Understanding magma evolution at Campi Flegrei (Campania, Italy) volcanic complex using melt inclusions and phase equilibria     

Claudia Cannatelli 《Mineralogy and Petrology》2012,104(1-2):29-42

The magmatic evolution of two eruptive episodes at Campi Flegrei (Italy) has been investigated using phase equilibria modeling (MELTS) and data from melt inclusions (MIs) in phenocrysts from the Fondo Riccio and Minopoli 1 eruptions. Assuming that isobaric fractional crystallization of a mantle-derived parental magma is the dominant petrogenetic process, major element evolution and corresponding changes in the physical and thermodynamic properties of the magma bodies from which Fondo Riccio and Minopoli1 magmas were erupted can be tracked. Fondo Riccio parental magma was trachyandesitic, approximated by the composition of FR-C1-O2-M1, which evolved mainly through fractional crystallization at low pressure (P?≈?0.15?GPa, ≈ 7?km depth), along the QFM, QFM?+?1 oxygen buffer with an initial dissolved H₂O content of ～3?wt%. Minopoli1 parental magma was trachyandesitic, approximated by the chemistry of Mi1-C1-O5-M1, evolved through fractional crystallization at P?≈?0.3?GPa (≈ 12?km depth), with oxygen fugacity along QFM?+?1buffer and initial H₂O content of?～?2 wt%. The relationship between melt fraction and T reveals for Fondo Riccio the presence of a pseudo-invariant temperature at which the physical properties of melt change abruptly. The net effect of these changes is to drive the system towards dynamic instability, which it is suggested to be the trigger mechanism for the eruptions.  相似文献   

Thermal behavior of almandine at temperatures up to 1,200°C in hydrogen     

Claudia?Aparicio  Jan?FilipEmail author  Henrik?Skogby  Zdenek?Marusak  Miroslav?Mashlan  Radek?Zboril 《Physics and Chemistry of Minerals》2012,39(4):311-318

The thermally induced reductive decomposition of a natural near end-member almandine [^VIII(Fe_2.85Mg_0.11Ca_0.05Mn_0.02)^VI(Al_1.99)^IV(Si_2.99)O₁₂] and possible hydrogen diffusion into its structure have been carried out at temperatures up to 1,200°C, monitored by simultaneous thermogravimetric analysis and differential scanning calorimetry (DSC), infrared and ⁵⁷Fe Mössbauer spectroscopy and X-ray powder diffraction. Below 1,000°C, evidence for hydrogen diffusion into almandine structure was not observed. At temperatures above 1,000°C, reductive decomposition sets in, as displayed by a sharp endothermic peak at 1,055°C on the DSC curve accompanied by a total mass loss of 3.51%. We observe the following decomposition mechanism: almandine + hydrogen → α-Fe + cristobalite + hercynite + water. At higher temperatures, fayalite and sekaninaite are formed by consecutive reaction of α-Fe with cristobalite and water, and cristobalite with hercynite, respectively. The metallic α-Fe phase forms spherical and isolated particles (~1 μm).  相似文献   

Seasonal changes in organotin compounds in sediments from the Bahía Blanca Estuary     

Pamela Y. Quintas  Ana L. Oliva  Andrés Arias  Claudia E. Domini  Mónica B. Alvarez  Mariano Garrido  Jorge E. Marcovecchio 《Environmental Earth Sciences》2016,75(8):659

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Potentially harmful elements and lead isotopes distribution in a heavily anthropized suburban area: the Casoria case study (Italy)     

Diego Civitillo  Robert A. Ayuso  Annamaria Lima  Stefano Albanese  Rosario Esposito  Claudia Cannatelli  Benedetto De Vivo 《Environmental Earth Sciences》2016,75(19):1325

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A BPR approach to hydrogeological risk management     

Maurizio Bevilacqua  Filippo Emanuele Ciarapica  Claudia Paciarotti 《Natural Hazards》2014,71(3):1995-2012

Every year, landslides and floods cause deaths, missing persons, injured people, evacuees, and homeless people. Serious damages to property and pollution are also produced. Lessons learn from landslides and flood disasters recently occurred show that flood and disaster management should be widely improved. This paper deals the problem of hydrogeological risk management from a logistic and a managerial point of view. The hydrological risk management is studied as an industrial process, and it is modeled by the IDEF0 language. The IDEF0 application provides a clear overview of the system and became a structured base for the re-engineering process. For each function of the process, the inputs, outputs, and necessary controls and resources have been identified. The use of the IDEF0 provides a simple and effective tool for the decision-making process. Starting from a realistic and efficient current state model, the process of re-engineering has been implemented. The main aim of the change introduced in the process is to improve the information management that it is a crucial point of the risk management.  相似文献   

Landslide triggers along volcanic rock slopes in eastern Sicily (Italy)   总被引：3，自引：0，他引：3  

Maria Serafina Barbano  Giovanna Pappalardo  Claudia Pirrotta  Simone Mineo 《Natural Hazards》2014,73(3):1587-1607

A new dataset of landslides, occurred in a tectonically active region, has been analysed in order to understand the causes of the slope instability. The landslides we have dealt with took place along the volcanic rock cliff of S. Caterina and S. Maria La Scala villages (eastern Sicily, Italy), a densely inhabited area located on the eastern margin of Mt. Etna, where some seismogenic faults, locally named Timpe system, slip during moderate local earthquakes and also move with aseismic creep mechanisms. The results show that landslides are triggered by heavy rainfalls, earthquakes and creep fault episodes. Indeed, they occur along discrete fault segments, exhibiting a combination of both brittle failure, indicated by the earthquake occurrence, and aseismic creep events. The analysis of seismicity occurred on the Timpe fault system has shown that the active Acireale fault, in its southernmost segment, is subject to an aseismic sliding, which increases after the stick–slip motion in the nearby faults. Therefore, aseismic creep seems to concur in the predisposition of a rock to fail, since strains can increase the jointing of rock masses leading to a modification in the slope stability. Understanding the factors concurring to the slope instability is a useful tool for future assessments of the landslide hazard in densely settled areas, located on a volcanic edifice, such as Etna that is slowly sliding seawards, and where active faults, seismicity and heavy rains affect the deeply fractured slopes.  相似文献   

