title: Lead isotopes reveal bilateral asymmetry and vertical continuity in the Hawaiian mantle plume.
abstract: The two parallel chains of Hawaiian volcanoes ('Loa' and 'Kea') are known to have statistically different but overlapping radiogenic isotope characteristics. This has been explained by a model of a concentrically zoned mantle plume, where the Kea chain preferentially samples a more peripheral portion of the plume. Using high-precision lead isotope data for both centrally and peripherally located volcanoes, we show here that the two trends have very little compositional overlap and instead reveal bilateral, non-concentric plume zones, probably derived from the plume source in the mantle. On a smaller scale, along the Kea chain, there are isotopic differences between the youngest lavas from the Mauna Kea and Kilauea volcanoes, but the 550-thousand-year-old Mauna Kea lavas are isotopically identical to Kilauea lavas, consistent with Mauna Kea's position relative to the plume, which was then similar to that of present-day Kilauea. We therefore conclude that narrow (less than 50 kilometres wide) compositional streaks, as well as the larger-scale bilateral zonation, are vertically continuous over tens to hundreds of kilometres within the plume.
authors.affiliation: Max-Planck-Institut für Chemie, Postfach 3060, 55020 Mainz, Germany. wafa@mpch-mainz.mpg.de
authors.forename: W
authors.initials: W
authors.lastname: Abouchami
authors.forename: A W
authors.initials: AW
authors.lastname: Hofmann
authors.forename: S J G
authors.initials: SJ
authors.lastname: Galer
authors.forename: F A
authors.initials: FA
authors.lastname: Frey
authors.forename: J
authors.initials: J
authors.lastname: Eisele
authors.forename: M
authors.initials: M
authors.lastname: Feigenson