1,721,058 research outputs found
Three-dimensional to two-dimensional cross-strata transition in the lower Pleistocene Catanzaro tidal strait transgressive succession (southern Italy)
No full textSandstone tidal cross-strata are the predominant sedimentary feature of strait-fill stratigraphic successions. However, although widely described in numerous studies, tidal strait-fill two-dimensional and three-dimensional cross-strata have rarely been reported to occur in discrete intervals which are laterally adjacent or vertically stacked, and the meaning of this stratigraphic architecture has not yet been fully investigated. Understanding of the processes responsible for changes in the internal features of modern and ancient tidal bedforms is essential in order to predict lateral and vertical heterogeneities in analogous reservoir strata. This facies-based study aims to interpret the three-dimensional to two-dimensional cross-strata transition observed in the lower Pleistocene mixed siliciclastic/bioclastic sandstone filling the Catanzaro Strait, in southern Italy, during a continuous phase of tectonically driven marine transgression. Tidal cross-strata disappear in the uppermost interval of the studied succession, where mudstone strata prevail. This stratigraphic trend is interpreted as the evidence of an important change in the tidal strait hydrodynamics due to a phase of relative sea-level rise. At the beginning of the transgression, three-dimensional tidal dunes migrated throughout the ca 3 to 4 km wide and ca 30 km long, WNW-ESE-oriented Catanzaro Strait, due to strong tidal currents amplified through the seaway and flowing in semi-diurnal phase opposition. As the intermediate phase of transgression enlarged the seaway width, the tidal current strength decreased as tidal water exchange occurred over a larger cross-sectional area. The progressive reduction of the bed shear stress modified three-dimensional tidal dunes into an extensive two-dimensional bedform field. At the end of the transgression, the further widening of the Catanzaro Strait into a ca 10 to 12 km wide marine passageway changed the tidally dominated strait into a non-tidal open shelf. The results of this research suggest the presence of a 'critical cross-sectional area' in the narrowest strait-centre zone which controls the activation and deactivation of tidal current amplification along a marine seaway
Sedimentary features of the Lower Pleistocene mixed siliciclastic- bioclastic tidal deposits of the Catanzaro Strait (Calabrian Arc, south Italy)
No full textThe Plio-Pleistocene infill of the Catanzaro Basin (central Calabria) includes a Lower Pleistocene (Calabrian), ~80 m thick interval made up of mixed (bioclastic-siliciclastic) sand-sized sediments. The Catanzaro palaeo-strait (Fig. 1) is interpreted as an E-W-elongated, narrow linear basin linked the Ionian and Tyrrhenian seas, producing a marine seaway or strait which was tidally-dominated during the Lower Pleistocene. Two main fault systems bound the basin: an ENE-WSW to WNW-ESE-trending system to the North and an E-W-trending system to the South, both showing an en-échelon-type pattern (TANSI et alii, 2007). The Plio-Pleistocene infill of the Catanzaro Basin unconformably overlies the Upper Miocene conglomerates and evaporites and, locally, the Paleozoic crystalline basement. From the bottom to the top, the Catanzaro Basin infill consists of a Pliocene unit (about 100 m thick) made up of limestone and marls, and erosively overlain by the mixed succession focus of this work. This succession is top-truncated by Quaternary terraced deposits and/or by surfaces of modern exposure (CHIARELLA, 2011).
Mixed deposits of the Catanzaro Strait consist of a series of vertically-stacked bidirectional cross strata (Fig. 2) which exhibit a sedimentary facies association typical of tidal dominated environments, including herringbones, bundles and re-activation
surfaces (e.g., LONGHITANO et alii, 2012a, b)
SEDIMENTARY FEATURES OF THE LOWER PLEISTOCENE MIXED SILICI-/BIOCLASTIC DEPOSITS IN THE FAULT-BOUNDED CATANZARO BASIN (CALABRIA, SOUTHERN ITALY).
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
The Miocene deposits of the Cirò Basin in the evolution of the peri-Ionian region, eastern Calabria
No full textThe Cirò Basin is located in the north-eastern partion of Calabria, between the Ionian Sea and the Sila slopes. In this area, basin successions of the Neogene and Quaternary age overlap the Paleozoic metamorphic basement of the Sila Unit. In particular, there are units consisting of continental clastic facies and coastal facies that are the basis of the Tortonian-Messinian transgression. An accurate geological-structural survey, combined with sedimentological and stratigraphic analysis, has allowed to define the limits of the Cirò Basin and the stratigraphic relationships between the various outcropping Miocene deposits. Five distinct litofacies have been recognized, each of which contains both lateral and vertical variations.The main tectonic structures control the architecture and evolution of main Neogene basins of the Calabrian terranes. From the Neogene to the Quaternary, the history of orogenic building was mainly controlled by the activity of NW-SE oriented faults and shear zones characterised by left-trascurrent kinematics. Deformation is well evidenced in the tectono-sedimentary evolution of the wedge-top basins as well as in the retro-arc domain
Deformed cross-stratified deposits in the Early Pleistocene tidally-dominated Catanzaro strait-fill succession, Calabrian Arc (Southern Italy): Triggering mechanisms and environmental significance
No full textThe Early-Pleistocene Catanzaro strait-fill succession consists of large-scale tidal sets, accumulated in a tectonically confined basin during a phase of rapid relative sea-level rise. It crops out mainly in the present-day Catanzaro Trough where numerous field sections supported the characterization of the vertical and lateral facies variations and the documentation of a variety of soft-sediment deformation structures, exposed throughout their vertical and lateral extents. The soft-sediment deformation structures (SSDS) are the result of liquefaction and fluidization processes that deformed cross-laminations and other primary structures into folds, fluid-escape structures, and structureless expanses. Three different groups of SSDS have been documented in the cross-stratified deposits of the Catanzaro strait. The detailed description of these soft-sediment deformation structures in a depositional context established by facies analysis enables interpretation in terms of possible trigger mechanisms. Consistent relationships between the occurrence of distinctive SSDS and specific tidally dominated facies have been established, indicating a probable autogenic origin for the soft-sediment deformations. Liquefaction and fluidization features are interpreted as the result of increases in water pore-pressure, induced by overloading. In particular, two types of overloading agents are hypothesized, which affect the lee and stoss sides of the migrating dunes in distinct events, and inducing the deformation of foreset laminae or sets of cross-strata, respectively
Introduction to the Special Issue “Socio-Natural Disasters and Vulnerability Reduction in the territorial ecosystems”
Full text linkThe awareness of the existence of natural hazards, the study of their characteristics and the most appropriate behaviour to adopt against them are a realistic way of manage them and reducing their negative effects on the population, cultural and artistic heritage, and social and economic activity of a given area
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