Zoned rims to garnets in sheared peridotites have been ascribed to reaction with the liquid that crystallized the megacryst suite (Griffin et al., 1989; Moore and Lock, 2001). To preserve such zoned margins, this magma must have been present immediately prior to, or at the time of kimberlite eruption (Griffin et al., 1989). This conclusion is supported by the isobaric range in megacryst equilibration temperatures in individual pipes (Gurney et al., 1979). It is also consistent with U/Pb ages for megacryst zircons, which typically span an interval from the time...

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