a comparison of north american shale plays with emerging non marine shale plays in australia geological and petrophysical parameters are critical in evaluating the production potential of prospective shale gas plays and their economic viability for commercial development however based on the us experience these characteristics can vary widely furthermore the non marine shale plays of the cooper basin south australia are distinctively different from the marine shale plays in the us non marine shale may consist of higher clay content and thus may be less responsive to hydraulic fracturing due to the increased ductility conversely the availability of sufficient amounts of quartz and siderite may counteract this effect and maintain brittleness in this study the mineral total organic and gas content thermal maturity poisson s ratio and young s modulus data obtained from the roseneath and murteree formations of the cooper basin have been compared with us shale formations the results show that the formations compare well in terms of thickness thermal maturity young s modulus and poisson s ratio but not in clay mineral content and formation temperature and values for toc porosity and gas in place are comparatively lower to determine whether such plays are economically viable will require technical as well as economic analysis of the hydraulic fracturing process including the potential for horizontal and vertical well development or basin centred gas developments a shale play that has unfavourable prospects may have upfront infrastructure and major capital costs that outweigh the potential receipts from gas production

geochemical evidence for possible natural migration of marcellus formation brine to shallow aquifers in pennsylvania the debate surrounding the safety of shale gas development in the appalachian basin has generated increased awareness of drinking water quality in rural communities concerns include the potential for migration of stray gas metal rich formation brines and hydraulic fracturing and or flowback fluids to drinking water aquifers a critical question common to these environmental risks is the hydraulic connectivity between the shale gas formations and the overlying shallow drinking water aquifers we present geochemical evidence from northeastern pennsylvania showing that pathways unrelated to recent drilling activities exist in some locations between deep underlying formations and shallow drinking water aquifers integration of chemical data br cl na ba sr and li and isotopic ratios 87sr 86sr 2h h 18o 16o and 228ra 226ra from this and previous studies in 426 shallow groundwater samples and 83 northern appalachian brine samples suggest that mixing relationships between shallow ground water and a deep formation brine causes groundwater salinization in some locations the strong geochemical fingerprint in the salinized cl 20 mg l groundwater sampled from the alluvium catskill and lock haven aquifers suggests possible migration of marcellus brine through naturally occurring pathways the occurrences of saline water do not correlate with the location of shale gas wells and are consistent with reported data before rapid shale gas development in the region however the presence of these fluids suggests conductive pathways and specific geostructural and or hydrodynamic regimes in northeastern pennsylvania that are at increased risk for contamination of shallow drinking water resources particularly by fugitive gases because of natural hydraulic connections to deeper formations

preservation and detection of microstructural and taxonomic correlations in the carbon isotopic compositions of individual precambrian microfossils abstract here we present techniques for and new data from in situ carbon isotope 13c analysis of precambrian permineralized microscopic fossils with a reproducibility of 1 2 using secondary ion mass spectrometry sims individual microfossils selected for their excellent preservation were analyzed in petrographic thin sections of stromatolitic cherts from the proterozoic gunflint 1880 ma bitter springs 830 ma min yar 740 ma and chichkan 775 ma formations the range of 13c values 34 6 to 22 1 vpdb among the 46 individuals analyzed falls within that expected for photoautotrophic carbon fixation by ribulose bisphosphate carboxylase rubisco consistent with morphology based taxonomic assignments for these specimens microfossils classified as cyanobacteria from the gunflint bitter springs and min yar formations for which published carbonate carbon isotope data can be used to estimate the 13c of the original dissolved inorganic carbon substrate exhibit a consistent 19 total fractionation 13c of dissolved inorganic carbon 13c of biomass similar to that observed in living cyanobacteria over a wide range of 13ccarb values 2 9 to 3 4 in stromatolitic chert of the min yar formation morphologically diverse microfossils preserved in a 1 mm2 part of a microbial mat exhibit systematic isotopic differences among and within taxa that correlate with their morphologically inferred biological affinities and suggest that isotopic signatures of their original biosynthetic processes e g lipid and peptidoglycan synthesis are preserved isotopic offsets consistent with the different rubisco based fractionations typical of cyanobacteria and photosynthetic eukaryotes are documented by the differing 13c values of a colonial cyanobacterium 22 6 0 5 and a phytoplanktonic protistan acritarch 28 9 1 0 situated

geochemical evolution of produced waters from hydraulic fracturing of the marcellus shale northern appalachian basin a multivariate compositional data analysis approach abstract multivariate compositional data analysis methods were used to investigate geochemical data for water injected during hydraulic fracturing and for water produced from 19 marcellus shale gas wells in the northern appalachian basin the data were originally published as part of an industry report the analysis was adapted to consider the compositional nature of the data and avoid potentially spurious correlations present in raw concentration data through the application of log ratio transformations techniques such as robust variation arrays robust principal component analysis and relative variation plots were applied to log ratio transformed data results from this battery of multivariate tools indicate that two primary processes affect the chemical evolution of the water returned to the surface during the first 90 days of production mixing of injected water with formation brines of evaporated paleoseawater origin and injection of sulfate rich water during hydraulic fracturing may stimulate sulfate reduction at some sites spatial variability in sulfate alkalinity ratios appears to influence variations in geochemical controls on strontium versus barium with elevated proportions of strontium being found in more bicarbonate poor environments while barium is a larger proportion in sulfate poor areas comparison of results using a log ratio approach versus the more common analysis of concentration data reveals both similarities and some marked differences in the resulting interpretations results from this work are important in terms of both demonstrating methods to avoid mathematical inconsistencies from using raw brine geochemical data and to further investigate the geochemical controls on produced waters generated from shale gas reservoirs

paleoenvironmental and taphonomic controls on the occurrence of paleoproterozoic microbial communities in the 1 88ga ferriman group labrador trough canada abstract chert and iron formation from the ferriman group ca 1 88 ga labrador trough canada contain an exceptional assemblage of fossil bacteria and biofilms preserved within a well defined stratigraphic framework lithofacies associations suggest that microbes were restricted to suboxic shallow water environments through three sea level cycles microfossils are preserved as chert or sedimentary apatite francolite in hematite rich peritidal facies nearshore evaporation and fe redox pumping of silica drove rapid penecontemporaneous silicification of microbial mats in some communities breakdown of organic matter and fe redox pumping of pore water phosphate caused their syndepositional phosphatization preservation of bacteria was precluded in deeper settings because these processes could not operate at an anoxic seafloor filamentous forms dominate microbial morphologies secondary electron imaging of freshly broken surfaces shows filaments that are similar in size and shape to modern bacteria filaments vary from 0 5 and 1 m wide and reach tens of m in length they commonly envelop chert and iron oxide grains which stabilized the seafloor and contributed to firmground development the filamentous morphology similar mat forming behavior and suboxic paleoenvironments where these fossils lived are consistent to those of modern fe oxidizing bacteria and some cyanobacteria associated organic matter with low 13 c values is also present most values vary between ca 38 and 20 which is consistent with isotopic fractionation by such bacteria unlike modern settings however their distribution was restricted to shallow marine and peritidal environments where photosynthetically produced oxygen oases likely impinged on the seafloor although fe oxidizing bacteria were possibly important in forming some iron formation facies in the ferriman group physiochemical precipitation of fe oxyhydr oxides caused by photosynthetic oxygen was also probably widespread in the photic zone across the shelf this study demonstrates that a combined microanalytical sedimentologic and stratigraphic analysis of fossil bacteria not only yields a more detailed picture of the precambrian biosphere but also highlights the importance of taphonomy in the search for early life

