[Show abstract][Hide abstract] ABSTRACT: A buried paleovalley system, up to 2 km wide and exceeding 50 m in relief, made up of multiple cross-cutting depressions incised into the Lower Pleistocene bedrock, is reported from the central Adriatic coastal plain at the mouth of Biferno River. Through a multi-proxy approach that included geomorphological, stratigraphic, sedimentological and paleontological (benthic foraminifers, ostracods and molluscs) investigations, the facies architecture of distinct, superposed valley fills is reconstructed and their relative chronology established along a transverse profile with extremely high data density (average borehole spacing 75 m). Regional tectonic uplift appears as the major controlling factor of initial (Middle Pleistocene) river down-cutting and paleovalley formation. In contrast, glacio-eustatic fluctuations drove fluvial-system response over the last 120 ky, when valley incision was primarily induced by the last glacial base-level lowering and climatic forcing. A fragmented record of coastal and shallow-marine deposits is available for the lower paleovalley fill, which is penetrated by a limited borehole dataset. Multiple erosion phases probably related to the post-MIS 5e sea-level fall are reconstructed from the upper paleovalley fill, where a buried fluvial terrace succession is identified a few tens of meters below the ground surface. The flat surfaces of two buried fluvial terraces suggest longer-term, stepped relative sea-level fall, and are correlated with fluvial incisions that took place possibly at the MIS 5/4 transition and at the MIS 3/2 transition, respectively. A laterally extensive gravel body developed on the valley floor during the Last Glacial Maximum. During the ensuing latest Pleistocene–early Holocene sea-level rise the Biferno paleovalley was transformed into an estuary. Upstream from the maximum shoreline ingression, the vertical succession of well-drained floodplain, poorly-drained floodplain, and swamp deposits evidences increasing marine influence in the estuary, in response to continuing sea-level rise. The interfluves were drowned around 8 cal. ky BP, when brackish conditions developed in the study area. Decreasing marine influence in the uppermost 15 m of the paleovalley fill suggests the onset of the modern delta: when the rate of sea-level rise was overwhelmed by sediment supply, delta progradation took place.
[Show abstract][Hide abstract] ABSTRACT: In 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.
No preview · Article · Oct 2015 · Earth-Science Reviews
[Show abstract][Hide abstract] ABSTRACT: Palaeosol-based correlations within the Late Pleistocene- Holocene alluvial succession along the Reno River, in the southern Po Plain, enabled the identification of depositional cycles falling in the sub-Milankovitch band. Each cycle, composed of overbank and fluvial facies capped by poorly to weakly developed palaeosols, is correlatable upstream to a single fluvial terrace in the Reno River valley and to an individual channel belt close to the valley outlet. Four cycles, dated to about 15-10 (c1), 10-5.5 (c2), 5.5-1.5 (c3) and <1.5 (c4) cal ky BP, respectively, were identified within the Ravenna subsynthem (AES8), an unconformity-bounded unit of the Geological Map of Italy to scale 1:50,000, corresponding to the post-Last Glacial Maximum deposits. This unit, typically wedge-shaped in coastal areas, where it consists of retrogradational (coastal plain and estuarine) deposits overlain by progradational (deltaic) facies, at the basin margin is a mud-dominated alluvial succession deposited atop laterally extensive fluvial-channel complexes. The base of AES8, correlatable to the transgressive surface identified in the coastal area, is a palaeosol dated to about 18-15 ky BP. The bounding surfaces of the high-frequency cycles are diachronous along the Reno longitudinal profile, and not necessary associated to remarkable lithological contrasts, but can be detected even in mud-dominated successions. Climate change likely exerted a major control in triggering alternating phases of river aggradation and degradation, with an increasing contribution of anthropogenic factors since the middle-late Holocene. Based on the correlation of 34 core logs and 33 well descriptions, with the aid of 71 radiocarbon dates, this study highlights to what extent palaeosols can represent powerful stratigraphic tools to identify cyclic patterns in alluvial successions, even at the millennial time scale.
