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  • 1
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    Recovering the composition of melt and the fluid regime at the onset of crustal anatexis and S-type granite formation (2013)
    Geological Society of America (GSA)
    In: Geology
    Details
    Publication Date: 2013-01-30
    Description: Using a metatexite from the Spanish Betic Cordillera as an example, we show that in situ and otherwise impossible to retrieve compositional information on natural anatectic melts can be reliably gained from experimentally rehomogenized melt inclusions in peritectic garnets. Experiments were conducted on single garnet crystals in a piston cylinder apparatus until the complete homogenization of crystal-bearing melt inclusions at the conditions inferred for the anatexis. The compositions of quenched glasses, representative of the early anatectic melts, are leucogranitic and peraluminous, and differ from those of leucosomes in the host rock. The H 2 O contents in the glasses suggest that melts formed at low temperature (~700 °C) may not be as hydrous and mobile as thought. Providing for the first time the precise melt composition (including the volatile components) in the specific anatectic rock under study, our approach improves our understanding of crustal melting and generation of S-type granites.
    Print ISSN: 0091-7613
    Electronic ISSN: 1943-2682
    Topics: Geosciences
    Published by Geological Society of America (GSA)
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  • 2
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    The chemical behavior of fluids released during deep subduction based on fluid inclusions (2015)
    Mineralogical Society of America
    Details
    Publication Date: 2015-02-13
    Description: This review combines fluid inclusion data from (HP-)UHP rocks with experimental research and thermodynamic models to investigate the chemical and physical properties of fluids released during deep subduction, their solvent and element transport capacity, and the subsequent implications for the element recycling in the mantle wedge. An impressive number of fluid inclusion studies indicate three main populations of fluid inclusions in HP and UHP metamorphic rocks: (1) aqueous and/or non-polar gaseous fluid inclusions (FI); (2) multiphase solid inclusions (MSI); and (3) melt inclusions (MI). Chemical data from preserved fluid inclusions in rocks match with and implement "model" fluids by experiments and thermodynamics, revealing a continuity behind the extreme variations of physico-chemical properties of subduction-zone fluids. From fore-arc to sub-arc depths, fluids released by progressive devolatilization reactions from slab lithologies change from relatively diluted chloride-bearing aqueous solutions (±N 2 ), mainly influenced by halide ligands, to (alkali) aluminosilicate-rich aqueous fluids, in which polymerization probably governs the solubility and transport of major (e.g., Si and Al) and trace elements (including C). Fluid inclusion studies point to a reconsideration of the petrological models explaining deep volatile liberation, and their flux into the mantle wedge.
    Print ISSN: 0003-004X
    Electronic ISSN: 1945-3027
    Topics: Geosciences
    Published by Mineralogical Society of America
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  • 3
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    Dissolving dolomite in a stable UHP mineral assemblage: Evidence from Cal-Dol marbles of the Dora-Maira Massif (Italian Western Alps) (2017)
    Mineralogical Society of America
    Details
    Publication Date: 2017-01-04
    Description: In deep and cold subduction such as that experienced by the UHP Units of the Western Alps, carbon dissolution is a relevant mechanism for carbon transfer from the slab into the mantle. The UHP impure Cal-Dol-marbles from the Dora-Maira Massif are studied to investigate the poorly known evolution of dolomite during deep subduction. Dolomite shows four stages of growth, from pre-Alpine to early-retrograde Alpine, coupled with chemical variations and distinct included mineral assemblages. To explain the evidence for growth and partial reabsorption of dolomite through HP prograde, UHP peak, and UHP early-retrograde Alpine metamorphism, a chemically simple marble (Cal, Dol, Di, Fo, and retrograde Atg, Tr, Mg-Chl) has been studied in detail. Microstructural relationships, coupled with mineral chemistry, indicate the growth of the assemblage dolomite+diopside+forsterite±aragonite during HP prograde, UHP peak, and UHP early-retrograde evolution. Mixed-volatile P-T projection modeled in the simple CaO-(FeO)-MgO-SiO 2 -H 2 O-CO 2 system and $$T-P-{X}_{{\mathrm{CO}}_{2}}$$ petrogenetic grids and pseudosections predict the prograde (1.7 GPa, 560 °C) growth of dolomite in equilibrium with diopside and forsterite through the breakdown of antigorite+aragonite. In a H 2 O-CO 2 -saturated system, the subsequent HP-UHP evolution is predicted in the Di+Fo+Dol+Arg stability field in equilibrium with a dominantly aqueous COH fluid [ $$0.0003 〈 {X}_{{\mathrm{CO}}_{2}} 〈 0.0008$$ ], whose composition is internally buffered by the equilibrium assemblage. Thermodynamic modeling indicates that neither the consumption nor the growth of new dolomite generations at UHP conditions can have been induced by metamorphic reactions. The abundant primary H 2 O+Cal+Dol+Cl-rich Tr+Cl-rich Tlc±chloride fluid inclusions present in UHP Cpx indicate that a dominantly aqueous, saline (salinity 〉26.3 wt% of NaCl eq ) COH fluid, containing Ca, Mg, and Si as dissolved cations was present during the growth of the UHP assemblage Dol+Cpx+Ol+Arg. The complex zoning of dolomite is therefore interpreted as due to protracted episodes of dissolution and precipitation in saline aqueous fluids at HP/UHP conditions. Kinetics of dolomite dissolution in aqueous fluids is poorly known, and experimental and thermodynamic data under HP conditions are still lacking. Data on calcite indicate that dissolution at HP is enhanced by a prograde increase in both P and T , by high salinity in aqueous fluids, and/or low-pH conditions. In the studied marble, the P-T path and the occurrence of free high-saline fluids represent favorable conditions: (1) for the inferred dissolution-precipitation processes of the stable dolomite in a closed system, and (2) for possible migration of the dissolved carbonate, if the system would have been open during subduction.
    Print ISSN: 0003-004X
    Electronic ISSN: 1945-3027
    Topics: Geosciences
    Published by Mineralogical Society of America
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  • 4
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    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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  • 5
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    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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  • 6
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    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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  • 7
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    Evolution of the volcanic plumbing systemof Alicudi (Aeolian Islands - Italy): evidence from fluid and melt inclusionsin quartz xenoliths (2006)
    INGV
    Details
    Publication Date: 2019-11-04
    Description: Quartz-rich xenoliths in lavas (basalts to andesites; 90-30 ka) from Alicudi contain abundant melt and fluid inclusions. Two generations of CO2-rich fluid inclusions are present in quartz-rich xenolith grains: early (Type I) inclusions related to partial melting of the host xenoliths, and late Type II inclusions related to the fluid trapping during xenolith ascent. Homogenisation temperatures of fluid inclusions correspond to two density intervals: 0.93-0.68 g/cm3 (Type I) and 0.47-0.26 g/cm3 (Type II). Early Type I fluid inclusions indicate trapping pressures around 6 kbar, which are representative for the levels of partial melting of crustal rocks and xenolith formation. Late Type II fluid inclusions show lower trapping pressures, between 1.7 kbar and 0.2 kbar, indicative for shallow magma rest and accumulation during ascent to the surface. Data suggest the presence of two magma reservoirs: the first is located at lower crustal depths (about 24 km), site of fractional crystallization, mixing with source derived magma, and various degrees of crustal assimilation. The second magma reservoir is located at shallow crustal depths (about 6 km), the site where magma rested for a short time before erupting.
