geochemical mapping of magmatic gas water rock interactions in the aquifer of mount etna volcano abstract systematic analysis of major and minor elements in groundwaters from springs and wells on the slopes of mt etna in 1995 1998 provides a detailed geochemical mapping of the aquifer of the volcano and of the interactions between magmatic gas water bodies and their host rocks strong spatial correlations between the largest anomalies in pco2 ph and alkalinity k rb mg ca and sr suggest a dominating control by magmatic gas co2 and consequent basalt leaching by acidified waters of the shallow meteoric etnean aquifer most groundwaters displaying this magmatic type interaction discharge within active faulted zones on the s sw and e lower flanks of the volcanic pile but also in a newly recognised area on the northern flank possibly tracking a main n s volcano tectonic structure in the same time the spatial distribution of t c tds na li cl and b allows us to identify the existence of a deeper thermal brine with high salinity high content of b cl and gases co2 h2s ch4 and low k na ratio which is likely hosted in the sedimentary basement this hot brine reaches the surface only at the periphery of the volcano near the village of paterno where it gives rise to mud volcanoes called salinelle di paterno however the contribution of similar brines to shallower groundwaters is also detected in other sectors to the w bronte maletto sw adrano and se acireale suggesting its possible widespread occurrence beneath etna this thermal brine is also closely associated with hydrocarbon fields all around the volcano and its rise generally masked by the high outflow of the shallow aquifer may be driven by the ascent of mixed sedimentary magmatic gases through the main faults cutting the sedimentary basement

natural and anthropogenic factors affecting groundwater quality of an active volcano mt etna italy abstract new geochemical data on dissolved major and minor constituents in 276 groundwater samples from etna aquifers reveal the main processes responsible for their geochemical evolution and mineralisation this topic is of particular interest in the light of the progressive depletion of water resources and groundwater quality in the area multivariate statistical analysis reveal 3 sources of solutes a the leaching of the host basalt driven by the dissolution of magma derived co2 b mixing processes with saline brines rising from the sedimentary basement below etna c contamination from agricultural and urban wastewaters the last process highlighted by increased concentrations of so4 no3 ca f and po4 is more pronounced on the lower slopes of the volcanic edifice associated with areas of high population and intensive agriculture however this study demonstrates that natural processes a and b are also very effective in producing highly mineralised waters which in turn results in many constituents b v mg exceeding maximum admissible concentrations for drinking water

transformation textures mechanisms of formation of high pressure minerals in shock melt veins of l6 chondrites and pressure temperature conditions of the shock events the high pressure polymorphs of olivine pyroxene and plagioclase in or adjacent to shock melt veins smvs in two l6 chondrites sahara 98222 and yamato 74445 were investigated to clarify the related transformation mechanisms and to estimate the pressure temperature conditions of the shock events wadsleyite and jadeite were identified in sahara 98222 wadsleyite ringwoodite majorite akimotoite jadeite and lingunite naalsi3o8 hollandite were identified in yamato 74445 wadsleyite nucleated along the grain boundaries and fractures of original olivine the nucleation and growth of ringwoodite occurred along the grain boundaries of original olivine and as intracrystalline ringwoodite lamellae within original olivine the nucleation and growth of majorite took place along the grain boundaries or fractures in original enstatite jadeite containing assemblages have complicated textures containing particle like stringer like and polycrystalline like phases coexistence of lingunite and jadeite containing assemblages shows a vein like texture we discuss these transformation mechanisms based on our textural observations and chemical composition analyses the shock pressure and temperature conditions in the smvs of these meteorites were also estimated based on the mineral assemblages in the smvs and in comparison with static high pressure experimental results as follows 13 16 gpa 1900 c for sahara 98222 and 17 24 gpa 2100 c for yamato 74445

multivariate indications between environment and ground water recharge in a sedimentary drainage basin in northwestern china abstract a paucity of studies on the interaction between environment and ground water recharge severely restricts the ability of people to assess future water resources under changing environment in this study an effort to explore the relationship between the arid environment and ground water recharge was carried out using multivariate statistical techniques in a sedimentary drainage basin the jungar in northwestern china hierarchical cluster analysis hca and principal components analysis pca were performed based on hydrogeochemical data to assess the ground water recharge and its governing factors observation of the hca and pca analytical results revealed a division of seven clusters c1 to c7 and three principal components pc1 to pc3 which explained 59 6 16 6 and 10 9 of the variance respectively and thus accounted for the majority of the total variance in the original dataset based on these q mode hca clusters and r mode pac scores dominant environmental processes influencing recharge regimes were identified i e geogenic geomorphoclimatic and anthropogenic which separated the recharge regimes into four zones zone i to zone iv zones i and ii c4 c1 were associated to elevated hydroclimate degree coupled to low salinity zone iii c2 c3 was associated to moderately elevated salinity and evidently elevated contamination but coupled to low hydroclimate degree zone iv c5 c6 c7 was associated mainly to elevated salinity coupled to low or inverse hydroclimate degree it revealed that the geogenic processes are more significant 60 than the geomorphoclimatic 17 and anthropogenic 11 processes as a result the overall recharge process is rather heterogeneous and is strongly environment dominated in the jungar drainage system compared with other watersheds in arid environment a distinctive feature of the jungar waters is that they are affected by a combination of natural and non natural events rather than following a steady and continuous geological evolution these will continue to influence the recharge regime of the jungar for a long time due to its steady tectonics and arid climate however changing rainfall but not snow is becoming the key factor driving changes in ground water resources in this drainage system as results of the decades of warming and humidification in northwestern china

high pressure minerals in shocked meteorites heavily shocked meteorites contain various types of high pressure polymorphs of major minerals olivine pyroxene feldspar and quartz and accessory minerals chromite and ca phosphate these high pressure minerals are micron to submicron sized and occur within and in the vicinity of shock induced melt veins and melt pockets in chondrites and lunar howardite eucrite diogenite hed and martian meteorites their occurrence suggests two types of formation mechanisms 1 solid state high pressure transformation of the host rock minerals into monomineralic polycrystalline aggregates and 2 crystallization of chondritic or monomineralic melts under high pressure based on experimentally determined phase relations their formation pressures are limited to the pressure range up to 25 gpa textural crystallographic and chemical characteristics of high pressure minerals provide clues about the impact events of meteorite parent bodies including their size and mutual collision velocities and about the mineralogy of deep planetary interiors the aim of this article is to review and summarize the findings on natural high pressure minerals in shocked meteorites that have been reported over the past 50 years

a mesoscale eddy pair southwest of taiwan and its influence on deep circulation 1 a pair of mesoscale eddies namely an anticyclonic eddy ae and a cyclonic eddy ce generated southwest of taiwan was investigated using long term moored observations augmented with satellite and reanalysis data ae ce increased the upper ocean current to 100 cm s 50 cm s and generated temperature anomaly t up to 7 5 c 3 0 c the vertical structure of ae presented a phase difference between t and velocity with the core of t located south of the zero velocity line this phase difference induced a 28 5 12 0 tw 1 tw 1012 w westward eddy heat transport southwest of taiwan ae also presented strong nonlinearity in the upper ocean and yielded an annual mean volume transport of 0 86 0 15 sv energy analysis showed that both baroclinic and barotropic instabilities were important for the generation and growth of the eddy pair and contribution from wind work was relative small in the deep sea ae ce intensified the deep currents and generated large positive negative t the deep and surface currents flowed in opposite directions during the eddy events which is consistent with the interpretation that the eddy pair is dominated by the first baroclinic mode the observed deep penetrating eddy pair could greatly influence the deep circulation of the northeastern south china sea

discrete monitoring of chemical parameters in ground waters of mt etna volcano 2000 2006 abstract three sites of groundwater captation on mt etna volcano namely currone ilice and pavone were sampled systematically for six years from 2000 to 2006 for the determination of the major ionic composition of water the monitored sites were chosen among those most representative of the geochemical characteristics of the groundwater systems of the volcano the period studied was characterized by several strong eruptions of mt etna both at its summit craters and along its flanks the overall composition of the waters sampled at currone and ilice falls in the group of bicarbonate alkaline earth compositions whereas those from pavone show a bicarbonate alkaline composition in all sites however some samples show input of chlorine sulfate alkaline waters likely due to interaction between fresh groundwater and either acidic waters from so2 polluted rainwater more evident at pavone or geothermal brines more evident at currone significant temporal variations affected in a more or less marked way all of the parameters measured at the three sites basic statistical correlations among the parameters at each site allowed to discover a general coherent temporal behavior of all major ions dissolved in mt etna s ground waters factor analysis allowed showing up to three main groups of parameters with similar temporal behavior depending on the site a first group was explained by interaction between volcanic ground waters and geothermal fluids a second group was related with leaching of the host volcanic rocks by co2 rich volcanic water a third group was explained as due to input of plume so2 derived sulfate through water recharge using normal probability plots for each parameter at the three sites it was possible to reveal different geochemical populations explained as background anomalous values and possibly outliers plotting the temporal patterns of all the monitored parameters versus the concurrent eruptive episodes at mt etna we discovered significant correlations that although with different intensity and rate depending on the parameter and on the site highlighted several geochemical processes induced by interaction between cold groundwater and magmatic hydrothermal fluids mostly following changes in the ground permeability of the volcanic pile these processes seemed to be enhanced during periods of shallow magma accumulation inside of the volcano that preceded summit or flank eruptions occurred at mt etna during the monitored period

oxygen isotope composition of natural waters in the mt etna area oxygen isotopes of both rainwater and groundwater samples from mt etna were used to obtain information on recharge areas flow paths and the origin of wet air masses oxygen isotope composition was determined in rainwater samples collected for a period of 3 years october 1997 october 2000 in 11 rain gauges distributed along the flanks of mt etna from sea level to 2900 m of altitude values ranged from 213 8 to 1 9 the lowest values being measured at higher altitudes and or during cooler periods for rain gauges located from sea level up to 1000 m altitude volume weighted values defined an isotopic gradient of 22 7 km which is in the range observed in the mediterranean area higher altitude gauges yielded a much lower gradient 2 0 6 km probably due to the fact that vapour condensing at higher altitudes was mixed with an 18 o rich volcanic component deriving from the huge vapour output of the summit craters the oxygen isotope composition of about 210 groundwater samples collected all around the volcano ranged from 2 9 3 to 2 5 0 the higher values measured on the eastern flank indicated that recharge occurs at lower altitudes on this flank the low variability 0 30 0 65 of the monthly values gathered from 14 groundwater sampling points over a period of 2 years indicates that the groundwater system is isotopically well mixed some long term trends may be explained by variations in annual recharge due to the prevalent isotope composition of wet air masses q 2004 elsevier b v all rights reserved

soil gases and sar measurements reveal hidden faults on the sliding flank of mt etna italy abstract from october 2008 to november 2009 soil co 2 radon and structural field surveys were performed on mt etna in order to acquire insights into active tectonic structures in a densely populated sector of the south eastern flank of the volcano which is involved in the flank dynamics as highlighted by satellite data insar the studied area extends about 150 km 2 in a sector of the volcano where insar results detected several lineaments that were not well defined from previous geological surveys in order to validate and better constrain these features with ground data evidences soil co 2 and soil radon measurements were performed along transects roughly orthogonal to the newly detected faults with measurement points spaced about 100 m in each transect the highest co 2 values were found very close to the lineaments evidenced by insar observations anomalous soil co 2 and radon values were also measured at old eruptive fractures in some portions of the investigated area soil gas anomalies were rather broad over transects probably suggesting a complex structural framework consisting of several parallel volcano tectonic structures instead of a single one soil gas measurements proved particularly useful in areas at higher altitude on mt etna i e above 900 m asl where insar results are not very informative are fairly limited and allowed recognizing the prolongation of some tectonic lineaments towards the summit of the volcano at a lower altitude on the volcanic edifice soil gas anomalies define the active structures indicated by insar results prominently down to almost the coastline and through the northern periphery of the city of catania coupling insar with soil gas prospecting methods has thus proved to be a powerful tool in detecting hidden active structures that do not show significant field evidences

