1,720,989 research outputs found
PLAGIOCLASE FABRIC DEVELOPMENT IN THE MORIN SHEAR ZONE, QUEBEC, CANADA
No full textLower crustal rheology plays an important role in plate-scale tectonic processes.
Understanding the deformation behavior of feldspar is critical because it is a volumetrically important mineral in the lower crust. I report field-based and microstructural work from the Morin anorthosite of Quebec, Canada, where it is deformed by the Morin shear zone (MSZ). The 20 km wide MSZ deformed at granulite facies conditions; approximately 10 km of the MSZ overlaps with the eastern portion of the Morin anorthosite. The foliation generally dips gently to
moderately to the west, though in some areas it dips east. Lineation is consistently strike-parallel (~NS and horizontal). MSZ tectonites record a gradient in fabric development, in which the protolith is overprinted by weakly to strongly developed deformational fabrics. Fabrics observed within the MSZ are labeled as: Protolith fabrics; Type 1; Type 2; and Type 3 fabrics, with fabric development increasing from protolith to type 3. Microstructures across this gradient record dynamic recrystallization of feldspar by subgrain rotation in the type 1 fabrics and bulge nucleation in the type 3 fabrics. Type 3 fabrics are found throughout the MSZ, whereas regions containing type 1 and 2 fabrics are typically located on the north-central side of the MSZ. The fabric gradient generally correlates with a change in deformation temperatures recorded by Ti-in- quartz thermobarometry. Analyses indicate that the protolith fabrics record the highest temperatures (~720o C) and type 3 fabrics record the lowest temperatures (~630o C). Electron backscattered diffraction analysis of anorthite demonstrate fabric intensity is associated with grain size reduction, increased shape preferred orientation, and changes in crystallographic preferred orientation patterns. Dynamically recrystallized grain sizes range from 65 to 359 microns, corresponding to piezometric differential stresses of approximately 51 (type 3) and 16 MPa (protolith fabrics), respectively.
The Morin shear zone records top-to-the-N kinematics resulting from deformation below an “orogenic lid” of the Grenville orogeny. The variable fabric development is interpreted to records a system of anastomosing high strain zones surrounding lower strain blocks. This system is inferred to have formed as the Morin shear zone progressively localized from a wide shear zone at higher temperatures into an anastomosing shear zone at lower temperatures
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
The Structural and Petrologic Evolution of the Red Hills Ultramafic Massif: Coupled Melt Migration and Deformation during Subduction Initiation
Full text linkThe Red Hills ultramafic massif, located on the South Island of New Zealand, contains a three-stage history of overprinting deformation which occurred during the onset of Permian subduction along the Australian-New Zealand portion of the Gondwanan margin. Geologic mapping of the massif delineates four compositional units which are, from east to west: Massive harzburgites (two tarns harzburgite); Plagioclase lherzolites and plagioclase harzburgites (plagioclase zone); Banded dunite, harzburgite, and lherzolite (Plateau complex); Banded dunite and harzburgite (Ellis Stream complex). Geothermobarometry, major and trace element geochemistry, geochronology, and structural analysis are combined with the geologic mapping to place the history of the rocks in an incipient subduction environment.
The kinematic history of the rocks is ultimately tied to transtensional plate boundary conditions imposed by the foundering of oceanic crust and initiation of subduction along an active oceanic transform margin. The style of strain accommodating transtensional deformation was largely a function of the distribution of melt during exhumation and cooling of the massif. At 1200�� and at pressures >6 kbar (Stage 1), melts were homogeneously distributed, and strain was homogeneous and highly constrictional. At 1000��C and 5 kbar pressure (Stage 2), melts were focused into kilometer scale conduits, and deformation produced lineated and foliated rocks that overprinted the earlier constrictional fabrics. When no melts were present at temperatures less than 600��C (Stage 3), deformation became highly localized into serpentinized faults. In addition to its influence on the kinematic history of the massif, the two stages of melt migration altered the composition of the massif. Early melting associated with the first stage of deformation produced depleted harzburgites with a small range in whole-rock compositions. During Stage 2, melts were channelized and initially undersaturated in orthopyroxene, producing dunite bands. During the waning phases of Stage 2, melts became saturated in clinopyroxene �� plagioclase, resulting in local refertilization of the massif. Refertilization was particularly prevalent along the margins and upper terminations of Stage 2 melt conduits, forming a refertilization front enriched in plagioclase and clinopyroxene, but presumably due to lower melt fluxes, lacking dunite bands. A key result is that melt migration, not any pre-existing compositional heterogeneity, plays a fundamental role in the kinematic history of the massif. Rather, the compositional heterogeneity within the massif is the end result of multiple episodes of melt migration and refertilization during the earliest stages of subduction. Thus the Red Hills ultramafic massif provides a pristine record of how the mantle flows and changes composition as a result of melt migration during the earliest stages of subduction
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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