origin migration and mixing of brines in the permian basin geochemical evidence from the eastern central basin platform texas formation waters from producing reservoirs in paleozoic carbonates have been studied to determine the origin of brines on the eastern central basin platform in west texas chemical and isotopic analyses of these waters indicate mixing of brines of quite different origins in the deep subsurface of the permian basin formation waters from the middle permian san andres formation at 1430 m 4700 ft and from devonian limestones at 3200 m 10 500 ft have salinities of 26 59 g l and dd d18o values in the same range as modern precipitation and groundwater in the near surface ogallala aquifer na cl br concentrations and molar ratios show that the salinity of these waters was largely acquired through halite dissolution formation waters from pennsylvanian and lower permian shelf limestones at 2600 3000 m 8500 9800 ft are more saline 70 215 g l and apparently represent a mixture of two different fluids one end member was highly saline derived from seawater evaporated well beyond halite saturation and the other end member was a moderately saline meteoric water similar to the san andres and devonian formation waters halite beds occur only in upper permian upper guadalupian and ochoan strata in this area hence extremely saline evaporated seawater apparently descended into the paleozoic carbonates during halite deposition in the late permian mixing with and displacing marine formation waters by buoyancy driven convective flow these modified evaporitic brines were the dominant fluids in the paleozoic carbonates until the late tertiary when meteoric water began to flow into deeper paleozoic strata from outcrops and near surface aquifers in southeastern new mexico in association with tectonic uplift that began at 5 10 ma the meteoric water dissolved halite and anhydrite from permian evaporites near the basin margin and moved eastward along the regional hydraulic gradient mixing with and displacing the modified evaporitic brine in deeper hydrogeologic systems these late cenozoic meteoric fluids probably are responsible for widespread biodegradation of oil in the san andres grayburg interval the results of this study indicate that meteoric waters can migrate large distances and displace saline waters deep in a basin that has numerous oil reservoirs that have solution gas drive understanding the history of formation waters can assist in exploration and production through improved 1 interpretation of reservoir rock diagenesis 2 prediction of oil biodegradation and displacement 3 understanding of subsurface water pressures and 4 interpretation of hydrocarbon saturations from resistivity logs

the effect of early diagenesis on the fe isotope compositions of porewaters and authigenic minerals in continental margin sediments abstract iron isotope compositions in marine pore fluids and sedimentary solid phases were measured at two sites along the california continental margin where isotope compositions range from 56fe 3 0 to 0 4 at one site near monterey canyon off central california organic matter oxidation likely proceeds through a number of diagenetic pathways that include significant dissimilatory iron reduction dir and bacterial sulfate reduction whereas at our other site in the santa barbara basin dir appears to be comparatively small and production of sulfides fes and pyrite was extensive the largest range in fe isotope compositions is observed for fe ii aq in porewaters which generally have the lowest 56fe values minimum 3 0 near the sediment surface and increase with burial depth 56fe values for fes inferred from hcl extractions vary between 0 4 and 0 4 but pyrite is similar at both stations where an average 56fe value of 0 8 0 2 was measured we interpret variations in dissolved fe isotope compositions to be best explained by open system behavior that involves extensive recycling of feflux this study is the first to examine fe isotope variations in modern marine sediments and the results show that fe isotopes in the various reactive fe pools undergo isotopic fractionation during early diagenesis importantly processes dominated by sulfide formation produce high 56fe values for porewaters whereas the opposite occurs when fe iii oxides are present and dir is a major pathway of organic carbon respiration because shelf pore fluids may carry a negative 56fe signature it is possible that the fe isotope composition of ocean water reflects a significant contribution of shelf derived iron to the open ocean such a signature would be an important means for tracing iron sources to the ocean and water mass circulation

the strontium isotopic evolution of marcellus formation produced waters southwestern pennsylvania abstract the production of natural gas and natural gas liquids from unconventional tight shale formations involves hydraulic fracturing and subsequent removal of fluids co produced with the gas the chemistry of the returning fluid reflects the original composition of the injection water mobilized constituents in the shale formation and co mingled formation waters liberated by hydraulic fracturing produced water from unconventional gas wells tapping the middle devonian marcellus formation is characterized by high total dissolved solids tds including very high strontium concentrations in this study the strontium isotope composition 87 sr 86 sr was measured in produced waters from four horizontally drilled hydraulically fractured marcellus shale gas wells in southwestern pennsylvania sampled from the first day after commencement of flowback to as much as 27 months later the 87 sr 86 sr of the waters tended to change rapidly over the first few days of water return and then approached but did not reach a constant range of values from 0 7113 to 0 7114 which appears to be characteristic of this part of the marcellus play in contrast the concentration of sr rose more slowly and appeared to hit a steady state value up to 3000 mg l by the end of the first year taken together with results from earlier work these data suggest mixing between injected frac fluid and high tds formation water highly enriched in sr and isotopically relatively uniform throughout the marcellus shale gas play this brine could exist within porous lenses of organic matter in the shale in pre existing fractures within the shale and or originate from fluids that migrated from adjacent formations at some point during the post depositional history of the basin

geochemical interactions of shale and brine in autoclave experiments understanding mineral reactions during hydraulic fracturing of marcellus and eagle ford shales geochemical interactions between shale and hydraulic fracturing fluid may affect produced water chemistry and rock properties it is important to investigate the rock water reactions to understand the impacts eight autoclave experiments reacting marcellus and eagle ford shale samples with synthetic brines and a friction reducer were conducted for more than 21 days to better determine mineral dissolution and precipitation at the rock water interface the shale samples were ion milled to create extremely smooth surfaces that were characterized before and after the autoclave experiments using scanning electron microscopy sem this method provides an unprecedented level of detail and the ability to directly compare the same mineral particles before and after the reaction experiments dissolution area was quantified by tracing and measuring the geometry of newly formed pores changes in porosity and permeability were also measured by mercury intrusion capillary pressure micp tests aqueous chemistry and sem observations show that dissolution of calcite dolomite and feldspar and pyrite oxidation are the primary mineral reactions that control the concentrations of ca mg sr mn k si and so4 in aqueous solutions porosity measured by micp also increased up to 95 which would exert significant influence on fluid flow in the matrix along the fractures mineral dissolution was enhanced and precipitation was reduced in solutions with higher salinity the addition of polyacrylamide a friction reducer to the reaction solutions had small and mixed effects on mineral reactions probably by plugging small pores and restricting mineral precipitation the results suggest that rock water interactions during hydraulic fracturing likely improve porosity and permeability in the matrix along the fractures by mineral dissolution the extent of the geochemical reactions is controlled by the salinity of the fluids with higher salinity enhancing mineral dissolution

