HOLOCENE TO PLEISTOCENE TEPHROCHRONOLOGY OF ELEVEN MARINE SEDIMENT CORES FROM THE AEGEAN SEA

In the complex marine setting around the upper Quaternary volcanic islands of the southeast Aegean Sea, the Marine Geological Unit of Athens University, Greece, recently recovered 43 cores. This project focuses on 11 cores (PAG-12-8, PAG-12-9, PAG-12-10, PAG-12-11, PAG-12-13, M-22-103, M-15-150, LC-21, PAG-155, SAR-14, and BE-10 ) retrieved from around the islands of Nisyros, Yali, Pyrgousa and Kos. These cores have been examined in detail for magnetic susceptibility and carbonate content with selective measurements of XRD bulk mineralogy and organic content. Based largely on magnetic susceptibility and smear slides, 26 intervals have been sampled for tephra.

Tephra grains in the 26 marine samples and one terrestrial reference sample are being analyzed in the electron microprobe laboratory at Concord University for 11 major and minor elements: SiO₂, TiO₂, Al₂O₃, FeO, MnO, MgO, CaO, Na₂O, K₂O, P₂O₅, and Cl. Analyses have been completed for 16 samples to date. The glass geochemistry will allow for correlation of tephras between the cores and for the larger-scale identification of source events. Potential local sources include three volcanic islands (Kos, Nisyros, Yali) in the SE Aegean Sea volcanic Arc. The biggest Quaternary volcanic event in the Aegean region, the 161 ka Kos Plateau Tuff-(KPT), is also under consideration. Other potential candidate tephras, known from other cores in the Aegean, include Yali-2, Nisyros Upper Pumice, Minoan (Z2), Kalogeri tephra, Cape Riva (Y2), and Campanian Ignimbrite (Y5). We are currently compiling data on these candidates and other Mediterranean region reference tephras for comparison with tephras from the 11 cores.