maceral composition and origin of organic matter input in neoproterozoic lower cambrian organic rich shales of salt range formation upper indus basin pakistan abstract the appropriate thermal maturity oil window or lower of the neoproterozoic rocks is a prerequisite for preserving robust and primary biological assemblages the neoproterozoic lower cambrian organic rich shales present in the upper part of salt range formation pakistan with abundant organic matter om total organic carbon toc up to 46 at relatively low thermal maturity protobitumen reflectance bro 0 2 0 4 represents by far the lowest thermal maturity neoproterozoic lower cambrian rocks analyzed to date the detailed petrographic description of neoproterozoic lower cambrian organic matter in the current study was lacking from previous source rock studies of coeval strata from oman eastern siberia australia and elsewhere eight organic rich shales of the salt range formation from three different outcrops have been analyzed for maceral composition and source rock characterization using organic petrography scanning electron microscopy and standard source rock assessment techniques the organic petrography reveals the organic rich shales are predominantly composed of alginites lamalginite and telalginite bituminite protobitumen and mineral bituminous groundmass overall the maceral assemblages suggest the deposition of these shales took place under a salinity stratified water column in a shallow restricted basin where both oxygenic and anoxygenic modes of primary production were operative the top oxygenated part of the water column was populated with the phototropic mat forming cyanobacterium whereas the lower low dissolved oxygen zone was dominated by algal mats and sulphate reduction bacteria the rare and scattered thucholites present within the salt range formation shales were derived from the radiation induced polymerization of adjacent om by the radioactive grains the heat from the radioactive grains however found to have a negligible effect on the overall thermal maturity of these shales

alteration mineralogy and stable isotope geochemistry of paleoproterozoic basement hosted unconformity type uranium deposits in the athabasca basin canada unconformity type uranium deposits are characterized by mineralization developed along the contact between younger sandstone cover and underlying crystalline basement rocks mineralization may extend up to 400 m into the underlying basement rocks whereas sandstone hosted unconformity type deposits have been well studied deposits hosted primarily in the basement have not this study examines the deposits at rabbit lake dawn lake and mcarthur river in the athabasca basin of canada which are hosted by the metamorphic archean and early paleoproterozoic rocks forming the basement to younger late paleoproterozoic sandstones alteration is similar in the three deposits and is characterized by three distinct paragenetic stages 1 preore alteration involving illitization of plagioclase and amphibole followed by chloritization of biotite and illite which formed at ca 230 c 2 ore stage alteration characterized by uraninite and coarse grained illite which formed at ca 240 c 3 postore alteration comprising spherulitic dravite vein chlorite quartz calcite and fe cu co and pb sulfides which formed at ca 135 c fluid circulation associated with emplacement of later mackenzie dikes initiated partial recrystallization of uraninite a later stage of alteration includes kaolinite and iron hydroxide precipitation formed at much lower temperatures of ca 50 c stable isotope compositions of the alteration minerals in conjunction with their paragenesis indicate that oxidized basinal fluids d 43 to 21 18o 3 8 were derived primarily from evolved seawater and leached uranium from the overlying sandstones of the athabasca formation and transported it into the basement via infiltration along fracture zones associated with reverse faults graphitic units in the basement and preore alteration served as both physical fractured zones and chemical reductants traps for the uranium mineralization the basinal fluids were responsible for the preore illite chlorite synore uraninite illite and the early postore alteration events this differs from many other sandstone hosted deposits where both oxidized basinal and reduced basement derived fluids were responsible for uranium precipitation

a shallow convective model for jupiter s alternating wind bands 1 the dynamics of a thin atmospheric layer 1 340 bar below the cloud tops of jupiter is simulated with a three dimensional nonlinear transformed spectral model the gas is compressible and stratified commensurate with the observed emitted radiation from jupiter s atmosphere the transport of the planet s internal energy in the lower region is taken to be convective but solar heating is not accounted for in qualitative agreement with observations the model produces alternating wind bands and a dominant prograde equatorial jet the zonal wind speed at the equator is within a factor of 2 of the observed values

noble gases ar kr xe and halogens cl br i in fluid inclusions from the athabasca basin canada implications for unconformity related u deposits the formation of unconformity related uranium deposits in the proterozoic athabasca basin canada involved basin scale circulation of u bearing brines during high grade diagenesis 150 200 degrees c at similar to 1 6 1 5 ga the uo2 ores occur both sides of the unconformity and are associated with extensive brecciation and illite sudoite dravite alteration quartz and dolomite cementing veins and breccias are associated with alteration and mineralisation and contain a fairly uniform population of fluid inclusions characterised by variable na ca and salinities of 25 35 wt salts and high u concentrations of up to 600 ppm u in order to further constrain the origin of these u rich brines we analysed the naturally occurring isotopes of ar kr and xe together with halogens cl br and i k ca and u in irradiated quartz and dolomite samples containing representative fluid inclusions this was achieved by the noble gas method for halogen measurement extended ar 40 ar 39 methodology using a combination of noble gas extraction techniques the fluid inclusions opened by crushing quartz and dolomite samples in vacuum have similar molar br cl ratios of 5 8 x 10 3 to 10 4 x 10 3 and molar i cl ratios of 1 8 x 10 6 to 8 2 x 10 6 these compositions lie over the top half of the modern day seawater evaporation trajectory consistent with the fluids deriving the bulk of their salinity by subaerial evaporation of seawater beyond the point of halite saturation the i cl ratios are much lower than is typical of fluids that have interacted with i rich organic matter present in many sedimentary basins or fluid inclusions found in mississippi valley type mvt pb zn ore deposits this is significant because provided the u rich fluid inclusions are representative of the ore stage fluids the low i cl ratios of the fluid inclusions do not favour fluid interaction with organic matter or hydrocarbons as a major process for localising u mineralisation the majority of samples contain fluid inclusions with age corrected ar 40 ar 36 of between the modern atmospheric value of similar to 300 and 450 these values are considered representative of the fluid s initial composition and are typical of upper crustal sedimentary formation waters the fluid inclusions nonradiogenic kr 84 ar 36 and xe 129 ar 36 ratios are slightly enriched in xe 129 relative to air and the fluid inclusions are estimated to contain 0 5 17 3 x 10 10 mol g 1 ar 36 which is up to twenty times the ar 36 concentration of air saturated seawater the data are interpreted to reflect acquisition of atmospheric noble gases from sedimentary rocks and suggest acquisition of radiogenic ar 40 within k rich basement rocks that would have been an important source of excess ar 40 was limited by temperatures of less than 200 degrees c taken together the halogen and noble gas composition of the u bearing fluid inclusions are strongly controlled by subaerial evaporation and subsequent interaction with sedimentary rocks showing that low temperature evaporitic brines dominated the mineralising system mineralisation is unlikely to have been triggered by fluid interaction with organic matter or mixing with voluminous basement derived fluids however the data do not completely preclude a role for volumetrically minor fluid or gas phases introduced by deep seated basement faults preferentially located at the sites of mineralisation

jupiter s great red spot as a shallow water system most current models of jupiter s great red spot grs are cast in terms of a two layer model where a thin upper weather layer which contains the vortex overlies a much deeper layer which is meant to represent the neutrally stratified deep atmosphere any motions in the deep layer are assumed to be zonal and steady this two layer model is dynamically equivalent to a one layer model with meridionally varying solid bottom topography called the reduced gravity model specifying the motions or lack thereof in the lower layer of the two layer model is equivalent to specifying the bottom topography and hence the far field potential vorticity in the reduced gravity model current models of the grs start by guessing the deep motions and then proceed to study vortices using the implied bottom topography here using the grs cloud top velocity data we derive the bottom topography up to a constant that depends on the unknown radius of deformation or equivalently the product of the reduced gravity and the mean thickness of the upper layer the bottom topography is inferred from three quantities derived from the velocity data bernoulli streamfunction kinetic energy per unit mass and absolute vorticity all of which are functions only of horizontal position in the reference frame of the vortex far from the vortex potential vorticity versus latitude is calculated from the observed cloud top zonal velocity and the derived bottom topography the results show that the deep atmosphere is in differential motion and that the far field potential vorticity gradient changes sign at several latitudes numerical shallow water experiments are performed using both the derived bottom topography and the bottom topographies prescribed by current models the results of three published studies are reproduced in our numerical experiments each of these models is successful in maintaining a long lived isolated vortex but only the present model yields absolute vorticity profiles along streamlines that agree with those observed for the grs by dowling and ingersoll in all the models large vortices form by merging with smaller vortices in the present observationally based model and in one other published model the smaller vortices arise spontaneously because the observed cloud top zonal velocity profile is unstable these two models require an additional momentum source to maintain the upper layer zonal velocity profile in the other two models the bottom topography stabilizes the zonal velocity profile if dissipation is present the latter two models require an additional source of smaller vortices to maintain the larger one a crucial unanswered question for the present model and for jupiter itself is how the cloud top zonal velocity profile is maintained in its present unstable state

