Francesca Budillon

Evidence for a variable paleomagnetic lock‐in depth in the Holocene sequence from the Salerno Gulf (Italy): Implications for “high‐resolution” paleomagnetic dating

We report on a paleomagnetic and rock magnetic study of two adjacent marine gravity cores from the Salerno Gulf (Italy), with measurements carried out on u-channel samples at 1-cm spacing. The cores recover a sedimentary sequence spanning, in the overlapping part, the last ∼6000 years and include a thick (∼1 m) pumice layer produced during the Somma-Vesuvius eruption of 79 A.D. Rock magnetic and lithostratigraphic data provide several tie-points for a detailed correlation between the two cores. Paleomagnetic data allow the determination of a well-defined characteristic remanent magnetization, with very similar stratigraphic trends and distinct features that can also be unambiguously correlated between the cores. However, the comparison of the various data sets points out that the paleomagnetic lock-in depth in the two adjacent cores varies through the stratigraphic succession. We discuss the implication of such results for assessing the potential of high-resolution paleomagnetic studies in dating sedimentary sequences on the basis of paleosecular variation of the geomagnetic field. In the studied case, the relative difference in the lock-in depth in the two cores causes “spreading” of the assigned paleomagnetic ages at a century scale.

Sandy beaches characterization and management of coastal erosion on western Sardinia island (Mediterranean Sea).

ABSTRACT De Falco, G., Budillon, F., Conforti A., De Muro, S., Di Martino G., Innangi, S., Perilli, A., Tonielli, R., Simeone, S. 2014. Sandy beaches characterization and management of coastal erosion on western Sardinia island (Mediterranean sea).In: Green, A.N. and Cooper, J.A.G. (eds.), Proceedings 13th International Coastal Symposium (Durban, South Africa),Journal of Coastal Research, Special Issue No. 70, pp. 395–400, ISSN 0749-0208. Coastal erosion is a global problem which affects sandy and rocky shores worldwide. Coastal erosion can be triggered by several causes. Local processes can generate erosion hot spots, whereas at the global scale, the main forces are sea level rise, changes in storm climate and human interference. Beaches along the Mediterranean sea are strongly affected by coastal erosion. Recently, the Protocol on Integrated Coastal Zone Management in the Mediterranean (PAP/RAC 2007) recommended the prevention of erosion processes by restoring the natural adaptive capacity of the coast and by improving the knowledge on the state, development and impact of coastal erosion. In order to achieve the objective of the PAP/RAC protocol, we characterized 24 sandy beaches along ~270 km of the western coastline of the Sardinia island (western Mediterranean). Grain size and mineralogy of the foreshore sediments were analyzed and the intertidal elevation/bathymetric profile were measured using the Differential Global Positioning System. Aerial photos were used to identify the shoreline configuration, the number of bars and morphodynamic features. A digital elevation model (DEM) of the adjacent shelf was produced and acoustic backscatter, grab and box-corer sediment samples were collected in order to characterize the seafloor and to identify the substrate lithology, particularly the distribution of sandy sediments. The investigated coastline is characterized by linear, multibarred beaches and wide transgressive dune fields formed by terrigenous and coarse sand. These linear beaches are alternated with embayed beaches which locally show a mixed terrigenous/bioclastic carbonate composition. Large sandy bodies were found in the inner shelf, often forming dune fields which were uncovered by mud drapes. A database was created to facilitate the characterization of the beach systems along the studied coastline and adjacent inner shelf. It is anticipated that the database will be used by policy makers in support of the implementation of coastal erosion management strategies.

