Ricostruzione paleoclimatica attraverso l'analisi di uno speleotema nella Sardegna centro-orientale: risultati preliminari

This paper, carried out in the framework of a local project 60% «Pleistocene-Holocene palaeoclimate and palaeogeography reconstructions based on marine and continental deposits of Sardinia» (Resp. Prof. Sandro De Muro) and within a series of researches involving several bodies (Archaeological Superintendence of NU/SS, Universities of Parma and Cagliari) and caving associations (Gruppo Speleo Ambientale Sassari, Gruppo Speleo-Archeologico Giovanni Spano of Cagliari, Unione Speleologica Cagliaritana and Gruppo Archeo Speleo Ambientale Urzulei), reports the first results of a palaeo-climate study carried out on a stalagmite sampled in the Su Palu cave, Codula Ilune, Urzulei (Central-East Sardinia). This stalagmite has been subjected to radiometric U/Th dating and stable isotope δ180 and δ 13C analysis. These isotopic data based on 139 samples showed a general increase in stable isotope ratios that would indicate a growth of the concretion in a period of global warming (Upper Pleistocene- Holocene?). The chronological setting by means of U/Th datings, unfortunately, did not allow to define the exact timeframe because of the presence of detrital Thorium. C14 analysis are under way to try to obtain information on the time during which the stalagmite growed

Glacigenic features and Tertiary stratigraphy of the Magellan Strait (Southern Chile)

The seismostratigraphic and structural analysis of the whole length of the Magellan Strait, from the Atlantic to the Pacific entrance is for first time illustrated on the basis of multichannel seismic (MCS) profiles. The Strait crosses a geologically complex region that includes different morphotectonic provinces, and has been subdivided into three distinct segments, eastern (Atlantic), central, and western (Pacific), being each segment characterized by peculiar sedimentary and tectonic architectures. The MCS profiles shed light on the subsurface of the region in particular on the Quaternary and Tertiary features. In the foreland basin province, the MCS profiles imaged an almost undeformed structural and stratigraphic frame with very thick Cretaceous to Tertiary package. Seismic evidence of deformation of the foreland units occurs in the fold-and-thrust belt province. Along the Cordillera province, the Magallanes-Fagnano transform fault exerts an important morpho-tectonic control that strongly conditions its bathymetric profile. The seismic profiles also highlighted a number of depositional features linked to the up to 150 m thick sedimentary record of the glacial cycles. Whereas the eastern segment (outer foreland province) is devoid of significant glacial-related deposits, the central segment (inner foreland and fold-and thrust belt provinces) shows evidence of repeated advances and retreats of the Magellan glacier. An important moraine ridge complex, probably corresponding to the glacial advance "D"of Clapperton et al., has been seismically imaged in the central segment, as well as an older, large bank of ice distal sediments that have been interpreted as proglacial lake deposits, which show evident signs of repeated glacial erosions. Ice-contact features in the form of frontal moraine complexes made up of dipping foreset strata are present in the fjord-like, western segment of the Strait (Cordillera province), along with their related ice-proximal and ice-distal facies. Eventually, the occurrence of preglacial sediments tectonized by the Magallanes-Fagnano transform fault has been reported in the same segment. This fact, which is supported by small outcrops reported in the updated geologic map, if substantiated by further investigations (i.e. advanced seismic reprocessing, sea bottom samplings), would prove the relatively young age (Late Miocene?) of the Magallanes-Fagnano transform fault

Geomorphology and sedimentology of Porto Pino, SW Sardinia, Western Mediterranean

This paper presents a detailed (1:4000) geomorphological, sedimentological and ecological map of a Mediterranean microtidal wave-dominated beach system and adjacent inner shelf. This map is an innovative cartographic product that integrates a range of processes of present and past timeframes. It is part of a larger cartography on the coastal geomorphology of Sardinia (Italy) aiming to facilitate coastal management practices and future scientific research. The study area is located in SW Sardinia (Italy), and focuses on Porto Pino beach, an important tourist destination of semi-pristine nature, facing environmental pressures common to many coastal Mediterranean settings. In this context, the main human impact on coastal dune habitats is described and a full environmental characterization of the beach system is presented

