1,721,035 research outputs found
Palaeomagnetism in fold and thrust belts: Use with caution
No full textThe application of palaeomagnetism in fold and thrust belts is a unique way to obtain kinematic information regarding the evolution of these systems. However, since many potential problems can affect the reliability of palaeomagnetic datasets and their interpretations, such data should be used with caution. In this paper, we thoroughly review the sources of error from palaeomagnetism with a particular focus on deciphering vertical-axis rotations and the assumptions behind the method. Recent investigations have demonstrated that the age of the magnetization and syn-folding results from the fold test must also be carefully examined: factors such as internal deformation, deficient isolation of components (i.e. overlapping) or incorrect restoration procedures may produce apparent syn-folding results. In fact, the restoration procedure used to return the palaeomagnetic signal to the palaeogeographic coordinate system may itself inhibit accurate estimations of vertical-axis rotations when complex deformation histories induce different, noncoaxial, deformation axes. We recommend the auxiliary use of the inclination v. dip diagram as an efficient tool for identifying many errors. Finally, to determine accurate vertical axis rotations, the reference direction should honour standard reliability criteria and would ideally be measured within the undeformed foreland of the thrust system. In this paper, we review five decades of palaeomagnetic research in fold and thrust belts by concentrating on maximizing standard reliability criteria procedures to reduce uncertainty and increase confidence when applying palaeomagnetic data to unravel the tectonic evolution of fold and thrust belts
Distribution of Effects in the Urban Area of Rome, for the October 14, 1997 (Central Italy) Event
No full textHigh-density macroseismic survey in urban areas. Part 1: proposal for a methodology and its application to the city of Rome
No full textThe role of active strike-slip faults and opposite vertical axis rotations in accommodating eurasia-arabia shortening in central iran
No full textIn Central Iran, most of the Late Cenozoic to Present shortening has been accomplished in the Zagros, in the Alborz, and Kopeh-Dagh mountain ranges. Between these active mountain belts, a minor amount of shortening is observed and the deformation style is characterized by active strike-slip faults that bound relatively aseismic blocks. Two main strike-slip fault systems are presently active in different regions of Central Iran: South of latitude 34 °N, active deformation is accommodated on ∼N–S oriented right-lateral strike-slip faults, and north of latitude 34 °N, E–W left-lateral strike slip faults prevail. In this work, we investigated two different structures, representative of the two different strike-slip systems occurring in Central Iran: the Yazd fold system located in an area dominated by the occurrence of NNW-SSE oriented right-lateral strike slip faults, and the Ferdows fold system that developed at the western termination of the E–W left-lateral strike-slip Dasht-e-Bayaz fault. Paleomagnetic results show opposite vertical-axis rotations related to the different orientation and sense of movement of strike-slip fault systems, suggesting that in Central Iran the N–S oriented right-lateral and E–W oriented left-lateral strike-slip faults play significant roles in accommodating the Arabia-Eurasia convergence, by rotating counterclockwise and clockwise in the horizontal plane, respectively
The origin of tectonic fabrics in ‘‘undeformed’’ clays: The early stages of deformation in extensional sedimentary basin
No full textAn integrated approach was used to detect tectonic
effects in apparently undeformed fine-grained clay sediments
filling extensional basins in Southern Italy. Results from low
and high field anisotropy of magnetic susceptibility and
mineral fabric, deduced by neutron texture analysis, show
penetrative deformation on a grain-scale. The well-defined
tectonic magnetic lineation is parallel to the stretching
direction and located at the intersection of the basal planes of
phyllosilicates, forming grain-scale folds and crenulations.
This spatial configuration reflects basin scale deformation
processes and suggests the existence of a nearly uniaxial
stress field during the incipient extensional phases. The
integrated approach of magnetic and mineral fabric
investigations is a valid tool to detect grain scale and
regional deformation pattern in weakly deformed extensional
basins, where macroscopic evidence of deformation is not
visible
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
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