Metasomatic diamond growth: A multi-isotope study (C-13, N-15, S-33, S-34) of sulphide inclusions and their host diamonds from Jwaneng (Botswana) Journal Article uri icon

DCO ID 11121/2271-8179-7189-7963-CC

in language

  • eng

year of publication

  • 2009

abstract

  • {The formation of diamond through metasomatic events, from volatiles-enrichedfluids/melts brought into preexisting mantle rocks, has been suggested from a series of independent studies. However, the link between these hypothetical volatile-rich fluids and deep-seated mineral inclusions (mostly silicate and sulphides) entrapped in diamonds remains unclear, yet the relationship between these two species may provide the key to our understanding of diamond crystallization. in order to address the relationship between the origin and formation of diamonds and their mineral inclusions, we carried out the first coupled stable isotopic study (delta C-13, delta N-15 and multiple S-isotopes as delta S-34, delta S-33, Delta S-33) of diamonds containing sulphide inclusions, using samples from the Jwaneng kimberlite as our model system.|Sulphides extracted from the present collection of 55 diamonds belong to either eclogitic (E-type, 52 diamonds) or peridotitic (P-type, 3 diamonds) paragenetic suites, as attested by their Cr and Ni content (Cr0.03 wt.% for E-types and Cr>0.18 wt.% and Ni>14 wt.% for P-types). Sulphur isotopic compositions have been measured in-situ by multicollector secondary ion mass spectrometry and reveal that peridotitic sulphide inclusions in diamonds (n = 4) lie on the terrestrial fractionation line whereas Mass Independent sulphur isotope Fractionations (MIF) are preserved inside eclogitic sulphides inclusions (-0.5 parts per thousand < Delta S-33 < + 0.9 parts per thousand

volume

  • 282

issue

  • 1-4