Sergio G. Longhitano

Sedimentology and hydrodynamics of mixed(siliciclastic-bioclastic) shallow-marine deposits of Acerenza (Pliocene, Southern Apennines, Italy)

During the Pliocene, along the Apennines front of Southern Italy (Acerenza area), a sector of the wedge-top basin hosted shallow-marine siliciclastic-carbonate (-bioclastic) sedimentation. Sediments consist of mixed arenites and rudites forming an up to 30 m thick unit. Based on the recognition of textural features, sedimentary structures, and degree of segregation between siliciclastic and bioclastic particles, facies analysis revealed 10 facies grouped into 5 associations. They suggest the occurrence of either wave or current dominated environments, showing different degrees of heterolithic segregation between siliciclastic and bioclastic particles. The depositional system was characterised by a gentle sloping profile irregularly undulated by syndepositional gentle folds. Waves dominated the shallowest areas of the mixed system and the terrigenous fraction derived mainly from wave erosion of substrate (arenaceous) rocks. These areas were located at the top of anticlines at depths corresponding to that of an upper shoreface sector of a classic coastal profile. The bioclastic fraction derived from the fragmentation of an in situ heterozoan skeletal-carbonate factory. Almost constant waves activity prevented segregation of the siliciclastic and bioclastic fractions in the lower shoreface zones. In relatively deeper environment of the mixed system (offshore transition), persistent unidirectional currents dominated, with development of tide-influenced 2D and 3D dunes. Repeated oscillations of the water column in the sheltered coastal areas produced modulation of current velocity favouring segregation of the heterolithic fractions along the dune foresets. Finally, in the deepest sector of the system (offshore), pervasive bioturbation dominated causing unsegregation of the siliciclastic and bioclastic fractions.

Tsunami and storm deposits preserved within a ria-type rocky coastal setting (Siracusa, SE Sicily)

Sedimentological and palaeoecological observations, accompanied by archaeological determinations and absolute dating, have been carried out on a recent beach-barrier system succession located 20 km south of Siracusa, south-eastern Ionian coast of Sicily (Italy). Th ese deposits fi ll the back edge of a ria incised within Miocene limestones and are composed of three main stratal units characterized by distinct sedimentological features. Th e two lower units, formed by crossbedded sands and laminated clays, recorded the development of a small confi ned beachbarrier depositional system, infl uenced by frequent high-energy events. Th e upper unit, represented by chaotic coarser sediments, can be attributed to a destructive marine high-energy event. Th e physical properties of the composing stratal units and the morphological setting of the study area allowed us to reconstruct a suite of stormand tsunami-related marine depositional processes that might have occurred in recent times along this area of elevated seismicity. In particular, absolute dating and archaeological determinations allow correlating the upper unit to a tsunami wave triggered by the 1693 AD catastrophic earthquake. Th e same depositional mechanism can also account for some of the coarse levels occurring into the underlying stratal units.

Sedimentological and morpho-evolution maps of the ‘Bosco Pantano di Policoro’ coastal system (Gulf of Taranto, southern Italy)

This paper presents the results of a sedimentological study performed to characterize the ‘Bosco Pantano di Policoro e Costa Ionica Foce Sinni’ coastal system, in Basilicata (southern Italy), as part of the PROVIDUNE LIFE Project. The study was focused on the morpho-sedimentological characterization of both the emerged and submerged sectors of the beach system developed along a 3.5 km-long segment of the Ionian coast. A multitemporal comparison of historical aerial photos of the studied coastline concerning the last 100 years was executed. A geomorphological survey was carried out along 36 topographic profiles (each up to 200-m long); these were coupled with bathymetric profiles, reaching a depth of −13 m. Both topographic and bathymetric profiles were measured on three occasions (July, October, December 2010). Textural and compositional analyses of sediments were also performed. The results of this study were synthesized in a series of maps illustrating a schematic geological outline of the study area, a reconstruction of the Sinni river course and shoreline changes from 1908 to 2010 (1:2,400 scale), significant topographic (1:1,300 scale) and bathymetric (1:5,000 scale) profiles, three bathymetric charts (1:31,000 scale) and morpho-sedimentological features of both the coastal and nearshore sectors (1:15,000 scale). This study provides a geological background that is crucial for any intervention planning, as well as for any coastal zone management projects. The results should be also used in order to protect coastal habitats, which is the ultimate goal of the LIFE project.

