IL SOVRASCORRIMENTO DELL'UNITA' TRASIMENO SULLA SUCCESSIONE UMBRA DELLA ZONA DI UMBERTIDE: DATI STRATIGRAFICI E STRUTTURALI

Abstract

A sector of the Umbrian thrust belt is examined here: the '' Argille vari colori line'' near Umbertide (Tevere Valley) in which the Trasimeno Unit thrusts over the Umbrian suc­cession. From a biostratigraphic point of view the uppermost part of the Umbrian succession (i.e. the Marnoso-arenacea for­mation) and the Trasimeno succession were analyzed. The Marnoso-arenacea formation belongs, on the basis of its planktonic foraminifera contents, to the N7 Bww biozone. The top of the formation corresponds to the uppermost part of the same biozone. The Argille varicolori formati on of the Tuscan succession belongs to the N3 Bww biozone and it is entirely comprised in the Oligocene. The Trasimeno Mio­gypsina sandstone basal levels were also re-examined. They result early-Aquitanian in age on the basis of the study of Miogypsina embryonic apparatus evolution degree. [...]