    Description: Published
    Description: JCR Journal
    Description: open
    Keywords: Aeolian Islands ; fluid inclusions ; crustal xenoliths ; homogenisation temperature ; magma plumbing system ; 04. Solid Earth::04.08. Volcanology::04.08.03. Magmas
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Format: 1924338 bytes
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  • 8
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    Composition and thermal structure of the lithosphere beneath the Ethiopian plateau: evidence from mantle xenoliths in basanites, Injibara, Lake Tana Province (2012)
    Springer-Verlag
    Details
    Publication Date: 2020-02-24
    Description: Petrographic, minerochemical, and geothermobarometric data are reported for a suite of spinel-lherzolite pargasite xenoliths hosted in a Quaternary basanitic lava flow from the North-Western Ethiopian Plateau (Injibara, Lake Tana Province). Protogranular to porphyroclastic (deformed) rocks show evidence of a modal metasomatism, represented by a Cl-rich pargasitic amphibole, coupled with cryptic enrichment in Fe and Al. Equigranular rocks (granular) record a further cryptic metasomatism, represented by enrichment in Fe, Al, Na, and depletion in Ni, Cr and Cl. Some xenoliths (transitional) show intermediate textural and compositional characters, indicating that the granular samples represent an evolution of the deformed ones. All xenoliths give the same P–T equilibration conditions for Opx-Cpx pairs (947–1015 C and 1.3–2.0 GPa), but in granular samples, recrystallised olivine and spinel record T about 100 C higher. Two distinct metasomatic processes, probably connected with the emplacement of the Afar plume, are proposed. The first one is a pervasive modal metasomatism produced by water-rich fluids. The latter is a non-pervasive cryptic metasomatism, probably connected to migration of melts. The comparison the mantle beneath the Ethiopian Volcanic Plateau, the southern Main Ethiopian Rift and the central Main Ethiopian Rift suggests spatial heterogeneity of the mantle and variable mantle processes during asthenospheric upwelling.
    Description: Published
    Description: 47-78
    Description: 3.3. Geodinamica e struttura dell'interno della Terra
    Description: JCR Journal
    Description: reserved
    Keywords: lithosphere ; peridotite xenoliths ; Ethiopian Volcanic Plateau ; Metasomatism ; 04. Solid Earth::04.04. Geology::04.04.05. Mineralogy and petrology
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 9
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    Geology, volcanic history and petrology of Vulcano (central Aeolian archipelago) (2015)
    Geological Society Publishing House
    Details
    Publication Date: 2021-12-06
    Description: Vulcano is an active NW–SE-elongated composite volcano located in the central Aeolian archipelago. Based on available radiometric ages and tephrochronology, the exposed volcanism started at c. 127 ka and spread through eight Eruptive Epochs separated by volcano-tectonic events and major quiescent stages. Various eruptive centres and two intersecting multi-stage calderas resulted from such evolution. Vulcano geological history displays several changes of eruption magnitude, eruption styles and composition of magmas through time. Vulcano rocks range from basalt to rhyolite and show variable alkali contents, roughly increasing during time. Magmas with low to intermediate SiO2 contents and high-K to shoshonite affinity prevail in the early Epochs 1–5 (c. 127–28 ka), whereas intermediate to high-SiO2 shoshonite and potassic alkaline products dominate the last three Epochs (〈30 ka). This sharp increase in silicic products is related to the shallowing of the plumbing system and resulting major role of the differentiation processes in shallow level reservoirs. Radiogenic isotope compositions are variable (87Sr/86Sr = 0.70424–0.70587, 143Nd/144Nd = 0.51254–0.51276, 206Pb/204Pb = 19.305–19.759, 207Pb/204Pb = 15.659–15.752, 208Pb/204Pb = 39.208–39.559) as a result of both source heterogeneities and shallow-level interaction of magmas with continental crust. The compositional variations of mafic magmatism with time suggest that the source zone changed from a metasomatized, fertile, ocean island basalt- (OIB-) like mantle to a metasomatized depleted lithospheric mantle.
    Description: Published
    Description: 281-349
    Description: 1V. Storia e struttura dei sistemi vulcanici
    Description: JCR Journal
    Description: restricted
    Keywords: volcanic history, stratigraphy, mapping, geochemistry, volcanic hazard ; 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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