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Producción de la variabilidad isotópica en los basaltos continentales por la contaminación de la corteza críptica
Science (New York, N.Y.)
|January 3, 1992
Resumen
Las variaciones isotópicas regionales de basalto en el oeste de los Estados Unidos pueden deberse a la contaminación de la corteza terrestre, no solo del manto. Las lavas del sur de California muestran esta sutil influencia de la corteza sobre el magma basáltico de las islas oceánicas.
Área de la Ciencia:
- La geoquímica es la geoquímica.
- Geología de Isótopos Geología de Isótopos.
- Petrología Petrología.
Sus antecedentes:
- Las variaciones isotópicas regionales en los basaltos neógenos del oeste de los Estados Unidos se atribuyen típicamente a fuentes del manto subcontinental.
- Los basaltos del sur de California presentan un caso único con variabilidad isotópica vinculada a la ausencia de xenolitos.
Objetivo del estudio:
- Para investigar el origen de la variabilidad isotópica en los basaltos del sur de California.
- Determinar el papel de la contaminación de la corteza frente a las fuentes del manto en la geoquímica del basalto neogénico.
Principales métodos:
- Análisis de las composiciones isotópicas de neodimio (Nd), estroncio (Sr) y plomo (Pb) en basaltos.
- Análisis geoquímico de lavas y xenolitos derivados del manto.
- Comparación de los datos isotópicos con las composiciones de basalto de las islas oceánicas (OIB).
Principales resultados:
- La variabilidad isotópica en los basaltos del sur de California se limita a las lavas pobres en xenolitos.
- Los basaltos que contienen xenolitos exhiben composiciones isotópicas uniformes, similares a las de la OIB.
- Los datos geoquímicos sugieren una sutil contaminación de la corteza de magma similar al OIB.
Conclusiones:
- La contaminación de la corteza terrestre, particularmente por la corteza máfica, es un factor importante en las firmas isotópicas del basalto del sur de California.
- Este hallazgo reconcilia las discrepancias entre las interpretaciones tectónicas e isotópicas del manto subcontinental.
- El estudio destaca la importancia de reconocer la contaminación de la corteza críptica en los magmas derivados del manto.
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