“…The MRU is internally subdivided by c. N-S trending thrusts into the Iano-, the Monte Quoio-Montagnola Senese-and the Monte Leoni-Farma subunits (form structurally higher to lower and from internal to external; Figure 1, Costantini et al, 1988;Lazzarotto et al, 2003). The Monte Quoio-Montagnola Senese subunit is well exposed along the Farma River, where it appears to be composed of three metasedimentary formations, which, from oldest to the youngest, are: (a) the Risanguigno Formation (Lower Devonian based on Lazzarotto et al, 2003 and references therein; Middle Mississippian according to Capezzuoli et al, 2021), consisting of marine deposits comprising black phyllite intercalated with dolostone beds, radiolarian chert, green metasandstone, and quartzitic phyllite; (b) the Arenarie di Poggio al Carpino Formation (Late Permian-Early Triassic), the target of this study, which is composed of quartz-rich metasandstone, metaconglomerate, and minor metapelite deposited in shallow marine, inner shelf environments and shore deposits; (c) the Civitella Formation comprising green-gray metasandstone intercalated with lenses of metaconglomerate deposited in a alluvial fan system and belonging to the Verrucano Group (Lower-Middle Triassic; details and references in Aldinucci et al, 2008;Casini et al, 2008;Conti et al, 1991;Lazzarotto et al, 2003).…”