1,721,004 research outputs found
The controlling factors of an Upper Oligocene carbonate ramp (Attard Member, Lower Coralline Limestone Formation, Malta): from facies to paleolatitude
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Facies analysis and paleoenvironmental interpretation of the Late Oligocene Attard Member (Lower Coralline Limestone Formation), Malta
No full textThe Oligocene represents a key interval during which coralline algae became dominant on carbonate ramps and luxuriant coral reefs emerged on a global scale. So far, few studies have considered the impact that these early reefs had on ramp development. Consequently, this study aimed at presenting a highresolution analysis of the Attard Member of the Lower Coralline Limestone Formation (Late Oligocene, Malta) in order to decipher the internal and external factorscontrolling the architecture of a typicalLate Oligocene platform.Excellent exposures of the Lower Coralline Limestone Formation occurring along continuous outcrops adjacent to the Victoria Lines Fault reveal in detail the three-dimensional distribution of the reef-associated facies. A total of four sedimentary facies have been recognized and are grouped into two depositional environments that correspond to the inner andmiddle carbonate ramp.Theinner ramp was characterized by a very high-energy, shallow-water setting, influenced by tide and wave processes. This setting passed downslope into an inner-ramp depositional environment which was colonized by seagrass and interfingered with adjacent areas containing scattered corals. The middle ramp lithofacies were deposited in the oligophotic zone, the sediments being generated from combined in situ production and sediments swept from the shallower inner ramp by currents. Compositional characteristics and facies distributions of the Attard ramp are more similar to the Miocene ramps than to those of the Eocene. An important factor controlling this similarity may be the expansion of the seagrass colonization within the euphotic zone. This expansion may have commenced in the Late Oligocene and was associated with a concomitant reduction in the aerial extent of the larger benthonic foraminifera facies. Stackingpattern analysis shows that the depositional units (parasequences) at the study section are arranged into transgressive–regressive facies cycles. This cyclicity is superimposed on the overall regressive phase recorded by the Attard succession. Furthermore, a minor highstand (correlated with the Ru4/Ch1 sequence) and subsequent minor lowstand (Ch2 sequence) have been recognized. The biota assemblages of the Attard Member suggest that carbonate sedimentation took place in subtropical waters and oligotrophic to slightly mesotrophic conditions. The apparent low capacity of corals to form wave-resistant reef structures is considered to have been a significant factor affecting substrate stability at this time. The resulting lack of resistant mid-ramp reef frameworks left this zone exposed to wave and storm activity, thereby encouraging the widespread development of coralline algal associations dominated by rhodolith
Pedley M. S. The Commerce of Cartography: Making and marketing maps in 18 th-century France and England
No full textClout Hugh. Pedley M. S. The Commerce of Cartography: Making and marketing maps in 18 th-century France and England . In: Annales de Géographie, t. 115, n°649, 2006. Wilderness. La nature en amérique du nord, sous la direction de Paul Arnould et Éric Glon. pp. 331-332
Pedley M. S. The Commerce of Cartography: Making and marketing maps in 18 th-century France and England
No full textClout Hugh. Pedley M. S. The Commerce of Cartography: Making and marketing maps in 18 th-century France and England . In: Annales de Géographie, t. 115, n°649, 2006. Wilderness. La nature en amérique du nord, sous la direction de Paul Arnould et Éric Glon. pp. 331-332
Cool-Water Carbonate Ramps: A review.
No full textMarine, cool-water carbonate ramps considered in terms of their defining features. Cool-water carbonate environments are dominated by open, skeletal debris-covered sea bottoms which support biological assemblages devoid of hermatypic corals, calcified green algae and non-skeletal grains. The growing body of modern literature deals mainly with Neogene to Recent examples, particularly from the Australia, New Zealand and Mediterranean regions. Nevertheless, many ancient examples have be recognised and without doubt many more, currently described as ‘tropical carbonates’, will also be found to be cool-water examples. It is now becoming clear that a distinction must be made between those deposits associated with macrotidal regimes (i.e. World ocean sites) and those associated with land locked water bodies such as the Mediterranean Sea. The principle difference between the two is not so much the diversity of biota but, more importantly, the minimal fair-weather reworking processes which characterise microtidal seas. This commonly allows colonisation and sediment preservation in the inner ramp zone. Biozones occupy much deeper water sites on open ocean ramps, particularly where ramps are storm-dominated. The correspondingly wider inner ramps in these World ocean sites generally become dominated by mass bioclastic reworking
The Monte Carrubba Formation (Messinian, Sicily) and its correlatives: new light on basin-wide processes controlling sediment and biota distributions during the Palaeomediterranean-Mediterranean transition.
No full textA little known marine Miocene (Messinian) succession in the Hyblean region of south eastern Sicily preserves a carbonate ramp sequence which developed on the tectonically stable foreland margins of the African Plate (Pelagian Block). The ramp (Monte
Carrubba Formation) was distally steepened and contained a shoalwater barrier and lagoonal inner ramp complex. The outer ramp
is poorly preserved though distal deep water ramp facies (Tellaro Formation) in the south Hyblean region preserve a full
Globorotalia mediterranea Subzone and major part of the Globigerina multiloba Subzone succession. This ramp sequence
faithfully records the subtle interplay between the global eustatic curve and internal Palaeomediterranean base-level signatures for the Late Miocene. The earliest second order Palaeomediterranean lowstand occurred in the Late Tortonian at about 7.3 Ma and a second occurred at about 6.75 Ma within the Early Messinian G. mediterranea Subzone. Although the overriding control at the time was the global eustatic curve, harmonic discrepencies between it and the Palaeomediterranean curve resulted from constriction of the Atlantic connection during the latest Tortonian. From about 6.4 Ma until about 5.96 Ma increasingly restricted conditions developed across the Monte Carrubba inner ramp. These faithfully reflect many second order, constriction-driven Palaeomediterranean sea-level oscillations which were superimposed on to the falling global signal as the connecting Atlantic seaways became constricted. These oscillations resulted in major reductions in planktonic faunal diversity within the outer ramp, followed by total emergence of the inner ramp by about 6.05 Ma. Marine deposition continued until about 5.96 Ma in the southern part of the Hyblean region. However, between 6.05 Ma and about 5.6 Ma the amplitude of successive Palaeomediterranean sealevel
oscillations increased to over 100 m, causing prolonged periods of total Palaeomediterranean isolation. The Hyblean
carbonate suite also contains post-Messinian Salinity Crisis (post-MSC) ‘Lago Mare’ highstand deposits which are developed
unconformably above the Monte Carrubba Formation. The widespread distribution of hyposaline to near-marine Congeria faunas within the Lago Mare episode argues for high post-MSC Mediterranean water levels in the Central Mediterranean Late Messinian
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
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