vertical profile of artificial radionuclide concentrations in the central arctic ocean abstract the artificial radionuclides 90 sr 137 cs 238 pu 239 240 pu and 241 am have been measured in eight water samples collected in 1979 at intervals from surface to bottom through the ice at the lorex satellite camp ss near the north pole differences in the concentrations and ratios of these nuclides compared with values measured over time in the various water masses that flow into the arctic ocean can be used as semi independent checks on rates of flow to the lorex stations and on residence times in the arctic ocean an unexpected finding was that water labelled with low level liquid waste from the windscale plant on the irish sea is a major component of the 1500 m lorex sample and has reached there in no more than eight to ten years even from this one station in the polar ocean estimation of the inventories of the various radionuclides is good enough to emphasize the importance of horizontal advection of the various supply terms to the arctic

rare earth elements as indicators of groundwater environment changes in a fractured rock system evidence from fracture filling calcite rare earth element ree abundances in core samples from precambrian crystalline rocks at the samkwang mine site provide evidence of the solution chemistry involved in precipitation of calcite on fractures the rock types collected in core samples are mainly banded gneisses with mineral assemblages dominated by biotite k feldspar quartz and plagioclase calcite chlorite muscovite and sericite occur as secondary minerals with calcite being the main filling material in fractures in general the core samples from 4 boreholes are enriched in light ree lree and depleted in heavy ree hree with negative eu anomalies however positive eu anomalies also occur at specific depths within 3 boreholes variation of chondrite normalized ree patterns results from the fracture filling calcite in core samples calcite fracture fillings provide a record of paleo hydrology where eu has been reduced and selectively concentrated in the solutions from which calcite has precipitated

circulation phenomena and frontal dynamics of the norwegian coastal current after a short general description of the norwegian coastal current some recent investigations concerning its variability are reviewed the variability caused by meteorological effects and fresh water fluxes is shown to be the dominant feature the coastal current not only responds to local wind forcing but is also a signal channel of sea level variations in the north sea as a whole the variability at times manifests itself as mesoscale waves and eddies the subsurface frontal region is characterized by interleaving of coastal and atlantic water and strong mixing lateral and longitudinal frontal motions are dealt with in relation to plumes of brackish water from the fjords and outbreaks of brackish and or warm water masses from the skagerrak the inflow of atlantic water through the norwegian trench and the formation of deep and bottom water in skagerrak are discussed

controls on the geochemistry of rare earth elements along a groundwater flow path in the carrizo sand aquifer texas usa groundwater samples were collected along a groundwater flow path in the carrizo sand aquifer in south texas usa field measurements that included ph specific conductivity temperature dissolved oxygen do oxidation reduction potentials eh in mv alkalinity iron speciation and h2s concentrations were also conducted on site the geochemistry i e concentrations shale normalized patterns and speciation of dissolved rare element elements rees in the carrizo groundwaters are described as a function of distance along a flow path eh and other redox indicators i e do fe speciation h2s u and re indicate that redox conditions change along the flow path in the carrizo sand aquifer within the region of the aquifer proximal to the recharge zone groundwaters exhibit both highly oxidizing and localized mildly reducing conditions however from roughly 10 km to the discharge zone groundwaters are reducing and exhibit a progressive decrease in redox conditions dissolved ree geochemical behavior exhibits regular variations along the groundwater flow path in the carrizo sand aquifer the changes in ree concentrations shale normalized patterns and speciation indicate that rees are not conservative tracers with flow down gradient redox conditions ph and solution composite and adsorption modify groundwater ree concentrations fractionation patterns and speciation

trace elements in magnetite from massive iron oxide apatite deposits indicate a combined formation by igneous and magmatic hydrothermal processes iron oxide apatite ioa deposits are an important source of iron and other elements e g ree p u ag and co vital to modern society however their formation including the namesake kiruna type ioa deposit sweden remains controversial working hypotheses include a purely magmatic origin involving separation of an fe p rich volatile rich oxide melt from a si rich silicate melt and precipitation of magnetite from an aqueous ore fluid which is either of magmatic hydrothermal or non magmatic surface or metamorphic origin in this study we focus on the geochemistry of magnetite from the cretaceous kiruna type los colorados ioa deposit 350 mt fe located in the northern chilean iron belt los colorados has experienced minimal hydrothermal alteration that commonly obscures primary features in ioa deposits laser ablation inductively coupled plasma mass spectroscopy la icp ms transects and electron probe micro analyzer epma wavelength dispersive x ray wdx spectrometry mapping demonstrate distinct chemical zoning in magnetite grains wherein cores are enriched in ti al mn and mg the concentrations of these trace elements in magnetite cores are consistent with igneous magnetite crystallized from a silicate melt whereas magnetite rims show a pronounced depletion in these elements consistent with magnetite grown from an fe rich magmatic hydrothermal aqueous fluid further magnetite grains contain polycrystalline inclusions that re homogenize at magmatic temperatures 850 c smaller inclusions 500 ppm concentrations

