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El termómetro de circón revela las condiciones mínimas de fusión en la Tierra más antigua
1Department of Earth and Environmental Sciences, Rensselaer Polytechnic Institute, Troy, NY 12180, USA. watsoe@rpi.edu
Science (New York, N.Y.)
|May 10, 2005
Resumen
Los circones antiguos indican que la Tierra primitiva había regulado las temperaturas y los océanos. Estos hallazgos sugieren un Eón Hadeano sorprendentemente estable, con la formación de la corteza y el reciclaje comenzando mucho antes de lo que se pensaba.
Área de la Ciencia:
- Geología Geología Geología.
- Ciencias planetarias Ciencias planetarias.
- Ciencias de la Tierra Ciencias de la Tierra Ciencias de la Tierra
Sus antecedentes:
- El Eón Hadeo (hace 4.0 a 4.5 mil millones de años) es tradicionalmente visto como un período geodinámicamente violento.
- Interpretaciones recientes sugieren un Hadeano más benigno, potencialmente con océanos similares a la Tierra.
- Comprender las temperaturas de cristalización del circón Hadeano es crucial para este debate.
Objetivo del estudio:
- Para determinar las temperaturas de cristalización de antiguos zircones de las colinas de Jack, Australia Occidental.
- Para utilizar estas temperaturas para inferir las condiciones en la Tierra temprana durante el Eón Hadeano.
Principales métodos:
- Análisis del contenido de titanio en antiguos zircones utilizando un termómetro especializado.
- Comparación de las temperaturas del circón del Hadeano con las temperaturas de crecimiento del circón granitoide moderno.
Principales resultados:
- Los circones de Hadeo exhiben una fuerte agrupación de temperaturas de cristalización alrededor de 700°C.
- Estas temperaturas son indistinguibles de las del crecimiento de zircón granitoide moderno.
- Los hallazgos apoyan la existencia de condiciones húmedas y de fusión mínima en la Tierra primitiva.
Conclusiones:
- Un mecanismo regulado para la producción de rocas que contienen circón existía durante el Eón Hadeano.
- Las condiciones húmedas de fusión mínima estuvieron presentes dentro de los 200 millones de años de formación del sistema solar.
- La Tierra probablemente estableció procesos de formación de la corteza, erosión y reciclaje de sedimentos ya hace 4.35 mil millones de años.
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