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|Authors: ||Brown, R. J.*|
De Vita, S.*
|Title: ||New insights into Late Pleistocene explosive volcanic activity and caldera formation on Ischia (southern Italy)|
|Title of journal: ||Bulletin of Volcanology|
|Issue Date: ||2007|
|Keywords: ||Pyroclastic stratigraphy|
|Abstract: ||Abstract A new pyroclastic stratigraphy is presented for
the island of Ischia, Italy, for the period ∼75–50 ka BP. The
data indicate that this period bore witness to the largest
eruptions recorded on the island and that it was consider-
ably more volcanically active than previously thought.
Numerous vents were probably active during this period.
The deposits of at least 10 explosive phonolite to basaltic-
trachyandesite eruptions are described and interpreted.
They record a diverse range of explosive volcanic activity
including voluminous fountain-fed ignimbrite eruptions,
fallout from sustained eruption columns, block-and-ash
flows, and phreatomagmatic eruptions. Previously un-
known eruptions have been recognised for the first time
on the island. Several of the eruptions produced pyroclastic
density currents that covered the whole island as well as the
neighbouring island of Procida and parts of the mainland.
The morphology of Ischia was significantly different to that
seen today, with edifices to the south and west and a
submerged depression in the centre. The largest volcanic
event, the Monte Epomeo Green Tuff (MEGT) resulted in
caldera collapse across all or part of the island. It is shown
to comprise at least two thick intracaldera ignimbrite flow-
units, separated by volcaniclastic sediments that were
deposited during a pause in the eruption. Extracaldera de-
posits of the MEGT include a pumice fall deposit emplaced
during the opening phases of the eruption, a widespread
lithic lag breccia outcropping across much of Ischia and
Procida, and a distal ignimbrite in south-west Campi Flegrei.
During this period the style and magnitude of volcanism was
dictated by the dynamics of a large differentiated magma
chamber, which was partially destroyed during the MEGT
eruption. This contrasts with the small-volume Holocene
and historical effusive and explosive activity on Ischia, the
timing and distribution of which has been controlled by the
resurgence of the Monte Epomeo block. The new data
contribute to a clearer understanding of the long-term
volcanic and magmatic evolution of Ischia.|
|Appears in Collections:||Papers Published / Papers in press|
04.08.05. Volcanic rocks
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