Sand provenance of Le Dune and Torre Guaceto beach (Southern Italy).

The sandy littoral sectors of the Apulia Region (Southern Italy) show a large textural and compositional variability of the beach sands characterizing the different sedimentary dynamics of the Ionian and Adriatic coastal areas. The study areas include two Apulian pocket beaches (Torre Guaceto and Le Dune beach) which are representative of the coastal dynamics of a large sector of the central/northern Mediterranean Sea involving southern Adriatic Sea and northern Ionian Sea. Torre Guaceto beach is a 1 km littoral stretch located on the Adriatic Sea. Beach sediments range between coarse and fine sands and they include siliciclastic minerals and carbonate granules. Le Dune beach is located along the Ionian Seaside and develops for about 800 m. Beach sediments range from very coarse to mediumfine sands and they are mainly made up of bioclast fragments. Both study areas are part of marine protected reserves which includes 15 different habitats of the typical Mediterranean submerged populations and the presence of Posidonia oceanica meadows. Sedimentological, compositional and ecological investigations allowed describing the textural and petrographic characteristics of the beach sands by interpreting their sand provenance. The physical/biological interactions led us to analyse the beach sedimetary dynamics which is fundamental for pocket beach conservation. The sand compositional study highlighted the presence of mixed hybrid sands (terrigenous and bioclastic) and a longshore significant composition variability at Torre Guaceto beach, whereas the carbonate component (bioclasts more than 90% and lithics) represents the main element of Le Dune beach

An image analysis procedure to study the growth patterns of present-day coralligenous assemblages

Bioconstructions or biogenic reefs are more or less cohesive sedimentary bodies. They can consist of a large number of species of organisms capable of directly forming a rigid structure through the production of calcium carbonate or the aggregation of hard parts of benthic organisms. In coralligenous habitats, the interaction between physical and biological processes determines the evolution of the system. This work aims to describe the growth models of these bioconstructions, using a multidisciplinary and multiscale approach

The northern fault of the on shore-off shore Monte Giove re lief in the southern Adriatic Sea, Italy: implications for tectonic reactivation in the Apulian Foreland

We provide improved constraints on the timing, geometry and kinematics of the fault that may control the northern sub-merged morpho-structural relief termed Monte Giove, offshore from the town of Polignano a Mare. We have integrated onshore and offshore data, and interpreted seismic profiles from the ViDEPI project pertaining to the offshore Adriatic Sea of the Murge area, and made field observations north of Polignano a Mare. The fault has been surveyed onshore and mainly offshore along a distance of ~25 km. Generally striking E–W, it dips at high angle to the NNE in the west and to the N in the east. Active since at least the Cretaceous, this was reactivated after the Early Pleistocene with dextral oblique-slip kinematics. It borders the Monte Giove submerged relief/structural high, and continues eastwards in the Adriatic Sea into the Northern Deformation Zone/"Murge basse” graben, that in turn affected the onshore Murge area. Fault reactivation may have been related to a strain field in the outer part of the gentle buckle fold that involved the continental lithosphere of the Apulian Foreland (i.e., the areas of the Murge onshore and the Adriatic Sea offshore) since the Middle Pleistocene, as roll-back of the subducting lithosphere halted. Besides its tectonic reactivation, this fault has important implications as regards local seismic hazard, as well as the morphology influencing the present-day bioherm

Sediment provenance of a carbonate bioclastic pocket beach - Le Dune (Ionian Sea, South Italy)

This study focuses on the analysis of a carbonate bioclastic pocket beach located along a coastal sector of the Apulia Ionian Sea, Le Dune beach, South Italy. The beach develops for about 800 m and it is exposed to the south-westerly and southerly seas. Coastal sediments range from very coarse to mediumefine sands and they are mainly composed of bioclasts (more than 90%) which include molluscs, foraminifers, echinoderms, algae branched, bryozoans, spicules of sponges and arthropods. The study area is one part of a marine protected reserve characterised by 15 different habitats of the typical Mediterranean submerged populations and the presence of Posidonia oceanica meadows. The aim of our research is to highlight the correlation between physical and biological processes influencing Le Dune beach dynamics and its sediment provenance by analysing the textural and compositional characteristics of beach sands, which is fundamental for pocket beach conservation. The beach sand analysis, deriving from textural, compositional and bioclast investigations, underlines that one of the main indicators of the beach dynamics is the bioclast component, which provides relevant information about sand provenance and sediment transport. The beach constitutes a semi-close system only nourished by the shells of organisms and by the erosion of headlands and dunes without important sediment interchange with adjacent littoral sectors

Sedimentary features influencing the occurrence and spatial variability of seismites (late Messinian, Gargano Promontory, southern Italy)

Seventeen layers characterized by soft-sediment deformation structures (SSDS) were identified within the "calcari di Fiumicello", an upper Messinian (Miocene) stratigraphic unit (30 m thick), cropping out in the northern sector of the Gargano Promontory (Apulia, southern Italy). Facies analysis was performed on the whole outcrop and detailed sedimentological investigations were carried out on the deformed beds, in order to interpret the deformation mechanism, the driving mechanism and the possible trigger agent. Deformed layers occur in some thin-bedded ooidal limestones, skeletal calcarenite, as well as in some pebble-size conglomerate, alternated with marls, deposited in a protected embayment or barrier-island-lagoon system, possibly characterized by high salinity, and tidal influx. SSDS can be classified as load- and slump/slide structures. The continuous exposures allow us to follow a single deformed layer along tens of meters, hence several types of lateral variations were observed that can be summarized as follows: (1) SSDS disappear within a few meters (with a decreasing pattern of their deformation or in an abrupt way); (2) deformed layers laterally change in thickness and morphology; and (3) a single deformed bed can laterally correspond to two deformed beds. Most of the soft sediment deformation features were identified as liquefaction and/or fluidization features related to seismic shocks (seismites). Seismites are often used as an indicator of seismic events, especially along small outcrops, trench excavation and core analysis. This study highlights the value of the sedimentological analysis for paleoseismic investigations, with the aim of improving criteria for identifying seismites in the sedimentary record, and their suitability as marker of seismic events

