Although the oldest volcanic rocks exposed atPantelleria (Strait of Sicily) are older than 300 ka, most ofthe island is covered by the 45–50 ka Green Tuffignimbrite, thought to be related to the Cinque Denticaldera, and younger lavas and scoria cones. Pre-50 karocks (predominantly rheomorphic ignimbrites) are exposedat isolated sea cliffs, and their stratigraphy and chronologyare not completely resolved. Based on volcanic stratigraphyand K/Ar dating, it has been proposed that the older LaVecchia caldera is related to ignimbrite Q (114 ka), and thatignimbrites F, D, and Z (106, 94, and 79 ka, respectively)were erupted after caldera formation. We report here thepaleomagnetic directions obtained from 23 sites in ignimbriteP (133 ka) and four younger ignimbrites, and from anuncorrelated (and loosely dated) welded lithic breccia thoughtto record a caldera-forming eruption. The paleosecularvariation of the geomagnetic field recorded by ignimbrites isused as correlative tool, with an estimated time resolution inthe order of 100 years. We find that ignimbrites D and Zcorrespond, in good agreement with recent Ar/Ar agesconstraining the D/Z eruption to 87 ka. The welded lithicbreccia correlates with a thinner breccia lying just belowignimbrite P at another locality, implying that collapse of theLa Vecchia caldera took place at ~130–160 ka. This calderawas subsequently buried by ignimbrites P, Q, F, and D/Z.Paleomagnetic data also show that the northern calderamargin underwent a ~10° west–northwest (outwards) tiltingafter emplacement of ignimbrite P, possibly recording magmaresurgence in the crust.
|Numero di pagine||17|
|Rivista||Bulletin of Volcanology|
|Stato di pubblicazione||Published - 2012|
All Science Journal Classification (ASJC) codes
- Geochemistry and Petrology