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The channel-levée transition: insights from the Tachrift Turbidite System (Complex T6, Taza-Guercif Basin, NE Morocco)
Full text linkTurbidite channel-levée complexes have been the focus of research over more than forty years. Although high-resolution 3D seismic yielded detailed imaging of these deposits, facies transition from channel to correlative levée remains elusive. To fill this gap, extensive and well-exposed outcrops are important, as they provide information on fine-scale facies heterogeneity. Despite this, documented outcrops where accordant channel fills and overbank sediments can be observed with continuity are relatively few/small. We present the Tachrift Project aimed at the field-based reconstruction of the Tachrift Turbidite System (Tortonian-Early Messinian) in the Taza-Guercif Basin (Rifian Corridor, NE Morocco). Among the 9 superimposed, spectacularly exposed channel-levée complexes (T1 to T9) filling the basin for a total 600 m thickness, here we focus on the T6 complex. Detailed geological mapping was integrated with measurements and facies analysis on 46 logs, and physical stratigraphic correlations. T6 (12 m thick) is bounded above and below by 3 to 10 m-thick mudstone units. It consists of three stacked sandstone-rich units that are separated by erosional surfaces. Each unit comprises peculiar, physically traced facies associations showing different channel-levée transitions. They reveal an eastward channel belt migration and a progressive flow energy/density increase. Benefitting from 3D great exposures, the ongoing project provides i) characterization and correlation of channels and accordant overbank sediments, ii) insights on evolution of a channel-levée complex from inception to its deactivation, iii) sub-seismic scale lithological and architectural calibration for analogue subsurface deposits
How hyperpycnal deposits and surge-like turbidites coexist? An example from the Oligocene Monastero FM. (Tertiary piedmont basin, NW Italy)
No full textNumerical taxonomy applied to Upper Triassic Megalodontidae: first attempts on the genera Neomegalodon and Triadomegalodon
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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
Lithostratigraphy and facies architecture of a Lower Permian continental succession in Central Southern Alps (Orobic Basin, Italy)
Full text linkThe Lower Permian Pizzo del Diavolo Fm. of the Orobic Alps (Laghi Gemelli Gr., upper Collio Fm. Auct.) records, along an E-W area more than 50 km long, events that occurred in a complex continental depositional system, during semi-arid climatic condiitons and in a transtensional tectonic setting. This formation postdates intense volcanic activity and overlays parts of a large caldera and its vast surrounding areas, covered by dominating pyroclastic deposits interbedded with rare braid-plain and lacustrine sediments (Cabianca Volcanite). Post-volcanic sediment distribution reflects the existence of connected half-grabens, characterised by transverse sedimentary input (coarse-grained alluvial fans) evolving into fine-grained heterolitic deposits in the depocentre, hosting ephemeral playa-lakes.
Field mapping of two marginal sectors of the Orobic Basin (Pizzo dei Tre Signori massif and Lake Barbellino area), coupled with facies analysis of the Pizzo del Diavolo Fm., led to the identification of significantly different sedimentary evolutions. At the eastern and western ends of the basin, the Pizzo del Diavolo Fm. consists of alluvial fan and floodplain facies associations that differ from the previously studied stratigraphic architecture described in the central part of the basin. The southern borders of the studied areas are characterised by coarse-grained, fining-upward alluvial fan deposits (Val Sanguigno Conglomerate) at their base. The petrographic composition of the conglomerates from the northern border of the basin (Ponteranica Conglomerate) indicates differences in the exposed and eroded rocks from the northern and southern highs, with changes along the basin borders, where conglomeratic units with dominating basement clasts (Mt. Aga Conglomerate) occur. Floodplain facies are similar all along the basin, even if with thickness changes (up to 700 metres in the western part).
The stratigraphic architecture observed in the eastern and western sectors markedly differs from that described in the central part of the basin (where a well-organised succession of two fining-upward cycles is described), preventing a detailed correlation of the events across the basin. Also the relative abundance of facies in these three sectors of the basin is different: fine-grained sediments dominate in the central part, whereas coarser deposits occur to the west (Pizzo dei Tre Signori massif) and to the east (Lake Barbellino). The complex architecture of the basin, the difficulty in recognising events or trends that can be traced all across the basin and the different petrographic composition of conglomerates along the northern and southern margins of the basin suggest not only that tectonics controlled facies distribution and depositional environments but also the existence of sub-basins characterised by different evolutions within the greater Orobic Basin, further supporting the envisaged role of strike-slip tectonics
The Tachrift channel-levée turbidite systems (Tortonian) of the Taza-Guercif Basin (South Rifian Corridor, NE Morocco)
No full textTectonics and sedimentation interplay in the eastern Tertiary Piedmont Basin (ArquataScrivia, NW Italy): insights from new seismo-stratigraphic analysis
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