ka band backscattering from water surface at small incidence a wind wave tank study we report on an experiment conducted at the large pytheas wind wave facility in marseille to characterize the ka band radar return from water surfaces when observed at small incidence simultaneous measurements of capillary gravity to gravity wave height and slopes and normalized radar cross section nrcs were carried out for various wind speeds and scattering angles from this data set we construct an empirical two dimensional wave number spectrum accounting for the surface current to describe water surface motions from decimeter to millimeter scales some consistency tests are proposed to validate the surface wave spectrum which is then incorporated into simple analytical scattering models the resulting directional nrcs is found in overall good agreement with the experimental values comparisons are performed with oceanic models as well as in situ measurements over different types of natural surfaces the applicability of the present findings to oceanic as well as continental surfaces is discussed

chloritisation along the thanewasna shear zone western bastar craton central india its genetic linkage to cu au mineralisation abstract the cu au mineralisation of thanewasna bastar craton central india is hosted in quartz chlorite veins traversing granitoid rocks mineralisation and associated alteration are controlled by a nw se trending brittle ductile shear zone large scale alkali magmatism in the form of k rich granite emplacement is found in the vicinity of the shear zone the emplacement of this granite 1587 14 ma along the northern shoulder of the godavari rift produced a high geothermal gradient resulting in intense chloritisation and mineralisation field and petrographic studies show that the chlorite formed in two possible modes viz a replacement of ferromagnesian minerals of the host rock and or b precipitated directly from hydrothermal solutions mineral chemistry epma coupled with sem and xrd studies reveals that chamosite with minor clinochlore varieties of chlorite is commonly associated with cu and au mineralisation chlorite shows variation in fe fe mg ratios from 0 54 to 0 60 0 55 to 0 64 and 0 49 to 0 55 and al iv from 1 88 to 2 40 1 91 to 2 50 and 1 80 to 1 94 apfu respectively at the surface and in the sub surface mineralisation and host rock empirical and thermodynamic geothermometers have been used to determine the temperature of chlorite formation based on chemical composition six empirical methods based on al iv al vi and fe fe mg ratio showed a temperature range of 187 c to 381 c temperatures of chlorite formation have also been determined by the thermodynamic solid solution method the thermodynamic equations of three intra crystalline equilibria at 2 kbar pressure show that temperature ranges from 215 to 454 c for low si contents 2 8 apfu the thermodynamic method of vidal et al 2001 and 2005 was not so compatible for an estimation of temperature of hydrothermal fe rich chlorites associated with cu au mineralisation at the thanewasna copper deposit tcd the temperature of chlorite formation increases from the host rock mean 201 c to proximal mineralisation zone mean 234 c to distal k na alteration zone mean 251 c integrating field and laboratory results suggested that tcd chlorite is part of a structurally controlled high sulphidation epithermal system this characterization would help in the regional exploration for base and precious metals and the results are applicable for the entire western bastar craton wbc of central india and similar deposit elsewhere

wave turbulence interactions in the upper ocean part ii statistical characteristics of wave and turbulent components of the random velocity field in the marine surface layer abstract we present the results of an analysis of field data collected by donelan who used a miniature drag sphere to measure velocities beneath wind waves on lake ontario linear statistical techniques are used to separate the velocity into wave and turbulent parts while we mostly aim at demonstrating the effects of surface wind waves on the statistical characteristics of the turbulent field in the upper mixed layer we also interpret several features of the data on the hags of recent theoretical results one of the most intriguing features of the turbulent velocity spectra so obtained is a large peak near the dominant wave frequency we review various possible explanation for this behavior although we prefer a model in which the turbulence is assumed frozen on the timescale of the waves this model requires no new dynamics and gives explicit formulae relating the dissipation rate to the magnitude of the spectral densities for high and low frequencies on this basis we have determined a dissipation leng

field measurements of duration limited growth of wind generated ocean surface waves at young stage of development abstract the issue of duration limited growth of wind generated waves is of importance to wave studies most analytical solutions for wind waves are given in time rather than fetch domain numerical modeling of wave development is also often conducted in temporal evolution mode experimental data of duration limited growth however are rare and do not cover a wide range of the wave development stage as a result theorists and modelers have to rely on fetch limited evolution data converting them into duration limited conditions on the basis of some assumptions during one of the field experiments of wind wave measurements a dataset was obtained that is almost ideal for duration limited wave growth analysis the dataset extends the range of coverage in dimensionless time of the existing database by about one order of magnitude the results of analysis provide strong support for the relation of space time conversion for rendering the fetch limited growth functions to duration limited growth functions qu

the sudbury structure as a terrestrial mare basin this paper reviews the origin development and present status of the hypothesis that the sudbury structure of ontario canada is a deformed precambrian impact crater analogous to the circular lunar maria the petrologic similarity of the maria and terrestrial lopoliths such as the bushveld duluth and sudbury igneous complexes was suggested in 1961 assuming these to be extrusive features roofed by their own silicic differentiates this led to the proposal by r s dietz in 1962 that the sudbury structure was a tectonically deformed impact basin occupied by an extrusive lopolith and analogous to the small lunar maria he then searched for and found shatter cones at sudbury discovery of shock metamorphic features in the onaping formation by b m french in 1967 showed that this formation was a fallback breccia detailed studies since the 1970s have further strengthened the impact theory isotopic and impact modeling investigations have shown that the sudbury igneous complex may be largely impact melt rather than internally generated magma the shape and size of the original impact crater are not well known the absence of compressional deformation of the north range supports an originally elliptical shape which has been shown to be similar to those of impact craters on the moon and mars however field mapping and reflection profiling suggest that much of the present ellipticity may have been produced by northwest directed ductile thrusting concentrated on the south range and interior of the complex the size of the original structure is also uncertain recent investigations indicate that the present igneous complex is only the central part of a much larger and perhaps multiring structure the analogy between the sudbury structure and lunar maria though petrologically wrong is valid to the extent that both classes of structure were initially formed by impact however the size and shape of the original crater and the degree to which the sudbury intrusive complex and its ore deposits are impact generated are still open to debate

gnss r nonlocal sea state dependencies model and empirical verification global navigation satellite system reflectometry gnss r is an active bistatic remote sensing technique operating at l band frequencies gnss r signals scattered from a rough ocean surface are known to interact with longer surface waves than traditional scatterometery and altimetry signals a revised forward model for gnss r measurements is presented which assumes an ocean surface wave spectrum that is forced by other sources than just the local near surface winds the model is motivated by recent spaceborne gnss r observations that indicate a strong scattering dependence on significant wave height even after controlling for local wind speed this behavior is not well represented by the most commonly used gnss r scattering model which features a one to one relationship between wind speed and the mean square slope of the ocean surface the revised forward model incorporates a third generation wave model that is skillful at representing long waves an anchored spectral tail model and a gnss r electromagnetic scattering model in comparisons with the spaceborne measurements the new model is much better able to reproduce the empirical behavior

high salinity fluid inclusions formed from recycled seawater in deeply subducted alpine serpentinite abstract the origin of high pressure brines has been investigated in the erro tobbio peridotite western alps a mantle slice that was exposed to the seafloor of the mesozoic ligurian piedmontese tethys and was later involved in alpine subduction hydrothermal alteration by seawater derived fluids led to replacement of the mantle assemblage by cl bearing serpentine 0 35 wt cl brucite 0 2 wt cl and alkali bearing phyllosilicates 0 2 wt cl 0 2 0 55 wt na2o 1 5 wt k2o relics of these hydrous phases occur in olivine titanian clinohumite antigorite assemblages formed at 2 5 gpa and 550 600 c during partial devolatilization and veining of the hydrothermally altered peridotite the high pressure phases lack chlorine and alkalis and are coeval with fluid inclusions trapped in the syn eclogitic veins the inclusions are salt saturated and contain up to 50 wt cl na k mg and fe high fluid chlorinity was probably achieved during rehydration of relict mantle minerals and deposition of hydrous phases in the veins the data presented suggest that the seafloor hydrothermal signature was inherited by the eclogitic fluid due to partitioning of chlorine and alkalis into the fluid phase the presence of salty brines in eclogitized hydrous peridotites can indicate deep recycling of seawater derived fluids hydrous ultramafic systems can therefore act as large scale carriers of seawater into the mantle

evolution of ocean slicks under a rising wind 1 airborne synthetic aperture radar and high resolution infrared imagery are used to examine the evolution of natural ocean slicks during a period of freshening wind initially the slicks are of the order of 50 m in width and have radar and thermal contrasts of the order of 10 db and several 0 1 c while there can be over time a transient reorganization of surface film material by internal waves the slicks are observed to disperse and are no longer detectible after 5 h the dispersion occurs through the action of langmuir circulation which results in along wind streaks or windrows as well as other effects prominent streaks occur preferentially along a slick s upwind side the downwind side resembling more of a leading edge at least early on over time the leading edge develops a corrugated shape and gaps begin to develop within the slicks the formation of gaps is compared with a conceptual model by dysthe 2006 for the tearing of a surface film in the region of positive surface straining eventually the slicks break into elongated patches that co exist with windrows which is consistent with the effects of advective dispersion

dynamics of surface currents over qingdao coastal waters in august 2008 1 surface currents measured by high frequency hf radar are used to investigate the dynamics in the coastal waters of qingdao china on the western coast of the yellow sea different factors affecting the surface currents are revealed by dynamical analysis harmonic tidal analysis shows that the coastal tidal currents are barotropic and their temporal evolution is mainly influenced by the semidiurnal tidal constitutes topography and geometry it is also found that their horizontal distribution represents the effect of local topography at sub tidal frequencies the high correlation between winds and the sub tidal surface currents indicates a crucial role of wind forcing in driving the currents varying wind direction coupled with small scale features of the coastal geometry results in complicated sub mesoscale circulation in addition the monthly coastal circulation is characterized by an eddy structure and is primarily determined by the outflow which is closely associated with the sea level slope along the coast the variability of the residual currents is studied by analyzing the cross shore momentum equation with wind stress sea level records and hf radar currents it is shown that both the barotropic pressure gradient and the nonlinear tidal stress contribute to the variations of the residual currents near the bay mouth and further govern the coastal monthly circulation in august 2008

azimuthal and radial variation of wind generated surface waves inside tropical cyclones abstractfor wind generated waves the wind wave triplets reference wind speed significant wave height and spectral peak wave period are intimately connected through the fetch or duration limited wave growth functions the full set of the triplets can be obtained knowing only one of the three together with the input of fetch duration information using the pair of fetch limited duration limited wave growth functions the air sea energy and momentum exchanges are functions of the wind wave triplets and they can be quantified with the wind wave growth functions previous studies have shown that the wave development inside hurricanes follows essentially the same growth functions established for steady wind forcing conditions this paper presents the analysis of wind wave triplets collected inside hurricane bonnie 1998 at category 2 stage along 10 transects radiating from the hurricane center a fetch model is formulated for any location inside the hurricane applying the fetch model to the 2d hurric

