oxygen isotope evidence for extensive crustal contamination in the okenyenya igneous complex namibia abstract oxygen isotope data are presented for silicate minerals separated from a variety of rock types from the 130 ma okenyenya igneous complex of northwestern namibia these rock types include a tholeiitic suite ranging from olivine gabbro to quartz monzodiorite and syenite and an alkaline suite including gabbro syenite nepheline syenite and essexite in general the difference in 18 o values between coexisting feldspar pyroxene and biotite are consistent with equilibrium at high temperatures and preclude significant interaction with magmatic or external fluids the 18 o values of pyroxene can be used to model magmatic processes and show a systematic increase from 7 1 9 0 along a transect through a tholeiitic olivine gabbro quartz monzodioritic body corresponding to a systematic decrease in mg pyroxene 18 o values also show a strong correlation with initial strontium and neodymium isotope ratios with the alkaline suite having lower 18 o values lower initial strontium isotope ratios and higher initial neodymium isotope ratios than the tholeiitic suite simple oxygen mass balance calculations suggest that the extremes of isotope composition resulted from at least 60 contamination by material of similar isotope composition to the nearby southern etendeka quartz latites assimilation crystal fractionation models of oxygen strontium and neodymium isotope data suggest that the rate of assimilation was high and may have approached simple mixing the contaminated tholeiitic olivine gabbro quartz monzodioritic body was the earliest to crystallize in the complex and this was followed by relatively uncontaminated silica undersaturated magmas

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

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

oxygen isotope constraints on the petrogenesis of volcanic arc magmas from martinique lesser antilles abstract volcanic rocks from the island of martinique in the lesser antilles island arc are highly diverse isotopically values of 18o smow in lavas erupted over the last 5 ma from five stratigraphically discrete and geochemically distinct volcanic centers are morne jacob 7 5to 7 9 pitons du carbet 8 0to 8 9 diamant 6 3to 7 4 piton mt conil 7 2to 7 3 andmt pelee 6 5to 7 4 13 of the 27 samples have been corrected for variable amounts of secondary alteration and low temperature hydration the least18o rich andesites on martinique have 18o values similar to those of the northern lesser antilles 18o 6 0 to 7 3 and other intra oceanic arcs like the marianas 18o 5 5 to 6 8 o isotope ratios are compositionally dependent correlations between 18o and radiogenic isotope ratios 87sr 86sr 143nd 144nd 206pb 204pb and indices of fractionation show that modification of isotopic compositions occurred during magmatic differentiation rather than at source a two stage model is proposed for the origin and differentiation of magmas on martinique primary basaltic melts which are broadly similar in composition to primitive island arc magmas elsewhere e g marianas aleutians south sandwich islands are generated from the subduction modified asthenospheric mantle wedge these magmas ascend into the arc crust and differentiate on martinique crystal fractionation is accompanied by contamination with isotopically distinct crust including a component of terrigenous sediments thus subduction zone processes at the lesser antilles and other island arcs are similar involving only a small albeit significant isotopically volumetric contribution from subducted sediment

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 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

18o 16o and chemical relationships in k rich volcanic rocks from australia east africa antarctica and san venanzo cupaello italy 18o 16o analyses were made on a set of leucite bearing igneous rocks from a variety of localities around the world the samples chosen for study all have relatively primitive characteristics such as low sio2 contents 42 52 wt whole rock 18o values from the 10 15 m y old australian leucitites range from 7 1 to 11 0 however none of these values represents the original 18o of the erupted lava as every sample has undergone some subsolidus18o enrichment the 18o values of the primary magmas 6 5 can be accurately calculated from the 18o of clinopyroxene mineral separates however the leucite mineral separates pure stoichiometric ka1si2o6 have 18o 8 8to 10 6 and clearly have not retained their primary igneous oxygen isotopic compositions the whole rock 18o values exhibit a positive correlation with h2o contents and extrapolation to a plausible water content for such a subaerially erupted lava 0 5 wt h2o gives a range of primary 18o values of 5 8 to 6 8 the much less hydrated bufumbira africa and gaussberg antarctica samples have 18o 6 7to 7 9and 6 1to 7 0 respectively these have probably undergone only minor subsolidus18o enrichments the san venanzo italy samples are even less hydrated so their extremely high 18o values of 10 8 to 12 0 are definitely magmatic values those data confirm our earlier conclusions that the leucite bearing magmas erupted in north central italy are unique in having much higher 18o values than potassic rocks from southern italy or anywhere else in the world the northward increase in 18o in the leucite bearing rocks of italy is thus clearly a manifestation of progressively greater interaction between mantle derived magmas 18o 5 5to 7 5 and the high 18o sedimentary and metasedimentary rocks of the italian continental crust 18o 15to 25 which were strongly heated during the episode of tuscan anatectic granitic magmatism

