Paleomagnetic dating of the most recent silicic eruptive activity at Pantelleria (Strait of Sicily)

We report on the paleomagnetism of ten sites in
the products of the most recent silicic eruptive cycle of
Pantelleria, Strait of Sicily. Previously radiometrically dated
at 5–10 ka, our comparison with proxies for geomagnetic
field directions allows us to narrow considerably the time
window during which these eruptions occurred. The
strongly peralkaline composition causes the magmas to
have low viscosities, locally resulting in strong agglutination
of proximal fall deposits. This allows successful
extraction of paleomagnetic directions from the explosive
phases of eruptions. One of our sites was located in the
Serra della Fastuca fall deposit, produced by the first
explosive event of the eruptive cycle. The other nine sites
were located in the most recent explosive (pumice fall and
agglutinate from Cuddia del Gallo and Cuddia Randazzo)
and effusive (Khaggiar lava) products. The (very similar)
paleomagnetic directions gathered from eight internally
consistent sites were compared to reference geomagnetic
field directions of the last 5–10 ka. Directions from Cuddia
del Gallo agglutinate and Khaggiar flows translate into 5.9-
to 6.2-ka ages, whereas the Fastuca pumices yield a slightly
older age of 6.2–6.8 ka. Hence, the most recent silicic
eruptive cycle lasted at most a millennium and as little as a
few centuries around 6.0 ka. Paleomagnetically inferred
ages are in good agreement with published (and calibrated
by us) 14C dates from paleosols/charcoals sampled below
the studied volcanic units, whereas K/Ar data are more
scattered and yield ∼30% older ages. Our data show that the
time elapsed since the most recent silicic eruptions at
Pantelleria is comparable to the quiescence period separating
the two latest volcanic cycles.