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Browsing by Author "De Vivo, Benedetto"

Now showing 1 - 7 of 7
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    Composition and origin of nodules from the ≈20 ka Pomici di Base (PB)-Sarno eruption of Mt. Somma – Vesuvius, Italy
    Klébesz, Rita; Bodnar, Robert J.; De Vivo, Benedetto; Török, Kálmán; Lima, Annamaria; Petrosino, Paola (De Gruyter, 2012-05-13)
    Nodules (coarse-grain “plutonic” rocks) were collected from the ca. 20 ka Pomici di Base (PB)-Sarno eruption of Mt. Somma-Vesuvius, Italy. The nodules are classified as monzonite-monzogabbro based on their modal composition. The nodules have porphyrogranular texture, and consist of An-rich plagioclase, K-feldspar, clinopyroxene (ferroan-diopside), mica (phlogopite-biotite) ± olivine and amphibole. Aggregates of irregular intergrowths of mostly alkali feldspar and plagioclase, along with mica, Fe-Ti-oxides and clinopyroxene, in the nodules are interpreted as crystallized melt pockets. Crystallized silicate melt inclusions (MI) are common in the nodules, especially in clinopyroxenes. Two types of MI have been identified. Type I consists of mica, Fe-Ti-oxides and/or dark green spinel, clinopyroxene, feldspar and a vapor bubble. Volatiles (CO2, H2O) could not be detected in the vapor bubbles by Raman spectroscopy. Type II inclusions are generally lighter in color and contain subhedral feldspar and/or glass and several opaque phases, most of which are confirmed to be oxide minerals by SEM analysis. Some of the opaque-appearing phases that are below the surface may be tiny vapor bubbles. The two types of MI have different chemical compositions. Type I MI are classified as phono-tephrite — tephri-phonolite — basaltic trachy-andesite, while Type II MI have basaltic composition. The petrography and MI geochemistry led us to conclude that the nodules represent samples of the crystal mush zone in the active plumbing system of Mt. Somma-Vesuvius that were entrained into the upwelling magma during the PB-Sarno eruption.
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    Compositional variation and zoning of epidote supergroup minerals in the Campi Flegrei geothermal field, Naples, Italy
    Belkin, Harvey E.; De Vivo, Benedetto (Copernicus, 2023-01-06)
    Authigenic epidote supergroups are an abundant accessory mineral in the calcium-aluminum silicate and thermometamorphic hydrothermal zones of the Campi Flegrei (Phlegraean Fields) geothermal field located west of Naples, Italy. Geothermal exploration for high-enthalpy fluid produced drill core and cuttings to similar to 3 km depth in the Mofete (MF1, MF2, MF5) and San Vito (SV1, SV3) wells, where measured down-hole temperatures of epidote-bearing samples range from 270-350 degrees C and from 285-390 degrees C for the Mofete and San Vito areas, respectively. Two epidote group (epidote, clinozoisite), some rare earth element (REE)-bearing, and two allanite group (allanite-(Ce), ferriallanite-(Ce)) minerals were identified by electron microprobe. The allanite group is light rare earth element (LREE, La-Gd) enriched, Ce dominant, with REE + Y that varies from 30.59 wt %-14.32 wt %. Complex compositional variation such as oscillatory, sector, and complex (mixed) zoning is a ubiquitous feature observed in the epidote group, which occurs as veins, in vugs, as various size masses, and as isolated single crystals. Compositional zoning is caused by variable Fe <-> Al3+ substitution and XFe [(Fe3+) / (Fe3++Al)] ranges from 0.06-0.33 (Fe3+ = 0.185-0.967 apfu). X-Fe tends to decrease with increasing temperature in the Mofete wells, but its distribution is more complex in the San Vito wells, which records recent fault displacement. The variety and complexity of the epidote supergroup zoning suggest rapid fluid composition and/or intensive parameter fluctuations in the local hydrothermal system.