Tectonics and sedimentation of the Lower and Middle Pleistocene mixed siliciclastic/bioclastic sedimentary successions of the Ionian Peloritani Mts (NE Sicily, Southern Italy): the onset of opening of the Messina Strait

Biostratigraphic analyses carried out on siliciclastic/bioclastic deposits discontinuously cropping out along the Ionian flank of NE Sicily, indicate that they form two sedimentary events of Early and Middle Pleistocene, respec tively. Vertical facies successions, showing transgressive trends, suggest that sedimentation occurred within semi-enclosed marine embayments, where sublittoral coastal wedges developed on steep ramp-type shelves. Sediments accumulated in shoreface to offshore transitions along steep bottom profiles. This depositional scenario was strongly conditioned by the tectonic activity of the rift zone linking Western Calabria and Eastern Sicily. The effects of glacio-eustatism were also recognized. According to our reconstruction, the study area was controlled by a transfer fault system which affected the coastal margin producing major episodes of uplift and subsidence. Block-faulting was responsible for significant cannibalization and recycling of older deposits during the Middle Pleistocene. Such a tectonic setting can be considered the precursor scenario for the formation of the Messina Strait between Calabria and Sicily. This narrow, linear basin influences the hydrodynamic setting of sublittoral deposits along the Ionian coast of Sicily, giving rise to strong flood/ebb tidal currents. The uppermost part of the Middle Pleistocene succession recognized in the study area is indeed dominated by tide-influenced associations of sedimentary structures which most likely record the first stage of the opening of this ‘seaway’ of the central Mediterranean Sea.

Deflection of the progradational axis and asymmetry in tidal seaway and strait deltas: insights from two outcrop case studies

Abstract Deltas represent the major sediment source for tectonically confined, tide-dominated seaways or straits. Modern examples show how along-shore tidal currents are able to modify the impinging delta shape, generating asymmetrical coastal plains, deflected delta fronts and elongate sandbanks. Seaway or strait deltas can become become tide-influenced or tide-dominated, assuming physical attributes that may depart from classical models. Ancient deltas in seaways and straits can also reveal unexpected facies stacking and stratigraphies, which can be misinterpreted or attributed to different depositional settings. Two ancient analogues of deltas that prograded into elongate basins dominated by amplified tidal currents are presented here. A common element in these deltas is the progressive-upwards change in the dominant process of sediment dispersion recorded in the delta facies. Early stages of progradation are dominated by river- and wave-influenced lithofacies, whereas late deltaic advancements occur with a dominance of tidal current circulation on the delta fronts and the consequent morphologies are deflected/elongated in the direction of tidal flow. This study provides the basis for a preliminary stratigraphic framework for the depositional style of these types of delta. The studied deposits also suggest analogies with the spatial distribution of many hydrocarbon reservoirs investigated along the margins of confined, narrow, linear basins, the interpretation of which is still debated.

The 20,000-years-long sedimentary record of the Lesina coastal system (southern Italy): From alluvial, to tidal, to wave process regime change

The present-day Lesina area (Adriatic coast of southern Italy) preserves in the subsurface the stratigraphic signature of a recent sedimentary process regime change, which was responsible for the conversion of a former alluvial plain into a back-barrier tidal flat and, finally, into the modern barrier island. Facies-based analyses of the first 55 m of the upper Pleistocene–Holocene stratigraphic record, integrated with biostratigraphic sampling, radiocarbon data, and aerial observations of some diagnostic relict morphologies, allowed us to reconstruct the history of the last 20,000 years of this area. The succession investigated is adjacent to a salt dome, which uplifted in recent times, forming the easternmost boundary of the present-day Lesina lagoon. Three main stratigraphic intervals were detected in the subsurface: the lowermost unit is made up of conglomerates, sandstones, and mudstones of terrestrial origin, belonging to a complex system of alluvial plain filling a pre-existing Last Glacial Maximum (LGM) topography. The second interval consists of sands and muds, with subordinate conglomerates of brackish and marine origin, and lies on the previous one through a wide ravinement. Its composing lithofacies exhibit a strong tidal signature preserved in tidal rhythmites belonging to a net of tidal channels, associated with marshes, mud flat, and lagoonal deposits. These sediments record the emplacement of a back-barrier tidal flat, which developed under the strong influence of a tidal influx enhanced by the late post-LGM transgression. The third uppermost interval resulted from the deposition of coastal-marine sands and gravels accumulated during the ensuing modern normal regression, under the dominance of a wave-dominated coastal dynamics, which was responsible for the progradation of the present-day beach barrier and the closure of the Lesina lagoon. The paleogeography of the back-barrier tidal flat preceding the onset of the modern barrier island is thus reconstructed based on the results of our facies analysis, biostratigraphy, and AMS dating. Many of the elements composing this mid-Holocene tide-influenced system were also interpreted from the aerial-photograph observation of several relict morphologies, which are still preserved in many parts of the modern Lesina barrier island. We propose some new interpretation on the origin some of these elements, which possibly developed under sedimentary process regimes different from the modern ones, including some flood-tidal deltas, previously interpreted as tsunami-derived washover fans.

