A potential early middle Pleistocene tephrostratotype for the Mediterranean basin: the Vallo Di Diano, Campania, Italy

A 207-m-long core was taken from the deposits of a paleolake formed in the Vallo di Diano tectonic basin of the southern Apennines, Italy. Fourteen major tephra beds were identified and distributed into three groups based on stratigraphic position, and chemical and mineralogical compositions. In a pilot dating program, glass ages were determined for three of these layers using the 40Ar/39Ar method; two of those layers produced discordant step-heating spectra and provided anomalously old ages. A third layer produced a well-defined plateau age of 0.596±0.006 Ma (2σ) and from its stratigraphic position, is correlated to oxygen isotope (δ18O) stage 15 of the deep-sea record. The climatic history of the paleolake can be interpreted from down-core pollen and δ18O variations, which show a succession of two glacial–interglacial cycles. Extrapolation of ages from the astronomically tuned deep-sea δ18O record to that of the paleolake indicates that the lake existed for almost 0.2 Ma. Potential eruptive source regions for the tephra layers include the Roman Volcanic Province, Roccamonfina and perhaps Mt. Vulture. While further dating is needed, the Vallo di Diano section provides valuable information on Middle Pleistocene climate history for the central Mediterranean region and offers a comparison of terrestrial environmental history to those preserved in marine records.