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Evento anoxico oceánico del Cretácico 2 desencadenado por un episodio magmático masivo
Steven C Turgeon1, Robert A Creaser
1Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta, T2G 2E3, Canada. turgeonsc@ualberta.ca
Nature
|July 18, 2008
Resumen
Los eventos anóxicos oceánicos (OAE) están relacionados con la anoxia marina y el enterramiento de carbono orgánico. Una nueva investigación revela que un pulso magmático precedió a OAE2, lo que sugiere que desencadenó un amplio secuestro de carbono a mediados del período Cretácico.
Área de la Ciencia:
- La geoquímica es la geoquímica.
- La paleoceanografía es la paleoceanografía.
- La sedimentología sedimentológica.
Sus antecedentes:
- Los eventos anóxicos oceánicos (OAE) involucraron una anoxia marina generalizada y el enterramiento de carbono orgánico.
- OAE2, en el límite cenomano / turónico, es un evento clave de mediados del Cretácico.
- El desencadenante de las OAE, particularmente el secuestro de carbono orgánico, sigue sin estar claro.
Objetivo del estudio:
- Para investigar el mecanismo de activación de OAE2.2.
- Para identificar un sustituto directo para el magmatismo que coincida con el inicio de OAE2.
- Para determinar el origen del osmio en el agua de mar durante OAE2.2.
Principales métodos:
- Análisis de las proporciones de isótopos de osmio del agua de mar en sedimentos ricos en orgánico de dos sitios.
- Aplicación de una ecuación de mezcla de dos componentes.
- Comparación de los datos de isótopos de osmio con los registros de isótopos de carbono.
Principales resultados:
- Cambios bruscos en los registros de isótopos de osmio marino en o antes de la aparición de OAE2.
- Más del 97% del osmio del agua de mar era de origen magmático durante OAE2.
- Un lapso de tiempo de hasta 23 kyr entre el magmatismo y el enterramiento de carbono orgánico.
Conclusiones:
- Un pulso magmático muy extendido probablemente desencadenó OAE2.2.
- La actividad magmática precedió y potencialmente inició el entierro significativo de carbono orgánico.
- Los datos de isótopos de osmio proporcionan un vínculo directo entre el magmatismo y el OAE2.
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