Significance of the Pleistocene continental deposits cropping out in the Baronia Mts. in the framework of the quaternary evolution of northern Irpinia (southern Apennines, Italy)

Abstract

The travertine and reddish gravelly-sandy-silty deposits, cropping out in the Baronia Mts. (Irpinia, Southern Apennines, Italy) and provisionally named Vallata Unit, have been studied. The study area is part of the Sannio-Irpinia sector of the Apennines; in this sector the morphology is affected by the cropping out of Late Miocene silico-clastic flysch (S. Bartolomeo Fm), Pliocene clastic deposits (Altavilla and Ariano Units) and of Meso-Caenozoic basin units (Lagonegro Units). The landscape is characterized by some remnants of an old mature suspended morphology (the «Paleosuperficie» Auct.), the age and genesis of which, have been variously interpreted. The Baronia ridge represents a NW-SE oriented morpho-structural unit, which is defined at the borders by wide normal faults. The morphology is characterized by both some morpho-structural elements (such as fault slopes) and several inherited morphological elements (such as top palaeo-surfaces with remnants of the palaeohydrographic network and glacis). The Vallata Unit deposits form sandygravel lenses up to 40 m thick and up to some square kilometers wide. They are located between the glacis and the top palaeo-surface. The deposits are discontinuously arranged onto the Early-Middle Pliocene alluvial conglomerates and nearshore sands; their age has been referred to the Upper Pliocene and to the Early-Middle Pleistocene. The deposits are variously oxidised and reddish in color due to the intense weathering and local pedogenesis processes. On the basis of their sedimentological and stratigraphic characteristcs a cryonival genesis environment referable to the Pleistocene glacial stages is presumed. If this hypothesis were to be confirmed, these deposits would fill the gap in the evidence of the Quaternary glaciations and cold stages in the Apennines. As a matter of fact, the known glacial evidence are present north of Matese Massif and south of the Alburni Massif but are lacking in the Sannio-Irpinia sector of the Apennines.