Evidence for primordial water in Earth’s deep mantle

• Published in: Science
• Main Authors: Hallis, Lydia J., Huss, Gary R., Nagashima, Kazuhide, Taylor, G. Jeffrey, Halldórsson,, Sæmundur A., Hilton, David R., Motti, Michael J., Meech, Karen J.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: American Association for the Advancement of Science 2015
• Subjects: Baffin Island; Baffin
• Online Access: http://eprints.gla.ac.uk/111960/

The hydrogen-isotope [deuterium/hydrogen (D/H)] ratio of Earth can be used to constrain the origin of its water. However, the most accessible reservoir, Earth’s oceans, may no longer represent the original (primordial) D/H ratio, owing to changes caused by water cycling between the surface and the interior. Thus, a reservoir completely isolated from surface processes is required to define Earth’s original D/H signature. Here we present data for Baffin Island and Icelandic lavas, which suggest that the deep mantle has a low D/H ratio (δD more negative than –218 per mil). Such strongly negative values indicate the existence of a component within Earth’s interior that inherited its D/H ratio directly from the protosolar nebula.