an evaluation of ambient sulphur dioxide concentrations from passive degassing of the sulphur springs saint lucia geothermal system implications for human health abstract sulphur springs park in saint lucia is a site of energetic geothermal activity associated with the potentially active soufriere volcanic centre the park is one of saint lucia s most important tourist attractions and is marketed as the world s only drive in volcano it has an on site staff of tour guides and vendors as well as over 200 000 visitors annually there are also a number of residents living in the areas bordering the park recreational use is made of the geothermal waters for bathing application of mud masques and in some cases drinking as part of the university of the west indies seismic research centre s uwi src s overall volcano monitoring programme for saint lucia the volcanic emissions at sulphur springs hot springs mud pools and fumaroles have been regularly monitored since 2001 in recent years visitors staff and management at the park have expressed concern about the health effects of exposure to volcanic emissions from the hydrothermal system in response to this src has expanded its regular geothermal monitoring programme to include a preliminary evaluation of ambient sulphur dioxide so2 concentrations in and around the park to assess the possible implications for human health passive diffusion tubes were used to measure the atmospheric so2 concentrations at various sites in sulphur springs park ssp in the town of soufriere and in the capital of castries measurements of average monthly ambient so2 with the passive samplers indicated that during the dry season period of april to july 2014 concentration at sites closest to the main vents at ssp group 1 which are routinely used by staff and visitors frequently exceeded the who 10 minute aqg for so2 of 500 g m3 however for sites that were more distal to the main venting area groups 2 and 3 the average monthly ambient so2 did not exceed the who 10 minute aqg for so2 of 500 g m3 during the entire monitoring period the measured concentrations and dispersion patterns of ambient so2 at ssp appear to be influenced by rainfall proximity to the fumarolic vents altitude local topography local atmospheric circulation and plume dispersion and anthropogenic sources brochures and posters were prepared for public distribution and display on possible gas hazards that may be encountered at ssp and precautionary measures that may be taken by visitors to help minimise potential risk from elevated exposure to volcanic gases

sea level induced variations in clay mineral composition in the southwestern south china sea over the past 17 000 yr variations in clay mineral composition of sediment cores from the margin and continental slope of the sunda shelf southern south china sea se asia covering the past 17 000 yr reflect changing influences of sediment sources together with clay mineral partitioning processes in shallow waters we identify the deglacial sea level rise as the principal factor driving these changes during the late glacial high values of kaolinite are interpreted to reflect a higher contribution of clays from soils that have formed on the exposed sunda shelf and in the southern archipelagos of indonesia at this time core sites were located in close proximity to the mouths of the sunda shelf palaeo drainage systems on the emerged shelf sundaland the progressive landward displacement of the coastline and breakdown of these vast drainage systems during deglaciation led to a decrease in influence of the kaolinite rich southern sources when the coastline had retreated closely to its present day position in mid holocene times the former dominance of southern sources was replaced by a stronger influence of illite rich sources e g borneo the overriding control of sea level changes on the clay mineral distribution patterns precludes a definite climatic interpretation of clay mineral data in terms of climatic monsoonal changes in such highly dynamic sedimentary environment

delineation of temporal variability and governing factors influencing the spatial variability of shallow groundwater chemistry in a tropical sedimentary island summary an attempt has been made to delineate the temporal variability and factors governing the shallow groundwater chemistry using analysis of variance anova and multivariate analysis notably r mode factor fa and hierarchical cluster analysis hca subsequently geostatistical isoplethic maps were applied to convey better understanding on the distribution of selected groundwater parameters the manukan island s shallow aquifer with sedimentary setting that constantly abstracted for freshwater supply has been selected for this study one way anova suggested that neither changes of tide level nor rainfall volume appeared to exert significant influence on the groundwater chemistry of the small island rather the groundwater chemistry was greatly governed by influence from seawater intrusion which characterized by considerable amount of ca na and cl such condition was well explained by a piper diagram where most plots were situated at the middle diamond shaped diagram indicating mixing condition fa likewise revealed that the shallow groundwater receives marked influence from carbonate dissolution and silicate weathering processes especially boreholes located in the inland area this can be clearly noted from the distinct groupings of relationships among different factors hca classified boreholes into three groups according to their locations in the coastal area suggesting significant chemical variations between boreholes with distance from coast such distribution pattern was particularly evident in the isoplethic map overall it appears that the shallow groundwater in the tropical island is not an appropriate source for drinking water in concern to its exceptionally high salinity and several elevated minor elements mn pb and se for this it is suggested that efforts in exploring other alternative sources should be performed outright

variations of cl f and s in mount etna s plume italy between 1992 and 1995 this study investigates data on the cl f and s concentrations of plume filter samples collected between 1992 and 1995 from mount etna the samples were collected during eruptive and noneruptive activity and show fairly constant cl f ratios but wide variation in the cl s ratios the determination of the cl f ratio between 5 and 14 allows an estimate of f degassing to be derived that ranges from 10 to 30 of the initial f content of the magma the variation in the cl s ratio fits an empirical two stage degassing model where gas with high cl s ratio is discharged during quiescient degassing and gas with low cl s ratios is discharged during eruptive degassing the typical permanent degassing occurs from a depth at which chlorine exsolution exceeds sulfur exsolution cl s 1 the opposite of this behavior is observed during eruptive periods when significant sulfur degassing occurs because magma degasses at near atmospheric pressure cl s 0 1 the cl s ratio in the plume characterizing the type of degassing has the potential to be a useful geochemical tool for monitoring the volcano

discovery of bridgmanite the most abundant mineral in earth in a shocked meteorite meteorites exposed to high pressures and temperatures during impact induced shock often contain minerals whose occurrence and stability normally confine them to the deeper portions of earth s mantle one exception has been mgsio 3 in the perovskite structure which is the most abundant solid phase in earth here we report the discovery of this important phase as a mineral in the tenham l6 chondrite and approved by the international mineralogical association specimen ima 2014 017 mgsio 3 perovskite is now called bridgmanite the associated phase assemblage constrains peak shock conditions to 24 gigapascals and 2300 kelvin the discovery concludes a half century of efforts to find identify and characterize a natural specimen of this important mineral

estimating shock pressures based on high pressure minerals in shock induced melt veins of l chondrites here we report the transmission electron microscopy tem observations of the mineral assemblages and textures in shock induced melt veins from seven l chondrites of shock stages ranging from s3 to s6 the mineral assemblages combined with phase equilibrium data are used to constrain the crystallization pressures which can be used to constrain shock pressure in some cases thick melt veins in the tenhaml6 chondrite contain majorite and magnesiowstite in the center and ringwoodite akimotoite vitrified silicate perovskite and majorite in the edge of the vein indicating crystallization pressure of 25 gpa however very thin melt veins 5 30 m wide in tenham contain glass olivine clinopyroxene and ringwoodite suggesting crystallization during transient low pressure excursions as the shock pressure equilibrated to a continuum level melt veins of umbarger include ringwoodite akimotoite and clinopyroxene in the vein matrix and fe2sio4 spinel and stishovite in sio2 feo rich melt indicating a crystallization pressure of 18 gpa the silicate melt veins in roy contain majorite plus ringwoodite indicating pressure of 20 gpa melt veins of ramsdorf and nakhon pathon contain olivine and clinoenstatite indicating pressure of less than 15 gpa melt veins of kunashak and la lande include albite and olivine indicating crystallization at less than 2 5 gpa based upon the assemblages observed crystallization of shock veins can occur before during or after pressure release when the assemblage consists of high pressure minerals and that assemblage is constant across a larger melt vein or pocket the crystallization pressure represents the equilibrium shock pressure

sediment flux and the anthropocene data and computer simulations are reviewed to help better define the timing and magnitude of human influence on sediment flux the anthropocene epoch impacts on the earth surface processes are not spatially or temporally homogeneous human influences on this sediment flux have a secondary effect on floodplain and delta plain functions and sediment dispersal into the coastal ocean human impact on sediment production began 3000 years ago but accelerated more widely 1000 years ago by the sixteenth century societies were already engineering their environment early twentieth century mechanization has led to global signals of increased sediment flux in most large rivers by the 1950s this sediment disturbance signal reversed for many rivers owing to the proliferation of dams and sediment load reduction below pristine conditions is the dominant signal today a delta subsidence signal began in the 1930s and is now a dominant signal in terms of sea level for many coastal environments overwhelming even the global warming imprint on sea level humans have engineered how most water and sediment are discharged into the coastal ocean hyperpycnal flow events have become more common for some rivers and less common for other rivers bottom trawling is now widespread suggesting that even continental shelves have received a significant but as yet quantified anthropocene impact the anthropocene attains the level of a geological climate event such as that seen in the transition between the pleistocene and the holocene

groundwater chemistry and mass transfers in the independence aquifer central mexico by using multivariate statistics and mass balance models in the light of progressive depletion of groundwater reservoir and water quality deterioration of the independence aquifer an investigation on chemical data of dissolved major and minor constituents in 246 recent groundwater samples was performed the main objective was the detection of processes responsible for the geochemical evolution and mineralization throughout the area multivariate techniques revealed different sources of solutes a dissolution of calcium and magnesium carbonate minerals b weathering of acid volcanic minerals c alteration of manganese containing alkaline silicates d leaching of halite deposits of meteoric origin e contamination from agricultural and urban wastewaters and f evaporative effects due to intensive irrigation although nitrate contamination is associated with pollution from intensive cultivated areas natural contamination plays an important role in the study area the investigation reveals that weathering of acid volcanic rocks rhyolite and oxidation of arsenic bearing sulfide minerals are the responsible processes for high fluorine up to 16 mg l and arsenic up to 0 12 mg l contents respectively exceeding the mexican maximum admissible concentration for drinking water except for kaolinite all recharge processes are dissolution oriented co2 calcite dolomite k feldspar plagioclase silicate precipitation amorphous silica and chalcedony is of growing importance in discharge zones cation exchange is not an important issue in the whole study area

40ar 39ar age of northwest africa 091 more evidence for a link between l chondrites and fossil meteorites abstract most 40ar 39ar ages of l chondrites record an event at approximately 500 ma indicating a large collisional impact at that time however there is a spread in ages from 400 to 600 ma in these meteorites that is greater than the analytical uncertainty identification of and correction for trapped ar in a few l chondrites has given an age of 470 6 ma this age coincides with ordivician fossil meteorites that fell to earth at 467 2 ma as these fossil meteorites were originally l chondrites the apparent conclusion is that a large impact sent a flood of l chondrite material to earth while material that remained on the l chondrite parent body was strongly heated and reset we have reduced 40ar 39ar data for northwest africa 091 using various techniques that appear in the literature including identification and subtraction of trapped ar these techniques give a range of ages from 455 to 520 ma and show the importance of making accurate corrections by using the most straightforward technique to identify and remove a trapped ar component which is neither terrestrial nor primordial an 40ar 39ar age of 475 6 ma is found for northwest africa 091 showing a temporal link to fossil meteorites in addition high temperature releases of northwest africa 091 contain evidence for a second trapped component and subtraction of this component indicates a possible second collisional impact at approximately 800 ma this earlier age coincides with 40ar 39ar ages of some h and l chondrites and lunar samples

high pressure phases in shock induced melt of the unique highly shocked ll6 chondrite northwest africa 757 northwest africa 757 is unique in the ll chondrite group because of its abundant shock induced melt and high pressure minerals olivine fragments entrained in the melt transform partially and completely into ringwoodite plagioclase and ca phosphate transform to maskelynite lingunite and tuite two distinct shock melt crystallization assemblages were studied by fib tem analysis the first melt assemblage which includes majoritic garnet ringwoodite plus magnetite magnesiowustite crystallized at pressures of 20 25 gpa the other melt assemblage which consists of clinopyroxene and wadsleyite solidified at 15 gpa suggesting a second veining event under lower pressure conditions these shock features are similar to those in s6 l chondrites and indicate that nwa 757 experienced an intense impact event comparable to the impact event that disrupted the l chondrite parent body at 470 ma

