1,720,967 research outputs found
Field relations, geochemistry and geodynamic implications of chromitites from the Bandan Mine, Eastern Iran
No full textThe Bandan chromite mine is the main chromite deposit in Sistan suture zone, eastern Iran. The chromite deposits are structurally tabular to lens-shaped bodies hosted by dunitic to harzburgitic mantle peridotites. Similar to Alpine type podiform chromites, chromitite pods are enclosed within dunitic envelops. The chromites show mainly massive to disseminated and also brecciated textures. Chemically, the Cr/Fe ratio is higher than 2 and TiO2 content in accordance with ophiolitic chromites is low (< 0.2 wt. %). As a result of low Cr# (Cr# = Cr x 100 / (Cr + Al)) ranging from 50 to 52 the Bandan chromite deposit is high-Al type. Calculated parental melt chemistry shows MORB (Mid-ocean ridge basalt)-type signature with Al2O3 and FeO/MgO ratio contents of 15-16 and 1.1-1.2, respectively. Although the geodynamic setting of high-Al podiform chromites have been debated but petrographical - geochemical characteristics of ophiolitic mantle-crust sequences may relate chromite genesis to supra-subduction zone setting
Petrology and tectono-magmatic significance of the Nehbandan ophiolite (Sistan Suture Zone, E. Iran): Implication for the evolution of the Iranian Neo-Tethys.
No full textPetrological and geochemical constraints on the origin of the Nehbandan ophiolitic complex (eastern Iran): Implication for the evolution of the Sistan Ocean
No full textThe Nehbandan ophiolite complex (NOC) crops out in the Sistan suture zone, which marks the boundary between the Lut and Afghan continental blocks. The NOC is composed of various ophiolitic lithotypes included in a tectono-sedimentary mélange, which are commonly interpreted as remnants of the oceanic lithosphere of the Sistan Ocean. Three different sequences (or associations) of ophiolitic rocks can be recognized in the NOC: (1) mantle peridotites consisting of clinopyroxene- (cpx-) rich harzburgites and depleted harzburgites; (2) olivine websterite–pyroxenite–gabbronorite sequence; (3) wehrlite–troctolite–cumulate gabbro–isotropic gabbro–basalt sequence. Petrographic observations, mineral chemistry, whole- rock chemistry, and rare earth element (REE) modelling carried out on the different rock associations led to the following conclusions: (1) the wehrlite–troctolite–cumulate gabbro–isotropic gabbro–basalt association represents a portion of oceanic crust generated in a mid-ocean ridge setting; (2) the cpx-rich harzburgites represent the residual mantle after 5–20% removal of mid-ocean ridge basalt-type (MORB) melt. This residual mantle was subsequently enriched in light REE (LREE) by subduction-derived fluids in a supra-subduction zone (SSZ) setting and it compositionally represents the typical mantle source for boninitic melts; (3) the olivine websterite–pyroxenite–gabbronorite association represents a portion of oceanic crust generated in an intra-oceanic arc setting; (4) the depleted harzburgites represent the residual mantle after 10–30% removal of boninitic melts in an intra-oceanic arc setting. The data presented in this paper provide new constraints for the tectonic evolution of the Iranian sector of the Neo-Tethys. In fact, in contrast with previous geodynamic models, the occurrence of SSZ ophiolites in the NOC implies that the phase of convergence between the Lut and Afghan blocks, which led to the closure of the Sistan Ocean, was accompanied by the development of an intra-oceanic arc setting
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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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