the genesis of late hercynian granitoids from galicia northwestern spain inferences from ree studies two mica granites and biotite rich monzogranites and granodiorites constitute the main types of late to post kinematic hercynian intrusions in galicia northwestern iberian massif both rock types exhibit analogous total ree content although the two mica granites have generally more fractionated normalized spectra the hercynian granites studied can be modeled as partial melts which in some cases experienced feldspar dominated fractional crystallization model source materials may be compared to the rocks outcropping in the area studied these granites are not accurately described by the i and s type classification those with s type characteristics two mica granites are derived mainly from an orthogneiss rich model protolith i e i type source whereas those with i type affinities biotite rich granitoids may be modeled from mixtures of orthogneiss and graywacke eastern galicia or from orthogneiss rich protoliths containing only a small proportion of metabasite western galicia the propose

sulfur diffusion in basaltic melts abstract we measured the diffusion coefficients of sulfur in two different basaltic melts at reduced conditions i e in the sulfide stability field temperatures from 1225 c to 1450 c pressures of 0 5 and 1 gpa and water concentrations of 0 and 3 5 wt although each melt is characterized by slightly different sulfur diffusion coefficients the results can be combined to create a general equation for sulfur diffusion in anhydrous basalts d 2 19 10 4 exp 226 3 58 3 r t where d is the diffusion coefficient in m2s 1 the activation energy is in kj mol 1 r is the gas constant and t is the temperature in k sulfur diffusion in basalts with 3 5 wt water is a factor of three to seven higher than in anhydrous melts and can be described by d 5 91 10 7 exp 130 8 82 6 r t at the conditions of this study the pressure does not measurably affect sulfur diffusion sulfur diffusion in dry basaltic melts is one order of magnitude higher than sulfur diffusion in dry andesitic and dacitic melts whereas sulfur diffusion in hydrous basaltic and andesitic melts is within the same order of magnitude when compared to the diffusivity of other volatile species in nominally dry basaltic melts sulfur diffusion appears to be two times lower than co2 diffusion and two orders of magnitude lower than h2o diffusion

the classification of micrometeorites due to their small size the mineralogical and chemical properties of micrometeorites mms are not representative of their parent bodies on the centimeter to meter scales that are used to define parent body groups through the petrological study of meteorites identifying which groups of mm are derived from the same type of parent body is problematic and requires particles to be rigorously grouped on the basis of mineralogical textural and chemical properties that reflect the fundamental genetic differences between meteorite parent bodies albeit with minimal bias towards preconceived genetic models specifically the interpretation of mms requires a rigorous and meaningful classification scheme at present the classification of mms is however at best ambiguous a unified petrological chemical classification scheme is proposed in the current study and is based on observations of several thousand mms collected from antarctic ice

relationship between petrologic processes in the plumbing system of mt etna and the dynamics of the eastern flank from 1995 to 2005 abstract mt etna volcano is located in a complex tectonic setting with large sectors of its eastern flank sliding seaward at different rates according to recent petrologic studies the etna s plumbing system has a multifaceted geometry variable in space and time and consisting of storage zones at different depths where magma ascending to the surface undergoes various processes mainly fractional crystallization and mixing in this framework we investigated a possible cause effect relationship between the flank displacement and pre eruptive magmatic processes in the shallow plumbing system furthermore a comparison between petrologic data and deformative patterns evidences that from 1995 to july 2001 the aforementioned pre eruptive magmatic processes did not significantly influence the volcano eastern flank dislocation which stayed slow and fairly regular by contrast the onset of the 2001 flank eruption leads to an acceleration of the movement as a consequence of the ascent of a primitive volatile rich sub aphyric basaltic magma from a deeper about 10 km b s l reservoir during the 2001 and 2002 03 activity at least for the decade 1995 2005 pre eruptive magmatic processes in the shallow portion

birth growth and morphologic evolution of the laghetto cinder cone during the 2001 etna eruption we have undertaken detailed observations of the formation of the laghetto cinder cone a new cone that formed during a 2 week period of intense activity in piano del lago on the upper slopes of mount etna in summer 2001 we describe the events leading to the formation of a small graben the formation of pit craters on the base of the graben the onset of phreatomagmatic activity a transition to intense strombolian activity and a return to phreatomagmatic activity as the eruption came to an end we discuss the reasons for these transitions and describe the morphological development of the cone during these events arcuate cracks on the southern part of the cone were related to withdrawal of magma at the end of the eruption other slope instabilities that developed during the eruption include the formation of small radial grain flows on the outer flanks of the cone and the collapse into the crater of part of the crater rim some of the failure planes we observed were first identified using a flir tm 695 thermal infrared camera this is the first time that infrared thermography has been used to detect instability of volcanic structures results obtained during this test case demonstrate that thermal cameras are a very useful tool for studies of volcanic instability

coupled textural and compositional characterization of basaltic scoria insights into the transition from strombolian to fire fountain activity at mount etna italy strombolian and fire fountain activities represent a common expression of explosive basaltic eruptions however the transition between these two eruptive styles and their source mechanisms are still debated we use textural and compositional studies to characterize pyroclastic material from both the strombolian and hawaiian style fire fountain phases of the january june 2000 etna activity we find that basaltic scoria presents distinctive textural and compositional features that reflect different modes of magma vesiculation and crystallization in the two eruptive regimes overall magma that forms strombolian scoria is far more crystallized less vesicular and more evolved indicating strong volatile depletion and longer residence time before being erupted fire fountain scoria indicates a fast rising magma with evidence of moderate syneruptive volatile exsolution the new textural and compositional data set is integrated with previous volcanological and geophysical investigations to provide further insights into the dynamics of fire fountains and to frame the transition from strombolian explosions to fire fountain activity into a model that may apply to future eruptions at mount etna as well as other active basaltic volcanoes

precambrian u pb zircon ages in eclogites and garnet pyroxenites from south brittany france an old oceanic crust in the west european hercynian belt abstract u pb zircon ages have been determined for two eclogites from the vendee and for two garnet pyroxenites from the baie d audierne in an episodic pb loss model the two discordia would give upper intercept ages around 1300 1250 ma and lower intercepts ages of 436 384 ma two interpretations are proposed 1 the 1250 1300 ma ages may reflect an unspecified upper mantle event or process the paleozoic ages correspond to the tectonic emplacement of an eclogitic mantle fragment into the continental crust 2 the protolith may have been extracted from the upper mantle 1250 1300 ma ago and stored in a crustal environment until it was metamorphosed under high pressure conditions around 400 ma ago this latter model is favoured by available geologic and isotopic data consequently we propose that a 1300 ma old oceanic crust was tectonicly incorporated into a sialic basement during the proterozoic this mixture was subsequently subducted during the paleozoic

observation of so2 degassing at stromboli volcano using a hyperspectral thermal infrared imager abstract thermal infrared tir imaging is a common tool for the monitoring of volcanic activity broadband cameras with increasing sampling frequency give great insight into the physical processes taking place during effusive and explosive event while fourier transform infrared ftir methods provide high resolution spectral information used to assess the composition of volcanic gases but are often limited to a single point of interest continuing developments in detector technology have given rise to a new class of hyperspectral imagers combining the advantages of both approaches in this work we present the results of our observations of volcanic activity at stromboli volcano with a ground based imager the telops hyper cam lw when used to detect emissions of sulfur dioxide so2 produced at the vent with data acquired at stromboli volcano italy in early october of 2015 we have developed an innovative technique based on a curve fitting algorithm to quickly extract spectral information from high resolution datasets allowing fast and reliable identification of so2 we show in particular that weak so2 emissions such as inter eruptive gas puffing can be easily detected using this technology even with poor weather conditions during acquisition e g high relative humidity presence of fog and or ash then artificially reducing the spectral resolution of the instrument we recreated a variety of commonly used multispectral configurations to examine the efficiency of four qualitative so2 indicators based on simple brightness temperature difference btd our results show that quickly changing conditions at the vent including but not limited to the presence of summit fog render the establishment of meaningful thresholds for btd indicators difficult building on those results we propose recommendations on the use of multispectral imaging for so2 monitoring and routine measurements from ground based instruments

accretion rate of cosmic spherules measured at the south pole micrometeorites are terrestrially collected extraterrestrial particles smaller than about 1 mm which account for most of the mass being accreted to the earth1 2 compared with meteorites micrometeorites more completely represent the earth crossing meteoroid complex3 4 and should include fragments of asteroids comets mars and our moon as well as pre solar and interstellar grains3 6 previous measurements of the flux of micrometeoroids that survive to the earth s surface have large uncertainties owing to the destruction of particles by weathering7 8 9 inefficiencies in magnetic collection or separation techniques7 8 9 low particle counts10 11 poor age constraint7 8 9 12 13 or highly variable concentrating processes12 13 here we describe an attempt to circumvent these problems through the collection of thousands of well preserved and dated micrometeorites from the bottom of the south pole water well which supplies drinking water for the scott amundsen station using this collection we have determined precise estimates of the flux and mass distribution for 50 700 m cosmic spherules melted micrometeorites allowing for the expected abundance of unmelted micrometeorites14 in the samples our results indicate that about 90 of the incoming mass of submillimetre particles evaporates during atmospheric entry our data indicate the loss of glass rich and small stony spherules from deep sea deposits7 8 and they provide constraints for models describing the survival probability of micrometeoroids15 16

spectroscopic evidence for a lava fountain driven by previously accumulated magmatic gas the eruption of mount etna in 2000 was notable for an exceptional series of 64 periodic lava fountains propelling lava fragments to heights of up to 900 metres it has been difficult to determine which of two suggested sources of power gas release from the magma itself during its rapid ascent or a build up of pressure from gas accumulated at depth is the driving force for these dramatic jets but one of the etna fountains provided volcanologists with the opportunity to use remote sensing not that remote see picture on the following page to determine the infrared spectra of the gas phase this revealed the chemical composition of the gas that powered this fountain as consistent with an origin in an accumulated gas layer lava fountains are spectacular continuous gas jets propelling lava fragments to heights of several hundred metres which occasionally occur during eruptions of low viscosity magmas1 2 3 4 5 whether they are generated by the effervescent disruption of fast rising bubbly melt2 3 4 5 or by the separate ascent of a bubble foam layer accumulated at depth6 7 still remains a matter of debate8 no field measurement has yet allowed firm discrimination between these two models a key insight into the origin of lava fountains may be gained by measuring the chemical composition of the driving gas phase this composition should differ markedly depending on whether the magma degassing occurs before or during eruption9 10 here we report the analysis of magmatic gas during a powerful 250 600 m high lava fountain measured with fourier transform infrared spectroscopy11 12 13 14 on mount etna sicily the abundances of volcanic gas species determined from absorption spectra of lava radiation reveal a fountain gas having higher co2 s and s cl ratios than other etnean emissions14 15 16 17 18 and which cannot derive from syn eruptive bulk degassing of etna basalt19 20 instead its composition suggests violent emptying of a gas bubble layer previously accumulated at about 1 5 km depth below the erupting crater

