Plio-Pleistocene sedimentary facies and their evolution in centre-south-eastern Sicily: a working hypothesis

Abstract

This paper examines the distribution and evo- lution of the Plio-Pleistocene sedimentary facies in centre- south-eastern Sicily, especially around Enna, Licata and Caltagirone. Sectors occur in this region (Caltanissetta- Enna-Centuripe, Pietraperzia-Barrafranca-Piazza Armerina- Butera, S. Michele di Ganzaria-Caltagirone-Niscemi, Licata- Gela) where, in relation to the late Zanclean-Piacenzian / Selinuntian period, the sedimentary succession has different lithostratigraphic characteristics. The area studied belongs to the Caltanissetta Basin, which is a paleogeographical-sedimentary unit. From the Late Mio- cene to the Quaternary period it consisted of a dynamic fore- deep basin between the Hyblean Foreland and the Apennine- Maghrebian Trust front. Between the Early Pliocene and Early Pleistocene periods this front advanced about 50 km southwards and south-eastwards. The Plio-Quaternary lithostratigraphic sequence is mainly represented by 11 units: Zanclean Trubi Fm, Pliocene Argille Brecciate Fm. (Pliocene Brecciated Clays-AB IV, V), Enna Marls of the late Zanclean-Piacenzian, Centuripe Sandstones and Capodarso Calcarenites of the late Zanclean-Piacenzian, Geracello Clayey Marls of the Piacenzian-Selinuntian, Pi- azza Armerina Sands of the Piacenzian-Selinuntian, Mt. S. Giorgio Marly Clays of the Selinuntian, Caltagirone-Niscemi Sands of the Selinuntian, Terraced sediments of the Middle- Late Pleistocene, Present day sediments. There are three clear unconformities in the sequence, ex- cluding the one at the base of the quaternary terraced de- posits. The first, of late Zanclean age, is located above the Trubi Fm., and developed immediately after the beginning of the Enna Marls sedimentation; it has a synsedimentary char- acter and developed in a marine environment without emer- gence. The second, of late Piacenzian age, lies at the base of the Geracello Clayey Marls, while the third (Selinuntian), is located at the base of the Mt. S. Giorgio Marly Clays. Mi- nor unconformities, probably of glacio-eustatic origin, are locally present.