Vittorio Zanon

University of the Azores | UAc · IVAR - Instituto de Investigação em Vulcanologia e Avaliação de Riscos

Among the volcaniclastic products of melilitite-carbonatite eruptions, pelletal lapilli are often found, resulting in them being particularly useful for characterising the interface between the erupting magma and its volatile component. Pelletal lapilli, which were erupted during the most recent melilitite-carbonatite volcanic activity of the Mt. V...

The determination of the physical properties of volcanic rocks is essential to accurately define the character of an eruption as well as the geothermal potential of a specific area. The pores of volcanic rocks with distinct textures from Fogo volcano (also known as Água de Pau, the Azores), namely three basalts (s.l.) and one trachyte, are assessed...

This study provides new mineral chemistry data together with micro‐thermometric measurements on fluid inclusions hosted in ultramafic xenoliths (lherzolite, wehrlite, and dunite) brought to the surface by the last Mt. Vulture volcano activity (140 ka; southern Italy), and fed by melilitite‐carbonatite magmas. Petrographic evidence and mineralogical...

Fluid inclusions (FI) entrapped in phenocrysts carried by Ocean Island Basalts (OIB) contain key information on volatiles' abundance and origin in their mantle sources. Here, we add new piece of knowledge to our understanding of volatile geochemistry in global OIB magmas, by presenting new noble gas (He-NeAr) and carbon (C) isotope results for oliv...

The Azores archipelago, situated east of the Mid-Atlantic Ridge, comprises volcanic islands arranged along sub-parallel spreading systems and rests on a thick oceanic crust. Magma is supplied directly from the roots of the volcanic systems. Located at or nearby the boundary between the crust and the mantle, they consist of mafic cumulates and mafic...

Some of the most CO2-rich magmas on Earth are erupted by intraplate ocean island volcanoes. Here, we characterise olivine-hosted melt inclusions from recent (< 10 ky) basanitic tephra erupted by Fogo, the only active volcano of the Cape Verde Archipelago in the eastern Atlantic Ocean. We determine H2O, S, Cl, F in glassy melt inclusions and recalcu...

Fluid inclusion microthermometry on olivines, clinopyroxenes, and amphiboles was used during a volcanic eruption, in combination with real-time seismic data and rapid petrographic observations, for petrological monitoring purposes. By applying this approach to the study of 18 volcanic samples collected during the eruption of Tajogaite volcano on La...

Volcanic islands evolve through complex interactions between volcano growth and surface processes. Climate changes impact the physical and chemical processes that drive weathering and denudation. While global paleoclimate has been extensively studied for the late Quaternary, elucidating the local climatic response to global forcing on such islands...

Alkaline mafic magmas forming intra-plate oceanic islands are believed to be strongly enriched in CO2 due to low-degree partial melting of enriched mantle sources. However, until now, such CO2 enhancement has not been verified by measuring CO2 degassing during a subaerial eruption. Here, we provide evidence of highly CO2-rich gas emissions during t...

The Azores region straddles the Mid-Atlantic Ridge and comprises volcanic islands and seamounts interspersed with non-magmatic oceanic basins arranged along subparallel slow-spreading systems. The cross-check of CO2-rich fluid inclusions barometry from lavas and tephras erupted during the last 20 ka with the sources of seismicity of the last 22 yea...

Long-lasting eruptions are of complex characterization and are typically associated with challenging risk assessment and crisis management due to the usual occurrence of multiple interacting hazards evolving at different temporal and spatial scales (e.g., lava, tephra, and gas). The 2021 Tajogaite eruption of Cumbre Vieja (La Palma) demonstrated ho...

Paleosols (PSs) contain valuable information about the climatic conditions under which they formed and constitute an outstanding archive of past weathering processes. Nevertheless, paleosol dating over most of the Quaternary remains challenging. Volcanic environments are unique sites for such purposes, as precise radiometric age determination can b...

To investigate unexplored areas and apply methodologies suitable for monitoring volcanic activity, a pioneer study was undertaken in the crater lagoon of Vila Franca do Campo Islet to identify possible CO 2 degassing zones in the marine environment. This study was carried out using a floating accumulation chamber, which to the best of our knowledge...

Understanding the pre-eruptive volatile contents in magmas is critical to charactering the magmatic plumbying systems that feed acative volcanoes, and is key to volcano monitoring and volcanic hazard assessment. Silicate melt inclusions (MIs) hosted in primitive minerals are a powerful tool to definite parental melt volatile contents, and to track...

