1,721,094 research outputs found
Man Made Deltas
Full text linkThe review of geochronological and historical data documents that the largest southern European deltas formed almost synchronously during two short intervals of enhanced anthropic pressure on landscapes, respectively during the Roman Empire and the Little Ice Age. These growth phases, that occurred under contrasting climatic regimes, were both followed by generalized delta retreat, driven by two markedly different reasons: after the Romans, the fall of the population and new afforestation let soil erosion in river catchments return to natural background levels; since the industrial revolution, instead, flow regulation through river dams overkill a still increasing sediment production in catchment basins. In this second case, furthermore, the effect of a reduced sediment flux to the coasts is amplified by the sinking of modern deltas, due to land subsidence and sea level rise, that hampers delta outbuilding and increases the vulnerability of coastal zone to marine erosion and flooding
Data is the new sex. Forme di data intimacy nel design dell’informazione
No full textLa moderna emancipazione della sessualità verso una condizione di desiderio sospeso, consapevole, non istintuale, che rifiuta la subitaneità e l’orgasmocentrismo, suggerisce un rinnovato utilizzo del concetto di eros nella società post digitale e nella viscerale sete di conoscenza che la permea. Il rapporto erotico che culmina con il momento di massimo raggiungimento del piacere, cioè, oggi rivede le sue priorità e l’identità dell’ipotetico ’altro’ con cui entriamo in contatto in questa permanente ricerca di piacere diventa olistica, multidimensionale, inorganica e spesso immateriale. Se secondo le teorie post umaniste alla condizione relazionale di erotismo – neutrale – verso il divino e l’animale si affianca il rapporto di desiderio verso l’oggetto, nello specifico la macchina , oggi il rapporto con l’altro si complica e il significato di ’altro’ supera l’entità ontologica degli esseri viventi e delle macchine: anche il dato diventa una ‘instance’ e un’entità separata con la quale interagire intimamente e che manifesta qualità diverse dalle categorie citate. Il dato in quest’ottica è protagonista di operazioni di scoperta, affezione, desiderio che si verificano in sistemi autopoietici fondati su una nuova dimensione relazionale. L’erotismo del dato supera l’idea di abbattimento delle barriere tra gli esseri umani attraverso le media technologies e le stimolazioni sensoriali sinestetiche poiché vaglia nuovi approcci costruttivi del rapporto tra il soggetto umano e la creazione di informazioni. Questo rapporto erotico più consapevole, maturo, talvolta indiretto con il dato, trova una possibile definizione nel concetto di ‘intimità’ indagato dalla psicologia per descrivere il rapporto tra organico e non organico. Secondo Jacques Lacan il termine intimità descrive una condizione relazionale non necessariamente associata ai desideri e alle passioni fisiche e sessuali ma più propriamente una connessione emotiva, sensoriale, spirituale o fisica profonda e stretta tra due entità. Applicato al rapporto con il dato, il concetto di intimità ammette la possibilità di costruire connessioni che superano i costrutti sociali e culturali e che proiettano l’essere umano verso una condizione di trascendenza dalla stessa natura umana e ontologia materiale, demistificando la centralità dell’uomo e individuando nuove forme di relazione con il non-umano. Nel presente saggio si indagheranno queste forme di erotismo che vedono interagire il dato – o meglio le sue visualizzazioni – e l’essere umano, protagonisti di una pletora di relazioni intime che nascono da un lato dall’imperante e pervasiva società dei dati e dei processi di dataficazione, dall’altro da una continua ricerca di conoscenza e di relazione che in uno scenario postumano coinvolge anche elementi intangibili informativi, con cui si crea un’entropia spontanea, e una relazione dinamica e dalle configurazioni eterogenee. L’analisi di questa eterogeneità condurrà all’identificazione di rapporti intimi con il dato, ad una data intimacy olistica descritta attraverso parallelismi con le parafilie e ispirata dalle riflessioni condotte in psicanalisi da Sigmund Freud e Jacques Lacan e alle teorie sociali di filosofi come e alle teorie sociali di filosofi come Friedrich Nietzsche e Ferdinand Tonnies che, come si vedrà, saranno alla base del tipo di relazione intima tra persona e dato
Large-scale single incised valley from a small catchment basin on the western Adriatic margin (central Mediterranean Sea)
