Publications des scientifiques de l'IRD

Poitrasson Franck, Delpech G., Grégoire Michel. (2013). On the iron isotope heterogeneity of lithospheric mantle xenoliths : implications for mantle metasomatism, the origin of basalts and the iron isotope composition of the Earth. Contributions to Mineralogy and Petrology, 165 (6), p. 1243-1258. ISSN 0010-7999.

Titre du document
On the iron isotope heterogeneity of lithospheric mantle xenoliths : implications for mantle metasomatism, the origin of basalts and the iron isotope composition of the Earth
Année de publication
2013
Type de document
Article référencé dans le Web of Science WOS:000319009600011
Auteurs
Poitrasson Franck, Delpech G., Grégoire Michel
Source
Contributions to Mineralogy and Petrology, 2013, 165 (6), p. 1243-1258 ISSN 0010-7999
With the aim to better understand the cause of the iron isotope heterogeneity of mantle-derived bulk peridotites, we compared the petrological, geochemical and iron isotope composition of four xenolith suites from different geodynamic settings; sub-arc mantle (Patagonia); subcontinental lithospheric mantle (Cameroon), oceanic mantle (Kerguelen) and cratonic mantle (South Africa). Although correlations were not easy to obtain and remain scattered because these rocks record successive geological events, those found between delta Fe-57, Mg, some major and trace element contents of rocks and minerals highlight the processes responsible for the Fe isotope heterogeneity. While partial melting processes only account for moderate Fe isotope variations in the mantle (< 0.2 aEuro degrees, with bulk rock values yielding a range of delta Fe-57 +/- A 0.1 aEuro degrees relative to IRMM-14), the main cause of Fe isotope heterogeneity is metasomatism (> 0.9 aEuro degrees). The kinetic nature of rapid metasomatic exchanges between low viscosity melts/fluids and their wall-rocks peridotite in the mantle is the likely explanation for this large range. There are a variety of responses of Fe isotope signatures depending on the nature of the metasomatic processes, allowing for a more detailed study of metasomatism in the mantle with Fe isotopes. The current database on the iron isotope composition of peridotite xenoliths and mafic eruptive rocks highlights that most basalts have their main source deeper than the lithospheric mantle. Finally, it is concluded that due to a complex geological history, Fe isotope compositions of mantle xenoliths are too scattered to define a mean isotopic composition with enough accuracy to assess whether the bulk silicate Earth has a mean delta Fe-57 that is chondritic, or if it is similar to 0.1 aEuro degrees above chondrites as initially proposed.
Plan de classement
Géologie et formations superficielles [064]
Localisation
Fonds IRD [F B010060350]
Identifiant IRD
fdi:010060350
Contact