dynamical and microphysical characteristics of arctic clouds during base abstract in this study observations from aircraft doppler radar and landsat are used to better understand dynamical and microphysical characteristics of low level arctic clouds for climate change studies observations during the beaufort and arctic storms experiment were collected over the southern beaufort sea and the northern mackenzie river basin during 1 september 14 october 1994 measurements from the cases of 8 september and 24 25 september are analyzed in situ observations were made by instruments mounted on a convair 580 research aircraft reflectivity and radial winds were obtained from an x band doppler radar located near inuvik the reflectivity field from landsat observations concurrent with the aircraft and radar observations was also obtained dynamical activity representing vertical air velocity wa and turbulent fluxes is found to be larger in cloud regions the sizes of coherent structures e g cells are from 0 1 to 15 km as determined by wavelet analysis and time series of airc

migration paths and precipitation mechanisms of ore forming fluids at the shuiyindong carlin type gold deposit guizhou china abstract shuiyindong is one of the largest and highest grade stratabound carlin type gold deposits in china this paper reports on the results of petrographic studies electron microprobe analyses empa of arsenian pyrite and the mass transfer during mineralization and alteration and it presents the deposit scale distributions of au as sb hg tl and trace elements in a representative cross section across the shuiyindong carlin type gold deposit guizhou province the main objectives were to identify the precipitation mechanisms of minerals or elements from fluids and the migration paths of ore forming fluids petrographic and empa studies indicate that gold in the primary ores is mainly hosted by arsenian pyrite mass transfer associated with alteration and mineralization shows that au as sb hg tl and s were significantly added to all mineralized rocks fe 2 o 3 and sio 2 were immobile in the main orebodies that are hosted in bioclastic limestone and cao na 2 o sr and li were removed from country rocks the relations between fe and s indicate that the sedimentary rocks at the shuiyindong deposit contain more iron than is needed to combine with all of their contained sulfur to form pyrite this suggests that sulfidation and decarbonation were the principal mechanism of gold precipitation at the shuiyindong deposit hg sb and as commonly formed sulfide minerals such as stibnite realgar and orpiment in late stage quartz calcite veins or absorbed by organic matter in argillite fluid cooling presumably led to depositions of stibnite realgar and orpiment in late stage quartz calcite veins organic matter likely served as a reductant in argillite for the ore fluids causing the precipitation of as sb hg and s as well as au deposit scale distributions of gold and other relevant elements reflect the passage of fluids through the rocks rock strata and structures allowed the ore forming fluids to migrate horizontally along the unconformity surface of the middle upper permian converge on the high position of an anticline and then ascend into the overlying strata along the anticlinal axis the distributions of the major and trace elements show that elements that accompanied the ore forming fluids include au as sb hg tl and s and that na 2 o and li were exhausted in the longtan formation at the anticlinal core during gold mineralization the enrichment of co cr and ni in the longtan formation at the anticlinal core might be associated with deformation that formed the anticline or with gold mineralization different host rocks were preferentially mineralized by different elements the bioclastic limestone is commonly enriched in au whereas the argillite is preferentially enriched in as hg sb and tl the zonation of ore forming elements in the deposit appears to be sb tl as hg au hg as from bottom to top enrichment of au as sb hg and tl provides useful guidance for the exploration for carlin type gold deposits in guizhou anomalies of as and hg in soil or stream sediment might be an important clue and these elements can be used as indicator elements ore forming fluids migrated along the unconformity surface of the middle upper permian and the anticlinal axis so these are favorable sites for exploration for carlin type gold deposits in guizhou

cirrus mammatus properties derived from an extended remote sensing dataset abstract the first quantitative and statistical evaluation of cirrus mammatus clouds based on wavelet analysis of remote sensing data is made by analyzing the university of utah facility for atmospheric remote sensing fars 10 yr high cloud dataset first a case study of cirrus mammata combining a high resolution lidar system and a w band doppler radar is presented yielding an assessment of the thermodynamic environment and dynamic mechanisms then 25 cirrus mammatus cases selected from the fars lidar dataset are used to disclose their characteristic environmental conditions and vertical and length scales the results show that cirrus mammata occur in the transition zone from moist cloudy to dry air layers with weak wind shear which suggests that cloud induced thermal structures play a key role in their formation their maximum vertical and horizontal length scales vary from 0 3 to 1 1 km and 0 5 to 8 0 km respectively it is also found that small scale structures develop between the large scale

origin of late archean granite geochemical evidence from the vermilion granitic complex of northern minnesota the 2 700 ma vermilion granitic complex of northern minnesota is a granite migmatite terrane composed of supracrustal metasedimentary rocks mafic rocks tonalitic and granodioritic plutonic rocks and granite the metasedimentary rocks are predominantly graywacke which has been regionally metamorphosed to garnet sillimanite muscovite bearing biotite schist and has locally undergone anatexis the mafic rocks form early phases within the complex and are of two types 1 basaltic amphibolite and 2 monzodiorite and essexite rich in large ion lithophile elements lile the members of the early plutonic suite form small bodies that intrude the metasedimentary rocks and mafic rocks producing an early migmatite the granite is of two distinct varieties 1 white garnet muscovite biotite leucogranite s type chappell and white 1974 and 2 grayish pink biotite magnetite lac la croix granite i type the leucogranite occurs in the early migmatite and in paragneissic portions of the complex whereas the lac la croix granite is a late stage intrusive phase that invades the early migmatite and metasediment producing a late migmatite and forms a batholith this study focuses specifically on the origin of granite in the vermilion granitic complex chemical mass balance calculations suggest that the s type two mica leucogranite had a metagraywacke source and that the i type lac la croix granite formed via partial fusion of calc alkaline tonalitic material which may have been similar to rocks of the early plutonic suite this model is satisfactory for petrogenesis of similar late archean post kinematic granites throughout the canadian shield

genesis of the mandongshan gold deposit xinjiang nw china t p ƒs2 and phase equilibria constraints from the au as fe s system abstract the mandongshan gold deposit located in the west junggar xinjiang china is hosted in early carboniferous basalt and tuff ore bodies mainly consist of gold bearing hydrothermal veins mineralized basalt and tuff with disseminated sulfides hydrothermal process could be identified based on ore petrographic studies quartz albite sulfide native gold stage i arsenopyrite calcite native gold ii and pyrite calcite iii microthermometric and laser raman spectroscopic analysis of fluid inclusions in quartz demonstrate the ore forming fluid at stage i was moderate temperature 360 398 c low salinity 0 5 5 1 wt nacl equiv and h 2 o ch 4 dominant which evolved to low salinity 0 2 1 2 wt nacl equiv with insignificant content of ch 4 at 219 267 c stage iii contents of ore elements as au cu sb ba cs rb in mineralized basalt are higher than those in fresh basalt phase analysis for the au as fe s system using supcrt92 software package with the updated database of slop98 dat indicates that a decrease of h 2 s activity and oxygen fugacity caused by phase separation and fluid rock reactions induced native gold precipitation at stage i the decrease of h 2 s activity triggered by arsenopyrite crystallization caused native gold deposition at stage ii

a review of te and se systematics in hydrothermal pyrite from precious metal deposits insights into ore forming processes abstract pyrite is one of the most common minerals in many precious and base metal hydrothermal ore deposits and is an important host to a range of trace elements including au and co and the semi metals as se sb te and bi as such in many hydrothermal ore deposits where pyrite is the dominant sulphide phase it can represent a major repository for these elements furthermore the concentrations and ratios of au as and co in pyrite have been used to infer key ore forming processes however the mechanisms controlling the distribution of te and se in pyrite are less well understood here we compare the te and se contents of pyrite from a global dataset of carlin type orogenic au and porphyry epithermal deposits to investigate 1 the potential of pyrite to be a major repository for these elements and 2 whether te and se provide insights into key ore forming processes pyrite from carlin type low sulphidation and alkaline igneous rock hosted epithermal systems is enriched in te and se compared to pyrite from high sulphidation epithermal and porphyry cu deposits orogenic au pyrite is characterised by intermediate te and se contents there is an upper solubility limit for te as a function of as in pyrite similar to that established for au by reich et al 2005 and this can be used to identify te present as telluride inclusions which are common in some epithermal porphyry and orogenic au deposits physicochemical fluid parameters such as ph redox and temperature as well as crystal chemistry control the incorporation and concentration of se and te in pyrite neutral to alkaline fluids have the ability to effectively mobilise and transport te fluid boiling in porphyry epithermal systems as well as wall rock sulphidation and oxidation in carlin type and orogenic au deposits can effectively precipitate te in association with pyrite and au in contrast se concentrations in pyrite apparently vary systematically in response to changes in fluid temperature irrespective of ph and f o 2 hence we propose that the se contents of pyrite may be used as a new geo thermometer for hydrothermal ore deposits furthermore the comparison of bulk ore and pyrite chemistry indicates that pyrite represents the major host for te and se in carlin type and some epithermal systems and thus pyrite can be considered to be of economic interest as a potential source for these elements

