The Early-Middle Miocene marly-siliceous and siliciclastic sedimentation of the Tuscan Domain along the Mugello-Casentino-Arezzo alignment (Northern Apennines, Italy)

Piero Bruni ¹, Enrico Pandeli ^1,5, Mauro Papini ¹, Marisa Nocchi ⁴, Angela Baldanza ⁶, Giuseppe Aruta ¹, Lucina Luchetti ², Carlo Nini ³, Francesco Miniati ^1,5 & Elia Pasqua ^1
1Department of Earth Sciences, University of Florence - Via G. La Pira, 4 - 50121 Florence (Italy)., ²Environmental Protection Agency (ARTA) - Via Spezioli, 52 - 66100 Chieti (Italy)., ³ENI S.p.A. - Div. Exploration and Production, Via Unione Europea 3 - 20097 S. Donato Milanese-Milan (Italy)., ⁴Retired Professor of the past Department of Earth Sciences, University of Perugia - Piazza dell’ Università - 06123 Perugia (Italy)., ⁵CNR (National Research Council of Italy) - Institute of Geosciences and Earth Resources, Section of Florence - Via G. La Pira, 4 - 50121 Florence (Italy)., ⁶Department of Physics and Geology, University of Perugia - Via Pascoli snc, 06123 Perugia (Italy).

The Lower to Middle Miocene Vicchio marls s.l., at the top of of the Cervarola-Falterona tectonic unit, represents one of the best known foredeep to upper slope/external platform succession in the Northern Apennines tectonic pile. These very thick successions (locally more than 300 m-thick) are characterised by presence of black siliceous and volcanoclastic levels within silty marls in the lower part (“Fosso delle Valli member” at the top of the “Mt. Falterona sandstones”), and by calcareous-marly sediments with glauconite horizons, limestones with Lucina sp., slumps and calcarenitic/hybrid arenitic sediments in the upper part (“Vicchio marls”), respectively. Various sections, belonging to four typical areas and aligned along the Apennine ridge, were examined and correlated: Mugello (Rufina-Dicomano-S.Cresci and Vicchio sections), Casentino (Moggiona), Val Tiberina (Montefatucchio sections) and Arezzo (Subbiano-Montegiovi section). According to the field surveys, planktonic foraminifera and calcareous nannoplankton biostratigraphic data, the stratigraphic age of the Fosso delle Valli member can be attributed to the latest Aquitanian-middle Burdigalian time, while the overlying Vicchio marls s.s. to middle Burdigalian-Serravallian. Moreover, some stratigraphic gaps (i.e, paraconformities), locally marked also by significant bathymetric variations within the bathyal environment, were identified in the examined marly successions. The new data improve the lithostratigraphic-sedimentological and biostratigraphic-palaeoecological knowledge of the “Vicchio marls s.l.” and refine the architecture and the evolution of the outermost part of the Tuscan Domain during the latest stages of the Miocene syn-tectonic sedimentation.