stable isotope composition of magmatic and deuteric carbonate phases in hypabyssal kimberlite lac de gras field northwest territories canada abstract the oxygen and carbon isotope compositions of carbonates from thirteen late cretaceous to paleogene hypabyssal intrusions from the lac de gras kimberlite field indicate that the carbonates are well preserved and have a complex paragenetic formation history kimberlites at ten localities studied are calcite bearing based on the presence of phenocrysts microphenocrysts and or millimeter scale calcite only segregations of sr rich calcite the calcite bearing kimberlites also contain large cm scale sr poor calcite serpentine segregations that are texturally distinct from the smaller sr rich calcite only segregations kimberlites at three other localities studied are dolomite bearing based on the presence of calcite dolomite segregations some of which preserve complex oscillatory and banded textures of calcite dolomite and magnesian calcite 18 o values for whole rock calcite in calcite bearing kimberlite and for micro samples of calcite from individual segregations in calcite and dolomite bearing kimberlite generally vary from 6 to 9 consistent with their formation at magmatic temperatures e g 750 c from a kimberlite melt in contrast higher 18 o values of 9 to 14 characterize micro samples of calcite from calcite serpentine segregations in calcite bearing kimberlite as well as whole rock dolomite and micro samples of dolomite from segregations in dolomite bearing kimberlite these data are consistent with formation from deuteric fluids late stage magmatic at sub solidus temperatures e g 500 to 100 c these higher 18 o values for whole rock calcite also correlate with increased intensity of forsterite alteration increased abundance of calcite serpentine segregations textural overprint of primary groundmass minerals by anhedral calcite and serpentine and development of atoll spinels all interpreted as a result of deuteric fluids in contrast whole rock calcite in dolomite bearing kimberlite has notably lower 18 o values of 1 5 to 5 5 interpreted to have formed from or been overprinted by locally derived high co 2 h 2 o deuteric fluids at 500 to 100 c 13 c values of the various types of calcite and dolomite 8 to 3 have no systematic variation with 18 o values and therefore there is no isotopic record of volatile degassing from these hypabyssal bodies

parental carbonatitic melt of the koala kimberlite canada constraints from melt inclusions in olivine and cr spinel and groundmass carbonate abstract this study of the hypabyssal kimberlite with particularly fresh olivine from the palaeogene koala pipe ekati cluster slave craton canada is focused on reconstruction of the kimberlite parental melt the koala kimberlite sample is a typical ultramafic rock archetypal or group i kimberlite containing large abundance of forsteritic olivine set in a carbonate rich matrix the euhedral olivine ii shows significant zoning in terms of forsterite content and trace elements only the rims of olivine ii are considered to be magmatic they are uniform in terms of fo 91 5 0 2 mol and host primary crystal apatite cr spinel and melt inclusions the magmatic spinel phenocrysts are strongly zoned from titanian magnesian chromite to pleonaste with the cores having the same composition as spinel inclusions in olivine the primary and pseudo secondary melt inclusions in both magmatic cr spinel and olivine comprise a complex assemblage of daughter phases dominated by carbonate minerals dolomite eitelite na 2 mg co 3 2 shortite na 2 ca 2 co 3 3 nyerereite na 2 ca co 3 2 zemkorite na k 2 ca co 3 2 and fairchildite k 2 ca co 3 2 in addition to the dominant carbonates the melt inclusions contain phosphates chlorides and sulphates bradleyite na 3 mg po 4 co 3 halite sylvite aphthitalite na 0 25 k 0 75 2 so 4 but the silicate component is represented by tetraferriphlogopite only the melt inclusions in olivine studied in heating experiments show immiscibility of two carbonate liquids on heating and cooling and homogenise at low temperature 2 o sro and bao in wt 0 37 0 65 1 17 2 40 2 37 4 18 respectively such compositions are compared to secondary calcite replacing nyerereite and shortite in the natrocarbonatite lavas of the modern oldoinyo lengai volcano the results on mineralogy composition and homogenisation temperature of melt inclusions and the groundmass of the koala kimberlite imply that the parental kimberlite liquid was a si poor ca mg carbonate enriched in alkali elements lithophile trace elements phosphorus chlorine and sulphur

tangential stress beneath wind driven air water interfaces the detailed structure of the aqueous surface sublayer flow immediately adjacent to the wind driven air water interface is investigated in a laboratory wind wave flume using particle image velocimetry piv techniques the goal is to investigate quantitatively the character of the flow in this crucial very thin region which is often disrupted by microscale breaking events in this study we also examine critically the conclusions of okuda kawai toba 1977 who argued that for very short strongly forced wind wave conditions shear stress is the dominant mechanism for transmitting the atmospheric wind stress into the water motion waves and surface drift currents in strong contrast other authors have more recently observed very substantial normal stress contributions on the air side the availability of piv and associated image technology now permits a timely re examination of the results of okuda et al which have been influential in shaping present perceptions of the physics of this dynamically important region the piv technique used in the present study overcomes many of the inherent shortcomings of the hydrogen bubble measurements and allows reliable determination of the fluid velocity and shear within 200 m of the instantaneous wind driven air water interface the results obtained in this study are not in accord with the conclusions of okuda et al that the tangential stress component dominates the wind stress it is found that prior to the formation of wind waves the tangential stress contributes the entire wind stress as expected with increasing distance downwind the mean tangential stress level decreases marginally but as the wave field develops the total wind stress increases significantly thus the wave form drag represented by the difference between the total wind stress and the mean tangential stress also increases systematically with wave development and provides the major proportion of the wind stress once the waves have developed beyond their early growth stage this scenario reconciles the question of relative importance of normal and tangential stresses at an air water interface finally consideration is given to the extrapolation of these detailed laboratory results to the field where the present findings suggest that the sea surface is unlikely to become fully aerodynamically rough at least for moderate to strong winds

spectral evolution of nearshore wave energy during a sea breeze cycle abstractfrom in situ measurements taken over several sea breeze cycles off a beach in southwest sw australia the evolution of the one dimensional spectrum of wave energy is observed to have a distinctive spectral shape during the land breeze phase of the cycle lower rates of dissipation of wave energy are seen at high frequencies compared to midrange frequencies above the remnant wind sea peak a simulation of waves was performed using the simulating waves nearshore swan model and produced the same spectral evolution by generating longshore modes as seen in the observations the performance of whitecapping schemes available in swan was assessed and the alves banner scheme was found to best simulate the observed growth and decay of the wave spectra during the onshore phase of the sea breeze cycle local wave growth is duration limited and during the offshore land breeze phase wave growth is fetch limited from an examination of the modeled two dimensional spectra it is found that quadruplet in

the free surface turbulent shear layer abstract in applying the wall layer analogy to a wind blown free surface it is necessary to decide in what coordinate system such an anology is realistic a smoothed sea surface is taken to be that produced by the nearly irrotational components of the wave field relegating irregular dissipative wavelets to turbulence it is then possible to regard wave motion and shear flow as independent except for the vortex force effect of stokes drift discussed by leibovich an analysts or the available observations shows that the free surface shear layer has many of the characteristics of the wall layer a major difference is a much larger roughness parameter arising presumably from direct energy input to surface turbulence by the wind velocity gradients near the free surface are much smaller then over a solid wall under otherwise comparable conditions

prograde and retrograde fluid flow during contact metamorphism of siliceous carbonate rocks from the ballachulish aureole scotland siliceous dolomites and limestones contain abundant retrograde minerals produced by hydration carbonation reactions as the aureole cooled marbles that contained periclase at the peak of metamorphism bear secondary brucite dolomite and serpentine forsterite dolomite marbles have retrograde tremolite and serpentine wollastonite limestones contain secondary calcite and quartz and wollastonite free limestones have retrograde tremolite secondary tremolite never appears in marbles where brucite has replaced periclase or in wollastonite bearing limestones a model for infiltration of siliceous carbonates by co2 h2o fluid that assumes a vertical upwardly directed flow b fluid flux proportional to cooling rate and c flow and reaction under conditions of local equilibrium between peak temperatures and 400 c reproduces the modes of altered carbonate rocks observed reaction textures and the incompatibility between tremolite and brucite and between tremolite and wollastonite except for samples from a dolomite xenolith retrograde time integrated flux recorded by reaction progress is on the order of 1000 mol fluid cm2 rock local focusing of flow near the contact is indicated by samples from the xenolith that record values an order of magnitude greater formation of periclase forsterite and wollastonite at the peak of metamorphism also required infiltration with prograde time integrated flux approximately 100 1000 mol cm2 the comparatively small values of prograde and retrograde time integrated flux are consistent with lack of stable isotope alteration of the carbonates and with the success of conductive thermal models in reproducing peak metamorphic temperatures recorded by mineral equilibria although isobaric univariant assemblages are ubiquitous in the carbonates most formed during retrograde metamorphism isobaric univariant assemblages observed in metacarbonates from contact aureoles may not record physical conditions at the peak of metamorphism as is commonly assumed

spatial evolution of young wind waves numerical modelling verified by experiments a numerical model that allows one to study numerically the evolution of waves along the test section of a wind wave tank is offered the simulations are directly related to wind wave tank experiments carried out for a range of steady wind velocities at each wind forcing condition the evolving wind wave field is strongly non homogeneous with wave energy growth along the test section accompanied by frequency downshifting the wave parameters measured at a short fetch serve as a basis for generating numerous realizations of the initial conditions in the monte carlo numerical simulations the computations are based on a modified unidirectional spatial version of the zakharov equation that accounts for wind input and dissipation and is applicable for the whole range of wind velocities employed the model contains two empirical parameters that are selected by comparison of the experimental and numerical results the same values of those parameters are applied for all wind forcing conditions the availability of an experimentally verified numerical model allows one to study the contributions of nonlinear wave wave interactions dissipation and wind input separately special attention is given to accounting for the three dimensional and random nature of wind waves as observed in experiments the suggested model combines approaches adopted in the wind wave growth theories by miles and phillips