textural control on gold distribution in as free pyrite from the dongping huangtuliang and hougou gold deposits north china craton hebei province china article i nfo pyrite from the dongping huangtuliang and hougou gold deposits hebei province china was investigated using a combination of ore microscopy including back scattered imaging and in situ laser ablation inductively coupled plasma mass spectroscopy la icp ms a range of elements including au te ag pb bi cu co ni and as was analyzed with the aim to constrain the textural controls and influence of superimposed deformation on the distribution of invisible gold in as free pyrite thedatasetshowsexcellentcorrespondence betweenmeasuredhighgoldvaluesandthreekeytexturalcriteria i areasofclusteredtellurideinclusions especiallyindongping ii microshearingandfracturing brecciation dongping and huangtuliang and iii pyrite recrystallization huangtuliang invisible gold is only at trace levels in the hougou and gold bearing telluride minerals are not observed this is considered to result from larger scale remobilization of gold during advanced brecciation and recrystallization of pyrite pyrite grains containing clustered inclusions have by far the highest gold concentrations up to 1 wt with consistent values of thousands of ppm au interpretation of textures and la icp ms data infers that in these areas the distribution of telluride inclusions extends pervasively from micron to nanoscale i e as fields of nanoparticles local employment of coupled dissolution reprecipitation reaction between pyrite and fluids driving the k metasomatic alteration dated at 150 ma is invoked to explain such patterns syn deformational grain scale mobilization of gold and other elements took place leading to a portion of the gold being recrystallized within fractures and microshears the deformational event leads to gold enrichment in the huangtuliang pyrite where brittle fracturing brecciation has been followed by a resorption and recrystallization in the latter case foam textured pyrites again without as can contain up to hundreds of ppm gold theinterpreted sequenceof pyritepost depositional eventsis inaccordancewith the protracted magmaticevolution of the area starting with variscan alkaline intrusions 390 ma and reactivated during the yanshanian orogeny 150 ma thestudyshows i thatas freepyritecanreadilycontainsignificantamountsofinvisiblegold bothasnanoparticles

geochemistry and textures of gold bearing arsenian pyrite twin creeks nevada implications for deposition of gold in carlin type deposits this study relates morphology size texture and chemistry of arsenian pyrite in the twin creeks carlin type gold deposits to the chemical position and amount of gold that it contains arsenian pyrite is confirmed as the most important gold hosting mineral and four types of gold bearing arsenian pyrite are recognized among these four types the lowest amount of gold and arsenic 1 wt as 17 60 ppm au is contained in arsenian pyrite with relatively large grain sizes 10 30 mu m it formed at relatively high temperatures 250 degrees c and k super h super ratios adularia stable probably relatively slowly the largest amount of gold and arsenic 1 05 2 43 wt as 595 1 465 ppm au is contained in arsenian pyrite with small grain sizes up to 2 mu m that formed at low temperatures 120 degrees 200 degrees c and moderate k super h super ratios illite stable probably by relatively rapid deposition xanes exafs and sims analyses show that gold in arsenian pyrite is both structurally bound au i and in submicroscopic inclusions of free gold au highest amounts of structurally bound gold were observed in the relatively coarse grained arsenian pyrite noted above whereas most inclusions of free gold were observed in fine grained arsenian pyrite in general there is a good correlation between gold and arsenic in arsenian pyrite although au as ratios vary from one pyrite to another it is suggested that gold in arsenian pyrite was deposited by direct deposition of native gold and by adsorption of au i from hydrothermal solutions adsorption of gold by arsenian pyrite can take place from solutions that are not saturated with respect to native gold relative volumes of gold bearing pyrite from different paragenetic stages at twin creeks suggest that as much as 50 percent of the total gold in the deposit could have formed from solutions that were not saturated with respect to native gold because both au and au i are found together in arsenian pyrite it is likely that they were deposited by the same process consideration of possible depositional reactions suggests that a decrease in the activity of reduced sulfur is most likely to cause gold deposition

mesoscale spectral analysis of in situ horizontal and vertical wind measurements at 6 km as part of the aloha anlc 93 campaign to investigate atmospheric dynamics in situ wind measurements collected at 6 km with the gust probe sensor attached to the national center for atmospheric research electra aircraft were analyzed for 16 flight segments between 61 n and 14 s and between 92 w and 170 w over land and water horizontal wavenumber spectra for the vertical wind and both zonal and meridional horizontal wind components were calculated the zonal and meridional wavenumber spectra exhibited a decrease in the spectral slope from 1 98 0 02 for wavelengths between 2 km and 100 km to 3 18 0 06 for the longer wavelengths between 100 km and 330 km the wavenumber spectrum for the vertical wind component showed a 2 power law dependence for wavelengths in excess of 5 km and a generally flat shape at shorter wavelengths an increase in power at the wavelength of 10 km was detected for the meridional wavenumber spectrum these results were compared with predictions from two spectral models and with spectral results from other observations

spectral analysis of quikscat surface winds and two dimensional turbulence a spectral decomposition of quikscat surface wind vectors reveals different levels of variance and different values of the spectral slope in various regions of the world ocean for the 12 months investigated the traditional considerations on the factors affecting the shape of the spectra are reviewed and compared to the results in particular the influence of large scale synoptic systems is shown by comparing the steeper and more energetic spectra of the midlatitudes to the shallower spectra of the tropics similarly the signature of convection is investigated by comparing spectra in the tropical convectively active and dry zones of the pacific ocean spectra of vorticity and divergence are calculated along with spectral vorticity to divergence ratios their spatial and temporal variations are discussed it is hypothesized that when convection is enhanced in the tropics the spectral analysis captures the mesoscale synoptic structures in which convection is embedded and that the spectra exhibit some of the characteristics of their midlatitude counterparts i e steeper and more energetic

building archean cratons from hadean mafic crust geologic processing of earth s surface has removed most of the evidence concerning the nature of earth s first crust one region of ancient crust is the hudson bay terrane of northeastern canada which is mainly composed of neoarchean felsic crust and forms the nucleus of the northeastern superior province new data show these 2 7 billion year old rocks to be the youngest to yield variability in neodymium 142 142nd the decay product of short lived samarium 146 146sm combined 146 147sm 142 143nd data reveal that this large block of archean crust formed by reworking of much older 4 2 billion year old mafic crust over a 1 5 billion year interval of early earth history thus unlike on modern earth mafic crust apparently could survive for more than 1 billion years to form an important source rock for archean crustal genesis

missing eu anomaly and archean high grade granites granites emplaced in low grade granite greenstone archean terranes typically exhibit negative eu anomalies and such eu anomalies have been transmitted to post archean cratonic sediments by weathering and erosion because average continental crust does not exhibit an eu anomaly a complementary reservoir with a positive eu anomaly must exist to balance the low grade granites neither the upper mantle nor average archean lower crust appears to represent this reservoir archean lower crustal rocks which are dominantly plutonic rocks of tonalitic composition have ree distributions indicative of a mafic parentage however archean high grade granites in southern india exhibit the required positive eu anomalies and may be representative of a widespread positive eu anomaly reservoir in the lower crust geochemical model studies indicate that archean low and high grade granites may represent residual liquid and cumulate respectively from the fractional crystallization of a granite parent magma produced by partial melting of tonalitic rocks in the lower crust such melting may occur at the wave front of a co 2 rich fluid that dehydrates the lower crust and produces granulites

the horizontal kinetic energy spectrum and spectral budget simulated by a high resolution troposphere stratosphere mesosphere gcm abstract horizontal kinetic energy spectra simulated by high resolution versions of the geophysical fluid dynamics laboratory skyhi middle atmosphere general circulation model are examined the model versions considered resolve heights between the ground and 80 km and the horizontal grid spacing of the highest resolution version is about 35 km tropospheric kinetic energy spectra show the familiar 3 power law dependence on horizontal wavenumber for wavelengths between about 5000 and 500 km and have a slope of 5 3 at smaller wavelengths qualitatively similar behavior is seen in the stratosphere and mesosphere but the wavelength marking the transition to the shallow regime increases with height taking a value of 2000 km in the stratosphere and 4000 km in the mesosphere the global spectral kinetic energy budget for various height ranges is computed as a function of total horizontal wavenumber contributions to the kinetic energy tendency from nonlinear advective processes from conversion of avai

first observations of turbulence parameters in the troposphere over the bay of bengal and the arabian sea using radiosonde 1 this paper discusses the turbulence characteristics of the free atmosphere over the bay of bengal and the arabian sea during the premonsoon season of 2006 the turbulence scaling concepts developed over the past decades for application to oceanic mixing are used for retrieving turbulence properties in the free atmosphere from high resolution soundings as described by clayson and kantha 2008 the variability in the vertical turbulence structure over a large spatial region is studied using this novel method for the first time investigations revealed the presence of a highly turbulent band at upper troposphere below the cold point tropopause cpt with significant enhancements in thorpe length and eddy diffusion coefficient this increased turbulence is studied in conjunction with the observations of the tropical tropopause layer ttl it is seen that the lower and upper boundaries of this turbulence band nearly coincide with the height where the potential temperature lapse rate begins to show a decrease lrhmin and cold point tropopause respectively the ttl is the transition regime from convectively dominated troposphere to radiatively dominated stratosphere and is characterized by a decrease in the static stability the enhanced zonal and meridional wind shear observed in this region shows that the stability in this region is further weakened because of the breaking of kelvin helmholtz waves which results in the enhancement of turbulence the study reveals the potential of high resolution soundings to be used in the investigations of turbulence in the free atmosphere

airborne observations of turbulence mixing and gravity waves in the tropopause region 1 in situ observations of small scale dynamics and compositional structure in the tropopause region are presented the measurements were made aboard the grob egrett high altitude research aircraft above aberystwyth wales in the summer of 2000 the observations presented here show evidence of mixing of ozone and water vapor in a patch of intense turbulence just above the tropopause this turbulence is shown to be the result of wind shear above a tropospheric jet stream the value of the vertical eddy diffusion coefficient in this turbulence is estimated to be 0 9 m2 s 1 it is also shown that wavelike perturbations superimposed on the overall tracer structure can be accounted for by a gravity wave

mesoscale dynamical regimes in the midlatitudes the atmospheric mesoscales are characterized by a complex variety of meteorological phenomena that defy simple classification here a full space time spectral analysis is carried out based on a 7 day convection permitting simulation of springtime midlatitude weather on a large domain the kinetic energy is largest at synoptic scales and on the mesoscale it is largely confined to an advective band where space and time scales are related by a constant of proportionality which corresponds to a velocity scale of about 10 m s 1 computing the relative magnitude of different terms in the governing equations allows the identification of five dynamical regimes these are tentatively identified as quasi geostrophic flow propagating gravity waves stationary gravity waves related to orography acoustic modes and a weak temperature gradient regime where vertical motions are forced by diabatic heating