saturn s atmosphere at 1 10 kilometer resolution we present images of saturn from the final phases of the cassini mission including images with 0 5 km per pixel resolution as high as any saturn images ever taken notable features are puffy clouds resembling terrestrial cumulus shadows indicating cloud height dome and bowl shaped cloud structures indicating upwelling and downwelling in anticyclones and cyclones respectively and filaments which are thread like clouds that remain coherent over distances of 20 000 km from the coherence of the filaments we give upper bounds on the diffusivity and kinetic energy dissipation a radiative transfer analysis by sanz requena et al 2018 indicates that methane band imagery is most useful in determining cloud and haze properties in the 60 250 mbar pressure range our methane band imagery finds haze in this pressure range covering 64 74 planetocentric latitude filaments lie within the haze and cumulus clouds lie below it but pressure levels are uncertain below the 250 mbar level

saturn s visible lightning its radio emissions and the structure of the 2009 2011 lightning storms visible lightning on saturn was first detected by the cassini camera in 2009 at 35 south latitude we report more lightning observations at 35 south later in 2009 and lightning in the 2010 2011 giant lightning storm at 35 north the 2009 lightning is detected on the night side of saturn in a broadband clear filter the 2011 lightning is detected on the day side in blue wavelengths only in other wavelengths the 2011 images lacked sensitivity to detect lightning which leaves the lightning spectrum unknown the prominent clouds at the west edge or the head of the 2010 2011 storm periodically spawn large anticyclones which drift off to the east with a longitude spacing of 10 15 10 000 km the wavy boundary of the storm s envelope drifts with the anticyclones the relative vorticity of the anticyclones ranges up to f 3 where f is the planetary vorticity the lightning occurs in the diagonal gaps between the large anticyclones the vorticity of the gaps is cyclonic and the atmosphere there is clear down to level of the deep clouds in these respects the diagonal gaps resemble the jovian belts which are the principal sites of jovian lightning the size of the flash illuminated cloud tops is similar to previous detections with diameter 200 km this suggests that all lightning on saturn is generated at similar depths 125 250 km below the cloud tops probably in the water clouds optical energies of individual flashes for both southern storms and the giant storm range up to 8 10 9 j which is larger than the previous 2009 equinox estimate of 1 7 10 9 j cassini radio measurements at 1 16 mhz suggest that assuming lightning radio emissions range up to 10 ghz lightning radio energies are of the same order of magnitude as the optical energies southern storms flash at a rate 1 2 per minute the 2011 storm flashes hundreds of times more often 5 times per second and produces 10 10 w of optical power based on this power the storm s total convective power is of the order 10 17 w which is uncertain by at least an order of magnitude and probably is underestimated this power is similar to saturn s global internal power radiated to space it suggests that storms like the 2010 2011 giant storm are important players in saturn s cooling and thermal evolution

a three dimensional model of moist convection for the giant planets the jupiter case abstract we present a three dimensional cloud model designed for the study of formation and evolution of moist convective storms on the giant planets this is a finite difference model that solves the dynamic and thermodynamic equations forward in time under the anelastic approximation including microphysics in a parameterized form three dimensional modeling is needed to include the dynamical effects of the vertical and meridional ambient wind shears and the coriolis force on the storm onset and evolution the model is designed to run on the four giant planets to compare how moist convection operates in each case in this paper we present the results for jupiter water ammonia storms under a variety of conditions several improvements in the mathematical formulation and in the numerical methods and an update of the input values e g the thermal profile and gas abundances with respect to previous models have been incorporated we show that under the appropriate relative humidity conditions and particulate precipitation it is possible to create visible storms even with a small deep water abundance of 0 2 times the solar value the effect of the vertical wind shear is important as it is on earth in controlling the structure of the cloud its growing ratio and the local wind field but it has a small influence on the upper level reached by the storm the distribution of the convective cells created in the presence of a vertical wind shear resembles the pattern of mesoscale storms recently observed by galileo

life cycles of spots on jupiter from cassini images using the sequence of 70 day continuum band 751 nm images from the cassini imaging science system iss we record over 500 compact oval spots and study their relation to the large scale motions the 100 spots whose vorticity could be measured the large spots in most cases were all anticyclonic we exclude cyclonic features chaotic regions because they do not have a compact oval shape but we do record their interactions with spots we distinguish probable convective storms from other spots because they appear suddenly grow rapidly and are much brighter than their surroundings the distribution of lifetimes for spots that appeared and disappeared during the 70 day period follows a decaying exponential with time constant mean lifetime of 3 5 days for probable convective storms and 16 8 days for all other spots extrapolating the exponential beyond 70 days seriously underestimates the number of spots that existed for the entire 70 day period this and other evidences size shape distribution in latitude suggest that these long lived spots with lifetime larger than 70 days are from a separate population the zonal wind profile obtained manually by tracking individual features this study agrees with that obtained automatically by correlating brightness variations in narrow latitude bands porco et al 2003 some westward jets have developed more curvature and some have developed less curvature since voyager times but the number of westward jets that violate the barotropic stability criterion is about the same in the northern hemisphere the number of spots is greatest at the latitudes of the westward jets which are the most unstable regions according to the barotropic stability criterion during the 70 day observation period the great red spot grs absorbed nine westward moving spots that originated in the south equatorial belt seb where most of the probable convective storms originate although the probable convective storms do not directly transform themselves into westward moving spots their common origin in the seb suggests that moist convection and the westward jet compose a system that has maintained the grs over its long lifetime

an objective classification of saturn cloud features from cassini iss images abstract a k means clustering algorithm is applied to cassini imaging science subsystem continuum and methane band images of saturn s northern hemisphere to objectively classify regional albedo features and aid in their dynamical interpretation the procedure is based on a technique applied previously to visible infrared images of earth it provides a new perspective on giant planet cloud morphology and its relationship to the dynamics and a meteorological context for the analysis of other types of simultaneous saturn observations the method identifies 6 clusters that exhibit distinct morphology vertical structure and preferred latitudes of occurrence these correspond to areas dominated by deep convective cells low contrast areas some including thinner and thicker clouds possibly associated with baroclinic instability regions with possible isolated thin cirrus clouds darker areas due to thinner low level clouds or clearer skies due to downwelling or due to absorbing particles and fields of relatively shallow cumulus clouds the spatial associations among these cloud types suggest that dynamically there are three distinct types of latitude bands on saturn deep convectively disturbed latitudes in cyclonic shear regions poleward of the eastward jets convectively suppressed regions near and surrounding the westward jets and baroclinically unstable latitudes near eastward jet cores and in the anti cyclonic regions equatorward of them these are roughly analogous to some of the features of earth s tropics subtropics and midlatitudes respectively this classification may be more useful for dynamics purposes than the traditional belt zone partitioning temporal variations of feature contrast and cluster occurrence suggest that the upper tropospheric haze in the northern hemisphere may have thickened by 2014 the results suggest that routine use of clustering may be a worthwhile complement to many different types of planetary atmospheric data analysis