El estudio petrográfico de los minerales de calcita en los diques carbonatíticos del Complejo Basal de Fuerteventura (Ajuy, Punta de la Nao) muestra la presencia de inclusiones fluidas primarias aisladas, corroborando su origen magmático más que un origen tardío. Los estudios microtermométricos en calcita muestran un intervalo de temperatura eutéct...

The architecture of the magma storage system underneath Fogo Volcano (Cape Verde archipelago) is characterised using novel fluid inclusion results from fifteen basanites, spanning the last 120 thousand years of volcanic activity, and encompassing a major flank collapse event at ~73 ka. Fluid inclusions, hosted in olivine and clinopyroxene, are made...

Plain Language Summary The study of fluid inclusions (FIs) (small amount of fluid trapped within minerals) provides important information on variable environments and magmatological processes in which the host minerals were formed. Investigation of the FIs with respect to their composition, trapping pressure and temperature, allow us to constrain m...

The Ribeira Grande geothermal field is located on the northern flank of Fogo Volcano (S. Miguel Island, Azores) and it is characterised by the presence of several active hydrothermal manifestations. An analysis of the RG5 geothermal well has been carried out by the recognition of neoformation minerals with depth and the estimation of equilibrium te...

Substantial terrestrial gas emissions, such as carbon dioxide (CO2), are associated with active volcanoes and hydrothermal systems. However, while fundamental for the prediction of future activity, it remains difficult so far to determine the depth of the gas sources. Here we show how the combined measurement of CO2 and radon-222 fluxes at the surf...

The petrographic analysis in calcite minerals in carbonatitic dykes from Fuerteventura Basal Complex (Ajuy, Punta de la Nao) shows the presence of isolated primary fluid inclusions, corroborating their magmatic origin instead of a late-stage origin. Micro-thermometric studies in calcite show a restricted range of apparent eutectic temperature (Te*=...

Oxygen fugacity (fO2) is a fundamental variable in igneous petrology with utility as a potential tracer of recycled high Fe⁺³/ΣFe surficial materials in the sources of mantle-derived lavas. It has been postulated that ocean island basalts (OIB) have elevated fO2 relative to mid-ocean ridge basalts (MORB) owing to higher average Fe⁺³/ΣFe in their so...

The magma storage system of Fogo Volcano, Cape Verde archipelago, was characterized by petrological, geochemical, and fluid inclusion studies. The analysed samples span the last 120 ky of activity, and include 3 extra-caldera samples ( ̴ 120 ka, ̴ 60 ka, and ̴ 10 ka) and 12 intra-caldera samples from 8 different eruptions ( ̴ 10 ka, 1664, 1785, 179...

A set of springs were sampled along São Miguel Island (Azores, Portugal) to proceed to the characterization of the major-ion and radon (222Rn) content. According to the selection criteria a total of 42 discharges were sampled, both during winter and summer periods, along major geological units, namely 3 springs at Sete Cidades Volcano, 4 at Nordest...

Oxygen fugacity (fO2) is a fundamental variable in igneous petrology with utility as a potential tracer of recycled surficial materials in the sources of mantle-derived lavas. It has been postulated that ocean island basalts (OIB) have elevated fO2 relative to mid-ocean ridge basalts (MORB) owing to more oxidized source regions. To clarify this iss...

The Pico-Faial ridge is a steep WNW-ESE volcanic ridge that has developed within the Nubia-Eurasia diffuse plate boundary, close to the Azores Triple Junction. The ridge comprises two islands, Pico and Faial, separated by a shallow (< 100 m depth) and narrow (< 8 km) channel. Despite some similarities, the two islands show contrasting features stil...

Clinopyroxenes from the Pico Volcano (Pico Island, Azores Archipelago) have been used as a proxy to define the water content of primitive magmas and the volcanological history of the erupted rocks. This very young volcano (53 ± 5 ka) is at a primordial stage of its evolution in comparison with the other volcanoes of the Azores. Clinopyroxenes from...

Quantification of the CO2 released by the volcanoes to the atmosphere is relevant for the evaluation of the balance between deep-derived, biogenic and anthropogenic contributions. The current study estimates the CO2 released from Furnas do Enxofre degassing area (Terceira Island, Azores archipelago) by applying an approach that integrates the flux...

A multidisciplinary approach combining petrological, geochemical, and fluid-inclusion studies with seismic monitoring data was used to build a model of the magma feeding system of Pico volcano (Azores islands, North Atlantic Ocean). We explore how magma has ascended to the surface in the last 10 ka and how this ascent is associated with the selecti...

Petrological and geochemical (major, trace, Sr-Nd isotope) data for recent (<5 kyr old) basalts that sporadically erupt on the western flank of Piton de la Fournaise (PdF), one of the most active volcanoes on Earth, allow the tracking of magma transfer and evolution from mantle to crustal depths. In the western peripheral area of PdF we document th...