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    Factors influencing the bioavailability of some selected elements in the agricultural soil of a geologically varied territory: The Campania region (Italy) case study
    Guarino, Annalise; Albanese, Stefano; Cicchella, Domenico; Ebrahimi, Pooria; Dominech, Salvatore; Pacifico, Lucia Rita; Rofrano, Giuseppe; Nicodemo, Federico; Pizzolante, Antonio; Allocca, Carolina; Romano, Nunzio; De Vivo, Benedetto; Lima, Annamaria (Elsevier, 2022-12-15)
    Bioavailability of some major and trace elements was evaluated in 1,993 topsoil samples collected across Campania region (Southern Italy). A main focus was made on Al, Ca, K, Mg, Cu, Tl since they are linked, for different reasons, to agriculture. Bioavailability was assessed by an extraction with ammonium nitrate and the data were compared with the pseudo-total concentration determined by Aqua Regia digestion. Geochemical maps of the pseudo-total and bioavailable concentrations were generated using a multifractal inverse distance weighted (MIDW) interpolation. In addition, the spatial distribution patterns of the percent bioavailability of elements, based on the ratio among bioavailable and the pseudo-total fractions, were also determined. The median value of the percent bioavailability showed the order Ca > K >> Mg. Tl >> Cu >> Al and it represents a positive finding in terms of both agricultural productivity and environmental quality. Further, a multiple linear regression was finally applied to data to unveil any dependence of the bioavailable fraction on the pseudo-total content of elements. The grain size distribution and organic matter content of samples were later included to evaluate their possible role in promoting the environmental availability of elements. The pseudo-total concentrations of Al, Ca, K, and Mg alone resulted to be poorly able to predict the variability of the bioavailable fraction. The addition of the grain size distribution and organic matter content to the models expanded the predictive capability of Ca, K, and Mg whereas a marginal improvement was showed by Al, Cu, and Tl. This study represents a methodological contribution to a better understanding of the processes underlying the spatial variability of chemical elements in soil. Considering the positive outcomes obtained, further researches were planned to include more variables (e.g. soil pH, redox potential, content in Iron and Manganese oxides, etc.) in the predictive models.
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    Geochemistry of Melt Inclusions from the Fondo Riccio and Minopoli 1 Eruptions at Campi Flegrei (Italy)
    Cannatelli, Claudia (Virginia Tech, 2006-05-18)
    Campi Flegrei is a large volcanic complex located west of the city of Naples, Italy. The area has been the site of volcanic activity for more than 60 ka and represents a potential volcanic hazard owing to the large local population. In this study, the geochemistry of the magma associated with two different eruptions at Campi Flegrei has been characterized, with the aim to identify geochemical trends that may help to predict the style and nature of future eruptions. Two eruptions of different age and eruptive style have been selected for study, Fondo Riccio (9.5 ka) and Minopoli 1 (11.1 ka). A scoria (CF-FR-C1) and a bomb (CF-FR-C2) were collected from the Fondo Riccio eruption, and two scoria samples were collected from Minopoli 1 (CF-Mi1-C1 and C2) eruption. The pre-eruptive volatile content of magma plays an important role in the style of eruption and can be assessed from studies of melt inclusions (MI) contained in phenocrysts. Major and trace elements in Fondo Riccio MI show a wider variation compared to those in Minopoli 1 MI suggesting that the Fondo Riccio magma residence time was longer compared to the Minopoli 1 magma. Analyses of volatile contents in MI suggest that Fondo Riccio magma may have been more water-rich than Minopoli 1 magma, consistent with the more explosive character of this eruption compared to Minopoli 1. Trace element data suggest a combination of arc volcanic and upper continental crust magma as the source for the Fondo Riccio and Minopoli 1 eruptions.
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    A new approach to assess the degree of contamination and determine sources and risks related to PTEs in an urban environment: the case study of Santiago (Chile)
    Aruta, Antonio; Albanese, Stefano; Daniele, Linda; Cannatelli, Claudia; Buscher, Jamie T.; De Vivo, Benedetto; Petrik, Attila; Cicchella, Domenico; Lima, Annamaria (Springer, 2022-01-10)
    In 2017, a geochemical survey was carried out across the Commune of Santiago, a local administrative unit located at the center of the namesake capital city of Chile, and the concentration of a number of major and trace elements (53 in total) was determined on 121 topsoil samples. Multifractal IDW (MIDW) interpolation method was applied to raw data to generate geochemical baseline maps of 15 potential toxic elements (PTEs); the concentration-area (C-A) plot was applied to MIDW grids to highlight the fractal distribution of geochemical data. Data of PTEs were elaborated to statistically determine local geochemical baselines and to assess the spatial variation of the degree of soil contamination by means of a new method taking into account both the severity of contamination and its complexity. Afterwards, to discriminate the sources of PTEs in soils, a robust Principal Component Analysis (PCA) was applied to data expressed in isometric log-ratio (ilr) coordinates. Based on PCA results, a Sequential Binary Partition (SBP) was also defined and balances were determined to generate contrasts among those elements considered as proxies of specific contamination sources (Urban traffic, productive settlements, etc.). A risk assessment was finally completed to potentially relate contamination sources to their potential effect on public health in the long term. A probabilistic approach, based on Monte Carlo method, was deemed more appropriate to include uncertainty due to spatial variation of geochemical data across the study area. Results showed how the integrated use of multivariate statistics and compositional data analysis gave the authors the chance to both discriminate between main contamination processes characterizing the soil of Santiago and to observe the existence of secondary phenomena that are normally difficult to constrain. Furthermore, it was demonstrated how a probabilistic approach in risk assessment could offer a more reliable view of the complexity of the process considering uncertainty as an integral part of the results.
