Carbonatite Melts and Electrical Conductivity in the Asthenosphere

Fabrice Gaillard (1) , Mohammed Malki (2) , Giada Iacono-Marziano (1, 3) , Michel Pichavant (1) , Bruno Scaillet (1)

1 ISTO - Institut des Sciences de la Terre d'Orléans
2 CEMHTI - Conditions Extrêmes et Matériaux : Haute Température et Irradiation
3 Dipartimento di Chimica e Fisica della Terra [Palermo]

Electrically conductive regions in Earth's mantle have been interpreted to reflect the presence of either silicate melt or water dissolved in olivine. On the basis of laboratory measurements, we show that molten carbonates have electrical conductivities that are three orders of magnitude higher than those of molten silicate and five orders of magnitude higher than those of hydrated olivine. High conductivities in the asthenosphere probably indicate the presence of small amounts of carbonate melt in peridotite and can therefore be interpreted in terms of carbon concentration in the upper mantle. We show that the conductivity of the oceanic asthenosphere can be explained by 0.1 volume percent of carbonatite melts on average, which agrees with the carbon dioxide content of mid-ocean ridge basalts.

Domains: Volcanology; Global Changes

Fabrice Gaillard, Mohammed Malki, Giada Iacono-Marziano, Michel Pichavant, Bruno Scaillet. Carbonatite Melts and Electrical Conductivity in the Asthenosphere. Science, 2008, 322 (5906), pp.1363 - 1365. ⟨10.1126/science.1164446⟩. ⟨insu-00343685⟩