1,721,227 research outputs found
Conodont biostratigraphy of the Upper Devonian-Lower Carboniferous Shahmirzad section, central Alborz, Iran
No full textThe conodont fauna from the Devonian–Carboniferous Shahmirzad section, located in the Central Alborz Mountains (North Iran), have been studied mainly for biostratigraphic purposes. Some levels were barren of conodonts, whereas others yielded a not very abundant, but quite differentiated fauna. No conodonts have been found from the mainly terrigenous and shaly Geirud Formation, whereas representative of genera Bispathodus, Clydagnathus, Gnathodus, Hindeodus, Mehlina, Polygnathus, Protognathodus, Pseudopolygnathus and Siphonodella have been collected from the mainly calcareous overlaying Mobarak Formation. The fauna allowed to discriminate five biointervals, from the sulcata Zone to a “Lower typicus – anchoralis-latus interval” in the central part of the section, while the lower and upper parts cannot be zoned on the basis of conodonts. This paper is the first report on lowermost Carboniferous conodonts from the Mobarak Formation in central Alborz
Upper Devonian-Lower Carboniferous conodont biostratigraphy in the Shotori Range, Tabas area, Central-East Iran Microplate
Full text linkA rich and diverse conodont fauna represented by fifty-six taxa belonging to fifteen genera is described from three sections (Ghale-kalaghu, Howz-e-Dorah 1 and Howz-e-Dorah 2) in the southern Shotori Range (central Iran). The association, dominated by Polygnathus, has allowed a detailed biostratigraphy across the Devonian/Carboniferous boundary interval to be constructed, ranging from the Uppermost marginifera Zone to the anchoralis-latus Zone. The D/C boundary is narrowly constrained within a condensed interval at the base of the "Mush Horizon" between the Shishtu 1 and Shishtu 2 subformations
Conodont biostratigraphy of the upper Frasnian-lower Famennian transitional deposits in the Shotori Range, Tabas area, central-east Iran Microplate
Full text linkA rich and diverse conodont fauna from upper Frasnian and lower-middle Famennian strata in three sections - Ghale-kalaghu, Howz-e-dorah 1 and Howz-e-dorah 2 - in the southern Shotori Range of central Iran contains forty-five taxa belonging to eight genera, dominated by icriodids and polygnathids, from the Lower rhenana Zone to the velifer Zone (= Uppermost marginifera Zone). A hiatus is documented across the Frasnian/Famennian boundary that possibly includes the Upper rhenana to the Middle triangularis Zone
Geochemistry and petrology of the Kermanshah ophiolites (Zagros belt, Iran) an evidence for the Neo-Tethyan magmatism in the northern Arabian realm.
No full textThe Kermanshah ophiolitic complex consists of a mélange formation including dismembered ophiolitic sequences. These ophiolites are located along the Main Zagros Reverse Fault, which marks the ophiolitic suture zone between the Zagros belt and the Sanandaj-Sirjan zone. They represent the Neo-Tethyan oceanic lithosphere originally existing between the Arabian (to the south) and Eurasian (to the north) continental margins. The Kermanshah ophiolites were emplaced onto platform carbonate rocks representing the Northeastern Arabian margin.
The Kermanshah ophiolitic complex is composed of various partial sequences including: mantle tectonites; gabrro and cumulate gabbro;
(with isotropic, pegmatoid and foliated texture) and very scarce pillow basalts. Petrographic observations, mineral chemistry, wholerock chemistry, and rare earth element (REE) modelling carried out on mantle tectonites and intrusive rock associations point out for the following conclusions. (1) The foliated gabbroic sequence has NMORB chemical signature. (2) The pegmatoid gabbroic sequence shows an E-MORB signature. Comparison with the well-studied Oman ophiolites suggests that this sequence may have formed during the early stage of oceanic spreading. (3) The depleted lherzolites show mild depletions in HREE and variable depletion in LREE. REE modelling shows that they may represent a residual mantle after 15-20% removal of N-MORB melts. Some lherzolites show a moderate enrichment in La and Ce with respect to Sm, suggesting that this residual MORB mantle was subsequently trapped in a suprasubduction zone (SSZ) mantle wedge and enriched in LREE by subduction-derived fluids. (4) The depleted harzburgites have a significant depletion in incompatible and REE, coupled with a marked LREE enrichment with respect to medium REE. REE modelling shows that they may represent residual a mantle after 25-30% removal of boninitic-type melts in an intra-oceanic arc setting
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
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