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Abstract:

We present a three-dimensional (3-D) interpretation of 117 long period (20-4096 s) magnetotelluric (MT) sites between 31°S and 35°S in western Argentina. They cover the most horizontal part of the Pampean shallow angle subduction of the Nazca Plate and extend south into the more steeply dipping region. Sixty-two 3-D inversions using various smoothing parameters and data misfit goals were done with a nonlinear conjugate gradient (NLCG) algorithm. A dominant feature of the mantle structure east of the horizontal slab is a conductive plume rising from near the top of the mantle transition zone at 410 km to the probable base of the lithosphere at 100 km depth. The subducted slab is known to descend to 190 km just west of the plume, but the Wadati-Benioff zone cannot be traced deeper. If the slab is extrapolated downdip it slices through the plume at 250 km depth. Removal of portions of the plume or blocking vertical current flow at 250 km depth significantly changes the predicted responses. This argues that the plume is not an artifact and that it is continuous. The simplest explanation is that there is a "wedge"-shaped slab window that has torn laterally and opens down to the east with its apex at the plume location. Stress within the slab and seismic tomography support this shape. Its northern edge likely explains why there is no deep seismicity south of 29°S. Key Points Electrically conductive plume in Argentina's asthenosphere suggests slab window Three-dimensional magnetotelluric inversion is required for data presented ©2013. American Geophysical Union. All Rights Reserved.

Registro:

Documento: Artículo
Título:Electrical conductivity of the Pampean shallow subduction region of Argentina near 33 S: Evidence for a slab window
Autor:Burd, A.I.; Booker, J.R.; Mackie, R.; Pomposiello, C.; Favetto, A.
Filiación:Department of Earth and Space Sciences, University of Washington, Box 351310, Seattle, WA 98195, United States
Land General Geophysics, CGG, Milan, Italy
Instituto de Geocronología y Geología Isotopíca, Universidad de Buenos Aires, CONICET, Buenos Aires, Argentina
Palabras clave:Nazca flat slab subduction; slab window; three-dimensional magnetotelluric inversion; Magnetotellurics; Three dimensional; Electrical conductivity; Electrically conductive; Flat-slab subductions; Mantle transition zone; Non linear conjugate gradient (NLCG); Slab windows; Threedimensional (3-d); Wadati-Benioff Zones; Tectonics; Benioff zone; electrical conductivity; lithospheric structure; magnetotelluric method; mantle structure; Nazca plate; seismicity; slab; subduction; transition zone; Argentina; Sierras Pampeanas
Año:2013
Volumen:14
Número:8
Página de inicio:3192
Página de fin:3209
DOI: http://dx.doi.org/10.1002/ggge.20213
Título revista:Geochemistry, Geophysics, Geosystems
Título revista abreviado:Geochem. Geophys. Geosyst.
ISSN:15252027
Registro:https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_15252027_v14_n8_p3192_Burd

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Citas:

---------- APA ----------
Burd, A.I., Booker, J.R., Mackie, R., Pomposiello, C. & Favetto, A. (2013) . Electrical conductivity of the Pampean shallow subduction region of Argentina near 33 S: Evidence for a slab window. Geochemistry, Geophysics, Geosystems, 14(8), 3192-3209.
http://dx.doi.org/10.1002/ggge.20213
---------- CHICAGO ----------
Burd, A.I., Booker, J.R., Mackie, R., Pomposiello, C., Favetto, A. "Electrical conductivity of the Pampean shallow subduction region of Argentina near 33 S: Evidence for a slab window" . Geochemistry, Geophysics, Geosystems 14, no. 8 (2013) : 3192-3209.
http://dx.doi.org/10.1002/ggge.20213
---------- MLA ----------
Burd, A.I., Booker, J.R., Mackie, R., Pomposiello, C., Favetto, A. "Electrical conductivity of the Pampean shallow subduction region of Argentina near 33 S: Evidence for a slab window" . Geochemistry, Geophysics, Geosystems, vol. 14, no. 8, 2013, pp. 3192-3209.
http://dx.doi.org/10.1002/ggge.20213
---------- VANCOUVER ----------
Burd, A.I., Booker, J.R., Mackie, R., Pomposiello, C., Favetto, A. Electrical conductivity of the Pampean shallow subduction region of Argentina near 33 S: Evidence for a slab window. Geochem. Geophys. Geosyst. 2013;14(8):3192-3209.
http://dx.doi.org/10.1002/ggge.20213