applications of quantitative thermal infrared hyperspectral imaging 8 14 μm measuring volcanic so 2 mass flux and determining plume transport velocity using a single sensor remote measurements of sulfur dioxide so2 path concentration and emission rate mass flux released by passive volcanic degassing are a key diagnostic of volcanic behavior so2 gas concentrations are also important for public health despite the significance of measuring so2 mass flux at active volcanoes an accurate method is still very difficult to obtain due largely to uncertainties of plume transport velocities and radiative transfer calculations here we present a new infrared imaging method for deriving so2 flux at active volcanoes with less than 20 plume transport velocity and radiative transfer uncertainties the thermal hyperspectral imager thi was used for this study thi is an uncooled remote sensing long wave thermal infrared tir imaging hyperspectral sensor that can obtain 50 wavelength samples between 8 and 14 m measurements of so2 at the summit of k lauea volcano collected using thi are presented where we obtained for the periods of july 24 26 2017 and february 5 6 2018 a so2 flux raging between 0 and 20 kg s with occasional peaks higher than 40 kg s the spatial distribution of so2 path concentrations was obtained from the thi images by processing them using a newly developed so2 retrieval algorithm the so2 amenable lookup table algorithm so2 alta the sampling rate 30 hz of the microbolometer camera within thi means raw frames can be used for wind velocity derivation volcanic plume motion can be thus inferred by tracking plume features in sequential frames using spatial correlation techniques and knowing the camera angular orientation volcanic so2 flux was estimated from the spatial distribution of so2 and wind velocity we evaluated temporal trends of the so2 flux during the day and the night at the summit of k lauea volcano under both clear sky weather with northeasterly trade winds and cloudy sky conditions with low variable wind these tests showed that the camera and techniques described in this paper provide an effective tool for monitoring so2 fluxes remotely with less than 20 plume transport velocity and radiative transfer uncertainties and under a variety of background conditions clear and cloudy sky cold and hot backgrounds

a co2 rich gas trigger of explosive paroxysms at stromboli basaltic volcano italy in addition to rhythmic slug driven strombolian activity stromboli volcano occasionally produces discrete explosive paroxysms 2 per year on average for the most frequent ones that constitute a major hazard and whose origin remains poorly elucidated partial extrusion of the volatile rich feeding basalt as aphyric pumice during these events has led to consider their triggering by the fast ascent of primitive magma blobs from possibly great depth here i examine and discuss the alternative hypothesis that most of the paroxysms could be triggered and driven by the fast upraise of co2 rich gas pockets generated by bubble foam growth and collapse in the sub volcano plumbing system data for the so2 and co2 crater plume emissions are used to show that stromboli s feeding magma may originally contain as much as 2 wt of carbon dioxide and early coexists with an abundant co2 rich gas phase with high co2 so2 molar ratio 60 at 10 km depth below the vents compared to 7 in time averaged crater emissions pressure related modelling indicates that the time averaged crater gas composition and output are well accounted for by closed system decompression of the basalt gas mixture until the volcano crust interface 3 km depth followed by open degassing and crystallization in the volcano conduits however both the low viscosity and high vesicularity of the basaltic magma permit bubble segregation and bubble foam growth at deep sill like feeder discontinuities and at shallower physical boundaries such as the volcano crust interface where the gas rich aphyric basalt interacts with the unerupted crystal rich and viscous magma drained back from the volcano conduits gas pressure build up and bubble foam collapse at these boundaries will intermittently trigger the sudden upraise of co2 rich gas blobs that constitute the main driving force of the paroxysms deeper sourced gas blobs driving the most powerful explosions will be the richest in co2 and have highest co2 so2 ratios this mechanism is shown to account well for the dynamic seismic and petrologic features of stromboli s paroxysms and hence to provide a potential alternative interpretation for their genesis and their forecasting enhanced bubble foam leakage prior to a paroxysm or foam emptying in several steps should lead indeed to precursory upstream of co2 rich gas and increasing co2 so2 ratio in crater plume emissions the recent detection of such signals prior to two explosions in december 2006 and march 2007 strongly supports this expectation and the model proposed in this study

mineralogy of tagish lake an ungrouped type 2 carbonaceous chondrite in this paper we describe the recovery handling and preliminary mineralogical investigation of the tagish lake meteorite tagish lake is a type 2 carbonaceous chondrite which bears similarities to ci1 and cm chondrite groups but is distinct from both abundant phyllosilicates as well as chondrules however sparse and common olivine grains in the matrix preclude any other classification the bulk density of tagish lake 1 67 g cc which is far lower than ci or cm chondrites 2 2 2 3 and 2 6 2 9 g cc respectively or any other meteorite for that matter we have identified two lithologies a dominant carbonate poor lithology and a less abundant carbonate rich lithology the meteorite is a breccia at all scales we have noted similarities between tagish lake and some clasts within the enigmatic meteorite kaidun possibly there are genetic relationships here worth exploring in the paper we describe a clast of cm1 material within tagish lake which is very similar to a major lithology in kaidun

igneous rims on micrometeorites abstract melting of micrometeorites mms due to atmospheric entry heating causes significant changes in the textures mineralogies and compositions of particles that obscure their primary properties and greatly complicate interpretation of these extraterrestrial materials despite the abundance of melted mms the nature of melting processes in these materials is poorly constrained in this study mineralogical textural and compositional data on 77 mms with igneous rims are presented which suggest that fusion of micrometeorites during atmospheric entry occurs initially by surface melting textural and mineralogical evidence are presented that demonstrate unequivocally that igneous rims crystallized from a melt surrounding a largely unmelted core and establish melting as a gradational process the compositions of igneous rims on fine grained mms fgmms are broadly similar to those of the unmelted core except for depletions in volatile and moderately volatile elements produced by partial evaporation and suggest the formation of the rims by melting of the fine grained matrix core enrichments in fe si ni si and mn si in igneous rims compared with unmelted cores within fgmms are suggested to occur due to the migration of fe s eutectic liquids from the core of the particle into the surface melt layer the sulphide liquids are probably generated in the core of the particle under reducing conditions resulting by the pyrolysis of carbonaceous materials the presence of igneous rims on fgmms is enabled by the thermal decomposition of phyllosilicates and therefore indicates that fgmms were hydrated particles prior to atmospheric entry in contrast the compositions of igneous rims on coarse grained mms cgmms are difficult to reconcile with those of the unmelted core and instead closely resemble those of fgmms the igneous rims of cgmms are therefore suggested to form by melting of fine grained matrix that was present on the exterior of these particles prior to atmospheric entry coarse grained mms with igneous rims thus were originally composite micrometeoroids which consist of both fine grained and coarse grained materials and are thought to be samples of chondrule like objects the abundance of composite mms to cgmms allows a first estimate of the mean chondrule radius within the parent bodies of mms of 625 m to be made

les eaux thermales des granites de galice espagne des eaux carbogazeuses aux eaux alcalines thermal waters from granites of galicia spain from co2 rich to high ph waters abstract thermal waters from galicia spain range from co 2 rich low ph to high ph sulfide rich waters going through intermediate waters in order to explain the variations of their chemical composition we present a discussion of the major factors governing the water composition we eiscuss especially the isochemical recrystallization of a granite it is shown that the equilibrium mineral association of the water alkali granite system is unique for chalco alkaline granites two different associations are possible depending on the chemical composition of the granite the effect of an addition of co 2 is also discussed some criteria allowing a distinction between fully equilibrated and non equilibrated waters are presented finally the composition of galician waters is explained by different initial co 2 contents and by different values of the degree of the granite water reaction progress

pulsed lava effusion at mount etna during 2001 effusion rate and degassing data collected at mt etna volcano italy in 2001 show variations occurring on time scales of hours to months we use both long and short term data sets spanning january to august to identify this variation the long data sets comprise a satellite and ground based time series of effusion rates and the latter include field based effusion rate and degassing data collected may 29 31 the satellite derived effusion rates for january through august reveal four volumetric pulses that are characterized by increasing mean effusion rate values and lead up to the 2001 flank eruption peak effusion rates during these 23 57 day pulses were 1 2 m 3 s 1 in pulse 1 1 jan 4 mar 1 1 m 3 s 1 in pulse 2 5 mar 21 apr 4 2 m 3 s 1 in pulse 3 24 apr 18 jun 8 8 m 3 s 1 in pulse 4 23 jun 16 jul and 22 2 m 3 s 1 during the flank eruption 17 jul 9 aug rank order analysis of the satellite data shows that effusion rate values during the 2001 flank eruption define a statistically different trend than etna s persistent activity from jan 1 to jul 17 data prior to the flank eruption obey a power law relationship that may define an effusion rate threshold of f3 5 m 3 s 1 for etna s typical persistent activity our short term data coincide with the satellite derived peak effusion period of pulse 3 degassing at vent puff frequency shows a general increase from may 29 to 31 with hour long variations in both puff frequency and lava flow velocity effusion rate we identify five 3 14 h degassing periods that contain 26 shorter 19 126 min long oscillations this variation shows some positive correlation with effusion rate measurements during the same time period if a relationship between puff frequency and effusion rate is valid we propose that their short term variation is the result of changes in the supply rate of magma to the near vent conduit system therefore these short term data provide some evidence that the clear weeks to months long variation in etna s effusive activity january august 2001 was overprinted by a minutes to hour scale oscillation in shallow supply d 2004 elsevier b v all rights reserved