oxygen and strontium isotopic investigations of subduction zone volcanism the case of the volcano arc and the marianas island arc abstract recent fresh volcanic rocks of the intra oceanic mariana and volcano arcs were analyzed for o and sr isotopic compositions in order to determine the source of these magmas fresh non arc volcanic rocks from the regions surrounding the mariana volcano arcs and some dsdp sediments were also analyzed for comparison the oxygen isotopic ratios of the arc lavas 5 5 6 8 exhibited a small inter island variation that cannot be entirely explained by fractional crystallization the sr isotopic composition of the arc lavas is remarkably uniform 0 70332 0 70394 for the marianas three models are considered in order to explain the observed isotopic characteristics 1 bulk mixing and melting of morb type mantle with a subducted sediments and b subducted oceanic crust excluding sediments 2 melting of a mixture of sediment derived fluids and morb type mantle and 3 melting of a mixture of sediment derived fluids and oceanic island or hot spot type mantle the last model fits the data best the conclusion that very small and variable amounts of sediment derived fluid 1 are required to explain the observed inter island o isotopic variation is consistent with that of other workers who used different isotopic and trace element methods the generation of magmas in the mariana volcano arcs involves very little sediment and the source region of mariana lavas is isotopically indistinguishable from that of hot spot basalts

covariance of initial 87sr 86sr ratios δ18o and sio2 in continental flood basalt suites the role of contamination and alteration when mutual positive correlations occur between delta sup 18 o sup 87 sr sup 86 sr initial ratio r sub o and sio sub 2 in continental flood basalt suites they are generally accepted as being due to crustal contamination in continental flood basalt suites that have undergone coupled assimilation fractional crystallization in which the contaminant is granitic continental crust r sub o reflects the degree of contamination and will correlate positively with sio sub 2 which reflects the degree of differentiation posteruptive alteration of a suite having a range of sio sub 2 values should result in a positive correlation between sio sub 2 and delta sup 18 o because the ability of a volcanic rock to concentrate sup 18 o depends in part on silica content suites that have undergone assimilation fractional crystallization followed by alteration after eruption may there for exhibit a positive correlation between delta sup 18 o sio sub 2 and r sub o the delta sup 18 o data in such suites may consequently suggest erroneously high degrees of contamination

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

the b isotopic composition of arc lavas from martinique lesser antilles island arc samples from martinique lesser antilles are enriched in b relative to oceanic crust or the mantle with b contents varying between 5 and 54 ppm and have 11b falling in a range between 1 8 and 5 3 less than the 11b of altered oceanic crust the combination of these results indicates that both sediments and altered oceanic crust must have been involved in the generation of those magmas since the abundance of b in the mantle is too low to produce such low 11b values with such high b concentrations b content and 11b are not correlated showing that the amount of b added to the arc magma was decoupled from its isotopic composition by the mixing of at least three distinct components boron concentrations considered in conjunction with 87sr 86sr 143nd 144nd 18o and 11b data show that variable amounts of b were added by a b enriched fluid to different batches of mantle derived magma the b sr and nd isotopic compositions of these samples are consistent with a two stage process in which enriched magma is produced in the mantle wedge by the addition of an aqueous fluid derived from dehydrating subducting lithosphere and then modified during ascent by assimilation of variable amounts of sediment and altered oceanic crust most of the b contained in the fluid was probably derived from altered oceanic crust plus as little as 3 sediment while the material involved in assimilation was apparently largely continentally derived sediment a two stage process like this also explains the distribution of 18o within the context of the b sr and nd isotopic compositions of martinique arc lavas

temporal association of arc continent collision progressive magma contamination in arc volcanism and formation of gold rich massive sulphide deposits on wetar island banda arc whole rock 87sr 86sr and 18o analyses of volcanic rocks and 3he 4he analyses of sulphides and sulphates from mineralized rocks on wetar indonesia indicate a variable contribution of assimilated crustal material or sediment sourced from the subducted australian craton to the south these new data support the idea of progressive source contamination with precisely dated events showing that wetar island hosts the most extreme examples of crustal assimilation in the region the increased continental contamination occurs during the pliocene zanclian to piacenzian during distinct magmatic events between 5 and 4 ma and at 2 4 ma when 87sr 86sr ratios in unaltered lavas with whole rock 18o values between 5 7 and 9 6 increase from 0 707484 to extreme radiogenic values of 0 711656 the earlier of these magmatic events is important in the generation of the hydrothermal systems responsible for the mineralization recorded on wetar samples from this yield radiogenic 3he 4he ratios between 0 5 and 1 4 r ra similar to the data from volcanic rocks on nearby romang the later magmatic event coincides with the arrival of the australian continental margin at the subduction zone along the banda arc progressive incorporation of continental sourced components into the source region below the wetar island edifice coincides with the formation of gold rich volcanogenic massive sulphide deposits hosted within the contaminated volcanic pile

