The Geochemistry of the Platinum-Group Elements (PGE) in Kimberlites and the Nature of the PGE in the Subcratonic Lithospheric Mantle

I. McDonald, M. J. de Wit and L. A. Bizzi
Department of Geological Sciences, University of Cape Town, Rondebosch 7700, South Africa

Summary: Kimberlites which exploit grain boundaries between SLM minerals during intrusion might assimilate and become contaminated by PGE-rich intergranular material and this will be reflected in the final PGE signature of the kimberlite. Furthermore, if a chondritic or BA-like PGE component was predominantly acquired by the SLM during the earliest stages of continental lithospheric construction, this might explain the apparent restriction of the contamination to cratonic kimberlites. The presence or absence of this signature in kimberlites might therefore be a useful indicator that the kimberlite passed through deep, cratonic (possibly diamond bearing) lithosphere at some point during ascent. Such an indicator might find application as an additional tool for assessing the diamond potential of some kimberlites emplaced in areas of poorly constrained tectonic setting.

Mineralogical Magazine; August–September 1994 v. 58A; no. 2; p. 581-582; DOI: 10.1180/minmag.1994.58A.2.39
© 1994, The Mineralogical Society
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