geochemical and hydrogeochemical evolution of groundwater in ferdows area northeast of iran the chemical analysis of 19 water wells in ferdows area northeastern iran has been evaluated to determine the hydrogeochemical processes and ion concentration background in the region in the study area the order of cation and anion abundance is na ca2 mg2 k and cl so4 2 hco3 no3 respectively and the dominating hydrochemical types are na cl most metal concentrations in water depend on the mineral solubility and ph eh and salinity of the solution their ree concentrations showed excellent correlations with parameters such as tds and ph north american shale composite nasc normalized ree patterns are enriched in the hrees relative to the lrees for all groundwaters they all have positive eu anomalies eu eu 0 752 3 934 and slightly negative ce anomalies ce ce 0 019 1 057 reduction oxidation complexation desorption and re adsorption alter groundwater ree concentrations and fractionation patterns the positive eu anomalies in groundwaters are probably due to preferential mobilization of eu2 relative to the trivalent rees in the reducing condition

iron rich fragments in the yamansu iron deposit xinjiang nw china constraints on metallogenesis abstract volcanic rock hosted iron deposits are among the important iron ores in china however the nature of primary magma and petrogenesis associated with these iron ores remains controversial here we report iron rich fragments irf from the yamansu iron deposit in eastern tianshan mountains nw china which occurs in association with volcanic breccia submarine volcanic breccia and ignimbrite the irf is composed of five types including oligoclase iron oxide type oio oligoclase albite iron oxide type oaio albite iron oxide type aio albite k feldspar iron oxide type akio and k feldspar iron oxide type kio these fragments display typical volcanic fabric features such as porphyritic texture hyalopilitic texture of the groundmass and vesicles filled by minerals to form amygdales the feldspar phenocrysts of irf are dominantly albite the groundmass of irf consists of magnetite and feldspar the magnetite is distributed in between the feldspar laths and together display hyalopilitic texture which could be observed only in volcanic rocks the vesicles are filled with magnetite feldspar chlorite and calcite from the margin to the interior the irf has high si al fe ca ti na and k contents and low mg content the average total fe is 26 wt the magnetite is mostly titanium vanadium magnetite with the tio2 content ranging up to 4 86 wt and v2o3 content up to 3 20 wt the irf probably came from iron rich melts and represent the products of the fenner magma evolution the basaltic magma evolved into the fe na rich residual melts by crystallization under low oxygen fugacity condition in a closed magma chamber after intruding into the shallow crust the fe na rich residual melts were emplaced in hypabyssal environments or erupted generating the orebodies or providing the material source for the generation of the high grade iron ores which were subsequently enriched by the late stage hydrothermal fluids

groundwater geochemistry in the meshkinshahr basin of ardabil province in iran the chemical analysis of 59 water wells in meshkinshar area ardabil province nw of iran has been evaluated to determine the hydrogeochemical processes and ion concentration background in the region the dominated hydrochemical types are na so4 ca hco3 na hco3 and na cl in the whole area based on the total hardness the groundwater is soft according to electrical conductivity and sodium adsorption ratio the most dominant classes are c1 s1 c2 s1 and c3 s1 the major ion concentrations are below the acceptable level for drinking water the groundwater salinity hazard is medium to high but the na hazard is low to medium and in regard of irrigation water the quality is low to medium so the drainage system is necessary to avoid the increase of toxic salt concentrations

mineralogy fluid inclusions and isotopes of the cihai iron deposit eastern tianshan nw china implication for hydrothermal evolution and genesis of subvolcanic rocks hosted skarn type deposits abstract most skarn deposits are closely related to granitoids that intruded into carbonate rocks the cihai 100 mt at 45 fe is a deposit with mineral assemblages and hydrothermal features similar to many other typical skarn deposits of the world however the iron orebodies of cihai are mainly hosted within the diabase and not in contact with carbonate rocks in addition some magnetite grains exhibit unusual relatively high tio 2 content these features are not consistent with the typical skarn iron deposit different hydrothermal and or magmatic processes are being actively investigated for its origin because of a lack of systematic studies of geology mineral compositions fluid inclusions and isotopes the genetic type ore genesis and hydrothermal evolution of this deposit are still poorly understood and remain controversial the skarn mineral assemblages are the alteration products of diabase three main paragenetic stages of skarn formation and ore deposition have been recognized based on petrographic observations which show a prograde skarn stage garnet clinopyroxene disseminated magnetite a retrograde skarn stage main iron ore stage massive magnetite amphibole epidote ilvaite and a quartz sulfide stage quartz calcite pyrite pyrrhotite cobaltite overall the compositions of garnet clinpyroxene and amphibole are consistent with those of typical skarn fe deposits worldwide in the disseminated ores some magnetite grains exhibit relatively high tio 2 content 1 wt which may be inherited from the diabase protoliths some distinct chemical zoning in magnetite grains were observed in this study wherein cores are enriched in ti and magnetite rims show a pronounced depletion in ti the textural and compositional data of magnetite confirm that the cihai fe deposit is of hydrothermal origin rather than associated with iron rich melts as previously suggested fluid inclusions study reveal that the prograde skarn garnet and pyroxene formed from high temperature 520 600 c moderate to high salinity 8 1 23 1 wt nacl equiv and 46 wt nacl equiv fluids massive iron ore and retrograde skarn assemblages amphibole epidote ilvaite formed under hydrostatic condition after the fracturing of early skarn fluids in this stage had lower temperature 220 456 c and salinity 8 4 16 3 wt nacl equiv fluid inclusions in quartz sulfide stage quartz and calcite also record similar conditions with temperature range from 128 to 367 c and salinity range from 0 2 to 22 9 wt nacl equiv oxygen and hydrogen isotopic data of garnet and quartz suggest that mixing and dilution of early magmatic fluids with external fluids e g meteoric waters caused a decrease in fluid temperature and salinity in the later stages of the skarn formation and massive iron precipitation the 18 o values of magnetite from iron ores vary between 4 1 and 8 5 which are similar to values reported in other skarn fe deposits such values are distinct from those of other iron ore deposits such as kiruna type and magmatic fe ti v deposits worldwide taken together these geologic geochemical and isotopic data confirm that cihai is a diabase hosted skarn deposit related to the granitoids at depth