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

evolution of high ca high sr c series basalts from grenada lesser antilles the effects of intra crustal contamination basaltic lavas from grenada lesser antilles may be divided into two series on the basis of cao mgo relations the c series roughly corresponds to the ankaramites or high sr series of the earlier literature and may be distinguished from the m series basalts by higher cao at a given mgo and by their strongly augite phyric nature compositional variation within the c series is dominated by fractional crystallization of augite and plagioclase but this was accompanied by assimilation of sedimentary material from the island arc crust the assimilation fractional crystallization process is well illustrated by an increase in 206pb 204pb from 18 6 to 19 4 with fractionation and correlated increases in nd sr zr sm and rb ba the most primitive members of the c series can not be generated from erupted m series near primary basalts but instead show evidence for an origin by olivine fractionation from high mg basalts never seen at the surface these appear to have been derived from a source similar to that of morb but enriched in 87sr and other hydrophile elements by dehydration of subducted lithosphere and in ree and radiogenic pb by a small component of subducted sediment

stable isotope compositions and water contents of boninite series volcanic rocks from chichi jima bonin islands japan measurements of stable isotope compositions and water contents of boninite series volcanic rocks from the island of chichi jima bonin islands japan confirm that a large amount 1 6 2 4 wt of primary water was present in these unusual magmas an enrichment of 0 6 in18o during differentiation is explained by crystallization of18o depleted mafic phases silicic glasses have elevated 18o values and relatively low d values indicating that they were modified by low temperature alteration and hydration processes mafic glasses on the other hand have for the most part retained their primary isotopic signatures since eocene time primary d values of 53 for boninite glasses are higher than those of morb and suggest that the water was derived from subducted oceanic lithosphere

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

geochemistry of metamorphosed volcanic rocks in the neoarchean qingyuan greenstone belt north china craton implications for geodynamic evolution and vms mineralization abstract the qingyuan greenstone belt qgb situated in the northeastern section of the north china craton ncc is considered to be the unique metallogenic province in china that hosts both banded iron formations bifs and volcanogenic massive sulfide vms deposits traditionally the qgb is divided into the hunbei and hunnan terranes separated by the hunhe fault and grouped into the lower shipengzi middle hongtoushan and upper nantianmen formations which have undergone amphibolite to granulite facies metamorphism exposed supracrustal rocks are composed of plagioclase amphibolite and biotite plagioclase gneiss with minor amounts of bif marble and schist in this study detailed field and petrographic observations lithogeochemical u pb geochronological as well as whole rock sm nd isotope analyses were conducted on the metamorphosed mafic and felsic volcanic rocks i e plagioclase amphibolite and biotite plagioclase gneiss respectively in the qgb in order to discuss implications for tectonic evolution and comitant vms mineralization the supracrustal rocks of both hunbei and hunnan regions were formed synchronously from 2 57 to 2 53 ga and then had undergone 2 52 2 48 ga regional metamorphism specifically the lower section of the shipengzi formation is composed dominantly of transitional tholeiitic basalts with negative nb anomalies suggesting that they were likely generated by partial melting of a mantle source that was previously altered by variable amounts of slab derived fluids or melts in contrast the lithologic assemblages grade upward into interlayered bimodal volcanic rocks i e n morb type tholeiitic basalts and fi to fii type dacites of transitional to calc alkalic affinities representing a change in tectonic regime related to subduction from compression to extension among them all the basalts are characterized by consistently positive initial nd compositions end t 2 7 to 3 4 further indicate a depleted mantle source whereas those dacites possess negative to positive initial nd values end t 4 6 to 3 0 suggesting they were formed by partial melting of depleted mafic source likely lower mafic crust and accompanied with variable addition of old crustal material significantly vms deposits are genetically linked to this extensional event and closely associated with the fii type dacites that were generated by higher melting degree at high temperature conditions and shallow crustal level likely 10 15 km in all geochemical features e g negative nb anomalies and end value together with contamination from continental crusts for tholeiitic mafic rocks and inherited zircons from these volcanic rocks imply a continental arc setting where the qgb was evolved

