1,721,026 research outputs found
Structure and metamorphism of the Cushamen Complex in Sañicó and Collón Curá-limay rivers confluence: A Devonian metamorphic event related to the subduction stage of the Gondwanan Patagonian orogen
Get PDFIn the North Patagonian Andes and western North Patagonian Massif, the Cushamen Complex is still a matter of interest in order to unravel the Paleozoic evolution of southwestern Gondwana margin. In this contribution we present new petrographic and structural data from the Cushamen Complex cropping out nearby Sañicó town and Collón Curá and Limay rivers confluence together with U–Pb (Q-ICP-MS) detrital zircon ages. In these areas, this metamorphic complex is composed of migmatites, orthogneisses and calcsilicate rocks, with a Late Devonian metamorphic peak age, intruded by Devonian - lower Carboniferous granites. The regional metamorphic peak would also has been accompanied by the development of a pervasive tectonic foliation and associated isoclinal folds. Devonian - Carboniferous granites crosscut the foliation of the migmatites and would have produced a weak contact metamorphism represented by static recrystallization in quartz grains. The regional metamorphic event can be related to the subduction-related Gondwanan orogenic event. At least two more folding phases and related foliations were identified postdating these granitic intrusions, probably related to the collisional event of the Gondwanan orogeny, late Carboniferous - early Permian in age. Evidence of retrograde metamorphism probably related to the previously mentioned foliations and folds are common. Zircons from a mesosome were analyzed by U–Pb Q-ICP-MS yielding a maximum depositional age of 441.79 ± 1.68 Ma (early Silurian/Rhuddanian) indicating a sedimentation for the protholits probably during middle Silurian, age of the pre-orogenic successions of the Gondwanan cycle in Patagonia.Fil: Dicaro, Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigación en Paleobiología y Geología; Argentina. Universidad Nacional del Comahue. Facultad de Ingeniería. Departamento de Geología y Petróleo; ArgentinaFil: González, Santiago Nicolás. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigación en Paleobiología y Geología; ArgentinaFil: Serra Varela, Samanta. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigación en Paleobiología y Geología; Argentina. Universidad Nacional del Comahue. Facultad de Ingeniería. Departamento de Geología y Petróleo; ArgentinaFil: Heredia, Nemesio. Instituto Geológico y Minero de España; Españ
Modelado del equilibrio de fases de la fusión parcial del basamento Paleozoico de San Martín de los Andes
Get PDFFil: Serra Varela, Samanta. Universidad Nacional de Río Negro. Instituto de Investigación en Paleobiología y Geología. Río Negro, Argentina.Fil: González, Pablo Diego. Universidad Nacional de Río Negro. Instituto de Investigación en Paleobiología y Geología. Río Negro, Argentina.Fil: Giacosa, Raúl. Servicio Geológico Minero Argentino (SEGEMAR), Delegación Comahue; Argentina.Fil: Heredia, Nemesio. Instituto Geológico y Minero de España; España.This work is focused on the determination of P-T conditions for the and pressure of this event between 680° and 736°C and 4-5.4 kbar metamorphic rocks in San Martin de Los Andes area that have reached anatectic conditions. Basement rocks in this area comprise high-grade Lower Paleozoic metamorphic rocks from Northpatagonian Andes. In order to accomplish this, microtextural analysis, pseudosection modelling and a conventional geothermometer have been used. The combination of these methods allows us to constrain the temperature
The poly-orogenic Paleozoic rocks of Cuesta del Rahue area (Precordillera Neuquina, Argentina) and their significance in marking the southern end of the Chanic orogenic belt