chemical characteristics of groundwater in parts of mountainous region alvand hamadan iran eighty seven groundwater samples have been collected from a mountainous region alvand iran for hydrochemical investigations to understand the sources of dissolved ions and assess the chemical quality of the groundwater most water quality parameters are within world health organization acceptable limits set for drinking water the least mineralized water is found closest to the main recharge zones and the salinity of water increased towards the north of the basin the most prevalent water type is ca hco3 followed by water types ca no3 ca cl ca so4 and mg hco3 the ca no3 water type is associated with high nitrate pollution agricultural and industrial activities were associated with elevated level of no3 mineral dissolution weathering of evaporites dominates the major element hydrochemistry of the area chemical properties of groundwater in alvand region are controlled both by natural geochemical processes and anthropogenic activities

temporal and spatial trends in the distribution of 137cs in surface waters of northern european seas a record of 40 years of investigations abstract the distribution of anthropogenic 137 cs in surface waters of the ne atlantic ocean resulting from discharges from european nuclear reprocessing plants the chernobyl accident and global fallout has shown decreasing concentrations in most regions in the past 2 decades in proportion to the lessening of its release rates from the sellafield and la hague reprocessing plants in contrast concentrations increased significantly in the baltic sea in 1986 as a result of the chernobyl accident the average 137 cs concentrations in surface water have been estimated for the year 2000 to be 60 50 bq m 3 for the irish sea 3 1 for the celtic sea 2 1 1 2 for the english channel 4 2 for the north sea 50 20 for the baltic sea 2 1 for the norwegian sea 2 4 0 5 for the barents sea and 4 1 bq m 3 for the kara sea on the basis of time series data the corresponding effective half lives of 137 cs in surface water have been estimated to be 4 1 years for the irish sea 2 1 for the celtic sea 1 2 0 5 for the english channel 3 1 for the north sea 13 2 for the baltic sea 4 1 for the norwegian sea 5 1 for the barents sea and 13 4 years for the kara sea the mean transit times of water masses have been estimated to be 0 5 0 1 year from the irish sea to the north channel 2 0 2 years to the north of scotland 2 5 0 2 to the east coast of england 3 0 5 to the southern north sea 4 0 5 to the central and eastern north sea 1 5 0 2 to the celtic sea 2 0 2 to the english channel 5 1 to the baltic sea 4 5 0 5 to the norwegian sea 5 1 to the barents sea and 6 1 years to the kara sea

composition and evolution of ore fluids in a magmatic hydrothermal skarn deposit the chemistry of brine vapor and low salinity fluid inclusions measured by proton induced x ray emission from the bismark skarn deposit mexico is consistent with an evolving magmatic hydrothermal system with no evidence for external fluid inputs the results support a model that invokes early phase separation of magmatic fluids into brine and vapor two phase field at high temperature and lithostatic pressure followed by the entrapment of a low salinity magmatic fluid one phase field at lower temperature and hydrostatic pressure the early brine and vapor inclusions contain high pb and zn concentrations and low cu however the vapor contains significantly more cu than the brine and was likely transported as a sulfur complex the fluid phase changes observed and behavior of cu are comparable to those of porphyry cu systems the later low salinity fluid at bismark represents a distinct pulse of magmatic fluid with a high k ca ratio in which base metals including cu were transported by chloride complexes paragenetic relationships and variations in the relative concentrations of cu pb and zn suggest that this fluid was primarily responsible for ore deposition the relative cu pb and zn concentrations in fluid inclusions at bismark are consistent with those measured from base metal ores in high temperature carbonate replacement deposits throughout mexico and suggest that the bulk metal budget of these deposits is primarily controlled by magmatic hydrothermal fluids deficient in cu

