Melting of sediments in the deep mantle produces saline fluid inclusions in diamonds

Michael W. Förster, Stephen F. Foley, Horst R. Marschall, Olivier Alard, Stephan Buhre

Research output: Contribution to journalArticleResearchpeer-review

Abstract

Diamonds growing in the Earth's mantle often trap inclusions of fluids that are highly saline in composition. These fluids are thought to emerge from deep in subduction zones and may also be involved in the generation of some of the kimberlite magmas. However, the source of these fluids and the mechanism of their transport into the mantle lithosphere are unresolved. Here, we present experimental results showing that alkali chlorides are stable solid phases in the mantle lithosphere below 110 km. These alkali chlorides are formed by the reaction of subducted marine sediments with peridotite and show identical K/Na ratios to fluid inclusions in diamond. At temperatures >1100°C and low pressures, the chlorides are unstable; here, potassium is accommodated in mica and melt. The reaction of subducted sediments with peridotite explains the occurrence of Mg carbonates and the highly saline fluids found in diamonds and in chlorine-enriched kimberlite magmas.

LanguageEnglish
Article numbereaau2620
Pages1-6
Number of pages6
JournalScience Advances
Volume5
Issue number5
DOIs
Publication statusPublished - May 2019

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sediments
Earth mantle
diamonds
melting
inclusions
fluids
kimberlite
peridotite
chlorides
lithosphere
alkalies
mica
chlorine
solid phases
carbonates
potassium
low pressure
traps
occurrences
temperature

Bibliographical note

Copyright the Author(s) 2019. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

Cite this

Förster, Michael W. ; Foley, Stephen F. ; Marschall, Horst R. ; Alard, Olivier ; Buhre, Stephan. / Melting of sediments in the deep mantle produces saline fluid inclusions in diamonds. In: Science Advances. 2019 ; Vol. 5, No. 5. pp. 1-6.
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Melting of sediments in the deep mantle produces saline fluid inclusions in diamonds. / Förster, Michael W.; Foley, Stephen F.; Marschall, Horst R.; Alard, Olivier; Buhre, Stephan.

In: Science Advances, Vol. 5, No. 5, eaau2620, 05.2019, p. 1-6.

Research output: Contribution to journalArticleResearchpeer-review

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AU - Förster, Michael W.

AU - Foley, Stephen F.

AU - Marschall, Horst R.

AU - Alard, Olivier

AU - Buhre, Stephan

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