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  • 1
    Digitale Medien
    Digitale Medien
    Transition from calc-alkaline to potassium-rich magmatism in subduction environments: geochemical and Sr, Nd, Pb isotopic constraints from the island of Vulcano (Aeolian arc) (2000)
    Springer
    Contributions to mineralogy and petrology 139 (2000), S. 684-703 
    Details
    ISSN: 1432-0967
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Geologie und Paläontologie
    Notizen: Abstract The problem of mantle metasomatism vs. crustal contamination in the genesis of arc magmas with different potassium contents has been investigated using new trace element and Sr–Nd–Pb isotopic data on the island of Vulcano, Aeolian arc. The analysed rocks range in age from 120 ka to the present day, and cover a compositional range from basalt to rhyolite of the high-K calc-alkaline (HKCA) to shoshonitic (SHO) and potassic (KS) series. Older Vulcano products (〉30 ka) consist of HKCA–SHO rocks with SiO2=48–56%. They show lower contents of K2O, Rb and of several other incompatible trace element abundances and ratios than younger rocks with comparable degree of evolution. 87Sr/86Sr ranges from 0.70417 to 0.70504 and increases with decreasing MgO and compatible element contents. 206Pb/204Pb ratios display significant variations (19.31 to 19.76) and are positively correlated with MgO, 143Nd/144Nd (0.512532–0.512768), 207Pb/204Pb (15.66–15.71) and 208Pb/204Pb (39.21–39.49). Overall, geochemical and isotopic data suggest that the evolution of the older series was dominated by assimilation–fractional crystallisation (AFC) with an important role for continuous mixing with mafic liquids. Magmas erupted within the last 30 ka consist mostly of SHO and KS intermediate and acid rocks, with minor mafic products. Except for a few acid rocks, they display moderate isotopic variations (e.g. 87Sr/86Sr=0.70457–0.70484; 206Pb/204Pb=19.28–19.55, but 207Pb/204Pb=15.66–15.82), which suggest an evolution by fractional crystallisation, or in some cases by mixing, with little interaction with crustal material. The higher Sr isotopic ratios (87Sr/86Sr=0.70494–0.70587) of a few, low-volume, intermediate to acid rocks support differentiation by AFC at shallow depths for some magma batches. New radiogenic isotope data on the Aeolian islands of Alicudi and Stromboli, as well as new data for lamproites from central Italy, are also reported in order to discuss along-arc compositional variations and to evaluate the role of mantle metasomatism. Geochemical and petrological data demonstrate that the younger K-rich mafic magmas from Vulcano cannot be related to the older HKCA and SHO ones by intra-crustal evolutionary processes and point to a derivation from different mantle sources. The data from Alicudi and Stromboli suggest that, even though interaction between magma and wall rocks of the Calabrian basement during shallow level magma evolution was an important process locally, a similar interpretation can be extended to the entire Aeolian arc.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s004100000172
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  • 2
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    Multiple hazards and paths to eruptions: A review of the volcanic system of Vulcano (Aeolian Islands, Italy) (2020)
    Elsevier
    Details
    Publikationsdatum: 2020-10-07
    Beschreibung: Vulcano is one of the 7 volcanic islands and 6 seamounts forming the Aeolian volcanic district (Italy). Vulcano has a long eruptive record, and its last eruption (1888–90 AD) originated the definition of the Vulcanian eruptive style. Like most volcanic islands, Vulcano generates many potentially interconnected hazards, determining a potentially high risk. Here, we review the state of knowledge on its geology, eruptive activity, historical accounts, structural setting, geophysical and geochemical surveillance, and available hazard assessment, in order to have an updated picture of the state knowledge on volcanic hazard. We follow a prototypal reviewing scheme, based on three standardized steps: i) review of the volcanic system; ii) review of available eruptive and noneruptive hazard quantifications; iii) development of a conceptual interpretative model. We find that, while a rather vast literature is dedicated to the volcanic system of Vulcano and the reconstruction of past events, few quantitative hazard assessments exist. In addition, the range of natural variability considered for each hazard is potentially underestimated (e.g. limited range of considered eruption magnitude and style and of vent position), as it is the potential effect of multi-hazard impact. The developed conceptual model for the feeding system provides a synthetic picture of the present knowledge about the system, as emerged from the review. In addition, it allows for the identification of potential paths-to-eruption and provides a first order link among the main hazards. This review provides an up-to-date snapshot of existing knowledge on volcanic hazard at Vulcano on which to build future hazard quantifications as well as to support present and future decision making.