coincident observations of lightning by the forte photodiode detector the new mexico tech lightning mapping array and the nldn during steps 1 opportunities for observation of lightning simultaneously from space and ground are relatively rare one such opportunity for ground truth occurred during the steps field program on 25 june 2000 the forte satellite passed over a storm that was also observed by a vhf lightning mapping array lma of the 190 flashes mapped during the 2 minute 45 second pass 26 had associated satellite optical data and 3 of these were coincident with the only nldn ground strike locations in the storm during that time the maximum height horizontal extent and duration of flashes detected optically tended to be greater than for those flashes not optically detected results in this paper a companion paper and other published papers suggest that at least under some circumstances cg flashes are relatively more likely than intra cloud ic flashes to be observed by an optical sensor in orbit

observations and numerical modelling of a convective disturbance in a large scale cyclone in jupiter s south temperate belt abstract moist convective storms in jupiter develop frequently and can trigger atmospheric activity of different scales from localized storms to planetary scale disturbances including convective activity confined inside a larger meteorological system in february 2018 a series of convective storms erupted in jupiter s south temperate belt stb planetocentric latitudes from 23 to 29 5 this occurred inside an elongated cyclonic region known popularly as the stb ghost close to the large anticyclone oval ba resulting in the clouds from the storms being confined to the cyclone the initial storms lasted only a few days but they generated abundant enduring turbulence they also produced dark features possibly partially devoid of clouds that circulated around the cyclone over the first week the subsequent activity developed over months and resulted in two main structures one of them closely interacting with oval ba and the other one being expelled to the west here we present a study of this meteorological activity based on daily observations provided by the amateur community complemented by observations obtained from planetcam upv ehu at calar alto observatory the hubble space telescope and by junocam on the juno spacecraft we also perform numerical simulations with the epic general circulation model to reproduce the phenomenology observed the successful simulations require a complex interplay between the ghost the convective eruptions and oval and they demonstrate that water moist convection was the source of the initial storms a simple scale comparison with other moist convective storms that can be observed in the planet in visible and methane absorption band images strongly suggests that most of these storms are powered by water condensation instead of ammonia

mid infrared mapping of jupiter s temperatures aerosol opacity and chemical distributions with irtf texes abstract global maps of jupiter s atmospheric temperatures gaseous composition and aerosol opacity are derived from a programme of 5 20 m mid infrared spectroscopic observations using the texas echelon cross echelle spectrograph texes on nasa s infrared telescope facility irtf image cubes from december 2014 in eight spectral channels with spectral resolutions of r 2000 12 000 and spatial resolutions of 2 4 latitude are inverted to generate 3d maps of tropospheric and stratospheric temperatures 2d maps of upper tropospheric aerosols phosphine and ammonia and 2d maps of stratospheric ethane and acetylene the results are compared to a re analysis of cassini composite infrared spectrometer cirs observations acquired during cassini s closest approach to jupiter in december 2000 demonstrating that this new archive of ground based mapping spectroscopy can match and surpass the quality of previous investigations and will permit future studies of jupiter s evolving atmosphere the visibility of cool zones and warm belts varies from channel to channel suggesting complex vertical variations from the radiatively controlled upper troposphere to the convective mid troposphere we identify mid infrared signatures of jupiter s 5 m hotspots via simultaneous m n and q band observations which are interpreted as temperature and ammonia variations in the northern equatorial zone and on the edge of the north equatorial belt neb equatorial plumes enriched in nh3 gas are located south east of nh3 desiccated hotspots on the edge of the neb comparison of the hotspot locations in several channels across the 5 20 m range indicate that these anomalous regions tilt westward with altitude aerosols and ph3 are both enriched at the equator but are not co located with the nh3 plumes the equatorial temperature minimum and ph3 aerosol maxima have varied in amplitude over time possibly as a result of periodic equatorial brightenings and the fresh updrafts of disequilibrium material temperate mid latitudes display a correlation between mid ir aerosol opacity and the white albedo features in visible light i e zones we find hemispheric asymmetries in the distribution of tropospheric ph3 stratospheric hydrocarbons and the 2d wind field estimated via the thermal wind equation that suggest a differing efficiency of mechanical forcing e g vertical mixing and wave propagation between the two hemispheres that we argue is driven by dynamics rather than jupiter s small seasonal cycle jupiter s stratosphere is notably warmer at northern mid latitudes than in the south in both 2000 and 2014 although the latter can be largely attributed to strong thermal wave activity near 30 n that dominates the 2014 stratospheric maps and may be responsible for elevated c2h2 in the northern hemisphere a vertically variable pattern of temperature and windshear minima and maxima associated with jupiter s quasi quadrennial oscillation qqo is observed at the equator in both datasets although the contrasts were more subdued in 2014 large scale equator to pole gradients in ethane and acetylene are superimposed on top of the mid latitude mechanically driven maxima with c2h2 decreasing from equator to pole and c2h6 showing a polar enhancement consistent with a radiatively controlled circulation from low to high latitudes cold polar vortices beyond 60 latitude can be identified in the upper tropospheric and lower stratospheric temperature maps suggesting enhanced radiative cooling from polar aerosols finally compositional mapping of the great red spot confirms the local enhancements in ph3 and aerosols the north south asymmetry in nh3 gas and the presence of a warm southern periphery that have been noted by previous authors

jupiter new estimates of the mean zonal flow at the cloud level abstract previous estimates of the mean zonal flow on jupiter from voyager images by ingersoll et al a p ingersoll r f beebe j l mitchell g w garneau g m yagi and j p mueller 1981 j geophys res 86 8733 8743 and by limaye et al s s limaye h e revercomb l a sromovsky r j krauss v e suomi s a collins and c c avis 1982 j atmos sci 39 1413 1432 showed good agreement in the locations of the easterly and westerly jets but differed somewhat in magnitude recent measurements of the high speed jet located near 24 north plane topographic latitude by t maxworthy 1984 planet space sci 32 1053 1058 from high spatial and temporal resolution voyager images indicate that both ingersoll et al and limaye et al underestimated the magnitude of the jet by more than 30 40 msec 1 in an attempt to examine the differences in the magnitude of the jovian jets determined from voyager 1 and 2 images a new approach to determine the zonal mean east west component of motion was investigated the new technique based on simple digital pattern matching approach and applied on pairs of mapped images cylindrical mosaics yields a profile of the mean zonal component that reproduces the exact locations of the easterly and westerly jets between 60 latitude not only do the jet magnitudes but also the wings of the jets agree remarkably well from mosaic pair to pair further the latitudinal resolution is five midlatitudes to eight times equatorial greater than previous results results have been obtained for all of the voyager 1 and 2 cylindrical mosaics the correlation coefficient between voyager 1 and voyager 2 average mean zonal flow between 60 latitude determined from violet filter mosaics is 0 998 a slight latitude offset possibly due to navigation errors is detectable 0 2 latitude average in the voyager 1 data independent cloud motion measurements in two high resolution image pairs orange and violet acquired from voyager 1 cameras agree well with the average mean zonal flow for the fastest jovian jet at 23 8 n latitude comparison with maxworthy s 1984 results suggests longitudinal variations in cloud motions approaching about 20 msec 1 in particular the jet magnitude is about 163 7 rms msec 1 which compares well with 182 10 msec 1 reported by maxworthy there is excellent agreement in the location of the peak magnitude as well as its shape the time average voyager 2 mean zonal flow profile with latitude is presented in a table

