1,721,068 research outputs found
The early stages of the Alpine collision: An image derived from the upper Eocene-lower Oligocene record in the Alps-Apennines junction area
No full textThe upper Eocene-lower Oligocene sediments deposited in the eastern part of the Tertiary Piedmont Basin in northern Italy provide a complete record of the unroofing of the Alpine orogenic prism during the early stages of exhumation in the Ligurian sector. From late Priabonian till late Rupelian time, the sediments in the study area were derived from two different sources, one characterised by white micas with Si7 pfu and Eocene-Oligocene 40 Ar/ 39 Ar ages (32-50 Ma). The first source is considered to be indicative of low-pressure metamorphic rocks that covered the HP rocks of the Ligurian Alps, and were completely eroded by Chattian time. From this time on, the study area started to record the first input from western Alpine sources characterised by a larger span of ages with a more frequent Eoalpine signal. Thus, sediments deposited in the eastern part of the Tertiary Piedmont Basin contain the only available evidence of rocks belonging to high crustal levels in the Alpine orogenic prism that were not affected by the Alpine overprint. These data also provide time constraints to the poorly dated first conglomerates deposited in this area. 40 Ar/ 39 Ar geochronology reveals a minimum age of 33±1.4 Ma for the Pianfolco Conglomerates in the type locality, and of 31.4±3.5 Ma for the Borbera Conglomerates
40Ar/39Ar detrital thermochronology on Eocene-Oligocene sediments of the Alps-Apennines junction area provides insights on the early stages of the Alpine orogenesis.
No full textFacies analysis, Ar/Ar dating and mineral chemestry: tools for studying paleogeography in a subsiding collisional belt (Ligurian Alps, Italy).
No full textA provenance study of a post-collisional transgressive sequence (Molare Formation, Italy) through integrated facies analysis, mineral chemistry and Ar/Ar dating.
No full textCoupled U–Pb and 40Ar/39Ar chronology of late-stage intrusions at Elba Island (Italy) supports late Miocene long-lived magma reservoirs in the Tyrrhenian upper crust
No full textThe late Miocene Monte Capanne and Porto Azzurro plutons are investigated by means of coupled U-Pb zircon and Ar-40/Ar-39 white mica dating to test the occurrence of long-lived magmatic systems in the upper crust. Zircon crystallized for >1 Ma in both plutonic systems, with supersolidus conditions overlapping for similar to 220 ka indicating previously unrecognized co-existence of the two reservoirs. The development of the Porto Azzurro high T-aureole is post-dated by continuous igneous zircon crystallization until similar to 6.0 Ma. By linking crystallization to post-emplacement cooling of late-stage pulses in both western and eastern Elba we constrain long-lived sizeable reservoirs (possibly the same reservoir) in the Tyrrhenian upper crust between similar to 8 and 6 Ma
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
Provenance of Oligocene synorogenic sediments of the Ligurian Alps (NW Italy): inferences on belt age and cooling history
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