|Title||Evidence for primordial water in Earth’s deep mantle|
|Publication Type||Journal Article|
|Year of Publication||2015|
|Authors||Hallis LJ, Huss GR, Nagashima K, G. Taylor J, Halldórsson SA, Hilton DR, Mottl MJ, Meech KJ|
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 However, the most accessible reservoir, Earth’s oceans, may no longer represent the original (primordial) D/H ratio, owing to changes caused by water cycling between the surface and the interior.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.