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Anisotropía azimutal global en la zona de transición
Jeannot Trampert1, Hendrik Jan van Heijst
1Faculty of Earth Sciences, Utrecht University, Post Office Box 80021, 3508 TA Utrecht, Netherlands. jeannot@geo.uu.nl
Science (New York, N.Y.)
|May 23, 2002
Resumen
Los matices de las ondas de amor revelan la anisotropía azimutal en la Tierra.
Área de la Ciencia:
- La geofísica es la geofísica.
- Sismología Sismología Sismología.
- Ciencias de la Tierra Ciencias de la Tierra Ciencias de la Tierra
Sus antecedentes:
- La zona de transición del manto de la Tierra (400-660 km de profundidad) juega un papel crucial en la dinámica del manto y el ciclo químico.
- Comprender las propiedades físicas, como la anisotropía sísmica, es clave para limitar los modelos de esta región.
- La anisotropía azimutal, las variaciones direccionales en las velocidades de las ondas sísmicas, proporciona información sobre las orientaciones minerales preferidas o los tejidos textuales.
Objetivo del estudio:
- Para investigar la presencia y las características de la anisotropía azimutal dentro de la zona de transición del manto de la Tierra.
- Para utilizar datos de dispersión de ondas superficiales para sondear estructuras de velocidad sísmica a estas profundidades.
- Proporcionar nuevas restricciones sobre la mineralogía y la dinámica de la zona de transición basada en la anisotropía observada.
Principales métodos:
- Análisis de las mediciones de dispersión de ondas de superficie, centrándose específicamente en los matices de ondas de amor.
- Aplicación de las técnicas de inversión de Backus-Gilbert a los mapas de velocidad de fase anisotrópica.
- Asegurando que los núcleos de resolución sean principalmente sensibles a la zona de transición (profundidad de 400-660 km).
Principales resultados:
- Se detectó evidencia de una anisotropía azimutal significativa en la zona de transición.
- Se identificó una robusta estructura de velocidad azimutalmente anisotrópica de longitud de onda larga y larga.
- La inversión mapeó con éxito estas características anisotrópicas dentro del rango de profundidad objetivo.
Conclusiones:
- La anisotropía azimutal observada en la zona de transición tiene importantes implicaciones para la comprensión de su composición y deformación.
- Las fuentes potenciales de esta anisotropía incluyen minerales alineados, estructuras laminadas inclinadas o inclusiones de fluidos.
- Estos hallazgos ofrecen nuevas limitaciones para los modelos geodinámicos y de física mineral de la zona de transición del manto.
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