spatial distribution of intrinsic and scattering seismic attenuation in active volcanic islands ii deception island images this work has been partially supported by the spanish project ephestos cgl2011 29499 c02 01 by the eu project ec fp7 mediterranean supersite volcanoes med suv by the basque government researcher training program bfi09 277 and by the regional project grupo de investigaci on en geof isica y sismolog ia de la junta de andaluc ia rnm104 edoardo del pezzo was partly supported by dpc ingv projects unrest speed and v2 precursori

array analysis of seismograms from explosive sources evidence for surface waves scattered at the main topographical features in this article we analyze the seismic wavefield produced by blasts fired at mt vesuvius for a deep seismic sounding experiment and recorded by a dense short period three component seismic array seismograms from five explosions occurring at the bottom of wells located at different distances and azimuth with respect to the array site have been analyzed with the zero lag cross correlation technique applied to both vertical and horizontal components in the frequency range 3 7 hz the aim is to analyze the portion of the seismograms long after the first p onset in order to obtain the slowness and backazimuth distribution of correlated secondary phases polarization analysis in time domain carried out using the array covariance matrix technique has also been applied to the well correlated phases to determine their wave composition results show that the correlated phases detected in the coda of the seismogram shots are composed almost entirely of surface waves location of the scatterers shows a high concentration of the scatterers in and around the volcanic edifice of mt vesuvius confirming that topographical irregularities play an important role in the generation of the high frequency scattering phenomena

time resolved seismic tomography detects magma intrusions at mount etna the continuous volcanic and seismic activity at mount etna makes this volcano an important laboratory for seismological and geophysical studies we used repeated three dimensional tomography to detect variations in elastic parameters during different volcanic cycles before and during the october 2002 january 2003 flank eruption well defined anomalous low p to s wave velocity ratio volumes were revealed absent during the pre eruptive period the anomalies trace the intrusion of volatile rich 4 weight percent basaltic magma most of which rose up only a few months before the onset of eruption the observed time changes of velocity anomalies suggest that four dimensional tomography provides a basis for more efficient volcano monitoring and short and midterm eruption forecasting of explosive activity

seismic scattering and absorption mapping from intermediate depth earthquakes reveals complex tectonic interactions acting in the vrancea region and surroundings romania abstract the vrancea region located at the southeastern edge of the carpathians arc bend is a region of intense seismicity whose major earthquakes produce hazard in southeastern europe despite the consequent focus of the geophysical and geological community on providing accurate structural and dynamical models of vrancea these are still subject to numerous controversies and debates in the present study we use intermediate depth seismicity recorded by the broadband stations of the romanian seismic network between 2009 and 2011 to measure s wave peak delay times and late time coda quality factors after mapping these two quantities in space a cluster analysis provides a quantitative structural interpretation of the region in terms of different attenuation mechanisms affecting the seismic wave field i e seismic scattering and seismic absorption the results show that scattering is higher west and northwest of vrancea while absorption dominates in the focsani basin located in the forearc region in general we obtain higher absorption in stable regions with patterns emphasized at high frequency affected by the presence of hydrocarbons and natural gas reservoirs in the upper crustal layers regions characterized by active seismicity and structural heterogeneity show higher scattering spatially correlated with the highest velocity contrasts and the lowest density the high frequency scattering absorption contrasts obtained using the cluster analysis depict a southwest to northeast lithospheric contrast following the epicentral trend of vrancea earthquakes and characteristic of either lithospheric subduction or delamination low frequency cluster analysis results sampling deeper earth layers mark a unique high absorption trend perpendicular to the epicentral trend feasibly linked to neogene volcanism and induced by the back arc mantle upwelling its most recent expression is ciomadul volcano located at the northwestern limit of the absorption trend

middle eocene seagrass facies from apennine carbonate platforms italy abstract two stratigraphic sections located in the latium abruzzi monte porchio central apennines central italy and in the apulian carbonate platform s cesarea torre tiggiano salento southern italy were measured and sampled to document the sedimentological characteristic and the faunistic assemblages of middle eocene seagrass deposits the faunistic assemblages are dominated by porcellaneous foraminifera orbitolites alveolina idalina spiroloculina quinqueloculina triloculina and abundant hooked shaped gypsinids associated with hooked red algae and green algae halimeda fabiania rotaliids and textulariids as well as nummulitids are subordinated the samples were assigned to lutetian sbz13 16 according to the occurrence of nummulites cf lehneri alveolina ex gr elliptica idalina berthelini orbitolites complanatus slovenites decastroi and medocia blayensis at santa cesarea reticulate nummulites occur in association with alveolina spp and halkyardia minima marking the lower bartonian sbz17 three main facies associations have been recognised i larger porcellaneous foraminiferal grainstones with orbitolitids and alveolinids deposited into high energy shallow water settings influenced by wave processes that reworked the sediments associated with a seagrass ii grainstone to packstone with small porcellaneous foraminifera and abundant permanently attached gypsinids deposited in a more protected e g small embayment in situ vegetated environment iii bioclastic packstone with parautochthonous material reworked from the seagrass by rip currents and accumulated into rip channels in a slightly deeper environment the biotic assemblages suggest that the depositional environment is consistent with tropical to subtropical vegetated environments within oligotrophic conditions

alteration of uraninite from the nopal i deposit pen a blanca district chihuahua mexico compared to degradation of spent nuclear fuel in the proposed u s high level nuclear waste repository at yucca mountain nevada abstract at the nopal i uranium deposit primary uraninite nominally uo 2 x has altered almost completely to a suite of secondary uranyl minerals the deposit is located in a basin and range horst composed of welded silicic tuff uranium mineralization presently occurs in a chemically oxidizing and hydrologically unsaturated zone of the structural block these characteristics are similar to those of the proposed u s high level nuclear waste hlw repository at yucca mountain nevada petrographic analyses indicate that residual nopal i uraninite is fine grained 5 10 m and has a low trace element content average about 3 wt these characteristics compare well with spent nuclear fuel the oxidation and formation of secondary minerals from the uraninite have occurred in an environment dominated by components common in host rocks of the nopal i system e g si ca k na and h 2 o and also common to yucca mountain in contrast secondary phases in most other uranium deposits form from elements largely absent from spent fuel and from the yucca mountain environment e g pb p and v the oxidation of nopal i uraninite and the sequence of alteration products their intergrowths and morphologies are remarkably similar to those observed in reported corrosion experiments using spent fuel and unirradiated uo 2 under conditions intended to approximate those anticipated for the proposed yucca mountain repository the end products of these reported laboratory experiments and the natural alteration of nopal i uraninite are dominated by uranophane nominally ca uo 2 2 si 2 o 7 6h 2 o with lesser amounts of soddyite nominally uo 2 2 sio 4 2h 2 o and other uranyl minerals these similarities in reaction product occurrence developed despite the differences in time and physical chemical environment between yucca mountain approximate laboratory experiments and yucca mountain approximate uraninite alteration at nopal i suggesting that the results may reasonably represent phases likely to form during long term alteration of spent fuel in a yucca mountain repository from this analogy it may be concluded that the likely compositional ranges of dominant spent fuel alteration phases in the yucca mountain environment may be relatively limited and may be insensitive to small variations in system conditions

