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La cromita extraterrestre dispersa por los sedimentos traza las huellas de un importante evento de perturbación de
Birger Schmitz1, Therese Häggström, Mario Tassinari
1Department of Earth Science, Rice University, Post Office Box 1892, Houston, TX 77251, USA. birger@gvc.gu.se
Science (New York, N.Y.)
|May 10, 2003
Resumen
Abundantes granos de cromita extraterrestre encontrados en la piedra caliza sueca indican un aumento masivo en la afluencia de meteoritos a la Tierra hace 480 millones de años. Este descubrimiento ofrece nuevos conocimientos sobre los impactos de asteroides y la entrega de materia extraterrestre.
Área de la Ciencia:
- Geología Geología Geología.
- Ciencias planetarias Ciencias planetarias.
- Paleontología Paleontología.
Sus antecedentes:
- La piedra caliza marina del Ordovícico medio en el sur de Suecia contiene abundantes granos de cromita extraterrestre.
- Estos granos se originan en meteoritos descompuestos, que datan de hace aproximadamente 480 millones de años.
- Estudios anteriores indicaron un aumento significativo en la afluencia de meteoritos durante el Ordoviciano medio.
Objetivo del estudio:
- Para investigar la anomalía de la cromita en la piedra caliza del Ordovicio medio.
- Para proporcionar evidencia de una mayor afluencia de meteoritos a la Tierra.
- Para restringir las variaciones temporales en el flujo de materia extraterrestre después de un gran evento de interrupción de asteroides.
Principales métodos:
- Análisis geoquímico de los granos de cromita.
- Cartografía geológica de depósitos de piedra caliza.
- Correlación con datos paleoclimáticos y astrofísicos.
Principales resultados:
- Descubrimiento de abundantes granos de cromita extraterrestre en un área de 250.000 kilómetros cuadrados.
- La anomalía de la cromita apoya un aumento de dos órdenes de magnitud en la afluencia de meteoritos.
- Proporciona restricciones temporales detalladas sobre el flujo de materia extraterrestre.
Conclusiones:
- El período medio del Ordovícico experimentó una tasa significativamente elevada de bombardeo de meteoritos.
- Este evento fue probablemente desencadenado por una gran perturbación de asteroides en el cinturón de asteroides.
- La cromita extraterrestre sirve como un valioso sustituto para comprender la historia de los impactos de la Tierra.
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