1,721,105 research outputs found
Dinámica de zonas de subducción y evolución tectono-estratigráfica de antearco: cuenca Talara, noroeste del Perú
Get PDFForearc basins are important archives for understanding the tectonic evolution of the plate margin and subduction zone through deep time because they preserve a tectonostratigraphic record of temporal and spatial interactions of eustasy, sediment supply, climate, basin physiography and tectonism. However, forearc basins have received less attention than rift and foreland basins, due to the limited number of exposed examples and classification traditionally restricted to accretionary margins. The Talara Basin in the northern Peruvian forearc, where the oceanic Nazca plate is being subducted beneath the continental South American plate, is a well-known example of a subduction-erosion margin, where the edge of the continental plate is consumed over time and accretionary processes play a minor role. From the Late Cretaceous to the Eocene, stratigraphic units from deep water to fluvial environments comprise a 9 km-thick basin fill that has been episodically deformed by extensional faulting due to forearc vertical movements produced by subduction. This work aims to characterise the spatial and temporal behaviour of subduction and how these processes are recorded in and affect the evolution of the forearc basin. The sequence stratigraphic approach is based on the integration of outcrop, well and seismic data sets. Sedimentology and analysis of stratal stacking patterns and key stratigraphic surfaces, integrated with tectonic studies show that the Eocene Parià ±as Formation comprises three depositional sequences of fluvio-deltaic deposits that form a highstand sequence set. The succession is capped by a previously unrecognised composite sequence boundary marked by a regional palaeosol and overlain by the transgressive sequence set of the Chacra Formation. The composite sequence boundary may indicate the presence of a lowstand sequence set offshore. This integrated PhD project identified tectonically-enhanced/driven regressions and transgressions through the Eocene. Down-dip and across-strike system asymmetry was a response to uplift and extensional collapse events related to periods of locking and release of the subduction interface. These observations highlight the importance of a close temporal and spatial relationship between plate boundary and basin - a relationship unique to forearc basins, with worldwide application.El área de estudio es la cuenca Talara, localizada en el norte del antearco peruano, en la margen convergente entre las placas de Nazca y Sudamérica. Los principales análisis realizados en este trabajo consisten en la interpretación geológica de sísmica de reflexión y sus atributos, análisis y correlación de registros de pozo, descripción de núcleos, muestreo y levantamiento estratigráfico de afloramientos, análisis bioestratigráfico, y petrografía de secciones delgadas. Estos análisis a multi-escala (cuenca–microscopio) están basados en la integración de los datos empleados, tanto en tierra como costa afuera. La motivación fundamental de este trabajo es abordar la brecha de conocimiento sobre cómo el proceso de subducción influye en la estratigrafía secuencial de antearco, especialmente en escenarios de subducción con erosión, ya que el grado de influencia de los factores que controlan la sedimentación en márgenes convergentes tectónicamente activas no está bien identificado como en otras cuencas, debido a la falta de previos trabajos. Los objetivos específicos de este estudio son tres: (i) caracterizar y clasificar los procesos de subducción de la margen continental del norte peruano; (ii) caracterizar la geodinámica de antearco en el tiempo; (iii) construir modelos estratigráfico-secuenciales y tectónicos para entender las condiciones paleoambientales de sedimentación.Perú. Programa Nacional de Becas y Crédito Educativo (Pronabec). Beca Generación del BicentenarioTesi
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
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Cenozoic uplift and denudation of southern Norway:Insights from the North Sea Basin
No full textThe Cenozoic evolution of the North Sea Basin is described, drawing on subsurface data and a series of palaeogeographical maps compiled from a variety of published studies, mainly emphasizing the development of the eastern part of the basin. A model that accounts for the sedimentation history of the North Sea Basin and the topography (including maximum and mean surface elevation) of southern Norway is proposed. The model involves regional plume-related uplift of an initial low-elevation peneplain in early Paleogene time followed by repeated episodes of climatic deterioration and eustatic fall, most notably at the Eocene-Oligocene transition, in late Mid-Miocene time, and eventually culminating with the development of full glacial conditions in southern Norway in Plio-Pleistocene time. These episodes correspond to periods of accelerated sediment supply from southern Norway that reflect increased rates of incision (dissection) of the source area. It is argued that the present-day elevation of > 2km of mountain peaks in southern Norway adjacent to deep valleys and fjords could have been caused by isostatic uplift in response to dissection of a high-elevation peneplain. Hence it may not be necessary to invoke late Cenozoic tectonic uplift events to explain the present-day topography of southern Norway.</p
Sandstone intrusions:Implications for exploration and production
No full textSandstone intrusions, or sand injectites, are the natural product of syn-or post-depositional remobilization and injection of sand into surrounding strata due to overpressure, hydrocarbon migration, and seismicity. Reservoir-scale sandstone intrusions are likely to occur across all continents and in all sedimentary environments. Unlike small-scale sandstone intrusions that are often used to infer ancient earthquakes in continental sequencer, the km-scale sand injectities discovered in the North Sea are difficult to understand both in terms of driving and triggering mechanisms. The importance of sandstone intrusions for E&T includes reservoir occurrence, architecture and flow properties, inter-and intra-reservoir connectivity, fluid migration and drilling hazards.</p
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