rare earth element distribution in some hercynian granitoids from the finisterre region nw spain two series of granitoids are present in the finisterre region one is formed mainly by syn collision two mica leucogranites the other is composed of syn and post collision granodiorites and monzogranites of calc alkaline affinity the emplacement of these granitoids took place during and after the main phases of regional deformation petrographic and geochemical studies on the leucogranites suggests a common crustal origin with the surrounding metamorphic series which includes metasediments and orthogneisses of medium to high grade amphibolite facies the syn and post collision calc alkaline series is associated with basic to intermediate rocks suggesting a lower crustal origin ree data have been used to characterize the two types of granitoids and to model the source areas of generation there is no evidence for an origin of the granitoids by melting of mantle type igneous rocks instead the sequences of granitoids can be explained assuming different degrees of partial melting from a heterogeneo

challenges associated with the atmospheric monitoring of areal emission sources and the need for optical remote sensing techniques an open path fourier transform infrared op ftir spectroscopy experience report in recent years op ftir spectrometry has been successfully used to monitor hazardous air pollutants greenhouse gases and other emission products this ground based remote sensing method has proven itself to be a flexible long path technique for the characterization of large atmospheric volumes enabling simultaneous detection of various volatile atmospheric compounds relevant for environmental assessment via a single rapid measurement within our research we applied both active and passive ground based op ftir spectroscopy as a screening tool for the detection of fugitive greenhouse gas emissions the method was proven as offering a suitable compliance toolbox for continuous monitoring of the complex systems at the ground surface atmosphere boundary allowing large scale identification and quantification of atmospheric composition over large areas to be achieved in terms of identifying zones of higher leakage vulnerability in this paper we compiled our research results and highlight the adaption options of the field technology illustrated measuring options and case studies at urban natural and industrial sites furthermore this technology was validated regarding its applicability in environmental atmospheric monitoring the results show that passive op ftir measurements offer the chance to achieve robust and reliable surveys in various arbitrary measurement directions to gain a comprehensive overview however to improve quantitative analysis in the case of weak sources the application of an active open path spectrometer is recommended it should be noted that our investigations demonstrate that site specific parameters such as prevailing wind directions meteorological conditions topographic influences infrastructure other artificial emission sources and biological background need to be measured both prior to and during atmospheric monitoring and should be taken into account for comprehensive interpretation

sr z sbnd nd isotopic record of multi stage interactions between mantle derived magmas and crustal components in a collision context the ultramafic granitoid association from vivero hercynian belt nw spain late stage epizonal calc alkaline granitoids of the hercynian belt are often associated with coeval more basic rocks such granitoids have been the focus of special attention when studying the role of mantle derived magmas in granitoid genesis these studies conclude that basic magmas are involved in granitoid production but their contribution to the chemical composition of granitoids is often controversial the vivero massif nw spain includes calc alkaline granitoids and coeval ultramafic and mafic rocks but these granitoids are syntectonic and intruded into middle crustal levels during an early stage scattered major and trace element chemistry together with heterogeneous sr nd isotopic results preclude an origin of this ultramafic to granitoid association by any closed system fractionation process ultramafic rocks include peridotites pyroxenites and homblendites with endi from 3 5 to 1 3 and 87sr86sr i ratio from 0 7059 to 0 7080 they are interpreted as cumulates formed by in situ fractional crystallization from contaminated basaltic magmas particularly by interaction with 87sr enriched fluids mafic rocks comprise biotite amphibole diorites quartz diorites and tonalites with ndi from 3 8 to 0 0 and 87sr86sr i ratio from 0 7058 to 0 7073 they represent either cumulates or more evolved magmas of calc alkaline affinity these rocks display an inverse correlation between the degree of differentiation and the degree of contamination inferred from isotope data this points to wall rock assimilation by thermal erosion during ascent of basic magmas up to the middle crust and supports the participation of mantle sources with positive end and 87sr86sr i 0 7058 granitoids range from amphibole biotite tonalites through biotite granodiorites to monzonitic granites they show an isotopic trend which diverges from that of ultramafic and mafic rocks endi 6 0 to 1 9 decreases while 87sr86sr i ratio 0 7061 to 0 7082 increases from tonalites to monzonitic granites reflecting an increasing contribution of crustal components in more differentiated rocks assimilation and fractional crystallization mixing included account for such an evolution contamination of basic magmas by this process occurring at deeper crustal level produced hybrid tonalites and related mafic magmatic enclaves only monzonitic granites are interpreted as pure crustal melts their hree fractionated patterns gd yb 4 5 suggest equilibrium with a garnet rich residuum partial melting of moderate time integrated rb sr protolith such as greywackes and or meta igneous rocks of intermediate acid composition could account for the isotopic composition of these monozogranites this example shows that at least some calc alkaline granitoids of collisional setting are not produced by pure intra crustal melting they are formed through a complex multi stage hybridization process involving mantle derived magmas crustal components and several concomitant magmatic processes

remote detection of hcl and so2 in volcanic gas from unzen volcano japan a telescope attached ft ir spectral radiometer was applied for remote measurement of chemical composition of the volcanic gas of unzen volcano japan which started erupting in november 1990 the observations were carried out at the site about 1 3 km away from the gas emitting region of the volcano in march and july 1992 absorption features of so2 vl and hcl were identified and column amounts of so2 and hcl of the volcanic gas plume were estimated using a nonlinear least squares method the so2 hcl ratio was in the range between 0 7 and 1 8 for both march and july observations this is the first remote ground based observation of hcl in volcanic gas

generation and emplacement of shear related highly mobile crustal melts the synkinematic leucogranites from the variscan tormes dome western spain the tormes dome consists of s type granites that intruded into ordovician augen gneisses and neoproterozoic lower cambrian metapelites metagreywackes at different extents of migmatization s type granites are mainly equigranular two mica granites occurring as 1 enclave laden subvertical feeder dykes 2 small external sill like bodies with size and shape relations indicative for self similar pluton growth and 3 as large pluton bodies emplaced at higher levels than the external ones these magmas were highly mobile as it is inferred from the high contents of fluxing components the disintegration and alignment of pelitic xenoliths in feeder dykes and at the bottom of some sill like bodies field relations relate this 311 ma magmatism u pb monazite to the regional shearing of the d3 variscan event partial melting modeling and the relatively high estimated liquidus temperatures indicate biotite dehydration partial melting 800 840 c and 400 650 mpa rather than water fluxed melting implying that there was no partial melting triggered by externally derived fluids in the shear zones instead the subvertical shear zones favored extraction of melts that formed during the regional migmatization event around 320 ma nd isotope variation among the granites might reflect disequilibrium partial melting or different protoliths mass balance and trace element partial melting modeling strongly suggest two kinds of fertile crustal protoliths augen gneisses and metapelites slight compositional variation among the leucogranites does not reflect different extent of protolith melting but is related to a small amount of fractional crystallization 13 for the equigranular granites which is generally more pronounced in shallower batholitic leucogranites than in the small and homogeneous sill like bodies the lower extent of fractional crystallization and the higher pressure emplacement conditions of the sill like bodies support a more restricted movement through the crust than for batholitic leucogranites

validating the accuracy of so 2 gas retrievals in the thermal infrared 8 14 μm quantifying sulfur dioxide so2 in volcanic plumes is important for eruption predictions and public health ground based remote sensing of spectral radiance of plumes contains information on the path concentration of so2 however reliable inversion algorithms are needed to convert plume spectral radiance measurements into so2 path concentrations various techniques have been used for this purpose recent approaches have employed thermal infrared tir imaging between 8 m and 14 m to provide two dimensional mapping of plume so2 path concentration using what might be described as dual view techniques in this case the radiance or its surrogate brightness temperature is computed for portions of the image that correspond to the plume and compared with spectral radiance obtained for adjacent regions of the image that do not i e clear sky in this way the contribution that the plume makes to the measured radiance can be isolated from the background atmospheric contribution this residual signal being converted to an estimate of gas path concentration via radiative transfer modeling these dual view approaches suffer from several issues mainly the assumption of clear sky background conditions at this time the various inversion algorithms remain poorly validated this paper makes two contributions firstly it validates the aforementioned dual view approaches using hyperspectral tir imaging data secondly it introduces a new method to derive so2 path concentrations which allows for single point so2 path concentration retrievals suitable for hyperspectral imaging with clear or cloudy background conditions the so2 amenable lookup table algorithm so2 alta uses the modtran5 radiative transfer model to compute radiance for a variety millions of plume and atmospheric conditions rather than searching this lookup table to find the best fit for each measured spectrum the lookup table was used to train a partial least square regression plsr model the coefficients of this model are used to invert measured radiance spectra to path concentration on a pixel by pixel basis in order to validate the algorithms tir hyperspectral measurements were carried out by measuring sky radiance when looking through gas cells filled with known amounts of so2 so2 alta was also tested on retrieving so2 path concentrations from the k lauea volcano hawai i for cloud free conditions all three techniques worked well in cases where background clouds were present then only so2 alta was found to provide good results but only under low atmospheric water vapor column amounts

the unusual 28 december 2014 dike fed paroxysm at mount etna timing and mechanism from a multidisciplinary perspective between 2011 and 2013 there were 43 lava fountain episodes from mount etna s new south east summit crater nsec in 2014 this intense activity was supplanted by sporadic strombolian explosions and the opening of an eruptive fissure between july and august the only lava fountaining episode of the year occurred on 28 december this was characterized by the emplacement of a shallow dike that at the surface fed two distinct lava flows from an ene wsw trending eruptive fissure here we provide a detailed picture of the onset of the dike emplacement as well as the mechanism driving its migration using a multidisciplinary data set based on seismic geodetic geochemical and volcanological observations the dike emplacement was preceded by a pressurization of the magmatic plumbing system recorded from august 2014 on this pressurization has been modeled as a vertically elongated magmatic source located beneath the summit craters at 4 5 km below sea level from september to october magma rising was also detected by seismic and geochemical data that highlighted pressurization of the shallower portion of the plumbing system we suggest that the 28 december 2014 dike emplacement resulted from a modification of the preexisting nsec shallow plumbing system largely due to drainage of the main shallow conduit during the july august 2014 eruptive fissure activity such a structural modification might have created the conditions for magma emplacement as a dike like structure

