Subduction-related diamonds? - The evidence for a mantle-derived origin from coupled δ13C - δ15N determinations

Pierre Cartigny, Jeff W. Harris, David Phillips, Michel Girard, Marc Javoy

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107 Citations (Scopus)

Abstract

For the first time, δ13C-δ15N more than 150 diamonds of known paragenesis, originating from different localities are reported. These coupled δ13C-δ15 determinations argue against a direct formation from subducted biogenic carbon for most of these diamonds. Our data confirm the apparent isotopic disequilibrium of nitrogen between the internal (mantle) and external (atmosphere + crust) reservoirs of the Earth, and thus support the heterogeneous accretion model of the Earth inferred from earlier fibrous diamond studies. We suggest that non-fibrous diamonds have recorded the evolution of the nitrogen isotopic composition starting from a δ15N-value lower than -25‰ to the present δ15N-value around -5‰. This isotopic composition change of mantle nitrogen was built up by large recycling of nitrogen during the early history of the Earth.

Original languageEnglish
Pages (from-to)147-159
Number of pages13
JournalChemical Geology
Volume147
Issue number1-2
DOIs
Publication statusPublished - 15 May 1998
Externally publishedYes

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