mineralogy of primary carbonate bearing hypabyssal kimberlite lac de gras slave province northwest territories canada abstract a suite of fresh late cretaceous to eocene hypabyssal kimberlites from the lac de gras field were studied in order to understand better carbonate silicate and oxide paragenesis the samples have excellent preservation of textures and primary mineralogy and are archetypal or group 1 kimberlite five kimberlite localities are identified as calcite bearing based on the presence of high sr ba calcite as phenocrysts microphenocrysts and in segregations three kimberlite localities are identified as dolomite bearing based on the presence of mixed calcite dolomite segregations containing oscillatory and banded textures of calcite dolomite solid solution and dolomite magnesite sr ba calcite are characterized by high xca 0 95 and are enriched in sr 4900 11 100 ppm and ba 3200 14 200 ppm the calcite dolomite and dolomite magnesite solid solution compositions span the xca range from 0 42 to 0 95 and typically have sr and ba contents in the range of 1000 4000 ppm the carbonate silicate and oxide mineral compositions suggest that the origin of the calcite bearing versus dolomite bearing kimberlites studied is related to subtle differences in parent magma composition in particular the co2 h2o ratio formation of the carbonates reflects the latter part of a protracted magmatic crystallization sequence in which sr ba calcite precipitates from an evolved kimberlite melt subsequently calcite dolomite solid solution and dolomite is precipitated from localized mg rich carbonate fluids at relatively high temperatures higher than serpentine stability

statistical analysis of the spatial evolution of the stationary wind wave field detailed investigation of wind generated water waves in a 5 m long wind wave flume facility is reported careful measurements were carried out at a large number of locations along the test section and at numerous airflow rates the evolution of the wind wave field was investigated using appropriate dimensionless parameters when possible quantitative comparison with the results accumulated in field measurements and in larger laboratory facilities was performed particular attention was given to the evolution of wave frequency spectra along the tank distinguishing between the frequency domain around the spectral peak and the highfrequency tail of the spectrum notable similarity between the parameters of the evolving wind wave field in the present facility and in field measurements was observed

composition and emplacement of the benfontein kimberlite sill complex kimberley south africa textural petrographic and melt inclusion constraints abstract the benfontein kimberlite is a renowned example of a sill complex and provides an excellent opportunity to examine the emplacement and evolution of intrusive kimberlite magmas we have undertaken a detailed petrographic and melt inclusion study of the benfontein upper middle and lower sills these sills range in thickness from 0 25 to 5 m new perovskite and baddeleyite u pb dating produced ages of 85 7 4 4 ma and 86 5 2 6 ma respectively which are consistent with previous age determinations and indicate emplacement coeval with other kimberlites of the kimberley cluster the benfontein sills are characterised by large variations in texture e g layering and mineral modal abundance between different sill levels and within individual samples the lower sill is characterised by carbonate rich diapirs which intrude into oxide rich layers from underlying carbonate rich levels the general paucity of xenogenic mantle material in the benfontein sills is attributed to its separation from the host magma during flow differentiation during lateral spreading the low viscosity is likely responsible for non explosive emplacement of the benfontein sills while the rhythmic layering is attributed to multiple magma injections the benfontein sills are marked by the excellent preservation of olivine and groundmass mineralogy which is composed of monticellite spinel perovskite baddeleyite ilmenite apatite calcite dolomite along with secondary serpentine and glagolevite namg6 si3alo10 oh o 8 h2o this is the first time glagolevite is reported in kimberlites groundmass spinel exhibits atoll textures and is composed of a magnesian ulvospinel magnetite mum or chromite core surrounded by occasional pleonaste and a rim of mg al magnetite we suggest that pleonaste crystallised as a magmatic phase but was resorbed back into the residual host melt and or removed by alteration analyses of secondary inclusions in olivine and primary inclusions in monticellite spinel perovskite apatite and interstitial calcite are largely composed of ca mg carbonates and to a lesser extent alkali carbonates and other phases these inclusions probably represent the entrapment of variably differentiated parental kimberlite melts which became progressively more enriched in carbonate alkalis halogens and sulphur during crystal fractionation carbonate rich diapirs from the lower sill contain more exotic phase assemblages e g ba fe titanate barite ancylite pyrochlore which probably result from the extreme differentiation of residual kimberlite melts followed by physical separation and isolation from the parental carbonate rich magma it is likely that any alkali or halogen rich minerals crystallising in the groundmass were removed from the groundmass during syn post magmatic alteration or in the case of na remobilised to form secondary glagolevite the benfontein sill complex therefore provides a unique example of how the composition of kimberlites may be modified after magma emplacement in the upper crust

observations of typhoon waves in a reef lagoon of the south china sea abstractbased on wave measurements lasting three and a half years typhoon wave characteristics in a lagoon of the south china sea are discussed in this paper according to the upper boundaries of

x band sea surface coherence time inferred from bistatic sar interferometry coherence time plays an important role in ocean surface observation by means of synthetic aperture radar sar for x band the autocorrelation function acf of the backscatter from the sea surface has been predicted using models up to now there exist only few experimental data and an empirical analysis of the sea surface coherence time based on a larger amount of data is missing in this paper we show how space based bistatic sar along track interferometry is used for the first time to measure the acf we achieve this by statistical analysis of the interferometric scene coherence as a function of the along track interferometric time lag instead of indirect estimation from the doppler bandwidth we use many data acquisitions of opportunity for that purpose thereby exploiting the diversity of along track baselines between the two sar sensors of the tandem x satellite formation the acf is related to the temporal decorrelation which is not directly observable we extract this component by quantifying and compensating for all other sources of decorrelation that contribute to the observed coherence

near surface measurements of quasi lagrangian velocities in open water abstract near surface water velocities have been measured in the coastal zone of lake huron and cape cod bay by tracking drifters and drogues using acoustic travel time and compass sighting techniques the near surface current defined as the velocity of near surface drifters and drogues relative to a drogue set at 1 8 m varied on the depth scale on the order of 1 m and was directed nearly parallel to the wind and to predominant wave propagation velocity velocity profiles were logarithmic with depth to order 1 m depth and realistic values of stress were calculated using a law of the wall formula and a karman s constant of 0 4 inferred roughness lengths were of the order of 30 cm anomalously high values of wind stress were inferred from velocity profiles observed during conditions of light wind and steady swell these may be due to the similarity of stokes drift distribution to turbulent shear flow profiles

metal binding to dissolved organic matter and adsorption to ferrihydrite in shallow peat groundwaters application to diamond exploration in the james bay lowlands canada the speciation and solubility of kimberlite pathfinder metals ni nd ba and k in shallow peat groundwaters is investigated over the yankee zulu and golf kimberlites in the attawapiskat region james bay lowlands canada the purpose of this study is to examine the relationship between dissolved organic matter dom complexation with kimberlite pathfinder metals and determine the spatial distribution of those metals in shallow peat groundwaters along sampling transects over subcropping kimberlites nickel nd ba and k complexation with dom and the adsorption of these metals onto ferrihydrite were calculated using visual minteq 3 0 and the nica donnan database calculations predict almost 100 of soluble nd ni and ba form complexes with dom at sampling sites with little to no contribution from upwelling groundwater i e dissolved organic c doc concentrations 40 132 mg l ph 3 9 5 5 and log ionic strength 6 3 in only the most ombrotrophic peat groundwater conditions does a majority fraction of k bind to dom by contrast under conditions with large contributions from upwelling groundwaters i e doc concentrations 640 mg l ph 5 5 6 5 and log ionic strength 3t o 2 as little as 10 of nd and ni and 0 k and ba are predicted to complex with dom the modeling calculations suggest the dominant control on metal dom complexation particularly with respect to ni and nd is competitive effects for dom binding sites due to elevated ionic strength where there is evidence of strong groundwater upwelling visual minteq modeling of metal adsorption on ferrihydrite surfaces predicts that under strong upwelling conditions ni and nd are scavenged from solution due to increased ferrihydrite precipitation and decreased fractions of metals complexed with dom analytical geochemical data are consistent with model predictions of metal adsorption on ferrihydrite total dissolved ni and nd concentrations at sites of strong upwelling are up to five times lower than waters with little to no upwelling and log ferrihydrite saturation indices logsi ferr indicate precipitation values up to 5 at sites of strong groundwater upwelling where the majority of ni and nd complex with dom and ferrihydrite is highly under saturated logsiferr 18 to 5 the concentrations of total ni and nd are elevated compared to other sites along sampling transects metal complexation with dom effectively inhibits metal scavenging from solution via adsorption and or from forming secondary mineral precipitates also because alkaline earth metals do not compete strongly with ni and nd for adsorption sites on ferrihydrite surfaces but do compete strongly for insoluble organic sites ni and nd are more likely to adsorb onto ferrihydrite

a review of the structure petrology and dynamic deformation characteristics of some enigmatic terrestrial structures abstract we review three categories of enigmatic terrestrial structures that have a variety of macroscopic and microscopic dynamic deformation features the first category includes the midcontinent united states cryptoexplosion structures they are of shallow origin and illustrate the effects that might be expected from a meteorite impact on a sedimentary rock terrane the second category includes the well known vredefort and sudbury plutons or basement uplifts the lesser known precambrian basement uplifts at steen river manson and carswell and the diatreme breccia dikes at the slate islands they are of relatively deep seated origin and illustrate the effects that might be expected from deep crustal or mantle processes of an explosive nature the third category includes the large landslides in areas of crystalline rocks at koefels and langtang the dynamic deformation features at these latter locations appear to be related to high strain rate tectonic processes associated with the landslide itself we conclude that microscopic dynamic deformation features which occur in natural materials may have originated from meteorite impacts from internal explosions or from high strain rate tectonic process

alteration styles in the orion central volcanic complex fort a la corne kimberlite field saskatchewan and their effects on primary volcaniclastic textures implications for facies mapping and diamond exploration diamond grade distributions within individual kimberlite bodies are controlled by physical emplacement processes which are generally determined from volcaniclastic facies characteristics however the effects and distribution of secondary alteration styles which usually mask primary kimberlite facies have been given little attention at the fort a la corne kimberlite field saskatchewan complex overprinting alteration textures and mineral phases are recognized this study documents the characteristics overprinting relationships and spatial distribution of alteration styles within a crater filling volcaniclastic deposit body 219 of the orion central volcanic complex data were acquired from macroscopic drill core observations microscopic petrography sem imaging eds element mapping and xrd analyses olivine crystals display a mesh fracture pattern and have been replaced by multiple generations of serpentine and magnetite late stage serpentine has migrated into the interstitial medium bulk rock alteration textures include 1 fine grained crystal rich domains which are alteration pseudoclasts and or relict juvenile pyroclasts 2 a heterogeneous interstitial medium varying from early stage disseminated calcite rich serpentine to amorphous serpentine and crystalline calcite and 3 overprinting serpentine carbonate and magnetite veins and serpentine nodules alteration styles defined by unique alteration characteristics are spatially zoned through the body 219 volcaniclastic deposit and this is a result of multiple reaction fronts associated with the influx of fluids of varying composition over time and permeating different parts of the deposit recognition of alteration processes their paragenesis and spatial controls can assist in defining and constraining the distribution of primary kimberlite facies and by consequence the distribution of diamond grades

