• basin analysis
• detrital zircons
• Northern Apennines
• sediemtary petrology
• turbidites

This thesis was developed within the framework of the CARG project (Geological and Geotechnical Cartography of Italy), funded by the national public institution ISPRA to create a 1:50,000 scale geological map covering the entire Italian territory, totaling 636 geological sheets of equal dimensions. This work is part of the activities carried out by the Department of Earth Sciences of the University of Pisa in sheet number 288 of the province of Arezzo. In this area, the Falterona Formation constitutes 80% of the bedrock, thus requiring characterization through petrography and geochronology. This was accompanied by comparison with the Macigno Formation, also outcropping in the study area, to contribute to the complex issue of recognizing and classifying foredeep basins in the Northern Apennines, using techniques never applied to these deposits, such as the study of detrital zircons and petrographic characterization for the Falterona Formation. This work aims to characterize the turbiditic deposits of the Falterona and Macigno Formations, typical foredeep deposits sedimented in the Upper Oligocene - Lower Miocene (Ricci Lucchi, 1986). Despite the tectonic context in which these deposits formed being ideally defined, there is a lack of dedicated study describing the Falterona Formation, often merged with other similar formations, such as the Cervarola Formation. The study area is in the southern sector of the Northern Apennines, an orogenesis resulting from the closure of the Ligurian-Piedmontese oceanic basin between the European and Adria plates (Molli, 2008; Marroni et al., 2010). In the initial stages, during the Alpine phase, intra-oceanic subduction (Late Cretaceous - Middle Eocene) had a subducting plane towards the east, with the European plate in the lower plate position and the Adria plate as the upper plate. In the Middle-Upper Eocene, this subduction ceased due to the involvement of the thick continental crust of the European/Corsican plate in the subduction plane (Molli, 2008; Marroni et al., 2010). Despite the forced cessation of subduction, convergence continued, causing in the Oligocene a reversal of the subduction plane with westward dipping and the involvement of the Adria plate in underthrusting processes (Molli, 2008; Marroni et al., 2010). At this point, the Ligurian-Provençal back-arc basin began to open, leading to the separation of the Sardinian-Corsican block from the European plate and its rotation together with the Apennine system, beginning its migration eastward (Molli, 2008). During this phase, the Northern Apennine wedge developed a series of thrusts and folds, gradually stacking different tectonic units. The two formations studied, along with the Cervarola Formation, are part of the Tuscan Domain, representing the internal continental margin of the Adria plate, more precisely representing the top of the Tuscan Nappe. The Macigno, Falterona, and Cervarola Formations are thick turbiditic sequences formed in the foredeep of the Northern Apennines between the Oligocene and the Miocene, whose sedimentation was controlled by the Apennine tectonics (Ricci Lucchi, 1986; Conti et al., 2020). The available literature on the Falterona Formation is deficient; it is usually described together with other foredeep formations. Plesi et al. (2002) first hypothesize a difference between the Falterona and Cervarola Formations. Catanzariti et al. (2009) confirm through biostratigraphy that the Falterona Formation has more affinities with the Macigno Formation than with the Cervarola Formation, suggesting the existence of two coeval basins. This is further supported by the petrographic data of Cibin et al. (2004), which distinguish the Cervarola and Falterona formations based on a higher content of carbonate fragments and a lower content of metamorphic fragments in the Cervarola Formation compared to the Falterona Formation. The Falterona and Macigno Formations have the same age (Chattian) at the base and a different age at the top (Upper Aquitanian and Lower Aquitanian respectively), suggesting that these two formations began their sedimentation simultaneously until the Macigno basin was deactivated and incorporated into the Apennine prism (sheet 288 "Arezzo": Marroni et al., in press). The thesis work began with the sampling of the two members Monte Falco (FAL1) and Camaldoli (FAL2) of the Falterona Formation, near the locality of Subbiano, for a total of 19 samples (7 for the first member and 12 for the second), and the Poggio Belvedere member (MAC2) for the Macigno Formation in the locality of Civitella Val Di Chiana (9 samples). Thin sections were prepared by the Ts Lab. laboratory in Navacchio (Pi), while zircon separation for geochronological analyses was performed between the laboratories of the Department of Earth Sciences of the University of Pisa and the A. Desio Department in Milan. At the end of the sample preparation process, 25 thin sections were analyzed (5 for the Monte Falco Member, 12 for the Camaldoli Member, and 8 for the Macigno Formation member) for modal counting, petrographic characterization, and 188 zircons were dated using the U-Pb method (19 for the Monte Falco Member, 99 for the Camaldoli Member, and 70 for the Poggio Belvedere Member). The petrographic and geochronological results obtained in this thesis work confirm the hypothesis of Catanzariti et al. (2009). Cibin et al. (2004) further support this hypothesis by highlighting a petrographic difference between the Falterona and Cervarola Formations, indicated by a sharp increase in carbonate fragment content from the Camaldoli Member upwards. Although carbonate fragments remain a marginal component of the framework, this characteristic is visible both in the modal analysis conducted and in the field, with the reaction to HCl in the Camaldoli Member but not in the Monte Falco Member. The geochronological data confirm similarities between the Poggio Belvedere Member and the members of the Falterona Formation, from which the same age ranges were derived. The data obtained not only allowed characterization of the Falterona Formation through comparison with the Macigno Formation, but also provided important information on the source area of the turbidites that originated these deposits. Many studies in the literature indicate a provenance from the Western-Central Alps mainly based on paleocurrent data (Valloni and Zuffa, 1984; Cornamusini, 2002; Monaco et al., 2010; Amendola et al., 2016); whereas the data in this thesis confirm that these two basins were fed from the same source, mainly from the Southern-Central Alps, excluding or significantly diminishing the role of the Western Alps in filling these basins. However, further studies are necessary. A comparison with the Cervarola Formation using techniques like those used in this thesis work would be useful to verify any correlations. A cartographic review at the scale of the Northern Apennines is needed, where the Falterona and Cervarola Formations are reported, considering the stratigraphic characteristics and the tectonic interpretation related to the basins in question. It is also important to consider the geodynamic environment in which these basins developed; the rate of incorporation of the Apennine thrust is such that the closure of one basin is probably concomitant with the opening of the next one (Lucchi, 1986). Therefore, we should not expect unequivocal characteristics for these deposits but a gradual and almost imperceptible change at the microscopic level, where each deposit represents a transition from the previous to the next.