    Beschreibung: Published
    Beschreibung: 103186
    Beschreibung: 1V. Storia eruttiva
    Beschreibung: JCR Journal
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 3
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    Geological Map of the Tocomar Basin (Puna Plateau, NW Argentina). Implication for the Geothermal System Investigation (2020)
    MDPI
    Details
    Publikationsdatum: 2020-10-26
    Beschreibung: This paper presents a detailed geological map at the 1:20,000 scale of the Tocomar basin in the Central Puna (north-western Argentina), which extends over an area of about 80 km2 and displays the spatial distribution of the Quaternary deposits and the structures that cover the Ordovician basement and the Tertiary sedimentary and volcanic units. The new dataset includes litho-facies descriptions, stratigraphic and structural data and new 234U/230Th ages for travertine rocks. The new reconstructed stratigraphic framework, along with the structural analysis, has revealed the complex evolution of a small extensional basin including a period of prolonged volcanic activity with different eruptive centres and styles. The geological map improves the knowledge of the geology of the Tocomar basin and the local interplay between orogen-parallel thrusts and orogen-oblique fault systems. This contribution represents a fundamental support for in depth research and also for encouraging geothermal exploration and exploitation in the Puna Plateau region.
    Beschreibung: Published
    Beschreibung: id 5492
    Beschreibung: 1TR. Georisorse
    Beschreibung: JCR Journal
    Schlagwort(e): geothermal exploration ; U/Th dating ; Southern Central Andes ; central Puna ; 04. Solid Earth ; 04.04. Geology
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 4
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    Petrological and geochemical modeling of magmas erupted at Vulcano Island in the period 54–8 ka: Quantitative constraints on the sub-volcanic architecture of the plumbing system (2021)
    Elsevier
    Details
    Publikationsdatum: 2021-01-14
    Beschreibung: In this study, we present new mineralogical and petrological data from fifteen eruptive products erupted at Vulcano Island (Aeolian Arc, Italy) over a period of time from 54 to 8 ka and representative of the Eruptive Epochs from 5 to 8 of this volcanic system. These rocks show shoshonitic (SHO) to high-K calc-alkaline (HKCA) affinity, with compositions changing from primitive basalts-shoshonites (Mg#35–60) to intermediate latites (Mg#32–54) to evolved trachytes-rhyolites (Mg#23–40). The intensive variables driving the crystallization path of magmas were reconstructed through mineral-melt equilibrium and thermodynamic models, as well as barometers, thermometers, hygrometers and oxygen barometers. The stability of olivine (Fo59–91), as first phase on the liquidus, is more favored at low-P (100–300 MPa) and high-H2O (4 wt%) contents dissolved in the melt. Afterwards, the melt is co-saturated with clinopyroxene (Mg#92, diopside), whose composition progressively evolves (Mg#71, augite) as the temperature decreases to 1100 °C. The crystallization pressure recorded by clinopyroxene decreases from basalts (550–750 MPa) to shoshonites-latites-trachytes (100–450 MPa) to rhyolites (~50 MPa). The melt-H2O content (0.5–4.2 wt%) is sensitive to either pressure or melt composition, thereby controlling the plagioclase stability and chemistry (An13–77) within a thermal path of ~860–1100 °C. Titanomagnetite (Usp11–39) equilibrates with progressively more oxidized melts as the magma composition changes from basalt (ΔQFM+1.5) to rhyolite (ΔQFM+3). Mass balance calculations and trace element modeling indicate that basaltic to trachytic magmas are prevalently controlled by fractional crystallization processes, in concert with variable degrees of assimilation of crustal rocks. Conversely, rhyolitic and highly differentiated trachytic magmas are generated by extraction of interstitial melts from shallow mush zones dominated by feldspar and titanomagnetite saturation. We conclude that the architecture of the plumbing system at Vulcano Island is characterized by multiple reservoirs in which compositionally distinct magmas pond and undergo polybaric-polythermal differentiation, before erupting to the surface.
