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Fragmentos de meteoritos condríticos asociados con el límite Pérmico-Triásico en la Antártida
Asish R Basu1, Michail I Petaev, Robert J Poreda
1Department of Earth and Environmental Sciences, University of Rochester, Rochester, NY 14627, USA. abasu@earth.rochester.edu
Science (New York, N.Y.)
|November 25, 2003
Resumen
Fragmentos de meteoritos condríticos fueron descubiertos en rocas antárticas del final del Pérmico, coincidiendo con los encontrados en China. Esto apoya las teorías de un evento de impacto global en el límite Pérmico-Triásico.
Área de la Ciencia:
- Geología Geología Geología.
- Cosmoquímica es la cosmoquímica.
- Paleontología Paleontología.
Sus antecedentes:
- El límite entre el Pérmico y el Triásico marca un importante evento de extinción masiva.
- Los impactos de meteoritos son desencadenantes potenciales de cambios ambientales a gran escala.
- Los hallazgos anteriores sugirieron un posible evento de impacto en este límite.
Objetivo del estudio:
- Para analizar fragmentos de meteoritos encontrados en las rocas sedimentarias de la Antártida.
- Para comparar los hallazgos de la Antártida con registros geológicos similares a nivel mundial.
- Para evaluar la evidencia de un evento de impacto global en el límite Pérmico-Triásico.
Principales métodos:
- Análisis geoquímico de fragmentos de meteoritos.
- Examen mineralógico de granos metálicos, olivino, piroxeno y óxidos.
- Comparación de las relaciones químicas e isotópicas con los tipos conocidos de meteoritos (condritas de tipo CM).
Principales resultados:
- Se identificaron múltiples fragmentos de meteoritos condríticos tipo CM en rocas sedimentarias de finales del Pérmico de Graphite Peak, en la Antártida.
- La composición química de los granos metálicos y minerales de silicato en los fragmentos se alinea con las condritas de tipo CM.
- Los granos de metal discretos, similares a los encontrados en Meishan, China, también estuvieron presentes en una muestra antártica.
Conclusiones:
- La presencia de meteoritos condríticos de tipo CM en la Antártida proporciona más pruebas de la deposición de material extraterrestre al final del Pérmico.
- Los hallazgos apoyan la hipótesis de un evento de impacto global que ocurrió alrededor del límite Pérmico-Triásico.
- Este evento puede haber contribuido a los cambios ambientales que condujeron a la extinción masiva de finales del Pérmico.
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