styles of failure in late holocene highstand prodelta wedges on the adriatic shelf on the continental shelves of the northern mediterranean basin the late holocene highstand systems tract hst prograded un der the influence of major rivers after the attainment of the present sea level highstand about 5 5 cal kyr bp on the adriatic shelf the thickness distribution of the late holocene hst reflects the location of major deltas on the western side of the basin and the geostrophic cir culation which prevents a more uniform sediment dispersal toward the center of the basin very high sediment accumulation rates 1 to 10 cm year resulted in the construction of a hst depocenter up to 35 m thick this shore parallel depocenter is affected by failure of limited displacement over as much as 40 of its extent gas impregnation is common in the topset region and occurs at very shallow levels a few meters below the sea floor five areas are characterized by a variety of sea floor and subsurface crenulations although locally some of these crenulations have an intriguingly regular geometry sediment failure is the most plausible mechanism for their formation sediment failure better explains the large variety of geometries that characterizes the coastal mud prism of the late holocene hst furthermore we observe that these crenulations occur only where the downlap surface at the base of the hst is disrupted and affected by geometries that are con sistent with fluid escape processes this relationship suggests that the basal surface acts as a weak layer for sediment failure failure occurred in variable water depths from the northern slope of the modern po prodelta 10 20 m water depth to the narrow shelf offshore bari 40 110 m water depth in all these areas the proximal part of the hst prodelta wedge is intensely gas charged the thickness and age of the sediment sections affected by failure are slightly differ ent from place to place but appear everywhere younger than 5 5 cal kyr bp where failure affects the entire hst the detachment occurs on the downlap surface at its base failure geometries characterize the head region whereas compressional features such as pressure ridges and mud diapirs dominate in the toe region ranging in depth between 70 and 110 m where failure is limited to the upper few meters of the hst there is a clear lithologic change decrease in carbonate fraction and grain size across the basal surface this lithological change reflects a switch in sediment supply from local apennine rivers below to po derived mud this change occurred at the onset of the little ice age documenting the indirect control of short term climate change and hu man impact on sediment architecture the deformations affecting the late holocene hst in the various areas show differences in internal geometry but appear everywhere to be characterized by limited downward displacement and can be attri buted to shear dominated retrogressive failure it is suggested that some degree of consolidation occurred immediately after mobilization possibly induced by the escape of fluids nowhere has failure evolved into disintegration and flow likely because the type of cyclic loading that triggered it was not prolonged over a long enough interval short lived radionuclides in the uppermost stratigraphic layers which postdate the failure in the area offshore ortona allowed us to quantify systematic changes in sediment accumulation rates as a func tion of the underlying deformed sea floor in areas of wavy sea floor troughs show sediment accumulation rates of greater than 16 mm yr a figure that is fourfold the rate measured on the flanks of the troughs

the formation of large mudwaves by turbidity currents on the levees of the toyama deep sea channel japan sea the development of mudwaves on the levees of the modern toyama deep sea channel has been studied using gravity core samples combined with 3 5 khz echosounder data and airgun seismic reflection profiles the mudwaves have developed on the overbank flanks of a clockwise bend of the channel in the yamato basin japan sea and the mudwave field covers an area of 4000 km2 mudwave lengths range from 0 2 to 3 6 km and heights vary from 2 to 44 m and the pattern of mudwave aggradation indicates an upslope migration direction sediment cores show that the mudwaves consist of an alternation of fine grained turbidites and hemipelagites whereas contourites are absent core samples demonstrate that the sedimentation rate ranged from 10 to 14 cm ka 1 on the lee sides to 17 40 cm ka 1 on the stoss sides a layer by layer correlation of the deposits across the mudwaves shows that the individual turbidite beds are up to 20 times thicker on the stoss side than on the lee side whereas hemipelagite thicknesses are uniform this differential accretion of turbidites is thought to have resulted in the pattern of upcurrent climbing mudwave crests which supports the notion that the mudwaves have been formed by spillover turbidity currents the mudwaves are interpreted to have been instigated by pre existing large sand dunes that are up to 30 m thick and were created by high velocity 10 ms 1 thick c 500 m turbidity currents spilling over the channel banks at the time of the maximum uplift of the northern japan alps during the latest pliocene to early pleistocene draping of the dunes by the subsequent lower velocity 10 1ms 1 mud laden turbidity currents is thought to have resulted in the formation of the accretionary mudwaves and the pattern of upflow climbing the dune stoss slopes are argued to have acted as obstacles to the flow causing localized loss of flow strength and leading to differential draping by the muddy turbidites with greater accretion occurring on the stoss side than on the lee slope the two overbank flanks of the clockwise channel bend show some interesting differences in mudwave development the mudwaves have a mean height of 9 8 m on the outer bank levee and 6 2 m on the inner bank the turbidites accreted on the stoss sides of the mudwaves are 4 6 times thicker on the outer bank levee than their counterparts on the inner bank levee these differences are attributed to the greater flow volume thickness and sediment flux of the outer bank spillover flow due to the more intense stripping of the turbidity currents at the outer bank of the channel bend differential development of mudwave fields may therefore be a useful indicator in the reconstruction of deep sea channels and their flow hydraulics

the use of 7 lioh impregnated filters for the collection of acidic gases and analysis by instrumental neutron activation analysis a simple system was designed using7lioh impregnated filters to collect acidic gases from ambient air and from highly concentrated volcanic plumes or gas streams these filters were developed for analysis using instrumental neutron activation analysis but other analytical techniques could be used as well the sampling system was designed to use a series of 1 3 m7lioh impregnated filters to collect high concentrations of acidic gases found in gas plumes of active volcanoes the filters are quantitative for so2 and the halide acids when sufficient base is present to neutralize the acidic species extremely high concentrations of so2 may not be collected quantitatively since so2 is a relatively weak lewis acid compared to the halide acids the acidic oxides of sb as and se were also collected quantitatively a particle filter preceded the impregnated filters in order to remove particles from the fumes this system has proven effective under difficult sampling conditions and since it is portable and light weight it could be used for many volcanological applications where high levels of acidic gaseous phase species need to be collected