airborne measurements of gravity wave breaking at the tropopause 1 a breaking atmospheric gravity wave was investigated with a combination of airborne in situ dynamical measurements and ground based vhf radar observations the wave was generated by flow over mountains and it was observed to break near the tropopause the measurements reveal that the wave was overturning at the tropopause and that the initial breakdown into turbulence involved the generation of smaller oscillations with a horizontal wavelength of around 500 m there was also evidence that the turbulence associated with the wave breaking can cause substantial mixing in the tropopause region

small scale motions observed by aircraft in the tropical lower stratosphere evidence for mixing and its relationship to large scale flows abstract measurments of temperature and ozone from instrumental aircraft in the tropical lower stratosphere show the presence of small scale disturbances generated by 1 underlying cumulus convection and 2 kelvin helmholtz instability the disturbances associated with underlying convection have peak to peak vertical parcel excursions of 300 m flying conditions were smooth suggesting an ensemble of gravity waves and little or no turbulent mixing it is nevertheless possible that these waves break at other altitudes leading to turbulent mixing and net fluxes of vertically stratified tracers disturbances attributed to kh instability implied vertical parcel excursions of 300 400 m the disturbances coincided with rough flying conditions suggesting turbulent mixing a linear stability analysis of the atmospheric basic state defined by high resolution radiosondes shows fastest growing waves with horizontal wavelengths of 1 4 1 8 km consistent with the aircraft observations the strong shears responsible

hydrothermal characterization of the west gore sb au deposit meguma terrane nova scotia canada the west gore sb au deposit is anomalous in the megurea terrane of nova scotia because of its enrichment in sb a metal that is essentially absent from other megurea gold deposits the deposit is hosted by graphitic and sulfide bearing slates of the lower paleozoic halifax formation that were deformed into a northeast trending upright closed syncline and metamorphosed to the greenschist facies during the regional acadian orogeny ca 400 ma mineralized veins at the deposit define a single structure trending 110 degrees that probably formed the dextral component of a conjugate shear system as part of regional northwest directed compression the veins crosscut a penetrative regional schistosity s 1 in the host slates and vein formation is constrained by 1 the presence of cleaved wall rock slates in the veins 2 vein related sulfides overgrowing the s 1 fabric in wall rock fragments and 3 a 370 ma 40 ar 39 ar plateau age for hydrothermal muscovite mineralization occurs as stibnite native antimony aurostibnite au sb alloys and au sb o phases in vein quartz with associated fe as pb zn cu sulfides and chlorite carbonate gangue wall rock alteration is variably developed as narrmv zones peripheral to veins enriched in sericite calcite sulfides tourmaline and chlorite early stages of mineralization are constrained to maximum temperatures of 495 degrees c from arsenopyrite geothermometry but lower temperatures are recorded by chlorite geothermometry 350 degrees 390 degrees c textures of vein quartz include comb and plumose varieties with a bimodal grain size and also a coarser anhedral quartz fluid inclusion studies indicate that the fluid was a mixed h 2 o nacl cacl 2 co 2 ch 4 type and that fluid unmixing occurred albeit in minor amounts thermometric measurements reveal maximum t h of 375 degrees c and a range of salinities 0 4 28 1 wt nacl equiv the volumetric properties of fluid inclusions reflect cycling of fluid pressures with supralithostatic pressures to 4 5 kbars p fluid recorded by the presence of h 2 o co 2 inclusions to 20 mole co 2 which are interpreted to have resulted from fluid rock interaction subsequent reduction in fluid pressures to ca 2 kbars resulted in decreasing amounts of co 2 1 2 mole and fluid unmixing that generated higher and lower salinity trends observed in t h salinity plots vein forming fluids are characterized by delta 13 c sub sigma c 19 5 to 22 6 per mil delta 18 o sub h 2 o 9 to 15 per mil delta d 42 to 64 per mil and delta 34 s sub h 2 s 9 7 to 10 3 per mil based on analysis of calcite quartz fluid inclusion extracts in quartz and stibnite vein tourmaline associated with stibnite has 87 sr 86 sr measured of 0 71707 to 0 72284 these data are consistent with a metamorphic origin for the fluid with local inheritance of c and s isotope signatures from interaction of the ore fluid with graphite and sulfide wall rock slates of the halifax formation the west gore deposit originated from infiltration of metamorphic derived fluids generated during the waning stages of the acadian orogeny contemporaneous with generation and emplacement of felsic and mafic magmas the mineralizing fluids were focused to higher crustal levels p fluid ca 2 kbars where brittle ductile conditions prevailed and veins were localized to the dextral component of a conjugate shear system related to movement along a major dextral strike slip fault or shear zone cobequid chedabucto fault system deposition of vein constituents resulted from a decrease in temperature and changes in fluid chemistry decrease in f sub s 2 and f sub o 2 induced by fluid unmixing and interaction with the wall rock lithogeochemistry of the local stratigraphy does not indicate any regional enrichment in sb au or other metals the occurrence of the stibnite may therefore reflect either telescoping of metals in a au w sb province or enrichment of sb in the source area or fluid conduit relative to other meguma gold deposits

velocity and temperature structure functions in the upper troposphere and lower stratosphere from high resolution aircraft measurements abstract high resolution measurements obtained from noaa best atmospheric turbulence bat probes mounted on an egrett high altitude research aircraft were used to characterize turbulence in the upper troposphere and lower stratosphere at scales from 2 m to 20 km focusing on three dimensional behavior in the sub kilometer scale range data were analyzed for 129 separate level flight segments representing 41 h of flight time and 12 600 km of wind relative flight distances the majority of flights occurred near the tropopause layer of the winter subtropical jet stream in the southern hemisphere second order structure functions for velocity and temperature were analyzed for the separate level flight segments individually and in various ensembles a 3d scaling range was observed at scales less than about 100 m with power law exponents for the structure functions of the velocity component in the flight direction varying mostly between 0 4 and 0 75 for the separate flight segments but close to for the

stratospheric gravity wave fluxes and scales during deepwave abstractduring the deep propagating gravity wave experiment deepwave project in june and july 2014 the gulfstream v research aircraft flew 97 legs over the southern alps of new zealand and 150 legs over the tasman sea and southern ocean mostly in the low stratosphere at 12 1 km altitude improved instrument calibration redundant sensors longer flight legs energy flux estimation and scale analysis revealed several new gravity wave properties over the sea flight level wave fluxes mostly fell below the detection threshold over terrain disturbances had characteristic mountain wave attributes of positive vertical energy flux efz negative zonal momentum flux and upwind horizontal energy flux in some cases the fluxes changed rapidly within an 8 h flight even though environmental conditions were nearly unchanged the largest observed zonal momentum and vertical energy fluxes were mfx 550 mpa and efz 22 w m 2 respectively a wide variety of disturbance scales were found at flight level over

magmatic oxidation state of the baogutu porphyry copper deposit in the west junggar of china implication for ore formation abstract the ore forming processes in the baogutu porphyry copper deposit are spatially and temporally related to the late carboniferous intrusions in the west junggar of china the mineralized intrusions consisting of granodiorite quartz diorite and diorite are characterized by moderate zircon ce4 ce3 ratios 15 9 163 and eu eu ratios 0 25 0 57 eu eu eun smn gdn 1 2 estimated magmatic oxidation state based on amphibole crystallized in the deep magma chamber logfo2 fmq 1 7 is lower comparing with that based on amphibole crystallized in the shallow magma chamber logfo2 fmq 3 5 the baogutu ore forming magmas were moderately oxidized with an average logfo2 value of fmq 2 5 based on amphibole oxygen barometer or fmq 2 7 based on magnetite ilmenite oxygen barometer these data indicate that the baogutu ore forming magmas were moderately oxidized

native antimony in the baogutu gold deposit west junggar nw china its occurrence and origin abstract the baogutu gold deposit west junggar xinjiang nw china is composed of quartz sulfide veins and their stockworks and is hosted within an early carboniferous volcanic sedimentary sequence three ore forming paragenetic stages can be identified coarse grained quartz sulfide vein stage i gold bearing fine grained quartz sulfide vein stage ii and native antimony bearing calcite sulfide veinlets stage iii the estimated formation temperatures approximately 360 to 220 c f s 2 7 to 15 log units and f o 2 26 to 43 log units decrease from stage i through stage ii to stage iii the nature of the hydrothermal fluid changed from weakly acidic ph 5 to 6 at stage i to alkaline ph 7 at stage iii two different occurrences of native antimony could be identified one coexists with chalcopyrite and pyrrhotite whereas the other occurs as isolate grains within calcite veins native antimony up to 100 m in size contains minor amounts of as 2 0 to 2 7 wt empirical formula sb 0 95 0 96 as 0 03 0 04 decrease of temperature and f o 2 at high ph and low f s 2 conditions favored co precipitation of native antimony ullmannite assemblages and the decomposition of tetrahedrite native antimony crystallized later than the native gold suggesting fractionation between au and sb during the hydrothermal evolution of the deposit

paleozoic crustal growth and metallogeny of central asia evidence from magmatic hydrothermal ore systems of central kazakhstan abstract the ore deposit spectrum of central kazakhstan reflects a range of lithospheric magmatism controlled by the polycyclic geodynamic evolution of an active continental margin which develops from back arc oceanic settings volcanic hosted massive sulphide cu au ore deposits to subduction controlled calcalkaline magmatism copper porphyries with subsequent stages of crust differentiation of low degree partial melting and extended intramagmatic fractionation molybdenum porphyries on to continental rifting peralkaline ree zr nb rich systems mesothermal gold deposits mark transcrustal shear zone controlled fluid conduits formed during arc slicing and thermal relaxation in a post orogenic setting the ore deposits characterize successive and spatially overlapping stages of crustal growth and consolidation the general subduction setting of this range of ore deposits is reflected by calc alkaline trends in the associated subalkaline high k felsic rocks with a wide range in silica contents the predominant metal spectrum of au cu and mo indicates relatively oxidized magmatic hydrothermal systems in accordance with the metaluminous i type nature of their igneous host rocks i e oxidized igneous precursor material despite of presumably highly variable ratios of mantle crust components in individual magmatic systems gabbros to leucogranites most rocks have very similar positive initial e nd values of 0 to 5 5 and depleted mantle model ages in the range of 500 800 ma the ubiquitous relatively young mantle extraction age is likely to characterize the lower crust of central kazakhstan this basement is interpreted as back arc oceanic crust that formed behind oceanwards drifting continental margin slivers during the initial stages of the active continental margin evolution of the late precambrian angara baltica supercontinent the early back arc oceanic crust was transformed into the present lower crust during the paleozoic orogenic evolution in which the back arc crust was buried by magmatic arc and sedimentary material and recurrently affected by high grade metamorphism basaltic melt injection underplating and granitic melt extraction anorogenic rift related permian peralkaline riebeckite granites with ree zr nb mineralization have very high positive e nd of 5 to 8 which is probably inherited from young subcrustal lithosphere at the mantle crust boundary that was affected by partial remelting due to asthenospheric upwelling during rifting

