wide aperture beamforming of depth phases by timescale contraction abstract teleseismic depth phase signals can be combined with constructive interference from stations spaced as much as 1000 km apart each trace is first deconvolved using an operator based on the p phase of that trace then its timescale is stretched or contracted to eliminate the moveout of pp p time with distance traces can then be added with constructive interference of depth phases out to 10 or more angular distance between the stations on the focal sphere depth phases pp or sp representing hypocentral depths ranging from 6 to 204 km were found using canadian national seismograph network cnsn data for 45 events recorded at ranges of 2000 to 10 800 km which had been reported in the reviewed event bulletins reb of the prototype international data center pidc including 23 events for which the reb reported no depth phases for 28 events for which a catalog depth reb or pde from usgs was available for comparison 18 had depths agreeing either within 6 km or within 15 7 can be explained by assuming an sp phase was misassociated as pp 1 is just outside the error bar of the free depth reported in the reb and only 2 disagree significantly thus using only canadian data depth phases were found by beamforming for many events for which no depth phases had been found by the pidc using worldwide data including arrays the depth phase beamforming method has the potential of substantially increasing the number of earthquakes for which teleseismic depth phases can be detected

degassing processes at stromboli volcano inferred from short lived disequilibria 210 pb 210 bi 210 po in volcanic gases abstract volcanic aerosols and gases released by three active craters at stromboli volcano have been regularly collected since 1985 in this paper we present new evidence of the high volatility of some nuclides among radon daughters 210pb 210bi and 210po which are strongly fractionated leading to significant radioactive disequilibria in volcanic exhalations the very low volcanic activity in october 1996 allowed a separate sampling of each crater plume for the first time remote sampling of the bulk plume were also performed these data show that the chemical composition of volcanic aerosols remains constant within the first few hundred meters from their source vents ensuring the validity of remote sampling when the activity does not allow one to approach the active craters moreover it appears that there is no differentiation of gases from one crater to another suggesting that the geometry of the upper plumbing system of the volcano is rather simple gases being directly emitted from a shallow magma chamber without significant cooling inside the edifice on the basis of the assumption of a continuously replenished shallow magma reservoir in steady state we propose a dynamic model of degassing accounting for the variations of radionuclide contents and ratios observed in the gas phase since 1985 this model allows us to relate these variations to changes in the magma chamber dynamics namely the magma residence time inside the chamber and the escape time of gases from it both parameters being closely linked to the volcanic activity while gases are always emitted within a few hours after bubble nucleation suggesting that the chamber is no deeper than a few hundred meters magma residence time varies from less than 20 days during eruptive periods highly explosive or effusive periods to more than 200 days before the 1985 eruption the latter figure is explained by the storage at shallow depth of a poorly renewed magma batch that fed the eruption the variations of the residence time observed over the studied period suggest that the steady state dynamics of the stromboli magma chamber is sustained for rather short periods of a few months at most on basis of the knowledge of the deep undegassed magma supply and the magma residence time we estimate the volume of the shallow magma chamber at about 7 2 10 5 m 3 the good agreement of our results with previous estimates based on both geochemical and geophysical studies suggests that the measurement of radioactive disequilibria in the gas phase provides a robust tool for a deeper understanding of the volcanic activity and the magma dynamics beneath active volcanoes

loess stratigraphy using palaeomagnetism application to the poiana ciresului archaeological site romania abstract palaeomagnetic investigations were carried out at the archaeological site of poiana ciresului romania to check whether the loess records a reliable palaeomagnetic signal and to compare this signal to reference data the sediments are composed of loess and loess like sediments pedogenic alterations and a pronounced cultural layer occur in the section the archaeology bearing sedimentary geoarchive spans the time interval from ca 20 to ca 55 ka and was dated mainly by 14c and luminescence techniques the record of geomagnetic palaeosecular variation from this european loess site is discussed the presented palaeomagnetic record bears analogies to data from lac du bouchet france and is a reliable high resolution record mean sedimentation rates are ca 20 cm ky of palaeosecular variation the results imply that european loess geoarchives may record palaeosecular variation features even if loess is pedogenically altered the palaeosecular variation pattern of loess is here employed as a stratigraphic tool

