1,721,046 research outputs found
The Emeishan large igneous province: Advances in the stratigraphic correlations and petrogenetic and metallogenic models
No full textDistribution of platinum-group elements in magmatic and altered ores in the Jinchuan intrusion, China: an example of selenium remobilization by postmagmatic fluids
No full textThe division of platinum-group elements (PGE) between those hosted in platinum-group minerals (PGM) versus those in solid solution in base metal sulfides (BMS) has been determined for ores from the PGE-bearing Ni-Cu-rich Jinchuan intrusion in northwest China. All the BMS are devoid of Pt and Ir, and magmatic BMS are also barren of Rh. These PGE may have been scavenged by arsenic to form PGM during magmatic crystallization of the BMS. Pd, Os, and Ru are recorded in BMS and Pd is predominantly in solid solution in pentlandite. Unlike the fresh magmatic ores, in altered or serpentinized ores, Pd-PGM are present. Froodite is hosted in magnetite, formed during alteration of BMS, accompanied by sulfur loss and liberation of Pd. Michenerite ([Pd,Pt]BiTe), sperrylite (PtAs2), and Au-bearing PGM are located in altered silicates. Irarsite (IrAsS) occurs mainly enclosed in BMS. Padmaite (PdBiSe), identified at the junctions of magnetite and BMS, was the last PGM to form and locally partially replaces earlier non-Se-bearing PGM. We propose that padmaite formed under oxidizing conditions during late local remobilization of Se from the BMS. Se-bearing PGM are rare and our review shows they are frequently associated with carbonate, suggesting that Pd and Se can be mobilized great distances in low pH oxidizing fluids and may be precipitated on contact with carbonate. S/Se ratios are used by researchers of magmatic Ni-Cu-PGE ores to determine sulfur loss, assuming Se is immobile and representative of magmatic sulfur content. This study shows that Se as well as S is potentially mobile and this should be considered in the use of S/Se ratios
Flood basalt-related Fe-Ti oxide deposits in the Emeishan large igneous province, SW China
No full textOrigin of PGE-Poor and Cu-Rich Magmatic Sulfides from the Kalatongke Deposit, Xinjiang, Northwest China
No full textFlood basalt-related Fe-Ti oxide deposits in the Emeishan large igneous province, SW China (vol 119, pg 123, 2010)
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Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Differentiation of nelsonitic magmas in the formation of the similar to 1.74 Ga Damiao Fe-Ti-P ore deposit, North China
No full textVariations on the Author
Get PDF“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
Get PDFWe 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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