hydrothermal alteration and fluid chemistry of the endako porphyry molybdenum deposit british columbia hydrothermal alteration and fluid chemistry data of the early cretaceous endako porphyry molybdenum deposit british columbia provide new information on the hydrothermal fluids associated with low fluorine molybdenite mineralization molybdenite mineralization and hydrothermal alteration occur as early quartz molydenite stockwork veins with k feldspar bearing selvages and paragenetically later quartz molybdenite ribbon veins with sericite bearing selvages late hydrothermal alteration is associated with the development of kaolinite and postore tertiary age calcite veins fluid inclusions in early formed quartz molybdenite stockwork veins with k feldspar bearing alteration assemblages are dominated by moderate salinity 5 to 15 wt nacl equiv liquid rich type 1 and rare high salinity 30 to 45 wt nacl equiv halite bearing type 3 fluid inclusions type 1 and type 3 fluid inclusions in early veins homogenize between 390 and 430 c and 375 and 420 c respectively secondary fluid inclusions type 2 of low salinity 1 to 5 wt nacl equiv in these early veins are minor and homogenize between 130 and 285 c fluid inclusions in quartz molybdenite ribbon veins with sericite bearing alteration assemblages are dominated by moderate salinity liquid rich type 1 inclusions with minor type 2 fluid inclusions type 1 fluid inclusions of ribbon veins homogenize between 360 and 400 c fluid inclusions in postore calcite veins are of only type 2 fluid inclusions which homogenize at 209 c hydrothermal fluids recorded by type 1 and type 3 fluid inclusions in early veins were trapped under lithostatic to hydrostatic conditions between 0 3 and less than or equal to 2 0 kbar and 360 and 560 c postore fluids recorded by type 2 fluid inclusions were trapped under conditions less than or equal to 0 5 kbar and between 190 and 300 c quartz stockwork and ribbon veins possess 18o values of 8 4 0 2 n 9 and 8 4 0 6 n 13 respectively hydrothermal k feldspar and biotite from k feldspar alteration assemblages possess 18o values of 6 8 0 4 n 7 and 3 5 0 8 n 8 respectively oxygen isotope geothermometry of quartz biotite and quartz k feldspar pairs from k feldspar alteration assemblages yield temperatures between 200 and 490 c which is similar to the trapping temperatures of hydrothermal fluids determined from fluid inclusion studies associated with molybdenite mineralization the development of kaolinite and calcite veins the oxygen isotope temperatures of the quartz biotite and quartz k feldspar pairs suggest that k feldspar and biotite either record the approximate 18o composition of hydrothermal fluids associated with k feldspar alteration or have undergone 18o exchange with late stage hydrothermal fluids hydrogen isotope composition of quartz stockwork and ribbon veins fluid inclusion waters range between 105 and 173 per mil solute chemistry studies of fluid inclusion waters indicate that ore forming fluids from endako have low br cl and br na ratios and high i cl and i br ratios in comparison to porgera epithermal babine lake porphyry cu and st austell capitan pluton vein deposits associated with magmatic processes na k ratios of fluid inclusion waters yield temperatures 308 to 429 c similar to those determined from type 1 and type 3 fluid inclusions and stable isotope thermometry results from fluid inclusion and solute chemistry studies indicate the involvement of hydrothermal fluids exsolved from a crystallizing melt in the formation of the endako molybdenum deposit however oxygen and hydrogen isotope values deviate from the generally accepted magmatic compositions which suggests the early involvement of meteoric water in the ore forming fluids and ore genesis

the evolution of tungsten sources in crustal mineralization from archean to tertiary inferred from lead isotopes lead isotope compositions of 31 tungsten bearing mineral occurrences worldwide with ages ranging be tween archean and tertiary have been determined to assess the evolution of tungsten sources in crustal min eralization through time the data indicate that tungsten of crustal mineralization was mainly supplied by the mantle between 3 0 and 2 4 ga the possibility of increasing contributions from the newly formed crust to tungsten mineralization throughout the archean is suggested by the available data although this suggestion needs to be tested by additional measurements the tungsten occurrences of proterozoic age contain mature crustal lead reflecting their association with crustal reworking through metamorphism and magmatism in the proterozoic mobile belts from 0 5 ga onward tungsten mineralization displays a renewed mantle lead con tribution owing to the direct or indirect association of post 0 5 ga tungsten occurrences with subduction re lated magmatic rocks of the phanerozoic orogenic cycles the data presented also suggest that several tungsten mineralization pulses may have recycled tungsten from older reservoirs

reassessment of continental growth during the accretionary history of the central asian orogenic belt we argue that the production of mantle derived or juvenile continental crust during the accretionary history of the central asian orogenic belt caob has been grossly overestimated this is because previous assessments only considered the palaeozoic evolution of the belt whereas its accretionary history already began in the latest mesoproterozoic furthermore much of the juvenile growth in central asia occurred in late permian and mesozoic times after completion of caob evolution and perhaps related to major plume activity we demonstrate from zircon ages and nd hf isotopic systematics from selected terranes within the caob that many neoproterozoic to palaeozoic granitoids in the accreted terranes of the belt are derived from melting of heterogeneous precambrian crust or through mixing of old continental crust with juvenile or short lived material most likely in continental arc settings at the same time juvenile growth in the caob occurred during the latest neoproterozoic to palaeozoic in oceanic island arc settings and during accretion of oceanic island arc and precambrian terranes however taking together our data do not support unusually high crust production rates during evolution of the caob significant variations in zircon ehf values at a given magmatic age suggest that granitoid magmas were assembled from small batches of melt that seem to mirror the isotopic characteristics of compositionally and chronologically heterogeneous crustal sources we reiterate that the chemical characteristics of crustally derived granitoids are inherited from their source s and cannot be used to reconstruct tectonic settings and thus many tectonic models solely based on chemical data may need re evaluation crustal evolution in the caob involved both juvenile material and abundant reworking of older crust with varying proportions throughout its accretionary history and we see many similarities with the evolution of the sw pacific and the tasmanides of eastern australia

geological and industrial implications of extensive dilatancy anisotropy extensive dilatancy anisotropy is the hypothesized distribution of stress aligned fluid filled microcracks pervading most rocks in the earth s crust the geometry of the cracks and the aligning stress field can be monitored by analysing the waveforms of shear waves propagating through the rockmass the ability to estimate some of the parameters of the crack and stress geometry by analysing shear wave particle displacements has widespread implications