oceanic turbulence dissipation measurements in swade abstract recent experiments measuring turbulence dissipation rates in the upper ocean can be divided into two types those supporting an analogy between the upper ocean and lower atmosphere with dissipation rates following wall layer behavior and those finding oceanic dissipation rates to be much higher than wall layer predictions in an attempt to reconcile these two diverse acts of observations terray et al proposed a wave dependent scaling of the dissipation rate based on the significant wave height and the rate of energy input from the wind to the waves their parameterization was derived from observations of strongly forced fetch limited waves although they conjectured that it would apply in typical oceanic conditions as well this paper reports new measurements of turbulent kinetic energy dissipation made in the north atlantic ocean from a swath ship during the recent surface waves dynamics experiments swade these data support the scaling of terray et al verifying its validity when applied

a physical model of sea wave period from altimeter data a physical model for sea wave period from altimeter data is presented physical roots of the model are in recent advances of the theory of weak turbulence of wind driven waves that predicts the link of instant wave energy to instant energy flux to from waves the model operates with wave height and its spatial derivative and does not refer to normalized radar cross section 0 measured by the altimeter thus the resulting formula for wave period does not contain any empirical parameters and does not require features of particular satellite altimeter or any calibration for specific region of measurements a single case study illustrates consistency of the new approach with previously proposed empirical models in terms of estimates of wave periods and their statistical distributions the paper brings attention to the possible corruption of dynamical parameters such as wave steepness or energy fluxes to from waves when using the empirical approaches applications of the new model to the studies of sea wave dynamics are discussed

the influence of buried kimberlite on methane production in overlying sediment attawapiskat region james bay lowlands ontario abstract shallow groundwaters were collected over and near buried kimberlites in the attawapiskat river region of the james bay lowlands ontario canada in order to study the impact kimberlites have on co 2 ch 4 systematics groundwaters collected from boreholes in kimberlites and limestone and from groundwaters in overlying tyrell sea sediment tss were analyzed for 13 c dic 2 h h2o 18 o h2o dissolved inorganic carbon dic and metal concentrations methane gas samples from borehole and tss groundwaters were analyzed for concentration 13 c ch4 and 2 h ch4 the ch 4 concentrations and 13 c dic ch4 isotope separation values indicate biological carbonate reduction in tss groundwaters overlying kimberlites whereas 13 c dic ch4 values from tss groundwaters over limestone and from boreholes within limestone and kimberlite indicate the biological consumption of methane oxidation the 2 h h2o values from tss over kimberlites are consistent with the variation in 13 c dic ch4 as they are less negative compared to where they should fall on the local meteoric water line suggesting that methanogens are using lighter 2 h h2o values to produce ch 4 biological dic reduction requires h ions from h 2 o to form ch 4 there is evidence in the water geochemistry to support the isotopic results as the ratio of methane to calculated fe 3 as amorphous fe hydroxide so 4 2 and o 2 aq is largest in the majority of tss groundwaters over kimberlites where 13 c dic ch4 values indicate ch 4 production low temperature serpentinization of olivine in kimberlite is not considered for ch 4 production as redox conditions in kimberlite groundwaters do not support abiogenic methane production the findings here suggest that kimberlites are indirectly influencing the co 2 ch 4 system by consuming oxidized ions in the overlying tss thereby creating a favorable environment for methane producing bacteria in contrast isotopes and geochemistry suggest methane oxidation in areas overlying limestone the broader implication of this study is that variable lithology underlying sediment cover may impact biological methane production or consumption

controls on the explosive emplacement of diamondiferous kimberlites new insights from hypabyssal and pyroclastic units in the diavik mine canada abstract kimberlites are mantle derived magmas that either crystallise as hypabyssal intrusions erupt explosively after rapid ascent to the surface or less commonly form lava lakes and flows thereby creating texturally distinct kimberlite units efforts to fully understand the processes responsible for the explosive eruption of kimberlite magmas have been hindered by the widespread alteration and crustal contamination of most volcaniclastic kimberlites to address this issue we have undertaken a detailed petrographic and mineral chemical study of fresh i e minimally altered pyroclastic and hypabyssal kimberlites hk from the ca 55 56 ma a154 north and south kimberlite pipes in the diavik mine lac de gras canada these localities host exceptionally fresh kimberlites and are therefore ideally suited to this study kimberlite emplacement at a154 north and south initiated with the intrusion of hypabyssal kimberlite external dykes and was followed by the explosive formation of kimberlite pipes and volcaniclastic kimberlite infill subsequent kimberlite magmas intruded the volcaniclastic kimberlite units forming multiple cross cutting internal dykes the studied volcaniclastic units feature abundant rounded magmaclasts and massive textures suggestive of primary deposits these units are classified as pyroclastic kimberlites pk pyroclastic and hypabyssal kimberlite units at diavik exhibit subtle mineral compositional differences samples from both internal hk units and pk units feature identical compositions for liquidus olivine rims mg 90 5 0 1 and 90 7 0 2 respectively with a marginally lower mg of 90 2 0 2 in olivine rims from the external hk dykes similarly early formed chromite compositions are the same for internal hk and pk units cr 79 1 3 4 and 78 3 5 7 mg 60 0 1 3 and 60 0 2 2 but differ in the external hk units cr 86 9 2 7 mg 52 8 1 9 the internal hk and pk units also exhibit lower carbonate contents than the internal hk units these compositional differences indicate that the external dykes were probably derived from slightly different primitive melt compositions to those parental to the internal hk and pk units spinel evolutionary trends from chromite to magnesian ulv spinel magnetite mum compositions are indistinguishable in internal hk and pk samples fe3 47 2 5 8 and 49 7 9 3 cr 25 7 11 0 and 17 0 14 0 these results demonstrate that the primitive melt compositions and early magmatic evolution processes are identical for the internal kimberlite units regardless of whether the kimberlite melts erupted explosively or were emplaced as shallow intrusions however magmaclasts in the pk units contain higher abundances of phlogopite

recent developments in the study of ocean turbulence abstract this review describes the changes in the understanding of turbulence and mixing in the upper layers of the ocean the abyssal ocean and in continental shelf seas that have come in the past 25 years largely through advances in instruments and methodology

the origin of high hydrogen content in kimberlitic olivine evidence from hydroxyl zonation in olivine from kimberlites and mantle xenoliths abstract olivine macrocrysts in kimberlites are the most h rich natural olivines known their xenocrystic provenance makes unclear whether h enrichment occurred in the mantle prior to entrainment in kimberlite magma or during ascent we present a fourier transform infrared ftir spectroscopy based study of h zonation in kimberlite derived olivine macrocrysts and or olivine in xenoliths from the kimberlites jericho nunavut canada beartooth northwest territories canada and pipe 200 and matsoku lesotho the objective of the study was to determine whether changes in the concentration or speciation of h defects in proximity to the host kimberlite could yield insights into the origin of h enrichment within the group 1 region of the ftir spectrum 3420 3700 cm 1 we find that olivines within xenoliths and macrocrysts show weak zonation or significant h depletions in rims peaks in the group 2 region 3260 3420 cm 1 in beartooth olivines show marked decrease in the crystal margins in comparison to group 1 peaks we find no preserved evidence for kimberlite related h enrichment in our dataset we ascribe h depletion to diffusive h loss to infiltrating kimberlitic media diffusion models using coefficients previously applied to dehydrogenation of olivine and assuming a dry environment produce extremely short ascent durations incompatible with the results of other geospeedometers this mismatch suggests that the poorly developed zonation in jericho and beartooth olivines indicates water enrichment and or faster ascent of these melts in comparison to pipe 200 and matsoku resulting in greater retention of mantle derived h a further significant factor in the mismatch is the differing speciation of h in most natural mantle derived olivines in comparison to those used in diffusion experiments we argue that the presence of presumably mantle derived group 2 h in olivine macrocrysts indicates rapid ascent of magma exsolving water rich fluid permitting preservation of these faster diffusing defects only in particularly rapidly ascending kimberlite magmas this interpretation explains empirical correlations between the presence of group 2 bands water derived diamond resorption features and volcaniclastic kimberlite facies

impact of swell on the marine atmospheric boundary layer a model that describes the impact of swell on the marine atmospheric boundary layer is proposed the model is based on the two layer approximation of the boundary layer the near surface inner region and the outer region above the swell induced momentum and energy fluxes are confined within the inner region swell loses energy to the atmosphere and enhances the turbulent kinetic energy in the inner region the transfer of momentum results in acceleration or deceleration of the airflow near the surface following wind swell accelerates the flow which for a very low wind results in a swell driven wind opposite wind swell decelerates the airflow which for a steep swell could cause the reverse airflow the sea drag in the case of opposite wind swell is considerably enhanced as compared with the following wind swell case cross wind swell causes the rotation of the wind velocity vector with height which leads to the deviation of the turbulent stress vector from the wind velocity vector the impact of swell becomes more pronounced when the wind speed decreases or when the swell phase velocity increases in fact it is the wave age of the swell that characterizes the swell impact because the dimensionless wave induced fluxes of energy and momentum are proportional to the wave age parameter both fluxes are also proportional to the swell slope so that the swell impact is stronger for a steeper swell the model reproduces qualitatively and quantitatively the main experimental findings for the ocean swell the impact of swell on the sea drag is very pronounced for opposite wind swell is less pronounced for cross wind swell and is only at low wind speeds

polymineralic inclusions in kimberlite hosted megacrysts implications for kimberlite melt evolution abstract megacrysts are large cm to 20 cm in size mantle derived crystals which are commonly entrained by kimberlite magmas comprising of olivine orthopyroxene clinopyroxene phlogopite garnet ilmenite and zircon as common phases numerous studies have shown megacrysts to contain polymineralic inclusions which have been interpreted to represent entrapped kimberlite melt to constrain the origin of these inclusions in megacrysts and their relationship to kimberlite magmatism we present a detailed petrographic and geochemical study of clinopyroxene and olivine megacrysts and their hosted inclusions from the diavik jericho leslie slave craton canada and udachnaya east siberian craton russia kimberlites the studied megacrysts are between 1 and 3 cm in size and representative of both the cr rich and cr poor suites megacrysts contain two types of inclusions i large ii swarms trails of micro melt inclusions mmi textural and geochemical evidence suggests that polymineralic inclusions in megacrysts crystallised from kimberlite melt which infiltrated along fracture vein networks the polymineralic inclusion assemblages resulted from disequilibria reactions between the host megacryst and infiltrating kimberlite melt which was likely enhanced by rapidly changing conditions during magmatic ascent the connectivity of polymineralic inclusions to the kimberlite groundmass via network veins fractures suggests that they are susceptible to infiltrating post emplacement fluids therefore the vast majority of polymineralic inclusions are unlikely to represent pristine entrapped kimberlite melt in contrast mmis are isolated within megacrysts i e not connected to fractures veins and therefore shielded from post magmatic fluids and probably represent entrapped remnants of the variably differentiated kimberlite melt which was more enriched in alkalis cl s co2 than serpentinised polymineralic inclusions and the host rocks exposed at earth s surface as kimberlites

