http://hdl.handle.net/2122/185 Wed, 22 May 2013 09:22:12 GMT 2013-05-22T09:22:12Z http://hdl.handle.net/2122/7740 Title: Isotopic evidence for open system processes within the Campanian Ignimbrite (Campi Flegrei-Italy) magma chamber Authors: Arienzo, I.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Civetta, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia; Heumann, A.; GZG, Abt. Geochemie, Georg August Universitat; Worner, G.; GZG, Abt. Geochemie, Georg August Universitat; Orsi, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione OV, Napoli, Italia Abstract: Abstract New Sr and Nd isotope data for whole rocks, glasses and minerals are combined to reconstruct the nature and origin of mixing end-members of the 200 km3 trachytic to phonolitic Campanian Ignimbrite (Campi Flegrei, Italy) magmatic system. The least-evolved magmatic end-member shows equilibrium between host glass and the majority of the phenocrysts and is less radiogenic in Sr and Nd than the most-evolved magma. On the contrary, only the Fe-rich pyroxene from the most-evolved erupted magma is in equilibrium with the matrix glass, while all other minerals are in isotopic disequilibrium. These magmas mixed prior to and during the Campanian Ignimbrite eruption and minerals were freely exchanged between the magma batches. Combining the results of the geochemical investigations on magma end-members with geophysical and geological data, we develop the following scenario. In stage 1, a parental, less differentiated magma rose into the middle crust, and evolved through combined crustal assimilation and crystal fractionation. In stage 2, the differentiated magma rose to shallower depth, fed the pre-Campanian Ignimbrite activity and evolved by further open-system processes into the most-evolved and most-radiogenic Campanian Ignimbrite end-member magma. In stage 3, new trachytic magma, isotopically distinct from the pre-Campanian Ignimbrite magmas, rose from ca. 6 km to shallower depth, recharged the most-evolved pre-Campanian Ignimbrite magma chamber, and formed the large and stratified Campanian Ignimbrite magmatic system. During the course of the Campanian Ignimbrite eruption, the two layers were tapped separately and/or simultaneously, and gave rise to the range of chemical and isotopic values displayed by the Campanian Ignimbrite pumices, glasses and minerals. Tue, 01 Jul 2008 22:00:00 GMT http://hdl.handle.net/2122/7740 2008-07-01T22:00:00Z http://hdl.handle.net/2122/7472 Title: Geochemistry of groundwater from Graciosa Island (Azores): A contribution to the hydrothermal system conceptual model Authors: Carvalho, M.R.; 1Universidade de Lisboa, Faculdade de Ciencias, Depart. Geologia/CeGUL, Portugal; Carreira, P.; Instituto Tecnologico e Nuclear, Lisboa, Portugal; Marques, J.M.; Instituto Superior Tecnico, Lisboa, Portugal; Capasso, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia; Grassa, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia; Nunes, J.C.; Universidade dos Açores & INOVA Inst., Azores, Portugal Abstract: Graciosa island is located in the Azores Archipelago, along the so-called Terceira Rift, a major tectonic structure that makes the NE boundary of the Azores Plateau. In general terms, it includes a basaltic plataform on the NW and a silicic poligenetic volcano with caldera on the SE, the Graciosa Caldera Volcano. This volcano has produced significant tephra falls, pyroclastic flows, lahars, and lava flows, both of basaltic s.l. and trachitic s.l. composition. The hydrothermal system shows fumarolic emissions inside the volcano caldera and thermal springs located along the shoreline. This system is exploitated in a thermal building through shallow and deep (110 m) boreholes, near the coast. In Graciosa two types of Na-Cl groundwater systems can be identified: 1) a cold one emerging at springs and exploited by wells for public water supply, and 2) a hydrothermal system with temperatures around 40-44 °C. The cold groundwaters have pH higher than 7 and different degree of mineralization, according to the proximity to the sea. The thermal waters show mixing with seawater, pH varying between 6.20 and 6.94, 166 mg/L of SiO2, and significant concentration of metals, such as Mn, Fe, Co, Ni, Cu and Zn. The thermal water mineralization varies strongly, showing EC from 8.87 mS/cm (shallow water) to 47.4 mS/cm (deeper water). The higher mineralized water is rich in CO2(g), with 2130 mg/L of total dissolved CO2. Geothermometers application reveals aquifer temperature around 167 °C and immature/mixed waters, not reaching complete equilibrium with reservoir rock. The geochemistry of the thermal waters