imaging fractures and sedimentary fabrics using shear wave splitting measurements made on passive seismic data summary the ability to detect aligned fractures using seismic anisotropy provides a valuable tool for exploiting hydrocarbon reservoirs better perhaps the most direct way of identifying anisotropy is by observing shear wave splitting however the interaction of shear waves with subsurface structure is often complicated although fractures in hydrocarbon reservoirs are usually subvertical shear waves recorded on downhole receivers from microseismic events in or near the reservoir are not likely to have travelled vertically as such interpreting splitting measurements made on such waves is a non trivial problem here we develop an approach to model the effects of subsurface structure on non vertically propagating shear waves rock physics theory is used to model the effects of sedimentary fabrics as well as fractures allowing us to use shear wave splitting measurements to invert for aligned fractures we use synthetic examples to demonstrate how it is possible to assess in advance how well splitting measurements will image structures and how this is highly dependent on the available range of ray coverage finally we demonstrate the inversion technique on a passive seismic data set collected during hydraulic fracture stimulation despite an unfavourable source receiver geometry the strike of an aligned fracture set is accurately identified

peraluminous i type granites abstract s type granites always contain more al than the amounts of na ca and k in the rock required to form feldspars primarily owing to their derivation from source components that had previously been weathered those rocks are therefore always saturated in al or peraluminous many i type granites are also peraluminous despite i type source rocks typically not being saturated in al it has previously been suggested that this may result from the fractional crystallisation of amphibole however data from compositionally zoned high temperature plutons in the lachlan fold belt show that it is difficult to generate large quantities of peraluminous melt by removal of amphibole most of the i type granites 95 in the lachlan fold belt formed at lower temperatures and almost half of those rocks for which bulk chemical compositions are available are peraluminous among these granites there are 98 separate suites for which there are chemical data for two or more samples with 47 suites that include both metaluminous more mafic and peraluminous more felsic compositions the origin of those peraluminous compositions is fundamental to any understanding of i type granite petrogenesis in this region compositional variations caused by the assimilation or by partial melting of supracrustal rocks are very small as the isotopic variations within these rocks are dominantly between different suites not within suites the partial melting of more mafic source rocks rather than the fractional crystallisation of more mafic magmas is favoured for the origin of these rocks partial melting is the most likely process involved in the petrogenesis of felsic granites where broadly granodioritic monzogranitic batholiths are associated with lesser amounts of tonalite and very minor amounts of mafic rock experimental studies have shown that the melts generated by the partial melting of basaltic to andesitic rocks under crustal conditions are mostly peraluminous during the dehydrational melting of i type granite source rocks at pressures below the garnet stability field biotite and amphibole melt incongruently to yield pyroxenes the excess al is incorporated into the felsic liquid resulting in the generation of peraluminous melts in this instance the excess al in felsic i type granites is a function of the melting process and unrelated to the bulk composition of the source the observed gradation from peraluminous felsic granites to metaluminous compositions in less felsic rocks in largely isotopically closed systems could happen in two ways at higher temperatures of partial melting ca and other components of clinopyroxene could dissolve in the melt with the melt eventually becoming metaluminous alternatively minerals residual from partial melting dominantly pyroxenes and plagioclase could be incorporated in suspension in the melt so that the resulting bulk magma is metaluminous examples of these two extremes and of intermediate cases are well developed among the granites of southeastern australia

synthetic fluid inclusions viii vapor saturated halite solubility in part of the system nacl cacl2 h2o with application to fluid inclusions from oceanic hydrothermal systems abstract halite solubility along part of the vapor saturated liquidus in the system nacl cacl 2 h 2 o has been determined using the synthetic fluid inclusion technique data allow the construction of liquidus isotherms for temperatures up to 500 c and bulk compositions containing 60 wt total salt and as much as 25 wt cacl 2 combined with previous data for the binary system nacl h 2 o and for the ternary system nacl cacl 2 h 2 o in the low salinity low temperature region a preliminary ternary phase diagram can be constructed that remains incomplete only in the cacl 2 rich region results are applied to the interpretation of saline fluid inclusions from quartz veins in oceanic metagabbros and can be applied to many other natural inclusions containing aqueous solutions with nacl and cacl 2 the dominant solutes microthermometric measurements at equilibrium of the melting temperature of ice tm ice and of the dissolution temperature of halite tm halite are sufficient to determine the bulk composition of the nacl cacl 2 h 2 o fluid

evaluation of anisotropy by shear wave splitting the polarizations of three component shear wavetrains carry unique information about the internal structure of the rock through which they pass specifically commonly observed shear wave splitting may contain information about the orientation of crack distributions this information cannot usually be recovered from shear waves recorded at the free surface because of interference with the interaction of the shear wave with the surface even for nearly vertical incidence however shear wave splitting in synthetic three component vertical seismic profiles in some cases may be interpreted directly in terms of the direction of strike of vertical cracks because the human eye is not skilled at identifying the phase relationships between three component seismograms played out conventionally as parallel time series the polarizations are displayed in orthogonal sections of the particle displacements to facilitate recognition and evaluation of the shear wave splitting estimating the orientations of cracks an

an integrated study of seismic anisotropy and the natural fracture system at the conoco borehole test facility kay county oklahoma a significant body of published work has developed establishing fracture related seismic anisotropy as an observable effect to further the understanding of seismic birefringence techniques in characterizing natural fracture systems at depth an integrated program of seismic and geologic measurements has been conducted at conoco s borehole test facility in kay county oklahoma birefringence parameters inferred from the seismic data are consistent with a vertical fracture model of density 0 04 striking east northeast that direction is subparallel to a fracture set mapped both on the surface and from subsurface data to the in situ maximum horizontal stress and to the inferred microfabric

fracture detection using crosshole surveys and reverse vertical seismic profiles at the conoco borehole test facility oklahoma summary shear waves in combined crosshole surveys chss and reverse vertical seismic profiles rvsps at the conoco borehole test facility oklahoma are analysed to examine the relationship between shear wave propagation and natural fracture systems the surveys cover a range of azimuths and angles of incidence and give the possibility of studying fracture induced azimuthal anisotropy in some detail the data display several features characteristic of seismic anisotropy shear wave splitting displaying substantial time delays up to 7 ms for source geophone distances of less than 50 m suggest large fracture densities estimates of fast shear wave polarizations and time delays confirm the n75de 10d fracture strike deduced from other geological and hydrological observations analyses of chs data including modelling with synthetic seismograms suggest that at least the dominant fracture set is rotated by 20d from the vertical one of the most important results of this study is the positive identification of guided waves propagating between wells along interfaces with sufficient velocity constrast in chs profiles it appears that combinations of chss and rvsps offer unique possibilities in evaluating fracture parameters at shallow depths this could be important for the study of fluid flow at shallow depths in hydrological investigations

