GNGTS 2014 - Atti del 33° Convegno Nazionale

GNGTS 2014 S essione 3.1 13 lobes, channel/lobe transition features and scours (major erosional non-channel features). The derived characteristics, such as the fan divisions and sedimentation models are considered as secondary points only used as necessary for the discussion. The use of morphologic terms to describe ancient deposits has been also qualified. The primary emphasis remains on detailed, complete field work both on land and at sea in order to provide the characterization of the sediments and rocks assemblages and to ensure that similar features are being compared in terms of both temporal and physical scales (Mutti and Normark, 1987). Turbidite systems and their relationships to depositional sequences have been described in detail (Mutti, 1985). Long term global sea level variations and local tectonic control form the basic framework within which turbidite sediments develop as a response to breaks in the equilibrium between shelf and basin sedimentation. An understanding of the interaction of these processes and resulting types of turbidite deposition requires a precise framework of turbidite sediments within well defined depositional sequences. The volume of the gravity flows enhances the depositional characters of the channels that progressively become the only site of sand deposition where small volume and highly confined flows lose most of their fines through overbank processes. Within the same system, a decrease in the volume of gravity flows determines different stages of growth, that are expressed by distinctive facies associations. Channel-levee complexes, terminal deep sea fans and sediment wave fields associated with the Toyama Deep Sea Channel System in the Japan Sea have been described in detail (Nakajima et al. , 1998). The Toyama Deep Sea Channel in the Japan Sea is one of the most prominent deep sea channels in rifted margins. The course and morphology of the channel-fan system are mainly controlled by the basin morphology. Thick, sheet-like sediments, deposited from ponded turbidity currents have accumulated in narrow throughs, whereas extensive levees have formed in more open basins. The distribution of the sediments and the consequent morphology of the channel-levee complexes are also controlled by Coriolis force. The preferential development of the levees is attributed to the Coriolis force tilt effects in the Northern Emisphere. The distribution, form and orientation of the sediment waves are consistent with the effect and direction of inferred spill-over turbidity currents, with a consequent levee growth. The sediment transport may have ceased during the Holocene in the cut and fill tributaries developed in the Quaternary succession on the slope to the through, where a wide shelf separates the canyons from the rivers in the eastern margin of the drainage area. Important results on the stratigraphic architecture of deep sea depositional systems have been obtained from the GNV Italian project (Chiocci et al. , 2003). Further constraints have been obtained from the CARG Project (Aiello et al. , 2010, 2012) and from the Stromboli geophysical experiment (Castellano et al. , 2008; Aiello et al. , 2014). The submarine portions of the Italian volcanoes, their survey and the assessment of the potential volcanic hazards have been deeply investigated with a particular reference to the DTM generation for the Vulcano, Stromboli and the southern Ischia islands (Chiocci et al. , 2003). Other tasks have included the geotechnical characterization of submarine instabilities and related subaerial phenomena, the geotechnical analysis and modeling of instability phenomena affecting the flanks of the volcanic islands. Some researches on the Ischia submerged flanks have also been carried out, coupled with the reconstruction of the evolutive processes by marine data and with the seismo-stratigraphic analysis. Other objectives have included the understanding of the geological processes active in the Italian submarine areas, the evaluation of the potential risks associated with the volcanic seamounts and with the submerged portions of the volcanic islands of the Tyrrhenian sea. Investigations on the submerged portion of the Mount Etna volcanic edifice have also been carried out in order to ascertain the presence of tectonic lineaments, both extensional and compressional, connected with those on land, due to the absence of buttress towards the sea (Chiocci et al. , 2003). High-resolution seismic reflection profiles (Sparker Multitip) offshore southern Ischia island (Naples Bay) have been presented (Aiello et al. , 2012). New seismo-stratigraphic evidence on