1,720,963 research outputs found
Emplacement and rejuvenation of a granitic batholith: the Valle Mosso plutob (Sesia Magmatic System)
No full textThe Lower Permian Valle Mosso pluton (VMP) is a granitic body intruded at upper crustal levels in the rocks of the pre-Alpine basement of the Ivrea-Verbano and Serie dei Laghi units, respectively. The VMP has been recognized as an integral part of a magmatic system termed Sesia magmatic System (Quick et al., 2009), which during the Lower Permian developed through the continental crust up to the surface and caused explosive rhyolitic volcanism that eventually led to the formation of a > 15 km diameter rhyolitic caldera. Fieldwork helped in constraining the VMP internal geometry, with the distinction of several laccolithshaped intrusive units noticeable for their modal abundances and textural features. Equigranular coarsegrained granite constitutes the bulk of the intrusion, together with subordinate volumes of porphyric granite and numerous small fine-grained two-micas intrusive bodies. A small body (roughly 0.5 by 1 km) of porphyry occurs within the porphyric granite and presents irregular to gradational contacts to its host rock. Major and trace-element and isotopic composition of this porphyry is equal to that of the surrounding granite. However, porphyry matrix and phenocrysts present microtextural features that indicate resorption and undercooling. These features (sieve textures of plagioclase, quartz and biotite resorption) paired with indications from Ti-in- Qz geothermometer on porphyry samples (Wark & Watson, 2006) are descriptive of temperature fluctuations within a crystal mush. Field evidence indicate that the Valle Mosso pluton experienced numerous episodes of mafic melt injections during different stages of its incremental growth. These mafic melts produced significant effects on the thermal budget of the granitic intrusion, rejuvenating and possibly mobilizing batches of the VMP. Based on similar whole-rock composition and reabsorption texture observed in coeval granite porphyry and volcanic products of the Sesia Caldera, a possible link between rejuvenated granitic melts and eruptive products has been postulated. The VMP may provide an insight into the storage and remobilization process that drive the eruption of large amount of melts in caldera-forming volcanic systems
Hybrid granitic magma originated at the advancing front of basaltic underplating: inferences from the Sesia Magmatic System (Wesyern Alps)
No full textMost rhyolitic and granitic rocks of the large Permo-Carboniferous province of Europe show a restricted range in isotopic compositions, intermediate between mantle and crustal values. We propose an explanationto the relative homogeneity of these hybrid granitic magmas based on geochemistry and field observationsof the Sesia Magmatic System, which includes a deep crustal gabbroic complex, upper crustal granite plutons and a volcanic field dominated by rhyolitic caldera fill tuff (Quick et al., 2009). Isotopic compositionsof the deep crustal gabbro overlap those of coeval andesitic basalts, whereas coeval granites define adistinct, more radiogenic cluster (Sri ≈ 0.708 and 0.710, respectively). AFC computations starting from thebest mafic candidate for a starting melt show that isotopic compositions and trace elements of andesitic
basalts may be modelled by assimilation of about 30% of partially depleted crust and about 15-29% fractionation. Trace elements of the deep crustal gabbro cumulates require a further ≈ 60% fractionation of the andesitic basalt and loss of about 40% of silica-rich residual melt (Sinigoi et al., 2016). The compositionof the granite pluton is consistent with a mixture of almost equal parts of residual melt delivered from the gabbro and the anatectic melt. Chemical and field evidence lead to infer a conceptual model which links the production of the two granitic components to the evolution of the gabbroic complex. During the growth of the gabbroic complex, progressive incorporation of packages of crustal rocks resulted in a roughly steady-state rate of assimilation. Upwards segregation of anatectic melts delivered from the hot zone above the
advancing mafic intrusion facilitates reactive bulk assimilation of the restite by density-driven stoping. At each cycle of mafic intrusion and incorporation of roof layers, residual and anatectic melts are produced in more or less constant proportions, because the amount of anatectic melt produced at the provisional roof is a function of volume and latent heat of crystallization of the intruded mafic melt which in turn produces proportional amounts of hybrid gabbro cumulates and residual melt. Such a process can explain the restricted range in isotopic compositions of most rhyolitic and granitic rocks of the Permo-Carboniferous province of Europe and elsewhere
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
Structural characterization and K-Ar illite dating of reactivated, complex and heterogeneous fault zones. Lessons from the Zuccale Fault, Northern Apennines
Full text linkWe studied the Zuccale Fault (ZF) on Elba, part of the Northern Apennines, to unravel the complex deformation history that is responsible for the remarkable architectural complexity of the fault. The ZF is characterized by a patchwork of at least six distinct, now tightly juxtaposed brittle structural facies (BSF), i.e. volumes of deformed rock characterized by a given fault rock type, texture, colour, composition, and age of formation. ZF fault rocks vary from massive cataclasite to foliated ultracataclasite, from clay-rich gouge to highly sheared talc phyllonite. Understanding the current spatial juxtaposition of these BSFs
requires tight constraints on their age of formation during the ZF lifespan to integrate current fault geometries and characteristics over the time dimension of faulting. We present new K–Ar gouge dates obtained from three samples from two different BSFs. Two top-to-the-east foliated gouge and talc phyllonite samples document faulting in the Aquitanian (ca. 22 Ma), constraining east-vergent shearing along the ZF already in the earliest Miocene. A third sample constrains later faulting along the exclusively brittle, flat-lying principal slip surface t
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