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

mechanisms of contamination in lesser antilles island arc magmas from radiogenic and oxygen isotope relationships abstract oxygen sr and nd isotopic compositions for 29 volcanic samples from the lesser antilles are reported these span a considerable range in 18o from values similar to those of mantle derived lavas 18o 6 6 to 18o 14 0 although the highest 18o results are obtained from evolved andesites and dacites there is no clear correlation between 18o and sio2 an attempt is made to eliminate the effects of varying magma chemistry on 18o through differentiation by normalising to the chemical index of garlick 1 this enables the effects on 18o of processes other than magmatic fractionation to be more clearly assessed it is concluded that the range in 18o values measured cannot result from hydrothermal interaction or weathering alone although limited alteration of a few samples may be responsible for some scatter in the oxygen isotope data when 18o is plotted against radiogenic isotopic compositions well correlated trends are observed 18o increases with increasing87sr 86sr and decreasing143nd 144nd such behaviour is consistent with the contamination of mantle derived magmas by variable amounts of an ancient crustal component the shapes of mixing curves defining this process suggest that contamination occurs largely within the arc crust constraints from geochemical and geophysical data suggest that a terrigenous sediment intercalated within the arc crust is assimilated however subsequent fractional crystallisation at more shallow levels in the crust has obscured any chemical trends which might have resulted from combined assimilation fractional crystallisation furthermore it is suggested that the mantle derived magma has already undergone source contamination by the introduction of a slab derived fluid into the overlying mantle wedge

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

geochemical evolution of st kitts and montserrat lesser antilles the volcanic rocks of st kitts have uniform 87 sr 86 sr ratios c 0 7037 and high 143 nd 144 nd ratios c 0 5130 in a suite which ranges from basalt to rhyolite trace element abundances and the flat chondrite normalized ree patterns resemble those of island arc tholeiitic suites in comparison the montserrat lavas have higher concentrations of alkaline elements and are lree enriched geochemical differences may be related to partial displacement of the axis of the volcanic arc about 9 ma this would have led to the development of the st kitts suite in an essentially new and immature island arc environment being closer to the junction with the former arc axis the composition of the montserrat lavas may reflect previous subduction related mantle enrichment and or the influence of a sedimentary component isotopic ratios and most trace elements in the redonda basalt indicate island arc tholeiite or in some respects morb affinities but it has a high sr content and is lree enriched despite its distinctive composition redonda is situated on the main axis of the volcanic arc and its lavas were evidently contemporaneous with the younger eruptions of st kitts and montserrat

nd sr o isotopic and chemical evidence for a two stage contamination history of mantle magma in the central alpine bergell intrusion two different contamination processes have been identified as having been operative in the genesis of a plutonic suite initial contamination of a mantle source and subsequent crustal contamination of uprising partial melts from the mantle these processes are indicated by a detailed analyses of nd sr and oxygen isotopes together with major and trace elements of the 32 30 ma calc alkaline bergell intrusion this intrusion is located at the suture of the alpine continental collision zone and contains rock types capable of discriminating between mantle and intracrustal processes a range from basaltic andesitic dykes in the surrounding country rocks cumulitic hornblendites gabbros tonalite granodiorite and lamprophyres to pegmatites and aplites is exposed in this single intrusion the results of ree modelling and isotopic compositions of the basic members suggest that the cumulates were fractionated from a picrobasaltic liquid originating by partial melting of enriched subcontinental mantle end 4 increases in 87sr 86sr 0 7055 and 18o 6 7 in these samples relative to the mantle array and compositions of other periadriatic intrusions are most likely the result of an initial contamination of the mantle source by dehydration or partial melting of altered subducted oceanic crust slight differentiation of such a picrobasaltic liquid produced the basaltic andesitic dykes simultaneous fractional crystallization and contamination of the uprising magma by continental crust produced crustal isotopic signatures which increase with acidity to values of end 7 6 87sr 86sr 0 716 and 18o 10 the crustal imprint and lree enrichment in the dominating tonalite increase with decreasing crystallization depth which indicates that the tonalites were emplaced in several distinct batches with different degrees of contamination shoshonitic lamprophyres which intruded into the partly solidified granodiorite were generated in a deep strongly contaminated mantle source the posttectonic 26 ma novate leucogranite is not cogenetic with the main bergell body but rather formed from a predominantly crustal source if the described features are indeed due to mantle source contamination processes which are well known for volcanic arcs it must be concluded that these may also play a significant role in the genesis of calcalkaline plutonic suites