validation of hf radar probing of the vertical shear of surface currents by acoustic doppler current profiler measurements 1 there exists no practical way of measuring vertical shear in the water just below the air sea interface that contains information on air water momentum fluxes the paper is concerned with the validation of a recently proposed method of remote sensing of sea subsurface shear by means of a commonly used single frequency hf radar based on the use of the second order bragg echo to this end a dedicated field experiment was carried out off the french mediterranean coast in parallel with the hf radar probing the independent simultaneous measurements of the subsurface shear profile were obtained by means of acoustic doppler current profiler mounted on a floating platform whose position was monitored by gps the comparison shows a fairly good agreement of the results the discrepancy does not exceed 15 and suggests a higher accuracy of the hf probing

two faces of enso induced surface waves during the tropical cyclone season abstract the response of the wave climate to tropical cyclones tcs is investigated using the significant wave height swh observed from satellites and the wavewatch iii ww3 model tropical cyclone wind generates local waves wind seas under the tc and longer period waves swells that propagate long distances the genesis location intensity and frequency of tropical cyclones over the global ocean are strongly affected by the phases of the el nino southern oscillation enso it is shown that the interannual variation of global ocean surface waves in the subtropics during summer is dominated by enso related tc activity in particular in the subtropical western north pacific the wind power is stronger in the tc season before an el nino and weaker before a la nina these enso related tc variations are shown through composite and empirical orthogonal function analyses as well as modeling to dominate the spatial distribution and temporal variation of the swh over the western north pacific the model confirms that longer period waves swells are driven into northern south china sea toward japan in mid latitudes and toward the central pacific along the equator due to enso related tc activities the wind power and swh over the subtropical western north pacific lead and regress well with the enso index suggesting that they may potentially serve as useful enso predictors

fetch and duration limited nature of surface wave growth inside tropical cyclones with applications to air sea exchange and remote sensing abstractthe 2d wavenumber spectra collected by an airborne scanning radar altimeter in hurricane hunter missions are used to investigate the fetch and duration limited nature of wave growth inside hurricanes despite the much more complex wind forcing conditions the dimensionless growth curves obtained with the wind wave triplets reference wind velocity significant wave height and dominant wave period inside hurricanes except near the eye region are comparable to the reference similarity counterparts constructed with the wind wave triplets collected in field experiments conducted under ideal quasi steady fetch limited conditions in dimensionless terms the youngest waves are in the back quarter of the hurricane in the northern hemisphere the dimensionless frequency decreases systematically counterclockwise ccw and the most mature waves are in the left hand sector except for those waves near the eye region the dominant wave phase speeds are about 0 32 to 0 71 times of the local wind speed

dimensionally consistent similarity relation of ocean surface friction coefficient in mixed seas abstractapplying wavelength scaling dimensionally consistent expressions of the ocean surface friction coefficient can be developed for both wind sea and mixed sea in the ocean for a wind sea with a monopeak wave spectrum the natural choice of the scaling wavelength is that of the spectral peak component for a mixed sea with a multipeak spectrum the peak component in the wind sea portion of the wave spectrum is not a good reference wavelength a much better scaling wavelength is the weighted average of swell and wind sea following the consideration of equivalent momentum in the wave field the resulting friction coefficient c 2 is referenced to the wind speed at one half of the scaling wavelength u 2 instead of c10 referenced to the neutral wind speed at 10 m elevation u10 although referencing the wind speed at a fixed elevation such as u10 is of practical necessity u 2 is physically significant as the free stream velocity in wave modulated boundary layer flows a simple procedure to apply the s

dynamic deformation of volcanic ejecta from the toba caldera possible relevance to cretaceous tertiary boundary phenomena plagioclase and biotite phenocrysts in ignimbrites erupted from the toba caldera sumatra show microstructures and textures indicative of shock stress levels higher than 10 gpa strong dynamic deformation has resulted in intense kinking in biotite and with increasing shock intensity the development of plagioclase of planar features shock mosaicism incipient recrystallization and possible partial melting microstructures in quartz indicative of strong shock deformation are rare however and many shock lamellae if formed may have healed during post shock residence in the hot ignimbrite they might be preserved in ash falls peak shock stresses from explosive silicic volcanism and other endogenous processes may be high and if so would obviate the need for extraterrestrial impacts to produce all dynamically deformed structures possibly including shock features observed near the cretaceous tertiary boundary 38 references 3 figures

reduction of wind stress due to swell at high wind conditions 1 wind stress over the ocean depends on the sea surface roughness which is determined by the sea state on one hand underdeveloped wind seas rougher than their fully developed counterpart increase the drag on the other hand the presence of swell can modify wind stress by modifying the wind sea roughness this latter mechanism is believed to have a great impact at high winds whenever underdeveloped local waves coexist with swell detailed measurements of wind stress and wavefield in fetch limited growth conditions were made in an area subjected to strong and persistent winds through the analysis of wavefield observations it is found that the presence of swell dampens the short wind waves the observed attenuation is greater for younger wind seas and decreases as the wind waves become older results obtained from modeling the interaction of wind waves and the air flow above point out that the attenuation of short wind waves causes a reduction of the wave supported stress which in turn decreases the total wind stress

statistical properties of mechanically generated surface gravity waves a laboratory experiment in a three dimensional wave basin a wave basin experiment has been performed in the marintek laboratories in one of the largest existing three dimensional wave tanks in the world the aim of the experiment is to investigate the effects of directional energy distribution on the statistical properties of surface gravity waves different degrees of directionality have been considered starting from long crested waves up to directional distributions with a spread of 30 at the spectral peak particular attention is given to the tails of the distribution function of the surface elevation wave heights and wave crests comparison with a simplified model based on second order theory is reported the results show that for long crested steep and narrow banded waves the second order theory underestimates the probability of occurrence of large waves as directional effects are included the departure from second order theory becomes less accentuated and the surface elevation is characterized by weak deviations from gaussian statistics

reynolds stresses under wind waves this paper describes a series of wave measurements taken from an oceanographic tower concerning water particle kinematics attention is focused on the phase relationship between surface elevation and the velocity components large phase shifts with respect to the expected values are found under active wave conditions while swell behavior closely follows the linear theory the reliability of the measurements is analyzed in detail possible physical reasons for the findings are indicated in the final discussion

mineralogy of fine grained rims in the alh 81002 cm chondrite abstract the mineralogy of fine grained rims in alh 81002 a relatively primitive cm carbonaceous chondrite has been determined by using transmission electron microscopy the most abundant phase is mg rich serpentine which occurs in small 20 nm crystals with cylindrical or fibrous morphologies cronstedtite an fe rich phyllosilicate occurs as relatively large 100 to 2500 nm platy crystals some cronstedtite is coherently intergrown with tochilinite in many cases cronstedtite has been partially altered to serpentine the compositions and textures of these two phases provide a mineralogical and morphologic alteration sequence that parallels the known compositional trend for cm chondrite matrix accessory minerals embedded within the phyllosilicates include chlorite pentlandite gypsum olivine kamacite taenite and chromite regions containing only anhydrous minerals also occur the hydrated and anhydrous regions are in direct contact with each other suggesting that the rims accreted material from multiple reservoirs

pre ore hydrothermal alteration in an unconformity type uranium deposit hydrothermal alteration associated with the formation of unconformity type uranium deposits is manifested mainly by intense chloritic replacement of metamorphic mineral assemblages at the koongarra deposit northern australia three stages of pre ore alteration were identified in chloritized metamorphic muscovite using optical microscopy the electron microprobe and transmission and analytical electron microscopy tem and aem during the first stage metamorphic muscovite was altered to a mica with very low interlayer occupancy k content as low as 0 35 compared to 1 for ideal muscovite high octahedral cation content up to 2 3 whereas ideal muscovite has 2 and high si content high resolution tem images show that these changes in composition were accompanied by frequent layer terminations in contrast to the metamorphic muscovite whereas selected area electron diffraction patterns indicate that the altered muscovite remained a two layer polytype the alteration of muscovite appears more extensive in the outer alteration halo and has been almost completely eradicated in the ore zone where chloritization is more complete during the second stage of the pre ore alteration the altered muscovite was replaced by mg rich serpentine lizardite and clinochlore high resolution tem images show two 10 a mica layers coalescing to one 14 a chlorite layer this type of coalescence appears to involve transformation of one dioctahedral layer of the mica structure to one trioctahedral brucite layer in the chlorite structure through dissolution of the tetrahedral sheets and cation influx in the octahedral site the final stage of the pre ore alteration resulted in replacement of lizardite and clinochlore by fe rich chlorite comparison of the alteration observed in metamorphic muscovite with the alteration observed in metamorphic biotite and garnet shows clearly that chloritization of these phases was also a pre ore alteration event pre ore alteration was principally characterized by the evolution of chlorite from a mg rich phase to an ferich one

characterization of turbulent airflow over evolving water waves in a wind wave tank 1 results of an experimental investigation of the turbulent boundary layer in airflow over evolving young wind waves are presented the experiments were conducted in a laboratory wind wave flume consisting of a closed loop wind tunnel capable of generating wind speed that may exceed 15 m s atop of a 5 m long wave tank simultaneous measurements of mean wind velocity and of instantaneous fluctuations of the horizontal and vertical air velocity components were carried out along the test section at different airflow rates and at numerous heights above the highest wave instantaneous surface elevation at the air sensors location was simultaneously recorded the friction velocities at all locations and for all airflow rates were determined by two independent methods by fitting the logarithmic velocity profiles and by extrapolating the measured reynolds shear stresses to mean water surface level the variation with height and along the test section of the fluctuations of two velocity components in the mean flow and in the vertical directions was also studied and the results compared with flow behavior over rough and smooth plates wave induced airflow parameters were then investigated by application of cross spectral analysis results on the vertical extent of wave induced boundary layer on the phase relation between the wave induced velocity fluctuations and the surface elevation as well as on the wave induced reynolds shear stress are reported

