Cyclic climatic records during the Olduval subchron (Uppermost Pliocene) on Zakynthos Island (Ionian Sea)

Abstract

This contribution is focused on a high-resolution cyclostratigraphic investigation by means of an integrated study on the deposits on Zakynthos island (Ionian sea) within the Olduvai polarity subchron (from 1.95 to 1.77 Ma). Accurate palaeomagnetic study has been carried out to specify the precise position of the Olduvai subchron in the Zakynthos city series, named “Citadel” section. New detailed lithological observations have pointed out the presence of turbiditic and laminated facies within clay deposits. Layers corresponding to the Olduvai subchron have been studied in detail for pollen analysis and CaCO 3 content in order to evidence responses to the glacial/interglacial cycles. Four climatic cycles have been recognized by pollen and CaCO 3 analyses. In order to achieve a correct correlation with the isotopic stages, the δ 18O measurements of the Zakynthos's foraminifer Globigerinoides ruber have been provided; they reveal the Artemisia expansions (e.g. steppes) to be contemporaneous with interglacial phases. This behaviour does not conform to the previously evidenced responses of plant associations (especially Artemisia) to the glacial cycles in the western Mediterranean. Hence, the “west Mediterranean model” cannot be upheld for the whole Mediterranean domain.