optical dating of romanian loess a comparison between silt sized and sand sized quartz abstract the loess palaeosol sequence near mircea vod dobrogea se romania is thought to comprise at least five glacial interglacial cycles it is considered as one of the most significant records of late quaternary environmental and climatic change in the region age information for the sequence was previously obtained through time depth modeling of magnetic susceptibility data and optically stimulated luminescence dating osl of fine silt sized 4 11 m quartz this study documents the granulometric properties of the sequence and compares the osl characteristics and age of fine sand sized 63 90 m quartz to those of silt sized quartz osl signals from both sand and silt sized quartz are dominated by a thermally stable fast decaying component a suite of laboratory test confirms that the single aliquot regenerative dose sar protocol is suitable for these samples each grain size fraction yields a set of optical ages that is consistent with the stratigraphic position of the samples the ages obtained using sand sized grains however are up to 70 higher than those obtained using silt sized quartz the discrepancy in age results is not understood as according to procedural tests the osl signal from both fractions should be suitable for dating the deposits as such it cannot be established whether the uppermost weakly developed palaeosol was formed during mis3 or mis5 and if the rate of loess accumulation varied during the last glacial only by using standard sar osl techniques both sets of ages do confirm however that the first well developed palaeosol s1 is of last interglacial age

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

geochemistry and tectonic development of cenozoic magmatism in the carpathian pannonian region this review considers the magmatic processes in the carpathian pannonian region cpr from early miocene to recent times as well as the contemporaneous magmatism at its southern boundary in the dinaride and balkans regions this geodynamic system was controlled by the cretaceous to neogene subduction and collision of africa with eurasia especially by adria that generated the alps to the north the dinaride hellenide belt to the east and caused extrusion collision and inversion tectonics in the cpr this long lived subduction system supplied the mantle lithosphere with various subduction components the cpr contains magmatic rocks of highly diverse compositions calc alkaline k alkalic ultrapotassic and na alkalic all generated in response to complex post collisional tectonic processes these processes formed extensional basins in response to an interplay of compression and extension within two microplates alcapa and tisza dacia competition between the different tectonic processes at both local and regional scales caused variations in the associated magmatism mainly as a result of extension and differences in the rheological properties and composition of the lithosphere extension led to disintegration of the microplates that finally developed into two basin systems the pannonian and transylvanian basins the southern border of the cpr is edged by the adria microplate via sava and vardar zones that acted as regional transcurrent tectonic areas during miocene recent times major trace element and isotopic data of post early miocene magmatic rocks from the cpr suggest that subduction components were preserved in the lithospheric mantle after the cretaceous miocene subduction and were reactivated especially by extensional tectonic processes that allowed uprise of the asthenosphere changes in the composition of the mantle through time support geodynamic scenarios of post collision and extension processes linked to the evolution of the main blocks and their boundary relations weak lithospheric blocks i e alcapa and western tisza generated the pannonian basin and the adjacent styrian transdanubian and z rand basins which show high rates of vertical movement accompanied by a range of magmatic compositions strong lithospheric blocks i e dacia were only marginally deformed where strike slip faulting was associated with magmatism and extension at the boundary of adria and tisza dacia strike slip tectonics and core complex extension were associated with small volume miocene magmatism in narrow extensional sedimentary basins or granitoids in core complex detachment systems along older suture zones sava and vardar accommodating the extension in the pannonian basin and afterward pliocene quaternary inversion magmas of various compositions appear to have acted as lubricants in a range of tectonic processes

relationship between gases and volcanic activity of mount etna in 1986 the long lived 222rn decay products 210pb 210bi and 210po have been monitored in the plumes of several vents at mount etna sicily from may to october 1986 the results show that the four main craters of this volcano emit gases whose compositions are different from each other the 210bi 210pb ratios for the plumes have similar mean values close to 25 which correspond to a degassing time of 1 5 to 2 7 days according to the model of lambert et al 1985 86 in contrast 210po 210pb ratios have very different mean values in each plume 35 at the voragine crater 20 at the bocca nuova crater and 14 at the south east crater these figures enable us to calculate proportions of deep magma of 50 29 and 19 in the degassing cells of these craters respectively moreover the se crater appears to be a secondary degassing vent not directly related to the main magma reservoir the evolution of these ratios has been related to variations in volcanic activity