selenium enrichment in carboniferous shales britain and ireland problem or opportunity for shale gas extraction research was partly supported by nerc grants ne l001764 1 and ne m010953 1 mrs a sandison provided skilled technical support barnett shale was kindly provided by hu qinhong the manuscript was improved by the helpful comments of a reviewer

geochemical evaluation of flowback brine from marcellus gas wells in pennsylvania usa large quantities of highly saline brine flow from gas wells in the marcellus formation after hydraulic stimulation fracking this study assesses the composition of these flowback waters from the marcellus shale in pennsylvania usa concentrations of most inorganic components of flowback water cl br na k ca mg sr ba ra fe mn total dissolved solids and others increase with time from a well after hydraulic stimulation based on results in several datasets reported here the greatest concentration of cl in flowback water is 151 000 mg l for total ra combined 226ra and 228ra in flowback the highest level reported is 6540 pci l flowback waters from hydraulic fracturing of marcellus wells resemble brines produced from conventional gas wells that tap into other paleozoic formations in the region the br cl ratio and other parameters indicate that both types of brine formed by the evaporation of seawater followed by dolomitization sulfate reduction and subsurface mixing with seawater and or freshwater trends and relationships in brine composition indicate that 1 increased salt concentration in flowback is not mainly caused by dissolution of salt or other minerals in rock units 2 the flowback waters represent a mixture of injection waters with highly concentrated in situ brines similar to those in the other formations and 3 these waters contain concentrations of ra and ba that are commonly hundreds of times the us drinking water standards

quantitative mineralogy for facies definition in the marcellus shale appalachian basin usa using xrd xrf integration abstract determining the mineralogy of mature sedimentary rocks particularly mudrock often defaults to qualitative or semi quantitative methods due to difficulties in correctly quantifying multiple unknown mineral phases constraining mineral abundances is particularly difficult in shale due to preferred mounting orientation of common phyllosilicate phases commonly leading to overestimation of clay minerals and mica we introduce a quantitative approach to constraining mineralogy within mudrock by integrating x ray diffraction xrd and x ray fluorescence xrf data sets collected on splits of the same samples the technique involves partitioning xrf cation concentrations into xrd identified silicate carbonate and sulfide phases then estimating quartz by xrf sio2 balance this method is applied to an example dataset from the economically significant marcellus shale middle devonian appalachian basin usa conventional reference intensity ratio rir interpretation identified nine mineral phases quartz muscovite illite pyrite chlorite albite calcite dolomite and barite their abundances were then re estimated using more highly accurate xrf derived elemental concentrations with stoichiometry from the identified xrd reference phases xrf al2o3 was used to corroborate the calculated xrd xrf results for quality control errors in relevant xrf concentrations can be quantified though not the assumptions in how they are employed nonetheless the resulting xrd xrf mineralogic abundances by this procedure are thought to be more accurate than rir and to remove preferred orientation bias induced that causes overestimation of clay minerals and mica and underestimation of quartz and other phases cluster analysis of the xrd xrf results identified four mineralogical facies that provide insight into potential primary depositional controls on organic matter preservation within the marcellus shale this xrd xrf integration method provides a general framework for estimating mineralogy quantitatively in mudrocks although dataset specific adjustments to the method may be required for different mineralogical suites

biosignatures link microorganisms to iron mineralization in a paleoaquifer concretions preferentially cemented masses within sediments and sedimentary rocks are records of sediment diagenesis and tracers of pore water chemistry for over a century rinded spheroidal structures that exhibit an fe iii oxide rich exterior and fe poor core have been described as oxidation products of fe ii carbonate concretions however mechanisms governing fe iii oxide precipitation within these structures remain an enigma here we present chemical and morphological evidence of microbial biosignatures in association with fe iii oxides in the fe iii oxide rich rind of spheroidal concretions collected from the jurassic navajo sandstone southwest united states implicating a microbial role in fe biomineralization the amount of total organic carbon in the exterior fe iii oxides exceeded measured values in the friable interior the mean 13 c value of organic carbon from the fe iii oxide cemented exterior 13 c of 20 55 is consistent with a biogenic signature from autotrophic bacteria scanning electron micrographs reveal microstructures consistent with bacterial size and morphology including a twisted stalk morphotype that resembled an fe ii oxidizing microorganism gallionella sp nanoscale associations of fe o c and n with bacterial morphotypes demonstrate microorganisms associated with fe iii oxides together these results indicate that autotrophic microorganisms were present during fe iii oxide precipitation and present microbial catalysis as a mechanism of fe iii oxide concretion formation microbial biosignatures in rinded fe iii oxide rich concretions within an exhumed quaternary aquifer has broad implications for detection of life within the geological record on earth as well as other fe rich rocky planets such as mars where both fe ii carbonate and fe iii oxide rich concretions have been identified

geochemical and isotopic variations in shallow groundwater in areas of the fayetteville shale development north central arkansas exploration of unconventional natural gas reservoirs such as impermeable shale basins through the use of horizontal drilling and hydraulic fracturing has changed the energy landscape in the usa providing a vast new energy source the accelerated production of natural gas has triggered a debate concerning the safety and possible environmental impacts of these operations this study investigates one of the critical aspects of the environmental effects the possible degradation of water quality in shallow aquifers overlying producing shale formations the geochemistry of domestic groundwater wells was investigated in aquifers overlying the fayetteville shale in north central arkansas where approximately 4000 wells have been drilled since 2004 to extract unconventional natural gas monitoring was performed on 127 drinking water wells and the geochemistry of major ions trace metals ch4 gas content and its c isotopes d

carbon isotope fractionation by circumneutral iron oxidizing bacteria bacteriogenic iron oxides in natural environments are characterized by an abundance of ferrihydrite precipitates intermixed with bacterial structures that commonly resemble those produced by the lithoautotrophic microorganisms gallionella ferruginea and leptohtrix ochracea these species have been inferred to play a causal role in the formation of bacteriogenic iron oxides providing a pathway for the reduction of co 2 and the depletion of 13 c in the organic constituents of bacteriogenic iron oxides in this study stable carbon isotope fractionation was determined for bacteriogenic iron oxide samples collected from submarine hydrothermal vents axial volcano juan de fuca ridge subterranean aspo hard rock laboratory sweden and surficial chalk river canada groundwater seeps and cultures of g ferruginea data were also collected from ferrihydrite samples lacking evidence of bacteria from bounty seamount in the vicinity of pitcairn island the mean 13 c of ferrihydrite was determined to be 15 87 4 96 for the samples from axial volcano 24 97 0 43 for aspo 27 80 0 85 for chalk river 29 3 0 2 for the microbial culture and 8 43 1 89 for the samples from pitcairn samples with the highest concentration of organic carbon also had the lightest 13 c in a logarithmic relationship the consistency of carbon isotope values in relation to the presence of iron oxidizing bacteria from natural and laboratory samples is interpreted as the ability of these microorganisms to fractionate carbon the potential of this fractionation to serve as a biosignature holds promise when the resistance of carbon and bacteriogenic ferrihydrite to diagenesis is taken into consideration

