Please use this identifier to cite or link to this item: http://hdl.handle.net/2122/4532
AuthorsBrown, R.* 
Orsi, G.* 
De Vita, S.* 
TitleNew insights into Late Pleistocene explosive volcanic activity and caldera formation on Ischia (southern Italy)
Issue DateMar-2008
Series/Report no.5/70(2008)
DOI10.1007/s00445-007-0155-0
URIhttp://hdl.handle.net/2122/4532
KeywordsPyroclastic stratigraphy
Explosive volcanism
Caldera collapse
Ischia
Late Pleistocene
Subject Classification04. Solid Earth::04.08. Volcanology::04.08.99. General or miscellaneous 
04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks 
AbstractA 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 considerably more volcanically active than previously thought. Numerous vents were probably active during this period. The deposits of at least 10 explosive phonolite to basaltictrachyandesite 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 unknown 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 flowunits, separated by volcaniclastic sediments that were deposited during a pause in the eruption. Extracaldera deposits 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

Files in This Item:
File Description SizeFormat 
BroOrs-08.pdf1.91 MBAdobe PDFView/Open    Request a copy
Show full item record

Page view(s)

108
checked on May 27, 2017

Download(s)

25
checked on May 27, 2017

Google ScholarTM

Check

Altmetric