hydrochemical processes in the lower jordan valley and in the dead sea area abstract changes in the concentrations of major some minor and trace elements occurring in both surface and groundwater of the lower jordan river dead sea drainage basin have been investigated in order to identify the characteristics of the regional aquifers and their recharge areas spider patterns of elements and rare earth distribution patterns pinpoint the characteristic chemical features of groundwater as compared to seawater the high br cl ratios in groundwater are caused either by high br cl ratios in precipitation by leaching of br from bituminous matter or by mixing with brines beyond the epsomite stage the locations of groundwater samples with enhanced b contents coincide with the distribution of gypsum in the beds of the lisan formation which produces water with nearly constant b so 4 2 molar ratios aeolian distribution of the unconsolidated lisan sediments influences the b so 4 ratio in the area of lake tiberias and in the jordan highlands the high gd anomaly in the dead sea water is of geologic origin whereas that in the jordan river and in nahal stream qidron is largely anthropogenic the anthropogenic gd input to the dead sea is insignificant compared to the actual amount in the water of the dead sea hot saline water encountered along the western shores of the dead sea with high gd anomalies indicate that they contain large amounts of ancient dead sea water that mix as hot ascending brines with fresh water the recharge area of groundwater in the lower jordan valley extends largely over limestone and dolomite outcrops of the upper cretaceous judea group weathering of locally underlying lower cretaceous volcanics in the area of pezael beqaot and argaman yield groundwater with 34 s so 4 2 values ranging from 2 to 4 the presence of sulphide bearing bodies in this area is attested to magnetic anomalies detected at depths of several kilometres 34 s so 4 2 indicates very deep groundwater circulation high 34 s so 4 2 15 is typical for marine sulphates from the judea and avedat group limestone the springs located along the northwestern shore of the dead sea discharge water replenished on the eastern judea mountains the increase in the salinity of this water is due to brines flushed from sediments and from adjacent sedimentary rocks which host entrapped brines from the precursors of the dead sea formed during the late stages of lake lisan fresher water flushes out these residual brines as a result of falling sea level salinity increase in groundwater is also affected by the ascent of deep seated hot brines from pre sedom periods along the rift faults calculations of mixing between fresh and highly saline end members show that leaching of anhydrite from sediments precipitation of calcite formation of dolomite albitization of plagioclase and ion exchange with abundant clay minerals control the major element composition of the saline groundwater

geochemistry of cassiterite and wolframite from tin and tungsten quartz veins in portugal cassiterite and wolframite compositions from snnw and wnsn bearing quartz veins in northern and central portugal are compared to provide evidence on fluid compositions in snnw bearing quartz veins euhedral cassiterite shows sequences of alternating parallel darker and lighter zones the darker zones are pleochroic oscillatory zoned exhibit exsolutions of columbite and ixiolite and are richer in nb ta and fe than the lighter zones which consist of nearly pure sno2 cassiterite from wnsn bearing quartz veins is usually zoned with homogeneous and slightly pleochroic darker zones which are chemically similar to lighter zones bothzoneshaveinclusionsofrutileandrareilmenite thedarkerzonesofcassiteritefrom theformer veins arericherin nb taandfe contents and poorer in ti than the darker and lighter zones of cassiterite from the latter veins this is attributed to differences in the composition of magmatic hydrothermal fluids wolframite compositions from snnw and wnsn bearing quartz veins do not show any significant distinction because they precipitate from relatively similar magmatic hydrothermal fluids in some deposits most wolframite crystals are homogeneous but others are heterogeneous inner patches rich in a hubnerite component rarely occur in crystals from the filharoso and panasqueira deposits zoned crystals showing an increase in fe and a decrease in mn from core to rim were found in the vale das gatas deposit complex oscillatoryzonedcrystals occur inthe carris deposit later wolframite contains inclusions ofscheelite partially replaces itand is richer in fe and poorer in mn than earlier wolframite wolframite from snnw bearing quartz veins in the argozelo deposit and wnsn bearing quartz veins from vale das gatas and panasqueira deposits has significant nb content this does not depend on the fe and mn content of the wolframite but w content is negatively correlated with nb content only very rare single crystals of wolframite show an increase in w and a decrease in nb from core to rim snnw bearing quartz veins contain wolframite poorer in nb than the darkerzones of cassiterite which exsolved columbite andixiolite inwnsn bearing quartz veins from panasqueira and vale das gatas the wolframite has a higher nb content than the cassiterite which contains rutile inclusions enriched in nb because cassiterite and wolframite are derived from two distinct magmatic hydrothermal fluids of different age the fluid responsible for wolframite precipitationwillhaveasimilarcompositiontothatresultingfromtheevolutionofthefluidresponsibleforcassiteriteprecipitationinthe

