T9.2 : Terrestrial mantle

The comparative study of terrestrial planets with "non-traditional" isotopic tracers requires a better characterization of the major terrestrial reservoirs. However, the lithospheric mantle reveals a significant isotopic heterogeneity for iron. This is related to partial melting processes but also to non-equilibrium metasomatic phenomena between peridotites and fluids circulating in the mantle. The isotopes of iron therefore appear to be sensitive tracers of metasomatic processes in the mantle of the Earth. They also show that the source of basalts, whose isotopic signatures of iron are in fact very homogeneous, is mostly located in the astenosphere.


Péridotite from the terrestrial mantle, Kerguelen Archipelago, South Atlantic Ocean (Protogranular harzburgite). Picture: M. Grégoire.

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