Highly heterogeneous depleted mantle recorded in the lower oceanic crust

Sarah Lambart, Janne M. Koornneef, Marc Alban Millet, Gareth R. Davies, Matthew Cook, C. Johan Lissenberg

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

The Earth’s mantle is heterogeneous as a result of early planetary differentiation and subsequent crustal recycling during plate tectonics. Radiogenic isotope signatures of mid-ocean ridge basalts have been used for decades to map mantle composition, defining the depleted mantle endmember. These lavas, however, homogenize via magma mixing and may not capture the full chemical variability of their mantle source. Here, we show that the depleted mantle is significantly more heterogeneous than previously inferred from the compositions of lavas at the surface, extending to highly enriched compositions. We perform high-spatial-resolution isotopic analyses on clinopyroxene and plagioclase from lower crustal gabbros drilled on a depleted ridge segment of the northern Mid-Atlantic Ridge. These primitive cumulate minerals record nearly the full heterogeneity observed along the northern Mid-Atlantic Ridge, including hotspots. Our results demonstrate that substantial mantle heterogeneity is concealed in the lower oceanic crust and that melts derived from distinct mantle components can be delivered to the lower crust on a centimetre scale. These findings provide a starting point for re-evaluation of models of plate recycling, mantle convection and melt transport in the mantle and the crust.

Original languageEnglish
Pages (from-to)482-486
Number of pages5
JournalNature Geoscience
Volume12
Issue number6
DOIs
Publication statusPublished - 1 Jun 2019

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oceanic crust
lower crust
mantle
melt
crustal recycling
mantle convection
cumulate
plate tectonics
mid-ocean ridge basalt
mantle source
clinopyroxene
hot spot
plagioclase
spatial resolution
recycling
magma
isotope
crust
mineral

Cite this

Lambart, Sarah ; Koornneef, Janne M. ; Millet, Marc Alban ; Davies, Gareth R. ; Cook, Matthew ; Lissenberg, C. Johan. / Highly heterogeneous depleted mantle recorded in the lower oceanic crust. In: Nature Geoscience. 2019 ; Vol. 12, No. 6. pp. 482-486.
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Highly heterogeneous depleted mantle recorded in the lower oceanic crust. / Lambart, Sarah; Koornneef, Janne M.; Millet, Marc Alban; Davies, Gareth R.; Cook, Matthew; Lissenberg, C. Johan.

In: Nature Geoscience, Vol. 12, No. 6, 01.06.2019, p. 482-486.

Research output: Contribution to JournalArticleAcademicpeer-review

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