the retrieval of cloud structure maps in the equatorial region of jupiter using a principal component analysis of galileo nims data abstract the cloud structure of the jovian atmosphere at pressures less than 2 bars has previously been estimated using near infrared observations such as those by both the solid state imager ssi and near infrared mapping spectrometer nims instruments on board the galileo spacecraft unfortunately complete near infrared spectra such as those measured by nims take a long time to be analyzed with multiple scattering radiative transfer models and thus it has until now been rather difficult to use these data to produce wide area cloud maps in this paper we show how principal component analysis may be employed to isolate a small number of empirical orthogonal functions eofs from spectra of jupiter made by galileo nims these eofs may be used to represent the variance of real nims spectra to a high degree of accuracy and with good noise and drop out discrimination because of this a small set of representative spectra may then be calculated using these eofs and input into a retrieval model that generates a table of fitted cloud profiles for each case this approach avoids the long times required for analyzing a large number of spectra with full multiple scattering radiative transfer models and allows us to represent the variability of the 3000 spectra contained in the observations of the north equatorial belt neb used in this study with only 75 representative spectra the cloud structures fitted to these representative spectra were interpolated for the spectra found at individual locations in the measured nims data set to produce maps of cloud opacity and mean particle size we find that the dominant opacity variation anticorrelated with 5 m brightness exists in the 1 2 bar pressure range the distribution of the cloud at 0 72 bars is mapped and found to be more zonally diffuse than the lower clouds we find at least one 2000 km sized deep convective cloud in the neb vertically extending to all the pressure levels that can be sensed by nims

role of organic matter in the proterozoic oklo natural fission reactors gabon africa of the sixteen known oklo and the bangombe natural fission reactors hydrothermally altered elastic sedimentary rocks that contain abundant uraninite and authigenic clay minerals reactors 1 to 6 at oklo contain only traces of organic matter but the others are rich in organic substances reactors 7 to 9 are the subjects of this study these organic rich reactors may serve as time tested analogues for anthropogenic nuclear waste containment strategies organic matter helped to concentrate quantities of uranium sufficient to initiate the nuclear chain reactions liquid bitumen was generated from organic matter by hydrothermal reactions during nuclear criticality the bitumen soon became a solid consisting of polycyclic aromatic hydrocarbons and an intimate mixture of cryptocrystalline graphite which enclosed and immobilized uraninite and the fission generated isotopes entrapped in uraninite this mechanism prevented major loss of uranium and fission products from the natural nuclear reactors for 1 2 b y 24 refs 4 figs

organic geochemical analysis of sedimentary organic matter associated with uranium abstract samples of sedimentary organic matter from several geologic environments and ages which are enriched in uranium 56 ppm to 12 have been characterized the three analytical techniqyes used to study the samples were rock eval pyrolysis pyrolysis gas chromatography mass spectrometry and solid state c 13 nuclear magnetic resonance nmr spectroscopy in samples with low uranium content the pyrolysis gas chromatography products contain oxygenated functional groups as hydroxyl and molecules with both aliphatic and aromatic carbon atoms these samples with low uranium content give measurable rock eval hydrocarbon and organic co 2 yields and c 13 nmr values of 30 aliphatic carbon in contrast uranium rich samples have few hydrocarbon pyrolysis products increased rock eval organic co 2 contents and 70 aromatic carbon contents from c 13 nmr the increase in aromaticity and decrease in hydrocarbon pyrolysis yield are related to the amount of uranium and the age of the uranium minerals which correspond to the degree of radiation damage the three analytical techniques give complementary results increase in rock eval organic co 2 yield correlates with uranium content for samples from the grants uranium region calculations show that the amount of organic co 2 corresponds to the quantity of uranium chemically reduced by the organic matter for the grants uranium region samples

the evolving flow of jupiter s white ovals and adjacent cyclones abstract we present results regarding the dynamical meteorology of jupiter s white ovals at different points in their evolution starting from the era with three white ovals fa bc and de galileo continuing to the post merger epoch with only one oval ba cassini and finally to oval ba s current reddened state new horizons we demonstrate that the dynamics of their flow have similarly evolved along with their appearance in the galileo epoch oval de had an elliptical shape with peak zonal wind speeds of 90 m s 1 in both its northern and southern peripheries during the post merger epoch oval ba s shape was more triangular and less elliptical than oval de in addition to widening in the north south direction its northern periphery was 20 m s 1 slower and its southern periphery was 20 m s 1 faster than oval de s flow during the galileo era finally in the new horizons era the reddened oval ba had evolved back to a classical elliptical form the northern periphery of oval ba increased in speed by 20 m s 1 from cassini to new horizons ending up at a speed nearly identical to that of the northern periphery of oval de during galileo however the peak speeds along the southern rim of the newly formed oval ba were consistently faster than the corresponding speeds in oval de and they increased still further between cassini and new horizons ending up at 140 150 m s 1 relative vorticity maps of oval ba reveal a cyclonic ring surrounding its outer periphery similar to the ring present around the great red spot the cyclonic ring around oval ba in 2007 appears to be moderately stronger than observed in 1997 and 2001 suggesting that this may be associated with the coloration of the vortex the modest strengthening of the winds in oval ba the appearance of red aerosols and the appearance of a turbulent cyclonic feature to oval ba s northwest create a strong resemblance with the great red spot from both a dynamical and morphological perspective in addition to the white ovals we also measure the winds within two compact cyclonic regions one in the galileo data set and one in the cassini data set in the images these cyclonic features appear turbulent and filamentary but our wind field reveals that the flow manifests as a coherent high speed collar surrounding relatively quiescent interiors our relative vorticity maps show that the vorticity likewise concentrates in a collar near the outermost periphery unlike the white ovals which have peak relative vorticity magnitudes near the center of the vortex the cyclones contain several localized bright regions consistent with the characteristics of thunderstorms identified in other studies although less studied than their anticyclonic cousins these cyclones may offer crucial insights into the planet s cloud level energetics and dynamical meteorology

stable isotope constraints on the role of graphite in the genesis of unconformity type uranium deposits the key lake unconformity type uranium deposit occurs in a shear zone where it intersects the unconformity between archean and aphebian gneisses and the overlying proterozoic athabasca group sandstones the roots of the key lake and many other unconformity type uranium deposits in the athabasca basin are close to gneisses rich in graphite and most deposits have small amounts of carbonaceous materials bitumen and hydrocarbon buttons within and around altered basement and sandstone ore zones in many athabasca uranium deposits hydrothermal fluids have destroyed graphite disseminated in the strongly altered gneisses in the vicinity of the deposits prompting some to suggest that graphite was converted to ch4 which reduced and precipitated the uranium and partially condensed to form bitumen the 13c values of graphite collected from unaltered and altered gneisses around the key lake deposit have a limited range 25 5 and are not a function of distance from the mineralization or the intensity of alter

galileo images of lightning on jupiter in october and november of 1997 the galileo solid state imager ssi detected lightning from 26 storms on the night side of jupiter more than half the surface area of the planet was surveyed the data include images of lightning against moonlit clouds illuminated by light from io and images of the same storm on the day and night sides the spatial resolution ranged from 23 to 134 km per pixel while the storms ranged in size up to 1500 km most storms were imaged more than once and they typically exhibit many flashes per minute the storms occur only in areas of cyclonic shear and near the centers of westward jets latitudes near 50 in both hemispheres are particularly active although the northern hemisphere has more lightning overall the greatest optical energy observed in a single flash was 1 6 10 10 j which is several times larger than terrestrial superbolts the average optical power per unit area is 3 10 7 w m 2 which is close to the terrestrial value the limited color information is consistent with line and continuum emission from atomic hydrogen and helium the intensity profiles of resolved lightning strikes are bell shaped with the half width at half maximum ranging from 45 to 80 km we used these widths to infer the depth of the strikes assuming that the appearance of each is the result of light scattering from a point source below the cloudtops we conclude that lightning must be occurring within or below the jovian water cloud the occurrence of lightning in regions of cyclonic shear has important implications for the dynamics of jupiter s atmosphere

galileo imaging of jupiter s atmosphere the great red spot equatorial region and white ovals during the first six orbits of the galileo spacecraft s prime mission the solid state imaging ssi system acquired multispectral image mosaics of jupiter s great red spot an equatorial belt zone boundary a 5 m hot spot similar to the galileo probe entry site and two of the classic white ovals we present mosaics of each region approximating their appearance at visible wavelengths and showing cloud height and opacity variations the local wind field is derived by tracking cloud motions between multiple observations of each region with time separations of roughly 1 and 10 hr vertical cloud structure is derived in a companion paper by banfieldet al icarus135 230 250 galileo s brief high resolution observations complement earth based and voyager studies and offer local meteorological context for the galileo probe results our results show that the dynamics of the zonal jets and large vortices have changed little since voyager with a few exceptions we detect a cyclonic current within the center of the predominantly anticyclonic great red spot the zonal velocity difference between 0 s and 6 s has increased by 20 m sec 1 we measure a strong northeast flow approaching the hot spot this flow indicates either massive horizontal convergence or the presence of a large anticyclonic vortex southeast of the hot spot the current compact arrangement of two white ovals and a cyclonic structure greatly perturbs the zonal jets in that region

