Journal article

Harzburgite to lherzolite and back again: metasomatic processes in ultramafic xenoliths from the Wesselton kimberlite, Kimberley, South Africa

WL Griffin, SR Shee, CG Ryan, TT Win, BA Wyatt

CONTRIBUTIONS TO MINERALOGY AND PETROLOGY | SPRINGER VERLAG | Published : 1999

Abstract

Garnets from phlogopite harzburgite xenoliths from the Wesselton kimberlite show zoning from low-Ca harzburgitic cores to rims with lherzolitic Ca-Cr relations. Garnet cores are depleted in Y and HREE, but have sinuous REE patterns enriched in the MREE. Rimwards increase in Ca and decrease in Cr and Mg is accompanied by increases in Zr, Y, Ti and HREE. Secondary replacement rims on some garnets consist of garnet with low Ca and Cr, but high Mg, Ti and HREE. The zoning, and the secondary replacement rims, are attributed to different stages of a metasomatic process that has converted harzburgite to lherzolite, at temperatures near 1000°C. Modelling of zoning profiles suggests that the process ..

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University of Melbourne Researchers