Acquisition of morpho-structural data by the use of aerial lidar and proximal sensing in the southern end of Monte Altissimo syncline (Apuan Alps, Italy)

A new interpretation of the tectonic evolution of the southern end of Monte Altissimo syncline is given in this study on the basis of new information acquired through traditional geo-structural survey and photo-interpretation of data derived from airborne lidar and optical proximal sensing. The high spatial resolution and the geometric accuracy of the data led to the creation of digital geo-referenced products and, through the creation of 3D models with decimeter accuracy, the digitization of new morpho-structural elements. The study area is known in the geology of Apuan Alps because is studied since late nineteenth century by several authors among which Zaccagna (1932), Giglia (1967), and Meccheri et al. (2007). The interest in this zone is also increased by the presence of precious marbles cultivated by the Henraux company since 1821. The Monte Altissimo syncline has an approximately North-South trend for about ten kilometres in the Apuan Alps tectonic window (Northern Apennines). In the area of interest, the syncline is characterized by a core consisting of the Marbles Formation (Hettangian). The syncline flanks consist of carbonate formations with aged between Noricum and Hettangian (Megalodont Marbles, Seravezza Breccias and Grezzoni dolomites), that overlay the Hercynian basement. The tectonic evolution of the Apuan metamorphic complex is polyphasic, characterized by ductile and fragile deformation, and connected with the tertiary evolution of the orogenic Apennine wedge. In the area the following elements are particularly evident: i) the deformation geometries in low metamorphic state (green schists facies), produced by the compressional tectonic regime, which led to the structuring of the Monte Altissimo large isoclinal syncline with an East vergency; ii) the effects of the retro-deformation, created during ductile regime and low grade metamorphism, probably contemporary to the final stages of the orogenic wedge building, which develops a kilometric synform/antiform structure with a West vergency; iii) a subsequent deformative phase characterized by significant shear zones and low angle normal faults connected to the left and right transfer systems which overlaps the previous fold systems. These systems of faults and shear zones represent a novelty in geological knowledge of the area that have been studied thanks to availability of a low altitude photogrammetric survey acquired through the multi-parametric vehicle developed by the Centre of Geotechnology of Siena University.