effects of the internal shear wave window comparison with anisotropy induced splitting in the absence of anisotropy the observed polarizations of shear waves should be those radiated from the source modified only by interaction with internal interfaces and free surface topography it has been suggested that shear wave polarizations may be systematically distorted by internal interfaces which could lead to difficulties in interpreting anisotropy induced shear wave splitting since the literature now reports many investigations of shear wave splitting possible complications caused by internal interfaces would be important and need to be assessed in this paper we investigate the polarization of shear waves in full wave synthetic seismograms incident from a point source at an isotropic to isotropic interface over a range of angles of incidence particle motion due to plane and curved wave fronts has different characteristics internal shear wave windows can be defined analogous to the shear wave window at the free surface within the innermost window the polarizations at subsurface geophones as in vertical seismic profiles are recorded with little distortion but outside this window the waveforms become increasingly distorted for larger angles of incidence this is similar to the behavior of shear waves with respect to the shear wave window at the free surface except that the behavior at internal interfaces is more complicated because of additional critical angles and additional windows we conclude that the interaction of shear waves with internal interfaces is only a serious difficulty when interpretating wide offset vertical seismic profiles wide angle reflections and cross hole data

geology mineralization and fluid inclusion characteristics of the kashkasu w mo cu skarn deposit associated with a high potassic to shoshonitic igneous suite in kyrgyzstan tien shan toward a diversity of w mineralization in central asia abstract the kashkasu deposit is part of the subduction related late paleozoic late carboniferous metallogenic belt of tien shan it is associated with a multiphase monzodiorite monzonite granodiorite granite pluton of the magnetite series high k calc alkaline to shoshonitic igneous suite the deposit contains zones of w mo cu oxidized prograde and retrograde skarns with abundant andraditic garnet magnetite locally scapolite and k feldspar as well as scheelite chalcopyrite and molybdenite skarns are overprinted by quartz carbonate sericite phyllic alteration zones with scheelite and sulfides prograde calcic skarn and initial retrograde skarns were formed from a high temperature 650 c to 450 550 c high pressure 2000 bars to 600 900 bars magmatic hydrothermal low to high salinity aqueous chloride fluid the gradual fluid evolution was interrupted by the intrusion of granodiorite and likely associated release of low salinity 7 8 wt nacl equiv fluid ascent of this fluid to shallower levels and or its cooling to 400 500 c has resulted in phase separation into low salinity 2 1 3 1 wt nacl equiv vapor and coexisting brine 35 40 wt nacl equiv the boiling was coincident with most intense scheelite deposition in retrograde skarn later retrograde skarn assemblages were formed from a gaseous low to moderate salinity 3 4 8 1 wt nacl equiv fluid and then from high salinity 37 42 wt nacl equiv aqueous chloride fluids the latter being enriched in ca 17 20 wt cacl2 that could also affect scheelite deposition another cycle of fluid exsolution from crystallizing magma corresponded to quartz carbonate sericite scheelite sulfide phyllic alteration stage with the early low salinity 5 3 8 4 wt nacl equiv fluid followed by later high salinity 33 5 38 2 wt nacl equiv fluid the sulfur isotope data 34s 5 1 to 9 0 suggest significant sulfur sourcing from sedimentary rocks enriched in seawater sulfate possibly evaporites

multicomponent near surface correction for land vsp data multicomponent seismic data collected using directional sources are degraded by the wave excitation process due to inaccurate control of the ground motion unequal activation strengths or ground couplings between differently oriented sources and misalignment of the pad these acquisition uncertainties are exacerbated by the complicated near surface scattering present in most seismic areas neither group of effects should be neglected in multicomponent analyses that make use of relative wavefield attributes derived from compressional and shear waves these effects prevent analysis of the direct and reflected waves using procedures based on standard scalar techniques or a prima facia interpretation of the vector wavefield properties even for the seemingly straightforward case of a near offset vertical seismic profile vsp near surface correction using a simple matrix operator designed from the shallowest recordings alleviates many of these interpretational difficulties in near offset vsp data results from application of this technique to direct waves from a nine component vsp shot at the conoco test site facility oklahoma are encouraging the technique corrects for unexpected compressional wave energy from shear wave vibrators and collapses near surface multiples thus facilitating further processing for the upgoing wavefield the method provides a simple and effective processing step for routine application to near offset vsp analyses

architecture and mineral deposit settings of the altaid orogenic collage a revised model abstract the altaids are an orogenic collage of neoproterozoic paleozoic rocks located in the center of eurasia this collage consists of only three oroclinally bent neoproterozoic early paleozoic magmatic arcs kipchak tuva mongol and mugodzhar rudny altai separated by sutures of their former backarc basins which were stitched by new generations of overlapping magmatic arcs in addition the altaids host accreted fragments of the neoproterozoic to early paleozoic oceanic island chains and neoproterozoic to cenozoic plume related magmatic rocks superimposed on the accreted fragments all these assemblages host important many world class late proterozoic to early mesozoic gold copper molybdenum lead zinc nickel and other deposits of various types in the late proterozoic during breakup of the supercontinent rodinia the kipchak and tuva mongol magmatic arcs were rifted off eastern europe siberia and laurentia to produce oceanic backarc basins in the late ordovician the siberian craton began its clockwise rotation with respect to eastern europe and this coincides with the beginning of formation of the mugodzhar rudny altai arc behind the kipchak arc these earlier arcs produced mostly cu pb zn vms deposits although some important intrusion related orogenic au deposits formed during arc arc collision events in the middle cambrian and late ordovician the clockwise rotation of siberia continued through the paleozoic until the early permian producing several episodes of oroclinal bending strike slip duplication and reorganization of the magmatic arcs to produce the overlapping kazakh mongol and zharma saur valerianov beltau kurama arcs that welded the extinct kipchak and tuva mongol arcs this resulted in amalgamation of the western portion of the altaid orogenic collage in the late paleozoic its eastern portion amalgamated only in the early mesozoic and was overlapped by the transbaikal magmatic arc which developed in response to subduction of the oceanic crust of the paleo pacific ocean several world class cu mo porphyry cu pb zn vms and intrusion related au mineral camps which formed in the altaids at this stage coincided with the episodes of plate reorganization and oroclinal bending of magmatic arcs major pb zn and cu sedimentary rock hosted deposits of kazakhstan and central asia formed in backarc rifts which developed on the earlier amalgamated fragments major orogenic gold deposits are intrusion related deposits often occurring within black shale bearing sutured backarc basins with oceanic crust after amalgamation of the western altaids this part of the collage and adjacent cratons were affected by the siberian superplume which ascended at the permian triassic transition this plume related magmatism produced various deposits such as famous ni cu pge deposits of norilsk in the northwest of the siberian craton in the early mesozoic the eastern altaids were oroclinally bent together with the overlapping transbaikal magmatic arc in response to the northward migration and anti clockwise rotation of the north china craton the following collision of the eastern portion of the altaid collage with the siberian craton formed the mongol okhotsk suture zone which still links the accretionary wedges of central mongolia and circum pacific belts in the late mesozoic a system of continent scale conjugate northwest trending and northeast trending strike slip faults developed in response to the southward propagation of the siberian craton with subsequent post mineral offset of some metallogenic belts for as much as 70 400 km possibly in response to spreading in the canadian basin india asia collision rejuvenated some of these faults and generated a system of impact rifts