chemical composition of rainfall and groundwater in recharge areas of the bet shean harod multiple aquifer system israel the bet shean and harod valleys are regional recipients and mixing zones for groundwaters draining from a regional multiple aquifer system comprising two different carbonate and two basalt aquifers as well as deep seated reservoirs of confined brines this paper the first of two describes the hydrochemistry of the groundwater bodies related to this multiple aquifer system the paper deals with the chemical composition of rain falling on natural recharge areas the chemical contribution of the aquifer rocks and the chemical evolution of groundwaters in the upper flow courses of all aquifers of this regional system the methodology applied is based on the determination of major dissolved ions and on the examination of their ratios and changes along the upper flow paths rain water falling on natural recharge areas has an average chlorinity of 12mgl 1cl and a calcium bicarbonate composition caused by dust borne terrigenous material this rain water salinity decreases with distance from the sea shore fresh groundwaters flowing through the different aquifers may be identified and differentiated by their characteristic salinity levels and ionic ratios groundwaters flowing through carbonate aquifers are identified by different salinity levels and by distinct rmg rca ratios reflecting dolomite calcite ratios in aquiferr rocks the groundwaters of the two basalt aquifers have typical cation assemblages and high na and mg2 concentrations far in excess of those typical of the recharging rainfall groundwater in the upper flow courses of all aquifers investigated is deficient in so2 4 and k relative to recharging rain water

ca chloride brines at common outlets of the bet shean harod multiple aquifer system israel abstract the bet shean and harod valleys are regional recipients and mixing zones for groundwaters draining into them from a multiple aquifer system which includes carbonate and basalt aquifers and deep seated reservoirs of brine the outlets of the three aquifers are located at the mountain border separating the valleys from the gilboa and ramot issakhar mts the aquifers drain through two types of outlets unique and common the latter type is mainly conditioned by the occurrence of fault blocks acting as connecting media between the aquifers upon reaching the interconnecting zones fresh groundwater flowing from carbonate and basalt aquifers intermix losing their hydrochemical identities ca chloride brines originating from deep seated and confined reservoirs leak along the deep seated faults characterizing the common outlet zones and contaminate the relatively fresh mixing products originating from the three regional aquifers two types of dilute ca chloride brines were identified in the study area the devora type is a hot and hypersaline source brine which was identified at great depth and under very high hydrostatic pressures this brine could be the residual product of seawater that evaporated during the cambrian cretaceous continental interval and subsequent prolonged interaction with surrounding carbonate rocks the neve ur type brine seems to be genetically related to the neogene inland sdom sea that preceeded the contemporary dead sea

development of the inland sea and its evaporites in the jordan dead sea transform based on hydrogeochemical considerations and the geological consequences differences in the distribution of na cl br cl and mg ca equivalent values suggest a morphotectonic barrier at marma feiyad dividing the tertiary inland sea into two basins covering the region of the jordan valley middle east depending on the tethys sea level three phases of evaporation are distinguishable that are related to three sections of the drilling log of zemah 1 in phase 1 and 3 only the northern basin was flooded during phase 2 both basins were inundated but halite mainly precipitated in the southern one the halite deposition in one or the other basin by evaporation is estimated by applying a two box model the results are constrained by the average subduction rate of 700 875 m ma and characteristic na cl values of 0 52 and 0 12 in the northern and southern basin respectively in different scenarios the sedimentation rates of halite and non halite components are varied due to assumed halokinesis reshuffling of salt and erosion of non halite sediments these simulations suggest that periods of 450 600 and 100 170 ka in the southern and northern basin were needed until the na cl values of 0 12 and 0 52 were respectively attained the inland sea most probably existed for 2 2 0 3 ma between 8 5 and 6 3 ma ago tortonian it was terminated at the beginning of the messinian crisis in all simulations the drainage flux into the southern basin exceeded that into the northern basin suggesting that the proto jordan river either did not exist at that time or did not discharge into the northern basin

high cu grades in porphyry cu deposits and their relationship to emplacement depth of magmatic sources observations at several porphyry cu deposits indicate that in those formed above source magma chambers emplaced to relatively shallow levels roofs 3 4 km deep zones of higher cu grade are associated with the oldest intrusions of a central porphyry cluster abundant early a type quartz veins secondary feldspar alteration and usually high fe fe cu low s fe cu sulfide oxide mineral assemblages in deposits for which source magma chambers were deeper roofs 5 km porphyries closest in age to ore are spatially less directly related to mineralization in these higher cu grades in early mineralization comprise swarms of veinlets with alteration halos that include sericite as well as secondary feldspar and biotite sulfide oxide assemblages are usually of lower fe fe cu and higher s fe cu these differences in deposit characteristics appear to correspond with a change from two phase chloride bearing aqueous fluids that would exsolve from magma at shallow depths to one phase fluids deeper