indicates the occurrence of seawater/host rock interaction processes at high temperature and slightly acid conditions, favored by CO2(g) input, and a different degrees of mixing with cold and shallow groundwaters. Sat, 13 Aug 2011 22:00:00 GMT http://hdl.handle.net/2122/7472 2011-08-13T22:00:00Z http://hdl.handle.net/2122/7468 Title: Helium isotopes distribution in NW Iberian peninsula: evidences of a local neotectonic activity Authors: Grassa, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia; Capasso, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia; Carreira, P.; Instituto Tecnológico e Nuclear, Sacavém, Portugal; Carvalho, M.R.; Universidade de Lisboa, Faculdade CienciasDpt. Geologia, Lisboa; Marques, J.M.; Instituto Superior Técnico, Lisboa; Antunes da Silva, M.; UNICER Bebidas, S.A. S. Mamede de Infesta Editors: Demény, Attila; Instute for geochemical research, Hungarian Academy of Sciences Abstract: In this work we report new data on He abundances and isotope ratios (3He/4He) from gas associated to some thermal and CO2-rich mineral waters in N-Portugal. Collected gas samples are mainly CO2-dominant except two sites where gas is N2-rich. All the sampling sites are characterized by exceptionally high helium contents with 3He/4He ratios, corrected for air contamination, varying considerably from 0.09 to 2.68 Ra. In all sites, the 3He/4He ratios are higher than that typical for stable continental areas thus indicating a variable but not-negligible (up to 30%) contribution of mantle-derived primordial He. In all the CO2-rich waters, CO2/3He ratios and 13CCO2 are comparable with mantle values, thus suggesting a magmatic origin also for CO2. On the contrary, in the N2-rich waters He is mainly radiogenic, and CO2 is organic in origin. Since no recent volcanic activity is observed in NW Iberia, high 3He/4He values could be due, at least, to three processes: a) releasing of gas from the local upper mantle through deep extensional fault systems; b) releasing of magmatic volatiles from crustal reservoir(s) formed during past volcanic activity; c) degassing of a subsurface emplaced magma body. Mantle He flux in N-Portugal has been estimated to be up to 3 orders of magnitude higher than that typical for stable continental areas, thus suggesting, in this area, the presence of a tensional tectonic regime. This implies that mantle gases could migrate upward probably through inherited tectonic structures reactivated by neotectonic activity. The third possible scenario seems to be less plausible since seismic surveys carried out in NW Iberian did not find any significant evidence of mantle intrusion in the crust. The observed spatial variability in mantle-derived contribution could reflect the geometry of the granitic plutons in this area, thus supporting the hypotheses of an upper mantle degassing. Alternatively, it could be the result of a lateral migration of magmatic volatiles stored in a crustal reservoir. Wed, 03 Aug 2011 22:00:00 GMT http://hdl.handle.net/2122/7468 2011-08-03T22:00:00Z http://hdl.handle.net/2122/7257 Title: Spatial distribution of soil radon as a tool to recognize active faulting on an active volcano: the example of Mt. Etna (Italy) Authors: Neri, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Giammanco, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Ferrera, E.; Università degli Studi di Catania, Dip. Scienze della Terra, Corso Italia, 52 e 95129 Catania, Italy; Patanè, G.; Università degli Studi di Catania, Dip. Scienze della Terra, Corso Italia, 52 e 95129 Catania, Italy; Zanon, V.; Centro de Vulcanologia e Avaliação de Riscos Geológicos e Universidade dos Açores, Rua Mãe de Deus, 9501-801 Ponta Delgada, Portugal Abstract: This study concerns measurements of radon and thoron emissions from soil carried out in 2004 on the eastern flank of Mt. Etna, in a zone characterized by the presence of numerous seismogenic and aseismic faults. The statistical treatment of the geochemical data allowed recognizing anomaly thresholds for both parameters and producing distribution maps that highlighted a significant spatial correlation between soil gas anomalies and tectonic lineaments. The seismic activity occurring in and around the study area during 2004 was analyzed, producing maps of hypocentral depth and released seismic energy. Both radon and thoron anomalies were located in areas affected by relatively deep (5e10 km depth) seismic activity, while less evident correlation was found between soil gas anomalies and the released seismic energy. This study confirms that mapping the distribution of radon and thoron in soil gas can reveal hidden faults buried by recent