algebraic processing techniques for estimating shear wave splitting in near offset vsp data theory1 a vector convolutional model for multicomponent data acquired in an anisotropic earth is used as a basis for developing algebraic solutions to interpret near offset vsp data this interpretation of the cumulative or interval medium response green s tensor for shear waves determines a polarization azimuth for the leading shear wave and the time delay between the fast and slow split waves the algebraic solutions effectively implement least squares eigenanalysis or singular value decomposition although the methodology for shear wave analysis is strictly relevant to a transmission response it can be adapted to surface data for a uniform anisotropic overburden the techniques perform well when calibrated and tested using synthetic seismograms from various anisotropic models noise tests demonstrate the sensitivity of the interval measurements to local interferences particularly if the shear waves are generated by one source although the algorithms are faster than numerical search routines this is not seen as their major advantage the solutions may have potential in near real time interpretation of shear wave data in well logging where they may be coded on a microchip to provide a direct stream of separated shear waves or polarization and birefringence information there may also be some benefit for large prestack multicomponent surface data sets where the solutions provide a direct transformation to the split shear wave components reducing the storage space for further processing

inverting shear wave polarizations for anisotropy using three component offset vsps synthetic seismograms summary a numerical algorithm is presented for interpreting shear wave polarization directions from offset vsp data as subsurface anisotropy the technique compares observed synthetic horizontal polarization angles with expected values for a range of physically plausible anisotropic models with different orientations the comparison is implemented in a database inversion scheme the anisotropic models are formed by combining the effective anisotropy of parallel aligned vertical cracks with matrix anisotropy due to thin layering or lithology different models are defined by varying the crack and matrix properties the technique is applied to synthetic offset vsp data for a multilayered anisotropic structure generated by multi azimuth sources analysis of the results indicates that polarization measurements from non zero offsets with at least two and preferably three different azimuths are required in order to reasonably constrain the final inversion solutions the parameters which are resolved depend upon the depth of the subsurface zone of interest crack strike is well resolved in the deeper layers for which directions of propagation are sub vertical whereas other model parameters such as aspect ratio and crack content can only be resolved for wider ranges of incidence angle the key to a successful inversion appears to lie in the selection of propagation paths through the relatively unique patterns of disruption created by singularities

fracture characterization from near offset vsp inversion a global optimization method incorporating a ray tracing scheme is used to invert observations of shear wave splitting from two near offset vsps recorded at the conoco borehole test facility kay county oklahoma inversion results suggest that the seismic anisotropy is due to a non vertical fracture system this interpretation is constrained by the vsp acquisition geometry for which two sources are employed along near diametrically opposite azimuths about the well heads a correlation is noted between the time delay variations between the fast and slow split shear waves and the sandstone formations

shear wave anisotropy and the stress field from borehole recordings at 2 5 km depth at cajon pass summary 53 local earthquakes recorded at 2 5 km depth in the cajon pass scientific borehole are analysed for shear wave splitting the time delays between the split shear waves can be positively identified for 32 of the events modelling these observations of polarizations and time delays using genetic algorithms suggests that the anisotropic structure near cajon pass has orthorhombic symmetry the polarization of the shear waves and the inferred strike of the stress aligned fluid filled intergranular microcracks and pores suggests that the maximum horizontal compressional stress direction is approximately n13 w this is consistent with previous results from earthquake source mechanisms and the right lateral strike slip motion on the nearby san andreas fault but not with stresses measured within the uppermost 3 km of the borehole this study suggests that the san andreas fault is driven by deeper tectonic stresses and the present understanding of a weak and frictionless san andreas fault may need to be modified the active secondary faulting and folding close to the fault are probably driven by the relatively shallow stress as measured in the 3 5 km deep borehole

reconciling fluid inclusion types fluid processes and fluid sources in skarns an example from the bismark deposit mexico the bismark deposit 8 5 mt at 8 zn 0 5 pb 0 2 cu and 50 g t ag located in northern mexico is an example of a stock contact skarn end member of a continuum of deposit types collectively called high temperature carbonate replacement deposits the deposit is hosted by massive sulfide within altered limestone adjacent to the bismark quartz monzonite stock 42 ma and the bismark fault alteration concurrently developed in both the intrusion and limestone the former contains early potassic alteration comprising k feldspar and biotite which was overprinted by kaolinite rich veins and alteration and later quartz sericite and pyrite with minor sphalerite and chalcopyrite prograde exoskarn alteration in the limestone consists of green andradite and diopside and transitional skarn comprising red brown andradite green hedenbergite and minor vesuvinite calcite fluorite and quartz the main ore stage post dates calc silicate minerals and comprises sphalerite and galena with gangue pyrite pyrrhotite calcite fluorite and quartz the entire hydrothermal system developed synchronously with faulting fluid inclusion studies reveal several distinct temporal compositional and thermal populations in pre syn and post ore quartz fluorite and calcite the earliest primary fluid inclusions are coexisting vapor rich type 2a and halite bearing type 3a type 3b contain sylvite brine inclusions 32 to 60 total wt salts that occur in pre ore fluorite trapping temperatures are estimated to have been in excess of 400 c under lithostatic pressures of 450 bar 1 5 km depth primary fluid inclusions trapped in syn ore quartz display critical to near critical behavior type 1c have moderate salinity 8 4 to 10 9 wt nacl equiv and homogenization temperatures th ranging from 351 to 438 c liquid rich type 1a and 1b calcite bearing inclusions occur as primary to secondary inclusions predominantly in fluorite and show a range in th 104 336 c and salinity 2 7 11 8 wt nacl equiv which at the higher th and salinity ranges overlap with type 1c inclusions oxygen isotope analysis was carried out on garnet quartz and calcite plus carbon isotopes in pre syn post ore and peripheral veins pre ore skarn related garnets have a 18omineral range between 3 9 and 8 4 quartz from the main ore stage range between 13 6 and 16 0 calcite from the main ore stage has 13c values of 2 9 to 5 1 and 18o values of 12 3 to 14 1 which are clearly distinct from post ore veins and peripheral prospects that have much higher 18o 16 6 27 3 and 13c 1 3 3 1 values despite the numerous fluid inclusion types only two fluid sources can be inferred namely a magmatic fluid and an external fluid that equilibrated with limestone furthermore isotopic data does not indicate any significant mixing between the two fluids although fluid inclusion data may be interpreted otherwise thus the various fluid types were likely to have formed from varying pressure temperature conditions through faulting during exsolution of magmatic fluids late stage hydrothermal fluid activity was dominated by the non magmatic fluids and was post ore