structure controlled groundwater flow and salinization paths in the bet she an and harod valleys israel the bet she an and harod valleys are regional recipients and mixing zones for groundwater draining to these valleys from a multiple aquifer system this aquifer system includes two different carbonate aquifers several groundwater bearing basalt flows and deep seated pressurized brine the upflow of which causes salinization of fresh groundwater bodies these aquifers drain through two groups of springs due to lack of information on the subsurface structure of the valley the flow paths of groundwater feeding the springs the initial distribution of salinities along the valley and particularly the inflow paths of the brines have never been understood but were assumed to be fault controlled the interpretation of seismic profiles and analysis of gravity anomalies revealed the subsurface structure of the valley and namely the occurrence of a dense network of faults which branch out from those delineating the jordan dead sea rift the faults formed a series of uplifted and down warped horst and graben structures by joint analysis of structural hydrological and geochemical evidence it occurs that groundwater flow paths leading to the springs emerging in the middle of the bet she an valley are determined by structural elements such as major faults and fault controlled structures the penetration of the pressurized ca chloride rift brines and their inflow into fresh groundwater bodies occurs prevalently along the faults outlining the western margins of the dead sea rift valley and at their intersection with outbranching nw se striking faults

hydrological and hydrogeochemical methods for the delineation of complex groundwater flow systems as evidenced in the bet shean valley israel abstract the bet shean valley northern israel is the base level of groundwater draining from three regional aquifers in the natural undisturbed state i e at the beginning of the six ties groundwater drained through many springs with widely different chemical composition and with a total discharge of about 135 million m 3 for the efficient utilization of water resources it was decided to recover groundwater from wells at the cost of a considerable reduction of spring discharges since the sequence and the rate of spring decay diverged from the pattern that had been predicted it became necessary to delineate aquifers and their connections to the various springs three groups of methods were employed for this purpose a analysis of discharge characteristics and their relation to source aquifers b methods for the identification of well fields that affect the discharge of a particular spring and c hydrogeochemical methods for the delineation of flow paths the paper presents the relevant data the methods employed and the results that were achieved the utility and the limitations of the various methods were discussed and general guidelines for the delineation of groundwater flow in multi aquifer systems were formulated

saline groundwaters in the canadian shield a first overview abstract the chemical and isotopic compositions of saline groundwaters and brines in the canadian shield are described the occurrence of such waters is very widespread not related to any specific rock type or mineralization and generally can be expected at depths below 1 km the most saline brines have salinities exceeding 200 g l 1 dissolved solids and their chemistries tend to suggest that in the past saline waters penetrated the canadian shield the original chemistry of these solutions was subsequently modified through strong rock water interactions and it appears that their final chemical compositions are independent of the original chemistries stable isotope analyses indicate that these waters are not simple evaporated seawater sedimentary basin brines hydrothermal solutions or residual ore forming fluids although any of these could be a precursor of the brines secondary isotope exchange reactions and the hydration of primary silicates accompanied by the formation of clay minerals could have modified not only the primary isotopic composition but may have also profoundly influenced the chemistries of these brines to be effective these processes would have had to occur in closed systems

linking mesozoic lode gold deposits to metal fertilized lower continental crust in the north china craton evidence from pb isotope systematics abstract the source s of lode gold deposits formed in precambrian cratons related to accretion collision and cratonic reactivation formerly attributed to either supercrustal volcano sedimentary sequences or deep crustal sub crustal origin remain controversial largely because gold deposits are spatially related to metamorphosed rocks but geochemical data somewhat indicate a poorly understood deep source reconciling such conflicts is important to better understand the main factor controlling the formation of ore deposits and their genetic link with specific tectonic settings giant late mesozoic lode gold provinces in the north china craton ncc were formed ca 1 7 ga later than cratonization metamorphism and contemporaneous with intensively felsic to mafic magmatism related to cratonic reactivation in this study we conduct a comprehensive pb isotope study on major gold deposits from the eastern yanshan belt northern margin of the ncc in order to constrain the source s of gold we attempt to map regional pb isotope variations of lower continental crust lcc and develop a two stage quantitative model punctuated by three prominent geological events at 2 80 ga 1 85 ga and 0 16 ga to reproduce time integrated pb isotopic signatures of deep seated lithospheric reservoirs to make a comparison with pb isotopic signatures of the gold mineralization gold bearing pyrites within different types of host rocks have relatively uniform pb isotopic ratios which are significantly different to high grade metamorphosed host rocks but similar to those of spatially associated late mesozoic granitic rocks our data show that the pb isotopic signatures of gold deposits vary consistently with presumed regional pb isotopes of the lcc during the late mesozoic lead isotopic heterogeneity of the lcc was likely caused by underplating of mafic magmas derived from mantle sources during underplating highly chalcophile elements e g au ag and cu were concentrated at the base of the lcc due to sulfide saturation from mafic magmas integrating petrological geochemical geochronological and considering chalcophile element solubility we propose a new genetic model to describe the formation of late mesozoic gold deposits in the ncc 1 early formation of sulfide bearing cumulates with high au cu ratios during magma differentiation at the base of the lcc 2 subsequent fluid fluxed remelting of these cumulates at the onset of lithospheric extension and release and ascent of ore forming fluids to the site of precipitation considering the metallogenic characteristics of other au ore forming systems we suggest that metal fertilization in deep seated reservoirs and subsequent tectonic decompression are important factors controlling the development of au rich ore deposits worldwide this study demonstrates how pb isotope can be employed to trace source s of gold deposits