extensional flow produces recumbent folds in syn orogenic granitoids padron migmatitic dome nw iberian massif this contribution provides a case example on the generation of large scale recumbent folds in syn orogenic granitoids we analyze the progressive reworking of extension related structures into later ones after a period of crustal thickening the padron migmatitic dome formed after the climax of the gondwana laurussia collision in the late paleozoic petrostructural analysis carried out in the eastern flank of this dome reveals that extensional flow resulted in progressive exhumation of mainland gondwana which rested under peri gondwanan allochthonous terranes and a suture zone during maximum crustal thickening exhumation proceeded up to upper crust levels andalusite stability field along with partial melting of the middle lower crust and with the generation of granitoid laccoliths during an early extensional stage newly formed lithological and mechanical anisotropies such as the presence of variably sized sheet shaped bodies of syn orogenic granitoids provided a favorable rheological setting for fold nucleation during the intermediate stages of extension in extending orogenic crust whether recumbent folds occur after significant melt production depends on the lateral vertical flow ratio and on the orientation of deforming bodies with regard to kinematic strain axes we suggest that subhorizontal extensional flow dominated over vertical flow during the early and intermediate stages of the evolution of the padron dome a component of vertical diapiric flow caused progressive tilting of the sheet like bodies and obliquity respect to strain axes this resulted in the development of regional scale folds at the expense of syn orogenic granitoids such as in the case of the portomouro recumbent synform extensional ductile flow was oblique to the trend of the orogen during the whole process and directed to the nnw during the formation of recumbent folds non coaxial shearing favored an nnw sse elongate shape for the syn kinematic granitic massifs as well as the subsequent nucleation of recumbent folds deformation concentrated along discrete detachments during the late stages of extension

lead isotopic composition of hercynian granitic k feldspars constrains continental genesis lead isotope compositions have been determined in many k feldspars from granitic rocks emplaced during the variscan hercynian orogeny sensu lato around 300 myr in various parts of europe and the eastern us the ratios show a regular geographical pattern with contours arched around southern france and parallel to the atlantic coast of the us this distribution parallels predriftpalaeogeographical zones during the palaeozoic the lead isotope pattern of variscan granitic rocks is similar to that of some orogenic volcanic suites but is better explained by crustal melting than by an hercynian mantle crust material mixing the continental crust from these areas must be older than 3 000 myr large scale fluid circulation in the crust during orogenic processes apparently explains the observed geographical patterns of lead isotopes

ftir remote sensing of fractional magma degassing at mount etna sicily abstract the chemical composition of volcanic gas emissions from each of the four summit craters of mount etna was measured remotely in may 2001 using a fourier transform infrared ftir spectrometer operated on the upper flanks of the volcano the results reveal constant hci hf ratio but distinct so2 hc1 and so2 hf ratios in the emitted gases which in the light of melt inclusion data for etna basalts can be interpreted in terms of escape of gases from partially and variably degassed magma at different depths beneath the summit gases released from the three main summit craters bocca nuova voragine and northeast had an identical composition controlled by bulk degassing of a single magma body that had previously lost c 25 0 of its original sulphur the similar gas composition at all three main craters suggests that these are connected to a central conduit system that branches at relatively shallow depth measurements of the bulk volcanic plume on the same day c 7 km downwind show that degassing from these craters dominated the total gas output of the volcano and that no significant chemical evolution occurred within the plume over a time scale of c 12 min weaker gas emissions from the southeast crater were comparatively depleted in so2 so2 hc1 and so2 hf ratios a factor of two lower implying that this crater is fed either by a separate conduit or by a branch of the central conduit whose geometry favours solubility controlled volatile fractionation still lower so2 hc1 and so2 hf ratios measured for residual degassing of a lava flow erupted from the southeast crater verify the lower solubility and earlier escape of sulphur compared to halogens at etna fractional magma degassing is also implied by strong chemical contrasts between the bulk volcanic plume and fissure gas emissions measured during the july august 2001 flank eruption these results highlight the ability of ftir spectrometry to detect fine spatial and temporal variations in magma degassing processes and thereby constrain models of shallow plumbing systems introduction magmas contain dissolved volatiles h20 co2 s c1 f etc with differing solubility behaviom which gradually reach a saturation pressure and exsolve into a separate gas phase bubbles during magma ascent and crystallization this volatile phase plays a central role in magmatic and volcanic processes e g anderson 1975 and its chemical composition changes from depth to the surface according to the pressure controlled solubility behaviour of each volatile species but also as a function of the dynamics of magma supply and ascent sparks 2003 this volume in fact gas bubbles may rise with either the same velocity as surrounding magma allowing continuous gas melt equilibration and single step bulk gas emission at the surface or with a higher velocity thereby reaching the surface independently of the parental magma batch e g sparks 1978 vergniolle jaupart 1986 in the latter case chemical equilibrium between gas and magma may be inhibited sustained high gas fluxes in excess of lava production on basaltic volcanoes such as etna and stromboli typically require a separated bubble flow and in the long term convective renewal of volatile rich magma from depth francis

melt inclusion record of the conditions of ascent degassing and extrusion of volatile rich alkali basalt during the powerful 2002 flank eruption of mount etna italy 1 two unusual highly explosive flank eruptions succeeded on mount etna in july august 2001 and in october 2002 to january 2003 raising the possibility of changing magmatic conditions here we decipher the origin and mechanisms of the second eruption from the composition and volatile h2o co2 s cl content of olivine hosted melt inclusions in explosive products from its south flank vents our results demonstrate that powerful lava fountains and ash columns at the eruption onset were sustained by closed system ascent of a batch of primitive volatile rich 4 wt basaltic magma that rose from 10 km depth below sea level bsl and suddenly extruded through 2001 fractures maintained opened by eastward flank spreading this magma the most primitive for 240 years probably represents the alkali rich parental end member responsible for etna lavas evolution since the early 1970s few of it was directly extruded at the eruption onset but its input likely pressurized the shallow plumbing system several weeks before the eruption this latter was subsequently fed by the extrusion and degassing of larger amounts of the same but slightly more evolved magma that were ponding at 6 4 km bsl in agreement with seismic data and with the lack of preeruptive so2 accumulation above the initial depth of sulphur exsolution 3 km bsl we find that while ponding this magma was flushed and dehydrated by a co2 rich gas phase of deeper derivation a process that may commonly affect the plumbing system of etna and other alkali basaltic volcanoes

the april 2007 eruption and the dolomieu crater collapse two major events at piton de la fournaise la reunion island indian ocean abstract after 10 years of high activity and 24 eruptions piton de la fournaise pdf produced on april 2 to may 1 2007 one of its most voluminous and intense eruption since at least one century the eruption focused at 590 m elevation in the grand brule on the south east flank of piton de la fournaise 7 km away from summit it was located close to the southern cliff of the grand brule volcano tectonic collapse the rempart du tremblet and to the nearby village called le tremblet and it highly rattled and incommoded the inhabitants there eleven hours after the beginning of the eruption the lava flows reached the sea and created 0 45 km 2 of new land until the end of eruption in the night of april 5 the rock column beneath dolomieu crater started to collapse with a piston like mechanism into the magma chamber forming within less than 24 h the most recent and well documented caldera we report in this paper the chronology of these two related major events in the recent activity of pdf seen by the scientific networks of the volcanological observatory ovpf ipgp and field observations which allowed to back up the scenario of the caldera formation and to quantify these two exceptional episodes

episode 49 of the pu u o o kupaianaha eruption of kilauea volcano breakdown of a steady state eruptive era the pu u o o kupaianaha eruption 1983 present is the longest lived rift eruption of either kilauea or neighboring mauna loa in recorded history the initial fissure opening in january 1983 was followed by three years of episodic fire fountaining at the pu u o o vent on kilauea s east rift zone 19km from the summit episodes 4 47 these spectacular events gave way in july 1986 to five and a half years of nearcontinuous low level effusion from the kupaianaha vent 3km to the cast episode 48 a 49th episode began in november 1991 with the opening of a new fissure between pu u o o and kupaianaha this three week long outburst heralded an era of more erratic eruptive behavior characterized by the shut down of kupaianaha in february 1992 and subsequent intermittent eruption from vents on the west flank of pu u o o episodes 50 and 51 the events occurring over this period are due to progressive shrinkage of the rift zone reservoir beneath the eruption site and had limited impact on eruption temperatures and lava composition

manaslu leucogranite a collision signature of the himalaya a model for its genesis and emplacement the manaslu pluton is one of 10 leucogranites that formed in the overthrusted higher himalaya after the indo eurasian collision field and analytical data indicate that the underlying migmatites of the tibetan slab may be where the leucogranitic melts were generated the himalayan crustal thrusting of a hot slab over a rather cold volcano sedimentary pile le fort 1975a provides the necessary release of fluids these fluids cross the main central thrust mct induce the partial anatexis of the overheated tibetan slab and produce a leucogranitic magma the emplacement of the magma at first is located along the main disharmonic plane above the mct between the infrastructure and the superstructure there it generates a convective hydrothermal system extending very far laterally according to the stratification of permeabilities progressive emplacement of the granite proceeds as the convected fluids including the fluids released by the saturated magma dissolve the mainly calcareous host rocks of tibetan sedimentaries a frozen image of this caving out progression is given by the extensive network of granitic dikes outside the pluton the two quite independant fluid cycles of the generation and of the emplacement were triggered or guided by the tectonics due to collision this two fold model dominated by fluid activity may be of importance for other leucogranites and granites

first testing of a volcano doppler radar voldorad at mount etna italy a medium power 1 kw doppler radar of limited weight 110 kg and working in the uhf band has been developed for active remote sensing of volcanic eruptions named voldorad this radar is designed to monitor eruptive activities of variable magnitude at medium distance range 0 5 5 km in any weather condition and fills the gap between low and high power radar or sodar systems previously tested on volcanoes voldorad was operated for the first time during an eruption of mt etna on october 11 12 1998 doppler spectra recorded at 1 km distance from the vent reveal powerful echoes during the eruption paroxysm lava fountains which gradually decreased along with declining activity an average vertical velocity of 80 87 m s 1 is inferred for the eruptive jets