evidence of sea ice source in aerosol sulfate loading and size distribution in the canadian high arctic from isotopic analysis the influence of frost flowers and seawater brine on ion chemistry in snow snowpack ice cores and aerosols is detected when a lower sulfate to sodium ratio than in seawater is present in polar regions this evidence can be masked when large amounts of non sea salt sulfate are present from other sources such as biogenic and anthropogenic sulfate frost flower 34s values were measured for the first time in frost flower sulfates and did not differ significantly from the sea salt 34s values of 21 a method using stable isotopes is introduced to determine the limit of contributions from sea salt and sea ice sources including frost flowers and brine on sulfate concentrations in aerosol samples from alert canada knowledge of the range of values of 34snss and the so4 na ratio found in sea ice sources i e frost flowers is used to quantitatively constrain the contributions from frost flowers and sea salt in the arctic aerosol mass during the onset of winter in 2007 and 2008 allowing for quantification of non sea salt sulfate amounts during times when frost flowers are present frost flower and or brine influence was found predominantly in the coarse mode aerosols 0 95 m this method to determine the contributions from sea salt and sea ice sources can be carried over to future studies with snow and ice cores

seismic anisotropy in granite at the underground research laboratory manitoba the shear wave experiment at atomic energy of canada limited s underground research laboratory was probably the first controlled source shear wave survey in a mine environment taking place in conjunction with the excavation of the mine by test tunnel at 420 m depth the shear wave experiment was designed to measure the in situ anisotropy of the rockmass and to use shear waves to observe excavation effects using the greatest variety of raypath directions of any in situ shear wave survey to date inversion of the shear wave polarizations shows that the anisotropy of the in situ rockmass is consistent with hexagonal symmetry with an approximate fabric orientation of strike 023 degree and dip 35 degree the in situ anisotropy is probably due to microcracks with orientations governed by the in situ stress field and to mineral alignment within the weak gneissic layering however there is no unique interpretation as to the cause of the in situ anisotropy as the fabric orientation agrees approximately with both the orientation expected from extensive dilatancy anisotropy and that of the gneissic layering eight raypaths with shear waves propagating wholly or almost wholly through granodiorite rather than granite do not show the expected shear wave splitting and indicate a lower in situ anisotropy which maymore be due to the finer grain size and or the absence of gneissic layering within the granodiorite these results suggest that shear waves may be used to determine crack and mineral orientations and for remote monitoring of a rockmass this has potential applications in mining and waste monitoring less

seasonal variations of snow chemistry at neem greenland we conducted a pit study in july 2009 at the neem north greenland eemian ice drilling deep ice coring site in northwest greenland to examine the seasonal variations of snow chemistry and characteristics of the drill site we collected snow firn samples from the wall of a 2 m deep pit at intervals of 0 03 m and analyzed them for electric conductivity ph cl no3 so 4 2 ch 3 so 3 msa na k mg 2 ca 2 and stable isotopes of water 18 o and d pronounced seasonal variations in the stable isotopes of water were observed which indicated that the snow had accumulated regularly during the past 4 years concentrations of na cl and mg 2 which largely originate from sea salt peaked in winter to early spring while ca 2 which mainly originates from mineral dust peaked in late winter to spring slightly later than na cl and mg 2 concentrations of no 3 showed double peaks one in summer and the other in winter to spring whereas those of so 4 2 peaked in winter to spring the winter to spring concentrations of no 3 and so 4 2 seem to have been strongly influenced by anthropogenic inputs concentrations of msa showed double peaks one in spring and the other in late summer to autumn our study confirms that the neem deep ice core can be absolutely dated to a certain depth by counting annual layers using the seasonal variations of stable isotopes of water and those of ions we calculated the annual surface mass balance for the years 2006 08 the mean annual balance was 176 mm w e and the balances for winter to summer and summer to winter halves of the year were 98 and 78 mm respectively snow deposition during the winter to summer half of the year was greater than that during the summer to winter half by 10 20 mm for all three years covered by this study

fluid inclusions in epidote minerals and fluid development in epidote bearing rocks the widespread occurrence of epidote minerals in metamorphic and igneous rocks as well as in many ore deposit types makes it a promising candidate for fluid inclusion studies apart from high to very high temperature and low to intermediate pressure conditions epidote minerals are stable over a wide range of pressure and temperature in the continental and oceanic crust e g poli and schmidt 1998 yet fluid inclusion studies on epidote minerals are surprisingly scarce even in fluid saturated environments like certain vein type deposits or hydrothermal volcanic vugs and druses for example epidote minerals are not mentioned in the subject index of roedder s 1984 outstanding summary and review of fluid inclusion studies and occurrences which lists more than sixty different host minerals for fluid inclusions nonetheless more recent studies showed fluid inclusions in epidote minerals to be the only direct witness of the physiochemical and compositional fluid evolution during certain geodynamic processes mainly found in fossil geothermal systems ore deposits and high pressure to ultra high pressure rocks the aim of this review is to outline and summarize some aspects and interpretations of geodynamic processes which are based on temperature t pressure p molar volume v and composition x data from fluid inclusions in epidote minerals as well as associated host minerals from various geological environments the review starts with a chapter on some typical mixed volatile solid fluid equilibria involving epidote minerals which are relevant for the here discussed environments this is followed by a short introduction into the basic concepts of fluid inclusion research and the role of epidote minerals the next section covers fluid inclusion studies on epidote minerals from active and fossil geothermal systems as well as low grade metamorphic rocks and constraints on the p t x properties of the fluids present in these systems this is followed by a short introduction