emission of bromine and iodine from mount etna volcano 1 constraining fluxes of volcanic bromine and iodine to the atmosphere is important given the significant role these species play in ozone depletion however very few such measurements have been made hitherto such that global volcanic fluxes are poorly constrained here we extend the data set of volcanic br and i degassing by reporting the first measurements of bromine and iodine emissions from mount etna these data were obtained using filter packs and contemporaneous ultraviolet spectroscopic so2 flux measurements resulting in time averaged emission rates of 0 7 kt yr 1 and 0 01 kt yr 1 for br and i respectively from april to october 2004 from which we estimate global br and i fluxes of order 13 range 3 40 and 0 11 range 0 04 6 6 kt yr 1 observed changes in plume composition highlight the coherent geochemical behavior of hcl hf hbr and hi during magmatic degassing and strong fractionation of these species with respect to so2

construction of the pyreneo languedocian sedimentary ridge and associated sediment waves in the deep western gulf of lions western mediterranean migrating sediment waves have been recognized in a wide range of marine settings including turbidite levees adjacent to submarine canyons and valleys the pyreneo languedocian sedimentary ridge plsr located in the gulf of lions north western mediterranean appears similar to such a levee in an attempt to understand the construction of both the plsr and associated sediment waves several scale studies were done the data include high and medium resolution seismic reflection profiles and cores collected both on upslope and downslope sides of two successive waves at a regional scale the situation of the plsr was strongly influenced by pliocene salt tectonics movements that resulted in a basin at the mouth of the catalano languedocian canyons later salt tectonics were chiefly inactive during quaternary and waves do not result of an extensive superficial tectonic activity at the scale of the plsr the construction occurred during the quaternary and is divided in three stages recognized on the basis of waves geometry sediment supplies changes and spillover source variations common sediment wave cross sections have been identified and suggest a turbidite or a gravity flow origin sedimentological lithostratigraphical and biostratigraphical studies focus on the last sea level rise and high stand period the results support the sediment wave initiation and the occurrence of sand transfers even during the more recent period sand layers and high sedimentation rates characterize the deposits on upstream flanks lower rates of deposition correspond with downstream flanks

sulphur dioxide particle and elemental emissions from mount etna italy during july 1987 sulphur dioxide emission rates were measured at mount etna italy during july 1987 while the volcano was undergoing relatively quiet activity the so2 flux averaged 930 587 1 mg d excluding 19 july when the flux was 3200 1730 1 mg d rising magma and or an influx of less degassed magma could explain the increased so2 flux the high so2 flux did not correlate with changes in observed volcanic activity this suggests that so2 monitoring may be useful as an indicator of shallow magmatic activity but not as a predictor of future eruptions of mount etna

a walk down the cap de creus canyon northwestern mediterranean sea recent processes inferred from morphology and sediment bedforms the cap de creus canyon northwestern mediterranean sea belongs to a complex network of submarine canyons cutting the western gulf of lion continental shelf and opening into the larger sete canyon swath bathymetry data mak 1m deep towed side scan sonar imagery and 5 khz high resolution seismic reflection profiles show striking morphologies in the cap de creus canyon floor and walls as a consequence of the canyon head and the upper reach severe incision the continental shelf dramatically narrows in front of the creus cape promontory the upper canyon has a flat bottomed thalweg incised in a mega scale sediment furrow field displaying hyperbolic seismic facies the tens of kilometres long linear furrows extend also over the middle canyon down to 1400 m of water depth the furrows on either side of the canyon are not parallel but oblique and display varying degrees of excavation mid channel sediment bars are locally present in the thalweg which is made of sandy lag deposits as revealed by its acoustic response and verified by sediment samples the middle canyon is linear and steep with an up to 700 m high southern wall contrasting with the sinuous smooth lower canyon which is controlled by flowage of the underlying messinian evaporites large sections of the canyon are affected by sediment instability processes the lower cap de creus canyon hangs up to 260 m over its distalmost reach and the sete canyon through a narrow less than 1 km wide gorge numerous scours up to 10 m deep suggesting bed load transport occupy the lower sete canyon immediately downstream of the cap de creus canyon mouth the data set provides the first complete very high resolution imaging of a submarine canyon from its upper part down to its distalmost reach the observations evidence a wide set of erosion transport and deposition processes along the cap de creus canyon including sediment entrapment at the canyon head furrow generating dense water cascading through the southern wall along channel currents strong enough to excavate specific sections of the channel floor and bed load sediment transport as demonstrated by the presence of mega ripples crescent scours and grooves in the lower canyon

the newest developments of load unload response ratio lurr the load unload response ratio lurr method is an intermediate term earthquake prediction approach that has shown considerable promise it is inspiring that its predictions using lurr have been improving since 2004 we have made a major breakthrough in intermediate term earthquake forecasting of the strong earthquakes on the chinese mainland using lurr and successfully predicted the pakistan earthquake with magnitude m 7 6 on october 8 2005 the causes for improving the prediction in terms of lurr have been discussed in the present paper

metal transport in volcanic plumes a case study at white island and yasur volcanoes abstract we report new data on trace metal emissions at white island volcano 2015 2016 the first estimates from yasur volcano 2016 and a brief review of global volcanic metal fluxes bi cd tl se sb te and au are the most enriched metals and metalloids in the particulate phase of volcanic plumes observations of the particulate phase from the volcanic plumes of white island yasur and etna reveal abundant silicates and sulfates sulfuric acid and more interestingly zn oxide containing variable amounts of cu thermodynamic speciation calculations show chloride species to be very important in terms of gaseous metal transport complexation with sulfur in contrast appears significant only in s rich and cl poor gases at high 700 c temperature bromine despite being a minor component of volcanic gases is very efficient at complexing with metals and especially with cu pb bi zn and cr metal emission rates in the study period at white island are one to two orders of magnitude lower than reported previously with 6 10 kg d of cu as se and zn and