methane fluxes in marine sediments quantified through core analyses and seismo acoustic mapping bornholm basin baltic sea abstract methane is a terminal product of anaerobic degradation of organic matter in subsurface marine sediments depleted of reactive oxidants the depth and age of the sediment where sulfate is depleted determines the extent of methane production relative to the burial of organic carbon we aimed to understand how this methane production is controlled and distributed in an apparently uniform sediment basin we combined seismo acoustic surveys and geochemical analyses of sediment cores to explore the distribution of methane fluxes in brackish marine mud deposits of the bornholm basin southern baltic sea geophysical mapping revealed the depth distribution of a the thickness of the holocene organic rich mud layer overlaying organic poor postglacial clay and b the upper boundary of methane gas bubbles trapped in the holocene sediment by correlating these two parameters with the methane distributions in sediment cores from 44 stations we developed algorithms to estimate and map at high spatial resolution the diffusive methane fluxes in the 75 95 m deep and 4000 km2 large bornholm basin the two approaches termed the fgd free gas depth model and the hml holocene mud layer model yielded similar budgets for the total upwards methane flux through the sediment column in the bornholm basin about 17 ton methane c day 1 complete sulfate depletion at depth and thus onset of methane production required a minimum threshold thickness of the holocene mud layer of 4 m although the bornholm basin has an even depth contour and uniform surface sediments methane production was strongly focused in hotspots where the hml has greatest thickness this heterogeneity could not be predicted from bathymetry or from properties of the surface sediment but was related to the topography of the glacial landscape buried underneath the holocene mud blanket this demonstrates the importance of including seismo acoustic mapping of subsurface stratigraphy for the interpretation and geographic extrapolation of sediment core data for biogeochemical processes such as methane production and methane flux the two approaches which were here combined for the first time may thereby be applied to map methane production also in other coastal and shelf sediments with shallow gas and distinct holocene deposits

geochemical controls on arsenic and rare earth elements approximately along a groundwater flow path in the shallow aquifer of the hetao basin inner mongolia article i nfo groundwaters and sediments were sampled approximately along a groundwater flow path in the shallow aquifer of the hetao basin inner mongolia along a flow path with a length of about 9 km groundwater evolves from ca hco3 so4 through mg ca hco3 cl to na cl hco3 from the recharge zone to the discharge

dissolution reprecipitation process of magnetite from the chengchao iron deposit insights into ore genesis and implication for in situ chemical analysis of magnetite abstract magnetite formed in different environments commonly has distinct assemblages and concentrations of trace elements that can potentially be used as a genetic indicator of this mineral and associated ore deposits in this paper we present textural and compositional data of magnetite from the chengchao iron deposit daye district china to provide a better understanding in the formation mechanism and genesis of the deposit and shed light on analytical protocols for in situ chemical analysis of hydrothermal magnetite magnetite grains from the ore related granitoid pluton mineralized endoskarn magnetite dominated exoskarn and vein type iron ores hosted in marine carbonate intruded by the pluton were examined using scanning electron microscopy and analyzed for major and trace elements using electron microprobe back scattered electron images reveal that primary magnetite from the mineralized skarns and vein type ores were all partly reequilibrated with late stage hydrothermal fluids forming secondary magnetite domains that are featured by abundant porosity and have sharp contact with the primary magnetite these textures are interpreted as resulting from a dissolution reprecipitation process of magnetite which however are mostly obscure under optically primary magnetite grains from the mineralized endoskarn and vein type ores contain high sio 2 0 92 3 21 wt al 2 o 3 0 51 2 83 wt and low mgo 0 15 0 67 wt whereas varieties from the exoskarn ores have high mgo 2 76 3 07 wt and low sio 2 0 03 0 23 wt and al 2 o 3 0 54 1 05 wt this compositional contrast indicates that trace element geochemical composition of magnetite is largely controlled by the compositions of magmatic fluids and host rocks of the ores that have reacted with the fluids compared to its precursor mineral secondary magnetite is significantly depleted in most trace elements with sio 2 deceasing from 1 87 to 0 47 wt on average and al 2 o 3 from 0 89 to 0 08 wt in mineralized endoskarn and vein type ores and mgo from 2 87 to 0 60 wt in exoskarn ores on the contrary average content of iron is notably increased from 69 2 wt to 71 9 wt in the secondary magnetite grains the results suggest that the dissolution reprecipitation process has been important in significantly removing trace elements from early stage magnetite to form high grade high quality iron ores in hydrothermal environments the textural and compositional data confirm that the chengchao iron deposit is of hydrothermal origin rather than being crystallized from immiscible iron oxide melts as previously suggested this study also highlights the importance of textural characterization using various imaging techniques before in situ chemical analysis of magnetite as is the case for texturally complicated u th bearing accessory minerals that have been widely used for u pb geochronology study

geochemical and quality assessment of groundwater of marand basin east azarbaijan province northwestern iran the chemical analysis of 83 water wells in the marand area azarbaijan province nw of iran was evaluated to determine the hydrogeochemical processes and ion concentration background in the region over the entire area the dominated hydrochemical types are ca mg so4 cl ca so4 na cl and ca mg hco3 based on the total hardness the softness of the groundwater is determined according to electrical conductivity ec and sodium adsorption ratio sar the most dominant classes are c3 s1 c3 s2 c4 s2 and c2 s1 the major ion concentrations are below the acceptable level for drinking water the groundwater salinity hazard is medium to high but the na hazard is low to medium with regard to irrigation water the quality is low to medium so a drainage system is necessary to avoid the increase of toxic salt concentrations