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

correlations between oxygen isotopic composition and petrologic setting in a coarse grained ca al rich inclusion abstract oxygen isotopic compositions in conjunction with petrologic investigation have been determined for a coarse grained type b2 ca al rich inclusion cai from the reduced cv3 vigarano using secondary ion mass spectrometry the oxygen isotopic compositions of minerals are distributed along the carbonaceous chondrite anhydrous mineral line indicating mixing between 16o rich and 16o poor nebular components the o isotopic heterogeneities among and within minerals in the cai interior indicate that cai formation started in an 16o rich nebula and subsequently continued in an 16o poor nebula 16o rich signatures of melilite and fassaite in the wark lovering rim and of olivine of the accretionary rim indicate that the nebular environment during formation of the cai returned to an 16o rich composition after processing in an 16o poor nebula these o isotopic variations in the cai support multiple heating events in the solar nebula and indicate that the nebular environments fluctuated from 16o rich to 16o poor and back to 16o rich compositions during the formation of a single cai

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

hydrogen isotope systematics of submarine basalts the d h ratios and water contents in fresh submarine basalts from the mid atlantic ridge the east pacific rise and hawaii indicate that the primary d h ratios of many submarine lavas have been altered by processes including 1 outgassing 2 addition of seawater at magmatic temperature and 3 low temperature hydration of glass decreases in d and h2o from exteriors to interiors of pillows are explained by outgassing of water whereas inverse relations between d and h2o in basalts from the galapagos rise and the famous area are attributed to outgassing of ch4 and h2 a good correlation between d values and h2o is observed in a suite of submarine tholeiites dredged from the kilauea east rift zone where seawater added directly to the magma affected only the isotopic compositions of hydrogen and argon analyses of some glassy rims indicate that the outer millimeter of the glass can undergo lowtemperature hydration by hydroxyl groups having d values as low as 100 d values vary with h2o contents of subaerial transitional basalts from molokai hawaii and subaerial alkali basalts from the society islands indicating that the primary d values were similar to those of submarine lavas extrapolations to possible unaltered d values and h2o contents indicate that the primary d values of most thoteiite and alkali basalts are near 80 5 the weight percentages of water are variable 0 15 0 35 for mor tholeiites about 0 25 for hawaiian tholeiites and up to 1 1 for alkali basalts the primary d values of 80 for most basalts are comparable to those measured for deep seated phlogopites these results indicate that hydrogen in marked contrast to other elements such as sr nd pb and o has a uniform isotopic composition in the mantle this uniformity is best explained by the presence of a homogeneous reservoir of hydrogen that has existed in the mantle since the very early history of the earth

segmentation of the lesser antilles subduction zone abstract precise hypocentral locations of earthquakes recorded on local seismic networks from 1978 to 1984 have established the configuration of the benioff zone beneath the lesser antilles island arc there are two distinct segments to the zone one to the north of martinique which trends nnw and one to the south of st lucia which trends nne the northern zone dips at 60 50 the southern zone has a dip of 50 45 in the north but is vertical in the south pleistocene volcanoes are aligned in distinct segments which closely mirror the kink in the benioff zone mid miocene swarms of dykes in martinique and st lucia have nw and ne azimuthal modes respectively we interpret this to mean that this kink in the subduction zone existed as long ago as the miocene the kink may represent the deformation of a single subducting plate or two separate north and south american plates subducting beneath the caribbean plate with a triple junction in the region of martinique st lucia

sr and o isotope constraints on source and crustal contamination in the high k calc alkaline and shoshonitic neogene volcanic rocks of se spain the neogene volcanic province of se spain nvps is characterized by calc alkaline ca high k calc alkaline kca shoshonitic sh ultrapotassic up and alkaline basaltic ab volcanic series all these series except the ab have high lilerlree lilerhfse and brbe ratios and high but variable sr pb and o isotope compositions the kca and sh lavas contain metapelitic xenoliths whose mineralogical and chemical composition are typical of anatectic restites the geochemical characteristics of ca kca sh and up series suggest that they originated from the lithospheric mantle previously contaminated by fluids derived from pelagic sediments additionally the presence of restite xenoliths in the kca and sh lavas indicates some sort of interaction between the mantle derived magmas and the continental crust trace element and isotope modeling for the kca and sh lavas and the restites point towards the existence of two mixing stages during the first stage the lithospheric mantle was contaminated by 1 5 of fluids derived from pelagic sediments which produced

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

geochemistry of basalts from central and southern new hebrides arc implication for their source rock composition abstract the basaltic rocks from the central and southern islands of the new hebrides aneityum tanna erromango efate emae tongoa and epi have geochemical features typical of island arc volcanics they are enriched in lile and depleted in zr hf nb and ta compared to n type morb the rocks were derived from a similar upper mantle source as n type morb but with a higher degree of partial melting in addition their source was enriched in lile k rb sr ba and lree probably by migrating hydrous fluids released during the dehydration of the subducted oceanic slab the basalts from futuna island which is located farther from the trench display characteristics typical of calc alkaline rocks the futuna basalts were generated from a different lile enriched upper mantle source it seems that this upper mantle source was modified by interaction with partial melts from the subducted oceanic lithosphere