neogene quaternary magmatism and geodynamics in the carpathian pannonian region a synthesis in the carpathian pannonian region in neogene times westward dipping subduction in a land locked basin caused collision of two lithospheric blocks alcapa and tisia with the southeastern border of the european plate calc alkaline and alkaline magmatism was closely related to subduction rollback collision and extension from the spatial distribution of the magmatic activity four segments can be defined western segment magmatism occurring on the alcapa block central segment magmatism occurring on both alcapa and the tisia blocks south eastern segment and interior segment both on the tisia block most calc alkaline magmatism in the region resulted from melting of a heterogeneous asthenospheric mantle source modified by addition of fluids and sediment assimilation and fractionation processes at shallow crustal levels occurred in most of the segments strongly masking the deeper source processes long term subduction rollback and or delamination led to contamination of the asthenosphere beneath the western segment here large volume partial melts of the contaminated mantle caused underplating and crustal anatexis leading to mixing of mantle derived calc alkaline magmas with crustal melts in the central segment calc alkaline magmas were formed by subduction and rollback followed by back arc extension and slab breakoff avariable mantle source is indicated in the back arc setting and larger amount of fluid induced metasomatism source enrichment and assimilation nearer to the trench in the interior segment evolution from typical calc alkaline magmas to adakite like ones was related to extension due to fast rotations and transtensional tectonics here calc alkaline magmas formed by decompression melting of a heterogeneous crust mantle lithosphere while adakite like melts resulted from fliud dominated melting of the lithosphere along the south eastern segment slab breakoff was responsible for the generation of typical calcalkaline magmas but in the extreme south of the segment shallow level tearing of the slab followed breakoff strike slip tectonics allowed the rise of hot asthenosphere and generation of adakite like magmas via slab melting along the torn edge of the east european plate alkalic basaltic volcanism with an oib like asthenosphere source followed the calc alkaline stage

characterization of ultrafine aerosol particles in mt etna emissions particulate emissions from mt etna in the fine size range below 100 nm were studied in june and september 1989 the aerosol particles were characterized by size concentration and photoelectric activity these quantities are sensitive to the physical and chemical properties of the magma concentrations varied from 104 to 107 cm 3 the size distributions peak below 20 nm radius and are very narrow the particles are generated mainly by nucleation and condensation of magmatic volatiles in a strong temperature gradient the photoelectric activity of these particles can indicate high magma levels and increased exsolution of volatiles it is therefore related to the observed activity of the respective crater and may be helpful as a prediction tool when used in conjunction with other volcano monitoring techniques

radioactive isotopes and trace elements in gaseous emissions from white island new zealand abstract measurements of the radioactivity of gases released by white island volcano show variations in 210 po concentrations with temperature in fumarolic gases and this is interpreted to be due to dilution of magmatic gases with vapours derived from an envelope of acid brines surrounding the vent system the degassing model derived for mount etna emissions is tested on white island magmatic gases the results are a short degassing time 2 days small degassing magma volume 5 10 6 m 3 and the following estimations of emanation coefficients pb 1 bi 2 7 cd 0 05 and cu 0 07 the initial content of s in the magma is estimated to be within the range 300 600 mg kg fluxes of trace metals kg day emitted by the volcano are estimated to be pb 125 bi 6 cu 300 and cd 9

radionuclides and sulfur content in mount etna plume in 1983 1995 new constraints on the magma feeding system abstract radionuclide activities 210pb 210bi 210po were investigated in mount etna plume from 1983 to 1995 at se crater the long term observation 12 years of the 210po 210pb ratio shows that it can behave as a degassing vent not directly related to the main magma reservoir depending on the magma level inside the volcano since 1992 the simultaneous determination of radionuclides and sulfur in the main plume results in new constraints on the degassing model of lambert et al earth planet sci lett 76 1986 185 the 210po so2 and 210pb so2 ratios enable us to identify two sources of 210po in the plume one is magmatic correlated with so2 the other one is an additional component issued from the decay of 210pb in the shallow degassing cell and depends directly on the residence time of the gases before their emission estimations of the volume of degassing magma the residence time of the gases and the proportion of undegassed magma renewing the shallow degassing cell are given for the period 1992 1995 during the 1992 eruption the rate of degassing magma volume is estimated to have been as high as 5 10 6 m 3 day and the volume of the shallow degassing magma reservoir about 0 5 km3 in 1994 and 1995 the rate of non erupted degassing magma volume was estimated to have been about 0 18 km 3 year during the entire 1983 1995 period only 15 20 of the degassed magma was erupted

