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Evidencia de la granodiorita de Lamarck para la rápida formación de la corteza del Cretácico tardío en California
Science (New York, N.Y.)
|December 18, 1992
Resumen
Los isótopos de estroncio y neodimio revelan que la suite intrusiva de Lamarck en el batholito de Sierra Nevada se originó a partir de una fuente de manto enriquecida. Este hallazgo sugiere una importante adición de corteza juvenil durante el magmatismo del Cretácico en los Estados Unidos.
Área de la Ciencia:
- La geoquímica es la geoquímica.
- Geología de Isótopos Geología de Isótopos.
- Petrología Petrología.
Sus antecedentes:
- El batholito de Sierra Nevada es un componente importante de la cordillera norteamericana.
- Comprender su petrogénesis es clave para descifrar los procesos de crecimiento de la corteza.
- La suite intrusiva de Lamarck representa un evento magmático significativo dentro del batholito.
Objetivo del estudio:
- Para investigar el origen y la evolución de la suite intrusiva Lamarck.
- Evaluar el papel de las fuentes del manto en la formación del batholito de Sierra Nevada.
- Para refinar las estimaciones de las tasas de crecimiento de la corteza en el oeste de los Estados Unidos.
Principales métodos:
- Análisis isotópico de estroncio y neodimio en rocas gabroicas y graníticas.
- Caracterización geoquímica de la suite intrusiva de Lamarck.
- Comparación de los datos isotópicos con los yacimientos conocidos del manto y la corteza terrestre.
Principales resultados:
- Los datos isotópicos (estroncio y neodimio) muestran una variación mínima en todo el espectro de composición de la suite de Lamarck.
- Las intrusiones de Gabbro producen firmas isotópicas idénticas, consistentes con la derivación de una fuente de manto enriquecida.
- Los hallazgos desafían las suposiciones anteriores sobre el crecimiento de la corteza en la región.
Conclusiones:
- La suite intrusiva de Lamarck probablemente se formó a partir de una fuente de manto enriquecida, lo que indica una participación localizada del manto.
- Esta participación requiere revisiones a las estimaciones de la tasa de crecimiento de la corteza para los Estados Unidos.
- Algunas partes del batholito de Sierra Nevada pueden representar una corteza predominantemente juvenil formada durante el Cretácico.
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