Abstract

An unusual suite of zircon- and rutile-bearing eclogite xenoliths from the 172 Ma Jericho kimberlite, Northwest Territories, Canada, displays a peculiar geochemistry highlighted by extreme enrichment of high field strength elements. Most profound are the large positive Nb and Zr anomalies that are linked to a high modal abundance of niobian rutile and zircon. This peculiar geochemistry, combined with results from U-Pb geochronology, requires a complex origin involving east-dipping Paleoproterozoic subduction and partial melting of oceanic crust beneath the Slave craton, one or more metasomatic overprints prior to kimberlite entrainment, and a Mesoproterozoic thermal disturbance in the Slave lithospheric mantle possibly linked to Mackenzie igneous events.

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