geochemistry of metal rich brines from central mississippi salt dome basin u s a abstract oil field brines are the most favored ore forming solutions for the sediment hosted mississippi valley type ore deposits detailed inorganic and organic chemical and isotope analyses of water and gas samples from six oil fields in central mississippi one of the very few areas with high metal brines were conducted to study the inorganic and organic complexes responsible for the high concentrations of these metals the samples were obtained from production zones consisting of sandstone and limestone that range in depth from 1900 to 4000 m 70 120 c and in age from late cretaceous to late jurassic results show that the waters are dominantly bittern brines related to the louann salt the brines have extremely high salinities that range from 160 000 to 320 000 mg l total dissolved solids and are na ca cl type waters with very high concentrations of ca up to 48 000 mg l and other alkaline earth metals but with low concentrations of aliphatic acid anions the concentrations of metals in many water samples are very high reaching values of 70 mg l for pb 245 mg l for zn 465 mg l for fe and 210 mg l for mn the samples with high metal contents have extremely low concentrations 2 s samples obtained from the smackover formation limestone have low metal contents that are more typical of oil field waters but have very high concentrations up to 85 mg l of h 2 s computations with the geochemical code solmineq 87 give the following results 1 both pb and zn are present predominantly as aqueous chloride complexes mainly as pbcl 4 2 and zncl 4 2 respectively 2 the concentrations of metals complexed with short chained aliphatic acid anions and reduced s species are minor 3 organic acid anions are important in controlling the concentrations of metals because they affect the ph and buffer capacity of the waters at subsurface conditions and 4 galena and sphalerite solubilities control the concentrations of pb and zn in these waters

iron mineralization and taphonomy of microfossils of the 2 45 2 21 ga turee creek group western australia abstract we report a new assemblage of carbonaceous microfossils intimately associated with siderite and fe silicates from a black chert nodule included in iron formation of the ca 2 45 2 21 ga turee creek group western australia this chert comprises microbial fabrics dominated by filaments preserved in matrix of nano to micrometric quartz filaments occur in clumps and in a cobweb like fabric interspersed with coarse crystalline void filling quartz granules we studied this chert with optical microscopy combined with scanning transmission electron microscope observations of focused ion beam sections of microfossils this distinguished three types of well preserved fossil interpreted as polysaccharide sheaths that usually do not preserve chains of cells trichomes type 1 comprises narrow filaments with thin continuous kerogen sheaths type 2 comprises narrow filaments with thick granular sheaths and type 3 comprises broad filaments with thin sheaths type 4 filaments are poorly preserved as granular kerogen organic ultrastructures of type 2 4 microfossils are variably replaced by siderite crystals associated with minor fe silicates iron isotope analyses on bulk powder and reactive iron fraction show indistinguishable and highly positive 56 fe values 1 45 relative to the reference irmm 014 indicating that the bulk of siderite derives from reduction of fe iii oxides this provides indirect evidence that the microbial community was originally associated with fe iii oxides siderite and fe silicates are found with type 2 4 but not type 1 filaments suggesting that only the former were encrusted by fe iii oxides which may have been reduced in situ siderite and fe silicates could result from oxidation of organic matter in filaments coupled with microbial and or thermal reduction of fe iii bio minerals the increasing abundance of siderite correlated with decreasing organic matter preservation in filaments supports that this reaction occurred to variable extents in situ on each microfossil type 2 4 microfossils may thus represent iron oxidizing bacteria these microbial mats display strong similarities with those associated with immediately overlying carbonate rocks of the turee creek group where filaments were interpreted as sulfur oxidizing bacteria some filamentous bacteria can oxidize both iron and sulfur such metabolic versatility could have enabled benthic microbial mats to thrive in the drastically changing chemical conditions of the great oxidation event

hydrogeochemical and isotopic evidence of groundwater salinization in a coastal aquifer a case study in jeju volcanic island korea abstract in order to identify the origin of saline groundwater in the eastern part of jeju volcanic island korea a hydrogeochemical and isotopic study has been carried out for 18 observation wells located in east and southeast coastal regions the total dissolved solid contents of groundwaters are highly variable 77 21 782 mg l oxygen hydrogen sulfur and strontium isotopic data clearly show that the saline water results from mixing of groundwater with seawater strontium isotopic compositions and br cl and i cl ratios strongly suggest that the source of salinity is modern seawater intrusion hydrogeochemical characteristics based on bivariate diagrams of major and minor ions show that changes in the chemical composition of groundwater are mainly controlled by the salinization process followed by cation exchange reactions the highly permeable aquifers at the east coastal region are characterized by low hydraulic gradient and discharge rate and high hydraulic conductivity as compared with other regions these properties enhance the salinization of groundwater observed in the study area based on the cl br and 18 o data seawater was determined to have intruded inland some 2 5 km from the coastline considering the poor correlation of sampling depth and cl concentrations observed the position of seawater freshwater interface is not uniformly distributed in the study area due to heterogeneities of the basaltic aquifers

origin of brines salts and carbonate from shales of the marcellus formation evidence from geochemical and sr isotope study of sequentially extracted fluids fluids co produced with methane from hydraulically fractured organic rich shales of the marcellus formation usa are characterized by high total dissolved solids tds including elevated levels of ba sr and br to investigate the source and geologic history of these high tds fluids and their dissolved constituents we carried out a series of sequential extraction experiments on dry drilled cuttings extracted within below and above the marcellus shale from a well in tioga county new york state the experiments were designed to extract 1 water soluble components 2 exchangeable cations 3 carbonate minerals and 4 hydrochloric acid soluble constituents the geochemistry of the resultant leachates highlights the different geochemical reservoirs for extractable elements within the shale notably na and br were largely water soluble while ba was extracted primarily from exchangeable sites and ca and sr were found both in exchangeable sites and carbonate strontium isotope ratios measured on the leachates indicate that each of the element reservoirs has a distinct value measured 87sr 86sr ratios in the water soluble component are similar to those of marcellus produced water while the ion exchange reservoir yields lower ratios and carbonate sr is lower still approaching devonian silurian seawater values despite the isotopic similarity of water leachates and produced water the total water chemistry argues against generation of produced water by interaction of hydraulic fracturing fluid with dry shale the high tds produced water is most likely trapped formation water within and or adjacent to the shale that is released by hydraulic fracturing the formation water was affected by multiple processes possibly including basin scale tectonically driven fluid flow significant chemical and isotopic differences between marcellus shale produced water and overlying upper devonian lower mississippian produced waters suggests a hydrologic barrier has been maintained in parts of the appalachian basin since the late paleozoic

