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La transición de la corteza superior arcaica de máfica a félsica marca el comienzo de la tectónica de placas
Ming Tang1, Kang Chen2, Roberta L Rudnick3
1Department of Geology, University of Maryland, College Park, MD 20742, USA. Corresponding author.
Science (New York, N.Y.)
|January 23, 2016
Resumen
El Eón Arcaico vio la corteza continental temprana evolucionar de máfico a félico. Este cambio, marcado por el aumento de la masa de la corteza, sugiere el inicio de la tectónica de placas global hace unos 3.000 millones de años.
Área de la Ciencia:
- Geología
- Geoquímica
- Las primeras ciencias de la Tierra
Sus antecedentes:
- El Eón Arcaico (hace 4.02.5 mil millones de años) fue crítico para la formación temprana de la corteza continental y el surgimiento de la vida.
- La composición inicial de la corteza continental es poco conocida debido a los procesos geológicos posteriores.
- Comprender la evolución temprana de la corteza es clave para descifrar la historia temprana de la Tierra.
Objetivo del estudio:
- Para reconstruir la composición masiva de MgO de la corteza continental superior del Arcaico.
- Para determinar el momento de los cambios de composición en la corteza continental temprana.
- Investigar la relación entre la evolución de la corteza y el inicio de la tectónica de placas.
Principales métodos:
- Análisis de las proporciones de Ni/Co y Cr/Zn en las rocas sedimentarias terrestres arcaicas.
- Análisis de las rocas ígneas y metaígneas arcaicas.
- Seguimiento geoquímico de la composición masiva de MgO en la corteza continental superior.
Principales resultados:
- La corteza continental superior arcaica evolucionó de una composición máfica a una composición en masa felsica hace entre 3.0 y 2.5 mil millones de años.
- Se produjo un aumento de cinco veces en la masa de la corteza continental superior durante este período.
- La adición de rocas graníticas contribuyó significativamente al aumento de la masa de la corteza.
Conclusiones:
- La evolución de la composición de la corteza arquea indica cambios significativos en los procesos magmáticos.
- El aumento sustancial en la masa de la corteza sugiere tasas de generación de corteza mejoradas.
- Los hallazgos apoyan la hipótesis de que la tectónica de placas global se inició hace unos 3.000 millones de años.
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