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Patrones de abundancia de elementos del grupo del platino en diferentes entornos del manto
1M. Rehkamper, A. N. Halliday, D. Barfod, Department of Geological Sciences, University of Michigan, Ann Arbor, MI 48109-1063, USA. J. G. Fitton and J. B. Dawson, Department of Geology and Geophysics, University of Edinburgh, Edinburgh EH9 3JW, UK.
Science (New York, N.Y.)
|December 5, 1997
Resumen
Los patrones de elementos del grupo del platino (PGE) en los xenolitos del manto revelan distintas historias del manto superior. Los xenolitos de la línea de Camerún sugieren un manto homogéneo, mientras que los xenolitos de Tanzania indican un origen de una zona de suprasubducción rica en fluidos.
Área de la Ciencia:
- La geoquímica es la geoquímica.
- Petrología Petrología.
- Estudios sobre el xenolito del manto.
Sus antecedentes:
- Los xenolitos derivados del manto proporcionan información crucial sobre la composición y evolución del manto superior de la Tierra.
- Los elementos del grupo del platino (PGEs) son trazadores sensibles de los procesos del manto, incluida la extracción del fundido y la alteración del fluido.
Objetivo del estudio:
- Para comparar los patrones de abundancia del elemento del grupo del platino (PGE) en los xenolitos del manto de la Línea de Camerún y el norte de Tanzania.
- Para aclarar las distintas historias de evolución del manto de estas dos regiones basadas en su sistemática PGE.
Principales métodos:
- Análisis de las concentraciones de elementos del grupo del platino (EGP) en los xenolitos del manto (lerzolitas y peridotitas).
- Comparación de los patrones de PGE observados con los reservorios conocidos del manto y los entornos geológicos (por ejemplo, ofiolitos, zonas de suprasubducción).
Principales resultados:
- Las herzolitas de la línea de Camerún exhiben patrones uniformes de PGE con proporciones condríticas, indicativas de un manto superior homogéneo.
- Las peridotitas de Tanzania muestran patrones de PGE similares a las rocas ultramaficas de los ofiolitos, lo que sugiere una evolución diferente del manto.
- Las diferencias observadas se atribuyen a un desarrollo litosférico contrastante: suprasubducción rica en fluidos para Tanzania y extracción de fundición a partir de peridotitas anidras para Camerún Line.
Conclusiones:
- El manto superior debajo de la Línea de Camerún se interpreta como homogéneo y en gran parte anhidro.
- La litosfera en el norte de Tanzania probablemente se formó en un ambiente de zona de suprasubducción rica en fluidos.
- Los patrones de abundancia de PGE en los xenolitos del manto sirven como poderosos indicadores de diversos procesos del manto y entornos tectónicos.
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