rapid desorption of radium isotopes from black shale during hydraulic fracturing 2 a model reconciling radium extraction with marcellus wastewater production abstract radium in hydraulic fracturing wastewaters derives from two isotopically distinct end members in the shale labile 228ra hosted by mineral surfaces 226ra 228ra atom ratio 250 and exchangeable 226ra hosted by organic surfaces 226ra 228ra 10 000 here we use mass balance and isotope mixing models to reconcile extraction of ra from these phases with mechanisms of marcellus wastewater production radium isotopic mass balance requires that the characteristic water rock ratio between wastewater and shale is exceedingly low on the order of 0 04 and that this ratio decreases with time during wastewater production an evolving water rock interaction drives increasing ra concentrations ra and 226ra 228ra ratios during wastewater production all mediated by increasing ca2 that favors desorption of 226ra from organics our observations and models of ra isotope geochemistry are best reconciled with observations of water and salinity mass balance 18o na br cl and 87sr 86sr if wastewater is produced by mixing of injected fluids with a limited volume of pore brine on the order of 13 by volume accompanied by contemporaneous extraction of excess alkaline earth elements by water rock exchange validated using ra isotope data this model attributes the extreme salinity and ra in wastewaters to the progressive hydrologic enrichment of injected fluids during hydraulic fracturing

trace metal distribution and mobility in drill cuttings and produced waters from marcellus shale gas extraction uranium arsenic barium development of unconventional shale gas wells can generate significant quantities of drilling waste including trace metal rich black shale from the lateral portion of the drillhole we carried out sequential extractions on 15 samples of dry drilled cuttings and core material from the gas producing middle devonian marcellus shale and surrounding units to identify the host phases and evaluate the mobility of selected trace elements during cuttings disposal maximum whole rock concentrations of uranium u arsenic as and barium ba were 47 90 and 3333 mg kg 1 respectively sequential chemical extractions suggest that although silicate minerals are the primary host for u as much as 20 can be present in carbonate minerals up to 74 of the ba in shale was extracted from exchangeable sites in the shale while as is primarily associated with organic matter and sulfide minerals that could be mobilized by oxidation for comparison u and as concentrations were also measured in 43 produced water samples returned from marcellus shale gas wells low u concentrations in produced water 0 084 3 26 g l 1 are consistent with low oxygen conditions in the wellbore in which u would be in its reduced immobile form arsenic was below detection in all produced water samples which is also consistent with reducing conditions in the wellbore minimizing oxidation of as bearing sulfide minerals geochemical modeling to determine mobility under surface storage and disposal conditions indicates that oxidation and or dissolution of u bearing minerals in drill cuttings would likely be followed by immobilization of u in secondary minerals such as schoepite uranophane and soddyite or uraninite as conditions become more reducing oxidative dissolution of arsenic containing sulfides could release soluble as in arsenate form under oxic acidic conditions the degree to which the as is subsequently immobilized depends on the redox conditions along the landfill flow path the results suggest that proper management of drill cuttings can minimize mobilization of these metals by monitoring and controlling eh ph and dissolved constituents in landfill leachates

hydrothermal phase stabilization of 2 line ferrihydrite by bacteria poorly ordered 2 line ferrihydrite deposits from the caldera of axial volcano a site of hydrothermal vent activity along the juan de fuca ridge are characterized by an abundance of bacterial structures resembling gallionella ferruginea leptothrix ochracea and pv 1 filaments encrusted with nanoparticulate ferrihydrite ferrihydrite formed in the absence of bacteria can be metastable and will subsequently react to form more structurally ordered iron oxide phases such as hematite or goethite inspection of samples from 2 day 80 c aqueous heating experiments by electron microscopy and x ray diffraction revealed that a natural sample of bacteriogenic ferrihydrite from axial volcano did not undergo a phase transition whereas synthetic ferrihydrite absent of bacteria transformed to hematite after 2 days a series of bacterial ferrihydrite composites exhibited decreasing amounts of transformation to hematite with increased amounts of fe iii bound to bacteria complete inhibition was observed when 50 of the total fe was bound as ferric iron and 50 was present as ferrihydrite for the synthetic ferrihydrite samples containing bacteria the inhibition of ferrihydrite transformation is attributed to microbial surface functional groups i e carboxyl phosphoryl amine constraining the brownian motion of surface bound ferrihydrite nanoparticles thereby eliminating the aggregation and rotation of particles required for crystal growth the stabilization of ferrihydrite will prolong the longevity of a highly reactive mineral phase which may have implications for marine geochemistry and environmental remediation preservation of bacteria encrusted with transformation resistant ferrihydrite may enhance the potential usefulness of bacteriogenic ferrihydrite to harbour bacterial microfossils imparting these types of samples with potential use for paleontology and astrobiology

organic remains in late palaeoproterozoic granular iron formations and implications for the origin of granules toward the end of the palaeoproterozoic era over 109 billion tonnes of banded bif and granular gif iron formations were deposited on continental platforms granules in iron formations are typically sub spherical structures 0 2 to 10 mm in size whereas concretions are 10 mm both types of spheroids are preserved throughout the sedimentological record their formation has typically been interpreted to originate from reworked fe rich sediments in high energy wave agitated shallow marine environments new evidence from six different late palaeoproterozoic granular iron formations gif however suggests that some granules are the result of diagenetic reactions in addition to other features driven by microbial processes and mechanical movements characteristic coarse grain interiors and septarian type cracks inside granules akin to those features in decimetre to meter size concretions are interpreted as desiccation features from hydrated diagenetic environments where sulphate and or ferric iron were reduced while organic matter om was oxidised inside granules those granules derived from sulphate reduction preserve diagenetic pyrite rims whereas those formed via ferric iron reduction preserve diagenetic magnetite along their rims other diagenetic minerals including apatite mixed with om and various carbonate phases are commonly preserved within granules combined with systematically 13c depleted carbonate these diagenetic mineral assemblages point to the oxidative decay of om as a major process involved in the formation of granules spheroidal equidistant haematite laminations surround some granules and contain apatite associated with carbonate om and ferric ferrous silicates and oxides that further suggest these structures were not shaped by wave action along sediment water interfaces but rather by chemical wave fronts and biomineralisation our results demonstrate that the formation mechanisms of gif also involve microbial activity and chemically oscillating reactions as such granules have excellent potential to be considered as promising biosignatures for studying precambrian biogeochemistry as well as astrobiology

formation of fe silicates and fe oxides on bacterial surfaces in samples collected near hydrothermal vents on the southern explorer ridge in the northeast pacific ocean samples collected in low temperature 2 50 degrees c waters near hydrothermal vents of the southern explorer ridge in the northeast pacific ocean contained fine 500 nm fe and mn oxide and fe silicate particles coating bacterial surfaces partially to totally mineralized bacteria along with bacterial exopolymers were covered with a mixture of poorly ordered si rich fe oxides possibly ferrihydrite mn oxides and fe silicates possibly nontronite minerals occur as very fine 2 20 nm granular material fine 20 100 nm needles and sheets small 200 500 nm nodules and filaments i e mineralized exopolymers under saturation conditions we infer that bacterial surfaces provided nucleation sites for poorly ordered oxides and silicates the formation of fe and mn oxides was likely initiated by the direct binding of soluble fe and mn species to reactive sites like carboxyl phosphate and hydroxyl groups present within the bacterial cell wall and the exopolymers fe silicate formation involved a more complex binding mechanism whereas metal ions such as fe possibly bridged reactive sites within the cell walls to silicate anions to initiate silicate nucleation