soil cover or faults that are not clearly visible at the surface. The correlation between soil gas data and earthquakes depth and intensity can give some hints on the source of gas and/or on fault dynamics. Fri, 24 Jun 2011 22:00:00 GMT http://hdl.handle.net/2122/7257 2011-06-24T22:00:00Z http://hdl.handle.net/2122/7256 Title: Radionuclide measurements, viad ifferent methodologies, as tool for geophysical studies on Mt. Etna Authors: Morelli, D.; Dipartimento diFisicaeAstronomia,Universit a diCatania,viaS.Sofia,64I-95123Catania,Italy; Immè, G.; Dipartimento diFisicaeAstronomia,Universit a diCatania,viaS.Sofia,64I-95123Catania,Italy; Altamore, I.; Dipartimento diFisicaeAstronomia,Universit a diCatania,viaS.Sofia,64I-95123Catania,Italy; Cammisa, S.; Dipartimento diFisicaeAstronomia,Universit a diCatania,viaS.Sofia,64I-95123Catania,Italy; Giammanco, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; La Delfa, S.; Dipartimento diScienzeGeologiche,Universit a diCatania,CorsoItalia,57I-95127Catania,Italy; Mangano, G.; Dipartimento diFisicaeAstronomia,Universit a diCatania,viaS.Sofia,64I-95123Catania,Italy; Neri, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Patanè, G.; Dipartimento diScienzeGeologiche,Universit a diCatania,CorsoItalia,57I-95127Catania,Italy Abstract: Natural radioactivity measurements represent an interesting tool to study geodynamical events or soil geophysical characteristics. In this direction we carried out, in the last years, several radionuclide monitoring both in the volcanic and tectonic areas of the oriental Sicily. In particular we report in-soil Radon investigations, in a tectonic area, including both laboratory and in-site measurements, applying three different methodologies, based on both active and passive detection systems. The active detection devices consisted of solid-state silicon detectors equipped in portable systems for short-time measurements and for long-time monitoring. The passive technique consisted of solid-state nuclear track detectors (SSNTD), CR-39 type, and allowed integrated measurements. The performances of the three methodologies were compared according to different kinds of monitoring. In general the results obtained with the three methodologies seem in agreement with each other and reflect the tectonic settings of the investigated area. Fri, 04 Feb 2011 23:00:00 GMT http://hdl.handle.net/2122/7256 2011-02-04T23:00:00Z http://hdl.handle.net/2122/5290 Title: Radioactivity in waters of Mt. Etna (Italy) Authors: Kozlowska, B.; University of Silesia, Institute of Physics, Department of Nuclear Physics and Its Applications, ul. Uniwersytecka 4, 40007 Katowice, Poland; Morelli, D.; Dipartimento di Fisica e Astronomia, Universita` di Catania, via S. Sofia, 64 I-95123 Catania, Italy; Walencik, A.; University of Silesia, Institute of Physics, Department of Nuclear Physics and Its Applications, ul. Uniwersytecka 4, 40007 Katowice, Poland; Dorda, J.; University of Silesia, Institute of Physics, Department of Nuclear Physics and Its Applications, ul. Uniwersytecka 4, 40007 Katowice, Poland; Altamore, I.; Dipartimento di Fisica e Astronomia, Universita` di Catania, via S. Sofia, 64 I-95123 Catania, Italy; Chieffalo, V.; Dipartimento di Fisica e Astronomia, Universita` di Catania, via S. Sofia, 64 I-95123 Catania, Italy; Giammanco, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Imme, G.; Dipartimento di Fisica e Astronomia, Universita` di Catania, via S. Sofia, 64 I-95123 Catania, Italy; Zipper, W.; University of Silesia, Institute of Physics, Department of Nuclear Physics and Its Applications, ul. Uniwersytecka 4, 40007 Katowice, Poland Abstract: Radioactivity in underground waters from Mt. Etna was investigated on the basis of 13 samples. The samples were collected from springs, wells and galleries around the volcano. Water from nine out of thirteen intakes is used for consumption. Activity concentration of uranium isotopes 234,238U, radium isotopes 226,228Ra and radon 222Rn were determined with the use different nuclear spectrometry techniques. The measurements of radium and radon activity concentration were performed with the use of a liquid scintillation counter. The determination of uranium isotopes was carried out with the use of alpha spectrometry. All samples show uranium concentration above Minimum Detectable Activity (MDA), with the highest total uranium (234U þ 238U) activity concentration equal to 130 mBq/l. For radium isotopes, all samples except one showed the activity concentration below MDA. Radon activity concentration was within the range from 1 to 13 Bq/l, hence these waters can be classified as low-radon waters. Tue, 31 