continuous h2o co2 222rn and temperature measurements on merapi volcano indonesia abstract a set of analytical instruments consisting of a gas chromatograph for water and carbon dioxide an alpha scintillation counter to measure radon and a temperature sensor was especially designed and constructed to monitor volcanic gases and was successfully operated over weeks in the high temperature fumaroles at the summit of merapi volcano indonesia the analytical unit runs automatically and is remote controlled through a radio link over a period of several weeks concentrations of h 2 o and co 2 were measured every 35 min and rn activity was monitored at about 90 min intervals the fumarole temperatures were continuously recorded every minute from july 2000 to the end of january 2001 the composition and temperature of the gas emitted at merapi volcano show significant variations due to a regular stronger degassing of the magma concentrations of co 2 increase periodically while h 2 o concentrations decrease on the other hand rn activity rises with increasing atmospheric pressure and higher water concentrations after intensive rainfall infiltration of cold meteoric water into the volcanic edifice possibly causes an increase in the concentration of water vapour and a decrease in the temperature of the gases in the fumarole several seismic events recorded at merapi correlate with gas temperature

226ra in marine barite new constraints on supported 226ra abstract following the pioneering work of paytan et al a paytan et al geochim cosmochim acta 60 1996 4313 4319 new investigations have been undertaken on marine barite separated from central and western equatorial pacific sediments these investigations are designed to achieve a better quantification of supported 226 ra activities in the separated samples enabling the use of excess 226 ra 226 ra ex in marine barite as a tool for dating holocene sediments instrumental neutron activation analysis allowed first to measure significant 238 u activities in the separated samples attributable to highly insoluble minerals that like barite are resistant to the chemical treatment used in this study tio 2 minerals zircon monazite within these u rich minerals 226 ra activities are in secular equilibrium with 238 u second the study of the 226 ra signal in old barite samples that do not contain any residual 226 ra ex activities provided accurate constraints on the amount of 226 ra produced by unsupported 230 th the remaining 226 ra activities corrected for the 238 u contribution appeared to decrease with depth with a slope comparable to that defined by the bulk 230 th ex activities the consistency of this deep trend allowed its extrapolation upwards to the sediment top in order to obtain an estimate of the 226 ra activities produced by unsupported 230 th in the holocene barite samples the total correction for supported 226 ra in the holocene barite samples used in this study therefore consists of the sum of 226 ra activities in secular equilibrium with 238 u within minerals and 226 ra activities produced by unsupported 230 th thus estimated the resulting correction is low for samples separated from central equatorial pacific sediments compared with both the total 226 ra activities measured in barite and results of previous studies the magnitude of the correction is nevertheless higher for samples from western equatorial pacific sediments which display a lower barite purity the corrected 226 ra in barite profiles are in agreement with the general trend observed for long half life radionuclides with a similar mixed layer in the sediment top thus adding confidence in the use of this tool below the mixed layer the exponential decay of 226 ra ex activities in barite allowed the determination of sedimentation rates that agree with the estimates for the two investigated sites ultimately one of the main uses for the 226 ra in barite dating method will be its application to holocene sediments from the southern ocean where dating is often problematic

old radiocarbon ages in the southwest pacific ocean during the last glacial period and deglaciation marine radiocarbon 14c dates are widely used for dating oceanic events and as tracers of ocean circulation essential components for understanding ocean climate interactions past ocean ventilation rates have been determined by the difference between radiocarbon ages of deep water and surface water reservoirs but the apparent age of surface waters currently approximately 400 years in the tropics and approximately 1 200 years in antarctic waters might not be constant through time as has been assumed in radiocarbon chronologies and palaeoclimate studies here we present independent estimates of surface water and deep water reservoir ages in the new zealand region since the last glacial period using volcanic ejecta tephras deposited in both marine and terrestrial sediments as stratigraphic markers compared to present day values surface reservoir ages from 11 900 14c years ago were twice as large 800 years and during glacial times were five times as large 2 000 years contradicting the assumption of constant surface age furthermore the ages of glacial deep water reservoirs were much older 3 000 5 000 years the increase in surface to deep water age differences in the glacial southern ocean suggests that there was decreased ocean ventilation during this period