    Beschreibung: Published
    Beschreibung: 105715
    Beschreibung: 3V. Proprietà chimico-fisiche dei magmi e dei prodotti vulcanici
    Beschreibung: JCR Journal
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 5
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    Trace element partitioning between clinopyroxene and trachy-phonolitic melts: A case study from the Campanian Ignimbrite (Campi Flegrei, Italy) (2020)
    Details
    Publikationsdatum: 2021-05-17
    Beschreibung: The partitioning of trace elements between crystals and melts provides an important petrogenetic tool for understanding magmatic processes. We present trace element partition coefficients measured between clinopyroxene phenocrysts and trachy-phonolitic magmas at the Campi Flegrei (Italy), whose late Quaternary volcanism has been characterized by two major caldera-forming events (Campanian Ignimbrite at similar to 39 ka, and Neapolitan Yellow Tuff at similar to 15 ka). Our data indicate that the increase of trivalent rare earth elements and yttrium into the crystal lattice M2 site is facilitated by the charge-balancing substitution of Si4+ with Al3+ on the tetrahedral site. Higher concentrations of tetravalent and pentavalent high field strength elements on the M1 site are also measured when the average charge on this site is increased by the substitution of divalent cations by Al-vi. In contrast, due to these charge balance requirements, divalent transitional elements become less compatible within the crystal lattice. On the basis of the lattice strain theory, we document that the incorporation of rare earth elements and yttrium in clinopyroxene is influenced by both compositional and physical parameters. Data from this study allow to update existing partitioning equations for rare earth elements in order to construct a self-consistent model for trachy-phonolitic magmas based on the lattice strain theory. The application of this model to natural products from the Campanian Ignimbrite, the largest caldera-forming eruption at the Campi Flegrei, reveals that the complex rare earth element pattern recorded by the eruptive products can be successfully described by the stepwise fractional crystallization of clinopyroxene and feldspar where the clinopyroxene-melt partition coefficient changes progressively as a function of the physicochemical conditions of the system. (c) 2016 Elsevier B.V. All rights reserved.
    Beschreibung: Published
    Beschreibung: 160-172
    Beschreibung: 3V. Proprietà chimico-fisiche dei magmi e dei prodotti vulcanici
    Beschreibung: JCR Journal
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 6
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    Landslide susceptibility mapping on the islands of Vulcano and Lipari (Aeolian Archipelago, Italy), using a multi-classification approach on conditioning factors and a modified GIS matrix method for areas lacking in a landslide inventory (2020)
    Details
    Publikationsdatum: 2021-05-12
    Beschreibung: In areas prone to landslides, the identification of potentially unstable zones has a decisive impact on the risk assessment and development of mitigation plans. Active volcanic islands are particularly prone to instability phenomena as they are always in the early stage of dynamic unrest. A historical example of slope instability is the landslide which occurred in 1988 along the northwestern flank of La Fossa Cone on the island of Vulcano (Aeolian Archipelago). Based on this past activity, a susceptibility assessment using the bivariate technique of the GIS matrix method (GMM) was carried out on the islands of Lipari and Vulcano. Nevertheless, this case is congruent with those where a part of the surface was not assigned to stable or unstable areas, since a comprehensive inventory was only available for the island of Lipari. Some of the implemented steps of the susceptibility matrix method were modified to enable the model developed in the Lipari area to be applied to both islands. Considering the important role that the classification of conditioning factors plays in susceptibility analysis, the degree of association with landslide spatial distribution for the multiple classifications of each factor was assessed. Furthermore, an innovative clustering approach based on text and data mining techniques (self-organizing map neural network) was applied and compared with a heuristic classification of the categorical variable of lithology units. In addition to the extensive contingency analysis, up to 14 factor combinations were submitted to the GMM, validated and compared so as to select the one that best explains the susceptibility zoning. The effects of these incorporated processes in the previous phase of classification were discussed and preliminary susceptibility map was generated for both islands. After the validation of the susceptibility assessment, it is shown that the highest classes (High and Very High) matched 76.9% (relative accuracy) of the test inventory, while the lower susceptibility classes (Very Low and Low) resulted in a degree of fit of 14.39% (relative error).