influences of gravity waves on convectively induced turbulence cit a review thunderstorms are known to produce turbulence such turbulence is commonly referred to as convectively induced turbulence or cit and can be hazardous to aviation although this turbulence can occur both within and outside the convection out of cloud cit is particularly hazardous since it occurs in clear air and cannot be seen by eye or onboard radar furthermore due to its small scale and its ties to the underlying convection it is very difficult to forecast guidelines for out of cloud cit avoidance are available but they are oversimplified and can be misleading in the search for more appropriate and physically based avoidance guidelines considerable research has been conducted in recent years on the nature of the phenomenon and in particular its connection to gravity waves generated by the convection this paper reviews the advances in our understanding of out of cloud cit and its relation to convective gravity waves and provides several detailed examples of observed cases to elucidate some of the underlying dynamics

geology fluid inclusions and geochemistry of the zhazixi sb w deposit hunan south china abstract the zhazixi sb w deposit in the xuefeng uplift south china exhibits a unique metal association of w and sb where the w orebodies are hosted by interlayer fractures and the sb orebodies are contained within nw trending faults this study proposes that the w and sb mineralization took place in two separate periods the mineral paragenesis of the w mineralization reveals a mass of quartz scheelite and minor calcite the mineral assemblage of the sb mineralization developed after w mineralization and consists of predominantly quartz and stibnite and small amounts of native sb berthierite chalcostibnite pyrite and chalcopyrite fluid inclusions in quartz and coexisting scheelite are dominated by two phase liquid rich aqueous inclusions at room temperature microthermometric studies suggest that ore forming fluids for w mineralization are characterized by moderate temperatures 170 270 c low salinity 3 7 wt nacl equiv low density 0 75 0 95 g cm 3 and moderate to high pressure 57 2 99 7 mpa and these fluids experienced a cooling and dilution evolution during w mineralization ore forming fluids for sb mineralization are epithermal types with low temperatures 150 230 c low salinity 4 6 wt nacl equiv moderate density 0 82 0 94 g cm 3 and high pressure 42 2 122 5 mpa and these fluids display an evident decline in homogenization temperature during sb mineralization laser raman analyses of the vapor phase indicate that the ore forming fluids for both w and sb mineralization contain a small amount of co 2 the ore forming fluids for sb mineralization are identified as predominantly originating from the continental crust as suggested by the low 3 he values 0 009 10 12 cc stp g and 3 he 4 he ratios 0 002 0 056 ra as well as high 36 ar values 1 93 10 9 cc stp g and 40 ar 36 ar ratios 909 5 2279 7 the source of s is identified to be the neoproterozoic wuqiangxi formation as traced by the 34 s v cdt values of stibnite 3 1 9 4 the 208 pb 204 pb 37 643 40 222 207 pb 204 pb 15 456 15 681 and 206 pb 204 pb 17 093 20 042 ratios suggest a mixture of lower crustal and supracrustal pb sources it is thus concluded that the ore genesis of the zhazixi sb w deposit is related to the intracontinental orogeny during the early mesozoic fluid mixing is considered to be the critical mechanism involved in w mineralization whereas a fluid cooling process is responsible for sb mineralization furthermore the absence of au is attributed to the low a s content in sb mineralizing fluids

climatology of high cloud dynamics using profiling arm doppler radar observations abstractice cloud properties are influenced by cloud scale vertical air motion dynamical properties of ice clouds can be determined via doppler measurements from ground based profiling cloud radars here the decomposition of the doppler velocities into reflectivity weighted particle velocity vt and vertical air motion w is described the methodology is applied to high clouds observations from 35 ghz profiling millimeter wavelength radars at the atmospheric radiation measurement program arm southern great plains sgp climate research facility in oklahoma january 1997 december 2010 and the arm tropical western pacific twp site in manus july 1999 december 2010 the doppler velocity measurements are used to detect gravity waves gw whose correlation with high cloud macrophysical properties is investigated cloud turbulence is studied in the absence and presence of gw high clouds are less turbulent when gw are observed probability density functions of vt w and high cloud macrophysical propert

episodic mantle melting crustal reworking in the late neoarchean of the northwestern north china craton zircon ages of magmatic and metamorphic rocks from the yinshan block abstract the yinshan block in the northwestern north china craton comprises late neoarchean greenstones high grade metamorphic rocks granulite charnockite enderbite and amphibole gneiss diorites sanukitoid and mg adakite and granitoids predominantly trondhjemite tonalite a greenstone terrane comprises a volcanic sequence of predominant basalt and dacite with minor andesite zircons from a high mg andesite and an andesite have weighted mean 207pb 206pb ages of 2533 5 ma and 2510 7 ma respectively which reflect the timing of two distinct volcanic episodes these two either predated or postdated a major volcanic episode that formed a basalt dacite bimodal suite during 2515 10 basalt to 2516 10 ma dacite magmatic zircons from the high grade metamorphic rocks yielded weighted mean 207pb 206pb ages of 2544 5 ma for a mafic granulite 2521 6 ma for a garnetiferous gneiss 2535 5 ma for a charnockite and 2526 5 ma for an amphibole gneiss these ages reflect the minimum emplacement time of rocks that make up the protoliths of the high grade metamorphic complex the metamorphic ages of the high grade complex were determined at 2515 18 ma for mafic granulite and 2503 12 ma for garnetiferous gneiss zircons from a high mg diorite i e sanukitoid have a weighted mean age of 2520 6 ma which is significantly younger than the 2556 14 ma age of a magnesian diorite mg adakite from the same diorite massif these ages reflect distinctive magmatic pulses that generated the diorite massif a tonalite has a zircon age of 2516 7 ma indistinguishable from the 2520 9 ma age of a trondhjemite from the same trondhjemite tonalite dominated batholith a granitic compositional layer in the 2516 7 ma tonalite has zircon ages of 2515 6 ma high u zircon domains and 2512 22 ma low u zircon domains which reflect an intracrustal melting event the presence of an older crustal remnant ca 2600 ma prior to the formation of the yinshan block is indicated by a 2594 4 ma leucogranite xenolith in the diorite massif and by the widespread presence of ca 2583 3485 ma mostly ca 2700 ma zircon xenocrysts in a variety of volcanic and plutonic rocks an undeformed pegmatite dike in high mg andesite has an emplacement age of 2508 17 ma zircon an undeformed trondhjemite dike that cuts the supracrustal greenstone sequence yielded a zircon age of 2502 6 ma similar to that of the pegmatite dike and representing the latest archean magmatic event in the yinshan block these ages of undeformed granitoid dikes delimit the termination of thermo tectonic development of the yinshan block based on these new ages and published geological and geochronological data we conclude that the yinshan block is a typical neoarchean cratonic block not a segment of the so called paleoproterozoic inner mongolia north hebei orogen episodic mantle melting and resultant crustal reworking account for the thermo tectonic development of the yinshan block in a brief period ca 2556 2502 ma in the late neoarchean and based on their regional chronological correlations we argue for their craton scale significance

the influence of gravity waves on the slope of the kinetic energy spectrum in simulations of idealized midlatitude cyclones abstractthe influence of gravity waves generated by surface stress and by topography on the atmospheric kinetic energy ke spectrum is examined using idealized simulations of a cyclone growing in

mesoscale spectrum of atmospheric motions investigated in a very fine resolution global general circulation model 1 the horizontal spectrum of wind variance conventionally referred to as the kinetic energy spectrum is examined in experiments conducted with the atmospheric gcm for the earth simulator afes global spectral general circulation model we find that the control version of afes run at t639 horizontal spectral resolution simulates a kinetic energy spectrum that compares well at large scales with global observational reanalyses and at smaller scales with available aircraft observations at near tropopause levels specifically there is a roughly 3 power law dependence on horizontal wave number for wavelengths between about 5000 and 500 km transitioning to a shallower mesoscale regime at smaller wavelengths this is seen for both one dimensional spectra and for the two dimensional total wave number spectrum based on a spherical harmonic analysis the simulated spectrum at midtropospheric levels is similar in that there is a transition to a shallower mesoscale regime but the spectrum in the mesoscale is clearly steeper at midtroposphere than near the tropopause there seem to be no extensive observations of horizontal spectra available in the midtroposphere so it is not known whether the contrast seen in the model between upper and mid tropospheric levels is realistic the dependence of the model simulated variability on the subgrid scale moist convection parameterization is examined the space time variability of rainfall is shown to depend strongly on the convection scheme employed the tropospheric kinetic energy spectrum in the mesoscale seems to be correlated with the precipitation behavior so that in a version with a more variable precipitation field the kinetic energy in the mesoscale is enhanced this suggests that the mesoscale motions in the model may be directly forced to a significant extent by the variability in the latent heating field experiments were also performed with a dry dynamical core version of the model run at both t639 and t1279 resolutions this version also simulated a shallow mesoscale range supporting the view that the mesoscale regime in the atmosphere is energized at least in part by a predominantly forward i e downscale nonlinear spectral cascade experiments with various formulations of the hyperdiffusion horizontal mixing parameterization show that the kinetic energy spectrum over about the last half of the resolved wave number range is under strong control by the parameterized mixing however the t1279 model simulates almost a decade of the shallow mesoscale regime i e for horizontal wavelengths from about 80 to 500 km that appears to be fairly independent of the diffusion employed finally experiments are conducted in the dry version to see the effects on the kinetic energy spectrum of changing the thermal rossby number for the simulations