back transformation of high pressure phases in a shock melt vein of an h chondrite during atmospheric passage implications for the survival of high pressure phases after decompression abstract we investigated the h6 chondrite yamato 75267 in which a fusion crust cuts a shock melt vein the shock vein region more than 280 m from the fusion crust contains high pressure phases such as ringwoodite majorite pyrope ss garnet and naalsi 3 o 8 hollandite however the shock vein close to the fusion crust entirely consists of the low pressure polymorphs olivine low ca pyroxene and plagioclase glass the boundary between low and high pressure phase regions is parallel to the fusion crust during the atmospheric passage the peripheral part of the chondrite was melted to form the fusion crust our microscopic laser micro raman electron microprobe investigations and calculations indicate an area up to 300 m from the fusion crust experienced a temperature of 1400 c after 3 s during the melting of the peripheral part the high pressure phases would at this conditions quickly transform back to their low pressure polymorphs the result obtained here indicates that post shock temperatures in the interior part of the veins were much lower than 1400 c thus leading to the survival of high pressure phases in heavily shocked chondrites

investigating the history of east asian monsoon and climate during the last glacial interglacial period 0 140 000 years mineralogy and geochemistry of odp sites 1143 and 1144 south china sea abstract monsoon climate is an important component of the global climatic system a comprehensive understanding of its variability over glacial interglacial time scales as well as of its effects on the continent and in the ocean is required to decipher links between climate continental weathering and productivity a detailed multiproxy study including bulk and clay mineralogy grain size analysis phosphorus geochemistry sedex extraction organic matter characterization and nitrogen stable isotopes was carried out on samples from odp sites 1143 and 1144 leg 184 south china sea covering the past 140 000 years we tentatively reconstruct the complex sedimentation and climatic history of the region during the last glacial interglacial cycle when sea level variations linked to the growth and melting of ice caps interact with monsoon variability during interglacial periods of high sea level summer monsoon was strong and humid and warm climate characterized the adjacent continent and islands clay minerals bear signals of chemical weathering during these intervals high calcite and reactive phosphorus mass accumulation rates mars indicate high productivity especially in the southern region of the basin during glacial intervals strong winter monsoon provided enhanced detrital input from the continent as indicated by high detrital mar glacial low sea level resulted in erosion of sediments from the exposed sunda shelf to the south and clay mineral variations indicate that warm and humid conditions still prevailed in the southern tropical areas enhanced supply of nutrients from the continent both by river and eolian input maintained high primary productivity reduced circulation during these periods possibly induced active remobilization of nutrients such as phosphorus from the sediments intense and short cold periods recorded during glacial and interglacial stages correlate with loess records in china and marine climatic records in the north atlantic confirming a teleconnection between low and high latitude climate variability

processes controlling the distribution of boron and chlorine in natural waters in iceland abstract the concentrations of b and cl in natural waters in iceland lie in the range 0 001 10 and 1 20 000 ppm respectively lowest concentrations occur in surface and groundwaters in the central highlands highest cl concentrations are found in high temperature waters on the reykjanes peninsula and highest b concentrations in well waters from high temperature geothermal systems in the axial zones of the active volcanic belts the b and cl contents of icelandic basalts are 0 1 6 6 and 75 750 ppm respectively these large variations are considered to result from variable degassing during consolidation as well as concentration variations in the initial magma tholeftes are lowest in both elements av 1 2 ppm b and 170 ppm ci transitional basalts intermediate av 2 1 ppm b and 240 ppm ci and alkali basalts highest av 3 8 ppm b and 340 ppm cl cl b ratios in tholeiites are most often within 25 50 but somewhat lower in alkali basalts most geothermal waters contain b and cl within 0 05 1 and 10 100 ppm respectively these rather low values are attributed to the low content of b and cl in the basaltic rock the b and cl distribution in the icelandic natural waters indicate that these elements act as essentially incompatible their sources of supply include 1 the atmosphere seawater spray and aerosols 2 the rock with which the water interacts 3 seawater groundwater and 4 magma intrusions in surface water and nonthermal groundwater the dominant source of supply of cl is seawater spray and aerosols but the soil and rock contribute often significantly to the b in these waters their cl b ratio is similar to that of seawater 1330 or somewhat lower boron and cl concentrations generally increase with water temperature warm waters cl b ratios intermediate between those of seawater and basalt with increasing temperature this ratio decreases and gradually approaches that of the rock some high temperature geothermal waters have as low cl b ratios as 1 and b concentrations as high as 10 ppm the cause is either b degassing of the magmatic intrusive heat source or phase separation in the producing aquifer some low temperature waters

laser probe 40ar 39ar studies of the peace river shocked l6 chondrite abstract samples of matrix and melt glass from the shocked l6 chondrite peace river have been subjected to 40ar 39ar analysis using both stepped heating and localised outgassing by a laser probe stepped heating studies of three distinct samples of matrix gave indistinguishable and unusually well defined low temperature 40ar 39ar plateaux corresponding to an age of 450 30 ma in an attempt to investigate whether or not this plateau age is meaningful i e the time of a major collision event involving the parent body or is an artefact resulting from partial degassing during the fragmentation of the parent body which commenced the exposure of peace river to cosmic rays 40 ma ago we have used a laser probe to analyse ar from single 80 m diameter laser pits which release gas from a few micrograms of sample on this scale no areas have ages younger than the plateau age supporting the view that it is not an artefact measurements on the melt glass gave variable and meaningless ages in some cases greater than the age of the solar system due to retention of 40ar and loss of k during melting followed by rapid quenching this observation indicates the danger of attempts to date impact melt glass directly the observation that argon has been retained by the glass and lost by the matrix can be understood in terms of a range of plausible annealing histories

high pressure polymorphs in yamato 790729 l6 chondrite and their significance for collisional conditions shock pressure recorded in yamato y 790729 classified as l6 type ordinary chondrite was evaluated based on high pressure polymorph assemblages and cathodoluminescence cl spectra of maskelynite the host rock of y 790729 consists mainly of olivine low ca pyroxene plagioclase metallic fe ni and iron sulfide with minor amounts of phosphate and chromite a shock melt vein was observed in the hostrock ringwoodite majorite akimotoite lingunite tuite and xieite occurred in and around the shock melt vein the shock pressure in the shock melt vein is about 14 23 gpa based on the phase equilibrium diagrams of high pressure polymorphs some plagioclase portions in the host rock occurred as maskelynite sixteen different cl spectra of maskelynite portions were deconvolved using three assigned emission components centered at 2 95 3 26 and 3 88 ev the intensity of emission component at 2 95 ev was selected as a calibrated barometer to estimate shock pressure and the results indicate pressures of about 11 19 gpa the difference in pressure between the shock melt vein and host rock might suggest heterogeneous shock conditions assuming an average shock pressure of 18 gpa the impact velocity of the parent body of y 790729 is calculated to be 1 90 km s 1 the parent body would be at least 10 km in size based on the incoherent formation mechanism of ringwoodite in y 790729

formation of high pressure minerals in shocked l6 chondrite yamato 791384 constraints on shock conditions and parent body size we have studied the high pressure phases observed in yamato 791384 l6 chondrite host meteorite mainly consists of olivine pyroxenes and plagioclase glass mineral fragments observed in the veins and the vein margin region of the host meteorite were partially or totally transformed into high pressure phases ringwoodite majorite akimotoite naalsi3o8 hollandite and jadeite matrix of the shock vein contains majorite pyrope solid solution the spatial distribution indicates that high pressure phases are present in the shock veins and host rocks adjacent to the shock veins investigation of the high pressure phases revealed that in y791384 fragments and adjacent matrix were subjected to pressures around of 18 23 gpa and the vein experienced temperatures around 2300 c during the shock event ringwoodite lamellae were observed in the host olivine adjacent to the vein kinetic investigation for ringwoodite lamellar growth in olivine indicates that the shocked meteorite experienced the pressure for at least 4 s such long duration of the pressure pulse indicates that the size of the parent body was greater than 10 km

pseudotachylyte controversy fact or friction high speed slip experiments performed on westerly granite using friction welding apparatus reveal that comminution is an essential precursor to melting by friction observations of slip surfaces via analytical scanning electron microscopy sem document the following sequence of events occurring in 2 s with increasing velocity up to 2 m s fracture progressive comminution surface melting of mineral fragments fragment to fragment adhesion and finally production of a fragment laden melt supported suspension explosive dehydration and melting of the epidote group mineral allanite indicates that temperatures of at least 1000 c were realized at the interface this is corroborated by calculation of the temperature rise for the known operating conditions contrary to earlier proposals these results show that comminution and frictional melting are complementary and not mutually exclusive processes depending on the velocity shear stress displacement relations prevailing during frictional slip rocks produced in seismogenic zones can be predominantly comminuted wall rock or fragment melt mixes pseudotachylytes

mobility and fluxes of major minor and trace metals during basalt weathering and groundwater transport at mt etna volcano sicily abstract the concentrations and fluxes of major minor and trace metals were determined in 53 samples of groundwaters from around mt etna in order to evaluate the conditions and extent of alkali basalt weathering by waters enriched in magma derived co 2 and the contribution of aqueous transport to the overall metal discharge of the volcano we show that gaseous input of magmatic volatile metals into the etnean aquifer is small or negligible being limited by cooling of the rising fluids basalt leaching by weakly acidic co 2 charged water is the overwhelming source of metals and appears to be more extensive in two sectors of the s sw paterno and e zafferana volcano flanks where out flowing groundwaters are the richest in metals and bicarbonate of magmatic origin thermodynamic modeling of the results allows to evaluate the relative mobility and chemical speciation of various elements during their partitioning between solid and liquid phases through the weathering process the facts that rock forming minerals and groundmass dissolve at different rates and secondary minerals are formed are taken into account at mt etna poorly mobile elements al th fe are preferentially retained in the solid residue of weathering while alkalis alkaline earth and oxo anion forming elements as se sb mo are more mobile and released to the aqueous system transition metals display an intermediate behavior and are strongly dependent on either the redox conditions mn cr v or solid surface related processes v zn cu the fluxes of metals discharged by the volcanic aquifer of etna range from 7 0 10 3 t a th to 7 3 10 4 t a na they are comparable in magnitude to the summit crater plume emissions for a series of elements na k ca mg u v li with lithophile affinity but are minor for volatile elements basalt weathering at mt etna also consumes about 2 1 10 5 t a of magma derived carbon dioxide equivalent to ca 7 of contemporaneous crater plume emissions the considerable transport of some metals in etna s aquifer reflects a particularly high chemical erosion rate evaluated at 2 3 10 5 t a enhanced by the initial acidity of magmatic co 2 rich groundwater

assessment of groundwater circulation in la gomera aquifers canary islands spain from their hydrochemical features la gomera canary islands spain does not show water scarcity like other islands of the archipelago however the study of its aquifers is paramount as nearly 60 of the water supplies are covered with spring water according to the currently accepted hydrogeological model la gomera presents an upper aquifer consisting of perched groundwater bodies below this hydrogeological unit the general saturated zone or basal groundwater is placed the model also establishes the presence of flows through them many perched groundwater bodies are located under garajonay national park where most of the springs are found therefore if upper and lower aquifers are truly connected and new wells are built the new extractions could affect garajonay ecosystems with the aim of identifying spring groups and related potential areas of water transfer hydrochemical and statistical analyses principal component analysis and cluster analysis have been applied this study shows the great compositional variability of groundwaters precluding the identification of spring groups hydrochemical patterns and therefore the transfer areas with no possibility of assessing the potential impact of a water demand increase on the garajonay national park ecosystems from the present data only the springs belonging to group ii of the cluster analysis could indicate a transfer area the lack of conclusive results could be due to 1 great compositional variability of volcanic materials 2 unequal influence of marine aerosols 3 irregular distribution of rainfall 4 different grades of soils development and 5 the occurrence of partially disconnected water bodies giving as a result a complex hydrogeological system

l chondrite asteroid breakup tied to ordovician meteorite shower by multiple isochron 40ar 39ar dating radiochronometry of l chondritic meteorites yields a rough age estimate for a major collision in the asteroid belt about 500 myr ago fossil meteorites from sweden indicate a highly increased influx of extraterrestrial matter in the middle ordovician 480 myr ago an association with the l chondrite parent body event was suggested but a definite link is precluded by the lack of more precise radiometric ages suggested ages range between 450 30 myr and 520 60 myr and can neither convincingly prove a single breakup event nor constrain the delivery times of meteorites from the asteroid belt to earth here we report the discovery of multiple 40ar 39ar isochrons in shocked l chondrites particularly the regolith breccia ghubara that allow the separation of radiogenic argon from multiple excess argon components this approach applied to several l chondrites yields an improved age value that indicates a single asteroid breakup event at 470 6 myr fully consistent with a refined age estimate of the middle ordovician meteorite shower at 467 3 1 6 myr according to a geologic time scale 2004 our results link these fossil meteorites directly to the l chondrite asteroid destruction rapidly transferred from the asteroid belt the increased terrestrial meteorite influx most likely involved larger projectiles that contributed to an increase in the terrestrial cratering rate which implies severe environmental stress