diamond resorption features as a new method for examining conditions of kimberlite emplacement the study develops a new approach utilizing parameters of trigonal etch pits on diamond crystals to infer the conditions of diamond residence in kimberlite magma diamond crystals from dissolution experiments conducted at 1 gpa and 1150 1350 c in the presence of h2o rich or co2 rich fluid were studied with atomic force microscopy afm the afm data of resorbed diamond surfaces show that much deeper surface relief was produced in co2 fluid it also clearly distinguishes the profiles of the trigonal etch pits forming regular flat bottomed trigons in h2o fluid and round or pointed bottomed trigons in co2 fluid the relationship between the diameter and the depth of the trigonal pits is found to be another important indicator of the fluid composition dissolution in h2o fluid develops trigons with constant diameter and variable depth where the diameter increases with temperature trigons developed in co2 fluid have a large range of diameters showing a strong positive correlation with the depth the developed criteria applied to the natural diamond crystals from three ekati mine kimberlites indicate significant variation in co2 h2o ratio and temperature of their magmatic fluid this conclusion based on diamond resorption agrees with the mineralogy of microphenocrysts and groundmass of the studied kimberlites offering new method to study crystallization conditions of kimberlite magma

water waves excited by near impulsive wind forcing only limited information is currently available on the evolution of waves generated by wind that varies in time and in particular on the initial stages of wind wave growth from rest under a suddenly applied wind forcing the emerging wind wave field varies in time as well as in space detailed knowledge of wave parameter distributions under those conditions contributes to a better understanding of the mechanisms of wind wave generation in the present study the instantaneous surface elevation and two components of the instantaneous surface slope were recorded at various fetches in a small scale experimental facility under nearly impulsive wind forcing numerous independent realizations have been recorded for each selection of operational conditions sufficient data at a number of fetches were accumulated to calculate reliable ensemble averaged statistical parameters of the evolving random wind wave field as a function of the time elapsed from activation of wind forcing distinct stages in the wave evolution process from appearance of initial ripples to emergence of a quasi steady wind wave field were identified the experimental results during each stage of evolution were analysed in view of the viscous instability theory by kawai j fluid mech vol 93 1979 pp 661 703 and the resonance model by phillips j fluid mech vol 2 1957 pp 417 445

a rare occurrence of a crater filling clastogenic extrusive coherent kimberlite victor northwest ontario canada kimberlite pipes can contain significant proportions of dark and dense kimberlite that have mostly been interpreted as intrusive coherent hypabyssal in origin this study reports a well documented occurrence of a fresh intra crater clastogenic extrusive coherent kimberlite that is concluded to have formed as a result of lava fountaining this paper focuses on a dark dense competent generally crystal rich massive kimberlite unit within the victor northwest kimberlite pipe ontario canada using a comprehensive volcanological and petrographic analysis of all available drill cores it is shown that this unit has a fresh well crystallised coherent groundmass and is extrusive and pyroclastic in origin the proposed clastogenic coherent extrusive origin is based on deposit morphology gradational contacts to enveloping pyroclastic units as well as the presence of remnant pyroclast outlines and angular broken olivines this paper and an increasing number of other studies suggest that fragmental extrusive coherent kimberlite in intra crater settings may be more common than previously thought the emplacement history and volcanology of these pipes need to be reconsidered based on the emerging importance of this particular kimberlite facies

the effect of the degree of wave development on the sea state bias in radar altimetry measurement the effect of the degree of wave development on the sea state bias ssb in geosat altimeter height measurement is evaluated theoretical considerations suggest that the altimetric ssb is generally not a linear function of significant wave height but depends also on other factors of wave development of particular interest is its dependence on wave age defined as the ratio of the phase speed of the dominant ocean waves to ocean wind speed we estimate wave age rather crudely on the basis of the significant wave height h and wind speed measured by the altimeter under general conditions when the sea is not in equilibrium with the wind this estimate may not correspond to the wave age in a strict sense and hence is called pseudo wave age in this paper nevertheless the pseudo wave age is a rough indicator for the degree of wave development the general trend in the dependence of the ssb on pseudo wave age as found by analyzing 2 7 years worth of geosat data agrees well with the theoretical prediction for a given h the ssb decreases as the degree of the wave development measured by the pseudo wave age increases this empirical trend is modeled as ssb a m m h where and m are the pseudo wave age and its average value respectively a 0 013 0 005 and m 0 88 0 37 statistically this model performs slightly better than a standard model i e ssb h with being a constant in terms of the global rms error the improvement is by 1 6 cm however because the degree of wave development varies with the season and geographical location this small improvement could become important for more accurate altimetric missions in the future when the centimetric basin scale signals are the focus of the study

characteristics and alteration origins of matrix minerals in volcaniclastic kimberlite of the muskox pipe nunavut canada abstract the matrix of volcaniclastic kimberlite vk from the muskox pipe northern slave province nunavut canada is interpreted to represent an overprint of an original clastic matrix muskox vk is subdivided into three different matrix mineral assemblages that reflect differences in the proportions of original primary matrix constituents temperature of formation and nature of the altering fluids using whole rock x ray fluorescence xrf whole rock x ray diffraction xrd microprobe analyses back scatter electron bse imaging petrography and core logging we find that most matrix minerals serpentine phlogopite chlorite saponite monticellite fe ti oxides and calcite lack either primary igneous or primary clastic textures the mineralogy and textures are most consistent with formation through alteration overprinting of an original clastic matrix that form by retrograde reactions as the deposit cools or in the case of calcite by precipitation from ca bearing fluids into a secondary porosity the first mineral assemblage consists largely of serpentine phlogopite calcite fe ti oxides and monticellite and occurs in vk with relatively fresh framework clasts alteration reactions driven by deuteric fluids derived from the juvenile constituents promote the crystallisation of minerals that indicate relatively high temperatures of formation 400 c lower temperature minerals are not present because permeability was occluded before the deposit cooled to low temperatures thus shielding the facies from further interaction with fluids the other two matrix mineral assemblages consist largely of serpentine phlogopite calcite diopside and chlorite they form in vk that contains more country rock which may have caused the deposit to be cooler upon emplacement most framework components are completely altered suggesting that larger volumes of fluids drove the alteration reactions these fluids were likely of meteoric provenance and became heated by the volcaniclastic debris when they percolated into the vk infill most alteration reactions ceased at temperatures 200 c as indicated by the absence or paucity of lower temperature phases in most samples such as saponite recognition that muskox vk contains an original clastic matrix is a necessary first step for evaluating the textural configuration which is important for reconstructing the physical processes responsible for the formation of the deposit

on the welding of pyroclasts from very low viscosity magmas examples from kimberlite volcanoes abstract lithofacies in kimberlite pipes in southern africa exhibit features consistent with welded pyroclastic rocks these include flared conduit filling geometries abundant lithic clasts lithic clast layers subhorizontal clast fabrics gradational contacts with volcaniclastic rocks and sintered and coalesced globular ash and lapilli and melt coated particles the welding dynamics of kimberlite pyroclasts differ from those of glassy vesiculated pyroclasts in silicic volcanic systems low melt viscosity 0 1 pa s results in the efficient separation of volatiles and melt and the breakup of magma into nonvesicular spherical droplets the glassy state is difficult to form in silica deficient magmas because the crystallization kinetics are fast in low viscosity melts three pyroclastic lithofacies are recognized that primarily relate to the state of the initial melt phase in the pyroclasts on deposition 1 densely welded kimberlite forms where the initial melt phase in pyroclasts remains as pure mel

carbonatitic mineralogy of natural diamond forming fluids a suite of 20 cuboid fibrous diamonds from the democratic republic of congo was studied to determine mineral phases crystallized from diamond forming fluids that were trapped as inclusions in diamonds we identified minerals and non crystalline components using their compositional trends in the electron microprobe analyses of inclusions an innovative bulk x ray diffraction analysis and characteristic ftir and raman peaks the drc diamonds contain fluid inclusions of the ca carbonatitic silicic composition most common phases precipitated from the fluid are found to be high si micas 90 30 of the solids volume complex non crystalline na ca mg fe carbonate matter and apatite together 5 70 leaving a residual aqueous solution of k cl and carbonate ions and gaseous co2 a notable absence of carbonate minerals in bulk x ray diffraction patterns combined with the vibrational spectroscopy observations on the c o bonds indicates that c may be included in dissolved or amorphous carbonate matter the modes of the most abundant phases are controlled by chemical trends of the bulk fluid compositions other relatively rare 30 minerals including various minerals with structural and coordinated h2o are detected by the vibrational spectroscopic and x ray analyses the fluid also contains some hydrocarbons associated with the carbonate material the presence of some rare minerals and exotic compositions of solid solution minerals in the fluid suggest crystallization from a closed system with high salinity high ah2o high aco2 composition that persisted to relatively low temperatures and pressures the bulk of the fluid crystallized in the diamond stability field p 7 gpa t 950 c but continued to form hydrocarbons accessory and deuteric phases down to 200 c and 0 2 gpa overall the mineralogy of the fluid resembles carbonatite

the evolution of the onaping formation at the sudbury impact structure the 1 4 1 6 km thick onaping formation consists of a complex series of breccias and melt bodies lying above the sudbury igneous complex sic at the sudbury impact structure based on the presence of shocked lithic clasts and various glassy phases the onaping has been described as a suevitic breccia with an origin at least in part as fallback material recent mapping and a redefined stratigraphy have emphasized similarities and differences in its various vitric phases both as clast types and discrete intrusive bodies the nature of the onaping and that of other suevitic breccias overlying impact melt sheets is reviewed the relative thickness internal stratigraphic and lithological character and the relative chronology of depositional units indicate multiple processes were involved over some time in the formation of the onaping the sudbury structure formed in a foreland basin and water played an essential role in the evolution of the onaping as indicated by a major hydrothermal system generated during its formation taken together observations and interpretations of the onaping suggest a working hypothesis for the origin of the onaping that includes not only impact but also the interaction of sea water with the impact melt resulting in repeated explosive interactions involving proto sic materials and mixing with pre existing lithologies this is complicated by additional brecciation events due to the intrusion of proto sic materials into the evolving and thickening onaping fragmentation mechanisms changed as the system evolved and involved vesiculation in the formation of the upper two thirds of the onaping

on remote sensing of vertical shear of ocean surface currents by means of a single frequency vhf radar we propose and test experimentally a new way of probing vertical shear of ocean surface currents by means of a single frequency vhf radar the key idea is to use additional information provided by the so called secondary peaks in radar echo spectra which appear due to nonlinearity results of the field experiment carried out in the rhone s delta show that the new method does enable one to probe the vertical shear with a reasonable accuracy and has potential for further development

buoy measurements of wind wave relations during hurricane matthew in 2016 abstractstudies suggested that neutral stability wind speed at 10 m u10 9 m s 1 and wave steepness hs lp 0 020 can be taken as criteria for aerodynamically rough ocean surface and the onset of

