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Las restricciones de los isótopos de oxígeno en el ciclo del azufre durante los últimos 10 millones de años
Alexandra V Turchyn1, Daniel P Schrag
1Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA 02138 USA. avan@fas.harvard.edu
Science (New York, N.Y.)
|March 27, 2004
Resumen
Los isótopos de oxígeno sulfatado marino revelan cambios significativos en los últimos 10 millones de años. Las fluctuaciones del nivel del mar afectaron el ciclo del azufre, lo que condujo a menores concentraciones de sulfato en el Mioceno tardío.
Área de la Ciencia:
- La geoquímica es la geoquímica.
- La paleoceanografía es la paleoceanografía.
- La geoquímica de los isótopos es la geoquímica de los isótopos.
Sus antecedentes:
- Los registros de isótopos de oxígeno de barita marina (delta18O(SO4) proporcionan información sobre el ciclo global del azufre.
- Estudios previos indican variabilidad en el sulfato marino en escalas de tiempo geológicas.
Objetivo del estudio:
- Para investigar la variabilidad de los isótopos de oxígeno sulfatado marino en los últimos 10 millones de años.
- Comprender la influencia de las fluctuaciones del nivel del mar del Plioceno-Pleistoceno en el ciclo del azufre.
- Para reconstruir las concentraciones de sulfato del Mioceno tardío.
Principales métodos:
- Análisis de los isótopos de oxígeno en la barita marina.
- Desarrollo y aplicación de un modelo numérico que simule la dinámica del ciclo del azufre.
Principales resultados:
- Los isótopos de oxígeno sulfatado marino disminuyeron en 5 por mil durante el Plio-Pleistoceno.
- Los valores del Mioceno fueron casi constantes y ligeramente enriquecidos en comparación con los niveles modernos.
- El modelado numérico indica que las fluctuaciones del nivel del mar reducen el área de la plataforma y aumentan la erosión de pirita durante los ciclos glaciales.
- Las concentraciones de sulfato eran un 10-20% más bajas a finales del Mioceno que hoy en día.
Conclusiones:
- Los cambios en el nivel del mar impactaron significativamente el ciclo del azufre y la composición de isótopos de sulfato marino.
- El ciclo del azufre experimentó cambios sustanciales entre el Mioceno y el Pliopleistoceno.
- Los niveles de sulfato del Mioceno tardío reconstruidos eran más bajos que los valores actuales.
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