evaluating a groundwater supply contamination incident attributed to marcellus shale gas development high volume hydraulic fracturing hvhf has revolutionized the oil and gas industry worldwide but has been accompanied by highly controversial incidents of reported water contamination for example groundwater contamination by stray natural gas and spillage of brine and other gas drilling related fluids is known to occur however contamination of shallow potable aquifers by hvhf at depth has never been fully documented we investigated a case where marcellus shale gas wells in pennsylvania caused inundation of natural gas and foam in initially potable groundwater used by several households with comprehensive 2d gas chromatography coupled to time of flight mass spectrometry gcxgc tofms an unresolved complex mixture of organic compounds was identified in the aquifer similar signatures were also observed in flowback from marcellus shale gas wells a compound identified in flowback 2 n butoxyethanol was also positively identified in one of the foaming drinking water wells at nanogram per liter concentrations the most likely explanation of the incident is that stray natural gas and drilling or hf compounds were driven 1 3 km along shallow to intermediate depth fractures to the aquifer used as a potable water source part of the problem may have been wastewaters from a pit leak reported at the nearest gas well pad the only nearby pad where wells were hydraulically fractured before the contamination incident if samples of drilling pit and hvhf fluids had been available gcxgc tofms might have fingerprinted the contamination source such evaluations would contribute significantly to better management practices as the shale gas industry expands worldwide

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

mineralogy and trace element geochemistry of gas shales in the united states environmental implications abstract this paper presents a compilation of published mineralogic and trace element data from nine gas shales in the united states formations analyzed include the antrim bakken barnett eagle ford haynesville marcellus new albany utica and woodford these mineralogic and trace element data can be used to assess the potential for environmental impacts during hydraulic fracturing impacts addressed in this study include 1 the potential for acid rock drainage generation during gas shale weathering 2 the distribution of trace elements in gas shales and comparison with regulatory guidelines and 3 the implications for environmental management of well cuttings the use of the mineralogic data to assess the fracability of the gas shales is also considered compilations of the mineralogy and geochemistry of gas shales can be a valuable resource for managing real and perceived environmental problems associated with their exploitation comprehensive environmental assessment to fully address these issues in addition to other potential environmental impacts will require collection and collation of additional data on the mineralogy and trace element geochemistry of gas and other hydrocarbon producing shales

geochemical and isotopic evolution of water produced from middle devonian marcellus shale gas wells appalachian basin pennsylvania the number of marcellus shale gas wells drilled in the appalachian basin has increased rapidly over the past decade leading to increased interest in the highly saline water produced with the natural gas which must be recycled treated or injected into deep disposal wells new geochemical and isotopic analyses of produced water for 3 time series and 13 grab samples from marcellus shale gas wells in southwest and north central pennsylvania pa are used to address the origin of the water and solutes produced over the long term 12 months the question of whether the produced water originated within the marcellus shale or whether it may have been drawn from adjacent reservoirs via fractures is addressed using measurements of and activity these parameters indicate that the water originated in the marcellus shale and can be more broadly used to trace water of marcellus shale origin during the first 1 2 weeks of production rapid increases in salinity and positive shifts in values were observed in the produced water followed by more gradual changes until a compositional plateau was reached within approximately 1 yr the values and relationships between na cl and br provide evidence that the water produced after compositional stabilization is natural formation water the salinity for which originated primarily from evaporatively concentrated paleoseawater the rapid transition from injected water to chemically and isotopically distinct water while of the injected water volume had been recovered supports the hypothesis that significant volumes of injected water were removed from circulation by imbibition

a field guide to finding fossils on mars the martian surface is cold dry exposed to biologically harmful radiation and apparently barren today nevertheless there is clear geological evidence for warmer wetter intervals in the past that could have supported life at or near the surface this evidence has motivated national aeronautics and space administration and european space agency to prioritize the search for any remains or traces of organisms from early mars in forthcoming missions informed by 1 stratigraphic mineralogical and geochemical data collected by previous and current missions 2 earth s fossil record and 3 experimental studies of organic decay and preservation we here consider whether how and where fossils and isotopic biosignatures could have been preserved in the depositional environments and mineralizing media thought to have been present in habitable settings on early mars we conclude that noachian hesperian fe bearing clay rich fluvio lacustrine siliciclastic deposits especially where enriched in silica currently represent the most promising and best understood astropaleontological targets siliceous sinters would also be an excellent target but their presence on mars awaits confirmation more work is needed to improve our understanding of fossil preservation in the context of other environments specific to mars particularly within evaporative salts and pore fracture filling subsurface minerals

diagnostics of western himalayan satluj river flow warm season mam jjas inflow into bhakra dam in india summary here we analyze the variability of mam march april may and jjas june july august september seasonal satluj river flow into the bhakra dam in india through pearson anomaly correlation and composite analyses with antecedent and concurrent seasonal climatic and atmospheric circulation patterns the mam seasonal inflow of bhakra dam is significantly correlated with winter djf fm precipitation and temperature of the satluj basin while the correlation with fm was more prominent for precipitation snow 0 72 rainfall 0 60 and temperature diurnal temperature range dtr 0 76 and maximum temperature t max 0 57 the jjas inflow was also positively correlated with djf fm as well as jjas precipitation of the satluj basin while the correlation with basin average fm was the largest 0 54 these suggested that both mam and jjas inflow anomalies are linked with djf fm climate over the western himalayas and adjoining north and central indian plains which were also found to be linked with the fluctuation of equatorial concurrent sea surface temperature anomalies over the western indian ocean max anomaly correlation was 0 70 and mean sea level pressure over western pole of the southern oscillation sea saw region max pearson anomaly correlation was 0 60 low high mam inflow was found to be associated with negative positive precipitation anomalies over the basin and north india in djf and fm while fm precipitation anomaly is more concentrated over the western himalayas in addition low high jjas inflow is also associated with negative positive precipitation anomalies over the basin and north india in djf and over the western himalaya in fm and jjas negative geopotential height anomaly at 500 h pa z500 over siberia and northwestern pacific in djf and positive z500 anomaly over the northwest india in fm were noticed in low mam inflow years whereas high inflow in mam was linked with a negative z500 anomaly between two positive z500 anomaly regions one over eastern siberia stretched up to northern pacific and second over the eastern europe in djf which gets stronger in fm we also found southwesterly northeasterly wind vectors at 850 h pa pressure level uv850 bringing more less moisture to the western himalayas in djf and fm in high low mam jjas flow years

