The geological, geomorphological and sedimentological features of the north-western Sicily continental shelf are hereillustrated with the aim to propose a geological model able to explain the Neogene-Quaternary evolution of the Sicilian continental marginin the context of the central Mediterranean region.Above the continental shelf and upper slope the sedimentary succession, showing along the different sectors of the margin considerablyvariable internal geometry and stratigraphic relationships with the underlying units, is interpreted as a IV order depositional sequence(Late Quaternary Depositional Sequence, LQDS) deposited during the last eustatic change (last 125 ky). The lower boundary of theLQDS is represented by a subaerial erosional surface formed during the last eustatic sea level fall ended in the LGM (20-18 ka). Thisunconformity lies above a seaward dipping Pleistocene succession whose depositional architecture is in turn controlled by Quaternaryeustatic sea-level fluctuations.A dense dataset of morphobathymetric and high resolution seismic data allowed to recognize along the continental shelf to bathyal plainsystem different types of continental shelf with different stratigraphic and morphostructural settings, associated to both large-scale processesand specific factors related to more local control: a) predominantly rocky shelves, both accompanied by a moderate frontal sedimentaryprism and with a structural edge, in the structural highs of the Monti di Palermo offshore and around the main rocky headlands(Capo San Vito, Monte Catalfano); b), depositional shelves, in the Castellammare, Palermo and Termini Imerese gulfs, both with aregular seaward deepening of the substrate and with a substrate uplift at the shelf break.We confirm that depositional sequences in this margin are the result of the interaction between sea level changes and sedimentation,but demonstrate that the tectonic activity has played a key role, not only in the creation of different types of continental shelves, but alsoto determine the different characters of each sequence in different areas.The general tectonic uplift during the Pleistocene, together with the episodic alternation of extensional and compressional events, oftenwith strike-slip component, is responsible for the thickness and facies variation both onland, where residual Pleistocene marine depositstoday outcrops, and in the continental shelf, where most of the depositional sequences developed and are now recognized. As welltectonic activity exerted a control on the geomorphological features (e.g. pockmarks and mounds) of the present day coastal areas andshelf-slope system, as well as for the submarine canyons and the mass failure processes.
|Numero di pagine||16|
|Rivista||Alpine and Mediterranean Quaternary|
|Stato di pubblicazione||Published - 2012|
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