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Camp Volcanism: age, volcanic stratigraphy and origin of the magmas. Cases studies from Morocco and the U.S.A.
Full text linkDuring Triassic time, in the proto-North Atlantic area, the late Palaeozoic fracture system, inherited from the building of Pangea supercontinent, was reactivated. Rifting and breakup of Pangea, initiated during the early Triassic, continued and intensified at the beginning of the Norian. After few million years later, a massive magmatic event, namely CAMP (Central Atlantic Magmatic Province), occurred in the rifted and inside the cratonic areas, covering more than 10 millions kilometers square, leaving its products on 4 continents: North and South America, southwest Europe and west Africa. The main magmatic event occurred at ca 199-200 Ma near the Triassic-Jurassic boundary (Tr-J) with two minor secondary pulses al ca. 195 Ma and 192 Ma. The time spanned by the main magmatic event is very short, probably less than 1 Ma (ca. 610 Ka based on Milankovitch cyclostratigraphy), and the tight occurrence with one of great extinctions events in the Phanerozoic time and the climatic crisis and biotic turnover demarcating the Tr-J, led to the intriguing hypothesis that CAMP magmatism triggered these global events. At present the CAMP magmatism is represented by tholeiitic dikes, sills and minor amounts of lava flows, deeply eroded and in few places well preserved, being due to the subtropical palaeogeographic position of the basaltic outcrops which led to heavy weathering. Most of the CAMP basalts throughout circum-Atlantic domain have quite homogeneous compositions, with low-Ti (TiO<2wt.%) except for high-Ti dyke storms documented in Liberia, French Guyana and northern Brazil, strong Nb-Ta(PM) negative anomaly, enriched in light earth rare elements (LREE) and large ion lithophile elements (LILE) respect to the common normal mid-ocean ridge basalts. The purpose of this work is to describe and correlate 6 CAMP volcanic sequences in three different Morocco regions (three in the Central High Atlas, two in the Middle Atlas and one in the Western Meseta) on the base of a petrographic-mineralogic-geochemical-magneto-stratigraphic study in order to highlight similarities between the four basaltic units which made up the lava piles. Phase relationships, their major, minor and trace element compositions will be investigated to constrain crystallization order and conditions (T, P, H2O content and fO2) of basalts while the accurate chemo-magneto-stratigraphic correlation of five lava sequence allow to do new suppositions about feeding system of the Moroccan CAMP basalts. Finally new and accurate 40Ar/39Ar dating on plagioclase and biotite separates from 10 basaltic sample of the Eastern North America (Newark and Culpeper basins) will be presented, discussed and compared to both previous dating of the same province and a overall CAMP ages dataset
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
(2007). Time Related Evolution of a Continental Flood Basalt Province: Geochemistry and Magnetostratigraphy of Camp Lava Flow Sequences From the High Atlas, Morocco.
No full textVariations 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
VNIR Spectral comparison between S-Type asteroids and brachinites and ungrouped brachinites-like, in support of the HERA mission
Full text linkAppropriate 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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