Recycled gabbro signature in hotspot magmas unveiled by plume–ridge interactions.

Stroncik, N. A. and Devey, Colin W. (2011) Recycled gabbro signature in hotspot magmas unveiled by plume–ridge interactions. Nature Geoscience, 4 . pp. 393-397. DOI 10.1038/NGEO1121.

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Supplementary data:

Abstract

Lavas erupted within plate interiors above upwelling mantle
plumes have chemical signatures that are distinct from midocean
ridge lavas. When a plume interacts with a mid-ocean
ridge, the compositions of both their lavas changes, but there
is no consensus as to how this interaction occurs1–3. For the
past 15 Myr, the Pacific–Antarctic mid-ocean ridge has been
approaching the Foundation hotspot4 and erupted lavas have
formed seamounts. Here we analyse the noble gas isotope
and trace element signature of lava samples collected from
the seamounts. We find that both intraplate and on-axis
lavas have noble gas isotope signatures consistent with the
contribution from a primitive plume source. In contrast, nearaxis
lavas show no primitive noble gas isotope signatures, but
are enriched in strontium and lead, indicative of subducted
former oceanic lower crust melting within the plume source5–7.
We propose that, in a near-ridge setting, primitive, plumesourced
magmas formed deep in the plume are preferentially
channelled to and erupted at the ridge-axis. The remaining
residue continues to rise and melt, forming the near-axis
seamounts. With the deep melts removed, the geochemical
signature of subduction contained within the residue becomes
apparent. Lavas with strontium and lead enrichments are found
worldwide where plumes meet mid-ocean ridges6–8, suggesting
that subducted lower crust is an important but previously
unrecognised plume component.

Document Type: Article
Keywords: Volcanology; Geochemistry; Mid-ocean ridges ; lavas ; noble gas isotope signatures
Research affiliation: Kiel University
OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-MUHS
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1038/NGEO1121
ISSN: 1752-0894
Projects: Future Ocean
Date Deposited: 12 Apr 2011 06:55
Last Modified: 23 Sep 2019 20:18
URI: http://oceanrep.geomar.de/id/eprint/11776

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