prevalent lightning sferics at 600 megahertz near jupiter s poles lightning has been detected on jupiter by all visiting spacecraft through night side optical imaging and whistler lightning generated radio waves signatures1 6 jovian lightning is thought to be generated in the mixed phase liquid ice region of convective water clouds through a charge separation process between condensed liquid water and water ice particles similar to that of terrestrial cloud to cloud lightning7 9 unlike terrestrial lightning which emits broadly over the radio spectrum up to gigahertz frequencies10 11 lightning on jupiter has been detected only at kilohertz frequencies despite a search for signals in the megahertz range 12 strong ionospheric attenuation or a lightning discharge much slower than that on earth have been suggested as possible explanations for this discrepancy13 14 here we report observations of jovian lightning sferics broadband electromagnetic impulses at 600 megahertz from the microwave radiometer 15 onboard the juno spacecraft these detections imply that jovian lightning discharges are not distinct from terrestrial lightning as previously thought in the first eight orbits of juno we detected 377 lightning sferics from pole to pole we found lightning to be prevalent in the polar regions absent near the equator and most frequent in the northern hemisphere at latitudes higher than 40 degrees north because the distribution of lightning is a proxy for moist convective activity which is thought to be an important source of outward energy transport from the interior of the planet16 17 increased convection towards the poles could indicate an outward internal heat flux that is preferentially weighted towards the poles9 16 18 the distribution of moist convection is important for understanding the composition general circulation and energy transport on jupiter observations of broadband emission from lightning on jupiter at 600 megahertz show a lightning discharge mechanism similar to that of terrestrial lightning and indicate increased moist convection near jupiter s poles

jupiter s equatorial plumes and hot spots spectral mapping from gemini texes and juno mwr we present multi wavelength measurements of the thermal chemical and cloud contrasts associated with the visibly dark formations also known as 5 m hot spots and intervening bright plumes on the boundary between jupiter s equatorial zone ez and north equatorial belt neb observations made by the texes 5 20 m spectrometer at the gemini north telescope in march 2017 reveal the upper tropospheric properties of 12 hot spots which are directly compared to measurements by juno using the microwave radiometer mwr jiram at 5 m and juno cam visible images mwr and thermal infrared spectroscopic results are consistent near 0 7 bar mid infrared derived aerosol opacity is consistent with that inferred from visible albedo and 5 m opacity maps aerosol contrasts the defining characteristics of the cloudy plumes and aerosol depleted hot spots are not a good proxy for microwave brightness the hot spots are neither uniformly warmer nor ammonia depleted compared to their surroundings at p 10 bars suggesting that the hot spot plume wave is a relatively shallow feature plain language summary to date our only direct measurement of jupiter s gaseous composition came from the descent of the galileo probe in 1995 however the results from galileo appeared to be biased due to the unusual meteorological conditions of its entry location a dark cloud free region just north of the equator known as a hot spot one of the aims of nasa s juno mission was to place the findings of the galileo probe into broader con text which requires a detailed characterisation of these equatorial hot spots and their neighbouring plumes we combine a data from juno microwave observations sounding conditions below the clouds and visible infrared observations revealing variations in cloud opacity with b observations from amateur observers to track the hot spots over time and c observations from the texes infrared spectrometer mounted on the gemini north telescope the latter provides the highest resolution thermal maps of jupiter s tropics ever obtained and reveals contrasts within and between the individual hot spots and plumes we find that the hot spots are distinguishable from their surroundings for relatively shallow pressures but that the deep measurements from juno and galileo are probably more representative of jupiter s north equatorial belt than previously thought

modeling jupiter s cloud bands and decks 2 distribution and motion of condensates abstract a simple jovian cloud scheme has been developed for the oxford planetary unified model system opus nh 3 ice nh 4 sh solid h 2 o ice and h 2 o liquid clouds have been modeled in southern hemisphere limited area simulations of jupiter we found that either three or four of the condensates existed in the model for a deep atmospheric water abundance close to solar composition an nh 3 ice deck above 0 7 bar an nh 4 sh solid deck above 2 5 bar and a h 2 o liquid deck with a base at about 7 5 bar and frozen cloud tops formed if a depleted deep water abundance is assumed however a very compact cloud structure develops where an h 2 o ice cloud forms by direct sublimation above 3 bar the condensates constitute good tracers of atmospheric motion and we have confirmed that zonal velocities determined from manual feature tracking in the modeled cloud layers agree reasonably well with the modeled zonal velocities dense and elevated clouds form over latitudes with strong atmospheric upwelling and depleted clouds exist over areas with strong downwelling in the nh 3 ice deck this leads to elevated cloud bands over the zones in the domain and thin clouds over the belts which is consistent with the observationally deduced distribution due to changes in the vertical velocity pattern in the deeper atmosphere the nh 4 sh solid and water cloud decks are more uniform this modeled cloud structure thus includes the possibility of more frequent water cloud observations in belts as this deeper deck could be more easily detected under areas with thin nh 3 ice clouds large scale vortices appeared spontaneously in the model and were characterized by elevated nh 3 ice clouds as expected from observations these eddies leave the most discernible imprint on the lighter condensate particles of the uppermost layer

cassini imaging of jupiter s atmosphere satellites and rings the cassini imaging science subsystem acquired about 26 000 images of the jupiter system as the spacecraft encountered the giant planet en route to saturn we report findings on jupiter s zonal winds convective storms low latitude upper troposphere polar stratosphere and northern aurora we also describe previously unseen emissions arising from io and europa in eclipse a giant volcanic plume over io s north pole disk resolved images of the satellite himalia circumstantial evidence for a causal relation between the satellites metis and adrastea and the main jovian ring and information on the nature of the ring particles

petrography and paragenesis of organic matter associated with the natural fission reactors at oklo republic of gabon a preliminary report sixteen known uranium rich pockets in the sediment hosted uranium ore deposits in the oklo area became nuclear fission reactors 1968 50 ma ago and operated as such for up to 1 ma nuclear criticality was caused by unique and fortuitous geological environments and events these included the localized high concentrations of uranium in small pockets in the ore bodies the fact that the relative abundance of the fissile 235u isotope was five times greater in uranium 2 ga ago than present the presence of water which acted as a moderator in the natural reactors and the absence of neutron poisons which are elements that can prevent nuclear chain reactions organic matter is present in all of the oklo natural reactors but it is abundant only in reactors 7 to 16 organic matter has been studied in natural reactors 7 to 9 and at locations at various distances from these reactors bitumen in the oklo reactors is the predominant organic phase it is now solid bitumen containing dispersed cryptocrystalline graphite in crystal domains smaller than optical microscopic size its immediate precursor was liquid bitumen generated from syngenetic kerogen in organic rich sedimentary rocks in the francevillian basin of gabon and in the natural reactors themselves by hydrous reaction mechanisms prior to during and after nuclear criticality a preliminary paragenesis of organic matter at oklo may be defined through the following sequence of events a protokerogen and kerogen evolve from abundant cyanobacteria in the tidal and deltaic sediments in the basal fa formation of the francevillian series during sedimentation and burial respectively b during subsequent subsidence of the basin the first generation of bitumen and petroleum occurred c during uplift the sedimentary strata were fractured and bitumen and petroleum migrated through fractures following this oxidizing aqueous solutions carrying uranyl ions migrated through the highly fractured rocks met and were reduced by organic matter and precipitated pitchblende or uraninite at the present sites of the oklo uranium ore deposits and natural reactors the natural reactors reached nuclear criticality they were heated and produced the second generation of bitumen through hydrous reactions from the by now solid first generation bitumen and remaining kerogen finally hydrothermal effects associated with the dolerite dike swarm intrusion 750 150 ma ago produced yet another localized generation of liquid bitumen from solid organic matter possibly other bitumen generations also occurred during and following this time interval the organic matter in the natural reactors soon became a solid and was able to prevent the loss of uraninite grains enclosed in it these uraninite grains trapped and then immobilized fission products until and to an extent even after a major tectonic igneous event the intrusion of the dolerite dike swarm