major and trace element constraints on the petrogenesis of a fault related pseudotachylyte western blue ridge province north carolina a newly identified 6 cm thick zoned pseudotachylyte from the western blue ridge province of north carolina is interpreted to be the result of episodic melting on a reactivated brittle fault previously active in the ductile regime kinematic indicators in cataclasites associated with the pseudotachylyte indicate top to the northeast shear whereas kinematic indicators in mylonites indicate top to the northwest shear higher concentrations in the pseudotachylyte of al2o3 k2o feo and depletion in sio2 are explained by the total fusion of micas and partial fusion of k feldspar 60 leaving quartz and refractory phases as residual enrichment of the pseudotachylytes in ba2 rb sr2 and eu2 provide additional evidence for the preferential melting of k feldspar the trace element signature of the pseudotachylytes similar ree patterns ba k k rb ba rb zr hf ti cr ratios and entrained lithoclasts identify the source of the melt as cataclastically deformed mylonite of the hangingwall the similarity of the ree patterns in the pseudotachylytes and the source rock is explained by the entrainment and or dissolution of ree bearing phases in the melt in proportion to its volume these data indicate that coseismic flash melting is distinctly different from equilibrium partial melting and that trace elements can be used to identify the source rock and distinguish those phases that melt from those that remain residual

rare earth element speciation in geothermal fluids from yellowstone national park wyoming usa abstract elevated concentrations 20 1133 nmol kg of rare earth elements ree are present in acid sulphate and acid sulphate chloride hydrothermal waters of the yellowstone national park ynp we used recently estimated thermodynamic data haas et al 1995 to speciate seventeen ynp hydrothermal fluids with the eq3nr code the fluids show a range in ph 2 0 4 0 and temperature 70 93 c and are of varied chemistry with tds 155 2 075 ppm sulphate 100 10 325 mol kg chloride 190 24 580 mol kg fluoride 26 1 790 mol kg and so 4 f 0 8 323 field temperature and ph measurements were used in the modelling and saturation with kaolinite and quartz was assumed although quartz was actually supersaturated where possible oxygen fugacity was calculated from the analytical sulphate sulphide ratios otherwise it was set above the hematite magnetite buffer and pyrite saturation although speciation calculations show that this is not critical carbonate and phosphate levels were set at the analytical detection limit with the exception of 4 waters for which analytical data for phosphate existed the waters show little fractionation of ree relative to their host rhyolitic volcanics it appears that the ree abundances of hydrothermal fluids resulting from alteration of ynp rhyolites are unaffected by the presence of potential complexing species i e that acid alteration completely strips ree from the portion of the rocks that it affects without any fractionation across the ree series the main control over ree speciation is the relative abundances of potential complexing agents however ph and absolute abundances are also important in the most acidic waters ph 2 0 the free ion is the major species when salinity and so 4 cl are low 60 80 of each ree and ree complexes with chloride can be significant up to 5 for higher so 4 cl values sulphate complexes dominate 80 90 for less acid waters ph 2 8 4 0 fluoride is the main complexing agent in low so 4 f fluids but as the so 4 f ratio increases the sulphate species become dominant especially for the light ree lree

ocean surface wave spectra inside tropical cyclones abstractdirectional wave spectra acquired in hurricane reconnaissance missions are compared with wind wave spectral models the comparison result is quantified with two indices of model measurement spectral agreement in the main region of hurricane coverage the indices vary sinusoidally with the azimuth angle referenced to the hurricane heading while showing a weak dependence on the radial distance from the hurricane center the measured spectra agree well with three models evaluated in the back and right quarters and they are underdeveloped in the front and left quarters the local wind and wave directions also show a weak radial dependence and sinusoidal variation along the azimuth the wind and wave vectors are almost collinear in the back and right quarters they diverge azimuthally and become almost perpendicular in the left quarter the azimuthally cyclical correlation between the indices of spectral agreement and the wind wave directional difference is well described by the sinusoidal variations

the growth rate of finite depth wind generated waves abstract fetch limited wind wave experiments traditionally investigate the growth of wave energy with distance from shore donelan m skafel m graber h liu p schwab d venkatesh s 1992 on the growth rate of wind generated waves atmos ocean 30 457 478 have however shown that for deep water conditions it is advantageous to investigate the differential growth between points located along the fetch based on the extensive data set collected by young i r verhagen l a 1996a the growth of fetch limited waves in water of finite depth part i total energy and peak frequency coastal eng 28 47 78 this approach has been extended to finite depth conditions the data clearly show that at short fetches the growth rate is comparable to deep water conditions at longer fetches the finite depth influences increase and the growth rate decreases compared to deep water finally the waves approach a depth limited state where the growth rate becomes zero based on the observed differential growth between measurement stations a relationship is developed which can be integrated to yield the development of the total energy with fetch this relationship is significantly more flexible than previous finite depth growth relationships cases in which the water depth and or wind speed vary with fetch can be investigated in particular it is shown that the development of the atmospheric boundary layer with fetch has a significant influence on the observed wave growth by the inclusion of a realistic relationship for the boundary layer development it is shown that apparently anomalous features of the young i r verhagen l a 1996a the growth of fetch limited waves in water of finite depth part i total energy and peak frequency coastal eng 28 47 78 data set can be explained

boundary layer turbulence over surface waves in a strongly forced condition les and observation abstractthe impact of sea state on air sea momentum flux or wind stress is a poorly understood component of wind wave interactions particularly in high wind conditions the wind stress and mean

petrographic and melt inclusion constraints on the petrogenesis of a magmaclast from the venetia kimberlite cluster south africa abstract kimberlitic magmaclasts are discrete ovoid magmatic fragments that formed prior to emplacement from disrupted kimberlite magma to provide new constraints on the origin and evolution of the kimberlite melts we document the mineralogy and petrography of a magmaclast recovered from one of the ca 520 ma venetia kimberlites south africa the sample bi9883 has a sub spherical shape and consists of a 10 mm diameter central olivine macrocryst surrounded by porphyritic kimberlite the kimberlitic material consists of concentrically aligned altered olivine phenocrysts set in a crystalline groundmass of calcite chromite perovskite phlogopite apatite ilmenite titanite sulphides rutile and magnetite along with abundant alteration phases i e serpentine talc and secondary calcite these features are typical of archetypal hypabyssal kimberlites we examined primary fluid melt inclusions in chromite perovskite and apatite containing a diversity of daughter phases chromite and perovskite host polycrystalline inclusions containing abundant alkali carbonates i e enriched in k na ba sr phosphates na k chlorides sulphides and equal to lesser quantities of olivine phlogopite and pleonaste in contrast apatite hosts polycrystalline assemblages with abundant alkali carbonates and na k chlorides and lesser amounts of olivine monticellite and phlogopite numerous solid inclusions of shortite na 2 ca 2 co 3 3 na sr carbonates and apatite occur in groundmass calcite along with fluid inclusions containing daughter crystals of na carbonates and na chlorides the primary inclusions in chromite perovskite and apatite are considered to represent remnants of fluid s melt s trapped during crystallisation of the host minerals whereas the fluid inclusions in calcite are probably secondary in origin the component proportions of these primary fluid melt inclusions were estimated in an effort to constrain the composition of the evolving kimberlite melt these estimates suggest melt evolution from a silicate carbonate kimberlite melt that became increasingly enriched in carbonates phosphates alkalis and chlorides in response to the fractional crystallisation of constituent minerals i e olivine to apatite the concentric alignment of crystals around the olivine kernel and ovoid shape of the magmaclast can be ascribed to the low viscosity of the kimberlite melt and rapid rotation whilst in a liquid or partial crystalline state or to progressive layer by layer growth of the magmaclast although the mineralogy of our sample is similar to hypabyssal kimberlites worldwide it differs from hypabyssal kimberlite units in the main venetia pipes which contain monticellite phlogopite rich assemblages and segregationary matrix textures therefore magmaclast bi9883 probably originated from a batch of magma distinct from those that produced known hypabyssal units within the venetia kimberlite cluster

apatite compositions and groundmass mineralogy record divergent melt fluid evolution trajectories in coherent kimberlites caused by differing emplacement mechanisms kimberlites are pipe like igneous bodies consisting of a pyroclastic crater and diatreme commonly underlain by coherent root zone rocks and with associated dyke sill complexes the processes that control the different modes of coherent kimberlite emplacement remain uncertain in addition late evolution of kimberlite melts during emplacement into the upper crust remains poorly constrained therefore it is unclear whether there is a link between melt composition evolution and the emplacement mechanism of coherent kimberlites i e planar dykes sills vs irregular bodies in the root zone an absence of comparative studies on late stage magmatic phases across the different emplacement modes of coherent kimberlite from the same locality hamper resolution of these issues therefore we report petrographic and mineral chemical data for groundmass apatite in samples of dyke sill and root zone kimberlites from the kimberley cluster south africa early crystallised phases olivine spinel mg ilmenite in dyke sill and root zone kimberlites have indistinguishable compositions and hence crystallised from similar primitive melts conversely apatite compositions are generally distinct in dyke sill low sr high and variable si and root zone kimberlites high and variable sr low si the si enrichment of apatite in dykes sills is attributed to the coupled incorporation of co32 and sio44 for po43 reflecting higher co2 contents in their parental melts and potentially higher si contents due to the preferential crystallisation of carbonates over mica monticellite the low sr contents of apatite in dyke sill kimberlites reflect equilibrium with a kimberlite melt i e dsr is close to unity for carbonate and silicate melts whereas the higher sr contents of apatite in root zone kimberlites require crystallisation from or overprinting by a h2o co2 fluid significantly higher dsr the relative enrichment of co2 in kimberlite dykes sills is evident from the abundance of carbonates the presence of mesostasis dolomite and calcite phenocrysts in some samples and concomitant reduced proportions of other groundmass phases e g serpentine mica monticellite during late alteration of kimberlite dykes sills monticellite is typically replaced by carbonates whereas olivine and pleonaste are relatively stable indicating the melts which form dykes sills evolve to higher co2 h2o ratios it is unlikely that these two distinct evolutionary paths were caused by crustal contamination before or during near surface magma emplacement because crustal assimilation is not recorded in the o and sr isotopic composition of late crystallising olivine rinds or carbonates respectively we suggest that higher concentrations of co2 are retained in kimberlite dykes sills due to higher confining pressures i e lack of breakthrough to the surface in contrast exsolution of co2 from root zone kimberlites increased melt h2o co2 ratios and promoted the crystallisation of mica and monticellite at the expense of dolomite and calcite apatite compositions have the potential to aid in the discrimination of kimberlites from lamproites higher lree sr f and s lower si contents and carbonatites higher lree f cl and s lower fe contents however the compositions of kimberlitic apatite overlap those from aillikites probably due to similar late stage melt compositions