tracing volcanic events in the ngrip ice core and synchronising north atlantic marine records during the last glacial period five basaltic tephra horizons have been identified in the ngrip ice core during the last glacial period geochemical analyses indicate that these tephras are of icelandic origin with one horizon identified as the faroe marine ash zone iii fmaz iii an important marker horizon in several marine records within the faroe islands margin the fmaz iii is a few millimetres thick and is constrained to 38 122 723 yr b2k before year ad 2000 according to the greenland ice core chronology gicc05 this event falls directly at the thermal peak of greenland interstadial 8 gi 8 and a marine ice correlation based on the position of this tephra suggests a close coupling of the marine and atmospheric systems at this time the remaining tephras originate from the eastern volcanic zone with the katla volcanic system pinpointed as the dominant source these are thought to represent previously unknown volcanic events which add considerably to our knowledge of icelandic volcanism during this period independent ages are assigned to these events and together with major element characterisation form the backbone of the tephrochronology framework presented here despite the identification of these tephras this study also demonstrates that the sulphate record may not always act as a suitable proxy for the identification of tephra horizons in ice core records

the campanian ignimbrite and codola tephra layers two temporal stratigraphic markers for the early upper palaeolithic in southern italy and eastern europe tephra layers from archaeological sites in southern italy and eastern europe stratigraphically associated with cultural levels containing early upper palaeolithic industry were analysed the results confirm the occurrence of the campanian ignimbrite tephra ci ca 40 cal ka bp at castelcivita cave southern italy temnata cave bulgaria and in the kostenki borshchevo area of the russian plain this tephra originated from the largest eruption of the phlegrean field caldera represents the widest volcanic deposit and one of the most important temporal stratigraphic markers of western eurasia at paglicci cave and lesser sites in the apulia region we recognise a chemically and texturally different tephra which lithologically chronologically and chemically matches the physical and chemical characteristics of the plinian eruption of codola a poorly known late pleistocene explosive event from the neapolitan volcanoes likely somma vesuvius for this latter we propose a preliminary age estimate of ca 33 cal ka bp and a correlation to the widespread c 10 marine tephra of the central mediterranean the stratigraphic position of both ci and codola tephra layers at castelcivita and paglicci help date the first and the last documented appearance of early upper palaeolithic industries of southern italy to ca 41 40 and 33 cal ka bp respectively or between two interstadial oscillations of the monticchio pollen record to which the ci and codola tephras are physically correlated corresponding to the greenland interstadials 10 9 and 5 in eastern europe the stratigraphic and chronometric data seem to indicate an earlier appearance of the early upper palaeolithic industries which would predate of two millennia at least the overlying ci tephra the tephrostratigraphic correlation indicates that in both regions the innovations connected with the so called early upper palaeolithic encompassing subsistence strategy and stone tool technology appeared and evolved during one of the most unstable climatic phases of the last glacial period on this basis the marked environmental unpredictability characterising this time span is seen as a potential ecological factor involved in the cultural changes observed

variations of cl f and s in mount etna s plume italy between 1992 and 1995 this study investigates data on the cl f and s concentrations of plume filter samples collected between 1992 and 1995 from mount etna the samples were collected during eruptive and noneruptive activity and show fairly constant cl f ratios but wide variation in the cl s ratios the determination of the cl f ratio between 5 and 14 allows an estimate of f degassing to be derived that ranges from 10 to 30 of the initial f content of the magma the variation in the cl s ratio fits an empirical two stage degassing model where gas with high cl s ratio is discharged during quiescient degassing and gas with low cl s ratios is discharged during eruptive degassing the typical permanent degassing occurs from a depth at which chlorine exsolution exceeds sulfur exsolution cl s 1 the opposite of this behavior is observed during eruptive periods when significant sulfur degassing occurs because magma degasses at near atmospheric pressure cl s 0 1 the cl s ratio in the plume characterizing the type of degassing has the potential to be a useful geochemical tool for monitoring the volcano

