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Chemical Mohometry
No full textSupplementary data files accompanying the following paper:
Luffi, P. and Ducea, M.N. (2022) Chemical Mohometry: Assessing Crustal Thickness of Ancient Orogens Using Geochemical and Isotopic Data (to be published in Reviews of Geophysics
Chemical Mohometry
No full textSupplementary data files accompanying the following paper:
Luffi, P. and Ducea, M.N. (2022) Chemical Mohometry: Assessing Crustal Thickness of Ancient Orogens Using Geochemical and Isotopic Data (to be published in Reviews of Geophysics
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
Detrital zircon U–Pb ages of metasedimentary rocks from Sierra de Valle Fértil: Entrapment of Middle and Late Cambrian marine successions in the deep roots of the Early Ordovician Famatinian arc
Get PDFWe obtained detrital zircon ages from three metasedimentary rocks with siliciclastic protoliths that were buried to paleodepths of 20 to 27 km during Early Ordovician Famatinian arc magmatism. In all three samples, U-Pb zircon age distributions are polymodal but the dominant peaks make well-defined clusters, matching the ages of orogenic systems that characterize West Gondwana. The most prominent peaks of constituent age populations at 520 Ma, 600 Ma, and 1050 Ma reflect derivation from sources that are characteristic of the West Gondwana margin. Moreover, grains with Meso- and Paleo-Proterozoic ages appear as small fractions ( -5 %). The siliciclastic protoliths to metasedimentary rocks from the deep Famatinian crust are dominantly composed of detritus derived from two sources: 1) a nearby magmatic arc or a rapidly exhuming orogen, and 2) sedimentary recycling of Neoproterozoic-Lower Cambrian sedimentary successions broadly grouped as Puncoviscana Formation. Our findings reveal that granulite-facies metasedimentary rocks in the deep crust of the Famatinian arc have detrital zircon patterns closely resembling those found in nearby Middle to Upper Cambrian quartz-rich turbidite sequences from central Famatina, the Cordillera Oriental and the Puna. At the regional scale, these sedimentary successions yield maximum depositional ages corresponding to the Middle Cambrian (- 520 Ma). This indicates that metasedimentary rocks in the Sierra de Valle Fértil were rapidly buried to deep levels after deposition. Our results are also consistent with the existence of a crustal scale paleo-suture located at the western margin of the Sierras Valle Fértil and La Huerta that explains the differences of detrital zircon age patterns between metasedimentary rocks in the Valle Fértil and age-equivalent sedimentary units in the nearby Cuyania Terrane.Fil: Cristofolini, Eber Ariel. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas, Fisicoquímicas y Naturales. Departamento de Geología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Otamendi, Juan Enrique. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas, Fisicoquímicas y Naturales. Departamento de Geología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; ArgentinaFil: Ducea, M.N.. University of Arizona; Estados UnidosFil: Pearson, D.M.. University of Arizona; Estados UnidosFil: Tibaldi, Alina María. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas, Fisicoquímicas y Naturales. Departamento de Geología; ArgentinaFil: Baliani, I.. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas, Fisicoquímicas y Naturales. Departamento de Geología; Argentin
Variations 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
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
Low-temperature thermochronologic trends across the central Andes, 21-28°S
No full textIn this paper, we merge more than 200 new apatite and zircon (U-Th)/He analyses and 21 apatite fission-track analyses from 71 new samples with previous published thermochronologic data using the same systems to understand the growth and large-scale kinematics of the central Andes between 21°S and 28°S. In general, minimum dates decrease and the total range of dates increases from west to east across the range. Large variations in thermochronometer dates on the east side reflect high spatial gradients in depth of recent erosional exhumation. Almost nowhere in this part of the Andes has Cenozoic erosion exceeded ~6–8 km, and in many places in the eastern half of the range, erosion has not exceeded 2–3 km, despite these regions now being 5–6 km above sea level. This means that west of the rapidly deforming and eroding eastern range front, uplift and erosion are largely decoupled as a result of meager precipitation, relatively low relief, internal drainage, and volcanic burial. We interpret the west-to-east pattern of decreasing minimum dates across the range as recording the time-transgressive eastward migration of a focused zone of deformation, erosion, and convergence between the South American plate and the eastern edge of the Andean orogenic plateau. At this scale, the thermochronologic data do not suggest major changes in rates of plateau propagation or shortening/convergence with time. We use the thermochronometer date-distance trend and a simple kinematic model to infer a rate of eastward propagation of deformation and plateau growth of 6–10 km/m.y. This plateau propagation model balances horizontal convergence, erosion, and crustal thickening and predicts rates of shortening and convergence between the Andes block and South American plate that are consistent with geologic and geodetic observations
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