distribution of sea surface elevations in intermediate and shallow water depths abstract waveforms described by the second order stokes type approximations are prone to display anomalous troughs with spurious negative crests the systemic occurrence of such physically unrealistic features restricts the range of relative validity of second order models and causes serious errors in modeling the statistics of sea surface elevations especially in intermediate and shallow water depths as a case of practical importance in this regard this study focuses on and elaborates the nature of the second order finite depth narrowband model a critical review of the conventional formulation of this model reveals that its range of applicability as a statistically viable model of irregular waves is severely limited at relatively shallow water depths however a subsequent analysis allows the same model to be modified and reduced to a simpler stochastic form with an attendant first order probability structure free of anomalies from deep to shallow water depths comparisons with laboratory and field data representative of highly nonlinear waves in the shoaling and surf zones indicate that given the skewness coefficient the modified model provides predictions in general agreement with the distributions of observed surface elevations it also offers relative simplicity and a wider range of applicability than some other models previously proposed elsewhere

recrystallized impact glasses of the onaping formation and the sudbury igneous complex sudbury structure ontario canada abstract the origin of the sudbury structure and of the associated heterolithic breccias of the onaping formation and the sudbury igneous complex have been controversial while an impact origin of the structure has gained wide acceptance over the last 15 years the origin of the recrystallized onaping formation glasses and of the igneous complex is still being debated recently the interpretation of the breccias of the onaping formation as suevitic fall back impact breccias has been challenged the igneous complex is interpreted either as a differentiated impact melt sheet or as a combination of an upper impact melt represented by the granophyre and a lower impact triggered magmatic body consisting of the norite sublayer formations the onaping formation contains glasses as fluidal and nonfluidal fragments of various shapes and sizes they are recrystallized and our research indicates that they are petrographically heterogeneous and span a wide range of chemical compositions these characteristics are not known from glasses of volcanic deposits this suggests an origin by shock vitrification an interpretation consistent with their association with numerous and varied country rock clasts that exhibit microscopic shock metamorphic features the recrystallized glass fragments represent individual solid state and liquid state vitrified rocks or relatively small melt pods the basal member lies beneath the gray and black members of the onaping formation and where not metamorphic has an igneous matrix igneous textured melt bodies occur in the upper two members and above the basal member a comparison of the chemical compositions of recrystallized glasses and of the matrices of the basal member and the melt bodies with the components and the bulk composition of the igneous complex is inconclusive as to the origin of the igneous complex basal member matrix and melt bodies on average are chemically similar to the granophyre of the sudbury igneous complex suggesting that they are genetically related our chemical results allow interpretation of the entire igneous complex as a differentiated impact melt however they are also consistent with the granophyre alone being the impact melt and the norite and quartz gabbro beneath it representing an impact triggered magmatic body this interpretation is preferred as it is consistent with a number of field observations a re evaluation and extension of structural field studies and of geochemical data as well as a systematic study of the contact relationships of the various igneous phases of the igneous complex are needed to establish a sudbury impact model consistent with all data and observations

low frequency mean square slopes and dominant wave spectral properties toward tropical cyclone remote sensing spectral properties near the dominant wave region influence significantly the surface roughness relevant to ocean remote sensing employing low frequency microwave sensors the critical parameters characterizing dominant waves are wind speed and dimensionless spectral peak frequency which is the inverse wave age the dimensionless spectral peak frequency can be expressed as an equivalent dimensionless fetch or duration the connection between dominant waves and surface roughness is the spectral slope this paper presents a surface wave spectral model designed for low frequency microwave remote sensing with special emphasis on tropical cyclone tc applications the key elements of the spectral model are 1 a general spectral function with coefficients accommodating a variable spectral slope and 2 a parametric function connecting the spectral slope and wind speed which is established with the mean square slope mss observations obtained inside hurricanes by the global positioning system reflectometry technique in order to make use of the mss observations inside hurricanes parametric models of the spatial distributions of wind speed and dimensionless spectral peak frequency inside tcs are developed the parametric models are based on the wind and wave similarity relationships derived from analyses of hurricane hunter measurements

coefficients for sea surface wind stress heat flux and wind profiles as a function of wind speed and temperature surface layer coefficients for wind profiles wind stress and heat flux in typical open sea conditions are briefly reviewed businger dyer flux gradient relationships and a charnock wind stress formula fit the empirical data and are dimensionally consistent these have been solved by an iterative method and the results are presented in a tabular form suitable for climatological calculations from marine wind and temperature data

the churchill kimberlite field nunavut canada petrography mineral chemistry and geochronology seventy nine kimberlite intrusions have been identified in the churchill province nunavut the result of an aggressive diamond exploration program by shear minerals ltd and their partners this i

decomposing observations of high frequency radar derived surface currents by their forcing mechanisms locally wind driven surface currents 1 the wind impulse response function and transfer function for high frequency radar derived surface currents off southern san diego are calculated using several local wind observations the spatial map of the transfer function reflects the influence of the coast on wind current dynamics near the coast within 20 km from the shoreline the amplitudes of the transfer function at inertial and diurnal frequencies are reduced due to effects of coastline and bottom bathymetry meanwhile the amplitude of low frequency currents increases near the coast which is attributed to the local geostrophic balance between cross shore pressure gradients against the coast and currents locally wind driven surface currents are estimated from the data derived response function and their power spectrum shows a strong diurnal peak superposed on a red spectrum similar to the spectra of observed winds current magnitudes and veering angles to a quasi steady wind are typically 2 5 of the wind speed and vary 50 90 to the right of the wind respectively a wind skill map is introduced to present the fractional variance of surface currents explained by local winds as a verification tool for wind data quality and relevance moreover the transfer functions in summer and winter are presented to examine the seasonal variation in ocean surface current response to the wind associated with stratification change

measurements of the viscous tangential stress in the airflow above wind waves 1 the stress and drag at the surface of the ocean are crucial parameters for both short term forecasting and the modeling of long term global climate trends however the partition between viscous turbulent and wave stresses and in particular the effects of airflow separation are not well understood we present direct measurements of the velocity in the airflow above wind generated waves we observe intermittent separation of the viscous sublayer past the crest of the wind waves leading to dramatic along wave variability in the surface viscous tangential stress these results hold for wind speeds that would normally be considered low to moderate these viscous stress measurements in the airflow above the wavy surface and within the separated region are to the best of the authors knowledge the first of this kind

genetic and chemical relationships between berthierine chlorite and cordierite in nodules associated to granitic pegmatites of sierra albarrana iberian massif spain chlorite and berthierine occur through alteration of cordierite within enclaves of metamorphic rocks transformed by the sierra albarrana pegmatites the coexistence of both phyllosilicates allows us to study their stability relationships and to compare their chemical compositions samples showing incipient replacement of cordierite by small cryptocrystalline aggregates can be identified by x ray diffraction xrd as berthierine with small quantities of chlorite electron microprobe emp analyses give mixed compositions of berthierine and cordierite samples with extensive replacement of cordierite by aggregates show similar characteristics to those with incipient replacement but some small crystals are present the last type of sample shows complete replacement of cordierite by crystals showing optical properties of chlorite and empa compositions coherent with chlorite or berthierine their xrd pattern corresponds to chlorite and their high resolution transmission electron microscopy hrtem images only show perfect sequences of 14 a lattice fringes the cryptocrystalline aggregates of the samples with incipient and extensive replacement present coexistent areas of 14 a and 7 a lattice fringes that are intergrown at different levels 1 large areas 1 m of 7 a layers 2 packets of 7 a layers between 14 a layer areas with visible 7 a to 14 a lateral changes 3 random mixed layers 7 a 14 a chlorite is the final stable product of alteration of cordierite with berthierine as an intermediate metastable phase energy dispersive x ray spectrometry microanalyses of 14 a 7 a and 14 7 a areas show lack of systematic differences in chemical compositions between both phyllosilicates which may be considered as true polymorphs

on the vertical structure of wind driven sea currents abstract the vertical structure of wind driven sea surface currents and the role of wind wave breaking in its formation are investigated by means of both field experiments and modeling analysis of drifter measurements of surface currents in the uppermost 5 m layer at wind speeds from 3 to 15 m s 1 is the experimental starting point of this study the velocity gradients beneath the surface are found to be 2 to 5 times weaker than in the wall boundary layer surface wind drift identified via drift of an artificial slick with respect to 0 5 m depths is about 0 7 which is even less than the velocity defect over the molecular sublayer in the wall boundary layer at a smooth surface to interpret the data a semiempirical model describing the effect of wave breaking on wind driven surface currents and subsurface turbulence is proposed the model elaborates on the idea of direct injection of momentum and energy from wave breaking including microscale breaking into the water body momentum and energy tran

crystallization of groundmass spinel in kimberlite groundmass spinel grains in 46 kimberlite and related rocks have been analyzed and compared the majority of the spinel analyses are classified as high chromium chromite chr and magnesioulvo spinel magnetite mum and represent two significant stages of spinel growth there are also a significant number of spinel grains that are classified as xenocryst spinel xen pleonaste spinel ple and magnetite mag eight different spinel zoning trends are identified the majority of the chr spinel grains are interpreted as a primary phase that crystallized as small octahedra from kimberlite magma on the journey from the upper mantle to the final resting place in the upper crust three zoning trends lead directly away from primary chromite the major zoning trend trend 1 is from chromite to magnesio ulvo spinel magnetite this zoning trend is unique to spinel in kimberlite carbonatites and lamprophyres we suggest that this somewhat oxidizing and more magnesian trend was influenced by the high carbonate content of group i kimberlites and the rapid crystallization of the minerals during the evolution of volatiles the zoningtrend 2 involves increasing titanium and ferric iron as a function of increasing fe 2 fe 2 mg this trend is similar to the zoning of spinel in basalt and is thought to be due to co crystallization of magnesium and aluminum rich silicate minerals such as olivine and phlogopite in kimberlites or pyroxene and plagioclase in basalt zoning trend 3 in kimberlite leads away from primary chromite and towards an aluminous pleonaste ple spinel this trend is characterized by a large decease of cr cr al parallel to so called olivine spinel iso potential lines similar trends of lesser magnitude and cyclic al cr zoning have been identified in basaltic spinel this trend is thought to be due to very rapid crystallization under conditions of supersaturation where the crystallization of spinel affects the local environment ahead of the growing spinel crystal i e diffusion controlled crystallization the tendency for immiscibility between ferrite or titanate rich spinel and aluminate rich spinel pleonaste has a great influence on trends 1 and 3 zoning and also on atoll spinel formation very local conditions such as nucleation or lack of nucleation of other minerals can influence both the textural environment and composition of kimberlitic spinel