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La tectónica del Himalaya, los procesos de desgaste y el registro del isótopo de estroncio en las calizas marinas
Science (New York, N.Y.)
|December 4, 1992
Resumen
Las proporciones de isótopos de estroncio en el agua de mar revelan una tendencia a largo plazo influenciada por las colisiones continentales. Los principales eventos tectónicos, como la orogenia del Himalaya, alteran significativamente este registro geológico durante millones de años.
Área de la Ciencia:
- La geoquímica es la geoquímica.
- Geología de Isótopos Geología de Isótopos.
- La tectónica es la tectónica.
Sus antecedentes:
- La composición del isótopo de estroncio del agua de mar (87Sr/86Sr) ha variado significativamente a lo largo del tiempo geológico.
- Esta evolución isotópica exhibe un patrón de umbral asimétrico en los últimos 500 millones de años.
- Estudios anteriores han observado fluctuaciones, pero carecían de una explicación completa para la tendencia a gran escala.
Objetivo del estudio:
- Investigar los principales impulsores de las variaciones a largo plazo de los isótopos de estroncio en el agua de mar.
- Para correlacionar los principales eventos geológicos con los cambios observados en la relación 87Sr/86Sr.
- Para comprender la influencia de la intemperie continental y el ciclo del estroncio en la geoquímica marina.
Principales métodos:
- Análisis de datos de isótopos de estroncio de sedimentos marinos que abarcan 500 millones de años.
- Modelado geoquímico del ciclo del estroncio, incorporando la dinámica de la intemperie.
- Correlación de las tendencias isotópicas con los principales eventos tectónicos, en particular las colisiones continentales.
Principales resultados:
- La proporción 87Sr/86Sr muestra un claro fondo asimétrico, con máximos en los períodos cámbrico y reciente y un mínimo en el Jurásico.
- Los modelos geoquímicos indican que las colisiones continentales a gran escala son el factor dominante que influye en esta tendencia isotópica.
- La escala de variación isotópica sugiere que sólo las orogenias "estilo Himalaya" pueden producir cambios tan significativos.
Conclusiones:
- La orogenia del Himalaya es el evento tectónico más significativo que afecta a los isótopos de estroncio desde la orogenia panafricana.
- Las colisiones continentales, a través del aumento de la intemperie y el flujo de sedimentos, son el mecanismo principal que controla la evolución a largo plazo del agua de mar 87Sr/86Sr.
- Comprender estos vínculos es crucial para interpretar la historia geoquímica de la Tierra y la evolución tectónica.
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