GNGTS 2013 - Atti del 32° Convegno Nazionale

Along the south-western margin of the PMB this divergence in uplift is accommodated by a 10 km wide normal fault zone, represented by several NW-SE oriented, SW dipping fault segments that show clear evidences of Holocene activity, such as 2-5 m high fresh bedrock scarps (Pavano et al. , 2012), that recently was home of a low magnitude (M = 4.1, INGV) seismic swarm (June-September 2011). The tectonic deformation inferred a NE-ward tilting of several faulted blocks, imprinting the main features of the landscape, such as the drainage system. The morphometric analysis reveals evidences of huge fluvial captures, picturing a rearrangement of the fluvial network as a consequence of the tectonic tilting. The inherited main sub-sequent rivers, identified as the IV-VII order streams and flowing to the NW, maintained their orientation pushing to the NE the earlier symmetry of their basins. As regarding the I-III order streams, they should be considered as two main groups, distinguished on the basis of the flow direction data. The first group regards the streams pointing to the northern sectors, that, in addition to including streams inherited from the heads of previous basins, have complied the NE-ward tectonic tilting. This resulted in an increase in terms of length and basin extension. The second group is represented by steeper and shorter streams, flowing towards the SW as ob-sequent side streams, developing, as also evidenced by the NE-SW oriented swath profile, in correspondence of cumulative SW-dipping fault slope. The rightward basins asymmetry, the N-pointed fluvial captures, the NE-ward tilting of the summit surfaces and the general rearrangement of the fluvial network through the faulted block represent the morphological response of Late Quaternary tectonic activity occurred along the NW-SE oriented, SW-dipping normal faults, that bound the south-western margin of the PMB . These evidences enable to conclude that the active tectonic processes affecting the NE-Sicily since the Middle Pleistocene, strongly influenced the landscape evolution of the region, and in particular the drainage system. References A vena G.C., Giuliano G. and Lupia Palmieri E.; 1967: Sulla valutazione quantitative della gerarchizzazione ed evoluzione dei reticoli fluviali. In: Boll. Soc. Geol. It., 86. Benedetti L., Finkel R., Papanastassiou D., King G., Armijo R., Ryerson F.J., Farber D. and Flerit F.; 2002: Post-glacial slip history of the Sparta fault /Greece) determined by 36Cl cosmogenic dating: evidence for non-periodic earthquakes. In: Geophys. Res. Lett., 27. Boccaletti M., Nicolich R. and Tortorici L.; 1990: New data and hypothesis on the development of the Tyrrhenian basin. In: Paleogeog. Paleoclimat. Paleoecol., 77, 15-40. Catalano S. and Cinque A.; 1995: L’evoluzione neotettonica dei Peloritani settentrionali (Sicilia nord-orientale): il contributo di una analisi geomorfologica preliminare. In: Studi Geologici Camerti, Vol. Spec. 1995/2, 113-123. Catalano S. and De Guidi G.; 2003: Late Quaternary uplift of northeastern Sicily: relation with the active normal faulting deformation . In: Journal of Geodynamic, 36, 445-467. Catalano S., De Guidi G., Monaco C., Tortorici G. and Tortorici L.; 2008: Active faulting and seismicity along the Siculo- Calabrian rift zone . In: Tectonophysics, 453, 177-192. Catalano S. and Di Stefano A.; 1997: Sollevamento e tettogenesi Pleistocenica lungo il margine tirrenico dei Monti Peloritani: integrazione dei dati geomorfologici, strutturali e biostratigrafici. In: Il Quaternario, 10, 337-342. Cox R.T.; 1994: Analysis of drainage basin symmetry as a rapid technique to identify areas of possible Quaternary tilt-block tectonics: an example from the Mississippi Embayment. In: Geological Society of America Bulletin, 106: 571-581. D’agostino N. and Selvaggi G.; 2004: Crustal motion along the Eurasia-Nubia plate boundary in the Calabrian arc and Sicily and active extension in the Messina Straits from GPS measurements . In: J. Geophys. Res., 109, B11402. Finetti I.R. and Del Ben A.; 1996: Crustal Tectono-Stratigraphic setting of the Pelagian Foreland from new CROP seismic data. In: Finetti, I.R. (eds). CROP PROJECT: deep seismic exploration of the central Mediterranean and Italy. Chapter 26, 581-595. Hare P.W. and Gardener T.W.; 1985: Geomorphic indicators of vertical neotectonism along converging plate margin, Nicoya Peninsula, Costa Rica . In: Tectonic Geomorphology: Proceedings of the 15th Annual Binghamton Geomorphology Symposium, September 1984. Allen & Unwin: Boston. Hollestein Ch., Kahle H.-G., Geiger A., Jenny S., Geos S. and Giardini D.; 2003: New gps constraints on the Africa-Europe plate boundary zone in southern Italy . In: Geophysical Research Letters, 30, NO.18, 1935. ISIDEe Working Group (Ingv, 2010) – Italian seismological Instrumental and parametric database: http://iside.rm.ingv.it. 181 GNGTS 2013 S essione 1.2