shock metamorphism of ordinary chondrites a revised petrographic classification of progressive stages of shock metamorphism of ordinary chondrites is proposed six stages of shock s1 to s6 are defined based on shock effects in olivine and plagioclase as recognized by thin section microscopy the characteristic shock effects of each shock stage are s1 unshocked sharp optical extinction of olivine s2 very weakly shocked undulatory extinction of olivine s3 weakly shocked planar fractures in olivine s4 moderately shocked mosaicism in olivine s5 strongly shocked isotropization of plagioclase maskelynite and planar deformation features in olivine and s6 very strongly shocked recrystallization of olivine sometimes combined with phase transformations ringwoodite and or phases produced by dissociation reactions s6 effects are always restricted to regions adjacent to melted portions of a sample which is otherwise only strongly shocked in stages s3 to s6 localized melting results from stress and temperature peaks which locally deviate from the equilibration shock pressure due to differences in shock impedance these melting effects are a opaque melt veins shock veins b melt pockets with interconnecting melt veins c melt dikes and d troilite metal deposits in fractures based on a critical evaluation of data from shock recovery experiments a shock pressure calibration for the six shock stages is proposed which defines the s1 s2 s2 s3 s3 s4 s4 s5 and s5 s6 transitions at 5 5 10 15 20 30 35 and 45 55 gpa respectively whole rock melting and formation of impact melt rocks or melt breccias occurs at about 75 90 gpa the symbol for the shock stage may be used in combination with the symbol for the petrologic type to abbreviate the complete classification of a chondrite e g h5 s3 we propose this new shock classification and pressure calibration system to replace previous systems which are out of date with respect to the pressure calibration nominally restricted to l chondrites and based on incomplete and in part illdefined sets of shock effects we have classified seventy six ordinary chondrites using the new classification system and conclude the following 1 1 shock effects and the sequence of progressively increasing degrees of shock metamorphism are very similar in h l and ll groups differences in the frequency distribution of shock stages are relatively minor e g l chondrites appear to have the largest fraction with stages s5 and s6 this suggests that the collisional histories of the h l and ll parent bodies were similar 2 2 petrologic type 3 chondrites are deficient in stages s4 to s6 and with increasing petrologic type the frequency of stages s4 to s6 increases we suggest that the more porous and volatile rich type 3 chondrites are subject to melting at a lower shock pressure than the nonporous chondrites of higher petrologic type volatiles trapped in pores cause shock induced dispersal of the shocked and melted material into small particles which are not expected to survive as meteorites 3 3 stage s3 is the most abundant in nearly all petrologic types 4 4 at shock pressures in excess of about 35 gpa s5 and s6 4he and 40ar are almost completely lost pressures below 10 gpa s1 and s2 do not cause noble gas losses

boron sr o and h isotope geochemistry of groundwaters from mt etna sicily hydrologic implications combined b o h and sr isotopic studies of groundwaters from mt etna provide new constraints on their origin and the consequences of fluid rock interaction within this hydrologic system variations in d 18 o 29 7 to 27 2 and d d 262 to 223 mainly lie along the regional meteoric water line and suggest that most waters originated as local precipitation however small shifts in d 18 o and variable 87 sr 86 sr 0 70355 to 0 70879 and d 11 b 25 2 to 125 8 indicate that subsequent interactions occurred between the fluids and local rocks high b cl ratios in all samples seemingly preclude direct involvement of seawater in the hydrologic system despite the proximity to the coast and in some samples elevated 87 sr 86 sr and d 11 b two general end member water types are recognized on the basis of their chemistry these apparently are produced by interactions of local meteoric waters with the dominant reservoir rocks either basaltic lavas of etna or the underlying sediments respectively high d 11 b in the sediment hosted end member points to a significant marine carbonate contribution subsequent mixing between these or similar end members produced a range of intermediate composition groundwaters certain anomalous water compositions require the presence locally of a distinct component with high b and moderate d 11 b ca 110 but relatively low 87 sr 86 sr an anthropogenic source for this component is plausible one unusual sample has b and sr isotopic compositions similar to the other volcanic rock hosted waters but anomalously high cl content that likely reflects local magmatic outgassing near this sampling locality in general this study indicates that groundwater b and sr isotopic compositions are rock dominated these data provide useful constraints on the origin and evolution of groundwaters copyright 2000 elsevier science ltd

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

development and spatial distribution of soils on an active volcano mt etna sicily abstract as a large active volcano mt etna presents a complex soil forming environment with a spatial diversity of lava flow age tephra deposition local climate and agriculture following a review of previous published research on etna s soils this paper analyses physical and chemical data for 23 profiles between 120 m and 1030 m elevation on all flanks of the volcano with the aim of characterising the soils and determining the extent to which the chief controls on their nature and geography may be identified soils are sampled across a chronosequence of lava flows dating from 72 yr to between 28 ka and 42 ka bp which occur in conditions of diverse land use and local climate ages of flows 3000 yr are only broadly constrained the majority of soils comprise mostly tephra chief soil processes inferred have been identified in previous published research on mt etna accumulation of soil organic matter rapid loss of na and production of fine grained materials particularly those inferred to be of short range order other developments are soil structural formation and evidence of increasing soil mesofaunal activity despite the complexity of environmental diversity and spatial variation in tephra deposition a number of soil properties including material

anatomy of black veins in zagami clues to the formation of high pressure phases abstract black melt veins in the martian basaltic meteorite zagami were investigated using analytical transmission electron microscopy with the goal to constrain the mechanisms and ptt conditions that result in the formation of high pressure phases therein our study reveals the existence of a number of high pressure minerals stishovite k and na ca rich hollandites akimotoite silicate ilmenite as well as amorphous grains of silicate perovskite composition crystals of a ferro magnesian silicate titanite with a low ca content have been identified for the first time the veins formed by rapid shear melting and solidified in extremely short times as a consequence the vein melt could not homogeneously mix and it partially preserves the chemical heterogeneity of precursor minerals accounting for the large diversity of high pressure minerals most of the tiny phases directly crystallized from the melt under high pressure at very high temperatures silicate perovskite probably amorphized upon decompression and evolved at its grain boundaries by solid state diffusion toward the lower pressure assemblage wustite stishovite not only do these observations help to understand the formation of high pressure phases in shock events but they also provide clues to the mineralogical complexity that can be expected in planetary mantles

tracing the circulation of groundwater in volcanic systems using the 87sr 86sr ratio application to mt etna abstract the 87 sr 86 sr ratio was investigated in groundwater circulating in the volcanic edifice of mt etna in order to estimate the possible contribution of deep brines circulating in the sedimentary basement samples from 14 sites were collected and analyzed for their chemical composition and sr isotope ratios while the most common approach of coupling 87 sr 86 sr ratios with the concentration of dissolved sr is not effective in distinguishing between the deep brine and seawater contributions we suggest that the sr cl ratio is a useful complementary parameter that needs to be considered when attempting to clearly identify the sr sources the obtained data indicate that the sr isotope signature of groundwater is determined by the volcanics hosting the aquifer the volcanic isotopic signature is modified by very small amounts of brines 87 sr 86 sr ratio typical of sedimentary environments but only at sites where the groundwater circulates almost in contact with the sedimentary basement conversely the contribution of seawater is completely ruled out since this should produce a higher concentration of chloride the proposed approach is potentially very effective for tracing the circulation of groundwater not only at mt etna but also at volcanic edifices that overlie a bedrock with different 87 sr 86 sr ratios as well as at volcanic islands where freshwater overlies seawater

assessing the impact of natural and anthropogenic activities on groundwater quality in coastal alluvial aquifers of the lower liaohe river plain ne china abstract the lower liaohe river plain lrp is an economically and ecologically important area situated on an alluvial plain where anthropogenic activities are very intensive field investigations were conducted in the lrp and 15 water quality parameters surveyed at 216 wells during september and october of 2009 and 2010 these showed significant variation in the hydrochemistry of groundwater throughout the plain a piper plot was used to identify the major geochemical processes occurring in the entire plain principal components analysis pca was used to identify various underlying natural and anthropogenic processes that created these distinct water types the stuyfzand classification was used to subdivide and interpret the complex groundwater hydrochemistry of the liaohe river delta five principal components pcs were extracted in terms of pca which can be invoked to explain 82 of the total variance in water quality parameters the pca results can be categorized by five major factors 1 holocene transgression and mixing 2 surface water infiltration 3 multi factor processes 4 rainfall and agricultural fertilizer contamination and 5 geogenic f enrichment this study demonstrates that the great variation of groundwater hydrochemistry in the lrp should be attributed to both natural and anthropogenic processes

groundwater geochemistry of a nitrate contaminated agricultural site groundwater samples were collected from several soil depths down to 50 m below soil surface to investigate vertical profiles of no3 and hydrogeochemical characteristics of the experimental site the experimental site is located in the shimabara city nagasaki japan where nitrate contamination in groundwater is severe due to intensive agricultural production a transition zone regarding dissolved ions was found between specific depths caused by differences in the permeability of soil layers though no3 concentration decreased significantly in the transition zone the entire soil depth exceeded permissible levels 50 mg l 1 for drinking purposes comparing the temporal no3 fluctuation above the transition zone with that of the below distinct fluctuations were observed depending on sampling campaign high rainfall amounts typically lead to initial decrease in no3 concentration for the shallow groundwater after some time however increase in no3 concentration occurred due to leaching of accumulated no3 in the soil matrix this indicated that temporal no3 fluctuation is mainly controlled by natural impact and occurring crop system results of principal component analysis suggested that application of chemical fertilizers nh4 2so4 nh4no3 and kcl dissolution of minerals feldspar calcite and dolomite and ion exchange are the predominant factors resulting in the observed vertical groundwater chemistry the relative magnitude of these three principal component scores changed across the transition zone below the transition zone groundwater geochemistry reflected application of nh4no3 and kcl fertilizer and dissolution of albite and orthoclase less

two distinct assemblages of high pressure liquidus phases in shock veins of the sixiangkou meteorite shock produced complex veins including earlier and later veins are identified in the sixiangkou l6 chondrite the early vein is intersected by the late vein and consists of coarse grained aggregates of ringwoodite majorite and lingunite and fragments of olivine pyroxene plagioclase metal and troilite as well as a fine grained matrix of garnet ringwoodite metal and troilite the late vein mainly consists of a fine grained matrix of garnet magnesiowustite metal and troilite as well as a small amount of coarse grained aggregates the amount of fine grained matrix suggests that the late vein was nearly completely melted whereas the early vein underwent partial melting both fine grained assemblages of garnet plus ringwoodite in the early vein and garnet plus magnesiowustite in the late vein are liquidus phases crystallized from shock induced melt based on our understanding of the liquidus assemblages the late vein experienced a higher pressure and temperature than the early vein

hydrochemistry of a complex volcano sedimentary aquifer using major ions and environmental isotopes data dalha basalts aquifer southwest of republic of djibouti in the republic of djibouti horn of africa fractured volcanic aquifers are the main water resources the country undergoes an arid climate alluvial aquifers exist in the wadis intermittent streams valleys and in relation with volcanic aquifers form complex volcano sedimentary systems due to increasing water demands groundwater resources are overexploited and require a rigorous management this paper is focused on the dalha basalts aquifer located in the dikhil area southwest of djibouti this aquifer is of vital importance for this area hydrochemical data and isotopic tracers 18o and 2h were used to identify factors and phenomena governing the groundwater s mineralization the piper diagram shows complex water types results from multivariate statistical analyses highlight three water families according to their locations 1 groundwater characterized by low ionic concentrations located at the wadis zones 2 groundwater characterized by moderate salinity and 3 highly mineralized waters mainly flowing in the eastern and central part of the study area in volcanic aquifers results from scatter plots especially na versus cl and br versus cl suggest that the origin of more saline waters is not from dissolution of halite the 18o and 2h data indicate that the groundwater flowing in the alluvial aquifer is of meteoric origin and fast percolation of rainwater occurs in the volcanic aquifers these findings provide a preliminary understanding of the overall functioning of this complex volcano sedimentary system additional investigations pumping tests numerical modeling are in progress to achieve a more comprehensive understanding of this system

