1,720,955 research outputs found
Facies Architecture and Evolution of a Cretaceous, Tectonically-Controlled, Carbonate Slope from Western Sicily (Italy)
No full textThe stratigraphic architecture of a Cretaceous carbonate slope from north western Sicily (Italy) has been reconstructed on the basis of detailed field sections. The wire cut walls of a number of quarries that extract the Cretaceous limestones as ornamental stones allowed the mapping of the stratal architecture and lithologies at various scales.
The vertical and lateral facies relationships in this about 1000 m thick depositional system account for a complex sedimentary dynamics along a carbonate platform escarpment that was strongly influenced by syn-sedimentary transtensional tectonics associated to magmatism. Although the original relationships with the carbonate platform were obscured by the Maghrebian orogeny, the source area of the clastic carbonates can be envisaged in the Panormide Platform, a paleogeographic unit Late Triassic to Eocene in age that crops out in northern Sicily.
The most common facies along the Cretaceous slope are mass transport deposits (MTD) with large (decimetre to metre-scale) elements of rudist limestone in a matrix of skeletal rudstone. They alternate to finer grained gravity flow deposits. Thin intercalations of Scaglia-type calcilutites (background sediments) point to occasional interruptions of the gravity flows.
The onset of the slope sedimentation occured in the Berriasian, as documented by the abrupt overlap of MTD with ellipsactinids/corals extraclasts on calpionellid wackestone. This event points to the conversion of a gentle ramp into a faulted escarpment that has favourded the collapse of the ellipsactinid-bearing extraclasts.
Two subsequent episodes of dissection of the slope are indicated by pillow basalt intercalations. Based on the benthic communities in the overlapping sediments the lava emissions could be constrained to the Aptian and Albian.
As recorded in many others carbonate platform-basin systems, the Cenomanian records a maximun downslope shedding of skeletal debris transported by turbidites and grain flows. A progressive decrease of the clastic supply along slope is recorded from Senonian onward as a consequence of the gradual drowning of the adjacent platform. However, the resedimentation pulses lasted at least up to the Maastrichtian thus indicating the perduration of a shallow water carbonate production in small isolated patches.
The study provides new insights for the understanding of the sedimentary dynamics along Cretaceous escarpments from western Tethys controlled by crustal extensional deformations
A Cretaceous carbonate escarpment from Western Sicily (Italy): biostratigraphy and tectono-sedimentary evolution
No full textThe presence of a huge carbonate slope of Cretaceous age is recorded in some imbricated thrust sheets from the Maghrebian fold-and-thrust belt cropping out in northwesternmost Sicily (southern Italy). The sedimentological features of this escarpment, named as the Western Sicily Cretaceous Escarpment (WSCE), have been recently described. The present paper aims to provide a detailed bio- chronostratigraphic characterization of the different facies types that occur in the four lithostrati- graphic units spanning the whole slope depositional system. The detailed biostratigraphic analysis and correlation of a number of well-exposed sections allowed to differentiate eight informal biozones and to place the different studied sections, either from a single tectonic unit or from different ones, in a reliable chronostratigraphic frame. The integration of sedimentological and biostratigraphic data allowed in turn to time-constrain the main tectono-sedimentary events along the WSCE. In particular: i) the abrupt transformation from a carbonate ramp to a tectonically-controlled escarpment during the Berriasian- Valanginian; ii) the peak of tectonic instability leading to the emplacement of thick megabreccia bodies and repeated submarine volcanic emissions during the Aptian- Cenomanian; iii) the almost coeval increase in the skeletal supply in response to highstand shedding occurred during the Albian- Cenomanian; iv) the tectonic backstepping of the carbonate depositional system during the Senonian ending with the definitive shutdown of the carbonate factory in the late Maastrichtian. The acquired biostratigraphic dataset is in large part new for the Cretaceous of Sicily and provides information on the associations that populated a southwestern Tethyan carbonate platform during the Cretaceous
Carbonate slope re-sedimentation in a tectonically-active setting (Western Sicily Cretaceous Escarpment, Italy)
No full textTectonic processes are widely considered as a mechanism causing carbonate platform margin instabilities leading to the emplacement of mass transport deposits and calciturbidites. However, only few examples establishing a clear link between tectonics and re-sedimentation processes are known from the lit- erature. The two-dimensional and three-dimensional wire-cut walls of hun- dreds of quarries extracting ornamental limestones (for example, Perlato di Sicilia) from the Western Sicily Cretaceous Escarpment in Italy expose a series of mass transport deposits. The depositional architecture, spatial facies distri- bution and sedimentary features of these deposits were studied in detail. Thin section analysis was used to define the microfacies characteristics and to determine the age of the re-sedimented limestones. Eleven facies types grouped into four facies associations were recognized that defined specific depositional processes and environments. The stratigraphic architecture of the slope was reconstructed using four composite facies successions based on the detailed analysis and correlation of the field sections. The palaeoslope orienta- tion was reconstructed based on the analysis of synsedimentary faults, slump scars and pinch-out geometries. The Western Sicily Cretaceous Escarpment was strongly influenced by synsedimentary transtensional tectonics in combi- nation with magmatic processes, as suggested by the presence of tuffites and pillow lava intercalations within the re-sedimented carbonate series. These volcanics point to a major role of crustal shear as a trigger for mass transport deposit emplacement. The facies distribution along the Western Sicily Creta- ceous Escarpment delivers new insights into the deformation processes accompanying the crustal extension of the Cretaceous western Tethys realm
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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