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Reflectividad generalizada de las ondas sísmicas y metasomatismo de la cuña del manto de Tonga
Yingcai Zheng1, Thorne Lay, Megan P Flanagan
1Department of Earth and Planetary Sciences, University of California, Santa Cruz, CA 95064, USA.
Science (New York, N.Y.)
|April 14, 2007
Resumen
Las imágenes sísmicas revelan estructuras del manto profundo por encima de la zona de subducción de Tonga. Estas estructuras, causadas por fluidos ascendentes, son clave para comprender la Tierra.
Área de la Ciencia:
- La geofísica es la geofísica.
- Sismología Sismología.
- La tectónica es la tectónica.
Sus antecedentes:
- Las zonas de subducción son cruciales para la evolución de la corteza terrestre y el reciclaje litosférico.
- Comprender la dinámica de la cuña del manto superior por encima de las losas de subducción es vital.
- Las imágenes sísmicas proporcionan información sobre estos complejos procesos geológicos.
Objetivo del estudio:
- Para crear imágenes sísmicas en 3D de la cuña del manto superior por encima de la losa de Tonga.
- Identificar y caracterizar las interfaces reflectantes dentro de esta región.
- Para interpretar las estructuras sísmicas en términos de procesos del manto.
Principales métodos:
- Migración de las grabaciones telesísmicas de las reflexiones de ondas P y S.
- Análisis de los reflejos en la parte inferior de la placa oceánica subductora.
- Imágenes sísmicas tridimensionales del manto superior.
Principales resultados:
- Detección de reflectores débiles laterales continuos en varias profundidades (90-450 km).
- Identificación de reflectores con una topografía significativa.
- Se observaron disminuciones en las impedancias de ondas P y S a profundidades específicas, lo que indica cambios en la composición.
Conclusiones:
- La reflectividad sísmica generalizada se atribuye a las transiciones de fase y el metasomatismo.
- Los fluidos derivados de la piedra sólida que se elevan a través de la cuña del manto causan estas estructuras observadas.
- Estos hallazgos mejoran nuestra comprensión de los procesos de la zona de subducción y la generación de la corteza continental.
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