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Baja resistividad eléctrica asociada con el hundimiento de la losa plana de Nazca debajo de Argentina
John R Booker1, Alicia Favetto, M Cristina Pomposiello
1Department of Earth and Space Sciences, Box 351310, University of Washington, Seattle, Washington 98195, USA. booker@ess.washington.edu
Nature
|May 28, 2004
Resumen
El estudio revela un derretimiento parcial debajo de los Andes, lo que podría explicar el plano que subduce la placa de Nazca.
Área de la Ciencia:
- Geofísica y tectónica.
- Dinámica del manto y fusión.
Sus antecedentes:
- La litosfera oceánica se subduce hacia el este debajo de los Andes, generalmente formando una fuente de magma en la cuña del manto.
- Un segmento de losa plana de la placa de Nazca (28-33°S) ha detenido el volcanismo en los Andes al interrumpir la cuña del manto.
- El destino de los volátiles y el mecanismo del retroceso de la tabla plana siguen siendo poco conocidos.
Objetivo del estudio:
- Para investigar la estructura de conductividad eléctrica debajo del segmento de la losa plana en el centro de Argentina.
- Para inferir la presencia y la profundidad de la fusión parcial asociada con la placa de Nazca subductora.
- Explorar las implicaciones para el transporte volátil del manto y la dinámica de la losa plana.
Principales métodos:
- Adquisición y análisis de datos magnetotellúricos a lo largo de un perfil en el centro de Argentina.
- Interpretación de las anomalías de conductividad eléctrica mejorada.
- Modelado de la distribución parcial de la fusión y las fuentes volátiles potenciales.
Principales resultados:
- Inferida conductividad eléctrica mejorada a lo largo del flanco oriental de la placa de Nazca subductora.
- La evidencia sugiere la presencia de fusión parcial que se extiende a profundidades de al menos 250 km, posiblemente más de 400 km.
- La anomalía de conductividad puede indicar que la fusión se suministra desde la discontinuidad de 410 km.
Conclusiones:
- Los hallazgos apoyan la presencia de fusión parcial debajo de la región de la losa plana, potencialmente vinculada a la placa de subducción.
- Esta fusión parcial podría ser sostenida a profundidades significativas o suministrada desde la zona de transición del manto.
- Los resultados son consistentes con el modelo de "filtro de agua", que explica el transporte volátil y el comportamiento de la losa plana.
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