Papers by Alessandro Fontana
PERCORSI NEL PASSATO. MISCELLANEA DI STUDI PER I 35 ANNI DEL GRAVO E I 25 ANNI DELLA FONDAZIONE COLLUTO, 2018
Archeological structures have been widely used to infer the past relative sea level (RSL). Howeve... more Archeological structures have been widely used to infer the past relative sea level (RSL). However, pre-Classical settlement linked to sea level are rare and their use is generally limited, also for the dramatic changes occurred in the coastal landscape. An exception is represented by the lagoon belt east of Venice, where many Bronze- Age settlements are now exposed, thanks to the land reclamation carried out in the 20th century. The analysis or published information and of new stratigraphic-chronologic data allow to reconstruct sea-level rise. In addition, three different settlements categories are recognized: a) sites on Holocene fluvial ridges; b) sites on the alluvial plain of the Last Glacial Maximum settled along a groundwater-fed river; c) sites in the lagoon. Since 6000 years ago, the lagoon environment was already partly comparable to modern one in size, with the RSL around -4 m asl. At about 1800 BC, RSL was comprised between -3 and -2.7 m asl, whilst at the transition between recent and final Bronze Age (1250-1100 BCE) it was probably at -2.0 ± 0.6 m asl. The investigated settlements were abandoned during the final Bronze Age, or slightly before. At the end of Bronze Age the sea level seems to have been risen progressively, suggesting that this process was not strongly responsible of the demission phase of the coastal sites. It is likely that socio-cultural changes or other environmental factors should be considered.
Remote sensing, Feb 22, 2024
The interpretation of high-resolution remote-sensed data (i.e., LiDAR-derived DTMs, aerial photos... more The interpretation of high-resolution remote-sensed data (i.e., LiDAR-derived DTMs, aerial photos and satellite images), compared with ground-penetrating radar surveys, historical cartography, geomorphological surveys and stratigraphic data, allowed us to map a large system of dunes near the Grado-Marano Lagoon (NE Italy) and reconstruct its evolution. Remote sensing investigations allowed us to recognize, map and interpret the sandy reliefs as a field of continental aeolian landforms extending for over 15 km 2 and consisting of parabolic dunes elongated in the WSW direction. Radar soundings, together with the description of stratigraphic sections and cores, documented the internal clinostratification of the dunes, supporting their aeolian origin. Radiocarbon dating documents that the dunes formed 22 ka ago, at the end of the Last Glacial Maximum, and probably evolved until the first part of the Late Glacial, when vegetation was scarce. The landforms were fed by the sands blown from a paleochannel of Isonzo River flowing eastward of the dune's field and blown by Bora. This is a very strong katabatic wind, still characterizing the area, but that was likely much stronger during last glaciation, when it was probably sustained by a stronger wind pattern in Central Europe.
EGU General Assembly Conference Abstracts, Apr 1, 2018
Earth-Science Reviews, Apr 1, 2016
A review of 914 Relative Sea-Level (RSL) data-points has resulted in the first quality-controlled... more A review of 914 Relative Sea-Level (RSL) data-points has resulted in the first quality-controlled database constraining the Holocene sea-level histories of the western Mediterranean Sea
EGUGA, Apr 1, 2015
From the early days of radiocarbon dating, the standard sample treatment has involved removal of ... more From the early days of radiocarbon dating, the standard sample treatment has involved removal of contamination from carbonates and humic acids by washes in acid and base, respectively. A modification of this acid-base-acid (ABA) method has been suggested, especially for material older than 20,000 yr. However, the criticism of ABA and application of a more aggressive oxidizing method, such as wet oxidation (ABOX) or cellulose extraction, might only be needed in some special cases, for example, in the case of poorly preserved or chemically treated wood. Separation of cellulose seems to be the ultimate solution; however, it is not always applicable when samples contain small amounts of wood. As a part of studies focusing on the chronology of late Pleistocene sedimentary processes in the Venetian–Friulian Plain and Carnic Alps (NE Italy), 14C analyses were performed on old wood samples found in sedimentary deposits of pre-Last Glacial Maximum (LGM) age. Wood samples were treated by five methods: ABA, two modified ABA treatments (ABOX and ABA+Bleach), as well as two different cellulose separations. Infrared spectra of treated samples and 14C results show that in most cases the ABA method is sufficient in removing the contamination of naturally deposited wood, even when the wood is of very old age.
