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  • 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas  (5)
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  • 1
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    Unknown
    Composition and thermal structure of the lithosphere beneath the Ethiopian plateau: evidence from mantle xenoliths in basanites, Injibara, Lake Tana Province (2007)
    Details
    Publication Date: 2017-04-04
    Description: Petrographic, minerochemical, and geothermobarometric data are reported for a suite of 19 spinel-lherzolite pargasite xenoliths hosted in a Quaternary basanitic lava flow from 20 the North-Western Ethiopian Plateau (Injibara, Lake Tana Province). Protogranular to 21 porphyroclastic (deformed) rocks show evidence of a modal metasomatism, represented 22 by a Cl-rich pargasitic amphibole, coupled with criptic enrichment in Fe and Al. 23 Equigranular rocks (granular) record a further cryptic metasomatism, represented by 24 enrichment in Fe, Al, Na, and depletion in Ni, Cr and Cl. Some xenoliths (transitional) 25 show intermediate textural and compositional characters, indicating that the granular 26 samples represent an evolution of the deformed ones. All xenoliths give the same P–T 27 equilibration conditions for Opx-Cpx pairs (947–1015 C and 1.3–2 GPa), but in 28 granular samples, recrystallised olivine and spinel record T about 100 C higher. Two 29 distinct metasomatic processes, probably connected with the emplacement of the Afar plume, are proposed. The first one is a pervasive modal metasomatism produced by 2 water-rich fluids. The latter is a non-pervasive cryptic metasomatism, probably con- 3 nected to migration of melts. The comparison among the mantle beneath the Ethiopi- 4 an Volcanic Plateau, the southern Main Ethiopian Rift and the central Main Ethiopian 5 Rift suggests a spatial heterogeneity in mantle processes, during asthenospheric 6 upwelling.
    Description: In press
    Description: 1–32
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: reserved
    Keywords: lithosphere ; Ethiopian ; 04. Solid Earth::04.01. Earth Interior::04.01.01. Composition and state ; 04. Solid Earth::04.04. Geology::04.04.05. Mineralogy and petrology ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: manuscript
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  • 2
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    Unknown
    Coexisting calc-alkaline and ultrapotassic magmatism at Monti Ernici,Mid Latina Valley (Latium, central Italy) (2007)
    E SCHWEIZERBARTSCHE VERLAGS
    Details
    Publication Date: 2017-04-04
    Description: New major and trace element data, and Sr–Nd–Pb-O isotopic ratios for volcanic mafic rocks outcropping at Monti Ernici in the Mid Latina Valley (southern Latium) are reported, with the aim of investigating the nature and evolution of Plio- Quaternary K-rich volcanism in Central Italy. Petrographical and geochemical studies allow us to identify mafic rocks ranging from ultrapotassic (HKS) to shoshonitic (SHO), and calc-alkaline (CA), these last ones being identified for the first time. The CA rocks exhibit the most primitive signatures for Sr, Nd, and Pb isotopes (87Sr/86Sr = 0.706326-0.706654; 143Nd/144Nd = 0.512388– 0.512361; 206Pb/204Pb = 18.944-18.940). The δ18O values are variable (δ18Ocpx from +5.75 to +7.08 ‰; and δ18Ool from +5.50 to +6.23 ‰), suggesting interaction with carbonate wall rocks. Radiogenic isotope ratios and incompatible elements distribution have several characteristic in common with equivalent rocks from Pontine Islands (Ventotene), Campania and Aeolian arc volcanoes. Conversely, the HKS rocks closely resemble the ultrapotassic rocks from the Roman Province (87Sr/86Sr = 0.709679–0.711102; δ18Ocpx from +6.27 to +7.08 ‰). The high ratios of LILE (Large Ion Lithophile Elements: Rb, Cs, Th, U, K, LREE) and HFSE (High Field Strength Elements: Ta, Nb, Zr, Hf, Ti), and radiogenic isotope compositions of CA to HKS rocks indicate that all suites contain subduction-related components, and suggest a N-MORB-type mantle source variably contaminated by hydrous fluids and/or melts released by undergoing slabs, possibly during two distinct stages of metasomatism. The coexistence of ultra-alkaline and sub-alkaline orogenic magmatism, combined with tectonic, geophysical and geological evidence, support the possibility that the mantle beneath central-southern Italy (Ernici-Roccamonfina Province) was vertically zoned and produced different magma suites during time.