assessment of the impact of anthropogenic activities on the groundwater hydrology and chemistry in tarsus coastal plain mersin se turkey using fuzzy clustering multivariate statistics and gis techniques summary tarsus coastal plain tcp is an economically and ecologically important area situated in between the fertile fluvio deltaic plains of two rivers delicay and tarsus mersin se turkey where anthropogenic activities agricultural industrial and domestic are very intense twenty four water quality parameters were surveyed at 193 groundwater and 10 surface water sites during august 2008 the objective was to characterize the physico chemical properties of groundwaters in tcp assess the impact of anthropogenic activities on the groundwater hydrology and chemistry and identify the major hydrogeochemical processes occurring in the area groundwater samples were grouped into hydrochemically distinct and spatially continuous four water classes i e c1 c2 c3 and c4 using the fuzzy c means fcm clustering method where membership values were interpolated using the ordinary kriging technique principal components analysis pca was used to decipher various underlying natural and anthropogenic processes creating these distinct water classes four principal components pcs were extracted in pca which explained more than 73 of the total variance in water quality major factors responsible for the variations in chemistries of water classes are identified as 1 water rock interaction and nitrate contamination 2 salinization by seawater intrusion and evaporite dissolution 3 geogenic anthropogenic cr fe and mn and 4 anthropogenic zn pollution overexploitation of the aquifer is clearly evident especially at settlements located near the coastal zone where the water table is lowered 2 5 m below the sea level salinization is well known in the area and is attributed not only to seawater intrusion but also to dissolution of evaporitic series from the handere formation hydrochemical evidence also suggest that in the area subsurface paleo river channels and the deposits infilling the ancient lagoon area within quaternary recent alluvial deposits act as significant hydrological features where preferential groundwater flow occurs along them

thermal modeling of shock melts in martian meteorites implications for preserving martian atmospheric signatures and crystallization of high pressure minerals from shock melts the distribution of shock melts in four shergottites having both vein and pocket geometry has been defined and the conductive cooling time over the range 2500 c to 900 c calculated isolated 1 mm2 pockets cool in 1 17 s and cooling times increase with pocket area an isolated vein 1 7 mm in northwest africa nwa 4797 cools to 900 c in 4 5 s interference between thermal haloes of closely spaced shock melts decreases the thermal gradient extending cooling times by a factor of 1 4 to 100 this is long enough to allow differential diffusion of ar and xe from the melt small pockets 1 mm2 lose 2 2 ar and 5 2 xe during cooling resulting in a small change in the ar xe ratio of the dissolved gas over that originally trapped with longer cooling times there is significant fractionation of xe from ar and the ar xe ratio increases rapidly the largest pockets show less variation of ar xe and likely preserve the original trapped gas composition considering all of the model calculations even the smallest isolated pockets have cooling times greater than the duration of the pressure pulse i e 0 01 s the crystallization products of these shock melts will be unrelated to the peak shock pressure experienced by the meteorite

neogene arc continent collision in sabah northern borneo malaysia abstract the neogene evolution of sabah can be interpreted in terms of an arc continent collision initiated during early middle miocene time and followed by intraplate shortening the latter being active in this area at the present day the volcanic arc of late oligocene middle miocene age is imbricated with melanges and thrust northwestward on a polyphase deformed turbiditic sequence of late cretaceous middle miocene age crocker range intraplate shortening is seen in the thrusting and folding offshore sabah along the palawan north borneo trench and also by broad open folds and strike slip faulting in the previously sutured terranes this collision can either be interpreted as the final stage of southward subduction of the hypothetical proto south china sea or the result of back thrusting of the sulu volcanic arc resulting from the subduction of the celebes sea toward the north

climatic and tectonic controls on weathering in south china and indochina peninsula clay mineralogical and geochemical investigations from the pearl red and mekong drainage basins 1 results of clay mineralogy major element geochemistry and sr and nd isotopes in 93 argillaceous samples collected from drainage basins of the pearl red and mekong rivers reveal different degrees of chemical weathering in southeast asia despite similar climate conditions across these regions the kaolinite illite ratio illite chemistry index and illite crystallinity can be used as indicators of chemical weathering intensity these mineralogical proxies combined with the k2o na2o cao molar ratio chemical index of alteration cia and weathering trends observed from major element results indicate intensive silicate weathering in the pearl river basin moderate to intensive in the mekong river basin and moderate in the red river basin although a significant modification of epsilon nd 0 values in our riverine sediments during chemical weathering and transport is unlikely sr 87 sr 86 ratios are controlled by various states of chemical weathering of high sr minerals such as plagioclase rich in na and ca with a linear decrease trend from the pearl mekong to red river basins our results suggest that it is not the warm climate with heavy monsoon precipitation but tectonics playing the most significant role in controlling weathering and erosion processes in south china and indochina peninsula strong physical erosion caused by tectonic activities and river incision along the eastern margin of the tibetan plateau and along the red river fault system is responsible for high contents of primary minerals in the lowlands of red and mekong river basins

a large shock vein in l chondrite roosevelt county 106 evidence for a long duration shock pulse on the l chondrite parent body a large shock induced melt vein in l6 ordinary chondrite roosevelt county 106 contains abundant high pressure minerals including olivine enstatite and plagioclase fragments that have been transformed to polycrystalline ringwoodite majorite lingunite and jadeite the host chondrite at the melt vein margins contains olivines that are partially transformed to ringwoodite the quenched silicate melt in the shock veins consists of majoritic garnets up to 25 m in size magnetite maghemite and phyllosilicates the magnetite maghemite and phyllosilicates are the terrestrial alteration products of magnesiowustite and quenched glass this assemblage indicates crystallization of the silicate melt at approximately 20 25 gpa and 2000 c coarse majorite garnets in the centers of shock veins grade into increasingly finer grained dendritic garnets toward the vein margins indicating increasing quench rates toward the margins as a result of thermal conduction to the surrounding chondrite host nanocrystalline boundary zones that contain wadsleyite ringwoodite majorite and magnesiowustite occur along shock vein margins these zones represent rapid quench of a boundary melt that contains less metal sulfide than the bulk shock vein one dimensional finite element heat flow calculations were performed to estimate a quench time of 750 1900 ms for a 1 6 mm thick shock vein because the vein crystallized as a single high pressure assemblage the shock pulse duration was at least as long as the quench time and therefore the sample remained at 20 25 gpa for at least 750 ms this relatively long shock pulse combined with a modest shock pressure implies that this sample came from deep in the l chondrite parent body during a collision with a large impacting body such as the impact event that disrupted the l chondrite parent body 470 myr ago

fractional crystallization of olivine melt inclusion in shock induced chondritic melt vein abstract the formation of ringwoodite wadsleyite and majorite from their parental low pressure polymorphs in melt veins in chondritic meteorites is usually interpreted to be the result of shock induced solid state phase transformation formation and survival of individual mineral melt enclaves in the chondritic high pressure melt was not considered a viable possibility we report evidence for melting of individual large olivine fragments entrained in melt veins their survival as melt enclaves in the chondritic melts and their subsequent fractional crystallization at high pressures and temperatures the fractionally crystallized olivine melt enclaves appear to be ubiquitous in chondrites in contrast ca poor pyroxene fragments in the same veins and ca poor pyroxene in chondrules entrained do not show any sign of melting texture and compositions of olivine fragments are indicative of fractional crystallization from individual olivine melts alone fragments of original unzoned olivine fa 24 26 melted and melts subsequently fractionally crystallized to mg rich wadsleyite fa 6 10 and mg poor ringwoodite fa 28 33 with a compositional gap of 26 mol fayalite in contrast compositions of ringwoodite and wadsleyite that emerged from solid sate phase transformations are identical to that of parental olivine thus erasing any source of enigma the olivine monomineralic melts barely show any signs of mixing with the chondritic liquid prior to or during their individual fractional crystallization our findings demonstrate that the formation of high pressure minerals during shock events in asteroids also results from melting and fractional crystallization from some individual mineral melts that barely mixed with the chondritic melt host a mechanism previously not recognized or accepted

coherent and subsequent incoherent ringwoodite growth in olivine of shocked l6 chondrites abstract pervasive replacement of original olivine grains by ringwoodite adjacent to a shock melt vein of yamato 791384 l6 chondrite was observed with a feg sem in these olivines we observed three distinct olivine ringwoodite textures arranged in a spatially successive arrangement from the wall of the shock melt vein into the olivine grains 1 polycrystalline ringwoodite 2 oriented several sets of ringwoodite lamellae and 3 oriented single lamellae tem images show that the polycrystalline and oriented several sets of lamellae parts consist of polycrystalline ringwoodite indicating that phase transformation from olivine to ringwoodite is controlled by incoherent growth mechanism on the other hand the set of oriented single lamellae consists of thin ringwoodite platelets

deep south china sea circulation 1 the analysis of an updated monthly climatology of observed temperature and salinity from the u s navy generalized digital environment model reveals a basin scale cyclonic circulation over the deep south china sea scs the cyclonic circulation lies from about 2400 m to the bottom the boundary current transport of the cyclonic circulation is around 3 0 sv our results suggest that the cyclonic circulation is mainly forced by the luzon overflow with bottom topography playing an important role the structures of potential temperature salinity and potential density in the deep scs are consistent with the existence of the cyclonic circulation specifically low salinity water is found in the interior region west of luzon island and surrounded by saline pacific water in boundary current regions to the north west and southwest our results show the potential density distribution and the corresponding cyclonic circulation in deep scs are primarily controlled by salinity variations in the deep basin

variability of the path of the kuroshio ocean current over the past 25 000 years the kuroshio current is the strong northwestern component of the subtropical north pacific ocean gyre and advects a large amount of heat from the tropics to northern mid latitudes the kuroshio has bimodal stationary flow patterns with small and large meander paths east of central japan1 2 which switch on annual and decadal timescales3 4 these switches seem to be caused by changes in current velocity and volume transport of the north equatorial current that are associated with variations in the trade wind intensity in the eastern equatorial north pacific ocean5 6 here we present alkenone derived sea surface temperature records at multicentennial resolution from sediment cores from the nishishichitou ridge off central japan these 25 000 year records show that the kuroshio path has also fluctuated on millennial timescales this variability resembles that of the subtropical high pressure of the north pacific reconstructed from terrestrial pollen distributions water levels in north american lakes and marine micropalaeontological records7 together these data indicate that climate variability off central japan over the past 25 000 years may be part of a circum pacific phenomenon reflecting the rate of subtropical surface circulation in the north pacific ocean

prediction of some weathering trends of plutonic and volcanic rocks based on thermodynamic and kinetic considerations abstract the exposed crust consists mainly of plagioclase 35 quartz 20 k feldspar 11 volcanic glass 12 biotite 8 and muscovite 5 quartz is a resistate thus feldspars and glass represent approximately 75 percent of the labile minerals the weathering characteristics of these constituents are summarized in the context of thermodynamic mass balance and kinetic considerations experimentally determined release rate constants were used to predict the proportions of ca na and k released by feldspars of plutonic rocks granites to gabbros to weathering solutions the chemical weathering trends of the weathered residues calculated from the kinetic data conform closely to the initial trends observed in some recent weathering profiles demonstrating the accuracy of the predictions since the weathering of feldspars is controlled by processes that should not change through geological time the relative release rates of ca na and k from the feldspars of granitic rocks can be calculated for future and past episodes of continental weathering experimentally determined release rate constants are not available for a wide range of volcanic glass compositions but the limited data indicate that compositional trends are predictable in weathering profiles developed on volcanic rocks the kinetic data available for rhyolitic glasses accurately predict the initial weathering trends observed in a recent rhyolite weathering profile

