1,721,002 research outputs found
Development of an intraoceanic large igneous province: the Kerguelen Plateau and Broken Ridge, southern Indian Ocean
No full textOrigin and evolution of the Kerguelen Plateau, Broken Ridge, and Kerguelen Archipelago: editorial
No full textProceedings of the Ocean Drilling Program, Scientific Results. Vol. 183. Kerguelen Plateau-Broken Ridge: a large Igneous province: covering Leg 183 DV "Joides Resolution", Fremantle, Australia, to Fremantle, Australia, Sites 1135-1142, 7 Dec 1998-11 Feb 1999
No full text
Leg 183 synthesis: Kerguelen Plateau-Broken Ridge – a large igneous province
No full textThe Kerguelen Plateau and Broken Ridge form a large igneous province (LIP) in the southern Indian Ocean. The main objectives of Ocean Drilling Program Leg 183 were to understand the origin and evolution of this LIP and the impact of its formation on the environment. Igneous basement (33 to 233 m of penetration) has been recovered from 11 drill sites on the LIP, and 7 are Leg 183 sites. Studies of the basement and sediment cores lead to the following conclusions. 1. Formation of the LIP postdated breakup between India and Antarctica, with eruption ages (40Ar/39Ar) ranging from ∼119 Ma in the southern Kerguelen Plateau (SKP) to ∼34 Ma in the northern Kerguelen Plateau. Apparently, peaks in magmatic output (∼0.9 km3/yr) occurred in the intervals of 119-110 and 105-95 Ma. Although an important caveat is that we have access only to uppermost basement of a thick (∼20 km igneous crust, these results are inconsistent with massive volcanism associated with a single plume head and continental breakup. 2. The uppermost igneous basement is dominantly tholeiitic basalt. Based on the physical characteristics of the lava flows, which indicate subaerial eruption, and the occurrence of overlying terrestrially derived sediments containing wood fragments, fern remains, and terrestrial palynoflora, much of the LIP was above sea level when magmatic output was high. 3. The geochemical characteristics of basalt forming the LIP are unlike mid-ocean-ridge basalt (MORB). There are, however, significant geochemical differences between tholeiitic basalt erupted at each site. These differences are attributed to varying proportions of components derived from the Kerguelen plume, depleted MORB-related asthenosphere, and continental lithosphere. 4. Based on radiogenic isotopic ratios and incompatible element abundances, tholeiitic basalt of Cretaceous age from spatially diverse locations (Site 738 in the SKP, Site 1137 on Elan Bank, Site 747 in the Central Kerguelen Plateau (CKP), and Site 1142 on Broken Ridge) contains up to ∼5% of a component derived from continental crust. The Proterozoic-age zircon and monazite in clasts of garnet-biotite gneiss in a conglomerate intercalated with basalt at Site 1137 demonstrate that continental crust fragments are present in the Indian Ocean lithosphere. 5. Surprising new results for oceanic LIPs are the dominance of alkalic lavas, trachybasalt to trachyte and rhyolite, at Skiff Bank and the pyroclastic deposits present on Skiff Bank, Elan Bank, and the CKP. Explosive subaerial volcanism at high latitudes can contribute volatiles to the stratosphere; therefore, LIP volcanism may have had a significant environmental impact. 6. Flora and fauna preserved in Kerguelen Plateau sediments provide a long-term record of the plateau's environment, beginning with terrestrial and shallow-marine deposition followed by equable Cretaceous paleoceanographic conditions, the abrupt Cretaceous/Tertiary boundary, the Late Paleocene Thermal Maximum, and cooling of the Southern Ocean through Tertiary time.SCOPUS: ar.jinfo:eu-repo/semantics/publishe
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
- …
