Villafranchian deposits of the Barga and Castelnuovo Garfagnana basins (Tuscany, Italy): Lithostratigraphy and sedimentary features

Based on a refined mapping of the sedimentary wedges accumulated in the so-called Barga and Castelnuovo Garfagnana basins and on a review of previous studies, the distinguished formations are here described. The “Argille, sabbie e conglomerati di Fornaci di Barga” mainly consists of fine grained lithofacies with organic-rich horizons and coarse grained conglomerate. The “Conglomerati di Barga”, dominated by coarse grained lithofacies, is also characterized by silty to sandy interbeds, whilst organic-rich levels and paleosol horizons are rare. Within this formation, the Mt. Alfonso member is also distinguished, albeit hardly mappable. Sedimented in two separated tectonic depressions, connected by the “Mt. Perpoli high”, this succession has been interpreted in previous studies as ranging from cohesive sediment anabranching (“Argille, sabbie e conglomerati di Fornaci di Barga”) to gravel bed-load braided river deposits (“Conglomerati di Barga”), roughly flowing from north to south. In the Castelnuovo Garfagnana area, the Mt. Alfonso member also records the development of a tributary river flowing from west to east and interpreted as a braided fluvial fan. In this frame, the “Mt. Perpoli high” acted as a sedimentary by-pass, since the beginning of the sedimentation