spatial distribution of intrinsic and scattering seismic attenuation in active volcanic islands i model and the case of tenerife island this work has been partially supported by the spanish project ephestos cgl2011 29499 c02 01 by the eu project ec fp7 mediterranean supersite volcanoes med suv by the basque government researcher training program bfi09 277 and by the regional project grupo de investigaci on en geof isica y sismolog ia de la junta de andaluc ia rnm104 edp has been partly supported by dpc ingv projects unrest speed and v2 precursori

radionuclide migration around uranium ore bodies in the alligator rivers region of the northern territory of australia analogue of radioactive waste repositories a review a number of u ore bodies in the northern territory of australia have been evaluated as geochemical analogues of high level radioactive waste repositories a mathematical model of the redistribution of u within the upper sequences of the ore body has been developed to rationalise observed u series fractionation in terms of differential leaching rates the rate of advance of the weathering front and assumed boundary conditions evidence is presented that the maximum uranium retardation factor down gradient of the ranger deposit is 1250 groundwater colloids were found to carry between 0 01 and 2 238u and between 0 3 and 39 230th in associated investigations of the weathered ore it was found that between 50 and 98 238u and between 74 and 97 230th is associated with the fe minerals predominantly ferrihydrite and goethite substantial 234u238u and 230th234u fractionation attributed to recoil is observed the possibility of incorporating chosen transuranic elements and fission products into the analogue is discussed

tomographic inversion of p wave velocity and q structures beneath the kirishima volcanic complex southern japan based on finite difference calculations of complex traveltimes summary we estimate the p wave velocity and attenuation structures beneath the kirishima volcanic complex southern japan by inverting the complex traveltimes arrival times and pulse widths of waveform data obtained during an active seismic experiment conducted in 1994 in this experiment six 200 250 kg shots were recorded at 163 temporary seismic stations deployed on the volcanic complex we use first arrival times for the shots which were hand measured interactively the waveform data are fourier transformed into the frequency domain and analysed using a new method based on autoregressive modelling of complex decaying oscillations in the frequency domain to determine pulse widths for the first arrival phases a non linear inversion method is used to invert 893 first arrival times and 325 pulse widths to estimate the velocity and attenuation structures of the volcanic complex wavefronts for the inversion are calculated with a finite difference method based on the eikonal equation which is well suited to estimating the complex traveltimes for the structures of the kirishima volcano complex where large structural heterogeneities are expected the attenuation structure is derived using ray paths derived from the velocity structure we obtain 3 d velocity and attenuation structures down to 1 5 and 0 5 km below sea level respectively high velocity pipe like structures with correspondingly low attenuation are found under the summit craters these pipe like structures are interpreted as remnant conduits of solidified magma no evidence of a shallow magma chamber is visible in the tomographic images

slowness anomalies from two dense seismic arrays at deception island volcano antarctica in this article we analyze the data collected by two short period seismic arrays deployed at deception volcano southern shetland islands antarctica the field survey was conducted during the 1998 1999 austral summer and was aimed at a quantitative assessment of the complex wave fields associated with the magmatic and hydrothermal activity of the volcano the two arrays had apertures of 320 m and 240 m and were separated by a distance of about 3 km during the experiment the arrays recorded several regional earthquakes related to the dynamics of the brans field strait and adjoining areas and local volcano tectonic earthquakes seismograms of earthquakes recorded at regional distances reveal a marked difference in the ap parent velocities measured at the two array sites we investigate the causes and implications of these anomalies by first comparing the effectiveness of estimating the horizontal slowness vector using three different techniques the multiple signal classification music approach the zero lag cross correlation zlc method and plane wave fitting to p wave arrival times while each technique provides the same horizontal slowness vector as the most likely estimates the plane wave fitting is associated with the most robust definition of measurement uncertainties we then investigate the dispersive properties of rayleigh waves in the 1 8 hz frequency band at both arrays and invert the two dispersion curves for a shallow velocity structure the results indicate a marked difference in the seismic velocities for the shallower 200 m beneath the two sites this may be reconciled with the observed wave vector anomalies by assuming the existence of a sharp lateral velocity heterogeneity the effect of which would be to bend downward rays impinging at the northernmost array the reliability of this hypothesis is verified by computing finite difference wave fronts in a 2d heterogeneous medium based on the morpho structural char acteristics of the volcano the inferred velocity discontinuity maybe associated with the ring fracture system bordering the collapsed caldera structure that extends over the inner part of the island

shallow structure of deception island antarctica from correlations of ambient seismic noise on a set of dense seismic arrays summary we investigated the shallow velocity structure of deception island volcano antarctica using correlations of ambient seismic noise we selected long records of noise obtained by eight seismic arrays deployed along the inner coast of deception during the period 2003 2005 using these data we calculated average dispersion curves and estimated local 1 d velocity models for the array sites the combination of these profiles allowed us to obtain a comprehensive model of the shallow velocity structure of the island the volcano is composed of relatively soft layers of pyroclastic deposits and sediments extending to a depth of about 400 m with different degrees of compaction two layers with thicknesses of about 100 and 300 m and s wave velocities of around 0 2 0 8 and 0 7 1 1 km s 1 respectively can be differentiated the deeper structure is highly variable in terms of wave velocities and layer depths although the resolving capabilities are reduced for these layers the larger s wave velocities in the range 1 3 2 8 km s 1 indicate that they can be associated with pre caldera structures and products there are substantial differences between the different models which can be spatially related to heterogeneities in the volcano structure the lowest s wave velocities may be related to the alterations produced by hydrothermal activity near the surface on the contrary the largest velocities occur near the caldera border revealing the presence of compact materials at shallow depths sharp lateral variations can also be observed in the northwest of the bay which points to the presence of nw se faults and or strong velocity gradients

intrinsic and scattering attenuation images of usu volcano japan we present intrinsic and scattering q attenuation images for usu volcano japan by analyzing over 1800 vertical seismograms by fitting the observed envelopes to the diffusion model we obtained intrinsic and scattering attenuation values at three different frequency bands using a back projection method and assuming a gaussian type weighting function we obtained the 2d images of intrinsic and scattering attenuation resolution tests confirm the robustness and reliability of the obtained images we found that scattering attenuation is the dominant process of energy loss in the frequency range analyzed which suggests strong spatial heterogeneity the resultant scattering attenuation images show an increase of attenuation toward the southwest from toya caldera which may correspond to deepening of the basement we also identify an area of low intrinsic and scattering attenuation at the summit of usu volcano which could be associated with old magma intrusions our results demonstrate a strong spatial relation between structural heterogeneities and attenuation processes in volcanic areas and confirm the efficiency of the method which can be used together with conventional imaging techniques