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

assimilation of sediments embedded in the oceanic arc crust myth or reality abstract arc magmas are commonly assumed to form by melting of sub arc mantle that has been variably enriched by a component from the subducted slab although most magmas that reach the surface are not primitive the impact of assimilation of the arc crust is often ignored with the consequence that trace element and isotopic compositions are commonly attributed only to varying contributions from different components present in the mantle this jeopardises the integrity of mass balance recycling calculations here we use sr and o isotope data in minerals from a suite of volcanic rocks from st lucia lesser antilles arc to show that assimilation of oceanic arc basement can be significant analysis of 87sr 86sr in single plagioclase phenocrysts from four soufriere volcanic complex svc st lucia hand samples with similar composition 87sr 86sr 0 7089 0 7091 reveals crystal isotopic heterogeneity among hand samples ranging from 0 7083 to 0 7094 with up to 0 0008 difference within a single hand sample o 18 measurements in the svc crystals show extreme variation beyond the mantle range with 7 5 to 11 1 for plagioclase n 19 10 6 to 11 8 for quartz n 10 9 4 to 9 8 for amphibole n 2 and 9 to 9 5 for pyroxene n 3 while older lavas pre soufriere volcanic complex with less radiogenic whole rock sr composition 87sr 86sr 0 7041 0 7062 display values closer to mantle range 6 4 to 7 9 for plagioclase n 4 and 6 to 6 8 for pyroxene n 5 we argue that the 87sr 86sr isotope disequilibrium and extreme o 18 values provide compelling evidence for assimilation of material located within the arc crust positive correlations between mineral o 18 and whole rock 87sr 86sr 143nd 144nd and 206 207 208pb 204pb shows that assimilation seems to be responsible not only for the isotopic heterogeneity observed in st lucia but also in the whole lesser antilles since st lucia encompasses almost the whole arc range of isotopic compositions this highlights the need for detailed mineral scale investigation of oceanic arc suites to quantify assimilation that could otherwise lead to misinterpretation of source composition and subduction processes

lead isotopic compositions of south sandwich island volcanic rocks and their bearing on magmagenesis in intra oceanic island arcs pb isotope ratios have been measured in 12 volcanic rocks from the south sandwich islands the ranges are 206pb204pb 18 51 18 66 207pb204pb 15 55 15 64 208pb204pb 38 42 38 64 in 207pb204pb 206pb204pb and 208pb204pb 206pb204pb correlation diagrams the south sandwich data plot distinctly above the fields for ocean ridge basalts and yield trends showing apparent mixing with a sedimentary end member similar to south atlantic pelagic sediments as reported by chow and patterson 1962 and this study armstrong and cooper 1971 have likewise shown that volcanics from the lesser antilles show mixing trends with north atlantic sediments in pb isotope correlation diagrams the north atlantic sediments have distinctly higher 206pb204pb and 208pb204pb ratios compared to the south atlantic sediments the parallel relationships between sediments and volcanic island arc rocks of the north and south atlantic provide strong evidence for a component of pb from subducted sediments in the lavas of the west atlantic basin in contrast to these data lavas from the mariana arc in the western pacific show little or no component of pb from pelagic sediments the reason for the different behaviors in the two settings is speculative

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

miocene subduction related magmatism in southern sardinia sr nd and oxygen isotopic evidence for mantle source enrichment abstract subduction beneath southern sardinia in miocene times gave rise to a suite of basalts basaltic andesites high k andesites and rhyolitic ignimbrites the monte arcuentu volcanic complex is a typical product of this activity although the volcanic rocks display some tholeiitic affinities in terms of k 2 o sio 2 relations they resemble calc alkaline lavas of the aeolian and aegean arcs the most mafic members of the suite have moderately high ni 164 ppm and cr 550 ppm contents and high mgo 10 wt and are therefore mantle derived mantle normalised trace element patterns show high k rb ba and th but low nb and ta characteristic of subduction related magmas sr contents in almost all samples are particularly low 165 265 ppm 87 sr 86 sr i values range from 0 7054 to 0 7113 whilst nd i is between 0 9 and 8 8 the sr nd isotopic field overlaps those of the high k rocks of roccamonfina and the roman volcanic province and extends that of the aeolian islands and the aegean arc correlations of radiogenic isotope ratios with sio 2 values in bulk rocks are much stronger than with mgo conventionally analysed 18 o whole rock values range from 6 4 in basalt to 12 4 in a high k andesite however 18 o values for clinopyroxene phenocrysts analysed by a laser fluorination method range from 6 17 to 7 46 good correlations are seen between 18 o cpx values and both mgo and sio 2 differences between 18 o whole rock and 18 o cpx values are probably due to late stage alteration of the groundmass and cast doubt on the validity of petrogenetic interpretations based solely on whole rock oxygen isotope analysis the sr nd o isotopic variation can be modelled either by contamination of mantle derived magmas by hercynian continental crust or by extensive enrichment of the mantle source by subducted sediments in the 18 o cpx vs 87 sr 86 sr i diagram crustal contamination hyperbolae are concave upward because of the low sr contents of the monte arcuentu magmas so both crustal contamination trends and mantle enrichment trends can generate the same isotopic relationships however the strong correlations of radiogenic isotopic ratios with sio 2 and the weak correlations with mgo are most easily explained by extensive 2 10 mantle enrichment by subducted siliceous sediments the correlation between sio 2 and 87 sr 86 sr i for the monte arcuentu magmas is very unusual within subduction related magmatism whereas that between 18 o and 87 sr 86 sr appears to show that the suite forms an end member composition for many island arc and active continental margin volcanic suites