geotechnical characteristics and slope stability in the gulf of cadiz abstract sedimentological and geotechnical analyses of thirty seven core samples from the gulf of cadiz continental margin were used to define the regional variability of sediment properties and to assess slope stability considering the sediment property data set as a whole there is an association between grain size plasticity and water content any one of these properties can be mapped regionally to provide an indication of the dominant surface sediment lithology based on static sediment strength a simplified slope stability analysis showed that only steep slopes 16 for even the most vulnerable sediment can fail under static loading conditions accordingly transient loads such as earthquakes or storms are needed to cause failure on more moderate slopes a regional seismic slope stability analysis of the cadiz margin was performed based on detailed geotechnical testing of four gravity core samples the results showed that the stability of these slopes under seismic loading conditions depends upon sediment density the cyclic loading shear strength the slope steepness and the regional seismicity sediment density and cyclic loading shear strength are dependent upon water content which can act as a proxy for plasticity and texture effects specifically sediment in the water content range of 50 56 is most vulnerable to failure under cyclic loading within the cadiz margin as a result for a uniform seismicity over the region susceptibility to failure during seismic loading conditions increases with increasing slope steepness and is higher if the sediment water content is in the 50 56 range than if it is not the only sampled zone of failure on the continental slope contains sediment with water content in this critical range storm wave induced instability was evaluated for the continental shelf the evaluation showed that a storm having hundreds of waves with a height in the range of 16 m might be capable of causing failure on the shelf however no sediment failures were observed on the shelf that might have been caused by this mechanism

post glacial persistence of turbiditic activity within the rhone deep sea turbidite system gulf of lions western mediterranean linking the outer shelf and the basin sedimentary records emplacement of post glacial turbidites is commonly controlled by rapid changes in sea level or by seismicity on the continental rise of the gulf of lions western mediterranean an aseismic area we identified turbiditic beds deposited during the rising stage and highstand of sea level swath bathymetry sediment cores in situ cone penetrating tests cptu heavy mineral associations and radiocarbon dating determined the source composition distribution and age of the turbiditic beds turbidites are composed of homogeneous to positively graded silts to medium sand with quartz up to 90 shell debris and shelfal benthic faunas their distribution on the sea floor is very patchy and controlled by abundant inherited erosional bedforms their source is found in relict regressive sands at the outershelf their deposition occurred just after the onset of the post glacial sea level rise and the concomitant sediment starvation of the rhone deep sea turbiditic system until recently whilst canyons are fed with sand by strong seasonal hydro sedimentary dynamics on the outershelf the emplacement of post glacial turbidites is not controlled by sea level changes but probably by the periodic flushing of the canyons our study revealed that this low energy aseismic margin undergoes significant transport of sand down to the base of slope during the sea level rise and the holocene highstand

kurile island arc volcanism structural and petrological aspects abstract this study discusses the structural and spatial characteristics of all known kurile island arc quaternary volcanoes which include 105 that are subaerial and 96 submarine volcanic activity in the island arc is distributed in two zones parallel to the kurile kamchatka deep sea trench the depth to the seismo focal zone in the frontal zone is 110 140 km and in the rear zone 160 190 km these frontal and rear volcanic zones show distinct variations in geochemical petrologic and mineralogic characteristics concentrations of k rb ba sr f be la ce nb zr u th ni and cr in similar volcanic rocks of the rear zone are typically more than twice as high as those in rocks of the frontal zone whereas concentrations of fe and v are half as high in the rear zone lavas as in those of the frontal zone variations in concentration along the strike of the arc are less pronounced the average 87 sr 86 sr ratios for the frontal and rear zones are northern kuriles 0 70322 and 0 70304 middle kuriles 0 70302 and 0 70295 and southern kuriles 0 70347 and 0 70306 respectively 143 nd 144nd values in lavas from the frontal and rear zones are 9 10 and 7 8 respectively be abundances in the kurile island arc lavas range from 2 2 10 6 at g to 7 9 10 6 at g no differences in 10 be abundances corresponding to the frontal and rear arc zones have been found acid and intermediate lavas from the volcanic front are characterized by a two pyroxene phenocryst association while similar lavas from the rear arc have amphibole and biotite bearing associations mineral compositions plagioclase pyroxene amphibole olivine in the two zones also show distinct differences plagioclase in the rear arc lavas is less calcic with higher k sr ba and lower fe than in the frontal lavas ferromagnesian minerals in the rear arc lavas contain less fe and more mg than in frontal lavas these data are used to develop a model for magma generation related to two levels of volatile separation from the subducting lithospheric plate

middle miocene mound shaped sediment packages on the slope of the xisha carbonate platforms south china sea combined result of gravity flow and bottom current deep water mound shaped sediment packages on the northern slope of the xisha carbonate platforms in the northern south china sea were analyzed by integrating high resolution multi channel seismic and drilling data the mounds are distributed in the beijiao depression of the qiongdongnan basin within the t41 t40 seismic horizons which correspond to the middle miocene mound shaped reflections were identified both in the ne sw and nw se oriented seismic profiles the mound shapes are most prominent in the center of the nw se oriented seismic profiles and the undulating tops flatten out towards the nw and se similar reflections are mostly asymmetric with steeper eastern flanks in the ne sw oriented seismic profiles and they are mostly round in shape the wave impedance from the inversion calculation is 6 8 x 10 6 kg m 2 s it is much lower than that of the reef reservoir in the lh11 1 reef oilfield paleogeographic analysis shows that the xisha uplift was dominated by tropical shallow carbonate platforms while the beijiao depression became a bathyal environment in the middle miocene drilling data confirmed that the mound shaped sediment packages are mainly composed of calcareous mudstone therefore we infer that the mound shaped sediment packages could be reef complexes or they were presumably built by combined gravity flow and bottom current c 2015 elsevier ltd all rights reserved