crack distributions which account for a given seismic anisotropy summary the effect of microfractures or small scale inclusions within earth structures may be measured seismically wavespeeds as a function of wave normal direction lead to effective or mean elastic parameters and the difference between these and the values for unfractured material is related to parameters for the size distribution and internal conditions of the cracks or inclusions thus it appears that measurement of the seismic wavespeeds for a sequence of different propagation directions can lead to information about fractures or inclusions within the rock even though the scale size of this microstructure may be very small compared with a wavelength however the crack parameters are continuous functions of orientation and the elastic parameters for the material provide values for only 21 independent quantities this is enough to describe the crack distribution in terms of spherical surface harmonics up to fourth order only the relationship between the effective elastic parameters and t he crack distribution is accurate to second order in the number density which limits the applications to materials where the contribution of microfractures is less than 10 per cent the relationships referred to above show that inherent material anisotropy is equivalent to a distribution of hypothetical cracks embedded in an isotropic material it then follows that the effect of microfractures in an anisotropic solid may be calculated by imposing both systems of cracks real and hypothetical on an isotropic matrix for which solutions are known

spatial patterns and seasonal variation of snowpack sulphate isotopes of the prince of wales icefield ellesmere island canada ion chemistry and sulphate isotope values for snow samples from the prince of wales icefield ellesmere island canada show distinct seasonal trends and spatial patterns sixteen surface snow samples from two transects and 30 samples from five depth profiles representing fall 2003 to spring 2004 accumulation have been analyzed surface snow samples show decreasing so4 2 and na concentrations along with decreasing d 34 s values with distance inland and increased elevation these trends follow an expected pattern of decreasing sea salt aerosol impact with greater vertical and horizontal distance from sea water sources depth profile total sulphate and non sea salt sulphate increase in concentration with height in the snowpack and these results combined with d 34 s values that are more positive in fall snow are consistent with increased amounts of anthropogenic sulphate in surface spring snow sulphate apportionment was performed on surface snow assuming an isotopically light sulphate source anthropogenic plus volcanic mixed with isotopically heavier sulphate from dimethylsulphide dms oxidation and sea water isotopically light sulphate in surface snow was apparent at all elevations at a reasonably uniform concentration dms sulphate however decreased exponentially with altitude reflecting an ocean level source with oxidation occurring during transport and deposition the significance to multi year deposition studies is that sulphate from dms oxidation may be related to sea ice conditions in the region

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

east antarctic ice core sulfur isotope measurements over a complete glacial interglacial cycle 1 both sulfur and oxygen isotopes of sulfate preserved in ice cores from greenland and antarctica have provided information on the relative sources of sulfate in the ice and their chemical transformation pathways in the atmosphere over various time periods the mass independent fractionation in the oxygen isotopes of sulfate from the vostok ice core from east antarctica suggests that gas phase oxidation by the hydroxyl radical oh was relatively greater than aqueous phase oxidation by o3 and h2o2 during the last glacial period than during the eemian and preindustrial holocene the complete sulfur isotopic composition 33s 34s 36s from the same vostok ice core samples along with 34s measurements from the dome c east antarctic ice core from this study lend support to these conclusions and reveal significant isotopic fractionation of 34s during chemical transformation and transport to east antarctica these findings reveal that conservation of sulfur isotopic signatures upon transport cannot be assumed for the east antarctic plateau over the time periods considered

direct evolution of brine from a crystallizing silicic melt at the questa new mexico molybdenum deposit molybdenum mineralization in the southwest orebody at the questa deposit is associated with crystallization of aplite porphyry explosive brecciation and exsolution of magmatic hydrothermal fluids quartz k feldspar fluorophlogopite and molybdenite precipitated from exsolving aqueous fluids and cemented aplite porphyry and andesite wall rock clasts forming a magmatic hydrothermal breccia ore fluid inclusions in quartz in the breccia matrix trapped aqueous fluids that transported and precipitated molybdenum two fluid inclusion populations associated with molybdenite mineralization were identified the largest population commonly contains liquid vapor halite sylvite and one or more opaque daughter crystals these inclusions homogenize between 200 degrees and 500 degrees c and have a prominent mode at 360 degrees to 400 degrees c salinities vary from 31 to 57 wt percent nacl equiv low first ice melting temperatures suggest that additional fluid components possibly calcium or magnesium chlorides may be present approximately 80 percent of these inclusions homogenize by halite dissolution phase equilibria constraints require that these inclusions trapped fluids in the vapor absent field the remaining saline inclusions homogenize to liquid at temperatures above halite dissolution temperatures significantly the saline fluid did not coexist with a low density aqueous fluid a second population of inclusions contains fluids with salinities of 2 7 to 25 0 wt percent nacl equiv and homogenizes by vapor bubble disappearance vapor bubble expansion or critical behavior textural relationships and phase behavior during microthermometry indicate that these inclusions constitute a single population which formed as pressure and temperature fluctuated at near critical conditions pressure changes related to brecciation followed by crystallization and system resealing produced the observed fluids saline fluids were trapped as the system sealed following a major brecciation event these high salinity fluids were produced as the melt under pressure that increased from hydrostatic to lithostatic partitioned increasing amounts of chlorine into the exsolving aqueous fluid renewed fracturing and abrupt pressure decrease to hydrostatic conditions reduced the mass of chlorine partitioning to the exsolving fluid lower salinity fluids exsolved at near critical conditions and were trapped by inclusions that homogenize to liquid to vapor or by critical behavior the lack of cogenetic liquid and vapor rich fluid inclusions and phase equilibria constraints indicate that high salinity fluids or 57 wt nacl equiv were generated directly by the crystallizing magma and were not a product of aqueous fluid immiscibility

volcanic perturbation of the atmosphere in both polar regions 1991 1994 long term measurements by sunphotometers of the spectral dependence of aerosol optical depth are reported for several sites in the arctic and antarctic for the period january 1991 through december 1994 in the antarctic a pronounced increase of atmospheric turbidity was observed at the end of september 1991 the observed wavelength dependence in aerosol optical depth indicated that the increase was due to the presence of fresh and therefore small stratospheric aerosol particles associated with the eruption of cerro hudson in august 1991 after the breakdown of the polar vortex in mid november 1991 we measured a second significant increase of the aerosol optical depth at this time the 1 0 m aerosol optical depth was approximately 0 12 or about 10 times background levels this second incrcase is shown to be the result of the influx of mount pinatubo aerosols a similar perturbation of the aerosol optical depth was observed in the arctic with the return of sunlight in march 1992 however the increased loading of the arctic stratosphere by the pinatubo aerosols was already evident at high northern latitudes in satellite measurements at the end of 1991 stratospheric aerosol and gas experiment ii stratospheric 1 0 m optical depth measurements show that meridional transport of pinatubo aerosol from equatorial to middle and higher latitudes is greatest in the winter spring hemisphere this observation explains the observed seasonal trend of aerosol optical depth during the posteruption a significant decrease of the perturbation by mount pinatubo aerosol was observed in both polar regions by the end of 1994 the measured 1 0 m aerosol optical depths at this time were only 0 04 these values exceed the background level by about 0 01 0 02 therefore the aerosol optical depth values are still slightly higher than during undisturbed conditions in addition we show that the occurrence of volcanic aerosols caused changes in the spectral dependence of the aerosol optical depth in the arctic and the antarctic these variations including the changes in the aerosol size distribution derived from the aerosol optical depth are discussed in comparison to undisturbed conditions