magnetic mapping ground penetrating radar surveys and magnetic susceptibility measurements for the study of the archaeological site of serra di vaglio southern italy in this work we present the results of a multidisciplinary study for characterising the archaeological site of serra di vaglio basilicata region southern italy the site includes an ancient native settlement arisen between the 8th and the 3rd century bc the investigation has been performed by means of the integrated use of three different high resolution and no invasive geophysical techniques magnetic mapping ground penetrating radar profiling gpr and magnetic susceptibility measurements the integrated approach allows us to detect buried archaeological structures in particular our results helped to define spatial pattern of the buried remains to define the geometry of the anthropogenic settlements and to obtain detailed information about the composition and the manufacturing processes of different building materials the archaeological excavations carried out in one of the investigated sites confirm the usefulness and the reliability of the integrated employment of different geophysical techniques for the archaeological study of ancient buried structures

joint geophysical measurements to investigate the rossano of vaglio archaeological site basilicata region southern italy abstract a high resolution geophysical survey was carried out in the archaeological site of rossano di vaglio basilicata region southern italy where an important ancient sanctuary is located it was built during the iv century b c and devoted to the goddess mephitis the sanctuary rises in an area affected by a multiple and retrogressive rototraslational landslide historically and presently subject to reactivation the main objective of this work was the identification of buried structures of archaeological interest in an area designated by the archaeological superintendence of the basilicata region the study was performed by means of the use of high resolution geophysical surveys in particular we made use of the joint application of three highly sensitive and non invasive geophysical techniques namely the geoelectrical the magnetic and the ground probing radar gpr methodologies in such a way we obtained two important results first we provided the archaeologists with information about the limits of the areas to be excavated second we could verify in real time the reliability of the geophysical results the experimental results showed four main magnetic anomalies in the area of study in agreement with the gpr results obtained for the same target finally a partial excavation test of the investigated area revealed a buried building structure located in correspondence of an anomaly identified by means of the geophysical prospecting

marine electrical resistivity tomography for shipwreck detection in very shallow water a case study from agropoli salerno southern italy abstract a marine electric resistivity survey was carried out over a submerged beach along the agropoli shore salerno italy to detect buried objects of archaeological interest below the sandy seabed we found a shipwreck a military vessel that probably sunk during the salerno landing operations of the allied forces in the second world war resistivity data provide information on the vertical and horizontal extension of the shipwreck which is characterized by very low calculated resistivity values about 2 5 ohm m such values differ significantly from the sand and the bedrock values 5 40 ohm m although the presence of the shipwreck is clearly visible from geoelectric data the joint application of electric magnetic and multibeam bathymetric techniques reduces the ambiguities inherent in each method as shown in the electrical resistivity tomography ert and confirmed by the digital elevation model obtained from the processing of bathymetric data the shipwreck extends more than 30 m in ne sw direction and it is about 13 m wide the global extension of the relic is consistent with the magnetic data that are characterized by a magnetic anomaly with an amplitude of about 1800 nt and similar dimension as inferred from the estimation of source boundaries obtained from the computation of the analytic signal the results of our survey encourage the use of marine geoelectrical methods for the detection of buried archaeological targets particularly in locations where the use of seismic prospecting is not effective e g very shallow water with sandy sea bottoms the integration of different geophysical methods allows to better define the extension depth and thickness of buried objects suggesting that such an approach is the most effective for underwater archaeological investigations

abrupt cooling of antarctic surface waters and sea ice expansion in the south atlantic sector of the southern ocean at 5000 cal yr b p antarctic surface waters were warm and ice free between 10 000 and 5000 cal yr b p as judged from ice rafted debris and microfossils in a piston core at 53 s in the south atlantic this evidence shows that about 5000 cal yr b p sea surface temperatures cooled sea ice advanced and the delivery of ice rafted detritus ird to the subantarctic south atlantic increased abruptly these changes mark the end of the hypsithermal and onset of neoglacial conditions they coincide with an early neoglacial advance of mountain glaciers in south america and new zealand between 5400 and 4900 cal yr b p rapid middle holocene climate changes inferred from the taylor dome ice core antarctica cooling and increased ird in the north atlantic and the end of the african humid period the near synchrony and abruptness of all these climate changes suggest links among the tropics and both poles that involved nonlinear response to gradual changes in northern hemisphere insolation sea ice expansion in the southern ocean may have provided positive feedback that hastened the end of the hypsithermal and african humid periods in the middle holocene