new geochemical constraints for the origin of ridge subduction related plutonic and volcanic suites from the chile triple junction taitao peninsula and site 862 leg odp141 on the taitao ridge abstract several features of neogene and quaternary magmatism in the region south of the present day chile triple junction ctj at 46 12 s are directly related to the migration of the triple junction due to the obliquity of the ridge orientation with respect to the subduction front the triple junction migrated from south to north during the last 14 ma the taitao peninsula the westernmost promontory of the chile coast and the taitao ridge a submarine promontory north of the taitao peninsula provide the most complete collection of ridge subduction related magmatic products in the region the emplacement of near trench volcanics the intrusion of a variety of plutonic rocks and the related hydrothermal activity at these two sites have been interpreted as resulting from magma interactions between subducted ridge segments of the chile spreading centre and the continental crust we present new field observations and geochemical data that help to better constrain the problem of the sources and evolution of the taitao magmas the new geochemical data were obtained on samples collected from the taitao peninsula during a field expedition in 1995 and from samples of the taitao ridge during leg odp141 site 862 which have been re sampled in 1996 by one of us selected major and trace element compositions of 20 volcanic rocks from the taitao ridge are discussed together with 53 analyses from different rock types from the taitao peninsula including 24 unpublished analyses nd and sr isotopic compositions were obtained from 5 whole rocks and separated minerals of the taitao peninsula together with the oxygen isotope composition of four separated clinopyroxenes six main magmatic types are identified 1 n type morb 2 e type morb 3 lree depleted morb showing some trace element features typical of arc basalts 4 moderately nb depleted e morb 5 calc alkaline andesites dacites and rhyolites and 6 andesites and dacites with adakitic signature chemical similarities exist between some forearc magmas of the taitao ridge and the taitao peninsula and magmas emplaced at the chile active spreading ridge one important result based on isotope data is that the lavas emplaced over the continental crust taitao peninsula did not originate from melting of continental crust nor from extensive assimilation of such a crust by mantle derived magmas the likely source of these basalts could be the hot convective oceanic mantle of the southern chile spreading ridge buried at moderate depth 10 30 km

mineralogical and geochemical evolution of the 1982 1983 galunggung eruption indonesia pyroclastic deposits from the 1982 1983 eruption of galunggung volcano java indonesia reflect preeruptive magmatic evolution which is of interest because of 1 its duration of nine months compared to a few hours or days for most historical eruptions 2 the diversity of eruptive styles from ash and scoria flows to phreatomagmatic explosions and to the strombolian activity that marked the end of the eruption and 3 the progressive variation in chemical composition with time from andesite 58 wt sio2 to high mg basalt 47 wt sio2 the 1982 1983 galunggung basalts are rather primitive 10 to 12 wt mgo 180 to 200 ppm ni and 550 to 700 ppm cr despite the presence of about 40 phenocrysts they may represent the most primitive basalts recognized in western java basalts contain phenocrysts of olivine fo90 80 diopside salite and plagioclase an95 75 andesites contain plagioclase an80 60 augite hypersthene en67 64 and titanomagnetite the distribution of mineral compositions in each petrographic type is nearly unimodal although scarce plagioclase and olivine xenocrysts have been observed abundance of gabbroic cumulates associated with the pyroclastic flows and evolution of mineral compositions from high mg basalts to andesites support crystal fractionation as the main differentiation mechanism although magma mixing of basaltic andesite and andesite cannot be excluded major and trace element trends which display rough decreases of mgo cao ni cr with increasing degree of differentiation and also linear positive correlations of hygromagmaphile elements are compatible with both processes however some discrepancies are observed between major and trace element modelling which may be explained to some extent by the influence of in situ crystallization and or magma mixing the constancy of 143nd 144nd 0 51286 3 230th 232th 0 65 0 02 th u 4 08 0 07 ratios and to a lesser extent 18o values 5 8 to 6 4 smow and 87sr 86sr ratios 0 70440 to 0 70468 is compatible with a magmatic evolution through fractional crystallization without significant crustal contamination nevertheless low 18o and high 87sr 86sr values in basaltic andesites may be due to the introduction of meteoric fluids into the galunggung magma

