Pliocene Lacustrine Deposits of the Tiberino Basin (Umbria, Central Italy)

• Autores: Giorgio Basilici
• Localización: Lake basins through space and time / coord. por Elizabeth H. Gierlowski-Kordesch, K. Kelts, 2000, ISBN 0891810528, págs. 505-513
• Idioma: inglés
• Texto completo no disponible (Saber más ...)
• Resumen

  • Pliocene lacustrine deposits are found in the Tiberino Basin, a depositional basin located in Umbria(central Italy) about 100 km north of Rome. The basin extends for 125 km in the north-northwest direction, with a width of up to 20 km (Figure 1). The Tiberino Basin is an extensional basin situated at the westernmargins of the Apennines Chain. Its origin is olderthan the middle Pliocene (sensu Rio et al., 1994) and itis connected with the tectonic extensive regime that brought about the opening of the Tyrrhenian Sea(Lavecchia, 1988). It is an asymmetric basin delimite don the eastern margin by a master normal fault (Martanafault) and by anthitetic normal faults on the western margins (Figure 2A). About 450 m of sedimentsare exposed in the study area, but a gravimetric survey(Ambrosetti et al., 1993) identified the depocenter tothe east of the basin axis with maximum sediment thickness of 2300 m near the village of Collevalenza(Figure 2B).The Tiberino Basin fill consists principally of siliciclasticdeposits. There are four lithostratigraphic formationsrecognized in the area between Marscianoand Terni (Figure 3): the Fosso Bianco Formation(FBF), the Ponte Naja Formation (PNF), the Santa Maria di Ciciliano Formation (SMCF), and the AcquaspartaFormation (AF) (Basilici, 1992).The Fosso Bianco and the Ponte Naja Formationswere deposited in an extensive lacustrine system; theirexposed thicknesses are 250 m and 140 m, respectively. The description of these formations is the object of this contribution. Pollen grains, as well as mammaland malacofauna remains, date these sediments as middle-late Pliocene (Follieri, 1977; Esu and Girotti,1991; Basilici et al., 1995;