1,720,958 research outputs found
Tectonic magnetic lineation and oroclinal bending of the Alborz range: Implications on the Iran-Southern Caspian geodynamics
No full textIn this study we use the anisotropy of magnetic susceptibility (AMS) and paleomagnetic data for deciphering the origin of magnetic lineation in weakly deformed sedimentary rocks and for evaluating oroclinal processes within the Arabia-Eurasia collision zone. In particular, we have analyzed the Miocene Upper Red Formation (URF) from the outer curved front of the southern Central Alborz Mountains of north Iran, to test for the first time with paleomagnetic data the origin (primary versus secondary) of this orogenic arc. AMS data document the existence of a magnetic lineation parallel to the orientation of the major tectonic structures, which vary along strike from WNW to ENE. These directions are highly oblique to the paleoflow directions and hence suggest that the magnetic lineation in the URF was produced by compressional deformation during layer-parallel shortening. In addition, our paleomagnetic data document clockwise and anticlockwise rotations along vertical axis for the western and eastern sectors of the Central Alborz Mountains, respectively. Combined, our results suggest that the orogen represents an orocline, which formed not earlier than circa 7.6Ma most likely through bending processes caused by the relative motion between the rigid crustal blocks of the collision zone. Moreover, our study provides new insights into the Iran-Southern Caspian Basin kinematic evolution suggesting that the present-day SW motion of the South Caspian Basin with respect to Central Iran postdates oroclinal bending and hence cannot be as old as late Miocene to early Pliocene but a rather recent configuration (i.e., 3 to <1Ma)
Inversion of Cimmerian extensional structures: insights on the tectonic evolution of the Central Alborz, Iran
No full textCentral Alborz is a significant example of inversion tectonics related to the long and complex evolution which accompanied this poorly known segment of the Alpine-Himalayan orogenic system. Extensional structures forming grabens were activated during Late Triassic just south of the collision zone in the stable foreland of the North Iranian block, possibly due to peripheral bulging, in response to the Cimmerian orogeny. Normal faulting at the end of the Cimmerian orogeny, producing block tilting and horst and graben structures before the deposition of the Shemshak Formation, has been also recognized in the of the Iranian block long time ago (STOECKLIN, 1968). In Central Alborz, extensional structures were inverted as sub-parallel right lateral strike-slip or highangle reverse faults. These pre-existing discontinuities can be responsible for the partitioning of strain along faults parallel to the trend of the belt, in response to an oblique convergence, as suggested by the present-day evolution of the belt, where both strike-slip and wrench faults are active (JACKSON et alii, 2002). The reactivation of pre-existent faults as strike-slip structures was also hypothesized by ALLEN et alii (2003), but it was never demonstrated before. The evolution recognized around the «Sharistanak klippe» can be extrapolated also to other parts of the belt, where «anomalous» faults stack young units above older rocks. This is the case of several faults occurring along the axial zone of Central Alborz, which result from the inversion of pre-existent normal faults. In the Sharistanak and Gajere grabens stratigraphic evidence suggests that the extensional structures were coeval to the Cimmerian orogeny. In other cases normal faults can be attributed to older extensional events related with the evolution of the Paleo- and -Tethyan passive margins, as indicated by important facies changes and thickness variations across the belt, as in the case of the Kandevan Fault. Elsewhere, the younger post-Triassic extension related to the opening of the Paleo-Caspian basin (BRUNET et alii, 2003), or which accompanied the deposition of the Eocene volcanics, can be responsible for the activation of extensional structures. The reconnaissance of inversion processes changes the general interpretation of the Central Alborz and can explain several of its features. The gentle deformation observed in the axial part of the Central Alborz north of the Kandevan fault suggests that strain was localized along the high-angle pre-existing tectonic discontinuities, which especially outcrop in the southern part of the belt. In this way mild or total inversion occurred along inherited high-angle normal faults. Tight folds with vertical axial planes developed within the paleo-fault blocks due to buttressing effects induced by the obstacle created by pre-existent high angle normal faults. This phenomenon, which has been analysed in detail in the «Sharistanak klippe», is also evident just south of the Kandevan fault, where Eocene and Miocene successions, detached from their substratum, are affected by isoclinal folds with very steep axial planes showing no clear vergence. Due to the occurrence of steep normal faults, the formation of shortcut thrust planes is favoured, producing «floating horses» (BUTLER, 1989) of Cambrian to Pre-Cambrian rocks along the paleo-graben shoulders, which are stacked above the Tertiary succession in the external part of the belt. In this new interpretation, high t
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
- …
