The growth of lithospheric diamonds

Hélène Bureau (1) , Laurent Remusat (2) , Imène Estève (2) , Daniele L Pinti (3) , Pierre Cartigny (4)

1 IMPMC - Institut de minéralogie, de physique des matériaux et de cosmochimie
2 IMPMC - Institut de minéralogie, de physique des matériaux et de cosmochimie
3 GEOTOP and Département des sciences de la Terre et de l’atmosphère, Université duQuébec àMontréal, CP 8888, Succ. Centre-Ville, Montréal,QuébecH3C 3P8, Canada
4 IPGP - Institut de Physique du Globe de Paris

Natural diamonds contain mineral and fluid inclusions that record diamond growth conditions. Replicating the growth of inclusion-bearing diamonds in a laboratory is therefore a novel diagnostic tool to constrain the conditions of diamond formation in Earth's lithosphere. By determining the carbon isotopic fractionation during diamond growth in fluids or melts, our laboratory experiments revealed that lithospheric monocrystalline and fibrous and coated diamonds grow similarly from redox reactions at isotopic equilibrium in water and carbonate-rich fluids or melts, and not from native carbon. These new results explain why most of the lithospheric diamonds are characterized by a common carbon isotopic fingerprint, inherited from their common parent fluids and not from the mantle assemblage.

Domaines: Planète et Univers [physics]; Sciences de la Terre

Hélène Bureau, Laurent Remusat, Imène Estève, Daniele L Pinti, Pierre Cartigny. The growth of lithospheric diamonds. Science Advances , 2018, ⟨10.1126/sciadv.aat1602⟩. ⟨insu-02186928⟩