No preview · Article · Jun 2015 · Italian Journal of Geosciences
[Show abstract][Hide abstract] ABSTRACT: A critical geoarchaeological approach, based on fully integrated archaeological, geomorphological and stratigraphic data, allowed for the identification of the palaeoenvironments, palaeotopography and urban growth patterns of Pisa (NW Italy) during the Etruscan (first half of the 5th century BC-first half of the 1st century BC) and Roman (second half of the 1st century BC-2nd century AD) periods. This powerful methodology, based on aerial and satellite images, electrical resistivity tomography, LiDAR, and core analysis, led to the reconstruction of landscape evolution, highlighting human-environment interactions. During the Etruscan and Roman periods, Pisa saw a fast urban expansion in a dense and unstable fluvial network. Wide portions of the city were characterised by poorly drained conditions until the 1st century AD, when the alluvial plain became well drained under increasing anthropogenic pressure (Roman Centuriatio). Poorly drained floodplains and channel-related backswamps represent the topographically lowest zones of the ancient Pisa. This city developed within an intricate pattern of palaeochannels, related to two main rivers: the palaeoArno, which flowed in proximity of its present position, and the former palaeoSerchio river, known as Auser flowing in the northern part of the city. Since Etruscan times, a mounded relief was formed in the historical city centre of Pisa, becoming wider and more prominent (up to ca. 2 m a.s.l.) during the Roman period, concomitant with a southward rapid expansion of the urban tissue. Nevertheless, the urban growth patterns substantially followed the Etruscan city’s fabric, with marked concentration of the urban structures (public and private buildings) and manufacturing sites on the northern relief, close to the Auser. The Auser River thus played a crucial role in the environmental and topographic evolution of the city area.
Full-text · Article · May 2015 · Journal of Archaeological Science
[Show abstract][Hide abstract] ABSTRACT: Litho-palaeoenvironmental Map of Italy during the Last Glacial maximum (22 ±2 ka cal BP) average air temperature of about 4.5°C lower than today; scale 1: ,000,000. Data: bed rocks; glaciers; loess; vertebrates; Ostracods; lakes; vegetation; Po plain; marine bathymetry; shore lines; Alpine foothills; sea surface temperature; archeology and active faults
ResearchGate. Available from: https://www.researchgate.net/profile/Lucilla_Capotondi/publications [accessed Mar 23, 2015].
[Show abstract][Hide abstract] ABSTRACT: A multi-proxy (stratigraphic, geomorphological, palynological, geophysical) study of mid-late Holocene deltaic-alluvial deposits beneath the Pisa Plain (Tuscany, Italy) reveals short-term enhances of fluvial activity under relative sea-level highstand (HST) conditions (last ~ 7000 cal yr BP). Early HST delta progradation led to the progressive infill of a broad lagoon area (~ 5000 cal yr BP), followed by the development of a stable alluvial depositional environment (~ 4000 cal yr BP). The intense phase of alluvial aggradation was punctuated by two events of enhanced fluvial incision that cut down to 10 m the underlying lagoonal substrate. The two erosive events, which reflect centennial-scale changes in the aggradation/degradation ratio, are chronologically constrained to the Eneolithic-Bronze age transition (~ 3800 cal yr BP) and to the Bronze–Iron age transition (2900-2800 cal yr BP), respectively.
Full-text · Article · Feb 2015 · Palaeogeography Palaeoclimatology Palaeoecology
[Show abstract][Hide abstract] ABSTRACT: Responses of ecosystems to environmental changes vary greatly across habitats, organisms and observational scales. The Quaternary fossil record of the Po Basin demonstrates that marine communities of the northern Adriatic re-emerged unchanged following the most recent glaciation, which lasted approximately 100 000 years. The Late Pleistocene and Holocene interglacial ecosystems were both dominated by the same species, species turnover rates approximated predictions of resampling models of a homogeneous system, and comparable bathymetric gradients in species composition, sample-level diversity, dominance and specimen abundance were observed in both time intervals. The interglacial Adriatic ecosystems appear to have been impervious to natural climate change either owing to their persistence during those long-term perturbations or their resilient recovery during interglacial phases of climate oscillations. By contrast, present-day communities of the northern Adriatic differ notably from their Holocene counterparts. The recent ecosystem shift stands in contrast to the long-term endurance of interglacial communities in face of climate-driven environmental changes.
Full-text · Article · Feb 2015 · Proceedings of the Royal Society B: Biological Sciences
[Show abstract][Hide abstract] ABSTRACT: Despite several studies have focused on the past bio-sedimentary response of the Mediterranean coastal areas to ancient seaport activities, only few geoarchaeological and palaeoecological data are available on strictly lacustrine harbours, to date. At the archaeological site of Magdala/Taricheae (Sea of Galilee, north Israel), an interdisciplinary study, combining ostracod fauna composition and shell chemistry with sedimentology, geochemistry of sediments and archaeological data, was undertaken on the sedimentary succession buried beneath the Roman harbour structures in correspondence of two key-sections. This approach provided detailed information about past environmental changes, otherwise not visible, into a high-resolution pottery-based chronological framework at the transition from a natural (pre-harbour) to anthropogenically influenced (harbour) lacustrine depositional setting.