analysis of multiple scattering at vesuvius volcano italy using data of the tomoves active seismic experiment data from the tomoves active seismic experiment are used to study scattering effects in the shallow heterogeneous structure of vesuvius volcano seismograms from shots located on the volcano itself are characterised by spindle like envelopes small or missing p onsets missing s onsets and long codas seismograms from shots in the surroundings of the volcano on the contrary show clear and impulsive p and s onsets and short codas the different shapes of the envelopes can be explained by strong multiple scattering in the shallow heterogeneous eruptive material of the volcano and single scattering in the surrounding crust the seismograms of shots located on the volcano are modeled using the diffusion model with a diffusivity of d 0 1 km2 s for the frequency range of 2 16 hz assuming the dominance of s waves in the coda and a typical s wave velocity of around 1 5 km s this corresponds to a transport mean free path ltr of only 200 m which is 3 orders of magnitude smaller than for normal earth crust these results show that multiple scattering is an important effect which cannot be neglected in the modeling of seismic wave propagation in volcanic environments

tomographic inversion for three dimensional velocity structure at mount st helens using earthquake data tomographic inversion is applied to 17 659 p phase observations at 21 stations from 2023 earthquakes in the vicinity of mount st helens to study the three dimensional velocity structure block size for the inversion is 2 km horizontally and 2 km or more vertically locations of hypocenters are assumed known and are based on a reference one dimensional layered velocity structure a conjugate gradient technique lsqr is used to invert the large sparse system of equations augmented by regularization with a laplacian roughening matrix resolution is estimated by computing the impulse response of the inversion for various critical locations and uncertainties of the estimates are determined by a jackknife approach the results of the inversion show a remarkable correlation with known geological and geophysical features the spirit lake and spud mt plutons are characterized by high velocity regions extending to approximately 9 km depth the st helens seismic zone a band of diffuse seismicity extending nnw from the volcano is evident as a prominent low velocity lineation the change in character of the velocity anomalies south of st helens corresponds well with the near cessation of seismic activity there a low velocity anomaly beneath the crater from 6 to 16 km depths may represent modern magma accumulations

separation of scattering and intrinsic attenuation at asama volcano japan evidence of high volcanic structural contrasts abstract in this study we show 2d intrinsic and scattering q images of asama volcano obtained by analyzing 2320 waveforms from active data observed energy envelopes were fitted to the diffusion model and separate intrinsic and scattering q images were produced using a back projection method based on a gaussian type weighting function synthetic tests indicate robustness and reliability of the results areas of high scattering attenuation coincide with the volcanic edifice and the summit at which recent eruptions took place the intrinsic dissipation pattern shows a strong contrast between the east and west side of the volcanic structure with the low values observed in the west interpreted as solidified magma bodies our results demonstrate a strong relationship between structural heterogeneities and attenuation processes in volcanic areas and confirm the effectiveness of the present technique which can be used as an imaging tool complementary to conventional techniques

evidence for hydrothermal venting and sediment volcanism discharged after recent short lived volcanic eruptions at deception island bransfield strait antarctica abstract the results of a combined geophysical and geochemical research programme on deception island an active volcano at 62 43 s 60 57 w in bransfield strait antarctica are presented ultrahigh resolution acoustic data obtained with a topas topographic parameter sonar system and multibeam bathymetry simrad em1000 allow a detailed analysis of submarine vents in port foster the submerged caldera of deception island the data show three different types of seafloor structures low relief mounds high relief mounds wasp nest like and spire like structures we interpret these structures as products of sediment volcanism and seeps caused by heating and boiling of pore fluids in gas charged sediments and related to recent short lived volcanic events possibly those that occurred in 1967 1969 and 1970 in addition subsurface vertical disturbed zones formed by increased amplitude and phase inverse reflectors beneath the mounds suggest the presence of fluidised and brecciated sediments within hydrofracture systems a key finding of this study is that there appears to be a close relationship between the submarine mounds detected by our ultrahigh resolution seismic study geochemical haloes fault pathways and present day thermal anomalies in surface waters we suggest that seafloor hydrofracture systems and subsurface pipes can be re used as fluid migration pathways resulting in hydrothermal seeps and vents on the seafloor possibly up to decades after coeval volcanic eruptions

organic geochemistry and paleoenvironment of the early eocene pesciara di bolca konservat lagerstatte italy abstract exceptional preservation of fossils in so called konservat lagerstatten requires specific depositional regimes excluding disturbance of bottom sediments by either wave actions and currents or by benthic fauna we here describe a depositional model for the eocene pesciara di bolca konservat lagerstatte based on sedimentological paleoecological and detailed organic geochemical results sediments were deposited in a lagoonal like basin with stagnant bottom waters located on an extended carbonate platform that was sheltered from open marine waters by a submarine threshold run off from nearby land areas provided nutrients to support an algal community dominated by diatoms no fossil diatom shells have been identified but evidence for their presence is given by the high abundance of highly branched isoprenoids in extractable bitumens influx of terrigenous organic matter into the lagoon occurred in particular during deposition of the basal fish bearing level l1 here not only plant macrofossils amber spores and pollen but also the lipid composition indicated notable input of land plants via the presence of n c 24 to n c 32 carboxylic acids long chain n alkanes n c 27 n c 29 n c 31 and angiosperm wax triterpenoids the redox regime in general was strongly reducing as evidenced by the high concentration of sulfur vs organic carbon excellent kerogen preservation as shown by high hydrogen indices and low pristane phytane but high phytane n c 18 ratios the water column was highly stratified with anoxic saline bottom and fresh surface waters euxinic conditions with free reduced sulfur present in the photic zone could only be detected in sediments from the l1 horizon via traces of aromatic carotenoids derived from green sulfur bacteria chlorobiaceae which utilize h 2 s in anoxygenic photosynthesis the depositional regime is thus comparable to the lithographic limestones of solnhofen but based on biomarker evidence lacks the high salinities postulated for the latter biomarker composition indicates that best preservation conditions prevailed in the basal part of the studied section 0 7 m above datum but declined upon deposition of the upper part we interpret the body of the pesciara as a parasequence of the 4th order 0 01 0 5 ma with the lower part representing a relative sea level lowstand and the upper part a relative sea level highstand

crustal structure of deception island volcano from p wave seismic tomography tectonic and volcanic implications 1 deception island 62 59 s 60 41 w is an active volcano located in the bransfield strait between the antarctic peninsula and the south shetland islands the island is composed of rocks that date from 0 75 ma to historical eruptions 1842 1967 1969 and 1970 and nowadays most of its activity is represented by vigorous hydrothermal circulation slight resurgence of the inner bay floor and intense seismicity with frequent volcano tectonic and long period events in january 2005 an extensive seismic survey took place in and around the island to collect high quality data for a high resolution p wave velocity tomography study a total of 95 land and 14 ocean bottom seismometers were deployed and more than 6600 air gun shots were fired as a result of this experiment more than 70 000 travel time data were used to obtain the velocity model which resolves strong p wave velocity contrasts down to 5 km depth the joint interpretation of the vp distribution together with the results of geological geochemical and other geophysical magnetic and gravimetric measurements allows us to map and interpret several volcanic features of the island and surroundings the most striking feature is the low p wave velocity beneath the caldera floor which represents the seismic image of an extensive region of magma beneath a sediment filled basin another low velocity zone to the east of deception island corresponds to seafloor sedimentary deposits while high velocities to the northwest are interpreted as the crystalline basement of the south shetland islands platform in general in the tomographic image we observe ne sw and nw se distributions of velocity contrasts that are compatible with the regional tectonic directions and suggest that the volcanic evolution of deception island is strongly conditioned by the bransfield basin geodynamics