metastability of enstatite in deep subducting lithosphere olivine and mg fe sio3 pyroxene the most abundant minerals in the earth s upper mantle are believed to transform to high pressure phases at 400 km depth1 5 the possible metastable persistence of olivine to greater depths in some subduction zones with consequences for the origin of deep focus earthquakes and the dynamics of subduction has been discussed extensively6 14 but the role of other mantle minerals has not been considered we report here an experimental study of the kinetic behaviour of the magnesian pyroxene enstatite mgsio3 at upper mantle conditions we find that whereas forsterite mg olivine mg2sio4 transforms rapidly to phase at 1 200 c and 16 gpa the transformation of enstatite to phase plus stishovite on the same timescale requires much higher temperatures at lower temperatures enstatite transforms directly to the ilmenite structure but only at pressures greater than 20 gpa enstatite should therefore persist metastably to greater depths than olivine in subduction zones transforming directly to the ilmenite structure the enstatite ilmenite transformation is accompanied by a large decrease in volume which should increase the stresses in subducting slabs change the buoyancy forces that drive subduction and might also contribute to the origin of deep focus earthquakes

south china sea fluvial sediments an introduction the south china sea offers a special research opportunity for earth scientists because of its location and its well preserved terrigenous sediments wang and li 2009 as the largest one of the marginal seas separating asia from the pacific the south china sea functions as a natural laboratory for study of land sea interactions because of its unique source to sink record of fluvial sediments the south china sea receives more than 600 million tons of detrital sediments annually from numerous rivers including world s largest rivers such as the pearl the red and the mekong fig 1

source to sink transport processes of fluvial sediments in the south china sea the south china sea offers an excellent case for studying source to sink transport processes of fluvial sediments among the global marginal seas this study synthesizes existing clay mineralogical and geochemical data from similar to 1500 samples from the seafloor and surrounding rivers deepwater mooring observation results and high resolution glacial cyclic clay mineralogy records from six high quality sediment cores source to sink sediment transport from the river mouth to the continental shelf and then to the abyssal basin is investigated at two time scales modern process and late quaternary glacial cycles the results firstly show the high diversity of clay mineralogical and geochemical compositions in riverbed surface sediments surrounding the south china sea e g dominant illite and chlorite in taiwan overwhelming majority of smectite in luzon dominant kaolinite in south china and similar amounts of the four clay mineral species in red and mekong river systems the formation of these fluvial sediments through chemical weathering in surrounding drainage systems is controlled principally by the east asian monsoon climate with warm temperature and high precipitation and subordinately by tectonic activity and specific lithological character the basin wide distribution of clay mineral assemblages combined with neodymium and strontium isotopic compositions reflects strong provenance control and differential settling effects the differential settling of kaolinite in slightly saline and proximal regions relative to smectite in more saline and distal regions is well demonstrated in the south china sea through combining clay mineralogical distributions on the seafloor with observed oceanic current systems the modern transport pathways can be well established e g in the northern south china sea illite and chlorite from taiwan are mainly carried by contour currents with the strong influence of mesoscale eddies high resolution sediment dynamic analysis for the late quaternary reveals different sediment transport patterns in the northern western and southern south china sea when the land sea configuration dramatically changed during glacial conditions in the north the terrigenous dispersal is mainly controlled by provenance supply and oceanic current transport in the west the clay mineral assemblage reflects variations of the prevailing surface current influenced by monsoon winds in the south the clay mineral input indicates intensive chemical weathering during interglacial periods and strengthened physical erosion during glacial periods the transport of terrigenous sediments since the last glaciation is quantitatively reconstructed through studying two deepwater sediment cores located in the northern south china sea the relative contributions from three provenances south china luzon and taiwan highlight their distinct variability over the last 28 ka implying that the southward shift of the inter tropical convergence zone itcz at 16 ka bp caused an increased sediment contribution from south china the intensified influence of the kuroshio current intrusion controls more efficient westward transport of luzon sediments and the stronger deepwater current transports taiwan sourced sediments further westward from the last glaciation to the holocene c 2015 elsevier b v all rights reserved

groundwater mixing in a heterogeneous multilayer aquifer driven by geogenic co2 fluxes evidence from chemical and isotopic composition of ferrarelle waters riardo plain southern italy abstract the successful management of carbon in the earth s crust is critical for mitigating the increase of anthropogenic co2 in the atmosphere carbon capture and storage ccs requires an understanding of the behavior of carbon in the crust and the development of robust monitoring techniques to constrain the movement mechanisms and pathways for any potential co2 leakage here we examine an aquifer from the riardo plain campania region southern italy which serves as a suitable natural analogue for co2 migration to the critical zone i e shallow crust and aquifers and as a case study to evaluate the geochemical processes that occur when co2 saturated fluids mix with freshwater in shallow aquifers we investigate the behavior of various geochemical constituents major and trace elements 18o h2o 13c dic and rn content water from this area has a high degree of mineralization ec 2500 3000 s cm high hco3 2 5 g l is saturated with respect to caco3 and is enriched in alkali ions e g na k the high degree of mineralization occurs in groundwater that discharges from the basal aquifer of the roccamonfina volcanic edifice 6 km nw with vast co2 inputs that promote host rock leaching superficial volcanic aquifers are recharged by fresh meteoric precipitation when groundwater flows from carbonates at the edge of the plain to aquifers hosted in the southeastern slope of the roccamonfina volcano the presence of normal faults in this area permits natural upwelling of co2 rich groundwater which locally mixes with shallow freshwater present within the upper volcanic succession significant r 0 8 linear correlations between conservative elements suggest that groundwater geochemistry is dominated by a mixture of two main endmembers i deep mineralized waters and ii shallow diluted waters the intrusion of freshwater to volcanic aquifers induces oxidation leading to adsorption of select elements e g as and ba onto fe oxyhydroxide precipitates within these aquifers geochemical modeling suggests that co2 saturation approaches 3 g l which agrees with direct measurements of co2 flux we conclude that our conceptual geochemical model helps to constrain mixing of co2 with freshwater and to diagnose the secondary geochemical processes that influence aqueous geochemistry within co2 influenced groundwater

geochemistry of gases and waters discharged by the mud volcanoes at paterno mt etna italy approximately 20 km south of mt etna craters at the contact between volcanic and sedimentary formations three mud volcanoes discharge co2 rich gases and na cl brines the compositions of gas and liquid phases indicate that they are fed by a hydrothermal system for which temperatures of 100 150 c were estimated by means of both gas and solute geothermometry the hydrothermal system may be associated with co2 rich groundwaters over a large area extending from the central part of etna to the mud volcanoes numerous data on the he ch4 co2 composition of the gases of the three manifestations sampled over the past 5 years indicate clearly that variations are due to separation processes of a co2 rich gas phase from the liquid the effects of these processes have to be taken into account in the interpretation of the monitoring data collected for the geochemical surveillance of etna volcano

monsoon evolution and tectonics climate linkage in asia an introduction peter d clift1 ryuji tada2 hongbo zheng3 school of geosciences meston building university of aberdeen aberdeen ab24 3ue uk department of earth and planetary science university of tokyo science building 1 7 3 1 hongo tokyo 113 0033 japan institute of surficial geochemistry school of earth science and engineering nanjing university 22 hankou road nanjing people s republic of china

roots of etna volcano in faults of great earthquakes abstract results from several seismic methods allow us to sketch the deep structure of etna and its ionian margin under etna a volume of high velocity material is found in a structurally high position the emplacement of this suggests spreading of the surrounding medium just offshore down to the east normal faults penetrate through the upper crust the deeper crustal structure beneath appears upwarped from the basin towards etna juxtaposed with the crust of sicily a thinner crust reaches from the ionian basin under etna and the mantle is upwarped in such a structure magma can then be viewed as a melted lens capping a mantle upwarp at shallow depth rather than in an intracrustal chamber this reduces the conflict between estimates of its volume from excess output of volatiles and short residence times a link in time is indicated between volcanic and seismic activity at a large scale over the millennium the reported ends of episodes of high output rates of magma are followed by the reported occurrences of magnitude 7 earthquakes which caused destruction in southeastern sicily several steep active normal fault have been imaged to a depth of 10 km the crust up to 30 km offshore of the cities of catania and augusta which may be fault planes for such large earthquakes they expand and prolongate the system of the timpe faults on the eastern flank of etna thus linking large scale tectonics offshore with the volcano etna developed together with normal faulting upwarp and spreading during the recent evolution of the former ionian subduction activation of the material at depth at the lateral edge of the slab by vertical motion with extension above could produce the peculiar type of etna magmatism

geochemical characterization of surface waters and groundwater resources in the managua area nicaragua central america abstract this paper reports new geochemical data on dissolved major and minor constituents in surface waters and ground waters collected in the managua region nicaragua and provides a preliminary characterization of the hydrogeochemical processes governing the natural water evolution in this area the peculiar geological features of the study site an active tectonic region nicaragua depression characterized by active volcanism and thermalism combined with significant anthropogenic pressure contribute to a complex evolution of water chemistry which results from the simultaneous action of several geochemical processes such as evaporation rock leaching mixing with saline brines of natural or anthropogenic origin the effect of active thermalism on both surface waters e g saline volcanic lakes and groundwaters as a result of mixing with variable proportions of hyper saline geothermal na cl brines e g momotombo geothermal plant accounts for the high salinities and high concentrations of many environmentally relevant trace elements as b fe and mn in the waters at the same time the active extensional tectonics of the managua area favour the interaction with acidic reduced thermal fluids followed by extensive leaching of the host rock and the groundwater release of toxic metals e g ni cu the significant pollution in the area deriving principally from urban and industrial waste water probably also contributes to the aquatic cycling of many trace elements which attain concentrations above the who recommended limits for the elements ni 40 g l and cu 10 g l limiting the potential utilisation of lake xolotlan for nearby managua

environmental impact of magmatic fluorine emission in the mt etna area universita degli studi di palermo italy istituto nazionale di geofisica e vulcanologia sezione di palermo unione europea fondo sociale europeo

akimotoite in the tenham meteorite crystal chemistry and high pressure transformation mechanisms the transformation of pyroxene to its high pressure polymorph akimotoite mgsio3 ilmenite type structure is documented in the shock induced melt veins of the l6 tenham chondrite four textural relationships between pyroxene and akimotoite are observed in former pyroxene grains entrained in the shear melt vein and in pyroxene grains attached to the wall of the melt vein in one of the entrained enstatite grains the transformation to akimotoite is partial one third of the grain is transformed to a polycrystalline aggregate of akimotoite with a scalloped interface with enstatite akimotoite fe0 4mg1 24ca0 07na0 12al0 14 si1 963al0 037 o6 is slightly enriched in ca cao 1 74 al and na with respect to enstatite cao 0 71 narrow bands of polycrystalline akimotoite with three crystallographic orientations and a chemical composition similar to the surrounding enstatite intersect the other part of the grain in a second grain entrained in the shear melt vein tablets of akimotoite are interwoven with a pyroxene glass with a lower na and fe content and a higher mg content compared to the adjacent akimotoite this pyroxene glass is probably the product of mg fe sio3 perovskite amorphization polycrystalline akimotoite is also formed at the expense of enstatite at the vein wall of the shear melt vein in that case akimotoite is also enriched in ca cao 2 85 na nao 1 72 and al al2o3 4 14 all these observations suggest that akimotoite is mainly formed by solid state transformation of former pyroxenes with subsequent diffusion of calcium aluminum and sodium from the chondritic melt of the shear melt vein finally the first complete x ray diffraction pattern of natural akimotoite is presented

occurrence and mobility of major and trace elements in groundwater from pristine volcanic aquifers in jeju island korea abstract major and trace elements in groundwater from basaltic aquifers in pristine conditions were investigated in a volcanic island to evaluate sources sinks and mobility of elements over a wide range of mineralization conditions with total dissolved solids from 50 mg l to 3400 mg l groundwater was highly undersaturated with respect to primary silicate minerals indicating that dissolution of basaltic rocks may continue under conditions with precipitation of calcite and secondary silicates evolution of b cl ratio in groundwater from marine aerosols to basaltic rocks showed that the ratio could be used as a conservative tracer for interactions between water and basaltic rocks relative mobility rm of elements calculated using the concentrations of elements in the local basaltic rocks and those in groundwater showed that mobility decreased in the order of b rb na k mg ca mo v si sr sc p u zn pb cr cu ba ni ti mn al fe co th indicating that oxyanion forming elements and alkali metals had the highest mobility compared to average rm v had decreased mobility and fe and mn had increased mobility in anoxic groundwater while v mo and u had higher mobility in oxic alkaline water the sources of v cr cu and zn in rocks were estimated using the partition coefficients between minerals and basaltic melt and the disparity between sources and mobility indicated that sinks are more important for controlling the concentrations of these elements in groundwater than the contents in the rocks principal component analysis pca of hydrogeochemical parameters in groundwater produced three principal components pc which represent dissolution of basaltic rocks without significant attenuation of released solutes higher degree of water rock interactions resulting in oxic alkaline conditions and attenuation of zn and cu in higher ph respectively spatial distribution of pcs revealed that groundwater with elevated concentrations of mobile elements was concentrated in the southwestern area and that concentrations of v and cr were more scattered which is likely to be controlled by ph and redox states of groundwater as well as degree of water rock interactions