No full textIn the Cuesta del Rahue area, located in the Precordillera Neuquina (northern Argentine Patagonia), late Paleozoic turbiditic rocks with maximum depositional age of ca. 389 Ma were affected by three orogenic events. The oldest orogenic event is the Chanic orogeny (Late Devonian–early Carboniferous) that is characterized by folds with NNE vergence. This deformation is developed in low-grade to very low-grade metamorphic conditions, which allowed the development of a slaty/rough cleavage. The main Chanic structure is an asymmetric fold with a large normal limb tilted by the more recent orogenic events. The characteristics of the deformation and metamorphism allows us to assign the Cuesta del Rahue outcrop to the external hinterland of the western wedge of the Chanic orogen. Early to late Carboniferous igneous rocks intruded the Paleozoic rocks of the Cuesta del Rahue area and crosscut the Chanic structures. After the Chanic orogeny, the Gondwanan orogeny (late Carboniferous–early Permian) took place. The main structures of the Gondwanan orogen are thrust and related folds with SSW vergence that fold the large Chanic normal limb and also affect Carboniferous igneous rocks. The Gondwanan deformation was developed under non-metamorphic conditions, and Permian igneous rocks crosscut the Gondwanan structures. Mesozoic regional extension related to the beginning of the Andean cycle and the formation of the Neuquén Basin gave rise to normal faults and small-scale extensional folds. Finally, the Andean orogeny, developed during the Cenozoic in the study area, also affected the Cuesta del Rahue Paleozoic rocks, with the development of compressional structures related to the Aluminé thrust and fold belt. The main Andean structure in the study area is the NW–SE Rahue fault, which links the E–W Piedra Santa tear fault with the NNE–SSW Cantan Lil reverse fault. The Rahue fault has a SW tectonic transport direction. It uplifted the Cuesta del Rahue area and placed Paleozoic rocks on top of Mesozoic and Cenozoic rocks. The Piedra Santa fault partially reactivated the Huincul right-lateral and left-lateral Chanic transverse faults that define the southern end of the doubly vergent Chanic orogen, giving rise to the current Huincul lineament.Fil: Heredia, Nemesio. Instituto Geológico y Minero de España; EspañaFil: Pedreira, David. Universidad de Oviedo; EspañaFil: Giacosa, Raul Eduardo. Secretaría de Industria y Minería. Servicio Geológico Minero Argentino; Argentina. Universidad Nacional de Río Negro. Sede Alto Valle. Instituto de Investigaciones en Paleobiología y Geología; ArgentinaFil: Serra Varela, Samanta. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigación en Paleobiología y Geología; ArgentinaFil: Foix, Nicolas. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de la Patagonia "San Juan Bosco"; ArgentinaFil: Allard, José. Universidad Nacional de la Patagonia "San Juan Bosco"; ArgentinaFil: González, Pablo. Secretaría de Industria y Minería. Servicio Geológico Minero Argentino; ArgentinaFil: Martín González, Fidel. Universidad Rey Juan Carlos; Españ
Las estructuras Chánicas en el Bloque San Rafael (Provincia de Mendoza, Argentina)
No full textEn el basamento paleozoico pre-carbonífero del Bloque San Rafael, las rocas situadas al este del Cabalgamiento gondwánico de Los Reyunos muestran estructuras chánicas (pre-carboníferas) vergentes al este y generadas en ausencia de metamorfismo, mientras las situadas al oeste de dicho accidente fueron deformadas en condiciones metamórficas de bajo grado por dos sistemas de pliegues, el primero de los cuales es, por lo general, vergente al oeste. Por esta razón el Cabalgamiento de Los Reyunos debe interpretarse como una reactivación de un accidente chánico, responsable de la superposición de la rama occidental del Orógeno Chánico sobre la rama Oriental del mismo, producida como consecuencia de la colisión entre Chilenia y Cuyania.Fil: Farias, Pedro. Universidad de Oviedo; EspañaFil: García Sansegundo, Joaquín. Universidad de Oviedo; EspañaFil: Rubio Ordoñez, A.. Universidad de Oviedo; EspañaFil: Clariana, Pilar. Instituto Geológico y Minero de España; EspañaFil: Cingolani, Carlos Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Geológicas. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Investigaciones Geológicas; ArgentinaFil: Heredia, Nemesio. Instituto Geológico y Minero de España; EspañaIX Congreso Geológico EspañolHuelvaEspañaAsociación Geológica de EspañaInstituto Geológico y Minero de EspañaUniversidad de Huelv
El basamento Paleozoico polideformado en la confluencia de los Ríos Collón Curá, borde noroccidental del Macizo Norpatagónico, provincia de Neuquén