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    Studies of Magmatic Systems
    Fedele, Luca (Virginia Tech, 2002-05-09)
    Two magmatic systems were investigated using different petrological tools: 1) Origin of Ponza trachyte was studied combining data from MI with trends predicted by thermodynamic modeling. MI data were compared with known phase relations in the ternary feldspar and anorthite-diopside-albite systems to constrain the parameters used in the modeling. MI data are consistent with melt evolution from a basaltic parent via a fractional crystallization mainly of pyroxene and feldspars. These data and the results from the modeling, suggest a genetic link between the Ponza trachyte and coeval alkali olivine basalts on the nearby Ventotene Island. 2) We evaluated the range of magmatic temperatures within the crystallization interval for a basanite with different olivine-spinel geothermometers. While olivine spinel pair records the evolution of the basanite during crystallization, low temperatures calculated with the geothermometers are unrealistic. This is likely due to the presence of significant amounts of Ti in our magmatic spinels. Indeed Ti is not taken into account in the geothermometers. We tested the possibility of accounting for the presence and effects of Ti using a linear correction for the Fe+2 content in our spinels. While this generated more realistic temperatures at the low end of the range, it also increased the dispersion in the data, suggesting that spinel behavior is more complex and that the presence of Ti affects content and site occupancy of other elements as well.
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    Studies of volatile evolution in magmatic systems using melt inclusions
    Esposito, Rosario (Virginia Tech, 2012-07-02)
    Understanding volatile evolution associated with active volcanic magmatic systems is of paramount importance because volatiles control and determine the magnitude of an eruption owing to the large change in molar volume that volatile species show depending on their physical state (volatiles dissolved in silicate melts vs. volatiles exsolved as vapor). For active volcanic systems studying the volatile evolution can help to assess the potential hazard associated to a certain locality. Also, volatile evolution in magmatic system controls the formation of certain ore deposits. Despite the importance of understanding volatile evolution of magmatic systems, concentrations of volatiles of evolving magmas are not easily available especially for magmas originated in the deep crust. Fortunately, sample of melts can be entrapped as melt inclusion (MI) into growing igneous minerals in crystalizing magma chamber. After the entrapment, the crystal works as an insulating capsule from the external magmatic environment. Researchers have started to use MI because they provide some advantages in respect to the classical whole rock approach to petrological studies. One of the most important advantages is that MI often represent sample of a deep and non-degassed melt (glass) available at Earth's surface. In fact, with the exception of deep ocean basalts, igneous whole rocks found at the Earth's surface are degassed magmas. This dissertation is a compilation of four publications produced during six years of research and is addressed to give a contribution in understanding the volatile evolution in magmatic systems and also to improve the present understanding of information that can be obtained using the melt inclusions technique. In the first chapter, I present an alternative interpretation of H₂O-CO₂ trends obtained from MI. In this study, we demonstrate that these trends can be due to post entrapment crystallization on the wall of the MI and not to magma ascent. This alternative view is more realistic especially for cases where in the same phenocrysts MI show strongly different CO₂ concentrations. In the second chapter, I present a study to test for the MI reliability in recording volatile concentrations. We used the approach of the melt inclusion assemblage (MIA) that consists of analyzing groups of MI presumably entrapped at the same time and, thus, at same chemical and physical conditions. The results show that most of the MIA studied show consistent volatile concentrations corroborating the reliability of the MI technique. CO₂ shows the highest degrees of variability and we have assessed this behavior mostly to C-contamination in the surface of the sample. The third chapter is a study case (the Solchiaro eruption in Southern Italy) that shows the potential uses of MI to understanding the volatile evolution. I present a model showing the dynamic of the magma based on MI. This study also discusses the origin of anomalous MI and which MI provide the best information. The final chapter is dedicated to test the applicability of the new Linkam TS1400XY heating stage. I was able to show how this new microthermometric tool is capable of homogenizing MI at high temperature and to quench MI to a homogeneous glass state.