    Beschreibung: Published
    Beschreibung: 969–982
    Beschreibung: 6V. Pericolosità vulcanica e contributi alla stima del rischio
    Beschreibung: JCR Journal
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 7
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    Unsteady magma discharge during the “El Retiro” subplinian eruption (Turrialba volcano, Costa Rica): Insights from textural and petrological analyses (2020)
    Elsevier
    Details
    Publikationsdatum: 2020-03-06
    Beschreibung: Turrialba is an active volcano of the Cordillera Volcánica Central in Costa Rica, which is currently experiencing a renewal of the eruptive activity after ~150 years of eruptive quiescence. Because of its explosive eruptive records in the recent geological history and the proximity with the metropolitan area of San José, this volcano poses serious threats to the population and economy of the area. In this study, we investigated the andesitic products of an explosive event (VEI 4) that occurred at Turrialba volcano ~2 ka, which we referred to as “El Retiro” eruption. Results fromfield observations, textural and chemical analyses indicate that the El Retiro eruptionwas characterized by two main pulses separated by a low energy activity. The eruption was fed by a homogeneous andesitic magma batch that crystallized along a P-T path of 0.1–400 MPa and 1050–1145 °C. The vesicle number density of pumiceous clasts ranges between 107 and 108 cm−3, in agreement with previous data from subplinian eruptions. The magma batch underwent decompression rates and pre-fragmentation velocities of 0.40–0.95 MPa s−1 and 23–37 m s−1, respectively. A marked textural variability within each stratigraphic layer has been also observed. This potentially suggests a horizontal zonation of the magma column, a condition that may have induced velocity gradients and high viscosity contrasts in the conduit leading to magma fragmentation. The observed pulsating behavior translates into mass eruption rate fluctuations that can be related to changes in magma volatile contents. Further explosive eruptions with characteristics similar to those observed for El Retiro, cannot be excluded at Turrialba volcano. This denotes the importance of investigating eruption dynamics at the conduit, providing key information to rigorously assess the volcanic risk in populated areas.
    Beschreibung: Published
    Beschreibung: 101-115
    Beschreibung: 3V. Proprietà chimico-fisiche dei magmi e dei prodotti vulcanici
    Beschreibung: JCR Journal
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 8
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    The 2011 unrest at Katla volcano: seismicity and geological context (2020)
    Details
    Publikationsdatum: 2020-04-14
    Beschreibung: Katla is one of the most active volcanoes in Iceland and is characterised by persistent seismicity. It is partly covered by the Mýrdalsjökull glacier and its historic activity is dominated by phreatomagmatic eruptions within the caldera associated with catastrophic glacial floods. In July 2011 a sudden jökulhlaup was released from the glacier, associated with tremor, elevated seismicity inside the caldera and a new cluster of seismicity on the south flank. This was likely caused by a hydrothermal or magmatic event, possibly a small subglacial eruption. Similar unrests occurred in 1955 and 1999. We have identified changes of the seismicity pattern coinciding with the 2011 unrest, suggesting a modification in the volcanic system. It may be speculated that if the persistent seismicity at Katla is an indication of a pressurized magma system ready to erupt, small events like those of 1955, 1999 and 2011 may trigger larger eruptions in the future. We have also conducted a pilot study of the geology of the southern flank, where the new seismicity is recorded, and identified sources for flank eruptions in the recent eruptive history of Katla. These include rhyolitic domes and surtseyan craters. Therefore, a wide range of volcanic processes have to be taken into account as possible source for the new seismicity and volcanic hazard.