International Journal of Earth Sciences, Apr 9, 2018
Our research is aimed at estimating the vertical deformation affecting late Quaternary units accu... more Our research is aimed at estimating the vertical deformation affecting late Quaternary units accumulated into the foreland basin of the Northern Apennines chain. Beneath the study alluvial plain, compressive fault-fold structures are seismically active. We reconstructed the stratigraphic architecture and the depositional evolution of the alluvial deposits, which accumulated in the first 40 m of subsurface, through the last 45,000 years, from before the Last Glacial Maximum to the present. A 58 km-long stratigraphic profile was correlated from the foothill belt near Bologna to the vicinity of the Po River. The analysis of the profile documents subsidence movements through the last 12,000 years, exceeding -18 m in syncline areas, with subsidence rates of at least 1.5 m/ka. Anticlines areas experienced a much lower subsidence than the syncline ones.
Cambridge University Press eBooks, May 18, 2023
Quaternary International, Feb 1, 2020
<p>Continental aeolian dunes are a major feature in many alluvial plains of Central... more <p>Continental aeolian dunes are a major feature in many alluvial plains of Central and Western Europe, whereas they are completely unknown in the alluvial environments of northern Italy. Thanks to the analysis of satellite images, aerial photos, Lidar-derived DEMs, Ground Probing Radar (GPR) profiles and field survey we identified a large system of dunes formed in the LGM in NE Italy. The study area is located in the distal portion of the Friulian Plain, between the city of Aquileia and the Grado Lagoon, where a series of small elongated sandy reliefs is present and locally called “dunes of Belvedere – San Marco”. The zone is part of the distal sector of the megafan of Isonzo River and is surrounded by lagoon areas reclaimed since the 19<sup>th</sup> century. This peculiar geographical position led many scholars to consider them as Holocene coastal dunes.</p><p>The investigated landforms cover an area of about 25 km<sup>2</sup> and they are mainly elongated in the ENE-WSW direction. The dunes have been largely quarried along history, but the highest crests reach up to 10 m above sea level (asl), in contrast with the surrounding reclaimed coastal plain (-1 m asl). The deposits consist of sands ranging from fine to medium-coarse. Near the dune’s ridges, concretions of cemented sand are abundant and largely exposed by ploughing practices. In outcrops and GPR radargrams the cross sections document an internal structure made of 20-30° inclined foresets, a few centimeters thick. The investigated dunes lay over the LGM alluvial plain forming the distal sector of Isonzo River and their base is radiocarbon dated to about 21 ka cal BP. Considering that vegetation should be scarce during the formation of the dunes, it is likely that they were built between the end of the LGM and the first stadial phases of Late Glacial.</p><p>The new data allow to interpret the Belvedere – San Marco reliefs as a system of parabolic dunes consisting of parallel and linear ridges, merging on the lee side in frontal lobes. They currently represent the largest and most complex continental aeolian dunes system in Italian Peninsula. Moreover, the orientation of the dunes is concordant with that of Bora, a katabatic wind which blows in Northern Adriatic from ENE and even today can reach peak velocity of 40 m/s. Similar wind, supported by the North European and Alpine ice caps could blow stronger and more frequently during the onset of deglaciation, when sandy sediment was largely available, supplied by braided channels of Isonzo River.</p><p>This discovery underlines the importance of wind-driven processes in the evolution of alluvial plain in northern Italy and suggests the presence of other continental dune systems, also on the seafloor of the Northern Adriatic, which was part of the continental plain until Late Glacial and was then submerged by sea-level rise.</p>
EGU General Assembly Conference Abstracts, Apr 1, 2018
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Papers by Alessandro Fontana
ha costituito un ottimo luogo per lo stabilirsi di insediamenti
nel corso delle prime fasi del Neolitico. La sorveglianza
archeologica, effettuata nel 2011 lungo un tratto di
metanodotto SNAM, ha consentito di individuare nuove
evidenze neolitiche a Cargnacco, non lontano in linea d'aria dal
ben noto sito di Sammardenchia. Le indagini hanno
interessato purtroppo solo un'area molto limitata nell'ambito
del tracciato della linea di posa delle tubature del gas; la
sorveglianza non ha invece rilevato altre evidenze
archeologiche lungo il tracciato del metanodotto. Raccolte di superficie di materiali in selce nei terreni circostanti
confermano comunque la scoperta, suggerendo la presenza di
un abitato neolitico esteso.
more info at: https://onlinelibrary.wiley.com/journal/10990763/under-canopy-airborne-lidar-future-prospects