seasonal and spatial variations in the chemistry of a high arctic supraglacial snow cover this paper describes the physical and chemical properties of the snowpack on john evans glacier ellesmere island canadian arctic archipelago and investigates the controls on snowpack solute concentrations and atmospheric deposition the snowpack contains three layers that are traceable across the whole glacier these represent fall accumulation that has been metamorphosed to depth hoar winter accumulation mixed with snow reworked by wind from the underlying depth hoar and spring accumulation mixed with wind reworked snow the seasonal cycle in snow chemistry closely reflects changes in the composition of the atmospheric aerosol at alert with some modification of no 3 concentrations by post depositional processes mean water weighted solute concentrations in the snowpack are largely independent of accumulation while atmospheric deposition tends to increase with accumulation this suggests that for most species wet deposition is the dominant depositional process throughout the year however concentrations of ca 2 and k increase with both accumulation and elevation implying an enhanced input from dry deposition of soil dust above 800 m elevation concentrations of so 4 2 are inversely related to accumulation especially in the winter layer suggesting a significant input from non precipitating events such as dry deposition or riming during this period of very limited snowfall

first sulfur isotope measurements in central greenland ice cores along the preindustrial and industrial periods 1 sulfur isotopes of sulfate have been measured in a discontinuous set of polar ice core samples from summit central greenland covering the preindustrial from the fourteenth to the eighteenth century and industrial from 1872 to 1969 a d periods results have been used to estimate the different source contributions to the deposited sulfate and their evolution along the last centuries they indicate that the preindustrial background sulfate budget is slightly dominated on a year round average by marine biogenic emissions amounting to close to half of the non sea salt sulfate 49 the second contribution is provided by continental sources of secondary sulfate including background volcanism and to a lesser extent continental biota 44 of the non sea salt sulfate sulfur emitted by relatively weak eruptions is found to be largely depleted in 34s compared to bulk volcanic s suggesting an efficient washout of the heavier isotope during the tropospheric transport the impact of human driven emissions on the sulfate deposited in central greenland ice is visible in isotope data as early as 1870 a d the isotopic signature of anthropogenic sulfur deposited during the twentieth century is found to be constant 34s 3 0 1 5 regardless of the changes of dominant source regions and emission processes this signature is slightly but measurably lighter than the one reported for arctic haze pollution events

inversion for seismic anisotropy using genetic algorithms1 a general inversion scheme based on a genetic algorithm is developed to invert seismic observations for anisotropic parameters the technique is applied to the inversion of shear wave observations from two azimuthal vsp data sets from the conoco test site in oklahoma horizontal polarizations and time delays are inverted for hexagonal and orthorhombic symmetries the model solutions are consistent with previous studies using trial and error matching of full waveform synthetics the shear wave splitting observations suggest the presence of a shear wave line singularity and are consistent with a dipping fracture system which is known to exist at the test site application of the inversion scheme prior to full waveform modelling demonstrates that a considerable saving in time is possible whilst retaining the same degree of accuracy

detection of multiple fracture sets using observations of shear wave splitting in microseismic data the hydrocarbon industry is moving increasingly towards tight sandstone and shale gas resources reservoirs that require fractures to be produced economically therefore techniques that can identify sets of aligned fractures are becoming more important fracture identification is also important in the areas of coal bed methane production carbon capture and storage ccs geothermal energy nuclear waste storage and mining in all these settings stress and pore pressure changes induced by engineering activity can generate or reactivate faults and fractures p and s waves are emitted by such microseismic events which can be recorded on downhole geophones the presence of aligned fracture sets generates seismic anisotropy which can be identified by measuring the splitting of the s waves emitted by microseismic events the raypaths of the s waves will have an arbitrary orientation controlled by the event and geophone locations meaning that the anisotropy system may only be partly illuminated by the available arrivals therefore to reliably interpret such splitting measurements it is necessary to construct models that compare splitting observations with modelled values allowing the best fitting rock physics parameters to be determined commonly splitting measurements are inverted for one fracture set and rock fabrics with a vertical axis of symmetry in this paper we address the challenge of identifying multiple aligned fracture sets using splitting measured on microseismic events we analyse data from the weyburn ccs eor reservoir which is known to have multiple fracture sets and from a hydraulic fracture stimulation where it is believed that only one set is present we make splitting measurements on microseismic data recorded on downhole geophone arrays our inversion technique successfully discriminates between the single and multiple fracture cases and in all cases accurately identifies the strikes of fracture sets previously imaged using independent methods borehole image logs core samples microseismic event locations we also generate a synthetic example to highlight the pitfalls that can be encountered if it is assumed that only one fracture set is present when splitting data are interpreted when in fact more than one fracture set is contributing to the anisotropy

isotopic composition of sulfur in size resolved marine aerosols above the atlantic ocean sulfur isotope measurements were performed on size segregated aerosols collected during the albatross oceanographic campaign from 61 n to 35 s above the atlantic ocean in october and november 1996 results obviously showed the dependence of the sulfur isotope ratio upon particle size the finest particles being depleted in 34s compared to coarse particles suggesting a heavier continental influence in the fine mode in the coarse mode 50 90 of the excess sulfate in both hemispheres was found to be of biogenic origin in the fine mode a different picture was obtained in the northern hemisphere the contribution of biogenic sulfur was found to be less than 35 of the excess sulfur even in relatively clean air masses on the other hand in the southern hemisphere the participation of biogenic sulfur was about 60 of the excess sulfur in purely marine air the contribution of continental sulfur to the fine fraction in the southern hemisphere was up to 40 25 even under pure oceanic conditions and far more in the northern hemisphere these results attest to the possible importance of long range transport of fine sulfate particles or so2 possibly through the free troposphere or the importance of anthropogenic emissions due to shipping

postsubduction porphyry cu au and epithermal au deposits products of remelting of subduction modified lithosphere porphyry cu mo au and some epithermal au deposits are formed from hydrothermal fluids exsolved from cooling water rich calc alkaline magmas emplaced in volcanoplutonic arcs above subduction zones these magmas originate by partial melting of the metasomatized asthenospheric mantle wedge however there is increasing evidence for the existence of a suite of porphyry cu au and epithermal au deposits related to magmas generated after subduction beneath the arc has ceased associated magmas tend to be mildly alkaline relatively sulfur poor and emplaced as isolated complexes rather than in voluminous volcanoplutonic arcs they are likely formed by remelting of previously subduction modified arc lithosphere triggered by postsubduction lithospheric thickening lithospheric extension or mantle lithosphere delamination metasomatized mantle lithosphere or hydrous lower crustal cumulates residual from first stage arc magmatism contain small amounts of chalcophile and siderophile element rich sulfides and constitute a fertile source for hydrous au rich but relatively sulfur poor magmas during later remelting the recognition that porphyry cu au and related epithermal au systems can also form in postsubduction and collisional tectonic settings expands the range of geological environments and geographical terranes that are prospective for such deposits