No full textThe Manfredonia Incised Valley (MIV) is a huge erosional feature buried below the Apulian shelf, on the western side of the Adriatic margin. The incision extends more than 60 km eastward, from the Tavoliere Plain to the outer shelf, not reaching the shelf edge. High-resolution chirp sonar profiles allow reconstruction of the morphology of the incision and its correlation at regional scale. The MIV records a single episode of incision, induced by the last glacial–interglacial sea level fall that forced the rivers draining the Tavoliere Plain to advance basinward, reaching their maximum extent at the peak of the Last Glacial Maximum. The valley was filled during a relatively short interval of about 10,000 yr during the Late Pleistocene–Holocene sea level rise and almost leveled-off at the time of maximum marine ingression, possibly recording the short-term climatic fluctuations that occurred. The accommodation space generated by the lowstand incision was exploited during the following interval of sea level rise by very high rates of sediment supply that allowed the preservation of up to 45 m of valley fill. High-resolution chirp sonar profiles highlight stratal geometries that are consistent with a typical transgressive valley fill of an estuary environment, including bay-head deltas, central basin and distal barrier-island deposits, organized in a backstepping configuration. The highest complexity of the valley fill is reached in the shallowest and most proximal area, where a kilometric prograding wedge formed during a period dominated by riverine input, possibly connected to high precipitation rates. Based on the depth of the valley margins during this interval, the fill was likely isochronous with the formation of sapropel S1 in the Mediterranean region and may have recorded significant fluctuations within the hydrological cycle
Local marine reservoir age (δr) reconstructed based on the tsunami deposit from Pangani bay (Tanzania)
Full text linkQuantifying the local marine reservoir age (ΔR) and its change over time is critical for precise radiocarbon calibration of marine samples and for the study of the ocean carbon cycle. ΔR values are scarce for the African coast facing the Indian Ocean, and the few values available were obtained from pre-bomb shells collected during the 19th century. Here, the ΔR value for calibrated year 1110 ± 25 (1σ) CE was reconstructed from radiocarbon dating and Bayesian analysis of marine and terrestrial materials coexisting in a tsunami deposit discovered in Pangani Bay (Tanzania, western Indian Ocean coast). The reconstructed ΔR of –8 ± 40 (1σ, n = 3) is similar to pre-bomb regional estimates and provides new information to investigate regional ΔR change over time. The Bayesian analysis of the dated samples revises the age of the tsunami event found in Pangani Bay to 1064–1157 cal CE (95.4% confidence level) or 1110 ± 25 (1σ) cal CE, about one century younger compared to the previous estimate. Our results indicate that the new ΔR value and the proposed calibration approach can be used to refine existing chronologies in the region, with implications for paleo-environmental reconstructions and archaeological studies of Early Swahili societies
Onshore to offshore anatomy of a late Quaternary source-to-sink system (Po Plain–Adriatic Sea, Italy)
Full text linkIn understanding the evolution of siliciclastic systems, Late Quaternary analogs may enable reliable predictive models of facies-tract architecture. The Po Plain–Adriatic Sea system, where a wealth of research has been conducted during the last 20 years, represents one of the most intensively investigated late Quaternary successions. With the aid of a chronologically well-constrained stratigraphy, paleoenvironmental evolution is tracked for the first time from fluvial to deep-marine realms, over 1000 km in length. Vertical stacking trends (onshore) and stratal terminations (offshore) are the key observations that allow identification of surfaces with sequence-stratigraphic significance (systems tract boundaries) in the distinct segments of the system. Recurring motifs in stratigraphic architecture, showing tight coupling of sedimentary responses among source area, catchment basin, and coastal and marine depocenters, reveal a cyclicity driven by glacio-eustatic fluctuations in the Milankovitch band. Due to high rates of subsidence, middle Pleistocene forced regressive systems tracts are exceptionally expanded, and the MIS5e–MIS2 interval (Late Pleistocene) preserves a nearly continuous record of fourth-order (100 kyr) stepwise sea-level fall. The stratigraphic architecture of Last Glacial Maximum deposits highlights the genetic relations between channel–belt development, pedogenesis, and sediment delivery to the lowstand delta, through narrow incised-valley conduits. The Late glacial-Holocene succession records the last episode of sea-level rise and stabilization through well-developed patterns of shoreline transgression/regression (TST/HST) that can be readily traced updip, from offshore to onshore locations. Architectural styles across the whole system reflect a dominance of allogenic forcing in the TST, as opposed to a predominantly autogenic control on stratigraphic development in the HST. External drivers of facies architecture were also effective on millennial timescales: the Younger Dryas cold reversal, which marks the transgressive surface on land, records a short-lived episode of subaqueous progradation that is correlative onshore with widespread, immature paleosol development and small-sized channel–belt formation. Quantitative assessment of sediment budgets over different time intervals requires precise positioning of the key bounding surfaces. Based on this approach, we outline for the first time over the entire Po–Adriatic Basin an estimate of the sediment volumes stored in each systems tract