Full-text · Article · Feb 2015 · Journal of Archaeological Science
[Show abstract][Hide abstract] ABSTRACT: The conservation of our architectural heritage, so vast and rich in historical and artistic terms, requires a multidisciplinary approach to understand the ongoing phenomena and to implement countermeasures against degradation factors and natural and anthropic risks. In this paper an integrated, geotechnical and structural, research for the investigation of the stability conditions of the Ninfeo di Genazzano is presented. The structure, which tracks back to the Renaissance and is attributed to Bramante, was built near Rome and is at present in ruins. The interpretation of the instability phenomena, already suggested in architectural studies of the past century, was carried out using a numerical approach based on the Finite Element method. Advanced constitutive laws were adopted to describe the key features of the mechanical behaviour of soil strata and masonry structures and of their mutual interaction. The comparison between the numerical results and the current conditions at the investigated site proves the predictive capabilities of the developed models and their potentiality in the context of evaluation and preservation activities of historical-architectural heritage.
No preview · Article · Jan 2015 · Rivista Italiana di Geotecnica
[Show abstract][Hide abstract] ABSTRACT: In marine settings, quantitative bathymetric models can be developed using various water depth proxies, including epibiont distribution, sedimentologic features, and the distribution of benthic taxa in time and space. Here, the late Quaternary bathymetric history of the Po coastal plain (Italy) has been reconstructed using mollusk samples from a network of 16 cores. Multiple analytical approaches have been applied in a comparative fashion. A direct ordination approach was used to estimate sample bathymetry using weighted averaging of genera with known preferred depth. Weighted averaging carries an advantage of analytical simplicity and produces direct ordination models expressed in environmentally meaningful units. Indirect ordination methods, based on depth estimates developed using posterioricalibrated ordination strategies (correspondence and detrended correspondence analysis calibrated against present-day bathymetric data), yielded results consistent with weighted averaging. Regardless of the choice of analytical methods, mollusk assemblages yielded bathymetric proxies congruent with independent sequence stratigraphic interpretations derived previously for both Late Pleistocene and Holocene transgressive-regressive cycles. The mollusk-derived proxies quantify spatial bathymetric gradients across the basin and local trends in absolute water depth in response to relative changes in sea level. However, for cores located in the most proximal part of the basin, mollusk-based ordinations failed to provide viable estimates due to inclusion of mixed marine and nonmarine mollusk faunas and scarcity of fossiliferous horizons necessary for adequate quantitative sampling. The multiple analytical approaches cross evaluated in this study consistently suggest that high-resolution quantitative bathymetric estimates can be derived for mollusk samples independent of stratigraphy for fully marine settings. When applied simultaneously to both samples and taxa, these approaches provide a viable strategy for quantifying stratigraphic and paleontological patterns and enhancing interpretations of basin-scale depositional systems.
Full-text · Article · Nov 2014 · The Journal of Geology
[Show abstract][Hide abstract] ABSTRACT: Many aquifers throughout Europe are contaminated by chlorinated solvents and the occurrence of these contaminants is commonly related to improper industrial or disposal practices taking place few decades ago. The region around the city of Ferrara (eastern Po plain, northern Italy) is an area strongly impacted by old industrial activities, with the occurrence of chlorinated compounds at several sites. A peculiarity which lumps together the contaminated sites identified around Ferrara is the predominant occurrence of Vinyl Chloride (VC), which in most of the cases represents the only chlorinated compound detected in groundwater, with the formation of VCA (Vinyl Chloride Alone) plumes. The City of Ferrara is located on a lowland alluvial plain, originated by the River Po, which consists of a cyclic alternation of aquifers and aquitards, down to a maximum depth of 200 m b.g.s. The study presented here is focused on the shallower confined regional aquifer, located between 15 and 50 m b.g.s. and exploited at several locations for drinkable water purposes. Within this aquifer, three sites strongly contaminated by chlorinated solvents were investigated by means of a multidisciplinary, hydrogeologic and stratigraphic approach. High-resolution sedimentological analyses from the Ferrara subsurface show the ubiquitous occurrence of peat-rich layers between 10 and 15 m depth, interpreted as early Holocene transgressive swamp deposits. An hydrogeologic investigation carried out along a vertical profile at one of the sources of contamination, proves that reductive dechlorination, from PCE and TCE to VC, takes place during the migration of DNAPLs through the fine peat-rich Holocene deposits, which locally act as a " reactor " for biodegradation. The results of this study highlight a significant criticality peculiar to the territory of Ferrara: the co-occurrence of peat-rich deposits and scattered sources of chlorinated solvents lead to recurring accumulation of VC, thus enhancing the degree of human health risk related to this kind of contamination.