    Beschreibung: Published
    Beschreibung: 53-70
    Beschreibung: 2T. Deformazione crostale attiva
    Beschreibung: JCR Journal
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 9
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    Multi-stage formation of La Fossa Caldera (Vulcano Island, Italy) from an integrated subaerial and submarine analysis (2020)
    Details
    Publikationsdatum: 2020-05-26
    Beschreibung: The analysis of multibeam bathymetry, seismic profiles, ROV dive and seafloor sampling, integrated with stratigraphic and geological data derived from subaerial field studies, provides information on the multi-stage formation and evolution of La Fossa Caldera at the active volcanic system of Vulcano (Aeolian Islands). The caldera is mostly subaerial and delimited by well-defined rims associated to three different collapse events occurred at about 80, 48–24, and 13–8 ka, respectively. The NE part of the caldera presently lies below the sea-level and is delimited by two partially degraded rim segments, encompassing a depressed and eroded area of approximately 2 km2. We present here further morphological and petrochemical evidence linking the subaerial caldera rims to its submarine counterparts. Particularly, one of the submarine rims can be directly correlated with the subaerial eastern caldera border related to the intermediate (48–24 ka) collapse event. The other submarine rim cannot be directly linked to any subaerial caldera rim, because of the emplacement of the Vulcanello lava platform during the last 2 millennia that interrupts the caldera border. However, morphological interpretation and the trachyte composition of dredged lavas allow us to associate this submarine rim with the younger (13–8 ka) caldera collapse event that truncated the trachyte-rhyolite Monte Lentia dome complex in the NW sector of Vulcano. The diachronicity of the different collapse events forming the La Fossa Caldera can also explain the morpho-structural mismatch of some hundreds of meters between the two submarine caldera rims. A small part of this offset could be also accounted by tectonic displacement along NE–SW trending lineaments breaching and dismantling the submarine portion of the caldera. A network of active erosive gullies, whose headwall arrive up to the coast, is in fact responsible of the marked marine retrogressive erosion affecting the NE part of the caldera, where remnants of intra-caldera volcanic activity are still evident. Submarine morphological features associated to the entrance of subaerial lava flow units into the sea are presented, particularly related to the construction of the La Fossa Cone and Vulcanello. More generally, this study demonstrates the utility of integrated marine and subaerial studies to unravel the volcano-tectonic evolution of active insular volcanoes.
    Beschreibung: Published
    Beschreibung: 479–492
    Beschreibung: 1V. Storia eruttiva
    Beschreibung: JCR Journal
    Schlagwort(e): 04.04. Geology ; 04.08. Volcanology ; 04.02. Exploration geophysics
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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  • 10
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    (Garnet)-spinel peridotite xenoliths from Mega (Ethiopia): Evidence for rejuvenation and dynamic thinning of the lithosphere beneath the southern Main Ethiopian Rift (2018)
    Details
    Publikationsdatum: 2018-05-04
    Beschreibung: Petrological and geothermobarometric data from (garnet)-spinel peridotite and pyroxenite xenoliths in Quaternary alkali-basalts at Mega (Sidamo region, Ethiopia) provide evidence for refertilization and thinning of the lower subcontinental lithospheric mantle (SCLM) during Tertiary rifting events in the southern Main Ethiopian Rift (MER). Samples of lherzolites, harzburgites, and olivine websterites contain spinel-pyroxene symplectites thatwere formed by garnet breakdown reactions. P-T equilibration conditions, in part calculated using the reconstructed garnet composition (pyrope), indicate the evolution of peridotites from the P-T conditions fromthe garnet stability field (2.9–2.2 GPa; 945–1025 °C), through garnet-spinel transition (b 2.1–1.7 GPa at 906–1017 °C), to the final equilibration in the spinel stability field (1.3 GPa at 862–1056 °C), corresponding to a nearly adiabatic decompression path of about 50 km. Peridotite chemical compositions plot in an off-craton trend, with variable fertility degrees, only in part due to partial melting processes. Rocks showvariable CaO contents (0.96–4.12 wt%), CaO/Al2O3 ratios (1.42–4.46), and clinopyroxene contents (6–31 vol.%), reaching compositions more enriched than pyrolite. Clinopyroxene shows evident LREE, U, Th, and Sr enrichments, particularly in harzburgites. Geochemical data suggest heterogeneous refertilization of a refractory lower SCLM, induced by infiltration and migration through porous flow of silicate-carbonate melts. Metasomatic processes drove melt compositions towards low-viscosity highly-mobile C-O-H-richmelts, inducing cryptic and hydrousmodalmetasomatismin refractory peridotites. Heterogeneous refertilization of the SCLM beneath the southern MER seems to have been induced by upwelling of asthenospheric melts and/or by reactivation of ancient lithospheric metasomes. Rejuvenation processes could have rheologically weakened the base of SCLM through gravitational instabilities, and increased the extensional stresses, causing a destabilizing effect at the onset of the lithospheric thinning and Tertiary rifting.
    Beschreibung: Published
    Beschreibung: 231-248
    Beschreibung: 1T. Deformazione crostale attiva
    Beschreibung: 7T. Struttura della Terra e geodinamica
    Beschreibung: JCR Journal
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
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