Eclogites diamond inclusions

Sulfur occurs in a variety of forms in the mantle, the major sulfur phase is monosulfide solid solution between Fe, Ni, and Cu. Recent ion microprobe measurements on sulfide inclusions from megacrysts and pyroxenite xenohths from alkali basalts and kimberlites and in diamonds gave 5 " S-values from — 11 to - - 14%c (Chaussidon et al. 1987, 1989 Eldridge et al. 1991). Sulfur isotope variations within diamonds exhibit the same characteristics as previously described for carbon i.e., eclogitic diamonds are much more variable than peridotitic diamonds. 

Burgess, R., Turner, G., Harris, J. W. (1991) 40Ar-39Ar laser probe studies of clinopyroxene inclusions in eclogitic diamonds. Geochim. Cosmochim. Acta, 56, 389-402. 

Figure 52 Initial ENd ssr isotope plot of calculated whole-rock eclogites from Africa (Koidu—Hills and Haggerty, 1989 Orapa—Smith et al., 1989 Viljoen et al, 1996 Roberts Victor—Jagoutz et al, 1984 Smith et al., 1989 Jacob and Jagoutz, 1994 Bellsbank—Neal et al., 1990), Yakutia (Snyder et al, 1993 Jacob et al, 1994 Pearson et al., 1995a Snyder et al, 1997), and eclogitic inclusions in diamonds (Richardson, 1986 Richardson et al, 1990 1999 Smith et al, 1991). Eclogite data are initial calculated whole-rock neodymium isotope compositions. Strontium isotope compositions are from clinopyroxene only. Cratonic peridotite minerals and diamond inclusions are plotted for comparison. Arrow points to a sample from Udachnaya that has a calculated initial SNd of 484. dashed lines are...

Ireland T. R., Rudnick R. L., and Spetsius Z. (1994) Trace elements in diamond inclusions from eclogites reveal hnk to Archean granites. Earth Planet. Sci. Lett. 128, 199—213. 

Richardson S. H., Shirey S. B., Harris J. W., and Carlson R. W. (2001) Archean subduction recorded by Re-Os isotopes in eclogitic sulhde inclusions in Kimberley diamonds. Earth Planet. Sci. Lett. 191, 257-266. 

Peridotitic lithologies comprise more than 95% of the mantle lithosphere (Schulze, 1989). Thus, macrodiamonds in kimberlite are believed to come from mostly peridotitic hosts that break up during the sampling or transport that accompanies kim-berlitic volcanism. Sobolev (1974) and Hatton and Gurney (1979) noted the dichotomy that peridotite xenoliths greatly outnumber eclogite xenoliths and peridotitic silicate inclusions in diamond... 

Smith C. B., Gurney J. J., Harris J. W., Robinson D. N., Shee S. R., and Jagoutz E. (1989) Sr and Nd isotopic systematics of diamond-bearing eclogite xenoliths and eclogite inclusions in diamond from southern Africa. Kimberlites and Related Rocks. Spec. Pub. Geol. Soc. Austral., no. 14, vol. 2, pp. 853-863. 

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