the source region to the lunar surface in a single eruptive event without extensive fractional crystallization yet the colinear relationship among ni co and mn is not compatible with extensive and variable fractional crystallization therefore a polybaric melting model as suggested by longhi 1992b appears to be the only alternative to producing relatively unfractionated apollo 15 very low ti picritic magmas with high pressure signatures the trace element data provides additional constrains for this type of model

evidence for the trapped liquid shift effect in the mount ayliff intrusion south africa postcumulus trapped liquid shift in layered complexes produces cumulate minerals with more fractionated compositions than the original primary phases this effect is shown by olivine compositions from the base of the mount ayliff intrusion where varying proportions of olivine to interstitial liquid produce a suite of rocks which define a tight linear trend on a binary whole rock plot of mgo versus feo extrapolation of this trend constrains the composition of the primary cumulus olivine to the range fo84 86 whereas olivine actually present have compositions fo77 83 the magnitude of the discrepancy between the theoretical and observed olivine compositions correlates directly with the weight fraction of interstitial liquid these observations are quantitatively predicted by the trapped liquid shift model they also argue against significant migration of residual liquid trapped liquid shift is documented over a vertical interval of 60 m it occurred in rocks lying only 1 m above the basal contact of the intrusion and hence must be a comparatively rapid process

response of the mediterranean and dead sea coastal aquifers to sea level variations 1 the present study examines the response of groundwater systems to expected changes in the mediterranean sea rise of 1cm yr and dead sea levels decline of 1 m yr a fast response is observed in the dead sea coastal aquifer exhibited both in the drop of the water levels and in the location of the fresh saline water interface no such effect is yet observed in the mediterranean coastal aquifer as expected numerical simulations using the feflow software show that the effect of global sea level rise depends on the coastal topography next to the shoreline a slope of 2 5 is expected to yield a shift of the interface by 400 m after a rise of 1m 100 years whereas a vertical slope will yield no shift reduced recharge due to climate change or overexploitation of groundwater also enhances the inland shift of the interface

geochemical and palaeohydrological controls on the composition of shallow groundwater in the netherlands with the exception of the south of the country the netherlands has a strong bipartite hydrogeology the holocene part with a coastal dune belt and confining top layer of clay and peat further inland and the pleistocene where thick phreatic aquifers dominate this research aimed to ascertain the geochemical and palaeohydrological controls on the composition of shallow groundwater in 27 regions close to 6000 groundwater analyses were grouped and interpreted in terms of 1 salinity 2 redox status 3 acid base and carbonate status and 4 natural nutrients nh4 and po4 the a priori classification into geographical regions and geological formations revealed many statistically significant differences in medians even for geologically or geographically related data groups the compound specific interpretation indicates that there are geogenically controlled systematic differences in groundwater composition at the regional scale the imprint of the geological sediments on the groundwater composition decreases in the order marine estuarine via limnological fluvial to aeolian the imprints with respect to ph and carbonate status natural nutrients and redox status are not necessarily interrelated the vertical stratification in groundwater composition turns out to be often limited at the regional scale due to mutual occurrence of infiltrating and exfiltrating groundwater in regions and either the presence of a highly reactive holocene confining top layer or temporal changes in contamination in the holocene part the salinity is controlled by the palaeoenvironmental conditions during the holocene and by the recharge origin the average cl concentration decreases from estuarine via lagoonal to the former zuider sea which was a bay the most reduced states and also the highest nutrient concentrations and highest co2 pressure are related to the presence of holocene marine sediments in the confining top layer degradation of marine derived organic matter as a nutrient source is likely more intense in the holocene deposits than that of peat and sedimentary remnants of terrestrial plants a broad range in ph carbonate status and redox status is encountered in the pleistocene part here the palaeohydrological evolution in terms of carbonate leaching together with the geological controls on the calcareous nature of the shallow sedimentary deposits cause regional differences in ph calcite saturation and silicate weathering one region with late pleistocene limnological deposits has deviating groundwater characteristics and appears more similar to the holocene part of the netherlands furthermore reactive fe is not abundant in all pleistocene fluvial sediments nor is it maximally mobilised as not all anoxic groundwater in these sediments is siderite saturated this leads to considerable intra and inter region variability 2013 elsevier ltd

14c excess in deep sea sediments porewater driven by diffusionߞsoutheast mediterranean core profiles in the deep se mediterranean sea revealed a significant 14 c excess in the total dissolved inorganic carbon dic of porewater as compared to the 14 c of the sediments below the bioturbation zone down to core bottom 2 m the main observation was that the age difference between porewater and sediments as calculated from the excess was not constant but rather increasing with depth the porewater apparent age was younger by 10 than the age of the sediment at the core top and gradually became younger by about 70 at the bottom of the core flux calculations and mass balances of the chemical and isotopic data suggest that this 14 c excess stems from a downward diffusive flux of 95 15 atoms of 14 c dic m 2 s 1 from the bioturbation zone and overlying bottom water into the sediment the 14 c dic flux is opposite in direction to the dic flux out of the sediment it is suggested here that the 14 c dic flux may severely interfere with age determination of small submarine brine lakes formed in the deep mediterranean in addition the 14 c excess should show up in authigenic carbonate phases precipitating within the sediment and hence may serve as a tool to identify the extent and duration of authigenic carbonate precipitation

study of shallow groundwater quality evolution under saline intrusion with environmental isotopes and geochemistry evolution of the shallow groundwater quality under saline intrusion in porous aquifer system has been studied with environmental isotopes and geochemistry in the laizhou bay area china two campaigns of water sampling from various sources were carried out in spring and winter for environmental isotopic and chemical analyses the origin of groundwater salinity from intrusion of both modern seawater and deep brine water was identified by analysing the correlations between 18o d t cl so 4 2 and electrical conductivity the results indicate that the brine is originated from evaporating and concentrating of intruded seawater and its d and 18o are different from modern seawater but similar to those of mixture of seawater with fresh groundwater it is hard to distinguish the salinity origin in this area by the d 18o relationship alone the relations between 18o and conductivity cl and so 4 2 have been used to identify the salinity origin due to the distinct difference in salinity between the brine and seawater conjunctively with use of t a threshold of t 12 tu was adopted to identify the origin of saline groundwater