Marine and continental clay deposits, dating from Early Pliocene to Late Pleistocene, widely crop out in the Umbria territory (central Italy). They belong to several lithostratigraphic units, the identification of which is in some cases still debated. The available allow to define almost homogenous outcrop areas, both in marine and continental deposits (Ambrosetti et al., 1977, 1987, 1995a, 1995b; Conti & Girotti, 1978; Basilici, 1992, 1997, 2000; Coltorti & Pieruccini, 1997; Girotti & Mancini, 2003). Four main clay units are usually defined: the Fabro Unit and the Chiani-Tevere Unit, which accommodate the Pliocene and Pleistocene marine sedimentary cycles, respectively, and the F.so Bianco Unit and Fighille Unit, which hold the wider outcropping continental clay in south and north Tiber Valley. In fact, clay deposits have been often used in cartography, as well in the geological models, independently on their meaning in terms of sedimentological, biostratigraphic, mineralogical features, and of paleoenvironmental context. New sedimentological and stratigraphic data are now available, and the former scenery needs a deep revision (Bizzarri, 2006; Baldanza et al., in press), at least for marine deposits. On the other hand, geotechnical and mineralogical features vary both with the age and the paleoenvironmental context (Candio et al., 1992). The results of an undergoing research project, based upon a multidisciplinary approach and aimed to a whole re-evaluation of Umbria clay sediments are here presented. Several sections have been sampled, both in marine and continental clay deposits, and sedimentological, stratigraphical, geotechnical and mineralogical analyses have been carried out, aimed to a comprehensive characterization of clay Units. Analyses are focused on grain-size, Atterberg’s limits, micropaleontology, x-ray diffrattrometry. The results of this multidisciplinary analysis will be useful in cartography, geotechnical studies, industry of ceramic and lateritious, archeometry and territory planning. Finally, this multidisciplinary approach, based upon a stratigraphic redefinition, contributes to the paleoenvironmental restoration and geological modelling.
Multidisciplinary analysis of the Plio-Pleistocene clay deposits in Umbria (central Italy): preliminary report
BALDANZA, Angela;CAMBI, Costanza;VINTI, Giuseppe
2011
Abstract
Marine and continental clay deposits, dating from Early Pliocene to Late Pleistocene, widely crop out in the Umbria territory (central Italy). They belong to several lithostratigraphic units, the identification of which is in some cases still debated. The available allow to define almost homogenous outcrop areas, both in marine and continental deposits (Ambrosetti et al., 1977, 1987, 1995a, 1995b; Conti & Girotti, 1978; Basilici, 1992, 1997, 2000; Coltorti & Pieruccini, 1997; Girotti & Mancini, 2003). Four main clay units are usually defined: the Fabro Unit and the Chiani-Tevere Unit, which accommodate the Pliocene and Pleistocene marine sedimentary cycles, respectively, and the F.so Bianco Unit and Fighille Unit, which hold the wider outcropping continental clay in south and north Tiber Valley. In fact, clay deposits have been often used in cartography, as well in the geological models, independently on their meaning in terms of sedimentological, biostratigraphic, mineralogical features, and of paleoenvironmental context. New sedimentological and stratigraphic data are now available, and the former scenery needs a deep revision (Bizzarri, 2006; Baldanza et al., in press), at least for marine deposits. On the other hand, geotechnical and mineralogical features vary both with the age and the paleoenvironmental context (Candio et al., 1992). The results of an undergoing research project, based upon a multidisciplinary approach and aimed to a whole re-evaluation of Umbria clay sediments are here presented. Several sections have been sampled, both in marine and continental clay deposits, and sedimentological, stratigraphical, geotechnical and mineralogical analyses have been carried out, aimed to a comprehensive characterization of clay Units. Analyses are focused on grain-size, Atterberg’s limits, micropaleontology, x-ray diffrattrometry. The results of this multidisciplinary analysis will be useful in cartography, geotechnical studies, industry of ceramic and lateritious, archeometry and territory planning. Finally, this multidisciplinary approach, based upon a stratigraphic redefinition, contributes to the paleoenvironmental restoration and geological modelling.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
