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Abstract:

Beneath much of the Andes, oceanic lithosphere descends eastward into the mantle at an angle of about 30° (ref. 1). A partially molten region is thought to form in a wedge between this descending slab and the overlying continental lithosphere as volatiles given off by the slab lower the melting temperature of mantle material. This wedge is the ultimate source for magma erupted at the active volcanoes that characterize the Andean margin. But between 28° and 33° S the subducted Nazca plate appears to be anomalously buoyant, as it levels out at about 100 km depth and extends nearly horizontally under the continent. Above this 'flat slab', volcanic activity in the main Andean Cordillera terminated about 9 million years ago as the flattening slab presumably squeezed out the mantle wedge. But it is unknown where slab volatiles go once this happens, and why the flat slab finally rolls over to descend steeply into the mantle 600 km further eastward. Here we present results from a magnetotelluric profile in central Argentina, from which we infer enhanced electrical conductivity along the eastern side of the plunging slab, indicative of the presence of partial melt. This conductivity structure may imply that partial melting occurs to at least 250 km and perhaps to more than 400 km depth, or that melt is supplied from the 410 km discontinuity, consistent with the transition-zone 'water-filter' model of Bercovici and Karato.

Registro:

Documento: Artículo
Título:Low electrical resistivity associated with plunging of the Nazca flat slab beneath Argentina
Autor:Booker, J.R.; Favetto, A.; Pomposiello, M.C.
Filiación:Dept. of Earth and Space Sciences, Box 351310, University of Washington, Seattle, WA 98195, United States
Inst. de Geocronol. y Geol. Isotop., Ciudad Universitaria, Pabellón INGEIS, 1428 Buenos Aires, Argentina
Palabras clave:Electric conductivity; Geology; Mathematical models; Melting; Water; Conductivity structure; Volatiles; Volcanoes; electrical resistivity; Nazca plate; oceanic lithosphere; plate tectonics; subduction zone; Argentina; article; electric conductivity; electric resistance; melting point; priority journal; sea; volcano; Argentina; South America
Año:2004
Volumen:429
Número:6990
Página de inicio:399
Página de fin:403
DOI: http://dx.doi.org/10.1038/nature02565
Título revista:Nature
Título revista abreviado:Nature
ISSN:00280836
CODEN:NATUA
Registro:https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00280836_v429_n6990_p399_Booker

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Citas:

---------- APA ----------
Booker, J.R., Favetto, A. & Pomposiello, M.C. (2004) . Low electrical resistivity associated with plunging of the Nazca flat slab beneath Argentina. Nature, 429(6990), 399-403.
http://dx.doi.org/10.1038/nature02565
---------- CHICAGO ----------
Booker, J.R., Favetto, A., Pomposiello, M.C. "Low electrical resistivity associated with plunging of the Nazca flat slab beneath Argentina" . Nature 429, no. 6990 (2004) : 399-403.
http://dx.doi.org/10.1038/nature02565
---------- MLA ----------
Booker, J.R., Favetto, A., Pomposiello, M.C. "Low electrical resistivity associated with plunging of the Nazca flat slab beneath Argentina" . Nature, vol. 429, no. 6990, 2004, pp. 399-403.
http://dx.doi.org/10.1038/nature02565
---------- VANCOUVER ----------
Booker, J.R., Favetto, A., Pomposiello, M.C. Low electrical resistivity associated with plunging of the Nazca flat slab beneath Argentina. Nature. 2004;429(6990):399-403.
http://dx.doi.org/10.1038/nature02565