Note to users. If you're seeing this message, it means that your browser cannot find this page's style/presentation instructions -- or possibly that you are using a browser that does not support current Web standards. Find out more about why this message is appearing, and what you can do to make your experience of our site the best it can be.

Science 28 November 2008:
Vol. 322. no. 5906, pp. 1363 - 1365
DOI: 10.1126/science.1164446
Prev | Table of Contents | Next

Reports

Carbonatite Melts and Electrical Conductivity in the Asthenosphere

Fabrice Gaillard,1* Mohammed Malki,2,3 Giada Iacono-Marziano,1,4 Michel Pichavant,1 Bruno Scaillet1

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.

1 Centre National de la Recherche Scientifique (CNRS), Institut National des Sciences de l'Univers (INSU), Université d'Orléans, Université François Rabelais–Tours, Institut des Sciences de la Terre d'Orléans, UMR 6113, Campus Géosciences, 1A, Rue de la Férollerie, 41071 Orléans cedex 2, France.
2 Conditions Extrêmes et Matériaux: Haute Température et Irradiation (CEMHTI), CNRS, UPR3079, 1D Avenue de la Recherche Scientifique, 45071 Orléans cedex 2, France.
3 Ecole Polytechnique de l'Université d'Orléans, 8 Rue Léonard de Vinci, 45072 Orléans cedex 2, France.
4 Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Palermo, Via Ugo La Malfa 153, 90146 Palermo, Italy.

* To whom correspondence should be addressed. E-mail: gaillard{at}cnrs-orleans.fr

Read the Full Text

To Advertise     Find Products

Science. ISSN 0036-8075 (print), 1095-9203 (online)