The Lower Pleistocene Tephra Layers in the Crotone Marine Sequence of Southern Italy: Tracing Their Volcanic Source Area

At least three tephra layers, with ages around 2 Ma, crop out in the Pleistocene marine sequence of the Crotone basin, in southern Italy. We present the petrography and the mineral and glass chemistry of these layers, in order to correlate them with other Pleistocene sequences and, possibly, to identify the volcanic source(s). The oldest layer (a1) contains glass shards with homogeneous rhyolitic composition, together with crystals of ortho- and clinopyroxene, plagioclase and amphibole. The age, petrography and major elements’ glass composition allow for correlation with coeval tephra layers cropping out in the southern Apennines, near the town of Craco, in Valle Ricca, near Rome, and in the Periadriatic basin, in central Italy. Two other younger tephras (a3 and a4) can be distinguished by the absence of hydrous phases in a3 and the occurrence of biotite in a4. They show a higher variability in glass composition, which may be related to multiple volcanic sources. A fourth tephra of unknown position, but probably intermediate between a1 and a3, was also recognized. The volcanic source of the tephra layers was identified in a submerged paleo-arc in the central Tyrrhenian Sea, possibly corresponding to the Ventotene ridge. The paper also provides a dataset of glass trace elements’ composition for future correlations.