    Description: Published
    Description: 479-497
    Description: 3.5. Geologia e storia dei sistemi vulcanici
    Description: JCR Journal
    Description: reserved
    Keywords: Monti Ernici ; Latium magmatic Province ; calcalkaline rocks ; 04. Solid Earth::04.04. Geology::04.04.05. Mineralogy and petrology ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 3
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    Unknown
    Modeling the magma plumbing system of Vulcano (Aeolian Isalnds, Italy) by integrated fluid inclusion geo-barometry, petrology and geophysics. (2007)
    Geological Society of America
    Details
    Publication Date: 2017-04-03
    Description: An integrated petrological, geophysical, and fluid-inclusion model is presented for the internal structure of the active Vulcano Island, Southern Tyrrhenian Sea. The present structure of the magma storage system in the crust consists of two major deep accumulation zones located at 17–21 km and 8–13 km depth, plus a minor one at 1–5 km depth, beneath Fossa Cone. The deepest magma accumulation zone contains mafic melts and is located at the transition between the upper mantle and a granulitic lower crust. This reservoir has been active since the onset of the exposed volcanism, and has undergone continuous fractional crystallization, crustal assimilation, and mixing with primary melts from the mantle. Slightly differentiated magmas from the deep reservoir feed a shallower accumulation zone in the middle and upper crust, or erupt directly to the surface through lateral vents. Deep melts probably enter the shallowest reservoir shortly before magma outbreak at the surface, and may represent the trigger of eruptions. According to our model, magmatic eruptions at Vulcano are related to deep magma dynamics, whereas most of the changes in the geochemical and geophysical parameters observed at the active cone in the last century could be due to shallow depth modification of rock permeability, possibly as a result of cone gravitative instability and/or tectonic events. Implications for strategies of volcano monitoring and for forecasting eruptions are briefly discussed.
    Description: Published
    Description: 17-20
    Description: reserved
    Keywords: plumbing system ; active volcanoes ; fluid inclusions ; volcano monitoring ; Vulcano Island ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Format: 248680 bytes
    Format: application/pdf
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  • 4
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    A CO2-rich magma source beneath the Phlegraean Volcanic District (Southern Italy): (2012)
    Details
    Publication Date: 2017-04-04
    Description: We present a study of olivine-hosted glass/melt inclusions (MIs) in the most primitive rocks erupted at Procida Island, within the Phlegraean Volcanic District (PVD), Southern Italy. MIs were analyzed by combined Scanning Electron Microscopy coupled with Energy Dispersive X-ray-detectors, Wavelength Dispersive X-rayequipped Electron Microprobe and Fourier Transform Infrared (FT-IR) Spectroscopy; notably, the novel Focal- Plane-Array mode provided high-resolution FT-IR images evidencing the distribution of the C–H–O species across samples. Olivines range in composition from Fo85 to Fo90, do not show chemical zoning and are totally anhydrous. The majority of the MIs are glassy, while only few are completely crystallized. Some MIs, however, show the occurrence of crystal nuclei, i.e., nano- to micro-sized pyroxenes and oxides, and appear as lowcrystallized MIs. The glass of crystal-free and low-crystallized MIs shows K-affinity and a compositional range along the basalt, trachy-basalt, shoshonite, tephrite basanite and phono-tephrite array. H2O and CO2 contents up to 2.69 wt.% and 2653 ppm, respectively, define a major degassing trend with small isobaric deviations. The collected data allow recalculating entrapment pressures from ~350 MPa to b50 MPa and suggest that the magma ascent was dominated by degassing. Crystallization was aminor process, likely also consequent to local CO2-fluxing. Mingling occurred between variable degassed and crystallized magma portions during decompression. The geochemical and isotopic data of Procida glasses and rocks, and the compositional relationship between our MIs and those from slightly more evolved and radiogenic Phlegraean products, indicate that Procida basalts are an adequate parental end-member for the PVD. Our data suggest that a CO2- rich magma source was stored at depths of at least 13–14 km (i.e., 350 MPa) beneath the PVD. Fast ascent of magma batches directly started from this depth shortly before PVD trachy-basaltic to shoshonitic eruptions. Such results have implication on volcanic hazard assessment in the PVD area.
