El precursor de las arcillas de la frontera entre el Cretácico y el Terciario en Stevns Klint, Dinamarca, y el agujero 465A de DSDP
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Published on: August 5, 2016
Science (New York, N.Y.)
|October 12, 1984
Resumen
Los minerales de arcilla en el límite Cretácico-Terciario, incluidos Stevns Klint y DSDP Hole 465A, sugieren la formación in situ de vidrio de impacto. Estos hallazgos apoyan un evento de impacto extraterrestre como la fuente de las arcillas de frontera.
Área de la Ciencia:
- La geoquímica es la geoquímica.
- La mineralogía es la Mineralogía.
- Paleontología Paleontología.
Sus antecedentes:
- El límite entre el Cretácico y el Terciario (K/T) marca un evento de extinción significativo.
- La mineralogía de arcilla y la geoquímica en este límite proporcionan pistas sobre su causa.
- Estudios previos han analizado secciones de frontera K/T, pero los análisis mineralógicos e isotópicos detallados son cruciales.
Objetivo del estudio:
- Realizar análisis detallados de minerales, químicos e isótopos de oxígeno de minerales arcillosos y zeolitas de las regiones fronterizas de K/T.
- Para investigar el origen de los minerales de arcilla encontrados en el límite K / T en Stevns Klint, Dinamarca, y DSDP Hole 465A.
- Para determinar si los minerales de arcilla se formaron in situ a partir del vidrio de impacto o de otras fuentes.
Principales métodos:
- Difracción de rayos X (XRD) para la identificación de minerales.
- Análisis químicos de elementos principales y oligoelementos, incluido el iridio y los elementos de tierras raras.
- Análisis de isótopos de oxígeno (delta(18) O) para determinar el entorno de formación.
Principales resultados:
- La capa límite de Stevns Klint K / T contiene esmectita pura, distinta de la illita detrital circundante y las arcillas de capa mixta.
- La esmectita en Stevns Klint muestra valores de isótopos de oxígeno y química de elementos principales consistentes con la alteración in situ del vidrio de impacto.
- La zona límite del agujero 465A de DSDP contiene una capa mixta de smectita-illita con una anomalía negativa de cerio, lo que indica una formación marina, probablemente de la misma fuente de vidrio.
Conclusiones:
- Los minerales de arcilla de la frontera K / T en ambos lugares probablemente se formaron in situ por la alteración del vidrio derivado del impacto.
- Los datos mineralógicos y químicos apoyan un evento de impacto extraterrestre como la causa de la formación de arcilla de la frontera K / T.
- La presencia de minerales de arcilla específicos y sus firmas isotópicas son indicadores clave de la naturaleza del evento de la frontera K/T.
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