[Show abstract][Hide abstract] ABSTRACT: One of the major issues when assessing soil contamination by inorganic substances is reliable determination of natural metal concentrations. Through integrated sedimentological, pedological and geochemical analyses of 1414 (topsoil/subsoil) samples from 707 sampling stations in the southern Po Plain (Italy), we document that the natural distribution of five potentially toxic metals (Cr, Ni, Cu, Zn and Pb) can be spatially predicted as a function of three major factors: source-rock composition, grain size variability and degree of soil weathering. Thirteen genetic and functional soil units (GFUs), each reflecting a unique combination of these three variables, are fingerprinted by distinctive geochemical signatures. Where sediment is supplied by ultramafic (ophiolite-rich) sources, the natural contents of Cr and Ni in soils almost invariably exceed the Italian threshold limits designated for contaminated lands (150mg/kg and 120mg/kg, respectively), with median values around twice the maximum permissible levels (345mg/kg for Cr and 207mg/kg for Ni in GFU B5). The original provenance signal is commonly confounded by soil texture, with general tendency toward higher metal concentrations in the finest-grained fractions. Once reliable natural metal concentrations in soils are established, the anthropogenic contribution can be promptly assessed by calculating metal enrichments in topsoil samples. The use of combined sedimentological and pedological criteria to fingerprint GFU geochemical composition is presented here as a new approach to enhance predictability of natural metal contents, with obvious positive feedbacks for legislative purposes and environmental protection. Particularly, natural metal concentrations inferred directly from a new type of pedogeochemical map, built according to the international guideline ISO 19258, are proposed as an efficient alternative to the pre-determined threshold values for soil contamination commonly established by the national regulations.
Full-text · Article · Sep 2014 · Science of The Total Environment
[Show abstract][Hide abstract] ABSTRACT: We present new data collected at the Fronte composite section near Taranto, where the Upper Pleistocene marine sedimentary succession is continuously exposed. Above a fossiliferous calcarenite yielding the “Senegalese” fauna, and abundant Cladocora, the 230Th/U age of which is consistent with Marine Isotope Stage (MIS) 5, a 6.25 m thick pelitic unit is characterized by lithologically homogeneous marine sediments in which stable oxygen isotope, micropaleontological and palynological analyses suggest a long and undisturbed sedimentary interval across the Marine Isotope Stage (MIS) 5.5 peak (plateau). High sedimentation rates and a successful paleomagnetic pilot study indicate the probability of locating brief chronostratigraphic events useful for correlation with both continental and marine successions elsewhere. These results show the composite section to be a very promising candidate in the search for the Upper Pleistocene global boundary stratotype section and point (GSSP).
Full-text · Article · Sep 2014 · Quaternary International
[Show abstract][Hide abstract] ABSTRACT: The Fronte Section, a well-exposed stratigraphic succession from southern Italy (Taranto area), provides an uninterrupted marine sedimentary record of MIS 5e. At this location, a highly expanded (8.5 m thick) stratigraphic succession, unconformably overlying Middle Pleistocene marine clay deposits, provides evidence for sea-level fluctuations during the Last Interglacial. An integrated study of Fronte Section, including facies analysis, detailed macrofaunal and meiofaunal characterization, and sequence stratigraphy, is presented. The occurrence of Persististrombus latus (= Strombus bubonius) and other warm-water indicators (“Senegalaise” – “Senegalian” - guests of Gignoux, 1913), together with the presence of the dinocyst Polysphaeridium zoharyi and ten U-series dates on Cladocora caespitosa samples, permit an unequivocal MIS 5e age assignment to the upper part of the study succession. Above a stratigraphic unconformity marked by the boring coastal-lagoonal bivalve Pholas dactylus, the MIS 5e succession displays a first transgressive suite of brackish to shallow-marine deposits. These latter include highly fossiliferous muds rich in C. caespitosa, overlain by a fossil-rich calcarenite, 2 m-thick, yielding warm-water “Senegalian” molluscs. Above this prominent stratigraphic marker (regionally called panchina), which is interpreted to represent a short-lived phase of sea-level stillstand or gentle fall during MIS 5e, renewed transgression took place, leading to the accumulation of middle-outer shelf muds, about 5 m thick. The maximum flooding zone is clearly identified on the basis of the turnaround from a deepening-up to a shallowing-up trend. The upper part of Fronte Section records a second fossil-rich, sublittoral calcarenite containing warm-water molluscs, which is interpreted to reflect the subsequent phase of sea-level highstand, likely correlative with the MIS 5e plateau.
Full-text · Article · Aug 2014 · Global and Planetary Change