rare earth elemental concentrations in some pacific northwest rivers abstract soluble rare earth element ree concentrations have been measured for five pacific northwest rivers columbia fraser klamath rogue and sacramento using radiochemical neutron activation analysis the relative abundances of the ree in river water resemble the ree abundance pattern in average sedimentary type rocks the la material balance in the oceans is discussed

spring water trace element geochemistry a tool for resource assessment and reconnaissance mineral exploration abstract geochemical data from 151 spring locations within the 37 000 km2 south nahanni river basin of the mackenzie mountains northwest territories were analysed as part of a reconnaissance assessment of mineral potential in this large and remote region statistical data analyses graphical methods and strategic grouping of springs according to geochemistry ph and temperature were used to identify regions with higher mineralization potential quickly and efficiently testing of internal consistency indicates that known world class deposits within the basin are readily detected but by different methods as different deposit types have different geochemical signatures a new 3 component approach was developed to analyze trace element data for signatures of mineralisation estimation of circulation depth and therefore maximum potential ore depth further refines the assessment of economic potential the depth of circulation of the spring waters ranged from 4 7 km to less than 200 m for the entire dataset in total 62 spring locations were identified as having anomalous trace metal content by one or more method approximately 40 of the dataset specifically 11 spring locations were classified as anomalous by all three methods and 17 by at least two methods and 34 by only one method

titanium mobility in metamorphic systems a review abstract titanium is a dispersed lithophile element commonly regarded as chemically immobile at sub magmatic temperatures however a growing number of field studies demonstrate that ti is somewhat mobile in certain environments this review examines the current state of knowledge concerning the mobility of ti during alteration and metamorphism of crustal rocks also considered are relevant ti oxide solubility data from experiments and determinations of ti concentrations in natural waters where ti mobility is well documented its length scale is 10 m however ti may move greater distances in deep crustal shear zones the solubility of ti oxides in geologic fluids is strongly temperature dependent under low to medium grade metamorphic conditions ti mobility is limited by the low solubility of ti oxides in the associated fluids under eclogite conditions ti mobility is probably limited not by ti oxide solubility which reaches 1 ti but by restricted fluid flow in low permeability rocks

formation of anhydrous and hydrous skarn in cu au ore deposits by magmatic fluids most skarn ore deposits are characterized by two distinctly different alteration styles an early prograde stage with anhydrous minerals such as garnet and pyroxene forms from relatively high temperature hypersaline liquid a later retrograde stage with hydrous minerals such as epidote amphibole and chlorite plus sulfide ore minerals forms from lower temperature lower salinity fluids these two alteration stages commonly have been thought to reflect a dominance of magmatic and meteoric water respectively with relevance to the source of ore metals we report data from two different skarn systems one being part of the world s largest cu au resource stable isotope compositions of anhydrous and hydrous alteration minerals from both deposits indicate a magmatic source for both the prograde and retrograde stages 18o averages 5 0 per mil for garnet range 3 4 7 2 6 5 per mil for pyroxene 4 3 8 2 and 7 1 per mil for amphibole 4 3 8 7 the d values of late amphibole are more complex with magmatic values 77 to 78 for one deposit and both magmatic and lighter values for another deposit that could be explained either by magmatic degassing or by limited mixing with meteoric water we conclude that the differences in fluid composition prograde versus retrograde stages resulted from a magmatic fluid that intersected its solvus during the early stage creating vapor and hypersaline liquid whereas in the later stage this magmatic fluid did not intersect its solvus because it followed a different cooling path this late low salinity liquid only boiled once its vapor pressure curve was reached causing sulfide ore to precipitate during the retrograde stage

geology geochemistry and geochronology of the dunde iron zinc ore deposit in western tianshan china abstract the dunde iron zinc deposit 185 mt at 35 fe located in the tianshan orogenic belt xinjiang northwest china is hosted in late carboniferous volcanic volcaniclastic rocks characterized by prograde skarn formation and retrograde alteration but the ore lacks any clear spatial link with intrusive rocks four stages of skarn formation and ore development can be recognized 1 a prograde skarn stage that formed grossularitic garnet gr 39 80 ad 15 58 and diposidic pyroxene di 63 97 2 a retrograde skarn stage dominated by the formation of magnetite with minor epidote ferropargasite apatite hematite and trace amounts of titanite and spinel 3 a sulfide stage dominated by the formation of arsenide loellingite and arsenopyrite and sulfide minerals sphalerite pyrrhotite pyrite chalcopyrite and minor galena calcite and traces of quartz and 4 a chlorite calcite stage mainly characterized by the formation of chlorite calcite and traces of sericite exsolution of droplet like and patchy chalcopyrite is developed within sphalerite of the sulfide stage indicating an exsolution temperature of 350 400 c as such the crystallization temperature of early stage magnetite may have been 400 c abundant fluid inclusions occur in calcite which include daughter mineral bearing h 2 o h 2 o and pure h 2 o inclusions the h 2 o inclusions have a wide range of homogenization temperatures from 147 c to 367 c with salinities of 2 4 23 4 wt nacl equivalent the daughter mineral bearing h 2 o inclusions have homogenization temperatures from 172 c to 347 c with salinities of 31 9 33 0 wt nacl equivalent using the chlorite geothermometer the temperature of chlorite formation is constrained to be between 152 c and 222 c average 194 c sulfur isotope compositions of pyrrhotite sphalerite pyrite and loellingite have a narrow range of 34 s values from 3 8 to 8 1 average 34 s 6 8 suggesting that the sulfur was magmatic derived zircon la icp ms u pb dating of wall rock dacite yields a weighted mean 206 pb 238 u age of 316 0 1 7 ma combined with previous dating results of magnetite mineralized diorite stocks diorite dikes and garnet skarn it can be inferred that the dunde iron zinc deposit formed in the late carboniferous after 316 ma and is genetically related to deep dioritic intrusions during the late carboniferous the tectonic setting of this region changed from subduction collision to extension accompanied by mantle derived magma underplating in deep after the formation of the iron zinc ore deposit the dunde district was intruded by an early permian k feldspar granite that yields a zircon la icp ms u pb age of 295 75 0 71 ma