merapi volcano central java indonesia a case study of radionuclide behavior in volcanic gases and its implications for magma dynamics at andesitic volcanoes for more than 20 years volcanic gases have been regularly collected at merapi volcano indonesia and have been subsequently analyzed for their 210pb 210bi and 210po activities and so2 contents these new results show the high volatility of the three radionuclides in andesitic gases although their emanation coefficients 0 94 3 5 and 53 for 210pb 210bi and 210po respectively are significantly lower than those observed at basaltic volcanoes this emphasizes the major role of magma temperature on the degassing of these metals which are mainly transported in volcanic gases as pb chloride compounds and as bi and po metallic species radioactive disequilibria between 210pb 210bi and 210po in the gas phase are characteristic of degassing processes and gas paths within the edifice gases released at both gendol and woro fumarolic fields are of magmatic origin but their radionuclide content is strongly altered by secondary processes chemical reactions with surrounding brines and deposition of sublimates in the ground high temperature gases collected in the summit gas plume are of pure primary magmatic origin and are likely directly tapped in the degassing reservoir gases arising from the growing domes are strongly depleted in the most volatile isotopes and gas species this suggests that magma mostly degasses at depth in open system explaining why the volcano usually undergoes no explosive eruptions the gas flux at merapi is sustained by a deep magma supply which is twice the extrusion rate of lava unerupted degassed magma thus progressively accumulates beneath the summit yielding an overpressure which can trigger dome collapse without precursor

les debits de co2 et de so2 volcaniques dans l atmosphere la contribution des volcans a l atmosphere est reevaluee a 5 107 tonnes de so2 et 108 tonnes de co2 par an

tectonic significance of changes in post subduction pliocene quaternary magmatism in the south east part of the carpathian pannonian region the south eastern part of the carpathian pannonian region records the cessation of convergence between the european platform moesia and the tisza dacia microplate plio quaternary magmatic activity in this area in close proximity to the vrancea zone shows a shift from normal calc alkaline to much more diverse compositions adakite like calc alkaline k alkalic mafic na alkalic and ultrapotassic suggesting a significant change in geodynamic processes at approximately 3 ma we review the tectonic setting timing petrology and geochemistry of the post collisional volcanism to constrain the role of orogenic building processes such as subduction or collision on melt production and migration the calc alkaline volcanism 5 3 3 9 ma marks the end of normal subduction related magmatism along the post collisional c limani gurghiu harghita volcanic chain in front of the european convergent plate margin at ca 3 ma in south harghita magma compositions changed to adakite like calc alkaline and continued until recent times 0 03 ma interrupted at 1 6 1 2 ma by generation of na and k alkalic magmas signifying changes in the source and melting mechanism we attribute the changes in magma composition in front of the moesian platform to two main geodynamic events 1 slab pull and steepening with opening of a tear window adakite like calc alkaline magmas and 2 renewed contraction associated with deep mantle processes such as slab steepening during post collisional times na and k alkalic magmas contemporaneous post collisional volcanism at the eastern edge of the pannonian basin at 2 6 1 3 ma was dominated by na alkalic and ultrapotassic magmas suggesting a close relationship with thermal asthenospheric doming and strain partitioning related to the adriatic indentation similar timing magma chamber processes and volume for k alkalic shoshonitic magmas in the south apuseni mountains 1 6 ma and south harghita area at a distance of ca 200 km imply a regional connection with the inversion tectonics