coarse muscovite veins and alteration deep in the yerington batholith nevada insights into fluid exsolution in the roots of porphyry copper systems veins and pervasive wall rock alteration composed of coarse muscovite quartz pyrite are documented for the first time in a porphyritic granite at luhr hill in the yerington district nevada coarse muscovite at luhr hill occurs at paleodepths of 6 7 km in the roots of a porphyry copper system and crops out on the scale of tens to hundreds of meters surrounded by rock that is unaltered or variably altered to sodic calcic assemblages coarse muscovite veins exhibit a consistent orientation subvertical and n s striking which structurally restores to subhorizontal at the time of formation along strike coarse muscovite veins swell from distal millimeter thick muscovite only veinlets to proximal centimeter thick quartz sulfide bearing muscovite veins crosscutting relationships between coarse muscovite veins pegmatite dikes and sodic calcic veins indicate that muscovite veins are late stage magmatic hydrothermal features predating final solidification of the luhr hill porphyritic granite fluid inclusions in the muscovite quartz veins are high density aqueous inclusions of 3 9 wt nacl eq and 1 mol co2 that homogenize between 150 and 200 c similar to fluid inclusions from greisen veins in sn w mo vein systems our results indicate that muscovite forming fluids at luhr hill were mildly acidic of low to moderate salinity and sulfur content and low co2 content and that muscovite in deep veins and alteration differs in texture composition and process of formation from sericite at shallower levels of the hydrothermal system although the definition of greisen is controversial we suggest that coarse muscovite alteration is more similar to alteration in greisen type sn w mo districts worldwide than to sericitic alteration at higher levels of porphyry copper systems the fluids that form coarse muscovite veins and alteration in the roots of porphyry copper systems are distinct from fluids that formed copper ore or widespread shallower acidic alteration we propose that this style of veins and alteration at luhr hill represents degassing of moderate volumes of overpressured hydrothermal fluid during late crystallization of deep levels of the yerington batholith

acidity salinity diagrams application to greisen and porphyry deposits to a first approximation alteration minerals in greisen and related fluorine rich porphyry deposits lie in the system k 2 o al 2 o 3 sio 2 h 2 o f 2 o sub 1 equilibria in this model system can be depicted on quartz and fluid saturated chemical potential diagrams whose axes are mu hf acidity where mu hf mu hcl mu sub fcl sub 1 and mu kf salinity where mu kf mu nacl mu sub kna sub 1 mu sub fcl sub 1 advantages of this approach are that it reflects the fact that the anion f unlike cl is incorporated in greisen minerals mainly topaz fluorite and micas and that mineral stabilities can be correlated with possible ore forming processes the most important of these processes is probably vapor phase separation from an aqueous brine or magma first or second boiling fluid inclusion studies have shown that boiling occurs in all porphyry and many but not all greisen deposits vapor phase separation from a magma pneumatolysis must similarly be responsible for the formation of greisenlike mineral assemblages in miarolitic topaz rhyolite lava flows and is presumably also responsible for the formation of gem pockets in more deeply seated pegmatites and granites the result of boiling is an increase in mu hf and a decrease in mu kf in the vapor phase and the opposite in the residual brine or magma in deep greisen veins the muscovite stability field is encountered between the k feldspar and topaz fields whereas in f rich relatively shallow porphyry deposits such as henderson colorado boiling causes aqueous fluids to pass directly from the k feldspar ore zone to the overlying topaz magnetite zone muscovite or f bearing mn fe garnet is only encountered farther out as the fluids are condensed neutralized and diluted by cooler meteoric waters when ca fe mn be w o 2 s 2 and co 2 are added to the greisen model system scheelite is shown to transform to wolframite with increasing mu hf and beryl to phenakite with increasing mu hf or mu kf biotite transforms to magnetite hematite siderite pyrite chlorite or fayalite beyond the k feldspar field its stability is enhanced by high mu hf and chlorite cordierite or mn fe garnet transform to an mn fe carbonate oxide or sulfide or biotite beyond the al silicate field the ca content of plagioclase coexisting with fluorite decreases with an increase in either mu hf or mu kf and thus provides an indicator of total fluorine in both acid and neutral species

epigenetic manganese occurrences within cretaceous strata of israel epigenetic manganese mineralization occurs within cretaceous carbonate strata of israel this mineralization is structurally controlled in southern israel manganese and iron bearing waters rising along fault zones precipitated these metals as different redox conditions were encountered the manganese and associated trace metals are believed to be leached from magmatic bodies by corrosive deep seated brines in southern israel and circulating meteoric waters in northern israel

lithophile element mineralization associated with late cretaceous two mica granites in the great basin late cretaceous two mica granitoids in the great basin are closely associated with a characteristic style of lithophile element be f w mo sn and zn mineralization previously undescribed in the western united states this kind of deposit is characterized by greisenlike zones in the intrusions distinctive f and al rich skarns in carbonate rocks f deficient quartz veins in clastic rocks and distal metal bearing quartz carbonate veins mineralization can be extensive locally reaching economic grades these occurrences resemble greisen type ore deposits found in other parts of the world collectively they constitute a new metallogenic province in the western united states