volcanic plume thermal radiation 1972 eruption of piton de la fournaise reunion island abstract using an infrared radiometer the authors measured the infrared radiation emitted by the plume during the 1972 piton de la fournaise reunion island eruption in the 9 1 to 11 9 m range eight histograms summarize twenty hours of continuous measurements and show a flux between 0 557 and 1 279 w cm 2 with an average of 0 88 w cm 2 the greatest number of events correspond to the flux emitted by lava fountains while the high and rare flux values 4 6 w cm 2 correspond to detonations of chemical explosions probably of h 2 and o 2 after calibration in the laboratory on a reference black body and in the field by correlation with field observations such a technique can be used to follow changes of volcanic activity in remote and dangerous spots information on the number of explosions their magnitude and the presence and relative significance of hot magma can be transmitted continuously to a safe place

identification of preserved fatty acids in archaeological floor sediments from prehistoric sites at ban non wat and nong hua raet in northeast thailand using gas chromatography abstract this paper presents the first record of fatty acids recovered from archaeological sediment samples in southeast asia fatty acid analysis in archaeology provides a good source of evidence for the identification and interpretation of prehistoric dietary patterns by identifying organic remains of animal and plant foods prehistoric hard floor sediment samples excavated from prehistoric sites of ban non wat and nong hua raet located in the upper catchment of the mun river valley in thailand were analysed for this study the samples are from compressed sediment features identified during excavation as floors and interpreted as some form of living or working surfaces dated to the iron age and neolithic periods around 2000 bc ad 500 triglycerides were extracted in hexane derivatized to fatty acid methyl esters and analysed using gas chromatography flame ionization detector and gas chromatography mass spectrometry twenty fatty acids including saturated and unsaturated counterparts were identified in the hard floor sediments comparison with control samples indicate that the floor samples have distinctive fatty acid assemblages interpreted to relate to the anthropogenic activity associated with the formation of the floors results suggest that many of the fatty acids are mainly of degraded animal origin possibly from ruminants including cow and deer

deep sea coral evidence for rapid change in ventilation of the deep north atlantic 15 400 years ago coupled radiocarbon and thorium 230 dates from benthic coral species reveal that the ventilation rate of the north atlantic upper deep water varied greatly during the last deglaciation radiocarbon ages in several corals of the same age 15 41 0 17 thousand years and nearly the same depth 1800 meters in the western north atlantic ocean increased by as much as 670 years during the 30 to 160 year life spans of the samples cadmium calcium ratios in one coral imply that the nutrient content of these deep waters also increased our data show that the deep ocean changed on decadal centennial time scales during rapid changes in the surface ocean and the atmosphere

magnitude and geographic variation of the radiocarbon content in antarctic marine life implications for reservoir corrections in radiocarbon dating abstract radiocarbon age estimates on marine derined materials from the antarctic appear old in comparison with the terrestrial radiocarbon timescale as a result of significantly depleted 14 c concentrations in antarctic seas we review measurements of 14 c concentrations in modern antarctic marine life from south georgia the shetland islands and antarctic peninsula and suggest correction factors required to relate radiocarbon measurements on fossil marine materials from these areas to the conventional radiocarbon timescale for dates based on shells seaweeds sealbones and penguin bones the minimum correction factor for south georgia is ca 750 years and for the south shetland islands and antarctic peninsula it may be up to 1250 1300 years for whalebones a minimum correction of 1000 years may apply over a wide geographic area for comparison we also review radiocarbon measurements on marine species and seawater from other sectors of the antarctic in high latitudes correction factors of ca 1400 years are generally applicable to shell seal and penguin samples