observations of volcanic tremor at mount st helens volcano digital recordings of ground motion during tremor episodes accompanying eruptions at mount st helens volcano in the state of washington on august 7 and october 16 18 1980 are studied the spectra of the vertical component waveforms contain at least two dominant peaks at 1 0 and 1 3 hz for all events recorded during both eruptions that were studied spectra of horizontal ground motion show peaks at 0 9 and 1 1 hz the relative amplitude of the two peaks changes between tremor episodes and during single tremor episodes and shows no consistent relation to amplitude of ground motion spectra of long period earthquakes are very similar to those of tremor events suggesting that tremor is composed of many long period earthquakes that occur over a period of time the unique waveform of tremor events observed at mount st helens must be due to a source effect since the relative amplitude of the two dominant peaks changes during tremor episodes the path effect on tremor waveforms is small since there are no peaks in the spectra of waveforms recorded during tectonic earthquakes occurring in the vicinity of mount st helens the consistency of the location of the spectral peaks for the wide range of tremor amplitudes means that there must be a physical length at the source that is constant independent of the amplitude of motion at the source variations in amplitude of motion generated during tremor events must be due to variations in the force driving the tremor amplitudes of ground motion varies between 0 11 and 4 7 m seismic moment rates during the two eruptions are calculated using the model of aki et al 1977 and found to vary between 6 1018 and 1 1020 dynes cm s 1 which are larger than values found by aki et al 1977 who studied amplitudes of shallow tremor events recorded during the october 1963 eruption of kilauea volcano in hawaii study of tremor amplitudes recorded at corvallis oregon leads to the conclusion that tremor accompanying the cataclysmic may 18 1980 eruption was at least one order of magnitude larger in amplitude than tremor during august and october

multiparametric study of the february april 2013 paroxysmal phase of mt etna new south east crater european fp7 med suv mediterranean supersite volcanoes grant number 308665 european research council european fp7 fp 2007 2013 erc grant number 279802 sigma sistema integrato di sensori in ambiente cloud per la gestione multirischio avanzata

carbonaceous micrometeorites from antarctica over 100 000 large interplanetary dust particles in the 50 500 micrometers size range have been recovered in clean conditions from approximately 600 tons of antarctic melt ice water as both unmelted and partially melted dehydrated micrometeorites and cosmic spherules flux measurements in both the greenland and antarctica ice sheets indicate that the micrometeorites deliver to the earth s surface approximately 2000x more extraterrestrial material than brought by meteorites mineralogical and chemical studies of antarctic micrometeorites indicate that they are only related to the relatively rare cm and cr carbonaceous chondrite groups being mostly chondritic carbonaceous objects composed of highly unequilibrated assemblages of anhydrous and hydrous minerals however there are also marked differences between these two families of solar system objects including higher c o ratios and a very marked depletion of chondrules in micrometeorite matter hence they are chondrites without chondrules thus the parent meteoroids of micrometeorites represent a dominant and new population of solar system objects probably formed in the outer solar system and delivered to the inner solar system by the most appropriate vehicles comets one of the major purposes of this paper is to discuss applications of micrometeorite studies that have been previously presented to exobiologists but deal with the synthesis of prebiotic molecules on the early earth and more recently with the early history of the solar system

dynamics of degassing at kilauea volcano hawaii at kilauea volcano hawaii the recent long lived eruptions of mauna ulu and pu u o o have occurred in two major stages defining a characteristic eruptive pattern the first stage consists of cyclic changes of activity between episodes of fire fountaining and periods of quiescence or effusion of vesicular lava the second stage consists only of continuous effusion of lava we suggest that these features reflect the dynamics of magma degassing in a chamber which empties into a narrow conduit in the volcano chamber gas bubbles rise through magma and accumulate at the roof in a foam layer the foam flows toward the conduit and its shape is determined by a dynamic balance between the input of bubbles from below and the output into the conduit the foam thickness is proportional to lq e2 l g 1 4 where l and l are the viscosity and density of magma e is the gas volume fraction in the foam g is the acceleration of gravity and q is the gas flux the bubbles in the foam deform under the action of buoyancy and the maximum permissible foam thickness is hc 2 e lgr where is the coefficient of surface tension and r is the original bubble radius if this critical thickness is reached the foam collapses into a large gas pocket which erupts into the conduit foam accumulation then resumes and a new cycle begins the attainment of the foam collapse threshold requires a gas flux in excess of a critical value which depends on viscosity surface tension and bubble size hence two different eruption regimes are predicted 1 alternating regimes of foam buildup and collapse leading to the periodic eruption of large gas volumes and 2 steady foam flow at the roof leading to continuous bubbly flow in the conduit the essential result is that the continuous process of degassing can lead to discontinuous eruptive behavior data on eruption rates and repose times between fountaining phases from the 1969 mauna uiu and the 1983 1986 pu u o o eruptions yield constraints on three key variables the area of the chamber roof must be a few tens of square kilometers with a minimum value of about 8 km2 magma reservoirs of similar dimensions are imaged by seismic attenuation tomography below the east rift zone close to the roof the gas volume fraction is a few percent and the gas bubbles have diameters lying between 0 1 and 0 6 mm these estimates are close to the predictions of models for bubble nucleation and growth in basaltic melts as well as to the observations on deep submarine basalts the transition between cyclic and continuous activity occurs when the mass flux of gas becomes lower than a critical value of the order of 103 kg s in this model changes of eruptive regime reflect changes in the amount and size of bubbles which reach the chamber roof

chlorine partitioning between a basaltic melt and h2o co2 fluids at mount etna abstract partitioning experiments between a basaltic melt from mt etna and a low density hydrous fluid or vapor containing h 2 o or h 2 o co 2 were performed at 1200 1260 c at pressures between 1 and 200 mpa either near the nickel nickel oxide nno buffer or at two log units above it nno 2 and with different chloride concentrations most of the experiments were done at chloride brine undersaturated conditions although at the highest cl concentrations explored brine saturation might have been reached the average partition coefficients d cl fluid melt over the range of cl concentrations were derived on a weight basis by plotting the calculated concentrations of cl in the fluid phase versus the measured ones in the melt for h 2 o cl experiments in which the cl concentration in the melt was 0 4 wt a negative dependence between d cl f m and pressure is observed d cl fluid melt in h 2 o cl bearing experiments ranges between 11 14 at 1 and 25 mpa to 6 at 200 mpa at nno and between 4 at 50 mpa and 13 at 100 mpa at nno 2 addition of co 2 at nno yields lower partition coefficients than in co 2 free conditions over the pressure range investigated the negative pressure dependence observed for h 2 o cl experiments disappears when co 2 is present in the system overall once co 2 is introduced in the system cl fugacity in the silicate melt tends to increase thus resulting in a decrease of d cl f m application to mt etna shows that the composition of the volcanic plume in terms of cl records very shallow pressures of magma equilibration with its exsolved fluid

the fusion crusts of stony meteorites implications for the atmospheric reprocessing of extraterrestrial materials fusion crusts develop on all meteorites during their passage through the atmosphere but have been little studied we have characterized the textures and compositions of the fusion crusts of 73 stony meteorites to identify the nature of meteorite ablation spheres mas and constrain the processes operating during the entry heating most chondrite fusion crusts are porphyritic and are dominated by olivine glass and accessory magnetite whereas those of the achondrites are mainly glassy chondrite fusion crusts contain sulphide droplets with high ni contents 55 wt the partially melted substrate of ordinary chondrites underlying the outer melted crusts are dominated by silicate glass and composite metal sulphide and cr bearing fe oxide droplets that form as coexisting immiscible liquids enstatite chondrite substrates contain cr and mn bearing sulphides the substrates of the carbonaceous chondrites comprise a sulphide enriched layer of matrix the compositions of melted crusts are similar to those of the bulk meteorite however differences from whole rock suggest that three main processes control their chemical evolution 1 the loss and reaction of immiscible fe rich liquids 2 mixing between substrate partial melts and bulk melts of the melted crust and 3 the loss of volatile components by evaporation and degassing data from fusion crusts suggest that mas produced at low altitude have compositions within the range of those of silicate dominated cosmic spherules that are formed by the melting dust particles meteorite ablation spheres produced at high altitude probably have compositions very different from bulk meteorite and will resemble cosmic spherules derived from coarse grained precursors

characterization and initial field test of an 8 14 μm thermal infrared hyperspectral imager for measuring so 2 in volcanic plumes the ability to image and quantify so2 path concentrations in volcanic plumes either by day or by night is beneficial to volcanologists gas emission rates are affected by the chemical equilibria in rising magmas and a better understanding of this relationship would be useful for short term eruption prediction a newly developed remote sensing long wave thermal infrared ir imaging hyperspectral sensor the thermal hyperspectral imager thi was built and tested the system employs a sagnac interferometer and an uncooled microbolometer in rapid scanning configuration to collect hyperspectral images of volcanic plumes each pixel in the resulting image yields a spectrum with 50 samples between 8 and 14 m images are spectrally and radiometrically calibrated using an ir source with a narrow band filter and two blackbodies in this paper the sensitivity of the instrument for the purpose of quantifying so2 using well constrained laboratory experiments is evaluated and initial field results from k lauea volcano hawai i are presented the sensitivity of thi was determined using gas cells filled with known concentrations of so2 and using nist traceable blackbodies to simulate a range of realistic background conditions measurements made by thi were then benchmarked against a high spectral resolution off the shelf michelson ftir instrument theoretical thermal ir spectral radiances were computed with modtran5 for the same optical conditions to evaluate how well the known concentration of so2 in the gas cells could be retrieved from the resulting thi spectra finally thi was recently field tested at k lauea to evaluate its ability to image the concentration of so2 in a real volcanic plume a path concentration of 7150 ppm m was retrieved from measurements made near the halema uma u vent

the exceptional activity and growth of the southeast crater mount etna italy between 1996 and 2001 between 1971 and 2001 the southeast crater was the most productive of the four summit craters of mount etna with activity that can be compared on a global scale to the opening phases of the pu u k paianaha eruption of k lauea volcano hawai i the period of highest eruptive rate was between 1996 and 2001 when near continuous activity occurred in five phases these were characterized by a wide range of eruptive styles and intensities from quiet non explosive lava emission to brief violent lava fountaining episodes much of the cone growth occurred during these fountaining episodes totaling 105 events many showed complex dynamics such as different eruptive styles at multiple vents and resulted in the growth of minor edifices on the flanks of the southeast crater cone small pyroclastic flows were produced during some of the eruptive episodes when oblique tephra jets showered the steep flanks of the cone with hot bombs and scoriae fluctuations in the eruptive style and eruption rates were controlled by a complex interplay between changes in the conduit geometry including the growth of a shallow magma reservoir under the southeast crater magma supply rates and flank instability during this period volume calculations were made with the aid of gis and image analysis of video footage obtained by a monitoring telecamera between 1996 and 2001 the bulk volume of the cone increased by 36 106 m3 giving a total 1971 2001 volume of 72 106 m3 at the same time the cone gained 105 m in height reaching an elevation of about 3 300 m the total dre volume of the 1996 2001 products was 90 106m3 this mostly comprised lava flows 72 106 m3 erupted at the summit and onto the flanks of the cone these values indicate that the productivity of the southeast crater increased fourfold during 1996 2001 with respect to the previous 25 years coinciding with a general increase in the eruptive output rates and eruption intensity at etna this phase of intense summit activity has been followed since the summer of 2001 by a period of increased structural instability of the volcano marked by a series of important flank eruptions