modelling the seismic attributes of overpressured siliciclastic rocks with a genetic annealing gan algorithm a genetic annealing gan algorithm is used to derive an empirical model which predicts compressional wave velocity values for overpressured siliciclastic rocks the algorithm involves non linear random searching and mutation techniques and its annealing component imposes a very strict control over the rate of convergence of the search this technique provides an alternative to the standard calculations involving the effective stress coefficient n the pore pressure is introduced into the model as an explicit variable and as part of an overpressure coefficient p p p c the ratio of pore to confining pressure empirical model derived data and known laboratory data are compared and their differences are shown to be within statistically acceptable error limits the empirical equation fits all under and overpressured data simultaneously irrespective of pore fluid pressure level with the same parameters it is used to predict seismic velocities very accurately for extreme levels of overpressure starting from normally pressured experimental data the model highlights the effect of pore pressure on the compressional wave velocity of fully saturated samples with different clay contents it can be used when the experimental data available are sparse and particularly when a prediction of material behaviour is necessary at specific pore fluid pressure and depth conditions

geology mineralization and fluid inclusion characteristics of the kumbel oxidized w cu mo skarn and au w stockwork deposit in kyrgyzstan tien shan the kumbel deposit is located within a metallogenic belt of w mo cu mo au w and au deposits along the late paleozoic active continental margin of tien shan the deposit is related to a late carboniferous multiphase pluton with successive intrusive phases from early olivine monzogabbro through monzonite quartz monzonite to granodiorite and granite with the latest monzogabbro porphyry dikes the deposit represents an example of a complex w cu mo au magmatic hydrothermal system related to magnetite series high k calc alkaline to shoshonitic igneous suite it contains large bodies of w cu mo oxidized prograde and retrograde skarns with abundant andradite garnet magnetite and especially hematite as well as k feldspar molybdoscheelite chalcopyrite and molybdenite with transitions to zones of intense quartz k feldspar with minor andradite and hematite veining the skarns are cut by quartz carbonate adularia sericite veins locally sheeted and stockworks bearing scheelite and minor cu zn pb sulfides as well as au bi te and as mineralization the association of these veins with the oxidized skarns and magnetite series intrusion is consistent with the general oxidized intrusion related w mo cu au type of deposit with an affinity to the alkalic silica saturated cu au mo porphyry deposits the fluid inclusion data show the predominance of magmatic hydrothermal aqueous chloride fluid during the formation of skarns and quartz carbonate scheelite sulfide veins the high fluid pressures 1 750 bars together with their high temperature up to 600 c and high salinity 50 60 wt nacl equiv suggest the formation of skarns and quartz k feldspar andradite hematite veins under conditions typical of magmatic hydrothermal transition depth of 4 5 km of intrusion related mineralized system possibly by exsolution of the fluids from crystallizing magma the auriferous quartz carbonate scheelite sulfide veins formed from high to moderate salinity from 40 to 20 wt nacl equiv and high pressure from 1 200 bars to 850 900 bars aqueous chloride fluids under decreasing temperature from 370 to 120 c the massive deposition of molybdoscheelite in retrograde skarn and scheelite in quartz carbonate scheelite sulfide veins could correspond to enrichment of fluids in ca up to 18 25 wt cacl2 likely from crystallizing magma

sources of aerosol sulphate at alert apportionment using stable isotopes from july 1993 to september 1994 seasonal variations in the sources of so42 aerosols in the arctic lower atmosphere at alert canada 82 30 n 62 20 w were investigated using the sulphur isotope abundance of as little as 10 g of sulphur analyzed by combustion flow isotope ratio mass spectrometry in conjunction with air mass trajectories and in parallel with measurements of aerosol composition the sulphur isotope composition was used to discern sources of aerosol so42 total so42 is composed of sea salt so42 marine biogenic and nonmarine so42 from june through september the fraction of biogenic so42 in the non sea salt nss component ranged from 0 09 to 0 40 with an average of 0 31 0 11 summertime nonmarine so42 is likely anthropogenic in origin since it is isotopically indistinguishable from so42 in the polluted winter spring period of arctic haze 34s 5 in summer there was no significant difference in isotope composition of aerosol sulphate between air which recently traversed eurasia and the arctic ocean and air arriving from north america in contrast to summer and late winter spring 34s values for nonmarine so42 in fall and early winter were often less than 5 these isotopically light samples were divisible into two groups 1 those associated with air mass trajectories potentially affected by north american soils and or smelters and 2 three weekly samples between october and december which could be attributed to fractionated sea salt aerosol formed on refrozen arctic ocean leads for the latter the ratio of so42 na was estimated to be a factor of 3 6 lower than in bulk seawater from november to may nonmarine aerosol so42 was apportioned into 10 aerosol components using positive matrix factor analysis of 18 aerosol ions and trace elements sirois and barrie this issue in turn a multiple linear regression of 34s values against the scores of the components was used to predict the isotope composition of six components it was concluded that the main mass of anthropogenic so42 had a 34s value near 5 and that biogenic so42 had a 34s of 16 3 9 reasonable agreement between model results and sulphur isotope measurements at alert show that so42 apportionment using positive matrix factor analysis is a reasonable approach which gives realistic results

the effect of the aspect ratio on crack induced anisotropy1 media containing aligned cracks show anisotropy with respect to elastic wave propagation there are several models describing the wave propagation in cracked media most of them only valid for cracks with small aspect ratios one of these models crampin s model is compared with a model valid for all aspect ratios nishizawa s model the elastic constants and the group velocities are compared for both dry and liquid filled inclusions with aspect ratios ranging from 0 0001 flat cracks up to 1 spheres the difference between both models is small for small aspect ratios but becomes larger for increasing aspect ratios at a crack density of 0 05 both models give within an error of 5 the same results for aspect ratios up to 0 3 therefore crampin s model can be applied to a large range of cracked media even if the aspect ratio of the inclusions is not small the variation of the anisotropy as a function of the aspect ratio can be studied using thomsen s dimensionless parameters e and y they show how inclusions with large aspect ratios result in elliptical anisotropy