Comparative study of geophysical and soil–gas investigations at the Hartoušov (Czech Republic) natural CO2 degassing site     

Claudia Sandig  Uta Sauer  Karin Bräuer  Ulrich Serfling  Claudia Schütze 《Environmental Earth Sciences》2014,72(5):1421-1434

Our study at this natural analog site contributes to the evaluation of methods within a hierarchical monitoring concept suited for the control of CO₂ degassing. It supports the development of an effective monitoring concept for geological CO₂ storage sites—carbon capture and storage as one of the pillars of the European climate change efforts. This study presents results of comprehensive investigations along a 500-m long profile within the Hartou?ov (Czech Republic) natural CO₂ degassing site and gives structural information about the subsurface and interaction processes in relation to parameters measured. Measurements of CO₂ concentrations and investigation of the subsurface using electrical resistivity tomography and self-potential methods provide information about subsurface properties. For their successful application it is necessary to take seasonal variations (e.g., soil moisture, temperature, meteorological conditions) into consideration due to their influence on these parameters. Locations of high CO₂ concentration in shallow depths are related to positive self-potential anomalies, low soil moistures and high resistivity distributions, as well as high δ13C values and increased radon concentrations. CO₂ ascends from deep geological sources via preferential pathways and accumulates in coarser sediments. Repetition of measurements (which includes the effects of seasonal variations) revealed similar trends and allows us to identify a clear, prominent zone of anomalous values. Coarser unconsolidated sedimentary layers are beneficial for the accumulation of CO₂ gas. The distribution of such shallow geological structures needs to be considered as a significant environmental risk potential whenever sudden degassing of large gas volumes occurs.  相似文献   

The role of carbonate ions in pyrite oxidation in aqueous systems     

Claudia L. Caldeira  Virginia S.T. Ciminelli  Kwadwo Osseo-Asare 《Geochimica et cosmochimica acta》2010,74(6):1777-1789

The mechanism of pyrite oxidation in carbonate-containing alkaline solutions at 80 °C was investigated with the help of rate experiments, thermodynamic modeling and diffuse reflectance infrared spectroscopy (DRIFTS). Pyrite oxidation rate increased with pH and was enhanced by addition of bicarbonate/carbonate ions. The carbonate effect was found to be limited to moderately alkaline conditions (pH 8-11). Metastable Eh-pH diagrams, at 25 °C, indicate that soluble iron-carbonate complexes (FeHCO₃⁻, FeCO₃⁰, Fe(CO₃)(OH)⁻ and FeCO₃²⁻) may coexist with pyrite in the pH range of 6-12.5. Above pH 11 and 13, the Fe(II) and Fe(III) hydroxocomplexes, respectively, become stable, even in the presence of carbonate/bicarbonate ions. Surface-bound carbonate complexes on iron were also identified with DRIFTS as products of pyrite oxidation in addition to iron oxyhydroxides and soluble sulfate species. The conditions under which thermodynamic and DRIFTS analyses indicate the presence of carbonate compounds also correspond to those in which the fastest rate of pyrite oxidation in carbonate solutions was observed. Following the Singer-Stumm model for pyrite oxidation in acidic solutions, it is assumed that Fe(III) is the preferred pyrite oxidant under alkaline conditions. We propose that carbonate ions facilitate the electron transfer from soluble iron(II)-carbonate to O₂, increase the iron solubility, and provide buffered, favorable alkaline conditions at the reaction front, which in turn favors the overall kinetics of pyrite oxidation. Therefore, the electron transfer from sulfur atoms to O₂ is facilitated by the formation of the cycle of Fe(II)-pyrite/Fe(III)-carbonate redox couple at the pyrite surface.  相似文献   

Estimation of hydraulic parameters in a heterogeneous low-lying farmland near Venice     

Ester Zancanaro  Claudia Zoccarato  Francesco Morari  Pietro Teatini 《水文研究》2023,37(1):e14791

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Twinned calcite as an indicator of high differential stresses and low shock pressure conditions during impact cratering     

Lina Seybold  Claudia A. Trepmann  Stefan Hölzl  Kilian Pollok  Falko Langenhorst  Fabian Dellefant  Melanie Kaliwoda 《Meteoritics & planetary science》2023,58(9):1287-1305

Shock-related calcite twins are characterized in calcite-bearing metagranite cataclasites within crystalline megablocks of the Ries impact structure, Germany, as well as in cores from the FBN1973 research drilling. The calcite likely originates from pre-impact veins within the Variscan metagranites and gneisses, while the cataclasis is due to the Miocene impact. Quartz in the metagranite components does not contain planar deformation features, indicating low shock pressures (<7 GPa). Calcite, however, shows a high density (>1/μm) of twins with widths <100 nm. Different types of twins (e-, f-, and r-twins) crosscutting each other can occur in one grain. Interaction of r- and f-twins results in a-type domains characterized by a misorientation relative to the host with a misorientation angle of 35°–40° and a misorientation axis parallel to an a-axis. Such a-type domains have not been recorded from deformed rocks in nature before. The high twin density and activation of different twin systems in one grain require high differential stresses (on the order of 1 GPa). Twinning of calcite at high differential stresses is consistent with deformation during impact cratering at relatively low shock pressure conditions. The twinned calcite microstructure can serve as a valuable low shock barometer.  相似文献