Heterogeneity in mantle carbon content from CO2-undersaturated basalts
M. Le Voyer, K.A. Kelley, E. Cottrell & E.H. Hauri
Nature Communications 8, Article number: 14062 (2017)
Geochemistry Petrology Volcanology
Received: 24 March 2016 Accepted: 25 November 2016 Published online: 13 January 2017
Olivine crystals containing melt inclusions (the dark spots on the interiors) sampled from the Mariana arc. These crystals were not part of this study, but illustrate what melt inclusions look like. Credit: Alison Shaw GeologyPage
The amount of carbon present in Earth’s mantle affects the dynamics of melting, volcanic eruption style and the evolution of Earth’s atmosphere via planetary outgassing. Mantle carbon concentrations are difficult to quantify because most magmas are strongly degassed upon eruption. Here we report undegassed carbon concentrations from a new set of olivine-hosted melt inclusions from the Mid-Atlantic Ridge. We use the correlations of CO2 with trace elements to define an average carbon abundance for the upper mantle. Our results indicate that the upper mantle carbon content is highly heterogeneous, varying by almost two orders of magnitude globally, with the potential to produce large geographic variations in melt fraction below the volatile-free solidus. Such heterogeneity will manifest as variations in the depths at which melt becomes interconnected and detectable, the CO2 fluxes at mid-ocean ridges, the depth of the lithosphere-asthenosphere boundary, and mantle conductivity.
How to cite this article: Le Voyer, M. et al. Heterogeneity in mantle carbon content from CO2-undersaturated basalts. Nat. Commun. 8, 14062 doi: 10.1038/ncomms14062 (2017).
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The authors acknowledge the support of the Deep Carbon Observatory, Carnegie Institution of Washington and the Smithsonian Institution. We thank Jianhua Wang for the help with the NanoSIMS measurements, Tim Gooding for assistance with sample preparation and John Armstrong for the assistance with EMP measurements. NSF award OCE# 1258771 provides curatorial support for marine geological samples at the Graduate School of Oceanography, University of Rhode Island.
M. Le Voyer
>Present address: Department of Geology, University of Maryland, 8000 Regents Drive, College Park, Maryland 20742, USA
Carnegie Institution of Washington, Department of Terrestrial Magnetism, 5241 Broad Branch Road NW, Washington, District Of Columbia 20015-1304, USA
M. Le Voyer & E.H. Hauri
Graduate School of Oceanography, University of Rhode Island, Narragansett Bay Campus, Narragansett Rhode Island 02882, USA
Smithsonian Institution, National Museum of Natural History, PO Box 37012, MRC 119, Washington, District Of Columbia 20013-7012, USA
All authors contributed to the design of the study and the writing of the manuscript. K.A.K. obtained the sample from the URI sample collection. M.L.V. prepared the melt inclusions, performed the analyses and processed the data. E.H.H. and E.C. designed Fig. 5.
The authors declare no competing financial interests.
Correspondence to M. Le Voyer.