No full textFil: Serra Varela, Samanta. Universidad Nacional de Río Negro. Instituto de Investigación en Paleobiología y Geología. Río Negro, Argentina.Fil: González, Santiago. Universidad Nacional de Río Negro. Instituto de Investigación en Paleobiología y Geología. Río Negro, Argentina.Fil: Dicaro, Sebastián. Universidad Nacional del Comahue, Facultad de Ingeniería, Dpto. de Geología y Petróleo; Argentina.Fil: Heredia, Nemesio. Instituto Geológico y Minero de España; Argentina.Fil: Giacosa, Raúl. Servicio Geológico Minero Argentino (SEGEMAR); Argentina.El basamento paleozoico ubicado al oeste del Macizo Norpatagónico aflora sobre la RN 237 y RN 234, 70 km al Sur de Piedra del Águila y está compuesto de esquistos y migmatitas estromatíticas que son la roca de caja de cuerpos graníticos. Estas rocas fueron asignadas a la Formación Cushamen y a la Formación Mamil Choique, respectivamente (Varela et al. 1991; Dalla Salda et al. 1999). Los cuerpos graníticos fueron datados en ca. 348 Ma (Carbonífero inferior; U-Pb TIMS en circones) por Varela et al. (2005) por lo que la evolución tectono-metamórfica de este basamento sería previa a esa edad, alcanzando el pico metamórfico entre los 380 y 360 Ma (Devónico Superior) acorde a dataciones U-Pb de titanitas (Lucassen et al. 2004)
Condiciones físicas del metamorfismo de alta temperatura y baja presión del basamento del Paleozoico inferior en el área de San Martín de los Andes, Neuquén
No full textFil: Serra Varela, Samanta. Universidad Nacional de Río Negro. Instituto de Investigación en Paleobiología y Geología. Río Negro, Argentina.Fil: González, Pablo Diego. Universidad Nacional de Río Negro. Instituto de Investigación en Paleobiología y Geología. Río Negro, Argentina.Fil: Giacosa, Raúl. Servicio Geológico Minero Argentino (SEGEMAR), Delegación Comahue; Argentina.Fil: Heredia, Nemesio. Instituto Geológico y Minero de España; España.Fil: Sato, Ana María. Centro de Investigaciones Geológica (CIG), UNLP- CONICET; Argentina.Metamorphic basement rocks of San Martín de los Andes area comprise schists, gneisses and migmatites. They are intruded by Devonian granitoids that cut the metamorphic internal structure of these rocks. This basement belongs to a pre-Gondwanan cycle and its regional extension in the Nordpatagonian Andes is unknown. Petrographic analysis and pseudosections allowed us to determine physical parameters in order to characterize the metamorphic conditions. P-T conditions for migmatites range between 710° and 740°C below 0.44GPa. These conditions correspond to a low pressure ? high temperature (LP-HT) metamorphism between amphibolite and granulite facies. Considering its metamorphic characteristics and age (pre-Devonian), no equivalent rocks have yet been found in nearby areas with outcrops of pre-Andine basement
The Paleozoic evolution of the Andes and its foreland: Introduction
Get PDFIn the southern part of the Andean Cordillera and nearby areas of its foreland, located in the Bolivian, Chilean and Argentinian territory, there are Paleozoic basement relicts of variable extension, which formed part of the W and SW margin of Gondwana. This basement has been involved in orogenic events prior to the Andean orogeny (active from the Cretaceous to the present), some of which starts in the Neoproterozoic or reach the beginning of the Mesozoic. During the Paleozoic and according to Heredia et al. (2016, 2018), a set of continental fragments of variable extent and allochtony was successively accreted to the Gondwana margin, resulting in six Paleozoic orogenies of different temporal and spatial extension: Pampean (Ediacaran-early Cambrian), Famatinian (Middle Ordovician-Silurian), Ocloyic (Middle Ordovician-Devonian), Chanic (Middle Devonian-early Carboniferous), Gondwanan (Middle Devonian-middle Permian) and Tabarin (late Permian-Triassic). All these orogenies culminate with collisional events, with the exception of the Tabarin and the Gondwanan north of 39º S that are subduction-related.Fil: Serra Varela, Samanta. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigación en Paleobiología y Geología; ArgentinaFil: García Sansegundo, J.. Universidad de Oviedo; EspañaFil: Heredia, N.. Instituto Geológico y Minero de España; Españ
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
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