identification and quantification of regional brine and road salt sources in watersheds along the new york pennsylvania border usa abstract the ecologically sensitive susquehanna river basin srb is an important recharge area and drinking water source for a large population in the northeastern united states seasonal road salt application the presence of regional brines at shallow depths and produced waters associated with active and legacy conventional upper devonian oil and gas wells could increase total dissolved solids tds in groundwater and streams this study focused on srb watersheds along the new york pennsylvania border in order to assess current water quality and to establish baseline geochemistry for ground and surface water in a region with potential for increased development of the marcellus shale and other unconventional shale gas units geochemical composition was determined for 300 stream samples collected from ten sites in four watersheds over variable seasonal flow conditions and for groundwater from over 500 drinking water wells in this region results indicate that many streams and groundwater wells in the study area have elevated tds levels that indicate pre existing contributions from saline sources dilution of these inputs with fresh water and the lack of low level trace element concentrations and isotopic composition in many water quality analyses highlight the need for alternate robust and sensitive chemical signatures comparison with cl br anion ratios and 87sr 86sr isotope ratios indicate that the ba sr mg ratio can be used to discriminate between road salt and regional brine in these cases and mixing models show that even small additions 0 1 0 01 of these contaminants can be detected with this cation ratio the ba sr mg ratio may be even more sensitive by an order of magnitude to incursions of marcellus shale produced water depending on the composition of marcellus produced waters in this region this study highlights the need for baseline sampling of freshwater reservoirs and the characterization of potential high tds sources at a local and regional scale

carbon isotope distribution in organic matter and siderite of a modern metalliferous hydrothermal sediment and possible implications for gold associated with banded iron formation abstract the carbon isotope distribution in organic matter and siderite has been determined in the metalliferous ferruginous sediments of santorini greece the sediments were precipitated by the microaerophilic chemolithotrophic bacterium galionella ferruginea from reduced hydrothermal solutions in siderites precipitated due to high co2 fugacity the 13 c 12 c isotope ratio pdb was 6 5 permil whereas the ratio was 26 8 permil in organic matter produced by the bacteria the common occurrence of isotopically light carbon 13c 10 permil pdb in carbonates of banded iron formations bif s was proposed some years ago to be the result of the dilution of carbon of marine carbonates by isotopically light carbon originally present in organic matter the explanation for this dilution would be that fe iii in newly precipitated oxide hydroxides served as an electron acceptor during oxidation of the organic carbon to carbonate the corresponding redistribution of some reduced carbon in the newly precipitated ferruginous sediment to carbonate minerals in the proportions found in some bif s has been modelled in the present study the isotopic shift to 13c 11 2 permil of the carbonate minerals of such a dilution by carbon of biological origin is close to the values observed in the geological record therefore organic matter appears to have been much more abundant during the early phases of bif development the association of gold and reduced organic carbon is well established in for instance the witwatersrand type conglomerates and some archaean bif s of hydrothermal origin this association may therefore make it worthwhile evaluating once again the role of organic activity in the deposition of bif s and their potential as a source of gold

microbially mediated barite dissolution in anoxic brines abstract fluids injected into shale formations during hydraulic fracturing of black shale return with extraordinarily high total dissolved solids tds and high concentrations of barium ba and radium ra barite baso 4 has been implicated as a possible source of ba as well as a problematic mineral scale that forms on internal well surfaces often in close association with radiobarite ba ra so 4 the dissolution of barite by abiotic processes is well quantified however the identification of microbial communities in flowback and produced water necessitates the need to understand barite dissolution in the presence of bacteria therefore we evaluated the rates and mechanisms of abiotic and microbially mediated barite dissolution under anoxic and hypersaline conditions in the laboratory barite dissolution experiments were conducted with bacterial enrichment cultures established from produced water from marcellus shale wells located in northcentral pennsylvania these cultures were dominated by anaerobic halophilic bacteria from the genus halanaerobium dissolved ba was determined by icp oes and barite surfaces were investigated by sem and afm our results reveal that 1 higher amounts of barium up to 5 are released from barite in the presence of halanaerobium cultures compared to brine controls after 30 days of reaction 2 etch pits that develop on the barite 001 surface in the presence of halanaerobium exhibit a morphology that is distinct from those that form during control experiments without bacteria 3 etch pits that develop in the presence of halanaerobium exhibit a morphology that is similar to the morphology of etch pits formed in the presence of strong organic chelators edta and dtpa and 4 experiments using dialysis membranes to separate barite from bacteria suggest that direct contact between the two is not required in order to promote dissolution these results suggest that halanaerobium increase the rate of barite dissolution in anoxic and high ionic strength solutions additionally the increase in rate occurs without direct microbe mineral contact suggesting that metabolites secreted by the bacteria may be responsible for promotion of dissolution the findings of this study have implications for understanding barium cycling in marine hypersaline environments release of barium and associated radium from waste solids generated from energy and mining industries as well as potential for developing new anti scaling chemicals

chemical constraints and origins of four groups of gulf coast reservoir fluids pitzer s method for computing activity coefficients has been applied to reported fluid compositions in four groups of gulf coast reservoirs the mississippi and arkansas smackover formation the texas edwards group the texas frio formation and the louisiana miocene sequence the activity quotients in fluids from carbonate reservoirs imply a reaction relation between calcite and disordered dolomite in which ordering increases at higher temperatures this relationship indicates that an increasing mg ca molality ratio with decreasing temperature does not necessarily imply dolomite dissolution by an updip moving fluid instead it may reflect an approach to equilibrium between calcite and metastable dolomite activity quotients in fluids from clastic reservoirs imply a rea tion relation between chlorite illite potassium feldspar and quartz at temperatures above 100 c 212 f present fluid compositions in the smackover and the edwards appear to be related to the updip movement of louann brines from the gulf coast basin accompanied by dolomitization in particular bromide plots for the edwards fluids indicate simple dilution of louann brines with interstitial fluids similar plots for fluids from the smackover show the complicating effects of illite formation sylvite dissolution and halite recrystallization albitization may have occurred during fluid movement through clastics prior to entering the smackover and edwards present fluid compositions in the frio and miocene are apparently not related to louann brines the compositional data reflect the effects of halite dissolution the subsequent albitization of plagioclase and potassium feldspar and the dissolution of carbonates during secondary porosity formation

the evaporation path of seawater and the coprecipitation of br and k with halite brines and salt were sampled at the morton bahamas solar salt production facility on great inagua island in the bahamas the brines were analyzed by ion chromatography to define more precisely than heretofore the evaporation path of seawater to the end of the halite facies at inagua calcium carbonate begins to precipitate at a brine concentration factor of 1 8 times that of seawater gypsum begins to precipitate at a brine concentration of 3 8 times seawater and halite at a concentration factor of 10 6 three of the most concentrated brines from inagua 40 times seawater were evaporated further in the laboratory magnesium sulfate first precipitated at brine concentrations about 70 times those of seawater and potassium bearing phases began to precipitate for these brines at concentrations greater than 90 times those of seawater the distribution of coefficients of br and k between brines and halite were determined by combining analytical data for the inagua brines with measurements of the br and k content of halites from inagua and of halite which had precipitated from inagua brines during storage the observed average value of dbr is 0 032 in good agreement with some of the previous measurements the measured values of dk are highly variable 0 001 to 0 021 dk for halite precipitated early in the halite facies is in the vicinity of 0 015