studies on geology and geochemistry of alteration type ore in hatu gold deposit western junggar xinjiang nw china hatu gold deposit locating in west junggar of xinjiang is composed of quartz vein type orebody and alte ration type orebody in this paper we study the alteration type orebody which mainly locates in the deep part of hatu mine albitization pyritization arsenopyritization carbonation sericitization and chloritization are widespread in the alteration type orebody gold mineralization is closely related to pyritization arsenopyritization and carbonation pyrite arsenopyrite chalcopyrite sphalerite pyrrhotite and native gold are major metallic minerals native gold generally occurs in the boundary of arsenopyrite grains or as inclusions in pyrites the ore forming process of alteration type orebody can be divided into five stages quartz albite stage pyrite albite stage arsenopyrite carbonate stage chalcopyrite carbonate stage and quartz calcite stage stage and are main periods for gold deposition chalcopyrite carbonate stage also corresponds with gold deposition basalts are enriched in ba rb pb and sr the chondrite normalized ree patterns of variously altered basalts are similar the chondrite normalized ree pattern of quartz albite veins in alteration type orebody are right inclined and characterized by slightly positive eu anomalies with slight fractio nation between lree and hree the chondrite normalized ree pattern of quartz calcite vein is also right inclined with evidently positive eu anomalies and evident fractionation between lree and hree conclud that the ore forming fluid was gradually enriched in lree with evidently positive eu anomaly

wavelet analysis of dynamical processes in cirrus vertical air velocity observations obtained from the nasa dc 8 on 21 april 1996 are analyzed using wavelet and spectral analysis methods wavelet analysis yielded a very useful characterization of the complex dynamical structures encountered above below and within the cirrus clouds observed on this flight intermittent small groups of apparent gravity waves were found at length scales ranging from 2 km to greater than 40 km within the cloud patches of convective cells were also found the hierarchy of dynamical structures was well discriminated by the analysis

balloon borne observations of short vertical wavelength gravity waves and interaction with qbo winds the quasi biennial oscillation qbo a ubiquitous feature of the zonal mean zonal winds in the equatorial lower stratosphere is forced by selective dissipation of atmospheric waves that range in

sources of mesoscale variability of gravity waves part i topographic excitation abstract aircraft measurements of winds and temperatures collected during the gasp program are used to study the effects of topography as a source of mesoscale variability variances of fluctuations at the mesoscale over rough terrain are enhanced up to nearly two orders of magnitude compared to nonsource regions in some cases and are frequently enhanced by an order of magnitude the implications of these episodic enhancements of variances for the vertical transports of energy and momentum are considered in the framework of gravity wave theory the observed flight data are used to estimate the momentum flux u w on several flight segments results show that the flux is generally negative with mean value 0 26 m2 s 2 and with magnitudes ranging up to 1 5 m2 s 2 spectral analysis shows that the largest contributions to the net flux come from horizontal scales of 25 x 60 km finally the observed momentum fluxes are used to infer the anisotropy factor of gravity waves over rough terrain which is foun

an investigation of terrain effects on the mesoscale spectrum of atmospheric motions abstract wind and temperature data collected on commercial aircraft during the global atmospheric sampling program gasp are used to investigate the effects of underlying terrain on mesoscale variability and the observational results are interpreted within the theories of gravity wave motions and quasi two dimensional turbulence the data show the variances are up to six times larger over mountainous terrain than over oceans or plains with the most striking differences at horizontal scales from 4 to 80 km results were subdivided between the stratosphere and troposphere and between high and low background wind speed cases and show basically the same response to topography in all cases the linear theory of gravity waves is found to predict correctly the scaling of wave amplitude with background stability in the case of low background wind speeds while the two dimensional turbulence theory correctly predicts the shape of the variance spectrum and the observed amplitude scales with as required by t

vertical motions in arctic mixed phase stratiform clouds abstract the characteristics of arctic mixed phase stratiform clouds and their relation to vertical air motions are examined using ground based observations during the mixed phase arctic cloud experiment mpace in barrow alaska during fall 2004 the cloud macrophysical microphysical and dynamical properties are derived from a suite of active and passive remote sensors low level single layer mixed phase stratiform clouds are typically topped by a 400 700 m deep liquid water layer from which ice crystals precipitate these clouds are strongly dominated 85 by mass by liquid water on average an in cloud updraft of 0 4 m s 1 sustains the clouds although cloud scale circulations lead to a variability of up to 2 m s 1 from the average dominant scales of variability in both vertical air motions and cloud microphysical properties retrieved by this analysis occur at 0 5 10 km wavelengths in updrafts both cloud liquid and ice mass grow although the net liquid mass growth is usually largest betwee

vertical velocities and turbulence in midlatitude anvil cirrus a comparison between in situ aircraft measurements and ground based doppler cloud radar retrievals this study introduces a statistical comparison of vertical velocity observations within cirrus from aircraft and ground based doppler cloud radar two cases of midlatitude anvil cirrus forming under very similar environmental conditions are examined the case studies benefit from simultaneous observations of vertical velocities in cirrus collected at and around the atmospheric radiation measurement southern great plains site during the u s department of energy small particles in cirrus field campaign observations from both platforms suggest that the majority of vertical velocities in the examined midlatitude anvil cirrus cases are roughly within 1 m s 1 although higher vertical velocities are occasionally observed the quality of the vertical velocity comparison between in situ aircraft measurements and ground based doppler radar retrievals depends on the case for the first case on 23 april 2010 the comparison suggests that the radar retrieval may underestimate vertical velocities in the range between roughly 50 cm s 1 and 1 m s 1 for the second case on 14 june 2010 the agreement between radar and aircraft is excellent and the differences are largely within the observed variability of vertical velocities within cirrus differences in the spatial scales of vertical velocities and turbulence sampled by the aircraft and doppler radar which arise due to differences in the temporal resolution of the observational platforms are not found to explain the observed discrepancies estimates for the dissipation rate of turbulent kinetic energy agree to within 1 order of magnitude between the two observational platforms

further study of terrain effects on the mesoscale spectrum of atmospheric motions abstract wind and temperature data collected on commercial airliners are used to investigate the effects of underlying terrain on mesoscale variability these results expand upon those of nastrom et al by including all available data from the global atmospheric sampling program gasp and by more closely focusing on the coupling of variance with the roughness of the underlying terrain over mountainous regions the earlier results showing that variances are larger over mountains than over oceans or plains with greatest increases at wavelengths below about 80 km are confirmed statistical tests are used to confirm that these differences are highly significant over mountainous regions the roughness of the underlying terrain was parameterized from topographic data and it was found that variances are highly correlated with roughness and in the troposphere with background wind speed average variances over the roughest terrain areas range up to about ten times larger than those over the oceans these re

gravity waves over antarctica and the southern ocean consistent momentum fluxes in mesoscale simulations and stratospheric balloon observations stratospheric balloons from the vorcore campaign have provided a unique description of the gravity wave field in the lower stratosphere above antarctica and the southern ocean during the austral spring of 2005 mesoscale simulations are carried out to analyze further the gravity wave field first the realism of the simulated waves is assessed by comparison to the observations a satisfactory overall agreement is found but different behaviour is noted for orographic waves overestimation in the simulations relative to the observations and non orographic waves underestimation second the gravity wave field is analyzed in more detail than was possible from observations alone it is necessary to distinguish and quantify orographic and non orographic waves separately orographic waves are larger and more intermittent yet affect only a limited geographical region hence although orographic sources stand out as hot spots for gravity waves their contribution to momentum fluxes entering the stratosphere is comparable to or smaller than the contribution of non orographic sources a diagnostic for intermittency the gini coefficient is proposed it clearly marks the distinction between orographic and non orographic sources intermittencies of 0 8 and 0 5 respectively sensitivity to resolution is quite small regarding the spatial structure of the gravity wave field but is significant for the amplitudes the momentum flux values increase by 2 when the horizontal resolution is doubled and possible biases of both simulations and observations are discussed nonetheless the good agreement between observations and simulations and the complementary information on the biases of each dataset promises that in the future these different estimates of gravity wave momentum fluxes may converge copyright 2012 royal meteorological society

geochemical characteristics and possible origins of the southern closepet batholith south india the polyphase closepet batholith in south india intrudes archean tonalitic and granitic gneisses in a terrane that grades from amphibolite to granulite grade at the southern end of the batholith two granite and two granodioritic suites are recognized in the batholith one granite suite from the southern terminus of the batholith has high sr ba la yb and eu eu and low sc y nb ta and total ree and is similar to other granites from along the amphibolite granulite transition zone that have the characteristics of a fractionally crystallized cumulate the other granite suite has lower sr and ba higher sc and y and no distinctive eu anomaly this latter group which is widespread in the southern closepet batholith can be derived by 20 equilibrium partial melting of a tonalite source containing hornblende and garnet that is compositionally similar to south india tonalites near the amphibolite granulite transition the two granite groups may have been produced by separate episodes of co 2 metam

geochemistry and origin of archean granites from the black hills south dakota the little elk granite 2549 ma and granite at bear mountain bmg 2 5 ga of the black hills formed as a result of a collisional event along the eastern margin of the wyoming province during th