rates of sulfur dioxide and particle emissions from white island volcano new zealand and an estimate of the total flux of major gaseous species airborne correlation spectrometry cospec was used to measure the rate of so2 emission at white island on three dates i e november 1983 1230 300 t d november 1984 320 120 t d and january 1985 350 150 t d t metric tons the lower emission rates are likely to reflect the long term emission rates whereas the november 1983 rate probably reflects conditions prior to the eruption of december 1983 the particle flux in the white island plume as determined with a quartz crystal microbalance cascade in november 1983 was 1 3 t d unusually low for volcanic plumes the observed plume particles as shown from scanning electron microscopy include halite native sulfur and silicates and are broadly similar to other volcanic plumes

variation of deepwater convection in the western mediterranean sea gulf of lion during the last 28 ka abstract the oxygen and carbon isotopes record from fossil foraminifera in deep sea sediments are commonly used as proxy for global thermohaline and productivity changes the last 28 ka record of oxygen and carbon isotopes are characterized by a slow transfer of isotopic signal from surface to deep mediterranean at the beginning of heinrich events h2 and h1 and during the bolling allerod these changes in deep waters properties occur some 180 years later indicating a decrease of ventilation in the beginning of these events the slowing of the thermohaline convection is more marked in the early holocene characterized by less than 500 years of lag time between the isotopic signals

volatilization transport and sublimation of metallic and non metallic elements in high temperature gases at merapi volcano indonesia abstract condensates silica tube sublimates and incrustations were sampled from 500 800 c fumaroles and lava samples were collected at merapi volcano indonesia in jan feb 1984 with respect to the magma merapi gases are enriched by factors greater than 105 in se re bi and cd 104 105 in au br in pb and w 103 104 in mo cl cs s sn and ag 102 103 in as zn f and rb and 1 102 in cu k na sb ni ga v fe mn and li the fumaroles are transporting more than 106 grams day g d of s cl and f 104 106 g d of al br zn fe k and mg 103 104 g d of pb as mo mn v w and sr and less than 103 g d of ni cu cr ga sb bi cd li co and u with decreasing temperature 800 500 c there were five sublimate zones found in silica tubes 1 cristobalite and magnetite first deposition of si fe and al 2 k ca sulfate acmite halite sylvite and pyrite maximum deposition of cl na k si s fe mo br al rb cs mn w p ca re ag au and co 3 aphthitalite k na sulfate sphalerite galena and cs k sulfate maximum deposition of zn bi cd se and in higher deposition of pb and sn 4 pb k chloride and na k fe sulfate maximum deposition of pb sn and cu and 5 zn cu and k pb sulfates maximum deposition of pb sn ti as and sb the incrustations surrounding the fumaroles are also chemically zoned bi cd pb w mo zn cu k na v fe and mn are concentrated most in or very close to the vent as expected with cooling atmospheric contamination and dispersion the highly volatile elements br cl as and sb are transported primarily away from high temperature vents ba si p al ca and cr are derived from wall rock reactions incomplete degassing of shallow magma at 915 c is the origin of most of the elements in the merapi volcanic gas although it is partly contaminated by particles or wall rock reactions the metals are transported predominantly as chloride species as the gas cools in the fumarolic environment it becomes saturated with sublimate phases that fractionate from the gas in the order of their equilibrium saturation temperatures devolatilization of a cooling batholith could transport enough acids and metals to a hydrothermal system to play a significant role in forming an ore deposit however sublimation from a high temperature high velocity carrier gas is not efficient enough to form a large ore deposit re se cd and bi could be used as supporting evidence for magmatic fluid transport in an ore deposit

size resolved chemical composition of aerosol emitted by erebus volcano antarctica 1 persistent open vent degassing of erebus volcano antarctica is a significant point source of gases and aerosol to the austral polar troposphere we report here on the chemical composition and size distribution of the erebus aerosol focusing on the water soluble fraction the aerosol was sampled at the rim of the active crater using a cascade impactor which collected and sized particles in 14 size bins from 10 to 0 01 m the soluble fraction of the erebus aerosol is distinct from other volcanic sources in several respects it is dominated by chloride bearing particles over 30 of total mass and has an unusually high cl so42 molar ratio of 3 5 coarse particles contribute little to the total mass of the soluble fraction elevated concentrations of f cl br and so42 are found in a narrow particle size fraction of 0 1 0 25 m the detection of particulate br reinforces our understanding of the potential for quiescent volcanic emissions to deplete tropospheric ozone the small aerosol size reflects the low atmospheric temperature and humidity which inhibit particle growth halide alkali metal salts na k cl f appear to be the most abundant species in the aerosol the concentration of pb is high compared to other volcanoes its exsolution may be promoted by the high abundance of halogens in erebus magma despite the previously reported high nox content in the plume we did not detect significant quantities of nitrate in the near vent aerosol our findings emphasize the potential regional significance of emissions from erebus for understanding the antarctic atmospheric composition and glaciochemical records

volcanic emissions of metals and halogens from white island new zealand and erebus volcano antarctica determined with chemical traps abstract volcanic emission rates of as sb pb hg se cl and f were determined at erebus volcano antarctica and white island new zealand using chemical traps the trace metal fluxes were determined by combining the species to s ratios in the solutions with so2 emission rates measured by correlation spectrometry at the two volcanoes at erebus volcano fluxes for the metals pb and hg were 2 0 10 4 and 8 1 10 6 kg s 11 respectively fluxes for cl f as sb and se 0 35 0 15 2 5 10 4 1 2 10 5 and 4 5 10 6 kg s 1 respectively agreed within error limits for values determined previously by the lioh impregnated filter method zreda gostynska g kyle p finnegan d prestbo k 1997 volcanic gas emissions from mount erebus and their impact on the antarctic environment journal of geophysical research 102 b7 15039 15055 demonstrating the utility of the chemical trap method a fall in the as s ratio from 7 10 4 in 1997 1999 to 3 10 4 in 2000 at erebus coincided with a change in the frequency and style of eruptive activity that may have been due to injection of magma into the system at white island chemical trap data indicated fluxes of cl 0 90 f 0 0079 pb 2 7 10 4 hg 1 1 10 5 as 1 3 10 4 sb 1 9 10 5 and se 1 5 10 5 kg s 1 samples collected 600 m downwind of the active crater were comparable to samples collected adjacent to the main gas vent showing that this method can still be used at some distance from a degassing vent