zonal jets as transport barriers in planetary atmospheres abstract the connection between transport barriers and potential vorticity pv barriers in pv conserving flows is investigated with a focus on zonal jets in planetary atmospheres a perturbed pv staircase model is used to illustrate important concepts this flow consists of a sequence of narrow eastward and broad westward zonal jets with a staircase pv structure the pv steps are at the latitudes of the cores of the eastward jets numerically simulated solutions to the quasigeostrophic pv conservation equation in a perturbed pv staircase flow are presented these simulations reveal that both eastward and westward zonal jets serve as robust meridional transport barriers the surprise is that westward jets across which the background pv gradient vanishes serve as robust transport barriers a theoretical explanation of the underlying barrier mechanism is provided it is argued that transport barriers near the cores of westward zonal jets across which the background pv gradient is small are found in jupi

refining paleoaltimetry reconstructions of the sierra nevada california using air parcel trajectories stable isotope paleoaltimetry studies often implicitly assume that atmospheric flow interactions with topography can be simply modeled as a rayleigh distillation process in which air parcels consistently ascend topographic barriers we present a modern a d 1979 2010 air parcel trajectory analysis using the hybrid single particle lagrangian integrated trajectory hysplit model that shows that this fundamental assumption is often violated in the sierra nevada region of the western united states observed trajectory patterns and scaling calculations indicate that windward orographic blocking frequently occurs when trajectories encounter high elevations 2 5 km in the central and southern sierra nevada as a result trajectories reaching the sierran lee commonly travel around rather than over the highest range elevations redirection effects are particularly pronounced at leeward sites distal 150 km to the sierran crest but are also evident in trajectory patterns in the northern sierra nevada this trajectory analysis improves the interpretability of regional meteoric water and proxy isotopic records and has particular relevance to stable isotope based reconstructions of sierran paleoelevations specifically stable isotope methods alone provide only limited insight into the elevation history of the sierra nevada and are likely insufficient to resolve proposed late cenozoic elevation gains on the order of 1 2 km that may have raised the sierra to its modern elevations

a model for large scale convective storms in jupiter 1 large scale convective storms are a common phenomenon in jupiter s atmosphere they are apparent in ground based and spacecraft images and may strongly affect the dynamics of the global atmosphere as well as the energy transport in the meteorological layer in this paper we analyze the outburst of a large convective storm system core 5000 km in the south equatorial belt seb that was observed at high spatial and temporal resolution by the voyager 1 spacecraft in 1979 we use a two dimensional 2 d model to study the interaction between cloud material brought up by moist convection and the environmental wind aided by previous 3 d models of jovian storms we can draw several qualitative and quantitative conclusions the evolution of this storm can be characterized by three phases 1 onset of the perturbation well reproduced by the growth of a single cell storm 2 an expanding phase in which the number of convective cells increases to 200 with updraft velocities limited to 50 m s and 3 a relatively sudden suppression of the convective activity leading to the disruption of large structures by the environmental wind furthermore we interpret the observations of the inner bright core as a well defined anticyclonic vortex with darker cloud material preferentially left southwest of the system finally we show that 1016 w are released by such a storm over its life cycle of 12 days and that the direct formation of a large scale anticyclonic vortex after the moist convective source has been removed is prevented by the environmental wind shear

mineral chemistry and oxygen isotopic analyses of uraninite pitchblende and uranium alteration minerals from the cigar lake deposit saskatchewan canada abstract the cigar lake unconformity type u deposit is one of the largest and highest grade u deposits in the proterozoic athabasca basin northern saskatchewan canada cigar lake has recently been the focus of an international 3 a collaborative program in which this u deposit was studied as a natural analogue for a spent nuclear fuel repository the deposit is located near the eastern margin of the athabasca basin 430 m below the surface at the intersection between hudsonian age faults and the unconformity between athabasca group sandstones and aphebian metasediments three stages of u mineralization have been identified based on cross cutting relationships and textures observed in thin section and back scattered electron bse images o isotope data and chemical compositions all stages of u mineralization have been variably altered to ca rich u hydrate minerals or uranyl oxide hydrate minerals and coffinite u pb chemical ages of the 3 stages of u mineralization from cigar lake coincide with the 3 major fluid events that precipitated clay and silicate minerals at 1500 ma 950 ma and 300 ma throughout the entire athabasca basin stage 1 and 2 uraninite and pitchblende have the lowest 18o values that range from 30 1 to 15 2 whereas stage 3 uraninite has 18o values ranging from 10 0 to 3 4 uranyl oxide hydrate minerals have 18o values that range from 11 3 to 8 2 whereas uranyl minerals have much higher 18o values based on u pb chemical ages 18o values and petrographic relationships of u alteration minerals associated with primary u mineralization the cigar lake u ore is similar to u ore from other unconformity type u deposits in the athabasca basin therefore the cigar lake ore deposit although surrounded by clay and sandstone barriers has been effected by the same fluid events that have altered other unconformity type u deposits in the athabasca basin the 3 stages of ore formation and associated alteration minerals permit the detailed study of fluids responsible for u deposition and alteration this information provides the necessary context for the evaluation of the cigar lake deposit as a natural analogue for the disposal of spent nuclear fuel in underground vaults in rocks of the canadian shield

moist convection as an energy source for the large scale motions in jupiter s atmosphere jupiter s dominant large scale weather patterns dimensions 10 000 km are zonal jets and long lived ovals the jets have been flowing east and west at constant speeds of up to 180 m s 1 for over 100 years these jets receive energy from small scale eddies which pump eastward momentum into the eastward jets and westward momentum into the westward jets this momentum transfer was predicted by numerical models before it was observed on jupiter the large ovals roll between the jets in an anticyclonic direction clockwise in the northern hemisphere and counterclockwise in the southern hemisphere where they regularly assimilate small anticyclonic eddies but from where the eddies receive their energy has been an open question here we argue that the eddies which ultimately drive both the jets and the ovals receive their energy from moist convection this hypothesis is consistent with observations of jovian lightning which is an indicator of moist convection it also explains the anticyclonic rotation and poleward drift of the eddies and suggests patterns of upwelling and downwelling that resemble the patterns of large scale axisymmetric overturning in the earth s atmosphere

convective growth rates of equatorial features in the jovian atmosphere the first results of measurements of divergence and vertical velocity of cloud features in the atmosphere of jupiter are presented from analyses of voyager images performed using the interactive planetary imaging processing system at university college london active equatorial plumes are found to have typical divergences of 1 2 10 5s 1 and vertical velocities of 20 40 cm s 1 during the observational periods examined these plumes are considerably more active than the bright albedo features in the turbulent regions of the jovian north and south equatorial belts

jupiter s unearthly jets a new turbulent model exhibiting statistical steadiness without large scale dissipation abstracta longstanding mystery about jupiter has been the straightness and steadiness of its weather layer jets quite unlike terrestrial strong jets with their characteristic unsteadiness and long wavelength meandering the problem is addressed in two steps the first is to take seriously the classic dowling ingersoll di 1 layer scenario and its supporting observational evidence pointing toward deep massive zonally symmetric zonal jets in the underlying dry convective layer the second is to improve the realism of the model stochastic forcing used to represent the effects of jupiter s moist convection as far as possible within the 1 layer dynamics of the di scenario the real moist convection should be strongest in the belts where the interface to the deep flow is highest and coldest and should generate cyclones as well as anticyclones with the anticyclones systematically stronger the new model forcing reflects these insights also it acts quasi frictionally on large scales to produce statisti