small scale wind fluctuations in the tropical tropopause layer from aircraft measurements occurrence nature and impact on vertical mixing abstractthe contribution of turbulent mixing to heat and tracer transport in the tropical tropopause layer ttl is poorly constrained partly due to a lack of direct observations here the authors use high resolution 20 hz airborne measurements to study the occurrence and properties of small scale 100 m wind fluctuations in the ttl 14 19 km over the tropical pacific the fluctuations are highly intermittent and appear localized within shallow 100 m patches furthermore active turbulent events are more frequent at low altitude near deep convection and within layers of low gradient richardson number a case study emphasizes the link between the turbulent events and the occurrence of inertio gravity waves having small horizontal or vertical scale in order to evaluate the impact of the observed fluctuations on tracer mixing their characteristics are examined during active events they are in broad agreement with inertial range turbulence theory the motions are close to 3d isotropic and the sp

hydrostatic vertical velocity and incompressibility in the northern hemisphere the vertical velocity w is evaluated for the northern hemisphere from reanalysis data and two forms of the richardson equation this equation is based on the hydrostatic assumption and the thermodynamic energy equation the standard form of the richardson equation allows one to quantify the contributions to the vertical velocity of the horizontal divergence

the horizontal spectrum of vertical velocities near the tropopause from global to gravity wave scales abstractvertical motions are fundamental for atmospheric dynamics compared to horizontal motions the horizontal spectrum of vertical velocity w is less well known here w spectra are related to

assessment of the accuracy of re analyses in the equatorial lower stratosphere the accuracy of horizontal winds and temperature in the equatorial lower stratosphere is evaluated in different re analyses european centre for medium range weather forecasts ecmwf operational analysis era interim and modern era retrospective analysis for research and applications using an independent data set collected at low latitudes during long duration balloon flights in early 2010 the three analyzed wind products are found significantly less accurate than in the extratropics with periods of 10m sdisagreement with the observations lasting several days to highlight the dynamical context in which the major disagreement events occur case studies are carried out the events are shown to be related to an improper representation of large scale equatorial kelvin and yanai wave packets with vertical wavelengths smaller than 5 km such events can induce large errors on trajectories computed with analyzed winds relatively to the actual balloon trajectory 4000 km separation after 5 days of calculation reasons for analyses inaccuracy are discussed the vertical resolution of the underlying model likely plays a role but the main factor responsible for deficiencies appears to be the lack of wind observations indeed errors in analyzed winds during the campaign have a strong longitudinal structure with root mean square errors twice as large over the indian ocean and western pacific poorly covered by radiosounding stations as over the maritime continent or south america for the ecmwf analysis this structure mirrors that of the analysis increments which have largest amplitudes over observed regions we argue that the reported events are more likely to happen during maximum shear phases of the quasi biennial oscillation

vertical diffusivity in the lower stratosphere from lagrangian back trajectory reconstructions of ozone profiles 1 we present a simple stochastic dynamical approach to estimate the turbulent vertical diffusivity d in the lower stratosphere from routinely observed ozone profiles first an observed ozone profile is reconstructed using three dimensional back trajectories obtained from analyzed winds and initializing the trajectories with ozone values from the output of a chemistry transport model assuming that diffusion in the vertical follows a simple random walk leading to a gaussian probability distribution for the particle displacements we perform monte carlo simulations with ensembles of particles originating along each point in the vertical profile by choosing different values of d as input in the calculations we generate different profiles that are smoothed through diffusion comparing with the observed profile we can identify that value of d which is in best agreement at an intermediate range of vertical length scales as an upper bound of the actual d for northern midlatitude lower stratospheric conditions during winter over a period of 12 days the best estimate is d 0 1 m2 s 1 or slightly larger the present results are discussed in the context of comparable estimations of vertical diffusivity in the literature

sulphur isotope geochemistry of black shale hosted antimony mineralization arnsberg northern rhenish massif germany implications for late stage fluid flow during the variscan orogeny vein type and bedding concordant mesothermal 180 410 c stibnite sulphosalt mineralization at arnsberg ne rhenish massif germany is hosted by carboniferous pyrite rich black shales and siliceous limestones a detailed sulphur isotope study of the stibnite sulphosalt mineralization and pyrite from a variety of regional host rock lithologies has been carried out using an in situ laser combustion technique the 34 s values of stibnite of various textural types are distinctly negative and lie in a narrow range between 23 9 and 17 1 mean 20 1 in contrast regional sedimentary diagenetic pyrites display a large variation of their 34 s values between 45 4 and 9 3 there is little evidence for significant modification of the hydrothermal fluid during deposition and the s isotope signatures suggest that the sulphur of the stibnite mineralization was not locally derived the 34 s values of pyrite in givetian shales display a significantly narrower range of 28 2 to 7 5 and their mean composition 17 1 is close to the 34 s values of the arnsberg stibnite deposits considering the temperature dependent isotopic fractionation between stibnite and reduced sulfur species the 34 s values of the mineralizing fluid 16 8 200 c and the givetian rock source are essentially identical therefore we propose a model of leaching and isotopic homogenization of sulphur from the middle devonian shales and a subsequent northward migration of these fluids the fluids were trapped in permeability controlled positions within anticlinal zones where fluid cooling induced deposition of stibnite and sulphosalts

plate tectonics 2 5 billion years ago evidence at kolar south india the archean kolar schist belt south india is a suture zone where two gneiss terranes and at least two amphibolite terranes with distinct histories were accrted amphibolites from the eastern and western sides of the schist belt have distinct incompatible element and isotopic characteristics sugesting that their volcanic protoliths were derived from dint mantle sources the amphibolite and gneiss terranes were juxtaposed by horizontal compression and shearing between 2530 and 2420 million years ago ma along a zone marked by the kolar schist belt this history of accretion of discrete crustal terranes resembles those of phanerozoic convergent margins and thus suggests that plate tectonics operated on earth by 2500 ma

the use of structure functions and spectra from numerical model output to determine effective model resolution abstract the effective model resolution of three numerical weather prediction nwp models is determined from analyses of spatial structure functions and spatial spectra in this paper the effective resolution is defined as the dimensions of the rectangular spatial filter that describes the net effect of all of the nwp model s numerical filtering and smoothing effects these effects are determined by comparison of spatial statistics of the nwp model output with statistical climatologies derived from aircraft data for the upper troposphere and lower stratosphere the comparisons are based on both spatial structure functions and spatial spectra the structure function approach has fewer assumptions and fewer numerical artifacts accurate estimates of nwp effective model resolution require a robust climatology of the spatial statistics which are a function of latitude and location such as over mountainous regions an artifact in the climatology of the velocity statistics resulting from mountain waves is i

measuring area averaged vertical motions with dropsondes abstractmeasurements of vertical profiles of areal mean mass divergence vorticity and vertical velocity based on dropsondes distributed over an area of 25 000 km2 are presented the dropsondes

the quebec antimony deposit an example of gudmundite native antimony mineralization in the ophiolitic melange of the southeastern quebec appalachians the quebec antimony deposit contains a rare type of mineral association in which gudmundite fesbs is the main antimony ore mineral and native antimony is common gudmundite is intimately associated with ferroan dolomite and pyrrhotite as early impregnations in the host rocks at the margin of veins and in silicified fault zones whereas native antimony occupies the cores of these structures and is practically devoid of associated iron bearing phases hypogene stibnite kermesite sb 2 s 2 o valentinite orthorhombic sb 2 o 3 and senarmontite cubic sb 2 o 3 formed at the expense of the earlier antimony phases during a late replacement stage the deposit is hosted by altered quartzofeldspathic rocks of the caldwell group at their contact with serpentinites of the lac nicolet ophiolitic complex southeastern quebec the antimony mineralization may have formed at a late stage of the acadian orogeny during a brittle south southeast north northwest directed compressive event unusual physicochemical conditions must account for ore deposition in this type of deposit the paragenesis and presence of methane rich fluid inclusions indicate that conditions were strongly reducing during the main stage of the ore forming process we propose that elevated ch 4 and h 2 fugacities resulted from fluid rock interaction and or from mixing with fluids derived from the nearby serpentinite bodies in contrast fluids responsible for late stibnite kermesite and sb oxides were oxidizing and relatively iron poor

multistage au as sb mineralization and crustal scale fluid evolution in the kwekwe district midlands greenstone belt zimbabwe a combined geochemical mineralogical stable isotope and fluid inclusion study the kwekwe district comprises the central part of the archean midlands greenstone belt of zimbabwe and represents one of few archean gold provinces in the world hosting gold deposits associated with massive antimony mineralization the deposits typically occur along late archean transcrustal deformation zones mineralization is characterized by an early au as stage 1 followed by a pronounced au sb stage 2 and a low grade sb bearing stage 3 four gold deposits within the kwekwe district have been studied the primrose and globe and phoenix gold deposits display typical features of archean orogenic lode gold systems such as fluid inclusions with low salinity mixed aqueous carbonic fluids formation temperatures between 300 and 400 c and a common stable isotope composition of fluid and mineral precipitates deposits of this type formed in the brittle ductile crustal transition zone at 1 5 to 3 0 kbars in contrast gold mineralization at jojo and especially the indarama gold deposits probably formed at lower temperatures 300 c and from dominantly aqueous early moderate to late high salinity fluids at indarama microthermometric studies indicate stibnite gold mineralization at temperatures between 120 and 230 c at about 0 8 to 1 8 kbars low formation temperatures and extremely low 34s values of pyrite 52 and stibnite 36 of the latest mineralization stage at indarama reveal reactivation of the hydrothermal system within a near subsurface organic rich epithermal or hot spring type environment during the late archean or even early proterozoic such low 34s values have not been reported previously from gold deposits in archean greenstone belts we propose that hydrothermal activity and gold mineralization has not only taken place at different crustal levels but also at different times

seasonal variability of vertical eddy diffusivity in the middle atmosphere 1 three year observations by the middle and upper atmosphere radar the vertical eddy diffusivity k due to atmospheric turbulence with spatial scales of 100 102 m has been computed from the echo power spectral width observed by the middle and upper atmosphere radar for almost every month from january 1986 to december 1988 the method of analysis follows lilly et al 1974 sato and woodman 1982 and hocking 1983a 1985 1988 and the contamination due to beam broadening vertical shear and transience has been removed although observations for horizontal wind speeds larger than approximately 40 m s such as occur near the tropopause jet stream in winter have been omitted because of excessive beam broadening sufficient numbers of observations have been accumulated to produce a reasonable climatology for the upper troposphere and lower stratosphere 6 20 km altitude and for the mesosphere 60 82 km altitude the monthly median of k shows a local maximum near the tropopause jet stream altitude it becomes larger in the mesosphere increasing gradually with height maxima of k are observed in winter near the tropopause and in summer in the mesosphere and the seasonal variability of k reaches approximately an order of magnitude a semiannual variability is apparent in the mesosphere with minima in the equinoctial seasons