Distribution of Posidonia oceanica (L.) Delile meadows around Lampedusa Island (Strait of Sicily, Italy)

ABSTRACT We present a seabed map around Lampedusa, the largest island of the Pelagie Islands Marine Protected Area (Italy, western Mediterranean). The seafloor was mapped using bathymetry and backscatter multibeam systems along with an underwater camera for direct observations and ground truthing, from the coastal area to about 50 m depth. The map was produced to monitor the present-day distribution of the Posidonia oceanica meadows around the Island. P. oceanica is the most important endemic seagrass species of the Mediterranean Sea and it can form meadows or beds extending from the surface to 40–45 m depth. These meadows provide habitat for a large marine community, thus increasing biodiversity of the coastal zone, stabilizing sediments and reducing coastline erosion. The seagrass meadows are susceptible to regression in response to specific impacts, thus their presence and abundance is an indicator of the overall environmental quality of the coastal zone. Recently, within the Marine Strategy Framework Directive (2008/56/EC), P. oceanica has been selected as an indicator of the Good Environmental Status for marine areas. Consequently, the Pelagie Islands Marine Protected Area launched a project to assess the conservation status and map the distribution of P. oceanica meadows. The resulting 1:15,000 scale map includes information about the Mediterranean seagrass and the distribution of five acoustic facies reflecting hard lithologies and soft substrates. The Lampedusa seabed map provides new information, which contributes to the development of a detailed benthic habitat map and a more comprehensive maritime spatial planning of this Marine Protected Area.

Recurrent Superficial Sediment Failure and Deep Gravitational Deformation in a Pleistocene Slope Marine Succession: The Poseidonia Slide (Salerno Bay, Tyrrhenian Sea)

A large number of exposed scars, originated by multievent sediment failures, have been identified on the southern flank of a deep submarine valley in Salerno Bay (Southern Tyrrhenian Sea), between depths of 300 and 700 m. A 200 km2 complex landslide lies across a 17 km-long SW-NE trending anticline, which is exposed 40 m above the seafloor of the continental slope and folds a Pleistocene marine successions. The exposed anticline, as well as others which are more subdued, have been formed by gravity-driven deformation of a deep and unconsolidated slope succession. The deep deformation seems to be coeval with recent stages of regional tectonic activity, given that a regional unconformity related to MIS 6 lowstand seals both the deep landslide features and the fault planes. A combined dataset of 2D high resolution seismics, swath-bathymetric digital elevation model of the seafloor and a gravity core was used to establish a possible relation between recurrent sediment failures at the seabed and the stack of positive reliefs in the compressional toe region of the buried landslide system and to learn more on the timing of the deformation phases.

Seabed mapping in the Pelagie Islands marine protected area (Sicily Channel, southern Mediterranean) using Remote Sensing Object Based Image Analysis (RSOBIA)

In this paper we present the seabed maps of the shallow-water areas of Lampedusa and Linosa, belonging to the Pelagie Islands Marine Protected Area. Two surveys were carried out (“Lampedusa 2015” and “Linosa 2016”) to collect bathymetric and acoustic backscatter data through the use of a Reson SeaBat 7125 high-resolution multibeam system. Ground-truth data, in the form of grab samples and diver video-observations, were also collected during both surveys. Sediment samples were analyzed for grain size, while video images were analyzed and described revealing the acoustic seabed and other bio-physical characteristics. A map of seabed classification, including sediment types and seagrass distribution, was produced using the tool Remote Sensing Object Based Image Analysis (RSOBIA) by integrating information derived from backscatter data and bathy-morphological features, validated by ground-truth data. This allows to create a first seabed maps (i.e. benthoscape classification), of Lampedusa and Linosa, at scale 1:20 000 and 1:32 000, respectively, that will be checked and implemented through further surveys. The results point out a very rich and largely variable marine ecosystem on the seabed surrounding the two islands, with the occurrence of priority habitats, and will be of support for a more comprehensive maritime spatial planning of the Marine Protected Area.

Sorted Bedforms Along the Continental Shelf of Western Sardinia

Two sorted bedforms fields located at the western Sardinian margin are described. Bedforms are developed at the edge of prograding sedimentary wedges related to the last sea-level rise and in a small basin of the inner shelf, surrounded by rocky outcrops. The mechanisms of formation and evolution are discussed in relation with sea-level oscillations, hydrodynamic forcing and complex seabed morphology.