degassing dynamics of basaltic lava lake at a top ranking volatile emitter ambrym volcano vanuatu arc persistent lava lakes are rare on earth and provide volcanologists with a remarkable opportunity to directly investigate magma dynamics and degassing at the open air ambrym volcano in vanuatu is one of the very few basaltic arc volcanoes displaying such an activity and voluminous gas emission but whose study has long remained hampered by challenging accessibility here we report the first high temporal resolution every 5 s measurements of vigorous lava lake degassing inside its 300 m deep benbow crater using op ftir spectroscopy our results reveal a highly dynamic degassing pattern involving i recurrent 100 200 s short period oscillations of the volcanic gas composition and temperature correlating with pulsated gas emission and sourced in the upper part of the lava lake ii a continuous long period 8 min modulation probably due to the influx of fresh magma at the bottom of the lake and iii discrete co2 spike events occurring in coincidence with the sequential bursting of meter sized bubbles which indicates the separate ascent of large gas bubbles or slugs in a feeder conduit with estimated diameter of 6 1 m this complex degassing pattern measured with unprecedented detail and involving both coupled and decoupled magma gas ascent over short time scales markedly differs from that of quieter lava lakes at erebus and kilauea it can be accounted for by a modest size of benbow lava lake and its very high basalt supply rate 20 m3 s 1 favouring its rapid overturn and renewal we verify a typical basaltic arc signature for ambrym volcanic gas and based on contemporaneous so2 flux measurements we evaluate huge emission rates of 160 gg d 1 of h2o 10 gg d 1 of co2 and 8 gg d 1 of total acid gas so2 hcl and hf during medium activity of the volcano in 2008 such rates make ambrym one of the three most powerful volcanic gas emitters at global scale whose atmospheric impact at local and regional scale may be considerable

2001 flank eruption of the alkali and volatile rich primitive basalt responsible for mount etna s evolution in the last three decades abstract since the early 1970s enhanced eruptive activity of mount etna has been accompanied by selective geochemical changes in erupted lavas among which a gradual increase of alkalis whose origin is still debated here we provide further insight into the origin of this recent evolution based on a detailed study of the chemistry and dissolved volatile content of melt inclusions trapped in olivine crystals of unusual plagioclase poor primitive basalt that was extruded during a highly explosive flank eruption in july august 2001 two types of lava were erupted simultaneously along a n s fracture system trachybasalts from the upper vents 2950 2700 m were simply drained out by fracturing of the central volcanic conduit they are identical to summit crater lavas and contain mg poor olivines fo 70 72 with evolved and volatile poor melt inclusions that represent late stage crystallisation during shallow open conduit degassing in contrast plagioclase poor basalt 80 of total extruded through the lower vents 2550 2100 m derived from lateral dyke intrusion of a more primitive and volatile rich magma across the sedimentary basement this primitive melt is best preserved in rare fo 82 4 80 5 skeletal olivines present in lapilli deposits from the most powerful activities at the 2550 m vent its high dissolved contents of h 2 o 3 4 wt co 2 0 11 to 0 41 wt s 0 32 wt cl 0 16 wt and f 0 094 wt point to its closed system ascent from 400 to 250 mpa 12 to 6 5 km depth b s l however the predominance of euhedral olivine phenocrysts with common reverse zoning cores fo 76 78 and rims fo 78 80 and decrepited inclusions shows that most of the erupted basalt derived from a slightly more evolved crystallizing body of the same magma that was invaded by the uprising primitive melt prior to erupting the few preserved inclusions in these olivines indicate pre eruptive storage of that magma body at about 5 km depth b s l in coherence with seismic data we propose that the 2001 flank eruption resulted from gradual overpressuring of etna s shallow plumbing system due to the influx of volatile rich primitive basalt that may have begun several months in advance we find that this basalt is much richer in alkalis 2 0 wt k 2 o and has higher s cl 2 0 but lower cl k and cl f ratios than all pre 1970s etnean lavas 1 4 wt k 2 o s cl 1 5 as further exemplified by melt inclusions in entrained olivine xenocrysts combining these new observations with previously published data we argue that the 2001 basalt represents a new alkali rich basic end member feeding mt etna only few amount of which had previously been extruded during a 1974 peripheral eruption and more recently during brief paroxysmal summit events over the last three decades this new magma has progressively mixed with and replaced the former k poorer trachybasalts filling the plumbing system leading to extrusion of gradually more primitive and alkali richer lavas its geochemical singularities cannot result from shallow crustal contaminations instead they suggest the involvement of an alkali richer but cl poorer arc type component during recent magma genesis beneath etna

determination of the rare earth element abundances in 29 international rock standards by instrumental neutron activation analysis a critical appraisal of calibration errors abstract a standard additions method has been used to calibrate an in house multi element rock standard for the analysis of the rare earth elements ree and th ta hf and co by instrumental neutron activation analysis this preliminary calibration with a precision of typically better than 7 1 has been refined by comparing our analyses of the four u s g s standard rocks agv 1 bcr 1 g 2 and gsp 1 with compiled analyses obtained by a critical survey of over 70 published references our standard calibration was adjusted by the average discrepancy between our analyses and published analyses for each element for all four u s g s standards the accuracy of this final calibration is estimated to be better than 5 absolute and it has been used to determine the above elemental abundances in 29 international rock standards five of the ree have been determined by interpolation from chondrite normalised plots

magma decompression rates during explosive eruptions of kīlauea volcano hawaii recorded by melt embayments the decompression rate of magma as it ascends during volcanic eruptions is an important but poorly constrained parameter that controls many of the processes that influence eruptive behavior in this study we quantify decompression rates for basaltic magmas using volatile diffusion in olivine hosted melt tubes embayments for three contrasting eruptions of k lauea volcano hawaii incomplete exsolution of h2o co2 and s from the embayment melts during eruptive ascent creates diffusion profiles that can be measured using microanalytical techniques and then modeled to infer the average decompression rate we obtain average rates of 0 05 0 45 mpa s 1 for eruptions ranging from hawaiian style fountains to basaltic subplinian with the more intense eruptions having higher rates the ascent timescales for these magmas vary from around 5 to 36 min from depths of 2 to 4 km respectively decompression exsolution models based on the embayment data also allow for an estimate of the mass fraction of pre existing exsolved volatiles within the magma body in the eruptions studied this varies from 0 1 to 3 2 wt but does not appear to be the key control on eruptive intensity our results do not support a direct link between the concentration of pre eruptive volatiles and eruptive intensity rather they suggest that for these eruptions decompression rates are proportional to independent estimates of mass discharge rate although the intensity of eruptions is defined by the discharge rate based on the currently available dataset of embayment analyses it does not appear to scale linearly with average decompression rate this study demonstrates the utility of the embayment method for providing quantitative constraints on magma ascent during explosive basaltic eruptions

relationship between tremor and volcanic activity during the southeast crater eruption on mount etna in early 2000 1 the southeast crater of mount etna italy was characterized by a violent eruptive activity between 26 january and 24 june 2000 this activity produced 64 lava fountain episodes with repose periods from 3 hours to 10 days we estimated a volume of about 15 20 106 m3 lava and at least 2 3 106 m3 of tephra we compared the paroxysmal volcanic activity to its associated seismic signature the high number of events highlighted a strict correlation between tremor and volcanic activity seismic and volcanic characteristics such as the frequency of occurrence the duration of lava fountains and the associated tremor energy suggested the subdivision of the studied period into two stages separated by the 20 february event combining volcanic with seismic data we observed some useful relationships among lava fountain height sustained column height and reduced displacement in addition we found that the entire episode was well correlated with the duration of the amplitude increase computing the tremor energy linked to each event the total energy associated with lava fountains episodes results in 76 of the energy released during the whole period finally the different ratios among the overall spectral amplitude of the seismic signals of the stations located at different altitudes suggested to us the elaboration of a simple qualitative model to explain the dynamic behavior of the tremor source during the whole episode

importance of melt fraction and source rock composition in crustal genesis the example of two granitic suites of northern portugal in the montalegre area northern portugal two varieties of syn to late tectonic hercynian aluminous granitoids are distinguished 1 1 muscovite rich two mica granites forming many successively emplaced bodies with little chemical variation the chemical characteristics of these units suggest partial melting of various crustal rocks under distinct p t and water saturation conditions there has been no homogenization between the different melt batches the rocks contain very few restitic minerals segregation processes may have operated either in the source rock or in an early magmatic stage 2 2 a cordierite biotite and muscovite bearing granitic body its mineralogical composition is extremely heterogeneous and it contains many xenoliths the genesis of this granite results essentially from partial melting of peraluminous orthogneisses the melt fraction was higher than the rheological critical melt percentage rcmp during anatexis the rigid framework of the source rock broke down leading to migration of both melt and residual minerals towards upper crustal levels the heterogeneity of the resulting granite is mostly related to an incomplete separation of residual crystals and melt the existence of biotite and cordierite rich samples is the result of accumulation of residual minerals during the magma emplacement this study emphasizes the role of the source rock composition which controls the degree of partial melting at given p t and water saturation conditions during crustal melting the strong geochemical differences between the two kinds of granitoids are related to the near absence of residual minerals in the muscovite rich granites and to the presence of residual minerals in the cordierite bearing granite it is suggested that the muscovite rich granites are mostly low melt fraction rcmp the presence of many residual crystals alkali feldspars and plagioclases as well as dark minerals in the cordierite granite implies a high viscosity of the melts and therefore water undersaturated melting conditions

