Aprile 2022

PubAIV 2022
(aggiornamento di Aprile 2022)

1) Magmi e sistemi di alimentazione (1 articolo)
2) Dinamiche eruttive e di messa in posto (0 articoli)
3) Geologia e struttura dei vulcani (1 articolo)
4) Monitoraggio, pericolosità e rischio vulcanico (1 articolo)

Tematica 1: Magmi e sistemi di alimentazione
Caracciolo A., Halldórsson S.A., Bali E., Marshall E.W., Jeon H., Whitehouse M.J., Barnes J.D., Guðfinnsson G.H., Kahl M., Hartley M.E. (2022)
Oxygen isotope evidence for progressively assimilating trans-crustal magma plumbing systems in Iceland.
Data di pubblicazione: 11/04/2022
PubAIV-ID-00063 - Articolo in Rivista (open access)

The oxygen isotope composition of mantle-derived melts can place important constraints on how magmas are processed as they traverse the crust. Assimilation of crustal material is a crucial aspect of basalt petrogenesis, as it affects the chemical and rheological characteristics of eruptive magmas at active volcanoes. We report oxygen isotope (δ18O) and trace element (TE) data from a suite of well-characterized basaltic melt inclusions and groundmass glasses from the Bárðarbunga volcanic system in Iceland to assess how and where in the plumbing system crustal rocks interact with ascending magmas. While both melt inclusions and groundmass glasses record a large range in δ18O values (+3.2‰ to +6.4‰ and +2.6‰ to +5.5‰, respectively) groundmass glasses record lower values on average. Relationships between incompatible trace element (e.g., Zr/Nb) and oxygen isotope ratios are best explained with three-component mixing, where primary melts derived from depleted and enriched mantle components with distinct δ18O values mix and acquire a low-δ18O character upon progressive contamination with altered Icelandic crust. The majority (60%) of melt inclusions require 10–30% exchange of oxygen with the Icelandic crust. In addition, for the first time, we link the extent of oxygen isotope exchange with melt equilibration depths, showing that most of the contamination occurs at 1–2 kbar (3–7 km depth). We propose that a progressively assimilating, multi-tiered plumbing system is a characteristic feature of the Bárðarbunga volcanic system, whereby chemical modifications resulting from interaction with the crust systematically increase as melts migrate through higher crustal levels. We show that similar processes may also occur across the active rift zone in Iceland.
Tematica 2: Dinamiche eruttive e di messa in posto
Tematica 3: Geologia e struttura dei vulcani
Risica G., Di Roberto A., Speranza F., Del Carlo P., Pompilio M., Meletlidis S., Todrani A. (2022)
Reconstruction of the subaerial Holocene volcanic activity through paleomagnetic and 14C dating methods: El Hierro (Canary Islands).
Journal of Volcanology and Geothermal Research, 425, 107526
Data di pubblicazione: 11/03/2022
PubAIV-ID-00061 - Articolo in Rivista (non-open access)

Volcanic hazard assessment relies on the accurate knowledge of the eruptive style and recurrence of volcanic eruptions in the past. At El Hierro (Canary Islands) historical and prehistorical records are still poorly defined, and although the island was the location of one of the most recent eruptions (La Restinga, 2011 CE) of the Canarian archipelago, the recent subaerial volcanism is still poorly studied. Information about the age of Holocene
volcanic activity as well as the stratigraphy of the deposits is scarce: few eruptions are dated so far, whereas the others are classified as pre-or Holocene events considering lava flow characteristics along the coast.
Here, we report on the dating of eleven (M˜na Chamuscada, M˜na del Tesoro, Orchilla, Las Calcosas, M˜na Negra, Lomo Negro, Below Lomo Negro, Cuchillo del Roque, Malpaso Member, and M˜na del Guanche) Holocene subaerial
eruptions, distributed along the three rift zones, combining paleomagnetic and 14C methods. We also provide geochemical analyses for nine of them. Results indicate that M˜na Chamuscada and M˜na del Tesoro occurred more recently than previously considered, setting them within the last two thousand years. Conversely, paleomagnetic and 14C ages found for Lomo Negro eruption are consistent with literature data (Villasante-Marcos and Pav´on-Carrasco, 2014) and constrain the occurrence of this event in the XVI century CE. Finally, for
Malpaso Member deposits, the two 14C datings obtained by charcoals found below and above the trachytic layer set the eruption during the Holocene epoch, between ~7300 BCE and ~4700 BCE. For the other eruptions, in
two cases (Orchilla and Las Calcosas) many possible time windows during the last 14 ka have been found, whereas a few possible ages have been obtained for the others. On the whole, the resulting chronological reconstruction of the recent activity of El Hierro indicates that eruptions occurred unevenly along the three main rifts, with nine eruptions in the WNW rift, six in the NE rift, and four in the SSE rift. We document at least two periods characterized by high eruptive frequency: an old one, between 8000 BCE and 1000 BCE, with eight
eruptions, three of which characterized by more evolved compositions (phonotephrite and trachyte), and a recent one, between 1000 BCE and present day, with at least seven eruptions, mainly showing basanite compositions. The new data yield a significant improvement of Holocene eruption chronology, thus are instrumental for a correct evaluation of the volcanic hazard at El Hierro.
Tematica 4: Monitoraggio, pericolosità e rischio vulcanico
Monaco L., Palladino D.M., Albert P.G., Arienzo I., Conticelli S., Di Vito M., Fabbrizio A., D'Antonio M., Isaia R., Manning C.J., Nomade S., Pereira A., Petrosino P., Sottili G.,  Sulpizio R., Zanchetta G., Giaccio B. (2022)
Linking the Mediterranean MIS 5 tephra markers to Campi Flegrei (southern Italy) 109–92 ka explosive activity and refining the chronology of MIS 5c-d millennial-scale climate variability.
Global and planetary Change, 211, 103875
Data di pubblicazione: 04/04/2022
PubAIV-ID-00062 - Articolo in Rivista (non-open access)

Explosive activity preceding the ~40 ka Campanian Ignimbrite (CI) eruption in the Neapolitan volcanic area, Southern Italy, has long been speculated based on the occurrences of widespread tephra layers, with a Campanian geochemical signature, such as the C-22, X-5, and X-6, preserved in Mediterranean Marine Isotope Stage (MIS) 5 sedimentary records. However, previous studies of pre-CI pyroclastic units occurring in close proximity of the Neapolitan volcanoes, including Campi Flegrei, Somma-Vesuvius, Ischia and Procida islands, did not allow a conclusive identification of the near-source equivalents of these tephra markers. Here we present a comprehensive characterization of four pyroclastic units from the Campanian Plain, comprising major and trace element glass compositions, Srsingle bondNd isotopes and 40Ar/39Ar dating. Our data allowed the identification of the medial equivalents of the MIS 5 tephra markers, including the widespread C-22, X-5, and X-6 tephra, and their assignment to previously undocumented Campi Flegrei activity between 109 and 92 ka. In addition to substantially extending Campi Flegrei explosive activity deeper in time, and thus providing the basis for a revaluation of its history, our findings provide new precise radioisotopic dating to better constrain the chronology of the millennial scale climatic oscillations of the MIS 5c-d in the Mediterranean area and possibly on a larger scale.
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