uranium bearing stratiform organic matter in paleoplacers of the lower huronian supergroup elliot lake blind river region canada the elliot lake blind river ontario paleoplacer deposits in the basal matineda formation lowermost member of the 2 25 2 45 ga old huronian supergroup contain organic matter chemically consistent with kerogen this substance is also referred to as thucholite uranium ores and some gold occur here and these minerals may be in close association with the kerogen two uraniferous and auriferous stratiform kerogens obtained from the denison mines limited s denison mine and rio algom limited s stanleigh mine have been analyzed by combined high vacuum pyrolysis gas chromatography mass spectrometry and by neutron activation the reflectances of these samples have also been determined related samples containing dispersed kerogen have been examined by backscattered scanning electron microscopy the polymer like matrix of the two stratiform kerogens consists of aromatic alkyl aromatic hydrocarbon and sulphur moieties and contains 20 and 32 uranium with gold abundances in the parts per billion range

characterization of graphite alteration and bitumen genesis in the cigar lake deposit saskatchewan canada bitumens collected in the east zone of the cigar lake deposit have been analyzed by c 13 nuclear magnetic resonance pyrolysis gas chromatography rock eval and c h and 0 methods carbon and hydrogen isotopic compositions and uranium contents have been determined results indicate that the bitumens consist mainly of aromatic structures f a almost equal to 60 and have undergone a late oxidation process similarities in carbon isotopic composition 27 5 part per thousand deltac 13 28 2 parts per thousand between barren bitumens u 300 ppm and graphite collected in the basement gneisses as well as evidence for progressive disorganization of graphite along a basement profile suggest a genetic relationship between graphite and bitumens from the mineralized areas the presence of amorphous carbon in pit structures inside graphite flakes close to the unconformity supports this assessment significant differences in geochemical and isotopic characteristics of the cigar lake barren bitumens and the cluff lake mineralized bitumens suggest that there are two possible mechanisms for their formation barren c enriched bitumens could have formed directly by hydrogenation of amorphous carbon whereas mineralized isotopically light bitumens from cluff lake deltac 13 almost equal to 48 parts per thousand may result from the polymerization of light hydrocarbons around uraninite grains

geochronology and genesis of the bong uranium deposit thelon basin nunavut canada the thelon basin nunavut shares many similarities with the uranium producing athabasca basin saskatchewan however the uranium deposits associated with the thelon basin are still poorly understood the kiggavik project area areva resources canada is located near the northeastern terminus of the thelon basin and comprises multiple uranium deposits hosted exclusively in basement rocks the bong deposit is hosted dominantly by neoarchean metagraywacke of the woodburn lake group a five phase metallogenetic model is proposed for the bong deposit with three stages of uraninite identified the premineralization phase is characterized by host rock silicification mineralization is separated into three main stages stage 1 uraninite u1 ca 1500 ma is preserved in highly fractured and altered disseminated grains that are overgrown by later stages of uraninite stage 2 uraninite u2 ca 1100 ma forms veinlets parallel to d 1 foliation and coats and fills fractures in organic matter nodules and blebs stage 2 uraninite is associated with pervasive illite that formed from 190 c fluids 18 o 6 4 2 h 97 which remobilized much of stage 1 uraninite and completely overprinted stage 1 alteration at 1000 ma an oxidizing fluid deposited uraninite along redox fronts u3 while altering and remobilizing stage 1 and 2 uraninite post uranium oxide minerals include drusy quartz calcite and illite accompanied by uranyl phases e g uranophane ca u

characterization of insoluble organic matter from the lower proterozoic huronian supergroup elliot lake ontario abstract elliot lake organic matter falls into two main groups 1 stratiform kerogens with reflectance from 2 63 to 7 31 ro max exhibit a high level of aromaticity and low atomic h c ratios 0 41 0 60 2 less aromatic disseminated globules most resembling solid bitumen are of lower maturity with ro max from 0 72 to 1 32 and atomic h c ratios 0 71 0 81 stratiform kerogens originated from cyanobacteria have 13c values from 15 to 25 one exception with 13c 31 8 may have originated from methanogenic source biota thus two genetically distinct populations of kerogen are tentatively recognized in elliot lake metasediments globular bitumens remobilized by hydrous pyrolysis from kerogen exhibit 13c values ranging from 25 tp 33 0 the overall isotopic bimodality among elliot lake organic material is explained by analogy to petroleum generation from particulate kerogen that matured under conditions of catagenesis to metagenesis and was subjected to radiation over a long time barium u th au pt pd and ree contents of elliot lake stratiform kerogen greatly exceed of average black shales except for as pt pd and au all metals ti v cr mn fe co ni zn se rb sr ag sb cs ba hf ta w hg th and u are more concentrated in stratiform kerogens than in the derivative bitumen this signals a significant role for a low temperature transfer of noble metals to migrating bitumen

geochemistry of uraniferous bitumen in the southwest athabasca basin saskatchewan canada the sediment hosted unconformity type southwest athabasca uranium mineralization in northern saskatchewan canada contains uraniferous bitumen as observed elsewhere in the athabasca basin uraninite is present either as micron sized grains dispersed in bitumen uraniferous bitumen or as larger grains situated in the pore space between bitumen globules the spatial and textural relationships between uraninite and bitumen suggest that they were co precipitated la icp ms u pb dating of uraniferous bitumen yielded an age of 1575 53 ma similar to that of other unconformity type uranium mineralization in the athabasca basin indicating that the bitumen was formed early in the history of the basin nitrogen carbon and sulfur isotope analyses of uraniferous bitumen indicate that its source material was probably kerogen produced by cyanobacteria in a clastic environment

formation of the enigmatic matoush uranium deposit in the paleoprotozoic otish basin quebec canada the matoush uranium deposit is situated in the paleoproterozoic otish basin northern quebec canada and is hosted by the indicator formation sandstones its sheet like ore bodies are closely associated with the steeply dipping matoush fracture which hosts mafic dykes and minor quartz feldspar tourmaline pegmatites regional diagenesis involving oxidizing basinal fluids 2h 15 18o 8 produced mostly illite and possibly leached u from accessory phases in the indicator formation sandstones the bimodal matoush dyke intruded the indicator formation along the matoush fracture and the related metasomatism produced cr rich dravite and muscovite in both the dyke and the proximal sandstones uraninite formed when u6 in the basinal brine was reduced to u4 in contact with the mafic dyke and by fe2 in cr dravite and cr muscovite and precipitated together with eskolaite and hematite because of its unique characteristics the matoush deposit cannot be easily classified within the generally accepted classification of uranium deposits two of its main characteristics unusual reduction mechanism structural control do not correspond to the sandstone hosted group of deposits unconformity type tabular roll front in spite of uranium being derived from the otish group sandstones

jupiter s cloud structure from galileo imaging data the vertical structure of aerosols on jupiter is inferred from data obtained by the nasa galileo solid state imaging system during the first six orbits of the spacecraft images at 889 nm a strong methane band 727 nm a weaker methane band and 756 nm continuum taken at a variety of lighting and viewing angles are used the images are displayed and described in the companion paper by vasavada et al 1998 icarus 135 265 275 conservative scattering cloud particles with laterally uniform single scattering properties are assumed in the analysis and are shown to be consistent with the data at these wavelengths particles are bright and the darkest locations on jupiter correspond to the smallest optical thickness of aerosols optical depths and vertical positions of aerosol layers vary from place to place and are the retrieved quantities in the analysis only mid and low latitudes are sampled in this data set a stratospheric haze with an optical depth of roughly a tenth and an upper tropospheric haze with an optical depth of 2 to 6 exist over all regions both are consistent with previous conclusions based on data of lower spatial resolution e g west et al 1986 icarus 65 161 217 the new data show that these layers contain little lateral structure on scales smaller than the planetary jets on scales of the jets and ovals the top and bottom of the upper tropospheric haze vary in elevation the concentration of particles optical depth per pressure interval varies less than does the total optical depth near the base of the upper tropospheric haze is a third cloud component usually at pressure p 750 200 mb which is less than a scale height in geometric thickness its optical depth varies from zero to about 20 on regional scales and often varies by 50 on scales of a few tens of kilometers optical depth variations in this cloud are the principal cause of the features in jupiter s atmosphere seen at red and longer wavelengths it is probably composed of ammonia the expected nh 4sh cloud has not been identified in this work perhaps because it exists only at locations where it is concealed beneath higher clouds our retrievals also cannot rule out a pervasive deep haze without small scale structure finally in one region northwest of the great red spot a deeper cloud is identified parts of it lie at a pressure greater than four bars it is associated with a rapidly changing storm system with optical depth of several tens or more and a range of cloud heights between p 4 bars to p 400 mb it is probably composed of water

