Stable isotope evidence for crustal recycling as recorded by superdeep diamonds

Antony D Burnham, Andrew R Thomson, Galina Bulanova, Simon C Kohn, Christopher B Smith, Michael J Walter

Research output: Contribution to journalLetter (Academic Journal)

26 Citations (Scopus)
426 Downloads (Pure)

Abstract

Sub-lithospheric diamonds from the Juina-5 and Collier-4 kimberlites and the Machado River alluvial deposit in Brazil have carbon isotopic compositions that co-vary with the oxygen isotopic compositions of their inclusions, which implies that they formed by a mixing process. The proposed model for this mixing process, based on interaction of slab-derived carbonate melt with reduced (carbide- or metal-bearing) ambient mantle, explains these isotopic observations. It is also consistent with the observed trace element chemistries of diamond inclusions from these localities and with the experimental phase relations of carbonated subducted crust. The 18O-enriched nature of the inclusions demonstrates that they incorporate material from crustal protoliths that previously interacted with seawater, thus confirming the subduction-related origin of superdeep diamonds. These samples also provide direct evidence of an isotopically anomalous reservoir in the deep (≥350 km) mantle.
Original languageEnglish
Pages (from-to)374-380
Number of pages7
JournalEarth and Planetary Science Letters
Volume432
Early online date3 Dec 2015
DOIs
Publication statusPublished - 15 Dec 2015

Bibliographical note

Date of Acceptance: 17/10/2015

Keywords

  • diamonds
  • stable isotopes
  • subduction
  • majorite
  • stishovite

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    Deep Mantle Recycling Revealed in Diamonds and their Mineral Inclusions

    Walter, M. J.

    1/09/121/09/15

    Project: Research

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