Mar 2009 22:00:00 GMT http://hdl.handle.net/2122/5290 2009-03-31T22:00:00Z http://hdl.handle.net/2122/4912 Title: Comparison between different methodologies for detecting Radon in soil along an active fault: the case of the Pernicana fault system, Mt. Etna (Italy) Authors: Giammanco, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Immè, G.; Dipartimento diFisicaeAstronomia,Universita` degli StudidiCatania,viaS.Sofia,64,95123Catania,Italy; Mangano, G.; Dipartimento diFisicaeAstronomia,Universita` degli StudidiCatania,viaS.Sofia,64,95123Catania,Italy; Morelli, D.; Dipartimento diFisicaeAstronomia,Universita` degli StudidiCatania,viaS.Sofia,64,95123Catania,Italy; Neri, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia Abstract: Three different methodologies were used to measure Radon (222Rn) in soil, based on both passive and active detection system. The first technique consisted of Solid State Nuclear Track Detectors (SSNTD), CR-39 type, and allowed integrated measurements. The second one consisted of a portable device for short time measurements. The last consisted of a continuous measurement device for extended monitoring, placed in selected sites. Soil 222Rn activity was measured together with soil Thoron (220Rn) and soil carbon dioxide (CO2) efflux, and it was compared with the content of radionuclides in the rocks. Two different soil gas horizontal transects were investigated across the Pernicana fault system (NE flank of Mount Etna), from November 2006 to April 2007. The results obtained with the three methodologies are in a general agreement with each other and reflect the tectonic settings of the investigated study area. The lowest 222Rn values were recorded just on the fault plane, and relatively higher values were recorded a few tens of meters from the fault axis on both of its sides. This pattern could be explained as a dilution effect resulting from high rates of soil CO2 efflux. Time variations of 222Rn activity were mostly linked to atmospheric influences, whereas no significant correlation with the volcanic activity was observed. In order to further investigate regional radon distributions, spot measurements were made to identify sites having high Rn emissions that could subsequently be monitored for temporal radon variations.. SSNTD measurements allow for extended-duration monitoring of a relatively large number of sites, although with some loss of temporal resolution due to their long integration time. Continuous monitoring probes are optimal for detailed time monitoring, but because of their expense, they can best be used to complement the information acquired with SSNTD in a network of monitored sites.. Wed, 31 Dec 2008 23:00:00 GMT http://hdl.handle.net/2122/4912 2008-12-31T23:00:00Z http://hdl.handle.net/2122/4139 Title: Comparison between different methodologies for detecting Radon in soil along an active fault: the case of the Pernicana fault system, Mt. Etna (Italy) Authors: Giammanco, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia; Immè, G.; Dipartimento diFisicaeAstronomia,Universita` degli StudidiCatania,viaS.Sofia,64,95123Catania,Italy; Mangano, G.; Dipartimento diFisicaeAstronomia,Universita` degli StudidiCatania,viaS.Sofia,64,95123Catania,Italy; Morelli, D.; Dipartimento diFisicaeAstronomia,Universita` degli StudidiCatania,viaS.Sofia,64,95123Catania,Italy; Neri, M.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Catania, Catania, Italia Abstract: Three different methodologies were used to measure Radon (222Rn) in soil, based on both passive and active detection system. The first technique consisted of Solid State Nuclear Track Detectors (SSNTD), CR-39 type, and allowed integrated measurements. The second one consisted of a portable device for short time measurements. The last consisted of a continuous measurement device for extended monitoring, placed in selected sites. Soil 222Rn activity was measured together with soil Thoron (220Rn) and soil carbon dioxide (CO2) efflux, and it was compared with the content of radionuclides in the rocks. Two different soil gas horizontal transects were investigated across the Pernicana fault system (NE flank of Mount Etna), from November 2006 to April 2007. The results obtained with the three methodologies are in a general agreement with each other and reflect the tectonic settings of the investigated study area. The lowest 222Rn values were recorded just on the fault plane, and relatively higher values were recorded a few tens of meters from the fault axis on both of its sides. This pattern could be explained as a dilution effect resulting from high rates of soil CO2 efflux. Time variations of 222Rn