the significance of grain size breaks in turbidites and pyroclastic density current deposits turbidite beds and pyroclastic density current deposits commonly show abrupt internal changes in grain size with stepwise upward fining grain size breaks divide a turbidite bed into a lower sandy zone a middle silty zone and an upper muddy zone zone boundaries need not correspond with bouma division boundaries but the sandy zone usually consists of a b and occasionally c divisions the silty zone is composed of one or more of the b c and d divisions and the muddy zone correlates with division e pyroclastic density current deposits likewise display a tripartite zonation with prominent grain size breaks divergence of particle laden gravity currents into a lower dense body and an upper dilute turbulent wake can explain the formation of the lower grain size break fine particles are elutriated into the wake region by ambient entrainment through the current head while coarse grains are transported in the body particle size and concentration stratification is sustained by the turbulence and velocity structure of gravity currents with a velocity maximum and turbulence minimum also dividing currents into two regions two stages of deposition result the upper grain size break may be produced by buoyant lofting with fine particles convected into the water column or atmosphere as the flow wanes

channel related sediment waves on the eastern slope offshore dongsha islands northern south china sea abstract the characteristics and origin of the sediment waves on the eastern slope offshore dongsha islands northern south china sea scs were analyzed by integrating high resolution multibeam bathymetric seismic and piston core data four sediment wave fields were identified which are the west dongsha channel wdsw west taiwan channel wtsw south taiwan channel stsw and west penghu channel wpsw sediment wave fields respectively they are distributed on the right levees looking downstream and adjacent overbank areas of related channels wdsw wtsw and stsw or developed outside the channel mouths wpsw each sediment wave field consists of several to tens of rows of sediment waves these sediment waves are up to 2 8 7 2 km in wavelength and 30 60 m in wave height with wave crests orthogonal to or oblique to the orientation of the channels the sediment waves gradually decrease in dimension both in downslope direction and with the distance increasing away from the channel most sediment waves are asymmetric in cross sections with a thicker upslope flank and a thinner downslope flank and therefore migrate upslope piston cores suggest that sandy turbidites developed with normal size grading dominate the channels while massive muds with thin sandy or silty turbidite interbeds prevail in the inter channel regions on which the sediment waves situated the sediment waves on the channel levees and related overbank areas wdsw wtsw and stwd were presumably built by the turbidity currents overspilled from the channels while those in wpsw located outside the mouth of the west penghu channel are suggested generated by unconfined sheet like turbidity currents outside the channel mouth

melt inclusion investigation of the volatile behaviour in historic alkali basaltic magmas of etna crystallization paths of basaltic 1763 eruption and hawaiitic 1865 and 1329 eruptions scoria from etna were deduced from mineralogy and melt inclusion chemistry the volatile behaviour was investigated through the study of melt inclusions trapped in the phenocrysts and those of the whole rocks and the matrix glasses the results from the 1763 eruption point to the early crystallization of olivine fo 81 7 from a water rich alkaline basalt with high cl 1750 2000 ppm and s 2100 2400 ppm concentrations the hawaiitic melt inclusions trapped in olivine fo 74 salite and plagioclase are characterized by a decrease in cl k2o and s k2o ratios in each investigated system there is good correlation between k2o and p2o5 in the whole rocks cl ranges from 980 to 1680 ppm from basaltic to hawaiitic lavas whereas s 110 136 ppm remains low cl and s behaviour in the 1763 magma suggests an early degassing stage of cl and s with co2 and a water rich gaseous phase for a pressure close to 100 mpa consistent with a permanent outgassing at the summit craters of etna during the eruption the sulphur remaining in the hawaiitic liquid is lost and the degassing of chlorine is limited such a degassing model can be extended to the 1865 and 1329a d eruptions

three years of so2 flux measurements of mt etna using an automated uv scanner array comparison with conventional traverses and uncertainties in flux retrieval 1 sviluppo di sistemi di monitoraggio dipartimento di protezione civile della regione sicilia 2 ingv istituto nazionale di geofisica e vulcanologia sezione di catania italy 3 novac network for observation of volcanic and atmospheric change eu funded sixth framework programme project 18354 4 uk nerc national centre for earth observation via the dynamic earth and geo hazards

sea valleys and related depositional systems in the gulf of lion and ebro continental margins 1 four main types of sea valleys submarine canyons gullies channels of turbidite systems and a mid ocean channel have been characterized in the ebro and the gulf of lion distal margins in the catalan sea together with three main types of depositional bodies pyrenean canyon deep sedimentary body pcdsb apron deposits and channel levee complexes related to the development of these sea valleys erosion and deposition mainly during the quaternary have formed the majority of these sea valleys although some structurally controlled sea valleys also exist as an example a messinian entrenchment has been confirmed in the petit rhone canyon the evolution of the drainage patterns is established from the detailed analysis of the sedimentary structure this analysis revea s the presence of buried sedimentary bodies and older drainage systems differing from those observed in the bathymetric charts specific factors determine the evolutionary differences between both margins including the absence or presence of underlying evaporitic messinian layers and the regional geodynamic evolution during and after the alpine orogeny we propose a dual evolutionary model from the end of the miocene to the quaternary

silicate microspherules intercepted in the plume of etna volcano a possible volcanic origin has been suggested for the micrometre sized spherules that have been discovered in polar snows or ice cores1 5 and in the stratosphere6 7 however although such particles especially when black and magnetic have been identified among the tephra deposits of some volcanoes3 8 12 their volcanic emission has never been directly observed here we describe micro spherules intercepted in the plume of mount etna sicily during moderate recurring volcanic activity their study using analytical transmission and scanning electron microscopy atem and asem demonstrates the simultaneous presence in the plume of glassy silicate microspherules of various chemical compositions 47 98 sio2