rapid least squares inversion of apparent resistivity pseudosections by a quasi newton method1 a fast inversion technique for the interpretation of data from resistivity tomography surveys has been developed for operation on a microcomputer this technique is based on the smoothness constrained least squares method and it produces a two dimensional subsurface model from the apparent resistivity pseudosection in the first iteration a homogeneous earth model is used as the starting model for which the apparent resistivity partial derivative values can be calculated analytically for subsequent iterations a quasi newton method is used to estimate the partial derivatives which reduces the computer time and memory space required by about eight and twelve times respectively compared to the conventional least squares method tests with a variety of computer models and data from field surveys show that this technique is insensitive to random noise and converges rapidly this technique takes about one minute to invert a single data set on an 80486dx microcomputer

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

holocene periodicity in north atlantic climate and deep ocean flow south of iceland climate fluctuations during the past millennium are relatively well documented1 on a longer timescale there is growing evidence of millennial scale variability of holocene climate at periodicities of 2 500 and 950 years possibly caused by changes in solar flux 2 3 and 1 500 years maybe related to an internal oscillation of the climate system 4 5 6 but the involvement of deep water masses in these holocene climate changes has yet to be established here we use sediment grain size data from the iceland basin to reconstruct past changes in the speed of deep water flow the study site is under the influence of iceland scotland overflow water isow the flow of which is an important component of the thermohaline circulation that modulates european climate flow changes coincide with some known climate events the little ice age and the mediaeval warm period and extend over the entire holocene epoch with aquasi periodicity of 1 500 years the grain size data indicate afaster isow flow when the climate of northern europe is warmer however a second mode of operation is observed in the early holocene when warm climate intervals are associated with slower isow flow at that time the melting remnant of land based glacial age ice may have provided a sufficient source of fresh water to the ocean to reduce isow flow south of iceland

practical techniques for 3d resistivity surveys and data inversion1 techniques to reduce the time needed to carry out 3d resistivity surveys with a moderate number 25 to 100 of electrodes and the computing time required to interpret the data have been developed the electrodes in a 3d survey are normally arranged in a square grid and the pole pole array is used to make the potential measurements the number of measurements required can be reduced to about one third of the maximum possible number without seriously degrading the resolution of the resulting inversion model by making measurements along the horizontal vertical and 45 diagonal rows of electrodes passing through the current electrode the smoothness constrained least squares inversion method is used for the data interpretation the computing time required by this technique can be greatly reduced by using a homogeneous half space as the starting model so that the jacobian matrix of partial derivatives can be calculated analytically a quasi newton updating method is then used to estimate the partial derivatives for subsequent iterations this inversion technique has been tested on synthetic and field data where a satisfactory model is obtained using a modest amount of computer time on an 80486dx2 66 microcomputer it takes about 20 minutes to invert the data from a 7 by 7 electrode survey grid using the techniques described below 3d resistivity surveys and data inversion can be carried out using commercially available field equipment and an inexpensive microcomputer

electric and magnetic tomographic approach for the geophysical investigation of an unexplored area in the archaeological site of pompeii southern italy the joint application of electric and magnetic techniques for near surface exploration represents a very useful tool for archaeological investigation and can provide a quantitative contribution to describe the spatial distribution of buried objects in this work we show a new advanced tomographic approach based on the parallel inversion of magnetic and electric observed data aimed at the reconstruction of the subsoil of a still unexplored area of the archaeological site of pompeii southern italy the survey was performed in collaboration with pompeii s archaeological commission the comparison between the results obtained from the tomographic inversions of both electrical and magnetic data was carried out in terms of the data inversions which allowed us to obtain information about the location of the buried geophysical sources in the investigated subsoil the results obtained seem to be in a good agreement both for the position of the geophysical sources and for their dimensions

