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Oxigenación de la biosfera en el Arqueo Tardío y evolución atmosférica
Alan J Kaufman1, David T Johnston, James Farquhar
1Departments of Geology and Earth System Science Interdisciplinary Center, University of Maryland, College Park, MD 20742-4211, USA.
Science (New York, N.Y.)
|September 29, 2007
Resumen
El esquisto de 2,5 mil millones de años del Monte McRae revela el antiguo ciclo oxidativo del azufre.
Área de la Ciencia:
- La geoquímica es la geoquímica.
- La paleoceanografía es la paleoceanografía.
- Historia de la Tierra Temprana Historia de la Tierra Temprana
Sus antecedentes:
- El Eón Arcaico (hace 4.0 a 2.5 mil millones de años) fue un período crítico para la evolución atmosférica y oceánica de la Tierra.
- Comprender el ciclo temprano del azufre es clave para descifrar las condiciones que precedieron al Gran Evento de Oxidación.
Objetivo del estudio:
- Para investigar el estado de oxidación de la superficie del océano y la composición atmosférica durante el Arcaico.
- Para determinar el momento y el alcance de la activación del ciclo oxidativo del azufre.
Principales métodos:
- Análisis geoquímicos de alta resolución de muestras de esquisto y carbonato.
- Análisis de isótopos de azufre en rocas sedimentarias.
- Correlación de los registros geológicos entre diferentes continentes (Australia y Sudáfrica).
Principales resultados:
- El Monte McRae Shale registra la primera activación generalizada y potencialmente permanente del ciclo oxidativo del azufre.
- Los datos de isótopos de azufre sugieren cambios globales en el ciclo de azufre exogénico vinculado a la evolución atmosférica.
- La oxigenación de la superficie oceánica ocurrió al menos 50 millones de años antes de la oxigenación atmosférica persistente.
Conclusiones:
- La activación del ciclo oxidativo del azufre fue un evento global significativo en la historia temprana de la Tierra.
- La oxigenación oceánica precedió a la oxigenación atmosférica, lo que indica una compleja interacción entre los sistemas de la Tierra.
- Los hallazgos proporcionan información crucial sobre las condiciones ambientales del Eón Arcaico.
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