definition of groundwater flow patterns by environmental tracers in the multiple aquifer system of southern arava valley israel abstract the present paper describes a model for identification and semi quantitative evaluation of the different water bodies replenishing groundwater in the southern arava rift valley the potential sources of recharge into the alluvial aquifer of the valley were assessed by multivariable cluster analysis of environmental tracers such as dissolved ions and stable isotopes this data was also used to determine the flow pattern to the valley and within its alluvial aquifer to the natural outlet of the red sea spatial variations in the chemical compositions of groundwater and of their isotopic ratios are explained as the result of differential rates of replenishment of various water bodies flowing to the arava the alluvial aquifer of the southern arava valley is recharged by the following water bodies 1 lateral subsurface flow caused by infiltration of water from flash floods occurring in the neighbouring mountain massifs 2 upward and lateral groundwater flow from sandstone and carbonate aquifers in the negev and edom mountains and 3 leakage from deep seated brine reservoirs a complete groundwater flow pattern based upon hydrological hydrochemical and isotopic data is presented in a compartmental configuration

oxygen and hydrogen isotope characteristics of hydrothermal alteration at the ann mason porphyry copper deposit yerington nevada late cenozoic normal faulting has tilted a 3 by 5 km block containing the mid jurassic ann mason porphyry copper deposit 90o w and exposed the hydrothermal alteration pattern in cross section from 1 to 6 km palcodepth oxygen and hydrogen isotopes have been used to deduce sources of hydrothermal fluids fresh samples of the host yerington batholith pluton have typical calc alkaline magmatic isotopic compositions 18 o whole rock 6 7 7 0 d biotite 85 to 88 the various types of hydrothermally altered rocks have similar d and 18 o values only slightly isotopically shifted from original magmatic values except along an axial zone within and above the orebody in this zone altered rocks are enriched in 18 o by 1 to 3 5 per mil and 18 o values increase with decreasing palcodepth the 18 o values of the whole rock and or feldspar and the d values of biotite chlorite and or actinolite in the various alteration zones are as follows propylitic alteration is widespread and is isotopically similar to fresh rock 18 o 6 2 to 7 2 per mil d 82 to 92 per mil potassic alteration characterized by 100 percent alteration of hornblende to biotite and cu mineralization occurs at 3 5 km palcodepth along the axis of the mineralizing granite porphyry dike swarm 18 o 6 5 to 8 4 per mil d 68 to 96 per mil sodic calcic alteration characterized by hydrothermal oligoclase actinolite sphene occurs laterally alongside and below the ore zone at 3 to 6 km palcodepth 18 o 5 7 to 8 4 per mil d 67 to 90 per mil late stage sodic albite chlorite alteration occurs at 1 to 4 km palcodepth in the vicinity of the axial zone 18 o 6 7 to 9 6 per mil d 79 to 85 per mil the youngest late stage sericitic alteration occurs at the shallowest levels primarily at 1 to 2 km palcodepth and displays a distinct 18 o and d enrichment 18 o 9 8 to 10 4 per mil d 61 per mil integration of stable isotope data geologic field relations and phase equilibria constraints indicates that the high salinity fluids responsible for potassic alteration and cu mineralization were of internal magmatic origin but that synchronous deep convecting saline sodic calcic fluids were largely derived from external nonmagmatic sources a third type of fluid also external but lower in temperature and much more dilute was prevalent at shallow levels and caused latestage sericitic alteration this was either an isotopically heavy coastal meteoric water or a seawater

two event lode ore deposition at butte usa 40ar 39ar and u pb documentation of ag au polymetallic lodes overprinted by younger stockwork cu mo ores and penecontemporaneous cu lodes abstract the ore genesis model for world class deposits of the butte mining district montana usa is deep pre main stage porphyry cu mo and overlying main stage ag zn cu zoned lode deposits both of which formed from hydrothermal fluids driven by minor volumes of rhyolitic magma the lode specific model is that hydrothermal processes diminished in intensity outward from district center along lode veins synchronously forming metal zones the accepted models are controverted by new geologic and multi method geochronologic studies the new data reveal the following sequence of events 1 thermal study of country rock indicates that the 76 9 ma butte granite cooled to 350 400 c by 4 m y after emplacement 2 five quartz porphyry rhyolite dikes were emplaced at 67 65 ma and another at 60 ma shrimp u pb into the cooled butte granite without resetting 40ar 39ar ages in country rock 3 fifty eight white mica and k feldspar samples from alteration envelopes adjacent to ag au polymetallic lodes in outer parts of the district zn rich lodes in intermediate parts and cu rich lodes in the district center yield 40ar 39ar ages of 73 70 ma for ag rich lodes 65 64 ma for cu rich lodes and complex age spectra of 69 65 ma for zn rich lodes the data show that ag au polymetallic lodes occupied cross district fractures by about 73 ma forming the greater butte mining district at 67 65 ma minor quartz porphyry dikes were emplaced into central and eastern parts of the rejuvenated fracture system but without evidence of related cupola or volcanic rocks or of thermal disturbance in the country rock at 64 5 ma overlapping hydrothermal cells formed two stockwork cu mo domes in deep parts of the fracture system at 65 64 ma and closely related to late stage stockwork cu mo activity a penecontemporaneous hydrothermal pulse formed a high sulfidation hydrothermal plume that 1 utilized the large re opened fractures to cannibalize and remobilize cu from autologous stockwork and older ag au polymetallic lodes 2 deposited the rich high sulfidation cu lodes and 3 mobilized metals from early ag au polymetallic veins in middle parts of the district transported the metals outward and redeposited them enriching early veins especially in the intermediate zn plus cu areas metals zones in lodes of the butte district are the result of an intensely focused cu rich hydrothermal plume that variably reworked the center of significantly larger 10 m y older ag au polymetallic lodes

