Original paper

Neodymium and Strontium Isotopic Measurements on Single Subcalcic Garnet Grains from Yakutian Kimberlites

Jacob, Dorrit E.; Jagoutz, Emil; Sobolev, Nick V.

Neues Jahrbuch für Mineralogie - Abhandlungen Band 172 Heft 2-3 (1998), p. 357 - 379

42 references

published: May 1, 1998

BibTeX file

ArtNo. ESP154017202012, Price: 29.00 €

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Discrete grains of subcalcic garnets from Yakutian kimberlites have been investigated for major elements, Sm, Sr, Nd, Rb concentrations as well as for 87Sr/86Sr and 143Nd/144Nd ratios. cNdi-values range between +1 and -40.6, 87Sr/86Sr are between 0.70521 and 0.72632, confirming the very heterogeneous character of these minerals. SmlNd ratios range from 0.025 to 0.828. Strong positive correlations of 87Sr/86Sr-ratios with Cr and Mn are consistent with an origin of the subcalcic garnets from Cr-spinels from spinel-harzburgites which were subducted into depths of the diamond stability field and reacted there with a metasomatic agent producing subcalcic garnet and olivine at the expense of Cr-spinel, orthopyroxene and any remaining clinopyroxene. It is proposed that subcalcic garnets are formed episodically through time and that kimberlites randomly sample populations of these minerals which are not necessarily cogenetic.


subcalcic garnetstrace elementsdiamond indicatorspinel harzburgites