recent sedimentary events in the western gulf of lions western mediterranean abstract analysis of very high resolution data 3 5 khz profiles and em12d acoustic imagery collected during the calmar catalono languedocian margin cruise 1997 highlighted the occurrence of two very recent but previously unknown erosional sedimentary events on the continental rise between the rhone fan and the pyreneo languedocian ridge these events preserved as unconformable very thin lobes observable on acoustic imagery but not on 3 5 khz echo soundings relate to erosional processes linked to near bottom currents that seem to characterize the holocene hydrodynamical conditions in the deep gulf of lions they follow a pleistocene regime when gravity sedimentation dominated on the gulf of lions margin either through aggradational turbidite deposition rhone fan and pyreneo languedocian ridge or through remobilization of sediments by regional mass movements processes

fractionation of families of major minor and trace metals across the melt vapor interface in volcanic exhalations chemical families of metals fractionate systematically as they pass from a silicate melt across the interface with the vapor phase and on into a cooled volcanic plume we measured three groups of metals in a small suite of samples collected on filters from the plumes of kilauea hawaii usa etna sicily and merapi java volcanoes these were the major minor and trace metals of the alkali and alkaline earth families k rb cs ca sr ba a group of ordinarily rare metals cd cu in pb tl that are related by their chalcophile affinities and the radon daughter nuclides 210po 210bi and 210pb the measurements show the range and some details of systematic melt vapor fractionation within and between these groups of metals in the plumes of all three volcanoes the alkali metals are much more abundant than the alkaline earth metals in the kilauea plume the alkali metals are at least six times more abundant than the alkaline earth metals relative to abundances in the melt at etna the factor is at least 300 fractionations within each family are commonly also distinctive in the kilauea plume in addition to the whole alkaline earth family being depleted the heaviest metals of the family sr ba are progressively more depleted than the light metal ca in plumes of fumaroles at merapi k cs ratios were approximately three orders of magnitude smaller than found in other earth materials this may represent the largest observed enrichment of the light ion lithophile lil metals changes in metal ratios were seen through the time of eruption in the plumes of kilauea and etna this may reflect degree of degassing of volatiles with which metals complex from the magma bodies at kilauea the changes in fractionation were seen over about three years fractionation within the alkaline earth family increased and that between the two families decreased over that time all of the ordinarily rare chalcophile metals measured are extremely abundant in volcanic plumes and cd and tl are enriched relative to the others indium is much more abundant in the plume of the hotspot volcano kilauea than in the etna plume probably non hotspot in character it may be a useful indicator of the tapping of deep mantle zones or could aid in the interpretation of reports of pt group metals in exhalations from hot spot volcanoes indium in old glacial ice strata could help assess magnitude and variability of exhalations from hotspot volcanoes in past time strong melt vapor fractionation of the alkali and alkaline earth metals may only be observed in plumes during quiescent degassing of volcanoes when large amounts of ash or spatter undifferentiated lava enter the plume its alkali and alkaline earth metal composition may approach that of the melt ratios among the chalcophile metals may not be much changed by addition of ash because their concentrations in melt are so small and masses of them in any plume may remain dominated by transfer across the melt vapor interface radon daughter nuclides give information about state of volcanic activity at time of sampling the precisely known origins ultratrace detectability decay systematics and wide variations in volatility of these species provide information about residence times degassing and travel histories and identities of melt bodies in volcanic systems

the role of sulfur in the formation of magmatic hydrothermal copper gold deposits abstract essential resources of many rare metals including copper zinc molybdenum silver and gold occur in natural sulfide mineral deposits understanding the origin of these metal resources has been limited by a lack of data about the geochemistry of sulfur the most important and abundant element of ore deposits we report the first directly measured sulfur concentrations in high temperature fluids together with their ore metal contents using a new method for sulfur quantification in fluid inclusions by laser ablation inductively coupled plasma mass spectrometry la icp ms co genetic brine and vapor inclusions from magmatic hydrothermal ore deposits and granitic intrusions show an excess of sulfur over ore metals as required for efficient ore mineral precipitation the results demonstrate that s cu and au are highly enriched in vapor like magmatic fluids implying that such low salinity fluids are the key agent for the formation of porphyry copper and epithermal gold deposits

distinguishing sediment waves from slope failure deposits field examples including the humboldt slide and modelling results abstract migrating sediment waves have been reported in a variety of marine settings including submarine levee fan systems floors of fjords and other basin or continental slope environments examination of such wave fields reveals nine diagnostic characteristics when these characteristics are applied to several features previously attributed to submarine landslide deformation they suggest that the features should most likely be reinterpreted as migrating sediment wave fields sites that have been reinterpreted include the humboldt slide on the eel river margin in northern california the continental slope in the gulf of cadiz the continental shelf off the malaspina glacier in the gulf of alaska and the adriatic shelf a reassessment of all four features strongly suggests that numerous turbidity currents separated by intervals of ambient hemipelagic sedimentation deposited the wave fields over thousands of years a numerical model of hyperpycnal discharge from the eel river for example shows that under certain alongshore current conditions such events can produce turbidity currents that flow across the humboldt slide serving as the mechanism for the development of migrating sediment waves numerical experiments also demonstrate that where a series of turbidity currents flows across a rough seafloor i e numerical steps sediment waves can form and migrate upslope hemipelagic sedimentation between turbidity current events further facilitates the upslope migration of the sediment waves physical modelling of turbidity currents also confirms the formation and migration of seafloor bedforms the morphologies of sediment waves generated both numerically and physically in the laboratory bear a strong resemblance to those observed in the field including those that were previously described as submarine landslides