pre bomb radiocarbon and the reservoir correction for calcareous marine species in the southern ocean four antarctic marine mollusc shells which were collected alive between 1917 and 1940 were analyzed by accelerator mass spectrometry to provide the first pre bomb radiocarbon measurements of biogenic carbonates from the southern ocean after correcting for the impact of fossil fuel combustion suess effect radiocarbon activities of the pre bomb shells averaged 149 8 10 4 in contrast the 14c values for post bomb molluscs echinoderms brachiopods and foraminifera averaged 96 1 25 2 these biogenic carbonate 14c values are nearly identical to pre bomb estimates 148 to 152 and post bomb measurements 98 4 22 0 of the surface waters in the southern ocean average radiocarbon ages of the biogenic carbonates before and after 1950 1303 84 years and 811 205 years respectively along with those from seals and penguins indicate that the antarctic marine radiocarbon reservoir has decreased in age by nearly 500 years during the second half of the 20th century marine species and seawater measurements firmly place the radiocarbon reservoir correction at 1300 100 years for calcareous marine fossils which are widespread abundant and well preserved organic materials for interpreting ice sheet climate and sea level impacts on the antarctic marine ecosystem during the holocene

quaternary surface water temperature estimations calibration of a diatom transfer function for the southern ocean the quantitative diatom analysis of 218 surface sediment samples recovered in the atlantic and western indian sector of the southern ocean is used to define a base of reference data for paleotemperature estimations from diatom assemblages using the imbrie and kipp transfer function method the criteria which justify the exclusion of samples and species out of the raw data set in order to define a reference database are outlined and discussed sensitivity tests with eight data sets were achieved evaluating the effects of overall dominance of single species different methods of species abundance ranking and no analog conditions e g eucampia antarctica on the estimated paleotemperatures the defined transfer functions were applied on a sediment core from the northern antarctic zone overall dominance of fragilariopsis kerguelensis in the diatom assemblages resulted in a close affinity between paleotemperature curve and relative abundance pattern of this species downcore logarithmic conversion of counting data applied with other ranking methods in order to compensate the dominance of f kerguelensis revealed the best statistical results a reliable diatom transfer function for future paleotemperature estimations is presented

the distribution of bomb radiocarbon in the ocean water column inventories are calculated for bomb radiocarbon at all the stations occupied during the geosecs and norpax expeditions and for the available tto stations the pattern of global inventories obtained in this way suggests that a sizable portion of the bomb radiocarbon that entered the antarctic the northern pacific and the tropical ocean has been transported to the adjacent temperate zones a strategy for utilizing these inventory anomalies as constraints on global ocean circulation models is presented essential to this strategy are the improvement of our knowledge of the pattern of wind speed over the ocean the establishment of the wind speed dependence of the rate of gas exchange between the atmosphere and sea and the continued mapping of the distribution of bomb produced radiocarbon in the sea

differenciation de l emanation magmatique reactions h2s so2 dans les gaz volcaniques vulcano italie 1923 1979 differents systemes de prelevements de gaz on ete testes a vulcano italie l echantillonnage en ampoules ne conserve pas le rapport h2s so2 en equilibre a la temperature du prelevement

impact of the ad 79 explosive eruption on pompeii i relations amongst the depositional mechanisms of the pyroclastic products the framework of the buildings and the associated destructive events abstract a quantitative and qualitative evaluation of the damage caused by the products of explosive eruptions to buildings provides an excellent contribution to the understanding of the various eruptive processes during such dramatic events to this end the impact of the products of the two main phases pumice fallout and pyroclastic density currents of the vesuvius ad 79 explosive eruption onto the pompeii buildings has been evaluated based on different sources of data such as photographs and documents referring to the archaeological excavations of pompeii the stratigraphy of the pyroclastic deposits and in situ inspection of the damage suffered by the buildings the present study has enabled the reconstruction of the events that occurred inside the city when the eruption was in progress in particular we present new data related to the c j polibius house a large building located inside pompeii from a comparison of all of the above data sets it has been possible to reconstruct in considerable detail the stratigraphy of the pyroclastic deposits accumulated in the city to understand the direction of collapse of the destroyed walls and to evaluate the stratigraphic level at which the walls collapsed finally the distribution and style of the damage allow us to discuss how the emplacement mechanisms of the pyroclastic currents are influenced by their interaction with the urban centre all the data suggest that both structure and shape of the town buildings affected the transport and deposition of the erupted products for instance sloping roofs drained a huge amount of fall pumice into the impluvia a rectangular basin in the centre of the hall with the function to collect the rain water coming from a hole in the centre of the roof thus producing anomalous deposit thicknesses on the other hand flat and low sloping roofs collapsed under the weight of the pyroclastic material produced during the first phase of the eruption pumice fall in addition it is evident that the walls that happened to be parallel to the direction of the pyroclastic density currents produced during the second eruptive phase were minimally damaged in comparison to those walls oriented perpendicular to the flow direction we suggest that the lower depositional parts of the pyroclastic currents were partially blocked locally reflected and slowed down because of recurring encounters with the closely spaced walls within buildings locally the percentage of demolished walls decreases down current which has been interpreted as a loss in kinetic energy within the depositional system of the flow however it seems that the upper transport system by passed these obstacles then supplied new pyroclasts to the depositional system that restored its physical characteristics and restored enough kinetic energy to demolish the next walls and buildings further along its path

