Villafranchian deposits of the Barga and Castelnuovo Garfagnana basins: 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 sepa- rated tectonic depressions, connected by the “Mt. Perpoli high”, the 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.