attenuation and source parameters at deception island south shetland islands antarctica deception island is the most active volcano of the south shetland islands antarctic peninsula group experiencing eruptions in 1967 1969 and 1970 local attenuation derived from coda analysis and source parameters derived from brune s model for well located seismic events have been studied in order to complement the available geophysical information results show abnormally lowq0 values and an abnormally high frequency dependence as well as large dispersion these factors are strongly dependent on the path travelled by the seismic wave retrieved values of the source parameters stress drop seismic moment and source radius are again abnormally low compared to world wide average values for example those obtained for the oroville california aftershock series between june and september 1976 these results are consistent with some aspects of the geology of deception island such as the very high degree of fracturing and faulting and the existence of a strong hydrothermal alteration affecting most of the subaerial volcanic rocks moreover the pattern defined for the lateral variations ofq0 shows minimum values in the inner bay of the island close to the most recent eruption vents a large reduction in spectral amplitudes over a particular frequency range occurs in several observations corresponding to the path crossing the zone of highest attenuation this observation suggests the existence of a hot magmatic intrusion produced during the most recent eruption and coincides with the superficial low density mass distribution obtained from the gravimetric model and the long wave magnetic field component obtained from magnetic surveys the width of this intrusion is estimated to be about 200 m in agreement with the previous results obtained analyzing residuals of the location of seismic events

three dimensional kernel based coda attenuation imaging of caldera structures controlling the 1982 84 campi flegrei unrest abstract coda wave attenuation imaging has risen as a state of the art technique to depict volcanic structures using their dispersion effects the 1982 84 seismic and deformation unrest at campi flegrei caldera italy is a unique example of non eruptive volcanic activity in a structured caldera here we propose the first application of 3d coda attenuation kernels to image caldera structures at multiple frequencies during unrest using sensitivity kernels is necessary to assess the effective resolution of coda imaging in highly heterogeneous volcanoes the technique relies on the solution of paasschens equations in the framework of radiative transfer theory the results map coda attenuation in the 3d space without need of pre existent velocity models the resolution and stability of the inversion solutions were examined by changing the damping parameters and outputting the corresponding images inverting for different node spacings and performing checkerboard tests these tests show that the resolution of the multiple scattering model is much lower than that provided by a standard isotropic scattering and or single scattering technique the best resolution in our model is obtained between depths of 1 km and 3 km in the centre of the model between pozzuoli town and solfatara crater the results are discussed at a frequency of 3 hz due to both longer coda durations and broader kernel illumination in this frequency range coda based 3d imaging had so far failed to provide stable results the interpretation is performed based on the extensive geological and geophysical knowledge of the caldera high attenuation anomalies below solfatara and monte nuovo mark areas either saturated with water or enriched in molten rocks feeding the respective fumarole fields the flattening and horizontal elongation of these anomalies below 2 km depth is a manifestation of the blocking and spreading around of the rising hot magmatic fluids below a previously inferred high velocity low attenuation and highly deforming caprock this caprock is not uniform likely due to the remnants of erupted structure a sw to ne trending low attenuation and high velocity anomaly deeps down to 3 km under pozzuoli we infer that the high seismicity in the region is a consequence of the stress sustained by the caprock from a 4 km deep deformation source in 1983 84 on top of this source high coda attenuation corresponds to high vp vs ratios and high direct wave attenuation the region s characteristics are likely due to the accumulation of magmatic fluids above a magmatic sill

a new fossil lagerstatte from the lower eocene of lessini mountains northern italy a multidisciplinary approach hemipelagic dark limestones within calciturbiditic deposits at monte solane in the western lessini mountains of northern italy yield a fish fauna dominated by stomiiforms a minor component of the fossil assemblage is represented by a macroalgal non calcareous flora associated with rarer terrestrial components including few angiosperm leaves and seeds micropaleontological foraminifera dinoflagellate cysts sedimentological and geochemical proxies tex86 indicate a deposition of the fossil bearing bed in a hypoxic to possibly anoxic warm restricted basin high precision dating based on rich foraminiferal and calcareous nannoplankton content allows ascribing the site to the upper part of the ypresian lower eocene the site is slightly older than the ypresian worldwide famous shallow water bolca konservat lagerstatte located in the same region convergent paleoenvironmental clues based on both microfossils and ichthyofauna indicate that the sediments were deposited in the upper bathyal zone probably between 300 and 600 m solane is therefore one of the rare and precious eocene lagerstatte to have fossilized in a deep marine setting the site contains the oldest cenozoic record of an ichthyofauna dominated by meso bathypelagic taxa

seismovolcanic signals at deception island volcano antarctica wave field analysis and source modeling the seismovolcanic signals associated with the volcanic activity of deception island antarctica recorded during three antarctic summers 1994 1995 1995 1996 and 1996 1997 are analyzed using a dense small aperture 500 m seismic array the visual and spectral classification of the seismic events shows the existence of long period and hybrid isolated seismic events and of low frequency quasi monochromatic and spasmodic continuous tremors all spectra have the highest amplitudes in the frequency band between 1 and 4 hz while hybrids and spasmodic tremors have also significant amplitudes in the high frequency band 4 10 hz the array analysis indicates that almost all the well correlated low frequency signals share similar array parameters slowness and back azimuth and have the same source area close to the array site the polarization analysis shows that phases at high frequency are mostly composed of p waves and those phases dominated by low frequencies can be interpreted as surface waves no clear shear waves are evidenced from the energy evaluation we have found that the reduced displacement values for surface and body waves are confined in a narrow interval volcano tectonic seismicity is located close to the array at a depth shallower than 1 km the wave field properties of the seismovolcanic signals allow us to assume a unique source model a shallow resonating fluid filled crack system at a depth of some hundreds of meters all of the seismic activity is interpreted as the response of a reasonably stable stationary geothermal process the differences observed in the back azimuth between low and high frequencies are a near field effect a few episodes of the degassification process in an open conduit were observed and modeled with a simple organ pipe

quantitative analysis of seismic wave propagation anomalies in azimuth and apparent slowness at deception island volcano antarctica using seismic arrays summary we analyse shot data recorded by eight seismic arrays during an active source seismic experiment carried out at deception island antarctica in 2005 january for each source we estimate the apparent slowness and propagation azimuth of the first wave arrival since both source and receiver positions are accurately known we are able to interpret the results in terms of the effect of the heterogeneities of the medium on wave propagation the results show the presence of significant propagation anomalies nearby shots produce large apparent slowness values above 0 6 s km 1 while distant shots produce small values down to about 0 15 0 20 s km 1 these values are different for each array which shows the importance of the local structure under the receiver the spatial distributions of apparent slowness are not radial as we would expect in a flat layered medium and again these distributions are different for each array the azimuth anomalies defined as the difference between the empirical estimates and the values expected in a 1 d model i e the source array directions suggest ubiquitous wave front distortions we have detected both positive and negative anomalies for some shot array geometries azimuth anomalies are quite large with values up to 60 the distribution of the anomalies depends on the position of the array some of these features can be interpreted in terms of a shallow magma chamber and shallow rigid bodies imaged by high resolution seismic tomography however several details remain unexplained further work is required including modelling of synthetic wavefields on realistic models of deception island and or apparent slowness vector tomography