the reconstruction of late quaternary antarctic sea ice distribution the use of diatoms as a proxy for sea ice the study of annual diatom transfer from the southern ocean surface to the sea floor using time series sediment traps combined with the mapping of diatom assemblages from surface sediments results in the definition of a proxy for past variations of sea ice extent the application and robustness of the proposed proxy are demonstrated by the study of late pleistocene sediment cores recovered from different environmental regimes in the southern ocean relative amounts of the sea ice indicator diatoms fragilariopsis cylindrus and fragilariopsis curta of 3 in diatom assemblages preserved in sediments are representative of the presence of seasonal winter sea ice summer sea ice occurrence is signalled by a distinct drop in biogenic sedimentation rate as a result of strongly reduced biogenic export in the presence 3 of diatom assemblage of the deep temperature diatom fragilariopsis obliquecostata the spatial and temporal distribution pattern of the sea ice proxy indicates significant sea ice variations during marine isotope stages 1 and 5 in the present antarctic zone of the southern ocean during glacial maxima the antarctic winter sea ice was extended into the present polar front zone while the antarctic summer sea ice was most probably expanded into the area of the present winter sea ice edge during the short climatic optima at the onset of interglacial periods the winter sea ice extent was distinctly reduced

volcanic gas emissions from soufriere hills volcano montserrat 1995 2009 with implications for mafic magma supply and degassing volcanic gas emissions illustrate a complex volatile budget for soufriere hills volcano montserrat fluxes of sulphur dioxide carbon dioxide hydrogen sulphide and hydrogen chloride and probably water are substantial from this arc volcano additional sources of volatiles in addition to the erupting andesite are required to satisfy the mass balance defined by gas emissions and petrological constraints mafic magma is intruded at depths of 10 km supplying volatiles by quenching crystallising and vesiculating at the andesite mafic magma interface sulphur carbon dioxide and other volatiles supplied to the system migrate to the surface and their fluxes remain high while mafic recharge at depth is sustained decompression degassing of porphyritic andesite supplies chlorine and water to the gas plume chlorine partitions into vapour from the melt during periods of active extrusion making the hcl so2 ratio of volcanic gases a reliable indicator of the onset of eruptive activity studies of this volatile budget highlight the role of deep degassing and vapour production at arc volcanoes which are important mechanisms for driving the eruption due to its effects on magma buoyancy and the advection of heat through the system

226ra in barite absolute dating of holocene southern ocean sediments and reconstruction of sea surface reservoir ages absolute dating of marine sediments is necessary to achieve reliable correlations of paleoclimate records the 2 2 6 ra decay in barite separated from a deep sea core of the southern ocean was used to determine absolute ages for the holocene epoch comparison with 1 4 c ages measured on planktic foraminifers provides the first past sea surface reservoir ages in the antarctic zone of the southern ocean throughout the middle to late holocene our results indicate a reservoir age of ca 1100 yr comparable to modern estimates a significantly higher reservoir age ca 1900 yr is obtained for the early holocene which suggests a major change in the southern ocean circulation at that time