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Evidencia isotópica de anoxia mesoarquea y cambio en la química atmosférica del azufre
James Farquhar1, Marc Peters, David T Johnston
1Department of Geology and ESSIC, University of Maryland, College Park, Maryland 20742, USA. jfarquha@geol.umd.edu
Nature
|October 12, 2007
Resumen
Una nueva investigación revela una señal distinta de isótopos de azufre en las rocas mesoarqueas, lo que indica que la atmósfera temprana de la Tierra se mantuvo anóxica. Este hallazgo desafía las teorías anteriores de la oxigenación temprana y la evolución atmosférica.
Área de la Ciencia:
- La geoquímica es la geoquímica.
- Paleoclimatología Paleoclimatología
- Ciencias de la atmósfera Ciencias atmosféricas.
Sus antecedentes:
- La evolución de la atmósfera de la Tierra implicó una transición significativa de bajos a altos niveles de oxígeno.
- La comprensión de esta transición es crucial para identificar el inicio de la eficiente intemperie oxidativa, los cambios en la química del océano y el cambio a la ecología aeróbica.
- La desaparición de las proporciones de isótopos de azufre no dependientes de la masa hace unos 2.45 mil millones de años es una evidencia clave de este cambio atmosférico.
Objetivo del estudio:
- Investigar la presencia y la naturaleza de la señal isotópica de azufre no dependiente de la masa durante la era mesoarquea.
- Reevaluar el momento y la extensión de la oxigenación atmosférica temprana.
Principales métodos:
- Análisis detallado de las proporciones de isótopos de azufre en rocas sedimentarias del intervalo mesoarqueo.
- Comparación de los datos de isótopos de azufre del Mesoarqueo con los registros de otros períodos del Arqueo.
Principales resultados:
- Preservación de una señal isotópica de azufre distinta y no dependiente de la masa en las rocas mesoarqueas.
- Esta señal difiere de las que se encuentran en períodos Arqueanos anteriores y posteriores.
- La evidencia sugiere que la atmósfera primitiva se mantuvo anóxica durante el Mesoarqueo.
Conclusiones:
- La atmósfera mesoarquea era en gran parte anóxica, lo que desafía las teorías de la oxigenación permanente temprana.
- La variabilidad en el registro de isótopos de azufre indica cambios en la química atmosférica y la transparencia UV antes de hace 2.45 mil millones de años.
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