Regional scale morphotectonic pattern of the Tyrrhenian Sea

Digital Elevation Model (DEM) data analysis has been applied in several environmental and geological studies. At a regional scale, morphological analysis has been applied to detect tectonics affecting onland surfaces, based on the analysis of morphological lineaments (Burbank and Anderson, 2001). The interpretation of seafloor morphological lineaments and their relationship with tectonics is less advanced, due to the scarcity of high resolution data available at regional scale. This work shows the results of a combined use of DEM analysis on swath bathymetry and on tectonics in order to investigate from a morphotectonic viewpoint the seabottom features in the Tyrrhenian Sea. The morphology of the entire Tyrrhenian Sea has been analysed based on middle resolution multibeam bathymetry and on 100 m-contour lines (scale), part of a "Tyrrhenian project" (Marani et al., 2004). A first morpholineaments map has been created identifying more than 500 features > 10 km in length, without considering their tectonic settings and the timing of their development. Furthermore, a Tyrrhenian regional tectonics map has been digitized from literature. Maps 1:1.500.000 (Ambrosetti et al., 1987) and 1: 500.000 (Barone et al., 1983) were used to extract a faults network. Morpholineaments and tectonic lineaments have been grouped in six Tyrrhenian Sea geographical zones and plotted in rose diagrams in order to obtain the main trends in each region. Rose diagrams show that most of the identified morpholineaments have a tectonic origin, although they are not coeval, as they developed during different phases of the opening of the Tyrrhenian back-arc basin. Results suggest that the Northern, Western and Central Tyrrhenian are dominated by a main trend, controlled by extensional tectonics related to the progressive retreat of the slab subduction, in contrast, the occurrence of several trends in the Eastern and Southern Tyrrhenian suggests additional tectonic complexities in those regions.