    Description: Published
    Description: 66-80
    Description: 3.5. Geologia e storia dei vulcani ed evoluzione dei magmi
    Description: 3.6. Fisica del vulcanismo
    Description: 5.3. TTC - Banche dati vulcanologiche
    Description: JCR Journal
    Description: reserved
    Keywords: Melt inclusions ; Phlegraean Volcanic District ; CO2-rich magma source ; Degassing ; Fluxing ; 02. Cryosphere::02.01. Permafrost::02.01.08. Instruments and techniques ; 04. Solid Earth::04.01. Earth Interior::04.01.02. Geological and geophysical evidences of deep processes ; 04. Solid Earth::04.01. Earth Interior::04.01.04. Mineral physics and properties of rocks ; 04. Solid Earth::04.04. Geology::04.04.05. Mineralogy and petrology ; 04. Solid Earth::04.04. Geology::04.04.07. Rock geochemistry ; 04. Solid Earth::04.04. Geology::04.04.11. Instruments and techniques ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas ; 04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks ; 05. General::05.02. Data dissemination::05.02.01. Geochemical data ; 05. General::05.02. Data dissemination::05.02.03. Volcanic eruptions
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 5
    facet.materialart.
    Unknown
    Constraining the recent plumbing system of Vulcano (Aeolian Arc, Italy) by textural, petrological and fractal analysis: The 1739 AD Pietre Cotte Lava Flow (2009)
    Americal Geophysical Union
    Details
    Publication Date: 2019-12-05
    Description: The 1739 A.D. Pietre Cotte lava flow is part of a sequence of low-explosive to weak effusion events occurred at La Fossa Cone, the active vent on Vulcano Island (Aeolian Arc, Italy). This lava is rhyolitic, texturally heterogeneous, and contains lati-trachytic enclaves. These compositions are recurrent in the La Fossa volcanic products and are representative of the recent Vulcano plumbing system. The host lava is vesicular, relatively phenocryst-free, and locally contains microlites and millimeter-sized spherulites. The enclaves are up to 10 cm in size, display angular to spherical shapes, and can form the core of spherulites. Enclaves mostly consist of plagioclase and augitic phenocrysts set in a weakly vesicular groundmass characterized by variable abundance of glass and feldspar microlites. Field, textural, and fractal data allow us to constrain the rheological features of the rhyolitic and lati-trachytic magmas. In situ major, trace, and volatile element analyses provide evidence for heterogeneities in the glassy matrix and zoning of phenocrysts. Processes of magma evolution have been quantitatively constrained by using the apparent distribution ratios of trace elements measured between mineral phases and glassy matrices. The collected data in combination with petrological and fluid inclusion data from the literature provides evidence for (1) a genetic relationship between the two magmas through assimilation fractional crystallization process; (2) a mingling mechanism between an uprising rhyolitic magma and a shallower partly crystallized lati-trachytic magma plug; (3) the desegregation (enclaves) at variable scales of the lati-trachyte within the rhyolite; and (4) the possible eruptive scenarios consequent to a future magmatic unrest.
    Description: MIUR project ‘‘Fluid dynamic regime of magma mixing/mingling processes’’ and INGV-DPC project 2005–2007 founded by ‘‘Istituto Nazionale di Geofisica e Vulcanolgia,’’ Italy.
    Description: Published
    Description: Q01009
    Description: 3.6. Fisica del vulcanismo
    Description: JCR Journal
    Description: reserved
    Keywords: magma mixing ; lava flow ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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