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

mobility of uranium during weathering mineralogical and geochemical mechanisms of u fixation under oxidizing conditions in the vicinity of the secondary u ore deposit at koongarra australia were examined using transmission and scanning electron microscopy and thermodynamic calculations the formation of saleeite mg uo 2 2 po 4 2 1oh 2 o is the predominant mechanism for u fixation upstream from the deposit where saleeite replaces sklodowskite and granular apatite within the deposit and further downstream u is fixed in microcrystals 10 50 nm of saleeite and meta torbernite scattered within veins of fine grained 2 50 nm fe super 3 minerals primarily goethite and hematite thermodynamic calculations indicate the groundwater is undersaturated with respect to saleeite and metatorbernite and that these minerals should precipitate at higher u or p concentrations than observed this suggests that the upstream saleeite precipitated at the reaction interfaces of dissolving sklodowskite and apatite under local saturation conditions observed textural relationships of saleeite and meta torbernite microcrystals with the fe minerals combined with thermodynamic calculations suggest surface precipitation as the formation mechanism for saleeite and meta torbernite microcrystals within and downstream from the secondary ore deposit phosphorous released during the aging of ferrihydrite and u adsorbed onto fe minerals are probably the sources of the major components of the microcrystals downstream the microcrystals exist where groundwater u concentrations are as low as 10 30 mu g l once released from the ore deposit u is fixed in uranyl phosphates even where measured groundwater is undersaturated with respect to uranyl phosphates the surface precipitation is an important example of long term post adsorption u fixation in a natural system the fully crystalline and radiation damaged microstructures of saleeite indicate uranyl phosphates have formed continuously or intermittently for the last few million years

early eocene amber from the pesciara di bolca lessini mountains northern italy abstract the occurrence of amber from the world famous fossil lagerstatte of pesciara di bolca verona province is here reported for the first time this amber has been carefully analysed by means of infrared spectrophotometry ftir thermogravimetric analysis tg differential thermogravimetric analysis dtg and elemental chemical analysis then the amber from bolca has been compared with other ambers of similar age among them a sample from the cava rossi quarry monte di malo vicenza province shows striking similarities in all the physical chemical characters the fossil content of the amber levels of the pesciara and cava rossi was examined with respect to the palynomorphs and larger foraminiferans this permitted to ascertain that the two amber levels are substantially isochronous within the resolution power of the larger foraminiferan biozones according to the shallow benthic biozonation the age is in both cases sbz 11 or middle cuisian early eocene moreover the fossil assemblages allowed to reconstruct the palaeoenvironments stressing they were in both case on a shallow carbonate platform relatively close to the shoreline the pesciara palaeoenvironment was very close to the continental areas and with peculiar conditions allowing the exceptional preservation of the fishes instead the cava rossi palaeoenvironment was more distal and open to marine influxes

the p wave velocity structure of deception island antarctica from two dimensional seismic tomography abstract deception island is a volcanic island with a flooded caldera that has a complex geological setting in bransfield strait antarctica we use p wave arrivals recorded on land and seafloor seismometers from airgun shots within the caldera and around the island to invert for the p wave velocity structure along two orthogonal profiles the results show that there is a sharp increase in velocity to the north of the caldera which coincides with a regional normal fault that defines the northwestern boundary of the bransfield strait backarc basin there is a low velocity region beneath the caldera extending from the seafloor to 4 km depth with a maximum negative anomaly of 1 km s refracted arrivals are consistent with a 1 2 km thick layer of low velocity sediments and pyroclastites infilling the caldera synthetic inversions show that this layer accounts for only a small portion of the velocity anomaly implying that there is a significant region of low velocities at greater depths further synthetic inversions and melt fraction calculations are consistent with but do not require the presence of an extensive magma chamber beneath the caldera that extends downwards from 2 km depth

scattering behaviour at merapi volcano java revealed from an active seismic experiment summary the seismic structure of the stratovolcano merapi java indonesia was studied using an active seismic experiment three 3 km long seismic profiles each consisting of up to 30 three component seismometers with an interstation distance of 100 m were built up in an altitude range between 1000 and 2000 m above sea level the detailed study of the seismic properties of the propagation media in active volcanic regions is important to understand the natural seismic signals used for eruption forecasting the seismic experiment at merapi therefore concentrates on the heterogeneous structure within a radius of 5 km from the active dome where the sources of most of the natural volcanic seismic events are located the cone of merapi volcano consists of different materials changing on a small scale due to the layering of eruptive material additionally the topography of the erosion valleys leads to an irregular deposition which cannot be described by a simple 1 d layering these inhomogeneities have a strong influence on seismic signals the direct p and s waves are attenuated quickly and show only small amplitudes on seismograms the energy lost from the direct waves however is not changed into heat but scattered and can be observed as seismic coda following the direct waves the observed seismograms show a spindle like amplitude increase after the direct p phase this shape of the envelope can be explained by the diffusion model according to this model there are so many strong inhomogeneities that the direct wave can be neglected and all energy is concentrated in multiple scattered waves besides the envelope the coherence and polarization properties of the wavefield also indicate strong scattering only the first onset shows coherence over a station spacing of 100 m whereas the late phases carrying the major part of the energy are mainly incoherent the horizontal components of the seismograms have larger amplitudes than the vertical component but within the horizontal plane the polarization is almost arbitrary corresponding to waves arriving from scatterers located arbitrarily in space as a result of the inversion using the diffusion model we obtain values of the s wave scattering attenuation coefficient gs and the s wave intrinsic absorption coefficient gi in the frequency range of 4 20 hz used in this study the scattering attenuation is at least one order of magnitude larger than the intrinsic absorption gs gi the mean free path of s waves is as low as 100 m gs1 100 m the scattering coefficient is independent of frequency gsyf 0 0 whereas the coefficient of intrinsic attenuation increases with increasing frequency giyf 1 6 the natural seismic signals at merapi volcano show similar characteristics to the artificial shots the first onsets have only small amplitudes and the energy maximum arrives delayed compared to the direct waves therefore these signals appear to be strongly affected by multiple scattering also

