Examinando por Autor "Baneschi, Ilaria"

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  • Artículo
    Embargado
    Holocene Beach Ridges and Coastal Evolution in the Cabo Raso Bay (Atlantic Patagonian Coast, Argentina)
    (2011) Ribolini, Adriano; Aguirre, Marina L.; Baneschi, Ilaria; Consoloni, Ilaria; Fucks, Enrique; Isola, Ilaria; Mazzarini, Francesco; Pappalardo, Marta; Zanchetta, Giovanni; Bini, Monica
    The Holocene evolution of the Cabo Raso bay (Atlantic Patagonian coast) was reconstructed by means of geomorphological, stratigraphic, and palaeontological analyses, assisted by radiocarbon dating. Six beach ridges were individuated and mapped in the field, as well as some rocky erosional landforms,e.g.,inner margins of marine terraces. Thanks to quarry sections, the internal structure of beach ridges, their relationship with continental deposits, and the fossil contents were determined. Two specimens ofAulacomya atraandBrachidontes purpuratuswere radiocarbon dated at 6055 and 4500 ± 20 YBP, respectively. The bedrock outcrops at the base of an analysed section allowed us to associate the age of the samples collected to the elevation of the marine transgression surface upon which the entire deposit rests. Because a beach ridge is a regressive form, the elevation of the base of the dated deposit was assumed to be equivalent to or slightly lower than the maximum sea-level stationing, represented by the inner margin of the coheval marine terrace. The altimetric correlation between the base of the beach ridge dated at 6055 ± 20 YBP and the inner margin of the corresponding marine terraces allowed us to constrain the maximum Holocene marine transgression to about 3 to 2m above sea level. This elevation for the maximum Holocene transgression is lower than that shown by most of the previous data for Patagonian coast, but it shows a crude agreement with recent estimates coming from geophysical models that report, for this area, a departure from the eustatic value of sea level, mainly caused by glacioisostatic process. This means that the employment of marine erosional landforms, associated with other multisource field data, proved to be determinant for reconstructing the sea-level variation in the Patagonian coast.
  • Artículo
    Embargado
    New insights on the Holocene marine transgression in the Bahía Camarones (Chubut, Argentina)
    (2012) Zanchetta, Giovanni; Consoloni, Ilaria; Isola, Ilaria; Pappalardo, Marta; Ribolini, Adriano; Aguirre, Marina; Fucks, Enrique; Baneschi, Ilaria; Bini, Monica; Ragaini, Luca; Terrasi, Filippo; Boretto, Gabriella
    The stratigraphic reconstruction of the northern sector of theBahía Camarones (Chubut, Argentina) allowed to improve ourunderstanding of the Holocene marine transgression in the area.The first phase of the maximum of the transgression, is interpretedas dominated by the high rate of eustatic rise of sea level until ca.6-7 ka BP possiblyassociated to sedimentary starvation as suggestedby fossil accumulation. After this first phase, the general trend indi-cates a progressive fall of the relative sea level after the MiddleHolocene high stand as documented in other parts of south Amer-ica Atlantic coast. Our data, coupled with the robust radiocarbondata set available for the area from literature, indicate three mainlocal steps of coastal aggradation between ca. 6600 and 5400 yr BP(ca. 7000-5600 yr cal BP), ca. 3300 and 2000 yr BP (ca. 3100-1700 yrcal BP), and ca. 1300-500 yr BP (ca. 1000-300 yr cal BP). A signifi-cant age gap in coastal aggradation is present between ca. 5300 and4400 yr BP (ca. 5600-4500 yr cal BP), and perhaps between ca 2000and 1300 yr BP (ca. 1700-1000 yr cal BP). These can be linked tophases of local sea level fall and/or phases of sedimentary starvationand/or changes in drift transport which can have produced localcoastal cannibalization. However, no conclusive data can beadvanced. Data obtained from careful measurements of sea levelmarkers represented by the top of marsh and fluvial terraces indi-cate lower values for the sea level estimation compared with thedata set previously proposed for the area. This stigmatizes the factthat field-oriented works are still the priority in the Patagonia coastalong with accurate age measurement, especially for obtaining thefundamental information we need for predicting the environmentalimpact, in these coastal areas,from accelerate sea level rise as effectof global warming.