characterizing unsaturated flow from packed scoriated lapilli application to strombolian cone hydrodynamic behavior summary over the past 30 years numerous studies have been carried out into groundwater behavior in volcanic areas with particular attention being paid to unsaturated volcanic tuffs the volcanic formations of the chaine des puys massif central france have long been regarded as valuable sources of fresh water and many aquifers associated with volcanic flows have been tapped for domestic water supply or as sources of bottled mineral water it has often been postulated that these volcanic flows are recharged by groundwater from the volcanic cones located upstream although no efforts have been made to validate this theory we tested the physical basis of this hypothesis by characterizing the unsaturated hydrodynamic properties of the packed lapilli and scoria that form the most important constituents of the strombolian cones in this area the model derived from the results of the characterization experiments was compared with data obtained from a field site the unsaturated properties of this site puy de louchadiere strombolian cone are discussed qualitatively and in terms of memory effect further investigations are now needed to determine the exact behavior of the strombolian cone and to produce complete models of the saturated and unsaturated zones of the aquifer system

heterogeneous mineral assemblages in martian meteorite tissint as a result of a recent small impact event on mars the microtexture and mineralogy of shock melts in the tissint martian meteorite were investigated using scanning electron microscopy raman spectroscopy transmission electron microscopy and synchrotron micro x ray diffraction to understand shock conditions and duration distinct mineral assemblages occur within and adjacent to the shock melts as a function of the thickness and hence cooling history the matrix of thin veins and pockets of shock melt consists of clinopyroxene ringwoo dite stishovite embedded in glass with minor fe sulfide the margins of host rock olivine in contact with the melt as well as entrained olivine fragments are now amorphosed silicate perovskite magnesiowustite or clinopyroxene magnesiowustite the pressure stabilities of these mineral assemblages are 15 gpa and 19 gpa respectively the 200 lm wide margin of a thicker mm size up to 1 4 mm shock melt vein contains clinopyroxene olivine with central regions comprising glass vesicles fe sulfide spheres fragments of host rock within the melt are polycrystalline olivine after olivine and tis sintite glass after plagioclase from these mineral assemblages the crystallization pressure at the vein edge was as high as 14 gpa the interior crystallized at ambient pressure the shock melts in tissint quench crystallized during and after release from the peak shock pressure crystallization pressures and those determined from olivine dissociation therefore represent the minimum shock loading shock deformation in host rock minerals and complete transformation of plagioclase to maskelynite suggest the peak shock pressure experienced by tissint p 29 30 gpa these pressure estimates support our assessment that the peak shock pressure in tissint was significantly higher than the minimum 19 gpa required to transform olivine to silicate perovskite plus magnesiowustite small volumes of shock melt 100 lm quench rapidly 0 01 s whereas thermal equilibration will occur within 1 2 s in larger volumes of melt 1 mm 2 the apparent variation in shock pressure recorded by variable mineral assemblages within and around shock melts in tissint is consistent with a shock pulse on the order of 10 20 ms combined with a longer duration of post shock cooling and complex thermal history this implies that the impact on mars that shocked and ejected tissint at 1 ma was not exceptionally large

tuite γ ca3 po4 2 formed by chlorapatite decomposition in a shock vein of the suizhou l6 chondrite tuite ca3 po4 2 was first discovered as the high pressure phase of whitlockite in shock veins of the suizhou l6 meteorite this study reports the finding of tuite in a shock vein of the same suizhou chondrite as a product of decomposition of chlorapatite where it coexists with coarse grained ringwoodite majorite lingunite fine grained majorite pyrope solid solution and magnesiowustite moreover we also successfully synthesized tuite with a multianvil apparatus from chlorapatite at 15 gpa and 1573 k over 24 h both natural and synthetic tuite crystals were examined by means of optical microscopy scanning electron microscope electron microprobe analysis x ray diffraction and raman spectroscopy our results suggest that the na2o mgo and cl contents in natural tuite may serve as good indicators for distinguishing the precursor phosphate mineral chlorapatite or whitlockite

evidence for multiple dynamic events and subsequent decompression stage recorded in a shock vein we investigated a shock vein of the yamato 791384 l6 chondrite to clarify the nature and sequence of the dynamic processes that resulted from the shock events the chondritic host rock of y 791384 mainly consists of olivine fa24 25 low ca pyroxene fs18 22 albitic feldspar an9 10ab84 86or5 7 troilite and metallic fe ni the shock vein contains majorite or majorite pyropess and magnesiowustite minor jadeite as high pressure polymorphs two different dynamic events were recorded in the shock vein the majorite grain contained vitrified mg fe sio3 perovskite inclusions the mg fe sio3 perovskite was crystallized from a chondritic melt and is a remnant of a first dynamic event the majorite and magnesiowustite were also crystallized directly from a chondritic melt but induced by a second dynamic event the pressure condition for the first and second dynamic events would be 24 gpa and 22 gpa respectively pervasive feather shaped olivine fa16 nucleated on the magnesiowustite and majorite this feather shaped olivine is evidence for rapidly grown olivine from the melt related to the shock event phase relations deduced from high pressure melting experiments of the allende meteorite and peridotite indicate that the magnesiowustite and majorite olivine pair cannot coexist at equilibrium condition the disequilibrium assemblage reflects a decompression stage these features demonstrate the complexity of events during a natural dynamic process

volcanic plume fingerprint in the groundwater of a persistently degassing basaltic volcano mt etna abstract the chemical composition of the groundwater at mt etna was investigated in order to determine the extent to which the persistent plume affects the chemical composition of circulating waters samples from 31 springs and wells were collected during june and july 2014 and analyzed for their chemical compositions the content of dissolved elements derives from the bulk deposition wet and dry deposition at the recharge areas as well as from the weathering of volcanic rocks during the infiltration and transport of groundwater in its early phase the chemical weathering of volcanic rocks and ashes is promoted by the acid rain that characterizes the area and subsequently by the huge amount of deep magmatic carbon dioxide co 2 coming up through the volcanic edifice and dissolving in the water the high content of chlorine is mainly derived from interactions between the plume and rainwater while the total alkalinity can be completely ascribed to the dissociation of carbonic acid h 2 co 3 after the hydration of co 2 the relative contributions of plume derived elements weathering and co 2 driven weathering has been computed for each element in addition the comparison between the chemical compositions of the bulk deposition and of groundwater provides a new understanding about the mobility of volatile elements the proposed approach has revealed that the persistent plume strongly affects the chemical composition of groundwater at mt etna and probably also at other volcanoes characterized by huge open conduit degassing activity

diffusive loss of argon in response to melt vein formation in polygenetic impact melt breccias many planetary surfaces in the solar system have experienced prolonged bombardment with each impact new rocks can be assembled that incorporate freshly generated impact melts with fragments of older rocks some breccias can become polygenetic containing multiple generations of impact melt products and can potentially provide important insights into the extensive bombardment history of a region however the amount of chronological information that can be extracted from such samples depends on how well the mineral isotopic systems of geochronometers can preserve the ages of individual melt generations without being disturbed by younger events we model the thermal evolution of impact melt veins and the resulting loss of ar from k bearing phases common in impact melt breccias to assess the potential for preserving the 40ar 39ar ages of individual melt generations our model results demonstrate that millimeter scale clast free melt veins cause significant heating of adjacent host rock minerals and can cause detectable ar loss in contact zones that are generally thinner than and at most about the same thickness as the vein width the incorporation of cold clasts in melt veins reduces the magnitudes of heating and ar loss in the host rocks and ar loss can be virtually undetectable for sufficiently clast rich veins quantitative evidence of the timing of impacts as measured with the 40ar 39ar method can be preserved in polygenetic impact melt breccias particularly for those containing mm scale bodies of clast bearing melt products

dissolved constituents and sr isotopes in river waters from a mountainous island the danshuei drainage system in northern taiwan abstract taiwan is a typical active orogenic belt situated at the collision boundary between the eurasian continental plate and the philippine sea plate dissolved major and trace constituents as well as sr and sr isotopes in river waters collected from the danshuei river basin in northern taiwan have been studied to evaluate chemical weathering processes the results of principal component analysis show that the ion sources in these river waters can be categorized into 3 major components chemical weathering seasalt contribution and local anthropogenic input the chemical weathering is the most dominant factor that contributes about 85 of total variances significantly increased na cl and ca cl as well 87 sr 86 sr were observed in most upper stream samples the na cl and ca cl ratios in the dahan stream however are much higher than the shindien stream even though average rainfall is stronger in the shindien drainage basin chemical evidence from river waters supports less intense weathering in the region selective dissolution of secondary calcites explains the observed high ca cl sr cl and ca na in the dahan stream these results highlight the potential importance of tectonic factors such as uplift and physical erosion in studying chemical weathering in an active orogenic belt the variations of 87 sr 86 sr in the danshuei river are quite large reflecting some strata that released sr most of the upstream waters exhibit more radiogenic 87 sr 86 sr 0 713243 0 714338 due to weathering of ambient low grade metamorphic rocks 0 71678 0 72216 the distributions of cl sr and 87 sr 86 sr in the main stream were affected by somewhat conservative mixing with sources varing between ambient rocks and seasalt in the upper dahan stream heavy 87 sr 86 sr ratios were coincident with large deviations of na cl from the average seawater value as high as 40 the degree of chemical weathering in ambient rocks plays a dominant role in affecting the distribution of sr and 87 sr 86 sr in the danshuei river this isotopic characteristic makes 87 sr 86 sr an invaluable tracer for studying source mixing migration pathways and chemical weathering in an active orogenic belt

iron partitioning in a pyrolite mantle and the nature of the 410 km seismic discontinuity pyrolite1 is a hypothetical mixture of distinct minerals which iswidely believed to represent the composition of the earth s mantle the main pressure induced phase transformations of the olivine component of pyrolite occur at about 13 5 gpa to and 24 gpa to mgsio3 rich perovskite magnesiowustite 2 3 which are thought to be responsible for the seismic discontinuities at 410 and 660 km depths in the mantle recent seismological studies however have demonstrated that the 410 km seismic discontinuity is sharper in some areas than that expected from the to transformation in mantle olivine with a fixed composition4 5 6 7 moreover some mineral physics studies suggest that the seismic velocity jump at the 410 km discontinuity is inconsistent with that associated with the to transformation in olivine8 9 here we present a phase equilibria study of a material having pyrolite composition at pressures of 6 16 gpa we found that the iron content in olivine changes significantly with increasing pressure as a result of the formation of a relatively iron rich majorite phase at these pressures this variation in iron content can overcome or at least reduce both of the above difficulties encountered with the pyrolite model of mantle composition by showing that the component mineral systems cannot be treated as separate

co2 output and δ13c co2 from mount etna as indicators of degassing of shallow asthenosphere an estimated average co2 output from etna s summit craters in the range of 13 3 mt a has recently been determined from the measured so2 output and measured co2 so2 molar ratios to this amount the co2 output emitted diffusely from the soil 1 mt a and the amount of co2 dissolved in etna s aquifers 0 25 mt a must be added data on the solubility of co2 in etnean magmas at high temperature and pressure allow the volume of magma involved in the release of such an amount of this gas to be estimated this volume of magma 0 7 km3 a is approximately 20 times greater than the volume of magma erupted annually during the period 1971 1995 on the basis of c isotopic data of co2 collected in the etna area and of new hypotheses on the source of mediterranean magmas significant contributions of co2 from non magmatic sources to the total output from etna are unlikely such large outputs of co2 and also of so2 from etna could be due to an anomalously shallow asthenosphere beneath the volcano that allows a continuous escape of gases toward the surface even without migration of magma