Petrological and geochemical (major element, trace element, Sr-Nd isotope) data for recent (<5 kyr old) basalts that sporadically erupt on the western flank of Piton de la Fournaise (PdF), one of the most active volcanoes on Earth, allow the tracking of magma transfer and evolution from mantle to crustal depths. In the western peripheral area of Pd...

New highly siderophile element (HSE: Os, Ir, Ru, Pt, Pd, Re) abundance and Os isotopic compositions, along with major- and trace-element abundance and Sr-Nd-Hf-Pb isotope data are reported for high-MgO (>8–17 wt.%) lavas from the islands of São Miguel, Terceira, Pico and Faial in the Azores archipelago. The lavas span the range of Sr-Nd-Hf-Pb isoto...

Ocean island volcanoes are dynamic geological structures. Their shape changes rapidly as they evolve through complex interactions among eruptions, magma intrusions, tectonics, mass wasting and subaerial erosion. The central volcanoes of the Azores islands (North Atlantic Ocean) show a wide variety of morphologies, ranging from conical edifices to i...

Nowadays volcanic manifestations in the Azores archipelago are represented by several permanent gas emissions that include hydrothermal fumaroles, thermal and cold CO2-rich springs, as well as diffuse degassing areas. Visible manifestations of volcanism are found out in most of the islands and their isotopic imprints give clues both to understand t...

Among all eruptions that took place on the Azores Archipelago since the Portuguese settlement in the XVI century, those of 1580 and 1808 in the island of São Jorge were unusual. The magma erupted in 1580 ascended from at least 23 km and ponded at a minimum depth of 16 km. Here residual magma fractionated mafic phases and plagioclase during 228 year...

Our discovery of moissanite grains in a peralkaline syenite from the Água de Pau Volcano (São Miguel, Azores Islands, Portugal) represents the first report of this mineral in present day oceanic geodynamic settings. Raman spectroscopy and single-crystal X-ray diffraction show the presence of both the 6H and 4H polytypes with the predominance of the...

Gaseous elemental mercury (Hg⁰g or GEM) and CO2 are emitted from active hydrothermal systems in volcanic areas mostly through diffuse degassing. Here, data from about 400 simultaneous measurements of soil GEM and CO2 flux performed within the caldera of Furnas Volcano, São Miguel Island (Azores) are discussed for the first time. This survey aimed a...

The Lajes Ignimbrite on Terceira Island (Azores) records the last major pyroclastic density current-forming eruption of Pico Alto Volcano that occurred ca. 21kyrs ago. This comenditic trachyte ignimbrite contains up to 30vol% of crystals, mostly anorthoclase. Geochemical investigation of the products collected throughout two key outcrops reveals th...

Workshop Rhum-Rum 2016

Rhodoliths are a common producer of carbonates on modern and ancient shelves worldwide, and there is growing evidence that they thrive on volcanic insular shelves. However, little is still known on how rhodoliths cope with the demands of this particularly dynamic environment. In this study, the focus is placed on fossil rhodoliths from a Pliocene s...

In Earth Sciences there is a growing interest in studies concerning soil-radon activity, due to its potential as a tracer of numerous natural phenomena. Our work marks an advance in the comprehension of the interplay between tectonic activity, volcanic eruptions and gas release through faults. Soil-radon measurements, acquired on Mt. Etna volcano i...

The AD 1761 eruption on Terceira was the only historical subaerial event on the island and one of the last recorded in the Azores. The eruption occurred along the fissure zone that crosses the island and produced a trachybasalt lava flow and scoria cones. Small comenditic trachyte lava domes (known as Mistérios Negros) were also thought by some to...

Several processes concur to shape an oceanic volcanic island, in particular the insular shelves, but the dominant process will be the one with the highest rate for a given period of time. Therefore, one has to estimate rates in order to conclude for the dominant process. We take advantage of the contrasting tectonic settings of two islands in the A...

Magmas in the Azores (Portugal) were erupted from both fissure zones and central volcanoes during overlapping periods. Fissure zones follow extensional trends oriented accordingly with the regional tectonics, erupting basalts and hawaiites. Central volcanoes are characterized by transtensive tectonics and erupted basaltic to trachytic magmas. Highl...

Ponding conditions of basalts erupted from fissure zones at São Miguel Island (Azores) were investigated through microthermometry of fluid inclusions, hosted in olivines and clinopyroxenes, and whole-rock and mineral chemistry. The Região dos Picos and Achada das Furnas fissure zones formed between central volcanoes and erupted geochemically simila...