the role of syn eruptive vesiculation on explosive basaltic activity at mt etna italy abstract we investigated the dynamics of explosive activity at mt etna between 31 august and 15 december 2006 by combining vesicle studies in the erupted products with measurements of the gas composition at the active summit crater the analysed scoria clasts present large connected vesicles with complex shapes and smaller isolated spherical vesicles the content of which increases in scoriae from the most explosive events gas geochemistry reports co 2 so 2 and so 2 hcl ratios supporting a deep derived gas phase for fire fountain activity by integrating results from scoria vesiculation and gas analysis we find that the highest energy episodes of mt etna activity in 2006 were driven by a previously accumulated co 2 rich gas phase but we highlight the lesser role of syn eruptive vesicle nucleation driven by water exsolution during ascent we conclude that syn eruptive vesiculation is a common process in etnean magmas that may promote a deeper conduit magma fragmentation and increase ash formation

melt inclusions track pre eruption storage and dehydration of magmas at etna at mount etna italy vigorous gas rich eruptions in a d 2001 2002 and 2003 were followed by gas poor eruptions in 2004 2006 and 2007 analyses of volatile co2 h2o s cl f semivolatile cu and involatile nb la elements trapped in olivine hosted melt inclusions from these latest eruptions reveal the effects of the sustained interaction between a percolating gas phase and the stored magma melt inclusion compositions indicate that magmas erupted from 2004 to 2007 were residual from the 2001 2003 eruptions and show significant evolution in the volatile content of the melt these melt inclusion observations and variations in the c s of volcanic gases can be accounted for if melts reequilibrated with co2 rich gases during storage and prior to entrapment as melt inclusions sustained gas percolation caused loss of water and enhancement of co2 in the evolving melt and may strongly influence the behavior of cu which potentially partitions into the gas phase vapor melt interactions during magma storage are important controls on magma evolution at persistently degassing volcanoes

explosive activity at mt etna summit craters and source modeling by using high precision continuous tilt we investigated the relationships between modelled strain produced by explosive activity through a volcanic conduit observed paroxystic episodes on mt etna and high precision continuous tilt signals recorded during such events from the tilt monitoring network the tilt changes detected during two different explosive episodes were compared with those calculated from analytical models of ground deformation in order to constrain source properties the july 22 1998 subplinian explosion from voragine crater produced small tilt changes order of 0 5 1 5 rad recorded over the entire volcano edifice implying a small storage at nearly 2 5 km below sea level the 1998 2000 period was characterized by tens of spectacular lava fountains from the south east crater very small tilt change 0 1 rad was recorded by a single station on the high north eastern flank of mt etna and indicated the action of a limited and shallow conduit with 1 5 1 9 km depth these results provide a contribution to better infer the shallow plumbing system beneath mt etna

unravelling the processes controlling gas emissions from the central and northeast craters of mt etna abstract we measured volcanic gas emissions from the northeast crater nec and central crater cc of mount etna on 21st july 2008 and 3rd and 31st august 2009 using a novel lightweight open path fourier transform infrared spectrometry op ftir in active mode with a portable infrared lamp contemporaneously we measured the so2 flux of the total gas emission released by the combined summit craters 14 km downwind and the so2 flux emitted by the nec measured at the summit combining these data we determined the flux of the major volcanic components h2o co2 so2 hcl and hf emitted individually from cc and nec craters the results reveal similar so2 hcl ratios but distinct co2 so2 ratios 1 3 and 10 9 for nec and cc respectively and an order of magnitude greater co2 flux from the cc compared with the nec a simple model in which the nec branches from a central feeding conduit at a depth of 2 km can reproduce these observations we highlight that in such a system short term variations in co2 so2 ratios at each crater can occur due to minor variations in the magma gas flux entering each conduit at the branch without an overall change in magma supply co2 so2 variations measured at individual craters may therefore be unrepresentative of the volcanic system and require cautious interpretation monitoring of the total co2 and so2 fluxes emitted from each crater is on the contrary an optimal monitoring strategy and can be achieved using a combination of co2 so2 instruments and so2 imaging cameras

bulk mineralogy of individual micrometeorites determined by x ray diffraction analysis and transmission electron microscopy abstract bulk mineralogy of individual fine grained micrometeorites from 50 to 200 m in diameter was determined on the basis of the powder x ray diffraction patterns and the observation of internal textures by a transmission electron microscope tem x ray diffraction analysis of 56 micrometeorites indicated that 42 11 and 3 samples are olivine rich pyroxene rich and phyllosilicate rich micrometeorites respectively among the phyllosilicate rich micrometeorites one contains saponite and other two contain serpentine no samples contain both saponite and serpentine we found that saponite rich micrometeorite was weakly heated which results in shrinkage of 001 basal spacing of saponite down to 9 7 a and that cronstedtite which is commonly contained in cm chondrites occurs in serpentine rich micrometeorites micrometeorites that consist entirely of anhydrous minerals and amorphous phases are predominant in the samples studied the major phases of such micrometeorites are olivine low ca pyroxene magnetite and fe sulfide and the average abundances are 65 17 11 and 7 wt respectively when the total abundance of the four minerals are normalized to 100 wt the relative mineral abundance varies greatly between samples low ca pyroxene olivine ratios range from 0 to 3 5 with a mean of 0 3 tem observations of inner portions of some micrometeorites revealed that they are aggregates of very small equigranular grains 100 nm of olivine magnetite or low ca pyroxene olivine magnesiowustite the textures are very similar to those of hydrous carbonaceous chondrite that was experimentally heated to temperature below melting point thus suggesting that the micrometeorites had been hydrous particles but were decomposed by the brief heating upon atmospheric entry it is newly found that magnesiowustite was formed in micrometeorites instead of magnetite as a product of phyllosilicate decomposition under low oxygen fugacity the decomposed hydrous micrometeorites gave two types of characteristic x ray diffraction patterns 1 broad olivine and magnetite reflections or 2 variable intensities of magnesiowustite reflections together with magnetite low ca pyroxene and olivine reflections twenty nine olivine or pyroxene rich micrometeorites showed such diffraction patterns thus suggesting that more than half of micrometeorites investigated must be decomposed hydrous particles the results confirmed that hydrous dust particles are much more abundant in the interplanetary space than in the micrometeorites recovered on the earth

multidisciplinary investigation on a lava fountain preceding a flank eruption the 10 may 2008 etna case a multidisciplinary approach integrating a wide data set ranging from bulk rock compositions of the erupted products to volcanic tremor long period events and tilt and gravity signals is used to investigate the source depth and magma dynamics of the 10 may 2008 lava fountain at southeast crater sec of mount etna the investigation was undertaken in the framework of the previous 2007 explosive activity as well as the subsequent effusive eruption beginning 13 may 2008 and lasting up to july 2009 all the data concur in indicating that the 10 may lava fountain was generated by the fragmentation of a foam layer trapped at the top of a shallow reservoir about 1500 1700 m below the summit of sec the shift from the episodic strombolian lava fountain activity occurring in 2007 at sec to the more powerful 10 may 2008 lava fountain is explained by the intrusion of a new more primitive magma into the shallow reservoir data also indicate that an attempted magma intrusion east of the summit area occurred during the 10 may fire fountain this event caused the fracturing and weakening of the surrounding rocks and created a preferential pathway for the penetration of the magma that only 3 days later started to feed the 2008 2009 effusive eruption

meteoritic event recorded in antarctic ice during systematic sampling of volcanic ash tephra layers at a well known antarctic meteorite collection site the allan hills main ice field a band of unusually dark and rounded many spheroidal particles was discovered this debris layer bit 58 extends parallel to the stratigraphy of the ice established from the tephra bands apparently marking a single depositional event the shapes internal texture major element composition and levels of cosmogenic nuclides of particles from within bit 58 all strongly suggest that this material represents ablation debris from the passage of a large h group ordinary chondrite preliminary cosmogenic isotope dating suggests an age of 2 8 ma implying that the east antarctic ice sheet has been stable since that time the relationship of the bit 58 layer to known impact events is not clear

variations in co2 emissions at a mud volcano at the southern base of mt etna are they due to volcanic activity interference or a geyser like mechanism mud volcanoes are often associated with large areas of co2 and ch4 emission that are potentially dangerous due to sudden paroxysmal gas and mud eruptions despite the interest in understanding such natural environments they have not yet been thoroughly investigated and a single interpretative framework remains to be elaborated this lack of knowledge may be due to the difficulty in measuring in plume co2 as there is very little contrast with atmospheric co2 coupled with the complex organizational strategies required for long term monitoring this work features three different methods that were used to evaluate the co2 flux at the salinelle mud volcano in the foothills of mt etna italy carried out periodically from december 2013 to april 2018 we computed in plume co2 flux indirectly using a tunable laser and a portable multigas and directly measuring the gas volumetric flux from bubbling pools the morphological variations of the mud field were recorded using unmanned aerial vehicle uav imagery which provided information on the migration of vents in relation to the observed variations in measured gas output our analysis shows that the three methods gave comparable values indicating the feasibility of this approach our findings suggest a pseudo cyclical pattern in the bulk co2 emitted at salinelle introducing a new interpretation of the processes involved in mud volcano dynamics we theorize that the periodic variation of the gas emitted at the salinelle may be attributed to a geyser like mechanism that may be subject to interruption or changes in magnitude by volcanic or seismic events

geochemical investigations of the origin of the manaslu leucogranite himalaya nepal the himalayan orogeny is characterized by an intraplate subduction zone the thrusting of the tibetan slab over the foreland is probably responsible for the origin of the manaslu type leucogranites this geochemical study tries to examine the crustal origin of the granite to verify whether the paragneisses of the tibetan slab are the most probable parent material and to determine the subsequent petrogenetic processes the rb sr systematics suggest that 1 1 the scatter of data points in the 87sr86srvs 87rb86sr diagram may be due to the heterogeneity of the initial 87sr86sr ratios 2 2 the initial isotopic ratios are very high 0 730 0 760 and are in agreement with those of the gneisses of the tibetan slab at the time of the melting pb isotopic ratios are homogeneous they are also consistent with a crustal prehistory the ree and th contents are unexpectedly low in comparison with the much higher contents of the parent material monazite left in the residue of melting or more probably extracted in an early stage of the magmatic history may explain the observed ree and th abundances alternatively field observations show that the emplacement of the granite has been accompanied by a very strong hydrothermal activity in consequence the low ree and th contents of the granite could also be due to the loss by solution during prolonged fluid circulation throughout the granitic melt and the sr and pb isotope distribution to the effect of late to post magmatic fluids the isotopic character of which was determined by the underlying tibetan slab

