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El drenaje continental en América del Norte durante el Fanerozoico de los isótopos de Nd
1P. J. Patchett, Department of Geosciences, University of Arizona, Tucson, AZ 85721, USA. E-mail: patchett@geo.arizona.edu. G. M. Ross, Geological Survey of Canada, 3303 33rd Street NW, Calgary AB T2L 2A7, Canada. J. D. Gleason, Lunar and Planetary La.
Science (New York, N.Y.)
|January 29, 1999
Resumen
Los datos isotópicos del neodimio revelan que las fuentes de roca sedimentaria de América del Norte cambiaron significativamente con el tiempo. Los escudos antiguos dominaron temprano, seguidos por las montañas Caledonian-Appalachian, y más tarde la Cordillera occidental.
Área de la Ciencia:
- La geoquímica es la geoquímica.
- Geología sedimentaria geología sedimentaria.
- Geología de isótopos geología de isótopos.
Sus antecedentes:
- Las rocas sedimentarias registran la historia de sus regiones de origen.
- Comprender la procedencia de los sedimentos es clave para reconstruir la paleogeografía y los eventos tectónicos.
Objetivo del estudio:
- Para rastrear las fuentes de las rocas sedimentarias en América del Norte utilizando isótopos de neodimio (Nd).
- Para establecer una línea de tiempo de los principales cambios en el suministro de sedimentos en los últimos 600 millones de años.
Principales métodos:
- Análisis de las composiciones isotópicas del neodimio (Nd) en rocas sedimentarias.
- Interpretación de firmas isotópicas para identificar fuentes de sedimentos y vías de transporte.
Principales resultados:
- Los patrones isotópicos Nd consistentes indican que el origen de los sedimentos a escala continental se encuentra en América del Norte.
- Las fuentes de escudos continentales antiguos predominaron entre hace 600 y 450 millones de años (Ma).
- Los detritos de las montañas Caledonian-Appalachian se volvieron dominantes alrededor de 450 Ma, persistiendo hasta aproximadamente 150 Ma, probablemente debido al reciclaje de rocas sedimentarias.
- La aparición de la Cordillera occidental alrededor de 150 Ma introdujo nuevos detritos en el sistema.
Conclusiones:
- Los isótopos de neodimio proporcionan una herramienta robusta para el seguimiento a largo plazo de los cambios de procedencia de los sedimentos.
- La historia de las fuentes de sedimentos de América del Norte refleja los principales eventos tectónicos y las reconstrucciones paleogeográficas.
- El reciclaje de sedimentos juega un papel importante en oscurecer o prolongar la señal de las fuentes primarias de sedimentos.
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