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The transition from alkaline to tholeiitic magmas: a case study from the Orosei-Dorgali Pliocene volcanic district (NE Sardinia, Italy)
No full textDuring the Pliocene, simultaneously with the opening of the Tyrrhenian Sea, mafic magmas were erupted in NE Sardinia (Orosei-Dorgali area). These range from mildly alkaline with sodic affinity (about 80% of exposure) to tholeiitic (about 20%). The tholeiitic rocks (basaltic andesite) are slightly more evolved than the alkaline ones and show geochemical features (e.g., Mg# 20). Similar incompatible element ratios for both alkaline and tholeiitic rocks suggest different degrees of melting of a single mantle source. Mathematical modeling indicates similar to 4-6% and similar to 10-15% partial melting for alkaline and tholeiitic lavas, respectively. Trace element abundances of the Orosei-Dorgali volcanic rocks are typical of Plio-Pleistocene volcanic rocks of Sardinia but differ strongly from other Cenozoic anorogenic volcanic rocks of Europe. Similarly, Sr (Sr-87/Sr-86=0.70442-0.70455), Nd (Nd-143/Nd-144=0.512465-0.512558) and Ph (Pb-206/Pb-204=17.74-17.86; Pb-207/Pb-204=15.53-15.60; Pb-208/Pb-204=37.89-38.02) isotopic ratios are very unusual when compared with other Cenozoic European volcanic rocks. Trace element abundances and isotopic composition of the Orosei-Dorgali volcanic rocks suggest a lithospheric mantle origin. (C) 2002 Elsevier Science B.V. All rights reserved
The role of metasomatising fluids in the genesis of orogenic magmas. A case study from Sardinia, Italy
No full textThe Pliocene Montiferro, volcanic complex (central-western Sardinia, Italy): geochemical observations and petrological implications
No full textThe Montiferro volcanic complex is one of the several districts of Middle Miocene-Quaternary magmatism of Sardinia. It was active between 3.9 and 1.6 Ma, with a climax at 3.6 Ma. Erupted rocks have a wide spectrum of compositions, ranging from basic and ultrabasic to highly evolved lithotypes, belonging to three different magmatic suites: 1) strongly alkaline sodic series; 2) mildly alkaline sodic series; 3) tholeiitic series. The products of the strongly alkaline series are mainly basanites, erupted both at the first and at the last stages of Montiferro activity. Strongly alkaline magmas are likely to have risen rapidly to the surface, as testified by the common occurrence of mantle xenoliths and by the absence of differentiated products. The mildly alkaline series ranges from hawaiites to trachytes and phonolites through very abundant mugearites and few benmoreites. Primitive magmas of this series are likely to have ponded at crustal levels, experiencing both differentiation and crustal contamination processes. Finally, the tholeiitic series is mainly represented by rare basaltic andesites and a few basaltic trachyandesites straddling the alkaline/subalkaline boundary. Incompatible trace elements, 87Sr/86Sr and 143Nd/144Nd isotopic ratios are consistent with the derivation of these products from a common mantle source, represented by a spinel-lherzolite. Primitive magmas of three magmatic suites may have generated by different degrees of partial melting of this source, progressively increasing from strongly alkaline (~1-3% partial melting) to mildly alkaline (~5-7%) and tholeiitic products (~10-12%). Geochemical modellings suggest that this source is represented by a DMM-like lithospheric mantle, metasomatised by small inputs of various crustal components
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
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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