GNGTS 2019 - Atti del 38° Convegno Nazionale

152 GNGTS 2019 S essione 1.2 coincidence of the analysed deformation processes and the consistency of their deformation- rate are necessary constraints to validate an active geodynamic model. These two aspects are particularly tricky in regions showing the signature of superimposed deformation stages, where the most evident imprinting generally refers to past long-lived tectonic features rather than to active lineaments. In this case, the use of the morphometric analyses can represent an essential tool to support the parameterization of the active tectonic features, in terms of deformation- rate, cumulative displacements and kinematic evolution to be compared with the seismological and geodetic data. Landscape’s forms arise from the interactions between the relief-building endogenous forces and the smoothing actions of the surficial ones (Willet et al. , 2006). These latter have a transient nature which is ruled by their reaction and relaxation times. The duration of the relief dismantling depends on several combined factors, varying in time and in space accordingly to the age and the cumulative amount of triggering tectonic uplift, local lithological features and climate. The morphometric exploration of a region can express numerically the morphodynamic transience due to the deformation history occurred within the peculiar local relaxation time of the surface processes. The regional scale morphometric features thus refer to the effects of the long-term relief-building, potentially encompassing several superimposed deformation stages. Nevertheless, some morphometric indexes are particularly sensitive to the rejuvenation processes, providing useful tools in detecting the location and the entity of the deformation processes active at regional scale. This contribution provides an example of morphostructural and morphometric analyses of northeastern Sicily, at the southern termination of the Calabrian arc, where the occurrence of primary lithospheric faults, which accommodate the differential moving rates within the subducting Nubia Plate, between the Sicilian Collision Zone and the Ionian Subduction Zone. In this frame a still open issue regards the prolongation of these lithospheric faults through the Calabrian Arc within the overriding Eurasia Plate (Argnani & Bonazzi 2005; Gallais et al. , 2013; Polonia et al. , 2012; 2016). Northeastern Sicily experienced several and complex stages of tectonic deformation, resulting in an extremely fractured crustal domain (Pavano et al. , 2018). Thus, the occurrence of different fault systems, commonly recognizable just on a geological basis, is not necessarily responsive to the Quaternary-to-active tectonic dynamics. Morphological and morphometric investigations added new constraints for locating the active faults in the larger and widely distributed sets of Neogene fault systems, mostly active in the past. Combination of morphological evidence and morphometrics clearly identify the fresh landforms and morphostructures (e.g. marine and fluvial terracing, drainage system entrenchment and fluvial networks rearrangement, hanging paleo-landscape, offset morphological markers, fresh bedrock scarps, poorly-weathered striated fault planes) interacting with the active lineaments. Furthermore, morphometry provided information about the fault length, its actual offset, the age of the activity to be commensurate to the related historical and instrumental seismicity, the geodetic short-term deformations and the displacement-rate along the primary lithospheric scale faults. Our results highlight that in order to define a reliable tectonic deformation model, structural, seismic and geodetic data should be tightly combined with the numerical characterization of landscape’s morphology, including the analysis of active relief and drainage systems processes. This implies that the attempt to reconstruct the dynamic framework of Central Mediterranean need a multi-disciplinary approach and a careful debate within the entire Earth Science community. References A. Argnani & C. Bonazzi; 2005: Malta escarpment fault zone offshore eastern Sicily: Plio-Quaternary tectonic evolution based on new multichannel seismic data . Tectonics, 24 TC4009. Gallais F., Graindorge, D. Gutscher M.A., Klaeschen D.; 2013: Propagation of a lithospheric tear fault (STEP) through the western boundary of the Calabrian accretionary wedge offshore eastern Sicily (Southern Italy) . Tectonophysics 602, 141–152. http://dx.doi.org/10.1016/j.tecto.2012.12.026.