Age and geochemistry of tephra layers from Ischia, Italy: constraints from proximal-distal correlations with Lago Grande di Monticchio

Emma Tomlinson, Paul Albert, Sabine Wulf, Richard Brown, Victoria Smith, Jorg Keller, Giovanni Orsi, Anna Bourne, Martin Menzies

    Research output: Contribution to journalArticlepeer-review

    36 Downloads (Pure)

    Abstract

    Unraveling the eruptive history of the Island of Ischia (southern Italy) is problematic due to its burial, caldera collapse, resurgent uplift and erosion. Here, we present new major and trace element glass data for 39–75 ka proximal tephra deposits, including those of the caldera-forming Monte Epomeo Green Tuff (MEGT) eruption. Correlations with the distal tephra archive preserved at Lago Grande di Monticchio (LGdM) are used to constrain the timing of as yet undated eruptive events. Out of 13 LGdM tephras analysed from the 39–104 ka time window, glass geochemical data show that all are compositionally consistent with the explosive volcanic eruptions of Ischia, whilst 5 of them can be correlated with specific proximal deposits.

    Pre-MEGT pyroclastic sequences comprise three compositional groups, these groups occur repeatedly in sucessive eruptions. Proximal-distal correlations indicate that the Porticello eruption occurred at 59 ± 2 ka and the Tisichiello eruption probably occurred at 76 ± 3 ka. The MEGT eruption is correlated with LGdM TM-19, which has been directly dated at 55 ± 2 ka. Post-MEGT tephras form compositional groups that overlap with the pre-MEGT but are displaced to lower FeO and TiO2 and lower incompatible element contents. Proximal-distal correlations indicate that the Schiappone and Pietre Rosse eruptions occurred at 50.6 ± 2.0 ka and 45 ± 6 ka, respectively.

    Tephra from the MEGT eruption span a wide compositional range, broadly overlapping the three pre-MEGT compositional groups but are displaced to higher Nd and Y and contain an additional less evolved glass population. Glass geochemistry is used to recognise and confirm distal equivalents of the MEGT at LGdM (TM-19) and in the Ionian (Y-7), Adriatic (PRAD 1870) and Tyrrhenian (C-18, MD 28) seas. Distal occurences of MEGT tephra define a dispersal axis to the south-southeast and are found as far as 540 km from Ischia, making the MEGT one of the most widely dispersed late Quaternary pyroclastic deposit erupted in the Campanian region. We estimate a volume of approximately 40 km3 for the fallout portion of the MEGT pyroclastic sequence on the basis of proximal and distal deposit thicknesses.
    Original languageEnglish
    Pages (from-to)22-39
    Number of pages18
    JournalJournal of Volcanology and Geothermal Research
    Volume287
    Early online date19 Sept 2014
    DOIs
    Publication statusPublished - 15 Oct 2014

    Keywords

    • tephrochronology
    • volcanic ash
    • Ischia
    • explosive eruptions
    • Quaternary volcanism
    • Campanian volcanic area
    • UKRI
    • NERC
    • NE/E015905/1

    Fingerprint

    Dive into the research topics of 'Age and geochemistry of tephra layers from Ischia, Italy: constraints from proximal-distal correlations with Lago Grande di Monticchio'. Together they form a unique fingerprint.

    Cite this