brines of the siberian platform russia geochemistry and processing prospects abstract complex researches have focused on chloride brines in the large artesian basins of the siberian platform the highly concentrated ground brines are unique natural solutions that are fraught with unsolved mystery associated with their origin and the formation of their chemical composition most scientists believe that the most important process controlling the formation of these brines was interaction between palaeoseawaters and host rocks the newest geochemical and stable isotope data 18 2h 37cl 81br 87sr 86sr showed that chloride sodium ground brines of the siberian platform originated as the result of halogenous rock leaching whereas chloride calcium brines derive from buried bittern connate waters the main evolutionary process was a long interaction in the water rock system this paper also provides information on the vast resource of multicomponent brines so called liquid ores which are widespread over a large area of the siberian platform it is an unconventional hydromineral raw material whose use and exploitation has an extremely high potential as it may constitute a serious alternative to solid mineral deposits the innovative methodology and pioneering methods for the processing and extraction of valuable components especially li from brine are suggested

coarse muscovite veins and alteration in porphyry systems abstract coarse muscovite veins and alteration occur in porphyry copper and porphyry molybdenum copper systems within the laramide arc in arizona as well as at the yerington district in nevada this work describes coarse muscovite in veins and altered wall rock in porphyry systems in this region and documents mineral assemblages mineral compositions spatial and temporal relationships and hydrogen isotopic compositions coarse hydrothermal muscovite is documented in the roots of porphyry cu mo systems as well as in and above the ore bodies in porphyry mo cu systems and it is compared to coarse hydrothermal muscovite greisen in lode sn w mo systems basin and range extension has exposed coarse hydrothermal muscovite in several laramide and jurassic porphyry cu mo systems at paleodepths of 3 to 12 km miami inspiration sierrita esperanza copper basin crown king granite mountain roots of the ray porphyry system gunnison texas canyon stock grayback kelvin riverside district sycamore canyon the new cornelia mine ajo district and two systems in the yerington district muscovite is the dominant mica in these coarse muscovite veins and associated alteration with common k feldspar and albite an00 06 common accessory hematite rutile pyrite and apatite and rare accessory chalcopyrite fluorite molybdenite wolframite and scheelite coarse hydrothermal muscovite yields d compositions that suggest formation from fluids that are dominantly magmatic hydrothermal in origin whole rock compositions of coarse hydrothermal muscovite show common gains in k and loss of ca na coarse muscovite veins and alteration in porphyry copper systems postdate mineralized potassic veins and form too deeply to overlap with shallower acidic forms of alteration sericitic advanced argillic variation in mineral assemblage mineral compositions and mineralization of coarse hydrothermal muscovite correlate with the composition of laramide stocks porphyry mo cu systems contain coarse muscovite alteration assemblages with the highest mineral diversity and trace element enrichment coarse muscovite veins and alteration in porphyry mo cu systems related to stocks ranging from quartz monzonite to granite in composition form at shallower paleodepths and occur within and above the associated orebodies in contrast coarse muscovite veins and alteration associated with subalkaline porphyry copper systems occur at deeper levels in some cases overlapping with the bottom of potassic alteration and the ore body but extending well into the roots of the system in the underlying granitoid cupola in these latter systems zones of coarse muscovite alteration typically are poorly mineralized and mineral assemblages are less varied these characteristics suggest that coarse muscovite forming fluids are predominately of magmatic hydrothermal origin and exsolved from late stage fractionated magmas of the larger pluton that sourced porphyry stocks and dikes responsible for porphyry copper mineralization in some instances however the exposed coarse muscovite alteration is associated with a petrologically unrelated commonly more felsic later intrusion rather than being related to late exsolution of fluid from the same crystallizing stock or batholith