Geomorphology, beach classification and seasonal morphodynamic transition of a Mediterranean gravel beach (Sardinia, Gulf of Cagliari)

This paper presents an innovative multi-thematic map (1:2500) that integrates morpho-sedimentological data, hydrodynamic processes, seasonal morphodynamic transitions and the distribution of the benthic habitat of a Mediterranean microtidal, wave-dominated gravel beach system. It is part of a larger cartography of coastal areas, and is based on an interdisciplinary sea-land approach that is applicable worldwide and aims to facilitate coastal management practices and future scientific research. The applications to coastal management include: the facilitation of coastal vulnerability assessments; easy-to-access, up-to-date digital geospatial data; and baseline studies for the future assessment and monitoring of environmental changes. The main environmental features that control the marine processes of this gravel beach appear to be linked to geological and morphological contexts such as the presence of the river mouth, the outcropping of a beach-rock along the coastline, the deposition of gravelly sediment in the beachface and the seagrass cover

Natural vs. Anthropic Influence on the Multidecadal Shoreline Changes of Mediterranean Urban Beaches: Lessons from the Gulf of Cagliari (Sardinia)

Urban Mediterranean beaches are often characterized by a fragile and unstable equilibrium that can be easily altered by ongoing climate change and by the increase in human pressure. This may pose serious threats to the survival of beach systems that cannot accommodate these modifications. In this paper, the spatio-temporal shift of the shoreline was investigated along two urban beaches in the Gulf of Cagliari (Poetto and Giorgino; southern Sardinia, western Mediterranean Sea) across a time frame of 62 years (1954–2016). The Digital Shoreline Analysis System (DSAS) ArcGIS™ extension was used to extract different statistical parameters which allowed us to quantify the erosion and accretion rates. These data were further examined in relation to a number of anthropic and natural forcings in order to disentangle the factors controlling shoreline evolution. Eight sectors with interchanging net erosive and accretion trends were identified along the Poetto and Giorgino beaches. In six decades, some sectors of the two study sites appeared to have undergone great shoreline modification as a result of the intense anthropogenic activities impacting these coastal areas. The westernmost portions of both beaches were found to be the most vulnerable to erosion processes; such conditions were likely controlled by the interplaying of local hydrodynamics and by the intense coastal development which affected these sectors. The highest retreat rates (mean end point rate (EPR) = −0.51/year) were recorded in the western limit of Giorgino beach. Along the western limit of Poetto beach, EPR erosion rates (mean EPR = −2.92/year) considerably increased in the years after the artificial beach nourishment carried out in 2002, suggesting that the majority of the nourished material was lost offshore or partly redistributed along the beach. Coastal structures, urban development, river catchment modification, industrial and port activities, beach cleaning and touristic and recreational activities have been identified as the ongoing causes of coastal alteration. If these factors remain constant, under projected climate change scenarios, these beaches are at risk of further increased flooding and erosion. In this context, the application of DSAS appeared as an essential tool, supporting a monitoring system able to provide understanding and, potentially, predictions of the short- to long-term evolution of these beach system

Infralittoral ostracode fauna of Porto Puddu Rias (northern Sardinia)

The knowledge of the infralittoral ostracodes presents an increasing interest since it is an essential tool for several fields of research such as human impact of the coastal environments, including environmental monitoring, geoarchaeology and reconstruction of ancient shorelines. The study of the infralittoral ostracode fauna of a small bay of northern Sardinia may represent an useful piece of this knowledge. This bay near Porto Puddu is characterized by shallow seafloors presenting wide vegetated areas, progression of the shoreline and seasonal strem (southern sector). Moreover, its water column is conditioned by winds along the year (Astraldi et al., 1980)

Glacigenic features and Tertiary stratigraphy of the Magellan Strait (Southern Chile)

