Osservazioni geomorfologiche, stratigrafiche e pedologiche sul Quaternario del Bacino di Boiano (Campobasso)

Abstract

This study aims at defining the sequence of morphoevolutionary events which occurred in the Boiano area. In particular, the tectonic genesis of the Boiano basin is highlighted using morphologic and sedimentary features of the deposits surrounding the studied site. The basin is filled by fluvio-lacustrine sediments (the thickness of which is still uncertain). In some excavations in the area of Campochiaro, the infilling outcrops for a few tens of meters. It consists of a complex ailuvium-detrital sequence with inclusions of paleosols having different thickness and development, more specifically Vertisols and fluventic Entisols. Present-day soils consist of Andosols, which have been studied and used for correlations. The first important tectonic phase in the basin appears to date to the early Pleistocene during which a fluvio-lacustrine basin - the San Massimo basin - was formed. A second tectonic phase, probably occurring between the end of the early Pleistocene and the beginning of the middle Pleistocene, deformed sediments and pre-existing forms to produce a new fluvio-lacustrine basin - the Boiano basin -, embedded in the previous one. Sedimentation processes in this basin ended about in the late Pleistocene. Technically, outcropping sediments and forms attributable to this period are not deformed and can be regarded as "morphoclimatic relicts". This has been proved by a paleopedological study carried out on the "Campochiaro" sequence. At present, the Boiano basin shows an exoreic superficial runoff with clear evidence of erosion of the old fluvio-lacustrine deposits.