the dynamics of mesoscale winds in the upper troposphere and lower stratosphere spectral analysis is applied to infer the dynamics of mesoscale winds from aircraft observations in the upper troposphere and lower stratosphere two datasets are analyzed one collected aboard commercial aircraft and one collected using a dedicated research aircraft a recently developed wave vortex decomposition is used to test the observations consistency with linear inertia gravity wave dynamics the decomposition method is shown to be robust in the vicinity of the tropopause if flight tracks vary sufficiently in altitude for the lower stratosphere the decompositions of both datasets confirm a recent result that mesoscale winds are consistent with the polarization and dispersion relations of inertia gravity waves for the upper troposphere however the two datasets disagree only the research aircraft data indicate consistency with linear wave dynamics at mesoscales the source of the inconsistency is a difference in mesoscale variance of the measured along track wind component to further test the observed flow s consistency with linear wave dynamics the ratio between tropospheric and stratospheric mesoscale energy levels is compared to a simple model of upward propagating waves that are partially reflected at the tropopause for both datasets the observed energy ratio is roughly consistent with the simple wave model but wave frequencies diagnosed from the data draw into question the applicability of the monochromatic theory at wavelengths smaller than 10 km

dynamical structure and turbulence in cirrus clouds aircraft observations during fire abstract aircraft data collected during the first international satellite cloud climatology project regional experiment fire i are used to examine dynamical processes operating in cirrus cloud systems observed on 19 and 28 october 1986 measurements from lagrangian spiral soundings and constant altitude flight legs are analyzed comparisons are made with observations in clear air each cirrus case contained a statically stable layer a conditionally unstable or neutrally stratified layer ice pseudoadiabatic in which convection was prevalent and a neutral layer in which convection was intermittent the analysis indicates that a mixture of phenomena occurred including small scale convective cells gravity waves 2 9 km quasi two dimensional waves 10 20 km and larger two dimensional mesoscale waves 100 km the intermediate scale waves observed both in clear air and in the cloud systems likely played an important role in the development of the cloud systems given the magnitude of the associ

the biards sb au bearing shear zone massif central france an indicator of crustal scale transcurrent tectonics guiding late variscan collapse structural textural mineralogic microthermometric and isotopic data obtained on the biards sb au district located in the south limousin area massif central france provide new evidence for the tectonic setting of stibnite and gold deposition during the late orogenic variscan collapse in western europe a variety of geologic and geophysical data define a major crustal scale left lateral strike slip shear zone that acted as a trap for sb au mineralization during these movements fault fill veins and then extensional veins of limited extent were created along rheologic heterogeneities that focused brittle deformation geometry and orientation of both vein sets indicate two main episodes of emplacement of ore related to a progressive wrench movement in response to an counterclockwise rotation of the regional stress axes both veins sets are filled by quartz and sulfides in three stages an early arsenopyrite pyrite stage with fine grained quartz a sphalerite pb sb sulfosalt native gold stage with comb quartz and a late stibnite berthierite stage with comb quartz combined fluid inclusion and stable isotope studies on quartz muscovite and sulfides reveal that the three stages result from the continuous evolution of a deep seated hydrothermal system in which the latest stages mixed with meteoric water these data argue for cooling and a pressure drop during ore deposition and indicate a shallow level of emplacement for sb au veins a comparison of the biards deposits with other upper paleozoic gold and antimony deposits in the massif central the western variscides and elsewhere in the world illustrates their common association with crustal scale strike slip shear zones the upper carboniferous age 305 300 ma of the sb au deposits indicates that they formed during the early stages of the postthickening extension of the variscan lithosphere sb au bearing strike slip shear zones resulted from the late variscan crustal collapse guided by the very large scale dextral shearing between central europe northern africa and the northern appalachians and associated with the opening of the paleo tethys and the closing of the theic ocean during the late paleozoic gondwana laurasia translation

the coupled geochemistry of au and as in pyrite from hydrothermal ore deposits the ubiquity of au bearing arsenian pyrite in hydrothermal ore deposits suggests that the coupled geochemical behaviour of au and as in this sulfide occurs under a wide range of physico chemical conditions despite significant advances in the last 20years fundamental factors controlling au and as ratios in pyrite from ore deposits remain poorly known here we explore these constraints using new and previously published empa la icp ms sims and pixe analyses of as and au in pyrite from carlin type au epithermal au porphyry cu cu au and orogenic au deposits volcanogenic massive sulfide vhms witwatersrand au iron oxide copper gold iocg and coal deposits pyrite included in the data compilation formed under temperatures from 30 to 600 c and in a wide variety of geological environments the pyrite au as data form a wedge shaped zone in compositional space and the fact that most data points plot below the solid solubility limit defined by reich et al 2005 indicate that au1 is the dominant form of au in arsenian pyrite and that au bearing ore fluids that deposit this sulfide are mostly undersaturated with respect to native au the analytical data also show that the solid solubility limit of au in arsenian pyrite defined by an au as ratio of 0 02 is independent of the geochemical environment of pyrite formation and rather depends on the crystal chemical properties of pyrite and post depositional alteration compilation of au as concentrations and formation temperatures for pyrite indicates that au and as solubility in pyrite is retrograde au and as contents decrease as a function of increasing temperature from 200 to 500 c based on these results two major au as trends for au bearing arsenian pyrite from ore deposits are defined one trend is formed by pyrites from carlin type and orogenic au deposits where compositions are largely controlled by fluid rock interactions and or can be highly perturbed by changes in temperature and alteration by hydrothermal fluids the second trend consists of pyrites from porphyry cu and epithermal au deposits which are characterised by compositions that preserve the au as signature of mineralizing magmatic hydrothermal fluids confirming the role of this sulfide in controlling metal ratios in ore systems

as sb bi au mineralization in the baogutu gold deposit xinjiang nw china here we report the occurrence of some uncommon mineral assemblages including paakonenite aurostibite native arsenic native antimony and native bismuth found in the baogutu gold deposit in the western junggar xinjiang nw china the mineralization could be generally subdivided into two types the gold bearing quartz vein type mineralization and disseminated mineralization in the wall rocks the sulfide minerals in gold lodes commonly include pyrite arsenopyrite marcasite and stibnite however the l7 lode in no 4 orebody and the l1 lode in no 11 orebody of the baogutu gold deposit are quite different in terms of their mineral assemblages the l7 lode contains native arsenic quartz veins in shallow levels and stibnite quartz veins at depth gold bearing minerals electrum native gold and rarely aurostibite mainly coexist with paakonenite stibnite native arsenic and native antimony the crystallization of as and sb bearing minerals was likely to have consumed h2s from the hydrothermal fluid which probably triggered the precipitation of native gold the l1 lode consists of several discontinuous sulfide dominated lensoid orebodies the massive sulfide ores that produced most of the gold resource are characterized by an intimate association between native bismuth and native gold mineralization

comparative petrogenesis and tectonics of paleoproterozoic malanjkhand and dongargarh granitoids central india abstract the malanjkhand granitoid mg and two units of dongargarh granitoids dgs represent contemporaneous episodes of paleoproterozoic felsic magmatism in the bastar craton central india a comparative geochemical study is carried out between the mineralized malanjkhand granitoid mg and barren dongargarh granitoids dgs that occur adjacent to each other separated by the dongargarh group of rocks major element oxides geochemistry reveals that mg is granite granodiorite whereas dg is strictly granite in composition and both plutons show calc alkaline affinity geochemical discrimination indicates that mg is an i type whereas an a type affinity can only be suspected in case of dg and both can be labeled as peraluminous trace element data from these paleoproterozoic granitoids indicate that they evolved in a tectonic environment similar to continental rift setting hfse ratios suggest variable degree of fractionation of highly differentiated granitic magma was a very complex crystallization process results in the formation of these two granitoids by common mechanism possibly fluid separation might be involved highly fractionated ree and depleted mree patterns with eu anomaly absent in mg and negative in dg inferred that the parental magma derived by low degree partial melting of heterogeneous mafic source probably amphibolitic in nature followed by progressive differentiation zircon saturation temperature and zr content reveals that mg crystallized from wet melt whereas dg crystallized from relatively dry melt but both are classify as hot granites thermobarometric calculations indicates that mg has emplaced at upper level whereas dg at relatively deeper or middle upper level in the continental crust the origin of palaeoproterozoic granitoids in central india has attributed to the magma mixing process between crustal derived felsic and mafic magma contributed by basaltic underplating in a continental rift environment

mineralogy fluid inclusion and stable isotope constraints on the genesis of the roudný au ag deposit bohemian massif orogenic gold deposits with gold of low fineness are relatively rare in the bohemian massif but occur locally within the late variscan blanice graben structure in the moldanubian zone among them the roudn deposit has been the most important with total production of about 6 t of gold between 1895 and 1930 the ore is related to an irregular quartz stockwork and is represented by sulfide and electrum impregnations within the quartz gangue and the altered host rocks ore grade varies from 4 to 25 g t au the gold is present as macro and microscopic electrum fineness 658 665 and also as invisible gold in the crystal structure of early sulfides as rich pyrite and sb rich arsenopyrite three mineralization stages have been distinguished 1 the largely barren pre ore stage 2 the main ore stage with economic au ag mineralization 3 the late stage with subeconomic ag pb zn mineralization fluid inclusion and mineral thermometry indicate that the three stages were formed at about 400 to 330 350 to 250 and 250 to 70 c respectively early mineralization stages are related to complex h2o co2 ch4 n2 low salinity 3 9 wt nacl equiv fluids with isotopic signatures consistent with a metamorphic origin 18ofluid 4 7 2 9 smow most of the main ore stage minerals including the electrum precipitated from aqueous fluids 2 4 wt nacl equiv during the late mineralization stage the salinity of aqueous fluid was higher 7 9 wt nacl equiv the isotopic composition of the late fluid however also records gradually increasing proportions of meteoric water 18ofluid 2 to 1 smow elevated arsenic contents 120 210 ppm as were found in aqueous carbonic fluids by the la icp ms technique models of fluid mixing at the transition of the main to late mineralization stages are used to estimate the temperature and paleogeothermal gradient possible ages of electrum mineralization 300 to 275 ma and ag pb zn vein type mineralization 275 to 265 ma are discussed overall the roudn deposit shows striking similarities with 300 ma gold deposits of the french massif central

