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El cuarzo de choque en las arcillas de la frontera entre el Cretácico y el Terciario: evidencia de una distribución
Science (New York, N.Y.)
|May 8, 1987
Resumen
El cuarzo de choque encontrado en todo el mundo confirma un impacto masivo de asteroides en el límite Cretácico-Terciario. Este evento de impacto creó una nube de polvo que rodeaba la tierra, apoyando la hipótesis del impacto de Alvarez.
Área de la Ciencia:
- Geología Geología Geología.
- Ciencias planetarias Ciencias planetarias.
- Paleontología Paleontología.
Sus antecedentes:
- El límite entre el Cretácico y el Terciario (K-T) marca un evento significativo de extinción masiva.
- La hipótesis del impacto de Álvarez propone que un impacto extraterrestre causó esta extinción.
Objetivo del estudio:
- Para investigar la evidencia de cuarzo conmocionado en el límite K-T.
- Para confirmar la distribución global de las eyecciones de impacto.
Principales métodos:
- Aislamiento de granos de cuarzo de las capas de arcilla límite K-T.
- Análisis de las características planas del cuarzo utilizando cristalografía.
- Difracción de rayos X para identificar rayas inducidas por el choque.
- Medición de los índices de refracción.
Principales resultados:
- Cuarzo de choque con características planas encontrado en múltiples sitios globales (Europa, Océano Pacífico, Nueva Zelanda).
- Características planas indexadas a los planos cristalográficos racionales.
- La difracción de rayos X confirmó rayas inducidas por el choque.
- Se observaron índices de refracción reducidos en granos de cuarzo sacudidos.
Conclusiones:
- La presencia de cuarzo sacudido en todo el mundo confirma un gran evento de impacto en el límite K-T.
- Las eyecciones de impacto se distribuyeron globalmente en una nube de polvo.
- Proporciona pruebas sólidas que apoyan la hipótesis de impacto de Álvarez.
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