sodium calcium metasomatism chemical temporal and spatial relationships at the yerington nevada porphyry copper deposit tilting associated with extensional tectonics has exposed 1 800 m of continuous palcovertical relief through the jurassic age yerington porphyry copper deposit the rarely observed root zones of a porphyry system are characterized at yerington by sodium calcium metasomatism the principal hydrothermal reactions involve the replacement of primary k feldspar by oligoclase and of primary biotite by actinolite copper has been removed sodic calcic alteration developed at deep intrusive contacts nearly simultaneously with potassic alteration and copper mineralization at shallow intrusive contacts the reactions accompanying potassic alteration are the reverse of those accompanying sodic calcic alteration plagioclase reacted to form k feldspar hornblende reacted to form biotite the potassic and sodic calcic alteration couplet principally accompanied each of two separate intrusive events 1 luhr hill granite stock and associated porphyry dikes and 2 walker river granite porphyry dikes the younger walker river intrusion was emplaced at slightly deeper levels than the older luhr hill complex vertically stacked and partially superimposed alteration and mineralization patterns resulted from differences in depth and in timing of emplacement at lower temperatures late sodic alteration was superimposed on early sodic calcic alteration at deeper levels in the system whereas late quartz sericite pyrite alteration was superimposed on potassic alteration at higher levels sodic alteration is characterized by the replacement of k feldspar by albite and of biotite by chlorite copper deposited during potassic alteration was remobilized the transition to lower temperature alteration is associated only with the walker river intrusion the hydrothermal system associated with the emplacement of the luhr hill complex had not evolved to lower temperature assemblages prior to emplacement of the walker river dikes phase equilibria and geologic reconstruction of depth of emplacement suggest that temperatures during early sodic calcic alteration were limited to the range of 360 degrees to 480 degrees c at pressures between 300 and 800 bars late sodic alteration took place at similar pressures but at temperatures less than 360 degrees c nearly simultaneous development of potassic and sodic calcic alteration resulted from the flow of fluids away from intrusions at shallow levels potassic alteration and from the flow of fluids toward intrusions at deeper levels sodic calcic alteration because k na and na ca activity ratios of a fluid in equilibrium with granitic rocks decrease with decreasing temperature cooling of high temperature fluids can generate potassic alteration and heating of fluids to high temperatures can generate sodic or sodic calcic alteration

the rate of flushing as a major factor in determining the chemistry of water in fossil aquifers in southern israel abstract issar a 1981 the rate of flushing as a major factor in determining the chemistry of water in fossil aquifers in southern israel in w back and r letolle guest editors symposium on geochemistry of groundwater 26th international geological congress j hydrol 54 285ndash 296 a parallel trend has been found to exist between the isosalinity lines and the isopiezo metric lines in the fossil aquifers of the nubian sandstones in southern israel and the central sinai the flow pattern in these aquifers determines the rate of mixing between paleo seawater and paleo meteoric water this flowpattern is determined by the spatial relations between the nubian sandstone outcrops in the central sinai and the major fault lines of the dead sea and suez rift valleys a cumulative chemical composite diagram in which 18o stable isotope data were plotted makes it possible to classify the water and to trace the ratios in the mixture

zircon compositional evidence for sulfur degassing from ore forming arc magmas porphyry cu mo au and epithermal au ag deposits are major sources of mined metals and are commonly formed by magmatic hydrothermal fluids derived from hydrous magmas in phanerozoic convergent margin settings the igneous rock assemblages associated with porphyry mineral deposits are common in modern convergent margin settings but while many have produced acidic magmatic fluids very few past or present have produced sufficient metal chlorine and sulfur enrichments necessary to engender an ore deposit the reasons for this remain uncertain we report shrimp rg ion microprobe analyses of hafnium titanium and rare earth element ree abundances in zircon a nearly ubiquitous and robust trace mineral in crustal magmas comparison of the compositions of zircons in ore forming and barren granitic plutons indicate that ore forming granites crystallized at relatively low temperature and have relatively small negative europium anomalies mostly eu n eu n 0 4 we interpret these small zircon europium anomalies to indicate oxidizing magmatic conditions and hypothesize that in many cases this reflects oxidation due to so 2 degassing from magmas with a relatively low fe s ratio oxidation of europium and iron in the melt is produced by reduction of magmatic sulfate s 6 to so 2 s 4 upon degassing this interpretation reinforces the important role of oxidized sulfur rich fluids in porphyry and epithermal mineral deposit formation zircon compositions thus may be used to identify ancient magmas that released significant amounts of so 2 rich gases and regional surveys of zircon composition are potentially a valuable tool for mineral exploration

saline groundwater in israel its bearing on the water crisis in the country abstract one of the major causes for the deterioration of water quality bearing heavily on the water crisis in israel is the ongoing contamination of its water resources by saline water bodies the present paper reviews the geochemical processes forming saline water lists and explains certain chemical and isotopic parameters which enable understanding these processes and describes the saline groundwater bodies and various salinization phenomena occurring in the country s various aquifers deterioration of groundwater in israel is caused by numerous natural processes such as encroachment of sea water migration of connate highly pressurized brines penetrating into fresh groundwater by subsurface dissolution of soluble salts originating in surrounding country rocks and by water rock interaction in addition to sea water two saline water bodies were identified as the main factors causing salinization of fresh groundwater a ca chloride brines encountered in the jordan dead sea rift valley in various parts of the negev and of the coastal plain and b na chloride saline water identified in the subsurface of the negev and in the southern part of the coastal plain intensive exploitation of groundwater in israel has disturbed the natural equilibrium which prevailed between fresh and saline water the newly established groundwater flow regimes have facilitated the migration of saline water bodies their participation in the active hydrological cycle and the progressive contamination of fresh groundwater these processes which were not anticipated by planners and water resources managers emphasize that large scale groundwater exploitation was undertaken without giving sufficient consideration to the occurrence and subsurface migration of saline water and brines