Sediment provenance of a carbonate bioclastic pocket beach - Le Dune (Ionian Sea, South Italy)

This study focuses on the analysis of a carbonate bioclastic pocket beach located along a coastal sector of the Apulia Ionian Sea, Le Dune beach, South Italy. The beach develops for about 800 m and it is exposed to the south-westerly and southerly seas. Coastal sediments range from very coarse to mediumefine sands and they are mainly composed of bioclasts (more than 90%) which include molluscs, foraminifers, echinoderms, algae branched, bryozoans, spicules of sponges and arthropods. The study area is one part of a marine protected reserve characterised by 15 different habitats of the typical Mediterranean submerged populations and the presence of Posidonia oceanica meadows. The aim of our research is to highlight the correlation between physical and biological processes influencing Le Dune beach dynamics and its sediment provenance by analysing the textural and compositional characteristics of beach sands, which is fundamental for pocket beach conservation. The beach sand analysis, deriving from textural, compositional and bioclast investigations, underlines that one of the main indicators of the beach dynamics is the bioclast component, which provides relevant information about sand provenance and sediment transport. The beach constitutes a semi-close system only nourished by the shells of organisms and by the erosion of headlands and dunes without important sediment interchange with adjacent littoral sectors

The northern fault of the onshore-offshore Monte Giove relief in the southern Adriatic Sea, Italy: implications for tectonic reactivation in the Apulian Foreland

We provide improved constraints on the timing, geometry and kinematics of the fault that may control the northern submerged morpho-structural relief termed Monte Giove, offshore from the town of Polignano a Mare. We have integrated onshore and offshore data, and interpreted seismic profiles from the ViDEPI project pertaining to the offshore Adriatic Sea of the Murge area, and made field observations north of Polignano a Mare. The fault has been surveyed onshore and mainly offshore along a distance of ~25 km. Generally striking E–W, it dips at high angle to the NNE in the west and to the N in the east. Active since at least the Cretaceous, this was reactivated after the Early Pleistocene with dextral oblique-slip kinematics. It borders the Monte Giove submerged relief/structural high, and continues eastwards in the Adriatic Sea into the Northern Deformation Zone/”Murge basse” graben, that in turn affected the onshore Murge area. Fault reactivation may have been related to a strain field in the outer part of the gentle buckle fold that involved the continental lithosphere of the Apulian Foreland (i.e., the areas of the Murge onshore and the Adriatic Sea offshore) since the Middle Pleistocene, as roll-back of the subducting lithosphere halted. Besides its tectonic reactivation, this fault has important implications as regards local seismic hazard, as well as the morphology influencing the present-day bioherm

Analysis of the <i>Sabellaria spinulosa</i> Bioconstruction Growth in a Laboratory

Sabellaria spinulosa (Leukhart, 1849) is a suspension feeding polychaeta that lives in tubes consisting of terrigenous particles captured by the worm itself. They form impressive reefs containing millions of worm tubes. In temperate marine areas, under optimal environmental conditions, these structures can become natural breakwaters and can play an active role in sandy beaches’ defense. In this work, we report procedures aimed to analyze the growth of S. spinulosa bioconstructions in laboratory. By collecting biological replicas from a wild reef, this study aimed to identify sedimentological characteristics of sands that induce faster tube growth. During the tank experiments, the grain size and mineralogy of the sand were modified. By employing thin sections and X-ray microtomography analyses, the structures observed and measured during and after the tests were analogous to those naturally formed. The fastest growth was recorded in the presence of bioclastic sands with a grain size between 125 and 350 μm. Defining the physical conditions that induce faster growth is fundamental for the defense of these vulnerable habitats but also the surrounding marine environment. This study also lays the foundations for coastal protection interventions in which bioconstructions grown in the tank could be directly implanted on submerged natural and artificial substrates that are already present in situ

Texture and composition of the Rosa Marina beach sands (Adriatic coast, southern Italy): a sedimentological/ecological approach

Beach sands from the Rosa Marina locality (Adriatic coast, southern Italy) were analysed mainly microscopically in order to trace the source areas of their lithoclastic and bioclastic components. The main cropping out sedimentary units were also studied with the objective to identify the potential source areas of lithoclasts. This allowed to establish how the various rock units contribute to the formation of beach sands. The analysis of the bioclastic components allows to estimate the actual role of organisms regarding the supply of this material to the beach. Identification of taxa that are present in the beach sands as shell fragments or other remains was carried out at the genus or family level. Ecologi- cal investigation of the same beach and the recognition of sub-environments (mainly distinguished on the basis of the nature of the substrate and of the water depth) was the key topic that allowed to establish the actual source areas of bioclasts in the Rosa Marina beach sands. The sedimentological analysis (including a physical study of the beach and the calculation of some statistical parameters concerning the grain-size curves) shows that the Rosa Marina beach is nowadays subject to erosion