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Título: | Mantle plumes: dynamics and geochemical signature |
Otros títulos: | Plumas mantélicas: dinámica y signatura geoquímica | Autor: | Cebriá Gómez, J. M. CSIC ORCID ; López Ruiz, J. CSIC; Doblas, Miguel de las | Palabras clave: | Plumas mantélicas Basaltos continentales Basaltos oceánicos de plateau Basaltos de islas oceánicas HIMU EM1 Manto inferior Mantle plumes Continental flood basalts Oceanic plateaux basalts Oceanic island basalts Lower mantle. |
Fecha de publicación: | 2001 | Editor: | INO Reproducciones | Resumen: | [EN] Mantle plumes constitute a secondary type of convection. Their total heat flow represents 10% of the mantle heat
loss, corresponding aproximately to 8% of the global Earth´s heat budget. Mantle plumes originate at the D” core-mantle
boundary as a result of the thermal destabilization triggered by the core heat. They ascent towards the base of the lithosphere
with a nearly spherical-shaped head followed by an elongated tail connected to the D’’ source area. During this
upwelling process, plume heads liberate some of their heat into the neighbouring mantle zones, which they also partly
assimilate.
Plumes are constituted by differentially enriched zones, as evidenced by the chemical composition of basalts in continental
flood provinces, oceanic plateaux, and oceanic islands, which are supposed to be the result of plume activity. The geochemical
and isotopic data of the last 15 years show that the more enriched domain is not uniform, and that at least three contrasted
components can be identified: HIMU, EM1, and EM2. The HIMU component is enriched in high field strength elements
and it is strongly radiogenic in Pb. The EM1 component is enriched in both large ion lithophile elements and light rare
earth elements and it displays slightly elevated Sr isotopic relationships being also depleted in radiogenic Nd and Pb. Finally,
the EM2 component is enriched in large ion lithophile elements, it is highly radiogenic in Sr, and its Nd and Pb isotopic values
are intermediate between the two other components. The most widely accepted hypothesis suggests that the HIMU component
derived from altered and dehydrated oceanic crust (~3%), while the EM1 and EM2 components represent a mixture between
the HIMU component and a small percentage of previously dehydrated 1500-2000 Ma-old pelagic and terrigenous sediments.
The less enriched domain is constituted by a mantle characterized by low 87Sr/86Sr and high Nd, Pb and He isotopic ratios. This
component, called FOZO (Focus Zone), PHEM (Primitive Helium Mantle) and C (Common Component), is thought to be
derived from the lower mantle. [ES] Las plumas constituyen un modo de convección secundario. Su flujo de calor total representa el 10% del calor que emerge a través del manto y el 8% del que globalmente pierde la Tierra. Se originan en el límite manto-núcleo, por la desestabilización que genera el calor que desprende el núcleo en la capa D”. Ascienden hacia la base de la litosfera adoptando la forma de una cabeza más o menos esférica, seguida de un tallo que conecta con su zona-fuente. Durante su ascenso la cabeza transmite parte de su exceso térmico al material que atraviesa, por lo que asimila una parte del mismo. |
Descripción: | En: III Congreso Ibérico de Geoquímica - VIII Congreso de Geoquímica de España, Zaragoza 2001. M. Lago, E. Arranz y C. Galé (Eds.) | URI: | http://hdl.handle.net/10261/11471 | ISBN: | 84-930635-8-4 |
Aparece en las colecciones: | (MNCN) Comunicaciones congresos |
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2001_Mantle_plumes_geochem_-_Zaragoza.pdf | 341,59 kB | Adobe PDF | Visualizar/Abrir |
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