geochemistry and origin of the archaean beit bridge complex limpopo belt south africa the beit bridge complex bbc in the central zone of the limpopo belt in southern africa includes metasedimentary rocks of archaean age chiefly metapelites quartzites and carbonates amphibolites chiefly mafic dykes and sills and granitoids which comprise 50 of the complex the amphibolites are tholeiites with relatively unfractionated ree patterns and pronounced subduction zone geochemical signatures in terms of relatively immobile incompatible elements tonalites and granites which also exhibit such a signature can be formed by batch melting of a mafic source with residual garnet or amphibole most granites have negative eu anomalies and appear to represent residual liquids bbc metapelites have negative eu anomalies and other immobile element distributions similar to phanerozoic shales one group of metapelites that shows significant depletion in ca na and sr appears to have been derived from intensely weathered sources the negative eu anomalies in bbc metapelites suggest intracrustal melting of their sources and thus the presence of evolved continental crust in this part of southern africa by about 3000 ma bbc quartzites are quartz rich sandstones that are depleted in hfs elements ba and sr relative to phanerozoic counterparts a feature that probably reflects less recycling during the early archaean bbc banded iron formation bif is similar to other archaean bif and shows large positive eu anomalies bbc carbonates are dolostones depleted in ree hfs elements u th ba sr ni sc v and y and enriched in fe mn na rb and cs relative to phanerozoic marine carbonates

gold enrichment and the bi au association in pyrrhotite rich massive sulfide deposits escanaba trough southern gorda ridge high gold contents to 10 1 ppm avg 1 4 ppm n 34 occur in pyrrhotite rich massive sulfide samples from the sediment covered floor of the escanaba trough the slow spreading southernmost segment of gorda ridge these concentrations reflect the presence of primary gold formed during high temperature hydrothermal activity in mounds and chimneys and secondary gold deposited during sea floor weathering of massive sulfide primary gold occurs as fine grained 2 m secondary gold grains have a porous flaky morphology and occur in samples in which pyrrhotite is oxidized and replaced by fe oxyhydroxides fe sulfate and sulfur mounds and chimneys dominated by pyrrhotite and containing lesser amounts of isocubanite chalcopyrite and fe rich sphalerite were formed by high temperature estimated range 325 275 c reduced low sulfur vent fluids the mineral and fluid compositions during this main stage of hydrothermal venting reflect subsurface interaction between circulating hydrothermal fluids and turbiditic sediment containing as much as 1 1 percent organic carbon as the deposition of pyrrhotite cu fe sulfides and sphalerite waned a volumetrically minor suite of sulfarsenide arsenide bi and au minerals was deposited from highly reduced late main stage fluids diffusing through mounds and chimneys the low solubility of au as a bisulfide complex and the absence of fluid mixing during this stage of hydrothermal activity apparently inhibited the precipitation of gold directly from solution instead gold precipitation is thought to be linked to elevated concentrations of bi in the late main stage fluids the textural relationships of au and bi minerals in pyrrhotite rich samples low melting point of native bismuth 271 4 c and recent experimental results on au and bi in hydrothermal fluids contribute to the hypothesis that gold was effectively scavenged from the escanaba trough vent fluids by coexisting droplets of liquid bismuth additional phase relationships of alloys in the au bi system indicate that deposition of native bismuth and maldonite occurred at temperatures as low as 241 c bismuth droplets trapped in void space between main stage mineral grains scavenged gold from ambient hydrothermal fluid to a greater extent than bismuth enclosed by late forming pyrrhotite the limited solid solution of au in bi can explain the apparent exsolution texture in which gold blebs are hosted by native bismuth the electrum native bismuth with gold inclusions and galena represent the last traces of gold mineralization from late main stage fluids during sea floor weathering and the oxidation of pyrrhotite in the mounds and chimneys secondary gold formed as aggregates of colloidal particles along ph gradients between acidic pore waters and ambient seawater gold was mobilized from earlier formed primary gold minerals and transported as aqueous chloride complexes the reduction of au iii by residual fe2 in partly altered pyrrhotite and adsorption of colloids by fe oxyhydroxides may have influenced the location of secondary gold grains within the alteration front solubility differences between gold and silver chloride complexes at low temperature account for the low ag content of secondary gold grains the high concentrations of bi and thus the association of au and bi minerals in pyrrhotite rich massive sulfide can be ascribed to the extensive interaction of hydrothermal fluids with sediment in the escanaba trough in contrast the absence of the au bi association in massive sulfides at other ridges including other sediment covered sites at middle valley and the guaymas basin reflects the predominantly basaltic source rocks

vertical resolution requirements in atmospheric simulation abstractthe role of vertical mesh spacing in the convergence of full physics global atmospheric model solutions is examined for synoptic mesoscale and convective scale horizontal resolutions usi

discovery of antimony and distribution characteristics of associated elements in huize pb zn deposit it has been held that the huize pb zn deposit contains comprehensive useful elements such as ag cd and ge nevertheless the exact contents modes of occurrence and distribution regularity of these elements except for silver are not clear based on systematic observation and sampling of the main orebody the authors conducted rock and mineral identification chemical analysis including analysis of some individual minerals and electron microprobe analysis of the ore rock so as to understand characteristics of mineralization antimony was found for the first time in the ore the mean contents of ag cd ge cu and sb are 121 77 10 6 660 99 10 6 62 10 10 6 203 78 10 6 and 169 87 10 6 respectively and these associated elements were evidently formed at the late stage of mineralization this ore deposit is a multistage hydrothermal deposit

comparison of the native antimony bearing paiting gold deposit guizhou province china with carlin type gold deposits nevada usa the paiting gold deposit guizhou province china has been regarded as a carlin type gold deposit by several researchers alteration and ore related minerals from the paiting deposit were examined and results were compared with the cortez hills carlin type gold deposit nevada usa similarities include the structural and stratigraphic controls on the orebodies in both deposits and the occurrence of invisible gold ionically bound in arsenian pyrite significant differences include the following 1 the gold bearing mineral in nevada is arsenian pyrite however gold bearing minerals in the paiting deposit include arsenopyrite arsenian pyrite and trace pyrrhotite also euhedral or subhedral gold bearing arsenian pyrite at paiting contains significantly less as cu and hg than gold bearing pyrite from nevada 2 alteration in the paiting deposit displays significantly less decarbonatization instead dolomite precipitation which has not been described in nevada deposits is associated with deposition of gold bearing sulfide minerals 3 stibnite and minor native antimony typify paiting late ore stage minerals whereas in nevada realgar orpiment and calcite are common late ore stage minerals precipitation of native antimony in the paiting deposit reflects the evolution of a late ore fluid with unusually low sulfur and oxygen fugacities some characteristics of the paiting gold deposit including formation of ore stage dolomite and precipitation from co2 rich ore fluids at temperatures in excess of 250 c are more typical of orogenic deposits than nevada carlin deposits the presence of similarities in the paiting deposit to both carlin type and orogenic deposits is consistent with formation conditions intermediate to those typical of carlin type and orogenic systems

atmospheric conditions during the deep propagating gravity wave experiment deepwave abstractthis paper describes the results of a comprehensive analysis of the atmospheric conditions during the deep propagating gravity wave experiment deepwave campaign in austral winter 2014 different datasets and diagnostics are combined to characterize the background atmosphere from the troposphere to the upper mesosphere how weather regimes and the atmospheric state compare to climatological conditions is reported upon and how they relate to the airborne and ground based gravity wave observations is also explored key results of this study are the dominance of tropospheric blocking situations and low level southwesterly flows over new zealand during june august 2014 a varying tropopause inversion layer was found to be connected to varying vertical energy fluxes and is therefore an important feature with respect to wave reflection the subtropical jet was frequently diverted south from its climatological position at 30 s and was most often involved in strong forcing events of mountain waves at t

tracking the multiple stage exhumation history and magmatic hydrothermal events of the west junggar region nw china evidence from 40 ar 39 ar and u th he thermochronology abstract to decipher cooling events in the west junggar region biotite and k feldspar 40ar 39ar and zircon and apatite u th he isotopic analyses of intrusive rocks were carried out previous u pb data showed that intrusive bodies in the baogutu area were emplaced at 315 310 ma u pb and zircon u th he dating results 313 241 ma suggest that a magmatic hydrothermal event lasted for 72 ma in the baogutu area of the west junggar region early stage high temperature alteration 900 300 c lasted for 6 2 ma and was followed by prolonged phyllic and argillic alteration lasting 67 63 ma between 350 and 200 c finally slower cooling occurred between 200 and 70 c accompanied by post mineralization uplift and erosion in this study three main episodes of relatively rapid cooling were distinguished in the west junggar region i e late carboniferous early permian 307 277 ma middle triassic 241 232 ma and early cretaceous 145 120 ma the first rapid cooling during the late carboniferous early permian was possibly associated with the release of magmatic heat the middle triassic and early cretaceous cooling and exhumation are interpreted as a response to collision s between the qiangtang and kunlun qaidam or lhasa blocks the cenozoic india eurasia collision however may have had little or no effect on modern tectonic reactivation of the west junggar region