a three dimensional qp imaging of the shallowest subsurface of campi flegrei offshore caldera southern italy to improve the knowledge of the shallowest subsurface of campi flegrei caldera a 3 d p wave attenuation tomography of the area was performed we analyzed about 18 000 active seismic traces which provided a dataset of 11 873 t measurements e g the differential traveltimes to quality factor ratios these were inverted through an adapted tomographic inversion procedure the 3 d tomographic images reveal an average qp about 70 interpreted as water saturated volcanic and marine sediments an arc like low qp structure at 0 5 1 km depths was interpreted as a densely fractured fluid saturated rock volume well matching the buried rim of campi flegrei caldera the spatial distribution of high and low qp bodies in the inner caldera is correlated with low vp values and may reflect either the differences in the percentage of fluid saturation of sediments or the presence of vapor state fluids beneath fumaroles manifestations

the bolca lagerstatten shallow marine life in the eocene the eocene limestones around the italian village of bolca occur in a series of distinct localities providing a unique snapshot of marine life in the early cenozoic famous for its fishes the localities of bolca also yield diverse invertebrate faunas and a rich but relatively understudied flora most fossils from bolca derive from the pesciara and monte postale sites which bear similar fossils but are characterized by slightly different taphonomic and environmental profiles although not precisely contemporaneous the age of these principal localities is well constrained to a narrow interval within the ypresian stage c 50 49 ma this places bolca at a critical time in the evolutionary assembly of modern marine fish diversity and of reef communities more generally

uranium transport through fractured silicic tuff and relative retention in areas with distinct fracture characteristics abstract the nopal i uranium u deposit in the pefia blanca district chihuahua mexico has been identified as analogous in some regards to the candidate u s high level waste hlw repository at yucca mountain nevada uranium transport at the nopal i deposit has been studied to investigate mechanisms by which hlw components could be transported through silicic tuff over long time periods this investigation focused on approximately 1400 m2 of essentially continuous bedrock outcrop spanning the nopal i deposit and surrounding host tuff data collected document i the distributions of u within and around the nopal i deposit ii the distribution and characteristics of the fracture network within and surrounding the deposit and iii the transport of u away from the deposit mainly along fracture paths uranium series isotopic measurements indicate mobilization of u along the margin of the deposit within the last 1 ma and significant u transport at about 54 ka transport of u away from the nopal i deposit along a few relatively continuous mesofractures achieved maximum distances at least 20 times greater than transport through the general fracture network composed of thousands of less continuous microfractures within and surrounding the deposit uranium transport away from the deposit appears to be largely independent of variations in the general fracture network pattern transport of u away from individual micro and meso fractures into homogeneous unfractured tuff matrix appears limited to distances less than 1 mm at the nopal i deposit matrix diffusion does not appear to have been an important factor for retardation of u this analysis suggests a ranking for u retention i microfracture network retention mesofracture retention and ii individual microfracture retention matrix retention

geochemical analogues of high level radioactive waste repositories abstract in this short review an attempt has been made to broaden and systematise the concept of the geochemical approach to the prediction over long time intervals of the behaviour of radionuclides leached from high level radioactive waste repositories an analogue exhibits two essential properties 1 a spatial discontinuity across which the migration of indicator elements may be measured and 2 a basis for establishing a time frame selected examples of published analogues are discussed such research is of value in assessing the siting of repositories for the following reasons 1 1 analogues may determine the limits of migration of indicator elements under conditions which are frequently more rigorous than those met under operating conditions 2 2 they can be used to establish a scientific basis for the long term prediction of radionuclide migrarion rates 3 3 the findings may be transferred from the site of the geochemical analogue to that of the waste repository 4 4 the locality of the proposed repository site may be developed as an analogue of the distant field radionuclide transport regime under operating conditions

array tracking of the volcanic tremor source at deception island antarctica we have found experimental evidence which shows that the volcanic tremor recorded at deception island south shetland islands antarctica is a superposition in time of overlapping hybrid events we studied data from a small aperture seismic array data analysis for tremor and hybrids included 1 spectral analysis 2 apparent slowness and back azimuth determination by using the zero lag cross correlation method and 3 polarization analysis both types of events share these common features a two dominant spectral bands at frequencies 1 3 hz the most energetic and 4 8 hz b several coherent phases with the same back azimuth to the source and apparent slowness along the whole signal c in the high frequency band the apparent slowness is very low around 0 17 s km indicating the propagation of body waves d in the low frequency band the apparent slowness is high around 1 6 s km consistent with the presence of surface waves and e clear p wave onset followed by a complex pattern of rayleigh waves therefore both types of events are strongly related because they share the same source region the same wave propagation properties and the same wave composition moreover several arrivals that resemble a single hybrid event have been found along the tremor signals due to these reasons we hypothesize that volcanic tremor of deception island is a superposition of hybrid type events the source of both types could be the interaction between thaw water and hot materials in a shallow aquifer

the recent seismo volcanic activity at deception island volcano abstract this paper reviews the recent seismic studies carried out at deception island south shetland islands antarctica which was monitored by the argentinean and spanish antarctic programs since 1986 several types of seismic network have been deployed temporarily during each antarctic summer these networks have consisted of a variety of instruments including radio telemetered stations autonomous digital seismic stations broadband seismometers and seismic arrays we have identified two main types of seismic signals generated by the volcano namely pure seismo volcanic signals such as volcanic tremor and long period lp events and volcano tectonic vt earthquakes their temporal distributions are far from homogeneous volcanic tremors and lp events usually occur in seismic swarms lasting from a few hours to some days the number of lp events in these swarms is highly variable from a background level of less than 30 day to a peak activity of about 100 events h the occurrence of vt earthquakes is even more irregular most vt earthquakes at deception island have been recorded during two intense seismic crises in 1992 and 1999 respectively some of these vt earthquakes were large enough to be felt by researchers working on the island analyses of both types of seismic events have allowed us to derive source locations establish seismic source models analyze seismic attenuation calculate the energy and stress drop of the seismic sources and relate the occurrence of seismicity to the volcanic activity pure seismo volcanic signals are modelled as the consequence of hydrothermal interactions between a shallow aquifer and deeper hot materials resulting in the resonance of fluid filled fractures vt earthquakes constitute the brittle response to changes in the distribution of stress in the volcanic edifice the two vt seismic series are probably related to uplift episodes due to deep injections of magma that did not reach the surface this evidence however indicates the high potential for future volcanic eruptions at deception island

facies analysis palaeoenvironmental reconstruction and biostratigraphy of the pesciara di bolca verona northern italy an early eocene fossil lagerstatte abstract the world famous pesciara di bolca fossil lagerstatte has been examined in its palaeontological and sedimentological aspects a re examination of the co occurring age diagnostic larger foraminifers alveolina and nummulites indicates a sbz 11 late ypresian age sedimentological characters allowed us to distinguish between autochthonous micritic limestones and allochthonous biocalcarenites biocalcirudites the latter are the product of penecontemporaneous transport from nearby areas the depositional model here proposed involves a basin with restricted circulation and a prevailing micrite sedimentation this basin was affected by relative sea level oscillations and coarser grained storm induced deposition the palaeoenvironmental reconstruction suggests neighbouring emerged land and very shallow sea bottoms inhabited by large foraminifers such as alveolina and nummulites as yet it is unclear whether a true coral reef was present nearby the bottom on which the pesciara deposits accumulated is interpreted as poorly oxygenated possibly with stromatolite like bacterial mats thus allowing the exceptional preservation of the fish and plants

