New findings of Late Glacial Etna pumice fall deposits in NE Sicily and implications for distal tephra correlations in the Mediterranean area

Pumice fall deposits found in the Nebrodi
Mountains and along the Alcantara River, close to the town
of Randazzo (NE Sicily), have been studied to derive information
about their volcanic source and age. The geochemical
Na-alkaline affinity of juvenile products, benmoreite to trachyte,
clearly indicates they originated from Etna volcano
(Sicily). Major (EMPA) and trace (LA-ICP-MS) element
compositional data on matrix glasses indicate that the investigated
deposits have a compositional affinity consistent with
the tephra deposits of unit D produced by the Ellittico calderaforming
eruptions between ca. 17 and 19 cal ka BP.
Furthermore, their compositions correspond to the distal tephra
equivalent found in some lacustrine and marine cores in
Central Italy (Y-1, TM-11), Tyrrhenian Sea (Et-1; MD10α)
and Adriatic Sea (Pal94-66-358; Pal94-8-353). We applied
the principal components analysis (PCA), a statistical tool able
to reduce the variability of a complex system, to compare the
compositions of the proximal samples with the possible distal
counterparts found in drill cores of the Mediterranean area. On
the basis of northward dispersal of the studied deposits and
their geochemical features, we suggest they represent a
previously unreported sub-Plinian/Plinian eruption of
Ellittico volcano producing medial-distal pumice fall deposits
in the Nebrodi Mountains and close to Randazzo, named
here the D1c layer. The discovery of these deposits helps
solve the problem of distal correlations of the northerly
dispersed tephra from Etna related to unit D, for which
no definitive attribution with proximal units was given in
previous studies. The results presented here add to the
knowledge of the eruptive history of the volcano and contribute
to expanding the proximal geochemical glass
dataset for distal tephra correlation in the Mediterranean
region during the Late Glacial period.