geochemical characterization and origin of southeastern and eastern european loesses serbia romania ukraine abstract the loess paleosol sections of batajnica stari slankamen serbia mircea voda romania and stary kaydaky ukraine were geochemically characterized based on discriminant analysis of major and trace elements the ratios of al ti fe ti and al fe the a cn k ternary plot and element enrichment depletion relative to the average composition of the upper continental crust the origin of the loess material in the southern pannonian basin vojvodina the lower danube basin dobrudja and the dnieper area was evaluated by comparison with the representative element composition of possible source areas and by considering the geomorphodynamic setting also the background values of the initial magnetic susceptibility of the loesses were taken into account for the lower danube basin dobrudja and the ukraine paleowind direction was reconstructed based on the geographic distribution of sandy soil texture and dunes related to river systems finally loesses were evaluated as possible samples of the average upper continental crust our results show that danube and dnieper loess areas can be clearly distinguished the former reveal higher al and fe contents the latter higher si zr hf content and indications of effective mineral and grain size sorting we can confirm that vojvodina loess originated from danube alluvial material and loess of the dnieper area from glaciofluvial sediments of the fennoscandinavian ice sheet the dobrudja loess derived also predominantly from danube alluvium but shows significant contribution of a second loess source probably the glaciofluvial sediments of the ukraine this was forced by northerly katabatic winds from the fennoscandinavian ice sheet whereas wnw winds prevailed in the western walachian plain the studied loesses reflect the average composition of the upper continental crust yet biases exist due to selective mineral element enrichment and depletion in the course of previous sedimentary recycling phases respectively material of all studied loess deposits seems to derive originally from sedimentary rocks

marker horizons in the loesses of the carpathian basin abstract two tephra horizons are known in the middle and upper pleistocene loesses of the carpathian basin the older bag tephra has been described from numerous loess outcrops in hungary whereas the younger paks tephra has been described only from the brickyard of paks in southern hungary the most characteristic heavy minerals in these horizons are various clinopyroxenes occurring in different proportions the clinopyroxenes of the bag tephra are extremely rich in ca and al while the volcanic glass is rich in k indicating high k andesitic or shoshonitic volcanism based on comparative geochemical analyses the most likely origin of the bag tephra is the roman or the campanian volcanic fields in italy geochemical investigation of the paks tephra is in progress and preliminary results suggest the same source for this younger tephra in contrast to the tephra horizons the correlation of the numerous paleosols in some hungarian loess sections and their paleoenvironmental interpretation is possible only if they are based on very detailed micromorphological studies the age determination of the loesses containing the paleosols directly by thermoluminescence tl and infrared stimulated luminescence irsl and indirectly by 14 c based isotope work should provide a reliable basis for the identification of soil forming periods in different parts of the carpathian basin

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

the bag tephra a widespread tephrochronological marker in middle europe chemical and mineralogical investigations the bag tephra is a widespread tephra layer interbedded in quaternary loess deposits along the danubian valley of hungary and slovakia its age is poorly defined between 788 and 380 ka b p the glass and mineral composition micropumice clasts of phono tephrite and blocky shards of tephri phonolite associated with two kinds of clinopyroxene fassaitic diopside and salite is very distinctive this tephra could be used as a chronological marker as soon as its age is refined the probable origin is the middle italian volcanic area

middle and late pleistocene loess sequences at batajnica vojvodina serbia abstract loess sequences in the vojvodina region northern serbia reveal a continuous record of paleoclimatic variations during the middle and late pleistocene the most detailed stratigraphic information comes from remarkable exposures on the cliffs of the right danube bank from vukovar to belgrade the batajnica loess section has been recognized as one of the most complete middle and late pleistocene records in this region a more than 40 m thick loess paleosol succession represents environmental transition from relative thin loess layers and rubified soils in lower part of profile to thick loess and fossil chernozems characterizing the last three glacial interglacial cycles the proposed stratigraphic model is based on a detailed magnetic susceptibility ms record which is related to the deep sea isotope stratigraphy and on correlation with other eurasian loess records using the distinct ms pattern of selected loess paleosol couplets this new stratigraphic model suggests serious revision of previous chronological interpretations ms as function of depth shows a well known pattern of low values in loess and high values in paleosols indicating strong enhancement of magnetic minerals during soil formation with the exception of the recent soil v s0 which is strongly contaminated by archaeological artifacts the third paleosol v s3 reveals the highest values in ms and a very distinct double peak the rock magnetic signal at batajnica resembles the typical pattern of the enviromagnetic records determined from other eurasian loess sites the paleopedological interpretations rubification index values and rock magnetic record at batajnica yield valuable data for the reconstruction of paleoclimatic fluctuations for the last 5 glacial interglacial cycles at least moreover the record provides an important link between the classical central european loess sites and the central asian and chinese loess provinces

