Plio-Pleistocene deltaic deposits in the Città della Pieve Area (Western Umbria, Central Italy): facies analysis and inferred relations with the South Chiana Valley fluvial deposits.

The Plio-Pleistocene coastal marine deposits in the Città della Pieve area (western Umbria, central Italy) can be considered as a borderline among the Paglia Valley marine basin southward, and the South Chiana Valley and Tavernelle-Pietrafitta continental basins, north- and eastward respectively. Deposits, particularly on the Città della Pieve hill, have been traditionally referred to a deltaic environment and put in relation with river systems (Paleo-Tiber, Paleo-Nestore) draining the Tavernelle-Pietrafitta Basin. Moreover, previous authors considered the Città della Pieve lithostratigraphic succession as a reference scheme to reconstruct the evolution of western Umbria marine environments during Pliocene and Pleistocene. New data allow a revaluation of the Città della Pieve stratigraphic succession, whereas sedimentological and stratigraphic analyses lead to both a detailed description and a deltaic depositional context attribution. At the same time, studies on coeval South Chiana Valley continental deposits suggest a depositional continuity with coastal marine deposits and, in spite of previous authors’ interpretations, a main northern (Chiana Valley) alimentation for the Città della Pieve deltaic system.