gravimetric study of the shallow basaltic plumbing system of tenerife canary islands abstract recent studies on intraplate volcanic islands reveal that magma ascends sub vertically through these volcanic edifices following well defined zones in the lithospheric mantle and oceanic crust and occasionally suffering lateral propagation along rift zones when it reaches very shallow depths visualizing the internal structure of the shallowest part of such magma plumbing systems is crucial to understanding magma transport and the location of basaltic volcanism in these volcanic environments tenerife canary islands is a very good example of an intraplate volcanic island in which the distribution of basaltic volcanism includes well defined rift systems and wider monogenetic fields where cinder cones form clusters along different tectonic alignments in order to characterize the structure of the uppermost part of the basaltic plumbing system of tenerife we conducted a detailed gravimetric study of the north western central and southern sectors of the island we developed a 3d density contrast model of the subsoil based on the application of a genetic algorithm for the inversion of gravity data the results of our inverse modelling suggest that the observed gravimetric anomalies below the northwestern rift zone are shallow and aligned parallel to this structure this is consistent with a shallow character for the rift system and a lateral migration of magma along it that comes from a deeper zone located towards the east of this rift zone conversely the anomalies located in the south are also shallow but are distributed along more than one alignment and are connected to much deeper sub vertical similar density anomalies these results support the existence of several main channels at the north and south of the island that allow the ascent of deep basaltic magma to shallower zones of tenerife there magma may be either caught by the rifts systems being distributed laterally and occasionally erupting or may continue its ascent to the surface using a secondary system of shallow fractures that dominates the southern part of tenerife the results of our inverse model also offer new insights on others aspects of the internal structure of tenerife such as the distribution of the basaltic shield or that of las canadas caldera

controlled excavations in the pesciara and monte postale sites provide new insights about the palaeoecology and taphonomy of the fish assemblages of the eocene bolca konservat lagerstatte italy abstract the eocene konservat lagerstatte of bolca italy is famous for the abundance and exquisite preservation of its fossils although the bolca sites have provided one of the most studied ichthyofaunistic fossil assemblages of the world several aspects about the community structure and the biostratinomic processes that led to the accumulation of its fish remains have been neglected or underestimated in order to improve our knowledge concerning the palaeoecology and palaeoenvironment of bolca a quantitative palaeoecological and taphonomic analysis of the fish remains collected during controlled excavations at the pesciara and monte postale sites is presented herein the results of these analyses concur to suggest that these two sites have different speciose fish assemblages and different depositional contexts the high quality preservation of the fishes from the pesciara site has allowed for the species level identification of most of its specimens providing a good resolution of its palaeoecological spectrum the pesciara fish assemblage is defined by a sharp oligarchic structure clearly dominated by planktivorous taxa the taphonomic features confirm that the sediments were deposited in an intraplatform basin in which anoxic conditions at the bottom and the development of the biofilm acted as promoters of high quality fossil preservation on the other hand the moderate preservation quality of the fishes from monte postale does not allow for most of the specimens to be identified at the genus or species level making it difficult to interpret the ecological and trophic relationships within this assemblage nevertheless the abundance of marine and terrestrial plants coupled with the large number of invertebrates including abundant corals concur to suggest that the sediments of monte postale were likely deposited close to an emerged coastal area characterized by mangroves seagrass and coral reefs the prominent disgregation of fish skeletons coupled with the unimodal dispersion of the elements and bioturbations clearly indicate a high degree of disturbance in the monte postale palaeoenvironment suggesting at least periodic aerobic conditions at the bottom

shallow seismic attenuation and shear wave splitting in the short period range of deception island volcano antarctica abstract the occurrence of a seismic series in deception island volcano antarctica composed of hundreds of local volcano tectonic earthquakes has permitted us to study the seismic attenuation of such a volcanic environment in the short distance and high frequency range this study has been performed using p waves s waves and coda waves and applying different frequency dependent and independent techniques the methods used for this analysis have been spectral and broadening of the pulse for direct p and s waves coda normalization for s waves and single back scattering model for coda waves the results show that in general q values are significantly smaller for the entire frequency range used 6 30 hz than those found in other volcanic and tectonic areas the attenuation for p waves is greater than for s waves in the frequency independent methods with a q q p ratio that ranges between 1 9 and 3 2 comparing the q factor obtained for s waves we have observed clear differences as a function of the method used the coda normalization method has supplied significantly higher q values q d than the other two methods q we have interpreted this discrepancy as an effect of the methods coda normalization and single back scattering methods eliminate the contribution of the near surface attenuation in their q values comparing both q and q d we have estimated the near surface attenuation under the recording site named q on the other hand we have observed that q d has anomalous frequency dependence with a minimum value at 21 hz this pattern is interpreted as an effect of strong scattering of the seismic waves in the source area of the earthquakes q c values depend clearly with frequency and lapse time and the lapse time dependence could be interpreted as a depth dependence of the seismic attenuation in deception island volcano antarctica the obtained q values have allowed us to separate the contribution of intrinsic and scattering attenuation deriving that the scattering attenuation is predominant over the intrinsic effects finally in order to investigate how the heterogeneous medium of the volcanic island could produce other effects we have checked whether it produces polarization of the shear waves the preliminary results of the polarization direction indicate a main e w strain direction all these evidences reveal the strongly heterogeneous structure of deception island volcano

geomagnetic secular variation of bransfield strait western antarctica from analysis of marine crossover data summary tracking the secular variation of the geomagnetic field in the past is severely limited in some cases by factors relating to the remoteness of the sites this is maximal in the antarctic where the remote location and severe climate lead to logistic limitations that make it difficult to keep a continuous record of magnetic field variations from the magnetic information available from historical marine expeditions it is possible to infer this time varying component from the comparison of readings at crossovers this study focuses on this technique discusses the impact of the different error sources and proposes a simple mathematical procedure to infer average secular variation rates the result is validated by comparing it with local data from the arctowski and livingston magnetic observatories sited in the area additionally using a high quality data set from a local area in the neighbourhood of deception island we have detected a systematic distribution in its secular variation this dichotomy has been interpreted in terms of a volcano magnetic signal this fact and the nature of its principal mechanisms are analysed and discussed

ecology of extant nummulitids and other larger benthic foraminifera applications in palaeoenvironmental analysis abstract larger benthic foraminifera lbf are important contributors to modern and ancient tropical shallow marine sediments over the past 30 years a substantial body of literature has built up on the ecology of modern lbf especially in terms of their environmentally sensitive depth distribution reproductive strategy and morphology and the symbiotic relationship between many larger foraminifera and photosynthetic algae over the same period the extinct genus nummulites which is abundant in eocene sediments of southern europe north africa and the arabian peninsula has increasingly been studied principally because significant volumes of hydrocarbons have been discovered reservoired within nummulitic limestones offshore tunisia and libya the modern ecological studies of lbf provide a powerful tool with which to develop palaeoecological models for fossil nummulites and other symbiont bearing larger foraminifera in the rock record