large sediment waves over the gulf of roses upper continental slope nw mediterranean recently acquired swath bathymetry and seismic datasets on the gulf of roses continental slope revealed the presence of large sediment waves that have developed between 200 and 400 m water depth geometric parameters were computed from the multibeam dataset and the obtained results showed mean sediment wave lengths of 2000 m and maximum heights of 60 m the analysis of seismic profiles showed the general architecture of the late quaternary deposits over the gulf of roses outer shelf and slope the outer continental shelf is characterized by morphological erosional features affecting the upper part of the most recent seismic unit over the continental slope five main unconformity bounded seismic units are differentiated with sediment waves developed in all of them the sediment waves observed over the continental slope are presumably generated by bottom currents intensified during major dense shelf water cascading events flowing downslope at an oblique angle with respect to the main bathymetry

density cascading off shelf sediment transport evidence and implications bahama banks abstract suspended sediment concentrations in shelf waters are often appreciable but sediments on their own rarely contribute enough density to cause suspension currents to transport them offshelf however sediment charged hyperpycnal high density waters are often generated over continental shelves because of the same set of air sea interactions intense heat and moisture flux responsible for thermohaline production and circulation of deep ocean water masses we propose the term density cascading to describe the processes by which hyperpycnal waters are released from shelf areas and together with entrained sediments sink to their compensation level in the adjacent ocean density cascading probably involves a range of physical processes from pelagic draping of slopes and basins with shelf muds to initiating turbidity currents capable of scouring canyons and plunge pools sediment bypassing of slopes and deposition of sands in deep basins thermodynamic air sea interactions can generate hyperpycnal water at all latitudes therefore density cascading has important implications not only to the sedimentology of modern carbonate platforms such as the florida shelf and bahama banks and stratigraphy in ancient limestones but also to offshelf sediment flux in siliciclastic environments

abrupt climate change sea surface salinity and paleoproductivity in the western mediterranean sea gulf of lion during the last 28 kyr abstract the planktonic foraminiferal record of core md99 2346 gulf of lion shows a decrease of sea surface temperature sst at the time of heinrich event h2 24 23 5 cal kyr bp younger dryas and during the early to middle holocene these events were associated with a decrease of surface water salinity the salinity lowering events were similar and synchronous to those recorded in the north atlantic ocean during h1 h2 and the younger dryas they can be explained by a decrease in the salinity of the atlantic surface water entering the mediterranean through the strait of gibraltar this result indicates that the mediterranean sea remained a concentration basin and that its freshwater budget was not significantly different from the modern conditions at the time of these low salinity events higher abundances of the benthic foraminifer cibicidoides pachydermus at the time of heinrich events h2 and h1 may result from a seasonal and more pulsed supply of labile organic matter a high abundance of intermediate and deep infaunal taxa globobulimina spp during the warm bolling allerod period is interpreted as a result of an increased lateral advection of organic matter to the deeper environments of the gulf of lion surface water productivity as reflected by the organic flux to the benthic ecosystem reaches a maximum during the cold younger dryas period it is possible that cold conditions at the time of the younger dryas have allowed an enhanced vertical mixing and deep water cascading in the gulf of lion this may have resulted in an increase of primary and export production this putative intensification of deep water cascading would have occurred after the sustained rise of the global sea level from 16 to 12 5 cal kyr bp the deglacial sea level rise may also have played an important role in favouring the downslope movement of dense shelf water enriched in organic matter originating from the early rhone delta complex the conditions during the holocene were characterized by a low surface productivity and oligotrophic environment similar to the modern situation

variability of alkali and heavy metal fluxes released by mt etna volcano sicily between 1991 and 1995 abstract we regularly collected volcanic gases and aerosols at mt etna volcano over a long period 1991 1995 and measured their chemical composition by icp ms based on these data we present new evidence on the high volatility of both alkali and some heavy metals in contrast both lanthanides and actinides are not produced as significant gaseous compounds at magmatic temperatures and can be used as tracers of spattered materials all metals of each chemical family maintained systematic trends during the study period at both summit craters and effusive vents located in the valle del bove during the 1991 1993 eruption during the eruption we observed high metal enrichments at effusive vents these enrichments seem to be characteristic of the secondary degassing of a magma previously degassed under the summit area lower metal enrichments are recorded in aerosols sampled in summit crater plumes according to the primary degassing type occurring at these vents while a primary degassing type still occurs at both bocca nuova and voragine during the post eruptive period sud est crater exhibits a transition from primary to secondary type according to the variations of the volcanic activity level we confirm that the alkali metals fractionate systematically within their family as they cross the melt vapour interface the heavier members being always more enriched than the lighter ones in aerosols we also show that this fractionation is not related to the volcanic activity and the degassing type but seems to be a significant feature of the alkali family itself estimation of new emanation coefficients for rubidium caesium tin and thallium 0 07 0 15 0 50 and 21 respectively yields annual outputs around 1000 t yr 60 t yr 240 t yr and 1600 t yr respectively mount etna is a very important source of metals injected into the atmosphere contributing to the global volcanic budget about 16 for heavy metals and 19 for alkali metals in eruptive periods and only 2 and 4 respectively in quiet periods

investigation of thallium fluxes from subaerial volcanism implications for the present and past mass balance of thallium in the oceans abstract a suite of 34 volcanic gas condensates and particulates from kilauea hawaii mt etna and vulcano italy mt merapi indonesia white island and mt nguaruhoe new zealand were analysed for both tl isotope compositions and tl pb ratios when considered together with published tl pb abundance data the measurements provide globally representative best estimates of tl pb 0 46 0 25 and e 205 tl 1 7 2 0 for the emissions of subaerial volcanism to the atmosphere and oceans e 205 tl is the deviation of the 205 tl 203 tl isotope ratio from nist srm 997 isotope standard in parts per 10 000 compared to igneous rocks of the crust and mantle volcanic gases were found to have i tl pb ratios that are typically about an order of magnitude higher and ii significantly more variable tl isotope compositions but a mean e 205 tl value that is indistinguishable from estimates for the earth s mantle and continental crust the first observation can be explained by the more volatile nature of tl compared to pb during the production of volcanic gases whilst the second reflects the contrasting and approximately balanced isotope fractionation effects that are generated by partial evaporation of tl during magma degassing and partial tl condensation as a result of the cooling and differentiation of volcanic gases mass balance calculations based on results from this and other recent tl isotope studies were carried out to investigate whether temporal changes in the volcanic tl fluxes could be responsible for the dramatic shift in the e 205 tl value of the oceans at 55 ma which has been inferred from tl isotope time series data for ferromanganese crusts the calculations demonstrate that even large changes in the marine tl input fluxes from volcanism and other sources are unable to significantly alter the tl isotope composition of the oceans based on modelling it is shown that the large inferred change in the e 205 tl value of seawater is best explained if the oceans of the early cenozoic featured significantly larger tl output fluxes to oxic pelagic sediments whilst the sink fluxes to altered ocean crust remained approximately constant

