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Contrastando la producción de la corteza terrestre y las rápidas transiciones del manto debajo de las crestas de arco
Robert A Dunn1, Fernando Martinez
1Department of Geology and Geophysics, University of Hawaii, Honolulu, Hawaii 96822, USA. dunn@soest.hawaii.edu
Nature
|January 14, 2011
Resumen
La extensión de la cuenca de arco trasero revela cambios abruptos en las propiedades de la corteza del fondo marino, desafiando los modelos de evolución gradual. Esto sugiere un proceso dinámico de surgimiento del manto cerca de las zonas de subducción.
Área de la Ciencia:
- Geología Geología Geología.
- La geofísica es la geofísica.
- La tectónica es la tectónica.
Sus antecedentes:
- Las cuencas de arco trasero se forman detrás de las zonas de subducción a través de grietas y extensiones del fondo marino.
- Se espera que las lavas en las crestas de extensión cambien gradualmente a medida que se alejan de la influencia de la subducción.
- Los modelos existentes predicen cambios graduales en las propiedades de la corteza a lo largo de las crestas que se extienden.
Objetivo del estudio:
- Para investigar la naturaleza de los cambios en las propiedades de la corteza en el centro de propagación del Lau Oriental.
- Para determinar si los cambios en las propiedades de la corteza son graduales o abruptos a medida que la cresta se mueve desde el arco volcánico.
Principales métodos:
- Análisis de la morfología del fondo marino.
- Medición de las velocidades sísmicas de la corteza superior.
- Interpretación de las anomalías de la gravedad y la isostasia.
Principales resultados:
- Se observaron cambios bruscos en la morfología del fondo marino, las velocidades sísmicas (más del 20% de aumento) y el grosor de la corteza (más de 1,9 km de adelgazamiento).
- Estos cambios ocurrieron con una separación mínima (tan solo 5 km) del eje de la cresta del frente volcánico.
- Las variaciones transversales y longitudinales en las propiedades de la corteza fueron significativas y repentinas.
Conclusiones:
- Los hallazgos contradicen los modelos que predicen la evolución gradual de la corteza terrestre.
- Los cambios bruscos sugieren una rápida evolución del manto arrastrado, con una zona de surgimiento dinámico que captura y luego libera el manto rico en agua.
- Este proceso dinámico desafía la formación de regiones ascendentes estables, amplias y triangulares típicas de las crestas oceánicas centrales cerca de las esquinas de la cuña del manto.
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