lava fountains during the episodic eruption of south east crater mt etna 2000 insights into magma gas dynamics within the shallow volcano plumbing system mt etna in sicily italy is well known for frequent effusive and explosive eruptions from both its summit and flanks south east crater se crater one of the four summit craters has been the most active in the last 20 years and often produces episodic lava fountains over periods lasting from a few weeks to months the most striking of such eruptive phases was in 2000 sixty four lava fountains separated by quiescent intervals and sometimes associated with lava overflows occurred that year between january and june a time period during which we consider the volcano to have been in episodic eruption this paper presents mainly results of petrochemical investigations carried out on both tephra and lavas collected during a number of the lava fountain episodes in 2000 the new data have been integrated with volcanological and seismic information in order to correlate the features of the eruptive activity with magma gas dynamics in the plumbing system of se crater the main findings allow us to characterise the 2000 episodic eruption in the framework of the recent se crater activity in particular we infer that the onset of the 2000 eruption was triggered by the ascent of new more primitive and volatile rich magma that progressively intruded into the se crater reservoir where it mixed with the resident more evolved magma furthermore we argue that the 2000 se crater lava fountains largely resulted from the instability of a foam layer accumulated at the top of the underlying reservoir and rebuilt prior to each episode in agreement with the collapsing foam model for lava fountains

magma ascent and the pressurization of mount etna s volcanic system after a period of deflation during the 1991 1993 flank eruption mount etna underwent a rapid inflation seismicity and ground deformation show that since 1994 a huge volume of magma intruded beneath the volcano producing from 1998 onward a series of eruptions at the summit and on the flank of the volcano the last of these started on 27 october 2002 is still in progress and can be considered one of the most explosive eruptions of the volcano in recent times here we show how geodetic data and seismic deformation between 1994 and 2001 indicate a radial compression around an axial intrusion consistent with a repressurization of mount etna s plumbing system at a depth of 6 to 15 kilometers which triggered most of the seismicity and provoked the dilatation of the volcano and the recent explosive eruptive activity

s cl f degassing pattern of water rich alkali basalt modelling and relationship with eruption styles on mount etna volcano abstract our knowledge of the degassing pattern of sulphur chlorine and fluorine during ascent and eruption of basaltic magmas is still fragmental and mainly limited to water poor basalts here we model and discuss the pressure related degassing behaviour of s cl and f during ascent differentiation and extrusion of h2o co2 rich alkali basalt on mount etna sicily as a function of eruptive styles our modelling is based on published and new melt inclusion data for dissolved volatiles co2 h2o s cl f in quenched explosive products from both central conduit 1989 2001 and lateral dyke 2001 and 2002 eruptions pressures are obtained from the dissolved h2o and co2 concentrations and vapour melt partition coefficients of s cl and f are derived from best fitting of melt inclusion data for each step of magma evolution this allows us to compute the compositional evolution of the gas phase during either open or closed system degassing and to compare it with the measured composition of emitted gases we find that sulphur chlorine and fluorine begin to exsolve at respective pressures of 140 mpa 100 mpa and 10 mpa during etna basalt ascent and are respectively degassed at 95 22 55 and 15 upon eruption pure open system degassing fails to explain gas compositions measured during either lateral dyke or central conduit eruptions instead closed system ascent and eruption of the volatile rich basaltic melt well accounts for the time averaged gas composition measured during 2002 type lateral dyke eruptions s cl molar ratio of 5 1 35 bulk cl loss extensive magma fragmentation during the most energetic fountaining phases enhances cl release 55 and produces a lower s cl ratio of 3 7 as actually measured comparatively slower magma rise in the central conduits of etna favours both sulphide saturation of the melt and greater chlorine release 55 resulting in a distinct s cl evolution path and final ratio in eruptive gas in both eruption types any previous bubble melt separation at depth leads to increased s cl and s f ratios in emitted gas high s cl ratios measured during some discrete eruptive events can thus be explained by transitions from closed deep to open shallow system degassing with differential gas transfer extending down to 2 km depth below the vents this depth coincides with the base of the volcanic pile where structural discontinuities and the high magma vesicularity 60 may favour separate gas flow finally the excess s cl f gas discharge through etna summit craters during non eruptive periods requires a mixed supply from shallow magma degassing in the volcanic conduits and deeper derived so2 rich bubbles from the sub volcano plumbing system our modelling provides a useful reference framework for interpreting the monitored variations of s cl and f in mount etna gas emissions as a function of volcanic activity more broadly the observations made for s cl and f degassing on etna may apply to other basaltic volcanoes with water rich magmas such as in arcs

patterns in the recent 2007 2008 activity of mount etna volcano investigated by integrated geophysical and geochemical observations 1 seismic deformation and volcanic gas observations offer independent and complementary information on the activity state and dynamics of quiescent and eruptive volcanoes and thus all contribute to volcanic risk assessment in spite of their wide use there have been only a few efforts to systematically integrate and compare the results of these different monitoring techniques here we combine seismic volcanic tremor and long period seismicity deformation gps and geochemical volcanic gas plume co2 so2 ratios measurements in an attempt to interpret trends in the recent 2007 2008 activity of etna volcano we show that each eruptive episode occurring at the southeast crater sec was preceded by a cyclic phase of increase decrease of plume co2 so2 ratios and by inflation of the volcano s summit captured by the gps network these observations are interpreted as reflecting the persistent supply of co2 rich gas bubbles and eventually more primitive magmas to a shallow depth of 1 2 8 km asl magma storage zone below the volcano s central craters ccs overpressuring of the resident magma stored in the upper ccs conduit triggers further magma ascent and finally eruption at sec a process which we capture as an abrupt increase in tremor amplitude an upward 2800 m asl and eastward migration of the source location of seismic tremor and a rapid contraction of the volcano s summit resumption of volcanic activity at sec was also systematically anticipated by declining plume co2 so2 ratios consistent with magma degassing being diverted from the central conduit area toward sec

tektites and microtektites key facts and inferences abstract tektites are generally small black rounded silicate glass bodies found scattered over several widely separated areas of the earth s surface called strewn fields four major tektite strewn fields are known 1 australasian 2 ivory coast 3 czechoslovakian and 4 north american tektites from these four strewn fields have been dated at 0 7 1 15 and 34 ma respectively most tektites are splash forms i e spheres teardrops dumbbells etc but some have undergone a second period of melting to produce ablated forms tektites with a blocky layered appearance are called muong nong types microtektites microscopic tektites belonging to the australasian ivory coast and north american strewn fields have been found in deep sea sediments the geographic occurrence and abundance of microtektites at each site have been used to determine the size and mass of each strewn field the australasian ivory coast and north american strewn fields contain 100 million 20 million and 1 billion tonnes of glass respectively although tektites resemble obsidian they can be distinguished from terrestrial volcanic glasses by their composition and petrography tektites for example are drier than volcanic glasses and have higher feo fe 2 o 3 ratios in addition tektites unlike volcanic glasses contain lechatelierite particles sio 2 glass and are devoid of primary crystallites although some authors favor a lunar volcanic origin most of the compositional and petrographic data indicate a terrestrial impact origin the major trace and isotopic compositions of tektites indicate that the parent material was a terrestrial sedimentary deposit and the presence of lechatelierite coesite and shocked relict inclusions favors an impact origin furthermore two tektite strewn fields have been associated with known impact craters and tektites from one strewn field have been found associated with impact ejecta unlike the cretaceous tertiary boundary layer microtektite layers are not associated with mass extinctions or iridium anomalies

open path ftir spectroscopy of magma degassing processes during eight lava fountains on mount etna in june july 2001 a series of 16 discrete lava fountain paroxysms occurred at the southeast summit crater sec of mount etna preceding a 28 day long violent flank eruption each paroxysm was preceded by lava effusion growing seismic tremor and a crescendo of strombolian explosive activity culminating into powerful lava fountaining up to 500 m in height during 8 of these 16 events we could measure the chemical composition of the magmatic gas phase h2o co2 so2 hcl hf and co using open path fourier transform infrared op ftir spectrometry at 1 2 km distance from sec and absorption spectra of the radiation emitted by hot lava fragments we show that each fountaining episode was characterized by increasingly co2 rich gas release with co2 so2 and co2 hcl ratios peaking in coincidence with maxima in seismic tremor and fountain height whilst the so2 hcl ratio showed a weak inverse relationship with respect to eruption intensity moreover peak values in both co2 so2 ratio and seismic tremor amplitude for each paroxysm were found to increase linearly in proportion with the repose interval 2 6 days between lava fountains these observations together with a model of volatile degassing at etna support the following driving process prior to and during the june july 2001 lava fountain sequence the shallow 2 km magma reservoir feeding sec received an increasing influx of deeply derived carbon dioxide likely promoted by the deep ascent of volatile rich primitive basalt that produced the subsequent flank eruption this co2 rich gas supply led to gas accumulation and overpressure in sec reservoir generating a bubble foam layer whose periodical collapse powered the successive fountaining events the anti correlation between so2 hcl and eruption intensity is best explained by enhanced syn eruptive degassing of chlorine from finer particles produced during more intense magma fragmentation

extraterrestrial water in micrometeorites and cosmic spherules from antarctica an ion microprobe study the d h ratios and water contents were measured by ion microprobe analysis in 52 individual antarctic micrometeorites amms and 10 antarctic cosmic spherules acss containing nuggets of iron hydroxide cops phase in amms d values vary from 366 to 249 and water contents lie between 0 4 3 7 wt the cops nuggets in cosmic spherules have high water contents 2 to 8 wt and exhibit d values from 144 to 167 which is indicative of an extraterrestrial origin of their constituent water the silicate portion of acss also contain extraterrestrial h equivalent to 0 l to 1 2 wt water deuterium exchange experiments were performed with isotopically spiked water these experiments demonstrate that water in mineral phases of amms and acss is indigenous and does not result from contamination during residence in antarctic ice the frequency distribution of d h ratios in amms allows us to further narrow the relationship between amms and carbonaceous chondrites to cm and ci chondrites but contrasts with that of stratospheric interplanetary dust particles idps of similar sizes from 10 to 50 m the relatively narrow range of d h ratios measured in amms as well as in acss which are more resistant and thus less susceptible to collection biases suggests that d rich idp like particles are very rare in our amms collections this indicates that these d rich grains might constitute a minor fraction of the micrometeorite flux in the interplanetary medium and that possible collection biases in antarctica would not be responsible for their strong depletion in the amms collections