inverse geochemical modeling of groundwater evolution with emphasis on arsenic in the mississippi river valley alluvial aquifer arkansas usa summary inverse geochemical modeling phreeqc was used to identify the evolution of groundwater with emphasis on arsenic as release under reducing conditions in the shallow 25 30 m mississippi river valley alluvial aquifer arkansas usa the modeling was based on flow paths defined by high precision 2 cm water level contour map x ray diffraction xrd scanning electron microscopic sem and chemical analysis of boring sediments for minerals and detailed chemical analysis of groundwater along the flow paths potential phases were constrained using general trends in chemical analyses data of groundwater and sediments and saturation indices data minteqa2 of minerals in groundwater modeling results show that calcite halite fluorite fe oxyhydroxide organic matter h 2 s gas were dissolving with mole transfers of 1 40e 03 2 13e 04 4 15e 06 1 25e 01 3 11 and 9 34 respectively along the dominant flow line along the same flow line fes siderite and vivianite were precipitating with mole transfers of 9 34 3 11 and 2 64e 07 respectively cation exchange reactions of ca 2 4 93e 04 mol for na 2 51e 04 mol on exchange sites occurred along the dominant flow line gypsum dissolution reactions were dominant over calcite dissolution in some of the flow lines due to the common ion effect the concentration of as in groundwater ranged from so 4 2 with co precipitation of as into sulfide is the limiting factor controlling dissolved as in groundwater

a review of the geological characteristics and mineralization history of iron deposits in the altay orogenic belt of the xinjiang northwest china abstract in this review we describe the geological characteristics and metallogenic tectonic origin of fe deposits in the altay orogenic belt within the xinjiang region of northwestern china the fe deposits are found mainly within three regions ordered from northwest to southeast the ashele kelan and maizi basins the principal host rocks for the fe deposits of the altay orogenic belt are the early devonian kangbutiebao formation the middle to late devonian altay formation with minor occurrences of lower carboniferous and early paleozoic metamorphosed volcano sedimentary rocks the principal mineral forming element groups of the deposits are fe fe cu fe mn fe p fe pb zn fe au and fe v ti the fe deposits are associated with distinct formations such as volcanic rocks skarn deposits pegmatites granite related hydrothermal vein mineralization and mafic pluton related v ti magnetite deposits the fe deposits are most commonly associated with volcanic rocks in the upper kangbutiebao formation in the volcano sedimentary kelan basin and in skarn deposits at several localities including the lower kangbutiebao formation in the volcano sedimentary maizi basin and the altay formation at jiaerbasidao kekebulake region homogenization temperatures of fluid inclusions in the prograde retrograde and sulfide stages of the skarn type deposit are mainly medium to high temperature cluster between 200 and 500 c medium temperature cluster between 200 and 340 c and low to medium temperature cluster between 160 and 300 c respectively ore fluids in the sedimentation period in the volcano sedimentary type deposit are characterized by low to medium temperature with a peak around 190 c low to moderate salinity 3 23 to 22 71 wt nacl equiv ore fluids in the pegmatite type deposit are characterized by low to medium temperature with a peak at 240 c low salinity with a peak around 9 wt nacl equiv an analysis of the isotopic data for fe deposits from the altay orogenic belt indicates that the sulfur was derived from several sources including volcanic rocks and granite as well as bacterial reduction of sulfate from seawater the present results indicate that different deposit types were derived from various sources the ree geochemistry of rocks and ores from the fe deposits in the altay orogenic belt suggests that the ore forming materials were derived from mafic volcanic rocks based on isotopic age data the timing of the mineralization can be divided into four broad intervals early devonian 410 384 ma middle devonian 377 ma early permian 287 274 ma and early triassic c 244 ma the ore forming processes of the fe deposits are closely related to volcanic activity and the emplacement of intermediate and felsic intrusions we conclude that fe deposits within the altay orogenic belt developed in a range of tectonic settings including continental arc post collisional extensional settings and intracontinental settings