a total volatile inventory for masaya volcano nicaragua nerc project magma dynamics at persistently degassing basaltic volcanoes a novel approach to linking volcanic gases and magmatic volatiles within a physical model ne f004222 1 and ne f005342 1

airborne aerosol measurements in the quiescent plume of mount st helens september 1980 atmospheric particulate matter and condensed volatile species were collected in the quiescent plume of mount st helens volcano in sept 1980 using air filter systems mounted aboard a nasa turbo prop p 3 aircraft concentrations of 27 elements were determined by instrumental neutron activation analysis and ion chromotagraphy the volatile elements cl br f zn w in s cd se sb hg as and au were enriched relative to bulk ash emitted during the earlier eruptions by factors of 50 to 20 000 particulate s concentrations were approx 3 mu g m sup 3 and accounted for 6 of the total plume sulfur gas phase hg concentrations were 2 5 to 16 ng m sup 3 fluxes of elements were estimated by normalizing elemental concentrations to the concurrently measured total sulfur flux emission rates vary from 3500 kg day for particulate cl to 3 kg day for au with substantial quantities of the enriched elements zn as hg sb se and cd also being released estimated global fluxes of these elements from volcanoes to the atmosphere are in reasonable agreement with other literature estimates

sweet chestnut castanea sativa leaves as a bio indicator of volcanic gas aerosol and ash deposition onto the flanks of mt etna in 2005 2007 sweet chestnut leaves castanea sativa collected from the flanks of mt etna volcano in 2005 2007 were analysed by inductively coupled plasma mass spectrometry to investigate the spatial and temporal variability of element concentrations the aim of this work was to determine whether these leaves are a bio indicator for volcanic gas aerosol and ash deposition and to gain new insights into the environmental effects of quiescent and eruptive volcanic plumes results show a positive correlation between sample variability in the concentration of elements in castanea sativa and enrichment factors of elements in the plume the spatial and temporal variability of chalcophilic elements as cd cu mo tl zn is consistent with prevailing winds transporting eruptive plumes to the south east of the summit resulting in enhanced plume deposition onto the flanks of the volcano similar spatial and temporal variability was found for the halide forming elements cs k rb and intermediate elements al co mn the spatial variability of chalcophilic intermediate and halide forming elements during quiescent periods was diminished relative to eruptive periods and could not be explained by plume deposition in contrast the concentrations of lithophilic elements ba ca mg sr did not show any clear spatial variability even during eruptive periods comparisons between enrichment factors for elements in castanea sativa and literature values for enrichment factors of the volcanic plume groundwater and lichen were made whilst castanea sativa offers insights into the spatial and temporal variability of deposition the species may not be a bio indicator for plume composition due to biological fractionation

evaluation of gases condensates and so2 emissions from augustine volcano alaska the degassing of a cl rich volcanic system after the march april 1986 explosive eruption a comprehensive gas study at augustine was undertaken in the summers of 1986 and 1987 airborne cospec measurements indicate that passive so2 emission rates declined exponentially during this period from 380 45 metric tons day t d on 7 24 86 to 27 6 t d on 8 24 87 these data are consistent with the hypothesis that the augustine magma reservoir has become more degassed as volcanic activity decreased after the spring 1986 eruption gas samples collected in 1987 from an 870 c fumarole on the andesitic lava dome show various degrees of disequilibrium due to oxidation of reduced gas species and condensation and loss of h2o in the intake tube of the sampling apparatus thermochemical restoration of the data permits removal of these effects to infer an equilibrium composition of the gases although not conclusive this restoration is consistent with the idea that the gases were in equilibrium at 870 c with an oxygen fugacity near the ni nio buffer these restored gas compositions show that relative to other convergent plate volcanoes the augustine gases are very hcl rich 5 3 6 0 mol hcl s rich 7 1 mol total s and h2o poor 83 9 84 8 mol h2o values of d and 18o suggest that the h2o in the dome gases is a mixture of primary magmatic water pmw and local seawater part of the cl in the augustine volcanic gases probably comes from this shallow seawater source additional cl may come from subducted oceanic crust because data by johnston 1978 show that cl rich glass inclusions in olivine crystals contain hornblende which is evidence for a deep source 25km for part of the cl gas samples collected in 1986 from 390 642 c fumaroles on a ramp surrounding the inner summit crater have been oxidized so severely that restoration to an equilibrium composition is not possible h and o isotope data suggest that these gases are variable mixtures of seawater fmw and meteoric steam these samples are much more h2o rich 92 97 h2o than the dome gases possibly due to a larger meteoric steam component the 1986 samples also have higher cl s s c and f cl ratios which imply that the magmatic component in these gases is from the more degassed 1976 magma thus the 1987 samples from the lava dome are better indicators than the 1986 samples of degassing within the augustine magma reservoir even though they were collected a year later and contain a significant seawater component future gas studies at augustine should emphasize fumaroles on active lava domes condensates collected from the same lava dome fumarole have enrichments ot 107 102 in cl br f b cd as s bi pb sb mo zn cu k li na si and ni lower temperature 200 650 c fumaroles around the volcano are generally less enriched in highly volatile elements however these lower termperature fumaroles have higher concentration of rock forming elements probably derived from the wall rock