activity were mostly linked to atmospheric influences, whereas no significant correlation with the volcanic activity was observed. In order to further investigate regional radon distributions, spot measurements were made to identify sites having high Rn emissions that could subsequently be monitored for temporal radon variations.. SSNTD measurements allow for extended-duration monitoring of a relatively large number of sites, although with some loss of temporal resolution due to their long integration time. Continuous monitoring probes are optimal for detailed time monitoring, but because of their expense, they can best be used to complement the information acquired with SSNTD in a network of monitored sites. Mon, 31 Dec 2007 23:00:00 GMT http://hdl.handle.net/2122/4139 2007-12-31T23:00:00Z http://hdl.handle.net/2122/2724 Title: Fluid geochemistry investigations on the volcanic system of methana Authors: D'Alessandro, W.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia; Brusca, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia; Kyriakopoulos, K.; University of Athens; Margaritopoulos, M.; University of Athens; Michas, G.; University of Athens; Papadakis, G.; University of Athens Abstract: An extensive geochemical survey on the fluids released by the volcanic/geothermal system of Methana was undertaken. Characterization of the gases was made on the basis of the chemical and isotopic (He and C) analysis of 14 samples. CO2 soil gas concentration and fluxes were measured on the whole peninsula at more than 100 sampling sites. 31 samples of thermal and cold groundwaters were also sampled and analysed to characterize the geochemistry of aquifers. Anomalies referable to the geothermal system, besides at known thermal manifesta-tions, were also recognized at some anomalous degassing soil site and in some cold groundwater. These anomalies were always spatially correlated to the main active tectonic system of the area. The total CO2 output of the volcanic system has been preliminary estimated in about 0.2 kg s-1. Although this value is low compared to other volcanic systems, anomalous CO2 degassing at Methana may pose gas hazard problems. Such volcanic risk, although restricted to limited areas, cannot be neglected and further studies have to be undertaken for its better assessment Mon, 30 Apr 2007 22:00:00 GMT http://hdl.handle.net/2122/2724 2007-04-30T22:00:00Z http://hdl.handle.net/2122/2481 Title: Chemical and isotopic composition of waters and dissolved gases in some thermal springs of sicily and adjacent volcanic islands, Italy. Authors: Grassa, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia; Capasso, G.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia; Favara, R.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia; Inguaggiato, S.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Palermo, Palermo, Italia Abstract: Hydrochemical (major and some minor constituents), stable isotope (dDH2O and d18OH2O; d13CTDIC total dissolved inorganic carbon) and dissolved gas composition have been determined on 33 thermal discharges located throughout Sicily (Italy) and its adjacent islands. On the basis of major ion contents, four main water types have been distinguished: (1) a Na-Cl type; (2) a Ca-Mg>Na- SO4-Cl type; (3) a Ca-Mg-HCO3 type and (4) a Na-HCO3 type water. Most waters are meteoric in origin or resulting from mixing between meteoric water and heavy-isotope end members. In some samples, d18O values reflect the effects of equilibrium processes between thermal waters and rocks (positive 18O-shift) or thermal waters and CO2 (negative 18O-shift). Dissolved gas composition indicates the occurrence of gas/ water interaction processes in thermal aquifers. N2/O2 ratios higher than air-saturated water (ASW), suggest the presence of geochemical processes responsible for dissolved oxygen consumption. High CO2 contents (more than 3000 cc/litre STP) dissolved in the thermal waters indicate the presence of an external source of carbon dioxide-rich gas. TDIC content and d13CTDIC show very large ranges from 4.6 to 145.3 mmol/Kg and from )10.0& and 2.8&, respectively. Calculated values indicate the significant contribution from a deep source of carbon dioxide inorganic in origin. Interaction with Mediterranean magmatic CO2 characterized by heavier carbon isotope ratios (d13CCO2 value from )3 to 0& vs V-PDB (CAPASSO et al., 1997, GIAMMANCO et al., 1998; INGUAGGIATO et al., 2000) with respect to MORB value and/ or input of CO2-derived from thermal decomposition of marine carbonates have been inferred. Sat, 31 Dec 2005 23:00:00 GMT http://hdl.handle.net/2122/2481 2005-12-31T23:00:00Z