high pressure phases in a shock induced melt vein of the tenham l6 chondrite constraints on shock pressure and duration abstract the microtexture and mineralogy of a 580 m wide melt vein in the tenham l6 chondrite were investigated using field emission scanning electron microscopy and transmission electron microscopy to better understand the shock conditions the melt vein consists of a matrix of silicate plus metal sulfide grains that crystallized from immiscible melts and sub rounded fragments of the host chondrite that have been entrained in the melt and transformed to polycrystalline high pressure silicates the melt vein matrix contains two distinct textures and mineral assemblages corresponding to the vein edge and interior the 30 m wide vein edge consists of vitrified silicate perovskite ringwoodite akimotoite majorite with minor metal sulfide the 520 m wide vein interior consists of majorite magnesiowustite with irregular metal sulfide blebs although these mineral assemblages are distinctly different the pressure stabilities of both assemblages are consistent with crystallization from similar pressure conditions the melt vein edge crystallized at about 23 25 gpa and the vein interior crystallized at about 21 25 gpa this relatively narrow pressure range suggests that the melt vein either crystallized at a constant equilibrium shock pressure of 25 gpa or during a relatively slow pressure release using a finite element heat transfer program to model the thermal history of this melt vein during shock we estimate that the time required to quench this 580 m wide vein was 40 ms because the entire vein contains high pressure minerals that crystallized from the melt the shock pressure duration was at least 40 ms using a synthetic hugoniot for tenham and assuming that the sample experienced a peak shock pressure of 25 gpa near the impact site we estimate that the tenham parent body experienced an impact with collision velocity 2 km s based on a one dimensional planar impact model we estimate that the projectile size was 150 m in thickness

increased contribution of terrigenous supply from taiwan to the northern south china sea since 3 ma seismic profiles provide evidence that there has been strong transport by deep water bottom currents and drift deposition on the northern slope of the south china sea earlier geochemical studies suggest that the drift sediments originated primarily from taiwan however the transport process history and origin of the deep water bottom deposition in the northern south china sea on both glacial interglacial and tectonic time scales remain unclear here we show new high resolution records of clay minerals grain size and mass accumulation rate mar of terrigenous materials from ocean drilling program odp site 1144 together with trace element concentrations in siliciclastic sediments from odp site 1146 combined with other published data we find that the primary source for sediments at odp sites 1144 1148 since 3 ma is from taiwan and not from pearl river as previously thought before 3 ma however sediment source to odp sites 1146 and 1148 was mainly from the pearl river increased contribution of terrigenous supply from taiwan to the northern south china sea since similar to 3 ma may be related to the formation of the taiwan orogen and strengthening of deep water bottom current transport in the northern south china sea variations in clay mineralogy and sedimentology at odp site 1144 located on a sediment drift shows strong glacial interglacial cyclicity this suggests that bottom current deposition is highly dependent on sea level fluctuations which control the terrigenous supply to the deep sea c 2010 elsevier b v all rights reserved

preliminary geochemical evidence of groundwater contamination in coral islands of xi sha south china sea geochemical data on dissolved major minor and trace constituents in groundwater samples from xi sha coral islands paratas islands reveal the main processes responsible for their geochemical evolution multivariate statistical analysis indicates four sources of solutes 1 seawater intrusion due to limited groundwater recharge 2 leaching of heavy metals from imported granite soil 3 leaching of toxic elements such as as due to guano soil erosion and historical phosphatic guano mining and 4 local and regional contamination characterized by high loadings of cu ag and hg although process 1 dominates the geochemical characteristics of the groundwater process 4 indicates the significant role of anthropogenic impact by local e g cu and regional e g hg sources such contamination in groundwater will potentially impose adverse effects on the fragile ecosystem of the coral islands it is necessary to monitor microorganisms associated with human feces in the nearshore water column as well as nutrient levels in coastal waters in order to further assess the impact of human activities on the ecosystem of these islands

chemical and isotopic characterization of the gases of mount etna italy abstract in the period 1990 1995 43 samples of dissolved gases in groundwaters wells springs and drainage galleries and 64 samples of free gases fumaroles bubbling and soil gases from the mount etna area were collected and analysed isotopic analyses were also carried out of both the carbon of the co 2 in free gases and dissolved inorganic carbon dic in the waters the chemical composition of the gases depends on the relative abundances of three interacting components these are gases of 1 atmospheric origin enriched in o 2 and n 2 present almost exclusively in dissolved gases 2 deep origin enriched in co 2 prevalent in the majority of cases and 3 more superficial origin enriched in ch 4 prevailing in peripheral areas the isotopic composition of co 2 carbon confirms its mantle origin with either thermometamorphic co 2 contributions or modifications due to interaction with hot waters

selenium mobilization in soils due to volcanic derived acid rain an example from mt etna volcano sicily abstract the significant amounts of selenium se emitted by volcanoes may have important impact on human health due to the narrow range between nutrition requirement and toxic effects for living organisms upon se exposure although soils play a key role in determining the level in food and water and thereby human health little is known about the behaviour of se in volcanic soils in this work we evaluated the se release during rainwater soil interaction under controlled conditions using soils collected on the flanks of etna volcano and synthetic rain selenium concentrations in soil leachate solutions displayed a spatial distribution which cannot be explained by plume deposition total se soil concentrations or the presence of fe oxides instead al compounds and to a minor extent som were identified as the active phases controlling the selenate mobilization during interaction with sulphate containing rainwater this shows the importance of soils as reactive interfaces selenium is mobilized when volcanic derived acid rain interacts with poorly developed soils close to the crater this geogenic process might influence the chemical composition of groundwater and as a result human health

multivariate statistical analysis of geochemical data as indicative of the hydrogeochemical evolution of groundwater in a sedimentary rock aquifer system summary the study of groundwater hydrogeochemistry of the paleozoic basses laurentides sedimentary rock aquifer system in quebec produced a large geochemical dataset groundwater samples were collected at 153 sites over a 1500 km2 study area and analyzed for major and minor ions the large number of data can lead to difficulties in the integration interpretation and representation of the results two multivariate statistical methods hierarchical cluster analysis hca and principal components analysis pca were applied to a subgroup of the dataset to evaluate their usefulness to classify the groundwater samples and to identify geochemical processes controlling groundwater geochemistry this subgroup consisted of 144 samples and 14 parameters ca2 mg2 na k hco 3 cl so 4 2 fe2 mn2 br sr2 f ba2 hs seven geochemically distinct clusters c1 c7 resulted from the hca samples from clusters c3 c4 c6 and c7 are mostly located in preferential recharge areas the majority of these samples have ca mg hco3 recharge groundwater c3 c6 c7 and na hco3 evolved groundwater c4 samples from the other three clusters c1 c2 c5 are characteristic of an aquifer system under confined conditions the majority of these samples have na hco3 evolved groundwater c1 c5 and na cl ancient groundwater that exhibits elevated concentrations in br c2 in addition to recognizing the importance of hydrogeological conditions on groundwater geochemistry the distribution of clusters also showed the importance of the geological formations on minor and trace elements such as fe2 mn2 sr2 f and ba2 the first five components of the pca account for 78 3 of the total variance in the dataset component 1 is defined by highly positive loadings in na cl and br and is related to groundwater mixing with champlain sea water and solute diffusion from the marine clay aquitard the high positive loadings in ca2 and mg2 of component 2 suggest the importance of dissolution of carbonate rocks in this aquifer system from their characteristic loadings the first two components are defined as the salinity and hardness components respectively components 3 5 are related to more local and geological effects the integration of the hca and the pca with conventional classification of groundwater types as well as with the hydrogeological and geological contexts allowed the division of the region into four main geochemical areas providing an improved regional picture of the aquifer system dynamics and hydrogeochemical evolution of groundwater the following factors were recognized as influencing the evolution of groundwater identified in every geochemical area 1 geological characteristics including sedimentary rock type and till mineralogy 2 hydrogeological characteristics represented by the level of confinement and the hydraulic gradient and 3 the geological history including the latest glaciation and the champlain sea invasion with its integrated approach this hydrogeochemical study contributes to the characterization and understanding of complex groundwater flow systems and provides an example of the long term geochemical evolution of hydrogeological systems after a major perturbation in this case seawater invasion

experimental approach to generate shock veins in single crystal olivine by shear melting a shock experiment has been devised to produce large shear in a single crystal sample of olivine the recovered sample exhibits macroscopic shear faults resembling shock veins in ordinary chondrites examination with transmission electron microscopy reveals a high density of dislocations in the bulk olivine the shear faults appear as thin veins containing small grains of olivine and pockets of glass the microstructure and composition of the material in the veins point to fractional crystallization of a melt an order of magnitude calculation is consistent with the idea that the veins were produced by shear melting these results support the view that shock veins in meteorites are the result of shear heating rather than of pressure heterogeneities

role of an impermeable layer in controlling groundwater chemistry in a basaltic aquifer beneath an agricultural field jeju island south korea abstract hydrochemical data major cations and anions and trace metals such as fe mn and v of groundwater n 144 were collected from 15 pre existing wells in the gosan area along the southwestern coast of jeju island south korea between january and october 2010 these were used to investigate the spatio temporal variability of groundwater quality in a basaltic aquifer beneath an agricultural field in the western part of the study area an impermeable clay rich layer gosan formation overlies the basaltic aquifer prohibiting direct recharge from rainwater infiltration and allowing a shallow perched aquifer to form above the formation robust principal component analysis robpca was performed to investigate the hydrochemical characteristics twenty seven outlying samples were separated from the total dataset among these 17 samples reflected seawater effects and seven samples reflected abnormally high impacts from agricultural contamination for the rest regular observations n 117 and a good leverage point robpca showed that principal component pc 1 effectively distinguishes uncontaminated water from those samples reflecting agricultural contamination variables with positive pc 1 loadings tds ca mg no 3 so 4 and cl indicate agricultural contamination while negative pc 1 loadings ph na k hco 3 and v possibly indicate basalt weathering samples with chemistry controlled by agricultural contamination are restricted to the eastern part of the study area while uncontaminated water is predominantly observed in the western part where the gosan formation occurs such a distinct spatial pattern indicates that overall groundwater quality is regulated by the occurrence of the impermeable formation groundwater samples from wells near the edge of the gosan formation show seasonal fluctuations in water quality with factor scores that indicates uncontaminated water in the dry season january to april and agricultural contamination in the wet season may to october this suggests that groundwater below the marginal part of the impermeable layer is seasonally contaminated by a temporal extension of the pollution front during the wet season even though the impermeable layer plays a role as a natural barrier to protect groundwater from the infiltration of surface contaminants this study also shows the advantage of robpca to successfully identify spatio temporal variation of groundwater quality in an area where diverse hydrochemical processes are coexisting and anormalous samples occur

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

arsenic and fluorine in the etnean volcanics from biancavilla sicily italy environmental implications mineralogical and geochemical studies were undertaken in the volcanic area of biancavilla catania italy with the aim of explaining the nature of the high as and f contents of the area s rocks as and f contents in soils and groundwater were also investigated the metasomatised benmoreite lavas show fluorine and arsenic concentrations up to about 3 000 and 1 000 mg kg respectively mineralogical analyses show that fluorine occurs mostly in fluoro edenite and apatite caf crystals both abundantly present in the altered rocks while as is exclusively attributed to the apatite caf crystals specifically arsenic was observed only at the borders of these apatite crystals leaching tests and sequential extraction procedures were carried out to evaluate the potential remobilisation of as and f by the mineral phases and the eventual risks induced by their spreading the results of the leaching tests suggest that as is almost totally associated with the easily reducible fraction and that it is released by the preferential dissolution of the arsenic enriched rims of apatite caf crystals in soils as concentration is relatively low about 15 mg kg on average while f ranges from 236 to 683 mg kg the underground waters supplying the town of biancavilla show as and f contents lower than the allowed limits for drinking water as 10 g l f 1 1 5 mg l the limited distribution of these rocks and the relatively limited mobilisation by the minerals both contribute to maintain low as and f values in soils and groundwaters despite the high values in metasomatised lava samples