Environmental controls on the generation of submarine landslides in Arctic fjords: Insight from Pangnirtung Fjord, Baffin Island, Nunavut
No full textHigh-latitude fjords are susceptible to hazardous subaerial and submarine mass movements such as rock avalanches and landslides. Geophysical surveys in the fjords of Baffin Island (Nunavut) have shown widespread evidence of submarine landslides, but their timing and triggers remain relatively unconstrained, limiting our ability to understand the environmental controls on the wide range of landslides occurring in high latitude fjords. Using bathymetric, sub-bottom, and sediment core data, this study seeks to generate a comprehensive understanding of the distribution, morphology, lithology, and timing of submarine landslides in Pangnirtung Fjord (SE Baffin Island, Nunavut). These results are used to evaluate the influence of different environmental controls on the generation of submarine landslides in Arctic fjords. We identified 180 near-surface submarine landslides, most of which are relatively small (∼ 0.13 km2), with elongated depletion zones and wide deposits dispersed along the basin floor of the fjord. Landslide ages, calculated from radiocarbon dating and 210Pb/137Cs activities, indicate that 8 of the 11 dated landslides occurred in the last 200 years. Four types of environmental controls were identified, which are believed to have preconditioned or triggered the observed landslides: 1) 51% of landslides, by area, are associated with subaerial sources and extend offshore of debris flow channels and fans; 2) 23% are initiated in shallow-water (< 40 m), are non-subaerially influenced, and may have been triggered by nearshore processes and sea-ice loading; 3) 13% are located in deeper waters (>40 m) and associated with sills and moraines, suggesting they are older deposits associated with the retreat of the ice sheet in the fjord; and 4) 13% are offshore of river deltas, likely associated with delta progradation; they form the largest landslide deposits in the fjord. This research suggests that the main triggers for submarine landslides in high-latitude fjords are climatically influenced (rainfall, floods, subaerial debris flows, and sea ice loading). Consequently, the predicted increase in the frequency of subaerial debris flows and river floods due to anthropogenic climate change will likely result in an increase in the recurrence of these types of submarine landslides. Additional monitoring efforts will be then needed to fully evaluate how future climate will impact the submarine landslide hazard across the Arctic
Pliocene–Quaternary contourite depositional system along the south-western Adriatic margin: changes in sedimentary stacking pattern and associated bottom currents
No full textThe Pliocene–Quaternary history of the south-western Adriatic margin, represented by a complex contourite depositional system, records the palaeoceanography of the basin and the interactions between oceanographic processes and the uneven slope morphology that resulted from tectonic deformation. Three main stages can be recognized: (1) during the Pliocene, a giant sediment drift formed on the southern flank of the slope-transverse Gondola anticline that focused and accelerated the flow of slope-parallel bottom currents; (2) since the early to middle Pleistocene transition, a reorganization of bottom-current pathways led to a sharp change in the sedimentary architecture of the margin that became dominated by the growth of contourite deposits; (3) as of 350 ka, landward-migrating contourites on the outer shelf (less than 120 m water depth) reflect the presence of bottom currents also in shallow waters. This analysis of the sedimentary stacking pattern of the contourite depositional system that developed along the south-western Adriatic margin since the Pliocene enables disentangling the processes that controlled changes in bottom-current activity, demonstrating that bottom-current deposits constitute the bulk of depositional sequences at the Milankovitch timescale
Bottom currents, submarine mass failures and halokinesis at the toe of the Sigsbee Escarpment (Gulf of Mexico) : Contrasting regimes during lowstand and highstand conditions?
Full text linkWe are grateful to BP for the provision of both sea-floor and subsurface data. We thank the journal editor Michele Rebesco for his continuous support, and Lorena Moscardelli, Daniele Casalbore and an anonymous reviewer for their detailed and constructive comments, which have allowed us to considerably improve the manuscript.Peer reviewe
Ercolano M. R., Faino L., Melito S., Sanseverino W., Roma G., Maselli V., Stupka E., Frusciante L.. “SGD Database: a new tool for Solanaceae resistance genes analysis” PAA/Solanaceae Genomics Meeting and Biodiversity, 23/27 Luglio pag. 125 (2006).
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