transport of north pacific 137cs labeled waters to the south eastern atlantic ocean abstract during the reoccupation of the woce transect a10 at 30 s by the beagle2003 cruise the shots project partners collected a large number of samples for the analysis of isotopic tracers 137cs was mostly deposited on the oceans surface during the late 1950s and early 1960s after the atmospheric detonation of large nuclear devices which mostly occurred in the northern hemisphere the development of advanced radioanalytical and counting techniques allowed to obtain for the first time in this region a zonal section of 137cs water concentrations where little information existed before thus constituting an important benchmark for further studies 137cs concentrations in the upper waters 0 1000 m of the south eastern atlantic ocean are similar to those observed in the south western indian ocean suggesting transport of 137cs labeled waters by the agulhas current to the benguela current region in contrast bomb radiocarbon data do not show this feature indicating the usefulness of 137cs as a radiotracer of water mass transport from the indian to the south atlantic ocean

210pb and 137cs in margin sediments of the arctic ocean controls on boundary scavenging 1 210pb and 137cs were measured in 25 sediment cores collected during the international polar year from a transect spanning the north american arctic margin from the north bering sea to baffin bay davis strait profiles and inventories of the radioisotopes were used to determine sediment mixing and accumulation at each site and to assess the intensity of scavenging and burial sediment accumulation rates derived from 210pb and validated using 137cs are between 0 04 and 0 23 g cm 2 yr 1 210pb cannot be used to derive sedimentation rates for vigorously biomixed sediments from the north bering chukchi shelf elevated 137cs activities and inventories in recently deposited sediments imply delayed inputs of particle associated 137cs to the sediments likely transported from the watershed to the coast and subsequently redistributed to shelf slope sediments inventories of 210pbex in all cores meet or exceed the estimated supply of 210pbex from atmospheric deposition and decay of 226ra in the water column this implies that in contrast to the deep arctic ocean basin there is a sufficient supply of suspended particulates along the north american arctic margin to scavenge the supply of 210pbex 210pbex inventories in sediments are up to 21 fold greater than the in situ supply at some sites large inventories of 210pbex in sediments along the north bering chukchi shelf result primarily from focusing while those along the north chukchi slope barrow canyon and in baffin bay davis strait reflect strong boundary scavenging likely supported by lateral exchanges with deep interior atlantic origin waters

137cs water profiles in the south indian ocean an evidence for accumulation of pollutants in the subtropical gyre abstract the 137 cs seawater transect along the 20 s latitude in the indian ocean sampled during the round the globe beagle2003 blue ocean global expedition clearly shows a presence of two cores of higher 137 cs concentrations at 100 e and 55 e in water column depths between 100 and 200 m the subsurface maximum of 137 cs activity concentration 2 1 mbq l observed near 100 e is the highest level found in southern hemisphere seawater which is comparable to the maximum 137 cs concentration observed in north pacific surface water this transect represents the first high density sight of 137 cs distribution in south indian ocean waters the estimated 137 cs water column inventories up to 1240 bq m 2 normalized for the 1000 m water depth along the 20 s latitude are by a factor of three higher than would be expected from global fallout in the south indian ocean the estimated residence time of 137 cs in surface waters of the south indian ocean 30 years is by about a factor of two higher than for the north pacific the 137 cs data confirm a transport of surface waters from the north pacific via indonesian seas to the south indian ocean and to the subtropical gyre the subtropical gyre is an important reservoir of anthropogenic pollutants that have been transported from the north pacific and indian oceans to the south on a time scale of several decades

recent rates of sedimentation on irregularly flooded boreal baltic coastal wetlands responses to recent changes in sea level abstract boreal baltic coastal wetlands differ markedly from temperate salt marshes by their generally low maximum elevation between 0 and 1 m above m s l low seaward gradients and the irregular nature of flooding that is characteristic of the ne baltic sea coastal region as a result of these factors these wetlands have been considered to be threatened by future sea level rise this study presents results for two boreal baltic coastal wetland sites in estonia using the 210 pb and 137 cs radiometric dating methods to investigate the sedimentary development of these coastal systems recent coastal evolution has been largely driven by continuing glacio isostatic adjustment gia with maximum rates of 2 8 mm yr 1 around the nw estonian coast and the inherited geomorphological setting of generally flat lying coastal topography resulting in coastal emergence broad agreement exists between calculated rates of sedimentation identified within the core sequences average rates of sedimentation using the 210 pb excess cf cs or simple model range between 0 2 and 1 3 mm yr 1 these rates are corroborated using 137 cs which also suggests an increase in sedimentation rates during recent decades approaching maximum values for current land uplift additionally the 210 pb excess crs model reveals periods of sedimentation greatly in excess of these values in response to coastal flooding from known storm activity this study indicates that changes in sea level caused by variations in atmospheric pressure and storm surges can contribute a significant sedimentary component which coupled with gia processes has driven coastal wetland development emergence and the historical progradation of these wetland systems the recent acceleration in the rate of global sea level rise may subtly alter this relationship however current rates of gia and sedimentation will continue to maintain the progradation of boreal baltic coastal wetlands in the coming decades

