1,720,976 research outputs found
A revision of the Triassic sequence stratigraphic framework of the Dolomites (Italy). The impact of climate, volcanics, tectonic and changes in the carbonate factories
No full textFacies and geometries of carbonate platforms of the Dolomites after the Carnian Pluvial Event (CPE).
No full textThe depositional architecture of Latemar and Sella, isolated Triassic microbial platforms of the Dolomites, NE Italy
No full textMicrobial carbonate platforms are common in the Pre-Cambrian and most of the Phanerozoic, often hosting hydrocarbons, but since they are distinct from modern coral reefs or skeletal carbonate ramps, a standardised facies model for such microbial-dominated carbonate bodies is still missing. The reconstruction of the stratigraphic architecture of these types of depositional systems must often rely on investigation of outcrop analogues. The authors propose herein a 2 day field itinerary in which depositional features, depositional geometries and facies architecture of two Triassic microbial carbonate platforms of the Dolomites (Southern Alps, NE Italy) will be presented at key outcrops and discussed. The Dolomites host a variety of Triassic carbonate platforms of this type. They are characterised by high relief and steep slopes and have been studied as analogues to Palaeozoic and Mesozoic hydrocarbon reservoirs such as those of Central Asia, Central America, northern Russia or North America, with which they share significant similarities. In this guide, two excursions are described and focus on the upper Anisian (Middle Triassic) Latemar and the lower Carnian (Upper Triassic) Sella; two examples that are particularly suitable for directly appreciating and understanding architecture and facies characteristics of such microbial sedimentary units because of their limited size
and excellent exposure. Easy accessibility makes it possible to examine several key features through a short visit, with only minor safety issues. The Latemar platform has escaped pervasive dolomitization, so that sedimentary facies are very well preserved. Furthermore, the Sella and the Latemar crop out perfectly, exposing the depositional geometries and their lateral facies relationships with coeval deep-water basins at seismic-scale. The proposed field itinerary is aimed at geologists, either from industry or from academia, who have interest in microbial carbonate platforms, wish to learn sequence stratigraphy in the field and to look at outcrop analogues of carbonate depositional systems as seen in seismic surveys
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
Three-dimensional modeling of dramatic changes in depositional geometries of the late Triassic carbonate platforms of the Southern Alps (Italy).
No full textCyclostratigraphic investigations in the Calcare Massiccio (Early Jurassic, Umbria-Marche Basin) through photogrammetry
No full textIn this paper, we present a case study to demonstrate the potential of photogrammetry in cyclostratigraphic applications. To this end, we considered an ~300-m-thick section exposing the Lower Jurassic Calcare Massiccio Formation in the Marche Apennines of central Italy. The Calcare Massiccio comprises a thick succession of peritidal shallow-water carbonates displaying a prominent sedimentary cyclicity, where supratidal and subtidal facies alternate. The section investigated in this study is exposed on the wall of an active quarry and is almost completely inaccessible because it is vertical and because of safety and liability regulations. This setting prevents the application of standard sampling and facies analysis techniques on the whole series. An accurate three-dimensional model of the quarry wall was therefore produced by processing ~360 digital images through photogrammetry and generating a high-resolution (centimeter-scale) point cloud of the outcrop with red-green-blue (RGB) values associated with each point. An ~150-m-long log representing color variations on a continuous portion of the exposed succession was then extracted from the point cloud by converting the original RGB values to grayscale values. The main facies were directly investigated in an ~10-m-long accessible section that was logged and sampled, and it was established that supratidal facies with planar stromatolites and teepee structures are darker in color, while subtidal facies, made of bioturbated mudstones to floatstones with gastropods and oncoids, display lighter color. This provided ground-truth data with which to interpret the grayscale variations in terms of facies alternations. Time-series analysis was then carried out on the grayscale series, and this revealed prominent cyclicities. Because the biochronostratigraphic framework of the Calcare Massiccio is poor, the potential orbital origin of these frequencies was tested with the average spectral misfit technique. Preliminary results suggest that the observed spectral features are compatible with Milankovitch periods and that astronomical forcing might have been a major driver in the deposition of the Calcare Massiccio Formation. Furthermore, they testify to the great potential of photogrammetry in cyclostratigraphic applications, especially when large-scale, inaccessible outcrops have to be investigated
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
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