hydrochemical changes induced by overexploitation of groundwater at common outlets of the bet shean harod multiple aquifer system israel abstract the bet shean and harod valleys are regional recipients and mixing zones for groundwaters draining into them from a multiple aquifer system which includes carbonate and basalt aquifers and deep seated reservoirs of brine the aquifers drain through two types of outlets unique and common the latter type is mainly conditioned by the occurrence of fault blocks acting as connecting media between the aquifers ca chloride brines originating from deep seated and confined reservoirs leak along the major faults and contaminate the relatively fresh groundwaters originating from the regional aquifers during the last two decades the salinity of groundwaters at the outlets of aquifers and in springs discharging into the valleys have increased as the result of overexploitation the changes in the chemical composition of these waters indicated inflow of dilute ca chloride brines which replace at an ever increasing rate the fresh water of the area the inflow of brines is limited to fault zones and seems to be controlled by the counterpressure of the overlying fresh water overexploitation diminishes this counterpressure thus facilitating the progressive upflow of brines

tectonic and regional metamorphic implications of the discovery of middle ordovician conodonts in cover rocks east of the green mountain massif vermont middle ordovician late arenigian early caradocian conodonts were recovered from a dolostone lens in carbonaceous schist 30 m below the base of the pinney hollow formation in the eastern cover sequence near west bridgewater vermont these are the first reported fossils from the metamorphic cover sequence rocks east of the green mountain berkshire and housatonic massifs of western new england the conodonts are recrystallized coated with graphitic matter thermally altered to a color alteration index cai of at least 5 and tectonically deformed the faunule is nearly monospecific consisting of abundant periodon aculeatus hadding and rare protopanderodus the preponderance of periodon and the absence of warm shallow water species characteristic of the north american midcontinent conodont province suggest a slope or basin depositional setting the conodont bearing carbonaceous schist is traceable 3 km southeast to the plymouth area where it had been designated the uppermost member of the plymout

age and paleoclimatic implications of the bet shean travertines abstract from 41 000 to over 22 000 yr b p a massive and areally extensive spring travertine was deposited in the bet shean valley israel this travertine is coeval with the ami az member of the lisan formation which represents a high lake stand the travertine deposition is contemporaneous with a more active hydrologic regime associated with wetter conditions in the arid zones of the southern levant adjacent to southern israel these wetter conditions facilitated formation of a widespread spring tufa and also enhanced the water levels of lake lisan

hydrochemistry of groundwater at unique outlets of the bet shean harod multiple aquifer system israel abstract the bet shean and harod valleys are regional recipients and mixing zones for groundwater draining to these valleys from a multiple aquifer system which includes carbonate and basalt aquifers and deep seated reservoirs of brine the outlets of these aquifers are located at the mountain border separating the valleys from the gilboa and ramot issakhar mts the aquifers drain through two types of outlets unique and common the latter type is mainly conditioned by the occurrence of fault blocks acting as connecting media between the aquifers ionic ratios of groundwaters flowing through different carbonate aquifers have not sufficient contrast to facilitate precise identification of source aquifers in the case of basalt aquifers the ratios are unequivocal and sufficient contrast enables such an identification

petrology of the yerington batholith nevada evidence for evolution of porphyry copper ore fluids the jurassic yerington batholith western nevada is a composite pluton that contains several centers of porphyry copper mineralization and is exposed in structural cross section at paleodepths ranging from 0 to 8 km within these exposures the mcleod hill quartz monzodiorite bear quartz monzonite and luhr hill granite form successive intrusions that are in turn volumetrically smaller approximately 75 19 and 6 vol respectively more deeply emplaced tops at 65 km 3 luhr hill granite the low cu content approximately 10 ppm of the granite would allow extraction of approximately 50 ppm cu from it during crystallization these data suggest an orthomagmatic model in which both high and low density saline aqueous fluids formed during exsolution of water from the crystallizing luhr hill granite and from which salts cu fe and s strongly partitioned into the high density ore fluid low density fluids may have risen from the magma as a vapor plume mineralization occurred when fluid overpressures caused fracturing of wall rock and upward intrusion of granite porphyry dikes and high density saline ore fluids both the f sub o 2 path during subsolidus cooling and the deposition of most s as chalcopyrite pyrite in ore suggest that reduction of magmatic s to sulfide may have been a mechanism for oxidation of magmatic ferromagnesian silicate and fe ti oxide minerals