transport and scavenging of pu in surface waters of the southern hemisphere oceans abstract the distribution of 239pu in atlantic and indian ocean waters about four decades after their main injection from atmospheric nuclear weapons tests is discussed recent data obtained in the framework of the shots southern hemisphere ocean tracer studies projects are evaluated and compared with previous investigations seawater samples were collected during the round the globe beagle2003 blue ocean global expedition along the 30 s transect in the atlantic and the 20 s transect in the indian ocean the results indicate transport of surface waters labelled with 239pu from the western north pacific via the indonesian seas to the south indian ocean and then to the south atlantic ocean along the whole beagle2003 sampling route the atlantic ocean has the lowest 239pu content due to its particle scavenging on the long way from the western north pacific on the other hand concentrations of the conservative 137cs tracer are in all three oceanic basins comparable the primary productivity reflected by the chlorophyll content in surface waters has similar longitudinal distribution as 239pu radioactive and chlorophyll tracers revealed that the most important current system in each southern oceanic basin is represented by the subtropical gyre while the main streams of the gyres maintain high concentrations of tracers inside the loops the tracer concentrations are the lowest

reconstruction of the 236u input function for the northeast atlantic ocean implications for 129i 236u and 236u 238u based tracer ages a reconstruction of historical discharges of 236u into the northeast atlantic ocean by nuclear installations is presented the nuclear reprocessing facilities sellafield sf great britain gb and la hague lh france and potentially also the nuclear fuel processing installation springfields sp gb represent the main contributors of 236u in the northeast atlantic ocean because data on 236u releases is lacking 236u discharges from sp and sf are estimated based on the u isotopic systematics found in the discharges from lh the resulting reconstruction of 236u releases indicates that until 2013 a total of 95 32 kg of 236u was discharged from sf sp and lh in a second step the reconstructed 236u releases are combined with 129i data from literature and oceanic and atmospheric box models are used to derive the 129i 236u and 236u 238u input functions that for example can be used to calculate tracer ages of atlantic waters in the arctic ocean our conceptual results show that the combination of 129i 236u and 236u 238u generally allows the estimation of tracer ages over the past approximately 25 yr if contributions of 236u from global fallout are considered finally as a proof of concept the new method is applied to calculate tracer ages of arctic ocean surface samples collected in 2011 12 and the results are in good agreement with literature data we conclude that the combination of 129i 236u with 236u 238u in a dual tracer approach provides a sensitive tool for the calculation of tracer ages and ventilation rates in the north atlantic region this article is protected by copyright all rights reserved

differentiation of nelsonitic magmas in the formation of the 1 74 ga damiao fe ti p ore deposit north china the 1 74 ga damiao anorthosite complex north china is composed of anorthosite and leuconorite with subordinate melanorite mangerite oxide apatite gabbronorite perthite noritic i e jotunitic and ferrodioritic dykes the complex hosts abundant vein pod and lens like fe ti p ores containing variable amounts of apatite 10 60 modal and fe ti oxides in addition to fe ti p ores there are also abundant fe ti ores which are closely associated with fe ti p ores in the deposit most of fe ti p ores are dominated by fe ti oxides and apatite devoid of silicate minerals mineralogically similar to the common nelsonites elsewhere in contrast fe ti ores are dominated by fe ti oxides with minor apatite 5 modal the parental magma of these ores estimated from olivine and apatite compositions using mineral melt partition coefficients has composition similar to the ferrodioritic dykes fe ti p ores have variable fe ti oxides and apatite proportions indicating that they are cumulates their simple assemblage of fe ti oxides and apatite and local net texture suggest that the fe ti p ores in damiao have formed from nelsonitic melts immiscibly separated from the ferrodioritic magma during late stage differentiation fe ti ores are also cumulates and have mineral compositions similar to fe ti p ores the close association between fe ti and fe ti p ores indicates that the fe ti ores may have also formed from the nelsonitic melts we proposed that differentiation of nelsonitic melts accompanied by gravity settling is responsible for the formation of fe ti and fe ti p ores such a differentiation process in nelsonitic melts is well supported by variations of sr y th u ree and eu eu of apatite in fe ti p ores using oxides apatite ratio of 2 1 and compositions of apatite and calculated primary oxides we estimate the composition of the nelsonitic melt as 52 0 wt fe2o3t 18 5 wt cao 14 2 wt p2o5 8 7 wt tio2 4 0 wt al2o3 and 1 1 wt mgo with minor sio2 k2o na2o and f such a nelsonitic melt is suggested to be possibly conjugated with si rich melts compositionally similar to the damiao jotunitic dykes 50 wt sio2 and 15 wt fe2o3t which may subsequently evolve to mangeritic rocks in damiao our modeling also indicates that the onset of immiscibility occurs at a time when the evolved melt has 44 wt sio2 21 wt fe2o3t 3 0 wt tio2 and 2 6 wt p2o5 high oxygen fugacity and phosphorous content in magmas may play important roles in the immiscibility of nelsonitic magmas including promoting iron enrichments and widening the two liquid field