Paleoclimatic significance of the Pliocene Amphistegina levels from the Tyrrhenian margin of Central Italy

Two distinct Amphistegina-rich intervals are recognized within the Pliocene succession of Umbria and Latium, referred respectively to the Piacenzian and to the Gelasian; these deposits represent the last warm peaks before the strong Late Pliocene climatic deterioration. The investigated foraminiferal assemblages, characterized by specimens provisionally identified as Amphistegina targionii (Meneghini), testify to shallow, relatively warm and oligotrophic waters, according to the regressive trend caused by the regional uplift affecting the Tyrrhenian margin from Messinian to Early Pleistocene times. As indicated by extant populations in the Aegean Sea, Amphistegina is less temperature-dependent than other rotaliine larger foraminifers; this may help explaining the apparent paradox of its occurrence after the onset of Late Pliocene climatic deterioration.