Tidally influenced shoal water delta and estuary in the Middle Jurassic of the Søgne Basin, Norwegian North Sea: sedimentary response to rift initiation and salt tectonics

Abstract Recent studies in the Middle Jurassic Bryne and Sandnes formations, primary reservoirs in several fields across the Norwegian and Danish North Sea, show the widespread occurrence of tidal-influenced and tide-dominated deposits. Aalenian–Bajocian Bryne cores reflect deposition by a shoal water, tidally influenced delta onto a low wave energy tidal platform (both supratidal and intertidal) that probably occupied the majority of the Søgne Basin, a narrow rift system connected to the Central and Danish graben and transgressed from an open-marine basin, possibly located to the south. At the Bathonian–Callovian boundary, a new phase of rifting and progressive salt movements led to the deposition of the upper Bryne and Sandnes formations within an 80–100 km long composite estuarine valley. Basin tilting to the south and continued transgression resulted in tidal deltas that offlap the northern margin of the basin. The basin was fully transgressed by the end of the Callovian. From the Late Bathonian onwards, differential tectonic movements along the broadly interconnected Middle Jurassic rift basins led to a change in the transgression direction from south to north, with an open-marine basin located in the Central and Viking graben.

Studio sedimentologico e dinamica marino-costiera del sistema litorale di Bosco Pantano di Policoro (Basilicata, Italia meridionale)

Sedimentological study and coastal-marine dynamics of the Bosco Pantano di Policoro littoral system (Basilicata, Southern Italy).The PROVIDUNE LIFE project is a multi-disciplinary research task funded by the European Community and designed to outline the framework of the natural habitats of the dune fields that occur along the coasts of Cagliari (southern Sardinia), Caserta (northwestern Campania) and Policoro (eastern Basilicata) in southern Italy. The project consists of a number of interconnected studies programmed to evaluate all the environmental features that the coastal dune fields exhibit along these coasts of the central Mediterranean area. This paper shows the result of the sedimentological study performed to characterize the Bosco Pantano di Policoro e Costa Ionica Foce Sinni coastal system, in Basilicata (southern Italy). This system, developing along a 3 km-long segment of the Ionian coast, shows an up to 100 m-wide, mixed (gravelly-sandy) beach, which is wave-dominated and subjected to persistent NNW-directed waves. The study has been focused on the morpho-sedimentological characterization of both the emerged and the submerged sectors of the beach system. Accordingly, 36 topographic and bathymetric profiles have been measured, and analyses to obtain compositional and textural features of deposits were carried out. Furthermore, an evolutive model of the shoreline changes during the last 100 years has been depicted on the base of a multitemporal comparison of historical aerial photos. Finally, in order to achieve a series of prediction models on the impact of the dominant wave and the resulting hydrodynamics of the coastal area, the more frequent and of greater energy events have been identifi ed and, thanks to the Delft3D software, the effects they can have on coastal systems have been evaluated.This kind of study provides all the geological elements that must be taken into account for any planning of interventions as well as for their management; in any case, the result should be used for the purpose to protect coastal habitat, that is the ultimate goal of this LIFE project.

Geoturismo in Basilicata: il Parco Letterario Carlo Levi ad Aliano quale veicolo di divulgazione di elementi di geologia del sedimentario

Geotourism in Basilicata (Aliano, Southern Italy): the Carlo Levi Literary Park as a medium to initiate neophytes into sedimentary geology.The Aliano village hosted the political relegation of Carlo Levi during the fascist period. It is diffi cult to imagine the shock suffered by Carlo Levi when he reached in the 1930s this locality of the deep south of Italy coming from a big city as Turin. Contrarily to prejudices, Carlo Levi found a good feel with the rural people of Aliano, and he is still remembered from people, after 35 years since his death.The geological landscape crossed and described by Carlo Levi both with paintings and writings was (and is) signifi cant. Following the footprints of Carlo Levi and thanks to the istitution of a Leterary Park dedicated to him, it is possible today to appreciate the geology of the area and to suggest a geotouristic trip linked to the history of the political relegation of Carlo Levi.