absorption and scattering 2 d volcano images from numerically calculated space weighting functions acknowledgments yosuke aoki and an anonymous reviewer greatly improved the quality of the paper all calculations were made with mathematica 10tm discussions with marie calvet danilo galluzzo mario la rocca salvatore de lorenzo jessie mayor and ludovic margerin are gratefully acknowledged the authors are supported by medsuv european project and by spanish project ephestos cgl2011 29499 c02 01 and nowaves tec2015 68752 the tides eu travel cost action provided travel money to support cooperation between luca de siena and the other authors

short paper a standardized model for tethyan tertiary carbonate ramps low latitude carbonates in massive and clinoform bedded sheets termed ramps occur throughout the tertiary tethyan realm and are characterized by recurring biofacies usually including large foraminifera rhodolithic algae coralgal patch reef and gastropod dominated sequences all can be interpreted broadly within a standardized tertiary carbonate ramp model biota can be used to define precise palaeobathymetric zones which have a predictive utility in palaeoenvironmental modelling especially where data are limited the carbonate ramp model of earlier authors has been elaborated by read 1982 and ramp formation occurs mostly in passive margin and extensional tectonic settings ramps are characterized by slope gradients of less than 1 degree and once established are conservative to change much use has been made of the ramp model for palaeozoic and mesozoic lithofacies modelling in contrast published work on cenozoic ramps is limited however tethyan ramps are particularly widespread and extend tens to hundreds of kilometres along strike and occupy tens of kilometres of slope many studies have dealt with cenozoic ramp associations and sequences e g pedley 1983 reiss hottinger 1984 purser 1973 and have demonstrated the diversity of biotal and sediment detail but without ascribing them to a ramp model biota were quick to adapt to the tertiary environments left vacant after the k t boundary extinction events new genera of foraminifera mollusca bryozoa and echinoder mata rapidly replaced the extinct forms in bursts of innovative opportunism codiacean algae rhodophyta and marine angiosperms were equally adaptive colonizers of the carbonate platforms novel biofacies associations were derived from

two dimensional seismic attenuation images of stromboli island using active data in this work we present intrinsic and scattering seismic attenuation 2 d images of stromboli volcano we used 21 953 waveforms from air gun shots fired by an oceanographic vessel and recorded at 33 inland and 10 ocean bottom seismometer seismic stations coda wave envelopes of the filtered seismic traces were fitted to the energy transport equation in the diffusion approximation obtaining a couple of separate qi and qs in six frequency bands using numerically estimated sensitivity kernels for coda waves separate images of each quality factor were produced results appear stable and robust they show that scattering attenuation prevails over intrinsic attenuation the scattering pattern shows a strong concordance with the tectonic lineaments in the area while an area of high total attenuation coincides with the zone where most of the volcanic activity occurs our results provide evidence that the most important attenuation effects in volcanic areas are associated with the presence of geological heterogeneities

formation and evolution of the cigar lake uranium deposit based on u pb and k ar isotope systematics a systematic geochronological study was conducted on the cigar lake uranium deposit u pb and pb pb systematics were applied to different types of uranium ore and various associated sheet silicates were dated by the k ar method these two approaches define a widespread retrograde metamorphic event in the basement which occurred at about 1780 ma during the hudsonian orogeny and a four stage evolutionary model for the ore deposit this model is compatible with the history of other unconformity type uranium deposits in the athabasca basin the first stage in the evolution of the cigar lake uranium deposit is marked by uraninite crystallization at 1341 17 ma which in association with arsenides and sulpharsenides constitutes the mineralization of economic interest main orebody the second stage characterized by a fe kaolinite and fe illite paragenesis occurred locally at about 900 ma the third stage involved uranium mobilization at about 325 ma and is characterized by i preferential loss of radi

the three dimensional structure of kilauea volcano hawaii from travel time tomography a linear travel time tomography study of the most active shield volcano of the world kilauea volcano hawaii was undertaken to determine the lateral heterogeneities produced by its intricate magmatic and tectonic environment kilauea provides an ideal setting to do tomography because of its dense seismograph array and many local earthquakes that allow excellent ray coverage of complex subsurface features local p wave data from 12 295 events were inverted using a one dimensional layered velocity model inversions were done for two cell sizes 5 5 5 km and 1 1 1 km to resolve structural regions on different length scales this study provided a view of the average velocity variations relative to a one dimensional velocity model analysis and interpretation of the tomographic images allowed us to infer the following model the main shallow magma reservoir is delineated by a slow velocity region southeast of the summit from 0 to 2 km depth there is a distinct high velocity region centered northwest of the summit from 0 to 2 km depth that represents a cap of dense intrusive dikes surrounding the magma chamber we suggest that the shallow reservoir is a narrow compartmentalized region of sills and dikes centered just south southeast of halemaumau caldera below the main reservoir the summit is imaged as a slightly fast region from 5 to 10 km in the coarse model indicating that the main conduit is structurally defined by an intrusive dike complex until about 10 km the rift zones of kilauea are imaged as major high velocity entities widening to the south with depth until 6 km these fast anomalies are related to the sheeted dike complexes along the rifts on a finer scale slow anomalies suggest the presence of magma pockets centered at 0 2 km depth beneath mauna ulu makaopuhi and puu oo along the east rift zone erz two significant high velocity regions along the lower erz near kalalua and kaliu are inferred to represent intrusive barriers to magma injection along the shallow 0 4 km erz conduit the southwest rift zone may have an intrusive barrier related to a high velocity region just southwest of mauna iki the hilina and kaoiki fault zones are imaged as slow features at shallow depths 5 km related to the open fractures and scarps along the normal faults the koae fault system is imaged as a slightly fast shallow structure 6 km possibly related to intrusive diking from the adjacent rift zones that fill and may even induce the extensional structures associated with this complex fault zone continued inversions with the immense amount of seismic data collected for hawaiian events will allow the detailed development of a three dimensional structural model for kilauea such a model will be extremely useful to seismologists and petrologists alike for understanding the tectonic growth and magmatic evolution of this dynamic shield volcano

rare earth element trends and cerium uranium manganese associations in weathered rock from koongarra northern territory australia at koongarra australia three drill cores form the cahill schist formation containing u ore and regolith above it containing secondary u ore were studied to ascertain the distribution of rare earth elements rees and u the unaltered schist has a ree trend similar to the post archaean australian shale paas which is therefore used as a normalising standard unweathered rock from the zone of primary u mineralisation contained strong enrichment of the heavy rees and this pattern is retained during most of the weathering strongly bleached and very weathered shallow samples from this zone do not show enrichment of hrees in general however weathering appears to have little effect on the pattern of rees in the bulk rock at this site zones rich in mn oxy hydroxides occurring as coatings on fissure surfaces contain large concentrations of ce and u with a clear ce anomaly ce ce 3 8 the ce and u apparently occur together as microcrystalline oxides within 1 2 mu m diameter globules on mineral surfaces in the mn rich zones 46 refs 10 figs 2 tabs