Massive fossil shell accumulations require particular conditions to be formed and may provide valuable insights into the sedimentary environments favouring such concentrations. Shallow-water shell beds appear to be particularly rare on reefless volcanic oceanic islands on account of narrow, steep and highly-energetic insular shelves where the poten...

Massive fossil shell accumulations require particular conditions to be formed and may provide valuable insights into the sedimentary environments favouring such concentrations. Shallow-water shell beds appear to be particularly rare on reefless volcanic oceanic islands on account of narrow, steep and highly-energetic insular shelves where the poten...

The mafic magmatism of the last 50 ka on Terceira Island, Azores archipelago, occurred along three segments of the fissure zone that crosses the island. The two subaerial segments developed with different trends over pre-existing, quiescent or extinct, central volcanoes. The Serreta submarine ridge is the offshore segment of the fissure zone which...

The hazard and risk posed by future effusive eruptions from the Éguas-Carvão fissure system in São Miguel Island (Azores Archipelago) is assessed. This fissure system, located ~ 13 km from the town of Ponta Delgada and its international airport, was the only site in the whole island to be characterized by recurrent basaltic eruptions over the past...

The Azores archipelago is located at the triple junction between the North American, African and Eurasian plates, in an area dominated by transtensive tectonic. The magmatism is concentrated along elongated volcanic ridges, generally orthogonal to the Mid Atlantic Ridge (MAR), where central volcanoes alternate with fissure zones. In order to better...

Lajes-Angra Ignimbrite (LAI) is the most recent (around 21 ka) caldera-forming event produced by Pico Alto volcano at Terceira Island (Azores). Lajes-Angra Ignimbrite Formation comprises two members closely spaced in time: Lajes and Angra. The Lajes member, the most widely distributed throughout the island, was sampled at two sites: 1) at Lajes (ty...

Lo studio riassume i risultati di una campagna di misure geochimiche e strutturali condotte nel 2004 (Neri et al., 2011) e riguarda la misurazione delle emissioni di gas radon e thoron dal suolo effettuate lungo il fianco orientale dell’Etna, in una zona caratterizzata dalla presenza di numerose faglie attive. Le elaborazioni statistiche effettuate...

The concept of an 'Azores mantle plume' has been widely debated, and the existence of an Azores hotspot questioned. In an effort to shed new light on this controversy, we present He isotope and major, trace and volatile element compositions for basaltic scoriae from five monogenetic cones emplaced along the fissure zone of Pico Island, the youngest...

Oceanic islands - such as the Azores in the mid-North Atlantic - are periodically exposed to large storms that often remobilize and transport marine sediments along coastlines, and into deeper environments. Such disruptive events create deposits – denominated tempestites – whose characteristics reflect the highly dynamic environment in which they w...

In the islands of Faial and Pico (the Azores), fluid inclusions are hosted in megacrysts of olivine (Mg#80–88) and clinopyroxene (Mg#79–90) in highly porphyritic lavas and in mineral assemblages of ultramafic xenoliths. Rare inclusions are contained in olivine phenocrysts (Mg# < 80) and plagioclases in poorly porphyritic lavas. Trails of late-stage...

Magmas in Faial Island, Azores (Portugal), were mostly erupted from two fissure zones and the Caldeira central volcano during overlapping periods. The fissure zones follow extensional trends oriented WNW and ESE and erupted nepheline- to hypersthene-normative basalts and hawaiites. The Caldeira central volcano builds the central part of the island,...

Azores intra-plate oceanic basalts are thought to be a typical example of hot-spot ridge interactions. Volatiles (in particular CO2 and H2O) represent key parameters at each step of magma production, differentiation and eruption. We report here the first complete data set on major, trace and volatile elements, together with He isotopes for basaltic...

The nine oceanic islands that comprise the Azores archipelago are located in the middle of the northern Atlantic Ocean. In this isolated archipelago, there is a rich fossil record in one of the islands, Santa Maria. In this island, samples were collected in the Upper Miocene composite section of Malbusca outcrop, located in the southern shore of th...

Between December 1998 and April 2001, a submarine basaltic eruption occurred west of Terceira Island, Azores (Portugal) in water depths between 300 and 1,000 m. Physical evidence for the eruption was provided by the periodic occurrence of hot lava “balloons” floating on the sea surface. The balloons consisted of a large gas-filled cavity surrounded...

Several mantle xenoliths from the island of Sao Miguel (Azores, Portugal) have been studied to investigate the nature of the mantle beneath the Azorean archipelago. Ultramafic xenoliths are porphyroclastic spinel harzburgite and subordinate clinopyroxene-poor lherzolite, range between 3 and 10 cm in size and show clear signs of plastic deformation....