The dating and correlation of an eastern Mediterranean lake sediment sequence : a 46–4 ka tephrostratigraphy for Ioannina (NW Greece)

Abstract

Terrestrial archives from the Mediterranean have been crucial to expanding our understanding of past environmental variability on a range of timescales. Dating Quaternary sequences in the Mediterranean is, however, often challenging, and age models often have large chronological uncertainties. Tephra deposits can provide crucial age control for detailed environmental reconstructions on sub-centennial timescales. Here, tephra analysis is undertaken for the first time on a sediment core (I-08) from Lake Ioannina, northwest Greece, for the interval spanning 46-4 ka bp. Detailed visible and 'crypto-' tephra analysis identifies deposits associated with explosive volcanism at Italian volcanic sources, including Campi Flegrei, Pantelleria, and the Aeolian Islands. We identify two visible tephra layers, the Campanian Ignimbrite (CI/Y-5; ca. 39.8 ka bp) and Pantelleria Green Tuff (PGT/Y-6; ca. 45.7 ka), as well as the Holocene Vallone del Gabellotto cryptotephra marker (VG/E-1; ca. 8.3 ka bp). Evidence for repeated remobilisation and redeposition of CI tephra material is outlined, and the potential mechanisms and effects of sediment reworking in lake environments are examined. Bayesian modelling, which incorporates the new tephra ages with earlier radiocarbon dates, extends the I-08 core chronology back to ca. 46 ka bp, facilitating direct correlation of the Ioannina sequence to others in the Mediterranean region.