The seismostratigraphic and structural analysis of the whole length of the Magellan Strait, from the Atlantic to the Pacific entrance is for first time illustrated on the basis of multichannel seismic (MCS) profiles. The Strait crosses a geologically complex region that includes different morphotectonic provinces, and has been subdivided into three distinct segments, eastern (Atlantic), central, and western (Pacific), being each segment characterized by peculiar sedimentary and tectonic architectures. The MCS profiles shed light on the subsurface of the region in particular on the Quaternary and Tertiary features. In the foreland basin province, the MCS profiles imaged an almost undeformed structural and stratigraphic frame with very thick Cretaceous to Tertiary package. Seismic evidence of deformation of the foreland units occurs in the fold-and-thrust belt province. Along the Cordillera province, the Magallanes-Fagnano transform fault exerts an important morpho-tectonic control that strongly conditions its bathymetric profile. The seismic profiles also highlighted a number of depositional features linked to the up to 150 m thick sedimentary record of the glacial cycles. Whereas the eastern segment (outer foreland province) is devoid of significant glacial-related deposits, the central segment (inner foreland and fold-and thrust belt provinces) shows evidence of repeated advances and retreats of the Magellan glacier. An important moraine ridge complex, probably corresponding to the glacial advance "D"of Clapperton et al., has been seismically imaged in the central segment, as well as an older, large bank of ice distal sediments that have been interpreted as proglacial lake deposits, which show evident signs of repeated glacial erosions. Ice-contact features in the form of frontal moraine complexes made up of dipping foreset strata are present in the fjord-like, western segment of the Strait (Cordillera province), along with their related ice-proximal and ice-distal facies. Eventually, the occurrence of preglacial sediments tectonized by the Magallanes-Fagnano transform fault has been reported in the same segment. This fact, which is supported by small outcrops reported in the updated geologic map, if substantiated by further investigations (i.e. advanced seismic reprocessing, sea bottom samplings), would prove the relatively young age (Late Miocene?) of the Magallanes-Fagnano transform fault

Geomorphology of four wave-dominated microtidal Mediterranean beach systems with Posidonia oceanica meadow: a case study of the Northern Sardinia coast

The results of this geomorphological study, which focuses on four Mediterranean embayed microtidal wave-dominated beach systems and the related inner shelf, are reported on a detailed geomorphological map (1:12,000 scale). The study area is located between Punta di Li Francesi and Lu Poltiddolu in NW Sardinia, W of the Strait of Bonifacio. The Main Map presents geomorphological, sedimentological, hydrodynamical and ecological (underwater vegetation) features indicated in nine sections of the map legend. Integrative maps (1:40,000 scale) of side-scan sonar surveys, sedimentary facies, survey routes and sampling point locations are also represented on the Main Map. This work summarizes 25 years of historical geomorphological datasets and can be considered as a reference for future comparisons of the study area as indicated by current European legislation. In addition to the scientific value of this study, the proposed map can be an important tool for coastal, beach and inner shelf management

Morpho-sedimentology of a Mediterranean microtidal embayed wave dominated beach system and related inner shelf with <i>Posidonia oceanica</i> meadows: the SE Sardinian coast

<p>This article presents a morpho-sedimentological map of a Mediterranean embayed microtidal wave-dominated beach system and related inner shelf. The study area is located between Capo Boi and the Torre de su Fenugu sector, and focuses on Solanas beach in SE Sardinia. All of the collected data were processed to draw a main 1:7,000 scale map, which shows the general characteristics of the entire area, including its hydrodynamic, morphological, and sedimentological features (distribution of siliciclastic and biogenic/bioclastic sediments), rocky outcrops, beach rocks, and marine phanerogam meadow coverage (mainly <i>Posidonia oceanica</i>). Several secondary maps such as routes and paths, side-scan sonar photomosaic interpretations, and sedimentary facies have also been included. In addition to its scientific value, the map can be an important tool for beach management purposes.</p