eruption of basalt and andesite lava degasses 222rn and 210po activities of 222rn and 210po were measured in a september 1983 basic andesite lava from arenal and a november 1983 basalt from kilauea starting 3 and 1 days after eruption respectively in both cases in growth patterns show that all rn volatalized during eruption po degassing also was complete at kilauea but only 84 10 at arenal

volcanic emission of radionuclides and magma dynamics 210pb 210bi and210po the last decay products of the238u series are highly enriched in volcanic plumes relative to the magma composition moreover this enrichment varies over time and from volcano to volcano a model is proposed to describe 8 years of measurements of mt etna gaseous emissions the lead and bismuth coefficients of partition between gaseous and condensed phases in the magma are determined by comparing their concentrations in lava flows and condensated volatiles in the case of volatile radionuclides an escaping time is calculated which appears to be related to the volcanic activity finally it is shown that that magma which is degassing can already be partly degassed it should be considered as a mixture of a few to 50 of deep non degassed magma with a well degassed superficial magma cell

the campanian ignimbrite y5 tephra layer a regional stratigraphic marker for isotope stage 3 deposits in the lower danube region romania a number of volcanic ash layers embedded in pleistocene loess and fluvial deposits of the lower jiu and olt valleys in south western romania have been analyzed for glass chemical compositions and general chronological relations the wds epma chemical analyses document remarkably similar major and minor element compositions at the four investigated sites and total alkali silica diagrams ascribe these volcanic ashes a phonolite to trachyte affinity a comparison with the quaternary carpathian volcanism chemical data refutes this volcanic field as the primary source even though earlier works have tentatively taken some of these volcanic ashes as evidence of volcanic activity in this particular field instead the chemical data suggest an origin in the campi flegrei volcanic province in italy and a comparison with chemical data from proximal and distal outcrops of the campanian ignimbrite y5 tephra confirm that the ash layers presented here are distal occurrences of this widespread tephra layer the campanian ignimbrite y5 tephra is the product of one of the largest late quaternary explosive events in the mediterranean and is consistently dated elsewhere to about 39 40 ka it is one of the most important chronologic stratigraphic markers of western eurasia that provide an independent basis for establishing age depth relationships for the embedding deposits optical luminescence age estimates obtained at two of the investigated sites further confirm that these volcanic ash occurrences represent a regionally synchronous depositional event around 40 ka these results highlight the important role that the campanian ignimbrite y5 tephra could play as marker horizon at sub continental scale providing that more potential tephra locations such as these from the pleistocene sedimentary deposits in the lower danube region are chemically and chronologically constrained

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

fluctuations of the campanian explosive volcanic activity south italy during the past 190 000 years as determined by marine tephrochronology abstract a statistical analysis of the time variations of the frequency of explosive events is derived from the detailed record of marine tephra in deep sea sediment cores of the central mediterranean sea the sequence of campanian events south italy shows several volcanic pulses during the past 190 000 years which were compared to the continental data these episodes which match the different phases of the geochemical evolution of magmas in this area occurred with a 23 kyr periodicity this may be related to the life time of the magma chambers involved in this area with such time cycles precessional forcing of the volcanic activity and or glacio eustatic pressure variations may be envisaged as causal phenomena

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

origin of fumarolic fluids emitted from a nonerupting volcano radionuclide constraints at vulcano aeolian islands italy the behaviour of 210po and 222rn in hot fumaroles on the crater rim at vulcano island was studied over 12 years 1980 1992 in order to infer the origin of the fluids the decreasing activity of 222rn observed since 1985 results from the mixing of the magmatic component with shallow water a part of 222rn in the gases is emitted by the surrounding rocks and carried along by the shallow water 210po is completely volatilized at t 450 c above this temperature its activity remains unchanged with increasing temperature 210po has two different origins one is magmatic correlated with 222rn the other one is produced by the sublimates deposited in the volcanic edifice from the magmatic 210po component the volume of degassing magma is estimated to be about either 170 000 m3 or 90 000 m3 day according to the model utilized in the first case the associated degassing time is about twelve days