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

strontium isotopic and selected trace element variations between two aleutian volcanic centers adak and atka implications for the development of arc volcanic plumbing systems major and trace element concentrations and initial 87sr 86sr ratios of lavas from the aleutian volcanic centers of adak and atka have been used to study the evolution of their respective lithospheric plumbing systems the centers are within 150 km of one another and show similar overall silica ranges 47 67 but adak 40 km3 is smaller than atka 200 km3 adak s lavas are chemically and isotopically heterogeneous 87sr 86sr 0 70285 0 70330 and two units contain lithospheric xenoliths the lavas of the much larger atka on the other hand have much less variability in major and trace elements as well as 87sr 86sr 0 70320 0 70345 we suggest that these characteristics are a measure of the relative maturity and cleanliness of the lithospheric plumbing systems that supply magma to these centers because aleutian volcanic centers often remain fixed for relatively long periods of time 5 m y once established magmatic passageways are repeatedly used young plumbing systems are relatively cool and contain large amounts of wallrock contaminant and ascending magmas undergo contamination as well as concurrent crystallization and fractionation with time however heat and mass transfer between ascending magmas and wallrock produce thermal and chemical boundary layers that insulate subsequent magmas in effect the plumbing system matures the chemical heterogeneity displayed by young dirty systems like adak reflects not only the magma source but also the wallrock encountered during ascent and possibly the effects of extensive crystal fractionation thus it is the petrologic data of mature clean systems like atka that yield the most direct and unambiguous information on the ultimate origin of the lavas and their near surface evolution

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

oxygen isotope geochemistry of the lassen volcanic center california resolving crustal and mantle contributions to continental arc magmatism this study reports oxygen isotope ratios determined by laser fluorination of mineral separates mainly plagioclase from basaltic andesitic to rhyolitic composition volcanic rocks erupted from the lassen volcanic center lvc northern california plagioclase separates from nearly all rocks have o values 6 1 8 4o higher than expected for production of the magmas by partial melting of little evolved basaltic lavas erupted in the arc front and back arc regions of the southernmost cascades during the late cenozoic most lvc magmas must therefore contain high o crustal material in this regard the o values of the volcanic rocks show strong spatial patterns particularly for young rhyodacitic rocks that best represent unmodified partial melts of the continental crust rhyodacitic magmas erupted from vents located within 3 5 km of the inferred center of the lvc have consistently lower o values average 6 3o 0 1o at given sio2 contents relative to rocks erupted from distal vents 47 0 km average 7 1o 0 1o further magmas erupted from vents situated at transitional distances have intermediate values and span a larger range average 6 8o 0 2o basaltic andesitic to andesitic composition rocks show similar spatial variations although as a group the o values of these rocks are more variable and extend to higher values than the rhyodacitic rocks these features are interpreted to reflect assimilation of heterogeneous lower continental crust by mafic magmas followed by mixing or mingling with silicic magmas formed by partial melting of initially high o continental crust 9 0o increasingly hybridized by lower o 6 0o mantle derived basaltic magmas toward the center of the system mixing calculations using estimated endmember source o values imply that lvc magmas contain on a molar oxygen basis approximately 42 to 4 isotopically heavy continental crust with proportions declining in a broadly regular fashion toward the center of the lvc conversely the o values of the rhyodacitic rocks suggest that the continental crust in the melt generation zones beneath the lvc has been substantially modified by intrusion of mantlederived basaltic magmas with the degree of hybridization ranging on a molar oxygen basis from approximately 60 at distances up to 12 km from the center of the system to 97 directly beneath the focus region these results demonstrate on a relatively small scale the strong influence that intrusion of mantle derived mafic magmas can have on modifying the composition of pre existing continental crust in regions of melt production given this result similar but larger scale regional trends in magma compositions may reflect an analogous but more extensive process wherein the continental crust becomes progressively hybridized beneath frontal arc localities as a result of protracted intrusion of subduction related basaltic magmas

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

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