moist convection and the 2010 2011 revival of jupiter s south equatorial belt fletcher was supported by a royal society research fellowship at the university of leicester giles was supported by a royal society research grant at the university of oxford the uk authors acknowledge the support of the science and technology facilities council stfc a portion of this work was performed by orton and payne at the jet propulsion laboratory california institute of technology under a contract with nasa this research used the alice high performance computing facility at the university of leicester we are extremely grateful for the combined efforts of the numerous amateur observers including those listed in the figure captions for sharing their data and for the jupos software developed by grischa hahn and hans jorg mettig to reproject the visible light data this investigation was partially based on thermal infrared observations acquired at i the eso very large telescope paranal ut3 melipal observatory using directors discretionary time program id 286 c 5009 and regular service time program id 087 c 0024 ii the subaru telescope which is 27 operated by the national astronomical observatory of japan program id o11154 iii nasa s infrared telescope facility which is operated by the university of hawaii under contract nnh14ck55b with the national aeronautics and space administration program ids 2010b010 2011a010 2011b027 and iv observations obtained at the gemini observatory program ids gn 2010b dd 3 gs 2010b q 8 and gs 2011aq 11 which is operated by the association of universities for research in astronomy inc under a cooperative agreement with the nsf on behalf of the gemini partnership the national science foundation united states the national research council canada conicyt chile ministerio de ciencia tecnolog ia e innovacion productiva argentina and ministerio da ci encia tecnologia e inovac ao brazil we wish to recognise and acknowledge the very significant cultural role and reverence that the summit of mauna kea has always had within the indigenous hawaiian community we are most fortunate to have the opportunity to conduct observations from this mountain

dynamical implications of jupiter s tropospheric ammonia abundance abstract groundbased radio observations indicate that jupiter s ammonia is globally depleted from 0 6 bars to at least 4 6 bars relative to the deep abundance of 3 times solar a fact that has so far defied explanation the observations also indicate that i the depletion is greater in belts than zones and ii the greatest depletion occurs within jupiter s local 5 m hot spots which have recently been detected at radio wavelengths here we first show that both the global depletion and its belt zone variation can be explained by a simple model for the interaction of moist convection with jupiter s cloud layer circulation if the global depletion is dynamical in origin then important endmember models for the belt zone circulation can be ruled out next we show that the radio observations of jupiter s 5 m hot spots imply that the equatorial wave inferred to cause hot spots induces vertical parcel oscillation of a factor of 2 in pressure near the 2 bar level which places important constraints on hot spot dynamics finally using spatially resolved radio maps we demonstrate that low latitude features exceeding 4000 km diameter such as the equatorial plumes and large vortices are also depleted in ammonia from 0 6 bars to at least 2 bars relative to the deep abundance of 3 times solar if any low latitude features exist that contain 3 times solar ammonia up to the 0 6 bar ammonia condensation level they must have diameters less than 4000 km

from evaporated seawater to uranium mineralizing brines isotopic and trace element study of quartz dolomite veins in the athabasca system abstract stable isotope o h c radiogenic isotope sr nd and trace element analyses have been applied to quartz dolomite veins and their uranium u bearing fluid inclusions associated with proterozoic unconformity related uo 2 uraninite ores in the athabasca basin canada in order to trace the evolution of pristine evaporated seawater towards u mineralizing brines during their migration through sediments and basement rocks fluid inclusion data show that quartz and dolomite have precipitated from brines of comparable chemistry excepted for relatively small amounts of co 2 found in dolomite hosted fluid inclusions however 18 o values of quartz veins 18 o 11 to 18 and dolomite veins 18 o 13 to 24 clearly indicate isotopic disequilibrium between quartz and dolomite hence it is inferred that this isotopic disequilibrium primarily reflects a decrease in temperature between the quartz stage 180 c and the dolomite stage 120 c the 13 c values of co 2 dissolved in dolomite hosted fluid inclusions 13 c 30 to 4 and the 13 c values of dolomite 13 c 23 5 to 3 5 indicate that the co 2 dissolved in the mineralizing brines originated from brine graphite interactions in the basement the resulting slight increase in the fluid partial pressure of co 2 p co 2 may have triggered dolomite precipitation instead of quartz 18 o values of quartz veins and previously published 18 o values of the main alteration minerals around the u ores illite chlorite and tourmaline show that quartz and alteration minerals were isotopically equilibrated with the same fluid at 180 c the ree concentrations in dolomite produce paas normalized patterns that show some similarities with that of uo 2 and are clearly distinct from that of the other main ree bearing minerals in these environments monazite zircon and aluminum phosphate sulfate aps minerals the radiogenic isotope compositions of dolomite 87 sr 86 sr i 0 7053 to 0 7161 and e nd t 8 8 to 20 3 differ from one deposit to another reflecting both heterogeneity in the basement geology and variable preservation of the original composition of brines the previously published 87 sr 86 sr i and e nd t values of uo 2 compare with the most evolved dolomites i e dolomites precipitated from brines that exchanged the most with the basement this reinforces a close genetic link between dolomites and uo 2 deposition and implies that uo 2 deposition occurred in a cooling system during the transition from quartz to dolomite formation the 18 o and d values of the mineralizing brines 18 o 1 to 8 and d 150 to 50 are considerably shifted from that of their theoretical original values acquired during evaporation of seawater 18 o 3 and d 40 the positive 18 o shift is explained by protracted fluid rock interaction within the basin and basement rocks the negative d shift is attributed to incomplete mixing between the u mineralizing brines and low d water this low d water was likely produced during the abiogenic synthesis of bitumen by fisher tropsch like reactions involving co 2 derived from brine graphite interaction in the basement and radiolytic h 2 the resulting low d brines have been equilibrated with alteration minerals this may explain why some alteration minerals yield anomalously low d values whose significance has long been debated

atmospheric waves and dynamics beneath jupiter s clouds from radio wavelength observations abstract we observed jupiter at wavelengths near 2 cm with the karl g jansky very large array vla in february 2015 these frequencies are mostly sensitive to variations in ammonia abundance and probe between 0 5 2 0 bars of pressure in jupiter s atmosphere within and below the visible cloud deck which has its base near 0 7 bars the resultant observed data were projected into a cylindrical map of the planet with spatial resolution of 1500 km at the equator we have examined the data for atmospheric waves and observed a prominent bright belt of radio hotspot features near 10 n likely connected to the same equatorial wave associated with the 5 m hotspots we conducted a passive tracer power spectral wave analysis for the entire map and latitude regions corresponding to eastward and westward jets and compare our results to previous studies the power spectra analysis revealed that the atmosphere sampled in our observation excluding the neb region is in a 2 d turbulent regime and its dynamics are predominately governed by the shallow water equations the great red spot grs is also very prominent and has a noticeable meridional asymmetry and we compare it and nearby storms with optical images we find that the meridional radio profile has a global north south hemisphere distinction and find correlations of it to optical intensity banding and to shear zones of the zonal wind profile over select regions of latitude amateur optical images taken before and after our observation complemented the radio wavelength map to investigate dynamics of the equatorial region in jupiter s atmosphere we find that two radio hotspots at 2 cm are well correlated with optical plumes in the neb additionally revealing they are not the same 5 m hotspot features correlated with optical dark patches between adjacent plumes this analysis exploits the vla s upgraded sensitivity and explores the opportunities now possible when studying gas giants especially atmospheric dynamics of layers beneath upper level clouds