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Piritas biogénicas de 3.400 millones de años de antigüedad de Barberton, Sudáfrica: pruebas de isótopos de azufre

H Ohmoto¹, T Kakegawa, D R Lowe

¹Department of Geosciences, The Pennsylvania State University, University Park 16802, USA.

Science (New York, N.Y.)

|October 22, 1993

Resumen

Las bacterias antiguas redujeron el sulfato del agua de mar hace 3.400 millones de años, lo que indica bacterias activas reductoras de sulfato, océanos ricos en sulfato y una atmósfera oxigenada durante ese período.

Área de la Ciencia:

La geoquímica es la geoquímica.
Paleobiología Paleobiología.
Las condiciones de la Tierra primitiva.

Sus antecedentes:

Investigar las condiciones de los océanos y la atmósfera de la Tierra primitiva es crucial para comprender la evolución de la vida.
La formación de pirita proporciona una visión potencial de los antiguos ciclos biogeoquímicos.

Objetivo del estudio:

Para determinar el origen de la pirita del cinturón de Barberton Greenstone que data de hace 3.400 millones de años.
Para inferir las condiciones de los océanos y la atmósfera de la Tierra en ese momento.

Principales métodos:

Utilizó la espectroscopia de masa de ablación láser para analizar las composiciones isotópicas de azufre.
Examinaron granos de pirita de tamaño microscópico.

Principales resultados:

Los isótopos de azufre indican pirita formada a través de la reducción bacteriana de sulfato de agua de mar.
Los hallazgos sugieren que las bacterias reductoras de sulfato estaban activas hace 3.400 millones de años.

Conclusiones:

Los océanos eran ricos en sulfato hace 3.400 millones de años.
La atmósfera contenía cantidades significativas de oxígeno libre en ese momento.
La reducción del sulfato bacteriano fue un proceso biogeoquímico clave en el Eón Arcaico.

Palabras clave:

La disciplina de la NASA es la exobiología.No perteneciente al Centro de la NASA.

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