ferruginous and manganiferous haloes around massive sulphide deposits of the urals proximal brecciform ferruginous and manganiferous rocks related to vms deposits of the urals are subdivided into jasperites gossanites and umbers in addition to thin bedded jaspers and cherts the coherence of host rock composition and mn fe fertility of the sediments have been established fe poor pink hematitic and gray sulphidic chert are typical of the felsic class of vms deposits in contrast the contents of fe vary from high to moderate in ferruginous rocks enclosed in basaltic units associate with vms deposits fe and mn rich ferruginous rocks and umbers occur in association with limestones and calcareous sedimentary rocks in both types of volcanic sequences a common feature of jasperites and umbers is the abundance of replacement textures of hyaloclastites and carbonates by hematite and silica in addition replacement of clastic sulphides by hematite and magnetite is a characteristic genetic feature of gossanites all of these sedimentary rocks are accompanied by pseudomorphs of hematite and quartz formed after bacterial filaments the abundance of replacement textures are supportive of the halmyrolysis model in addition to hydrothermal sedimentary and sub seafloor hydrothermal replacement theories study of chemical zonation of altered hyaloclasts shows depletion of their rims not only in mobile na k mg but also in immobile al ti and ree whereas si and fe are concentrated in situ the halmyrolysis model presented here involving organic rich calcareous hyaloclastic sediments resolves the problem of subtraction of al ti ree and other elements which are commonly immobile under hydrothermal conditions the evolution of the halmyrolysis process from acidic reducing to alkaline oxidized conditions infers a possible range in transformation from fe ii mg smectites to fe silicates and fe si oxides as precursors of brecciform jasperite and thin bedded jasper the higher acidic initial stage of gossanite formation seems to be required for oxidation of organic matter and or pyrite the acidic condition facilitates the temporal preservation of immobile elements al ti ree in immature chlorite hematite gossanites another peculiarity of the gossanite forming processes is the likely sorption of p u and v by iron hydroxides displacing sulphides the general evolution of all ferruginous sediments results in complete fe 2 oxidation and silicification accompanied by subtraction of other elements the vertical diagenetic differentiation leads to concentration of mn carbonates silicates and oxyhydroxides into the tops of jasperite and gossanite layers mn oxyhydroxides scavenge positively charged hydrated cations like co and ni near vent bacterial communities may activate the processes of volcanic glass and sulphide degradation the proposed processes of halmyrolysis followed by silicification in situ may resolve the enigma of silica rich sediment formation in a silica undersaturated ocean the discrimination between gossanite and jasperite is useful for elaboration of new criteria for local exploration of vms and mn deposits halo dispersion of gossanites covering an area about two to three times that of the massive sulphide deposit is a good vector for ore body discovery proximal gossanites can be differentiated from jasperites by presence of relic sulphide clasts or elevated contents of chalcophile elements cu fe zn pb bi te as sb ba noble metals au ag and distinct ree patterns with la and eu positive anomalies the development of halmyrolysis and biomineralization models merit further elaboration and testing in on going research in order to add or revise theories of iron and manganese deposit formation 2012 elsevier b v

rapid desorption of radium isotopes from black shale during hydraulic fracturing 1 source phases that control the release of ra from marcellus shale abstract hydraulic fracturing of the marcellus shale produces wastewaters that are hypersaline and highly enriched in isotopes of radium radium is understood to derive from the marcellus shale itself but its source phases and their contributions to wastewater production have not been described using sequential extractions and experimental leachates we characterize two distinct end members that could contribute ra to wastewaters 1 a mineral phase which hosts labile 228 ra and has 226 ra 228 ra atom ratios 250 and 2 an organic phase which hosts exchangeable 226 ra and has 226 ra 228 ra 10 000 in leaching experiments we observed rapid extraction of ra from these phases with high ionic strength solutions leaching up to 14 of ra from the shale in just hours radium concentrations and 226 ra 228 ra ratios increase with ca 2 of the leaching solution and solutions approaching 1 m ca 2 produce 226 ra 228 ra ratios compatible with marcellus wastewaters in contrast pure water removes 226 ra 228 ra ratios incompatible with wastewaters experimental results and wastewater data together provide a coherent picture that the distinctive ra isotopic signature of marcellus wastewaters results from contemporaneous water rock interactions that promote desorption of 226 ra from organics during hydraulic fracturing

hydrothermal oxide and nontronite deposits on seamounts in the eastern pacific deposits of fe oxide mud nontronite and fe mn crusts were sampled from the summits of two seamounts in the eastern pacific where low temperature 0 15 c hydrothermal fluids are issuing the deposits consist of x ray amorphous fe oxyhydroxide and are rich in fe 43 wt contain minor si and p 4 and 3 5 respectively and have very low mn 0 01 and other trace element contents other deposits where no current hydrothermal activity was observed consist of mud and crusts composed of amorphous material and poorly crystalline hematite goethite and smectite these deposits have slightly higher mn up to 2 and other trace element contents the mineralogical and chemical differences between the active and inactive deposits and crusts are interpreted to be due to recrystallization and contamination with detrital biogenic hydrogenous and possibly hydrothermal sulfide material nontronite deposits capped by fe mn oxides were sampled from one of the seamounts these deposits have compositions similar to other seafloor nontronite deposits and formed at low temperatures 30 c during mixing of low temperature hydrothermal fluids with seawater the oxide deposits consist almost entirely of long delicate filaments remarkably similar in morphology to genera of fe oxidizing bacteria such bacteria were probably important in catalyzing the oxidation and precipitation of iron from hydrothermal fluids on the seamounts the occurrence of nearly identical filament rich oxide deposits on two widely separated seamounts suggests that this type of deposit may be common on seamounts but previously unrecognized

shales at all scales exploring coupled processes in mudrocks abstract fine grained sedimentary rocks namely mudrocks including their laminated fissile variety shales make up about two thirds of all sedimentary rocks in the earth s crust and a quarter of the continental land mass organic rich shales and mudstones are the source rocks and reservoirs for conventional and unconventional hydrocarbon resources mudrocks are relied upon as natural barriers for geological carbon storage and nuclear waste disposal consideration of mudrock multi scale physics and multi scale spatial and temporal behavior is vital to address emergent phenomena in shale formations perturbed by engineering activities unique physical characteristics of shales arise as a result of their layered and highly heterogeneous and anisotropic nature low permeability fabric compositional complexity and nano scale confined chemical environments barriers of lexicon among geoscientists and engineers impede the development and use of conceptual models for the coupled thermal hydraulic mechanical chemical biological thmcb processes in mudrock formations this manuscript reviews the thmcb process couplings resulting emergent behavior and key modeling approaches we identify future research priorities in particular fundamental knowledge gaps in understanding the phase behavior under nano scale confinement coupled chemo mechanical effects on fractures the interplay between physical and chemical processes and their rates and issues of non linearity and heterogeneity we develop recommendations for future research and integrating multi disciplinary conceptual models for the coupled multi scale multi physics behavior of mudrocks consistent conceptual models across disciplines are essential for predicting emergent processes in the subsurface such as self focusing of flow time dependent deformation creep fracture network development and wellbore stability