 |
| Titel |
Stratigraphy and eruption history of pre-Green Tuff peralkaline welded ignimbrites, Pantelleria, Italy |
| VerfasserIn |
Nina Jordan, Michael Branney, Rebecca Williams, Mike Norry |
| Konferenz |
EGU General Assembly 2013
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250073705
|
|
|
|
|
|
| Zusammenfassung |
| A revised volcanic stratigraphy is presented for the ignimbrites of Pantelleria, a
peralkaline caldera volcano situated in the submerged continental rift between Africa
and Sicily. The volcano has been active for -¥325Â ka (Mahood & Hildreth, 1986),
producing eight major ignimbrites from large central eruptions, which appear to have
alternated with numerous minor pumice falls and lavas from scattered local centres.
The main ignimbrites can be traced along superb coastal exposures and have been
logged in detail. Eruption-units have been defined by the position of palaeosols and a
type section designated. Lithic breccias and pumice fall deposits associated with
these major ignimbrites are interpreted as part of the same eruption overcoming
correlation problems encountered by previous workers (cf Mahood & Hildreth,
1986).
The ignimbrites are 2 to >20Â m thick, welded to rheomorphic and cover most of the
island, recording devastating, radial, high-temperature density currents. Five of the eight
major ignimbrites contain lithic breccias, which have commonly been interpreted as
recording caldera collapse events, but the details of individual calderas are not clear. The
ignimbrites were erupted between 181 and 50Â ka suggesting that the early history of the
island (325 to 181Â ka) differs from later stages in that only local pumice and lava-producing
eruptions have occurred. This means that the amount of erupted magma increased in the later
stage as the ignimbrites represent eruptions of many times the volume of the local
centres.
Distal peralkaline tephras have been found around the Mediterranean as far away as
~1200Â km. With only this volcano erupting peralkaline compositions, it suggests that
eruptions from Pantelleria have had a substantial impact on their environment. We infer that
there were few Plinian events on the island, and that the distal tephras may be co-ignimbrite
ashfall deposits.
REFERENCES: Mahood, G.A., Hildreth, W., (1986) Bulletin of Volcanology 48,
143-172. |
|
|
|
|
|
|